| In order to give full play to the flood control capacity of Yujiang river basin's existing cascade reservoirs,improve the flood control safety degree and reduction of its flood risk,this paper,aimed at the shortcomings of the predecessors'research method,introducted new technology and methods,used non-engineering measures,put Baise and Laokou cascade reservoirs of Yujiang river basin as the research object which combined with the flood discharge capacity of Nanning Yongjiang river levees,put GH-Copula(Gumbel-Hougaard Copula)function and improved genetic algorithm as technical support,to explore the problem of Baise and Laokou reservoirs and Nanning Yongjiang river levees united flood control operation.So that,to make a more efficient and safety project of cascade reservoirs united optimal flood control operation.First of all,in view of the insufficient considering of the correlation between flood peak and volumes when use the traditional single variable method to work out the design flood,this paper,introduced the GH-Copula function model and two variable return period concept,established a simultaneous distribution of flood peak and flood volumes whose marginal distribution is P-III type distribution,to ascertain the values of flood peak and flood volumes of design flood in different frequencies.These methods have considered the correlation between design flood peak and design flood volumes adequately,and the results are more reasonable,and more suitable for the situation that this drainage basin have combined action by flood peak and flood volumes,compared with the traditional single variable method.Secondly,although the traditional equal frequency design flood area composition method have considered the flood correlation between each partition with the design downstream from the perspective of "adverse to the flood control"factitiously,but it could not determine the correlation degree between each partition and downstream design section quantitatively,by the full use the spatial relationships between partitions and downstream from exist flood data series.By the use of GH-Copula function to establish the simultaneous distribution of design flood peak and design volumes which based on the spatial correlation of flood,ascertaining the design flood most likely areas composition by the use of strict mathematical method.The results are more objective and more in line with the actual situation of this drainage basin flood distribution.Finally,established cascade reservoirs optimal operation model of flood control.In view of the optimization problems when use traditional dynamic programming method to deal with these issues easy to fall into the "dimension disaster" and low efficiency,genetic algorithm is introduced which generation of initial population,and the choice of arithmetic,crossover and mutation parameters'determine have been appropriate improved to improve its optimize efficiency.By using improved genetic algorithm for the optimization model,this conclusion could be made that when Nanning happened once in 100 and 200 flood,after the Baise and Laokou reservoirs united flood control scheduling,the flood peak of Baise downstream had been cut down 74.51%and 72.76%,Nanning section have been cut down 15.56%and 18.04%,Compared with the original design report rate of flood peak peak clipping all have varying degrees of increase,Baise and Laokou reservoirs' flood control capacity have been made full use of.The highest flood water level of Nanning section were 80.40 m and 81.56 m,Compared with the original design report 81.88 m overflow water level lower 1.48 m and 0.23 m respectively,so that,not only the safty discharging of Nanning have been pretected,but also the flood risk of Nanning have been reduced and the ability to resist flood have been improved.The united flood control operation project has a certain reference value for the actual united flood control scheduling operation of Baise and Laokou reservoirs,in the future. |
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