Hydrodynamic modelling approach for scientific assessment of flood-prone areas at basin scale

Scientific assessment of flood-prone areas under different return periods is very vital input in designing any hydraulic structures and in flood disaster risk reduction. Satellite based flood maps provides information on flood extent in any area as per its date of satellite pass and its extent only. Computing spatial flood depth and velocity at different return periods using very high resolution digital terrain models is important parameters in flood risk assessment. This study addresses scientific assessment of flood prone areas and risk assessment using hydrodynamic modelling approach in the Godavari Basin, India. Considering the drainage pattern, the floodplains of the basin is divided into 5 stretches. 30 years daily historic discharge data of all these stretches at both upstream and downstream are analysed. Considering the statistical distribution pattern of historic discharge data, Log-Pearson Type III method was used in computing flood magnitudes of different return periods for each stretch. Very high resolution Digital Terrain Model is used in flood inundation simulation for different return period floods under unsteady flow conditions. Manning’s roughness parameters are extracted using satellite based land use grids. Spatial variation of flood depths and velocities are analysed and risk at different return periods are computed.