'Water tower' outflow almost doubles in five years

XINING－The amount of water flowing out of the Sanjiangyuan area, dubbed "Asia's water tower", has increased in recent years as a result of a warming climate and increased humidity.

The amount of water flowing out of Qinghai province, where Sanjiangyuan is located, reached 95.5 billion cubic meters last year, an increase of around 46.4 billion cu m compared with 2016.

The Sanjiangyuan area is home to the headwaters of three major rivers－the Yangtze, Yellow and Lancang, which is known as the Mekong after it flows out of China.

"Under the backdrop of global warming, the natural environment and hydrological regime in the Sanjiangyuan area are changing," said Li Yan, a member of a research team studying the Yangtze River and an official with Qinghai's hydrology and water resources measuring and reporting center.

Research into the runoff in Qinghai showed the increase in the amount of water flowing out of Sanjiangyuan was due to increased precipitation and melting glaciers, Li said.

Li said that the increasing outflow from Sanjiangyuan can provide basic conditions for the construction of water supply and water diversion projects and can also benefit residents in downstream provinces.

"However, further research on glacier degradation and permafrost melting should be conducted to grasp the changing of the outflow in the medium and long term," Li said.

More lakes

According to data gathered by researchers, the more than 11,000 lakes in the headwaters area of the Yangtze River cover a total area of 1,027 square kilometers, making it the world's largest and highest plateau lake cluster.

"Recent research indicated that the water quality of lakes around the headwaters of the Yangtze River remains good," said Xu Ping, deputy chief engineer with the Changjiang River Scientific Research Institute. "The area of lakes and wetlands in the region increased by 7.2 percent over the past four decades."

The headwaters area of the Yangtze River is getting warmer and more humid. In the past decade, the average temperature has increased by 1.4 C, and the amount of annual precipitation has risen by 39.6 millimeters when compared with the average figures over the previous 40 years, according to research data.

Glacier degradation and permafrost melting, triggered by rising temperatures and increased precipitation, also accelerated the expansion of the lake area, Xu said.

Tan Debao, deputy chief engineer at the Changjiang River Scientific Research Institute, said, "Although lakes and wetlands can regulate and control the outflow of rivers' headwaters and the regional climate, as well as provide important habitats for diverse creatures, the increased lake area and rising water levels will have adverse impacts on the ecosystem around the lakes and nearby infrastructure."

More attention should be given to studies of the lakes' expanding area and rising water levels to protect the ecosystem in the headwaters region, Tan said.

Xinhua