Report No. : GEO Report No. 271

Report Title : Detailed Study of the 7 June 2008 Landslides on the Hillside above Yu Tung Road, Tung Chung (2012), 124 p.

Author : AECOM Asia Company Limited

Abstract

This report presents the findings of a detailed study of the natural terrain landslides that occurred on the hillside above Yu Tung Road, Tung Chung Northern Lantau, on 7 June 2008 during a Black Rainstorm.

Yu Tung Road was affected directly by two major channelised debris flows that occurred in catchment Nos. 24 and 30 at the northern and southern end of the northwest facing hillside above the road respectively. The largest channelised debris flow from catchment No. 30 resulted in about 3,500 m³ of debris reaching Yu Tung Road. Both westbound lanes of Yu Tung Road were closed for more than two months. The other channelised debris flow from catchment No. 24 resulted in about 250 m³ of debris being deposited alongside the road. In addition, minor quantities of fine material were washed onto the road from other drainage lines within the central portion of the hillside from catchment Nos. 25, 26 and 29. Subsequent outwash resulted in debris being carried onto the Tung Chung Eastern Interchange and flooding of Cheung Tung Road below. No casualties were reported as a result of the landslides.

The key objectives of the study were to document the facts about the landslides, present relevant background information, summarise the detailed landslide debris trail mapping reports for selected landslides and establish the probable causes of the landslides and debris movement processes. The scope of the study comprised desk study, site reconnaissance, detailed field mapping, and engineering geological mapping. Recommendations for follow-up actions are presented separately.

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