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1
Vandenberghe, Jef, and Ming-ko Woo. "Modern and ancient periglacial river types." Progress in Physical Geography: Earth and Environment 26, no. 4 (December 2002): 479–506. http://dx.doi.org/10.1191/0309133302pp349ra.
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Climate has been proposed conventionally as the primary factor that determines periglacial river activity (aggradation) and pattern (braided). This concept does not explain the rich diversity in river patterns and morphological processes in both the present and past periglacial environments: besides braided rivers and sandur, meandering, anabranching, transitional and deltaic rivers also occur. A first attempt is made to combine past and present periglacial river types with regard to their morphology, processes and environments. The processes that control river energy and morphology are discussed especially for periglacial conditions. This approach permits an assessment of the responses of periglacial rivers to climatic conditions and the modulation of the responses due to changes in the basin properties. Examples drawn from palaeo- and present-day periglacial rivers and environments demonstrate that there is no unique type of periglacial river but rather an azonal fluvial system with a number of periglacial variants.
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Schwenk, Jon, Anastasia Piliouras, and Joel C. Rowland. "Determining flow directions in river channel networks using planform morphology and topology." Earth Surface Dynamics 8, no. 1 (February 12, 2020): 87–102. http://dx.doi.org/10.5194/esurf-8-87-2020.
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Abstract. The abundance of global, remotely sensed surface water observations has accelerated efforts toward characterizing and modeling how water moves across the Earth's surface through complex channel networks. In particular, deltas and braided river channel networks may contain thousands of links that route water, sediment, and nutrients across landscapes. In order to model flows through channel networks and characterize network structure, the direction of flow for each link within the network must be known. In this work, we propose a rapid, automatic, and objective method to identify flow directions for all links of a channel network using only remotely sensed imagery and knowledge of the network's inlet and outlet locations. We designed a suite of direction-predicting algorithms (DPAs), each of which exploits a particular morphologic characteristic of the channel network to provide a prediction of a link's flow direction. DPAs were chained together to create “recipes”, or algorithms that set all the flow directions of a channel network. Separate recipes were built for deltas and braided rivers and applied to seven delta and two braided river channel networks. Across all nine channel networks, the recipe-predicted flow directions agreed with expert judgement for 97 % of all tested links, and most disagreements were attributed to unusual channel network topologies that can easily be accounted for by pre-seeding critical links with known flow directions. Our results highlight the (non)universality of process–form relationships across deltas and braided rivers.
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Chalov, R. S., and E. R. Chalova. "Geography of braided rivers within the territory of Russia." Известия Русского географического общества 151, no. 6 (December 20, 2019): 20–34. http://dx.doi.org/10.31857/s0869-6071151620-34.
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The paper represents the geographical analysis of braided river channels development and distribution for the first time in Russian Scientific Literature. On asmall-scale map of Russia we display the distribution of braided channels on small and middle mountain, semi-mountain and plain rivers, in free and limited conditions of channel changes development (on rivers with wide floodplain and incised channel), which are determined by geologic-geomorphologic structure of the territory. On the large and largest rivers we distinguish braided reaches of different morphological types according to the MSU classification (single, conjugated, one-sided and alternate one-sided, sub-parallel branches, etc) and also bifurcations as aconsequence of meander cut-off which complicate the morphology of straight and meandering channels. Separately we display bifurcations on the other structural levels of channel processes development point mid-channel bifurcations on mountain reaches of large rivers, split channels and deltaic braided reaches. The causes of different types of braided channels development in different natural conditions are described.
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Germanoski, Dru, and S. A. Schumm. "Changes in Braided River Morphology Resulting from Aggradation and Degradation." Journal of Geology 101, no. 4 (July 1993): 451–66. http://dx.doi.org/10.1086/648239.
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GOSWAMI, PRADEEP K., and TANUJA DEOPA. "Channel morphology, hydrology and geomorphic positioning of a Middle Miocene river system of the Siwalik foreland basin, India." Geological Magazine 152, no. 1 (April 15, 2014): 12–27. http://dx.doi.org/10.1017/s0016756814000090.
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AbstractSystematic lithofacies, palaeocurrent, palaeomorphological and palaeohydrological analyses have provided detailed information about a hitherto unstudied river system of the Siwalik foreland basin of the Himalaya. Three distinct lithofacies associations, each representing a specific depositional setting, have been identified and named as ‘Facies Association A’, ‘Facies Association B’ and ‘Facies Association C’. The ‘Facies Association A’ comprises pebbly sandstone, cross-bedded sandstone, ripple-laminated sandy siltstone and bioturbated mudstone lithofacies and represents deposits of a braided channel. The ‘Facies Association B’ comprises cross-bedded sandstone, bioturbated mudstone, fine sandstone–mudstone alternation and lensoid to prismatic sandstone lithofacies and represents deposits of a channel, natural levee, crevasse-splay and flood plain of a meandering stream. The ‘Facies Association C’ comprises mottled siltstone–mudstone heterolith and fine sandstone lithofacies and represents deposits of the upland interfluve region. The braided stream had a maximum depth of 4.15 m, maximum width of 305 m and maximum discharge of 7045 cumec, whereas the meandering stream had a sinuosity of 1.26, maximum depth of 3.71 m, maximum width of 180 m and maximum discharge of 4070 cumec. The area had a regional radial outward flow pattern, but dominantly towards the SSW. However, the braided river had a bimodal flow pattern due to an active basement-high-induced bend along its course. A comparison of the sediment characters and morphological and hydrological parameters of these streams with those of the modern rivers of the Ganga (Gangetic) basin has enabled us to infer that this river system was located in the medial-distal megafan-interfan setting of the basin.
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Mosley, P., and I. Jowett. "River morphology and management in New Zealand." Progress in Physical Geography: Earth and Environment 23, no. 4 (December 1999): 541–65. http://dx.doi.org/10.1177/030913339902300405.
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River research in New Zealand is strongly conditioned by management requirements defined by environmental legislation. Principal areas of investigation at present include information on river morphology, habitat and instream flows required for management of fluvial ecosystems; erosion, sediment transport and sediment yield; and gravel-bedded and braided river processes. Research in these areas has tended to have a strong orientation towards field observations as a basis for developing quantitative (commonly statistical) models, and ultimately the provision of guidance material and decision support systems for resource managers. A fourth area of particular emphasis has been channel networks and hydraulic geometry. Again, the work generally has been field-intensive, but has been directed towards testing models such as the optimal channel network concept. Current research directions are focusing particularly on gravel-bed river mechanics, climatic and tectonic controls on landscape evolution, and instream habitat hydraulics and ecosystems.
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Ashmore, Peter. "Intensity and characteristic length of braided channel patternsThis paper is one of a selection of papers in this Special Issue in honour of Professor M. Selim Yalin (1925–2007)." Canadian Journal of Civil Engineering 36, no. 10 (October 2009): 1656–66. http://dx.doi.org/10.1139/l09-088.
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Recent research on braided river morphology shows that the intensity (number of anabranches) of braiding channels increases with dimensionless discharge and (or) stream power. This variation in intensity reflects the adjustment of total sinuosity of the river to imposed gradient at a given discharge and grain size. Only a subset of channels is active at a given time and this active braiding intensity reflects the limited number of channels that can sustain bed load transport as the flow is divided. This is governed mechanistically by the dynamics of bifurcations and avulsions. Braided channel networks also have a characteristic length scale (or scales) related to the wavelength of the bars from which braiding develops and to the scale of the bars and confluence–bifurcation units within the braided network. The range of scales is limited by the size (and, therefore, number) of the active channels within the network and the width of the entire river.
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Ziliani, Luca, Nicola Surian, Gianluca Botter, and Luca Mao. "Assessment of the geomorphic effectiveness of controlled floods in a braided river using a reduced-complexity numerical model." Hydrology and Earth System Sciences 24, no. 6 (June 22, 2020): 3229–50. http://dx.doi.org/10.5194/hess-24-3229-2020.
