Earth Surface Processes and Landforms最新文献

Equilibrium shoreline change models with calibrated, time-invariant free parameters have demonstrated good skill in hindcasting shoreline evolution at sites dominated by cross-shore sediment transport. However, their performance can be biased by the specific conditions present during the calibration period. In this study, a dual parameter-state ensemble Kalman filter (EnKF) was applied to track non-stationarity in model free parameters at three sites along the west coast of Europe. Introducing time-varying parameters did not substantially improve performance relative to an already well-calibrated stationary model. Model skill improvement occurred mainly during the EnKF correction step, highlighting the potential of real-time data assimilation for maintaining model stability. Although variations in model parameters may compensate for unresolved processes and should be interpreted cautiously, incorporating climate-driven, time-varying parameters could improve extreme-event predictions at seasonally dominated sites and enhance overall model performance in regions influenced by complex, multimodal wave climates.

Rockfalls are an efficient agent of landscape denudation and a crucial but poorly quantified component of the glacier debris supply cascade. Climate change is driving increased rockfall generation as rising air temperatures cause glacier thinning and thawing of permafrost. These processes alter rock slope stress profiles and thermal regimes, leading to greater sediment fluxes in cryospheric systems as landscapes adjust to ice-free conditions. We used repeat terrestrial laser scans combined with change detection during the summer of 2019 to quantify rockfall activity over a 0.7 km² rock wall area along the ablation zone lateral margins of the debris-covered Miage Glacier, Italy. We detected 2,581 rockfalls spanning eight orders of magnitude (10⁻³–10⁴ m³; median 0.021 m³) including an event of about 28 × 10³ m³ from a newly deglaciated slope. Large rockfalls (≥10 m³) on lower, glacier-proximal slopes, whilst infrequent (<1% by count), achieved the most geomorphic work. Most (79%) rockfalls originated within <75 m above the glacier surface (mAG; representing 29% of the survey area); a boundary that corresponds with the Little Ice Age trimline. Some rockwalls exhibited a secondary zone of higher rockfall activity at about 125–150 mAG, revealing a second trimline with a millennial-scale signal of elevated rock damage possibly associated with ice surface dynamics during or immediately after the Younger Dryas Stadial. Modelled rockfall runout distances were determined in part by path topography: rockfalls originating from lower slopes travelled <100 m horizontally whilst those originating higher could travel up to 650 m, approaching the glacier centreline, reflecting a spatial differential in hillslope-glacier connectivity that will evolve concurrently with cryospheric degradation in the wider catchment. We show that detailed, short-term monitoring campaigns can yield novel and useful descriptions of mass movement fluxes and spatial patterns in alpine regions. Expanding our dataset by observing rock walls near the equilibrium line altitude could help bridge the longitudinal gap to existing high elevation inventories to provide a more unified picture of rockfall dynamics in deglaciating catchments.

Fine-grained sandy and gravel beaches are highly sensitive coastal zones, shaped by complex interactions between natural processes and anthropogenic pressures. Long-term monitoring of coastal dynamics is essential for effective and sustainable management of these environments. This study focuses on the long-term (64-year) coastal dynamics of Sušac Beach, located on the northeastern part of Pag Island, Croatia, within a karst landscape. The research combines historical aerial imagery (HAIs) with very-high-resolution UAV photogrammetry to analyse spatio-temporal changes (STCs) in beach morphology. The primary objectives were to quantify long-term linear and areal STCs using HAIs and to assess short-term (6-month) volumetric changes using UAV surveys conducted with the DJI Matrice 210 RTK.

Sušac Beach exhibited intense coastal dynamics over the 64-year period, but no significant long-term linear or areal retrogradation was observed. Despite extensive morphological changes, the beach's overall size remained stable, indicating long-term resilience. Short-term analysis revealed substantial volumetric changes, with dominant erosion (177 m³ of material eroded) and a net material loss of 99 m³. The study suggests that continuous sediment replenishment from surrounding steep slopes contributes to the beach's stability over time. The combination of HAIs and UAV photogrammetry proved effective in monitoring linear, areal and volumetric STCs, providing valuable insights into coastal dynamics on a beach at the flysch–carbonate contact.

The findings highlight the importance of natural sediment supply in maintaining beach stability, even in the face of intense short-term erosion. The study also underscores the utility of integrating archive historical imagery with modern geospatial technologies for comprehensive coastal monitoring. This approach can be applied to other similar beaches, offering a robust framework for understanding and managing coastal dynamics in sensitive environments. The results contribute to the broader understanding of coastal processes and provide a foundation for future research on the impacts of climate change and anthropogenic activities on coastal systems.

Mass movements can be triggered abruptly by precipitation and snowmelt and represent potential geohazards. In the polar regions, they are an important contributor to geomorphic change. This study examines a series of slushflows that occurred on Disko Island, Central West Greenland, in July 2023. These rapid mass movements are linked to an atmospheric river event that caused extreme precipitation, markedly increasing snowmelt and runoff. Pre- and post-event remote sensing imagery were used to map the affected areas, while environmental monitoring data and climate reanalysis products provided insights into the atmospheric river event. Almost 200 slushflows were mapped in Disko Island alone. During the 18-hour event, cumulative precipitation reached 115 mm, with more than 80 mm in several parts of the island, coinciding with the areas most affected by debris and snowpack mobilization. Increasing air moisture transport caused by atmospheric rivers has already been recognized as a contributor to a warmer and wetter Arctic. This work shows how extreme rain-on-snow events can trigger rapid mass movements with strong potential impact on landscape and infrastructure, suggesting the need for increased monitoring in remote areas such as Greenland.

