Debris flow in indian himalaya: A threat to emerging infrastructure

Abstract

The present study aimed to understand the debris flow characteristics in view of frequent extreme rainfall events, expansion of road networks, tourist influx, and population pressure in the NW & Central Himalaya. Notably, majority of the human settlements, roads, bridges, buildings, and even protection measures in the NW & Central Himalaya do not take into consideration such debris flow impact scenario despite a history of debris flow disasters. The Voellmy-Salm rheology dependent dynamic runout simulation method was used to determine the debris flow pressure and velocity regime in 9 debris flow locations belonging to different litho-tectonic conditions. Results revealed that the debris flow pressure and velocity in these 9 studied debris flows might reach up to 3000 kPa and 20 m/s, respectively. The debris flow pressure and velocity of these orders have the potential to damage the protection measures and infrastructures, which have also been observed in other hilly terrains. The sensitivity analysis was carried out at a range of input parameters by considering 729 possible simulations and debris flow pressure and velocity are found to follow relatively better corelation until ~ 250 kPa flow pressure and ~ 15 m/s velocity thresholds. The influence of slope topography on the debris flow characteristics is also observed in the form of amplification of flow pressure and velocity at concave portions. The rapid development of road network in the NW & Central Himalayan region and its subjectivity to potential debris flow risk is also discussed.