Abstract
Field observations were carried out at several times for one semi-diurnal cycle and for one fortnightly cycle in the well-mixed estuary, the Rokkaku River, in order to investigate the mechanism of suspended sediment transport and water quality variation. In the estuary, a turbidity maximum is formed and moves toward up- and down-stream with erosion and deposition of sediment according to tidal action for the semi-diurnal cycle. For the fortnightly cycle, salt intrusion varies with tidal stage and variations of suspended solids concentration have such a tendency that the concentration becomes lower during neap tide and higher during spring tide. Water quality on dissolved matters is easily characterized with water volume accumulated from the head of the estuary.
