Variabilidade intrasazonal da vazão afluente nos principais reservatórios brasileiros

Abstract

One of the great concerns of the scientific community in the last decade concerns climate change and its consequences for humanity. The Brazilian hydric planning has faced constant challenges to guarantee supply and energy. In the various regions of the country, serious water shortages have been observed in recent years, due to the scarcity of rainfall, which has become more frequent and intense over the years. Due to its vast territorial extension and topographic complexity, Brazil has different precipitation regimes. Therefore, the study of changes in hydro-meteorological data time series is of extreme importance for the management of water resources. In this context, an analysis of the variability of the historical series of inflowing water flows of the main reservoirs in the country is fundamental for the understanding of the processes involved in drought episodes. It is known that the variability of the flow in these reservoirs is closely related to the rainfall regime of each region, which in turn is influenced by climatic variability. Among the climatic variability stands out the Madden-Julian Oscillation (MJO) or 30-60-day Oscillation, which is a mode of intraseasonal climate variability that plays a key role in precipitation over much of South America. Based on this theme, the present work aims to analyze, quantify and predict the influence of MJO on precipitation and consequent hydro-energy variability in Brazil. In this way, we sought to determine what is the contribution of this oscillation to the variability of tributary flows, in the period from 1990 to 2015, data obtained through the National Water Agency (ANA), in order to contribute substantially to the improvement of hydroclimatic forecasts. After the identification of the extemos events of the historical series (positive and negative anomalies of affluent flow) the following analyses were carried out through the method of Wavelets, with the objective of identifying the intensity and the temporal scale of the most expressive phenomena acting in each reservoir of this study. Then a filter was applied on the Wavelets in order to highlight the intraseasonal scale (MJO) and smooth the interannual scale to identify what is the contribution of this phenomenon for each of the regions studied. Finally, in possession of these results, a survey was carried out of the years in which the extreme of positive and negative intraseasonal anomalies of influent inflow occurred and through a comparison with the predominant phase of the OMJ for these same years, ir was verified that there is a association between phase 1 of the oscillation with extremes of positive intraseasonal anomalies and phase 5 with extremes of negatives intraseasonal inflow anomalies. In the last stage of this study, precipitation maps were generated with data from the BAM (Brazilian Global Atmospheric Model) focusing on the SE region. The results found show that the model satisfactorily representes the precipitation during the studie of MJO phases.