Eventos hidrológicos extremos na calha do Médio e Baixo Amazonas

Abstract

The hydrological extreme events have a direct link with the effects of rainfall on a particular river basin. On top of the context "Amazon Basin", actions generated by the inevitable action of natural phenomena among which stand out the oceanic forcings such as El Niño, La Niña and Atlantic dipole that act in order to modify the pattern of atmospheric circulation and consequently the rainfall pattern on a river basin district, entail not only in different river height gaps, above all, the social impacts reflected on communities residents in the margins and surroundings of the rivers are the major concern surrounding the global scenario. On Amazon there are reports two types of natural disasters, the droughts and floods of cities. In this way this research discusses statistically (through the technique of quantis) the fluviometric quota values that go beyond normalcy (central tendency) in the middle and lower Amazon channel in 31 years of data (1982 to 2012). The research also evaluates the social impacts associated with occurrences of droughts and floods and as an indicator for the analysis of such impacts, it was adopted the registers the number of homeless families. To achieve the goals, it was held a documentary research on: State Civil Defense Coordination of Ceará (CEDEC), data on pluvial dimensions were found in the database of the National Agency Water (ANA), the data of occurrences of El Niño/La Niña and Atlantic dipole obtained in the National Oceanic and Atmospheric Administration (NOAA), and Climate Prediction Center (CPC). The results show that the surrounding hydrological regime along the channel of the middle and lower Amazon reaches maximum peaks in the stations of Óbidos, Manaus, Parintins, Santarém and Oriximiná in the months of May and June. While for localities of Borba and Porto de Moz this regime is anticipated and is between April and may. The results also show that for the period of 31 years of study, the number of occurrences of floods was in greater quantity than droughts. The number of people stricken by events of drought and flood show that the hydrological extreme events are recurring in the middle and lower Amazon, and represent an indicator of reality of the structural conditions that each location features.