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Abstract. Most Alpine rivers have undergone significant alterations in flow and sediment regimes. These alterations have notable effects on river morphology and ecology. One option to mitigate such effects is flow regime management, specifically through the reintroduction of channel-forming discharges. The aim of this work is to assess the morphological changes induced in the Piave River (Italy) by two distinct controlled-flood strategies, the first characterized by a single artificial flood per year and the second by higher-magnitude but less frequent floods. This work involved applying a two-dimensional reduced-complexity morphodynamic model (CAESAR-LISFLOOD) to a 7 km long reach, characterized by a braided pattern and highly regulated discharges. Numerical modelling allowed the assessment of morphological changes for four long-term scenarios (2009–2034). The scenarios were defined considering the current flow regime and the natural regime, which was estimated by a stochastic physically based hydrologic model. Changes in channel morphology were assessed by measuring active-channel width and braiding intensity. A comparison of controlled-flood scenarios to a baseline scenario (i.e. no controlled floods) showed that artificial floods had little effect on channel morphology. More channel widening (13.5 %) resulted from the high-magnitude flood strategy than from the application of the other strategy (8.6 %). Negligible change was observed in terms of braiding intensity. The results indicate that controlled floods do not represent an effective solution for morphological recovery in braided rivers with strongly impacted flow and sediment regimes.
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Métivier, F., O. Devauchelle, H. Chauvet, E. Lajeunesse, P. Meunier, K. Blanckaert, Z. Zhang, et al. "Morphology of meandering and braided gravel-bed streams from the Bayanbulak Grassland, Tianshan, China." Earth Surface Dynamics Discussions 3, no. 4 (November 13, 2015): 1289–316. http://dx.doi.org/10.5194/esurfd-3-1289-2015.
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Abstract. The Bayanbulak Grassland, Tianshan, China is located in an intramountane sedimentary basin where meandering and braided gravel-bed streams coexist under the same climatic and geological settings. We report on measurements of their discharge, width, depth, slope and grain size. Based on this data set, we compare the morphology of individual threads from braided and meandering streams. Both types of threads share statistically indistinguishable regime relations. Their depths and slopes compare well with the threshold theory, but they are wider than predicted by this theory. These findings are reminiscent of previous observations from similar gravel-bed streams. Using the scaling laws of the threshold theory, we detrend our data with respect to discharge to produce a homogeneous statistical ensemble of width, depth and slope measurements. The statistical distributions of these dimensionless quantities are similar for braided and meandering streams. This suggests that a braided river is a collection of intertwined channels, which individually resemble isolated streams. Given the environmental conditions in Bayanbulak, we furthermore hypothesize that bedload transport causes the channels to be wider than predicted by the threshold theory.
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Leduc, Pauline, Sarah Peirce, and Peter Ashmore. "Short communication: Challenges and applications of structure-from-motion photogrammetry in a physical model of a braided river." Earth Surface Dynamics 7, no. 1 (January 24, 2019): 97–106. http://dx.doi.org/10.5194/esurf-7-97-2019.
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Abstract. For extending the applications of structure-from-motion (SfM) photogrammetry in river flumes, we present the main challenges and methods used to collect a large dataset (>1000 digital elevation models, DEMs) of high-quality topographic data using close-range SfM photogrammetry with a resulting vertical precision of ∼1 mm. Automatic target detection, batch processing, and considerations for image quality were fundamental to the successful implementation of the SfM technique on such a large dataset, which was used primarily for capturing details of gravel-bed braided river morphodynamics and sedimentology. While the applications of close-range SfM photogrammetry are numerous, we include sample results from DEM differencing, which was used to quantify morphology change and provide estimates of water depth in braided rivers, as well as image analysis for mapping bed surface texture. These methods and results contribute to the growing field of SfM applications in geomorphology and close-range experimental settings in general.
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Legleiter, Carl, and Brandon Overstreet. "Measuring the Morphology and Dynamics of the Snake River by Remote Sensing." UW National Parks Service Research Station Annual Reports 37 (January 1, 2014): 12–20. http://dx.doi.org/10.13001/uwnpsrc.2014.4035.
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The Snake River is a prominent, central feature of Grand Teton National Park, and this dynamic fluvial system maintains diverse habitats while actively shaping the landscape. Although the riparian corridor is relatively pristine, the Snake River is by no means free from anthropogenic influences: streamflows have been regulated since 1907 by Jackson Lake Dam. Among dam-controlled rivers in the western U.S., the Snake River is unique in that tributaries entering below the dam supply sufficient coarse bed material to produce a braided morphology. As a result of tributary inputs, sediment flux along the Snake River has been relatively unaffected by Jackson Lake Dam, but flow regulation has reduced the magnitude and altered the timing of streamflows. In this study we are coupling an annual image time series with extensive field surveys to document channel changes occurring on the Snake River. Our objective is to quantify how snowmelt runoff events and flow management strategies influence patterns of sediment transfer and storage throughout the river system, with a particular focus on tributary junctions. More specifically, we are using the image sequence to identify areas of erosion and deposition and hence infer the sediment flux associated with the observed changes in channel morphology. This analysis will improve our understanding of the riverâs response to flow management and enable us to generate hypotheses as to how the system might adapt to future anthropogenic and/or climate-driven alterations in streamflow and sediment supply. In addition, our research on the Snake River involves an ongoing assessment of the potential to measure the morphology and dynamics of large, complex rivers via remote sensing. A new aspect of this investigation involves estimating flow velocities from hyperspectral images that capture the texture of the water surface. Extensive field measurements of velocity and water surface roughness are being used to develop this innovative approach and thus increase the amount of river information that can be inferred via remote sensing.
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Rashid, Bazlar, Sultan Ul Islam, and Badrul Islam. "River morphology and evolution of the Barind Tract, Bangladesh." Journal of Nepal Geological Society 49, no. 1 (December 31, 2015): 65–76. http://dx.doi.org/10.3126/jngs.v49i1.23144.
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The Barind Tract is an elevated Pleistocene Terraces (about 11-48 mamsl) in northwestern Bangladesh and is widely accepted Tract to have been evolved from tectonic upliftment and /or exists as an erosional geomorphic feature. Some part of the Barind Tract bears the characteristics of morphological origin but some areas are providing evidences of tectonic upliftment. The present study is an attempt to interpret the morphological characteristics of the rivers in the area and tried to unveiling the processes that are responsible for the evolution of the Tract. River morphology are interpreted from satellite images and field mapping and are used to relate neotectonic activities occurred in the area. The river forms U-shaped valleys in floodplain areas whereas these are V-shaped within the Barind Tract. The rivers and valleys on the Tract are also comparatively more straight, incised and entrenched, and rivers are tightly meandered, more localized, form paired and unpaired terraces, and antecedent in nature, whereas, the rivers in the floodplain are either meandering, braided or anastomosing drainage channels. Along the boundary between Barind and floodplain the rivers form asymmetric valley with steeping bank along the tract sides. The width/ depth (W/D) ratios of these rivers are much lower within or near to the Tract than the nearby floodplain. The rivers fl owing from the Himalayas change their morphology, trend, nature etc. near and within the Tract. Some of the N-S fl owing rivers turned towards southeast and southwest directions to maintain slope of the uplifted Tract. These are the indication of structural control of these rivers as well as the tectonic origin of the Barind Tract rather than only geomorphic origin. Earthquakes in this region in the recent past also support the same view about structural control and neotectonic activities.
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Bellwald, B., S. Planke, S. Polteau, N. Lebedeva-Ivanova, J. I. Faleide, S. M. Morris, S. Morse, and S. Castelltort. "Characterization of a glacial paleo-outburst flood using high-resolution 3-D seismic data: Bjørnelva River Valley, SW Barents Sea." Journal of Glaciology 67, no. 263 (January 22, 2021): 404–20. http://dx.doi.org/10.1017/jog.2020.115.
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AbstractProglacial braided river systems discharge large volumes of meltwater from ice sheets and transport coarse-grained sediments from the glaciated areas to the oceans. Here, we test the hypothesis if high-energy hydrological events can leave distinctive signatures in the sedimentary record of braided river systems. We characterize the morphology and infer a mode of formation of a 25 km long and 1–3 km wide Early Pleistocene incised valley recently imaged in 3-D seismic data in the Hoop area, SW Barents Sea. The fluvial system, named Bjørnelva River Valley, carved 20 m deep channels into Lower Cretaceous bedrock at a glacial paleo-surface and deposited 28 channel bars along a paleo-slope gradient of ~0.64 m km−1. The landform morphologies and position relative to the paleo-surface support that Bjørnelva River Valley was formed in the proglacial domain of the Barents Sea Ice Sheet. Based on valley width and valley depth, we suggest that Bjørnelva River Valley represents a braided river system fed by violent outburst floods from a glacial lake, with estimated outburst discharges of ~160 000 m3 s−1. The morphological configuration of Bjørnelva River Valley can inform geohazard assessments in areas at risk of outburst flooding today and is an analogue for landscapes evolving in areas currently covered by the Greenland and Antarctic ice sheets.
