Fluctuaciones en la extensión de los glaciares del nevado Cololo (14 º 50’ L.S. – 69 º 10’ L.W.) a partir de datos de TM/LANDSAT-5

Abstract

This paper presents surface fluctuations of glaciers in the Nevado Cololo, Bolivia, from 1975 to 2011, determined using TM/Landsat-5 images. The glacier areas were determined for the years 1989, 1997, 2008 and 2011. The application of NDSI (Normalized Difference Snow Index) and NDWI (Normalized Difference Water Index) indexes were the basis for the development of an algorithm for glacier identification. Elevation data from a topographic map allowed obtaining a DEM using ordinary kriging. In 2011 only 48 of the 122 glaciers identified in 1975 remained. The small glaciers (<0.1 km²) with low max- imum altitude have been the ones most affected by this loss and, currently, there are no ice masses below 4,626 meters ASL. Nevado Cololo glaciers covered ~25 km² in 2011, an area loss of 42.02% when compared to 1975. This loss occurred in all slopes, regardless of their orientation, but glaciers of the east faces were the ones most affected. Even the largest glacier, face towards SW, lost 21.6% of its total area. The glacier division and rock outcroppings in their internal parts suggest ice thinning. The intensification of the ablation process is probably the cause of glacier loss in this region.