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ABSTRACT In this study, the artificial opening of a new tidal inlet in an existing multiple inlet system is shown to significantly modify the adjacent nearshore and backbarrier morphology, as well as both updrift and downdrift shorelines. The study focuses on the dominant Faro-Olhão and Armona inlets in the Ria Formosa barrier island system of southern Portugal. The equilibrium state and future evolution of the system are inferred using a range of morphological and hydrodynamic indicators, including the evolution of the inlet cross-section, changes in tidal prism, and changes in the dimensions (length and area) of barrier islands. The results reveal how the morphology of an interconnected two-inlet bay system and the adjacent coastlines has evolved following the artificial opening and stabilization of Faro-Olhão inlet since 1929. A clear relationship between barrier island size, inlet cross-section/width, and tidal prism is demonstrated. Decadal time-scale changes in the tidal prism of the two interconnected inlets are shown to be the main mechanism responsible for morphological change, and have resulted in the remobilization of ebb-tidal delta sediments deposited during previous hydraulic configurations. These changes, in turn, have contributed to a narrowing of Armona inlet and an increase in the size of Culatra Island. The work highlights the importance of ebb-tidal deltas both as sand reservoirs and as conduits through which sand exchange between estuaries or lagoons and the open coast is regulated. It also shows the pivotal role of ebb-tidal deltas in trapping longshore-transported sediment and releasing it again during periods of increased wave activity. The findings have implications regarding the accurate assessment of the stability of multiple inlet systems. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Collocated detailed measurements of near-bed turbulent and intrawave flow are important for studying sediment transport processes and seabed evolution. Existing commercially available triple-axis profiling instruments do not provide collocated velocity measurements. To improve the capability to make such measurements a triple-axis coherent Doppler velocity profiler (CDVP) has been developed and tested in the marine environment. The instrument was designed to measure orthogonal velocity profiles within a narrow column of water at 16 Hz within 1 m of the bed with a vertical spatial resolution of 0.05 m. This paper describes the first deployment of the instrument, in a tidal inlet in Portugal during a multidisciplinary study, when CDVP flow velocity measurements were compared with data from other instrumentation. A pragmatic approach was adopted to assess the capability of the triple-axis CDVP, using both an evaluation of internal consistency and an assessment against two commercially available acoustic Doppler velocimeters (ADVs). Measurements of the mean and fluctuating velocity profiles were collected with the triple-axis CDVP, and these have been shown to be internally consistent and to be in good agreement with measurements obtained with the ADVs. [ABSTRACT FROM AUTHOR]