Hydrologic System Response Models for Hilly Sub-catchments of a River: Kinematic-wave Based Geomorphologic Instantaneous Unit Hydrograph for Predicting Direct Runoff from Watersheds

The geomorphologic instantaneous unit hydrographs (GIUH) were developed to predict the direct runoff hydrograph from two hilly sub-watersheds of Ramganga catchment in Uttarakhand State of India. Based on the kinematic-wave theory, the topographic characteristics and Horton's stream-order-law ratios for the watersheds, the travel times for overland and stream-flows in a stream-ordering system of the watershed were analytically and probabilistically determined to develop the GIUH. The two-parameter Gamma-type model was also used to develop the GIUH for these watersheds. The performance of the developed models was evaluated by comparing the predicted and observed direct runoff hydrographs for the storm events occurring in the watershed. As the development of this model needs only the geomorphologic parameters of the watershed, this model could be applicable to any ungauged or partially gauged hilly watershed with reasonably good accuracy.