Journal articles: 'River bar'

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Crosato, Alessandra, and Erik Mosselman. "An Integrated Review of River Bars for Engineering, Management and Transdisciplinary Research." Water 12, no. 2 (February 21, 2020): 596. http://dx.doi.org/10.3390/w12020596.

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River training and river restoration often imply modifying the patterns and dimensions of bars, channels, and pools. Research since the 1980s has greatly advanced and matured our knowledge on the formation and behavior of river bars, thanks to field work, laboratory experiments, theoretical analyses, and numerical modelling by several research groups. However, this knowledge is not easily accessible to design engineers, river managers, and ecologists who need to apply it. This is mainly due to confusing differences in terminology as well as to difficult mathematical theories. Moreover, existing scientific publications generally focus on specific aspects, so an overall review of the findings and their applications is still lacking. In many cases, the knowledge achieved so far would allow minimizing hard engineering interventions and thus obtaining more natural rivers. We present an integrated review of the major findings of river bar studies. Our aim is to provide accessible state-of-the-art knowledge for nature-based bar management and successful river training and river restoration. To this end we review the results from analytical, numerical, experimental, and field studies, explain the background of bar theories, and discuss applications in river engineering and river restoration.

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Jourdain, Camille, Nicolas Claude, Germain Antoine, Pablo Tassi, and Florian Cordier. "Influence of flood regime on riparian vegetation dynamics in rivers with alternate bars." E3S Web of Conferences 40 (2018): 02025. http://dx.doi.org/10.1051/e3sconf/20184002025.

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Throughout the 20th century, many rivers worldwide have undergone important riparian vegetation encroachment, which can be problematic in terms of flood risks and biodiversity. Nowadays, controlled floods is often considered as a management option in anthropized rivers, with the aim of limiting vegetation encroachment within river channels, as well as maintaining a diverse habitat by reactivating natural channel dynamics. In this context, this study aims at investigating the influence of different flood regimes on river bar vegetation development and dynamics, focussing on alternate bar systems which are typically found in embanked streams. This question has been addressed through two-dimensional bio-morphodynamic modeling of a simplified gravel bed river reach. Four hydrological scenarios with different flood peak discharges have been run for 50 years. For all scenarios, a steady increase in vegetation cover strongly impacts the evolution of bar morphology, until a relatively stable equilibrium is reached after one to three decades. Numerical results suggest that vegetation development on bars is associated to an increase in bar wavelength and a decrease in bar width. Higher peak flood discharges lead to narrower and longer bars, and a longer adjustment duration. When vegetation cover is fully developed, interannual flood variability seems crucial to maintain bedform and vegetation turnover.

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Pang, Xueqian, Cheng Xue, Yangping Liu, Li Yin, Yufeng Gao, and Yanshu Yin. "The Identification and Reservoir Architecture Characterization of Wandering Braided River in Nanpu 1-29 Area, Bohai Bay Basin." Geofluids 2022 (July 21, 2022): 1–17. http://dx.doi.org/10.1155/2022/4822714.

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Nanpu 1-29 Area of Jidong Oilfield in China is currently in the stage of high water cut and low recovery degree. The remaining oil development and adjustment are difficult because of the complex reservoir heterogeneity and the lack of analysis of the reservoir architecture due to the unclear river type. This study first used sedimentary background, granularity, core, and sand body distribution to determine the river type and believed it belongs to the wandering braided river. Combined with core and logging data, four types of sedimentary architectural elements were found in the study area, namely, channel bar, braided channel, floodplain, and basalt. Based on the scale measurement of many similar modern wandering braided rivers, core data, and empirical formulas, the scales of the braided rivers were determined. The quantitative relationships among the scale of the braided river, the channel bar, and the braided channel were established. With this constraint, the reservoir architecture was anatomized. The results showed two filling types of the braided channels, including sandy filling and muddy filling. The combination patterns of the channel bars and the braided channels could be divided into three types, namely, superimposed, standalone, and contact, and the contact type was the primary type. On the whole, it showed the geometric morphological characteristics of the flat top convex at the bottom of the channel bar and the flat bottom convex at the top of the braided river channel. A careful measure of the architectural element was executed. The length of the single braided flow belts was 365.16-1349.72 m, and the width was 270.57-1160.54 m. The channel bar’s length was distributed 158.89-318.32 m, and the width was distributed 75.97-116.41 m. The braided river’s width was distributed 16.81-180.05 m. The length and width ratio of the channel bar was concentrated between 2 and 4, which manifested wide bar and narrow river channel mode. Finally, the static distribution model and dynamic response curve were compared to verify the correctness of the reservoir architecture characteristics to guide the subsequent development of the oilfield.

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Wang, Jun, Shao Hua Li, Fu Lun Shi, and Xiao Ling Hu. "Development Mode of Delta Mouth Bar." Advanced Materials Research 807-809 (September 2013): 1620–23. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.1620.

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Es2 8th sand group in Shengtuo oilfield is a typical braided river delta front deposition. Through depositional physical simulation, the development mode of mouth bar and its main controlling factors were summarized. Physical model and experiment scheme were set up according to similarity criterion and the depositional background in research area. One provenance and three times simulation was designed to simulate three single layers within Es2 8th sand group respectively. Development mode of mouth bar was summarized with three single mouth bars based on swing conditions of rivel estuary and two composite mouth bars according to whether they are developed at the same time.

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Chaiwongsaen, Nikhom, Parisa Nimnate, and Montri Choowong. "Morphological Changes of the Lower Ping and Chao Phraya Rivers, North and Central Thailand: Flood and Coastal Equilibrium Analyses." Open Geosciences 11, no. 1 (April 9, 2019): 152–71. http://dx.doi.org/10.1515/geo-2019-0013.

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Abstract The Chao Phraya River flows in the largest river basin of Thailand and represents one of the important agricultural and industrial areas in Southeast Asia. The Ping River is one major upstream branch flowing down slope southwardly, joining the Chao Phraya River in the low-lying central plain and ending its course at the Gulf of Thailand. Surprisingly, the overflow occurs frequently and rapidly at the Lower Ping River where channel slope is high, and in particular area, sand-choked is extensively observed, even in normal rainfall condition. In contrary, at the downstream part, the erosion of river bank and shoreline around the mouth of Chao Phraya River has been spatially increasing in place where there should be a massive sediment supply to form a delta. Here we use Landsat imageries taken in 1987, 1997, 2007 and 2017 to analyze geomorphological changes of rivers. Results show that both rivers have undergone the rapid decreasing of water storage capacity and increasing of sand bar areas in river embayment. The total emerged sand bar area in the Lower Ping River increases from 1987 to 2017 up to 28.8 km2. The excessive trapped bed sediments deposition along the upper reaches is responsible for the shallower of river embankment leading to rapid overflow during flooding. At the Chao Phraya River mouth, a total of 18.8 km2 of the coastal area has been eroded from 1987 to 2017.This is caused by the reducing of sediment supply leading to non-equilibrium in the deltaic zone of the upper Gulf of Thailand. There are several possibility implications from this study involving construction of weir, in-channel sand mining, reservoir sedimentation and coastal erosion management.

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Yuskar, Yuniarti, and Tiggi Choanji. "Uniqueness Deposit of Sediment on Floodplain Resulting From Lateral Accretion on Tropical Area." Journal of Geoscience, Engineering, Environment, and Technology 2, no. 1 (March 1, 2017): 14. http://dx.doi.org/10.24273/jgeet.2017.2.1.12.

