Sedimentation Management: Reservoir and Dam Dredging

Over time, natural erosion, watershed runoff, and environmental factors cause sediment to settle at the bottom of reservoirs and along dam structures. If left unmanaged, this buildup reduces usable water volume, restricts flow, and can damage mechanical systems.

Understanding sedimentation management through dredging requires examining:

1. What Is Reservoir Dredging?
2. What Is Dam Dredging?
3. What Is Sedimentation Management by Means Dredging?
4. What technologies are used in reservoir and dam dredging?
5. When Are Professional Dredging Services Necessary?

What Is Reservoir Dredging?

Reservoir dredging is the removal of dirt, silt, particles, and rubbish that accumulate at the bottom of a reservoir and take up space that water could otherwise use in  water management systems. Dredging equipment can remove or reduce this deposit to enhance storage capacity.

Reservoirs have long been used to provide sufficient quantities of water to large populations. They also serve as a habitat and food source for creatures that live in the region surrounding the reservoir, such as fish and frogs. While reservoirs are an important component of modern city water management, they are not flawless.

Reservoir performance can be affected by:

• Deforestation

• Pollution

• Natural erosion

These factors produce:

• Dirt

• Silt

• Particles

• Rubbish

This material accumulates at the bottom of the reservoir, reducing the space available for water storage.

Dredging equipment can remove or reduce this deposit, which might be natural or as a consequence of human action. As a result of the reservoir's expansion, its storage capacity may be enhanced.

What Is Dam Dredging?

Dam dredging is the removal of accumulated sand, silt, and debris from the bottom and edges of a dam to protect water storage capacity and maintain performance. It is used to eliminate sediment-related risks and prevent future issues.

Dams are an essential component of modern water management.

They may be utilized for:

• Hydroelectric generation

• Local agricultural needs

• Flood control

Sedimentation can accumulate along the bottom and edges of a dam, much like at reservoirs. This accumulation of, sand, silt and other debris limits the dam’s capacity for water storage and can cause harm to turbines and other components that make up the dam. Dredging is used to eliminate these risks to the dam's performance and prevent future issues.

What Is Sedimentation Management by Means of Dredging?

Dredging is a sediment management technique that may be utilized on a wide range of water bodies, but the specific characteristics and difficulties of many reservoirs and dams necessitate particular action. As a result, reservoir and dam dredging are not the same as other types of dredging.

Some main factors that make reservoir and dam dredging unique include:

• Reservoirs are generally found in rural areas, away from major industrial coastlines, where the bulk of dredging equipment is deployed.
• Reservoir access may be difficult in a few situations, notably if they are surrounded by steep-walled valleys or canyon settings.
• Reservoirs are frequently built in watershed regions that receive a lot of rain and erode naturally, resulting in sediments entering the water. Sediment is carried downstream until it piles up within the reservoir as erosion proceeds.
• Water levels in reservoirs built in deep valleys or canyons are almost always deeper, since much of the essential infrastructure is positioned near the impounding dam.
• Dams may accumulate sand and silt buildup at their bases and edges. This accumulation of sands, silts, and other debris limits the amount of water that can be stored in the dam.

The most important elements in determining whether dredging is the most suitable and cost-effective method include:

• The reservoir's location
• Volume and physical structure of the material to be removed
• Water depth
• Material types, and processing
• Transportation
• Ultimate disposal of dredged materials

 Careful evaluation of these elements helps determine the most effective dredging approach for each project. 

What Technologies Are Used In Reservoir and Dam Dredging?

Reservoir and dam dredging is carried out using a variety of well-known procedures and technologies. Dredging equipment and technique are divided into two categories: mechanical and hydraulic, although there are many variations on these themes that may be used depending on the reservoir's circumstances, and its built-up sediment.

What is Mechanical Dredging?

Mechanical dredging most commonly uses an excavator or crane with open digging or clamshell buckets to remove sediment.

The most common method is to use:

• An excavator

• A crane

• Open digging buckets

• Clamshell buckets

Mechanical diggers are installed on a flat deck barge or flexi-floats and pushed or pulled by a work boat to the required work areas, where they remove sediments and deposit them. Mechanical dredging may also be carried out by excavators working on land near the coast.

In certain circumstances:

• Water levels might be lowered for a short time
• Mechanical excavators may move straight onto the lake bed
•  Pressure reduction methods may be necessary to prevent sinking into soft material 

 Mechanical dredging is selected based on site conditions and the characteristics of the sediment being removed. 

