Chapter 8 - Multiple landslide-damming episodes

Abstract

The natural blockage of river channels by landslide debris gives rise to a range of potentially adverse processes including complete or partial damming, backwater inundation and sedimentation, catastrophic outbursts of impounded lake waters and downstream river aggradation following dam failure. Most reports portray landslide dams as short-lived and hazardous landforms that often require immediate mitigation using engineering solutions. Despite a growing body of research informed by increasingly detailed remote sensing and field data, we still lack tools for reliably predicting the stability, or timing of failure, of landslide dams. In this chapter, we augment a number of detailed reviews on landslide dams by focussing on recent insights on the synchronous and region-wide emplacement of several dozens to hundreds of landslide dams and their consequences on water and sediment fluxes. Such multiple landslide-damming episodes are rarely addressed in the literature, though they create distinct challenges for both research and hazard mitigation. These challenges include appraisals of how to distinguish from amongst multiple coevally formed dams those that are most hazardous; suitable engineering solutions for stabilising landslide dams; management of massive sediment pulses – and their risks – in the wake of landslide dam failures and the notion of a palaeoseismological interpretation of clusters of coeval landslide dams.