Coupling ensemble weather predictions based on TIGGE database with Grid-Xinanjiang model for flood forecast

摘要

The incorporation of numerical weather predictions (NWP) into a floodforecasting system can increase forecast lead times from a few hours to afew days. A single NWP forecast from a single forecast centre, however, isinsufficient as it involves considerable non-predictable uncertainties andlead to a high number of false alarms. The availability of global ensemblenumerical weather prediction systems through the THORPEX Interactive GrandGlobal Ensemble' (TIGGE) offers a new opportunity for flood forecast. TheGrid-Xinanjiang distributed hydrological model, which is based on theXinanjiang model theory and the topographical information of each grid cellextracted from the Digital Elevation Model (DEM), is coupled with ensembleweather predictions based on the TIGGE database (CMC, CMA, ECWMF, UKMO, NCEP)for flood forecast. This paper presents a case study using the coupled floodforecasting model on the Xixian catchment (a drainage area of 8826 km2)located in Henan province, China. A probabilistic discharge is provided asthe end product of flood forecast. Results show that the association of theGrid-Xinanjiang model and the TIGGE database gives a promising tool for anearly warning of flood events several days ahead.