Author(s): Kota Shimizu; Shun Saito; Takehiro Oki

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Keywords: Green laser; Reservoir sediment management; IRIC

Abstract: This study reports on the use of a green laser mounted on an unmanned aerial vehicle (hereinafter, “green laser”) that can survey land and underwater areas in single survey of dam sediment topography and on the use of the obtained 3D topographic data. The study subjects are three hydropower dams in Hokkaido, Japan. Sedimentation has been progressing in these three dams in recent years. The main findings of the study are as follows: 1) a green laser can be used to survey a dam’s topography, and the relationship between the critical water depth and turbidity for green laser measurements was clarified, 2) the survey error is within the accuracy required of public surveys in Japan, and 3) a narrow multibeam and a green laser can be used in combination on a boat in a reservoir with great local water depths. For surveys from a boat using a narrow multibeam and a green laser, it was found possible to conduct reservoir operation in which the target water level depended on the chosen measurement method. Furthermore, based on the high-density 3D topographic data acquired in the green laser survey, a sediment flushing simulation was performed and an analytical model was constructed to enable examinations for future sediment flushing. This study demonstrated that a green laser can be used to determine the dam sediment topography and that the acquired topographic data can be useful.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P2015-cd

Year: 2025