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Title: Upscaling soil saturated hydraulic conductivity from pore throat characteristics

item GHANBARIAN, BEHZAD - University Of Texas
item HUNT, ALLEN - Wright State University
item Skaggs, Todd
item JARVIS, NICHOLAS - Swedish University Of Agricultural Sciences

Submitted to: Advances in Water Resources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2017
Publication Date: 3/18/2017
Citation: Ghanbarian, B., Hunt, A.G., Skaggs, T.H., Jarvis, N. 2017. Upscaling soil saturated hydraulic conductivity from pore throat characteristics. Advances in Water Resources. 104:105-113. doi: 10.1016/j.advwatres.2017.03.016.

Interpretive Summary: Crop growth and many other critical agricultural and ecological processes are dependent on the amount of water that exists in a soil. A key parameter that affects water drainage and retention in soil is the soil hydraulic conductivity. Information about soil hydraulic conductivity permits better planning and management of soil-water resources. In this work, we developed a model for predicating soil hydraulic conductivity based on knowledge of other soil parameters. We found that predictions were accurate to within a factor of 3, which is considered a high level of accuracy in this problem domain. The new predictive model will help engineers and researchers working to identify irrigation practices that improve the management of scarce water and soil resources.

Technical Abstract: Upscaling and/or estimating saturated hydraulic conductivity Ksat at the core scale from microscopic/macroscopic soil characteristics has been actively under investigation in the hydrology and soil physics communities for several decades. Numerous models have beendeveloped based on different approaches, such as the bundle of capillary tubes model, pedotransfer functions, etc. In this study, we apply concepts from critical path analysis, an upscaling technique first developed in the physics literature, to estimate saturated hydraulic conductivity at the core scale from microscopic pore throat characteristics reflected in capillary pressure data. With this new model, we find Ksat estimations to be within a factor of 3 of the average measured saturated hydraulic conductivities reported by Rawls et al. (1982) for the eleven USDA soil texture classes.