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Kampar rivers has a length of 413 km with average depth of 7.7 m and width of 143 m. Sixty percent of this rivers are meandering fluvial system which transport and deposit a mixture of suspended and bed-load (mixed load) along low energy. River channel that moving sideways by erosion is undergoing lateral migration and the top of the point bar becomes the edge of the floodplain and the fining-upward succession of the point bar will be capped by overbank deposits of Kampar River. Along the Kampar Rivers, there are more than 60% of ﬂoodplain sediments and almost all of the ﬂoodplain formed by bend migration on the suspended-load channels of Kampar watershed. This formation consist of succession of fine to medium sand and silt/mud, with root traces, that form as drapes on the prograding bank. These beds dip mostly channel wards and quickly wedge out as they grade up and onto the ﬂoodplain. The depositional model is presented showing how lateral accretion can make a signiﬁcant contribution to the preservation of ﬁne-grained within channel deposits in contemporary ﬂoodplains. The examples presented here demonstrate that analogues to ancient point-bar deposits containing alternating sandstone and shale sequences are common in the low-energy ﬂuvial environments of Riau rivers especially Kampar rivers.

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Shan, Xin, Xuefa Shi, Peter D. Clift, Ashraf Ali Seddique, Shengfa Liu, Chengpeng Tan, Jianguo Liu, Rased Hasan, Jingrui Li, and Zhaojun Song. "Sedimentology of the modern seasonal lower Ganges River with low inter-annual peak discharge variance, Bangladesh." Journal of the Geological Society 178, no. 1 (October 9, 2020): jgs2020–094. http://dx.doi.org/10.1144/jgs2020-094.

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The Ganges River, one of the largest rivers on Earth, is a typical monsoonal and flood-controlled system but has low inter-annual peak discharge variability. The seasonal discharge can reach 70 000 m3 s−1 during the wet season but maintains a low base flow of 500–3000 m3 s−1 during the dry season. However, the constancy in peak discharge every year categorizes the lower Ganges River as a river with low inter-annual peak discharge variability. This paper examines the modern lower Ganges River by conducting a detailed process-oriented investigation of the main channel, channel margin and overbank deposits, supplemented by satellite image observation and comparison with other modern fluvial systems. The channel and braid bar deposits show a dominance of small-scale to medium-scale cross-sets, with a variety of accretion processes constructing braid bars. The braid bar and channel deposits are typical of facies models of rivers with low inter-annual peak discharge variance. In contrast, the channel flank deposits are dominated by planar lamination, massive sand and mud couplets, and some ripple cross-lamination, with very little cross-bedding. Characteristic channel margin deposits represent sediments that accumulated by high-speed flows, multiple-surge and rapidly depositing flows, rapid or regular waning flows and hyperconcentrated flows. The overbank deposits predominantly comprise current ripples with long, thin bedforms and soft sediment deformation structures, which record flow transformation on the muddy flat topography and the processes of an unstable river bank. Our study shows that the channel margin and floodplain deposits are entirely different from those of the braid bar and channel. The bedform distribution of the fluvial deposits here (main channel, channel margin and overbank) may be an important tool in the identification of similar seasonal rivers with low inter-annual peak discharge variance and in the interpretation of fluvial processes.Supplementary material: The sediment texture and the depositional age is available at: https://doi.org/10.6084/m9.figshare.c.5144403

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Hashimoto, Kana, Takenori Shimozono, Yoshinao Matsuba, and Takumi Okabe. "Unmanned Aerial Vehicle Depth Inversion to Monitor River-Mouth Bar Dynamics." Remote Sensing 13, no. 3 (January 25, 2021): 412. http://dx.doi.org/10.3390/rs13030412.

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Monitoring the morphological evolution of a river-mouth bar is of both practical and scientific importance. A large amount of sediment is transported from a river to surrounding littoral cells via a deltaic bar after an extreme weather event. However, it is often not feasible to capture drastic morphological changes in the short term with conventional bathymetric surveys. This paper presents a depth-inversion method based on unmanned aerial vehicle technology to estimate two-dimensional bathymetry from video-sensed swell propagation. The estimation algorithm is tested over four cases with varying wave and bathymetric conditions and is validated with transect survey data. The test results suggest that the method can estimate deltaic-bar topography in front of a river mouth with a root-mean-square error of <0.5 m. The applicable range is limited by wave breaking in the inner bar and up to a depth of ~8 m, where swell intensity signals become ambiguous. A comparison of the different cases shows that the method works better under calm weather conditions with dominant swells propagating from non-local sources. Significant morphological changes of a river-mouth bar due to a powerful typhoon are successfully detected by observations right before and after the event.

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Kolozsvári, István, József Molnár, and György Dévai. "Recent river channel change detections in the section of the River Tisza above Tiszaújlak (BИЛОК)." Landscape & Environment 10, no. 3-4 (August 31, 2016): 123–30. http://dx.doi.org/10.21120/le/10/3-4/4.

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In the section above Tiszaújlak, despite the presence of embankments, the River Tisza shows active meandering tendency and it splits into branches resulting in side channels, dead channels and backwaters that follow the main channel. In our work we examined the right- and the left-side riverbank sections of the River Tisza, between Tiszaújlak (Вилок) and Tiszasásvár (Тросник), as well as between Tiszaújlak and Tiszapéterfalva (Пийтерфолво), to reveal the extent of bar depositions between 2006 and 2015, and to what extent the intensity and direction of the riverbank formation processes were influenced by the material of the bank and the plant coverage, its rate and characteristics. We tried to reveal which sections were eroded by the river and what security risks they have for the safety of the settlements along the Tisza River. On the right side of the Tisza River riverbank 51, and on the left side 62 main measuring points were recorded by GPS positioning satellite in 2009, 2010 and 2015. Our results were compared to the satellite images of Google Earth taken in 2006, too. According to our experience, in several bends of the examined sections of the river, active bar deposition can be observed; in some cases more than 100 m of bar depositions were detected.

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Wang, Zhaoyang, Hui Li, and Xiaobin Cai. "Remotely Sensed Analysis of Channel Bar Morphodynamics in the Middle Yangtze River in Response to a Major Monsoon Flood in 2002." Remote Sensing 10, no. 8 (July 24, 2018): 1165. http://dx.doi.org/10.3390/rs10081165.

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Channel bars are a major depositional feature in channels, and are considered as an important part of the morphodynamics of an alluvial river. The long-term morphodynamics of bars have been intensively investigated. However, relatively little is known about the response of channel bars to a major river flood, which is considered to be the predominant force in shaping bar morphology. This is especially the case for the monsoon-affected Yangtze River, where fluvial geomorphic work is largely carried out during monsoon floods. In this study, multi-temporal satellite images and river stage data were used to examine the morphodynamics of four large channel bars in the middle Yangtze River in response to a major monsoon flood in 2002. Based on bar surface areas estimated with Landsat images at different river stages, a rating curve was developed for each of the four bars, which was used to estimate bar volume through an integral process. Our study shows that two of the bars tended to be stable, while the other two experienced severe erosion during the flood. The results reveal that the flood caused a total bar surface area decrease of 1,655,100 m2 (or 8.30%), and a total bar volume decline of 5.89 × 106 m3 (or 6.10%) between the river stages of 20.81 m and 25.75 m. The volume decrease is equivalent to a sediment loss of approximately 8.25 × 106 metric tons, based on an average bulk density of 1.4 metric tons per cubic meter. The results imply that channel bars in the middle Yangtze River can also be large sediment sources rather than depositional areas during the flood. The decrease of sediment load in the middle of Yangtze River was found to be responsible for the dramatic morphodynamics of channel bars, which could last for a long period of time, depending on the operation of the Three Gorges Dam, which opened in 2003. Hence, we suggest making management efforts to protect the bars from further erosion.

