PERFORMANCE EVALUATION OF CENTER PIVOT SPRINKLER IRRIGATION SYSTEM: CASE STUDY ON HIWOT AGRICULTURAL MECHANIZATION, ETHIOPIA

Abstract

Performance evaluation of center pivot sprinkler irrigation system installed at Hiwot Agricultural Mechanization farm was conducted. The existing irrigation system and agricultural practices were studied and measurements of the water application uniformity indicators were made and performance gaps were identified. HAM farm has 32 center pivot machines, out of which only five center pivot machines were under operation at the time of the present study. Radial measurements of water application along the CP sprinkler irrigation system lateral line were made for the estimation of coefficient of uniformity, distribution uniformity, and potential application efficiency of low quarter. Catch cans were placed along the CP lateral at 3m spacing for collection of water application along the lateral of center pivot. The measurement were made at five location s identified by the number of CP irrigation machine, m4, m6, m7, m8, and m12. Three of the locations were at upstream (m8, m12, and m4) and two located in middle (m6 and m7) of HAM farm. The measurements at location m4 were made twice, day time (about 2 pm) and night time (about 9 p m), however, for the remaining locations measurements were made only during day time. The measured value of water application rate for different locations along center pivot lateral line varied widely, generally lower values at pivot and higher values at end of center pivot lateral line. The Distribution uniformity, coefficient of uniformity and potential application efficiency of low quarter were varied from 67% to 85%, 73% to 86%, and 66% to 80% respectively. The highest value of DU was at night time measurement for location m4 as compared with m4 at day time due to lower wind velocity during night time (1.5m/s) and lowest value was for location m7. The highest value of CU was at location m7 whereas the lowest value was for location m12. The application rate at all the location was higher as compared to basic infiltration. The measured values of irrigation efficiency at different locations varied from 60 % at location m7 to 69% at location m6. The highest value of crop water requirement at location m6, m7 and m12 was 5.24 mm/day in September at mid stage and for location m4 and m8 in October at mid stage equal to 4.99 mm/day. Whereas, the lowest crop water requirement at location m6, m7 and m12 was 2.52 mm/day in July at initial stage which was and for location m4 and m8 in august at initial stage equal to 2.08 mm/day