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Spatio-temporal assessment of the evolution and morphodynamics of the Brahmaputra River (BR) can contribute significantly in mitigating challenges offered by rapid urbanisation and climate change. The present remote sensing and geographic information system (RS and GIS) based analysis of the BR revealed an increased Braiding Intensity (BI) from 1976 to 2000, which declined in 2010, and re-emerged in 2020. The average maximum width of the river has generally widened over time and sandbar distribution has exhibited fluctuations. The overall active channel area increased by 1.5 times, and the sandbar area expanded by 1.2 times between 1976 and 2020. The interplay between braiding intensity and width reveals a positive relationship. The sandbar-water ratio reveals a significant prevalence of sandbars in the Brahmaputra River. Furthermore, the study highlights changes in the Bar Development Index (BDI), showing a significant increase in micro-bars and meso-bars but a decrease in macro-bars. With the approach of change detection, key factors observed within the river driving the changes are erosion, channel bifurcations, sandbar formation due to sediment deposition, and sandbar loss due to shifts in channel course. These characteristics are potentially influenced by high water and sediment influx, climate change, and anthropological activities. [ABSTRACT FROM AUTHOR]

Recreational activities such as jet boating have the potential to disturb native birds that rely on braided river habitats. To examine whether jet boating affects levels of glucocorticoid hormones, which can increase in animals under stress, we compared concentrations of corticosterone in the faeces of nesting black-backed gulls (Larus dominicanus) between days with differing levels of jet boat activity and to a nearby braided river site with no jet boating. The corticosterone titers of gull faeces sampled on the weekends (when jet boating activity was high) were almost twice that collected in the same area during the week (when jet boating activity was low). Corticosterone titers were also lower in the site without jet boating. Corticosterone levels were not significantly related to whether faeces were sampled in the centre or margin of the colony, nor did they vary significantly with number of birds in the colony. It is not known if increased concentrations of corticosterone have any negative effects on the survival or reproductive success of black-backed gulls, but our results suggest that the disturbance created by jet boating has the potential to alter hormone levels in this and perhaps other species that occur in braided river habitats. [ABSTRACT FROM AUTHOR]

The Permian (Changhsingian) Umm Irna Formation (Jordan) yields important plant fossils that have influenced our understanding of the early evolution of plants that later dominated the vegetation of the Mesozoic. The formation was deposited in a fluvial regime characterised by the co-occurrence of stacked small-scale braided channels and of larger, higher-sinuosity channels with deposition on point bars, all intercalated into a heterogeneous background sedimentation of finer-grained floodplain deposits, including stacked crevasse-splay deposits, interspersed abandoned-channel and oxbow-lake fills, and lenses of peaty back-swamp deposits. Here, we document the remarkable compositional variability expressed in 124 palynomorph assemblages that were recovered from different argillaceous deposits in the Umm Irna Formation within a ∼2 km2 outcrop area around a major meandering channel. Our results reveal lateral and vertical variation within individual argillaceous units, as well as lateral variation between different argillaceous units in the same sedimentary complex at similar stratigraphic levels. When combined with plant macrofossil data, the results show that variability in the palynological content may be influenced mainly by two factors. The first is connectedness to the major channel; the drainage system carried a mixture of palynomorphs from across the floodplain but also from a large hinterland of tributaries draining higher parts of the floodplain and uplands beyond to the south and east. The second is the influence of local vegetation communities on the floodplain which would likely be more marked in less connected parts of the floodplain. These findings have implications for the palynological study of alluvial sequences of the Palaeozoic and Mesozoic, and for understanding the ability to identify mudstone units via palynological fingerprinting. Such individual units are of great importance as baffles to fluid flow in reservoirs that might be used for oil and gas, low-temperature geothermal energy storage, carbon capture and storage, and hydrogen storage in alluvial successions. [ABSTRACT FROM AUTHOR]

The tight sandstone reservoris are important exploration and production target in the Xujiahe Formation in Xinchang area of Western Sichuan. Due to the various lithofacies and diagenetic alteration in distributary channel belt sandstones, the reservoirs exhibit strong heterogeneity. The strong heterogeneity makes the identification of petrologically superior sandbodies a great challenge. In order to better understand reservoir quality, this study constructs a model between diagenetic alterations and reservoir quality within distributary channel belts. 73 plug samples were taken from 17 wells located in the channel belt. An integration of thin sections, X-ray diffraction, carbon and oxygen isotope ratios, cathodoluminescence, and micro-CT were analysed for the genesis and distribution of reservoir quality. The results show that subaqueous distributary channels are formed under various hydrodynamics, resulting in different lithofacies. The thicknesses of channels can be divided into less than 2 m, 2–6 m, and more than 6 m. The diagenetic alteration in lithofacies were identified. Coarse-grained sandstones with low content of rock fragments are relatively weakly compacted with less calcite and chlorite cementation. Fine-grained sandstones with high content of rock fragments are strongly compacted with calcite cementation during early diagenesis. The dissolution pores are related to the soluble mineral content and the distribution of mudstones. The subaqueous distributary channels formed in high-energy, moderate-energy, and low-energy hydrodynamic settings have experienced different diagenetic intensities. Additionally, fractures can effectively improve the reservoir properties. The distribution of good quality reservoirs is controlled by the combined influence of diagenetic heterogeneity and fractures. This would help to promote better understanding of reservoir quality within the subaqueous distributary channel belts in braided-river delta front. [ABSTRACT FROM AUTHOR]

Utilizing well logging data, outcrop profiles, and previous research, this study analyzes the sedimentary and tectonic evolution of the Yan'an Formation in the Ordos Basin, correlating the resulting sedimentary facies with hydrocarbon reservoirs to establish the necessary connections. The study reveals that: (1) Vertically, the sediment grain size shows a pattern of coarser grains at the bottom and top, with finer grains in the middle. Horizontally, the grain size tends to become finer from the northern, western, and southern parts of the basin toward the central-western region. (2) Tectonic movements during the Yan'an period controlled the sedimentary environment. These tectonic activities, through uplift and subsidence, caused the Yan'an Formation to experience four stages of sedimentary environments: braided river, lake, delta, and meandering river. (3) The Yan'an Formation exhibits four types of reservoir sandbody stacking patterns—continuous superposition, intermittent superposition, interbedded sand-mud, and single sandbody types—with continuous and intermittent stacking being the most common. (4) The hydrocarbons in the Yan'an Formation originated from the Chang 7 Member of the Yanchang Formation and migrated into the Yan'an reservoirs. The oil is characterized by its low density, low viscosity, and low pour point, indicating it is a high-maturity, high-quality crude oil. [ABSTRACT FROM AUTHOR]

Navigation channels provide a vital link in the supply chain of inland transport. Excavation of sediment from the river bed and fluvial islands is necessary to make the large braided river navigable for transportation. Present research work investigates the feasibility of dredging operations in the mid-sand bars of the Brahmaputra River (Assam, India) for navigation purposes. Pernicious metal (Cu, Zn, Fe, Mn, Ni, Co, Cr, Pb, Cd) concentrations were assessed at 42 sampling locations, covering a reach length of approx. 600 km (reaches 1 and 2). Vertical samples were obtained from 0 cm, 50 cm, and 100 cm of the mid-sand bar. Various indices were evaluated to quantify the contamination level in the mid-sand bars. Based on the enrichment factor (EF), reach 2 was highly enriched with toxic metal-limiting dredging operation. Conversely, reach 1 was found suitable for dredging operations, owing to the low EF value. Various anthropogenic activities are likely to be the causative factor for the heavy metal enrichment in reach 2, including effluents from pharmaceutical industries, oil refineries, and industrial and domestic runoff. Statistical analysis also endorsed those heavy metals possess similar anthropogenic origins. Overall, the dredging can be feasible for reach 1 and at localized zones for reach 2 across the Brahmaputra River. Further, the study tries to present a suitable mitigation measure to carry out dredging operations and manage contaminated dredged sediment for reach 2. [ABSTRACT FROM AUTHOR]

