A general procedure for modeling one-dimensional unsteady water flow through unsaturated swelling soil has been developed. The generalized equation is based on Richards' <1931> equation for unsaturated flow. The developed equation and its numerical solution used in the procedure can be applied to the study of soil drainage and redistribution where the flux of water is downward toward the water table. In this case the water content at each point in the profile decreases with time. The derivation of the relationship between volume changes and corresponding water losses reflects the effect of different shrinkage phases for a clayey soil. The model partitions the soil into two domains: macropores and micropores. To verify the model, results are compared with two other models. The model is then applied, using Regina clay as a media, to demonstrate the effect of volume change on moisture profiles during drainage. The results demonstrate that errors will occur if the classical theory of water movement in a nonswelling soil is employed to describe water flow in an unsaturated soil that exhibits volume change during wetting and drying. ¿ 2000 American Geophysical Union