Moisture profiles during steady vertical flows in swelling soils

Abstract

Practical working equations for describing numerically soil moisture profiles in homogeneous swelling soils during steady vertical flows were developed. These equations were solved on a computer with soil water and swelling curve data appropriate to Rideau clay loam, which was taken as a typical example of a swelling soil. Unsaturated swelling soils were shown to exhibit either xeric or hydric profiles for downward flows, whereas for upward flows they exhibit only a xeric profile, just as rigid soils do. On the other hand, saturated swelling soils were shown to have hydric profiles in the downward flow situation and either hydric or xeric profiles during upward flows. The overburden or ‘envelope pressure’ potential was shown to exert a great influence, in almost all circumstances, in reducing the maximum evaporative flow from a shallow water table in a swelling soil as compared to the equivalent nonswelling case.