Messenger - Vol. 4, No. 3, Page T-5 1995 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 study." 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 estuary." 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 wrong." 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 Analysis.