Landslide Attributes Study in the Nelson Forest Region:
RESEARCH PROJECT

Location: Nelson Forest Region

Client: Ministry of Forests, Forest Sciences, Nelson, BC

Objective: To determine terrain attributes responsible for development-related landslides and to use this information to improve classification criteria for terrain stability mapping.

A regional study was made of landslides in the Nelson Forest Region from 1996 to 2001. The study covered an area of approximately one million hectares. Approximately 1700 landslides were inventoried by air-photo interpretation, and of these, over 300 were field checked by Carol Wallace Consulting. Several attributes, including slope morphology, local hydrology, indicators of instability, and contributing factors at each site were assessed.

Preliminary results show that forest development in the study area increases landslide frequency in the order of 10 times over natural rates. Roads, not clearcuts, caused most landslides inventoried in this study. Drainage concentration and diversion by roads is the most common cause of landslides on new roads, and on older roads, road-fill failures are the most common cause of landslides.