The kinematic process and geomorphological impact of the Jiaobunong paleolandslide dam in the Eastern Himalayan Syntaxis
摘要
The Eastern Himalayan Syntaxis is a high denudation zones, with mass flow events occurring frequently. The Jiaobunong paleolandslide (JPL) river blocking event is a typical prehistoric event that can be identified by special topography and upstream lacustrine sediments. This study applies the topographic reconstruction technique to revive the paleolandscape prior to the landslide occurrence, and further adopts discrete element software to invert the kinematic process of the JPL. The numerical simulation results reveal the whole landslide process to last for 130 s, with a peak average velocity of 51 m/s after sliding for 45 s. Following this, a large deposit with an extremely thick front of approximately 260 m was formed. The landslide material not only blocks the Lulang River, but also climbs onto the opposite platform, forming a large dammed lake upstream with a maximum area of 7.12 km2. On-site investigation showed that the initial morphology of the JPL dam was altered by river incision, so parameter sensitivity analysis was used to obtain the optimal combination of morphological parameters. The JPL is particularly prominent in regional landforms due to the rapidly shrinking topography, which controls the formation of a slope-break knickpoint in the river profile. The formation of the knickpoint can be attributed to the topography control and landslide morphology of the region. This study can provide guidance for landslide prediction, disaster emergency response, and ecological restoration in similar regions.