Country & Garden: Bring back flood plains - to stop flooding

Nature's way, rather than pricey river works, may be best at reducing damage from any winter deluge.
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The Independent Culture
SNOW MAY be the element we most associate with winter, but water poses a far greater threat for millions. As the colder months loom on the horizon, householders, authorities and insurance companies are bracing themselves for the misery, criticism and costly claims that will inevitably accompany the first heavy cloudburst.

The Environment Agency certainly takes the threat seriously. It's just spent pounds 2m in order to boost awareness of the problems, while towns such as Bewdley in Worcestershire are looking at emergency flood defences to guard against a repeat of last year's 16ft rise in the River Severn's normal flow.

Such moves would astound our ancestors. Far from regarding the root cause of flooding - flood plains - as problems, they were treated as useful allies, and now it seems we may have to return to our former views. Such a move would have undoubted environmental benefits too, providing vital feeding grounds for countless species.

Until recently unwanted flooding was countered simply by restricting building to higher ground. But, as cities grew, suitable sites alongside navigable rivers became scarcer. One answer was to build costly walls; but a cheaper alternative was to allow the river to burst its banks upstream, covering large areas of farmland with water that acted as a vast storage system (look, for example, upstream of Oxford, Worcester and Salisbury).

There were other benefits. Early farmers discovered fields which are submerged for the colder months provide some of the best grazing. The water keeps the ground from freezing while fertilising it with silt. As the waters recede, grass grows earlier and more lushly, providing crucial grazing in "the hungry gap" at winter's end.

So, it was only a short step to creating water meadows by leaving rivers to follow a meandering route, encouraging vegetation and building sluice gates. While water meadows, such as those of Hampshire and Wiltshire, are a fascinating insight into our past and are rich in wildlife, Roger Martin, the director of the Somerset Wildlife Trust, says their environmental value is limited, not least as they cover quite small areas. Instead he points to larger flood plains as critical to the survival of many creatures, particularly in southern England.

Just as water meadows keep the ground warmer, so migrant ducks and geese fleeing the icy clutches of the Continental winter appreciate the rich grazing in the vast semi-flooded areas which ought to accompany our larger rivers. Catcott Reserve in the Somerset Levels, for example, typically draws in flocks of 5,000 teal and widgeon each winter. Not only this, the generally frost-free conditions keep the ground soft enough for insect eaters like woodcock, snipe and even wrens.

A second environmental benefit is that flood-prone land is unsuitable for intensive farming. Most grain crops dislike waterlogged ground and while in the past water meadows may have made good grazing for hardy breeds of sheep and cattle, it is unsuitable for modern dairy herds. High-yield milkers like Friesians depend on fast-growing - and fertiliser-loving - rye grasses. These dislike water-logged ground, and anyway the artificial nutrients on which they depend are washed out of the soil by too much water. So, fields that flood are among the last to be improved and are thus rich in a wide variety of native grasses and flowers that vary in speed of growth and palatability, producing the kind of tussocky conditions beloved by ground-nesting birds such as lapwings and snipe.

Unfortunately, since the Second World War, shifts in human activity have transformed Britain's flood plains. Agriculture has changed beyond recognition, with the emphasis firmly on productivity. Understandably, farmers with riverside fields dislike to see potentially valuable land lie useless for several months a year.

Encouraged by successive Governments, many farmers have drained waterlogged land that's then converted either to arable use or replanted with faster- growing grasses. More importantly, it also opens up sites to non-agricultural uses.

Growing prosperity means there has been a huge rise in housing demand - particularly for estates of middle-class detached homes with large gardens. Building on relatively flat ground reduces costs, so former flood plains can seem ripe for development. To see this in practice, one needs merely to take a train journey out of any major city - but the Paddington-to- Bristol line provides one of the best examples.

Such building leads inevitably to problems. No matter how good its artificial drainage, a flood plain will always retain its potential to fill with water. Naturally planners recognise the risks and insist on the inclusion of complicated defences in such projects, but, according to Mr Martin. "If you don't use flood plains to store water you have to get rid of water as quickly as possible," he explains. "But this only moves the problem downstream where they have to work out a way of moving ever-increasing quantities, leading to a cycle of destructive engineering."

Last spring the inhabitants of Kidlington on the outskirts of Oxford became all too aware of such dangers when, without warning, they were inundated by water rushing down the normally slow-moving Cherwell after upstream "improvements" in flood defences. Likewise, in the autumn the people of Bewdley in Worcestershire might have had more warning, but who can adequately protect their home against the Severn rising 21ft in just a few hours?

There seems to be a growing recognition that improving water flows isn't the answer to winter rains. Not only does it place towns downstream at risk and deprive wildlife of valuable habitat, but it also leads to summer water problems too.

Flood plains not only absorb excess winter water, but store it too, releasing it slowly as river levels subside, mitigating summer drought. This certainly was the view of a recent House of Commons Agriculture Select Committee which decided that many flood defence schemes were a waste of money. "Protecting what we've got - maybe even increasing the acreage to some extent - would undoubtedly help wildlife," says Mr Martin. "But we've got to be realistic: we're never going to reverse the riverside developments that have already occurred - that would be more than the most bug-eyed naturalist would expect or want."

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