WINTER GROUND SWELLS & STORM SURGES / FREAK WAVES-BEWARE
Caught out by a storm surge-
On a winters day a friend of mine decided to take her young children to Caswell, Gower, Swansea for some fresh air and a run on the beach. It was a bit of a blustery day, the sea was quite rough – nothing unusual for a winters day. There were other people on the beach, in the café and some putting cozies on to brave a winters dip!
She was stood at the bottom of the concrete steps, on the sand with her 1yr old stood next to her, while her 4yr old was clambering around about 5m away on the concrete ramp. The shore line was about 20m away.
She was facing out to sea (luckily) when she realised a wave that had broken was travelling up the beach extremely quickly towards her. Within seconds the water was up to her feet, so she grabbed her 1yr old. The sea water travelled up the ramp towards the 4yr old. My friend was knee deep in sea water as she dived to grab her 4yr old. The force of the water knocked her off her feet, she and her 4yr old went completely under. She just managed to hold the 1yr old above the surface. She held onto them for dear life. The wave retreated back out to sea, leaving her and her eldest soaked, freezing and terrified.
Fortunately, the ladies who were about to go for a swim came over to help. (if this was you, then she was extremely grateful!! So, thank you!) They helped them into the café to warm up (Surfside café staff were also a great help) Once home, the shock of what happened truly kicked in and the ‘what if’s’ played on her mind for days.
This is one of many stories I’ve been told of people getting caught of by storm surges at Caswell and only recently I witnessed a young child get completely wiped out by a freak wave myself.
SO, WHAT CAUSES THAT ONE FREAK WAVE TO SURGE UP THE BEACH??
Having checked the swell and tides conditions for that day, I began to understand why it occurred. The wave period (time between waves) was particularly big that day. It was a big ground swell, created by a storm far out at sea- great for surfing, as it produces powerful waves that come in ‘sets’ (groups of waves). So the sets (approx 3 to 10 waves per set) hit the beach, break on the shore and are followed by a lull (a calm period- do not be fooled-it’s building!!) before the next set come in.
It was also high tide at the time it happened. Caswell is shaped a bit like a funnel higher up the beach by the steps, so when a large volume of water is forced up the funnel neck, It has to find a way to get back out to sea. (check out the blog on rips)
There’s tonnes of information online about freak or rogue waves, taking out big ships, but it often talks about them as huge monster waves far out at sea that just appear from nowhere. However, I did manage to find some information about the types of freak waves that happen on UK beaches and sadly there have been a few fatal incidents. Incidents, that were in fact very similar to what happened at Caswell.
One article I found seemed to make a lot of sense. It suggests that a few factors have to come in to play for a freak wave to occur by land:
– Ground swells that produce powerful sets of waves
– Beach shape- ( funnel shape, combined with high tide at Caswell)
– On shore winds would also have force the water up the beach even more.
So, a set of waves arrives and the first 2 maybe 3 waves break, they all break around the same spot on the beach and they all surge up to about the same distance. That body of water is then trying to find its way back out to sea (see our blog on rip currents). However, in this narrow funnel shaped beach at high tide, with more powerful waves surging forwards, it’s not as easy for the water to find a way back out, so it sort of stays and creates a wall of energy that blocks the next few waves coming through and breaking. But these waves need to break at some point and there are more to come. The wall forces the waves to group together, and yes, you guessed it- it creates one extra large ‘freak’ wave!! It’ll be far bigger than the rest, more powerful and will travel much further up the beach taking out unsuspecting beach goers!
I hope this bit of information helps to keep you more aware when at the beach during big winter swells. Check out the next blog on – ‘How to stay safe at the beach’ for some extra tips and advice.