The river that holds a country together.

Fly over Punjab in late spring and the country looks like a drawing made with a ruler. Canals run straight for miles, fields sit in exact rectangles, and every line of green leads back, eventually, to one river. The Indus rises on the Tibetan plateau, cuts through the Himalaya and the Karakoram, and runs about 3,200 kilometres to the Arabian Sea near Karachi.¹ Most of what Pakistan grows depends on it.²

The first thing anyone who works on the Indus learns is that it is not one river. It is a system: the main stem and five great tributaries, fed by snowmelt and the monsoon, stitched together by barrages and link canals into one of the largest contiguous irrigation networks on earth.² The second thing they learn is that this system was cut in two in 1947.

A border drawn across the water

Partition placed the headwaters of several rivers in India and most of the irrigated land downstream in Pakistan. For thirteen years the two new countries argued over who could take how much. In 1960, after nearly a decade of talks brokered by the World Bank, Jawaharlal Nehru and Ayub Khan signed the Indus Waters Treaty in Karachi.³

The bargain was simple to state and hard to build. India got the three eastern rivers. Pakistan got the three western ones, and, financed through a fund administered by the World Bank, it built the dams and link canals needed to carry western water to land that used to drink from the east: Mangla on the Jhelum, finished in 1967, and Tarbela on the Indus, finished in 1976 and still among the largest earth-filled dams ever built.⁵

A treaty can divide a river. It cannot store one, and it cannot stop a river from changing underneath it.

Under strain

For more than sixty years the treaty outlasted wars and decades of hostility between its signatories, which is more than most agreements between rivals can say.³ Whatever its political future, the problems underneath it are physical and slow. Reservoirs fill with silt from the day they are closed, and lose storage every year. The glaciers that feed the upper Indus are part of a changing climate.⁷ Unlined canals lose water to seepage long before it reaches a field, and a growing population asks more of the same river every decade.⁶

None of this is secret. Engineers in both countries have described it for years. It is simply slower than the news, and harder to photograph than a signing ceremony.

What water security would take

Not one megaproject, but a hundred unglamorous ones: lining canals, measuring every flow in real time, pricing water so it is not wasted, recharging aquifers, dredging and maintaining what already exists. The engineering is known. The hard part, as ever, is deciding to do it, and paying for it before the shortage rather than after.

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