A GIS-BASED MODELING APPROACH FOR EVALUATING GROUNDWATER VULNERABILITY TO PESTICIDES1

Authors

  • S. Shukia,

  • S. Mostaghimi,

  • V O. Shanholtz,

  • M. C. Collins

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    • 2

      Respectively, Graduate Research Assistant and Professor, Department of Biological Systems Engineering, Seitz Hall, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24060; Former Professor and President, MapTech Inc., Virginia Tech Corporate Research Center, Suite 2220, 2000 Kraft Drive, Blacksburg, Virginia 24060; and Environmental Planner, Thomas Jefferson Planning District Commission, 300 Main Street, P.O. Box 1505, Charlottesville, Virginia 22902 (E-MaillMostaghimi: smostagh@vt.edu).


  • 1

    Paper No. 97072 of the Journal of the American Water Resources Association.Discussions are open until August 1, 1999.

Abstract

ABSTRACT: The Attenuation Factor (AF), a screening model, was used to evaluate the relative degree of vulnerability of groundwater to pesticide contamination in Louisa County, Virginia. For evaluating the contamination potential of pesticides, three scenarios of pesticide leaching represented by high, moderate, and low cases of degradation and sorption in the soil were considered. Data layers were overlaid within a Geographic Information System (GIS) for spatial computation of AF for the actual and 2m groundwater depths. This spatial database was divided into five contamination potential categories namely high, medium, low, very low, and unlikely, based on the numerical values of the AF for each cell (119 ha). The results for the three most mobile pesticides are presented in this paper. The performance of the AF model was evaluated by comparing its predicted results with the field data from an experimental watershed. The AF model was able to identify most of the frequently detected pesticides in the watershed. A sensitivity analysis was also performed. The results of this study provide information about the potential groundwater threat by pesticides to the citizens ahd decision-makers in the County and can be used for formulating an appropriate land use management plan to protect the groundwater quality.

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