Floods, new design-flood criteria and dam refurbishment in Sweden

摘要

The serious flooding that occurred in Sweden in 1983 led to the establishment of Floedeskommitten. Its main task was to prepare new guidelines for determination of design floods for Swedish dams. Floedeskommitten released its final report in 1990. In the guidelines, the design flood for a dam is obtained through transformation of extreme climatological and hydrological conditions. The new guidelines result generally in higher design floods for existing dams than they were constructed for and many spillways have too low discharge capacity. Based on the design-flood guidelines, the hydropower sector has worked out dam-safety guidelines, RIDAS, and application instructions governing the dam safety practice in the country. As recommended, all class I (high hazard) dams have to be designed to discharge the design floods. Several refurbishment examples are given to illustrate the on-going work on dam safety carried out by Vattenfall AB. The refurbishment of the dams considers as a whole technical, economical and environmental aspects.