El niño driven climate variability and drainage anomalies in Patagonian region Argentina

Abstract

Forecasting of interannual and seasonal variability of hydrological processes is very important when planification of water resources is involved.The hydrological cycle and the climate system are intimately linked, and the knowledge of the atmospheric general circulation disturbances allows the mentioned forecast. It is increasingly clear that hydrological variability can be interpreted in terms of large-scale climatic anomalies-such as those associated with El Niño/Souther Oscillation (ENSO), and that there are strong relationships between hydrological anomalies in different parts of the world. Environmental and human characteristics of Patagonian region also contribute to its vulnerability to changes in water availability. Important characteristics are large demand for water supply, extensive development in floodplains, vulnerable groundwater supplies, water-quality problems, dependence on rain fed agriculture, and extensive dependence on hydroelectricity. Regions where water is already scarce during part or along the whole year are especially vulnerable to the disruption of supply caused by such climatic variability as prolonged or intense droughts. This paper describes the relationship between ENSO and river discharges of several Patagonian basins. The period with the highest discharge was selected and the accumulated anomalies of the river discharges were used as hydrological variable. The indexes considered were the sea surface temperature (SST) in the Pacific Ocean as a function of El Niño3 (90°W-180 ° W; 5°N-5°S) on the Tropical Pacific Ocean, and the Multivariate ENSO Index (MEI). The results were evaluated with a simple linear regression model. They showed a relationship between ENSO (as function of SST) and annual discharges, while MEI index has no significant results.