Channel Degradation Downstream from the Three Gorges Project and Its Impacts on Flood Level

Assessing the potential for change in the middle Yangtze River channel following impoundment of the Three Gorges Dam

“…The Three Gorges Dam does not greatly modify stream flow but the loss of sediment from the channel system has a substantial impact on bed mobility and the geomorphic and biotic complexity of the river, as has been shown elsewhere by, for example, Pohl (2004). Work on the downstream impacts on large river systems of multipurpose dams (Graf, 1980;Andrews, 1991;Kearsley et al, 1994;Topping et al, 2000;Li et al, 2009) indicate that downstream geomorphic responses of stream channels to dams are complex and variable and difficult to predict, mainly because the effects of local geological conditions and operational details confound and complicate efforts to apply models and generalisations to individual streams (Phillips, 2003). The channel immediately downstream from a dam will normally undergo bed degradation and bank erosion due to the clear water released from the dam.…”

Shrinking of Dongting Lake and its weakening connection with the Yangtze River: Analysis of the impact on flooding

“…Since the TGP was put into operation, the flood situation in the middle and lower reaches of the Yangtze River has evidently improved (Hayashi et al, 2008;Li et al, 2009;Zhou et al, 2009). It is important, however, to gain an understanding of the likely development regarding the future flood risk.…”

Seasonal variations in composite riverbank stability in the Lower Jingjiang Reach, China

“…1a. There are three diversion branches at Songzikou, Taipingkou and Ouchikou in this reach, linking the Middle Yangtze River with the Dongting Lake, which usually divert water from the main stream during flood seasons but are normally dry during non-flood seasons (Li et al, 2009). With the boundary at Ouchikou, the total Jingjiang Reach is usually divided into upper and lower reaches.…”

“…Before the completion of the Three Gorges Dam (TGD), the LJR channel was under slight aggradation from 1975 to 2002, with an accumulated deposition volume of about 0.5 Â 10 8 m 3 (CWRC, 2013). After the TGD completion in 2003, the majority of sediment is being deposited in the reservoir region, and the released clear water is causing downstream channel degradation, with the channel regime being kept stable in general (Li et al, 2009;Chen et al, 2010;Yuan et al, 2012). However, continuous channel degradation has led to significant bank erosion processes in local regions of the LJR, with a maximum bank retreat of more than 100 m at several sites.…”