Caroline Templeton '14 Devised System for Plotting Lake's Topography

December 21, 2012
bathymetric map with zones of yellow, green, and blue

This bathymetric map indicates that Lake Waban consists of two sub-basins that follow the direction of two underlying pre-glacial valleys. Its deepest depth is probably 12.2 meters, or 40 feet.

How did we find that out? As part of a GEOS-350 independent research project with Assistant Professor of Geosciences Katrin Monecke, geosciences and computer science major Caroline Templeton ’14 set up a depth survey system to assess the topography of a body of water. The system, which can be run easily from any boat, uses a simple echo-sounder, a global positioning system (GPS) device and a computer connection to collect depth data every second.

Using this system, Monecke's GEOS-304 Sedimentology class surveyed Lake Waban along a dense grid of lines, collecting more than 12,000 depth readings. The collected data was sorted using a program code written by Templeton and then processed with geographic information systems (GIS) software.

Bathymetric maps use color to indicate water depth and illustrate topography beneath the surface. According to the National Oceanographic and Atmospheric Administration, most bathymetric images use colors on the “warm” end of the spectrum–red, orange, and yellow–to represent shallower water. As the water deepens, the colors shift through green, blue, and finally into violet. Dry land is usually shown in white. Areas that are the same distance below the surface will be shown in the same color, and the relationship between color and depth illustrates shapes and structures on the bottom of the body of water.

"I really enjoyed working on this project," said Templeton, "because it involved a lot of problem solving. The project required a lot of ingenuity because there was no pre-existing procedure that I could refer to when I encountered roadblocks." Templeton, who will spend next semester abroad, will be away from Lake Waban for awhile, but says the the plan is to use the survey system for future lake exploration. "The main purpose for the bathymetry survey is to help determine good locations for sediment cores. We planned to use the cores to look for evidence of historical earthquakes."

Professor Monecke’s work focuses on sedimentation and surficial geology, and she advised Templeton in her research, but notes that—as with so many things at Wellesley—cross-disciplinary efforts helped greatly to make this project happen: Rowing coach Austin Works provided the boat; lifeguard and geosciences major Caroline "Rosie" Duncan ’13 navigated the team safely on the lake; and Carolin Ferweda, instructional technologist for GIS and statistics from Library and Technology Services, and Alden Griffith, assistant professor of environmental studies, helped with the GIS software.