Flow characteristics over coral reef

• Main Author: Ong, Kang Fu.
• Other Authors: Huang Zhenhua
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Civil engineering::Water resources
• Online Access: http://hdl.handle.net/10356/15838
• Institution: Nanyang Technological University

Understanding waves and the effects of its impact on coastal zones is essential to the design of coastal projects and the protection of the shoreline. In order to lessen the impact of the waves, and in turn minimizing the eroding nature of its force, coral reefs can be studied as they act as natural barriers in the shallow waters and help to protect the coastline from the waves. In general, there are three types of coral reef; fringing, barrier and atoll. The purpose of this project is to analyze the flow characteristics over coral reef. Linear wave theory is the elementary theory for wave analysis. Understanding the theory and how it affects wave setup and breaking would help in the investigation of the flow over coral reef. Experiments were conducted to measure the wave characteristics under different wave conditions. The raw data collected would then be plotted into graph and analyzed with respect to the elevation of mean water level, maximum elevation and the wave profile over coral reef to discover the resulting effect of coral reef acting on the flow. The analysis shows that wave break at similar location regardless of the presence of reef layers and wave breaking shifted further landward when depth increases. On further insights, wave breaking are independent of the reef layers and is dependent of the water depth. Wave setup increases with decreasing frequency, decreasing depth and increasing wave height. The presence of reef layer decreases setup due to the friction. Friction will reduce the energy of the wave. The surf zone would also be narrower and the reformed wave will travel a shorter distance of approximately 1 to 2m in the experiment. In other words, this would reduce the impact of wave to the shore. In summary, the reef layer would be desirable as it helps in reducing the wave setup and energy of wave reaching the shoreline through wave breaking and friction. To further validate the results, it is recommended to conduct an experiment of another depth to verify the proved relationship. In addition, further investigation on the reef layers porosity and drag coefficient are essential for advance studies on the effect of reef characteristics on wave motion.