Abstract:

Water resources are the indispensable factors to the development of human society and natural environment.The maximum capacity of water resources system to support that development is called Water Resources Carrying Capacity (WRCC).A reasonable evaluation of WRCC has a guiding significance to the sustainable exploitation of water resources and the development planning of society and economy.There are many ways to assess the WRCC of a basin or district.They are generally based on the traditional hydrological cycle consisting of evaporation,transportation,precipitation,and transpiration.Dualistic water cycle model,as a new coming view of hydrologic cycle,divides however the cycle into natural and social parts.The natural part refers to the traditional hydrological cycle,while the social part includes the processes of watertaking,wateruse,and drainage.Therefore,the interaction between human society and water resources system is embodied in one system,in which the interference between them can be studied in a more effectively way.Based on the theory of “dualistic water cycle model”,a concept of “carrying unit” is put forward.Carrying unit refers to a segment of a river,where water can be taken to supply to a district and receive the drainage from that district.With the concept of carrying unit,WRCC would be realized through a carrying unit to support the development of society and natural environment.The carrying unit has a property of system response,meaning that water resources will change in quality,quantity,and power potential after it flows through a carrying unit and experiences the external cycle of society and the internal cycle of nature system,and then its carrying capacity will change accordingly.Carrying unit,therefore,reflects the relationship between upstream and downstream of a river,and the coupling among human society,water resources system,and natural environment.Afterwards,a new approach to assess WRCC is provided based on carrying unit,and a new index system including water quality,quantity and power potential is developed,too.In the end,a case study on Kunming City is provided to verify the effectiveness of this method