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Misset, Clément, Alain Recking, Cédric Legout, Alain Poirel, and Marine Cazilhac. "Geomorphological factors influencing hysteresis patterns between suspended load and flow rate in Alpine rivers." E3S Web of Conferences 40 (2018): 04004. http://dx.doi.org/10.1051/e3sconf/20184004004.
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Suspended sediment load represents a large part of total solid fluxes transported in most rivers. Thus, for hydropower plan management or for environmental issues, it is crucial to understand how these sediments are produced, stored and transported in a given catchment. Hysteresis loops in discharge-suspended load signals are commonly used to assess sediment sources and production processes but most of the time the shape of this relation is analyzed qualitatively on short time series or for few events. In this study we analyzed quantitatively 10 long time series of suspended sediment load of various alpine catchments. This method allows us to compare events and to assess to which extent fine sediments originate from hillslope erosion processes or from river bed remobilization. We found that watersheds with braided bed morphology are dominated by clockwise loops while those with narrower bed as step-pool morphology are dominated by counter-clockwise hysteresis or have no general trend. These results suggest that storage and remobilization of fine sediments within the bed could play a major role in suspended sediment transport in Alpine streams, especially in large braided rivers.
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Warburton, Jeff, and Tim Davies. "Variability of bedload transport and channel morphology in a braided river hydraulic model." Earth Surface Processes and Landforms 19, no. 5 (August 1994): 403–21. http://dx.doi.org/10.1002/esp.3290190503.
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Fournier, B., C. Guenat, G. Bullinger-Weber, and E. A. D. Mitchell. "Spatio-temporal heterogeneity of riparian soil morphology in a restored floodplain." Hydrology and Earth System Sciences Discussions 10, no. 4 (April 5, 2013): 4337–67. http://dx.doi.org/10.5194/hessd-10-4337-2013.
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Abstract. Floodplains have been intensively altered in industrialized countries, but are now increasingly being restored and it is therefore important to assess the effect of these restoration projects on the aquatic and terrestrial components of ecosystems. Soils are a functionally crucial component of terrestrial ecosystems but are generally overlooked in floodplain restoration assessment. We studied the spatio-temporal heterogeneity of soil morphology in a restored (riverbed widening) river reach along River Thur (Switzerland) using three criteria (soil diversity, dynamism and typicality) and their associated indicators. We hypothesized that these criteria would correctly discriminate the post-restoration changes in soil morphology within the study site, and that these changes correspond to patterns of vascular plant diversity. Soil diversity and dynamism increased five years after the restoration, but typical soils of braided rivers were still missing. Soil typicality and dynamism correlated to vegetation changes. These results suggest a limited success of the project in agreement with evaluations carried out at the same site using other, more resource demanding methods (e.g. soil fauna, fish, ecosystem functioning). Soil morphology provides structural and functional information on floodplain ecosystems and allows predicting broad changes in plant diversity. The spatio-temporal heterogeneity of soil morphology represents a cost-efficient ecological indicator that could easily be integrated into rapid assessment protocols of floodplain and river restoration projects.
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Wu, Xinyu, Zhiwei Li, Peng Gao, Cao Huang, and Tiesong Hu. "Response of the Downstream Braided Channel to Zhikong Reservoir on Lhasa River." Water 10, no. 9 (August 27, 2018): 1144. http://dx.doi.org/10.3390/w10091144.
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Lhasa River basin is situated in the southern part of the Qinghai-Tibet Plateau, which is the most important region of economic and social development in Tibet. In order to efficiently utilize water resources in the basin and ease the shortage of regional electric power supply, Zhikong Reservoir was built in the upstream reach of the Lhasa River in 2006. Impoundment of this reservoir evidently affected the morphology and stability of the downstream braided channel below the dam. Yet, little is known about the complex responses of the downstream braided channel to the Zhikong Dam. Landsat images in the 2000–2016 period, together with daily discharges and field observations in the 2017–2018 period, were used to investigate the morphological response of the braided channel to the Zhikong Dam. The downstream Lhasa River below the Zhikong Dam was divided into four reaches (i.e., RS1, RS2, RS3 and RS4) based on the confluence of three downstream tributaries. Results showed that the number and area of central bars in the braided reach closest to Zhikong Dam (RS1) were increased because of main channel incision and water level drop. This increasing trend attenuated along the downstream channel of this reach. Braiding number index of multithread channels in RS1 obviously increased by 3 in one section and reduced by 2 in two sections, while changed in all sections randomly with no pronounced trend along the RS2 to RS3 and RS4 reaches. The average bar area in two focus reaches, RS1_B1 and RS2_B2, 6.0 km and 36.8 km far away to the Zhikong Dam, respectively, followed opposite trends with the former increasing and the later reducing. Furthermore, the mean dissection, landscape dissection and fragmentation shape indices in RS1, showed an increasing trend from 2001 to 2016, indicating the shape of irregular central bars varied greatly because clean water release of Zhikong Dam eroded the downstream braided channel.
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Fournier, B., C. Guenat, G. Bullinger-Weber, and E. A. D. Mitchell. "Spatio-temporal heterogeneity of riparian soil morphology in a restored floodplain." Hydrology and Earth System Sciences 17, no. 10 (October 17, 2013): 4031–42. http://dx.doi.org/10.5194/hess-17-4031-2013.
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Abstract. Floodplains have been intensively altered in industrialized countries, but are now increasingly being restored. It is therefore important to assess the effect of these restoration projects on the aquatic and terrestrial components of ecosystems. However, despite being functionally crucial components of terrestrial ecosystems, soils are generally overlooked in floodplain restoration assessments. We studied the spatio-temporal heterogeneity of soil morphology in a restored (riverbed widening) river reach along the River Thur (Switzerland) using three criteria (soil diversity, dynamism and typicality) and their associated indicators. We hypothesized that these criteria would correctly discriminate the post-restoration changes in soil morphology, and that these changes correspond to patterns of vascular plant diversity. Soil diversity and dynamism increased 5 yr after the restoration, but some typical soils of braided rivers were still missing. Soil typicality and dynamism were correlated to vegetation changes. These results suggest a limited success of the project, in agreement with evaluations carried out at the same site using other, more resource-demanding, methods (e.g., soil fauna, fish diversity, ecosystem functioning). Soil morphology provides structural and functional information on floodplain ecosystems. The spatio-temporal heterogeneity of soil morphology represents a cost-efficient ecological indicator that could easily be integrated into rapid assessment protocols of floodplain and river restoration projects. The follow-up assessment after several major floods (≥ HQ20) should take place to allow for testing the longer-term validity of our conclusion for the River Thur site. More generally, it would be useful to apply the soil morphology indicator approach in different settings to test its broader applicability.
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Pavanelli, Donatella, Claudio Cavazza, Stevo Lavrnić, and Attilio Toscano. "The Long-Term Effects of Land Use and Climate Changes on the Hydro-Morphology of the Reno River Catchment (Northern Italy)." Water 11, no. 9 (September 3, 2019): 1831. http://dx.doi.org/10.3390/w11091831.
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Anthropogenic activities, and in particular land use/land cover (LULC) changes, have a considerable effect on rivers’ flow rates and their morphologies. A representative example of those changes and resulting impacts on the fluvial environment is the Reno Mountain Basin (RMB), located in Northern Italy. Characterized by forest exploitation and agricultural production until World War II, today the RMB consists predominantly of meadows, forests and uncultivated land, as a result of agricultural land abandonment. This study focuses on the changes of the Reno river’s morphology since the 1950s, with an objective of analyzing the factors that caused and influenced those changes. The factors considered were LULC changes, the Reno river flow rate and suspended sediment yield, and local climate data (precipitation and temperature). It was concluded that LUCL changes caused some important modifications in the riparian corridor, riverbed size, and river flow rate. A 40–80% reduction in the river bed area was observed, vegetation developed in the riparian buffer strips, and the river channel changed from braided to a single channel. The main causes identified are reductions in the river flow rate and suspended sediment yield (−36% and −38%, respectively), while climate change did not have a significant effect.
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Pisarska-Jamroży, Małgorzata. "Factors controlling sedimentation in the Toruń-Eberswalde ice-marginal valley during the Pomeranian phase of the Weichselian glaciation: an overview." Geologos 21, no. 1 (March 1, 2015): 1–29. http://dx.doi.org/10.1515/logos-2015-0001.
