COMMISION.INTERNATIONALE
DES.GRANDS.BARRAGES
VINGT.TROISIEME CONGRES
DES.GRADS.BARRAGES
Brasilia. MAY 2009.
ANALYSYS OF THE PERFORMANCE OF INTAKE AND CHECK
STRUCTURES IN QAZVIN, IRAN IRRIGATION PROJECT AND
PROVIDING ALTERNATIVE METHODES
Saeed Kazemi Mohsen Abadi
PH.D. Student, Islamic Azad University of Khuzestan, Iran, Saeed_Kazemi_ma@yahoo.com
Amin Zaker Fathi
Supervising Engineer in Mahab Ghods Company, Iran, A_Zakerfathi@yahoo.com
1.
INTRODUCTION
Construction of different water structures for suitable water conveyance and
distribution for agricultural use is often costly and the increases the final cost
allocated water for the irrigation of agricultural fields. In addition, the low level at the
total irrigation efficiency generally stems from ineffective operation management and
seepage losses in the conveyance and distribution network and the irrigation losses
in the field. This causes remarkable increase in the dimensions and physical sizes of
hydraulic structure used in the network and considerable increase in the allocated
discharge of water resources. Management for optimization of water distribution and
consumption in the networks plays an effective role in the improvement of irrigation
efficiency. Therefore it is necessary for hydraulic structures to be selected method,
designed and constructed and operated in a way to optimize the efficiency and
perform an effective water conveyance in to the fields.
1
2.
STUDIES ACOMMPISHED BY OTHERS
In spite of presenting different criteria collection by irrigation network designers
to select and design the control structures and impoundment in each country of the
world, but there are limited information and procedure reports of these structures in
actual situation, applied design criteria and also procedure of modification and
reconstruction them.
United Nation Office of Technical Cooperation (1973) has done researches in
the field of intakes procedure, on the basis of the results, it was specified that
suspended material in water and their combination, changing and vacillating the
water level in water supply reservoir and expected accuracy degree of sensitivity of
intakes are effective for choosing intake types.
Ghamarnia (1992) after research on several irrigation network of Iran
concerning the selection method of intake structures suggested that “due to the lack
of reliable power resources and also the changeable scales for operating of
equipment, it is recommended to use a durable system with least need for recording,
maintaining and operating skill instead of an automatic system.
By surveying Qazvin irrigation network, Bouchali Safiee (1992) found that
because of full automatic and semi automatic performance of water distribution at
network with amil gates, it will be probable with putting additional weight and other
obstacles these gates will exit in initial adjusting situation and is changed in crossing
discharge.
Razavi Nabavi (1995) at his research of investigating coefficients on Neyrpic
gates in irrigation network of Qazvin plain, presented following results:
a- It is recommended applying Neyrpic modules in under construction irrigation
networks.
b- More contributions of observed errors are related to manufacturing methods
and changing hydraulic coefficient.
c- Flow approaching situation to gates or gates located rather than sides wall
and this matter that if it’s located in middle or the sides, will effect on outlet
flow hydraulic.
d- It is recommended that in all irrigation networks which are equipped with
Neyrpic modules, before starting the operation and then every couple of
years (for some 5years) existing modules should be water proofed.
Salemi (1997), in basis of his studies regarding hydraulic performance
assessment and operation of flow control structure in irrigation networks of
2
Zayandehrood River –Esfahan and Dorodzan River-Fars province has suggested
that agricultural organizations could play an effective role than regional water
authorities in relation to operation management of irrigation networks, to improve
water distribution efficiency. Also specifying plants water requirement, cultivation
pattern and lands integration management will optimize consumption and irrigation
