A century of limnimetric shifts in central Argentina: floods, droughts and climate change linkages

LUCÍA GUERRA; EDUARDO LUIS PIOVANO; MATEO ANTONIO MARTINI

Zaragoza

Congreso; 5th PAGES Open Science Meeting; 2017

PAGES

Extreme hydro-climate changes recognized in southeastern South America (SESA) for the last 200 years have affected water resources and thus the ecosystems and human population depending on them. For instance, important precipitation increases were recorded between the 1970s and 2003 and between 2013 and the present in SESA (i.e. central and northeastern and central Argentina, Uruguay, Paraguay and southern Brazil). In contrast, severe droughts reducing water availability were documented through historical and paleoclimatic archives for early 19th century. In the Pampean Plains from central Argentina, rainfall conditions interplay with a flat terrain geomorphology, ruling the environmental response of the hydrological systems. Pampean lakes and wetlands are mostly closed systems, where vertical water interaction dominates the hydrological balance (i.e. rainfall and evaporation) and they are extremely sensitive to water balance changes. The Melincué Lake (33°S/61°W), situated in this geographical context, has suffered large surface variability with severe floods during wet climates affecting agriculture and grazing lands, roads and the Melincué town, followed by important lakesurface reductions during dry periods. In this contribution we present an analysis of the limnimetric shifts of Melincué Lake linked to the regional rainfall variability of the last 100 years, and compare both variables with historical and limnogeological records. Instrumental information provides direct data of the recent climatic variation setting the base of calibration of paleoclimatic proxies. Statistical analyses applied on the data indicate different periodicities of the hydroclimate variation. The lake-level oscillations show superposed signals, with a stronger variability associated to the Pacific Decadal Oscillation, with wetter periods registered as organic-rich sedimentary deposits. Understanding how the lake reacts to variable precipitation in the region will permit vulnerable societies dependent on the water resource to plan strategies for extreme drought or floods situations of future climate changes.