Sediments flux through the Aveiro harbour jetties: patterns of accretion and erosion

Abstract

Measurements of suspended sediment concentrations (SSC) in the Aveiro inlet during eight tidal cycles, comprehending spring and neap tides throughout winter and summer oceanographic regime, in 2006 and 2007, were performed. The SSC results show significant temporal variability, suggesting that higher fluxes of sediments through the Aveiro inlet occur in general during the winter spring tides. In these events higher volume of sediments can be imported from the ocean and introduced in the lagoon. Textural, mineralogical, geochemical and microfaunal studies of bottom sediments in the lagoon entrance area evidence the main areas where the sediments imported from the ocean are being accumulated: near the South Jetty and at the western side of Mira Channel. The sediments accretion in these areas contributes to the stabilization of the engineering structures of Aveiro Harbour. The high tidal current velocities contribute to the erosive character which dominates, at the central entrance channel, between both breakwaters and close to the North Jetty. These results show the vulnerability to erosion of some areas of North Jetty.