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

河口三角洲是指水和悬沙运动主要由河流和海洋潮汐输入淡水共同作用的地区。水动力和泥沙动力除了受到这些自然驱动力的驱动外，还经常受到各种不同的人为措施的影响，如航道疏浚、填海造地、河口控水控沙工程以及流域上游的堤坝。这些人类活动可能导致河口水流和悬沙特性的强烈变化。在过去的几十年里，欧洲的许多河口体系(如易北河、EMS、卢瓦尔)都显示出潮差和浊度的增加，这似乎与加深[1]一个河口三角洲体系有关，该体系面临着与欧洲河口相似的问题，即长江口三角洲(YED)。对上个世纪中叶以来收集的野外资料的分析表明，上千年来自然形成的伊犁河口河道和水下三角洲的形态模式有很大的变化。与上面提到的欧洲河口相比，YED的规模要大得多，经历的河流流量也要大得多，而且它受到淡水的强烈季节性变化的影响。此外，它是一个复杂的河口网络，有多个分支，连通航道和复杂的三角洲。河口水沙动力的变化可能是局部和非局部人类活动共同作用的结果。尽管在过去的20年里进行了大量的研究工作，但目前仍不清楚是哪种影响(本地或非本地)导致了河口水沙特征的变化。拟议的研究汇集了一批来自中国、英国和荷兰的具有互补专业知识的顶尖科学家，旨在更系统地了解人类活动影响YED潮汐水道水沙动力学的机制，并利用这一见解制定有效的海岸管理策略。

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.