Devoured: How China’s Poyang lake was decimated by dredging and sand mining

Devoured

How China’s largest freshwater lake was decimated by sand mining.

Dredging ships have sucked

millions of tonnes of sand from the bed and shores of Poyang lake, drastically altering its ability to function.

New plans to build a 3km sluice gate now further threaten the delicate

ecosystem.

Here’s how the lake has been scraped, scarred, and left

fragile.

Devoured

How China’s largest freshwater lake was decimated by sand mining.

Dredging ships have sucked millions of tonnes of sand from the bed and shores of Poyang lake, drastically altering its ability to function.

New plans to build a 3km sluice gate now further threaten the delicate ecosystem.

Here’s how the lake has been scraped, scarred, and left fragile.

Devoured

How China’s largest freshwater lake was decimated by sand mining.

Dredging ships have sucked millions of tonnes of sand from the bed and shores of Poyang lake, drastically altering its ability to function.

New plans to build a 3km sluice gate now further threaten the delicate ecosystem.

Here’s how the lake has been scraped, scarred, and left fragile.

Devoured

How China’s largest freshwater lake was decimated by sand mining.

Dredging ships have sucked millions of tonnes of sand from the bed and shores of Poyang lake, drastically altering its ability to function.

New plans to build a 3km sluice gate now further threaten the delicate

ecosystem.

Here’s how the lake has been scraped, scarred, and left fragile.

Devoured

How China’s largest freshwater lake was decimated by sand mining.

Dredging ships have sucked millions of tonnes of sand from the bed and shores of Poyang lake, drastically altering its ability to function.

New plans to build a 3km sluice gate now further threaten the delicate ecosystem.

Here’s how the lake has been scraped, scarred, and left fragile.

Satellite image taken Dec. 21, 2017. ©2021 Maxar Technologies / produced by Earthrise

Decades of mass urbanisation in China have fuelled rampant demand for sand to make glass, concrete and other materials used in construction. The most desirable sand for this industry comes from rivers and lakes rather than deserts and oceans. Much of the sand used to build the country’s megacities has come from Poyang Lake, in the eastern province of Jiangxi.

Already ravaged by sand mining, the lake now faces a biodiversity crisis. At the start of this year, the provincial government revived a project to alleviate drought by regulating water flows between the Yangtze River and Poyang Lake with a 3 km-long sluice gate.

Chinese conservationist Zhang Daqian criticized the planned structure, saying it would cut the lake off from the river, “leaving Poyang a dead lake”.

The shallow lake, a national nature reserve, is also a rest stop for over 300 species of migratory birds, including the critically endangered Siberian crane. It is home to the endangered Yangtze River or finless porpoise, a short-snouted dolphin-like creature known for its ‘smile’ but of which there are only around 1,000 individuals left.

CHINA

Hefei

Shanghai

Wuhan

Ningbo

Poyang

Lake

Nanchang

Hefei

CHINA

Shanghai

Wuhan

Ningbo

Poyang

Lake

Nanchang

Changsha

Hefei

CHINA

Shanghai

Wuhan

Ningbo

Poyang

Lake

Nanchang

Changsha

CHINA

Hefei

Shanghai

Wuhan

Ningbo

Poyang

Lake

Nanchang

Poyang Lake is a key flood outlet for the Yangtze River, which overflows during summer and can cause extensive damage to crops and property. In winter, the lake’s water flows back out into the river.

Sand mining in the main river and its tributaries and lakes is believed to be responsible for the abnormally low water levels during winters over the past two decades. It also has made it harder for authorities to control the summertime water flow. In March, the government moved to restrict sand mining activities in some areas and arrested illegal miners, but it stopped short of an outright ban on sand mining.

During a visit to Poyang Lake in June, a Reuters reporter saw several barges piled high with sand floating just off the lake’s western bank, waiting to be unloaded at a nearby port. A sand dredger idled nearby. Local residents said activity had been scaled back, indicating the new policy against illegal sand mining was having an effect.

Sand barges are seen on Poyang Lake on June 23, 2021. REUTERS/Gabriel Crossley

David Shankman, a geographer at the University of Alabama who has studied the lake extensively, said the wintertime water level declines are “the result of extensive sand mining that began in 2001”.

