13 results on '"van Dijk, Wout M"'
Search Results
2. Observed and modelled tidal bar sedimentology reveals preservation bias against mud in estuarine stratigraphy.
- Author
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Braat, Lisanne, Pierik, Harm Jan, van Dijk, Wout M., van de Lageweg, Wietse I., Brückner, Muriel Z. M., van der Meulen, Bas, and Kleinhans, Maarten G.
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SEDIMENTOLOGY ,ESTUARINE ecology ,TIDAL flats ,INTERTIDAL zonation ,FLOW velocity ,MUD ,ESTUARIES - Abstract
Mud plays a pivotal role in estuarine ecology and morphology. However, field data on the lateral and vertical depositional record of mud are rare. Furthermore, numerical morphodynamic models often ignore mud due to long computational times and simplifications of mixed depositional processes. This study aims to understand the spatial distribution, formative conditions and preservation of mud deposits in the intertidal zone of bars in high‐energy sand‐dominated estuaries, and to elucidate the effects of mud on morphology, ecology and stratigraphic architecture. To meet these objectives, field data (historic bathymetry, bio‐morphological maps and sediment cores of the shoal of Walsoorden, Western Scheldt estuary, the Netherlands) were combined with complementary hydro‐morphodynamic numerical modelling (Delft3D). Based on the field observations, two types of mud deposits were distinguished: (1) mudflat deposits, which are thick (>10 cm) mud beds at the surface associated with high elevations and low accumulation rates; and (2) mud drapes, which are thin (millimetre to centimetre) buried laminae that form and preserve at a wide range of elevations and energy conditions. Model results show that deposition on mudflats occurs just after high‐tide slack water in areas shielded from high flood velocities, suggesting that mud accumulation is mostly controlled by elevation, flow velocity and flow direction. Mud accumulation increases shoal elevation, sometimes to supratidal levels. This reduces flow over the shoal, which in turn reduces chute channel formation, stabilises bar morphology and decreases local tidal prism. These effects further promote mud deposition and vegetation settling. Although observations show that mud cover at the surface is relatively high (20%–40% of the intertidal area), mud constitutes only a small percentage of the total estuary volume (ca 5%) revealing that only a small fraction is preserved in the stratigraphy. Due to this mismatch between surface and subsurface expression of mud, interpretations of estuarine stratigraphy risk underestimating the influence of mud at the surface on morphodynamics and habitats. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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3. Observed and modelled tidal bar sedimentology reveals preservation bias against mud in estuarine stratigraphy
- Author
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Braat, Lisanne, primary, Pierik, Harm Jan, additional, van Dijk, Wout M., additional, van de Lageweg, Wietse I., additional, Brückner, Muriel Z. M., additional, van der Meulen, Bas, additional, and Kleinhans, Maarten G., additional
- Published
- 2022
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4. Experimental distributive fluvial systems: Bridging the gap between river and rock record
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Terwisscha van Scheltinga, Renske C., McMahon, William J., van Dijk, Wout M., Eggenhuisen, Joris T., Kleinhans, Maarten G., Biogeomorphology of Rivers and Estuaries, Sedimentology, Coastal dynamics, Fluvial systems and Global change, Biogeomorphology of Rivers and Estuaries, Sedimentology, and Coastal dynamics, Fluvial systems and Global change
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floodplain ,010504 meteorology & atmospheric sciences ,Floodplain ,Stratigraphy ,Fluvial system ,morphodynamics ,Environmental Science (miscellaneous) ,010502 geochemistry & geophysics ,Geologic record ,channels ,Oceanography ,01 natural sciences ,Bridging (programming) ,Geomorphology ,0105 earth and related environmental sciences ,geography ,geography.geographical_feature_category ,Palaeontology ,lcsh:QE1-996.5 ,Paleontology ,facies criteria ,Geology ,15. Life on land ,lcsh:Geology ,Distributive property ,avulsion ,stratigraphic record ,Beach morphodynamics - Abstract
A debate has called into question as to which fluvial channel patterns are most widely represented in the stratigraphic record, with some advocating that distributive fluvial systems (DFS) predominate and others that a broad diversity of fluvial styles may become preserved. Critical to both sides is the adequate recognition of original channel planform from geological outcrops separated from their formative processes by millions or even billions of years. In this study the river and rock record are linked through experimentally created DFSs with both aggrading channel beds and floodplains. This approach allows depositing processes and deposited strata to be studied in tandem. Proximal areas comprise coarse, amalgamated channel‐fills with scarce fine‐grained floodplain material. The overall spread of sandbody dimensions become far more varied in medial stretches, with an overall reduction in mean width and depth. In these areas channel‐fills may be sand‐rich or mud‐rich and, following avulsion, all channels are covered by floodplain sediment. Channels, levees and splays form discrete depositional bodies each with varying aspect ratios; a novel breadth of deposits and morphologies in aggrading experiments largely concurrent with proposed trends indicative of DFSs. The proportion of floodplain material increases distally, resulting in decreased interconnectedness of distal channel‐fills. Muddy floodplain sediments significantly change DFSs behaviour and subsequent stratigraphic architecture by enhancing bank stability and reducing avulsion through the filling of floodbasins. The laboratory methods utilised here open up the possibility of controlled experimentation on the effects and mechanisms of DFSs sedimentation, which is important since the modelled stratigraphic trends are rarely so tractable in ancient geological outcrop belts.