What are the Benefits of Mechanical Dredging?

Mechanical dredging allows operators to remove harder materials with precision while maintaining control over sediment handling. It is effective for targeted excavation and grading. 

Benefits of mechanical dredging include:

• Can dig through harder materials, such as cobblestone or other masonry, with a clamshell bucket, excavator, standard-size backhoe, and the like
• Can dig and grade to a high degree of accuracy
• Sediment volumes on land are reduced, making management and storage easier
• Removes significant amounts of sediments at or near the in-situ state present at the bottom of reservoirs

Mechanical dredging is often selected when material conditions require strength, accuracy, and controlled excavation.

What is Hydraulic Dredging?

Hydraulic dredging is the transport of sediments in slurry form through temporary pipelines from the site of extraction to a designated repository area using dredging pumps.

Hydraulic dredging involves:

• Sediments mixed into slurry form
• Temporary pipelines
• Dredging pumps designed to handle high-viscosity fluids

Slurry pumps, which are essential in hydraulic dredging, are designed to handle high-viscosity fluids like slurries, making them a suitable fit for dredging operations. These pumps can efficiently move the slurry over long distances, ensuring smooth material transportation.

If pipeline transportation distance and or extra elevation difference lowers the discharge slurry velocity of the dredge pump below acceptable levels then boosters may be necessary to move the material.

Horizontal directional drilling (HDD) is increasingly becoming an essential tool for specialized dredging projects, particularly in areas where traditional dredging methods might not be feasible.

HDD can be used to:

• Drill under water bodies
• Install pipes for slurry transportation
• Access areas that are otherwise difficult to reach

By using HDD, dredging operations can be more precise and environmentally friendly, reducing the need for heavy equipment and minimizing disruption to surrounding areas. Hydraulic dredging is selected based on project conditions, transportation requirements, and site accessibility.

What are the Benefits of Hydraulic Dredging?

Hydraulic dredging allows material to be pumped directly from the point of dredging to the point of stockpiling or disposal, reducing handling requirements. It can also provide more efficient production rates when equipment, piping, and pumps are properly selected.

Benefits of hydraulic dredging include:

• Avoiding the need for double handling of material onto land by pumping directly from the point of dredging to the point of stockpiling or disposal
• More efficient production rates when equipment, piping, and pumps are properly selected than through mechanical dredging

Hydraulic dredging is often chosen when efficiency and direct material transport are priorities. Learn more about our hydraulic dredging capabilities. 

When Are Professional Dredging Services Necessary?

Professional dredging services are necessary when sediment buildup or debris begins affecting dam performance, water flow, or storage capacity. 

U.S Aqua is the leading provider of dam dredging services in the United States, and we’re ready to help your dam get back on track.

If your dam is still functional but just needs maintenance, we can:

• Clean out sediment buildup

• Clear away debris clogging water flow

• Restore performance without disrupting operations

No matter what kind of project you require done, give us a call today and see how quickly we can get started on it for you!

Related Articles

How Dredging Helps With Water Management - Here's more information on how dredging can help with water management.

References

Reservoir Dredging: A Practical Overview - https://www.westerndredging.org/phocadownload/Workgroups/Reservoir_Dredging/WEDA%20Technical%20Report%20-%20Practical%20Guide%20to%20Reservoir%20Dredging.pdf

About U.S. Aqua Services

U.S. Aqua Services was created to support the dredging process in advancing commerce and responding to its many challenges. To accomplish this, our dredging company assembled an exceptional group of experienced individuals and a diverse inventory of dredge equipment and excavator dredge pumps.

We offer dredging equipment rental services so you can have access to the latest and greatest in dredging technology without having to pay to maintain it, transport, and store it, along with dewatering services.

With an emphasis on mobility, dependability, durability, diversity, efficiency, and safety, our dredging rental company can ensure that our different types of dredging systems are easy to move through any terrain and can work in the most rugged and remote environments. Our multi-function hydraulic systems are built with jetting and mechanical options that can efficiently move loose sediment or stiff layers of clay.

US Aqua services also and maintains a ready fleet of Amphibious Marsh Equipment capable of completing projects in some of the harshest and most remote environments. U.S Aqua is also the dealer for Louisiana of the amphibious vehicle Fat Truck. No matter the size or scope of the job or the remoteness of your work location, you can rely on Fat Truck’s industrial off-road utility vehicles to get the job done right.