RUNOFF SIMULATION IN THE UPPER INDUS BASIN USING HEC-HMS AND GIS-BASED MODELING TECHNIQUES

Abstract Water, a vital resource for life and agriculture, faces escalating global scarcity, especially in developing countries where irrigation consumes most freshwater, highlighting the urgent need for better planning and management despite limited hydrological data. The Hydrologic Modeling System (HEC-HMS) was applied to simulate runoff in the Gilgit River Basin, a key tributary of the Upper Indus Basin. The model integrates meteorological and spatial datasets from 1984 to 1998 to perform continuous runoff simulation. Using ArcGIS and the HEC-Geo HMS extension, the watershed was delineated, sub-basins identified, and key hydrological parameters were derived. Model calibration was conducted using observed streamflow data for the year 1984 and extended to a 10-year period, followed by validation for the years 1995 to 1998. The model showed satisfactory performance with RMSE, SSR, and PWRMSE errors of 8.5%, 9.6%, and 3.4% respectively. The results indicate the suitability of HEC-HMS for hydrological simulation and runoff forecasting in the Upper Indus Basin and highlight its potential for sustainable water resource planning in the region.