Nguy cơ sạt lở cao ở các vị trí đèo dốc | VTV24

Key Concepts

• Sạt lở (Landslides)
• Mưa lớn kéo dài (Prolonged heavy rain)
• Đèo dốc (Mountain passes/slopes)
• Yếu tố địa chất (Geological factors)
• Yếu tố thủy văn (Hydrological factors)
• Yếu tố nhân sinh (Anthropogenic factors)
• Áp lực lỗ rỗng (Pore water pressure)
• Động năng (Kinetic energy)
• Dấu hiệu cảnh báo sớm (Early warning signs)
• Lũ quét (Flash floods)
• Lũ bùn đá (Debris flows)
• Nghẽn dòng (Blockages)
• App cảnh báo sạt lở (Landslide warning app)

Summary of Landslide Risks and Prevention Measures in Central Vietnam

This discussion addresses the severe landslide risks in Central Vietnam due to prolonged heavy rainfall, exacerbated by geological, hydrological, and anthropogenic factors. The recent incident on Khánh Lê pass, where a rockfall killed six people, highlights the urgent need for awareness and preventative measures.

Current Landslide Risks and Vulnerable Areas

Professor Đỗ Minh Đức, from the University of Science, Vietnam National University, Hanoi, identifies that following a period of heavy rain in late October and a new wave of intense rainfall, landslide incidents have become severe across Central Vietnam. While mountain passes and slopes are particularly vulnerable, many national highways are also experiencing widespread and frequent landslides.

High-risk routes include:

• Hồ Chí Minh Highway
• Trường Sơn Đông Highway
• National Highway 40B
• National Highway 14E
• National Highway 14D
• National Highway 24
• National Highway 24C

In addition to national highways, numerous provincial and district roads are also severely affected by landslides.

Factors Contributing to Increased Landslide Risk

Professor Đức outlines several key factors contributing to the heightened risk of landslides, often occurring without prior warning:

• Anthropogenic Factors:
  • Excessive excavation: Many road sections involve cutting slopes to excessive heights with steep gradients on the positive embankment (ta-luy dương).
  • Proximity to watercourses: Some negative embankments (ta-luy âm) are built too close to the operational range of water flows, leading to instability.
• Geological Factors:
  • Tectonic activity: This can cause rock and soil to fracture and become highly heterogeneous.
  • Thick weathered crust: A well-developed weathered layer on slopes increases susceptibility.
  • Rock type composition: The presence of large, hard bedrock boulders within the slope material is a significant concern. When these slide from a great height, they possess high kinetic energy and lethality, a factor often overlooked in landslide prevention.
• Hydrological Factors:
  • Rainwater infiltration: Surface water seeping into slopes increases pore water pressure, reduces shear strength, and triggers landslides.

Early Warning Signs and Public Awareness

Professor Đức emphasizes the importance of recognizing early warning signs to mitigate risks:

• Warning signs: Always pay attention to existing warning signs on roads, especially on dangerous mountain passes.
• Unusual phenomena: Before a landslide, there may be unusual sounds or abnormal changes in water flow.
• Travel advisories: Given the prolonged heavy rain, it is strongly recommended to minimize travel on dangerous mountain passes, particularly at night.

Recommendations for Residents and Authorities

In the context of ongoing heavy rainfall, Professor Đức provides prioritized recommendations:

• For residents near slopes and streams:
  • Monitor for cracks: Observe for cracks on slopes.
  • Watch for vegetation changes: Look for leaning trees or unusual ground displacement (heaving or subsidence).
  • Check for blockages: Regularly inspect river and stream banks for blockages caused by landslides or fallen trees.
  • Report and clear blockages: Immediately report any detected blockages to local authorities and assist in clearing them.
• For authorities:
  • Road closures: Implement road closures on mountain passes during heavy rainfall.
  • Controlled re-opening: Only allow traffic to resume after ensuring the safety of the routes.
  • Dual threat awareness: Be aware of both large-scale landslides and flash floods/debris flows caused by blockages.

Technological Tools for Early Warning

Professor Đức highlights a technological solution developed by his research group:

• "Sạt lở Việt Nam" App: This free application is available on Google Play Store and Apple App Store.
  • Data updates: Provides landslide data updated every 20 minutes.
  • Multi-hazard alerts: Warns about various natural disasters including heavy rain, large-scale landslides, and flash floods/debris flows.
  • Near real-time information: Allows users to zoom into specific areas and receive timely, near real-time information about natural disaster events in their vicinity.

Conclusion

The ongoing heavy rainfall in Central Vietnam poses significant landslide risks. Understanding the contributing factors, recognizing early warning signs, and utilizing available technological tools like the "Sạt lở Việt Nam" app are crucial for public safety. Adhering to the guidance of authorities and prioritizing personal safety by avoiding hazardous areas during periods of heavy rain are paramount.