Study On Planning Of Multi-scale Green Infrastructure’s Network Structure

As a smart development strategy under rapid urbanization conditions in the 21st century, green infrastructure (GI), due to its connotation inclusiveness, composite function and scalability, exerts more powerful natural protection function and social service function than other development strategies and gradually attracts wide attention from scholars. Current GI studies focused on the connotation and single-scale planning, but the integrated multi-scale planning was seldom reported.This study discussed the planning methods of multi-scale green infrastructure network structure and provided the empirical study results of the Yangtze River Delta Region in three scales including region, city, and central urban district as follows:Firstly, a new planning process of multi-scale (region, city, and central urban district) green infrastructure space structure was systematically sorted out. The planning process involved determination of planning goals, screening planning methods and tools, evaluation of GI elements and the fusion of planning results of various planning levels. The study results indicated that various planning levels required different planning goals, methods and tools. Planning methods and tools of various levels should be screened based on the planning goals and the data characteristics of the study area. The high-level planning results might be used to guide the low-level planning, whereas the low-level planning results might provide supports and demand suggestions for the high-level planning.Secondly, the network structure of green infrastructure in the Yangtze River Delta Region was established. The network structure was composed of 135 hubs and 19 corridors. These hubs included Yangtze Estuary Wetlands in Shanghai, Taihu Lake Wetlands in Jiangsu Province, and Gaoyou Lake Wetland Nature Reserves, Eastern Tianmu Mountain Nature Reserves, Kuocang Mountain Nature Reserves in Zhejiang Province. The corridors included the main channel of the Yangtze River, the Taihu Lake-Dianshan Lake-Huangpu River corridor, and the forest corridors in eastern Zhejiang Province. Among these hubs and corridors, the Yangtze River Estuary Wetlands and the Huangpu River-Dianshan River corridor had the important ecological conservation values at the regional scale and were also seriously threatened by urban development. Therefore, particular attention should be paid to coordinate conservation and development in the two regions.Thirdly, the green infrastructure network structure of Shanghai was established. The Shanghai land conservation network included 44 biological conservation centers and five important ecological corridors. Moreover,7 Shanghai land open space systems were established and the three-circle urban land open space network was planned. Shanghai green infrastructure network was obtained through coupling land conservation network with land open space network. The coupling results showed that the land conservation network did not completely coincide with open space conservation network. The two networks coincided with each other in only three sections:the east-west section of Hujin-Shenhai Highway, the southern section of the outer ring highway and the north-south section of Hulu Highway. In the three sections, the planning should avoid the interference between ecological conservation land and construction land.Fourthly, from the perspective of spatial equity of residents, green infrastructure elements (GI elements) and spatial distribution of the central district of Shanghai were quantitatively evaluated. The evaluation results indicated that the residents in the central district of Shanghai showed the large difference in spatial equity of park utilization.The spatial equity of park utilization of the residents in Puxi District, which was a densely populated old district, was significantly lower than that in the Pudong District. Existing park layout and number in the central district of Shanghai could not meet the demands of residents. Therefore, it is necessary to increase large-scale open space in the city level.This study discussed planning method and tools of green infrastructure network structure in three scales and proposed a fused "top-down" and "bottom-up" planning framework of the multi-scale green infrastructure network structure. The study provides the theoretical basis for the planning practices of green infrastructure in China.