Journal articles: 'Channel morphology'

1

Wohl, Ellen E., and David M. Merritt. "Bedrock channel morphology." Geological Society of America Bulletin 113, no. 9 (September 2001): 1205–12. http://dx.doi.org/10.1130/0016-7606(2001)113<1205:bcm>2.0.co;2.

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Wu, Weiming, Lu Wang, Xudong Ma, Ruihua Nie, and Xingnian Liu. "Flow Characteristics and Bed Morphology in a Compound Channel between Two Single Channels." Water 12, no. 12 (December 16, 2020): 3544. http://dx.doi.org/10.3390/w12123544.

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In mountainous areas, a river can widen from a single channel to a compound channel under the influence of geological conditions or human impacts, bringing about challenges in terms of flood control and channel regulation. This paper reports the results of tests conducted in a 26 m long flume with a uniform sediment bed (grain size = 0.5 mm), investigating the flow characteristics and bed morphology in a compound channel between two single channels. The stage‒discharge relationship in the compound channel and the longitudinal and cross-sectional bed profile in the compound channel between two single channels are presented and analyzed. The experimental results indicate that the flow characteristics and bed morphology in a compound channel between two single channels are significantly different from those in a normal compound channel. Based on the experimental data and observations, the mechanisms of flow and sediment transport in the compound channel between two single channels are illuminated.

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Jeong, Won-Jeong, Ji-Ho Yoo, Tae-Hong Kim, Myung-Don Kim, Hyun-Kyu Chung, Seok-Hee Bae, and Jeong-Ki Pack. "MIMO Channel Modeling Using Concept of Path Morphology." Journal of Korean Institute of Electromagnetic Engineering and Science 21, no. 2 (February 28, 2010): 179–87. http://dx.doi.org/10.5515/kjkiees.2010.21.2.179.

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Gaurav, K., F. Métivier, O. Devauchelle, R. Sinha, H. Chauvet, M. Houssais, and H. Bouquerel. "Morphology of the Kosi megafan channels." Earth Surface Dynamics Discussions 2, no. 2 (October 1, 2014): 1023–46. http://dx.doi.org/10.5194/esurfd-2-1023-2014.

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Abstract. We study the morphology of streams flowing on the alluvial megafan of the Kosi River in north Bihar, India. All streams develop on a uniform sandy sediment and under a similar climate, allowing for statistically significant comparisons. Our data set includes both channels from the braid of the Kosi River and channels from isolated single-thread rivers. Using an Acoustic Doppler Current Profiler, we measure the width, depth and water discharge of the channels. Their average slope is also acquired with a kinematic GPS. These morphological characteristics are strongly correlated with the discharge. However, rescaling the data according to the threshold channel theory removes most of this dependency. The rescaled data suggest that the threads of the Kosi River braid are morphologically similar to isolated channels.

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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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Zhang, Ge, Bo Liu, Aiguo Xu, Yiming Shan, and Yingjun Li. "Morphology Effect of Surface Structures on Microchannel Flow Using Lattice Boltzmann Method." Geofluids 2019 (February 26, 2019): 1–14. http://dx.doi.org/10.1155/2019/3475872.

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Microchannel flow shows a fascinating background on a lot of engineering problems. In order to shed a light on the effect of the surface morphology of microchannels on fluid flow, differently shaped and arranged artificial elements constitute channels with different morphology and numerical simulation based on lattice Boltzmann method is conducted. The impact of micro effect is also stressed by comparing the results considering and not considering it in the same channel model. Analysis of flow details shows the difference of the morphology effect on fluid flow, which differs by the shape and density of the elements’ array. The permeability of channels shows a specific relationship with the density of artificial elements, and differences are found between varied shapes and the existence of micro effects. Further research is carried based on more complex channels with arrays of fractal-character artificial elements. As elements in the channel can be divided into main summits and subsummits, their different roles of the effect on the fluid flow is investigated. The result shows that the permeability will not change if main summits are kept in channels while all subsummits are removed to make a distinct simplification of the morphology. This discovery is furtherly ensured numerically by a test on a channel created with the profile of a rough rock surface. The finding for morphology effect on fluid flow can supply a reference for the prediction of the permeability of complex channels or fractures.

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Payenberg, T. H. D., and S. C. Lang. "RESERVOIR GEOMETRY OF FLUVIAL DISTRIBUTARY CHANNELS—IMPLICATIONS FOR NORTHWEST SHELF, AUSTRALIA, DELTAIC SUCCESSIONS." APPEA Journal 43, no. 1 (2003): 325. http://dx.doi.org/10.1071/aj02017.

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The exploration and development of stratigraphically trapped hydrocarbons requires detailed knowledge of the morphologies and reservoir characteristics of the stratigraphic body. Fluvial distributary channels are important exploration targets because they are typically isolated reservoirs, laterally and vertically sealed by delta plain and abandoned channel mudstone, and thus form excellent stratigraphic traps. The morphology and reservoir characteristics of fluvial distributary channels have been confused with fluvial channels in the past. Knowing the characteristics of fluvial distributary channels and their difference from fluvial channels is the key to the successful exploration and development of distributary channel reservoirs.Fluvial distributary channels, formed by mixed-load systems, are commonly rectilinear channel segments found only on the delta plain between the head of passes and the depositional mouthbars. While fluvial channel reservoirs are mainly sandstone deposits of meander pointbars or braided sheets, fluvial distributary channel reservoirs are typically elongated sandy channel sidebars attached to morphologically rectilinear channel walls. The sidebars form by both lateral and downstream accretion resulting from flow in a confined, but lowsinuosity thalweg, which may be filled with organic mud following channel abandonment. On 3D seismic data the morphology of a fluvial distributary channel is often slightly sinuous and can easily be mistaken for part of a meander channel belt.Fluvial distributary channels are usually thinner and shallower compared to their updip fluvial channel belts. Width-thickness ratios for fluvial distributary channel reservoirs are on average 50:1 (range 15:1 to 100:1), while meandering fluvial channel reservoirs have widththickness ratios typically >100:1, and braided river reservoirs show ratios of 500:1 or higher. Examples from the Mahakam Delta are used to illustrate these issues. Implications for exploration and development of deltaic deposits on the North West Shelf of Australia are discussed.

