| dc.description.abstract | This study was to evaluate the technical performance of
Kibirigwi sprinkler irrigation system in the Upper Tana
Basin, Kenya. Development of irrigation in this area is
constrained by water availability and not land availability.
The available water resources therefore need to be utilized
as efficiently as possible. In this study, some shortcomings
in, crop water management practices in the scheme, System
maintenance resulting mainly to pressures and water losses
in the system and low sprinkler performance efficiencies.
On average, the christiansen uniformity coefficient was 77
percent, sprinkler application efficiency was 70 percent,
distribution uniformity was 64 percent, potential
application efficiency of the low quarter was 65 percent and
the application efficiency of the low quarter was 56
percent. The pressures and discharge imbalances in the
system were caused by multiple leakages in the distribution
network, mainly at the control valves, pipe junctions,
hydrants and connections of the portable irrigation
equipments at the farms. Irrigation water was insufficiently
filtered and the remaining sediments had caused sprinkler
nozzle diameters to wear by an average of 9.1 percent.
An alternative irrigation schedule responsive to the
prevailing weather conditions and the type of crop growing
in the season was proposed. This was to replace the
existing schedule of an application duration of 10 hours and
an irrigation interval of 7 days for all the crops. If
farmers would follow the developed irrigation schedule in
this study and in addition have pipe leaks in the
distribution network, at the gate valves and at pipe
connections at the farms repaired, the irrigation efficiency
of the scheme would greatly improve.
Though the scheme experiences water shortages during some
periods in the year, the shortages cannot be attributed to
inadequate river discharge during these periods. River flow
analysis showed that the water flowing past the water
abstraction point was much higher than the required scheme
irrigation discharge throughout the year. | en |