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YAMAMOTO, Junya, Makoto NAKAMICHI, Masaaki HASHIMOTO, Jun KANETO, Tomokazu HIROSAWA, Takahiro NAKATSUJI, and Tomoaki TSUMURA. "MORPHOLOGICAL CHANGES OF THE RIVER MOUTH SAND BAR AT THE KUMANO RIVER." Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 77, no. 2 (2021): I_523—I_528. http://dx.doi.org/10.2208/kaigan.77.2_i_523.

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Zang, Dongsheng, Zhidong Bao, Mingyi Li, Ping Fu, Min Li, Bo Niu, Zhuolun Li, et al. "Sandbody architecture analysis of braided river reservoirs and their significance for remaining oil distribution: A case study based on a new outcrop in the Songliao Basin, Northeast China." Energy Exploration & Exploitation 38, no. 6 (August 27, 2020): 2231–51. http://dx.doi.org/10.1177/0144598720951280.

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The reservoir architecture analysis of braided rivers, especially falling-silt seam forms, has played a key role in predicting remaining oil distributions. However, no studies have used architecture analyses that document braided river outcrops and researched the tapping of the few remaining oil distributions based on outcrops in the Songliao basin, northeast China. In this paper, the architecture characteristics and remaining oil distribution of braided river reservoirs are studied using a combination of an outcrop, modern deposition and subsurface well data. The new 8–13 m thick Lower Cretaceous Quantou Formation outcrop of the Songliao basin is a braided fluvial succession arranged in one large fining-upward cycle. Eight facies (Gt, St, Sm, Sh, Sp, Sw, Fl and Fm), four architecture elements (CH, DA, LV, and FF), and three orders of bounding surfaces (third-, fourth-, and fifth-order) are recognized. A new distribution pattern of falling-silt seams and a braided river architecture model are presented according to the analysis of the outcrop. In the mid-channel bar, the falling-silt seams thin from the mid-bar to the bar tail following the flow direction. Each falling-silt seam is oriented tangentially to the basal surface of the mid-channel bar, and the upper falling-silt seam extends farther than the lower one. In a Daqing Oilfield exploitation block in the Songliao basin, while channels and bars are the main reservoir units, they have different remaining oil distribution patterns. For bars, water injection wells located at the mid-bar, zonal injection technology, the drilling of horizontal wells, and proper well patterns are proposed. Fourth-order bounding surfaces, single braided channels, stacking patterns, and the lateral blocking of levees and floodplains are the key factors affecting the remaining oil distribution in channels.

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Cyples, Natasha N., Alessandro Ielpi, and Randy W. Dirszowsky. "Planform and stratigraphic signature of proximal braided streams: remote-sensing and ground-penetrating-radar analysis of the Kicking Horse River, Canadian Rocky Mountains." Journal of Sedimentary Research 90, no. 1 (January 31, 2020): 131–49. http://dx.doi.org/10.2110/jsr.2020.6.

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ABSTRACT Braided rivers have accumulated a dominant fraction of the terrestrial sedimentary record, and yet their morphodynamics in proximal intermountain reaches are still not fully documented—a shortcoming that hampers a full understanding of sediment fluxes and stratigraphic preservation in proximal-basin tracts. Located in the eastern Canadian Cordillera near the continental divide, the Kicking Horse River is an iconic stream that has served as a model for proximal-braided rivers since the 1970s. Legacy work on the river was based solely on ground observations of small, in-channel bars; here we integrate field data at the scale of individual bars to the entire channel belt with time-lapse remote sensing and ground-penetrating-radar (GPR) imaging, in order to produce a more sophisticated morphodynamic model for the river. Cyclical discharge fluctuations related to both diurnal and seasonal variations in melt-water influx control the planform evolution and corresponding stratigraphic signature of trunk channels, intermittently active anabranch channels, and both bank-attached and mid-channel bars. Three-dimensional GPR fence diagrams of compound-bar complexes are built based on the identification of distinct radar facies related to: i) accretion and migration of unit bars, ii) both downstream and lateral outbuilding of bar-slip foresets; iii) buildup of bedload sheets, iv) channel avulsion, and v) accretion of mounded bars around logs or outsized clasts. Trends observed downstream-ward include decreases in gradient and grain size decreases, trunk-channel shrinkage, intensified avulsion (with increase in abundance for anabranch channels), and a shift from high-relief to low-relief bar topography. The integration of ground sedimentology, time-lapse remote sensing, and GPR imaging demonstrates that proximal-braided streams such as the Kicking Horse River can be critically compared to larger systems located farther away from their source uplands despite obvious scale differences.

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Becker, Carl M., and Leland R. Johnson. "History at the Bar: Navigability Great Miami River." Journal of Transport History 12, no. 2 (September 1991): 148–68. http://dx.doi.org/10.1177/002252669101200205.

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Blondeaux, P., and G. Seminara. "A unified bar–bend theory of river meanders." Journal of Fluid Mechanics 157 (August 1985): 449–70. http://dx.doi.org/10.1017/s0022112085002440.

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A two-dimensional model of flow and bed topography in sinuous channels with erodible boundaries is developed and applied in order to investigate the mechanism of meander initiation. By reexamining the problem recently tackled by Ikeda, Parker & Sawai (1981), a previously undiscovered ‘resonance’ phenomenon is detected which occurs when the values of the relevant parameters fall within a neighbourhood of certain critical values. It is suggested that the above resonance controls the bend growth, and it is shown that it is connected in some sense with bar instability. In fact, by performing a linear stability analysis of flow in straight erodible channels, resonant flow in sinuous channels is shown to occur when curvature ‘forces’ a ‘natural’ solution represented by approximately steady perturbations of the alternate bar type. A comparison with experimental observations appears to support the idea that resonance is associated with meander formation.

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Hadas, O., B. Shteinman, and R. Pinkas. "Distribution of fecal coliforms in the Jordan river mouth originating from anthropogenic activities in the watershed." Water Science and Technology 42, no. 1-2 (July 1, 2000): 129–33. http://dx.doi.org/10.2166/wst.2000.0303.

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The main inflow to Lake Kinneret is the Jordan River. A spit and a bar characterize the area where it enters the lake. The main processes occurring at the entrance are mixing, sedimentation and dispersion of the sediments. In the present study an interdisciplinary biological, physical and chemical approach was applied in order to follow the distribution of bacteria and river alluvium at the mouth of the river and relate the observed distribution to attenuation in velocity along the jet stream. The results showed that the jet flow rapidly attenuates when the Jordan enters the lake. The strong gradient in salinity indicated rapid mixing near the inflow. The distribution of fecal coliforms and fluorescent tracers indicated that the maximal longitudinal gradient was at the bar. Thus, bacteria and fluorescent tracers can be used as indicators of the distribution of particles originating in the Jordan River and entering the lake. Most of the parameters studied were found to vary in accordance with attenuation of the flow velocity as the jet diverges and disintegrates. Sedimentation dominated from the entrance to the bar and beyond the bar mixing (dilution) processes dominated.

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Bywater-Reyes, Sharon, Rebecca M. Diehl, and Andrew C. Wilcox. "The influence of a vegetated bar on channel-bend flow dynamics." Earth Surface Dynamics 6, no. 2 (June 14, 2018): 487–503. http://dx.doi.org/10.5194/esurf-6-487-2018.

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Abstract. Point bars influence hydraulics, morphodynamics, and channel geometry in alluvial rivers. Woody riparian vegetation often establishes on point bars and may cause changes in channel-bend hydraulics as a function of vegetation density, morphology, and flow conditions. We used a two-dimensional hydraulic model that accounts for vegetation drag to predict how channel-bend hydraulics are affected by vegetation recruitment on a point bar in a gravel-bed river (Bitterroot River, Montana, United States). The calibrated model shows steep changes in flow hydraulics with vegetation compared to bare-bar conditions for flows greater than bankfull up to a 10-year flow (Q10), with limited additional changes thereafter. Vegetation morphology effects on hydraulics were more pronounced for sparse vegetation compared to dense vegetation. The main effects were (1) reduced flow velocities upstream of the bar, (2) flow steered away from the vegetation patch with up to a 30 % increase in thalweg velocity, and (3) a shift of the high-velocity core of flow toward the cut bank, creating a large cross-stream gradient in streamwise velocity. These modeled results are consistent with a feedback in channels whereby vegetation on point bars steers flow towards the opposite bank, potentially increasing bank erosion at the mid- and downstream ends of the bend while simultaneously increasing rates of bar accretion.

