Deltas are important landforms because many people live near them, and they provide a host of important services and resources.Specific patterns of spreading and contraction are produced where delta channel flow meets the ocean. Tracers on the water surface allow this pattern to be measured from space. We identify this pattern on a growing river delta in 40 years of images, allowing us to track its growth in a new way. This method has potential to improve monitoring of deltas worldwide. Hide

Barrier islands change through time and space in response to natural and human forces. This paper demonstrates that barrier island development and the beach-dune system can be influenced asymmetrically during island development by ancient and buried river valleys that cross the modern barrier island. Given the importance of the natural environment, coastal management projects should first seek to understand how the island developed in order to more effectively balance natural and human pressure. Hide

This paper presents applications of Structure-from-Motion Photogrammetry in a physical model of a braided river used to quantify morphology change and provide estimates of water depth, as well as image analysis for mapping bed surface texture. Hide

The grain-size distribution of ancient alluvial systems is commonly determined from sections of gravel deposits exposed vertically to reconstruct paleo-environments or changes in tectonic and/or climate. To test whether such grain-size distribution is equivalent to the one of the sediments that were in direct contact with the flow at the time of deposition, we dug a large trench in an active gravel-bed braided river. We show that the granulometry is uniform at the scale of the active layer. Hide

In most models of river morphodynamics, sediment mass conservation is described by the Exner equation, which may take either the flux form or the entrainment form. Here we compare the two forms of Exner equation under conditions typical of the Lower Yellow River. We find that when using a single sediment grain size, there is little difference between the two forms. But when considering sediment mixtures, the two forms will show very different patterns of grain sorting. Hide

Erosion by glaciers can limit the height to which mountains grow. The prevalence of this phenomenon is debated, and it is thought that glaciers only limit mountain height in temperate regions, where glaciers grow large during cold periods. We present evidence that glacial erosion has limited the rise of mountains in tropical Costa Rica and Taiwan, where glaciers are only intermittently present. Our work points to the remarkable efficiency of glacial erosion, even in the warmest places. Hide

Rivers can raise or lower their beds by depositing or eroding sediments. We combined equations for flow, channel geometry, and gravel transport, to learn how changes in climate and tectonics shape profiles of river-bed elevation downstream. Rivers steepen when they receive more sediment (relative to water) and become straighter with tectonic uplift. Weathering and valley widening are required to produce gradually widening rivers with concave-up profiles that are often observed in the field. Hide

This paper examines how an experimental mega-scale beach nourishment (Sand Motor) contributes to creating favorable conditions for dune development. These conditions, involving a steady supply of wind-blown sand towards space where it can accumulate, are identified using publicly available remote sensing data. It is demonstrated that the Sand Motor supports a high potential for new dunes to develop, but human disturbances may hamper this development which negatively impacts coastal safety. Hide

Glaciations may induce significant changes in the catchments of major sedimentary systems over time, also during a single glaciation. The rugged morphology of Alpine valleys may slow, block or divert glacial tongues. Such conclusion arises from the reconstruction we made of the Brenta (NE Italy) glacial system dynamics through sediment analysis techniques on its alluvial stratigraphic record and the mapping of in-valley glacial/glaciofluvial remnants. Hide

We used a numerical model to study how mountain streams adjust to series of sediment input events, e.g. landslides. We first recreated laboratory stream experiments with similar scope and then expanded their parameter space, allowing us to find when the stream becomes overloaded with sediment. This occurs when the stream cannot evacuate a sediment input in the time between pulses. Our results can help to better understand the long term adjustment of mountain streams to episodic sediment supply. Hide

In this work we combined the results of the automatic classification of continuous seismic data recorded at two arrays to identify avalanches. By using an additional post-processing step based on the localization of avalanches, we were able to identify 27 avalanches during the winter period 2016–2017. Comparing these results with visually identified avalanches, we were able to reconstruct the main avalanche periods of the winter season. Hide

Clast imbrications, which is a depositional fabric where clasts overlap each other similar to a run of toppled dominoes, are presumably the most conspicuous sedimentary structures in coarse-grained fluvial deposits. However, the conditions leading to this fabric has been contested. Here, we calculate the hydrological conditions for various stream gradients. We find that clast imbrications most likely form where channel gradients exceed a threshold and where upper flow regime conditions prevail. Hide

