Aravalli lesson: Law must factor in ecology
As climate risks deepen, we cannot afford a policy framework that separates legal neatness from ecological function
The controversy over the redefinition of the Aravalli Hills has reignited a crucial question about how India protects its living landscapes. In late November 2025, the Supreme Court accepted a new uniform definition that recognises only those landforms rising at least 100 metres above the local terrain as the Aravalli hills and sets spatial criteria to group them into ranges. The court is set to revisit its order against the backdrop of critics arguing that the change could strip legal protection from over 90% of existing Aravalli hills, most of which are lower ridges and hillocks that underpin essential ecological services.
The developments raise a pressing policy question: Can an elevation-based legal definition adequately protect a landscape whose value lies in its ecological function and, if not, what must India do differently?
First, legal definitions must align with ecological function rather than rigid geometric thresholds. Scientific terrain mapping, using digital elevation models, remote sensing and GIS, aims to bring clarity to regulatory frameworks. Yet the Aravalli system is not a series of isolated peaks. Of more than 12,000 mapped hills at least 20 metres high, only about 1,048 (8.7%) exceed the 100-metre cut-off now used in legal classification.
These low-elevation ridges, often between 20 and 50 metres, act as the first line of defence against desertification, modulate wind and dust flows, and play a disproportionate role in shaping local microclimates and soil stability. Scientific and ecological research shows that terrain features that do not cross a height threshold can still exert significant influence on hydrology and ecosystem connectivity, yet under the new legal rubric, they risk being overlooked or deemed expendable. It is not enough for the law to map hills; it must account for the functions those hills perform.
India must, therefore, adopt functional ecological criteria, for example, recharge potential, slope integrity, vegetation continuity and corridor connectivity- alongside elevation. Only then will legislation protect what truly matters in environmental and climate resilience, rather than what is convenient to measure. Without this shift, a vast proportion of an active ecosystem risks becoming “invisible” to law even as it continues to regulate dust, climate and water flows.
Second, climate adaptation and disaster-risk planning must explicitly integrate these functional landscapes. Climate models and risk assessments for droughts, floods and heatwaves increasingly depend on accurate representations of surface processes such as runoff modulation, infiltration dynamics and slope stability. When features are excluded from legal definitions, they tend also to disappear from planning datasets, groundwater recharge maps and urban resilience strategies. This is especially concerning given that the Indo-Gangetic plains and Delhi-NCR are projected to experience more intense heatwaves, dust storms and erratic rainfall patterns by mid-century under climate change scenarios. The Aravallis historically slowed desertification and regulated local micro-climates, a role that over time will only grow in importance. Future climate risk frameworks should mandate that landscapes with measurable hydrological influence be incorporated into flood zonation, urban heat action plans and drought preparedness strategies irrespective of arbitrary height thresholds.
Third, the fundamentals of water security in rural India must be foregrounded in any Aravalli policy. The Aravalli hills act as a vast, fractured rock sponge that captures monsoon rain and recharges groundwater aquifers. Central Ground Water Board assessments have documented groundwater levels falling by more than 60% over two decades in parts of Haryana and Rajasthan, driven by over-extraction, loss of vegetation and disruption of natural recharge zones.
In regions such as southern Haryana, 26 out of 28 administrative blocks are categorised as “over-exploited”. Recharge rates in the broader Aravalli landscape are estimated at 2 million litres per hectare per year under intact conditions. Policies that reduce the legal protection of these recharge landscapes risk accelerating groundwater decline, threatening agricultural productivity, domestic water access and industrial supply across a region where extraction commonly exceeds replenishment by more than 300%.
Delhi-NCR’s environmental resilience also hinges on how we treat the Aravallis. The region is home to more than 46 million people and routinely registers some of the highest ambient particulate matter concentrations globally during winter months, with PM2.5 episodes reaching hazardous levels. While anthropogenic combustion sources are a dominant factor, the natural topographic barrier that the Aravallis provide dampens dust transport from the Thar Desert and regional plains. Research and monitoring indicate that when lower ridges are breached or removed, dust loads can spike by 4–6 times, exacerbating poor air quality episodes. As urban heat islands intensify under climate change projections, the contribution of natural green and rocky buffers to moderating surface temperatures becomes even more critical. Urban planning for the Delhi-NCR must treat the Aravallis as essential natural infrastructure, integrating them into master plans, disaster management frameworks and climate adaptation strategies.
To be sure, the government has clarified that “no new mining permits” will be granted in core and ecologically sensitive areas of the Aravalli under the new regime, and that protections will apply to roughly “90% of the landscape”, including much of the legally defined range. But legal protection in name must translate into ecological protection in practice. Projections from land-use assessments warn that if current trends in degradation, deforestation and fragmentation continue, up to 22% of the Aravalli area could be lost by 2059, with around 2,630 sq km potentially subject to mining and allied pressures, even as climate stress intensifies.
This debate on the Aravallis offers a broader lesson for India’s environmental future. As climate risks deepen, we cannot afford a policy framework that separates legal neatness from ecological function.
Aparna Roy is fellow and lead, climate change & energy, ORF. The views expressed are personal
