STUDY ON SURVEY METHOD GRAVEL BED OF SURFACE AT BEDROCK RIVER

Abstract

 In the Muka River, the Tokoro River system, in 2016.8, the flood caused outflow gravel bed of surface and the exposure of the volcanic ash layer. Sudden degradation of riverbed occurs, and lowering of the stability of the low-water revetment and the bridge with that. In this study, we considered survey method for understanding the gravel bed of surface at the bedrock river. As a result, it was found that the combination of surface wave survey and ground-penetrating radar survey can be a method to determine the thickness of sand and gravel layers more accurately by interpolating the results of both surveys.In addition, it clarified the problem that extend the range of applicability of geophysical prospecting at river area.