MODELING THE DISTRIBUTION OF MOUNTAIN PERMAFROST IN THE CENTRAL ANDES, SAN JUAN, ARGENTINA

A five-year field program in the high-altitude Dry Andes has focused on identifying and mapping the distribution of buried ice to better understand its potential contribution to the regional groundwater budget. The surface velocities of several rock glaciers and protalus ramparts, measured using repeat GPS, LIDAR, and Structure from Motion (SfM) data, range from 1 and 7 cm year^-1and suggest the presence of buried ice. However, many features that are frequently associated with permafrost conditions, such as sorted nets and solifluction lobes, are stationary, with no subsurface ice, and are likely relicts of past colder climates. Statistical analyses of temperature data from 69 sensors installed in the shallow subsurface across the latitudinal and altitudinal range of the study domain are used to predict permafrost conditions via mean annual ground temperature (MAGT) and bottom temperature of winter snow (BTS) based models. Our data and resultant models indicate that: 1) insolation and elevation are the essential variables for predicting ice locations, and 2) buried ice is discontinuous and only found at higher and topographically steeper portions of the landscape, when not in rock glaciers and protalus ramparts. When our surface motion and temperature data are compared with geophysical data and shallow (1 to 2 m) excavations in our study areas, we find that buried ice is typically associated with areas of thick debris cover in rock glaciers and protalus ramparts. Discontinuous ice does occur at elevations above 3800 m as our models predict, but the shallow depth to bedrock restricts its presence in these terrains. In contrast to other regional studies in the Dry Andes, we find that buried ice likely plays a limited role in the annual water budget at our two study sites, a result corroborated by previous geochemical and hydrological results at our locales. Our results underscore the importance of completing thorough field, surveying, and climate-modeling studies not only to separate active and relict landforms in an area where permafrost is protected by law as a periglacial feature, but also to allow for the development and coexistence of sustainable mining operations and local communities.