New Delhi: The Kamla Nehru Ridge, a lush green expanse with minimal concrete, is a haven for peacocks, monkeys, mongooses, boars, and reptiles. Yet paradoxically, it has emerged as the hottest part of Delhi, regularly recording the highest maximum temperatures in the city.
By late afternoon and evening, the heat becomes palpable at the meteorological observatory inside the premises of the regional seismological centre, popularly known as “Bhuchaal Bhawan”. The Ridge observatory recorded the city’s highest maximum temperatures among manned stations on all three days this week — 44.6 degrees Celsius on Monday, 46.5 degrees Celsius on Tuesday, and 45.8 degrees Celsius on Wednesday. In contrast, Safdarjung, Delhi’s base weather station and benchmark for official readings, recorded temperatures at least a degree lower on each of those days.
Unique Geography of the Ridge
AK Singh, the scientific officer stationed at the observatory, explained that the Ridge consistently behaves differently from the rest of Delhi. “Generally, the Ridge observatory often records the highest maximum temperature, lowest minimum temperature, as well as the maximum precipitation,” Singh said. “It’s because of its unique geography. It’s a forest, but with rocky terrain. The rocks absorb heat, thereby increasing the temperature; they also radiate the heat. Later they cool down quite quickly, thus impacting the minimum temperatures. Due to greenery, the rain in the area is also often high,” he added as he accessed the Stevenson screen to take a temperature reading.
The Ridge is one of five manned weather observatories maintained by the India Meteorological Department (IMD) in the capital, with readings recorded every three hours. The other manned observatories are in Safdarjung, Palam, Ayanagar, and Lodhi Road.
Ecological Degradation and Invasive Species
Scientists say the Ridge’s paradoxical heat is tied not only to its rocky terrain but also to ecological degradation caused by invasive vegetation. According to Faiyaz A Khudsar, scientist-in-charge of DDA biodiversity parks programme, the landscape of this final spur of the Aravali range has long been dominated by Prosopis Juliflora, or vilayati kikar, an invasive species that disrupts the area’s natural cooling mechanisms, failing to regulate moisture and ambient temperatures effectively.
“Prosopis Juliflora’s ecological function, such as water budgeting, is very abnormal, meaning, it takes far higher amounts of water from the soil than it releases in the atmosphere. It has little to no impact on ambient temperatures. Native vegetation, on the other hand, has characteristics that regulate ambient temperatures,” Khudsar said.
Khudsar added that a systematic ecological restoration programme to remove Prosopis Juliflora and replace it with native vegetation has been initiated. This effort aims to restore the Ridge's natural cooling functions and mitigate the urban heat island effect in the area.
Implications for Urban Planning
The Ridge’s case highlights the complex interplay between geography, ecology, and urban microclimates. While green spaces are generally expected to cool cities, the type of vegetation and underlying terrain can significantly influence local temperatures. The ongoing restoration programme underscores the importance of native species in maintaining ecological balance and regulating climate.
