Monitoring thickness change of the Dongkemadi Glacier on Qinghai-Tibetan Plateau using SRTM DEM and map-based topographic data

In this paper we measured the long-term thickness change of the Dongkemadi Glacier(DG) on Tanggula Mountain, Qinghai-Tibetan Plateau, using the Shuttle Radar Topography Mission (SRTM) C-band data(2000) and a digital elevation model(DEM) generated from topographic map(1969). First we check the accuracy of SRTM DEM by comparison at 16 random independent points in surrounding non-glacier area below 5500m a.s.l., then we focus on an analysis of the glacier´s surface thickness change features and a validation of the results using GPS survey data (2007) and DEM(1969) in Xiao Dongkemadi Glacier(XDG). The result shows XDG decreased by an average of 6.15m, or 0.20 m a-1 between 1969 and 2000. We estimate the error of annual thickness change rate to be on the order of 5% compared to the result of field measurement while Da Dongkemadi Glacier(DDG) decreased by an average of 20.74m or 0.67m a-1(1969-2000).