Bores on the river (From Gazette Series)

Bores on the river

THE Environment Agency has launched a new 2006 timetable for the spectacular natural bores on the River Severn.

The times of these stunning spectacles, which have attracted visitors and enthusiasts for generations, have been published in new leaflets made available to the public this week.

The Severn Bore is a tidal wave that occurs in the lower reaches of the River Severn and is one of the nation's most interesting and unusual natural phenomena.

It is a natural process which happens in the lower reaches of a few rivers throughout the world, during high tides. The name bore, as applied to the tidal phenomenon, appears to be derived from the Scandinavian or Icelandic "bara" meaning a wave, swell or billow.

A bore is formed when the tide rises in a converging channel with a rising riverbed, forming a funnel shape. Large tides occur when the moon and sun are in line with the earth at their closest respective distances above the equator. The largest spring tides occur near the autumn and spring equinox, usually in March and October.

Although there are no five star bores on the River Severn, the best four star bores, which are almost as impressive, can be seen in March, September and October and sometimes take place several times a month.

The Severn Estuary receives the second highest tide anywhere in the world and the differences between the lowest and highest tide in one day can be more than 14.5 metres. These high or spring tides occur on several days in each lunar cycle throughout the spring and autumn.

The timetable in the leaflet only details tides that may result in major bore. Times are approximate and can vary by as much as 30 minutes each way due to differing weather conditions.

The leaflet also contains a map and advice on the best viewing locations as well as important safety information as spectators and river users need to be aware of the risks associated with this phenomenon. Occasionally, the rising waters have cut off spectators and their vehicles, leaving them in need of police rescue.

"When the bore comes, the stream does not swell by degrees, as at other times, but rolls in with a head foaming and roaring, as though it were enraged by the opposition which it encounter" wrote Thomas Harrel in 1824.

A copy of the leaflet can be obtained free of charge from the Environment Agency by telephoning 08708 506506. It can also be viewed on the Environment Agency website by visiting www.environment-agency.gov.uk