| Water resources play a very important role in human life and social development.With population expansion,urbanization and climate change,water pollution and water environment have become worse.The water crisis is spreading around the world.As a big developing country,it is significant for China to achieve the sustainable utilization of water resources,especially to deal with the water ecological problem at the basin scale.In this regard,the watershed ecological compensation mechanism,a win-win stratege for environment and economy,attracts many attentions from all fields.Some related practices have been carried out in China under the strong policies support and guidance.However,nearly all of these practices focus on water quality assessment at present,which ignore the important regulating effect on water environment provided by the watershed ecosystem itself.This is a huge loss for human society.Under this background,this study explored the watershed ecological compensation mechanism from the ecological perspective.The Erhai Lake Basin(ELB)was the study object because of its rich ecological functions,urgent water environmental problems and weak mechanism on ecological compensation.Firstly,the value of water resources in ELB was measured by emergy theory to present the natural resource attributes and socio-eocnomic utilities of different kinds of water resources.Secondly,the sustainable development trend of ELB was showed with the aid of emergy.And the key factors restricting the sustainable development were identified from the relationships between the whole system and sub-systems.Thirdly,this study combined emergy theory,InVEST model and GIS to illustrate the spatial and temporal trends of ecosystem services in ELB and their influence factors.Lastly,the ecological compensation mechanism of ELB for the improvement of ecosystem services was built based on the foregoing analyses.It will be an appropriate complement for the current water quality rescue operation in ELB so that the sustainable development could be realized in the near future.The key results of this study were listed below.(1)The emdollars of natural water,engineering water and polluted water were 0.65yuan/m~3?4.27 yuan/m~3 and 2.85 yuan/m~3,respectively.Therefore,the tap water value and sewage treatment price in ELB should be 4.92 yuan/m~3 and 2.85 yuan/m~3,respectively.The calculated water prices were higher than the current water fee in ELB.(2)The economy of ELB developed rapidly from 2000 to 2015,which brought severe environmental load.A new emergy sustainability indicator for basin scale,named ESIW,was proposed in order to assess the sustainable level on the small scale which couldn't figure out by traditional emergy indicators.The ESIW took contribution of water resources within the basin scale into consideration.And results showed that the development mode in ELB was unsustainable.One reason was the over-usage of non-renewable resources caused by cement industry,vehicle manufacturing industry,fertilizer application and energy consumption.Another reason was the excessive and inefficient utilization of water resources.(3)The ecosystem services in ELB were divided into three categories and nine kinds in this study.They were provisioning services including water supply,food production and raw materials supply,regulating services including carbon sequestration,climate regulation,water retention,water purification and soil conservation,and cultural service including tourism.During the period of 2000-2015,the total ecosystem services in ELB increased because that the increased amount of provisioning and cultural services were higher than the decreased amount of regulating services.However,the decline of regulating services,which was caused by natural geography,land use and land coverage and socio-economic factors,represented ecosystem destruction in ELB.(4)The main subject of ecological compensation in ELB should be local governments at all levels.In addition,local cement enterprises,the companies with high energy and water consumption and high pollution,the residents consuming excess water,and tourists should also be regarded as eco-compensation subjects.The eco-compensation objects are local government that promote eco-compensation policies,enterprises,farmers and residents that protect water environment following government,and other collective or individual whose interests are damaged by ecological management.The eco-compensation standard in ELB should be the increased value of regulating services from 2000 to 2015,which is 8.065 billion yuan.The eco-compensation standards of different land types were also provided in this study.Government compensation should be the main eco-compensation modes in ELB with market compensation as a supplement.Diversified eco-compensation methods,such as economic compensation,policy compensation and industrial compensation,are necessary to implement ecological compensation in ELB.(5)In order to realize the sustainable development in ELB,the most important thing is ecological environmental protection.The detailed suggestions include optimizing spatial distribution of ecosystems,improving watershed ecological compensation mechanism,and strictly controlling pollution.Besides,green economy transformation,technical innovation and social construction are effective measures to accelerate sustainable success.Besides,there are some limitations.For example,some Unit Emergy Values come from different areas which may cause uncertainty problems,and some ecosystem services may be not included.These are worth future work.Nevertheless,this study could enrich the theoretical exploration of watershed ecological compensation mechanism in China. |
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