DIOLAIUTI G., D’AGATA C., MEAZZA A., ZANUTTA A. & SMIRAGLIA C.
Recent (1975-2003) changes in the Miage debris-covered glacier tongue (Mont Blanc, Italy) from analysis of aerial photos and maps
Pages 117-127
Abstract
The present study aims at identifying any changes in volume and thickness of the Miage Glacier tongue (Mont Blanc Massif, Italy) during the period 1975-2003. The Miage glacier developed the largest part of its debris cover over the last century, now found mostly between the glacier terminus (about 1850 m a.s.l.) and the upper ablation tongue (c. 2400 m a.s.l.) on a surface area of c. 4 km 2 The period examined (1975-2003) addresses climate conditions which were glacier-favourable (around the . 1980s), as well as glacier-unfavourable (since the early to mid-1990s), thus contributing to an understanding of the behaviour of debris covered glaciers under a changing climate. The analysis was based on the comparison between digital elevation models (DEMs), derived from historical records, specifically maps (1975; scale 1:10,000) and photogrammetric surveys (1991 and 2003, scale 1:15,000). The results show a general glacier volume loss (–16.640 x 10 6 m 3 ( from 1975 to 2003; nevertheless if we focus on the two time sub-windows (i.e.: 1975-1991 and 1991-2003) opposite trends are found: in the period 1975-1991 the volume variation of the Miage Glacier was about +19.25×10 6 m 3 , in the period 1991-2003, on the other hand, a volume decrease of about –36.2×10 6 m 3 occurred. Analysis shows that volume changes were strongly influenced by the supraglacial debris coverage which on Miage glacier tongue modulates the magnitude and rates of buried ice ablation.