Recent  

Preservation bias often hampers the extraction of sea level changes from the stratigraphic record. In this contribution, we use a forward stratigraphic model to build three synthetic subtropical fringing reefs for a site in southwestern Madagascar (Indian Ocean). Each of the three synthetic reefs represents a different ice sheet melt scenario for the Pleistocene. We then evaluate each resultant reef sequence against the observed stratigraphic record.

Quantitative knowledge of water availability on high mountain rock slopes is very limited. We use a numerical model and field measurements to estimate the water balance at a steep rock wall site. We show that snowmelt is the main source of water at elevations >3600 m and that snowpack hydrology and sublimation are key factors. The new information presented here can be used to improve the understanding of thermal, hydrogeological, and mechanical processes on steep mountain rock slopes.

We combined data from satellite images with data measured from a kayak in order to understand the propagation of fine sediment in the Vjosa River. We were able to find some storm-activated and some permanent sources of sediment. We also estimated how much fine sediment is carried into the Adriatic Sea by the Vjosa River: approximately 2.5 Mt per year, which matches previous findings. With our work, we hope to show the potential of open-access satellite images.

We compare models of erosion against a global compilation of long-term erosion rates in order to find and interpret best-fit parameters using an iterative search. We find global signals among exponents which control the relationship between erosion rate and slope, as well as other parameters which are common in long-term erosion modelling. Finally, we analyse the global variability in parameters and find a correlation between precipitation and coefficients for optimised models.

We examine differences in glacier extent in the Olympic Mountains, USA, where modern precipitation in east-facing valleys is only 50 % of that in west-facing valleys. During the Last Glacial Period, there were very small glaciers in the east and very large glaciers in the west. We use climate data and glacier models to show that the modern spatial pattern of precipitation is likely to have been similar during the past glaciation and may be sufficient to explain the asymmetry of glacier extent.

Despite the importance of bedforms (e.g., ripples, dunes) to sediment transport, the details of sediment transport on a sub-bedform scale are poorly understood. This paper investigates sediment transport in the downstream and cross-stream directions over bedforms with straight crests. We find that the patterns of bedload transport are highly variable on the sub-bedform scale, which is important for our understanding of the evolution of bedforms with complex crest geometries.

Many steep glaciated rock walls collapsed when the Ice Age ended. How ice supports a steep rock wall until the ice decays is poorly understood. A collapsed rock wall was surveyed in the field and numerically modelled. Cosmogenic exposure dates show it collapsed and became ice-free ca. 18 ka ago. The model showed that the rock wall failed very slowly because ice was buttressing the slope. Dating other collapsed rock walls can improve understanding of how and when the last Ice Age ended.

Sand dune migration velocity is inversely proportional to dune size. Consequently, smaller, faster dunes can collide with larger, slower downstream dunes. Such collisions can result in either coalescence or ejection, whereby the dunes exchange mass but remain separate. Our numerical simulations show that the outcome depends probabilistically on the dune size ratio, which we describe through an empirical function. Our numerical predictions compare favourably against experimental observations.

Swiss researchers carried out repeated rockfall experiments with rocks up to human sizes in a steep mountain forest. This study focuses mainly on the effects of the rock shape and lying deadwood. In forested areas, cubic-shaped rocks showed a longer mean runout distance than platy-shaped rocks. Deadwood especially reduced the runouts of these cubic rocks. The findings enrich standard practices in modern rockfall hazard zoning assessments and strongly urge the incorporation of rock shape effects.

The transition from hillslopes to channelized flow is typically attributed to a threshold catchment size in landform evolution models. Here we propose an alternative concept directly based on topography. Using this concept, channels and hillslopes self-organize, whereby the catchment size of the channel heads varies over some range. Our numerical results suggest that this concept works better than the established idea of a strict threshold catchment size.

Earthquakes can cause damaging coastal cliff retreat, but we have a limited understanding of how these infrequent events influence multidecadal retreat. This makes hazard planning a challenge. In this study, we use historic aerial images to measure coastal cliff-top retreat at a site in New Zealand. We find that earthquakes account for close to half of multidecadal retreat at this site, and our results have helped us to develop tools for estimating the influence of earthquakes at other sites.

Tectonics and surface processes work together in shaping orogens through their evolution. Laboratory models are used to overcome some limitations of direct observations since they allow for continuous and detailed analysis of analog orogens. We use a rectangular box filled with an analog material made of granular materials to study how erosional laws apply and how erosion affects the analog landscape as a function of the applied boundary conditions (regional slope and rainfall rate).

Our detailed investigation of Martian gullies formed in different substrates in 29 craters distributed between 30°–75° S latitude suggests that they can be differentiated from one another in terms of (1) morphology and length of alcoves and (2) mean gradient of the gully fans. The comparison between the Melton ratio, alcove length, and fan gradient of Martian and terrestrial gullies suggests that Martian gullies were likely formed by terrestrial debris-flow-like processes in the past.

Landscape evolution models allow us to simulate the way the Earth's surface is shaped and help us to understand relevant processes, in turn helping us to manage landscapes better. The models typically represent the land surface using a grid of square cells of equal size, averaging heights in those squares. This study shows that the size chosen by the modeller for these grid cells is important, with larger sizes making sediment output events larger but less frequent.

It is of great importance to engineers and geomorphologists to predict the rate of bed load in rivers. In this contribution, we used a large dataset of measured data and developed an artificial neural network (ANN), a machine learning algorithm, for bed load prediction. The ANN model predicted the bed load flux close to measured values and better than the ones obtained from four standard bed load models with varying degrees of complexity.

This paper presents a two-dimensional subglacial sediment transport model that evolves a sediment layer in response to subglacial sediment transport conditions. The model captures sediment transport in supply- and transport-limited regimes across a glacier's bed and considers both the creation and transport of sediment. Model outputs show how the spatial distribution of sediment and water below a glacier can impact the glacier's discharge of sediment and erosion of bedrock.

The aim of this review is to summarise the current knowledge about mud-volcano-like structures on Mars, address critical aspects of the process of sedimentary volcanism, identify key open questions, and point to areas where further research is needed to understand this phenomenon and its importance in the Red Planet's geological evolution.

We use experiments and a model to study the effects of confinement width and the inflow-to-sediment discharge ratio on the evolution of submarine braided channels. We find that confinement width controls most of the morphological changes. These trends are consistent for submarine braided channels both with and without confinement width effects and similar to fluvial braided rivers. Furthermore, we built a model that can simulate the flow bifurcation and confluence of submarine braided channels.

We present a method to extract surface change information from 4D time series of topographic point clouds recorded with a terrestrial laser scanner. The method uses sensor information to spatially and temporally smooth the data, reducing uncertainties. The Kalman filter used for the temporal smoothing also allows us to interpolate over data gaps or extrapolate into the future. Clustering areas where change histories are similar allows us to identify processes that may have the same causes.

Underwater dunes are found in various environments with strong hydrodynamics and sandy sediment. Using a numerical model, we investigated how the dune shape influences flow velocity and turbulence. We propose a classification with three types of dunes, depending on their mean lee side angles (low-angle dunes, intermediate-angle dunes and high-angle dunes). We discuss the implications of this classification on the interaction between dune morphology, flow and sediment transport.

Extracting paleoenvironmets from sedimentologic and geomorphic records is a main goal in Earth sciences. We study a chain of processes connecting causative Mediterranean cyclones, coeval floods, storm waves generated by mesoscale funneled wind, and coastal gravel transport. This causes northward dispersion of gravel along the modern Dead Sea coast, which has also persisted since the late Pleistocene, resulting in beach berms and fan deltas always being deposited north of channel mouths.