CEE ECHO™ for very shallow surveys in the San Elijo Lagoon Restoration

About the project

Since 2017, Coastal Frontiers Corporation (Moorpark, CA, USA) has provided lagoon and nearshore data collection services to San Diego’s habitat restoration non-profit Nature Collective and project contractor Moffatt and Nichol, as part of the San Elijo Lagoon Restoration Project (SELRP) in Cardiff-by-the-Sea.

SELRP is one of the most extensive wetland restoration projects in California, and the ecosystem features a number of very shallow channels and lagoons. The lagoon channels and adjacent uplands were dredged and graded to improve tidal flushing and water quality. In addition, 450,000 cubic yards of beach quality sediment was beneficially reused as beach nourishment in Cardiff and Solana Beach.

The challenge

Bathymetry surveys were required to establish the pre and post construction conditions, in addition to progress surveys and ongoing monitoring. Owing to the extremely shallow water, with survey depths typically under 4 ft (1.2 m), echo sounder selection was a critical factor in a successful outcome. The echo sounder had to work when the boat was barely floating above the bottom.

The solution

Coastal Frontiers used the project to replace its previous echo sounder with the CEE ECHO™. Deployed on a small manned boat or the CEE-USV™ in combination with HYPACK software, the CEE ECHO™ received RTK GNSS position data from a Hemisphere S320 rover.

Chris Scott of Coastal Frontiers comments on the new equipment benefits:

“The auto-gain and -sensitivity vastly improved the time required to both collect and process our single-beam data. In addition, the CEE ECHO’s small form-factor allowed us to reduce deck space needed for our gear and eliminate about 20 lbs of batteries required for our old echosounder!”

Chris Scott, Coastal Frontiers

Surveying in active dredging

As specialists in this type of multiple technique nearshore survey project, Coastal Frontiers also monitored the beach nourishment program with UAV flights and bathymetry surveys at depths of 10-60 ft using its CEE ECHO™.

With active dredging and sediment resuspension, survey conditions were tricky at times, and advanced QA/QC supported by the CEE ECHO™ was useful:

“The digital echogram efficiently mapped both the top and bottom of the loosely-consolidated layer. We were die-hard paper chart users, but since using the CEE ECHO™ we would never consider surveying without a digital echogram.”

Coastal Frontiers

The results

In combination with wading and land survey data, a complete topographic map of the entire lagoon system was generated for the project managers.

Extensive use of digital echograms in HYPACK represented a welcome departure from the “old ways” of the paper chart echo sounder.