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Ning, Zhao, Gao Xia, Chen Zhongmin, Huang Jiangqin, and Zhang Guangya. "High Resolution Sequence Stratigraphy Correlation and Sedimentary Model of Braided Rivers: A Case on Paleogene Palogue Oilfield, South Sudan." E3S Web of Conferences 53 (2018): 03024. http://dx.doi.org/10.1051/e3sconf/20185303024.

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Complicated fluvial sands correlation and braided river models are still challenges for heterogeneous anisotropic reservoir evaluation for petroleum development in oilfields. Based on high-resolution sequence stratigraphy and sedimentology, core observation, and the analysis of logging and seismic data, high-resolution sequence stratigraphy framework of Paleogene Yabus formation of Palogue Oilfield, South Sudan is established, and sedimentary characteristics of braided rivers are analyzed, (1) In braided river deposits, channel bars are usually pro-gradating seawards and going thicker upwards. And braided channels are retro-gradating landwards and going thinner upwards. Both of them can be subdivided into channel (bar) trunks and channels (bar) flanks, showing vertical stacking and lateral migration; (3) As the A/S (Accommodation space/sediments supply) increasing upwards, braided river sands are shifting frequently as a reciprocating migration in Yabus V/VI, and they are more stable as the A/S decreasing upwards as a vertical aggradation in Yabus VII/VIII; (4) With 77 wells sedimentary microfacies identification, sand thickness and sand/bed ratio distribution, sedimentary facies distribution of all members and zones are analyzed. According to the A/S change, three braided river models are concluded, including isolated channel type (high A/S period), crossed channels type (medium A/S period), and superposed channels type (low A/S period).

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KATAYAMA, Takashi, Masamitsu KUROIWA, Shinji YAMAMOTO, Yuki KAJIKAWA, and Daichi TAJIMA. "A RIVER MOUTH BAR MORPHODYNAMICS DUE TO WAVES AND RIVER FLOODS AT TENJIN RIVER IN TOTTORI." Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 76, no. 2 (2020): I_613—I_618. http://dx.doi.org/10.2208/kaigan.76.2_i_613.

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Amissah, Gabriel Jonathan, Tímea Kiss, and Károly Fiala. "Active point bar development and river bank erosion in the incising channel of the lower Tisza river, Hungary." Landscape & Environment 13, no. 1 (December 20, 2019): 13–28. http://dx.doi.org/10.21120/le/13/1/2.

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The development of point-bars and bank erosion are critical near-bank processes, as they indicatethe sediment and hydraulic regime of a river system, thus, they refer to the equilibrium conditions ofa channel. However, throughout history, rivers have been modified for various benefits which changethe development of point-bars and the rate of bank erosion. In the Lower Tisza River (Hungary), riverregulations influenced the channel and floodplain development, altering the natural fluvial processes.The aim of the research was to determine the rate of near-bank processes and to make trajectory forfuture river evolution to support future engineering works. The bank erosion and point-bar developmentat human-influenced and freely meandering sections of the Tisza River were monitored since 2011.Behind a collapsed revetment, the bank erosion rate was 0.6 m/y, while at a freely meandering section itwas 2.3 m/y. The studied point-bars are located in revetted and freely meandering sections. Their surfaceeroded within the period. These intensive erosional processes refer to an incising meandering channel,which must be considered during future planning of in-channel structures (e.g. revetments, bridges),thus, geomorphic methods must be considered in any river engineering scheme.

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Liro, Maciej, and Kazimierz Krzemień. "Wpływ cofki zbiornika zaporowego na koryto rzeki górskiej – perspektywy badań = The impact of dam-reservoir backwater on mountain river channel – research perspectives." Przegląd Geograficzny 92, no. 1 (2020): 55–68. http://dx.doi.org/10.7163/przg.2020.1.4.

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Dam reservoir construction is one of the most important factors shaping river-valley morphology in the Anthropocene. While a large number (>58,000) of these constructions are in operation all over the world, we remain quite ignorant of what happens upstream of them (in so called backwater zone), especially for the case of gravel-bed rivers. Existing studies have shown that adjustments of the gravel-bed river in the backwater zone differ between the initial and long-term adjustments. The initial adjustments (occurring ≈ <20 years following dam construction) are controlled by large floods and in-channel deposition which trigger bi-directional bar↔bank interactions (bank erosion causing bar growth and vice versa) resulting in channel-widening. The long-term adjustments (≈ >20 years following dam construction) are characterized by river sinuosity increa sing and channel planform stabilization resulted from deposition of fine sediment and associated vegetation expansion. The long-term adjustments are controlled by the initial river morphology, which creates accommodation space for the deposition of fine sediment and for the associated expansion of vegetation on channel bars. The multi-thread river in backwater zone is significantly narrowed, its sinuosity increase (phase 1) and the planform is stabilized (phase 2). Whereas, in the case of initially single-thread river only planform stabilization occur (phase 2). This article summarizes recent findings on the backwater effects on gravel-bed channel morphodynamics, suggesting that backwater zones may be treated as hot-spots of human-induced changes in river geomorphology and biogeomorphology.

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OCHI, Takaharu, Keiichi KANDA, Hiroshi MIWA, Rinto KOSHI, and Fuminori NAKAMURA. "DYNAMIC STATE OF RIVER-MOUTH BAR AND ITS CONTROL IN THE YURAGAWA RIVER." Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 71, no. 4 (2015): I_907—I_912. http://dx.doi.org/10.2208/jscejhe.71.i_907.

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Zen, S., G. Zolezzi, and M. Tubino. "A theoretical analysis of river bars stability under changing channel width." Advances in Geosciences 39 (April 1, 2014): 27–35. http://dx.doi.org/10.5194/adgeo-39-27-2014.

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Abstract. In this paper we propose a new theoretical model to investigate the influence of temporal changes in channel width on river bar stability. This is achieved by performing a nonlinear stability analysis, which includes temporal width variations as a small-amplitude perturbation of the basic flow. In order to quantify width variability, channel width is related with the instantaneous discharge using existing empirical formulae proposed for channels with cohesionless banks. Therefore, width can vary (increase and/or decrease) either because it adapts to the temporally varying discharge or, if discharge is constant, through a relaxation relation describing widening of an initially overnarrow channel towards the equilibrium width. Unsteadiness related with changes in channel width is found to directly affect the instantaneous bar growth rate, depending on the conditions under which the widening process occurs. The governing mathematical system is solved by means of a two-parameters (ε, δ) perturbation expansion, where ε is related to bar amplitude and δ to the temporal width variability. In general width unsteadiness is predicted to play a destabilizing role on free bar stability, namely during the peak stage of a flood event in a laterally unconfined channel and invariably for overnarrow channels fed with steady discharge. In this latter case, width unsteadiness tends to shorten the most unstable bar wavelength compared to the case with constant width, in qualitative agreement with existing experimental observations.

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Iwasaki, Toshiki, Satomi Yamaguchi, and Hiroki Yabe. "Numerical simulation of bedload tracer transport associated with sand bar formation, bank erosion, and channel migration." E3S Web of Conferences 40 (2018): 02013. http://dx.doi.org/10.1051/e3sconf/20184002013.

