Landslide mobilization rates: A global analysis and model

Broeckx, Jente; Rossi, Mauro; Lijnen, Kobe; Campforts, Benjamin; Poesen, Jean; Vanmaercke, Matthias

doi:10.1016/j.earscirev.2019.102972

Cited by 56 publications

(41 citation statements)

References 132 publications

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“…This may result in a potential observation bias, with the higher GHD being the result of a longer 'representative time period'. A similar issue was reported with respect to the occurrence of landslides and rockfalls (Broeckx et al, 2018;Broeckx et al, 2020), where landslides observed in arid regions are most likely relicts that are no longer attributable to current environmental conditions. Furthermore, while (semi-)arid regions are often characterized by high gully densities (e.g.…”

Section: Gully Densities Across the Horn Of Africa: A Geomorphic Intesupporting

confidence: 55%

“…Over the past decades, soil and water conservation measures have been implemented at a large scale in the Horn of Africa (Nyssen et al, 2004;Haregeweyn et al, 2015), and significant progress has recently been made in assessing the overall susceptibility of this region to sheet and rill erosion (Haregeweyn et al, 2017;Fenta et al, 2020) and landsliding (e.g. Broeckx et al, 2018Broeckx et al, , 2020. However, no such tools exist for assessing gully erosion.…”

Section: Introductionmentioning

confidence: 99%

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Predicting gully densities at sub‐continental scales: a case study for the Horn of Africa

Vanmaercke

Chen

Haregeweyn

et al. 2020

Earth Surf Processes Landf

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Despite its environmental and scientific significance, predicting gully erosion remains problematic. This is especially so in strongly contrasting and degraded regions such as the Horn of Africa. Machine learning algorithms such as random forests (RF) offer great potential to deal with the complex, often non‐linear, nature of factors controlling gully erosion. Nonetheless, their applicability at regional to continental scales remains largely untested. Moreover, such algorithms require large amounts of observations for model training and testing. Collecting such data remains an important bottleneck. Here we help to address these gaps by developing and testing a methodology to simulate gully densities across Ethiopia, Eritrea and Djibouti (total area: 1.2 million km2). We propose a methodology to quickly assess the gully head density (GHD) for representative 1 km2 study sites by visually scoring the presence of gullies in Google Earth and then converting these scores to realistic estimates of GHD. Based on this approach, we compiled GHD observations for 1,700 sites. We used these data to train sets of RF regression models that simulate GHD at a 1 km2 resolution, based on topographic/geomorphic, land cover, soil and rainfall conditions. Our approach also accounts for uncertainties in GHD observations. Independent validations showed generally acceptable simulations of regional GHD patterns. We further show that: (i) model performance strongly depends on the amount of training data used, (ii) large prediction errors mainly occur in areas where also the predicted uncertainty is large and (iii) collecting additional training data for these areas results in more drastic model performance improvements. Analyses of the feature importance of predictor variables further showed that patterns of GHD across the Horn of Africa strongly depend on NDVI and annual rainfall, but also on normalized steepness index (ksn) and distance to rivers. Overall, our work opens promising perspectives to assess gully densities at continental scales. © 2020 John Wiley & Sons, Ltd.

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Section: Gully Densities Across the Horn Of Africa: A Geomorphic Intesupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Predicting gully densities at sub‐continental scales: a case study for the Horn of Africa

Vanmaercke

Chen

Haregeweyn

et al. 2020

Earth Surf Processes Landf

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“…In steep topography, hillslopes may transiently evolve to their mechanically limited threshold slope whereby any further perturbation will result in increased sediment delivery through mass-wasting processes such as rockfall or land-sliding (Bennett et al, 2016;Blöthe et al, 2015;Burbank et al, 1996;Larsen et al, 2010;Schwanghart et al, 2018). Given the erratic nature of landslides, not all threshold hillslopes will respond simultaneously to base-level lowering depending on local variations in rock strength, hydrology, land use and seismic activity (Broeckx et al, 2020;Guns and Vanacker, 2014). Therefore, catchments in transient landscapes might experience hillslope denudation with highly variable rates (Vanacker et al, 2020).…”

