Scroll Bars Research Articles

GEOMORPHOLOGICAL MAPPING OF PART OF THE NIGER DELTA, NIGERIA USING DEM AND MULTISPECTRAL IMAGERY

This study utilised geo-information technology to carry out a geomorphological mapping of a part of the Niger Delta. Satellite image analysis was based on bi-annual seasonal approach using a combination of visual analysis of the geometry, site, situation, colour, and season for analysis of the non-topographic features. The study also utilised virtual and onsite fieldworks and existing geomorphologic information to interpret and analyse topographic and bathymetric features. First-order topographic features (elevation) and second level features including slope, aspect, curvature and mathematically exaggerated shaded relief were extracted from DEM. Relief classification was based on average elevation differences, hill shade, slope, and aspect. Three main non-topographic landforms were identified; the permanent rivers with stable meanders, perennially-active systems of creeks and fluvial landforms including scroll bars and oxbows. With the exception of higher elevation values towards the north-western fringe, the elevation ranges between mean sea level and 1 metre above sea level thus establishing a somewhat flat terrain. These areas were filled with meandering streams, sinuous creeks and watercourses flanked by mangrove vegetation. In the north-western area, elevation rose close to approximately 4 metres in most of the area with a peak of 10 metres. Generally, the cumulative area-slope analysis yielded a deltaic plain with generalised slope ≤ 20. Overall two elevation-based geographically differentiated morphological units were identified; tidal mudflats and saltmarshes. The study recommends that to provide needed information for resource planning and management, further investigation should be carried out with a view to modelling probable ecological and geomorphological changes in the entire Niger Delta.
 

Reproducible Research and Reports with R

We have all had the experience of having performed a laborious calculation in a spreadsheet program only to later be required to redo the analysis because of the availability of additional data, the discovery of an error, or because the analysis is part of a recurring report (e.g., monthly quality indicators). At that point we may have to return and begin the calculation all over, except we may not even remember what we did, or we may inadvertently perform the analysis in a slightly different way each time. Another common issue is that we may have a data set so large that using a spreadsheet program may be impractical—move scroll bar, watch program freeze, …

Scroll bars are inner bank levees along meandering river bends

AbstractScroll bars across a 65‐km stretch of the Trinity River in Texas, USA were studied using LiDAR data as well as with a series of 11 trenches spread out across the survey area. We conclude that scroll bars are levees that are deposited along the inner banks of these meandering river bends. Scroll bar crests were found to have similar elevations to those of outer bank levee crests, implying that they are constructional features that create positive topographic relief above the elevation of the floodplain. Trenches reveal that scroll bars are built from reworked suspended sediment, with common ripple‐scale cross stratification, planar laminations and muddy bioturbated layers – characteristics often associated with levee sedimentation in other systems. LiDAR observation of the erosion of scroll bars by bed material transport during flood implies that scroll bar spacing is an imperfect proxy for estimating overall channel migration rates. In addition, interspersed lenses of coarser sediment with dune‐scale cross stratification represent the stratigraphic record of these erosional events and suggest that erosion of the channel‐ward edge of the scroll bar is not uncommon. Preservation of scroll bars is unlikely, given that they are responsible for an average of only the uppermost 12% of the total inner bank relief. We suggest that misidentification of point bar lateral accretion surfaces as scroll bars is common and can lead to issues with reconstructing channel properties due to systematic differences between point bar and scroll bar planform geometries. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.

Quaternary meandering evolution and architecture of a point bar in the Mun River on the sandstone-dominated Khorat Plateau from northeastern Thailand

