WEAKLY SCALED PHYSICAL EXPERIMENTS IN SURFACE PROCESSES: A REVIEW VIA THE EXAMPLE OF BARRIER-ISLAND RETREAT (Invited Presentation)

By ‘weakly scaled’ we mean experiments for which some or all of the relevant dimensionless parameters cannot be matched to field cases. This includes nearly all physical experiments in stratigraphy and geomorphology that are done at reduced scale. We have argued elsewhere that for such cases, scale independence is a more useful basis for experimental design than the classical approach of matching dimensionless parameters. The fundamental basis for this approach is developing theoretical and observational criteria for recognizing scale independence and determining its limits. There is no general method for doing this, but in this talk we illustrate some of the possible approaches using a set of recent experiments at St Anthony Falls Laboratory. The experiments focused on the response of delta-front barrier islands to rising sea level, and the main result is that the migration is unsteady even if the sea-level rise is constant. Our focus will be on the extent to which the wave and sediment dynamics that matter in this problem display sufficient scale independence to make the results applicable to the field.