Coastal marshes are valuable natural habitats with normally dense vegetation. The presence of bare patches is a symptom of habitat degradation. We found that the occurrence of bare patches and regrowth of vegetation, is related to spatial variations in soil surface elevation, and to distance and connectivity to tidal creeks. These relations are similar in three marshes at very different geographical locations. Our results may help nature managers to conserve and restore coastal marshes.

The magnitude of cooling in tropical high mountains during the last glacial period is controversially debated. Here, we report on enigmatic large sorted stone polygons and stripes from the ~ 4000 m high Sanetti Plateau in Ethiopia. Geomorphological features of that size are associated with seasonal or permanent frost and have yet only been described for few locations in the mid and high latitudes. The presence of these features implies a strong tropical cooling at high elevations in the past.

Arid ecosystem health is a complex interaction between vegetation and climate and with impacts from grazing can result in quick changes in vegetation cover. We present a wind erosion and vegetation health model with active grazers over 100-year long tests to find the limits of arid environments for different levels of vegetation, rainfall, windspeed, and grazing. The model shows the resilience of grassy landscapes to grazing and its role as an improved tool for managing arid landscapes.

The sizes and shapes of alluvial channels vary in a systematic way with the water flow they must 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 a critical hydraulic state to which channels tend to evolve. Channel width and slope can be further quantified using conservation principles.

Ongoing deformation of the Himalaya is not constrained to its' southern extremity. The 'Lesser Himalayan Duplex' lying inside the Himalayan mountain belt portray a high-relief in the western Himalaya. With morphometric analysis of the eastern Kashmir Himalaya, using high-resolution digital elevation model, satellite image analysis and field observations, we identify at least two active fault ramps emerging from the basal decollement beneath the Lesser Himalayan duplex, uplifting the Himalaya.

We examine stream-power incision and linear diffusion landscape evolution models, with and without incision thresholds. We present a steady-state relationship between curvature and the steepness index, which plots as a straight line. We view this line as a counterpart to the slope–area relationship for the case of landscapes with hillslope diffusion. We show that simple shifts and rotations of such lines express graphically the topographic response of landscapes to changes in model parameters.

Glacial landslides are difficult to detect and likely underestimated due to rapid covering or dispersal. Without improved detection rates we cannot constrain their impact on glacial dynamics, or, their potential climatically driven increases in occurrence. Here we present a new open-access tool (GERALDINE) that helps a user detect 92 % of these events over the past 37 years on a global scale. We demonstrate its ability by identifying two new, large, glacial landslides in the Hayes Range, Alaska.

High-quality digital surface models generated by automated photogrammetry techniques on aerial images captured with drones are increasingly used for topographic change detection. We demonstrate that co-aligning the images from multiple surveys strongly enhances the accuracy of topographic change detection. We find that co-alignment leads to particularly large improvements in the accuracy of poorly aligned surveys that have severe offsets when processed individually.

During the last ice age, sea level was lower, and the North Sea was land. The margin of a large ice sheet was at Dogger Bank in the North Sea. This ice sheet formed large rivers. After the ice sheet retreated down from the highpoint of Dogger Bank, the rivers had no water supply and dried out. Increased precipitation during the 15 000 years of land exposure at Dogger Bank formed a new drainage network. This study shows how glaciation and climate changes can control how drainage networks evolve.

Many contemporary models of large-scale fluvial fluvial erosion focus on the detachment-limited regime where all material entrained by the river is immediately excavated. This limitation facilitates the comparison with real river profiles and strongly reduces the numerical complexity. Here a simple formulation for the opposite case, transport-limited erosion, and a new numerical scheme that achieves almost the same numerical efficiency as detachment-limited models are presented.

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.

Looking into processes that occurs on different time scales that spans over thousand or millions of years is difficult to achieve. This is the case when we try to understand the interaction between tectonics and surface processes. Analogue modelling is an investigating technique that can overcome this limitations. Studying the erosional response of analogue landscape, varying the concentration of components of analogue materials strongly affects the evolution of experimental landscapes.

Box canyons are wide valleys that are associated with seepage of groundwater. Here we study box canyons along the Canterbury coast of New Zealand using field observations, sample analyses, drones, satellites, geophysical instruments and modelling. We show that these box canyons form when rainfall intensity is higher than 40 mm per day. The canyons form by landslides where buried channels or sand lenses are located. This information allows us to predict where box canyons may form in the future.

