Earth Surface Processes and Landforms最新文献

The pore space characteristics of geological materials are closely related to their mechanical, transport and hydraulic properties. In geomorphology, pore size distribution (PSD) is an important characteristic in rock weathering, evaporation and other studies. In an effort to find novel methods to determine the PSD, perhaps to bypass the disadvantages of the current techniques, there has been a growing interest in the use of non-Newtonian fluids. In this contribution, we are particularly interested in the method recently introduced by Abou Najm and Atallah (the ANA method), which exploits the way in which the flow of different shear-thinning fluids distributes differently in the pore space to compute the functional PSD estimation. We performed a set of saturated flow experiments with aqueous xanthan gum solutions of different concentrations, using as simple as possible laboratory settings, and we implemented a modified version of the previously introduced numerical model to obtain the PSDs of four sandstone and one tuff samples. The results are compared with conventional mercury intrusion porosimetry, showing a good agreement regarding the dominant pore size and a notable similarity in the distributions. Several limitations were identified as well, such as the lack of information on relatively small pores (<5–10 μm for the samples studied) and the potential issues in obtaining a more detailed distribution. We conclude that the ANA method is promising for geomorphological evaporation and rock durability studies, particularly for coarser materials such as sandstone, but it also encounters challenges for certain applications, especially for fine-grained rocks. It must be acknowledged that the ANA method has been tested on a limited range of materials and further investigation is required to fully explore its capabilities and limitations.

The morphology of the coastal landscape in transitional environments results from the gradual and complex dynamics of natural processes at different scalarity, capable of elaborating and remodeling the relief. Their arrangements and interactions are reflected in the configuration and evolution of the landscape and waterscape governed by allogenic factors (climate, tectonics and, more recently, anthropogenic) generating autogenic responses in environmental systems. In this sense, several studies have demonstrated the importance of sea level oscillations, sedimentary balance and river-coastline displacements associated with climate fluctuations during the Quaternary. However, there is still a relative lack of recent research that focuses on the last glacial maximum (LGM) and the Holocene for the eastern Brazilian coast. In this way, the intense morphodynamics between estuarine and deltaic systems could become interpretative keys in the general understanding of these environments worldwide because they are located in a particular context within the connectivity of these geomorphological systems. To investigate these processes between the Jequitinhonha, Pardo and Una Rivers, detailed mapping and geomorphic topographic profiles were carried out using pre-selected digital elevation models, and fieldworks were carried out on land and water to validate the mappings and to collect samples. Then, they were subjected to geochronological analysis using Optically Stimulated Luminescence and grain size distribution to recognize the depositional age and characterize the surficial cover. It was possible to identify five depositional landscape units: fluvial terraces, fluvial-marine terraces and three staggered levels of marine terraces. Based on these results, a paleogeographic reconstruction of the evolutionary phases of this eastern sector of Brazil's coast was carried out, chronologically covering the Pleistocene/Holocene transition up to the present. The aim is to understand littoral dynamics as a response to both fluvial adjustments and oscillations of the regional relative sea level.

Rivers represent intricate geomorphological systems that exhibit sensitivity to even subtle base-level changes. This study examines the geomorphological response of Ribeira de Iguape River, located along the southern coast of São Paulo state, Brazil, to hydrological changes and coastline migration resulting from Holocene climate pulses. Using a multidisciplinary approach, including geomorphological and stratigraphical analyses, optically stimulated luminescence dating, grain-size analyses, interpretation of satellite images, mapping and reassessment of previous studies, we investigated the potential impacts of these geomorphological dynamics on the river system. Our study reveals two distinct orders of low fluvial terraces, typically inserted no more than 10 m above the average channel discharge, which are geochronologically correlated with the low marine terraces that document the former coastline position at the river mouth, as previously identified in other studies. Such findings indicate a deposition phase when the coastline was stabilised on the inner continent in the Medieval Warm Period, as well as an erosion phase when the coastline migrated seaward during the Little Ice Age. This research contributes to improving our understanding of how rivers can respond to base-level changes and provides valuable insights into the dynamic interactions between river systems and coastal environments.

Soil erosion on bare slopes in coastal reclamation areas reduces the efficiency of water conservation projects and poses a threat to the water environment in saline tidal flats. Slope shape and soil hydrological conditions are affected by severe soil detachment and rapid sedimentation processes during rainfall, which in turn influence soil erosion processes. In this study, the influences of slope gradient, slope length, initial soil water content and groundwater depth on slope erosion processes of saline sodic soils were investigated through simulated rainfall experiments. We found that the effect of slope gradient on soil loss varied with slope length. For the long-slope treatments with the same total length of initially air-dried soil (AD), the unit width sediment yield rate (Rs) significantly (p = 0.05) increased with increasing slope gradient from 30° to 60°. For the short-slope treatments with different total lengths, opposite trends were observed for the runoff rate and Rs variation with increasing gradient. The Rs values of the slopes with initially saturated surface soil (SS) and a groundwater depth of 0.8 m (GW) were significantly (p = 0.05) greater than that under the AD treatment. On the 60° SS treatment slopes and 45° and 60° GW treatment slopes, soil erosion induced distinct collapse failure and altered the original slope shape, yielding lower gradients and larger lengths, which significantly (p = 0.05) increased Rs in turn. Canonical correlation analysis (CCA) revealed that 71.6% of the variance in the set of dependent variables (sediment yield and runoff) could be explained by the first pair of canonical variables, which mainly represented slope topography factors, and 12.1% of the variance could be explained by the second pair, which mainly represented soil hydrological conditions. The conclusions of this study could provide a theoretical foundation for slope protection in coastal reclamation areas.

