| Abstract Submission No. | ABS-3.1-0220 |
| Title of Abstract | InSAR-Based Assessment of Extreme Precipitation Induced Landslides in the Western Ghats, India |
| Authors | Deepika Bharti*, Dinesh Kumar Sahadevan, Anand Kumar Pandey |
| Organisation | CSIR-NGRI |
| Address | Research Scholar Hostel-2, CSIR NGRI Hyderabad, Telangana, India Pincode: 500007 E-mail: deepikabharti5295@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | A portion of the Western Ghats in Wayanad, including the Vavulmala and Vellarimala hills in Kerala, is highly susceptible to recurring landslides and debris flows during the monsoon season. The extreme climatic event on 8th August 2019 induced a flash flood in Puthumala (Site-1, 5 pm) and massive landslide in Kavalappara (Site-2, 8 pm), followed by landslides and flash floods triggered by extreme rainfall event on 30th July 2024, at Chooralmala (Site-3, 2:17 am), south of Site-1, impacting the villages of Mundakkai and Vellarimala. These precipitation-driven mass wasting events caused substantial loss of life and property. We used time-series InSAR and precipitation data to detect precursory ground movement around the affected zones. Precipitation records show that Sites-1 and 2 received their maximum daily rainfall in 24 years on 8th August 2019. Longer-term trends indicate rising cumulative annual rainfall and increasing maximum daily precipitation at all sites, reflecting a gradual intensification of extreme rainfall events. Time series InSAR analysis reveals average LOS movements of -25 cm/yr, -6 cm/yr, and -17 cm/yr at Sites-1, 2, and 3, respectively. Notably, InSAR also captures localized uplift at Site-1 (+10 cm/yr), Site-2 (+40 cm/yr), and at Site-3 (+18 cm/yr), indicating hydrological loading and slope destabilization prior to failure. Extreme rainfall was the primary trigger at all three sites. Flash floods followed landslides at Sites-1 and 3 due to their riverine locations, while at Site-2, anthropogenic activities such as agriculture on steep, concave slopes worsened landslide severity. These findings highlight the urgent need for continuous monitoring of the metastable slopes as precursory study to plan slope stabilization, land-use regulation, and early-warning systems. In addition to ground-based monitoring, meteorological data and time-series InSAR can provide actionable intelligence, enabling authorities to proactively manage and mitigate landslide hazards across the Western Ghats regions. |
| Keywords | Landslides, InSAR, Wayanad, Slope stability, Extreme precipitation |