Zongo Glacier Retreat, Bolivia 1994-2014.

Zongo Glacier, Bolivia extends 2.9 km down the south side of Huayna Potosi from 6000 m to 4900 m. Zongo Glacier is a small valley glacier located 30 km north-east of La Paz, and its runoff is directed to an important hydraulic power station which supplies La Paz. Note Laguna Milluni in foreground of the first image. The dam is visible as is the power station to the right and below the lake. The glacier has considerable snowcover on its upper section and crevassing. This indicates a persistent accumulation zone. In 1991 a glaciological research program was established on Zongo Glacier to monitor mass balance, understand its hydrology and energy balance. The long term director of this research Bernard Francou has been called the glacier guardian. The cumlative mass balance of the glacier from 1991-2013 has been -6.5 m water equivalent. The typical Alpine glaciers undergoes a long accumulation period in winter and a short ablation season in summer. The glaciers of the tropical Andes experience snow accumulation during the wet season, austral summer on their upper regions and maximum ablation during the same season low on the glacier. In the dry season winter there is a period of low ablation over the whole glacier. Mean annual air temperature at the long term snowline at 5250 m is -1.5 °C. Mean precipitation is about 0.9 m/year. zongo laguna
Google Earth image-Huayna Potosi and Zongo Glacier

Since 1991 the glacier has lost more than 7 m of thickness and has retreated significantly. The mass balance loss has been most pronounced during El Nino periods. La Nina’s are associated with positive or only slightly negative mass balance. Here we examine Landsat imagery and Google Earth imagery form 1994 to 2014.

In 1994 there is no lake at the terminus of the glacier, red arrow. By 2004 the Google Earth image indicates the glacier terminating along the northeast shore of the lake, a 90 m retreat in a decade. By 2008 the glacier no longer reaches the edge of the lake, but the front is still crevassed. In 2014 the glacier terminates 100 meters from the lake. Total retreat during the 20 year period is 220 m. The current terminus in 2014 is dirtier and less crevassed than in 2004, and less crevassed than in 2008. The lower 200 m of the glacier is thin, narrow and lacks active crevassing. This relatively stagnant area will melt away in the next decade.

Zongo Glacier continues to have an accumulation zone, a necessary essential for glacier survival, and unlike the nearby Chacaltaya Glacier which disappeared in 2009, it will exist for sometime. The Chacaltaya Glacier is a small glacier, like 80% of the glaciers in this region of the Cordillera Real, and its disappearance puts more pressure on the water resources provided by the larger remaining glaciers such as Zongo Glacier. Rabatel et al (2013) note the striking rise in the freezing levels in the region due both to higher temperatures and more convective activity that is a particular threat to glacier survival.

zongo ls 1994
1994 Landsat image

zongo 2004
2004 Google Earth image

zongo 2008
2008 Google earth image

zongo 2014
2014 Google Earth image

zongo ls 2014
2014 Landsat image

Nevado Cololo Glacier Retreat, Bolivia

Nevado Cololo is a glaciated mountain area in the Cordillera Apolobamba of northwest Bolivia. Here the focus is on a glacier draining west from the Nevado Cololo into the Rio Suches and then Lake Titicaca. The glaciers of the Apolobamba have lost 48% of their area from 1975-2006 (Hoffmann, 2012). Hoffmann and Weggenmann (2012) have observed both the extensive retreat, new lake formation, and the problem of glacier lake outbursts in this region, which is part of the Apolobamba Integrated Natural Management Area. The glacier that is our focus has developed a new lake at its terminus since 1988, the glacier begins at 5700 m and ends at 4930 m. cololo 2005. The red arrow in each image indicates the 1988 terminus position which was at the top of a bedrock cliff evident in all images. The yellow arrow is the 2012 terminus position at the base of a second cliff. By 2005 the glacier had pulled back from the cliff exposing a new lake that is 400 meters across. The glacier still ends in the lake. By 2012 last two images, the glacier has retreated several hundred meters from the shore of the lake and ends at the base of a cliff at 5000 m. The glacier should rapidly retreat to the top of this cliff. The retreat from 1988-2005 was 540 m, the retreat from 2005-2012 has been 280 m. The total retreat over 25 years is 820 m or 33 meters per year.

cololo 1988

cololo terminus

cololo 2011

cololo 2012The retreat of this glacier fits the pattern of other Bolivian Glaciers, such as the Zongo Glacieror Laramcota Glacier and tropical Andean glaciers in general (Rabatel et al, 2013).

