Response of Ecologically-mediated Shallow Intertidal Shores and their Transitions to extreme hydrodynamic forcing in UK settings (RESIST-UK)

盐沼遍布全球，分布在低洼、低梯度的沿海边缘地带。在为社会提供许多服务（每年每公顷价值约1,500英镑）的同时，它们因保护海岸免受海浪和潮汐侵蚀的能力而受到重视，即使在极端风暴潮事件期间也是如此。然而，在全国和全球范围内，它们都在减少。在英国，从1945年到2010年，盐沼面积减少了13%（从37,300公顷减少到32,500公顷）。这一损失并没有通过恢复沼泽的努力得到补偿（到2012年仅恢复了1320公顷）。这些天然海岸保护特征（或其人工修复或重建的等同物）将如何应对未来海平面变化和风暴强度和/或频率可能发生的变化的综合影响，这是高度不确定的。盐沼的草/灌木覆盖的表面对风暴的影响表现出明显的抵抗力。如果有足够的沉积物供应，它们还可以“垂直生长”，以追踪海平面的上升。因此，随着时间的推移，沼泽面积的减少往往是由于它们最靠近大海的边缘向陆地退缩，或者是排水的潮汐通道的横向拓宽。这些边界经常被削弱，沼泽物质被潮汐和波浪松动带走。这种退缩每年可能达到几米，这是沿海工程师、规划师和管理者非常关注的问题，他们依赖于这些环境的“风暴缓冲”功能。我们对“切割”盐沼物质（“基质”）所需的力知之甚少。底物本身是由潮汐随时间沉淀的沉积物，以及土壤中植物生长和无脊椎动物产生的有机物质组成的。因此，它对波浪或潮汐力的抵抗力在沼泽内部和沼泽之间是不同的。但是，到目前为止，这种阻力还没有被测量出来，使得海岸工程师在预测未来环境情景的影响时（例如，更大的水深和更强的潮汐或波浪），无法将其考虑在内。在这个项目中，我们将取样并详细分析一个沙质较多的湿地（Warton, Morecambe Bay）和一个泥质较多的湿地（Dengie, Essex）的基质，以及两个恢复的湿地（两个东海岸管理的重新调整地点）及其邻近的自然等效物。我们将确定这些基质是由什么组成的，它们在每个沼泽之间和沼泽内部是如何变化的，以及它们是如何影响沼泽基质对波浪和潮汐力的抵抗力的。最先进的技术（无人驾驶飞行器或“无人机”）和最新的卫星产品将使我们能够绘制出沼泽系统的物理脆弱性地图，包括整个沼泽和沼泽内部，以应对这些类型的力量。沿海规划人员、工程师和管理人员将通过能够更好地预测未来的沼泽损失并设计适当的预防措施而受益。任何观看我们的三集纪录片短片系列的人都将通过更好地理解我们使用的科学方法而受益。国际社会已经在使用基于网络的工具中内置的现有卫星产品来评估盐沼的海岸保护功能，这将受益于我们将在这些工具中内置的对波浪/潮汐侵蚀的抵抗力的预测。

Salt marshes exist around the globe on low-lying, low gradient coastal fringes. Amongst providing many services to society (valued at around £1,500 per hectare per year), they are valued for their ability to protect coasts from the erosive force of waves and tides, even during extreme storm surge events. They are, however, nationally and globally in decline. In the UK, the area of salt marsh reduced by 13% between 1945 and 2010 (from 37,300 to 32,500 ha). This loss has not been compensated for through marsh restoration efforts (only 1,320 ha created by 2012). There is high uncertainty as to how these natural coastal protection features (or their artificially restored or re-created equivalents) will respond to the combined effects of future changes in sea level and possible changes in the magnitude and/or frequency of storms.The grass/shrub covered surfaces of salt marshes appear remarkably resistant to storm impact. Given sufficient sediment supply, they can also 'grow' vertically to track rising sea levels. The loss of marsh area over time is therefore more often due to a landward retreat of their most seaward margin or the lateral widening off the tidal channels that drain them. These boundaries are often undercut, with marsh material loosened and removed by tidal currents and waves. Such retreat may reach several metres per year and is of great concern to coastal engineers, planners, and managers, relying on the 'storm buffering' function of these environments.We know little about the force required to 'cut into' salt marsh material (the 'substrate'). The substrate itself is composed of sediment laid down over time by the tides, alongside organic materials resulting from plant growth and invertebrates living in the soil. Its resistance to wave or tidal forces therefore varies within and between marshes. But this resistance has not, so far, been measured in a way that allows coastal engineers to take it into account when predicting the impact of future environmental scenarios (e.g. greater water depths and stronger tidal currents or waves). In this project, we will sample and analyse in detail the substrate of a more sandy (Warton, Morecambe Bay) and a more muddy (Dengie, Essex) marsh, as well as of two restored marshes (two East coast managed realignment sites) and their adjacent natural equivalents. We will determine what these substrates are composed of, how this varies between and within each of these marshes and how it affects the resistance of the marsh substrate to wave and tidal forces. State-of-the-art technology (unmanned aerial vehicles (UAVs) or 'drones') and the latest satellite products will then allow us to produce a map of the physical marsh vulnerability of marsh systems, both in their entirety and within marsh, to these types of forces. Coastal planners, engineers, and managers will benefit through being able to better predict marsh loss into the future and design suitable preventative measures. Anyone watching our three-part documentary short film series will benefit through a better understanding of the scientific methods we use. The global community already using existing satellite products built into web-based tools for assessing the coastal protection function of salt marshes will benefit by being able to access predictions of the resistance to wave/tide erosion that we will build into those tools.