Coastal dunes: a nature-based solution to face coastal hazards

Nowadays, it is common to find degraded coastal fringes which require constant sand nourishments. Due to human direct interventions increasing erosion patterns or because of climate change, these critical coastal zones need innovative solutions to reduce the amount of nourished sand and increase the duration of this actions to reduce its maintenance costs. This work presents two nourishment alternatives compared to a standard homogeneous nourishment and a no action scenario for a coastal degraded beach. Xbeach numerical model has been used to study the different planned scenarios when considering an energetic storm for one of the Catalan endangered coastal fringes in the Ebro Delta. The results of deploying the nourished sand by forming a single dune or a field of mound dunes are compared to a no-intervention scenario and the classical homogeneous nourishment, obtaining a theoretical relevant reduction of eroded sand when nourishing the beach building a unique coastal dune. This study is a simple exercise, with no validation of the obtained results and the known limitations of the numerical model employed, but valuable to see that different shapes and volumes of nourished sand can importantly increase/alter the duration of the new sand being provided to a vulnerable coastal fringe.