The slopes of Himalayan piedmont and foothill plain are being modified by the Himalayan origin river systems. In this study, spatiotemporal dynamics of channel planform of braided River Jaldhaka have been estimated using United States Army Map (1956) and landsat satellite images (1980-MSS, 1990-TM, 2000-TM, 2010-ETM+ and 2022-OLI) for the delineation of banklines, channel length, sinuosity index, braiding index, channel widths, identification of partial channel avulsion sites and bankline migration using Digital Shoreline Assessment System (DSAS) toolbar. Linear Regression Rate, Net Bankline Movement and End Point Rate were also calculated. Results revealed that the lower reach is more sinuous (maximum average channel sinuosity 1.65) compared with reach-I (1.29) and II (1.11)). The maximum channel width was in the year 2022 (968.6 m) and minimum average channel width was in 1956 (239.87 m). The maximum BI value (3.55) has been calculated in the sub reach-2 (SR-2, reach-I). Similarly, DSAS output shows maximum average EPR values (6.43 m/year) in lower reach which was most erosion prone bank. Bank facies study showed that non-cohesive bank materials accelerate rapid rate of channel avulsion and bank erosion. The variation of discharge, velocity, presence of vegetation and anthropogenic interventions controls the nature of planform changes of Jaldhaka River. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geomechanics is the property of Journal of Geomechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Submarine channels on the seafloor experience a range of turbidity current‐flood hydrographs. The characteristics of the flood hydrograph influence channel dimensions, the number of channel threads (i.e. braiding intensity) and the depositional properties of sandbars within the channels. However, the morphodynamic response of submarine braided channels to different hydrograph patterns is poorly understood. In this study, six geomorphic experiments are used to test how varied flood hydrographs affect the braiding intensity and sandbar geometry within submarine channels. Three experiments represent the control group with constant density‐current inflow, and three experiments use different time‐varying hydrograph patterns. The experiments show that, as the inflow‐to‐sediment discharge ratio increases, multiple small channels coalesce into a few main channels, causing a decrease in active braiding intensity defined by the channel threads with flow. When the flow returns to the initial low flow rate, active braiding intensity increases again. These observations show that the inflow‐to‐sediment discharge ratio determines the value of active braiding intensity. Additionally, active braiding intensity is directly proportional to dimensionless sediment‐stream power and dimensionless stream power, in agreement with previously established trends for both submarine and fluvial braided channels. In contrast to active braiding intensity changes, the measured sandbar aspect ratio and compactness ratio (i.e. ratio of planform area to perimeter) of submarine braided channels is insensitive to changes in the hydrograph. However, when inflows reach peak discharge, the higher transport capacity erodes pre‐existing deposits, forming noticeable erosional surfaces, and subsequently depositing thicker sandbars during that stage. These observations imply that sandbar planform morphology is largely insensitive to hydrograph, but hydrograph variability induces a greater variability in the resultant stratigraphic packages. The experimental results predict that field‐scale stratigraphy should be dominated by strata deposited during intervals of high flow, but that these strata will also exhibit reduced lateral continuity compared to formation scenarios with constant discharge. [ABSTRACT FROM AUTHOR]

Measurement of river bathymetry has been revolutionized by high‐resolution remote sensing that combines UAV platforms with SfM‐MVS photogrammetry. Mapping inundated and exposed areas simultaneously are possible using either two‐media refraction correction or some form of the Beer–Lambert Law to estimate water depths. If, as in turbid glacially‐fed braided streams, the bed is not visible then traditional survey techniques (e.g. differential GPS systems) are required. As an alternative, here we test whether the spatial distribution of water depths in a shallow braided stream can be modelled from basic planimetric data and used to estimate inundated zone bathymetry. We develop heuristic rules using; (1) distance from the nearest river bank; (2) total inundated width along a line tangential to the local flow direction; (3) local curvature magnitude and direction; and distance from the nearest flow (4) divergence and (5) convergence regions. We parameterize them using a sample of measured water depths in stepwise multiple linear regressions and validate them using independent data. Resulting water depth distribution maps explain between 50% and 60% of the measured water depth spatial variability when compared to independent data. After incorporating modelled water depths into digital elevation models (DEMs) of exposed areas, we show that the developed method is suitable for volumetric change calculations in both dry and inundated areas. [ABSTRACT FROM AUTHOR]

The characteristics of fan sediment in the distributive fluvial system are evaluated based on a thorough analysis of modern silt in the Guertu river distributive fluvial system, as well as data obtained from UAV aerial photography and satellite remote sensing. The Guertu River Distributive Fluvial System (DFS) is classified into three stages, namely "proximal," "middle," and "distal," based on the examination of river morphology, sediment variations, sedimentary attributes, and other relevant aspects throughout different sections of its tributaries, from the source to the mouth. At the upstream section of the downstream fining sequence, the slope is the steepest and the hydrodynamic conditions are intense, resulting in the formation of a predominantly big gravel braided river. The river bed section has a morphology resembling a combination of a "V" and a "U" shape. It is characterized by a narrow and deep configuration, with a relatively short breadth. The sediment primarily consists of medium to large-sized gravel with minimal sand content. The gravel exhibits good roundness and displays a considerable degree of orientation. The primary microfacies present are braided channel and flood plain. The slope of the central area is decreased in comparison to the nearby end, primarily due to the presence of extensive braided rivers. The river bed has a greater width, with minor eolian dunes visible in the river channel. The gravel particles are predominantly fine to medium in size, and there is an increased amount of sand present. The predominant microfacies are braided channels, floodplains, and eolian dunes. At the distal end, the slope is minimal, the landscape is level, the braided river transitions into a meandering river, the sediment consists primarily of sand, and the signs of bioturbation are clearly visible. The primary microfacies consist of braided channels, meandering channels, floodplains, eolian dunes, lakes, and swamps. [ABSTRACT FROM AUTHOR]

As in most chalk river valleys in NW Europe, the sedimentary fill of the Somme valley is mainly composed of fluviogenic alkaline peat. The site of Morcourt exhibits a thick and well‐preserved fluvial sequence (10 m, including 6 m of peat). This sequence provides the framework for reconstructing fluvial and palaeoenvironmental dynamics from the end of the Upper Weichselian Pleniglacial (~20 000 cal. a BP) to the High Middle Ages (~700 cal. a BP). The palaeoenvironmental reconstruction is based on a high‐resolution stratigraphic study of 60 transect cores, 36 radiocarbon dates and sedimentological, geochemical, pollen and plant macrofossil analyses. There are three main phases in the development of the valley floor: (i) after the incision of the abandoned Pleniglacial braided river channels, a first generation of localized peat developed during the Bølling and the Allerød interstadial (<1 m thick); (ii) at the beginning of the Holocene, a peat formation phase began in the deepest parts of the valley and then spread over the valley floor by the end of the Middle Holocene (~4700 cal. a BP), with the limited runoff shifting to a small lateral channel; and (iii) at the transition to the Late Holocene, environmental changes, driven by the intensification of human activities and perhaps accentuated by climatic modifications, caused the incision of the peat system as a result of the formation of a channel. This channel drained the valley, and then mixed a detrital load into the peat. By the Low Middle Ages, the system had been altered to such an extent that the peat was completely covered by organic silty alluvium. The water table was lower, which definitively inhibited peat formation. The Morcourt sedimentary record (thickness and continuity) and the resumption of turfigenesis during the Late Holocene are remarkable in NW Europe, making this site a model of continuous morpho‐fluvial evolution since the Lateglacial. [ABSTRACT FROM AUTHOR]

Understanding the heterogeneity of reservoirs is crucial for enhancing the efficiency of hydrocarbon exploration and development. The primary porosity of samples from modern braided river sands and outcrops of braided river sandstone was calculated using a model previously proposed by the authors. The characteristic parameters (Vx) for calculating primary porosity are closely related to the architectural–elemental configurations (AEC), and the AEC of braided river sand bodies (BRSD) has apparent effects on the distribution of the primary porosity heterogeneities. Analysis of our results has established a simple primary porosity heterogeneity model of BRSD. The center of braided river channel and mid-channel bars have excellent strong primary petrophysical properties with high primary porosity exceeding 38%. The contact areas between the braided river channel and channel bars exhibit relatively low primary porosities of less than 33%. The area between the center and edge of the braided bars and channels displays medium primary porosities. The nonlinear correlation in the Q–Q plot of the primary porosity and present porosity of samples from BRSD in the Ahe Formation is mainly caused by chemical diagenesis. The present porosity heterogeneity of BRSD in the Ahe Formation is less influenced by compaction and cementation, it predominantly arises from the differential of dissolution. Q–Q plots attempt to correlate the geological information from an individual sample with the heterogeneity of present porosity in BRSD. In addition, by utilizing Q–Q plots of the primary and current petrophysical properties of the sand body, the relative extent of heterogeneity modification caused by different diagenetic processes can be assessed. This assessment is crucial for modeling macroscopic models of physical properties during geological history periods. [ABSTRACT FROM AUTHOR]

