Tracking the position of tracer particles entrained in a river is a popular method to investigate sediment transport. Using numerical simulations, we study the propagation of these tracers and find a transition between two regimes: an early regime in which the tracers are progressively set into motion and a late regime in which the tracers spread linearly. We derive analytical expressions for the behavior of the tracers in each regime. These expressions might help to interpret field data. Hide

The Ebro and Duero basins share a very common geological history. However, since the late Miocene, the Ebro basin has recorded important unfilling and excavation, whereas the Duero basin has only recorded limited incision and is considered to be still almost endorheic. Such a morphologic contrast led to important drainage reorganization and divide migration toward the Duero basin. Drainage area loss results in the lowering of the incision capacity of the Duero River, increasing this contrast. Hide

The Oroville Dam flood control spillway suffered catastrophic erosion damage in February 2017. We find that seismic waves recorded by a seismometer 2 km away contain information about the flow turbulence and damage location in the spillway. We show that enhanced turbulence due to spillway damage excites louder seismic waves at a given flow rate, which can be used to detect the onset and track the migration of erosion damage. The methods we use could be used to monitor other structures or rivers. Hide

Measurements of cosmogenic nuclides ¹⁰Be and ²⁶Al in sediment along central Australian streams show that lithologically controlled magnitudes of source-area erosion rates (0.2–11 m Myr^-1) are preserved downstream despite sediment mixing. Conversely, downstream-increasing sediment burial signals (> 400 kyr) indicate sediment incorporation from adjacent, long-exposed storages, which, combined with low sediment supply and discontinuous flux, likely favours source-area ¹⁰Be–²⁶Al signal masking. Hide

We used a numerical model to assess the effect of grain size and rock composition on chemical weathering and grain detachment. Our simulations showed that grain detachment represents more than a third of the overall weathering rate. We also found that as grain size increases, the weathering rate initially decreases; however, beyond a critical size, the rate became approximately constant. Our results could help predict the sometimes complex relationship between rock type and weathering rate. Hide

The importance of increasing the degree of automation in the context of monitoring natural hazards or geological phenomena is apparent. A vital step in the processing chain of monitoring deformations is the transformation of captured epochs into a common reference systems. This led to the motivation to develop an algorithm that realistically carries out this task. The algorithm was tested on three different geomorphic events while the results were quite satisfactory. Hide

We use a climate model and statistics to provide an overview of regional climates from different times in the late Cenozoic. We focus on tectonically active mountain ranges in particular. Our results highlight significant changes in climates throughout the late Cenozoic, which should be taken into consideration when interpreting erosion rates. We also document the differences between model- and proxy-based estimates for late Cenozoic climate change in South America and Tibet. Hide

We present a new method to interpret a type of data that geologists obtained by dating minerals in river sand samples. We show that such data contain information about the spatial distribution of the erosion rate (wear of surface rocks by natural processes such as river incision, land sliding or weathering) in the regions neighboring the river. This is important to understand the nature and efficiency of the processes responsible for surface erosion in mountain belts. Hide

Salt marshes are valuable environments that provide multiple services to coastal communities. However, their fast-paced evolution poses a challenge to monitoring campaigns due to time-consuming processing. The Topographic Identification of Platforms (TIP) method uses high-resolution topographic data to automatically detect the limits of salt marsh platforms within a landscape. The TIP method provides sufficient accuracy to monitor salt marsh change over time, facilitating coastal management. Hide

The role of mountain uplift and associated silicate weathering in the global climate over geological times is controversial. Previous soil column models suggest that weathering falls at a high denudation rate. We present the results of a 3-D model that couples erosion and weathering, a CO₂ consumer during mountain uplift. Our model suggests that the weathering of temporarily stocked colluvium may contribute significantly to the mountain weathering outflux at high denudation rates. Hide

Sticky sediments are an important component of many rivers and coasts. Stickiness depends on many factors including the presence of micro-organisms, also known as biofilms. We performed a laboratory study to better understand the role of biofilms in controlling sediment transport and dynamics. We find that sand with biofilms requires significantly higher flow velocities to be mobilised compared to uncolonised sand. This will help improve predictions of sediment in response to currents and waves. Hide

To study the effectiveness of river delta restoration, we used field observations and elevation data to quantify the magnitude and spatial patterns of aggradation and erosion in a restored wetland in the Rhine-Meuse delta. Erosion and aggradation rates decrease over time, but aggradation compensates for sea-level rise and soil subsidence. Channels in the centre had aggraded, whereas the inlet and outlet eroded. Furthermore, sediment is in general uniformly distributed over the intertidal area. Hide

Sediments produced by glaciers are transported by rivers and wind toward the ocean. During their journey, these sediments are weathered, and we know that this has an impact on climate. One key factor is time, but the duration of this journey is largely unknown. We were able to measure the average time that sediment spends only in the glacial area. This time is 100–200 kyr, which is long and allows a lot of processes to act on sediments during their journey. Hide

This paper analyses the timing of topographical changes of a gravel bed ephemeral river channel during consecutive and moderate- and low-magnitude floods by applying a morphodynamic model calibrated with pre- and post-event surveys using RTK-GPS and mobile laser scanning. The channel acted as a braided river during lower flows but as a meandering river during higher flows. The channel changes can be greater during the long-lasting receding phase than during the rising phase of the floods. Hide

For many applications in Earth sciences it is important to know where river and ocean sediments have originated. In this study we used geochemical and mineralogical tracers to characterise sediments from Svalbard. We find that the sediments are formed from two sources: old rocks in Greenland and younger rocks in Siberia. Glaciation influences how much of each end-member is present in the river sediments today, implying that the sediment composition can change through time as the climate changes. Hide

We present a method to analyse surface change using 3-D data collected at hourly intervals. This is applied to 9000 surveys of a failing rock slope, acquired over 10 months. A higher proportion and frequency of small rockfall is observed than in less-frequent (e.g. monthly) monitoring. However, quantifying longer-term erosion rates may be more suited to less-frequent data collection, which contains lower accumulative errors due to the number of surveys and the lower proportion of small events. Hide