Experimental study of landslide-induced flooding in open channels

摘要

There are an increasing number of high dams constructed on valley rivers with steep bank slopes in Southwest China. An appropriate combination of hydroclimatic and geotechnical conditions and reservoir operation may favor the occurrence of large-scales landslides. Large-scale landslides produce landslide dams in rivers, which may block the stream flow and cause inundation upstream, and subsequently fail and lead to devastating flooding downstream. The need for accurate assessment of the potential threat to the society and the safety of hydraulic constructions has been well recognized. However, current understanding of the physical processes of landslide-induced flooding continues to be poor due to the complicated nature of the phenomenon, and inevitably reliable methods and tools for evaluation of possible consequences of river-blocking landslides are still missing. This paper presents an experimental study of landslide-induced flooding in open channels. A flume of 80 m × 1.2 m × 0.8 m is deployed, along with an array of ten automatic water-level probes. Tests are carried out over initially fixed beds. For each of a set of constant incoming clear-water flow discharges, a massive body of loose sediments of a variety of sizes is instantly added to the flow through a sediment-feeder at the middle of the flume, simulating a landslide. Water levels are recorded every half a second at ten cross-sections along the channel. The failure of the landslide body is visually observed. The experiments provide useful data resources for understanding landslide-induced flooding and for testing mathematical river models.