A time series tool to support the multi-criteria performance evaluation of rainfall-runoff models

A multi-criteria model evaluation protocol is presented to check the performance of rainfall-runoff models during model calibration and validation phases based on a high frequency (e.g. hourly, daily) river flow series. The multiple criteria or objectives are based on multiple and non-commensurable measures of information derived from river flow series by means of a number of sequential time series processing tasks. These include separation of the river flow series in subflows, split of the series in nearly independent quick and slow flow hydrograph periods, and the extraction of nearly independent peak and low flows. The protocol accounts for the statistical assumptions and requirements on independency and homoscedasticity of the model residuals, significantly advanced through the use of nearly independent flow values extracted from the flow series. Next to the separate evaluation of the subflow recessions, the quick and slow runoff peak and low values and event volumes, also the performance of the model in predicting extreme high and low flow statistics is validated. To support the time series processing tasks as well as the application of the multi-criteria model evaluation protocol, a Microsoft Excel-based tool (WETSPRO: Water Engineering Time Series PROcessing tool) has been developed. It is based on the assessment of graphical displays, which complement traditional goodness-of-fit statistics.