Recent rainfall and runoff variability in central Argentina

PASQUINI, A., K. LECOMTE, E. PIOVANO AND P. J. DEPETRIS

QUATERNARY INTERNATIONAL

Año: 2006 p. 127 - 139

1040-6182

Laguna Mar Chiquita, a closed, shallow, hypersaline lake in central Argentina (30–311S, 62–631W), is a sensitive marker of high- and low-frequency changes in regional hydrology and, therefore, of climatic changes at middle latitudes in southeastern South America. Its drainage basin and neighboring areas, including the Sierras Pampeanas de Co´ rdoba, and Sierra del Aconquija (27–331S, 62–661W), are under the influence of diverse climate drivers that determine a complex behavior in rainfall and runoff dynamics. Statistical (Mann–Kendall and seasonal Kendall trend tests) and spectral analyses (Fourier and wavelet transform) of the available data show that: (a) there is significant evidence that rainfall has increased in the region since the 2nd half of the 20th century; (b) concurrently, runoff has also increased, particularly in the northern tributaries (north of 311S) of Mar Chiquita; (c) northern rainfall and discharge records mostly exhibit an apparent near-decadal (also near-bidecadal in runoff) climatic signature; and d) the ENSO influence on rainfall appears faint but discernible in the southern (south of 311S) portion30–311S, 62–631W), is a sensitive marker of high- and low-frequency changes in regional hydrology and, therefore, of climatic changes at middle latitudes in southeastern South America. Its drainage basin and neighboring areas, including the Sierras Pampeanas de Co´ rdoba, and Sierra del Aconquija (27–331S, 62–661W), are under the influence of diverse climate drivers that determine a complex behavior in rainfall and runoff dynamics. Statistical (Mann–Kendall and seasonal Kendall trend tests) and spectral analyses (Fourier and wavelet transform) of the available data show that: (a) there is significant evidence that rainfall has increased in the region since the 2nd half of the 20th century; (b) concurrently, runoff has also increased, particularly in the northern tributaries (north of 311S) of Mar Chiquita; (c) northern rainfall and discharge records mostly exhibit an apparent near-decadal (also near-bidecadal in runoff) climatic signature; and d) the ENSO influence on rainfall appears faint but discernible in the southern (south of 311S) portion