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Abstract During the Pleistocene the Scandinavian ice sheet drained huge quantities of sediment-laden meltwaters. These meltwaters supplied ice-marginal valleys that formed parallel to the front of the ice sheet. Not without significance was the supply of ice-marginal valleys from extraglacial rivers in the south. Moreover, periglacial conditions during and after sedimentation in ice-marginal valleys, the morphology of valley bedrocks, and erosion of older sediments played important roles in the depositional scenarios, and in the mineralogical composition of the sediments. The mechanisms that controlled the supply and deposition in ice-marginal valleys were analysed on the basis of a Pleistocene ice-marginal valley that was supplied by northern and southern source areas in the immediate vicinity. Investigations were conducted in one of the largest ice-marginal valleys of the Polish-German lowlands, i.e., the Toruń-Eberswalde ice-marginal valley, in sandurs (Drawa and Gwda) supplied sediments and waters from the north into this valley, and on extraglacial river terraces (pre-Noteć and pre-Warta rivers), formed simultaneously with the sandurs and ice-marginal valley (Pomeranian phase of Weichselian glaciation) supplied sediments and waters from the south into this valley. A much debated question is how similar, or different, depositional processes and sediments were that contributed to the formation of the Toruń-Eberswalde ice-marginal valley, and whether or not it is possible to differentiate mostly rapidly aggraded sandur sediments from ice-marginal valley sediments. Another question addresses the contribution of extraglacial feeding of the Toruń-Eberswalde ice-marginal valley. These matters were addressed by a wide range of analyses: sediment texture and structure, architectural elements of sediments, frequency of sedimentary successions, heavy-mineral analysis (both transparent and opaque heavy minerals), analysis of rounding and frosting of quartz grains, and palaeohydrological calculations. Additionally, a statistical analysis was used. The specific depositional conditions of distribution of sediments in ice-marginal valley allow to distinguish new environment of ice-marginal valley braided river. The spectrum of depositional conditions in the Toruń-Eberswalde ice-marginal valley and their specific palaeohydraulic parameters allow to distinguish three coexisting zones in the ice-marginal valley braided-river system: (1) deep gravel-bed braided channel zone with extensive scours, (2) deep sand-bed braided channel zone with transverse bars, and (3) marginal sand-bed and gravel-bed braided channel zone with diamicton and breccia deposition, which were characterised in detail. Some of the results have been published previously, which is why they are discussed in the present paper within the context of new data
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Bhuyian, Md N. M., and Alfred Kalyanapu. "Predicting Channel Conveyance and Characterizing Planform Using River Bathymetry via Satellite Image Compilation (RiBaSIC) Algorithm for DEM-Based Hydrodynamic Modeling." Remote Sensing 12, no. 17 (August 28, 2020): 2799. http://dx.doi.org/10.3390/rs12172799.
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Digital Elevation Models (DEMs) are widely used as a proxy for bathymetric data and several studies have attempted to improve DEM accuracy for hydrodynamic (HD) modeling. Most of these studies attempted to quantitatively improve estimates of channel conveyance (assuming a non-braided morphology) rather than accounting for the actual channel planform. Accurate representation of river conveyance and planform in a DEM is critical to HD modeling and can be achieved with a combination of remote sensing (e.g., satellite image) and field data, such as water surface elevation (WSE). Therefore, the objectives of this study are (i) to develop an algorithm for predicting channel conveyance and characterizing planform via satellite images and in situ WSE and (ii) to estimate discharge using the predicted conveyance via an HD model. The algorithm is named River Bathymetry via Satellite Image Compilation (RiBaSIC) and uses Landsat satellite imagery, Shuttle Radar Topography Mission (SRTM) DEM, Multi-Error-Removed Improved-Terrain (MERIT) DEM, and observed WSE. The algorithm is tested on four study areas along the Willamette River, Kushiyara River, Jamuna River, and Solimoes River. Channel slope and predicted hydraulic radius are subsequently estimated for approximating Manning’s roughness factor. Two-dimensional HD models using DEMs modified by the RiBaSIC algorithm and corresponding Manning’s roughness factors are employed for discharge estimation. The proposed algorithm can represent river planform and conveyance in single-channeled, meandering, wandering, and braided river reaches. Additionally, the HD models estimated discharge within 14–19% relative root mean squared error (RRMSE) in simulation of five years period.
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Mueller, Erich R., and John Pitlick. "Sediment supply and channel morphology in mountain river systems: 2. Single thread to braided transitions." Journal of Geophysical Research: Earth Surface 119, no. 7 (July 2014): 1516–41. http://dx.doi.org/10.1002/2013jf003045.
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Ryder, June M., and Michael Church. "The Lillooet terraces of Fraser River: a palaeoenvironmental enquiry." Canadian Journal of Earth Sciences 23, no. 6 (June 1, 1986): 869–84. http://dx.doi.org/10.1139/e86-089.
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The history of Holocene fluvial terraces was investigated by stratigraphic, morphological, and palaeohydrologic methods. The terraces were formed in glaciofluvial and glaciolacustrine sediments by the Fraser River: degradation alternated with episodes of stability and aggradation. The uppermost terraces, four nonpaired surfaces, were occupied by a braided river. Vertical stability was controlled either by the water and sediment discharge of the river or by backwater effects from downstream landslides. The lower terraces, two paired surfaces, and associated fluvial sediments provide evidence for at least two cycles of aggradation and downcutting. These can be attributed to the effects of landslides that occurred a short distance downstream. Climatic variations may also have influenced terrace formation, but direct evidence is lacking. Palaeohydraulic investigations based on gravel texture, terrace gradients, and geometry of palaeochannels provide results that although approximate, conform with conclusions based upon terrace morphology and stratigraphy.
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Tien, Hai Nguyen, Dang Vu Hai, Phuc La The, and Ha Nguyen Thai. "MORPHOLOGICAL CHARACTERISTICS OF THE GIANH RIVER (FROM CO CANG TO CUA GIANH) IN RELATION TO THE EROSION AND ACCUMULATION." Tạp chí Khoa học và Công nghệ biển 18, no. 4 (March 15, 2019): 384–92. http://dx.doi.org/10.15625/1859-3097/18/4/13658.
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On the basis of morphological characteristics and erosion - accumulation of sediment, it is possible to divide the stretch of the Gianh River from Co Cang to Cua Gianh (about 54km in length) into 3 sections as follows: Meandering channel (from Co Cang to Tien Xuan Isles): the length of the channel is 27.69km and the width of the channel is 80-250m. The channel is in the form of a meandering, narrow riverbed, flow plays a dominant role, deposition activities develop strongly at the convex side, while erosion occurs strongly in the concave side (cut side); Braided channel (from Tien Xuan Isles to Quang Phu): the length of the channel is 17.06km and the width of the channel is 800-2,200m. The channel is straight, the river bed is large and the depth of the river bed is 2-11m. Sedimentation occurs mainly at the bottom of the channel and creates bar in the middle of the channel; Straight channel (from Quang Phu to Cua Gianh): the length of the channel is 9.23km and the width of the channel is 800-1,000m. The channel is straight and the depth of the river bed is 8-12.5m. In addition to the role of river flow, it is strongly influenced by marine dynamics. The erosion and accretion activities occur mainly in estuaries. The results above show trend of river development: i) Meandering channel is the most vulnerable to changes for morphology of channel by erosion and accretion of sediment and can create 1-2 horseshoe pools by the river change line; ii) Braided channel mainly changes in the bottom of channel by the formation of channel bar; iii) Straight channel mainly changes in the estuary (the mouth of the river can be moved, enlarged or narrowed).
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Braat, Lisanne, Thijs van Kessel, Jasper R. F. W. Leuven, and Maarten G. Kleinhans. "Effects of mud supply on large-scale estuary morphology and development over centuries to millennia." Earth Surface Dynamics 5, no. 4 (October 9, 2017): 617–52. http://dx.doi.org/10.5194/esurf-5-617-2017.
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Abstract. Alluvial river estuaries consist largely of sand but are typically flanked by mudflats and salt marshes. The analogy with meandering rivers that are kept narrower than braided rivers by cohesive floodplain formation raises the question of how large-scale estuarine morphology and the late Holocene development of estuaries are affected by cohesive sediment. In this study we combine sand and mud transport processes and study their interaction effects on morphologically modelled estuaries on centennial to millennial timescales. The numerical modelling package Delft3D was applied in 2-DH starting from an idealised convergent estuary. The mixed sediment was modelled with an active layer and storage module with fluxes predicted by the Partheniades–Krone relations for mud and Engelund–Hansen for sand. The model was subjected to a range of idealised boundary conditions of tidal range, river discharge, waves and mud input. The model results show that mud is predominantly stored in mudflats on the side of the estuary. Marine mud supply only influences the mouth of the estuary, whereas fluvial mud is distributed along the whole estuary. Coastal waves stir up mud and remove the tendency to form muddy coastlines and the formation of mudflats in the downstream part of the estuary. Widening continues in estuaries with only sand, while mud supply leads to a narrower constant width and reduced channel and bar dynamics. This self-confinement eventually leads to a dynamic equilibrium in which lateral channel migration and mudflat expansion are balanced on average. However, for higher mud concentrations, higher discharge and low tidal amplitude, the estuary narrows and fills to become a tidal delta.
