MODELING SPATIAL VARIABILITY OF SATURATED HYDRAULIC CONDUCTIVITY USING FOURIER-SERIES ANALYSIS

A study was conducted to develop a computer model to simulate the spat ial variability of field-measured saturated hydraulic conductivity (K( s)) using Fourier series analysis. K(s) measurements, both in situ and in the laboratory, were made at 150 and 300 mm depths at regular inte rvals of 4.6 m on two perpendicular transects crossing each other at t he centre of a no-till field. Three Fourier series models, with a fini te number of harmonics, were developed to simulate the variability in K(s) values. These models included the regular Fourier series model, t he half-range Fourier series model with only cosine terms, and the hal f-range Fourier series model with only sine terms. Also, a test of sig nificance was conducted with the first five and eight terms of the Fou rier series models. This test indicated that with only five or eight t erms model performances were not significantly different from each oth er at the 0.05 level. The overall results of this study indicated that spatial variability in the K measurements made with both techniques, field and laboratory, can be represented successfully with half-range Fourier series with only cosine terms. Statistical analysis of predict ed and observed K(s) values indicated that the two sets were not signi ficantly different from each other at the 0.05 level.