Water budget estimation and surface water supply and use (SUI) trends for a water availability assessment across the conterminous United States for water years 2000–2020

This pipeline calculates a simple monthly water budget that includes water supply and consumptive use for irrigation, and public supply for 12-digit Hydrologic Unit Code (HUC12) subwatersheds across the conterminous United States for water years 2000-2020. Water budget results also include an assessment of supply and use imbalances within the context of historical climatic conditions to calculate a surface water supply and use index and when considering a range of environmental flow allocation methods. This pipeline ingests (1) water supply, consumptive use, and routing information; (2) accumulates and routes the water balance through the HUC12 network; (3) calculates the surface water supply and use imbalance (SUI); (4) and calculates SUI trends. This pipeline was developed in support of the USGS National Water Availability Report, trends chapter (Miller et al., in review).
Monthly HUC12-level water supply estimates are derived from two national-scale hydrologic models: the USGS National Hydrologic Model (NHM), which is a national-scale application of the Precipitation Runoff Modeling System (Regan and others, 2018), and the Weather Research and Forecasting Hydrologic Model (WRF-Hydro; Rafieeinasab and others, 2024). Both hydrologic models were forced with the CONUS404 hydroclimate dataset (Rasmussen and others, 2023). Monthly HUC12-level consumptive water use was estimated from three national-scale irrigation, thermoelectric power generation, and public supply water use models (Alzraiee and others, 2024; Harris and others, 2025; Martin and others, 2023). The pipeline has four primary phases: (1) fetch water supply and consumptive use data, (2) process those data into a common format for routing and accumulation through the HUC12 network, (3) calculate and route the water budget through the HUC12 network and calculate SUI values; and (4) calculate trends in SUI. In the third step, the water budget is calculated using both the NHM and WRF-Hydro separately, and those monthly results are averaged for each HUC12. See Gorski et al. (2025) and Miller et al. (in review) for more information on the methods.