标度律视角的城市效能测度及中国城市多维要素效能分析

“城市标度律”（urban scaling laws）揭示了城市系统中城市人口和城市要素间普遍存在的非线性规模缩放关系,但目前大多数城市评价忽视了这种关系,常使用人均指标比较不同规模的城市,这会导致评价结果偏差。为此,考虑城市人口和城市要素间的非线性规模缩放关系构建了要素效能指数,用以修正城市规模的影响,度量城市要素实际发挥出预期能力的程度。以城市发展不同维度上的9个城市要素为例,分别测度了2017年中国292个地级以上城市各要素的效能,识别了各要素效能的空间差异和集聚特征,分析了要素效能指数的优势并讨论了结果的政策启示。结果表明：① 9个城市要素都符合“城市标度律”,其中8个要素与城市人口呈非线性规模缩放关系;从标度律的视角测度城市效能是必要而且可行的。② 城市综合经济、商业消费和公共财政效能普遍以东部沿海地区较高;东北地区的基础教育和中西部地区的公共交通效能较低;土地和水资源禀赋较高的地区对应的效能值并不高;大部分城市的生态绿地效能较低。600万人以上的城市中,杭州、深圳、天津的各维度效能表现较均衡。③ 与人均指标评价结果的对比证明要素效能指数能够修正人口规模对城市评价的影响,对常用的总量和人均指标是有益的补充。标度律视角下的城市效能测度能够给城市人口管理和城市要素发展的决策提供明确的指导方向,同时为不同规模大小的城市提供更客观的比较标准,对国家城镇体系规划和落实中国新型城市化战略具有积极意义。

Assessment of multidimensional performance for Chinese cities based on urban scaling law

Urban scaling laws reveal the universal non-linear scaling relationships between urban indicators and urban population size. However, most current urban assessments ignore this non-linear relationship and often use per capita indicators to compare cities of different sizes, which may bias the cognition of urban development. To address this problem, considering the non-linear scaling relationship between urban population size and urban indicators, an urban performance index (UPI) is constructed to correct the impact of the urban size and measure the degree to which the urban indicator actually exerted their expected abilities. Taking 9 urban indicators in multi-dimensions of urban development as examples, the performance of 9 dimensions in 2017 for 292 cities at prefecture level or above in China was measured, and the spatial differentiation and agglomeration characteristics were studied. The advantage of UPI and its policy implications are also discussed. The results show that: (1) All the nine urban indicators are in compliance with the urban scaling law, and eight of them have a non-linear scaling relationship with the urban population. It is feasible and necessary to measure urban performance from the perspective of scaling law. (2) The performance of urban comprehensive economy, commercial consumption and public finance is generally higher in the eastern region of China. The basic education in the northeast and the public transportation in the central and western regions perform relatively worse; the corresponding performance in areas with higher land and water endowments is not high; the ecological green space performance of most cities is low. Among major cities with a population of more than 6 million, Hangzhou, Shenzhen, and Tianjin have more balanced performance in all dimensions. (3) The comparison with the results of per capita indicators proves that the UPI can modify the impact of urban scale on urban assessment, which is a useful supplement to the total and per capita indicators. The assessment of urban performance based on the urban scaling law can provide clear guidance for the decision-making of urban population management and urban development, and at the same time provide more objective comparison lens for cities of different sizes. Our work is of significance to the implementation of China's new-type urbanization and national urban system planning.