Doctor of Philosophy (PhD)


Environmental Sciences

Document Type



The Environmental Protection Agency (EPA) model Pesticide Root Zone Model, version 5.0 (PRZM5.0) 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 United States. This change impacts off-field runoff and eroded sediment as well as off-field pesticide loads from agricultural fields. Thus, the PRZM5.0 EPA “lookup” table for runoff curve numbers and the internal algorithm for eroded sediment estimation have become outdated since both temporal and geographical conditions have changed. This research presents (1) a revised method for estimating runoff curve numbers that better represent current rainfall intensity patterns as well as more geographically representative based on the Natural Resources Conservation Service (NRCS) single event method for estimating runoff curve numbers; (2) a revised PRZM5.0 version with a modified erosion algorithm that includes empirical coefficients from an 2014 NRCS updated storm intensity system and (3) examination of the effect of these PRZM5.0 revisions for six EPA standard environmental crop modelling scenarios and three example pesticides compared to the established EPA practices.



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Committee Chair

Armbrust, Kevin L.