scholarly journals Sediment input from the São Francisco River bank, Northeast Brazil, under low discharge period

2021 ◽  
Author(s):  
Francisco Sandro Rodrigues Holanda ◽  
Maria Hosana dos Santos ◽  
Janisson Batista de Jesus ◽  
Wadson De Menezes Santos ◽  
Edinaldo De Oliveira Alves Sena ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
River Discharge ◽  
River Channel ◽  
Sediment Supply ◽  
Northeast Brazil ◽  
Sao Francisco River ◽  
Soil Bioengineering ◽  
São Francisco River ◽  
Sediment Input ◽  
Bioengineering Techniques

The objective of this study was to evaluate the input of suspended sediment from the slope toe in the São Francisco River channel, in Northeast Brazil, under different soil bioengineering techniques. Sediments were collected in the years of 2013, 2014 and 2015, in five transects crossing the river channel. Sediment input in the sampling points was higher in the year of 2013, i.e., the year of the highest river discharge. Sediment supply to the river channel for a period of 3 years (2013, 2014 and 2015), was evaluated at 20, 40 and 60% depth, along five different transects (P1= riverbank, P2= beginning of the thalweg, P3= middle of the thalweg, P4= end of the thalweg, and P5 = margin of the side sandybar), oriented by the presence or absence of erosion control techniques (treatments) such as: 1-Natural Vegetated Slope; 2-Vegetated Riprap; 3-Eroded Slope; 4-Live Cribwall and 5-Vetiver grass Contour Line. Sediments input was different in all evaluated transects, and the one identified as Eroded Slope at 20% depth presented the lowest amount of suspended sediment load. There was a decrease in the total amount of suspended sediment in the evaluated periods, probably due to the progressive decrease in the river discharge, and the protection provided by the soil bioengineering techniques.

scholarly journals Curvas-chave de descargas de sedimentos em suspensão no Baixo São Francisco

2020 ◽  
Vol 13 (3) ◽  
pp. 1248 ◽  
Author(s):  
Solange Cavalcanti de Melo ◽  
José Coelho de Araújo Filho ◽  
Renata Maria Caminha Mendes de Oliveira Carvalho
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Gradual Reduction ◽  
Sao Francisco River ◽  
Sediment Loads ◽  
São Francisco River ◽  
Historical Series ◽  
Suspended Sediment Concentrations

RESUMOO conhecimento da análise quantitativa das concentrações de sedimentos em suspensão transportados pelo rio São Francisco bem como sua relação com as vazões é de muita importância, pois pode auxiliar na identificação dos efeitos da intervenção humana e ou ocasionados pelas condições naturais da região. As regiões a jusante dos barramentos no rio São Francisco apresentam como principal consequência a regularização das vazões e a diminuição das concentrações de sedimentos. O objetivo da pesquisa foi determinar as curvas-chave de sedimentos em suspensão (CCS) nas estações fluviométricas instaladas no Baixo São Francisco (BSF) após a barragem de Xingó. Para o estabelecimento dessas curvas foram utilizados dados de vazão e concentração de sedimentos em suspensão, obtidos do sistema Hidroweb no site da Agência Nacional da Água (ANA) no período de 1999 a 2018. Foram obtidas CCS para todo o trecho do BSF as quais apresentaram bons coeficientes de determinação. Na análise dos dados também foi possível perceber que nos últimos anos, desde 2013 houve redução gradativa das vazões disponibilizadas na barragem de Xingó. Consequentemente, houve também a redução gradativa das cargas de sedimentos em suspensão geradas nas estações de Piranhas, Traipu e Propriá, ou seja, os menores valores já registrados no BSF correspondendo as menores séries históricas tanto de vazão como de sedimentos em suspensão.  Keys curves of sediment discharges in suspension in the Lower São Francisco A B S T R A C TThe knowledge of the quantitative analysis of suspended sediment concentrations carried by the São Francisco River as well as its relation with the flows is of great importance, since it can help in the identification of the effects of human intervention and/or caused by the natural conditions of the region. In the downstream regions of the São Francisco riverbanks, the main consequence was the regularization of flow rates and the reduction of sediment concentrations. The objective of the research was to determine the key curves of suspended sediments (CCS) at the fluviometric stations installed in the lower São Francisco river after Xingó dam. For the evaluation, flow data and suspended sediment concentration were used. These data were obtained from the Hidroweb system on the website of the National Water Agency (ANA) from 1999 to 2018. CCS were plotted for all stretches and presented good coefficients of determination (R2). Based on the analysis of the data it was also possible to notice that in recent years, since 2013 there has been a gradual reduction of the flows available in the Xingó dam. Consequently, there was also a gradual reduction of suspended sediment loads generated at the Piranhas, Traipu and Propriá stations, that is, the lowest values already recorded in lower São Francisco, corresponding to the lower historical series of both discharge and suspended sediments.Keywords: dam, flow, sediments 

