38 research outputs found
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Statistical analysis of hydrological data from five small watersheds in western Oregon : Volume 1 : Analysis
Published June 1985. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
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Statistical analysis of hydrological data from five small watersheds in western Oregon : Volume II: Data
Published June 1985. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
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Statistical analysis of climatological data to characterize erosion potential : 1. precipitation events in western Oregon
Periods of precipitation with certain combinations of characteristics
(e.g„ high intensity rainfall on saturated soil) can lead to appreciable
soil loss in western Oregon. In order to assign realistic probabilities to
the occurrence of these periods for use in predicting long-term erosion rates,
a soil erosion-specific definition of a precipitation event is applied to more
than 31 years of hourly wet season precipitation data from Portland, Salem,
and Eugene, Oregon. The values of nine characteristics (duration, magnitude,
average intensity, maximum intensity, hours between events, and four measures
of antecedent rainfall) that are associated with each event are examined.
The statistical analysis of the precipitation event characteristics
includes consideration of the marginal distributions and order and return
statistics of the individual characteristics as well as joint and conditional
distributions of several pairs of characteristics. The order and return statistics
provide information about extreme values of individual characteristics,
whereas the probabilities of occurrence of some combinations of characteristics
are estimated by the joint distributions. Examination of the conditional
distributions suggests the types of relationships that exist among the
characteristics. The results of these analyses provide general information
regarding the types of precipitation events that occur in western Oregon as
well as estimates of specific probabilities that are important in the modeling
and forecasting of soil erosion in this region.Published October 1984. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
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Multivariate geostatistical analysis of groundwater contamination by pesticide and nitrate
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Influence of deterministic geologic trends on spatial variability of hydrologic properties in volcanic tuff
Hydrologic properties have been measured on outcrop samples taken from a detailed, two-dimension grid covering a 1.4 km outcrop exposure of the 10-m thick non-welded-to-welded, shardy base microstratigraphic unit of the Tiva Canyon Member of the Miocene Paintbrush Tuff at Yucca Mountain, Nevada. These data allow quantification of spatial trends in rock matrix properties that exist in this important hydrologic unit. Geologic investigation, combined with statistical and geostatistical analyses of the numerical data, indicates that spatial variability of matrix properties is related to deterministic geologic processes that operated throughout the region. Linear vertical trends in hydrologic properties are strongly developed in the shardy base microstratigraphic unit, and they are more accurately modeled using the concept of a thickness-normalized stratigraphic elevation within the unit, rather than absolute elevation. Hydrologic properties appear to be correlated over distances of 0.25 to 0.3 of the unit thickness after removing the deterministic vertical trend. The use of stratigraphic elevation allows scaling of identified trends by unit thickness which may be of particular importance in a basal, topography-blanketing unit such as this one. Horizontal changes in hydrologic properties do not appear to form obvious trends within the limited lateral geographic extent of the ash-flow environment that was examined. Matrix properties appear to be correlated horizontally over distances between 100 and 400 m. The existence and quantitative description of these trends and patterns of vertical spatial continuity should increase confidence in models of hydrologic properties and groundwater flow in this area that may be constructed to support the design of a potential high-level nuclear waste repository at Yucca Mountain
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Statistical analysis of climatological data to characterize erosion potential : 4. freezing events in eastern Oregon/Washington
The occurrence of frozen soil has a major effect on runoff and soil loss
in the Pacific Northwest. Hence, information regarding the probabilities of
occurrence of periods during which the soil may be frozen is necessary in order
to adequately forecast long-term erosion rates for this region. In order to
assign realistic probabilities to the occurrence of these periods, a long record
of hourly surface air temperature data from Pendleton in eastern Oregon
and Walla Walla in eastern Washington are summarized in terms of freezing
events. The values of several characteristics of freezing events which may be
useful for predicting soil frost occurrence are examined.
