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Sample records for juniata river channel

  1. Synthesizing Evidence to Assess the Causes of Smallmouth Bass Declines at the Susquehanna and Juniata Rivers, Pennsylvania, USA

    Science.gov (United States)

    Unusual mortality events of smallmouth bass (SMB) have been observed in the Susquehanna River Basin annually since 2005 and have coincided with a decline in recruitment of young-of-year fish into the adult SMB population. In 2014, the Pennsylvania Department of Environmental Pro...

  2. River Morphology and River Channel Changes

    Institute of Scientific and Technical Information of China (English)

    CHANG Howard H

    2008-01-01

    River morphology has been a subject of great challenge to scientists and engineers who recognize that any effort with regard to river engineering must be based on a proper understanding of the morphological features involved and the responses to the imposed changes. In this paper,an overview of river morphology is presented from the geomorphic viewpoint. Included in the scope are the regime concept, river channel classification, thresholds in river morphology, and geomor-phic analysis of river responses. Analytical approach to river morphology based on the physical principles for the hydraulics of flow and sediment transport processes is also presented. The appli-cation of analytical river morphology is demonstrated by an example. Modeling is the modern tech-nique to determine both short-term and long-term river channel responses to any change in the en-vironment. The physical foundation of fluvial process-response must be applied in formatting a mathematical model. A brief introduction of the mathematical model FLUVIAL-12 is described.

  3. Photo Essay: An East Asian Circulation: Asa Mattice on the USS Juniata, 1883–1885

    Directory of Open Access Journals (Sweden)

    Robert Bickers

    2013-06-01

    Full Text Available On Tuesday, May 12, 1885, 210 men from the U.S. navy warships Juniata and Monocacy marched up Shanghai’s Nanjing Road, from the riverside Bund to the Shanghai racecourse, led by a sixteen-man band. There, on the recreation ground inside the track, they exercised and paraded for two hours, putting their field gun teams through their maneuvers, and in the afternoon the band played for the spectators. The weather was fine that day. Toward the end of the proceedings, before the men were paraded back through the streets of the foreign-run International Settlement to embark for the ships moored in the Huangpu River, the North China Herald (May 15, 1885, p. 552 recorded that “past Assistant Engineer Mattice of the Juniata took a photographic view of the battalion by the dry plate process.”

  4. Preservation of meandering river channels in uniformly aggrading channel belts

    NARCIS (Netherlands)

    van de Lageweg, W.I.; Schuurman, F.; Cohen, K.M.; van Dijk, W. M.; Shimizu, Y.; Kleinhans, M.G.

    2016-01-01

    Channel belt deposits from meandering river systems commonly display an internal architecture of stacked depositional features with scoured basal contacts due to channel and bedform migration across a range of scales. Recognition and correct interpretation of these bounding surfaces is essential to

  5. CHANNEL WIDENING DURING DEGRADATION OF ALLUVIAL RIVERS

    Institute of Scientific and Technical Information of China (English)

    Guangqian WANG; Junqiang XIA

    2001-01-01

    This paper first describes the phenomenon of channel widening during degradation of alluvial rivers,explains the mechanisms of channel widening, and analyzes the stability of cohesive riverbank. Then a one-dimensional mathematical model is developed to simulate the transport of non-uniform suspended sediments, with a sub-model for the simulation of channel widening, and is used to study the process of channel widening during degradation. The effects of different incident flow and sediment conditions and different riverbank material characteristics on channel widening and bed degradation are compared.Finally, main factors that control the deformation processes are identified.

  6. A Case Study on Collaboration: Sharing the Responsibility of Economic Development in Juniata Valley, Pennsylvania

    Science.gov (United States)

    Ward, Shakoor A.; Clark, Robert W.

    2013-01-01

    In an attempt to better understand the need and importance of the community college's role in economic development, this article takes a closer look at how collaboration in the Juniata Valley of Pennsylvania between Industrial Development Corporations (IDCs) of Mifflin and Juniata counties, career and technical centers, and other agencies is…

  7. THE FORMING CONDITIONS OF ALLUVIAL RIVER CHANNEL PATTERNS

    Institute of Scientific and Technical Information of China (English)

    Pu QI; Gouting LIANG; Zangying SUN; Honghai QI

    2002-01-01

    In normal fluvial processes the river channel is determined by river flows while the movement of river flows is contained by river channels. The relationship between the river morphology and its bend curvature shows that rivers with large bend curvatures always have narrow and deep channels and those with shallow and wide channels are always straight. The plan form of a river reaches is determined by the cross-sectional morphology. A meandering river reach may be developed under various water-sediment conditions as long as the narrow and deep channels are formed.

  8. River channel patterns: Braided, meandering, and straight

    Science.gov (United States)

    Leopold, Luna B.; 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

  9. Channel Planform Dynamics Monitoring and Channel Stability Assessment in Two Sediment-Rich Rivers in Taiwan

    Directory of Open Access Journals (Sweden)

    Cheng-Wei Kuo

    2017-01-01

    Full Text Available Recurrent flood events induced by typhoons are powerful agents to modify channel morphology in Taiwan’s rivers. Frequent channel migrations reflect highly sensitive valley floors and increase the risk to infrastructure and residents along rivers. Therefore, monitoring channel planforms is essential for analyzing channel stability as well as improving river management. This study analyzed annual channel changes along two sediment-rich rivers, the Zhuoshui River and the Gaoping River, from 2008 to 2015 based on satellite images of FORMOSAT-2. Channel areas were digitized from mid-catchment to river mouth (~90 km. Channel stability for reaches was assessed through analyzing the changes of river indices including braid index, active channel width, and channel activity. In general, the valley width plays a key role in braided degree, active channel width, and channel activity. These indices increase as the valley width expands whereas the braid index decreases slightly close to the river mouth due to the change of river types. This downstream pattern in the Zhuoshui River was interrupted by hydraulic construction which resulted in limited changes downstream from the weir, due to the lack of water and sediment supply. A 200-year flood, Typhoon Morakot in 2009, induced significant changes in the two rivers. The highly active landscape in Taiwan results in very sensitive channels compared to other regions. An integrated Sensitivity Index was proposed for identifying unstable reaches, which could be a useful reference for river authorities when making priorities in river regulation strategy. This study shows that satellite image monitoring coupled with river indices analysis could be an effective tool to evaluate spatial and temporal changes in channel stability in highly dynamic river systems.

  10. Meandering rivers - feedbacks between channel dynamics, floodplain and vegetation

    NARCIS (Netherlands)

    van Dijk, W.M.

    2013-01-01

    Rivers have distinctive channel patterns such as multi-channel braiding and single-channel meandering. Why these different river patterns emerge is only qualitatively understood. Yet, we have not been able to retain dynamic meandering in laboratory experiments. The main objective of this thesis was

  11. River channel adjustments in Southern Italy over the past 150 years and implications for channel recovery

    Science.gov (United States)

    Scorpio, Vittoria; Aucelli, Pietro P. C.; Giano, Salvatore I.; Pisano, Luca; Robustelli, Gaetano; Rosskopf, Carmen M.; Schiattarella, Marcello

    2015-12-01

    Multi-temporal GIS analysis of topographic maps and aerial photographs along with topographic and geomorphological surveys are used to assess evolutionary trends and key control factors of channel adjustments for five major rivers in southern Italy (the Trigno, Biferno, Volturno, Sinni and Crati rivers) to support assessment of channel recovery and river restoration. Three distinct phases of channel adjustment are identified over the past 150 years primarily driven by human disturbances. Firstly, slight channel widening dominated from the last decades of the nineteenth century to the 1950s. Secondly, from the 1950s to the end of the 1990s, altered sediment fluxes induced by in-channel mining and channel works brought about moderate to very intense incision (up to 6-7 m) accompanied by strong channel narrowing (up to 96%) and changes in channel configuration from multi-threaded to single-threaded patterns. Thirdly, the period from around 2000 to 2015 has been characterized by channel stabilization and local widening. Evolutionary trajectories of the rivers studied are quite similar to those reconstructed for other Italian rivers, particularly regarding the second phase of channel adjustments and ongoing transitions towards channel recovery in some reaches. Analyses of river dynamics, recovery potential and connectivity with sediment sources of the study reaches, framed in their catchment context, can be used as part of a wider interdisciplinary approach that views effective river restoration alongside sustainable and risk-reduced river management.

