PUBLICATIONS
BGC is dedicated to furthering the study of the innovations in the industries we serve. As part of our team’s professional development, BGC experts co-author articles and technical publications and present many of them at industry conferences. Recent publications by BGC staff are listed below. To request a copy of a publication, please reach out to our BGC Library team at [email protected]. Due to copyright restrictions, we may not be able to provide copies of all the publications listed below.
2022
Strouth, Alex; LeSueur, Philip; McDougall, Scott
ALARP and Other Conditions for Tolerating Geohazard Risks Conference
Geohazards 8, 2022.
@conference{Conference1,
title = {ALARP and Other Conditions for Tolerating Geohazard Risks},
author = {Alex Strouth and Philip LeSueur and Scott McDougall},
year = {2022},
date = {2022-12-29},
urldate = {2022-12-29},
booktitle = {Geohazards 8},
abstract = {Geohazard areas are commonly in the transitional ‘grey-zone’ between clearly safe enough and clearly unacceptable. Here, tolerance of geohazard risk tends to be conditional, meaning that the risk can be lived with if certain conditions are met. A commonly cited condition is that risk must be reduced until it is As Low As Reasonably Practicable (ALARP). However, inconsistent definitions of ALARP are in use, which has led to miscommunication and poor decisions. Rather than referencing ALARP as the default condition for tolerating risk, specific, clear, and achievable conditions should be applied. Conditions for tolerating geohazard risks could include keeping the risk under review, following good practice to manage risks, using available resources to reduce risk, applying cost-effective measures to reduce risk, or reducing risk until the cost of further risk reduction is grossly disproportionate to the benefit gained. Risk management decisions must also consider the costs of risk reduction, which extend beyond the price of mitigation structures.},
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}
Geohazard areas are commonly in the transitional ‘grey-zone’ between clearly safe enough and clearly unacceptable. Here, tolerance of geohazard risk tends to be conditional, meaning that the risk can be lived with if certain conditions are met. A commonly cited condition is that risk must be reduced until it is As Low As Reasonably Practicable (ALARP). However, inconsistent definitions of ALARP are in use, which has led to miscommunication and poor decisions. Rather than referencing ALARP as the default condition for tolerating risk, specific, clear, and achievable conditions should be applied. Conditions for tolerating geohazard risks could include keeping the risk under review, following good practice to manage risks, using available resources to reduce risk, applying cost-effective measures to reduce risk, or reducing risk until the cost of further risk reduction is grossly disproportionate to the benefit gained. Risk management decisions must also consider the costs of risk reduction, which extend beyond the price of mitigation structures.
Jakob, Matthias; Davidson, Sarah; Bullard, Gemma; Busslinger, Matthias; Collier-Pandya, Beatrice; Grover, Patrick; Lau, Carie-Ann
Debris-Flood Hazard Assessments in Steep Streams Journal Article
In: Water Resources Research, vol. 58, no. 4, 2022.
@article{article1,
title = {Debris-Flood Hazard Assessments in Steep Streams},
author = {Matthias Jakob and Sarah Davidson and Gemma Bullard and Matthias Busslinger and Beatrice Collier-Pandya and Patrick Grover and Carie-Ann Lau},
doi = {10.1029/2021WR030907},
year = {2022},
date = {2022-11-14},
urldate = {2022-11-13},
journal = {Water Resources Research},
volume = {58},
number = {4},
abstract = {Debris floods most commonly occur in steep mountain channels and on their alluvial fans
but can also occur on small gravel bed rivers with watershed areas up to several hundred square kilometers.
This became obvious during July 2021 and November 2021 debris floods in northwestern Germany and
southwestern British Columbia, Canada. We subdivide debris floods into three categories: those triggered by
a supra-critical bed shear stress ratio, form by dilution from debris flows, and resulting from outbreak floods.
This trichotomy challenges traditional hazard assessments; debris floods classify as a fluvial process, yet their
destructive mechanics are difficult to characterize. Key hazards interact spatially and temporally in debris
floods: inundation, scour, sediment transport and deposition and bank erosion. We describe approaches to
quantify hazards by systematically accounting for these processes and introduce a novel approach for hazard
quantification and mapping in which flow velocity, depth, and presumed fluid density are combined with
the annual event frequency for all event scenarios. The derivative “composite hazard maps” are equally valid
for debris floods and debris flows. Isolines of bank erosion based on a probabilistic analysis of a physically
based model are added to capture the potential of debris floods to abruptly widen their channels. Substantial
challenges remain, specifically in the reliable prediction of sediment transport and progressive bank erosion.
Our intention is to homogenize debris-flood hazard assessments and especially mapping methodologies. This
could allow for systematic integration with landuse policies assuring consistency among approaches executed
by practitioners acting in this field.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Debris floods most commonly occur in steep mountain channels and on their alluvial fans
but can also occur on small gravel bed rivers with watershed areas up to several hundred square kilometers.
This became obvious during July 2021 and November 2021 debris floods in northwestern Germany and
southwestern British Columbia, Canada. We subdivide debris floods into three categories: those triggered by
a supra-critical bed shear stress ratio, form by dilution from debris flows, and resulting from outbreak floods.
This trichotomy challenges traditional hazard assessments; debris floods classify as a fluvial process, yet their
destructive mechanics are difficult to characterize. Key hazards interact spatially and temporally in debris
floods: inundation, scour, sediment transport and deposition and bank erosion. We describe approaches to
quantify hazards by systematically accounting for these processes and introduce a novel approach for hazard
quantification and mapping in which flow velocity, depth, and presumed fluid density are combined with
the annual event frequency for all event scenarios. The derivative “composite hazard maps” are equally valid
for debris floods and debris flows. Isolines of bank erosion based on a probabilistic analysis of a physically
based model are added to capture the potential of debris floods to abruptly widen their channels. Substantial
challenges remain, specifically in the reliable prediction of sediment transport and progressive bank erosion.
Our intention is to homogenize debris-flood hazard assessments and especially mapping methodologies. This
could allow for systematic integration with landuse policies assuring consistency among approaches executed
by practitioners acting in this field.
but can also occur on small gravel bed rivers with watershed areas up to several hundred square kilometers.
This became obvious during July 2021 and November 2021 debris floods in northwestern Germany and
southwestern British Columbia, Canada. We subdivide debris floods into three categories: those triggered by
a supra-critical bed shear stress ratio, form by dilution from debris flows, and resulting from outbreak floods.
This trichotomy challenges traditional hazard assessments; debris floods classify as a fluvial process, yet their
destructive mechanics are difficult to characterize. Key hazards interact spatially and temporally in debris
floods: inundation, scour, sediment transport and deposition and bank erosion. We describe approaches to
quantify hazards by systematically accounting for these processes and introduce a novel approach for hazard
quantification and mapping in which flow velocity, depth, and presumed fluid density are combined with
the annual event frequency for all event scenarios. The derivative “composite hazard maps” are equally valid
for debris floods and debris flows. Isolines of bank erosion based on a probabilistic analysis of a physically
based model are added to capture the potential of debris floods to abruptly widen their channels. Substantial
challenges remain, specifically in the reliable prediction of sediment transport and progressive bank erosion.
Our intention is to homogenize debris-flood hazard assessments and especially mapping methodologies. This
could allow for systematic integration with landuse policies assuring consistency among approaches executed
by practitioners acting in this field.
Kostaschuk, Rod; Gaib, Sarah; Gygax, Adrian
Design and Construction of Stabilization Measures for Highway 99, Ten Mile Slide, Lillooet, BC Conference
GeoCalgary, 2022.
@conference{Conference1,
title = {Design and Construction of Stabilization Measures for Highway 99, Ten Mile Slide, Lillooet, BC},
author = {Rod Kostaschuk and Sarah Gaib and Adrian Gygax},
year = {2022},
date = {2022-11-11},
urldate = {2022-11-20},
booktitle = {GeoCalgary},
abstract = {Slope stabilization at the Ten Mile Slide undertaken by the BC Ministry of Transportation and Infrastructure (Ministry) on Highway 99 was successfully completed in Fall 2021, resulting in improved long-term safety and reliability for people and goods travelling the highway and the CN rail line above, supporting the local forestry, mining and agricultural resource sectors. Highway 99 is an essential route between the rural communities of Lillooet, Xaxli’p first nation and transportation networks in Kamloops. The landslide has been active for decades and now spans the highway approximately 17 km northeast of Lillooet on the south side of the Fraser River. Ten Mile Slide is 200 m wide at the highway and 300 m long with an estimated volume of 1,000,000 m3 of soil material and forms part of a much larger, dormant “soil glacier” called the Tunnel Earthflow. The slide is a geotechnical anomaly being one of the only known continuously moving landslides in North America. Prior to stabilization, average movement rates were typically 10 mm/day with rates up to 50 mm/day following precipitation events.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Slope stabilization at the Ten Mile Slide undertaken by the BC Ministry of Transportation and Infrastructure (Ministry) on Highway 99 was successfully completed in Fall 2021, resulting in improved long-term safety and reliability for people and goods travelling the highway and the CN rail line above, supporting the local forestry, mining and agricultural resource sectors. Highway 99 is an essential route between the rural communities of Lillooet, Xaxli’p first nation and transportation networks in Kamloops. The landslide has been active for decades and now spans the highway approximately 17 km northeast of Lillooet on the south side of the Fraser River. Ten Mile Slide is 200 m wide at the highway and 300 m long with an estimated volume of 1,000,000 m3 of soil material and forms part of a much larger, dormant “soil glacier” called the Tunnel Earthflow. The slide is a geotechnical anomaly being one of the only known continuously moving landslides in North America. Prior to stabilization, average movement rates were typically 10 mm/day with rates up to 50 mm/day following precipitation events.
Froese, Corey; Engelbrecht, Jeanine; Gousseau, Zachary; Diederichs, Kaitlyn; Zahradka, Aron
Development of Landslide Early Warning Thresholds for Normally Slow-Moving Landslide in the Western Canada Sedimentary Basin Conference
Geohazards 8, 2022.
@conference{Conference1,
title = {Development of Landslide Early Warning Thresholds for Normally Slow-Moving Landslide in the Western Canada Sedimentary Basin},
author = {Corey Froese and Jeanine Engelbrecht and Zachary Gousseau and Kaitlyn Diederichs and Aron Zahradka},
year = {2022},
date = {2022-11-01},
urldate = {2022-11-01},
booktitle = {Geohazards 8},
journal = {Canadian Geohazards Conference },
abstract = {In 2021, a project in the Western Canada Sedimentary Basin brought together five pipeline operators to support building a regional understanding of the relationships between landslide velocity and variations in hydroclimatic parameters, such as snow melt, precipitation, and soil moisture. Over 300 slope inclinometers, 40 Shape Accel Arrays, and regional InSAR displacement data were utilized to build time-displacement plots for over 40 individual slopes to review velocity trends ranging back nearly 30 years. These data were then compared with satellite-derived climate models to support the assessment of the effect of different hydroclimatic parameters on historical landslide accelerations. The initial data review highlighted spatial and temporal variations in the relative importance of hydroclimatic conditions, especially soil moisture and precipitation, in driving landslide activity accelerations. These observations will support regional situational awareness and ultimately the development of data driven exceedance alerts for landslide early warning.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In 2021, a project in the Western Canada Sedimentary Basin brought together five pipeline operators to support building a regional understanding of the relationships between landslide velocity and variations in hydroclimatic parameters, such as snow melt, precipitation, and soil moisture. Over 300 slope inclinometers, 40 Shape Accel Arrays, and regional InSAR displacement data were utilized to build time-displacement plots for over 40 individual slopes to review velocity trends ranging back nearly 30 years. These data were then compared with satellite-derived climate models to support the assessment of the effect of different hydroclimatic parameters on historical landslide accelerations. The initial data review highlighted spatial and temporal variations in the relative importance of hydroclimatic conditions, especially soil moisture and precipitation, in driving landslide activity accelerations. These observations will support regional situational awareness and ultimately the development of data driven exceedance alerts for landslide early warning.
Roesky, Benjamin; Hayashi, Masaki
Effects of Lake-Groundwater Interaction on the Thermal Regime of a Sub-Alpine Headwater Stream Journal Article
In: Hydrological Processes, vol. 36, no. 2, 2022.
@article{article1,
title = {Effects of Lake-Groundwater Interaction on the Thermal Regime of a Sub-Alpine Headwater Stream},
author = {Benjamin Roesky and Masaki Hayashi},
doi = {10.1002/hyp.14501},
year = {2022},
date = {2022-10-28},
urldate = {2022-07-20},
journal = {Hydrological Processes},
volume = {36},
number = {2},
abstract = {Stream thermal regimes are critical to the stability of freshwater habitats. There is growing concern that climate change will result in stream warming due to rising air temperatures, decreased shading in forested areas due to wildfires, and changes in streamflow. Groundwater plays an important role in controlling stream temperatures in mountain headwaters, where it makes up a considerable portion of discharge. This study investigated the controls on the thermal regime of a headwater stream, and the surrounding groundwater processes, in a catchment on the eastern slopes of the Canadian Rocky Mountains. Groundwater discharge to the headwater spring is partially sourced by a seasonal lake. Spring, stream, and lake temperature, water level, discharge and chemistry data were used to build a conceptual model of the system. Meteorological data was used to set up a stream temperature model. This study presents a unique example of an indirectly lake-headed stream, i.e., a lake that only has transient subsurface hydrologic connections to the stream and no surface connections. The interaction of groundwater and lake water, and the subsurface connectivity between the lake and the headwater spring determine the resulting stream temperature. Radiation dominated the non-advective fluxes in the stream energy balance. Sensible and latent heat fluxes play a secondary role, but their effects generally cancel out. During snowfall events, the latent heat associated with melting of direct snowfall onto the water surface was responsible for rapid stream cooling. An increase in advective inputs from groundwater and hillslope pathways did not result in observed cooling of stream water during rainfall events. The results from this study will assist water resource and fisheries managers in adapting to stream temperature changes under a warming climate.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Stream thermal regimes are critical to the stability of freshwater habitats. There is growing concern that climate change will result in stream warming due to rising air temperatures, decreased shading in forested areas due to wildfires, and changes in streamflow. Groundwater plays an important role in controlling stream temperatures in mountain headwaters, where it makes up a considerable portion of discharge. This study investigated the controls on the thermal regime of a headwater stream, and the surrounding groundwater processes, in a catchment on the eastern slopes of the Canadian Rocky Mountains. Groundwater discharge to the headwater spring is partially sourced by a seasonal lake. Spring, stream, and lake temperature, water level, discharge and chemistry data were used to build a conceptual model of the system. Meteorological data was used to set up a stream temperature model. This study presents a unique example of an indirectly lake-headed stream, i.e., a lake that only has transient subsurface hydrologic connections to the stream and no surface connections. The interaction of groundwater and lake water, and the subsurface connectivity between the lake and the headwater spring determine the resulting stream temperature. Radiation dominated the non-advective fluxes in the stream energy balance. Sensible and latent heat fluxes play a secondary role, but their effects generally cancel out. During snowfall events, the latent heat associated with melting of direct snowfall onto the water surface was responsible for rapid stream cooling. An increase in advective inputs from groundwater and hillslope pathways did not result in observed cooling of stream water during rainfall events. The results from this study will assist water resource and fisheries managers in adapting to stream temperature changes under a warming climate.
de Guzman, Earl; Alfaro, Marolo; Arenson, Lukas; Dore, Guy
Geosynthetic-Reinforced Embankment in Cold Regions: Observations and Numerical Simulations Journal Article
In: Geosynthetics International, 2022.
@article{article1,
title = {Geosynthetic-Reinforced Embankment in Cold Regions: Observations and Numerical Simulations },
author = {Earl de Guzman and Marolo Alfaro and Lukas Arenson and Guy Dore},
doi = {10.1680/jgein.21.00088},
year = {2022},
date = {2022-09-29},
urldate = {2022-09-29},
journal = {Geosynthetics International},
abstract = {An embankment underlain by permafrost foundation was reinforced with wicking woven geotextiles at its side slopes to reduce slope displacements when the fill material that was compacted at frozen condition thaws during subsequent spring and summer seasons following winter construction. The embankment fill and permafrost foundation were instrumented with thermistor strings to monitor soil temperatures as well as ShapeAccelArrays installed at the mid-slope of the embankment to measure displacements. A numerical model was developed in a commercially-available finite element software to simulate the thermal and mechanical behaviour of this embankment and further understand the benefit of using woven geotextiles in cold regions. A sequentially-coupled approach was used where temperature-dependent mechanical properties were invoked based on a heat transfer analysis. Four years of monitored results from the reinforced embankment were used to calibrate the numerical model. An adjacent section of the embankment without the geotextiles was also modelled and results show a significant reduction in slope displacements. The monitored performance and the model results presented will improve the design guidelines for embankments in cold regions using geotextiles.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An embankment underlain by permafrost foundation was reinforced with wicking woven geotextiles at its side slopes to reduce slope displacements when the fill material that was compacted at frozen condition thaws during subsequent spring and summer seasons following winter construction. The embankment fill and permafrost foundation were instrumented with thermistor strings to monitor soil temperatures as well as ShapeAccelArrays installed at the mid-slope of the embankment to measure displacements. A numerical model was developed in a commercially-available finite element software to simulate the thermal and mechanical behaviour of this embankment and further understand the benefit of using woven geotextiles in cold regions. A sequentially-coupled approach was used where temperature-dependent mechanical properties were invoked based on a heat transfer analysis. Four years of monitored results from the reinforced embankment were used to calibrate the numerical model. An adjacent section of the embankment without the geotextiles was also modelled and results show a significant reduction in slope displacements. The monitored performance and the model results presented will improve the design guidelines for embankments in cold regions using geotextiles.
Willis, Sarah
Granular Filter Design and Performance Considerations for Aging Embankment Dams Masters Thesis
2022.
