Study and morpho-climatic classification of gullies in the Khozestan province of Iran

This study investigated the characteristics of morpho-climatic classification the Khozestan province and the factors affecting the on trends and development of the gully erosion process areas. First, the available data in the Khozestan province were collected and after their compliance with the data obtained from satellite images and other data, the map of gully regions for the whole province developed. Initial field visits to verify and refine the boundaries of gully erosion were done. The Domarton method was used to map the climate of province which emphasis the role of climate on gully erosion. From the total area of the Khozestan province (6350179 hectares), more than 47.4 present of the province is located in the dry desert and over 33,862 hectares are affected by gully erosion as second order which located in the semi-arid climate which covers about 12.1 percent of the PROVINCE with 16116 hectares of gully areas. Then proceed to determined and separate the gully area over and under 500 hectares. Due to differences in morphology, topography and vegetation cover and also affect a large area of gully, from the climate of hot and dry desert of 2 representatives with two repetitions and from the semi-dry dry 1 representative with 2 repetitions were selected. Surveying and cross sections information from representatives were collected and general plan were drawn. In addition soil samples at different cross section in different lengths and physicochemical tests on samples were taken. The results show that most of gully was located in the plane with low slope and deep soil with sandy loam, or silt loam or silt which are in the rangelands and crops fields where most of them are U-shaped. General plan is Dendrite, in the category of moderate depth (one to ten meters) with vertical head. The average annual precipitation ranges from 280 mm to 350 mm in the region and most of precipitation is in showers form. Most of the gully erosion located in the Aghajari, Mishan and Marls of gypsum-saltly formation. The results show that natural factors such as intrinsic properties of the soils, geology, climate, rainfall intensity and human factor as second factors involved to establish the gully erosion which destroy vegetation in different forms, land use change and mismanagement, wrong operation on road and bridge construction and Construction and installation of oil, Power and Telecommunications facilities help to expansion of gully. Because the soil of these areas are very sensitive to soil erosion on wrong practical operation.