Report No. : GEO Report No. 351

Report Title : Factual Report on Hong Kong Rainfall and Landslides in 2020 (2022), 76 p.

Author : V.S.F. Kong, R.C.T. Wai & E.K.H. Chu

Abstract

This report presents a summary of the factual information on rainfall and landslides in Hong Kong throughout 2020. 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 records of landslide incidents reported to the GEO. Supplementary information was collected from the Agriculture, Fisheries and Conservation Department, Architectural Services Department, Drainage Services Department, Highways Department, Housing Department, Lands Department, Water Supplies Department, and the GEO's landslide investigation consultants, namely Fugro (Hong Kong) Limited and AECOM Asia Company Limited.

Rainfall recorded in 2020 at the HKO's Principal Raingauge at Tsim Sha Tsui amounted to 2,395.0 mm, near the mean annual rainfall of 2,398.5 mm recorded between 1981 and 2010. Two Black Rainstorm Warnings were issued on 6 June and 30 September 2020. Eleven Red Rainstorm Warnings and 30 Amber Rainstorm Warnings were issued between 21 May and 5 October 2020, and between 13 February and 5 October 2020 respectively.

Two Landslip Warnings were issued respectively on 6 June and 19 August 2020. A total of 234 incidents were reported to the Government in 2020. Of these, 214 were classified as genuine landslides and seven of them were designated as major failures (i.e. with a failure volume of 50 m³ or more, or where a fatality has occurred).

There were 29 landslides in 2020 with notable consequences. Of these landslides, three led to temporary evacuation of squatter dwellings, one resulted in damage of a village house, two resulted in damage of parked private cars and the other 23 resulted in temporary closure of roads. Other landslides in 2020 primarily affected footpaths or minor access roads, catchwaters and open areas without any significant direct or indirect consequence. No fatality was reported as a result of the landslides.

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