The river systems of the Amazon basin are important for the emergence of the countries that make up the fabulous ecosystem. This work aimed to analyze the hydrology of the Amazon Basin by observing its fluctuations and the possible influence of El Niño and La Niña phenomena in river dynamics. Hydrological analysis was carried out in 13 river systems, involving the Solimoes / Amazonas system by detailing the conditions of two fluviometric stations per basin from the hydrological database of the National Water Agency (ANA 2020). Through the analyzes we see that hydrological regimes show heterogeneous behavior, monthly variability upstream and downstream (in most rivers of the southern margin), at interannual and decadal scales at the level of the three (3) regions (Septentrional, the western part and the southern hemisphere). The El Niño episodes causing the variation of the flows cause a considerable decrease in the flows in the majority of the river systems studied more especially those of the left margin (Trombetas, Negro, Branco and Uatuma). On the other hand, the events of La Niña cause an increase in flows and runoff and more noticeable in the left margin. We also notice a strange aspect in most of the rivers which under the influence of the change of the glaciers in the mountain ranges of Bolivia and Peru, hence the glacial melting increases the flow rates of the rivers during El Nino and decreases the flows due to the transition of the water of the rivers to the solid state under low temperature and high altitude during the Nina and counteracts the permanence time of the flow of river systems of the right margin and the central part of the Amazon basin. ENOS events differ from each other, and their actions have caused a great deal of loss and damage to the surrounding environment for several decades. So, this study contributes a lot to the production and popularization of academic knowledge, the physical and dynamic understanding of the Amazon basin, to the assessment of the actions of ENOS-type climatic phenomena of the main river systems. In addition, it makes recommendations for monitoring and early warning against possible effects of ENOS on the hydrological regime, in river planicia and generally on the living conditions of the inhabitants of the Amazon basin.
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