Abstract
In Japan with its many mountains, debris flow disasters on alluvial fans, as exemplified by the 1982 Nagasaki Disaster, are major problems. To prevent such disasters, it is necessary to predict areas likely to be flooded by debris flows. It is also necessary to ascertain the effects produced by countermeasure works for debris flows when arranging them so as to protect lives and properties. Following matters were studied by a debris flow simulation model. (1) Confirmation of the reproducibility of the simulation model with regard to an area flooded by a debris flow through comparison with hydraulic model tests of a debris flow on an alluvial fan. (2) Evaluation of the effects of the countermeasure works for debris flows. (3) Influence of step time of the calculation to results. (4) Comparison with other simulation models. As a result, it is confirmed that the simulation model is adequate for practical use in predicting the areas flooded by debris flows and evaluating the effects of the countermeasure works for debris flows. It also can be used in making future erosion control plans.
