Surface Measurements Of Hydraulic Properties In An Irrigated Soil Using A Disc Permeameter
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A. Comegna, G. Severino & A. Sommella
With a view to determining in situ the hydraulic properties of soils with macropores, disc permeameters are currently used which allow evaluation over time of water infiltration values and selective activation of preferential flow paths through variation in water supply potential imposed on the soil surface. It is then possible, through the resolution of wetting 3-D flow fields, to obtain soil hydraulic characteristics at or near saturation. In this study two different methods to calculate the hydraulic conductivity of a structured soil, based on disc-permeameter data, are compared. Laboratory core measurements based on the crust method are also used in the comparison. The first method based on a single disc at the same location with multiple water supply potentials gave results that are accurate, whereas the second method based on a single disc at different locations and water supply potentials gave biased values. The advantage of the examined equipment and procedures is that they are simple to apply and use. Moreover, useful applications of disc-permeameter techniques also consist in the measurement of soil structural parameters, especially pore size and areal macroporosity under irrigation practice. Keywords: 3-D infiltration, disc permeameter, unsatured flow parameters. 1 Introduction In recurrent open field situations, above all in soil surface layers, structural and textural variations as well as various geometric characteristics of the matrix may entail significant space-time variations in the processes of water and solute movement. The action of raindrops, the boundary forces provoked by surface flows and chemo-physical factors linked to water quality may, on the soil surface, lead to
3-D infiltration, disc permeameter, unsatured flow parameters.