Study of Impact of Different Levels of Water on Backwater Effect of Sardar Sarovar Dam up to Maheshwar Dam using HEC-RAS Model

Abstract

In this study simulated scenario to evaluate the backwater impacts of an inline structure has been evaluated for River Narmada. The inline structure is the Sardar Sarovar dam and its effect has been seen up to the toe of Maheshwar Dam site about 210 km upstream. To determine the magnitude of the of the back water effects was carried out using HEC-RAS model software. 1D unsteady flow modeling in HEC-RAS is employed. To establish the geometries as well as the precise land map information a DEM with a resolution of 30mx30m was used. In order to conduct the unsteady flow analysis, the data from the observed flow hydrograph was used. The WSE parameter was calculated at various locations upstream considering no inline structure ensuring free flow, inline structure with three initial water levels that is the crest level of ogee spillway, the full reservoir level and the maximum water level of the Sardar Sarovar Dam. Historical flood event from the 29th of August to the 4the of September in the year 2019 was taken as hydrologic data. The results of the model application reveal that the impact of backwater effect is prolonged in the river channel and affects the flooding of the stretch. The outcomes of this study can be used for flood control and flood prevention warning.