Earth Surface Processes and Landforms最新文献

Seasonal variations in proglacial lakes are often omitted from long-term records of lake behaviour due to the trade-off between high-spatial versus high-temporal resolution satellite imagery. Understanding the impact of these short-term fluctuations on long-term studies of proglacial lake growth is essential for accurately predicting future growth, as well as for understanding the risk of jökulhlaups or glacial lake outburst floods (GLOFs). Here, we use high spatial resolution (3.7 m) PlanetScope imagery to detect short-term variations in the area of Fjallsárlón, a large proglacial lake in southeast Iceland. We demonstrate that between 2017 and 2023, moderate resolution imagery underestimates seasonal variations in lake behaviour by ~7% compared with PlanetScope imagery. In addition, the use of a single image from summer months (June to August) underestimates the annual maximum lake area by up to ~2%. The omission of these short-term variations in longer-term studies risks misrepresenting patterns of lake growth and behaviour, which has implications for glacier retreat, contribution to sea level rise and downstream flood risk from GLOFs.

This study investigates the interactions between sediments and biota in the Mariuá Archipelago, a mega-complex anabranching reach of the Negro River, the main blackwater river in the Amazon Basin, to understand the dynamics of the ecosystem in cratonic systems with limited supply. Using satellite imagery and hydrological data (2019–2024), we characterized suspended sediment concentration (SSC) patterns and evaluated geomorphological controls on habitat stability. Results revealed minimal inter-channel SSC variation (6.53–7.32 mg.L⁻¹) across the archipelago, contrasting sharply with sediment-rich Andean tributaries. Annual suspended sediment flux decreased 23% through the archipelago (4.48 × 10⁶ ton.year⁻¹ upstream to 3.38 × 10⁶ ton.year⁻¹ downstream), indicating net retention of 1.10 × 10⁶ ton.year⁻¹ within inter-island lakes and floodplains. The low specific sediment yield (12–15 ton.km⁻².year⁻¹) and the contemporary sedimentation rate (0.10 ± 0.05 mm.year⁻¹) contrast with Middle Holocene formation conditions, when the Negro River had higher energy and a greater sediment concentration than at present. Low correlations between SSC, water discharge and precipitation (r ≤ 0.51) demonstrate limited environmental forcing in this cratonic landscape. Spatial analysis reveals that downstream lakes function as suspended sediment sinks, concentrating fine particles during low-water periods and supporting distinct aquatic plant communities. This supply-limited regime enables ecosystem stability through reduced sediment-mediated disturbance, maintaining persistent habitats for endemic biota since the Pleistocene. However, mining, deforestation and climate change threaten this equilibrium by potentially increasing suspended sediment inputs beyond historical ranges. Geomorphological constraints in ancient cratonic systems promote long-term ecological stability, rather than disturbance-driven dynamics. This study provides new insights for the conservation planning of fluvial ecosystems in this unique landscape.

Isla, M.F. FitzGerald, D.M. Dougherty, A.J. Buynevich, I.V. Hein, C.J. Black, S. 2025 Refining the evolutionary model of a barrier island (Castle Neck, Massachusetts): A complex interaction with tidal inlet processes Earth Surface Processes and Landforms 50 15 e70225 https://doi.org/10.1002/esp.70225

In the author list, Amy J. Dougherty's affiliation “School of Earth and Environmental Sciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia” was incorrect. This should have read: “Center for Teaching & Learning Design, Stockton University, Galloway, New Jersey, USA.”

We apologize for this error.

Vegetated sand dunes are not typically considered to be significant sources of dust because of coarse grain sizes and high vegetation cover. Yet, plumes of dust have been observed from vegetated dune fields, and wind tunnel experiments show the potential for interdunes to emit dust. The partially vegetated southwest Kalahari is one such dune field that is vulnerable to climate-driven land degradation and vegetation cover change and has been posited as a potential future dust source. In this study, we monitor the post-fire de-vegetated state of 11 interdunes to investigate the dust emission potential and erodibility controls on emission. Findings suggest that there is little emission of dust despite a fine-grain component (up to 30% of resident grains <62.5 μm) and a lack of vegetation, even with high velocity wind events (>7 m s⁻¹) post-fire. Erosive wind events were less frequent compared to other dust-producing regions, with wind speeds generally under 7 m s⁻¹. Five high wind speed events over 7 m s⁻¹ were recorded in September 2022, the month immediately following burning, but even then, only one event had a concurrent increase in aerosol concentration. This is indicative of other erodibility factors limiting dust emission. These include high (>50%) burned debris cover in the immediate post-fire period and evidence of biological soil crusts that survived burning. Both protect the surface after fire whilst the natural vegetation cover recovers. Combined, the general low wind speeds, high initial surface cover, and the protective effect of biocrusts result in a low probability of the southwest Kalahari emitting dust post-fire. However, fine-grain sizes and low vegetation cover under drought and high grazing may lead to conditions conducive for dust emission.

