Abstract

Water erosion creates negative impacts on agricultural production, infrastructure, and water quality across the world. Regional-scale water erosion assessment is important, but limited by data availability and q uality especially in countries such as Iran. For this purpose, we studied water erosion in parts of Aras river catchment covering an area of 39478 km² which is located in Iran. The Aras River basin is a part of the Caspian Sea basin, which is located at 44°03´ to 48°41´ east longitude and 37°47´ to 39°46´ north latitude. The Aras River, being the most important water region in quantity of water, as regards to other regional rivers; originates from Mingoldagh mountains in Turkey. We utilized such parameters of effectiveness in soil erosion as geology, climate, runoff, topography, vegetation cover, land use, drainage density, main stream length, concentration time; combined with shape index studied for some hydrologic units of a selected homogeneous region. Regression form regional relations were then developed using sediment, physiographic, hydrologic and vegetation cover information. The results and fitting regression models indicate that factors of runoff height, drainage density, vegetation cover and runoff coefficient, were selected and suitable model by variables of drainage density, vegetation cover and bare land percentage has been present by method of backward variable selection. These results necessitate the soil conservation projects to be carried out in the studied area.

Keywords: Aras catchment, regional-scale relations, water erosion