ABSTRACT: Until the mid 1970s a negative trend in the river flow values in the Argentinean provinces of San Juan and Mendoza (Cuyo region) was observed. The prevailing critical conditions and their economic and social impacts provide a basis for the characterization of an adverse climate change scenario for the region. The causes of the early 1970s scenario were assessed in this study in order to determine whether or not it could be related to global warming conditions. River flows are dependent on winter precipitation and on accumulated snow on the Andes cordillera. The lowest negative river flow value observed can be explained by the behaviour of the Southern Oscillation Index (SOI) and other macroclimatic parameters, such as sea-surface temperatures (SSTs) of the Atlantic and Pacific oceans. It was observed that the SOI is the parameter most strongly correlated with river flows. The highest correlation was found for the 2.4- and 4.8-yr frequencies and the low 43-yr frequency. Consequently, the low river flow values observed during the early 1970s are considered to be related to a low-frequency minimum of the El Niño-Southern Oscillation (ENSO), as well as to the behaviour of sea-surface temperature close to the coast of Chile. Both factors are associated with a minimum hemispheric temperature value. It is concluded that the 1960-70 drought in the oases of the cordillera was not linked to a warm period. Therefore it is not appropriate, at least for the time being, to state that the oases will experience drought conditions under a global warming scenario with temperature increases of a few degrees.

KEY WORDS: Climate change · Southern Oscillation · Sea-surface temperatures · Flow anomalies · Rivers of the Cuyo region

Published in CR Vol. 9, No. 1-2 (1997) on December 29
ISSN: 0936-577X. Copyright © Inter-Research, Oldendorf/Luhe, 1997