Measuring compound flood potential from river discharge and storm surge extremes at the global scale
Measuring compound flood potential from river discharge and storm surge extremes at the global scale
复制标题
从全球尺度的河流流量和风暴潮极端测量复合洪水潜力
DOI：
10.5194/nhess-20-489-2020
复制
发表时间：
2020-02-21
影响因子：
4.6
通讯作者：
Ward, Philip J.
中科院分区：
文献类型：
--
作者：
Couasnon, Anais;Eilander, Dirk;Ward, Philip J.
来自沿海地区海洋、水文和气象过程的物理驱动因素之间的相互作用可能导致复合洪水。复合洪水事件，如飓风Idai和飓风Harvey，揭示了沿海和河流洪水同时发生的破坏性后果。最近，一些研究调查了在大陆尺度上的复合洪水的可能性的基础上模拟变量的洪水驱动器，如风暴潮，降水和河流流量。在全球范围内，这只是根据观测进行的，因此排除了全球大部分海岸线。本研究的目的是填补这一空白，并确定区域的高复合洪水的潜力，从河流排放和风暴潮极端河口全球。为此，我们使用来自最先进的全球模型的河流流量和风暴潮的每日时间序列，这些模型由再分析数据集的一致气象强迫驱动。我们通过分析这两个变量的时间，联合统计依赖性和联合重现期来测量复合洪水潜力。我们的分析表明，许多地区偏离了统计独立性，无法在以前的全球研究中单独根据观察来确定，如马达加斯加，北方摩洛哥，越南和台湾。我们报告可能的因果机制所观察到的空间格局的基础上现有的文献。最后，我们提供了初步的见解的影响，双变量依赖行为的洪水灾害特性，马达加斯加作为一个案例研究。我们的全球和本地分析表明，洪水驱动因素之间的依赖结构可能是复杂的，可以显着影响联合概率的排放和风暴潮极端。这些都强调需要完善全球洪水风险评估和应急规划，以考虑这些潜在的相互作用。
The interaction between physical drivers from oceanographic, hydrological, and meteorological processes in coastal areas can result in compound flooding. Compound flood events, like Cyclone Idai and Hurricane Harvey, have revealed the devastating consequences of the co-occurrence of coastal and river floods. A number of studies have recently investigated the likelihood of compound flooding at the continental scale based on simulated variables of flood drivers, such as storm surge, precipitation, and river discharges. At the global scale, this has only been performed based on observations, thereby excluding a large extent of the global coastline. The purpose of this study is to fill this gap and identify regions with a high compound flooding potential from river discharge and storm surge extremes in river mouths globally. To do so, we use daily time series of river discharge and storm surge from state-of-the-art global models driven with consistent meteorological forcing from re-analysis datasets. We measure the compound flood potential by analysing both variables with respect to their timing, joint statistical dependence, and joint return period. Our analysis indicates many regions that deviate from statistical independence and could not be identified in previous global studies based on observations alone, such as Madagascar, northern Morocco, Vietnam, and Taiwan. We report possible causal mechanisms for the observed spatial patterns based on existing literature. Finally, we provide preliminary insights on the implications of the bivariate dependence behaviour on the flood hazard characterisation using Madagascar as a case study. Our global and local analyses show that the dependence structure between flood drivers can be complex and can significantly impact the joint probability of discharge and storm surge extremes. These emphasise the need to refine global flood risk assessments and emergency planning to account for these potential interactions.