“How Walden Works: The Quiet Pattern of the Pond": A talk by John M. Nevison

September 10, 2017 - 3:00pm - 4:30pm
Thoreau Farm

As Henry David Thoreau visited and revisited Walden Pond, he often took time to observe the rising and the falling of the Pond's water level. How the Pond's level was tied to the fluctuations of the weather and to the structure of the underlying geology of the Pond remained a mystery.

In 2001, the U.S. Geological Survey published a scientific report entitled "Geohydrology and Limnology of Walden Pond, Concord, Massachusetts" by John A. Colman and Paul J. Friesz. The report made it possible to answer many of Thoreau's questions about the Pond's fluctuating levels.

This talk will begin with a simple physical model of Walden Pond, develop an annual systems dynamic model of the Pond, take a side trip to view a statistical model (a multiple linear regression) to predict this years Pond level, and conclude with a seasonal month to month dynamic model. Validating tests will lead to some final surprising answers to Thoreau's questions. It will reveal the "ideal" Pond's seasonal pattern for the first time.

This event is free and open to the public. Email margaretcb@thoreaufarm.org to make a reservation. Sponsored by Thoreau Farm and the Thoreau Society.

John M. (Jack) Nevison is President of New Leaf Project Management and lives within a half-mile of Walden Pond. He is the author of six books and numerous articles on computing and management. His first simulation model, about a watershed ecosystem, was published in 1974. His most recent white paper explains the ideal seasonal fluctuation in the water level of Walden Pond.