Report No. : GEO Report No. 210

Report Title : Review of Slope Surface Drainage with Reference to Landslide Studies and Current Practice (2007), 65 p.

Author : T.H.H. Hui, H.W. Sun & K.K.S. Ho

Abstract

This report presents the findings of a review of the current practice in respect of design and detailing of slope surface drainage provisions, with particular reference to lessons learnt from the relevant landslide studies. Inadequate implementation of the recommended good practice in some instances has led to poor practice, such as inadequate number of drainage channels, undersized drainage channels, inappropriate channel layout or connection detailing, etc. These have been found to be contributory factors in some landslide incidents.

Key issues that warrant special attention are highlighted with a view to promoting further enhancement of the practice in respect of the design and detailing of surface drainage provisions for slopes. which include:

1. proper assessment of the environmental conditions and the overall land drainage of a site in a holistic manner,
2. sufficient redundancy of the surface drainage provisions to cater for uncertainties,
3. adequate attention to the proper detailing of slope surface drainage provisions, and
4. adequate site control by suitably experienced supervisory staff and proper construction of the surface drainage provisions, including timely and suitable amendments made to the detailing and layout to cater for the actual site conditions as revealed during construction.

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