Geomorphological landslide models for hazard assessment: a case study at Cloudy Hill, Hong Kong

Geomorphological landslide models developed to characterize natural hill slope landslides can assist significantly in the evaluation of natural hill slopes for hazard and risk assessment and for the selection of appropriate mitigation measures. Intense rainstorms in 2000 and 2001 resulted in about 45 natural hill slope landslides on a small area in the vicinity of Cloudy Hill, Tai Po, Hong Kong. A detailed study was carried out to examine systematically the characteristics and mechanisms of the landslides for the purposes of identifying the geomorphological and geological factors influencing susceptibility to landslide occurrence and with the aim of improved hazard assessment for similar hill slopes elsewhere in Hong Kong. Site-specific landslide models were developed from an assessment of the geomorphological setting and landslide characteristics, using a combination of morphological and morphochronological mapping based on aerial photograph interpretation together with field reconnaissance and inspection. Detailed field mapping was carried out for selected landslides following initial review, to confirm the relevant geomorphological factors and document relevant landslide characteristics. An outline of the study at Cloudy Hill is given and the development of the landslide models is presented, together with an overview of how the models were used to assist in the evaluation of natural terrain landslide hazards.