Illegal and indiscriminate sand mining will become a threat to the worldwide environment. ‘’Sand mining‟ is a practice that is used to extract sand from various environments, such as beaches, inland dunes and dredged from ocean beds, and river beds of deltaic regions. The mining is in operation in all the continents of the Globe. Environmental problems occur when the rate of extraction of sand, gravel and other materials exceeds the rate of deposition. Sand budget of a particular environment shall be observed before sand mining. Specific hydrologic and hydraulic information are necessary.
Sand mining has several impacts on the river environment. Sand mining disturbs and completely removes the habitat from the mined zones. It leads to changes in its channel form, physical habitats and food webs – the river’s ecosystem. It also increases the velocity of flow in rivers which destroy flow-regime and eventually erodes the river banks.
Channel widening causes swallowing of the streambed, producing braided flow or subsurface inter-gravel flow in riffle areas, hindering movement of fishes between pools. Riverbed becomes dry due to exposure to solar radiation, thus decreasing the surface and groundwater. Depletion of sand in the streambed causes the deepening of rivers and estuaries, and the enlargement of river mouths and coastal inlets. It leads to saline-water intrusion.
Removal of vegetation and destruction of the soil profile destroys habitat above and below the ground and faunal population decreases. Fall in the riverbed and removal of sand from beneath topsoil at the river embankment resulted in caving into the river in many places. Beach formation begins with erosion of continental material. It forms sand, gravel, and cobble fragments, which transport to sea by Rivers. Mine sediment is suspended in sea water and transported along the coast by the longshore current. Sand dunes are present on shorelines where fine sand is transported landward by a combination of wind and waves and stabilized with vegetation.
Dunes can help protect coastal property from the destructive forces of storm surges and tsunamis. However manmade had severe impacts on coastal sand dunes. Sand dunes are part of the beach system and provide reservoirs of sand that feed the beach during tropical storms and hurricanes. If they are destroyed, coastal lands are vulnerable to flooding. Sand dunes play an important role as barriers against heavy storms, erosion through waves or floods. Destruction of picturesque beaches causes tourism to dissipate. They serve as habitat for many small animals and plants that are part of the marine and coastal food web and whose loss implies a threat to other species as well. Beach erosion takes place because of sand mining and affects homes and livelihoods. The process of sand mining has accelerated coastal environmental degradation to an alarming rate.
Sand mining is one of the main threats to the rich biodiversity alongside our perennial rivers and ephemeral water courses. It can destroy riverine vegetation, cause erosion, pollute water sources and reduce the diversity of animals. The beach and dune system habitat along the coastal zones also victims.
Off-shore sand mining pumping biota with sand and damaging coastal ecosystems. Many species of trees and shrubs in dry riverbeds are supported by groundwater retained by the river and at varying depths will disappear.
Operation of heavy equipment in the channel bed can directly destroy spawning habitat for fish and macroinvertebrate habitat, and produce increased turbidity and suspended sediment downstream. The sediment in the mining site, if contains toxic material due to long time accumulation, will cause a second time pollution. Physical disturbance of the habitat caused by dredging activities includes noise, which can interrupt nesting/breeding activities.
Hydrologically on the river bed the sand acts as a spongy, natural carpet and as a good aquifer. Sand aquifer helps in recharging the water table and sand mining causes sinking of water tables in the nearby areas. Apart from threatening bridges, sand mining transforms the riverbeds into large and deep pits; as a result, the groundwater table drops leaving the drinking water wells on the embankments of these rivers dry.
Turbidity increases at the mining site due to resuspension of sediment, sedimentation due to stockpiling, organic particulate matter, oil spills or leakage from excavation machinery and transportation vehicles.
Saline water intrusion takes along the coastal aquifers. Acid mine drainage also dissolves toxic metals, such as copper, gold, silver, molybdenum, aluminum, cadmium , arsenic, lead and mercury, from the surrounding rock. Even in very small amounts, metals can be toxic to humans and wildlife. If uncontrolled, the acid mine drainage may runoff into streams or rivers or leach into groundwater. Plants, animals, and fish are unlikely to survive in such streams.
Large quantities of dust enter into the atmosphere during sand mining cause respiratory disorders. Noise is an issue in the mining areas because mines normally operate 24 hrs. day and sound levels fluctuate widely. The noises pollute the environment and disturb sleep. Roads and other structures movement of heavy vehicles cause damage to roads and bridges and sometimes cause traffic hazards.
Sand mining has many negative impacts on society. It affects the livelihood of the people, health, scenic beauty, climate and damages infrastructure. The beaches and backwaters of coastal areas are famous for their scenic beauty. Beach and backwater tourism is one of the main areas for economic development. There are pockets along the coast with harbors and commercial centers. We can’t see the beauty in the near future.
People living in the coastal areas are under the constant threat and fury of nature wherever the sand mining is carried. Coastal erosion causes damage to the properties leading to social discontent. Extraction of beach sand exposes coastal areas to the ravages of erosion. The residue of the radioactive mineral such as monazite and zircon, detrimental to local biota. Problems are not the least in Manipur too. It’s a well-known fact about the problems caused by sand mining in Sekmai River, Thoubal River, Serou River and even in Lokchao in Tengnoupal district and many other places of Manipur.
Minerals are part of a nation’s natural wealth. The nation is to advance industrially and economically by the proper development and exploitation of these resources. It has to be remembered that the sand once removed cannot be replaced in the next generation. It will take centuries for replacement. Sand sustains the rivers and the percolation of water to far off distances both for the growth of trees to sustain drinking water and raise cultivation.
It is almost a lifeline to human existence. Without considering the precise gift provided by nature, commercial exploitation for short term gains by pumping out the sand indiscriminately from the rivers, dunes and beaches will destroy the whole environment. People employ huge machinery like cranes and other pumping mechanisms causing untold natural calamities and loss to the society. In order to maintain the balance between the environment and sand mining, the governments should regulate the mining.
(The views expressed are personal)
