Messenger - Vol. 4, No. 3, Page T-5
On Technology
Eyes in the sky assist UD researchers

     To study population trends, analyze damage to wetlands, predict
the location of ancient Indian burial grounds or track ocean currents,
UD researchers use Geographic Information Systems (GIS) and remote-
sensing technologies.
     Because they combine digitized map information and other data
with images collected by remote-sensing devices on satellites, GIS can
reveal the impacts of pollution, urban development and weather events.
At the University, this technology is used by students and faculty in
the colleges of Agricultural Sciences, Marine Studies and Urban
Affairs and Public Policy, as well as the Department of Geography in
the College of Arts and Science.
     "Our GIS and remote-sensing capabilities are truly extraordinary
for a University," reports Vic Klemas, director of the Remote Sensing
Center and professor of marine studies. "We're especially lucky to
have the remote-sensing technology for gathering environmental data
for entire coastal regions that would otherwise be very difficult to
     Based on this capability, in fact, the University was invited to
participate in several major studies of coastal watersheds, including
a study sponsored by the National Oceanic and Atmospheric
Administration (NOAA) to determine how the development of coastal
watersheds is changing estuarine life and water quality. Specifically,
researchers want to know what happens to wildlife when marshes are
drained or developed, and when coastal regions become polluted. To
ensure that key environmental issues are addressed, this study is
conducted by an interdisciplinary team of physical/biological
oceanographers, remote-sensing specialists and marine policy experts.
     The Delaware Estuary, fed by the Delaware River and tributaries,
is a critical resource for many diverse life forms, including people,
Klemas notes. To monitor the environmental health of the estuary,
University researchers are measuring the productivity of surrounding
wetlands, based on the biomass or dry weight of plants. "Wetlands
serve as a buffer zone between dry land and the estuary," Klemas
explains. "They help filter out sediment, excess nutrients and some
toxins, thereby improving the quality of water that enters an
     Unfortunately, Klemas says, studying the health of wetlands has
traditionally required uprooting plants to measure their biomass-an
indicator of photosynthesis and, therefore, productivity. But, a new
technique developed at the University allows researchers to assess
biomass non-invasively, by measuring reflected light with remote
sensors on satellites. Doctoral student Oliver Weatherbee of Columbia,
S.C., is using this approach to evaluate changes to wetlands areas
over a 10-year period.
     "We're interested in an invasive wetland reed called phragmites,"
Weatherbee says. "The presence of these plants is considered evidence
of an environmental disturbance because it displaces other native
plants. So, if we see a big increase in the number of these plants
over a 10-year period, that would suggest that something is very
     Geographic Information Systems and remote-sensing technologies
also support weather and agricultural research. Based on satellite
images, Xiao-Hai Yan, professor of marine studies, was able to show
that the Western Pacific Warm Pool-an ocean region influenced by El
Nino events and global climate changes-is actually getting warmer and
larger. El Nino is a warm ocean current that flows south along the
western coast of South America and appears to disrupt the climate in
distant places.
     "This increase in temperature and size may be related to solar
irradiance variabilities, El Nino, volcanic activities and global
warming," says Yan, who also is associate director of the remote
sensing center.
     Economist John Mackenzie, an associate professor in the
Department of Food and Resource Economics, uses GIS software to
determine the costs and benefits of various strategies for reducing
nitrate contamination of the water supply. Nitrate-a natural byproduct
of the decomposition of plants, animals and agricultural
fertilizers-may cause health problems, especially in unborn infants.
The U.S. Environmental Protection Agency has, therefore, established a
"one-size-fits-all" limit of 10 parts per million (ppm) for nitrate in
drinking water. Yet, Mackenzie says, different geographic regions may
be best served by different abatement strategies, depending on such
complex factors as land-use patterns and consumer demand for higher
water quality.
     To assess the value of various abatement strategies, Mackenzie
and doctoral student John Sparco of Wilmington, Del., first developed
a model that predicts which groundwater systems are most susceptible
to nitrate contamination in Sussex County. Mackenzie also is working
with research associate Rodolfo Tanjuakio to integrate census and
housing data into a map of toxic waste sites. The resulting
information should illustrate how property values are affected by
proximity to toxic waste sites.
     At the University, remote-sensing information is available from
three different satellites, Klemas says. Land-based studies rely on
data from Landsat (operated by the National Aeronautics and Space
Administration), as well as the French "SPOT" (Satellite pour
l'Observation de la Terre). For ocean studies, new data is available
on a daily basis from an Advanced Very High Resolution Radiometer
sensor aboard a satellite maintained by NOAA.
     Images from these sources are downloaded to the University's
Satellite Receiving Station and are then combined with other types of
information using GIS software programs, such as Earth Resources Data