Sand mining: the most under-reported environmental crisis of all
In 2012, the amount of sand the world used would form a wall 27m high and 27m wide around the equator. I’ll just let that statistic sink in, an easier way perhaps to visualize some 40 billion tonnes of sand, twice the annual sediment output of all the world’s rivers combined .
After water, sand is the most extracted material on the planet : we live and work in buildings made of sand, built on sand, with windows of sand. Capitalism, it could be said, is simply an edifice of sand: sand mixed with water and limestone, cement and concrete, glass and asphalt, 79% of all infrastructural materials . It shouldn’t be a surprise that sand mining wreaks a heavy toll on the environment, but worryingly, the journalistic and scientific world appears to have only just woken up to it. Despite a textbook published by two Indian authors in 2011  (which I haven’t read due to paywall), there’s a paucity of literature in the field, a field which appears shadowy and illegal. In short, I was shocked at the systemic scale of sand mining, and I hope you’ll be too. It’s arguably the most under-reported environmental crisis of the modern times.
However, the sparseness of domestic journalistic coverage is hardly surprising when the penalty of death looms large over it, especially in India where sand mafias bribe politicians and businessmen in return for their omertà and freshly-dredged delta channels . Three journalists and a monk have been killed recently in India for reporting illegal sand mines , activists frequently hospitalized  ; small skirmishes periodically flare up in remote locations over village rights and the endemic corruption of sand mafia pay-outs, killing an undetermined number . It’s easy to see what precludes scientific study, not just in India but across Asia, from Bangladesh to Nepal, whether the sand is mined by hand by free-divers or mined blatantly and industrially by barge and pump. The human stakes of sand mining surfaced in 2016 when 29 people died after a bridge collapsed near Mumbai, sand mining having destabilized its foundations . The economic stakes also couldn’t be higher, at $126 bn per annum in India alone .
Whilst sand might appear as an infinite resource, sand and gravel used in construction need angular grains to hold the cement together, and, ideally, they should be free of salt (which could cause the mortar to corrode) , making river and lakebed sand the only suitable candidate. Neither desert sand nor marine aggregate can be used, the grains too smooth, sculpted by wind and tide, flecked with salt: Dubai ironically became a net importer of sand from Australia when it built its Burj Khalifa . It’s perhaps unsurprising that river mining should wreak such a devastating toll when the sediment load determines the majority of the river’s geomorphology downstream, the effects exacerbated in what’s been termed ‘tele-coupling’ .
For instance, a 2015 study in Nature  enquired why the Mekong delta – the 3rd largest in the world – was losing 2.3 km2 of land per year. Channel mining was the major culprit, alongside sediment retention behind hydroelectric dams and over-abstraction of groundwater. Some 27 million m3 of sand were extracted in 2012, equivalent to 20 times the annual sand flux carried by the Mekong. The authors noted that when diggers excavate stretches of the riverbed the resulting pits trap sediment, the river’s attempt to restore its equilibrium profile; hence delta is deprived of sand, which makes the shoreline more vulnerable to the toll of cyclonic storms . What’s more, tidal flux can now push saltwater 40 km upstream due to the deeper channels , salinizing croplands; river turbidity also increases, large volumes of sediment stirred up, in suspension, blocking sunlight reaching aquatic plants .
I think it’s worth underlining just how radically the hydrology of the region is changed when the river channel is mined. As the river tries to regains its original hydraulic radius, it erodes laterally and undercutting banks, and when subsequent pools re-fill with sediment, the channel ends up wider and therefore shallower. More sediment is deposited, water temperatures are higher and more water is lost to evaporation, whilst channels meander more, becoming braided , their zig-zagged edges visible on satellite data . Areas are made prone to more landslides and flash-flooding, water no longer percolating to the water table slowly through sand, instead discharged in sudden bursts into the river following heavy rain . A 2017 metareview  highlights that sand mining is contributing to not just deformed and sunken river beds, but that it also lowers groundwater aquifers, causing wells to dry up and previously fertile land to turn barren. In the context of climate change, I find this detail – one that easily slips out of sight – particular threatening.
Satellite data from NASA highlights just how radically the Yangtze River has changed, the image showing the region just below Poyang Lake – China’s largest freshwater lake, and overwintering site for 98% of Siberian cranes – which is also now the world’s largest salt mine, extracting 236 million m3 of sand per year . Miners pounced on the site after Chinese court ruling in 2000 that mining the Yangtze was illegal. The incised channel now conveys a significantly greater volume of water through the lake – allegedly double the flow of the post-Three-Gorges-Yangtze River – which has contributed to the lake bed drying up outside the channel, destroying fish breeding grounds  . In the Yangtze River itself, illegal sand mining is on the rise, and it has been cited as a major contribution in the demise of the officially-extinct Yangtze river dolphin, and is in the process of making the now critically-endangered Yangtze finless porpoise extinct, by disturbing their spawning grounds .
NASA Earth Observatory images  which show the damage caused by sand mining in Poyang Lake and in the lower Yangtze (in picture); notice the jagged edges
Already, the myriad of damage that river sand mining causes seems overwhelming: add to that an increased volume of spawning grounds for Anopheles sp. mosquitos, the vector of malaria, and the situation becomes even scarier. In an area of Iran studied in a 2016 paper , the most common larval habitat for Anopheles sp. were sand pools on the river side – stagnant, clear water in full sunlight – whilst similar observations were recorded in central Ethiopia  and Eritrea. What worries me is how increasingly stagnant water will interact with rapidly urbanizing populations, especially when combined with flash flooding capable of carrying pathogens into the heart of urbanizing cities.
Nonetheless, I think that the scariest detail of all is that sand mining seems to have no end, Western Europe the only region to have comprehensive policies to restrict it. Theoretically, yes, concrete rubble can replace high-quality sand used in motorways, quarry dust can be repurposed , and sediment behind dams can be collected to replace some sand, but when sand is so cheap, of such constant price, and so freely accessible, there is no incentive for change , least of all in Asian markets where sand is the fuel of their economic growth.
Sand, symptom of capitalism, is the quiet cap on all economic growth. So, will the world manage river sand mining sustainably, or will the sand mafias continue their illegal destruction, precluding most scientific study? I am not optimistic.
 The Guardian, 30/12/17, Villagers pay tragic price as Indian building boom drives demand for sand, https://www.theguardian.com/world/2017/dec/30/india-sand-mining-conflict-deaths-building-boom-environmental-damage
 Times of India, 4/8/16, Illegal sand mining eroded Savritri bridge foundation, led to collapse, https://timesofindia.indiatimes.com/city/mumbai/Illegal-sand-mining-eroded-Savitri-bridge-foundation-led-to-collapse/articleshow/53548289.cms
 The Guardian, 27/2/17, Sand mining: the global environmental crisis you’ve probably never heard of, https://www.theguardian.com/cities/2017/feb/27/sand-mining-global-environmental-crisis-never-heard
 Journal of Vecotr Bourne Diseases, Environmental factors associated with larval habitats of anopheline mosquitoes (Diptera: Culicidae) in irrigation and major drainage areas in the middle course of the Rift Valley, central Ethiopia, Kenea et al., 2011
All pictures are sourced from the public domain, except where otherwise attributed.