A Study On Green Infrastructure Functional Assessment And Its Network Planning In Zhengzhou City

With the accelerated urbanisation process,it has resulted in cities struggling to meet the needs and level of well-being of human beings for a better life.The increase in urban population has been accompanied by the expansion of land for urban construction,and urban problems such as urban storm water flooding,reduced biodiversity,decreased air quality,increased biotoxicity and damage to the human habitat are frequent.Green Infrastructure(GI)can be effective in addressing these issues and GI has a number of roles to play in helping cities to live in harmony with people and the natural environment,improving urban ecosystems and enhancing the green image of cities.However,the current compression,weakening and imbalance of the GI space in the city have led to a gradual disfunctionalisation.Therefore,in this study,Zhengzhou City,with an area of 7580.80km~2,was used to assess the GI functions related to rainfall regulation,climate regulation,landscape recreation,air quality improvement,biodiversity conservation and social vulnerability reduction.The correlation analysis method and the Green Infrastructure Spatial Planning(GISP)model method were used to obtain the results of the overall GI function assessment in Zhengzhou City;on this basis,MSPA,landscape connectivity and circuit theory were combined to form GI centres,corridors and pinch points,and finally the GI network was constructed accordingly.The findings of this study are as follows:(1)The spatial distribution of the benefits of the six GI functions in Zhengzhou in the study showed significant differences.The five functions of rainfall regulation,climate regulation,landscape recreation,air quality improvement and biodiversity conservation are all generally higher in the western mountainous areas and lower in the eastern plains,while the social vulnerability reduction function is higher in the eastern urban areas and lower in the surrounding areas.The GI planning for the urban and suburban areas is the way to build a green city,as all the functions are weaker than the outer areas,except for the social vulnerability reduction function,which is slightly stronger.(2)In the correlation analysis of the GI functions,all the functions are highly significant,except for the correlation between the biodiversity conservation function and the social vulnerability reduction function,which is not significant.The results of the correlation analysis and the spatial clustering analysis together indicate that the planning of GI is more likely to bring about the common benefits of the five functions of rainfall regulation,climate regulation,landscape recreation,spatial quality improvement and biodiversity conservation,and that the maintenance and construction of these functions can be coordinated.The functions and benefits of GI in Zhengzhou City are generally low,and the current layout of GI shows that the GI functions are mainly high trade-off and low synergy,and the current layout of GI has more space for improvement,and in future GI planning,efforts should be made to gradually upgrade high trade-off areas to high synergy areas.(3)The morphological pattern analysis method and the landscape connectivity method identified 17 GI network centres in Zhengzhou,with a total area of 757.78km~2 of GI elements,and the GI network centre area is about 380.06km~2,accounting for 50.15%of the total GI area.7 of the 17 network centres are arable land,so Zhengzhou must combine the characteristics of the local area to improve the overall GI level.It is necessary to grasp the area of arable land,the time point and the buffer area that other vegetation acts as.In terms of the different functions of the corridors,a high level of GI in a given area can lead to a reduction in connectivity,and an increase in the overall level of GI can increase the number of corridors,their complexity and the connectivity between them.(4)Multiple demands should be taken into account in GI planning.The demands made by each stakeholder may affect the final planning outcome,and it is the duty and obligation of planning decision-makers to satisfy or balance different demands as far as possible.The composite function construction GI network approach adopted in this study can effectively deal with the above issues by linking the whole study area from point to line and from line to surface.The important nodes and corridors in the GI network are delineated to clarify the priorities in the planning process.Targeted painting strategies are then implemented in conjunction with the current state of the local environment.However,the urban GI network construction and planning process spans a long period of time and places high demands on the various management and construction components,so this study argues for improved cross-sectoral cooperation,enhanced public participation and rationalised decision making implementation strategies.