Mitigating Flood and Landslide Risks | 18 Sep 2025

Source: IE  

Why in News?

The current monsoon has brought unusually intense rainfall to hilly states such as Uttarakhand and Himachal Pradesh, exacerbating the incidence of landslides and pushing river systems to perilous levels, thereby heightening risks to both lives and infrastructure.

What Factors Increase the Vulnerability of Hilly Regions to Floods and Landslides?

• Steep Slopes and Gravity: Water flows down steep slopes much faster than on flat land, preventing infiltration. This causes water to quickly accumulate in streams and rivers, leading to rapid-onset flash floods.
  • For instance, landslides in Mandi, Kullu, Dharali, Tharali, and Jammu.
• Geology and Soil Type: Many young mountain ranges (like the Himalayas) are geologically active and made of fractured, weak, or weathered rocks that are easily dislodged.
  • Mountain soils are often thin and lack deep root systems, making them prone to being washed away.
    • Frequent landslides in Darjeeling and Sikkim are due to weak rock formations and fragile soils.
• Hydrological Factors: A valley funnels rainfall into a narrow stream or river, and the steep gradient with high energy flow gives water strong erosive power, which erodes riverbanks and slopes, making floods worse.
  • For instance, Alaknanda and Mandakini river valleys in Uttarakhand frequently witness flash floods.
• Trigger Factors: Continuous rain or intense cloudbursts saturate soil, reduce friction, and trigger landslides, flash floods, and debris flows.
  • Sudden temperature rise or rain on snow causes snowmelt, releasing large water volumes, saturating the ground, and flooding streams.
  • E.g., For the season (June-September 2025), the northwestern region has received more than 30% surplus rainfall.
• Human-Induced Factors: Road cutting, construction on steep slopes, blocked natural drainage, unsustainable agriculture, and overgrazing destabilize slopes, increasing the risk of landslide.
  • The Joshimath land subsidence (2023), linked to unregulated construction, highlights human-induced vulnerability.

How does Climate Change Increase Flood and Landslide Vulnerability?

• Increased Extreme Rainfall Events: A warmer atmosphere holds more moisture (≈7% per 1°C), causing intense rainfall and cloudbursts, which trigger flash floods as the ground cannot absorb water fast enough, overwhelming streams and rivers.
  • Climate change disrupts monsoon patterns, causing droughts followed by intense rain, where dry, hardened soil reduces absorption, increasing runoff, flood, and erosion risk.
• Glacial Lake Outburst Floods (GLOFs): Rising temperatures cause glacier retreat and the formation of unstable lakes dammed by moraines, which can breach in GLOF events, releasing massive water and debris, leading to catastrophic flooding downstream.
  • The 2023 South Lhonak GLOF (Sikkim) destroyed the Rs 16,000 crore Chungthang hydropower project, caused silting in the Teesta river, and increased downstream flood risk.
• Permafrost Thaw: In high-altitude hilly regions, rising temperatures thaw permafrost, causing slope destabilization, rockfalls, and landslides, which add debris to rivers and increase flood risks.
• Increased Wildfires: Climate change makes hilly areas hotter and drier, increasing wildfires that destroy vegetation, create water-repellent soil, and cause fast-moving debris flows when rain hits.
  • For instance, the India State of Forest Report (ISFR) 2023 showed that Uttarakhand alone recorded 5,351 forest fire incidents between November 2022 and June 2023.

What Measures can be Adopted to Mitigate the Vulnerability of Regions to Floods and Landslides?

• Environmental Measures: Afforestation and Reforestation with native trees and Van Panchayats empower communities to bind soil, absorb rainwater, and protect forests. 
  • Contour trenching, terrace farming, and check dams slow runoff, allow infiltration, trap sediment, and reduce erosive power.
• Engineering Measures: Rock bolts, soil nails, retaining walls, and debris flow barriers/screens stabilize slopes and prevent rocks and debris from reaching roads or settlements.
  • Channel improvement, diversion channels, and sediment traps increase river capacity, redirect excess water, and capture silt and debris to reduce flood risk.
  • Urban flood resilience can be enhanced through proper drainage, sponge city models, and rainwater harvesting.
• Policy Measures: Enforce carrying capacity studies, stringent land use planning, and hazard zone identification to restrict construction on steep slopes, riverbeds, and floodplains, relocate vulnerable settlements, and implement stringent building codes.
  • Develop robust early warning systems integrating weather forecasts, rainfall data, and river levels, and support them with community sirens and drills to ensure timely evacuation to safe zones.
• Economic & Financial Measures: Establish dedicated disaster risk reduction budgets for states and districts.
  • Shift to Parametric Insurance Models for quick payouts based on rainfall/flood-level triggers (avoiding lengthy claims).

Conclusion

Hilly regions are inherently vulnerable due to steep slopes and fragile geology. However, human activities like unsustainable construction and deforestation have severely amplified this risk. Effective mitigation requires an integrated approach, aligning with the Sendai Framework for Disaster Risk Reduction (2015–30), by combining stringent land-use policies, ecological restoration, engineering solutions, and community-based early warning systems.