LINING IMPACT ON WATER LOSSES IN WATERCOURSES

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LINING IMPACT ON WATER LOSSES IN WATERCOURSES

• Dr. M. Arshad
• Dr. Q. Zaman
• Dr. A. Madani

2
BACKGROUND

• Rural population (68 ) depends on agriculture
• Employs over 70 of labour force
• 80 of foreign exchange earnings
• Contributes 24 to GNP

3
CHALLENGES

• Increase food production with
• Less water (Countries with limited water and land
  resources)
• Effective and sustainable use of water
  (agriculture)
• Require urgent and immediate solution (in view of
  intensifying competition)

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LAND RESOURCES OF PAKISTAN

• Geographical area 79.3 Mha
• Cultivable area (suitable for agriculture)
  31.2 Mha
• Cultivated area (Irrigated Barani) 22.1 Mha
• Irrigated area by all sources
  18 Mha
• Additional area (Need to be Irrigated) 9.2
  Mha
• Population of Pakistan 170 Million

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WATER RESOURCES OF PAKISTAN

• Rainfall
• Annual rainfall (125mm in South-East to 750mm
  North-West)
• Total water generated by rainfall is 32 BCM
• Contribution to crops is 10-20
• Groundwater
• Exploitation of Groundwater is 59 BCM
• 7,00,000 private tubewells
• 40 of total supply at farm-gate
• Surface Water Resources
• Total Inflow is 171 BCM
• Tarbela (10.38 BCM - 485 ft),
• Mangla (5.90 BCM - 380 ft)
• 48 Canals (61000 km), 19 Barrages
• 1,70,000 Watercourses (1.6 Million km)

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Source World Bank, 2005
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PROBLEMS OF IRRIGATION SYSTEM

• Inefficiency in conveyance and application of
  water
• Inadequacy of available water supplies
• Inequity of distribution of water
• Unreliability of water supplies
• Increased cropping intensity
• Inadequacy of drainage facilities
• Inadequate and diminishing storage capacities

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AVAILABILITY OF WATER AND LOSSES
System component Available at Head (BCM) Loss (BCM) Loss () of total Inflow
River system 171 42 24 24
Canals 129 34 27 20
Watercourses 95 43 45 25
Field application 52 15 28 9
Crop use 37 22

Total 100
Overall Irrigation System Efficiency 22.3
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WATERCOURSE LOSSES
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FUTURE VISION OF PAKISTAN

• Year Population Water availability
• (Million) per capita (m3)
• 1951 34 5300
• 1961 46 3950
• 1971 65 2700
• 1981 84 2100
• 1991 115 1600
• 2000 148 1200
• 2013 207 850
• 2025 267 659
• Water Scarcity
• lt1000 m3

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STRATEGIES TO MITIGATE WATER SHORTAGE

• Long Term
• Construction of new reservoirs
• Policy for the Groundwater exploitation etc.
• Medium Term
• Lining of watercourses to save good quality water
• Short Term
• Adopt pressurized irrigation techniques and RCT

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Objectives

• To assess and measure the water losses in unlined
  and lined watercourses on the same command
• To analyze the impact of lining on the water
  losses from the watercourses

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Experimental Site

• - Ghourdour Distributary (1.36m3 s-1) of Upper
  Gogera Branch of Lower Chenab canal irrigation
  system
• Ghourdour Distributary
• 20.7 km long
• 43 watercourses
• Command area of 8251 ha
• Rice-wheat agro-ecological zone
• Major crops (summer)- Rice, sugarcane, and forage
  
• Major crops (winter)- Wheat, sugarcane and forage

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Selected Watercourses
Watercourse No. Designed discharge (L s-1) Total length (m) Average water depth (m) Bottom width (m)
26680/R (unlined) 37 2439 0.305 0.406
28000/R (unlined) 17 1909 0.152 0.611
25373/R (lined) 41 5727 0.279 0.508
28915/L (lined) 7 1273 0.191 0.711
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Measurement of Water Losses

