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Tokunaga & Wan 2001
Tokunaga, T.K. and Wan, J. (2001). Surface-zone flow along unsaturated rock fractures. Water Resources Research 37: doi: 10.1029/2000WR900242. issn: 0043-1397.

Although fractures in rock are well recognized as pathways for fast percolation of water, processes which permit fast flow along unsaturated fracture pathways remain to be identified and understood. Earlier aperture-based models of flow in partially saturated fractures permit fast flow only through a continuous network of locally saturated segments. Film flow was recently identified as a mechanism capable of sustaining fast flow along truly unsaturated fractures when the matric potential is very close to zero. Another mechanism for fast flow along unsaturated fractures is introduced in this study, surface-zone flow, which can be important when the permeability of the rock along fractures (fracture skin) is significantly greater than that of the bulk rock matrix. In such systems the fracture surface zone provides low resistance pathways through which fast flow (relative to the bulk matrix rock) can occur, even when the fractures are at very low water saturation. Initial experimental tests of surface-zone fast flow were performed. Surface-zone fast imbibition of water was measured on a welded tuff and a rhyolite. However, because (1) imbibition rates are also strongly influenced by rock wettability, (2) these initially air-dry rocks exhibited finite contact angles upon exposure to water, and (3) we lack methods to reliably measure permeabilities of thin regions on rock surfaces, quantification of permeability contrasts was not possible in these initial tests. ¿ 2001 American Geophysical Union

BACKGROUND DATA FILES

Abstract

Keywords
Hydrology, Unsaturated zone, Physical Properties of Rocks, Fracture and flow, Physical Properties of Rocks, Permeability and porosity
Journal
Water Resources Research
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Publisher
American Geophysical Union
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