Earth Surface Processes and Landforms最新文献

{"title":"Rare earth element characteristics of Holocene sediments at the southern margin of the Gurbantunggut Desert and their implications for provenance","authors":"Yunqiang Ma,&nbsp;Zhizhong Li,&nbsp;Dianjia Tan,&nbsp;Xiaojun Zou,&nbsp;Tonglian Tao","doi":"10.1002/esp.70022","DOIUrl":"https://doi.org/10.1002/esp.70022","url":null,"abstract":"<p>The identification of Holocene sediment provenance at the southern edge of the Gurbantunggut Desert is of great significance for understanding the interaction processes of regional wind and water forces, the evolution of river-dune landform patterns and the atmospheric circulation change in the Junggar Basin. In this study, three aeolian-alluvial stratigraphic profiles in the desert-oasis transition zone at the southern edge of the Gurbantunggut Desert and different types of surface sediments in surrounding areas were taken as the research objects. Based on the chronological framework established by OSL dating, we analysed the REE characteristics, combined with grain size, quartz sand morphology and surface micro-texture features to explore the provenance change of Holocene sediments in the study area. The results indicated that there was no significant provenance change during the Holocene for alluvial deposits at the southern edge of the desert, which were mainly composed of detritus eroded and weathered by glaciers in the Tianshan Mountains. However, the aeolian sand may have undergone provenance change. From early to middle Holocene, detritus from the Western Junggar Mountains served as the sand provenance for dune development in the southwestern desert, with fine-grained components potentially being transported by westerlies, contributing to aeolian sand in the southeastern desert. During the middle to late Holocene, lacustrine sediments in the desert-oasis transition zone at the southern edge of the desert may have become an important source of aeolian sand. In the modern era, the Western Junggar Mountains continue to supply sand for dune development in the southwestern desert, while fine-grained components in the northern desert sand, transported southward by northwest wind, have, to some extent, influenced dune formation in the southeastern desert. However, Due to the limited transport capacity of the wind, we believed that only silt and finer components participated in and influenced the provenance change of the Holocene aeolian deposits at the southern edge of the desert. The results can provide a reference for studying the formation and evolution of the Gurbantunggut desert and preventing desertification in the future.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relative role of rock erodibility and sediment load in setting channel slope of mountain rivers","authors":"Naoya O. Takahashi","doi":"10.1002/esp.70017","DOIUrl":"https://doi.org/10.1002/esp.70017","url":null,"abstract":"<p>Rock strength influences channel slope by altering substrate erodibility and the size of sediments supplied to the channels. Although the frequent presence of knickpoints at lithological boundaries indicates that rock erodibility significantly determines channel morphology, a growing body of field evidence suggests that the coarse sediment supply from less erodible rock units is a primary factor in channel steepening. To assess the relative effects of rock erodibility and imposed sediment load on channel slope, I studied five rivers in Tsugaru, northern Japan. These rivers flow through alternating volcanic rock and sedimentary rock. The minimum channel slope required to transport both in situ sediments and those supplied from upstream was calculated using slope component analysis. The findings suggest that sediment effects largely account for the observed variations in channel slope across both volcanic and sedimentary rocks. The proportion of channel slope not explained by the imposed sediment load was slightly higher in volcanic rock reaches than in sedimentary rock reaches, which can be attributed to the lower erodibility of volcanic rock. Based on the grain size distributions of volcanic and sedimentary rock particles and the calculated impacts of sediment load, I conclude that the coarse sediment supply from volcanic rock is the primary cause of the difference in channel steepness between the rock types in Tsugaru. Although this conclusion holds generally true across Tsugaru, certain reaches with locally high channel steepness exhibit more extensive bedrock exposure than adjacent gentler reaches, suggesting that contrasts in erodibility also play a significant role in determining the channel slope. Therefore, examining what factors alter the relative significance of rock erodibility and sediment load can enhance our understanding of how rock properties influence longitudinal stream profiles.