Rainfall-runoff simulations in ungauged Fusre River basin, Nepal using HEC-HMS model

Water resources assessment and management in ungauged basins are highly challenging but important task. It requires accurate simulation and estimation of streamflow characteristics. This study focuses on the simulation of rainfall-runoff processes in an ungauged Fusre River basin, a tributary of Seti River basin, Nepal using a semi-distributed hydrological model: Hydrologic Engineering Center-Hydrological Modeling System (HEC-HMS). The HEC-HMS model setup consists of a basin model, meteorological model, control specifications, and time series data. HEC-GeoHMS, an ArcGIS extension, enabled to prepare basin model parameters of the Seti river basin. Using daily streamflow data of Damauli hydrological station and precipitation data of 3 meteorological stations over the Seti basin, calibration and validation of the HEC-HMS model parameters were carried for 2007–2014 and 2015–2019 periods, respectively. Both continuous and event-based rainfall-runoff modeling were carried out to produce mean monthly and peak discharge values. Model performance was evaluated using values of NSE, RMSE, PBIAS, and R2 statistical parameters. After suitable values of these statistical parameters, the HEC-HMS model was applied for producing streamflow values in ungauged Fusre River basin. Flood-frequency analysis of simulated streamflow values projected a peak discharge of 457.3 m3/s and 534.6 m3/s for the 10- and 20-year return periods, respectively.