Impacts of Land-Cover on Hydrology: Adjusting the Saturated Hydraulic Conductivity in a Physically-Based Model by Integrating Land Cover into Soil Data

This study introduced a new method that unites a hydrologic model using physical infiltration mechanisms with a combination of a hydrologic soil group (soil) and a land use and treatment class (cover) to integrate LULC data into soil data. The new method has been incorporated into the WEHY model to simulate hydrologic conditions over the Cache Creek Watershed (CCW) and Shasta Dam Watershed (SDW) in Northern California. For testing the effects of integrating LULC and soil data on WEHY simulations, this study used four different soil datasets. The first soil dataset (S1) was obtained from the local soil database including SSURGO and STATSGO2. The third soil dataset (S3) is the global soil data SoilGrids-1km obtained from World Soil Information. While the second (S2) and fourth (S4) soil datasets were calculated from the new methodology that integrate the local LULC into the local soil and global soil respectively. With the WEHY model for SDW and CCW validated by historical hydro-climate data and the four different soil datasets, it was possible to demonstrate the effects of different soil datasets on the performance of the WEHY model. The results of this study suggest that this approach is able to provide a fine soil dataset and then improve the performance of WEHY model over the target watersheds. In addition, this approach can then be used for the estimation of the impact of changes in LULC on hydrologic response under future climate change conditions.