Using lidar change detection to support the flooding recovery efforts in British Columbia

In November of 2021, southwestern British Columbia, Canada and northwestern Washington State were affected by a series of atmospheric rivers that caused widespread geohazards and destruction of critical infrastructure. This weather event resulted in massive precipitation leading to flooding, landslides, and debris slides that impacted many communities. Highways, pipelines, energy transmission lines, and railways all experienced damage and were inoperable – at the date of writing, some still are.

In the immediate aftermath of the event, BGC worked collaboratively with our clients to develop an understanding of the damage and chart a path to recovery. One of the many techniques we deployed was regional scale three-dimensional lidar change detection. Numerical processing can be used to quickly identify and visualize areas of topographic change where multiple lidar datasets are available for the same areas. In the case of the British Columbia atmospheric river events, BGC used airborne lidar scanning change detection to find and quantify the resulting geohazard activity, which took the form of landslides, flooding, bank erosion, and debris slides.

Working closely with our partners at McElhanney, we collected over 500 square kilometres of airborne lidar scanning data between Hope, BC and Merritt, BC. The post- atmospheric rivers data was compared to earlier datasets available from prior work for clients in the area. BGC was able to deliver digital change detection results within hours of receiving the lidar data from McElhanney using our patent processing method (patent has been allowed and is currently in the process of being granted). Results were immediately available to our clients and their partners through Cambio, our secure online platform, to support in recovery efforts. The resulting data was used to identify impacts on assets, prioritize field inspections, develop new designs, and understand future risks.

In the past year we have processed over 50,000 square kilometres of lidar change detection data, serving up tens of billions of lidar change detection points in Cambio to clients globally. We are proud that this work has been able to rapidly deliver high-value information used to save lives, reduce costs, and protect the environment.

Matthew Lato, PD.D., Eng., P.Eng. (AB, BC, ON, SK)

Innovation Lead

Matthew Lato is a Senior Engineer at BGC. His technical expertise is in the application of 3-dimensional remote sensing, specifically LiDAR and photogrammetry, for geotechnical mapping, change detection monitoring, and stability assessment and geohazard risk management. He is the lead author of the Site Investigation, Analysis, Monitoring and Treatment chapter of the Canadian Technical Guidelines and Best Practices related to Landslides, the recipient of the 2018 Canadian Geotechnical Colloquium Award, and an author or co-author of over 31 journal papers and 90 conference papers.

Employee Spotlight – Chelsea Simpson

Chelsea Simpson’s first job out of university was with BGC in our Calgary office. She was born and raised in the Northwest Territories in Canada and found her way to Calgary to attend university but had always intended to return home. When she started with BGC, she thought that she would be here for 1 year and then move on. Fast forward nine years and she is still here at BGC with the only difference is that she found her way back home to the NWT.

Chelsea originally went to university for sociology as she has always been interested in the social stratification of Indigenous peoples in Canada, and particular for Indigenous women.

When she initially joined BGC she had never heard of geotechnical or geological engineering and came in not knowing much about it. When she initially joined BGC she had never heard of geotechnical or geological engineering and came in not knowing much about it. She will tell you that the passion that BGCers have for their work really got to her and she realized that working at BGC was a place she wanted to grow her career. She appreciates the fact that she comes to work everyday to be around people she truly wants to work with. As she’s grown in her profession over the years, she credits the Office Managers she’s worked with as pushing her in directions she didn’t know she was capable of and being super supportive of her professional journey here.

How long have you been with BGC and what do you do here?

I’ve been with BGC almost 9 years and I work as an Administrator, these days mostly supporting the wider Admin Team and helping with office moves and renovations. I’m still officially part of the Calgary office but I work remotely from Yellowknife.

How would you describe your job to a class of Kindergartners?

How do you put all the millions of things an administrator does into one succinct description? I think I would say that lots of times my job is to listen to people and help them feel better about what they’re doing. I help people with the parts of their job that I’m good at, so that they can pay attention to the parts of their job that they’re really good at.

What is your favourite thing about working at BGC?

You have flexibility at BGC and you can take your job into whatever direction you are passionate about; there are no formal scopes that dictate that you can only work in a particular area. I like that they have enough trust in their employees to allow them to take the path their interested in.

