HR: 0830h
AN: H21D-0864    [PDF]
TI: Scale Effects on the Hydraulic Conductivity: Real or Artifact?
AU: * Hunt, A G
EM: allenghunt@msn.com
AF: CIRES, University of Colorado, Boulder, Boulder, CO 80309 United States
AB: Field results for the hydraulic conductivity, K, often indicate that K increases with scale. This effect has been justified by appeal to the possibility that, with increasing scale, a) the connectivity of the highly conducting pathways increases, or b) that larger pores/fractures become accessible. The latter equates to a statistical bias in that the definition of the medium (and the porosity) become scale-dependent. For the former case, with one exception, it is not possible to connect sides of a medium at a large scale withoug having connections at a small scale too. If these highly conductive regions are properly weighted, it will be seen that K becomes either constant, or diminishes with scale. A noteworthy exception occurs in anisotropic systems, where more connections can be gained by increasing the system size than are lost. However, this effect is shown here to be more properly a dimensional effect, resulting from a cross-over from 1D conduction at small scales to 3D conduction at large scales. Appropriate upscaling would remove the effect, but field experiments cannot be configured to do so.
DE: 1829 Groundwater hydrology
DE: 1899 General or miscellaneous
SC: Hydrology [H]
MN: 2003 Fall Meeting