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8

Chang, Howard H. "River morphology and river channel changes." Transactions of Tianjin University 14, no. 4 (August 2008): 254–62. http://dx.doi.org/10.1007/s12209-008-0045-3.

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9

Best, James L. "The morphology of river channel confluences." Progress in Physical Geography: Earth and Environment 10, no. 2 (June 1986): 157–74. http://dx.doi.org/10.1177/030913338601000201.

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Heng, John E., David Zurakowski, Christian K. Vorwerk, Cynthia L. Grosskreutz, and Evan B. Dreyer. "Cation channel control of neurite morphology." Developmental Brain Research 113, no. 1-2 (March 1999): 67–73. http://dx.doi.org/10.1016/s0165-3806(98)00191-6.

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11

Wohl, Ellen, and Hema Achyuthan. "Substrate Influences on Incised‐Channel Morphology." Journal of Geology 110, no. 1 (January 2002): 115–20. http://dx.doi.org/10.1086/324207.

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12

Ralph, Stephen C., Geoffrey C. Poole, Loveday L. Conquest, and Robert J. Naiman. "Stream Channel Morphology and Woody Debris in Logged and Unlogged Basins of Western Washington." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 1 (January 1, 1994): 37–51. http://dx.doi.org/10.1139/f94-006.

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Channel morphology and habitat characteristics of stream segments draining unharvested old-growth forests were compared with those from streams within intensively and moderately logged basins. Sites covered a broad geographic range in western Washington State and were stratified by basin area and channel gradient. Although the number of pieces of large woody debris (LWD) within stream channels was unaffected by timber harvest, there was a clear reduction in LWD size in harvested basins. Timber harvest also resulted in a shift in location of LWD towards the channel margins, outside the low-flow wetted width of the channel. Intensive harvest simplified channel habitat by increasing riffle area and reducing pool area and depth, although the commonly used index of pool-to-riffle ratio appears inadequate to document these changes. Given the natural variation from stream to stream, we conclude that simple counts of instream LWD and channel units (habitat types) are not useful as management objectives. Instead, these attributes should be used collectively as indicators of the complexity and stability of in-stream habitat with respect to the specific channel and valley geomorphology.

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13

Liu, Zeng Wen, and Bo Huang. "Study on Burr Removal Technology of Micro-Channelsby a Micro Slurry Jet." Materials Science Forum 800-801 (July 2014): 815–19. http://dx.doi.org/10.4028/www.scientific.net/msf.800-801.815.

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Micro-channels are widely used in many fields. There are a lot of burrs in the process of micro-channel machining, which affect the performance of micro-channels. In this study, some polishing experiments are conducted for the burr removal of micro-channels by the micro slurry jet on the home made micro slurry jet machining system. The morphology and the roughness of the micro-channels are measured. The factors to influence the burr removal and the micro-channel surface quality are analyzed in order to take measures to improve the surface quality. The results show that the micro slurry jet polishing not only removes the micro channel burrs, but also improves the micro channel surface quality. It is helpful to increase the flow of medium inside micro channel.

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Qin, Yongpeng, Tiago M. Alves, José Antonio Constantine, Davide Gamboa, and Shiguo Wu. "Effect of channel tributaries on the evolution of submarine channel confluences (Espírito Santo Basin, SE Brazil)." GSA Bulletin 132, no. 1-2 (June 10, 2019): 263–72. http://dx.doi.org/10.1130/b35082.1.

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AbstractConfluences are geomorphologic features fed by distinct channel tributaries that record the contribution of multiple sediment sources. They are key features of both fluvial and submarine channels in geomorphologic and sedimentologic terms. Here, we use high-quality three-dimensional seismic data from SE Brazil to document the response of a submarine channel confluence to turbidity currents originating from a tributary. The studied channel system consists of a west tributary, an east tributary, and a postconfluence channel, with the last two comprising the main channel at present. Downstream from the confluence, changes in planform morphology and architecture were found due to the effect of turbidity currents sourced from the west tributary channel. A channel bend in the main channel curved toward the west when it was first formed but later curved toward the east, and so remains until the present day. This process led to the migration of the confluence point ∼500 m to the east, and changed the bed morphology from discordant (where the beds of tributaries and main channels meet at an unequal depth) to concordant (where the beds of tributaries and main channels meet at approximately the same depth). In addition to the channel bend near the confluence, two other bends further downstream recorded significant changes with time, increasing channel sinuosity from 1.11 to 1.72. These three channel bends near the confluence accumulated a large volume of sediment at their inner banks, generating depositional bars. Multiple channel forms within the depositional bars indicate the occurrence of large-scale lateral migration near the confluence. Hence, turbidity currents from the west tributary are shown to influence the submarine channel by promoting lateral channel migration, confluence migration, increases in channel sinuosity, and the formation of large depositional bars. These variations near the confluence reveal a change in tributary activity and a shift in sediment sources from east to west on the continental shelf. Such a shift suggests variations in sedimentary processes on the continental shelf probably due to avulsions on Doce River Delta.

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15

Montgomery, David R., and John M. Buffington. "Channel-reach morphology in mountain drainage basins." Geological Society of America Bulletin 109, no. 5 (May 1997): 596–611. http://dx.doi.org/10.1130/0016-7606(1997)109<0596:crmimd>2.3.co;2.

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McCarthy, R. A., and A. Sen Gupta. "Underwater channel estimation exploiting multipath feature morphology." Journal of the Acoustical Society of America 149, no. 2 (February 2021): 983–96. http://dx.doi.org/10.1121/10.0003494.

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17

Helm, Carina, Marwan A. Hassan, and David Reid. "Characterization of morphological units in a small, forested stream using close-range remotely piloted aircraft imagery." Earth Surface Dynamics 8, no. 4 (November 4, 2020): 913–29. http://dx.doi.org/10.5194/esurf-8-913-2020.

