TY - JOUR A1 - Fan, Xuanmei A1 - van Westen, Cees J. A1 - Korup, Oliver A1 - Gorum, Tolga A1 - Xu, Qiang A1 - Dai, Fuchu A1 - Huang, Runqiu A1 - Wang, Gonghui T1 - Transient water and sediment storage of the decaying landslide dams induced by the 2008 Wenchuan earthquake, China JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Earthquake-triggered landslide dams are potentially dangerous disrupters of water and sediment flux in mountain rivers, and capable of releasing catastrophic outburst flows to downstream areas. We analyze an inventory of 828 landslide dams in the Longmen Shan mountains, China, triggered by the M-w 7.9 2008 Wenchuan earthquake. This database is unique in that it is the largest of its kind attributable to a single regional-scale triggering event: 501 of the spatially clustered landslides fully blocked rivers, while the remainder only partially obstructed or diverted channels in steep watersheds of the hanging wall of the Yingxiu-Beichuan Fault Zone. The size distributions of the earthquake-triggered landslides, landslide dams, and associated lakes (a) can be modeled by an inverse gamma distribution; (b) show that moderate-size slope failures caused the majority of blockages; and (c) allow a detailed assessment of seismically induced river-blockage effects on regional water and sediment storage. Monte Carlo simulations based on volumetric scaling relationships for soil and bedrock failures respectively indicate that 14% (18%) of the estimated total coseismic landslide volume of 6.4 (14.6) x 10(9) m(3) was contained in landslide dams, representing only 1.4% of the >60,000 slope failures attributed to the earthquake. These dams have created storage capacity of similar to 0.6x 10(9) m(3) for incoming water and sediment. About 25% of the dams containing 2% of the total river-blocking debris volume failed one week after the earthquake; these figures had risen to 60% (similar to 20%), and >90% (>90%) within one month, and one:year, respectively, thus also emptying similar to 92% of the total potential water and sediment storage behind these, dams within one year following the earthquake. Currently only similar to 0.08 x 10(9) m(3) remain available as natural reservoirs for storing water and sediment, while similar to 0.19 x 10(9) m(3), i.e. about a third of the total river-blocking debris volume, has been eroded by rivers. Dam volume and upstream catchment area control to first order the longevity of the barriers, and bivariate domain plots are consistent with the observation that most earthquake-triggered landslide dams were ephemeral. We conclude that the river-blocking portion of coseismic slope failures disproportionately modulates the post-seismic sediment flux in the Longmen Shan on annual to decadal timescales. KW - Landslide dam KW - Earthquake KW - Magnitude and frequency KW - Sediment budget Y1 - 2012 U6 - https://doi.org/10.1016/j.geomorph.2012.05.003 SN - 0169-555X VL - 171 SP - 58 EP - 68 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lopez-Tarazon, Jose Andres A1 - Batalla Villanueva, Ramon J. A1 - Vericat, Damia A1 - Francke, Till T1 - The sediment budget of a highly dynamic mesoscale catchment the River Isabena JF - Geomorphology : an international journal on pure and applied geomorphology N2 - The paper presents the sediment budget of the Isabena basin, a highly dynamic 445-km(2) catchment located in the Central Pyrenees that is patched by highly erodible areas (i.e., badlands). The budget for the period 2007-2009 is constructed following a methodology that allows the interpolation of intermittent measurements of suspended sediment concentrations and enables a subsequent calculation of sediment loads. Data allow specification of the contribution of each subbasin to the water and sediment yield in the catchment outlet. Mean annual sediment load was 235,000 t y(-1). Specific sediment yield reached 2000 t km(-2) y(-1), a value that indicates very high sedimentary activity, especially in the case of Villacarli and Lascuarre subcatchments, were most badlands are located. The specific sediment yield obtained for the entire Isabena is 527 t km(-2) y(-1), a high value for such a mesoscale basin. Results show that a small part of the area (i.e., 1%) controls most of the catchment's gross sediment contribution. Sediment delivery ratio (ratio between sediment input from primary sources and basin export) has been estimated at around 90%, while in-channel storage represents the 5% of the annual load on average. The high connectivity between sediment sources (i.e., badlands) and transfer paths (i.e., streamcourses) exacerbates the influence of the local sediment production on the catchment's sediment yield, a quite unusual fact for a basin of this scale. KW - Sediment budget KW - Sediment transport KW - Random forests KW - Quantile regression forests KW - River Isabena KW - Ebro basin Y1 - 2012 U6 - https://doi.org/10.1016/j.geomorph.2011.08.020 SN - 0169-555X VL - 138 IS - 1 SP - 15 EP - 28 PB - Elsevier CY - Amsterdam ER -