The Determination of Infiltration in Various Land uses in Marghmalek and Shahrekord Watersheds

OOne of the most important hydraulic parameters affecting soil quality is the infiltration of water into the soil. That, the direct measurement of infiltration process is difficult, time spending and expensive. Infiltration models play the main role in managing watershed. Therefore, it is necessary to study different infiltration models in order to compare and achieve the best infiltration model in the area. This research determined the best infiltration estimation model in the pasture, garden, agricultural land uses (in two textures of silty clay loam and clay loam), in the Charmahal and Bakhtiari province. In this study, infiltration measurements were carried out using the infiltrometer single ring (to the inner diameter 35 cm). The initial humidity measured were respectively in pasture land use in silty clay loam and clay loam tissues (3.71, 4.27), in garden land use (2.18, 3.46) and, in agriculture land use (1, 2.25). and then infiltration models of Philip, Kostiakov and Soil Conservation Service of America (SCS), used and thus evaluated by the coefficient of determination (R2), Nash-Sutcliffe sufficiency score (NSSS), root mean squared error (RMSE) and mean error (ME). The results of this study showed that in rangeland use, the infiltration of all parameters (cumulative infiltration, the final infiltration rate and infiltration rate), is less than the garden and agriculture land use. It also compares the models, in the rangeland, but Kostiakov Model was accepted as the appropriate model in the garden, pasture and agricultural land use (in two soil texture), by Nash-Sutcliffe efficiency coefficient 0.99 and R2 (0.99) and a smaller error than other models. The next good models that had high efficiency were the Philip model by Nash-Sutcliffe efficiency coefficient and (R2=0.99) and an error of (0.15) in garden land use in silty clay loam texture, and the SCS model in pasture land (in SCL texture) with an error of 0.18.