Determination of peak flood discharge and flood prone areas using HEC HMS and HEC RAS

A flood is defined as any moderately highwater flow which overtops the artificial or natural banks. It is one of world’s most destructive natural disaster. During extreme rainfall events; flood water flow from all valleys towards the city, causing serious damage to public and private properties. In such situations; we have to identify the areas which with high risk of flooding. This study aims to analyze the peak discharge in Killi river basin based on 2,5, 10- year return periods and used for the identification of flood prone areas and to adopt appropriate plans to control and reduce the effect of floods. For this both hydrologic and hydraulic modelling are conducted using HEC HMS and HEC RAS. Peak flood discharge is estimated using HEC HMS and flow depth, velocity, water surface level is also determined by using HEC RAS. Depth of water, velocity distribution and water surface height obtained after 2D flow simulation are utilized to decide the degree of flooding. RAS-mapper is an effective tool in HEC-RAS, which can be utilized for inundation of research area. For unsteady flow analysis, each time step was done based on inflow hydrograph using RAS mapper tool in HEC-RAS, which gives the spatial distribution of the river flow. The model performance evaluation of HEC HMS was carried out by using co efficient of determination R 2 AND NRMSE. The outcomes from this study can be utilized for disaster management, flood management, early warning system by authorities in addition to infrastructure growth decisions.