Effective monitoring of global water resources is increasingly critical due to climate change and population growth. Advancements in remote sensing technology, specifically in spatial, spectral, and temporal resolutions, are revolutionizing water resource monitoring, leading to more frequent and high-quality surface water extent maps using various techniques such as traditional image processing and machine learning algorithms. However, satellite imagery datasets contain trade-offs that result in inconsistencies in performance, such as disparities in measurement principles between optical (e.g., Sentinel-2) and radar (e.g., Sentinel-1) sensors and differences in spatial and spectral resolutions among optical sensors. Therefore, developing accurate and robust surface water mapping solutions requires independent validations from multiple datasets to identify potential biases within the imagery and algorithms. However, high-quality validation datasets are expensive to build, and few contain information on water resources. For this purpose, we introduce a globally sampled, high-spatial-resolution dataset labeled using 3 m PlanetScope imagery. Our surface water extent dataset comprises 100 images, each with a size of 1024×1024 pixels, which were sampled using a stratified random sampling strategy covering all 14 biomes. We highlighted urban and rural regions, lakes, and rivers, including braided rivers and coastal regions. We evaluated two surface water extent mapping methods using our dataset – Dynamic World , based on Sentinel-2, and the NASA IMPACT model , based on Sentinel-1. Dynamic World achieved a mean intersection over union (IoU) of 72.16 % and F1 score of 79.70 %, while the NASA IMPACT model had a mean IoU of 57.61 % and F1 score of 65.79 %. Performance varied substantially across biomes, highlighting the importance of evaluating models on diverse landscapes to assess their generalizability and robustness. Our dataset can be used to analyze satellite products and methods, providing insights into their advantages and drawbacks. Our dataset offers a unique tool for analyzing satellite products, aiding the development of more accurate and robust surface water monitoring solutions. The dataset can be accessed via 10.25739/03nt-4f29. [ABSTRACT FROM AUTHOR]

The Gandak River originates in Nepal and merges with the Ganga River in India. The Gandak River is experiencing significant geomorphological alterations due to climate change and anthropogenic causes. In this study, an attempt has done to examine river bank erosion & accretion, shifting of the river bank, sinuosity, and braiding index of the Gandak River between Sahibganj and the confluence with the Ganga River, covering a length of 92.4 km from 1989 to 2022 (33 years) using remote sensing and geospatial technologies. The delineation of the river bank line for different periods, along with the quantification of erosion and accretion of the river's right and left banks, were analysed using GIS, including the sinuosity and braiding patterns. The overall sinuosity value ranged from 1.16 to 1.01 and did not follow any specific pattern in significant reaches. The sinuosity value was almost constant over the most d/s reach of 30.74 km. The braiding index of the River was found to be the maximum between Ismailpur and Baijalpur and the minimum value between Munja and Chakia in 2015 and 1995 respectively. This study revealed that the river is shifting to the right, and bank protection measures were needed. Finally, the proposed investigation revealed the braiding phenomenon, river shifting in the transverse direction, and shifting of the meander bend was primarily responsible for the erosion and accretion of the river banks. This study will benefit local government agencies, concerned authorities, and people residing along the banks of the Gandak River by providing insights into the river's migration patterns. Further, this knowledge aids in better planning of riverbank protection measures and developing a navigation system. [ABSTRACT FROM AUTHOR]

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Sandbars are an integral part of the alluvial river's geophysical system due to these rivers' wide sediment availability and varied transport capacity. The sandbars' evolution and translation considerably influence the stability of the riverbank. However, while designing the riverbank protection structures (RBPS), the impact of such sandbars is often overlooked, as the evolution of such bars is quite uncertain in terms of location, amplitude, and translation. This study evaluates the localized impact of sandbars on bank protection structures in two types of alluvial rivers: meandering (Ganges) and braided (Brahmaputra-Jamuna), utilizing time series satellite images, hydraulic characteristics, and numerical modeling. We found that sandbar development initiates width adjustment in both meandering and braided rivers when the ratio of width to depth surpasses 90. In the case of meandering rivers, riverbank erosion mostly occurs as a result of the presence of alternate bars or point bars. Sandbars in a meandering river (Ganges) can lead to an approximate 18% increase in flow depth. The depth-averaged velocity is anticipated to rise by approximately 29%, and the tractive force may increase by a factor of 1.6. On the other hand, the braided river (the Brahmaputra-Jamuna) underwent significant bank erosion due to the presence of both free unit and hybrid types of bars. In such rivers, the depth of the flow may experience a notable increase of 18%, while the depth-averaged velocity undergoes an approximate increase of 50%, and the tractive force has the potential to grow by a factor of 5.3. Consequently, we recommend allowing the natural evolution of sandbars while preserving the riverbank (where needed only) through RBPS, considering these additional loads. [ABSTRACT FROM AUTHOR]

Copyright of CT Theory & Applications is the property of Editorial Department of CT Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Riverbank and in-stream protection are crucial in numerous river stretches, where erosion of banks and bed material instigates river course alterations, consequently leading to land and property damage. In large Indian braided rivers like Brahmaputra, implementing tetrahedron frames commonly referred to as 'porcupines' has emerged as a cost-effective strategy for river training, yielding commendable outcomes in near bank sedimentation. Using flexible river training structures, such as porcupine, presents an appealing option for managing braided river channel networks in areas where permanent control structures like groynes or dams prove excessively costly or potentially ineffective, particularly in systems exhibiting highly dynamic flow regimes and morphology. This work aims to develop a hydrodynamic model that integrates the porcupine systems within its framework. The model's effectiveness was assessed through a field test near Nematighat, Brahmaputra River, in collaboration with Assam's Water Resources Department. The mathematical modelling provided some valuable insights regarding the flow characteristics surrounding the porcupine structure, shedding light on its hydrodynamic behaviour. [ABSTRACT FROM AUTHOR]

The lithofacies and pedogenic features in the Late Oligocene–Early Pleistocene formations provide evidence of changing paleoclimate in the northeastern Sahara region. The strata of the Katkut Formation and the lower Member of the Madamud Formation consist predominantly of coarse and fine-grained siliciclastic lithofacies deposited by braided and sinuous streams that formed under the influence of humid paleoclimate during the Late Oligocene–Late Miocene time. Paleosol horizons with mature calcretes in the overlying upper member of the Madamud Formation suggest increasing aridity by the end of Late Miocene through Pliocene time. This trend of aridification continued during the Early Pleistocene lacustrine deposition of Issawia and Armant formations, as indicated by the predominance of palustrine carbonates displaying different pedogenic features. The climate change may have resulted from the southward movement of Asian monsoons and the uplifts of the Red Sea Mountain chains, as the African continent drifted northeastward. This paleoclimate transition generated variations in basin sedimentation rates that were controlled by base level and tectonics. [ABSTRACT FROM AUTHOR]

Accurate monitoring of river discharge variations is essential for managing floods and droughts and understanding the response of global river systems to climate change. Remote sensing of discharge (RSQ) offers a timely and efficient alternative for widespread monitoring, particularly in ungauged areas. Current methods often struggle with accuracy, especially when estimating the width of narrow rivers from medium‐resolution images. We first observe that, although estimating the width variation of narrow rivers can be challenging from medium‐resolution satellite imagery, river discharge still correlates with river surface color or reflectance. However, existing methods can only correlate river surface reflectance with discharge in gauged rivers. Here, we introduce a novel method employing an advanced Transformer architecture to map river discharge variations directly from time‐series reflectance imagery. Our model, trained on quality‐checked data from 2,036 discharge gauges, outperforms existing methods in discharge estimation accuracy and is less affected by the need for precise river width estimation. The proposed model yields positive Kling‐Gupta Efficiency (KGE) in 68.6% of ungauged rivers, a substantial improvement over the BAM and geoBAM methods, which show positive KGEs in only 28.4% and 33.1% of rivers, respectively. Notably, this performance is achieved despite two‐thirds of the rivers being less than 100 m wide, a range where traditional RSQ methods typically struggle, and the RSQ performance does not show degradation for braided rivers. Our approach suggests a significant shift toward more efficient, extensive, and adaptable space‐based river discharge monitoring. Plain Language Summary: Monitoring river discharge is crucial for managing water‐related disasters like floods and droughts and for understanding how rivers respond to climate change. Traditional methods that use remote sensing to monitor discharge (RSQ) often face challenges, especially with accurately measuring the width of narrow rivers using satellite images. However, we've noticed that the color or reflectance of a river's surface, which can be seen from space, still tells us something about the river's discharge, even if the width is hard to measure accurately. Our study introduces a new method using a Transformer architecture that learns to estimate river discharge directly from how the river looks in time‐series satellite images. We trained our model using data from 2,036 river gauges and found that it performs better than existing methods. It is particularly effective in areas where we don't have direct river discharge measurements, achieving good results in 68.6% of these cases‐a big improvement over the 28.4% and 33.1% success rates of previous methods. This is impressive because two‐thirds of the rivers we studied are less than 100 m wide, where older methods usually fail. Key Points: Deep learning model maps river discharge from satellites in ungauged rivers, improving accuracy for rivers over 30 m wideThe model uses Transformer architecture, correlating river surface reflectance data with discharge when width changes are minimalValidated with positive Kling‐Gupta Efficiency in 68.6% of ungauged rivers, median width 67 m, significantly better than existing Mass Conserved Flow Law Inversion (McFLI) methods [ABSTRACT FROM AUTHOR]

