DAM ENGINEERS have played down fears voiced by climate experts that earthfill structures would be more likely to collapse in the face of increasingly heavy rainfall.
Authors of a new report, Assessment of potential effects and adaptations for climate change in Europe, fear earth slopes will be destabilised as a result of increased saturation caused by heavier, more prolonged rainfall.
The report, published last month by the Jackson Environment Institute for the European Commission, predicts rainfall will increase by up to 4% per decade. It says the water content of earth-fill structures is set to rise significantly over the next few decades. Groundwater levels will also rise, affecting foundations.
Engineers disputed the claims. Binnie Black & Veatch technical director Andrew Rowland said there was a theoretical risk that higher porewater pressure on the downstream slopes of embankment dams could result in structural failure.
But he added that modern dams were designed with a far larger surface water drainage capacity than required and would be able to cope with foreseeable increases in rainfall, and extreme events. All old dams have been inspected to ensure they measure up to current performance standards, he added.
Increased porewater pressure is likely to result in localised failures on downstream slopes, requiring increased maintenance, said Brown & Root chief dam engineer John Gosden. Unchecked, these could, over a long period, lead to more serious damage.
The report says that by 2050 there will be far wetter winters and drier summers. Rainfall will be concentrated in prolonged, heavy downpours rather than spread through the winter months. Severe weather events will be five times more frequent .