Cwm Ivy: Where the sea comes in

Aerial view of Cwm Ivy marsh

Cwm Ivy marsh is a small parcel of land on the coast of North Gower. It was claimed from the sea to be used as farmland in the 17th Century and was protected by a sea defence which over the years increased in size and strength. In 2014 the sea wall breached and the sea is reclaiming the land, transforming Cwm Ivy freshwater marsh to saltmarsh.

Our Shifting Shores report held one clear message … as a nation we can no longer build our way out of trouble on the coast. This means at sites such as Cwm Ivy we no longer try to defy nature by holding back the tide, instead we let nature take its course. 

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Why allow the sea in?

In places like Cwm Ivy, rising sea levels are having a big impact. As an organisation, we’d made a decision as part of the Shifting Shores policy to no longer hold back the sea on our land and so at Cwm Ivy the sea now has reclaimed its place and flows across the previously grazed fields. This animation explores the two possible future outcomes at Cwm Ivy.

Breach in the sea wall

In November 2013, Cwm Ivy sea wall was showing signs of distress. Repeated heavy rain had welled the inland stream to unprecedented levels and the sluice gate designed to drain the marsh simply wasn’t able to remove the water fast enough. 

The pressure of water forced a small hole under the wall and the following winter of storms, rain, high tides and storm surges began to widen the hole and allow significant amount of sea water in to the freshwater marsh. 

In August 2014 the summer storms finally caused the wall to fail, effectively ending its time as a sea defence. 

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Cwm Ivy from the sky

Witness the transformation of Cwm Ivy from grazing pasture to wildlife-rich tidal salt marsh. Triggered by a winter of bad storms, this video shows a bird’s eye view of the early stages of the transition, with footage before and after the sea wall was breached.

Looking forward

Thanks to the vision of the Shifting Shores report, of allowing coastal realignment to happen as naturally as possible we're focusing on managing the change in habitats from freshwater marsh to saltmarsh.

Almost as soon as the breach occurred the vegetation underwent a radical change. The farmland grasses died back within days and the trees rapidly began dropping leaves and most were standing dead wood by spring 2015.

Was this a problem? Visually this was not an improvement over the lush greens we used to see, however this transition phase, unsightly as it was, was temporary, until the saltmarsh plants started to take over. 

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First few months after the breach

Fast forward to March 2015 and the first signs of life from saltmarsh plants could be seen; delicate scurvey grass, Salicorina (samphire) species, sea blight, thrift and sea spurrey. By June the whole marsh was alive with the vibrant greens of a healthy saltmarsh. Watch the video to witness the transformation for yourself.

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Three years on from the breach

Cwm Ivy marsh, in just three years, has transformed, by the winter of 2017, we had a fully functioning saltmarsh at Cwm Ivy. Watch the video to hear about the transformation and habitat gains at Cwm Ivy.