Integration of Hard and Soft Data to Characterize Field‐Scale Hydraulic Properties for Flow and Transport Studies

Field‐scale flow and transport studies are frequently conducted to assess and quantify various environmental and agricultural scenarios. The utility of field‐scale flow and transport studies, however, is frequently limited by our inability to characterize the heterogeneous distribution of hydraulic properties at these sites. In this study, we present an integrated approach, using both “hard” and “soft” data sets of field and laboratory scales in conjunction with pedotransfer functions, interpolation algorithm, and numerical modeling to characterize the hydraulic properties of the vadose zone. The approach is demonstrated at two 5‐ by 5‐m field plots selected for research on the transport and fate of nutrients and pathogens. We used hard data to quantify the magnitude of the hydraulic properties at selected locations in these plots and included laboratory and field measurements of the hydraulic properties from undisturbed cores and the instantaneous profile method, respectively. More abundant soft data included inductive electromagnetic readings and approximate particle‐size distribution information. The nearest neighbor interpolation algorithm was used to generate a heterogeneous realization of the saturated hydraulic conductivity on these plots. Numerical modeling of steady‐state water infiltration and redistribution experiments was used to compare laboratory‐ and field‐scale hydraulic properties and to refine our conceptual model of the vertical and lateral flow at this site. Good agreement between simulated and measured water contents and water pressure heads was obtained, indicating that field‐scale hydraulic properties were accurately quantified for these conditions. This article provides a real‐world example of how to combine information and approaches to tackle the difficult challenge of characterizing the hydraulic properties at a field site.