COMPARISON OF SATURATED HYDRAULIC CONDUCTIVITY MEASUREMENT METHODS FOR A GLACIAL-TILL SOIL

Hydraulic conductivity is the single most important hydraulic paramete r for flow and transport-related phenomena in soil, but the results fr om different measuring methods vary under different field conditions. To evaluate the performance of four in situ saturated hydraulic conduc tivity (K(s)) measuring methods, K(s) measurements were made at four d epths (15, 30, 60, and 90 cm) and five locations on a glacial-till.soi l of Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll)-Clarion (fine -loamy, mixed, mesic Typic Hapludoll) association. The four in situ me thods were: (i) Guelph permeameter, (ii) velocity permeameter, (iii) d isk permeameter, and (iv) double-tube method. The K(s) was also determ ined in the laboratory on undisturbed soil cores collected from all th e five sites and four depths. The Guelph permeameter method gave the l owest K(s) values, possibly because of small sample size, whereas the disk permeameter and double-tube methods gave maximum values for K(s) with minimum variability, possibly because of large sample size. Maxim um variability in K(s) values for soil cores at shallow depths may hav e occurred because of the presence or absence of open-ended macropores . Estimates of K(s), however, are most comparable for the velocity per meameter and the laboratory method using a constant-head permeameter.