Dredging projects require reliable bathymetric data to support planning, execution, and verification of underwater excavation works. Surveys are typically performed before dredging to establish baseline depths and volumes, and after dredging to confirm achieved depths and compliance with project requirements.
Accurate bathymetric monitoring throughout the dredging lifecycle is essential for volume calculations, contractor verification, and the preparation of as-built documentation.
Both annual condition assessments and pre-dredge inspections require hydrographic surveys to evaluate the current state of the dredging area. These surveys are typically compared with as-built surveys conducted after construction projects (in the case of artificial ponds) or with the results of previous post-dredge surveys.
Post-dredge surveys are conducted usually 2 days after dredging to verify that the result has met the contract requirements and to determine if any additional work is needed.
These surveys form the basis for project acceptance and the creation of as-built drawings.
Fig.1 - Sections of Dredging Works
The drone-based echo sounding system is applied throughout the dredging workflow by asset owners, contractors, and survey service providers to support planning, monitoring, and verification activities.
Tasks
Plan and monitor dredging activities, and verify contractor-reported volumes.
Benefits
Achieve faster and cost-effective contractor verification compared to traditional boat-based sensor methods. UAV systems may be up to 2 times more cost-efficient than a standard approach using a ship, a boat, or an USV.
Tasks
Plan dredging work volumes and provide detailed customer reporting.
Benefits
Utilize precise echo sounding data for accurate work volume estimation and comprehensive reporting to clients, improving operational efficiency and transparency.
Tasks
Incorporate pre and post-dredging monitoring surveys into service offerings.
Benefits
Leverage existing enterprise drone fleets without additional UAV purchases, enhancing service versatility of existing drone operations. The total cost for pre and post monitoring could range from $2'000 to $20'000 or more, depending on the specifics of the project.
The solutions at SPH Engineering include single and dual-frequency SBES systems for effective dredging monitoring. We offer three types of SBES echo sounders and one MBES system depending on survey requirements, such as water depth, sediment conditions, and area accessibility. With sensors from EofE Ultrasonics Ltd. (SBES) or Cerulean Sonar (MBES), our UAV-borne systems deliver precise results.
UAV-based echo sounding provides an effective alternative to the traditional methods of bathymetric surveys in projects where access, safety, or operational constraints limit the efficiency of vessel-based methods.
Hard-to-reach areas
Echo sounders on drones can access areas that are difficult or impossible to reach with traditional surveying methods, such as dense seaweed or complicated water access.
Multiple surveys of small ponds, lakes, or trenches
Drones equipped with echo sounders can efficiently conduct multiple surveys of smaller bodies of water, providing detailed and accurate data.
Cost Savings
Drones can significantly reduce the costs associated with traditional survey methods, such as using ships with the same echo sounder sensors.
This is especially true for smaller bodies of water or areas with limited access.
Accuracy
The accuracy of drone-mounted systems is the same as for manned and unmanned boats.
Enhanced Safety
Drones can remove the human element from harm’s way during initial inspections after a major failure of equipment, such as barges or cranes, reducing the risk of injury.
