Estimates of average annual precipitation (AAP) are-needed for hydrologic modeling at
Yucca Mtn., Nevada, site of a proposed, high-level nuclear waste repository. Historical
precipitation data and station elevation were obtained for stations in southern Nevada and
southeastern California. Elevations for 1,531 additional locations were obtained from
topographic maps. The sample direct-variogram for the transformed variable TAAP =
ln(AAP) * 1000 was fit with an isotropic, spherical model with a small nugget and a range
of 190,000 ft. The sample direct-variogram for elevation was fit with an isotropic model
with four nested structures (nugget, Gaussian, spherical, and linear) with ranges between 0
and 270,000 ft. There was a significant (p = 0.05, r = 0.75) linear correlation between
TAAP and station elevation. The sample cross-variogram for TAAP and elevation was fit
with two nested structures (Gaussian, spherical) with ranges from 55,000 to 355,000 ft.
Alternate model structures and parameters were compared using cross-validation.
Isohyetal maps for average annual precipitation (AAP) were prepared from
estimates obtained by kriging and cokriging using the selected models. Isohyets based on
the kriging estimates were very smooth, increasing gradually from the southwest to the
northeast. Isohyets based on the cokriging estimates and the spatial correlation between
AAP and elevation were more irregular and displayed known orographic effects. Indirect
confirmation of the cokriging estimates were obtained by comparing isohyets prepared with
the cokriging estimates to the boundaries of more densely vegetated and/or forested zones.
Estimates for AAP at the repository site were 145 and 165 mm for kriging and cokriging,
respectively. Cokriging reduced estimation variances at the repository site by 55% relative
to kriging. The effectiveness of an existing network of stations for measuring AAP is
evaluated and recommendations are made for optimal locations for additional stations. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37937 |
| Date | 22 May 1990 |
| Creators | Hevesi, Joseph A. |
| Contributors | Istok, Jonathan D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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