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An understanding of bedload transport processes is an essential research goal for better prediction of river morphology and morphodynamics as well as the transport and fate of sediment-bound materials in river systems. Passive tracer particles have been used widely to monitor bedload transport processes in rivers by measuring the spatiotemporal distribution of the bedload tracers. Here, we propose a numerical model for reproducing the transport of bedload tracers in river systems, more specifically, the behaviours of bedload tracers under the influence of complex river morphodynamics. A two-dimensional morphodynamic model is combined with a flux-based bedload tracer model with use of the active layer approach. The model is applied to a laboratory experiment that demonstrates the transport processes within the channel of bedload tracers supplied from the floodplain. The numerical model effectively reproduces the main features of the experiment, namely, the bedload tracers supplied from the floodplain due to bank erosion deposit onto sand bars developed within the channel. Because the sand bars cause a very long residence time of the bedload tracers within the bed, the transport speed of the tracers is slowed significantly under the influence of bar formation and channel migration.

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Cordier, Florian, Pablo Tassi, Nicolas Claude, Alessandra Crosato, Stephane Rodrigues, and Damien Pham Van Bang. "Influence of hydrology, sediment supply and sediment gradation on river bar morphodynamics: application to the Loire River at Bréhémont (France)." E3S Web of Conferences 40 (2018): 02023. http://dx.doi.org/10.1051/e3sconf/20184002023.

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Rivers inherently show heterogeneous sediment sizes and can also show a strong sediment supply variability in time because of natural episodic events or as a consequence of human activities, which alter the characteristics and dynamics of alluvial bars at the macro-scale. The impact of the combination between sediment size heterogeneity and sediment supply variation, or even with other forcings (i.e. hydrology, channel geometry) remains poorly documented. In this work, a physics-based numerical model is applied on a trained reach of a sandy-gravel bed river to investigate the combination of these parameters on bar morphodynamics. The morphodynamic computations are performed with a two-dimensional depth-averaged hydrodynamic solver, internally coupled to a sediment transport and bed evolution module, which estimate the transport of graded sediment and model bed stratigraphy, respectively. A 1 km long reach of the Loire River at Bréhémont (France) is selected to conduct the numerical investigations. The interaction between several forcing mechanisms induces highly complex bar morphodynamic processes in this area.A comprehensive set of high-definition data is available, which allows to study the river morphodynamics for a succession of three flooding events and a period of low flows. Based on this model, a variety of scenarios is presented with the aim of exploring the implications of sediment gradation, geometrical and boundary forcing effects on in situ bars morphodynamics.

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Shukla, U. K., I. B. Singh, P. Srivastava, and D. S. Singh. "Paleocurrent patterns in braid-bar and point-bar deposits; examples from the Ganga River, India." Journal of Sedimentary Research 69, no. 5 (September 1, 1999): 992–1002. http://dx.doi.org/10.2110/jsr.69.992.

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27

Kim, Yeon-Joong, Joung-Woon Woo, Jong-Sung Yoon, and Myoung-Kyu Kim. "Development of a Numerical Model to Analyze the Formation and Development Process of River Mouth Bars." Journal of Korean Society of Coastal and Ocean Engineers 33, no. 6 (December 31, 2021): 308–20. http://dx.doi.org/10.9765/kscoe.2021.33.6.308.

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An integrated sediment management approach that includes the recovery of the amount of declined sediment supply is effective as a fundamental solution to coastal erosion. During planning, it is essential to analyze the transfer mechanism of the sediments generated from estuaries (the junction between a river and sea) to assess the amount and rate of sediment discharge (from the river to sea) supplied back to the coast. Although numerical models that interpret the tidal sand bar flushing process during flooding have been studied, thus far, there has been no study focusing on the formation and development processes of tidal sand bars. Therefore, this study aims to construct wave deformation, flow regime calculation, and topographic change analysis models to assess the amount of recovered sediment discharge and reproduce the tidal sand bar formation process through numerical analysis for integrated littoral drift management. The tidal sand bar formation process was simulated, and the wave energy and duration of action concepts were implemented to predict the long-term littoral movement. The river flux and wave conditions during winter when tidal sand bars dominantly develop were considered as the external force conditions required for calculation. The initial condition of the topographic data directly after the Maeupcheon tidal sand bar flushing during flooding was set as the initial topography. Consequently, the tidal sand bar formation and development due to nearshore currents dependent on the incident wave direction were reproduced. Approximately 66 h after the initial topography, a sand bar formation was observed at the Maengbang estuary.

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Md. Amir Khan and Nayan Sharma. "Turbulence Study Around Bar in a Braided River Model." Water Resources 46, no. 3 (May 2019): 353–66. http://dx.doi.org/10.1134/s0097807819030023.

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29

Richardson, W. Roy, and Colin R. Thorne. "Secondary Currents around Braid Bar in Brahmaputra River, Bangladesh." Journal of Hydraulic Engineering 124, no. 3 (March 1998): 325–28. http://dx.doi.org/10.1061/(asce)0733-9429(1998)124:3(325).

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ONO, Tomoki, Mikito TAKAHASHI, and Satoshi TAKEWAKA. "FLUSHING PROCESSES OF RIVER SAND BAR OBSERVED WITH X-BAND RADAR AT RIVER TENRYU." Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 72, no. 2 (2016): I_721—I_726. http://dx.doi.org/10.2208/kaigan.72.i_721.

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31

Yin, Shuran, Yunpig Yang, Jianjun Wang, Jie Zhang, Qinghua Cai, Yude Zhu, and Chenyang Wang. "Simulating Ecological Effects of a Waterway Project in the Middle Reaches of the Yangtze River Based on Hydraulic Indicators on the Spawning Habitats of Four Major Chinese Carp Species." Water 14, no. 14 (July 6, 2022): 2147. http://dx.doi.org/10.3390/w14142147.

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The adaptability of fish to their habitats is closely related to river hydraulics. While navigation channel projects aim to improve the navigation conditions by adjusting the hydrodynamic force of local river sections, the impacts of these projects on the hydraulic indicators of habitats of the four major Chinese carp species (FMCCs) remain unclear. Taking the Daijiazhou reach in the middle reaches of the Yangtze River as a case study, a mathematical model for spawning suitability was established to simulate changes in these hydraulic indicators before and after the implementation of a navigation channel project. The optimal flow rate interval for the spawning of the FMCCs was 17,500–22,000 m3·s−1. After the navigation channel project was implemented, the habitat suitability index (HSI) and weighted useable area (WUA) increased across the spawning habitats of all FMCCs, indicating that the project implementation created more habitat space. The central bar (Chihugang central bar) became exposed during the dry season, with the HSI and WUA decreasing under low water flow but increasing under medium-low or higher water flow levels. At the Daijiazhou bar head floodplain, which remained unexposed during the dry season, the HSI and WUA increased after project implementation, providing more space for spawning and habitation for the FMCCs. For the low point bar with bank gullies (Lejiawan point bar), the implementation of the bar protection zone project restricted gully development, with the HSI and WUA decreasing for all FMCCs. Based on the above impacts of navigation channel projects on the hydrodynamic environment of fish habitats, this paper provides a reference for the optimization of navigation channel arrangement as well as for the restoration of fish habitats.

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32

Purdešová, Andrea. "Determination of Selected Pesticide Residues in River Water Using SBSE Technique." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 65, no. 5 (2017): 1595–99. http://dx.doi.org/10.11118/actaun201765051595.

