MID TERM SIMULATION OF SUSPENDED SEDIMENT TRANSPORT AND BED EVOLUTION FOR THE PATOS LAGOON ESTUARY

André Felipe Martelo,Osmar Olinto Moller Jr,Wiliam Correa Marques

doi:10.21575/25254782rmetg2019vol4n2792

André Felipe Martelo, Osmar Olinto Moller Jr + Show 1 more

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https://doi.org/10.21575/25254782rmetg2019vol4n2792

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Abstract

Worldwide harbors are settled inside estuarine areas due the protection function of these environments against oceanic waves and therefore are subjected to the hydrodynamic processes that provide morphodynamic changes in sediment distribution and bed evolution. Understanding the dynamic of sediments and the bed evolution at estuaries is of crucial importance on maintenance of fairways and harbor docks. We modeled using the finite element technique 1005 days of hydro and morphodynamic of the Patos Lagoon estuary, in order to identify the critical deposition areas inside the Rio grande harbor fairway. Therefore, a hydrodynamic model, TELEMAC 3D, and a morphodynamic, Sisyphe, were applied in order to acquire the bed evolution and sediment distribution of the area using different data sources for the oceanic, atmospherical and continental boundary conditions. The results, present that clay is being deposited at deeper parts of the channel. Bed evolution results indicate siltation/erosion process where silt/clay is being deposited. Sedimentation rates were calculated based on the bed evolution results as well. The validation procedure showed good representation by the models of the physical aspects of the environment.

Highlights

Estuaries are coastal transitional environments by which sediment is transported from high lands, by the rivers, to the sea
1005 days of suspended sediment transport were modeled at the estuary channel of the Patos Lagoon
We can notice that clay suspended concentration at the Bacia do Porto Novo (BPN) point are higher than the silt ones, indicating that clay is been transported all over the water column, while silt can be found deposited at the bottom

Summary

Introduction

Estuaries are coastal transitional environments by which sediment is transported from high lands, by the rivers, to the sea. The relative shallow waters and harbor conditions that most estuaries present make them useful environments for human activities like installation of harbors, and shipyards and the maintenance of navigable fairways due offshore logistic of goods and oil. In many estuaries the suspended sediment concentration (SSC) increases in the upstream direction where a turbidity maximum zone (TMZ) is found at the head of the salt intrusion, forced by the entrance of sea water in the system (DYER, 1995). The distribution and magnitude of the TMZ are affected by seaward and landward sediment supply summed with variations in river discharge. Changes on natural patterns of both SSC and TMZ can affect sediment distribution and the morphodynamics of the environment. Human interventions, like deepening and widening of natural channels and land reclamation, can impact the natural distribution of the TMZ, resulting in ecological and infrastructural impacts (de Jonge et al, 2014)

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