23/01/2006 - The Environment Agency’s newly-launched 2006 timetable for the Trent Aegir and the Severn Bore is available from today. These spectacular natural events have attracted visitors and enthusiasts for generations. Although there are no five star bores (known as aegirs on the River Trent), the best four star bores, which are almost as impressive, can be seen in March, September and October.

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. 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 Trent Aegir is a tidal wave that occurs in the lower reaches of the Trent, between Derrythorpe and Gainsborough, and is still considered to be one of the nation's most interesting and unusual natural phenomena, although it is smaller than its Severn counterpart.

The timetable in the leaflet only details tides that may result in major bores or aegirs. 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.

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.

More information:

Severn Bore

"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.

One of the most exciting and interesting events to occur naturally on a river takes place throughout the year on the River Severn. Several times a month, a tidal wave makes its way along the river. It is known as the Severn Bore.

Tide waves (bores) naturally occur on rivers with large tidal ranges. This natural phenomenon occurs 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.

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

The size of the bore can be affected by opposing winds or high freshwater levels which reduce its height and delay its time of arrival, but a following wind can increase its height and speed up its arrival. It travels at an average speed of 16kph and has been known to reach an incredible 2 metres in height.

The bore can be seen along the lower lengths of the river to Gloucester. The incoming tide and bore can be seen, although not quite so impressively, in the upper estuary, at Epney, Newnham and Fretherne where times are 20, 60 and 85 minutes before Minsterworth respectively.

‘The big muddy’. One interesting feature which can be overlooked is after the bore wave has passed, the river level rises, presenting a slightly different aspect to the river scene, plus the river is flowing in the wrong direction. This continues for up to an hour after the wave has passed until the river magically appears to stand still before resuming its normal direction of flow.

Recommended viewing positions

Over Bridge – the Severn Bore can also be viewed from the older bridge but children should be supervised at all times, as it is recognised by English Heritage as an historical site. Off-road parking is available two hundred yards from the new bridge, but it is quite limited. Disabled access – there is a suitable pavement to view it from. Children should be supervised at all times.

Minsterworth – There are many viewpoints around Minsterworth, of which the Severn Bore Inn is the biggest attraction. This offers a viewpoint adjacent to the inn and also offers an alternative view for customers from its beer garden. There is another viewpoint by Minsterworth Church, where a public footpath runs alongside the riverbank. Spectators are reminded that viewpoints, adjoining land and accesses are privately owned and to keep strictly to the public footpath along the riverbank. Limited car parking is available at the Severn Bore Inn. Be aware that the police may prosecute if any car is improperly parked at Minsterworth.

Stonebench – The danger associated with rising water is particularly great at Stonebench. This viewpoint is excellently sign-posted from Gloucester. It is situated on the opposite side of the river facing Minsterworth. Road access is a single lane with passing places only and parking is not available. Poor weather conditions can cause the viewpoint to be very slippy and so sensible clothing and footwear is needed. Children must be supervised at all times.

Weir Green – Situated between Elmore Back and Stonebench, this viewing point forms part of the Severn Way footpath. Limited car parking is available. Please be respectful of local property and animals. Be wary of changing weather conditions and remember to wear suitable clothing and footwear. Children should be supervised at all times

The Trent Aegir

Tide waves (bores) like the Trent Aegir naturally occur on rivers with large tidal ranges. This natural phenomenon occurs 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 wave, swell or billow.

A bore is formed when the tide rises in a converging channel with a rising riverbed formed in a funnel shape.

The Trent Aegir is named after the god of the seashore or ocean in Norse mythology and, like the Scandinavian sailors in the myths, river people would fear the aegir as it is very unpredictable and would sometimes surface to destroy ships. Sometimes the tide merely changes the flow of the river but, at its best, the wave breaks with fury as it passes by and causes damage to boats on the moorings or in its wake.

In the days of small craft it was custom to shout ‘Ware Eagre’ to warn of its approach. In 1013, the Viking King of Denmark, Svein Forkbeard, together with his son Canute, arrived with an army to conquer The Danelaw and ultimately England. He moored his ships in the haven at Morton Bight, near Gainsborough, and marched his force to the nearby encampment on Thonock Hill. A year later, upon Svein’s death, Canute became king and it has been suggested that it was the Trent Aegir that was responsible for Canute getting his feet wet by trying to turn back the tide, not the sea.

The most reliable time to see the Aegir is after a long period of dry weather. It usually appears during high spring tides, but the scouring action of winter floods and above average water levels in the river can reduce its size considerably. You can view the Aegir from around Derrythorpe where the river narrows and there is a slight incline in the bed up to Gainsborough. Upstream of Gainsborough, the Aegir peters out.

Recommended viewing positions

Gainsborough, where viewing is from the flood defences. There is off road parking and it is the most suitable location for wheelchair users.

The aegir is also clearly visible at Morton and at West and East Stockwith, but there is only roadside parking in these villages.

Owston Ferry and East Ferry are recommended, and also at Susworth, but again there is only roadside parking, and viewing is from the top of the floodbank and therefore not suitable for disabled people.