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The analytical procedure based on stir‑bar sorptive extraction technique, for the determination of selected pesticide residues (diazinon, malathion, cyprodinyl, penconazole, fludioxonyl, pyriproxyfen, boscalid, pyraclostrobin) is described. Analysis was performed using the commercial TwisterTM stir bar for sorptive extraction. It consists of a 2.0‑cm‑long glass‑encapsulated magnetic stir bar externally coated with PDMS. The extracts were off‑line analyzed using fast GC‑MS in SIM mode. Optimized conditions were established as follows concerning extraction time, stirring speed, aqueous medium characteristics (ionic strength and polarity) respectively: 120 min (700 rpm), addition of 4 g of sodium chloride, no addition of methanol as organic modifier, and 30 min ultrasonic desorption in acetonitrile. Recoveries ranged from 38 % to 58 % (RSD < 15 %, n = 6). Validated limits of quantification in matrix were between 1.6 ngL−1 and 548.8 ngL−1, depending on the compound.

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33

Dou, Mengjiao, Shaohua Li, Tao Lei, Guanglei Ren, Xiaohui Li, Ying Guo, Wenjie Feng, and Xianghui Zhang. "Hierarchical Multiple-Point Geostatistical Modeling Method and Application Based on Braided River Reservoir Architecture." Minerals 12, no. 11 (October 31, 2022): 1398. http://dx.doi.org/10.3390/min12111398.

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The Lower Shihezi Formation of the Daniudi gas field in the Ordos Basin is a typical reservoir of a braided river system in an alluvial plain, characterized by extensive braided river development, parallel development from the near source to the center of the basin, and frequent interweaving and cut stacking, as well as a complex deposition process that has seen frequent river channel changes. The braided river belt, braided channel, channel bar inside the river, and interlayer within the channel bar constitute a hierarchical and complicated architectural feature, which poses a great challenge to accurately characterize this type of reservoir for modeling. We proposed a hierarchical, level-by-level embedding, and progressive multiple-point geostatistical modeling strategy that is refined layer by layer according to a 5–3 level architectural unit hierarchy, with the modeling results of each level providing constraints for the next level modeling. The hierarchical geological model based on the combination of qualitative architectural anatomy and quantitative pre-architecture unit scale is critical in guiding the efficient development of the remaining gas in the braided river reservoir in Daniudi.

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Dai, Huang, Toshiki Iwasaki, and Yasuyuki Shimizu. "Effect of Sediment Supply on Morphodynamics of Free Alternate Bars: Insights from Hydrograph Boundary Layer." Water 13, no. 23 (December 4, 2021): 3437. http://dx.doi.org/10.3390/w13233437.

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Sediment supply plays an essential role in river morphology. However, the specific impact of sediment supply on river morphology is not apparent. According to the hydrograph boundary layer (HBL) concept, upstream riverbed changes caused by the imbalance between sediment supply and the capacity can propagate only a limited length and have a negligible effect on the riverbed beyond such a short length. We performed a two-dimensional morphodynamic calculation to test the concept of HBL, which was proposed under a one-dimensional simulation, meaning that the concept of HBL is still valid for plane changes in river morphology. We employed an unsteady flow with equilibrium or constant sediment supply in a straight, modeled gravel-bedded channel with an unerodible bank to simulate alternate bar morphodynamics. The results show that regardless of the sediment supply condition, the alternate bar features formed downstream of the HBL are considerably similar. This suggests that sediment disturbance at the upstream end has a negligible effect on the mobile-bed dynamic processes, including alternate bar formation and development downstream of the HBL.

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35

Thapliyal, Madhu, Bipin Kumar Sati, Ravi Kumar, Tribhuwan Chandra, and Ashish Thapliyal. "DNA barcoding of fishes from River Song, Dehradun, Uttarakhand using mitochondrial cytochrome-c oxidase-I gene." Environment Conservation Journal 14, no. 3 (December 21, 2013): 113–21. http://dx.doi.org/10.36953/ecj.2013.14320.

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The entire Himalayan region is well known as a global hotspot for biodiversity. Many workers have documented different aspect of biodiversity. The Uttarakhand Himalaya region, a part of Himalayan system, is very rich in fresh water aquatic biodiversity because it has many fresh water streams and rivers within a short distance of 200 miles. All these fresh water bodies harbor diverse aquatic fauna with fishes being the most extensively studied. There are many fish species reported by many authors in Uttarakhand. Many of the fishes have similar morphological characters (morpho-metrics) and are difficult to identify. Attempts have been made to generate the DNA barcode of fishes but most of the attempt are limited to major rivers i.e. the Ganges and the Yamuna. Besides these two prominent river (the Ganges & the Yamuna), there are many supporting streams and small tributaries that are also inhabited by many species. No “long term” and “entire river scan” for fish species has ever been conducted in Uttarakhand. Our research aims to generate a molecular database (DNA Barcode) for entire fish species fauna in each small river/stream of Uttarakhand. Using a combination of morphometric & DNA bar-coding data will provide an efficient method for species level identification and contributes considerably to taxonomic and biodiversity research. The present study is first step towards establishing molecular taxonomy database of Uttarakhand based upon the bar coding pattern of cytochrome c oxidase I (COI) gene. We carried out an “entire river scan” of River Song (a tributary of river Ganges). 50 samples were collected from various sampling sites along the entire stretch of river and analyzed. Data was uploaded into the BOLD database and the analysis of data using this database suggests that the genetic variability (K2P distance) distribution of 50 individuals belonging with 15 species.The average intraspecific variation using K2P and NJ methods/models was assessed. The mean intraspecific distance was less than 1.45% for 32% of species. Mean K2P distance within species, genus and family was 0.1%, 16.3% and 21.70% respectively. Our results suggest that River Song has diverse fish fauna with substantial genetic diversity. Data from Barillius species suggests that this species has a very high variation. There is ahighly probability that as all the rivers are scanned new data on endemic and exotic fish fauna diversity will emerge which would be helpful in conservation efforts.

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36

Haug, Jonas, Stefan Auer, Calvin Frees, Barbara Brinkmeier, Ruben Tutzer, Daniel S. Hayes, and Markus Aufleger. "Retrofitting of Existing Bar Racks with Electrodes for Fish Protection—An Experimental Study Assessing the Effectiveness for a Pilot Site." Water 14, no. 6 (March 9, 2022): 850. http://dx.doi.org/10.3390/w14060850.

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Downstream-migrating fish in rivers tend to follow the main current, and are in danger of swimming through the turbines at run-of-river hydropower plants, possibly causing high mortality rates. To avoid these losses, fish must be prevented from entering the turbines. Most existing vertical bar rack systems (used for turbine protection) however usually do not ensure proper fish protection due to large bar spacings. FishProtector technology enables the retrofitting of existing bar racks (i.e., the mechanical barrier) with additional electrodes to create a hybrid barrier. The induced electric field in the water aims to create a behavioral barrier to prevent fish passage through the bar rack. In this study, ethohydraulic experiments to investigate the effect of such a behavioral barrier on fish were performed. In detail, the fish-protection rate at a bar rack with a bar spacing of 30 mm was tested in five different scenarios: (i) a bar rack without electrodes (reference), and four electrified setups with electrode spacings of (ii) 80 mm, (iii) 120 mm, (iv) 160 mm, and (v) 200 mm. A flow velocity of 0.23 m/s was chosen to replicate the situation at a planned pilot site. The study was conducted in an outdoor laboratory flume using small fish of several local riverine species, mostly cyprinids and minnows. The results show that the mean fish-protection rate in the experiments could be increased from 62% in the reference setup up to 96% in the electrified setups.

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Cintra, Jorge Pimentel. "THE EXPLORATION OF THE TIETÊ RIVER BY THE COMISSÃO GEOGRÁFICA E GEOLÓGICA (1905): CARTOGRAPHIC ASPECTS." Boletim de Ciências Geodésicas 23, no. 2 (June 2017): 309–26. http://dx.doi.org/10.1590/s1982-21702017000200020.

