Analysis: Evidence that Three Gorges dam hit dangerous water levels before
Satellite analysis reveals that water levels of the Chinese Three Gorges Dam exceeded alarming water levels in the past.
A remote sensing analysis found that in late 2018 and 2019, water levels of the Three Gorges dam reservoir has climbed to dangerous water levels. The findings emerged after years of claims by supporters that climate change has no or minimal effect on the basin and its people.
The Chinese Three Gorges dam is the world’s largest power station by the measure of installed capacity, and is hailed as an engineering marvel by its proponents. Hydropower became and remains China’s largest renewable source and hit a total of 352 GW in hydro capacity by the end of 2018, the year when the country celebrated its 40th anniversary of its historic economic reform programme (see chart).
Last week, reported water levels at the dam’s reservoir surged almost 20 metres higher than the official warning level. Now, findings from a satellite analysis suggests that alarming water levels occurred before, and previous interventions may have failed.
Analysts at satellite imagery firm SpaceKnow argue that water levels appeared stable in August and are now slightly decreasing. This is in-line with findings by the Changjiang Water Resources Commission, which announced that water levels began receding last Saturday.
Water levels only decreased after hitting 167.65 metres, which the Changjiang Water Resources Commission titled as “the highest [water level] since the reservoir was built in 2003”.
Investigator found evidence that past levels may have even been higher before. When checking open-source Sentinel 2 satellite data and found confirmation that previous levels may have exceeded that. Satellite images for December 22, 2019, compared with those from August 13 and August 23, showed that previous water levels topped recent ones. “[Water levels] are nowhere near the values we have observed in December 2018 and 2019”, a representative at SpaceKnow said.
The investigation was handed information that Three Gorges Dam was operated with “a very high-water level due to the continuous rainfall — 100-year return period — upstream, especially in Mingjiang River Basin”. The source represents a colleague of a critical water resources management researcher who works at the University of Wisconsin-Madison.
The source adds that as well as the Three Gorges, other upstream dams including the Xiluodu and Xiangjiaba, are used to impound the reservoir inflow to mitigate the downstream flood risk.
As the Three Gorges Dam is so important for flood control and power generation in the Yangze River Basin, it is protected by the Chinese Government: “Its operators are not allowed to share any details about its operation”, the source revealed. The statements made by the source could not be verified.
At the end of July, China recorded a devastating death toll after the worst torrential rains ‘in decades’ hit the country, according to several news reports. Cities in the central region along the Yangtze River were flooded in July due to monsoon season rainfalls. It was the worst flooding since 1998, with at least 141 people dead or missing.
Critics of the dam use the latest spate of floods as evidence that the Chinese dam project failed to help control the risk of flooding, casting doubt on its benefits. The dam was completed and became fully functioning in 2012. Chinese water conservation experts quoted by The Global Times, an English-language Chinese tabloid propaganda paper, wrote that the Three Gorges dam, together with other dams, would help “disperse flood control pressure to prevent a super-large flood peak from causing a catastrophe for cities along the river”.
In 2019, the newspaper published an exposé that tried to disprove false claims about the dam, but failed to mention alleged impacts of climate change and flood risk. It did mention claims that the dam changes the ecological environment, which it admitted is true.
Several studies and experts raised concerns that the region’s weather could suffer under climate change. Weather conditions, especially with a huge lake influencing the local climate, could become more volatile and thus affect the dam via heavy rain.
Chinese studies largely dispute that climate change plays a significant role. One study published by the Social Sciences Academic Press in 2011 under the Chinese Academy of Social Sciences, said the dam’s environmental impact “was limited to a 12-mile radius and there was no direct link between the dam and local severe droughts and floods in recent years”.
Nonetheless, China’s Meteorological Administration seems increasingly worried. In a 2015 statement, Zheng Guoguang, the administration head, said the uptick in recent weather disasters such as floods, typhoons, droughts and heatwaves bore a toll due to climate change and catastrophes were a threat to projects like the Three Gorges Dam.
Proponents of the dam indicate that the country is heading in the right direction, with new draft legislation announced in the beginning of the year. It is to protect the Yangtze River, its ecological environment and to help green development.
Previously, the dam has been criticised for contributing to destruction to archaeological and cultural sites, and to help displacement of large numbers of people. Others said there is now an increased landslide risk — in 2014, a landslide on the Yangtze wiped out one of the Three Gorges hydropower stations and geological experts have identified 5,000 danger points for collapses, landslides, dangerous cliffs and banks. Academic studies found evidence of the dam’s impact on the ecological environment.
With its 22.5 GW capacity, the Three Gorges Dam accounts for more than four times the size of Africa’s largest and soon-to-be launched hydroelectric dam project, the GERD in Ethiopia. Three Gorges Dam is the largest contributor to China’s hydropower capacity (see chart).
