Nonmonotonic moisture profile as a solution of Richards' equation for soils with conductivity hysteresis

Abstract

Qualitative analysis of similar moisture profiles advancing in dry soils during the constant rate infiltration is proposed. The Richards partial derivative equation is reduced to the ordinary one, which is easily integrated. Using simple kinematic relations nonmonotonic saturation-depth profiles travelling both in 1D case and in 2D finger-type flows are interpreted as a consequence of hysteresis of conductivity depending on water content. The estimations made allow the description of fingering as a result of hysteresis. The mean velocity of hysteretic finger-type flow can be higher than velocity of 1D hysteretic flow while the last advances faster than the usual monotonic front without hysteresis. | Qualitative analysis of similar moisture profiles advancing in dry soils during the constant rate infiltration is proposed. The Richards partial derivative equation is reduced to the ordinary one, which is easily integrated. Using simple kinematic relations nonmonotonic saturation-depth profiles travelling both in 1D case and in 2D finger-type flows are interpreted as a consequence of hysteresis of conductivity depending on water content. The estimations made allow the description of fingering as a result of hysteresis. The mean velocity of hysteretic finger-type flow can be higher than velocity of 1D hysteretic flow while the last advances faster than the usual monotonic front without hysteresis.