Influence of long jetties on estuarine and coastal hydrodynamics in a microtidal estuary

Abstract

Coastal areas are extremely important regions for social and economic development, therefore vulnerable to human impacts as port settlement and development as well as construction of coastal structures. The aim of this study is to assess changes on estuarine and coastal hydrodynamics due to the construction of long jetties at the Patos Lagoon inlet (Brazil). The Patos Lagoon estuary has a remarkable socio-economic and ecological importance, yet no study focused on the original impact of the jetties construction at its inlet, which occurred between 1911 and 1917. Through the application of a three-dimensional numerical model, we assess its hydrodynamic changes based on pre- and post-jetties scenarios. The TELEMAC-3D was calibrated and validated against in situ measured data. The morphological changes caused by the jetties induced a reduction of the ebb and flood current velocities along the channel, a decrease in the capacity of salt transport, and a reduction in salinity values and saline incursion. The presence of jetties, however, led to the intensification of current velocities in the plume jet and consequently an increase in continental water offshore. The changes presented here for the Patos Lagoon estuarine and coastal areas and the possible repercussions for the maintenance of essential conditions in this environment revealed the importance of evaluating ecological, sedimentary and morphological aspects prior to coastal constructions. Additionally, results of this study highlight the importance of investigating past human-induced impacts in order to provide useful information for future sustainable development works in coastal zones.