High‐Tide Flooding Along the China Coastline: Past and Future
High‐Tide Flooding Along the China Coastline: Past and Future
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DOI：
10.1029/2022ef003225
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发表时间：
2023-04
期刊：
影响因子：
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通讯作者：
S. Li;T. Wahl;J. Fang;Li-Yu Daisy Liu;T. Jiang
中科院分区：
文献类型：
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作者：
S. Li;T. Wahl;J. Fang;Li-Yu Daisy Liu;T. Jiang
海岸洪水已成为中国低洼沿海城市的一个主要问题，大量研究集中在评估风暴及相关极端海平面带来的洪水风险。然而，高潮洪水（HTF）虽导致较小规模的淹没且随着海平面持续上升发生得更为频繁，但尚未得到全面评估。在此，我们利用验潮仪记录分析中国沿海的高潮洪水。我们发现高潮洪水的发生频率有所增加（厦门每11.5 - 37.4年高潮洪水频率就会翻倍，中位数为17.5年）。结果是，在一些地方，高潮洪水的累积损失率高于重大（或极端）洪水事件。为深入了解驱动高潮洪水变化的过程，我们将高潮洪水期间出现的静水水位分解为五个组成部分，包括非线性趋势、年际到年代际平均海平面（MSL）变化、季节性平均海平面周期、潮汐异常和非潮汐残差。很明显，由于海平面上升（SLR），更少的组成部分需要结合就能使水位升高到高潮洪水阈值之上。我们发现南海海岸已经出现了完全由大潮驱动的高潮洪水，并且未来仅由潮汐引发的高潮洪水事件数量也将增长最快。总体而言，在所有变暖情景下，随着海平面上升，中国将经历更多的高潮洪水天数。这一长期趋势将受到海洋潮汐的交点周期的调节，导致在21世纪30年代和50年代高潮洪水更快速地增加。
Coastal flooding has become a major issue for low‐lying coastal cities in China, and a lot of research has focused on assessing flood risk from storms and associated extreme sea levels. High‐tide flooding (HTF), however, which leads to minor inundation and occurs more frequently as sea level continues to rise has not been assessed comprehensively. Here, we analyze HTF along the China coastline using tide gauge records. We show that the frequency of HTF has increased (Xiamen doubled HTF frequency every 11.5–37.4 years, with the median being 17.5 years). As a result, the cumulative loss ratios of HTF are higher than those of major (or extreme) flooding events in several locations. To gain insights into the processes driving HTF changes, we decompose still water levels that occurred during HTF into five components, including non‐linear trend, interannual to decadal mean sea level (MSL) variability, seasonal MSL cycle, tidal anomaly, and nontidal residuals. It is evident that due to sea‐level rise (SLR) fewer components need to combine to raise the water levels above HTF thresholds. We show that the South China Sea coast already experiences HTF purely driven by high spring tides, and will also see the fastest future increase in the number of tide‐only HTF events. In general, China will experience more HTF days under all warming scenarios as SLRs. This long‐term trend will be modulated by the nodal cycle of ocean tides leading to more rapid increases in HTF in the 2030s and 2050s.