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

英国环境中生态介导的浅潮间带海岸的响应及其对极端水动力强迫的转变（RESIST-UK）

• 批准号: NE/R01082X/1
• 负责人: Thomas Spencer
• 金额: $ 74.17万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FR01082X%2F1
• 关键词: Response; Ecologically; mediated; Shallow; Intertidal

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.

盐沼存在于全球各地地势低洼、坡度低的沿海边缘。在为社会提供的许多服务中(价值约为每公顷1,500 GB/年)，它们的价值在于它们能够保护海岸免受海浪和潮汐的侵蚀，即使在极端的风暴潮期间也是如此。然而，在全国和全球范围内，它们都在下降。在英国，盐沼面积在1945年至2010年间减少了13%(从37300公顷减少到32500公顷)。这一损失没有通过沼泽恢复努力得到补偿(到2012年只创造了1320公顷)。对于这些天然海岸保护特征(或其人工恢复或重建的等价物)将如何应对未来海平面变化以及可能发生的风暴强度和/或频率变化的综合影响，存在很高的不确定性。盐沼覆盖的草/灌木表面似乎对风暴影响具有显著的抵抗力。如果有足够的沉积物供应，它们还可以垂直生长以跟踪海平面的上升。因此，随着时间的推移，沼泽面积的丧失更多地是由于它们最向海的边缘向陆地的后退，或者是排干它们的潮汐通道的横向加宽。这些边界经常被削弱，沼泽物质被潮流和海浪松动和带走。这种退缩每年可能达到几米，这是沿海工程师、规划者和管理人员非常担心的，依赖于这些环境的“风暴缓冲”功能。我们对‘切割’盐沼物质(‘底物’)所需的力量知之甚少。底物本身由潮汐随着时间推移而沉积的沉积物组成，此外还有植物生长产生的有机物质和生活在土壤中的无脊椎动物。因此，它对波浪或潮汐力量的抵抗力在沼泽地内和沼泽地之间有所不同。但到目前为止，这种阻力还没有被测量到，使沿海工程师在预测未来环境情景(如更大的水深和更强的潮汐或海浪)的影响时能够考虑到这一点。在这个项目中，我们将对沙质较多的沼泽(沃顿，莫克坎贝湾)和泥泞较多(丹吉，埃塞克斯)的沼泽以及两个恢复的沼泽(两个东海岸管理的重新调整地点)及其邻近的自然等价物的底质进行详细的采样和分析。我们将确定这些底物是由什么组成的，这些底物在这些沼泽之间和每个沼泽内部是如何变化的，以及它如何影响沼泽底物对波浪和潮汐作用力的阻力。最先进的技术(无人机或无人机)和最新的卫星产品将使我们能够制作出沼泽系统的物理沼泽脆弱性地图，无论是整个沼泽系统还是沼泽内的沼泽系统，对这些类型的部队都是如此。沿海规划者、工程师和管理人员将受益于能够更好地预测未来的沼泽损失并设计适当的预防措施。任何观看我们三集纪录片短片系列的人都将受益于对我们使用的科学方法的更好理解。已经在使用基于网络的工具评估盐沼海岸保护功能的现有卫星产品的国际社会，将能够获得我们将纳入这些工具的抗海浪/潮汐侵蚀能力的预测，从而受益。

项目成果

Salt marsh and tidal flat shear strength: a comparison between Tillingham marsh, Essex and Warton marsh, Morecambe Bay, UK

盐沼和潮滩剪切强度：埃塞克斯郡蒂林厄姆沼泽和英国莫克姆湾沃顿沼泽之间的比较

• 发表时间: 2019
• 作者: Brooks HY

How strong are salt marshes? Geotechnical properties of coastal wetland soils

盐沼的强度有多强？

• DOI: 10.1002/esp.5322
• 发表时间: 2022
• 期刊: Earth Surface Processes and Landforms
• 影响因子: 3.3
• 作者: Brooks H

GEOTECHNICAL PROPERTIES OF SALT MARSH AND TIDAL FLAT SUBSTRATES AT TILLINGHAM, ESSEX, UK.

英国埃塞克斯郡蒂林厄姆盐沼和潮坪基底的岩土特性。

• DOI: 10.9753/icce.v36.papers.55
• 发表时间: 2018
• 期刊: Coastal Engineering Proceedings
• 作者: Brooks H

Shear strength and erosion resistance of salt marsh substrates: Which method to use?

• DOI: 10.1016/j.ecss.2023.108452
• 发表时间: 2023-07
• 期刊: Estuarine, Coastal and Shelf Science
• 作者: H. Brooks;Iris Moeller;T. Spencer;K. Royse

The influence of grain size and frictional/cohesional shear strength components on UK salt marsh substrate stability

粒度和摩擦/内聚剪切强度分量对英国盐沼基质稳定性的影响

• DOI: 10.5194/egusphere-egu2020-17681
• 发表时间: 2020
• 作者: Brooks H