SFB 1313 Publication by Joseph Piotrowski

New SFB 1313 publication, published in MDPI Geosciences:

"Gas Permeability of Salt Crusts Formed by Evaporation from Porous Media"

Authors

• Joseph Piotrowski (Forschungszentrum Jülich, SFB 1313 research project C05)
• Johan Alexander Huisman (Forschungszentrum Jülich, SFB 1313 research project C05)
• Uri Nachshon (Ben-Gurion University of the Negev, Isreal)
• Andreas Pohlmeier (Forschungszentrum Jülich, SFB 1313 research project C05)
• Harry Vereecken (Forschungszentrum Jülich)

Abstract

Soil salinization in irrigated croplands is a key factor in soil degradation and directly affects plant growth and soil hydrological processes such as evaporation and infiltration. In order to support the development of appropriate irrigation strategies, it is important to understand the impact of salt crusts that form during evaporation from saline soils on water flow. The determination of the effective hydraulic properties of salt crusts that control evaporation is still a challenge due to the lack of suitable measurement techniques. In this study, we propose an approach using gas flow to determine the permeability of salt crusts obtained from evaporation of unsaturated saline solutions of three different salt types and investigate the impact of the crust permeability on evaporation. For this, sand columns saturated with initial solutions of sodium chloride (NaCl), magnesium sulfate (MgSO₄), and sodium sulfate (Na₂SO₄) at concentrations corresponding to 33% of the solubility limit were prepared and allowed to evaporate in order to induce crust formation. The results demonstrated that the intrinsic permeability of the dry salt crusts was similar for the different types of salts (≈ 4 x 10^-12 m²), whereas the evaporation of the prepared columns differed significantly. We conclude that the intrinsic crust permeability only partly explains the impact of the crust on evaporation. Other effective crust properties such as porosity or unsaturated hydraulic properties may provide additional information on how evaporation is affected by salt crust formation.