use of numerical modelling for management of canal irrigation water

USE OF NUMERICAL MODELLING FOR MANAGEMENT OF CANALIRRIGATION WATERy

ABDUL RAZZAQ GHUMMAN,1* MUHAMMAD ZUBAIR KHAN2

AND MUHAMMAD JAMAL KHAN2

1Faculty of Civil Engineering, University of Engineering and Technology, Taxila, Pakistan2Department of Water Management, NWFP Agricultural University Peshawar, Pakistan

ABSTRACT

Flow regulation and distribution structures play an important role in the overall management of irrigation

canals. In this paper the solution of one-dimensional Saint Venant equations of continuity and momentum was

applied to a secondary canal in the Abazai Branch of the Upper Swat Canal Irrigation System, North West

Frontier Province of Pakistan. The system has been changed from supply based to crop based. The aim of the

study was to firstly evaluate the performance of canal outlets under different discharge conditions. The second

aim was to assess the response of any modifications in the dimensions of the canal outlets on water distribution

under different discharges. Five cases of 100, 80, 70 and 50% of design discharge were tested. The additional

operational option of opening and closure of the canal was also evaluated. It was found that under the existing

configuration of the canal, the majority of the canal outlets were not drawing discharges according to their

allocations for all the four discharge levels. Modifications in outlet dimensions improved the outlet

performance. The best performance of canal outlets was obtained under 100 and 80% of the design canal

discharge after modifications. In the periods of low irrigation demand, the study recommends opening and

closure of the canal instead of operation at lower than 80% of design discharge. Copyright # 2006 John Wiley

& Sons, Ltd.

key words: canal performance; irrigation management; models, outlets; water distribution

Received 28 October 2005; Revised 25 February 2006; Accepted 10 April 2006

RESUME

Les ouvrages de controle et de repartition des debits jouent un role important dans la gestion d’ensemble des

canaux d’irrigation. Dans cet article la resolution d’equations unidimensionnelles de Saint Venant de continuite

et impulsion a ete appliquee a un canal secondaire de la branche Abazai du Upper Swat Canal System dans le

Nord-Ouest du Pakistan. La gestion du systeme par la ressource est passee a une gestion par la demande (des

cultures). Le but de l’etude etait d’abord d’evaluer la performance des emissaires sous differentes conditions de

debit. Le deuxieme objectif etait d’evaluer l’effet de modifications dans les dimensions des emissaires sur la

distribution de l’eau en faisant varier le debit. Cinq cas de debit d’equipement (100%, 80%, 70% et 50%) ont ete

testes. L’option supplementaire d’ouverture et de fermeture du canal a egalement ete evaluee. Il a ete trouve que

dans la configuration existante du canal la majorite des emissaires ne transitaient pas le debit prevu pour les

quatre niveaux de debit etudies. Des modifications apportees a leurs dimensions ont ameliore leurs perform-

ances. La meilleure performance des emissaires a ete obtenue pour 100% et 80% du debit d’equipement du

canal apres modifications. Dans les periodes de moindre demande d’irrigation, l’etude recommande l’ouverture et la

IRRIGATION AND DRAINAGE

Irrig. and Drain. 55: 445–458 (2006)

Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/ird.265

*Correspondence to: A. R. Ghumman, Faculty of Civil Engineering, University of Engineering and Technology, Taxila, Pakistan.E-mail: [email protected] de modeles numeriques pour la gestion d’un canal d’irrigation.

Copyright # 2006 John Wiley & Sons, Ltd.

fermeture du canal plutot que son fonctionnement a des debits inferieurs a 80% du debit d’equipement.

Copyright # 2006 John Wiley & Sons, Ltd.

mots cles: distribution d’eau; emissaires; gestion d’irrigation; modeles; performance de canal

INTRODUCTION

The design of canals and irrigation outlets in many developing countries has remained a challenging job for

engineers and researchers. The most important design objective of a canal is the ability of the outlets along the

canal to draw their design discharges. For equitable water distribution in secondary canals of gravity irrigation

systems with very few flow control structures, the dimensions of the outlets need critical studies. These outlets

draw water from the canal in response to the water level in the canal. Performance evaluation studies for different

canals have been carried out in the past. Babar (2000), Shah (2000), Murray-Rust and Halsema (1998), Khan

et al. (2000) and Halsema (2002) found that the performance of secondary canals was generally not good as

far as equitable water distribution was concerned, due to underperformance of the design of the outlets.