The Mun River, the main right bank tributary of the Mekong River, meanders and flows eastwards across the flat and sand-dominated low-lying plain of the Khorat Plateau, northeastern Thailand. The Mun River expresses its evolution with a spectacular trace of its meander landforms on the floodplain surface. This paper reveals (for the first time) the three-dimensional shallow subsurface sedimentary architecture inside a part of a sandy point bar deposit of the Mun River based on ground penetrating radar (GPR) in comparison with outcrop observation from a road cut along the GPR line survey. As a result, we recognized subsurface scroll bars, where the expansion, rotation and transformation types corresponded well with the sedimentary structures exposed on the road cut. Dominant GPR radar facies included hummocky/wavy, group of fitful waves, shingled, curved down pattern, 15–45 degree of reflection angle, sigmoid, sets of en-echelon or sigmoid, concaved upward and isolated trough shape, parallel, horizontally continuous layers and parabolic facies. These GPR facies possibly inferred the sedimentary structures of trough cross-bedded, channel-fills, side bar deposit, erosion surface of channel or chute cut-off, secondary channel scours and fills, horizontal sand-bedded and sheet flood sand. Both GPR facies and lithofacies revealed the meandering evolution of a bar-parallel and bar-transverse mid-channel bar with small braided channels on the bar top and showed the lateral migration of the point bar.

Lesion Localization Using Digital Breast Tomosynthesis: Where Did I Go Wrong?

The scroll bar on digital breast tomosynthesis has become an imperative tool that breast imaging radiologists rely on for help in identify lesions on the orthogonal view, targeting breast ultrasound, and performing challenging biopsies for one-view findings. The ability to predict the lesion location using the scroll bar not only saves time in the diagnostic setting but also reduces screening recalls when a finding can be confirmed as dermal. It is important, however, to recognize settings in which the location prediction can be misleading, such as for lesions in thin breast tissue or the anterior portion of the breast or if the breast is not appropriately positioned. In these situations, radiologists can use other diagnostic tools for problem solving.

The role of Late Pleistocene-Holocene tectono-sedimentary history on the origin of patches of savanna vegetation in the middle Madeira River, southwest of the Amazonian lowlands

Savanna patches are features of the Amazonian landscape that have been long under intense debate, but there are still questions about the main factors that have determined their establishment and evolution within the rainforest matrix. In particular, their geological substrates were poorly documented. The aim of this work is to reconstruct the tectono-sedimentary history of four savanna patches in the middle Madeira River, southwest Amazonia, and discuss its potential control over the development of the savanna communities. The approach consisted in the integration of geomorphological, sedimentological, chronological and floristic data. The results revealed that the savanna substrates are sandy deposits aged between 118.9 and 35.6 ky, overlain by late Pleistocene to Holocene muddier successions <25,700 cal yr BP. Most of the geologically stable and topographically higher terrains of the geomorphological unit T1 is dominated by forests. These intermingle with open habitats formed by renewed sedimentation that were colonized by tree and shrub species of the Amazonian biome. By contrast, the ground of unit T2 subsided to a level that allowed the meandering of the main river. This process resulted in the replacement of the rainforest by open habitats dominated by savannas with lower richness and diversity than in the T1 unit, which were dominated by species with wide distribution in the cerrado biome of Central Brasil. The cerrado species might have expanded into this region during Pleistocene drier climatic episodes, but environmental filters shaped by geological processes determined the floristic contrasts between units T1 and T2. The lack of competition with Amazonian species probably constituted an important factor for the preferential colonization of arboreal and shrubby species from neighboring cerrados on meandering scroll bars, marginal levees and crevasse splays of unit T2.

The Archival Impulse and the Editorial Impulse

There is no firm, outside vantage-point from which to survey and thus to define archive and edition as securely differentiated categories. As readers we inhabit the same textual field as the approaches to documents and texts that we seek to define. To record is first to read and analyse sufficiently for the archival purpose; to interpret is first to read and to analyse sufficiently for the editorial purpose. In practice, the archival impulse anticipates the editorial, and the editorial rests on the archival. We may envisage the relationship of archive and edition as a horizontal slider or scroll bar running from archive on the left to edition on the right. In this model every position on the slider involves interpretative judgement appropriate to its purpose. Every position along the slider involves a report on the documents, but the archival impulse is more document-facing and the editorial is, relatively speaking, more audience-facing. Yet each activity, if it be a scholarly one, depends upon or anticipates the need for its complementary or co-dependent Other. The archival impulse aims to satisfy the shared need for a reliable record of the documentary evidence; the editorial impulse to further interpret it, with the aim of orienting it towards known or envisaged audiences and by taking their anticipated needs into account. The sliding scroll-bar model dispenses with recently expressed anxiety about digital literary archives (special-purpose collections) replacing editions. The latter will continue to be prepared as long as there are readers whose requirements need to be served. The slider model helps us to survey the full range of archival and editorial possibilities. The term “representation” embraces the archival impulse. The editor’s aim, on the other hand, is less to represent something that is pre-existing than to present something (the text of a version, the text of a work, a process of writing) that typically has not existed in precisely this form before, together with the critically analysed materials necessary to defend the presentation.

