Open Access Journal

Journal of Sustainable Research in Engineering Vol. 5 (2) 2019, 101-112

Journal homepage: http://sri.jkuat.ac.ke/ojs/index.php/sri
ISSN (Online): 2409-1243

Hydraulic performance evaluation of the water

conveyance system of Doho Rice Irrigation Scheme
in Uganda
Erion Bwambale1*, Patrick G. Home2, James M. Raude2, and Joshua Wanyama3

1
Civil Engineering Department, Pan African University Institute for Basic Sciences, Technology, and Innovation
(PAUISTI), P. O. Box 62000-00200, Nairobi, Kenya
2
Soil, Water and Environmental Engineering Department, Jomo Kenyatta University of Agriculture and
Technology (JKUAT), P. O. Box 62000-00200, Nairobi, Kenya;
3
Agricultural and Bio-Systems Engineering Department, Makerere University, P. O. Box 7062, Kampala, Uganda.
*
Corresponding Author - E-mail: erionbwambs20@gmail.com

Abstract
Poor water distribution is a major problem in many surface irrigation schemes in Uganda, especially at the tail reaches. This has
led to reduced crop yield from these water-stressed fields. This study reports the results of evaluating the hydraulic performance
of the water conveyance system of Doho Rice Irrigation Scheme for one cropping season for the first quarter of 2019. For the main
canal, the conveyance efficiency indicator was used while for the lateral canals indicators of adequacy, efficiency, dependability,
equity, and the equity ratio of head to tail were used to evaluate the hydraulic performance. Performance indicators were computed
at the head and tail ends of the canals thus comparing the inlet and distribution processes. Field measurements coupled with
simulation techniques were used to obtain the delivered and required flows. It was found that the acceptable average hydraulic
performance indicators of the scheme were 0.84, 0.79, 0.07 and 0.26 for adequacy, efficiency, dependability, and equity
respectively, the tail reaches suffer in performance with the adequacy, dependability, and equity ratio at 0.68, 0.12, and 3.13
respectively. Improving hydraulic performance of the scheme necessitates reduction of water conveyance losses, adherence to
distribution plans and monitoring of diversions to the canals..

