Thermal measurement of soils using a multineedle probe with a pulsed‐point source

Abstract

The shallow temperature survey has long been recognized as a promising method for rapid reconnaissance exploration for shallow aquifers (Cartwright, 1968). The problem with the method has been the need for additional thermal property measurements to interpret the temperature anomalies correctly. The controlling property for this work is the thermal diffusivity [Formula: see text], defined as the ratio of conductivity [Formula: see text] to heat capacity [Formula: see text]. I have developed a multineedle thermal probe that can be used to make rapid, direct measurements of the thermal diffusivity of soil, as well as its conductivity. This is an improvement over previous methods which either required a long monitoring time (Birman, 1969) or which computed diffusivity indirectly from single‐needle measurements of conductivity (LeSchack et al., 1979).