A new method to evaluate urban resources environment carrying capacity from the load-and-carrier perspective

Urban resources environment carrying capacity (URECC) is considered as a significant yardstick for guiding the practice towards sustainable urban development. It helps measure the interaction between human activities and urban resources environment system. Although existing studies on URECC have made great progress, there is still no consensus on the definition and evaluation method for URECC. In line with this background, this study proposes a theoretical method named URECC-LC from the load-and-carrier innovative perspective. In developing this method, urban resources environment is considered as a system, and the novel concepts of urban loads (UL) and urban carriers (UC) are introduced. Subsequently, the measurement of URECC is built up by incorporating both urban loads and carriers. This new method can be applied to evaluate effectively and properly the state of URECC. Several novel insights for this innovative method are highlighted as: (a) sustainable development based URECC assessment; (b) extension of URECC implication to urban resilience; (c) virtual threshold for measuring the limitation of URECC. Taking urban water resources environment as an example, a case demonstration with reference to cities Beijing, Tianjin, Shanghai and Chongqing in China is conducted, and the case results shows: (1) Beijing, Shanghai and Tianjin represents a URECC deficit state for water resources environment almost every year (2004-2017) and Chongqing shows a URECC surplus state during the whole surveyed period; (2) the resilience of urban water resources environment is differing between the four case cities; (3) Shanghai has the highest possibility (risk) for water resources environment carrying capacity to be overloaded, and the water resources environment carrying capacity in Chongqing has been less utilized. The demonstration conducted proves that the introduced URECC-LC method is applicable and effective in evaluating URECC. And this new method provides significant theoretical basis for studying urban resources environments.