关键词: 城市绿地, 绿地供需匹配, 两步移动搜索法, 空间启发式算法, 绿地布局优化

Abstract:

Since urban green space (UGS) can provide significant ecological and social benefits, it is considered to have important impacts on urban environment and inhabitants’ quality of life. Thus, UGS allocation has become the focus of urban planning and the main avenues for low-carbon city and sponge city building. However, the population and green space data used by existing studies for UGS allocation were not adequately accurate, and the results were course with limited referential value. In addition, existing studies rarely go further step to study layout optimization of the newly increased green space. The main work of this research is to evaluate the supply and demand for UGS at community level, then proposing an optimization approach to promote the level of the green deficit communities to get a more equal green space layout. Firstly, Google image with resolution of 0.25 m was used to get different green land distributions, and Web Crawling method was employed to obtain population of communities from the real estate transaction websites such as Anjuke, Fang.com and Tencent's property. Secondly, the UGS supply of 520 communities was evaluated with the two-step floating catchment area method, and then the supply-demand match and its spatial variation were analyzed according to relevant demand standards. Lastly, in order to minimize the number of green deficit communities, a spatial heuristic model was established. With this model, the inefficient industrial parcels with proper quantity and location were selected to be converted into green space to generate optimized green space layout. The results are as follows: 39% communities has a green space supply less than the planning standard (20.1 m ²). Thus, the supply-demand correspondence of green space in central urban area of Xuzhou is not equal. While a large proportion of supply saturated communities are located in Yunlong Lake and Quanshan Park districts, most supply deficit communities are located at old urban areas and along Huaihai Road down to Jinshanqiao district. Since the green space distribution should be consistent with the population spatial distribution, it is necessary to configure large and medium-sized green parks in high-rise residential cluster areas rather than allocating most of the land to commercial and residential uses for “land finance” purpose. As a result of the UGS layout optimization with spatial heuristic algorithm, green space supply deficit communities decreased by 37 with the cost of 431 hm ² inefficiency industrial plots being converted into green land. This study can provide scientific reference and technical support for UGS allocation during urban planning. It can also provide reference for the choices of residential communities for home buyers from the perspective of accessible UGS quantity.

Key words: urban green space, greenland supply-demand match, two-step floating catchment area method, spatial heuristic algorithm, green space layout optimization