Climate change will bring wetter winters, stormier weather, sea level rises and great extremes in weather conditions. After the floods in Cumbria a few years ago, work began in Carlisle to defend the city against similar significant floods.
Such events could be expected to become larger and more frequent as a result of climate change.
In January 2005, over 1,800 Carlisle properties flooded, two residents died as a result and over 70 people sustained injuries. A major incident was declared and large areas of the city were evacuated. It was a tragic event for the city. And the damage incurred cost an estimated £250 million.
What we did
The Environment Agency had already been planning a flood alleviation scheme. The first phase of which was completed in spring 2008. It protects nearly 1,500 properties, using four kilometres of raised flood defences.
Following the floods, we updated proposals for the second phase of the scheme, taking into account new information we had gathered on flood levels and the expected impacts of climate change.
Construction is now underway and due to be completed in 2010. It will protect a further 1,137 properties and includes five kilometres of raised flood defences. The scheme will cost £25 million. The flood defences have been designed where possible so that the height can be increased in future with a minimum of modification.
Both schemes can cope with a significant flood event whose likelihood of occurring will increase with climate change. They both significantly improve the standard of flood defence to a level of service equivalent to a 1 in 200 year storm using today’s hydrology.
This scheme has also been Highly Commended at the Institute of Highways and Transportation awards 2009 in the Urban Design category.
How we did it
Some of the flood alleviation techniques we have used include:
- building floodwalls, clad with locally appropriate materials, along the River Caldew and sections of the River Eden
- building earth flood embankments along the rivers Eden and Petteril
- raising of two footbridges to reduce the risk of debris such as fallen trees blocking the river
- installing a pumping station on the Little Caldew
- removing obstructions from the river
- reopening the natural floodplain downstream of Carlisle
- creating four areas of improved habitat for wildlife.
‘The work at Carlisle is an important response to flood risk that will inevitably increase as a result of climate change, says Alistair McNay, a Landscape Architect from Axis, a Town Planning Consultancy who worked on the project. ‘The project has been designed so that future generations can adapt it to their needs if climate change is not mitigated. It has also enabled the Environment Agency to provide other environmental enhancements such as an improved cycle path network and new biodiversity habitats for wildlife.’
Factoring climate change into the design and location of developments is an important way to reduce the risk of future flooding. After the floods, we revisited many planning applications to make sure that they complied with up-to-date information.
Who was involved
Carlisle City Council
Cumbria County Council
Local Businesses and Landowners
Atkins (design consultants)
Jacobs (design consultants)
Halcrow (design consultants)
Axis (design consultants)
Volker Stevin (principle contractor)