著者

谷口 房一 小川 恒一 水山 高久 藤田 正治 小杉 賢一郎 扇 行徳

出版者

砂防学会

雑誌

砂防学会誌 : 新砂防 = Journal of the Japan Society of Erosion Control Engineering (ISSN:02868385)

巻号頁・発行日

vol.52, no.2, pp.27-30, 1999-07-15

参考文献数

4

被引用文献数

3

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Typhoon 7 hit Honshu on September 22, 1998. This storm brought about a certain amount of local damage in the path of the typhoon. Trees in the southern part of Nara Prefecture were blown down. Field survey and analysis of aerial photographs taken after the storm were carried out to determine some of the characeteristics of the trees blown down. Along narrow gorges the blown down trees on the steep slopes lay scattered in the direction of the downward grade. The blown down trees on slopes in the open areas lay in the same direction as the blast of the wind.The most trees blown down entirely from their roots and a few trees were broken at the middle of their trunks. The structure that check the outflow of the downed trees and the incidental landslides or debris flow sediment was proposed to be built from the logs of rather large diameters available at the sites.

著者

佐藤 創 長坂 有 浅井 達弘 寺澤 和彦

出版者

社団法人 砂防学会

雑誌

砂防学会誌 : 新砂防 = Journal of the Japan Society of Erosion Control Engineering (ISSN:02868385)

巻号頁・発行日

vol.58, no.6, pp.11-17, 2006-03-15

被引用文献数

4

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We quantified the woody debris on the flood plain of the Appetsu River, watershed area is 287.9 km², by Typhoon 0310, Etau. This typhoon caused heavy damage, especially in the Hidaka and Tokachi districts of Hokkaido. We established 61 study sites in the river basin and investigated the size, species, and freshness of woody debris in a sampling plot in each study site. We used aerial photographs to estimate the volume of woody debris outside the study sites. The volume of woody debris totaled 46, 260 m³. The deposits were greatest in the upper river basin in the northern area. Of the total volume, 76% originated from landslides on mountain slopes or bank erosion, and the remaining 24% was from riparian forests. Of the woody debris, 15% were conifers and the remaining 85% were broadleaf trees. An estimated 74% of the volume came from trees that were living just before Typhoon 0310 struck, and the remainder was old fallen timber. Of the woody debris, 12% of the trunks had diameters under 10 cm, 57% were 10 - 30 cm, 28% were 30 - 50 cm, and 3% were over 50 cm.