Underwater vehicles for environmental management in coastal areas

Methods for using underwater vehicles for mapping and monitoring are developed continuously. These methods developed must be accurate, quantitative and repeatable while being as cost effective as possible. In 2011, 2012, 2013 and 2014 The Norwegian University of Science and Technology (NTNU) Applied Underwater Robotics Laboratory completed surveys in the Trondheim Fjord area. During these surveys methods relevant for addressing several of these challenges have been tested. We have tested Synthetic Aperture Sonar for establishing baselines for marine habitats and littering. In the sonar data cold-water coral habitats gave a significant signal. These observations were confirmed by video and hyperspectral imaging. We have also revisited the same areas and demonstrated the potential to detect changes. During our campaigns the sonar data has also been verified by ROV video and sampling. A dumping area in the fjord was mapped by the AUV mounted SAS and on a subsequent cruise the ROV was deployed for video survey, stereo photos and sediment sampling. Stereo models may prove an important tool where millimeter resolution and precision is attainable. Based on the experimental work presented in this paper, a proposal for underwater vehicles in environmental management of coastal areas is described.