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Title: GIS-BASED MODELING OF NONPOINT SOURCE POLLUTANTS IN THE VADOSE ZONE

Author
item Corwin, Dennis
item LOAGUE, KEITH - STANFORD UNIV, CA 94305
item ELLSWORTH, TIMOTHY - UNIV. OF ILLINOIS, IL

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Nonpoint source (NPS) pollution such as salinity, trace elements, pesticides and fertilizers are characteristically spread over large areas at low concentrations. A significant characteristic of nonpoint source pollution problems is the lack of regard for political boundaries and physical barriers between cities, states, nations and continents. The widespread nature of such environmental problems often results in an analogous diffuse acceptance of responsibility for resolution. An ability to accurately assess the present and future impact of human activities on large-scale and even global ecosystem would provide a powerful basis for environmental stewardship and help guide future human actions. The purpose of this feature article is to address the problems and issues involved in modeling NPS pollutants within a spatial and temporal context. The components and considerations necessary to develop GIS-based NPS models of the vadose zone are explained in layman terms. Even though the current trend of combining GIS with one-dimensional models of solute transport in the vadose zone offers great potential for simulating NPS pollutants, a cautionary note is presented to warn overzealous modelers that GIS should never disguise the legitimacy of simulated results nor should these results ever supplant field observations.

Technical Abstract: The information age of the 1990's is a time of global consciousness where scientific and technological advances are assumed capable of solving global environmental problems. A significant characteristic of many environmental problems is the lack of regard for political boundaries and physical barriers between cities, states, nations and continents. The widespread nature of such environmental problems often results in an analogous diffuse acceptance of responsibility for resolution. Thus, an ability to accurately assess the present and future impact of human activities on the global ecosystem would provide a most powerful basis for environmental stewardship and guiding future human actions. To responsibly respond to impaired ecosystem functioning (i.e., with respect to such issues as climatic change, stratosheric ozone depletion, species diversification, erosion, deforestation, desertification, agricultural sustainability, and non-point source pollution), it is necessary to examine these issues not only from a multidisciplinary, systems-based approach, but also with an approach that accounts for spatial and temporal context. The problems and philosophical issues of addressing nonpoint source pollution in the vadose zone within a spatial and tmeporal context is presented.