Landslides, intensified by climate change, pose a growing threat to human life, yet studies on their direct human impact remain limited. This study introduces an advanced framework for assessing human risk from rainfall-induced landslides, focusing on Ba To, a landslide-prone district in Quang Ngai Province, Vietnam. The framework follows six key steps: (1) assessing landslide spatial probability using deep neural networks, (2) evaluating temporal probability with Monte Carlo simulation and infinite slope modelling, (3) estimating hazard by combining spatial and temporal probabilities, (4) analysing landslide propagation via Flow-R software, (5) determining population density in building areas and (6) calculating human risk using a hybrid quantitative–semi-quantitative approach. Each step was validated against real landslide data, confirming the model's reliability. The framework effectively quantifies human risk and estimates risk for different return periods, improving landslide risk assessment and aiding decision-making in disaster management.

This study proposes a fluid dynamic parameter to evaluate the performance of sand barriers. Using a cellular automaton model, the migration of barchan dune chains in the presence of different types of non-porous sand barriers is simulated. A temporal indicator characterising the sand barrier's sand-blocking effect is introduced to evaluate the effects of the cross-sectional shape and aspect ratio of the sand barrier. Furthermore, a fluid dynamic parameter—the singular value σ₂ characterising the energy of the second-order proper orthogonal decomposition (POD) mode—is proposed via POD to combine the geometric characteristics of the sand barrier with the kinetic characteristics implied by the surrounding flow. It is found that this parameter is negatively correlated with the sand-blocking effect, which is supported by the test that changes the height of the sand barrier. Therefore, the proposed fluid dynamic parameter can provide a reference for the design of sand barriers in sand control projects.

The improvement of subsurface prospecting techniques, such as ground-penetrating radar (GPR), has substantially enhanced many of the existing facies models for barrier islands. However, there is still much to be refined in terms of controlling factors underpinning barrier evolution, such as the processes responsible for sand transport and the roles of inherited topography and climate change. This study presents the results of facies-architectural and sedimentological analysis conducted along the northern sector of the Castle Neck barrier island (Massachusetts, USA).

A regional grid of 16 radar sections was acquired along shore-parallel and shore-normal transects and combined with sedimentologic data derived from augers and vibracores to ground-truth time-depth conversions and verify stratigraphic units inferred from the GPR-reflection profiles. Eight facies associations (RF1–RF8) were characterized and interpreted from GPR and core data, and associated vertical and lateral distributions were evaluated in order to reconstruct the evolution of the barrier island. Six associated evolutionary stages were defined, though not all are recorded along the entire shoreline, indicating likely periods of erosion or non-deposition along sections of the beach.

Our data show how alongshore-variable island development has been strongly influenced by inherited glacial topography, particularly the presence of drumlins, which partitioned the barrier into distinct northern and southern sectors. The northern sector is characterized by nearshore and dune deposits resting directly on glacial facies and shows evidence of bar welding and phased growth associated with inlet sediment bypassing processes. The southern sector evidenced the rotation of the paleo-inlet of the Ipswich River towards its present-day nearshore-perpendicular orientation, with the channel deposits progressively covered by those associated with beach and nearshore progradation. This study confirms that the evolution of barrier islands cannot be understood solely by examining their internal record but must also consider regional factors such as inherited topography and inlet avulsion processes.

Bedform existence in shallow shelf seas is predominantly controlled by the surface sediment characteristics. However, the sediment characteristics might change following sediment extraction, as this exposes a currently burried layer. This study presents a method to use existing sediment data to map the median grain size and mud content in the current surface layer and the deeper layer, to quantify the change between the layers and to analyse how this change might affect sand wave occurrence. When applied to the Netherlands Continental Shelf, this reveals that, on average, the deeper layer contains finer (230 versus 219 μm) and muddier (1.7 versus 1.3%), although local variations can be considerable. Furthermore, our results suggest that the potential exposure of the deeper layer might reduce the sand wave area by 300 km².

River deltas are vital for human development and ecosystems, and understanding their long-term morphodynamics is a prerequisite for better management and adaptation under climate change. The modern Yellow River Delta (mYRD), starting to develop since 1855, is one of the youngest large river deltas on the globe, providing an excellent case exemplifying how a river delta evolves and transitions over a century in response to huge fluvial sediment supply and drastic sediment reduction. In this contribution, we reconstruct mYRD's 170-year morphodynamic development based on the integration of historical maps, satellite imagery, bathymetric and hydrological datasets. In-depth data analyses show continuous delta growth with a seaward shoreline aggradation rate of 197 ± 3 m year⁻¹ and a subaerial area increase rate of 27.1 ± 2.2 km² year⁻¹ in the first 125 years (prior to 1985) under a mean fluvial sediment supply of 1400 Mt year⁻¹. Afterward, a sediment decline of 90% induces a transition change from delta aggradation to degradation, with a subaerial land loss rate of 4.5 ± 0.7 km² year⁻¹ between 1985 and 2002. The subaqueous delta underwent a deposition-to-erosion shift change in 2003, with net deposition and erosion rates of 160 and 440 Mm³ year⁻¹, respectively. The mega-delta buildup rate of the mYRD is outstanding in the global context, showcasing how fast delta development could be under excessive sediment supply. Moreover, the afterward aggradation-to-degradation transition implies the risk of delta erosion and shrinkage once sediment supply reduces to a threshold below which erosion and land loss surpass accretion and land formation. These findings inform the necessity of integrative sediment management strategies to mitigate delta erosion and habitat loss at the decade to century time scales.