Coastal Engineering - Sri Lanka

07/04/2023

Site Visit to Gandara Fishery Harbour

07/03/2023

Offshore Breakwaters: Protecting Coastal Environments

Offshore breakwaters are structures built offshore to reduce the impact of waves on the shoreline. They are designed to reduce wave height, wave energy, and wave-induced erosion. These structures have several applications, including protecting coastal infrastructure, enhancing beach environments, and facilitating navigation.

Applications of Offshore Breakwaters

One of the primary applications of offshore breakwaters is to protect coastal infrastructure such as harbors and marinas. Waves can cause significant damage to boats and docks, resulting in costly repairs and downtime. Offshore breakwaters can reduce wave energy and protect these structures, providing a safe haven for boats and improving the efficiency of port operations.

Another application of offshore breakwaters is to enhance beach environments. Waves can cause beach erosion, leading to a loss of recreational space and economic value. Offshore breakwaters can reduce wave energy and promote sand accumulation, creating wider beaches and more stable shorelines. This can attract more tourists, boost local economies, and provide greater protection for coastal communities.

Finally, offshore breakwaters can facilitate navigation by reducing the impact of waves on ships. Waves can make navigation difficult and dangerous, particularly in shallow water. Offshore breakwaters can reduce wave height and create calmer waters, making it easier and safer for ships to navigate close to shore.

Design Principles of Offshore Breakwaters

The design of offshore breakwaters depends on several factors, including the wave climate, seabed conditions, and the desired level of protection. The following are some of the key design principles of offshore breakwaters:

Height and Length: The height and length of the breakwater must be designed to match the wave conditions at the site. The breakwater must be tall enough to reduce wave height and long enough to reduce wave energy.
Orientation: The orientation of the breakwater must be designed to align with the prevailing wave direction. This ensures that the breakwater is effective in reducing wave energy and protecting the shoreline.
Shape: The shape of the breakwater can vary, depending on the wave conditions and the desired level of protection. Common shapes include rubble mounds, submerged reefs, and floating breakwaters.
Material: The material used to construct the breakwater must be durable and resistant to wave action. Common materials include concrete, rock, and steel.
Environmental Impact: The design of the breakwater must take into account the potential environmental impact, including changes to wave patterns, sediment transport, and marine habitats. The breakwater should be designed to minimize any adverse effects on the environment.
In conclusion, offshore breakwaters are effective structures that can protect coastal infrastructure, enhance beach environments, and facilitate navigation. The design of offshore breakwaters depends on several factors, including the wave climate, seabed conditions, and the desired level of protection. By following the key design principles, engineers can design and construct effective offshore breakwaters that provide long-lasting protection to coastal communities.

06/03/2023

Linear Wave Theory: Understanding the Behavior of Ocean Waves

The study of ocean waves is a critical component of coastal engineering and marine science. Understanding the behavior of waves is essential for designing coastal structures, predicting beach erosion, and assessing the risks associated with coastal hazards. Linear wave theory is a mathematical framework that is commonly used to study the behavior of ocean waves. In this article, we will explore the basics of linear wave theory and its applications in coastal engineering.

Linear wave theory is a simplified mathematical model that describes the behavior of ocean waves based on a few key assumptions. The theory assumes that the waves are small relative to the depth of the water, and that the water particles move in simple harmonic motion. The theory also assumes that the wave speed is constant and that the wave amplitude and frequency are independent of each other. These assumptions allow us to model the behavior of ocean waves using linear equations.

One of the most important concepts in linear wave theory is wave dispersion. Dispersion refers to the phenomenon in which waves of different wavelengths travel at different speeds. This is due to the interaction between the waves and the water particles, which can cause longer waves to travel faster than shorter waves. This can have significant impacts on the behavior of ocean waves, such as causing wave breaking and altering the propagation of wave energy.

Another key concept in linear wave theory is wave refraction. Wave refraction occurs when waves encounter a change in the shape of the sea floor or coastline. The interaction between the waves and the sea floor can cause the wave direction and energy to change, leading to changes in wave height and direction along the coast.

Linear wave theory has many practical applications in coastal engineering. Engineers use the theory to design coastal structures such as breakwaters, jetties, and seawalls, which are designed to protect coastal communities from the impacts of waves and coastal erosion. Understanding wave behavior is also important for predicting beach erosion and for assessing the risks associated with coastal hazards such as storm surges and tsunamis.

In conclusion, linear wave theory is a powerful tool for understanding the behavior of ocean waves. It allows us to make predictions about wave behavior and to design coastal structures that can protect our communities and natural resources. As our understanding of wave behavior continues to evolve, linear wave theory will remain a critical component of coastal engineering and marine science.

References:

Dean, R. G., & Dalrymple, R. A. (2002). Water wave mechanics for engineers and scientists. World Scientific.

Holthuijsen, L. H. (2007). Waves in oceanic and coastal waters. Cambridge University Press.

Mase, H., & Matsuoka, Y. (2012). Applied marine hydrodynamics. CRC press.

03/03/2023

Offshore borehole investigation

01/03/2023

21/02/2023

Breakwater construction with barges (Colombo South Port)

05/02/2023

Rough Sea ....

13/09/2022

Fundamental Bench mark at Pothuvil