Some Causes of Gully Formation in Two Catchments of Naviz and Hashan as Found through Remote Sensing and Geographical Information System

Gully erosion is a serious problem for land use/cover in many parts of the world, because of the characteristics of climate, lithology, soils as well as relief. In contrast to sheet and rill soil erosion, relatively few studies have been focused on investigating gully erosion during the last decades. The causes of gully erosion have recently aroused the interest of many researchers in different environments. The ongoing research was applied to two catchments (5397.36 ha) located in Taleghan watershed.¬ The boundary of the gullied area was drawn on orthophoto produced on aerial photographs. ¬Land use/cover map was depicted on satellite images. The digital maps of geology, soil, rainfall, temperature, climate, land use/cover, altitude, slope and aspect were used for a study of their combination in relation with the gullied area. Then the digging of profile was carried out in the region. Results indicate, gullies have been formed on Neogen formation by parent materials of marl, slope less than 15%, southern aspect, humid and semi humid climates. Land use and soils in the gullied area are respectively, rangeland, and Typic calcixerepts and Typic Haploxerepts. The rate of silt is high in the gullied area and the rate of clay has caused increase in soil depth in the gullied area. The rate of gully retreat from 1370 to 1380 is estimated as 3.34 hectares.