Riverbed erosion of the final 565 kilometers of the Yangtze River (Changjiang) following construction of the Three Gorges Dam

The world’s largest hydropower dam, the Three Gorges Dam (TGD), spans the upper Yangtze River in China, creating a 660-km long and 1.1-km wide reservoir upstream. Several recent studies reported a considerable decline in sediment load of the Lowermost Yangtze River (LmYR) and a rapid erosion in the subaqueous delta of the river mouth after the closure of the TGD in 2003. However, it is unknown if the TGD construction has also affected river channel and bed formation of the LmYR. In this study, we compared bathymetric data of the last 565 kilometers of the Yangtze River’s channel between 1998 and 2013. We found severe channel erosion following the TGD closure, with local riverbed erosion up to 10 m deep. The total volume of net erosion from the 565-km channel amounted to 1.85 billion m3, an equivalent of 2.59 billion metric tons of sediment, assuming a bulk density of 1.4 t/m3 for the riverbed material. The largest erosion occurred in a 100-km reach close to the Yangtze River mouth, contributing up to 73% of the total net eroded channel volume.

[1]  F. Engelund,et al.  A monograph on sediment transport in alluvial streams , 1967 .

[2]  M. Wolman,et al.  Downstream effects of dams on alluvial rivers. , 1984 .

[3]  E. D. Andrews,et al.  Downstream effects of Flaming Gorge Reservoir on the Green River, Colorado and Utah , 1986 .

[4]  D. Stanley,et al.  Nile delta: extreme case of sediment entrapment on a delta plain and consequent coastal land loss , 1996 .

[5]  Nicola Surian,et al.  Channel changes due to river regulation: the case of the Piave River, Italy , 1999 .

[6]  S. Anders Brandt,et al.  Classification of geomorphological effects downstream of dams , 2000 .

[7]  Zhongyuan Chen,et al.  Yangtze River of China: historical analysis of discharge variability and sediment flux , 2001 .

[8]  Zhongyuan Chen,et al.  Impact on the Yangtze (Changjiang) Estuary from its drainage basin: Sediment load and discharge , 2001 .

[9]  M. Rinaldi.  Recent channel adjustments in alluvial rivers of Tuscany, central Italy , 2003 .

[10]  Shi-lun Yang,et al.  Delta response to decline in sediment supply from the Yangtze River: evidence of the recent four decades and expectations for the next half-century , 2003 .

[11]  C. Vörösmarty,et al.  Anthropogenic sediment retention: major global impact from registered river impoundments , 2003 .

[12]  N. Surian,et al.  Morphological response to river engineering and management in alluvial channels in Italy , 2003 .

[13]  Colin R. Thorne,et al.  Morphological changes of the Lower Mississippi River: geomorphological response to engineering intervention , 2005 .

[14]  D. Walling.  Human impact on land : ocean sediment transfer by the world's rivers , 2006 .

[15]  D. Wal,et al.  Long-term morphological change and its causes in the Mersey Estuary, NW England , 2006 .

[16]  Shi-lun Yang,et al.  Effect of deposition and erosion within the main river channel and large lakes on sediment delivery to the estuary of the Yangtze River , 2007 .

[17]  Jing Chen,et al.  Acoustic Doppler current profiler surveys along the Yangtze River , 2007 .

[18]  Laurence C. Smith,et al.  Climatic and anthropogenic factors affecting river discharge to the global ocean, 1951–2000 , 2008 .

[19]  M. Allison,et al.  Bedform transport rates for the lowermost Mississippi River , 2008 .

[20]  Li Yanyan,et al.  Channel sedimentation and erosion of the Jiangsu reach of the Yangtze River during the last 44 years , 2009 .

[21]  R. H. Meade,et al.  Causes for the decline of suspended‐sediment discharge in the Mississippi River system, 1940–2007 , 2009 .

[22]  X. Lu,et al.  A quantitative assessment of human impacts on decrease in sediment flux from major Chinese rivers entering the western Pacific Ocean , 2009 .

[23]  Jing Chen,et al.  Implications of flow control by the Three Gorges Dam on sediment and channel dynamics of the middle Yangtze (Changjiang) River, China , 2010 .

