From light signals to sediment pathways : developing luminescence as a sediment tracing tool

The Netherlands has a long history of living with the sea, a challenge that is intensifying under climate change. The Wadden Sea, a UNESCO World Heritage site with unique ecosystems and landscapes, is particularly vulnerable. Protecting the coast while preserving this fragile environment requires understanding how sand moves along and across tidal channels and beaches. One common approach to keep up with (local) erosion is sand nourishment: adding sand to the coast and letting natural forces reshape the shoreline. Yet, how this added sand mixes with native sediments has remained largely unknown. This thesis introduces a novel method to trace sand movement using luminescence which is a property of sand grains that records their light exposure history. By measuring these luminescence signals in individual sand grains, it is possible to get insight into sediment pathways and dynamics in complex coastal environments. The method was developed by optimizing luminescence imaging techniques (EMCCD camera), performing field experiments to quantify the in-situ subaqueous bleaching of the luminescence signals and by applying the method to the Ameland Inlet in the Dutch Wadden Sea.