Application of the two-ADCP technique in estuaries to characterize the suspended particulate matter transport

摘要

Acoustic methods have been proved as powerful tools for measuring the concentration and size of suspended particulate matter (SPM) in aquatic environments predominantly composed of non-cohesive sandy sediments and with the predominance of steady flows. However, if flocculation occurs and flows are unsteady, interpretation of the acoustic observations is harder. To provide a solution to the complex characterization of the suspended particles in estuarine systems, in this study two acoustic Doppler current profilers (ADCP), working at different frequencies, are simultaneously employed to obtain the concentration and size distributions of SPM throughout selected transversal sections of a stratified estuary under quiet meteorological conditions and with low river discharge. The intensity of the ADCPs backscatter signal is calibrated with LISST-25X measurements. The information obtained in-situ with high temporal and spatial resolutions is combined with aspects of the estuarine circulation to give a global description of the dynamical behaviour of SPM.