Application and verification of the WEPPcloud sediment and ash source and transport model, 2022 Pipeline Fire, Schultz Creek, Arizona, USA

Background Post-wildfire floods are being studied more frequently due to their increased impacts at the wildland–urban interface (WUI). The 2022 Pipeline Fire burned 25% of the Schultz Creek watershed in Arizona, USA, and rainstorms over the burn scar triggered four flash flood events in 2022 and a flood event during the spring-time thaw in 2023. Aims The purpose of this study was to apply and validate the online WEPPcloud model using post-event observations. Methods Modeling was completed using the WEPPcloud platform, field verification included bathymetric surveys of a downstream pond and repeat drone surveys of a separate flood control basin. Field observations were compared with spatial erosion model predictions. Key results Total observed sediment delivery to areas downstream of the WUI was 2190 Mg in 2022 and 1122 Mg in 2023. The WEPPcloud model predicted 216 Mg year−1 of mineral sediment transport and up to 1900 Mg of fine sediment/ash in a routine 10-year rain event (immediately post-wildfire). Conclusions The model provided a reasonable approximation of sediment delivery from events but more work is needed on spatial predictions. Implications Continued case studies may improve the precision and accuracy of WEPPcloud allowing for greater use by the research and applied management community.