Shahrokhnia and Javan (2005) applied HEC-RAS to evaluate the gate opening rules used to control the

offtakes. These rules control discharge reductions of offtakes due to discharge reductions at the system source.

These studies have, however, been restricted to the assessment of performance of the canals only. Due to limited

water regulation structures in such canals, modifications in the dimensions of the outlets offer the most feasible

option for improvement in performance. The present study aims at suggesting improvements in the design

dimensions of irrigation outlets to achieve equitable water distribution under varying irrigation demand. The

model provides a cost-effective way to assess the impact of different modifications on performance of the

canal. The canal management model CANALMAN, developed by the Utah State University, USA (Merkley,

1997) was applied to a secondary canal of the Upper Swat Canal (USC) Irrigation System in the North West

Frontier Province (NWFP) of Pakistan. The package was developed for performing hydraulic simulations

of unsteady flow in branching canal networks. The model is designed for use in design, analysis and operational

of irrigation canals.

Pakistan is a developing country and depends heavily on irrigated agriculture. With the rapid increase in the

demand for higher production per unit area in Pakistan as in many other developing countries in general and in the

NWFP in particular, there have been a number of efforts to change the basis of irrigation from supply-driven

protective systems to crop-based irrigation operations. One of the major systems in Pakistan to undergo this type of

transformation is the USC, situated in the NWFP. The system was redesigned to increase its water allowance from

3.5 to 6 mm d�1.

Assessment of the hydraulic performance of canals with crop-based water allowances, is important due to

varying irrigation demand. The crop-based canals, therefore, require to be operated at different discharges.

The aim of this study was to determine the performance of the canal at different discharges, to recommend

improvements in the design dimensions of the canal outlets and recommend operation strategies for the canal under

varying irrigation demand.

THE RESEARCH SITE

The model was applied to the Shingrai Minor located on the Abazai Branch of the USC, which receives water

from the Swat River at the Amandara Headworks. It was originally designed for a discharge of 68.6 cumecs

(2420 cusecs) to irrigate an area of 127 500 ha (315 000 acres) of the Charsaddah–Mardan–Swabi Plain. The canal,

after traversing the narrow ridge of the Malakand hills through the unlined Benton Tunnel, eventually bifurcates at

Dargai into the two branches of Machai and Abazai (Figure 1).

The Abazai Branch is 26 km long. It has 9 minors and 5 distributaries (Table I). The design discharge of Abazai

branch is 17.3 cumecs. There are additionally 36 direct outlets from the canal. It does not have any radial gate cross

regulators for flow control. The only points of flow control on the Abazai Branch are the intake, the secondary

offtakes and an escape structure located in the tail of Abazai Branch.

Copyright # 2006 John Wiley & Sons, Ltd. Irrig. and Drain. 55: 445–458 (2006)

DOI: 10.1002/ird

446 A. R. GHUMMAN ET AL.

Shingrai Minor takes off from the left side of the Abazai Branch of the USC at Reduced Distance (RD) 12 599 m

and is the first major secondary canal (Figure 2). It has a length of 5289 m and design discharge of 0.84 cumecs. It

has 13 outlets of which 11 are short-crested crump weirs (Bos, 1976), and two are open flumes. One of the open

flumes was designed as an Adjustable Orifice Semi Module (AOSM) but was constructed as an open flume. All the

outlets are fixed structures with no adjustable parts and the discharge through these outlets is entirely dependent on

the water depth above their sills. It has a culturable command area of 1170 ha. Most of the canal is lined, with

trapezoidal shape and a longitudinal slope of 0.0005. Shingrai Minor is representative of the medium-sized

Table I. Secondary canals of Abazai Branch

Name of canal Offtake RD (m) Length (m) Design discharge (m3 s�1) Outlets

Mehrdi Minor Abazai (7287) 1829 0.14 5Shingrai Minor Abazai (12599) 5289 0.84 13Pir Sadu Disty Abazai (14207) 9868 2.77 19Qutab Garh Minor Pir Sadu (2145) 5259 0.83 15Ghanu Minor Pir Sadu (7195) 3152 0.43 4Harichand Disty Abazai (17378) 8274 1.44 16Sharif Dheri Minor Harichand (2605) 4780 0.4 9Bariband Disty Abazai (23933) 26962 5.38 52Bahram Dheri Disty Abazai (22085) 14276 2.58 25Nasrat Zai Minor Bahram Dheri (11402) 6183 1.16 14Barazai Minor Bahram Dheri (10274) 3963 0.40 5Amir Abad Disty Abazai (26220) 12302 2.89 23Bajor Minor Amir Abad (1509) 2591 0.59 7Kiramat Minor Amir Abad (3460) 2754 0.54 11

