| Under the dual pressures of rapid urban development and climate change,the ecological risks faced by urbanized areas are increasing due to the weakening of ecosystem services and the reduction of green space.Among many ecological problems,urban heat island has become one of the common problems faced by cities,which seriously threatens the health of residents.As an important means to provide ecosystem services in cities,green space plays an important role in reducing urban surface temperature and mitigating heat island.With the increasing demand for urban cooling,improving the cooling efficiency of existing green spaces has become increasingly urgent.Therefore,it is of great significance for green space planning to identify Green Infrastructure Combination Patterns with efficient cooling in different built environments.Starting from the influencing factors of urban thermal environment and the cooling mechanism of green infrastructure,this thesis constructed a research paradigm of "Mixed Land Use Patterns--Green Infrastructure Combination Patterns--Efficient Cooling Combination Patterns" and an empirical technical framework of "Combination patterns recognition--Marginal effect analysis--Target scenario simulation--Efficient mode summary".Aiming at the problems of unbalanced urban green space structure and insufficient service capacity,this thesis selected typical districts of Jinan old city to conduct empirical research,analyzed the structural characteristics of efficient cooling green infrastructure,and summarized the multi-dimensional and multi-level adaptive regulation approaches.Firstly,on the basis of summarizing the influencing factors of thermal environment and urban spatial characteristics,four indicators are selected to describe the spatial characteristics of the study area.The K-medoids clustering algorithm and the relative temperature difference method were used to divide the Mixed Land Use Patterns and the cold and hot island space in the study area.Then,the thermal environmental effects of various mixed land use models were identified according to the marginal effect curve were identified according to the marginal effect curve.There are 10 Mixed Land Use Patterns in total.Comparing their spatial characteristics,it was found that the ratio of blue-green space coverage and building height are the key factors affecting the thermal environment.Secondly,based on the cooling pathways and influencing factors of green infrastructure,5 Green Infrastructure Combination Patterns are divided.Next,the cooling effect was analyzed using linear regression.The study found that the cooling effect of the GICP is related to the proportion of canopy,and its optimal value is 50%-79%.Thirdly,with the support of ENVI-met,nine green spaces and communities with poor cooling effect in the study area were selected as examples to simulate the cooling effect under different scenarios.According to the simulation results,indicators such as green coverage rate and three-dimensional green amount are selected to summarize the spatial characteristics of the high-efficiency cooling combination mode,which provides a theoretical reference for green space system planning.Finally,based on the theoretical results,the high-precision climate adaptation regulation approaches were summarized,and the green space optimization strategies of typical districts of Jinan old city were proposed from three scales of block,patch and quadrat.This thesis innovate in terms of research paradigms and technical methods.It is concluded that adjusting the proportion of blue and green space coverage and controlling the scale of green space are important means to improve the comprehensive benefits of urban space,and optimizing the proportion and spatial layout of green infrastructure is an important way to ensure the efficiency of green space cooling.It provides theoretical basis and practical reference for the improvement and perfection of urban green space system planning of typical districts of Jinan old city. |
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