Saturated hydraulic conductivity and textural heterogeneity of soils

Authors: GARCIA GUTIERREZ, CARLOS - Polytechnic University Of Madrid; Pachepsky, Yakov; MARTIN, MIGUEL - Polytechnic University Of Madrid

Submitted to: Hydrology and Earth System Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2018
Publication Date: 7/20/2018
Citation: Garcia Gutierrez, C., Pachepsky, Y.A., Martin, M.A. 2018. Saturated hydraulic conductivity and textural heterogeneity of soils. Hydrology and Earth System Sciences. 22(7):3923-3932.

Interpretive Summary: Ability to conduct water to large extent controls the soil’s ecological functioning and services. Saturated hydraulic conductivity is the parameter that characterizes this ability. This parameter is difficult and often impossible to measure in proper detail, and it is often estimated from other soil properties. Proportion of soil particles by their sizes is known to be one of controls of the saturated hydraulic conductivity. This distribution is typically presented as triplet of particle fractions having sizes of sand, silt, and clay. We hypothesized that defining different triplet of fractions may provide better estimates of the saturated hydraulic conductivity. We tested this hypothesis with more than 19,000 datasets from the United States, and found that indeed saturated hydraulic conductivity can be estimated more efficiently if other triplets of fractions are used, and the unevenness of the particle mass distribution between the fractions is accounted for. Results of this work are expected to be used by the wide range of engineering design and consulting professionals who use soil hydraulic properties to develop their products and recommendations.

Technical Abstract: Saturated hydraulic conductivity Ksat is an important soil parameter that highly depends on soil's particle size distribution (PSD). The nature of this dependency is explored in this work in two ways, (1) by using the Information Entropy as a heterogeneity parameter of the PSD and (2) using descriptions of PSD in forms of textural triplets, different than the usual description in terms of the triplet of sand, silt and clay contents. The power of this parameter, as a descriptor of Ksat and log Ksat, was tested on a database of >19K soils. We found coefficients of determination of up to 0.977 for log Ksat using a triplet that combines very coarse, coarse, medium and fine sand as coarse particles, very fine sand as intermediate particles, and silt and clay as fines. The power of the correlation is analyzed for different textural classes and different triplets. Overall, the use of textural triplets different than traditional, combined with IE, may provide a useful tool for predicting Ksat values.