Evaluation of the laser diffraction method for the measurement of suspended sediment concentration in Mogi-Guaçu reservoir (São Paulo, Brazil)

The hydrosedimentological monitoring with reliable data of suspended sediment concentration can be problematic when conventional methods are employed because these methods usually show measurements with stations and frequencies lower than desirable, therefore limiting the studies and the management of water resources. In this context, this paper shows a study carried out in the Mogi-Guaçu reservoir (São Paulo, Brazil) in which the correlation of data from sediment in suspension concentration was made, measured with automatic device (LISST-100X) and conventional sampling. By linear regressions and statistical tests, the efficiency of laser diffraction technique was assessed, and the concentrations of suspended sediments were estimated, for both of the performed campaigns. Through the statistical analysis of the results, it was possible to confirm that among all scenarios of linear regressions adopted, the model that divides the reservoir in sectors shows better concentration estimates, inferring that the concentration of suspended sediment has a characteristic behaviour of the segment of the Mogi-Guaçu reservoir. Therefore, the LISST-100X herein proved to be feasible for the case study. It should be noted that the use of this probe made it possible to obtain more data than those obtained using conventional techniques, enabling a more complete analysis of the reservoir and significantly reducing the work in the field, laboratory and office.