Research Of Parameter Migration And Hydro-hydrodynamic Coupling Model In Hanjiang River Basin

In recent years,the frequency of extreme weather is increasing.And flood disasters are occurring with an increasing frequency.Accurate simulation of river flood routing has become an important basis for flood control.One-dimensional hydrodynamic model is mainly used in traditional flood routing simulation.But the inflow data needed for modeling is often difficult to obtain which limits the improvement of simulation accuracy.Based on this problem,this paper takes the Hanjiang River Basin as the research area.The coupling model of hydrology and hydrodynamics is established by means of external coupling.And The runoff simulation function of hydrology is used to provide boundary conditions for the hydrodynamic model.The main research contents and results of this paper are as follows:（1）Due to the limited measured data,the research area is divided into the reference basin,the validation basin and the no-data basins.First,the SWAT model is established.Based on GLUE algorithm and measured daily runoff data,the hydrological parameters are calibrated.The Nash-Suttcliffe efficiency coefficient and determination coefficient in the calibration period are 0.77 and 0.78.During the verification period,they are 0.74 and 0.75.The results show that SWAT model is suitable for runoff simulation of Hanjiang River Basin.（2）Based on the hydrological similarity principle,typical indicators with significant influence on runoff are selected to construct a hydrologic similarity index system.And weights are determined by the variation coefficient method.The hydrological similarity values between the basins are calculated.The hydrological similarity values of Lengshui River Basin and Huangyang River Basin are 0.70 and 0.71.The values of other basins are bigger than 0.75,which means they are basically similar.According to the hydrologic similarity evaluation criteria,parameter transplantation can be carried out.（3）The parameters of the reference basin are transplanted to the validation basin and the no-data basins.The runoff is simulated.After comparison with the measured runoff data,it is verified that Ens and R² in the basin are 0.75 and 0.78 respectively.The correlation coefficients between monthly average rainfall and monthly average runoff in the basins without measured data are all above 0.90.From 1975 to 2009,the average annual runoff of Nankuanping Hydrological Station in Jinqian River Basin is 896.3 million m³.The simulation result after applying the parameter transplantation method is 900.3 million m³.The relative error is only 0.74%,which meets the requirements of runoff simulation.（4）Hydro-hydrodynamic external coupling model is established in HydroInfo.Based on Saint-Venant equations,the model is solved.In order to verify the advantages of the coupling model and the reliability of the results,two one-dimensional hydrodynamic control models are established（zero tributary inflow and constant inflow）.And the measured runoff data were used for verification.The L₂ error of the coupling model is 0.090.And the relative error of the peak flow is only and 0.10%.Both are much smaller than the error values of the control model.The result shows that the coupling model established in this paper is reliable and can be used for flood forecasting and flood routing simulation in this region.Based on the above research results,this paper verified the applicability of SWAT model and parameter transplantation method in the Hanjiang River Basin.It also provides a solution for the shortage of flow data encountered in the process of hydrodynamic modeling.And the flood routing model of Hanjiang River Basin is established to provide reference for flood control and disaster reduction in this area.