Survey 101: Hydrographic Surveys

Hydrographic surveying stands as a pivotal tool in the arsenal of marine professionals. At Subsea Marine Services, we pride ourselves on being at the forefront of the offshore survey market. Our operations encompass a wide range of activities, from laying marine fiber optic cables to conducting comprehensive survey services. This blog aims to provide a broad overview of hydrographic surveys and highlight their importance in marine operations.

What is Hydrographic Surveying?

Hydrographic surveying is the science of measurement and description of features which affect maritime navigation, marine construction, dredging, offshore oil exploration/drilling and related activities. It involves the collection of data regarding the physical features of the ocean, seas, coastal areas, lakes, and rivers.

This type of surveying is crucial for creating nautical charts, ensuring safe navigation, aiding in coastal management, and supporting marine infrastructure projects. The process includes the measurement of water depth (bathymetry), the study of the morphology of the seabed, and the analysis of tide and current information.

Importance in the Marine Industry

1. Navigation Safety: Hydrographic surveys are essential for creating accurate nautical charts, which are vital for the safe navigation of ships and other vessels. These charts provide crucial information about water depths, hazards, and other features necessary for safe passage.

2. Marine Construction: For any construction project in marine environments, such as bridges, ports, and offshore wind farms, hydrographic surveys provide the necessary data to design and build safely and efficiently.

3. Resource Exploration and Management: The oil and gas industry, as well as the burgeoning field of seabed mining, rely on hydrographic surveys for exploration and environmental monitoring.

4. Environmental Protection and Coastal Management: These surveys help in understanding the marine environment, monitoring changes due to natural or human activities, and aiding in coastal defense and habitat restoration projects.

5. Laying of Subsea Cables: The laying of marine fiber optic cables, a specialty of Subsea Marine Services, requires detailed knowledge of the seabed to avoid hazards and ensure the longevity and integrity of the cables.

Techniques and Technologies

Echo Sounders and Multibeam Sonar Systems

Echo sounders are the most common tool for measuring water depth. They work by sending a sound pulse (ping) directly downwards and measuring the time it takes for the echo to return from the seabed. Multibeam sonar systems, on the other hand, use multiple beams to cover a wider area and create a detailed map of the seabed.

Side-Scan Sonar

Side-scan sonar is used to create detailed images of the seabed. It is especially useful for identifying objects and features on the ocean floor, which is crucial for cable route surveys and identifying potential hazards.

Sub-bottom Profilers

Sub-bottom profilers are used to image the layers of sediment or rock under the seabed. This is important for understanding the geological environment, especially for anchoring structures or laying cables.

GPS and Positioning Systems

Accurate positioning is critical in hydrographic surveying. GPS and other positioning systems ensure that the data collected is precisely located in geographical space.

Autonomous and Remotely Operated Vehicles

Unmanned vehicles, such as Autonomous Underwater Vehicles (AUVs) and Remotely Operated Vehicles (ROVs), are increasingly used for hydrographic surveys. They can reach areas that are difficult or dangerous for human divers and can operate in extreme depths.

The Process of Hydrographic Surveying

Planning and Preparation

A successful hydrographic survey starts with meticulous planning. This includes defining the objectives, selecting the appropriate survey methods and tools, and understanding the environmental conditions of the survey area.

Data Collection

Specialized service vessels such as our own R/V Echo are equipped with the necessary tools are deployed to the survey area. Data is collected as per the predefined plan, ensuring comprehensive coverage and accuracy.

Data Processing and Analysis

The raw data collected is processed to remove errors and noise. It is then analyzed to create useful information like bathymetric maps, seabed composition maps, and other relevant data sets.

Charting and Reporting

The final step is the creation of nautical charts or other reports as required by the project. This information can then be used for navigation, planning, construction, or other purposes.

Challenges and Future Directions

Hydrographic surveying faces various challenges, including dealing with harsh marine environments, deep-water surveying, and the constant evolution of technology.

Conclusion

Subsea Marine Services remains committed to advancing the field of hydrographic surveying. Our expertise and technology enable us to provide unparalleled service in this essential domain of marine operations. Through this blog, we aim to share our knowledge and passion for the offshore market, contributing to safer, more efficient, and environmentally sustainable marine activities.