With rising air temperature and precipitation, water and sediment fluxes in the Source Region of the Yangtze River (SRYR) have increased since 2000s. Nonetheless, the response of braided river morphology to climate‐driven water and sediment flux change is still unknown. Water bodies of 9 large braided rivers from 1990 to 2020 were extracted based on Google Earth Engine platform, and impacts of climate change on morphological indices and morphodynamic processes were quantified. A new segmentation method is presented to more precisely extract braided river water body when the branch width is less than an image pixel size. The warming and wetting trend led to vegetation cover increase. With the increase of water flux, the water area of each braided reach has increased in both flood and non‐flood season. The 3–5 years mean annual erosion and accretion intensity (newly proposed in this study) of the channel shows three different trends of increasing, weakening, and unchanged over time. These three trends can be classified into three patterns in response to climate‐change driven water and sediment flux change in the SRYR as follows: sediment increase constrained pattern (weakening or unchanged), sediment increase dominated pattern (increasing), and water increase dominated pattern (increasing or unchanged). In summary, the braided rivers in the SRYR showing consistent increasing of water area, general expansion of active channel, and increasing of erosion and accretion intensity for some of the rivers, with the climate‐driven increasing water and sediment flux. Key Points: A new method of braided water body extraction improves accuracy of recognitionThe warming and wetting trend has led to the more durative inundation of braided rivers since 2000s and consistent expansion of the channelMean annual channel erosion and accretion intensity differently responds to the increase of water and sediment flux in nine braided rivers [ABSTRACT FROM AUTHOR]

Enhanced understanding of flow structure in braided rivers is essential for river regulation, flood control, and infrastructure safety across the river. It has been revealed that the basic morphological element of braided rivers is confluence-bifurcation units. However, flow structure in these units has so far remained poorly understood with previous studies having focused mainly on single confluences/bifurcations. Here, the flow structure in a laboratory-scale confluence-bifurcation unit is numerically investigated based on the FLOW-3DR® software platform. Two discharges are considered, with the central bars submerged or exposed respectively when the discharge is high or low. The results show that flow convergence and divergence in the confluence-bifurcation unit are relatively weak when the central bars are submerged. Based on comparisons with a single confluence/bifurcation, it is found that the effects of the upstream central bar on the flow structure in the confluence-bifurcation unit reign over those of the downstream central bar. Concurrently, the high-velocity zone in the confluence-bifurcation unit is less concentrated than that in a single confluence while being more concentrated than that observed in a single bifurcation. The present work unravels the flow structure in a confluence-bifurcation unit and provides a unique basis for further investigating morphodynamics in braided rivers. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Indigenous peoples of Aotearoa New Zealand, Māori, are often excluded and underserved by hearing health services that often neglect their cultural values and needs. In response to this, we aimed to advance the delivery of culturally appropriate services with Māori clients through the validation of a te reo Māori hearing screening test. A He Awa Whiria: Braided rivers framework was applied to weave Māori knowledge and cultural values into this audiological research and to support the collaboration of Māori and non-Māori researchers through a Kaupapa Māori approach stream. While the validation of the screening test was interrupted due to COVID-19, we discuss in detail the approach stream used in this study. Together the approach and validation streams form the foundation of an ongoing research initiative aimed at addressing Western biomedical approach limitations, expanding the hearing health sector's knowledge base to deliver culturally responsive care, and in a small way contributing to the revitalisation of te reo Māori.Glossary of Māori words: Ahitereiria ki te Hauāuru: Western Australia; atua: ancestor with continuing influence; Aotearoa: North Island of New Zealand - now used as the Māori word for New Zealand; hapū: sub-tribal, clans, wider whānau descent or political units; hongi: traditional Māori greeting; He Awa Whiria: braided rivers approach; hui: meeting; ia: Te reo Māori pronoun for everyone; iwi: tribe; kai: food; Kai Tahu/Ngai Tahu: tribal group of the South Island; kanohi kitea: the seen face; kanohi ki te kanohi: face-to-face; karakia: incantation, chant, thought, or prayer; kaumātua: Māori elder/s; kaupapa: topic, policy, matter of discussion; Kaupapa Māori: a philosophical approach using Māori knowledge and values; kete: woven basket/s; Kohanga Reo: Māori language preschool; kōrero: narratives and prose; koringo-tangi-roa: the wooden flute or trumpet of Ngongo; kūmara: wweet potato; Kura Kaupapa: Māori language immersion schools; kupu: word, vocabulary; manaakitanga: the process of showing respect, generosity and care for others; Māori: Indigenous people of Aotearoa New Zealand; marae: a significant Māori community complex of buildings; mātauranga Māori: Indigenous Māori knowledge; Ngā Rauru: an iwi of Taranaki; Ngāpuhi: a tribal group situated in the top of the North Island; Ngāti Hau: people of the Whanganui River; Ngāti Porou: a tribal group of the East Coast of the North Island; Ngāti Whātua: tribal group between the Hokianga Harbour and Tāmaki; Ōtautahi: traditional name known now as Christchurch; Pākehā: New Zealander with European descent, non-Māori; Papatūānuku: Earth mother; pihoi: inattentively deaf; pūwharawhara: deaf; Rakinui/Ranginui: Sky father; Rehua: a deaf atua associated with kindness, a child of Pāpātuanuku and Rakinui; tāhorehore: deaf as if the ears were cropped; Takaroa/Tangaroa: an atua of the sea; Taki-ao-terangi: daughter of Rehua; Tāmaki: Auckland; Tāne-tūturi: a deaf child of Ranginui and Papatūānuku; Tangata Tiriti: people of Te Tiriti, referring to all non-Māori citizens and residents of Aotearoa; tangata whenua: people of the land, Indigenous peoples, local people, hosts; taonga: treasure of social or cultural value; tapu: sacred, spiritual restriction containing a strong imposition of rules and prohibitions; taringa kōhatu: deaf, stubborn; taringa muhu kai: ear listening for food - a person whose only concern is when food is served; taringa puta iti: little ear orifice, inattentive; taringa turi: deaf; teina: young, less skilled learner; te Ao Māori: the Māori world; te reo Māori (te reo): the Māori language, Indigenous language of Aotearoa; Te Tiriti o Waitangi: Signed in 1840 this is the Māori language version of an agreement between two internationally recognised sovereign nations, Māori, as tāngata whenua, and the British Crown; Te Waipounamu: the South Island of Aotearoa New Zealand; Te Whakamātautau Whakarongo o Aotearoa: Te Reo Māori Digit Triplet Test, TRMDTT; tikanga Māori: Māori customs, procedures, protocols, practices, system of values, the Māori way; tīpuna: ancestors; tohunga: priest, practitioner, expert; tuakana: mentors; turi: deaf; turikere: deafened; waiata: songs and chants; wairuatanga: spiritual well-being; Waitaha: traditional name for region known as Canterbury; wānanga: to meet and discuss, Māori learning, educational forum; whakamā: shame, embarrassment, guilt; whakapapa: To place in layers, to recite genealogies, lineage; whakarongo: an intransitive verb that can mean to listen but may also be used to ready the senses such as to smell, touch or feel; whakataukī: proverb, significant saying; whakawhanaungatanga: an indigenous process of creating relational connection; whānau: immediate and extended family and friends. [ABSTRACT FROM AUTHOR]

