Coupling meteorological and hydrological models for flood forecasting

摘要

This paper deals with the problem of analysing the coupling of meteorologicalmeso-scale quantitative precipitation forecasts with distributedrainfall-runoff models to extend the forecasting horizon. Traditionally,semi-distributed rainfall-runoff models have been used for real time floodforecasting. More recently, increased computer capabilities allow theutilisation of distributed hydrological models with mesh sizes from tenths ofmetres to a few kilometres. On the other hand, meteorological models,providing the quantitative precipitation forecast, tend to produce averagevalues on meshes ranging from slightly less than 10 to 200 kilometres.Therefore, to improve the quality of flood forecasts, the effects of couplingthe meteorological and the hydrological models at different scales wereanalysed. A distributed hydrological model (TOPKAPI) was developed andcalibrated using a 1x1 km mesh for the case of the river Po closed at PonteSpessa (catchment area c. 37000 km2). The model was then coupled withseveral other European meteorological models ranging from the Limited AreaModels (provided by DMI and DWD) with resolutions from 0.0625° * 0.0625°, tothe ECMWF ensemble predictions with a resolution of 1.85° * 1.85°. Interestingresults, describing the coupled model behaviour, are available for ameteorological extreme event in Northern Italy (Nov. 1994). The resultsdemonstrate the poor reliability of the quantitative precipitation forecastsproduced by meteorological models presently available; this is not resolvedusing the Ensemble Forecasting technique, when compared with resultsobtainable with measured rainfall.