A non-point source pollution management model, ANSWERS-2000, was devel
oped to simulate long-term average annual runoff and sediment yield fr
om agricultural watersheds. The model is based on the event-based ANSW
ERS model and is intended for use without calibration. The physically
based Green-Ampt infiltration equation was incorporated into ANSWERS-2
000 to improve estimates of infiltration. An evapotranspiration submod
el was added to permit long-term, continuous simulation. The model was
validated without calibration using data from the field-sized P2 and
P4 watersheds in Watkinsville, Ga. Additional validation with limited
calibration was done on the Owl Run watershed in Virginia. Model predi
ctions of cumulative sediment yield were within 12% and 68% of observe
d values. Predicted cumulative runoff volumes ranged from 3% to 35% of
observed values. Predictions of sediment yield and runoff volume for
individual storms were less accurate, but generally within 200% of obs
erved values. In a practical application, the use of the model in agri
cultural non-point-source pollution control planning was demonstrated.