Recent  

This paper presents a new approach to modeling glacial erosion on large scales. The formalism is similar to large-scale models of fluvial erosion, so glacial and fluvial processes can be easily combined. The model is simpler and numerically less demanding than established models based on a more detailed description of the ice flux. The numerical implementation achieves almost the efficiency of purely fluvial models, so that simulations over millions of years can be performed on standard PCs.

We develop a hybrid model to estimate the spatial distribution of the thickness of the soil layer, which also provides estimations of soil transport and soil production rates. We apply this model to two examples of hillslopes in the East River Watershed in Colorado and validate the model. The results show that the north-facing (NF) hillslope has a deeper soil layer than the south-facing (SF) hillslope, and the hybrid model provides better accuracy than a Machine Learning model.

Increased salt intrusion jeopardizes freshwater supply to the Mekong Delta, and the current trends are often inaccurately associated to sea level rise. Using observations and models, we show that salinity is highly sensitive to ocean surge, tides, water demand and upstream discharge. We showcase that anthropogenic riverbed incision has significantly amplified salt intrusion, exemplifying the gravity of preserving sediment budget and riverbed levels to protect the deltas against salt intrusion.

Major mountain earthquakes often trigger numerous co-seismic landslides. Vegetation dynamics on landslides can be used to indicate post-seismic landslide activity. We used thousands of remote sensing images and possible influencing factors to uncover the spatial pattern and drivers of vegetation recovery on landslides after the great 2008 Sichuan earthquake. Detailed pattern for the entire region is revealed and three paramount influencing factors were determined.

Elevated low-relief regions and major river knickpoints have for long been noticed and questioned in the emblematic Bhutan Himalayas. We document the morphology of this region using morphometric analyses and field observations, at a variety of spatial scales. Our findings reveal a highly unstable river network, with numerous non-coeval river captures, most probably related to a dynamic response to local tectonic uplift in the mountain hinterland.

Sandbars are an essential form of riverbed morphology which could be affected by landslide dams. However, few studies have focused on the formation processes and development characteristics of sandbars triggered by outburst flood. In such a way, eight group dam failure experiments with 4 to 7 times of dam length movable bed is carried out to study the temporal and spatial distributions of 25 sandbars along the riverbeds, the sandbars geometric characteristics, and the influence of outburst flow.

Seismic techniques applied in rock slope failures do not provide rapid notifications, such as earthquakes, due to the lack of connections between seismic signals and events. We studied ten known events in Taiwan and developed a GeoLoc scheme to locate rock slope failures, estimate the event volume, and understand their physical process by available videos. With real-time seismic data transmission, a rapid report can be created within several minutes after the event to the public.

Large creeping landslides are persistent features in mountainous landscapes. In order to quantify the long-term evolution of landslides and their interaction with river channels, we use a new metric for landslide-induced channel offset, which allows us to identify locations associated with increased landslide activity and estimate landslide displacement rates over a period of 1 Myr.

The world's sandy coastlines are increasingly altered by humans and sea-level rise, yet quantitative relationships between coastal landscapes and sediment availability remain poorly described. Using a novel modeling framework, we explore the evolution of coastal barrier islands under varying rates of sea-level rise and sediment availability. Our model results suggest that as sea levels increase, minor changes in sediment availability could result in rapid changes to barrier coasts.

Quantifying wood fluxes in rivers would improve our understanding of the key processes in river ecology and morphology. In this work, we introduce new software for the automatic detection of wood pieces in rivers. The results show 93.5 % and 86.5 % accuracy for piece number and volume respectively.

This paper proposes a method to reconstruct the hydraulic conditions of turbidity currents from turbidites. We investigated validity and problems of this method in application to acutual field datasets using artificial data. Once this method is established, it is expected that the method will elucidate the generation process of turbidity currents and will help to predict the geometry of resultant turbidites in deep sea environemnts.

Studies of the impact of storms on dunes typically focus on the importance of dune elevation, here we analyze the protective services offered by the dune height and width, the morphology of the beach fronting the dune, and artificial dune construction via the use of sand fences. We find that dune volume loss most strongly correlates to beach width rather than dune shape, although when beach width is controlled for low/wide dunes offer greater protection than tall/narrow dunes.

The rise of a mountain affects the circulation of water, both in the atmosphere and over the land surface, thereby affecting the erosion of the land surface. We document how the rise of a mountain in Central Guatemala has affected the erosion of an older range nearby. The new range intercepts precipitation formerly delivered to the older range. Rivers response to the uplift of the new range has decreased incision across the older one. Both have reduced hillslope erosion over the old range.

We present a set of observations from laboratory experiments on meltwater meandering rivulets on ice and compare them (qualitatively and quantitatively) to patterns commonly found in meandering channels flowing over different materials. Our channels display great similarities with real rivers in spite of being much smaller. Higher temperature differences between water and ice create deeper and less sinuous channels with bends that preferentially point downstream and are not as rounded.

We conducted experiments to investigate the mechanics of sediment attrition due to collisions with the channel bed during downstream transport. During this process, the grains become rounder and smaller, changing the overall distribution of sediment in the river. In this work we examine how material properties play a role in the breakdown of sediment due to energetic collisions as well as the fine particles that are produced when chipped off of larger grains.

Abrasion of sedimentary particles, is widely associated with mutual collisions. Utilizing results of individual, geometric abrasion theory, and techniques adopted in statistical physics, a new model for predicting the collective mass evolution of large number of particles is introduced. Our model uncovers a startling fundamental feature of collective particle dynamics: collisional abrasion may either focus size distributions or it may act in the opposite direction by dispersing the distribution.

We investigate laboratory scale, sliding analogue rock masses (avalanches) undergoing fragmentation. We find that travel distance (runout) is controlled by the degree of fragmentation. Fragmentation increases mobility of the rock mass but on the other hand consumes energy and therefore reduces the runout from its theoretically given maximum dictated by the friction at its base. We derive a mathematical formulation describing this interplay and which may useful for hazard assessment.

We investigated how shallow landslide occurrence is impacted by deforestation and rifting in the North Tanganyika-Kivu Rift region (Africa). We developed a new approach to calculate landslide erosion rates based on an inventory compiled in biased Google Earth imagery. We find that deforestation increases landslide erosion with a factor 2 to 8 and for a period of roughly 15 years. However, the exact impact of deforestation depends on the geomorphic context of the landscape (rejuvenated/relict).