Validating Water Surface Elevation for a Citizen Science Project in New Hampshire

By Merritt E. Harlan

How and why lake volumes change over time remains a largely unknown question globally. Factors such as precipitation, water table height, evaporation, and human impacts such as lake level drawdown can impact lake volumes over time, potentially resulting in changes in water supply and lentic ecosystems. To learn more about changes in lake volumes at a global scale, the project “Lake Observations by Citizen Scientists and Satellites” (LOCSS) pairs satellite imagery, which can detect lake area over time, with simple lake gauges that everyday citizens can read and collect data from. With the changes in height read from the lake gauge paired with the changes in lake surface area, we can better assess changes in lake volume over time.

Our team alongside a citizen scientist volunteer. Left to right: Dave Olean, Carly Bell, Faye Kuszewski, and Merritt Harlan.

This past week after classes ended in May 2021, we (myself; a University of Massachusetts Amherst Civil and Environmental Engineering graduate student, and two undergraduate students from the University of Massachusetts Amherst Integrating Geosciences and Engineering the Arctic course) traveled to 13 different lakes throughout New Hampshire to install these lake gauges. At each site, we installed a gauge alongside a sign to text in the lake level close to citizen scientist’s homes or public access areas. Although we hope these signs will stay in place for some time, factors such as ice and snow mean that these gauges will shift over time. Thus, precise measurements of the current water surface elevation as it relates to the gauge level at which we installed are needed, tying in a crucial aspect of this work: high-end technology from the UMass Trimble lab.

The Trimble R10 unit acting as a base station to measure the water surface elevation nearby a gauge.

At each location, we surveyed the water surface elevation with the Trimble®R10 GNSS system, allowing us to measure the water elevation up to 2 cm precision. This precision allows us to tie the level at which we install the gauge to a specific water elevation, and so if we ever need to revisit these sites in the spring after snow melt, we will be able to link measurements from citizen scientists across different gauge installations, by remeasuring the water surface elevation at later installs and correcting for the difference. This precision enables continuity of this project across several years of data gathering, enabling further research into the effectiveness of citizen science paired with satellite imagery for monitoring lake changes across the globe. To learn more about this project, and visit sites nearby in Massachusetts and New Hampshire, please check out this website:, and a special thank you to the New Hampshire Volunteer Lake Assessment Program for connecting us with dedicated citizen scientists.

An example of a gauge in Long Pond, New Hampshire.

Trimble Tech Used:

  • Trimble R10

People Involved:

  • Carly Bell, Civil and Environmental Engineering
  • Faye Kuszewski, Civil and Environmental Engineering
  • Merritt Harlan, Civil and Environmental Engineering

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