Will river erosion below the Three Gorges Dam stop in the middle Yangtze?

Lai, Xin; Yin, Dong Min; Finlayson, Brian; Wei, Taoyuan; Li, M.; Yuan, Weili; Yang, S.L.; Dai, Zhijun; Gao, Shu; Chen, Zuoqi

doi:10.1016/j.jhydrol.2017.08.057

Cited by 87 publications

(71 citation statements)

References 11 publications

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“…For the purpose of water resources development and/or flood control, countless dams have been constructed on rivers around the world (Grill et al, 2015;World Commission on Dams, 2000). Although dams provide numerous socio-economic benefits, they also significantly perturb the natural flow regimes of rivers, thereby raising wide concerns over the potential environmental and ecological impacts (Graf, 2006;Jiang, Xiong, Xu, & Guo, 2015;Lai et al, 2017;Latrubesse et al, 2017;Magilligana & Nislow, 2005;Milliman, 1997;Schmidt & Wilcock, 2008;Vogel et al, 2007;Yang, Zhang, & Xu, 2007). The development of a rational strategy for operating dams therefore requires understanding of their effects on the downstream flow regime (Grill et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…The changes of the downstream flow process appear to be the most direct and apparent results of the regulation of the TGD and have been widely studied. It has been revealed that the TGD displayed multiple behaviours altering downstream flow characteristics, such as decreasing and increasing discharge during the impoundment and release periods, respectively, and attenuating extreme flood peaks (Dai, Du, Li, Li, & Chen, 2008;Gao et al, 2012;Lai et al, 2014Lai et al, , 2017Mei et al, 2018;Wang, Wang, Lewis, Wu, & Huang, 2017). These variations in flow process due to the TGD were found to induce further hydrological alterations in water levels, droughts, interrelationships between the river and lakes, and even ecosystems of the downstream region (Guo et al, 2012;Li, Xiong, Dong, & Zhang, 2013;Mei, Dai, van Gelder, & Gao, 2015;Wang et al, 2013;Wang, Rhoads, & Wang, 2016;Wang, Sheng, & Wada, 2017;Zhang et al, 2012;Zhang, Ye, et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Assessing the effects of the Three Gorges Dam and upstream inflow change on the downstream flow regime during different operation periods of the dam

Jiang

Zhang

Luo

2019

Hydrological Processes

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As the largest hydroelectric dam in the world, the Three Gorges Dam (TGD) has raised wide concerns over the environmental and ecological impacts since its dramatic effect on the downstream flow regime of the Yangtze River. Since 2003, the TGD has progressed from the initial operation period to the full operation period, with different effects on the downstream flow regime over each period. Although the upstream inflow change (USIC) of the TGD is a possibly additional factor affecting the downstream flow regime, this has drawn little attention. This study aims to quantify the individual contributions of the TGD and the USIC to the changes of the downstream flow regime over different operation periods of the dam. Using the Muskingum routing model and the Xin'anjiang rainfall–run‐off model, we reconstruct the discharge unregulated by the TGD for the post‐TGD period from 2003 to 2015. On this basis, the effects of the TGD and the USIC on the downstream flow regime are quantitatively assessed. Benchmarked against the flow regime during the pre‐TGD period from 1955 to 2002, it is found that the TGD and the USIC play considerable and comparable roles in affecting the downstream flow regime during the whole post‐TGD period from 2003 to 2015. Furthermore, the TGD appears to have a limited effect on the downstream flow regime during the initial operation period from 2003 to 2008 relative to the USIC. In contrast, during the full operation period from 2009 to 2015, the TGD plays a dominant role in changing the downstream flow regime, although the effect of the USIC cannot be neglected. The findings of this study are helpful to understand the exact impacts of the TGD on the downstream flow regime, thereby facilitating the development of a rational strategy for operating the dam.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Assessing the effects of the Three Gorges Dam and upstream inflow change on the downstream flow regime during different operation periods of the dam

Jiang

Zhang

Luo

2019

Hydrological Processes

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“…We estimated the suspended sediment‐carrying capacity using the equation based on gravitational theory by Zhang (Qian & Wan, ), which has been used to calculate the suspended sediment‐carrying capacity ( S w ) of the Middle‐Lower Yangtze River (Lai et al, ; Yuan, Yin, Finlayson, & Chen, ). The equation is as follows:

S_{w} = k {(\frac{U^{3}}{ghω})}^{m},

ω = 1.72 \sqrt{\frac{ρ_{s} - ρ_{w}}{ρ_{w}} italicgD},

where S w is sediment‐carrying capacity (kg/m 3 ); U is velocity (m/s); g is acceleration of gravity (m/s 2 ); h is the depth of water (m); ω is sediment‐settling velocity (m/s); ρ s and ρ w are the density of suspended sediment and water, respectively (kg/m 3 ); D is suspended sediment median grain size (mm); and k and m are coefficients and are calibrated by the measured data.…”

