Abstract:Integrated water environmental management has been world widely treated as a fundamental means to support sustainable watershed development. Ecosystem Services (ESs), which refer to the direct and indirect contributions of ecosystems to human well-being and subsistence, are important factors for water quality maintenance and improvement. With increasing attention paid to the spatial management and control, "zoning classification" based on the ecosystem characteristics has become an important content of integrated watershed management. Based on the relationships between ecosystem characteristics and water quality, four ecological features including soil type, land usage, normalized vegetation index and population density were selected for aquatic ecoregion zoning using canonical correspondence analysis (CCA). Combining the spatial distribution of ecological features, catchments and administrative management units, Zhejiang Province was divided into ten aquatic ecoregions and 510 water environmental control units through cluster analysis and spatial overlap. The ES value of each unit was evaluated with the method of equivalent factor. The results showed that in 2015, the total ES value in Zhejiang Province reached 512.37 billion RMB, and those of individual units ranged from 5.98 to 13.65 billion RMB. Four ES bundles were obtained by K-means clustering method, and the service types and spatial distribution characteristics of the bundles were analyzed. Subsequently, the relationships between water quality and ecosystem services were analyzed for each unit. The results showed that Bundle I covered most of the mountain and hilly areas mainly located in the west and southwest, accounting for 52.68% of the province's total area, while Bundle Ⅱ had the smallest area but a relatively high water occupation ratio, mainly covering the Qiandao Lake and the estuary of the Qiantang River. Bundle Ⅲ was distributed relatively scattered, mostly in hilly and plain areas, while Bundle Ⅳ was primarily distributed in plain areas where cities and towns were located. The dominant ESs varied significantly in different ES bundles. For example, ESs such as raw material production, soil conservation, biodiversity protection, gas regulation, and climate regulation dominated in the Bundle I, while the regulatory services were the dominant ESs in Bundle Ⅱ, including gas regulation, water regulation and waste treatment. Food production contributed significantly to both Bundles Ⅲ and Ⅳ. The results also indicated that the characteristics of water quality are closely related to the ecological service, i.e., the higher the ES value, the better the water quality. As a result, the units were classified into four types, including protection, maintenance, improvement and remediation according to the characteristics of the water quality of each ES bundle. The differentiated water quality control and improvement approaches were proposed for the units in the four types of ES bundle, to support the water eco-environment management of Zhejiang Province.