1. ALEXANDRU – VLAD LAZAR 1, GHEORGHE – VIOREL UNGUREANU 1,2, ALEXANDRU – DAN IONESCU 1, ANDREI – DANIEL BALAHURA 1*, ROBERT LAZAR 1, ALEXANDRU MAGHER 1 1 SC Marine Research SRL 2 University of Bucharest *vlad.lazar@marine-research.ro

2. Content  1. Introduction  2. Methods  3. Results  4. Conclusions

3. 1. Introduction  Seabed mapping – great importance for marine management  Acoustic Seabed Classification (ASC) - applications in marine geology and biology, environmental sciences, coastal engineering and fisheries  Goal – discussing the use of interferometric sonars for ASC  Geophysical methods – coverage, non- invazive  Case study – 42 ha site offshore Mangalia

4. 2. Methods  Interferometic sonar – Kongsberg GeoSwath Plus 250  Positioning and motion compesation – Applanix POS MV 320  Ground-truthing – grab samples and ROV  Sediment type – laser grain size analysis

5. Why interferometric sonar?  Co-register bathymetry and side scan sonar data  Millimeter depth resolution  240 ⁰ field of view  Up to 12 times water depth coverage  high productivity  Integrated IMU and real time motion corrections

7. Processing Bathymetry Side scan  Amplitude Remove water column  Range (Along-Across)Gain corrections  Swath Swamp

8. 3. Results 250 m Bathymetry mapSide-scan mosaic

9. Type 1 Rocks  High rugosity  Large bathymetry variations  Strong backscatter Type 2 Limestone platform  High rugosity  Smaller bathymetry variations  Strong backscatter

10. Type 3 Soft sediments  Low rugosity  Small bathymetry variations  Low backscatter  Moderate rugosity  Small bathymetry variations  Medium backscatter Type 4 Covered limestone platform

11. ROV inspection - Rocks Laser Grain-size analysis – fine sand

12. Acoustic Seafloor Classification

13. 4. Conclusions  Fast evolution of geophysical methods  compact, more and better results  Interferometers are a valuable tool for ASC  Combined methods  Easy to detect seafloor types  Ground truthing and ROV images are very important for quality results

14. Thank you! www.marine-research.com