Report No. : GEO Report No. 273

Report Title : Factual Report on Hong Kong Rainfall and Landslides in 2008 (2012), 209 p.

Author : C.L.H. Lam, J.W.C. Lau & H.W. Chan

Abstract

This report presents a summary of the factual information on rainfall and landslides in Hong Kong throughout 2008. Rainfall information was obtained from the Hong Kong Observatory (HKO) to supplement the information available in the Geotechnical Engineering Office (GEO). Details of the landslides were obtained from the records of landslide incidents reported to the GEO. Supplementary information was provided by the Agriculture, Fisheries and Conservation Department, Architectural Services Department, Drainage Services Department, Fire Services Department, Highways Department, Housing Department, Lands Department, Water Supplies Department, and the GEO's landslide investigation consultants, namely Fugro Scott Wilson Joint Venture and Maunsell Geotechnical Services Limited.

Rainfall recorded in 2008 at the HKO's Principal Raingauge at Tsim Sha Tsui amounted to 3,066.2 mm, which was about 29% above the mean rainfall of 2,382.7 mm recorded between 1971 and 2000. Two Black Rainstorm Warnings were issued on 19 April and 7 June 2008; seven Red Rainstorm Warnings were issued between 19 April and 12 July 2008; and 21 Amber Rainstorm Warnings were issued between 19 April and 5 October 2008.

Five Landslip Warnings were issued between 19 April and 10 July 2008. A total of 868 incidents that occurred in 2008 were reported to the Government. Of these, 863 were classified as genuine landslides and 160 of them were designated as major failures (i.e. with a failure volume of 50 m³ or more, or where a fatality has occurred).

Two fatalities were reported as a result of a landslide triggered by the rainstorm of 7 June 2008. Other notable consequences of the landslides in 2008 included permanent evacuation of 39 squatter dwellings, temporary evacuation of 28 squatter dwellings and temporary closure of 26 buildings. In addition, 56 landslides resulted in temporary partial closure of roads. Another 62 landslides resulted in temporary closure of pedestrian pavements, footpaths or access paths. Fifty four landslides also affected catchwaters, but none of them had any significant direct or indirect impact on the areas downhill of the affected catchwater.

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