Tracking fluorescent tracer to monitor grain size-selective dispersion in subtidal zone: Patos Beach case study (NW Iberian Peninsula)

Abstract

Sediment tracer studies have become an increasingly used and improved technique. This approach allows to evaluate the sediment dispersion and track their pathways in a real marine environment. This type of study is essential to improve current coastal morphodynamic models since questions such as 'Where does the sand nourishment go?' are complex to answer, but essential for improving coastal management. The goal of this work is to analyze the behavior of fluorescent sediment tracers with heterometric grain size distributions in Patos Beach (Ria de Vigo, NW Spain). A field experiment was performed between 24th of September and 22nd of October 2018 with the injection of 200 kg of fluorescent tracer of native sediment in the subtidal zone. Oceanographic and topobathymetric data were acquired, and daily bed sediment samples were taken in order to observe tracer advection and dispersion. The results obtained on this beach allowed the establishment of selective sediment transport at two spatial scales: tracer transport towards the beach and tracer organization around bedforms. This research contributes to improve the current knowledge of sediment transport in a natural environment and its relationship with wave nonlinearities.