Keywords: GLEAMS, groundwater risks, risk assessment, NAPRA WWW, nutrient contamination, risk analysis, web-based GIS, geographical information systems, pesticide risks, nitrate, atrazine, water pollution, water quality, agriculture, pesticide contamination
Identifying regional groundwater risk areas using a WWW GIS model system
To evaluate the National Agricultural Pesticide Risk Analysis (NAPRA) WWW system (http://pasture.ecn.purdue.edu/~napra), NAPRA WWW predicted nitrate and atrazine losses to shallow groundwater were compared with well nitrate and atrazine data within Indiana. The NAPRA system correctly categorised 84% of the 'High' and 'Very High' nitrate observations, although the predicted nitrate losses are generally in more severe categories than measured nitrate levels. The NAPRA system also correctly categorised 69% of the 'High' and 'Very High' atrazine observations. Predicted results match measured concentrations reasonably, if assumptions and limitations of the NAPRA WWW system are considered. This system has the potential to identify areas vulnerable to nitrate and atrazine groundwater pollution. Thus, a web GIS version of the NAPRA model was developed (http://pasture.ecn.purdue.edu/~napra/NAPRA_SPATIAL) to facilitate the assessment of the effects of more refined agricultural management on water quality at farm field scales.