Hydrological ensemble forecasting at ungauged basins: using neighbour catchments for model setup and updating

摘要

In flow forecasting, additionally to the need of long time series ofhistoric discharges for model setup and calibration, hydrological modelsalso need real-time discharge data for the updating of the initialconditions at the time of the forecasts. The need of data challengesoperational flow forecasting at ungauged or poorly gauged sites. This studyevaluates the performance of different choices of parameter sets anddischarge updates to run a flow forecasting model at ungauged sites, basedon information from neighbour catchments. A cross-validation approach isapplied on a set of 211 catchments in France and a 17-month forecastingperiod is used to calculate skill scores and evaluate the quality of theforecasts. A reference situation, where local information is available, iscompared to alternative situations, which include scenarios where no localdata is available at all and scenarios where local data started to becollected at the beginning of the forecasting period. To cope withuncertainties from rainfall forecasts, the model is driven by ensembleweather forecasts from the PEARP-Météo-France ensemble predictionsystem. The results show that neighbour catchments can contribute to provideforecasts of good quality at ungauged sites, especially with the transfer ofparameter sets for model simulation. The added value of local data for theoperational updating of the hydrological ensemble forecasts is highlighted.