Scour holes are common features in river deltas formed by a combination of hydrodynamic and geotechnical conditions. While previous studies have primarily focused on their long-term evolution toward equilibrium, their response to a single flood wave remains relatively underexplored. This study makes use of a unique, extensive dataset of frequently measured bed levels in the Dutch Rhine Delta to investigate the short-term behaviour of scour holes.

The analyses reveal that scour hole behaviour can be divided into two categories: dynamic and stable. We propose a conceptual model to describe this behaviour. Dynamic scour holes show large fluctuations in area, depth and volume caused by seasonal discharge variations. These temporal fluctuations exceed annual growth rates. By contrast, stable scour holes show virtually no variations in shape and dimensions. They are generally smaller in area but almost twice as deep as dynamic scour holes. Their large depths and steep slopes prevent sediment from being transported up the slopes, showing a stabilisation in depth.

Dynamic scour holes are typically located in upstream river reaches, where the sandy beds and engineering works allow for significant erosion and aggradation. Stable scour holes are found in tidal river reaches, where peak discharges are attenuated. Due to the absence of these peak discharges, combined with a strong heterogeneous river bed composed of easily and hardly erodible layers, growth in area is limited.

Tropical glaciers are important indicators of climate change, provide freshwater resources for downstream communities, and form an important component of the hydrological cycle. Understanding the dynamics and patterns of behaviour of tropical palaeoglaciers is important for interpreting their sensitivities and vulnerabilities. Glacier advances in the high tropical Peruvian Andes occurred multiple times during the last glacial cycle and Holocene, leaving complex geomorphological evidence on the landscape. The substantial topographic, geological and climatic variability in this region leads to high geomorphic diversity. However, few detailed geomorphological studies have been conducted to date, leading to considerable uncertainty in the behaviours and drivers of tropical palaeoglaciers. Here, we provide a detailed geomorphological analysis of the Cordillera Vilcanota, Cusco region, southern Peru (71°W, 13.7°S), and use morphostratigraphic principles to reconstruct the former maximum icefield extent and palaeoglacier advances. Across this domain, we mapped ~23,000 features encompassing five key environments: glacier, subglacial, ice-marginal, fluvial and lacustrine. The mapped features show evidence of both modern-day polythermal and temperate ice margins, with low meltwater volumes leading to small-scale glaciofluvial landform formation. However, larger moraines, beyond those well-dated to the Younger Dryas and Antarctic Cold Reversal, assumed to represent Last Glacial Maximum and earlier advances, suggest that conditions were temperate and drained by more substantial rivers, with coupled flow of ice and till, and evidence of subglacial scouring, drumlin formation and the deposition of substantial moraines and large palaeosandar. Our reconstructed maximum icefield covers 2,660 km² and was drained by multiple topographically constrained ice lobes across the region. In the north, these ice lobes reached an elevation of 3,500 m asl, but were limited to above 4,500 m asl in the south, likely reflecting the dominant moisture sources. Our geomorphological mapping reveals seven clear ice margins, morphostratigraphically correlated across the study region, reflecting at least seven palaeoglacier advances during the last glacial cycle, including the Late Glacial period and the Holocene.

Large wood (LW) entrainment and transport observations of naturally occurring wood in rivers are critical for understanding wood dynamics. However, they remain limited and sparse, primarily originating from single-site studies. As a result, broader spatial or temporal variability of wood dynamics may not be adequately captured. We compiled a database of tracked, natural pieces of wood from 11 low-order and relatively steep streams in the Chilean Andes, Swiss Alps, United Kingdom and United States. From decades to single-year studies, we gathered 59,739 observations of tracked wood, which all include at least a recorded length and transport distance. River characteristics varied according to channel width, less than 5 m to wider than 15 m, and gradient, between < 0.02 and > 0.04 m/m. The meta-analysis enabled us to calculate probabilities and identify general patterns. Wood mobilization varied significantly interannually, reflecting the complex interplay between flood events and wood storage. Overall, a small proportion of tagged wood moved during study periods, primarily during events associated with return periods exceeding 10 years. Most mobile pieces travelled less than 1 km, and longer distances had relatively low probabilities, typically occurring during high-magnitude flood events associated with return periods over 10 years. Results showed that large wood mobility in rivers is generally infrequent and highly variable, influenced by a combination of wood characteristics, river size and flood magnitude. Understanding variability can help inform risk-based flood hazard planning, river management and river restoration projects implementing large wood. Future studies should expand upon the current dataset.

