Improved light attenuation method for 2D data acquisition of sediment depths

Abstract

An improved light attenuation method [light attenuation method for two-dimensional data acquisition (LAM2D)] to quantify two-dimensional (2D) sediment depths with higher accuracy is developed in the present study. The working principle is to relate attenuated light intensities with depths of the sediment layer. Traditionally, calibration has been performed with the scraper method with either multiple constant sediment depth profiles or a slope with incremental depth profile. This method works well for coarse sediment but is shown to be inaccurate for fine sediment with shallow sediment depth in the near-zero limit regime. In the present study, a new method is established for the calibration of shallow sediment depth by using the correlation of particle plume deposition profiles. The practical application of LAM2D to determine sediment deposition profiles from a laboratory simulation of barged sediment disposal was demonstrated with both approaches. The errors in the overall determination of sediment mass were found to be significantly reduced with the current approach.