and may be violated by seasonal variation and other temporal trends. In this study, the importance of this violation will be investigated by applying a time-stratified (seasonal) model and a time-varying model (here a non-homogeneous Poisson process) for full-year return value estimates which can be compared to the results of current, non-seasonal methods. In addition, an effort will be made to estimate seasonal return values (eg. Separate summer and winter estimates), since the critical failure modes may be different in different seasons. | 