Temperature sounding method

Basis

Fluid movements in the subsurface often lead to temperature anomalies, since the fluid often shows a different initial temperature than the undisturbed soil. Due to the advective heat transport associated with the fluid movement, the ground temperature equilibrates with the fluid temperature in and around the areas with fluid flow. The soil temperature can therefore be used as a reliable tracer to detect and locate fluid movements in the subsurface.

Method

With the temperature sounding method developed by GTC Kappelmeyer® in 1989, temperature measurements in sediments and embankments can be carried out down to a depth of approx. 40 m. Boreholes have to be drilled for greater investigation depths.

A hollow rod with a small diameter is driven into the ground and equipped with a temperature sensor chain. After a short thermal equilibration phase, the ground temperatures at different depths are simultaneously measured with a portable high-precision measuring device. Temperature anomalies can already be determined on site by mapping the measured data. Thus, both horizontal and vertical boundaries of fluid movements can be localised.

Since the development of bend-optimised optical fibres, fibre-optic sensing cables can additionally be combined with the temperature sounding method (retrofit method).

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