Swash platform morphology in the ebb-tidal delta of the Barra Nova inlet, South Portugal

A fieldwork study of an artificially created inlet cut in the barrier island system of the Ria Formosa (South Portugal) was carried out from January to March 1999. This study focused on the updrift swash platform associated with the ebb-tidal delta. The area was monitored during a month with fair weather conditions studying morphodynamics, sedimentary dynamics and hydrodynamic measurements. The results were used to establish a sedimentary budget of the swash platform and to quantify the morphodynamics. A strong accretion was observed on the swash platform, which corresponded to the volume of sediment provided by the longshore drift on the adjacent updrift coast. A redistribution of sediment was observed on the platform, changing the orientation of the main swash platform axis. The swash bars forming this area are very dynamic (20 m migration in 8 days), and the entire swash platform migrated toward the inlet resulting in progressive closure of the system. Characteristics of the inlet and morphodynamics of the swash platform were used to validate a conceptual model of by-passing by ebb-tidal delta breaching for this system

Sediment transport pattern at the Barra Nova inlet, south Portugal: a conceptual model

The Barra Nova inlet, in south Portugal, is known to migrate progressively southeastwards under wave action. The morphodynamics of this system during a representative year suggests that this long-term evolution is dependent on a seasonal behavior of the tidal inlet which can be described through a three-stage model of post-storm, transition and extended fair-weather conditions. Processes involved in this evolution indicate that the historical migration of the Barra Nova is not dependent on the longshore drift forcing constricting the channel on the updrift coast, but rather on the adjustment of the system to a major erosion of the downdrift coast during short storm events

Longshore sediment movements from tracers and models, Praia de Faro, South Portugal

This work aims to improve the knowledge of sediment circulation in the coastal zone, focusing on the quantification of sediment movement due to longshore drift. The studied field site is the Praia de Faro beach on the Peninsula do Ancão in Algarve (Portugal), which is located on the updrift coast of the Barra Nova tidal inlet. The main objective of the study was to quantify the sediment transport rate that will enter in the inlet system.Measurements were undertaken during low hydrodynamic conditions prevailing in this area and permitted to estimate a longshore transport rate of 2.6–4.2 m/s, consistent with other transport estimations in Algarve. Four theoretical models for longshore transport rate calculation were confronted to tracer results to choose a extrapolation tool. Kamphuis (1991) formula appeared to be the more appropriate in this area. It was used to extrapolate the results in order to be compared to the observed morphological evolution. The calculated short term sediment flux (10500 m3/month) corresponds to the accretion on the updrift swash platform of the Barra Nova tidal inlet and is thus considered to be the contribution of the adjacent coast to this system. Moreover, the estimated longshore transport rate permit us to predict a spit progradation of 60–70 m/year. This result is consistent with the observed migration rate of the Barra Nova inlet during the last 25 years. This study shows that, with a good knowledge of the environmental context, sediment fluxes obtained by sand tracers are accurate enough to estimate the long term longshore transport and long term morphological response of a stretch of shoreline

Tidal inlet function: field evidence and numerical simulation in the INDIA project

In recognition of the environmentally sensitive nature of inlets and of a requirement to improve present knowledge of their function, the INDIA project has studied a small natural tidal inlet located in the Ría Formosa, Algarve, Portugal. The project has used state-of-the-art field equipment to study present day processes, and a range of numerical models to extend the spatial and temporal range of the measurements. Underpinned by knowledge of inlet evolution over several years, and by knowledge of other inlet systems, a conceptual model describing the medium-to long-term evolution of the inlet is presented. Key elements of the model are then examined with reference to field observations and to numerical simulations of tides, waves, sediments and morphology. Supported by historical evidence of inlet evolution in the Ría Formosa, the picture that emerges of inlet dynamics is essentially one of relative simplicity and predictability in the short-to medium-term

Support of subtidal tracer studies to quantify the complex morphodynamics of a river outlet: the Bevano, NE Italy.

Evolution of tidal inlets or river outlets has been widely described all over the world. However, most conceptual models are based on the long term perspective and field measurements to confirm these evolution schemes are scarce. The objective of the present study is to quantify the processes occurring at a small river outlet, the Bevano, during fair weather conditions. Subtidal fluorescent sand tracer method involving a new detection tool were used in the inlet and along the adjacent coast to assess sediment transport and bypassing processes. At the river mouth, sediment fluxes confirm an efficient bypass of sand through the inlet’s channel. However, this sediment transport is combined with migration processes of the channel (40 m in 2 months), and yields a self-alimentation of both updrift and downdrift coasts. As it has already been observed at small tidal inlets, migration of the Bevano river mouth results from the erosion of the downdrift coast, and readjustment of the cross-section by the longshore transport on the updrift coast. The detection device used for subtidal tracing has given encouraging results and will be improved in order to work in more dynamic environments

Sediment transport pattern and coastal evolution at lido di dante beach, Adriatic Sea

Inter-disciplinary medium term monitoring of a small coastal cell of the Northern Adriatic, Lido di Dante Beach, was undertaken starting from 2001. In association with the EU-CoastView Project, coastal state indicators were developed and surveyed. This paper presents the observations done during 3 years of surveys: beach morphodynamics, intertidal bars, dune morphology and vegetation, overwash observation and risk. Results evidence two areas with different dynamics: the Southern part of the beach is dependent on the Bevano River by-pass processes and all indicators are positive (stable vegetation, large beach) while the Northern part is very narrow, eroding (10m/year) and the dune is easily overwashed. This atypical behavior is though to be due to the groin that disturbs the protective function of the nearshore bar system. Copyright ASCE 2006