Coastal flood

A coastal flood occurs when normally dry, low-lying land is flooded by high sea levels. Flooding on low‐lying, densely populated, and developed coasts can be devastating with long lasting, social, economic, and environmental consequences. These include: loss of life (sometimes thousands), both directly and indirectly (i.e. waterborne diseases); billions of pounds worth of damage to coastal infrastructure; and drastic changes to coastal landforms. Globally, several significant events have occurred in the past decade, including: Hurricane Katrina in New Orleans in 2005; Cyclone Xynthia on the French Atlantic coast in 2010; Hurricane Sandy in New Jersey in 2012; and Typhoon Haiyan in the Philippines in 2013. These events dramatically emphasized the high vulnerability of many coasts around the world to extreme water level events.

The UK has a long history of severe coastal flooding. In January 1607, it is estimated that up to 2,000 people drowned on low-lying coastlines around the Bristol Channel; the greatest loss of life from any sudden-onset natural catastrophe in the UK during the last 500 years. During the ‘Great Storm’ of 1703, the lowermost street of houses in Brighton was “washed away”. On 10 January 1928, a storm surge (combined with high river flows) brought about the most recent flooding in central London, drowning 14 people. More recently, the disasters of coastal flooding were brought to the forefront by the ‘Big Flood’ of 31 January–1 February 1953, during which 307 people were killed in southeast England and 24,000 people fled their homes, while almost 2,000 lives were lost in the Netherlands and Belgium.

These events led to wide-spread agreement on the necessity of a coordinated response to understand the risk of flooding, and to provide protection against such events. The 1953 event was the driving force for the Thames Storm Surge Barrier in London and led to the establishment of the UK Coastal Monitoring and Forecasting Service. Without the Thames Barrier and associated defences, together with the forecast and warning system, London’s continued existence as a major world city would be precarious.