In order to grasp the effect of the gentle slope revetment works to exert on the biodiversity at a tidal river, we surveyed at the tidal area in the Gokase River in Miyazaki Prefecture about the distributions of physical environments (ground levels, grain diameter and ignition loss of bed material) and the benthic communities at both of the soil-covered gentle slope revetment (A), and the vertical dry stone pitching revetment (b). As the results, the physical environments were similar in a transverse direction at the B section but the A section were successively varied. The kinds, and rare species of benthos, especially insects were rich at the A section rather than the B section. The results suggested that the gentle slope revetment works had improved biodiversity.
