Estimativas de Precipitação através das ocorrências de raios na bacia do rio Tocantins (RAINFALL ESTIMATES THROUGH THE LIGHTNING OCCURRENCES WITHIN THE TOCANTINS RIVER BASIN)
DOI:
https://doi.org/10.5935/1984-2295.20160069Keywords:
Amazônia. Raios.Precipitação. Bacias HidrográficasAbstract
O objetivo desse estudo foi estimar a precipitação media quinzenal na bacia do Rio Tocantins a partir de dados observados simultaneamente de ocorrência de raios, incidentes em área a montante da represa da Hidroelétrica de Tucuruí. Em geral, a relação entre essas variáveis não é linear e pode variar com o clima regional. Como a Amazônia já é razoavelmente coberta por redes de monitoramento continuo das ocorrências de raios, esse estudo pode contribuir para corrigir deficiências na obtenção de dados de precipitação, por outros meios de observação, nessa Região. As estimativas poderão subsidiar modelos numéricos para previsão de secas, enchentes e nível de água nas represas. Foram utilizados dados de raios coletados pela rede STARNET no período de setembro 2008 a setembro de 2010 e dados de chuva disponibilizados por vários sistemas de observação de superfície. Os resultados das análises desses dois anos mostraram que as médias quinzenais de ocorrências de raios e chuvas têm um comportamento sazonal semelhante, influenciado pelas oscilações de sistemas de grande escala como a ZCIT e ZCAS, e outros sistemas em meso escala. Correlações entre as variáveis foram apresentadas. Análises da relação entre cota de rios e raios indicaram que para períodos curtos houve boa correlação entre essas variáveis. Portanto o método desenvolvido nesse trabalho pode ser estendido satisfatoriamente e a baixo custo para suprir deficiências das redes de observações pluviométricas ou hidrológicas em outras bacias hidrográficas e/ou áreas de características fisiográficas distintas e de grande interesse socioeconômico na Amazônia.
A B S T R A C T
The main objective of this study was to estimate the biweekly average precipitation within the Tocantins River basin, using simultaneous data from lightning occurrences over an area up river from the Tucurui hydroelectric power dam. In general, the relation between these variables is not linear and may vary according to the regional climate. Considering that the Amazon Region is now reasonably covered by continuous monitoring lightning detection networks, this study will contribute to correct precipitation data collection deficiencies, by other means, in this Region. These estimates may subsidize numerical models to forecast droughts, floods and the water level at the reservoirs. Lightning events data collected by the STARNET system between September 2008 and September 2010 were processed, as well as, rainfall data from the available surface observation systems. The results from the analysis for this two years period showed that, both the biweekly averages of the lightning occurrences and rainfall have similar seasonal behaviors, influenced by large scale systems oscillations such as the ITCZ and SACZ, and meso scale systems. The correlations between these variables were presented in the work. Analysis of the river levels versus lightning numbers over short periods showed a good correlation between these variables. Therefore, the developed methodology for this work can be extended satisfactorily and at low cost, to remedy deficiencies of pluviometric and hydrologic observation networks, in other hydrographic basins and/or areas of distinct physiographic characteristics and great socio economic interest in the Amazon Region.
Keywords : Amazon Region. Lightning. Rainfall. Hydrographic Basins
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Copyright (c) 2016 Marcela Machado Pompeu, José Ricardo Santos de Souza, Wanda Maria do Nascimento Ribeiro
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