efficiency. As the result of this research, using of Neyrpic type module gates is
recommended because of a better control on networks, especially for regions that
farmers have the higher awareness.
Pilpayeh (2003) accomplished a comparison with nominal and measured
discharges. Results of his study are consisted of:
1) Neyrpic type module gates are established at the beginning of third grade
irrigation network in Moghan should act as free downstream and in case of
gates drawing; the excessive error spoils their efficiency.
2) Most of second grade network of Parsabad region irrigation, Neyrpic type
module gates doesn’t have required hydraulic mechanical accuracy.
3) Because of the poor reinforcement, the Neyrpic module gates always are
disturbed and rubbed by farmers and strangers.
Montazer and Kouchakzadeh (2001) have surveyed different relations of
hydraulic sensitivity for Neyrpic gates and prepared characteristic discharge_height
curves in basis of field data, for sensitivity study during the operating period. They
expressed that hydraulic sensitivity is more in these gates type at local situation than
presented typical curves. They also came to the result that between all different kind
of single mask and double mask gates in local and theoretical situation, X1 type
gates have most hydraulic sensitivity to water level changes while C1, C2 type
gates sensitivity is in the same situation 4.7 and 11.8 times less of X1 type.
Montazer and Kouchakzadeh (2001) reported that the double mask gates bed
loss is 2.7 times more than single mask. Field observations has showed difference in
gates hydraulic sensitivities related to their situations, so that the middle established
gates have more hydraulic sensitivity than sides gates established. They found that
the designed and measured discharge in mask gate aren’t same, therefore to specify
real hydraulic sensitivity of gates, it is necessary to calibrate gates after installation.
3
3.
RESEARCH METHOD
We studied the available design drawings of different components of network
for this research. In regard to investigating the performance of intake gates, we
measured discharge and depth of the water at downstream to find the sinking
condition. We measured water depth for determining head loss at upstream with
curves related to single and double baffle modules, the expected discharge of gates
was determined and was compared with measured discharge at downstream and
nominal discharge that should be crossed in gate. After that in regard to investigate
performance of control gates according to crossing flow head loss from these
structures, in suitable sections of upstream and downstream of gates in there,
current flow turbulence in flow was lower. We measured depth and water velocity
and also difference of bed levels in two sections and we calculated available head
loss in maintenance situation by energy equation and we compared them with
anticipated head loss in design stage. It is interesting that you know, derivation of
head loss that the designer had anticipated for each gate was a hard work. It must
be mentioned that in order to performance evaluation of amil and intake gates, I
chose 43 intake gates and 10 amil sluices, in this study.
4.
4.1.
DISCUTION AND CONCLUSION
Surveying the intakes gates procedure
Considering the measurements done, the measured depth on weir crest, in
most gates is more than the depth that includes the range of maximum +10 percent
discharges. After the performing surveys and the negotiations with the authorities,
experts, irrigators and the farmers of the location, we know that the increase of the
water depth in upstream intakes and the nominal depth are closely interconnected
because of reasons such as the increase of the canal roughness coefficient, the
canal side erosion due to passing of time, a lot of sediment inside the intake canal
4
and behind the intake gate, lack of adjustment of amil sluice since the construction
of the network and its initial adjustment, disturbing amil gates to obtain more water
by exploiters and others.
In spite of depth increase behind the intake gate, it was observed that in most
