Bathymetry reconstruction using UAV-mounted Echo-sounder and Lidar sensors: a case study

This study investigates a UAV-mounted sonar approach for bathymetric mapping in complex inland water bodies, addressing challenges that hinder traditional methods like satellite-based remote sensing and USVs. Optical satellite imagery, while valuable in clear shallow waters, is limited in turbid environments. Likewise, inland waters often feature obstacles—boulders, vegetation, and anthropogenic debris—that impede USV navigation. This study introduces a UAV-tethered sonar device to overcome these constraints, leveraging UAV mobility to access remote areas and sonar precision to capture accurate depth data in deep and murky conditions. Tests in Conza della Campania reservoir, Italy, compared this method to LiDAR, showing that UAV-based sonar provides reliable bathymetric models and can detect submerged objects. Dual-frequency sonar (50 kHz, 200 kHz) captured detailed profiles, with low frequencies effectively penetrating debris-heavy water. This approach proves valuable for bathymetric reconstruction in complex environments, offering an accessible, scalable solution for inland water studies.