Why is it called a pier?
The definition and purpose of a dock
A jetty is a structure that extends from the shoreline into a body of water, typically an ocean or river. It is designed to control the flow of water and sediment and provide protection to the shoreline, harbor, or riverbank. Jetties are commonly found in coastal areas and serve a variety of purposes, including navigational aids, erosion control, and harbor management. But where does the term “jetty” come from and why is it called a jetty?
Etymology of the word “jetty
The word “jetty” has its roots in the French language and is derived from the French word “jetée”, which means “projecting structure” or “pier”. The term was introduced into the English language in the 15th century and has since been widely used to describe a variety of coastal structures. The etymology of the word suggests that a jetty “juts out” into the water, projecting beyond the shoreline.
Historical significance of jetties
Jetties have been used for centuries and have a rich historical significance. In ancient times, civilizations such as the Egyptians, Greeks and Romans built jetties to facilitate maritime trade and protect their ports. These early jetties were often constructed of wood, stone or a combination of both. Over time, the construction techniques and materials used to build jetties have advanced significantly, allowing for more resilient and effective structures.
Functions and benefits of docks
One of the primary purposes of jetties is to provide a navigational aid for vessels entering and leaving harbors or river mouths. Jetties help create a defined channel that directs the flow of water and guides ships safely into the harbor. By stabilizing the entrance, jetties prevent the accumulation of sand and sediment, ensuring a clear and accessible path for vessels.
Coastal erosion is a natural process that can be exacerbated by human activities. Jetties play a critical role in mitigating erosion by interrupting the longshore drift of sand and sediment along the shoreline. They act as a barrier, trapping sediment and preventing it from being carried away by currents. This helps maintain the beach profile and protects the adjacent shoreline from erosion.
Types of jetties
Perpendicular jetties, also known as groin jetties, are constructed at right angles to the shoreline. They are typically built in pairs, extending from the shore and meeting at a point offshore. These groins are effective at trapping sediment and preventing it from moving along the shore. They are commonly found in areas with significant sediment transport and are often used to maintain navigable channels in harbors.
Parallel jetties, as the name implies, run parallel to the shoreline. They are typically longer than perpendicular jetties and are used to stabilize and protect beaches. By creating a barrier to longshore drift, parallel jetties help maintain the supply of sand to the beach, reducing erosion and preserving the recreational value of coastal areas.
Modern jetty construction techniques
Piling and sheet piling
Modern jetty construction often involves the use of piles, which are long cylindrical structures driven into the seabed or riverbed. Piles provide structural support and stability to the jetty. Sheet pile jetties, on the other hand, use interlocking steel or concrete sheets that are driven into the ground to form a continuous wall. These techniques provide durability and resistance to water and weather conditions.
Rock Pile Jetties
Rock armor jetties are constructed using large boulders or rocks. The rocks are carefully placed and stacked to create a stable structure that can withstand the forces of waves and currents. The voids between the rocks allow water to pass through, reducing the impact of wave energy and preventing erosion. Rock armor jetties are particularly effective in areas with high wave energy and have a long lifespan.
Jetties play an important role in coastal and harbor management, providing navigation aids and erosion control. The term “jetty” originated in the French language to describe a projecting structure that extends into the water. Over time, jetties have evolved in design and construction techniques, incorporating modern materials and engineering practices. Understanding the functions and benefits of jetties helps us appreciate their importance in maintaining a safe and sustainable coastal environment.
Why is it called a jetty?
The term “jetty” originated from the French word “jetée,” which means “a projecting structure.” It is believed to have been derived from the Old French term “jeter,” which means “to throw” or “to project.” The name “jetty” was given to this type of structure because it extends outward into the water, similar to how a projectile is thrown or projected.
What is the purpose of a jetty?
A jetty is typically built to protect a shoreline or harbor from the forces of waves and currents. Its primary purpose is to create a barrier that reduces the impact of waves and prevents sediment from entering a harbor or channel. Jetty structures also help to maintain navigable waterways by controlling the flow of sediment and preventing the buildup of sand or silt.
How is a jetty constructed?
A jetty is constructed by driving long piles or columns into the seabed or riverbed. These piles provide a foundation for the jetty and ensure its stability. The structure is then built on top of the piles using various materials such as rocks, concrete, or steel. The design of the jetty takes into account factors such as wave energy, water depth, and sediment transport to ensure its effectiveness in protecting the shoreline or harbor.
What are the different types of jetties?
There are several types of jetties, including:
- Perpendicular or T-head jetties: These jetties extend perpendicular to the shoreline and are often used to create a protected harbor entrance.
- Parallel jetties: These jetties run parallel to the shoreline and are designed to trap sediment and maintain a navigable channel.
- Detached breakwaters: These jetties are separate structures located offshore and are used to protect a harbor or shoreline from wave action.
- Revetted jetties: These jetties are built using revetments, which are sloping structures made of rocks or concrete. They help dissipate wave energy and prevent erosion.
Are jetties only used in coastal areas?
No, jetties are not limited to coastal areas. While they are commonly used along coastlines to protect harbors and shorelines from erosion and sedimentation, they can also be found in river systems and inland waterways. In these cases, jetties are often used to maintain navigable channels, control sediment transport, and prevent riverbank erosion.