Controls on cutoff formation along a tropical meandering river in the Amazon Basin

NASA Astrophysics Data System (ADS)

Ahmed, J.; Constantine, J. A.

2016-12-01

The termination of meander bends is an inherent part of the evolution of meandering rivers. Cutoffs are produced by one of two mechanisms: neck cutoffs occur when two adjacent meanders converge, while chute cutoffs are generated by flood-driven floodplain incision, resulting in a shorter, steeper channel path. Here we use an annually-resolved record of Landsat imagery, coupled with daily discharge data to assess the role of high-magnitude discharges (Q ≥ QBF) on cutoff formation along the Rio Beni, Bolivia. Our results suggest that despite numerous above-bankfull events, the dominant cutoff mechanism operating on the Beni is neck cutoff. Evaluating the formation of these cutoffs reveals that migration rates accelerate during years of high discharge, and eventually cause the migrating bends to breach. The density of floodplain vegetation and the medium into which the channel migrated was also responsible for the patterns of cutoff documented along this river. The presence of existing floodplain channels permitted the river to divert its flow along shorter courses thereby facilitating cutoff, and limiting sinuosity growth. Understanding the long-term evolution of meandering channels is important since their morphodynamics are responsible for the creation of highly biodiverse riparian habitats, as well as the store and release of alluvial material. Moreover, the interactions between discharge and the channel-floodplain system are integral for the functioning and long-term evolution of these landscapes, particularly in the face of global climate change.

A 184-year record of river meander migration from tree rings, aerial imagery, and cross sections

NASA Astrophysics Data System (ADS)

Schook, Derek M.; Rathburn, Sara L.; Friedman, Jonathan M.; Wolf, J. Marshall

2017-09-01

Channel migration is the primary mechanism of floodplain turnover in meandering rivers and is essential to the persistence of riparian ecosystems. Channel migration is driven by river flows, but short-term records cannot disentangle the effects of land use, flow diversion, past floods, and climate change. We used three data sets to quantify nearly two centuries of channel migration on the Powder River in Montana. The most precise data set came from channel cross sections measured an average of 21 times from 1975 to 2014. We then extended spatial and temporal scales of analysis using aerial photographs (1939-2013) and by aging plains cottonwoods along transects (1830-2014). Migration rates calculated from overlapping periods across data sets mostly revealed cross-method consistency. Data set integration revealed that migration rates have declined since peaking at 5 m/year in the two decades after the extreme 1923 flood (3000 m3/s). Averaged over the duration of each data set, cross section channel migration occurred at 0.81 m/year, compared to 1.52 m/year for the medium-length air photo record and 1.62 m/year for the lengthy cottonwood record. Powder River peak annual flows decreased by 48% (201 vs. 104 m3/s) after the largest flood of the post-1930 gaged record (930 m3/s in 1978). Declining peak discharges led to a 53% reduction in channel width and a 29% increase in sinuosity over the 1939-2013 air photo record. Changes in planform geometry and reductions in channel migration make calculations of floodplain turnover rates dependent on the period of analysis. We found that the intensively studied last four decades do not represent the past two centuries.

A 184-year record of river meander migration from tree rings, aerial imagery, and cross sections

USGS Publications Warehouse

Schook, Derek M.; Rathburn, Sara L.; Friedman, Jonathan M.; Wolf, J. Marshall

2017-01-01

Channel migration is the primary mechanism of floodplain turnover in meandering rivers and is essential to the persistence of riparian ecosystems. Channel migration is driven by river flows, but short-term records cannot disentangle the effects of land use, flow diversion, past floods, and climate change. We used three data sets to quantify nearly two centuries of channel migration on the Powder River in Montana. The most precise data set came from channel cross sections measured an average of 21 times from 1975 to 2014. We then extended spatial and temporal scales of analysis using aerial photographs (1939–2013) and by aging plains cottonwoods along transects (1830–2014). Migration rates calculated from overlapping periods across data sets mostly revealed cross-method consistency. Data set integration revealed that migration rates have declined since peaking at 5 m/year in the two decades after the extreme 1923 flood (3000 m3/s). Averaged over the duration of each data set, cross section channel migration occurred at 0.81 m/year, compared to 1.52 m/year for the medium-length air photo record and 1.62 m/year for the lengthy cottonwood record. Powder River peak annual flows decreased by 48% (201 vs. 104 m3/s) after the largest flood of the post-1930 gaged record (930 m3/s in 1978). Declining peak discharges led to a 53% reduction in channel width and a 29% increase in sinuosity over the 1939–2013 air photo record. Changes in planform geometry and reductions in channel migration make calculations of floodplain turnover rates dependent on the period of analysis. We found that the intensively studied last four decades do not represent the past two centuries

Modeling the Long-term Planform Evolution of Meandering Rivers in Confined Alluvial Valleys: Etsch-Adige River, NE Italy.

NASA Astrophysics Data System (ADS)

Zen, S.; Bogoni, M.; Zolezzi, G.; Lanzoni, S.; Scorpio, V.

2016-12-01

We combine the use of a morphodynamic model for river meander planform evolution with a geological dataset to investigate the influence of external confinements on the long-term evolution of a meandering river flowing in an Alpine valley. The analysis focuses on a 100 km reach of the Adige River, NE Italy, which had several sinuous/meandering sections before being extensively channelized in the 1800s. Geological surveys and historical maps revealed that many sections of the study reach impinge on the borders of the valley during its evolution. Moreover, a marked spatial heterogeneity in floodplain vertical accretion rates likely reflects preferential positions of the river channel in the floodplain. Valley confinements are represented by bedrock outcrops and by alluvial fans created by lateral tributaries, and were extracted from the geological and historical maps to build the computational domain for the meander morphodynamic model. The model predicts the long-term planform evolution of a meandering river based on a linear solution of the 2D De St Venant-Exner differential system and can manage changes in floodplain erodibility. Model applications allow to isolate the effects of valley bedrock and of alluvial fans in constraining the lateral channel migration. Modeled river channel persistence maps are compared with the available geological information. The present work allows further insights into the role of external confinements to river meander belts, which have been conducted so far mostly assuming the channel to evolve in unconfined floodplains. Future research shall incorporate model components for floodplain vertical accretion rates and for the advancement of alluvial fans occurring at the same time scale considered for meander evolution.

Application of meandering centreline migration modelling and object-based approach of Long Nab member

NASA Astrophysics Data System (ADS)

Saadi, Saad

2017-04-01

Characterizing the complexity and heterogeneity of the geometries and deposits in meandering river system is an important concern for the reservoir modelling of fluvial environments. Re-examination of the Long Nab member in the Scalby formation of the Ravenscar Group (Yorkshire, UK), integrating digital outcrop data and forward modelling approaches, will lead to a geologically realistic numerical model of the meandering river geometry. The methodology is based on extracting geostatistics from modern analogous, meandering rivers that exemplify both the confined and non-confined meandering point bars deposits and morphodynamics of Long Nab member. The parameters derived from the modern systems (i.e. channel width, amplitude, radius of curvature, sinuosity, wavelength, channel length and migration rate) are used as a statistical control for the forward simulation and resulting object oriented channel models. The statistical data derived from the modern analogues is multi-dimensional in nature, making analysis difficult. We apply data mining techniques such as parallel coordinates to investigate and identify the important relationships within the modern analogue data, which can then be used drive the development of, and as input to the forward model. This work will increase our understanding of meandering river morphodynamics, planform architecture and stratigraphic signature of various fluvial deposits and features. We will then use these forward modelling based channel objects to build reservoir models, and compare the behaviour of the forward modelled channels with traditional object modelling in hydrocarbon flow simulations.

River meanders - Theory of minimum variance

USGS Publications Warehouse

Langbein, Walter Basil; Leopold, Luna Bergere

1966-01-01

Meanders are the result of erosion-deposition processes tending toward the most stable form in which the variability of certain essential properties is minimized. This minimization involves the adjustment of the planimetric geometry and the hydraulic factors of depth, velocity, and local slope.The planimetric geometry of a meander is that of a random walk whose most frequent form minimizes the sum of the squares of the changes in direction in each successive unit length. The direction angles are then sine functions of channel distance. This yields a meander shape typically present in meandering rivers and has the characteristic that the ratio of meander length to average radius of curvature in the bend is 4.7.Depth, velocity, and slope are shown by field observations to be adjusted so as to decrease the variance of shear and the friction factor in a meander curve over that in an otherwise comparable straight reach of the same riverSince theory and observation indicate meanders achieve the minimum variance postulated, it follows that for channels in which alternating pools and riffles occur, meandering is the most probable form of channel geometry and thus is more stable geometry than a straight or nonmeandering alinement.

On the Fundamental Cause of River Meanders

NASA Astrophysics Data System (ADS)

Sahagian, D. L.; Diplas, P.

2017-12-01

River meandering has been attributed to the erosion and deposition of sediments along river banks, yet the fundamental cause of the instability has not been heretofore identified. In this conceptual study, we address the conditions that lead to the meander instability, in effect "upstream" of the many previous and thorough analyses of hydraulics and the alternating erosional/depositional pattern that ensues once such conditions exist. Rivers are only one of many fluid systems that exhibit meandering behavior, and no other involves sediments at all. Other examples include the gulf stream, glacial meltwater, the jet stream, channels in submarine fans, water falling directly down from a faucet, derailed trains and even tractor trailer trucks. As such, a universal criterion is needed to explain meandering in general. We show that meandering in all systems is driven by the existence of an adverse pressure gradient, such that the resulting deceleration imposed upon the fluid causes it to be energetically favorable to divert the flow to either side of its original direction. This universal framework makes it possible to determine under what conditions the meandering instability will be manifest in altered flow/channel morphology.

Modeling meander morphodynamics over self-formed heterogeneous floodplains

NASA Astrophysics Data System (ADS)

Bogoni, Manuel; Putti, Mario; Lanzoni, Stefano

2017-06-01

This work addresses the signatures embedded in the planform geometry of meandering rivers consequent to the formation of floodplain heterogeneities as the river bends migrate. Two geomorphic features are specifically considered: scroll bars produced by lateral accretion of point bars at convex banks and oxbow lake fills consequent to neck cutoffs. The sedimentary architecture of these geomorphic units depends on the type and amount of sediment, and controls bank erodibility as the river impinges on them, favoring or contrasting the river migration. The geometry of numerically generated planforms obtained for different scenarios of floodplain heterogeneity is compared to that of natural meandering paths. Half meander metrics and spatial distribution of channel curvatures are used to disclose the complexity embedded in meandering geometry. Fourier Analysis, Principal Component Analysis, Singular Spectrum Analysis and Multivariate Singular Spectrum Analysis are used to emphasize the subtle but crucial differences which may emerge between apparently similar configurations. A closer similarity between observed and simulated planforms is attained when fully coupling flow and sediment dynamics (fully-coupled models) and when considering self-formed heterogeneities that are less erodible than the surrounding floodplain.

Paleohydrological methods and some examples from Swedish fluvial environments. II - River meanders.

USGS Publications Warehouse

Williams, G.P.

1984-01-01

Empirical relations are developed between river-meander features and water-discharge characteristics for 19 reaches along Swedish rivers. In these relations, either average channel width or average radius of curvature of meander arcs can be used to estimate average annual peak discharge and average daily discharge. By accepting certain assumptions, the relations can be applied to other meandering Swedish rivers, present or ancient. The Oster-Dalalven River near Mora is used as an example.-Author

Mountain river meanders and typhoon strike frequency in the western Pacific

NASA Astrophysics Data System (ADS)

Stark, C. P.; Barbour, J.; Hsieh, M.; Hovius, N.; Jen, C.; Chen, M.

2004-12-01

Bedrock-floored mountain rivers are shaped by erosion processes that ultimately control the evolution of the landscape on geological time scales. In mountains across the western Pacific, meanders in bedrock channels are common and often emerge during incision rather than inherit their sinuosity from a past alluvial form. Incising emergent meanders are important because they reveal a process of lateral channel erosion at least as fast as the vertical rate erosion. Here we report a remarkable link between incised meander development and typhoon strike frequency, a good proxy for extreme rainfall and flood discharge. Using satellite imagery, shuttle-radar topographic data and a 58~year inventory of typhoon tracks, we mapped meander abundance and quantified regional densities of mountain river sinuosity and typhoon strikes. Our analysis shows that eroding meanders are most common in the typhoon-prone islands of Japan, Taiwan and the Philippines, and in rivers incising weak lithologies. One might expect that the faster the erosion rate, the greater the meandering, but we have found that monthly mean rainfall - and therefore mean discharge - correlates very poorly with sinuosity. Instead, the variability of rainfall, and presumably discharge, about the mean explains bedrock meander development much better. Mountain river sinuosity, for geologically similar bedrock, increases in a roughly linear fashion with typhoon strike frequency. The coefficient of variation of monthly rainfall (standard deviation normalized by the mean) exhibits a similar trend. We deduce that extreme flood discharge, e.g. driven by typhoon rainfall, accelerates lateral erosion rates and spurs meander development in mountain rivers.

Meandering down to the Sea: The Wandering Ways of Rivers.

ERIC Educational Resources Information Center

Aslamazov, Lev

1992-01-01

Discusses the hydrodynamic reasons why a riverbed meanders through a plain. Describes how water movement at a bend in a river causes erosion and changes in the riverbed. Provides a mathematical model to explain the periodic shape of meanders of a river in a plain. (MDH)

Integration of fluvial erosion factors for predicting landslides along meandering rivers

NASA Astrophysics Data System (ADS)

Chen, Yi-chin; Chang, Kang-tsung; Ho, Jui-yi

2015-04-01

River incision and lateral erosion are important geomorphologic processes in mountainous areas of Taiwan. During a typhoon or storm event, the increase of water discharge, flow velocity, and sediment discharge enhances the power of river erosion on channel bank. After the materials on toe of hillslope were removed by river erosion, landslides were triggered at outer meander bends. Although it has been long expected that river erosion can trigger landslide, studies quantifying the effects of river erosion on landslide and the application of river erosion index in landslide prediction are still overlooked. In this study, we investigated the effect of river erosion on landslide in a particular meanders landscape of the Jhoukou River, southern Taiwan. We developed a semi-automatic model to separate meandering lines into several reach segments based on the inflection points and to calculate river erosion indexes, e.g. sinuosity of meander, stream power, and stream order, for each reach segment. This model, then, built the spatial relationship between the reaches and its corresponding hillslopes, of which the toe was eroded by the reach. Based on the spatial relationship, we quantified the correlations between these indexes and landslides triggered by Typhoon Morakot in 2009 to examine the effects of river erosion on landslide. The correlated indexes were then used as landslide predictors in logistic regression model. Results of the study showed that there is no significant correlation between landslide density and meander sinuosity. This may be a result of wider channel dispersing the erosion at a meandering reach. On the other hand, landslide density at concave bank is significantly higher than that at convex bank in the downstream (stream order > 3), but that is almost the same in the upstream (stream order < 3). This may imply that river sediment play different roles between down- and upstream segments. River sediment in the upstream is an erosion agent vertically

Lateral migration of the Middle Sacramento River, California

USGS Publications Warehouse

Brice, James Coble

1977-01-01

Rates and processes of lateral erosion were studied for the middle Sacramento River between Chico Landing and Colusa, Calif. , a river distance of about 50 miles which is bordered by valuable agricultural land. The study is based on comparison of maps made during 1867-1949 and on aerial photographs made during 1924-74. Meander loops migrate by downstream translation in a direction nearly perpendicular to the loop axis. Loops are cut off by straight or diagonal chutes across the meander neck. The sinuosity of the river has gradually decreased from a value of 1.56 in 1896 to 1.35 in 1974. The morphology and curvature of meander loops cut off before white settlers came to the area indicate that the river was more stable, as well as more sinuous , then than now; subsequent morphologic changes are attributed mainly to the clearing of riparian vegetation and the effects of levees in reducing the area of overflow. The bank-erosion is 1.82 acres per year per stream mile or about 15 feet per year per stream foot for the period 1896-1974. (Woodard-USGS)

How Do River Meanders Change with Sea Level Rise and Fall?

NASA Astrophysics Data System (ADS)

Scamardo, J. E.; Kim, W.

2016-12-01

River meander patterns are controlled by numerous factors, including variations in water discharge, sediment input, and base level. However, the effect of sea level rise and fall on meandering rivers has not been thoroughly quantified. This study examines geomorphic changes to meandering rivers as a result of sea level rise and fall. Twenty experimental runs using coarse-grained walnut shell sediment (D50= 500 microns) in a flume tank (2.4m x 0.6m x 0.1m) tested the optimal initial conditions for creating meandering rivers in a laboratory setting as well as variations in base level rise and fall rates. Geomorphic changes were recorded by camera images every 20 seconds for a duration of 4 hours per experiment. Seventeen experiments tested the effects of changes in initial base levels, water discharge between 200 and 400 mL/min, and sediment to water input ratios between 1:1000 and 1:250 while measuring sinuosity, channel geometry, and the timescale of the channel to reach a stable form. Sinuosity and channel activity increased with increasing water discharge, initial base level, and the sediment to water ratio to a point after which the activity decreased with increasing sediment input. Base-level change experiments used initial conditions of 400 mL/min, a 1:750 sediment to water input ratio, and a 6 cm initial base-level to induce river meanders for the initial 2 hours before base-level change occurred. Three separate experiments investigated the effects of increasing rates of sea level change: 0.07 cm/min, 0.1 cm/min, and 0.2 cm/min. Experimental sea level was decreased constantly from a high-stand of 6 cm to a low-stand of 2 cm back to the high-stand base-level in each experiment. The rates of change in the experiments scale roughly from central to glacial cycles. In all three experiments, sea level fall induced meander cut-off while sea level rise prompted greater rates of meander bend erosion and meander growth. Sinuosity increased by 12%, 13.5%, and 24

Methodology for calculating shear stress in a meandering channel

Treesearch

Kyung-Seop Sin

2010-01-01

Shear stress in meandering channels is the key parameter to predict bank erosion and bend migration. A representative study reach of the Rio Grande River in central New Mexico has been modeled in the Hydraulics Laboratory at CSU. To determine the shear stress distribution in a meandering channel, the large scale (1:12) physical modeling study was conducted in the...

Numerical Estimation of the Outer Bank Resistance Characteristics in AN Evolving Meandering River

NASA Astrophysics Data System (ADS)

Wang, D.; Konsoer, K. M.; Rhoads, B. L.; Garcia, M. H.; Best, J.

2017-12-01

Few studies have examined the three-dimensional flow structure and its interaction with bed morphology within elongate loops of large meandering rivers. The present study uses a numerical model to simulate the flow pattern and sediment transport, especially the flow close to the outer-bank, at two elongate meandering loops in Wabash River, USA. The numerical grid for the model is based on a combination of airborne LIDAR data on floodplains and the multibeam data within the river channel. A Finite Element Method (FEM) is used to solve the non-hydrostatic RANS equation using a K-epsilon turbulence closure scheme. High-resolution topographic data allows detailed numerical simulation of flow patterns along the outer bank and model calibration involves comparing simulated velocities to ADCP measurements at 41 cross sections near this bank. Results indicate that flow along the outer bank is strongly influenced by large resistance elements, including woody debris, large erosional scallops within the bank face, and outcropping bedrock. In general, patterns of bank migration conform with zones of high near-bank velocity and shear stress. Using the existing model, different virtual events can be simulated to explore the impacts of different resistance characteristics on patterns of flow, sediment transport, and bank erosion.

Stereo Anaglyphs of River Meanders in Eberswalde Delta

NASA Image and Video Library

2007-01-10

This anaglyph from NASA Mars Reconnaissance Orbiter spacecraft, shows that Eberswalde Delta contains river meanders, which indicate that flowing water was present for an extended period of time. 3D glasses are necessary to view this image.

River channel patterns: Braided, meandering, and straight

USGS Publications Warehouse

Leopold, Luna Bergere; Wolman, M. Gordon

1957-01-01

Channel pattern is used to describe the plan view of a reach of river as seen from an airplane, and includes meandering, braiding, or relatively straight channels.Natural channels characteristically exhibit alternating pools or deep reaches and riffles or shallow reaches, regardless of the type of pattern. The length of the pool or distance between riffles in a straight channel equals the straight line distance between successive points of inflection in the wave pattern of a meandering river of the same width. The points of inflection are also shallow points and correspond to riffles in the straight channel. This distance, which is half the wavelength of the meander, varies approximately as a linear function of channel width. In the data we analysed the meander wavelength, or twice the distance between successive riffles, is from 7 to 12 times the channel width. It is concluded that the mechanics which may lead to meandering operate in straight channels.River braiding is characterized by channel division around alluvial islands. The growth of an island begins as the deposition of a central bar which results from sorting and deposition of the coarser fractions of the load which locally cannot be transported. The bar grows downstream and in height by continued deposition on its surface, forcing the water into the flanking channels, which, to carry the flow, deepen and cut laterally into the original banks. Such deepening locally lowers the water surface and the central bar emerges as an island which becomes stabilized by vegetation. Braiding was observed in a small river in a laboratory. Measurements of the adjustments of velocity, depth, width, and slope associated with island development lead to the conclusion that braiding is one of the many patterns which can maintain quasi-equilibrium among discharge, load, and transporting ability. Braiding does not necessarily indicate an excess of total load.Channel cross section and pattern are ultimately controlled by the

Laboratory Experiments on Meandering Meltwater Channels

NASA Astrophysics Data System (ADS)

Fernandez, R.; Berens, J.; Parker, G.; Stark, C. P.

2017-12-01

Meandering channels of all scales and flowing over a wide variety of media have common planform patterns. Although the analogy in planform suggests there is a common underlying framework, the constitutive relations driving planform evolution through vertical incision/deposition and lateral migration differ from medium to medium. The driving processes in alluvial and mixed bedrock-alluvial meandering channels have been studied substantially over the last decades. However, this is not the case for meandering channels in other media such as ice or soluble rock. Here we present results from experiments conducted at the Ven Te Chow Hydrosystems Laboratory of the University of Illinois at Urbana-Champaign on meltwater meandering channels. A rivulet is carved into an ice block and water is allowed to flow at a constant discharge. Planform evolution is analyzed with time lapse imaging and complemented with rubber molds of the channel once the experiment is over. These molds give us the full 3D structure of the meandering, including incisional overhang. Vertical incision rates are measured throughout the run by taking elevations along the channel, and these measurements are complemented with analysis from the molds. We show examples of meandering of intense amplitude with deep overhangs. Features resembling scroll bars document cyclically punctuated melting. We report on lateral migration rates, incision rates, sinuosity, channel depths, channel widths, reach averaged velocities, bend wavelengths and amplitudes and compare them to values reported in the literature for alluvial rivers.

Planform Dynamics of a Mixed Bedrock-Alluvial Meandering River

NASA Astrophysics Data System (ADS)

Rhoads, B. L.; Konsoer, K. M.; Best, J.; Garcia, M. H.; Abad, J. D.

2013-12-01

The planform evolution of meandering rivers involves dynamic interactions among planform geometry, three-dimensional flow structure, bed morphology, sediment transport, and bank resistance. Modes of interaction among these factors in different types of bends have yet to be completely determined. This paper examines flow structure, bed morphology, and planform evolution in three different types of bends on the Wabash River, Illinois: an elongated loop with forested banks and extensive bedrock at the downstream end of the bend (Horseshoe Bend), an elongated loop with unforested banks and local bedrock control within the bend (Maier Bend), and a series of simple bends with forested banks and no bedrock control. Data consist of velocity measurements obtained between May 2011 and February 2013 for bankfull or near-bankfull flows using acoustic Doppler current profilers. Rates of migration and planform evolution were determined through GIS-based analysis of historical aerial photography from 1938 to present, including annual photos in recent years. Lidar data, sediment samples, and multi-beam echosounding data provide information on bed morphology, on the spatial extent of bedrock, and on bank materials. Horseshoe Bend has not moved substantially over the historical period of record. This lack of migration is in part related to extensive bedrock control, but also reflects high near-bank flow resistance produced by LWD and the relatively high resistance of bank materials to erosion. At Maier Bend, migration rates are high due to low resistance of bank materials to erosion, resulting in bend extension; however, the pattern of extension has been strongly influenced by the local outcropping of bedrock into the channel. In the simple bends, planform evolution has been dominated by translation, despite migration of the channel into forested sections of the floodplain. Bed morphology in these bends, especially the structure of point bars, strongly influences flow structure

Complexity, self-organisation and variation in behaviour in meandering rivers

NASA Astrophysics Data System (ADS)

Hooke, J. M.

2007-11-01

River meanders are natural features on the surface of Earth that present some degree of regularity of form. They range from being highly dynamic to being stable under present conditions. Conventional theory is that meanders develop to an equilibrium form which is related to discharge and sediment load. Other research has demonstrated that many highly active meanders exhibit a continuous evolution over time and a non-linearity in rate of development. Ideas of autogenesis and of self-organised criticality as being an explanation of some meander changes have been proposed. In this paper data from rivers around the world are examined for further evidence of autogenic, self-organised or non-linear behaviour through analysis of change in sinuosity over time for reaches and change in individual bend form, particularly bend curvature and bend elongation. Some examples do exhibit trends of increasing sinuosity over time and a few show limits from which large decreases occur. Several case studies show non-linearity of behaviour and increasing complexity of form. Other case studies, however, do not exhibit such trends. Phase space plots are used to help uncover emergent behaviour but show a variety of patterns. The example of a reach in which multiple cut-offs occurred is analysed for mechanisms of self-organisation of the planform and in the pool-riffle pattern. Riffles are more closely spaced and also more transient in the more rapidly changing and higher sinuosity parts of the channel. Hypothetical trajectories of different meander behaviour, including for bedrock meanders, are plotted but the challenge remains to uncover the conditions for occurrence and for divergence of tendencies to stability and instability. Identification of attractors and phase space of behaviour of different meandering systems offer the potential for application to sustainable channel management.

Stream-power model of meander cutoff in gravel beds

NASA Astrophysics Data System (ADS)

Pannone, M.; De Vincenzo, A.

2016-12-01

In the present study we propose a one-dimensional model for the prediction of the large-time evolution of river meanders (pre-cutoff conditions) characterized by gravel bed and negligible suspended load. Due to its relatively simple structure, it may be a fast and easy tool to forecast the time evolution of a bend when the symptoms of an incipient instability suggest quantifying the time left for river exploitation as a naturalistic or a commercial resource and timely planning, if needed, the site management and restoration. Most of the previous research on meandering rivers focused on linearized theories that apply to very small bend amplitudes and very large radii of curvature. The dynamics of meander growth and cutoff was typically afforded by case-sensitive numerical simulations or by descriptive methods aimed at deriving purely empirical laws relating the hydraulics to some geomorphological parameters. The present approach combines the immediacy of a general analytical model with the accuracy of a fluid-mechanical background. The model focuses on energetic principles and interprets the mechanism of meander cutoff as the achievement of limit conditions in terms of river stream power. The corresponding analytical solution, which consists in a 1-D deterministic integro-differential equation governing the meander pre-cutoff phase, accounts for the influence of the morphological and sedimentological parameters by the downstream migration rate and the radius of the meander osculating circle. The results, expressed in terms of instable meander lifetime, are in good agreement with the data obtained from a number of field surveys documented in literature. Additionally, the proposed fluid-mechanical model allows identifying the physical mechanisms responsible for some peculiarities of large-time meander evolution like the decreasing skewness and asymmetry.

Creating self-formed meandering channels in laboratory flumes (Invited)

NASA Astrophysics Data System (ADS)

Braudrick, C. A.

2009-12-01

Our ability to construct predictive numerical models for meandering rivers is hampered by the inability to create meandering channels in the laboratory where individual variables can be isolated and controlled. Typically, experimental channels braid, straighten, or cease migration once they develop curvature. By using alfalfa sprouts to provide bank strength and fine sediment to attach point bars to the floodplain, we have successfully created and maintained meandering morphology in a laboratory flume. The 6.1 by 17 m flume has a floodplain slope of approximately 0.005 with a sandy bed and banks that scales as a gravel bed river. The alfalfa sprouts slow bank erosion allowing time for the bars to create new floodplain deposits. The sprouts also increase floodplain roughness, armor new bar deposits, and promote deposition of overbank sediment. The fine sediment, a lightweight plastic that scaled as sand, was crucial for blocking chutes formed between the bar and the floodplain, isolating cut-off channels from the main flow, and creating levees. During this 136-hour long experiment, the channel width stabilized as the channel migrated across the floodplain, and the curvature was recreated following cutoffs. Although the sinuosity (about 1.2) was low relative to meandering channels observed in the field, the spacing of bends was within the upper bounds of field examples. Subsequent experiments with higher bank strength had more limited chute development were able to generate a sinuosity of about 1.4. Scaling analysis indicates that the bank migration rates in the lower sinuosity experiment were approximately 10 times faster than migration rates in the field. A particular challenge in these experiments is maintaining a healthy alfalfa crop. After 15-20 hours of flood flows, the alfalfa begins to die off and new emergent bars need to be seeded. It then takes about 7 days for the alfalfa to grow to the size used in these experiments. The 15-20 hours scale to about one

Meandering channels without vegetation: Examples from Nevada and Chile

NASA Astrophysics Data System (ADS)

Matsubara, Y.; Howard, A. D.; Burr, D. M.; Williams, R. M.; Moore, J. M.

2012-12-01

We report on a study motivated by the occurrence of highly sinuous, actively migrating paleochannels on Mars. Highly sinuous, unconfined meanders require small aspect ratios, which in turn require cohesive channel banks. This cohesion is obtained most commonly by vegetation cover coupled with high suspended sediment loading. The dominant role of vegetation in meandering is reflected in the difficulty in creating highly sinuous channels in flume experiment without introduction of vegetation. The occurrence of strongly meandering channels on Mars suggests meanders can develop in the absence of vegetation. The main objective of our study is to understand the processes of meander evolution in non-vegetated surfaces. We have studied two terrestrial sites in which meandering channels form where vegetation is sparse and has little influence on bank erodibility or point-bar deposition, indicating that there must be other mechanisms creating bank cohesion. One mechanism is stabilization of point-bar deposits by mud drapes. The Quinn River in Nevada is a sinuous channel that flows through fine lacustrine sediments on the floor of paleolake Lahontan resulting in the river having both bed and bank composed of sediment containing least 40% silt/clay. In addition to abundant mud, high salt content of the river water encourages flocculation and settling of fine sediment; thus both high clay/silt content and salt work together at the Quinn River to maintain a small aspect ratio. In contrast to the Quinn River, meandering channels on alluvial fans in the Atacama Desert in northern Chile are deposited by flows originating from the foothills of the Andes Mountains where sediments are coarser and more variable in size. Like Quinn River both fine sediments and salts contribute to meandering. The bank cohesion is provided by mudflows or hyperconcentrated flows creating bank drapes as well as extensive overbank levees which harden to adobe-like consistency. The Atacama Desert is rich in

The Morphodynamic Signature of Rivers in the Ucamara Depression: A Habitat for Formative Rivers and the Scavenger Meandering Channels they Feed

NASA Astrophysics Data System (ADS)

Abad, J. D.; Escobar, C.; Shan, J.

2017-12-01

The Pacaya Samiria National Reserve, located in Loreto, Peru, is a region of incomparable biodiversity resulting from the consistent annual climate patterns (little seasonal variability), and more importantly, the dynamics of the freshwater rivers that surround and traverse it. The Ucamara Depression, where the Pacaya Samiria National Reserve is located, presently has a myriad of active and abandoned fluvial landforms. The exploration of the geologic and tectonic history that fabricated this exceptional fluvial system is the foundation for researching and understanding further phenomena of the region. The interpretation of the history of the geologic events that occurred to form this region and the inspection of the river belts, or areas of active river migration, of these fluvial landforms, facilitate the understanding of 1) how the Ucayali and Maranon rivers interact with one another and with the streams and bodies of water in the Ucamara Depression, 2) the role of wetlands, hydrodynamics, and sediment transport mechanisms in the movement of rivers and the extent of mixing before the rivers reach their confluence, and 3) how the water chemistry, flooding, and sediment transport processes of rivers create an environment capable of fostering an unimaginable array of life and how changes in these processes affect the flora and fauna that inhabit the region. This study will discuss field measurements (hydrodynamic and bed morphodynamic) and remote sensing analysis of scavenger meandering channels (Pacaya and Samiria) and discuss confluence dynamics of the two tributaries that form the Amazon River. Morphometric parameters show that these meandering rivers do not achieve typical planform-based conditions.

The Middle Sacramento River: Human Impacts on Physical and Ecological Processes Along a Meandering River

Treesearch

Koll Buer; Dave Forwalter; Mike Kissel; Bill Stohlert

1989-01-01

Native plant and wildlife communities along Northern California's middle Sacramento River (Red Bluff to Colusa) originally adapted to a changing pattern of erosion and deposition across a broad meander belt. The erosion-deposition process was in balance, with the river alternately building and eroding terraces. Human-induced changes to the Sacramento River,...

The life of a meander bend: Connecting shape and dynamics via analysis of a numerical model

NASA Astrophysics Data System (ADS)

Schwenk, Jon; Lanzoni, Stefano; Foufoula-Georgiou, Efi

2015-04-01

Analysis of bend-scale meandering river dynamics is a problem of theoretical and practical interest. This work introduces a method for extracting and analyzing the history of individual meander bends from inception until cutoff (called "atoms") by tracking backward through time the set of two cutoff nodes in numerical meander migration models. Application of this method to a simplified yet physically based model provides access to previously unavailable bend-scale meander dynamics over long times and at high temporal resolutions. We find that before cutoffs, the intrinsic model dynamics invariably simulate a prototypical cutoff atom shape we dub simple. Once perturbations from cutoffs occur, two other archetypal cutoff planform shapes emerge called long and round that are distinguished by a stretching along their long and perpendicular axes, respectively. Three measures of meander migration—growth rate, average migration rate, and centroid migration rate—are introduced to capture the dynamic lives of individual bends and reveal that similar cutoff atom geometries share similar dynamic histories. Specifically, through the lens of the three shape types, simples are seen to have the highest growth and average migration rates, followed by rounds, and finally longs. Using the maximum average migration rate as a metric describing an atom's dynamic past, we show a strong connection between it and two metrics of cutoff geometry. This result suggests both that early formative dynamics may be inferred from static cutoff planforms and that there exists a critical period early in a meander bend's life when its dynamic trajectory is most sensitive to cutoff perturbations. An example of how these results could be applied to Mississippi River oxbow lakes with unknown historic dynamics is shown. The results characterize the underlying model and provide a framework for comparisons against more complex models and observed dynamics.

Inverted Meandering Rivers at a Possible Future Mars Landing Site

NASA Image and Video Library

2015-11-27

This image from NASA Mars Reconnaissance Orbiter spacecraft contains interesting examples of crosscutting, sinuous and straight ridges. The ridge in the lower left of the image (orange) has gradual bends and well-defined positive relief, while the ridge in the upper right (blue) exhibits a degree of high sinuosity. Both ridges may be ancient river deposits. In the southern part of the image, there are also possible cut bank and point bar deposition scars (green), but these do not possess visible positive relief. Although lacking relief, the sinuosity of these scars implies an ancient, mature, and low-gradient meandering river. The upper right ridge exhibits a sinuous geometry with positive relief reminiscent of a mature meandering river. Cementation of by underground fluids may have given the river deposits a higher resistance to erosion compared to the surrounding flood plain. Subsequent weathering removed the deposits in the flood plain, leaving behind the river channel positive relief. Offsets of the lower left ridge along possible fault scarps (red) suggest that the area was cut by faults either during or after deposition of the river deposits. There also appears to be a less pronounced fault at the terminus of the upper right ridge. http://photojournal.jpl.nasa.gov/catalog/PIA20160

A geomorphic explanation for a meander cutoff following channel relocation of a coarse-bedded river.

PubMed

Thompson, Douglas M

2003-03-01

The Veteran's Fishing section of the Blackledge River in central Connecticut was relocated in the late 1950s. The relocation resulted in an unstable channel despite extensive efforts to prevent erosion. Overbank erosion and meander cutoffs were investigated using detailed survey data, characterizations of sediment deposits, flow modeling, and a moment-stability analysis. Limited reworking of revetment boulders indicate that riprap bank material was immobile during a 1979 flood event responsible for the formation of the cutoff channel. A moment-stability analysis factor-of-safety value of 1.1 supports the conclusion that riprap was not directly eroded from the banks. Alluvial particles with d(95) values ranging up to 120 mm were deposited along a bar downstream from the cutoff channel at flows estimated to be below a 1.5-year recurrence interval flow. Development of the bar deposit resulted in locally elevated water surfaces at high flow. The resulting overbank flow across the meander neck to the adjacent downstream bend led to the creation of an upstream migrating knickpoint, the erosion of approximately 16,000-year-old sediments, and the subsequent meander cutoff. The results of the study indicate that traditional erosion-control measures cannot prevent extreme channel adjustments if the geomorphic processes that control sediment continuity also are not considered.

Topographic Signatures of Meandering Rivers with Differences in Outer Bank Cohesion

NASA Astrophysics Data System (ADS)

Kelly, S. A.; Belmont, P.

2014-12-01

Within a given valley setting, interactions between river hydraulics, sediment, topography, and vegetation determine attributes of channel morphology, including planform, width and depth, slope, and bed and bank properties. These feedbacks also govern river behavior, including migration and avulsion. Bank cohesion, from the addition of fine sediment and/or vegetation has been recognized in flume experiments as a necessary component to create and maintain a meandering channel planform. Greater bank cohesion slows bank erosion, limiting the rate at which a river can adjust laterally and preventing so-called "runaway widening" to a braided state. Feedbacks of bank cohesion on channel hydraulics and sediment transport may thus produce distinct topographic signatures, or patterns in channel width, depth, and point bar transverse slope. We expect that in bends of greater outer bank cohesion the channel will be narrower, deeper, and bars will have greater transverse slopes. Only recently have we recognized that biotic processes may imprint distinct topographic signatures on the landscape. This study explores topographic signatures of three US rivers: the lower Minnesota River, near Mankato, MN, the Le Sueur River, south central MN, and the Fall River, Rocky Mountain National Park, CO. Each of these rivers has variability in outer bank cohesion, quantified based on geotechnical and vegetation properties, and in-channel topography, which was derived from rtkGPS and acoustic bathymetry surveys. We present methods for incorporating biophysical feedbacks into geomorphic transport laws so that models can better simulate the spatial patterns and variability of topographic signatures.

Martian Meanders and Scroll-Bars

NASA Image and Video Library

2017-03-01

This is a portion of an inverted fluvial channel in the region of Aeolis/Zephyria Plana, at the Martian equator. Channels become inverted when the sediments filling them become more resistant to erosion than the surrounding material. Here, the most likely process leading to hardening of the channel material is chemical cementation by precipitation of minerals. Once the surrounding material erodes, the channel is left standing as a ridge. The series of curvilinear lineations are ancient scroll-bars, which are features typical of river meanders (bends) in terrestrial fluvial channels. Scroll-bars are series of ridges that result from the continuous lateral migration of a meander. On Earth, they are more common in mature rivers. The presence of scroll bars suggests that the water flow in this channel may have been sustained for a relatively long time. Measuring characteristics of these scroll-bars and meanders may help to estimate the amount of water that once flowed in this channel, aiding our understanding of the history of water on Mars. The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 29.3 centimeters (11.5 inches) per pixel (with 1 x 1 binning); objects on the order of 88 centimeters (29.6 inches) across are resolved.] North is up. http://photojournal.jpl.nasa.gov/catalog/PIA21551

Geomorphic and vegetation changes in a meandering dryland river regulated by a large dam, Sauce Grande River, Argentina

NASA Astrophysics Data System (ADS)

Casado, Ana; Peiry, Jean-Luc; Campo, Alicia M.

2016-09-01

This paper investigates post-dam geomorphic and vegetation changes in the Sauce Grande River, a meandering dryland river impounded by a large water-conservation dam. As the dam impounds a river section with scarce influence of tributaries, sources for fresh water and sediment downstream are limited. Changes were inspected based on (i) analysis of historical photographs/imagery spanning pre- (1961) and post-dam (1981, 2004) channel conditions for two river segments located above and below the dam, and (ii) field survey of present channel conditions for a set of eight reference reaches along the river segments. Whilst the unregulated river exhibited active lateral migration with consequent adjustments of the channel shape and size, the river section below the dam was characterized by (i) marked planform stability (93 to 97%), and by (ii) vegetation encroachment leading to alternating yet localized contraction of the channel width (up to 30%). The present river displays a moribund, stable channel where (i) redistribution of sediment along the river course no longer occurs and (ii) channel forms constitute a remnant of a fluvial environment created before closing the dam, under conditions of higher energy. In addition to providing new information on the complex geomorphic response of dryland rivers to impoundment, this paper represents the very first geomorphic assessment of the regulated Sauce Grande and therefore provides an important platform to underpin further research assessing the geomorphic state of this highly regulated dryland river.

The use of GIS tools in determining the intensity of meandering of rivers based on the example of Noteć River (Poland)

NASA Astrophysics Data System (ADS)

Szatten, Dawid; Rabant, Hubert; Nadolny, Grzegorz

2017-11-01

The study used the tools of Geographic Information System (GIS) in the analysis of the intensity of meandering of Noteć River, calculated using indicators proposed by Brice [16], Leopold et al. [17], Rust [15] and Rosgen [18]. In this work the emphasis is placed on showing the suitability of using modelling software and spatial data. The study was based on archival cartographic materials and orthophotomap presenting the current course of the river channel. The software of geographic information system used for analysis was ArcMap v.10.0. The rate of meandering of the river in a multiyear period 1876-2013 and four typical scenarios of the development of river channel were determined. Comparing them with the types of human intervention in the fluvial system, the dynamics of transformation channel in the analysed period of time was specified. These types are characteristic for all the meandering rivers. These scenarios can determine the amount of anthropopressure and to evaluate the usefulness of GIS in the analysis of transformations of the fluvial system.

The potential for dams to impact lowland meandering river floodplain geomorphology.

PubMed

Marren, Philip M; Grove, James R; Webb, J Angus; Stewardson, Michael J

2014-01-01

The majority of the world's floodplains are dammed. Although some implications of dams for riverine ecology and for river channel morphology are well understood, there is less research on the impacts of dams on floodplain geomorphology. We review studies from dammed and undammed rivers and include influences on vertical and lateral accretion, meander migration and cutoff formation, avulsion, and interactions with floodplain vegetation. The results are synthesized into a conceptual model of the effects of dams on the major geomorphic influences on floodplain development. This model is used to assess the likely consequences of eight dam and flow regulation scenarios for floodplain geomorphology. Sediment starvation downstream of dams has perhaps the greatest potential to impact on floodplain development. Such effects will persist further downstream where tributary sediment inputs are relatively low and there is minimal buffering by alluvial sediment stores. We can identify several ways in which floodplains might potentially be affected by dams, with varying degrees of confidence, including a distinction between passive impacts (floodplain disconnection) and active impacts (changes in geomorphological processes and functioning). These active processes are likely to have more serious implications for floodplain function and emphasize both the need for future research and the need for an "environmental sediment regime" to operate alongside environmental flows.

The Potential for Dams to Impact Lowland Meandering River Floodplain Geomorphology

PubMed Central

Marren, Philip M.; Grove, James R.; Webb, J. Angus; Stewardson, Michael J.

2014-01-01

The majority of the world's floodplains are dammed. Although some implications of dams for riverine ecology and for river channel morphology are well understood, there is less research on the impacts of dams on floodplain geomorphology. We review studies from dammed and undammed rivers and include influences on vertical and lateral accretion, meander migration and cutoff formation, avulsion, and interactions with floodplain vegetation. The results are synthesized into a conceptual model of the effects of dams on the major geomorphic influences on floodplain development. This model is used to assess the likely consequences of eight dam and flow regulation scenarios for floodplain geomorphology. Sediment starvation downstream of dams has perhaps the greatest potential to impact on floodplain development. Such effects will persist further downstream where tributary sediment inputs are relatively low and there is minimal buffering by alluvial sediment stores. We can identify several ways in which floodplains might potentially be affected by dams, with varying degrees of confidence, including a distinction between passive impacts (floodplain disconnection) and active impacts (changes in geomorphological processes and functioning). These active processes are likely to have more serious implications for floodplain function and emphasize both the need for future research and the need for an “environmental sediment regime” to operate alongside environmental flows. PMID:24587718

Reductionist versus holistic approaches to the study of river meandering: An ideal dialogue

NASA Astrophysics Data System (ADS)

Seminara, G.; Pittaluga, M. Bolla

2012-08-01

We discuss some recent attempts to apply the theory of nonlinear dynamical systems to the interpretation of the long term morphodynamic evolution of meandering rivers. To make the discussion attractive for the reader, we employ the method of a Socratic dialogue between a member of the so called 'reductionist community', who is inclined to support only theories based on physical principles and who is skeptical about fashionable new paradigms, and a member of the 'holistic community', who supports the idea that new paradigms are needed because rivers are complex systems, whose response can only be interpreted using tools that analyze the system "as a whole". The dialogue focuses on a selection of recent contributions which assesses the progress in understanding of meander dynamics achieved by the use of the above new paradigms. The discussion suggests that some consensus has been reached on the fractal nature of meandering patterns, with the fractal dimension playing the role of a morphometric parameter. On the contrary, despite different early suggestions, recent thorough analysis has been unable to detect any clear evidence that the evolution of meanders displays the characters of either a chaotic or a self organized critical process. The dialogue is concluded with some consensus on the perspective that well founded cellular models may possibly help reconciling the reductionist and holistic viewpoints.

The bankfull hydraulic geometry of evolving meander bends

NASA Astrophysics Data System (ADS)

Monegaglia, F.; Tubino, M.; Zolezzi, G.

2017-12-01

Changes in the bankfull hydraulic geometry of meandering rivers associated with meander growth from incipient meandering to cutoffs have seldom been analysed in detail. Such information is also needed by meander morphodynamic models, most of which simulate the evolution of bankfull channel geometry by simply accounting for channel slope reduction inversely proportional to elongation, while changes in bankfull channel width are often neglected or, when they are considered, they are not consistent with the few available observations. To address these gaps we first perform an extensive, systematic, bend-scale evolutionary analysis of bankfull channel widths in several large meandering rivers in the Amazon basin, over a three decades time period, from remotely sensed field data. The analysis consistently show a slight decreasing trend of the bankfull channel width during the planform evolution towards cutoff. Furthermore, we develop a physically based model for the evolution of bankfull channel geometry during the planform development of meandering rivers. The model is based on the conservation of sediment discharge. An integrated one-dimensional Exner equation that accounts for meander elongation, sediment supply conservation and sediment income from the channel banks, allows us to predict the evolution of the channel slope. The evolution of the channel width is modeled through a threshold equation. The model correctly predicts the slight variability of channel width during meander development and a gentler reduction of the channel slope, which is mitigated by the conservation of sediment supply. The bankfull geometry of highly dynamic meandering rivers is predicted to be elongation-dominated, while the one related to slowly evolving meandering rivers is sediment supply-dominated. Finally, we discuss the implications of the proposed modeling framework in terms of planform structure, meander shape and morphodynamic influence.

Sediment Transport Dynamic in a Meandering Fluvial System: Case Study of Chini River

NASA Astrophysics Data System (ADS)

Nazir, M. H. M.; Awang, S.; Shaaban, A. J.; Yahaya, N. K. E. M.; Jusoh, A. M.; Arumugam, M. A. R. M. A.; Ghani, A. A.

2016-07-01

Sedimentation in river reduces the flood carrying capacity which lead to the increasing of inundation area in the river basin. Basic sediment transport can predict the fluvial processes in natural rivers and stream through modeling approaches. However, the sediment transport dynamic in a small meandering and low-lying fluvial system is considered scarce in Malaysia. The aim of this study was to analyze the current riverbed erosion and sedimentation scenarios along the Chini River, Pekan, Pahang. The present study revealed that silt and clay has potentially been eroded several parts of the river. Sinuosity index (1.98) indicates that Chini River is very unstable and continuous erosion process in waterways has increase the riverbank instability due to the meandering factors. The riverbed erosional and depositional process in the Chini River is a sluggish process since the lake reduces the flow velocity and causes the deposited particles into the silt and clay soil at the bed of the lake. Besides, the bed layer of the lake comprised of cohesive silt and clayey composition that tend to attach the larger grain size of sediment. The present study estimated the total sediment accumulated along the Chini River is 1.72 ton. The HEC-RAS was employed in the simulations and in general the model performed well, once all parameters were set within their effective ranges.

Exploring the role of trees in the evolution of meander bends: The Tagliamento River, Italy

NASA Astrophysics Data System (ADS)

Zen, Simone; Gurnell, Angela M.; Zolezzi, Guido; Surian, Nicola

2017-07-01

To date, the role of riparian trees in the formation of scroll bars, ridges, and swales during the evolution of meandering channels has been inferred largely from field observations with support from air photographs. In situ field observations are usually limited to relatively short periods of time, whereas the evolution of these morphological features may take decades. By combining field observations of inner bank morphology and overlying riparian woodland structure with a detailed historical analysis of airborne LiDAR data, panchromatic, and color images, we reconstruct the spatial and temporal evolution of the morphology and vegetation across four meander bends of the Tagliamento River, Italy. Specifically we reveal (i) the appearance of deposited trees and elongated vegetated patches on the inner bank of meander bends following flood events; (ii) temporal progression from deposited trees, through small to larger elongated vegetated patches (pioneer islands), to their coalescence into long, linear vegetated features that eventually become absorbed into the continuous vegetation cover of the riparian forest; and (iii) a spatial correspondence between the resulting scrolls and ridge and swale topography, and tree cover development and persistence. We provide a conceptual model of the mechanisms by which vegetation can contribute to the formation of sequence of ridges and swales on the convex bank of meander bends. We discuss how these insights into the biomorphological processes that control meander bends advance can inform modeling activities that aim to describe the lateral and vertical accretion of the floodplain during the evolution of vegetated river meanders.

Computer simulations of channel meandering and the formation of point bars: Linking channel dynamics to the preserved stratigraphy

NASA Astrophysics Data System (ADS)

Sun, T.; Covault, J. A.; Pyrcz, M.; Sullivan, M.

2012-12-01

Meandering rivers are probably one of the most recognizable geomorphic features on earth. As they meander across alluvial and delta plains, channels migrate laterally and develop point bars, splays, levees and other geomorphic and sedimentary features that compose substantial portions of the fill within many sedimentary basins. These basins can include hydrocarbon producing fields. Therefore, a good understanding of the processes of meandering channels and their associated deposits is critical for exploiting these reservoirs in the subsurface. In the past couple of decades, significant progress has been made in our understanding of the morphodynamics of channel meandering. Basic fluid dynamics and sediment transport (Ikeda and Parker, 1981; Howard, 1992) has shown that many characteristic features of meandering rivers, such as the meandering wavelength, growth rate and downstream migration rate, can be predicted quantitatively. As a result, a number of variations and improvement of the theory have emerged (e.g., Blondeaux and Seminara, 1985; Parker and Andrews, 1985, 1986; and Sun et al., 2001a, b).The main improvements include the recognition of so called "bar-bend" interactions, where the development of bars on the channel bed and their interactions with the channel bend is recognized as a primary cause for meandering channels to develop greater complexity than the classic goose-neck meander bend shapes, such as compound bend. Recently, Sun and others have shown that the spatial patterns of width variations in meandering channels can be explained by an extrinsic periodic flow variations coupled with the intrinsic bend instability dynamics. In contrast to the significant improvement of our understanding of channel meandering, little work has been done to link the geomorphic features of meandering channels to the geometry and heterogeneity of the deposits they form and ultimately preserves. A computer simulation model based on the work of Sun and others (1996, 2001

Analysis of river planforms in the New Madrid region and possible relations to tectonic warping across the loess bluffs and within the meander belt of the Mississippi River

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, K.A.; Mayer, L.

1993-03-01

Stream channel planforms measured from such streams as the Hatchie (H), L'Anguille (LA), St. Francis, White (W) and Little Red (LR) rivers provide a way to study influences of topographic warping between the loess bluffs that bound the Mississippi river valley. Planforms are analyzed using sinuosity, Richardson analysis, and pattern. Pattern changes include transitions from braided to meandering and meandering to straight. Sinuosities of the W and LR rivers show a transition from low sinuosity, [1.3, 1.4] to higher sinuosity [2.6, 2.8], over a short distance, as they cross the bluffs from the uplands to the Western Lowlands. On themore » east, the Hatchie changes from a braided to meandering pattern upon crossing the bluffs. Its sinuosity varies from a low of about 1.4 to a high of 2.2, coincident with a marsh area. The LA river flows on the west side of Crowley's Ridge and is paralleled by the St. Francis river on the east. These rivers, with very different drainage areas and sinuosities, show matching meander bends at similar wavelengths along Crowley's Ridge. The bends are about 10 km in 1/2 wavelength suggesting some extraordinary influence on pattern perpendicular to the ridge. Richardson analysis indicates that features with a 1/2 wavelength of 2 km may control several rivers' bending patterns. These features are analyzed to determine their spatial relations with one another.« less

The linkage between fluvial meander-belt morphodynamics and the depositional record improves paleoenvironmental interpretations, Western Interior Basin, Alberta, Canada

NASA Astrophysics Data System (ADS)

Durkin, P.; Hubbard, S. M.

2016-12-01

Enhanced stratigraphic interpretations are possible when linkages between morphodynamic processes and the depositional record are resolved. Recent studies of modern and ancient meander-belt deposits have emphasized morphodynamic processes that are commonly understated in the analysis of stratigraphic products, such as intra-point bar erosion and rotation, counter-point-bar (concave bank-bench) development and meander-bend abandonment. On a larger scale, longitudinal changes in meander-belt morphology and processes such as changes in meander-bend migration rate, channel-belt width/depth ratio and sinuosity have been observed as rivers flow through the tidal backwater zone. However, few studies have attempted to recognize the impact of the backwater zone in the stratigraphic record. We consider ancient meander-belt deposits of the Cretaceous McMurray Formation and document linkages between morphodynamic processes and their stratigraphic product to resolve more detailed paleoenvironmental interpretations. The ancient meander belt was characterized by paleochannels that were 600 m wide and up to 50 m deep, resolved in a particularly high quality subsurface dataset consisting of 600 km2 of high-quality 3-D seismic data and over 1000 wellbores. A 3-D geocellular model and reconstructed paleochannel migration patterns reveal the evolutionary history of seventeen individual meander belt elements, including point bars, counter point bars and their associated abandoned channel fills. At the meander-bend scale, intra-point-bar erosion surfaces bound accretion packages characterized by unique accretion directions, internal stratigraphic architecture and lithologic properties. Erosion surfaces and punctuated bar rotation are linked to upstream changes in channel planform geometry (meander cut-offs). We provide evidence for downstream translation and development of counter-point bars that formed in response to valley-edge and intra-meander-belt confinement. At the meander

Sediment storage time in a simulated meandering river's floodplain, comparisons of point bar and overbank deposits

NASA Astrophysics Data System (ADS)

Ackerman, T. R.; Pizzuto, J. E.

2016-12-01

Sediment may be stored briefly or for long periods in alluvial deposits adjacent to rivers. The duration of sediment storage may affect diagenesis, and controls the timing of sediment delivery, affecting the propagation of upland sediment signals caused by tectonics, climate change, and land use, and the efficacy of watershed management strategies designed to reduce sediment loading to estuaries and reservoirs. Understanding the functional form of storage time distributions can help to extrapolate from limited field observations and improve forecasts of sediment loading. We simulate stratigraphy adjacent to a modeled river where meander migration is driven by channel curvature. The basal unit is built immediately as the channel migrates away, analogous to a point bar; rules for overbank (flood) deposition create thicker deposits at low elevations and near the channel, forming topographic features analogous to natural levees, scroll bars, and terraces. Deposit age is tracked everywhere throughout the simulation, and the storage time is recorded when the channel returns and erodes the sediment at each pixel. 210 ky of simulated run time is sufficient for the channel to migrate 10,500 channel widths, but only the final 90 ky are analyzed. Storage time survivor functions are well fit by exponential functions until 500 years (point bar) or 600 years (overbank) representing the youngest 50% of eroded sediment. Then (until an age of 12 ky, representing the next 48% (point bar) or 45% (overbank) of eroding sediment), the distributions are well fit by heavy tailed power functions with slopes of -1 (point bar) and -0.75 (overbank). After 12 ky (6% of model run time) the remainder of the storage time distributions become exponential (light tailed). Point bar sediment has the greatest chance (6%) of eroding at 120 years, as the river reworks recently deposited point bars. Overbank sediment has an 8% chance of eroding after 1 time step, a chance that declines by half after 3

River meanders and channel size

USGS Publications Warehouse

Williams, G.P.

1986-01-01

This study uses an enlarged data set to (1) compare measured meander geometry to that predicted by the Langbein and Leopold (1966) theory, (2) examine the frequency distribution of the ratio radius of curvature/channel width, and (3) derive 40 empirical equations (31 of which are original) involving meander and channel size features. The data set, part of which comes from publications by other authors, consists of 194 sites from a large variety of physiographic environments in various countries. The Langbein-Leopold sine-generated-curve theory for predicting radius of curvature agrees very well with the field data (78 sites). The ratio radius of curvature/channel width has a modal value in the range of 2 to 3, in accordance with earlier work; about one third of the 79 values is less than 2.0. The 40 empirical relations, most of which include only two variables, involve channel cross-section dimensions (bankfull area, width, and mean depth) and meander features (wavelength, bend length, radius of curvature, and belt width). These relations have very high correlation coefficients, most being in the range of 0.95-0.99. Although channel width traditionally has served as a scale indicator, bankfull cross-sectional area and mean depth also can be used for this purpose. ?? 1986.

Sediment supply as a driver of river evolution in the Amazon Basin

NASA Astrophysics Data System (ADS)

Ahmed, Joshua; Constantine, José Antonio; Dunne, Thomas; Legleiter, Carl; Lazarus, Eli D.

2015-04-01

The Amazon represents the only large river basin in the world where there is a sufficient range of sediment supplies and a lack of engineering controls to assess how sediment supply drives the evolution of meandering rivers. Despite recent analytical advances (Asahi et al., 2013; Pittaluga and Seminara, 2011), modern theory does not yet identify or explain the effects of externally imposed sediment supplies, a fundamental river characteristic, on meandering river evolution. These sediment supplies would be radically reduced by the construction of large dams proposed for the Amazon Basin (Finer and Jenkins, 2012). Here, we demonstrate that the sediment loads imposed by their respective drainage basins determine planform changes in lowland rivers across the Amazon. Our analysis, based on Landsat image sequences, indicates that rivers with high sediment loads draining the Andes and associated foreland basin experience annual migration rates that are on average four times faster than rivers with lower sediment loads draining the Central Amazon Trough and shields. Incidents of meander cutoff also occur more frequently along the rivers of the Andes and foreland basin, where the number of oxbows in the floodplains is more than twice that observed in the floodplains of the Central Amazon Trough and shields. Our results, which cannot be explained by differences in channel slope or hydrology, highlight the importance of sediment supply in modulating the ability of meandering alluvial rivers to reshape the floodplain environment through river migration. Asahi, K., Shimizu, Y., Nelson, J., Parker, G., 2013. Numerical simulation of river meandering with self-evolving banks. Journal of Geophysical Research: Earth Surface, 118(4), 2013JF002752. Finer, M., Jenkins, C.N., 2012. Proliferation of hydroelectric dams in the Andean Amazon and implications for Andes-Amazon connectivity. PLOS One, 7(4), e35126. Pittaluga, M.B., Seminara, G., 2011. Nonlinearity and unsteadiness in river

Coupling MAST-1D, a sediment routing model for channel-floodplain complexes, with channel migration relationships to predict reach-averaged river morphodynamics. Preliminary results

NASA Astrophysics Data System (ADS)

Viparelli, E.; Eke, E. C.; Lauer, J. W.

2017-12-01

Sediment exchange between the channel and floodplain can occur via meander migration, overbank deposition or erosion, and changes in channel geometry. Depending on channel and floodplain history, floodplains can act either as sources or sinks of bed material and/or wash load. Here we present preliminary modeling results that explicitly account for the feedbacks between the changes in floodplain geometry and sediment size distribution and the changes in channel geometry and migration. These results are obtained by coupling the Morphodynamics And Sediment Tracers in 1D (MAST-1D) program with the results of meander migration studies linking the bankfull flow depth and mean velocity to channel migration, sinuosity and channel geometry. MAST-1D is a numerical model built to describe grain size specific transport of sediment and tracers and the long-term - i.e. decadal and longer - evolution of channel floodplain complexes. MAST-1D differs from other 1D numerical models because it allows for 1) uneven exchange of sediment and tracers between the river channel and the floodplain, 2) temporal changes in channel geometry, bed elevation and floodplain thickness, which result in changes in the channel hydraulic capacity, and 3) temporal changes of size distribution and tracer content in the floodplain, in the load and in the underlying substrate. Under conditions of constant base level, water and sediment supply, the system evolves toward a steady state wherein the amount of sediment deposited through point bar deposition and overbank sedimentation is balanced by the erosion of sediment from the floodplain through lateral migration. The current formulation couples MAST-1D with empirical channel migration relationships that link bankfull flow depth and mean velocity to channel migration, sinuosity and channel geometry. Future development of this preliminary work will involve a fully coupled MAST-1D model with a standard meander migration model that will allow for the building

Neotectonic effects on sinuosity and channel migration, Belle Fourche River, Western South Dakota

USGS Publications Warehouse

Gomez, Basil; Marron, Donna C.

1991-01-01

Short-term instability in the behaviour of a small, meandering alluvial channel is identified from the relation between sinuosity and either floodplain slope or channel slope within 17 reaches along an 81-kilometre section of the Belle Fourche River in western South Dakota. In reaches 1 to 4 and 11 to 17 the channel is relatively stable and sinuosity varies inversely with channel slope. In reaches 5 to 10, sinuosity is positively related to floodplain slope. Sinuosity increases markedly in reaches 5, 6, and 7 (which are immediately downstream from a discontinuity in the long profile of the floodplain) in association with an increase in floodplain slope. Immediately upstream from the discontinuity, bankfull channel depth and sinuosity decrease and the area of the floodplain reworked by meander migration between 1939 and 1981 increases, in association with a decrease in floodplain slope. Channel behaviour in reaches 5 to 10 is best explained as a consequence of neotectonic activity, as indicated by changes in elevation recorded along geodetic survey lines that cross lineaments that may delimit the eastern boundary of the Black Hills uplift. Sinuosity acts as a barometer of the effects of neotectonic activity on alluvial channels. Initial indications of channel and floodplain instability due to neotectonic activity may be derived from evidence of anomalously active channel migration, as documented from photographic or topographic sources.

Characterizing and modelling river channel migration rates at a regional scale: Case study of south-east France.

PubMed

Alber, Adrien; Piégay, Hervé

2017-11-01

An increased awareness by river managers of the importance of river channel migration to sediment dynamics, habitat complexity and other ecosystem functions has led to an advance in the science and practice of identifying, protecting or restoring specific erodible corridors across which rivers are free to migrate. One current challenge is the application of these watershed-specific goals at the regional planning scales (e.g., the European Water Framework Directive). This study provides a GIS-based spatial analysis of the channel migration rates at the regional-scale. As a case study, 99 reaches were sampled in the French part of the Rhône Basin and nearby tributaries of the Mediterranean Sea (111,300 km 2 ). We explored the spatial correlation between the channel migration rate and a set of simple variables (e.g., watershed area, channel slope, stream power, active channel width). We found that the spatial variability of the channel migration rates was primary explained by the gross stream power (R 2  = 0.48) and more surprisingly by the active channel width scaled by the watershed area. The relationship between the absolute migration rate and the gross stream power is generally consistent with the published empirical models for freely meandering rivers, whereas it is less significant for the multi-thread reaches. The discussion focused on methodological constraints for a regional-scale modelling of the migration rates, and the interpretation of the empirical models. We hypothesize that the active channel width scaled by the watershed area is a surrogate for the sediment supply which may be a more critical factor than the bank resistance for explaining the regional-scale variability of the migration rates. Copyright © 2016 Elsevier Ltd. All rights reserved.

Interactions between hyporheic flow produced by stream meanders, bars, and dunes

USGS Publications Warehouse

Stonedahl, Susa H.; Harvey, Judson W.; Packman, Aaron I.