Keywords: Conveyance; Efficiency; Evaluation; Hydraulic performance; Indicators

to [4], 60% of the world’s freshwater diverted for

1. Introduction
agriculture does not contribute directly to food
Irrigation development has gained significant importance production. Losses stem from poor on-farm water
across the globe because of its potential to improve food management practices, water leakage along the
security and reduce rural poverty [1]. The Agricultural conveyance system, and obsolete control structures. The
sector in Uganda contributes about 24.6% of the gross productivity of irrigated lands in Africa can only be
domestic product (GDP), provides a livelihood for over increased and sustained by periodical performance
72% of the economically active population, and supplies evaluation [5].
most of the raw materials for agro-processing industries Performance evaluation of an irrigation system can be
[2]. Agriculture is responsible for, on average, 70 percent defined as the systematic observation, documentation,
of all water withdrawals worldwide, and an even greater and interpretation of activities related to irrigated
share of consumptive water use owed to the agriculture with the objective of continuous improvement
evapotranspiration requirements of crops [3]. According
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[6]-[7]. The ultimate purpose of performance evaluation efficiencies and thus for the main canal of Doho Rice
is to attain an efficient and effective use of resources by Irrigation Scheme, the conveyance efficiency indicator
providing relevant responses to management at all levels was used for evaluation.
[8]. According to [9], performance assessment evaluates A water delivery system that is not adequate,
the existing situation of irrigation performance, identifies dependable, equitable or efficient can have adverse
the constraints to proper performance, and implements effects on crop productivity in the irrigation scheme.
management interventions to improve the Timely information on performance related metrics (e.g.
performanceTherefore, in an irrigation scheme, hydraulic water delivery, drainage control, water shortage) is
performance evaluation contributes to system required by the operational managers on time to make
management in determining whether the performance is relevant decisions in regard to water allocation,
satisfactory and, if not, which counteractive actions need maintenance, and modernization plans and cropping
to be employed in order to remedy the status quo [8]. Low systems [7].
levels of hydraulic performance are common on many
2. Materials and methods
surface irrigation schemes in sub-Saharan Africa [10].
Factors contributing to low hydraulic performance in 2.1 Description of the study area
large scale irrigation schemes in sub-Saharan Africa Doho Rice Irrigation Scheme spans in both Mazimasa and
range from canal sedimentation, inadequate institutional Kachonga Sub-Counties of East Bunyole County in
setup, deteriorating infrastructure and poor water Butaleja District of Uganda as shown in Fig 1. It is located
management [11]-[12]. As a result, there have been at Longitude 34°02’ East of the Greenwich and Latitude
conflicting opinions about further investments directed 0° 56’ North of the Equator on the right bank of Manafwa
towards new irrigation projects, primarily due to the River. It is 49 km from Tororo town, 25 km from Mbale
questions about the performance of existing projects [10]- town and 260 km from Kampala city and 70 km from
[13]. Malaba, Uganda-Kenya border. Doho Rice Scheme is
Hydraulic performance evaluation has not been located in the Lake Kyoga basin and covers an area of
incorporated in the monitoring and evaluation framework 494.2 km2 [19]. The scheme covers an area of 2500 acres
of public irrigation schemes in Uganda despite it being a (1000 Ha), 2380 of which is cultivated while the
tool for determining performance of the water delivery remaining 120 acres are covered by irrigation
and control systems within the scheme [14]-[15]. In a infrastructures like farm roads, embankment, water
study conducted by [16] to determine the household conveyance channels, and bridges. The Scheme is
contribution to irrigation management, farmers’ refusal to partitioned into 11 main blocks namely: 1A, 1B, 2A, 2B,
pay for irrigation water was reported which has led to 3, 4A, 4B, 5A, 5B.6A, and 6B as shown in Fig 2. This
reduced rice yields at the tail reaches [17]. Although water division was made to create administrative units
delivery was qualitatively determined, this research purposely to ease management during water distribution
addresses this deficiency by quantitatively evaluating the [16]. The main canal which is unlined conveys irrigation
performance of the water conveyance system. water from River Manafwa to the scheme branches out
Quantitative determination of hydraulic performance into 2 secondary canals, the Southern canal, and the
indicators provides vital information to scheme managers Northern canal. The northern canal also acts as a drainage
necessary in decision making in regard to hydraulic channel for wastewater from the blocks and serves tail end
performance improvement. Poor water allocation blocks. From the secondary canals, water is conveyed
methods, deteriorating irrigation infrastructures, silted through lateral canals and then to the blocks. After
canals and lack of water measurement structures are the flowing through the paddy fields, water is collected in the
major challenges at Doho Rice Irrigation Scheme. The main drainage channel through the tertiary and sub-
effect of these challenges on hydraulic performance of the drainage channels and drained back into River Manafwa
water conveyance system were determined using [16]. Water distribution at Doho Rice Irrigation Scheme
performance indicators namely adequacy, equity, is done on a rotational basis amongst the canals where
efficiency, and dependability were used to evaluate the irrigation water is fed in a canal for a set time and then
performance of the conveyance system [7]. [18] closed until its turn comes around again.
suggested common efficiency terms for irrigation system
evaluation such as application efficiency, conveyance 2.2 Data Collection
efficiency, distribution uniformity, storage efficiency, Data was collected from primary and secondary sources.
runoff ratio, and deep percolation ratio. However, most of The primary data was collected through direct
the seepage losses, deep percolation and runoff are measurement from the field. Actual flows within the
considered by water conveyance and water application canals were measured at the headworks, Kapisa control

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gates, and in selected canals from the sampled blocks at 2.3 Actual irrigation water measurement
the head end, middle end and the tail end of the scheme In the study, flows were measured using a current meter.
as shown in Fig 2. Flows were measured five times in a The discharges were measured at two points along the
month for a period of 3 months from February to April main canal, and at 8 off-take canals located at the
2019. Comprehensive field observations and surveys headend, middle and tail ends. The flows were measured
were carried out to understand the irrigation practices, for 15 days in three months i.e. 5 days per month and
water distribution system and cropping patterns. Focused average monthly flows were calculated. Flows were
group and key informant interviews were conducted with measured following the procedure described in the WMO
irrigation attendants at Doho Rice Irrigation Scheme to Stream gauging manual No. 1044 [20]. Discharge along
understand the scheme water distribution schedule. The the main canal was measured at two points namely intake
secondary data was collected from Doho Rice Irrigation point and Kapisa intake gate. Flows in the secondary
Scheme offices, Ministry of Agriculture Animal Industry canal were measured at the diversion point from the main
and Fisheries (MAAIF), and Tororo Meteorological canal and at the point where it supplies a tertiary canal.
Station. From this data, information on actual cropping Flow measurements
patterns, command area, Scheme design document, and
climate data was obtained.