Interflag sandstone laminae, a novel sedimentary structure, with implications for Ediacaran paleoenvironments

Interflag sandstone laminae are thin, silty to sandy, layers between thicker sandstone beds, and a new name for sedimentary structures recently called “shims”, and “microbial mat sandwiches”, from Ediacaran fossil localities of Nilpena, South Australia. They have been regarded as structures unique to Precambrian marine environments, but both the age and environmental associations are reinterpreted in this study. Interflag sandstone laminae from Eocene (Wasatch Formation, Colorado, U.S.A.) and Pennsylvanian (Mansfield Formation, Indiana, U.S.A.) fluvial levees and scroll bars were studied in the field, and by means of petrographic thin sections and granulometry. Climbing translatent ripples and distinct grain size distributions are evidence that interflag sandstone laminae were eolian, whereas intervening flagstones were deposited by fluvial traction currents. Other evidences of exposure to wind include microbial earth textures, shallow cracking structures, zibars, setulfs, root traces, and insect trackways. Other evidences of flagstone deposition in traction currents include intraformational claystone breccias, oscillation and current ripples, and microbial mat textures. Similarly distinct beds can be seen in modern sandy river levees, such as the Murchison River of Western Australia and Green River of Utah (U.S.A.). These observations reveal that interflag laminae are created by exposure and wind-drift, but flagstones are produced by floods. Quartzose flagstones of demonstrable marine origin, with fossil brachiopods and trilobites, have also been examined, but lack interflag sandstone laminae. Interflag sandstone laminae are evidence of alternating flood and wind, only known from fluvial environments, and are further support for the idea that Ediacaran vendobionts from South and central Australia, and Namibia lived on land.

Point bar sedimentation and erosion produced by an extreme flood in a sand and gravel-bed meandering river

In fluvial environments, extreme floods are often catalysts for substantial geomorphologic planform change. Despite the significant sediment erosion and deposition associated with high-magnitude, low-frequency floods, their sedimentological products often lack distinctive characteristics. However, the sedimentological expression of extreme floods in sand and gravel-bed meandering rivers has yet to be fully described. The sedimentological characteristics of a 1 in 100 year flood on a point bar of the South Saskatchewan River in Alberta, Canada, are investigated. Digital elevation models from multitemporal LiDAR surveys, field sediment sampling, measured sections, shallow boreholes, and aerial photographs were used to identify regions of sediment deposition and erosion, quantify the amount of vertical elevation change, and describe the sedimentology, stratigraphy and grain-size distribution of the flood deposit. The upstream portion of the point bar was dominated by high-velocity flow and erosion. The majority of sedimentation occurred at the meander-bend apex in lee and scroll bars composed of medium- to coarse-grained sand. Downstream of the bend apex, very fine- to fine-grained sand beds accumulated on ridges and lee bars. Silt, <10 cm thick, was deposited in the point bar interior. No single grain size or sedimentary structure typifies the flood deposit. Sedimentological evidence of extreme floods on point bars are likely best preserved in floodplain strata (rather than in-channel strata) and consist of beds with a coarser texture than what is normally dominant at that position on the point bar. In particular, the presence of gravel beds at high stratigraphic elevations appears indicative of an extreme-flood event. These criteria have been used to identify extreme-flood sediments in other coarse-grained point-bar deposits and may be applicable to the deposits of braided and wandering rivers, or lower-competence meandering rivers.

