Sand and gravel are used extensively in construction. In the
preparation of concrete, for each tonne of cement, the building industry
needs about six to seven times more
tonnes of sand and gravel (USGS,
2013b). Thus, 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 production represents enough concrete to build a wall 27 metres
high by 27 metres wide around the equator. Aggregates also contribute to
90% of asphalt pavements and 80% of concrete roads and the demand for
aggregates stems from a wide range of other sectors, including
production of glass, electronics and aeronautics. 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.
This sand and gravel are mined world-wide and account for the largest
volume of solid material extracted globally and the highest volume of
raw material used on earth after water (about 70-80% of the 50 billion
tons material mined/year). Formed by erosive processes over thousands of
years, they are now being extracted at a rate far greater than their
Despite our increasing dependence on the colossal quantities of sand
and gravel being used and the significant negative 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. Indeed,
the absence of global data on aggregates mining makes environmental
assessment very difficult and has contributed to the lack of awareness
about this issue. As a consequence, a large discrepancy exists between
the magnitude of the problem and public awareness of it.
Where and how much sand and gravel are mined?
The amount being mined is increasing exponentially, mainly as a result
of rapid economic growth in Asia and the resulting boom in construction.
A conservative estimate of 40 billion
tonnes /yr for the world
consumption of aggregates is twice the yearly amount of sediment carried
by all of the rivers of the world. Cement demand by China has increased
exponentially by 430% in 20 years, while use in the rest of the world
increased by 60%. Surprisingly, reliable data on their extraction in
certain developed countries are available only for recent years. Sand
was until recently extracted in land quarries and riverbeds; however, a
shift to marine and coastal
aggregates mining has occurred due to the decline of inland resources.
River and marine aggregates are now the main sources for building and
The sand that is found in most deserts is paradoxically unsuitable for
concrete and land reclaiming, as the wind erosion process forms round
grains that do not bind well. On the other hand,
marine aggregate needs to be
thoroughly washed to remove salt. If the
sodium is not removed from
marine aggregate, a structure built with it might collapse after few
decades due to corrosion of its metal structures. For concrete,
in-stream gravel requires less processing and produces high-quality
What are the main issues with sand mining?
Negative effects on the environment are unequivocal and are occurring
around the world. The volume being extracted is having a major impact on
rivers, deltas and coastal and marine
ecosystems, sand mining results in
loss of land through river or coastal erosion, lowering of the water
table and decreases in the amount of sediment supply. Table 1 summarizes
some of the impacts that are observed.
Table 1: Summary of the main consequences of extraction of
||Impacts on related ecosystems (for
||Both inland and coastal through erosion
||Change in water flows, flood regulation and
||Through lowering of the water table and pollution
||Damage to bridges, river embankments and coastal
||Directly through transport emissions, indirectly through cement
||Coastal erosion, changes in deltaic structures, quarries,
pollution of rivers
||Decline of protection against extreme events (flood, drought,
Extraction has an impact on
biodiversity, water turbidity,
water table levels and landscape
and on climate. There are also socio-economic, cultural and even
political consequences. The problem is now so serious that the existence
of river ecosystems is threatened
in a number of locations, damage being more severe in small river
catchments. The same applies to threats to
benthic ecosystems from
marine extraction . In
some extreme cases, the mining of marine aggregates has changed
international boundaries, such as through the disappearance of sand
islands in Indonesia.
Sand and gravel mining also has also climate impact. It has a direct
impact through greenhouse gas
emissions from both the extraction process itself and the transport,
sometimes over long distances of the mined materials. It also has an
indirect impact from the production of cement for use in concrete
together with sand and gravel: for each tonne of cement, an average of
0.9 tonnes of
carbon dioxide are produced.
Emissions of 1.65 billion tonnes of carbon dioxide were estimated from
cement production in 2010 alone (about y 5% of total greenhouse gas
emissions) and total carbon emissions from cement amount to about 30
billion tonnes of carbon dioxide.
