THE INFLUENCE OF MODEL PARAMETERS ON CATCHMENT RESPONSE

This paper deals with the study of influence of conceptual rainfall-runoff model parameters on catchment response. A lumped conceptual watershed yield model, based on pragmatic approach, is employed to study the influence of model parameters on catchment response i.e runoff. The model is calibrated using manual parameter fitting approach also known as trial and error parameter fitting. In all, there are parameters that control the functioning of the model. The detailed analysis was performed on Ling River near Kahuta having catchment area of 145.04 sq. km. (56 sq. miles). The model includes physical parameters linked with groundwater storage, evapotranspiration and coefficients of infiltration & groundwater storage, and initial estimates of the surface water and groundwater storages. As sensitivity analysis is a very useful tool for parameter optimization therefore, it was performed to evaluate the influence of model parameters on runoff. The sensitivity and relative contributions of model parameters influencing catchment response are studied. The analysis confirmed that model parameters linked with surface runoff parameters specified for each month are more significant as compared to infiltration, evapotranspiration and subsurface input parameters.