An investigation into flooding on West Kirby promenade during Storm Pierrick last April has concluded it was an “extreme event” which was more than the new defence wall was designed to cope with.
However it says that the structure prevented more damage than would have been the case had it not been in place.
Wirral Council faced criticism when gale force winds forced waves over the top of the £20 million wall on 9 April leading to three residential properties and a business becoming flooded, and cars floating down the road.
In the aftermath, chair of the planning committee, Cllr Stuart Kelly, demanded an investigation into why it had, in his words, “failed so spectacularly”.
Now, Wirral Council has published what is known as a Section 19 report, which looks at the circumstances surrounding what happened, and also makes recommendations for the future.
Flooding on South Parade last April
It notes that, on the day, a flood warning specific to West Kirby was not issued by the Environment Agency as the criteria “was not met in their forecasting model.”
The report states: “At West Kirby gale force winds blowing from a west north-westerly direction, combined with high tides and a high storm surge, drove waves at speed across the promenade on South Parade.
“The new flood alleviation wall intercepted the waves, reflecting them upwards where they were influenced by the Force 9 west north west winds with the result that significant quantities of water were blown onto the landward side of the wall, which then became trapped by both the wall and tide-locked highway drainage.
“Once tide levels had dropped sufficiently, this water could drain away, however debris carried in flood waters appears to have impeded the functionality of the highway drains.”
The investigation also found that South Parade was not immediately closed to traffic, which contributed to the flooding of properties as vehicles drove down the road and formed “bow waves”.
It concluded that “public expectations that the wall would prevent all flooding may have been a factor in not utilising property level protection” and that three residential properties which experienced internal flooding would benefit from protection to mitigate the risk posed by future storms that breach the wall.
Other recommendations include:
- Installing non-return valves within the demountable flood barriers to assist drainage
- Measures to manage residual flood risk to the highway
- Reviewing the triggers for issuing a flood warning for West Kirby
- Reviewing the procedure for for closing South Parade
- Installing secondary defences at the entrance to Coronation Gardens during extreme events
The report can be read here: https://democracy.wirral.gov.uk/documents/s50124417/S19%20Investigation%20Report%20West%20Kirby%20Flood%20Event%2009-04-2024.pdf
