著者

中島 勇喜 末 勝海

出版者

THE JAPANESE FORESTRY SOCIETY

雑誌

日本林学会誌 (ISSN:0021485X)

巻号頁・発行日

vol.55, no.8, pp.250-252, 1973-08-25 (Released:2008-12-18)

参考文献数

6

著者

末 勝海 中尾 博美 陶山 正憲

出版者

九州大学

雑誌

九州大学農学部演習林報告 (ISSN:04530284)

巻号頁・発行日

vol.47, pp.235-269, 1973-03

被引用文献数

1

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Serious damages occurred in the area of headwaters of Hitotsuse River in Miyazaki prefecture extending 10,000 ha., which areas are those including the Miyazaki District University Forest of Kyushu University caused by the typhoons No. 19 and No. 23 in 1971. Land slide damages as much as 400 places were recognized by means of aerial photographic interpretation. Total amount of the landslides was estimated about 200,000 m^3, countless forest roads were cut, and two check dams were destroyed. It is thought that most of these damages are due to the unprecedented storm rainfalls amounting to 1,300 mm and 700 mm in No. 19 and No 23 typhoons respectively, but it is recognized remarkable difference of damaging degrees in various districts and it is construed from the difference of natures in various soils. Damages are developed remarkably in the area of topographic features where gradients show the angle of 30~40 degrees. From our investigations on land slides occurred in cutting slope of forest road between Okochi and Ozaki, we recognized most of land slides tend to arize in newly earthworked zones and within 50 m from line of valley center. Considering roadway diagraph problem, failure percentage has been increased at the places such as the length of cutting slope of 4.77m, gradient of ground surface of 31.5 degree and cutting area of 13.54 m^2. Highest failure percentage was recognized in the conditions as follows: length of cutting slope 8.50 m, gradient of ground surface 42.5 degree, cutting area 32.5 m^2. In the Iwaya valley consisted of granite bed mostly, a land slide occurred in the scale such as inclines of 300 m, width of 50 m and soil amount of 50,000 m^3. Land slide flew down as debris flow having velocity of 4~11 m/sec and it caused considerable erosion at the place of steep slope of valley floor, but at gentle slopes contrary made the debris depositin. One check dam seemed to have been damaged gradually for several years, another was thought damaged by single attack of debris flow, and our two dimension calculation of stability indicated the area of cross section was insufficient for debris flow.

著者

末 勝海 垣内 重三郎

出版者

九州大学

雑誌

演習林集報 (ISSN:03760707)

巻号頁・発行日

vol.4, pp.13-26, 1955-03

被引用文献数

1

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To investigate the landslide and mud-and-rock flow damages caused by Nos.5,12 and 15 Typhoons of 1954, a on-he-spot survey was made of the bar{O}k bar{o}chi District, Sh bar{i}ba-mura, Miyazaki Prefecture.(Fig.1). The area of this district is 5700 ha, and the geological formation is of the mesozoic system. The relief-grade per l km square has a mean value of 360 m (Fig.2). The damages were mainly due to the rainfall of Typhoon No. 12, which amounted to 1411.1 mm. Phtos 1-7 and Figs.3 and 4 show the traces of mud-and-rock flows. The total volume of debris produced by the landslides shown in Photos 8-13 was about $2-3 \times$10^5$ $m ^3$, and it was deposited on the bed of the ravine as shown in Photos 7 and 14. Fifteen lives and thirty-four houses were lost in the flood.