Quantifying water flow and retention in an unsaturated fracture-facial domain

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Abstract

Hydrologically significant flow and storage of water occur in macropores and fractures that are only partially filled. To accommodate such processes in flow models, we propose a three-domain framework. Two of the domains correspond to water flow and water storage in a fracture-facial region, in addition to the third domain of matrix water. The fracture-facial region, typically within a fraction of a millimeter of the fracture wall, includes a flowing phase whose fullness is determined by the availability and flux of preferentially flowing water, and a static storage portion whose fullness is determined by the local matric potential. The flow domain can be modeled with the source-responsive preferential flow model, and the roughness-storage domain can be modeled with capillary relations applied on the fracture-facial area. The matrix domain is treated using traditional unsaturated flow theory. We tested the model with application to the hydrology of the Chalk formation in southern England, coherently linking hydrologic information including recharge estimates, streamflow, water table fluctuation, imaging by electron microscopy, and surface roughness. The quantitative consistency of the three-domain matrix-microcavity-film model with this body of diverse data supports the hypothesized distinctions and active mechanisms of the three domains and establishes the usefulness of this framework.

Additional publication details

Publication type Book chapter
Publication Subtype Book Chapter
Title Quantifying water flow and retention in an unsaturated fracture-facial domain
DOI 10.1002/9781118877517.ch12
Year Published 2015
Language English
Publisher Wiley
Contributing office(s) National Research Program - Western Branch
Description 14 p.
Larger Work Type Book
Larger Work Title Fluid dynamics in complex fractured-porous systems
First page 169
Last page 182
Online Only (Y/N) N
Additional Online Files (Y/N) N