منطقه بندی ظرفیت حمل محیطی آب برای حمایت از مدیریت و توسعه منابع آب پایدار در چین Regionalization of water environmental carrying capacity for supporting the sustainable water resources management and development in China

1. Introduction Water environmental carrying capacity (WECC) refers to the primary ability of water bodies to supply resources to the socio-economic development and to remove the pollutants discharged by rural and urban areas and factories. It is an important indicator that reflects the regional sustainability and is closely related to the economy, population, technology and natural environment (Graymore et al., 2010; Liu and Borthwick, 2011). With a rapid economic growth and social development in China, the associated problems of water contamination and shortage of water resources have become serious bottlenecks which challenge and limit the sustainable development at the regional as well as at national levels (Chen et al., 2016a; Liu et al., 2017). The disordered spatial development and irrational processes in the urbanization and industrialization destroy the essential water environment thereby affecting the local people at this stage and potentially might affect their next generation, which further brings a huge threat to the sustainable development of these regions (Fan and Li, 2009). At present, an increasing number of researchers have realized that the scale and intensity of economic and social development cannot exceed certain carrying capacities of the water system in a specific region. At the same time, the potential damages to water system cannot threaten the survival and development of future generations (Gunderson, 2014; Hák et al., 2016; Tran, 2016). Thus, it is of great significance for local decision makers to be well aware of information related to carrying capacity of water environment within a specific region. China’s climate is mainly dominated by dry seasons and wet monsoons, which leads to prominent precipitation differences between the south and north provinces. Also, the eastern and coastal provinces are much more densely populated than the western and interior regions. The vast majority of population lives in major cities that are mainly located in the Yangtze River Delta, Pearl River Delta and North China Plain. The gap in GDP per capita between coastal and inland areas had increased from 200 Yuan in 1978 to 19,630 Yuan in 2008 (Fan et al., 2010). In addition, the eastern developed regions are affected with severe environmental problems of water due to overexploitation, for instance, the degradation of water quality in the regional environment. The western underdeveloped regions usually have vulnerable environment for water. Especially, the upstream areas of western rivers are the key conservation areas of water source and are the ecologically fragile districts in China (Fan and Li, 2009). Since the functions in regional economy and society and basic conditions for water environment are varied, and thus the corresponding strategies and development policies should be approached in a different way. The reasonable spatial arrangement targeting the development and conservation requires an urgent attention for the rapidly changing society in China (Liu et al., 2015). Zoning is an effective measure to divide an area into sub-areas based on similar characteristics in order to identify the differences between sub-areas and to implement the appropriate environmental management policies (Fadlelmawla et al., 2011; Oliveira et al., 2011; Shi and Zeng, 2014).