Identifying contemporary river migration rates is often based on aerial photos or recent topographical maps. Here, we propose to use river sediments as an archive to look further back in time using optically stimulated luminescence (OSL) dating, and develop a modelling procedure for the joint analysis of dating results and historical maps. The procedure is applied to the Overijsselse Vecht river in The Netherlands, and we show that the river migrated with 0.9–2.6 m/y between 1400–1900 AD. Hide

In the last 50 years, the Adygine glacier has been subjected to relatively fast recession comparable to other glaciers in Tien Shan. As a consequence, a 3-level cascade of glacial lakes formed, two of which were categorised as medium outburst hazard. By 2050, the glacier is expected to shrink to 56–73 % of its 2012 extent. Further development of the site will result in formation of new lakes and probably also increase of outburst hazard due to glacier runoff changes and melting of buried ice. Hide

We perform dimensional analysis on a frequently used landscape evolution model (LEM). Defining characteristic scales in a novel way, we significantly simplify the LEM and develop an efficient numerical modeling approach. Our characteristic scales are physically meaningful; they quantify competitions between landscape-forming processes and are related to salient properties of landscape topography. Dimensional analyses of other LEMs may benefit from our approach in defining characteristic scales. Hide

We present a modelling framework for the prediction of gravel-bed braided river evolution. The model is unique in that it simplifies sediment transport through the use of empirically-derived relationships between channel form and flood-scale particle transport distances, or path lengths, which ultimately allow for longer duration model runs with reduced computational demand. We use field surveys on two braided rivers to validate the model at the event, annual, and decadal timescales. Hide

In estuaries, mud sedimentation enhances salt marsh accretion. Here we explore system-scale effects of plants and mud on planform shape and size of estuaries. We coupled Delft3D for hydromorphodynamics with our vegetation model and ran controls for comparison. Effects are greatest at the fluvial-tidal transition, where for the first time in a model, a bedload convergence zone formed. Regardless of local vegetation effects, mud and vegetation cause gradual filling of estuaries over time. Hide

Mountain rivers play an important role in storing organic carbon (OC) on the landscape. We use field sampling to quantify OC concentrations in floodplain soils of two disparate mountain river basins. We find that local valley geometry and hydrology are dominant controls on OC concentration. This implies that OC concentration cannot be predicted using consistent, downstream trends. Instead, geomorphology must be accounted for to understand the spatial distribution of OC in river basins. Hide

Deep-seated gravitational spreading features are spectacular on Mars on the hillslopes of Valles Marineris, both in terms of freshness of landforms and size. This paper compares their dimensions and those in terrestrial analogue sites, in the Tatra Mountains. Gravitational spreading is thought to be now inactive in both locations. We find that height-to-width ratio, ~ 0.24, is similar, in spite of much larger strain in Valles Marineris. We explore the implications. Hide

The paper describes a model that simultaneously evolves both the soil profile and the landform, creating a coupled soilscape-landscape evolution model. The physics in the model is presented and justified from physical processes. The behaviour of the model is then explored for a variety of process formulations for a one-dimensional hillslope consisting of a flat upslope, steep midslope and flat lowlands, exploring the erosion and deposition behaviour, and soil profile evolution over time. Hide

Rainfall-induced landslides cause significant damage and fatality worldwide, but we have few datasets constraining the impact of individual storms. We present and analyze 8 landslide inventories, with > 150 to > 15,000 landslides, representing comprehensively the landslide population caused by 8 storms from Asia and the Americas. We found that the total storm rainfall is a major control on total landsliding, and that long storms seem to trigger landslides on less steep slopes than longer storms. Hide

Climate change will likely increase soil erosion in many locations worldwide. The increase of soil erosion will have a large-scale impact, such as the siltation of reservoirs. We developed a new soil erosion model to evaluate these impacts, which has the advantage over existing models that it includes most relevant processes: rainfall-runoff generation, vegetation development, and soil erosion and deposition. The model is suited to perform scenario studies on climate change and land management. Hide