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Problems of Siwalik and Higher Himalaya

Short answer

Siwalik problems are landslides, erosion, and weak rocks. Higher Himalaya faces rock falls, snow avalanches, GLOFs, unstable moraines, tunnel rock burst and squeezing, earthquakes, and frost action, with difficult high-altitude construction.

Describe the main engineering geological problems of the Siwalik and Higher Himalayan zones of Nepal.

Siwalik zone

Composed of weakly cemented sandstone, mudstone and conglomerate.

  • Landslides, gully erosion and debris flow due to weak rock and steep slope.
  • Swelling and slaking of mudstone; poor aggregate.
  • Active tectonics along MFT and MBT; earthquakes.
  • Heavy sediment load and floods carried to the plains.

Higher Himalaya zone

Composed of high-grade metamorphic rocks: gneiss, schist, migmatite, quartzite and granite, with very high relief and glaciers.

  • Rock fall, rock avalanche and large rockslides on steep, jointed slopes.
  • Snow avalanche, glacier hazards, GLOF and permafrost thaw.
  • Unstable moraines and glacial deposits that produce debris flows.
  • Tunnel problems: high overburden gives rock burst and squeezing in shear zones; high in-situ stress.
  • Earthquakes along the MCT and active faults.
  • Frost action and very cold climate affect construction.
  • Access and construction are difficult at high altitude.

✓ Answer checked by Claude Opus 5.5 (high effort)

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