Research And Practice Of A Distributed Coupled Atmospheric-Hydrological System In Flood Forecasting

As more and more reservoirs have been built and operated on the upper reach ofYangtze river，the joint operation of cascade reservoirs has been formed. However, theoperation of the upstream reservoirs not only increases the difficulty in the inflowforecasting of reservoirs on the downstream，such as Three Gorges Reservoir, but alsocut down the flood leadtime. While, the predicted period of traditional short-term rainfall-runoff forecasting model is limited, the forecatsing accuracy of long-term runoffforecasting model which is based on mathematical statistic method is low. As the guidingreservoir operation and management work, it is urgent to carry out the new floodforecasting method.To get high quality and short-term in-reservoir flow prediction ofThree Gorges Project (TGP), the TGP reservoir area is chosen as the research area. Fromthe perspective of weather-hydrological coupling forecast, the high resolution numericalatmospheric WRF (Weather Research and Forecasting) model was oneway coupled to theVIC(Variable Infiltration Capacity) model after temporal and spatial scale transformation,and the WRF/VIC oneway coupling model was established and applied in the WRF/VICCoupling Forecast System of the Three Gorges Project. The main results are as follows:(1) The distributed hydrological model was established in the three gorges reservoirarea. Based on the VIC grid model, taking the advantage of ArcGIS software to analysethe digital elevation (DEM), land use type, soil classification of remote sensing data, thevegetation, soil and flow of the parameter file ware made. The grid and daily distributedhydrological model was established as the land surface process model of land-air couplingsystem, providinga hydrological process simulation. And according to the three gorgesreservoir hydrologic meteorological observation data, the parameters of VIC model werecalibrated and the simulation effect of VIC model was tested.(2) Research on the coupling of WRF model and VIC model. Firstly, the temporaland spacial scale matching problem between numerical weather prediction model anddistributed hydrological model was reasearched. Secondly, the WRF model was onewaycoupled to the VIC model after temporal and spatial scale transformation to getquantitative rainfall and flood forecast with long leadtime. The results of quantitativerainfall and flood forecast accuracy inspection showed that WRF/VIC coupling flood forecasting system can effectively prolong the flood foresee period, improving theaccuracy of flood forecasting.(3) Application of WRF/VIC coupling flood forecasting method. Based on result ofWRF/VIC coupling model research, with the Server and distributed database technology,the WRF/VIC coupling flood forecasting system of Three Gogers Project reservoir areawas developed and applied to the Three Gogers Project. The WRF/VIC coupling floodforecasting system can prolong the inflow prediction of the Three Gorges Reservoir andimprove the accuracy of flood forecasting effectively. Now the WRF/VIC coupling fLoodforecasting system has formed a mature technology solution, and has been applied andverified on the flood forecasting project of cascade reservoirs of downstream of theJinshajiang River.