Identifying post-earthquake debris flow hazard using Massflow

dc.contributorAalto Universityen
dc.contributor.authorHorton, Alexander J.en_US
dc.contributor.authorHales, Tristram C.en_US
dc.contributor.authorOuyang, Chaojunen_US
dc.contributor.departmentDepartment of Built Environmenten
dc.contributor.groupauthorWater and Environmental Eng.en
dc.contributor.organizationCardiff Universityen_US
dc.contributor.organizationChinese Academy of Sciencesen_US
dc.description.abstractCatastrophic debris flows are common after large earthquakes and pose a significant risk for recovering communities. The depositional volume of these large debris flows is often much greater than the initiation volume, suggesting that bulking of the flow plays an important role in determining their volume, speed, and runout distance. Observations from recent earthquakes have driven progress in understanding the relationship between triggering rainfall events and the timing of post-earthquake debris flows. However, we lack an adequate mechanism for quantifying bulking and applying it within a hazard context. Here we apply a 2D dynamic debris flow model (Massflow) that incorporates a process-based expression of basal entrainment to understand how debris flow bulking may occur within post-earthquake catchments and develop hazard maps. Focussing on catchments in the epicentral area of the 2008 Mw 7.9 Wenchuan Earthquake, we first parameterised the model based on a large debris flow that occurred within the Hongchun catchment, before applying the calibrated model to adjoining catchments. A model sensitivity analysis identified three main controls on debris flow bulking; the saturation level of entrainable material along the flow pathway, and the size and position of initial mass failures. The model demonstrates that the difference between small and very large debris flows occur across a narrow range of pore-water ratios (λ). Below λ = 0.65 flows falter at the base of hillslopes and come to rest in the valley bottom, above λ = 0.70 they build sufficient mass and momentum to sustain channelised flow and transport large volumes of material beyond the valley confines. Finally, we applied the model across different catchments to develop hazard maps that demonstrate the utility of Massflow in post-earthquake planning within the Wenchuan epicentral region.en
dc.description.versionPeer revieweden
dc.identifier.citationHorton, A J, Hales, T C & Ouyang, C 2019, ' Identifying post-earthquake debris flow hazard using Massflow ', Engineering Geology, vol. 258, 105134 .
dc.identifier.otherPURE UUID: ebd5bf43-fa42-4183-9d61-1fd2acf7ada9en_US
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dc.publisherElsevier Science B.V.
dc.relation.ispartofseriesEngineering Geologyen
dc.titleIdentifying post-earthquake debris flow hazard using Massflowen
dc.typeA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessäfi