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The water level in the Yangtze has decreased by about 2 cm every 5 years since 1980
Although this 2 cm reduction is small, the researchers warn that overall, the incident could have significant environmental and economic impacts.
According to the newspaper South China morning post, in journal research Advances in water science February 2021, author Nie Ning and his colleagues from the Ministry of Education said that the lower water level of the Yangtze River is mainly due to climate change and human impacts, such as changes in the landscape, construction of hydroelectric dams …
About 460 million people live along the Yangtze River, whose main economic pillar is the city of Shanghai. Due to the increase in industrial activity, More than 1,000 riparian lakes were filled. Previously, scientists thought that the total amount of water in the river had not changed, but new research shows otherwise.
To give a rough estimate, Nie’s team combined data from ground monitoring stations with satellite images that could detect the change in gravity caused by the water.
They conclude that climate change as a result of unusual weather events such as heat reduces the amount of rain that falls on the Yangtze River.
Warmer temperatures also widen the river’s high / low water levels, causing more floods and droughts. The amount of water that evaporates has also increased, partly due to high temperatures and partly due to human impacts in large cities.
The role of hydroelectric dams is, according to the researchers, to have a relatively small negative impact on the amount of water. The operation of 15 large hydroelectric dams, including the Tam Hiep dam, causes the river’s water levels to drop in winter and spring and rise in the remaining warm months.
Xie Zhicai, a researcher at the Institute of Aquatic Resources of the Wuhan Academy of Sciences (who is not part of the research group), said that a drop in the river’s water level could have unexpected effects on the environment. For example, concentrations of pollutants in river water can increase and harm vulnerable aquatic species.
Less water also means that hydroelectric dams play a bigger role in regulating water, altering natural cycles. Some species of fish, including sturgeon, which are very sensitive to changes in temperature and water level, will be affected. Specifically, their reproductive activity can be reversed.
The report confirms that, at present, the Yangtze River is not lacking in water, the level decline is still low, but long-term negative impacts are likely.
An anonymous scientist shared with the newspaper. South China morning post that lowering the water level in the Yangtze could cause more damage than the report points out.
Now, every day, a large amount of water that is not constantly disclosed is carried north from the Yangtze River to arid cities, including Beijing.
According to the local government, more than half of the water consumed in Beijing comes from the Yangtze River.
According to the anonymous researcher, it appears that the Chinese authorities were also aware of the effects of the lowering of the water level in the river, which is why they tightened up new construction projects along the Yangtze River. From January 1, 2021, all river fishing activities were also banned for 10 years to protect the river from overfishing and pollution.
