Sprinkler systems application uniformity and energy conservation
Experiments were conducted on single sprinklers (impacts, rotators and fixed spray) and sprinkler irrigation systems (centre pivot and linear move) to determine their energy usage, uniformity coefficient (UC), distribution uniformity (DU), application efficiency of the low-quarter (AELQ), application efficiency (AE), and the effect of wind on these parameters. The single sprinklers were operated at different pressures and heights. For the single sprinklers the energy use increased with increasing operating pressure at the sprinkler. There was a slight increase in energy use with increase in height, although the energy use increase was not significant. In some cases the energy use was similar at different heights. The uniformity coefficient for the single sprinklers decreased with increasing overlapped spacings. The uc also exhibited random variations with overlapped spacings. Pressure had a significant effect on the uc for the impact and fixed spray sprinklers. The effect of pressure on the rotator sprinklers was not significant. Sprinkler height had an effect on the UC for the fixed spray and in some cases the rotators. Higher values of DU and AELQ can be achieved by the single sprinklers if the uniformity coefficients are higher. High average wind speeds distorted the distribution patterns of the single sprinklers producing low values of uc, DU, AELQ and application efficiency. Different uc, DU and AELQ values were achieved for the same average wind speeds. In some cases higher average wind speeds produced higher UC, DU and AELQ but lower application efficiencies. For the sprinkler irrigation systems the centre pivot system produced higher uc, DU and AELQ compared to the linear move irrigation systems. The Reinke linear move (RLM) irrigation system produced good UC and DU compared to the Valley linear move (VLM) irrigation system. Energy use increased with increasing operating pressure and flowrate at the inlet for the linear move and the centre pivot irrigation systems. The RLM system used less energy compared to the VLM irrigation system. Wind affected the uc, DU, AELQ and application efficiency of the sprinkler irrigation systems. Depending on the wind speed and direction, the distribution patterns of the irrigation systems were distorted to either produce a higher or a lower UC, DU, AELQ and application efficiency. Shelter belts reduced the effect of wind on the distribution patterns improving uc, DU, AELQ and application efficiency.