Water Resources Security Status Alteration and Its Attribution Analysis in the Three Outlets of Southern Jingjiang River after the Operation of the Three Gorges Reservoir
Based on the concept of driving-force-pressure-state-impact-response (DPSIR) model, an evaluation index system for water resources safety in the three outlets of southern Jingjiang River was established, and a fuzzy comprehensive evaluation based on entropy weight is carried out on water security status in this region during 2000-2015. Based on the factor analysis method, the changes of water security status in the region was analyzed. The results showed that: during the period 2000-2015, the overall water resources security in the three outlets was dominated by the Grade Ⅲ, accounting for 45.83%, which was still in the middle level. Water resources security showed a significant spatial and temporal variations. 1) From the perspective of time, water security status in Huarong County increased from Grade Ⅱ in 2000 to Grade Ⅴ in 2015, and the degree of membership to high levels became higher and to low levels became lower in general; water security status in Anxiang were Grade Ⅳ-Ⅴ during 2000-2002 and dropped to Grade Ⅲ after the operation of the Three Gorges Reservoir, but the change of membership degree to each level was small, and the growth of membership degree to high levels was slow. During this period, water security status in Nanxian County fluctuated most intensely. It dropped from Grade Ⅲ to Grade Ⅱ during 2000-2002 and slowly rose to Grade Ⅲ again after 2003. However, after 2010, its state of water resources safety fell from Grade Ⅱ to Grade Ⅰ and remained at Grade Ⅰ for three consecutive years during 2011-2013. After the operation of the Three Gorges Reservoir, the water resources security degree in Nanxian County fluctuated greatly and mainly moved from high level to low level. 2) From the perspective of space, before the operation of the Three Gorges Reservoir, water security status in the three outlets ranked from high to low was Anxiang, Nanxian and Huarong. In the initial operation period, the order was Anxiang, Huarong and Nanxian. In the trial operation period, it was Huarong, Anxiang and Nanxian. 3) Human economic activity and water supply capacity were the main contributing factors that affected the water resources security in the three outlets, whose variance contribution rates were 26.758% and 25.587%, respectively. The climate and population factors were the secondary factors, whose variance contribution rates were 16.240% and 15.469%, respectively.