Journal of the Japan Society of Erosion Control Engineering
Online ISSN : 2187-4654
Print ISSN : 0286-8385
ISSN-L : 0286-8385
Volume 53 , Issue 6
Showing 1-15 articles out of 15 articles from the selected issue
  • Yuji SORIMACHI
    2001 Volume 53 Issue 6 Pages 1-3
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Jagannath JOSHI, Hiroshi OMUR, Stefan MAJTAN, Koichi MORITA
    2001 Volume 53 Issue 6 Pages 4-10
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    Total rainfall of 193mm which included maximum hourly rainfall of 50mm, triggered 31 slope failures in a weathered granite area of 0.94km2 in Aburayama Citizen's Forest, Fukuoka, on June 29, 1999. Slope failures' average size and average sediment volume were estimated at 91m2 and 98m3 respectively. Relative cumulative frequencies of slope failures with respect to their area and sediment volume are expressed in the logarithmic normal distribution. Also, relative cumulative frequencies of slope failures with respect to slope gradients and shape ratio are expressed in the normal distribution. 93.5% of slope failures occurred on steep slopes that were artificially cut or filled for road construction. Cut slopes seem more susceptible to failure compared with filled slopes. 42% of slope failures occurred on concave slope, 32% on straight slope and 28% on convex slope. Flow types, which traveled more than two times of the length of rupture surface, were observed at 45.2% sites, and caused more damage.
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  • Tetsuo SAITO, Yuichi ONDA, Ritsuko SHIMOMURA, Maki TSUJIMURA
    2001 Volume 53 Issue 6 Pages 11-17
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    A large-scale sprinkling experiment, using a 625 cm of slope having tubes at middle slope, simulating bedrock fissures, has been conducted to evaluating the role of bedrock fissures on subsurface water movement and runoff generation mechanisms. By drilling through the bottom of the container we made a 6-mm hole on the slope and connected 10 tubes simulating fractures. Each tube had a hemp cord in it, so it has considered the “quasi-fractures” that that resembles hydraulic property of a real fracture surface. Both runoff from the sands and flow in the tubes were measured manually using a measuring cylinder. The data on soil moisture, water-table elevation, and piezometric head were also collected. The runoff peaks were found to be much greater than the tube flow peaks. However the tube flow peaks always coincides with the recession stage of runoff when the runoff was very small ; the volume of tube flow was as much as half of the runoff. This suggests the possibility that the fracture flow in bedrock has a large effect on rainfallrunoff mechanism.
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  • Katsuo SASAHARA, Shintaro YAMASHITA, Takeshi WATANABE, Sadwandharu
    2001 Volume 53 Issue 6 Pages 18-26
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    2 concrete-type slit dams, BO-D 5, BO-D 7 were installed at 1997 in Boyong river, at south slope of Mt. Merapi, Indonesia. Lahar occurred in Boyong river at February, 1998, and those slit dams captured most of sediment of the lahar. Riverbed fluctuation measurement before and after those lahars, rainfall and lahar observation were carried out by Sabo Technical Centre, Indonesia. From those measured data and field measurements by authors, findings as follows are made clear.
    (1) Runoff analysis for the lahars of Feb. 11, Feb. 20 were conducted and it was made clear that runoff coefficient for the Rational Formula of those lahars varies with the scale of rainfall. This fact doesn't coincide with the runoff coefficient=0.75 (constant) for Mt. Merapi volcanic sabo master plan. And the coefficient seems to be increasing in accordance with the rainfall amount.
    (2) It was observed that much sediment deposition occurred behind BO-D 5, while only little sediment deposition occurred behind BO-D 7. As a result of the examination by 1-dimensional riverbed fluctuation model, the reason of the difference between the deposition of BO-D 5 and BO-D 7 was supposed to be caused by sediment hydrograph of the lahar and delay of sediment runoff from BO-D 7 due to sediment storage effect of BO-D 7. It shows the sediment runoff control effect of the combination of several slit dams.
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  • Naomasa HONDA, Takahisa MIZUYAMA
    2001 Volume 53 Issue 6 Pages 27-36
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    It is expected that the greenbelts will play the rule as a buffer zone against sediment disasters in pediments. This paper describes how the greenbelts should be appropriately used in terms of debris flow control. These conclusions are based upon the results of numerical analyses of sediment runoff process observed in actual basins. The Chizuka and Nozakinakagawa Rivers, which drain from the Ikoma mountain system, were chosen for discussions. The numerical analyses were conducted in order to investigate the changes in debris flow characteristics through the reaches of the rivers having check dams. The results of the numerical analyses indicate that the river-bed gradient tends to have a considerable affection the debris flow behavior. The discharge rate of debris flow abruptly decreases as the sediment deposition increases by a decrease in the river-bed gradient. The sediment transport mode then changes from a debris flow into the hyperconcentrated flow or general contact loads. According to these results, in order to withstand debris flow, the greenbelt needs to have a gentle and sufficiently wide slope. If it is actually not possible to have such a greenbelt, debris flow should be controlled using structures such as check dams or embanked channels along with a certain amount of greenbelt.