The statistical analysis of the freezing event characteristics includes
consideration of the marginal distributions and order and return statistics of
the individual characteristics as well as joint and conditional distributions
of several pairs of characteristics. The order and return statistics provide
information about extreme values of individual characteristics, whereas the
probabilities of occurrence of some combinations of characteristics are estimated
by the joint distributions. Examination of the conditional distributions
suggests the types of relationships that exist among the characteristics. The
results of these analyses provide general information regarding the types of
freezing events that occur in eastern Oregon and eastern Washington as well as
estimates of specific probabilities that are important in the modeling and
forecasting of soil erosion in this region.Published October 1984. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
Recommended from our members
Statistical analysis of climatological data to characterize erosion potential: 5. joint precipitation and freezing events in Western Oregon
When precipitation falls on frozen soil, serious soil loss can
occur. In order to assign realistic probabilities to the occurrence of
this condition for use in predicting erosion rates over long time
periods, a technique for combining characteristics of precipitation and
air temperature records is applied to more than 31 years of hourly, wet
season data from Portland, Salem, and Eugene, Oregon. Periods of
overlapping precipitation and freezing air temperature events are
combined into clusters and the values of thirteen characteristics that
are associated with each cluster are examined.
The statistical analysis of the cluster characteristics includes
discussions of the marginal distributions and order statistics of the
individual characteristics as well as joint distributions of several
pairs of characteristics. The order statistics provide information
about extreme values of individual characteristics (e.g., minimum temperature)
whereas the probabilities of occurrence of certain combinations
of characteristics (e.g., precipitation amount and freeze index) are
estimated by the joint distributions. The results of these analyses
provide information regarding the types of precipitation events that
occur in combination with freezing air temperatures in western Oregon as
well as estimates of specific probabilities that are important in the
modeling and forecasting of soil erosion in this region.Published March 1984. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
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Subsurface drainage : an erosion control practice for western Oregon?
Published February 1985. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
Recommended from our members
Statistical analysis of climatological data to characterize erosion potential : 6. joint precipitation and freezing events in eastern Oregon/Washington
When precipitation falls on frozen soil, serious soil loss can
occur. In order to assign realistic probabilities to the occurrence of
this condition for use in predicting erosion rates over long time
periods, a technique for combining characteristics of precipitation and
air temperature records is applied to hourly wet season data from
Pendleton, Oregon and Walla Walla, Washington. Periods of overlapping
precipitation and freezing air temperature events are combined into
clusters and the values of thirteen characteristics that are associated
with each cluster are examined.
The statistical analyses of the cluster characteristics include
discussions of the marginal distributions and order statistics of the
individual characteristics as well as joint distributions of several
pairs of characteristics. The order statistics provide information
about extreme values of individual characteristics (e.g., minimum temperature)
whereas the probabilities of occurrence of certain combinations
of characteristics (e.g., precipitation amount and freeze index) are
estimated by the joint distributions. The results of these analyses
provide information regarding the types of precipitation events that
occur in combination with freezing air temperatures in eastern Oregon
and Washington as well as estimates of specific probabilities that are
important in the modeling and forecasting of soil erosion in this
region.Published April 1984. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
Recommended from our members
Statistical analysis of climatological data to characterize erosion potential : 3. freezing events in western Oregon
The occurrence of frozen soil has a major effect on runoff and soil loss in western Oregon. Hence, information regarding the probabilities of occurrence of periods during which the soil may be frozen is necessary in order to adequately forecast long-term erosion rates for this region. In order to assign realistic probabilities to the occurrence of these periods, 31 years of hourly temperature data from three locations in western Oregon (Portland, Salem, and Eugene) are summarized in terms of freezing events. The values of several characteristics of freezing events which may be useful for predicting soil frost occurrence are examined. The statistical analysis of the freezing event characteristics includes consideration of the marginal distributions and order and return statistics of the individual characteristics as well as joint and conditional distributions of several pairs of characteristics. The order and return statistics provide information about extreme values of individual characteristics, whereas the probabilities of occurrence of some combinations of characteristics are estimated by the joint distributions. Examination of the conditional distributions suggests the types of relationships that exist among the characteristics. The results of these analyses provide general information regarding the types of freezing events that occur in western Oregon as well as estimates of specific probabilities that are important in the modeling and forecasting of soil erosion in this region.Published October 1984. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo