Directions of preferential flow in a hillslope soil, 1. Quasi-steady flow

✍ Scribed by Peter F. Germann; Michael Zimmermann

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 258 KB
• Volume: 19
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.1506

✦ Synopsis

Preferred infiltration is mainly perceived as vertically down whereas subsurface storm flow is thought to occur parallel to slopes. The transition from vertical to lateral flow in a layered hillslope soil is the focus of the contribution. Transient flow is assumed to move as a wetting front. Three time-domain reflectometry (TDR) wave-guides, each 0Ð15 m long, were mounted in the shape of a truncated tetrahedron with its peak pointing down. Each wave-guide focuses the front velocity along its axis. The three front-velocity vectors are decomposed into their x, y and z components, which are then assembled to the resultant velocity vector. The volume density flux of preferred flow is the product of the front velocity and the mobile water content. The latter is the amplitude of transient soil moisture measured with each waveguide. The resultant vector of the volume flux density is computed similarly to the velocity vector. The experimental approach allows for the rapid assessment of transient flows without relying on the variation of water potentials. The experiments indicate that the directions of the resultant vectors of velocity and volume flux density can be estimated if the moisture variations of the three TDR wave-guides are strongly correlated during the passing of the wetting front.