Sluice project to lift Poyang's water level

Updated: 2022- 05- 24

Draft assessment report says plan will 'do more good' after decadelong debate

A huge sluice gate project that would cut through Poyang Lake, China's largest freshwater lake, where it connects with the Yangtze River, is "very necessary" and will "do more good than harm", according to an official document.

Research for the project dates back more than a decade, when it was proposed by authorities of Jiangxi province, where the water body is located. Amid concerns about its environmental impact, the project is still going ahead.

In 2009, 15 experts, including some high-profile academicians, jointly wrote to then premier Wen Jiabao calling for the project to be halted considering its irrevocable impact on wetlands and endangered waterfowl.

In early 2021, however, the province's natural resources department made public a notice to solicit opinions for the project's preliminary examination and location. The department said the project has been listed as one of 150 major water conservancy projects the country plans to start building from 2020 to 2022.

On May 16, Jiangxi's department of water resources unveiled a draft environmental impact assessment for the 16.7 billion yuan ($2.5 billion) project, saying that the public can voice their opinions to the authority.

According to the draft document, which was compiled by the China Institute of Water Resources and Hydropower Research in Beijing, the project's 64 sluice gates, which combined stretch for nearly 2.4 kilometers, will open during the flood season from April to August.

They will close for the rest of the year to "relieve a series of water safety problems caused by the excessively fast decline of water levels and the excessively low water level" in the water body.

In recent years, Poyang Lake has frequently made headlines in the dry season when it had little or no water in many of its parts.

Frequent drought has greatly affected shipping and agricultural production in the region, which is a major rice producer.

Wang Hao, a water resources expert from the institute and an academician of the Chinese Academy of Engineering, said the low-water period of Poyang has been extended because some major upstream reservoirs, including the Three Gorges Reservoir, were built and started storing water.

The average water level in the lake from September to October between the years 2008 and 2018 dropped by about 1.8 meters, and the low-water period in the lake started 33 days earlier than previously on average, Wang told a webinar themed on the project last year.

He said his team's analysis shows that, with the long-term operation of the reservoir group upstream of the Poyang, the declining water level in the lake from September to October will become an "irreversible" norm.

"Without taking any measures, the trend will continue," he said.

A key concern of many conservationists is that the project may jeopardize the habitat of the highly endangered Yangtze finless porpoise. The lake is also a vital migration route and winter habitat for migratory birds.

"The construction of the project can offer a guarantee for the improvement of the habitats for wild animals," the report said.

It said the project is expected to result in a more favorable living environment for the Yangtze finless porpoise as it helps restore the water level of the lake in the dry season to what it was before 2003.

From September to October, with a larger area to seek food and lay eggs, the number of fish will rise and thus increase the availability of food for the mammal.

The lake area habitable for the porpoise will be larger from September to November, creating much better conditions for them to hunt. The risk of them being stranded and affected by human activities will become smaller.

But it is admitted that the operation of the project will bring some negative impact to the environment and ecosystem of the lake.

In the long run, with its hydrological condition restored, the current population and distribution range of plant species in the low-lying land of the lake may be subject to change, negatively impacting some migratory birds that currently winter in these areas, the document said.

"But this will not change the germplasm resources of plants and the diversity of species in Poyang's wetland," it said.

The project will not impose a marked effect on fish species in the lake, as the breeding migration of major fish species mainly happens from April to August when the sluice gates will be open, it said.

The project also includes some measures to facilitate fish going through the sluice gates, including fishways.

It will, however, further restrain the Yangtze finless porpoise from their migration activities. In the long term, it may change the distribution of the mammal in the part of the Yangtze downstream from the lake, "increasing the risk for survival of its group species in the Yangtze's main stem".

Source: China Daily