Flooding
From HalesworthTownPlan
Contents |
Agency
The Environment Agency
Publications
- Halesworth Flood Defences Pre-Feasibility Report – Halcrow on behalf of the Environment Agency, May 2004.
- Halesworth Flood Alleviation Scheme – Preferred Option Consultation – Environment Agency, September 2005
- East Suffolk Catchment Management Plan Summary of Draft Plan – Environment Agency, June 2008
Present situation
Halesworth is situated on a tributary of the River Blyth known locally as the Town River. It is formed from the Chediston and Wissett watercourses which converge just to the west of the Town. It then runs through the centre of the Town, under the Thoroughfare and Saxon Way, through the Town Park and Millennium Green joining the River Blyth approximately 0.5 km. east of the Town. The New Reach was constructed in the mid 18th Century as part of the Blyth Navigation and forms an overflow channel at times of heavy flow from the Town Park to just downstream of the railway bridges. Normal tidal influence only reaches the sluice at Blyford Bridge 3km.downstream and has no impact on Halesworth.
There is a long history of flooding problems in the Town with major floods in the last century occurring in 1912; 1939; 1968 and 1993. Initial flooding takes place in the fields upstream and downstream of the Town, followed by the Town Park and the gardens of properties in Chediston Street. The Thoroughfare Bridge then acts as a barrier with levels building up behind it and overtopping the southern bank and flowing into the Thoroughfare. In 1993 the water was 450mm [18”] deep in the Thoroughfare and flooding affected 45 properties. The Environment Agency 1999 Flood Risk Area Maps indicate that over 100 properties are at risk on the south bank of the river through the Town Centre along the Thoroughfare and Chediston Street but also including areas on the north bank off School Lane, Bridge Street and Quay Street.
Following the flood in 1968 work was undertaken to widen the channel through the Town, low earth bunds erected around the Old Rectory and channel improvements to increase the flow through the Town Bridge.
Since the flooding in 1993 numerous studies have been undertaken by the Environment Agency to investigate a number of options that would meet the economic criteria for attracting Government funding. The 2004 Report from Halcrow recommended a flood channel in the Town Park with flood berms downstream of the Thoroughfare Bridge but by September 2005 this option was considered hydraulically, environmentally and visually unacceptable. The upstream flood storage on the Chediston and Wissett watercourses were not considered to hold sufficient water to significantly reduce the flood risk and were very expensive. However it quotes a 1995 study that states that the only option likely to improve the standard of protection to all properties in the Town was the provision of upstream flood storage. However none of the options considered at that time were deemed to be economically justifiable.
In September 2005 consultation was carried out on a scheme to protect the Thoroughfare by steel piled walls and wall raising upstream of the Thoroughfare Bridge and behind the properties on the west side of the Thoroughfare. This left Chediston Street and the other properties with no increased protection and possibly in a worse position with the water that had escaped into the Thoroughfare now constrained by the new defences.
In June 2008 the Environment Agency produced a draft East Suffolk Catchment Flood Management Plan [CFMP] “Managing Flood Risk”. This estimates the economic property damage for Halesworth as:
- £693,000 for a 1:10 year flood event
- £953,000 for a 1:100 year flood event
- £1,261,000 for a 1:1000 year flood event
They also expected the flood risk to increase with climate change. However with no threat to life and no key services at risk their favoured Policy Option was to Reduce existing flood management actions (accepting that flood risk will increase over time from the baseline)
In their response to this consultation the Town Council said they considered this conclusion totally unacceptable. The finalised CFMP has not been published.
Associated Issues.
- Retail – Recent changes to the legislation on building in the flood plain seem to have blighted the Town Centre site and clarification is required on this issue. The area behind the western side of the Thoroughfare is also in the flood plain and the future of this site needs clarifying.
- Open Space – Town Park management is possibly being taken over by the Town Council. The New Reach is registered as a Village Green and was originally the responsibility of the Halesworth UDC but recent attempts to clarify responsibility have not been successful. Maintenance of the channel has been undertaken by the Environment Agency because it operates as a flood channel. Maintenance of the towpath has been undertaken by the County Council
- Biodiversity – New Reach County Wildlife Site maintenance and responsibility.
- Access – Towpath maintenance and Footpath 10 re-opening.
Draft Target
The present level of protection was calculated in 2000 as 1 in 20 years. Our target is for all properties to have a protection of 1in 50 years.
Action
Set up a small sub-group to review all published information and then explore with the Environment Agency what work would achieve this level of protection and what options there are for financing this work. Establish limitations on the future use for sites in the present flood plain close to the Town Centre.
