Evaluation of hydrological regime alteration and ecological effects in the middle and lower of the Yangtze River, China

Abstract

Abstract The flow regime is regarded as the key driver of the structure and function of riverine ecosystems. This study uses an ecologically meaningful indicator (range of variability approach method) to assess the dynamic runoff process in the middle and lower reaches of the Yangtze River, whose changes negatively affect the ecosystems in the study area. In addition, the study quantitatively analyzed the contribution rate of human activities and climate change to flow change. The effects of ecological index changes on four famous major carp species (FFMC) resources in the middle and lower reaches of the Yangtze River were studied. The results show that after the Three Gorges Dam (TGD) operation, the hydrological changes of Yichang Station, Hankou Station, and Datong Station were 65, 58, and 46%, respectively. The weight of the impact of human activities on runoff is smaller the farther away from the TGD. The impact weights of human activities at the three hydrological stations in the middle and lower reaches of the Yangtze River are 73.69, 67.98, and 56.84%, respectively. The operation of the Three Gorges Project caused changes in the hydrological regime of the Yangtze River, which adversely affected the structure and quantity of FFMC populations.