Lakes are fascinating ecosystems, and provide valuable resources for drinking water, aquaculture, and recreation. But they are also extremely sensitive to climate and land-use changes.
Lake Geneva (or Lac Léman) sits along the France-Switzerland border and is home to LéXPLORE, a unique floating laboratory used to assess the impact of global changes and monitor lake health.
Challenge: Filling the Wave Data Gap
LéXPLORE is a 10m by 10m pontoon equipped with a range of high-tech sensors and vertical profilers to provide continuous, 24/7 data on Lake Geneva’s conditions. Data is used to compile a core dataset–available publicly via the Datalakes online portal–and to support specific research projects.
However, despite the wealth of technologies deployed from the LéXPLORE platform, a wave buoy was missing.
Guillaume Cunillera, Chief Technical Officer of the LéXPLORE platform, explains that his predecessor, Sébastien Lavanchy, and Damien Bouffard, professor of aquatic physics and modeling, wanted to add a wave buoy to the platform for quite some time. After exploring the options available, a NexSens CB-450 was installed.
Solution: Deploying a NexSens CB-450
The CB-450 buoy, equipped with a SeaView Systems SVS-603HR and NexSens X-Series data logger, was installed on the platform’s protection perimeter.
Cunillera explains, “On our protection perimeter, the yellow buoys are directly anchored at the bottom of the lake. In between, we have secondary buoys that are linked together with chains. And the wave buoy is attached in between two secondary buoys.”
Currently, the buoy’s SVS-603 takes hourly measurements. Over approximately 19 minutes, the sensor records over 2,000 data points, which are averaged and sent to the host modem on the platform. Data is translated from binary to ASCII and sent to Datalakes–the online portal where all LéXPLORE data is publicly accessible. The next hour, it starts again.
Thanks to the buoy system, wave data (including the highest 10%), period and direction are now available to researchers and the public.
Benefit: Enabling greater insight into wave conditions at Lake Geneva
“The NexSens system fits perfectly in our core data sets,” Cunillera highlights, “And several researchers need those data.”
The platform’s technical team uses buoy data “to follow and have a better understanding of the [impacts of] strong wind and storm events on the infrastructure.”
Scientists working on the Wind2Waves project–which studies the evolution of the directional wave energy spectrum–use data from the buoy as well as that collected from their own system and sensors.
Several other projects use the data, with research questions ranging from how to assess primary production in the lake through optical in-situ measurements and satellite observations, to investigating the relationship between temperature in the first few micrometers and centimeters of water depth, and understanding the carbon cycle and gas exchange at the air-water interface.
In the future, Cunillera wants to increase the sampling frequency of measurements to get a better view of incoming waves.
“We would ideally like to adjust the resolution of the measures based on several factors, such as wind values from our weather station, voltage of the battery, or special events,” he states.
Bottom Line
With a long history of environmental monitoring, the LéXPLORE platform represents a cutting-edge advancement in data collection on Western Europe’s largest lake. In response to climate change and anthropogenic pressures, it’s enabling scientists to measure and better understand how the lake and its surrounding ecosystem are evolving.
Equipment
The X3 is an all-in-one environmental data logger designed for both pole/wall mount and buoy-based applications. Compatible sensors include water quality instruments, temperature strings, ADCP’s, water level sensors, and weather stations.
The NexSens CB-450 Data Buoy is designed for deployment in lakes, rivers, coastal waters, harbors, estuaries and other freshwater or marine environments.
