As a company that specializes in surveys which includes bathymetric surveys, we were contracted by a client for a project in Eleko, Lagos.

The goal was clear: to deliver an accurate and unbiased assessment of the volume of sand our client had dredged. Carrying out a bathymetric survey isn’t just a routine job for us, it’s an opportunity to showcase the value of precise data and help our clients make better, evidence-based decisions.

Our client wanted to know exactly how much material they had dredged. This was important for their records and for making sure their work matched the rules set by regulators. We were there to offer a fair, unbiased measurement they could trust.

A 5 man crew was sent to the site with a single beam echosounder and GNSS

Our survey team used special sonar equipment, single-beam echo sounder. Think of sonar as a way of “seeing” underwater by sending out sound waves and measuring how they bounce back. We did two surveys: one before dredging began and another after it was finished. By comparing these two maps, we could spot the real changes on the riverbed.

How We Processed the Data

We paid a lot of attention to making sure our data was clear and correct. Here’s what we did, in everyday terms: We lined up the “before” and “after” data so they matched perfectly

We tweaked the depth readings to allow for changes in tide and water levels

We cleaned up the information to take out anything that didn’t belong,like random noise or errors

How We Calculated the Volume

After cleaning up the data, we used computer software made for this kind of work. By looking at the difference between the two underwater maps, we got a solid estimate of how many cubic meters of material were actually removed. This gave our client a number they could use for official reports and planning.

We didn’t just hand over numbers, we explained our methods and gave our client clear diagrams and summaries. With this report, they could show regulators that everything was done by the book, keep their company records up to date, and feel confident about the work completed.

Doing the Eleko survey showed how much careful surveying and clear communication matter. We see every job as a way to give our clients trustworthy answers, using simple steps, honest data, and plain language.

Bathymetric Survey at Eleko

Bathymetric Survey at Eleko