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Soil air permeability facilitates its hydraulic permeability prediction


Reliable prediction of soil hydraulic characteristics is often required to assess soil and ground water contamination risk or soil remediation activities. Soil permeability to water either in saturated or unsaturated zones is one of the most important hydraulic characteristics. Direct measurement of soil permeability to water or hydraulic conductivity is the most reliable approach to characterize it. However, its direct measurement, either in the laboratory or the field, is time consuming and requires significant human intervention. Therefore, soil scientists have attempted to develop several indirect approaches to predict soil permeability to water using its readily available properties. Soil air permeability is one of the its most appropriate readily available properties in this regard.

In the November–December 2016 issue of the Soil Science Society of America Journal, researchers introduce a semi-theoretical equation to predict soil water permeability to water in unsaturated zone using its air permeability as a predictor. 

First, the team modeled soil air permeability by considering a similar phenomenon between water and air flows in soil medium. Then, the researchers theoretically linked soil air permeability to its unsaturated hydraulic conductivity. Finally, they tested the proposed model using laboratory-measured data to check its accuracy. The accuracy check showed that the proposed model can predict unsaturated hydraulic conductivity of soil with an average evaluation error of 4%, illustrating reasonably high accuracy for the model.

Regarding the fast and nondestructive measurement of soil air permeability compared with its unsaturated hydraulic conductivity, the proposed model seems to be more practical to characterize unsaturated soil hydraulic conductivity and can improve the accuracy and efficiency of unsaturated soil hydraulic conductivity estimation.

Read the full paper in SSSAJ. Free preview Jan 30 - Feb 6