( CNN ) -- China and India need to reach agreement on how they will manage water from one of the world 's great rivers -- the Yarlung-Zangbo-Brahmaputra -- before it becomes another serious impediment to relations between the two Asian heavyweights . Water scarcity already affects large parts of China and India . As their populations grow and income levels rise , forcing up demand for water-intensive food such as meat , the supply situation will worsen . Inevitably , that means tension over water resources . There is a regional precedent for a bilateral water treaty : bitter rivals India and Pakistan , under prodding from the World Bank , signed the Indus Waters Treaty in 1960 to cover water use from the Indus and five other rivers that flow through the two nations . While far from perfect , the treaty has given farmers and other users in both countries a framework on which they can make crop production and hydropower decisions . Infographic : The secret life of drinking water . Already , China 's construction of a 540-megawatt hydropower dam on the Yarlung-Zangbo , which flows for 1,700 kilometers ( 1,050 miles ) across the southern Tibetan plateau before it enters Indian territory and becomes the Brahmaputra , is cause for concern in New Delhi . The dam , known as the Zangmu , is due for completion in 2015 . While the Zangmu dam is a relatively small project , there is something much bigger on the horizon : a 38,000-megawatt dam at Motuo , near the river 's `` Great Bend , '' which potentially could reduce the volume of water flowing into India and Bangladesh . While China maintains that any dams it builds on its part of the river will have little downstream impact , up to 150 million people living in eastern India and Bangladesh could be affected . Almost half the world 's population -- the 3.5 billion people living in Central , South and East Asia -- relies on water from the great rivers that rise in the Himalayas , the Tibetan plateau , and the Tibetan ethnic areas of China . The way the most important of these rivers -- the Indus , Ganges , Brahmaputra , Salween , Yangzi , Yellow and Mekong -- are used carries the potential for conflict as countries struggle with the challenges of rising populations , pressure on farming and food supplies , diminishing water quality and demand for hydropower . China has always been prepared to move mountains and people to achieve its economic and social goals . The $ 25 billion Three Gorges Project , built in the upper reaches of the Yangzi River between 1994-2011 , is testament to that . As many as 1.3 million people were relocated so the dam could be built , both to generate power and as a flood mitigation measure . Its full ecological impact is yet to be determined . Now China is working on its massive $ 60 billion South-North Water Diversion Project that involves the country 's two most important rivers -- the Yangzi and the Yellow -- plus numerous tributaries , canals and other rivers such as the Huai and Hai . It is one of the biggest civil engineering projects conceived anywhere in the world . First formulated by Chairman Mao Zedong in 1952 as a way to move water from the southern half of China to the dry but heavily populated north , the three-part scheme took its first steps forward in 2002 when work began on the 1,155 kilometer ( 716 mile ) eastern route . This part of the project , scheduled for completion in 2013 , will take water from the Yangzi River via channels to Shandong province , and then by a tunnel under the Yellow River and onwards to the coastal city of Tianjin . Work on the central route began late in 2003 . This 1,267 kilometer ( 785 mile ) diversion is designed to take water from a reservoir on the Han River ( a tributary of the Yangzi ) along new canals on to Henan and Hebei provinces , and finally to Beijing . A trunk line will also serve Tianjin . Long-term , the western route is the one which causes the most concern , as it involves diverting water from tributaries of the Yangzi , including the Tongtian , Dadu and Yalong rivers , across the Bayankala Mountains to the Yellow River , to supply northwest China . While some experts doubt the western diversion will ever be built because of the massive cost and logistical challenges of tunnelling under a mountain range , China 's record in building mega-projects suggests otherwise . In March this year , Vice-Premier ( and likely premier in 2013 ) Li Keqiang told a State Council meeting that drought and water shortages in the north had held back economic development there . As a consequence , he said , the South-North diversion project was `` essential . '' In June , China announced it had begun work on a key part of the central route : a $ 1.4 billion , 45 kilometer tunnel to divert water from the Yangzi river to Beijing . The tunnel should be finished by 2014 . China has always moved faster than India ; that 's why the time for a water treaty is now . The opinions expressed in this commentary are solely those of Geoff Hiscock .
China , India need to agree on water management of Yarlung-Zangbo river . Precedent for this when India and Pakistan signed Indus Water Treaty in 1960 . Chinese construction of Zangmu dam already causing concern for New Delhi .