Research On Supply And Demand Evaluation Of Water-Related Ecosystem Services And Layout Optimization In Urban Green Spaces

At present,domestic cities are generally facing complex water ecology and environmental problems,and the conflict between people and the environment is prominent.Sponge city construction focuses on using the natural urban environment to cope with urban water environment problems.As an important part of the urban natural ecosystem and public open space,urban green space plays an important ecosystem service function.Urban green space is an important ecological space to ensure the safety of the urban water environment and is the main living space for urban residents to benefit from the natural environment.Therefore,from the perspective of water-related ecosystem services,identifying the spatial pattern between urban green space supply and demand,and optimizing the spatial distribution of urban green space is conducive to alleviating urban water problems and harmonizing the contradiction between people and the environment.This study constructs an evaluation system for the supply and demand of water-related ecosystem services of urban green spaces.Using Arc GIS,In VEST,Python,and ROST Content Mining,the quantitative assessment of supply and demand,spatial mapping,and spatial autocorrelation analysis were conducted for six types of water-related ecosystem services in urban green spaces:water harvesting,stormwater regulation,water purification,habitat quality,recreation,and history,to identify the spatial pattern for each type of services.The Z-score standardization and four-quadrant approach were used to identify the spatial relationships between supply and demand.Subsequently,the landscape pattern index of urban green space was calculated quantitatively from the type level and landscape level.Urban green space landscape pattern characteristics of different supply and demand spaces were analyzed to determine the urban green space types and landscape pattern indicators that affect the supply and demand relationship.Finally,urban green space optimization directions are proposed,and specific spatial layout optimization was carried out for park green space,subsidiary green space,and regional green space.Urban green space water ecosystem service optimization strategies were proposed from macro and meso perspectives.The study found that:(1)There is significant spatial heterogeneity in the supply and demand of urban green spaces.The spaces with high supply are concentrated in the old city and the north and south edges of the study area.In addition,the spaces with high supply of water harvesting,stormwater regulation and water purification services are distributed in the green spaces on the east and west edges of the study area.Habitat quality services are distributed along the Xiaoqing River,and leisure services are distributed along the north-south urban rivers.The demand generally shows the distribution characteristics of"the central part is higher than the edge,the north is higher than the south,and the east is higher than the west".(2)Regional green spaces play a vital role in water-related ecosystem services.Subsidiary green spaces and protective green spaces focus on improving the urban water environment.Park green spaces focus on leisure and history services.(3)The relationship between supply and demand is mostly inefficient and needs to be strengthened.The efficient matching of habitat quality services is concentrated in the green space in the eastern part of the study area.The spatial distribution of supply surpluses are located in the green space around the study area.The spaces for efficient matching of leisure and history services are located in the old city and Huashan Lake Park.In addition,the space for efficient matching and surplus supply of leisure services is distributed along the north-south urban river.The service weak spaces of the six types of services are concentrated in the middle of the study area,and the inefficient matching spaces are widely distributed around.(4)The direction in efficient matching and surplus supply space is to maintain the status quo and ecological protection respectively.In inefficiently matched and weakly served spaces,the layout of regional,subsidiary and park green spaces is adjusted.After optimization,the area of urban green space increased by 63.37km~2 and the green space coverage increased by 10.4%.