The Aravalli mountain range stretches from Gujarat in the southwest to Delhi in the northeast for about 700 km and sculpts the topography of eastern Rajasthan and adjoining parts of Haryana and Delhi, creating a picturesque backdrop for flourishing settlements, with its highest point at Guru Shikhar on Mount Abu in Rajasthan. At this point, the peak rises to about 1,722 m (5,653 feet). The ranges have a pronounced effect on the biodiversity and environment of the entire region and support open forests, famous forts and temples of historical importance apart from exerting a direct impact on the micro climate and the hydrological status of the area.
In appreciation of its importance, the British colonial government advocated for the protection and preservation of the Aravalli hills in undivided Punjab in the context of agriculture and water resource. They thus enacted the Punjab Land Preservation Act, 1900 (PLPA) which offered it protection and is in use even today. The significance of the Aravalli as the main source for aquifer recharge of the national capital region (NCR) cannot be over emphasised. The weathered rocks of Aravalli—fissured and highly jointed quartzite, schist and phyllites, make ideal zones for the percolation of rainwater and contribute to the aquifers below. Moreover, the forest cover over the Aravalli acts as lungs for the congested metropolis.
Aravalli mountains comprise two distinct group of rocks, geologically—the older meta sedimentary rocks with volcanics (>2,500 million years old) belonging to the Aravalli Supergroup and the younger sedimentary rocks intercalated with volcanic rocks belonging to Delhi Supergroup (1,700 million years or older), well known for its mineral wealth (Fig 1). The range hosts significant mineral deposits of base metals (copper, lead and zinc), noble metals (gold and silver) and building material such as marble, granite and more. It is no wonder therefore that the Aravalli have been supporting the mining industry from way back in history. The claim is backed by the existence of copper mines dating back to the fifth century BC (Srivastava, 1998), the presence of zinc smelters in the Zawar area of Rajasthan, dating to the thirteenth century (Craddok et al., 1985) and several historical monuments built using local construction material from this range.
Despite the exploitation, the hills were never ravaged, plundered and degraded to such a pathetic state as the one they are in now. The unregulated, chaotic mining and levelling of ridges to make way for real estate and rising demands of urbanisation in last five decades or so has brought widespread devastation and destruction. Moreover, unregulated and ill-planned quarrying (at places) has not only changed the relief and depleted the forest cover, but has also caused increased soil erosion, sediment transportation and siltation of water bodies, resulting in a ‘negative relief’ (Makrana) with pits and craters. The deep undercutting has also resulted in changes in the groundwater regime leading to the drying up of lakes and water bodies and lowering of the water table. The depleting forest cover over the hills following the increase in soil erosion has significantly lowered the water table up to 20 m or more in several districts (Rana, 2013).
As per a news report, the Aravalli have lost about 40 per cent of their total area over the last four decades (Thakur, 2017). The seriousness of the issue can be judged by the intervention of the Supreme Court of India, which responded to reports about the loss of 31 hills in the Aravalli area of Rajasthan and ordered the state government to stop illegal mining over a 115.34 hectare area. In another landmark judgment, pronounced in the case of M C Mehta Vs Union of India (2018), the Supreme Court observed that damage caused to the Aravalli hills in Haryana was irreversible and ordered the demolition of constructions along the forested tracts vide August 18, 1992 order, which would effectively allow no further construction in this region. This would save about 30,000 acres of the Aravalli from plunder in Gurgaon and Faridabad, currently notified under the PLPA.
According to the Aravalli notification of 1992, these mountains comprise of uncultivable hills (gair mumkin pahar), ravine foothills (gair mumkin beed), cultivable grassy foothills (banjar beed) and rocky areas between two hills (rundh). However, the unclear stand taken by Haryana State Government on the area along the ravine foothill may prove to be a great setback for preservation and safeguard of the hills and the green cover of the Aravalli. The Supreme Court judgment of September 2018 has directed the Haryana Government to treat all the area notified under PLPA as ‘forest’ and ‘forest land’.
Extensive mining for building materials, under improper mining leases, is rampantly practiced all along the Aravalli. Makrana is a case in point where open cast mining for marble is being undertaken for centuries resulting in an inverted relief, turning the once raised mountains into deep valleys and pits scattered all over the region. The waste created from the cutting and polishing of blocks and slabs—carbonate and calcium rich slurry is spread over a vast area degrading the soil, groundwater and turning the once forested slopes to a barren wasteland. Most of the districts in Rajasthan where Aravalli rocks are exposed, such as Alwar, Firozpur Jhirka, Jaipur, Ajmer, Kishengarh, Pali, Sirohi, Jalor and more, bear the brunt of ruthless scraping of the hill faces.
As granites found in the southern parts of Rajasthan are much in demand, these ranges are even more vulnerable.
