Proposed guidelines for the computation of spillway design floods in Sweden are described. The guidelines are based on the transformation of extreme hydrological conditions to floods by use of conceptual hydrological models.
Floods computed according to the guidelines are compared to observations for both autumn conditions when rainfall dominates and for snowmelt conditions in spring. The highest floods are in the order of 60% of the proposed guidelines.
Comparisons with frequency analysis show that the computed floods are well beyond the 10,000 year flood according to the Gumbel and Lognormal 2 distribution functions, while the results according to Lognormal 3 are more uncertain.