A case study of sediment transport in the Paranagua Estuary Complex in Brazil

• Three dimensional process-based model for flow in an estuary is set up.
• Field observations are reported.
• The transport of mixture and fine silt in the estuary is computed.
• Sediment activity is high in areas where large deposition is observed.

This paper presents transport of a mixture of cohesive sediments and sand in the Paranagua Estuarine Complex in the south of Brazil. The estuary houses a navigation channel from the Atlantic Ocean to a busy harbour. The channel requires frequent dredging owing to sediment deposition to maintain navigable depth for vessels. A three-dimensional process-based model for sediment transport coupled with wave-current models based on the Delft3D modelling system is constructed for the estuary. Extensive field data concerning current velocity, water level, salinity and suspended sediment concentration were collected. The flow model that is necessary to run the sediment transport model was calibrated and validated using field measurements. In this paper only the results concerning the sediment motion are presented. Calibration and validation of the numerical model show that the results of sediment transport represent the field conditions well. Additional support for the validity of the computed results is provided by field data pertaining to bathymetry acquired in 2005 and 2006. The present study gives insight into the motion of cohesive sediments and the morphological behaviour of the estuary, and should help operators maintain the channel for navigation.