Glacial and Periglacial Geomorphological Study Associated with the Evolution of Rock Glaciers in the High Basin of the Río Cochiguás, Coquimbo, Chile

In the high mountain range of the Elqui Province, Chile, a landscape dominated by glacial and periglacial processes is recognizable. Glaciers have been identified as potential water reservoirs, although their dynamics and hydrological contribution have not been fully understood. Therefore, the study of these landforms becomes relevant to generate sustainable policies for the management of these potential water resources. Here, the volumetric variation of two rock glaciers in the basin of the Río Cochiguás for the period 1956–2018 is quantified, in order to establish the influence of geomorphological evolution, climatic variations and their possible hydrological implications to the watershed. A geomorphological map of the area was made. Topographic data were taken using differential GPS and a characterization of their detrital cover was developed. With this, it was possible to compare the volumes of the rock glaciers over time by comparing the current topography with surfaces reconstructed from aerial photographs of 1956 and 2000 of the same area. Glacial and periglacial landforms, cryogenic features among other geomorphic features were identified through the mapping. Some glacial landforms exhibit evident cryogenic features such as selection by freezing, slight grooves and superficial ridges and furrows, and a steep lateral slope composed of finer material. Valley-bottom rock glaciers, protalus lobes, gelifluxion slopes and avalanche deposits were also identified. The debris cover of the rock glaciers was conditioned by the high degree of weathering of the source outcrops. In addition, the angle of the frontal slope of these landforms is greater than the angle of repose, and they exhibit some surface features as ridges and furrows. These features indicate that these bodies are active, and that physical weathering processes play an important role in their dynamics. The comparison of rock glacier volumes indicated considerable changes, given the decrease in precipitation and the increase in temperature in recent years in the area, which would have a direct impact on freshwater reserves for the region.