| Water,energy and food are the three strategic supporting elements for the sustainable development of national economy,and the important material basis for human survival,economic development and social progress.In recent years,under the background of climate change and rapid economic and social development,water resource shortage areas are often faced with the objective reality that energy and food production are increasingly competitive in water resources utilization.Yulin is located in the northern margin of the Loess Plateau.It is an important energy base in China and one of the key characteristic agricultural bases in Shaanxi Province.At the same time,it is faced with serious water shortage.It is of great significance to realize the coordinated security of water,energy and food in this region for the healthy development of the local economy and the guarantee of national energy security,food security and water security.This paper explores the theory and method of water resources optimal allocation in water-deficient areas from the perspective of water-energy-food nexus,analyzes the current situation of water resources development and utilization in Yulin,and forecasts the supply and demand of water resources in the future level year(2025).Considering the relationship between water,energy and food,the optimization model of energy and food production industrial structure was constructed under the suitable water condition,and the scale and layout scheme of suitable water industry in Yulin was put forward.The water resource allocation scheme of Yulin based on food-energy industrial structure adjustment by using WAS model.The main conclusions of this paper are as follows:(1)This paper analyzes the current situation of water resources utilization in Yulin from two dimensions of physical water and virtual water and predicts the water demand and available water under different incoming water frequency in 2025.It is found that in the dimension of physical water,the industrial,living and ecological water in Yulin increased significantly.In the dimension of virtual water,Yulin is the net virtual water output area,and the virtual water outflow embedded in food and energy products further aggravates the pressure of water resources in Yulin.At the same time,this paper takes 2018 as the current level year and predicts according to the regional development planning that the total water demand in the normal inflow year of Yulin in 2025 will be 1.42 billion m3(P=50%),the available water supply will be 1.40 billion m3,and the city's water shortage will be 16.21 million m3,with a water shortage rate of 1.14%.In the year of drought,the available water supply in Yulin will be 1.32 billion m3 in 2025,the total water demand will be 1.61 billion m3,the total water shortage will increase to 292.17 million m3,and the water shortage rate will be 18.12%.The comparison of water supply and demand shows that Yulin will be short of water in the future.(2)In this paper,under the suitable water condition a multi-objective optimization model of energy and food production industrial structure in Yulin city is constructed,and the model is solved based on multi-objective particle swarm optimization algorithm.The model takes the maximum economic benefit,the minimum environmental impact and the maximum social benefit as the objective function,and takes the water supply security,food security and the maximum production scale of energy as the constraints.The results showed that in the 50%hydrological year,the food planting area and energy planning output were higher than the current year,and the economic benefits and job opportunities of food and energy production in Yulin were improved.Under the 75%guarantee rate,the available water resource constraints lead to the reduction of food planting area and energy production has been reduced by 9.95%.The water efficiency has been greatly improved.It can be seen that the optimization of industrial structure is helpful to improve the economic benefit and water saving potential of Yulin.(3)The optimal allocation scheme of water resources in Yulin was put forward by using WAS model.In this paper,the WAS model of Yulin was constructed and verified based on the actual water supply data of Yulin in 2018.The results show that the relative error rate of the model is only 0.66%,and the simulation effect of the water resource allocation model is good and has a certain credibility.Based on this model,this paper simulated that the total water supply of Yulin in 2025 will be 1.37 billion m3 and 1.29 billion m3 respectively under the inflow frequency of 50%and 75%.From the perspective of water consumption,in the future 50%hydrological year of 2025,the proportion of water used in industrial production will exceed that of agricultural production,accounting for nearly half of the total water consumption in Yulin.In dry years,due to the limitation of available water,the water consumption of energy and food production is 153.64 million m3,and 188.48 million m3 under the suitable for water production structure of energy and food.Compared with normal year,the annual water consumption decreased by 34.94%and 34.34%respectively.(4)The regional water resources security degree before and after industrial structure optimization were compared and analyzed.In the years with 50%and 75%water inflow,the water shortage rate of Yulin was 1.14%and 18.12%respectively before the optimization of grain planting area and energy output.After optimization,the total water shortage rate of the whole city reached 100%,and the water shortage rate of all counties and districts showed a downward trend.The water resource optimization scheme from the perspective of water-energy-food nexus can significantly reduce the water shortage rate of each county and district in Yulin and improve the water security level of the whole city. |
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