Xinhua Perspective | Climate Warming Brings Series of Changes to the Ecological Environment of the Yangtze River Source Area

Recently, reporters from Xinhua News Agency's "Xinhua Vision" participated in the 2023 comprehensive scientific research activity on the Yangtze River source, led by the Yangtze River Academy of Water Resources Commission of the Ministry of Water Resources. They found that in the context of global warming, the ecological environment of the Yangtze River source area in the hinterland of the Qinghai Tibet Plateau is undergoing a series of changes.

The Three Sources of the Yangtze River: The overall water quality is excellent, and a large amount of water resources are transported downstream

The reporter saw that in the three sources of the Yangtze River, the Tuotuo River in the Zhengyuan area is turbulent and has a yellowish color; Nanyuan Dangqu has abundant water and clear river water; The Chumar River in Beiyuan is slightly red, like the veins of the earth, flowing in the wide riverbed.

Zhao Liangyuan, Deputy Director of the Institute of Water Environment at the Yangtze River Academy of Sciences, introduced that the Tuotuo River is mainly supplied by glacial meltwater, and carries a large amount of sediment along the way during the flood season, which is relatively turbid; When the river is mainly supplied with precipitation, ice and snow melting water, and groundwater, it undergoes large-scale wetland regulation and filtration, resulting in clear river water; The Chumar River flows through iron rich rock layers and has a reddish tint.

"The three sources of water in the Yangtze River exhibit different characteristics, but the overall water quality is excellent," said Zhao Liangyuan.

The ecological environment status report of Qinghai Province shows that in recent years, the water quality in the source area of the Yangtze River has been maintained in excellent conditions ranging from Class I to Class II.

The rivers in the source area of the Yangtze River not only have good water quality, but also have a large water volume. According to the statistics of the Qinghai Provincial Department of Water Resources, from 2018 to 2022, the annual average total water resources transported by the Yangtze River from Qinghai to downstream reached 25.995 billion cubic meters. According to the 2022 National Economic and Social Development Statistics Bulletin of the National Bureau of Statistics, the per capita annual water consumption in China is 425 cubic meters, which is equivalent to the annual water consumption of over 61 million people.

The scientific expedition team told reporters that the source area of the Yangtze River is located in a high-altitude natural environment, with low runoff temperature and high flow velocity. There are fewer types and concentrations of pollutants such as organic matter and nutrients.

At the same time, the intensity of human activities in the source area of the Yangtze River is low, and the water environment quality is less affected by human activities. In addition, the country continues to strengthen the protection and restoration of the water ecological environment in this area, driving the continuous enhancement of water source conservation capacity and the continuous improvement of water ecological environment quality, providing sustainable and clean water for people below the source area of the Yangtze River.

River water system: increased runoff and riverbed oscillation pose challenges to the safety of road, bridge, and pipeline infrastructure

At the confluence of the Tuotuo River and Dangqu River, the Baoji Balong River, like a long hair Fried Dough Twists braid, was presented to the scientific research team. The river was wide and shallow, wandering and intertwined, with many sandbanks, many branches in parallel, and the widest part of the river was more than 3 kilometers.

Like Nangji Balong, the lower reaches of Tuotuo River, Chumar River, Dangqu River and its tributaries Buqu and Gaerqu, as well as the upper reaches of the Yangtze River flowing through the upper reaches of the Tianhe River, are mainly braided channels, with river water wandering in wide channels.

A braided river channel connecting the tributaries of the Tianhe River. Photo by Xinhua News Agency reporter Liu Shiping

"The large-scale braided water system is a prominent feature of the rivers in the source area of the Yangtze River," said Xu Ping, Chief Engineer of the Yangtze River Academy of Sciences.

The Qinghai Tibet Railway crosses the braided river channel of the Tuotuo River. Photo by Xinhua News Agency reporter Liu Shiping

It is reported that on the Qinghai Tibet Plateau, the riverbed at the source of the river is mostly frozen soil, making it difficult for the river water to erode downwards. In addition, there are no natural constraints formed by mountains on both sides, nor are water conservancy projects such as embankments and revetments built in plain areas. When the river flow in the source area of the Yangtze River is large and fast, the erosion of the river is mainly caused by lateral deformation, resulting in a constantly changing "braided" shape of the riverbed.

Zhimenda Hydrological Station guards the outlet of the main flow of the Tianhe River in the source area of the Yangtze River. According to the 2022 China River Sediment Bulletin released by the Ministry of Water Resources, the Zhimenda Hydrological Station recorded an annual average runoff of 16.7 billion cubic meters and an annual sediment transport of 12 million tons in the past 10 years, which were 24.6% and 20% higher than the multi-year average values from 1967 to 2000, respectively. This indicates a significant increase in the overall runoff and sediment concentration of the Yangtze River source area.

Not long ago, the section of the Tongtian River directly leading to the river was hit by a catastrophic flood, with some roads severely damaged by the flood. Some sections of the road were subject to traffic control and herdsmen were relocated and resettled.