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Kiss, Tímea, and Márton Balogh. "Characteristics of Point-Bar Development under the Influence of a Dam: Case Study on the Dráva River at Sigetec, Croatia." Journal of Environmental Geography 8, no. 1-2 (July 1, 2015): 23–30. http://dx.doi.org/10.1515/jengeo-2015-0003.
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Abstract Before the extensive engineering works the Dráva River had braided pattern. However in the 19-20th centuries river regulation works became widespread, thus meanders were cut off, side-channels were blocked and hydroelectric power plants were completed. These human impacts significantly changed the hydro-morphology of the river. The aim of the present research is to analyse meander development and the formation of a point-bar from the point of view of indirect human impact. Series of maps and ortho-photos representing the period of 1870-2011 were used to quantify the longterm meander development, rate of bank erosion and point-bar aggradation. Besides, at-a-site erosion measurements and grain-size analysis were also carried out. As the result of reservoir constructions during the last 145 years floods almost totally disappeared, as their return period increased to 5-15 years and their duration decreased to 1-2 days. The channel pattern had changed from braided to sinuous and to meandering, thus the rate of bank erosion increased from 3.7 m/y to 32 m/y. On the upstream part of the point-bar the maximum grain size is 49.7-83.4 mm and the mean particle size is 7.6 mm, whilst on the downstream part the maximum grain size was only 39.7-39.9 mm and mean sediment size decreased to 6.1 mm. Due to the coarse sediment supply and the decreasing stream energy the point-bars develop quickly upstream and laterally too.
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Lindenschmidt, Karl-Erich, and Kwok P. Chun. "Evaluating the impact of fluvial geomorphology on river ice cover formation based on a global sensitivity analysis of a river ice model." Canadian Journal of Civil Engineering 40, no. 7 (July 2013): 623–32. http://dx.doi.org/10.1139/cjce-2012-0274.
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In 2011, Manitoba was stricken by wide-scale flooding causing high flows along the Dauphin River. The unprecedented high discharges at freeze-up created the potential for excessive ice cover thickening and backwater staging exacerbating the flood risk already threatening the communities along the river and upstream-lying Lake St. Martin. Hence, the river ice model RIVICE was implemented to determine flood protection elevations to which existing dikes needed to be raised and extended. Two reaches of the river were modelled separately representing distinct geomorphological characteristics: mildly sloping, more sinuous upper reach and steeper, more channelized lower reach. A global sensitivity analysis based on a Monte Carlo analysis was carried out to determine how differences in these morphological features influence different processes of the ice cover formation. It was found that the sinuous and braided morphology of the upper reach has a marked impact on the sensitivity of the hydraulic roughness and strength parameters. The structure of the ice (porosity) and the discharge were most sensitive to the backwater level outcomes of the steeper and straighter lower reach.
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Schneider, Raphael, Peter Nygaard Godiksen, Heidi Villadsen, Henrik Madsen, and Peter Bauer-Gottwein. "Application of CryoSat-2 altimetry data for river analysis and modelling." Hydrology and Earth System Sciences 21, no. 2 (February 7, 2017): 751–64. http://dx.doi.org/10.5194/hess-21-751-2017.
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Abstract. Availability of in situ river monitoring data, especially of data shared across boundaries, is decreasing, despite growing challenges for water resource management across the entire globe. This is especially valid for the case study of this work, the Brahmaputra Basin in South Asia. Commonly, satellite altimeters are used in various ways to provide information about such river basins. Most missions provide virtual station time series of water levels at locations where their repeat orbits cross rivers. CryoSat-2 is equipped with a new type of altimeter, providing estimates of the actual ground location seen in the reflected signal. It also uses a drifting orbit, challenging conventional ways of processing altimetry data to river water levels and their incorporation in hydrologic–hydrodynamic models. However, CryoSat-2 altimetry data provides an unprecedentedly high spatial resolution. This paper suggests a procedure to (i) filter CryoSat-2 observations over rivers to extract water-level profiles along the river, and (ii) use this information in combination with a hydrologic–hydrodynamic model to fit the simulated water levels with an accuracy that cannot be reached using information from globally available digital elevation models (DEMs) such as from the Shuttle Radar Topography Mission (SRTM) only. The filtering was done based on dynamic river masks extracted from Landsat imagery, providing spatial and temporal resolutions high enough to map the braided river channels and their dynamic morphology. This allowed extraction of river water levels over previously unmonitored narrow stretches of the river. In the Assam Valley section of the Brahmaputra River, CryoSat-2 data and Envisat virtual station data were combined to calibrate cross sections in a 1-D hydrodynamic model of the river. The hydrologic–hydrodynamic model setup and calibration are almost exclusively based on openly available remote sensing data and other global data sources, ensuring transferability of the developed methods. They provide an opportunity to achieve forecasts of both discharge and water levels in a poorly gauged river system.
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Lallias-Tacon, S., F. Liébault, and H. Piégay. "Use of airborne LiDAR and historical aerial photos for characterising the history of braided river floodplain morphology and vegetation responses." CATENA 149 (February 2017): 742–59. http://dx.doi.org/10.1016/j.catena.2016.07.038.
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Kang, Taeun, Ichiro Kimura, and Yasuyuki Shimizu. "Numerical simulation of large wood deposition patterns and responses of bed morphology in a braided river using large wood dynamics model." Earth Surface Processes and Landforms 45, no. 4 (January 2, 2020): 962–77. http://dx.doi.org/10.1002/esp.4789.
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Payenberg, T. H. D., and S. C. Lang. "RESERVOIR GEOMETRY OF FLUVIAL DISTRIBUTARY CHANNELS—IMPLICATIONS FOR NORTHWEST SHELF, AUSTRALIA, DELTAIC SUCCESSIONS." APPEA Journal 43, no. 1 (2003): 325. http://dx.doi.org/10.1071/aj02017.
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The exploration and development of stratigraphically trapped hydrocarbons requires detailed knowledge of the morphologies and reservoir characteristics of the stratigraphic body. Fluvial distributary channels are important exploration targets because they are typically isolated reservoirs, laterally and vertically sealed by delta plain and abandoned channel mudstone, and thus form excellent stratigraphic traps. The morphology and reservoir characteristics of fluvial distributary channels have been confused with fluvial channels in the past. Knowing the characteristics of fluvial distributary channels and their difference from fluvial channels is the key to the successful exploration and development of distributary channel reservoirs.Fluvial distributary channels, formed by mixed-load systems, are commonly rectilinear channel segments found only on the delta plain between the head of passes and the depositional mouthbars. While fluvial channel reservoirs are mainly sandstone deposits of meander pointbars or braided sheets, fluvial distributary channel reservoirs are typically elongated sandy channel sidebars attached to morphologically rectilinear channel walls. The sidebars form by both lateral and downstream accretion resulting from flow in a confined, but lowsinuosity thalweg, which may be filled with organic mud following channel abandonment. On 3D seismic data the morphology of a fluvial distributary channel is often slightly sinuous and can easily be mistaken for part of a meander channel belt.Fluvial distributary channels are usually thinner and shallower compared to their updip fluvial channel belts. Width-thickness ratios for fluvial distributary channel reservoirs are on average 50:1 (range 15:1 to 100:1), while meandering fluvial channel reservoirs have widththickness ratios typically >100:1, and braided river reservoirs show ratios of 500:1 or higher. Examples from the Mahakam Delta are used to illustrate these issues. Implications for exploration and development of deltaic deposits on the North West Shelf of Australia are discussed.
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Lotsari, Eliisa S., Mikel Calle, Gerardo Benito, Antero Kukko, Harri Kaartinen, Juha Hyyppä, Hannu Hyyppä, and Petteri Alho. "Topographical change caused by moderate and small floods in a gravel bed ephemeral river – a depth-averaged morphodynamic simulation approach." Earth Surface Dynamics 6, no. 1 (March 5, 2018): 163–85. http://dx.doi.org/10.5194/esurf-6-163-2018.
