Drop Size Distribution as Influenced by Operating Pressure and Riser Elevation in Sprinkler Irrigation

摘要

Sprinkler irrigation is an advance method of irrigation through which water can be used effectively. However in the field, sprinkler irrigation is also associated with problems like water loss due to wind drift &andevaporation, distortion of application pattern by wind and modification of infiltration characteristics of the soil by impact of drops on the soil surface. These problems are associated with the movement and physical condition of individual droplets sprinkled through the system. As a stepto explore the solution to some of the above problems, a field investigation was conducted to determine drop size distribution from rotary sprinkler and to study the effect of operating pressure and nozzle elevation on it. Drop size distribution was determined at three operating pressures i.e. 2.5, 2.0 and 1.5 kg/cm~2 with three nozzle elevations 150, 110 and 75 cm for 5.6,4.7 and 3.1 mm nozzle size. Flour method as suggested by Dadio and Wallender (1985) was used for determination of droplet diameter.As per the results of the field study, it was analyzed that droplet diameter increased as the distance increased from the sprinkler. Droplet diameter, as well as range of droplet diameter from minimum to maximum decreased with increase in nozzle elevation and relatively larger number of droplets and high value of cumulative volume per cent were found at 2.5 kg/cm~2 pressure spray as compared to that of 2.0 and 1.5 kg/cm~2 operating pressure. Relative change in drop size distribution at 2.5 kg/cm~2 operating pressure due to hammer spray occurred near the sprinkler with a decrease in nozzle elevation. It was also found that nozzle elevation had a minimum effect on drop size, but operating pressure had a significant inverse influence.