@mastersthesis{Thesis1,
title = {Granular Filter Design and Performance Considerations for Aging Embankment Dams},
author = {Sarah Willis},
doi = {10.7939/r3-abg4-ag41},
year = {2022},
date = {2022-09-23},
urldate = {2022-09-23},
abstract = {Embankment dams have been constructed in Canada and the United States for over one hundred years. Embankment dams are owned by government bodies, mining and resource companies, hydroelectric producers, and other entities. Dams that have been in service for many years may have a high hazard rating due to the consequences of potential failure, as development tends to expand towards these structures over time. Older embankment dams precede the development of modern filter design criteria, which were first developed in the 1920s and have undergone considerable progress and refinement since. The lack of appropriate filter design in aging dams may increase risk of internal erosion and eventual failure. Risk assessment procedures and monitoring programs are the primary tools used by dam owners and operators to evaluate the risk of and detect potential failure events. A brief summary of modern filter design has been presented. Traditional particle-sized based criteria were reviewed and recent developments in constriction-based criteria were discussed. Considerations for challenging base soils, such as dispersive and broadly graded soils, were provided. The effects of aging on dam filter properties and performance were discussed. Evidence of filter degradation over time exists in the literature and has been attributed to several causes. These factors include filter clogging, changes in water quality, mechanical degradation, and the development of internal instability and each has been examined. A discussion of risk assessment and monitoring for aging dams has been provided. Three of the most widely-used methods were summarized. Most risk assessment methods use a potential failure mode analysis framework. The numerous uncertainties associated with an aging structure presents challenges when attempting to apply potential failure mode analysis. The results of a risk assessment investigation are typically used to identify areas that may require additional investigation, potential remediation actions, or increased monitoring. They are also used as a basis for emergency planning. Monitoring techniques provide information about the location and rate of seepage in and through the embankment. Monitoring is typically the first indication of an internal erosion event that may lead to failure. Improvements in monitoring techniques have decreased detection time and increase likelihood of successful interventions that prevent failure.},
keywords = {},
pubstate = {published},
tppubtype = {mastersthesis}
}
Embankment dams have been constructed in Canada and the United States for over one hundred years. Embankment dams are owned by government bodies, mining and resource companies, hydroelectric producers, and other entities. Dams that have been in service for many years may have a high hazard rating due to the consequences of potential failure, as development tends to expand towards these structures over time. Older embankment dams precede the development of modern filter design criteria, which were first developed in the 1920s and have undergone considerable progress and refinement since. The lack of appropriate filter design in aging dams may increase risk of internal erosion and eventual failure. Risk assessment procedures and monitoring programs are the primary tools used by dam owners and operators to evaluate the risk of and detect potential failure events. A brief summary of modern filter design has been presented. Traditional particle-sized based criteria were reviewed and recent developments in constriction-based criteria were discussed. Considerations for challenging base soils, such as dispersive and broadly graded soils, were provided. The effects of aging on dam filter properties and performance were discussed. Evidence of filter degradation over time exists in the literature and has been attributed to several causes. These factors include filter clogging, changes in water quality, mechanical degradation, and the development of internal instability and each has been examined. A discussion of risk assessment and monitoring for aging dams has been provided. Three of the most widely-used methods were summarized. Most risk assessment methods use a potential failure mode analysis framework. The numerous uncertainties associated with an aging structure presents challenges when attempting to apply potential failure mode analysis. The results of a risk assessment investigation are typically used to identify areas that may require additional investigation, potential remediation actions, or increased monitoring. They are also used as a basis for emergency planning. Monitoring techniques provide information about the location and rate of seepage in and through the embankment. Monitoring is typically the first indication of an internal erosion event that may lead to failure. Improvements in monitoring techniques have decreased detection time and increase likelihood of successful interventions that prevent failure.
Déri-Takács, Judit; Rostron, Benjamin; Mendoza, Carl; Madlener, Reinhard
Hydrogeochemical Characteristics Refine the Conceptual Model of Groundwater Flow Wood Buffalo National Park, Canada Journal Article
In: Water, vol. 14, no. 6, 2022.
@article{article1,
title = {Hydrogeochemical Characteristics Refine the Conceptual Model of Groundwater Flow Wood Buffalo National Park, Canada},
author = {Judit Déri-Takács and Benjamin Rostron and Carl Mendoza and Reinhard Madlener},
doi = {10.3390/w14060965},
year = {2022},
date = {2022-09-15},
journal = {Water},
volume = {14},
number = {6},
abstract = {Wood Buffalo National Park (WBNP), the largest national park of Canada, has unique and complex ecosystems that depend on specific water quantity and quality. We characterize groundwaters and surface waters in WBNP by determining their chemical compositions and water types, the dominant hydrochemical processes affecting their compositions, and their hydrochemical characteristics in relation to interpreted groundwater flow systems. Total Dissolved Solid concentrations in groundwaters and surface waters range from ≤10 mg/L to ≥300,000 mg/L. Four distinct water type groups are found (1) Ca-SO4-type waters occur in multiple clusters across the area in outcrop areas of Devonian evaporites; (2) Na-Cl-type waters predominantly occur in the Salt plains region along the central eastern boundary, overlapping evaporite and carbonate-dominated bedrock formations; (3) Ca-HCO3-type waters dominate the Peace-Athabasca Delta-region in the south and most of the central region; and (4) “mixed” waters. Solutes in the waters originate from three main processes dissolution of halite, dissolution of sulphate minerals, and dissolution of carbonates. The spatial occurrence of hydrochemical characteristics correlate with hypothesized groundwater flow systems, i.e., Ca-SO4 and Na-Cl-type waters coincide with discharge areas of intermediate to regional groundwater flow paths, and Ca-HCO3-type waters overlap with recharge areas. The findings of this study contribute to advancing knowledge on the hydrochemical characteristics of this remote and highly protected region of Alberta, Canada, and are important components of any further, comprehensive assessment of the natural water conditions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Wood Buffalo National Park (WBNP), the largest national park of Canada, has unique and complex ecosystems that depend on specific water quantity and quality. We characterize groundwaters and surface waters in WBNP by determining their chemical compositions and water types, the dominant hydrochemical processes affecting their compositions, and their hydrochemical characteristics in relation to interpreted groundwater flow systems. Total Dissolved Solid concentrations in groundwaters and surface waters range from ≤10 mg/L to ≥300,000 mg/L. Four distinct water type groups are found (1) Ca-SO4-type waters occur in multiple clusters across the area in outcrop areas of Devonian evaporites; (2) Na-Cl-type waters predominantly occur in the Salt plains region along the central eastern boundary, overlapping evaporite and carbonate-dominated bedrock formations; (3) Ca-HCO3-type waters dominate the Peace-Athabasca Delta-region in the south and most of the central region; and (4) “mixed” waters. Solutes in the waters originate from three main processes dissolution of halite, dissolution of sulphate minerals, and dissolution of carbonates. The spatial occurrence of hydrochemical characteristics correlate with hypothesized groundwater flow systems, i.e., Ca-SO4 and Na-Cl-type waters coincide with discharge areas of intermediate to regional groundwater flow paths, and Ca-HCO3-type waters overlap with recharge areas. The findings of this study contribute to advancing knowledge on the hydrochemical characteristics of this remote and highly protected region of Alberta, Canada, and are important components of any further, comprehensive assessment of the natural water conditions.
Strouth, Alex; McDougall, Scott
Individual Risk Evaluation for Landslides: Key Details Journal Article
In: Landslides, vol. 19, no. 4, pp. 977-991, 2022.
@article{article1,
title = {Individual Risk Evaluation for Landslides: Key Details},
author = {Alex Strouth and Scott McDougall},
doi = {10.1007/s10346-021-01838-8},
year = {2022},
date = {2022-08-26},
urldate = {2022-01-20},
journal = {Landslides},
volume = {19},
number = {4},
pages = {977-991},
abstract = {Risk-taking is an essential part of life. As individuals, we evaluate risks intuitively and often subconsciously by comparing the perceived risks with expected benefits. We do this so commonly that it passes unnoticed, like when we decide to speed home from work or go for a swim. The comparison changes, however, when one entity (such as a government) imposes a risk evaluation on another person. For example, in a quantitative risk management framework, the estimated risk is compared with a tolerable risk threshold to decide if the person is ‘safe enough’. Landslide risk management methods are well established and there is consensus on tolerable life-loss risk thresholds. However, beneath this consensus lie several key details that are explored by this article, along with suggestions for refinement. Specifically, we suggest using the risk unit, micromort (one micromort equals a life loss risk of 1 in 1 million), in describing risk estimates and thresholds, to improve risk communication. For risk estimation, we provide guidance for defining and combining landslide scenarios and for recognizing where unquantified risk from low-probability/high-consequence scenarios ought to inform risk management decisions. For risk tolerance thresholds, we highlight the pitfalls of selecting unachievably low thresholds and suggest that there is no single universal threshold. Additionally, we argue that gross disproportion between costs and benefits of further risk reduction, which is integral to the As Low As Reasonably Practicable (ALARP) principle, is a commonly unachievable and counter-productive condition for risk tolerance, and other conditions centered on proportionality often apply. Finally, we provide several figures that can be used as risk communication tools, to provide context for risk estimates and risk tolerance thresholds when these values are reported to decision makers and the public.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Risk-taking is an essential part of life. As individuals, we evaluate risks intuitively and often subconsciously by comparing the perceived risks with expected benefits. We do this so commonly that it passes unnoticed, like when we decide to speed home from work or go for a swim. The comparison changes, however, when one entity (such as a government) imposes a risk evaluation on another person. For example, in a quantitative risk management framework, the estimated risk is compared with a tolerable risk threshold to decide if the person is ‘safe enough’. Landslide risk management methods are well established and there is consensus on tolerable life-loss risk thresholds. However, beneath this consensus lie several key details that are explored by this article, along with suggestions for refinement. Specifically, we suggest using the risk unit, micromort (one micromort equals a life loss risk of 1 in 1 million), in describing risk estimates and thresholds, to improve risk communication. For risk estimation, we provide guidance for defining and combining landslide scenarios and for recognizing where unquantified risk from low-probability/high-consequence scenarios ought to inform risk management decisions. For risk tolerance thresholds, we highlight the pitfalls of selecting unachievably low thresholds and suggest that there is no single universal threshold. Additionally, we argue that gross disproportion between costs and benefits of further risk reduction, which is integral to the As Low As Reasonably Practicable (ALARP) principle, is a commonly unachievable and counter-productive condition for risk tolerance, and other conditions centered on proportionality often apply. Finally, we provide several figures that can be used as risk communication tools, to provide context for risk estimates and risk tolerance thresholds when these values are reported to decision makers and the public.
Scheip, Corey; Wegmann, Karl
Insights on the Growth and Mobility of Debris Flows from Repeat High-Resolution Lidar Journal Article
In: Landslides, vol. 19, no. 6, pp. 1297-1319, 2022.
@article{article1,
title = {Insights on the Growth and Mobility of Debris Flows from Repeat High-Resolution Lidar},
author = {Corey Scheip and Karl Wegmann},
doi = {10.1007/s10346-022-01862-2},
year = {2022},
date = {2022-08-25},
urldate = {2022-08-25},
journal = {Landslides},
volume = {19},
number = {6},
pages = {1297-1319},
abstract = {How debris flows erode and deposit material along their paths is difficult to determine in natural settings due to the lack of warning and the rapid pace at which they occur. Post-event field measurements or controlled flume experi-ments are commonly used to evaluate debris flows between the head and the distalmost deposit. Increasingly available high-resolution lidar data provide another means to evaluate the entrainment and deposition of material during a debris flow. This study utilizes submeter lidar before and after a debris flow event in Polk County, North Carolina, to evaluate for volumet-ric growth and decay of 54 rainfall-triggered debris flows that occurred during a convective storm on May 18, 2018. Debris flow evolution can be characterized by three discrete phases when viewed according to a volume-distance plot: (1) the initiating debris slide, (2) the entrainment phase, and (3) the depositional phase. The rate of debris flow growth is highest during the first phase, nearly linear during the second, and negative during the third phase. When normalized by distance along the flow, the growth rate decays according to a power law E=aXb ( r2≥0.97 ) . This new power law relationship may indicate differences in initiating landslide process and should be leveraged in future runout modeling studies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
How debris flows erode and deposit material along their paths is difficult to determine in natural settings due to the lack of warning and the rapid pace at which they occur. Post-event field measurements or controlled flume experi-ments are commonly used to evaluate debris flows between the head and the distalmost deposit. Increasingly available high-resolution lidar data provide another means to evaluate the entrainment and deposition of material during a debris flow. This study utilizes submeter lidar before and after a debris flow event in Polk County, North Carolina, to evaluate for volumet-ric growth and decay of 54 rainfall-triggered debris flows that occurred during a convective storm on May 18, 2018. Debris flow evolution can be characterized by three discrete phases when viewed according to a volume-distance plot: (1) the initiating debris slide, (2) the entrainment phase, and (3) the depositional phase. The rate of debris flow growth is highest during the first phase, nearly linear during the second, and negative during the third phase. When normalized by distance along the flow, the growth rate decays according to a power law E=aXb ( r2≥0.97 ) . This new power law relationship may indicate differences in initiating landslide process and should be leveraged in future runout modeling studies.
Chou, Alan; Brachman, Richard; Rowe, Kerry
Leakage Through a Hole in a Geomembrane Beneath a Fine-Grained tailings Journal Article
In: Canadian Geotechnical Journal, vol. 59, no. 3, pp. 372-383, 2022.
@article{article1,
title = {Leakage Through a Hole in a Geomembrane Beneath a Fine-Grained tailings},
author = {Alan Chou and Richard Brachman and Kerry Rowe},
doi = {10.1139/cgj-2020-0289},
year = {2022},
date = {2022-07-28},
urldate = {2022-07-26},
journal = {Canadian Geotechnical Journal},
volume = {59},
number = {3},
pages = {372-383},
abstract = {Leakage through a 10-mm-diameter hole in a geomembrane beneath fine-grained tailings is examined for a range of pore pressures and effective stresses. Leakage was measured in an experiment with coupled physical and hydraulic conditions to simulate the effective stresses and flow conditions near the hole. The leakage rate was at little as 0.16 L/day with 200 kPa pore pressure (10-30 kPa effective stresses) and increased only to 0.46 L/day with 800 kPa pore pressure (200 kPa effective stress). Seepage analysis of the experiment and local measurements of permeability from small samples extracted after the experiment indicate that the tailings hydraulic conductivity controlling flow was 3–6 x10-9 m/s. Only a subtle decrease in hydraulic conductivity (less than 2 times) near the hole was found. No evidence of seepage induced migration of fines within the tailings was found. Calculations with the parameters deduced from the experiment show that leakage from a tailings storage facilities containing fine-grained tailings can be limited to 1-2 L/ha/day with a geomembrane liner, even when containing up to five 10-mm-diameter holes per hectare, as opposed to an unlined facility with 3 to 4 orders of magnitude more leakage.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Leakage through a 10-mm-diameter hole in a geomembrane beneath fine-grained tailings is examined for a range of pore pressures and effective stresses. Leakage was measured in an experiment with coupled physical and hydraulic conditions to simulate the effective stresses and flow conditions near the hole. The leakage rate was at little as 0.16 L/day with 200 kPa pore pressure (10-30 kPa effective stresses) and increased only to 0.46 L/day with 800 kPa pore pressure (200 kPa effective stress). Seepage analysis of the experiment and local measurements of permeability from small samples extracted after the experiment indicate that the tailings hydraulic conductivity controlling flow was 3–6 x10-9 m/s. Only a subtle decrease in hydraulic conductivity (less than 2 times) near the hole was found. No evidence of seepage induced migration of fines within the tailings was found. Calculations with the parameters deduced from the experiment show that leakage from a tailings storage facilities containing fine-grained tailings can be limited to 1-2 L/ha/day with a geomembrane liner, even when containing up to five 10-mm-diameter holes per hectare, as opposed to an unlined facility with 3 to 4 orders of magnitude more leakage.
Feigl, Moritz; Roesky, Benjamin; Herrnegger, Mathew; Schulz, Karsten; Hayashi, Masaki
Learning From Mistakes - Assessing the Performance and Uncertainty in Process-Based Models Journal Article
In: Hydrological Processes, vol. 36, no. 2, 2022.
@article{article1,
title = {Learning From Mistakes - Assessing the Performance and Uncertainty in Process-Based Models},
author = {Moritz Feigl and Benjamin Roesky and Mathew Herrnegger and Karsten Schulz and Masaki Hayashi},
doi = {10.1002/hyp.14515},
year = {2022},
date = {2022-07-26},
urldate = {2022-07-24},
journal = {Hydrological Processes},
volume = {36},
number = {2},
abstract = {Typical applications of process- or physically-based models aim to gain a better process understanding or provide the basis for a decision-making process. To adequately represent the physical system, models should include all essential processes. However, model errors can still occur. Other than large systematic observation errors, simplified, misrepresented, inadequately parametrized or missing processes are potential sources of errors. This study presents a set of methods and a proposed workflow for analyzing errors of process-based models as a basis for relating them to process representations. The evaluated approach consists of three steps: (i) training a machine learning (ML) error-model using the input data of the process-based model and other available variables, (ii) estimation of local explanations (i.e., contributions of each variable to a individual prediction) for each predicted model error using SHapley Additive exPlanations (SHAP) in combination with principal component analysis, (iii) clustering of SHAP values of all predicted errors to derive groups with similar error generation characteristics. By analyzing these groups of different error-variable association, hypotheses on error generation and corresponding processes can be formulated. That can ultimately lead to improvements in process understanding and prediction. The approach is applied to a process-based stream water temperature model HFLUX in a case study for modelling an alpine stream in the Canadian Rocky Mountains. By using available meteorological and hydrological variables as inputs, the applied ML model is able to predict model residuals. Clustering of SHAP values results in three distinct error groups that are mainly related to shading and vegetation emitted longwave radiation. Model errors are rarely random and often contain valuable information. Assessing model error associations is ultimately a way of enhancing trust in implemented processes and of providing information on potential areas of improvement to the model.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Typical applications of process- or physically-based models aim to gain a better process understanding or provide the basis for a decision-making process. To adequately represent the physical system, models should include all essential processes. However, model errors can still occur. Other than large systematic observation errors, simplified, misrepresented, inadequately parametrized or missing processes are potential sources of errors. This study presents a set of methods and a proposed workflow for analyzing errors of process-based models as a basis for relating them to process representations. The evaluated approach consists of three steps: (i) training a machine learning (ML) error-model using the input data of the process-based model and other available variables, (ii) estimation of local explanations (i.e., contributions of each variable to a individual prediction) for each predicted model error using SHapley Additive exPlanations (SHAP) in combination with principal component analysis, (iii) clustering of SHAP values of all predicted errors to derive groups with similar error generation characteristics. By analyzing these groups of different error-variable association, hypotheses on error generation and corresponding processes can be formulated. That can ultimately lead to improvements in process understanding and prediction. The approach is applied to a process-based stream water temperature model HFLUX in a case study for modelling an alpine stream in the Canadian Rocky Mountains. By using available meteorological and hydrological variables as inputs, the applied ML model is able to predict model residuals. Clustering of SHAP values results in three distinct error groups that are mainly related to shading and vegetation emitted longwave radiation. Model errors are rarely random and often contain valuable information. Assessing model error associations is ultimately a way of enhancing trust in implemented processes and of providing information on potential areas of improvement to the model.
Zellman, Mark; Lifton, Zach; DuRoss, Christopher; Thackray, Glenn
Lidar Data Reveal New Faults in the Epicentral Region of the 2020 M 6.5 Stanley, Idaho Earthquake Journal Article
In: Seismological Research Letters, 2022.
@article{journal1,
title = {Lidar Data Reveal New Faults in the Epicentral Region of the 2020 M 6.5 Stanley, Idaho Earthquake },
author = {Mark Zellman and Zach Lifton and Christopher DuRoss and Glenn Thackray},
doi = {10.1785/0220220087},
year = {2022},
date = {2022-07-24},
urldate = {2022-07-24},
journal = {Seismological Research Letters},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Froese, Corey; Engelbrecht, Jeanine
Linking Satellite InSAR Ground Deformation Data into Operational Decision Conference
Research Exchange Meeting, 2022.
