Analyzing the Impact of Ungauged Hill Torrents on the Riverine Floods of the River Indus: A Case Study of Koh E Suleiman Mountains in the DG Khan and Rajanpur Districts of Pakistan

Floods are one of the most destructive natural hazards in Pakistan, causing significant damage. During monsoons, when westerly winds and concentrated rainfall occur rivers’ catchments, floods become unmanageable. Given limited resources there has been minimal effort to quantify amount runoff generated by ungauged catchments. In this study, ten hill torrents Koh e Suleiman (District Rajanpur DG Khan), an area affected flash flooding 2022 due extreme precipitation events, were investigated. The Hydrologic Engineering Centre’s Modeling System (HEC-HMS), a semi-distributed event-based hydrological model, was used delineate streams runoff. Statistical analysis trends performed using non-parametric Gumbel value type I distribution, Mann–Kendall test, Sen’s slope. results study show that total inflow river Indus is 0.5, 0.6, 0.7, 0.8 MAF for 25, 50, 100, 200 years return period rainfall, respectively. This presents appropriate storage options with retention potential 0.14, 1.14, 1.13 based on hydrology these enhance spate irrigation as flood control future.