Risk assessment of water resources and environmental carrying capacity in Yinchuan city

Regional sustainable development is a critical requirement for natural resources management and socio-economic sustainability, in which water resource is one of the most important supports. The present study proposed a method to calculate water resources carrying capacity (WRCC) and water environmental carrying capacity (WECC) to assess the scale of economy and population that the local water resources can support in Yinchuan City, a semi-arid area in Northwest China. Carrying population and gross domestic product (GDP) were selected as the characteristic indices of carrying capacity. The urban water demand and supply data were used to calculate the WRCC, NH3-N and chemical oxygen demand with K2Cr2O7 as the oxidizing agent (CODCr) were used to calculate the WECC. Carrying index was employed to assess the carrying status and risk of water resources and environment in 2010, 2015 and 2020, respectively. The results show that the environmental capacity of Yinchuan in terms of NH3-N in different years can carry higher GDP than the CODCr water environment, and the CODCr WECC in terms of GDP is always the lowest among the three years. It can be seen that the WECC of CODCr imposes the strictest restrictions on water utilization in Yinchuan city. The risk assessment of the carrying capacity indicates that CODCr pollution in 2015 is at unacceptable risk level. The CODCr pollution is a key factor affecting the economic and social development of Yinchuan city. The assessment results are beneficial to the assessment of WRCC and WECC in other similar areas.