The lake’s surface level reached an all-time high in summer 2020 at 22.7 meters, just months after hitting a 60-year low of about 8 meters during the winter of 2019, according to NASA satellite data.

"Sand mining resulted in erosion of the lake’s outlet channel,” Shankman said. “The larger channel accelerated lake drainage into the Yangtze River and lowered water levels more than would otherwise have occurred.”

Low water levels leave farmers with less water for irrigation, while also shrinking habitat for birds and fish.

President Xi Jinping once described Poyang Lake as a vital “kidney” filtering the country’s water supplies. Today, it looks very different from two decades ago.

Jan. 1997

Smooth

sand banks

Dec. 2019

Missing

sand

Town

Industrial

structures

Gouged

shore lines

Large sand

banks gone

Jan. 1997

Dec. 2019

2 km

Smooth

sand banks

Missing

sand

Town

Industrial

structures

Gouged

shoreline

Large sand

banks gone

Jan. 1997

Dec. 2019

2 km

Smooth

sand banks

Missing

sand

Town

Industrial

structures

Gouged

shore lines

Large sand

banks gone

Jan. 1997

Smooth

sand banks

Dec. 2019

Missing

sand

Town

Industrial

structures

Gouged

shore lines

Large sand

banks gone

2 km

Jan. 1997

Dec. 2019

Smooth

sand banks

Missing

sand

Town

Industrial

structures

Gouged

shore lines

Large sand

banks gone

Satellite images taken Jan. 10, 1997 and Dec. 9, 2019. NASA, Landsat

Reuters worked with Earthrise Media, a non-profit group that analyzes satellite imagery, to map changes in the lake’s shoreline since 1997, giving an indication of how much coastal sand has been removed. “The water levels in the lake vary dramatically between wet and dry seasons,” said Edward Boyda, co-founder of Earthrise.

“By looking at times of low water, we see the areas - miles across - where the dredging has cut channels and pits in the lake bed and resculpted the shores of the lake,” he said.

The analysis reveals that the surface area of the northern part of the lake, shown in the map below, has expanded around 70% from 96 sq km (37 sq miles) in 1997 to 164 sq km (63 sq miles) in 2019, when comparing similar times of year.

Change in shape of the lake

Map shows surface water area in 2019 compared with 1997

Old shape

Jan. 1997

New lake area

Dec. 2019

Swathes of

sandy shoreline

now gone

Large sand peninsula

mostly removed

Change in shape of the lake

Map shows surface water area in 2019 compared with 1997

Old shape

Jan. 1997

New lake area

Dec. 2019

Swathes of sandy

shoreline gone

Eroded

shoreline

Large sand peninsula

mostly removed

Change in shape of the lake

Map shows surface water area in 2019 compared with 1997

Old shape

Jan. 1997

New lake area

Dec. 2019

Swathes of

sandy shoreline

now gone

Large sand peninsula

mostly removed

A closer look at devastation

An extraordinary series of high-resolution images, taken in December 2017 and stitched together below, illustrates the intense sand mining activity seen on the lake during a single day.

Vast sand tracts have given way to water. The once-smooth banks through which water flowed easily have vanished, with the banks now jagged and pocketed.

Satellite image taken Dec. 21, 2017. ©2021 Maxar Technologies / produced by Earthrise

Under the surface

While changes in the lake’s shape at the surface can be tracked by satellites, monitoring what’s going on beneath the water can be more difficult. Dredgers can suck large amounts of sand from the lake bed, leaving craters and pits that don’t show up on images taken above the surface.

In 2014, researchers published ultrasound data measuring the changing profile of the lake’s bottom between 1998 and 2013. As sand mining took off in the area, the depth of the lake dropped drastically, according to illustrations of the data, published in the Journal of Hydrology.

Yangtze

Cross sections

shown below

Poyang

lake

Profile of the lake bed

Cross sections of the lake measured in 1998 and 2013 show how the shape has changed.

Note: water level of the lake can fluctuate.

1998

Missing sand

Lake

20 m

Sand

1 km

Lake

Sand

2 km

Sand

3 km

Yangtze

Cross sections

shown below

Poyang

lake

Profile of the lake bed

Cross sections of the lake measured in 1998 and 2013 show how the shape has changed.

Note: water level of the lake can fluctuate.

