Research On Flood Forecasting Method Of Rongjiang River Basin Based On Land-air Coupling

The short-term runoff forecast is of great significance to the operation of the reservoir.The timely and high-precision flood forecast can gain more precious time for flood prevention and disaster reduction and flood utilization.On the basis of ensuring the accuracy of flood forecasting,this paper takes the extension of the forecast period as the primary research goal,and takes the Rongjiang River Basin controlled by the Mashi Hydropower Station as the research object.Firstly,the flood forecasting scheme of the river basin is analyzed and established,and then the ECMWF precipitation numerical forecasting information is introduced to carry out the meteorological and hydrological information coupled flood forecasting research.The forecast period of the flood forecast in this basin is 24 h ahead.The main research contents of this article are as follows:(1)Based on the measured hydrological data in the Rongjiang River Basin controlled by the Mashi Hydropower Station,the empirical regression model is first used to explore the flood forecasting scheme of the river basin.A regression model of accumulated rainfall before the rain peak in the river basin and the measured flood peak discharge is proposed.The regular pass rate is 82%,and the pass rate during the inspection period is 70%.(2)In view of the inadequacy of the empirical regression model to describe the characteristics of the watershed,the hydrological model of the Xinanjiang reservoir full runoff was selected as the runoff forecast model for the runoff calculation.Out of three types of seven unit lines in the basin.The parameters of Xin'anjiang model were used for calibration.The rate of passing flood forecast during the period was 86%,the rate of passing forecast was 86%,the rate of passing forecast during the inspection period was 100%,and the rate of passing forecast was 90%.The results show that the Xinanjiang flood-produced runoff model has good applicability in the flood forecast of the Rongjiang River Basin.(3)Adopt the numerical precipitation forecast information released by ECMWF,take the actual precipitation data of the watershed as a reference,use the surface rainfall estimation method to convert the grid data of the precipitation forecast into surface rainfall data,and use the current TS score,BS score and other evaluations Methods The ECMWF integrated forecast system was evaluated.The results show that the accuracy of ensemble forecasting is higher than that of deterministic forecasting,and ECMWF has a certain forecasting effect for different accumulated precipitation magnitudes,and it has a good applicability in this basin.(4)The ECMWF precipitation aggregate forecast data is used as precipitation input to drive the Xin'anjiang model for flood forecasting in the basin.The results of flood forecasting using ensemble forecasting show that ensemble can effectively describe the uncertainty of flood forecasting and give the effective range of flood flooding.The ensemble arithmetic average method is used to revise the ensemble forecast product,and it is used as the input value of the Xin'anjiang flooded runoff model for forecast research.The results show that the arithmetic mean correction product can eliminate the forecast error caused by the extreme value forecast to a certain extent.Under the premise of maintaining the accuracy of the flood forecast,the forecast period of the flood forecast in the basin is advanced by 24 hours.