Glacier evolution in the South West slope of Nevado Coropuna (Cordillera Ampato, Perú)

Abstract

Glaciers not only reveal information about climate change, they are very important as a water supply for the population who is living around, this implies a risk, glacial hazards and risk associated with glacier retreat, such as ice avalanches, new glacier lake formation and glacial lake outburst floods (GLOF), constitute a major cause of severe catastrophes in populated mountain areas (Huggel et al., 2004). The management of these risks is a complex task involving analysis, evaluation, and communication as well as prevention and mitigation (Greminger 2003). The investigation and monitoring of the glaciers makes them valuable for climate research, and their future evolution can be predicted. The aim of this project was to reconstruct the glacial phases in the SW slope of Nevado Coropuna in order to generate quantitative information of surface areas and ELAs as a first step for the analysis of glacier evolution and the achievement of valuable information of the changes that have happened. The specific conclusions of the present study are: (1): Moraines on the SW slope of Nevado Coropuna served as the reference to reconstruct the geometry of paleo-glaciers in LLGM glacial phase. Modern glaciers from 1955 and 2007 were also delimited using aerial photographs for 1955 glaciers and Google Earth image mosaic for 2007 glaciers. (2): The surface areas of the glaciers were calculated from their delimitation. The results indicated that the total surface has retreated 2,3 km2 from 1955 to 2007, this is a reduction of the 21,5% of the glaciated surface. The deglaciation rate is 0,044 km2/year (44.000 m2/year). (3): The ELAs AABR of the glaciers were calculated from their delimitation. The results show an altitudinal shift of the ELA of 13 m from 1955 to 2007 and 984 m from LLGM to 2007. The analysis shows ELA AABR altitudes of 5834 m for actual glaciers (2007), this data match with the results of other authors. (4): Is assumed that ELAs vertical shifts are caused by changes in temperatures. By analyzing the ELAs vertical shift is possible to study the climate change. The temperature shift from LLGM to 2007 in the NW slope of Nevado Coropuna was 8,26ºC/km (0,0082ºC/m).