2013-01-01

Stream channel morphology from grain-scale roughness to large meanders drives hyporheic exchange flow. In practice, it is difficult to model hyporheic flow over the wide spectrum of topographic features typically found in rivers. As a result, many studies only characterize isolated exchange processes at a single spatial scale. In this work, we simulated hyporheic flows induced by a range of geomorphic features including meanders, bars and dunes in sand bed streams. Twenty cases were examined with 5 degrees of river meandering. Each meandering river model was run initially without any small topographic features. Models were run again after superimposing only bars and then only dunes, and then run a final time after including all scales of topographic features. This allowed us to investigate the relative importance and interactions between flows induced by different scales of topography. We found that dunes typically contributed more to hyporheic exchange than bars and meanders. Furthermore, our simulations show that the volume of water exchanged and the distributions of hyporheic residence times resulting from various scales of topographic features are close to, but not linearly additive. These findings can potentially be used to develop scaling laws for hyporheic flow that can be widely applied in streams and rivers.

Earth meandering

NASA Astrophysics Data System (ADS)

Asadiyan, H.; Zamani, A.

2009-04-01

In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety East Ridge (geotectonic axis GA), this system with applying torsion field (likes geomagnetic field) in side direction from Rocky Mt. (west geotectonic pole WGP) to Tibetan plateau TP (east geotectonic pole EGP),it seems that pulled mass from WGP and pushed it in EGP due to it's rolling dynamics. According to this idea we see in topographic map that North America and Green land like a tongue pulled from Pacific mouth toward TP. Actually this system rolled or meander the earth over itself fractaly from small scale to big scale and what we see in the river meandering and Earth meandering are two faces of one coin. River transport water and sediments from high elevation to lower elevation and also in EM, mass transport from high altitude-Rocky Mt. to lower altitude Himalaya Mt. along 'S' shape geodetic line-optimum path which connect points from high altitude to lower altitude as kind of Euler Elastica(EE). These curves are responsible for mass spreading (source) and mass concentration (sink). In this regard, tiltness of earth spin axis plays an important role, 'S' are part of sigmoidal shape which formed due to intersection of Earth rolling with the Earth glob and actual feature of transform fault and river meandering. Longitudinal profile in mature rivers as a part of 'S' curve also is a kind of EE. 'S' which bound the whole earth is named S-1(S order 1) and cube corresponding to this which represent Earth fracturing in global scale named C-1(cube order 1 or side vergence cube SVC), C-1 is a biggest cycle of spiral polygon, so it is not completely closed and it has separation about diameter of C-7. Inside SVC we introduce cone

Two case studies in river naturalization: planform migration and bank erosion control

NASA Astrophysics Data System (ADS)

Abad, J. D.; Guneralp, I.; Rhoads, B. L.; Garcia, M. H.

2005-05-01

A sound understanding of river planform evolution and bank erosion control, along with integration of expertise from several disciplines is required for the development of predictive models for river naturalization. Over the last few years, several methodologies have been presented for naturalization projects, from purely heuristic to more advanced methods. Since the time and space scales of concern in naturalization vary widely, there is a need for appropriate tools at a variety of time and space scales. This study presents two case studies at different scales. The first case study describes the prediction of river planform evolution for a remeandering project based on a simplified two-dimensional hydrodynamic model. The second case study describes the applicability of a Computational Fluid Dynamics (CFD) model for evaluating the effectiveness of bank-erosion control structures in individual meander bends. Understanding the hydrodynamic influence of control structures on flow through bends allows accurate prediction of depositional and erosional distribution patterns, resulting in better assessment on river planform stability, especially for the case of natural complex systems. The first case study introduces a mathematical model for evolution of meandering rivers that can be used in remeandering projects. In United States in particular, several rivers have been channelized in the past causing environmental and ecological problems. Following Newton's third law, "for every action, there is a reaction", naturalization techniques evolve as natural reactive solutions to channelization. This model (herein referred as RVR Meander) can be used as a stand-alone Windows application or as module in a Geographic Information System. The model was applied to the Poplar Creek re-meanderization project and used to evaluate re-meandering alternatives for an approximately 800-meter long reach of Poplar Creek that was straightened in 1938. The second case study describes a

River morphodynamics from space: the Landsat frontier

NASA Astrophysics Data System (ADS)

Schwenk, Jon; Khandelwal, Ankush; Fratkin, Mulu; Kumar, Vipin; Foufoula-Georgiou, Efi

2017-04-01

NASA's Landsat family of satellites have been observing the entire globe since 1984, providing over 30 years of snapshots with an 18 day frequency and 30 meter resolution. These publicly-available Landsat data are particularly exciting to researchers interested in river morphodynamics, who are often limited to use of historical maps, aerial photography, and field surveys with poor and irregular time resolutions and limited spatial extents. Landsat archives show potential for overcoming these limitations, but techniques and tools for accurately and efficiently mining the vault of scenes must first be developed. In this PICO presentation, we detail the problems we encountered while mapping and quantifying planform dynamics of over 1,300 km of the actively-migrating, meandering Ucayali River in Peru from Landsat imagery. We also present methods to overcome these obstacles and introduce the Matlab-based RivMAP (River Morphodynamics from Analysis of Planforms) toolbox that we developed to extract banklines and centerlines, compute widths, curvatures, and angles, identify cutoffs, and quantify planform changes via centerline migration and erosion/accretion over large spatial domains with high temporal resolution. Measurement uncertainties were estimated by analyzing immobile, abandoned oxbow lakes. Our results identify hotspots of planform changes, and combined with limited precipitation, stage, and topography data, we parse three simultaneous controls on river migration: climate, sediment, and meander cutoff. Overall, this study demonstrates the vast potential locked within Landsat archives to identify multi-scale controls on river migration, observe the co-evolution of width, curvature, discharge, and migration, and discover and develop new geomorphic insights.

Meanders in Ridge Form in the Zephyria Region

NASA Image and Video Library

2015-11-05

In this image from NASA Mars Reconnaissance Orbiter spacecraft, an ancient sinuous meandering river system is surrounded by features called yardangs. The yardangs are the ridge-like landforms that align approximately north-south. These features were created as the wind scoured and eroded the bedrock. The raised relief of the meandering river suggests inverted topography, likely due to lithification and cementation of the riverbed sediment. The cemented channel deposits were resistant, and thus less susceptible to erosion over time. However, the area surrounding the riverbed suggests that this area was a floodplain of weaker lithology that was subsequently eroded and shaped to the yardangs. The main meandering inverted riverbed within the image has a length of about 13 kilometers. The elevation of the channel at the top of the image is on the order of 113 meters higher than the bottom, based on Mars Orbiter Laser Altimeter (MOLA) data. This elevation difference and the increase in sinuosity of the channel shape in the southerly direction implies that the flow of the ancient river may have been heading south-southwest. http://photojournal.jpl.nasa.gov/catalog/PIA20047

Rate estimates for lateral bedrock erosion based on radiocarbon ages, Duck River, Tennessee

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brakenridge, G.R.

Rates of bedrock erosion in ingrown meandering rivers can be inferred from the location of buried relict flood-plain and river-bank surfaces, associated paleosols, and radiocarbon dates. Two independent methods are used to evaluate the long-term rates of limestone bedrock erosion by the Duck River. Radiocarbon dates on samples retrieved from buried Holocene flood-plain and bank surfaces indicate lateral migration of the river bank at average rates of 0.6-1.9 m/100 yr. Such rates agree with lateral bedrock cliff erosion rates of 0.5-1.4 m/100 yr, as determined from a comparison of late Pleistocene and modern bedrock cliff and terrace scarp positions. Thesemore » results show that lateral bedrock erosion by this river could have occurred coevally with flood-plain and terrace formation and that the resulting evolution of valley meander bends carved into bedrock is similar in many respects to that of channel meanders cut into alluvium. 11 references, 5 figures.« less

Field Investigation of Flow Structure and Channel Morphology at Confluent-Meander Bends

NASA Astrophysics Data System (ADS)

Riley, J. D.; Rhoads, B. L.

2007-12-01

The movement of water and sediment through drainage networks is inevitably influenced by the convergence of streams and rivers at channel confluences. These focal components of fluvial systems produce a complex hydrodynamic environment, where rapid changes in flow structure and sediment transport occur to accommodate the merging of separate channel flows. The inherent geometric and hydraulic change at confluences also initiates the development of distinct geomorphic features, reflected in the bedform and shape of the channel. An underlying assumption of previous experimental and theoretical models of confluence dynamics has been that converging streams have straight channels with angular configurations. This generalized conceptualization was necessary to establish confluence planform as symmetrical or asymmetrical and to describe subsequent flow structure and geomorphic features at confluences. However, natural channels, particularly those of meandering rivers, curve and bend. This property and observation of channel curvature at natural junctions have led to the hypothesis that natural stream and river confluences tend to occur on the concave outer bank of meander bends. The resulting confluence planform, referred to as a confluent-meander bend, was observed over a century ago but has received little scientific attention. This paper examines preliminary data on three-dimensional flow structure and channel morphology at two natural confluent-meander bends of varying size and with differing tributary entrance locations. The large river confluence of the Vermilion River and Wabash River in west central Indiana and the comparatively small junction of the Little Wabash River and Big Muddy Creek in southeastern Illinois are the location of study sites for field investigation. Measurements of time-averaged three-dimensional velocity components were obtained at these confluences with an acoustic Doppler current profiler for flow events with differing momentum ratios. Bed

Testing the Role of Meander Cutoff in Promoting Gene Flow across a Riverine Barrier in Ground Skinks (Scincella lateralis)

PubMed Central

Jackson, Nathan D.; Austin, Christopher C.

2013-01-01

Despite considerable attention, the long-term impact of rivers on species diversification remains uncertain. Meander loop cutoff (MLC) is one river phenomenon that may compromise a river’s diversifying effects by passively transferring organisms from one side of the river to the other. However, the ability of MLC to promote gene flow across rivers has not been demonstrated empirically. Here, we test several predictions of MLC-mediated gene flow in populations of North American ground skinks (Scincella lateralis) separated by a well-established riverine barrier, the Mississippi River: 1) individuals collected from within meander cutoffs should be more closely related to individuals across the river than on the same side, 2) individuals within meander cutoffs should contain more immigrants than individuals away from meander cutoffs, 3) immigration rates estimated across the river should be highest in the direction of the cutoff event, and 4) the distribution of alleles native to one side of the river should be better predicted by the historical rather than current path of the river. To test these predictions we sampled 13 microsatellite loci and mitochondrial DNA from ground skinks collected near three ancient meander loops. These predictions were generally supported by genetic data, although support was stronger for mtDNA than for microsatellite data. Partial support for genetic divergence of samples within ancient meander loops also provides evidence for the MLC hypothesis. Although a role for MLC-mediated gene flow was supported here for ground skinks, the transient nature of river channels and morphologies may limit the long-term importance of MLC in stemming population divergence across major rivers. PMID:23658778

2D and 3D numerical simulations of morphodynamics structures in a large-amplitude meanders

USDA-ARS?s Scientific Manuscript database

In the pioneering study of the Ishikari River, Japan, Kinoshita (Kinoshita 1957, 1961) described two types of meandering channels: (1) channel with two bars per meander wavelength (one bar per bend), and (2) channel with three or more bars per meander wavelength (multiple bars per bend). Based on th...

How Do Morphodynamic Signatures Vary Along the Ucayali, a Large Transitional River?

NASA Astrophysics Data System (ADS)

Dauer, K.; Frias, C. E.; Abad, J. D.; Paredes, J.; Vizcarra, J.; Holguin, C.

2013-12-01

The Ucayali River, with an average discharge of 11, 260 m3 ● s-1 at the Requena station, is one of the largest rivers in Peru, and at its confluence with the Maranon River, the Amazon River is born. The Ucayali River transitions from purely meandering to quasi-anabranching planform near the confluence with the Marañon River. In addition, it carries large amounts of suspended sediment and has been shown to display high rates of migration. Prompted by evidence of changing trends in rainfall and discharge in the Amazon basin, where the Ucayali is located, we have performed a baseline characterization of the planform metrics, thus to determine if effects of climatic change on the morphodynamics are happening in this transitional river, which is a vital transportation route for cities in the jungle such as Iquitos, Peru. Herein, the morphodynamics of the Ucayali River are characterized from its upstream end in Atalaya, Peru to its confluence with the Marañon near Nauta City. First, the migration rates along the Ucayali River are calculated from temporal Landsat images. Then migration rates and planform characteristics, such as wavelength and sinuosity, along the river are compared with the slope along the river to distinguish spatial dominant scales. In addition, bathymetry and velocity measurements taken in 2013 along the Ucayali River help us to understand the complex morphodynamics of the river. Specific case studies have been done at Pucallpa and Jenaro-Herrera, Peru using hydrodynamic and bathymetric measurements complemented with high-resolution shallow water modeling to understand the process of cutoff formation in different locations along the river. This study discusses the frequency at which meanders along the Ucayali River shift from low sinuosity to complete maturity in order to produce cutoffs.

Analysing the meandering rivers responses to the slope-changes, depending on their bankfull discharge - Case study in the Pannonian Basin

NASA Astrophysics Data System (ADS)

Petrovszki, Judit; Timár, Gábor; Molnár, Gábor

2014-05-01

The multi-variable connection between the channel slope, bankfull discharge and sinuosity values were analysed to get a mathematical formula, which describes the responses of the rivers, and gives the probable sinuosity values for every slope and discharge values. Timár (2003) merged two planar diagrams into a quasi 3D graph. One of them displayed how the river pattern changes, according to the slope and bankfull discharge values (Leopold and Wolmann, 1957; Ackers and Charlton, 1971); the other based on flume experiments, and gives a connection between the slope and sinuosity (Schumm and Khan, 1972). The result graph suggests that the slope-sinuosity connection also works along the natural rivers, for every discharge values. The aim of this work was to prove this relation, and describe it numerically. The sinuosity values were calculated along the natural, meandering river beds, using historical maps (2nd Military Survey of the Habsburg Empire, from the 19th century). The available slope and discharge values were imported from a database measured after the main river control works, at the beginning of the 20th century (Viczián, 1905). Analysing the reports of the river control works, the natural slope could be computed for every river sections. The mean discharges were also converted to bankfull discharges. Neither long time series, nor cross sectional areas were obtainable, so other method was used to generate the bankfull discharge. After the above mentioned corrections a quadratic polynomial surface was fitted onto these points with least squares regression. The cross section of this surface follows the theoretical slope-sinuosity graph, verifying that the flume experiments and natural rivers behave similarly. The differences between the fitted surface and the original points were caused by other river parameters, which also affect the natural rivers (e.g. the sediment discharge). Furthermore, this graph confirms the connection between the slope and sinuosity

Flow Structure and Channel Morphology at a Confluent-Meander Bend

NASA Astrophysics Data System (ADS)

Riley, J. D.; Rhoads, B. L.

2009-12-01

Flow structure and channel morphology in meander bends have been well documented. Channel curvature subjects flow through a bend to centrifugal acceleration, inducing a counterbalancing pressure-gradient force that initiates secondary circulation. Transverse variations in boundary shear stress and bedload transport parallel cross-stream movement of high velocity flow and determine spatial patterns of erosion along the outer bank and deposition along the inner bank. Laboratory experiments and numerical modeling of confluent-meander bends, a junction planform that develops when a tributary joins a meandering river along the outer bank of a bend, suggest that flow and channel morphology in such bends deviate from typical patterns. The purpose of this study is to examine three-dimensional (3-D) flow structure and channel morphology at a natural confluent-meander bend. Field data were collected in southeastern Illinois where Big Muddy Creek joins the Little Wabash River near a local maximum of curvature along an elongated meander loop. Measurements of 3-D velocity components were obtained with an acoustic Doppler current profiler (ADCP) for two flow events with differing momentum ratios. Channel bathymetry was also resolved from the four-beam depths of the ADCP. Analysis of velocity data reveals a distinct shear layer flanked by dual helical cells within the bend immediately downstream of the confluence. Flow from the tributary confines flow from the main channel along the inner part of the channel cross section, displacing the thalweg inward, limiting the downstream extent of the point bar, protecting the outer bank from erosion and enabling bar-building along this bank. Overall, this pattern of flow and channel morphology is quite different from typical patterns in meander bends, but is consistent with a conceptual model derived from laboratory experiments and numerical modeling.

Hyporheic Exchange Flows and Biogeochemical Patterns near a Meandering Stream: East Fork of the Jemez River, Valles Caldera National Preserve, New Mexico

NASA Astrophysics Data System (ADS)

Christensen, H.; Wooten, J. P.; Swanson, E.; Senison, J. J.; Myers, K. D.; Befus, K. M.; Warden, J.; Zamora, P. B.; Gomez, J. D.; Wilson, J. L.; Groffman, A.; Rearick, M. S.; Cardenas, M. B.

2012-12-01

A study by the 2012 Hydrogeology Field Methods class of the University of Texas at Austin implemented multiple approaches to evaluate and characterize local hyporheic zone flow and biogeochemical trends in a highly meandering reach of the of the East Fork of the Jemez River, a fourth order stream in northwestern New Mexico. This section of the Jemez River is strongly meandering and exhibits distinct riffle-pool morphology. The high stream sinuosity creates inter-meander hyporheic flow that is also largely influenced by local groundwater gradients. In this study, dozens of piezometers were used to map the water table and flow vectors were then calculated. Surface water and ground water samples were collected and preserved for later geochemical analysis by ICPMS and HPLC, and unstable parameters and alkalinity were measured on-site. Additionally, information was collected from thermal monitoring of the streambed, stream gauging, and from a series of electrical resistivity surveys forming a network across the site. Hyporheic flow paths are suggested by alternating gaining and losing sections of the stream as determined by stream gauging at multiple locations along the reach. Water table maps and calculated fluxes across the sediment-water interface also indicate hyporheic flow paths. We find variability in the distribution of biogeochemical constituents (oxidation-reduction potential, nitrate, ammonium, and phosphate) along interpreted flow paths which is partly consistent with hyporheic exchange. The variability and heterogeneity of reducing and oxidizing conditions is interpreted to be a result of groundwater-surface water interaction. Two-dimensional mapping of biogeochemical parameters show redox transitions along interpreted flow paths. Further analysis of various measured unstable chemical parameters results in observable trends strongly delineated along these preferential flow paths that are consistent with the direction of groundwater flow and the assumed

Modeling the stratigraphy and preservation potential of meandering stream deposits

NASA Astrophysics Data System (ADS)

Tucker, G. E.; Clevis, Q.; Lock, G.; Lancaster, S.; Desitter, A.

2003-12-01

Both natural and human-induced modes of river and floodplain behavior have the potential to obscure, expose, or even destroy portions of the archaeological record. In valley systems with actively meandering channels much material can be lost to lateral bank erosion. Conversely, floodplain aggradation can bury and therefore obscure sites. In this study we aim to quantify the preservation potential of fluvial units containing archaeological sites as a function of the natural process of meandering, climate change and increased land-use during the Holocene. We used the CHILD simulation model of landscape evolution to explore alternative scenarios in which these three factors are both varied independently and combined. Boundary and initial conditions for the model scenarios are based on the Holocene evolution of the archaeologically-rich Upper Thames Valley, which is known to have witnessed variations in flood frequency, land-clearance, episodic alluviation and river entrenchment. The CHILD model is set up to combine four components that simulate the development of valley and floodplain system: hillslope and channel erosion, lateral stream meandering, overbank deposition, and the accumulation of a 3D stratigraphy. The landscape is represented by an adaptable triangular mesh of nodes, especially suited for simulating the gradual shifting of meander bends. The new stratigraphic layering routine recently added to the model in improves the resolution of the stratigraphic record accumulated by the model. Simulation results reveal systematic controls on preservation potential, and suggest potential sources of bias in the archaeological record.

Three-dimensional flow structure and patterns of bed shear stress in an evolving compound meander bend

USGS Publications Warehouse

Engel, Frank; Rhoads, Bruce L.

2016-01-01

Compound meander bends with multiple lobes of maximum curvature are common in actively evolving lowland rivers. Interaction among spatial patterns of mean flow, turbulence, bed morphology, bank failures and channel migration in compound bends is poorly understood. In this paper, acoustic Doppler current profiler (ADCP) measurements of the three-dimensional (3D) flow velocities in a compound bend are examined to evaluate the influence of channel curvature and hydrologic variability on the structure of flow within the bend. Flow structure at various flow stages is related to changes in bed morphology over the study timeframe. Increases in local curvature within the upstream lobe of the bend reduce outer bank velocities at morphologically significant flows, creating a region that protects the bank from high momentum flow and high bed shear stresses. The dimensionless radius of curvature in the upstream lobe is one-third less than that of the downstream lobe, with average bank erosion rates less than half of the erosion rates for the downstream lobe. Higher bank erosion rates within the downstream lobe correspond to the shift in a core of high velocity and bed shear stresses toward the outer bank as flow moves through the two lobes. These erosion patterns provide a mechanism for continued migration of the downstream lobe in the near future. Bed material size distributions within the bend correspond to spatial patterns of bed shear stress magnitudes, indicating that bed material sorting within the bend is governed by bed shear stress. Results suggest that patterns of flow, sediment entrainment, and planform evolution in compound meander bends are more complex than in simple meander bends. Moreover, interactions among local influences on the flow, such as woody debris, local topographic steering, and locally high curvature, tend to cause compound bends to evolve toward increasing planform complexity over time rather than stable configurations.

A Conceptual Model of Riparian Forest Response to Channel Abandonment on Meandering Rivers

NASA Astrophysics Data System (ADS)

Stella, J. C.; Hayden, M. K.; Battles, J. J.; Piegay, H.; Dufour, S.; Fremier, A. K.

2008-12-01

On alluvial rivers, hydrogeomorphic regimes exert a primary control on the regeneration of pioneer riparian forest stands and thus their composition and age structure. Seasonal flow patterns provide the necessary conditions for recruitment, and channel migration drives patterns of forest stand dynamics. To date, studies of pioneer riparian forest structure have focused primarily on point bar habitats, where woody vegetation typically recruits with decadal frequency in even-aged bands parallel to the river margin. However, there are indications that other recruitment pathways exist and can be important from a population and conservation perspective. On floodplains where channel migration occurs as infrequent cutoff or avulsion events, the geometry and position of the old channel relative to the new one determines rates and patterns of sedimentation and flood frequency. These conditions provide a brief opportunity for forest recruitment, and geomorphic evolution of the former channel habitat in turn influences forest dynamics. The population implications of this alternative forest regeneration pathway depend on the temporal dynamics of channel abandonment versus the rate of lateral channel migration. Preliminary analysis indicates that the geographic scope of this ecogeomorphological process is sizable. Along the Sacramento River (CA) and Ain River (France), for example, cottonwood-dominated stands associated with abandoned channels tend to be less frequent in number (38% of all stands) but larger in area (accounting for 53% of all forest area) relative to forest stands associated with laterally migrating point bars. Dendrochronological analysis confirms that tree ages in floodplain stands corresponds to the first decade after channel abandonment. These data indicate that changes to the rate and scale of channel abandonment due to human and climatic alterations to the flow regime will likely influence riparian corridor-wide tree population structure and forest

Enhanced sediment loading facilitates point bar growth and accelerates bank erosion along a modelled meander bend on the Sacramento River, USA

NASA Astrophysics Data System (ADS)

Ahmed, J.; Constantine, J. A.; Hales, T. C.

2017-12-01

Meandering channels provide a conduit through which sediment and water is routed from the uplands to the sea. Alluvial material is periodically stored and transported through the channel network as permitted by the prevailing hydrologic conditions. The lowlands are typically characterised by accumulations of sediment attached to the inner banks of meander bends (point bars). These bedforms have been identified as important for facilitating a link between in-stream sediment supplies and channel dynamism. A 2D curvilinear hydrodynamic model (MIKE 21C) was used to perform a number of experiments in which the sediment load was adjusted to investigate how changes in alluvial material fluxes affect the development of point bars and the resultant patterns of bank erosion. A doubling of the sediment load caused a longitudinal increase in the bar in the upstream direction and caused a coeval doubling of the transverse channel slope at the meander apex. The upstream growth of the point bar was accompanied by an increase in length over which lateral migration took place at the outer bank. The magnitude of outer bank erosion was 9-times greater for the high-sediment simulation. These results suggest that enhanced sediment loads (potentially the result of changes in land use or climate) can trigger greater rates of bank erosion and channel change through the sequestration of alluvial material on point bars, which encourage high-velocity fluid deflection towards the outer bank of the meander. This controls riparian habitat development and exchanges of sediment and nutrients across the channel-floodplain interface.

Transposition of a Process-Based Model, Flumy: from Meandering Fluvial Systems to Channelized Turbidite Systems

NASA Astrophysics Data System (ADS)

Lemay, M.; Cojan, I.; Rivoirard, J.; Grimaud, J. L.; Ors, F.

2017-12-01

Channelized turbidite systems are among the most important hydrocarbon reservoirs. Yet building realistic turbidite reservoir models is still a challenge. Flumy has been firstly developed to simulate the long-term evolution of aggrading meandering fluvial systems in order to build facies reservoir models. In this study, Flumy has been transposed to channelized turbidite systems. The channel migration linear model of Imran et al. (1999) dedicated to subaqueous flows has been implemented. The whole model has been calibrated taking into account the differences on channel morphology, avulsion frequency, and aggradation and migration rates. This calibration and the comparison of the model to natural systems rely on: i) the channel planform morphology characterized by the meander wavelength, amplitude, and sinuosity; ii) the channel trajectory and the resulting stratigraphic architecture described using Jobe et al. (2016) indexes. Flumy succeeds in reproducing turbidite channel planform morphology as shown by the mean sinuosity of 1.7, the wavelength to width and amplitude to width ratios around 4 and 1 respectively. First-order meander architecture, characterized by the ratios meander belt width versus channel width, meander belt thickness versus channel depth, and the deduced stratigraphic mobility number (the ratio between lateral versus vertical channel displacements), is also well reproduced: 2.5, 3.8, and 0.6 respectively. Both lateral and downstream channel normalized migrations are around 3.5 times lower than in fluvial systems. All these values are absolutely coherent with the observations. In the other hand, the channel trajectory observed on seismic cross sections (hockey stick geometry) is not fully reproduced: the local stratigraphic mobility number is divided upward by 3 whereas up to 10 is expected. This behavior is generally explained in the literature by an increasing aggradation rate through time and/or flow stripping at outer bend that decreases

Numerical modeling of dune progression in a high amplitude meandering channel

USDA-ARS?s Scientific Manuscript database

Laboratory experiments carried out by Abad and Garcia (2009) in a high-amplitude Kinoshita meandering channel show bed morphodynamics to comprise steady (local scour and deposition) and unsteady (migrating bedforms) components. The experiments are replicated with a numerical model. The sediment tran...

Timescale bias in measuring river migration rate

NASA Astrophysics Data System (ADS)

Donovan, M.; Belmont, P.; Notebaert, B.

2016-12-01

River channel migration plays an important role in sediment routing, water quality, riverine ecology, and infrastructure risk assessment. Migration rates may change in time and space due to systematic changes in hydrology, sediment supply, vegetation, and/or human land and water management actions. The ability to make detailed measurements of lateral migration over a wide range of temporal and spatial scales has been enhanced from increased availability of historical landscape-scale aerial photography and high-resolution topography (HRT). Despite a surge in the use of historical and contemporary aerial photograph sequences in conjunction with evolving methods to analyze such data for channel change, we found no research considering the biases that may be introduced as a function of the temporal scales of measurement. Unsteady processes (e.g.; sedimentation, channel migration, width changes) exhibit extreme discontinuities over time and space, resulting in distortion when measurements are averaged over longer temporal scales, referred to as `Sadler effects' (Sadler, 1981; Gardner et al., 1987). Using 12 sets of aerial photographs for the Root River (Minnesota), we measure lateral migration over space (110 km) and time (1937-2013) assess whether bias arises from different measurement scales and whether rates shift systematically with increased discharge over time. Results indicate that measurement-scale biases indeed arise from the time elapsed between measurements. We parsed the study reach into three distinct reaches and examine if/how recent increases in river discharge translate into changes in migration rate.

Hydrodynamics and Connectivity of Channelized Floodplains: Insights from the Meandering East Fork White River, Indiana, USA

NASA Astrophysics Data System (ADS)

Czuba, J. A.; David, S. R.; Edmonds, D. A.

2017-12-01

High resolution topography reveals that meandering river floodplains in Indiana commonly have networks of channels. These floodplain channel networks are most prevalent in agricultural, low-gradient, wide floodplains. It appears that these networks are formed when floodplain channels connect oxbows to each other and the main river channel. Collectively, the channels in the floodplain create an interconnected network of pathways that convey water beginning at flows less than bankfull, and as stage increases, more of the floodplain becomes dissected by floodplain channels. In this work, we quantify the hydrodynamics and connectivity of the flow on the floodplain and in the main channel of the East Fork White River near Seymour, Indiana, USA. We constructed a two-dimensional numerical model using HECRAS of the river-floodplain system from LiDAR data and from main-channel river bathymetry to elucidate the behaviour of these floodplain channels across a range of flows. Model calibration and verification data included stage from a USGS gage, high-water marks at a high and medium flow, and an aerial photograph of inundation in the floodplain channels. The numerical model simulated flow depth and velocity, which was used to quantify connectivity of the floodplain channels, exchange between the main channel and floodplain channels, and residence time of water on the floodplain. Model simulations suggest that the floodplain channels convey roughly 50% of the total flow at what is typically considered "bankfull" flow. Overall, we present a process-based approach for analyzing complex floodplain-river systems where an individual floodplain-river system can be distilled down to a set of characteristic curves. Notably, we map the East Fork White River system to exchange-residence time space and argue that this characterization forms the basis for thinking about morphologic evolution (e.g., sediment deposition and erosion) and biogeochemistry (e.g., nitrate removal) in floodplain-river

Exploring Controls on Sinuousity, Terraces and River Capture in the Upper Dajia River, Taiwan

NASA Astrophysics Data System (ADS)

Belliveau, L. C.; Ouimet, W. B.; Chan, Y. C.; Byrne, T. B.

2015-12-01

Taiwan is one of the most tectonically active regions in the world and is prone to landslides due to steep topography, large earthquakes and frequent typhoons. Landslides often affect and alter the river valleys beneath them, producing knickpoints on longitudinal river profiles, segmenting valleys into mixed bedrock-alluvial rivers and affecting river incision for tens to thousands of years. This study investigates the origin and evolution of complex channel morphologies, terraces and river capture along a 20km stretch of the Upper Da-Jia River in the Heping area of Taiwan. Through GIS analysis and field studies, we explore controls on river channel sinuousity, terrace development and river capture in relation to tectonic and climatic forcing, rock erodibility and landslides. High channel sinuousity is proposed as the result of a coupling between bank erosion and landslides. We discuss three types of landslide-induced meanders and increased sinuousity: (a) depositional-push meanders, (b) failure-zone erosional meanders, and (c) complex-erosional meanders. We also investigate spatial variation in channel morphology (slope, width) and the distribution and heights of river terraces within the Upper Da-Jia watershed associated with periods of widespread valley filling from landslide activity. Examples of river capture provide further evidence of the dynamic interactions between river incision, landslides and associated changes in channel morphology and terrace development within steep rapidly uplift, eroding and evolving mountain belts.

The storage time, age, and erosion hazard of laterally accreted sediment on the floodplain of a simulated meandering river

USGS Publications Warehouse

Bradley, D. Nathan; Tucker, Gregory E.

2013-01-01

A sediment particle traversing the fluvial system may spend the majority of the total transit time at rest, stored in various sedimentary deposits. Floodplains are among the most important of these deposits, with the potential to store large amounts of sediment for long periods of time. The virtual velocity of a sediment grain depends strongly on the amount of time spent in storage, but little is known about sediment storage times. Measurements of floodplain vegetation age have suggested that storage times are exponentially distributed, a case that arises when all the sediment on a floodplain is equally vulnerable to erosion in a given interval. This assumption has been incorporated into sediment routing models, despite some evidence that younger sediment is more likely to be eroded from floodplains than older sediment. We investigate the relationship between sediment age and erosion, which we term the “erosion hazard,” with a model of a meandering river that constructs its floodplain by lateral accretion. We find that the erosion hazard decreases with sediment age, leading to a storage time distribution that is not exponential. We propose an alternate model that requires that channel motion is approximately diffusive and results in a heavy tailed distribution of storage time. The model applies to timescales over which the direction of channel motion is uncorrelated. We speculate that the lower end of this range of time is set by the meander cutoff timescale and the upper end is set by processes that limit the width of the meander belt.

Late Quaternary river channel migrations of the Kura River in Transcaucasia - tectonic versus climatic causes

NASA Astrophysics Data System (ADS)

von Suchodoletz, Hans; Gärtner, Andreas; Hoth, Silvan; Umlauft, Josefine; Godoladze, Tea; Faust, Dominik

2015-04-01

Large-scale river channel migrations either in the form of avulsions or combing, i.e. progressive lateral migrations, are global phenomena during the Late Quaternary. Such channel migrations were triggered by tectonics, climate change, human activity or a combination of those factors. River channel migrations have the potential to cause significant human and economic losses. Thus, a more thorough knowledge about underlying causes and process rates is essential. Furthermore, such studies will elucidate the sensitivity or robustness of rivers to different external and internal forcing-agents, i.e. they help to identify the dominant drivers of regional landscape evolution. The Caucasus region is part of the active collision zone between the Africa-Arabian and the Eurasian plates, and is characterized by high current tectonic activity. Furthermore, significant environmental changes took place during the Late Quaternary, i.e. the shrinking or even disappearance of glaciers in the Greater and Lesser Caucasus or fundamental changes of the vegetation cover varying between woodland and grassland-dominated vegetation. The Kura River is the main gaining stream of the Transcaucasian Depression located between the Greater Caucasus Mountains in the north and the Lesser Caucasus Mountains in the south, and receives several tributaries from both mountain ranges. This study focusses on the middle course of the Kura River in eastern Georgia, SE of the city of Tbilisi. Integration of fluvial geomorphology, geochronology, heavy mineral analyses and seismo-tectonic analyses demonstrates that this part of the Kura River underwent large-scale channel migrations up to >10 km during Late Pleistocene and Holocene. It is interpreted that these movements followed both tectonic and climatic triggers: Whereas SW-ward migrations were caused by tectonic uplift in and SW-directed advance of the Kura fold and thrust belt as part of the Greater Caucasus, NE-ward migrations occurred during cold

Optimum Pathways of Fish Spawning Migrations in Rivers

NASA Astrophysics Data System (ADS)

McElroy, B. J.; Jacobson, R. B.; Delonay, A.

2010-12-01

Many fish species migrate large distances upstream in rivers to spawn. These migrations require energetic expenditures that are inversely related to fecundity of spawners. Here we present the theory necessary to quantify relative energetic requirements of upstream migration pathways and then test the hypothesis that least-cost paths are taken by the federally endangered pallid sturgeon (Scaphyrhyncus Albus), a benthic rheophile, in the lower Missouri River, USA. Total work done by a fish through a migratory path is proportional to the size of the fish, the total drag on the fish, and the distance traversed. Normalizing by the work required to remain stationary at the beginning of a path, relative work expenditure at each point of the path is found to be the cube of the ratio of the velocity along the path to the velocity at the start of the path. This is the velocity of the fish relative to the river flow. A least-cost migratory pathway can be determined from the velocity field in a reach as the path that minimizes a fish's relative work expenditure. We combine location data from pallid sturgeon implanted with telemetric tags and pressure-sensitive data storage tags with depth and velocity data collected with an acoustic Doppler profiler. During spring 2010 individual sturgeon were closely followed as they migrated up the Missouri River to spawn. These show that, within a small margin, pallid sturgeon in the lower Missouri River select least-cost paths as they swim upstream (typical velocities near 1.0 - 1.2 m/s). Within the range of collected data, it is also seen that many alternative paths not selected for migration are two orders of magnitude more energetically expensive (typical velocities near 2.0 - 2.5 m/s). In general these sturgeon migrated along the inner banks of bends avoiding high velocities in the thalweg, crossing the channel where the thalweg crosses in the opposite direction in order to proceed up the inner bank of subsequent bends. Overall, these

Influences of Relative Sea-Level Rise and Mississippi River Delta Plain Evolution on the Holocene Middle Amite River, Southeastern Louisiana

USGS Publications Warehouse

Autin, W.J.

1993-01-01

The Holocene geomorphic history of southeastern Louisiana's middle Amite River is recorded in the stratigraphy of three alloformations, identified in decreasing age as the Watson (WAT), Denham Springs (DS), and Magnolia Bridge (MAG). The WAT meander belt formed by at least 9000 yr B.P., when sea level was lower and the Amite River was tributary to a larger ancestral drainage basin. The DS became an active meander belt by at least 3000 yr B.P., in response to relative sea-level rise and eastward progradation of the Mississippi River delta plain. The MAG developed its meander belt, in part, during the European settlement of the drainage basin, and is now attempting to adjust to modern anthropogenic influences. Geomorphic influences on the middle Amite River floodplain have temporal and spatial components that induce regional- and local-scale effects. Regional extrinsic influences caused meander belt avulsion that produced alloformations. However, local influences produced intrinsic geomorphic thresholds that modified channel morphology within a meander belt but did not induce alloformation development. Base-level influences of the relative sea-level rise and the Mississippi River delta plain were so dominant that the effects of possible climate change were not recognized in the Holocene Amite River system.

Out of Africa: the importance of rivers as human migration corridors

NASA Astrophysics Data System (ADS)

Ramirez, J. A.; Coulthard, T. J.; Rogerson, M.; Barton, N.; Bruecher, T.

2013-12-01

The route and timing of Homo sapiens exiting Africa remains uncertain. Corridors leading out of Africa through the Sahara, the Nile Valley, and the Red Sea coast have been proposed as migration routes for anatomically modern humans 80,000-130,000 years ago. During this time climate conditions in the Sahara were wetter than present day, and monsoon rainfall fed rivers that flowed across the desert landscape. The location and timing of these rivers may have supported human migration northward from central Africa to the Mediterranean coast, and onwards to Europe or Asia. Here, we use palaeoclimate rainfall and a hydrological model to spatially simulate and quantitatively test the existence of three major rivers crossing the Sahara from south to north during the time of human migration. We provide evidence that, given realistic underlying climatology, the well-known Sahabi and Kufrah rivers very likely flowed across modern day Libya and reached the coast. More unexpectedly an additional river crossed the core of the Sahara through Algeria (Irharhar river) and flowed into the Chotts basin. The Irharhar river is unique, because it links locations in central Africa experiencing monsoon climates with temperate coastal Mediterranean environments where food and resources were likely abundant. From an ecological perspective, this little-known corridor may prove to be the most parsimonious migration route. Support for the Irharar as a viable migration corridor is provided by its geographic proximity to middle Stone Age archaeological artefacts found in North Africa. Our new, highly novel approach provides the first quantitative analysis of the likelihood that rivers occurred during the critical period of human migration out of Africa. Simulated probability of surface water in North Africa during the last interglacial and the location of tools and ornaments from the Middle Stone Age.

Morphological adjustments in a meandering reach of the middle Yangtze River caused by severe human activities

NASA Astrophysics Data System (ADS)

Zhou, Meirong; Xia, Junqiang; Lu, Jinyou; Deng, Shanshan; Lin, Fenfen

2017-05-01

In the past 50 years, the Shishou reach in the middle Yangtze River underwent significant channel evolution owing to the implementation of an artificial cutoff, the construction of bank revetment works and the operation of the Three Gorges Project (TGP). Based on the measured hydrological data and topographic data, the processes of channel evolution in this reach were investigated mainly from the adjustments in planform and cross-sectional geometries. The variation in planform geometry obtained in this study indicates that (i) the artificial cutoff at Zhongzhouzi caused the river regime to adjust drastically, with the mean rate of thalweg migration at reach scale of 42.0 m/a over the period 1966-1975; (ii) then the effect of this artificial cutoff reduced gradually, with the mean migration rate decreasing to < 30 m/a in 1975-1993, while it increased to > 40 m/a owing to the occurrence of high water levels in 1993-1998; and (iii) the average annual rate of thalweg migration decreased to 29.3 m/a because of the impacts of various bank protection engineering and the TGP operation during the period 2002-2015. However, remarkable thalweg migration processes still occurred in local regions after the TGP operation, which resulted in significant bankline migration in local reaches of Beimenkou, Shijiatai, and Tiaoxiankou. In addition, the adjustments of bankfull channel geometry were investigated at section and reach scales after the TGP operation. Calculated results show that lateral channel migration in this reach was restricted by various river regulation works and that channel evolution was mainly characterized by an increase in bankfull depth and cross-sectional area. Empirical relationships were developed between the reach-scale bankfull dimensions (depth and area), the bankfull widths at specified sections, and the previous 5-year average fluvial erosion intensity during flood seasons, with high correlation degrees between them being obtained.

Impact of meander geometry and stream flow events on residence times and solute transport in the intra-meander flow

NASA Astrophysics Data System (ADS)

Nasir Mahmood, Muhammad; Schmidt, Christian; Trauth, Nico

2017-04-01

Stream morphological features, in combination with hydrological variability play a key role in water and solute exchange across surface and subsurface waters. Meanders are prominent morphological features within stream systems which exhibit unique hydrodynamics. The water surface elevation difference across the inner bank of a meander induces lateral hyporheic exchange within the intra-meander region. This hyporheic flow is characterized by considerably prolonged flow paths and residence times (RT) compared to smaller scales of hyporheic exchange. In this study we examine the impact of different meander geometries on the intra-meander hyporheic flow field and solute mobilization under both steady state and transient flow conditions. We developed a number of artificial meander shape scenarios, representing various meander evolution stages, ranging from a typical initial to advanced stage (near cut off ) meander. Three dimensional steady state numerical groundwater flow simulations including the unsaturated zone were performed for the intra-meander region. The meandering stream was implemented in the model by adjusting the top layers of the modelling domain to the streambed elevation and assigning linearly decreasing head boundary conditions to the streambed cells. Residence times for the intra-meander region were computed by advective particle tracking across the inner bank of meander. Selected steady state cases were extended to transient flow simulations to evaluate the impact of stream discharge events on the temporal behavior of the water exchange and solute transport in the intra-meander region. The transient stream discharge was simulated for a number of discharge events of variable duration and peak height using the surface water model HEC-RAS. Transient hydraulic heads obtained from the surface water model were applied as transient head boundary conditions to the streambed cells of the groundwater model. A solute concentration source was added in the

The performance of the Hydromorphological Index of Diversity (HMID) in a hydropower affected meandering river

NASA Astrophysics Data System (ADS)

Stähly, Severin; Bourqui, Pierre; Franca, Mario J.; Robinson, Christopher; Schleiss, Anton J.

2016-04-01

More than half of the Swiss electricity is produced by hydropower. Large price fluctuations cause severe hydropeaking flow regimes due to corresponding production fluctuations, which undisputedly have a negative impact on aquatic biota. Water diversion due to dams on the other hand imposes downstream residual flow regimes. The absence of flood events and regular sediment supply disrupts sediment dynamics and disconnects floodplains, which are habitats of high value, from its main channel. The residual-flow controlled reach at the Sarine river in western Switzerland is the subject of the present study. The Sarine meanders strongly and the river reach under analysis has a bed incision of locally more than 100 m. Its incision provokes the isolation of the river which is consequently minimally touched by human structures and shows a natural geomorphology. Since the construction of a dam upstream this reach in 1948, aiming at the water abstraction to hydropower, vegetation could establish and the active floodplain decreased its area, as airborne images show. Nevertheless, it is classified as a floodplain of national importance and it has been under protection since 1992. It is supposed to be a valuable habitat for a wide range of organisms. The Hydromorphological Index of Diversity (HMID) is a simple tool for quantifying the habitat richness in a river reach, taking into account the mean values and the variation of water depth and flow velocity. For channelized rivers, HMID values from up to 5 are expected, while morphological pristine sites with a high spatial variability of water depth and velocity show values of 9 or higher. For the residual flow of the Sarine River, flow depth and velocity were measured using ADCP and ADV. The results are compared with a nearby natural reference river and the outcome of a 2D numerical simulation. Finally, the behaviour and limitations of the HMID, in a hydropower affected river, are discussed. In the close future an artificial flood

Dryland anabranching river morphodynamics: Río Capilla, Salar de Uyuni, Bolivia

NASA Astrophysics Data System (ADS)

Li, Jiaguang; Bristow, Charlie S.; Luthi, Stefan M.; Donselaar, Marinus E.

2015-12-01

The dryland anabranching river Río Capilla is characterized by nonvegetated and vegetated reaches with prominent channel morphology. To identify the morphodynamics of such dryland anabranching systems and their controls, we investigated the Río Capilla of the southern Altiplano Plateau using high-resolution satellite imagery and field measurements. Comparison of high-resolution satellite data reveals that erosion exceeds deposition for the main channel, accompanied by changes in channel planform, such as meander and channel morphology. On-site surveys combined with high-precision GPS and high-resolution satellite imagery show that channels are characterized by shallowness and poor development of levees. The study area of the Río Capilla is divided into two zones of different slopes: zone 1 with a high slope and zone 2 with a low slope. Zone 1 has a relatively straight main channel with few anabranches and grass-covered banks that are stable despite the high gradient; whereas zone 2 is typified by more anabranches with nonvegetated banks, and the main channel experiences prominent bank accretion and erosion. Excavations show that point-bar deposits are fine-sand-dominated in two reaches and that river banks primarily consist of silt and clay. The limited vegetation cover and abundance of desiccation cracks and macropores make the river bank more erodible leading to pronounced lateral migration in this low-gradient dryland river system. Shallow channels and poor development of levees in combination with in-channel accretionary benches result in frequent overbank flooding, which results in a high density of crevasse splays over unconsolidated river banks and accretionary benches. Connection of headcuts and crevasse channels together with lateral migration and chute channels and reactivation of partially abandoned meanders produces an anabranching pattern in such dryland river systems.

Investigating historical changes in morphodynamic processes associated with channelization of a large Alpine river: the Etsch/Adige River, NE Italy

NASA Astrophysics Data System (ADS)

Zen, Simone; Scorpio, Vittoria; Mastronunzio, Marco; Proto, Matteo; Zolezzi, Guido; Bertoldi, Walter; Comiti, Francesco; Surian, Nicola; Prà, Elena Dai

2016-04-01

River channel management within the last centuries has largely modified fluvial processes and morphodynamic evolution of most large European rivers. Several river systems experienced extensive channelization early in the 19th century, thus strongly challenging our present ability to detect their morphodynamic functioning with contemporary photogrammetry or cartographical sources. This consequently leaves open questions about their potential future response, especially to management strategies that "give more room" to the river, aiming at partially rehabilitating their natural functioning. The Adige River (Etsch in German), the second longest Italian river, is an exemplary case where channelization occurred more than 150 years ago, and is the focus of the present work. This work aims (i) to explore changes in fundamental morphodynamic processes associated with massive channelization of the Adige River and (ii) to quantify the alteration in river bars characteristics, by using morphodynamic models of bars and meandering. To fulfil our aims we combine the analysis of historical data with morphodynamic mathematical modelling. Historical sources (recovered in a number of European archives), such as hydrotopographical maps, airborne photogrammetry and hydrological datasets were collected to investigate channel morphology before and after the channelization. Information extracted from this analysis was combined with morphodynamic linear models of free migrating and forced steady bars, to investigate river bars and bend stability properties under different hydromorphological scenarios. Moreover, a morphodynamic model for meandering channel was applied to investigate the influence of river channel planform on the evolution of the fluvial bars. Results from the application of morphodynamic models allowed to predict the type, position and geometry of bars characterizing the channelized configuration of the river, and to explain the presently observed relative paucity of bars

Simulation of Helical Flow Hydrodynamics in Meanders and Advection-Turbulent Diffusion Using Smoothed Particle Hydrodynamics

NASA Astrophysics Data System (ADS)

Gusti, T. P.; Hertanti, D. R.; Bahsan, E.; Soeryantono, H.

2013-12-01

Particle-based numerical methods, such as Smoothed Particle Hydrodynamics (SPH), may be able to simulate some hydrodynamic and morphodynamic behaviors better than grid-based numerical methods. This study simulates hydrodynamics in meanders and advection and turbulent diffusion in straight river channels using Microsoft Excel and Visual Basic. The simulators generate three-dimensional data for hydrodynamics and one-dimensional data for advection-turbulent diffusion. Fluid at rest, sloshing, and helical flow are simulated in the river meanders. Spill loading and step loading are done to simulate concentration patterns associated with advection-turbulent diffusion. Results indicate that helical flow is formed due to disturbance in morphology and particle velocity in the stream and the number of particles does not have a significant effect on the pattern of advection-turbulent diffusion concentration.

Misssissippi River and St. Louis, MO

NASA Image and Video Library

1973-06-22

SL2-81-189 (22 June 1973) --- The well defined meanderings of the Mississippi River, just to the south of St. Louis, MO (38.5N, 90.5W) can easily be seen as curved lines and loops roughly paralleling the present river in this view showing the former water channels. The vegetated bluffs on either side of the river define the limits of the meanders where the rich river flood plain offers some of the most fertile land for agriculture although flooding remains a constant threat. Photo credit: NASA

Highly Sinuous Meanders on Mars: Morphology, Hydrology and Terrestrial Analogs (Invited)

NASA Astrophysics Data System (ADS)

Howard, A. D.; Burr, D. M.; Williams, R.

2009-12-01

Of the rare preserved channel features on Mars, perhaps the most exciting are highly sinuous channels found, to date, in only three locations. We discuss the most extensive of these channel systems in the Aeolis/Zephyra Plana region. The channel features stand in positive relief (as inverted channels). The morphological assemblage of the sinuous ridges [Burr et al., 2009] presents a compelling case for their origin through persistent fluvial meandering within branching networks of preserved channels and associated meander belts. High resolution images reveal narrow sinuous ridges which can often be traced over tens of torturous loops. Wavelengths of these sinuous plateaus range from about 200-500 m and the width of the superposed or embedded ridges ranges from about 20-100 m where well preserved. The flat-topped plateaus exhibit irregular outer edges, often with lobate planforms with about the same size and curvature as bends in the associated sinuous ridges. We interpret these to be cutoff meander loops. In some cases parallel lineations occur interior to the sinuous ridges that appear to be analogs to point bar scars in terrestrial meandering channels. We interpret the sinuous ridges and associated sinuous plateaus featuring lobate scarps to be remnants of floodplains and associated channels formed by meandering streams. These have subsequently been eroded into positive relief by aeolian deflation of weaker surrounding deposits. At the time of fluvial activity the valleys would have been surrounded by uplands (probably with low relief). The dendritic pattern of the floodplain deposits and the considerable period of time required to sculpt the wide floodplains through lateral meander migration with cutoffs indicates a water source from distributed precipitation as rain or snow followed by runoff. The primary geomorphic issue with the martian meanders is the mechanism providing bank cohesion and a low aspect ratio. Terrestrial highly sinuous, unconfined meanders

Controls on sinuosity in the sparsely vegetated Fossálar River, southern Iceland

NASA Astrophysics Data System (ADS)

Ielpi, Alessandro

2017-06-01

Vegetation exerts strong controls on fluvial sinuosity, providing bank stability and buffering surface runoff. These controls are manifest in densely vegetated landscapes, whereas sparsely vegetated fluvial systems have been so far overlooked. This study integrates remote sensing and gauging records of the meandering to wandering Fossálar River, a relatively steep-sloped (< 2.5%) Icelandic river featuring well-developed point bars (79%-85% of total active bar surface) despite the lack of thick, arborescent vegetation. Over four decades, fluctuations in the sinuosity index (1.15-1.43) and vegetation cover (63%-83%) are not significantly correlated (r = 0.28, p > 0.05), suggesting that relationships between the two are mediated by intervening variables and uncertain lag times. By comparison, discharge regime and fluvial planform show direct correlation over monthly to yearly time scales, with stable discharge stages accompanying the accretion of meander bends and peak floods related to destructive point-bar reworking. Rapid planform change is aided by the unconsolidated nature of unrooted alluvial banks, with recorded rates of lateral channel-belt migration averaging 18 m/yr. Valley confinement and channel mobility also control the geometry and evolution of individual point bars, with the highest degree of spatial geomorphic variability recorded in low-gradient stretches where lateral migration is unimpeded. Point bars in the Fossálar River display morphometric values comparable to those of other sparsely vegetated rivers, suggesting shared scalar properties. This conjecture prompts the need for more sophisticated integrations between remote sensing and gauging records on modern rivers lacking widespread plant life. While a large volume of experimental and field-based work maintains that thick vegetation has a critical role in limiting braiding, thus favouring sinuosity, this study demonstrates the stronger controls of discharge regime and alluvial morphology on

Optimum swimming pathways of fish spawning migrations in rivers

USGS Publications Warehouse

McElroy, Brandon; DeLonay, Aaron; Jacobson, Robert

2012-01-01

Fishes that swim upstream in rivers to spawn must navigate complex fluvial velocity fields to arrive at their ultimate locations. One hypothesis with substantial implications is that fish traverse pathways that minimize their energy expenditure during migration. Here we present the methodological and theoretical developments necessary to test this and similar hypotheses. First, a cost function is derived for upstream migration that relates work done by a fish to swimming drag. The energetic cost scales with the cube of a fish's relative velocity integrated along its path. By normalizing to the energy requirements of holding a position in the slowest waters at the path's origin, a cost function is derived that depends only on the physical environment and not on specifics of individual fish. Then, as an example, we demonstrate the analysis of a migration pathway of a telemetrically tracked pallid sturgeon (Scaphirhynchus albus) in the Missouri River (USA). The actual pathway cost is lower than 105 random paths through the surveyed reach and is consistent with the optimization hypothesis. The implication—subject to more extensive validation—is that reproductive success in managed rivers could be increased through manipulation of reservoir releases or channel morphology to increase abundance of lower-cost migration pathways.

The dynamics of an experimental gravel bed meander with constant discharge and sediment supply

NASA Astrophysics Data System (ADS)

Braudrick, C. A.; Dietrich, W.; Sklar, L. S.

2012-12-01

As rivers meander, channel migration and cutoffs introduce continuous and episodic changes, respectively, in local boundary shear stress and bedload flux. These changes must affect the local and reach scale channel dynamics, but assessing their influence is limited by complications associated with varying discharge as well as challenging spatial and time scales. Here we explore the dynamics of a scaled-down gravel bed meandering river with constant discharge and sediment supply in a 6.1 m by 17 m long experimental flume at UC Berkeley's Richmond Field Station. The experiments are similar to Braudrick et al. (2009), but with constant rather than varying sediment supply. The flume was filled with a sorted sand with D50 of 0.85 mm, and had an initial 40 cm wide channel with a sinuosity of 1.1. Alfalfa sprouts provided bank and floodplain strength. The alfalfa was seeded by hand throughout the floodplain while a low flow provided irrigation during the 7-day alfalfa growth period. Sand (model gravel) and a lightweight plastic sediment (model sand) were fed independently from the upstream end of the flume at constant rates of 1.8 and 5 kg/hr, respectively. Despite the steady input conditions the experimental channel was quite dynamic as channel migration and bend morphology varied spatially and temporally. The sinuosity in the downstream 10 m of the flume (away from the inlet condition) increased from 1.1 to about 1.6 over the first 75 hours of the experiment, when 3 cutoffs in 29 hours decreased the sinuosity back to just over the initial value. Bank erosion was fastest when curvature was low at the beginning of the experiment and following cutoffs, and slowed once sinuosity increased. Once curvature increased the bends became asymmetric as bank erosion occurred almost exclusively at the bend apex. As the channel migrated, the local sinuosity increased, which decreasing the water surface slope and hence shear stress. The lower shear stress caused subsequent channel

Relationship Between Vortex Meander and Ambient Turbulence

NASA Technical Reports Server (NTRS)

Rossow, Vernon J.; Hardy, Gordon H.; Meyn, Larry A.

2006-01-01

Efforts are currently underway to increase the capacity of airports by use of closely-spaced parallel runways. If such an objective is to be achieved safely and efficiently during both visual and instrument flight conditions, it will be necessary to develop more precise methods for the prediction of the motion and spread of the hazard posed by the lift-generated vortex-wakes of aircraft, and their uncertainties. The purpose of the present study is to relate the motion induced in vortex filaments by turbulence in the ambient flow field to the measured turbulence in the flow field. The problem came about when observations made in the two largest NASA wind tunnels indicated that extended exposure of vortex wakes to the turbulence in the wind tunnel air stream causes the centers of the vortices to meander about with time at a given downstream station where wake measurements are being made. Although such a behavior was expected, the turbulence level based on the maximum amplitude of meander was much less than the root-mean-squared value measured in the free-stream of the wind tunnel by use of hot-film anemometers. An analysis of the time-dependent motion of segments of vortex filaments as they interact with an eddy, indicates that the inertia of the filaments retards their motion enough in the early part of their travel to account for a large part of the difference in the two determinations of turbulence level. Migration of vortex filaments from one turbulent eddy to another (probably with a different orientation), is believed to account for the remainder of the difference. Methods that may possibly be developed for use in the measurement of the magnitude of the more intense eddies in turbulent flow fields and how they should be adjusted to predict vortex meander are then discussed.

Imaging and locating paleo-channels using geophysical data from meandering system of the Mun River, Khorat Plateau, Northeastern Thailand

NASA Astrophysics Data System (ADS)

Nimnate, P.; Thitimakorn, T.; Choowong, M.; Hisada, K.

2017-12-01

The Khorat Plateau from northeast Thailand, the upstream part of the Mun River flows through clastic sedimentary rocks. A massive amount of sand was transported. We aimed to understand the evolution of fluvial system and to discuss the advantages of two shallow geophysical methods for describing subsurface morphology of modern and paleo-channels. We applied Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) to characterize the lateral, vertical morphological and sedimentary structures of paleo-channels, floodplain and recent point bars. Both methods were interpreted together with on-sites boreholes to describe the physical properties of subsurface sediments. As a result, we concluded that four radar reflection patterns including reflection free, shingled, inclined and hummocky reflections were appropriated to apply as criteria to characterize lateral accretion, the meandering rivers with channel-filled sequence and floodplain were detected from ERT profiles. The changes in resistivity correspond well with differences in particle size and show relationship with ERT lithological classes. Clay, silt, sand, loam and bedrock were classified by the resistivity data. Geometry of paleo-channel embayment and lithological differences can be detected by ERT, whereas GPR provides detail subsurface facies for describing point bar sand deposit better than ERT.

Spatio-Temporal Migration Patterns of Pacific Salmon Smolts in Rivers and Coastal Marine Waters

PubMed Central

Melnychuk, Michael C.; Welch, David W.; Walters, Carl J.

2010-01-01

Background Migrations allow animals to find food resources, rearing habitats, or mates, but often impose considerable predation risk. Several behavioural strategies may reduce this risk, including faster travel speed and taking routes with shorter total distance. Descriptions of the natural range of variation in migration strategies among individuals and populations is necessary before the ecological consequences of such variation can be established. Methodology/Principal Findings Movements of tagged juvenile coho, steelhead, sockeye, and Chinook salmon were quantified using a large-scale acoustic tracking array in southern British Columbia, Canada. Smolts from 13 watersheds (49 watershed/species/year combinations) were tagged between 2004–2008 and combined into a mixed-effects model analysis of travel speed. During the downstream migration, steelhead were slower on average than other species, possibly related to freshwater residualization. During the migration through the Strait of Georgia, coho were slower than steelhead and sockeye, likely related to some degree of inshore summer residency. Hatchery-reared smolts were slower than wild smolts during the downstream migration, but after ocean entry, average speeds were similar. In small rivers, downstream travel speed increased with body length, but in the larger Fraser River and during the coastal migration, average speed was independent of body length. Smolts leaving rivers located towards the northern end of the Strait of Georgia ecosystem migrated strictly northwards after ocean entry, but those from rivers towards the southern end displayed split-route migration patterns within populations, with some moving southward. Conclusions/Significance Our results reveal a tremendous diversity of behavioural migration strategies used by juvenile salmon, across species, rearing histories, and habitats, as well as within individual populations. During the downstream migration, factors that had strong effects on travel

Were Rivers Flowing across the Sahara During the Last Interglacial? Implications for Human Migration through Africa

PubMed Central

Coulthard, Tom J.; Ramirez, Jorge A.; Barton, Nick; Rogerson, Mike; Brücher, Tim

2013-01-01

Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times. PMID:24040347

River capture controlling changes in the drainage pattern and river slope

NASA Astrophysics Data System (ADS)

Castelltort, Xavier; Colombo, Ferran

2016-04-01

The crystalline block of Les Guilleries, in the northeast of the Iberian Peninsula, is part of the Hercynian basement over which Palaeogene materials of the Ebro basinwere deposited . This massif is affected by a family of basement fractures of NW-SE direction which continue under the Paleogene cover. This is evident in the areas of contact between the two units. One of these areas affected by fractures was used by the primitive river Ter to transition, through a process of river capture, from the crystal unit Guilleries, with a rectangular drainage pattern, toward the sedimentary cover of the Ebro basin, with a meander drainage pattern. The fractured material that the river Ter used to deepen against the dip of the layers is more evident due to it being rigid and resistant to erosion, the Sandstones of Folgueroles Fm. The use of fractures resulted in a course of the river Ter that can be divided into three subparallel reaches with a shape of Z, which can be described as structural pseudomeanders. The change in the drainage pattern of the river between its passage accross the basement and the cover can never be the product of a process of antecedence or superimposition as has been proclaimed earlier. The rectangular pattern fits the structure of the crystalline massif. The meandering pattern on the cover is due to the difficulty of flowing through the Sandstones of Folgueroles Fm, and to the subsequent pressure loss affecting the current of the river that moves upstream beyond the Bellmunt Anticline. Up to the point where the pattern meander is conserved, river slope is below 1%. Upstream, the river slope increases significantly due to the adaptation of the river to a new layout.

Temporal patterns of migration and spawning of river herring in coastal Massachusetts

USGS Publications Warehouse

Rosset, Julianne; Roy, Allison; Gahagan, Benjamin I.; Whiteley, Andrew R.; Armstrong, Michael P.; Sheppard, John J.; Jordaan, Adrian

2017-01-01

Migrations of springtime Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis, collectively referred to as river herring, are monitored in many rivers along the Atlantic coast to estimate population sizes. While these estimates give an indication of annual differences in the number of returning adults, links to the subsequent timing and duration of spawning and freshwater juvenile productivity remain equivocal. In this study, we captured juvenile river herring at night in 20 coastal Massachusetts lakes using a purse seine and extracted otoliths to derive daily fish ages and back-calculate spawn dates. Estimates of spawning dates were compared with fishway counts of migrating adults to assess differences in migration timing and the timing and duration of spawning. We observed a distinct delay between the beginning of the adult migration run and the start of spawning, ranging from 7 to 28 d across the 20 lakes. Spawning continued 13–48 d after adults stopped migrating into freshwater, further demonstrating a pronounced delay in spawning following migration. Across the study sites the duration of spawning (43–76 d) was longer but not related to the duration of migration (29–66 d). The extended spawning period is consistent with recent studies suggesting that Alewives are indeterminate spawners. The long duration in freshwater provides the opportunity for top-down (i.e., predation on zooplankton) and bottom-up (i.e., food for avian, fish, and other predators) effects, with implications for freshwater food webs and nutrient cycling. General patterns of spawn timing and duration can be incorporated into population models and used to estimate temporal changes in productivity associated with variable timing and density of spawning river herring in lakes.

Power law time dependence of river flood decay and its relationship to long term discharge frequency distribution. [California

NASA Technical Reports Server (NTRS)

Schubert, G.; Lingenfelter, R. E.

1973-01-01

Investigations have continued into the possibility that significant information on stream flow rates can be obtained from aerial and satellite imagery of river meander patterns by seeking a correlation between the meander and discharge spectra of rivers. Such a correlation could provide the basis for a simple and inexpensive technique for remote sensing of the water resources of large geographical areas, eliminating the need for much hydrologic recording. The investigation of the nature of the meander and discharge spectra and their interrelationship can also contribute to a more fundamental understanding of the processes of both river meander formation and drainage of large basins. It has been found that floods decay with an inverse power law dependence on time. The exponent of this dependence varies from river to river and even from station to station along the same river. This power law time dependence makes possible the forecasting of river discharge with an uncertainty of about 5% for as long as a month following the flood peak.

Tracking changes of river morphology in Ayeyarwady River in Myanmar using earth observations and surface water mapping tool

NASA Astrophysics Data System (ADS)

Piman, T.; Schellekens, J.; Haag, A.; Donchyts, G.; Apirumanekul, C.; Hlaing, K. T.