  12. Photo Essay: Notes on “The Voyage of the USS Juniata (1883–1885”

    Directory of Open Access Journals (Sweden)

    John Dowling

    2013-06-01

    Full Text Available The images included in the June 2013 Cross-Currents photo essay, “The Voyage of the USS Juniata (1883–1885,” are digital scans made from a set of five-by-eight-inch glass plate negatives depicting scenes from a three-year (1883–1885 naval expedition to the Far East by the USS Juniata. The photographer was Asa M. Mattice, an officer on board (figure 1. Mattice, a native of New York State, graduated from the U.S. Naval Academy at the head of his class as a cadet engineer in 1874 and was later appointed to the teaching staff at Annapolis. He served on the USS Juniata beginning on November 30, 1882, when the ship departed from New York to join five other ships at the Asiatic Squadron.

  13. River channel morphology and hydraulics properties due to introduction of plant basket hydraulic structures for river channel management

    Science.gov (United States)

    Kałuża, Tomasz; Radecki-Pawlik, Artur; Plesiński, Karol; Walczak, Natalia; Szoszkiewicz, Krzysztof; Radecki-Pawlik, Bartosz

    2016-04-01

    In the present time integrated water management is directly connected with management and direct works in river channels themselves which are taking into account morphological processes in rivers and improve flow conditions. Our work focused on the hydraulic and hydrodynamic consequences upon the introduction of the concept of the improvement of the hydromorphological conditions of the Flinta River in a given reach following river channel management concept. Based on a comprehensive study of the hydromorphological state of the river, four sections were selected where restoration measures can efficiently improve river habitat conditions in the river. For each section a set of technical and biological measures were proposed and implemented in practice. One of the proposed solutions was to construct plant basket hydraulic structures (PBHS) within the river channel, which are essentially plant barriers working as sediment traps, changing river channel morphology and are in line with concepts of Water Framework Directive. These relatively small structures work as crested weirs and unquestionably change the channel morphology. Along our work we show the results of three-year long (2013-2015) systematic measurements that provided information on the morphological consequences of introducing such structures into a river channel. Our main conclusions are as follows: 1. Plant basket hydraulic structures cause changes in hydrodynamic conditions and result in sediment accumulation and the formation of river backwaters upstream and downstream the obstacle; 2. The introduced plant basket hydraulic structures cause plant debris accumulation which influences the hydrodynamic flow conditions; 3. The installation of plant basket hydraulic structures on the river bed changes flow pattern as well as flow hydrodynamic conditions causing river braiding process; 4. The erosion rate below the plant basket hydraulic structures is due to the hydraulic work conditions of the PBHS and its

  14. 76 FR 13446 - Juniata Valley Railroad Company-Operation Exemption-SEDA-COG Joint Rail Authority

    Science.gov (United States)

    2011-03-11

    ... Surface Transportation Board Juniata Valley Railroad Company-Operation Exemption-SEDA-COG Joint Rail... is owned or leased by SEDA-COG Joint Rail Authority (SEDA-COG). JVRR states that the line it proposes to operate is an extension of its existing line of railroad it operates for SEDA- COG and that...

  15. Channel evolution on the dammed Elwha River, Washington, USA

    Science.gov (United States)

    Draut, A.E.; Logan, J.B.; Mastin, M.C.

    2011-01-01

    Like many rivers in the western U.S., the Elwha River, Washington, has changed substantially over the past century in response to natural and human forcing. The lower river is affected by two upstream dams that are slated for removal as part of a major river restoration effort. In preparation for studying the effects of dam removal, we present a comprehensive field and aerial photographic analysis of dam influence on an anabranching, gravel-bed river. Over the past century with the dams in place, loss of the upstream sediment supply has caused spatial variations in the sedimentary and geomorphic character of the lower Elwha River channel. Bed sediment is armored and better sorted than on the naturally evolving bed upstream of the dams. On time scales of flood seasons, the channel immediately below the lower dam is fairly stable, but progresses toward greater mobility downstream such that the lowermost portion of the river responded to a recent 40-year flood with bank erosion and bed-elevation changes on a scale approaching that of the natural channel above the dams. In general, channel mobility in the lowest 4 km of the Elwha River has not decreased substantially with time. Enough fine sediment remains in the floodplain that – given sufficient flood forcing – the channel position, sinuosity, and braiding index change substantially. The processes by which this river accesses new fine sediment below the dams (rapid migration into noncohesive banks and avulsion of new channels) allow it to compensate for loss of upstream sediment supply more readily than would a dammed river with cohesive banks or a more limited supply of alluvium. The planned dam removal will provide a valuable opportunity to evaluate channel response to the future restoration of natural upstream sediment supply.

  16. River Channel Migration: A Remote Sensing and GIS Analysis

    Science.gov (United States)

    Islam, Tariqul

    2010-12-01

    Remote sensing and geographic information system provide tools for quantitative and qualitative river morphological analysis. Bangladesh is a riverine, flood prone country and, the Padma and the Jamuna are two of major three rivers in the country. The aim of this research is to monitor the channel migration of the Padma and the Jamuna rivers since 1977 to 2004 using remote sensing and GIS. Four scenes for dry season's cloud free Landsat images were used in this study. Images were processed using PCI Geomatica and ArcGIS 9.3 was used for GIS analysis. The Landsat images were visualized and identified nine locations to investigate the channel migration. The images were classified into two broad categories, i.e. water and nonwater body. ArcGIS 9.3 was used to transfer these classified images into GIS layers. A standard measurement tool of ArcGIS was applied to measure the movement of river channel based on initial river channel in 1977. General trend of the Padma and the Jamuna river channel migration at locations A, B, C, D, F, G, H and I towards north, northeast and southwest eventually, north, northeast, east, east, west and west, respectively. The confluence point of the Padma and Jamuna (at location E) migrated toward southeast with high rate. During 1977-2004, it migrated about 9000m toward southeast. Trend of migration of the confluence point was faster than any other locations in the channel of the Padma river.

  17. 33 CFR 117.751 - Shark River (South Channel).

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Shark River (South Channel). 117.751 Section 117.751 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.751 Shark River...

  18. Columbia River Channel Improvement Project Rock Removal Blasting: Monitoring Plan

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Thomas J.; Johnson, Gary E.

    2010-01-29

    This document provides a monitoring plan to evaluate take as outlined in the National Marine Fisheries Service 2002 Biological Opinion for underwater blasting to remove rock from the navigation channel for the Columbia River Channel Improvement Project. The plan was prepared by the Pacific Northwest National Laboratory (PNNL) for the U.S. Army Corps of Engineers (USACE), Portland District.

  19. Linking channel hydrology with riparian wetland accretion in tidal rivers

    Science.gov (United States)

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

    2014-01-01

    hydrologic processes by which tide affects river channel and riparian morphology within the tidal freshwater zone are poorly understood yet are fundamental to predicting the fate of coastal rivers and wetlands as sea level rises. We investigated patterns of sediment accretion in riparian wetlands along the nontidal through oligohaline portion of two coastal plain rivers in Maryland, U.S., and how flow velocity, water level, and suspended sediment concentration (SSC) in the channel may have contributed to those patterns. Sediment accretion was measured over a 1 year period using artificial marker horizons, channel hydrology was measured over a 1 month period using acoustic Doppler current profilers, and SSC was predicted from acoustic backscatter. Riparian sediment accretion was lowest at the nontidal sites (mean and standard deviation = 8 ± 8 mm yr-1), highest at the upstream tidal freshwater forested wetlands (TFFW) (33 ± 28 mm yr-1), low at the midstream TFFW (12 ± 9 mm yr-1), and high at the oligohaline (fresh-to-brackish) marshes (19 ± 8 mm yr-1). Channel maximum flood and ebb velocity was twofold faster at the oligohaline than tidal freshwater zone on both tidal rivers, corresponding with the differences in in-channel SSC: The oligohaline zone's SSC was more than double the tidal freshwater zone's and was greater than historical SSC at the nontidal gages. The tidal wave characteristics differed between rivers, leading to significantly greater in-channel SSC during floodplain inundation in the weakly convergent than the strongly convergent tidal river. High sediment accretion at the upstream TFFW was likely due to high river discharge following a hurricane.