What is the one piece of advice you’d give to new hires at BGC?

Talk to people and ask questions. When you start someone new, people always say they are open to questions and to help when it may not always be true, but at BGC when people say to ask question or come to them for help they genuinely mean it. I find that the more you talk to people that work in different areas here, the more you learn about BGC.

If you could switch jobs with someone in BGC, who would it be and why?

Sophol Tran who works in GIS. We started at the same time, I’m still not 100% sure I know what he does but would really like to figure out those Plains centreline updates. I would also be interested in switching with one of the librarians. I have spent lots of time working in local libraries and so I’d like to see what working as a librarian at a business would be like.

If you could have an unlimited supply of one thing, what would it be?

Books. Books are my happy place and a prefer them over movies or TV. I recently read The Strangers by Katherena Vermette, an Indigenous Canadian author. She also wrote another book a loved called The Break. I highly recommended both those books to anyone.

What is the weirdest food you’ve ever eaten?

This is not necessarily a weird food but probably shouldn’t be a food – Cheez Whiz. I love it and am only slightly embarrassed to admit it. Cheez Whiz on toast is one of my ultimate comfort foods.

What fictional place would you like to visit?

Willy Wonka’s Chocolate Factory and specifically the Gene Wilder movie version. It’s one of the few movies I can watch over and over again and I love every twisted, delicious, imaginative thing about it and would totally want to take a boat ride through the tunnel, and test whether I’d go down the good or bad egg chute.

If you had to listen to one song for the rest of your life what would it be?

Anything by Digable Planets.

What is the best advice you’ve ever been given?

My dad, from very young age, instilled in us to say what you think and stand up to what you believe in even if others don’t agree. It’s not always comfortable, but I try my best to practice that and even if the outcome isn’t what you want, at least you tried.

Employee Spotlight – Erin Olauson

Erin Olauson never thought she’d be doing the job she’s doing now when she was growing up. Born and raised in Saskatoon, SK, she thought she was going to be a geologist but ended up in engineering. In one of her first jobs, she spent two years drilling and test pitting almost every day. She was immersed in it and the idea of figuring out what you can do with the dirt. Her love for what she does grew from there.

Erin’s career took her to Vancouver for a number of years and then she moved to Calgary, where she’s lived for over 10 years. She cites one of the reasons she joined BGC was to work with some of the experts in her field that are part of our team. She’ll tell you, half jokingly, that she has never worked at a place where people are so happy to be at work. 

How long have you been with BGC and what do you do here?
I joined in the fall of 2015 and having been working in the Mining sector, and for the past several years on the design and construction of an oil sands tailing facility.

How would you describe your job to a class of Kindergartners?
Early on in my career I was trying to explain to my five-year-old nephew what I do for work. After I finished this long explanation, trying to simplify it as much as possible, he looked at me and said, “you’re a digger”. So yes, I’m a digger.

What is your favourite thing about working at BGC?
We have such open communication here at BGC. By that I mean it doesn’t matter what level you are, what you do, if you’re located in another office or another country, everyone is willing to help you. Even if you haven’t had the chance to work with the person or even interact with them before, everyone is willing to share their expertise.

What is the one piece of advice you’d give to new hires at BGC?
Pick up the phone. Of course, we don’t really pick up phones anymore, but as I mentioned above, it’s so open here so if you need help, send someone a quick note or ask to grab a coffee. And this can be anything, a technical question or looking for mentorship or advice. Don’t be afraid to reach out.

If you could switch jobs with someone in BGC, who would it be and why?
I’ve only had the opportunity to work in the Mining sector. But when we were able to be in the office together (pre-COVID), I’d often hear colleagues who work in the Pipeline sector share field stories. They always start off sounding like it’s so miserable, they’re trudging through mud and swamps and there are mosquitos everywhere, but they’re always telling the story with a smile on their faces and saying how much fun they had hiking around with their field partner all day. So my answer is a pipeline inspector.  Hiking around with my field partner all day sounds like fun despite the mud and mosquitos.

If you could have an unlimited supply of one thing, what would it be?
Succulent plants. I’ve start collecting plants as a COVID hobby. I love picking these small little succulent plants and watching them grow.

