Environmental Engineering Reference
In-Depth Information
show how the solutions evolved from pollutant removal to land use management
over four decades.
Brandywine Model Project (1972-1974)
The Brandywine River, a 320-square mile watershed draining from the Piedmont
Plateau in southeastern Pennsylvania into Delaware and the Christina River, has
long been the subject of water resources issues, since it serves as the only source
of water supply for the city of Wilmington, Delaware, as well as a number of
smaller upstream communities in Pennsylvania. This small river also served as
a source of power and process water for various industries during the eighteenth
and nineteenth centuries, from paper and steel to gunpowder and chemicals. By
the late nineteenth century the quality of water had deteriorated to critical levels,
but various water experts disagreed on the sources and degree of pollution. In
1914 a liquid chlorine system was installed at the water plant, with a resulting
drop in mortality from typhoid fever: from an average of 36 deaths for each of
the previous 30 years, to zero.
The conflict over water quality continued between the two states through the
twentieth century, with various pollution incidents fueling the political fire, and
suburban growth in the Pennsylvania portion of the watershed spilling over from
the Philadelphia region into former farm fields adding to the various water quality
impacts. In 1972, a newly founded watershed group, the Brandywine Conser-
vancy, initiated an effort to develop a comprehensive model of the river system,
linking water quality to changing land uses within the basin. I was selected as
research director, with an advisory committee comprised of Luna Leopold, U.S.
Geological Survey (USGS), Ruth Patrick, Academy of Natural Sciences, and Fred
Lee of the University of Wisconsin at Madison, and included participation by
Notre Dame University, Penn State University, the USGS, the Stroud Research
Institute, the University of Delaware, and West Chester University.
A network of continuous recording water quality stations had been estab-
lished previously by CA through the Chester County Health Department and
served as the framework for several years of water quality data collection and
research, through 1974. The most important data set was compiled during several
storm runoff periods, when the corresponding measurement of hydrographs and
chemographs were observed. In addition, sampling during base flow periods gave
the first documentation of phosphorus mass transport through the river network. A
geographic information system was also developed, utilizing a raster-format sta-
tistical sampling design, and these land use data were correlated with the resulting
mass transport flux from developed portions of the watershed. Some 14 research
reports were issued in 1974, covering various aspects of land use and water
quality, and the significant difference in mass transport for certain particulate-
associated pollutants, especially phosphorus, between dry and wet weather flows
(Figures B-3 and B-4). A model was also developed relating the dynamics of
oxygen in a river system as a function of benthic conditions and the cycling of
nutrients through the flowing stream.
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