Study On Water-Sediment Characteristics And Numerical Simulation On Erosion-Deposition Evolution Of The Middle Huaihe River And Hongze Lake

Flood disasters occurred frequently in the Huaihe River Basin,under the guidance of the policy of ’ Balancing storage and discharge ’,a comparatively perfect flood control system has been gradually formed.However,some key issues remain unresolved.Thus,this paper aims to clarify the characteristics and the exchange regularity of water-sediment in the process of watershed management,explore the stability and evolution trend of the middle reaches of Huaihe River,and reveal the response of water-sediment transport and erosion-deposition evolution of riverbed and lake basin under changing conditions.So the paper carried out the following research,the study on water-sediment characteristics and exchange degree of river and lake,the study on chaotic characteristics of river in multivariate time series,the river stability analysis based on non-equilibrium thermodynamics theory,the optimization of artificial neural network hydrological model prediction model,numerical analysis of water-sediment transport law and evolution response of riverbed and lake basin under typical conditions.The main research results are as follows:(1)The characteristics of water-sediment in the Huaihe River and Hongze Lake were analyzed in detail by extending the length of time series and cross-complementing various statistical test methods,which improved the comprehensiveness and accuracy of the analysis of water-sediment characteristics of river and lake.Establishing the determination index of water-sediment exchange intensity between river and lake,analyzing the variation law of water-sediment exchange intensity between river and lake,and clarifying the stable relationship of water-sediment interaction between river and lake.(2)Based on the hydrological data of Huaihe River,the stability and development trend of the river were judged based on the excess entropy production,the stability of the river bed was analyzed according to the theory of minimum rate of energy dissipation.The applicability of the river stability analysis method based on the non-equilibrium thermodynamics theory in the Huaihe River is verified,and formed a set of analysis methods suitable for the stability judgment and development evolution trend of the Huaihe River。(3)Based on multivariate time series,combined with chaos theory,weights of factors influencing river bed evolution were determined by information entropy theory,the chaotic characteristics of different reaches of the Huaihe River were proved by various methods.(4)The two-dimensional water and sediment mathematical model of the middle Huaihe River and Hongze Lake was constructed,which was consistent with the watersediment characteristics of Huaihe river basin.Numerical calculation was carried for the measures to control the flood disaster in the basin,for example,expanding the discharge of Hongze Lake,expanding the capacity of the main river channel and excavating the Fengtieying diversion river,and found out the reduction effect of flood level,the law of water-sediment transport,and the response of erosion and deposition evolution between riverbed and lake basin.(5)A 30 years long series of water-sediment time series with the periodic wet-dry transformation of water-sediment in the Huaihe River was established,which clarified the long-term effects of water-sediment changes on the evolution of river and lake erosion and deposition.It provided a theoretical basis for the further prevention and control of flood disasters in Huaihe River basin.