长江经济带城市水资源利用效率的空间关联网络及形成机制

探讨城市水资源利用效率空间关联网络特征及其形成机制可为实现区域用水效率协同提升提供新的政策视角。本文以长江经济带107个地级及以上城市为研究样本,首先,利用随机前沿分析法（SFA）测算出其2009—2018年水资源利用效率,并基于此构建其空间关联矩阵,继而采用社会网络分析法考察城市水资源利用效率空间关联网络的整体结构、个体结构及其空间聚类方式,最后采用二次指派程序法探讨网络形成机制。结果表明：① 城市水资源利用效率整体仍处于较低水平,但研究期内提升显著,空间关联网络格局显现,且整体网络可达性较强,几乎不存在非对称性可达的联系对,仍存在关联不紧密、网络结构稳定性欠佳等问题;② 上中下游地区的中心城市发挥着中心行动者、中介沟通者的重要作用,呈现“中心城市—非中心城市”的“核心—边缘”空间分布特征;③ 城市水资源利用效率空间关联板块可划分为净溢出、主受益和双向溢出板块,各板块成员组成符合长三角城市群、长江中游城市群、成渝城市群的分布特征;④ 城市间地理邻近性差异、经济发展水平差异、对外开放程度差异等自然地理条件和社会经济因素对城市水资源利用效率关联网络的形成具有显著影响。

Spatial correlation network and its formation mechanism of urban water utilization efficiency in the Yangtze River Economic Belt

Analyzing the characteristics and formation mechanism of the spatial correlation network for urban water utilization efficiency has important policy implications for improving coordination and efficiency of regional urban water utilization. In this paper, we take 107 cities at prefecture level and above located in the Yangtze River Economic Belt as the research area. We calculate the water utilization efficiency from 2009 to 2018 by using the stochastic frontier analysis and construct the spatial correlation matrix. We also investigate the overall structure, individual structure, and spatial clustering mode of the spatial correlation network of urban water utilization efficiency based on the social network analysis, and explore the network formation mechanism based on the quadratic assignment procedure. The empirical results indicate that: First, the overall utilization efficiency of urban water is still at a low level, but has improved significantly with the appearance of the spatial correlation network pattern. The overall network has good accessibility and little asymmetry exists between connection pairs. However, there are still some problems such as loose correlation and poor stability of network structure. Second, the central cities in the upper, middle and lower reaches act as the main undertakers and intermediary communicators, showing the spatial distribution characteristics of "core-periphery" among the central and marginal cities. Third, the spatial correlation plates of urban water utilization efficiency can be divided into the net spillover, main benefit and two-way spillover plates, following the distribution characteristics of the urban agglomerations in the Yangtze River Delta, the middle reaches of the Yangtze River, and the Chengdu-Chongqing region. Last, geographical proximity, economic development, openness, and other natural geographical conditions and socio-economic factors have significant impacts on the formation of the urban water utilization network.