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- 2020
5. Geometry and topology of estuary and braided river channel networks automatically extracted from topographic data
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Hiatt, Matthew, Sonke, Willem, Addink, Elisabeth A., van Dijk, Wout M., van Kreveld, Marc, Ophelders, Tim, Verbeek, Kevin, Vlaming, Joyce, Speckmann, Bettina, Kleinhans, Maarten G., Landdegradatie en aardobservatie, Landscape functioning, Geocomputation and Hydrology, Biogeomorphology of Rivers and Estuaries, Sub Geometric Computing, Coastal dynamics, Fluvial systems and Global change, Applied Geometric Algorithms, Algorithms, Geometry and Applications, EAISI Foundational, EAISI Health, Landdegradatie en aardobservatie, Landscape functioning, Geocomputation and Hydrology, Biogeomorphology of Rivers and Estuaries, Sub Geometric Computing, and Coastal dynamics, Fluvial systems and Global change
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Estuarine and Nearshore Processes ,braided rivers ,Geometry ,EarthArXiv|Physical Sciences and Mathematics|Earth Sciences ,Oceanography ,Biogeosciences ,estuarine geomorphology ,01 natural sciences ,EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Geomorphology ,Earth and Planetary Sciences (miscellaneous) ,Digital elevation model ,network analysis ,Research Articles ,Water Science and Technology ,Geomorphology: General ,Estuarine Processes ,Ecology ,Palaeontology ,EarthArXiv|Physical Sciences and Mathematics|Computer Sciences ,Coastal Processes ,Forestry ,Oceanography: General ,Geophysics ,Geomorphology: Fluvial ,Metric (mathematics) ,Geomorphology and Weathering ,channel network extraction ,Geology ,Communication channel ,Network analysis ,Research Article ,bepress|Physical Sciences and Mathematics ,Scale (ratio) ,bepress|Physical Sciences and Mathematics|Earth Sciences|Geomorphology ,bepress|Physical Sciences and Mathematics|Earth Sciences ,Soil Science ,Topology (electrical circuits) ,Aquatic Science ,Stability (probability) ,Physics::Geophysics ,Geochemistry and Petrology ,fluvial geomorphology ,Global Change ,0105 earth and related environmental sciences ,Earth-Surface Processes ,bepress|Physical Sciences and Mathematics|Computer Sciences ,Channelized ,estuaries ,EarthArXiv|Physical Sciences and Mathematics ,Space and Planetary Science ,Hydrology - Abstract
Automatic extraction of channel networks from topography in systems with multiple interconnected channels, like braided rivers and estuaries, remains a major challenge in hydrology and geomorphology. Representing channelized systems as networks provides a mathematical framework for analyzing transport and geomorphology. In this paper, we introduce a mathematically rigorous methodology and software for extracting channel network topology and geometry from digital elevation models (DEMs) and analyze such channel networks in estuaries and braided rivers. Channels are represented as network links, while channel confluences and bifurcations are represented as network nodes. We analyze and compare DEMs from the field and those generated by numerical modeling. We use a metric called the volume parameter that characterizes the volume of deposited material separating channels to quantify the volume of reworkable sediment deposited between links, which is a measure for the spatial scale associated with each network link. Scale asymmetry is observed in most links downstream of bifurcations, indicating geometric asymmetry and bifurcation stability. The length of links relative to system size scales with volume parameter value to the power of 0.24–0.35, while the number of links decreases and does not exhibit power law behavior. Link depth distributions indicate that the estuaries studied tend to organize around a deep main channel that exists at the largest scale while braided rivers have channel depths that are more evenly distributed across scales. The methods and results presented establish a benchmark for quantifying the topology and geometry of multichannel networks from DEMs with a new automatic extraction tool., Key Points A new volume‐based method enables extraction of multithread channel networks from bathymetry across bed level jumpsBoth network topology and geomorphic information can be extracted at a range of spatial scalesEstuaries typically form a single dominant channel at the largest spatial scale, while braided rivers show no scaling break
