Identification of Optimal Stream Flow Estimation Techniques In Myagdi River Basin

Abstract

The Myagdi River basin is vital component for the region’s ecological and socioeconomics systems making an in depth understanding of its hydrological behavior essential. This study applies the hydrological engineering center’s hydrologic modeling systems (HEC-HMS) to simulate and analysis stream flow within the basin with the broader goal of the strengthening water resource management and improving flood risk mitigating strategies. Comprehensive data collection and rigorous model calibration were carried out to ensure reliable outputs. The model demonstrated excellent performance with Nash-Sutcliffe Efficiency (NSE) values of 0.9829 during calibration and 0.9869 during validation, indicating a strong agreement between simulated and observed flow. HEC-HMS effectively replicated flood peaks, estimating a maximum discharge of 210.5m3/s closely aligning with the observed 205.7m3/s. The simulation produced an average monthly discharge of 79.95 m³/s, confirming the model's robustness and suitability for hydrological assessment. To complement the flow analysis, the Gumbel distribution method was employed for flood frequency estimation. This approach provided crucial insights into flood magnitudes associated with 10, 25, 50 and 100 years return periods, highlights significant potential risk within the basin. These findings reinforce the value of the model in guiding flood preparedness and infrastructure planning. The study contributes important knowledge on the basin’s hydrological and demonstrates the capability of HEC-HMS as an effective tool for future evaluations. Key recommendation includes integrating climate change projections, improving the density and quality of hydrological data, and promoting stakeholder collaboration to enhance sustainable watershed management. Implementing these strategies will bolster the basin’s resilience to hydrological extremes and support long term regional development.