[24]  M. Church,et al.  Spatial and temporal variation of in‐reach suspended sediment dynamics along the mainstem of Changjiang (Yangtze River), China , 2010 .

[25]  Yan Wang,et al.  Recent changes in sediment delivery by the Huanghe (Yellow River) to the sea: Causes and environmental implications in its estuary , 2010 .

[26]  J. Milliman,et al.  50,000 dams later: Erosion of the Yangtze River and its delta , 2011 .

[27]  J. Gao,et al.  Sediment retention at the Changjiang sub-aqueous delta over a 57 year period, in response to catchment changes , 2011 .

[28]  P. Ashworth,et al.  How do big rivers come to be different , 2012 .

[29]  Jeffrey A. Nittrouer,et al.  Spatial and temporal trends for water-flow velocity and bed-material sediment transport in the lower Mississippi River , 2012 .

[30]  B. Finlayson,et al.  Assessing the potential for change in the middle Yangtze River channel following impoundment of the Three Gorges Dam , 2012 .

[31]  M. Lamb,et al.  Backwater and river plume controls on scour upstream of river mouths: Implications for fluvio‐deltaic morphodynamics , 2012 .

[32]  H. Swart,et al.  Effects of navigational works on morphological changes in the bar area of the Yangtze Estuary , 2012 .

[33]  M. Kirwan,et al.  Tidal wetland stability in the face of human impacts and sea-level rise , 2013, Nature.

[34]  E. Viparelli,et al.  Sand as a stable and sustainable resource for nourishing the Mississippi River delta , 2014 .

[35]  Z. Dai,et al.  Detection of the Three Gorges Dam influence on the Changjiang (Yangtze River) submerged delta , 2014, Scientific Reports.

[36]  R. Ferguson,et al.  Morphodynamics: Rivers beyond steady state , 2015 .

[37]  Edward J. Anthony,et al.  Linking rapid erosion of the Mekong River delta to human activities , 2015, Scientific Reports.

[38]  J. Syvitski,et al.  Profiling risk and sustainability in coastal deltas of the world , 2015, Science.

[39]  S. L. Yang,et al.  Decline of Yangtze River water and sediment discharge: Impact from natural and anthropogenic changes , 2015, Scientific Reports.

[40]  Shi-lun Yang,et al.  Decadal morphological evolution of the Yangtze Estuary in response to river input changes and estuarine engineering projects , 2016 .

[41]  E. Jeppesen,et al.  Impacts of Three Gorges Reservoir on the sedimentation regimes in the downstream-linked two largest Chinese freshwater lakes , 2016, Scientific Reports.

[42]  Min Zhang,et al.  Fluvial processes of the downstream reaches of the reservoirs in the Lower Yellow River , 2016, Journal of Geographical Sciences.

[43]  Heqin Cheng,et al.  Decadal changes in bathymetry of the Yangtze River Estuary: Human impacts and potential saltwater intrusion , 2016 .

[44]  Junqiang Xia,et al.  Dynamic channel adjustments in the Jingjiang Reach of the Middle Yangtze River , 2016, Scientific Reports.

[45]  Wei Zhang,et al.  Interacting effects of multiple factors on the morphological evolution of the meandering reaches downstream the Three Gorges Dam , 2017, Journal of Geographical Sciences.

[46]  S. L. Yang,et al.  Will river erosion below the Three Gorges Dam stop in the middle Yangtze , 2017 .

[47]  S. L. Yang,et al.  New evidence of Yangtze delta recession after closing of the Three Gorges Dam , 2017, Scientific Reports.

[48]  Jiang Yuehua,et al.  Morphology and mechanism of the very large dunes in the tidal reach of the Yangtze River, China , 2017 .

[49]  Shi-lun Yang,et al.  River-sea transitions of sediment dynamics: A case study of the tide-impacted Yangtze River estuary , 2017 .

[50]  Bo Wang,et al.  Decadal‐Scale Riverbed Deformation and Sand Budget of the Last 500 km of the Mississippi River: Insights Into Natural and River Engineering Effects on a Large Alluvial River , 2018 .