Determining Effective Factors on Gullies Development in Mazayjan Watershed, Fars Province, Using Multivariate Statistical Methods

Gully erosion is one of the causes of land degradation, which causes a lot of damage with the loss of fertile soil. For this purpose, in the present study, using the Cochran relation, 40 gullies were selected for measurement in the Mazayjan watershed located in the southeast of Fars province. Factor analysis method was used to determine the factors affecting the classification of samples. Backward multivariate regression was used to determine the most effective factors in the formation, expansion and production of gutter sediment. The results showed that the creation area of ​​the gullies is a function of the variables of bare soil, organic matter and sand. So that with each percentage increase of bare soil, the amount of 0.379 is added to the creation area of ​​the watershed and at the rate of each unit, the percentage of soil organic matter and the percentage of sand are 0.349 and 0.363 units of the creation area are reduced respectively. Also, in determining the factors affecting the volume of gullies, the percentage of sand was the most important factor was reducing the volume of gullies. Therefore, in order to prevent the development of gullies and reduce the production of sediment, more attention should be paid to erosion control in the headcut's gullies. It helped reduce gully erosion by increasing roughness and reducing runoff.