Local non-stationary flood-duration-frequency modelling

Abstract

Flood-duration-frequency modelling is an extension of standard flood frequency analysis that takes into account the multi-duration aspect of flood hydrographs. The key assumption of this approach is that the parameters describing the flood frequency distribution for any flood duration do not change over time. In reality, however, as a consequence of local and/or global anthropogenic activities, stationarity of hydrologic records cannot be assumed. New methods that take into account the non-stationarity of hydrologic records and that can properly deal with time-dependent parameters of flood frequency distributions need to be developed and used in practice. This study introduces formal aspects of non-stationary flood-duration-frequency modelling. The presented approach uses trend analysis to identify time-dependent components of the model and to predict their changes in the future. The significance of the time-dependent parameters is reflected in the structure of the model. The approach is illustrated on a study catchment in British Columbia, Canada. © 2007, Taylor & Francis Group, LLC.