Calibration of the soil loss measurement method at the Masse experimental station

The paper introduces the results of the calibration of the runoff and sediment concentration measurement system adopted at the Masse experimental station recently set up by the Department of Civil and Environmental Engineering to study erosion processes at the plot scale in Central Italy. The collected runoff is stored in cubic tanks equipped with ten taps for sampling the suspension. When an erosive event occurs, the plot runoff volume is measured by means of the water level in the tank, and the corresponding mean measured concentration in the suspension is quantified. The calibration curve of the specific storage system and of the measurement procedure used makes it possible to derive the actual concentration. The event plot soil loss is quantified as the product of the actual concentration and the runoff volume. The calibration curve was determined for two soil types. In any case a linear relationship was found between an actual and measured concentration. Slopes of regression vary with water depths in the tank. The calibration model does not significantly vary with the soil type considered due to the low difference in the coarse sand percentage in the two soils (according to Stokes' law). The measurement devices and the sampling procedure being equal, the calibration curve determined can be used to correct the measured concentration in the actual concentration for any soils that are characterized by a coarse sand percentage similar to that of the soil used to derive it.

► Sampling from a plot tank underestimates the actual soil concentration.
► The actual/measured concentration ratio has been determined for the Masse Station.
► The ratio is constant for a given water level in the tank.
► The relationship is the same for soils with similar coarse sand percentage.