Nature's solutions to flooding need more respect

ANOTHER LIFE:IN TIMES LIKE THESE, one is guiltily glad to be living on a hill above the sea. When the Atlantic unleashes its latest torrents, recycling rain from sky back to ocean, at least the water stays in the ravine beside us, surging downhill under the bridge. The odd clack of colliding rocks echoes up to my window.

To dwell on a glaciated hillside, its fences and meadows merely skin-deep, the old boulders breaking through, is to soak up (sometimes literally) the interface of weather and land. But there are places in Ireland where this becomes obscure, hidden under concrete or beneath the earth itself. Topographic levels, too, can get lost or forgotten once the sea is out of view.

The idea that the Shannon basin could be drained in some way haunted the hopes of generations of farmers. In 1954, after a specially disastrous flood, the government brought in an expert from the US Army Corps of Engineers – tamers of the Mississippi right down to New Orleans – if not always infallible. Colonel Louis E Rydell spent four years working out the channels to be dredged in the Shannon mainstem and its tributaries. He finally conceded that the problem was immense, needing many further studies and moved on to tackle the Indus in Pakistan.

Thinking about rivers and floods has changed a lot since then, with a lot more respect for nature’s own systems. The arterial drainage by the OPW that canalised so many Irish rivers in the 1960s is now regretted for brutal destruction of bank and riverbed habitats and wildlife: there are better ways of doing it. The EU’s Water Framework Directive, compelling the current plans for managing whole river basins – the Shannon among them – sets the needs of wildlife alongside those of human settlement.

The EU’s even newer Floods Directive demands flood hazard maps by 2013 and flood risk management plans by 2015. It not only makes the obvious points about not building new houses in flood-prone areas, but urges, where appropriate, restoring flood plains and wetlands. The OPW, Ireland’s lead agency in managing flood risk and remedy, has lifted its head from physical dredging and building walls and weirs to take the more proactive approach, like advising planners and public, shown in websites such as www.floodmaps.ie.

The obdurate problems of some landscapes are nowhere more dramatic than in the karst country of the Gort-Ardrahan area of south Galway. Karst is deep bedrock limestone full of holes, from cave systems, surface turloughs and swallow-holes to finger-thick fissures in the rock. Karst has created the botanical treasure of the Burren, Co Clare, but also, periodically, appalling floods in the farming lowlands to the north. Here, water flowing off the hard sandstone heights of Slieve Aughty disappears underground into the cavernous limestone of the lowlands.

This subterranean labyrinth fills with rain from a vast area, and expels it underwater at Kinvara on the coast. Its deep rocky apertures are fixed and often choked with rubbish, so rainfall backs up inland. There is no surface outlet to Galway Bay. To carve a channel would disrupt turlough habitats prized for European nature conservation, but the huge cost and geological uncertainty of doing so, in such fissured terrain, have been far more decisive – and never more so than in the present recession. In one major investigation, following a flood in 1990, it was thought that once Coillte’s young spruce forests on Slieve Aughty had grown to a closed canopy, they should help absorb extreme rainfall. Since then a broad swathe of clearfell – almost 300 hectares – was given over to the big Derrybrien wind farm.

The vegetation of Ireland’s upland rim, now recovering from overgrazing, will be crucial to the flow of water in the cascades threatened for the future. As in everything to do with floods, the picture is not simple. Conifers on blanket peat make poor commercial sense: a lot of them grow badly and blow down in storms. Ploughing drains to plant seedlings releases more carbon and methane from the peat, and rushes water downhill. On steep slopes, the stability of the blanket bog itself is threatened by extreme downpours.

Coillte is leaving a few western bog plantations, mostly a tangle of lodgewood pine, to go wild and regenerate as best they can. Loftier notions of reforesting the hills with native trees have their advocates, and research to show which species would do best: sessile oak and birch, holly and rowan, with Scots pines – Ireland’s original conifers – as punctuation. It would take a long time, a lot of money, and we’re broke. As for “restoring wetlands” – all those marshy bits at the edge of town, filled with lorryloads of rocks and rubble for foundations. Dig it up again? This isn’t China.

EYE ON NATURE

Recently I came across four or five wood pigeons which took off from around an injured pigeon with an open wound in its craw. On a closer look I noticed pieces of neatly shredded leaf carefully stacked inside the craw. Were the other pigeons nursing it?

Denis Quinn, Killala, Co Mayo

Hardly, but pigeons eat leaves as well as seeds, and would have some in its craw.

We had some trees lopped recently and came across a bundle of wire netting, old wire coat hangers and other metal strips. We wondered if magpies would be capable of putting together such a collection of heavy metals for a nest.

Mary Knight, Dalkey, Co Dublin

Indeed they would.

There is a very large wasps’ nest in the attic of my house and I wondered if it would be safe to remove it myself.

Gerry Harrison, Castleknock, Dublin 15

Leave it until a little later in the winter to make sure that all the wasps have died.

I saw two cormorants perched on the old laundry chimney at the Nine Arches near the Dodder, and later fishing at the Dropping Well weir – very handsome birds if a bit on the funereal side.

Mary Kavanagh, Ranelagh, Dublin, 6

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo. E-mail : viney@anu.ie. Include a postal address