Figure 1. Map of the Upper Swat Canal


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NUMERICAL MODELLING FOR MANAGEMENT OF CANAL IRRIGATION 447

secondary canals of the Abazai Branch, in design, water allowance and discharge. It was designed for cropping

intensities of more than 180%. The water allowance of Shingrai Minor is 0.7 l s�1 ha�1 (6 mm d�1), which is

sufficient to meet the peak irrigation requirements in the months of May and June. The irrigation demand varies

throughout the year from a maximum in May/June to the lowest in winter months.

OPERATIONAL PRINCIPLES

According to the operational principles of the Irrigation Department, 70% of the design discharge represents the

winter demand and 55% of the design discharge is the minimum threshold discharge (Government of NWFP, 1992).

A comparison of the gross irrigation requirements (Swabi SCARP Consultants, 1991) for cropping intensity of

180%, shows that the demand frequently drops below 70% of design discharge (Figure 3). The supply and demand

are both considered zero in the month of January due to the annual canal closure period and the demand in January

is added to the demand in December. Throughout the year the variation in irrigation requirements indicates the need

for operation of the canal at discharges below 70% of design discharge.

Actual operation of the canal was monitored for five months on a daily basis from August till December (Shah,

2000). During this period the canal was supplied close to its design discharge but the demand varied between 5 and

1.6 mm d�1. The interference from the Irrigation Department was minimal, except that four rotations of one week

each were introduced in November and December.

DESIGN OF CANAL OUTLETS

The discharge through a fixed weir outlet depends on the water level (head) in the canal. The discharge through an

orifice outlet depends on the difference of head in the canal and in the watercourse downstream of the outlet (Bos,

1976). So for weir-type outlets to draw the design discharge the width, crest height of the outlet and the water level

in the canal are important. Similarly for the orifice, the area of outlets opening and the upstream head are important

factors.

A comparison of the design and actual dimensions of the outlets indicated that nine outlets were constructed

according to their design. One outlet was designed as an AOSM but actually constructed as an Open Flume (Ali,

1993) having no roof block.

A number of errors can result in the poor performance of canal outlets. These can be due to design, construction,

and interference by stakeholders. These errors require rectification for the canal to be able to supply discharges to

all its outlets in a fair manner. In this study mainly design and construction errors were observed.

Figure 2. Schematic map of Shingrai Minor


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DATA COLLECTION

Data from field measurements taken in 1999 were used. The data involved measurement of water levels in the canal

along all the outlets and the head regulator of the canal. The head regulator and all the outlets were calibrated

through regular flow measurements, and the discharge coefficients were computed. All the canal design data were

collected from the Irrigation Department and verified through field measurements. The period of data collection

was from August till December. All the geometric and hydraulic data were reconfirmed in December 2004 through

survey and measurements.

CANALMAN MODEL

CANALMAN software implicitly solves the Saint-Venant equations of continuity and motion (Strelkoff, 1969)

for one-dimensional unsteady open-channel flow in a branching canal system. Computational nodes are used

internally by the model, and they are automatically inserted along the length of a canal reach, between the system

layout nodes (Merkley, 1997). CANALMAN was evaluated by the ASCE Task Committee on Hydraulic Models

along USM, MODIS, DUFLOW and CARIMA, and found to be reasonably accurate (Dinshaw and Schuurmans,

1993).

MODEL CALIBRATION AND VALIDATION

The model was calibrated using simulated and measured water levels in the canal reaches at full supply (846 l s�1).

Optimal values of the Manning’s roughness coefficient (n) and outlet discharge coefficients (Cd), were determined

so that simulated values become close to the measured values. The head regulator and outlets were calibrated by

Figure 3. Supply and irrigation requirements for Shingrai Minor


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development of head–discharge relationships between water levels in the canal above the crest of the outlets and

discharges through the outlets. Another data set collected at 750 l s�1 was used for validation of the model for

Shingrai Minor.

