Using DInSAR, airborne LiDAR, and archival air photos to quantify landsliding and sediment transport

We demonstrate the ability of coupled remote sensing tools to characterize large, slow‐moving landslides in the Eel River catchment, northern California. From a stack of ALOS interferograms, we identified 5 large (>1 km long) landslides that exhibited significant activity from February 2007 to February 2008. For the Boulder Creek earthflow, we used orthorectified air photos taken in 1964 and unfiltered airborne LiDAR flown in 2006 to map the displacement of trees growing on the landslide surface. Combining those displacement orientations with stacked DInSAR data, we observed average downslope velocities of 0.65 m yr −1 through the central transport zone of the landslide. Given landslide depth estimates, minimum sediment transport and denudation rates are estimated to be 4100 m 3 yr −1 and 1.6 mm yr −1 , respectively. Our results demonstrate the highly erosive role of large, slow‐moving landslides in landscape evolution and suggest that the superposition of dense, ephemeral gully networks and rapidly moving zones within the landslide may facilitate delivery of slide‐mobilized sediment into adjacent fluvial channels.