GSFLOW model to extend the San Antonio Creek Integrated Model and simulate future water availability scenarios, San Antonio Creek Valley watershed, Santa Barbara County, California

In the San Antonio Creek Valley Watershed (SACVW) of Santa Barbara County, California, climatic conditions, surface-water diversions, and groundwater withdrawals potentially affect water availability, magnitude of streamflow in San Antonio Creek, and the extent and quality of protected species habitat in the Barka Slough wetland. Future climate in central California may have warmer and drier conditions and more variable precipitation (Flint and Flint, 2012). This may result in an increase in overall water demand from agricultural, military, and municipal entities in the SACVW. In cooperation with the Santa Barbara County Water Agency, the U.S. Geological Survey has developed a suite of future models that represent the SACVW hydrologic system. The previously published integrated hydrologic model of the SACVW (simulating water years 1948–2018; Woolfenden and others, 2022) was extended to include water years 2019–21, and then modified to simulate two versions for future years 2022–51. Two models simulating future years 2022–51 were constructed, each with different climate inputs: 1) a repeated historical climate (SACIMF.1), and 2) a warmer and wetter climate model-based input (SACIMF.2). SACIMF.1 repeats the climate input from 1990–2021 in reverse order to represent the future years, while SACIMF.2 model utilizes the 2070-centered Drier Extreme Warming climate change projection (2070 DEW; California Department of Water Resources, 2020). The model with 2070 DEW climate has warmer temperatures and an increase in average annual precipitation, driven by more frequent large precipitation events, relative to the historical climate. This data release includes these two future models referred to as the San Antonio Creek Integrated models - future 1 and 2 (SACIMF.1 and SACIMF.2). The SACIMF.1 and SACIMF.2 were developed as a tool to simulate the potential long-term effects of changing climatic conditions on 1) water availability, streamflow, groundwater flow, groundwater recharge and other hydrologic conditions throughout the SACVW, 2) groundwater discharge to San Antonio Creek in Barka Slough, and 3) streamflow, stream disconnection, and depth to groundwater as key habitat metrics for protected species in Barka Slough.