By
Dr. Bhabagrahi Sahoo
With the drastic decline of in-situ stream gauging networks in the recent world river basins due to its high operational and maintenance cost involvement, predictions in ungauged basins is of great importance for the scientific research community. In light of this, the geomorphological instantaneous unit hydrograh (GIUH)-based Clark and Nash models were developed and applied to the Ajay River Basin at Jamtara in the States of Bihar and Jharkhand, India; and their performances were compared with the conventional Clark IUH option of HEC-1 package and Nash IUH model using four performance criteria. The geomorphological parameters of the catchmnet under study were evaluated using the ERDAS EMAGINE 8.5 software for two map scales, viz., 1:50,000 and 1:2,50,000. The direct surface runoff hydrographs were computed with reasonable accuracy by both the GIS supported GIUH-based models. The developed GIUH models are especially useful for estimation of floods for ungauged or scantly gauged catchments, particularly in developing countries like India, where adequate historical runoff data are generally not available.