Ponding time, hydraulic conductivity, and sorptivity – experimental and numerical determination

Abstract

Determination of actual soil sorptivity becomes one of the research preferences in the field of soil management and flash-flood protection. This Note presents an innovative approach to soil sorptivity determination. A single ring infiltration method, along with a simulation of rainfall of constant intensity, was used to measure ponding time t p. Hydraulic conductivity K was approximated from the analysis of the time series of the process of vertical non-steady cumulative infiltration appearing after the ponding time. Based on Philip's infiltration theory, a simple equation was derived in order to calculate sorptivity S from ponding time, rainfall intensity, and saturated hydraulic conductivity. Numerically determined results of S show to closely correspond with theoretical values published in the literature. To the best of our knowledge, this process of numerical determination of K and S has not been published so far. Moreover, unlike the traditional methods, e.g. single or double-ring in filtration experiments, this method provides more precise and representative values of S, verified by ponding time, as the results refer to the original soil sorptivity, not the sorptivity determined after the ponding time (meaning sorptivity of the fully saturated environment) which tends to reach zero. Our assumption was definitely confirmed by field experimental determination of ponding time and selected soil hydrology characteristics.