Submitted to: Hydrogis Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/15/1996
Publication Date: N/A
Technical Abstract: A strategy for estimating ground water vulnerability to agricultural chemicals was developed using georeferenced data and a one-dimensional leaching model. The strategy includes: 1) Identifying characteristics of ground water resources for classification; 2) Mapping aquifer classes using environmental characterization data in a geographic information system (GIS); and 3) Estimating the occurrence of a contaminant by applying a one-dimensional model to representative conditions in each class. Principal data sources are the State Soil Geographic Data Base (STATSGO), National Resources Inventory (NRI) and a soil attribute data base (SOILS5). Variables from SOILS5 were used to define alluvial aquifers, other unconsolidated aquifers, and bedrock aquifers. ARC/INFO coverages will be used to map the boundaries of near-surface aquifer classes; alluvial, other unconsolidated, and bedrock. The aquifer boundaries will be intersected with the NRI, identifying points that lie within each aquifer class. Points will be selected in each subset using a stratified random procedure to obtain a representative samples of soils associated with each class of aquifers and their geographic distribution. Soil and management data at each representative point will be used in the pesticide root zone model (PRZM-2) to devine a regression metamodel to be used to estimate atrazine concentrations at all NRI points in each aquifer class. Model results will be compared to data from a regional survey of wells penetrating shallow aquifers in the region. A robust strategy to estimate ground water vulnerability to agricultural chemical sources will be important to evaluate proposed or contemplated changes in agricultural practices and land use.