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  • Katsumi SENOO, Katsunori HARAGUCHI, Toshihiro KIKUI, Shinya YOSHIDA
    2001 Volume 53 Issue 6 Pages 37-44
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    The number of areas in danger of sediment disasters is about 180, 000 in Japan, and countermeasures were carried out only for 20% of them. As a result, many people still have been killed by the disasters. That is the reason why the inhabitants and local governments in such areas need to establish the proper warning and evacuation systems. For that, we have to know when we warn the people of evacuation. The standard rainfall, estimated by the past data of rainfall, is effective to know it. It is decided by the analysis of dangerous amount of rainfall which caused sediment disasters. Though each local government already set the standard rainfall based on the new guideline of Ministry of Construction, it is not precise. This is for how to improve it.
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  • Hideaki MIZUNO, Vittorio BOVOLIN, Noriyuki MINAMI
    2001 Volume 53 Issue 6 Pages 45-54
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    Flume experiments were done to clarify the degree an open check dam lowers peak discharge of a muddy debris flow and a method of estimating the necessary conditions and anticipated discharge rate reduction were proposed. The mixture of sediment and water was set so the simulated muddy debris flow would maintain Froude similarity with the May 1998 debris flow near Sarno, Italy. The flume was 20 cm wide, 40 cm deep, and 500 cm long, and it was set at two different slopes of 5° and 10° . The wooden dam models included three slit types with widths of 5 cm, 10 cm, and 15 cm and three square conduit types with sides of 5 cm, 10 cm, and 15 cm. After the sediment and water were mixed for 6 minutes with two electric drills equipped with a special propeller in the upstream space from a gate, the gate was opened manually to create a muddy debris flow in the flume. Sampling boxes on a roller at the bottom end continuously collected the muddy debris flowing from the dam models. Both the slit and conduit dams lowered the peak flow volume. The smaller the dam dimensions, the lower the peak discharge rate. Surges were observed forming upstream from the dam models. Equation of continuity, momentum equation, and energy equation for positive surge obtained equations representing the surge formation conditions and discharge rate. Their application to the experimental results showed that the calculated values generally reproduced the test results.
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  • Makoto YOSHINO, Shinji KUSAKA, Toru TANIGUCHI
    2001 Volume 53 Issue 6 Pages 55-60
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Kazuyuki SATO, Shinji UEHARA, Takahisa MIZUYAMA, Syun-ichirou KASAI
    2001 Volume 53 Issue 6 Pages 61-65
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Sigekiyo TABATA, Kimio INOUE, Tomoya HAYAKAWA, Shiori SANO
    2001 Volume 53 Issue 6 Pages 66-76
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    The Totsu-Kawa Hazard that occurred in August 1889 was triggered by heavy rainfall in Nara Prefecture, Kii peninsula, central Japan, and claimed the lives of 1492 persons (in Nara and Wakayama Prefecture). Many landslides occurred in mountain slopes and the landslide debris dammed up mountain valleys to form many large landslide dams. After few hours to 30 days, the landslide dams then collapsed, and the big flood rushed down along the Totsu-Kawa valley into the Shingu City. The Arida-Kawa Hazard that occurred in September 1953 was triggered by heavy rainfall in Wakayama Prefecture, Kii peninsula, and claimed the lives of 1046 persons. Many landslides dams were formed and collapsed, and the big flood rushed down along the Arida-Kawa valley. We studied the process of formation and collapse of many landslide dams.
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  • [in Japanese]
    2001 Volume 53 Issue 6 Pages 77-81
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Kiyoshi SANO
    2001 Volume 53 Issue 6 Pages 82-87
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Masaaki NAKANO, Yoshikazu SHIMIZU, Takao YAMAKOSHI, Katsuei KASAI, Tsu ...
    2001 Volume 53 Issue 6 Pages 88-94_2
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Masayuki WATANABE
    2001 Volume 53 Issue 6 Pages 95
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese]
    2001 Volume 53 Issue 6 Pages 96
    Published: March 15, 2001
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    Download PDF (119K)
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