Topic: DEM Generation and Flood Hazard Assessment by a Geomorphological approach
Presenter : Venkatesh Raghavan
In this study, a relatively flat area in the south of Danang city was targeted to generate high resolution digital elevation model (DEM). This area is under high risk of flood hazard every year. An algorithm, namely BS-Horizon using Fortran program (Nonogaki et al., 2012) was used to create DEM for this flat area. BS_Horizon was evaluated as one of the highest accuracy method for generating DEM with the bi-cubic B-spline algorithm. This algorithm enables using elevation data as equality-inequality constraints on the surface. The optimal surface is the smoothest one that satisfied the given constraints (Nonogaki et al., 2012). The contour lines and elevation points data extracted from 1:10000 topographic map were used as input data in BS-Horizon. DEM from BS-Horizon has the higher accuracy than DEMs from other methods and supports to extract reliable geomorphologic features . From this DEM, a potential flood hazard map was built based on landform classification result and land-cover map. The result was compared with past flood inundation map and flood prones map given by Danang city government to validate the flood hazard prediction map.