X-ray attenuation techniques to explore the dynamics of water in porous media

The flow of water in an unsaturated porous medium is described by Richards' equation. It is based on the assumption that the air in the pores is arbitrarily mobile and able to disappear from the pore space at any time. To solve Richards' equation a parameterization of the relationship between the water content and the matric potential is necessary: the soil-water characteristic. There are several models that describe this curve. Their parameters are typically determined from dynamic outflow experiments. A experimental setup was designed, that allows measurements of X-ray attenuation data and tomographic images during the outflow experiment. With this setup experiments were done to test the validity of Richards' equation for different boundary conditions. Therefore, the measured vertical distribution of water was compared with simulated distributions. The differences found show that the continuity of the air phase is not given at all points, and heterogeneity may prevent the determined effective parameters from being objective. Additionally, methods are introduced to analyze the rough internal structure of samples using X-ray computed tomography.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2005

Author dc:creator

• Bayer, Andreas

Contributors dc:contributor

• Roth, Kurt

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/5629

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:5629