As with all services provided, EBS aims to provide clients with the most accurate data possible with the latest technology available. Keeping with this goal, EBS recently acquired new hydrographic surveying equipment and software to upgrade the equipment used during depth surveys. The use of sonar to determine water depth is a simple technique but without proper experience on the surveyors’ end, it is easy to end up collecting poor or even inaccurate data. Factors such as the timing of data acquisition, the ability to monitor the data in real time, echo sounder ping rates, transducer frequency, and quality control measures were all taken into consideration by EBS when researching the best equipment and software to acquire. The result of that research was the purchase of a single beam echo sounder optimized for shallow water hydrographic surveying and a dual frequency transducer, along with the industry-leading hydrographic survey software package. By taking advantage of the new equipment and software, EBS is able to maximize the performance of the equipment, perform advanced data evaluations, and continue to provide our clients with high-quality deliverables.
To better explain some of the advantages of EBS’ new surveying equipment and software, it’s worth explaining the basics of what it all does. Essentially, the echo sounder transmits a single beam of sound via a transducer directly downwards then waits to receive an echo. An algorithm within the echo sounder correlates the interval between the sounding transmission and responding echo to the water depth.
The echo sounder itself is a unique piece of equipment that controls every aspect of the data collection process. Utilizing this particular echo sounder provides advantages over others due
to the features integrated into the unit, its ease of deployment, compactness, and the manufacturers’ overall focus on providing quality shallow water surveying equipment. Features integrated into the unit to optimize the results of shallow water surveying include a GNSS receiver in the unit, an ultra-precise timing mechanism to time stamp data and limit the potential for latency issues, a high ping rate allowing for the collection of a dense data set and to maximize bottom coverage, and the ability to operate using dual frequencies simultaneously.
In order to take advantage of the echo sounder’s ability to run dual frequencies, a dual frequency transducer is used. For shallow water surveying, the standard transducer operates at high frequency – 200kHz – due to the balance between depth resolution, penetration through water, and physical transducer size. While the high frequency is standard for shallow water surveying, utilizing a transducer capable of a low frequency (33kHz) simultaneously provides a valuable cross-check tool and the potential to view recently deposited sediment. In most cases, the depths derived from the low frequency will follow that of the high – providing a beneficial cross check of the high frequency without any additional effort. The second advantage of running a dual frequency survey comes up when suspended material is in high concentration, rendering the high frequency inaccurate, and when loosely deposited non-compact material is present, in which case the two data sets can be overlaid on top of each other to show potential sediment accumulation or the true depth to which dredging reached.
Combining equipment optimized for shallow water surveying with staff experienced in shallow water surveying provides our clients with accurate and detailed data along with a high level of confidence in the data quality.