The expansion of glacier-free forelands after glacier retreat is emerging as a typical climate change-dependent feature that is widely studied for assessing biogeomorphic feedbacks and analysing the vertical processes and changes occurring in the critical zone (CZ). However, the horizontal processes occurring in the CZ environment are still poorly understood. Here, we comprehensively analyse the development of the CZ environment over time in the Forni Glacier forefield, Italian Alps, since the end of the Little Ice Age (LIA) by considering different sectors (air, forest, water and soil) in two portions of the glacier forefield: the lower portion, which occurs below the glacier-forefield treeline (GFT), where a fully functioning CZ environment has developed, and the upper portion, which occurs above the GFT, in the proglacial area (PA), where only an incipient CZ exists. The early stages of CZ development in the PA are highly influenced by katabatic winds, which impact the colonisation patterns of saplings and young trees, and characterised by high-energy geomorphic processes that cause sediment reworking and initial stages of soil development. Below the GFT, the minimum tree ecesis interval after glacier retreat reaches a median value of 38 years (n = 8), and the fully developed CZ environment (with trees reaching at least 2 m in height after 20 years) formed after ~60 years following glacier retreat and is characterised by forest cover, soils organised in a chronosequence and contrasting isotopic signatures of surface and running waters. The correlation with the isotopic signatures of tree rings allowed us to estimate a groundwater flow period of approximately 2 months from the slopes into the CZ of the valley floor. By analysing the horizontal processes driving the geomorphic and biotic evolution patterns of a glacier forefield, this work introduces a novel approach for assessing the development of the CZ environment over time.

Gravel transport in subaerial environments occurs through different flows that are conveniently classified as debris flows, debris floods and water flows based on their distinct morpho-sedimentary dynamics and different implications for geomorphic hazard. Because distinctive features allowing gravelly sedimentary bodies to be ascribed to related genetic process are still a matter of discussion, this study aims to establish whether imbrication fabric represents a sedimentological fingerprint potentially applicable towards a more robust genetic classification of gravels. We analysed the fabric of 1007 imbricated clasts from modern and ancient deposits. Our results highlight statistically significant differences between imbrication fabrics in gravels deposited by different flows. Particles imbricated by water flows are typified by low imbrication angles (median of 35°) and elongated clasts oriented perpendicular to the flow. In contrast, debris-flow gravels exhibit high imbrication angles (median of 65°) and elongated clasts oriented parallel to the flow. Debris-flood deposits display elongated clasts both parallel and transverse to the main flow and intermediate values of imbrication angle (median of 47°). We propose that imbrication angles result from the combination of stability-driven selection—a process acting under tractional transport and promoting the remobilization of high-angle imbrication fabrics—and shear-stress-driven overriding—a mechanism leading to the formation of the higher imbrication angles—with the first dominating in water flows and the latter being effective in mass transport processes. The progressive change in imbrication fabrics from fluid-gravity to sediment-gravity flow deposits offers easily quantifiable sedimentological evidence to help in distinguishing genetic processes that contribute to the accumulation of gravels in alluvial and colluvial settings. Analysis of imbrication fabric can add valuable information, particularly as regards the classification of (1) coarse deposits in stratigraphic records and (2) modern debris flood deposits.

We analysed the elevated low-relief relict landscapes in the transient Upper Satluj-Zhada basin and the adjoining region in the tectonically active north-western (NW) Himalaya–south-western (SW) Tibetan orogen to understand the evolution of the regional landscape and drainage system under the influence of the Karakoram Fault-Leo-Pargil Horst system. This elevated low relief landscape represents the Mio-Pliocene establishment of a new river network, which testimonies the present Sutlej River, which has been experiencing a transient surface uplift-incision regime since (~4–1 Ma) with a local base level at the confluence of the Sutlej and Spiti River. The Miocene exhumation of the Ayilari Range and Leo-Pargil Horst across the Karakoram fault (KF) system led to headward erosion, which abandoned the Paleo-Sutlej-Indus drainage system, which in turn caused drainage reversal along Qusum detachment (QD) and produced southward migration of the Paleo-Sutlej River towards the mountain front. Our results indicate that the Upper Indus River has significantly lower χ-ranges at higher elevations as compared with the adjacent Upper Sutlej River at lower elevations, which corresponds with a river piracy model that incorporates area gain-loss feedback. The Upper Sutlej River in the Zhada basin is characterized by a comparable series of coplanar slope-break knickpoints at ~4000–4500 m elevation, and their adjoining divides are in a state of disequilibrium as a consequence of the very high rapid incision across the Leo Pargil Horst, which drives the regional gradation process. The headward-eroding Upper Indus River captured the proto-Sutlej due to a base-level change of >~1500 m, which significantly impacted the regional growth pattern and tectonics. The Mio-Pliocene sedimentation pattern of the Upper Sutlej-Zhada basin in the SW Tibet–NW Himalaya reflects this regional drainage capture, tectonic uplift and paleo-drainage reorganization. The present finding has wider implications for the Mio-Pliocene reorganization of drainage systems and the possible linkage of the Upper Indus River with the Paleo-Sutlej over the Zhada basin.

