Recent  

Quantifying wood fluxes in rivers would improve our understanding of the key processes in river ecology and morphology. In this work, we introduce new software for the automatic detection of wood pieces in rivers. The results show 93.5 % and 86.5 % accuracy for piece number and volume, respectively.

Seismic techniques applied in rock slope failure research do not provide rapid notifications, as for earthquakes, due to the lack of connections between seismic signals and events. We studied 10 known events in Taiwan and developed a GeoLoc scheme to locate rock slope failures, estimate the event volume, and understand their physical process using available videos. With real-time seismic data transmission, a rapid report can be created for the public within several minutes of the event.

Ongoing deformation of the Himalaya is not constrained to its southern extremity. With morphometric analysis using a high-resolution digital elevation model, satellite image analysis, luminescence chronology of fluvial terraces and field observations, we identify a zone of rapid rock uplift in the interior of the Kashmir Himalaya. Our results suggest active tectonic and structural control on the growth of topography in the Himalayan interiors over multi-millennial timescales.

We investigated how shallow landslide occurrence is impacted by deforestation and rifting in the North Tanganyika–Kivu rift region (Africa). We developed a new approach to calculate landslide erosion rates based on an inventory compiled in biased © Google Earth imagery. We find that deforestation increases landslide erosion by a factor of 2–8 and for a period of roughly 15 years. However, the exact impact of deforestation depends on the geomorphic context of the landscape (rejuvenated/relict).

Despite the inherent difficulties in quantifying its value, sediment transport is essential to understanding fluvial systems. This study tries to improve the measurement by comparing several methods. Acoustic methods are compared to direct measurements with samplers. The hydrophone is well adapted to quantify sediment transport in mountain streams, but this study shows the potential and the efficiency of this device in large lowland rivers.

We measured the shear strength of marsh soils along an estuarine salinity gradient to determine salinity's influence on marsh erodibility. Our work is one of the first studies to directly examine the relationship between salinity and marsh erodibility. We find that an increase in salinity correlates with higher soil shear strength values, indicating that salt marshes may be more resistant to erosion. We also show that both belowground biomass and soil properties drive shear strength differences.

The Puebla–Morelos earthquake (19 September 2017) was the most damaging event in central Mexico since 1985. The seismic shaking produced hundreds of shallow landslides on the slopes of Popocatépetl Volcano. The larger landslides transformed into large debris flows that travelled for kilometers. We describe this exceptional mass wasting cascade and its predisposing factors, which have important implications for both the evolution of the volcanic edifice and hazard assessment.

The sizes and shapes of alluvial channels vary in a systematic way with the water flow they convey during large floods. It is demonstrated that the depth of alluvial channels is controlled by the resistance of channel bank material to slumping, which in turn is controlled by clay content. Deeper channels have faster water flow in a manner controlled by the critical hydraulic state to which channels tend to evolve. Channel width and slope can be further quantified using conservation principles.

Despite a history of landslide damming and flash floods in the NW Himalaya, only a few studies have been performed. This study predicts some potential landslide damming sites in the Satluj valley, NW Himalaya, using field observations, laboratory analyses, geomorphic proxies, and numerical simulations. Five landslides, comprising a total landslide volume of 26.3 ± 6.7 M m³, are found to have the potential to block the river in the case of slope failure.

Mountain rivers are characterized by fluctuations of water flow, including both flood and inter-flood low flow. Recently, increasing attention has been paid to how inter-flood low flow affects the sediment transport in subsequent floods. Here we present a series of flume experiments. Results show that the existence of inter-flood low flow can reduce the sediment transport at the beginning of the subsequent flood. However, such an effect is gradually erased with the increase of flow intensity.

This paper explores how the geometry of rill networks contributes to observed nonlinear relationships between soil loss and hillslope length. This work develops probability functions of geometrical quantities of the networks and then extends the theory to hydraulic variables by relying on well-known relationships. Theory is complemented by numerical modeling on numerical and natural surfaces. Results suggest that the particular arrangement of rill networks contributes to nonlinear relationships.

We use long-range smart sensors connected to a network based on the Internet of Things to explore the possibility of detecting hazardous boulder movements in real time. Prior to the 2019 monsoon season we inserted the devices in 23 boulders spread over debris flow channels and a landslide in northeastern Nepal. The data obtained in this pilot study show the potential of this technology to be used in remote hazard-prone areas in future early warning systems.

Large avalanches composed of ice and rock are a serious hazard to mountain communities and backcountry travellers. These processes shake the Earth and disturb the atmosphere, generating seismic waves and sound waves which can travel for hundreds of kilometers. In this study, we use the seismic waves and sound waves produced by two massive avalanches on a volcano in Alaska to reconstruct how the avalanches failed. Our method may assist with rapid emergency response to these global hazards.

We present a set of observations from laboratory experiments on meltwater meandering rivulets on ice and compare them (qualitatively and quantitatively) to patterns commonly found in meandering channels flowing over different materials. Our channels display great similarities with real rivers in spite of being much smaller. Higher temperature differences between water and ice create deeper and less sinuous channels with bends that preferentially point downstream and are not as rounded.

Abrasion of sedimentary particles is widely associated with mutual collisions. Utilizing results of individual, geometric abrasion theory and techniques adopted in statistical physics, a new model for predicting the collective mass evolution of large numbers of particles is introduced. Our model uncovers a startling fundamental feature of collective particle dynamics: collisional abrasion may either focus size distributions or it may act in the opposite direction by dispersing the distribution.

Wave-transported boulders are important records for storm and tsunami impact over geological timescales. Their use for hazard assessment requires chronological information. We investigated the potential of a new dating technique, luminescence rock surface exposure dating, for estimating transport ages of wave-emplaced boulders. Our results indicate that the new approach may provide chronological information on decadal to millennial timescales for boulders not datable by any other method so far.

The world's sandy coastlines are increasingly altered by humans and sea-level rise, yet quantitative relationships between coastal landscapes and sediment availability remain poorly described. Using a novel modeling framework, we explore the evolution of coastal barrier islands under varying rates of sea-level rise and sediment availability. Our model results suggest that as sea levels increase, minor changes in sediment availability could result in rapid changes to barrier coasts.