Debris Flow Modeling for Langsi Landslide: A Case Study of Alaknanda Valley, Uttarakhand

Landslides are naturally occurring hazards that occur frequently in the tectonically and geologically complex Himalayan terrain, which entails landslide hazard assessment using varied numerical simulation approaches. The present study attempts to conduct site-specific debris flow modeling using Rapid Mass Movement Simulation (RAMMS) software for a debris flow located at Langsi along the NH-58 highway in the Alaknanda Valley, Uttarakhand. The model works on a voellmy friction approach, and a release area needs to be defined on the ALOS PALSAR Digital Elevation Model (DEM), which is the mandatory primary input in the model. The calibrated values for the dry-Coulomb friction (μ) taken as 0.4 and viscous-turbulent coefficient (ξ) taken as 300 m/s2 were obtained after a no. of hit and runs. The geophysical parameters such as maximum velocity, height, pressure, and flow momentum were obtained as 25.75 m/s, 14.61 m, 1326.21 kPa, and 86.47 m2/s, respectively, and further, the line profile graphs were plotted for both height and velocity to know the variation of these parameters along the profiles. The research would aid in suggesting necessary geotechnical engineering measures and helping simulate and understand the actual cause, process, and mechanism of landslides.