Gijsman, R., Horstman, E.M., Swales, A., MacDonald, I.T., Bouma, T.J., Wal, D., Wijnberg, K.M. (2024) Mangrove forest drag and bed stabilisation effects on intertidal flat morphology. Earth Surface Processes and Landforms, 49(3), 1117–1134, https://doi.org/10.1002/esp.5758

In the Data Availability Statement of the ‘Open Research’ section, the authors missed the opportunity to mention that the hydrodynamic data that were specifically used for the calibration of the drag coefficients were obtained by the University of Waikato. The calibration of the drag coefficients is presented in Section S2 of the ‘Supporting Information’. For that reason, the authors would like to add the following sentence to the Data Availability Statement: ‘The hydrodynamic data that are used for the calibration of the drag coefficients are available from the University of Waikato upon reasonable request’.

Accordingly, in the ‘Acknowledgements’, the authors would like to adjust the sentence ‘Pressure, profile and vegetation data was partly obtained in prior field campaigns funded by the Royal Society of New Zealand's Marsden Fund (grant 14-UOW-011)’ to ‘Pressure, profile and vegetation data were partly obtained in prior field campaigns by EMH, Karin Bryan and Julia Mullarney (University of Waikato), funded by the Royal Society of New Zealand's Marsden Fund (grant 14-UOW-011)’.

The authors apologize for this inaccuracy.

Soil loss is a common land degradation process worldwide, which is impacted by land use and climate change. In this study, random forests (RF) were first used to establish a soil loss model at the scale of a small watershed in the hilly-gully region of the Loess Plateau based on the field observation data. Subsequently, the model was used to predict soil loss in the Chabagou watershed under the historical (1990–2020) and future emission scenarios, namely SSP1–2.6 (low-emission), SSP2–4.5 (medium-emission) and SSP5–8.5 (high-emission) (2030–2,100) from the Coupled Model Intercomparison Project Phases 6 (CMIP6). In the RF model, the coefficient of determination (R²) and Nash-Sutcliffe coefficient of efficiency (NS) were both greater than 0.86, and the RMSE-observations standard deviation ratio (RSR) was less than 0.36. Additionally, the RF-based model had higher simulation accuracy and robustness than those of the previous soil loss models, indicating its potential for wider applications in simulating soil loss. Compared with soil loss between 1990 and 1999, climate change led to a 35.36% increase in soil loss, while land use change resulted in an 11.13% reduction from 2000 to 2020 in the Chabagou watershed. This reveals that the current land use management could not effectively counterbalance the soil loss caused by rainstorms. Furthermore, compared with the historical period (1990–2020), under SSP1–2.6, SSP2–4.5 and SSP5–8.5 (2030–2,100), the soil loss rates without land use change would be increased by 6.01%, 19.11% and 35.35%, while the soil loss rates with land use change would be changed by −5.88%, +4.41% and +19.12%, respectively. These results help to provide a scientific basis for enhancing the capacity to respond to climate change and mitigation of soil and water loss on the Loess Plateau.

The Shuttle Radar Topography Mission (SRTM) is a digital representation of the terrain surface morphology that contains rich terrain information and is widely used in environmental analyses. However, SRTM is adversely affected by mixed noise, which typically include random and stripe noise. Mixed noise results in the significant loss of topographic information, which reduce the validity of related research. To eliminate mixed noise in SRTM data, we propose an adaptive low-rank group sparse model based on edge preservation (ALGS_EP) to remove mixed noise from datasets. The method relies on a low-rank group sparse model that considers the gradient features of the terrain. It calculates a terrain factor to adapt the noise elimination model to terrain changes. Additionally, it integrates with the edge structure of elevation data and applies a double-gradient constraint to preserve the structural details of the elevation data. The proposed model, built upon the alternating direction multiplier method framework, enhances the traditional weighted kernel paradigm minimization algorithm by introducing variable weights that adjust according to the gradient of elevation data during iterations. Additionally, it incorporates the correlation between strip noise and residual data blocks when computing the iteration count, ensuring an iterative solution approach that converges to the optimal solution. We used ALGS_EP to process global SRTM 1 data and published a higher-quality and higher-precision elevation dataset. The elevation data noise before and after noise elimination were statistically analyzed. Simulated and empirical results show that the model is highly robust and more effective than existing methods in both visual and quantitative evaluations. The noise elimination rate was 97.6%, compared to the original data. Therefore, this research was valuable for applications that use digital elevation model as an important data layer.