2017-12-01

River morphology changes is one of the key issues in Ayeyarwady River in Myanmar which cause impacts on navigation, riverine habitats, agriculture lands, communities and livelihoods near the bank of the river. This study is aimed to track the changes in river morphology in the middle reach of Ayeyarwady River over last 30 years from 1984-2014 to improve understanding of riverbank dynamic, erosion and deposition procress. Earth observations including LandSat-7, LandSat-8, Digital Elevation Model from SRTM Plus and, ASTER-2 GoogleMap and Open Street Map were obtained for the study. GIS and remote sensing tools were used to analyze changes in river morphology while surface water mapping tool was applied to determine how the dynamic behaviour of the surface river and effect of river morphology changes. The tool consists of two components: (1) a Google Earth Engine (GEE) javascript or python application that performs image analysis and (2) a user-friendly site/app using Google's appspot.com that exposes the application to the users. The results of this study shown that the fluvial morphology in the middle reach of Ayeyarwady River is continuously changing under the influence of high water flows in particularly from extreme flood events and land use change from mining and deforestation. It was observed that some meandering sections of the riverbank were straightened, which results in the movement of sediment downstream and created new sections of meandering riverbank. Several large islands have formed due to the stabilization by vegetation and is enforced by sedimentation while many small bars were formed and migrated dynamically due to changes in water levels and flow velocity in the wet and dry seasons. The main channel was changed to secondary channel in some sections of the river. This results a constant shift of the navigation route. We also found that some villages were facing riverbank erosion which can force villagers to relocate. The study results demonstrated

Numerical modeling of gravel bed river response to meander straightening: The coupling between the evolution of bed pavement and long profile

NASA Astrophysics Data System (ADS)

Talbot, Tracey; Lapointe, Michel

2002-06-01

Artificial meander straightening (rectification) was conducted in the early 1960s along the Sainte-Marguerite River, Canada, in order to facilitate highway construction along the valley. Previous studies [Talbot and Lapointe, 2002] confirm that vertical reprofiling, coupled with pavement coarsening in the degrading reach, were the main responses counteracting the disequilibrium in gravel transport rates triggered at rectification of this system. Numerical simulations, using SEDROUT2.0, a one-dimensional hydraulic and sediment transport model, and validated against the observed channel response, show the important role played by an advancing wave of pavement coarsening down the rectified reach in modulating the bed degradation response. Simulations extending into the future reveal an asymptotically slowing approach to equilibrium in the middle of the 21st century, with a response half-time of the order of 10 years. In near-threshold gravel bed systems like the Sainte-Marguerite River, pavement coarsening after rectification buffers the system against extreme degradation. Most significantly for watershed management, this also appears to severely limit the extent of propagation of degradation upstream of the rectification.

A nonlinear model of flow in meandering submarine and subaerial channels

NASA Astrophysics Data System (ADS)

Imran, Jasim; Parker, Gary; Pirmez, Carlos

1999-12-01

A generalized model of flow in meandering subaqueous and subaerial channels is developed. The conservation equations of mass and momentum are depth/layer integrated, normalized, and represented as deviations from a straight base state. This allows the determination of integrable forms which can be solved at both linear and nonlinear levels. The effects of various flow and geometric parameters on the flow dynamics are studied. Although the model is not limited to any specific planform, this study focuses on sine-generated curves. In analysing the flow patterns, the turbidity current of the subaqueous case is simplified to a conservative density flow with water entrainment from above neglected. The subaqueous model thus formally corresponds to a subcritical or only mildly supercritical mud-rich turbidity current. By extension, however the analysis can be applied to a depositional or erosional current carrying sand that is changing only slowly in the streamwise direction. By bringing the subaqueous and subaerial cases into a common form, flow behaviour in the two environments can be compared under similar geometric and boundary conditions. A major difference between the two cases is the degree of superelevation of channel flow around bends, which is modest in the subaerial case but substantial in the subaqueous case. Another difference concerns Coriolis effects: some of the largest subaqueous meandering systems are so large that Coriolis effects can become important. The model is applied to meander bends on the youngest channel in the mid-fan region of the Amazon Fan and a mildly sinuous bend of the North-West Atlantic Mid-Ocean Channel. In the absence of specific data on the turbid flows that created the channel, the model can be used to make inferences about the flow, and in particular the range of values of flow velocity and sediment concentration that would allow the growth and downfan migration of meander bends.

Freedom Space for Rivers: A Sustainable Management Approach to Enhance River Resilience

NASA Astrophysics Data System (ADS)

Biron, Pascale M.; Buffin-Bélanger, Thomas; Larocque, Marie; Choné, Guénolé; Cloutier, Claude-André; Ouellet, Marie-Audray; Demers, Sylvio; Olsen, Taylor; Desjarlais, Claude; Eyquem, Joanna

2014-11-01

River systems are increasingly under stress and pressure from agriculture and urbanization in riparian zones, resulting in frequent engineering interventions such as bank stabilization or flood protection. This study provides guidelines for a more sustainable approach to river management based on hydrogeomorphology concepts applied to three contrasted rivers in Quebec (Canada). Mobility and flooding spaces are determined for the three rivers, and three levels of "freedom space" are subsequently defined based on the combination of the two spaces. The first level of freedom space includes very frequently flooded and highly mobile zones over the next 50 years, as well as riparian wetlands. It provides the minimum space for both fluvial and ecological functionality of the river system. On average for the three studied sites, this minimum space was approximately 1.7 times the channel width, but this minimum space corresponds to a highly variable width which must be determined from a thorough hydrogeomorphic assessment and cannot be predicted using a representative average. The second level includes space for floods of larger magnitude and provides for meanders to migrate freely over a longer time period. The last level of freedom space represents exceptional flood zones. We propose the freedom space concept to be implemented in current river management legislation because it promotes a sustainable way to manage river systems, and it increases their resilience to climate and land use changes in comparison with traditional river management approaches which are based on frequent and spatially restricted interventions.

Filament Tension and Phase Locking of Meandering Scroll Waves

NASA Astrophysics Data System (ADS)

Dierckx, Hans; Biktasheva, I. V.; Verschelde, H.; Panfilov, A. V.; Biktashev, V. N.

2017-12-01

Meandering spiral waves are often observed in excitable media such as the Belousov-Zhabotinsky reaction and cardiac tissue. We derive a theory for drift dynamics of meandering rotors in general reaction-diffusion systems and apply it to two types of external disturbances: an external field and curvature-induced drift in three dimensions. We find two distinct regimes: with small filament curvature, meandering scroll waves exhibit filament tension, whose sign determines the stability and drift direction. In the regimes of strong external fields or meandering motion close to resonance, however, phase locking of the meander pattern is predicted and observed.

Filament Tension and Phase Locking of Meandering Scroll Waves.

PubMed

Dierckx, Hans; Biktasheva, I V; Verschelde, H; Panfilov, A V; Biktashev, V N

2017-12-22

Meandering spiral waves are often observed in excitable media such as the Belousov-Zhabotinsky reaction and cardiac tissue. We derive a theory for drift dynamics of meandering rotors in general reaction-diffusion systems and apply it to two types of external disturbances: an external field and curvature-induced drift in three dimensions. We find two distinct regimes: with small filament curvature, meandering scroll waves exhibit filament tension, whose sign determines the stability and drift direction. In the regimes of strong external fields or meandering motion close to resonance, however, phase locking of the meander pattern is predicted and observed.

Denitrification in the Mississippi River network controlled by flow through river bedforms

USGS Publications Warehouse

Gomez-Velez, Jesus D.; Harvey, Judson W.; Cardenas, M. Bayani; Kiel, Brian

2015-01-01

Increasing nitrogen concentrations in the world’s major rivers have led to over-fertilization of sensitive downstream waters. Flow through channel bed and bank sediments acts to remove riverine nitrogen through microbe-mediated denitrification reactions. However, little is understood about where in the channel network this biophysical process is most efficient, why certain channels are more effective nitrogen reactors, and how management practices can enhance the removal of nitrogen in regions where water circulates through sediment and mixes with groundwater - hyporheic zones. Here we present numerical simulations of hyporheic flow and denitrification throughout the Mississippi River network using a hydrogeomorphic model. We find that vertical exchange with sediments beneath the riverbed in hyporheic zones, driven by submerged bedforms, has denitrification potential that far exceeds lateral hyporheic exchange with sediments alongside river channels, driven by river bars and meandering banks. We propose that geomorphic differences along river corridors can explain why denitrification efficiency varies between basins in the Mississippi River network. Our findings suggest that promoting the development of permeable bedforms at the streambed - and thus vertical hyporheic exchange - would be more effective at enhancing river denitrification in large river basins than promoting lateral exchange through induced channel meandering.

Potential for Small Unmanned Aircraft Systems applications for identifying groundwater-surface water exchange in a meandering river reach

USGS Publications Warehouse

Pai, H.; Malenda, H.; Briggs, Martin A.; Singha, K.; González-Pinzón, R.; Gooseff, M.; Tyler, S.W.; ,

2017-01-01

The exchange of groundwater and surface water (GW-SW), including dissolved constituents and energy, represents a critical yet challenging characterization problem for hydrogeologists and stream ecologists. Here, we describe the use of a suite of high spatial-resolution remote-sensing techniques, collected using a small unmanned aircraft system (sUAS), to provide novel and complementary data to analyze GW-SW exchange. sUAS provided centimeter-scale resolution topography and water surface elevations, which are often drivers of exchange along the river corridor. Additionally, sUAS-based vegetation imagery, vegetation-top elevation, and normalized difference vegetation index (NDVI) mapping indicated GW-SW exchange patterns that are difficult to characterize from the land surface and may not be resolved from coarser satellite-based imagery. We combined these data with estimates of sediment hydraulic conductivity to provide a direct estimate of GW “shortcutting” through meander necks, which was corroborated by temperature data at the riverbed interface.

Potential for Small Unmanned Aircraft Systems Applications for Identifying Groundwater-Surface Water Exchange in a Meandering River Reach

NASA Astrophysics Data System (ADS)

Pai, H.; Malenda, H. F.; Briggs, M. A.; Singha, K.; González-Pinzón, R.; Gooseff, M. N.; Tyler, S. W.

2017-12-01

The exchange of groundwater and surface water (GW-SW), including dissolved constituents and energy, represents a critical yet challenging characterization problem for hydrogeologists and stream ecologists. Here we describe the use of a suite of high spatial resolution remote sensing techniques, collected using a small unmanned aircraft system (sUAS), to provide novel and complementary data to analyze GW-SW exchange. sUAS provided centimeter-scale resolution topography and water surface elevations, which are often drivers of exchange along the river corridor. Additionally, sUAS-based vegetation imagery, vegetation-top elevation, and normalized difference vegetation index mapping indicated GW-SW exchange patterns that are difficult to characterize from the land surface and may not be resolved from coarser satellite-based imagery. We combined these data with estimates of sediment hydraulic conductivity to provide a direct estimate of GW "shortcutting" through meander necks, which was corroborated by temperature data at the riverbed interface.

Spawning migration movements of Lost River and shortnose suckers in the Williamson and Sprague Rivers, Oregon, following the removal of Chiloquin Dam-2009 Annual Report

USGS Publications Warehouse

Ellsworth, Craig M.; VanderKooi, Scott P.

2011-01-01

The Chiloquin Dam was located at river kilometer (rkm) 1.3 on the Sprague River near the town of Chiloquin, Oregon. The dam was identified as a barrier that potentially inhibited or prevented the upstream spawning migrations and other movements of endangered Lost River suckers (Deltistes luxatus), shortnose suckers (Chasmistes brevirostris), and other fish in the Sprague River. Our research objectives in 2009 were to evaluate adult catostomid spawning migration patterns using radio telemetry to identify and describe shifts in spawning area distribution and migration behavior following the removal of Chiloquin Dam in 2008. We attached external radio transmitters to 58 Lost River suckers and 59 shortnose suckers captured at the Williamson River fish weir. A total of 17 radio-tagged Lost River suckers and one radio-tagged shortnose sucker were detected approaching the site of the former Chiloquin Dam but only two radio-tagged fish (one male Lost River sucker and one female Lost River sucker) were detected crossing upstream of the dam site. A lower proportion of radio-tagged shortnose suckers were detected migrating into the Sprague River when compared with previous years. Detections on remote passive integrated transponder (PIT) tag arrays located in the Sprague River show that although the proportion of fish coming into the Sprague River is small when compared to the number of fish crossing the Williamson River fish weir, the number of fish migrating upstream of the Chiloquin Dam site increased exponentially in the first year since its removal. These data will be used in conjunction with larval production and adult spawning distribution data to evaluate the effectiveness of dam removal in order to provide increased access to underutilized spawning habitat located further upstream in the Sprague River and to reduce the crowding of spawning fish below the dam site.

Hydrodynamics and sediment transport in a meandering channel with a model axial-flow hydrokinetic turbine

NASA Astrophysics Data System (ADS)

Hill, Craig; Kozarek, Jessica; Sotiropoulos, Fotis; Guala, Michele

2016-02-01

An investigation into the interactions between a model axial-flow hydrokinetic turbine (rotor diameter, dT = 0.15 m) and the complex hydrodynamics and sediment transport processes within a meandering channel was carried out in the Outdoor StreamLab research facility at the University of Minnesota St. Anthony Falls Laboratory. This field-scale meandering stream with bulk flow and sediment discharge control provided a location for high spatiotemporally resolved measurements of bed and water surface elevations around the model turbine. The device was installed within an asymmetric, erodible channel cross section under migrating bed form and fixed outer bank conditions. A comparative analysis between velocity and topographic measurements, with and without the turbine installed, highlights the local and nonlocal features of the turbine-induced scour and deposition patterns. In particular, it shows how the cross-section geometry changes, how the bed form characteristics are altered, and how the mean flow field is distorted both upstream and downstream of the turbine. We further compare and discuss how current energy conversion deployments in meander regions would result in different interactions between the turbine operation and the local and nonlocal bathymetry compared to straight channels.

Self-Formed Meanders (With Cutoffs) in a Laboratory Flume

NASA Astrophysics Data System (ADS)

Braudrick, C. A.; Leverich, G. T.; Sklar, L. S.; Dietrich, W. E.

2005-12-01

The development of a mechanistic understanding of channel geometry and morphodynamics has been inhibited by the inability to create self-formed, freely meandering, single thread channels in a laboratory flume. By being able to reliably generate such channels, studies of the influence of sediment supply and flow dynamics as well as bank strength on channel morphology can be experimentally explored. We have found that the key experimental controls are: 1) ratio of bank strength to boundary shear stress exerted on the bank; 2) bedload and suspended load rates; and 3) variable flow discharge. We have been able to create meandering channels in a sand bedded laboratory flume using alfalfa sprouts. The alfalfa sprouts decrease the bank erosion rate so that bank erosion would occur at approximately the same pace as bar growth. The addition of coarse suspended load was necessary to cause deposition on bars to grow to the floodplain height. The sprouts contributed to deposition by creating a rough floodplain surface. Steady discharge failed to produced meandering, apparently due to the lack of suspended load deposition on the bar surface. The channels were created in a 3.6-m wide and 6.1-m long flume with an adjustable slope set at 0.01. We introduced both bedload (sand) and suspended load (crushed silica) into the top of the flume, which has an initial channel with either one or two bends carved into the floodplain. Runs lasted between 1 and 4 hours and occurred once per week. Alfalfa seeds were spread evenly outside the low flow channel following each run and are allowed to grow between runs. With the same material and flow conditions, the channel rapidly braided without the alfalfa sprouts. Braided was also favored under steady flow conditions. Under dynamic flows with banks strengthened by sprouts, the resulting experimental channels had many of the features observed in meandering streams such as oxbow lakes and meander cutoffs. The cutoffs occurred during overbank flows

Analysis of impediments to spawning migrations of anadromous fishes in Virginia rivers : final report.

DOT National Transportation Integrated Search

1985-01-01

The historic and present ranges of anadromous alosids and striped bass were determined for three of Virginia's rivers. American shad, blueback herring, and alewives migrated to at least Remington (river mile 188) on the Rappahannock River. They ascen...

Denitrification in the Mississippi River network controlled by flow through river bedforms

USGS Publications Warehouse

Gomez-Velez, Jesus D.; Harvey, Judson W.; Cardenas, M. Bayani; Kiel, Brian

2015-01-01

Increasing nitrogen concentrations in the world’s major rivers have led to over-fertilization of sensitive downstream waters1, 2, 3, 4. Flow through channel bed and bank sediments acts to remove riverine nitrogen through microbe-mediated denitrification reactions5, 6, 7, 8, 9, 10. However, little is understood about where in the channel network this biophysical process is most efficient, why certain channels are more effective nitrogen reactors, and how management practices can enhance the removal of nitrogen in regions where water circulates through sediment and mixes with groundwater - hyporheic zones8, 11, 12. Here we present numerical simulations of hyporheic flow and denitrification throughout the Mississippi River network using a hydrogeomorphic model. We find that vertical exchange with sediments beneath the riverbed in hyporheic zones, driven by submerged bedforms, has denitrification potential that far exceeds lateral hyporheic exchange with sediments alongside river channels, driven by river bars and meandering banks. We propose that geomorphic differences along river corridors can explain why denitrification efficiency varies between basins in the Mississippi River network. Our findings suggest that promoting the development of permeable bedforms at the streambed - and thus vertical hyporheic exchange - would be more effective at enhancing river denitrification in large river basins than promoting lateral exchange through induced channel meandering. 

Magnetic fingerprint of the sediment load in a meander bend section of the Seine River (France)

NASA Astrophysics Data System (ADS)

Kayvantash, D.; Cojan, I.; Kissel, C.; Franke, C.

2017-06-01

This study aims to evaluate the potential of magnetic methods to determine the composition of the sediment load in a cross section of an unmanaged meander in the upstream stretch of the Seine River (Marnay-sur-Seine). Suspended particulate matter (SPM) was collected based on a regular sampling scheme along a cross section of the river, at two different depth levels: during a low-water stage (May 2014) and a high-water stage (February 2015). Riverbed sediments (RBS) were collected during the low-water stage and supplementary samples were taken from the outer and inner banks. Magnetic properties of the dry bulk SPM and sieved RBS and bank sediments were analysed. After characterizing the main magnetic carrier as magnetite, hysteresis parameters were measured, giving access to the grain size and the concentration of these magnetite particles. The results combined with sedimentary grain size data were compared to the three-dimensional velocity profile of the river flow. In the RBS where the magnetic grain size is rather uniform, the concentration of magnetite is inversely proportional to the mean grain size of the total sediment indicating that magnetite is strongly associated with the fine sedimentary fraction. The same pattern is observed in the samples from the outer and inner banks. During the low-water stage, the uniformly fine SPM grain size distribution characterizes the wash load. The magnetic fraction is also relatively fine (within the pseudo single domain range) with concentration similar to that of the fine RBS fraction. During the high-water stage, SPM samples correspond to mixtures of wash load and resuspended sediment from the bedload and riverbanks. Here, the grain size distribution is heterogeneous across the section showing coarser particles compared to those in the low-water stage and more varying magnetite concentrations while the magnetic grain size is like that of the low-water stage. The magnetite concentration in the high-water SPM can be

Upstream migration of Pacific lampreys in the John Day River, Oregon: Behavior, timing, and habitat use

USGS Publications Warehouse

Robinson, T. Craig; Bayer, J.M.

2005-01-01

Adult Pacific lamprey migration and habitat preferences for over-winter holding and spawning, and larval rearing in tributaries to the Columbia River are not well understood. The John Day River is one such tributary where larval and adult stages of this species have been documented, and its free-flowing character provided the opportunity to study migration of Pacific lampreys unimpeded by passage constraints. Forty-two adult Pacific lampreys were captured in the John Day River near its mouth during their upstream migration. Pacific lampreys were surgically implanted with radio transmitters and released onsite, and tracked by fixed-site, aerial, and terrestrial telemetry methods for nearly one year. Adults moved upstream exclusively at night, with a mean rate of 11.1 ?? 6.3 km/day. They halted upstream migration by September, and held a single position for approximately six months in the lateral margins of riffles and glides, using boulders for cover. More than half of Pacific lampreys resumed migration in March before ending movement in early May. Pacific lampreys that resumed migration in spring completed a median of 87% of their upstream migration before over-winter holding. Upon completing migration. Pacific lampreys briefly held position before beginning downstream movement at the end of May. Though not directly observed, halting migration and movement downstream were likely the result of spawning and death. Gains in adult Pacific lamprey passage through the Columbia River hydrosystem and tributaries may be made by improvements that would expedite migration during spring and summer and increase the quantity and variety of cover and refuge opportunities. ?? 2005 by the Northwest Scientific Association. All rights reserved.

Seasonal migration and homing of channel catfish in the lower Wisconsin River, Wisconsin

USGS Publications Warehouse

Pellett, Thomas D.; Van Dyck, Gene J.; Adams, Jean V.

1998-01-01

A multiyear tag and recapture study was conducted to determine whether channel catfishIctalurus punctatus were migratory and if they had strong homing tendencies. Over 10,000 channel catfish were tagged from the lower Wisconsin River and adjacent waters of the upper Mississippi River during the 3-year sampling period. Data on movements were obtained from study recaptures and through tag returns and harvest information provided by sport anglers and commercial fishers. Channel catfish occupied relatively small home ranges during summer, migrated downstream to the upper Mississippi River in autumn, then migrated back up the Wisconsin River in spring to spawn and to occupy the same summer home sites they had used in previous summers. Fish size was a factor in the degree of fidelity to summer home sites, with larger fish showing greater fidelity.

[Ethnic dimension to migration in the Senegal river valley].

PubMed

Traore, S

1993-08-01

Studies of the factors determining migratory patterns in the Senegal River Valley usually stress the importance of economic factors related to colonial domination. But when cultural factors and the social relations governing them are examined in a comparative study of ethnic groups, distinct population subgroups may be revealed to have differential migratory patterns. The Soninka and the Poular, two groups highly affected by migration, were chosen for an analysis of the impact of specific historical experiences on migratory behavior. A historical analysis of colonial archives and anthropological and historical monographs and the 1982-83 "Survey of Migration in the Valley of the Senegal River" provided data. The survey indicated that Soninka and Poular migratory patterns differed from each other, but that both differed from the migratory patterns of all other ethnic groups in the region. Soninka migration is international and oriented primarily toward Europe. It has recently become more intense than that of the poular. The determinants of migration in the two groups appear related more to the structure of households than to lack of educational and health facilities or even of food at the village level. Pastoral life and its associated beliefs and religious ideology appear to have been the principal determinants of precolonial movement among the Poular, while Soninka migration responded more to competition over control of manpower. Itinerant commercial activity was coupled with use of slave labor to ensure food production. But the suppression of slavery and crises of subsistence aggravated by colonial policy provoked ever more distant migration, which found a focus in the French demand for labor after World War II. Migration as an alternative does not appear to have been as significant for the Poular until more recently, when subsistence agriculture and the sale of animals were no longer sufficient to cover monetary needs. Male migration among the Soninka is a

Environmental correlates of upstream migration of yellow-phase American eels in the Potomac River drainage

USGS Publications Warehouse

Welsh, Stuart A.; Heather L. Liller,

2013-01-01

Assessing the relationships between upstream migration and environmental variables is important to understanding the ecology of yellow-phase American Eels Anguilla rostrata. During an American Eel migration study within the lower Shenandoah River (Potomac River drainage), we counted and measured American Eels at the Millville Dam eel ladder for three periods: 14 May–23 July 2004, 7–30 September 2004, and 1 June–31 July 2005. Using generalized estimating equations, we modeled each time series of daily American Eel counts by fitting time-varying environmental covariates of lunar illumination (LI), river discharge (RD), and water temperature (WT), including 1-d and 2-d lags of each covariate. Information-theoretic approaches were used for model selection and inference. A total of 4,847 American Eels (19–74 cm total length) used the ladder during the three periods, including 2,622 individuals during a 2-d span following a hurricane-induced peak in river discharge. Additive-effects models of RD + WT, a 2-d lag of LI + RD, and LI + RD were supported for the three periods, respectively. Parameter estimates were positive for river discharge for each time period, negative for lunar illumination for two periods and positive for water temperature during one period. Additive-effects models supported synergistic influences of environmental variables on the upstream migration of yellow-phase American Eels, although river discharge was consistently supported as an influential correlate of upstream migration.

Influence of Tectonics on the Channel Pattern of Alaknanda River in Srinagar Valley (Garhwal Himalaya)

NASA Astrophysics Data System (ADS)

Datt, Devi

2017-04-01

This paper describes the results of a continuing investigation of tectonic influence on channel pattern and morphology of Alaknanda River in Lesser Garhwal Himalaya, Uttarakhand, India. Extensive field investigations using conventional methods supported by topographical sheets and remote sensing data (LISS IV), were undertaken.The results are classified into three sections :- tectonics, channel pattern and impact of tectonics on channel pattern. The channel length is divided into 8 meanders sets of 3 segments from Supana to Kirtinagar. Thereafter, a litho-tectonic map of the Srinagar valley was prepared. The style of active tectonics on deformation and characterization of fluvial landscape was investigated on typical strike-slip transverse faults near the zone of North Almora Thrust (NAT). NAT is a major tectonic unit of the Lesser Himalaya which passes through the northern margin from NW to SE direction.. The structural and lithological controls on the Alaknanda River system in Srinagar valley are reflected on distinct drainage patterns, abrupt change in flow direction, incised meandering, offset river channels, straight river lines, palaeo-channels, multi levels of terraces, knick points and pools in longitudinal profile. The results of the study show that the sinuosity index of the river is 1.35. Transverse faulting is very common along the NAT. An earlier generation of linear tectonic features were displaced by the latter phase of deformation. Significant deviations were observed in river channel at deformation junctions. Moreover, all 8 sets of meanders are strongly influenced by tectonic features. The meandering course is, thereby, correlated with tectonic features. It is shown that the river channel is strongly influenced by the tectonic features in the study area. Key Words: Tectonic, Meander, Channel pattern, deformation, Knick point.

Secondary Circulation Asymmetry in a Meandering, Partially Stratified Estuary

NASA Astrophysics Data System (ADS)

Pein, J.; Valle-Levinson, A.; Stanev, E. V.

2018-03-01

Numerical model experiments are used to study the effects of multiple channel bends on estuarine dynamics and, in particular, on secondary flows. These effects are demonstrated by comparing experiments with two different idealized trumpet-shaped estuaries, one straight and another one with a ˜8 km meandering section in the middle of the estuary. Meanders complicate the flow field by introducing secondary processes. For instance, meanders increase turbulence and associated mixing locally within the water column, as well as outside the meandering portion. Furthermore, meanders transform up to 30% of the along-channel momentum into secondary circulation. Production of turbulence and secondary currents is different at flood and ebb tidal phases. At flood, meanders lead to unstable stratification and increased turbulence. At ebb, the flow develops a helical pattern and adjusts to the channel curvature with minimal decrease in density stability. The secondary circulation asymmetry is caused by an interplay between the across-channel baroclinic pressure gradient force and the centrifugal force. During ebb both forces enhance each other, whereas they oppose during flood. As a consequence of this interaction between baroclinic forcing and curving morphology, ebb flows and horizontal buoyancy fluxes increase relative to flood. The enhanced ebb dominance shifts a density front toward the mouth of the estuary, thus reducing salt intrusion.

[Downstream migration, behavior, and distribution of fish fry in the lower reaches of the Ozernaya River (southwestern Kamchatka)].

PubMed

Pavlov, D S; Kirillova, E A; Kirillov, P I; Nezdoliĭ, V K

2015-01-01

Fry of five species of salmonids are found in the lower reaches of the Ozernaya River. The most abundant are chum salmon and pink salmon which compose the bulk of fry which migrate downstream from the river to the sea. The dates and duration of migration of particular species differed according to the specific traits of their biology. Pink salmon is characterized by a simple migration strategy: it migrated downstream in a short time after emergence from theground. Chum salmon has two strategies of downstream migration: some fry start migration soon after emergence, and others remained in the river for several weeks. Downstream migration of pink salmon occurred mainly at night in contrast to that of chum salmon, over 24 h, the part of daytime increased with growth, of the fish. Migration of pink salmon was passive. Passive migration of chum salmon changed into active-passive with growth of the fish. The ratio of fish in the inshore zone and in the current was different in the course of 24 h. The number of fish in the inshore zone decreased in the period of intensive downstream migration.

Assessing geomorphic sensitivity in relation to river capacity for adjustment

NASA Astrophysics Data System (ADS)

Reid, H. E.; Brierley, G. J.

2015-12-01

River sensitivity describes the nature and rate of channel adjustments. An approach to analysis of geomorphic river sensitivity outlined in this paper relates potential sensitivity based on the expected capacity of adjustment for a river type to the recent history of channel adjustment. This approach was trialled to assess low, moderate and high geomorphic sensitivity for four different types of river (10 reaches in total) along the Lower Tongariro River, North Island, New Zealand. Building upon the River Styles framework, river types were differentiated based upon valley setting (width and confinement), channel planform, geomorphic unit assemblages and bed material size. From this, the behavioural regime and potential for adjustment (type and extent) were determined. Historical maps and aerial photographs were geo-rectified and the channel planform digitised to assess channel adjustments for each reach from 1928 to 2007. Floodplain width controlled by terraces, exerted a strong influence upon reach scale sensitivity for the partly-confined, wandering, cobble-bed river. Although forced boundaries occur infrequently, the width of the active channel zone is constrained. An unconfined braided river reach directly downstream of the terrace-confined section was the most geomorphically sensitive reach. The channel in this reach adjusted recurrently to sediment inputs that were flushed through more confined, better connected upstream reaches. A meandering, sand-bed river in downstream reaches has exhibited negligible rates of channel migration. However, channel narrowing in this reach and the associated delta indicate that the system is approaching a threshold condition, beyond which channel avulsion is likely to occur. As this would trigger more rapid migration, this reach is considered to be more geomorphically sensitive than analysis of its low migration rate alone would indicate. This demonstrates how sensitivity is fashioned both by the behavioural regime of a reach

Movement and spawning of American shad transported above dams on the Roanoke River, North Carolina and Virginia

USGS Publications Warehouse

Harris, Julianne E.; Hightower, Joseph E.

2011-01-01

American shad Alosa sapidissima are in decline throughout much of their native range as a result of overfishing, pollution, and habitat alteration in coastal rivers where they spawn. One approach to restoration in regulated rivers is to provide access to historical spawning habitat above dams through a trap-and-transport program. We examined the initial survival, movement patterns, spawning, and downstream passage of sonic-tagged adult American shad transported to reservoir and riverine habitats upstream of hydroelectric dams on the Roanoke River, North Carolina and Virginia, during 2007–2009. Average survival to release in 2007–2008 was 85%, but survival decreased with increasing water temperature. Some tagged fish released in reservoirs migrated upstream to rivers; however, most meandered back and forth within the reservoir. A higher percentage of fish migrated through a smaller (8,215-ha) than a larger (20,234-ha) reservoir, suggesting that the population-level effects of transport may depend on upper basin characteristics. Transported American shad spent little time in upper basin rivers but were there when temperatures were appropriate for spawning. No American shad eggs were collected during weekly plankton sampling in upper basin rivers. The estimated initial survival of sonic-tagged American shad after downstream passage through each dam was 71–100%; however, only 1% of the detected fish migrated downstream through all three dams and many were relocated just upstream of a dam late in the season. Although adult American shad were successfully transported to upstream habitats in the Roanoke River basin, under present conditions transported individuals may have reduced effective fecundity and postspawning survival compared with nontransported fish that spawn in the lower Roanoke River.

Movement Patterns of American Shad Transported Upstream of Dams on The Roanoke River, North Carolina and Virginia

USGS Publications Warehouse

Harris, Julianne E.; Hightower, J.E.

2011-01-01

American shad Alosa sapidissima are in decline throughout much of their native range as a result of overfishing, pollution, and habitat alteration in coastal rivers where they spawn. One approach to restoration in regulated rivers is to provide access to historical spawning habitat above dams through a trap-and-transport program. We examined the initial survival, movement patterns, spawning, and downstream passage of sonic-tagged adult American shad transported to reservoir and riverine habitats upstream of hydroelectric dams on the Roanoke River, North Carolina and Virginia, during 2007–2009. Average survival to release in 2007–2008 was 85%, but survival decreased with increasing water temperature. Some tagged fish released in reservoirs migrated upstream to rivers; however, most meandered back and forth within the reservoir. A higher percentage of fish migrated through a smaller (8,215-ha) than a larger (20,234-ha) reservoir, suggesting that the population-level effects of transport may depend on upper basin characteristics. Transported American shad spent little time in upper basin rivers but were there when temperatures were appropriate for spawning. No American shad eggs were collected during weekly plankton sampling in upper basin rivers. The estimated initial survival of sonic-tagged American shad after downstream passage through each dam was 71–100%; however, only 1% of the detected fish migrated downstream through all three dams and many were relocated just upstream of a dam late in the season. Although adult American shad were successfully transported to upstream habitats in the Roanoke River basin, under present conditions transported individuals may have reduced effective fecundity and postspawning survival compared with nontransported fish that spawn in the lower Roanoke River.

Correlation between river slope and meandering variability (obtained by DGPS data) and morphotectonics for two Andean tributaries of the Amazon river: the case of Beni (Bolivia) and Napo (Ecuador-Peru) rivers.

NASA Astrophysics Data System (ADS)

Bourrel, L.; Darrozes, J.; Guyot, J.; Christophoul, F.; Bondoux, F.

2007-05-01

The Beni river drains a catchment area of 282 000 km2 of which 40 percent are located in the Cordillera of the Bolivian and Peruvian Andes, and the rest in the Amazonian plain : the studied reaches runs from Guanay (Andean Piedmont) to Riberalta (junction with Madre de Dios river) that represents a distance by the river of 1055 km. The Napo river starts in the Ecuadorian Andes and leaves Ecuador in Nuevo Rocafuerte (27 400 km2) and enters in Peru until its junction with the Amazon river : the studied section runs from Misahualli (Andean Piedmont) to this junction, that represents a distance by the river of 995 km. The GPS data were acquired using a mobile GPS embarked on a boat and 4 fixed bases located along the Beni river, 6 along the Napo river and the two rivers profile calculated from post-treated differential GPS solutions. For the Beni river, two sectors were identified: - the upstream sector (~230 km) between Guanay (414 m) and 50 km downstream Rurrenabaque (245 m) is located in Andean Piedmont, which consists in a series of thrusts associated with anticlines and synclines (the subandean zone), and presents slope values range between 135 cm/km and 10 cm/km and an average index of sinuosity (IS) of 1.29, - the downstream sector (~ 820 km) which runs in Amazonian plain (until Riberalta -165 m-), is characterized by an average slope of 8 cm/km and an average IS of 2.06 (this sector is much more homogeneous and the Beni river shows a meandering channel). For the Napo River, three sectors were identified: - the first sector (~140 km) between Misahualli (401 m) and Coca (265 m), is located in Andean Piedmont (subandean zone) and presents slope values range between 170 cm/km and 30 cm/km and an average IS of 1.6, - the second sector (~250 km) between Coca (when the Napo river enters in the Amazonian plain) and Nuevo Rocafuerte (190 m), presents slope values range between 30 cm/km and 20 cm/km and an average IS of 1.2, and a convex-up shape profile corresponding to

Distributed meandering waveguides (DMWs) for novel photonic circuits (Conference Presentation)

NASA Astrophysics Data System (ADS)

Dag, Ceren B.; Anil, Mehmet Ali; Serpengüzel, Ali

2017-05-01

Meandering waveguide distributed feedback structures are novel integrated photonic lightwave and microwave circuit elements. Meandering waveguide distributed feedback structures with a variety of spectral responses can be designed for a variety of lightwave and microwave circuit element functions. Distributed meandering waveguide (DMW) structures [1] show a variety of spectral behaviors with respect to the number of meandering loop mirrors (MLMs) [2] used in their composition as well as their internal coupling constants (Cs). DMW spectral behaviors include Fano resonances, coupled resonator induced transparency (CRIT), notch, add-drop, comb, and hitless filters. What makes the DMW special is the self-coupling property intrinsic to the DMW's nature. The basic example of DMW's nature is motivated through the analogy between the so-called symmetric meandering resonator (SMR), which consists of two coupled MLMs, and the resonator enhanced Mach-Zehnder interferometer (REMZI) [3]. A SMR shows the same spectral characteristics of Fano resonances with its self-coupling property, similar to the single, distributed and binary self coupled optical waveguide (SCOW) resonators [4]. So far DMWs have been studied for their electric field intensity, phase [5] and phasor responses [6]. The spectral analysis is performed using the coupled electric field analysis and the generalization of single meandering loop mirrors to multiple meandering distributed feedback structures is performed with the transfer matrix method. The building block of the meandering waveguide structures, the meandering loop mirror (MLM), is the integrated analogue of the fiber optic loop mirrors. The meandering resonator (MR) is composed of two uncoupled MLM's. The meandering distributed feedback (MDFB) structure is the DFB of the MLM. The symmetric MR (SMR) is composed of two coupled MLM's, and has the characteristics of a Fano resonator in the general case, and tunable power divider or tunable hitless filter

Annual mass drownings of the Serengeti wildebeest migration influence nutrient cycling and storage in the Mara River

PubMed Central

Rosi, Emma J.; Post, David M.

2017-01-01

The annual migration of ∼1.2 million wildebeest (Connochaetes taurinus) through the Serengeti Mara Ecosystem is the largest remaining overland migration in the world. One of the most iconic portions of their migration is crossing of the Mara River, during which thousands drown annually. These mass drownings have been noted, but their frequency, size, and impact on aquatic ecosystems have not been quantified. Here, we estimate the frequency and size of mass drownings in the Mara River and model the fate of carcass nutrients through the river ecosystem. Mass drownings (>100 individuals) occurred in at least 13 of the past 15 y; on average, 6,250 carcasses and 1,100 tons of biomass enter the river each year. Half of a wildebeest carcass dry mass is bone, which takes 7 y to decompose, thus acting as a long-term source of nutrients to the Mara River. Carcass soft tissue decomposes in 2–10 wk, and these nutrients are mineralized by consumers, assimilated by biofilms, transported downstream, or moved back into the terrestrial ecosystem by scavengers. These inputs comprise 34–50% of the assimilated diet of fish when carcasses are present and 7–24% via biofilm on bones after soft tissue decomposition. Our results show a terrestrial animal migration can have large impacts on a river ecosystem, which may influence nutrient cycling and river food webs at decadal time scales. Similar mass drownings may have played an important role in rivers throughout the world when large migratory herds were more common features of the landscape. PMID:28630330

Low-frequency meandering piezoelectric vibration energy harvester.

PubMed

Berdy, David F; Srisungsitthisunti, Pornsak; Jung, Byunghoo; Xu, Xianfan; Rhoads, Jeffrey F; Peroulis, Dimitrios

2012-05-01

The design, fabrication, and characterization of a novel low-frequency meandering piezoelectric vibration energy harvester is presented. The energy harvester is designed for sensor node applications where the node targets a width-to-length aspect ratio close to 1:1 while simultaneously achieving a low resonant frequency. The measured power output and normalized power density are 118 μW and 5.02 μW/mm(3)/g(2), respectively, when excited by an acceleration magnitude of 0.2 g at 49.7 Hz. The energy harvester consists of a laser-machined meandering PZT bimorph. Two methods, strain-matched electrode (SME) and strain-matched polarization (SMP), are utilized to mitigate the voltage cancellation caused by having both positive and negative strains in the piezoelectric layer during operation at the meander's first resonant frequency. We have performed finite element analysis and experimentally demonstrated a prototype harvester with a footprint of 27 x 23 mm and a height of 6.5 mm including the tip mass. The device achieves a low resonant frequency while maintaining a form factor suitable for sensor node applications. The meandering design enables energy harvesters to harvest energy from vibration sources with frequencies less than 100 Hz within a compact footprint.

Bathymetric surveys of the Kootenai River near Bonners Ferry, Idaho, water year 2011

USGS Publications Warehouse

Fosness, Ryan L.

2013-01-01

In 2009, the Kootenai Tribe of Idaho released and implemented the Kootenai River Habitat Restoration Master Plan. This plan aimed to restore, enhance, and maintain the Kootenai River habitat and landscape to support and sustain habitat conditions for aquatic species and animal populations. In support of these restoration efforts, the U.S. Geological Survey, in cooperation with the Kootenai Tribe of Idaho, conducted high-resolution multibeam echosounder bathymetric surveys in May, June, and July 2011, as a baseline bathymetric monitoring survey on the Kootenai River near Bonners Ferry, Idaho. Three channel patterns or reaches exist in the study area—braided, meander, and a transitional zone connecting the braided and meander reaches. Bathymetric data were collected at three study areas in 2011 to provide: (1) surveys in unmapped portions of the meander reach; (2) monitoring of the presence and extent of sand along planned lines within a section of the meander reach; and (3) monitoring aggradation and degradation of the channel bed at specific cross sections within the braided reach and transitional zone. The bathymetric data will be used to update and verify flow models, calibrate and verify sediment transport modeling efforts, and aid in the biological assessment in support of the Kootenai River Habitat Restoration Master Plan. The data and planned lines for each study reach were produced in ASCII XYZ format supported by most geospatial software.

Why do seif dunes meander?

NASA Astrophysics Data System (ADS)

Kryger, Mateusz; Bubenzer, Olaf; Parteli, Eric

2017-04-01

Seif dunes - which develop in the absence of vegetation and elongate in the resultant sand transport direction - are the prevailing dune type in many deserts of Earth and Mars and display a meandering shape that has challenged geomorphologists for decades. Understanding the factors controlling seif dune morphology may have impact for a broad range of scientific areas, in particular in the investigation of planetary wind regimes, as dune shape is primarily affected by wind directionality. Sand roses of areas hosting seif dunes display, in general, two main wind directions that form a divergence angle larger than 90˚ . Indeed, theory of dune formation predicts that longitudinal alignment of aeolian bedforms occurs under obtuse bimodal winds, a prediction that has been confirmed by field observations and numerical simulations of aeolian dunes, as well as by experiments on subaqueous bedforms. However, numerical simulations and water tank experiments performed under conditions of bimodal flows could never reproduce one of the most salient characteristics of the seif dune shape, which is its meandering. Instead, longitudinal dunes produced in such simulations and experiments display an unrealistic straight shape, which elongates into the resultant transport trend without developing the sinuous morphology of the seif dunes. Here we show, by means of morphodynamic modeling of aeolian sediment transport and dune formation under directionally varying flows, that the meandering shape of seif dunes can be explained by the action of subordinated sand-moving winds, which occur in addition to both main wind components of the bimodal wind. Because such subordinated winds - inherent to most measured sand roses of seif dune fields - are associated with transport rates much smaller than the sand flux values of the main bimodal wind components - they have been long thought to be negligible for dune shape. However, our simulations show that meandering may be caused by a single

Morphodynamics of Migration Surveyed at Large Spatial and Temporal Scales

NASA Astrophysics Data System (ADS)

Aalto, R.; Schwendel, A.; Nicholas, A. P.

2012-04-01

The controls on rivers migration are diverse and often complex. One way forwards is to select study rivers that meet certain simplifying conditions: near-pristine (no anthropogenic complications), large size and rapid mobility (resulting in significant change viewable in Landsat imagery), limited geological complexity (no bedrock), steady hydrology (relatively little variation in discharge and sediment load), and simplified base level control (no tides or other substantial perturbations). Such systems could then be measured at appropriate spatial and temporal scales to extract the reach-scale dynamics while averaging out the more stochastic behaviour of individual meander bends. Such an approach requires both special rivers and novel techniques, which we have investigated and present here. The two explored examples are the near-pristine Beni River basin in northern Bolivia (800 km channel length) and the similarly natural Fly-Strickland River basin in Papua New Guinea (400 km channel length) - large, tropical sand-bedded rivers that meet the above criteria. First, we conducted a GIS analysis of migration using image collections that include 1950s military aerial reconnaissance -- this allowed us to characterize mobility decades before the first Landsat satellite was launched. Following this approach, we characterized migration rate, sinuosity, and other parameters at the reach scale of 10km and the temporal scale of 50+ years, with clear patterns of rate and morphology emerging as a function of location within the systems. We conducted extensive fieldwork to explore potential controls on these patterns, with the focus of this talk being the results from DGPS surveys of river and valley slope. The length scale of these rivers, the density of the forested floodplains, and the hostility of the environments precluded the use of standard RTK-DGPS methods. Instead, we employed three novel techniques for long baseline (100s of km) DGPS surveys: OmniStar HP/XP GLONASS

Morphological change on the River Towy, Wales assessed using aerial photogrammetry

NASA Astrophysics Data System (ADS)

Ahmed, Joshua; Hodge, Michael

2017-04-01

The dynamic nature of meandering channels has fascinated geomorphologists for decades; with the onset of remote sensing, and technological advances in field equipment, scientists are able to capture high-resolution data from the Earth's surface using cost-effective techniques that require minimal manual labour. Here we present a morphological assessment of three meander bends on the River Towy, Wales, using aerial photography captured by the Welsh Assembly Government and supplemented by data captured by a UAV. Migration rates and changes in channel length were measured between 1969 and 2016 and compared to a coupled discharge record to quantify the effects of discharge variability on the morphological evolution of the channel. A short-term (seasonal) assessment of channel change was conducted by comparing sub-metre resolution 3D point cloud and digital elevation models, generated using a UAV and Structure-from-Motion (SfM) photogrammetry. Our results suggest that discharge variability plays a crucial role in controlling the evolution of meandering planforms and can be an effective means of excavating floodplain material over relatively short timescales, although erosion rates can be suppressed by bankline roughness, which effectively disrupts outwardly directed flow momentum. These findings have implications for land managers and those modelling the effects of climate change on hydrological regimes which are ultimately used to forecast channel planform changes. Additionally, our results demonstrate the potential of low-cost field surveying techniques in producing high resolution models of landscape change.

Migrations and swimming capabilities of endangered pallid sturgeon (Scaphirhynchus albus) to guide passage designs in the fragmented Yellowstone River

USGS Publications Warehouse

Braaten, P. J.; Elliott, Caroline M.; Rhoten, Jason C.; Fuller, D. B.; McElroy, Brandon J.

2015-01-01

Fragmentation of the Yellowstone River is hypothesized to preclude recruitment of endangered Scaphirhynchus albus (pallid sturgeon) by impeding upstream spawning migrations and access to upstream spawning areas, thereby limiting the length of free-flowing river required for survival of early life stages. Building on this hypothesis, the reach of the Yellowstone River affected by Intake Diversion Dam (IDD) is targeted for modification. Structures including a rock ramp and by-pass channel have been proposed as restoration alternatives to facilitate passage. Limited information on migrations and swimming capabilities of pallid sturgeon is available to guide engineering design specifications for the proposed structures. Migration behavior, pathways (channel routes used during migrations), and swimming capabilities of free-ranging wild adult pallid sturgeon were examined using radiotelemetry, and complemented with hydraulic data obtained along the migration pathways. Migrations of 12–26% of the telemetered pallid sturgeon population persisted to IDD, but upstream passage over the dam was not detected. Observed migration pathways occurred primarily through main channel habitats; however, migrations through side channels up to 3.9 km in length were documented. The majority of pallid sturgeon used depths of 2.2–3.4 m and mean water velocities of 0.89–1.83 m/s while migrating. Results provide inferences on depths, velocities, and habitat heterogeneity of reaches successfully negotiated by pallid sturgeon that may be used to guide designs for structures facilitating passage at IDD. Passage will provide connectivity to potential upstream spawning areas on the Yellowstone River, thereby increasing the likelihood of recruitment for this endangered species.

Wild, scenic, and transcendental rivers

NASA Astrophysics Data System (ADS)

Showstack, Randy

“A more lovely stream than this has never flowed on Earth,” 19th century American author Nathaniel Hawthorne wrote about the confluence of the Assabet and Concord Rivers, streams that meander about 40 km west of Boston, Massachusetts.Segments of these streams as well as the Assabet River became the newest additions to the U.S. National Wild and Scenic Rivers System, when President Bill Clinton signed into law the “Sudbury, Assabet, and Concord Wild and Scenic River Act” on April 9.

Employing the Hilbert-Huang Transform to analyze observed natural complex signals: Calm wind meandering cases

NASA Astrophysics Data System (ADS)

Martins, Luis Gustavo Nogueira; Stefanello, Michel Baptistella; Degrazia, Gervásio Annes; Acevedo, Otávio Costa; Puhales, Franciano Scremin; Demarco, Giuliano; Mortarini, Luca; Anfossi, Domenico; Roberti, Débora Regina; Costa, Felipe Denardin; Maldaner, Silvana

2016-11-01

In this study we analyze natural complex signals employing the Hilbert-Huang spectral analysis. Specifically, low wind meandering meteorological data are decomposed into turbulent and non turbulent components. These non turbulent movements, responsible for the absence of a preferential direction of the horizontal wind, provoke negative lobes in the meandering autocorrelation functions. The meandering characteristic time scales (meandering periods) are determined from the spectral peak provided by the Hilbert-Huang marginal spectrum. The magnitudes of the temperature and horizontal wind meandering period obtained agree with the results found from the best fit of the heuristic meandering autocorrelation functions. Therefore, the new method represents a new procedure to evaluate meandering periods that does not employ mathematical expressions to represent observed meandering autocorrelation functions.

Sex-biased survivorship and differences in migration of wild steelhead (Oncorhynchus mykiss) smolts from two coastal Oregon rivers

USGS Publications Warehouse

Thompson, Neil F.; Leblanc, Camille A.; Romer, Jeremy D.; Schreck, Carl B.; Blouin, Michael S.; Noakes, David L. G.

2016-01-01

In salmonids with partial migration, females are more likely than males to undergo smoltification and migrate to the ocean (vs. maturing in freshwater). However, it is not known whether sex affects survivorship during smolt migration (from fresh water to entry into the ocean). We captured wild steelhead (Oncorhynchus mykiss) smolts in two coastal Oregon rivers (USA) and collected fin tissue samples for genetic sex determination (2009; N = 70 in the Alsea and N = 69 in the Nehalem, 2010; N = 25 in the Alsea). We implanted acoustic tags and monitored downstream migration and survival until entry in to the Pacific Ocean. Survival was defined as detection at an estuary/ocean transition array. We found no effect of sex on smolt survivorship in the Nehalem River in 2009, or in the Alsea River in 2010. However, males exhibited significantly lower survival than females in the Alsea River during 2009. Residency did not influence this result as an equal proportion of males and females did not reach the estuary entrance (11% of males, 9% of females). The sexes did not differ in timing or duration of migration, so those variables seem unlikely to explain sex-biased survivorship. Larger males had higher odds of survival than smaller males in 2009, but the body size of females did not affect survivorship. The difference in survivorship between years in the Alsea River could be due to flow conditions, which were higher in 2010 than in 2009. Our findings suggest that sex may affect steelhead smolt survival during migration, but that the difference in survivorship may be weak and not a strong factor influencing adult sex ratios.

Sex biased survival and differences in migration of wild steelhead (Oncorhynchus mykiss) smolts from two coastal Oregon rivers

USGS Publications Warehouse

Thompson, Neil F.; Leblanc, Camille A.; Romer, Jeremy D.; Schreck, Carl B.; Blouin, Michael S.; Noakes, David L. G.

2016-01-01

In salmonids with partial migration, females are more likely than males to undergo smoltification and migrate to the ocean (vs. maturing in freshwater). However, it is not known whether sex affects survivorship during smolt migration (from fresh water to entry into the ocean). We captured wild steelhead (Oncorhynchus mykiss) smolts in two coastal Oregon rivers (USA) and collected fin tissue samples for genetic sex determination (2009; N = 70 in the Alsea and N = 69 in the Nehalem, 2010; N = 25 in the Alsea). We implanted acoustic tags and monitored downstream migration and survival until entry in to the Pacific Ocean. Survival was defined as detection at an estuary/ocean transition array. We found no effect of sex on smolt survivorship in the Nehalem River in 2009, or in the Alsea River in 2010. However, males exhibited significantly lower survival than females in the Alsea River during 2009. Residency did not influence this result as an equal proportion of males and females did not reach the estuary entrance (11% of males, 9% of females). The sexes did not differ in timing or duration of migration, so those variables seem unlikely to explain sex-biased survivorship. Larger males had higher odds of survival than smaller males in 2009, but the body size of females did not affect survivorship. The difference in survivorship between years in the Alsea River could be due to flow conditions, which were higher in 2010 than in 2009. Our findings suggest that sex may affect steelhead smolt survival during migration, but that the difference in survivorship may be weak and not a strong factor influencing adult sex ratios.

On the characteristics and scales of outer bank roughness on large meander bends: the influence of bank material properties, floodplain vegetation and flow inundation

USDA-ARS?s Scientific Manuscript database

This paper explores the scales and characteristics of form roughness along the outer banks of two bends on a large meandering river through investigation of irregularities in bank contours and local topographic variability on the bank face. The analysis also examines how roughness varies over the ve...

WATER QUALITY STATUS REPORT, CROOKED RIVER, IDAHO COUNTY IDAHO, 1987

EPA Science Inventory

Crooked River (17060305), a primary anadromous fisheries resource, is located approximately 120 miles southeast of Lewiston, Idaho. Dredging operations between 1936 and 1948 left large piles of gravel in the natural watercourse, causing the river to meander. Impoundments of wat...

Evaluating spawning migration patterns and predicting spawning success of shovelnose sturgeon in the Lower Missouri River

USGS Publications Warehouse

Wildhaber, M.L.; Holan, S.H.; Davis, G.M.; Gladish, D.W.; DeLonay, A.J.; Papoulias, D.M.; Sommerhauser, D.K.

2011-01-01

Approaches using telemetry, precise reproductive assessments, and surgically implanted data storage tags (DSTs) were used in combination with novel applications of analytical techniques for fish movement studies to describe patterns in migratory behavior and predict spawning success of gravid shovelnose sturgeon. From 2004 to 2007, over 300 gravid female shovelnose sturgeon (Scaphirhynchus platorynchus) from the Lower Missouri River, that were expected to spawn in the year they were collected, were surgically implanted with transmitters and archival DSTs. Functional cluster modeling of telemetry data from the spawning season suggested two common migration patterns of gravid female shovelnose sturgeon. Fish implanted from 958 to 1181 river kilometer (rkm) from the mouth of the Missouri River (or northern portion of the Lower Missouri River within 354rkm of the lowest Missouri River dam at rkm 1305) had one migration pattern. Of fish implanted from 209 to 402rkm from the mouth of the Missouri River (or southern portion of the Lower Missouri River), half demonstrated a movement pattern similar to the northern fish while the other half demonstrated a migration pattern that covered more of the river. There was no apparent difference in migration patterns between successful and unsuccessful spawners. Multiple hypotheses exist to explain differences in migratory patterns among fish from different river reaches. Additional work is required to determine if observed differences are due to multiple adapted strategies, environmental alteration, and/or initial tagging date. Hierarchical Bayesian modeling of DST data indicated that variation in depth usage patterns was consistently different between successful and unsuccessful spawners, as indicated by differences in likelihood of switching between high and low variability states. Analyses of DST data, and data collected at capture, were sufficient to predict 8 of 10 non-spawners/incomplete spawners and all 30 spawners in the

Evaluating spawning migration patterns and predicting spawning success of shovelnose sturgeon in the Lower Missouri River

USGS Publications Warehouse

Wildhaber, M.L.; Holan, S.H.; Davis, G.M.; Gladish, D.W.; DeLonay, A.J.; Papoulias, D.M.; Sommerhauser, D.K.

2011-01-01

Approaches using telemetry, precise reproductive assessments, and surgically implanted data storage tags (DSTs) were used in combination with novel applications of analytical techniques for fish movement studies to describe patterns in migratory behavior and predict spawning success of gravid shovelnose sturgeon. From 2004 to 2007, over 300 gravid female shovelnose sturgeon (Scaphirhynchus platorynchus) from the Lower Missouri River, that were expected to spawn in the year they were collected, were surgically implanted with transmitters and archival DSTs. Functional cluster modeling of telemetry data from the spawning season suggested two common migration patterns of gravid female shovelnose sturgeon. Fish implanted from 958 to 1181 river kilometer (rkm) from the mouth of the Missouri River (or northern portion of the Lower Missouri River within 354 rkm of the lowest Missouri River dam at rkm 1305) had one migration pattern. Of fish implanted from 209 to 402 rkm from the mouth of the Missouri River (or southern portion of the Lower Missouri River), half demonstrated a movement pattern similar to the northern fish while the other half demonstrated a migration pattern that covered more of the river. There was no apparent difference in migration patterns between successful and unsuccessful spawners. Multiple hypotheses exist to explain differences in migratory patterns among fish from different river reaches. Additional work is required to determine if observed differences are due to multiple adapted strategies, environmental alteration, and/or initial tagging date. Hierarchical Bayesian modeling of DST data indicated that variation in depth usage patterns was consistently different between successful and unsuccessful spawners, as indicated by differences in likelihood of switching between high and low variability states. Analyses of DST data, and data collected at capture, were sufficient to predict 8 of 10 non-spawners/incomplete spawners and all 30 spawners in the

Migration and spawning of female surubim (Pseudoplatystoma corruscans, Pimelodidae) in the São Francisco river, Brazil

USGS Publications Warehouse

Godinho, Alexandre L.; Kynard, Boyd; Godinho, Hugo P.

2007-01-01

Surubim, Pseudoplatystoma corruscans, is the most valuable commercial and recreational fish in the São Francisco River, but little is known about adult migration and spawning. Movements of 24 females (9.5–29.0 kg), which were radio-tagged just downstream of Três Marias Dam (TMD) at river kilometer 2,109 and at Pirapora Rapids (PR) 129 km downstream of TMD, suggest the following conceptual model of adult female migration and spawning. The tagged surubims used only 274 km of the main stem downstream of TMD and two tributaries, the Velhas and Abaeté rivers. Migration style was dualistic with non-migratory (resident) and migratory fish. Pre-spawning females swam at ground speeds of up to 31 km day-1 in late September–December to pre-spawning staging sites located 0–11 km from the spawning ground. In the spawning season (November–March), pre-spawning females migrated back and forth from nearby pre-spawning staging sites to PR for short visits to spawn, mostly during floods. Multiple visits to the spawning site suggest surubim is a multiple spawner. Most post-spawning surubims left the spawning ground to forage elsewhere, but some stayed at the spawning site until the next spawning season. Post-spawning migrants swam up or downstream at ground speeds up to 29 km day-1 during January–March. Construction of proposed dams in the main stem and tributaries downstream of TMD will greatly reduce surubim abundance by blocking migrations and changing the river into reservoirs that eliminate riverine spawning and non-spawning habitats, and possibly, cause extirpation of populations.

Time-Frequency Variability of Kuroshio Meanders in Tokara Strait

NASA Astrophysics Data System (ADS)

Nakamura, H.; Yamashiro, T.; Nishina, A.; Ichikawa, H.

2006-12-01

The Kuroshio path in the northern Okinawa Trough, Japan, located between the continental slope and Tokara Strait, exhibits meandering motions with largest displacements in the East China Sea; these motions have dominant periods in the broad range of 30-90 days. Understanding the dynamic nature of such meanders is crucial to predicting small and large meanders of the Kuroshio path off the south coast of Japan. Previous numerical simulations suggest that the Kuroshio path meanders in the northern Okinawa Trough become nonstationary in variance because of changes in background states of the Kuroshio in the northern Okinawa Trough, but a detailed analysis based on observed data has yet to be performed. The purpose of the present study is to provide a detailed description of the time-frequency variability of Kuroshio path meanders observed in Tokara Strait. Three Kuroshio indicators were subjected to wavelet analysis for the period 1984-2004: the Kuroshio Position Index (KPI) in Tokara Strait, Kuroshio Volume Transport (KVT) in Tokara Strait, and the basal current velocity of the Kuroshio on the continental slope in the northern Okinawa Trough. The 30-90 day variance of the KPI shows a season-fixed nature, with larger amplitudes in the period December-July. The amplitude of the variance in this phenomenon is also modulated by interannual variations, with small variance recorded during 1989-1992, large variance during 1993-1998, and a return to small variance from 1999-2003. This interannual variation is positively correlated with that of the KVT. The largest variance of the KPI during February-April precedes the largest volume transport in April-May by about 1 month, suggesting that eddy vorticity flux strengthens the mean current field. Previous numerical simulations reproduce the recirculation gyre as a cyclonic eddy in the area between the continental slope and Tokara Strait; this gyre is analogous to the northern recirculation gyre associated with the eastward jet

Migration and habitats of diadromous Danube River sturgeons in Romania: 1998-2000

USGS Publications Warehouse

Kynard, B.; Suciu, R.; Horgan, M.

2002-01-01

Upstream migrant adults of stellate sturgeon, Acipenser stellatus (10 in 1998, 43 in 1999) and Russian sturgeon, A. gueldenstaedtii (three in 1999) were captured at river km (rkm) 58-137, mostly in the spring, and tagged with acoustic tags offering a reward for return. The overharvest was revealed by tag returns (38% in 1998, 28% in 1999) and by harvest within 26 days (and before reaching spawning grounds) of the six stellate sturgeon tracked upstream. A drop-back of > 50% of the tagged sturgeon, some to the Black Sea, shows a high sensitivity to interruption of migration and capture/handling/holding. Harvesting and dropback prevented tracking of sturgeon to spawning sites. Gillnetting and tracking of stellate sturgeon showed that the autumn migration ended in early October (river temperature 16??C) and identified a likely wintering area at river km (rkm) 75-76 (St George Branch). Thus, fishery harvesting after early October captures wintering fish, not migrants. Rare shoreline cliffs in the lower river likely create the only rocky habitat for sturgeon spawning. A survey for potential spawning habitats found five sites with rocky substrate and moderate water velocity, all ???rkm 258. Drift netting caught early life-stages of 17 fish species and one sturgeon, a beluga, Huso huso, larva likely spawned at ???rkm 258. All diadromous Danube sturgeons likely spawn at ???rkm 258.

Historical perspectives on channel pattern in the Clark Fork River, Montana and implications for post-dam removal restoration

NASA Astrophysics Data System (ADS)

Woelfle-Erskine, C. A.; Wilcox, A. C.

2009-12-01

Active restoration approaches such as channel reconstruction have moved beyond the realm of small streams and are being applied to larger rivers. Uncertainties arising from limited knowledge, fluvial and ecosystem variability, and contaminants are especially significant in restoration of large rivers, where project costs and the social, infrastructural, and ecological costs of failure are high. We use the case of Milltown Dam removal on the Clark Fork River, Montana and subsequent channel reconstruction in the former reservoir to examine the use of historical research and uncertainty analysis in river restoration. At a cost of approximately $120 million, the Milltown Dam removal involves the mechanical removal of approximately 2 million cubic meters of sediments contaminated by upstream mining, followed by restoration of the former reservoir reach in which a single-thread meandering channel is being constructed. Historical maps, surveys, photographs, and accounts suggest a conceptual model of a multi-thread, anastomosing river in the reach targeted for channel reconstruction, upstream of the confluence of the Clark Fork and Blackfoot Rivers. We supplemented historical research with analysis of aerial photographs, topographic data, and USGS stage-discharge measurements in a lotic but reservoir-influenced reach of the Clark Fork River within our study area to estimate avulsion frequency (0.8 avulsions/year over a 70-year period) and average rates of lateral migration and aggradation. These were used to calculate the mobility number, a dimensionless relationship between channel filling and lateral migration timescales that can be used to predict whether a river’s planform is single or multi-threaded. The mobility number within our study reach ranged from 0.6 (multi-thread channel) to 1.7 (transitional channel). We predict that, in the absence of active channel reconstruction, the post-dam channel pattern would evolve to one that alternates between single and multi

Flood plain and channel dynamics of the Quinault and Queets Rivers, Washington, USA

USGS Publications Warehouse

O'Connor, J. E.; Jones, M.A.; Haluska, T.L.

2003-01-01

Observations from this study and previous studies on the Queets River show that channel and flood-plain dynamics and morphology are affected by interactions between flow, sediment, and standing and entrained wood, some of which likely involve time frames similar to 200–500-year flood-plain half-lives. On the upper Quinault River and Queets River, log jams promote bar growth and consequent channel shifting, short-distance avulsions, and meander cutoffs, resulting in mobile and wide active channels. On the lower Quinault River, large portions of the channel are stable and flow within vegetated flood plains. However, locally, channel-spanning log jams have caused channel avulsions within reaches that have been subsequently mobile for several decades. In all three reaches, log jams appear to be areas of conifer germination and growth that may later further influence channel and flood-plain conditions on long time scales by forming flood-plain areas resistant to channel migration and by providing key members of future log jams. Appreciation of these processes and dynamics and associated temporal and spatial scales is necessary to formulate effective long-term approaches to managing fluvial ecosystems in forested environments.