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/esp.70017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143446806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive temporal and spatial analysis of Early Pleistocene drainage patterns on the Swiss Alpine foreland","authors":"Ewelina Broś,&nbsp;Susan Ivy-Ochs,&nbsp;Thomas Pollhammer,&nbsp;Florian Kober,&nbsp;Reto Grischott,&nbsp;Bernhard Salcher,&nbsp;Jesper Nørgaard,&nbsp;Mads F. Knudsen,&nbsp;Christof Vockenhuber,&nbsp;Marcus Christl,&nbsp;Philip Gautschi,&nbsp;Colin Maden,&nbsp;Lotta Ylä-Mella,&nbsp;John D. Jansen,&nbsp;Angela Landgraf,&nbsp;Hans-Arno Synal","doi":"10.1002/esp.70000","DOIUrl":"https://doi.org/10.1002/esp.70000","url":null,"abstract":"<p>Deckenschotter are glaciofluvial gravels that cap isolated bedrock plateaus and are largely disconnected from today's local drainage. They were deposited when glaciers from the Alps were first extensive enough to reach the northern Swiss foreland, thus providing a unique record of the foreland landscape and its evolution during the earliest Quaternary glaciations. To decipher this record, we employ two robust methodologies: cosmogenic ²⁶Al/¹⁰Be burial dating and GIS-based topographic analysis. ²⁶Al/¹⁰Be burial ages from both new and published sites are calculated using a consistent procedure with the P-PINI code. Detailed swath projected and local 360° profiles were generated with GIS data in an R-toolset developed specifically for this study. Integrating results from both methodologies with outcrop sedimentological data, we interpret three main periods of Deckenschotter deposition: 1.3–1.2, 1.1–1.0 and ~0.8 Ma. The interpreted age ranges indicate glaciers must have reached the forelands in response to intensifying climatic cooling across the Mid-Pleistocene Transition (1.25–0.75 Ma). Deckenschotter outcrops provide a disjointed image of past topography from which we piece together glacial meltwater pathways in each time interval. Between the glacial phases, stepwise incision of 50–100 m occurred as depicted in the projection profiles, with some spatial variability in magnitude of incision. Incision was driven by decreasing sediment supply during glacial terminations, set against a backdrop of minor foreland uplift. While the path of the Aare River has changed little since the Early Pleistocene, the Rhine River has radically altered its path. Initially a tributary of the Danube River with northward flow, glacial modification to topography led to its re-routing to the west into the lower base-level Aare River-Upper Rhine Graben system. Based on our analysis, we estimate this event occurred after ~0.8 Ma.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoenvironmental context of fluvial soils in the dryest region of Brazilian semiarid","authors":"Patricia Dornellas Xavier,&nbsp;Rafael Albuquerque Xavier,&nbsp;Renan Figueiredo,&nbsp;Cláudio Vinícios Pedroso de Azevedo Andrade,&nbsp;Inocencio de Oliveira Borges Neto,&nbsp;José João Lelis Leal de Souza,&nbsp;Bartolomeu Israel de Souza,&nbsp;João Reis","doi":"10.1002/esp.70024","DOIUrl":"https://doi.org/10.1002/esp.70024","url":null,"abstract":"<p>Paleoenvironmental analysis in the Brazilian semiarid region is challenging. The low occurrence of flooded regions limits the preservation of pollen and accumulation of organic matter. In well-drained sites, the high pH and intense erosion destroy phytoliths. The low studies performed in limestone caves indicate that the semiarid climate conditions were established in the last 5 kyr before the present in Northeastern Brazil. In these conditions, alluvial deposits are potential sources of information about the recent past evolution of semiarid regions once the size, selection and composition of sediments reflect erosion and transport. This study aimed to analyse the recent past drainage evolution in the Borborema Plateau and Sertaneja Low Surface, two of the driest regions in Brazil. Four Fluvisols and one Cambisol were described in alluvial fans. Physical, chemical and sedimentological analyses were performed. Selected horizons were dated according to the OSL method. Variability of texture, mineral chemical composition and organic carbon content indicate discontinuities in all soil profiles. Layers of very poorly selected coarse material deposited in high-energy depositional systems are interbedded with clay-rich layers deposited by low-energy energy. The abundance of Fe, Si, Ti, Ca and K indicates variation in the source of the deposited materials. The age variation between the soil profiles indicates four evolutionary stages between 2,700 and ~100 yr. The higher age variance between layers in the Borborema Plateau indicates frequent and low-magnitude sedimentation events. These events are typical of semiarid climates because they reflect low sediment transport capacity by the ephemeral rivers. On the other hand, the lower age variation between the layers and buried A horizons suggest intense aggradation intercalated by stabilized periods, when vegetation was established and bioturbation formed A horizons.