Journal articles on the topic 'River channel profiles'
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1
Kosteniyk, Liudmyla, and Natalia Zablotovska. "FEATURES OF LEVEL PROCESSES ON MOUNTAIN RIVERS WITHIN THE BOUNDARIES OF THE VORKHTO-PUTYL LOW MOUNTAINS (CHEREMOSH BASIN)." SCIENTIFIC ISSUES OF TERNOPIL VOLODYMYR HNATIUK NATIONAL PEDAGOGICAL UNIVERSITY. SERIES: GEOGRAPHY 52, no. 1 (May 30, 2022): 51–59. http://dx.doi.org/10.25128/2519-4577.22.1.7.
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This publication is devoted to the study of the features of channel processes on mountain rivers that cross the Central synclinorium of the Ukrainian Carpathians, namely the region of the Vorokhto-Putilsky low mountains. These are mainly the rivers of the Cheremosh river basin, the hydrographic sources of the Black and White Cheremosh, as well as their small tributaries Iltsa and Richka.
It is within the boundaries of this geological and geomorphological region that atypical hollow expansions of the bottoms of river valleys are observed (Zhabeevskaya, Krivopilskaya, Iltsevskaya, Krivorivnesvkaya and Yablunetskaya).
According to the data of some researchers, the zone of the Vorokhto-Putyl low mountains is part of an older river runoff, the so-called Yasynya-Cheremoshskaya River, which is fragmentarily represented in the modern orography of the Ukrainian Carpathians and is currently not a homogeneous morphological structure. This old river, during the Pliocene period, had an internal flow into the basin of the Siret River, in the direction of its tributary, the Moldova River. It is in this zone that high terrace levels (VIII, IX) are well preserved, the direction of which does not correspond to modern river valleys.
The main feature of the channel processes of the rivers in this particular region is the disproportionate size of the bottoms of their valleys in accordance with the modern dimensions of the channels.
The second feature is the predominantly alluvial type of channels with a clearly expressed thick bottom pavement, as well as alluvial forms with well-rounded sediments.
An important modern element of modern scientific studies of channel processes is the measurement work in the channel to measure the depths of the river channel and the subsequent construction of the transverse profile of the river in certain key areas.
The results of these measurements, as well as the graphs of the transverse profiles themselves, are presented in this paper for the Iltsa, Chorny, and Bely Cheremosh rivers. A brief description of the features of the channel processes in the leveling areas is also given.
The obtained results make it possible to more reasonably and accurately analyze the flood zones of these rivers during the passage of floods and spring floods. And also, based on a comparison of the graphs of transverse profiles for different periods, it will be possible to more accurately assess the vertical deformations in different parts of the channels of the studied rivers.
Thus, for most riverbeds crossing the Vorokhta-Putilsky terraced lowlands, we see atypical hollow expansions of valley bottoms, which indicate local changes in geological and homorphological conditions in these areas, which in turn affects the formation of alluvial type of channels, with quite a large number of deposits of good run-in. This type of channel is more typical of rivers flowing within the foothills and more reminiscent of the free conditions of channel formation. At the same time, when moving to the area of the Skibov Carpathians, the incised type of channel becomes predominant again.
It should also be noted that the development of channel macroforms (incised macro-meanders on the rivers Iltsa, Chorny Cheremosh, Rivers) is observed within this lowland, which indicates a complex hierarchy of channel processes in this geomorphological zone.
Prospects for the use of results. The obtained results give the starting material for further, deeper, study and determination of the peculiarities of channel processes on the studied mountain rivers: due to the cross-sections it is possible to calculate the channel-forming water flow at given speeds and water levels; repeated leveling, after a certain period of time, will allow to estimate the intensity of vertical and planned deformations in the surveyed areas; it became possible to determine the zones of flooding during high floods by mathematical (calculation) methods, even in the absence of regular observations at the object of research and to estimate the coefficient of stability of the riverbed.
Key words: channel processes, mountain rivers, transverse profile, incised channel, vertical deformations
2
Wang, Yizhou, Liran Goren, Dewen Zheng, and Huiping Zhang. "Short communication: Forward and inverse analytic models relating river long profile to tectonic uplift history, assuming a nonlinear slope–erosion dependency." Earth Surface Dynamics 10, no. 4 (August 11, 2022): 833–49. http://dx.doi.org/10.5194/esurf-10-833-2022.
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Abstract. The long profile of rivers is shaped by the tectonic history that acted on the landscape. Faster uplift produces steeper channel segments, and knickpoints form in response to changes in the tectonic uplift rates. However, when the fluvial incision depends non-linearly on the river slope, as commonly expressed with a slope exponent of n≠1, the links between tectonic uplift rates and channel profile are complicated by channel dynamics that consume and form river segments. These non-linear dynamics hinder formal attempts to associate the form of channel profiles with the tectonic uplift history. Here, we derive an analytic model that explores a subset of the emergent non-linear dynamics relating to consuming channel segments and merging knickpoints. We find a criterion for knickpoint preservation and merging, and we develop a forward analytic model that resolves knickpoints and long profile evolution before and after knickpoint merging. We further develop a linear inverse scheme to infer tectonic uplift history from river profiles when all knickpoints are preserved. Application of the inverse scheme is demonstrated over the main trunks of the Dadu River basin that drains portions of the east Tibetan Plateau. The model infers two significant changes in the relative uplift rate history since the late Miocene that are compatible with low-temperature thermochronology. The analytic derivation and associated models provide a new framework to explore the links between tectonic uplift history and river profile evolution when the erosion rate and local slopes are non-linearly related.
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Brayall, M., and F. E. Hicks. "Applicability of 2-D modeling for forecasting ice jam flood levels in the Hay River Delta, Canada." Canadian Journal of Civil Engineering 39, no. 6 (June 2012): 701–12. http://dx.doi.org/10.1139/l2012-056.
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Ice jam floods can present an annual threat to communities adjacent to rivers, especially those situated at river confluences, island or deltas. The objective of this study was to determine whether 2-D modeling might be used to predict expected ice jam flood elevations for such multi-channel systems. The Hay River delta was selected as the demonstration site for this study, and 2-D modeling was employed to calculate ice jam flood levels expected for varying inflow discharge conditions. The River2D model was calibrated for historical ice jam profiles covering a range of discharges from 268 to 1000 m3/s and a relationship was developed to predict the flow split down the East and West Channels based on the inflow discharge to the delta. Also, ice jam rating curves were developed at 0.5 km intervals along each channel facilitating the development of an ice jam profile prediction tool for use by the Town of Hay River.
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Growns, Ivor, Iris Wing Tsoi, Mark Southwell, Sarah Mika, Sam Lewis, and Ben Vincent. "The effects of hydrology on macroinvertebrate traits in river channel and wetland habitats." Aquatic Ecosystem Health & Management 24, no. 4 (October 1, 2021): 93–102. http://dx.doi.org/10.14321/aehm.024.04.12.
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Abstract Increased need for freshwater for human uses from the mid-1900s has severely impacted rivers and floodplain wetlands so that they are some of the most seriously degraded environments in the world. Research and monitoring in this area to date has focused on understanding ‘flow-ecology’ relationships, without investigating the mechanisms underlying them. The use of species traits offers a tool for defining mechanistic connections between biotic responses and environmental conditions. We examined nine macroinvertebrate trait categories in both wetlands and channels to determine whether their profiles responded to hydrology in the Gwydir River system in the northern Murray-Darling Basin, Australia. Trait responses were shown for the wetlands but not the river channels. Twelve traits showed positive relationships with the time the wetlands were connected to their river channels. It is unclear the reason(s) why the river channel invertebrate traits did not respond to hydrology. However, the use of environmental flows in the river systems may be important to other aspects of macroinvertebrate assemblages such as their role in food webs to support higher-order consumers.
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Fares, Y. R. "Transient bottom topography changes in alluvial streams." Canadian Journal of Civil Engineering 27, no. 2 (April 1, 2000): 309–18. http://dx.doi.org/10.1139/l99-063.
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The development of a quasi two-dimensional computational model for simulating the transient variations of bed topography profiles in alluvial river channels is reported. The formulation of the model is based on combining the longitudinal flow momentum with the continuity principle of the sediment bed load. The Engelund-Hansen formula is employed in estimating the total sediment bed load along the reach of a river channel. The lateral bed load contribution from the total load is calculated in the same way as in calculating the lateral secondary currents from the main flow velocities. The numerical scheme and the computational procedure used in the study are described in detail. The simulated bed level profiles are verified through comparisons with experimental and field measurements taken from case studies in the literature for different flow conditions, channel characteristics, and sediment properties. The correlation between flow discharge, bed load, boundary friction, and channel slope is discussed. On the basis of the reasonably good comparisons with field data, it may be deduced that the model can be used for predicting the bottom topography variations in river channels.Key words: meandering rivers, bottom topography, sediment transport, bed load, boundary roughness, field measurements, experimental data, computational modelling, finite difference method.
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Yulistiyanto, Bambang, Bambang Kironoto, Bangun Giarto, Mariatul Kiptiah, and Muhammad Lutfi Tantowi. "The Simplified of Suspended Sediment Measurement Method in Natural River (Case study of Kuning River in Yogyakarta, Indonesia)." Journal of the Civil Engineering Forum 5, no. 3 (September 18, 2019): 243. http://dx.doi.org/10.22146/jcef.47061.
