PLANS have been submitted to build 600 metres of new sea defences to help protect a north Wales city from future rising sea levels.
With the existing protection at Hirael described as “limited” – with the only formal defences in the area being a sea wall “in various states of disrepair,” – the area is said to be in need of a long term solution.
Bangor has been identified as an area at risk of flooding due to climate change, with the low-lying area facing a combination of risk factors including a rise in sea levels, ground water caused by a high-water table, rainwater, surface water and water from Afon Adda that discharges into the sea.
The area around Beach Road suffered severe flooding in both 1923 and 1973, but with climate change predicted to cause a rise of up to 1.2 meters in the level of the sea by the end of the century, the local Senedd Member has already warned that without further flood defence work the consequences for Hirael residents and businesses could be “severe.”
With a rise of between 12-13cm having already been noted between 1991 and 2015, the Gwynedd Council plans span four sections, namely:
Beach Road East carpark: A new concrete wall between the existing field and cycle path. Cycle path to be graded and aligned with reconstruction of slipway to provide access to the foreshore with a flood gate installed.
Sea wall at promenade frontage: A retaining wall to replace existing gabions at the promenade, from Beach Road East carpark to Welsh Water pumping station.
Embankment behind Welsh Water pumping station: A compacted 1m wide crest topsoil and clay embankment with a re-routed cycle path installed directly behind the embankment.
Glandŵr Road: An approximately 20m section of road at Glandwr Road raised slightly (highest point of increase is 0.5m). Construction of a new reinforced concrete wall.
To provide adequate flood protection, its proposed that the wall would be raised some 1.3 m (4’3”) above the existing level of the promenade.
Historic flooding in Hirael has been caused by high rainfall coinciding with a high tide. The Afon Adda, which flows underground for 4 km through the centre of Bangor was diverted through culverts which were too small, and therefore when high tide occurred at the same time as peak river flow, the culvert was overwhelmed.
But while extensive engineering works to alleviate the flood risk from the Afon Adda were completed in 2008, flood risk from the coast remains an issue in the area.
Designed by Ymgynghoriaeth Gwynedd Consultancy, the supporting documents note, “The existing coastal defences at Hirael are limited with the only formal defences in the area being a sea wall which in various states of disrepair, a revetment and gabion baskets at the coastal frontage, north east of Beach Road.
“Currently, there are no other structures that manage wave overtopping and inundation. Temporary flood barriers such as sandbags have been deployed in the past along the length of the sea wall and two slipways to deal with high tides and wave surges but are not a sufficient source of long-term flood protection.”
Its expected that Gwynedd Council’s planning department will consider the application over the coming months.
For more information about the scheme visit: https://hirael.ygc.cymru/