Application of new HEC-RAS version 5 for 1D hydrodynamic flood modeling with special reference through geospatial techniques: a case of River Purna at Navsari, Gujarat, India

Abstract

Floods are among the extreme natural events which result in catastrophic damage to properties and adversely effects communities. To curb and manage the effects of such events, the decision-makers and disaster management authorities require dependable data in terms of flood depth, discharge, magnitude, and special datasets. The low lying areas of Navsari city was inundated in the floods of 2002 and 2003. This study aims to use the latest version of HEC-RAS for 1D hydrodynamic flood modelling of Purna river in Navasari city, Gujarat, India, with special reference to geospatial techniques. This study is aimed to demonstrate the geospatial analyzing capabilities of HEC-RAS v5. For the purpose of flood modeling, the river data such as bank lines, flow path lines, cross-section cut lines are extracted from Cartosat-1 DEM (Digital Elevation Model). Steady flow analysis is carried out for the simulation of a 1D hydrodynamic model. The outcome obtained from the model is in the form of water depth, which can be observed in the geospatial HEC-RAS mapper window. The flood depth maps for the 2002 and 2004 flood events are generated, which indicate that the low lying areas of Navsari city near Jalalpore and Viraval are susceptible to flooding when the discharge in the river exceeds 8836 m3/s. The accuracy of the model is calculated by comparing the simulated data with the observed data for the above-mentioned flood events. The results obtained from the 1D models are promising and accurate.