Sediment Budgeting in Laboratory Plots under Rainfall Simulation

Sediment production at each stage of erosion and its redistribution vary at different scales in a watershed, a slope and even a plot. The preparation of sediment budgets on watershed and slope scales have been considered in the two preceding decades, and a review of this tool on a plot scale can also help to better understand the process of sediment production, redistribution and delivery. The present study was conducted to budget sediments in laboratory plots with sandy-loamy soil and under rainfall simulation with the intensities of 30, 50, 70 and 90 mm h-1. Sediment tracing was performed on the surface of the plots by measuring the changes in the density of synthetic color-contrast aggregates using image processing. The results indicated the ability of this method to prepare sediment budgets on a plot scale. The contribution of interrill erosion in sediment production was increased with an increase in the rainfall intensity; however, the proportion of sediment redistribution within the plot was decreased. The average sediment delivery ratios for the rainfall intensities of 30, 50, 70 and 90 mm h-1 were 7.30, 8.54, 11.74 and 15.64%, respectively. The insignificance of this ratio on a plot scale was emphasized due to the short period of the experiment and should be considered in laboratory research projects.