Newton Fund - Natural versus anthropogenically driven behaviour of hydrodynamics and sediment dynamics in Yangtze Estuarian Delta

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[1]

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.

The overall purpose of the proposal is to improve understanding and predictions of coastal river delta evolution together with associated risk and hazards (or benefits) to navigation channels, eaches and wide coastal zones.

The principal beneficiaries of the improved understanding achieved in this project are: land usrs-owners / farmers, coastal dwellers, businesses, Port Authorities, Renewable Operators and the wider population using coastal infrastructure in both China and Europe. National governments and agencies such as the Marine Management Organisation (MMO), Crown Estate, Local Authorities, Environment Agencies as well as consulting engineers will benefit from an improved modelling basis for advice on coastal estuarine delta management strategies, development of Shoreline Management Plans (SMPs) and more cost effective design of engineering intervention schemes.

The consistent approach to morphological prediction and subsequent geomorphological assessment in the proposal emphasises the understanding of geomorphological processes on a range of timescales and spatial scales. This contextualisation enhances the ability to validate models of long-term geomorphic change within the perspective of local change and helps to establish the interrelationships between geomorphological context and the major risks/benefits associated with the morphological changes as the results of either climate change or anthropogenic effects.