The Influence of Channel Deepening on Tides, River Discharge Effects, and Storm Surge
The Influence of Channel Deepening on Tides, River Discharge Effects, and Storm Surge
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DOI：
10.1029/2020jc016328
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发表时间：
2021-05
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影响因子：
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通讯作者：
S. Talke;R. Familkhalili;D. Jay
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作者：
S. Talke;R. Familkhalili;D. Jay
16 17 我们结合档案研究、半解析模型和数值模拟来解决以下 18 问题：在潮汐 20 振幅向陆地衰减的低同步、强摩擦河口中，河道几何形状的变化如何改变潮汐特性和洪水 19 动力学？自 1890 年代以来圣约翰河口的记录显示，佛罗里达州杰克逊维尔的潮差已增加了一倍。在河口入口附近，潮汐流量大约增加了一倍22，但潮汐幅度仅增加约6%。模型显示，航运航道 23 深度从 5-6 增加到约 13 m 推动了观察到的变化，而航道缩短 24 和宽度减小等其他因素产生的影响相对较小。潮汐幅度增加有25个空间变量，最大变化距入海口20-25公里；潮汐理论表明 26 振幅的增加大约遵循 x exp(μx)，其中 x 是距 27 海洋的距离，μ 是阻尼系数。潮汐变化是潮汐动态变化的预测因素：28 1898 年和 2017 年测深条件下飓风艾尔玛的数值模型证实 29 如今潮汐和风暴潮的振幅都更大，具有相似的空间模式。 30 尽管如此，根据 1898 年测深结果，模拟的峰值水位会更高。原因 31 很可能是暴风雨期间观察到的创纪录的河流流量；根据潮下水位模型32，自1898年以来河道加深似乎降低了将平均河水流和风暴流排向海洋所需的平均表面坡度33。尽管如此，结果 34 表明河流流量较少但风暴潮较大时，对风暴的脆弱性增加。 35
16 17 We combine archival research, semi-analytical models, and numerical simulations to address the 18 following question: how do changes to channel geometry alter tidal properties and flood 19 dynamics in a hyposynchronous, strongly frictional estuary with a landward decay in tidal 20 amplitudes? Records in the Saint Johns River Estuary since the 1890s show that tidal range has 21 doubled in Jacksonville, Florida. Near the estuary inlet, tidal discharge approximately doubled 22 but tidal amplitudes increased only ~6%. Modeling shows that increased shipping channel 23 depths from 5-6 to ~13m drove the observed changes, with other factors like channel shortening 24 and width reduction producing comparatively minor effects. Tidal amplitude increases are 25 spatially variable, with a maximum change 20-25 km from the estuary inlet; tidal theory suggests 26 that increases in amplitude approximately follow x exp(μx), where x is the distance from the 27 ocean and μ is a damping coefficient. Tidal changes are a predictor of altered surge dynamics: 28 Numerical modeling of hurricane Irma under 1898 and 2017 bathymetric conditions confirms 29 that both tidal and storm surge amplitudes are larger today, with a similar spatial pattern. 30 Nonetheless, peak water levels are simulated to be larger under 1898 bathymetry. The cause is 31 likely the record river discharge observed during the storm; as suggested by a subtidal water32 level model, channel deepening since 1898 appears to have reduced the average surface slope 33 required to drain both mean river flow and storm flows towards the ocean. Nonetheless, results 34 suggest an increased vulnerability to storms with less river flow, but larger storm surge. 35