Road construction, hill cutting driving Western Ghats landslides: Study

Researchers found nearly 72 per cent of landslides in the Western Ghats occurred within one kilometre of roads, highlighting the impact of human-induced terrain changes

Beyond extreme rainfall and the growing impact of climate change, human-induced landscape changes, particularly road construction, hill cutting and conversion of native forests into commercial plantations, are emerging as major drivers of landslides in India’s ecologically fragile Western Ghats, a new scientific study has found.

 

The study, conducted by researchers from two universities in India and Brazil, revealed that nearly 72 per cent of documented landslides occurred within one kilometre of road networks in the region, indicating that road cutting, slope excavation, blasting, drainage alteration and associated infrastructure expansion play a decisive role in destabilising hill slopes.

 

One of the prominent mountainous areas with great ecological and economic significance, the Western Ghats region (WGR) is highly prone to landslides that are prevalent during the monsoon season. The researchers used advanced machine-learning models to assess landslide susceptibility across the 1,600-km-long Western Ghats stretching through Gujarat, Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu.

 

 

They studied an inventory of 444 recorded landslides and an equal number of non-landslide locations between 2004 and 2024 to identify the most influential factors behind slope failures across the mountain chain.

 

“Rainfall remains a critical triggering mechanism, but our findings clearly show that many slopes are already under stress because of anthropogenic disturbances. Roads, unscientific hill cutting, drainage obstruction and land-use transformation are creating conditions where even moderate rainfall can trigger catastrophic slope failures,” said Manoranjan Mishra, head of the geography department at FM University, Odisha.

 

Steep slopes, characterised by abrupt changes in elevation, increase landslide hazard in the region, Mishra said. The regional geology consists of weathered and fractured Precambrian crystalline rocks such as charnockites, khondalites and gneisses, which render slopes susceptible to failure. Chemical weathering and rock fragmentation produce regolith and debris that accumulate in slope wedges. Landslide hazard increases when slope materials become saturated and overloaded during the rainy season. Tectonic activity, particularly in the southern Western Ghats, also acts as a landslide trigger, he said.

 

The findings come at a time when recurring landslides in the WGR are often attributed solely to cloudbursts, extreme monsoon events and broader climate variability. However, the new research suggests that while intense rainfall may act as the immediate trigger, human modification of mountain terrain is significantly amplifying the underlying vulnerability of slopes.

 

“We observed a clear spatial correlation between landslide clusters and transportation corridors in many vulnerable districts. Districts such as Raigad, Kodagu, Idukki and the Nilgiris have been identified as highly vulnerable, primarily due to drivers like deforestation, slope modification, unplanned road construction and intense monsoon precipitation. Nearly three out of every four landslides recorded in our database were located close to roads,” said Rajkumar Guria, a researcher.

 

The researchers analysed landslide behaviour across diverse geological and climatic settings in the Western Ghats — from the basaltic terrains of Maharashtra to the charnockite and gneissic formations of Kerala and Tamil Nadu. The team also generated high-resolution susceptibility maps for the entire mountain system by integrating 22 environmental, geological, topographical, climatic and anthropogenic variables.

 

Apart from altered infrastructure, the study found that geological structures such as fault lines and shear zones, elevation, slope gradient and earthquake sensitivity continue to influence landslide occurrence. Rapid land-use change was also identified as another major factor increasing slope instability. The conversion of natural forests into plantations such as rubber, tea and coffee, as well as terracing for agriculture, construction of retaining structures and obstruction of natural stream channels, were found to significantly alter hydrological balance and soil cohesion.

 

“Native forests have deep root systems that bind soil and regulate water infiltration. When these forests are replaced by monoculture plantations or fragmented by human interventions, slope resilience declines substantially. This creates highly fragile landscapes vulnerable to collapse during intense precipitation,” said Richarde Marques da Silva, another researcher.

 

Calling for urgent policy intervention, the researchers recommended stricter geotechnical assessments before road construction in hill regions, scientific drainage management, restoration of degraded forest slopes, regulation of plantation expansion in ecologically sensitive zones and integration of machine-learning-based susceptibility maps into district-level disaster management plans.

 

“Our analysis shows that landslides in the Western Ghats are not merely natural disasters. Human interventions often intensify these natural vulnerabilities by disturbing already fragile terrain. If infrastructure development continues without terrain-sensitive planning, slope stabilisation measures and ecological restoration, the frequency and intensity of such disasters may rise further under a changing climate,” Mishra warned.