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Mulches have extraordinary potential in reducing surface runoff, increasing infiltration of water into the soil and decreasing soil erosion. The straw mulches as a biological material, has the ability to be a significant physical barrier against the impact of raindrops and reduce the detachment of soil aggregates. The present study is an attempt to determine the efficiency of straw mulch as conservation treatment in changes in the splash erosion, time-to-runoff, runoff coefficient, infiltration coefficient, time-to-drainage, drainage coefficient, sediment concentration and soil loss. The laboratory experiments have been conducted for sandy-loam soil taken from deforested area, about 15 km of Warsaw west, Poland under lab conditions with simulated rainfall intensities of 60 and 120 mmh–1, in 4 soil moistures of 12, 25, 33 and 40% and the slope of 9%. Compared with bare treatments, results of straw mulch application showed the significant conservation effects on splash erosion, runoff coefficient, sediment concentration and soil loss and significant enhancement effects on infiltration and drainage. The results of Spearman-Rho correlation showed the significant (p < 0.05) correlation with r = –0.873, 0.873, 0.878 and 0.764 between rainfall intensity and drainage coefficient, downstream splash, sediment concentration and soil loss and with r = –0.976, 0.927 and –0.927 between initial soil moisture content and time-to-runoff, runoff coefficient and infiltration coefficient, respectively.

Understanding the processes of displacement and redistribution of soil particles caused by different erosion types is considered an efficient sediment management tool in various scales from the field plot to the watershed. The rainfed agriculture practices on high gradient slopes are one of the main sources of accelerated soil erosion due to the disturbance of soil structure by tillage processes. Therefore, the present study aimed to investigate the synergistic effect of rainfed agriculture practices and slope gradient on soil erosion using the activity concentrations of 137Cs fallout in Khamsan experimental watershed, western Iran. The diffusion and migration model was used for undisturbed soils and mass balance equation type II was used for agricultural lands. The distribution map of soil erosion and deposition of the watershed was prepared using 137Cs method and the interactions between rainfed agriculture and slope gradient (as the most effective geomorphological factor) on erosion rate and sediment redistribution were evaluated. The results indicated that the highest rates of soil erosion in rainfed agriculture (11.46 t ha-1 year-1) and rangeland (1.27 t ha-1 year-1) were recorded in the slope gradient classes of 20%-30% and >60%, respectively. In addition, the maximum sedimentation in rainfed agriculture (5.78 t ha-1 year-1) and rangeland (0.89 t ha-1 year-1) occurred in the slope classes of 30%-60% and in >60%, respectively. [ABSTRACT FROM AUTHOR]

Soil erosion by water as a natural process can occur in all climates and zones and change all landforms. As the measuring of soil erosion is costly and time consuming process, dozens of erosion prediction models have been developed and the aim of the majority of all of them is to predict average rates (often an annual average rate) of soil loss from an area such as a plot, a field or a catchment/watershed under various land management techniques. On the other hand, outflow is the most important element of the hydrological cycle and that is why it is important to determine it as accurately as possible by measuring and predicting. Therefore, the IntErO (Intensity of Erossion and Outflow) model based on the EPM (Erosion Potential Method) method was used for calculation of outflow and sediment yield in the S2-1 watershed of Shirindareh River Basin in the Northeast Iran with the area of 46.77 km2. According to the results, the predicted peak discharge was 101 m3 s-1 for the incidence of 100 years and the specific sediment yield was 267 m3 km-2 year-1. According to the previous studies and topographic characteristics, the river basin watershed belongs to the V category and has very weak erosion. The results of the present study and previous experiences of the other researchers revealed that the IntErO model can be used to estimate soil loss in the other regions similar to Shirindareh River Basin. [ABSTRACT FROM AUTHOR]

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-2were 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. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]