Geostatistical methods were used to find efficient and accurate means for
salinity assessment using regionalized random variables and limited sampling. The
random variables selected, sodium absorption ratio (SAR), electrical conductivity
(EC), and clay content were measured on samples taken over an area of fifteen
square miles. Ordinary kriging and co-kriging were used as linear estimators. They
were compared on the basis of average kriging variance and sum of squares for error
between observed and estimated values.
The results indicate a significant improvement in the average kriging variance
and sum of squares by using co-kriging estimators. EC was used to estimate SAR
because of the high correlation between them. This was not true for clay content.
A saving of two-thirds of the cost and time was achieved by using electrical
conductivity as an auxiliary variable to estimate sodium absorption ratio. The
nonlinear estimator, disjunctive kriging, was an improvement over co-kriging in terms
of the variances. More information at the estimation site is a more important
consideration than when the estimator is linear. Disjunctive kriging was used to
produce an estimate of the conditional probability that the value at an unsampled
location is greater than an arbitrary cutoff level. This feature of disjunctive kriging
aids salinity assessment and reclamation management.
A solute transport model was used to show how saptially variable initial
conditions influenced the amount of water required to reclaim a saline soil at each
sampling point in a simulated leaching of the area. / Graduation date: 1992
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36881 |
| Date | 17 December 1991 |
| Creators | Al-Taher, Mohamad A. |
| Contributors | Warkentin, Benno P. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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