Ranking sensitive calibrating parameters of UBC Watershed Model

摘要

Almost in all hydrological models, calibrating parameters are tuned to best match the simulated results with the observed. In the present study sensitivity analysis was carried on the fifteen calibrating parameters of University of British Columbia Watershed Model (UBCWM). The study focuses to impart information to the modelers while calibrating UBCWM. To achieve the objectives of the study, UBC Watershed Model was applied on Chitral watershed in Pakistan. UBC Watershed Model is a semi distributed Hydrological model which divides the entire watershed in several elevation bands. The model was calibrated for the year 2006 with the coefficient of efficiency as well as the coefficient of determination equal to 0.94. The numerical values of the calibrating parameters were changed by increasing 20% and then by decreasing 20% of the standard calibrated values one by one. Sensitivity of the model was evaluated by computing the Absolute Sensitivity Index for each parameter. The sensitivity analysis results showed that the P0SREPO as the most sensitive parameter with 3.31525 Absolute Sensitivity Index (ASI) whereas C0IMPA found to be least sensitive giving a value of 0.0452 as Absolute Sensitivity Index (ASI). The logical trends in the results of sensitivity analysis show the robustness of the model.