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The accumulation of suspended sediment reduces the capacity in the river and deteriorates the water quality. Kuning River in Yogyakarta is one of the main rivers in Yogyakarta, Indonesia, which is currently facing the issue of suspended sediments. To reduce the effect of suspended sediment and determine a preventive measure, hence, it is necessary to study the characteristics of the suspended sediment flow. Therefore, this study aims to investigate the suspended sediment flow characteristics, i.e. the velocity, and the concentration profiles at specific points in the transverse direction of the channel as well as the correlation of the suspended sediment discharge. Thirty (30) profiles of velocity and suspended sediment concentration were measured at six different points along the Kuning River. Opcon probe was used to measure suspended sediment concentration, while the propeller current meter was used to measure mean point-velocity profiles. Results of this study show the suspended sediment discharge ratio, defined as are higher in the middle part of the channel than the one near the edge of the channel. The position of z/B where the values of 1 occurs at z/B = 0,19 and z/B = 0,75, which depend on the irregularity of the channel cross-sections. For practical purposes, the depth-averaged velocity and suspended sediment concentration can be determined from 1, 2 and/or 3 points measurement at y = 0,2D, 0,4D and 0,8D.
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B. Vishnu, Ardra Wilson. "Evaluation of Morphological Changes in the River Bharathapuzha Using DEM Images." International Journal of Current Microbiology and Applied Sciences 10, no. 12 (December 10, 2021): 304–9. http://dx.doi.org/10.20546/ijcmas.2021.1012.035.
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Rivers have been a subject of study by engineers and scientists who have been fascinated by their self-formed geometric shapes and their responses to changes in nature and human interference. Among various types of human interventions, indiscriminate extraction of sand and gravel is the most disastrous one, as it threatens the very existence of the riverine ecosystem. Bharatapuzha is a great victim of illegal sand mining. The mining activity is particularly very high in the stretch between Pattambi and Kuttippuram of Bharathapuzha river. The study was undertaken to assess the morphological changes utilising DEM imageries. The analysis and assessment of satellite imageries were carried out using the ArcGIS 10.3 software. The Elevation Profile add-in toolbar was utilised to create profile graphs by taking sections across the river course in ArcGIS and the morphological changes of the river were calculated by comparing the cross-section profiles for the time period 2000 to 2014. Profile graphs revealed an average change in river bed depth of 0.25 m and an average change of cross-sectional area of about 134.66 m2. The main cross-sectional changes in the river reach of Kuttippuram to Pattambi were channel deepening and channel widening.
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Kimiaghalam, Navid, Masoud Goharrokhi, and Shawn P. Clark. "Estimating cohesive sediment erosion and deposition rates in wide rivers." Canadian Journal of Civil Engineering 43, no. 2 (February 2016): 164–72. http://dx.doi.org/10.1139/cjce-2015-0361.
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Sediment erosion and deposition rates are two of the most important factors that influence fluvial geomorphology. Several experimental devices have been constructed to estimate cohesive sediment erosion rate. However, estimated erosion rates may not be reliable for large rivers due to limited soil sampling and a high dependency of cohesive sediment behaviour on several physical, mechanical, and electrochemical properties of the sediment and eroding fluid. A new methodology has been developed to estimate the erosion and deposition rate of wide rivers using in situ measurements. To test this methodology, an acoustic Doppler current profiler was used to collect bathymetry and velocity profiles over a study area along the Red River in Winnipeg, Canada. Sediment concentration profiles along an 8.5 km reach of the river were measured several times under different flow conditions. Finally, an advection–dispersion equation was numerically solved using measured and calculated streamwise dispersion coefficients, flow and channel characteristics to calculate net erosion and deposition over the study area. Moreover, an exponential relationship was obtained between the river discharge and longitudinal dispersion coefficient for the Red River.
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Li, Yanyan, Guishan Yang, Bing Li, Rongrong Wan, Weili Duan, and Zheng He. "Quantifying the effects of channel change on the discharge diversion of Jingjiang Three Outlets after the operation of the Three Gorges Dam." Hydrology Research 47, S1 (July 5, 2016): 161–74. http://dx.doi.org/10.2166/nh.2016.016.
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The Jingjiang Three Outlets (JTO) are the water-sediment connecting channels between the Yangtze River and the Dongting Lake. The discharge diversion of the JTO plays a dominant role in the flood control of the middle–lower Yangtze River, Dongting Lake evolution, and ecological environment. After the operation of the Three Gorges Dam (TGD), the river channels downstream experienced dramatic channel changes. To study the influences of the channel change on the discharge diversion, the authors analyzed the channel changes by water level–discharge rating curves and cross-sectional channel profiles in 1980–2014. Hence, changes in the water level with the same discharge and the decline of discharge diversion at the JTO were noted. Channel incision caused the water level with the same discharge to greatly decrease in the upper Jingjiang River. The water level with the same discharge significantly increased at the JTO as a result of the channel deposition. The channel changes contributed approximately 37.74% and 76.36%, respectively, to the amount and ratio of discharge diversion decreases after the TGD operation. The channel changes serve as the primary factor in facilitating the decrease in the discharge diversion ratio, but not the main factor for the decreased amount of the discharge diversion.
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Lawrence, Susan, James Grove, Peter Davies, Jodi Turnbull, Ian Rutherfurd, and Mark Macklin. "Historical dredge mining as a significant anthropomorphic agent in river systems: A case study from south-eastern Australia." Holocene 31, no. 7 (March 25, 2021): 1158–74. http://dx.doi.org/10.1177/09596836211003272.
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Bucket dredging to mine and extract gold and tin from rivers is a global industry that has had a range of negative effects on physical environments. These include the destruction of riparian soil profiles and structures, artificial channel straightening and loss of in-stream biodiversity. In this paper we evaluate the immediate effects and long-term consequences of bucket dredging on rivers in Victoria and New South Wales during the period 1900–1950. High quality historical sources on dredge mining are integrated with geospatial datasets, aerial imagery and geomorphological data to analyse the scale of the dredging industry, evidence for disturbance to river channels and floodplains and current land use in dredged areas. The study demonstrates that the environmental impact of dredging was altered but not reduced by anti-pollution regulations intended to control dredging. An assessment of river condition 70–100 years after dredge mining ceased indicates that floodplains and river channels continue to show the effects of dredging, including bank erosion, sediment slugs, compromised habitat and reduced agricultural productivity. These findings have significant implications for river and floodplain management.
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Wickert, Andrew D., and Taylor F. Schildgen. "Long-profile evolution of transport-limited gravel-bed rivers." Earth Surface Dynamics 7, no. 1 (January 10, 2019): 17–43. http://dx.doi.org/10.5194/esurf-7-17-2019.
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Abstract. Alluvial and transport-limited bedrock rivers constitute the majority of fluvial systems on Earth. Their long profiles hold clues to their present state and past evolution. We currently possess first-principles-based governing equations for flow, sediment transport, and channel morphodynamics in these systems, which we lack for detachment-limited bedrock rivers. Here we formally couple these equations for transport-limited gravel-bed river long-profile evolution. The result is a new predictive relationship whose functional form and parameters are grounded in theory and defined through experimental data. From this, we produce a power-law analytical solution and a finite-difference numerical solution to long-profile evolution. Steady-state channel concavity and steepness are diagnostic of external drivers: concavity decreases with increasing uplift rate, and steepness increases with an increasing sediment-to-water supply ratio. Constraining free parameters explains common observations of river form: to match observed channel concavities, gravel-sized sediments must weather and fine – typically rapidly – and valleys typically should widen gradually. To match the empirical square-root width–discharge scaling in equilibrium-width gravel-bed rivers, downstream fining must occur. The ability to assign a cause to such observations is the direct result of a deductive approach to developing equations for landscape evolution.
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Sullivan, Jessica, Joshua Grubb, Ronald Willis, Derek Boozer, Brooks Flickinger, and Christopher Eric Dixon. "Cohesive Channel Response to Watershed Urbanization: Insights from the Sand River, Aiken SC." Water 12, no. 12 (December 8, 2020): 3441. http://dx.doi.org/10.3390/w12123441.
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Stream channel degradation is among the most widely documented symptoms of urban stream syndrome arising from watershed urbanization. Nevertheless, our present understanding of space and time scales associated with channel response to urbanization is poorly constrained and largely limited to assessments of non-cohesive systems. The purpose of this study is to assess the evolution of a cohesive, ephemeral river channel in response to watershed urbanization. The assessment of historical images document the stable, pre-urbanized channel conditions from 1870 to 1930. Historical assessments revealed a 131% increase in urbanized watershed area from 1930 to 1992, and a minimal increase in urbanized extent from 1992 to 2012. A 2012 lidar dataset was used to generate the modern long-channel profile, to reconstruct cross-channel profiles observed in 2002, and to estimate the volume flux of sediment removed from the channel from 1930 to 1992, and from 1992 to 2012. The long-channel profile reveals incision of up to 35 m in response to urbanization from 1930 to 1992. Cross-channel profiles reveal incision and widening of 2.5 and 3 m, respectively, from 2002 to 2012. Volume flux estimates indicate erosion rates of 9000 m3/yr during the first 62 years of the study period, and a flux of 4000 m3/yr after installation of stormwater control measures in 1992. Collectively, our findings highlight a cohesive channel that has undergone substantial incision and widening at a rate of ~0.20 m/yr since 1930, and the channel continues to adjust. Hence, we contend that the channel has not yet attained a new equilibrium “shape” at 82 years after peak land use change within the watershed, and that the channel will continue to adjust its shape until this new balance is achieved.