O RECIFE E O CENTENáRIO DE DELMIRO GOUVEIA EM PERNAMBUCO (1963)

2013 ◽  
Vol 10 (16) ◽  
Author(s):  
DILTON Cá‚NDIDO SANTOS MAYNARD
Keyword(s):  
Foreign Capital ◽  
Social Research ◽  
Northeast Brazil ◽  
Sao Francisco River ◽  
São Francisco River ◽  
Hydropower Potential ◽  
National Hero ◽  
Brazilian History ◽  
The City

Resumo: O artigo analisa as comemorações do centenário de Delmiro Gouveia, ocorridas em 1963. Considerado um mártir na luta contra brasileira o capital estrangeiro, o empreendedor pioneiro no aproveitamento do potencial hidrelétrico do rio São Francisco e o modernizador dos sertões alagoanos, Delmiro foi retomado como um á­cone nacionalista num contexto em que se discutiam os rumos para o desenvolvimento do Nordeste. As comemorações do seu centenário de nascimento, ocorridas em Pernambuco, envolveram esforços para atribuir ao ”coronel dos coronéis” o epá­teto de pioneiro na redenção regional. As diversas atividades constituintes destas celebrações revelam um embate não só pela confecção da memória do homenageado, bem como uma tensão entre transformá-lo em um herói nacional e utilizar a sua biografia para acentuar as particularidades do povo nordestino. Neste texto, o alvo das atenções é a ”Semana Delmiro Gouveia” (SDG), organizada pelo Instituto Joaquim Nabuco de Pesquisas Sociais (IJNPS), localizado no Recife, Pernambuco. Ali estiveram reunidos alguns dos principais estudiosos de Gouveia que, sob a coordenação de Gilberto Freyre e Mauro Mota, apresentaram as suas interpretações sobre a vida e a obra do ”Coronel dos Coronéis”. Palavras-chave: Delmiro Gouveia, Comemoração, Nordeste Brasileiro.  THE CITY OF RECIFE AND THE DELMIRO GOUVEIA CENTENARY IN PERNAMBUCO (1963)Abstract: This article analyzes the centenary celebrations of Delmiro Gouveia, occurred in 1963. Considered a martyr in the fight against Brazilian foreign capital, the pioneering entrepreneur in harnessing the hydropower potential of São Francisco River and the modernizing of Alagoas backwoods, Delmiro was included as a nationalist icon in a context in which they discussed the directions for the Northeast development. The celebrations of his centenary birth, occurred in Pernambuco, had involved efforts to give him the epithet pioneer in regional redemption. The various constituent activities of these celebrations reveal a clash not only by creation of the honoree's memory as well as a tension between turn it into a national hero and use his biography to emphasize the particularities of the northeastern people. This paper is mostly about the "Delmiro's Gouveia Week", organized by the Institute for Social Research Joaquim Nabuco, located in Recife, State of Pernambuco. In this place gathered some of the leading scholars of Gouveia, who, under the coordination of Gilberto Freyre and Mauro Mota, presented their interpretations of the life and work of biggest colonel in Brazilian history. Keywords: Delmiro Gouveia , Celebration, Northeast Brazil.  

Influence of river pattern and sediment input on estuary morphology

2020 ◽  
Author(s):  
Anne Baar ◽  
Elena Bastianon ◽  
Lisanne Braat ◽  
Daniel Parsons
Keyword(s):  
River Discharge ◽  
Large Scale ◽  
Numerical Models ◽  
Sediment Supply ◽  
Tidal Amplitude ◽  
Model Studies ◽  
Braiding Index ◽  
Sediment Input ◽  
River Pattern

