Chiswell case study:The View Today
Chiswell looking towards Portland
The view north-west. The village lies at a level that is considerably lower than the crest of the beach
The Chiswell scheme is regarded by many as a highly innovative defence works that has brought stability and confidence to a community that suffered greatly from the severe storms of the late 1970's. It is also, as far as is practicable, sympathetic to the scientific significance of Chesil Beach, the processes acting upon it and it's aesthetic beauty.
The scheme was completed in 1986 and has been tested several times under the one in five year event, the storm surge. However, the scheme cannot fully protect against the one in fifty year event, the ocean swell wave. Furthermore, in addition to the protection of the community and infrastructure, there are a number of other objectives associated with the area, most notably that of regeneration within Chiswell which is the gateway to the Isle of Portland.
As a result, there are conflicts of interest between the various Agencies with an interest and the people who live in Chiswell and here are their views:
Weymouth and Portland Borough Council:
Martyn Gallivan, Principal Engineer, Weymouth & Portland Borough Council 2002
The floods of 1978 and 1979 caused widespread devastation in Chiswell and left the area with an air of neglect and dereliction. The Borough Council, in conjunction with the Chiswell Residents Action Group, set up a General Improvement Area scheme, which also included Fortuneswell, to try to kick start an improvement in the local environment. However, the biggest initiative undertaken was the sea defence scheme.
From the outset it was recognised that it would be impossible to prevent every flooding event. The scheme does have quantum limitations but, so far, has been successful in reducing the number of incidents and their impact on the community. It has been the catalyst for the regeneration of the area, but this in turn has caused tensions with other organisations.
However, a combination of careful risk assessments of individual sites, thoughtful construction details and the injection of public money has allowed new and redevelopments to take place, giving the area a major uplift.
Chiswell has always
had a unique and energetic community, which holds true today. The improvements
that have been effected over the last 20 years, which the sea defence
scheme has given confidence to, have ensured that the local population
have both confidence and pride in their environment.
The original Engineers for the scheme - Brian Hook and John Kemble
Since the publication of the paper in 1991, the Authorities sponsoring the scheme have continued to encourage the regeneration of Chiswell in accordance with the objectives of the General Improvement Area policy. A number of individual properties have been improved and further environmental improvements have been introduced. These have reinforced the well being of the area.
All parts of the Scheme have worked well in preventing flooding in Chiswell and on Portland Road. The interceptor drain and the open channel have been activated on a number of occasions and the gabions have maintained the integrity of the beach.
A further length of gabions has been installed to north of the section installed as part of the scheme, and the beach crest is now protected along the whole length of the existing development. This extension also covers, but only just, the section of beach, which suffered most from the wave, attack in the December 1978 storm when there was a danger of a breach which could have severed Portland from the mainland.
The condition of the various elements of the Scheme are remarkably good and it is pleasing to see how well the gabions are standing up to the exposed conditions in which they are situated. The continuing programme of monitoring and maintenance will always be required if the height of the beach crest is to be protected.
The local Planning Authority has received applications for the extension of residential development both in Chiswell itself and also on the site of the former Naval. Base adjacent to Weymouth road. These will need to be carefully considered in the light of the limitations of the Sea defence scheme. While there are possible ways of dealing with flood water within the new development, these must be regarded as secondary to the need for the gabion protection to be extended northwards to the Portland Harbour outfall
Irrespective of any proposals for the development of the former Base, the completion of this gabion protection from the sea wall at Chiswell to the Portland Harbour outfall of the open channel, as originally recommended by the Consulting Engineers, is an outstanding necessity to providing crest protection against a breach or overtopping which could block the open channel with shingle and cause major flooding.
We should point out that although the Scheme brings substantial relief to the flooding anticipated from swell- wave storms (of a one in 50 year return period) the works are specifically designed to cope with storm surge flooding having a one in 5 year return period. As demonstrated in 1979 the southern length of Chiswell Beach is exposed, through a narrow window of 200 + 240 degrees between the land masses of England and France, to the full unabated energy of ocean swell waves generated by storms hundreds of miles away in the Atlantic Ocean.
Some thirteen years
on from the completion, we have no reason to change our views that the
scheme has greatly reduced the flooding risks to Chiswell and together
with the supporting environmental works the well being of the settlement
has been greatly enhanced. At the same time, the impact on the Beach
and its environs has been minimal.
The local community
Views being explored
The Environment Agency
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