Cutting storm pond survey time by 75% with a drone echo sounder

The challenge

Urban Systems surveys storm ponds, from small urban basins to mid-sized retention areas, and tested its workflow in fast-flowing river sections. The aim is to monitor sediment and calculate volumes. Its boat-based workflow had several recurring problems:

• Repeat passes: crews often covered the same area several times to be sure of full coverage, which made field days long.
• No live check: without real-time feedback, gaps were sometimes found later and crews had to go back.
• Access: steep banks, dense vegetation and remote sites made boats hard to launch and recover.
• Safety: rivers and high water put people in boats at risk.
• Equipment risk: unmanned boats carried costly RTK GNSS receivers that could be lost if a boat capsized or failed.
• Slow processing: raw CSV data was cleaned by hand in CAD, which took 15 to 20 hours per project.

The solution

In 2023 the firm adopted SPH Engineering's drone-mounted echo sounder system. It combines:

• an ECT D052S echo sounder;
• UgCS for mission planning and autonomous flight;
• Hydromagic to process the sonar data into surface models;
• CAD for the final volume and contour deliverables.

Flight paths are planned for each site as overlapping lines that cover the whole bottom, and flown within visual line of sight. The depth models are then aligned with existing topography, often from aerial LiDAR or earlier as-built surveys, so sediment build-up can be tracked over time.

The results

• Field time fell by about 75%. A survey that took a full day by boat now takes under two hours, so the team can cover several sites a day.
• Clean-up and modelling dropped from over 20 hours to under four hours per site.
• UgCS removed redundant passes. Rae Robertson, LiDAR and drone specialist at Urban Systems, said this saves both field and processing time.
• Real-time monitoring and Hydromagic helped confirm complete coverage, so fewer return visits were needed.
• Steep-banked ponds and fast rivers could be surveyed without anyone entering the water, and the GNSS gear stayed off the water.

Principal James Mackinnon said that almost every bathymetric survey can now be done in a quarter of the field time. The firm plans to extend the method to larger rivers and longer cross-section surveys.

Where this applies in India

Consultancies and engineering teams in India handle the same kind of repeat depth work. The workflow suits:

• stormwater ponds and drains in cities, townships and industrial parks;
• urban lakes and tanks before and after desilting;
• river inlets and cross-sections for drainage and flood studies;
• survey firms that need to cover more sites per day.

SPH Engineering's bathymetry training is also available through HobiTech.

The equipment, available from HobiTech

Echo sounder	EchoLogger ECT D052S
Flight planning	UgCS - Drone Flight Planning Software
Onboard computer	SPH Engineering's drone echo sounder system runs on SkyHub by SPH Engineering with the SkyHub echo sounder software
Drone	The source does not name the drone. Ask us for current compatible drones, such as the DJI Matrice 350 RTK.
Processing	Hydromagic and CAD software (used in the project)

Case study by SPH Engineering, published April 2025. This page summarises it in our own words; the surveys were carried out by Urban Systems, not by HobiTech. Read the original case study on SPH Engineering ↗