It’s a resource used in global construction and mined from rivers and coasts across the world. But the humble grain of sand is being depleted by increased and relentless mining.
New research published in the journal Nature Sustainability and led by academics at the University of Hull has shown excessive sand mining is causing river beds to lower, leading to riverbank instability and causing increased likelihood of dangerous river bank collapse, damaging infrastructure, housing and putting lives at risk, leading to experts calling for a global regulatory approach.
Researchers focused on the Mekong River – a 1km wide sand-bedded river in Southeast Asia.
Dr Chris Hackney of the University of Hull’s Energy and Environment Institute, who was lead author on the paper, said: “Sand is the most used resource on the planet, aside from water. When you start looking for it, it is everywhere. With the world currently undergoing rapid population growth and urbanisation, concrete production has grown massively, fuelling major demand for resources.
“Many of the world’s large sand-bedded rivers, such as the Mekong, provide a readily available source of construction-grade sand which is used for global development. For example, the expansion of Singapore was driven by sand from Cambodia and Vietnam, until exports were banned. All of the land building along the Dubai coast, expansion of Chinese islands in the pacific, and many other urbanisation projects are all being built on dredged sand.”
Dr Hackney and the team, which included colleagues from the Universities of Southampton, Exeter and Illinois, initially measured how much sediment is naturally transported down the Mekong, either in the water column, or along the river bed, before comparing these figures with how much sand is being extracted by sand mining.
He said: “This research provides the first full quantification of the rates at which sand is transported along the Mekong. By comparing these new estimates of sand flux with current rates of sand mining and by estimating the volume of sand stored in the bed of the Mekong, we have provided the first comprehensive overview of the extent to which current rates of sand extraction are completely unsustainable.
“Our research shows people are removing sand at rates that are over five, and perhaps up to nine, times the rate at which it is moving down the river naturally per year.
“Sand is mined using large pipes that are lowered from barges onto the riverbed and the sand is effectively sucked up by big pumps.”
Sonar imaging of the river undertaken as part of the study has shown giant holes 42m in length and up to 8m deep on the river bed, left after sand has been removed from the Mekong.
“The consequence of this is that the river beds are lowering and the adjacent riverbanks are becoming unstable and begin to collapse,” says Dr Hackney.
Most importantly, the study has also showed that it only takes about 2 m lowering of the river bed to make riverbanks unstable, and we’ve seen that dredging pits can be nearly 8 m in depth. The river bank failures are continual and are up to tens of metres per year. People’s houses have started falling into the river, roads are being destroyed, and the riverbanks are having to be protected and reinforced at great cost.
“The river has always been the lifeline of these communities – it’s how they get their food, their transport routes are mainly by boat and people live close to the river banks. Added to that, their main source of protein is fish so if you remove the sediment, you also impact river habitat for many of the fish species, which can therefore affect the whole natural ecosystem balance.”
Dr Hackney warns that without proper regulation, sand mining could have increasing environmental and social consequences.
“Local communities have started to realise the impact mining can have and there has been a lot more awareness from communities on the riverbank, who have begun to associate sand mining and the banks collapsing. Residents say they look for cracks extending from the banks – if they see the cracks starting to form, they don’t go in the houses.”
Dr Hackney, says greater regulation of the industry is needed to avoid these consequences.
“We need sand – we can’t get away from that,” he said. “But there has to be a realisation that the impacts of this are much graver than we think. There needs to be wholesale changes in the ways we mine and use sand. Oil and gas have really well regulated, governed and monitored frameworks, which sand doesn’t have. We need similar systems for regulating sand. We need to also start thinking about ways we can reduce sand use.”
Dr Hackney says alternative materials and alternative designs that limit the use of concrete or glass as well as reusing sand from demolition, as was done in the construction of the new Tottenham Hotspur stadium, rather than throwing it into landfill.
He said: “We also need to look at ways we can start using other forms of sand, like desert sand, which can’t be used in construction because it is too round and smooth, but there are ways in which we can make it more useful, which would then relieve some of the pressure on sand mining along rivers and coasts. Sand mining is not just taking homes, it is taking livelihoods, there’s a knock-on effect. Anywhere you have a river with sand, people will be that taking sand out. We need a global regulatory approach to avoid a sustainability crisis.”