  20. Umpqua River Oregon Active Channel 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Umpqua River drains 12,103 square kilometers (4,673 square miles) in southwest Oregon before flowing into the Pacific Ocean at Winchester Bay near the city of...

  1. Umpqua River Oregon Active Channel 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Umpqua River drains 12,103 square kilometers (4,673 square miles) in southwest Oregon before flowing into the Pacific Ocean at Winchester Bay near the city of...

  2. Umpqua River Oregon Active Channel 1967

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Umpqua River drains 12,103 square kilometers (4,673 square miles) in southwest Oregon before flowing into the Pacific Ocean at Winchester Bay near the city of...

  3. Umpqua River Oregon Active Channel 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Umpqua River drains 12,103 square kilometers (4,673 square miles) in southwest Oregon before flowing into the Pacific Ocean at Winchester Bay near the city of...

  4. Umpqua River Oregon Active Channel 1994

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Umpqua River drains 12,103 square kilometers (4,673 square miles) in southwest Oregon before flowing into the Pacific Ocean at Winchester Bay near the city of...

  5. Umpqua River Oregon Active Channel 1939

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Umpqua River drains 12,103 square kilometers (4,673 square miles) in southwest Oregon before flowing into the Pacific Ocean at Winchester Bay near the city of...

  6. Predictive techniques for river channel evolution and maintenance

    Science.gov (United States)

    Nelson, J.M.

    1996-01-01

    Predicting changes in alluvial channel morphology associated with anthropogenic and natural changes in flow and/or sediment supply is a critical part of the management of riverine systems. Over the past few years, advances in the understanding of the physics of sediment transport in conjunction with rapidly increasing capabilities in computational fluid dynamics have yielded now approaches to problems in river mechanics. Techniques appropriate for length scales ranging from reaches to bars and bedforms are described here. Examples of the use of these computational approaches are discussed for three cases: (1) the design of diversion scenarios that maintain channel morphology in steep cobble-bedded channels in Colorado, (2) determination of channel maintenance flows for the preservation of channel islands in the Snake River in Idaho, and (3) prediction of the temporal evolution of deposits in lateral separation zones for future assessment of the impacts of various dam release scenarios on lateral separation deposits in the Colorado River in Grand Canyon. With continued development of their scientific and technical components, the methodologies described here can provide powerful tools for the management of river environments in the future.

  7. Quantifying habitat benefits of channel reconfigurations on a highly regulated river system, Lower Missouri River, USA

    Science.gov (United States)

    Erwin, Susannah O.; Jacobson, Robert B.; Elliott, Caroline M.

    2017-01-01

    We present a quantitative analysis of habitat availability in a highly regulated lowland river, comparing a restored reach with two reference reaches: an un-restored, channelized reach, and a least-altered reach. We evaluate the effects of channel modifications in terms of distributions of depth and velocity as well as distributions and availability of habitats thought to be supportive of an endangered fish, the pallid sturgeon (Scaphirhynchus albus). It has been hypothesized that hydraulic conditions that support food production and foraging may limit growth and survival of juvenile pallid sturgeon. To evaluate conditions that support these habitats, we constructed two-dimensional hydrodynamic models for the three study reaches, two located in the Lower Missouri River (channelized and restored reaches) and one in the Yellowstone River (least-altered reach). Comparability among the reaches was improved by scaling by bankfull discharge and bankfull channel area. The analysis shows that construction of side-channel chutes and increased floodplain connectivity increase the availability of foraging habitat, resulting in a system that is more similar to the reference reach on the Yellowstone River. The availability of food-producing habitat is low in all reaches at flows less than bankfull, but the two reaches in the Lower Missouri Riverchannelized and restored – display a threshold-like response as flows overtop channel banks, reflecting the persistent effects of channelization on hydraulics in the main channel. These high lateral gradients result in punctuated ecological events corresponding to flows in excess of bankfull discharge. This threshold effect in the restored reach remains distinct from that of the least-altered reference reach, where hydraulic changes are less abrupt and overbank flows more gradually inundate the adjacent floodplain. The habitat curves observed in the reference reach on the Yellowstone River may not be attainable within the

  8. Cyclic Sediment Trading Between Channel and River Bed Sediments

    Science.gov (United States)

    Haddadchi, A.

    2015-12-01

    Much of the previous work on sediment tracing has focused on determining either the initial sources of the sediment (soils derive from a particular rock type) or the erosion processes generating the sediment. However, alluvial stores can be both a source and sink for sediment transported by streams. Here geochemical and fallout radionuclide tracing of river-bed and alluvial sediments are used to determine the role of secondary sources, sediment stores, as potential sources of sediment leaving Emu Creek catchment, southeastern Queensland, Australia. Activity concentrations of 137Cs on the river sediments are consistent with channel erosion being the dominant source at all sites sampled along the river. To characterise the deposition and remobilisation cycles in the catchment, a novel geochemical tracing approach was used. Successive pockets of alluvium were treated as discrete sink terms within geochemical mixing models and their source contributions compared with those of river bed sediments collected adjacent to each alluvial pocket. Three different size fractions were examined; silts and clays (soil/rock type sources to river bed and alluvial sediments at each sampling site was identical for all three different size fractions, but varied along the stream. Combining these findings it is concluded that proximal alluvial stores dominated the supply of sediment to the river at each location, with this being particularly evident at the catchment outlet. Identical contribution of rock type sources to both river bed and alluvial pockets together with the dominant erosion being from channel banks indicates a high degree of 'trading' between the fluvial space and the alluvial space. Hence, management works aimed at primarily reducing the supply of sediments to the outlet of Emu Creek should focus on rehabilitation of channel banks in the lower catchment.

  9. 76 FR 11679 - Drawbridge Operation Regulation; Shark River (South Channel), Belmar, NJ

    Science.gov (United States)

    2011-03-03

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; Shark River (South Channel), Belmar... operation of the S71 Bridge across Shark River (South Channel), mile 0.8, at Belmar, NJ. The deviation is... INFORMATION: The S71 Bridge, a bascule lift drawbridge, across Shark River (South Channel), at mile 0.8,...

  10. Forming of single-thread channels and multiple channel rivers on Titan and Earth

    Science.gov (United States)

    Misiura, Katarzyna; Czechowski, Leszek

    2016-10-01

    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 multiple channel rivers are developed rather than single channel. This work is aimed to investigate the similarity and differences between these processes on Titan and the Earth.Numerical modelThe 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. We use the same numerical package that in our previous work [1] and [2], i.e. CCHE2D package.Parameters of the modelFor Titan we consider liquid corresponding to a Titan's rain (75% methane, 25% nitrogen) and water ice as material transported in rivers, for Earth the water and the quartz. We model evolution of the river for at least 100-200 days.Results and ConclusionsOur preliminary results indicate that suspended load is the main way of transport in simulated Titan's conditions. We also indicate that multiple channel rivers appears for larger range of slope on Titan (e.g. S=0.01-0.04) than on Earth (e.g. S=0.004-0.009). Also, for the same type of river, the grain size on Titan is at least 10 times larger than on Earth (1 cm for Titan versus 1 mm for the Earth). It is very interesting that on Titan multiple channel rivers appear even for very little discharge (e.g. Q=30m3/s) and for very large grain size (e.g. 10 cm). In the future we plan the experimental modelling in sediment basin to confirm results from computer modelling.References[1] Misiura, K., Czechowski, L., 2015. Numerical modelling of sedimentary structures in

  11. River channel's predisposition to ice jams: a geospatial model

    Science.gov (United States)

    De Munck, S.; Gauthier, Y.; Bernier, M.; Légaré, S.

