Various studies have shown that interannual variability of rainfall and river levels in the Amazon region can be, in part, attributed to the sea surface temperature (SST) variations in the tropical Pacific, manifested as the extremes of El Niño Southern Oscillation (ENSO), and to the meridional SST gradient in the tropical Atlantic, or to a combination of both (See reviews in [9-11] and references quoted therein). So far, observations do not show any unidirectional trend in rivers or rainfall, noticingexhibiting, instead, decadal variations linked to natural climate variability