Late Holocene channel pattern change from laterally stable to meandering – a palaeohydrological reconstruction

Abstract. River channel patterns may alter due to changes in hydrological regime related to changes in climate and/or land cover. Such changes are well documented for transitions between meandering and braiding rivers, whereas channel pattern changes between laterally stable and meandering rivers are poorly documented and understood. We hypothesize that many low-energy meandering rivers had relatively low peak discharges and were laterally stable during most of the Holocene, when climate was relatively stable and human impact was limited. Our objectives in this work are to identify a Late Holocene channel pattern change for the low-energy Overijsselse Vecht river, to develop and apply a novel methodology to reconstruct discharge as a function of time following a stochastic approach, and to relate this channel pattern change to reconstructed hydrological changes. We established that the Overijsselse Vecht was laterally virtually stable throughout the Holocene until the Late Middle Ages, after which large meanders formed at lateral migration rates of about 2 m yr−1. The lateral stability before the Late Middle Ages was constrained using a combination of coring information, ground-penetrating radar (GPR), radiocarbon (14C) dating, and optically stimulated luminescence (OSL) dating. We quantified bankfull palaeodischarge as a function of time based on channel dimensions that were reconstructed from the scroll bar sequence and channel cut-offs using coring information and GPR data, combined with chronological constraints from historical maps and OSL dating. We found that the bankfull discharge was significantly greater during the meandering phase compared to the laterally stable phase. Empirical channel and bar pattern models showed that this increase can explain the channel pattern change. The bankfull discharge increase likely reflects climate changes related to the Little Ice Age and/or land use changes in the catchment, in particular as a result of peat reclamation and exploitation.

Reconstructing lateral migration rates in meandering systems – a novel Bayesian approach combining optically stimulated luminescence (OSL) dating and historical maps

Abstract. Identifying lateral migration rates of meandering rivers is relevant both for fluvial geomorphology and to support river management. Lateral migration rates for contemporary meandering systems are often reconstructed based on sequential remote-sensing images or historical maps; however, the time frame for which these sources are available is limited and hence likely to represent fluvial systems subjected to human influence. Here, we propose to use scroll bar sequences as an archive to look further back in time using optically stimulated luminescence (OSL) dating of sand-sized quartz grains. We develop a modelling procedure for the joint Bayesian analysis of (OSL) dating results and historical map data. The procedure is applied to two meanders from the Overijsselse Vecht, a medium-sized sand-bed river in the Netherlands. We obtained nine samples for OSL dating from scroll bars and combined OSL dating results with historical map data for the period 1720–1901 CE (Common Era). The procedure we propose here incorporates the strengths of both data types for reconstructing fluvial morphodynamics over longer time frames. Using an iterative modelling approach, we translate spatial uncertainty of historical maps into temporal uncertainty of channel position required for Bayesian deposition modelling. Our results indicate that meander formation in the Overijsselse Vecht system started around 1400 CE, and lateral migration rates were on average 2.6 and 0.9 m yr−1 for the two investigated bends, until river channelization around 1900 CE.

Image annotation tactics: transitions, strategies and efficiency

Human interpretation of images during image annotation is complicated, but most existing interactive image annotation systems are generally operated based on social tagging, while ignoring that tags are insufficient to convey image semantics. Hence, it is critical to study the nature of image annotation behaviors and process. This study investigated annotation tactics, transitions, strategies and their efficiency during the image annotation process. A total of 90 participants were recruited to annotate nine pictures in three emotional dimensions with three interactive annotation methods. Data collected from annotation logs and verbal protocols were analyzed by applying both qualitative and quantitative methods. The findings of this study show that the cognitive process of human interpretation of images is rather complex, which reveals a probable bias in research involving image relevance feedback. Participants preferred applying scroll bar (Scr) and image comparison (Cim) tactics comparing with rating tactic (Val), and they did fewer fine tuning activities, which reflects the influence of perceptual level and users’ cognitive load during image annotation. Annotation tactic transition analysis showed that Cim was more likely to be adopted at the beginning of each phase, and the most remarkable transition was from Cim to Scr. By applying sequence analysis, the authors found 10 most commonly used sequences representing four types of annotation strategies, including Single tactic strategy, Tactic combination strategy, Fix mode strategy and Shift mode strategy. Furthermore, two patterns, “quarter decreasing” and “transition cost,” were identified based on time data, and both multiple tactics (e.g., the combination of Cim and Scr) and fine tuning activities were recognized as efficient tactic applications. Annotation patterns found in this study suggest more research needs to be done considering the need for multi-interactive methods and their influence. The findings of this study generated detailed and useful guidance for the interactive design in image annotation systems, including recommending efficient tactic applications in different phases, highlighting the most frequently applied tactics and transitions, and avoiding unnecessary transitions.

