Navegando por Assunto "Secas - Amazônia"

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Acesso aberto (Open Access)
Contribuições das sub-bacias para vazão do rio Amazonas e riscos socioambientais associados a eventos hidrológicos extremos
(Universidade Federal do Pará, 2016-07-01) COUTINHO, Eliane de Castro; LIMA, Aline Maria Meiguins de; http://lattes.cnpq.br/6572852379381594; ROCHA, Edson José Paulino da; http://lattes.cnpq.br/2313369423727020
The Amazon Basin is constantly affected by episodes of drought and floods during phenomena such as El Niño and La Niña, in addition to Multidecadal Atlantic Oscillation, Pacific Decadal Oscillation, the Intertropical Convergence Zone and the South Atlantic Convergence Zone. These extremes precipitation cause severe changes in the flow and precipitation of the rivers of several sub -basins in temporal and spatial scale. In the Pacific Ocean the phenomena of El Niño and La Niña are the main mechanisms of interannual and decadal oscillations, causing extreme hydrometeorological in the Amazon, both temporal and spatial scale. Spatial variations of hydrological regimes of the Amazon tributaries show that during the occurrence of seasonal peak flows in the left margin of the tributaries are offset by the decrease of flow of the tributaries of the right bank . Thus, the length of the left bank of rainfall is behind two months of the rainy season on the right bank. In addition to this variation the hydrometeorological extremes cause environmental, social and economic to the population, especially those with high vulnerability. The objective of this work is to study the hydrometeorological regime and the water balance of the Amazon Basin, determining its role in the return flow of the Amazon River to the Atlantic Ocean, as well as the socioeconomic and environmental risks associated with hydrometeorological events. For this we used monthly and annual data flow and precipitation in the period 1982-2012 (31 years) along the main Amazon river channel and 8 sub-basins, as well as an analysis of social and economic risks was made in municipalities of the Amazon basin. The precipitation trends over the study period were negative, in the southwestern part (Purus) and central (Madeira) of the Amazon Basin, and positive on the east side (Tapajós and Xingu). The Amazon Southwest sub-basins were negative extremes and extreme events (El Niño) throughout the study period. It is concluded that the flow in the channel of the main river in the Amazon basin depends on variations in the tributaries of the right and left bank. Seasonality is influenced in the dry season by the tributaries of the right bank , for matching the negative trend over the period studied , and the rainy season is influenced by the tributaries of the left bank . All these fluviometric variabilities cause risks to the population. Thus, it can be said that the socioeconomic and environmental risk is more dangerous during flood events, particularly in states with smaller spatial scale (Rondônia and Roraima) , and greater vulnerability occurs in states with higher spatial scale (Pará and Amazonas) this can be explained by the lack of public policy.
Acesso aberto (Open Access)
Modelagem hidrológica para extremos de inundações e secas para o município de Boa Vista em Roraima.
(Universidade Federal do Pará, 2018-09-24) CARVALHO, Adriana Alves de; ROCHA, Edson José Paulino da; http://lattes.cnpq.br/2313369423727020
The present research is based on statistical methods applied as an analysis tool in the study of the interaction between ocean and atmosphere in the up and down behavior of the Branco river in Boa Vista. Individual associations for years of floods and droughts conditioned to the oceanic component, evaluated by Sea Surface Temperature (SST) in the monitored areas of Niño 1 + 2, Niño 3.4, Niño 3, Niño 4 and North Atlantic Tropical (ATN); (PD) and Tahiti (PT) regions were evaluated through the acquisition of monthly climatic data from the Climate Prediction Center in 1982-2016. These associations aimed to investigate if these areas present favorable indicatives for extreme years of floods and droughts. Significant correlations were found above 0.5 in most flood and drought events in the following areas: Niño 1 + 2, Tropical Atlantic North, both with a lag time of 4 months, and the Darwin and Tahiti regions, but the effects of these variables to change the fluviometric regime of the White River in Boa Vista is 6 months. This information obtained through the calculation of the correlation coefficient (r) allowed the use of the Least Squares Method to model the prediction of the variability of flood and drought events induced by the seasonality of the Branco river. The long-term trends and numerical oscillations reproduced by the model for both scenarios were compared with the level measurements for the period 2011-2016. The results showed good performance of the model, with a percentage error of 30% for the prediction of drought events and 34% for those of floods, thus indicating that the selected input components exert a great contribution in the predictability of hydrological extremes in Boa Vista. Given this, it is suggested that this study can become operational in the monitoring centers of the state of Roraima, as a tool to support planning actions in the period of floods and droughts.