Sustainability assessment of critical natural capital: a case study of water resources in Qinghai Province, China

One of the major challenges in the 21st century is the promotion of the development of human society while simultaneously safeguarding the resilience of the natural capital. To achieve this, the key lies in quantifying the pressures human activities exert on the natural capital at different scales. Furthermore, the extent to which these pressures maintain or threaten the natural capital threshold also needs to be identified, as this is the prerequisite for sustainable actions. This is particularly important for critical natural capital that provides vital ecosystem services, e.g., water resources. This study investigates Qinghai Province and its cities (prefecture-level administrative divisions), known as “China’s Water Tower”. The blue water footprint was systematically integrated with the freshwater use indicator of planetary boundaries framework to characterize the sustainability of the freshwater use in the study area from 2005 to 2017. Moreover, the main driving factors were analyzed, and targeted policies are proposed. The findings showed that: (1) The consumption of water resources in Qinghai Province first peaked in 2011, and then followed an increasing trend over the following years. The water resources were mainly consumed by agricultural irrigation, and the internal water resources consumption among cities was mainly concentrated in Xining and Haidong. (2) The use of water resources in Qinghai Province and its cities was sustainable, with the exception of both Xining and Haidong, where the use of water resources was in a high-risk state. (3) The growth of the consumption of water resources in Qinghai Province was mainly driven by the per capita GDP (486.37%), followed by population size (40.13%), and water footprint structure (0.14%). Water use efficiency (−426.64%) was a decisive factor that slowed down the growth of the consumption of water resources. Similar to the overall situation in Qinghai Province, the positive and inhibitory factors for the growth of the consumption of water resources in Xining and Haidong were mainly per capita GDP and water use efficiency, respectively. Qinghai Province, and Xining and Haidong in particular, should focus on reducing the intensity and improving the efficiency of its water use in the future.