Zhou Yinjun, Deputy Director of the Institute of Rivers at the Yangtze River Academy of Sciences, stated that when there is a significant increase in runoff and sediment transport in the braided river channels in the source area of the Yangtze River, the braided strength and lateral expansion of the river continue to strengthen, which will pose a certain threat to the safety of infrastructure such as roads, bridges, oil and communication pipelines near the riverbed.

Alpine grassland: verdant and vibrant, rapidly warming up or causing grassland degradation

The reporter was traveling in the source area of the Yangtze River, with an average altitude of over 4500 meters, and saw many places with lush vegetation, lush grass, and herds of cattle and sheep, presenting a vibrant plateau ecological landscape.

Dr. Ren Feipeng, a scientific research team member from the Yangtze River Academy of Sciences, told reporters that on-site investigations have shown that the vegetation in the alpine meadows widely distributed in the source area of the Yangtze River is dominated by cold and drought resistant sedge plants such as high-altitude Kobresia and dwarf Kobresia. The plants are usually relatively short, mostly less than 20 millimeters.

In order to adapt to extreme living environments such as low temperatures, drought, poor soil, and strong winds on the plateau, many plants in the source area of the Yangtze River exhibit a dense arrangement and close to ground growth, resembling "huddling together for warmth". This low and dwarf morphological feature not only enhances the adaptability of plants to extreme climate and nutrient conditions, but also enhances their ability to resist lodging.

In 2023, Zhang Shuangyin, a member of the Jiangyuan Comprehensive Scientific Expedition Team, collected soil samples from Dangqu Wetland for calculating soil carbon content. Photo by Xinhua News Agency reporter Li Jinfeng

Affected by global climate change, the temperature in the source area of the Yangtze River has increased in recent years, resulting in increased precipitation. The 2022 National Ecological Meteorological Bulletin released by the China Meteorological Administration shows that the three river source areas, including the Yangtze River, saw an average increase in precipitation of 30 millimeters every 10 years from 2000 to 2022, and an average increase in annual temperature of 0.4 degrees Celsius every 10 years. During this period, 91.2% of the vegetation ecological quality in the Three Rivers Source area improved.

At the same time, the changes in the alpine grassland ecosystem during the rapid warming process have attracted the attention of scientific research team members. Research has shown that sustained warming beyond the critical point may disrupt the balance of the original ecosystem, leading to vegetation degradation, a decrease in grassland animal productivity, and a decrease in ecological environment quality.

Ren Feipeng and his teammate Sun Baoyang have been continuously conducting "simulated warming experiments on alpine grassland ecosystems" in the source area of the Yangtze River in recent years. Research has found that when the warming amplitude reaches or exceeds 3 degrees Celsius, the alpine grassland ecosystem undergoes significant changes.

"A small increase in temperature significantly promotes the improvement of plant productivity. However, when the temperature exceeds a certain critical value, there are significant changes in grassland biodiversity and species density." Ren Feipeng said, "In the future, further observation is needed to improve the early warning ability of ecosystem degradation risks.".

Wildlife: The number continues to increase, and some areas are facing "human bear conflicts"

At the foot of the Gangjiaquba Glacier at an altitude of over 5200 meters, scientific expedition team member Liu Han waded into the cold river water melted by the glacier to collect samples of aquatic organisms. In no time, he harvested a sample of plateau loach with a body length of about 5 centimeters.

In recent years, scientific research team members have delved into the rarely visited three sources of the Yangtze River, initiated research and protection of fish habitats in the Yangtze River source, gradually uncovering the overwintering and breeding mechanisms of key fish species such as the small headed naked croaker. In the southern source of the Yangtze River, the sixth species of fish, the Siji plateau loach, has been recorded.

The ecological environment in the source area of the Yangtze River continues to improve, with not only a significant increase in the number of aquatic species such as fish, but also thanks to the protection of the government and the people, as well as some herdsmen setting down their grazing whips to become ecological caretakers. Rare wild animals such as snow leopards, Tibetan antelopes, wild yaks, and Tibetan wild donkeys have also significantly increased.

During the scientific expedition, the reporter occasionally encountered scenes of Tibetan wild donkeys leisurely strolling, Tibetan antelopes chasing and playing, and occasionally saw wolf packs hunting Tibetan wild donkeys and other life and death duels.

On May 29th, in Kekexili, Qinghai, a group of female Tibetan antelopes waiting to give birth crossed the Qinghai Tibet Highway and headed towards Zhuonai Lake. Photo by Xinhua News Agency reporter Zhang Hongxiang

Zhao Xinquan, an expert who has long been engaged in research on the ecology of the Three Rivers Source and high-altitude agriculture and animal husbandry, introduced that in recent years, the habitat environment of wild animals on the Qinghai Tibet Plateau has significantly improved, and the population of key species has increased by 2 to 3 times compared to 20 years ago. The number of Tibetan antelopes has increased from less than 20000 in the early protection period to nearly 70000, and the number of Tibetan wild donkeys has recovered to 36000.

The reporter learned that with the increasing efforts to protect rare wildlife, the number of brown bears in some areas has sharply increased. In some remote areas, brown bears have broken into herdsmen's homes, damaged their property, and posed a great threat to personal safety. June to August is the peak period for brown bear accidents. Experts and local governments are conducting in-depth investigations into the existing "bear disease" problem and exploring feasible solutions.