Competence Center for Material Moisture (CMM)

New Method for the Integral Determination of Soil Moisture underneath Power Lines

Conventional methods to determine soil moisture yield point data. Due to the small-scale variability of the soil, however, these values cannot be extrapolated to larger areas needed as input parameters for the modeling of climate phenomena in meteorology, for instance.

Linear measurement methods (TAUPE sensors) produce results which may be combined to cover smaller areas up to some ten thousand square meters, but require installation of sensors in the ground and data acquisition equipment.

The patented “free-line sensing” method has the advantage that it can use existing power lines and yields integral soil moisture values in the area of the power lines over distances of up to twenty kilometers. Measurement accuracy is sufficient for meteorological modeling. The data can also be used for the calibration of satellite data, control of large-area irrigation of agricultural areas, or the monitoring of flood-prone areas.

The method uses high-frequency signals applied to the power line. Their electromagnetic propagation behavior is influenced by the dielectric properties of the ground. For studies under a preliminary technology transfer project, EnBW made available a 110 kV line between Durmersheim and Daxlanden.