Electrical resistivity imaging of anastomosing river subsurface stratigraphy and possible controls of fluvial style change in a graben-like basin, Czech Republic

Subject to frequent channel avulsions due to the increased frequency of floods, rise of base level, and/or sediment overloading, anastomosing rivers are sensitive to external (climatic or tectonic) forcing in sedimentary basins. The Morava River, Czech Republic, shows a well-developed Holocene anastomosis, confined to the pull-apart type Upper Morava Basin (UMB). We studied the stratigraphy and aggradation rates of the UMB using electrical resistivity tomography (ERT), dipole electromagnetic profiling (DEMP), core data, and radiocarbon ages, with the aim of identifying factors triggering the anastomosis at the Pleistocene/Holocene transition. The ERT and DEMP proved to be excellent tools to visualize the shape and thickness of floodplain depositional units (abandoned meanders, scroll bars, etc.). The major geophysical surfaces identified are the base of the late Weichselian braided-stream deposits (OSL age = 34.53 ± 3.42 ka), interpreted as a palaeo-stream gradient of the Morava River, and their transition to Holocene floodplain deposits. In the late Weichselian, the river aggraded at an average rate of 0.2 mm/yr. The Holocene (oldest 14C age = 7.066 ± 0.072 ka) short-term aggradation rates reached up to 13.7 mm/yr, but the average long-term rates (~0.07 to ~0.4 mm/yr) are comparable to the late Weichselian. The stratigraphy and sediment ages indicate that the onset of anastomosis was not likely associated with accelerated basin subsidence. Possible controls of the anastomosis include upstream control by numerous tributaries, large wood debris in the floodplain forests, and changes in land use. The tectonic and geomorphic context of the UMB pull-apart basin probably favoured the development of the anastomosis.

Decadal scale geomorphic changes and tributary confluences within the Ganga River valley in Varanasi region, Ganga Plain, India

Allahabad to Buxar, the Ganga River shows distorted menders, huge meander cut-offs, ox-bow lakes, scroll bars and abandoned linear channel belts, all suggesting to a fault system-related tectonic control on the river. The confluence dynamics of northern tributaries Gomati and Varuna Rivers which have shifted progressively from north to south, and confluences of southern tributary Jirgo which shifted from south to north, further corroborate the view and also suggest that the presence of a NE-SW trending dextral strike slip fault having a gravity component.The Ganga River came close to Varanasi around 40 ka ago following a tectonic event that caused extensive liquefaction of the sediments due to a seismic pulse and upheaval in the area. Between 40 to 7ka, the Ganga River was freely oscillating within its valley when another tectonic event took place and the Ramnagar cliff was raised due to upheaval and channel incision along NE-SW trending fault. After 7ka, the Ramnagar cliff was degraded before it was inhabited by man at around 3800 years BP, which have been contemporaneous to antiquity of Varanasi.Based on available remote sensing data, the morphometry has shown that in 1972 active channel covered 12% area in Ganga River Valley and aerial extent remained 8% in 2010. The decrease of sand bar areas (14%–11%) in the studied stretch reflects the decrease in monsoon strength over the last four decades. However, the decline in the aerial extent of relict valley features, viz. meander scars, meander cut-offs and alluvial islands, is quite characteristic and may be related to sediment recycling by migrating channels present within the active channel belt and floodplain areas of the Ganga River.

