A simplified model to estimate soil water characteristic curve from basic soil properties for expansive soils

The Soil Water Characteristic Curve (SWCC) defines the relationship between soil water content and matric suction, serving as a fundamental tool in unsaturated soil mechanics. The gravimetric SWCC (w-SWCC) specifically expresses this relationship using gravimetric water content versus matric suction. Many researchers have proposed models to predict SWCC from easily measured soil properties. These models are based on indirect methods using easily measured soil properties. However, most of the available models are developed for soils in temperate regions where the physical properties and mineralogy properties are different from the tropical soils, so their application in tropical regions may be infeasible. This paper proposes a simplified set of models used to estimate the w-SWCC of Bahir dar city using basic soil properties. The basic soil properties of eighteen soil samples obtained from Bahir dar city were determined experimentally. w-SWCC data points of the soils were determined from pressure plate tests and were fitted with Fredlund and Xing model to determine fitting parameters. The obtained fitting parameters were correlated with the basic properties of soils through multiple linear regression analysis. A set of models of fitting parameters were established, considering the fitting parameters related to gravimetric soil water characteristic curve. The validity of the models was assessed using four soil datasets, which were not used in developing the models. The proposed models have a good estimation of w-SWCC when compared to the existing prediction models.