Research Of The Flood Forecasting Considering The Influence Of Water Conservancy Project

Flood forecasting is an important component of non-engineering measures for flood control.It is the most important basis for the process of reservoir control operation.How to improve the accuracy of forecasting is a research hotspot.In recent years,in order to meet the needs of social development and people's life,many areas builded a large number of small reservoirs,dams and other wading projects in the basin,human activities have become an important factor affecting the flood process.In this paper,the DHF model,TOPMODEL model and HEC-HMS hydrological model were selected to consider the effect of water conservancy project on rainfall runoff.And applied to Menlou and Qinghe reservoir watershed where there are numerous small and medium-sized reservoirs.The main research contents and results are summarized as follows:(1)Through the analysis,the influence of a large number of water conservancy projects on floods is mainly manifested in the function of regulation and regulation.In this paper,three methods are used to consider the effect of water conservancy project on the runoff of the basin: Method 1,replacing the reservoirs with a virtual reservoir;Method 2 grouping the small reservoirs separately,dividing the area controlled by each small reservoir;Method 3,according to the characteristics of the basin divided the basin into many sub-watershed,the water conservancy project which e located in the same sub-basin been see into a reservoir.And the dynamic change of parameters is used to reflect the influence of small water conservancy project on confluence.On the basis of the original structure,the influencing module of water conservancy project is added to the runoff,and improved the confluence module in the TOPMODEL and DHF model.The idea of flood forecasting is described after adding the polymerization reservoir in HEC-HMS hydrological model in detail.(2)The improved DHF and TOPMODEL and HMS-HEC models were applied to the Menlou reservoir basin,and the simulation results are compared with the results of the improved DHF model.The results show that using the improved TOPMODEL model in two ways to consider the impact of water conservancy projects within the basin,flood forecasting program significantly improved accuracy.The qualified rate of the runoff simulation and confluence simulation is more than 80% of the regular and inspection period,which can better reflect the influence of water conservancy project on runoff.And the HEC-HMS was used to simulate the flood,thhe qualified rate is 77% in the simulation of runoff,80% in the verification period,88% in the convergence simulation rate,78% in the verification period and only the second level of the flood forecasting scheme.From the accuracy of flow simulation,the accuracy of confluence simulation and the fitting degree of flooding,the improved DHF model is more suitable for the flood forecast of the Men Lou reservoir and can rovide a reliable basis for the reservoir scheduling.(3)The improved TOPMODEL,DHF model and HEC-HMS were applied to Qinghe Reservoir.Flood simulation and parameter optimization for 22 historical floods.The results show that without considering the impact of water conservancy projects,the original DHF model and TOPMODEL were used to simulate the historical floods in the Qinghe reservoir watershed.The results of the runoff were better,but the convergence results were very poor,there are 8 unqualified floods in the DHF model,10 unqualified floods in the TOPMODEL,the regulation of runoff in the basin is obvious.Using the improved two models for flood simulation,the yield rate was not significantly improved compared with that before.But the convergence accuracy is improved obviously,and the pass rate of the two models is not less than 80% on rate period and the inspection period.Compared with the TOPMODEL model,the improved model model shows better applicability.In the development of Qinghe Reservoir flood forecast program can choose the DHF model.In the HEC-HMS model,a virtual reservoir was used to simulate the 22 floods of Qinghe Reservoir.Production pass is very low pass rate,does not apply to the Qinghe River Basin flood simulation,the model is more suitable for mountain flood warning.(4)It can be seen from the simulation results that the DHF model of the lumped hydrological model shows a better simulation effect.The existing distributed watershed hydrological model can not test the accuracy of sub-basin simulation results due to the limitation of data accuracy such as rainfall,evaporation and terrain at the present stage.So the simulation results of the hydrological model with distributed attributes are not ideal.In summary,when developing a flood forecasting scheme,the spatial scale of existing rainfall,evaporation,terrain data and other data should be an important factor in selecting hydrological models.