What is the weirdest food you’ve ever eaten?
Honestly, I’m not adventurous with food at all. If you ask other BGCers in the Calgary office about this, they’ll tell you that when we go to the pub near the office, I order the same thing every time.

What fictional place would you like to visit?
I love Superman comics, so I’d say Metropolis. I would go hang out by a phonebooth to see if I can meet Superman.

If you had to listen to one song for the rest of your life what would it be?
50 Mission Cap by the Tragically Hip

What is the best advice you’ve ever been given?
Set expectations. Set expectations for yourself so you can hopefully meet your own goals. And set expectations for others. How can you possibly expect someone to deliver a product when you haven’t told them what you want?

Using lidar data to inform risk management decisions

In August 2020, the Grizzly Creek Fire ignited in the rugged Glenwood Canyon of central Colorado. Glenwood Canyon is considered one of the most scenic corridors on the U.S. Interstate Highway System and is a critical route for road and rail traffic across the state as well as providing recreation opportunities for hiking, biking, hunting, and river rafting. Over an approximate four-month period the fire altered forest lands along the steep canyon walls and forested connecting drainages above Interstate 70 (I-70) and the Colorado River.

The following winter provided a quiet recovery period for the canyon, but this was only temporary as the summer months in this region of Colorado generate intense thunderstorms with runoff that can overwhelm heathy drainages. Unfortunately following a forest fire, the storm runoff on burned and bare soils can be orders of magnitude more destructive. The summer monsoon season of 2021 was no exception, with several storms generating sediment laden post-wildfire debris flows that covered and damaged I-70 and the nearby Amtrak railway, deposited sediment in the Colorado River, and also stranded travelers in the canyon at times. The events resulted in weeks of highway closure for this critical corridor during the summer travel season, causing adverse economic impacts to nearby communities and measurable disruptions to interstate commerce.

Post-fire debris flow blocking the Colorado River.

To reduce the potential for future disruptions, the Colorado Department of Transportation (CDOT) engaged with BGC to understand how ground conditions are changing following the wildfire and 2021 post-fire debris flows. Through this additional understanding, CDOT can prioritize mitigation projects on the basis of greatest need and cost-benefit, while also advancing predictive models that consider the relationship between burned conditions, slope, changes in terrain, and precipitation thresholds that can lead to disruptive debris flows.

Debris flow deposition on I-70 bridge approach.

To measure continuous ground change over the entire burn area, BGC contracted with an aerial survey firm to collect and process airborne lidar for over 100 square miles (260 square kilometers) of the Glenwood Canyon and Grizzly Creek Fire area. This newly collected lidar data was processed against existing public lidar data collected in 2016. These two sets of lidar data were entered into Cambio, BGC’s software platform, to deliver an interactive lidar change detection layer across the entire burn area. This processing of change between two different lidar data sets uses a patent-pending change detection algorithm to calculate positive and negative change over this entire area. Using Cambio, this type of change detection processing can be turned around within 24 hours.

Cambio screenshot showing the ground movements following storms in the Grizzly Burn Area.

BGC continues to work with CDOT and other partner agencies, such as the United States Geological Survey, to understand how the Canyon slopes have changed after the fire and 2021 debris flow season, and to plan mitigation efforts that can be implemented in the summer of 2022 and beyond. A better understanding of the post-fire debris flow events in Glenwood Canyon may also help CDOT and other stakeholders understand their risk exposure to debris flow impacts from future burn scars.

The Geohazards paradigm is so different to what a lot of the other members of CDOT are used to being exposed to. It is often difficult to convey the severity of an event to people outside of the response, but Cambio is such a great tool to do this alongside the other utility it provides.

BEAU Taylor
Colorado Department of Transportation
Close-up Cambio screenshot showing measurement of sediment loss and deposition in the Blue Gulch Basin of Glenwood Canyon.

Mark Vessely, M.Sc., PE.

Principal Geotechnical Engineer

Mark Vessely has over 25 years of experience in geologic hazard and risk assessment, emergency response to slope and other ground movements, and design for bridge foundations, retaining walls, pavements, and slope stabilization projects.