Section: Effects Of Water‐sediment Conditions and Human Activities Onmentioning

confidence: 99%

“…We estimated the suspended sediment-carrying capacity using the equation based on gravitational theory by Zhang (Qian & Wan, 2003), which has been used to calculate the suspended sediment- carrying capacity (S w ) of the Middle-Lower Yangtze River (Lai et al, 2017;Yuan, Yin, Finlayson, & Chen, 2012). The equation is as follows:…”

Section: Calculation Of Suspended Sediment-carrying Capacitymentioning

confidence: 99%

“…The effects of reservoir operation on water and load fluxes, riverbed deformation, and the environment are of public concern. The TGR has adopted a "peak clipping and low flow supplement" strategy (Hu & Fang, 2017;Mei, Dai, Gelder, & Gao, 2015;Zheng, 2016) to decrease discharges during storm seasons and increase discharges during drought seasons (Lai et al, 2017;Wang, Sheng, Gleason, & Wada, 2013). This strategy aims to minimize impacts on the total run-off (Chen et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Impact of the operation of a large‐scale reservoir on downstream river channel geomorphic adjustments: A case study of the Three Gorges

Yang

Zhang

Zhu

et al. 2018

River Research & Apps

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To evaluate the effects of reservoir construction on the geomorphology of downstream reaches, a case study is performed on the Three Gorges Reservoir (TGR) by comparing data collected before and after impoundment of the reservoir. This study focuses on a 1,183‐km‐long reach downstream from the TGR and investigates the temporal and spatial characteristics and patterns of geomorphic adjustment in the downstream reaches. The amount of erosion in flood plain channels and the annual average intensity of erosion in downstream reaches after 12 years of impoundment are larger than the predicted values before the impoundment of the TGR. The maximum intensity of erosion was found at 410 km from the dam, with an average thalweg incision of 1.5 m, and the main zone of erosion migrated approximately 80 km downstream. At both preimpoundment and postimpoundment, erosion occurred the along beaches and channels in the Yichang–Chenglingji reach. The pattern of erosional channels and depositional river floodplain changed to erosional channels and erosional river floodplain in the Chenglingji–Hankou reach after the trial impoundment stage. In the Hankou–Hukou reach, the erosional channels and depositional river floodplain pattern changed to erosional deep channels, erosional low beaches, and depositional high‐river floodplain during the early impoundment stage. After the trial impoundment stage, erosion continued in the deep channels, but minor deposition occurred on the river floodplain. Moreover, the discharge of clear water increased, and the duration from middle to low‐water levels increased, leading to more concentrated erosion in low‐water channels. The intensity of the erosion along the river floodplain decreased due to the shortened duration of high‐water levels and reduced human activity.

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Modulation of Extreme Flood Levels by Impoundment Significantly Offset by Floodplain Loss Downstream of the Three Gorges Dam

Mei

Dai

Darby

et al. 2018

Geophysical Research Letters

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River flooding—the world's most significant natural hazard—is likely to increase under anthropogenic climate change. Most large rivers have been regulated by damming, but the extent to which these impoundments can mitigate extreme flooding remains uncertain. Here the catastrophic 2016 flood on the Changjiang River is first analyzed to assess the effects of both the Changjiang's reservoir cascade and the Three Gorges Dam (TGD), the world's largest hydraulic engineering project on downstream flood discharge and water levels. We show that the Changjiang's reservoir cascade impounded over 30.0 × 103 m3/s of flow at the peak of the flood on 25 July 2016, preventing the occurrence of what would otherwise have been the second largest flood ever recorded in the reach downstream of the TGD. Half of this flood water storage was retained by the TGD alone, meaning that impoundment by the TGD reduced peak water levels at the Datong hydrometric station (on 25 July) by 1.47 m, compared to pre‐TGD conditions. However, downstream morphological changes, in particular, extensive erosion of the natural floodplain, offset this reduction in water level by 0.22 m, so that the full beneficial impact of floodwater retention by the TGD was not fully realized. Our results highlight how morphological adjustments downstream of large dams may inhibit their full potential to mitigate extreme flood risk.

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Will river erosion below the Three Gorges Dam stop in the middle Yangtze?

Cited by 87 publications

References 11 publications

Assessing the effects of the Three Gorges Dam and upstream inflow change on the downstream flow regime during different operation periods of the dam

Assessing the effects of the Three Gorges Dam and upstream inflow change on the downstream flow regime during different operation periods of the dam

Impact of the operation of a large‐scale reservoir on downstream river channel geomorphic adjustments: A case study of the Three Gorges

Modulation of Extreme Flood Levels by Impoundment Significantly Offset by Floodplain Loss Downstream of the Three Gorges Dam

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