<p>Alluvial estuaries are dynamic landscapes that are very sensitive to changes in boundary conditions such as river discharge and sediment supply. A better understanding of the influence of upstream river discharge and sediment input on the development of estuaries under various scenarios requires long-term morphodynamic models, to both predict future changes and improve geological interpretations by storing the stratigraphy. Past 1D model studies have shown that upstream river discharge has a significant effect on the equilibrium bed profile of estuaries, but these studies ignore the effect of 2D bar and channel formation. Using 2D numerical models to predict the development of these systems on the scale of millennia proved to be difficult, since the modelled morphology is very sensitive to the choice in e.g. sediment transport predictor and bed slope effect. In this study, we use the knowledge of previous research that determined best parameter settings for realistic river and bar patterns to model long-term and large-scale estuary morphodynamics in Delft3D. Our objective is to quantify the effects of river discharge and sediment supply on the shape of estuaries and its deposits. Firstly, we systematically varied upstream river width and tidal amplitude to examine the relation between upstream river pattern and estuary dimensions. We quantified e.g. braiding index, bar dimensions, and tidal excursion length. Results show that flood flow velocities and tidal prism are less influenced by river discharge than suggested by 1D models, and are significantly influenced by the braiding index of the river. With relatively high tides, estuary bar patterns depend on tidal amplitude, while with lower tides estuary depth and braiding index are related to upstream river width and discharge. Next steps will include varying discharge to study the effect on the rate of adaptation of the river and estuary, and varying the grain size of the sediment input at the upstream boundary. We will input coarse sediment to explore differences between fluvial deposits and tidal currents, and fine sediment to use the model for research related to biofilm.</p>

scholarly journals Sporolithon franciscanum sp. nov. (Sporolithales, Rhodophyta), a New Rhodolith-Forming Species from Northeast Brazil

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 199 ◽  
Author(s):  
Luis Alfredo S. Leão ◽  
Ricardo G. Bahia ◽  
Michel B. Jesionek ◽  
Walter H. Adey ◽  
Gabriel Johnson ◽  
...  
Keyword(s):  
New Species ◽  
Dna Sequences ◽  
Drainage Basin ◽  
River Mouth ◽  
Coralline Algae ◽  
Northeast Brazil ◽  
Anatomical Features ◽  
Sao Francisco River ◽  
São Francisco River ◽  
The World

This paper describes Sporolithon franciscanum, a new rhodolith-forming species of non-geniculate coralline algae found at depths between 47–52 m near the São Francisco river mouth, the second largest and the most extensive drainage basin in Brazil, and also at the Abrolhos Bank, in the world´s largest rhodolith beds. DNA sequences from plastidial psbA and rbcL markers indicate that the species is unique compared to all other Sporolithon species that have thus far been sequenced. Since morpho-anatomical features of the new species are shared with some other Sporolithon species, its identification was only confirmed by DNA sequences.

scholarly journals Circulation and salt balance in the São Francisco river Estuary (NE/Brazil)

RBRH ◽  
2017 ◽  
Vol 22 (0) ◽  
Author(s):  
Geórgenes Cavalcante ◽  
Luiz Bruner de Miranda ◽  
Paulo Ricardo Petter Medeiros
Keyword(s):  
River Discharge ◽  
Neap Tide ◽  
Spring Tide ◽  
River Estuary ◽  
Salt Transport ◽  
Salt Flux ◽  
Sao Francisco River ◽  
Tidal Cycles ◽  
São Francisco River ◽  
And Diffusion

ABSTRACT In order to evaluate how river discharge and tidal currents forcing influence the circulation and salt transport within the São Francisco River-Estuary, a two 25 hour surveys campaigns and along-channel profiles were performed in the estuary main channel (18/19 and 25/26 February 2014). The current intensity showed higher asymmetry between flood (v<0) and ebb (v>0) currents in spring tide (-0.6 and 1.1 m/s), as compared to neap tide (-0.4 and 1.0 m/s), which was attributed to the intense buoyancy energy enhanced by the stronger discharge in spring. Overall, salinity presented high stratified conditions and varied between 0.0<S<36.6, and 0.5<S<36.1 from surface to bottom, during spring and neap, respectively. Although river discharge reduced from spring to neap tide partially mixed-highly stratified conditions (type 2b) remained in both periods, with advection and diffusion contributing with 34% and 66% to the net upstream salt flux in spring, respectively, and 56% and 44% in neap tide, respectively, which was attributed to the balance of tidal and baroclinic forcing and river discharge. The dominant downstream advective salt transport in both spring (12.5 kg.m-1s-1) and neap (15.2 kg.m-1s-1) tidal cycles suggests that there is little salt accumulation inside the São Francisco estuary.

