Spatial Pattern Optimization Of Green Infrastructure In Pazhou Island Of Guangzhou Based On Water Regulation Services Supply And Demand

Under the background of climate change and urban expansion,urban stormwater disasters occur frequently.Green infrastructure(GI)can provide water regulation services in cities,but the lack of meso-scale spatial pattern optimization procedures has led to a widespread mismatch of service supply and demand.The meso-scale GI spatial pattern planning methods based on the comprehensive perspective of natural processes,land use and control objectives is worth exploring.When ecosystem service supply and demand theory is applied to hydrological research,it can accurately reveal the process and spatial relationship of GI’s regulating effect through the dynamic process of supply and demand.So it has the potential to become an effective tool to guide GI’s planning.Comprehensive research on the supply and demand of water regulation services needs to be in-depth.This paper introduced the theory of water regulation service supply and demand into the study of urban GI spatial pattern optimization,trying to build an meso-scale GI’s stormwater safety pattern optimization method considering the "ecology-society-hydrological system" comprehensively,which is of great significance to improve the mismatch of supply and demand of urban GI water regulation service and alleviate urban stormwater disasters.The theoretical research part analyzed the GI’s water regulation service mechanism,the connotation of pattern optimization,and the theoretical framework of service supply and demand dynamics,to interprets the "service-pattern" response mechanism as "numerical relationship of supply and demand response scale","spatial relationship of supply and demand response layout ",and "supply flow response structure" and "comprehensive supply-demand relationship response type",and constructed the whole process optimization path of "Hydrological environment analysis and problem feature identification→GI landscape pattern characteristic analysis→GI water regulation service supply and demand measurement and mapping→GI pattern optimization and multi-scenario comparison and control ".The empirical research part took Pazhou Island in Guangzhou as an example to verify the feasibility of the path.The geographical location and hydrological environment determine the peculiarities of the stormwater problem in Pazhou Island.The SWMM model combined with superposition method is the most suitable method for measuring the supply and demand of islands.The SWMM runoff process and runoff control indicators of sponge city are used in the numerical calculation of supply and demand,and the service demand level is corrected by combining 7 evaluation indicators in three aspects: hazard,disaster-pregnant environment and disaster-bearing body,aiming to reveal the relationship between values and the spatial distribution of GI’s water regulation services supply and demand in Pazhou Island before and after the plan.GI’s spatial pattern analysis and water regulation services supply and demand measurement show that the current GI distribution is concentrated,and the spatial differentiation of the supply level is obvious.In comparison,The GI after planning is evenly dispersed,the supply value increases and the supply spatial differentiation declines.The demand level decreases but the demand spatial differentiation intensifies.In general,the situation of short supply and spatial mismatch between supply and demand both appear before and after the planning.,although there is a slight improvement after the planning,the spatial differentiation situation intensifies.By summarizing the stormwater problem,GI pattern characteristics and supply and demand measurement results.it can be obtained that the characteristics of stormwater vulnerability in Pazhou Island are system isolation,spatial differentiation,and land contradiction.Aiming at the goal of supply and demand balance,"structure-scale-type-layout" strategy are combined to construct the optimization plan of Pazhou Island.GI network structure are constructed based on supply and demand units,GI implementation scale are evaluated based on supply and demand difference,GI’s type are determined based on land use characteristics,and GI priority layout are determined based on the spatial differentiation of supply and demand.The paper also discussed the practical application of the optimization plan briefly in the end.Scenario comparison results showed that the optimization plan generally achieves the goals,which improved that the optimization path and strategy are effective and feasible,and the method can provide a reference for the optimization of stormwater safety patterns in other meso-scale urban areas.