Sand Mining
Sand Mining
1. Introduction:
Sand has become a very important mineral for the expansion of society. Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. River sand is one of the world’s most plentiful resources (perhaps as much as 20% of the Earth’s crust is sand) and has the ability to replenish itself. River sand is vital for human well being & for sustenance of rivers.
As a resource, sand by definition is ‘a loose, incoherent mass of mineral materials and is a product of natural processes.’ These processes are the disintegration of rocks and corals under the influence of weathering and abrasion. When sand is freshly formed the particles are usually angular and sharply pointed but they grow gradually smaller and more rounded as they become constantly worn down by the wind or water.
2. Importance of Sand:
Sand has become a very important mineral for our society due to its many uses. It can be used for making concrete, filling roads, building sites, brick-making, making glass, sandpapers, reclamations, and etc. The role of sand is very vital with regards to the protection of the coastal environment. It acts as a buffer against strong tidal waves and storm surges by reducing their impacts as they reach the shoreline. Sand is also a habitat for crustacean species and other related marine organisms. Sand also plays an important role in our tourism industry as it is an integral part of our beach attractions. Each has its own requirements in respect of the quality of the sand. On average, people 'use' over 200kg of sand per person per year. This sand is taken from what are essentially non-renewable resources.
3. Constituents of Sand:
Clean sand is indeed a rare commodity on land, but common in sand dunes and beaches.
The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz which because of its chemical inertness and considerable hardness, is the most common mineral resistant to weathering. The bright white sands found in tropical and subtropical coastal settings are eroded limestone and may contain coral and shell fragments in addition to other organic or organically derived fragmental material. The gypsum sand dunes of the White Sands National Monument in New Mexico are famous for their bright, white color. Arkose is a sand or sandstone with considerable feldspar content, derived from the weathering and erosion of a (usually nearby) granitic rock outcrop. Some sands contain magnetite, chlorite, glauconite or gypsum.
ISO 14688 grades sands as fine, medium and coarse with ranges 0.063 mm to 0.2 mm, 0.25 mm to 0.50 mm and 0.63 mm to 2.0 mm respectively.
4. Sand Mining:
Sand Mining is a coastal activity referring to the process of the actual removal of sand from the foreshore including rivers, streams and lakes. Sand is mined from beaches and inland dunes and dredged from ocean beds and river beds. A related process is the mining of mineral sands, such as mineral deposits like diamond, gold and silver. These minerals typically occur combined with ordinary sand. The sand is dug up, the valuable minerals are separated in water by using their different density, and the remaining ordinary sand is re-deposited.
Individuals and private companies are increasingly demanding sand for construction purposes and this has placed immense pressure on sand resources. It is a practice that is becoming an environmental issue as the demand for sand increases in industry and construction.
5. Sand Mining IN INDIA:
Sand Mining in India is adversely affecting the rivers, sea, forests & environment. Illegal mining of Sand and the lack of governance, in a big way is causing land degradation and threatened its rivers with extinction.
Mining of sand, for instance, is depleting the waters of the rivers. Weak governance and rampant corruption are facilitating uncontrolled and illegal mining of sand and gravel in the rivers, threatening their very existence.. This unrestrained and unregulated activity is posing threats of widespread depletion of water resources which may lead to avoidable food shortages and hardships for the people.
In M.P. the major rivers like Narmada, Chambal, Betwa or Wainganga or numerous rivulets and streams all are being ravaged for their sands. The state government has wittingly lent a helping hand by exempting the grant of Environmental Clearance to be taken for mining of sand and gravel, neutralising the provisions made in several central legislations on conservation of environment and mineral resources. A social activist has approached the state high court for quashing of the unconstitutional exemptions so that indiscriminate mining of sand could be put a stop to.
Similarly River Bharathapuzha in Kerala has become a victim of indiscriminate sand mining. “Despite numerous prohibitions and regulations, sand mining continues rapidly on the riverbed of the Bharathapuzha. Water tables have dropped dramatically and a land once known for its plentiful rice harvest now faces scarcity of water...In the villages and towns around the river, groundwater levels have fallen drastically and wells are almost perennially dry.
The malaise is pretty widespread as many other states, like Gujarat, Karnatak, Tamilnadu, etc are also victims of unchecked illegal sand-mining the consequences of which are very serious. Rivers of India are already seriously sick. Polluted by industrial and urban effluents, they are also victims of deforestation in their catchments, sequential damming and degradation because of unchecked sand-mining on their banks and beds. Besides, erratic monsoons, induced by changing climate is taking its toll, adversely impacting their capacity to sustain the current levels of economic activities, especially agricultural productivity.