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Finnegan, Noah J., Kiara N. Broudy, Alexander L. Nereson, Joshua J. Roering, Alexander L. Handwerger, and Georgina Bennett. "River channel width controls blocking by slow-moving landslides in California's Franciscan mélange." Earth Surface Dynamics 7, no. 3 (September 20, 2019): 879–94. http://dx.doi.org/10.5194/esurf-7-879-2019.
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Abstract. To explore the sensitivity of rivers to blocking from landslide debris, we exploit two similar geomorphic settings in California's Franciscan mélange where slow-moving landslides, often referred to as earthflows, impinge on river channels with drainage areas that differ by a factor of 30. Analysis of valley widths and river long profiles over ∼19 km of Alameda Creek (185 km2 drainage area) and Arroyo Hondo (200 km2 drainage area) in central California shows a very consistent picture in which earthflows that intersect these channels force tens of meters of gravel aggradation for kilometers upstream, leading to apparently long-lived sediment storage and channel burial at these sites. In contrast, over a ∼30 km section of the Eel River (5547 km2 drainage area), there are no knickpoints or aggradation upstream of locations where earthflows impinge on its channel. Hydraulic and hydrologic data from United States Geological Survey (USGS) gages on Arroyo Hondo and the Eel River, combined with measured size distributions of boulders input by landslides for both locations, suggest that landslide derived boulders are not mobile at either site during the largest floods (>2-year recurrence) with field-measured flow depths. We therefore argue that boulder transport capacity is an unlikely explanation for the observed difference in sensitivity to landslide inputs. At the same time, we find that earthflow fluxes per unit channel width are nearly identical for Oak Ridge earthflow on Arroyo Hondo, where evidence for blocking is clear, and for the Boulder Creek earthflow on the Eel River, where evidence for blocking is absent. These observations suggest that boulder supply is also an unlikely explanation for the observed morphological differences along the two rivers. Instead, we argue that the dramatically different sensitivity of the two locations to landslide blocking is related to differences in channel width relative to typical seasonal displacements of earthflows. A synthesis of seasonal earthflow displacements in the Franciscan mélange shows that the channel width of the Eel River is ∼5 times larger than the largest annual seasonal displacement. In contrast, during wet winters, earthflows are capable of crossing the entire channel width of Arroyo Hondo and Alameda Creek. In support of this interpretation, satellite imagery shows that immobile earthflow-derived boulders are generally confined to the edges of the channel on the Eel River. By contrast, immobile earthflow-derived boulders jam the entire channel on Arroyo Hondo. Our results imply that lower drainage area reaches of earthflow-dominated catchments may be particularly prone to blocking. By inhibiting the upstream propagation of base-level signals, valley-blocking earthflows may therefore promote the formation of so-called “relict topography”.
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Li, Yan Hong, and Li Quan Xie. "2-D CFD Model for Free Surface River Flow with Tilt Rigid Leave of Submerged Vegetation." Applied Mechanics and Materials 212-213 (October 2012): 332–35. http://dx.doi.org/10.4028/www.scientific.net/amm.212-213.332.
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Keywords: river flow; two-dimensional CFD model; velocity profile; submerged vegetation leave Abstract. River flow with submerged foliage vegetation in straight and rectangular cross-sectional channel is numerically simulated through a vertical two-dimensional CFD model. Tilt thin strips are assigned in river flow to mimic the configuration of vegetation leave. The free surface line and the vertical profiles of longitudinal velocity are presented. The vertical velocity profile differs from the well acknowledged logarithmic or semi-logarithmic law. The submerged leave canopy resist the flow through it and pilots the flow upward over it, resulting in a decreased velocity within the canopy and an increased velocity above the canopy. The velocity profiles within the leave canopy are impacted by the configurations of the leave.
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Wang, Yizhou, Huiping Zhang, Dewen Zheng, Jingxing Yu, Jianzhang Pang, and Yan Ma. "Coupling slope–area analysis, integral approach and statistic tests to steady-state bedrock river profile analysis." Earth Surface Dynamics 5, no. 1 (February 24, 2017): 145–60. http://dx.doi.org/10.5194/esurf-5-145-2017.
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Abstract. Slope–area analysis and the integral approach have both been widely used in stream profile analysis. The former is better at identifying changes in concavity indices but produces stream power parameters with high uncertainties relative to the integral approach. The latter is much better for calculating channel steepness. Limited work has been done to couple the advantages of the two methods and to remedy such drawbacks. Here we show the merit of the log-transformed slope–area plot to determine changes in concavities and then to identify colluvial, bedrock and alluvial channels along river profiles. Via the integral approach, we obtain bedrock channel concavity and steepness with high precision. In addition, we run bivariant linear regression statistic tests for the two methods to examine and eliminate serially correlated residuals because they may bias both the estimated value and the precision of stream power parameters. We finally suggest that the coupled process, integrating the advantages of both slope–area analysis and the integral approach, can be a more robust and capable method for bedrock river profile analysis.
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Sutarto, Tommy. "Stable cross-sectional dimensions for navigation channel in the estuary of Sangatta River, Indonesia." E3S Web of Conferences 325 (2021): 05003. http://dx.doi.org/10.1051/e3sconf/202132505003.
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The objectives of this study are: 1) to capture the existing condition of the river channel in Sangatta River estuary, including the bathymetry of the river bed, and the cross-sectional dimensions of the river, 2) to design a stable navigation channel in Sangatta River estuary that allows less maintenance dredging and improves navigability of the channel during a critical condition when the water level is at the lowest, and 3) to test the effectiveness of the stable cross section in term of the availability of navigable depth. This research is divided into five stages, namely: 1) preparatory stage and preliminary survey, 2) main surveys, 3) hydrological and hydraulic analysis, 4) waterway design, and 5) dredging plan. The hydraulic analysis also includes determining the water level and depth profiles before and after dredging. HEC-RAS software is used to simulate, for each month, the water level and depth profiles in the channel at a critical condition when the sea water level is at low water spring (LWS) coincides with the river flow of 50% probability of occurrence, Q50. A stable channel for Sangatta River estuary is characterized with a bed slope, S = 0.00015, a flow depth, D = 3.6 m, a bed width, b = 76.3 m and a sidewall slope, m = 1.5. The simulation results show that the stable cross sections of the river provide sufficient water depth for navigation, even during the critical condition.
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Mudd, Simon M., Fiona J. Clubb, Boris Gailleton, and Martin D. Hurst. "How concave are river channels?" Earth Surface Dynamics 6, no. 2 (June 22, 2018): 505–23. http://dx.doi.org/10.5194/esurf-6-505-2018.
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Abstract. For over a century, geomorphologists have attempted to unravel information about landscape evolution, and processes that drive it, using river profiles. Many studies have combined new topographic datasets with theoretical models of channel incision to infer erosion rates, identify rock types with different resistance to erosion, and detect potential regions of tectonic activity. The most common metric used to analyse river profile geometry is channel steepness, or ks. However, the calculation of channel steepness requires the normalisation of channel gradient by drainage area. This normalisation requires a power law exponent that is referred to as the channel concavity index. Despite the concavity index being crucial in determining channel steepness, it is challenging to constrain. In this contribution, we compare both slope–area methods for calculating the concavity index and methods based on integrating drainage area along the length of the channel, using so-called “chi” (χ) analysis. We present a new χ-based method which directly compares χ values of tributary nodes to those on the main stem; this method allows us to constrain the concavity index in transient landscapes without assuming a linear relationship between χ and elevation. Patterns of the concavity index have been linked to the ratio of the area and slope exponents of the stream power incision model (m∕n); we therefore construct simple numerical models obeying detachment-limited stream power and test the different methods against simulations with imposed m and n. We find that χ-based methods are better than slope–area methods at reproducing imposed m∕n ratios when our numerical landscapes are subject to either transient uplift or spatially varying uplift and fluvial erodibility. We also test our methods on several real landscapes, including sites with both lithological and structural heterogeneity, to provide examples of the methods' performance and limitations. These methods are made available in a new software package so that other workers can explore how the concavity index varies across diverse landscapes, with the aim to improve our understanding of the physics behind bedrock channel incision.
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Huguenard, Kimberly, Kris Bears, and Brandon Lieberthal. "Intermittency in Estuarine Turbulence: A Framework toward Limiting Bias in Microstructure Measurements." Journal of Atmospheric and Oceanic Technology 36, no. 10 (October 2019): 1917–32. http://dx.doi.org/10.1175/jtech-d-18-0220.1.
