E. Brand¹*, S. Poortman¹ , Q. Lodder^1,2, E. Zandt¹

¹ Rijkswaterstaat, Nederland; ² TUDelft, Nederland

^* Corresponding author: evelien.brand@rws.nl

Introduction

The Netherlands has a long-standing practice of coastline maintenance using sand nourishments. Valuable knowledge is gained from large-scale pilots, such as the Sand Motor and the ebb-tidal delta nourishment at Ameland. Furthermore, decades of experience have resulted in valuable insights, leading to a continuous evolution of the nourishment strategy. The nourishment approach has become increasingly large‑scale, the range of nourishment types has expanded, and designs have been refined to better match local coastal conditions (Brand et al., 2022). Optimization of the nourishment approach and designs remains ongoing. Coastal monitoring, data analysis, and modelling contribute to this process. Here, we illustrate how recent advances in coastal research have directly influenced and improved the Dutch nourishment program.

Objective and Methods

Modelling: Numerical modelling is particularly valuable for predicting sediment pathways, especially in complex morphodynamic environments. Model studies have been conducted for Southwest Texel (Elias et al., 2021) and the tidal inlet between Vlieland and Terschelling (De Wilde and Elias, 2023), for example, providing insight into the expected distribution of nourished sediment. Modelling is also applied to assess potential risks. For the combined beach and channel‑wall nourishment at Noord‑Beveland the impact on the flow patterns in the adjacent channel was studied (Quataert et al., 2024), while the upcoming shoreface nourishment at Scheveningen was modelled to assess the possibility of unintended sedimentation in the harbor (Quataert et al., 2021).

Monitoring and data analysis: we also monitor and analyze the data to learn from nourishments. The recent shoreface nourishment at Ameland is closely monitored within the Source project to improve the understanding of morphodynamics and ecological impact of shoreface nourishments (Source, 2025). A large monitoring campaign is also executed at the Vlakte van de Raan ebb‑tidal delta nourishment to study sediment transport pathways and ecological impact (de Haan et al., 2023). Additional monitoring is being conducted at the earlier mentioned nourishments at Noord‑Beveland and Texel southwest to capture the evolution of these nourishments.

Results

Together, these studies have led to several notable adjustments in the nourishment strategy and design, including:

• Large‑scale beach nourishment at Texel southwest (planned 2027–2028): The nourishment volume is triple the standard practice to test whether a more extensive intervention offers a cost‑effective way of maintaining the coastline. Model studies played an important role in anticipating its effects.
• Building out the coast at Noord‑Beveland (end of 2025): Modelling and analysis of earlier interventions provided confidence to proceed with this significant adaptation, aimed at supporting long‑term coastline maintenance. Its evolution will be closely monitored.
• Introduction of shoreface nourishments at new locations: Shoreface nourishments at Domburg and Scheveningen have been added to the nourishment program based on the hypothesis that they contribute to coastline maintenance.
• Assessment of ebb‑tidal delta nourishments: Ongoing work evaluates both the potential benefits and environmental impacts of nourishments at the Vlakte van de Raan and Terschelling.
• Improved designs of nourishments near notches in the dunes: Through monitoring we have improved our understanding of the relationship between nourishment design and aeolian transport (Coumou, 2025).

A persistent challenge is the assessment of cost‑effectiveness of innovative designs. Predicting the lifespan of individual interventions is often complex and uncertain.

Large-scale nourishment at Southwest Texel (planned)

References

Brand, E., Ramaekers, G., Lodder, Q., 2022. Dutch experience with sand nourishments for dynamic coastline conservation – an operational overview. Ocean Coast Manag. 217, 1–17.

Coumou, L., 2025. Korrelgrootte en beach armouring strandsuppletie Vlieland 2023. Arcadis rapport WASE5H3JW77F-350239261-7029

De Haan, E., de Vos, L., Kruijt, D.B., 2023. T0 Aanvullend Onderzoek Vlakte van de Raan. Resultaten macrozoöbenthos- en sedimentanalyses 2023. Rapportnr. 23-494. Waardenburg Ecology, Culemborg

De Wilde, T., Elias, E., 2023. Morfologische analyse systeemsuppletie Terschelling (Zeegat van het Vlie). Deltares rapport 11209263-004-ZKS-0007

Elias, E., Roelvink, F., Pearson, S., 2021. Systeemsuppleties op Eilandkoppen. Deltares rapport 11205236-005-ZKS-0003

Source, 2025. https://source-research.nl/news/media/from-design-to-realization-experimental-shoreface-nourishment-at-ameland-oost/

Quataert, E., Elias, E., de Wilde, T., 2021. Regionaal advies: vooroeversuppletie Scheveningen. Deltares rapport 11206794-001-ZKS-0006

Quataert, E., Elias, E., de Wilde, T., 2024. Regionaal Advies: Strand-geulwandsuppletie Noord-Beveland. Deltares rapport 11209263-001-ZKS-0002