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DETERMINING THE EFFICIENCY COEFFICIENT OF THE NEW
DARGOM CANAL THROUGH FIELD MEASUREMENTS
Jurayev Bakhrom Bakhriddinovich
Head of Laboratory (PhD) at the Samarkand Regional Center of the Scientific
Research Institute of Irrigation and Water Problems
Turayev Shamshiddin Jurakulovich
Director of the Samarkand Regional Center of the Scientific Research Institute of
Irrigation and Water Problems. independent researcher
https://doi.org/10.5281/zenodo.16779034
Abstract
In this article, the efficiency coefficient of the Yangi Dargom Canal, which
draws water from the left tributary of the Zarafshan River, was determined using
generally accepted hydraulic laws and the hydrometric method. The water
discharge of the branches receiving water from the canal was calculated and the
results were compared.
The main purpose of measuring water consumption is to achieve efficient
water use in response to climate change in our region and the reduction of water
resources in sources due to anthropogenic factors. This is accomplished through
knowing water flow rates, which enables the development of water balance
programs along major rivers, canals, and internal networks during low-water
years.
Keywords:
Water discharge, flow velocity, canal, gauging station, branch.
Introduction.
Comprehensive measures have been implemented in the
agriculture sector of our republic aimed at conserving water resources, ensuring
their rational and efficient use, including maintaining reliable operation of
irrigation systems, and significant results have been achieved. The Dargom Canal
provides water to 67.5 thousand hectares of land in Samarkand region and 50
thousand hectares in Kashkadarya region. The annual flow volume amounts to
0.9-1.2 km3. The functioning of 562 km of inter-farm and intra-farm canals and
412 hydraulic structures in the Dargom irrigation system depends on the
technical condition of the Dargom Canal.
In recent years, intense erosion processes occurring in the canal bed have
resulted in the collapse of canal banks, siltation of the channel, and consequently,
a decrease in water carrying capacity, leading to a decline in the canal's efficiency.
The primary cause of this is the high flow velocity due to the canal's steep
longitudinal slope (average slope of 0.004). Instances have been observed where
the progression of these channel processes has had negative impacts, potentially
leading to emergency situations. However, the high kinetic energy of the flow also
presents an opportunity for positive utilization of this condition.
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Research subject:
Water for the Yangi and Aylanma Dargom canals is
drawn from the left-bank tributary of the Ravotkhoja hydroelectric complex built
on the Zarafshan River. The Yangi Dargom canal is 10.2 km long and is fully lined
with concrete. The canal is equipped with 10 water intake branches and a
hydrological station.
Figure 1. The river water intake section of the canal
The climate of the canal area is highly variable, characterized by relatively
dry, hot summers and cold winters. Annual precipitation amounts to 329 mm. The
air in the region is dry with high evaporation rates (1135 mm). During summer,
the absolute maximum air temperature reaches +38-40°C, while in winter, the
minimum temperature drops to -26-30°C, with an average annual temperature of
+12°C. The period of highest precipitation occurs from October to March,
accounting for more than 75% of the annual amount. The area predominantly
experiences winds from the northeast and north directions.
The technical condition of the structures.
All structures in the Dargom
Canal are inspected after the vegetation period, during the autumn and spring
seasons. The following observations are conducted to assess the condition of
structures and equipment in the canal: water levels in the upper and lower
reaches of structures, silt accumulation along the canal route in the upper reaches
and erosion of the bottom and banks in the lower reaches, the impact of water
flow on the condition of structures, monitoring of areas prone to damage and
potential accidents, and filtration from structures and the canal. During the
monitoring process, malfunctions in the structures are identified and measures to
eliminate them are determined.
Observations are conducted using visual or geodetic methods and other
equipment. After a distance of 11 km from the main structure of New Dargom, the
canals in this zone merge and flow into Old Dargom. The length is 10.5 km, with a
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water discharge of 125 m3/s, and a total elevation drop of 55 m along its slope.
There is a 600-meter tunnel along the canal route. The water energy generated
from the steep slope is dissipated by 1 rapid-flow spillway and 13 stepped
spillways (cascades).
Натижалар ва мулоҳаза:
Currently, the determination of the efficiency
coefficient along the sections and length of the Yangi Dargom Canal is carried out
primarily using the hydrometric method. In this method, a specific section of the
canal is selected to determine its efficiency. Within the chosen section, the
locations of the upper and lower cross-sections are identified, and the water
discharge is measured using hydrometric instruments. The length of the selected
section (segment) is determined by the following formula:
L=67,4Pi
/
𝜎√𝑛𝑃
(1.1)
Here, L represents the length of the selected section in km; P_i denotes the
accuracy of water flow measurements in %; P indicates the accuracy of
determining water loss in %; σ represents the water loss per 1 km of canal length
(expressed as a percentage of water flow); and n is the number of measurements.
