Quantitative evaluation of developed GIUH for small water - sheds of Satluj and Markanda catchements of Himachal Pradesh

Watershed has long been identified as the most rational unit for planning and implementation of the programmes dealing with agricultural production. To estimate the watershed response due to different storm patterns, event based model, GIUH was developed in this study. GIUH model is based on storm basis incorporating geomorphological parameters with the hydrological characteristics of the basin. Geomorphological parameters are derived from different maps of the watersheds satisfying Horton's law when ordered according to Strahler ordering procedure. The experiment has been carried out to develop instantaneous unit hydrograph based on GIUH model and calibrated using the observed direct runoff hydrograph (DRH) data. DRHS obtained from GIUH are compared with the observed DRHS to validate the developed model. To test the performance of the developed model, necessary data were obtained from two test small watersheds namely Arki and Mandapa of Himachal Pradesh. Coefficient of efficiency, relative squared error, absolute relative error in computed peak flow rates, and coefficient of residual mass were used as the performance criteria of the GIUH model. The percentage absolute error in time to peak between computed and observed direct runoff hydrographs was found to be zero percent. The regressional relationships between the hydrological variables were estimated with coefficient of determination nearer to unity.