Recent  

Arctic rivers erode into permafrost and mobilize organic carbon, which can react to form greenhouse gasses or be re-buried in floodplain deposits. We collected samples on a permafrost floodplain in Alaska to determine if more carbon is eroded or deposited by river meandering. The floodplain contained a mixture of young carbon fixed by the biosphere and old, re-deposited carbon. Thus, sediment storage may allow Arctic river floodplains to retain aged organic carbon even when permafrost thaws.

Landscape erosion is generally considered to take place vertically downward. Here, by writing gradient-driven erosion in Hamiltonian form, we show this is not true. Instead, we find it takes place in two directions simultaneously: (i) normal to the surface and (ii) along rays pointing upstream and either up or down depending on how erosion rate scales with slope. The rays follow the shortest time paths that determine how long it takes for a landscape to respond to changes in external conditions.

Floodplain formation in estuaries limit the ebb and flood flow, reducing channel migration and shortening the tidally influenced reach. Vegetation establishment on bars reduces local flow velocity and concentrates flow into channels, while mudflats fill accommodation space and reduce channel migration. These results are based on experimental estuaries in the Metronome facility supported by numerical flow modelling.

We compiled a large image dataset containing more than 125 000 sediments and developed a model (GrainID) based on convolutional neural networks to measure individual grain size from images. The model was calibrated on flume and natural stream images covering a wide range of fluvial environments. The model showed high performance compared with other methods. Our model showed great potential for grain size measurements from a small patch of sediment in a flume to a watershed-scale drone survey.

Some types of big earthquakes create small cliffs or fault scarps ∼1–3 m in height, where sediments can pile up and create deposits we call colluvial wedges. Geologists will look at colluvial wedges and use them to understand how often big earthquakes occur. Here we made a computer simulation to find out if the way we think colluvial wedges form works with physics. We found that it does in theory, but there are conditions in which it may be more complicated than we expected.

By comparing two models for the transport of sediment, we find that they share a similar steady-state solution that adequately predicts the shape of most depositional systems made of a fan and an alluvial plain. The length of the fan is controlled by the size of the mountain drainage area feeding the sedimentary system and its slope by the incoming sedimentary flux. We show that the models differ in their transient behavior to external forcing and are characterized by different response times.

Bedload flux quantification remains challenging in river dynamics due to variable transport modes. We used a passive monitoring device to record the acoustic signals generated by the impacts of bedload particles with different transport modes, and established the relationship between the triggered signals and bedload characteristics. The findings of this study could improve our understanding of the monitoring system and bedload transport process, and contribute to bedload size classification.

The condition of peatland largely determines its capacity to store carbon, but peatland condition is not accurately known. Combining the knowledge of management, vegetation, and detecting differences in seasonal surface movement from satellite radar data, we map peat condition. In a blanket bog landscape we discovered the presence of wetter and dryer conditions, which could help guide restoration decisions, and we conclude that this approach could  be transferred peat management worldwide.

Channel behaviour is a qualitative aspect of river research that needs development to produce a framework of analysis between and within types of channels. We seek to produce a quantitative metric that can capture how a channel changes using a pair of experiments and collecting easy to obtain data. We demonstrate that this new technique is capable of discerning between river types and may provide a new tool with which we may describe channel behaviour.

Rivers are known to record changes in tectonic or climatic variation through long adjustment of their longitudinal profile slope. Here we describe such adjustments in experimental landscapes and show that they may result from the sole effect of intrinsic geomorphic processes. We propose a new model of river evolution that links long profile adjustment to cycles of river widening and narrowing. This result emphasizes the need to better understand control of lateral erosion on river width.

Beida River has an over-steepened reach presently located 10 km upstream of the North Qilian mountain front. It was formed because river incising into the bedrocks inside the mountain cannot keep up with river incising into the soft sediment in the basin. We suggest this over-steepened reach represents a fast incision period 3–4 kyr ago, deepening the canyon for ~35 m within ~700 years. The formation of this reach corresponds to a humid period related to strong Southeast Asian Monsoon influence.

Obtaining accurate information on the volume of geomorphic features typically requires high-resolution topographic data, which are often not available. Here, we show that the globally available 12 m TanDEM-X DEM can be used to accurately estimate gully volumes and establish an area–volume relationship after applying a correction. This allowed us to get a first estimate of the amount of sediment that has been mobilized by large gullies (lavaka) in central Madagascar over the past 70 years.

We present the first physics-based general landslide velocity model incorporating internal deformation and external forces. Voellmy–inviscid Burgers' equations are specifications of the novel advective–dissipative system. Unified analytical solutions constitute a new foundation of landslide velocity, providing key information to instantly estimate impact forces and describe breaking waves and folding, revealing that landslide dynamics are architectured by advection and reigned by forcing.

Recently, along the east coast of South Korea, seasonal beach erosion has been induced by structures which severely block the supply of sand from the upstream side. This study proposes a coastal solution that can predict the maximum indentation point in downdrift erosion formed downstream of groins by applying a parabolic bay shape equation (PBSE).