Real-time coastal flood hazard assessment using DEM-based hydrogeomorphic classifiers

Abstract. In the last decade, DEM-based classifiers based on height above nearest drainage (HAND) have been widely used for rapid flood hazard assessment, demonstrating satisfactory performance inland floods. The main limitation is high sensitivity of HAND to topography, which degrades accuracy these methods in flat coastal regions. addition, are mostly a given return period and generate static maps past events. To cope with two limitations, here we modify HAND, propose composite hydrogeomorphic index, develop threshold operative curves real-time assessment areas. We select Savannah River delta as test bed, calibrate proposed index Hurricane Matthew, validate developed Irma. multiplication normalized geomorphic features, distance drainage. calibration procedure tests different combinations weights features determines most appropriate mapping. Reference generated by well-calibrated hydrodynamic model, Delft3D FM water level periods. For each specific period, that provides maximum fit relevant reference map determined. collection thresholds periods curves. Validation results demonstrate total cells misclassified (summation overprediction underprediction) less than 20 % area. validation indicates efficiency our methodology fast reliable estimation areas an upcoming event, can be beneficial emergency responders risk managers.