An analysis of water consumption rates in agricultural irrigation systems

To provide a background for the discussion of the high water consumption rates found in irrigation systems which use projectile-type sprinkler heads, the history and evolution of irrigation systems is discussed. The effect of evaporation is studied as as explanation for the water losses, but it is found to be insignificant. Having discovered that evaporation is negligible, air motion caused by either wind or entrainment resulting from water droplets is examined. Data resulting from a two dimensional model which uses Seginer's equations of droplet motion showed that air movement is a major cause of water consumption. To give a more realistic set of results, a three dimensional model which describes the water loss from the center-pivot and lateral move irrigation systems is used. Again it is found that wind and entrainment effects result in significant water losses.