Monsoon rains and glacial ice melt provide water to major rivers that flow from the Himalayan region to the sea, providing water to Tibet, Pakistan, northern India, Nepal and Bangladesh. The flow of rivers like the Brahmaputra starting in the eastern Himalaya ─ fed mostly by the summer monsoon ─ could increase as climate change results in more moisture in the atmosphere. The flow of the Indus, however, comes from snow and glaciers, whose meltwater sustains people and ecosystems in the basin. An article in National Geographic explains in depth how climate change, poor management and population growth threaten the livelihoods of 270 million people in the Indus basin.
People used to be thankful for rivers, and many were worshipped. Now they are just a resource, and the effects of poor management can be seen in the form of inefficient engineering schemes, inequitable water sharing, and degraded ecosystems.
Added on to that, glaciers in the Himalayas are retreating as a result of global warming. While water flow in the Indus may increase at first, if temperatures continue to climb up, river flows are expected to decline after reaching a peak by 2050.
The effects of climate change have also revealed themselves with another impact: in 2010 severe flooding in the Indus River basin in Pakistan killed more than 1,600 people and caused damages worth $10 billion. Although rainfall projections in the Himalayan region are uncertain, extreme precipitations have increased. Pakistan, with 230 million people, is 144th out of 192 world countries in terms of greenhouse gas emissions per capita, but it bears a large share of climate change impacts.
Glaciers advance as they accumulate ice mass, but they can also move downhill when they start to melt and become unstuck. An immediate hazard caused by melting glaciers in the upper Indus Basin are glacial lake outburst floods, known with the acronym GLOF. Seven million in northern Pakistan are thought to be at risk of such floods.
In Pakistan and northern India, the largest irrigation system worldwide depends on the Indus. Before the independence of India and Pakistan, the British built dams on the Indus and tributaries to divert water into a vast irrigation network. Both countries signed the Indus Waters Treaty in 1960, dividing the river basin. More dams and canals were built afterwards, providing artificially cheap water.
In the Pakistani province of Sindh, irrigation water that has travelled 200 miles is used to grow chilies and other cash crops. But there are important water management problems: scarcity of canal water, unusually heavy monsoons and groundwater contaminated with fertilisers and arsenic. Arsenic occurs naturally in soils and also comes from fertilisers; heavy irrigation leaches it to groundwater. Moreover, child malnutrition is common in irrigated areas of Pakistan, where exports crops ─ namely cotton, making up more than half of the country’s foreign exchange earnings ─ take priority over food crops.
The way irrigation is managed is the source of many problems. Dams and canals provide cheap irrigation water, and fertile silt stays in reservoirs. Flood irrigation uses a lot of water, fertilisers and pesticides, since insect pests thrive in flooded fields and water washes the chemicals into the groundwater. Hassan Abbas, hydrogeologist in Punjab, estimates farmers use 10 times more water that needed. He calls for a radical rethinking of the system, and thinks climate change may be an incentive for a transition to solar power, drip irrigation, and restoration of wetlands and forests in the Indus Basin that would absorb floods.
The management challenges in the Indus River basin are many. Shared by India and Pakistan, China controls the river’s headwaters. The three countries have large populations that need the resources. The effects of climate change, with increased flooding and projected declines in flows, exacerbate the risks for agriculture and the growing population.