Sea-level rise due to anthropogenic climate change is projected not only to exacerbate extreme events such as cyclones and storms but also to cause more frequent chronic flooding occurring at high tides under calm weather conditions. Chronic flooding occasionally takes place today in the low-lying areas of the Petit Cul-de-sac marin (Guadeloupe, West Indies, French Antilles). This area includes critical industrial and harbor and major economic infrastructures for the islands. As sea level rises, concerns are growing regarding the possibility of repeated chronic flooding events, which would alter the operations at these critical coastal infrastructures without appropriate adaptation. Here, we use information on past and future sea levels, vertical ground motion, and tides to assess times of emergence of chronic flooding in the Petit Cul-de-sac marin. For RCP8.5 (Representative Concentration Pathway 8.5; i.e., continued growth of greenhouse gas emissions), the number of flood days is projected to increase rapidly after the emergence of the process so that coastal sites will be flooded 180 d a year within 2 decades of the onset of chronic flooding. For coastal locations with the lowest altitude, we show that the reconstructed number of floods is consistent with observations known from a previous survey. Vertical ground motions are a key source of uncertainty in our projections. Yet, our satellite interferometric synthetic-aperture radar results show that the local variability in this subsidence is smaller than the uncertainties in the technique, which we estimate to be between 1 (standard deviation of measurements) and 5 mm/yr (upper theoretical bound). Despite these uncertainties, our results imply that adaptation pathways considering a rapid increase in recurrent chronic flooding are required for the critical port and industrial and commercial center of Guadeloupe. Similar processes are expected to take place in many low-elevation coastal zones worldwide, including on other tropical islands. The method used in this study can be applied to other locations, provided tide gauge records and local knowledge of vertical ground motions are available. We argue that identifying times of emergence of chronic flooding events is urgently needed in most low-lying coastal areas, because adaptation requires decades to be implemented, whereas chronic flooding hazards can worsen drastically within years of the first event being observed.

中文翻译：

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瓜德罗普岛主要经济中心发生慢性洪水的时间表

预计由于人为气候变化引起的海平面上升不仅加剧诸如旋风和暴风雨之类的极端事件，而且还导致在平静的天气条件下在涨潮时发生更频繁的慢性洪水。今天，有时在Petit Cul-de-sac marin的低洼地区（瓜德罗普岛，西印度群岛，法属安的列斯群岛）偶尔发生洪水。该区域包括岛屿的关键工业和港口以及主要经济基础设施。随着海平面上升，人们越来越关注反复发生的长期洪灾事件的可能性，这将改变这些关键沿海基础设施的作业，而无需进行适当的调整。在这里，我们使用有关过去和将来的海平面，垂直地面运动，并评估在Petit Cul-de-sac marin中发生长期洪水的时间。对于RCP8.5（代表性浓度途径8.5；即温室气体排放量的持续增长），预计洪水天数在该过程出现后将迅速增加，以便沿海地区将在20年后的180年内被洪水淹没。慢性水灾的发作。对于海拔最低的沿海地区，我们表明洪水的重建数量与先前调查中发现的观测值一致。垂直地面运动是我们预测中不确定性的关键来源。然而，我们的卫星干涉合成孔径雷达结果表明，这种沉降的局部变化小于该技术的不确定性，我们估计在1（测量的标准偏差）和5 mm / yr（理论上限）之间。尽管存在这些不确定因素，但我们的结果表明，瓜德罗普岛的关键港口和工商业中心都需要考虑经常性慢性洪灾迅速增加的适应途径。预计在世界范围内许多低海拔沿海地区，包括在其他热带岛屿上，也会发生类似的过程。只要潮汐计记录和垂直地面运动的本地知识可用，本研究中使用的方法可以应用于其他位置。我们认为，在大多数低洼的沿海地区，迫切需要确定慢性洪水事件的发生时间，因为适应工作需要数十年的时间来实施，