Estuary

The Severn Estuary is a huge diverse area with fascinating natural, cultural and geographical features. These pages are designed to give you a flavour of the estuary and act as a resource for further study with links and contacts to other groups involved with the Estuary.

The geographical area of the Severn Estuary Partnership

Although the Severn Estuary is commonly seen as the water body from the Second Severn Crossing to a line between Lavernock Point near Cardiff and Brean Down near Weston-super-Mare, the area covered by this report includes the Inner Bristol Channel and the upper Estuary as far north as Gloucester (See Fig. 1). This extends to the tidal limits of the river and incorporates the area covered by the Severn Estuary Partnership where there are close links between the Estuary and on and offshore activities and uses. For selected topics the report includes discussion of areas to the west of the area highlighted, as this region has a significant effect on the Estuary’s economy and environment.

Your Estuary

Many people benefit from the Severn Estuary. The Estuary provides resources for communities around its shores through recreation, transport, trade and materials. It supports many activities ranging from sailing and fishing to dredging and offers opportunities for renewable energy generation. However, the Estuary is a fragile habitat and therefore needs to be sustainably managed and looked after for future generations.

The natural environment

The Severn Estuary is a huge, diverse area with many fascinating natural, cultural and geographical features.

The Estuary is fed by the catchments of five major rivers; including the River Severn, the longest river in Great Britain. Not only is it Britain’s second largest estuary, but it also boasts the highest tidal range in Europe with a tidal regime which causes strong tidal streams, mobile sediments and the famous Severn Bore (See Fig. 4). It contains a variety of landscapes and seascapes including salt marshes, cliffs, islands and tidal flats. It is a well known and important nature conservation site because of its internationally important habitats and species, including over-wintering birds and migratory fish.

The human environment

Along with over a million people who live close to the Estuary’s shores in large low-lying urban areas, its waterfronts, coastal resorts and other recreation resources attract several million visitors a year. Significant industrial developments, ports and port-related activities are all supported by excellent land and sea communications, including links to Britain’s major motorway network. Estuary industries include port-related installations, chemical processing plants, power stations and offshore aggregate extraction. Deep-water channels, cooling water and relatively cheap waste disposal are the Estuary’s natural ‘resources’ for such activities.

The past. . .

For centuries the region has been a focus for human activities, a location for settlement, a source of food, water and raw materials as well as being a gateway for trading and exploration. As a result the Estuary also holds a wealth of maritime archaeological and paleontological sites, as can be seen in Fig 5 (B), which shows the Mesolithic footprint of a child at Goldcliff.

The future. . .

Potentially competing and conflicting uses present challenges, particularly in the context of climate change. There are concerns associated with the maintenance of the Estuary’s natural environment with regards to sea level rise alongside increasing demands for urban and industrial expansion. The large tidal range periodically results in frequent debate over the potential for offshore tidal energy generation. However, the Welsh and UK Governments have stated that it is not timely to develop any Severn tidal power scheme because of its associated costs and risks at present.

Key features of the severn estuary

  • Total area = 55,684 ha1
    • Intertidal area = 9,971 ha2
    • Subtidal area = 6,275 ha2
    • Non tidal area = 623 ha2
    • Length of coastline = 353 km1
    • Length of channel = 111.2km1
    • Tidal Range at Barry = 10m3,4
    • Tidal Range at Avonmouth = 14m3,4
  • Main sources of freshwater input = Rivers Wye, Usk, Severn, Avon.
  • Key habitats = Saltmarsh, Intertidal mudflats, Rocky intertidal habitats, Subtidal sandbanks (Seagrass beds & Biogenic reefs)
  • Designations = Special Protection Area, Ramsar, Special Area of Conservation, Site of Special Scientific Interest
  • Adjacent cities = Bristol, Cardiff, Gloucester, Newport.
  • Human population = ~1,039,0001
  • Major activities = Ports & shipping, energy generation, aggregate extraction, sailing and angling

 

Much of the information covered in this section comes from the ‘State of the Severn Estuary Report’, a non-technical and easy to understand document that aims to inform a wide ranging audience, including Estuary users and local people about why the Estuary is so unique. A basis for future reporting in providing a snap shot of the current state of the estuary, it sets a baseline against which future changes on the estuary may be identified, particularly those associated with climate change.

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