Water beneath the Alps
The geophysicist Landon Halloran uses a portable gravimeter to measure gravity, which increases slightly when there is more water in the ground. | Photo: Dominik Amschwand
When there’s very little snow during winter, that’s when alpine groundwater becomes especially important in feeding the rivers that provide the water supply for millions of people. “But there’s a big question mark over what actually happens underground”, says Landon Halloran, a geophysicist at the University of Neuchâtel. It’s very complex and costly to measure groundwater directly in the mountains by drilling boreholes.
Halloran has now developed an easier, more precise method to take these measurements. He uses a portable gravimeter to measure gravity, which increases slightly when there is more water in the ground. This method enables him to detect changes in groundwater levels down to less than ten centimetres – which is more than precise enough to assess changes both across the seasons and from year to year.
