Considering the data recorded over the past few decades at many measuring stations combined with satellite images, scientists found that the water level on the Yangtze River, China has decreased by about 2cm every 5 years since 1980.
While this 2cm loss is small, the researchers warn that overall, the event could have major environmental and economic impacts.
According to the South China Morning Post, in a study published in the February issue of Advances in Water Science , author Nie Ning and colleagues at the Chinese Ministry of Education suggested that the lower water level of the Yangtze River is mainly due to the low water level of the Yangtze River. due to climate change and human impacts such as changing the landscape, building hydroelectric dams, etc.
The water level on the Yangtze River has decreased by about 2cm every 5 years since 1980.
About 460 million people live along the Yangtze River, of which the main economic pillar is the city of Shanghai. Due to increased industrial activity, more than 1,000 riverside lakes have been filled. Previously, scientists assumed that the total amount of water in the river remained unchanged, but new research suggests otherwise.
To come up with an approximate estimate, Nie’s team combined data from ground-based monitoring stations with satellite images that can detect changes in gravity caused by water.
They concluded that climate change , which results in unusual climate events such as heat, reduces the amount of rain that flows into the Yangtze River.
Warmer temperatures also widen the high/low water levels of the river, causing more floods and droughts. The amount of water evaporation also increased, partly due to high temperatures, partly due to human impact in large cities.
The role of hydroelectric dams, according to the researchers, is to have a relatively small negative impact on water availability. The operation of 15 large hydroelectric dams, including the Three Gorges Dam, causes river levels to drop in winter and spring and rise in the remaining warm months.
Xie Zhicai, a researcher with the Institute of Aquatics at the Wuhan Academy of Sciences (who was not part of the research team), said the drop in river levels could cause unexpected impacts on the environment. For example, concentrations of pollutants in river water can increase and harm vulnerable aquatic species.
Less water also means hydroelectric dams have a greater role to play in regulating water, disrupting natural cycles. Some fish species, including sturgeon – which are very sensitive to changes in temperature and water levels – will be affected. Specifically, their reproductive activity can be disrupted.
The report confirms that, at present, the Yangtze River is not short of water, the level of decline is still low, but negative impacts may occur in the long run.
An anonymous scientist told the South China Morning Post that reducing water levels on the Yangtze River could be more harmful than the report indicates.
Now, every day, an undisclosed large amount of water is regularly taken from the Yangtze River to be carried northward, 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 this anonymous researcher, it seems that the Chinese government is also aware of the impact of reducing water levels on the river, so it has tightened new construction projects along the Yangtze River. From January 2021, all fishing in the river is also banned for 10 years to protect the river from overfishing and pollution.