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Abstract. Forested, gravel-bed streams possess complex channel morphologies which are difficult to objectively characterize. The spatial scale necessary to adequately capture variability in these streams is often unclear, as channels are governed by irregularly spaced features and episodic processes. This issue is compounded by the high cost and time-consuming nature of field surveys in these complex fluvial environments. In larger streams, remotely piloted aircraft (RPA) have proven to be effective tools for characterizing channels at high resolutions over large spatial extents, but to date their use in small, forested streams with closed forest canopies has been limited. This paper seeks to demonstrate an effective method for classifying channel morphological units in small, forested streams and for providing information on the spatial scale necessary to capture the dominant spatial morphological variability of these channels. This goal was achieved using easily extractable data from close-range RPA imagery collected under the forest canopy (flying height of 5–15 m above ground level; ma.g.l.) in a small (width of 10–15 m) stream along its 3 km of salmon-bearing channel. First, the accuracy and coverage of RPA for extracting channel data were investigated through a subcanopy survey. From these survey data, relevant cross-sectional variables (hydraulic radius, sediment texture, and channel slope) were extracted from high-resolution point clouds and digital elevation models (DEMs) of the channel and used to characterize channel unit morphology using a principal component analysis-clustering (PCA-clustering) technique. Finally, the length scale required to capture dominant morphological variability was investigated from an analysis of morphological diversity along the channel. The results demonstrate that subcanopy RPA surveys provide a viable alternative to traditional ground-based survey approaches for mapping morphological units, with 87 % coverage of the main channel stream bed achieved. The PCA-clustering analysis provided a comparatively objective means of classifying channel unit morphology with a correct classification rate of 85 %. An analysis of the morphological diversity along the surveyed channel indicates that reaches of at least 15 bankfull width equivalents are required to capture the channel's dominant morphological heterogeneity. Altogether, the results provide a precedent for using RPA to characterize the morphology and diversity of forested streams under dense canopies.

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Vatne, G., and T. D. L. Irvine-Fynn. "Morphological dynamics of an englacial channel." Hydrology and Earth System Sciences Discussions 12, no. 8 (August 7, 2015): 7615–64. http://dx.doi.org/10.5194/hessd-12-7615-2015.

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Abstract. Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last four decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut and closure" streams, where englacial or subglacial flowpaths are created from the long-term incision of supraglacial channels. These flowpaths are reported to exhibit step-pool morphology, comprising knickpoints and/or knickzones, albeit exaggerated in dimensions in comparison to their supraglacial channel counterparts. However, little is known of the development of such channels' morphology. Here, we examine the spatial organization of step-pools and the upstream migration of steps, many of which form knickzones, with repeated surveys over a 10 year period in an englacial conduit in cold-based Austre Brøggerbreen, Svalbard. The observations show upstream knickpoint recession to be the dominant process for channel evolution. This is paralleled by an increase in average step height and conduit gradient over time. Characteristic channel reach types and step-riser forms are consistently observed in each of the morphological surveys reported. We suggest that the formation of steps has a hydrodynamic origin, where step-pool geometry is more efficient for energy dissipation than meanders, and that the englacial channel system is one in rapid transition rather than in dynamic equilibrium. The evolution and recession of knickzones reported here result in the formation of a 37 m moulin, suggesting over time the englacial channel may evolve towards a stable end-point characterised by a singular vertical descent to the local hydraulic base level. In light of this, our observations highlight the need to further examine the adjustment processes in cut-and-closure channels to better understand their coupling to supraglacial meltwater sources and role and potential significance in cold-based glacier hydrology and ice dynamics.

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Škarpich, Václav, Zdeněk Kašpárek, Tomáš Galia, and Jan Hradecký. "Anthropogenic impact and morphology channel response of Beskydian gravel-bed rivers: a case study of the Ostravice River, Czechia." Geografie 121, no. 1 (2016): 99–120. http://dx.doi.org/10.37040/geografie2016121010099.

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This paper presents an analysis of both the contemporary and historic development of the geomorphic regime of the Ostravice River channel in the Czech part of the Outer Western Carpathians. The assessment concentrates on the conditions and causes of the channel development in the last 200 years compared with the state of European channels. The original anabranching river pattern has gradually been replaced by a single narrowed channel. At some sections, the original riverbed has lowered by as much as 2.5 m in the second half of the 20th century. These changes were due to strong anthropogenic impacts in the form of river-channel control and construction of dams. A large influence on the contemporary processes was also exerted by changed hydrological conditions and a predisposition of flysch lithology in a channel bedrock to erosion. Currently, the deficit of transportable sedimentary material along with the changed morphology of channels with concentrated water flows are intensifying erosion processes.

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Teketel, Shewangizaw, Lars Lundegaard, Wegard Skistad, Unni Olsbye, Karl Petter Lillerud, Pablo Beato, and Stian Svelle. "Morphology Controlled Lifetime and Selectivity in Zeolite Catalysis." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C737. http://dx.doi.org/10.1107/s2053273314092626.

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Zeolites are widely used in the chemical industry for their catalytic properties and their ability to control the size and shape of both reactant and product molecules. In this presentation we will show unexpected catalytic properties of ZSM-57 and SUZ-4 during conversion of methanol to hydrocarbons (MTH). We have previously shown how analysis of anisotropic peak broadening in XRPD data [1] can reveal not only the average shape of the crystallites, but also how the zeolite channels are orientated relative to the morphology [2]. The same method was used to analyze the ZSM-57 and SUZ-4 samples revealing nano-sheet and -needle morphologies respectively. Electron imaging and diffraction furthermore revealed that the sheets of ZSM-57 are five-fold twinned with the 10-ring channel system perpendicular to the sheet. The 8-ring channel system would form a closed pentagon shape in defect free crystals. Based on these observations we will explain the remarkable MTH lifetime and selectivity displayed by the ZSM-57 and SUZ-4 samples respectively [3].

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21

Vatne, Geir, and Tristram D. L. Irvine-Fynn. "Morphological dynamics of an englacial channel." Hydrology and Earth System Sciences 20, no. 7 (July 21, 2016): 2947–64. http://dx.doi.org/10.5194/hess-20-2947-2016.