• Inflow-outflow method
• Cutthroat flume used (at upstream and downstream)
• 0.20 m X 0.91 m
• Section of 244m to 305m length (to measure the
  water losses)
• Three replications of water flow measurements
  were made

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Watercourse No. Test Inflow rate (L s-1) Outflow rate (L s-1) Section length (m)
26680/R 1 2 3 28.34 34.01 34.01 24.09 29.76 29.76 305 305 305
26680/R Average 32.02 27.77 305
28000/R 1 2 3 17.00 19.84 19.84 14.17 17.00 17.00 244 244 244
28000/R Average 18.99 16.15 244
25373/R 1 2 3 36.84 34.01 35.43 32.59 31.17 32.59 305 305 305
25373/R Average 35.43 32.02 305
28915/L 1 2 3 8.50 8.50 8.50 7.65 7.65 7.65 274 274 274
28915/L Average 8.50 7.65 274
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W/C No. Test Loss (L s-1 Per 100m) Percentage loss (flow per 100m length) Loss (m3 s-1 per million.m2) Total loss (L s-1)
26680/R (unlined) 1 2 3 1.39 1.39 1.39 4.91 4.10 4.10 10.95 10.95 10.95 19.27 23.13 23.13
26680/R (unlined) Average 1.39 4.37 10.95 21.77
28000/R (unlined) 1 2 3 0.93 0.93 0.93 5.47 4.69 4.69 8.93 8.93 8.93 10.88 12.70 12.70
28000/R (unlined) Average 0.93 4.94 8.93 12.15
25373/R (lined) 1 2 3 1.39 0.93 0.93 3.78 2.73 2.62 13.04 8.72 8.72 19.16 17.69 18.42
25373/R (lined) Average 1.11 3.05 10.41 18.42
28915/L (lined) 1 2 3 0.28 0.28 0.28 3.28 3.28 3.28 2.56 2.56 2.56 2.98 2.98 2.98
28915/L (lined) Average 0.28 3.28 2.56 2.98
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Results and Discussions

• W/C No. 26680/R (unlined)
• 21.77 liter per second
• Losses - 68 of the flow
• W/C No. 28000/R (unlined)
• 12.15 liter per second
• Losses - 64 of the flow
• W/C No. 25373/R (lined)
• 18.42 liter per second
• Losses - 52 of the flow
• W/C No. 28915/L (lined)
• 2.98 liter per second
• Losses - 35 of the flow

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Comparison of Water Losses Between Unlined and
Lined Watercourses
Watercourse No. Average loss () Average loss () Average loss difference ()
Watercourse No. Unlined Lined
26680/R 68 -
28000/R 64 -
25373/R - 52
28915/L - 35
Average 66 43.5 22.5
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Lining reduced water loss by 22.5

• Unlined watercourses - water losses ranged from
  64 to 68
• Lined watercourses - water losses ranged from 35
  to 52
• Comparing the average water loss - 66 (unlined)
  to the 43.5 (lined) watercourses
• Watercourses - Same type of soil hydraulic
  characteristics
• Maintenance conditions - Very poor
• Discharge of watercourse was greater than its
  capacity.
• Water losses - higher due to spilling

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Condition of Lined Watercourses

• Watercourse 25373/R - Lined about 10 years before
• Excess leakage of water
• Frequent cracks in walls
• Eroded mortar
• Structural failure of the lined walls
• Capacity was reduced
• Silting
• Overtopping of water flows
• ? In general these data show that rates of loss,
  while influenced by soil texture, are even
  more strongly influenced by the presence of
  cracks in lining

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Conclusions

• ?Lining reduced water loss by 22.5
• ?The excess leakage of water through the
  watercourses is due to cracks, eroded mortar and
  structural failure of the lined walls.
• ?The capacity of watercourse is also reduced due
  to silting, resulting in overtopping of flows at
  many locations
• ?Consequently, it is concluded that the lining of
  watercourse can not effectively save the water
  losses and ultimately results in higher water
  loss than the normal unless properly maintained

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• THANKS