Wavelet coherency analysis to relate saturated hydraulic properties to soil physical properties

Abstract

[1] A soil property may be related to another and the relationships may change depending on the scale and location. Understanding these scale- and location-dependent relationships is important for prediction of one soil property based on another. The objective of this study is to use wavelet coherency analysis to examine whether the relationship between hydraulic properties and soil physical properties are scale- and location-dependent. Undisturbed cores were collected along a transect from the sandy loam soil of a farm field in northern Saskatchewan, Canada. Saturated hydraulic conductivity (Ks), sand content, and organic carbon content (OC) were measured on these cores, and their relationships as a function of scale and location were analyzed using wavelets. Results indicated that the wavelet coherency between Ks and sand content is only significantly different from that of red noises at the scales around 48 m. The cross-wavelet spectrum and wavelet coherency are predominantly in phase, suggesting a positive correlation between Ks and sand. For Ks and OC, significant coherency exists at scales from 30 to 48 and around 80 m. At the scales of 30-48 and around 80 m the relationships are predominantly out of phase, suggesting negative correlation. Therefore relationships between Ks and sand or K s and OC are not only scale-dependent but also location-dependent. Scale and location dependence have an important implication for understanding the scaling relationships between Ks and sand and OC and for the prediction of Ks from sand and OC. Copyright 2005 by the American Geophysical Union.