Laboratory Study of Beach Nourishment Behavior

Abstract

A study of beach nourishment viability was performed to determine the relationship between selected wave and beach characteristics and project performance. Laboratory tests of idealized beach nourishment projects were conducted, with emphasis on project planform changes that arise due to gradients in longshore sediment transport. Nine test cases were designed with monochromatic, nominally shore-normal waves. The idealized beach nourishment projects were compared with trends predicted by simple analytical and numerical shoreline evolution models. Mathematical and laboratory results are in general agreement regarding beachfill behavior at laboratory scale. The rate of evolution, however, is overpredicted for the model nourishment projects when standard calibration factors are applied. This is expected, based on numerous previous laboratory studies of longshore sediment transport. The effects of breaking wave height, wave period, beach slope, beachfill length, and initial planform on the rate at which sediment diffuses from a beach nourishment project are evaluated based on laboratory results. In summary, beachfill longevity was found to be positively correlated with project length and wave period, and negatively correlated with breaking wave height and beach slope. One test suggests that projects with a trapezoidal planform retain sediment better than equivalent rectangular projects.