The forces of nature wreak havoc on coastlines. As the frequency of these events rises, coastal communities worry about their future. Environmentalists, government officials, and community leaders turn to the dredging industry to protect their shrinking coastlines, as well as the ecosystems and communities surrounding them.
Dredging is the process of removing material from the bottom of a water environment. During the process, the material is first loosened at the bottom of the surface, then removed by suction or mechanical means. Once removed, it is transported and disposed of or used for another purpose. When protecting coastal environments, the dredged material is usually sand. Often, this sand is relocated and used to build barriers to protect coastlines from natural erosion.
At first glance, removing sand from the ocean floor may not seem helpful to the environment. However, the U.S. Army Corps of Engineers and the dredging industry have worked hard to develop techniques that protect all entities affected by the dredging process, including the delicate handling of natural environments along the coastline.
Why coastal areas need dredging
Coastal areas experience subtle environmental changes daily from the ebb and flow of coastal activity. The benefits of coastal living are also the causes of coastal erosion.
Major causes of coastal erosion:
- Waves: caused by ocean currents and tides changing the ocean floor, erode the coastline
- Wind: moving sand to create and destroy dunes
- Ice: particularly when thawing and drifting into the shore
- Sediment Transport: known as littoral drift, moves sediment and deposits it elsewhere
- Tides and Currents: fuel waves and littoral drift, shifting material on and offshore.
Strong storms only increase the amount of erosion along the coast, producing high winds, storm surges, and rising ocean levels.
Solutions to erosion
As the beaches continue to erode, communities seek solutions to protect their treasured coastlines. Soft sea defenses create barriers to erosion by adding sand in areas where extensive erosion from water, wind, and storms exist. Building soft sea defenses requires dredging to remove sand from the ocean floor and relocating it to build soft engineering solutions such as:
- Replenishing beaches
- Creating and enhancing dunes
- Reinforcing barrier islands
- Creating offshore bars
Along the storm-battered coast of Louisiana, a major restoration and coastal protection project with soft engineering solutions used dredging to mine for sediment offshore and relocate it to protect and replenish eroding shorelines and marshes. The beaches, barrier islands, and wetlands needed enrichment to protect against storm surge and flooding, reduce land loss from rising sea levels, and support the natural habitats of millions of migratory birds and aquatic species dependent on the marshes and barrier islands of Louisiana. Over 44 million cubic yards of dredged material restored critical marsh habitat and barrier islands.
Natural barriers to erosion
The delicate balance of various coastal ecosystems needs careful consideration and planning to best preserve the coastline and protect fragile ecosystems. Many coastal ecosystems function as natural barriers against storm damage and erosion. Along the coast, sandy beaches and wetlands protect against flooding and erosion, while coral reefs and mangroves defend against waves and storm damage. Mangroves provide the added benefit of binding and building soil to prevent damage and erosion. Because coastal communities benefit from the natural protections these ecosystems provide, they must be preserved and protected.
Dredging projects to prevent flooding and storm damage must also protect the ecosystems.
Moving sand to foreshore locations protects the coastline, but careful planning and implementation must take into consideration the ecosystem. For instance, when dredging near mangroves, the timing of the work and control of turbidity is essential to prevent too much sediment from entering the shallow waters of the mangrove. The same is true near coral reefs where turbidity is of concern, and specialized equipment must operate within certain seasonal windows to prevent sediment particles from harming the coral. The dredging industry is highly regulated, and protections exist to ensure natural barriers remain safe when dredging nearby.
Dredging near coastal communities
Every dredging project must start with a detailed plan. When choosing the appropriate dredger, consider soil conditions, location, transport options, and eventual placement of dredged materials. Several types of dredgers work well in the sand, but dredging location and access by equipment, such as barges needed for transport, affect the choice of dredgers used. Logistically, there are many factors to consider when planning a dredging project.
Depco Power Systems powers dredging
Depco buys and sells marine engines, generators, gears, and transmissions required to power the dredging industry. Depco understands the needs of the dredging industry and can fit your dredging system with the power your dredges, ships, and pumps need to get the job done. Call a member of our knowledgeable sales team today to outfit your next dredging project.
