Nature Features

The Severn Bore, taken by Chris Witts

Chris Witts is an expert on all things about the River Severn in Gloucestershire. He writes the following...

The Romans on first seeing the Severn Bore a little below Gloucester ran scared thinking the end of the world was nigh!

Old prose tells of a raging, boisterous mass of water surging up the Severn, overflowing the banks and filling the land far inland with water and overturning the toiling barge out in the river with its helmsman having fought a losing battle to keep his craft heading into the wave to avoid the turbulence.

These days it is the surfers who ride the wave, all aiming to stay on their boards until they reach Gloucester whilst thousands of people line the banks hoping to see one of nature's finest, natural phenomenons.

If the barometric pressure is low, the wind from the southwest and just the right level of water in the river, then a large spring tide will produce a high bore wave.

Photo: Chris Witts

Eerie

There is a spring tide every two weeks (a few days after a full and new moon) and there are about fifty good bores each year during the spring and autumn equinoxes.

Some of these good bores will occur on the night tides, when you must be there in total darkness with no artificial lighting at all.

The purpose of being there for a night time bore is to see the bore only by moonlight and to hear the eerie sound of the bore crashing through the trees on the banks as it races up river.

Wherever you choose to view the bore (anywhere between Minsterworth and Over at Gloucester) arrive early and stay safe.

Photo: Chris Witts

Powerful

Don't be tempted to climb down the bank to get a better photograph as you may get swept off your feet!

As the bore passes don't rush off, wait a little and reflect on what you have witnessed.

The Severn leaves the Atlantic and races up river then meets the current coming downriver from the Severn's source 220 miles away.

The powerful incoming tide pushes against the strong current and reverses the flow so the bore wave is formed, which increases in height as it is squeezed between the narrowing banks of the river.

This is the mighty Severn Bore, the most powerful in Europe!

Photo: Chris Witts

2009

2009 promises to be a better year for the Severn bore than recent years.

One of the highest tides of the year is predicted for Thursday 12th March at 08:45 at Minsterworth.

This should produce a '4 star' bore if there is not too much floodwater in the river, the wind is from the right direction and the barometric pressure is okay. These requirements produce a watchable bore.

During the months of August and September there are a few '4 star' bores forecast but these are on the evening tides.

Many people ask me why the bores have been poor in recent years. It is down to the moon.

The moon controls our tides and the lunar cycle is now entering a better phase in which better bores should be seen.

This article is an external contribution and expresses a personal opinion, not necessarily the views of the BBC.