Modeling Post-Wildfire Rainfall Events in the Santa Cruz Creek Watershed using HEC-HMS and GSSHA

The 2007 Zaca Fire burned about 240,000 acres of land north of Lake Cachuma, which supplies water to Santa Barbara, CA. USGS Streamgage 11124500 was able to record pre and post-fire stream discharge for the affected Santa Cruz Creek Watershed, of which 67% was burned. 80% of this burn was severe, which raises concern for extreme flood events following the wildfire. It has been observed that the extreme temperatures in wildfires not only damage vegetation but soils as well -- wildfires much more so than comparatively mild prescribed burns. Our research proposes analyzing precipitation and stream discharge data from the affected Santa Cruz Creek Watershed to quantify the effects of such widespread and severe wildfire. This study uses the Hydrologic Modeling System (HEC-HMS) from the Army Corps of Engineers (ACE) to perform event-based, lumped modeling. It also uses Gridded Surface Subsurface Hydrologic Analysis (GSSHA) to perform physics-based modeling of the same watershed. Doing so should deepen our understanding of the effects of increasingly common and severe wildfires on watershed characteristics like infiltration and streamflow.