Why has the longest river in Ireland flooded? The floods along the River Shannon were caused by heavy rainfall from four back-to-back storms. It began with Storm Abigail in mid-November, then continued with Storm Barney, Storm Clodagh and, most recently, Storm Desmond. Although Desmond has abated, water that had soaked into land took a long time to flow into the Shannon. The situation has been exacerbated by further heavy rainfall in recent days.
Who is affected by the flooding? The worst of the flooding has occurred in Cos Mayo, Leitrim, Galway, Roscommon, Westmeath, Offaly, Clare and Limerick. Towns along the Shannon, including Ballinasloe, Portumna, Athlone and Carrick-on-Shannon, have been particularly badly hit.
What is being done for residents? The Government has set aside €15 million to support those affected by the floods. Of this, €5 million will be made available to small businesses and the remaining €10 million will assist homeowners. On the ground, local-authority staff, the Civil Defence, members of the Defence Forces and the Irish Red Cross have been supporting those affected by the floods. Other bodies, such as Irish Water and the HSE, are also providing advice and assistance in flooded areas.
Why has sewage mixed with the floodwater? The rising water has inundated sewerage systems in some flooded areas. As it rises, the water mixes with the raw sewage, which then flows up through street drains.
Are there other factors? The primary cause of the flood has been heavy rain. The last major flooding along the Shannon occurred in 2009, when homes and businesses flooded. These coincided with the end of the building boom , when construction was commonplace on traditional flood plains in some areas. Building on flood plains displaces floodwater that might otherwise have been able to flow into the plain. The management of the River Shannon has also been a contentious issue for decades, with claims that a number of managing agencies have differing interests.
Has climate change played a role? Although it can't be said with certainty that the latest flooding was caused by climate change, scientists have for years been predicting increasingly frequent extreme weather. When more than 100 homes flooded in Athlone in 2009, homeowners were told that it was a once-in-100-years event. Six years later a similar event has unfolded. Locals say that the River Shannon was at a record low for October in Athlone just two months ago.
Why is the ESB providing forecasts for water levels? The ESB has a major interest in the Shannon because it uses the river to power some of its hydro-electric station at Ardnacrusha, Co Clare. It controls the flow of water along the Shannon at the Parteen Weir in Co Tipperary, downstream from Athlone. During flooding, the release of water at Parteen has to be carefully managed to prevent too much water flowing into the lower Shannon while at the same time alleviating some pressure upstream.
What is being done in the long term? Catchment flood-risk assessment and management studies were introduced nationally in 2011 to assess 300 flood-prone areas. The programme is central to the Government's strategy for the reduction and management of flood risk in the medium and long term. The study is due to be completed next year, when flood-management measures are expected to be announced.
Have the worst of the floods passed, at least? The River Shannon is expected to continue to rise over the coming days. Met Éireann is warning of heavy rainfall over the weekend. There is a delay between the time rain falls, when it runs off the land, and when it enters the Shannon, either directly or through its tributaries. The latest flooding is expected to continue into next week. The water table will also remain very high for quite some time, leaving areas susceptible for some time to flooding in the event of heavy rain.