Meandering Brownian Donkeys

NASA Astrophysics Data System (ADS)

Eichhorn, R.; Reimann, P.

2004-04-01

We consider a Brownian particle whose motion is confined to a ``meandering'' pathway and which is driven away from thermal equilibrium by an alternating external force. This system exhibits absolute negative mobility, i.e. when an external static force is applied the particle moves in the direction opposite to that force. We reveal the physical mechanism behind this ``donkey-like'' behavior, and derive analytical approximations that are in excellent agreement with numerical results.

How Physical Processes are Informing River Management Actions at Marble Bluff Dam, Truckee River, Nevada

NASA Astrophysics Data System (ADS)

Bountry, J.; Godaire, J.; Bradley, D. N.

2017-12-01

At the terminus of the Truckee River into Pyramid Lake (Nevada, USA), upstream river management actions have dramatically reshaped the river landscape, posing significant challenges for the management of endangered aquatic species and maintenance of existing infrastructure. Within the last 100 years, upstream water withdrawal for human uses has resulted in a rapid lowering of Pyramid Lake which initiated up to 90 ft of channel incision. In 1976 Marble Bluff Dam was constructed to halt the upstream progression of channel incision and protect upstream agricultural lands, tribal resources, and infrastructure. Since construction an additional 40 ft of lake lowering and subsequent channel lowering now poses a potential risk to the structural integrity of the dam. The dynamic downstream river combined with ongoing reservoir sedimentation pose challenges to fish passage facilities that enable migration of numerous endangered cui-ui and threatened Lahontan Cutthroat Trout (LCT) to upstream spawning areas each year. These facilities include a fish lock at the dam, a fish bypass channel which allows fish to avoid the shallow delta area during low lake levels, and a meandering channel constructed by the Nature Conservancy to connect the bypass channel to the receding Pyramid Lake. The reservoir formed by Marble Bluff Dam has completely filled with sediment which impacts fish passage facilities. The original operating manual for the dam recommends year-round flushing of sediment through radial gates, but this can no longer be accomplished. During critical fish migration periods in the spring operators must ensure fish entrance channels downstream of the dam are not buried with released sediment and fish are not trapped in a portion of the reservoir full of sediment that would risk sending them back over the dam. To help inform future reservoir sediment and infrastructure management strategies, we bracket a range of potential river responses to lake level lowering and floods

Assessment of the effects of regional channel stability and sediment transport on roadway hydraulic structures : final report.

DOT National Transportation Integrated Search

2014-06-01

Rivers and streams evolve all the time. As a result, no stream channel is absolutely stable. Channels evolve at various speeds both vertically (degradation/aggradation) and horizontally (meander : migration). They also respond to man-made changes ran...

Rotor meandering contributes to irregularity in electrograms during atrial fibrillation.

PubMed

Zlochiver, Sharon; Yamazaki, Masatoshi; Kalifa, Jérôme; Berenfeld, Omer

2008-06-01

Radiofrequency ablation therapy of atrial fibrillation (AF) recently incorporated the analysis of dominant frequency (DF) and/or electrogram fractionation for guidance. However, the relationships between DF, fractionation, and spatiotemporal characteristics of the AF source remain unclear. We hypothesize that a meandering reentrant AF source contributes to the wave fractionation and is reflected in the power spectrum of local electrograms elsewhere in the rotor's surroundings. Meandering rotors as AF sources were simulated in 2-dimensional models of human atrial tissue and recorded in isolated sheep hearts. Nondominant elements of the signals were differentiated from the dominant elements using singular value decomposition, whereby the purely periodic constituent (PC) relating to the rotor's DF was eliminated rendering a residual constituent (RC) that consisted of all other activity. Spectral analysis of the decomposed constituents revealed peaks corresponding to the meandering frequency of the rotor tip, the magnitudes of which were proportional to the size of and the distance to the rotor core. Similar analyses on epicardial optical signals and electrograms from isolated sheep hearts, as well as human complex fractionated atrial electrograms, showed applicability of the approach. Increased meandering of the rotor driving AF reduces activation periodicity and increases fractionation. The spectral manifestation of the rotor activity beyond the meandering region makes it possible to characterize AF source stability, as well as DF in humans using electrode mapping.

Meandering instability of a viscous thread

NASA Astrophysics Data System (ADS)

Morris, Stephen W.; Dawes, Jonathan H. P.; Ribe, Neil M.; Lister, John R.

2008-06-01

A viscous thread falling from a nozzle onto a surface exhibits the famous rope-coiling effect, in which the thread buckles to form loops. If the surface is replaced by a belt moving with speed U , the rotational symmetry of the buckling instability is broken and a wealth of interesting states are observed [see S. Chiu-Webster and J. R. Lister, J. Fluid Mech. 569, 89 (2006)]. We experimentally studied this “fluid-mechanical sewing machine” in a more precise apparatus. As U is reduced, the steady catenary thread bifurcates into a meandering state in which the thread displacements are only transverse to the motion of the belt. We measured the amplitude and frequency ω of the meandering close to the bifurcation. For smaller U , single-frequency meandering bifurcates to a two-frequency “figure-8” state, which contains a significant 2ω component and parallel as well as transverse displacements. This eventually reverts to single-frequency coiling at still smaller U . More complex, highly hysteretic states with additional frequencies are observed for larger nozzle heights. We propose to understand this zoology in terms of the generic amplitude equations appropriate for resonant interactions between two oscillatory modes with frequencies ω and 2ω . The form of the amplitude equations captures both the axisymmetry of the U=0 coiling state and the symmetry-breaking effects induced by the moving belt.

Meandering instability of a viscous thread.

PubMed

Morris, Stephen W; Dawes, Jonathan H P; Ribe, Neil M; Lister, John R

2008-06-01

A viscous thread falling from a nozzle onto a surface exhibits the famous rope-coiling effect, in which the thread buckles to form loops. If the surface is replaced by a belt moving with speed U , the rotational symmetry of the buckling instability is broken and a wealth of interesting states are observed [see S. Chiu-Webster and J. R. Lister, J. Fluid Mech. 569, 89 (2006)]. We experimentally studied this "fluid-mechanical sewing machine" in a more precise apparatus. As U is reduced, the steady catenary thread bifurcates into a meandering state in which the thread displacements are only transverse to the motion of the belt. We measured the amplitude and frequency omega of the meandering close to the bifurcation. For smaller U , single-frequency meandering bifurcates to a two-frequency "figure-8" state, which contains a significant 2omega component and parallel as well as transverse displacements. This eventually reverts to single-frequency coiling at still smaller U . More complex, highly hysteretic states with additional frequencies are observed for larger nozzle heights. We propose to understand this zoology in terms of the generic amplitude equations appropriate for resonant interactions between two oscillatory modes with frequencies omega and 2omega . The form of the amplitude equations captures both the axisymmetry of the U=0 coiling state and the symmetry-breaking effects induced by the moving belt.

Comparison of Cottonwood Dendrochronology and Optically Stimulated Luminescence Geochronometers Along a High Plains Meandering River, Powder River, Montana, USA

NASA Astrophysics Data System (ADS)

Hasse, T. R.; Schook, D. M.

2017-12-01

Geochronometers at centennial scales can aid our understanding of process rates in fluvial geomorphology. Plains cottonwood trees (Populus deltoides ssp. Monilifera) in the high plains of the United States are known to germinate on freshly created deposits such as point bars adjacent to rivers. As the trees mature they may be partially buried (up to a few meters) by additional flood deposits. Cottonwood age gives a minimum age estimate of the stratigraphic surface where the tree germinated and a maximum age estimate for overlying sediments, providing quantitative data on rates of river migration and sediment accumulation. Optically Stimulated Luminescence (OSL) of sand grains can be used to estimate the time since the sand grains were last exposed to sunlight, also giving a minimum age estimate of sediment burial. Both methods have disadvantages: Browsing, partial burial, and other damage to young cottonwoods can increase the time required for the tree to reach a height where it can be sampled with a tree corer, making the germination point a few years to a few decades older than the measured tree age; fluvial OSL samples can have inherited age (when the OSL age is older than the burial age) if the sediment was not completely bleached prior to burial. We collected OSL samples at 8 eroding banks of the Powder River Montana, and tree cores at breast height (±1.2 m) from cottonwood trees growing on the floodplain adjacent to the OSL sample locations. Using the Minimum Age Model (MAM) we found that OSL ages appear to be 500 to 1,000 years older than the adjacent cottonwood trees which range in age (at breast height) from 60 to 185 years. Three explanations for this apparent anomaly in ages are explored. Samples for OSL could be below a stratigraphic unconformity relative to the cottonwood germination elevation. Shallow samples for OSL could be affected by anthropogenic mixing of sediments due to plowing and leveling of hay fields. The OSL samples could have

Recent (circa 1998 to 2011) channel-migration rates of selected streams in Indiana

USGS Publications Warehouse

Robinson, Bret A.

2013-01-01

An investigation was completed to document recent (circa 1998 to 2011) channel-migration rates at 970 meander bends along 38 of the largest streams in Indiana. Data collection was completed by using the Google Earth™ platform and, for each selected site, identifying two images with capture dates separated by multiple years. Within each image, the position of the meander-bend cutbank was measured relative to a fixed local landscape feature visible in both images, and an average channel-migration rate was calculated at the point of maximum cutbank displacement. From these data it was determined that 65 percent of the measured sites have recently been migrating at a rate less than 1 ft/yr, 75 percent of the sites have been migrating at a rate less than 10 ft/yr, and while some sites are migrating in excess of 20 ft/yr, these occurrences are rare. In addition, it is shown that recent channel-migration activity is not evenly distributed across Indiana. For the stream reaches studied, far northern and much of far southern Indiana are drained by streams that recently have been relatively stationary. At the same time, this study shows that most of the largest streams in west-central Indiana and many of the largest streams in east-central Indiana have shown significant channel-migration activity during the recent past. It is anticipated that these results will support several fluvial-erosion-hazard mitigation activities currently being undertaken in Indiana.

Rotor Meandering Contributes to Irregularity in Electrograms during Atrial Fibrillation

PubMed Central

Zlochiver, Sharon; Yamazaki, Masatoshi; Kalifa, Jerome; Berenfeld, Omer

2010-01-01

Radiofrequency ablation therapy of atrial fibrillation (AF) recently incorporated the analysis of dominant frequency (DF) and/or electrogram fractionation for guidance. However, the relationships between DF, fractionation and spatio-temporal characteristics of the AF source remain unclear. We hypothesize that meandering reentrant AF source contributes to the wave fractionation and is reflected in the power spectrum of local electrograms elsewhere in the rotor’s surroundings. Methods Meandering rotors as AF sources were simulated in 2D models of human atrial tissue and recorded in isolated sheep hearts. Non-dominant elements of the signals were differentiated from the dominant elements using singular value decomposition, whereby the purely periodic constituent (PC) relating to the rotor’s DF was eliminated rendering a residual constituent (RC) that consisted of all other activity. Results Spectral analysis of the decomposed constituents revealed peaks corresponding to the meandering frequency of the rotor tip, the magnitudes of which were proportional to the size of, and the distance to the rotor core. Similar analyses on epicardial optical signals and electrograms from isolated sheep hearts, as well as human complex fractionated atrial electrograms demonstrated applicability of the approach. Conclusion Increased meandering of the rotor driving AF reduces activation periodicity and increases fractionation. The spectral manifestation of the rotor activity beyond the meandering region makes it possible to characterize AF source stability, as well as DF in humans using electrode mapping. PMID:18534369

Channel adjustments to historical disturbances along the lower Brazos and Sabine Rivers, south-central USA

NASA Astrophysics Data System (ADS)

Heitmuller, Franklin T.

2014-01-01

Historical channel adjustments are documented and discussed in context with anthropogenic disturbances along two meandering, coastal plain rivers - the lower Brazos and Sabine Rivers in the south-central United States. Hard-copy streamflow-measurement notes of the U.S. Geological Survey were utilized to render historical cross sections (1925-2007) at nine gauging stations, which were complemented with repeat photographs and flood-frequency analysis to assess trajectories of channel change and interpret causative mechanisms. Downstream- and upstream-propagating disturbances caused episodes of channel-bed incision and aggradation at different locations for distinct time periods along both rivers. Incision associated with upstream dams is detected, but channels are compensated downstream with sediment inputs from lateral channel migration and tributaries. In one case, temporary aggradation along the Brazos River at Waco was likely caused by a combination of dam construction and regional soil erosion. Channel-bed incision on the lowermost Brazos River is unrelated to dams, but is associated with instream aggregate extraction, possibly in conjunction with downstream channelization. On the Sabine River, extensive aggradation during the 1930s might be associated with logging activities (1880s-1930s), but whether the cause is pervasive regional-scale hillslope erosion or local-scale mill-site activities is indeterminate. Following passage of this sediment, the river generally recovered to pre-disturbance conditions and has exhibited stability despite a mainstem reservoir. Translation of this sediment slug is attenuated by a transition to a flood-prone, distributary-dominated system downstream of the Holocene-Pleistocene terrace onlap position. Additional findings include cross-channel hingepoints separating thalweg incision from simultaneous point-bar or bank accretion at meander bends, which indicates channel adjustment occurs along non-cohesive beds in preference to

Effect of nacelle on wake meandering in a laboratory scale wind turbine using LES

NASA Astrophysics Data System (ADS)

Foti, Daniel; Yang, Xiaolei; Guala, Michele; Sotiropoulos, Fotis

2015-11-01

Wake meandering, large scale motion in the wind turbine wakes, has considerable effects on the velocity deficit and turbulence intensity in the turbine wake from the laboratory scale to utility scale wind turbines. In the dynamic wake meandering model, the wake meandering is assumed to be caused by large-scale atmospheric turbulence. On the other hand, Kang et al. (J. Fluid Mech., 2014) demonstrated that the nacelle geometry has a significant effect on the wake meandering of a hydrokinetic turbine, through the interaction of the inner wake of the nacelle vortex with the outer wake of the tip vortices. In this work, the significance of the nacelle on the wake meandering of a miniature wind turbine previously used in experiments (Howard et al., Phys. Fluid, 2015) is demonstrated with large eddy simulations (LES) using immersed boundary method with fine enough grids to resolve the turbine geometric characteristics. The three dimensionality of the wake meandering is analyzed in detail through turbulent spectra and meander reconstruction. The computed flow fields exhibit wake dynamics similar to those observed in the wind tunnel experiments and are analyzed to shed new light into the role of the energetic nacelle vortex on wake meandering. This work was supported by Department of Energy DOE (DE-EE0002980, DE-EE0005482 and DE-AC04-94AL85000), and Sandia National Laboratories. Computational resources were provided by Sandia National Laboratories and the University of Minnesota Supercomputing.

Gulf sturgeon spawning migration and habitat in the Choctawhatchee River system, Alabama-Florida

USGS Publications Warehouse

Fox, D.A.; Hightower, J.E.; Parauka, F.M.

2000-01-01

Information about spawning migration and spawning habitat is essential to maintain and ultimately restore populations of endangered and threatened species of anadromous fish. We used ultrasonic and radiotelemetry to monitor the movements of 35 adult Gulf sturgeon Acipenser oxyrinchus desotoi (a subspecies of the Atlantic sturgeon A. oxyrinchus) as they moved between Choctawhatchee Bay and the Choctawhatchee River system during the spring of 1996 and 1997. Histological analysis of gonadal biopsies was used to determine the sex and reproductive status of individuals. Telemetry results and egg sampling were used to identify Gulf sturgeon spawning sites and to examine the roles that sex and reproductive status play in migratory behavior. Fertilized Gulf sturgeon eggs were collected in six locations in both the upper Choctawhatchee and Pea rivers. Hard bottom substrate, steep banks, and relatively high flows characterized collection sites. Ripe Gulf sturgeon occupied these spawning areas from late March through early May, which included the interval when Gulf sturgeon eggs were collected. For both sexes, ripe fish entered the Choctawhatchee River significantly earlier and at a lower water temperature and migrated further upstream than did nonripe fish. Males entered the Choctawhatchee River at a lower water temperature than females. Results from histology and telemetry support the hypothesis that male Gulf sturgeon may spawn annually, whereas females require more than 1 year between spawning events. Upper river hard bottom areas appear important for the successful spawning of Gulf sturgeon, and care should be taken to protect against habitat loss or degradation of known spawning habitat.

27 CFR 9.200 - Mokelumne River.

Code of Federal Regulations, 2011 CFR

2011-04-01

... significance. (b) Approved maps. The seven United States Geological Survey, 1:24,000 scale, topographic... South, Calif., 1968, photorevised 1976; (2) Terminous, Calif., 1978, minor revision 1993; (3) Thornton... Quadrangle); then (2) Proceed southeast (upstream) 5 miles along the meandering Mokelumne River to its...

27 CFR 9.200 - Mokelumne River.

Code of Federal Regulations, 2010 CFR

2010-04-01

... significance. (b) Approved maps. The seven United States Geological Survey, 1:24,000 scale, topographic... South, Calif., 1968, photorevised 1976; (2) Terminous, Calif., 1978, minor revision 1993; (3) Thornton... Quadrangle); then (2) Proceed southeast (upstream) 5 miles along the meandering Mokelumne River to its...

General mechanism for the meandering instability of rivulets of Newtonian fluids.

PubMed

Daerr, A; Eggers, J; Limat, L; Valade, N

2011-05-06

A rivulet flowing down an inclined plane often does not follow a straight path, but starts to meander spontaneously. Here we show that this instability is the result of two key ingredients: fluid inertia and anisotropy of the friction between rivulet and substrate. Meandering only occurs if the motion normal to the instantaneous flow direction is more difficult than parallel to it. We give a quantitative criterion for the onset of meandering and confirm it by comparing to the flow of a rivulet between two glass plates which are wetted completely. Above the threshold, the rivulet follows an irregular pattern with a typical wavelength of a few cm.

The influence of tributary flow density differences on the hydrodynamic behavior of a confluent meander bend and implications for flow mixing

NASA Astrophysics Data System (ADS)

Herrero, Horacio S.; Díaz Lozada, José M.; García, Carlos M.; Szupiany, Ricardo N.; Best, Jim; Pagot, Mariana

2018-03-01

The goal of this study is to evaluate the influence of tributary flow density differences on hydrodynamics and mixing at a confluent meander bend. A detailed field characterization is performed using an Acoustic Doppler Current Profiler (ADCP) for quantification of the 3D flow field, flow discharge and bathymetry, as well as CTD measurements (conductivity, temperature, depth) to characterize the patterns of mixing. Satellite images of the confluence taken at complementary times to the field surveys were analyzed to evaluate the confluence hydrodynamics at different flow conditions. The results illustrate the differences in hydrodynamics and mixing length in relation to confluences with equal density tributaries. At low-density differences, and higher discharge ratio (Qr) between the two rivers, the flow is similar to equi-density confluent meander bends. In contrast, at high-density differences (low Qr), the tributary flow is confined to near the confluence but the density difference causes the flow to move across channel. In this case, the density difference causes the lateral spread of the tributary flow to be greater than at a greater Qr when the density difference is less. These results illustrate the potential importance of density differences between tributaries in determining the rate and spatial extent of mixing and sediment dispersal at confluent meander bends.

Meandering worms: mechanics of undulatory burrowing in muds

PubMed Central

Dorgan, Kelly M.; Law, Chris J.; Rouse, Greg W.

2013-01-01

Recent work has shown that muddy sediments are elastic solids through which animals extend burrows by fracture, whereas non-cohesive granular sands fluidize around some burrowers. These different mechanical responses are reflected in the morphologies and behaviours of their respective inhabitants. However, Armandia brevis, a mud-burrowing opheliid polychaete, lacks an expansible anterior consistent with fracturing mud, and instead uses undulatory movements similar to those of sandfish lizards that fluidize desert sands. Here, we show that A. brevis neither fractures nor fluidizes sediments, but instead uses a third mechanism, plastically rearranging sediment grains to create a burrow. The curvature of the undulating body fits meander geometry used to describe rivers, and changes in curvature driven by muscle contraction are similar for swimming and burrowing worms, indicating that the same gait is used in both sediments and water. Large calculated friction forces for undulatory burrowers suggest that sediment mechanics affect undulatory and peristaltic burrowers differently; undulatory burrowing may be more effective for small worms that live in sediments not compacted or cohesive enough to extend burrows by fracture. PMID:23446526

Reproductive indices in natural nests of giant Amazon river turtles Podocnemis expansa (Schweigger, 1812) (Testudines, Podocnemididae) in the Environmental Protection Area Meanders of the Araguaia River.

PubMed

Alves-Júnior, J R F; Lustosa, A P G; Bosso, A C S; Balestra, R A M; Bastos, L F; Miranda, L B; Santos, A L Q

2012-02-01

A count was made of unhatched eggs and hatchling live and dead Podocnemis expansa turtles in 327 natural nests located on the beaches of the Environmental Protection Area (EPA) Meanders of the Araguaia River, to determine the percentage of hatching (94.63%), non-hatching (5.37%), survival (94.24%) and hatchling mortality (5.76%), and the average percentage of dead hatchlings during the 15 days in the nursery (0.97%). The mean number of hatchlings per nest was determined from the sum of the number of live and dead hatchlings divided by the total number of nests, while the mean number of eggs per nest was determined from the sum of live and dead hatchlings and unhatched eggs divided by the number of nests. These calculations yielded the following mean values: live hatchlings (88.98 ± 23.94), dead hatchlings (0.37 ± 0.93), unhatched eggs (5.07 ± 9.57), and total number of eggs (94.42 ± 21.30). The reproductive efficiency of the wild population of P. expansa can be affected by many environmental factors such as temperature, humidity and rainfall. In addition, man-made factors like the presence of chemicals in the water and the potential for infectious disease also have significant impact. The reproductive indices data obtained from this study are indispensable for future investigations of hatching anomalies.

Dynamics of floodplain lakes in the Upper Amazon Basin during the late Holocene

NASA Astrophysics Data System (ADS)

Quintana-Cobo, Isabel; Moreira-Turcq, Patricia; Cordeiro, Renato C.; Aniceto, Keila; Crave, Alain; Fraizy, Pascal; Moreira, Luciane S.; Duarte Contrera, Julia Maria de Aguiar; Turcq, Bruno

2018-01-01

To better understand the impact of channel migration processes and climate change on the depositional dynamics of floodplain lakes of the upper Amazon Basin during the late Holocene, we collected three sediment cores from floodplain lakes of the Ucayali River and one from the Marañón River. The cores were dated with 14C, radiographed and described. Bulk density, grain size analysis and total organic carbon (TOC) were determined. The results show that sedimentation in Ucayali floodplain lakes was marked by variations during the late Holocene, with periods of intense hydrodynamic energy and abrupt accumulations, a gap in the record between about 2870 and 690 cal yr BP, and periods of more lacustrine conditions. These changes in sedimentation were associated with variations in the river's influence related to changes in its meandering course (2870 cal yr BP) and a period of severe flooding between 3550 and 3000 cal yr BP. Lake Lagarto on the Marañón River floodplain exhibits a different sedimentary environment of low hydrodynamics with palm trees and macrophytes. Apparently, the lake has not experienced intense migration processes during the last 600 cal yr BP (base of the core). Nevertheless, the river sediment flux to the lake was important from 600 to 500 cal yr BP, although it decreased thereafter until the present. This decrease in the mineral accumulation rate indicates a decrease in river discharge since 500 cal yr BP, which coincides with precipitation records from the central Andes. In the upper part of the three Ucayali floodplain cores, a 30- to 250-cm-thick layer of reworked sediments has been deposited since 1950 AD (post-bomb). In Lake Carmen, this layer is associated with invasion of the lake by the levee of a migrating meander of the Ucayali. In Lakes Hubos and La Moringa, however, the river is still far away and the deposition must be interpreted as the result of extreme flooding. The beginning of the Ucayali meander migration is dated back to

Quantifying the Geomorphic Dynamics of the Extensively Impacted Lower Yuba River

NASA Astrophysics Data System (ADS)

Wyrick, J. R.; Pasternack, G. B.; Carley, J. K.; Barker, R.; Massa, D.; Bratovich, P.; Reedy, G.; Johnson, T.

2010-12-01

potential for significant morphological adjustment since ~1950 on the basis of visual indicators and aerial photos. To conduct a quantitative analysis, two raster DEMs of the entire LYR from a decade apart were differenced with a method accounting for uncertainty. Then the resulting spatial pattern of high-confidence erosion and deposition were analyzed by stratifying the river according to different “masks”, such as morphological unit types, reaches, and process domains. Overall, the most conservative account indicated that there was 3,887,384 m3 of cut and 3,758,810 m3 of fill, yielding a net export of 128,574 m3. Alignment of the DEM difference results with historical aerial photos and 2D model simulations revealed the relative roles of different processes in the river, such as meander migration, kickpoint migration, and non-meander bank erosion. After 68 years of post-dam blockage of hydraulic mining influx, the LYR is still highly dynamic and adjusting. The results of this study are being used to guide diverse river management and rehabilitation actions.

Stock-specific migration timing of adult spring-summer Chinook salmon in the Columbia River basin

USGS Publications Warehouse

Keefer, M.L.; Peery, C.A.; Jepson, M.A.; Tolotti, K.R.; Bjornn, T.C.; Stuehrenberg, L.C.

2004-01-01

An understanding of the migration timing patterns of Pacific salmon Oncorhynchus spp. and steelhead O. mykiss is important for managing complex mixed-stock fisheries and preserving genetic and life history diversity. We examined adult return timing for 3,317 radio-tagged fish from 38 stocks of Columbia River basin spring-summer Chinook salmon O. tshawytscha over 5 years. Stock composition varied widely within and between years depending on the strength of influential populations. Most individual stocks migrated at similar times each year relative to overall runs, supporting the hypotheses that run timing is predictable, is at least partially due to genetic adaptation, and can be used to differentiate between some conspecific populations. Arrival timing of both aggregated radio-tagged stocks and annual runs was strongly correlated with river discharge; stocks arrived earlier at Bonneville Dam and at upstream dams in years with low discharge. Migration timing analyses identified many between-stock and between-year differences in anadromous salmonid return behavior and should and managers interested in protection and recovery of evolutionary significant populations.

A geomorphological characterisation of river systems in South Africa: A case study of the Sabie River

NASA Astrophysics Data System (ADS)

Eze, Peter N.; Knight, Jasper

2018-06-01

Fluvial geomorphology affects river character, behaviour, evolution, trajectory of change and recovery potential, and as such affects biophysical interactions within a catchment. Water bodies in South Africa, in common with many other water-stressed parts of the world, are generally under threat due to increasing natural and anthropogenic influences including aridity, siltation and pollution, as well as climate and environmental change. This study reports on a case study to characterise the geomorphology of different river systems in South Africa, with the aim of better understanding their properties, controls, and implications for biophysical interactions including water quality, biodiversity (aquatic and riparian), and human activity within the catchment. The approach adopted is based on the River Styles® framework (RSF), a geomorphology-based approach developed for rivers in New Zealand and Australia, but applied here for the first time to South Africa. Based on analysis of remote sensing imagery, SRTM-2 digital topographic data and field observations on sites through the entire river system, six geomorphic elements were identified along the Sabie River, northeast South Africa (gorge, bedrock-forced meander, low-moderate sinuosity planform controlled sand bed, meandering sand bed, low sinuosity fine grained sand bed, and floodouts), using the RSF classification scheme and based on the RSF procedural tree of Brierley and Fryirs (2005). Previous geomorphological studies along the Sabie River have shown that different reaches respond differently to episodic floods; we use these data to link river geomorphological character (as defined by the RSF) to the hydrodynamic conditions and processes giving rise to such character. This RSF approach can be used to develop a new management approach for river systems that considers their functional biophysical behaviour within individual reaches, rather than considering them as homogeneous and uniform systems.

Natural change and human impact in a present-day fluvial catchment: The Geul River, Southern Netherlands

NASA Astrophysics Data System (ADS)

Vandenberghe, J.; de Moor, J. J. W.; Spanjaard, G.

2012-07-01

The Geul River has a long history of channel straightening and bank protection, but also has several natural meandering parts. In addition, some formerly 'fixed' or 'protected' stretches of the river have been allowed to meander freely since 1988. Therefore, it represents an ideal case for evaluating the contribution of human interference to the intrinsic evolution of the river. In this paper, we compare the response of selected (not protected) reaches of the present-day river to different human modifications. The river banks were labelled as "stable", "unstable" or "erosive". As might be expected, stretches with a high sinuosity have a high percentage of erosive and unstable bank length, while low-sinuosity stretches experience hardly any erosion. The amount of lateral erosion and sedimentation in natural situations is compared with that in situations with different bank protection and stabilization types. Erosion rates may locally attain up to 2 m per year. Detailed grain-size analysis of point-bar sections enable distinction of successive fining-up sequences. Vertical aggradation rates within the point-bars are up to 0.15 m yr- 1. The highest rates are found in the youngest point-bars. Collectively, the results of this study show that when bank protection is removed, the freely meandering river creates its own specific ecosystems and retention capacity increases. Such a return to natural environmental and ecological conditions is in accordance with the objectives of the European Water Framework Directive.

Channel Stability and Water Quality of the Alagnak River, Southwestern Alaska

USGS Publications Warehouse

Curran, Janet H.

2003-01-01

The Alagnak River, a National Wild River located in southwestern Alaska, drains an area of 3,600 square kilometers and is used for recreational and subsistence activities, primarily angling, camping, rafting, and hunting by visitors and seasonal residents, and for commercial guiding by several lodges. Increases in visitor use in the 1990s included an increase in the use of high-horsepower motorboats on the river, primarily for angling, and raised concerns regarding human impacts on water quality. Downstream from its confluence with the Nonvianuk River at river kilometer (RK) 93, the Alagnak River is formed in glacial drift and outwash with a single, low bedrock outcrop. Analysis of aerial photography from 1951, 1982, and 2001 shows that the river's multiple channels from RK 57 to 93 have been relatively stable. In contrast, long reaches of multiple channels from RK 35 to 57 changed substantially between 1951 and 1982, creating a new complex of channels. Downstream from RK 35, channel changes in the past 50 years consist largely of minor meander migration. Analysis of water samples collected during this study at RK 21, 46, and 93 and in the Alagnak and Nonvianuk Rivers at the outlets of the lakes that form their source shows that the Alagnak River is a nutrient-poor, calcium-bicarbonate water with low suspended-sediment concentrations. Water chemistry changes little over time or in a downstream direction. Weak patterns over time include high late May/early June concentrations of some nutrients, carbon, and iron. Weak patterns over distance include downstream increases in iron, manganese, and phosphorous. No pervasive human impacts on Alagnak River water chemistry were detected. Local effects that could be diluted within a kilometer downstream of the source were not detectable by this study. Data collected at three continuously recording wake gaging stations at RK 21, 46, and 93 showed that 1999-2000 motorboat use was heaviest in the lower reaches of the river

Dendrogeochronologic and Anatomic Analysis of Excavated Plains Cottonwoods Determine Overbank Sedimentation Rates and Historical Channel Positions Along the Interior of a Migrating Meander Bend, Powder River, Montana

NASA Astrophysics Data System (ADS)

Metzger, T. L.; Pizzuto, J. E.; Schook, D. M.; Hasse, T. R.; Affinito, R. A.

2017-12-01

Dendrochronological dating of buried trees precisely determines the germination year and identifies the stratigraphic context of germination for the trees. This recently developed application of dendrochronology provides accurate time-averaged sedimentation rates of overbank deposition along floodplains and can be used to identify burial events. Previous studies have demonstrated that tamarisk (Tamarix ramosissima) and sandbar willow (Salix exigua) develop anatomical changes within the tree rings (increased vessel size and decreased ring widths) on burial, but observations of plains cottonwood (Populus deltoides ssp. monilifera) are lacking. In September 2016 and June 2017, five buried plains cottonwoods were excavated along a single transect of the interior of a meander bend of the Powder River, Montana. Sediment samples were obtained near each tree for 210Pb and 137Cs dating, which will allow for comparison between dendrochronological and isotopic dating methods. The plains cottonwood samples collected exhibit anatomical changes associated with burial events that are observed in other species. All trees germinated at the boundary between thinly bedded fine sand and mud and coarse sand underlain by sand and gravel, indicating plains cottonwoods germinate on top of point bars prior to overbank deposition. The precise germination age and depth provide elevations and minimum age constraints for the point bar deposits and maximum ages for the overlying sediment, helping constrain past channel positions and overbank deposition rates. Germination years of the excavated trees, estimated from cores taken 1.5 m above ground level, range from 2014 to 1862. Accurate establishment years determined by cross-dating the buried section of the tree can add an additional 10 years to the cored age. The sedimentation rate and accumulation thickness varied with tree age. The germination year, total sediment accumulation, and average sedimentation rate at the five sampled trees is

Physiological and molecular endocrine changes in maturing wild sockeye salmon, Oncorhynchus nerka, during ocean and river migration.

PubMed

Flores, A M; Shrimpton, J M; Patterson, D A; Hills, J A; Cooke, S J; Yada, T; Moriyama, S; Hinch, S G; Farrell, A P

2012-01-01

Maturing adult sockeye salmon Oncorhynchus nerka were intercepted while migrating in the ocean and upstream in freshwater over a combined distance of more than 1,300 km to determine physiological and endocrine changes associated with ionoregulation. Sockeye migrating through seawater and freshwater showed consistent declines in gill Na+/K+ -ATPase (NKA) activity, plasma osmolality and plasma chloride concentration. In contrast, plasma sodium concentration became elevated in seawater as fish approached the river mouth and was then restored after sockeye entered the river. Accompanying the movement from seawater to freshwater was a significant increase in mRNA for the NKA α1a subunit in the gill, with little change in the α1b subunit. Potential endocrine signals stimulating the physiological changes during migration were assessed by measuring plasma cortisol and prolactin (Prl) concentrations and quantifying mRNA extracted from the gill for glucocorticoid receptors 1 and 2 (GR1 and GR2), mineralocorticoid receptor (MR), growth hormone 1 receptor (GH1R), and prolactin receptor (PrlR). Plasma cortisol and prolactin concentrations were high in seawater suggesting a preparatory endocrine signal before freshwater entry. Generally, the mRNA expression for GR1, GR2 and MR declined during migration, most notably after fish entered freshwater. In contrast, PrlR mRNA increased throughout migration, particularly as sockeye approached the spawning grounds. A highly significant association existed between gill PrlR mRNA and gill NKA α1a mRNA. GH1R mRNA also increased significantly, but only after sockeye had migrated beyond tidal influence in the river and then again just before the fish reached the spawning grounds. These findings suggest that cortisol and prolactin stimulate ionoregulation in the gill as sockeye salmon adapt to freshwater.

River habitat assessment for ecological restoration of Wei River Basin, China.

PubMed

Yang, Tao; Wang, Shuo; Li, Xiaoping; Wu, Ting; Li, Li; Chen, Jia

2018-04-11

As an important composition component of river ecosystems, river habitats must undergo quality assessment to potentially provide scientific basis for river ecological restoration. Substrate composition, habitat complexity, bank erosion degree, river meandering degree, human activity intensity, vegetation buffer width, water quality, and water condition were determined as indicators for river habitat assessment. The comprehensive habitat quality index (CHQI) was established for the Wei River Basin. In addition, the indicator values were determined on the basis of a field investigation at 12 national hydrological stations distributed across the Wei, Jing, and Beiluo Rivers. The analytic hierarchy process was used to determine the indicator weights and thus distinguish the relative importance of the assessment indicator system. Results indicated that the average CHQIs for the Wei, Jing, and Beiluo Rivers were 0.417, 0.508, and 0.304, respectively. The river habitat quality for the three rivers was well. As for the whole river basin, the river habitat quality for 25% of the cross section was very well, the other 25% was well, and the 50% remaining was in critical state. The river habitat quality of the Jing River was better than that of the Wei and Beiluo Rivers.

Electronic tags and genetics explore variation in migrating steelhead kelts (oncorhynchus mykiss), Ninilchik river, Alaska

USGS Publications Warehouse

Nielsen, J.L.; Turner, S.M.; Zimmerman, C.E.

2011-01-01

Acoustic and archival tags examined freshwater and marine migrations of postspawn steelhead kelts (Oncorhynchus mykiss) in the Ninilchik River, Alaska, USA. Postspawn steelhead were captured at a weir in 2002-2005. Scale analysis indicated multiple migratory life histories and spawning behaviors. Acoustic tags were implanted in 99 kelts (2002-2003), and an array of acoustic receivers calculated the average speed of outmigration, timing of saltwater entry, and duration of residency in the vicinity of the river mouth. Ocean migration data were recovered from two archival tags implanted in kelts in 2004 (one male and one female). Archival tags documented seasonal differences in maximum depth and behavior with both fish spending 97% of time at sea <6 m depth (day and night). All study fish were double tagged with passive integrated transponder (PIT) tags implanted in the body cavity. Less than 4% of PIT tags were retained in postspawn steelhead. Molecular genetics demonstrated no significant differences in genetic population structure across years or among spawning life history types, suggesting a genetically panmictic population with highly diverse life history characteristics in the Ninilchik River.

Superconducting properties of NbN film, bridge and meanders

NASA Astrophysics Data System (ADS)

Joshi, Lalit M.; Verma, Apoorva; Gupta, Anurag; Rout, P. K.; Husale, Sudhir; Budhani, R. C.

2018-05-01

The transport properties of superconducting NbN nanostructures in the form of thin film, bridge of width (w) = 50 μm and three meanders of w = 500, 250 and 100 nm have been investigated by resistance (R) measurements in temperature (T) range = 2 -300 K and magnetic field (B) range = 0 - 7 Tesla. The nanostructuring was carried out using Focused Ion Beam (FIB) milling. Reduction of sample width results in significant changes in the normal and superconducting state properties. For instance, the observed metallic behavior in the thin film sample is lost and the normal state resistance increases drastically from 2.4 Ω to 418 kΩ for the 100 nm meander. In the superconducting state, the value of critical temperature Tc (upper critical field Bc2 at T = 0 K) reduces gradually with width reduction, it changes from 13.15 K (42.8 Tesla) in the case of thin film sample to 5.7 K (12.7 Tesla) for the 100 nm meander sample. The superconducting transitions are found to get broader for the bridge sample and the meanders additionally show low-temperature resistive tails. In case of all the samples with reduced width, the transition onsets are found to be rounded at surprisingly high values of T ˜ 25 K >> Tc. These results are discussed in terms of the possible effects of FIB processing and weak localization in our samples.

Meandered-line antenna with integrated high-impedance surface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forman, Michael A.

2010-09-01

A reduced-volume antenna composed of a meandered-line dipole antenna over a finite-width, high-impedance surface is presented. The structure is novel in that the high-impedance surface is implemented with four Sievenpiper via-mushroom unit cells, whose area is optimized to match the meandered-line dipole antenna. The result is an antenna similar in performance to patch antenna but one fourth the area that can be deployed directly on the surface of a conductor. Simulations demonstrate a 3.5 cm ({lambda}/4) square antenna with a bandwidth of 4% and a gain of 4.8 dBi at 2.5 GHz.

Lake Murray, Fly and Strickland River Basins, Papua, New Guinea

NASA Image and Video Library

1991-12-01

Lake Murray, a manmade reservoir, lies between the Fly and Strickland River Basins, Papua, New Guinea (7.0S, 141.5E). The region, photographed in sunglint, shows the water level in the reservoir and the full extent of the drainage basins of both river systems as the rivers meander through wide alluvial floodplains. Some forest clearing can be seen in places throughout the region, but most of the area remains in closed canopy forest.

A multifaceted approach to prioritize and design bank stabilization measures along the Big Sioux River, South Dakota, USA

USDA-ARS?s Scientific Manuscript database

A multifaceted approach was used to manage fine-grained sediment loadings from river bank erosion along the Big Sioux River between Dell Rapids and Sioux Falls, South Dakota, USA. Simulations with the RVR Meander and CONCEPTS river-morphodynamics computer models were conducted to identify stream-ban...

Gypsum scarps and asymmetric fluvial valleys in evaporitic terrains. The role of river migration, landslides, karstification and lithology (Ebro River, NE Spain)

NASA Astrophysics Data System (ADS)

Guerrero, J.; Gutiérrez, F.

2017-11-01

Most of the Spanish fluvial systems excavated in Tertiary evaporitic gypsum formations show asymmetric valleys characterized by a stepped sequence of fluvial terraces on one valley flank and kilometric-long and > 100-m high prominent river scarp on the opposite side of the valley. Scarp undermining by the continuous preferential lateral migration of the river channel toward the valley margin leads to vertical to overhanging unstable slopes affected by a large number of slope failures that become the main geological hazard for villages located at the toe of the scarps. Detailed mapping of the gypsum scarps along the Ebro and Huerva Rivers gypsum scarps demonstrates that landslides and lateral spreading processes are predominant when claystones crop out at the base of the scarp, while rockfalls and topples become the dominant movement in those reaches where the rock mass is mainly constituted by evaporites. The dissolution of gypsum nodules, seasonal swelling and shrinking, and dispersion processes contribute to a decrease in the mechanical strength of claystones. The existence of dissolution-enlarged joints, sinkholes, and severely damaged buildings at the toe of the scarp from karstic subsidence demonstrates that the interstratal karstification of evaporites becomes a triggering factor in the instability of the rock mass. The genesis of asymmetric valleys and river gypsum scarps in the study area seem to be caused by the random migration of the river channel in the absence of lateral tilting related to tectonics or dissolution-induced subsidence. Once the scarp is developed, its preservation depends on the physicochemical properties of the substratum, the ratio between bedrock erosion and river incision rates, and climatic conditions that favour runoff erosion versus dissolution.

Sediment records of Yellow River channel migration and Holocene environmental evolution of the Hetao Plain, northern China

NASA Astrophysics Data System (ADS)

Wang, Jingzhong; Wu, Jinglu; Pan, Baotian; Jia, Hongjuan; Li, Xiao; Wei, Hao

2018-05-01

The origin and evolution of lakes in the Hetao Plain, northern China, were influenced by climate variation, channel migration, and human activity. We analyzed a suite of sediment cores from the region to investigate Yellow River channel migration and environmental change in this region over the Holocene. Short sediment cores show that environmental indicators changed markedly around CE 1850, a time that corresponds to flood events, when large amounts of river water accumulated in the western part of the Hetao Plain, giving rise to abundant small lakes. Multiple sediment variables (environmental proxies) from two long cores collected in the Tushenze Paleolake area show that sediments deposited between 12.0 and 9.0 cal ka BP were yellow clay, indicative of fluvial deposition and channel migration. From 9.0 to 7.5 cal ka BP, sand was deposited, reflecting a desert environment. From 7.5 to 2.2 cal ka BP, however, the sediments were blue-gray clay that represents lacustrine facies of Lake Tushenze, which owes its origin to an increase in strength of the East Asian monsoon. At about 2.2 cal ka BP, the north branch of the Yellow River was flooded, and the Tushenze Paleolake developed further. Around 2.0 cal ka BP, the paleolake shrank and eolian sedimentation was recorded. The analyzed sediment records are consistent with the written history from the region, which documents channel migration and environmental changes in the Hetao Plain over the Holocene.

From Shoestring Rills to Dendritic River Networks: Documenting the Evolution of River Basins Towards Geometric Similarity Through Divide Migration, Stream Capture and Lateral Branching

NASA Astrophysics Data System (ADS)

Beeson, H. W.; McCoy, S. W.; Willett, S.

2016-12-01

Erosional river networks dissect much of Earth's surface into drainage basins. Global scaling laws such as Hack's Law suggest that river basins trend toward a particular scale-invariant shape. While erosional instabilities arising from competition between advective and diffusive processes can explain why headwaters branch, the erosional mechanics linking larger scale network branching with evolution towards a characteristic river basin shape remain poorly constrained. We map river steepness and a proxy for the steady-state elevation of river networks, χ, in simulated and real landscapes with a large range in spatial scale (102 -106 m) but with similar inclined, planar surfaces at the time of incipient network formation. We document that the evolution from narrow rill-like networks to dendritic, leaf-shaped river basins follows from drainage area differences between catchments. These serve as instabilities that grow, leading to divide migration, stream capture, lateral branching and network reorganization. As Horton hypothesized, incipient networks formed down gradient on an inclined, planar surface have an unequal distribution of drainage area and nonuniformity in response times such that larger basins erode more rapidly and branch laterally via capture of adjacent streams with lower erosion rates. Positive feedback owing to increase in drainage area furthers the process of branching at the expense of neighboring rivers. We show that drainage area exchange and the degree of network reorganization has a significant effect on river steepness in the Dragon's Back Pressure Ridge, CA, the Sierra Nevada, CA, and the Rocky Mountain High Plains, USA. Similarly, metrics of basin shape reveal that basins are evolving from narrow basins towards more common leaf shapes. Our results suggest that divide migration and stream capture driven by erosional disequilibrium could be fundamental processes by which river basins reach their characteristic geometry and dendritic form.

Simulating bank erosion over an extended natural sinuous river reach using a universal slope stability algorithm coupled with a morphodynamic model

NASA Astrophysics Data System (ADS)

Rousseau, Yannick Y.; Van de Wiel, Marco J.; Biron, Pascale M.

2017-10-01

Meandering river channels are often associated with cohesive banks. Yet only a few river modelling packages include geotechnical and plant effects. Existing packages are solely compatible with single-threaded channels, require a specific mesh structure, derive lateral migration rates from hydraulic properties, determine stability based on friction angle, rely on nonphysical assumptions to describe cutoffs, or exclude floodplain processes and vegetation. In this paper, we evaluate the accuracy of a new geotechnical module that was developed and coupled with Telemac-Mascaret to address these limitations. Innovatively, the newly developed module relies on a fully configurable, universal genetic algorithm with tournament selection that permits it (1) to assess geotechnical stability along potentially unstable slope profiles intersecting liquid-solid boundaries, and (2) to predict the shape and extent of slump blocks while considering mechanical plant effects, bank hydrology, and the hydrostatic pressure caused by flow. The profiles of unstable banks are altered while ensuring mass conservation. Importantly, the new stability module is independent of mesh structure and can operate efficiently along multithreaded channels, cutoffs, and islands. Data collected along a 1.5-km-long reach of the semialluvial Medway Creek, Canada, over a period of 3.5 years are used to evaluate the capacity of the coupled model to accurately predict bank retreat in meandering river channels and to evaluate the extent to which the new model can be applied to a natural river reach located in a complex environment. Our results indicate that key geotechnical parameters can indeed be adjusted to fit observations, even with a minimal calibration effort, and that the model correctly identifies the location of the most severely eroded bank regions. The combined use of genetic and spatial analysis algorithms, in particular for the evaluation of geotechnical stability independently of the hydrodynamic

Distribution and Joint Fish-Tag Survival of Juvenile Chinook Salmon Migrating through the Sacramento-San Joaquin River Delta, California, 2008

USGS Publications Warehouse

Holbrook, Christopher M.; Perry, Russell W.; Adams, Noah S.

2009-01-01

Acoustic telemetry was used to obtain the movement histories of 915 juvenile fall-run Chinook salmon (Oncorhynchus tshawytscha) through the lower San Joaquin River and Sacramento-San Joaquin Delta, California, in 2008. Data were analyzed within a release-recapture framework to estimate survival, route distribution, and detection probabilities among three migration pathways through the Delta. The pathways included the primary route through the San Joaquin River and two less direct routes (Old River and Turner Cut). Strong inferences about survival were limited by premature tag failure, but estimates of fish distribution among migration routes should be unaffected by tag failure. Based on tag failure tests (N = 66 tags), we estimated that only 55-78 percent of the tags used in this study were still functioning when the last fish was detected exiting the study area 15 days after release. Due to premature tag failure, our 'survival' estimates represent the joint probability that both the tag and fish survived, not just survival of fish. Low estimates of fish-tag survival could have been caused by fish mortality or fish travel times that exceeded the life of the tag, but we were unable to differentiate between the two. Fish-tag survival through the Delta (from Durham Ferry to Chipps Island by all routes) ranged from 0.05 +or- 0.01 (SE) to 0.06 +or- 0.01 between the two weekly release groups. Among the three migration routes, fish that remained in the San Joaquin River exhibited the highest joint fish-tag survival (0.09 +or- 0.02) in both weeks, but only 22-33 percent of tagged fish used this route, depending on the week of release. Only 4-10 percent (depending on week) of tagged fish traveled through Turner Cut, but no tagged fish that used this route were detected exiting the Delta. Most fish (63-68 percent, depending on week of release) migrated through Old River, but fish-tag survival through this route (0.05 +or- 0.01) was only about one-half that of fish that

Sedimentation rate and lateral migration of tidal channels in the Lagoon of Venice (Northern Italy)

NASA Astrophysics Data System (ADS)

Donnici, Sandra; Madricardo, Fantina; Serandrei-Barbero, Rossana

2017-11-01

Tidal channels are crucial for the functioning of highly valuable coastal environments, such as estuaries and lagoons. Their properties, however, are currently less understood than those of river systems. To elucidate their past behaviour, an extensive geophysical investigation was performed to reconstruct the evolution of channels and tidal surfaces in the central part of the Lagoon of Venice (Italy) over the past 5000 years. Comparing high-spatial-resolution acoustic data and sedimentary facies analyses of 41 cores, 29 of which were radiocarbon dated, revealed the sedimentation rates in different lagoonal environments and allowed the migration of two large meanders to be reconstructed. The average sedimentation rate of the study succession in the different sedimentary environments was 1.27 mm yr-1. The lateral migration rates were 13-23 m/century. This estimate is consistent with the lateral migration rates determined by comparing aerial photographs of recent channels. Comparing the buried channels with historical and current maps showed that, in general, the number of active channels is now reduced. Their morphology was sometimes simplified by artificial interventions. An understanding of the impact of the artificial interventions over time is useful for the management and conservation of tidal environments, particularly for the Lagoon of Venice, where management authorities are currently debating the possible deepening and rectification of large navigation channels.

Migration and spawning of radio-tagged zulega Prochilodus argenteus in a dammed Brazilian river

USGS Publications Warehouse

Godinho, Alexandre L.; Kynard, B.

2006-01-01

It is difficult for agencies to evaluate the impacts of the many planned dams on Sa??o Francisco River, Brazil, migratory fishes because fish migrations are poorly known. We conducted a study on zulega Prochilodus argenteus, an important commercial and recreational fish in the Sa??o Francisco River, to identify migrations and spawning areas and to determine linear home range. During two spawning seasons (2001-2003), we radio-tagged fish in three main-stem reaches downstream of Tre??s Marias Dam (TMD), located at river kilometer (rkm) 2,109. We tagged 10 fish at Tre??s Marias (TM), which is 5 km downstream of TMD; 12 fish at Pontal, which is 28 km downstream of TMD and which includes the mouth of the Abaete?? River, and 10 fish at Cilga, which is 45 km downstream of TMD. Late-stage (ripe) adults tagged in each area during the spawning season remained at or near the tagging site, except for four Cilga fish that went to Pontal and probably spawned. The Pontal area at the Abaete?? River mouth was the most important spawning site we found. Prespawning fish moved back and forth between main-stem staging areas upstream of the Abaete?? River mouth and Pontal for short visits. These multiple visits were probably needed as ripe fish waited for spawning cues from a flooding Abaete?? River. Some fish homed to prespaw ning staging areas, spawning areas, and nonspawning areas. The migratory style of zulega was dualistic, with resident and migratory fish. Total linear home range was also dualistic, with small (<26-km) and large (53-127-km) ranges. The locations of spawning areas and home ranges suggest that the Pontal group (which includes Cilga fish) is one population that occupies about 110 km. The Pontal population overlaps a short distance with a population located downstream of Cilga. Movements of late-stage TM adults suggest that the TM group is a separate population, possibly with connections to populations upstream of TMD. ?? Copyright by the American Fisheries Society

Hydro-geomorphology of the middle Elwha River, Washington, following dam removal

NASA Astrophysics Data System (ADS)

Morgan, J. A.; Nelson, P. A.; Brogan, D. J.

2017-12-01

Dam removal is an increasingly common river restoration practice, which can produce dramatic increases in sediment supply to downstream reaches. There remains, however, considerable uncertainty in how mesoscale morphological units (e.g., riffles and pools) respond to the flow and sediment supply changes associated with dam removal. The recent removal of Glines Canyon Dam on the Elwha River in Washington State provides a natural setting to explore how increased sediment supply due to dam removal may affect downstream reaches. Here, we present observations and surveys documenting how a 1 km reach, located approximately 5 km downstream of the former dam site, has evolved following dam removal. Annual topographic/bathymetric surveys were conducted in 2014-2016 using RTK-GNSS methods, and these surveys were coupled with airborne lidar to create continuous surface maps of the valley bottom. Differencing the elevation models reveals channel widening and migration due to lateral bank retreat and bar aggradation. Analysis of aerial imagery dating back to 1939 suggests that rates of both widening and meander migration have increased following dam removal. We also used results from depth-averaged hydrodynamic modeling with a fuzzy c-means clustering approach to delineate riffle and pool units; this analysis suggests that both riffles and pools stayed relatively consistent from 2014-2015, while both areas decreased from 2015 to 2016. Without any considerable changes to the hydrologic regime these higher rates of change are implied to be the result of the increased sediment supply. Our results, which indicate an increased dynamism due directly to the amplified sediment supply, have the potential to further inform river managers and restoration specialists who oversee projects related to changing sediment regimes.

Ecological carryover effects associated with partial migration in white perch (Morone americana) within the Hudson River Estuary

NASA Astrophysics Data System (ADS)

Gallagher, Brian K.; Piccoli, Philip M.; Secor, David H.

2018-01-01

Partial migration in complex life cycles allows environmental conditions experienced during one life-stage to interact with genetic thresholds and produce divergent spatial behaviors in the next stage. We evaluated partial migration over the entire life cycle of white perch, (Morone americana) within the Hudson River Estuary, combining otolith microchemistry, population demographics and environmental data analysis. Ecological carryover effects were used as a framework to test how environmental variation during the larval period influenced migration behaviors and growth characteristics in subsequent life-stages. Two annual cohorts of juveniles were classified based on whether they persisted in natal habitats (freshwater resident contingent) or dispersed into non-natal habitats (brackish water migratory contingent) as juveniles. The migratory contingent tended to hatch earlier and experience cooler temperatures as larvae, while the availability of zooplankton prey during the larval period appeared to influence growth dynamics before and after metamorphosis. Juvenile migration behaviors were reversible but usually persisted into adulthood. As juveniles, the consequences of partial migration on growth appeared to be modified by river flow, as demonstrated by the influence of a large storm event on feeding conditions in one of the study years. Migratory adults grew faster and attained larger maximum sizes, but may also experience higher rates of mortality. The interplay uncovered between life-stage transitions, conditional migration behaviors and habitat productivity throughout the life cycle shapes white perch population dynamics and will likely play an important role in responses to long-term environmental change.

Plasma insulin-like growth factor-I concentrations in yearling chinook salmon (Oncorhynchus tshawytscha) migrating from the Snake River Basin, USA

USGS Publications Warehouse

Congleton, J.L.; Biga, P.R.; Peterson, B.C.

2003-01-01

During the parr-to-smolt transformation (smoltification) of juvenile salmonids, preadaptive changes in osmoregulatory and ionoregulatory ability are regulated in part by the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis. If food intake is sufficient, plasma IGF-I increases during smoltification. On the other hand, plasma IGF-I typically decreases in fasting fish and other vertebrate animals. Because food availability is limited for juvenile salmonids undertaking an extended 6- to 12-week spring migration to and through the Snake-Columbia River hydropower system (northwestern USA), IGF-I concentrations might be expected to decrease, potentially compromising seawater tolerance. To address this possibility, yearling chinook salmon Oncorhynchus tshawytscha reared in three Snake River Basin hatcheries were sampled before release and at two downstream dams. Dry masses of migrating fish either did not increase during the migration (in 2000, an average-flow year), or decreased significantly (in 2001, a low-flow year). In both years, plasma IGF-I levels were significantly higher (1.6-fold in 2000, 3.7-fold in 2001) for fish sampled at the last dam on the lower Columbia River than for fish sampled prior to release. Plasma IGF-I concentrations in migrating fish may, nonetheless, have been nutritionally down-regulated to some degree, because plasma IGF-I concentrations in juvenile chinook salmon captured at a Snake River dam and transported to the laboratory increased in fed groups, but decreased in unfed groups. The ability of migrating smolts to maintain relatively elevated IGF-I levels despite restricted food intake and loss of body mass is likely related to smoltification-associated changes in hormonal balance. ?? 2004 Kluwer Academic Publishers.

Boundary shear stress along rigid trapezoidal bends

Treesearch

Christopher I. Thornton; Kyung-Seop Sin; Paul Sclafani; Steven R. Abt

2012-01-01

The migration of alluvial channels through the geologic landform is an outcome of the natural erosive processes. Mankind continually attempts to stabilize channel meandering processes, both vertically and horizontally, to reduce sediment discharge, provide boundary definition, and enable economic development along the river's edge. A critical component in the...

Wake meandering of a model wind turbine operating in two different regimes

NASA Astrophysics Data System (ADS)

Foti, Daniel; Yang, Xiaolei; Campagnolo, Filippo; Maniaci, David; Sotiropoulos, Fotis

2018-05-01

The flow behind a model wind turbine under two different turbine operating regimes (region 2 for turbine operating at optimal condition with the maximum power coefficient and 1.4-deg pitch angle and region 3 for turbine operating at suboptimal condition with a lower power coefficient and 7-deg pitch angle) is investigated using wind tunnel experiments and numerical experiments using large-eddy simulation (LES) with actuator surface models for turbine blades and nacelle. Measurements from the model wind turbine experiment reveal that the power coefficient and turbine wake are affected by the operating regime. Simulations with and without a nacelle model are carried out for each operating condition to study the influence of the operating regime and nacelle on the formation of the hub vortex and wake meandering. Statistics and energy spectra of the simulated wakes are in good agreement with the measurements. For simulations with a nacelle model, the mean flow field is composed of an outer wake, caused by energy extraction by turbine blades, and an inner wake directly behind the nacelle, while for the simulations without a nacelle model, the central region of the wake is occupied by a jet. The simulations with the nacelle model reveal an unstable helical hub vortex expanding outward toward the outer wake, while the simulations without a nacelle model show a stable and columnar hub vortex. Because of the different interactions of the inner region of the wake with the outer region of the wake, a region with higher turbulence intensity is observed in the tip shear layer for the simulation with a nacelle model. The hub vortex for the turbine operating in region 3 remains in a tight helical spiral and intercepts the outer wake a few diameters further downstream than for the turbine operating in region 2. Wake meandering, a low-frequency large-scale motion of the wake, commences in the region of high turbulence intensity for all simulations with and without a nacelle model

A numerical study of the complex flow structure in a compound meandering channel

NASA Astrophysics Data System (ADS)

Moncho-Esteve, Ignacio J.; García-Villalba, Manuel; Muto, Yasu; Shiono, Koji; Palau-Salvador, Guillermo

2018-06-01

In this study, we report large eddy simulations of turbulent flow in a periodic compound meandering channel for three different depth conditions: one in-bank and two overbank conditions. The flow configuration corresponds to the experiments of Shiono and Muto (1998). The predicted mean streamwise velocities, mean secondary motions, velocity fluctuations, turbulent kinetic energy as well as mean flood flow angle to meandering channel are in good agreement with the experimental measurements. We have analyzed the flow structure as a function of the inundation level, with particular emphasis on the development of the secondary motions due to the interaction between the main channel and the floodplain flow. Bed shear stresses have been also estimated in the simulations. Floodplain flow has a significant impact on the flow structure leading to significantly different bed shear stress patterns within the main meandering channel. The implications of these results for natural compound meandering channels are also discussed.

Estimating freshwater productivity, overwinter survival, and migration patterns of Klamath River Coho Salmon

USGS Publications Warehouse

Manhard, Christopher V.; Som, Nicholas A.; Perry, Russell W.; Faukner, Jimmy; Soto, Toz

2018-01-01

An area of great importance to resource management and conservation biology in the Klamath Basin is balancing water usage against the life history requirements of threatened Coho Salmon. One tool for addressing this topic is a freshwater dynamics model to forecast Coho Salmon productivity based on environmental inputs. Constructing such a forecasting tool requires local data to quantify the unique life history processes of Coho Salmon inhabiting this region. Here, we describe analytical methods for estimating a series of sub-models, each capturing a different life history process, which will eventually be synchronized as part of a freshwater dynamics model for Klamath River Coho Salmon. Specifically, we draw upon extensive population monitoring data collected in the basin to estimate models of freshwater productivity, overwinter survival, and migration patterns. Our models of freshwater productivity indicated that high summer temperatures and high winter flows can both adversely affect smolt production and that such relationships are more likely in tributaries with naturally regulated flows due to substantial intraannual environmental variation. Our models of overwinter survival demonstrated extensive variability in survival among years, but not among rearing locations, and demonstrated that a substantial proportion (~ 20%) of age-0+ fish emigrate from some rearing sites in the winter. Our models of migration patterns indicated that many age-0+ fish redistribute in the basin during the summer and winter. Further, we observed that these redistributions can entail long migrations in the mainstem where environmental stressors likely play a role in cueing refuge entry. Finally, our models of migration patterns indicated that changes in discharge are important in cueing the seaward migration of smolts, but that the nature of this behavioral response can differ dramatically between tributaries with naturally and artificially regulated flows. Collectively, these analyses

River banks and channel axis curvature: Effects on the longitudinal dispersion in alluvial rivers

NASA Astrophysics Data System (ADS)

Lanzoni, Stefano; Ferdousi, Amena; Tambroni, Nicoletta

2018-03-01

The fate and transport of soluble contaminants released in natural streams are strongly dependent on the spatial variations of the flow field and of the bed topography. These variations are essentially related to the presence of the channel banks and to the planform configuration of the channel. Large velocity gradients arise near to the channel banks, where the flow depth decreases to zero. Moreover, single thread alluvial rivers are seldom straight, and usually exhibit meandering planforms and a bed topography that deviates from the plane configuration. Channel axis curvature and movable bed deformations drive secondary helical currents which enhance both cross sectional velocity gradients and transverse mixing, thus crucially influencing longitudinal dispersion. The present contribution sets up a rational framework which, assuming mild sloping banks and taking advantage of the weakly meandering character often exhibited by natural streams, leads to an analytical estimate of the contribution to longitudinal dispersion associated with spatial non-uniformities of the flow field. The resulting relationship stems from a physics-based modeling of the flow in natural rivers, and expresses the bend averaged longitudinal dispersion coefficient as a function of the relevant hydraulic and morphologic parameters. The treatment of the problem is river specific, since it relies on an explicit spatial description, although linearized, of the flow field that establishes in the investigated river. Comparison with field data available from tracer tests supports the robustness of the proposed framework, given also the complexity of the processes that affect dispersion dynamics in real streams.

Plume meander and dispersion in a stable boundary layer

NASA Astrophysics Data System (ADS)

Hiscox, April L.; Miller, David R.; Nappo, Carmen J.

2010-11-01

Continuous lidar measurements of elevated plume dispersion and corresponding micrometeorology data are analyzed to establish the relationship between plume behavior and nocturnal boundary layer dynamics. Contrasting nights of data from the JORNADA field campaign in the New Mexico desert are analyzed. The aerosol lidar measurements were used to separate the plume diffusion (plume spread) from plume meander (displacement). Mutiresolution decomposition was used to separate the turbulence scale (<90 s) from the submesoscale (>90 s). Durations of turbulent kinetic energy stationarity and the wind steadiness were used to characterize the local scale and submesoscale turbulence. Plume meander, driven by submesoscale wind motions, was responsible for most of the total horizontal plume dispersion in weak and variable winds and strong stability. This proportion was reduced in high winds (i.e., >4 m s-1), weakly stable conditions but remained the dominant dispersion mechanism. The remainder of the plume dispersion in all cases was accounted for by internal spread of the plume, which is a small eddy diffusion process driven by turbulence. Turbulence stationarity and the wind steadiness are demonstrated to be closely related to plume diffusion and plume meander, respectively.

Migration of the Pee Dee River system inferred from ancestral paleochannels underlying the South Carolina Grand Strand and Long Bay inner shelf

USGS Publications Warehouse

Baldwin, W.E.; Morton, R.A.; Putney, T.R.; Katuna, M.P.; Harris, M.S.; Gayes, P.T.; Driscoll, N.W.; Denny, J.F.; Schwab, W.C.