- Published
- 2020
6. Complementing scale experiments of rivers and estuaries with numerically modelled hydrodynamics
- Author
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Weisscher, Steven A. H., primary, Boechat-Albernaz, Marcio, additional, Leuven, Jasper R. F. W., additional, Van Dijk, Wout M., additional, Shimizu, Yasuyuki, additional, and Kleinhans, Maarten G., additional
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- 2020
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7. Archimetrics: a quantitative tool to predict three‐dimensional meander belt sandbody heterogeneity
- Author
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van de Lageweg, Wietse I., van Dijk, Wout M., Box, Darren, Kleinhans, Maarten G., Sub AW Personeel 3e geldstroom, Biogeomorphology of Rivers and Estuaries, and Coastal dynamics, Fluvial systems and Global change
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010504 meteorology & atmospheric sciences ,Bar (music) ,preservation ,Stratigraphy ,Fluvial ,Environmental Science (miscellaneous) ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Flume experiment ,meandering river ,Sedimentology ,Geomorphology ,0105 earth and related environmental sciences ,sandbody heterogeneity ,Paleontology ,fluvial architecture ,Geology ,Point bar ,15. Life on land ,Flume ,morphodynamic modelling ,Spatial ecology ,Meander ,meander belt - Abstract
Fluvial meander belt sediments form some of the most architecturally complex reservoirs in hydrocarbon fields due to multiple scales of heterogeneity inherent in their deposition. Currently, characterization of meander belt bodies largely relies on idealized vertical profiles and a limited number of analogue models that naively infer architecture from active river dimensions. Three-dimensional architectural data are needed to quantify scales of grain-size heterogeneity, spatial patterns of sedimentation and bar preservation in a direct relationship with the relevant length scales of active river channels. In this study, three large flume experiments and a numerical model were used to characterize and construct the architecture (referred to as ‘archimetrics’) and sedimentology of meander belt deposits, while taking reworking and partial preservation into account. Meander belt sandbody width-to-thickness ratios between 100 and 200 were observed, which are consistent with reported values of natural meander belts. For the first time, the relief of the base of a meander belt is quantified, enabling improved estimates of connectedness of amalgamated meander belts. A key observation is that the slope and number of lateral-accretion packages within natural point bar deposits can be well predicted from fairly basic observables, a finding subsequently tested on several natural systems. Probability curves of preserved architectural characteristics for three dimensions were quantified allowing estimates of bar dimensions, baffle and barrier spacing distributions and container dimensions. Based on this, a set of rules were identified for combining reservoir parameters with the identified probability curves on sandbody dimensions and character, to help create more realistic geomodels for estimating exploration success on the basis of seismic and core data.
- Published
- 2016
8. Bifurcation instability and chute cutoff development in meandering gravel-bed rivers
- Author
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van Dijk, Wout M., primary, Schuurman, Filip, additional, van de Lageweg, Wietse I., additional, and Kleinhans, Maarten G., additional
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- 2014
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9. Bank pull or bar push: What drives scroll-bar formation in meandering rivers?
