Sediment transport measurements with tracers in very low-energy beaches
Article first published online: 2 AUG 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Earth Surface Processes and Landforms
Volume 38, Issue 6, pages 561–569, May 2013
How to Cite
Carrasco, A. R., Ferreira, Ó., Matias, A., Freire, P., Bertin, X. and Dias, J. A. (2013), Sediment transport measurements with tracers in very low-energy beaches. Earth Surf. Process. Landforms, 38: 561–569. doi: 10.1002/esp.3300
- Issue published online: 18 APR 2013
- Article first published online: 2 AUG 2012
- Accepted manuscript online: 6 JUL 2012 02:55AM EST
- Manuscript Accepted: 28 JUN 2012
- Manuscript Revised: 15 JUN 2012
- Manuscript Received: 17 JAN 2012
- sediment transport;
- fluorescent tracer
This study investigates sediment transport at a very low-energy backbarrier beach in southern Portugal, from a spring-to-neap tide period, during fair-weather conditions. Rates and directions of transport were determined based on the application of fluorescent tracer techniques. Wind and currents were collected locally, whereas the dominant small and short-period wind waves were characterized using a morphodynamic modelling system coupling a circulation model, a spectral wave model, and a bottom evolution model, well validated over the study area.
For the recorded conditions sediment transport was small and ebb oriented, with daily transport rates below 0.02 m3 day-1. Tidal currents (mainly ebb velocities) were found to be the main causative forcing controlling sediment displacements. Transport rates were higher during spring tides, tending towards very small values at neap tides. Results herein reported points towards the distinction between tracer advection and tracer dispersion in this type of environment. Transport by advection was low as a consequence of the prevailing hydrodynamic conditions (Hs < 0.1 m, and max. current velocity of 0.5 m s-1) and the tracer adjustment to the transport layer, whereas dispersion was relatively high (few metres per day). Tracer techniques allowed distinguishing the broad picture of transport, but revealed the need for refinement in this type of environments (bi-directional forcing by ebb and flood cycles). Copyright © 2012 John Wiley & Sons, Ltd.