The Indus Basin Irrigation System, Pakistan
The world's largest contiguous irrigation network, feeding Pakistan from the Indus rivers but plagued by salt, waterlogging and unequal access.
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- Pakistan
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Evidence
8 figures, each threaded to its source
Land irrigated by the system
14 millionhectares
2 sources
“the system irrigates over 14 million hectares of land”
Major link canals moving water between rivers
12canals
2 sources
“Water is transferred between rivers through 12 major link canals”
Length of minor canals
64,000km
2 sources
“64,000 km of minor canals distributing water across the countryside”
Extra farmland created by irrigation
40%
2 sources
“It has increased the amount of land available for agriculture by 40%”
Canal command area hit by waterlogging
35%
“waterlogging still afflicts 35 percent of the IBIS canal command area, mostly in the province of Sindh”
Salt added to the basin by irrigation each year
16 milliontonnes
“Irrigation adds around 16 million tons of salt to the Indus basin every year”
Irrigated area threatened by salinity
43%
“threatening soil health and agricultural production in up to 43 percent of the irrigated area”
Year of the Indus Waters Treaty
1960year
“The Indus Waters Treaty was signed in 1960 after nine years of negotiations between India and Pakistan with the help of the World Bank”
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Background
Most of Pakistan is too dry for reliable farming, yet the country must feed one of the largest populations in the world. The answer is the Indus Basin Irrigation System, the biggest contiguous irrigation network on Earth. Meltwater and monsoon rain flow down the Indus and its tributaries from the Himalaya and Karakoram mountains. Barrages built across the rivers raise the water level and divert it into canals, while major link canals carry water from the western rivers to farmland in the east. This layout follows the Indus Waters Treaty of 1960, which gave the eastern rivers to India and the western rivers to Pakistan. The network irrigates over 14 million hectares in Punjab and Sindh and grows most of the nation's wheat, rice, cotton and sugar cane. But decades of flood irrigation have caused waterlogging and salinisation, water is shared unequally between farmers, and the whole system depends on rivers that climate change is making less predictable.
Causes
A dry land with big rivers
Much of Pakistan's plain receives too little rain for dependable crops, yet the Indus and its tributaries carry huge volumes of meltwater from high mountains. Irrigation was the obvious way to match the two, and canal building that began under British rule grew into a network serving the whole basin.
Partition and the 1960 treaty
When India and Pakistan separated in 1947, the rivers feeding Pakistan's canals suddenly crossed a hostile border. The Indus Waters Treaty of 1960 gave India the eastern rivers and Pakistan the western ones, so Pakistan built new dams, barrages and link canals to move western river water to land the eastern rivers once supplied.
Feeding a growing population
Pakistan's population has multiplied since independence, and farming still employs a large share of its workers. Expanding irrigation increased the amount of land available for agriculture by 40 per cent, letting farmers grow water hungry staples such as wheat, rice and sugar cane at a scale rain alone could never support.
Effects
Primary
- Over 14 million hectares of farmland are irrigated, the largest contiguous irrigated area in the world.
- Barrages and 12 major link canals redistribute river water across the Punjab and Sindh plains through about 64,000 km of smaller canals.
- Irrigation increased the land available for agriculture by 40 per cent.
Secondary
- Most of Pakistan's wheat, rice, cotton and sugar cane is grown on irrigated land, underpinning both food supply and exports.
- Canal water recharges groundwater, which millions of tube wells now pump to top up supplies.
- Whole cities and industries, from textiles to sugar milling, depend on crops the canals make possible.
Social
- Millions of farming families earn their living from irrigated land.
- Farmers at the tail ends of canals receive less water than those upstream, fuelling disputes and rural inequality.
- Poor drinking water and failing harvests in salt affected areas add to rural poverty and poor health.
Economic
- Irrigated agriculture is a foundation of Pakistan's economy and its biggest employer of rural labour.
- Yield losses from waterlogged and salty soils cost farmers a growing share of their income.
- Maintaining thousands of kilometres of ageing canals and barrages is a constant drain on public funds.
Environmental
- Waterlogging afflicts 35 per cent of the canal command area, mostly in Sindh.
- Irrigation adds around 16 million tonnes of salt to the basin every year, threatening up to 43 per cent of the irrigated area.
- So much water is withdrawn that little reaches the Indus delta, where mangroves and fisheries are collapsing.
- Heavy pumping is depleting and polluting groundwater in many districts.
Responses
Immediate
- Drainage schemes pump water from waterlogged land and carry salty water away from fields.
- Canal lining and watercourse improvement reduce the seepage that wastes water and raises the water table.
- Rotas called warabandi share canal water between farmers in fixed turns to limit disputes.
Long term
- Salinity control projects, begun with the SCARP tube well programmes, aim to lower water tables and flush salt from soils.
- Farmers are encouraged to adopt laser levelling, drip and sprinkler irrigation and less thirsty crops to cut water waste.
- Dams and reservoirs are being extended to store more floodwater, while treaty arrangements with India manage the shared rivers.
- Groundwater regulation and monitoring are being introduced to slow depletion and contamination.
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