EGU24-22543, updated on 18 Apr 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Quantifying snow water storage from aerial LiDAR surveys in eight Pacific coastal watersheds, British Columbia, Canada

Rosie Bisset1,2, Bill Floyd1,3, Brian Menounos1, Alison Bishop1,2, Sergey Marchenko1,2, Peter Marshall4, and Hakai Geospatial5
Rosie Bisset et al.
  • 1University of Northern British Columbia, Department of Geography, Earth and Environmental Sciences, Prince George, BC, Canada
  • 2Vancouver Island University, Coastal Hydrology Research Laboratory, Nanaimo, BC, Canada
  • 3British Columbia Ministry of Forests, Nanaimo, BC, Canada
  • 4Metro Vancouver, Vancouver, BC, Canada
  • 5Hakai Institute, Campbell River, BC, Canada

While airborne Light Detection and Ranging (LiDAR) surveys are routinely used to measure snow volume in many types of mountain watersheds, those that are heavily forested and lie within maritime environments have been largely ignored to date. Here, we summarise our findings from a four-year study (2020-2023) of eight watersheds within the coastal rainforests of southwest British Columbia, which collectively represent an area of >330 km2. Aerial LiDAR surveys were conducted 3 to 5 times per year between March and June in order to measure snow depth across each watershed. Spatiotemporally-distributed snow density was estimated using a random forest model incorporating weather station data, LiDAR-derived metrics and in-situ snow density observations. At peak snow volume, we find typical mean catchment-wide snow water equivalent values of ~600-1200 mm, verified by a widespread field campaign consisting of > 25,000 in-situ measurements of snow depth and density. We show that, typically, ~60-90 % of the snow water volume is stored at mid-elevations of between 800 and 1500 m, where air temperatures are close to melting point and forest cover is prevalent, leaving the snowpack vulnerable to early seasonal melt onset and impacts due to forest management. We find that while peak measured snow volume typically represents ~20-40 % of surface runoff, providing an important buffer towards droughts within the region, snowmelt volumes can be insufficient to safeguard downstream water supply during extreme seasonal drought events. Overall, the results of this work provide valuable insights into the vulnerability of the snowpack in coastal maritime regions and the potential knock-on effects of a changing snowpack on regional water security.

How to cite: Bisset, R., Floyd, B., Menounos, B., Bishop, A., Marchenko, S., Marshall, P., and Geospatial, H.: Quantifying snow water storage from aerial LiDAR surveys in eight Pacific coastal watersheds, British Columbia, Canada, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22543,, 2024.