River flow records form the basis of flood risk estimates. In Scotland, the Flood Risk Management Act (2009) has the objective of improving flood risk management by improved modelling of river flows taking into account potential future climate change. Wavelet analysis is presented here as a possible method for detecting and comparing trends, investigating spatial heterogeneity and periods of significant variability in non- stationary environmental time series. The results from a wavelet analysis of a set of 9 Scottish rivers confirm a difference in river flow maxima between the East and the West that has been pointed out in previous studies, along with changes in the seasonal patterns that may be linked to external climatic drivers, including the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. Such influences (which act on several time scales, the principal one being annual) are not constant and vary both temporally (being stronger from 1987 onwards) and spatially, with a possible catchment size effect, highlight- ing the importance of assessing flood risk at a regional level. The study is currently being extended to a further 26 rivers to gain a better understanding of the spatial dependence in extreme river flows, which will contribute to the improvement of flood risk management.