Compound Flooding Dynamics in Coastal Environments

Compound flooding occurs when multiple drivers—such as storm surge, high river discharge, heavy rainfall, tides and waves—coincide or interact to produce extreme inundation in coastal areas. These interactions can overwhelm flood defences and drainage systems more severely than individual hazards acting alone. Coastal environments are particularly vulnerable where low-lying topography, urban development and altered land use intensify flood propagation. Modelling and forecasting compound events demand the integration of hydrodynamic solvers with statistical dependence frameworks, while accounting for uncertainties in climate projections, catchment response and coastal processes. As sea levels rise and storm patterns shift under climate change, understanding the physical mechanisms and statistical relationships that underlie compound floods is essential for global risk assessment, early warning systems and adaptive management strategies in both mega-cities and smaller estuarine communities.

Research from Nature Portfolio

Recent studies have applied decision science to dynamic planning of flood defences in rapidly evolving coastal megacities. By combining multiple flood sources—tidal levels, river flows, rainfall intensity and projected sea-level rise—into a regret-based economic framework, adaptive pathways are defined that trigger interventions when predetermined tipping points are reached. This approach yields “no-regret” strategies that balance investment and risk under deep uncertainty. In parallel, advances in computational modelling now allow ocean surge and inundation dynamics to be simulated in one step using open-source solvers. A globally consistent application to tropical cyclones demonstrates improved skill in reproducing observed flood extents compared to static or two-step approaches, while maintaining computational efficiency. Such process-based models open new avenues for large-scale coastal risk assessments and scenario testing under future climate trajectories.

Compound Flooding Dynamics in Coastal Environments publication trend

The graph below shows the total number of articles in compound flooding dynamics in coastal environments across all publications each year (not limited to Nature Index journals).

Technical terms

Compound flooding: The co-occurrence or interaction of two or more flood drivers (e.g. storm surge and heavy rainfall) leading to amplified inundation.

Storm surge: A rise in coastal water level caused by low atmospheric pressure and wind stress during storms.

Pluvial flooding: Inundation resulting directly from intense rainfall overwhelming urban drainage or soil infiltration capacity.

Fluvial flooding: Overflow of rivers and streams due to elevated river discharge, often from sustained or heavy precipitation.

Joint probability: The likelihood that two or more events (such as extreme surge and river discharge) occur simultaneously or in close succession.

Dynamic adaptation pathways: A decision-making framework that sequences interventions over time, triggering actions when changing conditions reach predefined thresholds.

Process-based modelling: Simulation approaches that explicitly represent physical mechanisms (e.g. hydrodynamics and sediment transport) rather than relying solely on statistical relationships.

References

1. Dynamic adaptive engineering pathways for mitigating flood risks in Shanghai with regret theory. Nature Water (2023).
2. Modeling surge dynamics improves coastal flood estimates in a global set of tropical cyclones. Communications Earth & Environment (2024).
3. Recent Advances and New Frontiers in Riverine and Coastal Flood Modeling. Reviews of Geophysics (2023).
4. Measuring compound flood potential from river discharge and storm surge extremes at the global scale. Natural Hazards and Earth System Science (2020).
5. Higher probability of compound flooding from precipitation and storm surge in Europe under anthropogenic climate change. Science Advances (2019).