The availability and distribution of water varies nationally and regionally. The availability of fresh water is stressed due to growing population coupled with sustainable developmental efforts, the uneven distribution of water resources over time & space, their modification through human use & abuse and many others. The study area is WFR-KSM basin which lies between 67°52’ to 75°19’ E longitudes and 20°53’ to 26°57’ N latitudes, covering areas in Rajasthan, Gujarat and whole of Diu. Hydrologically, it is divided into six sub basins and 268 watersheds (India-WRIS). The annual and monsoon season water availability in the basin, its sub basins and watersheds for water year 2013-14 was calculated by SCS curve number method using IMD 0.25 degree rainfall, NRSC NR Census LULC, NBSS & LUP soil data and MODIS evapotranspiration data. The water availability in the basin was estimated to be 34.67 BCM annually and 47.4 BCM in monsoon season ranging from 0 to 505 MCM annually and from 0 to 647.23 MCM in monsoon season in the watersheds of the basin. The spatial interpretation of water availability in watersheds indicated more water availability in the southern part of the basin and less water availability in the watersheds lying in northern part of the basin.