QUALITATIVE ASSESSMENT OF CHANGES IN SEDIMENT DYNAMICS DUE DREDGING AND ROCK REMOVAL INTO A BACKWATER INFLUENCED SITE

Código

ENES20200038

Autores

Renato Souza Amorim

Tema

11 - MODELAGEM HIDROSSEDIMENTOLÓGICA

Resumo

The navigation in the Tocantins River is limited in part due to depth restrictions caused by rock outcrops and shoals during the low water seasons. Therefore, in order to increase the reliability of the system, the National Department of Transportation Infrastructure (DNIT) is planning to execute rock removal and dredging in a 43km long river reach between Marabá and Itupiranga, both located in the state of Pará. The planning phase started with an evaluation of the sediment transport conditions for the scenarios pre- and post-execution of the proposed interventions using a one-dimensional quasi-unsteady sediment transport model using the HEC-RAS version 5.07. As an input of this model, a one-dimensional hydraulic model was also developed which included the flow records from the Itupiranga gage (29200000; ANA, 2019) and stage records of the Tucuruí Reservoir from the ONS as the upstream and downstream boundary conditions, respectively. The sediment inputs used were the average bed gradation extracted from the river bed samples collected during a 2018 field campaign, suspended sediment total load and gradations from the Itupiranga gage. A 19-year period sediment transport simulation yielded negligible differences in the total sediment accumulation volume, its longitudinal depositional pattern, total shear stress and velocity?s magnitude, especially when compared with the changes in sediment dynamics induced by the Tucuruí dam construction and its operation