This shapefile represents the spatial distribution of mean annual water-budget components, in inches, for Kauaʻi, Hawaiʻi for a 2020 land-cover and a set of four climate scenarios. The four climate scenarios used in the water-budget analyses include a reference climate scenario representative of recent conditions during 1978–2007, hereinafter the 1978–2007 scenario, and three downscaled future-climate projections. The three future-climate projections include (1) a mid-century scenario using projected rainfall conditions representative of phase 5 of the Coupled Model Intercomparison Project (CMIP5) Representative Concentration Pathway 8.5 (RCP8.5) 2041–71 scenario climate described in Elison Timm and others (2015), hereinafter the SD RCP8.5 2041–71 scenario, (2) a dry-climate scenario using projected rainfall conditions representative of the CMIP5 RCP8.5 2071–99 scenario climate described in Elison Timm and others (2015), hereinafter the SD RCP8.5 2071–99 scenario, and (3) a wet-climate scenario using a dynamical downscaling approach by configuring a regional climate model for the western North Pacific and southwest Pacific region, including the Hawaiian Islands described in Zhang and Wang (2017), hereinafter the Hawaiʻi Regional Climate Model version 2 (HRCM2) RCP4.5 2080-99. The water-budget components for each model subarea were computed for each climate scenario using a water-budget model developed by Oki (2022). A set of land-cover classes representative of conditions around 2020 was developed for this study to define the land-cover conditions for each model subarea (or polygon). The shapefile attribute information associated with each subarea present the land-cover class and an estimate of mean annual rainfall, fog interception, irrigation, septic-system leachate, seepage from reservoirs and cesspools, runoff, canopy evaporation, total evapotranspiration, and groundwater recharge. This shapefile also includes select geographic and land-cover attributes of the model subareas. Brief descriptions of the water-budget components and attributes are included in this metadata file. Refer to Kāne and others (2024) for further details of the methods and sources used to determine these components and attributes.