Experimental study of the development of scour at geotextile encapsulated sand systems = Etude expérimentale du développement d'affouillement sur des systèmes de géotextiles contenant du sable
das Neves, L. (2013). Experimental study of the development of scour at geotextile encapsulated sand systems = Etude expérimentale du développement d'affouillement sur des systèmes de géotextiles contenant du sable. On Course: PIANC E-Magazine 147: 13-26
In: On Course: PIANC E-Magazine. PIANC: Brussels, meer
Geosystems can be an interesting alternative to more traditional coastal defences in low-risk management areas. This paper presents an experimental effort to study scour development and more widespread beach lowering around sand-filled geosystems. Both passive (i.e. three dune erosion control systems with two configurations) and active (i.e. one nearshore submerged structure with four configurations) structures are investigated. A twodimensional physical movable-bed model simulating the prototype dune-beach system of Estela, located along the NW Portuguese coast, is employed in this study.
In the discussion of results five perspectives were considered: stability of geotextile encapsulated sand-systems under wave-loading; scour-depth development (scour holes development and scour-and-deposition patterns over the cross-shore length of the model); observations of erosion and backfilling during a test duration; dependency between scour-depth and the non-dimensional variables; storm response (changes in cross-shore beach-profile when exposed to storm conditions lasting for a test duration of 30 minutes); beach levels drawdown at the structure and more widespread beach lowering; recovery between storms (response to the changing forcing conditions); build up during swell conditions, followed by beach levels drawdown during storm conditions; volumetric changes due to seasonal variability; and coastal evolution: beach-profile change under persistent erosional conditions. As much as possible, the importance of relevant parameters to the hydrodynamic and morphodynamic outputs produced by each scheme and the characteristics of flow patterns during run-up and rundown phases is given throughout the discussion of experimental results. Finally, the extrapolation of the physical model results on the prototype is essayed.
The work presented in this paper is a summary of the PhD research of the author.
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