evaluated cases; the amount of measured discharge was less than the calculated
discharged determined by the chart. According our residential surveys and
investigations, showed that in all these gates, the flow overtopped them and this
matter decreased the passing discharge in comparison to the calculated discharge
that passed from gates. The other main reasons that we observed, in difference
between the measured discharge and the calculated discharge in module typical
Neyrpic gates, cases such as overtopping water from the intake gate, because of
disturbing amil gates to get more water, overtopping water gates due to the
increasing of water depth in gate upstream because of increase of roughness
coefficient, disturbing the intakes by farmers, leakage of water from the closed gates
behind, water escape from the sides of gate, leakage of water of from under mask.
4.1.1.
Drawing the new charts for module gates type Neyrpic, used by Qazvin
irrigation network, Iran.
After measuring by establishing relation between depth and the calculation
discharge of the evaluated gates, for the gates XX 1 , XX 2 , L1 , C1 , we drew new
charts and point out some of them below (Figure 1 to 9). In addition, expected
discharge is between Q1 and Q2 .
In these figures, Q1 is measurement discharge plus 10 percent instrument error, Q2
is measurement discharge minus 10 percent instrument error, Qn is nominal
discharge, H m is measured depth on the weir and H n is nominal depth on the weir.
5
1.20
Q1
Q2
Poly. (Q1)
Poly. (Q2)
1.15
1.10
Q1/Qn & Q2/Qn
1.05
1.00
0.95
0.90
0.85
0.80
0.75
0.70
0.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
1.45
Hm / Hn
Fig.1
Free dimension graph in gates type of XX 1 and depth on the weir
between 26 to 37.5 (Centimeter)
1.25
1.20
1.15
Q1/Qn & Q2/Qn
1.10
1.05
1.00
0.95
0.90
Q1
Q2
Poly. (Q1)
Poly. (Q2)
0.85
0.80
0.75
1.40
1.45
1.50
1.55
1.60
1.65
1.70
Hm / Hn
Fig.2
Free dimension graph in gates type of XX 1 and depth on the weir
between 38 to 45 (Centimeter)
6
1.4
1.3
Q1/Qn & Q2/Qn
1.2
1.1
1.0
Q1
Q2
Poly. (Q1)
Poly. (Q2)
0.9
0.8
1.65
1.70
1.75
1.80
1.85
1.90
1.95
Hm / Hn
Fig.3
Free dimension graph in gates type of XX 1 and depth on the weir
between 45.5 to 51.5 (Centimeter)
1.5
Q1
Q2
Poly. (Q1)
Poly. (Q2)
1.4
1.3
Q1 / Qn & Q2 / Qn
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.9
1.0
1.1
1.2
1.3
1.4
1.5
Hm / Hn
Fig.4
Free dimension graph in gates type of XX 2
7
1.6
1.7
1.20
1.15
Q1/Qn&Q2/Qn
1.10
1.05
1.00
Q1
Q2
Poly. (Q1)
Poly. (Q2)
0.95
0.90
1.08
1.10
1.12
1.14
1.16
1.18
1.20
1.22
1.24
1.26
1.28
Hm / Hn
Fig.5
Free dimension graph in gates type of L1 and depth on the weir
between 54.5 to 63 (Centimeter)
1.5
1.4
Q1/Qn&Q2/Qn
1.3
1.2
1.1
1.0
Q1
Q2
Poly. (Q1)
Poly. (Q2)
0.9
0.8
1.25
1.30
1.35
1.40
1.45
1.50
1.55
1.60
Hm / Hn
Fig.6
Free dimension graph in gates type of L1 and depth on the weir
between 64 to 80 (Centimeter)
8
1.65
1.3
1.2
Q1/Qn&Q2/Qn
1.1
1.0
Q1
Q2
Poly. (Q1)
Poly. (Q2)
0.9
0.8
0.7
1.30
1.32
1.34
1.36
1.38
1.40
1.42
1.44
1.46
1.48
1.50
Hm / Hn
Fig.7
Free dimension graph in gates type of C1
1.40
1.30
Q1/Qn & Q2/Qn
1.20
1.10
1.00
0.90
0.80
0.70
0.95
1.05
1.15
1.25
1.35
1.45
1.55
1.65
1.75
Hm / Hn
Poly. (Q1&26<Hm<37.5)
Poly. (Q2&26<Hm<37.5)
Poly. (Q1&38<Hm<45)
Poly. (Q2&38<Hm<45)
Poly. (Q1&45.5<Hm<51.5)
Poly. (Q2&45.5<Hm<51.5)
Fig.8
Free dimension general graph in gates type of XX 1
9
1.85
1.95
1.50
1.40
Q1/Qn & Q2/Qn
1.30
1.20
1.10
1.00
0.90
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
1.45
1.50
1.55
1.60
1.65
Hm/Hn
Poly. (Q1&54.5<Hm<63)
Poly. (Q2&54.5<Hm<63)
Poly. (Q1&64<Hm<80)
Poly. (Q2&64<Hm<80)
Fig.9
Free dimension general graph in gates type of L1
4.1.2.
Calculation of new relations for module gates Neyrpic type to be used in
irrigation network of Qazvin, Iran.
After drawing the above charts, we found that it was better to derivate
relations from the mentioned chart that makes use of them simpler. Relations those
to be suggested for use of module gates Neyrpic type in the irrigation network of
Qazvin plain are as table1.
10
Table 1
Suggestive relations for Neyrpic type module gates
Type
module
Range of height
changes
Free dimension formula of depth over the module spillway
and passing discharge
2
H
q1
 8.0749 m
qn
 Hn

