DESIGN FLOOD ESTIMATION FOR SUKTA DAM USING ALTERNATIVE APPROACHES AND DAM BREAK ANALYSIS

Abstract

Assessing drainage morphometric parameters is key to gaining insights into a region's hydrological and morphological features. This study aims to understand the Sukta Dam catchment area by analysing its drainage basin morphometric parameters. Remote sensing and GIS were employed as effective means of delimiting and comprehending drainage basin morphometry. The measurement of drainage morphometric parameters was conducted using SRTM DEM (30 m) in ARC GIS 10.8. Also, the HEC-Geo HMS model incorporated in ARC GIS was used to calculate catchment characteristics. Further using the above physiographic parameters in conjugation with the Flood Estimation Reports and PMP Atlas of the Narmada Basin, a Unit Hydrograph and a Flood Hydrograph were developed, and a Probable Maximum Flood was obtained by using a hydrometeorological approach as carried out by Central Water Commission (CWC) for various other Dams. Also, various alternate approaches like the Dickens formula, Ryves formula, Inglis formula, envelope curves, and regional formula developed for the particular subzone were used to calculate the design flood. In the absence of rainfall ordinates, the HEC-HMS model flood peak discharge was analysed using a hypothetical storm depth after analysing the curve number for the catchment by developing the soil map and LULC map for the catchment and using the TR55 report. These calculations helped us to see if the spillway capacity was sufficient to accommodate the calculated Probable Maximum Flood (PMF). It was found that spillway capacity was insufficient to accommodate the calculated design flood. The inflow flood hydrograph obtained was used as an upstream condition to carry out Dam break analysis for overtopping and piping conditions using the HEC-RAS model. It was found that overtopping failure has more failure depth downstream than the piping failure. Also, flood inundation mapping was done to determine which villages are vulnerable in case of any future failure of the aDam.