Flood Inundation Simulation of Mahanadi River, Odisha During September 2008 by Using HEC-RAS 2D Model

Abstract

Odisha state witnessed severe flooding in the years 2003, 2008, 2009 and 2011 which affected major districts like Cuttack, Khurdha, Jagatsinghpur, Puri and Kendrapada. HEC-RAS 2D is a hydraulic model which is used to simulate water flowing through rivers and open channels. In addition, the model also provides the depth of water, velocity and water surface elevation with respect to time. Using this model, part of Mahanadi River stretch from Tikarpara to Mundali was taken as the study area for simulating floods during September 2008. Inputs to the model like CARTO DEM at 10 m posting, discharge data, roughness co-efficient were provided and flood inundation was simulated. The flood extent from the model was validated with the satellite derived flood extent obtained from RADARSAT satellite. Model performance was evaluated based on the parameters F1 and F2 where, F1 and F2 are measures of fit which range from 0 to 1 and −1 to 1 respectively. If the fit value is closer to 1, it indicates that the model performance is better. Sensitivity analysis is carried out to investigate the model performance for different roughness coefficients of the flood plain. From the study, it is observed that the model performed well for roughness coefficient 0.020 and the measures of fit F1 and F2 were found to be 0.85 and 0.74 respectively. A flood hazard map was prepared based on the flood depth for the study area.