--- title: "Problems of Lesser Himalaya with mitigation" subject: "Engineering Geology II" chapter: 2 key: "semester_4/engineering_geology_ii:lesser-himalaya-problems" source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/lesser-himalaya-problems site: BCT Engineering --- # Problems of Lesser Himalaya with mitigation Engineering Geology II · Chapter 2: Engineering Geology in Himalayas - Asked in: 2072 Magh, 3 marks; 2073 Bhadra, 2 marks; 2076 Baisakh, 2 marks; 2071 Magh, 2 marks; 2068 Magh, 3 marks (asked 5 times) - Video: [Himalaya | Engineering Geology |](https://www.youtube.com/watch?v=OPFrUBwcto8) — B.E. Civil ( Purbanchal University) - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/lesser-himalaya-problems - Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-2 ## Question Describe the major engineering geological problems of the Lesser Himalaya zone with their mitigation measures. ## Short answer The Lesser Himalaya faces landslides, rock fall, weak foliated rocks, karst cavities, and seismic hazards. Mitigation includes gentle cut slopes, retaining structures, drainage, rock bolts, shotcrete, bio-engineering, grouting, and earthquake-resistant design. ## Answer The **Lesser Himalaya** lies between the MBT in the south and the MCT in the north. It is made of phyllite, slate, schist, quartzite, limestone, dolomite and some granite, and is intensely folded and faulted. #### Major problems and mitigation | Problem | Cause | Mitigation | |---|---|---| | Landslides and slope failure | Weak phyllite, schist, steep slope, heavy monsoon rain, road cutting | Gentle cut slopes, retaining walls, gabions, breast walls, bio-engineering, benching | | Rock fall and toppling | Closely jointed hard rocks (quartzite, dolomite) | Rock bolts, wire mesh, shotcrete, catch ditches | | Weak rocks in foundations and tunnels | Phyllite, slate, schist have foliation and low shear strength; squeezing | Proper support (steel ribs, rock bolts, shotcrete); alignment across the strike of foliation | | Karst / solution cavities | Limestone, dolomite | Grouting, cut-off, avoid reservoir over limestone | | Seismic activity | Nearness of the MBT and MCT | Earthquake resistant design, avoid fault zones | | Erosion and gully formation | Deforested slopes, residual soil | Check dams, drainage, plantation | | High sediment | Weathered soft rock | Desanding, catchment treatment | | Groundwater and springs drying | Fractured rock, deforestation | Recharge ponds, spring protection | General mitigation: detailed geological mapping, good surface and sub-surface drainage, avoiding deep cuttings, slope monitoring and early warning. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Between which thrusts does the Lesser Himalaya lie? A. MFT and MBT B. MBT and MCT C. MCT and STDS D. STDS and Indus-Tsangpo Answer: B. The Lesser Himalaya lies between the MBT in the south and the MCT in the north. (Key point: Zone limits) 2. Which measures reduce rock fall in closely jointed quartzite and dolomite? A. Rock bolts, wire mesh, shotcrete and catch ditches B. Steeper cuts C. Removing drainage D. Check dams only Answer: A. Rock bolts, mesh, shotcrete and catch ditches hold or catch falling blocks. (Key point: Rock fall mitigation) 3. What is the mitigation for solution cavities in limestone? A. Plantation B. Grouting, cut-off and avoiding reservoirs over limestone C. Gabions D. Desanding Answer: B. Karst leaks are treated by grouting and cut-offs or avoided by site choice. (Key point: Karst) 4. What combination causes landslides in the Lesser Himalaya? A. Strong granite and flat slopes B. Weak phyllite/schist, steep slope, heavy monsoon and road cutting C. Dry climate and sandy soil D. Deep clay and low rainfall Answer: B. Weak rocks, steep slopes, monsoon rain and road cutting together trigger slope failures. (Key point: Landslide cause) ## Related in Engineering Geology II - [Mitigation of geological problems in Himalaya](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Ahimalaya-problems-mitigation) — Engineering Geology II, chapter 2 - [Engineering geological problems of Siwalik zone](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Asiwalik-problems) — Engineering Geology II, chapter 2, asked 4× - [Problems of Lesser Himalaya and Terai](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Alesser-himalaya-terai-problems) — Engineering Geology II, chapter 2, asked 5× - [Mitigation of geological hazards](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Ageohazard-mitigation-measures) — Engineering Geology II, chapter 5 - [Geological hazards of Higher Himalaya](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Ahigher-himalaya-hazards) — Engineering Geology II, chapter 2 - [Problems of Higher and Tethys Himalaya](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Ahigher-tethys-problems) — Engineering Geology II, chapter 2 ## Related in other subjects - [Lesser Himalaya zone in detail](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Alesser-himalaya-zone-in-detail) — Engineering Geology I, chapter 7 - [Discontinuities and engineering problems in Nepal Himalaya](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Adiscontinuities-and-engineering-problems-in) — Engineering Geology I, chapter 7 - [Engineering geological problems in tectonic divisions](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aengineering-geological-problems-in-tectonic) — Engineering Geology I, chapter 7, asked 2× - [Tectonic division and Lesser Himalaya geology](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atectonic-division-and-lesser-himalaya) — Engineering Geology I, chapter 7