WaSSI model code, input, and output data for projecting the potential effects of climate and land use change on water balances and water supply across the conterminous United States

The linkages among forests, water, and people have long been recognized by natural resources professionals and policymakers. The purpose of this study was to provide a contemporary assessment of current and future forest and water resource issues broadly across the conterminous United States and specifically in the Southern United States as part of the Southern Forest Outlook (SFO) Water Analysis. The SFO Water Analysis was done using a combination of literature review, hydrologic modeling, and data synthesis to address pressing research questions, leveraging scenarios of future climate, land use, and forest conditions developed as part of the 2020 Resources Planning Act Assessment. This data publication includes the Water Supply Stress Index (WaSSI) model inputs, outputs, and code developed for the SFO Water Analysis but also includes input and output data for the conterminous United States. Inputs and outputs span the years from 1981 to 2070 and are based on 20 scenarios of future climate, land use, and forest conditions developed as part of the 2020 Resources Planning Act Assessment as well as historical observed climate and land use. All inputs and outputs are scaled to the Watershed Boundary Dataset (WBD) 12-digit Hydrologic Unit Code (HUC12) subwatershed scale. The WaSSI model uses inputs of soil information, land use, vegetation leaf area index (LAI), and climate data to predict the monthly watershed water balance and accumulated streamflow across the conterminous United States. Outputs of WaSSI include monthly potential evapotranspiration, actual evapotranspiration, snow water equivalent, water yield, and accumulated streamflow. Additionally, this package includes decadal upstream land use from 2020 to 2070 at each HUC12 outlet for all RPA scenarios.The objective of this analysis was to integrate future projections of climate and land use change, and investigate potential effects on water resources in the South between 1981 and 2070.For more information about this study and these data, see Caldwell et al. (2024).