FRESHWATER resources are under global stress for a variety of reasons. A spiralling population demands more water for crops, dairy and energy. Therefore, rivers are being fettered with storage and diversion structures. Endless thirst upstream deprives deltaic ecosystems of vital environmental flows. As rivers dry up, their deltas are suffocating. In one study, scientists examined 33 river deltas worldwide and concluded that 24 were experiencing environmental degradation. Some of these deltas bear a striking resemblance to the plight of the Indus delta.

The Yangtze river is the longest in Asia and the third-longest in the world. The basin provides about half of all the fish and two-thirds of the rice consumed in China. The river is dotted with thousands of storage sites, constructed since the 1950s. The Three Gorges Dam, the world’s biggest hydropower project, inundated 13 large cities, 140 towns and 326 villages, displacing over a million people. Massive upstream diversion has played havoc with its delta. Due to the lack of environmental flows, undiluted flows from industries and agricultural farms have increased pollution to perilous levels. The area’s wildlife is under severe stress, and its........

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