As a key part of the Qinghai-Tibet Plateau ecosystem, the sources of the Yangtze and Lancang rivers are sensitive to climate change and the fragile ecological environment. They have an important impact on the stability of the climate system, water security, biodiversity and ecosystems.

In the Yushu Tibetan autonomous prefecture, Qinghai province, the Changjiang River Scientific Research Institute, led by the Changjiang Water Resources Commission of the Ministry of Water Resources, launched the 2022 comprehensive scientific expedition to the sources of the rivers. The scope of this expedition is the Tuotuo River, the source of the Yangtze River, the Dangqu River in the south, the Chumar River in the north, and the source area of the Lancanag River. This scientific expedition will conduct fixed-point "physical examinations" in the source regions, including the observation of ice storage and wetland carbon storage.

The river source research will face climate and geographical challenges, including low oxygen levels. Roads are rudimentary and the expedition team members will work at an altitude of more than 4,000 meters. The route covers the two source water systems of the Yangtze and the Lancang rivers.

This scientific expedition takes glacial water lakes as the starting point to explore the relationship between glacial changes and lake water volume. Glaciers store a large amount of water and are one of the supply sources for many rivers and lakes. In particular, once the glaciers reach the "inflection point" of melting, their shrinking will be irreversible, resulting in the reduction of water inflows from rivers and lakes, which in turn brings grassland desertification, soil erosion and other ecological problems. Only by the gathering and observation of basic data can scientific countermeasures be adopted for the prevention and management of ecological risks in the source region.

They have to confirm whether the main water source of the plateau lakes is precipitation or glacial melt water; how the water cycle between ice, lake, stratum and atmosphere is carried out; what impact will glaciers and lake changes have on future climate change.

They will use ground-penetrating radar to observe the thickness of the glacier, and then combine the height and other data accumulated in the previous period to calculate the ice reserves and changes.

Monitoring equipment is constantly being upgraded. Hong Xiaofeng, deputy director of the Water Resources Management Research Office at the Changjiang River Scientific Research Institute, has participated in many glacier expeditions. "Take a 3D laser scanner as an example, its scanning radius is 6 kilometers, and its accuracy is in millimeters. By superimposing the measurement results of different time periods, changes in glacier movement can be analyzed," he says.

The source area is dotted with glaciers, snow-capped mountains, lakes and rivers, swamps and wetlands. "Climate change will have a profound impact on watershed runoff, sediment, biodiversity and water circulation systems," says Zhao Liangyuan, deputy director of the Institute of Water Environment at the Changjiang River Scientific Research Institute.

After many years of scientific examination, he has handed over a rich answer sheet. For the first time, the fish winter grounds in the river has been discovered in the source of the Yangtze River. The current status of the water environment and the temporal and spatial distribution of water quality of the main rivers and lakes in the source area are preliminarily mastered; the hydrochemical characteristics and controlling factors of the main rivers and lakes are revealed.

In recent years, global climate change superimposed on human activities has had a certain impact on the hydrochemical characteristics of major rivers in the source region, the water environment, and the distribution of aquatic organisms in rivers. The scientific research team adopted on-site investigations, online real-time monitoring and indoor monitoring. By combining analysis and data on water environment indicators such as nutrients, main ions, metal elements and organic matter, scientists will find out the distribution of aquatic organisms.

The scientific expedition team of the Changjiang River Scientific Research Institute conducts research in Zadoi county, Qinghai province, in the source area of the Lancang River. XIAO YIJIU/XINHUA