@conference{Conference1,
title = {Linking Satellite InSAR Ground Deformation Data into Operational Decision},
author = {Corey Froese and Jeanine Engelbrecht},
year = {2022},
date = {2022-07-22},
urldate = {2022-07-24},
booktitle = {Research Exchange Meeting},
abstract = {Mature geohazards management programs assess information related to ground movement hazards, such as landslides or subsidence, in conjunction with the condition of the pipeline (vulnerability). This enables the development of site-specific risk rankings and intervention strategies along extensive networks of pipeline infrastructure. As technology and software tools have evolved, pipeline operators are better able to leverage spatial data from a variety of ground and remote-sensed data for improved understanding of the hazard. Remote sensing data can be used to identify potential geohazard features, monitor known geohazard sites, and assess the rate of ground displacement. When combined with geotechnical subject matter expert (SME) knowledge of ground conditions, gained through desktop assessments, field inspections, and analysis of in-line inspection tool data for example, remote sensing data can inform the prioritization of next actions. Over the past few years, many pipeline operators have been purchasing InSAR data and are looking to better utilize this data to support their decision-making processes. This paper will provide an overview of how InSAR data may be integrated into geohazard management programs and how that data can be linked a to site-based risk classification to determine the timing of operational actions and possible interventions.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Mature geohazards management programs assess information related to ground movement hazards, such as landslides or subsidence, in conjunction with the condition of the pipeline (vulnerability). This enables the development of site-specific risk rankings and intervention strategies along extensive networks of pipeline infrastructure. As technology and software tools have evolved, pipeline operators are better able to leverage spatial data from a variety of ground and remote-sensed data for improved understanding of the hazard. Remote sensing data can be used to identify potential geohazard features, monitor known geohazard sites, and assess the rate of ground displacement. When combined with geotechnical subject matter expert (SME) knowledge of ground conditions, gained through desktop assessments, field inspections, and analysis of in-line inspection tool data for example, remote sensing data can inform the prioritization of next actions. Over the past few years, many pipeline operators have been purchasing InSAR data and are looking to better utilize this data to support their decision-making processes. This paper will provide an overview of how InSAR data may be integrated into geohazard management programs and how that data can be linked a to site-based risk classification to determine the timing of operational actions and possible interventions.
Rousseau, Prasanna; Sivathayalan, Siva
Liquefaction of Sands Subjected to Principal Stress Rotation Caused by Generalized Seismic Loading Journal Article
In: Canadian Geotechnical Journal, 2022.
@article{article1,
title = {Liquefaction of Sands Subjected to Principal Stress Rotation Caused by Generalized Seismic Loading },
author = {Prasanna Rousseau and Siva Sivathayalan},
doi = {10.1139/cgj-2021-0035},
year = {2022},
date = {2022-07-13},
urldate = {2022-07-06},
journal = {Canadian Geotechnical Journal},
abstract = {A comprehensive experimental study that quantifies the influence of coupled compression and shear wave loading on liquefaction susceptibility of sands is presented. Such loading leads to complex principal stress rotation, which in turn impacts the potential for liquefaction in soils even if the cyclic loading intensity remains constant. The nature and degree of principal stress rotation caused by coupled loading are significantly influenced by the initial consolidation stress state, and the cyclic shear (ΔS), cyclic normal (ΔN) stress increments, the ratio ∆S⁄∆N, and the phase shift (δ) between the waves. Cyclic hollow cylinder torsional shear tests were carried out on Fraser River sand specimens isotropically consolidated to different σ'mc and subjected to coupled cyclic loading with representative ∆S⁄∆N. For a given CSR and initial σ'mc, the liquefaction resistance decreases with increasing s(𝛿) wave intensity relative to p-wave intensity, which are proxies to stress increments ΔS and ΔN respectively. Liquefaction resistance decreases with an increase in ∆S⁄∆N up to a limiting value of about 2 beyond which increasing ∆S⁄∆N does not significantly influence the cyclic resistance. The finding that cyclic resistance ratio CRR decreases with increasing ΔS⁄ΔN is consistent with the understanding that the cyclic resistance is lower under simple shear loading mode compared to triaxial shear. This indicates that the Kσ factor can be considered even under generalized coupled loading conditions.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A comprehensive experimental study that quantifies the influence of coupled compression and shear wave loading on liquefaction susceptibility of sands is presented. Such loading leads to complex principal stress rotation, which in turn impacts the potential for liquefaction in soils even if the cyclic loading intensity remains constant. The nature and degree of principal stress rotation caused by coupled loading are significantly influenced by the initial consolidation stress state, and the cyclic shear (ΔS), cyclic normal (ΔN) stress increments, the ratio ∆S⁄∆N, and the phase shift (δ) between the waves. Cyclic hollow cylinder torsional shear tests were carried out on Fraser River sand specimens isotropically consolidated to different σ'mc and subjected to coupled cyclic loading with representative ∆S⁄∆N. For a given CSR and initial σ'mc, the liquefaction resistance decreases with increasing s(𝛿) wave intensity relative to p-wave intensity, which are proxies to stress increments ΔS and ΔN respectively. Liquefaction resistance decreases with an increase in ∆S⁄∆N up to a limiting value of about 2 beyond which increasing ∆S⁄∆N does not significantly influence the cyclic resistance. The finding that cyclic resistance ratio CRR decreases with increasing ΔS⁄ΔN is consistent with the understanding that the cyclic resistance is lower under simple shear loading mode compared to triaxial shear. This indicates that the Kσ factor can be considered even under generalized coupled loading conditions.
Ostenaa, Dean; Zellman, Mark; Morgan, Matthew; DuRoss, Christopher; Briggs, Richard; Gold, Ryan; Mahan, Shannon; Gray, Harrison; Broes, Lauren; Lindsey, Kassandra
Mid- to Late-Quaternary Geomorphic and Paleoseismic Event History, Cheraw Fault, Southeastern Colorado Journal Article
In: Bulletin of the Seismological Society of America, 2022.
@article{article1,
title = {Mid- to Late-Quaternary Geomorphic and Paleoseismic Event History, Cheraw Fault, Southeastern Colorado},
author = {Dean Ostenaa and Mark Zellman and Matthew Morgan and Christopher DuRoss and Richard Briggs and Ryan Gold and Shannon Mahan and Harrison Gray and Lauren Broes and Kassandra Lindsey},
doi = {10.1785/0120210285},
year = {2022},
date = {2022-06-24},
urldate = {2022-06-24},
journal = {Bulletin of the Seismological Society of America},
abstract = {Despite its subdued expression and isolated location within the Great Plains of southeastern Colorado, the 80 km long Cheraw fault may be one of the most active faults in North America east of the Rocky Mountains. We present geomorphic analyses, geochronology, and paleoseismic trenching data to (1) document the rupture history of the ∼45 km long southwestern section of the Cheraw fault over the past ∼19 ka, and (2) evaluate slip rate changes for the entire fault over the past ∼200 ka. Results from new trenches excavated at the Old Ranch site show evidence of four surface rupture events since ∼19 ka, each with an average vertical displacement of 0.75 ± 0.15 m. An additional event is likely only slightly older than ∼19 ka. Evidence for relatively small displacements at and near the Old Ranch site indicates that most of these earthquakes were magnitude (M) 7 or less and likely did not rupture the full length of the Cheraw fault. Since ∼19 ka, the average slip rate is ∼0.16 ± 0.3 mm/yr near the Old Ranch site with an average interevent time of 3–5 ka. New geochronologic data for mid‐ to late‐Quaternary geomorphic surfaces cut by the Cheraw fault imply rapid incision by local Arkansas River tributaries from ∼145 to ∼100 ka. Maximum vertical offsets of 7–9 m for these surfaces indicate that from ∼19 to >200 ka the average slip rate was no greater than ∼0.03 mm/yr. The accelerated slip rate since ∼19 ka indicates a possible response to rapid erosional unloading and/or a limited late Cenozoic, <40 ka, paleoseismic history for the Cheraw fault.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Despite its subdued expression and isolated location within the Great Plains of southeastern Colorado, the 80 km long Cheraw fault may be one of the most active faults in North America east of the Rocky Mountains. We present geomorphic analyses, geochronology, and paleoseismic trenching data to (1) document the rupture history of the ∼45 km long southwestern section of the Cheraw fault over the past ∼19 ka, and (2) evaluate slip rate changes for the entire fault over the past ∼200 ka. Results from new trenches excavated at the Old Ranch site show evidence of four surface rupture events since ∼19 ka, each with an average vertical displacement of 0.75 ± 0.15 m. An additional event is likely only slightly older than ∼19 ka. Evidence for relatively small displacements at and near the Old Ranch site indicates that most of these earthquakes were magnitude (M) 7 or less and likely did not rupture the full length of the Cheraw fault. Since ∼19 ka, the average slip rate is ∼0.16 ± 0.3 mm/yr near the Old Ranch site with an average interevent time of 3–5 ka. New geochronologic data for mid‐ to late‐Quaternary geomorphic surfaces cut by the Cheraw fault imply rapid incision by local Arkansas River tributaries from ∼145 to ∼100 ka. Maximum vertical offsets of 7–9 m for these surfaces indicate that from ∼19 to >200 ka the average slip rate was no greater than ∼0.03 mm/yr. The accelerated slip rate since ∼19 ka indicates a possible response to rapid erosional unloading and/or a limited late Cenozoic, <40 ka, paleoseismic history for the Cheraw fault.
Arenson, Lukas; Harrington, Jordan; Koenig, Cassandra; Wainstein, Pablo
Mountain Permafrost Hydrology—A Practical Review Following Studies from the Andes Journal Article
In: Geosciences, vol. 12, no. 2, 2022.
@article{article1,
title = {Mountain Permafrost Hydrology—A Practical Review Following Studies from the Andes},
author = {Lukas Arenson and Jordan Harrington and Cassandra Koenig and Pablo Wainstein },
doi = {10.3390/geosciences12020048},
year = {2022},
date = {2022-06-15},
urldate = {2022-01-20},
journal = {Geosciences},
volume = {12},
number = {2},
abstract = {Climate change is expected to reduce water security in arid mountain regions around the world. Vulnerable water supplies in semi-arid zones, such as the Dry Andes, are projected to be further stressed through changes in air temperature, precipitation patterns, sublimation, and evapotranspiration. Together with glacier recession this will negatively impact water availability. While glacier hydrology has been the focus of scientific research for a long time, relatively little is known about the hydrology of mountain permafrost. In contrast to glaciers, where ice is at the surface and directly affected by atmospheric conditions, the behaviour of permafrost and ground ice is more complex, as other factors, such as variable surficial sediments, vegetation cover, or shallow groundwater flow, influence heat transfer and time scales over which changes occur. The effects of permafrost on water flow paths have been studied in lowland areas, with limited research in the mountains. An understanding of how permafrost degradation and associated melt of ground ice (where present) contribute to streamflow in mountain regions is still lacking. Mountain permafrost, particularly rock glaciers, is often conceptualized as a (frozen) water reservoir; however, rates of permafrost ground ice melt and the contribution to water budgets are rarely considered. Additionally, ground ice and permafrost are not directly visible at the surface; hence, uncertainties related to their three-dimensional extent are orders of magnitude higher than those for glaciers. Ground ice volume within permafrost must always be approximated, further complicating estimations of its response to climate change. This review summarizes current understanding of mountain permafrost hydrology, discusses challenges and limitations, and provides suggestions for areas of future research, using the Dry Andes as a basis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Climate change is expected to reduce water security in arid mountain regions around the world. Vulnerable water supplies in semi-arid zones, such as the Dry Andes, are projected to be further stressed through changes in air temperature, precipitation patterns, sublimation, and evapotranspiration. Together with glacier recession this will negatively impact water availability. While glacier hydrology has been the focus of scientific research for a long time, relatively little is known about the hydrology of mountain permafrost. In contrast to glaciers, where ice is at the surface and directly affected by atmospheric conditions, the behaviour of permafrost and ground ice is more complex, as other factors, such as variable surficial sediments, vegetation cover, or shallow groundwater flow, influence heat transfer and time scales over which changes occur. The effects of permafrost on water flow paths have been studied in lowland areas, with limited research in the mountains. An understanding of how permafrost degradation and associated melt of ground ice (where present) contribute to streamflow in mountain regions is still lacking. Mountain permafrost, particularly rock glaciers, is often conceptualized as a (frozen) water reservoir; however, rates of permafrost ground ice melt and the contribution to water budgets are rarely considered. Additionally, ground ice and permafrost are not directly visible at the surface; hence, uncertainties related to their three-dimensional extent are orders of magnitude higher than those for glaciers. Ground ice volume within permafrost must always be approximated, further complicating estimations of its response to climate change. This review summarizes current understanding of mountain permafrost hydrology, discusses challenges and limitations, and provides suggestions for areas of future research, using the Dry Andes as a basis.
Reid, David; Dickinson, Simon; Mital, Utkarsh; Fanni, Riccardo; Fourie, Andy
On Some Uncertainties Related to Static Liquefaction Triggering Assessments Journal Article
In: Proceedings of the Institution of Civil Engineers: Geotechnical Engineering, vol. 175, no. 2, pp. 181-199, 2022.
@article{article1,
title = {On Some Uncertainties Related to Static Liquefaction Triggering Assessments},
author = {David Reid and Simon Dickinson and Utkarsh Mital and Riccardo Fanni and Andy Fourie},
doi = {10.1680/jgeen.21.00054},
year = {2022},
date = {2022-05-28},
urldate = {2022-05-28},
journal = {Proceedings of the Institution of Civil Engineers: Geotechnical Engineering},
volume = {175},
number = {2},
pages = {181-199},
abstract = {Static liquefaction has been identified as the cause of several recent tailings storage facility (TSF) failures. Partially based on the investigations carried out, significant advances on the analysis of static liquefaction triggering have been made. This includes application of critical state-based models in a stress-deformation framework to identify if in situ conditions are approaching a level where triggering could occur. However, several important uncertainties remain. The current work investigates three of these uncertainties and their effect (both independently, and in conjunction) on the identification of static liquefaction triggering and slope failure: geostatic stress ratio K0, intermediate principal stress ratio, and principal stress angle from vertical. These uncertainties are examined through a series of numerical analyses of an idealised TSF. Various values of K0 are used to examine their effect on triggering, while different approaches to the potential effect of intermediate principal stress ratio and principal stress angle from vertical on instability are taken. This work shows that current state of knowledge in these areas is such that significant uncertainty seems unavoidable in attempting to identify exactly when a particular slope may undergo static liquefaction triggering. Experimental and in situ test programs that may be useful in reducing this uncertainty are outlined.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Static liquefaction has been identified as the cause of several recent tailings storage facility (TSF) failures. Partially based on the investigations carried out, significant advances on the analysis of static liquefaction triggering have been made. This includes application of critical state-based models in a stress-deformation framework to identify if in situ conditions are approaching a level where triggering could occur. However, several important uncertainties remain. The current work investigates three of these uncertainties and their effect (both independently, and in conjunction) on the identification of static liquefaction triggering and slope failure: geostatic stress ratio K0, intermediate principal stress ratio, and principal stress angle from vertical. These uncertainties are examined through a series of numerical analyses of an idealised TSF. Various values of K0 are used to examine their effect on triggering, while different approaches to the potential effect of intermediate principal stress ratio and principal stress angle from vertical on instability are taken. This work shows that current state of knowledge in these areas is such that significant uncertainty seems unavoidable in attempting to identify exactly when a particular slope may undergo static liquefaction triggering. Experimental and in situ test programs that may be useful in reducing this uncertainty are outlined.
Sharma, Keshab; Bin, Jia; Deng, Lijun
Performance-Based Seismic Design of Rocking Shallow Foundations in Cohesive Soil: Methodology and Numerical Validation Journal Article
In: Soil Dynamics and Earthquake Engineering, vol. 159, 2022.
@article{article1,
title = {Performance-Based Seismic Design of Rocking Shallow Foundations in Cohesive Soil: Methodology and Numerical Validation},
author = {Keshab Sharma and Jia Bin and Lijun Deng},
doi = {10.1016/j.soildyn.2022.107244},
year = {2022},
date = {2022-05-21},
urldate = {2022-05-26},
journal = {Soil Dynamics and Earthquake Engineering},
volume = {159},
abstract = {The concept of rocking shallow foundation as a base isolation mechanism has been incorporated into seismic design guidelines, but a feasible design method is yet to be developed. This research proposes a performance-based seismic design (PBSD) for bridges supported on rocking shallow foundations in cohesive soils. This PBSD considers three performance indicators: maximum drift, residual footing rotation and residual settlement. Empirical correlations to obtain the secant stiffness, hysteresis damping ratios, re-centering ratio and residual settlement were obtained from preceding field tests. The PBSD was elaborated with two examples for which the shallow foundation of an as-built highway overpass bridge was re-designed in two presumed cohesive soil sites. The performance of the re-designed bridge was further verified using nonlinear time history analyses. A numerical model was developed, calibrated, and validated using field test results. The maximum and residual drifts and residual footing settlement at the design level earthquakes obtained from numerical modeling were shown to satisfy the performance criteria.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The concept of rocking shallow foundation as a base isolation mechanism has been incorporated into seismic design guidelines, but a feasible design method is yet to be developed. This research proposes a performance-based seismic design (PBSD) for bridges supported on rocking shallow foundations in cohesive soils. This PBSD considers three performance indicators: maximum drift, residual footing rotation and residual settlement. Empirical correlations to obtain the secant stiffness, hysteresis damping ratios, re-centering ratio and residual settlement were obtained from preceding field tests. The PBSD was elaborated with two examples for which the shallow foundation of an as-built highway overpass bridge was re-designed in two presumed cohesive soil sites. The performance of the re-designed bridge was further verified using nonlinear time history analyses. A numerical model was developed, calibrated, and validated using field test results. The maximum and residual drifts and residual footing settlement at the design level earthquakes obtained from numerical modeling were shown to satisfy the performance criteria.
McClymont, Alastair; Bauman, Paul; Freund, Richard; Seligman, Jon; Jol, Harry; Reeder, Philip; Benismon, Ken; Vengalis, Rokas
Preserving Holocaust History: Geophysical Investigations at the Ponary (Paneriai) Extermination Site Journal Article
In: Geophysics, vol. 87, no. 1, 2022.
