Estimation of Parameters of a Conceptual Water Balance Model for Ungauged Catchments

The problem of parameter estimation constitutes the largest obstacle to successful application of conceptual catchment models in ungauged catchments. This paper investigates the usefulness of a conceptual water balance model for simulating river flow from catchments covering a wide variety of climatic and physiographic areas. The model is a 6-parameter water balance model which was applied to 26 seasonally snow covered catchments in central Sweden. The model was calibrated on a group of catchments and the calibrated parameter values related to physical catchment indices. The relationships were tested by comparing observed and simulated runoff records from 4 catchments that were not contained in the regression analysis. The results show that the model can be satisfactorily applied to ungauged basins in the study region. In order to test the physical relevance of the model to a wider set of conditions, the model was modified by excluding the snow routine part. The resulting model and the same technique were tested on 24 catchments taken from northern Belgium. The verification results were found to be satisfactory.