Flood defences are far from watertight

Richard Tol

December 01 2009 04:44 AM

FLOODING has afflicted the country for two weeks now. The worst is probably over. A full investigation should uncover what happened, what went wrong, who did the right things, and what should be done next. There are many things we do not know yet, such as the adequacy of flood insurance or possible silt contamination. Nonetheless, a number of lessons can be drawn at this stage.

Floods are caused by three things: bad rains, bad planning and bad luck. There will be an element of surprise in any flood. The best water management system cannot prevent all floods, and the best emergency plans cannot avoid all damage. In this case Ireland seems to have been hit by bad planning first and severe weather second. As someone who has studied flood risks and flood management in many countries (but not Ireland), the following things struck me.

The amount of rain that fell in October and November was exceptional, while July and August were wet too. But it is well known that rainfall varies greatly from year to year. The amount of rain this year was within the range that could, and should, have been anticipated. Met Eireann maintains excellent, easily accessible records on rainfall. In this case, the floods were caused by an accumulation of severe rainfall over a protracted period.

But Met Eireann does not publish data on how much water is in the surface and groundwater system. In fact, no one does. Data on water levels is the joint responsibility of Met Eireann, the Office of Public Works (OPW), the Geological Survey of Ireland, the Marine Institute, the Electricity Supply Board (ESB) and the Environmental Protection Agency in collaboration with the local authorities. As is often the case, joint responsibility means no responsibility. Lesson One: a single authority should collect and collate data with the purpose of issuing flood warnings.

Among the six bodies, the ESB stands out. Companies perform better if focused on their core business. The ESB should make and sell electricity. But there is more than corporate management at stake here. Hydropower is more profitable if the reservoirs are full, while flood management is easier if they are empty. There is a clear conflict of interest between the ESB as a power company and as a flood-management authority. Lesson Two: the ESB should be relieved from its duties in flood management.

The floods caught many people by surprise. Sandbags followed the water. There is no need for this. Water flows to the lowest point, and most valuables can be rescued with even an hour's warning. The current floods are not the first to hit Ireland. The Government spends almost €1bn a year on research. But high-quality, comprehensive elevation maps and flood models are still not ready. Lesson Three: we need to develop a flood prediction system.

It is not enough to predict floods. Warnings should reach the right people in time. It is not acceptable to release water from reservoirs in the middle of night without alerting those downstream, but the problem is much wider than that. As I write, floods may or may not threaten Dublin. None of the six organisations responsible for water data has a website where I can check whether my home is at risk. Nor does Dublin City Council. There is not even a telephone number to call. The best source of information is RTE, but that information tends to be general and vague. In other countries, the authorities actively inform the public via the internet, by text message or even by going from door to door. This requires resources and staff training -- including flood drills. Lesson Four: we need a flood warning system.

The call for improved planning in Ireland is not new. We cannot undo past mistakes. It will be a while before new homes and offices will be built on a substantial scale again. Before then, efforts to map flood risks should be finalised. Conclusions should be drawn. In areas of high flood risk, no new buildings should go up and existing ones may need to be torn down. In areas of medium flood risk, new buildings should be built at their owners' risk -- with no insurance, and no government compensation available. For a change, such rules should be enforced, perhaps by an independent body. Lesson Five: land zoning must be taken seriously.

Climate change is likely to bring more winter floods to Ireland. Flooding will occur more frequently. This means Ireland's drainage system needs to be reviewed and, if necessary, overhauled. This is not easy. In winter, we want to move the water faster to the sea. In summer, we want to keep the water longer to mitigate drought. More frequent dredging may be enough, but we may need deeper rivers with more dams and reservoirs. Other solutions are conceivable too. Lesson Six: a review of water flows is necessary, and probably some major civil engineering works too.

Flood management is not simple. Support for measures like those listed above will retreat with the waters. But only bold measures will prevent the return of the floods.

Professor Richard Tol is with the Economic and Social Research Institute (ESRI) in Dublin and the Vrije Universiteit in Amsterdam