Study On Optimal Water Resources Allocation Methods For Jiangsu Section Of South-to-North Water Diversion East Route Project

The South-to-North water diversion project is a national strategic engineering to further realize the water resources optimal allocation in our country. When the project is completed, it will be a great action for solving the serious water shortage problem in northern China, so as to provide a basis guarantee for sustainable development of China’s economic and social protection. The east route project is located in the lower reaches of Yangtze River, Huaihe River, Yellow River and Haihe River basin, involving five provinces and cities of Tianjin, Hebei, Shandong, Anhui and Jiangsu, Therefore it is a large-scale inter-basin water diversion project includes multiple water sources, multiple users and multiple stages. The first phase project has started its construction in2002and will transfer the water from Jiangsu to the north of China after the project is completed in2013. In view of this, how to carry out a scientific and rational scheduling for the complex water supply system will be a very meaningful and necessary research topic.At present, the water resources system optimization problem has attracted widespread attention, scholars at home and abroad do a lot of research on the theory and application of optimal allocation of water resources of the water supply system and get a lot of experience and results. Since the1960s, the simple methods of operations research was the major method to solve the water resources system problems. However, with the gradual deepening of the research questions, the traditional optimization theories and methods in dealing with non-linear, high-dimensional, multi-target, multi-constraint issues become increasingly constrained. In recent years, With the continuous development of modern applied mathematics and computer technology as well as the increasingly prominent contradiction between water supply and demand, the calculation methods of artificial computational intelligence such as genetic algorithms, simulated annealing, ant colony optimization algorithm have been proposed to deal with the complex system optimization problems. These methods have played a huge role for the optimal allocation of water resources by using the modern computer as a tool. On the basis of domestic and foreign related research, this paper analyzes systematically the optimal allocation of water resources for Jiangsu section of South-to-North Water Diversion East Route Project from the two aspects of theory and practice. The main research content and conclusions include the following aspects:(1) Combined with the basic situation of the first phase of South-to-North Water Diversion East Route Project in Jiangsu Section, this paper generalizes the complex water supply project into a rivers-lakes-pumping stations system, which is composed of three regulating reservoirs, nine-stage lift pumping stations, several diversion channels and five kinds of water users (including agriculture, industry, life, eco-environment and lock). On this basis, this paper analyzes the actual situation in various engineering, such as the scale and controlled water level of the water storage projects, the layout and water conveyance capacity of the water diversion projects, the scale and working hours of the lifting Projects and so on. At the same time, this paper classifies and generalizes the water users in each intake area, analyzes and calculates the runoff situation and water demand in each hydrological year.(2) A dynamic programming model with multiple decision variables for optimal water resources allocation of river-lake-pumping stations system is proposed, in which minimum sum of squares of water shortage (discarded water) in each section is set as the objective function, the water storage of the lake of each stage is defined as the state variable, the water volume to be pumped into the lake and the water release from the lake are expressed as decision variables. The Yangtze River-Hongze Lake section of South-to-North Water Diversion Project is taken as a case study. According to the characteristics that the discrete values of the state variable are relatively less while the feasible solution space of each decision variable is large and its more discrete values, this paper applies a hybrid method (DP-SA) using dynamic programming and simulated annealing combined by the authors to calculate the model. The application results show that using the proposed model to make optimal operation not only can improve the water-supply guaranteed rate, but also can decrease the water volume to be pumped which can reduce the operation cost of the water supply system. In comparison to dynamic programming with successive approximations(DPSA), we can obtain that the proposed hybrid method has better calculation results and faster convergence rate in solving this kind of problem.(3) In order to better solve the problem of water resources allocation in inter-basin water diversion project, this paper puts forward an optimal water resources allocation model for rivers-lakes-pumping stations system by combining simulation technology and discrete differential dynamic programming(DDDP) on the basis of the conventional water resources allocation. The model takes the minimum water shortage and pumping water volume as comprehensive objective function:At first, according to certain operation rules of lake, the inflow and water use in different hydrological year were simulated and calculated in order to determine the maximum available water supply volume and transferred water volume of each section. Based on this, a dynamic programming model for joint operation of multiple lakes is proposed, in which the minimum pumping water volume of the whole system is set as the objective function, the water volume to be pumped into the lake or discarded water from the lake is expressed as decision variable, and is solved by means of DDDP. The JiangSu section of South-to-North Water Diversion Project is taken as a study case, the results show that not only the water supply guaranteed rate of the whole system can be improved but also the equilibrium allocation of water supply volume among each section and each period can be realized. Secondly, by using the above mentioned model, we can obtain the maximum transferred water volume1408,1418and1270million m3out of JiangSu province in50%,75%and95%hydrological year. Thirdly, we can decrease the total pumping water volume5134,9487and2819million m3in50%,75%and95%hydrological year which can reduce the cost of the water supply system through optimal operation, and finally realize optimal joint allocation of local and transferred water resources.