The meter emits a series of deafening beeps. Instinctively, everyone covers their ears. Without further ado, course co-leader Matthias Willmann pops the battery out of the device. Exchanging grins, the students continue to carefully lower the cable deeper into the borehole. Today’s task is to measure the quality of the groundwater here in Kappelen, a municipality in the canton of Bern.
It’s only been a few hours since Carole, Gianna, Raffaele and Robyn arrived. The four ETH students are here to complete a three-day module towards a Master’s degree in Environmental Engineering – a course offered by the ETH institute of the same name. Matthias Willmann has been coming to this area of forest for the past 15 years, initially as an ETH employee, recently as an external consultant. All in all, around 20 students are taking part in the module, which aims to map the local groundwater. Willmann has just explained to the group that there are 16 boreholes in the forest. Sunk vertically to over 10 metres, they are permeable below a certain depth. This provides an entry point for groundwater, which can then be analysed by the students.
The group’s first job is to measure the water table and the depth of each borehole. For this purpose, Willmann has brought two water-level meters from the equipment tent, which are similar in appearance to cable reels. In this case, however, the cable is a measuring tape attached not to a plug but rather to a thin metal rod – the measurement probe. He instructs the students to lower this carefully into the borehole. “As soon as the rod hits groundwater, current flows and the small display lamp will light up,” Willmann explains. Some models even feature an acoustic signal.
A feel for fieldwork
It doesn’t take long for the four Master’s students to get the hang of the meter. Initially, they work as a group. Raffaele slowly lowers the cable into the hole, with Carole lending a helping hand. The battery has been reinserted, and as soon as the lamp lights up and the device beeps, Robyn notes the reading on the tape. At borehole 3.1, the water table is at a depth of 3 metres and 95 centimetres. Gianna records the precise measurement. Raffaele then lowers the cable further until he detects slight resistance, which indicates the bottom of the borehole. “You develop a feeling for this,” says Willmann. Once again, Robyn records the reading.
Later, the four students will map the boreholes and plot the level of the water table. This will tell them in which direction the groundwater is flowing. Just like a river above ground, groundwater flows downhill. “The module gives students a feel for the reality of working in the field,” says Willmann. “The insights they get out here are really useful.” Joaquin Jimenez-Martinez, who co-leads the course with Willmann, nods in agreement.
Jimenez-Martinez works as a group leader at ETH Zurich and the Swiss Federal Institute of Aquatic Science and Technology (Eawag). He recently teamed up with ETH’s administrative department for Educational Development and Technology to take a closer look at the role of fieldwork. “The whole teaching process feels different when you have that connection to nature,” he explains. “As teachers, we give a quick introduction but then step back and let the students get on with it – taking measurements, trying stuff out, learning in the field.” He would love to explain the benefits in more detail, he says, but now he must dash for his train back to Zurich.
Meanwhile, the group is busy using a probe to measure groundwater temperature and conductivity. At a depth of 10 to 12 metres, the water has a temperature of 11 degrees Celsius – exactly as expected. The vertical hydraulic conductivity of the groundwater reveals certain details about its composition. Here in Kappelen, everything is as it should be. But an abnormal reading can also indicate the presence of contaminants. This would be a disaster for a country like Switzerland, where 80 percent of potable water is drawn from groundwater.