FIELD OBSERVATION ON BED FORMS FOR MOUNTAINOUS REGION IN SHIGENOBU RIVER

Abstract

River bed-forms in mountain region are characterized by steep slope, wide range of grain size distribution of bed materials and relatively small water depth to the bed roughness, which cause ‘stair-like’ or ‘transverse rib’ bed forms. Low water channel and the surroundings have many kinds of vegetation and grain-size variation such as large gravel and small sand in the mountain region. Therefore, the mountain region gives good environments for living things. And, one more characteristic of the mountain river is that temporal variation is extremely large. In the present study, the stair-like or the transverse limb bed in mountain rivers with steep slope bed and with wide range of grain size of bed materials, was surveyed at a test field section of the Shigenobu river from1992 until 1998, and the characteristics of the bed forms and their change with time are discussed.