The White Hills Gravel is the coarsest fluvial gravel within Victoria, southeastern Australia, and outcrops discontinuously across a substantial part (>35 000 km2) of this region. It overlies a major regional unconformity representing >300 Ma, and is dominated by conglomerate (61% of beds), with less abundant sandy lithofacies (36% of beds) and rare mudstones (3% of beds). The sedimentary characteristics of the basal conglomerates (e.g. thick bedding, common boulders, very poor sorting and in places chaotic appearance) indicate deposition by significant paleofloods, including debris floods, within braided streams that had similar flow directions to the modern drainage. Paleohydraulic calculations estimate that the paleofloods had discharges exceeding >7200 m3 s−1, over 25 times the largest recorded floods in the same valleys. These paleofloods were probably caused by exceptionally severe storm systems, consisting of many individual thunderstorms. Deposition of the White Hills Gravel has previously been attributed to the mid-Cretaceous uplift that affected southeastern Australia, but the maximum possible age of the formation (early Paleocene) is too young for this to be a viable explanation. Instead, the White Hills Gravel may have been deposited during a period of increased precipitation at the Paleocene–Eocene Thermal Maximum (ca 56 Ma), when an intensification of the hydrological system generated significant sediment responses within fluvial systems around the world. Modelling indicates that this climatic event had a substantial impact in Victoria, where increases in mean annual precipitation (50–60%) and the most extreme rainfall rates achieved by the strongest storms (60–70%) were some of the largest globally, and frequent and intense Atmospheric Rivers were an important part of the hydrological system. These factors, together with a period of disturbed vegetation cover, resulted in major paleofloods that could have deposited the coarse-grained conglomerates of the White Hills Gravel. KEY POINTS: The White Hills Gravel in central Victoria is dominated by conglomerate (∼61% of beds), with lesser sandstone (∼36% of beds) and rare mudstone (∼3% of beds). In valleys across the central Victorian Highlands, White Hills Gravel outcrops are characteristically elevated above the Calivil Formation, and in the Campaspe and Loddon valleys, the long profiles of both formations cross over downstream. There is no evidence of a tectonic origin for the formation; instead, the White Hills Gravel was most likely deposited in response to a sharp rise in precipitation. The very-coarse-grained base of the formation was deposited by major thunderstorm-generated paleofloods with discharges up to and exceeding 7200 m3 s−1 in small catchments. The White Hills Gravel may denote a significant fluvial response to climate modification across the Paleocene–Eocene Thermal Maximum. [ABSTRACT FROM AUTHOR]

Strong aggradational tendencies during the late Pleni-Weichselian have been noted in river valleys in central Europe. Thick series of mineral deposits were laid down, but also organic or mineral-organic horizons were formed under favourable conditions. The study area is located in the central section of the valley of the River Warta within an extraglacial area of the last glaciation. At the Warenka site alluvia, that attain thicknesses of 16 m, were analysed. Lithofacies analysis, OSL dating of mineral sediments and radiocarbon dating of organic and mineral-organic strata were performed. Organic and mineral-organic deposits were also subjected to pollen and Cladocera analyses. Together this set of analyses was used to determine fluvial processes and environmental conditions during the late Pleni-Weichselian. The results obtained allow the conclusion that these levels were deposited in the sedimentary environment of a low-energy, sand-bed braided river, which operated in the period from approximately 30 to 24 cal kBP – the late Pleni-Weichselian. During this time, there were periods when shallow water bodies were formed on the valley bottom, where deposition of organic material was possible. The presence of this type of sediment made it possible to reconstruct the vegetation cover; this had the character of a steppe-tundra, periodically shrubby steppe-tundra. Short-lived reservoirs were characterised by shallow-water settings with weakly developed vegetation and temporary influence of floodwaters as indicated by changes in cladoceran assemblages. Pollen spectra, low concentration of cladocerans, as well as the presence of the cold-tolerant Cladocera taxa are indicative of cold climatic conditions. [ABSTRACT FROM AUTHOR]

The Paleogene sandstone reservoir of Huizhou Sag is an important target for deep exploration in the Pearl River Mouth Basin, South China Sea. Because of the intense volcanic activity, it had a significant impact on the development of reservoirs, making it hard to predict. The diagenetic process of volcanogenic sediment and their influence of the reservoir have been studied by petrographic analysis, X-ray diffraction and scanning electron microscopy (SEM). Four types of volcanogenic sediment were identified: volcanic dust (<0.05 mm), volcanic rock fragments, crystal fragments (quartz and feldspar) and vitric fragments. The strong tectonic and volcanic activity of the Wenchang Formation resulted in a high content of volcanic materials, which led to significant reservoir compaction. The main sedimentary facies types are fan delta facies and lacustrine facies; the thick lacustrine mudstone can be used as high-quality source rock. After the source rock of the Wenchang Formation matured and discharged acids, feldspar and rock fragments dissolved to form dissolution pores, which effectively increases the porosity of the reservoir, but the argillaceous matrix and clay minerals produced by the volcanic dust alteration would reduce the permeability of the reservoir. With the weaker tectonic activity of the Enping Formation, the sedimentary facies changed into braided river delta, resulting in the greater componential maturity of the reservoir. Due to the relatively small impact of acidic fluids on the reservoir, the pore types of the reservoir are mainly primary pores with good physical properties. [ABSTRACT FROM AUTHOR]

Much attention has been given to how involvement in research can improve teachers’ practices and student outcomes. Less has been said about how teaching in schools can improve researchers’ practices and the quality of their research. In this article, I discuss advantages encountered conducting research in schools while also teaching part time. This ‘braided river approach’ of teaching at one school while researching at other, similar schools, allowed for a helpful balance between insider-ness and outsider-ness while collecting and analysing data. I found that part time teaching assisted my research by improving access and rapport with participants, by providing an empathetic, nuanced lens for analysis, and by keeping my research focused on relevant, impactful lines of inquiry. Ideally, qualified education researchers should be allowed time to teach in schools, with potential benefits for researchers, teachers, and children. [ABSTRACT FROM AUTHOR]

The Paleogene-Neogene strata in the Western Depression of the Qaidam Basin represent a primary focus for oil and gas exploration and development. Influenced by both terrigenous clastic influx and endogenic carbonate deposition, these strata exhibit significant variation in sedimentary systems and reservoir characteristics. This study comprehensively examines the depositional patterns and reservoir properties of the Paleogene-Neogene sequence across the inner, middle, and outer belts of the basin, employing core analysis, thin section petrography, and physical property assessment of reservoirs. Key findings include 1) The development of a concentric sedimentary system in the Western Depression during the Paleogene-Neogene period, characterized by increased carbonate mineral content and decreased clastic material from the periphery to the center of the basin. 2) Varied sedimentary facies associations across different zones, with the outer belt dominated by fan delta and braided river delta deposits, and the middle and inner belts characterized by near- shore shallow lacustrine carbonates and algal mat deposits, and offshore semi-to deep-lacustrine fine sediments, respectively. 3) The outer belt exhibits reservoirs with favorable physical properties and connectivity, while the inner and middle belts show high heterogeneity, indicating potential for lithological traps and shale oil exploration. These insights offer scientific guidance for further investigation into the depositional systems of lacustrine basins in the Western Depression of the Qaidam Basin and for identifying promising reservoirs. [ABSTRACT FROM AUTHOR]

The lacustrine coal deposits at Nýřany, Czech Republic, yielded a diversified vertebrate assemblage of the Middle Pennsylvanian (Moscovian) age, represented by the remains of early tetrapods, as well as numerous freshwater ichthyofauna, including xenacanthiform sharks, acanthodians, dipnoans, and ray-finned fishes. However, unlike some other upper Carboniferous localities, the actinopterygian diversity is limited to the three small-bodied species, most of them endemic to Nýřany locality and the equivalent strata elsewhere, indicating that the true taxonomic diversity of the group at the locality may be biased. Here we describe first skeletal remains of large actinopterygian fishes from the site, including a new genus and species, Stambergichthys macrodens gen. et sp. nov., which is represented by a well-preserved mandible with teeth. The micro-computed tomographic techniques revealed in the specimen a presence of a complex neurovascular system innerving the teeth and the jaw, and supplying both with blood vessels. The dentition consists of a single row of massive, homodont, conical teeth, which possess simplexodont plicidentine on their base, the characteristics supporting the predatory ecology of the new species. The isolated skeletal remains of large-bodied actinopterygians expand the knowledge on the diversity of the group in Nýřany, and their occurrence in coal deposits of relatively shallow lake indicates they represent allochthonous, poorly known aquatic vertebrate association, likely originating from the braided river system. These findings underline the importance of less complete skeletal materials occurring in wellknown vertebrate assemblages of the upper Carboniferous coal-bearing localities. [ABSTRACT FROM AUTHOR]

