Ghani Akbar

HYDRAULIC PERFORMANCE OF RAINGUN SPRINKLER IRRIGATION SYSTEM USING LOW CAPACITY DUGWELL

This research work was carried out at Phularwan Research Farm of the Mona Reclamation Experimental Project, WAPDA, at Tehsil Bhalwal of Sargodha district. Raingun (PY,-30) was operated with 12-mm and 10-mm nozzle sizes. Water source was a dugwell whose recharge rate was very less. Thus steady state could not be obtained as the discharge exceeded the recharge rate during pumping. The effect of continuous fall of water level in the dugwell on the performance of raingun sprinkler irrigation system was evaluated. Relationships were developed between various parameters affecting the performance of the system. Discharge, pressure and radius of raingun throw decreased with the fall of water level in the dugwell. These variations in the values of various parameters adversely affected the application rate and water distribution uniformity of the raingun sprinkler irrigation system. The reduction in size of nozzle with the fall of water level in the dugwell has caused some improvements. The coefficient of uniformity values increased toward the center of the wetted area. The hydraulic gradient was found very steep near the dugwell, which has reduced the radius of influence of the dugwell. The reason for slow recharge rate was found to be the clogged screen section of the dugwell as it had been abandoned for more than thirty years and tight brick lining having no perforations. Application rate increased with time ofpumping as the wetted area decreased due to reduction in radius of raingun throw.