Uniform Water Distribution From Low Pressure Rotating Sprinklers

Abstract

Population of India has probably crossed 1150 million marks by the end of 2007 (Survey of Indian Agriculture 2007). The estimated requirement of food grains by 2020 will be 307.75 million tonnes to meet the balanced diet norms prescribed by Indian Council of Medical Research. In 2007, the production of food grains was only 212.62 million tonnes. The gap of 95.13 million tonnes has to be narrowed down by adopting modern scientific approaches for efficient management of scarce land and water resources at a sustainable manner.

Sprinkler irrigation is one of the modern scientific approaches which is becoming more and more popular in India in regions of water scarcity where available water is insufficient to irrigate the command area by surface irrigation. Uniformity of water distribution at four different nozzle pressures and three different spacing was studied for both plastic and brass type of sprinklers. The deviation of uniformity coefficient of plastic sprinklers from that of brass sprinklers was found to be from 0 to 2 %. It was also observed that optimum uniformity of water distribution was obtained at a nozzle pressure of 2.0 kgf/cm2 in normal windy condition. The uniformity of water distribution decreased with the increase of nozzle pressure beyond 2.0 kgf/cm2 for small and medium size nozzles.

Comparison was made among different sprinklers and lateral spacing of 6.1 m x 6.1 m, 6.1 m x 12.2 m and 12.2 m x 12.2 m. It was observed that the spacing of 6.1 m x 6.1 m gives better distribution for low pressure sprinklers for all combinations of nozzle pressures and sizes. It was recommended to operate the low pressure sprinklers at a sprinkler and lateral spacing of 30 % of the spray diameter. It was also observed that the effect of wind velocity on uniformity of water distribution was less for wind velocities below 4 km/h and moderate for wind velocity below 7 km/h and the distribution pattern gets distorted at high wind velocity of 15 km/h.