Location: Water Management and Systems Research
Project Number: 3012-13660-010-016-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 1, 2023
End Date: May 31, 2025
Objective:
ARS will investigate the response of runoff to rainfall events in mulched and unmulched catchments in northern Colorado.
Approach:
Aerial applications of mulch have been conducted in Colorado Front Range fires to reduce sedimentation and flood risk. Prior research has examined effectiveness of mulch applications for reducing runoff and erosion at plot to hillslope scale, but water managers need to know whether these effects are also evident downstream in catchments and larger watersheds. We have installed rainfall and streamflow monitoring in catchments within the burned areas of the 2020 Cameron Peak and East Troublesome fires. In Cameron Peak, the monitored catchments are six adjacent tributaries to Bennett Creek. Three of these catchments were mulched in 2021, and the other three were not treated with mulch. There are 1-2 tipping buckets per catchment, with at least one located near capacitance rods in the stream channel to observe streamflow stage. In East Troublesome fire, the 11 monitored catchments are tributaries to Willow Creek. Two are unburned; four are burned and unmulched, and five are burned and mulched. In both fires we will compare rainfall estimates across the monitored catchments using tipping bucket and radar data. We will also use radar data (multi-radar/multi-sensor; MRMS) to better characterize spatial variability in storm precipitation amounts and intensity. Precipitation data and stage data will be combined with catchment physical characteristics in a logistic regression model to assess thresholds for runoff events and how they may be buffered by catchment characteristics such as slope angle, aspect, surface roughness, and mulch cover.