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of vegetation expansion on morphodynamics of tidal channel networks","authors":"Yin Zuo,&nbsp;Leihua Zhao,&nbsp;Xinchen Wang,&nbsp;Pei Xin","doi":"10.1002/esp.70023","DOIUrl":"https://doi.org/10.1002/esp.70023","url":null,"abstract":"<p>Evolution of coastal landforms, including the formation and development of tidal channel networks in salt marshes, is shaped by the interaction of surface water hydrodynamics, sediment transport and vegetation dynamics. However, the impact of vegetation expansion on tidal channel geomorphology remains unclear. In this study, an ecogeomorphic model coupling abiotic and biotic processes was developed to investigate the effects of vegetation expansion (i.e., seeding and cloning) on tidal channel morphodynamics. The numerical model results demonstrate that vegetation expansion promotes the formation and development of tidal channels. With vegetation cover, the number, total length, area and volume of tidal channels markedly increase. Vegetation also reshapes the cross-sections of tidal channels, increasing channel depths and decreasing their width-to-depth ratios. The synergistic effect of seeding and cloning is more significant than either process alone, leading to enhanced flow convergence and bed shear stress. Consequently, the channel erosion is enhanced, laying the foundational framework for the formation and growth of tidal channel networks. A high expansion rate enhances the effect of vegetation on tidal channel morphodynamics, leading to more developed tidal channel networks. This study focuses on tidal channel networks in salt marsh ecosystems and advances understanding of the geomorphological evolution of tidal channel networks subject to vegetation expansion, and it offers further implications for the management of coastal wetland ecosystems.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143424137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Downstream fining of fluvial gravels along the eastern Tibetan Plateau rivers","authors":"Zifa Ma,&nbsp;Yuanxu Ma,&nbsp;Xudong Zhao,&nbsp;Jiawei Zhang,&nbsp;Huiping Zhang","doi":"10.1002/esp.70016","DOIUrl":"https://doi.org/10.1002/esp.70016","url":null,"abstract":"&lt;p&gt;The downstream grain size variation along active river channels has been a long-standing topic for fluvial geomorphologists. However, identifying the influence and controls on downstream change in bed sediment texture is not straightforward. In this study, we investigated the lithological composition of bedrock and riverbed gravels, rock strength and grain size distribution of fluvial gravels within three active rivers flowing out of the Longmenshan Mountain in the eastern Tibetan Plateau where human disturbances are locally occurring, to examine the spatial pattern of grain size distributions and the controlling factors. The field investigations and geological mapping showed that granite lithology contributed more coarse clasts to the river bed substrate than its areal proportion. Downstream fining trends were detected across the entire river systems of all three rivers, while distinct patterns emerged when comparing upstream and downstream segments from the mountain front. The D&lt;sub&gt;50&lt;/sub&gt; of granitic gravels in the Yazi River (YZR) and Mianyuan River (MYR) have the same fining rate of about −0.013 km&lt;sup&gt;−1&lt;/sup&gt;, while the sandstone gravels in the YZR and limestone gravels in the MYR have a similar fining rate of −0.010 km&lt;sup&gt;−1&lt;/sup&gt;. In contrast, the granite and plagioamphibolite gravels in the Shiting River (STR) have higher fining rates, with values of −0.022 and −0.029 km&lt;sup&gt;−1&lt;/sup&gt;, respectively. For coarser grain size D&lt;sub&gt;84&lt;/sub&gt;, the granitic gravels in the YZR and MYR have similar fining rates between −0.018 and −0.019 km&lt;sup&gt;−1&lt;/sup&gt;, while sandstone gravels and limestone gravels have lower fining rates between −0.012 and −0.014 km&lt;sup&gt;−1&lt;/sup&gt;. Although the D&lt;sub&gt;84&lt;/sub&gt; fraction for granite and plagioamphibolite gravels has a higher fining rate of −0.034 and −0.022 km&lt;sup&gt;−1&lt;/sup&gt; in the STR, the D&lt;sub&gt;50&lt;/sub&gt; and D&lt;sub&gt;84&lt;/sub&gt; in STR have the same fining rate (−0.022 km&lt;sup&gt;−1&lt;/sup&gt;) for plagioamphibolite gravels. We interpret our data to indicate that selective deposition is the main control on downstream fining of fluvial gravels, as the mobility of gravel is strongly size-dependent. In addition, the higher downstream fining rates of both granite and plagioamphibolite gravels in the STR than those in the YZR and MYR also reveal the river channel slope control on the downstream change pattern of fluvial sediments. The significant difference in downstream fining rates between granite and plagioamphibolite gravels in STR indicates that the downstream fining in some reaches would be lithology-dependent. Although the weathering phenomenon on the surface of granitic gravels in river channels could not explicitly account for its contribution to the downstream fining of granitic gravels, its significance on gravel abrasion deserves further work in future investigations. Our field investigations show that human activities, such as