2006-01-01

Several generations of the ancestral Pee Dee River system have been mapped beneath the South Carolina Grand Strand coastline and adjacent Long Bay inner shelf. Deep boreholes onshore and high-resolution seismic-reflection data offshore allow for reconstruction of these paleochannels, which formed during glacial lowstands, when the Pee Dee River system incised subaerially exposed coastal-plain and continental-shelf strata. Paleochannel groups, representing different generations of the system, decrease in age to the southwest, where the modern Pee Dee River merges with several coastal-plain tributaries at Winyah Bay, the southern terminus of Long Bay. Positions of the successive generational groups record a regional, southwestward migration of the river system that may have initiated during the late Pliocene. The migration was primarily driven by barrier-island deposition, resulting from the interaction of fluvial and shoreline processes during eustatic highstands. Structurally driven, subsurface paleotopography associated with the Mid-Carolina Platform High has also indirectly assisted in forcing this migration. These results provide a better understanding of the evolution of the region and help explain the lack of mobile sediment on the Long Bay inner shelf. Migration of the river system caused a profound change in sediment supply during the late Pleistocene. The abundant fluvial source that once fed sand-rich barrier islands was cut off and replaced with a limited source, supplied by erosion and reworking of former coastal deposits exposed at the shore and on the inner shelf.

Richness and diversity of helminth communities in the Japanese grenadier anchovy, Coilia nasus, during its anadromous migration in the Yangtze River, China.

PubMed

Li, Wen X; Zou, Hong; Wu, Shan G; Song, Rui; Wang, Gui T

2012-06-01

To determine the relationship between the species richness, diversity of helminth communities, and migration distance during upward migration from coast to freshwater, helminth communities in the anadromous fish Coilia nasus were investigated along the coast of the East China Sea, the Yangtze Estuary, and 3 localities on the Yangtze River. Six helminth species were found in 224 C. nasus . Changes in salinity usually reduced the survival time of parasites, and thus the number of helminth species and their abundance. Except for the 2 dominant helminths, the acanthocephalan Acanthosentis cheni and the nematode Contracaecum sp., mean abundance of other 4 species of helminths was rather low (<1.0) during the upward migration in the Yangtze River. Mean abundance of the 2 dominant helminths peaked in the Yangtze Estuary and showed no obvious decrease among the 3 localities on the Yangtze River. Mean species richness, Brillouin's index, and Shannon index were also highest in the estuary (1.93 ± 0.88, 0.28 ± 0.25, and 0.37 ± 0.34, respectively) and did not exhibit marked decline at the 3 localities on the Yangtze River. A significant negative correlation was not seen between the similarity and the geographical distance (R  =  -0.5104, P  =  0.1317). The strong salinity tolerance of intestinal helminths, relatively brief stay in the Yangtze River, and large amount of feeding on small fish and shrimp when commencing spawning migration perhaps were responsible for the results.

Temporal variation of meandering intensity and domain-wide lateral oscillations of the Gulf Stream

NASA Technical Reports Server (NTRS)

Lee, Tong; Cornillon, Peter

1995-01-01

The path of the Gulf Stream exhibits two modes of variability: wavelike spatial meanders associated with instability processes and large-sale lateral shifts of the path presumably due to atmospheric forcing. The objectives of this study are to examine the temporal variation of the intensity of spatial meandering in the stream, to characterize large-scale lateral oscillations in the stream's path, and to study the correlation betwen these two dynamically distinct modes of variability. The data used for this analysis are path displacemets ofthe Gulf Stream between 75 deg and 60 deg W obtained from AVHRR-derived (Advanced Very High Resolution Radiometer) infrared images for the period April 1982 through December 1989. Meandering intensity, measured by the spatial root-mean-sqaure displacement of the stream path, displays a 9-month dominant periodicity which is persistent through the study period. The 9-month fluctuation in meandering intensity may be related to the interaction of Rosseby waves with the stream. Interannual variation of meandering intensity is also found to be significant, with meandering being mich more intense during 1985 than it was in 1987. Annual variation, however,is weak and not well-defined.The spatially averaged position of the stream, which reflects nonmeandering large-scale lateral oscillations of the stream path, is dominated by an annual cycle. On average, the mean position is farthest north in November and farthest south in April. The first empirical orthogonal function mode of the space-time path displacements represents lateral oscillatins that are in-phase over the space-time domain. Interannual oscillations are also observed and are found to be weaker than the annual oscillation. The eigenvalue of the first mode indicates that about 21.5% of the total space-time variability of the stream path can be attibuted to domain-wide lateral oscillation. The correlation between meandering intensity and domain-wide lateral oscillations is very

Ionoregulatory changes in different populations of maturing sockeye salmon Oncorhynchus nerka during ocean and river migration.

PubMed

Shrimpton, J M; Patterson, D A; Richards, J G; Cooke, S J; Schulte, P M; Hinch, S G; Farrell, A P

2005-11-01

We present the first data on changes in ionoregulatory physiology of maturing, migratory adult sockeye salmon Oncorhynchus nerka. Fraser River sockeye were intercepted in the ocean as far away as the Queen Charlotte Islands (approximately 850 km from the Fraser River) and during freshwater migration to the spawning grounds; for some populations this was a distance of over 700 km. Sockeye migrating in seawater toward the mouth of the Fraser River and upriver to spawning grounds showed a decline in gill Na+,K+-ATPase activity. As a result, gill Na+,K+-ATPase activity of fish arriving at the spawning grounds was significantly lower than values obtained from fish captured before entry into freshwater. Plasma osmolality and chloride levels also showed significant decreases from seawater values during the freshwater migration to spawning areas. Movement from seawater to freshwater increased mRNA expression of a freshwater-specific Na+,K+-ATPase isoform (alpha1a) while having no effect on the seawater-specific isoform (alpha1b). In addition, gill Na+,K+-ATPase activity generally increased in active spawners compared with unspawned fish on the spawning grounds and this was associated with a marked increase in Na+,K+-ATPase alpha1b mRNA. Increases in gill Na+,K+-ATPase activities observed in spawners suggests that the fish may be attempting to compensate for the osmotic perturbation associated with the decline in plasma chloride concentration and osmolality.

Including independent estimates and uncertainty to quantify total abundance of fish migrating in a large river system: walleye (Sander vitreus) in the Maumee River, Ohio

USGS Publications Warehouse

Pritt, Jeremy J.; DuFour, Mark R.; Mayer, Christine M.; Kocovsky, Patrick M.; Tyson, Jeffrey T.; Weimer, Eric J.; Vandergoot, Christopher S.

2013-01-01

Walleye (Sander vitreus) in Lake Erie is a valuable and migratory species that spawns in tributaries. We used hydroacoustic sampling, gill net sampling, and Bayesian state-space modeling to estimate the spawning stock abundance, characterize size and sex structure, and explore environmental factors cuing migration of walleye in the Maumee River for 2011 and 2012. We estimated the spawning stock abundance to be between 431,000 and 1,446,000 individuals in 2011 and between 386,400 and 857,200 individuals in 2012 (95% Bayesian credible intervals). A back-calculation from a concurrent larval fish study produced an estimate of 78,000 to 237,000 spawners for 2011. The sex ratio was skewed towards males early in the spawning season but approached 1:1 later, and larger individuals entered the river earlier in the season than smaller individuals. Walleye migration was greater during low river discharge and intermediate temperatures. Our approach to estimating absolute abundance and uncertainty as well as characterization of the spawning stock could improve assessment and management of this species, and our methodology is applicable to other diadromous populations.

Determination of real-time predictors of the wind turbine wake meandering

NASA Astrophysics Data System (ADS)

Muller, Yann-Aël; Aubrun, Sandrine; Masson, Christian

2015-03-01

The present work proposes an experimental methodology to characterize the unsteady properties of a wind turbine wake, called meandering, and particularly its ability to follow the large-scale motions induced by large turbulent eddies contained in the approach flow. The measurements were made in an atmospheric boundary layer wind tunnel. The wind turbine model is based on the actuator disc concept. One part of the work has been dedicated to the development of a methodology for horizontal wake tracking by mean of a transverse hot wire rake, whose dynamic response is adequate for spectral analysis. Spectral coherence analysis shows that the horizontal position of the wake correlates well with the upstream transverse velocity, especially for wavelength larger than three times the diameter of the disc but less so for smaller scales. Therefore, it is concluded that the wake is actually a rather passive tracer of the large surrounding turbulent structures. The influence of the rotor size and downstream distance on the wake meandering is studied. The fluctuations of the lateral force and the yawing torque affecting the wind turbine model are also measured and correlated with the wake meandering. Two approach flow configurations are then tested: an undisturbed incoming flow (modelled atmospheric boundary layer) and a disturbed incoming flow, with a wind turbine model located upstream. Results showed that the meandering process is amplified by the presence of the upstream wake. It is shown that the coherence between the lateral force fluctuations and the horizontal wake position is significant up to length scales larger than twice the wind turbine model diameter. This leads to the conclusion that the lateral force is a better candidate than the upstream transverse velocity to predict in real time the meandering process, for either undisturbed (wake free) or disturbed incoming atmospheric flows.

High-temperature superconducting nano-meanders made by ion irradiation

NASA Astrophysics Data System (ADS)

Amari, P.; Feuillet-Palma, C.; Jouan, A.; Couëdo, F.; Bourlet, N.; Géron, E.; Malnou, M.; Méchin, L.; Sharafiev, A.; Lesueur, J.; Bergeal, N.

2018-01-01

In this article, we report on the fabrication of very long {{YBa}}2{{Cu}}3{{{O}}}7 nanowires in a meander shape patterned in a {{CeO}}2-capped thin film by high-energy oxygen ion irradiation. DC and RF characterizations outline the good superconducting properties of the nanowires whose geometry approaches the one used in single photon detectors. Their inductance, which mainly sets the maximum speed of these devices, has been measured on a wide range of temperature by mean of a resonant method. The extracted values are in agreement with the ones calculated from the geometry of the meanders and from the known London penetration depth in {{YBa}}2{{Cu}}3{{{O}}}7 thin films.

Elements patterns of soil and river sediments as a tracer of sediment migration

NASA Astrophysics Data System (ADS)

Dordevic, Dragana; Pétursdóttir, Þórunn; Halldórsson, Guðmundur; Sakan, Sanja; Škrivalj, Sandra; Finger, David Christian

2017-04-01

Iceland is the small island on the mid Atlantic ridge, with strong natural catastrophes, such as floods, droughts, landslides, storms and volcanic eruptions that can have devastating impacts on natural and build environment. Rangárvellir area next to Mt Hekla and the glacier Tindfjallajökul has impacted by severe erosion processes but also rich of surface water that play a crucial role in sediment transport processes in the watersheds of the two rivers Eystri-Rangá and Ytri-Rangá. Their sediments consist of various materials originating from volcanoes ash and lava. Difference of contents of various chemical components in sediments and surrounding soil could be bases for identification of erosion processes and watersheds connectivity. River sediment is accumulator of chemical constituents from water in water-sediment interaction, making it as an important material for investigation their migration routes. In order to develop of methods for investigating of sediment migration using their chemical patterns the STSM of Connecteur COST Action ES1306-34336 have been approved. Samples of river sediments and surrounding soils of the Eystri-Rangá and Ytri-Rangá rivers in watersheds of Rangárvellir area as well as primarily volcanic ash from Eyafjallajökull were taken. Sequential extraction of heavy metals and trace elements from collected samples has been applied using the optimized procedure proposed by European Community Bureau of reference (BCR) in the next fractions: 1) soluble in acid - metals that are exchangeable or associated with carbonates; 2) reducible fraction - metals associated with oxides of Fe and Mn; 3) oxidizable fraction - metals associated with organic matter and sulfides and 4) residual fraction - metals strongly associated with the crystalline structure of minerals. Extracted solutions have analyzed by ICP/OES on next elements: Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Sb, Si, Sr, V, Zn. Distributions

Ocean-Atmosphere Interaction Over Agulhas Extension Meanders

NASA Technical Reports Server (NTRS)

Liu, W. Timothy; Xie, Xiaosu; Niiler, Pearn P.

2007-01-01

Many years of high-resolution measurements by a number of space-based sensors and from Lagrangian drifters became available recently and are used to examine the persistent atmospheric imprints of the semi-permanent meanders of the Agulhas Extension Current (AEC), where strong surface current and temperature gradients are found. The sea surface temperature (SST) measured by the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and the chlorophyll concentration measured by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) support the identification of the meanders and related ocean circulation by the drifters. The collocation of high and low magnitudes of equivalent neutral wind (ENW) measured by Quick Scatterometer (QuikSCAT), which is uniquely related to surface stress by definition, illustrates not only the stability dependence of turbulent mixing but also the unique stress measuring capability of the scatterometer. The observed rotation of ENW in opposition to the rotation of the surface current clearly demonstrates that the scatterometer measures stress rather than winds. The clear differences between the distributions of wind and stress and the possible inadequacy of turbulent parameterization affirm the need of surface stress vector measurements, which were not available before the scatterometers. The opposite sign of the stress vorticity to current vorticity implies that the atmosphere spins down the current rotation through momentum transport. Coincident high SST and ENW over the southern extension of the meander enhance evaporation and latent heat flux, which cools the ocean. The atmosphere is found to provide negative feedback to ocean current and temperature gradients. Distribution of ENW convergence implies ascending motion on the downwind side of local SST maxima and descending air on the upwind side and acceleration of surface wind stress over warm water (deceleration over cool water); the convection may escalate the contrast of

Patterns of migration and residency in coastal cutthroat trout Oncorhynchus clarkii clarkii from two tributaries of the lower Columbia River

USGS Publications Warehouse

Zydlewski, G.B.; Zydlewski, Joseph D.; Johnson, J.

2009-01-01

Coastal cutthroat trout Onchorhynchus clarkii clarkii life-history variants, migration and freshwater residency were monitored using stationary passive integrated transponder (PIT) tag arrays in two tributaries of the Columbia River from 2001 to 2005 (Abernathy Creek, river kilometre, rkm 76) and from 2002 to 2005 (Chinook River, rkm 6). In 2001-2003 and 2002-2003 (Abernathy and Chinook, respectively), 300-500 coastal O. c. clarkii were captured in each tributary by electrofishing and implanted with 23 mm PIT tags. PIT arrays monitored movements from the initiation of tagging through the spring of 2005. Rotary screw traps were also operated on both tributaries. In Abernathy Creek, 28% of tagged individuals were observed through either active capture or passive interrogation. Of these, 32% were identified as migrants and 68% were identified as residents. In the Chinook River, 48% of tagged fish were observed subsequent to tagging; 92% of these fish were migrants and only 8% were resident. In both tributaries, a greater proportion of resident fish were in the upper reaches. The majority of migrants (78-93%) moved the spring following tagging. Migrants leaving at age 2+ years tended to grow faster than those that migrated at age 3+ years or residents. Patterns of growth or growth opportunities may influence both patterns of life-history expression and the timing of migration. ?? 2009 The Fisheries Society of the British Isles.

THE GAPS BETWEEN AN INTEGRATED UNDERSTANDING OF CHANNELIZATION, HYDROLOGY AND WATER QUALITY VERSUS HOLISTIC FUTURE MANAGEMENT: A CASE STUDY OF THE WILLAMETTE RIVER, OREGON

EPA Science Inventory

Over the last 150 years the main channel of the Willamette River has been drastically altered by human activity. It has changed from a generally meandering and anastamosing river with extensive reaches of broad, active and connected flood plain features to a river with 13 major ...

Migration behavior and dispersal of adult spring Chinook salmon released into Lake Scanewa on the upper Cowlitz River during 2005

USGS Publications Warehouse

Perry, R.W.; Kock, Tobias J.; Kritter , M.A; Rondorf, Dennis W.

2007-01-01

During 2005, we conducted a radio-telemetry study to answer a number of basic questions about the migration behavior of adult Spring Chinook salmon (Oncorhynchus tshawytscha) released into the upper Cowlitz River watershed. We also conducted a pilot study of adult Coho salmon (Oncorhynchus kisutch) using radio-tags recovered from adult spring Chinook salmon. This data is included as an Appendix. Our study was designed to evaluate the dispersal of adult spring Chinook salmon to determine the proportion of the run 1) spawning in the Cispus River, 2) spawning in the Cowlitz River, 3) passing downstream through Cowlitz Falls Dam into Riffe Lake, and 4) remaining in Lake Scanewa. We also examined spatial patterns of movement in the study area and temporal patterns of fish movements. Last, we examined differences in migration behavior between hatchery and wild fish and male and female fish.

A hydrogeomorphic river network model predicts where and why hyporheic exchange is important in large basins

USGS Publications Warehouse

Gomez-Velez, Jesus D.; Harvey, Judson

2014-01-01

Hyporheic exchange has been hypothesized to have basin-scale consequences; however, predictions throughout river networks are limited by available geomorphic and hydrogeologic data and by models that can analyze and aggregate hyporheic exchange flows across large spatial scales. We developed a parsimonious but physically based model of hyporheic flow for application in large river basins: Networks with EXchange and Subsurface Storage (NEXSS). We applied NEXSS across a broad range of geomorphic diversity in river reaches and synthetic river networks. NEXSS demonstrates that vertical exchange beneath submerged bed forms rather than lateral exchange through meanders dominates hyporheic fluxes and turnover rates along river corridors. Per kilometer, low-order streams have a biogeochemical potential at least 2 orders of magnitude larger than higher-order streams. However, when biogeochemical potential is examined per average length of each stream order, low- and high-order streams were often found to be comparable. As a result, the hyporheic zone's intrinsic potential for biogeochemical transformations is comparable across different stream orders, but the greater river miles and larger total streambed area of lower order streams result in the highest cumulative impact from low-order streams. Lateral exchange through meander banks may be important in some cases but generally only in large rivers.

A hydrogeomorphic river network model predicts where and why hyporheic exchange is important in large basins

NASA Astrophysics Data System (ADS)

Gomez-Velez, Jesus D.; Harvey, Judson W.

2014-09-01

Hyporheic exchange has been hypothesized to have basin-scale consequences; however, predictions throughout river networks are limited by available geomorphic and hydrogeologic data and by models that can analyze and aggregate hyporheic exchange flows across large spatial scales. We developed a parsimonious but physically based model of hyporheic flow for application in large river basins: Networks with EXchange and Subsurface Storage (NEXSS). We applied NEXSS across a broad range of geomorphic diversity in river reaches and synthetic river networks. NEXSS demonstrates that vertical exchange beneath submerged bed forms rather than lateral exchange through meanders dominates hyporheic fluxes and turnover rates along river corridors. Per kilometer, low-order streams have a biogeochemical potential at least 2 orders of magnitude larger than higher-order streams. However, when biogeochemical potential is examined per average length of each stream order, low- and high-order streams were often found to be comparable. As a result, the hyporheic zone's intrinsic potential for biogeochemical transformations is comparable across different stream orders, but the greater river miles and larger total streambed area of lower order streams result in the highest cumulative impact from low-order streams. Lateral exchange through meander banks may be important in some cases but generally only in large rivers.

Groundwater controls on river channel pattern

NASA Astrophysics Data System (ADS)

Bätz, Nico; Colombini, Pauline; Cherubini, Paolo; Lane, Stuart N.

2017-04-01

Braided rivers are characterized by high rates of morphological change. However, despite the potential for frequent disturbance, vegetated patches may develop within this system and influence long-term channel dynamics and channel patterns through the "engineering effects" of vegetation. The stabilizing effect of developing vegetation on morphological change has been widely shown by flume experiments and (historic) aerial pictures analysis. Thus, there is a balance between disturbance and stabilization, mediated through vegetation, that may determine the long-term geomorphic and biogeomorphic evolution of the river. It follows that with a change in disturbance frequency relative to the rate of vegetation establishment, a systematic geomorphological shift could occur. Research has addressed how changes in disturbance frequency affect river channel pattern, but has rarely addressed the way in which the stabilizing effects of biogeomorphic succession interact with disturbance frequency to maintain a river in a more dynamic or a less dynamic state. Here, we quantify how the interplay between groundwater access, disturbance frequency and vegetation succession, drive changes in channel pattern. We studied this complex interplay on a transitional gravel-bed river system (braided, wandering, meandering) close to Geneva (Switzerland) - the Allondon River. Dendroecological analysis demonstrate that vegetation growth is driven by groundwater access. Groundwater access conditions the rate of vegetation stabilization at the sub-reach scale and, due to a reduction in flood-related disturbance frequency over the last 50 years, drives a change in channel pattern. Where groundwater is shallower, vegetation encroachment rates were high and as flood-related disturbance decreased, the river has shifted towards a meandering state. Where groundwater was deeper, vegetation growth was limited by water-access and thus vegetation encroachment rates were low. Even though there was a

Dead fish swimming: a review of research on the early migration and high premature mortality in adult Fraser River sockeye salmon Oncorhynchus nerka.

PubMed

Hinch, S G; Cooke, S J; Farrell, A P; Miller, K M; Lapointe, M; Patterson, D A

2012-07-01

Adult sockeye salmon Oncorhynchus nerka destined for the Fraser River, British Columbia are some of the most economically important populations but changes in the timing of their homeward migration have led to management challenges and conservation concerns. After a directed migration from the open ocean to the coast, this group historically would mill just off shore for 3-6 weeks prior to migrating up the Fraser River. This milling behaviour changed abruptly in 1995 and thereafter, decreasing to only a few days in some years (termed early migration), with dramatic consequences that have necessitated risk-averse management strategies. Early migrating fish consistently suffer extremely high mortality (exceeding 90% in some years) during freshwater migration and on spawning grounds prior to spawning. This synthesis examines multidisciplinary, collaborative research aimed at understanding what triggers early migration, why it results in high mortality, and how fisheries managers can utilize these scientific results. Tissue analyses from thousands of O. nerka captured along their migration trajectory from ocean to spawning grounds, including hundreds that were tracked with biotelemetry, have revealed that early migrants are more reproductively advanced and ill-prepared for osmoregulatory transition upon their entry into fresh water. Gene array profiles indicate that many early migrants are also immunocompromised and stressed, carrying a genomic profile consistent with a viral infection. The causes of these physiological changes are still under investigation. Early migration brings O. nerka into the river when it is 3-6° C warmer than historical norms, which for some late-run populations approaches or exceeds their critical maxima leading to the collapse of metabolic and cardiac scope, and mortality. As peak spawning dates have not changed, the surviving early migrants tend to mill in warm lakes near to spawning areas. These results in the accumulation of many more

The persistence and characteristics of Chinook salmon migrations to the Upper Klamath River prior to exclusion by dams

USGS Publications Warehouse

Hamilton, John B; Rondorf, Dennis W.; Tinniswood, William; Leary, Ryan J; Mayer, Tim; Gavette, Charleen; Casal, Lynne A.

2016-01-01

In this research article, John Hamilton and his co-authors present extensive new research and information gathered since a 2005 publication on the historical evidence of anadromomous fish distribution in the Upper Klamath River watershed. Using historical accounts from early explorers and ethnographers to early-twentieth-century photographs, newspaper accounts, and government reports, the authors provide a more complete record of past salmon migrations. The updated record “substantiate[s] the historical persistence of salmon, their migration characteristics, and the broad population baseline that will be key to future commercial, recreational, and Tribal fisheries in the Klamath River and beyond.” During a time when salmon restoration plans are being considered in the region, the historical record can serve as guidance to once again establish diverse and thriving populations.

Competing growth processes induced by next-nearest-neighbor interactions: Effects on meandering wavelength and stiffness

NASA Astrophysics Data System (ADS)

Blel, Sonia; Hamouda, Ajmi BH.; Mahjoub, B.; Einstein, T. L.

2017-02-01

In this paper we explore the meandering instability of vicinal steps with a kinetic Monte Carlo simulations (kMC) model including the attractive next-nearest-neighbor (NNN) interactions. kMC simulations show that increase of the NNN interaction strength leads to considerable reduction of the meandering wavelength and to weaker dependence of the wavelength on the deposition rate F. The dependences of the meandering wavelength on the temperature and the deposition rate obtained with simulations are in good quantitative agreement with the experimental result on the meandering instability of Cu(0 2 24) [T. Maroutian et al., Phys. Rev. B 64, 165401 (2001), 10.1103/PhysRevB.64.165401]. The effective step stiffness is found to depend not only on the strength of NNN interactions and the Ehrlich-Schwoebel barrier, but also on F. We argue that attractive NNN interactions intensify the incorporation of adatoms at step edges and enhance step roughening. Competition between NNN and nearest-neighbor interactions results in an alternative form of meandering instability which we call "roughening-limited" growth, rather than attachment-detachment-limited growth that governs the Bales-Zangwill instability. The computed effective wavelength and the effective stiffness behave as λeff˜F-q and β˜eff˜F-p , respectively, with q ≈p /2 .

River self-organisation inhibits discharge control on waterfall migration.

PubMed

Baynes, Edwin R C; Lague, Dimitri; Attal, Mikaël; Gangloff, Aurélien; Kirstein, Linda A; Dugmore, Andrew J

2018-02-05

The action of rivers within valleys is fundamentally important in controlling landscape morphology, and how it responds to tectonic or climate change. The response of landscapes to external forcing usually results in sequential changes to river long profiles and the upstream migration of waterfalls. Currently, models of this response assume a relationship between waterfall retreat rate and drainage area at the location of the waterfall. Using an experimental study, we show that this assumption has limited application. Due to a self-regulatory response of channel geometry to higher discharge through increasing channel width, the bed shear stress at the lip of the experimental waterfall remains almost constant, so there was no observed change in the upstream retreat rate despite an order of magnitude increase in discharge. Crucially, however, the strength of the bedrock material exhibits a clear control on the magnitude of the mean retreat rate, highlighting the importance of lithology in setting the rate at which landscapes respond to external forcing. As a result existing numerical models of landscape evolution that simulate the retreat of waterfalls as a function of drainage area with a fixed erodibility constant should be re-evaluated to consider spatial heterogeneity in erodibility and channel self-organisation.

The use of historical maps for reconstructing landforms before river damming. The case of the Swiss Rhone River

NASA Astrophysics Data System (ADS)

Reynard, E.; Laigre, L.; Baud, D.

2012-04-01

The Swiss Rhone River was systematically embanked during the period 1864-1893. The Swiss Rhone River valley is a glacial valley filled by glaciolacustrine, fluvioglacial and fluvial sediments. Torrential tributaries contribute to a large extent to the sedimentation in the valley and have built large alluvial fans in the main valley. The period before the river damming corresponds to the Little Ice Age, and it is supposed that the torrential behaviour of the river and its tributaries was very active during that period. In parallel to a large hydraulic project (Third Rhone River Correction), aiming at enlarging the river for security and environmental reasons, this project aims at reconstructing the palaeogeomorphology of the river floodplain before and also during the 30-year long embankment project developed during the last decades of the 19th century. The objective is to better know the geomorphological behaviour of the river, and also to localize palaolandforms (meanders, braided patterns, sandstone dunes, wetlands, etc.), present in the floodplain in the first part of the 19th century and that have now totally disappeared. The project is carried out in close collaboration with the Cantonal Archives of Valais and with a group of historians working on the relations between the river and the communities. It should contribute to a better knowledge of the Swiss Rhone River history (Reynard et al., 2009). Both published official maps (Dufour maps, Siegfried maps) and unpublished maps and plans are systematically collected, digitized, and organised in a database managed by a Geographical Information System. Other data are collected (place names, geomorphological, hydrological and hydraulic data, information about land-use and vegetation, paintings and photographs, etc.) and localised. A high-resolution digital terrain model and areal photographs are also used and allow us to map palaeolandforms (meanders, filled oxbow lakes, former channels, etc.). In a second step

Absolute and convective instabilities and their roles in the forecasting of large frontal meanderings

NASA Astrophysics Data System (ADS)

Liang, X. San; Robinson, Allan R.

2013-10-01

Frontal meanderings are generally difficult to predict. In this study, we demonstrate through an exercise with the Iceland-Faeroe Front (IFF) that satisfactory predictions may be achieved with the aid of hydrodynamic instability analysis. As discovered earlier on, underlying the IFF meandering is a convective instability in the western boundary region followed by an absolute instability in the interior; correspondingly the disturbance growth reveals a switch of pattern from spatial amplification to temporal amplification. To successfully forecast the meandering, the two instability processes must be faithfully reproduced. This sets stringent constraints for the tunable model parameters, e.g., boundary relaxation, temporal relaxation, eddy diffusivity, etc. By analyzing the instability dispersion properties, these parameters can be rather accurately set and their respective ranges of sensitivity estimated. It is shown that too much relaxation inhibits the front from varying; on the other hand, too little relaxation may have the model completely skip the spatial growth phase, leading to a meandering way more upstream along the front. Generally speaking, dissipation/diffusion tends to stabilize the simulation, but unrealistically large dissipation/diffusion could trigger a spurious absolute instability, and hence a premature meandering intrusion. The belief that taking in more data will improve the forecast does not need to be true; it depends on whether the model setup admits the two instabilities. This study may help relieve modelers from the laborious and tedious work of parameter tuning; it also provides us criteria to distinguish a physically relevant forecast from numerical artifacts.

Maximum outer-bank velocity reduction for vane-dike fields installed in channel bends

Treesearch

S. Michael Scurlock; Amanda L. Cox; Christopher I. Thornton; Drew C. Baird

2011-01-01

Hydraulic conditions associated with channel bends in meandering rivers include secondary, helical currents, mass shift of flow to the outside of the bend, and increased erosion along the outer streambank. Such outer-bank erosion may result in undesired plan-form migration of the stream course, placing valuable land holdings or infrastructure in jeopardy. A type of in-...

Development of an analytical Lagrangian model for passive scalar dispersion in low-wind speed meandering conditions

NASA Astrophysics Data System (ADS)

Stefanello, M. B.; Degrazia, G. A.; Mortarini, L.; Buligon, L.; Maldaner, S.; Carvalho, J. C.; Acevedo, O. C.; Martins, L. G. N.; Anfossi, D.; Buriol, C.; Roberti, D.

2018-02-01

Describing the effects of wind meandering motions on the dispersion of scalars is a challenging task, since this type of flow represents a physical state characterized by multiple scales. In this study, a Lagrangian stochastic diffusion model is derived to describe scalar transport during the horizontal wind meandering phenomenon that occurs within a planetary boundary layer. The model is derived from the linearization of the Langevin equation, and it employs a heuristic functional form that represents the autocorrelation function of meandering motion. The new solutions, which describe the longitudinal and lateral wind components, were used to simulate tracer experiments that were performed in low-wind speed conditions. The results of the comparison indicate that the new model can effectively reproduce the observed concentrations of the contaminants, and therefore, it can satisfactorily describe enhanced dispersion effects due to the presence of meandering.

Migration delays caused by anthropogenic barriers: modeling dams, temperature, and success on migrating salmon smolts

USGS Publications Warehouse

Marschall, Elizabeth A.; Mather, Martha E.; Parrish, Donna; Allison, Gary W.; McMenemy, James R.

2011-01-01

Disruption to migration is a growing problem for conservation and restoration of animal populations. Anthropogenic barriers along migration paths can delay or prolong migrations, which may result in a mismatch with migration-timing adaptations. To understand the interaction of dams (as barriers along a migration path), seasonally changing environmental conditions, timing of Atlantic salmon (Salmo salar) downstream migration, and ultimate migration success, we used 10 years of river temperature and discharge data as a template upon which we simulated downstream movement of salmon. Atlantic salmon is a cool-water species whose downstream migrating smolts must complete migration before river temperatures become too warm. We found that dams had a local effect on survival as well as a survival effect that was spatially and temporally removed from the encounter with the dam. While smolts are delayed by dams, temperatures downstream can reach lethal or near-lethal temperatures; as a result, the match between completion of migration and the window of appropriate migration conditions can be disrupted. The strength of this spatially and temporally removed effect is at least comparable to the local effects of dams in determining smolt migration success in the presence of dams. We also considered smolts from different tributaries, varying in distance from the river mouth, to assess the potential importance of locally adapted migration timing on the effect of barriers. Migration-initiation temperature affected modeled smolt survival differentially across tributaries, with the success of smolts from upstream tributaries being much more variable across years than that of smolts with a shorter distance to travel. As a whole, these results point to the importance of broadening our spatial and temporal view when managing migrating populations. We must consider not only how many individuals never make it across migration barriers, but also the spatially and temporally removed

Spatial-temporal fluvial morphology analysis in the Quelite river: It's impact on communication systems

NASA Astrophysics Data System (ADS)

Ramos, Judith; Gracia, Jesús

2012-01-01

SummaryDuring 2008 and 2009 heavy rainfall took place around the Mazatlan County in the Sinaloa state, Mexico, with a return period (Tr) between 50 and 100 years. As a result, the region and its infrastructure, such as the railways and highways (designed for a Tr = 20 years) were severely exposed to floods and, as a consequence damage caused by debris and sediments dragged into the channel. One of the highest levels of damage to the infrastructure was observed in the columns of Quelite River railway's bridge. This is catastrophic as the railway is very important for trade within the state and also among other states in Mexico and in the USA. In order to understand the impact of the flooding and to avoid the rail system being damaged it is necessary to analyse how significant the changes in the river channel have been. This analysis looks at the definition of the main channel and its floodplain as a result of the sediment variability, not only at the bridge area, but also upstream and downstream. The Quelite River study considers the integration of Geographic Information Systems (GIS) and remote sensing data to map, recognise and assess the spatio-temporal change channel morphology. This increases the effectiveness of using different types of geospatial data with in situ measurements such as hydrological data. Thus, this paper is an assessment of a 20 years study period carried out using historical Landsat images and aerial photographs as well as recent Spot images. A Digital Elevation Model (DEM) of local topography and flow volumes were also used. The results show the Quelite River is an active river with a high suspended sediment load and migration of meanders associated to heavy rainfall. The river also has several deep alluvial floodplain channels which modified the geometry and other morphological characteristics of the channel in the downstream direction. After the identification of the channel changes, their causes and solutions to control, the channel

Survival Estimates for the Passage of Spring-Migrating Juvenile Salmonids through Snake and Columbia River Dams and Reservoirs, 2003-2004 Annual Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Steven G.; Muir, William D.; Zabel, Richard W.

2004-01-01

For juvenile chinook salmon Oncorhynchus tshawytscha, sockeye salmon O. nerka, and steelhead O. mykiss that migrate through reservoirs, hydroelectric projects, and free-flowing sections of the Snake and Columbia Rivers, survival estimates are essential to develop effective strategies for recovering depressed stocks. Many management strategies were based on estimates of system survival (Raymond 1979; Sims and Ossiander 1981) derived in a river system considerably different from today's (Williams and Matthews 1995; Williams et al. 2001). Knowledge of the magnitude, locations, and causes of smolt mortality under present passage conditions, and under conditions projected for the future, are necessary to develop strategiesmore » that will optimize smolt survival during migration. From 1993 through 2002, the National Marine Fisheries Service (NMFS) and the University of Washington (UW) demonstrated the feasibility of using three statistical models to estimate survival of PIT-tagged (Prentice et al. 1990a) juvenile salmonids passing through Snake River dams and reservoirs (Iwamoto et al. 1994; Muir et al. 1995, 1996, 2001a, 2003; Smith et al. 1998, 2000a,b; Hockersmith et al. 1999; Zabel et al. 2001, 2002). Evaluation of assumptions for these models indicated that all were generally satisfied, and accurate and precise survival estimates were obtained. In 2003, NMFS and UW completed the eleventh year of the study. Flow levels during the early portion of the 2003 spring migration were similar to 2002, and only slightly higher than in the drought conditions during 2001. However, flow levels were much greater during the later part of the migration in 2003. Spill levels were similar to 2002, much higher than in 2001. Research objectives were to: (1) estimate reach survival and travel time in the Snake and Columbia Rivers throughout the yearling chinook salmon and steelhead migrations; (2) evaluate relationships between survival estimates and migration conditions; and (3

The effect of bedload transport rates on bedform and planform morphological development in a laboratory meandering stream under varying flow conditions

NASA Astrophysics Data System (ADS)

Sullivan, C.; Good, R. G. R.; Binns, A. D.

2017-12-01

Sediment transport processes in streams provides valuable insight into the temporal evolution of planform and bedform geometry. The majority of previous experimental research in the literature has focused on bedload transport and corresponding bedform development in rectangular, confined channels, which does not consider planform adjustment processes in streams. In contrast, research conducted with laboratory streams having movable banks can investigate planform development in addition to bedform development, which is more representative of natural streams. The goal of this research is to explore the relationship between bedload transport rates and the morphological adjustments in meandering streams. To accomplish this, a series of experimental runs were conducted in a 5.6 m by 1.9 m river basin flume at the University of Guelph to analyze the bedload impacts on bed formations and planform adjustments in response to varying flow conditions. In total, three experimental runs were conducted: two runs using steady state conditions and one run using unsteady flow conditions in the form of a symmetrical hydrograph implementing quasi steady state flow. The runs were performed in a series of time-steps in order to monitor the evolution of the stream morphology and the bedload transport rates. Structure from motion (SfM) was utilized to capture the channel morphology after each time-step, and Agisoft PhotoScan software was used to produce digital elevation models to analyze the morphological evolution of the channel with time. Bedload transport rates were quantified using a sediment catch at the end of the flume. Although total flow volumes were similar for each run, the morphological evolution and bedload transport rates in each run varied. The observed bedload transport rates from the flume are compared with existing bedload transport formulas to assess their accuracy with respect to sediment transport in unconfined meandering channels. The measured sediment transport

Developing Depositional Models for Mercury Contaminated Floodplain Deposits Using Geomorphic Mapping and GIS in South River, Virginia

NASA Astrophysics Data System (ADS)

Barbieri, A.; Pizzuto, J.; O'Neal, M. A.; Rhoades, E.

2007-12-01

Mercury was introduced into the South River from the 1930s to the 1950s from an industrial plant in Waynesboro, Virginia. Mercury contamination in fish tissue continues to exceed acceptable levels. The contaminated sediments in the river's floodplains are probably the present source of mercury to the South River ecosystem. Locating and determining the extent and depositional history of these deposits are important for understanding the mercury cycle in the river as well as for remediation plans. The South River is a sinuous, single thread alluvial river with frequent bedrock exposures along its bed and banks. Overbank deposits are discontinuous and thin. Rates of lateral migration by the South River are extremely low, averaging 0.02 m/yr, and the river has been influenced by mill dams along a 19 km study reach. This 19 km section of the 37 km river reach was selected for the study because of its high concentration of Hg. Six different categories of floodplain deposits dating from 1937-2005 have been identified throughout the river using studies of historical aerial photographs in a GIS framework, field mapping, dendro- and radionuclide dating, grain size and Hg analysis. Not surprisingly, traditional depositional models of meandering rivers do not apply. Floodplain depositional units include mill dam deposits, point bar/bench deposits, concave bank bench deposits, islands, cattle deposits, and tributary confluences deposits. The most important deposits for sequestering historic mercury are those that also store the most silt and clay. These include mill dam deposits, point bar/bench deposits, concave bank deposits, and tributary confluence deposits. Many of these deposits represent reservoirs of mercury-contaminated sediments that could supply significant amounts of mercury into the river presently and in the future.

Hydraulic Characteristics of the Lower Snake River During Periods of Juvenile Fall Chinook Migration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, Chris B.; Dibrani, Berhon; Richmond, Marshall C.

2006-01-30

This report documents a four-year study to assess hydraulic conditions in the lower Snake River. The work was conducted for the Bonneville Power Administration, U.S. Department of Energy, by the Pacific Northwest National Laboratory. Cold water released from the Dworshak Reservoir hypolimnion during mid- to late-summer months cools the Clearwater River far below equilibrium temperature. The volume of released cold water augments the Clearwater River, and the combined total discharge is on the order of the Snake River discharge when the two rivers meet at their confluence near the upstream edge of Lower Granite Reservoir. With typical temperature differences betweenmore » the Clearwater and Snake rivers of 10°C or more during July and August, the density difference between the two rivers during summer flow augmentation periods is sufficient to stratify Lower Granite Reservoir as well as the other three reservoirs downstream. Because cooling of the river is desirable for migrating juvenile fall Chinook salmon (Oncorhynchus tshawytscha) during this same time period, the amount of mixing and cold water entrained into Lower Granite Reservoir’s epilimnion at the Clearwater/Snake River confluence is of key biological importance to juvenile fall Chinook salmon. Data collected during this project indicates the three reservoirs downstream of Lower Granite also stratify as direct result of flow augmentation from Dworshak Reservoir. These four lower Snake reservoirs are also heavily influenced by wind forcing at the water’s surface, and during periods of low river discharge, often behave like a two-layer lake. During these periods of stratification, lower river discharge, and wind forcing, the water in the upper layer of the reservoir is held in place or moves slightly upstream. This upper layer is also exposed to surface heating and may warm up to temperatures close to equilibrium temperature. The depth of this upper warm layer and its direction of travel may also be

Wake meandering statistics of a model wind turbine: Insights gained by large eddy simulations

NASA Astrophysics Data System (ADS)

Foti, Daniel; Yang, Xiaolei; Guala, Michele; Sotiropoulos, Fotis

2016-08-01

Wind tunnel measurements in the wake of an axial flow miniature wind turbine provide evidence of large-scale motions characteristic of wake meandering [Howard et al., Phys. Fluids 27, 075103 (2015), 10.1063/1.4923334]. A numerical investigation of the wake, using immersed boundary large eddy simulations able to account for all geometrical details of the model wind turbine, is presented here to elucidate the three-dimensional structure of the wake and the mechanisms controlling near and far wake instabilities. Similar to the findings of Kang et al. [Kang et al., J. Fluid Mech. 744, 376 (2014), 10.1017/jfm.2014.82], an energetic coherent helical hub vortex is found to form behind the turbine nacelle, which expands radially outward downstream of the turbine and ultimately interacts with the turbine tip shear layer. Starting from the wake meandering filtering used by Howard et al., a three-dimensional spatiotemporal filtering process is developed to reconstruct a three-dimensional meandering profile in the wake of the turbine. The counterwinding hub vortex undergoes a spiral vortex breakdown and the rotational component of the hub vortex persists downstream, contributing to the rotational direction of the wake meandering. Statistical characteristics of the wake meandering profile, along with triple decomposition of the flow field separating the coherent and incoherent turbulent fluctuations, are used to delineate the near and far wake flow structures and their interactions. In the near wake, the nacelle leads to mostly incoherent turbulence, while in the far wake, turbulent coherent structures, especially the azimuthal velocity component, dominate the flow field.

Survival Estimates for the Passage of Spring-Migrating Juvenile Salmonids through Snake and Columbia River Dams and Reservoirs, 2008.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faulkner, James R.; Smith, Steven G.; Muir, William D.

2009-06-23

In 2008, the National Marine Fisheries Service completed the sixteenth year of a study to estimate survival and travel time of juvenile salmonids Oncorhynchus spp. passing through dams and reservoirs on the Snake and Columbia Rivers. All estimates were derived from detections of fish tagged with passive integrated transponder (PIT) tags. We PIT tagged and released a total of 18,565 hatchery steelhead O. mykiss, 15,991 wild steelhead, and 9,714 wild yearling Chinook salmon O. tshawytscha at Lower Granite Dam in the Snake River. In addition, we utilized fish PIT tagged by other agencies at traps and hatcheries upstream from themore » hydropower system and at sites within the hydropower system in both the Snake and Columbia Rivers. These included 122,061 yearling Chinook salmon tagged at Lower Granite Dam for evaluation of latent mortality related to passage through Snake River dams. PIT-tagged smolts were detected at interrogation facilities at Lower Granite, Little Goose, Lower Monumental, Ice Harbor, McNary, John Day, and Bonneville Dams and in the PIT-tag detector trawl operated in the Columbia River estuary. Survival estimates were calculated using a statistical model for tag-recapture data from single release groups (the single-release model). Primary research objectives in 2008 were to: (1) estimate reach survival and travel time in the Snake and Columbia Rivers throughout the migration period of yearling Chinook salmon and steelhead, (2) evaluate relationships between survival estimates and migration conditions, and (3) evaluate the survival estimation models under prevailing conditions. This report provides reach survival and travel time estimates for 2008 for PIT-tagged yearling Chinook salmon (hatchery and wild), hatchery sockeye salmon O. nerka, hatchery coho salmon O. kisutch, and steelhead (hatchery and wild) in the Snake and Columbia Rivers. Additional details on the methodology and statistical models used are provided in previous reports cited here

Floodplain dynamics control the age distribution of organic carbon in large rivers

NASA Astrophysics Data System (ADS)

Torres, M. A.; Limaye, A. B. S.; Ganti, V.; West, A. J.; Fischer, W. W.; Lamb, M. P.

2016-12-01

As sediments transit through river systems, they are temporarily stored within floodplains. This storage is important for geochemical cycles because it imparts a certain cadence to weathering processes and organic carbon cycling. However, the time and length scales over which these processes operate are poorly known. To address this, we developed a model for the distribution of storage times in floodplains and used it to make predictions of the age distribution of riverine particulate organic carbon (POC) that can be compared with data from a range of rivers.Using statistics generated from a numerical model of river meandering that accounts for the rates of lateral channel migration and the lengths of channel needed to exchange the sediment flux with the floodplain, we estimated the distribution of sediment storage times. Importantly, this approach consistently yields a heavy-tailed distribution of storage times. This finding, based on comprehensive simulations of a wide range of river conditions, arises because of geometrical constraints that lead to the preferential erosion and reworking of young deposits. To benchmark our model, we compared our results with meteoric 10Be data (a storage time proxy) from Amazonian rivers. Our model correctly predicts observed 10Be concentrations, and consequently appears to capture the correct characteristic timescales associated with floodplain storage. By coupling a simple model of carbon cycling with our floodplain storage model, we are able to make predictions about the radiocarbon content of riverine POC. We observe that floodplains with greater storage times tend to have biospheric POC with a lower radiocarbon content (after correcting bulk ages for contribution from radiocarbon-dead petrogenic carbon). This result confirms that storage plays a key role in setting the age of POC transported by rivers with important implications for the dynamics of the global carbon cycle.

Divergent migration within lake sturgeon (Acipenser fulvescens) populations: Multiple distinct patterns exist across an unrestricted migration corridor.

PubMed

Kessel, Steven T; Hondorp, Darryl W; Holbrook, Christopher M; Boase, James C; Chiotti, Justin A; Thomas, Michael V; Wills, Todd C; Roseman, Edward F; Drouin, Richard; Krueger, Charles C

2018-01-01

Population structure, distribution, abundance and dispersal arguably underpin the entire field of animal ecology, with consequences for regional species persistence, and provision of ecosystem services. Divergent migration behaviours among individuals or among populations are an important aspect of the ecology of highly mobile animals, allowing populations to exploit spatially or temporally distributed food and space resources. This study investigated the spatial ecology of lake sturgeon (Acipenser fulvescens) within the barrier free Huron-Erie Corridor (HEC), which connects Lake Huron and Lake Erie of the North American Laurentian Great Lakes. Over 6 years (2011-2016), movements of 268 lake sturgeon in the HEC were continuously monitored across the Great Lakes using acoustic telemetry (10 years battery life acoustic transmitters). Five distinct migration behaviours were identified with hierarchical cluster analysis, based on the phenology and duration of river and lake use. Lake sturgeon in the HEC were found to contain a high level of intraspecific divergent migration, including partial migration with the existence of residents. Specific behaviours included year-round river residency and multiple lake-migrant behaviours that involved movements between lakes and rivers. Over 85% of individuals were assigned to migration behaviours as movements were consistently repeated over the study, which suggested migration behaviours were consistent and persistent in lake sturgeon. Differential use of specific rivers or lakes by acoustic-tagged lake sturgeon further subdivided individuals into 14 "contingents" (spatiotemporally segregated subgroups). Contingents associated with one river (Detroit or St. Clair) were rarely detected in the other river, which confirmed that lake sturgeon in the Detroit and St. Clair represent two semi-independent populations that could require separate management consideration for their conservation. The distribution of migration behaviours

Divergent migration within lake sturgeon (Acipenser fulvescens) populations: Multiple distinct patterns exist across an unrestricted migration corridor

USGS Publications Warehouse

Kessel, Steven T.; Hondorp, Darryl W.; Holbrook, Christopher; Boase, James C.; Chiotti, Justin A.; Thomas, Michael V.; Wills, Todd C.; Roseman, Edward; Drouin, Richard; Krueger, Charles C.

2018-01-01

Population structure, distribution, abundance, and dispersal arguably underpin the entire field of animal ecology, with consequences for regional species persistence, and provision of ecosystem services. Divergent migration behaviours among individuals or among populations is an important aspect of the ecology of highly-mobile animals, allowing populations to exploit spatially- or temporally-distributed food and space resources.This study investigated the spatial ecology of lake sturgeon (Acipenser fulvescens) within the barrier free Huron-Erie Corridor (HEC), which connects Lake Huron and Lake Erie of the North American Laurentian Great Lakes.Over six years (2011 – 2016), movements of 268 lake sturgeon in the HEC were continuously monitored across the Great Lakes using acoustic telemetry (10 yr battery life acoustic transmitters). Five distinct migration behaviours were identified with hierarchical cluster analysis, based on the phenology and duration of river and lake use.Lake sturgeon in the HEC were found to contain a high level of intraspecific divergent migration, including partial migration with the existence of residents. Specific behaviours included year-round river residency and multiple lake-migrant behaviours that involved movements between lakes and rivers. Over 85% of individuals were assign to migration behaviours as movements were consistently repeated over the study, which suggested migration behaviours were consistent and persistent in lake sturgeon. Differential use of specific rivers or lakes by acoustic-tagged lake sturgeon further subdivided individuals into 14 “contingents” (spatiotemporally segregated subgroups).Contingents associated with one river (Detroit or St. Clair) were rarely detected in the other river, which confirmed that lake sturgeon in the Detroit and St. Clair represent two semi-independent populations that could require separate management consideration for their conservation. The distribution of migration behaviours

Hydrology, geomorphology, and vegetation of Coastal Plain rivers in the southeastern United States

Treesearch

Cliff R. Hupp

2000-01-01

Rivers of the Coastal Plain of the southeastern United States are characteristically low-gradient meandering systems that develop broad floodplains subjected to frequent and prolonged flooding. These floodplains support a relatively unique forested wetland (Bottomland Hardwoods), which have received considerable ecological study, but distinctly less hydrogeomorphic...

Migration delays caused by anthropogenic barriers: Modeling dams, temperature, and success of migrating salmon smolts

USGS Publications Warehouse

Marschall, E.A.; Mather, M. E.; Parrish, D.L.; Allison, G.W.; McMenemy, J.R.

2011-01-01

Disruption to migration is a growing problem for conservation and restoration of animal populations. Anthropogenic barriers along migration paths can delay or prolong migrations, which may result in a mismatch with migration-timing adaptations. To understand the interaction of dams (as barriers along a migration path), seasonally changing environmental conditions, timing of Atlantic salmon (Salmo salar) downstream migration, and ultimate migration success, we used 10 years of river temperature and discharge data as a template upon which we simulated downstream movement of salmon. Atlantic salmon is a cool-water species whose downstream migrating smolts must complete migration before river temperatures become too warm. We found that dams had a local effect on survival as well as a survival effect that was spatially and temporally removed from the encounter with the dam. While smolts are delayed by dams, temperatures downstream can reach lethal or near-lethal temperatures;as a result, the match between completion of migration and the window of appropriate migration conditions can be disrupted. The strength of this spatially and temporally removed effect is at least comparable to the local effects of dams in determining smolt migration success in the presence of dams. We also considered smolts from different tributaries, varying in distance from the river mouth, to assess the potential importance of locally adapted migration timing on the effect of barriers. Migration-initiation temperature affected modeled smolt survival differentially across tributaries, with the success of smolts from upstream tributaries being much more variable across years than that of smolts with a shorter distance to travel. As a whole, these results point to the importance of broadening our spatial and temporal view when managing migrating populations. We must consider not only how many individuals never make it across migration barriers, but also the spatially and temporally removed

Degree of contamination and sources of polychlorinated biphenyls in Meandering Road Creek and Woods Inlet of Lake Worth, Fort Worth, Texas, 2004 and 2006-07

USGS Publications Warehouse

Braun, Christopher L.; Wilson, Jennifer T.; Van Metre, Peter C.

2008-01-01

Lake Worth is a reservoir on the West Fork Trinity River on the western edge of Fort Worth, Texas. Air Force Plant 4 (AFP4) is on the eastern shore of Woods Inlet, an arm of Lake Worth that extends south from the main body of the lake. Two previous reports documented ele-vated polychlorinated biphenyl (PCB) concentrations in surficial sediment in Woods Inlet relative to those in surficial sediment in other parts of Lake Worth. This report presents the results of another USGS study, done in cooperation with the U.S. Air Force, to indicate the degree of PCB contamination of Meandering Road Creek and Woods Inlet and to identify possible sources of PCBs in Meandering Road Creek and Woods Inlet on the basis of suspended, streambed, and lake-bottom sediment samples collected there in 2004 and 2006-07. About 40 to 80 percent of total PCB concentrations (depending on how total PCB concentration is computed) in suspended sediment exceed the threshold effect concentration, a concentration below which adverse effects to benthic biota rarely occur. About 20 percent of total PCB concentrations (computed as sum of three Aroclors) in suspended sediment exceed the probable effect concentration, a concentration above which adverse effects to benthic biota are expected to occur frequently. About 20 to 30 percent of total PCB concentrations in streambed sediment exceed the threshold effect concentration; and about 6 to 20 percent of total PCB concentrations in lake-bottom (Woods Inlet) sediment exceed the threshold effect concentration. No streambed or lake-bottom sediment concentrations exceed the probable effect concentration. The sources of PCBs to Meandering Road Creek and Woods Inlet were investigated by comparing the relative distributions of PCB congeners of suspended sediment to those of streambed and lake-bottom sediment. The sources of PCBs were identified using graphical analysis of normalized concentrations (congener ratios) of 11 congeners. For graphical analysis, the

A systematic overview of the coincidences of river sinuosity changes and tectonically active structures in the Pannonian Basin

NASA Astrophysics Data System (ADS)

Petrovszki, Judit; Székely, Balázs; Timár, Gábor

2012-12-01

As tectonic movements change the valley slope (low-gradient reaches of valleys, in sedimentary basins), the alluvial rivers, as sensitive indicators, respond to these changes, by varying their courses to accommodate this forcing. In our study sinuosity values, a commonly used characteristic parameter to detect river pattern changes, were studied for the major rivers in the Pannonian Basin in order to reveal neotectonic influence on their planform shape. Our study area comprises the entire Pannonian Basin (330,000 km2) located in eastern Central-Europe, bounded by the Alps, Carpathians and Dinarides. The studied rivers were mostly in their natural meandering state before the main river regulations of the 19th century. The last quasi-natural, non-regulated river planforms were surveyed somewhat earlier, during the Second Military Survey of the Habsburg Empire. Using the digitized river sections of that survey, the sinuosities of the rivers were calculated with different sample section sizes ranging from 5 km to 80 km. Depending on the bank-full discharge, also a 'most representative' section size is given, which can be connected to the neotectonic activity. In total, the meandering reaches of 28 rivers were studied; their combined length is 7406 km. The places where the river sinuosity changed were compared to the structural lines of the "Atlas of the present-day geodynamics of the Pannonian Basin" (Horváth et al., 2006). 36 junctions along 26 structural lines were identified where the fault lines of this neotectonic map crossed the rivers. Across these points the mean sinuosity changed. Depending on the direction of the relative vertical movements, the sinuosity values increased or decreased. There were some points, where the sinuosity changed in an opposite way. Along these sections, the rivers belong to the range of unorganized meandering or there are lithological margins. Assuming that the rivers indicate on-going faulting accurately, some places were found

Experimental Research on Boundary Shear Stress in Typical Meandering Channel

NASA Astrophysics Data System (ADS)

Chen, Kai-hua; Xia, Yun-feng; Zhang, Shi-zhao; Wen, Yun-cheng; Xu, Hua

2018-06-01

A novel instrument named Micro-Electro-Mechanical System (MEMS) flexible hot-film shear stress sensor was used to study the boundary shear stress distribution in the generalized natural meandering open channel, and the mean sidewall shear stress distribution along the meandering channel, and the lateral boundary shear stress distribution in the typical cross-section of the meandering channel was analysed. Based on the measurement of the boundary shear stress, a semi-empirical semi-theoretical computing approach of the boundary shear stress was derived including the effects of the secondary flow, sidewall roughness factor, eddy viscosity and the additional Reynolds stress, and more importantly, for the first time, it combined the effects of the cross-section central angle and the Reynolds number into the expressions. Afterwards, a comparison between the previous research and this study was developed. Following the result, we found that the semi-empirical semi-theoretical boundary shear stress distribution algorithm can predict the boundary shear stress distribution precisely. Finally, a single factor analysis was conducted on the relationship between the average sidewall shear stress on the convex and concave bank and the flow rate, water depth, slope ratio, or the cross-section central angle of the open channel bend. The functional relationship with each of the above factors was established, and then the distance from the location of the extreme sidewall shear stress to the bottom of the open channel was deduced based on the statistical theory.

The effects of river impoundment and hatchery rearing on the migration behavior of juvenile steelhead in the Lower Snake River, Washington

USGS Publications Warehouse

Plumb, J.M.; Perry, R.W.; Adams, N.S.; Rondorf, D.W.

2006-01-01

We used radiotelemetry to monitor the migration behavior of juvenile hatchery and wild steelhead Oncorhynchus mykiss as they migrated through Lower Granite Reservoir and Dam on the lower Snake River, Washington. From 1996 to 2001, we surgically implanted radio transmitters in 1,540 hatchery steelhead and 1,346 wild steelhead. For analysis, we used the inverse Gaussian distribution to describe travel time distributions for cohorts (>50 fish) of juvenile steelhead as they migrated downriver. Mean travel rates were significantly related to reach- and discharge-specific water velocities. Also, mean travel rates near the dam were slower for a given range of water velocities than were mean travel rates through the reservoir, indicating that the presence of the dam caused delay to juvenile steelhead over and above the effect of water velocity. Hatchery steelhead took about twice as long as wild steelhead to pass the dam as a result of the higher proportions of hatchery steelhead traveling upriver from the dam. Because upriver travel and the resulting migration delay might decrease survival, it is possible that hatchery steelhead survive at lower rates than wild steelhead. Our analysis identified a discharge threshold (???2,400 m3/s) below which travel time and the percentage of fish traveling upriver from the dam increased rapidly, providing support for the use of minimum flow targets to mitigate for fish delay and possibly enhance juvenile steelhead survival.

Geomorphic changes resulting from floods in reconfigured gravel-bed river channels in Colorado, USA

USGS Publications Warehouse

Elliott, J.G.; Capesius, J.P.

2009-01-01

Geomorphic changes in reconfi gured reaches of three Colorado rivers in response to floods in 2005 provide a benchmark for "restoration" assessment. Sedimententrainment potential is expressed as the ratio of the shear stress from the 2 yr, 5 yr, 10 yr, and 2005 floods to the critical shear stress for sediment. Some observed response was explained by the excess of flood shear stress relative to the resisting force of the sediment. Bed-load entrainment in the Uncompahgre River and the North Fork Gunnison River, during 4 and 6 yr floods respectively, resulted in streambed scour, streambed deposition, lateral-bar accretion, and channel migration at various locations. Some constructed boulder and log structures failed because of high rates of bank erosion or bed-material deposition. The Lake Fork showed little or no net change after the 2005 flood; however, this channel had not conveyed floods greater than the 2.5 yr flood since reconfi guration. Channel slope and the 2 yr flood, a surrogate for bankfull discharge, from all three reconfi gured reaches plotted above the Leopold and Wolman channel-pattern threshold in the "braided channel" region, indicating that braiding, rather than a single-thread meandering channel, and midchannel bar formation may be the natural tendency of these gravel-bed reaches. When plotted against a total stream-power and median-sediment-size threshold for the 2 yr flood, however, the Lake Fork plotted in the "single-thread channel" region, the North Fork Gunnison plotted in the " multiplethread" region, and the Uncompahgre River plotted on the threshold. All three rivers plotted in the multiple-thread region for floods of 5 yr recurrence or greater. ?? 2009 Geological Society of America.

Gene expression profiling and environmental contaminant assessment of migrating Pacific salmon in the Fraser River watershed of British Columbia.

PubMed

Veldhoen, Nik; Ikonomou, Michael G; Dubetz, Cory; Macpherson, Nancy; Sampson, Tracy; Kelly, Barry C; Helbing, Caren C

2010-05-05

The health and physiological condition of anadromous salmon is of concern as their upriver migration requires navigation of human-impacted waterways and metabolism of stored energy reserves containing anthropogenic contaminants. Such factors may affect reproductive success of fish stocks. This study investigates chemical contaminant burdens and select gene expression profiles in Pacific Sockeye (Oncorhynchus nerka) and Chinook (Oncorhynchus tshawytscha) salmon which traverse the Fraser River watershed during their spawning migration. Chemical analyses of muscle tissue and eggs of salmon collected from the lower Fraser River (pre-migration) and from upstream spawning grounds (post-migration) during the 2007 migration revealed the presence of numerous chemical contaminants, including PCBs, dioxins/furans, pesticides, and heavy metals. However, muscle tissue residue concentrations were well below human health consumption guidelines and 2,3,7,8 TCDD toxic equivalents (SigmaTEQs) in salmon eggs, calculated using WHO toxic equivalency factors (WHO-TEFs) for fish health, did not exceed the 0.3pgg(-1) wet weight toxicological threshold level previously associated with 30% egg mortality in salmon populations. Quantitative real-time PCR probes were generated and used to assess differences in abundance of key mRNA transcripts encoding nine gene products associated with reproduction, stress, metal toxicity, and exposure to environmental contaminants. Gene expression profiles were characterized in liver and muscle tissue of pre- and post-migration Sockeye and Chinook salmon. The results of stock-matched animals indicate that dynamic changes in mRNA levels occur for a number of genes in both species during migration and suggest that Sockeye salmon exhibit a greater level of biological stress compared to the Chinook salmon population. Using a male-specific genotypic marker, we found that out of the 154 animals examined, one Sockeye was genotypically male but phenotypically female

Two Late Pleistocene climate-driven incision/aggradation rhythms in the middle Dnieper River basin, west-central Russian Plain

NASA Astrophysics Data System (ADS)

Panin, Andrei; Adamiec, Grzegorz; Buylaert, Jan-Pieter; Matlakhova, Ekaterina; Moska, Piotr; Novenko, Elena

2017-06-01

In valleys of the River Seim and its tributaries in the middle Dnieper basin (west-central Russian Plain), two low terraces (T1, 10-16 m, and T0, 5-7 m above the river) and a floodplain (2-4 m) with characteristic large and small palaeochannels exist. A range of field and laboratory techniques was applied and ∼30 new numerical ages (OSL and 14C dates) were obtained to establish a chronology of incision and aggradation events that resulted in the current valley morphology. Two full incision/aggradation rhythms and one additional aggradation phase from the previous rhythm were recognized in the Late Pleistocene - Holocene climate cycle. The following events were detected. (1) Late MIS 5 - early MIS 4: aggradation of Terrace T1 following the deep incision at the end of MIS 6. (2) Late MIS 4 (40-30 ka): incision into Terrace T1 below the present-day river, formation of the main scarp in the bottom of the valley between Terrace T1 and Terrace T0/Floodplain levels. (3) MIS 2: aggradation of Terrace T0, lateral migrations of a shallow braided channel located few meters above the present-day river since ∼25 ka through the LGM. (4) 18-13 ka: incision into Terrace T0 below the modern river. Multiple-thread channels concentrated in a single flow that at some places formed large meanders. In the period 15-13 ka, high floods that rose above the present-day floods left large levees and overbank loams on Terrace T0. (5) Younger Dryas - Holocene transition: aggradation up to the modern channel level, transformation of large Late Glacial to small Holocene meanders. The established incision/aggradation rhythms are believed to be manifested over the Central Russian Plain outside the influence of ice sheets in the north and base level changes in the south. The two-phase deepening of the valley occurred in the last quarter of the last glacial epoch but can not be attributed directly to the glacial-interglacial transition. Both the detected incision events correspond to relatively

Steering cell migration by alternating blebs and actin-rich protrusions.

