STATISTICAL APPROACH TO INCORPORATING THE INFLUENCE OF LAND-GRADING PRECISION ON LEVEL-BASIN PERFORMANCE
Monte-Carlo simulation was used to determine the suitability of statistical equations for estimating the 
influence of soil surface elevations on the low-quarter distribution uniformity, DUlq, of level-basin irrigation systems. It 
was shown that these equations give reasonable estimates of DUlq, provided that the advance curve is known. The Monte- 
Carlo simulations also provided an estimate of the variation in DUlq for different fields with the same standard deviation 
of elevations. The statistical equations demonstrate that irrigation uniformity is influenced by the ratio of soil surface 
elevation standard deviation to average depth infiltrated. For conditions that would be typical of laser-leveled basins 
within the U.S., the influence of elevation variations on DUlq is small. However, for poorly leveled fields, as frequently 
occur in Egypt, these elevation variations can significantly reduce DUlq, thus limiting potential efficiencies. In some 
cases, these simple equations can be used to adjust level-basin designs to account for the variation in surface elevations 
without the need for extensive simulation studies.