H
  19.229 m

 Hn
H
q2
 7.8992 m
qn
 Hn

H
  18.81 m

 Hn
R2

  10.276

0.974

  10.052

0.974

  36.358

0.875

  35.567

0.875

  7.8491

0.957

  7.6783

0.957
26  H m  37.5
XX 1
38  H m  45
45.5  H m  51.5
XX 2
27  H m  46
2
2
H
q1
 15.586 m
qn
 Hn

H
  47.059 m

 Hn
H
q2
 15.246 m
qn
 Hn

H
  46.035 m

 Hn
2
2
H
q1
 1.5138 m
qn
 Hn

H
  7.7116 m

 Hn
H
q2
 1.4809 m
qn
 Hn

H
  7.5438 m

 Hn
2
3
H
q1
 8.3233 m
qn
 Hn

H
  38.096 m

 Hn
H
q2
 8.1422 m
qn
 Hn

H
  37.267 m

 Hn
3
11
2

H
  56.605 m

 Hn
2

H
  55.374 m

 Hn

  28.08

0.907

  27.469

0.907
Continuation of Table 1
Type
module
Range of height
changes
Free dimension formula of depth over the module
spillway and passing discharge
2
H
q1
 16.248 m
qn
 Hn

H
  37.732 m

 Hn
H
q2
 15.894 m
qn
 Hn

H
  36.911 m

 Hn
H
q1
 8.137 m
qn
 Hn

H
  24.301 m

 Hn
H
q2
 7.9599 m
qn
 Hn

H
  23.772 m

 Hn
H
q1
 62.978 m
qn
 Hn

H
  175.32 m

 Hn
H
q2
 61.607 m
qn
 Hn

H
  171.51 m

 Hn
R2

  22.874

0.847

  22.376

0.847

  16.771

0.962

  16.406

0.962

  122.75

1

  120.08

1
54.5  H m  63
2
L1
64  H m  80
C1
99  H m  117
4.2.
2
2
2
2
AMIL GATES
According table 2, it’s considered in all cases passing discharge is lower than
designed discharge amount. This matter has originated from channel discharge
decrease, because of water requirement decline. Nominal loss and design loss
amounts in fifth and sixth column related to loss of passing and designing
12
discharges on basis of presented graph by manufacturer companies of these
gates types. Although loss amounts in last column have been done on basis of
local test measurements (Formula 1 to 3).
v12
v2
 y 2  2  z  h f
2g
2g
1


