Extensive strategy needed to combat flooding

We can do more to plan for the effects of storms and bad weather, writes John Tyrrell

We can do more to plan for the effects of storms and bad weather, writes John Tyrrell

So we are talking about the weather again after another storm warning, deluges and more flooding. There are numerous news stories doing the rounds, of misfortune, damage and endurance that are feeding an appetite for the dramatic as well as concern for our future well-being.

But was it such an extreme and unusual event? Even in Irish terms it was a very long way from any kind of record. In two days, rainfall totals achieved a "mere" 50-60mm at best (Kilkenny, Casement and Cork airports), although undoubtedly there must have been wetter localities.

Compare these with falls of 150-250mm in 24 hours that have been recorded on other occasions on our island. We were nowhere near the extremes of our own climate.

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So too with the wind. Unlike floods in many parts of mainland Europe, winds frequently contribute significantly to our own floods.

But again, they were pretty "normal" for severe storms (gusts reached 55 knots at best - only half way towards any sort of real Irish extreme). However, together with the high spring tides, the low pressure (marginally raising sea levels a little further), not to mention the land saturated by days of preceding rain, these conditions locally overwhelmed us in the form of floods.

Flooding is part of our history and it is certain it will be part of our future. Despite the need to acknowledge this and to respect the powerful forces at work that produce them, there is much we can do to limit flooding and the extent of the damage it causes.

Prague, another European city prone to floods, may have some lessons for us. In the major floods of 2002, its flood model predicted a specific flood level and a predetermined management strategy was implemented for that level of flooding. This included 10-foot watertight panels along each bank to contain the floodwater.

These were relatively inexpensive, temporary structures that were no impediment to the magnificent city vistas at normal times. Cork, and other Irish cities and towns, might well have benefited from such a provision last week.

But in the medium term we need a more comprehensive approach to flooding than this. We should consider incorporating a climate hazard audit into our formal planning process.

This would require a systematic analysis of weather-related hazards when zoning land in local area plans and in developing regional policies. Then housing need not be sited where air pollutants gather in calm cold, wintry weather, or on suburban hilltops where roofs get damaged in high winds and heat losses are maximised, nor structures built where flooding is inevitable. Roads would not be widened or newly built where wind, flood, fog and other dangerous conditions occur.

Development also changes the risks of weather hazards such as floods - sometimes for the worse. More roads, roofs, concrete and tarmac mean the rain will simply flood down our streets and highways making them awash with water until it reaches our doors. Whatever the development, it should not worsen a hazard.

John Tyrrell is a lecturer in climatology in the Geography Department of University College, Cork.