ABSTRACT A computer simulation model was used to compare the effect of sprinkler spacing and terrain on the theoretical performance of six center pivots. Systems with impact sprinklers and low pressure fixed head spray sprinklers had the highest uniformities for constant spacings of 12 and 1.5 m, respectively. Energy use was highest on upward sloping terrains. Spray systems used 30% less energy and had higher mean and peak application rates than a system with impact sprinklers.