May 12, 2016

Vallelunga and Barbadorso Glacier Retreat, South Tyrol Italy

Posted by Mauri Pelto

vallelunga compare

Vallelunga (above) and Barbadorso di Dentro Glacier (below) retreat from 2003 (orange line) to 2015 yellow dots.  Blue arrows indicate flow path and pink arrow the junction of main two tributaries of Vallelunga Glacier.

Vallelunga Glacier and Barbadorso di Dentro Glacier are at the headwaters of the Vallelunga watershed which feeds the Reschensee.  Reschensee is a reservoir famous for the church tower that emerges above its surface.  This artificial lake was completed after World War II and is the reservoir for the 105 MW Glurns Hydroproject owned by Seledison.  These two glaciers are examined as part of the annual campaign of the Italian Glacier Committee.  The annual reports for 2011-2013 indicate a retreat of 78 m for Vallelunga and 60 m for Barbadorso.  Here we examine Google Earth images from 2003 and 2015 to indicate the change in a twelve year period.

In 2003 Vallelunga Glacier terminus was at an altitude of 2500 m.  The glacier is comprised of two tributaries that join at the pink arrow. The orange line is the 2003 terminus location. By 2015 the smaller western tributary has nearly separated from the main glacier.  the terminus has retreated 460 m in the 12 year period. Barbadorso Glacier terminated at 2690 m in 2003.  By 2015 the terminus has retreated 250 m and terminates 100 m higher in elevation at nearly 2700 m. On July 31, 2015 the snowline on the two glaciers is at 3100-3200 m with 6-8 weeks left in the melt season.  This indicates another year of negative mass balance that will continue to drive retreat.

These glaciers are just across the border from Gespatcherferner one of the fastest retreating Austrian Glacier’s in recent years. Carturan et al (2016) examining long term Italian glacier mass balance series note the 2004-2013 period as particularly negative.  They further observe that this is mainly due to increased ablation and that annual balance is becoming more closely correlated with accumulation season (October-May) temperature suggesting warmer winters extending melt season and leading to an increased ratio of winter rain events. The continued reduction in glacier area reduces late summer water flow to the reservoir, which will either cause reduced power output or the need for more storage early in summer (Pelto, 2014).

reschensee ge

Vallelunga watershed feeding Reschensee (R).  Vallelunga Glacier (V) and Barbadorso Glacier (B).

vallelunga 2015 tsl

July 31, 2015 Landsat indicating a high snowline, purple dots, with nearly half the summer to go.