CURRENT STATUS OF CONCRETE REVETMENT IN THE UPPER RIVER BASIN OF CENTRAL AND NORTHERN KYUSHU, JAPAN, AND RELATED FACTORS

The current status of concrete revetment was investigated in the upper river basin in the central and northern parts of Kyushu, as basic information on river ecosystem conservation. The ratio of concrete revetment reached nearly 20% per riverbank distance. The ratio of concrete revetment was high in rivers with low elevation and small slope. In these rivers, the ratio of concrete revetment was further increased by arranging the roads along the rivers and changing the surrounding land. The rivers flowing through pelitic schist had a high ratio of revetment because the rivers had low elevations, small slopes, and often had roads near the rivers. Considering the conservation of the ecosystem in the basin, it is thought that upper rivers with low elevation and small slope and rivers in pelitic schist have a high degree of modification, and it is necessary to focus on conservation and restoration in the future.