@article{article1,
title = {Preserving Holocaust History: Geophysical Investigations at the Ponary (Paneriai) Extermination Site},
author = {Alastair McClymont and Paul Bauman and Richard Freund and Jon Seligman and Harry Jol and Philip Reeder and Ken Benismon and Rokas Vengalis},
doi = {10.1190/geo2021-0065.1},
year = {2022},
date = {2022-05-18},
urldate = {2022-05-20},
journal = {Geophysics},
volume = {87},
number = {1},
abstract = {Holocaust mass grave sites in eastern Europe can be difficult to investigate due to a paucity of historical documentation relating to the events and because the use of traditional invasive archaeology methods raises concerns around the disturbance of the remains of Jewish people. When combined with other lines of evidence, including historic photos and eyewitness testimony, noninvasive geophysical methods help to effectively identify and demarcate buried features at Holocaust sites, limiting unnecessary excavations. Between 1941 and 1944, as many as 100,000 people were murdered at the Ponary (Paneriai) extermination site in Lithuania, but many critical details of the site layout during this period are still to be resolved, including the location of some of the mass graves and confirmation of an escape tunnel that was used by slave laborers to escape captivity and certain death at the site. At Ponary, a combination of electrical resistivity tomography (ERT) profiling, limited ground-penetrating radar data, and bare-earth elevation data (from a light and distance ranging data set) was used to confirm the location of a large unmarked mass grave with a diameter of approximately 25 m and depth of approximately 4 m. Additional ERT profiling at a second location imaged the entrance to an escape tunnel previously uncovered by an archaeological excavation in 2004, and it detected an approximately 5 m section of the continuation of the tunnel, approximately 33 m away from the tunnel entrance. The geophysical results are supported by evidence from limited archaeological excavations, historical photographs, eyewitness descriptions of the site layout, and testimonies from the few survivors who managed to escape Ponary.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Holocaust mass grave sites in eastern Europe can be difficult to investigate due to a paucity of historical documentation relating to the events and because the use of traditional invasive archaeology methods raises concerns around the disturbance of the remains of Jewish people. When combined with other lines of evidence, including historic photos and eyewitness testimony, noninvasive geophysical methods help to effectively identify and demarcate buried features at Holocaust sites, limiting unnecessary excavations. Between 1941 and 1944, as many as 100,000 people were murdered at the Ponary (Paneriai) extermination site in Lithuania, but many critical details of the site layout during this period are still to be resolved, including the location of some of the mass graves and confirmation of an escape tunnel that was used by slave laborers to escape captivity and certain death at the site. At Ponary, a combination of electrical resistivity tomography (ERT) profiling, limited ground-penetrating radar data, and bare-earth elevation data (from a light and distance ranging data set) was used to confirm the location of a large unmarked mass grave with a diameter of approximately 25 m and depth of approximately 4 m. Additional ERT profiling at a second location imaged the entrance to an escape tunnel previously uncovered by an archaeological excavation in 2004, and it detected an approximately 5 m section of the continuation of the tunnel, approximately 33 m away from the tunnel entrance. The geophysical results are supported by evidence from limited archaeological excavations, historical photographs, eyewitness descriptions of the site layout, and testimonies from the few survivors who managed to escape Ponary.
Deen, Sean; Hendry, Jim; Barbour, Lee; Das, Soumya; Essilfie-Dughan, Joseph
In: Geochemistry, 2022.
@article{article1,
title = {Removal of Dissolved Selenium by Siderite, Pyrite, and Sphalerite: Implications to Selenium Sequestration in Water-Saturated, Anoxic Coal Waste Rock},
author = {Sean Deen and Jim Hendry and Lee Barbour and Soumya Das and Joseph Essilfie-Dughan},
doi = {10.1016/j.chemer.2022.125863},
year = {2022},
date = {2022-04-13},
urldate = {2022-02-20},
journal = {Geochemistry},
abstract = {The mechanisms of abiotic sequestration of Se(VI) and Se(IV) on a sample of coal waste rock collected from the Elk Valley, Canada and on three pure mineral species (i.e., siderite, pyrite, and sphalerite) present in coal waste rock were assessed using sterile batch testing under water-saturated, anoxic conditions. Only siderite removed measurable Se(VI) from the test solutions with ~90% removal after 100 d attributed to initial adsorption to the siderite surface as Se(VI) and subsequent reduction to Se(IV) and Se(0). In contrast to Se(VI), all samples removed Se(IV) from the aqueous solutions. The rate of Se(IV) removal was pyrite > siderite > waste rock > sphalerite. The waste rock sample removed Se(IV) from solution in two stages: up to ~40% of the aqueous Se(IV) was rapidly removed (by day 1) followed by slower removal of Se(IV) with up to ~97% removal after 99 d. Se(IV) removal is attributed to the adsorption of Se(IV) and subsequent reduction to Se(0) onto the siderite and pyrite phases of the waste rock. The initial (1 d) removal of Se(IV) by waste rock was characterized using a distribution coefficient (Kd) of 15.5 L/kg. Longer-term Se(IV) removal was fitted with zero and first order removal rates. The removal of Se(IV) by sphalerite was minor and deemed to have a minimal effect on Se sequestration in the waste rock. Desorption tests on waste rock showed that the fraction of sequestered Se susceptible to desorption decreased with time as adsorbed Se(IV) was reduced to insoluble Se(0). These findings show that abiotic Se sequestration can occur in saturated, anoxic zones in coal waste rock dumps.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The mechanisms of abiotic sequestration of Se(VI) and Se(IV) on a sample of coal waste rock collected from the Elk Valley, Canada and on three pure mineral species (i.e., siderite, pyrite, and sphalerite) present in coal waste rock were assessed using sterile batch testing under water-saturated, anoxic conditions. Only siderite removed measurable Se(VI) from the test solutions with ~90% removal after 100 d attributed to initial adsorption to the siderite surface as Se(VI) and subsequent reduction to Se(IV) and Se(0). In contrast to Se(VI), all samples removed Se(IV) from the aqueous solutions. The rate of Se(IV) removal was pyrite > siderite > waste rock > sphalerite. The waste rock sample removed Se(IV) from solution in two stages: up to ~40% of the aqueous Se(IV) was rapidly removed (by day 1) followed by slower removal of Se(IV) with up to ~97% removal after 99 d. Se(IV) removal is attributed to the adsorption of Se(IV) and subsequent reduction to Se(0) onto the siderite and pyrite phases of the waste rock. The initial (1 d) removal of Se(IV) by waste rock was characterized using a distribution coefficient (Kd) of 15.5 L/kg. Longer-term Se(IV) removal was fitted with zero and first order removal rates. The removal of Se(IV) by sphalerite was minor and deemed to have a minimal effect on Se sequestration in the waste rock. Desorption tests on waste rock showed that the fraction of sequestered Se susceptible to desorption decreased with time as adsorbed Se(IV) was reduced to insoluble Se(0). These findings show that abiotic Se sequestration can occur in saturated, anoxic zones in coal waste rock dumps.
Wooten, Richard; Scheip, Corey; Hill, Jesse; Douglas, Thomas; Korte, David; Cattanach, Bart; Bozdog, Nicholas; Isard, Sierra
Response to Landslides and Landslide Mapping on the Blue Ridge Escarpment, Polk County, North Carolina, USA Journal Article
In: Environmental and Engineering Geoscience, vol. 28, no. 1, pp. 25-54, 2022.
@article{article1,
title = { Response to Landslides and Landslide Mapping on the Blue Ridge Escarpment, Polk County, North Carolina, USA},
author = {Richard Wooten and Corey Scheip and Jesse Hill and Thomas Douglas and David Korte and Bart Cattanach and Nicholas Bozdog and Sierra Isard },
doi = {10.2113/EEG-D-21-00022},
year = {2022},
date = {2022-04-10},
urldate = {2022-04-28},
journal = {Environmental and Engineering Geoscience},
volume = {28},
number = {1},
pages = {25-54},
abstract = {Landslides occur in Polk County, North Carolina, primarily along the Columbus Promontory of Blue Ridge Escarpment (BRE), which has 400 m of topographic relief and slopes typically >20°. Bedrock is characterized as late Proterozoic to early Paleozoic metamorphic rocks within Paleozoic thrust sheets. On May 18, 2018, ∼200 mm of rainfall over a 3- to 4-hour period triggered numerous debris flows and slides along the BRE, causing one fatality and severe damage to homes and roads. The State Emergency Operations Center tasked the North Carolina Geological Survey to assess slope stability ahead of search and rescue operations and assess damage along the North Pacolet River valley. The loss of life and destruction from the 2018 storm and ongoing threats to infrastructure prompted us to map landslides throughout Polk County in 2019–2021 to fully document the 2018 landslides and place them in the context of past and ongoing landsliding. We mapped 920 varied types of landslides and attribute 241 to the 2018 storm, making it one of the largest events in North Carolina since 2004 with respect to landslide numbers and spatial frequency. The highest concentrations of landslide features in Polk County are along the slopes of the BRE, especially the Pacolet River and Green River valleys. These rivers exploit post-orogenic brittle fractures to form linear reentrants where the May 2018 and other landslides are concentrated. This article describes our landslide response and mapping efforts and relates our findings to the geomorphic and geologic framework and to past landslide events in the region.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Landslides occur in Polk County, North Carolina, primarily along the Columbus Promontory of Blue Ridge Escarpment (BRE), which has 400 m of topographic relief and slopes typically >20°. Bedrock is characterized as late Proterozoic to early Paleozoic metamorphic rocks within Paleozoic thrust sheets. On May 18, 2018, ∼200 mm of rainfall over a 3- to 4-hour period triggered numerous debris flows and slides along the BRE, causing one fatality and severe damage to homes and roads. The State Emergency Operations Center tasked the North Carolina Geological Survey to assess slope stability ahead of search and rescue operations and assess damage along the North Pacolet River valley. The loss of life and destruction from the 2018 storm and ongoing threats to infrastructure prompted us to map landslides throughout Polk County in 2019–2021 to fully document the 2018 landslides and place them in the context of past and ongoing landsliding. We mapped 920 varied types of landslides and attribute 241 to the 2018 storm, making it one of the largest events in North Carolina since 2004 with respect to landslide numbers and spatial frequency. The highest concentrations of landslide features in Polk County are along the slopes of the BRE, especially the Pacolet River and Green River valleys. These rivers exploit post-orogenic brittle fractures to form linear reentrants where the May 2018 and other landslides are concentrated. This article describes our landslide response and mapping efforts and relates our findings to the geomorphic and geologic framework and to past landslide events in the region.
Acharya, Prabin; Sharma, Keshab; Pokharel, Govind; Adhikari, Rachana
Reviewing the Progress of Reconstruction Five Years After the 2015 Gorkha Earthquake, Nepal Journal Article
In: Building Research & Information, 2022.
@article{journal1c,
title = {Reviewing the Progress of Reconstruction Five Years After the 2015 Gorkha Earthquake, Nepal },
author = {Prabin Acharya and Keshab Sharma and Govind Pokharel and Rachana Adhikari},
doi = {10.1080/09613218.2022.2043139},
year = {2022},
date = {2022-04-06},
journal = {Building Research & Information},
abstract = {An earthquake of moment magnitude (Mw) 7.8, the largest in the last 80 years, struck central Nepal on April 25, 2015. Named the Gorkha earthquake, it wreaked havoc on the country’s central region, affecting 32 of 77 districts. The earthquake impacted nearly a million private houses, thousands of educational infrastructures, hundreds of health facilities, myriad cultural heritages and many other infrastructures. The National Reconstruction Authority (NRA) was established to lead the post-earthquake recovery and reconstruction and complete it within five years. This paper presents details of the earthquake’s effects, the early response and the status of the post-earthquake reconstruction progress five years after the earthquake. Official reports from Nepalese government institutions, national and international authorities, government databases and research papers on the Gorkha earthquake were reviewed. The numbers of various infrastructures reconstructed and under construction each year after the earthquake and the reconstruction processes adopted are presented. The results show that 67% of private houses, 74% of educational institutions and 58% of health facilities were reconstructed in the five years.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An earthquake of moment magnitude (Mw) 7.8, the largest in the last 80 years, struck central Nepal on April 25, 2015. Named the Gorkha earthquake, it wreaked havoc on the country’s central region, affecting 32 of 77 districts. The earthquake impacted nearly a million private houses, thousands of educational infrastructures, hundreds of health facilities, myriad cultural heritages and many other infrastructures. The National Reconstruction Authority (NRA) was established to lead the post-earthquake recovery and reconstruction and complete it within five years. This paper presents details of the earthquake’s effects, the early response and the status of the post-earthquake reconstruction progress five years after the earthquake. Official reports from Nepalese government institutions, national and international authorities, government databases and research papers on the Gorkha earthquake were reviewed. The numbers of various infrastructures reconstructed and under construction each year after the earthquake and the reconstruction processes adopted are presented. The results show that 67% of private houses, 74% of educational institutions and 58% of health facilities were reconstructed in the five years.
Vincent, Lauren; Eaton, Brett; Leenman, Anya; Jakob, Matthias
Secondary Geomorphic Processes and their Influence on Alluvial Fan Morphology, Channel Behaviour and Flood Hazards Journal Article
In: Journal of Geophysical Research: Earth Surface, vol. 127, no. 2, 2022.
@article{article1,
title = {Secondary Geomorphic Processes and their Influence on Alluvial Fan Morphology, Channel Behaviour and Flood Hazards },
author = {Lauren Vincent and Brett Eaton and Anya Leenman and Matthias Jakob},
doi = {10.1029/2021JF006371},
year = {2022},
date = {2022-03-31},
urldate = {2022-03-30},
journal = {Journal of Geophysical Research: Earth Surface},
volume = {127},
number = {2},
abstract = {Alluvial fans form through primary and secondary geomorphic processes. Primary processes comprise major geomorphic events that build the fan by transporting sediment from the watershed to the fan; these events occur at decadal time scales. Secondary processes include the smaller flood events which recruit little sediment from the watershed but can re-mobilize and rework sediment already delivered to the fan. The experiments described herein study the effects of secondary processes on alluvial fan morphology and channel behaviour. We conducted four experiments, in which alluvial fans were built by alternating between primary events, with high flows and high sediment supply, and secondary events, with moderate flows and no sediment supply. In our experiments, primary events are best described as debris floods and secondary events correspond to smaller floods with much lower sediment concentrations. The duration of the secondary events varied between experiments, but the number and duration of the primary events was held constant keeping the total volume of sediment delivered to the fan the same. We monitored fan gradient, area, channel patterns and avulsions. Experiments with longer secondary events generated larger fans with gentler gradients. In addition, longer secondary events led to increased flow channelization and centralization between primary events. These morphologic changes resulted in fewer avulsions during primary events, which occurred later during the event. These results indicate that changes to the relative duration of primary and secondary events caused by climate change can affect fan morphology, wet fraction, and avulsion frequency, with implications for potential flood hazard.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Alluvial fans form through primary and secondary geomorphic processes. Primary processes comprise major geomorphic events that build the fan by transporting sediment from the watershed to the fan; these events occur at decadal time scales. Secondary processes include the smaller flood events which recruit little sediment from the watershed but can re-mobilize and rework sediment already delivered to the fan. The experiments described herein study the effects of secondary processes on alluvial fan morphology and channel behaviour. We conducted four experiments, in which alluvial fans were built by alternating between primary events, with high flows and high sediment supply, and secondary events, with moderate flows and no sediment supply. In our experiments, primary events are best described as debris floods and secondary events correspond to smaller floods with much lower sediment concentrations. The duration of the secondary events varied between experiments, but the number and duration of the primary events was held constant keeping the total volume of sediment delivered to the fan the same. We monitored fan gradient, area, channel patterns and avulsions. Experiments with longer secondary events generated larger fans with gentler gradients. In addition, longer secondary events led to increased flow channelization and centralization between primary events. These morphologic changes resulted in fewer avulsions during primary events, which occurred later during the event. These results indicate that changes to the relative duration of primary and secondary events caused by climate change can affect fan morphology, wet fraction, and avulsion frequency, with implications for potential flood hazard.
Gygax, Adrian; Kostaschuk, Rod; Gaib, Sarah
Structural Aspects of the Stabilization of Ten Mile Slide Conference
DFI47 - Leading with Purpose, 2022.
@conference{Conference1,
title = {Structural Aspects of the Stabilization of Ten Mile Slide },
author = {Adrian Gygax and Rod Kostaschuk and Sarah Gaib},
year = {2022},
date = {2022-03-28},
urldate = {2022-03-31},
booktitle = {DFI47 - Leading with Purpose},
abstract = {The British Columbia Ministry of Transportation and Infrastructure (Ministry) recently completed a slope stabilization project at the Ten Mile Slide on Highway 99. The highway is an essential part of the road network connecting the British Columbia (BC) coast with the interior of the province. The slide was first identified in the mid-1980s and has retrogressed more than 250 m upslope since then, leading to continual and expensive repairs to the highway. The Ministry engaged BGC Engineering Ltd. (BGC) and their structural sub-consultant Gygax Engineering Associates Ltd. (GEA) to develop a stabilization scheme that would halt the slide with an acceptable level of residual risk. The design required careful consideration of construction stages and the stresses induced in the structural components as the slide movement was progressively stopped as construction advanced. Four stabilization design options were shortlisted with the preferred option selected in Fall 2016. The selected solution comprised the construction of five rows of post-tensioned soil anchors upslope of the highway and a tied-back concrete tangent pile retaining wall for the roadway itself as well as reconstruction of the highway alignment, grade and drainage through the slide. Works were installed by top-down construction within defined time allowances stipulated in the contract. Significant engineering was undertaken beyond standard design processes for this complex project, such as comprehensive geotechnical investigations, aerial and terrestrial laser scanning and change detection analyses, pre-production test anchors, detailed geo-structural numerical modelling and due diligence activities to validate and optimize the design. The stabilization works have been very successful with the slide response being as predicted and the highway operating again as full two-lane service.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
The British Columbia Ministry of Transportation and Infrastructure (Ministry) recently completed a slope stabilization project at the Ten Mile Slide on Highway 99. The highway is an essential part of the road network connecting the British Columbia (BC) coast with the interior of the province. The slide was first identified in the mid-1980s and has retrogressed more than 250 m upslope since then, leading to continual and expensive repairs to the highway. The Ministry engaged BGC Engineering Ltd. (BGC) and their structural sub-consultant Gygax Engineering Associates Ltd. (GEA) to develop a stabilization scheme that would halt the slide with an acceptable level of residual risk. The design required careful consideration of construction stages and the stresses induced in the structural components as the slide movement was progressively stopped as construction advanced. Four stabilization design options were shortlisted with the preferred option selected in Fall 2016. The selected solution comprised the construction of five rows of post-tensioned soil anchors upslope of the highway and a tied-back concrete tangent pile retaining wall for the roadway itself as well as reconstruction of the highway alignment, grade and drainage through the slide. Works were installed by top-down construction within defined time allowances stipulated in the contract. Significant engineering was undertaken beyond standard design processes for this complex project, such as comprehensive geotechnical investigations, aerial and terrestrial laser scanning and change detection analyses, pre-production test anchors, detailed geo-structural numerical modelling and due diligence activities to validate and optimize the design. The stabilization works have been very successful with the slide response being as predicted and the highway operating again as full two-lane service.
Geertsema, Marten; Menounos, Brian; Bullard, Gemma; Carrivick, Jonathan; Clague, John; Dai, C; Donati, Davide; Ekstrom, Goran; Jackson, Jennifer; Lynett, Patrick; Pichierri, Manuele; Pon, Andy; Shugar, Dan; Stead, Doug; Belluz, Justin Del Bel; Friele, Pierre; Giesbrecht, Ian; Heathfield, Derek; Millard, Thomas; Nasonova, S; Schaeffer, Andrew; Ward, Brent; Blaney, Darren; Blaney, Erik; Brillon, Camille; Bunn, C; Floyd, William; Higman, Bretwood; Hughes, K; Mukherjee, Kriti; Sharp, Meghan
In: Geophysical Research Letters, vol. 49, no. 6, 2022.
