Here we explore what controls river resilience to valley blocking by slow landslides. We link differences in landslide blocking at two locations to an analysis of the mobility of landslide-derived boulders. Our results suggest that the formation of valley blockages by slow landslides is very sensitive to the mobility of the coarsest fraction of sediment. Like steep alluvial channels, landslide impacted channels can be jammed by immobile boulders that locally impede coarse sediment transport.

Sand and mud may take many different pathways within a river as they travel from inland to the coast. During the trip, grains may be exposed to daylight, resetting a signal trapped within certain minerals. The signal can be measured in a laboratory to estimate time since last light exposure. Here, we measure the trapped signal of sand and mud grains from the Mississippi River and its banks. We use this information to infer sediment pathways. Such knowledge is useful for delta management.

Given the task of a rockfall hazard assessment, knowledge about the precise flight path of assumed boulders is vital for its accuracy. We present the full reconstruction of artificially induced rockfall events. The extracted information such as exact velocities, jump heights and lengths provide detailed insights of how rotating rocks interact with the ground. The information serves as future calibrations of rockfall modelling tools with the goal of even more realistic modelling predictions.

Slow-moving landslides are a major hazard but their movement mechanisms during earthquakes and rainstorms are not fully understood. We collected samples from a slow-moving landslide complex in New Zealand and subjected them to a range of pore water pressure and dynamic stress scenarios in a Dynamic Back Pressured Shear Box. Our results show how the complex movement patterns, observed in many large, slow-moving landslides, may be mobilized by strong earthquakes and significant rain events.

A single storm event can change the shape of a sandy beach dramatically – but beaches also exhibit a remarkable ability to recover. So how important are storm-driven changes to a beach in the long term? This question affects predictions of future shoreline change. Here we explore signal shredding – when sediment transport erases any signature of outside driving forces. Our results suggest that major storm impacts tell us little about long-term shoreline change, and vice versa.

The shape of landscapes is influenced by climate changes, faulting or the nature of the rocks under its surface. One of the most sensitive part of the landscape to these changes is the river system that eventually adapt to such changes by adapting its slope, the most extreme example being a waterfall. We here present an algorithm that extract changes in river slope over large areas from satellite data in the aim of investigate climatic, tectonic or geologic changes in the landscape.

We mapped landslides (> 100 m²) in the Nepal Himalayas due to 8 monsoons and large landslides (> 0.1 km²) since 1970. Adding inventories of Holocene, giant landslides (> 1 km³), and of landslides from the 2015 Gorkha earthquake, we constrain the size-frequency distribution of landslides induced by monsoons and earthquakes. They both contribute ~ 50 % to a long-term (> 10 kyr) total erosion of ~ 2 mm/yr, matching long-term exhumation rate. Large landslides, rarer than ¹⁰Be sampling time, drive erosion.

In Bangladesh, we measure how water and sediment move through tidal channels in an area heavily impacted by both sea level rise and the strategies that humans use to adapt. We found that the amount of water moving through the system is largely controlled by the strength of the tides, while the mass of sediment being transported is strongly connected to the season, and to a lesser extent the tides. These results are important for developing strategies to protect both human and natural landscapes.

Using data obtained from multiple UAV flights over a debris-covered glacier in the Himalaya between 2013 and 2018 we show that the adjacent moraines erode at rates of up to 30 cm per year, contributing to this debris cover. With retreating ice and resulting instability of moraines this causes the glacier to cover itself in ever thicker layers of rocks, resulting in a possible future decrease of local melt.

Our study reveals that worldwide mean erosion rates on the million year scale are very similar to present-day erosion rates in contrast to the majority of the previously published results. Concerning the dependence of erosion on climate we found that the long-term erosion efficacy of the tropical zone has been about five times higher than that of the cold zones, while the erosional efficacy of the present-day arid zone has been as high as that of the temperate zone.

In many coastal, riverine, deltaic, marine, and subglacial systems, plentiful fine bed sediment is produced and moved to change the surface features and surrounding environments along its pathway. Our numerical research shows that, in these systems, weakened bed level changes can reduce bed friction and produce higher sediment yield, whose effects can be amplified under greater water depth. This finding can help predict sediment movement and bed level changes of water channels.

Mountain-building processes are often investigated by assuming a steady-state, meaning the balance between opposing forces, like e.g. mass influx and mass outflux. In this study we show that the assumption of steady-state for the Olympic Mountains is depending on the timescale and the spatial geometry, and particularly affected by the Quaternary glaciation. This indicates that mountain ranges can be out of steady-state during parts of their evolution.

We present in this mostly theoretical contribution a systematic treatment of tracer particle mixing in soils. We elaborate the consequences of rarefied (non-continuum) conditions of transport and mixing, and we augment this with numerical analyses that reveal important information not readily apparent in the analytical formulations, including an illustration of the variability in ¹⁰Be concentrations and OSL ages of individual particles in soils, with implications for interpreting field data.

We evaluated the performance of the low-cost seismic sensors Raspberry Shake (RS) to identify and monitor rock fall activity in alpine environments. The sensors have been tested for 1-year period in high alpine environment, recording numerous rock failure events as well as local and distant earthquakes. This study demonstrates that the RS instruments provide a good option to build low seismic monitoring networks to monitor different kind of geophysical phenomena.

High resolution digital elevation models (DEM) can be now frequently acquired using airborne Laser scanner. This allows to analyse in great details the geometry of landslides. Several large landslides were triggered by the Typhoon Talas in Japan in 2011. The comparison of pre- and post-DEM allowed to test a method defining the landslide failure surfaces before the catastrophic movements. It provides new results about the curvature of the failure surface and the volume expansion of the deposit.