Joshimath, a town in the Himalayas, recently experienced significant land subsidence, causing large cracks in roads and over 868 civil structures. This study uses time-series synthetic aperture radar (SAR) interferometry-based PSInSAR approach and high-resolution Planet datasets to monitor land subsidence. The line of sight (LOS) land subsidence velocity for the Joshimath region in 2022–2023 varies from −89.326 to +94.46 mm/year. The highest land subsidence occurred in the north-western part of the town. The study investigates the causative factors and provides recommendations for future development policies in the region.
Introduction
The Himalayan mountain range is highly susceptible to natural disasters like land subsidence, earthquakes, and landslides due to tectonic activity. Recent events in Joshimath have highlighted the risks posed by these phenomena. The town has seen significant land subsidence, resulting in infrastructure damage and posing a risk to residents. The study uses advanced remote sensing techniques to monitor and analyze land subsidence in the region.
Causes of Land Subsidence
1. Tectonic Activity: The collision between the Indian and Eurasian tectonic plates creates significant stress on the ground, leading to land subsidence.
2. Earthquakes: Frequent seismic activities exacerbate the subsidence process.
3. Landslides: Triggered by earthquakes, heavy rainfall, deforestation, and large-scale construction projects.
4. Anthropogenic Activities: Infrastructural development and inadequate drainage systems contribute to soil compaction and ground destabilization.
Consequences
- Infrastructure Damage: Cracks in roads and buildings, collapse of structures.
- Disruption of Services: Transport, communication networks, water, and electricity supplies are affected.
- Social Impact: Evacuation of homes, social insecurity among local communities, and potential loss of life.
Remote Sensing Techniques Used
1. PSInSAR (Persistent Scatterer Interferometry): Utilizes multi-temporal Sentinel-1 SAR datasets to monitor land subsidence.
2. Planet Datasets: High-resolution imagery for feature tracking land displacement analysis.
- Highest Land Subsidence (2022–2023): North-western part of Joshimath with a LOS land subsidence velocity of +60.45 mm/year to +94.46 mm/year.
- Moderate to High Subsidence: North and central regions with subsidence of +10.45 mm/year to +60.45 mm/year.
- Expansion: South-west part with subsidence of 84.65 mm/year to −13.13 mm/year.
- Rapid Subsidence: South-east part with subsidence of −13.13 mm/year to −5 mm/year.
Recommendations
- Controlled Development: Regulate infrastructural projects to prevent further destabilization.
- Improved Drainage Systems: Implement effective drainage solutions to manage water flow and prevent soil compaction.
- Regular Monitoring: Use advanced remote sensing techniques for continuous monitoring of land subsidence.
- Community Awareness: Educate local communities about the risks and safety measures related to land subsidence.
Conclusion
Joshimath's sinking is primarily attributed to a combination of tectonic activity, anthropogenic factors, and inadequate infrastructure planning. Advanced remote sensing techniques like PSInSAR and high-resolution imagery are essential for monitoring and managing land subsidence. Implementing the recommended policies can help mitigate risks and promote sustainable development in the region.
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