Physically based soil water characteristic curves function for soils with inner porosity

ABSTRACT

Many unimodal models have been developed to describe the soil water characteristic curves (SWCC). However, for soils with inner porosity the independent draining of the structural and matrix pores frequently results in two distinct air-entry values, which any single unimodal function does not reproduce adequately. In the presented study, a bimodal lognormal (BLN) SWCCs function have been developed for soils with inner porosity. The model involved two overlaying continua pore systems, the pore probability density functions of systems were assumed as lognormal distribution and them can be superposed to obtain the overall probability density function of the soil. The experimental SWCCs data were used to verify the proposed method. The fitted result showed that the BLN approach resulted in the best agreement between measurement and simulation (R² > 0.99, RSME < 0.66). Another advantage of proposed function was capable of simulating bimodal SWCC using parameters which can be related to physical properties of the structural soils. These physically based parameters could more intuitively analyse the measured data. The BLN approach can potentially be used as effective tool for identifying mechanical and hydraulic porosities in the structural mediums.

KEYWORDS:

• Inner porosity
• pore probability density function
• lognormal distribution
• soil water characteristic curves

Acknowledgments

Blinded for anonymous review.

Disclosure statement

We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. We also confirm that we have given due consideration to the protection of intellectual property associated with this work and that there are no impediments to publication, including the timing of publication, with respect to intellectual property. In so doing we confirm that we have followed the regulations of our institutions concerning intellectual property.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51478197,51679093,51774147];Grant-in-Aid for Scientific Research (A) Ministry of Education, Culture, Sports, Science and Technology, Japan [22246064].