Journal - Role of vegetation in slope stability: Case studies of forested slopes in the Mahabharat Range, Nepal

Role of vegetation in slope stability: Case studies of forested slopes in the Mahabharat Range, Nepal

Yajna Prasad Timilsina and Ram Prasad Sharma

Institute of Forestry, Pokhara Campus, Tribhuvan University, Pokhara, Nepal

Prakash Paudel

Kabeli Energy Limited, Buddhanagar, Kathmandu

Jour. Nepal Geol. Soc., Vol. 44, 2012, 59-66


Abstract

The study was aimed at identification of the role of vegetation and soil in slope instability in the Mahabharat Range of Nepal. The bio-physical informations were collected from the Laxmi Narayan, Lasti Berenata, Sambot and Jamune Dhaba Community Forest of Mahabharat Range of western Nepal. The landslides are in pelitic rocks suchs as phyllite, gritty phyllite and schists. The pelitic rocks are highly weathered forming sandy loam texture. The studied landslides fall in Shorea robusta- and Schima walichii-dominated forests with major tree species like Shorea robusta (Sal), Schima walichii (Chilaune), Alnus nepalensis (Uttis), Pinus roxburghii (Loth Salla) and Lagerstroemia parviflora (Botdhainro). The dominant shrub species are Osbeckia nepalensis (Angeri small), Maesa chisia (Bilaune), Rosa brunonii (Bainselu) and Woodfordia fruticosa (Dhairo). Pogonotherum crinitum (Muse Kharu), Chrysopogon sp. (Titepati), Imperata cylindrical (Siru), Bidens pilosa (Kuro), Anaphisis controta (Bukiphul), Onychyium uoponium (Chille unyu), Eupatirium odoratum (Banmara) and Reinwardtia indica (Pyauli) are major herb/grasses species. The surplus load of vegetation (tree species) in the studied landslides with groundwater activities were found to have significant role in slope instability instead forested area. As the slip plane is deeper than 3.4 m, tree roots has no anchoring role for stabilization of the studied landslide.

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