Justification

Areas at risk from flooding in the Barmouth area (NRW, 2022).

Flood risk management plan

The Western Wales Flood Risk Management Plan has identified that the Barmouth North Promenade is ‘likely to become increasingly difficult to sustain’ due to the implications of cliamte change and associated sea level rise. In the medium to long term (the next 50 to 100 years), consideration to improved sea defences should be given. 

Areas at risk of sea flooding for a 1 in 100 year event at 2019 sea level

The case for change

The main benefit of the project is the reduction of the risk of tidal and surface water flooding to people and property in Barmouth. The proposed scheme(s) will reduce this risk for 757 properties from a 1 in 100 year tidal flooding event up until 2050 (after which time, further consideration of the management solutions will be required).

This will help to ensure a healthy, resilient and sustainable community and tourism industry in future.

The 50-year period has been recommended beacuse modelling has shown that beyond 2050, there will be large-scale changes to the local flood regime, meaning defending Barmouth’s north promenade will become increasingly challenging.

Promenade Cafe inundated by flood water in 2014

Economic case

A broad array of options have been considered in the assessments so far. Through this initial assessment, all offshore options have been rejected because of their impact on the environment, high associated costs, and because land-based options would be needed on top to mitigate against non-wave (tidal) flooding. The Ouline Business Case has found that the preferred option costs less than the value of the damage to property it is defending within its design lifetime.

Weakening and inadequate defences

The existing defences are in a poor condition. Should beach drawdown continue, then structural failure is increasingly a concern. Part of the promenade failed due to unsafe voiding beneath the promenade slab, requiring emergency stabilising repairs in 2020 and 2021. The repair works were emergency measures to extend the life of the existing structures until the preferred option is implemented. Beach levels decrease and defences
deteriorate in condition towards the north of the study area. Studies conclude that overall foreshore bed levels along North Promenade are lowering and this lowering is expected to continue.

The coastal frontage of Marine Parade is comprised of a mixture of defences which are beginning to show their age, and modelling has revealed they would only protect parts of the North Promenade area from a 1 in 5 year flood event (20% chance of such a flood happening in one year). If you want to know more about flood events, click below…

Barmouth flood alleviation scheme

FCRMU@gwynedd.llyw.cymru

YGC | Ymgynghoriaeth Gwynedd Consultancy

 

Swyddfa Penrallt

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