Designs for Disc Permeameters

TLDR

Disc permeameters are designed to measure hydraulic properties of field soils containing macropores and preferential flow paths, making them especially useful for soil management studies. The study presents designs for disc permeameters that operate under both positive and negative water supply heads. It evaluates membrane and soil contact effects on permeameter performance using quasi‑analytic flow solutions, addresses air‑entry limitations with design criteria, and demonstrates in‑situ tests of early infiltration stages and sorptivity variation with supply potential. The analysis yields criteria for selecting membrane and soil contact materials and uses in‑situ sorptivity measurements to estimate saturated hydraulic conductivity and the flow‑weighted mean characteristic pore dimension of a field soil.

Abstract

Abstract Disc permeameters are designed to measure hydraulic properties of field soils containing macropores and preferential flow paths and are particularly useful in soil management studies. We present here designs for disc permeameters for both positive and negative water supply heads. The effects of the water supply membrane and soil contact material on permeameter performance are examined using approximate quasi‐analytic solutions to the flow equation. This analysis provides approximate criteria for the selection of membrane and soil contact materials. Limitations to performance caused by restricted air entry are considered and design criteria are given also. We present in situ tests of the disc permeameter for the early stages of one‐dimensional infiltration and an example of the deterministic variation of sorptivity of a field soil with supply potential. Finally, we use ponded and unsaturated sorptivities measured in situ with disc permeameters to find the saturated hydraulic conductivity and flow‐weighted mean characteristic pore dimension of a field soil.