TY  - GEN
A1  - Bayer, Andreas
TI  - X-ray attenuation techniques to explore the dynamics of water in porous media
N2  - 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.
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/5629/
AV  - public
KW  - X-ray attenutation 
KW  -  porous media 
KW  -  unsaturated zone 
KW  -  tomography 
KW  -  Richards-equaiton
ID  - heidok5629
Y1  - 2005///
ER  -