Geografía UC

 

Cryosphere as a solid water storage system associates to different value concerns. This association is critical in water planning assessments and water security, especially in the context of mountain cryosphere at semi-arid regions like the dry Andes. For example, the Aconcagua basin has been officialy declared a water scarce region since 2008, considering upcoming snow deficits and surface warming, it is important to understand the current dynamic and future evolution of its hydrological components.

The current work assesses the potential role of frozen grounds (permafrost) at glacierized, high altitude headwater catchments in the Central Andes of Chile, 80 km NE from Santiago. The first task is to understand if there is permafrost and how it is distributed throughout the catchment, and secondly, if there are attestable signals which can be used as a proxy to understand subsurface dynamic and consequently storage and baseflow implications. The methods include analyzing water isotopes (stable and unstable), electrical resistivity survey, parameterizing the catchment in terms of hydraulic properties and the analysis of genetic sequences from water in groundwater springs.

Results show current ground ice present within the catchment at 3600m ASL, the lower boundary. And that about a 12% of the catchment above that boundary is under favorable permafrost conditions. The hydrogeological analysis delivered sub-decadal transit times for groundwater spring flows, also associated with cold microbial diversity signatures. The results imply a subsurface reservoir that gives a thawing input at least by April, and consequently show that within a permafrost affected catchment, permafrost should have a seasonal inputs to streamflow. This represents an issue for assessing hydric potentiality (value) as it currently may overlook reallocations from one cryosphere element (surface) to another (groundwater related) if the system supply capacity is not framed as a comprehensive, bounded unit.