Measurement of post-fire hillslope erosion to evaluate and model rehabilitation treatment effectiveness and recovery

The increasing size and severity of wildfires in the western United States has caused a corresponding increase in post-fire emergency erosion control activities. Hillslope treatments, such as broadcast seeding, mulching and installed barriers, are applied to reduce runoff and erosion, as well as downslope sedimentation. However, there are few data to determine if these post-fire treatments are practical and effective. Direct measurement of hillslope erosion, particularly in the remote settings where wildfires occur, is time consuming and costly. Rainfall simulation, sediment fences and paired catchment studies have been adapted for measuring post-fire erosion in the mountainous forest regions of the western USA. The use of paired catchments to measure hillslope erosion and evaluate treatment effectiveness is illustrated by an ongoing experiment of six contour-felled log erosion barrier research sites. Deciding which type of treatments to use, as well as the locations and timing of application, requires treatment cost and effectiveness to be weighed against potential damage from unmitigated erosion. To assist in this process, a web-based Erosion Risk Management Tool has been developed that incorporates variability in rainfall, burn severity and soil properties, as well as treatment options to provide probabilistic erosion estimates for 4 years after a fire.