@article{journal1,
title = {The 28 November 2020 Landslide, Tsunami, and Outburst Flood – A Hazard Cascade Associated With Rapid Deglaciation at Elliot Creek, British Columbia, Canada},
author = {Marten Geertsema and Brian Menounos and Gemma Bullard and Jonathan Carrivick and John Clague and C Dai and Davide Donati and Goran Ekstrom and Jennifer Jackson and Patrick Lynett and Manuele Pichierri and Andy Pon and Dan Shugar and Doug Stead and Justin Del Bel Belluz and Pierre Friele and Ian Giesbrecht and Derek Heathfield and Thomas Millard and S Nasonova and Andrew Schaeffer and Brent Ward and Darren Blaney and Erik Blaney and Camille Brillon and C Bunn and William Floyd and Bretwood Higman and K Hughes and Kriti Mukherjee and Meghan Sharp},
doi = {10.1029/2021GL096716},
year = {2022},
date = {2022-03-26},
urldate = {2022-03-30},
journal = {Geophysical Research Letters},
volume = {49},
number = {6},
abstract = {We describe and model the evolution of a recent landslide, tsunami, outburst flood, and sediment plume in the southern Coast Mountains, British Columbia, Canada. On November 28, 2020, about 18 million m3 of rock descended 1,000 m from a steep valley wall and traveled across the toe of a glacier before entering a 0.6 km2 glacier lake and producing >100-m high run-up. Water overtopped the lake outlet and scoured a 10-km long channel before depositing debris on a 2-km2 fan below the lake outlet. Floodwater, organic debris, and fine sediment entered a fjord where it produced a 60+km long sediment plume and altered turbidity, water temperature, and water chemistry for weeks. The outburst flood destroyed forest and salmon spawning habitat. Physically based models of the landslide, tsunami, and flood provide real-time simulations of the event and can improve understanding of similar hazard cascades and the risk they pose.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We describe and model the evolution of a recent landslide, tsunami, outburst flood, and sediment plume in the southern Coast Mountains, British Columbia, Canada. On November 28, 2020, about 18 million m3 of rock descended 1,000 m from a steep valley wall and traveled across the toe of a glacier before entering a 0.6 km2 glacier lake and producing >100-m high run-up. Water overtopped the lake outlet and scoured a 10-km long channel before depositing debris on a 2-km2 fan below the lake outlet. Floodwater, organic debris, and fine sediment entered a fjord where it produced a 60+km long sediment plume and altered turbidity, water temperature, and water chemistry for weeks. The outburst flood destroyed forest and salmon spawning habitat. Physically based models of the landslide, tsunami, and flood provide real-time simulations of the event and can improve understanding of similar hazard cascades and the risk they pose.
Figueiredo, Paula; Hill, Jesse; Meschat, Arthur; Scheip, Corey; Stewart, Kevin; Owen, Lewis; Wooten, Richard; Carter, Mark; Szymanski, Eric; Horton, Stephen; Wegmann, Karl; Bohenstiehl, DelWayne; Thompson, Gary; Witt, Anne; Cattanach, Bart
The Mw 5.1, 9 August 2020, Sparta Earthquake, North Carolina: The First Documented Seismic Surface Rupture in the Eastern United States Journal Article
In: GSA Today, vol. 32, no. 3-4, pp. 4-11, 2022.
@article{article1,
title = {The Mw 5.1, 9 August 2020, Sparta Earthquake, North Carolina: The First Documented Seismic Surface Rupture in the Eastern United States},
author = {Paula Figueiredo and Jesse Hill and Arthur Meschat and Corey Scheip and Kevin Stewart and Lewis Owen and Richard Wooten and Mark Carter and Eric Szymanski and Stephen Horton and Karl Wegmann and DelWayne Bohenstiehl and Gary Thompson and Anne Witt and Bart Cattanach},
doi = {10.1130/GSATG517A.1},
year = {2022},
date = {2022-03-25},
urldate = {2022-03-28},
journal = {GSA Today},
volume = {32},
number = {3-4},
pages = {4-11},
abstract = {At 8:07 a.m. EDT on 9 Aug. 2020 a Mw 5.1 earthquake located ~3 km south of Sparta, North Carolina, USA, shook much of the eastern United States, producing the first documented surface rupture due to faulting east of the New Madrid seismic zone. The co-seismic surface rupture was identified along a 2-km-long traceable zone of predominantly reverse displacement, with folding and flexure generating a scarp averaging 8–10-cm-high with a maximum observed height of ~25 cm. Widespread deformation south of the main surface rupture includes cm-dm–long and mm-cm–wide fissures. Two trenches excavated across the surface rupture reveal that this earthquake propagated to the surface along a preexisting structure in the shallow bedrock, which had not been previously identified as an active fault.
Surface ruptures by faulting are rarely reported for M <6 earthquakes, and hence the Sparta earthquake provides an opportunity to improve seismic hazard knowledge associated with these moderate events. Furthermore, this earthquake occurred in a very low strain rate intraplate setting, where earthquake surface deformation, regardless of magnitude, is sparse in time and rare to observe and characterize.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
At 8:07 a.m. EDT on 9 Aug. 2020 a Mw 5.1 earthquake located ~3 km south of Sparta, North Carolina, USA, shook much of the eastern United States, producing the first documented surface rupture due to faulting east of the New Madrid seismic zone. The co-seismic surface rupture was identified along a 2-km-long traceable zone of predominantly reverse displacement, with folding and flexure generating a scarp averaging 8–10-cm-high with a maximum observed height of ~25 cm. Widespread deformation south of the main surface rupture includes cm-dm–long and mm-cm–wide fissures. Two trenches excavated across the surface rupture reveal that this earthquake propagated to the surface along a preexisting structure in the shallow bedrock, which had not been previously identified as an active fault.
Surface ruptures by faulting are rarely reported for M <6 earthquakes, and hence the Sparta earthquake provides an opportunity to improve seismic hazard knowledge associated with these moderate events. Furthermore, this earthquake occurred in a very low strain rate intraplate setting, where earthquake surface deformation, regardless of magnitude, is sparse in time and rare to observe and characterize.
Surface ruptures by faulting are rarely reported for M <6 earthquakes, and hence the Sparta earthquake provides an opportunity to improve seismic hazard knowledge associated with these moderate events. Furthermore, this earthquake occurred in a very low strain rate intraplate setting, where earthquake surface deformation, regardless of magnitude, is sparse in time and rare to observe and characterize.
Hilbich, Christin; Hauck, Christian; Mollaret, Coline; Wainstein, Pablo; Arenson, Lukas
In: The Cryosphere, vol. 16, no. 5, pp. 1845-1872, 2022.
@article{article1_54,
title = {Towards Accurate Quantification of Ice Content in Permafrost of the Central Andes – Part 1: Geophysics-based Estimates from Three Different Regions},
author = {Christin Hilbich and Christian Hauck and Coline Mollaret and Pablo Wainstein and Lukas Arenson},
doi = {10.5194/tc-16-1845-2022},
year = {2022},
date = {2022-02-15},
journal = {The Cryosphere},
volume = {16},
number = {5},
pages = {1845-1872},
abstract = {Increasing water scarcity in the Central Andes due to ongoing climate change recently caused a controversy and debate on the significance of permafrost occurrences for the hydrologic cycle. The lack of comprehensive field measurements and quantitative data on the local variability in internal structure and ground ice content further exacerbates the situation. We present field-based data from six extensive geophysical campaigns undertaken since 2016 in three different high-altitude regions of the Central Andes of Chile and Argentina (28 to 32∘ S). Our data cover various permafrost landforms ranging from ice-poor bedrock to ice-rich rock glaciers and are complemented by ground truthing information from boreholes and numerous test pits near the geophysical profiles. In addition to determining the thickness of the potential ice-rich layers from the individual profiles, we also use a quantitative four-phase model to estimate the volumetric ground ice content in representative zones of the geophysical profiles. Our analysis of 52 geoelectrical and 24 refraction seismic profiles within this study confirmed that ice-rich permafrost is not restricted to rock glaciers but is also observed in non-rock-glacier permafrost slopes in the form of interstitial ice, as well as layers with excess ice, resulting in substantial ice contents. Consequently, non-rock-glacier permafrost landforms, whose role for local hydrology has so far not been considered in remote-sensing-based approaches, may be similarly relevant in terms of ground ice content on a catchment scale and should not be ignored when quantifying the potential hydrological significance of permafrost. We show that field-geophysics-based estimates of ground ice content, while more labour intensive, are considerably more accurate than remote sensing approaches. The geophysical data can then be further used in upscaling studies to the catchment scale in order to reliably estimate the hydrological significance of permafrost within a catchment.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Increasing water scarcity in the Central Andes due to ongoing climate change recently caused a controversy and debate on the significance of permafrost occurrences for the hydrologic cycle. The lack of comprehensive field measurements and quantitative data on the local variability in internal structure and ground ice content further exacerbates the situation. We present field-based data from six extensive geophysical campaigns undertaken since 2016 in three different high-altitude regions of the Central Andes of Chile and Argentina (28 to 32∘ S). Our data cover various permafrost landforms ranging from ice-poor bedrock to ice-rich rock glaciers and are complemented by ground truthing information from boreholes and numerous test pits near the geophysical profiles. In addition to determining the thickness of the potential ice-rich layers from the individual profiles, we also use a quantitative four-phase model to estimate the volumetric ground ice content in representative zones of the geophysical profiles. Our analysis of 52 geoelectrical and 24 refraction seismic profiles within this study confirmed that ice-rich permafrost is not restricted to rock glaciers but is also observed in non-rock-glacier permafrost slopes in the form of interstitial ice, as well as layers with excess ice, resulting in substantial ice contents. Consequently, non-rock-glacier permafrost landforms, whose role for local hydrology has so far not been considered in remote-sensing-based approaches, may be similarly relevant in terms of ground ice content on a catchment scale and should not be ignored when quantifying the potential hydrological significance of permafrost. We show that field-geophysics-based estimates of ground ice content, while more labour intensive, are considerably more accurate than remote sensing approaches. The geophysical data can then be further used in upscaling studies to the catchment scale in order to reliably estimate the hydrological significance of permafrost within a catchment.
van Veen, Megan; Porter, Mike; Lato, Matthew; Mitchell, Andrew; Fish, Colleen; van Gassen, Wim
Using Tree Stems in Multi-Temporal Terrestrial Lidar Scanning Data to Monitor Landslides on Vegetated Slopes Journal Article
In: Landslides, vol. 19, no. 4, pp. 829-840, 2022.
@article{article1,
title = {Using Tree Stems in Multi-Temporal Terrestrial Lidar Scanning Data to Monitor Landslides on Vegetated Slopes},
author = {Megan van Veen and Mike Porter and Matthew Lato and Andrew Mitchell and Colleen Fish and Wim van Gassen},
doi = {10.1007/s10346-021-01815-1},
year = {2022},
date = {2022-02-14},
urldate = {2022-02-14},
journal = {Landslides},
volume = {19},
number = {4},
pages = {829-840},
abstract = {Terrestrial lidar scanning (TLS) has become a widely accepted expert tool for monitoring geohazards on bare or sparsely vegetated slopes through change detection. While trees can be an important indicator of landslide activity at a slope, vegetation is often removed or ignored when monitoring landslides with TLS. This paper explores the use of multi-temporal terrestrial lidar scanning at a slope in the Peace River valley of British Columbia to test the author’s hypothesis that tree stems in TLS data can be used to track landslide displacement and provide insight into the landslide mechanism. Six TLS datasets, each collected approximately 6 months apart, are used, and roto-translation methods are employed to determine the azimuth, plunge, and toppling angle of trees between each TLS scan. The tree displacement patterns are compared to TLS change detection results on bare-ground, and to single-point tracking techniques for extracting displacement vectors. Considerations for future applications are discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Terrestrial lidar scanning (TLS) has become a widely accepted expert tool for monitoring geohazards on bare or sparsely vegetated slopes through change detection. While trees can be an important indicator of landslide activity at a slope, vegetation is often removed or ignored when monitoring landslides with TLS. This paper explores the use of multi-temporal terrestrial lidar scanning at a slope in the Peace River valley of British Columbia to test the author’s hypothesis that tree stems in TLS data can be used to track landslide displacement and provide insight into the landslide mechanism. Six TLS datasets, each collected approximately 6 months apart, are used, and roto-translation methods are employed to determine the azimuth, plunge, and toppling angle of trees between each TLS scan. The tree displacement patterns are compared to TLS change detection results on bare-ground, and to single-point tracking techniques for extracting displacement vectors. Considerations for future applications are discussed.
Mitchell, Andrew; Zubrycky, Sophia; McDougall, Scott; Aaron, Jordan; Jacquemart, Mylene; Hubl, Johannes; Roland, Kaitna; Graf, Christoph
Variable Hydrograph Inputs for a Numerical Debris-Flow Runout Model Journal Article
In: Natural Hazards and Earth System Sciences, vol. 22, no. 5, pp. 1627-1654, 2022.
@article{article1,
title = {Variable Hydrograph Inputs for a Numerical Debris-Flow Runout Model},
author = {Andrew Mitchell and Sophia Zubrycky and Scott McDougall and Jordan Aaron and Mylene Jacquemart and Johannes Hubl and Kaitna Roland and Christoph Graf},
doi = {10.5194/nhess-22-1627-2022},
year = {2022},
date = {2022-02-08},
urldate = {2022-02-28},
journal = {Natural Hazards and Earth System Sciences},
volume = {22},
number = {5},
pages = {1627-1654},
abstract = {Debris flows affect people and infrastructure around the world, and as a result, many numerical models and modelling approaches have been developed to simulate their impacts. Observations from instrumented debris-flow channels show that variability in inflow depth, velocity, and discharge in real debris flows is much higher than what is typically used in numerical simulations. However, the effect of this natural variability on numerical model outputs is not well known. In this study, we examine the effects of using complex inflow time series within a single-phase runout model utilizing a Voellmy flow-resistance model. The interactions between model topography and flow resistance were studied first using a simple triangular hydrograph, which showed that simulated discharges change because of local slopes and Voellmy parameters. Next, more complex inflows were tested using time series based on 24 real debris-flow hydrographs initiated from three locations. We described a simple method to scale inflow hydrographs by defining a target event volume and maximum allowable peak discharge. The results showed a large variation in simulated flow depths and velocities arising from the variable inflow. The effects of variable-inflow conditions were demonstrated in simulations of two case histories of real debris flows, where the variation in inflow leads to significant variations in the simulation outputs. The real debris-flow hydrographs were used to provide an indication of the range of impacts that may result from the natural variability in inflow conditions. These results demonstrate that variation in inflow conditions can lead to reasonable estimates of the potential variation in impacts.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Debris flows affect people and infrastructure around the world, and as a result, many numerical models and modelling approaches have been developed to simulate their impacts. Observations from instrumented debris-flow channels show that variability in inflow depth, velocity, and discharge in real debris flows is much higher than what is typically used in numerical simulations. However, the effect of this natural variability on numerical model outputs is not well known. In this study, we examine the effects of using complex inflow time series within a single-phase runout model utilizing a Voellmy flow-resistance model. The interactions between model topography and flow resistance were studied first using a simple triangular hydrograph, which showed that simulated discharges change because of local slopes and Voellmy parameters. Next, more complex inflows were tested using time series based on 24 real debris-flow hydrographs initiated from three locations. We described a simple method to scale inflow hydrographs by defining a target event volume and maximum allowable peak discharge. The results showed a large variation in simulated flow depths and velocities arising from the variable inflow. The effects of variable-inflow conditions were demonstrated in simulations of two case histories of real debris flows, where the variation in inflow leads to significant variations in the simulation outputs. The real debris-flow hydrographs were used to provide an indication of the range of impacts that may result from the natural variability in inflow conditions. These results demonstrate that variation in inflow conditions can lead to reasonable estimates of the potential variation in impacts.
Arenson, Lukas; Brooks, Heather
When Permafrost Begins Warming Up Journal Article
In: GEOSTRATA, vol. 26, no. 3, pp. 58-64, 2022.
@article{article1,
title = {When Permafrost Begins Warming Up},
author = {Lukas Arenson and Heather Brooks},
year = {2022},
date = {2022-02-02},
urldate = {2022-02-02},
journal = {GEOSTRATA},
volume = {26},
number = {3},
pages = {58-64},
abstract = {As warming in the Arctic advances at unprecedented rates, geotechnical engineers are faced with unique challenges when designing infrastructure foundations. Traditional approaches may have to be reconsidered.
},
keywords = {},
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As warming in the Arctic advances at unprecedented rates, geotechnical engineers are faced with unique challenges when designing infrastructure foundations. Traditional approaches may have to be reconsidered.
2021
Rousseau, Prasanna; Sivathayalan, Siva
A Hollow Cylinder Torsional Shear Device to Explore Behavior of Soils Subjected to Complex Rotation of Principal Stresses Journal Article
In: Geotechnical Testing Journal, vol. 44, no. 6, 2021.
@article{articleb,
title = {A Hollow Cylinder Torsional Shear Device to Explore Behavior of Soils Subjected to Complex Rotation of Principal Stresses},
author = {Prasanna Rousseau and Siva Sivathayalan},
doi = {10.1520/GTJ20190394},
year = {2021},
date = {2021-12-31},
urldate = {2021-12-31},
journal = {Geotechnical Testing Journal},
volume = {44},
number = {6},
abstract = {A hollow cylinder torsional shear device that is modified to simulate more generalized earthquake loading, involving simultaneous compression and shear wave loading in situ, is presented. The nature and degree of stress rotation due to coupled action of compression waves and shear waves are discussed, and illustrative experiments conducted to simulate different loading scenarios in the laboratory are presented. The stress rotation due to this coupled loading is significantly influenced by the initial consolidation stress state and shearing parameters such as the ratio between shear stress and normal stress increments (ΔS/ΔN) and the phase shift (ϕ) between the waves. The representative (ΔS/ΔN) ratios were obtained from the numerical simulations and used in hollow cylinder torsional shear apparatus to investigate the cyclic response of Fraser River sand under the simultaneous action of normal and shear stresses. Typical cyclic test results demonstrating the capability of a hollow cylinder torsional shear apparatus commissioned at Carleton University in following complicated cyclic loading paths are presented in this paper. It is noted that loading under such nonconventional stress paths, such as elliptical and circular paths, could be initiated along different pathways. Cyclic test results along these pathways demonstrate that soil response is dependent on the overall path including the initial stress state. Test results also highlighted the significance of stress rotation and cyclic stress paths in affecting the liquefaction susceptibility of sands.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A hollow cylinder torsional shear device that is modified to simulate more generalized earthquake loading, involving simultaneous compression and shear wave loading in situ, is presented. The nature and degree of stress rotation due to coupled action of compression waves and shear waves are discussed, and illustrative experiments conducted to simulate different loading scenarios in the laboratory are presented. The stress rotation due to this coupled loading is significantly influenced by the initial consolidation stress state and shearing parameters such as the ratio between shear stress and normal stress increments (ΔS/ΔN) and the phase shift (ϕ) between the waves. The representative (ΔS/ΔN) ratios were obtained from the numerical simulations and used in hollow cylinder torsional shear apparatus to investigate the cyclic response of Fraser River sand under the simultaneous action of normal and shear stresses. Typical cyclic test results demonstrating the capability of a hollow cylinder torsional shear apparatus commissioned at Carleton University in following complicated cyclic loading paths are presented in this paper. It is noted that loading under such nonconventional stress paths, such as elliptical and circular paths, could be initiated along different pathways. Cyclic test results along these pathways demonstrate that soil response is dependent on the overall path including the initial stress state. Test results also highlighted the significance of stress rotation and cyclic stress paths in affecting the liquefaction susceptibility of sands.