gravel mining and dam construction, had temporal impacts on downstream grain size changes. Ou","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distinguishing the effects of vegetation characteristics on soil erosion process on the loess plateau of China","authors":"Jian Fang Wang,&nbsp;Yan Fen Yang,&nbsp;Bing Wang,&nbsp;Guo Bin Liu","doi":"10.1002/esp.70011","DOIUrl":"https://doi.org/10.1002/esp.70011","url":null,"abstract":"<p>Vegetation restoration significantly decreases soil erosion. Although runoff shear stress is not divided into grain and form shear stresses, the dynamic mechanisms of soil erosion remain unclear. To explore the dynamic mechanisms of soil erosion, two herbaceous plants, namely, <i>Bothriochloa ischcemum</i> (Linn.). Keng (BI) and <i>Artemisia vestita</i> Wall. ex Bess (AG), were planted at six planting densities of 5, 10, 15, 20, 25 and 30 plants m⁻² to obtain different vegetation characteristics. A simulated rainfall experiment (rainfall intensity of 1 mm min⁻¹) was conducted on runoff plots (length and width of 2.0 and 0.5 m, respectively), and the flow velocity, runoff rate and soil loss rate were measured. The results showed that the grain and form shear stresses ranged from 0.04 to 0.16 and 1.40 to 3.88 Pa under six planting densities, respectively. Grain shear stress decreased with planting density in both BI and AG grasslands. The form shear stress exhibited a greater magnitude in BI grasslands at a lower planting density, whereas in AG grasslands, the highest form shear stress was observed at a planting density of 20 plants m⁻². Vegetation can significantly reduce soil loss. Compared with that in bare soil, soil loss amount in the BI and AG grasslands were 68.08 to 95.08% lower. The reduction in soil loss amount was enhanced by the increased planting density. The BI grasslands were more effective in reducing soil loss than the AG grasslands. The amount of soil loss was mainly influenced by the interaction between vegetation and runoff characteristics, which explained the majority of variation (49.48%). The total soil loss increased with increasing grain shear stress and decreased with increasing vegetation coverage, root collar area and soil organic matter as a power function. With increasing total runoff, total soil loss increased linearly. Finally, the amount of soil loss was simulated using the grain shear stress, root collar area, soil organic matter and total runoff. The performance of the model used in this study was satisfactory.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatiotemporal changes of desertification areas in the Alxa Desert obtained from satellite imagery","authors":"Ting Li,&nbsp;Yuanwei Wang,&nbsp;Xiaomei Fan,&nbsp;Lingxiao Wang,&nbsp;Xiangfei Li,&nbsp;Lin Zhao,&nbsp;Giri Raj Kattel,&nbsp;Xiaoyu Guo,&nbsp;Mengtian Fan","doi":"10.1002/esp.70020","DOIUrl":"https://doi.org/10.1002/esp.70020","url":null,"abstract":"<p>Desertification is defined as land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors. High-spatial-resolution desertification monitoring with long time series and accurate area quantification in the Alxa Desert has yet to be fully elucidated. Here, we exploited Landsat satellite images to develop a method for the monitoring of high-resolution, large-scale desertification dynamics using a Desertification Difference Index (DDI) model based on albedo and Topsoil Grain Size Index (TGSI). On this basis, we examined the spatial–temporal changes in the extent of desertified land and ascertained the impact of various factors (temperature, precipitation, total livestock) on the desertification process. We made a detailed classification of desertification (five types) and found that non-desertification accounted for the smallest proportion of the entire study region (annual mean 2.00 × 10⁴ km², 7.8%), while severe desertification contributed the largest proportion (annual mean 7.88 × 10⁴ km², 30.9%). Over the past 20 years, there has been a substantial reduction in extremely severe (−251 km²/yr) and moderate (−230 km²/yr) desertification areas, demonstrating the effectiveness of desert management. Regionally, considerable attention should be paid to the eastern Tengger Desert in terms of desert control; temporally, special attention should be paid to summer. High temperatures can exacerbate extremely severe, and severe desertification, contrary to the effect of increasing precipitation. Dynamic changes in desertification will become more complex under predicted climate change patterns, indicating that desertification prevention should be prioritized over control.