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This paper studies the cartographic products associated with the Tiete River Exploration Report, (1905) published by the Geographical and Geological Committee of the São Paulo Province. The expedition, from the Bar of the Jacaré-Guassú River to the Paraná River, led to the mapping of the Tietê River, which, along with others, is part of the efforts made by this state agency so that there was no longer a great region called "Unknown hinterland inhabited by Indians" in the official map of the Province of Sao Paulo. The purpose was not only to map, but also to raise the mineral resources, the geology, focused on the types of soil and its agricultural potential, and the navigability of rivers for transporting people and goods. The data obtained are studied (altitudes, longitudes, magnetic declination), surveys paths, equipment used, work methodology and the Cartography produced: General Map, Partial Maps, Profile, Cross Sections and others.

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38

Glad, Aslaug C., Lars Ole Boldreel, Lars B. Clemmensen, and Mads E. Willumsen. "Meandering river deposits in sediment cores, the Middle Jurassic Alma Field, Southern Danish Central Graben." Bulletin of the Geological Society of Denmark 66 (September 26, 2018): 189–209. http://dx.doi.org/10.37570/bgsd-2018-66-10.

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Fluvial deposits are amongst the most important terrestrial hydrocarbon reservoirs, but the complex nature of these deposits is challenging in subsurface reservoir characterisation. This study is the first detailed facies analysis of the meandering river deposits of the Middle Jurassic Alma Field situated in the southern Danish North Sea. The fluvial sandstones and their associated deposits are described and interpreted based on studies from two core sites (Alma-1X and Alma-2X). The facies analysis of the cores demonstrates the presence of three meandering river facies associations: Channel deposits, channel margin deposits and floodplain deposits. The channel deposits comprise channel thalweg and point bar sediments, the channel margin deposits include crevasse channel and crevasse splay sediments, while the floodplain deposits comprise overbank and backswamp sediments. The point bar deposits are composed of fine- to medium-grained sandstones but can contain intervals of finer grained sediments, particularly in their upper parts where they can grade into muddy sandstones or true heterolithic deposits. Preserved sand body thicknesses (channel thalweg and point bar deposits) in both Alma cores have a mean value of 2.6 m and a maximum value of 4.35 m (Alma-1X) and 6.55 m (Alma-2X). Using maximum values of channel deposit thicknesses, and assuming the preservation conditions are met, the width of the largest ancient channel belt in Alma-1X would be between 90 m and 200 m or around 900 m, depending on whether the fluvial system is mud-rich or sand-rich. The same method applied to Alma-2X gives a width of the largest channel belt between 130 m and 330 m or around 1300 m. Fluvial sediments of the Middle Jurassic Scalby Formation (north-east England) were deposited in a sandy meandering river with sedimentary characteristics corresponding to those observed in the Alma cores. Outcrop analogue investigations of this formation were carried out to examine the architecture of the fluvial facies in a two-dimensional section with emphasis on channel thalweg and point bar deposits. Combined evidence from core analysis and outcrop analogue studies suggests that the fluvial deposits in the Alma Field represent a mixed-load meandering river system with sandy point bars. The meandering river system developed on a coastal plain with overbank fines and organic-rich backswamp deposits. The mud-rich or heterolithic deposits in the upper part of the point bar facies intervals are noteworthy and could indicate markedly fluctuating discharge in a mixed-load river.

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Zhang, Zili, Xiaomin Zhu, Qi Li, Ruifeng Zhang, Jing Zhang, and Yi Huang. "Depositional characteristics of fluvial facies in gentle slope zone of lacustrine rift basins: The third member of the Dongying Formation in the Wen’an Slope of Baxian Sag, Bohai Bay Basin, China." Interpretation 8, no. 2 (May 1, 2020): SF37—SF55. http://dx.doi.org/10.1190/int-2019-0125.1.

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We have integrated core, well logs, and seismic data to analyze fluvial types and reconstruct sediment dispersal patterns of the Dongying Formation in the Wen’an Slope, Bohai Bay Basin (China). We analyzed four meandering-braided fluvial successions from the Dongying Formation in the Wen’an Slope. The results indicate that the fluvial systems are dominantly northeast–southwest and consist of channel, channel bar, and flood plain subfacies, which can be further subdivided into six microfacies including braided channel, meandering channel, sandy channel bar, muddy channel bar, crevasse fan, and floodplain. With a paleoflow direction, [Formula: see text] ranges from 40° to 65°, the river belt width [Formula: see text] is estimated to be 1.47–2.64 km, whereas the main channel width varies from 0.02 to 0.29 km and its thickness/bankfull depth [Formula: see text] ranges from 1.2 to 6.4 m. The differential subsidence of rift basin during fault-depression transition period is the main control on fluvial evolution and sand body distribution. The climatic effect causes changes in river flow. During the flood season, river flow and flow rate are large, and early sediments and sand bodies are reconstructed. Lateral erosion and undercutting are very strong in this period. In the dry season, the river is dominated by weak lateral erosion. Our study also suggests that the development of thick mudstone in the upslope may limit hydrocarbon charging and migration and thick channel and channel bar deposits in the middle and downslope cross cut by faults, which are conduits for migration are likely to be the most potential reservoirs in the Bohai Bay Basin.

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Alexander, Jason S., Brandon J. McElroy, Snehalata Huzurbazar, and Marissa L. Murr. "Elevation gaps in fluvial sandbar deposition and their implications for paleodepth estimation." Geology 48, no. 7 (April 29, 2020): 718–22. http://dx.doi.org/10.1130/g47521.1.

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Abstract Accurate estimation of paleo–streamflow depth from outcrop is important for estimation of channel slopes, water discharges, sediment fluxes, and basin sizes of ancient river systems. Bar-scale inclined strata deposited from slipface avalanching on fluvial bar margins are assumed to be indicators of paleodepth insofar as their thickness approaches but does not exceed formative flow depths. We employed a unique, large data set from a prolonged bank-filling flood in the sandy, braided Missouri River (USA) to examine scaling between slipface height and measures of river depth during the flood. The analyses demonstrated that the most frequent slipface height observations underestimate study-reach mean flow depth at peak stage by a factor of 3, but maximum values are approximately equal to mean flow depth. At least 70% of the error is accounted for by the difference between slipface base elevation and mean bed elevation, while the difference between crest elevation and water surface accounts for ∼30%. Our analysis provides a scaling for bar-scale inclined strata formed by avalanching and suggests risk of systematic bias in paleodepth estimation if mean thickness measurements of these deposits are equated to mean bankfull depth.

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41

Gani, Md Ataul, Johannes van der Kwast, Michael E. McClain, Gretchen Gettel, and Kenneth Irvine. "Classification of Geomorphic Units and Their Relevance for Nutrient Retention or Export of a Large Lowland Padma River, Bangladesh: A NDVI Based Approach." Remote Sensing 14, no. 6 (March 18, 2022): 1481. http://dx.doi.org/10.3390/rs14061481.

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Geomorphic classification of large rivers identifies morphological patterns, as a foundation for estimating biogeochemical and ecological processes. In order to support the modelling of in-channel nutrient retention or export, the classification of geomorphic units (GUs) was done in the Padma River, Bangladesh, a large and geomorphically-complex lowland river. GUs were classified using the normalized difference vegetation index (NDVI) four times over a year, so as to cover the seasonal variation of water flows. GUs were categorized as primary and secondary channels (C & S); longitudinal bar (L); transverse bar (T); side bar (SB); unvegetated bank (EK); dry channel (ED); island (VI); and water depression (WD). All types of GUs were observed over the four distinct annual seasons, except ED, which was absent during the high flow, monsoon season. Seasonal variation of the surface area of GUs and discharge showed an inverse relation between discharge and exposed surface areas of VI, L, T, and SB. Nutrients mainly enter the river system through water and sediments, and during monsoon, the maximum portion of emergent GUs were submerged. Based on the assumption that nutrient retention is enhanced in the seasonally inundated portions of GUs, nutrient retention-/export-relevant geomorphic units (NREGUs) were identified. Seasonal variation in the area of NREGUs was similar to that of GUs. The mean NDVI values of the main identified NREGUs were different. The variation of NDVI values among seasons in these NREGUs resulted from changes of vegetation cover and type. The variation also occurred due to alteration of the surface area of GUs in different seasons. The changes of vegetation cover indicated by NDVI values across seasons are likely important drivers for biogeochemical and ecological processes.

