Performance Assessment of DEM Vertical Sensitivity on Two-Dimensional Hydrodynamic Simulation in an Alluvial Tributary Floodplain of the Brahmaputra Lower Basin in India

The application of geospatial and hydraulic approaches for understanding the genesis of downstream flooding are standard practices around the globe. Digital elevation models (DEM) are widely used in hydrodynamic simulations and provide the flooding extent information, magnitude, and distribution of the flow parameters in the main channel as well as in floodplains. However, the precision and accuracy of these DEMs are major concerns during their usage in the hydrodynamic simulations. In this work, a comparative assessment is carried out between the CARTOSAT DEM and Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) DEM with the observed elevation data and then incorporated into a two-dimensional hydrodynamic model. The two-dimensional geometry and radiometry are analyzed using ERDAS Imagine software. Results indicate that CARTOSAT-I DEM shows an R-2 of 0.66 with the ground data, and an R-2 of 0.281 is found with ASTER DEM. However, from the standpoint of two-dimensional hydrodynamic simulations, Nash-Sutcliffe efficiency (NSE) of 0.86 is found for simulations with CARTOSAT-I DEM, and 0.65 is found for ASTER DEM.