抄録
A method for determining grain size from digital images of sediment proposed by Rubin was applied to field data and experimental data. Its accuracy is poor under sediments with the high sorting coefficient because fine-grained sand may be burned under coarse-grained sand. It is possible to estimate the grain size unless water permeates the sediment surface for the wet grained sand. But the grain size measured by digital images is nearly equal to that by sieving, The experimental data showed that the sorting process would be generated in a short period, and then fine-grained sand is deposited on the offshore side and coarse one on the onshore side under depositional wave actions.