1998

Missing sand

Lake

20 m

Sand

1 km

Lake

Sand

2 km

Sand

3 km

Yangtze

Cross sections

shown below

Poyang

lake

Profile of the lake bed

Cross sections of the lake measured in 1998 and 2013 show how the shape has changed.

Note: water level of the lake can fluctuate.

1998

Missing sand

Lake

20 m

Sand

1 km

Lake

Sand

2 km

Sand

3 km

Yangtze

Cross sections

shown below

Poyang

lake

Profile of the lake bed

Cross sections of the lake measured in 1998 and 2013

show how the shape has changed.

Note: water level of the lake can fluctuate.

1998

Missing sand

Lake

20 m

Sand

1 km

Lake

Sand

2 km

Sand

3 km

Downstream

Sand mining activity is not entirely contained within the lake itself. The many tributaries that flow into Poyang, and ultimately into the Yangtze, are also a hive of mining activity. About 100 km south of the lake, the Gan River — one of the Yangtze’s principal tributaries — also appears in this July 19, 2018, image to be busy with sand mining.

Rows of enormous barges are lined up, likely ferrying sand from nearby mining sites in Poyang Lake, the Gan River or possibly elsewhere. The buildings on shore give a sense of scale of these large ships.

Rows of barges are seen on the Gan River next to the village of Yanjiang on July 19, 2018. Satellite image: Google, ©2021 Maxar Technologies

Further down the Gan River on the same date, more ships can be seen, along with dredging vessels extracting sand. The image shows a 4-km stretch of river buzzing with sand mining activity. The nearby villages provide a sense of scale.

Gan River

South of Poyang Lake - July 19, 2018

Barges full

of sand

heading

south

Scarred

coastline

Passing

aircraft

Barges full

of sand

Dredgers

Dredger

Sand mining

Dredger

Sand transferred

between ships

Dredger

N

100m

Gan River

South of Poyang Lake - July 19, 2018

Barges full of sand

heading south

Scarred

coastline

Passing aircraft

Barges full

of sand

Sand dredgers

Dredger

Sand mining

Dredger

Sand transferred

between ships

Dredger

N

100m

LG

Gan River

South of Poyang Lake - July 19, 2018

Barges full of sand

heading south

Scarred

coastline

Passing aircraft

Barges full

of sand

Sand dredgers

Dredger

Sand mining

Dredger

Sand transferred

between ships

Dredger

N

100m

Gan River

South of Poyang Lake - July 19, 2018

Barges full of sand

heading south

Scarred

coastline

Passing

aircraft

Barges full

of sand

Dredgers

Dredger

Sand mining

Dredger

Dredger

N

100m

Rows of barges are seen near sand mining activity on the Gan River, July 19, 2018. Satellite image: Google, ©2021 Maxar Technologies

Environmental impact

By dredging and extracting sand and gravel from the lake, miners are disturbing the lake bed and its wildlife. Fish become disoriented as stirred-up sands cloud the waters and plants are uprooted. Ships and machinery fill the area with noise. Sand left heaped in piles waiting for collection creates obstacles for animals like the finless porpoise.

Adding a sluice gate to regulate the water flow would disrupt the natural ebb and flow between Poyang and the Yangtze, potentially threatening tidal flats that serve as feeding stops for migratory birds. Losing that natural water circulation could also hurt Poyang’s ability to flush out nutrients, raising the risk that algae could build up and disrupt the food chain.

Drone footage shows Poyang’s vast stretches of jagged shoreline followed by activity at a sand mining site. Dec. 20, 2019. REUTERS

“We need to realize the lack of water in Poyang Lake can’t be fixed by building more sluice gates,” said Zhang Daqian, a conservationist at the China Biodiversity and Green Development Fund.

“It’s best to study the effects before building a gate as a quick fix, which could bring more problems than benefits,” he said.

By

Simon Scarr and Manas Sharma

Additional reporting by

Gabriel Crossley and David Stanway

Editing by

Kanupriya Kapoor, Katy Daigle and Christian Schmollinger

Sources

Earthrise Media; NASA; Journal of Hydrology, Sand mining and increasing Poyang Lake’s discharge ability: A reassessment of causes for lake decline in China: Xijin Lai, David Shankman, Claire Huber, Herve Yesou, Qun Huang, Jiahu Jiang