Study On The Change Of Water Resources Carrying Capacity Driven By Climate Change And Economic Development In Yunnan Province

Climate change and human activities have changed the watershed hydrological recycle processes,affecting the structure and function of the water resources system.These effects have led to the many problems such as the regional unbalance of supply-demand of water resources,as well as the frequent occurrence of drought and flood,making human face a challenge of the utilization of water resources.Water resources carrying capacity is regarded as a basic measure of regional water resources security,reflecting the ability of water resources systems to support the socio-economic and ecological harmonious development.The assessment of water resources carrying capacity is an important basis for the effective use of water resources,playing an important role in addressing climate change,improving water use efficiency and promoting social and economic sustainable development.In this study,we firstly analyze the variations characteristics of precipitation,runoff and water resources by meteorological data(1961-2015),runoff data,water resources statistics data(2000-2015)in Yunnan Province.Then,a comprehensive assessment model ofwater resources carrying capacity is established to study the spatial and temporal changes characteristics of water resources carrying capacity from 2000 to 2015_Finally,combined with the climate change scenarios,economic development scenarios and the Central Yunnan Diversion Project,we get the change characteristics of water resources carrying capacity in Yunnan during the period of 2020,2025 and 2030.The main conclusions are as follows:(1)The annual averaged precipitation in Yunnan Province decreases significantly from 1961 to 2015(p<0.1)at a rate of-15.2 mm/10a.Especially in the eastern region,the decreasing trend is more obvious.The annual runoff of the Pearl River,Yuanjiang River and Lancang River Basin shows a decreasing trend(p<0.05),and the change trend of the annual runoff in Nujiang River Basin is not significant.There is an increasingly severe situation in which the water consumption is increasing,while the total water resource is gradually decreasing from 2000 to 2015.Additionally,the water supply capacity gets a promotion for the increment of reservoir quantity and storage(2)The water resources,social,economic and ecological environment evaluation indicators are selected,and the evaluation model of water resources carrying capacity is established,considering the economic pressure,population pressure,carrying pressure and coordination level.The carrying capacity and utilization level of water resources in Yunnan from 2000 to 2015 are evaluated,and the spatial-temporal distributions characteristics are discussed.The results show that,spatially,the distr:ibution of water resources does not match the layout of economic decelopment and population.The Central regions are close to overloaded areas or lightly overloaded area,which is due to a number of population and relatively developed economy,but less water resources.Temporally,with the rapid development of population and economic,the pressure of regional water resources carrying capacity gradually increases.For example,Zhaotong city,which is located in the northeastern part of Yunnan,turnes into the verge of the overloaded area,which used to be the suitable area of water carrying capacity.(3)The variations characteristics of climate,population and economy in Yunnan from 2015 to 2030 are analyzed by the Representative Concentration Pathways(RCP4.5 and RCP8.5)data under the Regional Climate Model version 4 and Shared Socioeconomic Pathways data released by the Intergovernmental Panel on Climate Change.The results show that the annual precipitation in Yunnan shows different trends under the two climate change scenarios.Under the RCP 4.5 scenario,the annual precipitation shows an increasing trend at a rate of2.8 mm/a.Under the RCP 8.5 scenario,the annual precipitation shows a decreasing trend at a rate of-9.4 mm/a.The population and GDP of Yunnan generally show an increasing trend under the three social-economic development scenarios.Under the SSP3 path,the regional competition is fierce with the largest population and the fastest growth rate.Under the SSP1 path,the economy achieves sustainable development with the largest GDP and the fastest growth speed.(4)Based on the evaluation model of water resources carrying capacity,the dynamic changes of water resources carrying capacity are analyzed comparatively in 2020,2025 and 2030 under different scenarios by the data of RegCM4 and SSPs,as well as the planning data of the Central Yunnan Diversion Project.The results show that under the three scenarios of RCP 4.5_SSP1,RCP 8.5_SSP3,and RCP 8.5_SSP5,at temporal scale,the carrying pressure of regional water resources has obviously increased from 2020 to 2025,and is alleviated to some extent from 2025 to 2030,such as Chuxiong city,which transforms to the edge of the overloaded area from the lightly overloaded area.At spatial scale,the carrying pressure of regional water resources is the largest under the scenario of RCP 8.5 SSP3 in 2020,2025 and 2030.Especially Honghe,Baoshan and Lincang city have mild uncoordinated phenomenon in water resources use,which belong to the edge ofthe overloaded areas with considerable carrying pressure of water resources.While these areas have coordinative development of economy and water resources utilization under the scenarios of RCP 4.5_SSP1 and RCP 8.5_SSP5,which are the suitable areas of water resources carrying cpacity.