The interannual Climate Variability and the Streamflows in Paraná river, Southeastern South America

uth America. The relationship is explored between ENSO phenomenon and streamflows in one major river of southeastern South America (Paraná river). Every year during the period 1900-1997 is categorized as El Niño event (warm phase), Niña event (cold phase) or Normal year (no-Niño, no Niña), according to well-know criteria.

The analysis is carried out considering a composition of warm events years, cold events years and normal years. Based of this categorization, the 30-months, 24-months and 18-months composites of the streamflows are prepared for the three cases.

The composite analysis shows that the streamflows in the upper Paraná river basin tend to be above the average during the period October to February in warm events. During the period June to August in cold events, streamflows tend to be below the average.

This findings agree with previous works that show the associations between extremes in ENSO events and rainfalls and streamflows variability on southeastern S