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights into temporal changes in debris flow susceptibility following fire in the Southwest USA from monitoring and repeat estimates of soil hydraulic and physical properties","authors":"Joseph R. Martinez,&nbsp;Luke A. McGuire,&nbsp;Ann M. Youberg","doi":"10.1002/esp.70015","DOIUrl":"https://doi.org/10.1002/esp.70015","url":null,"abstract":"<p>Wildfire influences geomorphic process rates, increasing the potential for runoff-generated debris flows in steep watersheds. Runoff-generated postfire debris flows (PFDFs) often initiate when overland flow rapidly mobilizes sediment from steep hillslopes and channels. Fire effects on soil hydraulic properties, including their magnitude and temporal persistence, can therefore play an influential role in determining the degree to which fire increases debris-flow potential and the time period for heightened debris-flow hazards following fire. There is a paucity of measurements that quantify the timing of changes in soil hydraulic properties throughout the first 1–2 years after fire. Here, we monitored rainfall and debris-flow activity in two watersheds burned by the 2022 Contreras Fire in Arizona, USA, over the first 1.5 years following fire. We quantified changes in soil hydraulic properties during 11 site visits using in-situ measurements with a tension infiltrometer to provide insight into the temporal persistence of heightened debris-flow hazards. Specifically, we estimated field-saturated hydraulic conductivity (<i>K</i>_<i>fs</i>), wetting front potential (<i>h</i>_<i>f</i>) and sorptivity (<i>S</i>). We further tracked changes in soil water repellency, ground cover and soil physical and chemical properties, including bulk density, carbon and organic matter content to help explain temporal trends in soil hydraulic properties. Seasonal variations in <i>K</i>_<i>fs</i>, <i>h</i>_<i>f</i> and <i>S</i> were substantial, leading to non-monotonic relationships between these properties and time since fire. Rainfall-runoff modelling demonstrates that the magnitude of these seasonal changes are sufficient to influence runoff ratios and suggest postfire debris-flow susceptibility could change over timescales as short as several months. A comparison of <i>K</i>_<i>fs</i>, <i>h</i>_<i>f</i> and <i>S</i> at similar times during the first and second postfire years indicates that <i>K</i>_<i>fs</i> <i>h</i>_<i>f</i> and <i>S</i> decreased immediately following the fire. We observed two debris flows, which occurred during the first three months after the fire. The relatively short time associated with notable fire effects on soil hydraulic properties, combined with substantial increases in ground cover during the first postfire year, help explain observations that PFDFs primarily initiate in the first rainy season following fire in the Southwest USA.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143389186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bed material facies mapping at braided river scale and evidence for trends in fine sediment","authors":"Justin M. Rogers,&nbsp;James Brasington,&nbsp;Jo Hoyle","doi":"10.1002/esp.70012","DOIUrl":"https://doi.org/10.1002/esp.70012","url":null,"abstract":"<p>Characterizing the spatial distribution and dynamic nature of bed facies in gravel-bed braided rivers is challenging but necessary to understand fluvial and ecological processes. Topographic point cloud and image datasets are increasingly used in fluvial geomorphology to compare riverscapes over time and classify substrate facies. However, repeatable and efficient methods that operate at large spatial scales and also resolve bimodal or fine sediments remain underdeveloped. This study collected high-resolution lidar and optical imagery over a 56-km reach of the Rangitata River, New Zealand, generating a variety of multiscale lidar-derived, optical and local morphological predictors. Ensemble machine learning methods were used to classify facies at a 1 m resolution, and a sensitivity analysis incorporating downscaled and reduced-fidelity datasets was conducted to understand the importance of data acquisition strategies. We report the predictor importance by class, finding that the key predictors for fine sediment were colour and colour complexity, while lidar predictors including reflectance were key in differentiating shallow water. The classification method was found to be robust with decreasing lidar point density but the performance was degraded if either RGB or lidar datasets were removed entirely.</p><p>The sole use of spatially local predictors allowed an analysis of trends in fine sediment facies in a large braided river subject to hydrologic pressures. The quantity and proportion of exposed fine sediment increased downstream, indicating a decrease in transport capacity associated with river widening. This new lidar – machine learning – substrate processing pathway offers a synoptic view of river form and composition that can be used to parameterize numerical models and provide distributed insights into sediment transport and sorting processes. The approach is easy to customize and can readily adapted to predict different surface classes, providing a robust basis for change detection in natural scenes.</p>","PeriodicalId":11408,"journal":{"name":"Earth Surface Processes and Landforms","volume":"50 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/esp.70012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143389249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}