China has invested nearly USD 3.5 billion in water conservancy infrastructure in the past five years in Tibet, where it is also building a series of dams over Himalayan rivers like the Brahmaputra raising concerns of water shortage in lower-riparian states like India and Bangladesh.

The investment benefited about 1.8 million farmers and nomads by stabilising grain output, as well as ensuring safe drinking water and power supply in remote area, Tibet's water resources department said.

From 2011 to 2015, Tibet saw its capacity of water supply increase by 700 million cubic metres.

About 100,000 hectares of irrigation areas were created or improved. In addition, 773,000 rural residents, students and teachers and those in monasteries were provided with clean drinking water.

Hydropower relieved 270,000 people of difficulty in accessing electricity, it said.

China has been building major dams on Brahmaputra river to generate hydel power.

China has operationlised Zangmu hydroelectric project in October 2015 and three more were under construction.

While dams raised concerns of water shortages in India and Bangladesh which are lower-riparian states of Brahmaputra river, China says its dams were run-of-the-water projects to generate power and are not aimed at storing water.

Chinese officials say that special terrain and climate on the Tibetan plateau region are disadvantageous to agriculture.

Eighty per cent of rain in Tibet a year falls between June and September and 60 per cent of its land is in the arid and semi-arid zones.

To combat frequent flash floods and torrential rain in summer, more than 1,600 km of embankments were built and over 1,300 km of river improved during the past five years, state-run Xinhua agency reported.