Measurement of the deposition of fine sediments in a channel bed

• Calibration of pulsed red laser diode and electrical resistance-based depositometer.
• Comparison of suitable working conditions and limitations of the two instruments.
• A test case: measurement of the deposition of a turbidity current.

Various instruments allowing the measurements of bottom deposits of fine sediments exist. Different techniques are developed in order to suit diverse operating conditions. The present study considers two high-precision instruments, namely, an electrical resistance-based depositometer (ERBD) and a pulsed red laser diode. Both instruments are described and their parallel calibration process discussed, allowing to evaluate their advantages and their limitations. For this goal, fine sediments are left to settle in a confined experimental tank, and their deposits are monitored using the two instruments. The latter are then compared with the aim of providing guidance and recommendations for researchers dealing with sediment depositions in particular in experimental facilities. The ERBD is then tested in monitoring the deposition due to the passage of a turbidity current and it proved to be a valid and affordable technique to track the space and time evolution of fine sediment deposits. On another hand, the pulsed red laser diode was found to be a user-friendly instrument allowing direct measurements of deposition thicknesses.