Presentation of a comprehensive method for determining erodibility rate of rock units with a review on Iranian geology

One of the most important problems that empirical model users in Iran are facing with, is that these models are prepared for countries with special conditions such as lithology factor, which scores are given based on geology condition of origin country that are not compatible for a vast country like Iran with a great lithological variation. This research was conducted to reduce such problems and increase the efficiency and localization of these kind of models and provides rock erosion sensitivity factor for their special conditions. In PSIAC and EPM as a common experimental models, lithology factor is an important agent among other effective factors. In this research, a comprehensive classification of erodibility has been produced in 10 orders, based on mineralogy, chemistry, texture, structure and mechanical properties. Regarding to aridity of many parts of the country, and low rate of soil generation, erodibility rates of geological formations would be an important tasks. Results showed that, about 70 percent of the area covered with very low to low strength lithology to erosion and have a high potential of sediment yielding. Geological formations’ erodibility has been classified in 30 Tamab watershed with order of 4 and the results are compared with EPM results and monitored values in river gauging stations. Results also indicated a good agreement with high confidence with natural conditions and with respect to other important factors of the watersheds such as topography and rainfall.