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Rainfall during Events on Runoff and Soil Loss under Simulated Rainfalls
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Ali Reza Vaezi *   , Farzad Besharat |
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Abstract: (9195 Views) |
| Rainfall intensity is one of the most important factors in soil erosion. Variation of the rainfall intensity during a storm event which is defined as temporal distribution pattern of rainfall may affect temporal variation of runoff and soil erosion. This is an essential problem to accurately estimate rainfall erosivity particularly in semi-arid regions, where various patterns of temporal rainfall distribution occurs during a In this study, eleven non-uniform temporal distribution patterns with basic intensity of 20 mm.h-1. maximum 5-min intensity of 40 mm.h-1 along with an uniform temporal distribution pattern with 20 mm.h-1 in intensity were investigated at twelve erosion plots (60 cm 80 cm) installed in a hillslope with 9% slope in 2012. Each plot was exposed to five simulated rainfalls. There were significant differences among temporal distribution patterns in runoff and soil loss. These differences were associated with soil surface breakdown and declining infiltration rate during peak rainfall intensity period. In the intermediate rainfalls, which the maximum intensity occurred at the middle time during rainstorm, there was the highest value of runoff (1.39 mm) and soil loss (30.31 g.m-2). In these storms, soil was slowly disrupted and wetted by raindrops at early times during the rainfall. However, when rainfall intensity increased, runoff and soil loss remarkably increased and this condition was approximately constant over time. In the advanced rainfalls, amount of runoff and soil loss were 98.51% and 98.63% as compared to the delayed rainfalls. In the delayed rainstorms, although rainfall intensity severely increased at the final periods during the event, the lowest runoff and soil loss occurred because the duration of the maximum intensity was relatively short and the rainfall was immediately stopped. |
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| Keywords: Simulated rainfall, Rainfall intensity, Erosion plot, Semi-arid region |
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Full-Text [PDF 279 kb]
(1673 Downloads)
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Type of Study: Research |
Subject:
Special
Received: 2015/09/8 | Accepted: 2015/09/8 | Published: 2015/09/8
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