Department of Geoscience

Workpackage 1

WP1. Hydrological-geophysical mapping and method development.
WP leader: Director, PhD Andrea Viezolli (AAG)

WP1 is all about geophysical and hydrological data collection as well as geophysical instrumental developments. The geophysical data are a crucial part of most largescale hydrological/geological modeling problems, and this is also the case in this project. WP1 will give basic data input for WP2, WP3, WP4, and WP5.

The geophysical data to be collected are grouped in three main categories:
1) Mapping with Airborne electromagnetic using the SkyTEM system developed at Aarhus University and SkyTEM ApS (Sørensen and Auken, 2004).
2) Magnetic Resonance Soundings (MRS) will be used for detailed evaluation of aquifer properties and aquifer tests.
3) Geophysical borehole logging will provide a direct link between SkyTEM, MRS, and geological borehole data.

All of the above mentioned data collection will be performed in the Kasted area which lies in close proximity to Aarhus. 

The instrument developments are mainly adressed at the MRS and SkyTEM methods and have have two aims:

1) Development of noise-reduction techniques using a predictive approach. Noise reduction
will enhance the signal-to-noise ratio and enable weight reduction of the AEM system
and/or larger depth of penetration. As a result, AEM would become even more
competitive on the global market.
2) Development of new techniques for providing early times in TEM. Early times are crucial
for mapping the near-surface geology and enables better assessment of flow patterns
and the natural protection provided by geological layers above aquifers. 

A major limitation of the MRS method is the sensitivity to natural background noise,
making the time to take a measurement untenable. To overcome this limitation a set of noise
sensors deployed in a wireless network around the measurement site have been developed, thus
making it possible to reduce or remove the noise level, reduce the measurement time, and/or
increase the depth of investigation. Current state-of-the-art equipment has a limited number
of sensors without much flexibility. This work is linked to the SkyTEM surveys because the development of the noise sensors are from the SkyTEM receiver instrumentation.

The hydrogeological data include drilling logs, spatio-temporally resolved piezometric
head measurements, aquifer pump tests, seepage flux measurements and soil water content
measurements.