Land use or land-use changes can trigger or generate hazards and affect the potential consequences of these hazards. Deforestation can trigger land slides, for example, and land reclamation or levee construction can increase flood hazards downstream. New dwellings in or near forests can trigger wildfires, especially if home owners fail to prioritise fire safety measures. In addition, if land is used for industrial activities, new technological hazards, such as the risks resulting from the storage or production of hazardous materials, can be introduced into the environment. Moreover, land-use changes can increase damage potential. Residential developments in hazard-prone areas, such as areas prone to flooding or earthquakes, can negatively affect the number of properties and people exposed to hazards. Consequently, spatial planning activities that are concerned with influencing land use by locating physical structures and activities such as agriculture, recreation or industry within a territory (Couclelis, 2005; Tewdwr-Jones, 2001) can result in new or increased safety risks in a particular area.
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'Versteende pleinen in steden zijn hitte-eilanden. Gemeenten willen daarom meer groen, maar dat is niet eenvoudig. In Groningen zijn nieuwe bomen geplant in een innovatief waterbergingssysteem. De Grote Markt ging op de schop.'
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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 reanalysis 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.
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