Qualitative Assessment and Risk Zoning of Soil Erosion with a Risk Index Approach in Alvand Karstic Basin, Kermanshah Province

Soil erosion is one the main threats to water and soil resources in the world, as well as arid and semi-arid country of Iran. Soil erosion have a strong relationship with vegetation type and land use. Soil erosion especially in the karst areas led to phenomenon of Rock desertification and to block the channels of karst. The present paper aims at studying the karstic basin of Alvand River in the west of Kermanshah province for three years 1990، 2005 and 2018 by applying Erosion risk index model and satellite images Thematic Mapper (TM) and Operational Land Imager. The findings reveal that the vegetation of Arvand basin has had a decreasing rate in which 30% of the area has decreased from 1990 to 2018. The number of land use classes and their area during this time period have had significant changes. In the selected years, there was no very low erosion zone in any final maps of erosion in the basin. The medium erosion zone has the largest area in all three final maps of the soil erosion. The high and the low erosion zones have been the second and the third wide erosion zones in all the three final maps of the soil erosion, respectively. The very high erosion zone has been consistent with the karst area of the basin. Slope, heavy rainfall, and low-thickness soil have been the most important reasons for high soil erosion in the karst areas of the basin