Investigation of hill slope stability and mitigation measures in Sikkim Himalaya

Dr. M.S. Rawat, Dr. Varun Joshi, Dr. D.P Uniyal, Dr. B.S. Rawat

Abstract


Survey of India toposheets, cloud free satellite data and field survey with the help of handheld GPS were carried out along major road of Sikkim for landslide investigation. The geological and geotechnical analysis  carried out for the major trouble shooting spots in the eastern Himalayas along National Highway (NH-31A), North Sikkim Highway (NSH) and Singtam-Dikchu road, Gangtok-Nathula Highway, and a perennial trouble spot at Bojecck  on Jorthang-Hilly state highway  undertaken to understand the factors affecting triggering of  landslides in the respective areas. The study identified lithology or rock type, structure of the bedrocks (i.e. orientation of the rock foliations and faults), excessive rainfall and human interference like diversion of streams as the main factors triggering the landslides in the region. The areas with weak rocks which are susceptible to weathering, i.e. schist, mudstone, and slate and the areas, where rock and and/or fault foliations are favorable with respect to the road cuts, are found to be vulnerable to landslide. During continuous heavy rainfall, the weathering process is accelerated reducing schists and mudstones into silts and fine sands, and subsequent washout fine materials triggers landslides. Rainfall threshold study carried out for Bakthang slide using rainfall data for the year 2010 and minimum threshold for landslide initiation was 35mm/day. In the Bojeck slide the suggested slope mitigation measures include diversion of run-offs, plugging of cracks and crevices, construction of filters and horizontal drains at different elevations along the slopes to prevent washout of fines and safe passage of the water, rock bolting, avoiding human interference and judicious alignment of the roadways.

Keywords


Geospatial technology, landslide, Rainfall threshold and Sikkim Himalaya

Full Text:

PDF

References


Acharyya S.K., "The Daling Group. Its Nomenclature, Tectono-stratigraphy and the Structural Grain: With Notes on Their Possible Equivalents," Geological Survey of India, Special Publication, Vol. 22, 1989, pp. 5-13.

Aleotti, P., (2004). A warning system of rainfall-induced shallow failure. Engineering Geology 73, 247-265.

Anbalagan R., "Landslide Hazard Evaluation and Zonation Mapping in Mountainous Terrain," Eng. Geol., Vol. 32, 1992, pp. 269-277.

Caine, N., (1980). The rainfall intensity–duration control of shallow landslides and debris flows. Geografiska Annaler 62A, 23-27.

Catlos E.J., Harrison T.M., Kohn M.J., Grove M., Ryerson F.J., Manning C.E., and Upreti B.N., "Geochronologic and Thermobarometric Constraints on the Evolution on the Main Central

Crozier, M.J., (1997). The climate-landslide couple: a southern hemisphere perspective. In: Matthews, J.A., Brunsden, D., Frenzel, B., Glaeser, B., Weiss, M.M. (Eds.), Rapid mass movement as a source of climatic evide.

Ghosh S., Paul C., Sarkar N.K. and Bhattacharya A., "Geotechnical Evaluation of Lanta Khola Debris Flow on North Sikkim Highway, North District, Sikkim, An Area for Future Site-Specific Deterministic Probing," J. Engg. Geol., Vol. 29, 2002, pp. 141-147.

Joshi, V., Rawat, M.S., Sharma, A.K., Kumar, K. and Panda, A.K. (2011).Traditional knowledge of natural disaster mitigation and ethno medicine practices in Himalaya with special reference to Sikkim. Indian Journal of Traditional Knowledge, Vol 10(1).pp 198-206.

Joshi, V., Singh M., Sharma, A. K., Kumar, K. (2010).Landsliding an environmental problem in Sikkim Himalaya, a study. Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP). Vol 18. pp 117-122.

Neogi S., Dasgupta S., and Fukuoka M., "High P-T Polymetamorphism, Dehydration Melting, and Generation of Magmatites and Granites in the Higher Himalayan Crystalline Complex, Sikkim, India," J. of Petrology, Vol. 39, No. 1, 1998, pp. 61-99.

Rawat, M. S., Joshi, V. and Sundriyal, Y.P. (2013). Study of rock mass and slope mass rating in the part of East Sikkim Himalaya, India. Indian Journal of Scholarly Research, Vol. 2(I). pp 58-65.

Rawat, M. S., Joshi, V., Rawat, B. S. and Kumar, K. (2011). Landslide movement monitoring using GPS technology: A case study of Bakthang landslide, Gangtok, East Sikkim, India. Journal of Development and Agricultural Economics. Vol. 3(5), pp.194–200.

Rawat, M. S., Rawat, B.S., Joshi, V. and Kimothi, M.M. (2012). Statistical analysis of Landslide in South district, Sikkim, India:using Remote Sensing and GIS. Journal Of Environmental Science, Toxicology And Food Technology. Volume 2 (3), pp 47-61.

Rawat, M. S., Singh, K.K., Joshi, V., and Kumar, K. (2011). Role of rainfall in including landslide- case study of National Highway 31-A , Sikkim Himalaya. Proceedings of regional workshop on Rejuvenation of springs by artificial recharge and catchment area treatment with special reference to rainwater harvesting, Central Ground Water Board, Eastern Region Kolkata. pp. 99-116.

Rawat, M.S., Joshi, V., Sharma, A., Kumar, K. and Sundriyal, Y.P. (2010). Study of Landslides in parts of Sikkim Himalaya. Indian Landslides. Vol . 3(2). pp. 47-54.

Rawat,M.S.,Joshi, V.,Singh,K.K., Kumar, K. and Vishwakarma, S.C.R. (2009). Sikkim Himalaya main bhusakhalan thatha unke roktham ke kuch upay. Rajbhasha Patrika Him Prabha (published by GB Pant Institute of Himalayan Environment & Development, Kosi-Almora), Vol 2, pp 69-74. (in Hindi).

Sengupta A., Gupta S. and Anbarasu K., "Rainfall Thresholds for the Initiation of Landslide at Lanta Khola in North Sikkim, India," J. Natural Hazards, DOI 10.1007/s11069-009-9352-9, 2009 (Published Online).

Varnes, D.J., (1978). Slope movement types and process. In Schuster, R.L., Krizek, R.J. (Eds.), Landslides Analysis and Control. Special Report 176, Transportation Research Board, National Academy of Sciences, Washington, D.C., pp. 12-33.

White, I.D., Mottershead, D.N., Harrison, J.J., (1996). Environmental Systems, 2nd Ed. Chapman and Hall, London. 616 pp.

Wieczorek, G.F., (1996). Landslide triggering mechanisms. In: Turner, A.K., Schuster, R.L. (Eds.), Landslides: Investigation and Mitigation, Transportation Research Board, Special Report 247. National Research Council, Washington, pp. 76 -79.

Heim, A and Gansser, A (1939). Central Himalaya; Geological Observations of the Swiss Expedition 1936, Hindustan Publishing Corporation 73, 245 New Delhi.

Raina, VK. and Srivastava, BS (1980). A reappraisal of the geology of the Sikkimlesser Himalaya, in Stratigraphy and Correlation of lesser Himalayan formation, Bhatia, Hindustan Publishing Corporation,Delhi, pp 201-220 Ray KK (1976). A review of the geology of the Darjeeling– Sikkim Himalayas.: Himalayan Geological Seminar, New Delhi, pp.13–17

Ray, SK (2000). Culmination Zones in Eastern Himalaya; Geological Survey of India Misc. Publ. 55 pp.85–94


Refbacks

  • There are currently no refbacks.