In July 2021, an extraordinary precipitation led to severe flooding across Europe, particularly affecting South Limburg in the Netherlands, causing significant damage. In response, the Dutch government is seeking methods and new ways to mitigate the effects of future flash floods. Consequently, Waterschap Limburg (Limburg Water Board) initiated a physical experiment in Roermond in May 2023 to assess the effectiveness of movable flood protection barriers under various conditions. TU Delft, Flood Proof Holland, and AccessHub B.V. were involved in establishing a monitoring system that evaluated the stability and performance of these temporary flood barriers.

Although the experiment yielded success and Waterschap Limburg profitably selected appropriate temporary flood barriers to address flooding for the 2023-2024 festive season from Storm Pia, there remain knowledge gaps concerning these barriers. Limited documentation has left some aspects unclear, such as the fundamental physical processes and mechanisms of failure detection. This study aims to provide a thorough understanding of how to monitor physical changes through image processing and identify failure mechanisms by applying the horizontal stability equation.

Due to an extraordinary precipitation event in July 2021, the Dutch government want to utilise the temporary flood barriers to reduce the impact caused by a flash flood event in the future. As a result, Water Board Limburg, Flood Proof Holland and Delft University of Technology made an agreement to conduct a physical experiment in Roermond on May 2023 to test the functionality of the temporary flood barriers in different spatial conditions.

This report aims to provide a comprehensive understanding of the temporary flood barriers and their performance in spatial variability before the experiment. To achieve this, available information on various barriers has been summarised to make a valid argument for the comparison of different barriers.

The first part of this report provides an overview of worldwide available barriers with their corresponding physical concepts explained, while more detailed information is given on those tested in Flood Proof Holland. The report then presents a theoretical hypothesis based on the calculation of the resisting force of the barriers. The findings reveal that most of the tested barriers can withstand a water level of 50 cm on asphalt, concrete, sand, and grass. However, BoxBarrier and BoxWall(Waterschot) show exceptions when subpressure is taken into account.

The report also includes a comprehensive outline of a physical experiment that will be conducted in May 2023, which provides a detailed description of the experiment, as well as preliminary assessment criteria. These criteria include logistics, failure mechanisms, spatial conditions, and additional requirements from the water board, and will be used to assess the performance of the temporary flood barriers. Additionally, an ideal monitoring plan utilising video camera, tracer fluid, and RBR-Diver has been proposed for the experiment.

Lastly, the report features a discussion of a preliminary test conducted on February 15th 2023 in Flood Proof Holland, to evaluate the effectiveness of the designed monitoring approach. The test proved that the proposed monitoring plan was successful and emphasised the significance of proper equipment inspection, anchoring, and quality control of materials for the temporary flood barriers.

This research aims to improve the current knowledge and insight into the construction process, logistics, and construction costs associated with the offshore pumped storage hydropower plant. The main objective is to enhance the construction costs by optimizing the work method based on these sheltering effects.

The diffraction and sheltering effects due to the caisson dam will be determined using the Goda diffraction tables. Additionally, the Levelised Cost of Storage (LCOS) will be used to assess the cost-effectiveness of this bulk energy storage technology and enables the comparison with alternatives, such as lithium-ion and hydrogen storage.

In summary, this research addresses the promising potentials of work method optimization for offshore caisson projects regarding the local wave climate. For a case study in the North Sea, it has not only highlighted the relevance and importance of including wave sheltering. Moreover, with a LCOS of € 140-260/MWh it also shows the competitiveness of the offshore pumped storage hydropower concept once again. Alternative energy storage methods such as lithium-ion or hydrogen are in the range of € 200-400/MWh for lithium-ion and € 200-1900/MWh for hydrogen storage. Therefore, offshore pumped storage hydropower (PSH) can be a favorable solution enhancing the energy transition.