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Abstract. Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last 4 decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut-and-closure" streams, where englacial or subglacial flow paths are created from the long-term incision of supraglacial channels. These flow paths are reported to exhibit step-pool morphology, comprising knickpoints and/or knickzones, exaggerated in dimensions in comparison to supraglacial channels. However, little is known of the development of such channels' morphology. Here, we examine the spatial organisation of step pools and the upstream migration of steps, many of which form knickzones, with repeated surveys over a 10-year period in an englacial conduit in cold-based Austre Brøggerbreen, Svalbard. The observations show upstream step recession to be the dominant process for channel evolution. This is paralleled by an increase in average step height and conduit gradient over time. Characteristic channel-reach types and step-riser forms are consistently observed in each of the morphological surveys reported. We suggest that the formation of steps has a hydrodynamic origin, where step-pool geometry is more efficient for energy dissipation than meanders. The englacial channel system is one in rapid transition towards a quasi-equilibrium form within a decadal timescale. The evolution and recession of knickzones reported here result in the formation of a 37 m deep moulin shaft, suggesting that over time an incising supraglacial channel may evolve towards an englacial channel form exhibiting a stable end-point characterised by a singular vertical descent, which potentially can reach the glacier bed. This challenges the prevailing notions that crevasses or hydrofractures are needed to form deep moulins. Our observations highlight the need to further examine the adjustment processes in cut-and-closure channels to better understand their coupling to supraglacial meltwater sources and potential significance in cold-based glacier hydrology and ice dynamics.

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van Dijk, Wout M., Jana R. Cox, Jasper R. F. W. Leuven, Jelmer Cleveringa, Marcel Taal, Matthew R. Hiatt, Willem Sonke, Kevin Verbeek, Bettina Speckmann, and Maarten G. Kleinhans. "The vulnerability of tidal flats and multi-channel estuaries to dredging and disposal." Anthropocene Coasts 4, no. 1 (January 1, 2021): 36–60. http://dx.doi.org/10.1139/anc-2020-0006.

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Shipping fairways in estuaries are continuously dredged to maintain access for large vessels to major ports. However, several estuaries worldwide show adverse side effects to dredging activities, in particular affecting morphology and ecologically valuable habitats. We used physical scale experiments, field assessments of the Western Scheldt estuary (the Netherlands), and morphodynamic model runs to analyse the effects of dredging and future stresses (climate and sediment management) on a multi-channel system and its ecologically valuable intertidal flats. All methods indicate that dredging and disposal strategies are unfavourable to long-term morphology because dredging creates and propagates the imbalance between shallow and deeper parts of the estuary, causing a loss of valuable connecting channels and fixation of the tidal flats and main channel positions, while countering adverse effects by disposal strategy has limited effectiveness. Changing the disposal strategy towards main channel scour disposal can be economically and ecologically beneficial for the preservation of the multi-channel system. Further channel deepening will accelerate the adverse side effects, whereas future sea-level rise may revive the multi-channel system.

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Gong, Chenglin, Ronald J. Steel, Kun Qi, and Yingmin Wang. "Deep-water channel morphologies, architectures, and population densities in relation to stacking trajectories and climate states." GSA Bulletin 133, no. 1-2 (June 15, 2020): 287–306. http://dx.doi.org/10.1130/b35431.1.

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Abstract Deep-water channel morphologies, stratigraphy, and population densities in relation to stacking trajectories and climate states remain poorly constrained, and are highlighted by a sampling of 142 submarine channels. From the perspective of channel kinematics, turbidite channels exhibit tripartite lateral - random - vertical trajectories or unidirectional channel-complex trajectories, whereas contourite channels display oblique upslope trajectories. Turbidite channels tend to be deep and narrow and have two to three times more lateral migration than contourite channels, whereas contourite channels tend to be shallow and wide and have two to three times more vertical accretion. We relate such differences between channel morphology and stratigraphy to density contrast between flow and ambient fluid for contourite versus turbidite channels, which seems to have favored lateral channel migration in turbidite channels but channel thalweg deposition in contourite channels. Additionally, channels formed during a greenhouse climate state display low degrees of morphological and architectural variations, and are the minority in our global channel database (8% of total), although the Earth has been in a greenhouse state for 72% of the past 540 m.y. Icehouse channels, in contrast, exhibit high amplitudes of morphological and architectural variations and are the majority in the global channel family (92% of total), although the Earth has been in an icehouse state for 18% of the past 540 m.y. Such differences in channel-population densities between greenhouse and icehouse climates (8% versus 92%) suggest a weak global correlation of channel-population densities with warming greenhouse climates.

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Costigan, Katie H., and Joseph E. Gerken. "Channel morphology and flow structure of an abandoned channel under varying stages." Water Resources Research 52, no. 7 (July 2016): 5458–72. http://dx.doi.org/10.1002/2015wr017601.

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25

Chalov, R. S., and E. R. Chalova. "Geography of braided rivers within the territory of Russia." Известия Русского географического общества 151, no. 6 (December 20, 2019): 20–34. http://dx.doi.org/10.31857/s0869-6071151620-34.

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The paper represents the geographical analysis of braided river channels development and distribution for the first time in Russian Scientific Literature. On asmall-scale map of Russia we display the distribution of braided channels on small and middle mountain, semi-mountain and plain rivers, in free and limited conditions of channel changes development (on rivers with wide floodplain and incised channel), which are determined by geologic-geomorphologic structure of the territory. On the large and largest rivers we distinguish braided reaches of different morphological types according to the MSU classification (single, conjugated, one-sided and alternate one-sided, sub-parallel branches, etc) and also bifurcations as aconsequence of meander cut-off which complicate the morphology of straight and meandering channels. Separately we display bifurcations on the other structural levels of channel processes development point mid-channel bifurcations on mountain reaches of large rivers, split channels and deltaic braided reaches. The causes of different types of braided channels development in different natural conditions are described.

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Chalov, Roman S., Konstantin M. Berkovitch, Svetlana N. Ruleva, Aleksandr S. Zavadskiy, Pavel P. Golovlev, and Georgiy B. Golubcov. "FORMATION AND EVOLUTION OF PARALLEL-BRAIDED CHANNEL REACHES." Географический вестник = Geographical bulletin, no. 4(55) (2020): 110–25. http://dx.doi.org/10.17072/2079-7877-2020-4-110-125.