Permafrost creep is manifested by the presence of rock glaciers in mountainous areas, which are climatically driven landforms. Under degrading permafrost conditions, these ice-rich bodies tend to slow down until deactivation through a transition phase. However, the ongoing processes and their associated geomorphic responses remain are still poorly understood. This study aims to better understand the relationship between their activity, topo-climate conditions, and associated geomorphic responses of transitional rock glaciers. The activity of 520 landforms in the French Alps was assessed through Differential Interferometry Single Aperture Radar (DInSAR). Kinematic attributes were then correlated with topo-climatic and geomorphic characteristics using statistical exploration (Multiple Correspondence Analysis, MCA) and modelling (Multinomial/Binomial Logistic Regression, MLR/BLR). Results show that 71% of rock glaciers are stabilized or slow-moving landforms, while 23% exhibit surface velocities greater than 10 cm/year. Both MCA and MLR/BLR highlight that fast-moving rock glaciers are strongly correlated with higher latitudes, high elevations, steep slopes and convex morphologies, in contrast to slow-moving rock glaciers. MLR analysis revealed further differences between slow and fast classes. Rock glaciers with velocities <1 cm/year and 1–10 cm/year are located at lower latitudes and elevations, and in regions with unfavourable permafrost conditions. However, the <1 cm/year class is still found on steep slopes, suggesting that these landforms may not contain enough ice to maintain permafrost creep. Rock glaciers with velocities between 1 and 10 cm/year are more likely on smoother slopes, but they also show high occurrence probabilities at high elevations, indicating dynamic deactivation processes. Finally, the 10–30 cm/year class is slightly more probable under unfavourable permafrost conditions, which may suggest ongoing climatic deactivation. High-speed ranges were also associated with heterogeneous and small-moving areas within rock glacier systems, suggesting the presence of restricted permafrost conditions within a deactivating system. This finding raises important questions about spatial transitions and the temporal evolution of such kinematic behaviour.

Landslide activity in the Qilian Mountains is increasing due to permafrost thawing driven by global warming, where also developed numerous reverse strike-slip active faults with frequent and high-intensity earthquakes. While many studies have examined the influence of climate change on landslide activity in permafrost regions, the role of earthquakes in modulating landslide behaviour in such environments remains less well quantified. In this study, Interferometric Synthetic Aperture Radar (InSAR) was employed to investigate whether the 2022 Menyuan earthquake induced post-seismic acceleration of landslides in permafrost areas. The results show that the earthquakes exerted a pronounced impact on landslide deformation, producing an instantaneous subsidence of approximately 24.83 mm, which is substantially larger than the maximum annual displacement observed before the event. Moreover, post-seismic landslide velocities increased by up to 21 mm/year, and the seasonal deformation amplitude after the earthquake was approximately twice that observed during the pre-seismic period. To further elucidate the mechanisms underlying these responses, we quantified the dominant controlling factors of landslide deformation using a Geographic Detector approach. The results indicate that landslides located closer to active faults exhibit larger displacement rates, although no clear hanging-wall or footwall effect was observed. Landslides at higher elevations, particularly above 3,450 m, are more susceptible to deformation. Importantly, we find that landslides under colder ground temperature conditions are more strongly affected by seismic shaking and tend to exhibit larger post-seismic deformation, with a 0.2°C decrease in ground temperature corresponding to an increase of approximately 5 mm/year in displacement rate. These findings provide new quantitative insights into the role of earthquakes in controlling landslide activity in permafrost regions and highlight the importance of permafrost thermal conditions in modulating post-seismic landslide behaviour.

The primary drivers of river morphology and dynamics are the hydrologic and sedimentologic regimes, but the wood regime is also important. Fallen wood will typically float at the water surface during floods, and the movement and deposition of large pieces can alter the trajectory of sedimentary bedforms, aquatic habitat, and flood hazards. Accurate quantification of floating wood in rivers is now possible, which is enabling us to better understand the role of this key variable, but frequency analysis is rare due to the relatively recent application of monitoring methods and a lack of standard analytical methods. The current study assembles the longest and most complete record of riverine wood transport yet available. Specific objectives are to (a) synthesize and validate a long time series of wood transport from available observations using a neural network model and (b) describe the probability of wood transport events at a river station. The wood record was assembled from manual observations of large wood in multiple flood events and an automated analysis of the full video record, which was estimated to have a precision of 85% and recall of 86%. The neural network predicted wood transport volume from climate and hydrologic records and was found to have Nash-Sutcliffe efficiencies of over 75%. Comparison of model predictions with wood-mobilization estimates from aerial photos were within 30% for 5–10 year periods and 2% for a 40-year period. The wood regime was characterized with (i) an assessment of seasonality; (ii) a rating curve of wood volume from event peak discharge; and (iii) an extreme event analysis of daily maximum and yearly wood transport volume. The methods are useful for characterizing a river's large wood transport regime and hindcasting historical wood mass transfer from flow records. This information will help to understand river dynamics and facilitate sustainable river management.