Karakoram highway is diverse in geography, geology, and tectonics and the region is facing the world’s deadliest threat of this century known as “climate change”. The current project aimed at quantifying the debris flow hazard at the catchment to regional scale using field investigations combined with remote sensing, GIS, UAV-based RAMMS modeling, and Flow-R modeling. The current research considers not only the debris flow hazards along the KKH but also provides the climatic projections for precipitation and temperature and consequently debris flow hazard, risk, and vulnerability for early (2020-2040), mid (2040-2060) and end century (2060-2080) scenarios.

The entire region is divided into two parts starting from Besham to Bunji section and Bunji to Khunjerab section with approximately 250km stretch lengths respectively. The first step was to create a database of debris flowing along the KKH. This task was achieved through extensive field surveys. Debris flows were identified based on their morphology, geology, and topographic characteristics. Local people were also involved to know the historical perspective of the gully. A total of 60 gullies are identified from Besham to Bunji and 71 gullies are identified from Bunji to Khunjerab section. Using the 12.5x12.5m DEM, catchments were delineated in the entire study area. Debris flow and non-debris flow catchments were differentiated and presented in diagrams. The next step was to categorize the catchments into debris flow, debris flood and flood catchments. This task was achieved through the morphometric assessment of the catchments by developing the relation between catchment length, width, slope, relief and relief ratio parameters. Out of 60 gullies, there were 31 & 49 debris flow, 36 & 17 debris flood and 4 & 5 were flood catchments respectively along two sections. Grain size distribution analysis of 29 massive debris flow gullies, the higher gravel and sand percentage is reported causing higher erosive power, mobility and impact force. Climatic projections show increasing spatiotemporal temperature and precipitation trends in the region. Hazard, Risk and vulnerability levels are high for early, mid and end century climatic scenarios. UAV based RAMMS modeling predicted the runout scenario perfectly for an active debris flow gully. Flow-R predicted enhanced debris flow susceptibility at the regional scale.