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The paper provides a comprehensive assessment of channel formation conditions and hydrological-morphological characteristics, and also considers the features of the channel changes regime of parallel-braided channel reaches, being the most complex and diverse in morphodynamics. The general condition for their development is a large width of channels (respectively, the maximum value of the criterion of the flow quasi-uniformity suggested by I.F. Karasev). In such channels, the flow is divided into two branches, between which, in the middle of the channel, occurs accumulation of sediments and formation of mid-channel bars and islands. At the same time, parallel-braided channels are the result of other channel types (non-meandering) development due to certain changes in determining factors: increased water content and sediment runoff, overgrowth of channel bars, as a result of which mid-channel bars turn into islands, and anthropogenic impacts on rivers. On sandy floodplain rivers, parallel-braided reaches are typical for low-stable and unstable channels in the absence of the directed influence from bedrock banks on the flow and when effective water discharge passes over the floodplain edge. The islands in such braided reaches are mostly small. On rivers with incised channels, they are either similar in morphology and the channel changes regime to wide floodplain unstable channels, differing from the latter in large islands with elongated shape, or form sculptural islands and are very stable. In any variety, parallel-braided channels are very individual in their channel changes regime and there are no universal channel control schemes for them.

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27

Nabegu, Aliyu Baba. "Impact of Urbanization on Channel Morphology: Some Comments." IOSR Journal of Environmental Science, Toxicology and Food Technology 8, no. 4 (2014): 40–45. http://dx.doi.org/10.9790/2402-08424045.

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28

Ichihara, Yasuko, Hirosato Kikuchi, Carlos Ibarra, Junji Sasaki, and Yasuhiro Maehara. "The Functions of Ca2+ Release Channel and Morphology." Anesthesiology 96, Sup 2 (September 2002): A102. http://dx.doi.org/10.1097/00000542-200209002-00102.

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29

Pradhan, Chandan, Vinay Chembolu, and Subashisa Dutta. "Impact of river interventions on alluvial channel morphology." ISH Journal of Hydraulic Engineering 25, no. 1 (March 26, 2018): 87–93. http://dx.doi.org/10.1080/09715010.2018.1453878.

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Moody, John A., and Brent M. Troutman. "Characterization of the spatial variability of channel morphology." Earth Surface Processes and Landforms 27, no. 12 (2002): 1251–66. http://dx.doi.org/10.1002/esp.403.

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Hilmes, Marsha M., and Ellen E. Wohl. "CHANGES IN CHANNEL MORPHOLOGY ASSOCIATED WITH PLACER MINING." Physical Geography 16, no. 3 (May 1995): 223–42. http://dx.doi.org/10.1080/02723646.1995.10642551.

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Dauwalter, Daniel C., Dale K. Splinter, William L. Fisher, and Richard A. Marston. "Geomorphology and stream habitat relationships with smallmouth bass (Micropterus dolomieu) abundance at multiple spatial scales in eastern Oklahoma." Canadian Journal of Fisheries and Aquatic Sciences 64, no. 8 (August 1, 2007): 1116–29. http://dx.doi.org/10.1139/f07-085.

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Fluvial geomorphic processes structure habitats important to stream fishes. We determined relationships between densities of smallmouth bass (Micropterus dolomieu) and ecoregions, watershed and reach morphology, and stream habitat in eastern Oklahoma, USA. Watershed and reach morphology were measured at 128 stream sites, and stream habitat and smallmouth bass abundance were measured in 1800 channel units. Variation in stream size, channel morphology, and substrate size constituted major physical differences among sites. Channel morphology differed among ecoregions in the largest streams. Densities of age-0 and age-1 and older smallmouth bass were approximately an order of magnitude greater in the Boston Mountains and Ozark Highlands streams than in Ouachita Mountains streams. Regression tree analysis explained less variation in age-0 (10-fold cross-validated relative error = 0.843) than in age-1 and older (relative error = 0.650) smallmouth bass densities and showed that stream size and channel-unit size were primary determinants of density. Channel morphology explained variation in densities in deep channel units of large streams, which was somewhat independent of ecoregion.

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Vetter, Philipp, Arnd Roth, and Michael Häusser. "Propagation of Action Potentials in Dendrites Depends on Dendritic Morphology." Journal of Neurophysiology 85, no. 2 (February 1, 2001): 926–37. http://dx.doi.org/10.1152/jn.2001.85.2.926.

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Action potential propagation links information processing in different regions of the dendritic tree. To examine the contribution of dendritic morphology to the efficacy of propagation, simulations were performed in detailed reconstructions of eight different neuronal types. With identical complements of voltage-gated channels, different dendritic morphologies exhibit distinct patterns of propagation. Remarkably, the range of backpropagation efficacies observed experimentally can be reproduced by the variations in dendritic morphology alone. Dendritic geometry also determines the extent to which modulation of channel densities can affect propagation. Thus in Purkinje cells and dopamine neurons, backpropagation is relatively insensitive to changes in channel densities, whereas in pyramidal cells, backpropagation can be modulated over a wide range. We also demonstrate that forward propagation of dendritically initiated action potentials is influenced by morphology in a similar manner. We show that these functional consequences of the differences in dendritic geometries can be explained quantitatively using simple anatomical measures of dendritic branching patterns, which are captured in a reduced model of dendritic geometry. These findings indicate that differences in dendritic geometry act in concert with differences in voltage-gated channel density and kinetics to generate the diversity in dendritic action potential propagation observed between neurons. They also suggest that changes in dendritic geometry during development and plasticity will critically affect propagation. By determining the spatial pattern of action potential signaling, dendritic morphology thus helps to define the size and interdependence of functional compartments in the neuron.

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Turowski, Jens M., and Rebecca Hodge. "A probabilistic framework for the cover effect in bedrock erosion." Earth Surface Dynamics 5, no. 2 (June 20, 2017): 311–30. http://dx.doi.org/10.5194/esurf-5-311-2017.