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Abstract. In ephemeral rivers, channel morphology represents a snapshot at the end of a succession of geomorphic changes caused by floods. In most cases, the channel shape and bedform migration during different phases of a flood hydrograph cannot be identified from field evidence. This paper analyses the timing of riverbed erosion and deposition of a gravel bed ephemeral river channel (Rambla de la Viuda, Spain) during consecutive and moderate- (March 2013) and low-magnitude (May 2013) discharge events, by applying a morphodynamic model (Delft3D) calibrated with pre- and post-event surveys by RTK-GPS points and mobile laser scanning. The study reach is mainly depositional and all bedload sediment supplied from adjacent upstream areas is trapped in the study segment forming gravel lobes. Therefore, estimates of total bedload sediment mass balance can be obtained from pre- and post-field survey for each flood event. The spatially varying grain size data and transport equations were the most important factors for model calibration, in addition to flow discharge. The channel acted as a braided channel during the lower flows of the two discharge events, but when bars were submerged in the high discharges of May 2013, the high fluid forces followed a meandering river planform. The model results showed that erosion and deposition were in total greater during the long-lasting receding phase than during the rising phase of the flood hydrographs. In the case of the moderate-magnitude discharge event, deposition and erosion peaks were predicted to occur at the beginning of the hydrograph, whereas deposition dominated throughout the event. Conversely, the low-magnitude discharge event only experienced the peak of channel changes after the discharge peak. Thus, both type of discharge events highlight the importance of receding phase for this type of gravel bed ephemeral river channel.
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Werther, Lukas, Tanja Menn, Johannes Schmidt, and Hartmut Müller. "Modelling pre-modern flow distances of inland waterways – a GIS study in southern Germany." Virtual Archaeology Review 12, no. 25 (July 14, 2021): 42. http://dx.doi.org/10.4995/var.2021.15245.
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<p class="VARAbstract">Rivers form major traffic arteries in pre-modern Central Europe and accurate regional to supra-regional network models of inland navigation are crucial for economic history. However, navigation distances have hitherto been based on modern flow distances, which could be a significant source of error due to modern changes in flow distance and channel pattern. Here, we use a systematic comparison of vectorized old maps, which enlighten the fluvial landscape before most of the large-scale river engineering took place, and modern opensource geodata to deduce change ratios of flow distance and channel patterns. The river courses have been vectorised, edited and divided into comparable grid units. Based on the thalweg, meandering and braided/anabranching river sections have been identified and various ratios have been calculated in order to detect changes in length and channel patterns. Our large-scale analytical approach and Geographic Information System (GIS) workflow are transferable to other rivers in order to deduce change ratios on a European scale. The 19<sup>th</sup> century flow distance is suitable to model pre-modern navigation distances. As a case study, we have used our approach to reconstruct changes of flow pattern, flow distance and subsequent changes in navigation distance and transportation time for the rivers Altmühl, Danube, Main, Regnitz, Rednitz, Franconian and Swabian Rezat (Southern Germany). The change ratio is rather heterogeneous with length and travel time changes of the main channel up to 24% and an extensive transformation of channel morphology in many river sections. Based on published travel time data, we have modelled the effect of our change ratios. Shipping between the commercial hubs Ulm and Regensburg, to give an example, was up to 5 days longer based on pre-modern distances. This is highly significant and underlines the necessity for river-specific correction values to model supra-regional networks of pre-modern inland waterways and navigation with higher precision.</p><p>Highlights:</p><ul><li><p>Systematic comparison of old maps and modern geodata to deduce river-specific length correction values to improve supra-regional network models of pre-modern inland navigation.</p></li><li><p>Large-scale analytical approach and transferable GIS workflow for flow distance reconstruction with case studies in Southern Germany.</p></li><li><p>Length changes of navigated fairways result in pre-modern period travel times up to 24% higher in corrected models.</p></li></ul>
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Karpeta, W. P. "Sedimentology and gravel bar morphology in an Archaean braided river sequence: the Witpan Conglomerate Member (Witwatersrand Supergroup) in the Welkom Goldfield, South Africa." Geological Society, London, Special Publications 75, no. 1 (1993): 369–88. http://dx.doi.org/10.1144/gsl.sp.1993.075.01.21.
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Ewert-Krzemieniewska, Aleksandra. "Kame or Moraine? A Sedimentological Study of a Glaciomarginal Landform at Niedźwiedziny (Great Polish Lowland)." Geologos 20, no. 3 (October 23, 2014): 167–81. http://dx.doi.org/10.2478/logos-2014-0013.
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Abstract A sedimentary succession in a gravel pit at Niedźwiedziny was investigated in order to determine its origin: kame or moraine. The gravel pit is located in an isolated hill of approx. 600 m long and 250–400 m wide. The succession is built of glaciofuvial deposits: a sandy/gravelly unit in the lower and middle parts, overlain by diam-icton. Five lithofacies have been distinguished, which represent two facies associations: (1) a fuvial association evolving from a high-energy to a transitional to a shallow braided river on an alluvial fan, and (2) an association of cohesive deposits representing a glacigenic mass fow. The interpretation is based mainly on palaeocurrent data and differs from conclusions by earlier investigators. The ice-marginal zone is characterised by a large variety of glaciomarginal forms. Their sedimentology, morphology and palaeogeography are determined by successive phases of deglaciation. The results of the present study show that the character of the deglaciation in the study area changed with time from frontal to areal deglaciation.
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IELPI, ALESSANDRO. "Lateral accretion of modern unvegetated rivers: remotely sensed fluvial–aeolian morphodynamics and perspectives on the Precambrian rock record." Geological Magazine 154, no. 3 (May 12, 2016): 609–24. http://dx.doi.org/10.1017/s001675681600025x.
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AbstractModern unvegetated rivers flowing through aeolian-dune fields demonstrate potential as analogues for pre-vegetation fluvial landscapes. A prominent example is contained in the Lençóis Maranhenses of Brazil, a coastal aeolian system hosting the semi-perennial Rio Negro. Remotely sensed images covering c. 45 years display the rhythmic expansion and wind-driven shift of single-threaded and sinuous fluvial trunks alternating with wider braided plains. Sinuous tracts feature mid-channel and bank-attached bars, including expansional point bars with subdued relief. The morphology, accretion and sediment transport of unvegetated point bars in the Rio Negro are compared to the morphodynamics of vegetated meandering rivers. Unvegetated point bars are composed of large coalescent unit bars, lack apparent scroll topography and are preferentially attached to channel banks located on the windward side of the river course. Unvegetated meanders have expansional behaviour related to downwind channel trailing. Point bars maintain an expansional planform despite spatial confinement induced by aeolian dunes. Channel-flow impingement onto cohesion-less banks favours scouring of deep pools along the bar tails, which host bank-collapse deposits subsequently reworked into new bars. Analogies to Precambrian rivers suggest that ancient unvegetated fluvial landscapes were not unequivocally featured by low sinuosity, especially if characterized by a low gradient and stable discharge. This inference is supported by ongoing studies on Proterozoic fluvial–aeolian systems in the Canadian Shield. Lack of scroll topography introduces overlap with low-sinuosity fluvial facies models, underscoring the value of observing ancient fluvial deposits in planform, or along 3D sections where the palaeodrainage of channel bodies and attached bars can be compared.
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Goździk, Jan, and Tomasz Zieliński. "Evolution of Early Pleistocene fluvial systems in central Poland prior to the first ice sheet advance – a case study from the Bełchatów lignite mine." Geologos 23, no. 2 (June 27, 2017): 89–107. http://dx.doi.org/10.1515/logos-2017-0011.
