Dinâmica de inundação das planícies fluviais do Rio Xingu, na região do complexo hidrelétrico de Belo Monte - Altamira -PA
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Data
2017-08-21
Autores
Oliveira, Rita Denize de
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Universidade Estadual Paulista (Unesp)
Resumo
O Rio Xingu é afluente da margem direita da bacia hidrográfica do Rio Amazonas drena importantes cidades como Altamira, localizada a montante da Usina Hidreletríca de Belo Monte onde foi desenvolvida a pesquisa. A problemática que cerca a construção do empreendimento aponta para possíveis mudanças no regime hidrológico do Rio Xingu e, perdas de áreas de planícies fluviais na área residencial na área urbana. Esta pesquisa teve por objetivo caracterizar o comportamento hidrológico, averiguar as possíveis relações entre o regime hidrológico do rio Xingu e de afluentes de menor expressão de sub-bacias que drenam a cidade de Altamira (montante da barragem) durante episódios de enchentes. Teoricamente, as inundações foram analisadas como um sistema aberto dinâmico não linear. Metodologicamente, para entendimento do Regime Hidrológico foram analisados a evolução urbana de Altamira, os dados fluviométricos (vazão e cota) obtidos de postos da ANA da estação 18850000 – Altamira no período de 1971-2014, em que se avaliaram componentes do regime de fluxo relacionados aos processos ecológicos em ecossistemas fluviais e gestão dos recursos hídricos: a magnitude do fluxo, a duração, a periodicidade e freqüência (RICHTER et al., 1997; POFF et al., 1997). Seguido de um levantamento histórico das inundações, análise morfométrica das sub – bacias dos igarapés Ambé, Altamira e Panelas. A analise da serie das vazões máximas do Rio Xingu permitiu identificar possíveis datas de inundações que se concentram nos meses de março e abril. O primeiro período (1º - 1971-1986) registrou as maiores inundações que atinge a área urbana, relacionadas a eventos de La Niña como 1974 e 1985, que podem ser apoiados pelos registros históricos. O segundo período (1987-2002) apresentou menores ocorrências de inundações sendo marcado pelo predomínio de por eventos de El Niño, e o terceiro período; (3º 2003 a 2014) em que se observa que as inundações tornaram-se mais freqüentes, em virtude de eventos extremos relacionados a influencia de anomalias de Temperatura no Oceano Atlântico, alterações referentes ao uso do solo, culminando com o primeiro registro de inundação rapidas. A expansão da área urbana de Altamira alterou de ecossistemas fluviais importantes como as lagoas marginais, e que apresentam elevada conectividade com Rio Xingu e a Terra Firme. Após a construção da Usina Hidrelétrica de Belo Monte elevação a área urbana identificou-se cinco níveis de estabilidade em função da contaminação do lençol freático, elevação do nível do lençol, subsidência de terreno, afloramento de nascentes e freqüência de alagamentos.
The Xingu River is a tributary of the right bank of the Amazon River basin draining important cities such as Altamira, located upstream of the Belo Monte Hydropower Plant where the research was developed. The problems surrounding the construction of the project point to possible changes in the hydrological regime of the Xingu River and losses of fluvial plains in the residential area in the urban area. The objective of this research was to characterize the hydrological behavior, to investigate the possible relations between the hydrological regime of the Xingu River and the smaller sub-basin tributaries that drain the city of Altamira (amount of the dam) during flood episodes. Theoretically, the floods were analyzed as a dynamic nonlinear open system. In order to understand the Hydrological Regime, the urban evolution of Altamira was analyzed, the fluviometric data (flow and elevation) obtained from ANA stations of station 18850000 - Altamira in the period 1971-2014, in which components of the related flow regime To the ecological processes in fluvial ecosystems and water resources management: the magnitude of the flow, the duration, the periodicity and frequency (RICHTER et al., 1997; POFF et al., 1997). Following a historical survey of the floods, morphometric analysis of the sub - basins of the Ambé, Altamira and Panelas streams. The analysis of the series of maximum flows of the Xingu River allowed identifying possible dates of floods that are concentrated in the months of March and April. The first period (1 - 1971-1986) recorded the largest floods in the urban area, related to La Niña events such as 1974 and 1985, which can be supported by historical records. The second period (1987-2002) presented smaller occurrences of floods being marked by the predominance of El Niño events, and the third period; (3º 2003 to 2014) in which it is observed that floods became more frequent, due to extreme events related to influence of temperature anomalies in the Atlantic Ocean, changes in land use, culminating with the first record of rapid flooding. The expansion of the urban area of Altamira altered important river ecosystems such as the marginal lagoons, which have high connectivity with the Xingu River and Terra Firme. After the construction of the Belo Monte Hydroelectric Power Plant, the urban area was identified five levels of stability due to the contamination of the water table, elevation of the level of the sheet, subsidence of terrain, outcropping of springs and frequency of flooding.
The Xingu River is a tributary of the right bank of the Amazon River basin draining important cities such as Altamira, located upstream of the Belo Monte Hydropower Plant where the research was developed. The problems surrounding the construction of the project point to possible changes in the hydrological regime of the Xingu River and losses of fluvial plains in the residential area in the urban area. The objective of this research was to characterize the hydrological behavior, to investigate the possible relations between the hydrological regime of the Xingu River and the smaller sub-basin tributaries that drain the city of Altamira (amount of the dam) during flood episodes. Theoretically, the floods were analyzed as a dynamic nonlinear open system. In order to understand the Hydrological Regime, the urban evolution of Altamira was analyzed, the fluviometric data (flow and elevation) obtained from ANA stations of station 18850000 - Altamira in the period 1971-2014, in which components of the related flow regime To the ecological processes in fluvial ecosystems and water resources management: the magnitude of the flow, the duration, the periodicity and frequency (RICHTER et al., 1997; POFF et al., 1997). Following a historical survey of the floods, morphometric analysis of the sub - basins of the Ambé, Altamira and Panelas streams. The analysis of the series of maximum flows of the Xingu River allowed identifying possible dates of floods that are concentrated in the months of March and April. The first period (1 - 1971-1986) recorded the largest floods in the urban area, related to La Niña events such as 1974 and 1985, which can be supported by historical records. The second period (1987-2002) presented smaller occurrences of floods being marked by the predominance of El Niño events, and the third period; (3º 2003 to 2014) in which it is observed that floods became more frequent, due to extreme events related to influence of temperature anomalies in the Atlantic Ocean, changes in land use, culminating with the first record of rapid flooding. The expansion of the urban area of Altamira altered important river ecosystems such as the marginal lagoons, which have high connectivity with the Xingu River and Terra Firme. After the construction of the Belo Monte Hydroelectric Power Plant, the urban area was identified five levels of stability due to the contamination of the water table, elevation of the level of the sheet, subsidence of terrain, outcropping of springs and frequency of flooding.
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Palavras-chave
Regime hidrológico, Planícies fluviais, Usina Hidrelétrica de Belo Monte, Conectividade, Rio Xingu, Hydrological regime, River plains, Belo Monte Hydroelectric Plant, Connectivity