Performance assessment of a bathymetry system in open inland waterbodies

Bathymetry of an open waterbody can be estimated re-motely using airborne and space-borne sensors with wide coverage. However, unmanned aerial vehicle (UAV)-borne bathymetric systems are current trends for appli-cations with limited depth subjected to the quality of water. Estimation of accurate bathymetry using surface -based sensors is essential for validating the remote sens-ing-derived results. To cater to the requirements of the in situ measurement system, especially for supporting the airborne (aircraft/UAVs) remote sensing-based bathyme-try systems, a customized and compact, immersion-type bathymetry system using single-frequency (typ. 500 kHz) transducer was developed in-house at the National Re-mote Sensing Centre (NRSC), ISRO, Hyderabad. In the present study, we assess the performance of the develo-ped system in the field against physical measurements and a reference acoustic transducer for shallow and deep inland open waterbodies. Performance testing was car-ried out in the Asan Lake, a shallow waterbody, with a depth of up to 4 m and in the Tehri reservoir for deep ba-thymetry with a depth of more than 150 m. The results show that the estimated TVU for the developed system during shallow bathymetry assessment was 0.272 m which complies with the IHO order 1. The observed per-formance of the developed system was consistent with the system specifications, which advocate its utility for hydrology and water resource management applications along with its intended use to support remote sensing -based bathymetric systems.