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AbstractDeposits formed between the Neogene/Pleistocene transition and into the Early Pleistocene have been studied, mainly on the basis of drillings and at rare, small outcrops in the lowland part of Polish territory. At the Bełchatów lignite mine (Kleszczów Graben, central Poland), one of the largest opencast pits in Europe, strata of this age have long been exposed in extensive outcrops. The present paper is based on our field studies and laboratory analyses, as well as on research data presented by other authors. For that reason, it can be seen as an overview of current knowledge of lowermost Pleistocene deposits at Bełchatów, where exploitation of the Quaternary overburden has just been completed. The results of cartographic work, sedimentological, mineralogical and palynological analyses as well as assessment of sand grain morphology have been considered. All of these studies have allowed the distinction of three Lower Pleistocene series, i.e., the Łękińsko, Faustynów and Krzaki series. These were laid down in fluvial environments between the end of the Pliocene up to the advance of the first Scandinavian ice sheet on central Poland. The following environmental features have been interpreted: phases of river incision and aggradation, changes of river channel patterns, source sediments for alluvia, rates of aeolian supply to rivers and roles of fluvial systems in morphological and geological development of the area. The two older series studied, i.e., Łękińsko and Faustynów, share common characteristics. They were formed by sinuous rivers in boreal forest and open forest environments. The Neogene substratum was the source of the alluvium. The younger series (Krzaki) formed mainly in a braided river setting, under conditions of progressive climatic cooling. Over time, a gradual increase of aeolian supply to the fluvial system can be noted; initially, silt and sand were laid down, followed by sand only during cold desert conditions. These fluvio-periglacial conditions are identified in the foreground of the advance of the oldest ice sheet into this part of central Poland. The series studied have been compared with other fluvial successions which accumulated in the Kleszczów Graben during subsequent glaciations so as to document general changes in fluvial systems as reactions to climatic evolution. Thus, a palaeoenvironmental scenario has emerged which could be considered to be characteristic of central Poland during the Early Pleistocene.
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Yang, Haiyan, and Peitong Cong. "Confluence Dynamics in a Modelled Large Sand-Bed Braided River." Water 11, no. 9 (September 3, 2019): 1829. http://dx.doi.org/10.3390/w11091829.
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Confluences are key morphological nodes in braided rivers where flow converges, creating complex flow patterns and rapid bed deformation. Field surveys and laboratory experiments have been carried out to investigate the morphodynamic features in individual confluences, but few have investigated the evolution processes of confluences in large braided rivers. In the current study, a physics-based numerical model was applied to simulate a large lowland braided river dominated by suspended sediment transport, and analyze the morphologic changes at confluences and their controlling factors. It was found that the confluences in large braided rivers exhibit some dynamic processes and geometric characteristics that are similar to those observed in individual confluences arising from two tributaries. However, they also show some unique characteristics that may result from the influence of the overall braided pattern and especially of their neighboring upstream channels.
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Zaremba, Małgorzata, Jerzy Trzciński, and Fabian Welc. "Holocene Lake Sediments as a Source of Building Material in Ancient Egypt; Archeometric Evidence from Wadi Tumilat (Nile Delta)." Studia Quaternaria 34, no. 2 (December 1, 2017): 109–18. http://dx.doi.org/10.1515/squa-2017-0009.
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Abstract The Tell el-Retaba archaeological site is located in the middle part of Wadi Tumilat, which extends along the north-eastern margin of the Nile Delta. It contains fragments of fortified and domestic objects of the ancient fortress and other constructions built of mud bricks. The establishment and functioning of the fortress is dated at the times of the reign of two great pharaohs, Ramesses II and Ramesses III (13th and 12th centuries BC). The grain size composition of the sediments used for mud brick production had significant influence on their physical and mechanical properties, which was used by the ancient Egyptians for the improvement of bricks. The finest fractions, clay and silt, which generally comprise clay minerals and organic matter played a significant role. These components significantly influenced the mud brick properties and resulted in a structural cohesion of the material. The second important component of mud bricks were coarse fractions – sand and gravel. The source of material used for brick production were the natural sediments located in the vicinity of the fortress, i.e. the Holocene lake clay and the Pleistocene gravel and sand of the gezira formation, deposited by a braided river. Clay sediments have a variable lithology as can be deduced from grain size composition of mud bricks and their properties. This variability was caused by a variable regime of the Nile, which supplied material to the lake basin. Geological studies were used to recognize ancient environment and morphology of the area, and to find clay, sand and gravel open-pits that existed in the area. The fortress site was selected optimally in relation to the landscape morphology and close vicinity of the source of basic material and water used for mud brick production. The area around the fortress was substantially transformed by humans due to settlement.
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Proust, Jean-Noël, Mathieu Renault, Pol Guennoc, and Isabelle Thinon. "Sedimentary architecture of the Loire River drowned valleys of the French Atlantic shelf." Bulletin de la Société Géologique de France 181, no. 2 (March 1, 2010): 129–49. http://dx.doi.org/10.2113/gssgfbull.181.2.129.
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Abstract The analysis of a dense grid of high resolution seismic profiles collected offshore the present day Loire River estuary indicates the presence of a thick and complex Pleistocene coastal wedge between the coast and 50 meters water depth. Most of this coastal wedge is preserved in a fossil valley network starting 10 km off the coast on the “Precontinent Breton” topographies and wedging out progressively 50 km in the offshore where the shelf flattens. This system is comprised of three main valleys 30 km long, 40–60 m deep and 0.7 to 4 km wide each, in average, with a northern valley incompletely filled by sediment. These valleys are incised into Eocene (Ypresian-Bartonian) sedimentary rocks lying unconformably on the metamorphic and magmatic rocks of the South Armorican Massif basement. The coastal wedge is comprised of six seismic units. From the base of the valleys to the seafloor, these units are successively interpreted as (1) colluvial (U1) and braided river deposits (U2), overlain by restricted marine to estuarine sediments (U3), and (2) straight to meandering fluvial deposits (U4) giving rise vertically to floodout marine sediments (U5). The whole sediment pile is capped by open marine bioturbated mudstones (U6). This succession of seismic units is organised in two depositional sequences bounded by an unconformity of regional extent, which corresponds to a drastic change in the paleovalley fill architecture. The lower sequence fills up the southern and central valleys when the upper sequence fills up the northern valley network. Both sequences are sharply truncated by a ravinement surface at the base of the offshore shales formed during the Holocene marine transgression. The correlation of the observed depth of the incisions and transgression surfaces with the global sea-level curve provides an indirect estimate of the ages of the depositional sequences. The lower sequence is probably Saalian (130–200 Ka, MIS 6) and the upper one Weischelian (110–12 Ka, MIS 2–4 and 5a–d). The ages and the infill of these valleys are very close to the ones observed in the largest paleovalleys of the inner French Atlantic shelf (Gironde, English Channel) and consistent with the sedimentary record of the continental Loire River (stepped terraces). In the later case, the Saalian period corresponds to a sharp increase on the incision of the river that shaped the morphology and determined the location of the present-day Loire valley.
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Gaurav, K., F. Métivier, O. Devauchelle, R. Sinha, H. Chauvet, M. Houssais, and H. Bouquerel. "Morphology of the Kosi megafan channels." Earth Surface Dynamics Discussions 2, no. 2 (October 1, 2014): 1023–46. http://dx.doi.org/10.5194/esurfd-2-1023-2014.
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Abstract. We study the morphology of streams flowing on the alluvial megafan of the Kosi River in north Bihar, India. All streams develop on a uniform sandy sediment and under a similar climate, allowing for statistically significant comparisons. Our data set includes both channels from the braid of the Kosi River and channels from isolated single-thread rivers. Using an Acoustic Doppler Current Profiler, we measure the width, depth and water discharge of the channels. Their average slope is also acquired with a kinematic GPS. These morphological characteristics are strongly correlated with the discharge. However, rescaling the data according to the threshold channel theory removes most of this dependency. The rescaled data suggest that the threads of the Kosi River braid are morphologically similar to isolated channels.
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Chalov, Roman S., Konstantin M. Berkovitch, Svetlana N. Ruleva, Aleksandr S. Zavadskiy, Pavel P. Golovlev, and Georgiy B. Golubcov. "FORMATION AND EVOLUTION OF PARALLEL-BRAIDED CHANNEL REACHES." Географический вестник = Geographical bulletin, no. 4(55) (2020): 110–25. http://dx.doi.org/10.17072/2079-7877-2020-4-110-125.
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The paper provides a comprehensive assessment of channel formation conditions and hydrological-morphological characteristics, and also considers the features of the channel changes regime of parallel-braided channel reaches, being the most complex and diverse in morphodynamics. The general condition for their development is a large width of channels (respectively, the maximum value of the criterion of the flow quasi-uniformity suggested by I.F. Karasev). In such channels, the flow is divided into two branches, between which, in the middle of the channel, occurs accumulation of sediments and formation of mid-channel bars and islands. At the same time, parallel-braided channels are the result of other channel types (non-meandering) development due to certain changes in determining factors: increased water content and sediment runoff, overgrowth of channel bars, as a result of which mid-channel bars turn into islands, and anthropogenic impacts on rivers. On sandy floodplain rivers, parallel-braided reaches are typical for low-stable and unstable channels in the absence of the directed influence from bedrock banks on the flow and when effective water discharge passes over the floodplain edge. The islands in such braided reaches are mostly small. On rivers with incised channels, they are either similar in morphology and the channel changes regime to wide floodplain unstable channels, differing from the latter in large islands with elongated shape, or form sculptural islands and are very stable. In any variety, parallel-braided channels are very individual in their channel changes regime and there are no universal channel control schemes for them.
