Document Type : Research Paper
Authors
1 Department of Arid and Mountainous Region Reclamation, Faculty of Natural Resources, University of Tehran, Karaj, Iran
2 Soil Conservation and Watershed Management Research Institute (SCWMRI), Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
Abstract
Understanding the processes of soil degradation, including erosion, is crucial for its conservation, given the lengthy process of soil formation. Among various forms of soil erosion, the damage caused by mass movement and gully erosion is particularly significant at the watershed scale. This phenomenon is considered an objective and key criterion for assessing the severity of land degradation. The current research aims to determine the extent of gully erosion across Iran and investigate its relationship with climatic elements (temperature and precipitation) and its impact on erosion and sedimentation at the watershed scale. Initially, a primary database on gully erosion was established through a review of articles, theses, reports, projects, and consultations with specialists, followed by the use of Google Earth and field visits for validation. By integrating the gully erosion layer with provincial boundaries,climate (De-Martonne), and second-order watersheds ,the extent of gully erosion in each of these areas was determined. Finally, the relationship between climatic elements, total erosion and sedimentation, and specific sediment yield with gully erosion at the second-order watershed scale was examined. The results indicate that the total area affected by gully erosion is 3,207,314 hectares.Golestan Province, the semi-humid climate, and the Gorganrud-Qarasu watershed have the highest relative density of gully erosion, with values of 15.3, 2.2, and 20.8, respectively.The relationship between specific sediment yield, total erosion and sedimentation, and the area affected by gully erosion is significant and positive, with an increase of one unit in gully erosion area leading to an increase of 209.81 tons per square kilometer per year in sediment yield.Therefore, to determine the vulnerability degree of second-order watersheds and prioritize regions requiring soil conservation measures, factors such as the status of agricultural land use, presence of dams, road conditions, and elements at risk should be considered, alongside the likelihood of gully erosion occurrence.
Keywords
)