Coordination degree of the exploitation of water resources and its spatial differences in China.

Coordinated relationships between socioeconomic development and water utilization, as well as environmental protection measures, are crucial for achieving sustainable water resource exploitation (WRE) under changing environmental conditions. Moreover, a balanced condition of regional WRE is essential to guaranteeing the water security of the entire nation. In this study, an evaluation model of the coordination degree (CD) of WRE is built based on 10 selected indicators and is then applied to 31 provincial zones in China during the period 2004-2014. The cluster analysis method is introduced to classify the relative rank (RK) of the CD at the provincial scale in the pre- (2004-2010) and post- (2011-2014) phases; these phases are divided by the first year of the implementation of the "Three Red Lines Policy" in China (2011), and the spatial differences of the CD of the entire nation were decomposed. The results showed the following. 1) The CD of WRE increases significantly in 26 provincial zones after the implementation of the "Three Red Lines Policy", and the average CD of WRE for 28 provincial zones during the post-phase was greater than that during the pre-phase. 2) Provincial zones with the RK of coordinated development model (CDM) are mainly located in southern and southwestern China. Provincial zones with the RK of the uncoordinated development model (UDM) were mainly found in northern inland China. Eight provincial zones with dense populations and intensive water use, but with only scarce per capita water resources, have the RK of the severely uncoordinated development model (SUDM). 3) The spatial differences in CD diminished in the post-phase, and the differences in CD at the inter-regional scale accounted for a predominant proportion of the difference in CD at the national scale. In addition to improving the coordination status of WRE, the implementation of the "Three Red Lines Policy" also decreased the disparity among the CD of WRE, and this policy continued to be effectively implemented and followed to make a lasting difference. Cross-regional cooperation and coordinated relationships between socioeconomic development and water resource protection are needed to achieve a more coordinated and balanced WRE for long-term development. The results of this study have scientific and practical implications for sustainable WRE and water security in rapidly developing countries such as China.