UAV-Based High-Resolution DEM Application for River Cross-Section Derivation and 1D Flood Assessment

The precise digital elevation model (DEM) is the need of an hour for flood risk assessment to reduce the loss of lives and properties. The benchmarked free source nationally available DEM is Cartosat and globally available DEM is SRTM, which is widely used for hydrodynamic modeling by developing countries. However, it covers the course resolution. High-resolution DEM is required to execute the hydrodynamic model in 1D and 2D and to improve the flood decision-making system at the sub-metric level for urban flood mapping and assessment. Therefore, to reduce the data deficiency for flood decision-making systems in urban areas in developing countries, high-resolution DEMs are generated. This attempt has been performed over the Sabarmati River with a stretch of 5 km, covering the 8 km2 of the area and its surrounding. The advanced survey was done using a UAV named 4RTK (Real-Time Kinematic) Phantom for the study area. The data collected were processed with the help of Pix4D. This UAV is then converted into different grids size of 0.5 m × 0.5 m to 10 m × 10 m resolution to perform the simulation for the study area using Global Mapper. These DEMs are used as input parameters for performing any hydrodynamic simulation. The high-resolution DEMs can be utilized for the preparation of river geometry extraction and comparisons of the river bed and river banks. This high-resolution DEM is used in the hydrodynamic model to produce flood inundation, velocity, depth, and water surface elevation maps. The research shows that high-resolution DEM is most applicable to creating a high-resolution map for flood decision-making. Hence, high-resolution DEMs influence the accuracy of flood forecasts, so even the most severe catastrophes can be mitigated.