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Abstract. The cover effect in fluvial bedrock erosion is a major control on bedrock channel morphology and long-term channel dynamics. Here, we suggest a probabilistic framework for the description of the cover effect that can be applied to field, laboratory, and modelling data and thus allows the comparison of results from different sources. The framework describes the formation of sediment cover as a function of the probability of sediment being deposited on already alluviated areas of the bed. We define benchmark cases and suggest physical interpretations of deviations from these benchmarks. Furthermore, we develop a reach-scale model for sediment transfer in a bedrock channel and use it to clarify the relations between the sediment mass residing on the bed, the exposed bedrock fraction, and the transport stage. We derive system timescales and investigate cover response to cyclic perturbations. The model predicts that bedrock channels can achieve grade in steady state by adjusting bed cover. Thus, bedrock channels have at least two characteristic timescales of response. Over short timescales, the degree of bed cover is adjusted such that the supplied sediment load can just be transported, while over long timescales, channel morphology evolves such that the bedrock incision rate matches the tectonic uplift or base-level lowering rate.

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Tsay, David, and Rafael Yuste. "Role of Dendritic Spines in Action Potential Backpropagation: A Numerical Simulation Study." Journal of Neurophysiology 88, no. 5 (November 1, 2002): 2834–45. http://dx.doi.org/10.1152/jn.00781.2001.

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Two remarkable aspects of pyramidal neurons are their complex dendritic morphologies and the abundant presence of spines, small structures that are the sites of excitatory input. Although the channel properties of the dendritic shaft membrane have been experimentally probed, the influence of spine properties in dendritic signaling and action potential propagation remains unclear. To explore this we have performed multi-compartmental numerical simulations investigating the degree of consistency between experimental data on dendritic channel densities and backpropagation behavior, as well as the necessity and degree of influence of excitable spines. Our results indicate that measured densities of Na+ channels in dendritic shafts cannot support effective backpropagation observed in apical dendrites due to suprathreshold inactivation. We demonstrate as a potential solution that Na+ channels in spines at higher densities than those measured in the dendritic shaft can support extensive backpropagation. In addition, clustering of Na+ channels in spines appears to enhance their effect due to their unique morphology. Finally, we show that changes in spine morphology significantly influence backpropagation efficacy. These results suggest that, by clustering sodium channels, spines may serve to control backpropagation.

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Teo, Lay Lian, and B. S. Daya Sagar. "Modeling, description, and characterization of fractal pore via mathematical morphology." Discrete Dynamics in Nature and Society 2006 (2006): 1–24. http://dx.doi.org/10.1155/ddns/2006/89280.

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The aim of this paper is to provide description of fast, simple computational algorithms based upon mathematical morphology techniques to extract descriptions of pore channels—throats—and bodies and to represent them in 3D space, and to produce statistical characterization of their descriptions. Towards this goal, a model fractal binary pore is considered and is eroded recursively to generate different slices possessing decreasing degrees of porosity. By employing simple morphology-based approach, each slice of this pore space is decomposed into pore-channel, pore-throat, and pore-body, which are abstract structures that summarize the overall connectivity, orientation, and shape of the pore space. We consider the pore slices and their corresponding morphological quantities to stack them to further represent them in 3D space. We further provide a formulation essentially based on set theory to represent these three morphologic quantities to connect them appropriately across slices. The connected quantities are further fragmented to designate each fragmented portion with orders ranging from 1 toN.

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Beltaos, Spyros, Tom Carter, and Terry Prowse. "Morphology and genesis of deep scour holes in the Mackenzie Delta." Canadian Journal of Civil Engineering 38, no. 6 (June 2011): 638–49. http://dx.doi.org/10.1139/l11-034.

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A unique feature that has been detected in the course of past morphological studies of Mackenzie delta channels, and which is of particular concern to the design of pipeline crossings, is the frequent occurrence of very deep scour holes. A recent survey along East Channel revealed many additional holes, with maximum depths ranging from 13 to 37 m. Using the results of recent and past surveys, an inventory of known scour holes and associated morphological parameters is developed. Most holes occur near bends, and often next to recesses in the channel boundaries, known as scour bays. It is shown that presence of scour bays indicates deeper-than-expected holes while repeat surveys of three holes indicate stability. Previously postulated formative mechanisms of bay-associated holes are critically examined; scour under ice jams is eliminated while lake capture is considered likely. Practical implications of the present findings are discussed and research needs outlined.

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SUH, C. E., S. A. STANSFIELD, R. S. J. SPARKS, M. S. NJOME, M. N. WANTIM, and G. G. J. ERNST. "Morphology and structure of the 1999 lava flows at Mount Cameroon Volcano (West Africa) and their bearing on the emplacement dynamics of volume-limited flows." Geological Magazine 148, no. 1 (May 4, 2010): 22–34. http://dx.doi.org/10.1017/s0016756810000312.

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AbstractThe morphology and structure of the 1999 lava flows at Mount Cameroon volcano are documented and discussed in relation to local and source dynamics. Structures are analysed qualitatively and more detailed arguments are developed on the processes of levee formation and systematic links between flow dynamics and levee–channel interface geometry. The flows have clear channels bordered by four main types of levees: initial, accretionary, rubble and overflow levees. Thermally immature pahoehoe lava units with overflow drapes define the proximal zone, whereas rubble and accretionary levees are common in the distal region bordering thermally mature aa clinker or blocky aa flow channels. Pressure ridges, squeeze-ups and pahoehoe ropes are the prevalent compressive structures. Standlines displayed on clinkery breccias are interpreted to represent levee–channel interactions in response to changing flow levels. These data complement previous knowledge on lava flow morphology, thus far dominated by Etnean and Hawaiian examples.

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Ban, Yue, Benjamin E. Smith, and Michael R. Markham. "A highly polarized excitable cell separates sodium channels from sodium-activated potassium channels by more than a millimeter." Journal of Neurophysiology 114, no. 1 (July 2015): 520–30. http://dx.doi.org/10.1152/jn.00475.2014.

