Dashcam footage captured the moment a steel and concrete bridge collapsed, taking a truck and a motorcyclist with it.

Those who fell to their deaths on the Phong Chau Bridge near the northern city of Hanoi were among the hundreds killed by Typhoon Yagi.

And while the storm dealt the final blow to the bridge, it may not have been the only thing responsible for the tragedy.

Because there is a very valuable but often overlooked commodity in the Kızılırmak Delta.

And the insatiable demand for this substance is endangering communities and livelihoods.

Huge industry you’ve probably never heard of

Sand and aggregates such as gravel are some of the most important resources in the world.

They are used to produce a dizzying range of products, from cement and building materials to glass and fiber optics.

An estimated 50 billion tons are consumed each year; This equates to approximately 18 kilograms every day for every person on the planet.

This makes it the most mined resource in the world, according to Newcastle University sand mining researcher Chris Hackney.

“It’s used in just about everything,” he said.

Demand has increased rapidly in Vietnam in recent years as the country needs construction materials to fuel rapid urbanization.

And while more and more sand is being extracted from the Mekong delta in the south and the Red River in the north, massive hydropower schemes are blocking the natural flow of sediment that would normally help replenish the resource.

“We are using more than the river can provide,” Dr Hackney said.

“As a result, the morphology, shape and behavior of the river begins to change.”

Did sand mining cause the bridge to collapse?

The threat sand mining poses to critical infrastructure can be seen just 12 kilometers away, at the Trung Ha Bridge over the adjacent Da River.

Photos published by Tuoi Tre News show the riverbed on which the bridge was built, but exposed the foundations, leaving the bridge vulnerable to extreme weather conditions.

Vietnamese authorities blamed sand mining for the erosion and banned the passage of heavy vehicles until further notice.

The government, which did not respond to ABC’s request for comment, is also reportedly investigating the cause of the Phong Chau collapse.

A preliminary report blamed Typhoon Yagi, and the Ministry of Transport told VN Express that the piers were strengthened in 2018 and treated for erosion in 2019.

Dr Hackney said it was difficult to determine the sole cause of the collapse but believed sand mining may have been a contributing factor.

“A major flood event, a major storm, brought in a lot of water and probably caused a lot of materials to wash away,” he said.

“But the gradual lowering of river beds probably prepared this system to respond to major storms in this way.”

Doomed bridges and crumbling communities

Elsewhere in the world, riverbed mining and violent storms have proven deadly.

It was decades of dredging and a series of floods that caused Portugal’s Hintze Ribeiro Bridge to collapse in 2001, killing 59 people.

The previous year, 22 people were injured when the Kaoping Bridge collapsed in Taiwan, largely due to dangerous foundations and nearby gravel mining.

Although denied by the state government, mining has also been blamed for numerous incidents across India, including the Mahad collapse in 2016.

And in China, illegal and legal mining has been so widespread along the Yangtze River that it has disrupted shipping routes, made droughts more likely and floods harder to control.

Severe erosion accelerated by sand mining in Vietnam is threatening the homes of half a million people in the Mekong Delta, according to a World Wildlife Fund report.

Dr Hackney said that as river beds deepened due to extraction, salt water from the ocean was flowing further inland.

“What is starting to impact the availability of drinking water is the availability of fresh water for agriculture and aquaculture, which are major livelihood sources, especially in the Red River Delta,” he said.

“So farmers are having to switch their crops to different varieties of rice that are more tolerant of salty water.”

Will the industry continue unabated?

The world’s insatiable demand for sand is unlikely to end. But in recent years, some jurisdictions are taking environmental impact more seriously and trying to crack down on illegal operations.

PhD student Hannah Runeckles has spent years studying the environmental impact of human activities on the Red River and said the size and complexity of river systems make them difficult to monitor.

“When you’re trying to track mining ships, it’s really difficult when you have such a large area, especially trying to see where they’re going.”

“So we’re trying to use high-resolution satellite imagery focused on the last six years to try to identify where we see sand mining hotspots.”

Ms Runeckles said some communities were wary of the industry because they did not see “any profitability or positive impact”.

“They perceived sand miners as outsiders, taking sand from their own region, their livelihood, and selling it to other places,” he said.

He hoped his research would help policymakers better manage human activities to protect riverside residents and their livelihoods.

“As a society, we need sand. It is the backbone of the modern world,” he said.

“So to say that all sand extraction, hydroelectric power or flood control should be stopped is inadvisable, implausible.

“So we really need to think about where sand mining activities are taking place.”