Learn more about this naturally occurring tidal wave and find out when and where you can view it.
What is it and why does it happen?
A bore is a naturally occurring tidal wave
which forms as the rising tide forces a large volume of water through a narrowing river channel with a rising river bed. Bores only occur during high tide
in the lower reaches of a few rivers with large tidal ranges throughout the world.
The Severn Estuary
has the second highest tidal range in the world. In any one day the difference between the highest and lowest tide can be more than 14.5 metres.
The Severn Bore has an average speed of 16km per hour
and can reach two metres
in height. The size of the bore can be affected by opposing winds or high fresh-water levels which reduce its height and delay its arrival. A following wind can increase its height and speed when it arrives.
The name bore comes from the Scandinavian or Icelandic ‘bara’ meaning a wave, swell or billow.
When can you see it?
The best time to view the Severn Bore is during the especially high tides around the autumn and spring equinox – usually in March and September.
A predictions timetable for 2012 showing where and when the Severn Bore can be seen is available on the Severn Bore website.
Where can you see it?
The Severn Bore can be seen along the lower lengths of the River Severn downstream of Gloucester. Due to the presence of weirs there is no bore upstream of Gloucester. The most popular viewing points are:
- Over Bridge
- Weir Green
These viewing points are only suitable for small numbers of people and parking is limited. Please respect the locals and park your car sensibly. Keep to public footpaths and roads as the adjoining land and accesses are privately owned.
While not so spectacular, the incoming tide and developing bore can also be seen in the upper Severn Estuary at Epney, Newnham and Fretherne. Bore times are 20, 60 and 85 minutes before Minsterworth respectively.
Health and Safety
When viewing the Severn Bore please be aware of the following:
- There is a risk of flooding after the first bore wave has passed as water levels continue to rise for an hour - the danger is particularly great near Stonebench.
- Take care where you stand to watch the bore and where you park your vehicle - rising waters can cut you off from your car.
- Be aware of changing weather conditions – wear suitable clothing and footwear.
- Don’t walk out onto sandbanks – you may get stuck in quicksand.
- Children should be supervised at all times.
- Severn Bore safety (PDF, 99KB)
Information on boat safety is available from the Gloucester Harbour Trustees who are responsible for navigational safety in Gloucester Harbour.