A new Analytical Method for Estimating Soil Moisture Characteristic Curve using Horizontal Infiltration Data in Soil Column

Quantitative knowledge of soil hydraulic properties such as the soil moisture characteristics curve (SMC) is crucial for flow and transport modeling supporting hydrologic and agricultural engineering. However، many laboratory and field methods are currently available for direct measurement of the soil hydraulic properties but، most or all of direct methods are too time consuming and costly. Thus developing of physically-based methods for predicting SMC is essential. In this study، an analytical method was developed to estimate Brooks-Cory model parameters using horizontal infiltration data. The new method was compared with Wang et al (2002) method. Sixteen soils with wide range of hydraulic properties were used to test the new method. The results showed that the new method estimates n and hd parameters smaller than those experimental values. Although، results showed that the new method properly predicts the measured SMC data. High coefficient of determination (R2=0. 93) and low root mean square error (RMSE =0. 03) confirmed the accurate predictability of new method. Mean RMSE of Wang et al (2002) method was 0. 049. Therefore، results indicated that the new method is more accurate than Wang et al (2002) method for predicting soil moisture characteristics curve. The sensitivity analysis indicated that، for a given soil، the accurately estimation of SMC depends mainly on sorptivity parameter.