AN EXPERT-SYSTEMS APPROACH FOR ASSESSING THE POTENTIAL FOR PESTICIDE CONTAMINATION OF GROUND-WATER

The EXPRES expert system (EXpert system for Pesticide Regulatory Evaluations and Simulations) has been developed to assist those who are knowledgeable, but not proficient, in the theory of pesticide transport in the subsurface or in the use of pesticide assessment models with a means of assessing the potential for pesticides to contaminate ground water. EXPRES is not intended to replace expert opinion but rather EXPRES is intended to be used as a screening tool by nonexperts who need to evaluate the potential for pesticides to contaminate ground water. EXPRES combines a knowledge-based system, a graphically based user-system interface, extensive geographical and pesticide data bases, and three existing pesticide assessment models (LP/LI, PRZM, and LEACHM). Based on the user's available data, objectives of the assessment and time constraints, EXPRES selects the most appropriate model, assists the user in the construction of an input data set, initiates an assessment, and aids in the interpretation of the results of an assessment model. Specific assistance in the construction of the input data set includes providing pertinent data for characterizing a site or a pesticide from its data bases, assisting the user to respond to a prompt from EXPRES, aiding the user in estimating missing values for pesticide or site parameters, and ensuring the integrity of the input data set. The inclusion of three models allows EXPRES to select the model which is most applicable for the objectives on the investigation, including: (1) a review of pesticide properties and site characteristics that influence the fate of pesticides in the subsurface, (2) a relative assessment, with respect to other pesticides, of the potential for a pesticide to leach to the water table, (3) a quantitative prediction of the distribution and migration rates of the pesticide with both time and depth, and (4) an evaluation of the processes and factors controlling the fate of the pesticides in the subsurface.