Local human activities overwhelm decreased sediment supply from the Changjiang River: Continued rapid accumulation in the Hangzhou Bay-Qiantang Estuary system

Xie, Dongfeng; Pan, Cunhong; Wu, Xi; Gao, Shu; Wang, Zheng Bing

doi:10.1016/j.margeo.2017.08.013

Cited by 66 publications

(48 citation statements)

References 46 publications

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“…The volume over the YG section has a decreasing trend which is related to the large-scale embankment in the Qiantang Estuary in the last decades (Xie et al, 2017b). Overall, the seasonal variation of the volume at YG section is opposite to that of ZY section, with the mean volumes 3304, 3173 and 3285×10 6 m 3 , in April, July and November respectively, indicating the active sediment exchange between the two sections.…”

Section: Resultsmentioning

confidence: 93%

“…The maximum volume change in the wet season of 1995 over ZY and YG sections can be 200 and 400×10 6 m 3 , respectively. It should be noted that the volume changes of the ZY and YG sections are not always comparable because there exists active sediment exchange between the YG section and the lower estuary, i.e., the Hangzhou Bay (Chen et al, 1990;Han et al, 2003;Xie et al, 2017b).…”

Section: Resultsmentioning

confidence: 99%

“…Recent modeling by Xie et al (2017a) found that the deposits would grow unlimitedly under normal discharge condition due to the continuous sediment import by flood dominance, and the growth can be constrained by high discharge. Xie et al (2017b) also analyzed the morphological response of the Qiantang Estuary-Hangzhou Bay system to the reduction of sediment load from the adjacent Changjiang Estuary and the large-scale embankment within the estuary. However, few field data have been reported on the morphological equilibrium, leaving a gap between the sediment transport and morphological evolution because of the lack of observed hydrological data.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Morphodynamics of the Qiantang Estuary, China: Controls of river flood events and tidal bores

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Morphodynamics of the Qiantang Estuary, China: Controls of river flood events and tidal bores

et al. 2018

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“…Longshore sediment transport is hardly affected by a declining fluvial sediment supply as long as sediments derived from delta erosion effectively compensate for the decrease in fluvial sediment supply. For example, rapid vertical accretion and lateral progradation are currently observed in the coastal wetlands of Hangzhou Bay, which is located immediately south of the Yangtze Delta (Xie et al ). This mechanism could also be responsible for the formation of large accreting flanking spits due to deposition of sediment eroded from the protruding fronts of several Mediterranean deltas as documented recently by Besset et al ().…”

Section: Discussionmentioning

confidence: 99%

Role of delta‐front erosion in sustaining salt marshes under sea‐level rise and fluvial sediment decline

Yang

Luo

Temmerman

et al. 2020

Limnology & Oceanography

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Accelerating sea-level rise and decreasing riverine sediment supply are widely considered to lead to global losses of deltaic marshes and their valuable ecosystem services. However, little is known about the degree to which the related erosion of the seaward delta front can provide sediments to sustain salt marshes. Here, we present data from the mesomacrotidal Yangtze Delta demonstrating that marshes have continued to accrete vertically and laterally, despite rapid relative sea-level rise ($10 mm yr −1) and a > 70% decrease in the Yangtze River sediment supply. Marsh progradation has decelerated at a lower rate than fluvial sediment reduction, suggesting an additional source of sediment. We find that under favorable conditions (e.g., a mesomacrotidal range, strong tidal flow, flood dominance, sedimentary settling lag/scour lag effects, and increasing high-tide level), delta-front erosion can actually supply sediment to marshes, thereby maintaining marsh accretion rates in balance with relative sea-level rise. Comparison of global deltas illustrates that the ability of sediment remobilization to sustain marshes depends on coastal processes and varies by more than an order of magnitude among the world's major deltas. Salt marshes are among the world's most valuable ecosystems (Costanza et al. 1997). They sequester carbon, protect shorelines from storm impacts, transform nutrients, contribute to fisheries production, and maintain biodiversity (Barbier et al. 2011; Kirwan and Megonigal 2013; Temmerman et al. 2013; Möller et al. 2014). Unfortunately, many salt marshes have disappeared due to reclamation and waste disposal during the past century (Gedan et al. 2009; Ma et al. 2014). Deltaic marshes are one of the most dynamic landscapes on Earth's surface (Wagner et al. 2017) and are threatened by accelerating sea-level rise and decreases in fluvial sediment supply. Decreasing fluvial sediment supply reduces the ability of salt marshes to accumulate sediments and to build up their soil elevation in balance with the rising sea level (Kirwan et al. 2010; Weston 2014). Although the morphology and evolution of deltas are influenced by various factors (Paola et al. 2011), such as riverine water and sediment discharges (Besset et al. 2019), sediment properties (Caldwell and Edmonds 2014), flow patterns (Shaw et al. 2016), vegetation height and density (Nardin et al. 2016), marine hydrodynamics (waves, tides, and longshore currents) (Caldwell and Edmonds 2014; Besset et al. 2017), land subsidence and sea-level changes (Jerolmack 2009; Syvitski et al. 2009), changes in the fluvial sediment supply and relative sea level are usually the most important for the long-term morphological evolution of deltaic marshes. The rate of global mean sea-level rise increased from 1.

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“…Additionally, sediment grains are the carriers of organic matters and nutrients, exerting a vital role in the migration and circulation of matter [11]. Therefore, studies related to suspended sediment transport and sediments migration have gained increasing attention [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Transport Mechanism of Suspended Sediments and Migration Trends of Sediments in the Central Hangzhou Bay

Song

Shi

Zhang

et al. 2020

Water

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Based on the 2013 field survey data of hydrology, suspended sediments and bottom sediments in the Central Hangzhou Bay, this paper explores the dynamic mechanism of suspended sediments in Hangzhou Bay by employing material flux decomposition. Meanwhile, the migration trends of bed sediments are also investigated by analyzing grain size trends. The results show that during an ebb or flood tide, the hydrograph of suspended sediment concentration of Hangzhou Bay is dominated by an M shape (bimodal), which is attributed primarily to the generation of a soft mud layer and a separate fluid mud layer. Laterally, the distribution of suspended sediment concentration is high in the south and low in the north. From a macroscopic perspective, the net sediment transport in the study area displays a “north-landward and south-seaward” trend, presenting a “C”-shaped transport mode. That is, the sediments are transported from the bay mouth to the bay head on the north side and from the bay head to the bay mouth on the south side. The sediment transports by advection and tidal pumping are predominant, while the sediment transport by vertical circulation makes little contribution to the total sediment transport. Moreover, the sediment transport in the center of the reach area is dominated by advection, whereas that near both sides of the banks is controlled by tidal pumping. The asymmetry of the tides, i.e., flood-dominance in the north and ebb-dominance in the south, is the primary cause of the dynamic mechanism for the overall “C”-shaped transport mode in Hangzhou Bay. Additionally, coupled with the narrow-head wide-mouth geomorphology, Hangzhou Bay remains evolving by south shore silting and north shore scouring.

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Local human activities overwhelm decreased sediment supply from the Changjiang River: Continued rapid accumulation in the Hangzhou Bay-Qiantang Estuary system

Cited by 66 publications

References 46 publications

Morphodynamics of the Qiantang Estuary, China: Controls of river flood events and tidal bores

Morphodynamics of the Qiantang Estuary, China: Controls of river flood events and tidal bores

Role of delta‐front erosion in sustaining salt marshes under sea‐level rise and fluvial sediment decline

Transport Mechanism of Suspended Sediments and Migration Trends of Sediments in the Central Hangzhou Bay

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