##
##
砂防学会誌,Vol.55,No.3,p.50-55,2002
##
荒廃渓流源頭部の砂礫堆積地における
土石流の発生と流動過程の観測
##
Observation of the formation and dynamic process of debris flows in a mountainous debris torrent
##
研究ノート
##
今 泉 文 寿* 土 屋 智** 逢 坂 興 宏**
Fumitoshi IMAIZUMI Satoshi TSUCHIYA Okihiro OHSAKA
##
砂防学会誌 Vol.55 No.3(242)September 2002
##
―#P―
##
―#P―
##
今泉ら:荒廃渓流源頭部の砂礫堆積地における土石流の発生と流動過程の観測
##
Abstract
Taking the Ichinosawa catchments of the Ohyakuzure valley located in the uppermost of the Abe River, the formation and dynamic process of debris flows were observed with a VTR system. The VTR system was able to take a 0.75‐second‐long movie at fixed intervals of 3‐5minutes.
The results are summarized as follows:1) There is great possibility of forming a debris flow on this debris torrent under condition of the rainfall exceeding 30mm in total amount and 5mm in rainfall per 10minutes. 2) Debris flow consists generally of three phases, the primary flow with containing relative an abundant mad, the main flow, and the following flow with reducing the mud concentration gradually. The main flow appears two types, one is muddy flow with a lot of crushed shales, and the other consists of abundant debris of about 20cm diameter. 3) The observed main flow had moved down on the debris torrent floor with a succession of deposition and erosion alternately.
Key words:formation of debris flow, mountainous debris torrent, Ohyakuzure valley, observation with VTR
##