Author(s): Tianxu Han; Masayasu Irie; Takashi Yamano; Daiki Sakai
Linked Author(s):
Keywords: Turbidity; Suspended solid; Camera; Optical fiber; The Yamato River
Abstract: The turbidity in Japanese rivers is measured using telemetric water quality monitoring systems, and these data are valuable for monitoring sediment transport and maintaining a biologically healthy river environment. Observations during rain and runoff are crucial for sediment transport, but it is difficult to expand the monitoring coverage beyond relying manually. This study investigates the use of camera images and fiber-optic observations to enhance turbidity monitoring. We deployed a trail camera 17.03 km from the mouth of the Yamato River in Japan to acquire images during rain. As a result of various examinations using camera images, this study analyzed the CIE-L*a*b* color space and the number of pixels of white waves on the surface during rainfall to find a correlation between the number of white pixels generated by waves and turbidity. We also assembled a device using a fiber-optic sensor to measure the vertical profiles of turbidity, installing it at the same site below the water quality monitoring station, which also measures turbidity. The vertical distance between the channels was 25 cm. The newly developed low-cost device using optical fiber sensors can remotely monitor the vertical profiles of suspended solids (SS) converted from those of light intensity. The maximum turbidity and SS values appeared almost at the peak water level or slightly earlier, and a nearly constant vertical distribution was obtained. Finally, we packaged the device into a portable device and performed the measurements.
Year: 2024