    2012-04-01

    When dynamic breakup occurs on rivers, ice moving downstream may eventually stop at an obstacle when the volume of moving ice exceeds the transport capacity of the river, resulting into an ice jam. The suddenness and unpredictability of these ice jams are a constant danger to local population. Therefore forecasting methods are necessary to provide an early warning to these population. Nonetheless the morphological and hydrological factors controlling where and how the ice will jam are numerous and complex. Existing studies which exist on this topic are highly site specific. Therefore, the goal of this work is to develop a simplified geospatial model that would estimate the predisposition of any river channel to ice jams. The question here is not to predict when the ice will break up but rather to know where the released ice would be susceptible to jam. This paper presents the developments and preliminary results of the proposed approach. The initial step was to document the main factors identified in the literature, as potential cause for an ice jam. First, several main factors identified in the literature as potential cause for an ice jam have been selected: presence of an island, narrowing of the channel, sinuosity, presence of a bridge, confluence of rivers and slope break. The second step was to spatially represent, in 2D, the physical characteristics of the channel and to translate these characteristics into potential ice jamming factors. The Chaudiere River, south of Quebec City (Canada), was chosen as a test site. Tools from the GIS-based FRAZIL system have been used to generate these factors from readily available geospatial data and calcutate an "ice jam predisposition index" over regular-spaced segments along the entire channel. The resulting map was validated upon historical observations and local knowledge, collected in relationship with the Minister of Public Security.

  12. Port Areas and Approach Channels Sinoimeri by Rivers Sediment Transport

    Directory of Open Access Journals (Sweden)

    Konstantin N. Makarov

    2015-12-01

    Full Text Available When designing ports, one important task is to predict sinoimeri port areas and approach channels sandy or pebbly silt. On the basis of this forecast are determined by the methods of protection from sinoimeri, as well as the frequency and volume of maintenance dredging works. Out at sea the river flow becomes turbulent inertial jet. Friction on the bottom and the interaction with sea water leads to an overall reduction of jet velocity and its spreading. An important regularity is also spreading muddy river flow on the surface of the denser seawater. This creates conditions for rapid deposition of large fractions of the sediment on the bottom. The bulk of the sediment particles larger than 5 mm is deposited on the surface of the river bar and further transported along the shore wave energy currents. Outside of the bar shall be made only fine-grained material. The particle size of sediment deposited on the bottom outside of the bar decreases sharply with depth. Thus, sinoimeri of harbors and access channels is mainly suspended river sediments. To calculate the distribution of the river flow, in the coastal zone in the presence of long chore currents developed a special method that implements the theory of turbulent planar jet in a drifting thread. The solid portion of the jet flow that enters the waters of the port or channel as a result of increasing depth and, consequently, reduce turbidity settles, causing shoaling waters. The example of calculation of sinoimeri berth 1a in the port of Tuapse by solid flow of Tuapse river.

  13. River Channel Expansion Reveals Ice Sheet Runoff Variations

    Science.gov (United States)

    Overeem, I.; Hudson, B. D.; Welty, E.; LeWinter, A.; Mikkelsen, A. B.

    2013-12-01

    The Greenland Ice Sheet has been rapidly melting over the last decades. To quantify its contribution to global sea-level rise, we urgently need to understand flux of meltwater into proglacial rivers. Direct measurements of river runoff at the Greenlandic coast are sparse due to the dynamic braided channels with unstable banks, which makes in-situ discharge monitoring challenging. Here, we explore the use of ';inundation-discharge' relationships through analysis of both time-lapse camera imagery and MODIS remote-sensing reflectance data to provide us with a proxy record of river discharge for proglacial systems. We utilize MODIS band6 (mid IR 1628 - 1652 nm). Light in this band is strongly absorbed by water, and reflectance is not sensitive to sediment suspended in the water, making it an appropriate proxy for river braidplain inundation. Our focus is on two Greenlandic river systems; the Watson River near Kangerlussuaq and the Naujat Kuat River near Nuuk, to track band6 reflectance characteristics over all cloud-free days for the summers of 2000-2012. For validation, a ground-based inundation record is assembled from time-lapse imagery overlooking the Watson River for 2012. Exponential inundation-discharge relationships were established using our in-situ discharge records for the Watson River near Kangerlussuaq (2007-2012, R2=0.55) and the Naujat Kuat River near Nuuk (2011-2012, R2 = 0.42). Using these relationships to predict total annual river discharge proves reasonably accurate for most years of the observational record (varying between 96-86%). Interestingly, the extreme melt year of 2012 was not reliably predicted using the established relationship. We compared these predictions against an inundation record from the in-situ time-lapse camera and found that a ground-based observations track extreme discharge events more reliably (R2 = 0.60). This methodology allows us to extend existing river records back beyond the 5 or 2 years of in-situ observations

  14. Sediment supply controls equilibrium channel geometry in gravel rivers

    Science.gov (United States)

    Pfeiffer, Allison M.; Finnegan, Noah J.; Willenbring, Jane K.

    2017-03-01

    In many gravel-bedded rivers, floods that fill the channel banks create just enough shear stress to move the median-sized gravel particles on the bed surface (D50). Because this observation is common and is supported by theory, the coincidence of bankfull flow and the incipient motion of D50 has become a commonly used assumption. However, not all natural gravel channels actually conform to this simple relationship; some channels maintain bankfull stresses far in excess of the critical stress required to initiate sediment transport. We use a database of >300 gravel-bedded rivers and >600 10Be-derived erosion rates from across North America to explore the hypothesis that sediment supply drives the magnitude of bankfull shear stress relative to the critical stress required to mobilize the median bed surface grain size (τbf*/τc*). We find that τbf*/τc* is significantly higher in West Coast river reaches (2.35, n = 96) than in river reaches elsewhere on the continent (1.03, n = 245). This pattern parallels patterns in erosion rates (and hence sediment supplies). Supporting our hypothesis, we find a significant correlation between upstream erosion rate and local τbf*/τc* at sites where this comparison is possible. Our analysis reveals a decrease in bed surface armoring with increasing τbf*/τc*, suggesting channels accommodate changes in sediment supply through adjustments in bed surface grain size, as also shown through numerical modeling. Our findings demonstrate that sediment supply is encoded in the bankfull hydraulic geometry of gravel bedded channels through its control on bed surface grain size.

  15. Field intercomparison of channel master ADCP with RiverSonde Radar for measuring river discharge

    Science.gov (United States)

    Spain, P.; Marsden, R.; Barrick, D.; Teague, C.; Ruhl, C.

    2005-01-01

    The RiverSonde radar makes non-contact measurement of a horizontal swath of surface velocity across a river section. This radar, which has worked successfully at several rivers in the Western USA, has shown encouraging correlation with simultaneous measurements of average currents at one level recorded by an acoustic travel-time system. This work reports a field study intercomparing data sets from a 600 kHz Channel Master ADCP with the RiverSonde radar. The primary goal was to begin to explore the robustness of the radar data as a reliable index of discharge. This site Is at Three Mile Slough in Northern California, USA. The larger intent of the work is to examine variability in space and time of the radar's surface currents compared with subsurface flows across the river section. Here we examine data from a couple of periods with strong winds. ?? 2005 IEEE.

  16. Channel Response to Gravel Mining Activities in Mountain Rivers

    Institute of Scientific and Technical Information of China (English)

    José Luis López S.

    2004-01-01

    The removal of bed material from active river channels usually affects the bed profile of the streambed, causing progressive degradation upstream and downstream of the extraction site. These effects can extend for kilometers affecting hydraulic structures located in the vicinity of the river reach. In this paper, the geomorphic effects of gravel mining are reviewed and summarized. Some cases in Venezuelan streams are presented to illustrate the problem. To describe the processes of erosion and sedimentation in a gravel extraction pit, a recent developed mathematical model for the simulation of flow and sediment transport in gravel-cobble bed streams is applied to a hypothetical case of gravel mining in a river channel. A simple rectangular dredge pit is imposed as initial condition in the channel bed, and changes in bed elevations and grain size distribution of bed material are calculated by using the numerical model. The process of deposition within the pit, and the downstream and upstream migration of the erosion wave are well simulated by the model and closely resemble the phenomena observed in laboratory experiments. The response of the friction coefficient to the changes in flow and bed elevations shows the importance in modeling adequately flow resistance and sediment transport in gravel-cobble bed streams.

  17. Groundwater controls on biogeomorphic succession and river channel morphodynamics

    Science.gov (United States)

    Bätz, N.; Colombini, P.; Cherubini, P.; Lane, S. N.

