Conversion of the Modified Kovács Model Parameters to the Brooks and Corey and van Genuchten Model Parameters for the Water Retention Curve of Sandy and Silty Soils

Abstract

The modified Kovács (MK) model is a versatile and practical tool to estimate the water retention curve (WRC) of soils from their basic properties. However, the MK model has not yet been introduced in many codes or analytical solutions; most applications rather use the Brooks and Corey (BC) and/or van Genuchten (vG) formulations to express the WRC. The authors propose in this paper a direct conversion of the MK model parameters to the BC and vG equations parameters for sandy and silty materials. The proposed equations were developed using data from 15 types of sandy soils and 14 low-plasticity silts and validated using 16 other soils. The results presented in this paper indicate how the BC and vG equations parameters can be successfully predicted from the MK model parameters. The conversion procedure provides a practical means to estimate the WRC from the basic geotechnical properties of soils and to express this curve using three different mathematical formulations: MK, vG, and BC. These expressions allow obtaining a rapid estimation of the BC and vG model parameters that are frequently used in analytical solutions and commercial numerical codes to simulate unsaturated soil water flow.