• The coupled 2D mophodynamic model considers effects of sediment concentration and bed deformation in the governing equations. • Unstructured meshes better conform with the irregular geometry of the natural rivers. • Channel adjustments play a significant role in sediment transport of alluvial rivers during a flood event. It is difficult to predict the detailed morphodynamic processes induced by heavily sediment-laden floods in alluvial rives, due to the complexity in topography and the significant channel evolution rates, especially in a braided reach of the Lower Yellow River (LYR). A two-dimensional morphodynamic model using a coupled solution approach was firstly developed, with the effects of sediment concentration and bed deformation being directly considered in the hydrodynamic governing equations. The finite volume method with the HLL-MUSCL scheme was adopted in the numerical solution, which can obtain second-order accuracy in space and time. In addition, unstructured meshes were used to accommodate the irregular boundaries. The proposed model was validated using measurements in the braided reach of the LYR during the flood events of 2020 and 2004, with general agreement obtained between the calculated and measured hydrographs of flow and sediment concentration. The highest accuracy was achieved in the simulation of discharge, with a Nash-Sutcliffe efficiency coefficient (NSE) of 0.92. The simulation accuracy in sediment concentration was improved by the coupled approach, with the relative error of the calculated peak value decreasing from 17 % to 9 %. In addition, transport characteristics of graded suspended sediments were well simulated, with the fine fraction being transported downstream and the medium fraction depositing in the study reach. Influences of channel adjustments on the sediment transport processes were investigated during a flood event. The results demonstrated that the incised channel in 2020 was characterized by a larger water depth and smaller velocity, as compared with the shallow channel in 2004. Consequently, the peak discharge decreased and the flood propagation time was extended under the 2020 topography, associated with the lower sediment discharge at the outlet due to the reduced sediment transport capacity. [ABSTRACT FROM AUTHOR]

Storm deposits or tempestites are event sequences formed by storms, requiring at least a water temperature of 26.5°C. While inland lakes are unlikely to form storm deposits because of their limited width and water temperature. The Upper Triassic Xujiahe Formation in the Sichuan Basin is a set of coal-bearing, clastic sequences with dominant sedimentary facies varying from braided river delta to lacustrine settings, with storm deposits widely reported. In the Zilanba of Guanyuan area, in situ tree trunks on a palaeosol surface in Member V of the Xujiahe Formation provide new evidence of a storm event. Six fallen-down directions of nine in situ tree trunks were predominant in the NW direction, contrary to the palaeocurrent direction of the underlying strata, suggesting that the southeasterlies prevailed during the end-Triassic in the northern Sichuan Basin. Massive mud clasts were frequently recorded in sandstones of the Xujiahe Formation, as well as in the Xindianzi section. These mud clasts showed a rip-up or a plastic deformation with upside-down V-shapes, were capped on an erosional surface, showed no transport traces and were therefore interpreted as a storm lag deposit. The megamonsoonal climate prevailed during the Late Triassic, although the megamonsoons themselves could not generate a storm deposition in the Xujiahe Formation due to its low maximum surface wind speed. The driving mechanism for generating storm deposits in the Xujiahe Formation is suggested to be tropical cyclones over the Tethys Ocean moving eastward, further landfalling on the western margin of the Sichuan Basin. Statistics of storm events in the circum-Tethys region show a widespread storm surge in low latitudes during the end-Triassic. The storm deposits at the top of the Xujiahe Formation represent a sedimentary response to the end-Triassic hyperthermal event. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Channel migration, furcation, and vegetation succession are characteristic processes of braided gravel rivers in Alpine regions. These are associated with a frequent turnover of large parts of the active floodplain. However, more than one century of river regulation has reduced or destroyed most of these ecosystem dynamics. More recently, there have been attempts to restore at least some sections of degraded rivers, while there is little monitoring of the biogeomorphological dynamics of such rivers. Thus, we did a four‐year analysis of four representative sections of the upper River Isar in Southern Germany differing in their degree of naturalness. Dynamics of channels, gravel bars, and vegetation were recorded by drone images, and braiding and gravel indices were calculated. When comparing the near‐natural, semi‐natural, degraded or restored sections, there was a gradient of decreasing channel migration, gravel bank expansion, and bank erosion due to a reduced turnover frequency. Biogeomorphological variation among years correlated with log peak discharge within the four sections. In addition, the cover and height growth of vegetation increased with river degradation, and channel migration was positively related to the braiding index. The total turnover of the active river corridor and of the vegetation were positively correlated with log peak discharge within the four sections. The floodplain dynamics of the restored section were improved compared to the degraded section but did not reach a near‐natural state. Thus, Alpine river sections with contrasting degrees of naturalness differ in terms of habitat turnover and vegetation succession, and these characteristics can only partially be restored by local measures. [ABSTRACT FROM AUTHOR]

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This work studies the multiple sources of impacts and disturbances in the Laja River (Central Chile) and evaluates the changes in water and sediment flows and planimetric geomorphic changes. The disturbances sources correspond to hydroelectric plants, water withdrawals for irrigation and the sustained decrease trend in rainfall in the basin. The changes in the plan‐view shape of the river reach were quantified using remote sensing techniques, through a supervised classification of Landsat 5 TM and 8 OLI satellite images, identified Water (W), Islands and Riverine Vegetation (IRV) and Bars and Banks Without Vegetation (BBWV), obtained a Kappa index>0,83 for a period of 15 years (2006–2021). Compared with historical records, the period of analysis shows a decrease in annual rainfall by 17.5%. In addition, water withdrawals for irrigation have contributed to a 64% decrease in monthly stream discharge during the dry season. As a consequence of the decrease in annual rainfall and water withdrawals for irrigation, the sediment transport capacity has also decreased by 10.5%. The changes in morphological driving variables (stream flows and sediment transport regimes) have manifested themselves in morphological changes, where it was possible to establish that a change in the channel form occurred in the last 15 years, going from a river with a single channel to a braided one. An important vegetation establishment has accompanied this morphological change on both riverbanks and the central bars. The colonizing vegetation corresponds to fast‐growing non‐native species (Salix spp., Populus spp. and Alnus spp). A stabilization of the channel form is expected, consolidating itself as a braided section with alternating vegetated bars. [ABSTRACT FROM AUTHOR]

Source‐to‐sink transfer of sediment and organic carbon (OC) is regulated by river mobility. Quantifying trends in river mobility is, however, challenging due to diverse planform morphologies (e.g., meandering, braided) and measurement methods. Here, we utilize a remote‐sensing method applicable to all planform morphologies to quantify the mobility timescales of 80 rivers worldwide. Results show that, across the continuum from meandering to braided rivers, there is a systematic reduction in the timescales of channel mobility and—to a lesser extent—floodplain reworking. This leads to a decrease in the efficiency with which braided rivers rework old floodplain material compared to their meandering counterparts. Reduced floodplain reworking efficiency of braided rivers leads to smaller channel‐belt areas relative to their size. Results suggest that river‐mobility timescales derived from remote sensing can aid in the characterization of sediment and OC storage and transit times at a global scale. Plain Language Summary: Rivers transport sediment and organic carbon (OC) from the mountains to the sea, and river movement affects sediment and OC transit times in landscapes. Understanding the controls on timescales of river movement is critical for assessing how fluvial processes influence the terrestrial carbon cycle. While previous work has quantified different river planform shapes on the Earth's surface (e.g., meandering, wandering, and braided), little is known about how the pace and nature of river movement is different between river planform shapes. This is because we lack methods to measure and compare river movement across different river planform shapes. Here, we leverage a tool to quantify river movement from time series of satellite imagery that is equally applicable to all river planform shapes. We apply this method to calculate the timescales of river movement of 80 rivers worldwide for the last 37 years. We show that (a) braided rivers migrate faster than meandering rivers, and (b) braided rivers move over a smaller area relative to their size. Comparing results with geochemical observations from the Río Bermejo—a well‐studied river for sediment‐OC cycling—we show that our mobility framework may provide a new way to assess sediment and OC storage timescales in floodplains. Key Points: We quantify timescales of floodplain reworking and channel‐overlap decay from satellite imagery of 80 rivers worldwideFrom meandering to braided planform morphology, there is a reduction in the overlap timescale and the reworking timescaleMobility timescales provide a means for remotely quantifying terrestrial‐sediment and organic‐carbon storage and transit [ABSTRACT FROM AUTHOR]

