Ensemble Precipitation and Water-Level Forecasts for Anticipatory Water-System Control

Abstract

A method is presented for testing weather forecast products for applications in anticipatory water-system control. The applicability of the ensemble prediction system (EPS) of the ECMWF is tested for flood control in a regional water system in the Netherlands. By performing long-term verification analyses, a full range of probability-threshold-based decision rules to apply anticipatory control actions is evaluated in terms of hits (correct alerts), missed events, and false alarms. The analysis includes forecast horizons from 3 to 9 days for extreme precipitation events and extreme water-level events. The water-level forecasts are prepared by feeding each member of the ECMWF EPS precipitation ensemble into a deterministic water-system control model. The current operational strategy is modeled to forecast when the routine operational control will not be sufficient to prevent high water levels, and therefore anticipatory control actions are needed. The results show that ECMWF EPS precipitation forecasts contain useful information for regional water-system control in the Netherlands. All critical events during the analysis period were forecasted. The applied analysis method allows water managers to define decision rules, on the basis of requirements, in terms of forecast horizon, safety, and allowable costs of adverse effects of false alarms.