Publication Date


Series Number

99-WP 215


The Erosion Productivity Impact Calculator (EPIC) model is validated using long-term data collected for two southwest Iowa watersheds that have been cropped in continuous corn under two different tillage systems. The annual hydrologic balance was calibrated during 1988-94 by adjusting the runoff curve numbers and residue effects on soil evaporation. Model validation was performed for 1976-87 using both summary statistics and parametric and nonparametric statistical tests. Overall, results show that EPIC was able to replicate the long-term relative differences between the two tillage systems.

Publication Information

This working paper was published as Chung, S. W., P. W. Gassman, L. A. Kramer, J. R. Williams and R. Gu, "Validation of EPIC for Two Watersheds in Southwest Iowa," Journal of Environmental Quality 28 (1999): 971–979, doi:10.2134/jeq1999.00472425002800030030x.