Water System Based On Optimal Allocation Of Water Resources

China is short of water resources,the per capita share of water resources is small,and the contradiction between supply and demand of water resources is prominent.At the same time,with the growth of water consumption demand,various environmental problems and ecological problems caused by water shortage also began to enter the public view.In order to solve the problems of water resources shortage,water ecological damage and water environmental pollution,the report of the 19 th National Congress of the Communist Party of China puts water resources in the first place of the nine major infrastructure construction,and focuses on solving the imbalance in the development of water resources.At the same time,river lake system connectivity is a necessary measure for water ecological restoration and water environment improvement.It is of great significance to study the definition,concept and evaluation system of river lake system connectivity for river ecological restoration and sustainable development of river lake ecosystem.Aiming at the problems of Langfang City,such as insufficient water resources endowment,serious over exploitation of groundwater,lack of guarantee of local water supply and so on,this paper uses the optimal allocation model of water resources to predict water demand and analyze the balance between supply and demand.This paper analyzes the connotation of water system connectivity,selects the indicators of water system connectivity based on graph theory and water resources allocation network diagram,analyzes the indicator system by kmo test,principal component analysis and set pair analysis,and then constructs the comprehensive evaluation index system of water system connectivity in Langfang city.The results are compared with the 13 th five year plan of Langfang city and the comprehensive evaluation index system of water system connectivity in Langfang city The ecological comprehensive planning of Langfang city compares the results of current situation investigation and future planning evaluation of Langfang city.The main achievements are as follows(1)Based on the investigation and analysis of the water resources conditions of Langfang City,the economic development trend,water demand and water supply of Langfang City in the planning level year are predicted.Based on the idea of three-time balanced allocation,the population and economic output value of Langfang City in 2020,2025,2030 and 2035 under the recommended scheme are calculated by using the optimal allocation model of water resources.Under the recommended scheme,Langfang city implements the enhanced water-saving mode and medium speed economic development.Combined with the operation of the middle route and the East Route of the south to North Water Diversion Project,and by increasing the sewage reuse rate,sewage treatment rate,adding rainwater reuse measures and other ways to increase the reuse water and the amount of rain and flood,the water supply composition of Langfang City in 2035 has been further improved and optimized,The proportion of other types of water supply increased,and the water shortage rate of the whole city decreased from 23.03% in the base year to 3.17%.(2)By evaluating the connotation of water system connectivity,it is found that water system connectivity has the dual attribute of "nature society" and the attribute of scale transformation.Different from the previous definition of water network of rivers and lakes,domestic drainage,industrial drainage and other water consumption and drainage pipe networks are connected to the water system,forming an artificial side branch water circulation system composed of four basic links of supply use consumption drainage.Combined with the scale transformation attribute,the national scale large water network is connected with the regional scale small water network through supply,consumption and drainage,To achieve the specific transformation from the large level to the small level,we can allocate water resources more accurately and reasonably on a small scale,and at the same time,it has a full sense of social attributes.(3)Based on the evaluation system of natural water system connectivity based on graph theory,starting from the definition of water transmission system(line)of calculation unit in the network diagram of water resources optimal allocation system,according to the water transmission relationship included in the artificial side branch water circulation system,combined with the evaluation index of production and living water level,the concept of node and corridor based on graph theory and landscape ecology was expanded,Eight indexes are selected to construct the natural artificial binary index evaluation system of river system connectivity.Kmo test and principal component analysis are used to test the correlation and explanatory power of the selected indexes.The results show that the water system connectivity of Langfang City in the past,present and future is basically consistent with the evaluation results of current situation investigation and future planning.(4)The ecological flow of the main rivers in Langfang city is predicted and analyzed.With the improvement of the connectivity level,the water shortage rate of Langfang city is gradually decreasing.Compared with the current situation,the river cut-off situation is serious.In the future,with the improvement of the connectivity level,the main rivers in the city will not only meet the minimum ecological flow,but also increase the predicted value of river water.