According to a 2016 study of southern Haryana by the Wildlife Institute of India, the northern extension of Aravalli Range in Gurgaon, Faridabad, Mewat, Mahendargarh and Rewari districts of Haryana also represent the most ‘degraded’ forest range in India (Sharma, 2018). The study also found that many indigenous plant species have disappeared as construction led to the loss of habitat apart from posing a threat to wildlife. Another study undertaken by Rai and Kumar (2013) at Haryana Space Application Centre and published in International Journal of Remote Sensing covering Gurgaon, Faridabad and Mewat has provided quantitative details about the area under active and abandoned mining and vegetation cover in the Aravalli Ranges. The study shows 3D views riddled with large gaps/voids in the topography. Out of the total area of 1,18,736 hectares, the Aravalli hills occupy an area of 11,256 (9.48 per cent) hectares in the district of Gurgaon. The abandoned mines occupy an area of 16 hectares (0.14 per cent) while an area of 491 hectares (4.36 per cent) is designated as abandoned mine pits filled with water. An area of 8.63 and 14.24 per cent is under thick and sparse vegetation cover respectively (ibid). The deep pits that fall below the depth of the water table prove detrimental to both the sustenance and the quality of the aquifers.
In Faridabad district, the Aravalli hills are spread over 9,208 hectares out of which an area of 1,514 hectares (16.44 per cent) is under the category of abandoned mine pits, while an area of 227 hectares (2.46 per cent) is under abandoned mines filled with water. Fairly thick vegetation cover and scanty or sparse vegetation occupy 6.23 and 3.43 per cent of the area respectively.
Another district that has substantial presence of the Aravalli in Haryana is the Mewat district where the area under Aravalli hills is 19,965 hectares (12.08 per cent), out of which an area of 2,170 hectares(10.87 per cent) is under abandoned mine pits while 13 hectares (0.07 per cent) is under abandoned mines filled with water, 4.90 per cent is under thick vegetation and 10.90 per cent of the area is occupied by sparse vegetation.
Groundwater recharge from the Aravalli
It is not just the biodiversity and forest cover of the Aravalli that underscores their immense importance. The Aravalli also serve as a source of groundwater recharge for the cities of Gurgaon and Delhi, as well as many other cities in its ambit. The aquifers in these ranges are interconnected and any disturbance or alterations in the pattern can significantly alter the groundwater table. A Central Ground Water Board (CGWB) study from June 2017 mapped five transect in the Aravalli that help recharge the groundwater in Gurgaon. These are responsible for channelling groundwater to the Badshapur, Sector 56 and 45, Hariyahera and Bhondsi areas in the city. But with rampant mining and construction taking place in the foothills, the aquifers are increasingly threatened (Arora, 2017; Arora and Kohli, 2018). The disturbance in the Aravalli is worrying as studies show that groundwater levels in Gurgaon are depleting at a rate of 0.73 m annually (Malik and Rajeshwari, 2015).
Further, the Aravalli have for years acted as a barrier for checking the movement of sand from the Thar Desert in Rajasthan to the Delhi-NCR region, Haryana and Western Uttar Pradesh. The degradation of the hills has resulted in a situation where while in 1972-75 they stretched out over 10,462 sq km, in 2018, they have been reduced to mere 6,116 sq km. In all, 12 breaches in the Aravalli have opened up extending from Ajmer to Jhunjhunu (Rajasthan) and the Mahendragarh district in Haryana. Another study, conducted by the Wildlife Institute of India found sand dunes have been found in villages close to Gurgaon and Delhi, raising the chances of more dust from the deserts of the Thar blowing into the cities (Arora and Kolhi, 2018).
There is little doubt that the rampant construction activities and illegal mining taking place in the Aravalli are major factors responsible for their continual degradation. The disappearance of these ranges will bring about a loss of not just biodiversity and scenic beauty, but will severely affect the water supply in cities that are already facing threats of extreme groundwater depletion. In the absence of strict implementation of the various court orders that have banned indiscriminate mining and construction activities in the Aravalli and strict regulation of legal mining, the loss of these ranges cannot be countered. It is, therefore, pertinent to oversee the activities being undertaken in this extremely fragile area to ensure their protection.
Arora S. and S. Kohli, 2018. How shrinking Aravallis opened giant gateway for dust pollution in Delhi-NCR, The Times of India, September 15.
Arora S., 2017. Why the Arvallis must live to make Gurgaon liveable, The Times of India, June 16.
Craddock P. T., I. C. Freestone, L. K. Gurjar, K. T. M. Hedge and V. H. Sonawane, 1985. Early Zinc Production in India, Mining Magazine, 152(1): 45-49.
Malik S. and Rajeshwari, 2015. Estimation of Ground Water Resource of Gurgaon District, Haryana, Journal of Land Management, 14(1):25-36.
Basant R.and K. E. Mothi Kumar, 2013. Mapping of Mining Areas in Aravalli Hills in Gurgaon, Faridabad and Mewat Districts of Haryana using Geo-Informatics Technology,International Journal of Remote Sensing & Geoscience, 2(1):1-8.
Rana R., 2013. Groundwater Water Information Booklet Fatehabad District, Haryana, Central Ground Water Board, Available at: https://bit.ly/2znibaH
Sharma S., 2018. Ray of hope for Aravalli range, The Tribune, October 6.
Srivastava R., 1998. Mining of Cooper in Ancient India, Indian Journal of History of Science, 34(3).
Supreme Court of India, 2018. M. C. Mehta vs Union of India, W.P. (C.) No. 4677 of 1985 with W.P. (C.) No. 202 of 1995, Available at: https://bit.ly/2P8UBt6
Thakur J., 2017. Saving Aravallis: Delhi’s green lung facing desertification, Ridge cover down 40%, Hindustan Times, September 26.