NGDIR News Section-- Researchers in the College of Arts and Sciences are closer to understanding how the loss of glaciers in the Cordillera Blanca of Peru is affecting water resources in a region responding to global climate change.
Laura Lautz G'05, associate professor of Earth sciences, is part of a multinational, interdisciplinary research team doing fieldwork in the northern Peruvian Andes. She and other researchers from A&S have been studying the groundwater hydrology of proglacial valleys -- areas formed by glacier recession -- in the ice-capped mountains, home to the world's highest density of tropical glaciers.
Their findings are part of a major article in Hydrological Processes (John Wiley & Sons, 2016), co-authored by scientists and engineers from McGill University and Ecole de Technologie Superieur, both in Montreal; The Ohio State University (OSU); and the French Research Institute for Development in Marseille.
The Andes contain 99 percent of the world's tropical glaciers -- slow-moving rivers of ice whose high elevations are virtually unaffected by balmy tropical temperatures. Such glaciers, however, are vulnerable to climate change. One study posits that, since the 1970s, Peruvian glaciers have lost nearly half of their surface area.
Given the density of glaciers in the Cordillera Blanca, communities downstream rely on groundwater discharge and glacier meltwater for their water supply during the dry winter months (i.e., May-September). Runoff from proglacial streams also supports small-farm and commercial agriculture, hydroelectric power generation and transnational mining operations.
Whereas meltwater comes from the melting of ice and snow, groundwater is the result of precipitation that soaks into Earth's surface; is transported underground and then returns to lakes, marshes and streams.
Lautz estimates that approximately half the discharge in the Cordillera Blanca's proglacial streams comes from groundwater.
What is not understood -- and is the thrust of her research -- is the spatial distribution of the groundwater discharge. Using a model called HFLUX, Lautz and her team, including postdoctoral research associate Ryan Gordon G'13, Earth scientist AnneMarie Glose G'13 and Ph.D. candidate Robin Glas G'18, have created an energy balance model of a stretch of river in Peru's Huascaran National Park.
Lautz's team found that 29 percent of the stream discharge at the reach outlet came from groundwater. Moreover, dye tracing revealed that 49 percent of the stream water exchanged with subsurface water.
Annual trips to the Cordillera Blanca are standard for Lautz's research group. Because of the high altitude (upwards of 13,000 feet) and lack of oxygen, she and her team travel lightly -- mostly by foot and pack-animal -- and work for a week at a time.