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The bioelectrical properties and resulting metabolic demands of electrogenic cells are determined by their morphology and the subcellular localization of ion channels. The electric organ cells (electrocytes) of the electric fish Eigenmannia virescens generate action potentials (APs) with Na+ currents >10 μA and repolarize the AP with Na+-activated K+ (KNa) channels. To better understand the role of morphology and ion channel localization in determining the metabolic cost of electrocyte APs, we used two-photon three-dimensional imaging to determine the fine cellular morphology and immunohistochemistry to localize the electrocytes' ion channels, ionotropic receptors, and Na+-K+-ATPases. We found that electrocytes are highly polarized cells ∼1.5 mm in anterior-posterior length and ∼0.6 mm in diameter, containing ∼30,000 nuclei along the cell periphery. The cell's innervated posterior region is deeply invaginated and vascularized with complex ultrastructural features, whereas the anterior region is relatively smooth. Cholinergic receptors and Na+ channels are restricted to the innervated posterior region, whereas inward rectifier K+ channels and the KNa channels that terminate the electrocyte AP are localized to the anterior region, separated by >1 mm from the only sources of Na+ influx. In other systems, submicrometer spatial coupling of Na+ and KNa channels is necessary for KNa channel activation. However, our computational simulations showed that KNa channels at a great distance from Na+ influx can still terminate the AP, suggesting that KNa channels can be activated by distant sources of Na+ influx and overturning a long-standing assumption that AP-generating ion channels are restricted to the electrocyte's posterior face.

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Shen, De Jiu, Wei Chao Gu, Yu Lin Wang, Guang Zhong Xing, and Philip Nash. "Surface Morphology and Discharge Channel Temperature Estimation of PEO Ceramic Coatings on Aluminum." Materials Science Forum 546-549 (May 2007): 1135–40. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.1135.

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The surface roughness and morphology of the ceramic coatings fabricated on industrially pure aluminum by the plasma electrolytic oxidation (PEO) technique with a hetero-polar pulsed current ceramic synthesizing system were investigated. A model for the process was established. Based on this a formula was deduced to estimate the temperature rise rate at the corresponding locations before the plasma discharge channels have formed during the PEO process, and the channels’ temperature when the plasma discharges occur. Results show that the PEO ceramic coatings grow by an alternating coating melting and solidifying way; The coating roughness becomes greater and the plasma discharge channel population in the ceramic coatings decreases while the pores enlarge with PEO treatment time and current. With the deduced formula, the PEO alumina coating on industrially pure aluminum was taken as an example for validation of the model.

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Leuven, Jasper R. F. W., Sanja Selaković, and Maarten G. Kleinhans. "Morphology of bar-built estuaries: empirical relation between planform shape and depth distribution." Earth Surface Dynamics 6, no. 3 (September 11, 2018): 763–78. http://dx.doi.org/10.5194/esurf-6-763-2018.

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Abstract. Fluvial–tidal transitions in estuaries are used as major shipping fairways and are characterised by complex bar and channel patterns with a large biodiversity. Habitat suitability assessment and the study of interactions between morphology and ecology therefore require bathymetric data. While imagery offers data of planform estuary dimensions, only for a few natural estuaries are bathymetries available. Here we study the empirical relation between along-channel planform geometry, obtained as the outline from imagery, and hypsometry, which characterises the distribution of along-channel and cross-channel bed levels. We fitted the original function of Strahler (1952) to bathymetric data along four natural estuaries. Comparison to planform estuary shape shows that hypsometry is concave at narrow sections with large channels, while complex bar morphology results in more convex hypsometry. We found an empirical relation between the hypsometric function shape and the degree to which the estuary width deviates from an ideal convergent estuary, which is calculated from river width and mouth width. This implies that the occurring bed-level distributions depend on inherited Holocene topography and lithology. Our new empirical function predicts hypsometry and along-channel variation in intertidal and subtidal width. A combination with the tidal amplitude allows for an estimate of inundation duration. The validation of the results on available bathymetry shows that predictions of intertidal and subtidal area are accurate within a factor of 2 for estuaries of different size and character. Locations with major human influence deviate from the general trends because dredging, dumping, land reclamation and other engineering measures cause local deviations from the expected bed-level distributions. The bathymetry predictor can be used to characterise and predict estuarine subtidal and intertidal morphology in data-poor environments.

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Falcini, F., and E. Salusti. "Friction and mixing effects on potential vorticity for bottom current crossing a marine strait: an application to the Sicily Channel (central Mediterranean Sea)." Ocean Science 11, no. 3 (May 21, 2015): 391–403. http://dx.doi.org/10.5194/os-11-391-2015.

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Abstract. We discuss here the evolution of vorticity and potential vorticity (PV) for a bottom current crossing a marine channel in shallow-water approximation, focusing on the effect of friction and mixing. The purpose of this research is indeed to investigate the role of friction and vertical entrainment on vorticity and PV spatial evolution in channels or straits when along-channel morphology variations are significant. To pursue this investigation, we pose the vorticity and PV equations for a homogeneous bottom water vein and we calculate these two quantities as an integral form. Our theoretical findings are considered in the context of in situ hydrographic data related to the Eastern Mediterranean Deep Water (EMDW), i.e., a dense, bottom water vein that flows northwestward, along the Sicily Channel (Mediterranean Sea). Indeed, the narrow sill of this channel implies that friction and entrainment need to be considered. Small tidal effects in the Sicily Channel allow for a steady theoretical approach. We argue that bottom current vorticity is prone to significant sign changes and oscillations due to topographic effects when, in particular, the current flows over the sill of a channel. These vorticity variations are, however, modulated by frictional effects due to seafloor roughness and morphology. Such behavior is also reflected in the PV spatial evolution, which shows an abrupt peak around the sill region. Our diagnoses on vorticity and PV allow us to obtain general insights about the effect of mixing and friction on the pathway and internal structure of bottom-trapped currents flowing through channels and straits, and to discuss spatial variability of the frictional coefficient. Our approach significantly differs from other PV-constant approaches previously used in studying the dynamics of bottom currents flowing through rotating channels.

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Borák, Libor. "The role of foliar litter-fall in forming channel morphology step-pool of high-gradient streams in Moravskoslezské Beskydy Mts." Geografie 122, no. 1 (2017): 83–99. http://dx.doi.org/10.37040/geografie2017122010083.

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Channel morphology step-pool represents a morphodynamic complex influenced by large woody debris and litter-fall. The aim of this paper is to determine the impact of litter-fall on the channel morphology step-pool. General conclusions regarding the influence of litter-fall on channel morphology step-pool were based on results of geomorphological analyses. The study showed differences between river segments with or without foliaged steps. The pools following foliaged steps have a finer grain size composition of sediment. They are also larger, shallower and have a higher retention capacity. Foliaged steps help to decrease potential energy of water more effectively. If the litter-fall is permanently preserved at the step, it makes it more resistant to extreme water flows. As a result, it enables the development of a fully functional channel morphology step-pool.