Rafi, Jalaleddin; Stille, Håkan
A Method for Determining Grouting Pressure and Stop Criteria to Control Grout Spread Distance and Fracture Dilation Journal Article
In: Tunnelling and Underground Space Technology, vol. 112, 2021.
@article{article1,
title = {A Method for Determining Grouting Pressure and Stop Criteria to Control Grout Spread Distance and Fracture Dilation},
author = {Jalaleddin Rafi and Håkan Stille},
doi = {10.1016/j.tust.2021.103885},
year = {2021},
date = {2021-12-29},
urldate = {2021-06-01},
journal = {Tunnelling and Underground Space Technology},
volume = {112},
abstract = {Determining optimum pressure in a grouting procedure affects a project's outcome as well as associated costs. Application of relatively low pressure may lead to insufficient grout spread around the borehole and prolongation of grouting time. On the other hand, a pressure higher than in-situ stresses can lead to jacking of the fractures and consequently increase of usage of grout, and in much higher pressures, ground heaving and uplifts. In a review of current practices, the ‘apparent lugeon’ method uses low pressure regardless of geology and function of the grouted zone. The theoretical approach of RTGC estimates the grout spread from grouting borehole in a fracture with constant size aperture, which obligates the usage of a pressure that avoids any deformations. On the other hand, the GIN method appreciates the usage of higher grouting pressures while the induced energy is controlled. However, the controlling Grout Intensity Number is determined based on experience and provides no information regarding the distance that grout mix is spreading and the state of fracture during grouting. The present study discusses an analytical approach that defines stop criteria that allow the spread of grout to a certain distance while controlling deformations to the extent that ensures fracture jacking remains beneficial. To elaborate this approach, first the concept of fracture jacking and approaches for detecting onset and duration of it are reviewed. This is followed by a discussion of the positive and negative effects of fracture jacking and the determination of thresholds for limiting these deformations. The paper goes on to explain the analytical solution for establishing the Deformation Limiting Curves as a stop criterion and estimation of the grout spread distance in a continuously dilating fracture. The significance and benefits of this solution are argued through case studies involving different functions and geological conditions. It is concluded that understanding the function of the grouted zone and geological conditions to define the grouting requirements, recognizing the risks associated with under or over spreading of grout and jacking of rock fractures, and using proper stop criteria to control these risks, would allow the use of an optimum grouting pressure.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Determining optimum pressure in a grouting procedure affects a project's outcome as well as associated costs. Application of relatively low pressure may lead to insufficient grout spread around the borehole and prolongation of grouting time. On the other hand, a pressure higher than in-situ stresses can lead to jacking of the fractures and consequently increase of usage of grout, and in much higher pressures, ground heaving and uplifts. In a review of current practices, the ‘apparent lugeon’ method uses low pressure regardless of geology and function of the grouted zone. The theoretical approach of RTGC estimates the grout spread from grouting borehole in a fracture with constant size aperture, which obligates the usage of a pressure that avoids any deformations. On the other hand, the GIN method appreciates the usage of higher grouting pressures while the induced energy is controlled. However, the controlling Grout Intensity Number is determined based on experience and provides no information regarding the distance that grout mix is spreading and the state of fracture during grouting. The present study discusses an analytical approach that defines stop criteria that allow the spread of grout to a certain distance while controlling deformations to the extent that ensures fracture jacking remains beneficial. To elaborate this approach, first the concept of fracture jacking and approaches for detecting onset and duration of it are reviewed. This is followed by a discussion of the positive and negative effects of fracture jacking and the determination of thresholds for limiting these deformations. The paper goes on to explain the analytical solution for establishing the Deformation Limiting Curves as a stop criterion and estimation of the grout spread distance in a continuously dilating fracture. The significance and benefits of this solution are argued through case studies involving different functions and geological conditions. It is concluded that understanding the function of the grouted zone and geological conditions to define the grouting requirements, recognizing the risks associated with under or over spreading of grout and jacking of rock fractures, and using proper stop criteria to control these risks, would allow the use of an optimum grouting pressure.
Weidner, Luke; van Veen, Megan; Lato, Matthew; Walton, Gabriel
An Algorithm for Measuring Landslide Deformation in Terrestrial Lidar Point Clouds Using Trees Journal Article
In: Landslides, vol. 18, no. 11, pp. 3547-3558, 2021.
@article{article1,
title = {An Algorithm for Measuring Landslide Deformation in Terrestrial Lidar Point Clouds Using Trees},
author = {Luke Weidner and Megan van Veen and Matthew Lato and Gabriel Walton},
doi = {10.1007/s10346-021-01723-4},
year = {2021},
date = {2021-12-23},
urldate = {2021-12-20},
journal = {Landslides},
volume = {18},
number = {11},
pages = {3547-3558},
abstract = {Terrestrial lidar data is a powerful resource for moni-toring geohazards such as rockfall and landslides. However, veg-etated landslides with horizontal shear surfaces remain difficult to characterize accurately due to a lack of exposed and appropriately oriented surfaces with respect to the lidar scanner. As an alterna-tive, the movements of objects on the slope, such as trees, can be used to estimate slope movement. This paper demonstrates a novel semi-automated algorithm to extract and calculate the 3D displace-ment of trees on a slow-moving landslide, enabling more detailed landslide deformation analysis using point clouds. The method first uses local geometric descriptors to identify raw points correspond-ing to tree trunks. Several machine learning techniques are com-pared for this step, and an unsupervised decision tree algorithm with an accuracy of 84% is selected as the final method. After clus-tering points into individual trunks, trunks are matched through time according to several matching criteria, and their movement and rotation are then calculated using an iterative closest point algorithm. Accuracy of the automated displacement calculations is confirmed through comparison with manual point cloud measure-ments. A case study is presented demonstrating the method on a landslide through different seasonal vegetation changes, illustrat-ing that algorithm parameters can be quickly adjusted to account for variations in tree species, density of foliage, scanner distance, and other factors. The final matching precision is demonstrated to be between 89 and 99%, indicating a very small number of false-positive matches.},
keywords = {},
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Terrestrial lidar data is a powerful resource for moni-toring geohazards such as rockfall and landslides. However, veg-etated landslides with horizontal shear surfaces remain difficult to characterize accurately due to a lack of exposed and appropriately oriented surfaces with respect to the lidar scanner. As an alterna-tive, the movements of objects on the slope, such as trees, can be used to estimate slope movement. This paper demonstrates a novel semi-automated algorithm to extract and calculate the 3D displace-ment of trees on a slow-moving landslide, enabling more detailed landslide deformation analysis using point clouds. The method first uses local geometric descriptors to identify raw points correspond-ing to tree trunks. Several machine learning techniques are com-pared for this step, and an unsupervised decision tree algorithm with an accuracy of 84% is selected as the final method. After clus-tering points into individual trunks, trunks are matched through time according to several matching criteria, and their movement and rotation are then calculated using an iterative closest point algorithm. Accuracy of the automated displacement calculations is confirmed through comparison with manual point cloud measure-ments. A case study is presented demonstrating the method on a landslide through different seasonal vegetation changes, illustrat-ing that algorithm parameters can be quickly adjusted to account for variations in tree species, density of foliage, scanner distance, and other factors. The final matching precision is demonstrated to be between 89 and 99%, indicating a very small number of false-positive matches.
van Veen, Megan; Froese, Corey; Lato, Matthew; Hunter, Gord; Tom, Kneale
An Integrated Remote Sensing Assessment of the Drynoch Earth Flow Conference
GeoNiagra 2021: Creating a sustainable and smart future, 2021.
@conference{Conference1,
title = {An Integrated Remote Sensing Assessment of the Drynoch Earth Flow},
author = {Megan van Veen and Corey Froese and Matthew Lato and Gord Hunter and Kneale Tom},
year = {2021},
date = {2021-12-22},
urldate = {2021-12-24},
booktitle = {GeoNiagra 2021: Creating a sustainable and smart future},
abstract = {Satellite based InSAR and airborne lidar scanning (ALS) were utilized to characterize movements of the Drynoch Earth Flow in southern British Columbia. Change detection undertaken using three epochs of airborne lidar data was able to quantify displacements on the most active zones of the earth flow, with total annual displacements up to 4.6 m, while the InSAR data were used to quantify more slow-moving zones on the fringes of the earth flow that were not detectable with the lidar change detection. The combination of the two technologies allowed for better definition of the spatial extents and rates of deformation that can be integrated into future planning of risk management activities in relation to the highway and railway that are located near the toe of the earth flow.},
keywords = {},
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Satellite based InSAR and airborne lidar scanning (ALS) were utilized to characterize movements of the Drynoch Earth Flow in southern British Columbia. Change detection undertaken using three epochs of airborne lidar data was able to quantify displacements on the most active zones of the earth flow, with total annual displacements up to 4.6 m, while the InSAR data were used to quantify more slow-moving zones on the fringes of the earth flow that were not detectable with the lidar change detection. The combination of the two technologies allowed for better definition of the spatial extents and rates of deformation that can be integrated into future planning of risk management activities in relation to the highway and railway that are located near the toe of the earth flow.
Lato, Matthew; Harrap, Robin; MacCormack, Kelsey
Anticipated Technological Advances Book Chapter
In: Applied Multidimensional Geological Modeling: Informing sustainable human interactions with the shallow subsurface, pp. 619-633, 2021.
@inbook{Bookchp1,
title = {Anticipated Technological Advances},
author = {Matthew Lato and Robin Harrap and Kelsey MacCormack},
doi = {10.1002/9781119163091.ch26},
year = {2021},
date = {2021-12-21},
urldate = {2021-06-15},
booktitle = {Applied Multidimensional Geological Modeling: Informing sustainable human interactions with the shallow subsurface},
pages = {619-633},
abstract = {Geological modeling and visualization occupy a relatively small market segment within the overall field of computing hardware and software. Geological modeling requirements are typically satisfied by adapting tools and techniques developed for other market segments. This chapter briefly explores several areas where emerging technological advancements are influencing geological modeling and geological model visualization. The technological trends are believed to be key influences that are likely to affect geological modeling and visualization in the near to mid-term future. The chapter also provides examples of where the advances are happening, why they are happening, and their likely outcomes. Societal decisions concerning funding and intellectual property rights are perhaps the most critical controls on the future of geological modeling and visualization. Future developments will see better integration between data within and external to the geosciences.},
keywords = {},
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Geological modeling and visualization occupy a relatively small market segment within the overall field of computing hardware and software. Geological modeling requirements are typically satisfied by adapting tools and techniques developed for other market segments. This chapter briefly explores several areas where emerging technological advancements are influencing geological modeling and geological model visualization. The technological trends are believed to be key influences that are likely to affect geological modeling and visualization in the near to mid-term future. The chapter also provides examples of where the advances are happening, why they are happening, and their likely outcomes. Societal decisions concerning funding and intellectual property rights are perhaps the most critical controls on the future of geological modeling and visualization. Future developments will see better integration between data within and external to the geosciences.
Forbes, Bradley; Ouellet, Susanne; Suszek, Naia; Lato, Matthew; Russell, Brad
Application of Distributed Acoustic Sensing Within a Tailings Dam Warning System Conference
Tailings and Mine Waste Conference, 2021.
@conference{Conference1,
title = {Application of Distributed Acoustic Sensing Within a Tailings Dam Warning System },
author = {Bradley Forbes and Susanne Ouellet and Naia Suszek and Matthew Lato and Brad Russell},
year = {2021},
date = {2021-12-19},
urldate = {2021-12-27},
booktitle = {Tailings and Mine Waste Conference},
abstract = {Recent tailings dam failures have prompted revisions and enhancements to existing tailings dam monitoring best practices globally. A novel monitoring method is presented to act as a component of an overall tailings dam warning system, capable of providing near real-time detection of a potential dam failure at a North American tailings facility. This method measures vibrations along an optical fiber, using a Distributed Acoustic Sensing system. Several kilometers of a telecommunications-grade fiber optic cable were installed one meter below the crest of mul-tiple tailings dam structures, providing the equivalence of over a thousand discrete measurement points. The sensing system is capable of kilohertz scale, thus providing both high spatial and high temporal resolution assessment along the fiber. This paper details the considerations to install this system at the tailings facility and provides an overview of calibration to detect significant disturb-ances to the cable, while limiting the number of nuisance alarms.},
keywords = {},
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Recent tailings dam failures have prompted revisions and enhancements to existing tailings dam monitoring best practices globally. A novel monitoring method is presented to act as a component of an overall tailings dam warning system, capable of providing near real-time detection of a potential dam failure at a North American tailings facility. This method measures vibrations along an optical fiber, using a Distributed Acoustic Sensing system. Several kilometers of a telecommunications-grade fiber optic cable were installed one meter below the crest of mul-tiple tailings dam structures, providing the equivalence of over a thousand discrete measurement points. The sensing system is capable of kilohertz scale, thus providing both high spatial and high temporal resolution assessment along the fiber. This paper details the considerations to install this system at the tailings facility and provides an overview of calibration to detect significant disturb-ances to the cable, while limiting the number of nuisance alarms.
Noetzli, Jeannette; Arenson, Lukas; Bast, Alexander; Beutel, Jan; Delaloye, Reynald; Farinotti, Daniel; Gruber, Stephan; Gubler, Hansueli; Haeberli, Wilfried; Hasler, Andreas; Hauck, Christian; Hiller, Martin; Hoelzle, Martin; Lambiel, Christophe; Pellet, Cécile; Springman, Sarah; Muehll, Daniel; Phillips, Marcia
Best Practice for Measuring Permafrost Temperature in Boreholes Based on the Experience in the Swiss Alps Journal Article
In: Frontiers in Earth Science, vol. 9, 2021.
@article{article1,
title = {Best Practice for Measuring Permafrost Temperature in Boreholes Based on the Experience in the Swiss Alps},
author = {Jeannette Noetzli and Lukas Arenson and Alexander Bast and Jan Beutel and Reynald Delaloye and Daniel Farinotti and Stephan Gruber and Hansueli Gubler and Wilfried Haeberli and Andreas Hasler and Christian Hauck and Martin Hiller and Martin Hoelzle and Christophe Lambiel and Cécile Pellet and Sarah Springman and Daniel Muehll and Marcia Phillips},
doi = {10.3389/feart.2021.607875},
year = {2021},
date = {2021-12-03},
urldate = {2021-12-30},
journal = {Frontiers in Earth Science},
volume = {9},
abstract = {Temperature measurements in boreholes are the most common method allowing the quantitative and direct observation of permafrost evolution in the context of climate change. Existing boreholes and monitoring networks often emerged in a scientific context targeting different objectives and with different setups. A standardized, well-planned and robust instrumentation of boreholes for long-term operation is crucial to deliver comparable, high-quality data for scientific analyses and assessments. However, only a limited number of guidelines are available, particularly for mountain regions. In this paper, we discuss challenges and devise best practice recommendations for permafrost temperature measurements at single sites as well as in a network, based on two decades of experience gained in the framework of the Swiss Permafrost Monitoring Network PERMOS. These recommendations apply to permafrost observations in mountain regions, although many aspects also apply to polar lowlands. The main recommendations are (1) to thoroughly consider criteria for site selection based on the objective of the measurements as well as on preliminary studies and available data, (2) to define the sampling strategy during planification, (3) to engage experienced drilling teams who can cope with inhomogeneous and potentially unstable subsurface material, (4) to select standardized and robust instrumentation with high accuracy temperature sensors and excellent long-term stability when calibrated at 0°C, ideally with double sensors at key depths for validation and substitution of questionable data, (5) to apply standardized maintenance procedures allowing maximum comparability and minimum data processing, (6) to implement regular data control procedures, and (7) to ensure remote data access allowing for rapid trouble shooting and timely reporting. Data gaps can be avoided by timely planning of replacement boreholes. Recommendations for standardized procedures regarding data quality documentation, processing and final publication will follow later.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Temperature measurements in boreholes are the most common method allowing the quantitative and direct observation of permafrost evolution in the context of climate change. Existing boreholes and monitoring networks often emerged in a scientific context targeting different objectives and with different setups. A standardized, well-planned and robust instrumentation of boreholes for long-term operation is crucial to deliver comparable, high-quality data for scientific analyses and assessments. However, only a limited number of guidelines are available, particularly for mountain regions. In this paper, we discuss challenges and devise best practice recommendations for permafrost temperature measurements at single sites as well as in a network, based on two decades of experience gained in the framework of the Swiss Permafrost Monitoring Network PERMOS. These recommendations apply to permafrost observations in mountain regions, although many aspects also apply to polar lowlands. The main recommendations are (1) to thoroughly consider criteria for site selection based on the objective of the measurements as well as on preliminary studies and available data, (2) to define the sampling strategy during planification, (3) to engage experienced drilling teams who can cope with inhomogeneous and potentially unstable subsurface material, (4) to select standardized and robust instrumentation with high accuracy temperature sensors and excellent long-term stability when calibrated at 0°C, ideally with double sensors at key depths for validation and substitution of questionable data, (5) to apply standardized maintenance procedures allowing maximum comparability and minimum data processing, (6) to implement regular data control procedures, and (7) to ensure remote data access allowing for rapid trouble shooting and timely reporting. Data gaps can be avoided by timely planning of replacement boreholes. Recommendations for standardized procedures regarding data quality documentation, processing and final publication will follow later.
Lato, Matthew
In: Canadian Geotechnical Journal, vol. 58, no. 8, pp. 1065-1076, 2021.