Using Time‐Lapse Lidar to Quantify River Bend Evolution on the Meandering Coastal Trinity River, Texas, USA

AbstractTime‐lapse airborne lidar on the coastal Trinity River in Texas, USA, shows profound downstream variability in point bar growth and cut bank erosion resulting from a historically large flood that occurred in 2015. The difference map generated from two surveys covers 55 river bends and captures the transition from quasi‐uniform flow into backwater flow. In the upstream portion of the survey, reach‐averaged deposition is greater than erosion, with high local variability between the two due to the occurrence of bend cutoffs. Point bars shift laterally up to 3 times as much as cut bank retreat in this area. In the backwater zone, cut bank erosion consistently outpaces deposition on point bars and cut bank retreat exceeds the lateral shift of the point bar. Edge‐to‐edge channel width, measured from active scroll bar to outer bank, increases for all bends. This widening is often partially due to point bar widening and movement of the scroll bar away from the channel. The combination of net erosion and limited lateral movement of point bars within the backwater zone implies that during large sustained floods, bank pull instigates channel migration in this area. Farther upstream, net deposition and the high ratio of point bar to cut bank lateral motion imply bar push is more important. Patterns of deposition and erosion within a single bend suggest that channel migration was dominated by downstream bend translation with little bend deformation. Results from this study help to deepen the understanding of coastal river system morphodynamics by connecting changes in the geomorphology to changes in river bend kinematics, hydraulics, and sediment transport.

Morphology and spacing of river meander scrolls

Many of the world's alluvial rivers are characterised by single or multiple channels that are often sinuous and that migrate to produce a mosaicked floodplain landscape of truncated scroll (or point) bars. Surprisingly little is known about the morphology and geometry of scroll bars despite increasing interest from hydrocarbon geoscientists working with ancient large meandering river deposits. This paper uses remote sensing imagery, LiDAR data-sets of meandering scroll bar topography, and global coverage elevation data to quantify scroll bar geometry, anatomy, relief, and spacing. The analysis focuses on preserved scroll bars in the Mississippi River (USA) floodplain but also compares attributes to 19 rivers of different scale and depositional environments from around the world.Analysis of 10 large scroll bars (median area = 25 km2) on the Mississippi shows that the point bar deposits can be categorised into three different geomorphological units of increasing scale: individual ‘scrolls’, ‘depositional packages’, and ‘point bar complexes’. Scroll heights and curvatures are greatest near the modern channel and at the terminating boundaries of different depositional packages, confirming the importance of the formative main channel on subsequent scroll bar relief and shape. Fourier analysis shows a periodic variation in signal (scroll bar height) with an average period (spacing) of 167 m (range 150–190 m) for the Mississippi point bars. For other rivers, a strong relationship exists between the period of scroll bars and the adjacent primary channel width for a range of rivers from 55 to 2042 mis ~50% of the main channel width. The strength of this correlation over nearly two orders of magnitude of channel size indicates a scale independence of scroll bar spacing and suggests a strong link between channel migration and scroll bar construction with apparent regularities despite different flow regimes. This investigation of meandering river dynamics and floodplain patterns shows that it is possible to develop a suite of metrics that describe scroll bar morphology and geometry that can be valuable to geoscientists predicting the heterogeneity of subsurface meandering deposits.

Need for diagnostic-centric care in dentistry: A case study from the Marshfield Clinic Health System

BackgroundThe study objective was to evaluate the workflow of dental providers who use the existing electronic dental record (EDR) system at a large regional health care system to establish a diagnostic-centric culture as part of their dental practice. A further goal focused on identifying when improvements to the workflow and design of the EDR may be indicated. MethodsDental procedures performed on patients and corresponding International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnoses were retrospectively mined from Marshfield Clinic’s enterprise data warehouse. All dental procedures performed were selected and paired with corresponding diagnostic codes documented by dental providers. Frequency of documented diagnosis was further analyzed by characterizing correspondence with their ranking order in the diagnosis column with and without a scroll bar within the EDR user interface (UI). Accuracy of selecting appropriate ICD-9-CM for the corresponding Code on Dental Procedure and Nomenclature (CDT) was checked for 10% (n = 6,187) of the procedure-diagnosis pairs. ResultsOf the 61,511 unique procedures documented using 147 CDTs, 11% (6,914 procedures) had a corresponding “not available” option associated under the diagnoses column, whereas 89% (54,597) of dental procedures were associated with a corresponding ICD-9-CM diagnostic code. Overall tendency of dental providers to select the first or last options from the diagnostic list with a scroll bar was noted. Appropriateness of documenting corresponding ICD-9-CM to CDT procedures indicated 98% accuracy. ConclusionEDR UI design greatly affected documentation process. Redesigning the EDR UI from the results will increase both the quality and utility of clinical documentation.

