Investigating the Application of Remote-Sensing Based DEMs in Hydraulic Simulation of Flood

Digital elevation models (DEMs) are one the most important inputs of hydraulic and hydrological models. Due to lack of ground high resolution maps, especially in data sparse regions, hydraulic modeling is a daunting and more challenging task. In recent years, remote-sensing based DEMs due to ease of access and being free of charge are extensively used in several studies particularly hydraulic modeling. One of the most important questions on application of hydraulic models is the efficiency of these DEMs in flood simulation. On this basis, this research focused on application of remote-sensing based DEMs on the performance of HEC-RAS-1D model in two different rivers. The results show that the accuracy of ALOS-30m DEMs in deriving geometric model and subsequently flood simulation is higher and considerable than other DEM sources. For example, the average relative error (RE) of using this dataset in simulating inundated extents in Sarbaz and SojasRood rivers is lower than 13 and 9 %, respectively. In contrast, the results of ASTER-30m DEMs in both rivers is not satisfactory and the average RE of inundated extents is more than 38%. As an overall conclusion, one can deduce that ALOS and ASTER DEMs are the best and the worst datasets for creating geometric model and flood simulation. Hence, in data sparse areas or underfunding projects, using ALOS-30m DEMs especially in early Designs can be useful and beneficial.