Flooding Risks

Flooding Risks

The flooding across England in the summer of 2007 and Cumbria and Aberdeenshire in November 2009 highlighted the various forms of flooding that we face in the future. It also highlighted the significant and widespread impact on people, businesses, infrastructure and essential services that flooding can cause. The rising temperatures and sea levels associated with climate change are likely to increase the frequency and severity of extreme weather and the flood risks across Essex.

The three main types (or sources) of flooding are from the sea (coastal or tidal), rivers and streams, and from surface water (caused by excess rainfall before it enters the drainage system). All three forms of flooding could occur during a single storm. A different scenario, such as a significant reservoir dam collapse or failure, could bring about rapid flooding. The term 'inland flooding' describes all forms of flooding other than coastal.

Coastal Flooding

Coastal flooding can potentially have the most widespread impact in a single event.

The last significant event of this type to affect the UK was in January 1953, when the east coast of England suffered one of the biggest environmental disasters ever to occur. Flood defences were breached by high tides, storm surges and large waves. Coastal towns in Lincolnshire, Norfolk, Suffolk, Essex and Kent were devastated as seawater rushed into the streets. Over 600km2 of land was flooded, 307 people were killed, and 200 industrial facilities were damaged by floodwater. Over 32,000 people were safely evacuated. A month after the flooding, the estimated cost was £40 –50 million, the equivalent of around £1 billion today, not including the cost of relocation and interruption of business activity.

Since 1953, much work has been done to improve flood defences. Consequently, the likelihood of defences failing or being over-topped by sea tides is substantially lower. In particular, the Thames Barrier's construction in London and associated flood defence systems along the east coast of England mean an adequate level of protection against the sea and tidal surges. In Wales, large-scale coastal defence schemes are being processed at many locations, including Borth in Ceredigion, Colwyn Bay in Conwy, West Rhyl and Denbigh in Denbighshire Riverside in Newport. These schemes are being taken forward with the support of the European Regional Development Fund. They are part of a programme aiming to reduce the risk for over 3,000 properties across Wales. However, the improvements in flood defences have led to significant development of homes, businesses and infrastructure. The consequences of any breach or overtopping flood defences will now be much more critical than previously experienced.

Inland Flooding

The frequency of inland flooding is increasing, evidenced by several rivers and surface water floods over the last few years. Of these, the events of summer 2007 were the most widespread. In June–July 2007, severe rainfall during an extremely wet summer led to the flooding of 48,000 households and 7,300 businesses across England. Other effects of recent flooding have included the closure of primary transport routes, the loss of critical services such as electricity, telecommunications and water supplies, and large numbers of people requiring evacuation and alternative accommodation. Businesses and homes have been made inaccessible for many months while buildings dry out and the damage is repaired. The flooding in Cumbria in November 2009 caused six bridges to collapse, severing the road network and cutting off communities.

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