The Determination of the Best Models to Estimate the Infiltration in Various Land uses for Optimum Management of Watersheds (Case Study: Kakasharaf Watershed, Lorestan Province)

The process of infiltration is one of the most important components of the hydrological cycle. On the other hand, the direct measurement of infiltration process is difficult, time spending and expensive. Infiltration models play a main role in managing water resources. Therefore, different types of models with various degrees of complexity were developed to reach this aim. So, this research carried out to the determination of the best infiltration estimation model in Rangeland, forest, agriculture land uses, in the Kakasharaf Watershed in Lorestan province. In this study, infiltration measurements were carried out using the infiltrometer double rings and Philip, Horton, Green-Ampt, Kostiakov and Soil Conservation Service of America (SCS) models, and use to estimate the infiltration. The results of this study showed that in rangeland use, the infiltration of all parameters (cumulative infiltration, the final infiltration rate, infiltration rate and the average time until stabilizing infiltration), is less than forestry and agriculture land use. It also compares the models, in the rangeland, Soil Conservation Service Model, with Nash-Sutcliffe efficiency coefficient 0.910 and coefficient of 0.915, and in land use of forest and agriculture, Philip Model with Nash efficiency coefficient, respectively 0.850 and 0.784, were selected as the best models in the three land uses. The Horton model was selected the weakest model in all of the three land uses as well.