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沿海盐沼的形态发展沿着潮汐影响的海岸如何响应预期的未来全球海平面上升（SLR）和风暴活动的可能变化。先前的研究表明，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的SLR情景下可能会消失。潮差和沉积物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。它在很大程度上取决于外来沉积物来源，例如来自河流沉积物输入和海岸侵蚀，以及当地的潮间带沉积物动态，这些沉积物动态具有很大的时空变异性，而且发生在沿海盐沼附近。在很大程度上，在当地的沉积物特性和风暴活动的时间变化负责的变化，沉积物输送到盐沼。拟议项目的主要假设是，沿海盐沼的未来发展的预测受到沉积物可用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的沉积物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在当地的风暴气候的变化，诱导增加水动力能沿着海岸和潮间带，因此，增加泥沙输运。一个特别的重点放在波浪和水流的影响，以及普遍的水位，可能会控制沉积物的数量被供应到沿海盐沼。将开展广泛的实地活动，以收集关于Freiston海岸（英国东海岸）示例研究地点的主要沉积物动力学的数据，该研究地点先前已由主办机构进行了广泛的调查。将采用各种最先进的测量装置，监测近场外部沉积物供应、潮间带沉积物动态以及由此产生的沼泽沉积物供应，为期一年。收集的数据将被用来开发一个耦合盐沼模型，模拟风暴活动的十年变化如何影响盐沼的沉积物供应及其垂直增长。模拟运行将使用广泛的海平面上升（SLR）和风暴气候情景，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.