Impact of initial and boundary conditions on preferential flow

Preferential flow in Soil is approached by a water-content wave, WCW, that proceeds downward from the ground surface. WCWs were obtained from sprinkler experiments with infiltration rates varying from 5 to 40 mm h(-1). TDR-probes and tensiometers measured volumetric water contents theta(z,t) at seven depths, and capillary heads, h(z,t) at six depths in a column of an undisturbed soil. The wave is characterized by the velocity of the wetting front, C(W), the amplitude, W(S), and the final water content, theta*. We tested with uni-variate and bi-variate linear regressions the impacts of initial volumetric water contents, theta(ini), and input rates, q(S), on C(W), W(S) and theta*. The test showed that theta(ini) influenced theta* and W(S) and q(S) effected C(W). The expected proportionality of W(S) approximate to qs(1/3) was weak and C(W) approximate to qs(2/3) was strong. (C) 2008 Elsevier B.V. All rights reserved.