The Andean Glacier and Water Atlas

Glaciers play an important role in the hydrology of the Andes, especially in arid or semiarid regions. With their ability to store water during cooler periods and release it as meltwater during the dry season, they bridge the arid periods and act as an important buffer for human settlements and natural ecosystems (Buytaert et al., 2017). The decrease of glacier mass negatively affects a glacier’s ability to act as a store for water resources. As described earlier, in the short-term, the accelerated melt rate brings a surge in the melt runoff, often referred to as peak water, which could create unsustainable levels of water dependency among communities and people. In the long-term, after the initial surge ceases, there will be a decrease in the amount of streamflow. While the accelerated melting of glaciers in the Andean region is well understood and reported, the consequences to hydrological processes and human uses and activities are less clear and unequivocal. The consequences can be severe, as the decreasing amount of streamflow exacerbates seasonal variability and people´s vulnerability to extreme weather and climate change. The extreme drought in Bolivia in 2016–2017 is such an example, in which it caused the country to call out emergency status as reservoirs dried out and water needed to be rationed (Perez et al., 2017). Another example is the ‘mega-drought’ between 2010–2015 in central Chile, where rainfall was below average and caused severe water shortages in central Chile and western Argentina (Garreaud et al., 2017). Accelerated glacier melt

Glacier lake outburst flooding (GLOFs) The accelerated snow and glacier melt increase the formation of glacial lakes. In many cases, the lakes have limited moraine dam integrity, which could lead to dam failure over time, often causing glacier lake outburst flooding (GLOFs). The glacier lake outburst can trigger floods, and alter the water flow course, as well as altering the water quality due to high sediment loading. As such, GLOFs represent major hazards for people and communities living in the valleys in proximity to glacial lakes. There are many examples of the potentially severe impacts of GLOFs, such the threat to human life and the possible damage to infrastructure, including housing, roads and highways, and water supply systems. In 1941 a GLOF in Lake Palcacocha in Peru caused the death of 5,000 people. In 2010, parts of the Peruvian city of Carhuaz were destroyed by a large GLOF caused by Lake 513 (Carey et al., 2012). In 2008 and 2009, five major floods from glaciers occurred in Chilean Rio Colonia (IAI, 2010), a little GLOF occurred at Chimborazo (Glacier #13) in Ecuador on December 2016.

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