JWSS - Journal of Water and Soil Science

  Erosion features map is one of the basic maps in erosion and sediment studies considered important in watershed management programs. For preparing soil erosion features map (1:250000 scale), a study was conducted in Jajroud sub-basin of Tehran, Iran. Working unit maps were prepared from integrating: A) plant cover, geology and slope B) land-use, geology and slope C) land-use, rocks sensitivity to erosion and slope and D) land-use, rocks sensitivity to erosion and land units. Working unit maps obtained from integrating layers were compared with three other maps consisting of working units maps according to E) land units F) rocks sensitivity to erosion units and G) image photomorphic units. Erosion features intensities in 314 control points were controlled and erosion features ground truth map was prepared by Thiessen method and using satellite imagery. Erosion features map was crossed with different working unit maps. Results showed that D map was better than A, B and C maps with regard to economic considerations. Accuracy was 53.0 and 42.9% for methods of land unit and rock sensitivity which resulted in the maps not suitable for differentiating soil erosion features. Root Mean Squared Error of working units showed that the error of land unit and rock sensitivity methods was more than image interpretation and integrated layers methods. The highest coefficient of variation was related to land unit and rock sensitivity to erosion methods and was the least for image interpretation and integrated layers methods. The greatest precision, therefore, was related to image interpretation and integrated layers methods. In general, working unit map of image interpretation was the best method for preparing soil erosion features map.