Assessing Hydropower Potential in Nepal’s Babai River Basin: An Integrated GIS and SWAT Hydrological Modeling Approach

Abstract

Nepal has great potential for hydropower development because of its steep landscape, many rivers, and favorable climate. This study examines the run-of-river (RoR) hydropower potential of the Babai River Basin using a combined approach of Geographic Information System (GIS) tools and the Soil and Water Assessment Tool (SWAT) model. The basin was divided into sub-basins using a 30 m resolution Digital Elevation Model (DEM), and important data such as soil, land use/land cover, slope, and weather records were used in the analysis. The SWAT model was calibrated for the period 1990–2000 and validated for 2000–2006 using the SUFI-2 method in SWAT-CUP, and its performance was evaluated using R², Nash–Sutcliffe Efficiency (NSE), and Percent Bias (PBIAS). The results showed a satisfactory range for the calibration and validation processes. Hydropower potential was estimated using simulated river discharge and available head at different flow levels, and the total potential of the basin was found to be about 80.3 MW at Q₄₀. Two technically suitable sites were also identified, with estimated capacities of around 8.3 MW and 4.8 MW. Overall, the study shows that the Babai River Basin has good potential for small- to medium-scale hydropower development and provides a practical method for hydropower planning in regions with limited data.