Once lost
in the mists of time, the colonial hydrology of the northeastern United States has
been reconstructed by a team of geoscientists, biological scientists and social
scientists.
The
results, which extend as far back as the year 1600, appear in the current issue
of the journalEnvironmental Science & Technology (ES&T) .
The
findings provide a new way of uncovering the hydrology of the past, and will
lead to a better understanding of hydrologic systems now and in the future, the
scientists say.
"We
outline a methodology for synthesizing modern scientific data with historical
records, including anecdotal sources," says Christopher Pastore of the University of New Hampshire, the paper's lead author.
"It underscores the role of humans in an assessment of hydrologic
change."
Throughout
American history, water resources have played an integral role in shaping
patterns of human settlement and networks of biological and economic exchange.
"The
research emphasizes the effect of human activities on the evolution of watersheds
and on the dynamics of ecosystems important to water sustainability," says
Thomas Torgersen, program director in the National Science Foundation’s (NSF)
Division of Earth Sciences, which funded the research.
The
scientists divided their study area into three geographic and socio-political
subregions: New England; the Middle Colonies; and the Chesapeake.
They then
looked at the ways in which physical variables – such as soil, vegetation and
climate – combined with socio-political factors to influence each subregion's
hydrologic environment.
In New England, for example, close-knit religious
communities with strong central governments concentrated their economic efforts
on fur-trading and timber extraction, according to the paper's co-authors,
which include Charles Vorosmarty of the City University of New York, principal
investigator on the NSF grant.
The Chesapeake region, on the
other hand, was settled largely by young, unskilled men who cleared trees and
planted tobacco fencerow to fencerow. "This caused extensive erosion,
which dramatically altered rivers," says Pastore.
The Middle
Colonies were characterized by diverse social, cultural and religious
traditions, and feudal-style estate agriculture.
Integration
of human decision-making into analyses of land-cover change, engineering and
climate change is fundamental to understanding subregional hydrologic patterns
and how they interact, the scientists say.
They
recommend two metrics for quantifying hydrologic change.
The first,
which they call a simple water balance, takes into account precipitation,
evapotranspiration and water storage, which can be used to track changes in
annual river discharge.
The second,
termed mean water residence time, or the average time a water molecule spends
in one place, also can be used to calculate the amount of water moving through
a system.
The
resulting information helps determine past water residence times, which, in
turn, allow scientists to infer changes in the biogeochemistry of rivers and
streams.
Many
pathogens, or disease-causing organisms, are linked to water flows. An
understanding of historical water residence times, says Pastore, may lead to
new insights into how diseases are transmitted today.
Other
co-authors of the paper are: Mark Green of Plymouth State University; Daniel
Bain of the University of Pittsburgh; Andrea Munoz-Hernandez of the City
University of New York; Jennifer Arrigo of East Carolina University; Sara
Brandt of the U.S. Geological Survey in Northborough, Mass.; Jonathan Duncan of
the University of North Carolina at Chapel Hill; Francesca Greco of King's
College, London; Hyojin Kim of the University of California at Berkeley; Sanjiv
Kumar of Purdue University; Michael Lally of the University of Massachusetts at
Amherst; Anthony Parolari of MIT; Brian Pellerin of the U.S. Geological Survey
in Sacramento, Calif.; Nira Salant of Utah State University; Adam Schlosser of
MIT; and Kate Zalzal of the University of Colorado at Boulder.