Rapid Response: Morphological Change Near Katama Inlet During Hurricane Sandy

知识专长：飓风桑迪在科德角以南的大陆架上产生了66米水深的11米高的波浪，在马萨诸塞州玛莎葡萄园岛南部海岸离岸2公里处产生了12米水深的5米高的波浪。大浪与强大的潮汐和波浪驱动的水流相结合，可以将大量的沉积物沿着海岸线输送，并在涨潮时进入入口。飓风桑迪过后对卡塔马湾和入口的目视检查表明，退潮浅滩、海岸线、入口和后湾发生了很大变化。 将对Katama入口附近的退潮浅滩、入口通道和后湾进行桑迪后调查。当与桑迪前的调查和调查人员在飓风桑迪之前、期间和之后收集的潮汐、波浪和海流的观测相结合时，拟议的观测将允许使用数据和数值模型来解决以下假设：（i）风暴相对于潮落和洪水的时间对形态演变很重要，以及（ii）海湾内的淤积是由从西部沿岸携带的沙子造成的，随后在洪水期间被输送到入口。假设波浪辐射应力将水驱入海湾，产生更强的洪水和更弱的落潮，在风暴期间进一步增强沉积物向海湾的输送。更广泛的影响：项目调查人员一直在为当地港务长、划船组织和贝壳渔民提供最新的水深图，以帮助他们开展业务。随着入口的发展，对影响形态的过程的更好理解和数值模型将有助于他们做出未来的管理决策。例如，美国陆军工程兵部队已经调查了卡塔马湾和大西洋之间的可持续突破，以防止海湾商业牡蛎养殖场的淤积，这可能会给当地的贝类捕捞业带来每年数百万美元的收益。此外，本研究的结果将帮助港务长随着入口的演变和埃德加敦港水流的变化而规划运营。此外，经现场验证的入口演变建模系统可用于模拟一系列近岸系统，允许在其他领域进行模拟和假设情景。此外，WHOI-MIT的三名博士生将使用这些观测结果作为他们关于波浪对海岸线形态演变和入口流影响的论文研究的一部分。

Intellectual Merit:Hurricane Sandy produced 11-m high waves in 66-m water depth on the continental shelf south of Cape Cod and 5-m high waves in 12-m depth 2 km offshore of the southern shore of Martha's Vineyard, MA. The large waves combined with strong tidal- and wave-driven currents can transport tremendous amounts of sediment along the shoreline, and into the inlet during flood tides. Visual inspection of Katama Bay and Inlet after Hurricane Sandy suggest there were large changes to the ebb shoal, shoreline, inlet, and back bay. A post-Sandy survey of the ebb shoal, inlet channel, and back bay near Katama Inlet will be conducted. When combined with the pre-Sandy survey and observations of tides, waves, and currents that were collected by the investigators before, during, and after Hurricane Sandy, the proposed observations will allow the data and numerical models to be used for addressing the following hypotheses:(i) the timing of storms relative to ebb and flood flows is important to the morphological evolution, and(ii) accretion inside the bay is caused by sand carried alongshore from the west and subsequently transported into the inlet during flood flows.An additional hypothesis is that wave radiation stresses drive water into the inlet, producing stronger flood and weaker ebb flows, further enhancing the transport of sediment into the inlet during storms.Broader Impacts:The project investigators have been providing the local harbormaster, boating organizations, and shell fishermen with updated bathymetric maps to help them with their operations. Improved understanding of, and numerical models for, the processes affecting the morphology would help them with future management decisions as the inlet evolves. For example, the US Army Corps of Engineers has investigated establishing a sustainable breach between Katama Bay and the Atlantic to prevent siltation of the commercial oyster farms in the bay, potentially resulting in several million dollars per year of benefit to the local shell fishing industry. In addition, the results from this study will help harbormasters plan operations as the inlet evolves and currents change in Edgartown Harbor. Moreover, a field-verified modeling system of inlet evolution can be used to simulate a range of nearshore systems, allowing simulations and what-if scenarios in other areas. In addition, the observations will be used by three WHOI-MIT PhD students as part of their dissertation research about the effects of waves on shoreline morphological evolution and on inlet flows.