Disaster management strategy for potential slide zones of Kumarkhera in Narendra Nagar township of Tehri Garhwal district, Uttarakhand, India
Anthropogenic activity in this area in the form of widening of road, blasting, stone quarrying and construction of multi-storied cemented structures should be abandoned. Complete ban should imposed on permanent and or temporary constructions on the either side of causeway as the permanent constructions for commercial purpose in the upslope of causeway are not only narrowing the passage of natural drains but are also obstructing the flow of surface runoff of the upslope area (see Plates 6-8) and temporary structures on the either side of causeway will be on a high risk (of being washed away) during rainy season. Cleaning of existing scuppers in the area and construction of new scuppers should be taken up and use of polythene bags should be banned not only in this area but in all other hill towns as the polythene waste does not decompose and blocks scuppers and drains (constructed to flash out water) and hence impedes the surface flow of excess rain water. This in turn leads to seepage of water and increase in pore water pressure that finally increases the sliding force. Sewage holes (septic tanks), in the area should be replaced by sewage lines, to flush out the sewage, along with the household wastewater. Large sewage tanks should be constructed for this purpose at some distance so that the household wastewater is not allowed to percolate into the hill slope. Conclusion Climatic factors such as heavy rainfall during monsoon season (June to September) and geological factors, namely jointed and fractured rocks with some seepage zones, fragile slope that may have witnessed mass wasting in the past together with the seismicity in the area are some of the natural factors fostering slope instability. Anthropogenic Disaster management strategy 367 Plate 8. A field view of construction over the body portion of old slide and consequent overloading of fragile hill slope and narrowing of natural course of small drainages at Kumarkhera
DPM 19,3 368 intervention in the form of blocking or diversion of natural drainage system and overloading of hill slope (due to ill conceived construction of houses) when combined with the cumulative effect of natural factors renders the area prone to potential mass wasting activity in the future. Seismic shocks, heavy rains or prolonged spells of rainfall may suddenly trigger large-scale subsidence and slides in this area. Immediate structural and non-structural mitigation measures should be under taken to avoid the risk posed to the small hamlet of Kumarkhera. Tehsil/Block Disaster Management committee, municipality and NGOs, should be involved in sensitization and awareness creation in order to persuade the local population to desist from construction of multistoried houses and rigorous cutting of slope for construction activity. Border Road Organization and Public Works Department can jointly initiate structural mitigation measures in the area. References Brunsden, D. and Jones, D.K.C. (1984), “The geomorphology of high magnitude low frequency events in the Karakoram Mountains”, in Miller, K. (Ed.), International Karakoram Project, Cambridge University Press, Cambridge, MA, pp. 343-88. Ives, J.D. (1987), “The theory of Himalayan environmental degradation: its validity and application challenged by recent research”, Mountain Research and Development, Vol. 7 No. 3, pp. 189-99. Naithani, A.K., Prasad, C., Bist, M.P.S. and Kumari, G. (1997), “Landslide zonation and geo-environmental appraisal along Main Central Thrust zone in Mandakini valley”, Garhwal Himalaya, India, Himalayan Geology, Vol. 18, pp. 135-43. Owen, L.A. (1991), “Mass movement deposits in the Karakoram Mountain: their sedimentary characteristic, recognition and role in Karakoram landform evolution, Z”, Geomorphol, Vol. 35 No. 4, pp. 401-24. Owen, L.A., Sharma, M. and Bigwood, R. (1996), “Landscape modification and geo-morphological consequences of the 20 October 1991 earthquake and the July-August 1992 monsoon in the Garhwal Himalaya”, Z. Geomorphol, Vol. 103, pp. 359-72. Owen, L.A., Benn, D.L., Derbyshire, E., Evans, D.J.A., Mitchell, W.A., Thompson, D., Richardson, S., Lloyd, M. and Holden, C. (1995), “The geomorphology and landscape evolution of the Lahul Himalaya, Northern India”, Z. Geomorphol, Vol. 39, pp. 145-74. Raina, B.N. (1978), “A review of stratigraphy and structure of lesser Himalaya of Uttar Pradesh and Himanchal Pradesh”, in Saklani, P.S. (Ed.), Tectonic Geology of the Himalaya, Today and Tomorrow’s Printers and Publishers, New Delhi, pp. 79-112. Thakur, V.C. (2004), “Active tectonics of Himalayan frontal thrust and seismic hazard to Ganga Plain”, Current Science, Vol. 86 No. 11, pp. 1554-9. Uniyal, A. (2004), “Landslides at Karnaprayag: another Uttarkashi in the making?”, Current Science, Vol. 87 No. 8, pp. 1031-3. Uniyal, A. (n.d.), “Prognosis and mitigation strategy for major landslide prone areas: a case study of Varunavat Parvat landslide in Uttarkashi township of Uttarakhand (India)”, Disaster Prevention and Management: An International Journal. Uniyal, A. and Prasad, C. (2006), “Disaster management strategy for mass wasting hazard prone Naitwar Bazar and surrounding areas in Upper Tons valley in Uttarkashi district, Uttaranchal (India)”, Disaster Prevention and Management: An International Journal, Vol. 15 No. 5, pp. 821-37.