Vazão Mínima para Estuários: Um Estudo de Caso no Rio Paraguaçu/BA

Genz, Fernando; Lessa, Guilherme C.; Cirano, Mauro

doi:10.21168/rbrh.v13n3.p73-82

Cited by 18 publications

(19 citation statements)

References 8 publications

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“…The construction of dams to supply water is a common intervention in most rivers flowing through semi-arid areas that significantly impacts the physicochemical characteristics and circulation of estuaries by reducing their flow in the rainy season (GENZ et al, 2008) and maintaining a perennial flow during the dry season. The reduction of flow results in increased salinity intrusion and a decreased sediment load, increased residence time and changes in the dynamic maximum turbidity zone (REDDERING, 1988;SKLAR;BROWDER, 1998;ALBER, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…The reduction of flow results in increased salinity intrusion and a decreased sediment load, increased residence time and changes in the dynamic maximum turbidity zone (REDDERING, 1988;SKLAR;BROWDER, 1998;ALBER, 2002). However, the perennial flow can produce an increase in the average flow during the dry season, which may result in increased water-column stratification associated with the gravitational circulation and residual circulation displacing the estuary zone seaward (GENZ et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Intra-tidal variation of stratification in a semi-arid estuary under the impact of flow regulation

2013

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A B S T R A C TThe Jaguaribe River is the largest semi-arid Brazilian river and represents an important water source for the state of Ceará. The Castanhão Weir, built to regulate the flow of the Jaguaribe, began operating successfully in the 1990s. As a result, the hydrodynamic regime of the estuary has undergone alteration and is no longer subject to the former annual climatological variability of the dry and rainy seasons. This paper introduces an assessment of the changes in the hydrological conditions resulting from the construction of the weir and investigates the structure of the density stratification in the estuary. A field experiment was conducted at the end of the dry season in November 2009, during which salinity and temperature were monitored at different levels for three tidal cycles. The temporal variations in salinity and temperature during the tidal cycles were 16 psu and 1.5°C, respectively. The salinity exhibited a vertical variation of four units, while the temperature variation was much lower. Several stratification indicators were calculated from the observed density: the stratification coefficient, the Brunt-Väisälä frequency and the potential energy anomaly. The results showed that the parameters behave similarly, differences being observed only in their relative magnitudes. The vertical structure of the estuary exhibited marked stratification during the ebb tide but vertical homogeneity during both flood and high tide. With the regularized flow existing under present conditions, the estuary exhibits hyposaline and a partially mixed structure for the period studied, despite the typical expectation of a hypersaline and well-mixed vertical structure. R E S U M OO rio Jaguaribe é o maior rio do semi-árido brasileiro, constituindo uma importante fonte de água para o estado do Ceará. Na década de 1990 entrou em operação o Açude do Castanhão com o objetivo de regularizar a vazão do rio Jaguaribe, o qual obteve grande sucesso. Como consequência foi alterado o regime hidrodinâmico do estuário, o qual atualmente não está mais sujeito a variabilidade climatológica anual de estações seca e chuvosa. O presente trabalho apresenta uma avaliação da mudança do regime hidrológico antes e após a construção do açude, e investiga a estrutura de estratificação da densidade nos estuários. Foi realizado um experimento de campo em novembro de 2009, no fim da estação seca, quando a salinidade e temperatura da água foram monitorados em diferentes níveis durante três ciclos de maré. A variação temporal da salinidade e temperatura durante os ciclos de maré foram de 16 psu e 1,5ºC, respectivamente. A salinidade chegou a apresentar variação vertical de 4 unidades, enquanto que a variação da temperatura foi bem inferior. Foram calculados parâmetros indicadores da estratificação a partir da densidade: coeficiente de estratificação; frequência de Brunt-Väisälä; e a anomalia da energia potencial. Os resultados mostraram que os parâmetros comportam-se da mesma maneira, apenas com diferença da magnitude relativa de seus valo...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intra-tidal variation of stratification in a semi-arid estuary under the impact of flow regulation

2013

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“…In spite of the ecological and economic importance of Paraguaçu River estuary (127.9 km²), this river is located on the west side of Todos os Santos Bay and its origin is related to the drowning of a fluvial valley, during MiddleHolocene, controlled by the system of faults from the western portion of Recôncavo Bay, especially for the Maragojipe Fault (Carvalho 2000). The estuary is composed by three sectors: the lower course of the river (with 16 km long and average depth of 1 m), Iguape Bay (with 76.1 km² and an intertidal area of 53.7%) and by the Paraguaçu channel (with 18 km long and a average depth of 10 m), which establishes a connection between the Iguape Bay and Todos os Santos Bay, associated with the good state of conservation and the presence of a wide mangrove area (28 km²), favoring a high fishing productivity and the presence of a wide riverside community involved with artisanal fishing (Genz et al 2008). The municipality of Maragojipe, alongside the Iguape Bay, has come to be the second major fish producer in the Bahia State (BAHIAPESCA 1998), where in 2000 the IBAMA created the Iguape Bay Marine Extractive Reserve (Decree no number of 14/08/2000).…”

Section: Introductionmentioning

confidence: 99%

“…During the 80's, the Pedra do Cavalo Dam (PCD) was built about 28 km from de mouth of Iguape Bay, causing changes on the hydrological regime of the river. In 2005, a new change occurred due to the implantation of the Pedra do Cavalo Hydroeletric Power Plant (HPP), changing the fresh water flow to energy generation (Genz et al 2008). Nowadays there is a project in licensing for deployment of a port system within the estuary where extensive mangrove zone and estuarine sediment will be removed, setting one more impact scenario for the fish fauna as well as all the marine biota.…”

