Estimates of the seasonal morphological evolution of the Barra Nova Inlet using video techniques

摘要

This contribution presents video data that are used to describe the seasonal morphological evolution of a highly dynamic coastal inlet system. The data were collected using an autonomous solar-powered video system that was deployed over a fourteen-month period at the Barra Nova Inlet, Algarve, Portugal. Both qualitative and quantitative analyses of the video data were undertaken using rectified plan view images and a time-stack technique respectively. The results of the qualitative analyses allowed the definition of modal states of the inlet morphology that are closely related to the forcing mechanisms of incident waves and tidal sea level change. Key inlet features and their characteristics under these modal states were also identified. Some of these inlet features were subsequently quantified using the time-stack technique, including inlet axis orientation and ebb delta width. The results presented here suggest that the morphology of the inlet system tends toward a dynamic equilibrium under extended periods of low incident wave (calm) conditions that are typical during the summer months. However, after one or more high-energy storm events, which typically occur in winter, the morphology of the inlet is altered rapidly and drastically. Thereafter follows a period of transition during which the inlet morphology tends to return to the pre-storm state. Thus, the morphology of the Barra Nova Inlet appears to undergo a seasonal cyclic behaviour that is closely linked to the incident wave conditions. (C) 2003 Elsevier Ltd. All rights reserved. [References: 18]