Laramcota Glacier Retreat, Bolivia

Laramcota Glacier is in the Cordillera Tres Cruces of Bolivia. The glacier feeds into Laguna Laramcota and eventually the Rio Boopi, Rio Beni and finally the Amazon River. The glaciers of Bolivia have received much less scrutiny than those in Peru or Chile, but are quite numerous. Riberio et al (2005) noted a 32% loss of glacier area inn the Tres Cruces from 1972-1999 using satellite imagery. Melocik (2010) in a preliminary report using remote sensing noted a 40% loss in Tres Cruces glacier area from 1985 to 2005. This is a quite a substantial loss, and is likely a maximum loss as some of the area lost at higher elevation could have been non-glaciated snow covered area. Here we examine the changes in Laramcota Glacier using Landsat imagery from 1988 and 2011. The 2.6 km long glacier flows west from 5600 meters to a terminus at 5000 meters.laramcota ge In 1988 the glacier ends at a small lake one kilometer upstream of Laguna Laramcota, orange arrow. The glacier just to the east ends just 600 meters from the Laramcota, red arrow. The ridge separating the two glaciers at the purple arrow is quite narrow. By 2011 the glacier has retreated 300 meters from the lake, orange arrow. The glacier just to the east has retreated 200-300 m as well. The ridge separating the glaciers has expanded considerably in width, purple arrow. The overall loss in glacier from 1988-2011 is 10-15%. The retreat of this glacier fits the pattern of other Bolivian Glaciers, such as the Zongo Glacier or Nevada Cololo and tropical Andean glaciers in general (Rabatel et al, 2013). lamarcota 1988 laramcota 2011

Zongo Glacier retreat

Zongo Glacier, Bolivia extends 2.9 km down the south side of Huayna Potosi from 6000 m to 4900 m. Zongo Glacier is a small valley glacier located north-east of La Paz, and its runoff is directed to an important hydraulic power station which supplies La Paz. Note Laguna Zongo in foreground of the first image. The dam is visible as is the power station to the right and below the lake. The glacier has considerable snowcover on its upper section and crevassing. This indicates a persistent accumulation zone. In 1991 a glaciological research program (page 46) was established on Zongo Glacier to monitor mass balance, understand its hydrology and energy balance. The long term director of this research Bernard Francou has been called the glacier guardian. The typical Alpine glaciers undergoes a long accumulation period in winter and a short ablation season in summer. The glaciers of the tropical Andes experience snow accumulation during the wet season, austral summer on their upper regions and maximum ablation during the same season low on the glacier. In the dry season winter there is a period of low ablation over the whole glacier. Mean annual air temperature at the long term snowline at 5250 m is -1.5 °C. Mean precipitation is about 0.9 m/year.

Since 1991 the glacier has lost more than 5 m of thickness and has retreated significantly. The mass balance loss has been most pronounced during El Nino periods, thus 2009 should not be a good year for Zongo Glacier. La Nina’s are associated with positive or only slightly negative mass balance. The ongoing mass balance loss has led to retreat of 184 meters of this glacier from 1996-2005. A comparison of satellite images from 2004-2008 indicate a retreat of 70-75 meters, this is consistent with the reported retreat rate of 18 meters per year. The glacier has withdrawn from the new glacier lake formed from the ongoing glacier retreat in the 1990’s. The images below are focussed on the terminus in 2004 and in 2008, note the retreat from the lake shore.

Zongo Glacier continues to have an accumulation zone, a necessary essential for glacier survival, and unlike the nearby Chacaltaya Glacier which has disappeared in 2009, it will exist for sometime. The Chacaltaya Glacier is a small glacier, like 80% of the glaciers in this region of the Cordillera Real, and its disappearance puts more pressure on the water resources provided by the larger remaining glaciers such as Zongo Glacier.