Section: Introductionmentioning

confidence: 99%

Estuarine ichthyofauna of the Paraguaçu River, Todos os Santos Bay, Bahia, Brazil

2010

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Estuaries are areas of recognized importance in the development and sanctuaries of fishes and also a great source of fishing resources. This article presents an inventory of fishes from the Paraguaçu River estuary, Todos os Santos Bay, Bahia, Brazil. 28 points comprising the saline sections that may exist in a tropical estuary were sampled quarterly from March 2009 to February 2010 with the aid of bottom gill nets, surface gill nets, seine net and casting net. A total of 4.097 individuals were captured, belonging to 7 species of Chondrichthyes and 117 species of Actinopterygii (83 genera and 49 families). Most of the geographical extent of the estuary was sampled by assessing large spatial variability in fish assemblage structure. The curve of species accumulation (rarefaction) had stabilization with ½ of the samples. The general structure of the assemblage is described and commented trough evidences for a new spatial organization of the fish fauna due to dam effects upstream the estuary. Resumo: Estuários são áreas de reconhecida importância no desenvolvimento e refúgio dos peixes e também grande fonte de recursos pesqueiros. Este artigo apresenta um inventário dos peixes do estuário do Rio Paraguaçu, Baía de Todos os Santos, Bahia, Brasil. 28 pontos constituindo as três seções salinas que pode haver em um estuário tropical foram amostradas trimestralmente de março de 2009 a fevereiro de 2010 com auxílio de redes de espera de fundo, de superfície, redes de arrasto manual e tarrafas. Um total de 4.097 indivíduos foram capturados, pertencendo a 7 espécies de Chondrichthyes e 117 espécies de Actinopterygii (83 gêneros e 49 famílias). A maioria da extensão territorial do estuário foi amostrada para acessar maior variabilidade espacial na estrutura da assembléia de peixes. A curva de acumulação de espécies (rarefação) apresentou estabilização com ½ das amostras. A estrutura geral da assembléia é descrita e comentada através de evidências para uma nova organização espacial da fauna de peixes devido a efeitos de barragem a montante do estuário. Palavras-Chaves: inventário, peixes estuarinos, distribuição espacial, efeitos a montante, nordeste brasileiro. Biota Neotrop., vol. 10, no. 4 Keywords: inventory, estuarine fishes, spatial distribution, effects upstream, brazilian northeast. REIS-FILHO Material and MethodsFishes were collected at 28 points within the Paraguaçu River estuary with quarterly samples between March 2009 and February 2010 (Figure 1). Several types of collectors were used: for marginal environments and with depths up to 3 m, trawl manual (12 m × 2 m with 12 mm mesh), gillnets (100 m × 3 m with 15 mm mesh) and flue (casting net ) (10 mm mesh). For environments with depth between 4 and 20 m, bottom gill nets (300 m × 3 m with 20 mm, 30 mm, 40 mm, 50 mm and 60 mm mesh) and surface gill nets (200 m × 4 m with 15 mm mesh) were used. In order to evaluate the ichthyofauna distribution in the estuary, this one was segmented into three sections (lower, middle and upper).

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“…Moreira et al (2014) experimentally showed high mortality rates of T. tagusensis and T. coccinea when exposed to low salinity (i.e., 0, 5, 10 practical salinity units). However, the Tubastraea invasion in the Paraguaçu estuary may have occurred due to the predominance of marine salinity levels (Genz et al, 2008;Reis-Filho et al, 2010;Genz & Lessa, 2015). This condition is likely to be associated with the building of the Pedra do Cavalo Dam in 1985 and Pedra do Cavalo Hydroeletric Power Plant in 2005 on the upper estuary (Fig.…”

Section: Discussionmentioning

confidence: 99%

New records of the alien cup-corals (Tubastraea spp.) within estuarine and reef systems in Todos os Santos Bay, Southwestern Atlantic

et al. 2016

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Background: The alien cup-coral Tubastraea spp. has been increasingly reported in the Southwestern Atlantic since the 1980s. More recently it was observed on the East coast of Brazil, the area with the highest biodiversity in the Southwest Atlantic. In the present study, we report the actual distribution of Tubastraea tagusensis and Tubastraea coccinea around Todos os Santos Bay (TSB), an important system in the Southwest Atlantic coast. Results: We mapped the geographic expansion of Tubastraea tagusensis and Tubastraea coccinea at 11 sites in estuarine and 2 in reef systems at TSB. Conclusions: The findings from our study will contribute to monitor alien expansion and implement management actions to control these invasions on the Brazilian coast.

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Vazão Mínima para Estuários: Um Estudo de Caso no Rio Paraguaçu/BA

Cited by 18 publications

References 8 publications

Intra-tidal variation of stratification in a semi-arid estuary under the impact of flow regulation

Intra-tidal variation of stratification in a semi-arid estuary under the impact of flow regulation

Estuarine ichthyofauna of the Paraguaçu River, Todos os Santos Bay, Bahia, Brazil

New records of the alien cup-corals (Tubastraea spp.) within estuarine and reef systems in Todos os Santos Bay, Southwestern Atlantic

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