Glaciers and rock glaciers' distribution at 28A° SL, Dry Andes of Argentina, and some considerations about their hydrological significance

The area studied includes a little-known portion on the Dry Andes of the San Juan Frontal Cordillera, Argentina, where the hydrological significance of glaciers and rock glaciers was earlier never studied. The surveyed sector includes Cerro El Potro (5,870 m ASL) and nearby mountain chains (28A degrees S). The predominant landforms in these areas were shaped in a periglacial environment superimposed on an earlier glacial landscape. These regions comprise abundant rock glaciers, a noteworthy rock glacier zone in the world, of which little is known in South America. This work employs geomorphological mapping to analyze the distribution of active rock glaciers in relation to altitude, aspect and slope using optical remote sensing techniques with GIS. Statistical estimation techniques were used based on a Digital Elevation Model (DEM) and aerial photos and Spot images interpretation. The specific density of rock glaciers' estimation in the surveyed area (Argentine border) is 1.56% with corresponds to 38 rock glaciers with an area of 5.86 km(2) and 0.12 km(3) of water equivalent. Furthermore, the analytical results show that elevations > 4,270 m ASL, a southeast-facing aspect, and slope between 2A degrees and 40A degrees favor the existence of rock glaciers, Finally, a comparison with glacier water equivalent, which covers an area of similar to 16 km(2) and 0.9 km(3) of water equivalent, shows that glaciers are the main stores of water at 28A degrees S (Cerro El Potro Glacier). However, the importance of rock glaciers as water reserves in this portion of Argentina should not be underestimated.