Kapisa gates

Figure 1: Study Area

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LAYOUT OF DOHO RICE IRRIGATION SCHEME

Figure 2: Layout of Doho Rice Irrigation Scheme

equation [21].
were taken at the head end, middle end, and the tail end
of the scheme. The discharge of the canal was computed 3.2 Hydraulic performance indicators
using the mean section method following ISO 748. The Hydraulic performance of the irrigation system was
total discharge (Q) at a section was determined as a sum evaluated using four indicators. These indicators were
of discharges in each subsection as in (1). evaluated using the data collected during the February to
 V  V  y  y  (1) April 2019 in one irrigation season. The main canal
Q  x 1Wx 
n x 1 x 1
x
 x
 system performance with respect to water delivery was
 2  2  estimated based on the monthly required and delivered
Where: discharge. Whereas at the field level, water delivery
performance was according to indicators of adequacy,
Q = total discharge (m3/s) dependability, equity, equity ratio for head to tail, and
W = width between two adjacent verticals (m) efficiency.
V = depth average velocity (m/s)
x = the number of verticals 3.2.1 Adequacy
y = flow depth (m) Adequacy of water is a measure of the degree to which
n = number of sections water deliveries meet soil-plant-water requirements [7]. It
3. Data processing and Analysis shows the ability of the system to reach targeted deliveries
Field data were first processed to obtain variables for in terms of quantity. Adequacy of water delivery is
calculating hydraulic performance indicators. dependent on water supply and the water demand by the
crops. Adequacy (PA) was calculated using (2) [22].
1 1 Q 
3.1 Crop water requirement PA     D
T T  S S QR
 (2)
The total volume of water needed to meet the 
evapotranspiration demand of the crops was estimated
using weather data and area under each crop for each Where:
season. Climate data was used to calculate monthly
potential evapotranspiration (ET0) using CROPWAT 8.0
software which is based on the Penman-Monteith

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 QD Efficiency Indicator, PF in terms of hydraulic performance

 Q QD  QR is defined as the degree to which water is conserved in the
PA   R
system. The conservation of water resources which plays
 an important role in water delivery for the authority and
 1 otherwise government because water saved may result in less
T  Time period (months) expenditure on infrastructure and can possibly be
S  Site where the canals are located allocated to fully meet the existing requirement or irrigate
more land. It is defined as the ratio of the volume of water
QD  The actual amount of water delivered (m3/s) required for a specific purpose to the volume of water
QR  Required discharge (m3/s) delivered for this purpose. The ratio is given as
1 1 Q 
3.2.2 Dependability PF     R
T
 (5)
According to [23], dependability deals with the quality of
T  S S QD 
the irrigation service rather than the quantity and it covers
both the reliability of discharges and timing of deliveries. where:
Dependability is defined as the temporal uniformity of the  QR
 Q QR  QD
ratio of the delivered amount of water to the required or
PF   D
scheduled amount. Dependability indicator (PD) is given

as [24].  1 otherwise
PF  is the spatial and temporal average of the
1 Q
PD  
S S
CVT D
QR (3)
ratio of QR/QD indicator over a region S
and time period T
Where: QD  The actual amount of water delivered (m3/s)
CVT  Temporal coefficient of variation of the ratio QR  Required discharge (m3/s)
QD/QR over a region S and a time T
3.2.5 Equity Ratio for Head and Tail
QD  The actual amount of water delivered (m3/s) Equity ratio for head and tail (ERHT) is both a
QR  Required discharge (m3/s) conveyance and water delivery indicator. It focusses on
the equity of water distribution for head and tail at
different levels of a system. It is expressed as
3.2.3 Equity
Equity, as related to water delivery system can be defined
1 t  n QD
as the delivery of the fair shares of water to the users
 headend 
throughout the system. Equitable water distribution is n t 1 QR
attained when the ratio of water delivered at head end to
ERHT  (6)
1 t  n QD
water delivered at tail end outlets is 1. A perfectly  tailend 
n t 1 QR
equitable distribution will result if all locations receive an
adequate water supply or if each location receives the Where:
same supply or what they are entitled to. Equity indicator
n = number of periods monitored
PE is given as [22].
1  QD  QD  The actual amount of water delivered (m3/s)
PE  
T T
CV S
  (4) QR  Required discharge (m3/s)
 QR 
Where:
3.2.6 Conveyance Efficiency
CV S  Spatial coefficient of variation of the ratio
The conveyance efficiency was employed for the main
QD/QR over a region S and a time T canal. It indicates how much water is lost along the canal.
QD  The actual amount of water delivered (m3/s) The conveyance efficiency was obtained using (7) [25].
QR  Required discharge (m3/s)

