The EPA model Pesticide Root Zone Model (version 5.0) is used to estimate off-field loadings of pesticide concentrations in runoff and eroded sediment. Climate change has resulted in an increase in rainfall intensity patterns for much of the U.S. which makes both the PRZM5.0 “lookup “ table for runoff curve numbers and the internal algorithm for eroded sediment estimation outdated. This paper will present (1) a revised method for estimating runoff curve numbers that reflect current rainfall intensity patterns; (2) a revised PRZM5.0 version that has an updated erosion algorithm that includes updated coefficients for rainfall intensity based on the 2014 NRCS NOAA EFH-14 system and (3) examination of the effect of these revisions for six EPA standard environmental modeling scenarios and three example pesticides compared to current practices.

Revisions to PRZM5.0 runoff methods and erosion algorithms to reflect current rainfall intensity patterns

254th National Meeting (2017)

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