High concentration suspended sediment measurements using time domain reflectometry

SummaryThe existing methods of suspended sediment concentration (SSC) monitoring provide a measurement accuracy significantly influenced by the particle size of suspended sediments, function only under limited measurement range and are not cost effective for field maintenance as well as wide spatial coverage. The paper introduces an innovative SSC monitoring methodology based upon time domain reflectometry (TDR), especially emphasizing on optimum TDR measurement accuracy investigated theoretically and experimentally. Pertinent probe design, probe calibration, as well as data reduction procedures were proposed. Ultimately, the approach can achieve the measurement accuracy to adapt the derived hardware resolution and beyond. In addition, the performance evaluation was carried out considering possible influence factors including water salinity, sediment types and particle sizes, and leading cable lengths. TDR SSC measurements indicate insensitive to sediment particle sizes. After proper calibration, the measurements are also insensitive to water electrical conductivity and not affected by leading cable resistances. There are further advantages of the TDR method including high measurement range from 2 to at least 300 g L−1, easy calibration, robustness, maintainability, and cost-effective multiplexing.

Research highlights
► A SSC monitoring methodology is proposed based upon time domain reflectometry (TDR).
► Possible influence factors are considered for the performance evaluation.
► TDR SSC measurements indicate insensitive to sediment particle sizes.
► TDR SSC measurements are insensitive to water electrical conductivity.
► TDR SSC method can be applied to high measurement range from 2 to at least 300 g L−1.