ASSESSING STREAMFLOW DYNAMICS IN THE CHO CHU RIVER BASIN USING SWAT MODEL

Abstract

This study simulates and evaluates streamflow dynamics in the Cho Chu River Basin (a tributary of the Cau River) during the period 1990–2020 using the Soil and Water Assessment Tool (SWAT) within a Geographic Information System (GIS) framework. Input datasets include a Digital Elevation Model (DEM), land use/cover, soil types, and long-term meteorological records. These datasets were standardized and processed within a GIS environment to ensure spatial and temporal consistency for hydrological modeling. The spatial configuration of the watershed was divided into 26 sub-basins and 273 Hydrological Response Units (HRU), representing characteristic combinations of topography, land use, and soil characteristics. The model demonstrated robust performance, with an R² = 0.803 between observed rainfall and simulated streamflow, confirming the model’s reliability in mountainous terrain. The results revealed pronounced seasonal variation, with surface runoff concentrated from May to October, peaking at 347.32 mm in July 2001, while dry-season runoff approached zero. Spatially, surface runoff varied significantly among sub-basins, ranging from 23.49 mm to 52.74 mm, highlighting the influence of local topography, vegetation cover, and rainfall distribution. These findings provide a scientific basis for watershed-scale water resource management, land use planing, erosion control, and sustainable development, especially in the context of increasing climate variability.