Study On Water Resources Carrying Capacity Of Super Metropolises

Water is essential natural resources and strategic economic resources,as well as one of the controlling factors of the environment.The development of more than half of the cities in China is constrained by the shortage of water resources.The problem of water shortage in the metropolises is especially serious.Water resources have become the main bottleneck that constrains the sustainable and healthy development of the capital economy and society,and it's also one of the decisive factors of carrying capacity of urban and rural development.Considering the key role that water played in Beijing's natural resources and carrying capacity,this research takes Beijing city as an example to study the water resources carrying capacity of metropolises,supporting the establishment of monitoring and early warning mechanism for resources and environment carrying capacity of large cities,and better serving the governments' decision-making.Thus it has important and urgent practical significance.On the basis of summarizing the current research status of water resources carrying capacity in China and abroad,this paper analyzes the main characteristics of the water resources system of the city,and defines the concept of water resources carrying capacity,as follows:In a certain development stage of the city,at the level of the sustainable utilization of water resources in certain(sustainable state)conditions,water resources carrying capacity is the population size(number)which can be sustainably supported by the water resources system of the city.Based on the definition,its implications are analyzed.Following the basic theories and methods of water resources sustainable evaluation system,this study introduced the analysis method(i.e.the weighted statistical index method),which was usually used in sustainable analysis of water resources and water supply,to the water resources carrying capacity research of large cities.Based on the characteristics of uncertainty and fluctuation in hydrological system,reliability,vulnerability,and resiliency indices are defined.The definition and calculation of resiliency index are further discussed.Water resources carrying capacity model framework,calculation method and basic steps for metropolises are issued and discussed,in which indicators are employed as little as possible to reflect the performance of the water resources system,so that the influence of complicated calculation of complex index system can be avoid,thus enhancing the understandability and operationalization.This study takes Beijing city as a case,based on the analysis of the water resources and water supply characteristics from 1956 ~2015.The reliability,vulnerability,and resiliency indices are calculated to analyze the changes of water resources sustainability index in different stages of sustainable states.The impacts of the South-to-North Water Diversion Project are discussed.Meanwhile,the average comprehensive domestic water consumption of Beijing is analyzed and predicted.On this basis,carried population under different sustainable conditions and different water use caps are calculated for the year 2020 and the year 2030,respectively.The recommended policies to the improvement of water resources carrying capacity are raised.