The Flood Risk Analysis Of The Dam Break And Overflow Floods In Ningxia Section Under The Encounter Of Floods In Mainstream And Its Tributaries

Along with the expansion of cities and human,the loss of the flood disaster is increasing,especically the loss in human life and property in socal and economic rsults from the dam-break flood.One of the most effective ways to implement flood management is forecasting the flood through the method which is constructing the coupling numerical simulation between the river levee breaches and protection zone.We chose the channel between the Xiaheyan to Qintongxia and the conservation area which is in the left and right rank of the channle to study,Creating the numerical model of collapse and overflow floods on the basis of the flood analysis in this article.The flood damage elements according to the flood scheme were used to carry out flood loss analysis and evaluation,thus providing reference to the flood managers and ecomonic constructors.(1)The flood composition analysis under the encounter of floods in mainstream and its tributaries.We built the joint distribution in mainstream and its tributaries based on Copula function,then the composition of the flood elements which were most likely happen in mainstream and its tributaries were calculated by the method of the most likely composition.Results show that the design flood in the Qingtongxia section is mostly from the mainstream in the upstream section of the Yellow River,and along with the level of design flood is rising;the flood allocation in the tributary was increasing,it is not reasonable to ignore the influence of the tributary in reservoir inflow flood analyzing.The results in the method of the equivalent frequency composition and the method basing on copula function are in agreement.Basing on the design flood results and the general situation of the Qingtongxia Water Control Project,we can obtain the results in the reservoir flood routing risk analysis in the hundred-year flood scheme.(2)The bulid of the numerical model of collapse and overflow floods.Center format of finite volume method is adopted to establish the two-dimensional hydrodynamic model,by the method of Abbott implicit format at six the governing equations are dispersed to simulate the water level and flow rate of river along with times and the changes in one dimensional space,the river in one dimensional space and protection zone in two dimensional space are coupled by lateral linking.The selected of the dam breach is determined by considering with the elements of river terrain?historic flood?levee standard?overflow situation and the situation of dike breach,we choose the Shuangqiao and Qingxingqukou as the dam breach which is bulit in one-dimensional hydrodynamic model,and bulit the coupled numberical model by lateral linking The coupled numberical model which is based on the collapse and overflow floods established in this article not only can simulate well the dike burst in the actual engineering projects,but also make results of the coupled numberical model to approaching the real flood process,which can improve the reliablity and accurancy of the calculation results.(3)The flood damage assessment and impact analysis model are bulit basing on spatial information.Through the impact analysis of flood and the flood damage assessment basing on the flood analysis,we can get the Social economic loss parameter values under different water depth grading and villages,which providing a reference to the flood managers and ecomonic constructors.