The absence of global monitoring of aggregates extraction undoubtedly
contributes to the gap in knowledge, which translates into a lack of
What is the specific negative impact from marine sand mining?
The mining of marine aggregates
is increasing significantly and although the consequences of substrate
mining are hidden, they are tremendous. Marine sand mining has an impact
on seabed flora and fauna. Dredging and extraction of aggregates from
the benthic (sea bottom) zone
destroys organisms, habitats and
ecosystems. It deeply affects
the composition of biodiversity,
usually leading to a net decline in faunal biomass and abundance or a
shift in species composition. Longterm recovery can occur only where
original sediment composition is being restored.
Aggregate particles that are too
fine to be used are rejected by dredging boats, releasing vast dust
plumes and changing water turbidity, resulting in major changes to
aquatic habitats over large areas.
Box : The cases of Dubai & Singapore
What is the impact on coastal and inland erosion?
Erosion occurs largely from direct sand removal from beaches, mostly
through illegal sand mining. In Morocco, sand smugglers have transformed
a large beach into a rocky
landscape. Erosion can also occur
indirectly, as a result of near-shore
marine dredging of aggregates,
or as a result of sand mining in rivers. Damming and mining have reduced
sediment delivery from rivers to many coastal areas, leading to
accelerated beach erosion. Onshore sand mining in coastal dune systems
can also lead to long-term erosion sometimes of 0.5 to 1.5 metres a
Global average sea level rise, which is expected to reach 0.25 to 0.5
metres by 2100 under the best-case scenario (of 70% reduction of
greenhouse gas emissions)
is particularly acute for small islands states, where retreat options
are limited. In the Maldives, to strengthen the capital Male, a large
amount of sand is being imported to be used in building higher towers
and coastal protection. The sand is taken from offshore sand islands.
Paradoxically, the sands extracted for the protection measures in Male
are leading to the lowering of these other islands, increasing the need
to relocate their
Sand mining has led to deepening and widening of the Lake Poyang
channel, the largest freshwater
lake in China and a biodiversity
reserve of exceptional importance, and to an increase in water
discharge into the Yangtze
River. This may have influenced the lowering of the lake’s water levels,
which reached a historically low level in 2008.
What is the Impact of sand mining on inland biodiversity and rivers?
The mining of aggregates in rivers can have an effect on pollution and
change the level of water acidity
(pH). Removing sediment from rivers causes the river to cut its channel
through the bed of the valley floor (or channel incision) both upstream
and downstream of the extraction site. This leads to coarsening of bed
material and lateral channel instability. It can change the riverbed
Incision can also cause the alluvial
aquifer to drain to a lower
level, resulting in a loss of aquifer storage. It can also increase
flood frequency and intensity by reducing flood regulation capacity.
However, lowering the water table is most threatening to water supply,
exacerbating drought occurrence and severity as tributaries of major
rivers dry up when sand mining reaches certain
Are there economic impacts related to sand mining?
Tourism may be affected through beach erosion. Sand is often removed
from beaches to build hotels, roads and other tourism-related
infrastructure. In some locations, continued construction is likely to
lead to an unsustainable situation
and destruction of the main natural attraction for visitors, the beaches
Fishing — both traditional and commercial — can be affected through
destruction of benthic fauna and
agriculture could be affected through loss of agricultural land from
river erosion and the lowering of the water table. The insurance sector
is affected through exacerbation of the impact of extreme events such as
floods, droughts and storm surges
through decreased protection of beaches. The erosion of coastal areas
and beaches affects houses and infrastructure as a decrease in bed load
or channel shortening can cause downstream erosion including bank
erosion and the undercutting or undermining of engineering structures
such as bridges, side protection walls and structures for water supply.
What can be done to reduce the problems?
