Observations and a linear model of water level in an interconnected inlet‐bay system
Observations and a linear model of water level in an interconnected inlet‐bay system
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互连进水湾系统中水位的观测和线性模型
DOI：
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发表时间：
2017
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通讯作者：
R. Signell
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作者：
A. Aretxabaleta;N. Ganju;B. Butman;R. Signell
沿着长岛南部、纽约和世界各地的许多沿海地区都有堰洲岛和堰后海湾系统。描述海湾对水位波动的物理响应是了解极端事件中的洪水并评估其与地貌变化的关系所必需的。离岸海平面是半封闭障壁后海湾水位波动的主要驱动力之一。我们分析了观测到的水位（2007年10月至2015年11月），并开发了分析模型，以更好地了解长岛南部沿着的海湾水位。2014年年中，在大南湾观察到主导M2潮汐振幅（包含最大部分的变化）增加（0.17米振幅中的0.02米变化）。观测到的潮汐振幅和海湾水位从海上转移的变化与附近入口的疏浚有关，可能与飓风桑迪（2012年12月后）造成的火岛缺口大小的变化有关。海湾响应与波动的幅度无关（例如，在特定的频率。一个分析模型，结合海湾和入口尺寸再现了在大南湾和周边地区观察到的传递函数。该模型预测的传递函数Moriches和Shinnecock海湾的长期观测不可用。该模型是一个简化的工具，调查海湾水位的变化，并使未来的条件和替代地貌设置的评估。我们分析了长岛南部海湾（牙买加湾、大南湾和相连海湾）的水位观测结果，以确定海湾如何对开阔海洋的条件作出反应。我们特别关注潮汐的时间变化和对风暴的反应。近年来（2008-2015年），潮汐和与近海的水位关系略有变化。这些变化有时发生在入口疏浚期间或之后，也是飓风桑迪造成的火岛裂口尺寸变化的结果。我们提出了一个简单的模型，考虑到入口和海湾的尺寸和摩擦的入口通道预测水位响应的潮汐和风暴在所有海湾，包括那些长期观测数据不可用。
A system of barrier islands and back-barrier bays occurs along southern Long Island, New York, and in many coastal areas worldwide. Characterizing the bay physical response to water level fluctuations is needed to understand flooding during extreme events and evaluate their relation to geomorphological changes. Offshore sea level is one of the main drivers of water level fluctuations in semienclosed back-barrier bays. We analyzed observed water levels (October 2007 to November 2015) and developed analytical models to better understand bay water level along southern Long Island. An increase ( 0.02 m change in 0.17 m amplitude) in the dominant M2 tidal amplitude (containing the largest fraction of the variability) was observed in Great South Bay during mid-2014. The observed changes in both tidal amplitude and bay water level transfer from offshore were related to the dredging of nearby inlets and possibly the changing size of a breach across Fire Island caused by Hurricane Sandy (after December 2012). The bay response was independent of the magnitude of the fluctuations (e.g., storms) at a specific frequency. An analytical model that incorporates bay and inlet dimensions reproduced the observed transfer function in Great South Bay and surrounding areas. The model predicts the transfer function in Moriches and Shinnecock bays where long-term observations were not available. The model is a simplified tool to investigate changes in bay water level and enables the evaluation of future conditions and alternative geomorphological settings. Plain Language Summary We analyze water level observations in the bays of southern Long Island (Jamaica Bay, Great South Bay and connected bays) to determine how the bays respond to the conditions in the open ocean. We focus especially on changes in time in the tides and in the response to storms. The tides and the water level relationship with offshore have been changing slightly in recent years (2008–2015). The changes occur at times during or immediately after inlet dredging and also as a result of the changing dimensions of a breach through Fire Island caused by Hurricane Sandy. We propose a simple model that takes into account the inlet and bay dimensions and friction in the inlet channels to predicts water level response to tides and storms in all bays including those for which long-term observational data were not available.