Between 1998 and 2002, six sites were established immediately after large wildfires in the western United States to determine the effectiveness of contour-felled log erosion barriers in mitigating post-wildfire runoff and erosion. In each pair of matched, burned, and small watersheds (1–13 ha), one was treated with contour-felled log erosion barriers and one was left untreated as a control. For 4 to 6 post-fire years, runoff and sediment yields were measured and correlated with rain properties. High-intensity rainfall produced most of the measured runoff and sediment yields except in the southern California site, where long-duration rain events produced most of the runoff and erosion. For small rain events (less than the 2-year return period for the 10-min duration), the runoff, peak flows, and sediment yields were lower in the treated watersheds than in the control watersheds, but there was no treatment effect for rain events with larger return periods. Improper installation and degradation over time reduced the effectiveness of contour-felled log erosion barriers. Rainfall characteristics and installation procedures should be carefully considered before choosing contour-felled log erosion barriers for post-fire hillslope stabilisation.

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.

Post‐wildfire changes to hydrologic and geomorphic systems can lead to widespread sediment redistribution. Understanding how sediment moves through a watershed is crucial for assessing hazards, developing debris flow inundation models, engineering sediment retention solutions, and quantifying the role that disturbances play in landscape evolution. In this study, we used terrestrial and airborne lidar to measure sediment redistribution in the 2016 Fish Fire, in the San Gabriel Mountains in southern California, USA. The lidar areas are in two adjacent watersheds, at spatial scales of 900 m² to 4 km², respectively. Terrestrial lidar data were acquired prior to rainfall, and two subsequent surveys show erosional change after rainstorms. Two airborne lidar flights occurred (1) 7 months before, and (2) 14 months after the fire ignition, capturing the erosional effects after rainfall. We found hillslope erosion dominated the overall sediment budget in the first rainy season after wildfire. Only 7% of the total erosion came from the active channel bed and channel banks, and the remaining 93% of eroded sediment was derived from hillslopes. Within the channelized portion of the watershed erosion/deposition could be generally described with topographic metrics used in a stream power equation. Observed sediment volumes were compared with four empirical models and one process‐based model. We found that the best predictions of sediment volume were obtained from an empirical model developed in the same physiographic region. Moreover, this study showed that post‐wildfire erosion rates in the San Gabriel Mountains attain the same magnitude as millennial time scale bedrock erosion rates.