6. Offshore sand mining: prospects:
Mining of off shore sand became a topic of interest recently because of the increasing demand and spiraling cost of river sand for construction purposes. Often proposed as an alternative to beach mining, is offshore sand mining. Extensive (and expensive) studies must be conducted before any offshore mining can be attempted. Offshore sand banks, coral reefs and sea-grass beds diffuse the energy of storm waves; if large quantities of sand are removed from offshore sand banks in locations where replenishment would not occur, serious coastal damage would result in the event of a major storm. A complex relationship exists between sand banks, coral reefs, marine biota, current circulation, waves and swell patterns. Offshore mining does present a possibility with an initially high price tag
Sand mining in coastal regions is subject to different regulations throughout the world. While a minimum water depth is commonly used as a restrictive criterion for providing mining licenses in numerous countries. In a general erosional context of sandy coasts, such practices are often (rightly or wrongly) held responsible for beach recession.
7. In Indian Context:
Kerala offshore, being supplied with river sediment from number of smaller west flowing riversmakes off shore bars, serves as possible sand source. However, the question of off shore sand mining is to be viewed carefully and cautiously. Sand mined in the offshore sites is usually washed in the site itself to take the suitable granular aggregate. This procedure can lead to more turbid and muddy environment in the mining site, which is considered as detrimental to marine fauna and fishes. Further, such sands will be salty and is not a good building material. The salt in the sand corrodes reinforcing beams and degrades the quality of the concrete.
8. In Global Context:
Offshore sand is being mined in France in the name of clearing of river mouths. It has been reported that "clearing river mouths" is not all that is being done. Beaches have been mined where there are no real rivers, and more importantly, all sand cleared from river mouths has been trucked away to be used or sold when, if clearing the river mouth was all that was being done, the sand could have been more easily moved down the beach.
9. Effect of Sand Mining:
Sand mining is a direct and obvious cause of erosion, and also impacts the local wildlife. Disturbance of underwater and coastal sand causes turbidity in the water, which is harmful for such organisms as corals that need sunlight. It also destroys fisheries, causing problems for people who rely on fishing for their livelihoods.
Removal of physical coastal barriers such as dunes leads to flooding of beachside communities, and the destruction of pictures beaches causes tourism to dissipate. Sand mining is regulated by law in many places, but is still often done illegally.
Unsustainable sand mining can cause disturbance of coastal marine ecosystems and upset the ability of natural marine processes to replenish the sand. Erosion problems may worsen especially during severe storms and may also result in the alteration of our shorelines. Mining from streams or rivers upstream can reduce water quality for downstream users and poison aquatic life.
Seawater quality can be contaminated due to subsoil of the waterbed being surfaced and this may also reduce light penetration necessary for marine organisms to feed.
Geologists know that uncontrolled sand mining from the riverbed leads to the destruction of the entire river system. If sand and gravel is extracted in quantities higher than the capacity of the river to replenish them, it leads to changes in its channel form, physical habitats and food webs – the river’s ecosystem. The removal of sand from the river bed increases the velocity of the flowing water; the distorted flow-regime eventually erodes the river banks. Beside these, on-site effects the off-site effects are also quite lethal. Sand acts like a sponge, which helps in recharging the water table; its progressive depletion in the river is accompanied by sinking water tables in the nearby areas, adversely impacting people’s daily lives, even their livelihood.
10. Solutions:
The Ministry of Natural Resources and Environment recognizes the threats that unsustainable sand mining poses on the environment and society. Now a days sand borrowing from most of our rivers has been temporarily stopped which created impasse and panic on construction front. Mining of sand from the former is not freely permitted globally because of the very sensitive and dynamic nature of the coastal zone.
This situation has warranted the need for exploring alternatives for granular sandy material. Sandy material, available in the coastal and near shore environment forms a potential source. This problem is now solved to some extend by substituting river sand with crusher sand. Further, adulterated sands, which is a mixture of sand from estuary and coastal land, also is freely used for the construction.
11. Other Alternatives:
Sand Produced by Crushing Quarried Rock
Crushing rock produces sand or "crusher dust" provides a potential alternative to river sand in Kerala because of the abundant hard rock exposures constituting the western Ghats. Number of crushing plants operating in different parts, supply sufficient quantity of crusher sands to the construction sites. Nevertheless fascination for river sands is not yet over. Although crusher sands appear to be acceptable alternative, energy spent for making this aggregate as well as the environmental damage causes to neighbor hood through dust and sound is enormous.
12. Conclusion:
Although Sand is required for development of Human being, but at the same time the threats posed due to sand mining can’t be ignored. Hence decisive steps are to be taken & alternate solution to be found out for sand mining, without disturbing the environment.