Determining the hydraulic conductivity spatial structure at the Twin Lake site by grain-size distribution

Concentrations of a radiotracer were measured continuously in observation wells in a field test conducted in the sandy aquifer at the Chalk River site. These measurements were used recently (Dagan et al. 1997) to assess the values of the parameters characterizing the spatial distribution of logconductivity (mean, variance, and horizontal and vertical integral scales). Soil samples were taken independently from a few wells and the grain-size distributions were determined by sieve analysis. The aim of the present study is to infer the aforementioned parameters' values of logconductivity with the aid of grain-size distributions. A Carman-Kozeny-type formula was used to derive the sample hydraulic conductivity and a geostatistical analysis to infer the parameters characterizing the logconductivity spatial distribution. The agreement for the results based on the two methods was quite satisfactory in view of the various approximations adopted by the two methodologies.