A field investigation was performed at the Tonegawa river-mouth and the south Kashimanada coast whose littoral environment changed drastically owing to the construction of river, port and shore protection facilities. Littoral drift with various time scales was described on the basis of analysis of sediment samples as well as measurements of waves, currents and turbidity around the river-mouth. Particle size analysis and measurements of γ-ray radiation were carried out for sediment samples collected along the shoreline and vertical core samples taken from the sea bed, revealing the temporal scales of sediment sorting and sedimentation processes. Measurements at the river-mouth were performed just after a flood, in which the resuspension process by waves, tidal flows and ocean currents was described for fine sediments deposited by the flood. Schematic diagrams of coastal morphological processes in recent 50 years were presented.