Modeling Soil Water Dynamics with Time-Variable Soil Hydraulic Properties

A. Schwen[1], G. Bodner[2], A. Schnepf[3], D. Leitner[3], G. Kammerer[1], and W. Loiskandl[1]

[1]Institute of Hydraulics and Rural Water Management, Univ. Natural Resour. Appl. Life Sci., BOKU, Wien, Austria
[2]Institute of Agronomy and Plant Breeding, Univ. Natural Resour. Appl. Life Sci., BOKU, Wien, Austria
[3]Institute of Soil Science, Univ. Natural Resour. Appl. Life Sci., BOKU, Wien, Austria
Published in 2009

Modeling soil water dynamics requires an accurate description of soil hydraulic properties, i.e. the retention and hydraulic conductivity functions. Generally, these functions are assumed to be unchanged over time in most simulation studies. In this paper, we implemented temporal changes in the soil hydraulic properties in a Richards’ equation simulation of soil water dynamics. Based on repeated measurement data of the soil water retention curve over a vegetation period, we compared the impact of using constant vs. temporally changing hydraulic functions on water flow simulation for different tillage methods. We observed distinct differences in the soil water content between the simulations for all tillage methods. The results show the remarkable effect of time-variable retention parameters on the soil water dynamics for tilled and non-tilled top soils.

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