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AbstractIntermittent turbulence behavior has a number of implications for field sampling, namely, that if undersampled, it can result in over- or underestimates of turbulent kinetic energy (TKE) dissipation rates. Sampling thresholds and common distributions have previously been defined for oceanic environments, but estuaries remain relatively underrepresented. Utilizing vertical microstructure profilers is a robust way to directly measure TKE dissipation rates; however, microstructure sensors are delicate and conducting a limited number of profiles in a burst is desirable. In this work, a statistical framework is used to characterize intermittency in a partially mixed estuary. In particular, a multiple comparison test is proposed to evaluate the number of profiles required to sufficiently represent TKE dissipation averages. The technique is tested on a microstructure dataset from the Damariscotta River in Maine, which covers seasonal and fortnightly time scales. The Damariscotta River features a variety of bathymetric and channel complexities, which provide the opportunity to examine intermittency as it relates to different processes. Small-scale intermittency is prominent during stratified conditions in shallow locations as well as near channel-shoal morphology, channel bends, and constrictions.
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Benda, L., D. Miller, and J. Barquín. "Creating a catchment scale perspective for river restoration." Hydrology and Earth System Sciences 15, no. 9 (September 27, 2011): 2995–3015. http://dx.doi.org/10.5194/hess-15-2995-2011.
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Abstract. One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2), in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we used computer tools to examine the spatial patterns of fluvial landscapes that are associated with five domains of hydro-geomorphic processes and landforms. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to hillslope and valley topography, river network structure, and channel elevation profiles. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.
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Huyghe, Pascale, Michel Foata, Eric Deville, Georges Mascle, and Caramba Working Group. "Channel profiles through the active thrust front of the southern Barbados prism." Geology 32, no. 5 (May 1, 2004): 429–32. http://dx.doi.org/10.1130/g20000.1.
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Abstract Submarine channels of the Orinoco River were analyzed using high-quality, dense- coverage bathymetric and seismic data provided by a recent marine survey on the southern Barbados prism. Analysis of the syntectonic sediments on seismic profiles shows that the four to five frontmost structures show evidence of recent tectonic movement. Slope analysis of the major channels was performed. From their headwaters to domains of little or no active tectonics, the channels display <0.2% slope and form levees. Slope and incision increase gradually in domains of moderate tectonics, but deep canyons with ∼2% mean slope form where the channels cross the active frontal folds of the prism. Detailed correlation between the active structures, their geometry, and canyon slope suggest that systematic variations in channel gradient highlight variations in substrate uplift rate. Steep slopes induced by uplift accelerate sediment flow and enhance incision. Nonetheless, such slope analysis is subject to complications introduced by variations in sediment flux and transient erosional conditions.
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Melo, Rafael Roney Camara de, and José Roberto Gonçalves de Azevedo. "Dynamics of sedimentary Capibaribe River bed after deepening dredging." RBRH 21, no. 4 (October 24, 2016): 871–81. http://dx.doi.org/10.1590/2318-0331.01161603.
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ABSTRACT The growth of urban centers in the country are increasingly dependent on the adoption of new mobility options, and before this need was developed and initiated a project to build a river corridor passenger in a part of the Capibaribe River in the city of Recife-PE. For the implementation of a navigation channel deepening are needed dredging to define a geometry of the bed of the river compatible with the needs of ships that will traverse the channel. The monitoring of dredging is done with the constant bathymetric surveys where the information volumes of dredged sediments are removed, aiming to also check the temporal behavior of deposition and erosion processes. In this context, the work aimed to evaluate the geometry of the Capibaribe river bed after the deepening dredging, using data from bathymetric surveys at different times for making longitudinal and transverse profiles, and create digital models of depth to extract information about the deposition/aggradation or erosion/removing sediments and their respective volumes. Early Profile Capibaribe river showed mild slope and heterogeneity in the bottom of the form, especially after kilometer five, with trends of deposition/aggradation downstream of the confluence region with tax arising from the weir Apipucos and upstream of the winding sections in local enlargement of the cross section, and the amount of the fork located at kilometer nine. The scenarios after the dredging to deepen indicate places with predominance of erosion and other sedimentation processes. They compared the longitudinal and transverse profiles of two areas located in western shipping channel, one with 350 meters and over 1000 meters, where it was found that the area 1 to erosion/sediment removal exceeded sedimentation/aggradation, indicating the occurrence of dredging the interval between the two surveys linked to the natural processes. In the study area 2 the sedimentation/aggradation exceeded the removal/erosion, with a volume equivalent to 1 cm thickness. The aggradation occur homogeneously in the navigation channel, while erosion was located on the banks, more intensely on the right bank of the river.
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Ioana-Toroimac, Gabriela, Liliana Zaharia, Gianina Neculau, and Gabriel Minea. "Impact Of Channel Incision On Floods: A Case Study In The South-Eastern Subcarpathians (Romania)." GEOGRAPHY, ENVIRONMENT, SUSTAINABILITY 13, no. 2 (June 24, 2020): 17–24. http://dx.doi.org/10.24057/2071-9388-2019-177.
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Despite numerous researches on river channel incision, there are fewer studies on the impact of channel adjustments on floods. This paper aims to investigate channel adjustments and to analyse their impact on the frequency of floods by estimating the return period of the bankfull discharge of the Prahova River in the South-Eastern Subcarpathians (Romania). The study is based on the analysis of the maximum annual discharges and cross-section profiles of the Prahova River at Câmpina gauging station (1976–2015). To estimate the return period of the bankfull discharge, the log Pearson III distribution was used. Overall, the maximum depth and the cross-section area at the bankfull stage increased during the analysed period, indicating channel incision and lateral stability. The bankfull discharge of 1976 could be reached every year and the one of 2015 could occur almost every 5 years. Therefore, due to channel incision and increased channel capacity, overflowing the bankfull stage is a less frequent hazard on the Prahova River at Câmpina gauging station. River management appears to maintain this situation as no measure is taken to decrease channel incision.
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Sougnez, N., and V. Vanacker. "Spatial variability in channel and slope morphology within the Ardennes Massif, and its link with tectonics." Hydrology and Earth System Sciences Discussions 7, no. 5 (September 16, 2010): 6981–7006. http://dx.doi.org/10.5194/hessd-7-6981-2010.
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Abstract. Geomorphic processes that produce and transport sediment, and incise river valleys are complex; and often difficult to quantify over longer timescales of 103 to 105 years. Morphometric indices that describe the topography of hill slopes, valleys and river channels have commonly been used to compare morphological characteristics between catchments and to relate them to hydrological and erosion processes. This work focuses on a wide range of slope and river channel morphometric indices to study their behavior and strength in regions affected by low to moderate tectonic activity. We selected 10 catchments of about 150 to 250 km2 across the Ardennes Massif that cover various tectonic domains with uplift rates ranging from about 0.06 to 0.20 mm year−1 since mid-Pleistocene times. The morphometric analysis indicates that the slope and channel morphology of third-order catchments is not yet in topographic steady-state, and exhibits clear convexities in slope and river profiles. Our data indicate that the fluvial system is the main driver of topographic evolution and that the spatial pattern of uplift rates is reflected in the distribution of channel steepness and convexity. The spatial variation that we observe in slope and channel morphology between the 10 third-order catchments suggests that the response of the fluvial system was strongly diachronous, and that a transient signal of adjustment is migrating from the Meuse valley towards the Ardennian headwaters.
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Wang, Zhaoyin, Guo-An Yu, Gary Brierley, and Le Liu. "Stream networks and knickpoints in the Sanjiangyuan Region." Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation 42, no. 1 (January 1, 2010): 79–91. http://dx.doi.org/10.2478/v10060-008-0067-5.
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Stream networks and knickpoints in the Sanjiangyuan Region The source area of the Lancang (Mekong), Yangtze and Yellow rivers is named in Chinese Sanjiangyuan (source of three rivers). Geographical characteristics of these rivers, and various rivers at the margin of the Qinghai-Tibetan Plateau (Jialing, Minjiang, Dadu, Yalong and Jinsha) are summarized from field investigations along with digital elevation model (DEM) analyses and satellite images. Uplift of the Qinghai-Tibetan Plateau has resulted in an asymmetrical distribution of tributaries for stream networks at the margins of the plateau. Almost all tributaries join the trunk stream from the northwest. Three types of drainage network are evident: plume, nervation and dendritic. In general, plume networks have a large number of first order streams. Nervation networks have a main stream and parallel tributaries. Dentritic networks are characrterized by continuous bifurcation and have a branch-like appearance. Most stream networks in the Sanjiangyuan region are of the nervation type. Several large knickpoints are evident along the longitudinal profiles of the Yellow and Yangtze Rivers. Channel aggradation immediately upstream of these knickpoints marks a transition in river processes from vertical bed evolution (i.e. incision) to horizontal channel adjustment (and associated braided and anabranching channels).
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Warren, C. D., and D. Blakeway. "Geological investigations and proposed development of the Colonia Soto district, Tegucigalpa, Honduras." Geological Society, London, Engineering Geology Special Publications 4, no. 1 (1987): 475–84. http://dx.doi.org/10.1144/gsl.eng.1987.004.01.57.
