Critical Review on the Parameters Influencing Soil-Water Characteristic Curve

Abstract

The knowledge of unsaturated soil is indispensable for several hydrological and geoenvironmental problems such as permeation of water through vadoze zone, ground water recharge, and deciding irrigation requirements for crops. The accuracy of these studies depends on the precise characterization of unsaturated soil, which includes the development of the soil suction–water content relationship (SWR) or soil–water characteristic curve (SWCC). It is believed that each soil has a unique SWCC. However, past studies clearly indicate that there are different parameters that would influence the uniqueness of the SWCC. Therefore, the present study purports to critically review the findings reported in the literature to reveal the influence of different parameters on the SWCC. The review is divided into two sections. The first section deals with those parameters that need a critical assessment, and the second section deals with apparent factors that influence the SWCC. The critical evaluation brings out the anomalies associated with the influence of some of the parameters, such as compaction state, measurement procedures, stress history, and range of suction measurement on the SWCC. Compaction water content has a more significant influence on the SWCC than density. The SWCC is found to be unique at a high range of soil suction for which adsorptive forces are predominant. It was found that the extent of influence of parameters on the SWCC is soil specific. However, further experimental investigations are required to quantify soil-specific parametric influence on the SWCC.