Model accuracy for the calibration and validation was determined by calculating the model efficiency (ME) as

follows:

ME ¼ ðST� SEÞ=STwhere

ST ¼X

ððSimulatedDepth� ðX

ðMeasuredDepthÞ=nÞ2Þ

SE ¼X

ðSimulatedDepth�MeasuredDepthÞ2

The results of model calibration are presented in Figure 4. The Manning n values used in the calibration were

between 0.016 and 0.018 for lined reaches and 0.023 for unlined reaches. A model efficiency of 92% was obtained.

For validation of the model the model efficiency was 95%. Figure 5 shows the measured and simulated outlet

discharges. The differences between the simulated and measured outlet discharges were less than 5 l s�1.

SIMULATION OF OPERATIONAL SCENARIOS

Five different operational modes were assessed in order to determine the performance levels. The operational

modes assessed for Shingrai Minor were as follows:

1. Design full supply.

2. 80% of the design discharge.

3. 70% of the design discharge, which is considered to be close to the winter demand.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

6000500040003000200010000

RD (m)

Dep

th (

m)

Measured

Simulated

Figure 4. Calibration of model with measured and simulated water levels at 846 l s�1


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4. 50% of the design discharge; to assess if the canal could be operated at low discharge when the requirements are

low.

5. Closure of the canal at night; to assess if night closure of the canal was a feasible option in the periods of low

requirement.

PERFORMANCE ASSESSMENT

Performance of canal outlets was evaluated under the existing outlet configuration and the modified configuration,

at four operational levels. Delivery performance ratio (DPR) was used as the performance indicator, which is an

expression of the actual discharge divided by the target discharge at any location in an irrigation system (Murray-

Rust and Snellen, 1993).

Performance of outlets was considered good if it remained within �10% of the target discharge for the outlet,

which is the criterion used by the Irrigation Department (Government of NWFP, 1992). An additional performance

level of �30% was used (Murray-Rust and Halsema, 1998). Below this the performance of an outlet was

considered unacceptable.

PERFORMANCE WITH THE EXISTING OUTLET DIMENSIONS

At 100% discharge, 7 outlets were drawing within �10% of their design (Figure 6). At 80 and 70% discharges 5

outlets could receive within �10% of their revised target discharges. At 50% discharge only 3 outlets had

satisfactory performance. Using a performance level of �30%, 8 outlets could draw satisfactory discharges under

100, 80 and 70%.While at 50% 7 outlets could draw within 30% of the modified discharges. Performance of outlets

0

20

40

60

80

100

120

6000500040003000200010000

RD (m)

Dis

char

ge (l

/s)

Measured

Simulated

Figure 5. Calibration of model with measured and simulated outlet discharges


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1, 3 and 4 was unsatisfactory even at �30% performance level under most of the discharges. These outlets were

overdrawing. On the other hand outlets 5, 8 and 13 could draw less than their allocation.

The overall performance of canal was not high even under full supply level. From an operational point of view it

was feasible to operate the system at 70% of the full supply. At this discharge it was possible for all the outlets to at

least draw discharges with which farmers could irrigate, i.e. more than 15 l s�1. At 50% discharge three outlets drew

less than 15 l s�1. At such low discharges interference by the farmers has been observed. In this situation they

usually place temporary stone weirs across the canal to raise the water level and get more water into the outlet. This

type of interference represents the desire of farmers to irrigate their fields quickly rather than to stay for a long time

in the field irrigating.

PERFORMANCE WITH MODIFIED OUTLET DIMENSIONS

Outlet dimensions were modified to achieve a better match between the observed discharge through the outlet and

the target discharge. This was done by running the CANALMAN model for several iterations. Those modified

dimensions were selected at which the simulated discharges became equal to the design discharges. Two outlets

were provided with roof blocks to convert them from weirs to orifices. This reduced their sensitivity and thus

became less sensitive to fluctuations in water levels in the canal. For the rest of the outlets the widths were modified

(Table II).

At a performance level of �10%, all the outlets had good performance with DPR close to 1 at 100% of design

discharge (Figure 7). Performance of 5 outlets was good at all the discharges, while 9 outlets performed well above

50% discharge. With a performance level of �30%, all the outlets showed good performance with only 4 outlets

showing low performance at only 50% canal flow.