- Author
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van de Lageweg, Wietse I., primary, van Dijk, Wout M., additional, Baar, Anne W., additional, Rutten, Jantien, additional, and Kleinhans, Maarten G., additional
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- 2014
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10. Quantifiable effectiveness of experimental scaling of river- and delta morphodynamics and stratigraphy
- Author
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Kleinhans, Maarten G., van Dijk, Wout M., van de Lageweg, Wietse I., Hoyal, David C J D, Markies, Henk, van Maarseveen, Marcel, Roosendaal, Chris, van Weesep, Wendell, van Breemen, Dimitri, Hoendervoogt, Remko, Cheshier, Nathan, Coastal dynamics, Fluvial systems and Global change, Geomorfologie, Proceskunde, Bureau FG, Coastal dynamics, Fluvial systems and Global change, Geomorfologie, Proceskunde, and Bureau FG
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Length scale ,Scale (ratio) ,Stratigraphy ,Deltas ,Fluvial ,Earth and Planetary Sciences(all) ,Soil science ,Geomorphology ,Silt ,Scaling ,Experiments ,River patterns ,General Earth and Planetary Sciences ,Sediment transport ,Geology ,Beach morphodynamics ,Communication channel - Abstract
Laboratory experiments to simulate landscapes and stratigraphy often suffer from scale effects, because reducing length- and time scales leads to different behaviour of water and sediment. Classically, scaling proceeded from dimensional analysis of the equations of motion and sediment transport, and minor concessions, such as vertical length scale distortion, led to acceptable results. In the past decade many experiments were done that seriously violated these scaling rules, but nevertheless produced significant and insightful results that resemble the real world in quantifiable ways. Here we focus on self-formed fluvial channels and channel patterns in experiments. The objectives of this paper are 1) to identify what aspects of scaling considerations are most important for experiments that simulate morphodynamics and stratigraphy of rivers and deltas, 2) to establish a design strategy for experiments based on a combination of relaxed classical scale rules, theory of bars and meanders, and small-scale experiments focussed at specific processes. We present a number of small laboratory setups and protocols that we use to rapidly quantify erosional and depositional types of forms and dynamics that develop in the landscape experiments as a function of detailed properties, such as effective material strength, and to assess potential scale effects. Most importantly, the width-to-depth ratio of channels determines the bar pattern and meandering tendency. The strength of floodplain material determines these channel dimensions, and theory predicts that laboratory rivers should have 1.5 times larger width-to-depth ratios for the same bar pattern. We show how floodplain formation can be controlled by adding silt-sized silicaflour, bentonite, Medicago sativa (alfalfa) or Partially Hydrolyzed PolyAcrylamide (a synthetic polymer) to poorly sorted sediment. The experiments demonstrate that there is a narrow range of conditions between no mobility of bed or banks, and too much mobility. The density of vegetation and the volume proportion of silt allow well-controllable channel dimensions whereas the polymer proved difficult to control. The theory, detailed methods of quantification, and experimental setups presented here show that the rivers and deltas created in the laboratory seem to behave as natural rivers when the experimental conditions adhere to the relaxed scaling rules identified herein, and that required types of fluvio-deltaic morphodynamics can be reproduced based on conditions and sediments selected on the basis of a series of small-scale experiments.
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- 2014
11. Reduced-complexity probabilistic reconstruction of alluvial aquifer stratigraphy, and application to sedimentary fans in northwestern India
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van Dijk, Wout M., Densmore, Alexander L., Sinha, Rajiv, Singh, Ajit, and Voller, Vaughan R.
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Aquifer-body connectivity ,Alluvial aquifers ,Fan system ,Water Science and Technology ,Numerical model - Abstract
Generating a realistic model of subsurface stratigraphy that fits data from multiple well locations is a well-established problem in the field of aquifer characterisation. This is particularly critical for the alluvial fan-hosted aquifers in northwestern India, as they have some of the highest rates of groundwater extraction in the world and spatially limited subsurface observations. The objective of this study is to develop a reduced-complexity model that generates probabilistic estimates of aquifer body occurrence within a sedimentary fan, based loosely on the northwestern Indian aquifer system. We propose a parsimonious, inverse-weighted random walk model that reconstructs potential channel belt pathways within a discrete depth range or slice by (i) connecting known aquifer locations with the fan apex, (ii) filling adjacent cells with non-aquifer material based on estimated channel-body dimensions, and (iii) random filling of the remaining cells until the model fraction of aquifer material is comparable to the bulk aquifer fraction observed from well data. Once filled, individual depth slices can be stacked to produce a three-dimensional representation of aquifer-body geometry, allowing informed inference and testable predictions about the configuration of aquifer units in the subsurface. A receiver operating characteristic (ROC) curve shows that the model performs better than fully random filling, both in matching the locations of aquifer material in the subsurface and in reconstructing the geometry of relict channel bodies preserved on the fan surface. The model differs from purely statistical-empirical approaches by incorporating some geomorphic knowledge of fluvial channel belt geometry within the fan system. In contrast to a fully process-based approach, the model is computationally fast and is easily refined as new subsurface data become available.
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12. Effect of dredging and disposal on tidal bifurcations and flow asymmetry.
- Author
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van Dijk, Wout M., Leuven, Jasper R.F.W., Martens, Pauline S., Vlaming, Joyce, and Kleinhans, Maarten G.
