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Volume 53 (2000 - 200･･･
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Volume 53, Issue 4
Displaying 1-19 of 19 articles from this issue
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Kanichi KANEGAE2000 Volume 53 Issue 4 Pages 1-3
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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Nobutomo OSANAI, Noriyuki MINAMI, Shinji TAKESAKI, Kyoichi MATSUMURA, ...2000 Volume 53 Issue 4 Pages 4-15
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSWhen the torrent conservation works were carried out on the alluvial fan and at the bottom of ravine plains, it was a general procedure to shape the channel rectangle by simply fixing its bank with concrete revetment. Recently, however, such works strongly require harmonization with the surrounding environment, therefore, it is considered important to diversify the section of the channel. One method, we believe, will be useful in securing the long wings of groundsels without fixating the low water channel, which then forms a desirable cross-sectional shape. And to be sure of the effectiveness of the riparian trees on the rectification of flood water, we carried out a hydraulic model experiment. We later found that the bank erosion was strongly affected by the growth of the alternating bars at the center part of the channel. Therefore, the roughness effect of the riparian trees to centralize the main current should be utilized after arranging the channel work structure in order to reduce the effects of the alternating bars. Moreover, a numerical simulation model was tested to calculate the width etc. of the maximum bank erosion and the effect of the riparian trees. In the case where the sediment provided from the bank corresponded to the hydrodynamic force and the resistance against the wave force, the two-dimensional sheet flow model which transport the sediment as bed load could, to a certain extent, reappear in the erosion process.View full abstractDownload PDF (20678K) -
Naomasa HONDA, Takahisa MIZUYAMA2000 Volume 53 Issue 4 Pages 16-22
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSThe effects of sabo buffer greenbelts to control debris flow depend chiefly upon both the trunk diameter of the trees and the space between the trees. A large tree has great resistance against debris flow. Sabo buffer greenbelts with little space between trees well catch debris flow. However, both the trunk diameter and the space between the trees are incompatible with each other if sound growth of forest is expected. In order to resolve this problem, this paper proposes the use of log crosspieces attached to trees in sabo buffer greenbelts. According to the results of the calculations, the use of crosspieces in such a mode is capable of specific resistance against specific intensity of debris flow. For example, one crosspiece about 3.5m long and 36.0cm in diameter can resist debris flow running at about 5.0m/sec. The results of the calculations also prove that the effects of the use of crosspieces in sabo buffer greenbelts depend chiefly on both the collision intensity of debris to the trees in the greenbelts and the resistance of the roots of those trees.View full abstractDownload PDF (2472K) -
Takashi YAMADA, Noriyuki MINAMI, Hideaki KIKUCHI, Ikuto MIURA2000 Volume 53 Issue 4 Pages 23-29
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSTo 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° ).View full abstractDownload PDF (4610K) -
A case study model for Oshima County Yamaguchi PrefectureKatumi SENOO, Tooru TAKAHASHI, Yoshinori ARAKI, Kohei FURUKAWA, Takahi ...2000 Volume 53 Issue 4 Pages 30-37
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSAn examination on debris flow warning and evacuation system based on GIS (geographical information system) was developed to reduce human injury or death from debris flow due to heavy rain. The system examination was done in Ooshima County of Yamaguchi Prefecture where debris flow occurred in June, 1979. The geological composition of this area is granite. A developed model using a personal computer can issue information about the rainfall and the danger of debris flow occurrence. It also has a damage assumption simulation function to warn against high torrents of danger. Because the judgment of warning and evacuation was completely visual, the system proved to be effective.View full abstractDownload PDF (11642K) -
Yuko KATO, Yuichi ONDA, Takahisa MIZUYAMA, Ken-ichiro KOSUGI, Ai YOSHI ...2000 Volume 53 Issue 4 Pages 38-43
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSRainfall and runoff were monitored in 10 th small catchments underlain by Granitic rock basins and Mesozoic sedimentary rock basins upstream of Ibi River in Gifu Prefecture. Following findings were obtained (1) Runoff peak response time (it's time lag) is longer in Mesozoic sedimentary rock basins than in Granitic rock basins. (2) Large changed runoff duration curve were obtained only in P 1 and P 2 catchments of Mesozoic sedimentary rock basins. Runoff characteristics of Granitic rock basins are one pattern, but these of Mesozoic sedimentary rock basins are two patterns. This suggests that Granitic rock basins are enough to obtain one basin, but Mesozoic sedimentary rock basins are not enough to do it.View full abstractDownload PDF (6023K) -
Noriyuki MINAMI, Yasuhiro DOI, Nobutomo OSANAI, Shinji TAKESAKI, Yasuy ...2000 Volume 53 Issue 4 Pages 44-51
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSHeavy rain attacked northern part of Tochigi prefecture at the end of August, 1998. The rain caused a serious flood disaster, which killed 5 people, missing 2 people, flushed bridges and damaged tons of agricultural products along Yosasa River. The flood eroded the surrounding riparian forest and produced a large amount of woody debris. Some bridges that cross over the Yosasa River trapped woody debris and the flood water flushed their abutments and piers. To mitigate these kinds of disasters, it is important to understand the characteristics of woody debris, its source, yield, deposit positions, etc.. However, data are deficient in spite of the efforts of researchers. The following information were obtained after executing a field survey and studying the aerial photos.
1) Much of the woody debris was produced from riparian forest.
2) Emergence types of woody debris were by slope failure, by bank erosion and by riverbed erosion.
3) Woody debris was deposited at the bridges, at the upstream of riparian forest and on the riverbed.
4) A cluster of woody debris moved downward along the river channel by repeating the cycle of “Clogging→Dam up →Failure→Moving down”.
5) Bridges were damaged by the dense woody debris, so the girder heights and the pier spans were not large enough for the debris to flow down.
A dense riparian forest which developed in and around the river made it difficult to distinguish the actual boundary of the river till the disaster. It is important to determine the land use near rivers with consideration of the previous flood data, the topography, the location and the priority of land use.View full abstractDownload PDF (9310K) -
Shinji TAKESAKI, Noriyuki MINAMI, Nobutomo OSANAI, Toshihiro HASHINOKI ...2000 Volume 53 Issue 4 Pages 52-57
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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Hideaki MIZUNO2000 Volume 53 Issue 4 Pages 58-61
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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Kenji MIWA2000 Volume 53 Issue 4 Pages 62-64
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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Osamu HIROI, Hidemi YOSHIMURA, Takuroh KIMURA, Nobuo ANYOJI2000 Volume 53 Issue 4 Pages 65-75
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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Makoto URA, Minoru SHIMOIDA, Toshiharu ARISAWA, Tatsuya OCHIAI, Ryota ...2000 Volume 53 Issue 4 Pages 76-83_2
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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[in Japanese]2000 Volume 53 Issue 4 Pages 84-85
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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[in Japanese]2000 Volume 53 Issue 4 Pages 85-86
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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[in Japanese]2000 Volume 53 Issue 4 Pages 86-87
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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[in Japanese]2000 Volume 53 Issue 4 Pages 87-88
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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Kiyoshi HONDA2000 Volume 53 Issue 4 Pages 90-92
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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Satoshi TSUCHIYA, Hideaki MARUI, Masanobu KIMURA2000 Volume 53 Issue 4 Pages 93-94
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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Masaharu FUJITA2000 Volume 53 Issue 4 Pages 95
Published: November 15, 2000
Released on J-STAGE: April 30, 2010
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