On Kerrera island, poorly dated braided stream conglomerates and sandstones are interbedded with finer lake siltstones and shales, with land plants, fish and arthropods, including ‘millipedes’. Crystallization dates for minerals in the overlying Lorne Plateau Lave are older than 425 Ma (Upper Silurian Ludfordian), yet palynological data are supposed to give an early Devonian (419 Ma) age. Detrital zircon U/Pb dates of sediments enclosing the fish beds give two clusters of dates, one Proterozoic and the other Silurian. The most concordant youngest single grain date of 427.0 ± 4.5 Ma (0% discordance) gives the maximum age of the Fish beds and is consistent that the radiometric dates of the overlying rapidly erupted lavas. This maximum age is slightly older than that of the ‘millipede’-bearing Cowie fish bed with maximum age of 414.3 ± 7.1 Ma, which make the Kerrera ‘millipedes’ the oldest so far dated. [ABSTRACT FROM AUTHOR]

Braided rivers can provide substantial recharge to regional aquifers, with flow exchange between surface water and groundwater occurring at a range of spatial and temporal scales. However, the difficulty in measuring and modelling these complex and dynamic river systems has hampered process understanding and the upscaling necessary to quantify these fluxes. This is due to an incomplete understanding of the hydrogeological structures that control river–groundwater exchange. In this paper, we present a new conceptualisation of subsurface processes in braided rivers based on observations of the main losing reaches of three braided rivers in Aotearoa / New Zealand. The conceptual model is based on a range of data, including lidar, bathymetry, coring, particle size distribution, groundwater level and temperature monitoring, radon-222, electrical-resistivity tomography and fibre-optic cables. The combined results indicate that sediments within the recently active river braidplain are distinctive, with sediments that are poorly consolidated and better sorted compared with adjacent deposits from the historical braidplain that become successively consolidated and intermixed with flood silt deposits due to overbank flow. A distinct sedimentary unconformity, combined with the presence of geomorphologically distinct lateral boundaries, suggests that a "braidplain aquifer" forms within the active river braidplain through the process of sediment mobilisation during flood events. This braidplain aquifer concept introduces a shallow storage reservoir to the river system, which is distinct from the regional aquifer system, and mediates the exchange of flow between individual river channels and the regional aquifer. The implication of the new concept is that surface water–groundwater exchange occurs at two spatial scales: the first is hyporheic and parafluvial exchange between the river and braidplain aquifer; the second is exchange between the braidplain aquifer and regional aquifer system. Exchange at both scales is influenced by the state of hydraulic connection between the respective water bodies. This conceptualisation acknowledges braided rivers as whole "river systems", consisting of channels and a gravel aquifer reservoir. This work has important implications for understanding how changes in river management (e.g. surface water extraction, bank training and gravel extraction) and morphology may impact groundwater recharge (and potentially flow, temperature attenuation and ecological resilience) under dry conditions. [ABSTRACT FROM AUTHOR]

Erosion of banks and channel migrations are usually common phenomenon and recurring geo-hazardous problem in the Brahmaputra-Jamuna river system of Bangladesh. The present study intensively analysed multi-temporal Landsat satellite imageries (Landsat MSS, Landsat TM, Landsat ETM+, Landsat OLI TIRS), historical documents (Hunter maps), and literature information employing Remote Sensing and Geographic Information System techniques, and estimation of braiding and sinuosity indices especially emphasizing channel bar development, braiding, and bank-line migration of the river. The computed braiding indices of the river were 1.5, 10.3, 13.4, 11.0, 10.6 and 14.6 for the year of 1853–1857, 1977, 1989, 2000, 2014 and 2018, respectively (overall deciphering increasing trend). Similar to the braiding indices, the sinuosity indices (2.58, 7.02, 9.92, 8.31, 7.42 and 11.25 for the same selected years) of the river have also been changed over time. During 1853–1857 to 2018, 766.7 and 1624.2 km2 of lands extensively eroded on the east and west bank, respectively at a rate of 4.8 and 10.1 km2 yr−1. However, from 1977 to 2018, the erosion rates were 14.4 and 12.5 km2 yr−1, respectively. High discharges, sediment transport associated with random bars formation related braiding expansion, and weak bank materials are presumably the governing factors for causing such simultaneous severe bank erosion and remarkable bank-line migration phenomenon. Although, from 1853–1857 to 1977 the erosion of the river followed the river flow direction. It is expected that the outcomes of this research can contribute further research on morphodynamic characteristics of the braided river for better understanding the river characteristics, the river hydromorphology, water and sediment transport, its bank erosion, and formulating protective measurement plan for their sustainable current flow path maintenance. [ABSTRACT FROM AUTHOR]

The Early‐Middle Jurassic is one of the crucial coal‐forming geologic periods in the world and an important target for hydrocarbon exploration in the Turpan‐Hami Basin, China. The paleoenvironment and vegetation reconstruction of the Early‐Middle Jurassic have been investigated using elemental geochemistry and palynological analysis to reveal paleoclimate evolution. A total of 48 genera of pteridophyte spore and 35 genera of gymnosperm pollen were identified, and 5 palynological assemblages were longitudinally divided, which showed significant differences in geochemical behaviours. The paleoenvironment was a transition from suboxidation to anoxia and then to an oxidation environment under freshwater conditions. The paleowater in the northern Taibei Sag was deeper than that in the southern part during the Middle Jurassic, which coincided with the sedimentary background of the sublacustrine fan in the north and the shallow braided river delta in the south. The paleovegetation evolved from mixed lowland–upland forest in the Hettangian‐Toarcian, to lowland fern forest in the Aalenian‐Bajocian, to upland conifers forest in the early Bathonian, to upland Cheirolepidiaceae forest in the late Bathonian‐Callovian. The Toarcian and Bathonian‐Callovian arid climate and the Hettangian‐Pliensbachian and Aalenian‐Bajocian warm‐humid climate were responses to the continued global warming events and the intensification of the East Asian monsoon circulation, respectively. The influence of the Bathonian‐Callovian aridification event on the sedimentary response in the southern Taibei Sag will be delayed due to the gradual southward migration of the depositional centre. [ABSTRACT FROM AUTHOR]

The river morphology of a braided‐type river is rather complex. High sediment transport rates and frequently changing discharges are the cause of dynamic planform evolution. Over the past few decades, scientific attention has been directed toward understanding the coexistence of alternating bars and the consequent emergence of confluences and divergences, all of which interact intricately with the process of bank erosion. It is still rather challenging to estimate or predict the total sediment transport rate in this type of river, especially by considering various hydrologic data and climate effects. This study is focused on the reach of the Devoll River in Albania, located upstream of the Banja dam. Understanding the morphodynamics of this river reach holds significance due to the expanding delta upstream of the dam reservoir. The objectives of the two‐dimensional depth‐averaged approach of the present study are to investigate the temporal variation of braided intensity of Devoll River and the effect of using a discharge hydrograph from hydrologic data compared to the regulated one from the upstream dam on the morphodynamics and sediment transport of the river. After evaluating various parameters such as 11 different sediment transport functions, the best results were reached for a cell size of 5 × 5 m2, Manning roughness coefficient of 0.03, Meyer‐Peter and Müller's sediment function, Hayashi et al. (1980) hiding function, and Van Rijn bed roughness predictor in this study. In addition, the results of comparing satellite images and modeling the river from 2019 to 2023 show that the braided index decreased, and this can be due to the fact that the real scenario of the river has a regulated discharge compared to the non‐regulated discharge from hydrologic data, in the mentioned period. [ABSTRACT FROM AUTHOR]

River regulation by dams and embankments drastically reduce/alter flow, which affects the natural channel pattern. Existing braiding indices have seldom incorporated the effects of diurnal flow variations caused by hydropeaking, leading to over/underestimation of the braiding intensity. These indices consider only the visible wet channels, ignoring the existence of dry channels that are activated only episodically during phases of water release from hydropower dams. We have extracted the dry channels (those that are periodically wet) coursing across the channel belt of the highly regulated River Tista from Landsat images between 1977 and 2014, using Normalized Difference Wetness Index values. These were combined with existing wet channel widths and numbers to formulate the Regulated Braiding Index (RBi) for characterizing channel braiding in the Tista's course over the Himalayan foothill plains. Overall, the widths and numbers of wet channels decreased by 63% and 25%, respectively, during the regulated years (2003 and 2014) as compared to pre‐dam years (1977 and 1995) due to the collective operation of 14 upstream dams/barrages (having cumulative ~89 million m3 reservoir capacity), whose operations reduced the braiding intensity (eliciting lower RBi values). Further, the number of high braiding reaches decreased by half while low braiding stretches rose by 10% in comparison to the pre‐dam period due to reduced/regulated flow. Comparative analysis of derived RBi values with three existing braiding indices revealed that RBi values consistently decreased near barrages, bridges, and within embankment‐confined reaches, unlike the other indices, thus providing a better framework for assessing expected river regulation effects. [ABSTRACT FROM AUTHOR]

