CNH: Drowning of Developed Coastal Barriers: Investigating the Threshold Rates of Sea-Level Rise of the Geologic-Human System

沿海屏障，沿着世界上许多海岸发现的狭窄的沙岛或吐槽，在下个世纪面临着不确定的未来。海平面上升的速度已经超过了过去几千年的速度，预计到本世纪末海平面上升的速度还会大大加快，从而有可能造成屏障被淹没。天然屏障通过向陆地迁移的过程对海平面上升作出反应——在风暴期间，冲积和破裂将沉积物转移到屏障的背面。人类活动旨在保护沿海基础设施，如建造海堤，建造石坝，滋养海滩，稳定进水口，或装甲上浮岬角，已经积累到一个新的地形，在地球上前所未有的地步。美国历史上，已经出现了：“发达障碍”。通常，在已开发的屏障上进行的工程活动可以防止或抵消过度冲刷。指导这项研究的两个关键问题是：1)是否存在海平面上升的阈值，超过这个阈值，海岸屏障就会完全淹没？2)人类对海平面上升的反应是否会减轻或加剧整个系统中已开发屏障丧失的可能性？一个由地质学家、数值建模师和经济学家组成的多学科团队将参与综合领域和建模研究，以检查屏障系统的行为并预测其命运。重点地质调查将调查过去海平面上升的速度（与本世纪末预测的速度相符）对屏障的反应。数值模式将通过耦合自然泥沙搬运过程和海岸的人为改变，研究发达屏障系统在年代际到百年时间尺度上的演变。将探讨不同的人类保护策略，比较协调与不协调的反应，并考虑信息灵通与信息贫乏的反应是否会导致不同的屏障未来。最重要的问题将是，旨在保护基础设施和海滩娱乐的人类活动是否更有可能导致屏障系统的大规模崩溃或“淹没”。由于海平面上升，屏障海滩被淹没是一个具有全球重要性的问题。随着海平面的上升，造成这些屏障的海浪过程也会使它们发生巨大变化。障碍物不仅仅是被动地泛滥（像浴缸一样）；风暴、海浪和潮汐可以重塑整个海岸线。屏障包含一个海滩，这是一种特别有价值的资源，并容纳了大量的基础设施，包括住宅、度假村、酒店和道路。因此，人类通过推平海滩、抽沙和武装海岸来应对海岸的变化。这些活动对海岸自然过程的长期影响是什么？这项研究旨在提供关于全球屏障系统如何应对海平面变化和缓解战略变化的准则，目标是确定最佳社会应对措施，以减少由此造成的潜在经济损失。这项研究将涉及与利益相关者和沿海管理人员的沟通，以获得他们的投入，帮助制定和评估模型模拟的决策策略，并传播研究结果。该计划还将为学生提供跨学科的培训，他们是下一代沿海研究人员，了解沿海过程的各个方面。

AbstractCoastal barriers, narrow sandy islands or spits found along many of the world's coasts, face an uncertain future over the next century. Rates of sea-level rise already exceed those experienced over the last several thousand years and are predicted to be substantially greater by the end of the century, offering the potential that barriers could drown. Natural barriers respond to sea-level rise through a process of landward migration - during storms, overwash and breaching transfer sediment to the back of a barrier. Human activities intended to preserve coastal infrastructure, such as building seawalls, constructing groynes, nourishing beaches, stabilizing inlets, or armoring updrift headlands, have accumulated to the point where a new landform, unprecedented in earth?s history, has emerged: the "developed barrier". Typically, engineering activities on developed barriers prevent or counteract overwash. Two key questions guide this research: 1) Are there threshold rates of sea-level rise beyond which coastal barriers will drown completely? and 2) Will human responses to sea-level rise mitigate or exacerbate the potential for losses of developed barriers across entire systems? A multidisciplinary team of geologists, numerical modelers, and economists will engage in an integrated field and modeling study to examine the behavior and predict the fate of barrier systems. Focused geologic investigations will investigate how barriers responded to higher rates of sea-level rise in the past (rates that match those predicted for later this century). Numerical models will study the evolution of developed barrier systems at decadal to centennial time scales by coupling natural sediment transport processes and human alterations of the coast. Different human protection strategies will be explored, comparing coordinated versus uncoordinated responses and considering whether well-informed versus poorly informed responses result in different barrier futures. The most important question will be whether human activities intended to preserve infrastructure and beach recreation may make wholesale collapse, or "drowning" of barrier systems more likely.The drowning of barrier beaches due to sea-level rise is an issue of global importance. The same wave processes that created these barriers will cause them to change dramatically as sea levels rise. Barriers will do more than flood passively (like a bath tub); storms, waves, and tides can reshape entire coastlines. Barriers contain a beach, a resource that is particularly valued, and house significant amounts of infrastructure, including homes, resort complexes, hotels, and roadways. Accordingly, humans respond to coastal changes by bulldozing beaches, pumping sand, and armoring the coast. What are the long-term effects of these activities on the naturally occurring processes on the coast? This research aims to provide guidelines on how the global system of barriers will respond to changes in sea level and to changes in mitigation strategies, with a goal of identifying optimal societal responses to reduce the resulting potential economic losses. This research will involve communication with stakeholders and coastal managers to obtain their inputs to help formulate and assess decision-making strategies for model simulations and to disseminate the study findings. This program will also provide interdisciplinary training for students, who are the next generation of coastal researchers, on the diverse aspects of coastal processes.