Under the existing configuration, outlet 4 was highly sensitive to low discharges in the canal. The reason was its

construction as an open flume, although it was designed as an AOSM. It can be seen that the performance of outlet 4

did show improvement after modification; its DPR was still higher at low discharge in the canal.

0.00

0.50

1.00

1.50

2.00

2.50

1R 2R 3L 4L 5R 6R 7R 8R 9L 10L

11R

12T

L

13T

F

Outlet

DP

R (

%)

100% Discharge

80% Discharge

70% Discharge

50% Discharge

Figure 6. Delivery performance ratio at different discharges with existing outlet configuration


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OUTLET DISCHARGES WITH ACTUAL AND MODIFIED OUTLET DIMENSIONS

Discharges of the outlets were compared under actual and modified dimensions for our different operational levels

(Figures 8–11). The ideal water allowances are represented by the horizontal lines. The results indicated an overall

improvement in the discharges of the outlets. However, at 50% discharge due to lowwater level in the canal, outlet 4

behaves like a weir and draws more water. Outlets 6 and 8 cannot get their allocated discharges at 50% discharge

due to low downstream slopes in the watercourses.

Table II. Actual and modified outlet dimensions

Outlet Type Design Actual Modified

RD (m) No Design Actual(existing)

Modified Width(cm)

Height(cm)

Width(cm)

Height(cm)

Width(cm)

Height(cm)

18 1R1 Crump Weir Crump Weir AOSM 21.6 – 21.0 – 17.0 15.01253 2R Crump Weir Crump Weir Crump Weir 21.0 – 30.0 – 26.0 –1254 3L2 Crump Weir Crump Weir Crump Weir 23.5 – 23.50 – 16.0 –1882 4L AOSM Open Flume AOSM 8.54 – 8.65 – 8.5 22.01886 5R Open Flume Open Flume Open Flume 8.23 – 8.23 – 11.0 –2907 6R Crump Weir Crump Weir Crump Weir 60.7 – 62.0 – 62.0 –2908 7R Crump Weir Crump Weir Crump Weir 20.7 – 21.0 – 16.0 –2910 8R Crump Weir Crump Weir Crump Weir – – 25.50 – 27.0 –3550 9L Crump Weir Crump Weir Crump Weir – – 18.0 – 18.0 –3554 10L Crump Weir Crump Weir Crump Weir – – 15.0 – 12.5 –5288 11R Crump Weir Crump Weir Crump Weir – – 45.0 – 30.0 –5290 12TL Crump Weir Crump Weir Crump Weir – – 18.0 – 14.0 –

1R¼ right outlet.2L¼ left outlet.

0.00

0.50

1.00

1.50

2.00

2.50

1R 2R 3L 4L 5R 6R 7R 8R 9L 10L

11R

12T

L

13T

F

Outlet

DP

R (

%)

100% Discharge

80% Discharge

70% Discharge

50% Discharge

Figure 7. Delivery performance ratio at different discharges with modified outlet configuration


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The main errors in the outlets which caused underperformance were either in design or construction. Outlet 1R

was designed as a Crump Weir, although it should have been designed as an AOSM outlet. Outlet 2 R contained a

design as well as a construction error. Outlets 3, 5, 11 and 12 had design errors while outlet 4 was a construction

error.

OPENING AND CLOSURE OF CANAL

From the previous sections it is evident that there is a need to operate the canal at discharges lower than 80%

of the design discharge. But on the other hand the performance of canal at discharges below 80% is not

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1R 2R 3L L4 5R R6 7R 8R L9 10L 11

R LT21 1FT3

Outlets

l/s/h

a

Allocation

Actual

Modified

Figure 9. Allocated, actual and modified discharge at 80% of design discharge at 677 l s�1

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1R 2R L3 L4 5R 6R 7R 8R L9 10L 11

R21

LT1

FT3Outlets

l/s/h

a

Allocation

Actual

Modified

Figure 8. Allocated, actual and modified discharge at design discharge of 846 l s�1


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satisfactory. An additional operational option of opening and closing of the canal was explored using

hydraulic modelling. The response of the canal was studied with the discharge in the canal initially zero and

then it was increased to full supply. This is the situation of opening a closed canal and bringing it to full

supply. The whole canal was able to attain steady state in 3.5 h. After this time all the outlets of the canal were

drawing the maximum discharge and were in steady state (Figure 12). The simulation of canal closure

indicates that for the tail outlets of the canal, flow would be available for up to 3 h after closure of the Shingrai

Minor (Figure 13).

