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NTU researchers to help mining companies source sand sustainably in South-east Asia

2024-01-28 00:00:00.0 海峡时报-新加坡原网页

SINGAPORE – To reduce the ecological impact of sand extraction in South-east Asia, researchers in Singapore have come up with a way to monitor the scale of sand mining, so it can be done sustainably.

Scientists from Nanyang Technological University have developed the first monitoring system that quantifies the exact scale and extent of illegal sand mining, starting with the Mekong Delta.

The delta, primarily in southern Vietnam, is continually shaped as the vast network of Mekong River waterways leading to the South China Sea deposit sediment that form fertile land banks.

But the area is facing the fallout of intense sand extraction over the years.

Using publicly available satellite data, the monitoring system zooms in on sand mining ships and correlates this data with measurements of how much the riverbed has sunk during an initial field survey by the NTU team, which is a relatively low-cost method compared with on-site surveillance of the whole delta region.

The researchers found that around 53 million cubic metres of sand had been extracted from the Vietnamese Mekong Delta in 2022 – more than double the amount of around 20 million cu m declared by mining companies.

“We were also able to determine the locations where the available supply of sand is less than the amount being mined, which essentially causes the riverbank to sink and eventually collapse,” said Assistant Professor Edward Park, who led the research project.

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“The monitoring system was designed to be low-cost and to track sand mining regularly, so that it could be used by the Vietnamese authorities to quickly detect the presence of illegal sand mining and roll out the required enforcement measures,” he told The Straits Times.

With sand being stripped from its riverbed, coastal and riverbank erosion is rampant in the Mekong Delta, causing homes to crumble and livelihoods – from fishing to farming – to disappear.

Sediment plumes from dredging can suffocate fishes, while increasingly cloudy waters could prevent sunlight from entering the water, reducing the rate of photosynthesis by aquatic plants and hence the amount of dissolved oxygen in the river vital for aquatic life, said Dr Park.

The Mekong is the “rice bowl” of Vietnam, but as the riverbed sinks and water levels fall, so does the occurrence of natural flooding crucial for irrigating the many agricultural fields in the delta.

River sand tends to be coarser and more angular, and is crucial for construction projects, whereas sea sand has finer grains like powder, and is typically needed for land reclamation works.

Vietnam banned exports of sand in all forms in 2017 to meet its high domestic demand. But the amount of sand dredged still puts a strain on the available supply.