Evaluation of two indirect methods to estimate soil water characteristic curve of loess soil

Soil water characteristic curve (SWCC) is one of important parameters for modeling waterflow and solutes transport. The method used for soil basic physical properties to estimate SWCC has been a hot research field in soil science. For evaluating the adaptation of two indirect methods —Arya-Paris（AP）method and Tyler-Wheatcraft（TW）method —to estimate SWCC of loess soil, 296 soil samples with particle-size distribution were analyzed, bulk density and SWCC data on the Loess Plateau. A modified Frelund (Fred3P) model was used to simulate particle-size distribution, and AP and TW methods were used to predict SWCC of 296 soil samples. Results show that AP method has better precision for SWCC than TW method. At the same time, the soil texture has less effect on the prediction of AP model than TW method.