Kriging of Hydraulic Conductivity for Subsurface Drainage Design

Abstract

Hydraulic conductivity is an important parameter in the design of subsurface drainage systems. Hydraulic conductivity from field investigations in alluvial soils shows a high spatial variability. The objective of this study was to show how kriging, a linear unbiased estimator, can improve the representation of hydraulic conductivity for subsurface drainage design. The spatial autocorrelation structure used in the kriging estimations was represented by the semivariogram of 3,488 hydraulic conductivity measurements done on a 35,000 ha area in the Nile Delta of Egypt. Results showed that variations of the hydraulic conductivity were isotropic, with a high nugget effect, and a range of influence of 5.6 km. Kriging allowed clear identification as contour maps that could be used to determine blocks of homogeneous hydraulic conductivity. For the 25 drawing areas studied in this paper, differences in design hydraulic conductivities calculated from the kriged and measured values ranged from 114.0% to