v2  
v2
h f   y1  1    y 2  2  z 
2g  
2g


2
h f  E1  E 2  z 
3
y1 
Which in the above equations, y1 = depth of water in the upstream gate,
y 2 = depth of water in the downstream gate, v1 = velocity in the upstream gate,
v2 = velocity in the downstream gate, z =difference of upstream and
downstream for bed height, E1 = Specific energy for upstream, E2 = Specific
energy for downstream.
Table 2 shows that loss amounts of amil gates in exploiting situation are more
than nominal amounts. It has been specified that sediments, lack of proper
adjustment and disturbing them by farmers due to that subject. It is observed that
measured loss is lower than designed loss in some gates and this reason is
related to lower discharge than designing discharge. So regarding above
subjects, it is predicted that load loss of passing discharge from under the gate
increase. This act increases the water level depth in upstream of gate and raise
of passing discharge from intake gates.
13
Table2
Amounts of measured loss the amil gates and other specification in irrigation
network of Qazvin plain.
Gate Name
Gate
type
Designing
Discharge
Passing
Discharge
Nominal
loss
Designing
loss
Measured
loss
(cms)
(LPS)
(cm)
(cm)
(cm)
L32-S2-CH
D180
1.05
515
10
8
18.7
L3-S5
D315
3.00
1072
9
22
36.9
L3-S6
D315
2.80
756
8
34
24.6
L3-S'2-CH
D280
1.74
567
5
10
25.8
L4A-S4-CH
D180
0.70
586
4
10
16.5
L6-S3
D315
2.40
1538
5
11
10.6
L6-S4-CH
D280
2.30
1181
9
10
24.2
L6-S5
D280
2.30
786
9
16
14.4
L6-S'5
D220
1.34
352
8
15
11.1
L7-S2-CH
D315
2.50
1278
7
12
16.4
14
5.
1.
RESULT OF THIS RESEARCH
Water overtopping from the gate (due to lack of adjustment amil gates or
disturbing them by farmers) causes increases discharge delivery to farmers
in some gates and decreases the rest of discharge in canal for downstream
intakes.
2. Oldness and erosion of gates, especially xx1 type gates made the inefficient
and some of them must be replaced. Gate oldness lets water to leak from
closed gates sill and increases the delivered discharge.
3. Water passing through the gates mask causes that passing discharge under
the gate, be more than the nominal discharge or delivered discharge.
4. Over drown in downstream of some intakes that acts a wall prevent the water
flow, has decreased the passing discharge through them.
5. As it was expected, the single mask gates are more sensitive than double
mask gates.
6. The lack of amils adjustment makes water overtop intake gate and also water
passing the sides of the gate.
7. Sediment behind the intake and amil gates decreases the coarseness
coefficient of flow and this has decreased passing discharge in some gates.
8. Being a lot of sediment in intake canal makes many problems.
9. During the time and regarding the canal erosion, their roughness coefficient
increases, and it adds the depth of water behind the intake gates, therefore
increases the water discharge for non-submerged gates.
10. Neyrpic type modules with operating as weir; are too sensitive to change of
upstream head. Therefore should create a condition to convert the gates from
a weir to an opening. This condition will be created, if amil adjustment and
dredge of intake canal is done properly.
15
6.
SUGESSTIONS
1- By adjusting the amil gates, water is distributed accurately. Adjustment is
better to be done in the full water and low water for canals.
2- By training the farmers and adequate supervision by the M&O Company
for the irrigation network, most of the problems can be solved.
3- It seems more supervision on water selling is required. Because some
farmers believed that a certain amount of water was sold to several
persons.
4- Using new lands for water farming and increasing water demand have
made farmers to break canals. To avoid facing to this event, it is
necessary to construct new gates.
5- Removing the rust, painting and repairing the gates in most intake-gates
and especially intake type xx1 will have a positive effect in their procedure.
6- Amil gates lack of adjustment and unsuitable maintenance of them, make
efficiency lower and drop increasing than nominal position of gates.
7- Sediments behind the gates and amil gates decrease the coarseness
coefficient of flow and therefore decrease discharge rate through them.
8- After adjusting the amils we should insert a clear sign of adjusted depth
behind the gate, so that in case of the gate change, we can adjust the gate
easier.
9- Repairing the destroyed points of the canal networks, and dredge of
canals sediment lead to increasing the efficiency of distribution and
conveyance.
10- Exact studies on culture, traditions, customs, the way of irrigation and the
regions that we consider to construct network have paramount
importance. Because the mode of exploiting the network is very important.
It is advised without a suitable situation of maintenance and exploitation
instead of Amil automatic adjustment structures, to use the radial gates
types. Because we can have control on this structures. Also we can use
the kinds of stable spillways in different situations.
11- We suggest establishing a centre to improve the accuracy for test of gates
that are constructed domestically and the hydraulic tests on these gates
before setting to calibration.
16
References
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SUMMARY
The shortage of rainfall, non–uniform distribution and, generally, the deficiency
of water resources in Iran, dictates the optimal of water resources. In this regard,
irrigation networks are constructed to provide an effective use of water conveyance
and distribution. However, due to the lack of suitable use and maintenance, the
mean irrigation efficiency in irrigation network in Iran in about 30 – 35 percent. For
this purpose recognition of effective factors in low irrigation efficiency, performance
of check structures and turnout gates in Qazvin irrigation network were evaluated.
In this study, turnout and check gates use were considered in both viewpoints,
hydraulically and operation and maintenance conditions. Hydraulic assessment
includes discharge and head loss. In this research, function of 42 Neyrpic – turnout
gates and 10 amil automated check gates were evaluated.
It is clear that impoundment of canals were confronted many difficulties by
reason of turnout and check gates touches by operators, lack of proper management
for amil adjustment and sediments empty in canals, so that, some turnout gates
have discharge more than nominal and computational discharge, that cause to water
shortage in final gates. It is observed that some turnout gates delivery water to
downstream canals less than nominal and computational discharge by reason of
gates submergence and retouching. Lack of suitable services by network
supervisors and accumulation of sediment and rubbish in back of check gates cause
to produce head loss more than nominal head loss in water way. The results showed
that better management for Qazvin irrigation network. Also the results indicated that
Neyrpic–modules gates will have satisfied accuracy of water delivery if check
structures is controlled, although it is necessary to create proper instruction for
control of home-made turnout gates.
Finally, radial gates, slide gates and or fixed weirs are used for water level
adjustment is recommended if irrigation network operation is not good.
Key Words: irrigation, Neyrpic, amil, sediment, checks gates.
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