Evolution characters of water exchange abilities between Dongting Lake and Yangtze River

Abstract

By using field-survey hydrological data of the related control stations in Dongting Lake and the Yangtze River mainstream in 1951-2010, the evolution characters of water exchange abilities between the two water bodies and their response to the operation of the Three Gorges Reservoir (TGR) from different time scales are analyzed based on their hydraulic relations. The results are shown as follows. Firstly, during July-September, the replenishment ability of Three Outlets to Dongting Lake is stronger, and in January-March, the replenishment ability of Dongting Lake to Yangtze River is stronger. Secondly, there has been an obvious inter-decadal wave on the water exchange coefficient between Dongting Lake and Yangtze River. In 1951-1958 and 1959-1968, the replenishment ability of Three Outlets to Dongting Lake was stronger, but in 2003-2010, the replenishment ability of Dongting Lake to Yangtze River has been strengthened. Thirdly, the spill-division ability of Three Outlets weakens, and the water of Dongting Lake coming from Three Outlets decreases either in typical years or under different dispatching modes of the TGR after the operation of the Three Gorges Reservoir. Furthermore, the water of Dongting Lake coming from Four Rivers takes the dominant position, which obviously enhances the replenishment ability of Dongting Lake to Yangtze River. Fourthly, if the effect of the runoff fluctuation in the basin is not considered, the evolution characters of the exchange capacities and the exchange process between Dongting Lake and Yangtze River in different time scales are generally changed with the variation of the water exchange amount between them, although the factors influencing the water exchange capacities between them is very complex. These show that there is an in-line growth or decline relation between the river-lake water exchange ability and the river-lake water exchange amount.

Evolution of Flood Regulation Capacity for a Large Shallow Retention Lake: Characterization, Mechanism, and Impacts

“…In view of its potential impacts on the flood regulation capacity, the lake-river relationship evolution caused by the operation of the Three Gorges Reservoir has attracted more attention. The long-term decrease of diversion ratio of water and sediment from the Yangtze River to the Dongting Lake is becoming the primary factor affecting the flood regulation capacity [15,21,44]. From Figure 5a, the sediment from the Dongting Lake catchment has start to decrease since 1983, and the sediment from the upper Yangtze has decreased since 2000.…”

“…The failure of management on wetlands often results in big impacts on storm water retention [13,14]. The volume, extent, and shape of a lake are the basic aspects that determine its regulation capacity [15]. The evolution of a lake-river relationship further complicates the regulation processes [13,16,17]; associated with other human and natural impacts, the regulation processes often exhibit different patterns and rhythmic [7,18].…”

“…The changes in the area of the lake and the effects of such changes on flood regulation capacity have been extensively discussed [15,22]. In particular, studies have disputed the understanding of the new phenomenon of "normal discharge, high water level and disaster" in Dongting Lake since the 1990s, in view of changes in the flood regulation capacity [27,28].…”

Quantitative assessment of hydrological alteration over multiple periods caused by human activities at the Jingjiang Three Outlets, China

“…The closure and water storage capability of dams obviously changed water and sediment regimes of the downstream reach and subsequently affected the geomorphology of the riverbed (Zhang et al 2013;Han et al 2017). The Jingjang Three Outlets (JTO), as the water and sediment connecting channels between the Yangtze River and the Dongting Lake (Zhang et al 2015), play a major role in flood control (Hu et al 2015;Sun et al 2018), Dongting Lake evolution (Chang et al 2010;Ou et al 2014;Wang et al 2017), and ecological environment (Wu et al 2017;Yu et al 2018;Wu et al 2019). However, hydrological regimes at the JTO (Songzi, Taiping, and Ouchi) had been changed obviously, which was comprehensively caused by the Jingjiang Cutoffs (JC), the Gezhou Dam (GD), and the Three Gorges Dam (TGD) over the past 60 years (Li et al 2016;Zhu et al 2016;Wang et al 2017).…”

Macroinvertebrate assemblages in relation to environments in the dongting lake, with implications for ecological management of river‐connected lakes affected by dam construction

“…The operation of hydropower stations has changed the original processes of taking in ‐ sending out water, as well as the original input and output mode of sediment and nutrient in the river‐connected lakes . After the operation of the Three Gorges Dam (TGD), replenishment ability of the Dongting Lake to the Yangtze River has been strengthened . In the Dongting Lake, sediment deposition becomes slower due to reservoir intercepting sediment , and annual distribution of the runoff becomes more uniform, especially, low water period occurs ahead of time and prolongs .…”