Operating Effects of the Three Gorges Reservoir on the Riverbed Stability in the Wuhan Reach of the Yangtze River

Abstract

Reservoir construction may modify the downstream flow and sediment transport, and correspondingly result in adjustments in morphodynamics of a river, especially riverbed instability. Based on hydrological datasets from 2003 to 2019 during the post-dam period using the topographic data of 57 fixed cross-sections in the Wuhan reach of the Yangtze River, we calculated the indexes representing the channel stability. Moreover, considering the effects of flow, sediment concentration, grain size of sediment, and water depth, we propose a method for calculating the equilibrium values of cumulative erosion and the lateral migrate intensity of thalweg in this paper, and the method combines with the delayed response model (DRM) to comprehensively analyze the variations in the longitudinal and lateral stabilities of the riverbed. The results revealed that the channel has been obviously eroded in the downstream reach, resulting in a 76% decrease in sediment discharge after the impoundment of the Three Gorges Reservoir (TGR). Specifically, in the past 17 years, the cumulative erosion in the Wuhan reach of the Yangtze River reached 1.72 m, while the bankfull depth increased by 1.87 m. The lateral migrate intensity of thalweg increased in response to Coriolis force, with an increase of 22.3%. Taken together, the results show that the proposed formula can effectively simulate the variation process of channel stability, and it also quantifies the extent of the influence weight of interannual flow and sediment regimes. The morphodynamics adjustments in the channel stability of our studied reach were closely related to the previous five-year flow and sediment regimes, implying that channel evolution may lag behind the changes in flow and sediment discharges.

Anti-seasonal flooding drive substantial alterations in riparian plant diversity and niche characteristics in a unique hydro-fluctuation zone

“…And we found some invasive plants such as E. annuus began to show dominance in the vegetation composition of the new riparian forest in the TGR. The TGR area is not only one of the most biodiverse areas in China, but also one of the most endemic species areas in the world (Jin et al, 1984). The dominance of invasive plants can cause great harm to the gene pool and genetic diversity in the TGR area Ge et al, 2020).…”

Removal of Residual Chlorine from Stormwater Using Low-Cost Adsorbents and Phytoremediation

“…The resulting disinfected surfaces were washed, and their chlorine-containing runoff and stormwater were stored in reservoirs. Increased amounts of residual chlorine and disinfection by-products have been found in rivers and lakes as well [17,18]; studies demonstrate that more than 0.4 mg/l of residual chlorine and about 8.8 µg/L of disinfection by-products have been obtained from these water bodies [19,20]. Other studies show that some countries use swimming pool water for the irrigation of green areas [21], which contributes to the release of residual chlorine into the environment.…”

A Method for Riverway Erosion and Deposition Calculation Using Measured Cross-Sections

“…The calculation of erosion and deposition in riverways plays a pivotal role in studying river morphology, performing comprehensive river management and ensuring flood safety [1,2]. The erosion and deposition conditions are critical indicators for assessing the stability and safety of rivers, serving as essential bases for formulating river management and planning strategies [3][4][5].…”

“…1 Absolute Error = Calculated Value − Measured Value 2. Relative Error = (Calculated Value − Measured Value)/Measured Value.…”