In Vietnam, the mighty Mekong's banks are crumbling as illegal sand miners run riot

When the retaining wall of Vietnamese fish farmer Ho Thi Bich Tuyen's catfish pond collapsed into the Hau River several years ago, she knew who was to blame: illegal sand miners.

"They took the sand, and the riverbed just kept going lower and lower," she said. "There were so many of them. The sand miners came close to the riverbank. So I told the local ward officials to shoo them away, but at night they came back again."

The damage caused 150 tonnes of Tuyen's catfish to escape into the wider Mekong Delta that were worth several billion dong (hundred of thousands of US dollars).

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"Because they took the sand, the erosion was so aggressive," said the 40-year-old owner of a fish farm in Can Tho, the largest city in the delta region.

Sand mining is eating away at the foundations of the Mekong Delta, with a report last month from Vietnam's Department of Climate Change and France's government-run French Development Agency finding that the practice had done more to alter sediment flows in the river than even hydropower dams - many of which are in China and have been blamed for worsening droughts downstream. Many researchers have also warned about sediment being trapped upstream and in tributary dams.

Ha Huy Anh, a national project manager at conservation body WWF Vietnam who co-authored part of the report that features this finding, said sand mining had also lowered the level of the riverbed and decreased the amount of groundwater residents are able to extract for household and farming needs.

"It was thought that climate change was the main driver [of threats to the delta]," he said. "But in the last decade, scientists have acknowledged the role of sediments and unsustainable sand mining - and upstream dams - as the greater threats to the delta."

River sand is preferred for construction in cities like Phnom Penh, Can Tho and Ho Chi Minh City because it can be extracted cheaply from nearby river channels, is easily transported by barge and has grains that are well sorted by size, according to the report.

But advocates and researchers are calling for more sustainable alternatives to be found, as the environmental impact of sand mining becomes clearer and Vietnam's quest for more infrastructure to support its economic development shows few signs of stopping.

To understand the state of sand in the delta, scientists have to rely on peer-reviewed academic papers and data from the Mekong River Commission. This shows that the delta is suffering a net loss of between 27.5-39.5 million tonnes of sand each year, as more is extracted from the river bed than can be replaced through natural processes - such as the flow of sediment from the upper Mekong.

Monitoring the exact state of sand in the delta is near-impossible without a comprehensive, unified data source, Huy Anh said, which is why WWF Vietnam is working with the country's Disaster Management Authority, supported by the German government, to develop a "sand budget" for the Mekong Delta.

The project aims to provide better visibility of sand movements in the delta, as well as monitoring mining activity and quantifying how much sand is being stored on the riverbed, by using technical tools such as sonar surveys and satellite analysis.

Illegal sand mining has been linked to tragedies such as bridge collapses in India, according to a report last year from the South Asia Network on Dams, Rivers and People.

In Vietnam, independent biodiversity specialist Nguyen Huu Thien fears for the future of major crossings such as My Thuan bridge in Vinh Long province, whose foundations appear to be at risk.

He pointed to nearby Minh islet, which crumbled into the river earlier this month as it "eroded devastatingly, [leaving] 4.1 hectares of land gone within hours, meaning the riverbed is empty". Dozens of people lost their homes and farmland in the incident.

Yet sand barges are still a common sight in the Mekong Delta. Speaking at a sand management conference in Can Tho city on Monday last week co-organised by WWF Vietnam, Duong Van Ni, a lecturer in Can Tho University's faculty of the environment and natural resources, compares the Mekong Delta to a living animal and its sediments to the body parts. "Sand is the legs of the delta. [By extracting it] we chop off our legs, so in the future even when we grow strong we won't have legs to walk on," he said.

On Facebook, numerous Vietnamese language groups proliferate offering river sand for sale at bargain basement prices - providing prospective customers with phone numbers, but no company names or receipts.

One Facebook seller offered This Week in Asia sand without a receipt that had been extracted from a river in An Giang province, where local authorities have reported businesses selling and transporting illegally sourced sand without receipts or permits.

Part of the problem is a lack of oversight from under-resourced environmental watchdogs. WWF Vietnam's Huy Anh said the delta provinces' environment and natural resources departments lacked the equipment, such as camera drones, to monitor sand mining and "only have one or two officials tasked with overseeing natural resources, while they also do other tasks".

Rampant, poorly regulated sand dredging has caused problems elsewhere in the Mekong region. A Nanyang Technological University study published last year found that extensive riverbed mining in Cambodia was to blame for a decreasing water levels in Tonle Sap, Southeast Asia's largest freshwater lake.

Back in Vietnam, fish farmer Tuyen said she hadn't seen sand miners near her farm for years, but she has been left to deal with the consequences of their actions.

After erosion caused one riverbank bordering her farm to "just vanish", Tuyen said she set about shoring up what was left - hiring workers to build four layers of new defences comprising: two rows of underwater plants; a wall made of sandbags filled with dirt and topped with concrete blocks; and an underwater steel fence for the innermost layer to keep her catfish under control.

"I'm holding onto this bank, otherwise [if] it erodes, there will be no road for me to use to deliver my fish," she said, adding that as hers was a family business she was "doing this for my parents".

This article originally appeared on the South China Morning Post (SCMP).

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