Numerical Simulation On Dam-Break Flooding Of Cascade Reservoirs In The Yalong River Basin

Water is a precious resource for human survival and development.In order to make more rational use of limited water resources,people build dams and store water.A reservoir could have comprehensive benefits such as flood control,power generation,irrigation,and aquaculture etc.,but once wrecked,it will have catastrophic consequences.Only by mastering the relevant laws can we prevent problems before they happen.This article focuses on the problem of dam-break flood in cascade reservoirs,with the numerical simulation method in the actual situation the Yalong river basin,to explore the single reservoir failure modes and the process of collapse flow,the dam-break flood in cascade reservoirs and their damage to the downstream areas,and the reduction of flood damage.By analysing the corresponding results drawn from the researches above,we can make some conclusions which can provide reference for the related researches on other dam-break flood in cascade reservoirs.The main research contents and results of this article are as follows:1)Research on the single reservoir failure modes and the process of collapse flow.Based on the larger reservoir Jinping NO.1 in the Yalong river basin,it assumes that the dam was different dam type,such as gravity dam,arch dam and earth-rock dam;and it analyzes its possible collapse process,instantaneously broken or gradually broken,and then the way of collapse,including vertical collapse,lateral collapse and gradual erosion of the breach.The results show that the lateral collapse is more harmful than the vertical collapse when the equal area is instantaneously broken,and the more obvious the smaller the collapse area is;the peak of the fracture flow of gradually broken is obviously smaller than the instantaneously broken,but the higher flow maintenance time is much longer than the latter.2)Research on the failure modes of cascade reservoirs and their damage on the downstream areas.Based on the five cascade reservoirs that have been built in the Yalong river basin,it designs,scientifically and reasonably,some scenarios of dam-break in cascade reservoirs considering the positional relationship,storage capacity and dam types of them.In this way,the corresponding researches on the floods in cascade reservoirs,the evolution of floods,the response of downstream cascades and the floods damage on downstream areas are carried out.The results show that the peak of the fracture flow of the downstream cascades is greater when the collapse is caused by the upstream faultless floodthan by the super standard flood;the flooding range of the downstream areas caused by the floods in cascade reservoirs is related to both the peak of the fracture flow in the last cascade and the total storage capacity of the collapsed reservoirs;the flooding duration of the downstream areas has little to do with the peak of the fracture flow in the last cascade,and is greatly affected by the response states,collapse on the dam top or not collapse,of the downstream cascades in the floods.3)Research on the reduction of flood damage of cascade reservoirs.On the basis of the researches on the floods of the cascade reservoirs in the Yalong river basin,it aims at the corresponding measures from the perspective of reducing the flood damage,on the ground of that the floods are caused by the failure of the larger reservoir Jinping NO.1 or Ertan in the river basin.The results show that the advancement of the water level of the downstream cascades to dead water level,or the early blasting of the downstream cascades,can both alleviate the possible future disasters.