Coastal flooding

Causes of coastal flooding

Coastal flooding is a sudden and abrupt inundation of a coastal environment caused by a short-term increase in water level due to a storm surge and extreme tides. The magnitude and extension depend on the coastal topography, storm surge conditions and broader bathymetry of the coastal area.

Coastal flooding is generally a natural process and constitutes an important part of the natural coastal dynamics, especially for salt marshes and mangrove forests. In areas with human activities, however, it can constitute a major challenge and lead to loss of property and lives. Over the last 200 years, it is estimated that about two million people have been killed in flood events mainly in South Asia and with growing coastal populations and sea level rise, the world faces increasing potential for coastal flood disasters.

Flood management & Disaster Risk Reduction

Flooding constitute a particular challenge in low-lying areas as deltas and coastal plains and land subsidence caused by sediment deficits/compaction or ground water extraction can further exacerbate the problem. Technical measures for flood control include dike construction, maintenance of natural dune systems, protection of coastal ecosystems, flood proofing and accommodation activities and early warning systems. Generally, even moderate flooding hazards should be taken very seriously due to the potential disastrous consequences, and flood protection is a key aspect in coastal Disaster Risk Reduction. The Coastal Hazard Wheel aims to improve the management of these challenges in a holistic fashion.

The Quick start guide can be used together with the Catalogue of Management Options to decide on appropriate flood management strategies for a specific coastal area. The automated Coastal Hazard Wheel App provides detailed coastal classification, hazard mapping and management guidance for the worlds coastlines and will be further developed with future data system upgrades. For further technical information or assistance with specific flood management activities, please get in touch with us. Additional resources on design of coastal protection measures can be found under Engineering guidance