RAINFALL-RUNOFF MODEL ACCURACY FOR AN EXTREME FLOOD

Relatively little is known about the accuracy of conceptual rainfall-runoff model simulations of extreme floods. A case study is used to evaluate the accuracy of runoff model simulations of the 100-year flood of July 1, 1978 on the Kickapoo River (drainage area = 690 km(2)), in southwest Wisconsin. The accuracy of a simple and quick analysis is compared to that of an elaborate, labor-intensive analysis. The more elaborate modeling approach produces more accurate results, although significant errors for the peak discharge and runoff volume are observed in both approaches. The potential sources of uncertainty in the results are evaluated. Error in the precipitation data used for calibrating the model appears to be the primary source of uncertainty.