Proceedings of the 17 th Physics of Estuaries and Coastal Seas (PECS) conference, Porto de Galinhas, Pernambuco, Brazil, 19–24October2014 Hydrodynamic modeling and residual velocities in Santos Estuarine Complex (SP, Brazil) CARNEIRO, J. C. 1 , MOLINAS, E. 1 , NEMES, D. D. 1 , GALLO, M. N. 1 , VINZÓN, S. B. 1 , ARAÚJO, A. A. M 1 . 1 Laboratory of Dynamics Cohesive Sediments Department of Water Resources and Environment - Polytechnic School Area Coastal & Oceanographic Engineering - PENO / COPPE Federal University of Rio de Janeiro E-mail: julianecastrocarneiro@gmail.com Keywords: estuaries, Delft 3D, port siltation, tidal asymmetry SUMMARY Coastal, lagoon and estuarine regions are important and require proper management of its resources. The Port of Santos (SP), located southeast of Brazil, is one of the largest and most important ports in Latin America, with constant anthropogenic changes, mainly related to shipping activities such as frequent dredging, and the presence of Cubatão industrial complex. The port interests make efforts to characterize the dynamics of sediment are focused on navigation and berthing areas, but it is necessary also researches in estuarine complex. In the context of past research, the definition of the background residual velocities, important in local hydrodynamics, is still a gap in this region. Thus, this study aims to understand the circulation pattern of the Santos estuary complex with a focus on the relationship between it and adjacent channels. For this, the Delft 3D model was used in order to identify the background residual velocities, and tidal asymmetry, that governing sediment transport and mechanisms of sedimentation Santos estuary. Different scenarios were considered, spring and neap tide, negative and positive tidal asymmetry. The main contribution of this study is applied to the understanding of the local hydrodynamics, navigation safety ever larger ships and construction of new port terminals in the region of Santos. 1. INTRODUCTION The sediment transport in estuaries is the result of complex interactions between the bathymetry and the local hydrodynamics, mainly related to variations in tide, river discharges, density differences and waves. When the tide is the most important forcing, the residual transport is determines the morphological evolution, in which case, what causes such transport in estuaries is tidal asymmetry [5]. Tidal asymmetry term is used to refer the distortion of the tidal wave through nonlinear interaction which causes the flood period is different from the ebb tide period. There is a relations between changes in asymmetry of the tide and the morphological development of the estuary, direct relation with the residual sediments flux [7], apart from that small asymmetries can responsible for major differences in transportation resulting sediment [3]. Tidal current asymmetry is usually associated to nonlinear tidal interactions in shallow water, generating compound tides and overtides. According the HOITINK et al. [1], tidal asymmetry is not only caused by nonlinear tidal interaction, but is also generated by astronomical tides in absence of shallow water effects. In particular, the K1, O1, and M2 constituents give an asymmetrical periodic flow pattern, with the largest peak velocities persistently in the same direction. The tide in entrance of Santos Estuarine Complex is mixed, mainly semidiurnal tides and in according with NIDZIEKO [4], it arises from both the interaction of principal tides and the higher harmonics generated by distortions within the estuary. Thus, the objective of this study is to characterize the variability of the residual transport linking with tidal level and asymmetry.