Susceptibility of soils to preferential flow of water: A field study

Abstract

Flow pathways of water and solutes in soils form distinct patterns, which are not a priori predictable. Macropore structure is a prime cause, but other factors, such as differing initial or boundary conditions, may also predispose a soil to produce bypassing of infiltrating water. This study was conducted to assess the flow pathways of water in different soils and to investigate the effect of initial water content on the flow pattern. Dye‐tracing experiments were carried out at 14 different field sites. The sites represent a good portion of soils used for agricultural crop production in Switzerland. Each site consisted of two 1.4 by 1.4 m plots, one of which had been covered with a plastic roof for two months before the experiment to achieve different initial water contents. Forty millimeters of water containing the dye Brilliant Blue FCF (C.I. Food Blue 2) were applied within 8 hours onto the plots with a sprinkling apparatus. One day after irrigation the plots were excavated, and the stained pattern was examined on a vertical 1 by l m soil profile. The spatial structure of flow patterns showed remarkable differences. In most soils, water bypassed the soil matrix. In some soils, dye penetrated beyond l m depth, whereas in others it remained in the top 50 cm. Structured soils were more prone to produce bypass flow, deep dye penetration, and pulse splitting than nonstructured soils. The initial water content had a less pronounced effect in some soils and no effect in others.

Estimation and upscaling of dual-permeability model parameters for the transport of E. coli D21g in soils with preferential flow

“…The occurrence of preferential flow is found to be the rule rather than the exception in most field soils (Flury et al, 1994;Singh and Kanwar, 1991), which may occur as a result of plant roots, burrowing earthworms, cracks, or natural structural heterogeneities (Beven and Germann, 1982;Cey et al, 2009;Madsen and Alexander, 1982;Unc and Goss, 2003;Wollum and Cassel, 1978). Preferential flow has been identified as a major problem hampering accurate predictions of contaminant transport in soils because of difficulty in quantifying the physical and chemical complexities of the soil matrix and macropore system (Šimůnek et al, 2003).…”

Lateral solute mixing processes — A key for understanding field-scale transport of water and solutes

“…Examples of such tracer distributions are shown in Roth et al (1991), Ritsema and Dekker (1993), and Flury et al (1994).…”

Hydrological and water-use efficiency implications of geomorphological stratification in palæochannels in the Northern Murray–Darling Basin

“…The draining water also leaches and transports salts and possible agrochemicals as shown previously through geophysical investigation (Yoder et al 2001) and direct sampling of soil water (Gunawardena et al 2011;Weaver et al 2013). Hydrologically, this means that palaeochannels are preferential flow paths in the landscape possibly providing rapid fluxes of water and chemicals to the catchment outlet in the same way as in soil profiles (Flury et al 1994). It is conceivable that over time, ecological groundwater-dependent communities have developed that rely on the water in these channels.…”