Study On Hydrological Model And Parameter Regionalization In Lack-data Watershed

As an important part of hydrological model,model parameters are generally obtained through the calibration of long-term hydrological historical data.However,with the change of climate and land use,there are many basins without historical data or historical data damaged.In the lack-data watershed,some model parameters are difficult to determine.In order to reduce the uncertainty of hydrological model parameters,a variety of hydrological models and their regionalization methods have been proposed gradually,but there are still problems such as complex model structure,many parameters,some parameters are difficult to regionalize,and regional applicability.Therefore,it is necessary to study the regionalization of hydrological model and its parameters,not only from the perspective of promoting the development of hydrological theory,but also from the perspective of improving prediction accuracy,reducing prediction uncertainty and providing reliable basis for scientific management and decision-making of water resources.Based on this,the applicability and parameter regionalization of HEC-HMS model in small watershed of Hilly Area IV of hydrological division in Henan Province are studied.In this paper,two kinds of runoff yield concentration combinations with less physical meaning are set up for HEC-HMS model:(1)SCS Runoff Curve and SCS unit hydrograph;(2)Initial and constant rate and Snyder unit hydrograph.Luanchuan,Gaocheng,xiahecun and Zhongtang are the representative watersheds in the study area.The main research contents and achievements are as follows:(1)A digital watershed database was established.Using Arc GIS to process the digital elevation,soil and land use data of the basin,the drainage system of the basin is extracted,and each basin is divided into several sub basins,and the digital drainage basins of Luanchuan,Gaocheng,xiahecun and Zhongtang are established,which provides reliable basic data for the model construction and parameter regionalization applicability research in this paper.(2)An automatic optimization and calibration method for HEC-HMS model is proposed.In this paper,using the simplex method,taking the peak weighted root mean square error function as the objective function,the selected typical floods are calibrated to obtain the range of basin parameters.The range is input into the multi-objective genetic algorithm(e NSGA-II)framework of HEC-HMS model.The four objectives are the average relative error of runoff depth,the relative error of flood peak discharge,the number of qualified fields at peak time and the Nash efficiency coefficient The function is used to constrain,and the combination of model parameters is obtained.(4)A runoff model suitable for small watershed in the study area is selected.The HEC-HMS model is applied to flood simulation of Luanchuan,Gaocheng and xiahecun basins.The results show that the runoff Runoff Curve and SCS unit hydrograph are simple in structure,few in parameters and high in simulation accuracy,which can reach the level of B-level forecast.The first loss and second loss method and Snyder unit hydrograph are used in the flood simulation of Luanchuan,Gaocheng and xiahecun basins The simulation accuracy is only level C.(5)The parameters of SCS Runoff Curve and SCS unit hydrograph are regionalized by parameter regression method.By analyzing the physical causes of SCS Runoff Curve,SCS unit hydrograph model parameters and watershed underlying surface eigenvalues(forest coverage,soil moisture content,soil infiltration,river length,watershed slope),and quantifying the main characteristic indexes related to the parameters,a multiple regression relationship between the watershed runoff model parameters and watershed underlying surface eigenvalues is established,which directly The results show that the flood process simulation is good and the simulation accuracy reaches the level B,which shows that the model and its parameter regionalization method proposed in this paper are feasible and effective.