Investigation the Effects of High Resolution Digital Elevation Model (DEM) In Flood Modelling

The extreme weather condition and unplanned housing developed by people in the lower lands of the wadi streams have contributed in the occurrence of such flash floods. Flash floods cause much damage such as the landslides and mudflows, bridge collapses, damage to buildings and businesses, psychological harm to people that can reach to death. Because small topographic features affect floodplain storage and flow velocity, a hydrodynamic model setup of these regions imposes more stringent requirements on the input Digital Elevation Model (DEM) compared to upland regions with comparatively high slopes. This study presents an approach is aiming to simulate the effect of high resolution DEM in flood depth and flood extent. The main objective of this research is to analyze the effect of high resolution digital elevation model (DEM) in flood inundation modeling. The results show that, increasing of the grid cell sizes from 30m to 10m has influenced the maximum modeled flood depth to decrease from7.33 m to 6.61m, whereas the average of flood depth increased from 1.62m to 1.83m. The highest of peak discharge and runoff volume were obtained when the condition is wet. The flood simulation results showed that the higher resolution DEM has increased the average flood depth due to the fact that buildings act as barriers to the flow and water accumulates leading to increase in the water depth. Also, a decrease of a flood extension area is obtained due to the area that is occupied by the buildings.