Projects

Goal of the Project

This PhD research project investigates erosion caused by wave overtopping. Large-scale experiments will be conducted at Delft University of Technology using a newly designed wave overtopping simulator. These experiments will focus on understanding the hydraulic loading on the landward slope and within erosion pits. The primary goal is to better describe the hydraulic loading on the slope and to identify the factors that influence the progression of erosion pits. In the second phase of the research, efforts will be made to relate the insights gained about hydraulic loading to the erosion processes triggered by wave overtopping. This will be achieved by collecting existing data on erosion and analyzing and possible describing the observed erosion patterns using insights obtained from the large-scale experiments. Any newly discovered insights will be applied to case studies in The Netherlands to assess the impact of incorporating the clay layer in dike assessment, design, and maintenance.

Scientific Motivation

The required crest level of a dike is determined, among other factors, by the erosion resistance of the landward grass revetment. Currently, only the erosion resistance of the grass cover against wave overtopping is accounted for. The erosion resistance of the clay layer, often found beneath the grass cover, is typically neglected due to uncertainty in its erosion resistance. As a result, past calculations have been simplified by assuming that a dike breaches once the grass cover fails.

This research aims to improve the description of hydraulic loading on the landward slope. Additionally, it will be the first to investigate hydraulic loading within an erosion pit and the factors driving its progression. The insights from this PhD research will contribute to better estimating dike breach risks, enabling more optimized dike design and assessment.

Case Study

During my PhD research, we will develop new insights into the hydraulic loading caused by wave overtopping on the landward slope and within erosion pits, along with new findings on erosion pit progression. Any models developed during this study will be integrated, where possible, into the existing dike assessment and design framework (BOI) to showcase the impact of these findings. Case studies will be conducted on real dikes in the Netherlands, particularly in the province of Zeeland (near the coast) and along the Rhine, both of which are key areas of the Future FRM Tech research program.

Expected Outcomes

• Literature review on the erosion of the landward slope of a dike by wave overtopping.
• A research paper on the variation in characteristics of the flow caused by overtopping waves at the crest of a dike.
• A large-scale experimental setup to conduct experiments on wave overtopping using a newly designed wave overtopping simulator.
• A joint data paper with UCLouvain on field experiments with the wave overtopping simulator.
• A research paper on the development of the wave overtopping simulator, including a comparison of results from numerical modeling and large-scale experiments.
• A research paper on the quantification of hydraulic loading inside an erosion pit at a geometrical transition using large-scale experiments (at the toe/on the berm of a dike).
• A research paper on the progression of clay erosion during wave overtopping and its implications for the design and assessment of dikes on the erosion of the landward slope (GEKB).