Melt water from glaciers makes a significant contribution to the overall discharge of Swiss rivers, especially during hot and dry summers. Consequently, the reduction of the ice volume in the Alps due to the ongoing melting of glaciers will have a strong impact on many fields including the electricity production from hydropower. For predicting the future discharge of rivers, a good knowledge of today’s ice volumes and the topography of the underlying bedrock is crucial. For obtaining this information, we have developed a helicopter-borne ground penetrating radar (GPR) system and a data processing software suite.

The GPR-system is a novel dual-polarization instrument. It consists of two pairs of commercially available radar antennas, which are mounted orthogonal to each other on a wooden platform and carried by a helicopter as an underslung load. Additionally, the system includes 3 GNSS antennas, for accurate positioning and determining pitch, yaw and roll, as well as a laser altimeter for precisely measuring the distance of the antennas to the ground. In parallel to the GPR-system, a data processing software package has been established, which addresses the specific challenges of the recorded data, such as the interference of the radar waves with the helicopter.

Since 2016, the instrument has been used routinely to acquire a large amount of data in various regions of the Swiss Alps and further campaigns are currently taking place. The ultimate goal is to obtain the total volume of ice in the Swiss Alps, in order to provide a complete inventory of the Swiss glaciers. This is done by measuring GPR profiles on a relatively sparse grid, which are then used in combination with glaciological modeling procedures to calculate continuous ice thickness maps and the overall ice volume of individual glaciers.

Figure 1: (a) Helicopter-borne GPR system developed at ETH. (b) Example GPR-profile measured on Glacier de la Plaine Morte. (c) Continuous ice thickness map of Glacier de la Plaine Morte obtained from GPR-data (GPR-profile locations shown by green lines) combined with glaciological modeling.

The team involved in this project include Melchior Grab, Andreas Bauder, Hansruedi Maurer, Lisbeth Langhammer, and Johan Robertsson, ESC member and head of the exploration and environmental geophysics (EEG) group. Detailed information on research activities, teaching, and people of the EEG group can be found in the corresponding sections on the group’s website.

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