After Sand Mining Ban, Quarries Devour Buffer Forests Of Western Ghats

In Kerala, the demand for river sand, one of the primary materials used in construction, has increased in line with development. The state has experienced rapid expansion in modern housing, partly fuelled by remittances from the Gulf since the 1970s oil boom and large-scale migration from the state. As Kerala’s demand for sand grew sharply, the state’s riverbeds bore the brunt — leading to falling groundwater levels, disrupted stream flows, and weakened bridges.

To prevent these consequences, in June 2015, the Kerala government banned sand mining in six rivers and restricted it in five others. In January 2016, the central government amended the Environmental Impact Assessment Notification of 2006, mandating prior environmental clearance for the mining of minor minerals, including sand, in areas less than or equal to five hectares.

While this was a well-intended move, a new study shows that the ban on river sand mining may have led to an unexpected boom in stone quarrying across the Western Ghats. The study was published by a team of three researchers from the National Institute of Technology, Kozhikode.

The study attains added significance in the light of the Revenue Department of Kerala issuing an order in May 2025, approving new guidelines for the resumption of river sand mining in the state, effectively lifting a nearly decade-long moratorium.

The study noted that the state’s construction industry, the largest consumer of the mined river sand, reacted to the ban by replacing river sand with manufactured sand (M-sand). M-sand is artificially made from crushing hard rocks into fine particles. Though it is thought to be more environmentally friendly than river sand, there are no studies proving that the environmental trade-offs are worth the shift. “This is especially true when the quarries supplying stones for the manufacture of artificial sand are located near ecologically sensitive areas,” notes the paper, published in the journal The Extractive Industries and Society.

As M-sand became the new construction staple, the Western Ghats, which is rich in granite and charnockite — a hard, dark, coarse-grained rock with a greenish tint, quarried widely in southern India — became the quarrying frontier, increasing the threats to this biodiverse ecosystem.

Expanding scars

Based on data from the state mining portal, Kerala Online Mining Permit Awarding Services (KOMPAS), the researchers identified 355 operational quarries spread throughout 32 talukas (of 12 districts). Of these, 72 quarries fall within the 10-kilometre buffer zone around 20 protected areas in the Western Ghats region.

“Using Google Earth tools and GIS, we analysed the expansion in the area of these quarries for 10 years, from 2011 to 2021. We noticed a more-than-normal increase in the year 2016,” says George K. Varghese, one of the authors of the study and an associate professor in the NIT department of civil engineering.

Between 2011 and 2015, 64 of the 72 quarries grew by a tenth of their original size. But the growth accelerated from 2016 to 2021, with 66 quarries expanding by at least another 10%. Five quarries increased more than fivefold — one even growing nine times larger. Overall, 90% of the quarries grew by over 50% during the decade. “The highest increase in the area was observed in quarries located in the 5 to 10-kilometre buffer zone,” the study noted.

Put together, the 72 quarries expanded by over 250 hectares between 2011 and 2021. Of this increase, 17.4 % occurred in 2016.

Lekshmi Ashok, co-author of the study and a NIT doctoral candidate, carried out a survey among residents near protected areas. “The majority considered stone quarrying as the most important threat,” says Varghese, who co-guided Lekshmi’s doctoral work along with Santosh G. Thampi, a professor in the same department.

Blast, din, dust

Beyond the removal of rocks, quarrying activity is accompanied by loud noises, dust, ground-shaking blasts, says the study, causing harm to the region’s biodiversity.

The study particularly noted that some quarries are very close to the protected areas. Silent Valley National Park has three quarries just four kilometres from its boundary, and the Malabar Wildlife Sanctuary, spread across Kozhikode and Wayanad districts, has 15 quarries within its 10 kilometre buffer, the study pointed out.

“Six quarries, two each in the buffer zones of Malabar Wildlife Sanctuary and Peechi-Vazhani Wildlife Sanctuary, and one each in the buffer zones of Idukki Wildlife Sanctuary and Thattekkad Bird Sanctuary, more than doubled their area in 2016 when compared to 2015,” the study noted.

The NIT team reviewed how quarrying affects local ecosystems, combing through academic databases such as Web of Science, Google Scholar, and Scopus to assess how noise pollution, dust, and vibrations affect birds, mammals, and plant life in ecologically sensitive areas.

Combined with real-time sound monitoring near active quarry sites, they could show that blasting produced noise levels well above safe thresholds — posing risks to wildlife and human settlements. The study involved deployment of a sound level meter near the quarry sites. During blasting, the noise level measured was 98 decibels (dB) at 50 m from the blast location, and the equivalent noise level (Leq) measured was 70 dB at 50 m of operational quarries. The equivalent noise level (Leq) is a single decibel value that represents the total sound energy of fluctuating noise over a set period as if it were a constant level. At noise levels above 40dB, the density of birds species decreased near the quarrying sites, as an earlier study found.

Better balance and enforcement

Meanwhile, experts have pointed out in formal reports and media comments the widespread presence of many illegal quarries in the Western Ghats. Eminent ecologist Madhav Gadgil, who has studied the region for decades, told Mongabay India that conservation laws are often poorly enforced. He cited the influence of powerful lobbies that bypass protections and pressure local communities to surrender their rights. “We need the rule of law,” Gadgil said in reference to illegal quarrying in the Western Ghats.

Kerala chief minister Pinarayi Vijayan has often defended the criticism about illegal mining in the Western Ghats, especially in landslide-affected areas.

Commenting on the relevance of study, Raghunathan Pillai, a former director of GSI, underscored the increasing use of concrete in Kerala. “Use of stones for basement construction is minimal now with the practice of making pillars even for small houses; but sand is an essential material for construction,” he said. “Rather than depending too much on M-sand, river sand can be brought from neighbouring states, and shipped from Gujarat. Another option is recovery of sand resources off Kerala coast after clearing environmental concerns. Use of suitable boards and wood in construction also can reduce consumption of sand,” he said.

GSI has identified approximately 750 million tonnes of construction-grade sand in offshore deposits off the Kerala coast — from Ponnani to Kollam — sufficient for nearly 25 years of the state’s demand. However, the Kerala government has opposed the move on environmental and procedural grounds.

By-products of industrial processes, crushed stone dust from quarries, recycled glass, demolition concrete waste, rice husk ash and coal combustion waste such as fly ash and bottom ash are some the other alternatives, as studies suggest.

Meanwhile, the NIT paper authors have called for an urgent overhaul of Kerala’s quarrying regulations. They recommend that ecologically sensitive zones be designated strictly off-limits for new quarry approvals, and that any major expansion in extractive activity undergo a strategic environmental assessment. Crucially, they call for mandatory public disclosure of quarry expansion data and biodiversity assessments — steps they argue are essential to restore transparency and accountability in the sector.