Research on water resources environmental carrying capacity (WRECC) based on support-pressure coupling theory: A case study of the Guangdong-Hong Kong-Macao Greater Bay Area.

Water scarcity and water pollution problems are becoming increasingly serious in many regions of the world due to rapid socioeconomic development. Water resources environmental carrying capacity (WRECC), which embodies the attributes of social, economic, resource and environmental aspects, is usually considered as a significant metric to guide regional sustainable development. Most existing studies on WRECC mainly focus on conceptual discussions and evaluation methods, lacking a systematic insight into the theoretical connotations of WRECC and neglecting the interaction mechanisms within the WRECC system. Therefore, this study aims to propose a new WRECC evaluation method based on support and pressure theory to deeply reveal the state change and driving mechanisms of WRECC. Firstly, a WRECC evaluation system incorporating support and pressure is constructed and the WRECC performance is determined by both the support index and pressure index. Subsequently, the catastrophe progression method and the obstacle degree model are introduced to quantify the WRECC and identify the primary influencing factors. Lastly, the feasibility and validity of this methodology are verified through an empirical application in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). The results indicate that the WRECC of the GBA presents an upward trend from 2010 to 2019, shifting from a low-value load state to a low-value surplus state. Moreover, the WRECC performance varies significantly among cities in the GBA, especially for edge cities that generally exhibit higher support, pressure and WRECC indices than central cities. In addition, common obstacles that affect WRECC are total water resources, water resources per capita, water consumption per hectare for agriculture and proportion of the tertiary industry. Furthermore, this study reveals that the coupling relationship between support and pressure develops towards a positive direction, and water environment protection and economic development are the main drivers of WRECC development. This new proposed methodology can provide a theoretical reference for investigating regional WRECC and formulating appropriate sustainable development strategies.