Field observations have shown that in periods of low demand farmers who have their irrigation turn at night

start to skip their night turns and instead irrigate in the day-time. Because farmers do not irrigate at night in

periods of low demand irrigation water is potentially wasted during the night in most of the secondary canals

and the shorter lag times involved in filling medium and small secondary canals. An additional strategy is

0.00

0.20

0.40

0.60

0.80

1.00

1.20

R1 R2 3L L4 R5 6R 7R R8 9L L01 1R1

1LT2

FT31Outlets

l/s/h

a

Allocation

Actual

Modified


0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

R1 R2 L3 L4 5R R6 R7 R8 9L 01L

1R1

12LT 31

FTOutlets

l/s/h

a

Allocation

Actual

Modified



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0

20

40

60

80

100

120

300250200150100500

Elapsed Time (min)

Flo

w R

ate

(l/s

)1R

2R

3L

4L

5R

6R

7R

8R

9L

10L

11R

12TL

Figure 12. Outlet hydrographs after opening empty canal at full supply

0

20

40

60

80

100

120

300250200150100500

Elapsed Time (min)

Flo

w R

ate

(l/s

)

1R

2R

3L

4L

5R

6R

7R

8R

9L

10L

11R

12TL

Figure 13. Outlet hydrographs after closing the steady state canal at full supply


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proposed under which all the medium and small secondary canals of the system in the head and middle

reaches can be closed at night and reopened during the day, in November and December. This will ensure

water saving at night.

CONCLUSIONS

The study demonstrates the usefulness of hydrodynamic models in understanding the behaviour of a canal. The

one-dimensional hydrodynamic model CANALMAN was applied to a secondary canal in the Upper Swat Canal

Irrigation System in the North West Frontier Province of Pakistan.

The model was calibrated on the maximum design discharge of 846 l s�1. After calibration of the model,

the influence of modification in outlet dimensions was evaluated at 100, 80, 70 and 50% of design discharge.

The modifications in outlet dimensions did improve the overall performance of the canal. However, the best results

were obtained at full supply and 80%. Operation of the canal at discharges below 80% of the design supply cannot

be recommended. An additional operational option of opening and closing the canal during the day and night

respectively has been recommended at a time when the demand is low as an alternative to operation of the canal at

discharges below 80% of the design discharge.

The following main conclusions can be drawn from the study:

1. CANALMAN is a suitable model for evaluation of secondary canals.

2. Modifications in outlet dimensions improved the performance of the canal.

3. Operation of the canal at discharges below 80% of the full supply is not recommended in such canals even after

outlet modification.

4. Opening and closure of the canal provides an alternative for operation of the canal at lower than 80% discharges.

ACKNOWLEDGEMENTS

We would like to thank the Biological and Irrigation Department, Utah State University, Utah Logan, USA, for

making the CANALMAN software freely available which was used in this study. We also appreciate the excellent

data collected by Mr Muslim Shah during his MSc study at the Department of Water Management, NWFP

Agricultural University Peshawar. The cooperation of the Irrigation Department is also greatly appreciated in

providing the design data and drawings of the Shingrai Minor. Special thanks go to the International Water

Management Institute Pakistan for providing the digitized map of the Upper Swat Canal Irrigation System.

REFERENCES

Ali I. 1993. Irrigation and Hydraulic Structures. Institute of Environmental Engineering and Research, NED University of Engineering and

Technology: Karachi, Pakistan.

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Management, NWFP Agricultural University, Peshawar, Pakistan.

Bos MG. 1976. Discharge Measurement Structures. ILRI Publication No. 20 (Third revised edition 1989). International Institute for Land

Reclamation and Improvement: Wageningen, The Netherlands.

Dinshaw NC, Schuurmans W. 1993. Informed usage and potential pitfalls of canal models. Journal of Irrigation and Drainage Engineering,

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Government of NWFP. 1992. Manual of Operation and Maintenance of Irrigation Systems. NWFP Government Printer: Peshawar.

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Drainage Systems 19(4).

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use of numerical modelling for management of canal irrigation water

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