Arizona Base-flow Index (HUC-8)

This dataset provides long-term estimates of the Base-Flow Index (BFI) for all HUC-8 basins in Arizona from 1980 to 2020. BFI, representing the groundwater-derived portion of streamflow, was computed at gauged sites using recursive digital filtering and then regionalized to ungauged basins through an XGBoost regression framework. Climatic and topographic variables served as primary predictors to capture spatial controls on base-flow generation across Arizona’s diverse hydroclimatic gradients. The resulting product offers consistent, basin-scale BFI estimates suitable for hydrologic assessment, groundwater–surface water interaction studies, and evaluation of streamflow-associated recharge in data-limited regions.