Evaluating The Effect Of Drag line Sprinkler Operating Pressure, Riser Height, Nozzle Size And Wind Velocity On Irrigation Water Application Under Different Wind Speed Conditions; The Case Of Tedecha Large Scale Irrigation Scheme.

Abstract

The worldwide climate change and its incidental effect on scarce water resources have further reduced the amount of water available for agriculture. Owing to an increasing demand for irrigation water associated with the remarkable expansion of sugarcane irrigation schemes in Ethiopia, there is a desire to use the available water efficiently and effectively. Under this circumstance, the use of pressurized irrigation systems can be an alternative for enhancing the efficiency of water consumption. Hence, a study was conducted to evaluate the effect of riser height, nozzle size, operating pressure and wind velocity on irrigation water application of new dragline sprinkler system at Tedecha large scale irrigation scheme, Bofa. The study was conducted under five wind phases (morning, mid-day, afternoon, early and late night) where wind speed is expected to vary using four levels of riser height, three levels of operating pressures and two levels of nozzle sizes. Catch can test were carried out for uniformity measurement using four sprinklers configurations. Results of the field evaluation indicated that the average evaporation and wind drift losses (E %) range from 3.33% to 13.65% in the morning, 8.63 to 19.90% in the mid-day,6.85% to 17.12% in the late afternoon, 2.98% to 13.01% in the early night and 2.04% to 11.56% in the late night, PAE range from 51% to 93%, PELQ of 25.7 % to 78.3, AELQ of 24.2% to 69.1%, CU range from 59.5% to 90% and DU range from 55% to 87.2% were achieved under different test combinations. DPR and WIP range from 0.75 to 1.22 and 0.59 to 1.53 was obtained under different test combinations, respectively. Emanating from the experimental results were most of the combinations failed to meet the expected values in all parameter and lower operating pressure and higher wind velocity were the major factors responsible for the low water distribution uniformity and efficiency. It?��?s recommended that the out growers should rehearse night time rather than day time by applying the best combinations of optimum operating pressure (3.0 bar) for 4.