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Soil hydraulic and transport properties

We determine soil hydraulic properties using soil columns where the water potential at the lower boundary of the samples and the water flux at the upper boundary can be controlled automatically. The water retention characteristics and hydraulic conductivity function are obtained based on the measured outflow dynamics of water (Multi-Step Outflow). The same device is used for measuring transport properties based on break-through curves of solutes.
The figure shows a sketch of the device together with typical results of a multi-step outflow experiment with controlled boundary conditions (red dashed), cumulative outflow (blue) and tensiometer readings (red). Black lines represent the modelled results based on Richards Equation after inverse parameter optimization for the hydraulic properties.
Actual research is focused on new parametrizations of hydraulic properties including hysteresis during infiltration and drainage processes. This is important to understand the redistribution of water into soil storage, deep infiltration along preferential flow paths, and surface runoff which is critical to predict the effect of changing precipitation patterns.

Selected publications

Weller, U., Ippisch, O., Köhne, J.M. and Vogel, H.-J.,2011: Direct measurement of
unsaturated hydraulic conductivity in soil including temporal dynamics, hydraulic
non-equilibrium and hysteresis, Vadose Zone Journal, 10:654–661.

Vogel, H.-J., Ippisch, O. 2008: Estimation of a critical spatial discretization limit
for solving Richards Equation at large scales, Vadose Zone Journal, 7, 112–114.

Vogel, H.-J., Ippisch, O. 2008: Estimation of a critical spatial discretization limit
for solving Richards Equation at large scales, Vadose Zone Journal, 7, 112–114.

Ippisch, O., Vogel,H.-J., and Bastian P. 2006: Validity limits for the van Genuchten–-
Mualem model and implications for parameter estimation and numerical simulation,
Adv. Water Res., 29, 1780-1789.

Vogel, H.-J., Ippisch, O. 2007: Estimation of a critical spatial discretization limit for solving Richards Equation at large scales, Vadoze Zone Journal, in press.

Ippisch, O., Vogel,H.-J., and Bastian P. 2006: Validity limits for the van Genuchten–\-Mua\-lem model and implications for parameter estimation and numerical simulation, Adv. Water Res., 29, 1780-1789.

Bayer, A., H. -J. Vogel, O. Ippisch and K. Roth 2005: Do effective properties for unsaturated weakly layered porous media exist? An experimental study, Hydrol. Earth Syst. Sci, 9, 517–522.