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42

Ali, Hydar Lafta, Badronnisa Yusuf, Thamer Ahamed Mohammed, Yasuyuki Shimizu, Mohd Shahrizal Ab Razak, and Balqis Mohamed Rehan. "Improving the Hydro-Morpho Dynamics of A River Confluence by Using Vanes." Resources 8, no. 1 (January 1, 2019): 9. http://dx.doi.org/10.3390/resources8010009.

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Controlling the flow and bed morphology in a river confluence is important in training and navigation works. The flow in river confluence is highly complex due to crucial and rapid changes associated with flow dynamics, sediment transport, and geomorphology. The flow in Malaysia’s rivers has many confluence junctions in natural drains of catchment areas. The confluence between Kurau and Ara Rivers, in Perak, Malaysia, is selected to investigate the scour hole that usually forms in the erosion zone and the bar that forms in the deposition zone. A 2D numerical model is used in simulating hydro-morpho dynamics in the rivers confluence to mitigate the erosion and deposition zones by adopting vanes as control structures. Simulation results suggest that the most effective location, dimension, and angle of vanes can be decided based on their performance in scouring and deposition zones. The distribution velocity and flow vectors can help in deciding the location of the vanes.

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Kuroiwa, Masamitsu, Yuhei Matsubara, Yoko Suzuki, and Takayuki Kuchiishi. "Numerical Model for Predicting Sand Bar Formation around River Mouth." Journal of Korean Society of Coastal and Ocean Engineers 26, no. 2 (April 30, 2014): 96–102. http://dx.doi.org/10.9765/kscoe.2014.26.2.96.

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AN, Hsuan-pei, Su-chin CHEN, Hsun-chuan CHAN, and Yi HSU. "Dimension and frequency of bar formation in a braided river." International Journal of Sediment Research 28, no. 3 (September 2013): 358–67. http://dx.doi.org/10.1016/s1001-6279(13)60046-3.

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Das, S. S., Atul Kumar Singh, and Nisha Singh. "Provenance of bar-top sediments at Tons river near Allahabad." Journal of the Geological Society of India 89, no. 5 (May 2017): 503–10. http://dx.doi.org/10.1007/s12594-017-0638-3.

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Jaballah, Mohamed, Benoît Camenen, Lionel Pénard, and André Paquier. "Alternate bar development in an alpine river following engineering works." Advances in Water Resources 81 (July 2015): 103–13. http://dx.doi.org/10.1016/j.advwatres.2015.03.003.

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Ham, Darren, and Michael Church. "Morphodynamics of an extended bar complex, Fraser River, British Columbia." Earth Surface Processes and Landforms 37, no. 10 (April 4, 2012): 1074–89. http://dx.doi.org/10.1002/esp.3231.

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Dos Santos, Vanessa Cristina, and José Cândido Stevaux. "GÊNESE DE BARRAS DE SOLDAMENTO E SUAS CARACTERÍSTICAS MORFOLÓGICAS: ALTO RIO PARANÁ, BRASIL / Attachment Bars Genesis and Morphological Features: Upper Paraná River, Brazil." Geographia Meridionalis 2, no. 1 (June 29, 2016): 127. http://dx.doi.org/10.15210/gm.v2i1.8102.

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O rio Paraná, em seu trecho natural, é caracterizado por canais secundários de diferentes ordens de tamanho, separando diversas ilhas e barras fluviais. As barras fluviais apresentam grande porte e suas formas mudam constantemente conforme a magnitude do fluxo. Este estudo apresenta a caracterização morfológica de uma barra de soldamento e suas adjacências, situadas junto à ilha Santa Rosa, no alto rio Paraná. Para tanto, a morfologia da barra foi comparada em dois momentos hidrológicos distintos através de levantamentos com aparelho de batimetria. Os resultados evidenciam que a morfologia da barra estudada está diretamente influenciada pelas oscilações da vazão do rio Paraná. No período de águas altas há maior retrabalhamento da forma, e preservação parcial em período de águas médias. A análise da distribuição das formas adjacentes à barra de soldamento permitiu constatar que o canal principal possui mais energia, já que apresenta formas íngremes e profundas, e o canal secundário indica menor energia de fluxo por apresentar formas mais suaves.AbstractThe Paraná River, in its natural reach is characterized by secondary channels of different size orders, which separates several islands and bars. Fluvial bars are large and their forms change constantly due to the flow. This study presents the morphological characterization of an attachment bar and its adjacencies, located nearby the island Santa Rosa, in the upper Paraná River. Therefore, the morphology of the bar was compared in two distinct hydrological moments through surveys with bathymetry equipment. The results indication that the morphology of the studied bar is directly influenced by fluctuations in the flow of the Paraná River. In the period of high water level there is more reworking of the forms and partial preservation in average water level. The analysis of the distribution of forms adjacent to the attachment bar allowed establishing that the main channel is more energetic, as it presents abrupt and deep forms and the secondary channel indicates lower energy flow by presenting smoother forms.Keywords:Paraná River, Fluvial Geomorphology, Morphology, Attachment Bar

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UDA, Takaaki, Yasuhiro KATAYAMA, Nobuo MORI, Isao TAKAHASHI, Kou FURUIKE, and Masumi SERIZAWA. "RIVER MOUTH IMPROVEMENT USING AN ARTIFICIAL REEF TO REDUCE BERM HEIGHT OF RIVER MOUTH BAR." PROCEEDINGS OF HYDRAULIC ENGINEERING 51 (2007): 619–24. http://dx.doi.org/10.2208/prohe.51.619.

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Heritage, George, and Neil Entwistle. "Impacts of River Engineering on River Channel Behaviour: Implications for Managing Downstream Flood Risk." Water 12, no. 5 (May 11, 2020): 1355. http://dx.doi.org/10.3390/w12051355.

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Although knowledge of sediment transport has improved over the last 25 years, our understanding of bedload transfer and sediment delivery is still based on a limited set of observations or on models that make assumptions on hydraulic and sediment transport processes. This study utilises repeat lidar survey data of the River Caldew above the City of Carlisle in the UK to investigate the balance of erosion and deposition associated with channel switching from an engineered and managed single thread channel to a naturalising incipient wandering system. Over the 11-year survey period (four bankfull flood events) around 271,000 m3 of sediment were delivered to the river and floodplain and 197,000 m3 eroded suggesting that storage rates of around 7000 m3/annum occurred. The balance of erosion and deposition is influenced by channelisation with very restricted overbank sedimentation and only limited local and transient in-channel bar deposition along the engineered reach (8000 m3 eroded). This contrasts with the activity of the naturalising reach downstream where a developing wandering channel system is acting to store coarse sediment in-stream as large bar complexes and the associated upstream aggrading plane bed reaches and overbank as splay deposits (87,000 m3 stored). Such behavior suggests that naturalisation of channelised systems upstream of flood vulnerable urban areas can have a significant impact on sediment induced flooding downstream. This conclusion must, however, be moderated in the light of the relatively small volumes of material needed to instigate local aggradation in over-capacity urban channels.

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Journal articles on the topic 'River bar'

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