Fluvial sediment samples were collected from the lowermost reaches of 21 coastal watersheds in California, in order to characterize surficial grain size of river sediment from deposits that appeared to be recent based on field context. Samples were collected using a trowel to sample the uppermost 10 cm of sediment. Sampled locations included river-deposited sediment, upstream of tidal influence. Samples excluded coarse gravel and cobble grain sizes, if present. The watersheds selected for sampling have ...

This table contains measured and modeled postfire debris flow volumes alongside the associated sources for debris flow documentation, locations, and volumes. We conducted a search of scientific literature and news media reports to find documentation of debris flows that may have followed all wildfires greater than 100 square kilometers that occurred between 1984 and 2021 in California. The wildfires listed are all the fires we found that had documented postfire debris flows. Some fires had field ...

This table contains geographic information defining watersheds that were burned in large wildfires (greater than 100 square kilometers) that occurred in California or California-draining regions (i.e., upper Klamath watershed) between the years 1984 and 2021. Each wildfire was broken into tens to thousands of small watersheds, and each row of this table contains geographic information defining a single watershed.

These data show model estimates of debris flow likelihood and volume that may be produced by a storm in a recently burned landscape. The scientific methods used by the U.S. Geological Survey Emergency Assessment of Post-Fire Debris-Flow Hazards were changed following 2015, and these shapefiles are a re-release of ten fires that occurred between 1997 and 2015 fires, using the updated methods. These ten fires were re-run to provide estimates of debris flow volumes as post-fire debris flows were documented but ...

This is a shapefile containing polygons of watersheds that were burned in wildfires that occurred in California between 1984 and 2021. The Water Erosion Prediction Project (WEPP) model for postfire erosion was run on all watersheds for the first year following wildfire and the results of this modeling effort are included as attributes of each watershed polygon.

These data show all the postfire erosion results affiliated with this data release summed by wildfire and attached to a polygon of each fire perimeter, as defined by Monitoring Trends in Burn Severity (MTBS). The results are shown as attributes for each polygon of wildfire perimeter. Some of the original MTBS data (name, ignition date, and ID) were preserved to allow for joining to other MTBS data. Results include WEPP modeling results of hillslope and channel erosion, a sum of postfire debris flow modeling ...