New Delhi, March 11 Built-up areas in India's Aravalli range have increased by 53 percent, resulting in a 13.8 percent increase in average soil loss per year between 2017 and 2024, even as forest cover has increased in the country's oldest mountain range over that period, a study has found.
Researchers from O.P. Jindal Global University and the Indian Institute of Technology Kharagpur assessed land use and land cover patterns between 2001 and 2021 and found that steep slopes, susceptible soils, and mining areas are strongly associated with erosion hotspots.
The increased soil erosion in the Aravalli Mountain System, despite a significant increase in afforestation, highlights that local conservation efforts cannot compensate for massive land conversion, according to findings published in the journal Geographies.
The Aravallis are primitive mountains where soils are deep and ecosystems are intricate and delicately balanced, the researchers said.
The range is among India's most mineral-rich mountain systems, hosting a wide range of metallic and non-metallic minerals and serving as a cornerstone of India's mineral resource base.
The team analyzed moderate-resolution data recorded between 2001 and 2020 to identify long-term trends, with high-resolution data from 2017 and 2024 selected to accurately measure erosion trends. The two years represent current and divergent meteorological conditions, they said.
The study revealed "a clear growth in overall forest cover at a broad spatial scale."
However, fine-scale measurement showed erosive processes and a sharp growth in built environments, along with a subsequent depopulation of rangelands and croplands.
This trend is similar to that seen in ancient mountain systems worldwide, the researchers said.
"LULC (land use and land cover) has changed rapidly, with built-up areas increasing by 53 percent at the expense of rangelands and croplands. These changes resulted in a 13.8 percent increase in the mean annual soil loss between 2017 and 2024, from 1.59 to 1.81 t/ha/yr (tonnes per hectare per year), while forest cover has increased over that period, as is evident in this study," the authors wrote.
The conversion of semi-natural vegetation surfaces to built, impervious surfaces has a direct, negative effect on the land's natural defense mechanisms, they said.
The team added that a lack of forest does not afflict landscapes, but through the disintegration and transformation of the larger, stabilizing land matrix, downstream ecosystems are affected.
Human-caused erosion of the landscape was found to be accompanied by an increase in climatic erosivity between 2017 and 2024.
The interdependence of human activity and climate change, in which human activity increases exposure and climate change increases hazards, is characteristic of the contemporary degradation of vulnerable ecosystems across the globe, the authors said.
"As a result, a 13.83 percent increase in mean soil erosion rates became a direct and foreseeable effect," they said.
"These findings highlight the fact that local conservation benefits, such as afforestation, can be overwhelmed by large, unsustainable land conversion processes," the team wrote.