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 flows of sediment and water that travelled for kilometres. We describe this dramatic mass-wasting cascade and its predisposing factors, which have important implications for both the evolution of the volcanic edifices and for hazard assessment.

Sandy coasts are areas that undergo a lot of changes, which are caused by different influences, such as tides, wind or human activity. Permanent laser scanning is used to generate a 3-dimensional representations of a part of the coast continuously over an extended period. By comparing three unsupervised learning algorithms, we develop a methodology to analyse the resulting data set and derive which processes are dominating changes in the beach and dunes.

Forested, gravel bed streams possess complex channel morphologies which are difficult to objectively characterize. This manuscript describes a novel technique using a remotely piloted aircraft (RPA) to characterize these systems below the forest canopy. The results demonstrate the accuracy and coverage of RPAs for objectively characterizing and classifying these systems relative to more traditional, time consuming techniques that are generally used in these environments.

The 17 June 2017 Karrat landslide in Greenland caused a tsunami that killed four persons. We apply a multidisciplinary workflow to reconstruct a timeline of events and find that three historic landslides occurred in 2009, 2016 and 2017. We also find evidence of much older periods of landslide activity. Three newly discovered active landslides might pose a future hazard. We speculate that the trigger for the recent events is melting permafrost due to a warming climate.

Existing ways of modeling the flow of water amongst landscape depressions such as swamps and lakes take a long time to run. However, as our previous work explains, depressions can be quickly organized into a data structure – the depression hierarchy. This paper explains how the depression hierarchy can be used to quickly simulate the realistic filling of depressions including how they spill over into each other, and, if they become full enough, how they merge into one another.

Mountain streams often display a stepped morphology but the conditions under which these steps form, remain stable, and eventually collapse are still not entirely clear. We run flume experiments to study how (a) the amount of sediment input and (b) channel width variations affect steps dynamic in steep channels. Steps form preferentially in areas of flow convergence (channel narrowing) and their frequency is higher when sediment supply is larger than zero but smaller than the transport capacity.

We propose a machine learning approach for the classification and analysis of large delta systems. The approach uses remotely sensed data, channel network extraction, and the analysis of 10 metrics to identify clusters of island with similar characteristics. The 14 clusters are grouped into 6 main classes related to morphological processes acting on the system. The approach allows to identify spatial patterns in large river deltas to inform modeling and the collection of field observations.

Part of the inaccuracies when estimating bedload transport in gravel-bed rivers is because we are not considering the wide distributions of shear stress in these systems. We modified a subsurface-based bedload transport equation to include these distributions. By doing so, our approach accurately predicts bedload transport rates when the pavement layer is still present while the original one predicts zero transport. For high flows, our method had a similar performance than the original equation.

Alternate bars are large sediment deposits that tend to naturally form in rivers when the channel width is sufficiently large. Our laboratory experiments on a scaled model reveal that equilibrium properties of self-formed alternate bars highly depend on the water discharge with respect to the relevant theoretical thresholds. This work provides fundamental information for predicting the response of rivers to natural or human alterations of the flow regime.

Our new Holocene sea level curve are not only different to previously published data, but also different to global GIA models. We see that as soon as ice melting has ceased, local processes control shoreline migration and coast evolution. This indicates that more emphasis should be placed on regional coast and sea-level change modelling under a global sea-level rising future as the local government need more specific and effective advice to deal with coastal flooding.

Shape characteristics of rocks and sediments can provide crucial information about their origin and their environment, but the automation of their measurement is often time-consuming and complicated. We introduce a workflow based on a portable 3D scanner and a computer algorithm that allows for the fast and efficient recording and evaluation of the shapes of rocks. Using this method, we can examine the geometry of hundreds of particles in a few days without transporting or storing them.

One of the most interesting problems in geomorphology concerns the conditions that mobilise sediments grains in rivers. Newly developed smart pebbles allow for the measurement of those conditions directly, if a suitable framework for analysis is followed. This paper connects such a framework with the physics used to described sediment motion and presents a series of laboratory and field smart-pebble deployments. Those quantify how grain shape affects the motion of coarse sediments in rivers.