Remote sensing investigation and simulation of landslide-induced river blocking and dam-break flood on the opposite bank of Mindu in the upper Jinsha River

This paper is the result of landslide remote sensing investigation and numerical simulation.

Objective This study aims to reveal the overall instability risk of the landslide on the opposite bank of Mindu in the upper Jinsha River, attributed to its poor slope integrity and pronounced deformation, and to assess the potential chain of landslide, river blocking, dam−break flood, as well as its impacts on major engineering works and downstream safety.

Methods A combined approach of dynamic monitoring using multi−source, multi−temporal remote sensing imagery and numerical simulation was employed to systematically analyze the deformation characteristics and stability of the landslide. The processes of river blocking and dam−break flood under both natural and heavy rainfall conditions were simulated.

Results The landslide has a volume of approximately 682.5×10⁴ m³, classifying it as a large−scale landslide. The sliding mass consists of debris−filled soil, while the sliding bed is composed of mica−quartz schist. Deformation can be traced back to 1965, spanning nearly 60 years, and the landslide is currently in a creep−sliding deformation stage. The failure mode is a retrogressive progressive failure, and the landslide can be divided into two deformation zones. Under natural conditions, Zone I is in an unstable state, while Zone II ranges from unstable to basically stable. Simulations indicate that under natural conditions, failure of Zone I would result in a sliding mass movement duration of approximately 50 s with a maximum velocity of about 55 m/s, forming a landslide dam with an estimated height of 77 m and a dammed lake capacity of approximately 1.17×10⁸ m³. The resulting flood peak discharge at the Lawa hydropower station dam site would be about 1875 m³/s, with a maximum flood crest height of approximately 8 m. Under heavy rainfall conditions, the entire landslide would become unstable, with an estimated dam height of 88 m and a lake capacity of 1.48×10⁸ m³. The flood peak discharge at the Lawa dam site would reach about 2690 m³/s, with a maximum flood crest height of about 11 m.

Conclusions The landslide poses a high river blocking risk upon failure. It is recommended to employ an integrated space−air−ground monitoring system for continuous tracking, so as to ensure the safe construction of major engineering projects in the upper Jinsha River and to safeguard the transportation infrastructure along the river as well as the safety of local communities and property.