    2016-10-01

    Biogeomorphic succession describes feedbacks between vegetation succession and fluvial processes that, at the decadal timescale, lead to a transition from bare river-deposited sediment to fully developed riparian forest. Where the rate of stabilization by biogeomorphic succession is greater than the rate of ecological disturbance by fluvial processes, a river is likely to evolve into less dynamic states. While river research has frequently considered the physical dimensions of morphodynamics, less is known about physical controls on succession rates, and how these impact stream morphodynamics. Here we test the hypothesis that groundwater dynamics influence morphodynamics via the rate of biogeomorphic succession. We applied historic imagery analysis in combination with dendroecological methods for willows growing on young gravelly fluvial landforms along a steep groundwater-depth gradient. We determined the following: floodplain morphodynamics and plant encroachment at the decadal scale, pioneer willow growth rates, and their relationships to hydrological variables. Willow growth rates were correlated with moisture availability (groundwater, discharge, and precipitation variability) in the downwelling reach, while little correlation was found in the upwelling reach. After a reduction in ecological disturbance frequency, data suggest that where groundwater is upwelling, biogeomorphic succession is fast, the engineering effect of vegetation is quickly established, and hence channel stability increased and active channel width reduces. Where groundwater is downwelling, deeper and more variable, biogeomorphic succession is slower, the engineering effect is reduced, and a wider active width is maintained. Thus, groundwater is an important control on biogeomorphic feedbacks intensity and, through the stabilizing effect of vegetation, may drive long-term river channel morphodynamics.

  18. Numerical modelling of channel migration with application to laboratory rivers

    Institute of Scientific and Technical Information of China (English)

    Jian SUN; Bin-liang LIN; Hong-wei KUANG

    2015-01-01

    The paper presents the development of a morphological model and its application to experimental model rivers. The model takes into account the key processes of channel migration, including bed deformation, bank failure and wetting and drying. Secondary flows in bends play an important role in lateral sediment transport, which further affects channel migration. A new formula has been derived to predict the near-bed secondary flow speed, in which the magnitude of the speed is linked to the lateral water level gradient. Since only non-cohesive sediment is considered in the current study, the bank failure is modelled based on the concept of submerged angle of repose. The wetting and drying process is modelled using an existing method. Comparisons between the numerical model predictions and experimental observations for various discharges have been made. It is found that the model predicted channel planform and cross-sectional shapes agree generally well with the laboratory observations. A scenario analysis is also carried out to investigate the impact of secondary flow on the channel migration process. It shows that if the effect of secondary flow is ignored, the channel size in the lateral direction will be seriously underestimated.

  19. Influence of bedrock on river hydrodynamics and channel geometry

    Science.gov (United States)

    Rennie, C. D.; Church, M. A.; Venditti, J. G.; Bomhof, J.; Adderley, C.

    2013-12-01

    We present an acoustic Doppler current profiler (aDcp) survey of a 524 km long reach of Fraser River, British Columbia, Canada, as it passes through the Fraser Canyons. The channel alternates between gravel-bedded reaches that are incised into semi-consolidated glacial deposits and bedrock-bound reaches (7.7% of the reach between the towns of Quesnel and Hope). A continuous centreline aDcp survey was employed to measure longitudinal variation in slope, depth, depth-averaged velocity, and shear velocity. A total of 71 aDcp sectional surveys throughout the reach provided section widths (w), section-averaged depths (d), velocity distributions, and discharge (Q). Finally, air photo analysis using Google imagery provided channel widths at 0.5 km spacing. The survey reach was subdivided into 10 morphological sub-reaches, which ranged from alluvial gravel-bed reaches with relatively moderate slope to steep non-alluvial rock-walled canyons. The resulting data provide a unique opportunity to evaluate the influence of bedrock confinement on river hydrodynamics and channel geometry. Continuous centreline longitudinal aDcp data and the widths from air photo analysis were grouped within each sub-reach based on presence of bedrock confinement on both banks, either bank, or neither bank. The results demonstrate that river widths decreased and water depths, flow velocities, and shear velocities increased from the alluvial sub-reaches to the semi-alluvial reaches to the canyon reaches. Within each sub-reach, locations with bedrock encroachment on both banks were also narrower and deeper, but had lower depth-averaged velocity and shear velocity. Sectional geometry data were homogenized along the river (to compensate increasing flows at tributary junctions) by computing w/Q^{1/2} and d/Q^{1/3}, following commonly observed scaling relations. Alluvial reaches are 2.3x wider than rock-bound reaches (from the more abundant imagery data) and 0.60x as deep (from aDcp sections), implying

  20. Observations of the Behavior and Distribution of Fish in Relation to the Columbia River Navigation Channel and Channel Maintenance Activities

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Thomas J.; Ploskey, Gene R.; Johnson, R. L.; Mueller, Robert P.; Weiland, Mark A.; Johnson, P. N.

    2001-10-19

    This report is a compilation of 7 studies conducted for the U.S. Army Corps of Engineers between 1995 and 1998 which used hydroacoustic methods to study the behavior of migrating salmon in response to navigation channel maintenance activities in the lower Columbia River near river mile 45. Differences between daytime and nighttime behavior and fish densities were noted. Comparisons were made of fish distribution across the river (in the channel, channel margin or near shore) and fish depth upstream and downstream of dikes, dredges, and pile driving areas.

  1. Impact of a large flood on mountain river habitats, channel morphology, and valley infrastructure

    Science.gov (United States)

    Hajdukiewicz, Hanna; Wyżga, Bartłomiej; Mikuś, Paweł; Zawiejska, Joanna; Radecki-Pawlik, Artur

    2016-11-01

    The Biała River, Polish Carpathians, was considerably modified by channelization and channel incision in the twentieth century. To restore the Biała, establishing an erodible corridor was proposed in two river sections located in its mountain and foothill course. In these sections, longer, unmanaged channel reaches alternate with short, channelized reaches; and channel narrowing and incision increases in the downstream direction. In June 2010 an 80-year flood occurred on the river; and this study aims at determining its effects on physical habitat conditions for river biota, channel morphology, and valley-floor infrastructure. Surveys of 10 pairs of closely located, unmanaged and channelized cross sections, performed in 2009 and in the late summer 2010, allowed us to assess the flood-induced changes to physical habitat conditions. A comparison of channel planforms determined before (2009) and after (2012) the flood provided information on the degree of channel widening as well as changes in the width of particular elements of the river's active zone in eight stretches of the Biała. The impact of the flood on valley-floor infrastructure was confronted with the degree of river widening in unmanaged and channelized river reaches. Before the flood, unmanaged cross sections were typified by finer bed material and greater lateral variability in depth-averaged and near-bed flow velocity than channelized cross sections. The flood tended to equalize habitat conditions in both types of river cross sections, obliterating differences (in particular physical habitat parameters) between channelized and unmanaged channel reaches. River widening mostly reflected an increase in the area of channel bars, whereas the widening of low-flow channels was less pronounced. A comparison of channel planform from 2009 and 2012 indicated that intense channel incision typical of downstream sections limited river widening by the flood. Active channel width increased by half in the unmanaged

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

    Science.gov (United States)

    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

  3. River sedimentation and channel bed characteristics in northern Ethiopia

    Science.gov (United States)

    Demissie, Biadgilgn; Billi, Paolo; Frankl, Amaury; Haile, Mitiku; Lanckriet, Sil; Nyssen, Jan

    2016-04-01

    Excessive sedimentation and flood hazard are common in ephemeral streams which are characterized by flashy floods. The purposes of this study was to investigate the temporal variability of bio-climatic factors in controlling sediment supply to downstream channel reaches and the effect of bridges on local hydro-geomorphic conditions in causing the excess sedimentation and flood hazard in ephemeral rivers of the Raya graben (northern Ethiopia). Normalized Difference Vegetation Index (NDVI) was analyzed for the study area using Landsat imageries of 1972, 1986, 2000, 2005, 2010, and 2012). Middle term, 1993-2011, daily rainfall data of three meteorological stations, namely, Alamata, Korem and Maychew, were considered to analyse the temporal trends and to calculate the return time intervals of rainfall intensity in 24 hours for 2, 5, 10 and 20 years using the log-normal and the Gumbel extreme events method. Streambed gradient and bed material grain size were measured in 22 river reaches (at bridges and upstream). In the study catchments, the maximum NDVI values were recorded in the time interval from 2000 to 2010, i.e. the decade during which the study bridges experienced the most severe excess sedimentation problems. The time series analysis for a few rainfall parameters do not show any evidence of rainfall pattern accountable for an increase in sediment delivery from the headwaters nor for the generation of higher floods with larger bedload transport capacities. Stream bed gradient and bed material grain size data were measured in order to investigate the effect of the marked decrease in width from the wide upstream channels to the narrow recently constructed bridges. The study found the narrowing of the channels due to the bridges as the main cause of the thick sedimentation that has been clogging the study bridges and increasing the frequency of overbank flows during the last 15 years. Key terms: sedimentation, ephemeral streams, sediment size, bridge clogging

  4. Comparison of planform multi-channel network characteristics of alluvial and bedrock constrained large rivers

    Science.gov (United States)

    Carling, P. A.; Meshkova, L.; Robinson, R. A.