@article{article1,
title = {Canadian Geotechnical Colloquium: Three-Dimensional Remote Sensing, Four-Dimensional Analysis and Visualization in Geotechnical Engineering — State of the Art and Outlook },
author = {Matthew Lato},
doi = {10.1139/cgj-2020-0399},
year = {2021},
date = {2021-11-30},
urldate = {2021-10-06},
journal = {Canadian Geotechnical Journal},
volume = {58},
number = {8},
pages = {1065-1076},
abstract = {Successful geotechnical projects occur when the design is based on a thorough understanding of the geologic and environmental systems and the interaction of these systems over time. The ability to examine and track movement through space and time has been an essential part of the geoprofessional’s toolkit since the onset of the practice. Since the early 2000s, high-resolution three-dimensional (3D) topographic data have begun to transform how we map and understand movement through time across spatially extensive regions at unprecedented levels of accuracy and confidence. This paper examines how high-resolution 3D topographical data, four-dimensional (4D) analysis, and visualization of data in 3D environments can improve our ability to better understand changes in the morphology and material behaviour through time, leading to better decisions and better outcomes. Evolution of advancements made over the past 20 years is presented through case studies where positive impacts were realized through the adoption of 3D remote sensing and 4D analysis, and cases where data could be used in the future to improve outcomes. The paper presents current research being done to further improve processing techniques and exploit new data collection and computational processing capabilities, pushing the capability of time-dependant 4D geotechnical monitoring to new limits.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Successful geotechnical projects occur when the design is based on a thorough understanding of the geologic and environmental systems and the interaction of these systems over time. The ability to examine and track movement through space and time has been an essential part of the geoprofessional’s toolkit since the onset of the practice. Since the early 2000s, high-resolution three-dimensional (3D) topographic data have begun to transform how we map and understand movement through time across spatially extensive regions at unprecedented levels of accuracy and confidence. This paper examines how high-resolution 3D topographical data, four-dimensional (4D) analysis, and visualization of data in 3D environments can improve our ability to better understand changes in the morphology and material behaviour through time, leading to better decisions and better outcomes. Evolution of advancements made over the past 20 years is presented through case studies where positive impacts were realized through the adoption of 3D remote sensing and 4D analysis, and cases where data could be used in the future to improve outcomes. The paper presents current research being done to further improve processing techniques and exploit new data collection and computational processing capabilities, pushing the capability of time-dependant 4D geotechnical monitoring to new limits.
Caruso, Mario; Ferris, Gerald; Heggen, Hans; Delanty, Burke
Challenges Related to Pipeline Free Spans in Watercourse Crossings Conference
International Pipeline Geotechnical Conference, 2021.
@conference{Conference1,
title = {Challenges Related to Pipeline Free Spans in Watercourse Crossings },
author = {Mario Caruso and Gerald Ferris and Hans Heggen and Burke Delanty},
doi = {10.1115/IPG2021-65070},
year = {2021},
date = {2021-11-24},
urldate = {2021-11-24},
booktitle = {International Pipeline Geotechnical Conference},
abstract = {Free span assessment in watercourse crossings for the on-shore pipeline industry has become a more and more important part of pipeline integrity practice. One reason is that it has become increasingly well known that the dominant cause of pipeline failures in watercourse crossings is fatigue failure due to vortex induced vibrations at pipeline free spans. Recognition of this is now being identified in industry recommended practices and owners are incorporating this type of assessment into their pipeline integrity management practice. On shore pipelines are not designed with an allowable free span as is the practice with off-shore pipelines, but are buried. Design codes specify minimum depths of cover when constructed and indicate that pipelines should be maintained so that no excessive loads occur. In the past the no excessive loads requirement has been interpreted that the pipeline must remained buried. As experience from the off-shore environment and increasingly from experience on-shore has shown that most exposed and/or free spans do not fail. Due to various river erosion mechanisms; scour, bank erosion or avulsion, previously buried pipelines do develop free spans. Some of the free spans fail and release products directly into the watercourse. Failures, particularly for liquid products, are very expensive due to the economic loss, repair costs and environment clean-up of the watercourse and its banks. Similarly, costs associated with pipeline replacement for free spanning pipelines or repair of pipelines that might develop free spans are relatively high. It is important to develop an understanding of the probability of the pipeline failing due to a free span, or put another way, determine which free span is a threat to integrity. This paper discusses some of the challenges with assessing free spans in watercourse crossings as part of integrity programs and highlights experiences in assessing this threat to integrity. The objective of this paper is to discuss some of the key uncertainties related to the management of the threat due to free spans. These uncertainties are due to the reliability of information about the free span, water velocity and condition of the pipelines.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Free span assessment in watercourse crossings for the on-shore pipeline industry has become a more and more important part of pipeline integrity practice. One reason is that it has become increasingly well known that the dominant cause of pipeline failures in watercourse crossings is fatigue failure due to vortex induced vibrations at pipeline free spans. Recognition of this is now being identified in industry recommended practices and owners are incorporating this type of assessment into their pipeline integrity management practice. On shore pipelines are not designed with an allowable free span as is the practice with off-shore pipelines, but are buried. Design codes specify minimum depths of cover when constructed and indicate that pipelines should be maintained so that no excessive loads occur. In the past the no excessive loads requirement has been interpreted that the pipeline must remained buried. As experience from the off-shore environment and increasingly from experience on-shore has shown that most exposed and/or free spans do not fail. Due to various river erosion mechanisms; scour, bank erosion or avulsion, previously buried pipelines do develop free spans. Some of the free spans fail and release products directly into the watercourse. Failures, particularly for liquid products, are very expensive due to the economic loss, repair costs and environment clean-up of the watercourse and its banks. Similarly, costs associated with pipeline replacement for free spanning pipelines or repair of pipelines that might develop free spans are relatively high. It is important to develop an understanding of the probability of the pipeline failing due to a free span, or put another way, determine which free span is a threat to integrity. This paper discusses some of the challenges with assessing free spans in watercourse crossings as part of integrity programs and highlights experiences in assessing this threat to integrity. The objective of this paper is to discuss some of the key uncertainties related to the management of the threat due to free spans. These uncertainties are due to the reliability of information about the free span, water velocity and condition of the pipelines.
Pugh, E; Olefeldt, David; Leader, S; Hokanson, Kelly; Devito, Kevin
In: Water Resources Research, vol. 57, no. 11, 2021.
@article{article1,
title = {Characteristics of Dissolved Organic Carbon in Boreal Lakes - High Spatial and Inter-Annual Variability Controlled by Landscape Attributes and Wet-Dry Periods},
author = {E Pugh and David Olefeldt and S Leader and Kelly Hokanson and Kevin Devito},
doi = {10.1029/2021WR030021},
year = {2021},
date = {2021-11-23},
urldate = {2021-11-24},
journal = {Water Resources Research},
volume = {57},
number = {11},
abstract = {Concentration and chemical composition of dissolved organic carbon (DOC) influence several lake functions; greenhouse gas exchange, nutrient cycling, food webs, and water treatability. To assess spatial and inter-annual controls on DOC characteristics, 34 lakes were sampled annually for 8 years on the Boreal Plains, Western Canada—a region with heterogeneous surficial geology, and a sub-humid climate with pronounced inter-annual wet-dry periods. Large spatial variability in long-term average DOC concentration (10–49 mg C L−1) and aromaticity (SUVA254: 1.2–3.9 L mg−1 C m−1) among lakes was found. Higher DOC concentrations and aromaticity were associated with lakes in watersheds with fine-textured surficial geology and with relatively large contributions through shallow, organic-rich flow paths. Lake DOC aromaticity was also higher in lakes with lower evaporative enrichment, regardless of surficial geology, indicating shorter lake water residence times and less within-lake degradation of allochthonous DOC. High inter-annual variability for both DOC and aromaticity was observed, with coefficients of variation at 10.9 ± 4.6% and 11.1 ± 2.5% among lakes, respectively. Inter-annual variability in DOC concentrations had low synchronicity among lakes, with patterns of variability linked to surficial geology and primarily responsive to short-term cumulative precipitation. Conversely, inter-annual variability in aromaticity had high synchronicity among lakes, driven by longer-term cumulative precipitation and shifts in lake water residence times. Our study shows it is necessary to consider lake hydrogeomorphic setting and climate to understand spatial and inter-annual variability in lake DOC characteristics and associated lake functions, and that Boreal Plains lakes have high climate sensitivity.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Concentration and chemical composition of dissolved organic carbon (DOC) influence several lake functions; greenhouse gas exchange, nutrient cycling, food webs, and water treatability. To assess spatial and inter-annual controls on DOC characteristics, 34 lakes were sampled annually for 8 years on the Boreal Plains, Western Canada—a region with heterogeneous surficial geology, and a sub-humid climate with pronounced inter-annual wet-dry periods. Large spatial variability in long-term average DOC concentration (10–49 mg C L−1) and aromaticity (SUVA254: 1.2–3.9 L mg−1 C m−1) among lakes was found. Higher DOC concentrations and aromaticity were associated with lakes in watersheds with fine-textured surficial geology and with relatively large contributions through shallow, organic-rich flow paths. Lake DOC aromaticity was also higher in lakes with lower evaporative enrichment, regardless of surficial geology, indicating shorter lake water residence times and less within-lake degradation of allochthonous DOC. High inter-annual variability for both DOC and aromaticity was observed, with coefficients of variation at 10.9 ± 4.6% and 11.1 ± 2.5% among lakes, respectively. Inter-annual variability in DOC concentrations had low synchronicity among lakes, with patterns of variability linked to surficial geology and primarily responsive to short-term cumulative precipitation. Conversely, inter-annual variability in aromaticity had high synchronicity among lakes, driven by longer-term cumulative precipitation and shifts in lake water residence times. Our study shows it is necessary to consider lake hydrogeomorphic setting and climate to understand spatial and inter-annual variability in lake DOC characteristics and associated lake functions, and that Boreal Plains lakes have high climate sensitivity.
Mo, Ruping; So, Rita; Brugman, Melinda; Mooney, Curtis; Lui, Anthony; Jakob, Matthias; Castellan, Armel; Vingarzan, Roxanne
Column Relative Humidity and Primary Condensation Rate as Two Useful Supplements to Atmospheric River Analysis Journal Article
In: Water Resources Research, vol. 57, no. 11, 2021.
@article{article1,
title = {Column Relative Humidity and Primary Condensation Rate as Two Useful Supplements to Atmospheric River Analysis},
author = {Ruping Mo and Rita So and Melinda Brugman and Curtis Mooney and Anthony Lui and Matthias Jakob and Armel Castellan and Roxanne Vingarzan},
doi = {10.1029/2021WR029678},
year = {2021},
date = {2021-11-22},
urldate = {2021-11-19},
journal = {Water Resources Research},
volume = {57},
number = {11},
abstract = {Landfalling atmospheric rivers (ARs) frequently trigger heavy and sometimes prolonged precipitation, especially in regions with favored orographic enhancement. The presence and strength of ARs are often described using the integrated water vapor (IWV) and the integrated vapor transport (IVT). However, the associated precipitation is not directly correlated with these two variables. Instead, the intensity of precipitation is mainly determined by the net convergence of moisture flux and the initial degree of saturation of the air column. In this study, a simple algorithm is proposed for estimating the heavy precipitation attributable to the IVT convergence. Bearing a strong resemblance to the Kuo-Anthes parameterization scheme for cumulus convection, the proposed algorithm calculates the large-scale primary condensation rate (PCR) as a proportion of the IVT convergence, with a reduction to account for the general moistening in the atmosphere. The amount of reduction is determined by the column relative humidity (CRH), which is defined as the ratio of IWV to its saturation counterpart. Our analysis indicates that the diagnosable PCR compares well to the forecast precipitation rate given by a numerical weather prediction model. It is also shown that the PCR in an air column with CRH urn:x-wiley:00431397:media:wrcr25616:wrcr25616-math-0001 0.50 is negligibly small. The usefulness of CRH and PCR as two complements to standard AR analysis is illustrated in three case studies. The potential application of PCR to storm classification is also explored.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Landfalling atmospheric rivers (ARs) frequently trigger heavy and sometimes prolonged precipitation, especially in regions with favored orographic enhancement. The presence and strength of ARs are often described using the integrated water vapor (IWV) and the integrated vapor transport (IVT). However, the associated precipitation is not directly correlated with these two variables. Instead, the intensity of precipitation is mainly determined by the net convergence of moisture flux and the initial degree of saturation of the air column. In this study, a simple algorithm is proposed for estimating the heavy precipitation attributable to the IVT convergence. Bearing a strong resemblance to the Kuo-Anthes parameterization scheme for cumulus convection, the proposed algorithm calculates the large-scale primary condensation rate (PCR) as a proportion of the IVT convergence, with a reduction to account for the general moistening in the atmosphere. The amount of reduction is determined by the column relative humidity (CRH), which is defined as the ratio of IWV to its saturation counterpart. Our analysis indicates that the diagnosable PCR compares well to the forecast precipitation rate given by a numerical weather prediction model. It is also shown that the PCR in an air column with CRH urn:x-wiley:00431397:media:wrcr25616:wrcr25616-math-0001 0.50 is negligibly small. The usefulness of CRH and PCR as two complements to standard AR analysis is illustrated in three case studies. The potential application of PCR to storm classification is also explored.
Porter, Mike
Conceptual Markov Models for Estimating Velocity Transition Probabilities for Landslides in the Western Canada Sedimentary Basin Conference
GeoNiagra 2021: Creating a sustainable and smart future, 2021.
@conference{Conference1,
title = {Conceptual Markov Models for Estimating Velocity Transition Probabilities for Landslides in the Western Canada Sedimentary Basin},
author = {Mike Porter},
year = {2021},
date = {2021-11-21},
urldate = {2021-09-26},
booktitle = {GeoNiagra 2021: Creating a sustainable and smart future},
abstract = {Landslides in the Western Canada Sedimentary Basin cause economic impacts that likely exceed $400 million per year. Most damage occurs where infrastructure crosses pre-existing landslides and when those landslides transition from adormant state or an extremely-slow (<16 mm/yr) velocity to more rapid velocities. Numerous factors can cause a change in velocity, correlations between those factors and velocity are imperfectly understood, and the future timing and condition of those factors are difficult to predict, confounding our attempts to predict the probability of landslide velocity transitions. A conceptual approach to the prediction of landslide velocity using Markov models is presented. The approach combines geomorphic evidence of long-term landslide behaviour with current estimates of landslide velocity to make probabilistic predictions of future velocity in the absence of other information. The model outputs could help improve risk-informed decision making for the planning and operation of infrastructure exposed to pre-existing landslide hazards.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Landslides in the Western Canada Sedimentary Basin cause economic impacts that likely exceed $400 million per year. Most damage occurs where infrastructure crosses pre-existing landslides and when those landslides transition from adormant state or an extremely-slow (<16 mm/yr) velocity to more rapid velocities. Numerous factors can cause a change in velocity, correlations between those factors and velocity are imperfectly understood, and the future timing and condition of those factors are difficult to predict, confounding our attempts to predict the probability of landslide velocity transitions. A conceptual approach to the prediction of landslide velocity using Markov models is presented. The approach combines geomorphic evidence of long-term landslide behaviour with current estimates of landslide velocity to make probabilistic predictions of future velocity in the absence of other information. The model outputs could help improve risk-informed decision making for the planning and operation of infrastructure exposed to pre-existing landslide hazards.
Sturzenegger, Matthieu; Holm, Kris; Lau, Carie-Ann; Jakob, Matthias
Debris-Flow and Debris-Flood Susceptibility Mapping for Geohazard Risk Prioritization Journal Article
In: Environmental and Engineering Geoscience, vol. 27, no. 2, pp. 179-194, 2021.
@article{articleb,
title = {Debris-Flow and Debris-Flood Susceptibility Mapping for Geohazard Risk Prioritization},
author = {Matthieu Sturzenegger and Kris Holm and Carie-Ann Lau and Matthias Jakob},
doi = {10.2113/EEG-D-20-00006},
year = {2021},
date = {2021-11-12},
urldate = {2021-11-04},
journal = {Environmental and Engineering Geoscience},
volume = {27},
number = {2},
pages = {179-194},
abstract = {Regional-scale assessments for debris-flow and debris-flood propagation and avulsion on fans can be challenging. Geomorphological mapping based on aerial or satellite imagery requires substantial field verification effort. Surface evidence of past events may be obfuscated by development or obscured by repeat erosion or debris inundation, and trenching may be required to record the sedimentary architecture and date past events. This paper evaluates a methodology for debris-flow and debris-flood susceptibility mapping at regional scale based on a combination of digital elevation model (DEM) metrics to identify potential debris source zones and flow propagation modeling using the Flow-R code that is calibrated through comparison to mapped alluvial fans. The DEM metrics enable semi-automated identification and preliminary, process-based classification of streams prone to debris flow and debris flood. Flow-R is a susceptibility mapping tool that models potential flow inundation based on a combination of spreading and runout algorithms considering DEM topography and empirical propagation parameters. The methodology is first evaluated at locations where debris-flow and debris-flood hazards have been previously assessed based on field mapping and detailed numerical modeling. It is then applied over a 125,000 km 2 area in southern British Columbia, Canada. The motivation for the application of this methodology is that it represents an objective and repeatable approach to susceptibility mapping, which can be integrated in a debris-flow and debris-flood risk prioritization framework at regional scale to support risk management decisions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Regional-scale assessments for debris-flow and debris-flood propagation and avulsion on fans can be challenging. Geomorphological mapping based on aerial or satellite imagery requires substantial field verification effort. Surface evidence of past events may be obfuscated by development or obscured by repeat erosion or debris inundation, and trenching may be required to record the sedimentary architecture and date past events. This paper evaluates a methodology for debris-flow and debris-flood susceptibility mapping at regional scale based on a combination of digital elevation model (DEM) metrics to identify potential debris source zones and flow propagation modeling using the Flow-R code that is calibrated through comparison to mapped alluvial fans. The DEM metrics enable semi-automated identification and preliminary, process-based classification of streams prone to debris flow and debris flood. Flow-R is a susceptibility mapping tool that models potential flow inundation based on a combination of spreading and runout algorithms considering DEM topography and empirical propagation parameters. The methodology is first evaluated at locations where debris-flow and debris-flood hazards have been previously assessed based on field mapping and detailed numerical modeling. It is then applied over a 125,000 km 2 area in southern British Columbia, Canada. The motivation for the application of this methodology is that it represents an objective and repeatable approach to susceptibility mapping, which can be integrated in a debris-flow and debris-flood risk prioritization framework at regional scale to support risk management decisions.
Jakob, Matthias
Debris-Flow Hazard Assessments: A Practitioner's View Journal Article
In: Environmental and Engineering Geoscience, vol. 27, no. 2, pp. 153–166, 2021.
