Flood retention in Skurdalsåa River, Gudbrandsdalen, Norway

The Skurdalsåa River is one of many steep tributary rivers to the main river Gudbrandsdalslågen. These tributary rivers often have relatively small catchments, and therefore responds quickly to precipitation events and to snow melt. They are steep and often characterized by erosion and sediment transport during extreme events, which in some cases may transform into debris flows. Roads, houses, a school, a kindergarten, and a sports facility are situated adjacent to the lower part of the Skurdalsåa River, and the infrastructure has experienced repeated flood damage in recent years. The river course has several bottlenecks, mainly caused by location of buildings and other infrastructure, but also due to culverts and bridges not dimensioned for the present (or the future) flood situations. Trees and other debris blocking the river at these bottlenecks have caused problems during flooding. Skurdalsåa River has its outlet from Svintjønna lake. By reconstructing an old existing dam located at Svintjønna's outlet, the lake can increase its retention capacity during flood situations and thus distribute the flood water in Skurdalsåa River over a longer time period to avoid flash floods (reduce the peak flood).