3.2.4 Efficiency Indicator

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Vm Qdes = design capacity of canal (m3/s)

Ec  *100 (7)
Q0
After computation of the indicators, the water delivery
canals are evaluated based on water delivery performance
where: indicators standards presented in Table 1 developed by
Vm = volume of water delivered to the [22].
distribution system (m3/s)
Q0 = amount of water abstracted from the
river (m3/s) 4. Results and Discussions
4.1 Hydraulic Performance Indicators
3.2.7 Delivery performance ratio
The amount of irrigation water supply can be evaluated Table 2 presents the discharges at various outlets QD and
using water delivery performance ratio (DPR). It is the the required flows QR to meet the crop water
ratio of the actual volume of delivered water to the requirements.
intended. [26] provided the use of average seasonal values
of the ratio of intended and actual volumes of water 4.1.1 Adequacy
delivered to the tertiary units in performance evaluation Results of the adequacy indicator of the selected canals at
of a secondary channel of an irrigation scheme. The Doho Rice Irrigation Scheme are presented in Table 3. Fig
delivery performance ratio allows determination of the 3 and Fig 4 present the temporal and spatial variability of
extent of actual water delivery during a selected period Adequacy indicator within the scheme respectively.
and at any location in the system [27]. It is obvious that if The adequacy indicator (PA) at Doho Rice Irrigation
the actual delivered volume of water is based on frequent Scheme has temporal values of 1.00, 0.84 and 0.68 at the
flow measurements, the greater the likelihood that head, middle and the tail ends of the system respectively.
managers can match actual flows to intended flows. To The spatial values of adequacy are 0.85, 0.78 and 0.89 in
obtain sufficiently accurate flow data, discharge February, March, and April 2019 respectively. The
measurement structures with water level recorders must adequacy indicator is measured against a standard by [22]
be available at key water delivery locations [6]. To presented in Table 1 where 0.9-1.0 is classified as good,
facilitate the handling of data, recorders that write data on 0.80-0.90 as fair and < 0.80 classified as poor. In March,
a chip are recommended [26]. DPR in irrigation system there is poor adequacy, crop water requirements were
indicates the problems related to sediment deposits, much greater than the water supplied by the canals. This
erosion, and vegetation of some water conveyance was because no rains were received in this month and
structures. Generally, delivery performance ratio is the hence less flows in the River Manafwa. The spatial
ratio of the amount of actual delivered to the intended variation of adequacy reduces from good to poor from the
amount of water to be delivered [26]. The ratio is given as headend to the tail end. This can be explained by two
shown in (8) by [9] ; factors. Supply was not well carried out in accordance
Qact with the crop water requirements in the different periods
DPR  (8) within the irrigation season. The average adequacy for the
Qdes scheme was 0.84 suggesting a fair distribution of
irrigation water among block.
where:
Qact
= actual flow in the canal (m3/s)

Table 1.Hydraulic performance indicators

Performance
Range
Indicators
Poor Fair Good
Adequacy <0.80 0.80-0.89 0.90-1.00
Dependability >0.20 0.11-0.20 0.00-0.10
Equity >0.25 0.11-0.25 0.00-0.10
Efficiency <0.70 0.70-0.84 0.85-1.00

