* The Sanjiangyuan area is located on the Qinghai-Xizang Plateau, which is known as the "roof of the world" and Asia's "water tower." Against the backdrop of climate change, the ecological and environmental changes there have become the focus of the scientific community.
* The number of aquatic species in the headwater region of the Yangtze River has been growing in recent years, showing that the overall water ecological environment in the region is improving, which is related to the rising temperature and increased water volume brought about by the warming and humidification of the Qinghai-Xizang Plateau.
* Meteorological monitoring shows that the warming rate in the headwater region has significantly accelerated over the past two decades. The annual average temperature over the past decade has risen by 1.4 degrees Celsius compared with the average temperature in the previous 40 years.
XINING, Aug. 24 (Xinhua) -- The headwater region of the Yangtze River -- known as Sanjiangyuan -- is a sensitive-response area for climate change and an ecologically fragile zone. Against the backdrop of climate change, the ecological and environmental changes there have become the focus of the scientific community, with experts gathering vast amounts of relevant data.
The Sanjiangyuan area is located on the Qinghai-Xizang Plateau, which is known as the "roof of the world" and Asia's "water tower." It is China's most crucial ecological security barrier and a strategic resource reserve, playing a vital role in water, ecological, climate and environmental security globally.
In July, more than 20 researchers from the country's water resources department and scientific research institutions set foot on the plateau's hinterland for an expedition to the Yangtze River's headwater region. During their 10-day trip, they conducted numerous observations and experiments, in the process identifying various changes in the environment, including an improved ecological environment, rising temperatures and shrinking glaciers.
IMPROVING ECOLOGICAL ENVIRONMENT
This is the sixth time that Qiao Qianglong, a 34-year-old researcher from the Changjiang River Scientific Research Institute (CRSRI), has participated in the expedition in the headwater region of the Yangtze River.
What surprised Qiao this year is that he found a gray-brown frog in the Chadan Wetland at an altitude of 4,800 meters nearby the southern source of the Yangtze River.
"Frogs are cold-blooded amphibians that generally do not survive in such a high-altitude and cold region," he said.
Experts also collected samples of headwater-region fish during last year's expedition. In recent years, expedition members have found the plateau loach in the Damqu River on many occasions, which has been confirmed to be the sixth species of fish in the southern source of the Yangtze River.
The number of aquatic species in the headwater region of the Yangtze River has been growing in recent years, showing that the overall water ecological environment in the region is improving, which is related to the rising temperature and increased water volume brought about by the warming and humidification of the Qinghai-Xizang Plateau, said Xu Ping, a senior expedition expert and chief engineer of the CRSRI.
According to water resources data from northwest China's Qinghai Province, the average annual self-produced water resources in the Yangtze River source area have reached 26.17 billion cubic meters over the past five years, which is more than 40 percent higher than the average figure from 1956 to 2016.
In recent years, the ecological environment protection of the Sanjiangyuan area has achieved remarkable results. Data from Qinghai's ecology and environment department shows that the water quality of the Yangtze River's mainstream in the province has remained in a Class-I or Class-II condition for many years.
"The increase of the water volume and the improvement of the water quality will not only help improve the water ecological regulation and storage capacity, but also better protect biodiversity in the Yangtze River source area," said Xu Ping, adding that more biological species will be discovered in the future.
MELTING GLACIERS
Fan Yue, a 30-year-old engineer from CRSRI, has participated in the expedition for three consecutive years.
Fan's main task is to measure the thickness of glaciers, an important global freshwater reserve resource and a sensitive indicator of climate change, on Mount Geladandong and the Dongkemadi glacier in the headwater region of the Yangtze River.
Meteorological monitoring shows that the warming rate in the headwater region has significantly accelerated over the past two decades. The annual average temperature over the past decade has risen by 1.4 degrees Celsius compared with the average temperature in the previous 40 years.
According to the expedition, glaciers in the Yangtze River source area are generally in a state of retreat, shrinking and thinning. Glacier detection has become one of the important tasks of the expedition in the Sanjiangyuan area in recent years.
"We can calculate the ice thickness based on the arrival time of the reflected wave and the propagation speed of the electromagnetic wave in the ice," Fan said, adding that expeditions have demonstrated that Mount Geladandong and the Dongkemadi glacier both have a tendency to shrink.
Zhou Yinjun, deputy director with the CRSRI's River Research Institute, said that the intensifying glacier melting will lead to seasonal floods, ice avalanches and other disasters, and may even weaken the river runoff replenishment function and induce a series of ecological problems.
According to the Meteorological Center of the Yangtze River Valley, the warming and humidification trend in the headwater region of the Yangtze River will continue in the future. It is expected that by the end of the 21st century, the average temperature in the area will rise by 2 to 4 degrees Celsius compared with the current level.
Against a background of climate change, glacier detection needs to be further strengthened. "We are able to accurately calculate the ice reserves and study the impact of climate change on glaciers through continuous detection and research," said Xu Ping.
YANGTZE RIVER PROTECTION
"The headwater region is like a human brain, which can influence the situation as a whole," said Xu, adding that the ecological environment of the source area plays a crucial role in maintaining the stability of the climate system, water resources security, biodiversity and ecosystem security along the Yangtze River.
In 1976, China organized its first scientific expedition to the headwater region of the Yangtze River. After overcoming many hardships, the expedition team finally traced the source of the Yangtze River to the foot of Mount Geladandong, which revised the length of the Yangtze River and confirmed it as the third-longest river in the world.
In order to gain a deeper understanding of the changes in the ecological environment in the source area of the Yangtze River, the CRSRI has carried out comprehensive scientific expeditions to the Sanjiangyuan area since 2012.
Over the years, the expedition has gradually expanded from the initial focus on hydrology, water and sand to hydrology and water resources, river evolution, water environment and ecology, soil and water conservation, and permafrost carbon migration in the water-source region.
The expedition has gone through three stages, namely, entering, studying and protecting the source of the river.
"The previous expeditions mainly focused on figuring out the overall situation of the river source area, while the current expeditions are to better protect the headwater region of the Yangtze River through the comparing of expedition data and studying the regular pattern of ecological changes," said Xu.
At present, the expedition has established a field scientific research observation system, including over 20 river observation sections and points, extending from alpine wetlands, glaciers and watershed water cycle, water ecology and water environment evolution, to river channel evolution, water and sand changes.
The expedition is still ongoing, with team members carrying out in-depth investigations and research in the headwater region, while always adhering to the concept of "the protection of the Yangtze River starts from its source."
"In the future, we will conduct interdisciplinary and cross-field cooperation with more scientific research institutions, and provide more scientific support for the protection of the Yangtze River by continuously accumulating discoveries and basic data," Xu said.
(Video reporters: Shi Weiyan, Du Xiaowei, Tian Zhongquan, Wu Zhizun, Chen Jie; Video editors: Wang Han, Li Qin, Zak Zuzanna, Wei Yin, Zhang Yichi.) ■
