Hydraulic performance evaluation of drip irrigation system with different emission devices
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Date
2005
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Abstract
Studies were conducted to evaluate the effect of operating pressure
head and spacing on different hydraulic performance evaluation measures of drip
irrigation systems with different emission devices. The commonly used hydraulic
performance evaluation measures considered were uniformity coefficient, emission
uniformity, coefficient of variation and coefficient of manufacturing variation. The
different emission devices were dripper, micro-tube, drip-in and drip tape. The
experiments were conducted in the field laboratory of Soil and Water Engineering
Department, College of Agricultural Engineering and Technology, CCS Haryana
Agricultural University, Hisar. The selected spacings were i) 6m x 6m, 1m x 6m and
0.5m x 0.5m for dripper and micro-tube, ii) 6m x 0.6m, 1m x 0.6m and 0.5m x 0.6m
for drip-in and iii) 6m x 0.3m, 1m x 0.3m and 0.5m x 0.3m for drip tape. The
operating pressure heads were 5m, 10m and 13m.
The measurement of discharge for calculation of hydraulic performance
evaluation measures was done by operating the system and putting the containers at
6m interval along the lateral lines. The measurement of pressure head was done with
the help of mercury manometer and water manometer at up stream and down stream
end of main line and lateral line. The values of different hydraulic performance
evaluation measures and head loss in main line and lateral line were calculated. The
values of uniformity coefficient and emission uniformity decreased for dripper and
micro-tube and increased for drip-in and rip tape, as the spacing decreased. The
values of uniformity coefficient and emission uniformity for all emission devices
increased as the operating pressure head increased at a particular spacing. The
values of coefficient of variation increased for dripper and micro-tube and decreased
for drip-in and drip tape, as the spacing decreased. The values of coefficient of
variation for all emission devices decreased as the operating pressure head increased
at a particular spacing. The values of coefficient of manufacturing variation was
maximum for drip tape and minimum for micro-tube. The values of head loss in main
line and lateral line for different emission devices increased as the spacing decreased
and increased as the operating pressure head increased. The head loss in the main
line and lateral line also increased at a decreasing rate with discharge and the
variation can be expressed with a power equation. The values of the coefficients in the
power relationship between head loss and discharge were calculated for each emission
device and also combined for all emission devices. The coefficient of correlation for the
combined equation was 0.9871 for main line and 0.7201 for lateral line. A computer
software in C++ language was developed for calculation of the hydraulic performance
evaluation measures and head loss in main line and lateral line of system. The values
obtained from the computer software were equal to the measured values.