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ERHT <0.7 0.7-0.79 0.8-0.9

Table 2. Delivered flows and Required flows in Canals

Location Canal Month QD(m3/s) QR(m3/s) QD/QR
Feb 0.040 0.024 1.000
LC 1A1 Mar 0.035 0.015 1.000
Apr 0.050 0.028 1.000
Head reach
Feb 0.035 0.010 1.000
LC 1A2 Mar 0.030 0.015 1.000
Apr 0.038 0.028 1.000
Feb 0.015 0.016 0.940
LC 4A Mar 0.050 0.069 0.720
Middle Apr 0.050 0.008 1.000
reach Feb 0.008 0.010 0.800
LC 4B Mar 0.012 0.016 0.750
Apr 0.024 0.029 0.830
Feb 0.011 0.017 0.650
LC 2A1 Mar 0.035 0.073 0.480
Apr 0.005 0.009 0.560
Tail reach
Feb 0.008 0.011 0.730
LC 2A2 Mar 0.012 0.016 0.750
Apr 0.028 0.030 0.930

These findings are similar to results by [12] who reported Irrigation Project in India reported an average adequacy
average adequacy of 0.89 while evaluating the hydraulic value of 0.5 indicating inadequate delivery of irrigation
performance of Metahara large scale irrigation scheme in water. [30] qualitatively reported inadequate irrigation
Ethiopia. [28] obtained decreasing values of the spatial water deliveries at the tail end of Doho Rice Irrigation
variation of adequacy from good to poor (head to tail end) Scheme which relates the adequacy values obtained at the
owing to water losses along the canals. [29] while tail end.
evaluating the water delivery system of Jayakwadi

Table 3.Average Adequacy of Water distribution in the system

Head Middle Tail
Spatial
Month LC-1A1 LC-1A2 LC-4A LC-4B LC-2A1 LC-2A2
PA
Feb 1.00 1.00 0.94 0.80 0.65 0.73 0.85
Mar 1.00 1.00 0.72 0.75 0.48 0.75 0.78
Apr 1.00 1.00 1.00 0.83 0.56 0.93 0.89
Temporal 1.00 1.00 0.89 0.79 0.56 0.80
Average PA 1.00 0.84 0.68 0.84

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system for delivery of water on time. Table 4 shows the

1.00 calculated value of Temporal Coefficient of Variation
0.80 (CVT ) which is the ratio of QD / QR over time T for the
canals.
0.60 The average dependability (temporal coefficient of
PA

variation values of the head, middle and tail end of DRIS

0.40
range from 0.09 to 0.12 with average dependability of
0.20 0.07. The dependability indicator is measured against a
standard by [22] presented in Table 1 where 0.00-0.10 is
0.00 classified as good, 0.11-0.20 as fair and > 0.20 classified
as poor. The average dependability of the head end canals
LC-1A1 and LC-1A2 is 0.00 which represents a reliable
Lateral Canal delivery of water. This means that farmers got water at the
required time to meet the crop water requirements. The
Figure 3.Temporal Variation of adequacy coefficient of variation at the tail end of DRIS is 0.12
which means that water delivery is fairly reliable. This
further suggests that the water delivery plan formulated
1.00 by the Doho Rice Irrigation Scheme management was
followed irrespective of the inadequate flows. [31] while
0.80 evaluating the water allocation and delivery performance
of Jiamakou Irrigation Scheme that grows apples and
0.60 cotton under surface irrigation reported a CVT of 0.23
PA

indicating poor dependability for the entire scheme. This

0.40 was attributed to the unscientific water allocation
methods employed at the scheme. In evaluating the
0.20 hydraulic performance of Hare Community managed
irrigation scheme in Ethiopia, Tebebal, [32] found that the
0.00 dependability indicator at the headend was good with a
Feb Mar Apr CVT of 0.00 while at the tail end it was poor with a CVT
Month greater than 0.2. [33] reported a CVT of 0.13 at Menemen
Figure 4. Spatial variation of Adequacy left bank irrigation district in Turkey indicating fair
dependability.
4.1.2 Dependability
Dependability or reliability expresses the consistency of a

Table 4. Dependability of water supplied in the system

Head Middle Tail
Month LC-1A1 LC-1A2 LC-4A LC-4B LC-2A1 LC-2A2
Feb 1.00 1.00 0.94 0.80 0.65 0.73
Mar 1.00 1.00 0.72 0.75 0.48 0.75
Apr 1.00 1.00 1.00 0.83 0.56 0.93
Average 1.00 1.00 0.89 0.79 0.56 0.80
Standard dev 0.00 0.00 0.12 0.03 0.07 0.09
CVT,(PD) 0.00 0.00 0.13 0.04 0.12 0.11
Average 0.00 0.09 0.12

