Geomorphological hazards along the Karakoram Highway: Khunjerab Pass to the Gilgit River, northernmost Pakistan

Abstract

The Karakoram Highway traverses one of the most rapidly rising mountain ranges on earth. A combination of earthquakes, glacial erosion, river incision, periglacial action and an unpredictable input of monsoonal rains make it a region of very high geodynamic activity. Since its completion, the Karakoram Highway has been subject to damage and disruption by rockfall, sliding of rock and debris, debris flow, mudflow, dry powder flow, flash flooding by water and torrent gravels, basement undermining by abstraction, subsidence and frost heaving. The road surface is regularly damaged by rockfall impact, floods and frost shattering. Landslides and debris flows have been evaluated using field mapping and gravimetric techniques, and a systematic hazard survey has been completed over a distance of more than 200 km from the Khunjerab Pass (Pakistan - China border) to Gilgit. The largest scale threats are semi-continuous mass movements on oversteepened cliffs of uncemented late-Pleistocene till, and the meltwater streams of some large glaciers. The highest frequency hazards are alluvial and mudflow fan progradation, together with talus fan sliding.