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Statistical Analysis of Salinity and Texture Effects on Spatial Variability of Soil Hydraulic Conductivity
Author(s) -
Bresler Eshel,
Dagan G.,
Wagenet R. J.,
Laufer A.
Publication year - 1984
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1984.03615995004800010004x
Subject(s) - variogram , soil science , spatial variability , soil texture , hydraulic conductivity , salinity , sill , geostatistics , mathematics , statistics , hydrology (agriculture) , environmental science , soil water , geology , geotechnical engineering , kriging , oceanography , geochemistry
A statistical analysis that identifies the dominant factors responsible for the spatial variability of the saturated conductivity ( K s ) in a selected field is presented. The variables are considered random functions of the space coordinates. Two types of stationarity are investigated: constant mean and stationary variogram (stationarity of order 2) and trend of the means (nonstationarity of the mathematical expectation) with stationary covariances. Linear models of statistical dependence were used. Elimination of factors of minor importance was based on correlation analysis. Electrical conductivity (EC) and percent sand were the most important independent variables, whereas K s was the dependent variable. The analysis showed that soil salinity (EC) accounted for only 10 to 15% of the variability of K s texture (percent sand) explained 25 to 45% of the K s variability, and 10 to 15% of the variability was explained by the interaction between salinity and texture. Various soil factors other than salinity and texture accounted for 30 to 50% of the variability in K s . Semivariograms and covariograms of K s , EC, and percent sand did not have a sill because of a significant horizontal linear trend. Calculations showed that the trend accounted for about a half of the variability of the original data. Semivariograms and covariograms of a new population of residuals after extracting the trend gave values of the sills equal to the variances. The integral scale of the residuals of K s and percent sand was estimated to be about 15 to 20 m, whereas salinity (EC) did not display a spatial structure. The results can be generalized for other studies with different values of variances and covariances of soil salinity and soil texture.