Near-shore drone bathymetry for coastal erosion monitoring

The challenge

Erosion is an active concern on the Chalkidiki coast, where seabed sediment shifts from season to season. Geosense needed accurate depth data to assess shoreline change and underwater topography. The area was too large for manual measurement, and boat-based echo sounding is slow and difficult in shallow water.

The site also had to be handled carefully:

• shallow water where boat access is limited;
• a changing seabed close to the shoreline;
• obstacles such as rocks, buoys and pipes;
• wind gusts of up to 8 m/s;
• sailing boats occasionally crossing the survey area.

This called for careful planning, stable equipment, obstacle mapping before the survey and constant visual line of sight.

The solution

Geosense flew SPH Engineering's drone bathymetry kit on a DJI Matrice 300 RTK. It combined an EchoLogger ECT D24S dual-frequency single-beam echo sounder, the SkyHub onboard computer and UgCS flight planning software. The setup allowed steady, low-altitude data collection in water where boats are slower or less safe.

A two-stage workflow

First, the team made an orthomosaic of the coastline. It used this to fix the shoreline at 0 m, find rocks, floating obstacles, pipes and buoys, and plan the water flights safely.

The bathymetric flights followed in November, outside the main tourist season, to avoid boat traffic and beach activity. The drone flew about 1.9 m above the water at 0.8 m/s. Fieldwork took 3 days and about 14 hours of flight.

The result

The data was processed into a detailed bathymetric model. Vertical accuracy and point density were in line with IHO (International Hydrographic Organization) Order 1 expectations for near-shore work. Geosense delivered a .dwg CAD file with:

• high-density depth points;
• an accurate outline of the shoreline;
• depth contours at 50 cm intervals.

The dataset is a baseline for local authorities and stakeholders. Future surveys can be compared against it to track erosion and plan coastal protection.

Where this applies in India

Drone bathymetry fills the shallow strip next to the shore that boats find hard to cover:

• beaches and shorelines under erosion monitoring;
• approaches to small harbours, jetties and fish landing centres;
• estuaries, backwaters and lagoons;
• baseline surveys for coastal protection works and environmental impact studies.

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

The equipment, available from HobiTech

Echo sounder	EchoLogger ECT D24S
Onboard computer	SkyHub by SPH Engineering with the SkyHub echo sounder software
Flight planning	UgCS - Drone Flight Planning Software
Drone	DJI Matrice 300 RTK was used in this project. Ask us for current compatible drones.

Case study by SPH Engineering, published June 2026. This page summarises it in our own words; the survey was carried out by Geosense, not by HobiTech. Read the original case study on SPH Engineering ↗