RECONSTRUCTION OF TANGNI DEBRIS FLOW ALONG NH 58, UTTARAKHAND INDIA THROUGH ELECTRICAL RESISTIVITY IMAGING

Abstract:

Debris flow is one of the major mass movements that threat the environment, infrastructure and human activities in the Indian Himalaya terrains which needed to be well investigated and understood. The basic information regarding the triggering mechanisms of this phenomenon is therefore necessary. Majority of the debris flow in Indian Himalayas are triggered due to extreme rainfall and cloud burst. The destructive power of debris flow is defined by its mobility and the material volume involved through the process as well as the final depositional material volume and thickness. In this present work, the application of Electrical resistivity imaging has been applied to study the subsurface information of Tangni debris flow along NH 58 Garhwal Himalaya India. The materials present at the source zone have been estimated by using Electrical resistivity imaging and thereafter the debris flow modeling has been performed using numerical simulation. The profile lines were strategically at the source zone of the slope in order to determine the characteristics of the subsurface materials of the zone. The interpretation of the Electrical Resistivity Tomography (ERT) shows that the slope material is made up of three material layers namely: Colluviums material, underlined by dolomite. The rupture surface of the slope is located between the loss colluviums materials and the weathered dolomite. The results obtained from the ERT helps in the reconstruction of the slope which shows that the depth of the colluviums materials at the source zone has an average of 50m thickness. Further the thickness of the colluviums materials was used in the numerical simulation to assess the impact of the failure of the slope in terms of volume and run out.

Keywords: Debris slope, Electrical Resistivity Tomography (ERT), Numerical simulation, Tangni