UK - Department for Business, Energy and Industrial Strategy
Newton Fund - Natural versus anthropogenically driven behaviour of hydrodynamics and sediment dynamics in Yangtze Estuarian Delta
Project Data Last Updated: 27/08/2020
IATI Identifier: GB-GOV-13-FUND--Newton-EP_R02491X_1
Estuarine deltas are areas where the water and suspended sediment motion are primarily driven by the joint action of input of fresh water by rivers and tide from the sea. Besides being driven by these natural forcing agents, the hydrodynamics and sediment dynamics are frequently affected by a variety of different anthropogenic measures, such as channel dredging, land reclamation, engineering works for flow and sediment controls regulations in the estuaries, and dams in the upstream parts of watersheds. These human activities may lead to strong changes of flow and suspended sediment behaviour in the estuaries. During the last decades many estuarine systems in Europe (e.g. the Elbe, Ems, Loire) have shown increases in tidal range and in turbidity, which seem to be linked to deepening An estuarine delta system that faces similar problems as European estuaries is the Yangtze Estuary Delta(YED). Analysis of field data collected since the middle of the last century show that there are significant variations in morphological patterns of estuarine channels as well as of subaqueous deltas of the YED that are naturally generated over a thousand-year period. Compared to the European estuaries mentioned above, the YED is much larger in scales, experiences much stronger river discharge, and it is subject to a strong seasonal variation in fresh water. Moreover, it is a complex estuarine network with several branches, connecting channels and a complex delta. The changes of the flow and sediment dynamics in the estuary may result from both local and nonlocal human activities. Despite the intense research efforts over the past two decades, it is still unclear which impact (local or nonlocal) is responsible for the changing flow and sediment characteristics in the estuary. The proposed research, through bring together a group of leading scientists with complementary expertise from China, UK and Netherlands, is designed to achieve a more systematic understanding of the mechanisms by which flow and sediment dynamics in YED tidal channels are affected by anthropogenic activities, and use this insight to formulate effective coastal management strategies.Objectives
We propose to investigate a major problem occurring in the high turbidity zones of the Yangtze Estuarine Delta (YED), viz. the amplification of tides, seaward migration of mouth bars, coarsening of bed sediment, increased siltation in navigation channels and a potential regime shift towards a hyperturbid system resulting from engineering works. Specific objectives are to (1) determine tidal amplification, spatial distribution of flow and suspended sediment in the estuary, under natural processes and in response to human interventions, focusing especially on the effects of narrowing and deepening of channels due to local engineering works and temporal variation of water and sediment supply from the watershed; (2) quantify turbulent mixing and sediment fluxes and to establish the thresholds for the potential regime shift of the delta system towards hyperturbidity; (3) understand the physical mechanisms that determine both the natural behaviour and the response of hydrodynamics and sediment dynamics in the estuarine channels to different types of human activities; (4) propose methods to reduce deposition of sediment in navigation channels and to manage the flood defence, fresh water supply of the YED system.
|Extending:||UK Research & Innovation|
|Funding:||UK - Department for Business, Energy and Industrial Strategy|
|Implementing:||University of Liverpool|
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