Multi-functional heat pulse probe measurements of coupled vadose zone flow and transport

• Published in: Advances in water resources Vol. 29; no. 2; pp. 250 - 267
• Main Authors: Mortensen, Annette P., Hopmans, Jan W., Mori, Yasushi, Šimůnek, Jirka
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2006
• Subjects: Dispersion; electrical conductivity; Heat pulse probe; heat transfer; Heat transport; probes (equipment); soil transport processes; soil water content; soil water movement; Solute transport; solutes; Unsaturated flow; vadose zone; Vadose zone properties; Water content; Water flux; Heat pulse probe; Solute transport; Water content; Unsaturated flow; Vadose zone properties; Heat transport; Water flux; Dispersion
• ISSN: 0309-1708; 1872-9657
• DOI: 10.1016/j.advwatres.2005.03.017

Simultaneous measurement of coupled water, heat, and solute transport in unsaturated porous media is made possible with the multi-functional heat pulse probe (MFHPP). The probe combines a heat pulse technique for estimating soil heat properties, water flux, and water content with a Wenner array measurement of bulk soil electrical conductivity (EC bulk). To evaluate the MFHPP, we conducted controlled steady-state flow experiments in a sand column for a wide range of water saturations, flow velocities, and solute concentrations. Flow and transport processes were monitored continuously using the MFHPP. Experimental data were analyzed by inverse modeling of simultaneous water, heat, and solute transport using an adapted HYDRUS-2D model. Various optimization scenarios yielded simultaneous estimation of thermal, solute, and hydraulic parameters and variables, including thermal conductivity, volumetric water content, water flux, and thermal and solute dispersivities. We conclude that the MFHPP holds great promise as an excellent instrument for the continuous monitoring and characterization of the vadose zone.