An Aravalli lesson: Law must factor in ecology

The controversy over the redefinition of the Aravalli Hills has reignited a crucial question about how India protects its living landscapes.

- Aparna Roy

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 cutoff 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.