Bimodal and multimodal descriptions of soil-water characteristic curves for structural soils

Many empirical models have been developed to describe soil-water characteristic curves (SWCCs). Unfortunately, few functions adequately describe SWCCs of structured soils. In the presented study, a bimodal and a multimodal SWCCs functions have been developed for the purpose of studying unsaturated water flow and solute transport in structured soils. The model involves two or multiple overlaying continua pore systems, the pore probability density functions of systems are assumed as lognormal distribution and them can be superposed to obtain the overall probability density function of the soil. The proposed functions are capable of simulating bimodal or multimodal SWCCs using parameters which can be related to physical properties of the structural soils. After verification, we conclude that proposed function fit bimodal SWCCs very well. These models can potentially be used as effective tools for indentifying hydraulic porosities in the structural medium.