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Characterization of unsaturated zone hydrologic properties and their influence on lateral diversion in a volcanic tuff at Yucca Mountain, Nevada

The study of the subsurface flow and distribution of water is critical to the
evaluation of the unsaturated zone for a potential geologic high-level radioactive
waste repository. This site is located at Yucca Mountain, Nevada in the northern
Mojave Desert. and was chosen on the basis of its low precipitation, deep unsaturated
zone, and layered volcanic rocks providing the potential for natural hydraulic barriers
to reduce the downward percolation of water through the waste storage area. The
detailed characterization of hydrologic properties is necessary to evaluate the
mechanisms responsible for the distribution and flow of water in the unsaturated
zone. Analyses in this study have provided detailed hydrogeologic units with unique
hydrologic properties and hydraulic parameters. Porosity was determined to be a
useful physical property for predicting hydraulic parameters, as it relates to the largescale
deterministic processes that created the volcanic rocks. The detailed property
dataset, along with field measurements of moisture status, temperature, and
chemistry, were used to evaluate the potential for lateral diversion in the rocks above
the potential repository. It was determined that lateral diversion is a small-scale
process in this natural system. On the basis of analyses performed in this study, it is
suggested that large-scale diversion is not likely to occur at this site. This mechanism
should not, therefore, be relied upon to perform as a natural hydraulic barrier to flow
reducing percolation through the unsaturated zone. / Graduation date: 2002

Identiferoai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32771
Date19 February 2002
CreatorsFlint, Lorraine E.
ContributorsSelker, John S.
Source SetsOregon State University
Languageen_US
Detected LanguageEnglish
TypeThesis/Dissertation

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