Integrating water-related disaster and environment risks for evaluating spatial–temporal dynamics of water security in urban agglomeration

Water security is a compound concept coupling multi-dimensional perspectives, such as resource utilization, environmental protection, and disaster prevention. With this concern, this study focuses on the spatial–temporal dynamics of water security with considering water disaster risk index (WDRI), water environment risk index (WERI), and water supply–demand. WERI centers on risk source’s hazard, control effectiveness, and risk receptor’s vulnerability. Indices related to hazard, exposure, and vulnerability are used for evaluating WDRI. A multi-objective fuzzy membership function is presented for determining the indices’ weight, and the distribution pattern of water security is illustrated based on cluster analysis. A real-world case study of Beijing-Tianjin-Hebei urban agglomeration (BTHUA) is given for verifying availability of the evaluation framework. Results indicate the general water security in BTHUA with a critical safe state yet a downward trend. Opposite change characteristics of water security exist between its southern and northern cities. WDRI and WERI show the trends of increasing (with a growth rate of 0.48%) and decline (with an average decrement rate of 0.56%), respectively. Beijing has high-value WDRI and WERI, and the order of WDRI and WERI is presented as follows: Beijing (0.67) > Tianjin (0.54) > Hebei (0.33) and Beijing (0.69) > Tianjin (0.58) > Hebei (0.16), respectively. Cluster analysis reveals a poor match relation between water security and regional socio-economic development. Areas with high-level economic development (e.g., Beijing and Tianjin) have poor environmental performances, with WDRI and WERI of 0.54 ~ 0.68 and 0.57 ~ 0.70, respectively. Additionally, water resources overload index of BTHUA is 8.513, which is higher than Chengdu-Chongqing urban agglomeration (1.431), Triangle of Central China (0.228), and Yangtze River Delta urban agglomeration (0.742). Findings can provide a theoretical reference for promoting sustainable utilization of water resources in BTHUA and the other areas with prominent water problems.