DETERMINATION OF SUSPENDED PARTICULATE MATTER CONCENTRATION FROM TURBIDITY MEASUREMENTS : PARTICLE SIZE EFFECTS AND CALIBRATION PROCEDURES

Measurement of suspended particular matter concentration and turbidity point toward the possibility of a site-specific algorithm (SPM), relating SPM to nephelometric turbidity units (NTU). Regression model are presented that account for changes in the relationship of SPM and NTU as a result changes in particule properties. Variation of the slope of a linear regression equation according a logistic function with slope varying continuously with hydraulic parameters may account for the effect resulting from changes of particule characteristics and thus may have some advantages compared with models with a constant slope or models calibrated for different seasons.