    2011-12-01

    The Mekong River in northern Cambodia is an multi-channel mixed bedrock-alluvial river but it was poorly researched until present. Preliminary study of the Mekong geomorphology was conducted by gathering existing knowledge of its geological and tectonic settings, specific riparian vegetation and ancient alluvial terraces in which the river has incised since the Holocene. Altogether this process has allowed a geomorphological portrait of the river to be composed within the Quaternary context. Following this outline, the planform characteristics of the Mekong River network are compared, using analysis of channel network and islands configurations, with the fluvial patterns of the Orange River (South Africa), Upper Columbia River (Canada) and the Ganga River (India, Bangladesh). These rivers are selected as examples of multi-channel mixed bedrock alluvial, anastomosed alluvial and braided alluvial rivers respectively. Network parameters such as channel bifurcation angles asymmetry, sinuosity, braid intensity and island morphometric shape metrics are compared and contrasted between bedrock and alluvial systems. In addition, regional and local topographic trend surfaces produced for each river planform help explain the local changes in river direction and the degree of anastomosis, and distinguish the bedrock-alluvial rivers from the alluvial rivers. Variations between planform characteristics are to be explained by channel forming processes and in the case of mixed bedrock-alluvial rivers mediated by structural control. Channel metrics (derived at the reach-scale) provide some discrimination between different multi-channel patterns but are not always robust when considered singly. In contrast, island shape metrics (obtained at subreach-scale) allow robust discrimination between alluvial and bedrock systems.

  5. CHANNEL SHRINKAGE AND ITS INSTABILITY IN THE LOWER YELLOW RIVER1

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    From the mid 1980s through the late 1990s, the channel of the lower Yellow River experienced serious shrinkage, which has decreased the flood conveyance of the channel and the sediment carrying capacity of the flow, raised the water levels of floods, and, thus, severely threatened the safety of flood control along the river. The completion of Xiaolangdi Dam in 1999 could help mitigate the channel shrinkage problem, but the situation has not changed yet. This paper analyses the characteristics, mechanisms, and conditions resulting in channel shrinkage, points out channel instabilities, and puts forward approaches of channel rehabilitation.

  6. 33 CFR 165.508 - Security Zone; Georgetown Channel, Potomac River, Washington, DC.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zone; Georgetown Channel, Potomac River, Washington, DC. 165.508 Section 165.508 Navigation and Navigable Waters COAST GUARD... § 165.508 Security Zone; Georgetown Channel, Potomac River, Washington, DC. (a) Definitions. (1)...

  7. Tidal impact on the division of river discharge and distributary channels in the Mahakam Delta

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Brye, de B.; Vermeulen, B.; Deleersnijder, E.

    2011-01-01

    Bifurcations in tidally influenced deltas distribute river discharge over downstream channels, asserting a strong control over terrestrial runoff to the coastal ocean. Whereas the mechanics of river bifurcations is well-understood, junctions in tidal channels have received comparatively little atten

  8. On how spatial variations of channel width influence river profile curvature

    Science.gov (United States)

    Ferrer-Boix, Carles; Chartrand, Shawn M.; Hassan, Marwan A.; Martín-Vide, Juan P.; Parker, Gary

    2016-06-01

    Longitudinal profiles of alluvial rivers usually exhibit upward-concave curvatures at equilibrium. River profile concavity has been primarily attributed to sediment downstream fining and to streamwise increments of water discharge. Conversely, upward-convex profiles have been typically associated with tectonic and geologic controls and with outlet base-level drops. Equations to describe river profiles at equilibrium developed from mass conservation principles do not consider longitudinal changes in channel width. This study addresses how variations in channel width can also act to control the curvature of longitudinal profiles. We develop a new theoretical framework in which the role on river profiles of downstream variations of channel width, flow discharge, bed roughness, and surface texture are explicitly shown. Unlike classical approaches for river profile evolution, this novel framework identifies physical domains for rivers to develop upward-concave/convex longitudinal profiles depending on channel width and flow discharge gradients flow intensity and surface texture.

  9. 77 FR 70372 - Drawbridge Operation Regulation; Shark River (South Channel), Avon Township, NJ

    Science.gov (United States)

    2012-11-26

    ... SECURITY Coast Guard 33 CFR Part 117 RIN 1625-AA09 Drawbridge Operation Regulation; Shark River (South..., across Shark River (South Channel) at Avon Township, NJ. The existing regulation contains a drawbridge... Transportation (NJDOT) to replace the existing bascule bridge, which carries S35 over Shark River (South...

  10. Dynamic aspects of large woody debris in river channels

    Science.gov (United States)

    Vergaro, Alexandra; Caporali, Enrica; Becchi, Ignazio

    2015-04-01

    Large Woody Debris (LWD) are an integral component of the fluvial environment. They represent an environmental resource, but without doubt they represent also a risk factor for the amplification that could give to the destructive power of a flood event. While countless intervention in river channels have reintroduced wood in rivers with restoration and banks protection aims, during several flash flood events LWD have had a great part in catastrophic consequences, pointing out the urgency of an adequate risk assessment procedure. At present wood dynamics in rivers is not systematically considered within the procedures for the elaboration of hazard maps resulting in loss of prediction accuracy and underestimation of hazard impacts. The assessment inconsistency comes from the complexity of the question: several aspects in wood processes are not yet well known and the superposition of different physical phenomena results in great difficulty to predict critical scenarios. The presented research activity has been aimed to improve management skills for the assessment of the hydrologic risk associated to the presence of large woody debris in rivers, improving knowledge about LWD dynamic processes and proposing effective tools for monitoring and mapping river catchments vulnerability. Utilizing critical review of the published works, field surveys and experimental investigations LWD damaging potential has been analysed to support the identification of the exposed sites and the redaction of hazard maps, taking into account that a comprehensive procedure has to involve: a) Identification of the critical cross sections; b) Evaluation of wood availability in the river catchment; c) Prediction of hazard scenarios through the estimation of water discharge, wood recruitment and entrainment, wood transport and destination. Particularly, a survey sheets form for direct measurements has been implemented and tested in field to provide an investigation instruments for wood and river

  11. SEASONAL FORAGING BY CHANNEL CATFISH ON TERRESTRIALLY BURROWING CRAYFISH IN A FLOODPLAIN-RIVER ECOSYSTEM

    Science.gov (United States)

    The seasonal use of terrestrially burrowing crayfish as a food item by channel catfish Ictalurus punctatus was studied in channelized and non-channelized sections of the Yockanookany River (Mississippi, USA). During seasonal inundation of the floodplains, the crayfish occupied o...

  12. Channel-conveyance capacity, channel change, and sediment transport in the lower Puyallup, White, and Carbon Rivers, western Washington

    Science.gov (United States)

    Czuba, Jonathan A.; Czuba, Christiana R.; Magirl, Chistopher S.; Voss, Frank D.

