摘要：The interaction between physical drivers fromoceanographic, hydrological, and meteorological processes in coastal areascan result in compound flooding. Compound flood events, like Cyclone Idaiand Hurricane Harvey, have revealed the devastating consequences of theco-occurrence of coastal and river floods. A number of studies have recentlyinvestigated the likelihood of compound flooding at the continental scalebased on simulated variables of flood drivers, such as storm surge,precipitation, and river discharges. At the global scale, this has only beenperformed based on observations, thereby excluding a large extent of theglobal coastline. The purpose of this study is to fill this gap and identifyregions with a high compound flooding potential from river discharge andstorm surge extremes in river mouths globally. To do so, we use dailytime series of river discharge and storm surge from state-of-the-art globalmodels driven with consistent meteorological forcing from reanalysisdatasets. We measure the compound flood potential by analysing bothvariables with respect to their timing, joint statistical dependence, andjoint return period. Our analysis indicates many regions that deviate fromstatistical independence and could not be identified in previous globalstudies based on observations alone, such as Madagascar, northern Morocco,Vietnam, and Taiwan. We report possible causal mechanisms for the observedspatial patterns based on existing literature. Finally, we providepreliminary insights on the implications of the bivariate dependencebehaviour on the flood hazard characterisation using Madagascar as a casestudy. Our global and local analyses show that the dependence structurebetween flood drivers can be complex and can significantly impact the jointprobability of discharge and storm surge extremes. These emphasise the needto refine global flood risk assessments and emergency planning to accountfor these potential interactions.
