Investigating the erosion in the geomorphologic facies and its relationship with drainage density

Soil erosion prediction, qualitatively and quantitatively, is very important to watershed managers and decision-makers. In this paper BLM method is used to evaluate erosion qualitatively. Since BLM is also used in PSIAC and MPSIAC methods to evaluate eighth and ninth factors, using this method should be in combination with geomorphology methods. Also, relationship between erosion and drainage density was studied using regression analysis. Sarvelayat Drainage Basin is located on the north of Sabzevar-Mashhad road, with an area of about 35,300 hectares. Base maps of the slope, aspect, altitude, lithology were prepared and aerial photos were interpred, geomorphology facieses were developed. The results show a correspondence between of BLM and Geomorphology methods in studying geomorphology facieses. Furthermore, in the BLM method drainage pattern factor is very complicated to be ranked by experts. To remove this difficulty, in this paper, statistical test of relation between erosion and drainage density in geomorphology facieses was accomplished. The findings of the study indicate that there is a significant positive correlation (99%) between two variables.