Coastal flooding
| Impact | 5 |
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| 3 |
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| 2 |
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5 |
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| Likelihood | |||||||||||||||||||||||||||||||||||||||||||||||||||
| ID | 51a |
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| Risk theme | Natural and environmental hazards |
Impact & Likelihood
| 5 | Catastrophic |
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| 4 | Significant |
| 3 | Moderate |
| 2 | Limited |
| 1 | Minor |
| 5 | >25% |
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| 4 | 5-25% |
| 3 | 1-5% |
| 2 | 0.2-1% |
| 1 | <0.2% |
Background
Coastal flooding is caused by high tides, low pressure weather systems, and surge conditions caused by strong winds blowing large waves towards the shore. As sea levels continue to rise as a result of climate change, the risk of coastal flooding will also increase.
Flooding events have serious consequences on coastal communities, including disruption to essential services, the economy and environment, with disproportionate effects on vulnerable groups. The government has well-established arrangements for minimising the risk from flooding including, the deployment of fixed and temporary defences, public warning and informing alert systems, and local and national response mechanisms.
Scenario
The reasonable worst-case scenario is based on coastal flooding across the east coast of England, impacting a very large number of residential properties. Comprehensive warning and informing systems would be employed and a large number of people would require evacuation and shelter, with a significant proportion of these requiring assistance. The number of people affected could be even greater during the holiday season. There would be fatalities and casualties, including those whose death, illness, or injury are an indirect consequence of flooding. Large areas of road and railway could be flooded, with other major infrastructure such as schools, hospitals, care homes, emergency services and agricultural land also affected.
Key assumptions
A key assumption for this scenario is that the existing high levels of preparedness for local planning and response continue to operate. The Environment Agency (EA) and others continue investing in new coastal defences and maintaining existing coastal defences. There would be between 5-7 days of flood forecasts showing medium and then high risk of coastal flooding from the Flood Forecasting Centre (FFC). Severe Flood Warnings would be issued a minimum of 24 hours in advance by the EA.
Variations
Coastal flooding is highly variable and dependent on where the flooding occurs. Certain areas are more vulnerable to flooding, and the impact there would be higher. Higher risk areas also have greater protections via barriers and advanced warning systems.
Response capability requirements
An advanced flood forecasting capability is available via the Met Office and the FFC. The FFC produces products that identify potential flood impacts from weather scenarios. These products help inform long-term emergency planning and in the lead up to a potential flooding event. The FFC target is to consistently provide at least a 3-day lead time for coastal events.
The EA leads operational preparedness and response to flood impacts and, during local-level operation response, would work as part of a multi-agency team, coordinated through the LRF to support flood preparedness, warning and informing the public, operating defences and systems and coordinating any evacuation including accommodation requirements. The local response will have access to operational resources including temporary flood barriers, mobile pumps and the necessary logistical support to transport and deploy these resources. Flood rescue teams (which consist of over 100 specialist flood rescue teams on standby to be deployed across the country), national mutual aid and military assistance can also support a local response. Any national coordination would be led by the EA and the Department of Environment, Food and Rural Affairs.
Recovery
A major recovery operation is required involving economic, environmental, infrastructure and humanitarian impacts. The recovery process would likely last beyond 2 years, especially if significant repairs are required to infrastructure, homes and businesses. Mental and physical impacts on affected citizens may also be longer-term.