Water level measurement for reservoir dams with robotic total station during displacements monitoring

Abstract This study proposes a novel method for water level measurement of reservoir dams by utilizing the image sensor of robotic total station rather than requiring a staff gauge during displacements monitoring. The robotic total station is first aimed at the waterline manually and an image is captured by the telescope coaxial camera to obtain the initial elevation and waterline equation. In the periodic measurement stage, the zenith angle of the telescope is adjusted according to the predicted result to take pictures, and the waterline is extracted based on the parameters of the initial waterline equation through image processing technologies. The waterline is verified, and the water level elevation is estimated then. Simulation and field test results show that waterline extraction error affects the accuracy of the proposed method most, and an accuracy of around 2 pixels can be achieved for the waterline extraction method. And a water level measurement result with centimeter-level accuracy at a distance of about 350 m can be expected, which has engineering application prospect.