Exploring the role of trees in the evolution of meander bends: The Tagliamento River, Italy

AbstractTo date, the role of riparian trees in the formation of scroll bars, ridges, and swales during the evolution of meandering channels has been inferred largely from field observations with support from air photographs. In situ field observations are usually limited to relatively short periods of time, whereas the evolution of these morphological features may take decades. By combining field observations of inner bank morphology and overlying riparian woodland structure with a detailed historical analysis of airborne LiDAR data, panchromatic, and color images, we reconstruct the spatial and temporal evolution of the morphology and vegetation across four meander bends of the Tagliamento River, Italy. Specifically we reveal (i) the appearance of deposited trees and elongated vegetated patches on the inner bank of meander bends following flood events; (ii) temporal progression from deposited trees, through small to larger elongated vegetated patches (pioneer islands), to their coalescence into long, linear vegetated features that eventually become absorbed into the continuous vegetation cover of the riparian forest; and (iii) a spatial correspondence between the resulting scrolls and ridge and swale topography, and tree cover development and persistence. We provide a conceptual model of the mechanisms by which vegetation can contribute to the formation of sequence of ridges and swales on the convex bank of meander bends. We discuss how these insights into the biomorphological processes that control meander bends advance can inform modeling activities that aim to describe the lateral and vertical accretion of the floodplain during the evolution of vegetated river meanders.

Modeling meander morphodynamics over self‐formed heterogeneous floodplains

AbstractThis work addresses the signatures embedded in the planform geometry of meandering rivers consequent to the formation of floodplain heterogeneities as the river bends migrate. Two geomorphic features are specifically considered: scroll bars produced by lateral accretion of point bars at convex banks and oxbow lake fills consequent to neck cutoffs. The sedimentary architecture of these geomorphic units depends on the type and amount of sediment, and controls bank erodibility as the river impinges on them, favoring or contrasting the river migration. The geometry of numerically generated planforms obtained for different scenarios of floodplain heterogeneity is compared to that of natural meandering paths. Half meander metrics and spatial distribution of channel curvatures are used to disclose the complexity embedded in meandering geometry. Fourier Analysis, Principal Component Analysis, Singular Spectrum Analysis and Multivariate Singular Spectrum Analysis are used to emphasize the subtle but crucial differences which may emerge between apparently similar configurations. A closer similarity between observed and simulated planforms is attained when fully coupling flow and sediment dynamics (fully‐coupled models) and when considering self‐formed heterogeneities that are less erodible than the surrounding floodplain.

Improved Software to Browse the Serial Medical Images for Learning.

The thousands of serial images used for medical pedagogy cannot be included in a printed book; they also cannot be efficiently handled by ordinary image viewer software. The purpose of this study was to provide browsing software to grasp serial medical images efficiently. The primary function of the newly programmed software was to select images using 3 types of interfaces: buttons or a horizontal scroll bar, a vertical scroll bar, and a checkbox. The secondary function was to show the names of the structures that had been outlined on the images. To confirm the functions of the software, 3 different types of image data of cadavers (sectioned and outlined images, volume models of the stomach, and photos of the dissected knees) were inputted. The browsing software was downloadable for free from the homepage (anatomy.co.kr) and available off-line. The data sets provided could be replaced by any developers for their educational achievements. We anticipate that the software will contribute to medical education by allowing users to browse a variety of images.