Monitoring Landslides In China: Recent Advances

Efforts to reduce the human and economic losses associated with landslides in China have proven to be extremely successful largely due to the recent work of local scientists. For instance, annual deaths attributed to landslides rose from 278 in 1990 to 1573 in 1998 and have progressively dropped to 682 in 2005. This reduction is primarily the result of expanded mapping, monitoring, mitigation and public outreach activities. Extensive hazard mapping in China indicates that the south central area of the country, corresponding to the eastern Tibetan Plateau, is the most susceptible to landslide problems. Characteristically this region has been subject to pronounced uplift and extreme climate resulting in deeply incised, over-steepened valleys, which coupled with unstable deposits (both bedrock and surficial sediments), high precipitation and seismicity as well as high population density, creates conditions favourable for pronounced landsliding. Cooperative studies by the China Geological Survey and the Geological Survey of Canada have focussed on the detailed analysis of large failures in the Sichuan Province area. Current monitoring by the Chinese includes traditional mapping, D-GPS, inclinometers, extensometers, rain gauges, and piezometers. To complement this repertoire, Canadian InSAR technology (RADARSAT) has been applied to improve our understanding of the nature and extent of landslides in the area. Here we discuss landslides in Danba County, in particular the monitoring efforts at the Jiaju landslide; located on an important cultural setting of national relevance. Installation of 10 corner reflectors in early 2007 and satellite image analysis over several months allows us to better evaluate the hazard and minimize the risks associated with slope failures in the region.