複合型土石流の発生に関与する地形要因についての統計的解析

抄録

To evaluate the topographical factors contributed to the occurrence of debris flow due to deep-seated slope failure, a multiple discriminant analysis was performed based on a case of an actual past deep-seated slope failure which induced debris flow and landslide dam by using topographical factors such as “riverbed gradient at the inflow area of the collapsed mass, ” “angle of the flow of the collapsed mass into the torrent, ” “gradient change ratio, ” etc. as explanatory variables. The results discriminated between the occurrence and the non-occurrence of a deep-seated slope failure which induced debris flow and clarified various topographical factors effecting its occurrence and the weight of each one.
The results show that the most influential factor is “angle of the flow of the collapsed mass” with “riverbed gradient at the inflow area of the collapsed mass” as the next important factor, the “angle of the flow of the collapsed mass” that distinguishes a deep-seated slope failure which induced debris flow ranges from 10° to 62° (average value : 31.4° ), and the “riverbed gradient at the inflow area of the collapsed mass” ranges from 6° to 25° (average value : 15.1° ).