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AbstractThe twin cities of Tegucigalpa and Comayaguela, Honduras are located within an intermontaine basin. The urban area is dissected by several rivers which converge to form the main River Choluteca, flowing northwards. The river channels follow tortuous courses dictated principally by accidents of geology. As a consequence of the variable rainfalls and hurricanes that periodically lash the Republic, and the previous lack of management, the channel profiles have generally attained unacceptable physical dimensions inside the urban perimeter with some sections showing signs of instability. To add to this, the absence of appropriate stormwater drainage systems within certain areas of the City has given rise to foundation problems associated with collapse settlement. This paper summarizes the geological investigations carried out in the Colonia Soto district of the City with a view to eliminating the present hazardous conditions, as related to the underlying geology, with recommendations being made for future development of the hillside.
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Grau Galofre, Anna, A. Mark Jellinek, Gordon R. Osinski, Michael Zanetti, and Antero Kukko. "Subglacial drainage patterns of Devon Island, Canada: detailed comparison of rivers and subglacial meltwater channels." Cryosphere 12, no. 4 (April 20, 2018): 1461–78. http://dx.doi.org/10.5194/tc-12-1461-2018.
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Abstract. Subglacial meltwater channels (N-channels) are attributed to erosion by meltwater in subglacial conduits. They exert a major control on meltwater accumulation at the base of ice sheets, serving as drainage pathways and modifying ice flow rates. The study of exposed relict subglacial channels offers a unique opportunity to characterize the geomorphologic fingerprint of subglacial erosion as well as study the structure and characteristics of ice sheet drainage systems. In this study we present detailed field and remote sensing observations of exposed subglacial meltwater channels in excellent preservation state on Devon Island (Canadian Arctic Archipelago). We characterize channel cross section, longitudinal profiles, and network morphologies and establish the spatial extent and distinctive characteristics of subglacial drainage systems. We use field-based GPS measurements of subglacial channel longitudinal profiles, along with stereo imagery-derived digital surface models (DSMs), and novel kinematic portable lidar data to establish a detailed characterization of subglacial channels in our field study area, including their distinction from rivers and other meltwater drainage systems. Subglacial channels typically cluster in groups of ∼10 channels and are oriented perpendicular to active or former ice margins. Although their overall direction generally follows topographic gradients, channels can be oblique to topographic gradients and have undulating longitudinal profiles. We also observe that the width of first-order tributaries is 1 to 2 orders of magnitude larger than in Devon Island river systems and approximately constant. Furthermore, our findings are consistent with theoretical expectations drawn from analyses of flow driven by gradients in effective water pressure related to variations in ice thickness. Our field and remote sensing observations represent the first high-resolution study of the subglacial geomorphology of the high Arctic, and provide quantitative and qualitative descriptions of subglacial channels that revisit well-established field identification guidelines. Distinguishing subglacial channels in topographic data is critical for understanding the emergence, geometry, and extent of channelized meltwater systems and their role in ice sheet drainage. The final aim of this study is to facilitate the identification of subglacial channel networks throughout the globe by using remote sensing techniques, which will improve the detection of these systems and help to build understanding of the underlying mechanics of subglacial channelized drainage.
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De Cortes, João Paulo S., Rafael de Fraga, Fabiano N. Pupim, and George L. Luvizotto. "A statistical-based reach scale classification for the lower Tapajós river channel, eastern Amazonia." Progress in Physical Geography: Earth and Environment 45, no. 4 (January 20, 2021): 600–620. http://dx.doi.org/10.1177/0309133320981550.
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The Tapajós river is among the largest rivers in the world and has been credited as the main affluent of the lower Amazon River. Geomorphological studies in the Tapajós commonly deal with evolutionary, hydrological, and sedimentological issues. Recently, important advances have been made in understanding the morphology and dynamics in the Tapajós, especially in the confluence zone near Santarém, eastern Amazonian Brazil. However, the lack of an independent channel classification system makes it difficult to integrate data obtained from different sources. This work presents a classification system for the lower Tapajós based on morphometric variables extracted from transversal profiles coupled with radar and optical remote sensing data. We used discriminant analysis of principal components for the first time in fluvial geomorphology to provide a clustering-based geomorphological classification, which is statistically supported. We propose a segmentation of the channel into three distinct sections referred to as narrower channel reach, higher ria reach, and lower ria reach. The results showed that the channel has a distinct morphological pattern in each of these reaches, which can also be observed by the variation along the longitudinal profile. Our findings showed that the most variable hydrological and sedimentological patterns are found in the lower ria reach, while the higher ria reach comprises a canyon-shaped, more stable part of the channel. We discuss the implications of this pattern on the ria’s evolution. The method developed here could be applied to other areas of the Amazon basin, where the lack of data and logistical difficulties carrying out fieldwork are common obstacles to large-scale investigations. The identified reaches are indended to be considered in the sample design of future works and in the formulation of water resources management strategies.
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Kiran, S., Upendra Kumar, and Amit Kumar Dey. "Three Dimensional Numerical Simulation of Vortex Structures in Barak River." Applied Mechanics and Materials 772 (July 2015): 120–24. http://dx.doi.org/10.4028/www.scientific.net/amm.772.120.
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Natural channel have complex three dimensional flow structures particularly at the outer bank cell due to the combined effects of secondary currents and higher velocity profiles. In this paper Computational fluid dynamics is used to study the meandering bend of the Barak River. Numerical modeling is done using Reynolds averaged continuity and Navier Stokes equation. These equations are solved by finite volume method. Appropriate representation of counter-rotating secondary flow in the channel bend requires both the suitable treatment of the free water surface and a turbulence model that can resolve the anisotropy of turbulence. Hence the volume of fluid method (VOF) was used to model the free surface and reynolds stress turbulence model (RSM) has been used to close the RANS equations. Higher velocity profiles were prominent at the outer bank. Skew induced stream wise vorticity was observed close to the outer bank which confirms the existence of corner induced secondary current. The vortices formed were found to be of Prandtl’s first kind.
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Sougnez, N., and V. Vanacker. "The topographic signature of Quaternary tectonic uplift in the Ardennes massif (Western Europe)." Hydrology and Earth System Sciences 15, no. 4 (April 4, 2011): 1095–107. http://dx.doi.org/10.5194/hess-15-1095-2011.
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Abstract. Geomorphic processes that produce and transport sediment, and incise river valleys are complex; and often difficult to quantify over longer timescales of 103 to 105 y. Morphometric indices that describe the topography of hill slopes, valleys and river channels have commonly been used to compare morphological characteristics between catchments and to relate them to hydrological and erosion processes. This study aims to analyze the link between tectonic uplift rates and landscape morphology based on slope and channel morphometric indexes. To achieve this objective, we selected 10 catchments of about 150 to 250 km2 across the Ardennes Massif (a Palaeozoic massif of NW Europe, principally located in Belgium) that cover various tectonic domains with uplift rates ranging from about 0.06 to 0.20 mm yr−1 since mid-Pleistocene times. The morphometric analysis indicates that the slope and channel morphology of third-order catchments is not yet in topographic steady-state, and exhibits clear convexities in slope and river profiles. Our analysis indicates that the fluvial system is the main driver of topographic evolution and that the spatial pattern of uplift rates is reflected in the distribution of channel steepness and convexity. The spatial variation that we observe in slope and channel morphology between the 10 third-order catchments suggests that the response of the fluvial system was strongly diachronic, and that a transient signal of adjustment is migrating from the Meuse valley towards the Ardennian headwaters.
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Majeed, Hayder Q., Ali M. Ghazal, and Basheer Al-Hadeethi. "Experimental and Numerical Study of Open Channel Flow with T-Section Artificial Bed Roughness." Mathematical Modelling of Engineering Problems 9, no. 6 (December 31, 2022): 1589–95. http://dx.doi.org/10.18280/mmep.090619.
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Experimental and numerical studies have been conducted on the effects of bed roughness elements such as cubic and T-section elements that are regularly half-channel arrayed on one side of the river on turbulent flow characteristics and bed erosion downstream of the roughness elements. The experimental study has been done for two types of bed roughness elements (cubic and T-section shape) to study the effect of these elements on the velocity profile downstream the elements with respect to different water flow discharges and water depths. A comparison between the cubic and T-section artificial bed roughness showed that the velocity profile downstream the T-section increased in smooth side from the river and decrease in the rough side from it compared with the case when a cubic artificial bed roughness is used. By comparing the results for the element shapes, it can be notices that the T-section bed roughness element more effective compared to cubic shape for both sides of the channel. The numerical method has been done using Computational Fluid Dynamic (CFD) method. A validation for the CFD model with the experimental study have been carried out for a specific flow discharge and water depth. The results indicated that the velocity distribution profiles downstream the bed roughness elements in both sides shown very good agreement for manning coefficients between the numerical and experimental studies. The range of errors between the experimental and numerical study have been calculated using Root Mean Square Error (RMSE) approach, which is found that the RMSE is approximately equal to 1 in case of cubic bed roughness and the RMSE is about 1.5 in case of T-section bed roughness for both smooth and rough sides. Furthermore, the influence of the velocity profile and the bed erosion downstream of the T-section element under the effect of tides have been investigated using the CFD method, which is commonly happened in Shat al-Arab south of Iraq. The results show that the tide of the flow has a reverse effect on the velocity profiles for both sides. Since the velocity profile downstream of bed roughness region increase in the rough side and decrease in the smooth side compared with the normal flow of the river.