Modeling inclined fine‐scale mud drapes inside point bars, deposited on accretion surfaces during stages of low energy or slack water, is critical to modeling fluid flow in complex sedimentary environments (e.g., fluvial and turbidity flows). These features have been modeled using deterministic or geostatistical modeling tools (e.g., object‐, event‐, and pixel‐based). However, this is a non‐trivial task due to the need to preserve geological realism (e.g., connectivity within sedimentary features and facies hierarchy), while being able to condition the generated models to point data (e.g., well data). Generative Adversarial Networks (GAN) have been successfully applied to reproduce several large‐scale scenarios (e.g., braided rivers and carbonate reservoirs), yet their potential for capturing small‐scale and hierarchical features remains largely unexplored. Here, we propose a geo‐modeling workflow for fast modeling of small‐scale conditional mud drapes based on ALLUVSIM and GANSim. Initially, improved ALLUVSIM produces realistic unconditional models of mud drapes along accretionary surfaces, serving as GAN training data. GANSim is then employed to achieve conditioning to well data and probability maps derived from geophysical modeling. Finally, temporal pressure data observed in wells are further conditioned via a Markov chain Monte Carlo sampling method. The proposed geo‐modeling workflow is validated in a two‐dimensional synthetic example as the pre‐trained generator extracts mud‐drapes‐features and generates multiple facies realizations conditioned to diverse information. A field application example in a modern meandering river verifies the effectiveness and practicability of the proposed workflow in real case application examples. The application examples illustrate the potential of the proposed method to predict mud drapes inside point bar reservoirs. Key Points: The proposed method achieves fast conditional mud drapes stochastic modelingThe effectiveness and applicability of the proposed method have been verified in modern channel depositThe proposed method provides technical support for future predictions of mud drapes inside underground point bar reservoirs [ABSTRACT FROM AUTHOR]

Aridification of Central Asia in the Late Mesozoic led to drastic environmental changes characterized by widespread aeolian deposits. We systematically investigated fluvial‐aeolian deposits in the Middle Jurassic Toutunhe Formation, Upper Jurassic Kalazha Formation, and Lower Cretaceous Tugulu Group in the Junggar Basin to the north of the Tianshan Orogenic Belt via unmanned aerial vehicle‐based photogrammetry, scanning electron microscope, grain‐size analysis, and detrital zircon geochronology. Paludal and deltaic environments transitioned to a fluvial‐aeolian environment from the late Middle Jurassic to the Late Jurassic. Fan delta and incisive braided river deposits accumulated in the earliest Cretaceous and evolved into a lacustrine environment with aeolian deposits in the lakeshore. Aeolian deposits are characterized by moderate‐ to well‐sorted and subangular to subround sandstones with large‐scale, high‐dip cross‐bedding, inversely graded lamination, dominant saltation grains, crescent‐shaped, and dish‐shaped impact structures. Aeolian deposits contain heavy minerals including more ilmenite, zircon, garnet, and, tourmaline and less magnetite and epidote than the fluvial deposits. The preserved aeolian sediments of the Kalazha Formation extend west–east for more than 100 km, suggesting a wide desert area during the latest Jurassic. The detrital zircon age patterns indicate that the provenance of the aeolian deposits was similar to that of coeval fluvial deposits. The cooccurrence of fluvial and aeolian deposits and the similar provenances but orthogonal flow directions indicate that the aeolian deposits were mainly sourced from the nearby fluvial material within the basin. The evolution of the fluvial‐aeolian system responded to a complete base‐level cycle controlled by the aridification and tectonics. Due to decreased sediment supply caused by aridification, the base level rose, leading to the change from braided rivers to meandering rivers, along with the deposition of aeolian sediments. Due to the tectonic reactivation in the Late Jurassic, the base level fell, causing the occurrence of alluvial fans and the expansion of the aeolian sediments. Previous studies revealed that the Tianshan in the Jurassic exhibited low relief. The fluvial‐aeolian system played an important role in maintaining the limited relief in southern Central Asia. [ABSTRACT FROM AUTHOR]

In order to understand the problem of sediment sources in the Xujiahe Formation of the Central Sichuan Uplift, high-density two-dimensional seismic data was used, and LCS2 (the second section of the Xujiahe Formation) was taken as the research object. Combined with logging interpretation results, typical seismic facies were identified within the sequence, including clinoform seismic facies, progradational reflection seismic facies, and incised valley seismic facies. The progradational reflection seismic facies can be divided into two types: S-shaped and oblique progradational reflection facies. The oblique progradational reflection seismic facies representing the rapid filling environment of sediments are mainly distributed in the southeast of the study area, while the northwest mainly develops relatively low-energy sedimentary mechanisms of S-shaped seismic facies. The incised valley seismic facies are mainly distributed in the eastern and southeastern parts of the work area. On the plane, the incised valley seismic facies have a trend of gradually widening and shallowing towards the northwest direction. In addition, the distribution of sedimentary facies was analyzed using seismic attributes. The southeastern and central parts of the study area are mainly composed of proximal sand-rich braided river alluvial plains, while the northwestern part is mainly composed of distal mud-rich braided river alluvial plains. The distribution of sedimentary facies generally shows a southwest to northeast distribution. From southeast to northwest, the sedimentary facies show a clear trend of changing from sand-rich to mud-rich. Based on the comprehensive distribution characteristics of seismic and sedimentary facies, it is believed that the river in the Central Sichuan Uplift basically enter the region from the south or southeast, and transport sediments from southeast to northwest. Based on the above evidence, it is inferred that the sedimentary material of the Xujiahe Formation in the Central Sichuan Uplift mainly comes from the «Qianzhong Ancient Uplift» or «Fanjing Mountain Ancient Land» on the southern and southeastern of the Sichuan Basin. [ABSTRACT FROM AUTHOR]

The Dunhuang Basin, situated in western China along the Altyn Tagh Fault (ATF) zone, intersects the Tethys and Paleo‐Asian Ocean tectonic domains. Influenced by both the ATF system and the far‐field effects of the Qiangtang‐Lhasa‐Eurasia collision during the Mesozoic, the mechanism of the Jurassic sedimentary migration of the basin in response to tectonic movements is unclear so far. The paper uses a comprehensive approach, including field geological surveys, lithologic and lithofacies discern, stratigraphic relationships analysis and 2D seismic profile interpretation, to examine the distribution of Jurassic residual strata in the basin. The comprehensive results of our study suggest that the Dunhuang Basin exists as an isolated block with unique tectonic and sedimentary evolution characteristics. In the Early Jurassic, the Dunhuang Basin underwent initial rifting, leading to the formation of small segmented intermontane sags. This phase was marked by the coarse particle sedimentary system of alluvial fans and braided rivers, represented the near source rapid deposition in the initial formation period of the basin. Stratigraphic distribution was primarily influenced by pre‐Jurassic basement topography and was not significantly constrained by faulting during this period. The formation of these isolated discontinuous small intermontane sags indicates the segmented activities of the ATF in the Early Jurassic period. In the Middle Jurassic period, influenced by the ATF dextral strike‐slip faulting, sedimentation extended eastward and the depocenter migrated clockwise compared with the distribution of the Middle Jurassic strata within the Dunhuang Basin. This period witnessed the development of coal measure strata at the basin's margins and lacustrine fine‐grained clastic deposition in the centre. The segmented fracture of the ATF gradually initiated a unified dextral strike‐slip tectonic movement. In the Late Jurassic period, sedimentary strata were locally present in the Wanyao Sag but absent in other sags. The depocenter migrated counterclockwise compared with the distribution of Middle Jurassic strata within the Dunhuang Basin, due to regional uplift accompanied by the ATF sinistral strike‐slip faulting caused by the collision between the Lhasa Block and the Eurasia Plate. The depocenter migration of the Dunhuang Basin constrained within the ATF system from the Early to Middle and Late Jurassic can be attributed to the transition of the ATF strike‐slip faulting in context of the stress relaxation and compression between the collision of the Qiangtang and Lhasa blocks to the Eurasia Plate, respectively. [ABSTRACT FROM AUTHOR]