Evolution of Water Resources in the “Bajo de Sarmiento” (Extraandean Patagonia): Natural and Anthropogenic Impacts.

Abstract

Water resources dynamics within a basin depend on natural variables (latitude, topography, and climatic variability) and the anthropic uses of those resources. Social perception on the basin environmental situation and the priority on resources use, define the degree of conservancy of water resources. Water resources conservancy is critical in the Argentinean Patagonia, where the arid conditions prevail since the early Holocene until the present. On this work, it is studied the dynamics of the hydrological resources (lakes and rivers) within the &ldquoBajo de Sarmiento&rdquo, located in the center of Argentine&rsquos extra Andean Patagonia. The aim of this work is to understand whether the social perception regarding the priority use of water resources is leading to management that could increase the impact that naturally affects lakes and rivers in the area by climate variability. Thus, the hidrogeomorfology dynamics of the &ldquoBajo de Sarmiento&rdquo, derived from the combined impact of climate variability and human activity, from the Holocene to the present, was rebuilt. Geological Sheet 4569-IV Escalante, the SRTM digital terrain model (30m) and Land Sat (5-7-8) satellite images were analyzed to compare the regime of the main permanent channels described and represented in the literature and historical cartography of &ldquoBajo de Sarmiento&rdquo with their current regimes. The data obtained were compared with fieldwork observations. On the other hand, structured survey was made to social actors related with water uses in the basin, in order to analyze the social perception on resources. The results showed that while climate variability (in particular the arid conditions prevailing since the middle Holocene) has historically been the main factor affecting the dynamics of water bodies in the area, the development of various human activities (based on the perception of the resources that the inhabitants have) have increased these effects over the past 120 years. Thus the basin has changed from exoreic to endoreic and one of the lakes located within it has been close to disappeared in 2016.