How crucial is it to account for the antecedent moisture conditions in flood forecasting? Comparison of event-based and continuous approaches on 178 catchments

摘要

This paper compares event-based and continuous hydrological modelling approachesfor real-time forecasting of river flows. Both approaches are compared usinga lumped hydrologic model (whose structure includes a soil moisture accounting(SMA) store and a routing store) on a data set of 178 French catchments. Themain focus of this study was to investigate the actual impact of soil moistureinitial conditions on the performance of flood forecasting models and thepossible compensations with updating techniques. The rainfall-runoff modelassimilation technique we used does not impact the SMA component of the modelbut only its routing part. Tests were made by running the SMA store continuouslyor on event basis, everything else being equal. The results show that thecontinuous approach remains the reference to ensure good forecasting performances.We show, however, that the possibility to assimilate the last observed flowconsiderably reduces the differences in performance. Last, we present a robustalternative to initialize the SMA store where continuous approaches areimpossible because of data availability problems.