Study On The Carrying Capacity And Optimization Of Water Resources In The Guanzhong Area Of The Weihe River Basin

China has proposed a national strategy for ecological protection and high-quality development in the Yellow River Basin,insisting on"fixing cities,land,people and production by water",and striving to build the Yellow River Basin into an important ecological barrier and economic zone in China by taking care of the protection and not the development.The Yellow River is our mother river,and ecological environment protection is the focus of the Yellow River protection.The Weihe River is the largest tributary of the Yellow River.The study of water resources carrying capacity in Guanzhong area of the Weihe River Basin is helpful to practice the governance idea of"jointly grasping the great protection and jointly promoting the great governance"in the Yellow River Basin,and to construct a new situation of"promoting development in protection and promoting protection in development".Based on the idea of"analyzing the relationship between systems-building an index system-selecting evaluation methods-diagnosing obstacle factors-optimizing the carrying capacity",study on water resources carrying capacity and optimization and enhancement in the Guanzhong area of the Weihe River basin using entropy power method,improved hierarchical analysis method,as well as TOPSIS model,barrier degree model,and interval multi-objective planning model.The main contents and research results of this paper are as follows:(1)Study on water resources carrying capacity based on the improved TOPSIS model.From the time dimension,the overall water resources carrying capacity of the study area from 2012 to 2021 shows an upward trend;among them,the water resources carrying capacity of Weinan City has increased the most,with the closeness increasing from 0.332 to 0.760,a cumulative increase of 1.29 times;Baoji City has increased the least,with a ten-year increase of 49%.From the spatial dimension,the overall water resources carrying capacity is weak,and no city can reach the bearable state(Grade I),with obvious spatial differences;the ecological environment water consumption rate and water production modulus are the main obstacle factors for the improvement of water resources carrying capacity in the region,and the water ecology and water resources subsystem have greater constraints on the improvement of water resources carrying capacity.(2)Study on water resources carrying capacity based on"four water four fixed".Through the analysis of water resources carrying capacity of"determining people by water",from 2012 to 2021,the water resources carrying population of Xi’an,Tongchuan,Baoji,Xianyang and Weinan are 932-1092 million,61-69 million,334-418 million,314-463 million and 344-422 million respectively.Except for Baoji,the current population of all four cities is larger than the population that can be carried by water resources;through the analysis of water resources carrying capacity of"determining production by water",under the condition of fine management,that is,under the premise of ideal industrial added value water consumption of10000 yuan,the industrial added value carried by water resources in Tongchuan City,Baoji City,and Xianyang City is 11.6-20.7 billion yuan,72.8-107.1 billion yuan,and 58.4-109.9billion yuan,respectively.The current industrial added value is lower than the ideal industrial added value,and there is a significant gap between it and the ideal industrial added value,and the carrying state of"water production"is poor;through the analysis of water resources carrying capacity of"determining cultivated land by water",the highest upper limit value of cultivated land carrying capacity in Baoji City in 2017 was 3.560 million mu,and the lowest lower limit value of cultivated land carrying capacity in 2021 was 1.915 million mu,which were far lower than the current cultivated land area and were seriously overloaded;through the analysis of water resources carrying capacity of"determining city by water",the upper limit of urban construction land that can be carried by water resources in Xi’an is 840-1013 km~2,the lower limit is 771-930 km~2,and it is expected to reach the upper limit of construction land carried by water resources in 2025-2027.(3)Optimization and improvement of water resources carrying capacity based on interval multi-objective programming model.Based on the interval uncertainty in the water resources system,the interval multi-objective planning model is applied to the study of water resources carrying capacity enhancement of the Baoji section of the Weihe River with economic and ecological benefits as the objectives and ecological baseflow,food production safety and water availability as the constraints.The results show that:the multi-objective model can balance the water use competition between different objectives;the industrial and ecological sectors have high economic added value,and the traditional agricultural sector has a low economic benefit coefficient.The model optimization result adjusts the industrial structure and improves the proportion of water consumption in the industrial and ecological sectors;the economic benefits of the model are increased by 4.51%and COD emissions are reduced by 4.82%compared with the current situation,and the carrying capacity of water resources is improved to a certain extent.(4)Based on the above research understanding,in order to improve the water resources carrying capacity,corresponding suggestions are made from four subsystems:water resources,social economy,water environment and water ecology.From the water resources subsystem,we should implement the requirements of the strictest water resources management system,promote water-saving and drought-resistant technologies for crops,and improve water use efficiency;from the socio-economic subsystem,we should promote the upgrading of industrial structure and strictly control the development of high water-consuming industries;from the water environment subsystem,we should reduce COD emissions,improve sewage treatment capacity,and accelerate the realization of sewage resource utilization;from the water environment subsystem,we should increase the urban greening area,improve the proportion of water used for ecological environment,and coordinate the economic development and ecological environmental protection of the region from an overall perspective.