CONVEYANCE AND WATER USE EFFICIENCY IN THIRTY YEARS OLD  IRRIGATION SCHEME: ESTABLISHING BASELINE INFORMATION TO  REVITALIZE THE MEKI-ZIWAY IRRIGATION SCHEME
Creators: name: MUSSIE ALEMAYEHU YIBLETAL
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2016

description: Meki-Ziway Irrigation Scheme is a pumped-gravity irrigation scheme established in 
1986. The scheme is currently characterized by poor on-farm and off-farm irrigation 
water management. Irrigation performance assessment has not been carried out for 
Meki-Ziway irrigation scheme in Ethiopia since its operation. In this study,  the 
conveyance system and irrigation practice was evaluated at field level.  
The  main pump discharge was measured in two ways, (i) by measuring the duration 
which is required to fill the stilling basin: (ii) using current meter to measure the velocity 
of the water. The conveyance efficiency of the main canal was determined by estimating 
discharge at  three  reaches. On farm  field application was  evaluated in four farm plots 
with three replicas in each plot. Furrow inflow rate, cutoff time and soil moisture content 
in the root zone of crops was monitored. Inflow rate was measured using bucket method 
while soil moisture content before and after irrigation application was measured by using 
a portable soil moisture sensor. The soil moisture also monitored at daily time intervals 
over a period of 25 days. The instrument was calibrated by laboratory result.  The 
monitoring  was  conducted in two periods: in a time when there was a better water 
availability and in a time when there was water scarcity. The extent, need and effect of 
new water users were investigated through household survey  and necessary data 
measurement. These new users were not a part of the scheme originally.  
The result shows that the main pump is being operated at a mean discharge of 512.046 
l/s. the mean conveyance efficiency of the main canal is 43.83% while the efficiency of the 
secondary canal is 89.72%. Many of the secondary and tertiary canals are poorly 
maintained and many of the structures are dysfunctional. The study result also shows that 
only 45.44% to 74.24% (mean value 58.06%) of the applied irrigation water amount is 
stored in the crop root zone while the remaining is lost by deep percolation and runoff. 
The result varies across farm plots, replicas and irrigation event.  
Analysis of the continuous soil moisture records indicates that amount of water stored  in 
the rote zone varies with the location of the farm plots. Farm plots at the canal head, 
which have good access to water, were mostly irrigated up to the soil saturation level and 
their moisture level hardly drops below the permanent wilting point. For farm plots which 
are located far from the canal head, the soil moisture content drops below the permanent 
wilting point for a number of consecutive days due to limited access to irrigation water. 
There is no appropriate water allocation system in the scheme  that would ensure equity 
across the reaches.  
Overall, there is a strong need to rehabilitate the physical infrastructure of the scheme by 
considering the new users  and enhance farmer’s knowledge of crop yield response to 
water application. Future interventions should provide incentives to farmers to improve 
the current irrigation efficiency levels.  There should introduce appropriate water 
allocation system in the scheme that would ensure equity across the reaches