scholarly journals Avaliação de eficiência da implantação de técnica de bioengenharia de solos

2021 ◽  
Vol 14 (6) ◽  
pp. 3422
Author(s):  
Guilherme Matos Antônio ◽  
Francisco Sandro Rodrigues Holanda ◽  
Luiz Diego Vidal Santos ◽  
Bruno De Santana Mendonça ◽  
Rayssa Juliane Souza de Jesus ◽  
...  
Keyword(s):  
Soil Surface ◽  
Natural Area ◽  
Mechanical Reinforcement ◽  
Sao Francisco River ◽  
Soil Bioengineering ◽  
São Francisco River ◽  
Recovery Techniques ◽  
Degraded Area ◽  
Geomorphological Changes ◽  
Resistance To Penetration

O Baixo São Francisco está em constante dinâmica hidroambiental resultante das alterações promovidas na calha do rio, representadas pelos processos geomorfológicos ou por ações antrópicas como a construção das barragens que por sua vez provocou mudanças geomorfológicas resultando na aceleração de processos erosivos nas suas margens. O objetivo deste trabalho foi avaliar a implantação de técnicas de recuperação hidroambiental com uso de bioengenharia de solos na margem do rio São Francisco. A área estudada compreende um trecho do baixo curso do rio São Francisco, localizado no município de Amparo do São Francisco, no estado de Sergipe, nordeste do Brasil, onde técnica de bioengenharia de solos, como enrocamento vegetado, foi implementada no ano de 2011. Três grupos de indicadores individuais foram selecionados que juntos contribuíram para a avaliação da Recuperação da Área Degradada relacionados à qualidade do solo, como resistência do solo à penetração e Velocidade de Infiltração Básica, à recuperação da biodiversidade como banco de sementes e a regeneração natural da área por meio de indicadores como composição e cobertura linear de espécies. A metodologia empregada contempla uma avaliação dos resultados originados do uso da biotécnica a partir da identificação da contribuição da vegetação que auxilia na contenção de taludes, uma vez que a cobertura vegetal protege a superfície do solo contra ações erosivas como o vento e a água da chuva. O reforço mecânico trazido pelo sistema radicular das plantas contra cisalhamento do solo se mostrou pela menor resistência à penetração do solo e maior Taxa de infiltração.     Evaluation of efficiency of the implementation of soil bioengineering techniqueA B S T R A C TThe Lower São Francisco is in constant hydro-environmental dynamics resulting from the changes promoted in the river channel, represented by geomorphological processes or by anthropic actions such as the construction of dams that in turn caused geomorphological changes resulting in the acceleration of erosive processes on its banks. The objective of this work was to evaluate the implementation of hydroenvironmental recovery techniques using soil bioengineering on the bank of the São Francisco River. The studied area comprises a stretch of the low course of the São Francisco River, located in the municipality of Amparo do São Francisco, in the state of Sergipe, northeastearn Brazil, where soil bioengineering technique, such as vegetated rockfill, was implemented in 2011. Three groups of individual indicators were selected that together contributed to the assessment of Degraded Area Recovery related to soil quality, such as soil resistance to penetration and Basic Infiltration Speed, to the recovery of biodiversity as a seed bank and the natural area regeneration through indicators such as composition and linear species coverage. The employed methodology includes an evaluation of the results from the use of biotechnology based on the identification of the vegetation contribution that helps to contain slopes, since the vegetation cover protects the soil surface against erosive actions such as wind and rainwater. The mechanical reinforcement brought by the root system against soil shear was shown by the lower resistance to soil penetration and a higher infiltration rate.Keywords: Degraded Areas Recovery, erosion, São Francisco River

scholarly journals Local representations of change and conservation of the riparian forests along the São Francisco River (Northeast Brazil)

2014 ◽  
Vol 45 ◽  
pp. 1-12 ◽  
Author(s):  
Taline Cristina da Silva ◽  
Marcelo Alves Ramos ◽  
Maria Luiza Schwarz ◽  
Ivan André Alvarez ◽  
Lúcia Helena Piedade Kill ◽  
...  
Keyword(s):  
Riparian Forests ◽  
Northeast Brazil ◽  
Sao Francisco River ◽  
São Francisco River ◽  
Local Representations
Sign in / Sign up

Export Citation Format

Share Document