In steep landscapes, burning of vegetation can lead to a pulse of sediment delivery from hillslopes to channels by the process of dry ravel, facilitating destructive post-wildfire debris flows during subsequent rainstorms. However, the magnitude of post-fire dry-ravel yield is highly variable and the controls governing its occurrence remain poorly constrained. Here, we exploit extensive pre- and post-wildfire (but pre-rainfall) aerial lidar data and imagery from southern California to quantify dry-ravel loading of headwater valleys following the 2020 Bobcat, El Dorado, and Apple Fires. We combine topographic change detection, manual mapping, and field calibration to map deposits ranging from 30 cm to >3 m in thickness across 184 km^2 of varied terrain in the San Gabriel and San Bernardino Mountains. We also present three new detrital 10Be erosion rates and integrate these into a regional compilation to constrain soil production rates and hillslope recovery timescales. For a given region, dry-ravel yields at the small catchment scale (10^4–10^5 m^2) increase with mean hillslope angle up to ~40–45°, and appear to decline in steeper, rockier catchments. However, for the same slope, dry-ravel yields vary by more than 16× between different regions. Using a new metric incorporating lidar-derived, post-fire vegetation height, we account for local variations in dry-ravel yield, but large regional differences remain unexplained. Our results highlight the utility of repeat airborne lidar for quantifying post-wildfire dry-ravel accumulation in headwater valleys and demonstrate a dominant slope control on dry-ravel yield, with implications for understanding sediment dynamics in steep, burned landscapes.

The datasets in this resource contains two zip files separated into shapefiles by individual fire: (1) dry ravel mapping polygons and (2) burned watersheds for yield calculations as described in Fong et al., 2026. Each zip file contains a readme describing the field and attribute table. The projected geographic coordinate system is NAD1983 UTM Zone 11 (EPSG: 6340).

Fong, Brandon T., DiBiase Roman A., Lamb, Michael P., Minear, J. Toby, Corbett, Lee B., Bierman, Paul R. (2026). Slope and burn severity controls on post-wildfire dry-ravel loading of headwater channels in southern California, USA [submitted].