On sandy shores, drift of sandy sediment, which affects habitat characteristics of the bottom environment, is one of the important environmental factors for burrowing benthic animals, especially at saturated environment in lower shoreline. But no simple method for measuring drift has been proposed. In this study, we proposed new simple methods to characterize the drift by measuring the change of the bottom current velocity and the amount of bottom drift. In order to evaluate these measurements as critical physical environment, we also investigated the lower limit of the distributional zone of gammaridean amphipod Haustorioides japonicus and the occurrence of ripples on the sandy bottom. The results of this study demonstrated that the both of two methods, one by measuring the bottom current velocity and the other by measuring the amount of bottom drift, were useful to estimate the drift and both of the measurements decreased immediately in the bottom area with ripples. The lower limit of the main distributional zone of H. japonicus correspond to the occurrence of ripples. This avoiding distribution pattern of H. japonicus from ripples was discussed in relation to its lifestyle and sediment reworking by drift.
