Water Resources Research Act Program

Details for Project ID CO-2023-R04

Geomorphic factors influencing post-wildfire fluvial response

Institute: Colorado
Year Established: 2023 Start Date: 2023-09-01 End Date: 2024-08-31
Total Federal Funds: $9,982 Total Non-Federal Funds: $34,212

Principal Investigators: Wohl

Project Summary: Little Beaver Creek (LBC) and Black Hollow (BH) are two geographically comparable mountain watersheds in the Front Range that burned at similar severity and extent in the 2020 Cameron Peak fire. Both watersheds experienced debris flows triggered by convective storms during Summer 2021 and 2022, respectively. The BH debris flow followed the channel down to the mainstem Cache la Poudre River (Poudre), resulting in four fatalities, fish kill and water quality degradation along the entire downstream length of the Poudre, and extensive sedimentation on an alluvial fan1. LBC had a smaller debris flow that entered the mainstem creek via a tributary and was contained within the watershed. Based on export of sediment from each watershed, and loss of life and property, I posit that BH was less resilient to post-fire disturbance than LBC. I hypothesize that (H1) Little Beaver Creek has greater longitudinal and intra-reach heterogeneity than Black Hollow and (H2) the magnitude and spatial distribution of heterogeneity in each river corridor correlate inversely with post-fire sediment export from the watershed. I will test the hypotheses using both remote sensing data and field measurements. Insights from this research can be used to manage streams in ways that increase resilience to wildfire and associated disturbances such as debris flows.