Before SC call for ‘experts’, a panel sought more studies for method to define Aravallis

The sub-committee of experts from these three institutions was required to submit its assessments to a larger panel, led by the Union Environment Secretary, which was constituted on the orders of the Supreme Court.

The larger nine-member panel comprised bureaucrats from the Environment ministry, the four states where Aravalli spans, and representatives of Supreme Court’s Central Empowered Committee, FSI and Geological Survey of India.

According to records, in the TSC, the FSI presented its work delineating Aravallis based on the 3-degree-slope formula in 15 districts of Rajasthan in 2010-11.

The GSI, however, proposed to identify the Aravalli Hills as “Proterozoic fold belt…forming a linear series of alternate hills and valley” with a slope of 8 % (4.57 degree) and a height of at least 30 metres.

FSI and SoI, records show, were not in agreement on having a “hard threshold” based on either slope or elevation to define Aravallis. It was discussed in the sub-committee report that the nature of hills varies across terrains, and thus applying a strict slope and height criteria uniformly may not be practical.

In conclusion, the TSC reported that “all the tested methods produce various proportions of false positives and false negatives. Sometimes the habitations were getting included, while in the same cases plateaus were getting excluded. Sometimes hills having slopes less than 8% (4.57 degree) were getting excluded, thereby excluding the foothill portion.”

With this, the TSC recommended further work to finalise a method for delineating the hills which would “provide reproducible results associated with landform modelling”.

Eventually, though, the 100 metre-definition was based on the elevation and slope criteria, to have an operational definition which could be applied uniformly in the context of mining.

As reported by The Indian Express, the ministry-led panel’s recommendation of 100-metre definition was opposed by the Supreme Court’s Central Empowered Committee and the amicus curiae after an internal assessment of its digital relief data by the FSI cautioned that the 100-metre definition would exclude 90% of the Aravalli hills.

The SC’s suo motu intervention took note of these concerns when it ordered re-examination of the matter by domain experts, especially regarding any potential threat of degradation to areas excluded by the new definition. For the record, the TSC had already looked at a number of these issues.

During discussions on the TSC’s submissions, the larger ministry-led panel also sought comments from the stakeholder states – Rajasthan, Gujarat, Delhi and Haryana.

While Rajasthan, Gujarat and Haryana broadly consented to the eventual definition recommended to the SC, the Haryana government had a different view.

It had argued that in addition to the elevation criterion of 100 metres from local relief, an age-based geological criterion may be incorporated in the definition. The Centre-led panel, however, did not agree to this.

It said that while the geological origin of the hills’ formation provides scientific context, it could not be used for regulatory and operational purposes, as that required readily verifiable parameters such as elevation and protection of supporting slopes.

In its December 29 order, the SC bench headed by CJI Surya Kant said that a high-powered committee of domain experts must examine areas that are excluded from protection under the new definition of Aravallis, and whether such excluded areas risk being degraded.

The Centre-led panel had recommended to SC to define Aravalli Hills as any landform at an elevation of 100 metre or more above local relief or ground level, and Aravalli ranges as two or more hills within 500 metre from each other.