    2010-01-01

    Draining the volcanic, glaciated terrain of Mount Rainier, Washington, the Puyallup, White, and Carbon Rivers convey copious volumes of water and sediment down to Commencement Bay in Puget Sound. Recent flooding in the lowland river system has renewed interest in understanding sediment transport and its effects on flow conveyance throughout the lower drainage basin. Bathymetric and topographic data for 156 cross sections were surveyed in the lower Puyallup River system by the U.S. Geological Survey (USGS) and were compared with similar datasets collected in 1984. Regions of significant aggradation were measured along the Puyallup and White Rivers. Between 1984 and 2009, aggradation totals as measured by changes in average channel elevation were as much as 7.5, 6.5, and 2 feet on the Puyallup, White, and Carbon Rivers, respectively. These aggrading river sections correlated with decreasing slopes in riverbeds where the rivers exit relatively confined sections in the upper drainage and enter the relatively unconstricted valleys of the low-gradient Puget Lowland. Measured grain-size distributions from each riverbed showed a progressive fining downstream. Analysis of stage-discharge relations at streamflow-gaging stations along rivers draining Mount Rainier demonstrated the dynamic nature of channel morphology on river courses influenced by glaciated, volcanic terrain. The greatest rates of aggradation since the 1980s were in the Nisqually River near National (5.0 inches per year) and the White River near Auburn (1.8 inches per year). Less pronounced aggradation was measured on the Puyallup River and the White River just downstream of Mud Mountain Dam. The largest measured rate of incision was measured in the Cowlitz River at Packwood (5.0 inches per year). Channel-conveyance capacity estimated using a one-dimensional hydraulic model decreased in some river reaches since 1984. The reach exhibiting the largest decrease (about 20-50 percent) in channel

  13. The role of river trajectories and channel recovery potential within sustainable river management: some case studies from southern Italy

    Science.gov (United States)

    Rosskopf, Carmen Maria; Scorpio, Vittoria; Patrizio Ciro Aucelli, Pietro

    2016-04-01

    Most of Italian and European rivers have undergone notable channel adjustments since the last 150-200 years. Major adjustments fall within the second half of the last century and consisted in overall channel narrowing and degradation, accompanied by important pattern changes. In the cases of the six investigated rivers located in southern Italy (namely Trigno, Biferno, Fortore, Volturno, Sinni and Crati), major adjustments occurred from the 1950s to the end of the 1990s. They consisted in channel narrowing up to 98%, bed level lowering from -2 to -10m and extensive changes from multi-thread to single thread pattern that led to the abandonment of extensive channel areas and consistent increase of floodplain and terraced areas. The integrated analysis of river trajectories and potential control factors, both of natural and anthropic origin, showed that human disturbances, especially gravel mining and river control works, are key driving factors of channel adjustments. Furthermore, the presence of major hydraulic structures along the rivers Biferno, Fortore, Sinni and Trigno significantly influenced the amounts of channel adjustments which are sharply higher within the reaches located downstream of such structures. Considering the last 15-20 years, most of the evolutionary trajectories of the investigated reaches highlight ongoing channel stabilization or even some appreciable channel recovery. Particularly, channel widening had occurred in those reaches that are not under the direct influence of major hydraulic structures (check-dams and dams) and in which in-channel interventions had pratically ceased and woody riparian vegetation developed only in a discontinuous manner. Conversely, the reaches that are located immediately downstream of major hydraulic structures, in which control works are placed very close to the actual riverbanks and/or a continuous riparian forest has developed, appear stable, only locally affected by very slight widening, or even affected by

  14. Investigating the accuracy of photointerpreted unvegetated channel widths in a braided river system: a Platte River case study

    Science.gov (United States)

    Werbylo, Kevin L.; Farnsworth, Jason M.; Baasch, David M.; Farrell, Patrick D.

    2017-02-01

    The central Platte River in Nebraska, USA, has undergone substantial channel narrowing since basin settlement in the mid-nineteenth century. Many researchers have studied the causes of channel narrowing and its implications for endangered species that use wide, shallow channel segments with barren sandbars. As a result, changes in metrics such as unvegetated channel width have been studied. With few exceptions, these measures are estimated from aerial imagery without mention of error in relation to actual channel conditions and/or investigator bias. This issue is not unique to central Platte River studies, as a general lack of commentary is apparent regarding the direct comparison of channel planform characteristics interpreted from aerial imagery relative to those measured in the field. Here we present a case study where data collected by the Platte River Recovery Implementation Program was used to make multiple comparisons using three years of field-measured unvegetated channel widths and those photointerpreted from aerial imagery. Widths were interpreted by three investigators, who identified similar widths in almost all cases. Photointerpretation from imagery collected during the fall resulted in unvegetated width estimates that were more consistent with field measurments than estimates derived using imagery collected in June. Differences were attributed to three main factors: (1) influences of discharge on photointerpretation of unvegetated channel width; (2) increases in vegetative cover throughout the growing season; and (3) resolution of imagery. Most importantly, we concluded that photointerpretation of unvegetated widths from imagery collected during high flows can result in significant over estimation of unvegetated channel width.

  15. Ecosystem metabolism and nutrient dynamics in the main channel and backwaters of the Upper Mississippi River

    Science.gov (United States)

    Houser, Jeff N.; Bartsch, Lynn; Richardson, William B.; Rogala, James T.; Sullivan, John F.

    2015-01-01

    Photosynthesis and respiration are primary drivers of dissolved oxygen dynamics in rivers. We measured dissolved oxygen dynamics, aquatic ecosystem metabolism, algal abundance and nutrient concentrations at main channel and backwater sites on a reach of the Upper Mississippi River that borders the states of Wisconsin and Minnesota (U.S.A.). We asked (i) how ecosystem metabolism rates, dissolved oxygen dynamics and nutrient concentrations differed in the main channel and in backwaters, (ii) whether ecosystem metabolism relates to solar irradiance, nutrient concentration, algal abundance, temperature and river discharge and (iii) whether the relationships between ecosystem metabolism and these environmental factors differs between the main channel and backwaters.

  16. Large-scale dam removal on the Elwha River, Washington, USA: River channel and floodplain geomorphic change

    Science.gov (United States)

    East, Amy E.; Pess, George R.; Bountry, Jennifer A.; Magirl, Christopher S.; Ritchie, Andrew C.; Logan, Joshua B.; Randle, Timothy J.; Mastin, Mark C.; Minear, Justin T.; Duda, Jeffrey J.; Liermann, Martin C.; McHenry, Michael L.; Beechie, Timothy J.; Shafroth, Patrick B.

    2015-01-01

    A substantial increase in fluvial sediment supply relative to transport capacity causes complex, large-magnitude changes in river and floodplain morphology downstream. Although sedimentary and geomorphic responses to sediment pulses are a fundamental part of landscape evolution, few opportunities exist to quantify those processes over field scales. We investigated the downstream effects of sediment released during the largest dam removal in history, on the Elwha River, Washington, USA, by measuring changes in riverbed elevation and topography, bed sediment grain size, and channel planform as two dams were removed in stages over two years. As 10.5 million t (7.1 million m3) of sediment was released from two former reservoirs, downstream dispersion of a sediment wave caused widespread bed aggradation of ~ 1 m (greater where pools filled), changed the river from pool-riffle to braided morphology, and decreased the slope of the lowermost river. The newly deposited sediment, which was finer than most of the pre-dam-removal bed, formed new bars (largely pebble, granule, and sand material), prompting aggradational channel avulsion that increased the channel braiding index by almost 50%. As a result of mainstem bed aggradation, floodplain channels received flow and accumulated new sediment even during low to moderate flow conditions. The river system showed a two- to tenfold greater geomorphic response to dam removal (in terms of bed elevation change magnitude) than it had to a 40-year flood event four years before dam removal. Two years after dam removal began, as the river had started to incise through deposits of the initial sediment wave, ~ 1.2 million t of new sediment (~ 10% of the amount released from the two reservoirs) was stored along 18 river km of the mainstem channel and 25 km of floodplain channels. The Elwha River thus was able to transport most of the released sediment to the river mouth. The geomorphic alterations and changing bed sediment grain size along

  17. Reprint of: Large-scale dam removal on the Elwha River, Washington, USA: River channel and floodplain geomorphic change

    Science.gov (United States)

    East, Amy E.; Pess, George R.; Bountry, Jennifer A.; Magirl, Christopher S.; Ritchie, Andrew C.; Logan, Joshua B.; Randle, Timothy J.; Mastin, Mark C.; Minear, Justin T.; Duda, Jeffrey J.; Liermann, Martin C.; McHenry, Michael L.; Beechie, Timothy J.; Shafroth, Patrick B.

