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Connectivity of earthquake-triggered landslides with the fluvial network: implications for landslide sediment transport after the 2008 Wenchuan earthquake

Li, G.; West, A.J.; Densmore, A.L.; Hammond, D.E.; Jin, Z.; Zhang, F.; Wang, J.; Hilton, R.G.

Connectivity of earthquake-triggered landslides with the fluvial network: implications for landslide sediment transport after the 2008 Wenchuan earthquake Thumbnail


Authors

G. Li

A.J. West

D.E. Hammond

Z. Jin

F. Zhang

J. Wang

R.G. Hilton



Abstract

Evaluating the influence of earthquakes on erosion, landscape evolution, and sediment-related hazards requires understanding fluvial transport of material liberated in earthquake-triggered landslides. The location of landslides relative to river channels is expected to play an important role in postearthquake sediment dynamics. In this study, we assess the position of landslides triggered by the Mw 7.9 Wenchuan earthquake, aiming to understand the relationship between landslides and the fluvial network of the steep Longmen Shan mountain range. Combining a landslide inventory map and geomorphic analysis, we quantify landslide-channel connectivity in terms of the number of landslides, landslide area, and landslide volume estimated from scaling relationships. We observe a strong spatial variability in landslide-channel connectivity, with volumetric connectivity (ξ) ranging from ~20% to ~90% for different catchments. This variability is linked to topographic effects that set local channel densities, seismic effects (including seismogenic faulting) that regulate landslide size, and substrate effects that may influence both channelization and landslide size. Altogether, we estimate that the volume of landslides connected to channels comprises 43 + 9/−7% of the total coseismic landslide volume. Following the Wenchuan earthquake, fine-grained (<~0.25 mm) suspended sediment yield across the Longmen Shan catchments is positively correlated to catchment-wide landslide density, but this correlation is statistically indistinguishable whether or not connectivity is considered. The weaker-than-expected influence of connectivity on suspended sediment yield may be related to mobilization of fine-grained landslide material that resides in hillslope domains, i.e., not directly connected to river channels. In contrast, transport of the coarser fraction (which makes up >90% of the total landslide volume) may be more significantly affected by landslide locations.

Citation

Li, G., West, A., Densmore, A., Hammond, D., Jin, Z., Zhang, F., …Hilton, R. (2016). Connectivity of earthquake-triggered landslides with the fluvial network: implications for landslide sediment transport after the 2008 Wenchuan earthquake. Journal of Geophysical Research: Earth Surface, 121(4), 703-724. https://doi.org/10.1002/2015jf003718

Journal Article Type Article
Acceptance Date Mar 26, 2016
Online Publication Date Apr 22, 2016
Publication Date Apr 22, 2016
Deposit Date Mar 31, 2016
Publicly Available Date Oct 22, 2016
Journal Journal of Geophysical Research: Earth Surface
Print ISSN 2169-9011
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 121
Issue 4
Pages 703-724
DOI https://doi.org/10.1002/2015jf003718
Public URL https://durham-repository.worktribe.com/output/1415618

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Published Journal Article (Advance online version) (4.2 Mb)
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Copyright Statement
Advance online version Li, G., West, A.J., Densmore, A.L., Hammond, D.E., Jin, Z., Zhang, F., Wang, J. & Hilton, R.G. (2016). Connectivity of earthquake-triggered landslides with the fluvial network: implications for landslide sediment transport after the 2008 Wenchuan earthquake. Journal of Geophysical Research - Earth Surface, Article first published online: 22 APR 2016, 10.1002/2015JF003718 (DOI). To view the published open abstract, go to http://dx.doi.org and enter the DOI.






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