assessing the sensitivity of infiltration models to variability of soil moisture

abstract infiltration is one of the most important phenomena which is affected by the soil physical and hydraulic characteristics. measurement of infiltration needs the high cost and is time consuming, therefore estimation of infiltration is necessary. also, due to variability of soil moisture, it is important to determine the appropriate model for the estimating the infiltration rate. the present study was carried out for determining the sensitivity of infiltration models including kostiakov, philip, horton, soil conservation service (scs) and modified green – ampt models at different levels of the soil moisture. to consider the homogeneity of soil and slope, this research carried out in mour mouri region, of ilam province. in this study the infiltration rate was measured by using double ring infiltrometer in the prepared plats (1 m2) at four levels of soil moisture, including control (0), 5, 10 and 15 liters. afterward the best model was selected by some criteria of error assessment, such as percentage of relative error (re), root mean square error (rmse), modeling efficiency coefficient (ef) and coefficient of determination (r2). the results showed that generally, the kostiakov model can estimate the infiltration rate better than other infiltration models with increasing the soil moisture, the precision of horton model increased.