Modeling soil shrinkage curve across a wide range of soil types

Knowledge about soil shrinkage improves the understanding and prediction of unsaturated hydraulic properties in nonrigid soils. Until now, there is no general model available, which is widely accepted and applied to quantify soil shrinkage curves. The objectives in this present paper are (i) to propose a new and simple model and to test it with a wide range of soil types; (ii) to mathematically distinguish the shrinkage zones; and (iii) to evaluate probable physical meaning of its parameters. The results show that the modified van Genuchten water retention curve model fits the data obtained from Reeve and Hall's six soils, Talsma's three soils and three Typic Chromexert' soils well and the correlation coefficients in the tested 12 soils are always higher than 0.995. The different shrinkage zones defined by the mathematical method agree well with actual soil shrinkage curve. The proportional shrinkage zone accounts for 30.9 to 79.9% of the total water loss and 63.5 to 93.9% of the total volume decrease, while the zero shrinkage zone only accounts for < 2.7% of the total volume decrease. The alpha, n, and m parameters of the modified van Genuchten model control soil shrinkage curve.