Submitted to: Encyclopedia of Water
Publication Type: Book / Chapter
Publication Acceptance Date: 10/25/2004
Publication Date: 12/1/2005
Citation: Corwin, D.L., Loague, K. 2005. Modeling non-point source pollutants in the vadose zone using GIS. J.H. Lehr (ed.) In: Encyclopedia of Water (Volume 5). John Wiley and Sons, Inc. New York, NY. pp: 299-305 Interpretive Summary: Non-point source (NPS) pollutants such as fertilizers, pesticides, salinity, and trace elements, to mention a few, are characteristically spread over wide areas of the landscape and often cause long-term chronic health effects. These characteristics have made NPS pollutants a global concern . To better manage the detrimental environmental and health impacts of NPS pollutants it is crucial that they can be modeled to better synthesizing current knowledge into a useable form for policy decisions. This article is part of the Encyclopedia of Water and is intended to provide the general scientific audience with a basic understanding of sources, significance, and global impact of NPS pollutants; justification for modeling NPS pollutants and the complexities involved; the basic components of a NPS pollutant model; and the future direction of modeling NPS pollutants.
Technical Abstract: Non-point source (NPS) pollutants are characteristically diffuse in nature, tend to have a long active presence in the global ecosystem, and result in chronic health effects on humankind. Due to their nature, NPS pollutants are a global concern. Assessing the fate and transport of NPS pollutants both in real time and from model simulations is crucial to understanding cause-and-effect relationships and for synthesizing current knowledge into a useable form for policy decisions. However, modeling NPS pollutants is a complex multi-disciplinary problem requiring a systems-based approach within a spatial context with an awareness of scale. It is the objective of this encyclopedia article to provide a general discussion of the 3 components of a NPS pollutant model: data, geographic information system (GIS), and model. Each component is discussed from a systems-based perspective to provide an understanding of their interaction and interdependence. Because temporal and spatial scale determines the construct of a NPS pollution model, the theory of hierarchical scales is presented. It is concluded that the future success of landscape-scale environmental modeling rests not on enhancing the detail of model structure, but rather on characterizing the spatio-temporal variability of model inputs and parameters.