Pilot Sand Groynes Delfland Coast: Efficiency and practical feasibility of a pulse nourishment

In September and October of the year 2009, three sandgroyne nourishments have been executed at the Delfland Coast near the village of Ter Heijde. The nourishments have been executed to restore the sediment buffer in the upper part of the coastal profile. A sandgroyne is a concentrated amount of sediment (200.000m3) artificially nourished from the beach into the sea, appearing in the formation of peninsulas. It was anticipated that the three sandgroynes would be absorbed into the coastal system by the impact of waves and currents, nourishing the upper shoreface from the shoreline until a depth of about -5m NAP over a coastal stretch of about 2.5km. The construction and evolution of the sandgroynes have been monitored intensively. The following research objectives were proposed: 1) Assess the morphological evolution and practical aspects of the sandgroynes constructed at the Ter Heijde coast and 2) Use the site specific knowledge from the Ter Heijde pilot project to create a future perspective of sandgroyne nourishments as a common applied method to nourish the shoreface. This master thesis describes the process of the monitoring campaign, the results of a morhpological data analysis, the results of an initial model simulation set-up and a practical analysis. The sandgroynes have been absorbed in the coastal system, dominantly between the shoreline and the -5m depth contour. However the spatial scale of longshore sediment redistribution was larger than accounted for, driven by the intense wave climate. It is concluded that the sandgroynes can be an effective method for nourishing the shoreface, under flexible contract requirements that acknowledge the dynamics of the natural system.Hydraulic EngineeringCivil Engineering and Geoscience