Monday, 19 November 2007

A Chance for the Cuckmere Estuary

The Environment Agency has recently put out the document “Cuckmere estuary: draft flood risk management strategy” – essentially an outline of a set of alternative proposals for managing the Cuckmere estuary.

The significant feature here is that the Agency’s preferred option is to achieve flood risk management by allowing the estuary to return to a more naturally functioning system.

I strongly support this approach.

The SWT has consistently supported an approach to flood risk management that works with, rather than against, natural processes. The Cuckmere estuary is a particular location where this sort of approach is very appropriate.

The estuary is a good place for wildlife, and a good place for people to visit. This is why it is designated a Site of Special Scientific Interest and is also a tourist hot spot. The Wildlife Trust itself has an education facility there and we make good use of the environmental assets of the valley. However the valley has been severely degraded by past flood defence. The straight canal cut across the valley has isolated the famous meanders, prevented flooding in the flood plain and degraded the habitats alongside the river. There would, rightly, be an outcry today if anyone proposed such a straight heavy-engineered structure in this attractive natural setting.

The impetus to taking a different approach, however, comes from several directions.

First these old flood defences are likely to fail in the near future, so an alternative approach is needed.

Second, with climate change, incidents of flooding are likely to increase. Sea level rise will increase flooding from the sea and increased storm frequency will result in more flood water flowing down the river.

Third is the realisation that with sea level rise we get coastal squeeze. Old flood defences prevent nationally important coastal habitats migrating inland so they erode away with loss of wildlife. If coastal habitats disappear then the full force of incoming waves will hit the sea defences, causing them to erode as well. Thus maintaining hard sea defences where they are requires far stronger, more imposing and unsightly structures than in the past.

Fourth, ironically, the use of modern technology means that the Agency can more accurately model the results of different management options. Therefore, smart use of technology means that they can model how nature works and work with it, rather than constantly battling against it. Smart use of technology means we can work more with nature, rather than against it.

There may be some who fear a change towards a more naturally functioning valley. As humans we sometimes do not like to think of a treasured landscape changing, but change is inevitable and when we compare the alternatives the restoration of a naturally functioning system is by far the best option. The other end of the spectrum is a continuation of hard sea defences, the loss of coastal habitats, the loss of the meanders as they silt up and a re-enforced, stone-lined canal across the valley. Opportunities to restore the wetland habitats in the valley would be lost for at least a generation and the degraded landscape would be unlikely to attract the affection of either visitors or local people.

Even official documents refer to the “deterioration of the meadows as mud takes over”, with concern about the effect to visitor numbers, illustrating a view that all change is bad. If coastal habitats were so unpopular then one would expect areas like Pagham Harbour, Chichester Harbour and the sea front at Bosham to be deserted because of their ugliness! In practice, of course, the opposite is true.

So we have the choice – a highly expensive concrete gutter (paid for by us, the tax payer) delivering virtually no benefit, or a more naturally functioning system with evolving and improving wildlife and landscape.

In practice, of course, there are several in-between possibilities. A more naturally functioning system can still have works done within it to influence the direction of natural change – a managed retreat option. These are progressively more expensive than leaving things to nature as the level of human influence increases. Option 3b, as presented by the Agency, is one of these. The best approach is probably to start from the perspective of a natural system and then add in sensible levels of influence as resources become available.

The alternative – that of hard defences – is more of an all or nothing approach. It is very difficult to add in a level of naturalness when the starting point is a hard engineered structure. Concreting over the Cuckmere estuary is not the answer.