Case study by SPH Engineering · Ground Penetrating Radar · Bathymetry
Can a high-frequency drone GPR measure water depth?
Water depth is normally measured with echo sounders, and when GPR is used it is usually a low-frequency unit. SPH Engineering and Frontier Precision Unmanned tested a 500 MHz Radar Systems Zond Aero 500 GPR on a drone over a pond with limited access, and compared it with an ECT400 echo sounder system.
The challenge
Low-frequency GPR is the usual choice when radar is used for bathymetry. The trial set out to test whether an integrated drone system with a high-frequency 500 MHz GPR could also do the job, over a pond with limited physical access.
The method
- Two systems were flown: the airborne ECT400 echo sounder for standard depth readings, and the GPR for the test.
- The drone flew very low, with 30 cm between the GPR antenna and the water, so the radar could record the water column.
- The GPR data was processed in Geolitix, then imported into Eye4Software Hydromagic for display and comparison with the echo sounder data.
The result
The GPR depths closely matched the echo sounder. Comparing the echo sounder check lines with the GPR survey lines showed a difference of only a few centimetres. SPH Engineering concludes that GPR, though not designed for bathymetry, can give accurate depths under specific conditions, such as water with low conductivity.
The team also developed a simple workflow for processing GPR bathymetry data. Echo sounders remain the standard, but the trial suggests GPR can be an option in specific cases. SPH Engineering has published the dataset for download.
Where this applies in India
This is a trial result, so it suits teams exploring methods rather than routine production work:
- freshwater ponds and lakes with low conductivity;
- survey firms that already fly GPR for utility or ground work and want occasional depth checks;
- research institutes comparing radar and sonar methods.
SPH Engineering's GPR training and bathymetry training are also available through HobiTech.
The equipment, available from HobiTech
| Ground penetrating radar | Radar Systems Zond Aero 500 |
| Echo sounder | ECT400 was used in this trial. We sell the EchoLogger ECT 400S. |
| Processing | Geolitix (GPR) and Eye4Software Hydromagic (depth maps) |
| Drone | The case study does not name the drone. Ask us for current compatible drones. |
Case study by SPH Engineering, published October 2023. This page summarises it in our own words; the trial was carried out by SPH Engineering and Frontier Precision Unmanned, not by HobiTech. Read the original case study on SPH Engineering ↗
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