Report No. : GEO Report No. 368

Report Title : Factual Report on Hong Kong Rainfall and Landslides in 2021 (2024), 60 p.

Author : C. Lam, V.S.F. Kong & E.K.H. Chu

Abstract

This report presents a summary of the factual information on rainfall and landslides in Hong Kong throughout 2021. 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 AECOM Asia Company Limited and Fugro (Hong Kong) Limited.

Rainfall recorded in 2021 at the HKO's Principal Raingauge at Tsim Sha Tsui amounted to 2,307.1 mm, about 5% lower than the annual normal of 2,431.2 mm recorded between 1991 and 2020. Two Black Rainstorm Warnings were issued, each on 28 June and 8 October 2021. Six Red Rainstorm Warnings and 27 Amber Rainstorm Warnings were issued between 1 June and 8 October 2021, and between 4 May and 13 October 2021 respectively.

Two Landslip Warnings were issued respectively on 28 June and 8 October 2021. A total of 170 incidents were reported to the government departments in 2021. Of these, 146 were classified as genuine landslides and 13 of them were designated as major failures (i.e. with a failure volume of 50 m³ or more, or where a fatality occurred). None of these major failures involved a fatality.

There were 15 landslides in 2021 with notable consequences. Of these landslides, one led to temporary evacuation from a village house, one resulted in damage of a temporary storage structure, one resulted in damage of the brick column of the entrance corridor of a house and the other 12 resulted in temporary closure of roads. Other landslides in 2021 primarily affected footpaths or minor access roads, catchwaters and open areas without any significant direct or indirect consequence. No casualty was reported as a result of the landslides.

Download Document(s)