Document Type : Research Paper
Authors
1 Former PhD Student, Sciences and Researches Unit, Azad Islamic University, Iran
2 Assistant Professor, Agricultural and Natural Resources Research Center, Fars, Iran
3 Professor, Watershed Engineering, Sciences and Researches Unit, Azad Islamic University, Iran
Abstract
Fars province has experienced gully erosion in six climate zones based on deMartonne classification method. After selecting one region from each climate zone, 15 active and representative gullies were investigated using morphometric characteristics and watershed area, slope gradient above gully heads, linear advancement, form factor, particle size analysis, vegetation cover, gravel content and bare grounds were measured and sediment production was calculated. Effective factors on sediment production due to gully erosion were determined using Stepwise method provided in the SPSS software package. The results of this research revealed that four factors including slope gradient, maximum 24 hours rainfall, sand, and form factor had significant impact on sediment production with 99 percent of confidence. Slope gradient above the gully head was the most important factor on the sediment production. Slope gradient and form factor had positive relationship and maximum 24 hours rainfall and sand had negative relationship with gully development. The most important impact of slope gradient on the sediment production implies the velocity of surface runoff concentrated above gully heads. Alternative controls to decrease slope gradient would be effective on the reduction of gully development and sediment production.
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