Characterizing Preferential Flow Paths in Texturally Similar Soils under Different Land Uses by Combining Drainage and Dye-Staining Methods

Abstract

Preferential flow paths have been widely characterized by many visualization methods. However, the differences in preferential flow paths under various land uses and their relationships to hydraulic properties remain uncertain. The objectives of this study are to (1) characterize preferential flow paths under various land uses (forest and orchard) by combining drainage and dye-staining methods and to (2) build a connection between preferential flow paths and hydraulic-related parameters and extract the proportion of preferential flow paths from the compounding effects of matrix flow and preferential flow. The dye-staining experiments were conducted in five sandy soils and one sandy clay loam in situ, including four soils from forest and two soils from orchards. A total of 47 soil cores, 4 cm in height and 9 cm in diameter, were collected in each layer of the dye-stained soils for drainage experiments in the laboratory. Dye coverage and hydraulically equivalent macropore parameters (macroporosity, pore size distribution, and number of macropores) and their relationships were analyzed. The results show that the volume of preferential flow is partly affected by the total macropore volume. The effect of macropores on preferential flow varies by macropore size distribution. Dye coverage exhibited a significant (P < 0.01) correlation with macroporosity (correlation coefficient 0.83). Based on the value of macroporosity or steady effluent rates, the part of the dye coverage that was due to preferential flow on the surface dye-stained soil (resulting from both matrix and preferential flow) could be identified in this study. Compared with orchards, forestland has more preferential flow paths in both surface soil and subsoil. Further studies are needed to quantify the 3-D preferential flow paths and build a connection between preferential flow paths and hydraulic properties.

Modeling the Transport of Inorganic Arsenic Species through Field Soils: Irrigation and Soil Structure Effect

“…Although the brilliant blue dye has excellent visibility and low adsorption in soils [33], the adsorption differs with organic matter content and clay [49]. The use of dye to mark the PF paths in field soils is common [50,51].…”

Estimation of soil hydraulic and solute transport properties from field infiltration experiments

“…Physically-based modeling of coupled water and solute transport requires the knowledge of soil properties that have to be estimated with adequate accuracy. In this sense, the development of in situ methods to determine both the saturated and unsaturated hydraulic properties of the soil surface has received increasing attention in recent years, in particular, to assess the role of preferential flow pathways in soil management practices (Köhne, Schlüter, & Vogel, 2011;Legout, Legout, Nys, & Dambrine, 2009;van der Linden, Tordesillas, & Narsilio, 2019;Zhang, Cao, Hou, & Cheng, 2021).…”