Flow duration curve analysis in Balkhab subbasin, Afghanistan using HEC-HMS and ArcGIS

Afghanistan's river basins face significant challenges in hydrological data due to prolonged conflict and degraded monitoring networks, constraining reliable water resource assessment. This study estimates streamflow and water availability in the Balkhab subbasin of the North River Basin using the HEC-HMS model integrated with ArcGIS. The modelling framework employed the Soil Moisture Accounting (SMA) loss method, temperature-index snowmelt module, Muskingum–Cunge routing and Hargreaves evapotranspiration method. Meteorological and discharge data from 2012–2016 were processed and used for model calibration (2012–2014) and validation (2015–2016). Performance evaluation using NSE and PBIAS indicated satisfactory accuracy at daily (NSE = 0.52, PBIAS = +3.2%) and monthly scales (NSE = 0.68, PBIAS = +2.8%). Derived flow duration curves revealed pronounced seasonal variability driven by snowmelt. The results demonstrate the applicability of HEC-HMS for water resources assessment in data-scarce basins.