Delta response to decline in sediment supply from the Yangtze River: evidence of the recent four decades and expectations for the next half-century

Yang, S.L.; Belkin, Igor M.; Belkina, A.I.; Zhao, Qing-ying; Jian, Zhu; Ding, Pingxing

doi:10.1016/s0272-7714(02)00409-2

Cited by 216 publications

(110 citation statements)

References 16 publications

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“…Changes in channel dimensions, kinematics, alluvial cover, and incision rates have been linked to variations in sediment supply for modern rivers (Massong and Montgomery, 2000) as well as experimental fluvial channels (Finnegan et al, 2007). Shoreline and delta architecture and progradation rates are strongly influenced by temporal and spatial changes in sediment supply (Yang et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Jobe¹,

Sylvester²,

Parker³

et al. 2015

Journal of Sedimentary Research

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Changes in sediment supply and caliber during the last ~130 ka have resulted in a complex architectural evolution of the Y channel system on the western Niger Delta slope. This evolution consists of four phases, each with documented or inferred changes in sediment supply. Phase 1 flows created wide (1,000 m), low-sinuosity (1.1) channel forms with lateral migration and little to no aggradation. During Phase 2, the Y channel system began to aggrade, creating more narrow (300 m) and sinuous (1.4) channel forms with many meander cutoffs. This system was abandoned at ~ 130 ka, perhaps related to rapid relative sea-level rise during MIS (Marine Isotope Stage) 5. Phase 3 flows were mud-rich and deposited sediment on the outer bends of the channel form, resulting in the narrowing (to 250 m), straightening (to a sinuosity of 1.22), and aggradation of the Y channel system. Renewed influx of sand into the Y channel system occurred with Phase 4 at ~ 50 ka, during MIS 3 sea-level fall. The onset of Phase 4 is marked by the initiation of the Y′ tributary channel, which re-established sand deposition in the Y channel system. Flows entering the Y channel from the Y′ channel were underfit, resulting in inner levee deposition that is most prevalent on outer banks, acting to further straighten (1.21) and narrow (to 200 m wide) the Y channel. The inner levees accumulated quickly as the flows sought equilibrium, with deposition rates > 200 cm/ky. Marked by the presence of the last sand bed, abandonment occurred at ~19 ka in the Y channel and ~15 ka in the Y′ channel and is likely related to progressive abandonment due to shelf-edge delta avulsion and/or progressive sea level rise associated with Melt Water Pulse 1-A. The muddy, 5-meter-thick Holocene layer has thickness variations that mimic those seen in the sandy part of Phase 4, suggesting that dilute, muddy flows continue to affect the modern Y channel system. This unique dataset allows us to unequivocally link changes in submarine channel architecture to variations in sediment supply and caliber. Changes in the updip sediment routing system (i.e. the channel "plumbing") are shown to have profound implications for submarine channel architecture and reservoir connectivity.

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Section: Introductionmentioning

confidence: 99%

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Jobe¹,

Sylvester²,

Parker³

et al. 2015

Journal of Sedimentary Research

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“…1), one of the largest rivers in the world, third in length (6,300 km), fourth in sediment load (until recently >400 million tons per year-Mt/year), and fifth in water discharge (∼900 km 3 /year) (Zhao et al 2000;Milliman et al 2010). More than 98% of the sediment discharge from the Yangtze is suspended load (Yang et al 2003). The bulk of the Yangtze's fresh water, sediment, and nutrients is discharged to the East China Sea (Yang et al 2010), resulting in one of the world's largest coastal fisheries and one of the world's largest deltaic cities, Shanghai, current population exceeding 20 million people.…”

Section: Introductionmentioning

confidence: 99%

Spatial, Temporal, and Human-Induced Variations in Suspended Sediment Concentration in the Surface Waters of the Yangtze Estuary and Adjacent Coastal Areas

Yang

Milliman

et al. 2012

Estuaries and Coasts

110

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To delineate temporal and spatial variations in suspended sediment concentration (SSC) in the Yangtze (Changjiang) Estuary and adjacent coastal waters, surfacewater samples were taken twice daily from 10 stations over periods ranging from 2 to 12 years (total number of samples >28,000). Synoptic measurements in 2009 showed an increase in surface SSC from 0.058 g/l in the upper sections of the estuary to ∼0.6 g/l at the Yangtze River turbidity maximum at the river mouth, decreasing seaward to 0.057 g/l. Annual periodicities reflect variations in the Yangtze discharge, which affect the horizontal distribution and transport of SSC, and seasonal winds, which result in vertical resuspension and mixing. Over the past 10-20 years, annual surface SSC in the lower Yangtze River and the upper estuary has decreased by 55%, due mainly to dam construction in the upper and middle reaches of the river. The 20-30% decrease in mean surface SSC in the lower estuary and adjacent coastal waters over the same period presumably reflects sediment resuspension, in part due to erosion of the subaqueous Yangtze Delta. SSCs in the estuary and adjacent coastal waters are expected to continue to decline as new dams are constructed in the Yangtze basin and as erosion of the subaqueous delta slows in coming decades.

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“…The Changjiang (Yangtze River) Estuary, about 120 km long and over 90 km wide at its outer limit, is a mesotidal estuary and characterized by the complexity of morphology associated multi-order bifurcations (Li and Zhang, 1998;Yang et al, 2003). Hangzhou Bay, the estuary of the Qiantang River, is dominated by macrotides.…”

Section: Introductionmentioning

confidence: 99%

pCO2 and carbon fluxes across sea-air interface in the Changjiang Estuary and Hangzhou Bay

Gao

Song

et al. 2008

Chin. J. Ocean. Limnol.

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Partial pressure of CO 2 (pCO 2 ) was investigated in the Changjiang (Yangtze River) Estuary, Hangzhou Bay and their adjacent areas during a cruise in August 2004, China. The data show that pCO 2 in surface waters of the studied area was higher than that in the atmosphere with only exception of a patch east of Zhoushan Archipelago. The pCO 2 varied from 168 to 2 264 μatm, which fell in the low range compared with those of other estuaries in the world. The calculated sea-air CO 2 fluxes decreased offshore and varied from −10.0 to 88.1 mmol m -2 d -1 in average of 24.4 ± 16.5 mmol m -2 d -1 . Although the area studied was estimated only 2 × 10 4 km 2 , it emitted (5.9 ± 4.0) × 10 3 tons of carbon to the atmosphere every day. The estuaries and their plumes must be further studied for better understanding the role of coastal seas playing in the global oceanic carbon cycle.

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Delta response to decline in sediment supply from the Yangtze River: evidence of the recent four decades and expectations for the next half-century

Cited by 216 publications

References 16 publications

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Rapid Adjustment of Submarine Channel Architecture To Changes In Sediment Supply

Spatial, Temporal, and Human-Induced Variations in Suspended Sediment Concentration in the Surface Waters of the Yangtze Estuary and Adjacent Coastal Areas

pCO2 and carbon fluxes across sea-air interface in the Changjiang Estuary and Hangzhou Bay

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