Impacts of landslide dams on mountain morphology

Landslide dams can influence mountain-valley morphology significantly in the vicinity of the dam sites, as well as upstream and downstream. The effects are: (1) impoundment of lakes that result in changes in stream gradients, (2) deposition of lacustrine and deltaic sediments in these impoundments that causes changes in surficial morphology and geologic materials upstream from the dams, (3) diversions of stream channels at the and near the sam sites, (4) formation of avulsively-shifting channels downstream from the dams by the introduction of high sediment loads from erosion of landslide deposits or sediments in the landslide-dammed lakes, and (5) secondary landslide activity along the shores of impounded lakes due to rapid drawdown when the dam fails. Often, by construction of channel spillways or outlet tunnels human remedial efforts affect the longevity of landslide dams and the impoundments, and thus influence the long term effects of these natural features on mountain valley morphology.