Abstract
A time scale for preserving the similarity of beach change processes between prototype and model under the unsteady condition is studied using a series of small- and large-scale experiments. The time scale is proposed as a function of experimental scale. By appling the time scale and the scale-model relationship to model experiments, the temporal beach change such as shoreline change and relative breaker point were well reproduced within the allowable range of experimental errors. Also, time scale is derived theoretically from the continuty equation of sediments and so on. The correspondence between the experimental and the theoretical time scales is discussed. The reliability of the proposed time scale and the scale-model relationship is checked by the movable bed model of beach change in the Ogata coast during a storm.
