Long-Term Temporal Variability of the Freshwater Discharge and Water Levels at Patos Lagoon, Rio Grande do Sul, Brazil

Barros, G. P.; Marques, Wiliam Correa

doi:10.1155/2012/459497

Cited by 9 publications

(7 citation statements)

References 44 publications

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“…The difference value gradually reduces from the north part of the lagoon until it reaches the minimum value of 0 meters in the lagoon's mouth and oceanic area. The results from the numerical simulations corroborate the results obtained by Barros and Marques [15], which determined that in long time scales, the freshwater discharge is responsible for 50% of the water level fluctuation in the estuarine region and 80% at the lagoonar portion.…”

Section: Water Levelsupporting

confidence: 87%

“…The salinity distribution demonstrated the same pattern observed by another authors [15] [17] [19] [23], in which the salinity at Patos Lagoon is proportionally inverse to the freshwater discharge. The simulation B presented lower salinity values than simulation A in most of the estuarine region, except for two regions with positive difference values on the Mangueira Bay and the west region of the Marinheiros Island (areas in red).…”

Section: Surface Salinitysupporting

confidence: 86%

“…On interannual time scales, the freshwater discharge is responsible for 50% of the water level fluctuations at the estuary and 80% at the lagoonar region [15]. Barros and Marques [15] verified the occurrence of interannual events (reaching from 1.5 to 6 years) associated with ENSO controlling the freshwater discharge and water levels at Patos Lagoon.…”

Section: Description Of the Study Areamentioning

confidence: 99%

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Influence of the Freshwater Discharge on the Hydrodynamics of Patos Lagoon, Brazil

Barros¹,

Marques²,

Kirinus³

2014

IJG

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Patos Lagoon is a very dynamic environment presenting hydrodynamic fluctuations from synoptic to decadal timescales. Thus, understanding the processes that determine the long term variability is fundamental for the correct coastal planning and management of this region. The main objective of this study is to understand how the freshwater discharge of the main tributaries controls the estuarine hydrodynamics of the Patos Lagoon, when considering long term timescales. Two numerical simulations were carried out using the TELEMAC3D numerical model, the former using freshwater discharge from 1940 to 1973 year (simulation A), and the second simulation using data between 1974 and 2006 year (simulation B). These two periods were selected because before (after) 1973 year, the annual mean freshwater discharge was lower (higher) than the mean value for the whole period (1080 m 3 /s). The navigational channel discharge, water level, salinity and current velocity differences between both simulations were analyzed. Ebb conditions prevailed over flood conditions for both simulations, but simulation B presented a higher volume of freshwater exported through the coastal zone. Water level differences demonstrated higher values (0.08 meters) close to the Guaiba River, which is the main tributary of the study region, and lower values were observed near to the Patos Lagoon mouth (0 meters). The most significant differences in the mean bottom and surface salinity were observed in the central zone of the estuary and at the Barra Breakwaters. Simulation A presented higher saline intrusion due to lower freshwater discharge, while simulation B showed an increase in the coastal plume intensity, caused by the higher freshwater discharge. The hydrodynamical simulations demonstrated with precision that the freshwater discharge intensity determine the vertical stratification of the estuary.

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Section: Water Levelsupporting

confidence: 87%

Section: Surface Salinitysupporting

confidence: 86%

Section: Description Of the Study Areamentioning

confidence: 99%

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Influence of the Freshwater Discharge on the Hydrodynamics of Patos Lagoon, Brazil

Barros¹,

Marques²,

Kirinus³

2014

IJG

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“…The circulation pattern is more intense in the shallow region near the 25m isobath (Figure 4a). The salinity in this area changes smoothly towards fall, winter and spring (Figure 4 c, d, e), although during winter the regular presence of alternating wind directions results in a prevailing south-northern wind-driven current forced by the passage of meteorological systems that promotes the dispersion of the Patos Lagoon plume northwards (Marques et al, 2010a), associated with high freshwater discharge (Barros and Marques, 2012). The opposite is seen in the summer (Figure 4 f), when the northern winds prevail upon the Patos Lagoon plume enhancing the salinity on the coast in addition to lower river discharge into the lagoon.…”

Section: Resultsmentioning

confidence: 98%

Investigation of persistent coherent structures along the Southern Brazilian Shelf

et al. 2018

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The freshwater-influenced region of the Patos Lagoon discharge to the Southern Brazilian Shelf (SBS) is a region of complex fluid dynamics. Seasoning and synoptic variable winds and coastal current conditions create an alternating flow pattern. The aim of this paper was to investigate the occurrence of persistent coherent structures in this environment. A numerical approach was chosen to describe the main hydrodynamic features of the region during a climatological year. The open-source finite-element code Telemac-Mascaret was applied to the three-dimensional domain. In addition the two-equation k-epsilon model described the turbulence mechanisms. The presence of persistent high-turbulent structures was identified within the study area. These occur as a strong curvilinear disturbance characterized by higher turbulent production and dissipation rates, which increase local mixture. As a result, upward circulation flow was observed, which may be due to irregularities in bottom topography associated with wind-induced stress forces. These results increase the information about the circulation structures of the study area by means of numerical modelling analysis.

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“…In this work, the use of three-dimensional hydrodynamic simulations and simulations of the waves are of great importance on account of the difficulties of visualization and interpretation of data in this environment, which has a large temporal and spatial variability of physical characteristics in terms of external factors such as wind and river discharge [10].…”

Section: Methodsmentioning

confidence: 99%

The Contribution of Waves in Mixing Processes of the Patos Lagoon Plume

Kirinus¹,

Marques²,

Costa³

et al. 2012

IJG

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The analysis of wave effects above salinity is important in order to define mixing processes and their potential to change density gradients, since action in the region of the Patos Lagoon plume is highly dynamic. This paper aims to evaluate the influence of waves on the mixing pattern of the adjacent continental shelf. Constantly marked by tides and circulation variations, changing from flood to ebb tide, salinity stands as a major parameter for analysis. The study is based on hydrodynamic numerical modeling experiments using the TELEMAC3D model and waves generated by the wind using the TOMAWAC coupled model. The comparison between the situations considering the waves generated by the wind and without waves was made through time series analysis, stratification series, transversal cross sections, longitudinal cross sections, salinity mean fields and diagrams by Richardson and Brünt-Väisäläs frequency parameters. With the cross sections analysis, the mixing effect generated by the waves was observed, demonstrating clearly that the waves were capable of raising the superficial salinity in regions far from the Patos Lagoon entrance, while at the entrance, the wave effects enhanced the mixing on the deepest layers, decreasing the saline intrusion and expanding the plume more radially on the surface. The space-temporal diagrams were effective to demonstrate the modulation effect of the waves over the salt mixing of saline waters, revealing that wave effects decrease the stratification as well as the Brünt-Väisäläs frequency and increase the period of buoyancy, due to the mixing increase

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Long-Term Temporal Variability of the Freshwater Discharge and Water Levels at Patos Lagoon, Rio Grande do Sul, Brazil

Cited by 9 publications

References 44 publications

Influence of the Freshwater Discharge on the Hydrodynamics of Patos Lagoon, Brazil

Influence of the Freshwater Discharge on the Hydrodynamics of Patos Lagoon, Brazil

Investigation of persistent coherent structures along the Southern Brazilian Shelf

The Contribution of Waves in Mixing Processes of the Patos Lagoon Plume

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