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United States Department of Agriculture

Agricultural Research Service

Title: Analysis of Solute Redistribution in Heterogeneous Soil: I. Geostatistical Approach to Describe the Spatial Scaling Factors

Authors
item Jacques, D - INST - LAND & WATER MGMT
item Vanderborght, J - INST - LAND & WATER MGMT
item Mallants, D - INST - LAND & WATER MGMT
item Mohanty, B - U.C. RIVERSIDE
item Feyen, J - INST - LAND & WATER MGMT

Submitted to: Geostatistics and Quantitative Geology
Publication Type: Book / Chapter
Publication Acceptance Date: October 15, 1996
Publication Date: N/A

Interpretive Summary: The soil water retention curve (WRC) and the saturated hydraulic conductivity (Ks) are important physical properties for water flow and contaminant transport in the subsurface environment. In a multi-layered soil, field-scale spatial variability of WRC and Ks data was described by two sets of scaling factors using similar media scaling approach. These scaling factors were characterized by log-normal distribution, stationary variances, and nonstationary medians. Median-polishing schemes were adapted to clean up the data for further spatial analyses. We found that spatial structures of both the scaling factors were mostly due to large- scale variations because of soil depositional pattern or crop production and occurred at two mutually-exclusive horizons. Our findings can be useful in creating simulated parameter-fields for water flow and contaminant transport modeling.

Technical Abstract: The soil water retention curve (WRC) and the saturated hydraulic conductivity (Ks) were measured in three overlying horizons in a vertical soil profile. The spatial variability in WRC and Ks was described with two separate sets of scaling factors, i.e., alpha (psi) and alpha (k) for WRC and Ks, respectively. Both sets of scaling factors were found to be lognormally distributed. The log transformed scaling factors exhibited stationarity in their variance but showed non- stationarity in their median, both in vertical and horizontal direction. The trends or large scale deterministic variations were successfully removed using a median polish algorithm. The large scale variations contributed significantly to the total observed variability for the alpha (psi) parameters of the C2 horizon and for the alpha (K) parameters of the Ap horizon. Spatial structure for scaling parameters was only observed in these two cases, whereas a pure nugget was observed in all other cases.

Last Modified: 7/25/2014
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