Historical aerial photographs and digital photogrammetry techniques to investigate the development and evolution of the Chin Coulee landslide in Alberta

ABSTRACT: The Chin Coulee landslide is situated on the northern slope of the Chin Coulee reservoir, Southern Alberta. The landslide has a volume of approximately 2 million cubic meters and Alberta Highway 36 is located upslope from the crest of the landslide. This highway has been affected by landslide retrogression to the extent that realignment has been necessary to maintain the highway operational. Alberta Transportation actively monitors the Chin Coulee landslide, however, resource allocation for geohazard management needs to meet public safety and highway operation requirements, as well as resource availability. Understanding the landside mechanisms, triggers and potential evolution are fundamental for defining cost/effective management strategies. This paper presents the use of historic aerial photographs in combination with modern digital photogrammetry tools to investigate the development of the Chin Coulee landslide, and its evolution towards its current state. This approach makes use of important legacy information available in the province.