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Hoey, Trevor B., and Alex J. Sutherland. "Channel morphology and bedload pulses in braided rivers: a laboratory study." Earth Surface Processes and Landforms 16, no. 5 (August 1991): 447–62. http://dx.doi.org/10.1002/esp.3290160506.
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Kasprak, Alan, Joseph M. Wheaton, Peter E. Ashmore, James W. Hensleigh, and Sarah Peirce. "The relationship between particle travel distance and channel morphology: Results from physical models of braided rivers." Journal of Geophysical Research: Earth Surface 120, no. 1 (January 2015): 55–74. http://dx.doi.org/10.1002/2014jf003310.
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Dhali, Md Kutubuddin, and Sutapa Mukhopadhyay. "Formation, Migration, and Morphodynamic Alteration of 50 Channel Bars in Darjeeling Himalayan Piedmont Zone, India." Air, Soil and Water Research 13 (January 2020): 117862212094143. http://dx.doi.org/10.1177/1178622120941436.
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Channel bars are common, striking fluvio-geomorphic depositional features of alluvial rivers. The study of this article has aimed to investigate the formation, migration, and morphodynamic alteration of channel bars (n = 50) in gravel braided alluvial rivers in Darjeeling Himalayan Piedmont zone. Dynamics of micro to meso bar deposition is mainly accomplished by the channel gradient, huge upstream landslide, and variation of discharge. Multi-criteria analysis method has been used to explain the variation of principal component analysis (PCA1, PCA2, and PCA3), both monsoon to post-monsoon. Bridge scouring, empirical aggradation, and degradation values are 0.1 to 1.05 m and [Formula: see text]. Migration, re-generation, and degradation of the micro bars with their optimum morphology show changes during the rainy season. In the upper ([Formula: see text]), middle ([Formula: see text]), and lower ([Formula: see text]) piedmont region, the bar dynamic area are 0.12 to 0.71, 0.12 to 2.83, and 0.10 to 5.43 km2, respectively. In total, 58% to 72% stability of the channel bars is observed in the upper piedmont region. The coefficient of determination ( R²) of channel bar area and width shows positive (0.63) relation.
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Redolfi, M., M. Tubino, W. Bertoldi, and J. Brasington. "Analysis of reach-scale elevation distribution in braided rivers: Definition of a new morphologic indicator and estimation of mean quantities." Water Resources Research 52, no. 8 (August 2016): 5951–70. http://dx.doi.org/10.1002/2015wr017918.
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Emery, Andy R., David M. Hodgson, Natasha L. M. Barlow, Jonathan L. Carrivick, Carol J. Cotterill, Janet C. Richardson, Ruza F. Ivanovic, and Claire L. Mellett. "Ice sheet and palaeoclimate controls on drainage network evolution: an example from Dogger Bank, North Sea." Earth Surface Dynamics 8, no. 4 (October 23, 2020): 869–91. http://dx.doi.org/10.5194/esurf-8-869-2020.
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Abstract. Submerged landscapes on continental shelves archive drainage networks formed during periods of sea-level lowstand. The evolution of these postglacial drainage networks also reveals how past climate changes affected the landscape. Ice-marginal and paraglacial drainage networks on low-relief topography are susceptible to reorganisation of water supply, forced by ice-marginal rearrangement, precipitation and temperature variations, and marine inundation. A rare geological archive of climate-driven landscape evolution during the transition from ice-marginal (ca. 23 ka) to a fully submerged marine environment (ca. 8 ka) is preserved at Dogger Bank, in the southern North Sea. In this study, our analysis of high-resolution seismic reflection and cone penetration test data reveal a channel network over a 1330 km2 area that incised glacial and proglacial lake-fill sediments. The channel network sits below coastal and shallow marine sediments and is therefore interpreted to represent a terrestrial drainage network. When mapped out, the channel form morphology reveals two distinct sets. The first set comprises two low-sinuosity, wide (>400 m) channels that contain macroforms of braid and side bars. These channels are interpreted to have originated as proglacial rivers, which drained the ice-sheet margin to the north. The second set of channels (75–200 m wide, with one larger, ∼400 m wide) has higher sinuosity and forms a subdendritic network of tributaries to the proglacial channels. The timing of channel formation lacks chronostratigraphic control. However, the proglacial rivers must have formed as the ice sheet was still on Dogger Bank, before 23 ka, to supply meltwater to the rivers. Ice-sheet retreat from Dogger Bank led to reorganisation of meltwater drainage and abandonment of the proglacial rivers. Palaeoclimate simulations show a cold and dry period at Dogger Bank between 23 and 17 ka. After 17 ka, precipitation increased, and drainage of precipitation formed the second set of channels. The second set of rivers remained active until marine transgression of Dogger Bank at ca. 8.5–8 ka. Overall, this study provides a detailed insight into the evolution of river networks across Dogger Bank and highlights the interplay between external (climate) and internal (local) forcings in drainage network evolution.
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Gao, Cunhai. "Ice-wedge casts in Late Wisconsinan glaciofluvial deposits, southern Ontario, Canada." Canadian Journal of Earth Sciences 42, no. 12 (December 1, 2005): 2117–26. http://dx.doi.org/10.1139/e05-072.
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Ice-wedge casts in Late Wisconsinan glaciofluvial sand and gravel deposits in southern Ontario taper downwards to form a V- or funnel-shaped morphology, ranging from 1 to over 3 m deep and from 1.0 to 2.5 m wide at the top. Pressure-derived primary structures, caused by repeated thermal contraction and expansion, include upturned strata, realigned stones, and small folds in the enclosing sediments. Although paleotemperature is difficult to estimate, the presence of ice-wedge casts testifies to the former presence of permafrost under prevailing periglacial conditions over this area. The regional till stratigraphy constrains the timing of ice-wedge growth to ca. 15 000 to ca. 13 000 BP. At this time, newly exposed terrains would have occurred in an interlobate area where severe climate created favourable conditions for permafrost to develop due to the close proximity to the receding ice. Inactive areas in braided rivers such as raised topographic surfaces and sand-filled channels with limited vegetation cover and minimal capability to trap drifting snow would have greatly enhanced ice-wedge growth. Rapid climatic amelioration and vegetation colonization across this area beginning ca. 13 000 BP probably slowed or stopped the growth of ice wedges. This limited window of opportunity, both geographically and in time, probably accounts for the limited occurrence of ice-wedge casts in southern Ontario.
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Hundey, E. J., and P. E. Ashmore. "Length scale of braided river morphology." Water Resources Research 45, no. 8 (August 2009). http://dx.doi.org/10.1029/2008wr007521.
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Kidová, Anna, Artur Radecki-Pawlik, Miloš Rusnák, and Karol Plesiński. "Hydromorphological evaluation of the river training impact on a multi-thread river system (Belá River, Carpathians, Slovakia)." Scientific Reports 11, no. 1 (March 18, 2021). http://dx.doi.org/10.1038/s41598-021-85805-2.
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AbstractThe paper evaluates the impact of river training works designed to address problems associated with flooding on the braided-wandering Belá River in Slovakian Carpathians. This impact was investigated after the flood event in July 2018 on 11 river reaches where the river engineering and management intervention was applied. We analyzed its impact by spatio-temporal variations in river morphology (12 channel parameters) and changes in cross-section and hydraulic parameters (flow velocity, shear stress, stream power, W/D ratio) between pre- and post-flood management periods. The research hypotheses related to decreasing geodiversity in managed river reaches, a rapid increase in flow velocity during an extreme flood in river reaches where there is no sufficient floodplain inundation due to artificially high banks built by river training works, and increasing erosive force in the channel zone thanks to river management intervention were confirmed. The intervention in the braidplain area of the Belá River resulted in an undesirable simplification of the river pattern, loss of geomorphic diversity, loss of channel–floodplain connectivity, and disturbance and restraint of hydromorphological continuity. Identification of main conflicts of the Belá River management is important for clarifying the different approaches of stakeholders in the study area and aims to provide an objective illustration of their consequences. The presented analyses could help in future management issues as well as in the more critical decision-making process in vulnerable and rare braided river systems on the present when we are losing so many natural rivers by human decisions.