Influence of tides and river inputs on suspended sediment transport in the Ria de Aveiro lagoon, Portugal

Abstract

In this work the influence of tides and river inputs on suspended sediment distribution in the Ria de Aveiro, a shallow lagoon situated in the Northwest of Portugal, has been studied. Particular emphasis has been placed on Laranjo Bay, a sub-system of the lagoon from a bio-geophysical point of view. The study is based on both data analysis and sediment transport modelling. Tides are the major factor influencing the hydrodynamics of the lagoon. Their effects are important even at the upper reaches of the different channels, where salinity, temperature and sediment concentrations change during the tidal cycle. Sediment concentration shows both semi-diurnal and fortnightly periodicity. Highest values are found in the northern channels due to erosion induced by high current speeds in shallow areas. Erosion and deposition are the dominant processes determining suspended sediment transport in the lagoon.