Investigation into water resources sustainability (WRS) is vital for a regional sustainable development strategy. This paper aimed to quantitatively evaluate the WRS in mainland China using a three-layer indicator system. Three important factors significantly affecting WRS are: water resources quantity (WRQ), water intensity (WI) and water efficiency (WE). Assessment of the three indicators was carried out in 356 cities where each indicator was graded from "very low" to "very high" according to the value magnitude. China was then classified into four zones to differentiate regional variations of the impact of water intensity and efficiency on sustainability. Results showed that 34% of the areas had "medium" to "high" WI indicator values and 58% of the areas had "low" to "very low" WE indicator values. The indicator values of WI were ordered as Zone I > Zone II > Zone III > Zone IV; whereas the WRS were ordered as: Zone I < Zone II < Zone III < Zone IV. It is recommended that water resource policies be turned to a more sustainable management strategy in areas with high WI and low WE. Zone I regions should be focused on particularly with limited resources and extreme exploitation. The results provide a valuable basis for macro-level decision-making concerned with regional sustainable development strategy for the entire mainland China.
Keywords: Efficiency; Intensity; Sustainability; Water resources; Zonal classification.