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This publication is available at https://www.gov.uk/government/publications/somerset-levels-and-moors-reducing-the-risk-of-flooding/somerset-levels-and-moors-reducing-the-risk-of-flooding
The Somerset Levels and Moors lie between the Quantock and Mendip hills in central Somerset.
Much of the area has been historically drained for agricultural and residential purposes. The Levels are cut in 2 by the Polden Hills which run parallel with the Mendip Hills further to the north. The River Parrett drains the southern section and the Rivers Axe and Brue the northern.
The need for improved flood protection
In early 2014 the Somerset Levels and Moors experienced widespread flooding, particularly within the Parrett and Tone river catchments. It is the largest flood event ever known.
The Environment Agency estimated there were 100 million cubic metres of floodwater covering an area of 65 square kilometres. Residents of Northmoor (Moorland, Chadmead and Fordgate) had to leave their homes at the height of the flood and many communities were cut off by floodwater.
Records of flooding go back as far as the 1600s and some of the more significant events over the last 100 years occurred in 2012, 2000, 1997, 1960 and 1929.
Repairs to flood defences maintained by the Environment Agency
As a result of the winter 2013/2014 flooding, there were nearly 50 assets (embankments, pumping stations, sluices, flood gates and coastal flood defences) across Somerset that needed to be repaired before winter 2014/2015.
Some of the these repairs were included in the 20 year flood action plan for the Somerset Levels and Moors developed in March 2014, and also the wider Somerset area.
New and more efficient pumps have been installed by the Environment Agency at some key sites and in some areas permanent defences have been built to replace temporary ones used previously.
The standard of flood protection has been restored at the majority of sites, but the Environment Agency is working through the winter to make defences more resilient.
The Environment Agency has contingency plans in place to ensure no communities are at an increased flood risk compared to before the winter of 2013/2014.
New flood defences
The Environment Agency built a new permanent defence at Aller Drove to replace the temporary defence installed. The work included raising the road and installing a new kerb, to help reduce flood risk to properties most at risk at Aller.
Aller Drove will also benefit from works downstream at Beer Wall, which allows flood water to be conveyed under the road through two new culverts, two new channels and two large water control structures. This work was funded by the Local Enterprise Partnership and delivered by the Environment Agency via the Somerset Rivers Authority.
After working closely with the community at Westonzoyland, the Environment Agency built a new permanent defence to replace the temporary defence. This includes a new sheet piled wall which will help reduce flood risk to properties in Westonzoyland.
River Sowy & King’s Sedgemoor Drain enhancement options 2016
The Environment Agency has completed an initial investigation of different options to enhance the capacity of the River Sowy and King’s Sedgemoor Drain. By increasing the capacity of the river system the aim is to reduce the risk, depth and duration of future flooding. The Environment Agency has carried out this assessment on behalf of the Somerset Levels and Moors 20 year flood action plan partners.
A report has been published reviewing the options for a Parrett Barrier to manage flood risk in Bridgwater and the surrounding areas. This review looked at whether the recent flooding, updated data or other evidence might influence the preferred option or timescale for a proposed barrier.
The 20-year flood action plan identifies the need to review the effectiveness of dredging and identify locations for further dredging across the Levels and Moors.
The 8km dredge of the Tone and Parrett was completed in October 2014, and a project is underway to identify possible additional locations where dredging is, in future, likely to be a cost effective way of reducing flood risk. This will provide the evidence base to support future decisions on whether or not to dredge these sites as part of the 20 year plan.
Other flood risk management options
Dredging can be a solution for reducing flood risk in the right place; it is just 1 option for flood risk management and is not suitable for all sites. There are many alternative ways of reducing flood risk and some may be more effective than dredging, depending on the characteristics of the watercourses. Other solutions could include building new banks, setting back banks, improving pumping capacity or additional maintenance including weed control and the removal of blockages.
Assessing the costs of additional dredging
For locations where modelling demonstrates an overall flood risk benefit, the next step is to consider the criteria that will influence the costs of dredging, such as the working method, silt disposal options, and environmental considerations. A broad assessment of the cost effectiveness of dredging would then be provided, alongside an appraisal of alternative options that could give the same, or better, flood risk benefits.
A summary of all the assessments for each of the 10 locations will be published on this website. There are currently no funds allocated for future dredging, but funding partnerships may be able to secure some money for some of this work in future years.
Effectiveness of further dredging – 10 locations
|Parrett||Thorney to Langport (Huish Bridge)|
|Parrett||Langport (Huish Bridge) to Tone confluence|
|Parrett||North Moor to Bridgwater|
|Tone||Ham to Hook Bridge|
|River Yeo||Huish Episcopi pumping station to Parrett confluence|
|Penzoy River||New Southlake inlet to Kings Sedgemoor Drain|
|River Axe||Clewer to New Cut|
|Cheddar Yeo||Froglands to River Axe confluence|
|Panborough Drain||Whole length|
|Glastonbury Millstream||Whole length|
The River Brue maintenance pilot, which involves dredging a section of the watercourse, is being considered and modelled as a separate piece of work.