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4.1.3 Equity that head-end farmers receive more water than tail-end
Equity is another important parameter for evaluating farmers. Water to the tail end blocks undergoes seepage
water hydraulic performance from an equitable losses owing to the fact that the canal lining material is
distribution perspective. This indicator measures the earth.
spatial coefficient of variation given as CVR. Table 5 The same results were obtained by [34] while
shows the spatial coefficient of variation calculated for comparing two management scenarios in Doho Rice
lateral canals located at head, middle and tail end sections Irrigation Scheme and Lwoba Scheme. In addition, [28]
of the Doho Rice Irrigation Scheme. found good values of equity at the head end that reduces
The equity indicator is measured against a standard by to change to fair towards the tail end. While evaluating
[22] presented in Table 1 where 0.00-0.10 is classified as the water delivery performance of smallholder irrigation
good, 0.11-0.25 as fair and > 0.25 classified as poor. At schemes in Ethiopia, [35] found CVR values greater than
the head end of the scheme, the CVR value obtained is 0.6 which indicated inequalities in water allocation. The
0.00 between February to April indicating good equity, authors attributed this inequality to poor water allocation
and at the middle-end of the scheme, the CVR is 0.09 methods and water conveyance losses along the earth
indicating good equity while at the tail end a CVR of 0.26 canals.
was obtaining which indicates poor equity. This suggests

Table 5. Equity of water supplied in the system

Head Middle Tail

Month LC-1A1 LC-1A2 CVR LC-4A LC-4B CVR LC-2A1 LC-2A2 CVR
Feb 1.00 1.00 0.00 0.94 0.80 0.11 0.65 0.73 0.08
Mar 1.00 1.00 0.00 0.72 0.75 0.02 0.48 0.75 0.32
Apr 1.00 1.00 0.00 1.00 0.83 0.13 0.56 0.93 0.36
Average 0.00 0.09 0.26
CVR

4.1.4 Equity Ratio for Head and Tail paddy fields located downstream of quaternary canals in
Doho Rice Irrigation Scheme were not satisfied with
Equity Ratio for Head and Tail (ERHT) was calculated water supply. It is reported that the water distribution
using (6). It estimates how water was managed and system along each strip is not working well and head end
delivered fairly in head and tail reach of the main canal. farmers got more water than tail end farmers. This shows
Table 6 shows the equity ratio for head and tail. The value that equitable water delivery was not achieved at the
of ERHT ranges from 2.11 to 3.76 which is a poor tertiary level.
indicator. [34] also found out that farmers cultivating

Table 6.Equity ratio for Head and Tail

Head Tail
Month LC-1A1 LC-1A2 LC-2A1 LC-2A2 ERHT
Feb 1.67 3.50 0.65 0.73 3.76
Mar 2.33 2.00 0.48 0.75 3.52
Apr 1.79 1.36 0.56 0.93 2.11
Average
3.13
ERHT

4.1.5 Efficiency sampled offtake locations and Laterals at Doho Rice

The efficiency indicator was assessed for each of the Irrigation Scheme. The tabulated results of the temporal

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value of efficiency for each outlet point at the head, which means in some areas of the Jiamakou Irrigation
middle and tail end laterals are presented in Table 7. The Scheme, more water was supplied than was required.
temporal PF value at the head end, middle and tail end of While evaluating the water delivery performance of
DRIS were found to be 0.52, 0.86 and 1.00 respectively. secondary canals in Pakistan, [37] also observed
With a value of 0.53 at lateral canal-1A1, and 0.51 at oversupply and undersupply of irrigation water to head
Lateral canal-1A2, the efficiency at the head end was end and tail end respectively. This resulted in average
categorized as poor which means excess water was efficiency of 89% with consistent overflows at the head
supplied at the head end than what was required. At the end while the tail-end suffers from minimum flows.
tail end, the water supplied for irrigation was efficiently
used by paddy for crop development. The off taking 4.1.6 Conveyance Efficiency
efficiency indicators mean that the excess water in the The conveyance efficiency (EC) was determined for the
lateral canal is lost due to seepage and evaporation [12]. Doho main canal between the intake point and Kapisa
However, the overall scheme efficiency is found to be 79 control gates where the rice blocks start. Conveyance
% which is a fair indicator based on the evaluation criteria efficiency was calculated as shown in (7). The results of
presented in Table 1. These results show that at the times the conveyance are presented in Table 8.
when the requirement for irrigation water was high, The conveyance efficiency of the 3.5km Doho main
irrigation water was used more efficiently by the farmers. canal is 68%. The canal losses 32% of the water through
The results of the efficiency indicator are consistent with seepage owing to the fact that it is an earthen canal.
what [36] obtained while evaluating the water delivery Siltation and vegetation growth within the canal interferes
and irrigation performances at field level of the Menemen with water flow reducing the conveyance efficiency.
left bank irrigation district in Turkey that mainly grows According to the FAO guidelines, the indicative
cotton and cereals. However, the water delivery of the conveyance efficiency of adequately maintained earth
scheme is somewhat organized compared to that of Doho canals with loam soils should be 70% [38]. This means
rice scheme. In both schemes, the water delivered to the that the maintenance at Doho main canal is not adequate
farmers is unknown as there are no measuring devices. enough and hence there is a need for routine maintenance.
[31] reported an average efficiency indicator of 68%

