MAKING BASIC MEASUREMENTS AT THE INTERFACE

Hands-on training can help a person make useful measurements at this interface. In learning many skills, and this is one of them, physical practice can be crucial, especially if you hope to trouble shoot and make sense of results.

Basic methods for collecting data at this interface have been taught at the University of Waterloo since 1977. Participants collected pore-water samples and measured hydraulic parameters in a setting conducive for learning. The module began with a 2-hr evening lecture covering salient features of the interface, an overview of available methods and an introduction to using seepage meters, mini-piezometers and small-stream gauging techniques. The next day, participants donned hip waders and conducted 4-hours of fieldwork. They each installed piezometer screens, which they made the evening before. They emplaced seepage meters, vent tubes and plastic collection bags. They measured hydraulic conductivity using Hvorslev's constant head method and the Darcy equation. Measurements were made in triplicate. Mistakes were not uncommon, but were valued. Learning came through doing, taking risks and questioning. Participants completed a written assignment and answered questions specific to their data and to both generic and practical situations. The exercise was almost always rewarding, sometimes more so when temperatures were not ideal.

In this presentation I will provide tips on teaching in the field along with measurement pitfalls, and I will ask whether special applications of seepage meters and mini-piezometers avoid the pitfalls or reduce the need for physical experience.