LINING IMPACT ON WATER LOSSES IN WATERCOURSES Dr. M. Arshad Dr. Q. Zaman Dr. A. Madani

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

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) CHALLENGES

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

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

Source: World Bank, 2005

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

AVAILABILITY OF WATER AND LOSSES System component Available at Head (BCM) Loss (BCM) (BCM)Loss(%) % of total Inflow River system Canals Watercourses Field application Crop use 3722 Total100 Overall Irrigation System Efficiency 22.3%

WATERCOURSE LOSSES

FUTURE VISION OF PAKISTAN Year Population Water availability (Million) per capita (m 3 ) (Million) per capita (m 3 ) Water Scarcity Water Scarcity <1000 m 3 <1000 m 3

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

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

Experimental Site Experimental Site - Ghourdour Distributary (1.36m 3 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

Selected Watercourses Watercourse No. Designed discharge (L s -1 ) Total length (m) Average water depth (m) Bottom width (m) 26680/R (unlined) /R (unlined) /R (lined) /L (lined)

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

Watercourse No. TestInflow rate (L s -1 ) Outflow rate (L s -1 ) Section length (m) 26680/R Average /R Average /R Average /L Average

W/C No. TestLoss (L s -1 Per 100m) Percentage loss (flow per 100m length) Loss (m 3 s -1 per million.m 2 ) Total loss (L s -1 ) 26680/R (unlined) Average /R (unlined) Average /R (lined) Average /L (lined) Average

W/C No /R (unlined) W/C No /R (unlined)  liter per second  Losses - 68% of the flow W/C No /R (unlined) W/C No /R (unlined)  liter per second  Losses - 64% of the flow W/C No /R (lined) W/C No /R (lined)  liter per second  Losses - 52% of the flow W/C No /L (lined) W/C No /L (lined)  2.98 liter per second  Losses - 35% of the flow Results and Discussions

Comparison of Water Losses Between Unlined and Lined Watercourses Watercourse No.Average loss (%)Average loss difference (%) UnlinedLined 26680/R /R /R /L-35 Average

Unlined watercourses - water losses ranged from 64 to 68% Unlined watercourses - water losses ranged from 64 to 68% Lined watercourses - water losses ranged from 35 to 52% Lined watercourses - water losses ranged from 35 to 52% Comparing the average water loss - 66% (unlined) to the 43.5% (lined) watercourses Comparing the average water loss - 66% (unlined) to the 43.5% (lined) watercourses Watercourses - Same type of soil hydraulic characteristics Watercourses - Same type of soil hydraulic characteristics Maintenance conditions - Very poor Maintenance conditions - Very poor Discharge of watercourse was greater than its capacity. Discharge of watercourse was greater than its capacity. Water losses - higher due to spilling Water losses - higher due to spilling Lining reduced water loss by 22.5%

Watercourse 25373/R - Lined about 10 years before Watercourse 25373/R - Lined about 10 years before Excess leakage of water Excess leakage of water  Frequent cracks in walls  Eroded mortar  Structural failure of the lined walls Capacity was reduced 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 Condition of Lined Watercourses

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

THANKS