Sand and gravel are mined world-wide and account for the largest volume of solid material extracted globally. Formed by erosive processes over thousands of years, they are now being extracted at a rate far greater than their renewal. Furthermore, the volume being extracted is having a major impact on rivers, deltas and coastal and marine ecosystems, results in loss of land through river or coastal erosion, lowering of the water table and decreases in the amount of sediment supply. Despite the colossal quantities of sand and gravel being used, our increasing dependence on them and the significant impact that their extraction has on the environment, this issue has been mostly ignored by policy makers and remains largely unknown by the general public.

Using cement production has proxy, the world’s use of aggregates for concrete can be estimated at 25.9 billion to 29.6 billion tonnes a year for 2012 alone. This represents enough concrete to build a wall 27 metres high by 27 metres wide around the equator (just for 2012).

Added to this are all the aggregates used in land reclamation, shoreline developments and road embankments (for which the global statistics are unavailable), plus the 180 million tonnes of sand used in industry. Hence a conservative estimate for the world consumption of aggregates may exceed 40 billion tonnes a year. This is twice the yearly amount of sediment carried by all of the rivers of the world, making humankind the largest of the planet’s transforming agent. Such high extraction has tremendous impacts on the environment.

Sand extraction impacts several sectors: tourism through beach erosion, fisheries due to destruction of benthic fauna and flora, insurances, as sand extraction in river can lower the water table (leading to more severe drought) and exacerbate flooding, coastal erosion increase the impacts from storm surges.

A global mechanism is needed to monitor the sand extraction and its impacts. Scientific and environmental impact assessments should be systematically implemented prior any authorisation for sand extraction.

Other solutions include optimization of the building infrastructure. Replacement of sands by recycling concrete, using ash from waste, substitution of concrete by recycled material in the construction.

The report is available at:
http://na.unep.net/geas/archive/pdfs/GEAS_Mar2014_Sand_Mining.pdf

More information: Pascal.Peduzzi@unep.org