Table 7. Efficiency Indicator

Head Middle Tail
LC- LC- LC- LC- Spatial
Month LC-4A LC-4B
1A1 1A2 2A1 2A2 PF
Feb 0.60 0.29 1.00 1.00 1.00 1.00 0.81
Mar 0.43 0.50 1.00 1.00 1.00 1.00 0.82
Apr 0.56 0.74 0.16 1.00 1.00 1.00 0.74
Temporal
0.53 0.51 0.72 1.00 1.00 1.00
PF
Average
0.52 0.86 1.00 0.79
PF

Table 8. Conveyance Efficiency of Doho main canal

Location Parameter Feb Mar Apr Ec

Headworks Vm(m3/s) 1.38 1.33 1.56

Kapisa gates Q0(m3/s) 0.92 0.95 1.02

67% 71% 65% 68%

4.1.7 Delivery Performance Ratio The value of delivery performance ratio, DPR at the main,

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 E. Bwambale et al. Hydraulic performance evaluation of the water conveyance system

southern and northern canals of Doho Rice Irrigation and the crop water requirements for rice for the three-
Scheme ranges from 0.45 to 1.05 as presented in Table 9. month period of February, March and April 2019.
In the main Canal, DPR is low due to fluctuation in the The average water delivery performance to the lateral
quantity of water abstracted at the intake since it varies canals within the scheme is fair in terms of adequacy
with water availability in River Manafwa. Another reason 0.84(fair), dependability 0.07(good), equity 0.26 (poor),
is the reduction in volume as a result of siltation and and efficiency indicator 0.79(fair). However, the Equity
deposition of planktons and water weeds along the canal. ratio of head and tail shows that there are inequalities in
This reduces the canal carrying capacity leading to a low water distribution. The conveyance efficiency in the main
delivery performance ratio. The DPR in the southern canal was found to be 68 %. It is important to make certain
canal in March is 1.05 meaning more water was diverted management structural changes in order to improve
to the southern canal at the Kapisa gates in March. The performance at the tail end. In this regard, greater
overall DPR of the conveyance system was 0.78 importance must be placed on repair and maintenance
work so as to reduce water losses during conveyance.
There is need to modernize the irrigation scheme to
5. Conclusion
improve irrigation efficiency, water delivery services to
In this study, an evaluation was made of the water all users, and enhance resource utilization including cost-
delivery performance on the main and lateral canals. At effectiveness of operation and management. Water
the main canal, the water conveyance efficiency allocation plans and schedules need to be drafted and
parameter was used while at the lateral canals the strictly adhered to promote equity of water distribution
indicators of adequacy, dependability, equity, and among the irrigation blocks.
efficiency were used. These indicators were calculated
from the amounts of irrigation water which was supplied

Table 9.Delivery Performance Ratio

Canal Month Qact Qdes DPR Average
Feb 1.38 3.6 0.38
Main Mar 1.330 3.600 0.37 0.45
Apr 2.100 3.600 0.58
Feb 0.540 0.700 0.77
Southern
Mar 0.680 0.700 0.97 1.05
canal
Apr 0.980 0.700 1.40
Feb 0.480 0.500 0.96
Northern
Mar 0.212 0.500 0.42 0.86
canal
Apr 0.600 0.500 1.20
0.78

Acknowledgments
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