PubMed

Diz-Muñoz, Alba; Romanczuk, Pawel; Yu, Weimiao; Bergert, Martin; Ivanovitch, Kenzo; Salbreux, Guillaume; Heisenberg, Carl-Philipp; Paluch, Ewa K

2016-09-02

High directional persistence is often assumed to enhance the efficiency of chemotactic migration. Yet, cells in vivo usually display meandering trajectories with relatively low directional persistence, and the control and function of directional persistence during cell migration in three-dimensional environments are poorly understood. Here, we use mesendoderm progenitors migrating during zebrafish gastrulation as a model system to investigate the control of directional persistence during migration in vivo. We show that progenitor cells alternate persistent run phases with tumble phases that result in cell reorientation. Runs are characterized by the formation of directed actin-rich protrusions and tumbles by enhanced blebbing. Increasing the proportion of actin-rich protrusions or blebs leads to longer or shorter run phases, respectively. Importantly, both reducing and increasing run phases result in larger spatial dispersion of the cells, indicative of reduced migration precision. A physical model quantitatively recapitulating the migratory behavior of mesendoderm progenitors indicates that the ratio of tumbling to run times, and thus the specific degree of directional persistence of migration, are critical for optimizing migration precision. Together, our experiments and model provide mechanistic insight into the control of migration directionality for cells moving in three-dimensional environments that combine different protrusion types, whereby the proportion of blebs to actin-rich protrusions determines the directional persistence and precision of movement by regulating the ratio of tumbling to run times.

Mechanical Stress Effects on Electromigration Voiding in a Meandering Test Stripe

NASA Technical Reports Server (NTRS)

Lowry, L. E.; Tai, B. H.; Mattila, J.; Walsh, L. H.

1993-01-01

Earlier experimental findings concluded that electromigratin voids in these meandering stripe test structures were not randomly distributed and that void nucleation frequenly occurred sub-surface at the metal/thermal oxide interface.

Vegetative impacts upon bedload transport capacity and channel stability for differing alluvial planforms in the Yellow River source zone

NASA Astrophysics Data System (ADS)

Li, Zhi Wei; Yu, Guo An; Brierley, Gary; Wang, Zhao Yin

2016-07-01

The influence of vegetation upon bedload transport and channel morphodynamics is examined along a channel stability gradient ranging from meandering to anabranching to anabranching-braided to fully braided planform conditions along trunk and tributary reaches of the Upper Yellow River in western China. Although the regional geology and climate are relatively consistent across the study area, there is a distinct gradient in the presence and abundance of riparian vegetation for these reaches atop the Qinghai-Tibet Plateau (elevations in the study area range from 2800 to 3400 m a.s.l.). To date, the influence of vegetative impacts upon channel planform and bedload transport capacity of alluvial reaches of the Upper Yellow River remains unclear because of a lack of hydrological and field data. In this region, the types and pattern of riparian vegetation vary with planform type as follows: trees exert the strongest influence in the anabranching reach, the meandering reach flows through meadow vegetation, the anabranching-braided reach has a grass, herb, and sparse shrub cover, and the braided reach has no riparian vegetation. A non-linear relation between vegetative cover on the valley floor and bedload transport capacity is evident, wherein bedload transport capacity is the highest for the anabranching reach, roughly followed by the anabranching-braided, braided, and meandering reaches. The relationship between the bedload transport capacity of a reach and sediment supply from upstream exerts a significant influence upon channel stability. Bedload transport capacity during the flood season (June-September) in the braided reach is much less than the rate of sediment supply, inducing bed aggradation and dynamic channel adjustments. Rates of channel adjustment are less pronounced for the anabranching-braided and anabranching reaches, while the meandering reach is relatively stable (i.e., this is a passive meandering reach).

Sinuosity change of the Po River near Cremona (Northern Italy) - a result of neotectonic activity?

NASA Astrophysics Data System (ADS)

Petrovszki, Judit; Timár, Gábor

2010-05-01

In the map sheets of the Second Military Survey of the Habsburg Empire, Lombardia, Parma, Modena and Venice also can be seen (Timár et al., 2006). This area was surveyed between 1818 and 1829. In these map sheets, we can also follow the river Po from Vaccarizza to the delta. This river reach is about 350 km long. This river reach was digitized and sinuosity values were calculated with different window sizes, and displayed in a spectrum-like diagram (sinuosity spectra; after van Balen et al., 2008). At Cremona, a significante sinuosity change were identified. The sinuosity increasing, and we have high sinuosity values. In the summarizing geological map of Italy (Compagnoni and Calluzzo, 2004), at this place, a tectonic line was identified. So probably this fault line invokes the sinuosity change on the river. The vertical movements indicated on the maps are just the opposite like they would be according to the flume experiments of Ouchi (1985). In the case of the Po River at Cremona, the decrease of the channel slope results higher sinuosity. The reason is that the rate of the slope and water discharge is higher than it is required by the self-organized meandering and the river parameters fell to the range of the unorganized meandering (cf. Timár, 2003). Another possible explanation could be that the northern tributary, the Adda River has significant sediment load that lowers the sinuosity of the trunk river at the confluence. Compagnoni, B., Galluzzo, F. (eds., 2004): Geological Map of Italy. Agenzia per la Protezione dell'Ambiente per I Servizi Tecnici - Dipartimento Difesa del Suolo, Servizio Geologico d'Italia, Rome-Florence-Genoa. Map, scale=1:1250000, especially printed for the 32nd International Geological Congress. Ouchi, S. (1985): Response of alluvial rivers to slow active tectonic movement. Geol. Soc. Am. Bull. 96: 504-515. Timár, G. (2003): Controls on channel sinuosity changes: a case study of the Tisza River, the Great Hungarian Plain. Quaternary

76 FR 63951 - Notice of Filing of Plats of Survey; Montana

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-14

... meanders of the former left bank of the Tongue River, downstream, through sections 27, 28, and 29, and the adjusted original meanders of the former right bank of the Tongue River, downstream, through sections 21... Tongue River, downstream, through sections 27 and 28, and a portion of section 29, the meanders of the...

The internal strength of rivers: autogenic processes in control of the sediment load (Tana River, Kenya)

NASA Astrophysics Data System (ADS)

Geeraert, Naomi; Ochieng Omengo, Fred; Tamooh, Fredrick; Paron, Paolo; Bouillon, Steven; Govers, Gerard

2014-05-01

mobilised within the river during a given event travels slower than the water. The highly dynamic behaviour of the river is further demonstrated by the rapid changes in river cross-section at Garissa and meander migration rates of several m y-1. In order to estimate a time frame for which changes in sediment inputs will be reflected in the sediment concentration at Garissa a single box model was developed. Results indicate that the effects of sediment blockage by the dams will only be visible after several hundreds to perhaps thousands of years. This clearly shows that autogenic processes are dominant in the lower Tana River and that, therefore, changes in sediment delivery cannot be detected in the sediment discharge record. More generally, understanding and interpreting the dynamics of such river systems requires that autogenic processes are correctly accounted for.

Life history migrations of adult Yellowstone Cutthroat Trout in the upper Yellowstone River

USGS Publications Warehouse

Ertel, Brian D.; McMahon, Thomas E.; Koel, Todd M.; Gresswell, Robert E.; Burckhardt, Jason

2017-01-01

Knowledge of salmonid life history types at the watershed scale is increasingly recognized as a cornerstone for effective management. In this study, we used radiotelemetry to characterize the life history movements of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri in the upper Yellowstone River, an extensive tributary that composes nearly half of the drainage area of Yellowstone Lake. In Yellowstone Lake, Yellowstone Cutthroat Trout have precipitously declined over the past 2 decades primarily due to predation from introduced Lake Trout Salvelinus namaycush. Radio tags were implanted in 152 Yellowstone Cutthroat Trout, and their movements monitored over 3 years. Ninety-six percent of tagged trout exhibited a lacustrine–adfluvial life history, migrating upstream a mean distance of 42.6 km to spawn, spending an average of 24 d in the Yellowstone River before returning to Yellowstone Lake. Once in the lake, complex postspawning movements were observed. Only 4% of radio-tagged trout exhibited a fluvial or fluvial–adfluvial life history. Low prevalence of fluvial and fluvial–adfluvial life histories was unexpected given the large size of the upper river drainage. Study results improve understanding of life history diversity in potamodromous salmonids inhabiting relatively undisturbed watersheds and provide a baseline for monitoring Yellowstone Cutthroat Trout response to management actions in Yellowstone Lake.

Dielectric-based subwavelength metallic meanders for wide-angle band absorbers.

PubMed

Shen, Su; Qiao, Wen; Ye, Yan; Zhou, Yun; Chen, Linsen

2015-01-26

We propose nano-meanders that can achieve wide-angle band absorption in visible regime. The nano-meander consists of a subwavelength dielectric grating covered by continuous ultra-thin Aluminum film (less than one tenth of the incident wavelength). The excited photonic resonant modes, such as cavity mode, surface plasmonic mode and Rayleigh-Wood anomaly, are discussed in detail. Nearly total resonant absorption due to funneling mechanism in the air nano-groove is almost invariant with large incident angle in transverse magnetic polarization. From both the structural geometry and the nanofabrication point of view, the light absorber has a very simple geometrical structure and it is easy to be integrated into complex photonic devices. The highly efficient angle-robust light absorber can be potential candidate for a range of passive and active photonic applications, including solar-energy harvesting as well as producing artificial colors on a large scale substrate.

Alterations of channel parameters in response to river regulation works since 1840 on the Lower Tisza River (Hungary)

NASA Astrophysics Data System (ADS)

Kiss, Tímea; Fiala, Károly; Sipos, György

2008-06-01

In the last few years an increase in the frequency and magnitude of floods was detected on the Tisza River, endangering large areas of Hungary. The causes of these record floods were complex, including both natural and human induced factors. This paper focuses on river management works and their effect on planimetric and cross-sectional parameters, with special attention to the flood conductivity changes to the river channel. During 19th century river regulation works, half of the total length of the Tisza River was altered by cut-offs, while in the 20th century mostly revetments and groynes were constructed. Subsequently, horizontal and vertical channel parameters have changed considerably due to semi-natural bed processes. In order to reveal changes, hydrological map series (1842, 1890, 1929, 1957, 1976 and 1999) and cross-sectional surveys from the same dates were analysed. Prior to the intensive human interventions (before 1890s) the river's course was highly sinuous with some very sharp bends. Due to cut-offs both the length and sinuosity of the Tisza River decreased by 35%, while the lengths of straight sections and the river's slope doubled. As a consequence the river incised by up to 3.8 m until the 1929 survey, resulting better flood conductivity, which improved flood safety. In the 1920s river management favoured bank stabilisation in order to stop the lateral migration of the channel. Despite these measures, meander development has continued, however, in a distorted manner. This is reflected by the opposing processes of lengthening centre-line on the one hand and gradually decreasing radius of curvature on the other. These processes can be explained by the continuous development of natural point-bars on the convex bank, and the lack of lateral retreat on the concave stabilised bank. The width of the river decreased by 17-45%, while its mean and maximum depth increased by 5-48%. The area of cross-sections influenced by revetments decreased by 6

Channel migration of the White River in the eastern Uinta Basin, Utah and Colorado

USGS Publications Warehouse

Jurado, Antonio; Fields, Fred K.

1978-01-01

The White River is the largest stream in the southeastern part of the Uinta Basin in Utah and Colorado. This map shows the changes that have occurred in the location of the main channel of the river from 1936 to 1974. The map indicated that certain reaches of the river are subject to different rates of channel migration. Also shown is the boundary of the flood plain, which is mapped at the point of abrupt break in slope. This map documents the position of the river channel prior to any withdrawals of water or alteration of the flow characteristics of the white river that may occur in order to meet water requirements principally associated with the proposed oil-shale industry or other development in the area.The channel locations were determined from aerial photographs taken at four different time periods for the following Federal agencies: In 1936, U.S. Soil Conservation Services; 1953, U.S. Corps of Engineers; 1965, U.S. Geological Survey; and in 1974, U.S. Bureau of Land Management. The 1936 delineation, which is actually based upon photographs that were taken in 1936 and 1937, was made by projection of the original photographs on a base map that was prepared from 1:24,000 scale topographic maps. The 1953, 1965, and 1974 delineations were produced from stereographic models. The 1965 delineation was compiled from photographs that were taken during 1962-65. The delineation is labeled as 1965 for simplicity, however, because the photographs for 1965 cover about 60 percent of the study read of the river, and because no changed were discernable in those areas of repetitive photographic coverage.

Hydrodynamic controls on the long-term construction of large river floodplains and alluvial ridges

NASA Astrophysics Data System (ADS)

Nicholas, Andrew; Aalto, Rolf; Sambrook Smith, Gregory; Schwendel, Arved

2017-04-01

Floodplain construction involves the interplay between channel belt sedimentation and avulsion, overbank deposition of fines, and sediment reworking by channel migration. Each of these processes is controlled, in part, by within-channel and/or overbank hydraulics. However, while spatially-distributed hydrodynamic models are used routinely to simulate floodplain inundation and overbank sedimentation during individual floods, most existing models of long-term floodplain construction and alluvial architecture do not account for flood hydraulics explicitly. Instead, floodplain sedimentation is typically modelled as an exponential function of distance from the river, and avulsion thresholds are defined using topographic indices that quantify alluvial ridge morphology (e.g., lateral:downstream slope ratios or metrics of channel belt super-elevation). Herein, we apply a hydraulically driven model of floodplain evolution, in order to quantify the controls on alluvial ridge construction and avulsion likelihood in large lowland rivers. We combine a simple model of meander migration and cutoff with a 2D grid-based model of flood hydrodynamics and overbank sedimentation. The latter involves a finite volume solution of the shallow water equations and an advection-diffusion model for suspended sediment transport. The model is used to carry out a series of numerical experiments to investigate floodplain construction for a range of flood regimes and sediment supply scenarios, and results are compared to field data from the Rio Beni system, northern Bolivia. Model results, supported by field data, illustrate that floodplain sedimentation is characterised by a high degree of intermittency that is driven by autogenic mechanisms (i.e. even in the absence of temporal variations in flood magnitude and sediment supply). Intermittency in overbank deposits occurs over a range of temporal and spatial scales, and is associated with the interaction between channel migration dynamics and

Are Streams in the Southwestern Ozarks Underfit? Applying Dury's model to the Illinois River Watershed in Arkansas.

NASA Astrophysics Data System (ADS)

Shepherd, S. L.; Davis, R. K.; Dixon, J. C.; Cothren, J. D.

2008-12-01

George H. Dury (1964) proposed eight theoretical combinations of stream pattern and valley pattern that represent underfit streams; claiming underfit is a climate induced condition caused by a significant decrease in channel forming discharge. One combination was defined by the Osage River in the northeastern Ozark Plateaus of Missouri. Osage underfit streams fail to meander within a meandering valley. The mean channel meander wavelength and channel width of the stream is much less than the valley resulting in valley-stream ratios of up to 40:1 in contrast to his expected values of approximately 11:1. Dury's model is generally applied to the entire Ozarks including the Illinois River watershed without field data support. The Illinois River is located on the western flank of the Ozark Plateaus physiographic region on the Springfield Plateau which has different lithology than the Salem Plateau where the Osage River is located. To test the assumption that streams in the Illinois River watershed are underfit a combination of field, map, and GIS data were collected. Geomorphic surveys of ten reaches along eight first order streams were completed. The average stream widths of the ten reaches were compared to valley widths measured from USGS 1:24000 Quadrangle maps. The valley to stream ratios ranged from 1 to 15. Forested watersheds exhibited the highest width ratios, ranging from 12 to 15, while ratios in urban and agricultural watersheds were less than 2. This finding is consistent with observed changes in stream morphology caused by anthropogenic influences. To extrapolate to the larger watershed thirteen valley and stream widths along the Illinois River and two higher order tributaries, Osage Creek and Clear Creek, were measured from USGS maps. These ratios ranged from 2.8 to 5.7. Additionally, stream and valley wavelengths are being analyzed in a GIS using the USGS medium resolution hydrology data set and a LiDAR derived 8 m DEM for the watershed. These data suggest

Survival of migrating Atlantic salmon smolts through the Penobscot River, Maine: A pre-restoration assessment

USGS Publications Warehouse

Zydlewski, Joseph D.; Kinnison, Michael T.; Holbrook, Christopher M.

2011-01-01

Survival, distribution, and behavior of hatchery (n = 493) and naturally reared (n = 133) smolts of Atlantic salmon Salmo salar migrating through the Penobscot River and estuary in Maine were evaluated with acoustic telemetry in 2005 and 2006. Survival and use of a secondary migration path (the Stillwater Branch) were estimated with a multistate mark–recapture model. Higher rates of mortality per kilometer (range = 0.01–0.22) were observed near release sites and within reaches that contained three particular dams: Howland, West Enfield, and Milford dams. Estimated total survival of tagged hatchery smolts through entire individual reaches containing those dams ranged from 0.52 ( 0.18) to 0.94 ( 0.09), whereas survival through most of the reaches without dams exceeded 0.95. Of those smolts that survived to the Penobscot River–Stillwater Branch split at Marsh Island, most (≥74%) remained in the main stem around Marsh Island, where they experienced lower survival than fish that used the Stillwater Branch. Movement rates of hatchery-reared smolts were significantly lower through reaches containing dams than through reaches that lacked dams. Smolts arriving at dams during the day experienced longer delays than smolts arriving at night. Planned removal of two dams in this system is expected to enhance the passage of smolts through the main-stem corridor. However, the dams currently scheduled for removal (Great Works and Veazie dams) had less influence on smolt survival than some of the dams that will remain. This case study shows that by examining prerestoration migration dynamics throughout entire river systems rather than just in the vicinity of particular dams, tracking studies can help prioritize restoration efforts or predict the costs and benefits of future hydrosystem changes.

Simulation Comparisons of Three Different Meander Line Dipoles

DTIC Science & Technology

2015-01-01

Paez C I. Design formulas for a meandered dipole. IEEE Xplore Digital Library, 2014: n. pag. Web. 2 September 2014. 2. Nguyen, VH, Phan, HP, Hoang...MH. Improving radiation characteristics of UHF RFID antennas by zigzag structures. IEEE Xplore Digital Library, 2014: n. pag. Web. 2 September 2014...geometry-based, frequency-independent lumped element model. IEEE Xplore Digital Library, 2014: n. pag. Web. 2 September 2014. 5. Olaode OO, Palmer WD

Dynamic reorganization of river basins.

PubMed

Willett, Sean D; McCoy, Scott W; Perron, J Taylor; Goren, Liran; Chen, Chia-Yu

2014-03-07

River networks evolve as migrating drainage divides reshape river basins and change network topology by capture of river channels. We demonstrate that a characteristic metric of river network geometry gauges the horizontal motion of drainage divides. Assessing this metric throughout a landscape maps the dynamic states of entire river networks, revealing diverse conditions: Drainage divides in the Loess Plateau of China appear stationary; the young topography of Taiwan has migrating divides driving adjustment of major basins; and rivers draining the ancient landscape of the southeastern United States are reorganizing in response to escarpment retreat and coastal advance. The ability to measure the dynamic reorganization of river basins presents opportunities to examine landscape-scale interactions among tectonics, erosion, and ecology.

Channel-pattern adjustments and geomorphic characteristics of Elkhead Creek, Colorado, 1937-97

USGS Publications Warehouse

Elliott, John G.; Gyetvai, Stevan

1999-01-01

Onsite channel surveys and sediment measurements made in 1997, aerial photographs taken from 1937 through 1993, and streamflowgaging- station record from 1954 to 1996 were used to determine the probable cause of accelerated streambed and streambank erosion in the lower reaches of Elkhead Creek, a perennial, meandering tributary of the Yampa River. Concern about the possible effects of Elkhead Reservoir, constructed in 1974, has been expressed by landowners living downstream. Evidence cited as an indication of reservoirrelated effects include the trapping of bedloadtransported sediment in the reservoir, vertical incision of the streambed, and lateral erosion causing loss of agricultural land. A large deltaic deposit composed of approximately 163 acre-ft of bedload-transported sediment formed in Elkhead Reservoir between 1974 and 1993, the contemporary bankfull stage of Elkhead Creek is several feet below the elevation of a broad terrace that previously was the flood plain, and lateral erosion at meander bends occurs at a higher rate than in previous periods at some locations.Elkhead Creek meander migration rates were used as a measure of lateral instability in the study reaches. Meander migration rates based on changes in channel centerline position were calculated for three periods from five sets of rectified aerial photographs for reaches upstream and downstream from the reservoir. The creek upstream from Elkhead Reservoir was unaffected by impoundment and was used as the control reach. Mean meander migration rates in the downstream study reach were 1.2 ft/yr from 1938 to 1953, 2.5 ft/yr from 1954 to 1970, and 4.8 ft/yr from 1978 to 1993, compared to rates of 0.5 ft/yr, 1.6 ft/yr, and 6.6 ft/yr for the same periods in the upstream study reach. Sediment and channel-geometry measurements and estimated hydraulic conditions at eight cross sections indicate that most of the sediment sizes represented in the streambed are mobile at frequently occurring streamflows

A Geomorphic Analysis of Floodplain Lakes along the Embanked Lower Mississippi River for Managing Hydrologic Connectivity

NASA Astrophysics Data System (ADS)

Hudson, Paul; Boot, Dax; Sounny-Slitinne, M. Anwar; Kristensen, Kristiaan

2015-04-01

area of floodplain lakes within the embanked floodplain is 382 km2, or 5.2% of the embanked floodplain surface area. Considerable variability in embanked floodplain area along the lower Mississippi, however, results in spatial variability in the frequency of specific lake types. Meander cutoff lakes represent the largest proportion of lake area, at 49%, with approximately half of this area comprised of artificial cutoff lakes. The next largest class of lakes are borrow pit lakes (at 16%), which are anthropogenic water bodies created for the process of levee (dike) construction and maintenance, but which represent valuable environmental habitat. Meander cutoff lakes are especially dominant in the upper reaches of the Lower Mississippi and diminish moving downstream, where the area of embanked floodplain also decreases. Interestingly, anthropogenic lakes (borrow pits) become increasingly prevalent further downstream and dominate over natural formed lakes. The location of lake types along the Lower Mississippi does not correspond with recent historic geomorphic and hydrologic activity. The highest frequency of meander cutoff and crevasse lakes are not located within floodplain sections which historically had the highest rates of lateral migration (m/yr) and flooding (duration). Although overbank hydrologic connectivity varies along the river, it does not vary necessarily where it would be most advantageous to the connectivity of specific types of lakes. The research results provide government agencies with a spatial inventory and methodological approach to improve the management of floodplain water bodies for sustaining valuable aquatic habitat, whether by artificially restricting or enhancing hydrologic connectivity. Key words: floodplain lakes, fluvial geomorphology, hydrologic connectivity, anthropogenic impacts, Lower Mississippi River

Geomorphic adjustment to hydrologic modifications along a meandering river: Implications for surface flooding on a floodplain

NASA Astrophysics Data System (ADS)

Edwards, Brandon L.; Keim, Richard F.; Johnson, Erin L.; Hupp, Cliff R.; Marre, Saraline; King, Sammy L.

2016-09-01

Responses of large regulated rivers to contemporary changes in base level are not well understood. We used field measurements and historical analysis of air photos and topographic maps to identify geomorphic trends of the lower White River, Arkansas, USA, in the 70 years following base-level lowering at its confluence with the Mississippi River and concurrent with flood control by dams. Incision was identified below a knickpoint area upstream of St. Charles, AR, and increases over the lowermost 90 km of the study site to 2 m near the confluence with the Mississippi River. Mean bankfull width increased by 30 m (21%) from 1930 to 2010. Bank widening appears to be the result of flow regulation above the incision knickpoint and concomitant with incision below the knickpoint. Hydraulic modeling indicated that geomorphic adjustments likely reduced flooding by 58% during frequent floods in the incised, lowermost floodplain affected by backwater flooding from the Mississippi River and by 22% above the knickpoint area. Dominance of backwater flooding in the incised reach indicates that incision is more important than flood control on the lower White River in altering flooding and also suggests that the Mississippi River may be the dominant control in shaping the lower floodplain. Overall, results highlight the complex geomorphic adjustment in large river-floodplain systems in response to anthropogenic modifications and their implications, including reduced river-floodplain connectivity.

Influences of body size and environmental factors on autumn downstream migration of bull trout in the Boise River, Idaho

USGS Publications Warehouse

Monnot, L.; Dunham, J.B.; Hoem, T.; Koetsier, P.

2008-01-01

Many fishes migrate extensively through stream networks, yet patterns are commonly described only in terms of the origin and destination of migration (e.g., between natal and feeding habitats). To better understand patterns of migration in bull trout,Salvelinus confluentus we studied the influences of body size (total length [TL]) and environmental factors (stream temperature and discharge) on migrations in the Boise River basin, Idaho. During the autumns of 2001-2003, we tracked the downstream migrations of 174 radio-tagged bull trout ranging in size from 21 to 73 cm TL. The results indicated that large bull trout (>30 cm) were more likely than small fish to migrate rapidly downstream after spawning in headwater streams in early autumn. Large bull trout also had a higher probability of arriving at the current terminus of migration in the system, Arrowrock Reservoir. The rate of migration by small bull trout was more variable and individuals were less likely to move into Arrowrock Reservoir. The rate of downstream migration by all fish was slower when stream discharge was greater. Temperature was not associated with the rate of migration. These findings indicate that fish size and environmentally related changes in behavior have important influences on patterns of migration. In a broader context, these results and other recent work suggest, at least in some cases, that commonly used classifications of migratory behavior may not accurately reflect the full range of behaviors and variability among individuals (or life stages) and environmental conditions. ?? Copyright by the American Fisheries Society 2008.

River sinuosity changes as indicators of the possible neotectonic activity - a case study on the Danube River between Paks (Hungary) and Beograd (Serbia)

NASA Astrophysics Data System (ADS)

Petrovszki, Judit

2010-05-01

The meandering, pre-regulation river planforms of the Danube River, between Paks (Hungary) and Beograd (Serbia) was digitized from the map sheets of the Second Military Survey of the Habsburg Empire (Timár et al., 2006). These maps were surveyed before or simultaneously with the river control works, so it is possible to follow the natural riverbeds, the natural changing of the meandering structure. The sinuosity values were calculated with different window sizes, and displayed in a spectrum-like diagram (sinuosity spectra; after van Balen et al., 2008). The channel sinuosity of this river is analyzed in order to draw conclusions on the neotectonic activity of the western part of the Great Hungarian Plain. Several points of sinuosity change were identified. To prove that these are of neotectonic origin, a neotectonic map and seismic sections crossing the study area, were also analyzed. Significant sinuosity changes (low to high or high to low), spatially correlated to linear features identified in seismic survey sections or in tectonic maps (Horváth et al., 2006), indicate their neotectonic activity (Ouchi, 1985; Timár, 2003; Zámolyi et al., 2010). Upstream of the Hungarian-Serbian border, the Duna (Danube) has anabranching planform, the Baracskai-Duna is the main anabranch. There is a fault on the neotectonic map, crossing both rivers, and cause the decreasing of the sinuosity. The vertical activity of the structural line, which is more or less parallel to the international border, is verified by the sinuosity change. The direction of the change (from high to low sinuosity values) correlates with the normal fault character, shown on the map. Another significant sinuosity change occurs downstream of the Drava River confluence. The explanation of this change can be of two kinds. First, there is a known tectonic feature along the Drava River, with dextral faulting. The sinuosity increase could indicate a small active vertical component of this structural line

Assessing the Importance of Cross-Stream Transport in Bedload Flux Estimates from Migrating Dunes: Colorado River, Grand Canyon National Park

NASA Astrophysics Data System (ADS)

Leary, K. P.; Buscombe, D.; Schmeeckle, M.; Kaplinski, M. A.

2017-12-01

Bedforms are ubiquitous in sand-bedded rivers, and understanding their morphodynamics is key to quantifying bedload transport. As such, mechanistic understanding of the spatiotemporal details of sand transport through and over bedforms is paramount to quantifying total sediment flux in sand-bedded river systems. However, due to the complexity of bedform field geometries and migration in natural settings, our ability to relate migration to bedload flux, and to quantify the relative role of tractive and suspended processes in their dynamics, is incomplete. Recent flume and numerical investigations indicate the potential importance of cross-stream transport, a process previously regarded as secondary and diffusive, to the three-dimensionality of bedforms and spatially variable translation and deformation rates. This research seeks to understand and quantify the importance of cross-stream transport in bedform three-dimensionality in a field setting. This work utilizes a high-resolution (0.25 m grid) data set of bedforms migrating in the channel of the Colorado River in Grand Canyon National Park. This data set comprises multi-beam sonar surveys collected at 3 different flow discharges ( 283, 566, and 1076 m3/s) along a reach of the Colorado River just upstream of the Diamond Creek USGS gage. Data were collected every 6 minutes almost continuously for 12 hours. Using bed elevation profiles (BEPs), we extract detailed bedform geometrical data (i.e. bedform height, wavelength) and spatial sediment flux data over a suite of bedforms at each flow. Coupling this spatially extensive data with a generalized Exner equation, we conduct mass balance calculations that evaluate the possibility, and potential importance, of cross-stream transport in the spatial variability of translation and deformation rates. Preliminary results suggest that intra-dune cross-stream transport can partially account for changes in the planform shape of dunes and may play an important role in spatially

A field reciprocal transplant experiment reveals asymmetric costs of migration between lake and river ecotypes of three-spined sticklebacks (Gasterosteus aculeatus).

PubMed

Kaufmann, J; Lenz, T L; Kalbe, M; Milinski, M; Eizaguirre, C

2017-05-01

Theory of local adaptation predicts that nonadapted migrants will suffer increased costs compared to local residents. Ultimately this process can result in the reduction of gene flow and culminate in speciation. Here, we experimentally investigated the relative fitness of migrants in foreign habitats, focusing on diverging lake and river ecotypes of three-spined sticklebacks. A reciprocal transplant experiment performed in the field revealed asymmetric costs of migration: whereas mortality of river fish was increased under lake conditions, lake migrants suffered from reduced growth relative to river residents. Selection against migrants thus involved different traits in each habitat but generally contributed to bidirectional reduction in gene flow. Focusing particularly on the parasitic environments, migrant fish differed from resident fish in the parasite community they harboured. This pattern correlated with both cellular phenotypes of innate immunity as well as with allelic variation at the genes of the major histocompatibility complex. In addition to showing the costs of migration in three-spined sticklebacks, this study highlights the role of asymmetric selection particularly from parasitism in genotype sorting and in the emergence of local adaptation. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Seasonal Movement and Distribution of Fluvial Adult Bull Trout in Selected Watersheds in the Mid-Columbia River and Snake River Basins

PubMed Central

Starcevich, Steven J.; Howell, Philip J.; Jacobs, Steven E.; Sankovich, Paul M.

2012-01-01

From 1997 to 2004, we used radio telemetry to investigate movement and distribution patterns of 206 adult fluvial bull trout (mean, 449 mm FL) from watersheds representing a wide range of habitat conditions in northeastern Oregon and southwestern Washington, a region for which there was little previous information about this species. Migrations between spawning and wintering locations were longest for fish from the Imnaha River (median, 89 km) and three Grande Ronde River tributaries, the Wenaha (56 km) and Lostine (41 km) rivers and Lookingglass Creek (47 km). Shorter migrations were observed in the John Day (8 km), Walla Walla (20 km) and Umatilla river (22 km) systems, where relatively extensive human alterations of the riverscape have been reported. From November through May, fish displayed station-keeping behavior within a narrow range (basin medians, 0.5–6.2 km). Prespawning migrations began after snowmelt-driven peak discharge and coincided with declining flows. Most postspawning migrations began by late September. Migration rates of individuals ranged from 0.1 to 10.7 km/day. Adults migrated to spawning grounds in consecutive years and displayed strong fidelity to previous spawning areas and winter locations. In the Grande Ronde River basin, most fish displayed an unusual fluvial pattern: After exiting the spawning tributary and entering a main stem river, individuals moved upstream to wintering habitat, often a substantial distance (maximum, 49 km). Our work provides additional evidence of a strong migratory capacity in fluvial bull trout, but the short migrations we observed suggest adult fluvial migration may be restricted in basins with substantial anthropogenic habitat alteration. More research into bull trout ecology in large river habitats is needed to improve our understanding of how adults establish migration patterns, what factors influence adult spatial distribution in winter, and how managers can protect and enhance fluvial populations. PMID

Synthesis of juvenile lamprey migration and passage research and monitoring at Columbia and Snake River Dams

USGS Publications Warehouse

Mesa, Matthew G.; Weiland, Lisa K.; Christiansen, Helena E.

2016-01-01

We compiled and summarized previous sources of data and research results related to the presence, numbers, and migration timing characteristics of juvenile (eyed macropthalmia) and larval (ammocoetes) Pacific lamprey Entosphenus tridentatus, in the Columbia River basin (CRB). Included were data from various screw trap collections, data from historic fyke net studies, catch records of lampreys at JBS facilities, turbine cooling water strainer collections, and information on the occurrence of lampreys in the diets of avian and piscine predators. We identified key data gaps and uncertainties that should be addressed in a juvenile lamprey passage research program. The goal of this work was to summarize information from disparate sources so that managers can use it to prioritize and guide future research and monitoring efforts related to the downstream migration of juvenile Pacific lamprey within the CRB. A common finding in all datasets was the high level of variation observed for CRB lamprey in numbers present, timing and spatial distribution. This will make developing monitoring programs to accurately characterize lamprey migrations and passage more challenging. Primary data gaps centered around our uncertainty on the numbers of juvenile and larval present in the system which affects the ability to assign risk to passage conditions and prioritize management actions. Recommendations include developing standardized monitoring methods, such as at juvenile bypass systems (JBS’s), to better document numbers and timing of lamprey migrations at dams, and use biotelemetry tracking techniques to estimate survival potentials for different migration histories.

The Lowland Rivers of The Netherlands - Geodiversity and Cultural Heritage on 19th and early 20th century Landscape Paintings

NASA Astrophysics Data System (ADS)

Jungerius, Pieter Dirk; van den Ancker, Hanneke; Moes, Constance

2015-04-01

One of the major Dutch landscapes is formed by lowland rivers. They divide the country in a southern and a northern part, both physically and culturally. We screened the freely available database of 19th and early 20th century paintings of Simonis & Buunk, www.simonis-buunk.com, looking for lowland river landscapes depicting geodiversity and cultural heritage relationships (See References for other landscapes). Emperor Napoleon declared The Netherlands as naturally belonging to his empire as its lands originated from muds originating in France and transported there by the big rivers. A description that may have given rise to the idea of the Netherlands as a delta, but from a geomorphological perspective The Netherlands consists of series of river plains of terrestrial origin, of which the north-western part are subsiding and invaded by the sea. Now, the rivers Meuse and Rhine (including its branches Waal and IJssel) meander through ever larger river plains before reaching the North Sea. They end in estuaries, something one would not expect of rivers with catchments discharging a large part of Western Europe. Apart from the geological subsidence, the estuaries might be due to human interference, the exploitation of peat and building of dikes since the 11th century, heavy storms and the strong tidal currents. Archaeological finds show Vikings and Romans already used the river Rhine system for trading and transporting goods. During the Roman Empire the Rhine was part of The Limes, the northern defence line of the empire. Romans already influenced the distribution of water over the different river branches. Since the middle of the 19th century groins and canalization drastically changed the character of the rivers. The 19th and early 20th century landscape paintings illustrate this change as well as changes in land use. Examples of geodiversity and cultural heritage relationships shown: - meanders and irregular banks disappear as river management increases, i.a. bends

A meeting of the waters: interdisciplinary challenges and opportunities in tidal rivers

USGS Publications Warehouse

Ensign, Scott H.; Noe, Gregory B.; Hupp, Cliff R.; Fagherazzi, Sergio

2012-01-01

At the interface of estuarine tides and freshwater rivers lie wetland and aquatic ecosystems, which experience dramatic effects of sea level rise. There, nontidal channels and riparian floodplains are transforming into tidal ecosystems, and tidal freshwater ecosystems are receiving increasing salinity. These river-floodplain systems have both fluvial characteristics, including meandering channels and expansive floodplain forests, and estuarine characteristics, including tides and intertidal wetlands [see Barendregt et al., 2009; Conner et al., 2007, and references therein]. Because tidal rivers lie at the disciplinary divide between fluvial and estuarine science, a knowledge gap has developed in scientists' understanding of the geomorphic and biogeochemical response of these environments to sea level rise, climate change, and anthropogenically driven variations in watershed exports.

Directivity analysis of meander-line-coil EMATs with a wholly analytical method.

PubMed

Xie, Yuedong; Liu, Zenghua; Yin, Liyuan; Wu, Jiande; Deng, Peng; Yin, Wuliang

2017-01-01

This paper presents the simulation and experimental study of the radiation pattern of a meander-line-coil EMAT. A wholly analytical method, which involves the coupling of two models: an analytical EM model and an analytical UT model, has been developed to build EMAT models and analyse the Rayleigh waves' beam directivity. For a specific sensor configuration, Lorentz forces are calculated using the EM analytical method, which is adapted from the classic Deeds and Dodd solution. The calculated Lorentz force density are imported to an analytical ultrasonic model as driven point sources, which produce the Rayleigh waves within a layered medium. The effect of the length of the meander-line-coil on the Rayleigh waves' beam directivity is analysed quantitatively and verified experimentally. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecular Detection of Campylobacter spp. and Fecal Indicator Bacteria during the Northern Migration of Sandhill Cranes (Grus canadensis) at the Central Platte River

PubMed Central

Ryu, Hodon; Vogel, Jason; Santo Domingo, Jorge; Ashbolt, Nicholas J.

2013-01-01

The risk to human health of the annual sandhill crane (Grus canadensis) migration through Nebraska, which is thought to be a major source of fecal pollution of the central Platte River, is unknown. To better understand potential risks, the presence of Campylobacter species and three fecal indicator bacterial groups (Enterococcus spp., Escherichia coli, and Bacteroidetes) was assayed by PCR from crane excreta and water samples collected during their stopover at the Platte River, Nebraska, in 2010. Genus-specific PCR assays and sequence analyses identified Campylobacter jejuni as the predominant Campylobacter species in sandhill crane excreta. Campylobacter spp. were detected in 48% of crane excreta, 24% of water samples, and 11% of sediment samples. The estimated densities of Enterococcus spp. were highest in excreta samples (mean, 4.6 × 108 cell equivalents [CE]/g), while water samples contained higher levels of Bacteroidetes (mean, 5.1 × 105 CE/100 ml). Enterococcus spp., E. coli, and Campylobacter spp. were significantly increased in river water and sediments during the crane migration period, with Enterococcus sp. densities (∼3.3 × 105 CE/g) 2 to 4 orders of magnitude higher than those of Bacteroidetes (4.9 × 103 CE/g), E. coli (2.2 × 103 CE/g), and Campylobacter spp. (37 CE/g). Sequencing data for the 16S rRNA gene and Campylobacter species-specific PCR assays indicated that C. jejuni was the major Campylobacter species present in water, sediments, and crane excreta. Overall, migration appeared to result in a significant, but temporary, change in water quality in spring, when there may be a C. jejuni health hazard associated with water and crops visited by the migrating birds. PMID:23584775

"Investigations of salmon and steelhead trout downstream migrations in Caspar Creek and Little River, Mendocino County, March-July, 1993"

Treesearch

Albert Rodriguez; Weldon Jones

1993-01-01

Abstract - This annual study has been conducted, since 1987, on two coastal streams, in order to observe the different trend patterns of juvenile out migrations for coho salmon and steelhead-trout, figure 1. Analysis of the 1993 trapping season indicates, at Little River, a decrease of steelhead-trout yearlings but an increase in coho ""y+"". Coho...

Jet meandering by a foil pitching in quiescent fluid

NASA Astrophysics Data System (ADS)

Shinde, Sachin Y.; Arakeri, Jaywant H.

2013-04-01

The flow produced by a rigid symmetric NACA0015 airfoil purely pitching at a fixed location in quiescent fluid (the limiting case of infinite Strouhal number) is studied using visualizations and particle image velocimetry. A weak jet is generated whose inclination changes continually with time. This meandering is observed to be random and independent of the initial conditions, over a wide range of pitching parameters.

Tracking Mallards (Anas platyrhynchos) with GPS Satellite Transmitters Along Their Migration Route Through Northeast Asia.

PubMed

Shin, Jeong-Hwa; Lee, Ki-Sup; Kim, Seol-Hee; Hwang, Jong-Kyung; Woo, Chanjin; Kim, Jiyeon; Kim, Jung-Hyun; Suh, Jae-Hwa; Jeong, Jipseol; Wang, Seung-Jun; Chung, Hyen-Mi; Yu, Seung-do; Choi, Kyung-Hee; Mo, In-Pil

2016-05-01

In this study, Global Positioning System satellite transmitters were attached to three mallards (Anas platyrhynchos) wintering in South Korea to track their migration routes, stopover sites, breeding sites, and migration patterns. We successfully tracked only one mallard (no. 108917) from November 15, 2011, to November 29, 2013, and determined separate migration routes in two cases of spring migration and one case of fall migration. The mallard repeatedly migrated to the same final destination, even though the travel path varied. We identified six stopover sites: Hunhe River, Liaohe River, Yinma River, Yalu River, Songjeon Bay, and Dahuofang Reservoir in China and South Korea. The wintering sites of two migration cases were discovered to be identical (Gokgyo River in Asan, South Korea). The terminal sites, which were presumed to be breeding grounds, were the same in both cases (Hinggan League in Inner Mongolia Autonomous Region, China). On the basis of the migration routes identified in this study, we suggest that future efforts to control highly pathogenic avian influenza (HPAI) should not only include avian influenza surveillance but also implement flyway-based strategies, with regard to all countries affected by potential HPAI outbreaks.

Linkages between life history type and migration pathways in freshwater and marine environments for Chinook salmon, Oncorhynchus tshawytscha

NASA Astrophysics Data System (ADS)

Sharma, Rishi; Quinn, Thomas P.

2012-05-01

Chinook salmon, Oncorhynchus tshawytscha, are commonly categorized as ocean-type (migrating to the ocean in their first year of life) or stream-type (migrating after a full year in freshwater). These two forms have been hypothesized to display different ocean migration pathways; the former are hypothesized to migrate primarily on the continental shelf whereas the latter are hypothesized to migrate off the shelf to the open ocean. These differences in migration patterns have important implications for management, as fishing mortality rates are strongly influenced by ocean migration. Ocean-type Chinook salmon predominate in coastal rivers in the southern part of the species' range, whereas stream-type predominate in the interior and northerly rivers. This latitudinal gradient has confounded previous efforts to test the hypothesis regarding ocean migration pathways. To address this problem, we used a pair-wise design based on coded wire tagging data to compare the marine distributions of stream- and ocean-type Chinook salmon from a suite of rivers producing both forms. Both forms of Chinook salmon from the lower Columbia River, Oregon coast, lower Fraser River, and northern British Columbia rivers followed similar migration paths, contradicting the hypothesis. In contrast, recoveries of tagged Chinook salmon from the upper Columbia River, Snake River, and the upper Fraser River revealed migration patterns consistent with the hypothesis. These findings have important implications for our understanding of these life history types, and also for the conservation and management of declining, threatened, or endangered stream-type Chinook salmon populations in the US and Canada.

Spawning migration of lacustrine-adfluvial bull trout in a natural area

USGS Publications Warehouse

Brenkman, Samuel J.; Larson, Gary L.; Gresswell, Robert E.

2001-01-01

We investigated the spawning migration of lacustrine-adfluvial bull trout Salvelinus confluentus in the North Fork Skokomish River in Olympic National Park (Washington State) during 1996. Day-snorkeling and electrofishing were conducted to determine timing and duration of the migration and the distribution and abundance of bull trout. The primary spawning migration began in early October and was waning by December. Bull trout migrated 6 km or less up the river from Lake Cushman. Increased river discharge and decreased water temperature appeared to be the primary environmental variables corresponding to the initiation of the migration. Mean length of migratory bull trout increased from June to December. Comparisons with other lacustrine-adfluvial bull trout populations in Oregon, Montana, Idaho, and British Columbia suggested that these populations exhibit specific migratory strategies related to local environmental conditions.

Measuring the Timing, Magnitude, and Rate of Rock uplift of Sierra Madre Mountains with CRN Analysis of Relict Landscapes and Strath Terraces

NASA Astrophysics Data System (ADS)

Schoettle, E.; Burbank, D. W.; Bookhagen, B.

2014-12-01

California's Sierra Madre Mountains lie at the junction of the Coast and Transverse Ranges, where they form an arcuate range crest with peak elevations of nearly 1,800 m. Near the range crest, a gently sloping paleovalley in the Southern Sierra Madre is being consumed by the headward migration of a prominent knickpoint, with an ~250-m-high headwall abutting below the gently sloped paleovalley. This paleovalley at 1400 m elevation and other low-relief, high-elevation remnants in the Sierra Madres at elevations from 800-1400 m show that the range is young enough to have regions not yet in equilibrium with the modern base level and uplift rate. Toward the western end of the Sierra Madre, the Cuyama River cuts a bedrock canyon through the range. The canyon planform describes a meandering river that has now incised ~400 m into the range. The combination of (i) high-altitude, low-relief surfaces in the Sierra Madre including the paleovalley with (ii) a meandering planform that has been incised into bedrock by a transverse river suggests (1) a low-altitude meandering proto-Cuyama river preceded significant rock uplift, and (2) the river's incision records the rock uplift of the range. Using cosmogenic nuclides to measure both the bedrock-lowering rate of the high-elevation paleovalley and the erosion rate of the steep catchment eroding into it, we can place some limits on the timing and magnitude of rock uplift in the range. By dating bedrock straths along the river canyon's walls, we can directly quantify the pace of channel incision. Together these new estimates will yield an improved reconstruction of the timing, magnitude, and rate of rock uplift of the Sierra Madre.

A Modelling Framework to Assess the Effect of Pressures on River Abiotic Habitat Conditions and Biota

PubMed Central

Kail, Jochem; Guse, Björn; Radinger, Johannes; Schröder, Maria; Kiesel, Jens; Kleinhans, Maarten; Schuurman, Filip; Fohrer, Nicola; Hering, Daniel; Wolter, Christian

2015-01-01

River biota are affected by global reach-scale pressures, but most approaches for predicting biota of rivers focus on river reach or segment scale processes and habitats. Moreover, these approaches do not consider long-term morphological changes that affect habitat conditions. In this study, a modelling framework was further developed and tested to assess the effect of pressures at different spatial scales on reach-scale habitat conditions and biota. Ecohydrological and 1D hydrodynamic models were used to predict discharge and water quality at the catchment scale and the resulting water level at the downstream end of a study reach. Long-term reach morphology was modelled using empirical regime equations, meander migration and 2D morphodynamic models. The respective flow and substrate conditions in the study reach were predicted using a 2D hydrodynamic model, and the suitability of these habitats was assessed with novel habitat models. In addition, dispersal models for fish and macroinvertebrates were developed to assess the re-colonization potential and to finally compare habitat suitability and the availability / ability of species to colonize these habitats. Applicability was tested and model performance was assessed by comparing observed and predicted conditions in the lowland Treene River in northern Germany. Technically, it was possible to link the different models, but future applications would benefit from the development of open source software for all modelling steps to enable fully automated model runs. Future research needs concern the physical modelling of long-term morphodynamics, feedback of biota (e.g., macrophytes) on abiotic habitat conditions, species interactions, and empirical data on the hydraulic habitat suitability and dispersal abilities of macroinvertebrates. The modelling framework is flexible and allows for including additional models and investigating different research and management questions, e.g., in climate impact research as well

Meandering Right Pulmonary Vein to the Left Atrium and Inferior Vena Cava

PubMed Central

Tortoriello, Tia A.; Vick, G. Wesley; Chung, Taylor; Bezold, Louis I.; Vincent, Julie A.

2002-01-01

We report a case of a healthy, asymptomatic 6-year-old boy in whom an anomalous right pulmonary vein was noted to drain into both the inferior vena cava and left atrium in association with findings consistent with scimitar syndrome. The anomalous pulmonary vein took a very circuitous route through the lungs before draining into the left atrium, a condition previously termed “meandering pulmonary vein.” To aid in the diagnosis, cardiovascular magnetic resonance imaging and magnetic resonance angiography were used to delineate this complex course and the connection of the anomalous pulmonary vein. To our knowledge, this is the 1st reported case of a meandering pulmonary vein with dual drainage to the inferior vena cava and left atrium in association with other anomalies. (Tex Heart Inst J 2002;29:319–23) PMID:12484618

Summary of Migration and Survival Data from Radio-Tagged Juvenile Coho Salmon in the Trinity River, Northern California, 2008

USGS Publications Warehouse

Beeman, John W.; Hansel, Hal; Juhnke, Steve; Stutzer, Greg

2009-01-01

The survival of hatchery-origin juvenile coho salmon from the Trinity River Hatchery was estimated as they migrated seaward through the Trinity and Klamath Rivers. The purpose of the study was to collect data for comparison to a similar study in the Klamath River and provide data to the Trinity River Restoration Program. A total of 200 fish fitted with radio transmitters were released into the Trinity River near the hatchery (river kilometer 252 from the mouth of the Klamath River) biweekly from March 19 to May 28, 2008. Fish from the earliest release groups took longer to pass the first detection site 10 kilometers downstream of the hatchery than fish from the later release groups, but travel times between subsequent sites were often similar among the release groups. The travel times of individuals through the 239 kilometer study area ranged from 15.5 to 84.6 days with a median of 43.3 days. The data and models did not support differences in survival among release groups, but did support differences among river reaches. The probability of survival in the first 53 kilometers was lower than in the reaches farther downstream, which is similar to trends in juvenile coho salmon in the Klamath River. The lowest estimated survival in this study was in the first 10 kilometers from release in the Trinity River (0.676 SE 0.036) and the highest estimated survival was in the final 20 kilometer reach in the Klamath River (0.987 SE 0.013). Estimated survivals of radio-tagged juvenile coho salmon from release to Klamath River kilometer 33 were 0.639 per 100 kilometers for Trinity River fish and 0.721 per 100 kilometers for Klamath River fish.

Molecular detection of Campylobacter spp. and fecal indicator bacteria during the northern migration of sandhill cranes (Grus canadensis) at the central Platte River.

PubMed

Lu, Jingrang; Ryu, Hodon; Vogel, Jason; Santo Domingo, Jorge; Ashbolt, Nicholas J

2013-06-01

The risk to human health of the annual sandhill crane (Grus canadensis) migration through Nebraska, which is thought to be a major source of fecal pollution of the central Platte River, is unknown. To better understand potential risks, the presence of Campylobacter species and three fecal indicator bacterial groups (Enterococcus spp., Escherichia coli, and Bacteroidetes) was assayed by PCR from crane excreta and water samples collected during their stopover at the Platte River, Nebraska, in 2010. Genus-specific PCR assays and sequence analyses identified Campylobacter jejuni as the predominant Campylobacter species in sandhill crane excreta. Campylobacter spp. were detected in 48% of crane excreta, 24% of water samples, and 11% of sediment samples. The estimated densities of Enterococcus spp. were highest in excreta samples (mean, 4.6 × 10(8) cell equivalents [CE]/g), while water samples contained higher levels of Bacteroidetes (mean, 5.1 × 10(5) CE/100 ml). Enterococcus spp., E. coli, and Campylobacter spp. were significantly increased in river water and sediments during the crane migration period, with Enterococcus sp. densities (~3.3 × 10(5) CE/g) 2 to 4 orders of magnitude higher than those of Bacteroidetes (4.9 × 10(3) CE/g), E. coli (2.2 × 10(3) CE/g), and Campylobacter spp. (37 CE/g). Sequencing data for the 16S rRNA gene and Campylobacter species-specific PCR assays indicated that C. jejuni was the major Campylobacter species present in water, sediments, and crane excreta. Overall, migration appeared to result in a significant, but temporary, change in water quality in spring, when there may be a C. jejuni health hazard associated with water and crops visited by the migrating birds.

Long-term changes in river-floodplain dynamics: implications for salmonid habitat in the Interior Columbia Basin, USA.

PubMed

Tomlinson, Matthew J; Gergel, Sarah E; Beechie, Timothy J; McClure, Michelle M

2011-07-01

Rivers and their associated floodplains are among the world's most highly altered ecosystems, resulting in billions of dollars in restoration expenditures. Successful restoration of these systems requires information at multiple spatial scales (from localized reaches to broader-scale watersheds), as well as information spanning long time frames. Here, we develop a suite of historical landscape indicators of riverine status, primarily from the perspective of salmonid management, using a case study in the Interior Columbia Basin, Washington, USA. We use a combination of historical and modern aerial photography to quantify changes in land cover and reach type, as well as potential fish habitat within channel and off-channel floodplain areas. As of 1949, 55% of the Wenatchee River floodplain had been converted to agriculture. By 2006, 62% had been modified by anthropogenic development, of which 20% was due to urban expansion. The historical percentage of agricultural land in the watershed and the contemporary percentage of urban area surpass thresholds in land cover associated with deleterious impacts on river systems. In addition, the abundance of reach types associated with the highest quality salmonid habitat (island braided and meandering reaches) has declined due to conversion to straight reach types. The area occupied by fish habitats associated with channel migration (slow/stagnant channels and dry channels) has declined approximately 25-30%. Along highly modified rivers, these habitats have also become increasingly fragmented. Caveats related to visual quality and seasonal timing of historical photographs were important considerations in the interpretation of changes witnessed for headwater island braided systems, as well as for floodplain ponds. Development of rigorous, long-term, multi-scale monitoring techniques is necessary to guide the management and restoration of river-floodplain systems for the diversity of ecosystem services they provide.

Changes in Channel Geometry through the Holocene in the Le Sueur River, South-Central Minnesota, USA

NASA Astrophysics Data System (ADS)

Targos, Courtney Ann

Paleochannels preserved on terraces via meander cutoffs during an incisional period record the channel geometry and thus discharge at distinct points in time throughout a river's history. We measured paleochannel geometry on terraces throughout the Le Sueur River in south-central Minnesota, to track how channel geometry has changed over the last 13,400 years. A rapid drop in base level 13,400 yr B.P. triggered knickpoint migration and valley incision that is ongoing today. Since the 1800's, the area has developed rapidly with an increase in agriculture and associated drainage, directly impacting river discharge by increasing water input to the river. Five paleochannels were identified on terraces along the Le Sueur River from 1m-resolution lidar data. Ground Penetrating Radar (GPR) was used to obtain a subsurface image across paleomeanders to estimate the geometry of paleochannels. Paleochannel geometry and estimated discharge were then compared to modern conditions to assess how much change has occurred. Three lines were run across each paleochannel perpendicular to the historic water flow. Each of the 15 lines were processed using the EKKO Project 2 software supplied by Sensors and Software to sharpen the images, making it easier to identify the paleochannel geometry. Paleodischarge was determined using the Law of the Wall and Manning's Equation, using modern slope and roughness conditions. OSL samples were collected from overbank deposits on terraces to determine the time of channel abandonment, and supplemented with terrace ages obtained from a numerical model of valley incision. Paleodischarge coupled with depositional ages provide a history of flow conditions on the Le Sueur River. Results show an increase in channel widths from the time paleochannels were occupied to modern channel dimensions from an average of 20 meters to 35 meters. The change was not constant through time, as all paleochannels analyzed on terraces had similar-sized channels. The best way

Migration depths of juvenile Chinook salmon and steelhead relative to total dissolved gas supersaturation in a Columbia River reservoir

USGS Publications Warehouse

Beeman, J.W.; Maule, A.G.

2006-01-01

The in situ depths of juvenile salmonids Oncorhynchus spp. were studied to determine whether hydrostatic compensation was sufficient to protect them from gas bubble disease (GBD) during exposure to total dissolved gas (TDG) supersaturation from a regional program of spill at dams meant to improve salmonid passage survival. Yearling Chinook salmon O. tshawytscha and juvenile steelhead O. mykiss implanted with pressure-sensing radio transmitters were monitored from boats while they were migrating between the tailrace of Ice Harbor Dam on the Snake River and the forebay of McNary Dam on the Columbia River during 1997-1999. The TDG generally decreased with distance from the tailrace of the dam and was within levels known to cause GBD signs and mortality in laboratory bioassays. Results of repeated-measures analysis of variance indicated that the mean depths of juvenile steelhead were similar throughout the study area, ranging from 2.0 m in the Snake River to 2.3 m near the McNary Dam forebay. The mean depths of yearling Chinook salmon generally increased with distance from Ice Harbor Dam, ranging from 1.5 m in the Snake River to 3.2 m near the forebay. Juvenile steelhead were deeper at night than during the day, and yearling Chinook salmon were deeper during the day than at night. The TDG level was a significant covariate in models of the migration depth and rates of each species, but no effect of fish size was detected. Hydrostatic compensation, along with short exposure times in the area of greatest TDG, reduced the effects of TDG exposure below those generally shown to elicit GBD signs or mortality. Based on these factors, our results indicate that the TDG limits of the regional spill program were safe for these juvenile salmonids.

Impact of different meander sizes on the RF transmit performance and coupling of microstrip line elements at 7 T.

PubMed

Rietsch, Stefan H G; Quick, Harald H; Orzada, Stephan

2015-08-01

In this work, the transmit performance and interelement coupling characteristics of radio frequency (RF) antenna microstrip line elements are examined in simulations and measurements. The initial point of the simulations is a microstrip line element loaded with a phantom. Meander structures are then introduced at the end of the element. The size of the meanders is increased in fixed steps and the magnetic field is optimized. In continuative simulations, the coupling between identical elements is evaluated for different element spacing and loading conditions. Verification of the simulation results is accomplished in measurements of the coupling between two identical elements for four different meander sizes. Image acquisition on a 7 T magnetic resonance imaging (MRI) system provides qualitative and quantitative comparisons to confirm the simulation results. Simulations point out an optimum range of meander sizes concerning coupling in all chosen geometric setups. Coupling measurement results are in good agreement with the simulations. Qualitative and quantitative comparisons of the acquired MRI images substantiate the coupling results. The coupling between coil elements in RF antenna arrays consisting of the investigated element types can be optimized under consideration of the central magnetic field strength or efficiency depending on the desired application.

Man versus Rivers: the lost equilibrium of the Tisza River due to engineering works

NASA Astrophysics Data System (ADS)

Kiss, Timea; Fiala, Károly

2016-04-01

The direct and indirect human impacts alter the catchment and the channel characteristics, which will result in further hydro-morphological alterations of rivers. The modified fluvial environment will create new hydrological hazards for the society, so for the successful and sustainable hazard and risk management it is important to evaluate the equilibrium and sensitivity of rivers. The aim of the paper is to evaluate the hydrological and morphological effects of engineering works along the Tisza River, Hungary. Based on the trends of the different fluvial processes the equilibrium of the river will be evaluated to ground further engineering works. The Tisza River, was one of the first systematically regulated rivers in Europe. In the late 19th century artificial cut-offs were made, shortening the river by ca. 30%. The hydrology and the morphology of the Tisza adapted to this, as the channel became temporarily wider and deeper (by 20-25%). The cut-offs had an effect on the channel for ca. 60-70 years. Simultaneously, artificial levees were built, thus the overbank floodplain aggradation became more intensive (from 0.02-0.07 cm/y to 0.3-0.8 mm/y). The floodplain aggradation became higher by 2-4 times since 1970's, as the vegetation became denser. However, in the 21st c. the floodplain vegetation became so uncontrollably dense, that the pattern and rate of accumulation changed again, and now it is limited just to the banks. So the levee could be considered as continuous disturbing factor, besides, the unmanaged floodplain vegetation appeared as a new disturbing force accelerating the processes. In the 20th century revetments were constructed to stop the lateral migration of the channel. This resulted in channel distortion, as it became sharper and the cross-sectional area decreased by 28%. As revetments were constructed along ca. 51% of the channel, the meandering channel forms became replaced features characteristic in incising rivers, for example point

To See or Not to See: Investigating Detectability of Ganges River Dolphins Using a Combined Visual-Acoustic Survey

PubMed Central

Richman, Nadia I.; Gibbons, James M.; Turvey, Samuel T.; Akamatsu, Tomonari; Ahmed, Benazir; Mahabub, Emile; Smith, Brian D.; Jones, Julia P. G.

2014-01-01

Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring. PMID:24805782

To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.

PubMed

Richman, Nadia I; Gibbons, James M; Turvey, Samuel T; Akamatsu, Tomonari; Ahmed, Benazir; Mahabub, Emile; Smith, Brian D; Jones, Julia P G

2014-01-01

Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring.

Measuring Plume Meander in the Nighttime Stable Boundary Layer with Lidar

NASA Astrophysics Data System (ADS)

Hiscox, A.; Miller, D. R.; Nappo, C. J.

2009-12-01

Complex dynamics of the stable planetary boundary layer (PBL), such as the effects of density currents, intermittent turbulence, surface-layer decoupling, internal gravity waves, cold air pooling, and katabatic flows affect plume transport and diffusion. A better understanding of these effects is needed for nighttime transport model development. The JORNADA (Joint Observational Research on Nocturnal Atmospheric Dispersion of Aerosols) field campaign, conducted in the New Mexico desert during April 2005, sought to address some of these issues The JORNADA data set includes simultaneous micrometeorological measurements of the boundary layer structure, turbulence, and wave activity along with continuous lidar measurement of aerosol plume releases. What makes JORNADA unique is the real-time monitoring of an elevated plume with a lidar. The quantification of plume meander will be presented in this paper. The application of these techniques to the JORNADA data allows for a more complete understanding of the nocturnal boundary layer (NBL). We will present an in-depth analysis of lidar measurements of plume meander and dispersion and their relationship to the complexities of NBL structure.

Ontogenetic behavior and migration of Volga River Russian sturgeon, Acipenser gueldenstaedtii, with a note on adaptive significance of body color

USGS Publications Warehouse

Kynard, B.; Zhuang, P.; Zhang, L.; Zhang, T.; Zhang, Z.

2002-01-01

We conducted laboratory experiments with Volga River Russian sturgeon, Acipenser gueldenstaedtii, to develop a conceptual model of early behavior. We daily observed fish from day-0 (embryos, first life interval after hatching) to day-29 feeding larvae for preference of bright habitat and cover, swimming distance above the bottom, up- and downstream movement, and diel activity. Hatchling embryos initiated a downstream migration, which suggests that predation risk of embryos at spawning sites is high. Migration peaked on days 0-5 and ceased on day 7 (8-day migration). Migrants preferred bright, open habitat and early migrants swam-up far above the bottom (maximum daily median, 140 cm) in a vertical swim tube. Post-migrant embryos did not prefer bright illumination but continued to prefer white substrate, increased use of cover habitat, and swam on the bottom. Larvae initiated feeding on day 10 after 170.6 cumulative temperature degree-days. Larvae did not migrate, weakly preferred bright illumination, preferred white substrate and open habitat, and swam near the bottom (daily median 5-78 cm). The lack of a strong preference by larvae for bright illumination suggests foraging relies more on olfaction than vision for locating prey. A short migration by embryos would disperse wild sturgeon from a spawning area, but larvae did not migrate, so a second later migration by juveniles disperses young sturgeon to the sea (2-step migration). Embryo and larva body color was light tan and tail color was black. The migration, behavior, and light body color of Russian sturgeon embryos was similar to species of Acipenser and Scaphirhynchus in North America and to Acipenser in Asia that migrate after hatching as embryos. The similarity in migration style and body color among species with diverse phylogenies likely reflects convergence for common adaptations across biogeographic regions. ?? 2002 Kluwer Academic Publishers.

Modeling survival of juvenile salmon during downriver migration in the Columbia River on a microcomputer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peloquin, R.A.; McKenzie, D.H.

1994-10-01

A compartmental model has been implemented on a microcomputer as an aid in the analysis of alternative solutions to a problem. The model, entitled Smolt Survival Simulator, simulates the survival of juvenile salmon during their downstream migration and passage of hydroelectric dams in the Columbia River. The model is designed to function in a workshop environment where resource managers and fisheries biologists can study alternative measures that may potentially increase juvenile anadromous fish survival during downriver migration. The potential application of the model has placed several requirements on the implementing software. It must be available for use in workshop settings.more » The software must be easily to use with minimal computer knowledge. Scenarios must be created and executed quickly and efficiently. Results must be immediately available. Software design emphasis vas placed on the user interface because of these requirements. The discussion focuses on methods used in the development of the SSS software user interface. These methods should reduce user stress and alloy thorough and easy parameter modification.« less

Challenges of river basin management: Current status of, and prospects for, the River Danube from a river engineering perspective.

