In order to monitor changes in the glaciers in the Bhutan Himalaya, a repeat decadal glacier inventory was carried out from Landsat images of 1977/78 (1980), 1990, 2000 and 2010. The base map of glaciers was obtained by the object-based image classification method using the multispectral Landsat images of 2010. This method is used separately to delineate clean-ice and debriscovered glaciers with some manual editing. Glacier polygons of 2000, 1990 and 1980 were obtained by manual editing on 2010 by separately overlaying respective years. The 2010 inventory shows 885 glaciers with a total area of 64216.1 km2. The glacier area is 1.6% of the total land cover in Bhutan.
The result of a repeat inventory shows 23.30.9% glacial area loss between 1980 and 2010, with the highest loss (11.61.2%) between 1980 and 1990 and the lowest (6.70.1%) between 2000 and 2010. The trend of glacier area change from the 1980s to 2010 is 6.41.6%. Loss of glacier area was mostly observed below 5600ma.s.l. and was greater for clean-ice glaciers. The equilibrium-line altitude has shifted upward from 5170110ma.s.l. to 5350150ma.s.l. in the years 19802010.