Disaster Management · TEE · papers
Q3A · Illustrate with neat sketch any 2 types of Landslides and their specific mitigation m…
2024-12-10 · Semester V final
Actual older TEE paper · 100 marks · Q1 compulsory; any four of Q2–Q7
Q3A. Illustrate with neat sketch any 2 types of Landslides and their specific mitigation measures. Also explain the same in detail. [10 marks]
Answer
Definition. A landslide is downward movement of rock, debris or earth under gravity. Its movement may be falling, toppling, sliding, spreading or flowing.
| Type | Movement | Illustration |
|---|---|---|
| Fall | Material detaches and falls through air. | Rockfall from a steep cliff. |
| Topple | A block rotates forward around a pivot or base. | Jointed rock columns lean and overturn. |
| Slide | Material moves along a recognisable slip surface. | Rotational slide on a curved surface or translational slide on a plane. |
| Flow | Material deforms and moves like a flowing mass. | Water-saturated debris flow. |
| Spread | Extension and lateral movement, sometimes over a weak layer. | Ground spreading associated with liquefaction. |
Why a slope becomes unstable
- Rain infiltration raises pore-water pressure and can reduce effective resistance.
- River erosion or road cutting removes support at the slope toe.
- Earthquake shaking adds destabilising forces.
- Weak or weathered rock and unfavourably oriented joints create possible failure surfaces.
- Deforestation, added loads, excavation and poor drainage can increase susceptibility.
Cracks, tilting trees or poles, new seepage and small falls can indicate instability, but no single sign reliably predicts every landslide. Report suspected movement and follow local evacuation advice; do not enter an active slide to investigate.
Mitigation matched to mechanism
Rotational slide: investigate the curved slip surface, reduce infiltration, manage loading and toe support and restrict unsafe development. Topple: investigate fractured blocks, control water and use suitable specialist anchoring/support or exclusion and catch measures. The same retaining wall is not a universal solution for both.
