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Landslide hazard zonation mapping and debris flow modelling in Nainital, Uttarakhand
* 1 , 2 , * 2 , 2
1  Symbiosis Institute of Geoinformatics, Symbiosis International University, Pune, Maharashtra, 411016, India
2  Department of Geosciences, Indian Institute of Remote Sensing, Indian Space Research Organization, Dehradun, 248001, India


Landslide is one of the most devastating natural hazards in the Uttarakhand Himalaya, India. Though it has many active and old hotspots, we have focused on Nainital district only in this study considering recent events and challenges. Although available literature exhibits many such case studies from this area, landslip and landslide events which took place, off late, remains to be one of the major burning issue in this area, albeit. Out of many landslide hazard zonation methods, it is felt appropriate to apply Analytical Hierarchy Process (AHP) in this area which takes cues mainly from measurements through pair wise comparisons of causative factors and relies on the judgement of the experts to derive priority scales to enable stake holders adopting a multi criteria decision making approach. Many thematic layers were, hence, considered for this purpose which includes slope, aspect, hillshade, land use and land cover (LULC), normalised difference vegetation index (NDVI), lineament, geomorphology, geology etc. These raster inputs were derived mainly from high resolution multispectral, open source DEM and other ancillary data sets. Landslide hazard zonation map, thus produced, were successfully validated on the ground. This kind of map for the whole district holds promise for the stake holders to assess potential high hazard zones and plan to provide remedial measures and thereby supporting mitigation mechanism in case of any future potential hazard. However, considering that present day research in the field of landslides has evolved beyond hazard zonation map, it was decided to develop debris flow models at few critical but strategically important sites by numerical simulation technique. This debris flow models are mainly to be fed space-borne and ground based geological and geotechnical inputs. The simulated result provides spatial variation of different geophysical parameters like pressure, momentum, height and velocity in the affected run-out zone. These outputs provide crucial information on real time landslide hazard mitigation and support to the development of early warning systems.

Keywords: Landslide hazard zonation mapping; debris flow modelling; Analytical Hierarchy Process; Landslide inventory.