Pinhole multistep centrifuge outflow method for estimating unsaturated hydraulic properties with small volume soil samples

Long Thanh Bui, Yasushi Mori

Research output: Contribution to journalArticlepeer-review

Abstract

If soil hydraulic conductivity or water holding capacity could be measured with a small volume of samples, it would benefit international fields where researchers can only carry a limited amount of soils out of particular regions. We performed a pinhole multistep centrifuge outflow method on three types of soil, which included granite decomposed soil (Masa soil), volcanic ash soil (Andisol soil), and alluvial clayey soil (paddy soil). The experiment was conducted using 2 mL and 15 mL centrifuge tubes in which pinholes were created on the top and bottom for air intrusion and outflow, respectively. Water content was measured at 5, 15, and 30 min after applying the centrifuge to examine the equilibrium time. The results showed that pinhole drainage worked well for outflow, and 15 or 30 min was sufficient to obtain data for each step. Compared with equilibrium data, the retention curve was successfully optimized. Although the curve shape was similar, unsaturated hydraulic conductivities deviated largely, which implied that Ks caused convergence issues. When Ks was set as a measured constant, the unsaturated hydraulic properties converged well and gave ex-cellent results. This method can provide soil hydraulic properties of regions where soil sampling is limited and lacks soil data.

Original languageEnglish
Article number1169
JournalWater (Switzerland)
Volume13
Issue number9
DOIs
Publication statusPublished - May 1 2021

Keywords

  • Centrifuge method
  • HYDRUS
  • Inverse solution
  • Multistep outflow
  • Retention curve
  • Unsaturated hydraulic conductivity

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Biochemistry
  • Aquatic Science
  • Water Science and Technology

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