@article{articleb,
title = {Debris-Flow Hazard Assessments: A Practitioner's View},
author = {Matthias Jakob},
doi = {10.2113/EEG-D-20-00110},
year = {2021},
date = {2021-11-04},
urldate = {2021-01-01},
journal = {Environmental and Engineering Geoscience},
volume = {27},
number = {2},
pages = {153–166},
abstract = {Substantial advances have been achieved in various aspects of debris-flow hazard assessments over the past decade. These advances include sophisticated ways to date previous events, two- and three-dimensional runout models including multi-phase flows and debris entrainment options, and applications of extreme value statistics to assemble frequency–magnitude analyses. Pertinent questions have remained the same: How often, how big, how fast, how deep, how intense, and how far? Similarly, although major life loss attributable to debris flows can often, but not always, be avoided in developed nations, debris flows remain one of the principal geophysical killers in mountainous terrains. Substantial differences in debris-flow hazard persist between nations. Some rely on a design magnitude associated with a specific return period; others use relationships between intensity and frequency; and some allow for, but do not mandate, in-depth quantitative risk assessments. Differences exist in the management of debris-flow risks, from highly sophisticated and nation-wide applied protocols to retroaction in which catastrophic debris flows occur before they are considered for mitigation. Two factors conspire to challenge future generations of debris-flow researchers, practitioners, and decision makers: Population growth and climate change, which are increasingly manifested by augmenting hydroclimatic extremes. While researchers will undoubtedly finesse future remote sensing, dating, and runout techniques and models, practitioners will need to focus on translating those advances into practical cost-efficient tools and integrating those tools into long-term debris-flow risk management.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Substantial advances have been achieved in various aspects of debris-flow hazard assessments over the past decade. These advances include sophisticated ways to date previous events, two- and three-dimensional runout models including multi-phase flows and debris entrainment options, and applications of extreme value statistics to assemble frequency–magnitude analyses. Pertinent questions have remained the same: How often, how big, how fast, how deep, how intense, and how far? Similarly, although major life loss attributable to debris flows can often, but not always, be avoided in developed nations, debris flows remain one of the principal geophysical killers in mountainous terrains. Substantial differences in debris-flow hazard persist between nations. Some rely on a design magnitude associated with a specific return period; others use relationships between intensity and frequency; and some allow for, but do not mandate, in-depth quantitative risk assessments. Differences exist in the management of debris-flow risks, from highly sophisticated and nation-wide applied protocols to retroaction in which catastrophic debris flows occur before they are considered for mitigation. Two factors conspire to challenge future generations of debris-flow researchers, practitioners, and decision makers: Population growth and climate change, which are increasingly manifested by augmenting hydroclimatic extremes. While researchers will undoubtedly finesse future remote sensing, dating, and runout techniques and models, practitioners will need to focus on translating those advances into practical cost-efficient tools and integrating those tools into long-term debris-flow risk management.
Mitchell, Andrew; McDougall, Scott; Aaron, Jordan; Brideau, Marc-Andre
Development of a Universal Open Access Rock Avalanche Case Study Database Conference
International Symposium on Landslides, 2021.
@conference{Conference1,
title = {Development of a Universal Open Access Rock Avalanche Case Study Database },
author = {Andrew Mitchell and Scott McDougall and Jordan Aaron and Marc-Andre Brideau},
year = {2021},
date = {2021-11-03},
urldate = {2021-02-01},
booktitle = {International Symposium on Landslides},
abstract = {Predicting the post-failure behavior of complex events such as rock avalanches often involves looking at past events to make inferences about potential future events. Many case studies of rock avalanches have been published, but a consistent methodology for describing these events has not been universally adopted. Furthermore, geohazard researchers and practitioners must go through many publications to find details on a sufficient number of events to make inferences on factors that may be controlling runout characteristics. An open access database has been developed that contains the digitized impact areas, descriptive attributes, and bibliographic references for a large number of events. This open access database has recently been used to develop new empirical relationships for travel distance and impacted area. Where available, information about the coarse rocky debris and mobilized sediments of the rock avalanche deposit are provided. The attributes within the database have been selected to be simple enough that they can be consistently assigned by different users and to maximize sample sizes, while still being able to separate out factors that have been demonstrated to influence rock avalanche mobility. The database is intended not only to make the existing spatial and descriptive information on these events available, but to allow for other researchers and practitioners to share data in a consistent format. By collaboratively building a universal, open access database of events, greater insights into the controls on rock avalanche mobility, including potential regional trends, may eventually be gained.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Predicting the post-failure behavior of complex events such as rock avalanches often involves looking at past events to make inferences about potential future events. Many case studies of rock avalanches have been published, but a consistent methodology for describing these events has not been universally adopted. Furthermore, geohazard researchers and practitioners must go through many publications to find details on a sufficient number of events to make inferences on factors that may be controlling runout characteristics. An open access database has been developed that contains the digitized impact areas, descriptive attributes, and bibliographic references for a large number of events. This open access database has recently been used to develop new empirical relationships for travel distance and impacted area. Where available, information about the coarse rocky debris and mobilized sediments of the rock avalanche deposit are provided. The attributes within the database have been selected to be simple enough that they can be consistently assigned by different users and to maximize sample sizes, while still being able to separate out factors that have been demonstrated to influence rock avalanche mobility. The database is intended not only to make the existing spatial and descriptive information on these events available, but to allow for other researchers and practitioners to share data in a consistent format. By collaboratively building a universal, open access database of events, greater insights into the controls on rock avalanche mobility, including potential regional trends, may eventually be gained.
Pokharel, Bigul; Siddiqua, Sumi
Effect of Calcium Bentonite Clay and Fly Ash on the Stabilization of Organic Soil from Alberta, Canada Journal Article
In: Engineering Geology, vol. 293, 2021.
@article{article1,
title = {Effect of Calcium Bentonite Clay and Fly Ash on the Stabilization of Organic Soil from Alberta, Canada},
author = {Bigul Pokharel and Sumi Siddiqua},
doi = {10.1016/j.enggeo.2021.106291},
year = {2021},
date = {2021-10-31},
urldate = {2021-10-31},
journal = {Engineering Geology},
volume = {293},
abstract = {This paper presents findings of the effect of calcium bentonite (Ca-bentonite) and pulp mill fly ash (PFA) on the compressibility behavior, and microstructural evolution of organic soil. A natural soil consisting of 26% organic matter was collected from the wetlands in the Wabasca region, Northern Alberta, Canada. A various mix design was prepared for the laboratory tests with the addition of 5%, 8%, 10%, 12%, 15%, and 20% Ca-bentonite with constant 30% PFA. One-dimensional consolidation tests were carried out to evaluate compressibility behavior of the stabilized organic soil. In addition, fall cone tests were conducted to evaluate change in undrained shear strength of soil after stabilization. A series of scanning electron microscope (SEM) tests with energy dispersive X-ray (EDS) and X-ray diffraction (XRD) experiments were conducted to investigate the microstructural and chemical aspects of the organic soil treated with Ca-bentonite and PFA. The results showed that a mixture of 10% Ca-bentonite with 30% PFA was the optimum dosage for improving compressibility of organic soil regardless of the curing method. Microstructural and chemical analysis revealed that the mineralogical and morphological contents of the stabilized organic soil were affected due to the pozzolanic reaction. The results showed that Ca-bentonite and PFA were able to considerably improve the strength and compressibility of the selected organic soil.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This paper presents findings of the effect of calcium bentonite (Ca-bentonite) and pulp mill fly ash (PFA) on the compressibility behavior, and microstructural evolution of organic soil. A natural soil consisting of 26% organic matter was collected from the wetlands in the Wabasca region, Northern Alberta, Canada. A various mix design was prepared for the laboratory tests with the addition of 5%, 8%, 10%, 12%, 15%, and 20% Ca-bentonite with constant 30% PFA. One-dimensional consolidation tests were carried out to evaluate compressibility behavior of the stabilized organic soil. In addition, fall cone tests were conducted to evaluate change in undrained shear strength of soil after stabilization. A series of scanning electron microscope (SEM) tests with energy dispersive X-ray (EDS) and X-ray diffraction (XRD) experiments were conducted to investigate the microstructural and chemical aspects of the organic soil treated with Ca-bentonite and PFA. The results showed that a mixture of 10% Ca-bentonite with 30% PFA was the optimum dosage for improving compressibility of organic soil regardless of the curing method. Microstructural and chemical analysis revealed that the mineralogical and morphological contents of the stabilized organic soil were affected due to the pozzolanic reaction. The results showed that Ca-bentonite and PFA were able to considerably improve the strength and compressibility of the selected organic soil.
Walsh, Andrea; McDougall, Scott; Evans, Stephen; Take, Andy
In: Water Resources Research, vol. 57, no. 12, 2021.
@article{article1,
title = {Effect of Upstream Dam Geometry on Peak Discharge During Overtopping Breach in Noncohesive Homogeneous Embankment Dams; Implications for Tailings Dams},
author = {Andrea Walsh and Scott McDougall and Stephen Evans and Andy Take},
doi = {10.1029/2020WR029358},
year = {2021},
date = {2021-10-29},
urldate = {2021-10-31},
journal = {Water Resources Research},
volume = {57},
number = {12},
abstract = {Tailings dams differ from conventional water-retaining dams in design, materials retained behind the dam and used in construction of the dam, and the inclination of the upstream face of the dam. In this paper, we isolate the effect of upstream slope angle on behavior during overtopping breach. Six 1 m high homogeneous fine sand dams were constructed with upstream slope angles varying between 10.0° and 30.0° and brought to failure by V notch overtopping. Slope angle was observed to define the height of flow over the erosional breach crest hydraulic control structure that forms in the upstream face of the dam, with higher peak outflow corresponding to steeper upstream slope angles. A semiellipse was observed to be an excellent approximation of the geometry of the breach throughout the rising limb of the hydrograph to peak outflow. This observation permitted the use of the Ramanujan approximation for perimeter of an ellipse to define a mathematical relationship between breach width and arc length. A simplified method to predict the rising limb of the outflow hydrograph was then proposed based on the assumption of linear growth of breach width coupled with a semielliptical breach geometry. These findings show that hazard analysis for overtopping failure should consider the effect of upstream slope angle on peak outflow.
Plain Language Summary
Dam breach is the failure of a dam structure resulting in the uncontrolled release of the material retained behind the dam in a sudden or catastrophic manner. The outflow hydrograph, defined as the time rate of material released from the dam, is used in computer models to predict of how far, how fast, and how deep inundation will occur. Tailings are waste products of the mining industry generally produced by crushing and grinding rock to extract valuable minerals. Tailings dams differ from water-retaining dams in design, materials retained and used in construction of the dam, and the inclination of the upstream face of the dam. In this paper, we isolate the effect of upstream slope angle on behavior during overtopping breach. Six 1 m high homogeneous fine sand dams with upstream slope angles varying between 10.0° and 30.0° were breached by water overtopping. The upstream slope angle was observed to define the height of flow over the erosional weir that forms in the upstream face of the dam, with higher peak outflow corresponding to steeper upstream slope angles. These findings show that hazard analysis for overtopping failure should consider the effect of upstream slope angle on peak outflow.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Tailings dams differ from conventional water-retaining dams in design, materials retained behind the dam and used in construction of the dam, and the inclination of the upstream face of the dam. In this paper, we isolate the effect of upstream slope angle on behavior during overtopping breach. Six 1 m high homogeneous fine sand dams were constructed with upstream slope angles varying between 10.0° and 30.0° and brought to failure by V notch overtopping. Slope angle was observed to define the height of flow over the erosional breach crest hydraulic control structure that forms in the upstream face of the dam, with higher peak outflow corresponding to steeper upstream slope angles. A semiellipse was observed to be an excellent approximation of the geometry of the breach throughout the rising limb of the hydrograph to peak outflow. This observation permitted the use of the Ramanujan approximation for perimeter of an ellipse to define a mathematical relationship between breach width and arc length. A simplified method to predict the rising limb of the outflow hydrograph was then proposed based on the assumption of linear growth of breach width coupled with a semielliptical breach geometry. These findings show that hazard analysis for overtopping failure should consider the effect of upstream slope angle on peak outflow.
Plain Language Summary
Dam breach is the failure of a dam structure resulting in the uncontrolled release of the material retained behind the dam in a sudden or catastrophic manner. The outflow hydrograph, defined as the time rate of material released from the dam, is used in computer models to predict of how far, how fast, and how deep inundation will occur. Tailings are waste products of the mining industry generally produced by crushing and grinding rock to extract valuable minerals. Tailings dams differ from water-retaining dams in design, materials retained and used in construction of the dam, and the inclination of the upstream face of the dam. In this paper, we isolate the effect of upstream slope angle on behavior during overtopping breach. Six 1 m high homogeneous fine sand dams with upstream slope angles varying between 10.0° and 30.0° were breached by water overtopping. The upstream slope angle was observed to define the height of flow over the erosional weir that forms in the upstream face of the dam, with higher peak outflow corresponding to steeper upstream slope angles. These findings show that hazard analysis for overtopping failure should consider the effect of upstream slope angle on peak outflow.
Plain Language Summary
Dam breach is the failure of a dam structure resulting in the uncontrolled release of the material retained behind the dam in a sudden or catastrophic manner. The outflow hydrograph, defined as the time rate of material released from the dam, is used in computer models to predict of how far, how fast, and how deep inundation will occur. Tailings are waste products of the mining industry generally produced by crushing and grinding rock to extract valuable minerals. Tailings dams differ from water-retaining dams in design, materials retained and used in construction of the dam, and the inclination of the upstream face of the dam. In this paper, we isolate the effect of upstream slope angle on behavior during overtopping breach. Six 1 m high homogeneous fine sand dams with upstream slope angles varying between 10.0° and 30.0° were breached by water overtopping. The upstream slope angle was observed to define the height of flow over the erosional weir that forms in the upstream face of the dam, with higher peak outflow corresponding to steeper upstream slope angles. These findings show that hazard analysis for overtopping failure should consider the effect of upstream slope angle on peak outflow.
Sharma, Keshab; Deng, Lijun
Effects of Loading Obliquity on Field Performance of Rocking Shallow Foundations in Cohesive Soil Journal Article
In: Géotechnique, vol. 71, no. 4, pp. 320-333, 2021.
@article{article1,
title = {Effects of Loading Obliquity on Field Performance of Rocking Shallow Foundations in Cohesive Soil},
author = {Keshab Sharma and Lijun Deng},
doi = {10.1680/jgeot.19.p.033},
year = {2021},
date = {2021-10-27},
urldate = {2021-10-26},
journal = {Géotechnique},
volume = {71},
number = {4},
pages = {320-333},
abstract = {This paper presents a field study of obliquely loaded rocking shallow foundations resting on cohesive soil. Lateral snap-back and cyclic loading tests at an oblique angle of 45° with respect to the footing axes were carried out. During the snap-back tests, an initial drift ratio was applied to the deck and then the system was released to enable the free vibration. The cyclic loading consisted of five packets containing three to four cycles of similar displacement amplitude. The rocking system consisted of a 1·5 m by 1·0 m concrete footing, steel column and deck. The factors of safety against bearing failure were varied from 4 to 20. It was observed that the system primarily rocked in plane. The moment capacities about footing axes deviated from the calculated values at the orthogonal loading conditions. A method of estimating the rocking moment capacity of a footing subjected to oblique loading was developed and validated by the tests. Natural periods, damping ratio, re-centring ratio, settlement and stiffness degradation during the tests are discussed and compared with the results from previous studies with orthogonal loading. The soil–footing contact area was approximately triangular. A method of calculating the critical contact area was developed based on the bearing capacity theory with two-way eccentricity and then confirmed by observation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This paper presents a field study of obliquely loaded rocking shallow foundations resting on cohesive soil. Lateral snap-back and cyclic loading tests at an oblique angle of 45° with respect to the footing axes were carried out. During the snap-back tests, an initial drift ratio was applied to the deck and then the system was released to enable the free vibration. The cyclic loading consisted of five packets containing three to four cycles of similar displacement amplitude. The rocking system consisted of a 1·5 m by 1·0 m concrete footing, steel column and deck. The factors of safety against bearing failure were varied from 4 to 20. It was observed that the system primarily rocked in plane. The moment capacities about footing axes deviated from the calculated values at the orthogonal loading conditions. A method of estimating the rocking moment capacity of a footing subjected to oblique loading was developed and validated by the tests. Natural periods, damping ratio, re-centring ratio, settlement and stiffness degradation during the tests are discussed and compared with the results from previous studies with orthogonal loading. The soil–footing contact area was approximately triangular. A method of calculating the critical contact area was developed based on the bearing capacity theory with two-way eccentricity and then confirmed by observation.
van der Velde, Ype; Temme, Arnaud; Nijp, Jelmer; Braakhekke, Maarten; van Voorn, George; Dekker, Stefan; Dolman, Johannes; Wallinga, Jakob; Devito, Kevin; Kettridge, Nicholas; Mendoza, Carl; Kooistra, Lammert; Soons, Merel; Teuling, Adriaan
Emerging Forest-Peatland Bistability and Resilience of European Peatland Carbon Stores Journal Article
In: Proceedings of the National Academy of Sciences, vol. 118, no. 38, 2021.
@article{journal1,
title = {Emerging Forest-Peatland Bistability and Resilience of European Peatland Carbon Stores},
author = {Ype van der Velde and Arnaud Temme and Jelmer Nijp and Maarten Braakhekke and George van Voorn and Stefan Dekker and Johannes Dolman and Jakob Wallinga and Kevin Devito and Nicholas Kettridge and Carl Mendoza and Lammert Kooistra and Merel Soons and Adriaan Teuling},
doi = {10.1073/pnas.2101742118},
year = {2021},
date = {2021-10-24},
urldate = {2021-10-15},
journal = {Proceedings of the National Academy of Sciences},
volume = {118},
number = {38},
abstract = {Northern peatlands store large amounts of carbon. Observations indicate that forests and peatlands in northern biomes can be alternative stable states for a range of landscape settings. Climatic and hydrological changes may reduce the resilience of peatlands and forests, induce persistent shifts between these states, and release the carbon stored in peatlands. Here, we present a dynamic simulation model constrained and validated by a wide set of observations to quantify how feedbacks in water and carbon cycling control resilience of both peatlands and forests in northern landscapes. Our results show that 34% of Europe (area) has a climate that can currently sustain existing rainwater-fed peatlands (raised bogs). However, raised bog initiation and restoration by water conservation measures after the original peat soil has disappeared is only possible in 10% of Europe where the climate allows raised bogs to initiate and outcompete forests. Moreover, in another 10% of Europe, existing raised bogs (concerning ∼20% of the European raised bogs) are already affected by ongoing climate change. Here, forests may overgrow peatlands, which could potentially release in the order of 4% (∼24 Pg carbon) of the European soil organic carbon pool. Our study demonstrates quantitatively that preserving and restoring peatlands requires looking beyond peatland-specific processes and taking into account wider landscape-scale feedbacks with forest ecosystems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Northern peatlands store large amounts of carbon. Observations indicate that forests and peatlands in northern biomes can be alternative stable states for a range of landscape settings. Climatic and hydrological changes may reduce the resilience of peatlands and forests, induce persistent shifts between these states, and release the carbon stored in peatlands. Here, we present a dynamic simulation model constrained and validated by a wide set of observations to quantify how feedbacks in water and carbon cycling control resilience of both peatlands and forests in northern landscapes. Our results show that 34% of Europe (area) has a climate that can currently sustain existing rainwater-fed peatlands (raised bogs). However, raised bog initiation and restoration by water conservation measures after the original peat soil has disappeared is only possible in 10% of Europe where the climate allows raised bogs to initiate and outcompete forests. Moreover, in another 10% of Europe, existing raised bogs (concerning ∼20% of the European raised bogs) are already affected by ongoing climate change. Here, forests may overgrow peatlands, which could potentially release in the order of 4% (∼24 Pg carbon) of the European soil organic carbon pool. Our study demonstrates quantitatively that preserving and restoring peatlands requires looking beyond peatland-specific processes and taking into account wider landscape-scale feedbacks with forest ecosystems.
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