Comparison of leaching predictions based on PRZM3.12, LEACHP, and RZWQM98 using standard scenario modeling.

Regulatory agencies in the NAFTA region use ground water leaching models to help determine risks to ground water resources. The results of three models for leaching predictions are compared using a standard soil and weather scenario currently used by the New York Department of Environmental Conservation (NYDEC) to simulate the Riverhead soil found on Long Island, New York. The three models, PRZM3.12, LEACHP, and RZWQM98, were configured to simulate the behavior of two example molecules in corn, turfgrass, and bare soil. For the bare soil simulations, LEACHP and RZWQM98 predicted similar peak concentrations and timing of peak concentration. Depending on the dissipation rate of the molecule, PRZM3.12 predicted similar to reduced peak concentrations due to the delayed timing to reach the peak concentration. For the corn and turfgrass simulations, peak concentrations and timing to reach peak concentrations varied between the models due to differences in how each simulates plant growth and evapotranspiration.