After measuring the water discharge in the upper reach, the water
discharges of the water intake and canal outlets in the lower reach are measured.
The time it takes for water to travel from the upper cross-section to the lower
cross-section is determined using the following formula:
T=L/60 V
av
(1.2)
The water loss between the selected sections is determined by the following
formula:
S=Q
.hh
-
∑ 𝑄
𝑔𝑎
+
∑ 𝑄
𝑤𝑑
– Q
low
(1.3)
where: S - value of water loss in the selected section, m
3
/s; Q
yuqor
and Q
past
-
water discharges measured in the upper and lower reaches, m
3
/s; ∑Q
ar
- the sum
of water discharges of all water intake ditches between the sections, m
3
/s;
∑Q_tash - the sum of water discharges discharged into the canal between sections,
m
3
/s.
After determining the absolute value of water loss in the selected section,
the relative losses for each kilometer of length are calculated using the following
formula:
S1=1000S/L
l/s 1 км
(1.4)
The percentage of water loss per 1 km of length, relative to the average
water discharge of the measured cross-sections, is determined using the
following formula.
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𝜎
= 100
𝑆
𝑙
/𝑄
𝑤𝑑
(1.5)
here,
Q
wd
=(Q
ga
+Q
low
)/2
The coefficient of efficiency (COE) for the canal section is determined by the
following formula:
FIK = (
Q
hh
–S)/
Q
hh
(1.6)
At the head of the Yangi Dargom canal, the water flow measurement result
was Q=59.25 m
3
/s, the cross-sectional area in the profile was 35.34 m
2
, the
average flow velocity was 1.68 m/s, the maximum velocity was 2.77 m/s, and the
width of the water surface measured 18.5 m (Figure 2).
Figure 2. Measurement results at the Yangi Dargom main hydropost
The water discharge measurement in the lower reach of the Yangi Dargom
Canal yielded the following results: flow rate Q=53.10 m
3
/s, cross-sectional area
of the profile 22.62 m
2
, average flow velocity 2.35 m/s, maximum velocity 3.69
m/s, and water surface width 12.8 m (Figure 3).
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Figure 3. Measurement results at the hydropost of the lower reach of
Yangi Dargom
Water flow measurements were conducted in the branches drawing water
from the Yangi Dargom Canal, which falls under the management of the Zarafshan
Main System Operation Department. The results obtained are presented in the
first table.
The efficiency coefficient of the Yangi Dargom Canal was determined using
the hydrometric method based on field measurements over a length of 10.6 km.
In this process, an accurate calculation of water discharge in the canal's water
intake network was conducted, resulting in the determination of the canal's
efficiency coefficient to be 0.92 (Table 1). It was found that while the canal's
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efficiency coefficient was previously considered to be 0.99, water losses have
been increasing due to the deterioration of the canal's concrete lining (Figure 4).
Table 1. Water flow calculations for branches drawing water from the
Yangi Darg'om Canal of the Zarafshon Main System Operation Department
№
Name of
hydropost or
network
Installed
PC
Length of
water
intake
network,
km
13.08.2024
annual
water flow
rate
Border
water flow
measuring
station
The Head of
New Darg'om
59.253
1
Elpak-1
0.10
0.05
2 Rakhmatabad
0.10
0.08
3
New ditch
0.50
0.30
4
Elpak 3
0.10
0.05
5
Boiler ditch
1.00
0.25
6 Irrigation ditch
0.15
0.05
7
Kid
0.50
0.10
8
Kid 1
0.30
0.01
9
Naked
1.00
0.085
10
Bogzagan
5.00
0.60
Total networks
1.57
New Dargom
Gulba
Hydroelectric
Power Station
Gauging
Station
53.100
FIK
0.923
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Figure 4. Utilization of Water from the Dargom Canal
Conclusion
Hydrometric, morphological, and kinematic characteristics of the Yangi
Darg'om Canal were determined based on field measurements, and methods for
calculating the canal's efficiency coefficient were presented. Water discharge,
flow velocity, canal surface width, and other characteristics were obtained using
modern measuring instruments. The technical condition of structures and water
intake facilities located along the route of the Yangi Darg'om Canal was studied. It
was found that the canal's efficiency has decreased as a result of the deterioration
of its concrete lining.
By increasing the efficiency of canals, it is possible to improve water supply
for agricultural crops and automate water management processes at water
management facilities. This allows for transparent water accounting. Due to
global climate change, population growth, economic sector expansion, and the
increasing annual demand for water, it is necessary to address the issues of timely
delivery of water limits to consumers and mitigation of water demand. This can
be achieved by utilizing modern advanced technologies in water metering
systems to alleviate the year-on-year water resource scarcity.
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
1
3
5
7
9
11 13 15 17 19 21 23 25 27 29 31
Q, м
3
/s
kun
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