Soil loss and runoff generation in rangeland, rain-fed and abandoned rain-fed agriculture land-uses under simulated rainfall

Document Type: Research Paper

Authors

1 MSc Graduate, attended the faculty of watershed management, Islamic Azad university, Meybod, Iran,

2 Department of GIS-RS and Watershed Management Eng., Maybod Branch, Islamic Azad University,

3 attended the faculty of watershed management, Hormozgan University, Iran

4 PhD Candidate in Combating Desertification

5 PhD graduate from Gorgan Univ. of Agricultural Sciences and Natural Resources

Abstract

Soil erosion is a global challenge, seriously threatening soil and water resources and
environmental qualities. One of the important factors to consider in the process of runoff
generation and soil erosion is the physical and chemical properties of soils under different
land-uses. The aim of this study is to estimate soil erosion and runoff in rangeland, rain-fed
and abandoned rain-fed agriculture in Karafs Watershed (Sarduyeh) in Jiroft County using
rainfall simulation. The experiment was conducted in 2012 and three land-uses with
uniform soil and lithology were considered. Simulated rainfalls were 46 and 88 mm.hr-1 of
intensity with 3 iterations, which totaled 36 samples. Soil samples were taken close to the
locations of rainfall simulation from the top 0-20 cm and transferred to the laboratory for
further analysis. The results showed a significant effect of land-use on runoff and erosion in
different rainfall intensities, so that the highest runoff was generated in the abandoned rainfed
agriculture at the intensity of 88 mm.hr-1, with the least being generated in the rain-fed
agriculture at the intensity of 46 mm.hr-1. Likewise, we found that land-use changes had a
large impact on soil erosion, with the highest levels at the abandoned rain-fed agriculture
which resulted in the increased runoff generation. This factor could be explained by the
increased clay, silt, and lime content at the expense of the removal of sand from these areas.
Increasing rainfall intensity to 88 mm.hr-1 led to respectively 14% and 47% higher runoff
volumes and sediment loads compared to the initial intensity.

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