Characterization of hydrology and sediment transport following drought and wildfire in Cache Creek, California

Introduction A hydrologic model has been developed to assess wildfire effects on hydrology and sediment transport in the Cache Creek watershed of northern California (Figure 1). The worst drought in California in over 1,200 years occurred between 2012-2017 (Griffin, 2014), depleting surface water and groundwater supply and drying out the soils past wilting point. In the summer of 2015, the Jerusalem and Rocky fires burned roughly 40,000 acres within the Cache Creek watershed below Clear Lake (Figure 1). The fires varied in intensity across the watershed, resulting in spatially variable changes of soil properties and vegetation cover, with unknown changes in hydrology and sediment transport in the area. Post-fire effects on hydrology and sediment transport can be challenging to model, however numerous studies in other watersheds have shown increased runoff and erosion and reduced saturated hydraulic conductivity of soils, especially in the high burn severity class (DeBano, 1966; DeBano and Krammes, 1966; Robichaud, 2000a, 2000b; Johansen et al., 2001; Pierson et al., 2001, 2002).