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Russo 1996
Russo, D. (1996). A note on nonergodic transport of a passive solute in partially saturated anisotropic heterogeneous porous formations. Water Resources Research 32: doi: 10.1029/96WR02669. issn: 0043-1397.

First-order analysis, based on a stochastic continuum presentation of the Eulerian velocity in a partially saturated porous formation and a general Lagrangian description of the transport, was used to investigate the effects of a few length scales, characteristics of the heterogeneous transport domain, on nonergodic transport of passive solutes and its tendency to ergodic transport in steady state, gravity-dominated, unsaturated flow. Results of the analyses show that, as in ergodic transport, for given finite travel time, t, and fixed length-scale of the planar input zone, l, the principal components of the scaled macrodispersion tensor, Dij' (i,j=1,2,3), are controlled by the length-scale ratios &rgr;=Iyh/Iy&ugr; and &eegr;=&lgr;/Iyv, where Iyv and Iyh are the length scales of the formation heterogeneity in the vertical and the horizontal directions, respectively, and &lgr; is the macroscopic capillary length-scale. The results, that for fixed Iyv and given &rgr;, &eegr;, and t, the principal components of Dij' are controlled by the ratio l'=l/Iyh, and that they may reach their ergodic limits if l' is sufficiently large, are in agreement with results of previous studies of nonergodic transport in aquifers. New findings obtained in the present investigation suggest that when the mean unsaturated flow is vertical and the typical travel distance is small compared with the travel distance required for the plume to reach its asymptotic, Fickian behavior, the tendency of the principal components of the preasymptotic Dij' to their ergodic limits is enhanced by increasing &rgr; (larger stratification) and decreasing &eegr; (coarser-textured soil material). The effects of both &rgr; and &eegr; on the tendency of the transport to its ergodic limit, however, decrease with increasing travel time and vanishes at the large time limit, in which the transport approaches Fickian behavior. ¿ American Geophysical Union 1996

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Abstract

Keywords
Hydrology, Unsaturated zone
Journal
Water Resources Research
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Publisher
American Geophysical Union
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