Severn Estuary

What did the Severn Estuary ever do for us?


The results of a unique, forward-looking study which demonstrates the relative values of the goods and services provided across the Severn Estuary, and shows the part the natural environment plays in underpinning both our economy and our wellbeing, has been launched this week.

The Severn Estuary and inner Bristol Channel is one of the UK’s largest natural wonders. Submerged and exposed twice per day by the second highest tidal range in the world and fed by freshwater from the Severn, Usk and Wye and Avon upstream, its mosaic of habitats includes energy rich mud flats, creeks, saltmarsh and shoreline. Such diversity means the estuary harbours a wealth of wildlife which is constantly changing as the seasons come and go, and the tides ebb and flow.

However, the estuary is not just a natural wonder, it has been a centre of trade and industry for centuries and is the home of the great port cities of Bristol and Cardiff and more recently has become the focus as a site for tidal energy. Balancing the various demands on the Severn Estuary to ensure its sustainable future as both an important wildlife site and as a resource for developments of economic and social significance, requires a deep understanding of the ‘goods and services’ the estuary provides. Estimating the relative values of such competing demands in a complex system is essential.

A project, funded by the Natural Environment Research Council (NERC) Marine Renewable Energy Knowledge Exchange Programme, was carried out jointly by PML and the RSPB. It set out to identify locations within the Severn Estuary and Bristol Channel where key ecosystem services are found, these include: ports and shipping; carbon storage; flood risk management; wild food, fisheries and migratory fish; and archaeology and a sense of place. The project then mapped these services and explored the potential for valuing and quantifying the levels of benefit for each service.

Assigning values to goods can be fairly straightforward. Fisheries, for example, can be valued by market price of catches and expenditure into local communities from recreational fishing, but there are also less tangible benefits such as the simple existence of fish species or the value to future generations. Carbon storage mitigates the impacts of climate change and so the economic value of saltmarshes and mudflats in capturing carbon is very real. Likewise the part played by estuarine habitats in preventing flood damage has a genuine value measured against the cost of having to build artificial structures to do the same job. The value of shipping and the goods it carries, and the jobs it creates through ports and harbours seem obvious benefits, while putting a value on the emotional ties people feel towards the Severn Estuary is extremely difficult. The project final report: Ecosystem service mapping in the Severn Estuary and inner Bristol Channel, brings these aspects together for a wide range of stakeholder groups, is launched today and can be found here.

Mark Robins, Senior Policy Officer of the RSPB said “The big prize ahead will be to align a nature restoring and sustainable development future in and around this vast complex estuary, including the tidal energy opportunities of the Severn. We hope this new study that showcases the many benefits that the estuary provides us with will help lead to wise decision making by all interests to win this big prize.”

Dr. Graham R. Daborn of the Acadia Centre for Estuarine Research, Acadia University, Nova Scotia, and an expert on the management of multiple uses of estuaries welcomed the report: “Estuaries represent the most important ecosystem on Earth for people, but are often not fully recognized for the many ways in which they benefit society. This study clearly shows how estuaries with a large tidal range offer a great variety of important ecosystem services to human populations. The study also reminds us that there is a limit to the degree to which we can afford to modify the natural physical processes of an estuary in order to reap a benefit: development of any new asset such as tidal energy, port facilities, or enhanced fisheries, for example, requires that we understand the ecosystem well enough to forecast the effects this may have on other natural aspects, or other ecosystem services, he said.”

Dr Tara Hooper, from PML, added “Trying to assign values to some ecosystem goods and services is very difficult, but it does bring the often competing demands on an estuary, for example, into perspective. In the past, obvious goods, such as fisheries and transport have often taken on an importance over other aspects, which are less easy to assess. What we are now seeing is that some of the ’hidden’ functions of estuaries have significant values, comparable or greater than the more visible industries. By using this approach on the Severn Estuary we have gained a clearer picture of what it actually does for us. Knowing this we can now plan how the estuary can be used for such things as renewable energies and flood prevention, while not destroying the less tangible but equally important cultural, historical and natural aspects that make the Severn Estuary a place cherished by local communities and visitors”.

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