Sedimentary Dynamics of the Mondego estuary

Abstract

The Mondego estuary is composed of two subsystems with contrasting sedimentary. hydrodynamic, physical and chemical characteristics. Is affected by a mesotidal, semi-diumal, regime.The Mondego subsystem, currently including a navigation channel, is exclusively bounded by artificial banks.The Pranto subsystem is more shallow and less affected by anthropogenic interventions. The aims of this study are the recognition of freshwater/saltwater circulation and the analysis of surface sediments in order to propose a pattem of sediment circulation. Studies on grain-size, mineralogy and quartz-grains surface textures and roundness of surface sediment sam pies were conducted and a detailed grain-size map was obtained. Most of the data was acquired in 1994 to 1996, at low and high tide of neap and spring tides, including measurements in selected locations, at several depths, of conductivity. salinity. temperature, current velocity/direction, turbidity. concentration of sittlclay. pH and Eh.The Mondego subsystem is under significant tidal control, being well mixed with reduced fluvial flow and stratified during seasonal floods. The hydrodynamic pathways (tidal vs. fluvial, this prevailing in the northem margin) causes clear contrast in sediment transport The Pranto subsystem is mainly brackish, well mixed, with strong tidal hydrodynamic, physical and chemical fluctuations; fluvial floods rarely have high discharges.The well developed Gala flood tidal delta, and the extensive saltmarsh and intertidal mudflat dissected by tidal creeks, are the main features of this subsystem. The Pranto subsystem is tidal dominated, while the Mondego subsystem is both tidal or fluvial dominated.

New physical and biological evidence of lateral transport affecting dinoflagellate cyst distribution in the benthic nepheloid layer along a land-sea transect off Figueira da Foz (Atlantic Iberian margin)

“…The closest contribution of freshwater and fluvial sediments to the study area is the Mondego River, with a catchment basin of 6670 km 2 and an estimated annual average runoff up to ~150 m 3 s -1 (Cunha and Dinis, 2002). However, the Douro and Minho Rivers further north of the study site are the greater contributors to the WIBP on the NW Iberian coast (Mendes et al, 2016).…”

Environmental Factors Affecting Spatial Dinoflagellate Cyst Distribution in Surface Sediments Off Aveiro-Figueira da Foz (Atlantic Iberian Margin)

“…From south to north, the main freshwater sources in the study area are the Mondego river and the Ria de Aveiro (Figure 1B). The Mondego river has a catchment basin of 6670 km 2 and an annual average runoff of 500 m 3 s −1 (Cunha and Dinis, 2002;Marques et al, 2002). Several rivers drain to the Ria de Aveiro -an estuary with coastal lagoon characteristics -with a total catchment area of ∼3600 m 2 , Vouga being the largest river, with an average runoff of 29 m 3 s −1 (Dias et al, 1999;Da Silva and Oliveira, 2007).…”

Assessment of Dredging Scenarios for a Tidal Inlet in a High-Energy Coast

“…The Mondego River estuary can be morphologically classified as a bar-built estuary after [21,22], having a length of 26 km, and it splits in two branches at 7 km upstream of the mouth, but these converge again downstream in an old tidal mudflat. The dams built upstream in the 1970s control its fluvial flow.…”