#LCRI Marine

[walesmarine]

A Severn Barrage: good news for bad surfers, bad news for good surfers

We at Wales Marine have fallen prey to the temptation to use a tabloid headline to describe serious scientific research. The news is, of course, more nuanced than the headline suggests.

The boffins @LCRIMarine have published an article (paywall but see below) with the title "The effects of a Severn Barrage on wave conditions in the Bristol Channel", and they calculate that changes due to a large barrage would be - on average - no more than 5% of the 'natural' case. It's important to note that whilst waves on incoming tides would be slightly smaller, waves on outgoing tides would be slightly bigger, so in principle it would extend the daily surf 'season' (although it would also diminish the number of very large days which would presumably annoy the better surfers out there).

In other words, a barrage is bad news for the good surfers, and good news for the bad ones.

Sorry Swansea

That's not *quite* all there is to it. It turns out that there are winners and losers at particular sites.

The modeling demonstrates that these guys benefit from increased wave height:

North Somerset (+20%)

South Gower Coast

Vale of Glamorgan

The losers include:

Swansea to Porthcawl coastline (biggest decrease)

Llangennith (marginal decrease)

Scarweather Sands (marginal decrease)

Maybe it means that the Welsh coastline will be have to be divided into zones for beginners and advanced. 

Get the detail

There's too much detail in the document for us to do justice here, and before you get too concerned, I suggest that you read the document yourself. You can obtain a copy of the research by getting in touch with the researchers. 

What about flooding?

Natural Resources Wales and residents will be pleased to hear that a barrage and localised increases in wave height don't automatically mean a greater risk of flooding. That's because the increases in wave height are *not* coincident with high water. Good news for barrage advocates!