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Lee, Chanjoo, Donggu Kim, Sungjung Kim, Un Ji, Jihyun Kim, and Dongwoo Ko. "Flow structure around an actual willow patch under different depth conditions." E3S Web of Conferences 40 (2018): 02049. http://dx.doi.org/10.1051/e3sconf/20184002049.
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Vegetation is one of the key factors in river management where environmental aspects as well as flood protection should be taken into consideration. Because of this, numerous studies have been done including experiments and hydrodynamic modelling. Because most of experimental studies were made in indoor laboratory flumes with artificial trees, there are still limitations in transfer of their result to actual channels. REC (River Experiment Center) of Korea has been operating three real-scale, nature-like outdoor experimental channels. In a straight channel, several 4x2 m actual willow patches were planted and have been grown last three years for studies on flow vegetation interaction. A set of intensive flow measurement was made around the first upstream willow patch using ADVs together with measurement of vegetation properties. The experiments were made under several different depth conditions simulating snow-melt and flash-flood. Distribution of flow around and through the patch was characterized along with vertical profiles. The results of the experiment enhance understanding on interaction of flow and actual vegetation in a natural channel and may also provide information on flow resistance used for hydrodynamic modelling and validation.
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Chen, Yongping, Ninglin Jiang, and Changkuan Zhang. "RIVERBED EVOLUTION OF YANGTZE ESTUARY AND ITS RESPONSE TO THE HYDRODYNAMIC CHANGES AT UPSTREAM." Coastal Engineering Proceedings 1, no. 33 (December 13, 2012): 92. http://dx.doi.org/10.9753/icce.v33.sediment.92.
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The riverbed evolution of upper part of Yangtze estuary, Chengtong reach, is analyzed by comparison of 6 sets of bathymetry data during 1977~2011. The significant changes of water depth profiles along 6 representative cross-sections indicate the reach is still in the process of development. In order to get a better understanding of the effect of river discharge at upstream on the riverbed evolution of Chengtong reach, a series of numerical experiments are implemented by specifying different river discharge conditions at the upper boundary. The corresponding discharge ratio at main sub-reaches is compared to reveal the response of the riverbed evolution to the hydrodynamic changes at upstream. The results show that with the increase of river discharge, the discharge ratio in the main channels of Fujiangsha sub-reach and Rugaosha sub-reach increases, but it changes to decrease when the upstream river discharge becomes very large; however, the discharge ratio in the main channel of Tongzhousha sub-reach always decreases with the increase of river discharge at upstream.
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Hamza, Vijith, V. Prasannakumar, and P. Pratheesh. "Modelling and interpretation of channel profile anomalies through stream length gradient (SL) indexes and GIS: A case study from the Vamanapuram River, Kerala, India." Environmental Research, Engineering and Management 75, no. 2 (September 3, 2019): 60–73. http://dx.doi.org/10.5755/j01.erem.75.2.21300.
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Longitudinal profile of the Vamanapuram River and its five major tributaries was characterized to detect anomalies in terms of knick points through the calculation of stream length gradient (SL) indexes. Longitudinal profiles show presence of knick points in different reaches, indicating changes from the graded smooth concave profile to ungraded convex profile. The ungraded profile segments were confirmed by high SL indexes having sudden changes in values than the adjacent segments and those exactly fitted with the ungraded profile segments. The SL anomaly index is capable of expressing the stream profile anomalies in terms of its severity and to classify the river segments into different orders of anomalies. Higher order SL anomalies are mostly in the midland and lower regions than the headwaters region and are in uniform lithology and are unrelated to the map-scale structural features present in the river basin. The present study points to differential effect of geological process in the middle and lower reaches of the watershed in which the tributaries responded more than the major river. Past seismic events in the region confirm the role of neotectonic processes, which might have influenced the streams by changing the graded base level. Detailed field investigations of the anomalous stream segments can help to identify and understand the imprints caused due to neotectonic activity.
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Chalov, Sergey, Vsevolod Moreido, Ekaterina Sharapova, Lyudmila Efimova, Vasyli Efimov, Mikhail Lychagin, and Nikolay Kasimov. "Hydrodynamic Controls of Particulate Metals Partitioning Along the Lower Selenga River—Main Tributary of The Lake Baikal." Water 12, no. 5 (May 9, 2020): 1345. http://dx.doi.org/10.3390/w12051345.
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In this study, the downstream effects of pollutants spreading due to hydromorphological gradients and associated changes in sediment transport conditions along the braided-meandering and deltaic distributary reach of a large river downstream section are discussed. We demonstrate the significance of hydrodynamic control for sediment-associated metal partitioning along the river. Typically, the downward decline of the sediment and metals spreading towards Lake Baikal is observed due to buffer effects in the delta. During peak flow, the longitudinal gradients in heavy metal concentration along the distributary delta reach are neglected due to higher concentrations delivered from the upper parts of the river. In particular, significant variations of heavy metal concentrations associated with the river depth are related to sediment concentration and flow velocity profiles. Various particulate metal behavior in silt-sand delta channels and the sand–gravel Selenga main stem emphasize the importance of near-bottom exchange for particles spreading with the river flow. Using empirically derived Rouse numbers, we found quantitative relationships between the ratio of particulate metals sorting throughout depth in a single river channel and the hydrodynamic conditions of sediment transport.
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LI, Y., Z. K. YAN, R. J. ZHOU, L. SVIRCHEV, H. B. LI, D. C. SU, L. YAN, et al. "SURFACE PROCESS AND FLUVIAL LANDFORM RESPONSE TO THE MS 8.0 WENCHUAN EARTHQUAKE, LONGMEN SHAN, CHINA." Journal of Earthquake and Tsunami 07, no. 05 (December 2013): 1350033. http://dx.doi.org/10.1142/s1793431113500334.
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The MS 8.0 Wenchuan earthquake of May 12, 2008, in the Longmen Shan mountain range area in China, led to two roughly parallel NE-trending thrust and strike-slip surface ruptures of the Beichuan, Pengguan, and the Xiaoyudong faults. Coseismic deformation changed the topographical gradient and produced massive landslides and debris flows, causing a corresponding response of the fluvial landforms. In this paper, based on data regarding the surface ruptures and changes to the topography and drainage resulting from the earthquake, the influence of the thrusting and strike-slipping on fluvial landforms and drainage are integrated and analyzed. The results are shown for the following five main aspects: (1) the strike-slipping driven by the earthquake caused the formation of new tectonic diversion points of river channels; (2) the thrusting driven by the earthquake caused the formation of new tectonic slope-break points in the river channel; (3) the strikes of the faults activated by the earthquake controlled the river channel direction; (4) the uplifting driven by the earthquake led to changes of riverbed gradient profiles and their base levels; and (5) exceptionally heavy rainfall after the earthquake initiated landslides, debris flows and floods, and will continue to be a hazard for several decades to come.
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Kryniecka, Klaudia, Artur Magnuszewski, and Artur Radecki-Pawlik. "Sentinel-1 Satellite Radar Images: A New Source of Information for Study of River Channel Dynamics on the Lower Vistula River, Poland." Remote Sensing 14, no. 5 (February 22, 2022): 1056. http://dx.doi.org/10.3390/rs14051056.
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The amount of sediments transported by a river is difficult to estimate, while this parameter could influence channel geometry. It is possible to derive the bedload transport rate per unit width of the river channel by measuring the migration distance of bedform profiles over time and thickness of bedload layer in motion. Other possible methods include instrumental measurements using bedload traps and empirical formulas. It is possible to use remote-sensing techniques to measure the dynamics of bedform movements and geometries. Landsat images and aerial photographs have been used for this. A new source of remote-sensing information is radar satellite images. Sentinel-1 images have a temporal resolution of 2–3 days and spatial resolution of 25 m at middle latitudes, which make them usable on large rivers. The research area is the 814–820 km reach of the Lower Vistula River, where seven alternate sandbars were selected. The bank lines of the sandbars were delineated on Sentinel-1 images sensed during two low-flow periods of 4 August–26 September 2018 and 1 July–31 August 2019, when discharges at low flow were similar. From water stage observations at gauges, water elevations were assigned to every bank line of the alternate sandbars. The following morphometric parameters were calculated: alternate sandbar centers, volumes and longitudinal profile. Average daily movement of the sandbars in the period 4 August 2018–1 July 2019 was calculated as 0.97 m·day−1. A similar alternate sandbar movement velocity was obtained from a study of Sentinel-2 optical satellite images and hydro-acoustic measurements on the Lower Vistula River. Having depth of bedload in motion and alternate sandbar shift velocities, it was possible to calculate the rate of bedload transport according to the Exner approach formula. Rate of bedload transport was estimated as qb = 0.027 kg·s−1·m−1. This study shows a novel use of Sentinel-1 images to study the 3D geometry and movement rate of sandbars.
