A study on the effective factors on sediment production by gully erosion in different climates of Fars province

Fars province has experienced gully erosion in six climate zones based on de Martonneclassification method. After selecting one region from each climate zone, 15 active andrepresentative gullies were investigated using morphometric characteristics andwatershed area, slope gradient above gully heads, linear advancement, form factor,particle size analysis, vegetation cover, gravel content and bare grounds were measuredand sediment production was calculated. Effective factors on sediment production dueto gully erosion were determined using Stepwise method provided in the SPSS softwarepackage. The results of this research revealed that four factors including slope gradient,maximum 24 hours rainfall, sand, and form factor had significant impact on sedimentproduction with 99 percent of confidence. Slope gradient above the gully head was themost important factor on the sediment production. Slope gradient and form factor hadpositive relationship and maximum 24 hours rainfall and sand had negative relationshipwith gully development. The most important impact of slope gradient on the sedimentproduction implies the velocity of surface runoff concentrated above gully heads.Alternative controls to decrease slope gradient would be effective on the reduction ofgully development and sediment production.