By reducing the consumption of sand
One way is to reduce consumption of sand by optimising the use of
existing buildings and infrastructure. Recycled building and quarry dust
material can be a substitute for sand. Despite the very high value of
minerals found in the sand, it is mostly used for concrete or is buried
under highways. Concrete rubble should be recycled to avoid using
aggregates, at least for low-quality uses. Recycling glass bottles would
also reduce sand consumption. Also, substitutes for sand are available.
Quarry dust could be used to replace sand in general concrete
structures. The replacement of sand by up to 40% of incinerator ash
exhibits higher compressive strength than regular cement mortars. Some
desert sand can be used if mixed with other material.
There are also alternatives to concrete for building houses, including
wood, straw and recycled material. However, the current building
industry is geared toward concrete know-how and equipment. Training of
architects and engineers, new laws and regulations, and positive
incentives are needed to initiate a shift for lowering our dependency on
sand. Renewable and recycled materials need to be targeted for building
houses and roads.
By setting taxes on aggregates extraction to create incentives
The current situation will continue unless sand extraction is
correctly priced and taxed so that other options become economically
viable. Because sand is still very cheap – sand itself is freely
accessible; only extraction costs need to be covered – there is little
or no incentive to induce a change in our consumption.
Alternative sources of sand and gravel, such as those that accumulate
at the bottom of dams, can also be targeted. large amounts of water must
reguraly be released from dams to flush out agg; although currently more
expensive, these aggregates could be extracted from the dams. Their use
would address the problem of their accumulation, which leads to a
reduced capacity of dams to store water and could result in the dams’
water intakes being blocked.
By reducing the negative consequences of extraction
The environmental impact of in-stream mining might be avoided if the
annual bed load were calculated and the mining of aggregates restricted
to that value or less. Local environments should be studied to define
the limits of acceptable changes.
Which regulatory initiatives should be applied to manage the issues?
Sand trading is a lucrative business, and there is evidence of illegal
trading such as the case of the influential mafias in India, and in
Morocco, half of the sand – 10 million cubic metres a year – comes from
illegal coastal sand mining.
The lack of proper scientific methodology for river sand mining has
led to indiscriminate sand mining while weak governance and corruption
have led to widespread illegal mining. The lack of adequate information
is limiting regulation of extraction in many developing countries.
Access to data is difficult, and data are not standardised. There is
limited collaboration/co-ordination between the
marine scientific research
establishments and the marine aggregates industry. Except in the
European Union, regulation efforts are few, especially in developing
countries. Lack of monitoring systems, regulatory policies and
environmental impact assessments have led to indiscriminate mining,
triggering severe damage to the environment and related
As this issue is a major emerging one, there is a need for in-depth
research. The implementation of a monitoring mechanism regarding global
aggregate extractions and trade would shed light on the magnitude of
this issue and bridge the current data and knowledge gap. This would
also raise this issue on the political agenda and perhaps lead to an
international framework to improve extraction governance, as the current
level of political concern clearly does not match the urgency of the
Whilst it is critical for political leaders to take appropriate
measures, the mining of aggregates has not yet reached their political
agenda. This is primarily because sand loss has not yet reached a level
of scarcity that would threaten the economy. Few, if any, measures are
being implemented , with the notable exception of the European Union,
and the United Kingdom in particular. While no international conventions
regulate the extraction, use and trade of land-based sand (sand quarry,
riverine and lake aggregate), the United Nation Convention on the Law of
the Sea, 1982 (UNCLOS) provides for the delimitation of maritime zones
and regulates rights and obligations in respect of usage,
preservation for these zones, including resource mining. If a number of
existing regional Conventions on
marine protection , directly or
indirectly, references to aggregate exploitation, the governance is not
coherent and includes several layers of regulations between national and
There is thus a need for regulating sand extraction in both national
and international waters and it should be authorized only after sound
scientific assessment shows there would be limited impact on the
environment. Greater consideration of substitute and
sustainable use of the resource
could drastically reduce impact on the environment. Other policy actions
include the introduction of scientific mining operations, followed by