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Suspended-Sediment Distribution Patterns in Tide-Dominated Estuaries on the Eastern Amazon Coast: Geomorphic Controls of Turbidity-Maxima Formation

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Graduate Program on Environmental Biology (PPBA), Federal University of Pará (UFPA), Alam. Leandro Ribeiro, s/n—Campus UFPA, Bragança CEP: 68600-000, PA, Brazil
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Institute for Coastal Studies, Federal University of Pará (UFPA), Alam. Leandro Ribeiro, s/n—Bairro Aldeia Campus UFPA, Bragança CEP: 68600-000, PA, Brazil
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Oceanographic Institute, University of São Paulo (USP), São Paulo CEP: 05508-120, SP, Brazil
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Graduate Program on Geology and Geochemistry (PPGG), Federal University of Pará (UFPA), Rua Augusto Corrêa, 01—UFPA-Guamá, Belém CEP: 66075-110, PA, Brazil
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School of Oceanography, University of Washington (UW), Box 357940, Seattle, WA 98195-7940, USA
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Author to whom correspondence should be addressed.
Academic Editors: Yong G. Lai and Achim A. Beylich
Water 2021, 13(11), 1568; https://doi.org/10.3390/w13111568
Received: 9 April 2021 / Revised: 18 May 2021 / Accepted: 28 May 2021 / Published: 1 June 2021
(This article belongs to the Section Water Erosion and Sediment Transport)
In tide-dominated estuaries, maximum-turbidity zones (MTZs) are common and prominent features, characterized by a peak in suspended-sediment concentration (SSC) associated with estuarine processes. The Brazilian Amazon coast includes many estuaries, experiencing macrotidal conditions. MTZs are expected to occur and are crucial for sediment delivery to the longest continuous mangrove belt of the world. The area is under influence of the Amazon River plume (ARP), the main SSC source, as local rivers do not deliver substantial sediment supply. To assess the processes that allow the ARP to supply sediment to the estuaries and mangrove belt along the Amazon coast, the results from previous individual studies within five Amazon estuaries (Mocajuba, Taperaçu, Caeté, Urumajó and Gurupi) were compared with regards to SSC, salinity, morphology and tidal propagation. This comparison reinforces that these estuaries are subject to similar regional climate and tidal variations, but that their dynamics differ in terms of distance from the Amazon River mouth, importance of the local river sediment source, and morphology of the estuarine setting. The Urumajó, Caeté and Gurupi are hypersynchronous estuaries where perennial, classic MTZs are observed with SSC > 1 g·L−1. This type of estuary results in transport convergence and MTZ formation, which are suggested to be the main processes promoting mud accumulation in the Amazonian estuaries and therefore the main means of mud entrapment in the mangrove belt. The Mocajuba and the Taperaçu estuaries showed synchronous and hyposynchronous processes, respectively, and do not present classic MTZs. In these cases, the proximity to the ARP for the Mocajuba and highly connected tidal channels for the Taperaçu estuary, assure substantial mud supply into these estuaries. This study shows the strong dependence of the estuaries and mangrove belt on sediment supply from the ARP, helping to understand the fate of Amazon River sediments and providing insights into the mechanisms providing sediment to estuaries and mangroves around the world, especially under the influence of big rivers. View Full-Text
Keywords: estuaries; suspended-sediment concentration; tidal prism; tides; turbidity estuaries; suspended-sediment concentration; tidal prism; tides; turbidity
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MDPI and ACS Style

Gomes, V.J.C.; Asp, N.E.; Siegle, E.; Gomes, J.D.; Silva, A.M.M.; Ogston, A.S.; Nittrouer, C.A. Suspended-Sediment Distribution Patterns in Tide-Dominated Estuaries on the Eastern Amazon Coast: Geomorphic Controls of Turbidity-Maxima Formation. Water 2021, 13, 1568. https://doi.org/10.3390/w13111568

AMA Style

Gomes VJC, Asp NE, Siegle E, Gomes JD, Silva AMM, Ogston AS, Nittrouer CA. Suspended-Sediment Distribution Patterns in Tide-Dominated Estuaries on the Eastern Amazon Coast: Geomorphic Controls of Turbidity-Maxima Formation. Water. 2021; 13(11):1568. https://doi.org/10.3390/w13111568

Chicago/Turabian Style

Gomes, Vando J.C., Nils E. Asp, Eduardo Siegle, José D. Gomes, Ariane M.M. Silva, Andrea S. Ogston, and Charles A. Nittrouer 2021. "Suspended-Sediment Distribution Patterns in Tide-Dominated Estuaries on the Eastern Amazon Coast: Geomorphic Controls of Turbidity-Maxima Formation" Water 13, no. 11: 1568. https://doi.org/10.3390/w13111568

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