Section: Equilibrium Between River Incision and Hillslope Denudationmentioning

confidence: 99%

“…However, in tectonically active regimes, hillslopes tend to evolve towards a critical threshold gradient, which is controlled by mechanical rock properties (Anderson, 1994;Roering et al, 1999;Schmidt and Montgomery, 1995). Once slopes approach this critical gradient, mass wasting becomes the dominant process controlling hillslope response to changing base levels (Burbank et al, 1996). In such a configuration, hillslope gradients are no longer an indication of denudation rates (Binnie et al, 2007;Korup et al, 2007;Montgomery and Brandon, 2002), and hillslope metrics (Hurst et al, 2012) often require high-resolution topographic data that are not widely available.…”

Section: Introductionmentioning

confidence: 99%

Parameterization of river incision models requires accounting for environmental heterogeneity: insights from the tropical Andes

et al. 2020

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Abstract. Landscape evolution models can be used to assess the impact of rainfall variability on bedrock river incision over millennial timescales. However, isolating the role of rainfall variability remains difficult in natural environments, in part because environmental controls on river incision such as lithological heterogeneity are poorly constrained. In this study, we explore spatial differences in the rate of bedrock river incision in the Ecuadorian Andes using three different stream power models. A pronounced rainfall gradient due to orographic precipitation and high lithological heterogeneity enable us to explore the relative roles of these controls. First, we use an area-based stream power model to scrutinize the role of lithological heterogeneity in river incision rates. We show that lithological heterogeneity is key to predicting the spatial patterns of incision rates. Accounting for lithological heterogeneity reveals a nonlinear relationship between river steepness, a proxy for river incision, and denudation rates derived from cosmogenic radionuclide (CRNs). Second, we explore this nonlinearity using runoff-based and stochastic-threshold stream power models, combined with a hydrological dataset, to calculate spatial and temporal runoff variability. Statistical modeling suggests that the nonlinear relationship between river steepness and denudation rates can be attributed to a spatial runoff gradient and incision thresholds. Our findings have two main implications for the overall interpretation of CRN-derived denudation rates and the use of river incision models: (i) applying sophisticated stream power models to explain denudation rates at the landscape scale is only relevant when accounting for the confounding role of environmental factors such as lithology, and (ii) spatial patterns in runoff due to orographic precipitation in combination with incision thresholds explain part of the nonlinearity between river steepness and CRN-derived denudation rates. Our methodology can be used as a framework to study the coupling between river incision, lithological heterogeneity and climate at regional to continental scales.

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“…There is as yet no consensus as to the dominant contributor of the sediment transported to the oceans: the high relief mountain regions (Broeckx et al., 2020; Larsen et al., 2014; Warrick et al., 2014), or the gently sloping lowlands (Willenbring et al., 2013; Wittmann et al., 2020)? The Yangtze River is one of the largest fluvial transport systems on Earth.…”

Section: Introductionmentioning

confidence: 99%

Southeastern Tibetan Plateau serves as the dominant sand contributor to the Yangtze River: Evidence from Pb isotopic compositions of detrital K‐feldspar

et al. 2020

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There is as yet no consensus as to the dominant source of sediment transported to the oceans: the steep tectonically active highlands, or the gently sloping lowlands? In this study, new Pb isotopic analyses of detrital K‐feldspar have been combined with published data to constrain sand supply in the Yangtze River, one of the largest fluvial sediment transport systems on Earth. Tributaries draining southeastern Tibet have predominantly unradiogenic K‐feldspar sand grains. K‐feldspar in the middle Yangtze comprises c. 50% of grains of this kind, confirming that the southeastern Tibetan tributaries are the dominant sediment contributors. K‐feldspars characteristic of tributaries of the middle‐lower reaches are not strongly represented in the trunk Yangtze, indicating that they contribute little sediment. Our study demonstrates that tectonic uplift in southeastern Tibet is the primary control on sand supply. This is consistent with quartz 10Be data and with bulk‐sand petrography, indicating a major contribution of detritus from steep mountainous terrain.

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Landslide mobilization rates: A global analysis and model

Cited by 56 publications

References 132 publications

Predicting gully densities at sub‐continental scales: a case study for the Horn of Africa

Predicting gully densities at sub‐continental scales: a case study for the Horn of Africa

Parameterization of river incision models requires accounting for environmental heterogeneity: insights from the tropical Andes

Southeastern Tibetan Plateau serves as the dominant sand contributor to the Yangtze River: Evidence from Pb isotopic compositions of detrital K‐feldspar

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