GIS Based Hec-HMS and Hec-Ras Modeling : A study of Woldiya watershed in Ethiopia

For proper estimation of the quantity of surface runoff generated in a watershed, understanding of the complex relationships between rainfall and runoff processes is necessary.GIS based model systems are increasingly becoming popular tools due to its capability to handle the spatial variation of hydrological and physiographic inputs of the watershed. This book focused on application of a GIS based semi-distributed watershed model (HEC-HMS) in the Woldiya watershed in Ethiopia to establish rainfall-runoff modelling for the determination of important hydrologic design parameters (peak discharge and runoff volume/runoff hydrographs). In addition to this, surface water profile of one of the channels where overtopping is computed using the HEC-RAS Hydraulic Model by employing the flood discharges calculated from HEC-HMS model in order to recommend mitigation measures for flood risk areas. This comprehensive field study should be especially useful to the Hydrologist, civil engineers, agriculturists, students, field engineers and related governmental as well as non-governmental organisations.