Impacts of temporal variations in sediment availability on the long-term ability of coastal salt marshes to adapt to global sea level rise

拟议的项目旨在调查受潮汐影响的海岸沿岸盐沼的形态发展如何对预期的未来全球海平面上升和风暴活动可能发生的变化作出反应。以前的研究表明，世界上大多数地方的沿海盐沼能够适应低和中等SLR情景，但在不断加速或非常高SLR情景下可能会消失。潮差和泥沙供应已被确定为影响沿海盐沼适应海平面上升能力的最重要参数。沉积物供应是沿海环境中发生的一系列复杂相互作用的结果。它严重依赖外部泥沙来源，例如来自河流泥沙输入和海岸侵蚀的外部泥沙来源，以及当地潮间带泥沙动力，这些泥沙动力具有很大的时空变异性，发生在沿海盐沼附近。在很大程度上，当地泥沙特性和风暴活动的时间变化是盐沼泥沙输送变化的原因。拟议项目的主要假设是，对沿海盐沼未来发展的预测受到泥沙可获得性的时间变化的强烈影响。该项目旨在调查近场外部沉积物供应和潮间带沉积物动力学的时间变化如何影响沼泽地的泥沙供应及其未来的长期发展。这种时间变化的主要驱动力被认为是当地风暴气候的变化，导致沿海岸和潮间带的水动力能量增加，从而增加了沉积物的输运。特别关注海浪和海流的影响，以及可能控制向沿海盐沼提供泥沙数量的普遍水位。将开展一次广泛的实地活动，以收集关于弗雷斯顿海岸(英国东海岸)范例研究地点的主要沉积物动力学数据，主办机构以前曾对该地点进行过广泛调查。将使用各种最先进的测量设备来监测近场外部泥沙供应、潮间带滩涂的泥沙动态以及由此产生的湿地泥沙供应，为期一年。收集的数据将用于开发盐沼耦合模型，以模拟风暴活动的年代际变化如何影响盐沼的泥沙供应及其垂直生长。将使用广泛的海平面上升(SLR)和风暴气候情景进行模拟运行，以评估这些变化如何影响沿海盐沼适应未来SLR的能力。

The proposed project aims to investigate how the morphological development of coastal salt marshes along tidally influenced coasts responds to the expected future global sea level rise (SLR) and possible changes in storm activity. Previous research has shown that coastal salt marshes in most places around the world are able to adapt to low and moderate SLR scenarios but will likely disappear under constantly accelerating or very high SLR scenarios. Tidal range and sediment supply have been identified as the most important parameters affecting the adaptive capacity of coastal salt marshes to rising sea levels. Sediment supply is the result of a chain of complex interactions taking placing in the coastal environment. It strongly depends on external sediment sources, originating from riverine sediment input and coastal erosion, for example, and local intertidal sediment dynamics, which are subject to large temporal and spatial variability and take place in close vicinity of the coastal salt marshes. To a large extent, temporal variations in local sediment characteristics and storm activity are responsible for the variability in sediment delivery to the salt marshes. The major hypothesis of the proposed project is that predictions for the future development of coastal salt marshes are strongly influenced by temporal variations of sediment availability. The project aims to investigate how temporal variations in the near-field external sediment supply and the intertidal sediment dynamics influence the sediment supply of the marshes and their future long-term development. The major driver for such temporal variations is assumed to be changes in the local storm climate, inducing increased hydrodynamic energy along the coast and on the intertidal flats, hence, increased sediment transport. A special focus is put on the impact of waves and currents as well the prevailing water level that may control the amount of sediment being supplied to the coastal salt marshes. An extensive field campaign will be conducted to collect data on the prevailing sediment dynamics at the example study site Freiston Shore (UK East coast), which has previously been extensively investigated by the host institution. A wide range of state-of-the-art measurement devices will be employed to monitor the near-field external sediment supply, the sediment dynamics on the intertidal flat, and the resulting sediment supply of the marsh for a period of one year. The collected data will be used to develop a coupled salt-marsh model for simulating how decadal variations in storm activity affect the sediment supply of the salt marsh and its vertical growth. Simulation runs will be performed using a wide range of sea level rise (SLR) and storm climate scenarios to assess how these changes influence the ability of coastal salt marshes to adapt to future SLR.