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KAMINTZIS, J. E., J. P. P. JONES, T. D. L. IRVINE-FYNN, T. O. HOLT, P. BUNTING, S. J. A. JENNINGS, P. R. PORTER, and B. HUBBARD. "Assessing the applicability of terrestrial laser scanning for mapping englacial conduits." Journal of Glaciology 64, no. 243 (December 20, 2017): 37–48. http://dx.doi.org/10.1017/jog.2017.81.

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ABSTRACTThe morphology of englacial drainage networks and their temporal evolution are poorly characterised, particularly within cold ice masses. At present, direct observations of englacial channels are restricted in both spatial and temporal resolution. Through novel use of a terrestrial laser scanning (TLS) system, the interior geometry of an englacial channel in Austre Brøggerbreen, Svalbard, was reconstructed and mapped. Twenty-eight laser scan surveys were conducted in March 2016, capturing the glacier surface around a moulin entrance and the uppermost 122 m reach of the adjoining conduit. The resulting point clouds provide detailed 3-D visualisation of the channel with point accuracy of 6.54 mm, despite low (<60%) overall laser returns as a result of the physical and optical properties of the clean ice, snow, hoar frost and sediment surfaces forming the conduit interior. These point clouds are used to map the conduit morphology, enabling extraction of millimetre-to-centimetre scale geometric measurements. The conduit meanders at a depth of 48 m, with a sinuosity of 2.7, exhibiting teardrop shaped cross-section morphology. This improvement upon traditional surveying techniques demonstrates the potential of TLS as an investigative tool to elucidate the nature of glacier hydrological networks, through reconstruction of channel geometry and wall composition.

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Pagin, A. O., N. B. Baryshnikov, E. V. Pol'tsina, and T. S. Selina. "CHANNEL AND FLOOD-PLAIN MORPHOLOGY AND ITS IMPACT ON CHANNEL AND FLOOD-PLAIN STREAMS." Geomorphology RAS, no. 3 (June 20, 2015): 67. http://dx.doi.org/10.15356/0435-4281-2010-3-67-72.

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Fashae, Olutoyin, and Adeyemi Oludapo Olusola. "Landuse Types within Channel Corridor and River Channel Morphology of River Ona, Ibadan, Nigeria." Indonesian Journal of Geography 49, no. 2 (December 27, 2017): 111. http://dx.doi.org/10.22146/ijg.12738.

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The importance of river a corridor warrants a well thought out and balanced management approach because it helps in improving or maintaining water quality, protecting wetlands, etc. Hence, this study seeks to identify major landuse types within the River Ona Corridor; examine the impact of these landuse types within the River Ona corridor on its channel morphology and understand the risk being posed by these landuse types. The study is designed by selecting two reaches of six times the average width from each of the four major landuse types that exist along the river corridor. This study revealed that along the downstream section of Eleyele Dam of River Ona, natural forest stabilizes river channel banks, thereby presenting a narrow and shallow width and depth respectively but the widest of all is found at the agricultural zones.

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Zimmermann, André, and Michael Church. "Channel morphology, gradient profiles and bed stresses during flood in a step–pool channel." Geomorphology 40, no. 3-4 (October 2001): 311–27. http://dx.doi.org/10.1016/s0169-555x(01)00057-5.

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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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Adams, Christopher M., Michael G. Anderson, David G. Motto, Margaret P. Price, Wayne A. Johnson, and Michael J. Welsh. "Ripped Pocket and Pickpocket, Novel Drosophila DEG/ENaC Subunits Expressed in Early Development and in Mechanosensory Neurons." Journal of Cell Biology 140, no. 1 (January 12, 1998): 143–52. http://dx.doi.org/10.1083/jcb.140.1.143.

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Drosophila melanogaster has proven to be a good model for understanding the physiology of ion channels. We identified two novel Drosophila DEG/ ENaC proteins, Pickpocket (PPK) and Ripped Pocket (RPK). Both appear to be ion channel subunits. Expression of RPK generated multimeric Na+ channels that were dominantly activated by a mutation associated with neurodegeneration. Amiloride and gadolinium, which block mechanosensation in vivo, inhibited RPK channels. Although PPK did not form channels on its own, it associated with and reduced the current generated by a related human brain Na+ channel. RPK transcripts were abundant in early stage embryos, suggesting a role in development. In contrast, PPK was found in sensory dendrites of a subset of peripheral neurons in late stage embryos and early larvae. In insects, such multiple dendritic neurons play key roles in touch sensation and proprioception and their morphology resembles human mechanosensory free nerve endings. These results suggest that PPK may be a channel subunit involved in mechanosensation.

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Sandercock, P. J., J. M. Hooke, and J. M. Mant. "Vegetation in dryland river channels and its interaction with fluvial processes." Progress in Physical Geography: Earth and Environment 31, no. 2 (April 2007): 107–29. http://dx.doi.org/10.1177/0309133307076106.

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Vegetation forms a major component of the channel environment of dryland rivers in Mediterranean Europe yet the interactions between vegetation and fluvial processes in dryland river channels have received relatively little attention. Characteristic of dryland channels is a degree of complexity and irregularity in morphology coupled with abrupt changes in patterns of riparian vegetation along their course. This is in contrast to more temperate and humid channels, which show strong downstream trends in morphology and a regularity in the distribution of vegetation across the valley floor. The general effect of vegetation in these channels appears to be to enhance the processes of sedimentation and increase resistance to erosion. However, at high stress levels vegetation may be removed. The limited work that has been undertaken indicates that there is considerable variability in the effect that vegetation has on channel processes, depending on both the magnitude of the flow and characteristics of the vegetation, such as their distribution and positioning within the channel and factors such as plant flexibility, cross-sectional area (blockage ratio), number of stems. Studies of sediment connectivity are beginning to yield new insights into the dynamics of dryland rivers, and in particular the role of vegetation in reducing the connectivity of sediment transfers downstream. Detailed surveying at monitored sites such as is being carried out within the EU-funded project RECONDES is required to study the interactions between vegetation, sediment and flow in dryland rivers of the Mediterranean region.

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Journal articles on the topic 'Channel morphology'

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