Application of a water infiltration model for simulating water
repellency of humus soil
Abstract
One-dimensional infiltration experiments were conducted using
hydrophilic and water-repellent soils from the Guishui River Basin to
study the effects of soil water repellency on cumulative infiltration
(CI) and the infiltration rate (IR). The test results show that, for the
hydrophilic soil (HS) sample, CI increases monotonously with time and IR
decreases monotonously. For the
water-repellent soil (W-RS),
however, the following characteristics were observed: (1) There is an
inflection point in CI and a sudden increase in IR. Larger values of the
initial soil water content produce an earlier and more significant
inflection point in CI, and a larger peak value of IR. (2) The post-peak
stable IR is greater than the pre-peak value, ignoring the beginning of
rapid infiltration, and the overall IR presents a single
peak. The applicability of various
water infiltration models was analyzed for the two soil types. Numerical
analysis suggests the following conclusions: (1) For both HS and W-RS,
the Kostiakov function, Gamma function, and Beta function (BF) models
exhibit good applicability. (2) For W-RS, the Gauss function model not
only reflects the monotonous decrease in IR, but also produces a steady
IR in the initial stage, a gradual increase before the peak value, and a
gradual decrease after the peak value. Similarly, the BF model reflects
the monotonous decrease in IR. A piecewise BF reproduces the U-shaped
change in rapid infiltration before the inflection point, as well as the
gradual increase and right-skewed distribution curve of W-RS
infiltration before and after the inflection point. The BF model
achieves the best simulation accuracy and has the widest applicability.
KEYWORDS Soil water repellency; Water infiltration model; Single peak;
Probability Density Function