PubMed

Habersack, Helmut; Hein, Thomas; Stanica, Adrian; Liska, Igor; Mair, Raimund; Jäger, Elisabeth; Hauer, Christoph; Bradley, Chris

2016-02-01

In the Danube River Basin multiple pressures affect the river system as a consequence of river engineering works, altering both the river hydrodynamics and morphodynamics. The main objective of this paper is to identify the effects of hydropower development, flood protection and engineering works for navigation on the Danube and to examine specific impacts of these developments on sediment transport and river morphology. Whereas impoundments are characterised by deposition and an excess of sediment with remobilisation of fine sediments during severe floods, the remaining five free flowing sections of the Danube are experiencing river bed erosion of the order of several centimetres per year. Besides the effect of interruption of the sediment continuum, river bed degradation is caused by an increase in the sediment transport capacity following an increase in slope, a reduction of river bed width due to canalisation, prohibition of bank erosion by riprap or regressive erosion following base level lowering by flood protection measures and sediment dredging. As a consequence, the groundwater table is lowered, side-arms are disconnected, instream structures are lost and habitat quality deteriorates affecting the ecological status of valuable floodplains. The lack of sediments, together with cutting off meanders, leads also to erosion of the bed of main arms in the Danube Delta and coastal erosion. This paper details the causes and effects of river engineering measures and hydromorphological changes for the Danube. It highlights the importance of adopting a basin-wide holistic approach to river management and demonstrates that past management in the basin has been characterised by a lack of integration. To-date insufficient attention has been paid to the wide-ranging impacts of river engineering works throughout the basin: from the basin headwaters to the Danube Delta, on the Black Sea coast. This highlights the importance of new initiatives that seek to advance knowledge

Molecular detection of Campylobacter spp. and fecal indicator bacteria during the northern migration of Sandhill Cranes (Grus canadensis) at the Central Platte River

EPA Science Inventory

The annual Sandhill crane (Grus canadensis) migration through Nebraska is thought to be a major source of fecal pollution to the Platte River, but of unknown human health risk. To better understand potential risks, the presence of Campylobacter species and fecal bacteria were exa...

Morphodynamics of the Kulsi River Basin in the northern front of Shillong Plateau: Exhibiting episodic inundation and channel migration

NASA Astrophysics Data System (ADS)

Imsong, Watinaro; Choudhury, Swapnamita; Phukan, Sarat; Duarah, Bhagawat Pran

2018-02-01

The present study is undertaken in the Kulsi River valley, a tributary of the Brahmaputra River that drains through the tectonically active Shillong Plateau in northeast India. Based on the fluvial geomorphic parameters and Landsat satellite images, it has been observed that the Kulsi River migrated 0.7-2 km westward in its middle course in the past 30 years. Geomorphic parameters such as longitudinal profile analysis, stream length gradient index ( SL), ratio of valley floor width to valley height ( Vf), steepness index (ks) indicate that the upstream segment of the Kulsi River is tectonically more active than the downstream segment which is ascribed to the tectonic activities along the Guwahati Fault. ^{14}C ages obtained from the submerged tree trunks of the Chandubi Lake, which is located in the central part of the Kulsi River catchment suggests inundation (high lake levels) during 160 ± 50 AD, 970 ± 50 AD, 1190 ± 80 AD and 1520 ± 30 AD, respectively. These periods broadly coincide with the late Holocene strengthened Indian Summer Monsoon (ISM), Medieval Warm Period (MWP) and the early part of the Little Ice Age (LIA). The debris which clogged the course of the river in the vicinity of the Chandubi Lake is attributed to tectonically induced increase in sediment supply during high magnitude flooding events.

Potential Effects of Hydroelectric Dam Development in the Mekong River Basin on the Migration of Siamese Mud Carp (Henicorhynchus siamensis and H. lobatus) Elucidated by Otolith Microchemistry

PubMed Central

Fukushima, Michio; Jutagate, Tuantong; Grudpan, Chaiwut; Phomikong, Pisit; Nohara, Seiichi

2014-01-01

The migration of Siamese mud carp (Henicorhynchus siamensis and H. lobatus), two of the most economically important fish species in the Mekong River, was studied using an otolith microchemistry technique. Fish and river water samples were collected in seven regions throughout the whole basin in Thailand, Laos and Cambodia over a 4 year study period. There was coherence between the elements in the ambient water and on the surface of the otoliths, with strontium (Sr) and barium (Ba) showing the strongest correlation. The partition coefficients were 0.409–0.496 for Sr and 0.055 for Ba. Otolith Sr-Ba profiles indicated extensive synchronized migrations with similar natal origins among individuals within the same region. H. siamensis movement has been severely suppressed in a tributary system where a series of irrigation dams has blocked their migration. H. lobatus collected both below and above the Khone Falls in the mainstream Mekong exhibited statistically different otolith surface elemental signatures but similar core elemental signatures. This result suggests a population originating from a single natal origin but bypassing the waterfalls through a passable side channel where a major hydroelectric dam is planned. The potential effects of damming in the Mekong River are discussed. PMID:25099147

Evaluation of energy expenditure in adult spring Chinook salmon migrating upstream in the Columbia River Basin: an assessment based on sequential proximate analysis

USGS Publications Warehouse

Mesa, M.G.; Magie, C.D.

2006-01-01

The upstream migration of adult anadromous salmonids in the Columbia River Basin (CRB) has been dramatically altered and fish may be experiencing energetically costly delays at dams. To explore this notion, we estimated the energetic costs of migration and reproduction of Yakima River-bound spring Chinook salmon Oncorhynchus tshawytscha using a sequential analysis of their proximate composition (i.e., percent water, fat, protein, and ash). Tissues (muscle, viscera, and gonad) were sampled from fish near the start of their migration (Bonneville Dam), at a mid point (Roza Dam, 510 km upstream from Bonneville Dam) and from fresh carcasses on the spawning grounds (about 100 km above Roza Dam). At Bonneville Dam, the energy reserves of these fish were remarkably high, primarily due to the high percentage of fat in the muscle (18-20%; energy content over 11 kJ g-1). The median travel time for fish from Bonneville to Roza Dam was 27 d and ranged from 18 to 42 d. Fish lost from 6 to 17% of their energy density in muscle, depending on travel time. On average, fish taking a relatively long time for migration between dams used from 5 to 8% more energy from the muscle than faster fish. From the time they passed Bonneville Dam to death, these fish, depending on gender, used 95-99% of their muscle and 73-86% of their viscera lipid stores. Also, both sexes used about 32% of their muscular and very little of their visceral protein stores. However, we were unable to relate energy use and reproductive success to migration history. Our results suggest a possible influence of the CRB hydroelectric system on adult salmonid energetics.

Transport of Solar Energetic Particles across the Parker field direction due to field line meandering

NASA Astrophysics Data System (ADS)

Laitinen, T. L.; Kopp, A.; Effenberger, F.; Dalla, S.; Marsh, M. S.

2014-12-01

Multi-spacecraft observations of Solar Energetic Particles (SEPs) show that the SEPs can spread large distances across the mean Parker spiral field. The SEPs accelerated during a solar eruption can be observed 360° around the Sun, and the dependence of SEP peak intensity on heliographic longitude at 1 AU has been fitted with Gaussian profiles with σ=30-50° for several events (e.g., Dresing et al 2014; Richardson et al 2014). SEP anisotropy measurements suggest that interplanetary transport is an important factor to the SEP cross-field extent (Dresing et al 2014). However, the currently used diffusive Fokker Planck (FP) description of SEP transport, with realistic diffusion coefficients, has been found insufficient to explain the SEP event cross-field extents. Recently Laitinen et al (2013) emphasised the importance of particle propagation along meandering field lines, which cannot be described as diffusion. They showed that early in an event field line meandering dominates particle cross-field transport and produces events wider than the FP description. They also introduced a new FP model that incorporates both field line meandering and SEP cross-field diffusion using stochastic differential equations and a constant background magnetic field. In this work, we implement the new FP model into Parker field geometry, to study the evolution of an SEP event in the interplanetary space. We compare the new model to the traditional FP approach by using particle and field line diffusion coefficients that are calculated consistently for both models using an assumed radial and spectral description of the turbulence evolution. We find that while the traditional SEP propagation modelling gives typically longitudinal extent with σ=10-20°, the new model results in values σ=30-50°, which is consistent with SEP observations. We conclude that field line meandering must be taken into account when modelling SEP propagation in the interplanetary space.

Counterintuitive migration patterns by Atlantic salmon Salmo salar smolts in a large lake.

PubMed

Honkanen, H M; Rodger, J R; Stephen, A; Adams, K; Freeman, J; Adams, C E

2018-06-21

What little is known about the seaward migration of Salmo salar smolt migration through standing waters indicates that it is both slow and results in high mortality rates, compared with riverine migration. This may be partly because smolts in lakes need to swim more actively and require more complex directional cues than they do in rivers. In this telemetry study of smolt migration through Loch Lomond, S. salar smolts made repeated movements in directions away from the outflowing river, which considerably increased migration time. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Satellite tracking of the migration of Whooper Swans Cygnus cygnus wintering in Japan

USGS Publications Warehouse

Shimada, Tetsuo; Yamaguchi, Noriyuki M.; Hijikata, N.; Hiraoka, Emiko N.; Hupp, Jerry W.; Flint, Paul L.; Tokita, Ken-ichi; Fujita, Go; Uchida, Kiyoshi; Sato, F.; Kurechi, Masayuki; Pearce, John M.; Ramey, Andy M.; Higuchi, Hiroyoshi

2014-01-01

We satellite-tracked Whooper Swans Cygnus cygnus wintering in northern Japan to document their migration routes and timing, and to identify breeding areas. From 47 swans that we marked at Lake Izunuma-Uchinuma, Miyagi Prefecture, northeast Honshu, and at Lake Kussharo, east Hokkaido, we observed 57 spring and 33 autumn migrations from 2009-2012. In spring, swans migrated north along Sakhalin Island from eastern Hokkaido using stopovers in Sakhalin, at the mouth of the Amur River and in northern coastal areas of the Sea of Okhotsk. They ultimately reached molting/breedmg areas along the Indigirka River and the lower Kolyma River in northern Russia. In autumn, the swans basically reversed the spring migration routes. We identified northern Honshu, eastern Hokkaido, coastal areas in Sakhalin, the lower Amur River and northern coastal areas of the Sea of Okhotsk as the most frequent stopover sites, and the middle reaches of the Indigirka and the lower Kolyma River as presumed breeding sites. Our results are helpful in understanding the distribution of the breeding and stopover sites of Whooper Swans wintering in Japan and in identifying their major migration habitats. Our findings contribute to understanding the potential transmission process of avian influenza viruses potentially carried by swans, and provide information necessary to conserve Whooper Swans in East Asia.

Effects of an extreme flood on river morphology (case study: Karoon River, Iran)

NASA Astrophysics Data System (ADS)

Yousefi, Saleh; Mirzaee, Somayeh; Keesstra, Saskia; Surian, Nicola; Pourghasemi, Hamid Reza; Zakizadeh, Hamid Reza; Tabibian, Sahar

2018-03-01

An extreme flood occurred on 14 April 2016 in the Karoon River, Iran. The occurred flood discharge was the highest discharge recorded over the last 60 years in the Karoon River. Using the OLI Landsat images taken on 8 April 2016 (before the flood) and 24 April 2016 (after the flood) the geomorphic effects were detected in different land cover types within the 155-km-long study reach. The results show that the flood significantly affected the channel width and the main effect was high mobilization of channel sediments and severe bank erosion in the meandering reaches. According to field surveys, the flood occupied the channel corridor and even the floodplain parts. However, the channel pattern was not significantly altered, although the results show that the average channel width increased from 192 to 256 m. Statistical results indicate a significant change for active channel width and sinuosity index at 99% confidence level for both indexes. The flood-induced morphological changes varied significantly for different land cover types along the Karoon River. Specifically, the channel has widened less in residential areas than in other land cover types because of the occurrence of bank protection structures. However, the value of bank retreat in residential and protected sides of the Karoon River is more than what we expected during the study of extreme flood.

Geodiversity of a large meander bend in the Little Belt strait in the inner Danish waters

NASA Astrophysics Data System (ADS)

Brandbyge Ernstsen, Verner; Øbro Hansen, Lars; Becker, Marius; Brivio, Lara; Vang, Torben; Lynnerup Trinhammer, Per; Andresen, Katrine Juul; Seidenkrantz, Marit-Solveig; Boldreel, Lars Ole; Bartholdy, Jesper

2017-04-01

The Little Belt strait in the inner Danish waters is characterised by a high biodiversity, and continuous monitoring of flora and fauna and the water quality is undertaken by the authorities. However, the surface sedimentology and geomorphology, i.e. elements of the geodiversity, are less well-constrained. The aim of this study is to investigate the surface sediment and morphology of a large meander bend (with a channel width of 1 km) located between the two bridges crossing the strait (a channel reach of 4 km) in order to assess a potential coupling between geodiversity and biodiversity. More specifically, the objectives are 1) to identify and classify morphological units for creating a geomorphological map, 2) to quantify surface material characteristics for creating a surface material map, and 3) to develop a conceptual model of the substrate and the morphology and morphodynamics in the meander bend between the two bridges in the strait. Preliminary results reveal a diverse morphology in the meander bend; and the annual morphological changes reveal complex sediment transport patterns along and across the bend. Likewise significant sediment sorting trends exist along and across the meander bend. Hence, the preliminary results indicate a high geodiversity in the strait. Acknowledgements The data were collected as part of the MSc course Marine Geoscience, a joint MSc course between the Department of Geosciences and Natural Resource Management at the University of Copenhagen and the Department of Geoscience at Aarhus University. Additional data were included from the research project Control in the Danish Straits 1 (CiDS-1) funded by the Danish Centre for Marine Research (PI Morten Holtegaard). Thanks to the crew on board RV Aurora.

Rivers on Titan - numerical modelling of sedimentary structures

NASA Astrophysics Data System (ADS)

Misiura, Katarzyna; Czechowski, Leszek

2016-07-01

On Titan surface we can expect a few different geomorphological forms, e.g. fluvial valley and river channels. In our research we use numerical model of the river to determine the limits of different fluvial parameters that play important roles in evolution of the rivers on Titan and on Earth. We have found that transport of sediments as suspended load is the main way of transport for Titan [1]. We also determined the range of the river's parameters for which braided river is developed rather than meandering river. Similar, parallel simulations for rivers deltas are presented in [2]. Introduction Titan is a very special body in the Solar System. It is the only moon that has dense atmosphere and flowing liquid on its surface. The Cassini-Huygens mission has found on Titan meandering rivers, and indicated processes of erosion, transport of solid material and its sedimentation. This work is aimed to investigate the similarity and differences between these processes on Titan and the Earth. Numerical model The dynamical analysis of the considered rivers is performed using the package CCHE modified for the specific conditions on Titan. The package is based on the Navier-Stokes equations for depth-integrated two dimensional, turbulent flow and three dimensional convection-diffusion equation of sediment transport. For more information about equations see [1]. Parameters of the model We considered our model for a few different parameters of liquid and material transported by a river. For Titan we consider liquid corresponding to a Titan's rain (75% methane, 25% nitrogen), for Earth, of course, the water. Material transported in rivers on Titan is water ice, for Earth - quartz. Other parameters of our model are: inflow discharge, outflow level, grain size of sediments etc. For every calculation performed for Titan's river similar calculations are performed for terrestrial ones. Results and Conclusions The results of our simulation show the differences in behaviour of the

Hydraulic Characteristics of the Lower Snake River during Periods of Juvenile Fall Chinook Salmon Migration, 2002-2006 Final Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, C.; Dibrani, B.; Richmond, M.

2006-01-01

This report documents a four-year study to assess hydraulic conditions in the lower Snake River. The work was conducted for the Bonneville Power Administration, U.S. Department of Energy, by the Pacific Northwest National Laboratory. Cold water released from the Dworshak Reservoir hypolimnion during mid- to late-summer months cools the Clearwater River far below equilibrium temperature. The volume of released cold water augments the Clearwater River, and the combined total discharge is on the order of the Snake River discharge when the two rivers meet at their confluence near the upstream edge of Lower Granite Reservoir. With typical temperature differences betweenmore » the Clearwater and Snake rivers of 10 C or more during July and August, the density difference between the two rivers during summer flow augmentation periods is sufficient to stratify Lower Granite Reservoir as well as the other three reservoirs downstream. Because cooling of the river is desirable for migrating juvenile fall Chinook salmon (Oncorhynchus tshawytscha) during this same time period, the amount of mixing and cold water entrained into Lower Granite Reservoir's epilimnion at the Clearwater/Snake River confluence is of key biological importance. Data collected during this project indicates the three reservoirs downstream of Lower Granite also stratify as direct result of flow augmentation from Dworshak Reservoir. These four reservoirs are also heavily influenced by wind forcing at the water's surface and during periods of low river discharge often behave like a two-layer lake. During these periods of stratification, lower river discharge, and wind forcing, the water in the upper layer of the reservoir is held in place or moves slightly upstream. This upper layer is also exposed to surface heating and may warm up to temperatures close to equilibrium temperature. The thickness (depth) of this upper warm layer and its direction of travel may be of key biological importance to juvenile fall

Fronts, meanders and eddies in Drake Passage during the ANT-XXIII/3 cruise in January-February 2006: A satellite perspective

NASA Astrophysics Data System (ADS)

Barré, Nicolas; Provost, Christine; Renault, Alice; Sennéchael, Nathalie

2011-12-01

We used satellite altimetric data to provide a context for the results of the ANT-XXIII/3 cruise in January-February 2006 both in time (16 years) and space (the whole of Drake Passage). The repeat of the hydrographical section within 3 weeks permitted different comparisons between the in-situ datasets and the satellite data products. Comparisons suggested that the multi-satellite product improved the temporal resolution on a Jason-1 track. A detailed analysis of the four absolute dynamic topography maps contemporaneous with the ANT-XXIII/3 cruise permitted identification of the location of the frontal branches of the Antarctic Circumpolar Current, of the major meanders and eddies. This spatial context proved particularly valuable for the interpretation of the in-situ data (see companion papers of Provost et al., 2011; Renault et al., 2011; Sudre et al., 2011). The altimetric time-series documented the long-term trends in sea-surface height, the recurrence of major frontal meanders and eddies and the statistical links between them. Negative trends in the Yaghan Basin indicated that both the Subantarctic Front and the Polar Front have shifted to the north of their climatological location. This northward shift in the Yaghan Basin contrasts with the large-scale southward shift in the Polar Front current core described in the literature, and is probably related to the local bottom topography in Drake Passage. Sea-level anomaly patterns observed during the cruise were related to statistical modes of the corresponding variations in Drake Passage. For example, the southward meander of the Subantarctic Front at the entrance to Drake Passage was part of a dipole comprising an adjacent Polar Front meander and occurred with a close to annual periodicity. A census of eddies in the Ona Basin revealed that the spatial distribution of anticyclonic eddies was consistent with generation from a meander of the Polar and Southern ACC Fronts over the Ona Seafloor Depression, while

76 FR 63952 - Notice of Filing of Plats of Survey; Montana

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-14

... Bighorn River, downstream, through section 18, the limits of erosion, the medial lines of two relicted... subdivisional lines, the adjusted original meanders of the former left bank of the Bighorn River, downstream, through section 18, a portion of the meanders of the present right bank of the Bighorn River, downstream...

Movements of adult chinook salmon during spawning migration in a metals-contaminated system, Coeur d'Alene River, Idaho

USGS Publications Warehouse

Goldstein, J.N.; Woodward, D.F.; Farag, A.M.

1999-01-01

Spawning migration of adult male chinook salmon Oncorhynchus tshawytscha was monitored by radio telemetry to determine their response to the presence of metals contamination in the South Fork of the Coeur d'Alene River, Idaho. The North Fork of the Coeur d'Alene River is relatively free of metals contamination and was used as a control. In all, 45 chinook salmon were transported from their natal stream, Wolf Lodge Creek, tagged with radio transmitters, and released in the Coeur d'Alene River 2 km downstream of the confluence of the South Fork and the North Fork of the Coeur d'Alene River. Fixed telemetry receivers were used to monitor the upstream movement of the tagged chinook salmon through the confluence area for 3 weeks after release. During this period, general water quality and metals concentrations were monitored in the study area. Of the 23 chinook salmon observed to move upstream from the release site and through the confluence area, the majority (16 fish, 70%) moved up the North Fork, and only 7 fish (30%) moved up the South Fork, where greater metals concentrations were observed. Our results agree with laboratory findings and suggest that natural fish populations will avoid tributaries with high metals contamination.

Observations of Sand Dune Migration on the Colorado River in Grand Canyon using High-Resolution Multibeam Bathymetry

NASA Astrophysics Data System (ADS)

Kaplinski, M. A.; Buscmobe, D.; Ashley, T.; Tusso, R.; Grams, P. E.; McElroy, B. J.; Mueller, E. R.; Hamill, D.

2015-12-01

Repeat, high-resolution multibeam bathymetric surveys were conducted in March and July 2015 along a reach of the Colorado River in Grand Canyon near the Diamond Creek gage (362 km downstream of Lees Ferry, AZ) to characterize the migration of sand dunes. The surveys were collected as part of a study designed to quantify the relative importance of bedload and suspended sediment transport and develop a predictive relationship for bedload transport. Concurrent measurements of suspended-sediment concentrations, bed-sediment grain size, and water velocity were also collected. The study site is approximately 350 m long and 50 m wide; water depths are 7 to 10 m during normal flows; and a field of sand dunes form along its entire length with negligible coarse material at the bed surface. Full swath coverage of the site required about 6 to 10 minutes to complete with two passes of the survey vessel. Mapping occurred continuously during several survey periods. For each survey period, time-series of bathymetric maps were constructed from each pair of survey lines. In March, surveys were collected over durations of 2, 3, 9, and 11 hours, at discharges of 339 to 382 m3/s. In July, surveys were collected over durations of 4, 4, and 13 hours, at discharges ranging from 481 to 595 ft3/s. These surveys capture the migration of sand dunes over a wide range of discharge with an unprecedented temporal resolution. The dunes in March were between 30 and 50 cm in height, 5 m in length, and migrating downstream at about 1 m per hour. In July, dunes were between 75 and 130 cm in height and 10-15 m in length, and were migrating downstream at rates of 5 to 2 m per hour. The surveys also reveal that the dune migration is spatially and temporally variable, with fast-migrating small dunes variably superimposed on slower-moving larger dunes. The dunes also refract around shoreline talus piles and other flow constrictions collectively causing a large degree of dune deformation as they migrate.

Evolution of fluvial styles in the Eocene Wasatch Formation, Powder River Basin, Wyoming

USGS Publications Warehouse

Warwick, Peter D.; Flores, Romeo M.; Ethridge, Frank G.; Flores, Romeo M.

1987-01-01

Vertical and lateral facies changes in the lower part of the Eocene Wasatch Formation in the Powder River Basin, Wyoming represent an evolution of fluvial systems that varied from meandering to anastomosing. The meandering facies in the lower part of the study interval formed in a series of broad meanderbelts in a northnorthwestflowing system. Upon abandonment this meanderbelt facies served as a topographic high on which a raised or ombrotrophic Felix peat swamp developed. Peat accumulated until compaction permitted encroachment of crevasse splays from an adjoining transitional facies which consists of deposits of a slightly sinuous fluvial system. Crevasse splays eventually prograded over the peat swamp that was partly covered by lakes. Bifurcation, reunification, and transformation of crevasse channels into major conduits produced an anastomosing system that was characterized by diverging and converging channels separated by floodbasins drowned by lakes and partly covered swamps.

Oxbows and Cutoffs in Idaeus Fossae

NASA Image and Video Library

2013-08-21

As rivers age they can meander and occasionally these meanders get so pronounced that the river cuts off these curving loops at their narrow end leaving them as isolated as oxbow lakes. Image from NASA Mars Reconnaissance Orbiter.

Feedbacks Between Bioclogging and Infiltration in Losing River Systems

NASA Astrophysics Data System (ADS)

Newcomer, M. E.; Hubbard, S. S.; Fleckenstein, J. H.; Schmidt, C.; Maier, U.; Thullner, M.; Ulrich, C.; Rubin, Y.

2014-12-01

Reduction in riverbed permeability due to biomass growth is a well-recognized yet poorly understood process associated with losing connected and disconnected rivers. Although several studies have focused on riverbed bioclogging processes at the pore-scale, few studies have quantified bioclogging feedback cycles at the scale relevant for water resources management, or at the meander-scale. At this scale, often competing hydrological-biological processes influence biomass dynamics and infiltration. Disconnection begins when declines in the water table form an unsaturated zone beneath the river maximizing seepage. Simultaneously, bioclogging reduces the point-scale infiltration flux and can either limit the nutrient flux and reduce bioclogging, or preferentially focus infiltration elsewhere and enhance bioclogging. These feedbacks are highly dependent on geomorphology and seasonal patterns of discharge and water temperature. To assess the mutual influences of disconnection, biomass growth, and temperature changes on infiltration in a geomorphologically complex river system, we built a 3D numerical model, conditioned on field data, using the reactive-transport simulator MIN3P. Results show that in disconnected regions of the river, biomass growth reduced vertical seepage downward and extended the unsaturated zone length; however these changes were contingent upon disconnection. Mid-way through the seasonal cycle, biomass declined in these same regions due to limited nutrient flux. Seepage and biomass continued to oscillate with a lag correlation of 1 month. Connected regions, however, showed the largest infiltration rates, nutrient fluxes, and concentrations of biomass. Despite the reduction in conductivity from biomass, flow remains high in connected regions because the feedback between bioclogging and infiltration is not as pronounced due to the sharpening hydraulic gradient. Bioclogging ultimately shapes the pattern of flow, however geomorphology dominates the

Earth Observations taken by Expedition 38 crewmember

NASA Image and Video Library

2013-12-30

ISS038-E-023651 (26 Dec. 2013) --- Lake Sharpe near Lower Brule, South Dakota is featured in this image photographed by an Expedition 38 crew member on the International Space Station. The Missouri River rises in the Rocky Mountains of western Montana, and flows generally to the southeast for approximately 3,767 kilometers (2,341 miles) to its confluence with the Mississippi River north of St. Louis, Missouri -- making it the longest river in North America. The river does not follow a straight southeasterly course along this distance, but includes may meander bends such as illustrated in this photograph. This particular bend is occupied by Lake Sharpe, an approximately 130-kilometer (80 miles) long reservoir formed behind the Big Bend Dam on the Missouri River. The lake surface is frozen and covered with snow, presenting a uniform white appearance in the image. As meander bends develop, they tend to assume a distinctive U-shape when viewed from above. Over time, the river channel can continue to cut into the ends of the "U", eventually bringing them so close together that the river then cuts across the gap to achieve a shorter flow path, essentially short-circuiting or cutting off the meander bend. When this happens and the meander ceases to be part of the active river channel, it may become an oxbow lake. The distance across the narrow neck of land (lower right) associated with this meander near Lower Brule, South Dakota is approximately one kilometer (0.62 miles); however, as the river flow is controlled by the Big Bend Dam downstream, the natural process of meander cutoff has been significantly slowed. The snow cover also highlights circular agricultural fields on the small peninsula within the meander bend. This type of field indicates center-pivot irrigation, where water is distributed from a central point radially outwards using sprinklers to cover the field area. Crops grown here include corn and soybeans according to data from the US Department of

Downstream migration and multiple dam passage by Atlantic Salmon smolts

USGS Publications Warehouse

Nyqvist, D.; McCormick, Stephen; Greenberg, L.; Ardren, W.R.; Bergman, E.; Calles, O.; Castro-Santos, Theodore R.

2017-01-01

The purpose of this study was to investigate behavior and survival of radio-tagged wild and hatchery-reared landlocked Atlantic Salmon Salmo salar smolts as they migrated past three hydropower dams equipped with fish bypass solutions in the Winooski River, Vermont. Among hatchery-reared smolts, those released early were more likely to initiate migration and did so after less delay than those released late. Once migration was initiated, however, the late-released hatchery smolts migrated at greater speeds. Throughout the river system, hatchery-reared fish performed similarly to wild fish. Dam passage rates varied between the three dams and was highest at the dam where unusually high spill levels occurred throughout the study period. Of the 50 fish that did migrate downstream, only 10% managed to reach the lake. Migration success was low despite the presence of bypass solutions, underscoring the need for evaluations of remedial measures; simply constructing a fishway is not synonymous with providing fish passage.

Sulfate migration in a river affected by acid mine drainage from the Dabaoshan mining area, South China.

PubMed

Chen, Meiqin; Lu, Guining; Guo, Chuling; Yang, Chengfang; Wu, Jingxiong; Huang, Weilin; Yee, Nathan; Dang, Zhi

2015-01-01

Sulfate, a major component of acid mine drainage (AMD), its migration in an AMD-affected river which located at the Dabaoshan mine area of South China was investigated to pursue the remediation strategy. The existing factors of relatively low pH values of 2.8-3.9, high concentrations of SO4(2-) (∼1940 mg L(-1)) and Fe(3+) (∼112 mg L(-1)) facilitated the precipitation of schwertmannite (Fe8O8(OH)6SO4·nH2O) in the upstream river. Geochemical model calculations implied the river waters were supersaturated, creating the potential for precipitation of iron oxyhydroxides. These minerals evolved from schwertmannite to goethite with the increasing pH from 2.8 to 5.8 along the river. The concentration of heavy metals in river waters was great reduced as a result of precipitation effects. The large size of the exchangeable sulfate pool suggested that the sediments had a strong capacity to bind SO4(2-). The XRD results indicated that schwertmannite was the predominant form of sulfate-bearing mineral phases, which was likely to act as a major sulfate sink by incorporating water-borne sulfate into its internal structure and adsorbing it onto its surface. The small size of reduced sulfur pools and strong oxidative status in the surface sediments further showed that SO4(2-) shifting from water to sediment in form of sulfate reduction was not activated. In short, precipitation of sulfate-rich iron oxyhydroxides and subsequent SO4(2-) adsorption on these minerals as well as water dilution contributed to the attenuation of SO4(2-) along the river waters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Errors in Martian paleodischarges skew interpretations of hydrologic history: Case study of the Aeolis Dorsa, Mars, with insights from the Quinn River, NV

NASA Astrophysics Data System (ADS)

Jacobsen, Robert E.; Burr, Devon M.

2018-03-01

Changes in Martian fluvial geomorphology with time-stratigraphic age, including decreases in paleochannel widths, suggest waning paleodischarges through time. Where fluvial landforms do not preserve paleochannel widths (e.g., meander deposits), other landform dimensions (i.e., radius of curvature) may be used to estimate paleodischarges. In the Aeolis Dorsa region, topographically inverted and stacked fluvial deposits - wide meander point bars overlain by thin channel fills - preserve ostensible evidence of decreasing paleodischarges through time. However, a robust paleohydraulic analysis of these distinct deposits requires knowledge of the accuracy of a terrestrial-based empirical relationship that estimates channel width from point-bar radius of curvature. We assess the accuracy of this radius-width relationship by applying it to a well-studied terrestrial analog, the Quinn River, Nevada. We find that radii of curvature from the Quinn River exceed the values predicted from the empirical relationship. These anomalously high radii are associated with greater resistance in the channel cut banks, indicating that bank strength is a confounding factor in the radius-width relationship. Some deposits in the Aeolis Dorsa include irregular meander morphologies, suggesting variably resistant channel banks and overestimates of both paleochannel widths and paleodischarges. Furthermore, the morphometry of the overlying thin channel fills suggests their widths have been eroded, such that their paleodischarges are underestimates. These overestimates and underestimates, when considered together, suggest little change in paleodischarge during the stratigraphic transition from meander deposits to channel fills. This work demonstrates the importance of terrestrial analog studies for revealing confounding factors in Martian fluvial systems and cautions against simplistic interpretations of Martian fluvial history. The discovered inaccuracies of paleodischarge estimates expose sources

Electro-optic phase matching in a Si photonic crystal slow light modulator using meander-line electrodes.

PubMed

Hinakura, Yosuke; Terada, Yosuke; Arai, Hiroyuki; Baba, Toshihiko

2018-04-30

We demonstrate a Si photonic crystal waveguide Mach-Zehnder modulator that incorporates meander-line electrodes to compensate for the phase mismatch between slow light and RF signals. We first employed commonized ground electrodes in the modulator to suppress undesired fluctuations in the electro-optic (EO) response due to coupled slot-line modes of RF signals. Then, we theoretically and experimentally investigated the effect of the phase mismatch on the EO response. We confirmed that meander-line electrodes improve the EO response, particularly in the absence of internal reflection of the RF signals. The cut-off frequency of this device can reach 27 GHz, which allows high-speed modulation up to 50 Gbps.

Comparative ontogenetic behavior and migration of kaluga, Huso dauricus, and Amur sturgeon, Acipenser schrenckii, from the Amur River

USGS Publications Warehouse

Zhuang, P.; Kynard, B.; Zhang, L.; Zhang, T.; Cao, W.

2003-01-01

We conducted laboratory experiments with kaluga, Huso dauricus, and Amur sturgeon, Acipenser schrenckii, to develop a conceptual model of early behavior. We daily observed embryos (first life phase after hatching) and larvae (period initiating exogenous feeding) to day-30 (late larvae) for preference of bright habitat and cover, swimming distance above the bottom, up- and downstream movement, and diel activity. Day-0 embryos of both species strongly preferred bright, open habitat and initiated a strong, downstream migration that lasted 4 days (3 day peak) for kaluga and 3 days (2 day peak) for Amur sturgeon. Kaluga migrants swam far above the bottom (150 cm) on only 1 day and moved day and night; Amur sturgeon migrants swam far above the bottom (median 130 cm) during 3 days and were more nocturnal than kaluga. Post-migrant embryos of both species moved day and night, but Amur sturgeon used dark, cover habitat and swam closer to the bottom than kaluga. The larva period of both species began on day 7 (cumulative temperature degree-days, 192.0 for kaluga and 171.5 for Amur sturgeon). Larvae of both species preferred open habitat. Kaluga larvae strongly preferred bright habitat, initially swam far above the bottom (median 50-105 cm), and migrated downstream at night during days 10-16 (7-day migration). Amur sturgeon larvae strongly avoided illumination, had a mixed response to white substrate, swam 20-30 cm above the bottom during most days, and during days 12-34 (most of the larva period) moved downstream mostly at night (23-day migration). The embryo-larva migration style of the two species likely shows convergence of non-related species for a common style in response to environmental selection in the Amur River. The embryo-larva migration style of Amur sturgeon is unique among Acipenser yet studied.

Spring migration of mallards from Arkansas as determined by satellite telemetry

USGS Publications Warehouse

Krementz, David G.; Asante, Kwasi; Naylor, L.M.

2011-01-01

We used satellite telemetry to document spring migration phenology, routes, stopover regions, and nesting sites of mallards Anas platyrhynchos marked in Arkansas during the winters of 2004-2007. Of the 143 marked mallards that migrated from Arkansas, they did so, on average, by mid-March. Mallards flew over the Missouri Ozarks and 42% made an initial stopover in Missouri, where they used areas that had larger rivers (Mississippi River, Missouri River) embedded in an agricultural landscape. From this stopover region they either migrated directly to the Prairie Pothole Region (PPR) or they migrated north to Minnesota where they either moved next to the PPR or to the north and east of the PPR. For those mallards (83%) that stopped for >1 d before entering the PPR, the average length at each stop was 12 d (SE = 0.90 d, range = 2-54 d). Mallards made more stopovers, made shorter migration movements, and took longer to move to the PPR in wetter than drier years. Mallards arrived in the PPR earlier in 2006 x- = 30 March, SE = 2.18 d) than in 2005 x- = 7 April, SE = 2.30 d). Females nested across nine Bird Conservation Regions. Nesting occurred most frequently in South Dakota (n = 9). The average date when females nested was 19 April (SE = 2.44 d, range = 12 March-26 May). Because many mallards headed for the large river corridors in Missouri for their first stopover, this region is an important spring migration stopover of continental importance to mallards and might be considered a focal area for conservation.

Abundance, Timing of Migration, and Egg-to-Smolt Survival of Juvenile Chum Salmon, Kwethluk River, Alaska, 2007 and 2008

USGS Publications Warehouse

Burril, Sean E.; Zimmerman, Christian E.; Finn, James E.; ,; Gillikin, Daniel; ,

2010-01-01

To better understand and partition mortality among life stages of chum salmon (Oncorhynchus keta), we used inclined-plane traps to monitor the migration of juveniles in the Kwethluk River, Alaska in 2007 and 2008. The migration of juvenile chum salmon peaked in mid-May and catch rates were greatest when water levels were rising. Movement of chum salmon was diurnal with highest catch rates occurring during the hours of low light (that is, 22:00 to 10:00). Trap efficiency ranged from 0.37 to 4.04 percent (overall efficiency = 1.94 percent). Total abundance of juvenile chum salmon was estimated to be 2.0 million fish in 2007 and 2.9 million fish in 2008. On the basis of the estimate of chum salmon females passing the Kwethluk River weir and age-specific fecundity, we estimated the potential egg deposition (PED) upstream of the weir and trapping site. Egg-to-smolt survival, calculated by dividing the estimate of juvenile chum salmon emigrating past the weir site by the estimate of PED, was 4.6 percent in 2007 and 5.2 percent in 2008. In addition to chum salmon, Chinook salmon O. tshawytscha), coho salmon (O. kisutch), sockeye salmon (O. nerka), and pink salmon (O. gorbuscha), as well as ten other fish species, were captured in the traps. As with chum salmon, catch of these species increased during periods of increasing discharge and peaked during hours of low light. This study successfully determined the characteristics of juvenile salmon migrations and estimated egg-to-smolt survival for chum salmon. This is the first estimate of survival for any juvenile salmon in the Arctic-Yukon-Kuskokwim region of Alaska and demonstrates an approach that can help to partition mortality between freshwater and marine life stages, information critical to understanding the dynamics of salmon in this region.

Linking hydro-morphology with invertebrate ecology in diverse morphological units of a large river-floodplain system

NASA Astrophysics Data System (ADS)

Blettler, Martín. C. M.; Amsler, Mario L.; Eberle, Eliana G.; Szupiany, Ricardo; Latosinski, Francisco G.; Abrial, Elie; Oberholster, Paul J.; Espinola, Luis A.; Paira, Aldo; Poza, Ailen; Rodrigues Capítulo, Alberto

2016-12-01

Interdisciplinary research in the fields of ecohydrology and ecogeomorphology is becoming increasingly important as a way to understand how biological and physical processes interact with each other in river systems. The objectives of the current study were 1) to determine changes in invertebrate community due to hydrological stages, 2) to link local physical features [flow configuration, sediment composition and morphological feature) with the ecological structure between and within dissimilar morphological units (meander and confluence), and 3) to determine the existence and the origin of bed hydro-geomorphic patches, determining their ecological structure. Results were discussed in the frame of prevailing ecological models and concepts. The study site extends over a floodplain area of the large Paraná River (Argentina), including minor and major secondary channels as well as the main channel. Overall results suggested that hydrodynamics was the driving force determining distribution patterns of benthic assemblages in the floodplain. However, while the invertebrates living in minor secondary channels seem to benefit from flooding, this hydrological phase had the opposite effect on organisms from the main and major secondary channels. We also found a clear linkage between physical features and invertebrate ecology, which caused a dissimilar fauna structure between and within the meander and the confluence. Furthermore, several sandy-patches were recorded in the confluence. These patches were colonized by the particular benthic assemblage recorded in the main channel, supported the view of rivers as patchy discontinua, under uncertain ecological equilibrium.

Freedom space for rivers: An economically viable river management concept in a changing climate

NASA Astrophysics Data System (ADS)

Buffin-Bélanger, Thomas; Biron, Pascale M.; Larocque, Marie; Demers, Sylvio; Olsen, Taylor; Choné, Guénolé; Ouellet, Marie-Audray; Cloutier, Claude-André; Desjarlais, Claude; Eyquem, Joanna

2015-12-01

The freedom space concept applies hydrogeomorphic principles to delineate zones that are either frequently flooded or actively eroding, or that include riparian wetlands. Freedom space limits mapped for three rivers in southern Quebec (Canada) were assessed to determine whether they would still be valid under a future climate using a sensitivity analysis approach with numerical models predicting mobility of meanders (RVRMeander) and flood stage (HEC-RAS). The freedom space limits were also used in a cost-benefit analysis over a 50-year period where costs consist of loss or limitations to the right of farming and construction in this zone, whereas benefits are avoided costs for existing or future bank stabilization structures and avoided costs of flooding in agricultural areas. The economic value of ecosystem services provided by riparian wetlands and increased buffer zones within the freedom space were also included in the analysis. Results show that freedom space limits would be robust in future climate, and show net present values ranging from CDN0.7 to 3.7 million for the three rivers, with ratios of benefits over costs ranging between 1.5:1 and 4.8:1. River management based on freedom space is thus beneficial for society over a 50-year period.

Quantifying geomorphic controls on riparian forest dynamics using a linked physical-biological model: implications for river corridor conservation

NASA Astrophysics Data System (ADS)

Stella, J. C.; Harper, E. B.; Fremier, A. K.; Hayden, M. K.; Battles, J. J.

2009-12-01

In high-order alluvial river systems, physical factors of flooding and channel migration are particularly important drivers of riparian forest dynamics because they regulate habitat creation, resource fluxes of water, nutrients and light that are critical for growth, and mortality from fluvial disturbance. Predicting vegetation composition and dynamics at individual sites in this setting is challenging, both because of the stochastic nature of the flood regime and the spatial variability of flood events. Ecological models that correlate environmental factors with species’ occurrence and abundance (e.g., ’niche models’) often work well in infrequently-disturbed upland habitats, but are less useful in river corridors and other dynamic zones where environmental conditions fluctuate greatly and selection pressures on disturbance-adapted organisms are complex. In an effort to help conserve critical riparian forest habitat along the middle Sacramento River, CA, we are taking a mechanistic approach to quantify linkages between fluvial and biotic processes for Fremont cottonwood (Populus fremontii), a keystone pioneer tree in dryland rivers ecosystems of the U.S. Southwest. To predict the corridor-wide population effects of projected changes to the disturbance regime from flow regulation, climate change, and landscape modifications, we have coupled a physical model of channel meandering with a patch-based population model that incorporates the climatic, hydrologic, and topographic factors critical for tree recruitment and survival. We employed these linked simulations to study the relative influence of the two most critical habitat types--point bars and abandoned channels--in sustaining the corridor-wide cottonwood population over a 175-year period. The physical model uses discharge data and channel planform to predict the spatial distribution of new habitat patches; the population model runs on top of this physical template to track tree colonization and survival on

Distribution and migration mechanism of fluoride in groundwater in the Manas River Basin, Northwest China

NASA Astrophysics Data System (ADS)

Liu, Yalei; Jin, Menggui; Ma, Bin; Wang, Jianjun

2018-04-01

Elevated fluoride (F) concentration in groundwater is posing a public health risk in the Manas River Basin (MRB), Northwest China. Based on the characterization of regional groundwater flow, 90 groundwater samples from aquifers were analyzed, along with top-soil leachate and pore-water samples from aquitards. Stable oxygen (δ18O) and hydrogen isotopes, radiocarbon and hydrochemical analyses of the groundwater and pore-water samples were conducted to trace groundwater hydrological and hydrochemical processes and thereby understand the distribution and migration mechanism of F. The groundwater is recharged by meteoric precipitation through vapor condensation processes in the Tianshan Mountains. The F concentration in groundwater samples from this basin ranged from 0.11 to 48.15 mg/L (mean 2.56 mg/L). In 37 of the 90 groundwater samples, the F concentrations were above the safe level for drinking water. The F concentrations progressively increased with the residence time and well depths in the northwest of the alluvial-fluvial plain, where groundwater is overexploited for agricultural and domestic use. Positive correlations between F and sodium (Na)/calcium (Ca) indicate that the enrichment and migration of F are influenced by cation exchange processes under high-Na and alkaline pH conditions. The relationships between δ18O and F and chloride (Cl) concentrations were nonlinear due to leaching and mixing processes. This shows that vertical leaching by irrigation return flow and mixing with pore water are the dominant processes driving the migration of F in the groundwater flow system of MRB, in addition to geochemical processes.

Simulating the Effects of Sea Level Rise on the Resilience and Migration of Tidal Wetlands along the Hudson River

PubMed Central

Tabak, Nava M.; Laba, Magdeline; Spector, Sacha

2016-01-01

Sea Level Rise (SLR) caused by climate change is impacting coastal wetlands around the globe. Due to their distinctive biophysical characteristics and unique plant communities, freshwater tidal wetlands are expected to exhibit a different response to SLR as compared with the better studied salt marshes. In this study we employed the Sea Level Affecting Marshes Model (SLAMM), which simulates regional- or local-scale changes in tidal wetland habitats in response to SLR, and adapted it for application in a freshwater-dominated tidal river system, the Hudson River Estuary. Using regionally-specific estimated ranges of SLR and accretion rates, we produced simulations for a spectrum of possible future wetland distributions and quantified the projected wetland resilience, migration or loss in the HRE through the end of the 21st century. Projections of total wetland extent and migration were more strongly determined by the rate of SLR than the rate of accretion. Surprisingly, an increase in net tidal wetland area was projected under all scenarios, with newly-formed tidal wetlands expected to comprise at least 33% of the HRE’s wetland area by year 2100. Model simulations with high rates of SLR and/or low rates of accretion resulted in broad shifts in wetland composition with widespread conversion of high marsh habitat to low marsh, tidal flat or permanent inundation. Wetland expansion and resilience were not equally distributed through the estuary, with just three of 48 primary wetland areas encompassing >50% of projected new wetland by the year 2100. Our results open an avenue for improving predictive models of the response of freshwater tidal wetlands to sea level rise, and broadly inform the planning of conservation measures of this critical resource in the Hudson River Estuary. PMID:27043136

Simulating the Effects of Sea Level Rise on the Resilience and Migration of Tidal Wetlands along the Hudson River.

PubMed

Tabak, Nava M; Laba, Magdeline; Spector, Sacha

2016-01-01

Sea Level Rise (SLR) caused by climate change is impacting coastal wetlands around the globe. Due to their distinctive biophysical characteristics and unique plant communities, freshwater tidal wetlands are expected to exhibit a different response to SLR as compared with the better studied salt marshes. In this study we employed the Sea Level Affecting Marshes Model (SLAMM), which simulates regional- or local-scale changes in tidal wetland habitats in response to SLR, and adapted it for application in a freshwater-dominated tidal river system, the Hudson River Estuary. Using regionally-specific estimated ranges of SLR and accretion rates, we produced simulations for a spectrum of possible future wetland distributions and quantified the projected wetland resilience, migration or loss in the HRE through the end of the 21st century. Projections of total wetland extent and migration were more strongly determined by the rate of SLR than the rate of accretion. Surprisingly, an increase in net tidal wetland area was projected under all scenarios, with newly-formed tidal wetlands expected to comprise at least 33% of the HRE's wetland area by year 2100. Model simulations with high rates of SLR and/or low rates of accretion resulted in broad shifts in wetland composition with widespread conversion of high marsh habitat to low marsh, tidal flat or permanent inundation. Wetland expansion and resilience were not equally distributed through the estuary, with just three of 48 primary wetland areas encompassing >50% of projected new wetland by the year 2100. Our results open an avenue for improving predictive models of the response of freshwater tidal wetlands to sea level rise, and broadly inform the planning of conservation measures of this critical resource in the Hudson River Estuary.

Double-crested cormorants along the upper Mississippi River

USGS Publications Warehouse

Kirsch, E.M.

1995-01-01

The Upper Mississippi River is an important habitat corridor for migratory birds and other wildlife, and it supports an important commercial and sport fishery. A study was initiated by the U.S. Fish and Wildlife Service in 1991 to describe Double-crested cormorant (Phalacrocorax auritus) distribution and abundance on the Upper Mississippi River throughout the year to better understand the possible impacts of cormorants on fish resources and populations of other piscivorous birds. Double-crested Cormorants were common breeders and abundant during migration on the Upper Mississippi River during the 1940s. Numbers of cormorants declined in the 1960s and 1970s along the Upper Mississippi River as they did in other parts of the United States. In 1992, 418 cormorant pairs were estimated to have nested in four colonies on the Upper Mississippi River, and less than 7,000 cormorants were estimated to have migrated along the river during the fall and spring of 1991 and 1992. Recent public concern for fish resources has grown with a perceived growth of the local cormorant population. Migrating cormorants collected on the Upper Mississippi River took Gizzard Shad (Dorosoma cepedianum) primarily, but chicks were fed a wide variety of fish species.

Comparison of migration rate and survival between radio-tagged and PIT-tagged migrant yearling chinook salmon in the Snake and Columbia rivers

USGS Publications Warehouse

Hockersmith, E.E.; Muir, W.D.; Smith, S.G.; Sandford, B.P.; Perry, R.W.; Adams, N.S.; Rondorf, D.W.

2003-01-01

A study was conducted to compare the travel times, detection probabilities, and survival of migrant hatchery-reared yearling chinook salmon Oncorhynchus tshawytscha tagged with either gastrically or surgically implanted sham radio tags (with an imbedded passive integrated transponder [PIT] tag) with those of their cohorts tagged only with PIT tags in the Snake and Columbia rivers. Juvenile chinook salmon with gastrically implanted radio tags migrated significantly faster than either surgically radio-tagged or PIT-tagged fish, while migration rates were similar among surgically radio-tagged and PIT-tagged fish. The probabilities of PIT tag detection at downstream dams varied by less than 5% and were not significantly different among the three groups. Survival was similar among treatments for median travel times of less than approximately 6 d (migration distance of 106 km). However, for both gastrically and surgically radio-tagged fish, survival was significantly less than for PIT-tagged fish, for which median travel times exceeded approximately 10 d (migration distance of 225 km). The results of this study support the use of radio tags to estimate the survival of juvenile chinook salmon having a median fork length of approximately 150 mm (range, 127-285 mm) and a median travel time of migration of less than approximately 6 d.

Numerical modelling of sedimentary structures in rivers on Titan and Earth

NASA Astrophysics Data System (ADS)

Misiura, Katarzyna; Czechowski, Leszek

2016-04-01

On Titan surface we can expect a few different geomorphological forms, e.g. fluvial valley and river channels. In our research we use numerical model of the river to determine the limits of different fluvial parameters that play important roles in evolution of the rivers on Titan and on Earth. We have found that transport of sediments as suspended load is the main way of transport for Titan. We also determined the range of the river's parameters for which braided river is developed rather than meandering river. 2. Introduction Titan is a very special body in the Solar System. It is the only moon that has dense atmosphere and flowing liquid on its surface. The Cassini-Huygens mission has found on Titan meandering rivers, and indicated processes of erosion, transport of solid material and its sedimentation. This work is aimed to investigate the similarity and differences between these processes on Titan and the Earth. 3. Numerical model The dynamical analysis of the considered rivers is performed using the package CCHE modified for the specific conditions on Titan. The package is based on the Navier-Stokes equations for depth-integrated two dimensional, turbulent flow and three dimensional convection-diffusion equation of sediment transport. For more information about equations see [1]. 4. Parameters of the model We considered our model for a few different parameters of liquid and material transported by a river. For Titan we consider liquid corresponding to a Titan's rain (75% methane, 25% nitrogen), for Earth, of course, the water. Material transported in rivers on Titan is water ice, for Earth - quartz. Other parameters of our model are: inflow discharge, outflow level, grain size of sediments etc. For every calculation performed for Titan's river similar calculations are performed for terrestrial ones. 5. Results and Conclusions The results of our simulation show the differences in behaviour of the flow and of sedimentation on Titan and on the Earth. Our

Fine sediment trapping in river lateral cavities

NASA Astrophysics Data System (ADS)

Juez, C.; Maechler, G.; Schleiss, A. J.; Franca, M. J.

2016-12-01

River restoration is nowadays a major issue in the field of hydraulics. The natural course and geometry of the rivers have been artificially changed by human activities for different purposes (land gaining, flood protection, agriculture). From a morphologic point of view, channelized rivers often display a straight path and monotonous river banks. This is in contradiction with natural morphology, where a high diversity can be found across the channel path (meanders) and the banks (pools, riffles). One way to restore rivers consist of transforming the artificial banks by adding macro-roughness elements in the lateral river banks (also called cavities and lateral embayments). The creation of irregularities on the banks causes new flow patterns that diversify the river habitat. However, these lateral cavities may be also responsible of the change of the river morphology, since they may trap the fine sediments travelling within the water. This is particularly important in glacier-fed streams such as the upper Rhone River in Switzerland. These are charged with fine sediments resulting from the erosion of the underlying glaciers bottom. The creation of lateral cavities may affect the sediment and morphological equilibrium of the river since these may trap sediments. This work aims to study the influence of the lateral cavities on the transport of fine sediments in the main channel. A set of laboratory experiments were done which covered a wide range of rectangular cavity configurations. Key parameters such as the flow discharge, the aspect ratio of the cavities and the initial sediment concentration were tested. Surface PIV, sediment samples and turbidity temporal records were collected during the experiments. The trapping efficiency of the cavities and the associated flow patterns were analyzed. The resulting conclusions provide a useful information for the future design of river restoration projects.

Exploring pre-channelization bar and planform dynamics of a large regulated Alpine River

NASA Astrophysics Data System (ADS)

Zen, Simone; Zolezzi, Guido; Scorpio, Vittoria; Mastronunzio, Marco; Bertoldi, Walter; Comiti, Francesco; Daiprà, Elena

2017-04-01

As a consequence of heavy channelization mostly carried out in the 1800s, the planform and bars morphodynamics of many large European rivers is hardly detectable even from aerial images dating back several decades, because of the marked reduction of the channel width and of the related morphological complexity. However, when available, historical maps can provide quantitative information on the morphology that characterized these rivers before massive human intervention occurred. In this work we focus on a 100 km reach of the Adige - Etsch River, NE, Italy, with the aim of exploring the short-term (some decades) morphological dynamics that might have characterized the pre-channelized river bed and planform in its single-thread reaches before heavy human intervention. To this aim we integrate the application of a morphodynamic analytical model for meandering rivers with irregularly varying curvature and channel width with the multi-temporal analysis of pre-channelization historical maps. The work focuses on the sinuous and meandering reaches once characterized by spatially varying channel width, and presence of alternate, point and mid-channel bars. Challenges in such kind of integrated analysis are posed by the reconstruction of channel - forming streamflow values and of sediment size that may have characterized the river reaches up to nearly three centuries ago prior to heavy regulation. Formative discharge ranges have been obtained as those generating the best geometrical fit between the modeled river bed morphology and the one observed from the maps. Once calibrated by this procedure, the model was fed through the estimated discharge value to compute the longitudinal variability of the outer-bank shear stress, as a proxy for the locations potentially affected by fluvial bank erosion. The historical maps reveal that during the 17th and 18th century, before the massive channelization, the river morphodynamics was already far from being "natural", especially

Characteristics of Drainage Divide Migration through Coseismic and Storm-Triggered Landslides

NASA Astrophysics Data System (ADS)

Dahlquist, M. P.; West, A. J.; Li, G.

2016-12-01

Drainage basin reorganization is a fundamental but poorly understood process in landscape evolution. Capture and loss of drainage area by rivers redistributes erosive power and can drive the response of a landscape to tectonic/climatic forcing. Evidence of discrete capture of tributaries is widespread and common, but study of gradual migration of divides by hillslope processes (e.g. landsliding) has been minimal. Much scholarship is devoted to the geometric characteristics of rivers as they respond to tectonic forces, and divide migration has been proposed to result from contrasts in fluvial channel form. However, fluvial processes do not extend to basin divides, so fluvial controls on drainage reorganization should be mediated by hillslope processes such as slope failure. Here we explore whether the mediating role of hillslopes can be observed over the timescale of a single earthquake or major storm. We examine landslides in steep landscapes caused by three major events in the past decade: the 2008 Mw 7.9 Wenchuan earthquake in Sichuan, China, the 2009 Typhoon Morakot in Taiwan, and the 2015 Mw 7.8 Gorkha earthquake in Nepal. These events generated landslides that cut off ridges, causing area gain and loss in the drainage basins outlined by those ridges. We compare the location of these ridge-cutting landslides to values of Χ, an integral value of upstream drainage area over the length of a river. Comparing the Χ values of rivers which share a drainage divide is thought to show which river is likely to gain area at the expense of the other as the divide migrates, defining an "aggressor" (smaller Χ at divide) and a "victim" (greater Χ). We compute Χ for the rivers draining ridge-cutting landslides and consider whether landslides favor drainage area gain in basins with lower X values. Our preliminary results suggest that divide migration in areas with small to moderate disparities in Χ appears to be stochastic, with divides frequently migrating in the opposite

Topographical change caused by moderate and small floods in a gravel bed ephemeral river - a depth-averaged morphodynamic simulation approach

NASA Astrophysics Data System (ADS)

Lotsari, Eliisa S.; Calle, Mikel; Benito, Gerardo; Kukko, Antero; Kaartinen, Harri; Hyyppä, Juha; Hyyppä, Hannu; Alho, Petteri

2018-03-01

In ephemeral rivers, channel morphology represents a snapshot at the end of a succession of geomorphic changes caused by floods. In most cases, the channel shape and bedform migration during different phases of a flood hydrograph cannot be identified from field evidence. This paper analyses the timing of riverbed erosion and deposition of a gravel bed ephemeral river channel (Rambla de la Viuda, Spain) during consecutive and moderate- (March 2013) and low-magnitude (May 2013) discharge events, by applying a morphodynamic model (Delft3D) calibrated with pre- and post-event surveys by RTK-GPS points and mobile laser scanning. The study reach is mainly depositional and all bedload sediment supplied from adjacent upstream areas is trapped in the study segment forming gravel lobes. Therefore, estimates of total bedload sediment mass balance can be obtained from pre- and post-field survey for each flood event. The spatially varying grain size data and transport equations were the most important factors for model calibration, in addition to flow discharge. The channel acted as a braided channel during the lower flows of the two discharge events, but when bars were submerged in the high discharges of May 2013, the high fluid forces followed a meandering river planform. The model results showed that erosion and deposition were in total greater during the long-lasting receding phase than during the rising phase of the flood hydrographs. In the case of the moderate-magnitude discharge event, deposition and erosion peaks were predicted to occur at the beginning of the hydrograph, whereas deposition dominated throughout the event. Conversely, the low-magnitude discharge event only experienced the peak of channel changes after the discharge peak. Thus, both type of discharge events highlight the importance of receding phase for this type of gravel bed ephemeral river channel.

Bifurcation and stability analysis of rotating chemical spirals in circular domains: Boundary-induced meandering and stabilization

NASA Astrophysics Data System (ADS)

Bär, Markus; Bangia, Anil K.; Kevrekidis, Ioannis G.

2003-05-01

Recent experimental and model studies have revealed that the domain size may strongly influence the dynamics of rotating spirals in two-dimensional pattern forming chemical reactions. Hartmann et al. [Phys. Rev. Lett. 76, 1384 (1996)], report a frequency increase of spirals in circular domains with diameters substantially smaller than the spiral wavelength in a large domain for the catalytic NO+CO reaction on a microstructured platinum surface. Accompanying simulations with a simple reaction-diffusion system reproduced the behavior. Here, we supplement these studies by a numerical bifurcation and stability analysis of rotating spirals in a simple activator-inhibitor model. The problem is solved in a corotating frame of reference. No-flux conditions are imposed at the boundary of the circular domain. At large domain sizes, eigenvalues and eigenvectors very close to those corresponding to infinite medium translational invariance are observed. Upon decrease of domain size, we observe a simultaneous change in the rotation frequency and a deviation of these eigenvalues from being neutrally stable (zero real part). The latter phenomenon indicates that the translation symmetry of the spiral solution is appreciably broken due to the interaction with the (now nearby) wall. Various dynamical regimes are found: first, the spiral simply tries to avoid the boundary and its tip moves towards the center of the circular domain corresponding to a negative real part of the “translational” eigenvalues. This effect is noticeable at a domain radius of Rmeandering motion, which may be characterized as boundary-induced spiral meandering. A systematic study of the spiral rotation as a function of a control parameter and the domain size reveals that the meandering instability in large domains becomes suppressed, and the spiral rotation becomes rigid, at a critical radius Rcr,0. Boundary

Morphodynamic modeling of the river pattern continuum (Invited)

NASA Astrophysics Data System (ADS)

Nicholas, A. P.

2013-12-01

Numerical models provide valuable tools for integrating understanding of fluvial processes and morphology. Moreover, they have considerable potential for use in investigating river responses to environmental change and catchment management, and for aiding the interpretation of alluvial deposits and landforms. For this potential to be realised fully, such models must be capable of representing diverse river styles and the spatial and temporal transitions between styles that are driven by changes in environmental forcing. However, while numerical modeling of rivers has advanced considerable over the past few decades, this has been accomplished largely by developing separate approaches to modeling single and multi-thread channels. Results are presented here from numerical simulations undertaken using a new model of river and floodplain co-evolution, applied to investigate the morphodynamics of large sand-bed rivers. This model solves the two-dimensional depth-averaged shallow water equations using a Godunov-type finite volume scheme, with a two-fraction representation of sediment transport, and includes the effects of secondary circulation, bank erosion and floodplain development due to the colonization of bar surfaces by vegetation. Simulation results demonstrate the feasibility of representing a wide range of fluvial styles (including braiding, meandering and anabranching channels) using relatively simple physics-based models, and provide insight into the controls on channel pattern diversity in large sand-bed rivers. Analysis of model sensitivity illustrates the important role of upstream boundary conditions as a control on channel dynamics. Moreover, this analysis highlights key uncertainties in model process representation and their implications for modelling river evolution in response to natural and anthropogenic-induced river disturbance.

Decadal changes in channel morphology of a freely meandering river—Powder River, Montana, 1975–2016

USGS Publications Warehouse

Moody, John A.; Meade, Robert H.

2018-03-19

Few studies exist on the long-term geomorphic effects of floods. However, the U.S. Geological Survey (USGS) was able to begin such a study after a 50-year recurrence interval flood in 1978 because 20 channel cross sections along a 100-kilometer reach of river were established in 1975 and 1977 as part of a study for a proposed dam on Powder River in southeastern Montana. These cross-section measurements (data for each channel cross section are available at the USGS ScienceBase website) have been repeated about 30 times during four decades (1975–2016) and provide a unique dataset for understanding long-term changes in channel morphology caused by an extreme flood and a spectrum of annual floods.Changes in channel morphology of a 100-kilometer reach of Powder River are documented in a series of narratives for each channel cross section that include a time series of photographs as a record of these changes. The primary change during the first decade (1975–85) was the rapid vertical growth of a new inset flood plain within the flood-widened channel. Changes during the second decade (1985–95) were characterized by slower growth of the flood plain, and the effects of ice-jam floods typical of a northward-flowing river. Changes during the third decade (1995–2005) showed little vertical growth of the inset flood plain, which had reached a height that limited overbank deposition. And changes during the final decade (2005–16) covered in this report showed that, because the new inset flood plain had reached a limiting height, the effects of the large annual flood of 2008 (largest flood since 1978) were relatively small compared to smaller floods in previous decades. Throughout these four decades, the riparian vegetation, which interacts with the river, has undergone a gradual but substantial change that may have lasting effects on the channel morphology.

Seismic patterns and migration history of submarine fan channels in deep-water area, Niger Delta, West Africa

NASA Astrophysics Data System (ADS)

Zhang, Guotao; Zhang, Shangfeng; Li, Yuan

2015-04-01

The channels of deep-water submarine fan under Niger delta slope are characterized by large dimensions special deposition positions and complex formation processes, its geographical location and sedimentary environment also hinder the research and exploration development. According to the strata slicing, RMS amplitude attribute and other techniques, we exhibit the platforms patterns of channels at different period, and based on the analysis of internal architecture and deformation history of channel-leveed systems, migration and evolution process of channel systems could be understood accurately. A great quantity of isolated channels develop in middle Miocene and aggrading streams in late Miocene, which generating because of large scale of turbidity caused by the drop of second order sea-level, which characterized by vertical accretion at smooth channel, while vertical accretion and lateral migration at bend. Evolution of channel systems can be divided into three stages: the initial erosion, erosion and filling alternately, and abandoned stage. With these three stages, the sinuosity of channel change from moderate to high, then decrease. Incision and filling of channels, being during the three development phases, is the driving force of meander-loops migration, which promote three kinds of migration patterns: lateral, down-system and combination migration. The research provides theoretical basis for high-precision prediction and evaluation of deep-water reservoir.

