bimodal four-parameter lognormal linear model of soil water repellency persistence

• Published in: Hydrological processes Vol. 23; no. 6; pp. 881 - 892
• Main Authors: Regalado, C.M, Ritter, A
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 15.03.2009; Wiley
• Subjects: dynamic factor analysis; Earth sciences; Earth, ocean, space; Exact sciences and technology; Hydrology; Hydrology. Hydrogeology; hydrophobicity; lognormal distribution; Perls-Verhulst equation; repellency persistence; soil water content; three-parameter lognormal; water repellency model; WDPT test; Iberian Peninsula; Southern Europe; Europe; Spain; droplets; penetration; repellency persistence; dynamic factor analysis; linear models; infiltration; surface water; factor analysis; hydrophobicity; three-parameter lognormal; WDPT test; lognormal distribution; Perls-Verhulst equation; organic materials; water content; soil water content; water repellency model; soils; correlation coefficient; national parks
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.7226

Soil water repellency may be characterized in terms of the delayed infiltration time of a water droplet resting on the soil surface, which is, water drop penetration time (WDPT), or repellency persistence. Such repellency persistence varies nonlinearly with soil water content (θg), although no models have been proposed to reproduce the variation of WDPT with θg in soils. Dynamic factor analysis (DFA) is used to identify two common patterns of unexplained variability in a scattered dataset of WDPT versus θg measurements. A four-parameter lognormal distribution was fitted to both common patterns obtained by DFA, and these were combined additively in a weighted multiple linear bimodal model. We show how such an empirical model is capable of reproducing a large variety of WDPT versus θg curve shapes (N = 80) both within a wide range of measured WDPTs (0-17 000 s) and for samples with organic matter content ranging from 21·7 to 80·6 g (100 g)⁻¹. Copyright © 2009 John Wiley & Sons, Ltd.