中国地级以上城市公园绿地服务水平评估:数据、模型和方法

现有城市公园绿地服务的评估常以给定的城市空间范围和公园绿地为前提,评估对象及其空间范围具有较大随意性,致使很难根据评估结果判断城市公园绿地的空间配置是否合理,或对不同城市进行比较。本文对城市公园绿地服务水平评估的数据、模型和方法进行了梳理,从公园绿地的类别、等级、服务范围和可选择性等要素着眼,提出了以城市建成区内居民至周边公园绿地的可达性为核心的评估指标和模型方法。运用开源空间数据和Densi-Graph分析方法,解决了城市公园绿地空间数据的提取、城市建成区范围的界定、指标构建等关键技术问题,使城市公园绿地的评估获得了客观性、统一性和可比性的保障。对全国273个地级的评估结果表明,我国地级市公园绿地服务覆盖率平均值达到64.8%,尚有超过两成的城市公园绿地服务覆盖率不到50.0%,公园绿地服务水平与现行国家标准之间尚有差距。公园绿地服务水平存在明显的区域差距,服务水平较高的城市显著集中于特大城市、东部沿海发达地区和东北地区,同时,与城市人口规模相对应呈现出S型曲线上升趋势。为避免区域发展的不协调,应增加对中小城市和中西部地区城市绿地公共服务的投入。

Evaluation of the service of parks in Chinese urban areas

Previous evaluation of the service of urban parks has always based on a given city spatial range and given green parks. This means that the evaluation subject and the spatial range for evaluation is often chosen randomly, which makes it very hard to decide whether the spatial distribution of urban green parks is appropriate or not on the basis of the evaluation results, and also it is hard to make comparisons between different cities. This paper collected and studied the data, model and method on the evaluation of the service level of urban green parks, and researched from the perspective of the category, degree, service range and the availability of alternative choices of urban green parks, and based on the research, an evaluation indicator system and model is proposed which is centered on the accessibility of the residents living in urban built-up areas to surrounding green spaces. This paper also employs open source POI (point of interest) and the analysis method of Densi-Graph, which provides solution to the extraction of spatial data of urban green parks, the definition of the urban built-up range, the construction of specific indicators and other key technical problems. In this way, the objectivity and integrity of the evaluation of city green parks is guaranteed, and the evaluation results of different cities can also be compared. The evaluation results for 273 prefecture-level cities in China, demonstrate that the average service coverage rate of the urban green parks in prefecture-level cities in China reaches 64.8%. And there are still more than 20% of prefecture-level cities which have a service coverage rate less than 50.0%, indicating that there is a gap between the actual service level of urban green parks and the current national standards. In addition, there are significant differences of service level of urban city parks between different regions. Cities with higher service level are often megacities with population over one million and cities in developed eastern and northeastern China. At the same time, the service level is co-related with the population scale of a city in an S-shaped curve. In order to avoid incoordination of regional development, it is suggested that more resource should be input to the public service of urban green parks in middle and small cities and cities in central and western China.