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 based on engineering solutions. Despite a growing body of research thanks to increasingly detailed remote sensing and field data, we often lack readily accessible 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 focusing on recent insights into the synchronous and regional-scale emplacement of several dozens to hundreds of landslide dams and their consequences on water and sediment fluxes. Such multiple landslide-damming episodes have been rarely addressed in the literature so far, though they create a number of distinct challenges for both research and hazard mitigation. These challenges include rapid appraisals of how to distinguish from among multiple coevally formed dams that are most hazardous; suitable engineering solutions for stabilizing landslide dams; management of massive sediment pulses—and their risks—in the wake of landslide-dam failures; and the paleoseismological interpretation of clusters of coeval landslide dams.