MOREIRAS Stella Maris
congresos y reuniones científicas
First-order characterization of threatening lakes in the Central Andes of Argentina (31-36º S).
Congreso; Annual Meeting. British Society of Geomorphology (virtual); 2021
Lakes are a distinctive element on mountain landscapes being a priceless resource for both society and nature. They constitute freshwater reserves and tourist attractions allowing the development of natural high-altitude ecosystems. On the other hand, they can also pose a risk to downstream communities in case of outburst floods. In the context of global warming related to the imminent Climate Change, an increase in the number, size, and volume of these lakes is expected due to glacier melting. The aim of this study is to inventory and characterize existing lakes in the Central Andes of Argentina (31º ? 36º S) to understand the potential risk associated with their catastrophic drainage. For this purpose, we use Landsat satellite images from the year 2020 in order to identify lakes by means of the Normalised Difference Water Index (NDWI) and visual interpretation, and were digitized with a manual approach. Lakes were classified into seven main types according to the damming processes or associated landforms, and statistical analysis of the main lakes´ attributes was carried out in order to characterize their spatial distribution. Our results reveal 642 lakes which account for a total volume estimated at 1,551.7 hm3. Different types and quantities of lakes prevail in each region according to the geomorphology and lithology. Thus, moraine-dammed lakes and landslide-dammed lakes are more important in terms of volume contribution between 31º - 32º S; while at ~32.5º to 34º S small glacial lakes linked to thermokarst facies over debris-covered glaciers prevail. At ~34º S, the Laguna del Diamante volcanic lake represents more than four-fifths of the total water volume estimated for the region; while between 34º and 36º S water bodies seem to be forced by geology, showing a wider diversity of lake types and greater volumes. Typically, glacial, moraine, and bedrock-dammed lakes are located in the periglacial and glacial environment (~ 3,730 m asl) while karstic and landslide-dammed lakes are set at the bottom of the valleys at lower altitudes between 3,200 to 2,600 m asl. This inventory provides the first step for an outburst flood hazard assessment in the region and highlights the importance of considering all types of lakes in terms of water resources in the Semiarid Central Andes of Argentina.