Measuring sheet erosion using synthetic color-contrast aggregates

Abstract

The bulk of eroded soils measured at the outlets of plots, slopes and watersheds are suspended sediments, splash-induced sheet erosion. It is depending on rainfall intensity and antecedent soil moisture contents and contributes to a significant proportion of soil loss that usually is ignored in soil erosion and sediment studies. A digital image processing method for tracing and measuring non-suspended soil particles detached/transported by splash/runoff was therefore used in the present study. Accordingly, fine mineral pumice grains aggregated with white cement and coloured with yellow pigment powder, with the same size, shape and specific gravity as those of natural soil aggregates, called synthetic color-contrast aggregates, were used as tracers for detecting soil particle movement. Subsequently, the amount of non-suspended soil particles detached and moved downward the slope was inferred with the help of digital image processing techniques using MATLAB R2010B software (Mathworks, Natick, Massachusetts, USA). The present study was conducted under laboratory conditions with four simulated rainfall intensities between 30-90 mm h -1 , five antecedent soil moisture contents between 12-44 % v v -1 and a slope of 30%, using sandy loam soils taken from a summer rangeland in the Alborz Mountains, Northern Iran. A range of total transported soil between 90.34 and 1360.93 g m -2 and net splash erosion between 36.82 and 295.78 g m -2 were observed. The results also showed the sediment redeposition ratio ranging from 87.27% [sediment delivery ratio (SDR) = 12.73%] to 96.39% (SDR = 3.61%) in various antecedent soil moisture contents of rainfall intensity of 30 mm h -1 and from 80.55% (SDR = 19.45%) to 89.42% (SDR = 10.58%) in rainfall intensity of 90 mm h -1 .

Reducing sediment concentration and soil loss using organic and inorganic amendments at plot scale

“…The bulk density, pH, electrical conductivity and organic content of the study soil were measured as 1.376 g cm −3 , 7.95, 75.5 µmohs cm −1 and 2.167 %, respectively. The collected soil was carried to the lab and air dried to optimum moisture content to maintain the relative stability of the soil aggregates (Kukal and Sarkar, 2011;Khaledi Darvishan et al, 2014;Moreno-Ramón et al, 2014;Brevik et al, 2015). The pebbles and plant residues were removed from the soil by passing it through a 8 mm sieve to obtain maximum similarity with the soil natural conditions (Defersha et al, 2011;Khaledi Darvishan et al, 2014;Ziadat et al, 2013).…”

The impact of standard preparation practice on the runoff and soil erosion rates under laboratory conditions

“…The collected soil was air-dried to the optimum soil moisture content (Fox and Bryan, 1999). All plant residues and pebbles were removed from the soil (Agassi and Bradford, 1999), and finally the soil was passed through a 8.0 mm sieve (Ekwue and Harrilal, 2010;Defersha et al, 2011;Khaledi Darvishan et al, 2014). The prepared soil was then transferred into the nine plots with the depth of about 15 cm.…”

Effect of Exclosure on Runoff, Sediment Concentration and Soil Loss in Erosion Plots

“…The collected runoff samples transferred to the laboratory and sediment concentration was measured using decantation procedure and oven drying at 105°C for 24 h and weighed by high-precision scales Khaledi Darvishan et al, 2014).…”