May 29, 2010
Artesonraju Glacier is a 3.3 km long glacier in the Cordillera Blanca of Peru drains west from Nevado Artesonraju. The glacier feeds both Lake Artesonraju, a new lake that formed after 1930 and Lago Paron. The two lakes are dammed by glacier moraines and together have posed a hazard of a glacier dammed lake outburst. In 1951 an outburst of water and alluvium traveled from the upper Artesonraju Lake into Lago Paron, raising the water level in Paron causing downstream flooding and concern about the strength of its moraine dam.
There are numerous moraine dammed lakes in Peru, the dams are just comprised of gravel, sand and clay dumped by the glacier. High water levels caused by upstream floods, avalanches or landslides can cause failure of these moraine dams and down stream flood damage prompted the Peruvian government to develop a strategy to address the problem. They began in the by building tunnels, concrete pipes, through the moraine to allow drainage to a safe level, they then rebuilt the moraine over the drainage system and strengthened it. Since development these systems have worked preventing serious flood issues from the lakes. At Lago Paron a hydropower project has been built that is fed by the tunnel drainage system and Lago Paron has been partially drained to service the hydropower facilities needs. The hydropower faility is owned by Egenor, owned largely by Duke Energy. The lake level has declined substantially by 2003 as the trimline indicates in the image above. This had led to a battle over water resources with local farmers. This Artesonraju Glacier that is the principal feeder to the two lakes retreated 1140 meters from 1932-1987 and by 2004 had retreated another 200 meters. From 2003 to 2013 the glacier continued to retreat and the terminus to narrow. An expanding lake at the terminus is evident in the Google Earth images of 2003 and 2012, pink arrow. A melt pond has also drained at the yellow arrow as the glacier thinned. In the 2013 Landsat image the terminus has further narrowed.
2003 Google Earth image
This is 30% of its length gone in the last 75 years.The lower section of the glacier is flat, uncrevassed and is continuing to thin and melt. The upper reaches of the glacier are heavily crevassed indicating continued vigorous flow fed by healthy accumulation on the flanks of Nevado Artesonraju and Nevado Piramide. The equilibrium line of this glacier is at 5150 m, investigations by the Tropical Glaciology Group, Innsbruck, Austria and Hydrology Resources and Glaciology group in Huarez, Peru. In 2005, the surface on many parts of the flat tongue showed that sublimation is important to the mass balance when short wave radiation is limited, and short wave radiation dominates melting during the day.
A new book by Mark Carey, In the Shadow of Melting Glaciers, examines the history of the impact of these glaciers on Andes towns in the Cordillera Blanca.