- Subjects
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TSUNAMIS , *TIDAL flats , *CHANNEL flow , *SURFACE of the earth , *DREDGING , *HARBORS - Abstract
Estuaries are characterized by intertidal bars, i.e. shoals, that are encompassed by ebb and flood channels. Division of the flow at channel junctions into the ebb and flood channels indicates that the estuary consists of bifurcations that become confluences when flow reverts. While disturbances, such as shoal margin collapses (Van Dijk et al., 2019) only have a near-field effect on erosion and deposition at individual channel scale, the disturbance has a far-field effect on elevation jumps and flow division at the channel junctions. Because tidal asymmetry, produced by the distortion of the propagating tidal wave, is observed, we expect that a disturbance will migrate differently through the flood- and ebb-dominated channels. Our aim is to determine if we can approximate tidal bifurcations as river bifurcations, and quantify how dredging and disposal affect the channel network and bifurcation asymmetry at channel junctions. Therefore, we analysed bathymetry of the Western Scheldt (The Netherlands) since 1955 and used a Delft3D schematization of the Western Scheldt to isolate the effect of dredging and disposal strategies. We applied a novel channel network extraction tool, to determine changes in the bifurcation asymmetry and tidal asymmetry between the main, side and connecting channel scales.The tidal asymmetry in the Western Scheldt, represented by peak velocity ratio and period of flood-ebb ratio, shows that generally, the duration of the ebb flow is longer, whereas the flow current is stronger. Model results indicate that the bifurcation asymmetry is hardly affected by dredging. Tidal asymmetry changes depending on the disposal locations. The ebb period becomes longer and stronger at bifurcations in case dredged sediment is disposed of in the side channels. Dredging of the main channel leads to an increased elevation jump between the high-order channel and the bifurcating channel. We expected that the bifurcating channels would close off because the increase in elevation jump, however, both channels remains open because the increase in gradient is opposed by an increase in sinuosity, indicated by the bifurcation angle between the ebb and flood channels. Bifurcations become less stable in the case of dredging, which is indicated by the decrease in the number of bifurcations and the decrease in the number of ebb and flood channels in the channel networks.We conclude that tidal bifurcations, described by a bifurcation angle and elevation jump, can be approximated as river bifurcations. While dredging and disposal affect the stability of bifurcations by increasing the ebb period and decreasing the peak velocity ratio. The stability of bifurcations is important as it determines the number of connecting channels and the continuation of the multi-channel system, which affects the area of tidal flat and biodiversity in the Western Scheldt.Van Dijk, W.M., Hiatt, M.R. Van der Werf, J.J. and Kleinhans, M.G. (2019), Effects of shoal margin collapses on the morphodynamics of a sandy estuary. Journal of Geophysical Research – Earth Surface. [ABSTRACT FROM AUTHOR]
- Published
- 2019
13. Empirical Assessment Tool for Bathymetry, Flow Velocity and Salinity in Estuaries Based on Tidal Amplitude and Remotely-Sensed Imagery.
- Author
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Leuven, Jasper R. F. W., Verhoeve, Steye L., van Dijk, Wout M., Selaković, Sanja, and Kleinhans, Maarten G.
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BATHYMETRY ,FLOW velocity ,FLUID dynamics ,ESTUARIES ,REMOTE sensing ,INTERTIDAL ecology - Abstract
Hydromorphological data for many estuaries worldwide is scarce and usually limited to offshore tidal amplitude and remotely-sensed imagery. In many projects, information about morphology and intertidal area is needed to assess the effects of human interventions and rising sea-level on the natural depth distribution and on changing habitats. Habitat area depends on the spatial pattern of intertidal area, inundation time, peak flow velocities and salinity. While numerical models can reproduce these spatial patterns fairly well, their data need and computational costs are high and for each case a new model must be developed. Here, we present a Python tool that includes a comprehensive set of relations that predicts the hydrodynamics, bed elevation and the patterns of channels and bars in mere seconds. Predictions are based on a combination of empirical relations derived from natural estuaries, including a novel predictor for cross-sectional depth distributions, which is dependent on the along-channel width profile. Flow velocity, an important habitat characteristic, is calculated with a new correlation between depth below high water level and peak tidal flow velocity, which was based on spatial numerical modelling. Salinity is calculated from estuarine geometry and flow conditions. The tool only requires an along-channel width profile and tidal amplitude, making it useful for quick assessments, for example of potential habitat in ecology, when only remotely-sensed imagery is available. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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