Impacts of dredging on the hydromorphodynamics of the Patos Lagoon estuary, southern Brazil

Martelo, André Felipe; Trombetta, Thaísa Beloti; Lopes, Bruno Vasconcellos; Marques, Wiliam Correa; Möller, Osmar Olinto

doi:10.1016/j.oceaneng.2019.106325

Cited by 23 publications

(9 citation statements)

References 13 publications

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“…This may explain the higher abundance of organic matter percentages on winter and spring, as the drainage basin provide large amounts of suspended sediments that will deposit in the less hydrodynamic zones of the estuary. In addition, high peaks of current velocity in winter and early spring reflect the low salinity intrusion in the estuary, being the seasonal variability of estuarine discharge related with the variability of river discharge inside the Lagoon (Martelo et al, 2019). Coinciding with this, Pino et al (1999) reported high seasonality in the organic matter percentages and muddy sediments with peaks in winter for the Queule estuary (Chile).…”

Section: Discussionmentioning

confidence: 86%

“…Wind is the main factor driving the circulation patterns of the Patos Lagoon in periods of low river discharge (Möller et al 2001;Martelo et al, 2019). The NE winds, predominant along year, form a pressure gradient that favors the seaward flows, while SW winds predominant in winter and spring favors the landward flows (Möller et al, 2001;Fernandes et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

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Spatial and temporal variations of sediments in a subtropical microtidal estuary

et al. 2021

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Sediment dynamics are determined by the synergy between the hydrodynamic condition and sediment properties. This study analyzed, between the years 2015-2017, the spatial and temporal changes in sediment texture of a shallow embayment in the Patos Lagoon estuary (Southern Brazil), and the influence of environmental parameters in these variations. Two areas were selected: an area more exposed to the estuary main channel dynamics and NE winds, and the other protected from them by islands. Each area was divided in shallow (mean depth <2m) and deeper zones (mean depth ≥2 m). The organic matter content presented a spatial and temporal variation, with maximum values higher than previously reported. Due to elevated rainfall rates during the winter and spring of 2015, higher values of fine sediments and organic matter were recorded, mainly at deeper zones. The protected area presented smaller grain sizes and their variability was correlated with wind speed and direction. While in the exposed area the water depth has a higher influence in the granulometric variations, decreasing grain sizes with depth increases. The higher seasonality in the granulometric variation was observed in the deeper zones, which presented the smaller grain sizes and lower values of asymmetry, decreasing these values in winter and spring. In conclusion, few centimeters in water depth may cause large changes in bottom types (or in the relative amount of sand, silt and clay) of shallow estuarine areas. From the environmental variables measured, wind, rainfall and bathymetry were the most influential in the temporal variation of the sediments, while hydrodynamic exposure on the spatial differences.

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Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Spatial and temporal variations of sediments in a subtropical microtidal estuary

et al. 2021

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“…The Port of Rio Grande, the second most important port in Brazil for the development of Brazilian international trade (Rio Grande do Sul, 2019), is near the mouth of the lagoon at the Atlantic Ocean. Patos Lagoon is navigable by vessels from the mouth to Guaíba Lake, northwest of the lagoon (Martelo et al, 2019). The so-called Guaíba Lake is the main source of fresh water supply to the metropolitan area of Porto Alegre, the State capital, with a population of about 4.3 million inhabitants (Bendati et al, 2000).…”

Section: Patos Lagoon Study Casementioning

confidence: 99%

On characteristic hydraulic times through hydrodynamic modelling: discussion and application in Patos Lagoon (RS)

Aguilera¹,

Santos²,

Rosman³

2020

Rev. ambiente água

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Although the analyses of characteristic hydraulic times are important diagnostic tools for studying water mass exchanges and identifying areas prone to stagnation that are potentially subjected to eutrophication effects, their concepts and uses are often misinterpreted. This paper compares similarities and differences between widely used characteristic hydraulic times, CHT, known as Residence Time, Times of Water Renewal Rates and Water Age. A proper definition for each of these characteristic hydraulic times is stated to avoid the existing confusion with multiple concepts in the literature. Methodologies to compute these CHT through hydrodynamic modelling systems are presented and, in order to enhance understanding, applied to three idealized cases in steady flow channels: (1) Channel with uniform flow; (2) Channel with a lateral inflow; and (3) Channel with a lateral embayment. Finally, a practical example is discussed by applying the methodologies to the Patos Lagoon (RS). The results for the idealized channel cases are non-intuitive and this theoretical discussion clarifies the interpretation and uses of different timescales and outlines the Water Age as the more versatile and multifunctional timescale if compared to the others addressed here. The results for the Patos Lagoon exemplify the valuable information that CHT can offer for environmental management in natural water bodies.

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“…It has also been reported that the extension of jetties does not change inlet flow propagation and water quality, although changes in the topography increase current velocities and salinity values [11]. Dredging activities can cause variations in the estuarine physical parameters and suspended sediment concentration; moreover, they can promote fast siltation in the harbor waterway after the end of the dredging operations [12].…”

Section: Introductionmentioning

confidence: 99%

Impact of Jetty Configuration Changes on the Hydrodynamics of the Subtropical Patos Lagoon Estuary, Brazil

ANTONIO

Fernandes

Muelbert

2020

Water

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Coastal infrastructure alterations, such as jetty expansions, are designed to provide improvements to natural dredging and safety of marine access and to maximize the management and efficiency of ports. Furthermore, these alterations have the potential to cause significant environmental changes to estuaries and adjacent coastal areas. Here, the hydrodynamics of Pathos Lagoon was investigated before and after the jetty alterations, where the jetty was increased by approximately 10–18% and the mouth width was reduced by 15%. The TELEMAC-3D numerical model was calibrated and validated using the field data, and then simulated for characteristic low and high extreme discharge years for the old and new jetty configurations. Results showed a flow reduction of approximately 20% both in the ebb and flood conditions in the new configuration, which was accompanied by a slight change in the propagation angle of the western jetty current. Reduction of the saltwater intrusion was registered during both the high and low discharge conditions with the new jetty configuration. During the high discharge periods with NE winds, saltwater intrusion did not reach the previous estuarine inland boundary. During the period of low discharge with SW wind, salinity did not reach further than 180 km inland. Reduced saltwater intrusion was estimated landwards and in the shallow embayments. The horizontal stratification structure of the salinity changed, with the partial centralization of the flow in the access channel. The observed hydrodynamic changes from the infrastructure modifications could affect the estuarine ecosystem by increasing the sediment retention, reducing the transport of marine organisms and water properties into the estuary. This study contributes not only to the understanding of hydrodynamic changes but also to the potential optimization of estuarine and coastal management strategies.

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Impacts of dredging on the hydromorphodynamics of the Patos Lagoon estuary, southern Brazil

Cited by 23 publications

References 13 publications

Spatial and temporal variations of sediments in a subtropical microtidal estuary

Spatial and temporal variations of sediments in a subtropical microtidal estuary

On characteristic hydraulic times through hydrodynamic modelling: discussion and application in Patos Lagoon (RS)

Impact of Jetty Configuration Changes on the Hydrodynamics of the Subtropical Patos Lagoon Estuary, Brazil

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