Frequently asked questions

Why was Hirael at risk from flooding in the past? 

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 center 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.

Is Hirael at risk from flooding? 

Yes unfortunately. Extensive engineering works to alleviate the flood risk from the Afon Adda were completed in 2008, however, flood risk from the coast remains a risk to the area. With current sea level rise predictions due to climate change, the main risk to Hirael now comes from tidal flooding.

 What else are we doing         for the community? 

In line with the various overlapping aims and objectives of the organisations and people involved in the project, the work will investigate both recreational and environmental enhancement of the shoreline area.

Will there be much disruption? 

As with all large construction projects, there is bound to be some disruption through traffic management, noise pollution, impacted view and lack of access to certain areas. However, all of these are temporary, and will be minimised to the best of our ability. It is difficult to say at this stage what the disruption is likely to be like as a final decision has not been reached yet.

How can I have my say as a local resident? 

The council and YGC are keen to hear from the residents of Hirael so we can understand what you’d like to see out of this project, or if you have any complaints or queries about our work. Visit our contact page to get in touch.

I’m interested in the specifics of the project… Where can I find this information? Hirael at risk from flooding? 

The technical information supporting this project can be found on the ‘Technical Documents’ page on this site. If you can’t find what you’re looking for, then please get in touch, or file a freedom of information request with Gwynedd Council.

What does a 1 in 100-year event mean?

The commonly used phrases of “1 in 100-year, 1 in 50-year flood” and so forth refers to the estimated probability of a storm event happening in any given year.
A 1 in 100-year flood has a 1% chance (or 1-in-a-100 chance) of occurring in any given year.

The term “1 in 100-year flood” allows us to place a particular weather event in context with other similar events.
It is wrong to think that a 100-year storm happens only once every 100 years.

While not likely, two 100-year storms can occur within a week of each other. In other words, over the course of 1 million years, these events would be expected to occur 10,000 times.

But, just because it rained 200 milimetres in one day last year doesn’t mean it can’t rain 200 milimetres in one day again this year. 

Hirael flood prevention scheme

YGC | Ymgynghoriaeth Gwynedd Consultancy


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