著者

Kimio INOUE Toshio MORI Takahisa MIZUYAMA

出版者

Japan Society of Erosion Control Engineering

雑誌

International Journal of Erosion Control Engineering (ISSN:18826547)

巻号頁・発行日

vol.5, no.2, pp.134-143, 2012 (Released:2012-12-27)

参考文献数

19

被引用文献数

2 3

---

Large landslides or debris flows caused by heavy rainfall or earthquakes often block rivers in mountainous areas and form landslide dams. The area upstream of the landslide dam is submerged under water and the downstream area is flooded when the landslide dam breaks. In recorded history, as many as 22 landslide dams have formed upstream of the Shinano River and the Hime River, in the northern part of Nagano Prefecture in central Japan, and all except three have subsequently broken. This abundance of landslide dams is probably caused by the geotectonic background of this area, which is located at the western end of the “Fossa Magna” major tectonic line. In this study, we examined three large historical landslide dams and outburst disasters in the north Fossa Magna area.

著者

Laurentia DHANIO Takahisa MIZUYAMA Ken'ichirou KOSUGI Agnes RAMPISELA

出版者

Japan Society of Erosion Control Engineering

雑誌

砂防学会誌 (ISSN:02868385)

巻号頁・発行日

vol.61, no.4, pp.32-38, 2008-11-15 (Released:2013-09-02)

参考文献数

8

---

The collapse of caldera walls of Mt. Bawakaraeng on 26th of March 2004 in South Sulawesi is one of the largest mass movements in the history of Indonesia. The collapsed material, calculated at approximately 232 million m3, covers 8 km of the upstream part of Jeneberang River. The main purpose of this research is to evaluate the magnitude of the impact on the change of basin and how the impact decreases over time. A given amount of rainfall produces less discharge after the collapse and peak flows which normally occurred in the months of January are now found in the months of March. Before the collapse, every daily amount of rainfall corresponds to 0.6 value of daily discharge, though in 2006, it decreased to 0.45. Daily discharges are mostly low flows (less than 5 mm/day) except in the year of the collapse (2004). After the collapse, medium flows occurred more frequently and high flows (flow of over 90 mm/day) occurred in less frequency and lower values. Analysis of turbidity and discharge relationship at Bili-bili Dam located 31 km downstream of the collapse may be applied to understand the sediment exhaustion and the basin's potential rates of recovery. Bili-bili Dam's maximum turbidity rate increased significantly from 407 Nephelometric Turbidity Units (NTU) to 125,159 NTU after the collapse and turbidity's respond to discharge alters after the collapse. Peak turbidity rates normally fall faster than the discharge falling limb ; nonetheless after the collapse, both values fall by approximately 50% daily.