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Uvarov, Anatoly I., and Lilia A. Pronina. "RESEARCH OF TECHNOLOGIES OF GEODESIC MONITORING OF BOTTOM DEFORMATIONS IN THE AREA OF LOCATION OF UNDERWATER TRANSITIONS OF MAIN PIPELINES." Vestnik SSUGT (Siberian State University of Geosystems and Technologies) 25, no. 3 (2020): 107–16. http://dx.doi.org/10.33764/2411-1759-2020-25-3-107-116.
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It is noted that as a result of the interaction of the geodynamic complex of the river with the environment, changes in the channel appear, which entail planned and high-altitude deformations of the water artery. Therefore, in the construction and operation of engineering structures, they must be taken into account. The study of channel deformations, mostly high-altitude, in the areas of construction or the location of existing structures is a very urgent task to ensure their stable, trouble-free operation. It is established that for the study of channel deformations, two of the most common technologies are used. The first is the technology of combining plans for channel surveys, and the second is the combination of transverse profiles of the river using hydraulic rams fixed by signs on the shore. The results of a study of the technology for determining channel deformations during their geodetic monitoring are presented. The accuracy of the image of the underwater relief on the plans is estimated. The influence of the errors of combining plans on the accuracy of determining quantitative strain gauges is investigated.
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Biron, Pascale M., Thomas Buffin-Bélanger, and Nancy Martel. "Mixing processes at an ice-covered river confluence." E3S Web of Conferences 40 (2018): 05037. http://dx.doi.org/10.1051/e3sconf/20184005037.
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River confluences are characterized by a complex mixing zone with three-dimensional turbulent structures, which can be affected by the presence of an ice cover during the winter. The objective of this study is to characterize the flow structure in the mixing zone at a medium-size (~ 40 m) river confluence with and without an ice cover. Detailed velocity profiles were collected under the ice along the mixing plane with an Acoustic Doppler Velocimeter. For the ice-free conditions, drone imagery was used to characterize the mixing layer structures for various flow stages. Results indicate that during the ice-free conditions, very large Kelvin-Helmholtz (KH) coherent structures are visible due to turbidity differences, and occupy up to 50% of the width of the parent channel. During winter, the ice cover affects velocity profiles by moving the highest velocities towards the center of the profiles. Large turbulent structures are visible in both the streamwise and lateral velocity components. The strong correlation between these velocity components indicates that KH vortices are the dominating coherent structures in the mixing zone. A spatio-temporal conceptual model is presented to illustrate the main differences on the three-dimensional flow structure at the river confluence with and without the ice cover.
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Beltaos, Spyros, Brian Burrell, and Sayed Ismail. "1991 ice jamming along the Saint John River: a case study." Canadian Journal of Civil Engineering 23, no. 2 (April 1, 1996): 381–94. http://dx.doi.org/10.1139/l96-043.
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During April 1991, major and damaging ice jams formed on the Saint John River at Dickey, Maine, and at Sainte-Anne-de-Madawaska, New Brunswick. Field investigations included the measurement of five water surface profiles along the ice jam at Sainte-Anne-de-Madawaska and of shear wall heights at both Dickey and Sainte-Anne-de-Madawaska after the jams had released. These measurements were supplemented by considerable information from local observers and data collection agencies. Following a description of freeze-up and winter conditions, and a chronology of 1991 breakup events, the available data were analyzed according to current ice jam theory. Using a simplified equilibrium analysis and taking into account discharge and channel characteristics, the 1991 Dickey ice jam thickness and water level were calculated and were in general agreement with observed values. In the case of the Sainte-Anne-de-Madawaska jam, sufficient data were obtained for application and calibration of the numerical model RIVJAM which determines the configuration of a jam in nonequilibrium reaches. This resulted in successful reproduction of a measured water profile along the jam and approximate prediction of jam thickness. Implications of the calibrated model coefficients are discussed. Key words: ice jams, flooding, modelling, water level profiles.
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Li, Jie, Junqiang Xia, Meirong Zhou, Shanshan Deng, and Zenghui Wang. "Channel geometry adjustments in response to hyperconcentrated floods in a braided reach of the Lower Yellow River." Progress in Physical Geography: Earth and Environment 42, no. 3 (June 2018): 352–68. http://dx.doi.org/10.1177/0309133318776492.
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Hyperconcentrated floods with more than 200–300 kg/m3 sediment concentrations often occur in the Lower Yellow River (LYR) during flood seasons, which leads to unique fluvial processes in the braided reach of the LYR. The investigation of channel geometry adjustments in response to hyperconcentrated floods can not only help to gain a better understanding of associated fluvial processes, but also is significant for making flood control strategies in the braided reach. In this study, pre- and post-flood bankfull channel dimensions in the braided reach were calculated based on the observed cross-sectional profiles in 15 years with the occurrence of hyperconcentrated flood events. Adjustments in channel geometry at section- and reach-scales were investigated, with several factors influencing adjustments in reach-scale channel geometry being analyzed. It indicates that the mean sediment transport rate was a key factor influencing the adjustment index, although pre-flood channel geometry and sediment deposition can also affect the index to some extent. An empirical relationship was developed between the characteristic parameter representing the pre- and post-flood channel geometries and mean sediment transport rate in hyperconcentrated floods. Eleven datasets were used to calibrate the parameters in the empirical relation, with the datasets in 1973, 1988, 1995, and 2002 verifying the relation. The calculated post-flood characteristic parameter of channel geometry using the empirical relation agreed well with observed data, and the proposed method can be used to predict the reach-scale adjustment of channel geometry during hyperconcentrated floods in alluvial rivers.
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Sjogren, D. B., and R. B. Rains. "Glaciofluvial erosional morphology and sediments of the Coronation–Spondin Scabland, east-central Alberta." Canadian Journal of Earth Sciences 32, no. 5 (May 1, 1995): 565–78. http://dx.doi.org/10.1139/e95-048.
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Spatially discontinuous meltwater channel networks on the Canadian Prairies are usually interpreted as having formed subaerially in front of the retreating Laurentide ice sheet. Evidence in the Coronation–Spondin scabland, east-central Alberta, supports an alternative formation by progressive channelization of a subglacial sheetflow of water. The scabland is an integrated channel network with varying degrees of anabranching, the channels having highly variable sizes, shapes, and orientations. Enhanced scour at some channel confluences reflects contemporaneous channel utilization. Channels also display convex-up, concave-up, and undulatory along-channel profiles, with some junctions at the same elevations. Longitudinal grooves in large-scale channels are associated with numerous boulder deposits. Residual hills, demarcated by channels, display composite and streamlined forms. Superimposed on residuals are erosional transverse bedforms, longitudinal grooves, and undulating surfaces that indicate submergence for all but the last phase of channelization. Glaciofluvial deposits are found as pendant bars on the distal end of some large, flat-topped residuals, or as mantles superimposed on some residuals. The scabland is interpreted to have formed as a waning, subglacial sheetflood diverted around hummocky terrain to the southwest. A rapidly subsiding ice roof, and instability in the flow, eventually concentrated meltwater into discrete channels. Abrupt cessation of flow left discontinuous gravel–boulder deposits, and ice sheet loading formed small-scale glaciotectonic features as the ice recoupled to its bed. Subsequent deglaciation barely modified the scabland, leaving it straddling part of the modern topographic divide between the Battle and Red Deer river basins.
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Stutenbecker, L. A., A. Costa, and F. Schlunegger. "Patterns of landscape form in the upper Rhône basin, Central Swiss Alps, predominantly show lithologic controls despite multiple glaciations and variations in rock uplift rates." Earth Surface Dynamics Discussions 3, no. 4 (October 2, 2015): 1061–105. http://dx.doi.org/10.5194/esurfd-3-1061-2015.
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Abstract. The development of topography is mainly dependent on the interplay of uplift and erosion, which are in term controlled by various factors including climate, glaciers, lithology, seismic activity and short-term variables such as anthropogenic impact. While most studies have focused on the role of tectonics and climate on the landscape form and underlying processes, less attention has been paid on exploring the controls of lithology on erosion. The Central European Alps are characterized by a large spatial variability in exposed lithologies and as such offer an ideal laboratory to investigate the lithological controls on erosion and landscape form. Here, we focus on the ca. 5400 km2-large upper Rhône basin situated in the Central Swiss Alps to explore how the lithological architecture of the bedrock conditions the Alpine landscape. To this extent, we extract geomorphological parameters along the channels of ca. 50 tributary basins, whose catchments are located in either granitic basement rocks (External massifs), oceanic meta-sedimentary and ophiolitic rocks (Penninic nappes) or fine-grained continental-margin sediments (Helvetic nappes). The analysis of longitudinal river profiles show that all tributary rivers within the Rhône basin are in topographic transient state as testified by mainly convex or concave-convex longitudinal stream channel profiles with several knickpoints of either tectonic or glacial origin. In addition, although the entire Rhône basin shows a strong glacial inheritance (and is still partly glaciated) and some of the highest uplift rates recently measured in the Alps, the river network has responded differently to those perturbations as revealed by the morphometric data. In particular, tributary basins in the Helvetic nappes are the most equilibrated (concave river profiles, overall lower elevations, less steep slope gradients and lowest hypsometric integrals), while the tributaries located in the External massifs are least equilibrated, where streams yield strong convex long profiles, and where the tributary basins have the highest hypsometric integral and reveal the steepest hillslopes. We interpret this pattern to reflect differences in response times of the fluvial erosion in tributary streams towards glacial and tectonic perturbations, where the corresponding lengths strongly depend on the lithology and therefore on the bedrock erodibility.
