Application of HEC-RAS Flood Modeling of a Himalayan Foothills River: A Case Study of a Part of the River Torsa

Floods in the Himalayan river are a concerning natural event, especially in the foothill zone. The Torsa River is a prominent river of eastern Himalaya, known for being highly prone to seasonal flooding due to intense monsoonal precipitation and complex topographic conditions. This work is purposed to quantify the flood inundation and risk perception of the Torsa River in the foothill area near the Cooch Behar town. HEC-RAS 1D flood inundation method is applied on high-resolution terrain data (Digital Elevation Model) and historical unsteady flow data, to simulate the flood dynamics and delineate the inundation zone along the Torsa River. This application is very important for understanding flood-prone areas, land-use planning, and risk zonation.