DPSRE model framework for dynamic evaluation of the water environment carrying capacity in a river network area of Taihu Lake, East China

A reasonable evaluation index system is very important for the scientific assessment of the water environment carrying capacity (WECC). The framework system of driving force-pressure-state -response-economic benefit (DPSRE) and one-vote veto mechanism were proposed, which was used to construct an evaluation index system for WECC. The analytic hierarchy process (AHP) was employed to analyze the WECC of Changxing County in Taihu Lake Basin, China, during the years from 2010 to 2018 and different water periods (wet, flat, and dry) in 2018. The results showed that the WECC of Changxing County fluctuatingly increased from 2010 to 2018 and the evaluation grade varied from critical overload to loadable, with the maximum value of 0.71 (load -able) in 2016 and the minimum value of 0.50 (overload) in 2015 and 2018. In addition, the WECC was loadable during the wet (0.75) and flat (0.74) water period, while overload in the dry water period (0.50) in 2018. Through analysis the influence weights of indicators, development and utili-zation ratio of water resources, domestic sewage treatment compliance rate, output tax of per unit emission right, vegetation coverage rate of riverbank, aquatic plants coverage rate of river were the major indicators affecting the WECC. By analysis the evaluation results, the improvement of WECC was attributed to the increase of economic benefit subsystem. The water quality compliance rate of regional exit section (S0) did not reach 100% was the real reason for the overload status of WECC in 2015, 2018 and the dry water period (2018). Ecological degradation of river and point and non-point source pollution were the most constraints to the WECC in Changxing County.