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

河口三角洲是河流淡水输入和潮汐共同驱动水沙运动的区域。水动力和沉积物动力除了受这些自然强迫因子的驱动外，还经常受到各种不同的人为措施的影响，如河道疏浚、土地复垦、河口的水流和沉积物控制工程以及流域上游的水坝。这些人类活动可能导致河口水流和悬沙行为的强烈变化。在过去的几十年里，欧洲的许多河口系统（如易北河、埃姆斯河、卢瓦尔河）都表现出潮差和浊度的增加，这似乎与加深有关[1]长江口三角洲（YED）是面临与欧洲河口类似问题的河口三角洲系统。自上个世纪中期以来收集的现场数据分析表明，有显着的变化，在形态模式的河口通道，以及水下三角洲的YED是自然产生的超过千年的时间。与上述欧洲河口相比，YED的规模更大，经历了更强的河流流量，并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，具有多个分支，连接通道和复杂的三角洲。河口水沙动力的变化可能是本地和非本地人类活动共同作用的结果。尽管在过去二十年中进行了大量的研究，但仍不清楚哪些影响（本地或外地）对河口水流和沉积物特性的变化负有责任。拟议的研究通过汇集来自中国、英国和荷兰的一批具有互补专业知识的领先科学家，旨在更系统地了解YED潮汐通道中的水流和沉积动力学受人类活动影响的机制，并利用这一洞察力来制定有效的沿海管理战略。

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.