On the impact of a mega localized nourishment on the tidal currents.

Saulo Meirelles, Martijn Henriquez, Ad Reniers, Marcel Stive, Julie Pietrzak, Alejandro Souza, Alexander Horner-Devine

Chair(s): Mark van Koningsveld

Monday 29 june 2015

16:45 - 17:00h at Antarctica (level 0)

Themes: (T) Special session, (ST) Building with nature

Parallel session: 3D. Special session: Building with Nature

A 13-hours ADCP survey was carried out off the Zandmotor coast within the MegaPEX (Mega Perturbation EXperiment) framework. CTD profiles were also measured concurrently. The measurements covered 2 transects from -8 to -12 m depth: one offshore the tip of the nourishment and a second at its northern flank. The primary goal is to get detailed insights on the perturbation caused by the Zandmotor on the local hydrodynamics over a tidal cycle. Changes in the flow patterns intrinsically affect the sand transport pathways in the vicinity of the Zandmotor dictating its evolution. Apart from that, CTD profiles served to track the freshwater fronts ejected from the Rhine river that periodically hits the nourishment. Previous studies showed that the dynamics of the Region of Freshwater Influence (ROFI) also influences the local hydrodynamics adding more complexity regarding the sand mobility outside the surfzone. Preliminary results show a substantial flow acceleration at the tip of the mega perturbation followed by an apparent flow divergence at the northern flank during flood tide. In the presence of the ROFI, the flow direction seems to be changed specially in the cross-shore direction. Further analysis has been conducted together with a complementary dataset. The milestone of the present investigation is to better understand the middle shoreface disequilibrium caused by the Zandmotor.