A simple method of estimating soil-water characteristic curve using point pedotransfer functions

Abstract

The soil-water characteristic curve (SWCC) is an essential property in unsaturated soil mechanics. The test methods to determine SWCC are mainly adopted or adapted from either soil science or agriculture. Determining the SWCC is very labour intensive and time-consuming. Hence, many pedo-transfer functions (PTFs) for SWCC were developed in soil science and agriculture. The PTFs can be grouped into point and parametric PTFs. The point PTFs give the water contents at several suctions while the parametric PTFs give the values of the parameters in SWCC equations. The suctions commonly used in point PTFs are 4 (or 3), 10, 33, 100 and 1500 kPa. In this paper, a simple method is proposed to estimate unimodal SWCC using an ensemble of point PTFs. The proposed method is illustrated using six coarse-grained and six fine-grained soils from literature. The results show that the proposed method is able to estimate a unimodal SWCC with good accuracy.