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Pradhan, Arpan, Kishanjit Kumar Khatua, and Sovan Sankalp. "Variation of Velocity Distribution in Rough Meandering Channels." Advances in Civil Engineering 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/1569271.
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Distribution of flow and velocity in a meandering river is important in river hydraulics to be investigated from a practical point of view in relation to the bank protection, navigation, water intakes, and sediment transport-depositional patterns. When flow enters a bend, the centrifugal force arising from the channel curvature leads to a transversal slope in the water surface. The interaction between the centrifugal force and transversal pressure gradient causes secondary flows in cross-sections, and the secondary flows spread further by moving along the bend. Hence, at the bends, these processes lead to longitudinal velocity increase in the inner wall and decrease at the outer wall. In this paper, experimentation is carried out for two different bed roughness on a 4.11 sinuosity meandering channel with 110° crossover. Longitudinal velocity distribution is analysed with the graphical illustrations for the detailed experimental study. Study of flow profile across the crossover is also particularly important as the inner bank of the bend changes to the outer bank and vice versa which has a significant effect on the water surface profile and hence on the velocity distribution along the full meander path. The objective of the analysis is to determine the effect of curvature and roughness on the velocity profiles, throughout the meander path. It is determined that the resistance of flow, on the smoother bed channel, is higher than that of the channel with higher Manning’s n above a certain depth at the apex and transition sections. A reciprocal study of the experimental investigation is attempted with a numerical hydrodynamic tool, namely, CCHE (Centre for Computational Hydroscience and Engineering) developed by NCCHE, University of Mississippi, US. The model is applied to simulate the inbank flow velocity distribution and validate the experimental observation for the meandering channel with rough bed.
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Robl, Jörg, Kurt Stüwe, and Stefan Hergarten. "Channel profiles around Himalayan river anticlines: Constraints on their formation from digital elevation model analysis." Tectonics 27, no. 3 (June 2008): n/a. http://dx.doi.org/10.1029/2007tc002215.
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Fan, Jinsheng, Heqing Huang, Guoan Yu, and Teng Su. "River Channel Forms in Relation to Bank Steepness: A Theoretical Investigation Using a Variational Analytical Method." Water 12, no. 5 (April 28, 2020): 1250. http://dx.doi.org/10.3390/w12051250.
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Riverbanks vary considerably in anti-scourability and consequently take various profiles. By using an isosceles trapezoid as the generalized form of river channel cross-sections and then incorporating the effects of bank angle into the variational analytical approach developed by Huang and Nanson (2000), this study presents a detailed theoretical investigation of the self-adjustment of alluvial channel forms. It is demonstrated that when alluvial channel flow achieves stable equilibrium, a significant decrease in riverbank steepness leads to a slight decrease in maximum sediment (bedload) discharge, and yet results in a significant increase in optimal channel width and a considerable decrease in optimal channel depth. The hydraulic geometry relations, theoretically derived for bank steepness to vary across a wide range, show that among the multivariant controls, the roles of bed sediment size, channel roughness, flow discharge and sediment (bedload) discharge are independent of bank steepness. While the effects of bank steepness illustrated in the theoretically derived hydraulic geometry relations are highly consistent with the results of threshold theory and previous empirical studies, limitations on using bank angle to reflect the anti-scourability of natural riverbanks are also highlighted.
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Hergarten, S., J. Robl, and K. Stüwe. "Tectonic geomorphology at small catchment sizes – extensions of the stream-power approach and the <i>χ</i> method." Earth Surface Dynamics 4, no. 1 (January 15, 2016): 1–9. http://dx.doi.org/10.5194/esurf-4-1-2016.
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Abstract. Quantitative tectonic geomorphology hinges on the analysis of longitudinal river profiles. The model behind almost all approaches in this field originates from an empirical relationship between channel slope and catchment size, often substantiated in the form of the stream-power model for fluvial incision. Significant methodological progress was recently achieved by introducing the χ transform. It defines a nonlinear length coordinate in such a way that the inherent curvature of river profiles due to the increase of catchment sizes in the downstream direction is removed from the analysis. However, the limitation to large catchment sizes inherited from the stream-power approach for fluvial incision persists. As a consequence, only a small fraction of all nodes of a digital elevation model (DEM) can be used for the analysis. In this study we present and discuss some empirically derived extensions of the stream power law towards small catchment sizes in order to overcome this limitation. Beyond this, we introduce a simple method for estimating the adjustable parameters in the original χ method as well as in our extended approaches. As a main result, an approach originally suggested for debris flow channels seems to be the best approximation if both large and small catchment sizes are included in the same analysis.
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Hergarten, S., J. Robl, and K. Stüwe. "Tectonic geomorphology at small catchment sizes – extensions of the stream-power approach and the χ method." Earth Surface Dynamics Discussions 3, no. 3 (August 17, 2015): 689–714. http://dx.doi.org/10.5194/esurfd-3-689-2015.
Full textAbstract:
Abstract. Quantitative tectonic geomorphology hinges on the analysis of longitudinal river profiles. The model behind almost all approaches in this field originates from an empirical relationship between channel slope and catchment size, often substantiated in form of the stream-power model for fluvial incision. A significant methodological progress was recently achieved by introducing the χ transform. It defines a nonlinear length coordinate in such a way that the inherent curvature of river profiles due to the increase of catchment sizes in downstream direction is removed from the analysis. However, the limitation to large catchment sizes inherited from the stream power approach for fluvial incision persists. As a consequence, only a small fraction of all nodes of a DEM can be used for the analysis. In this study we present and discuss some empirically derived extensions of the stream power law towards small catchment sizes in order to overcome this limitation. Beyond this, we introduce a simple method for estimating the adjustable parameters in the original χ method as well as in our extended approaches. As a main result, an approach originally suggested for debris flow channels seems to be the best approximation if both large and small catchment sizes are included in the same analysis.
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Montgomery, David R., and Tim B. Abbe. "Influence of logjam-formed hard points on the formation of valley-bottom landforms in an old-growth forest valley, Queets River, Washington, USA." Quaternary Research 65, no. 1 (January 2006): 147–55. http://dx.doi.org/10.1016/j.yqres.2005.10.003.
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AbstractField surveys and radiocarbon dating of buried logjams in the floodplain of an old-growth forest river demonstrate the formation of erosion-resistant “hard points” on the floodplain of the Queets River, Washington. These hard points provide refugia for development of old-growth forest patches in frequently disturbed riparian environments dominated by immature forest. Our surveys show that local bed aggradation associated with logjams not only influences channel patterns and profiles but leads to development of a patchwork of elevated landforms that can coalesce to form portions of the valley bottom with substantial (i.e., 1 to > 4 m) relief above the bankfull elevation. In addition, logjam-formed hard points promote channel avulsion, anastomosing morphology, and growth of mature patches of floodplain forest that, in turn, provide large logs needed to form more logjam-formed hard points. Hence, our findings substantiate the potential for a feedback mechanism through which hard points sustain complex channel morphology and a patchwork floodplain composed of variable-elevation surfaces. Conversely, such a feedback further implies that major changes in riparian forest characteristics associated with land use can lead to dramatic simplification in channel and floodplain morphology.
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Bujakowski, Filip, Tomasz Falkowski, and Anna Podlasek. "Geomorphological immaturity as a factor conditioning the dynamics of channel processes in Rządza River." Open Geosciences 13, no. 1 (January 1, 2021): 027–38. http://dx.doi.org/10.1515/geo-2020-0209.
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Abstract A major part of Poland, classified geographically as Polish Lowland, is covered by a layer of loose or cohesive sediments whose thickness increases toward the north. Numerous authors emphasize the impact of the protrusion of the erosional base level on the course of processes shaping modern river valleys. It has been demonstrated, among other things, that the culmination of the sub-alluvial, cohesive bedrock determines the manner in which the channel zone and the adjacent floodplain are formed, which is associated with the hydrological system of the river. A number (12) of geological documenting holes have been drilled to the bottom of the valley. Also, geological profiles were recorded for 34 natural outcrops. The range of the individual outcrops was determined using a geomorphological analysis based on, among other things, the data from airborne laser scanning. The main objective of the research based on geomorphological criteria was to identify the differences in valley morphology and geological structure as well as the dynamics of currently occurring fluvial processes, along with geological features influencing their development, in particular in the middle course of a river. The research allowed the distinction of three geologically and geomorphologically characteristic sections. This allowed an answer to the question: why is the river in the lowland similar to a mountain stream.
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Larson, James, Michelle Bartsch, Steve Gutreuter, Brent Knights, Lynn Bartsch, William Richardson, Jonathan Vallazza, and Michael Arts. "Differences between main-channel and off-channel food webs in the upper Mississippi River revealed by fatty acid profiles of consumers." Inland Waters 5, no. 2 (April 1, 2015): 101–6. http://dx.doi.org/10.5268/iw-5.2.781.
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