RISK-LEVEL ASSESSMENT OF SMALL-SCALE MOUNTAIN STREAMS USING A DIGITAL ELEVATION MODEL

抄録

 In recent years, rainfall intensity in Japan has shown an upward trend, and sediment inflow disasters caused by mountain streams are increasing in number. As there are a significantly large number of mountain streams along railway lines, considerable time and effort are spent on local surveys for identifying dangerous mountain streams. Additionally, as there are a variety of diverse factors such as terrain and different geological features that collectively determine the hazard posed by mountain streams, risk-level assessments are not consistent among technicians. Above all, the risk-level assessment of upstream areas located in positions widely separated from the railway tracks and dispersed over a wide area require a huge amount of time and effort, and there may be a large disparity among the assessments made by engineers. Therefore, in this paper, we describe a simple method of evaluating the risk level of mountain streams in upstream areas using uniform criteria, without requiring local surveys. In concrete terms, we developed a scoring sheet that could assess the risk level mainly using quantitative data from a digital evaluation model (DEM). Through numerous comparisons, it was shown that the evaluation obtained using the DEM-scoring table was almost the same as the evaluation provided by local surveys.