| Water is the foundation of ecology and the basic element of urban systems.As a typical water-deficient city in north China,the contradiction between supply and demand of water resources in Taiyuan is increasingly prominent in the process of economic development and urbanization.In recent years,the rapid growth of water consumption in urban ecological environment and the unreasonable allocation of water resources make the water shortage more serious.On the basis of summarizing the resources,environment,society and economy of Taiyuan,this paper analyzed the current situation of water resources development and utilization,and summarized the outstanding problems existing in the development and utilization of water resources.Faced with the rapid growth of ecological environment water consumption,the urban area of Taiyuan City was taken as the object to carry out research on the connotation,classification and accounting of ecological environment water demand.The current water demand of rivers,lakes,vegetation and clean environment in urban areas was calculated,revealing the prominent contradiction between the increase of water demand for urban ecological environment and the actual shortage of water supply.Based on the constraints of urban water resources,this paper discussed the theory of ecological environment water use limitation,and put forward suggestions for strengthening the demand-side management of urban ecological environment water use.Under the condition of urban ecological environment water consumption constraint,this study predicted the water supply and demand of various water sources and departments in 2025,established a multi-objective optimal allocation model of water resources,calculated best allocation scheme of comprehensive benefit,and put forward the corresponding measures to provide scientific basis for Taiyuan water resources management.The research results mainly reflected the following aspects:(1)Based on the analysis of precipitation and runoff data of Taiyuan urban long series,it was found that there was a great gap in annual distribution of precipitation,accounting for59%in summer,and annual precipitation increased about 23.5 mm every 5 years.The annual runoff was unevenly distributed,accounting for 39%in summer.The annual runoff decreased year by year,about 1.2×10~9 m~3 every 5 years.According to the analysis of urban water supply and consumption from 2015 to 2019,urban water supply and consumption increased year by year,and ecological environment water consumption increased the fastest.At the same time,the field investigation found that the water for the ecological environment was insufficient,the rivers stopped flowing,the water quality of the lakes deteriorated,and the vegetation growth conditions were not good.It could be seen that there is an imbalance between the supply and demand of water for the ecological environment in Taiyuan City.(2)The connotation and components of urban ecological environment water demand were discussed.According to the characteristics of Taiyuan City,four types of ecological environment water demand calculation methods of rivers,lakes,vegetation and urban cleaning were established by using the functional method.The calculated annual water requirements of the four types of ecological environment in Taiyuan City were 1.59×10~8 m~3,3.46×10~7 m~3,2.27×10~7 m~3 and 6.90×10~6 m~3 respectively.According to the analysis of supply and demand,the actual water supply was far from meeting the water demand,and the annual water shortage in the ecological environment reached 8.07×10~7 m~3.Based on the constraints of urban water resources,this paper discussed the constraint theory of urban ecological environment water use,and put forward suggestions on strengthening the demand-side management of ecological environment water.(3)This paper predicted and analyzed the water supply and demand in the planned horizontal year(2025)of downtown Taiyuan.With the expansion of the scale of Yellow River diversion in the urban area,the total water supply in the planned horizontal annual can reach7.28×10~8 m~3.Under the condition of fully considering the water constraint,the ecological and environmental water demand was predicted in this study,and the ecological and environmental water demand tended to be reasonable by adjusting the influencing factors such as water surface rate and greening growth rate.According to the planning and policy document,the total water demand at the urban planned horizontal annual was 7.71×10~8 m~3.By increasing supply and reducing demand,the urban water shortage was 4.26×10~7 m~3,and the water shortage rate could be controlled at 5.5%.On this basis,combined with the idea of water resources allocation,the optimal allocation model of water resources of multi-objective,multi-source and multi-department was established.Fgoalattain function of MATLAB software was used to calculate the optimal allocation scheme of water resources with the comprehensive benefits of ecological environment,social and economic goals.Under this scheme,the amount of water allocated could meet the guarantee rate of each department.Finally,some guarantee measures and water resource utilization suggestions were put forward for the configuration plan from the aspects of water supply and water demand,so as to provide management basis for the sustainable utilization of water resources in Taiyuan City. |
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