Defect images by planar ECT probe of meander-mesh coils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamada, Sotoshi; Katou, Masaki; Iwahara, Masayoshi

1996-09-01

This paper presents results pertaining to image data obtained from a planar meander-mesh coupled coil type ECT probe. The image data makes it possible to detect not only the existence of a defect but also to extract detailed information regarding the nature of the defect, such as its position, shape, length, and direction. In order to recognize a defect distinctly, the authors have fabricated the high sensitive planar coil which can be used to image a 2-D representation of the ECT signal. The relationships between the image pattern and defect shape are discussed.

Chlorinated river and lake water extract caused oxidative damage, DNA migration and cytotoxicity in human cells.

PubMed

Yuan, Jing; Wu, Xin-Jiang; Lu, Wen-Qing; Cheng, Xiao-Li; Chen, Dan; Li, Xiao-Yan; Liu, Ai-Lin; Wu, Jian-Jun; Xie, Hong; Stahl, Thorsten; Mersch-Sundermann, Volker

2005-01-01

Consumption of chlorinated drinking water is suspected to be associated with adverse health effects, including mutations and cancer. In the present study, the genotoxic potential of water from Donghu lake, Yangtze river and Hanjiang river in Wuhan, an 8-million metropolis in China, was investigated using HepG2 cells and the alkaline version of the comet assay. It could be shown that all water extracts caused dose-dependent DNA migration in concentrations corresponding to dried extracts of 0.167-167 ml chlorinated drinking water per ml medium. To explore whether the intracellular redox status is regulated by chlorinated drinking water, we determined lipid peroxidation (LPO) and depletion of reduced glutathione (GSH). The malondialdehyde (thiobarbituric acid (TBA)-reactive aldehydes) concentration increased after chlorinated drinking water treatment of HepG2 cells in a dose-dependent manner, the GSH content decreased. The activity of lactate dehydrogenase (LDH) increased in chlorinated drinking water treated HepG2 cells indicating cytotoxicity. In accordance with former studies which dealt with in vivo and in vitro micronucleus induction the present study shows that chlorinated drinking water from polluted raw water may entail genetic risks.

Life history and status of shortnose sturgeon (Acipenser brevirostrum) in the Potomac River

USGS Publications Warehouse

Kieffer, Micah

2009-01-01

We collected the first life history information on shortnose sturgeon (Acipenser brevirostrum) in any of the rivers to Chesapeake Bay, the geographic center of the species range. In the Potomac River, two telemetry-tagged adult females used 124 km of river: a saltwater/freshwater reach at river km (rkm) 63-141 was the foraging-wintering concentration area, and one female migrated to spawn at rkm 187 in Washington, DC. The spawning migration explained the life history context of an adult captured 122 years ago in Washington, DC, supporting the idea that a natal population once lived in the river. Repeated homing migrations to foraging and wintering areas suggested the adults were residents, not transient coastal migrants. All habitats that adults need to complete life history are present in the river. The Potomac River shortnose sturgeon offers a rare opportunity to learn about the natural rebuilding of a sturgeon population.

76 FR 27661 - Notice of Filing of Plats of Survey; Montana

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-12

... sections 7 and 8, the adjusted original meanders of the former left bank of the Missouri River, downstream, through section 18, the meanders of the 2002-2005 left bank of the Missouri River, downstream, through section 18, the limits of erosion, downstream, through section 18, and a certain division of accretion...

Near Earth Current Meander (Necm) Model of Substorms

NASA Astrophysics Data System (ADS)

Heikkila, W. J.; Chen, T.; Liu, Z. X.; Pu, Z. Y.; Pellinen, R. J.; Pulkkinen, T. I.

2001-01-01

We propose that the appropriate instability to trigger a substorm is a tailward meander (in the equatorial plane) of the strong current filament that develops during the growth phase. From this single assumption follows the entire sequence of events for a substorm. The main particle acceleration mechanism in the plasma sheet is curvature drift with a dawn-dusk electric field, leading to the production of auroral arcs. Eventually the curvature becomes so high that the ions cannot negotiate the sharp turn at the field-reversal region, locally, at a certain time. The particle motion becomes chaotic, causing a local outward meander of the cross-tail current. An induction electric field is produced by Lenz's law, E^ind=-∂A/∂t. An outward meander with B_z>0 will cause E×B flow everywhere out from the disturbance; this reaction is a macroscopic instability which we designate the electromotive instability. The response of the plasma is through charge separation and a scalar potential, E^es=-∇φ. Both types of electric fields have components parallel to B in a realistic magnetic field. For MHD theory to hold the net E_∥ must be small; this usually seems to happen (because MHD often does hold), but not always. Part of the response is the formation of field-aligned currents producing the well-known substorm current diversion. This is a direct result of a strong E_∥^ind (the cause) needed to overcome the mirror force of the current carriers; this enables charge separation to produce an opposing electrostatic field E_∥^es (the effect). Satellite data confirm the reality of a strong E_∥ in the plasma sheet by counter-streaming of electrons and ions, and by the inverse ion time dispersion, up to several 100 keV. The electron precipitation is associated with the westward traveling surge (WTS) and the ion with omega (Ω) bands, respectively. However, with zero curl, E^es cannot modify the emf ɛ=∮E.dl=-dΦ^M/dt of the inductive electric field E^ind (a property of

Effects of Chiloquin Dam on spawning distribution and larval emigration of Lost River, shortnose, and Klamath largescale suckers in the Williamson and Sprague Rivers, Oregon

USGS Publications Warehouse

Martin, Barbara A.; Hewitt, David A.; Ellsworth, Craig M.

2013-01-01

Chiloquin Dam was constructed in 1914 on the Sprague River near the town of Chiloquin, Oregon. The dam was identified as a barrier that potentially inhibited or prevented the upstream spawning migrations and other movements of endangered Lost River (Deltistes luxatusChasmistes brevirostris) suckers, as well as other fish species. In 2002, the Bureau of Reclamation led a working group that examined several alternatives to improve fish passage at Chiloquin Dam. Ultimately it was decided that dam removal was the best alternative and the dam was removed in the summer of 2008. The U.S. Geological Survey conducted a long-term study on the spawning ecology of Lost River, shortnose, and Klamath largescale suckers (Catostomus snyderi) in the Sprague and lower Williamson Rivers from 2004 to 2010. The objective of this study was to evaluate shifts in spawning distribution following the removal of Chiloquin Dam. Radio telemetry was used in conjunction with larval production data and detections of fish tagged with passive integrated transponders (PIT tags) to evaluate whether dam removal resulted in increased utilization of spawning habitat farther upstream in the Sprague River. Increased densities of drifting larvae were observed at a site in the lower Williamson River after the dam was removed, but no substantial changes occurred upstream of the former dam site. Adult spawning migrations primarily were influenced by water temperature and did not change with the removal of the dam. Emigration of larvae consistently occurred about 3-4 weeks after adults migrated into a section of river. Detections of PIT-tagged fish showed increases in the numbers of all three suckers that migrated upstream of the dam site following removal, but the increases for Lost River and shortnose suckers were relatively small compared to the total number of fish that made a spawning migration in a given season. Increases for Klamath largescale suckers were more substantial. Post-dam removal monitoring

The Wavelet ToolKat: A set of tools for the analysis of series through wavelet transforms. Application to the channel curvature and the slope control of three free meandering rivers in the Amazon basin.

NASA Astrophysics Data System (ADS)

Vaudor, Lise; Piegay, Herve; Wawrzyniak, Vincent; Spitoni, Marie

2016-04-01

The form and functioning of a geomorphic system result from processes operating at various spatial and temporal scales. Longitudinal channel characteristics thus exhibit complex patterns which vary according to the scale of study, might be periodic or segmented, and are generally blurred by noise. Describing the intricate, multiscale structure of such signals, and identifying at which scales the patterns are dominant and over which sub-reach, could help determine at which scales they should be investigated, and provide insights into the main controlling factors. Wavelet transforms aim at describing data at multiple scales (either in time or space), and are now exploited in geophysics for the analysis of nonstationary series of data. They provide a consistent, non-arbitrary, and multiscale description of a signal's variations and help explore potential causalities. Nevertheless, their use in fluvial geomorphology, notably to study longitudinal patterns, is hindered by a lack of user-friendly tools to help understand, implement, and interpret them. We have developed a free application, The Wavelet ToolKat, designed to facilitate the use of wavelet transforms on temporal or spatial series. We illustrate its usefulness describing longitudinal channel curvature and slope of three freely meandering rivers in the Amazon basin (the Purus, Juruá and Madre de Dios rivers), using topographic data generated from NASA's Shuttle Radar Topography Mission (SRTM) in 2000. Three types of wavelet transforms are used, with different purposes. Continuous Wavelet Transforms are used to identify in a non-arbitrary way the dominant scales and locations at which channel curvature and slope vary. Cross-wavelet transforms, and wavelet coherence and phase are used to identify scales and locations exhibiting significant channel curvature and slope co-variations. Maximal Overlap Discrete Wavelet Transforms decompose data into their variations at a series of scales and are used to provide

Evaluate Status of Pacific Lamprey in the Clearwater River and Salmon River Drainages, Idaho, 2009 Technical Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cochnauer, Tim; Claire, Christopher

2009-05-07

Pacific lamprey Lampetra tridentata have received little attention in fishery science until recently, even though abundance has declined significantly along with other anadromous fish species in Idaho. Pacific lamprey in Idaho have to navigate over eight lower Snake River and Columbia River hydroelectric facilities for migration downstream as juveniles to the Pacific Ocean and again as adults migrating upstream to their freshwater spawning grounds in Idaho. The number of adult Pacific lamprey annually entering the Snake River basin at Ice Harbor Dam has declined from an average of over 18,000 during 1962-1969 to fewer than 600 during 1998-2006. Based onmore » potential accessible streams and adult escapement over Lower Granite Dam on the lower Snake River, we estimate that no more than 200 Pacific lamprey adult spawners annually utilize the Clearwater River drainage in Idaho for spawning. We utilized electrofishing in 2000-2006 to capture, enumerate, and obtain biological information regarding rearing Pacific lamprey ammocoetes and macropthalmia to determine the distribution and status of the species in the Clearwater River drainage, Idaho. Present distribution in the Clearwater River drainage is limited to the lower sections of the Lochsa and Selway rivers, the Middle Fork Clearwater River, the mainstem Clearwater River, the South Fork Clearwater River, and the lower 7.5 km of the Red River. In 2006, younger age classes were absent from the Red River.« less

Bank Erosion Vulnerability Zonation (BEVZ) -A Proposed Method of Preparing Bank Erosion Zonation and Its Application on the River Haora, Tripura, India

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Shreya; de, Sunil Kumar

2014-05-01

In the present paper an attempt has been made to propose RS-GIS based method for erosion vulnerability zonation for the entire river based on simple techniques that requires very less field investigation. This method consist of 8 parameters, such as, rainfall erosivity, lithological factor, bank slope, meander index, river gradient, soil erosivity, vegetation cover and anthropogenic impact. Meteorological data, GSI maps, LISS III (30m resolution), SRTM DEM (56m resolution) and Google Images have been used to determine rainfall erosivity, lithological factor, bank slope, meander index, river gradient, vegetation cover and anthropogenic impact; Soil map of the NBSSLP, India has been used for assessing Soil Erosivity index. By integrating the individual values of those six parameters (the 1st two parameters are remained constant for this particular study area) a bank erosion vulnerability zonation map of the River Haora, Tripura, India (23°37' - 23°53'N and 91°15'-91°37'E) has been prepared. The values have been compared with the existing BEHI-NBS method of 60 spots and also with field data of 30 cross sections (covering the 60 spots) taken along 51 km stretch of the river in Indian Territory and found that the estimated values are matching with the existing method as well as with field data. The whole stretch has been divided into 5 hazard zones, i.e. Very High, High, Moderate, Low and Very Low Hazard Zones and they are covering 5.66 km, 16.81 km, 40.82km, 29.67 km and 9.04 km respectively. KEY WORDS: Bank erosion, Bank Erosion Hazard Index (BEHI), Near Bank Stress (NBS), Erosivity, Bank Erosion Vulnerability Zonation.

Missouri: St. Louis

Atmospheric Science Data Center

2014-05-15

... side, are highlighted with green vegetation. Meandering rivers in the verdant Ozark Plateau appear to the south and west. This ... data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, VA. Image credit: ... October 15, 2005 - Green vegetation and meandering rivers. project:  MISR category:  gallery ...

Migration of Tundra Swans (Cygnus columbianus) Wintering in Japan Using Satellite Tracking: Identification of the Eastern Palearctic Flyway.

PubMed

Chen, Wenbo; Doko, Tomoko; Fujita, Go; Hijikata, Naoya; Tokita, Ken-Ichi; Uchida, Kiyoshi; Konishi, Kan; Hiraoka, Emiko; Higuchi, Hiroyoshi

2016-02-01

Migration through the Eastern Palearctic (EP) flyway by tundra swans (Cygnus columbianus) has not been thoroughly documented. We satellite-tracked the migration of 16 tundra swans that winter in Japan. The objectives of this study were 1) to show the migration pattern of the EP flyway of tundra swans; 2) to compare this pattern with the migration pattern of whooper swans; and 3) to identify stopover sites that are important for these swans' conservation. Tundra swans were captured at Kutcharo Lake, Hokkaido, in 2009-2012 and satellite-tracked. A new method called the "MATCHED (Migratory Analytical Time Change Easy Detection) method" was developed. Based on median, the spring migration began on 18 April and ended on 27 May. Autumn migration began on 9 September and ended on 2 November. The median duration of the spring and autumn migrations were 48 and 50 days, respectively. The mean duration at one stopover site was 5.5 days and 6.8 days for the spring and autumn migrations, respectively. The number of stopover sites was 3.0 and 2.5 for the spring and autumn migrations, respectively. The mean travel distances for the spring and autumn migrations were 6471 and 6331 km, respectively. Seven migration routes passing Sakhalin, the Amur River, and/or Kamchatka were identified. There were 15, 32, and eight wintering, stopover, and breeding sites, respectively. The migration routes and staging areas of tundra swans partially overlap with those of whooper swans, whose migration patterns have been previously documented. The migration patterns of these two swan species that winter in Japan confirm the importance of the Amur River, Udyl' Lake, Shchastya Bay, Aniva Bay, zaliv Chayvo Lake, zal Piltun Lake, zaliv Baykal Lake, Kolyma River, Buyunda River, Sen-kyuyel' Lake, and northern coastal areas of the Sea of Okhotsk.

Magnitude and frequency analysis on river width widening caused by Typhoon Morakot in the Kaoping River watershed, Taiwan

NASA Astrophysics Data System (ADS)

Yang, S. Y.; Jan, C. D.; Wang, Y. C.

2014-12-01

Active evolving rivers are some of the most dynamic and sensitive parts of landscapes. From geologic and geomorphic perspectives, a stable river channel can adjust its width, depth, and slope to prevent significant aggradation or degradation caused by external triggers, e.g., hydrologic events caused by typhoon storms. In particular, the processes of lateral riverbank erosion play a majorly important role in forming horizontal river geomorphology, dominating incised river widens and meanders. Sediment materials produced and mobilized from riverbanks can also be substantial sediment supplying into river channel networks, affecting watershed sediment yield. In Taiwan, the geological and climatic regimes usually combine to generate severely lateral erosion and/or riverbed deposition along river channels, causing the significant change in river width. In the August of 2009, Typhoon Morakot brought severe rainfall of about 2000 mmin Southern Taiwan during three days at the beginning of Aug. 5, leading to significant changes in geomorphic system. Here we characterized river width widening (including Cishan, Laonong, and Ilao Rivers) in the Kaoping River watershed after Typhoon Morakot disturbance interpreted through a power law. On the basis of a temporal pair (2008 and 2009) of Formosat-II (Formosa satellite II) images analysis, the river channels were digitalized within geographic information system (GIS), and river widths were extracted per 100 m along the rivers, then differentiating the adjustment of river width before and after Typhoon Morkot. The river width adjusted from -83 m (contracting) to 1985 m (widening), with an average of 170 m. The noncumulative frequency-magnitude distribution for river width adjustment caused by Typhoon Morakot in the study area satisfies a power-law relation with a determined coefficient (r2) of 0.95, over the range from 65 m to 2373m in the study area. Moreover, the value of the power-law exponent is equal to -2.09. This pattern

Life history and status of shortnose sturgeon (Acipenser brevirostrum) in the potomac river

USGS Publications Warehouse

Kynard, B.; Breece, M.; Atcheson, M.; Kieffer, M.; Mangold, M.

2009-01-01

We collected the first life history information on shortnose sturgeon (Acipenser brevirostrum) in any of the rivers to Chesapeake Bay, the geographic center of the species range. In the Potomac River, two telemetry-tagged adult females used 124 km of river: A saltwater/freshwater reach at river km (rkm) 63-141 was the foraging-wintering concentration area, and one female migrated to spawn at rkm 187 in Washington, DC. The spawning migration explained the life history context of an adult captured 122 years ago in Washington, DC, supporting the idea that a natal population once lived in the river. Repeated homing migrations to foraging and wintering areas suggested the adults were residents, not transient coastal migrants. All habitats that adults need to complete life history are present in the river. The Potomac River shortnose sturgeon offers a rare opportunity to learn about the natural rebuilding of a sturgeon population. ?? 2009 Blackwell Verlag, Berlin.

Migration strategies of Swan Geese Anser cygnoides from northeast Mongolia

USGS Publications Warehouse

Batbayar, Nyambayar; Takekawa, John Y.; Newman, Scott H.; Prosser, Diann J.; Natsagdorj, Tseveenmyadag; Xiao, Xiangming

2011-01-01

In 2006–2008, 25 Swan Geese Anser cygnoides were marked with solar-powered GPS satellite transmitters in northeast Mongolia to examine the timing and pathways of their migration. Most geese began their autumn migration in August, flying southeast toward a staging area at the Yalu River Estuary on the China-North Korea border. After staging for several weeks, the Swan Geese continued to their wintering grounds at wetlands along the Yangtze River Basin of eastern China in December. Spring migration commenced in late February, and the birds following either a same-route or loop migration to arrive at the breeding grounds in mid April. Swan Geese used a larger number of staging areas for a longer duration when they were north of 42°N latitude; they seemed to avoid staging for extended periods in the highly urbanised areas of eastern China. Further research should examine threats and disturbances to the geese in relation to human population growth and increasing urbanisation.

78 FR 23952 - Notice of Filing of Plats of Survey; North Dakota

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-23

..., and the adjusted original meanders of the former left and right banks of the Little Missouri River... meanders of the present left and right banks of the Little Missouri River through sections 29, 31, and 32.... Steve L. Toth, Acting Chief Cadastral Surveyor, Division of Resources. [FR Doc. 2013-09488 Filed 4-22-13...

Bandwidth enhancement of a dual band planar monopole antenna using meandered microstrip feeding.

PubMed

Ahsan, M R; Islam, M T; Habib Ullah, M; Misran, N

2014-01-01

A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (ε r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the -10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz-1 GHz) and at upper band is 28% (2.25 GHz-2.95 GHz). The measured maximum gains of -1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications.

Effects of Iron Gate Dam discharge and other factors on the survival and migration of juvenile coho salmon in the lower Klamath River, northern California, 2006-09

USGS Publications Warehouse

Beeman, John; Juhnke, Steven; Stutzer, Greg; Wright, Katrina

2012-01-01

Current management of the Klamath River includes prescribed minimum discharges intended partly to increase survival of juvenile coho salmon during their seaward migration in the spring. To determine if fish survival was related to river discharge, we estimated apparent survival and migration rates of yearling coho salmon in the Klamath River downstream of Iron Gate Dam. The primary goals were to determine if discharge at Iron Gate Dam affected coho salmon survival and if results from hatchery fish could be used as a surrogate for the limited supply of wild fish. Fish from hatchery and wild origins that had been surgically implanted with radio transmitters were released into the Klamath River slightly downstream of Iron Gate Dam at river kilometer 309. Tagged fish were used to estimate apparent survival between, and passage rates at, a series of detection sites as far downstream as river kilometer 33. Conclusions were based primarily on data from hatchery fish, because wild fish were only available in 2 of the 4 years of study. Based on an information-theoretic approach, apparent survival of hatchery and wild fish was similar, despite differences in passage rates and timing, and was lowest in the 54 kilometer (km) reach between release and the Scott River. Models representing the hypothesis that a short-term tagging- or handling-related mortality occurred following release were moderately supported by data from wild fish and weakly supported by data from hatchery fish. Estimates of apparent survival of hatchery fish through the 276 km study area ranged from 0.412 (standard error [SE] 0.048) to 0.648 (SE 0.070), depending on the year, and represented an average of 0.790 per 100 km traveled. Estimates of apparent survival of wild fish through the study area were 0.645 (SE 0.058) in 2006 and 0.630 (SE 0.059) in 2009 and were nearly identical to the results from hatchery fish released on the same dates. The data and models examined supported positive effects of water

The Role of Anthropogenic Stratigraphy in River Restoration Projects

NASA Astrophysics Data System (ADS)

Evans, J. E.; Webb, L. D.

2012-12-01

As part of a river restoration project and removal of a low-head dam on the Ottawa River (northwestern Ohio and southeastern Michigan) in 2007, a longer-term project was initiated to assess anthropogenic changes of the Ottawa River fluvial system. A composite stratigraphic section 4.5 m in length was constructed by stratigraphic correlation from three trenches up to 2.5 m in depth and 14 vibracores up to 2.5 m in length, all within a small region (<0.5 km2 in area). At various stratigraphic levels, the cores contain a suite of anthropogenic materials including fragments of bricks and cement blocks, pieces of modern ceramics, fragments of plastic and rubber tires, intact or pieces of glass bottles, and one horizon of displaced railroad ties. Age control for the composite section is provided by 4 14C dates, 6 OSL dates, and one bottle with a date stamp. Two prominent flood horizons are indicated in multiple trenches or cores, and identified as the historic floods of 1913 and 1959. The data show the following major changes in the fluvial system over time: (1) prior to approximately 5 Ka, the river system was transporting mineral-rich sediment and formed meandering point-bar sequences approximately 1.5 m thick; (2) between approximately 5 Ka and 200 YBP, the river system was transporting organic-rich sediment (i.e., blackwater stream) bordered by riparian wetlands accumulating peat (part of the regional "Great Black Swamp" discovered by settlers from eastern North America); (3) between approximately 200 YBP and the early 1960s the river system was transporting mineral-rich sediment (i.e., brownwater stream), probably sourced from extensive land clearance for agriculture, which backfilled and overtopped the previous riparian wetlands and produced an series of thin channel fills interpreted as rapidly shifting avulsional channels; (4) since the early 1960s, sediment supply has exceeded sediment conveyance capacity, leading to vertical aggradation of approximately 1.7 m

Spatial Variability in Decomposition of Organic Carbon Along a Meandering River Floodplain

NASA Astrophysics Data System (ADS)

Sutfin, N. A.; Rowland, J. C.; Tfaily, M. M.; Bingol, A. K.; Washton, N.

2017-12-01

Rivers are an important component of the terrestrial carbon cycle and floodplains can provide significant storage of organic carbon. Quantification of long-term storage, however, requires determination of the residence time of sediment and the decomposition rate of organic carbon in floodplains. We use fourier transform ion cyclotron resonance (FTICR) mass spectrometry to examine the organic carbon compounds present in sediment within three floodplain settings: point bars, cutbanks, and abandoned channels. We define decomposition of organic carbon in floodplain sediment as the ratio between the number of protein versus lignin, which serve as proxies for microbial-derived and terrestrial-derived organic carbon, respectively. Samples were collected at 0-5 cm, 5-15cm, and 15-30 cm depth along four transects that span a longitudinal valley distance of 8 km on the East River near Crested Butte, CO. Although no significant trends in decomposition ratio exist longitudinally between the fours transects, floodplain settings exhibit significant differences. At shallow depths (0-5 cm), there are no significant differences among settings, with the exception of gravel portions of point bars below bankfull flow, where the highest decomposition is present. Conversely, cutbanks contain significantly lower decomposition ratios compared with point bars, gravel bars, and abandoned channels when considering all depth intervals. Pointbars exhibit significantly greater protein vs. lignin at the surface compared to greater depth. Higher decomposition ratios along abandoned channels and point bars suggest that frequent wetting and drying periods, abundant oxygen, and continuous downstream movement and decomposition of organic matter occurs within the channel. Lower decomposition ratios and consistent trends with depth along cutbanks, suggest that these stable surfaces serve as organic carbon reservoirs that could become an increased source of carbon to the channel with increasing bank

Water velocity, turbulence, and migration rate of subyearling fall Chinook salmon in the free-flowing and impounded Snake River

USGS Publications Warehouse

Tiffan, Kenneth F.; Kock, Tobias J.; Haskell, Craig A.; Connor, William P.; Steinhorst, R. Kirk

2009-01-01

We studied the migratory behavior of subyearling fall Chinook salmon Oncorhynchus tshawytscha in free-flowing and impounded reaches of the Snake River to evaluate the hypothesis that velocity and turbulence are the primary causal mechanisms of downstream migration. The hypothesis states that impoundment reduces velocity and turbulence and alters the migratory behavior of juvenile Chinook salmon as a result of their reduced perception of these cues. At a constant flow (m3 /s), both velocity (km/d) and turbulence (the SD of velocity) decreased from riverine to impounded habitat as cross-sectional areas increased. We found evidence for the hypothesis that subyearling Chinook salmon perceive velocity and turbulence cues and respond to these cues by varying their behavior. The percentage of the subyearlings that moved faster than the average current speed decreased as fish made the transition from riverine reaches with high velocities and turbulence to upper reservoir reaches with low velocities and turbulence but increased to riverine levels again as the fish moved further down in the reservoir, where velocity and turbulence remained low. The migration rate (km/d) decreased in accordance with longitudinal reductions in velocity and turbulence, as predicted by the hypothesis. The variation in migration rate was better explained by a repeatedmeasures regression model containing velocity (Akaike’s information criterion ¼ 1,769.0) than a model containing flow (2,232.6). We conclude that subyearling fall Chinook salmon respond to changes in water velocity and turbulence, which work together to affect the migration rate.

Perfection and complexity in the lower Brazos River

NASA Astrophysics Data System (ADS)

Phillips, Jonathan D.

2007-11-01

The "perfect landscape" concept is based on the notion that any specific geomorphic system represents the combined, interacting effects of a set of generally applicable global laws and a set of geographically and historically contingent local controls. Because the joint probability of any specific combination of local and global controls is low, and the local controls are inherently idiosyncratic, the probability of existence of any given landscape is vanishingly small. A perfect landscape approach to geomorphic complexity views landscapes as circumstantial, contingent outcomes of deterministic laws operating in a specific environmental and historical context. Thus, explaining evolution of complex landscapes requires the integration of global and local approaches. Because perfection in this sense is the most important and pervasive form of complexity, the study of geomorphic complexity is not restricted to nonlinear dynamics, self-organization, or any other aspects of complexity theory. Beyond what can be achieved via complexity theory, the details of historical and geographic contexts must be addressed. One way to approach this is via synoptic analyses, where the relevant global laws are applied in specific situational contexts. A study of non-acute tributary junctions in the lower Brazos River, Texas illustrates this strategy. The application of generalizations about tributary junction angles, and of relevant theories, does not explain the unexpectedly high occurrence or the specific instances of barbed or straight junctions in the study area. At least five different causes for the development of straight or obtuse junction angles are evident in the lower Brazos. The dominant mechanism, however, is associated with river bank erosion and lateral channel migration which encroaches on upstream-oriented reaches of meandering tributaries. Because the tributaries are generally strongly incised in response to Holocene incision of the Brazos, the junctions are not

Effect of nucleation on instability of step meandering during step-flow growth on vicinal 3C-SiC (0001) surfaces

NASA Astrophysics Data System (ADS)

Li, Yuan; Chen, Xuejiang; Su, Juan

2017-06-01

A three-dimensional kinetic Monte Carlo (KMC) model has been developed to study the step instability caused by nucleation during the step-flow growth of 3C-SiC. In the model, a lattice mesh was established to fix the position of atoms and bond partners based on the crystal lattice of 3C-SiC. The events considered in the model were adsorption and diffusion of adatoms on the terraces, attachment, detachment and interlayer transport of adatoms at the step edges, and nucleation of adatoms. Then the effects of nucleation on the instability of step meandering and the coalescence of both islands and steps were simulated by the model. The results showed that the instability of step meandering caused by nucleation was affected by the growth temperature. And the effects of nucleation on the instability was also analyzed. Moreover, the surface roughness as a function of time for different temperatures was discussed. Finally, a phase diagram was presented to predict in which conditions the effects of nucleation on step meandering become significant and the three different regimes, the step-flow (SF), 2D nucleation (2DN), and 3D layer by layer (3DLBL) were determined.

Sediment budgeting and restoration planning in a heterogeneous landscape, the Root River watershed, southeastern Minnesota.

NASA Astrophysics Data System (ADS)

Hemmis, J. M.; Souffront, M.; Stout, J. C.; Belmont, P.

2014-12-01

Excessive sedimentation in streams and rivers is one of the top water quality concerns in the U.S. and globally. While sediment is a natural constituent of stream ecosystems, excessive amounts cause high levels of turbidity which can reduce primary and secondary production, reduce nutrient retention, and have negative impacts on fish reproduction and physiology. Fine sediment particles adsorb pollutants such as mercury, metals, polychlorinated biphenyl compounds and bacteria. Key questions remain regarding the origin of excessive sediment as well as the transport pathways of sediment through the landscape and channel network of the 4,300 km2 Root River watershed in southeastern Minnesota. To answer these questions, we are developing a sediment budget to account for inputs, outputs, and changes in sediment storage reservoirs within the system. Because watershed sediment fluxes are determined as the sum of many small changes (erosion and deposition) across a vast area, multiple, redundant techniques are required to adequately constrain all parts of the sediment budget. Specifically, this budget utilizes four years of field research and surveys, an extensive set of sediment fingerprinting data, watershed-wide measurements of channel widening and meander migration, and watershed modeling, all evaluated and extrapolated in a geomorphically sensitive manner. Analyses of sediment deposition within channel cutoffs throughout the watershed help constrain sediment storage. These overlapping methods, reconciled within the hard constraint of direct measurements of water and sediment fluxes, improve the reliability of the budget. The sediment budget highlights important sources and sinks and identifies locations that are likely to be more, or less, sensitive to changes in land and water management to support watershed-wide prioritization of conservation and restoration actions.

Downstream Migration of Masu Salmon Smolt at a Diversion Facility of Dam

NASA Astrophysics Data System (ADS)

Hayashida, K.; Nii, H.; Kasuga, K.; Watanabe, K.

2014-12-01

A diversion facility was installed on the upstream of Pirika Dam in Northern Japan that produced a downstream flow into the fishway, thus allowing the fish to migrate to the sea. On the other hand, if the flow rate in the river was more than 7.00 m 3/s (design flow rate of diversion facility), masu salmon smolt were concerned about accessing the dam reservoir, because the smolt can't migrate to the sea through the diversion facility unfortunately. Therefore, the downstream migration of smolt was investigated around the diversion facility. The PIT tag system and radio transmitters as the biotelemetry were used to determine 1) whether masu salmon smolt were able to migrate downstream through the diversion facility and fishway at Pirika Dam, 2) when the smolt started to migrate downstream, 3) whether the downstream migration of smolt were affected by the flow increase in the river. It was clarified that 88% of the smolt were able to enter the diversion facility, and then 81% of the smolt were able to access the fishway. It was also clarified that smolt downstream migration had two peaks in a day (5:00 and 18:00). During the study period, although the flow rate was in the 2.21 m3/s to 30.44 m3/s range (average 6.70 m3/s), it was revealed that the diversion facility has a satisfactory function for the downstream migration of smolt as presented above. The survey clarified the downstream migration behavior of masu salmon by using two types of biotelemetry equipment. PIT tag and radio transmitter were found to be very effective in tracking the behavior of small fish such as smolt. PIT tags, in particular, require very little operating cost, because once they are inserted in the fish, they do not need human labor for tracking. It is desirable to actively introduce the biotelemetry as tracking equipment when surveying the fish migration in the river.

Impacts of Colville River dynamics on river navigability near Nuiqsut, Alaska: 1955-present

NASA Astrophysics Data System (ADS)

Whitley, M. A.; Panda, S. K.; Prakash, A.; Brinkman, T. J.

2016-12-01

Climate-driven changes in river systems are challenging access to ecosystem services such as access to traditional hunting grounds and other subsistence food sources on the North Slope of Alaska. This work studies the dynamics of the Colville River and assesses the impacts on traditional harvest practices and subsistence travel of the Native community of Nuiqsut. Recent reports from Nuiqsut residents indicate accelerated changes in the environment, limiting river travel and their ability to harvest subsistence food. This study explores how channel migration, gravel bars, and bank erosion have evolved since the 1950s, and their impact on water depth and navigability. In an area of ice-rich permafrost, warmer summer temperatures exacerbate lateral bank erosion, resulting in river siltation. The study focuses on selected key areas south of Nuiqsut that have shown significant change in river geomorphology. Since 1955, some areas proximate to ice wedge exposures show channel migration in excess of 1 km. Panchromatic aerial photography acquired by US Geological Surveys in the mid 1950s, color infrared aerial photography from 1979 and 1982 acquired by the Alaska High Altitude Photography (AHAP) mission, and high resolution satellite images from Digital Globe, Inc. were used in this study. We mapped water, vegetation, and gravel/non-vegetated classes to identify risk areas for river navigability. River bathymetry was also mapped using a multispectral ratio-based water depth retrieval algorithm to identify problem sites for boat travel. Remote sensing products and analyses were validated with field data for mapping risk areas along the river. This study has the potential to be implemented on a larger scale for predictive mapping to aid river navigation. Findings from this study will provide insight whether recent changes are anomalies, or if they are part of a directional trend that will require local adaptation.

Estimating Error in SRTM Derived Planform of a River in Data-poor Region and Subsequent Impact on Inundation Modeling

NASA Astrophysics Data System (ADS)

Bhuyian, M. N. M.; Kalyanapu, A. J.

2017-12-01

Accurate representation of river planform is critical for hydrodynamic modeling. Digital elevation models (DEM) often falls short in accurately representing river planform because they show the ground as it was during data acquisition. But, water bodies (i.e. rivers) change their size and shape over time. River planforms are more dynamic in undisturbed riverine systems (mostly located in data-poor regions) where remote sensing is the most convenient source of data. For many of such regions, Shuttle Radar Topographic Mission (SRTM) is the best available source of DEM. Therefore, the objective of this study is to estimate the error in SRTM derived planform of a river in a data-poor region and estimate the subsequent impact on inundation modeling. Analysis of Landsat image, SRTM DEM and remotely sensed soil data was used to classify the planform activity in an 185 km stretch of the Kushiyara River in Bangladesh. In last 15 years, the river eroded about 4.65 square km and deposited 7.55 square km area. Therefore, current (the year 2017) river planform is significantly different than the SRTM water body data which represents the time of SRTM data acquisition (the year 2000). The rate of planform shifting significantly increased as the river traveled to downstream. Therefore, the study area was divided into three reaches (R1, R2, and R3) from upstream to downstream. Channel slope and meandering ratio changed from 2x10-7 and 1.64 in R1 to 1x10-4 and 1.45 in R3. However, more than 60% erosion-deposition occurred in R3 where a high percentage of Fluvisols (98%) and coarse particles (21%) were present in the vicinity of the river. It indicates errors in SRTM water body data (due to planform shifting) could be correlated with the physical properties (i.e. slope, soil type, meandering ratio etc.) of the riverine system. The correlations would help in zoning activity of a riverine system and determine a timeline to update DEM for a given region. Additionally, to estimate the

Bandwidth Enhancement of a Dual Band Planar Monopole Antenna Using Meandered Microstrip Feeding

PubMed Central

Ahsan, M. R.; Islam, M. T.; Habib Ullah, M.; Misran, N.

2014-01-01

A meandered-microstrip fed circular shaped monopole antenna loaded with vertical slots on a high dielectric material substrate (ε r = 15) is proposed in this paper. The performance criteria of the proposed antenna have been experimentally verified by fabricating a printed prototype. The experimental results show that the proposed antenna has achieved wider bandwidth with satisfactory gain by introducing meandered-microstrip feeding in assistant of partial ground plane. It is observed that, the −10 dB impedance bandwidth of the proposed antenna at lower band is 44.4% (600 MHz–1 GHz) and at upper band is 28% (2.25 GHz–2.95 GHz). The measured maximum gains of −1.18 dBi and 4.87 dBi with maximum radiation efficiencies have been observed at lower band and upper band, respectively. The antenna configuration and parametric study have been carried out with the help of commercially available computer-aided EM simulator, and a good accordance is perceived in between the simulated and measured results. The analysis of performance criteria and almost consistent radiation pattern make the proposed antenna a suitable candidate for UHF RFID, WiMAX, and WLAN applications. PMID:24723832

Polychlorinated Biphenyls in suspended-sediment samples from outfalls to Meandering Road Creek at Air Force Plant 4, Fort Worth, Texas, 2003-08

USGS Publications Warehouse

Braun, Christopher L.; Wilson, Jennifer T.

2010-01-01

Meandering Road Creek is an intermittent stream and tributary to Lake Worth, a reservoir on the West Fork Trinity River on the western edge of Fort Worth, Texas. U.S. Air Force Plant 4 (AFP4) is on the eastern shore of Woods Inlet, an arm of Lake Worth. Meandering Road Creek gains inflow from several stormwater outfalls as it flows across AFP4. Several studies have characterized polychlorinated biphenyls (PCBs) in the water and sediments of Lake Worth and Meandering Road Creek; sources of PCBs are believed to originate primarily from AFP4. Two previous U.S. Geological Survey (USGS) reports documented elevated PCB concentrations in surficial sediment samples from Woods Inlet relative to concentrations in surficial sediment samples from other parts of Lake Worth. The second of these two previous reports also identified some of the sources of PCBs to Lake Worth. These reports were followed by a third USGS report that documented the extent of PCB contamination in Meandering Road Creek and Woods Inlet and identified runoff from outfalls 4 and 5 at AFP4 as prominent sources of these PCBs. This report describes the results of a fourth study by the USGS, in cooperation with the Lockheed Martin Corporation, to investigate PCBs in suspended-sediment samples in storm runoff from outfalls 4 and 5 at AFP4 following the implementation of engineering controls designed to potentially alleviate PCB contamination in the drainage areas of these outfalls. Suspended-sediment samples collected from outfalls 4 and 5 during storms on March 2 and November 10, 2008, were analyzed for selected PCBs. Sums of concentrations of 18 reported PCB congeners (Sigma PCBc) in suspended-sediment samples collected before and after implementation of engineering controls are compared. At both outfalls, the Sigma PCBc before engineering controls was higher than the Sigma PCBc after engineering controls. The Sigma PCBc in suspended-sediment samples collected at AFP4 before and after implementation of

Anastomosing rivers: a review of their classification, origin and sedimentary products

NASA Astrophysics Data System (ADS)

Makaske, Bart

2001-04-01

Anastomosing rivers constitute an important category of multi-channel rivers on alluvial plains. Most often they seem to form under relatively low-energetic conditions near a (local) base level. It appears to be impossible to define anastomosing rivers unambiguously on the basis of channel planform only. Therefore, the following definition, which couples floodplain geomorphology and channel pattern, is proposed in this paper: an anastomosing river is composed of two or more interconnected channels that enclose floodbasins. This definition explicitly excludes the phenomenon of channel splitting by convex-up bar-like forms that characterize braided channels. In present definitions of anastomosing rivers, lateral stability of channels is commonly coupled with their multi-channel character. Here, it is suggested that these two properties be uncoupled. At the scale of channel belts, the terms 'straight', 'meandering' and 'braided' apply, whereas at a larger scale, a river can be called anastomosing if it meets the definition given above. This means that, straight, meandering and braided channels may all be part of an anastomosing river system. Straight channels are defined by a sinuosity index; i.e., the ratio of the distance along the channel and the distance along the channel-belt axis is less than 1.3. They are the type of channel that most commonly occurs in combination with anastomosis. The occurrence of straight channels is favoured by low stream power, basically a product of discharge and gradient, and erosion-resistant banks. Anastomosing rivers are usually formed by avulsions, i.e., flow diversions that cause the formation of new channels on the floodplain. As a product of avulsion, anastomosing rivers essentially form in two ways: (1) by formation of bypasses, while bypassed older channel-belt segments remain active for some period; and (2) by splitting of the diverted avulsive flow, leading to contemporaneous scour of multiple channels on the floodplain. Both

Migration of Sakhalin taimen (Parahucho perryi): Evidence of freshwater resident life history types

USGS Publications Warehouse

Zimmerman, C.E.; Rand, P.S.; Fukushima, M.; Zolotukhin, S.F.

2012-01-01

Sakhalin taimen (Parahucho perryi) range from the Russian Far East mainland along the Sea of Japan coast, and Sakhalin, Kuril, and Hokkaido Islands and are considered to primarily be an anadromous species. We used otolith strontium-to-calcium ratios (Sr/Ca) to determine the chronology of migration between freshwater and saltwater and identify migratory contingents of taimen collected from the Koppi River, Russia. In addition, we examined taimen from the Sarufutsu River, Japan and Tumnin River, Russia that were captured in marine waters. Transects of otolith Sr/Ca for the Sarufutsu River fish were consistent with patterns observed in anadromous salmonids. Two fish from the Tumnin River appeared to be recent migrants to saltwater and one fish was characterized by an otolith Sr/Ca transect consistent with marine migration. Using these transects as benchmarks, all Koppi River taimen were classified as freshwater residents. These findings suggest more work is needed to assess life history variability among locations and the role of freshwater productivity in controlling migratory behavior in taimen. ?? 2011 Springer Science+Business Media B.V. (outside the USA).

St. Louis River fish migrations: Gains and losses of ecosystem ...

EPA Pesticide Factsheets

The Twin Ports fishery has undergone change from a migratory fish-based fishery to a Lake Superior-based fishery, and is now returning to a diverse fishery that includes fish of both life histories. These changes reflect past disturbances to the Great Lakes ecosystem as well as recent water quality improvement and efforts to restore habitat in the St. Louis River. Migratory fishes are an important ecosystem service for the St. Louis River, and improvements to the ecosystem quality within the St. Louis River Area of Concern has benefited migratory fishes. The coastal wetlands within the lower river provide direct support to a variety of high-value, recreationally-important fish species, including walleye, northern pike, and bass. Moreover, these wetlands serve as nursery habitat for a broader suite of high-value, commercially-important species. Restoration has likely improved the value of these coastal wetlands because low-value rough species tend to be more prevalent in degraded coastal wetlands, whereas high-value commercial and game fishes are more prevalent in high-quality coastal wetlands. There have been losses in ecosystem services, as well. Owing to legacy contamination of mercury and PCBs, migratory fishes in the St. Louis River have sufficiently high contaminant burdens to warrant consumption advisories, and recent movement research demonstrates that there is a positive relationship between increased use of St. Louis River habitat (versus Lake Superior)

Experimental Study on the Wake Meandering Within a Scale Model Wind Farm Subject to a Wind-Tunnel Flow Simulating an Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

Coudou, Nicolas; Buckingham, Sophia; Bricteux, Laurent; van Beeck, Jeroen

2017-12-01

The phenomenon of meandering of the wind-turbine wake comprises the motion of the wake as a whole in both horizontal and vertical directions as it is advected downstream. The oscillatory motion of the wake is a crucial factor in wind farms, because it increases the fatigue loads, and, in particular, the yaw loads on downstream turbines. To address this phenomenon, experimental investigations are carried out in a wind-tunnel flow simulating an atmospheric boundary layer with the Coriolis effect neglected. A 3 × 3 scaled wind farm composed of three-bladed rotating wind-turbine models is subject to a neutral boundary layer over a slightly-rough surface, i.e. corresponding to offshore conditions. Particle-image-velocimetry measurements are performed in a horizontal plane at hub height in the wakes of the three wind turbines occupying the wind-farm centreline. These measurements allow determination of the wake centrelines, with spectral analysis indicating the characteristic wavelength of the wake-meandering phenomenon. In addition, measurements with hot-wire anemometry are performed along a vertical line in the wakes of the same wind turbines, with both techniques revealing the presence of wake meandering behind all three turbines. The spectral analysis performed with the spatial and temporal signals obtained from these two measurement techniques indicates a Strouhal number of ≈ 0.20 - 0.22 based on the characteristic wake-meandering frequency, the rotor diameter and the flow speed at hub height.

Experimental Study on the Wake Meandering Within a Scale Model Wind Farm Subject to a Wind-Tunnel Flow Simulating an Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

Coudou, Nicolas; Buckingham, Sophia; Bricteux, Laurent; van Beeck, Jeroen

2018-04-01

The phenomenon of meandering of the wind-turbine wake comprises the motion of the wake as a whole in both horizontal and vertical directions as it is advected downstream. The oscillatory motion of the wake is a crucial factor in wind farms, because it increases the fatigue loads, and, in particular, the yaw loads on downstream turbines. To address this phenomenon, experimental investigations are carried out in a wind-tunnel flow simulating an atmospheric boundary layer with the Coriolis effect neglected. A 3 × 3 scaled wind farm composed of three-bladed rotating wind-turbine models is subject to a neutral boundary layer over a slightly-rough surface, i.e. corresponding to offshore conditions. Particle-image-velocimetry measurements are performed in a horizontal plane at hub height in the wakes of the three wind turbines occupying the wind-farm centreline. These measurements allow determination of the wake centrelines, with spectral analysis indicating the characteristic wavelength of the wake-meandering phenomenon. In addition, measurements with hot-wire anemometry are performed along a vertical line in the wakes of the same wind turbines, with both techniques revealing the presence of wake meandering behind all three turbines. The spectral analysis performed with the spatial and temporal signals obtained from these two measurement techniques indicates a Strouhal number of ≈ 0.20 - 0.22 based on the characteristic wake-meandering frequency, the rotor diameter and the flow speed at hub height.

Efficiency of two-way weirs and prepositioned electrofishing for sampling potamodromous fish migrations

USGS Publications Warehouse

Favrot, Scott D.; Kwak, Thomas J.

2016-01-01

Potamodromy (i.e., migration entirely in freshwater) is a common life history strategy of North American lotic fishes, and efficient sampling methods for potamodromous fishes are needed to formulate conservation and management decisions. Many potamodromous fishes inhabit medium-sized rivers and are mobile during spawning migrations, which complicates sampling with conventional gears (e.g., nets and electrofishing). We compared the efficiency of a passive migration technique (resistance board weirs) and an active technique (prepositioned areal electrofishers; [PAEs]) for sampling migrating potamodromous fishes in Valley River, a southern Appalachian Mountain river, from March through July 2006 and 2007. A total of 35 fish species from 10 families were collected, 32 species by PAE and 19 species by weir. Species richness and diversity were higher for PAE catch, and species dominance (i.e., proportion of assemblage composed of the three most abundant species) was higher for weir catch. Prepositioned areal electrofisher catch by number was considerably higher than weir catch, but biomass was lower for PAE catch. Weir catch decreased following the spawning migration, while PAEs continued to collect fish. Sampling bias associated with water velocity was detected for PAEs, but not weirs, and neither gear demonstrated depth bias in wadeable reaches. Mean fish mortality from PAEs was five times greater than that from weirs. Catch efficiency and composition comparisons indicated that weirs were effective at documenting migration chronology, sampling nocturnal migration, and yielding samples unbiased by water velocity or habitat, with low mortality. Prepositioned areal electrofishers are an appropriate sampling technique for seasonal fish occupancy objectives, while weirs are more suitable for quantitatively describing spawning migrations. Our comparative results may guide fisheries scientists in selecting an appropriate sampling gear and regime for research, monitoring

Rivers as Political Boundaries: Peru and its Dynamic Borders

NASA Astrophysics Data System (ADS)

Abad, J. D.; Escobar, C.; Garcia, A. M. P.; Ortals, C.; Frias, C. E.; Vizcarra, J.

2014-12-01

Rivers, although inherently dynamic, have been chosen as political boundaries since the beginning of colonization for several reasons. Such divisions were chosen namely for their defensive capabilities and military benefits, and because they were often the first features mapped out by explorers. Furthermore, rivers were indisputable boundaries that did not require boundary pillars or people to guard them. However, it is important to understand the complexities of a river as a boundary. All rivers inevitably change over time through processes such as accretion, deposition, cut-off, or avulsion, rendering a political boundary subject to dispute. Depending upon the flow, size, and surrounding land, a river will migrate differently than others. As these natural features migrate one country loses land while another gains land leading to tension between legal rigidity and fluid dynamism. This in turn can manifest in social disruption due to cultural differences, political upheaval, or conflict risk as a result of scarce water resources. The purpose of this research is to assess the temporal and spatial variability of the political boundaries of Peru that follow rivers. Peru shares borders with Colombia, Brazil, Bolivia, Chile, and Ecuador. A large part of its northern border with Colombia follows the Putumayo River and later the Amazon River. Part of its eastern border with Brazil follows the Yavari River and later the Yaquirana River. These rivers are natural features used as political boundaries yet they differ in how each migrates. By means of a spatial and temporal analysis of satellite images it was possible to obtain erosion and deposition areas for the Putumayo River, the portion of the Amazon River that is part of the Peruvian boundary, the Yavari River, and the Yaquirana River. The erosion and deposition areas were related to land distribution among Peru, Colombia, and Brazil. By examining the Digital Elevation Model one can see how the altitude of the

Elwha River dam removal-Rebirth of a river

USGS Publications Warehouse

Duda, Jeffrey J.; Warrick, Jonathan A.; Magirl, Christopher S.

2011-01-01

After years of planning for the largest project of its kind, the Department of the Interior will begin removal of two dams on the Elwha River, Washington, in September 2011. For nearly 100 years, the Elwha and Glines Canyon Dams have disrupted natural processes, trapping sediment in the reservoirs and blocking fish migrations, which changed the ecology of the river downstream of the dams. All five Pacific salmon species and steelhead-historically present in large numbers-are locally extirpated or persist in critically low numbers. Upstream of the dams, more than 145 kilometers of pristine habitat, protected inside Olympic National Park, awaits the return of salmon populations. As the dams are removed during a 2-3 year project, some of the 19 million cubic meters of entrapped sediment will be carried downstream by the river in the largest controlled release of sediment into a river and marine waters in history. Understanding the changes to the river and coastal habitats, the fate of sediments, and the salmon recolonization of the Elwha River wilderness will provide useful information for society as future dam removals are considered.

Evaluation of CAESAR-Lisflood as a tool for modelling river channel change and floodplain sediment residence times.

NASA Astrophysics Data System (ADS)

Feeney, Christopher; Smith, Hugh; Chiverrell, Richard; Hooke, Janet; Cooper, James

2017-04-01

Sediment residence time represents the duration of particle storage, from initial deposition to remobilisation, within reservoirs such as floodplains. Residence time influences rates of downstream redistribution of sediment and associated contaminants and is a useful indicator of landform stability and hence, preservation potential of alluvial archives of environmental change. River channel change controls residence times, reworking sediments via lateral migration, avulsion and incision through floodplain deposits. As reworking progresses, the floodplain age distribution is 'updated', reflecting the time since 'older' sediments were removed and replaced with 'younger' ones. The relationship between ages and the spatial extents they occupy can be used to estimate the average floodplain sediment residence times. While dating techniques, historic maps and remote sensing can reconstruct age distributions from historic reworking, modelling provides advantages, including: i) capturing detailed river channel changes and resulting floodplain ages over longer timescales and higher resolutions than from historic mapping, and ii) control over inputs to simulate hypothetical scenarios to investigate the effects of different environmental drivers on residence times. CAESAR-Lisflood is a landform evolution model capable of simulating variable channel width, divergent flow, and both braided and meandering planforms. However, the model's ability to accurately simulate channel changes requires evaluation if it is to be useful for quantitative evaluation of floodplain sediment residence times. This study aims to simulate recent historic river channel changes along ten 1 km reaches in northern England. Simulation periods were defined by available overlapping historic map and mean daily flow datasets, ranging 27-39 years. LiDAR-derived 2 m DEMs were modified to smooth out present-day channels and burn in historic channel locations. To reduce run times, DEMs were resampled to coarser

Juvenile salmonid migratory behavior at the mouth of the Columbia River and within the plume

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMichael, Geoffrey A.; O'Toole, Amanda C.; Harnish, Ryan A.

A total of 8,159 acoustic-tagged salmonid smolts were detected at the mouth of the Columbia River. Of the fish detected at the mouth, 14% of yearling Chinook salmon, 9% of steelhead, and 22% of subyearling Chinook salmon were detected on a sparse array deployed in the Columbia River plume. Chinook salmon smolts decreased travel rate as they left the river and entered the plume, while steelhead increased travel rate. Chinook salmon also spent more time in the transitional area between the river mouth and plume as compared to steelhead. In early spring, yearling Chinook salmon and steelhead predominately migrated pastmore » the plume array towards the edge of the shelf and to the south. Later in the season, yearling Chinook salmon and steelhead smolts tended to migrate out of the river mouth in a northerly direction. Subyearling Chinook salmon migrated predominately past the portion of the plume array to the north of the river mouth.« less

Examining the spatial and temporal variation of groundwater inflows to a valley-to-floodplain river using 222Rn, geochemistry and river discharge: the Ovens River, southeast Australia

NASA Astrophysics Data System (ADS)

Yu, M. C. L.; Cartwright, I.; Braden, J. L.; de Bree, S. T.

2013-12-01

Radon (222Rn) and major ion geochemistry were used to define and quantify the catchment-scale groundwater-surface water interactions along the Ovens River in the southeast Murray-Darling Basin, Victoria, Australia, between September 2009 and October 2011. The Ovens River is characterized by the transition from a single channel within a mountain valley in the upper catchment to a multi-channel meandering river on flat alluvial plains in the lower catchment. Overall, the Ovens River is dominated by gaining reaches, receiving groundwater from both alluvial and basement aquifers. The distribution of gaining and losing reaches is governed by catchment morphology and lithology. In the upper catchment, rapid groundwater recharge through the permeable aquifers increases the water table. The rising water table, referred to as hydraulic loading, increases the hydraulic head gradient toward the river and hence causes high baseflow to the river during wet (high flow) periods. In the lower catchment, lower rainfall and finer-gained sediments reduce the magnitude and variability of hydraulic gradient between the aquifer and the river, producing lower but more constant groundwater inflows. The water table in the lower reaches has a shallow gradient, and small changes in river height or groundwater level can result in fluctuating gaining and losing behaviour. The middle catchment represents a transition in river-aquifer interactions from the upper to the lower catchment. High baseflow in some parts of the middle and lower catchments is caused by groundwater flowing over basement highs. Mass balance calculations based on 222Rn activities indicate that groundwater inflows are 2 to 17% of total flow with higher inflows occurring during high flow periods. In comparison to 222Rn activities, estimates of groundwater inflows from Cl concentrations are higher by up to 2000% in the upper and middle catchment but lower by 50 to 100% in the lower catchment. The high baseflow estimates using

Influence of multiple dam passage on survival of juvenile Chinook salmon in the Columbia River estuary and coastal ocean

PubMed Central

Rechisky, Erin L.; Welch, David W.; Porter, Aswea D.; Jacobs-Scott, Melinda C.; Winchell, Paul M.

2013-01-01

Multiple dam passage during seaward migration is thought to reduce the subsequent survival of Snake River Chinook salmon. This hypothesis developed because juvenile Chinook salmon from the Snake River, the Columbia River’s largest tributary, migrate >700 km through eight hydropower dams and have lower adult return rates than downstream populations that migrate through only 3 or 4 dams. Using a large-scale telemetry array, we tested whether survival of hatchery-reared juvenile Snake River spring Chinook salmon is reduced in the estuary and coastal ocean relative to a downstream, hatchery-reared population from the Yakima River. During the initial 750-km, 1-mo-long migration through the estuary and coastal ocean, we found no evidence of differential survival; therefore, poorer adult returns of Snake River Chinook may develop far from the Columbia River. Thus, hydrosystem mitigation efforts may be ineffective if differential mortality rates develop in the North Pacific Ocean for reasons unrelated to dam passage. PMID:23576733

Assessment of floodplain vulnerability during extreme Mississippi River flood 2011

USGS Publications Warehouse

Goodwell, Allison E.; Zhu, Zhenduo; Dutta, Debsunder; Greenberg, Jonathan A.; Kumar, Praveen; Garcia, Marcelo H.; Rhoads, Bruce L.; Holmes, Robert R.; Parker, Gary; Berretta, David P.; Jacobson, Robert B.

2014-01-01

Regional change in the variability and magnitude of flooding could be a major consequence of future global climate change. Extreme floods have the capacity to rapidly transform landscapes and expose landscape vulnerabilities through highly variable spatial patterns of inundation, erosion, and deposition. We use the historic activation of the Birds Point-New Madrid Floodway during the Mississippi and Ohio River Flooding of 2011 as a scientifically unique stress experiment to analyze indicators of floodplain vulnerability. We use pre- and postflood airborne Light Detection and Ranging data sets to locate erosional and depositional hotspots over the 540 km2 agricultural Floodway. While riparian vegetation between the river and the main levee breach likely prevented widespread deposition, localized scour and deposition occurred near the levee breaches. Eroded gullies nearly 1 km in length were observed at a low ridge of a relict meander scar of the Mississippi River. Our flow modeling and spatial mapping analysis attributes this vulnerability to a combination of erodible soils, flow acceleration associated with legacy fluvial landforms, and a lack of woody vegetation to anchor soil and enhance flow resistance. Results from this study could guide future mitigation and adaptation measures in cases of extreme flooding.

Assessment of floodplain vulnerability during extreme Mississippi River flood 2011.

PubMed

Goodwell, Allison E; Zhu, Zhenduo; Dutta, Debsunder; Greenberg, Jonathan A; Kumar, Praveen; Garcia, Marcelo H; Rhoads, Bruce L; Holmes, Robert R; Parker, Gary; Berretta, David P; Jacobson, Robert B

2014-01-01

Regional change in the variability and magnitude of flooding could be a major consequence of future global climate change. Extreme floods have the capacity to rapidly transform landscapes and expose landscape vulnerabilities through highly variable spatial patterns of inundation, erosion, and deposition. We use the historic activation of the Birds Point-New Madrid Floodway during the Mississippi and Ohio River Flooding of 2011 as a scientifically unique stress experiment to analyze indicators of floodplain vulnerability. We use pre- and postflood airborne Light Detection and Ranging data sets to locate erosional and depositional hotspots over the 540 km(2) agricultural Floodway. While riparian vegetation between the river and the main levee breach likely prevented widespread deposition, localized scour and deposition occurred near the levee breaches. Eroded gullies nearly 1 km in length were observed at a low ridge of a relict meander scar of the Mississippi River. Our flow modeling and spatial mapping analysis attributes this vulnerability to a combination of erodible soils, flow acceleration associated with legacy fluvial landforms, and a lack of woody vegetation to anchor soil and enhance flow resistance. Results from this study could guide future mitigation and adaptation measures in cases of extreme flooding.

Differences in Ichthyophonus prevalence and infection severity between upper Yukon River and Tanana River chinook salmon, Oncorhynchus tshawytscha (Walbaum), stocks

USGS Publications Warehouse

Kocan, R.; Hershberger, P.

2006-01-01

Two genetically distinct populations of chinook salmon, Oncorhynchus tshawytscha (Walbaum), were simultaneously sampled at the confluence of the Yukon and Tanana rivers in 2003. Upper Yukon-Canadian fish had significantly higher infection prevalence as well as more severe infections (higher parasite density in heart tissue) than the lower Yukon-Tanana River fish. Both populations had migrated the same distance from the mouth of the Yukon River at the time of sampling but had significantly different distances remaining to swim before reaching their respective spawning grounds. Multiple working hypotheses are proposed to explain the differences between the two stocks: (1) the two genetically distinct populations have different inherent resistance to infection, (2) genetically influenced differences in feeding behaviour resulted in temporal and/or spatial differences in exposure, (3) physiological differences resulting from different degrees of sexual maturity influenced the course of disease, and (4) the most severely infected Tanana River fish either died en route or fatigued and were unable to complete their migration to the Tanana River, thus leaving a population of apparently healthier fish. ?? 2006 Blackwell Publishing Ltd.

Migration trends of Sockeye Salmon at the northern edge of their distribution

USGS Publications Warehouse

Carey, Michael P.; Zimmerman, Christian E.; Keith, Kevin D.; Schelske, Merlyn; Lean, Charles; Douglas, David C.

2017-01-01

Climate change is affecting arctic and subarctic ecosystems, and anadromous fish such as Pacific salmon Oncorhynchus spp. are particularly susceptible due to the physiological challenge of spawning migrations. Predicting how migratory timing will change under Arctic warming scenarios requires an understanding of how environmental factors drive salmon migrations. Multiple mechanisms exist by which environmental conditions may influence migrating salmon, including altered migration cues from the ocean and natal river. We explored relationships between interannual variability and annual migration timing (2003–2014) of Sockeye Salmon O. nerka in a subarctic watershed with environmental conditions at broad, intermediate, and local spatial scales. Low numbers of Sockeye Salmon have returned to this high-latitude watershed in recent years, and run size has been a dominant influence on the migration duration and the midpoint date of the run. The duration of the migration upriver varied by as much as 25 d across years, and shorter run durations were associated with smaller run sizes. The duration of the migration was also extended with warmer sea surface temperatures in the staging area and lower values of the North Pacific Index. The midpoint date of the total run was earlier when the run size was larger, whereas the midpoint date was delayed during years in which river temperatures warmed earlier in the season. Documenting factors related to the migration of Sockeye Salmon near the northern limit of their range provides insights into the determinants of salmon migrations and suggests processes that could be important for determining future changes in arctic and subarctic ecosystems.

New Insights on Water Buffalo Genomic Diversity and Post-Domestication Migration Routes From Medium Density SNP Chip Data.

PubMed

Colli, Licia; Milanesi, Marco; Vajana, Elia; Iamartino, Daniela; Bomba, Lorenzo; Puglisi, Francesco; Del Corvo, Marcello; Nicolazzi, Ezequiel L; Ahmed, Sahar S E; Herrera, Jesus R V; Cruz, Libertado; Zhang, Shujun; Liang, Aixin; Hua, Guohua; Yang, Liguo; Hao, Xingjie; Zuo, Fuyuan; Lai, Song-Jia; Wang, Shuilian; Liu, Ruyu; Gong, Yundeng; Mokhber, Mahdi; Mao, Yongjiang; Guan, Feng; Vlaic, Augustin; Vlaic, Bogdan; Ramunno, Luigi; Cosenza, Gianfranco; Ahmad, Ali; Soysal, Ihsan; Ünal, Emel Ö; Ketudat-Cairns, Mariena; Garcia, José F; Utsunomiya, Yuri T; Baruselli, Pietro S; Amaral, Maria E J; Parnpai, Rangsun; Drummond, Marcela G; Galbusera, Peter; Burton, James; Hoal, Eileen; Yusnizar, Yulnawati; Sumantri, Cece; Moioli, Bianca; Valentini, Alessio; Stella, Alessandra; Williams, John L; Ajmone-Marsan, Paolo

2018-01-01

The domestic water buffalo is native to the Asian continent but through historical migrations and recent importations, nowadays has a worldwide distribution. The two types of water buffalo, i.e., river and swamp, display distinct morphological and behavioral traits, different karyotypes and also have different purposes and geographical distributions. River buffaloes from Pakistan, Iran, Turkey, Egypt, Romania, Bulgaria, Italy, Mozambique, Brazil and Colombia, and swamp buffaloes from China, Thailand, Philippines, Indonesia and Brazil were genotyped with a species-specific medium-density 90K SNP panel. We estimated the levels of molecular diversity and described population structure, which revealed historical relationships between populations and migration events. Three distinct gene pools were identified in pure river as well as in pure swamp buffalo populations. Genomic admixture was seen in the Philippines and in Brazil, resulting from importations of animals for breed improvement. Our results were largely consistent with previous archeological, historical and molecular-based evidence for two independent domestication events for river- and swamp-type buffaloes, which occurred in the Indo-Pakistani region and close to the China/Indochina border, respectively. Based on a geographical analysis of the distribution of diversity, our evidence also indicated that the water buffalo spread out of the domestication centers followed two major divergent migration directions: river buffaloes migrated west from the Indian sub-continent while swamp buffaloes migrated from northern Indochina via an east-south-eastern route. These data suggest that the current distribution of water buffalo diversity has been shaped by the combined effects of multiple migration events occurred at different stages of the post-domestication history of the species.