    2015-10-01

    A substantial increase in fluvial sediment supply relative to transport capacity causes complex, large-magnitude changes in river and floodplain morphology downstream. Although sedimentary and geomorphic responses to sediment pulses are a fundamental part of landscape evolution, few opportunities exist to quantify those processes over field scales. We investigated the downstream effects of sediment released during the largest dam removal in history, on the Elwha River, Washington, USA, by measuring changes in riverbed elevation and topography, bed sediment grain size, and channel planform as two dams were removed in stages over two years. As 10.5 million t (7.1 million m3) of sediment was released from two former reservoirs, downstream dispersion of a sediment wave caused widespread bed aggradation of 1 m (greater where pools filled), changed the river from pool-riffle to braided morphology, and decreased the slope of the lowermost river. The newly deposited sediment, which was finer than most of the pre-dam-removal bed, formed new bars (largely pebble, granule, and sand material), prompting aggradational channel avulsion that increased the channel braiding index by almost 50%. As a result of mainstem bed aggradation, floodplain channels received flow and accumulated new sediment even during low to moderate flow conditions. The river system showed a two- to tenfold greater geomorphic response to dam removal (in terms of bed elevation change magnitude) than it had to a 40-year flood event four years before dam removal. Two years after dam removal began, as the river had started to incise through deposits of the initial sediment wave, 1.2 million t of new sediment ( 10% of the amount released from the two reservoirs) was stored along 18 river km of the mainstem channel and 25 km of floodplain channels. The Elwha River thus was able to transport most of the released sediment to the river mouth. The geomorphic alterations and changing bed sediment grain size along the

  18. River channel network design for drought and flood control: A case study of Xiaoqinghe River basin, Jinan City, China.

    Science.gov (United States)

    Cui, Baoshan; Wang, Chongfang; Tao, Wendong; You, Zheyuan

    2009-08-01

    Vulnerability of river channels to urbanization has been lessened by the extensive construction of artificial water control improvements. The challenge, however, is that traditional engineering practices on isolated parts of a river may disturb the hydrologic continuity and interrupt the natural state of ecosystems. Taking the Xiaoqinghe River basin as a whole, we developed a river channel network design to mitigate river risks while sustaining the river in a state as natural as possible. The river channel risk from drought during low-flow periods and flood during high-flow periods as well as the potential for water diversion were articulated in detail. On the basis of the above investigation, a network with "nodes" and "edges" could be designed to relieve drought hazard and flood risk respectively. Subsequently, the shortest path algorithm in the graph theory was applied to optimize the low-flow network by searching for the shortest path. The effectiveness assessment was then performed for the low-flow and high-flow networks, respectively. For the former, the network connectedness was evaluated by calculating the "gamma index of connectivity" and "alpha index of circuitry"; for the latter, the ratio of flood-control capacity to projected flood level was devised and calculated. Results show that the design boosted network connectivity and circuitry during the low-flow periods, indicating a more fluent flow pathway, and reduced the flood risk during the high-flow periods.

  19. Channel centerline for the Rogue River, Oregon in 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Rogue River drains 13,390 square kilometers of southwestern Oregon before flowing into the Pacific Ocean near the town of Gold Beach, Oregon. The Rogue River...

  20. Channel centerline for the Rogue River, Oregon in 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Rogue River drains 13,390 square kilometers of southwestern Oregon before flowing into the Pacific Ocean near the town of Gold Beach, Oregon. The Rogue River...

  1. Water-Quality Monitoring in Response to Young-of-the-Year Smallmouth Bass (Micropterus dolomieu) Mortality in the Susquehanna River and Major Tributaries, Pennsylvania: 2008

    Science.gov (United States)

    Chaplin, Jeffrey J.; Crawford, J. Kent; Brightbill, Robin A.

    2009-01-01

    Mortalities of young-of-the-year (YOY) smallmouth bass (Micropterus dolomieu) recently have occurred in the Susquehanna River due to Flavobacterium columnare, a bacterium that typically infects stressed fish. Stress factors include but are not limited to elevated water temperature and low dissolved oxygen during times critical for survival and development of smallmouth bass (May 1 through July 31). The infections were first discovered in the Susquehanna River and major tributaries in the summer months of 2005 but also were prevalent in 2007. The U.S. Geological Survey, Pennsylvania Fish and Boat Commission, Pennsylvania Department of Environmental Protection, and PPL Corporation worked together to monitor dissolved oxygen, water temperature, pH, and specific conductance on a continuous basis at seven locations from May through mid October 2008. In addition, nutrient concentrations, which may affect dissolved-oxygen concentrations, were measured once in water and streambed sediment at 25 locations. Data from water-quality meters (sondes) deployed as pairs showed daily minimum dissolved-oxygen concentration at YOY smallmouth-bass microhabitats in the Susquehanna River at Clemson Island and the Juniata River at Howe Township Park were significantly lower (p-value < 0.0001) than nearby main-channel habitats. The average daily minimum dissolved-oxygen concentration during the critical period (May 1-July 31) was 1.1 mg/L lower in the Susquehanna River microhabitat and 0.3 mg/L lower in the Juniata River. Daily minimum dissolved-oxygen concentrations were lower than the applicable national criterion (5.0 mg/L) in microhabitat in the Susquehanna River at Clemson Island on 31 days (of 92 days in the critical period) compared to no days in the corresponding main-channel habitat. In the Juniata River, daily minimum dissolved-oxygen concentration in the microhabitat was lower than 5.0 mg/L on 20 days compared to only 5 days in the main-channel habitat. The maximum time periods

  2. Metals in edible fish from Vistula River and Dead Vistula River channel, Baltic Sea.

    Science.gov (United States)

    Wyrzykowska, Barbara; Falandysz, Jerzy; Jarzyńska, Grażyna

    2012-01-01

    Metals including Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, Sr and Zn were determined in muscle tissue of 12 fish species by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and cold vapour-atomic absorption spectroscopy (CV-AAS). Fish were collected from Vistula River at lower course and Dead Vistula River channel in south of Baltic Sea in Poland. The fish species examined include Round Goby (Neogobius melanostomus), Crucian Carp (Carassius carassius), Bull-rout (Myoxocephalus scorpius), Tench (Tinca tinca), Bream (Abramis brama), Burbot (Lota lot), Perch (Perca perca), Roach (Rutilus rutilus), Silver Carp (Hypophthalmichthys molitrix), Pikeperch (Stizostediun lucioperca), Brown salmon (Salmo trutta m. Trutta) and Eel (Anguilla anguilla). The median values of metal concentrations in fresh muscle tissue of 11 fish species varied as follows: Al < 0.5-60; Ba < 0.05-0.31; Ca 120-1800; Cd < 0.05-0.096; Co < 0.10; Cr < 0.10-0.50; Cu < 0.15-0.77; Fe 1.5-21; Hg 0.0058-0.65; K 1800-4200; Mg 130-560; Mn 0.12-0.59; Na 350-840; Ni < 0.2-0.31; Pb < 0.75; Sr 0.079-2.9; Zn 3.3-23 μg/g fresh weight. The Target Hazard Quotient (THQ) values calculated in this study for Cd and Hg from muscles of fish species collected from Vistula River were low in the range of 0.4 for Hg and 0.8 for Cd.

  3. Characterization of geomorphic units in the alluvial valleys and channels of Gulf Coastal Plain rivers in Texas, with examples from the Brazos, Sabine, and Trinity Rivers, 2010

    Science.gov (United States)

    Coffman, David K.; Malstaff, Greg; Heitmuller, Franklin T.

    2011-01-01

    The U.S. Geological Survey, in cooperation with the Texas Water Development Board, described and characterized examples of geomorphic units within the channels and alluvial valleys of Texas Gulf Coastal Plain rivers using a geomorphic unit classification scale that differentiates geomorphic units on the basis of their location either outside or inside the river channel. The geomorphic properties of a river system determine the distribution and type of potential habitat both within and adjacent to the channel. This report characterizes the geomorphic units contained in the river channels and alluvial valleys of Texas Gulf Coastal Plain rivers in the context of the River Styles framework. This report is intended to help Texas Instream Flow Program practitioners, river managers, ecologists and biologists, and others interested in the geomorphology and the physical processes of the rivers of the Texas Gulf Coastal Plain (1) gain insights into how geomorphic units develop and adjust spatially and temporally, and (2) be able to recognize common geomorphic units from the examples cataloged in this report. Recent aerial imagery (high-resolution digital orthoimagery) collected in 2008 and 2009 were inspected by using geographic information system software to identify representative examples of the types of geomorphic units that occurred in the study area. Geomorphic units outside the channels of Texas Gulf Coastal Plain rivers are called \\"valley geomorphic units\\" in this report. Valley geomorphic units for the Texas Gulf Coastal Plain rivers described in this report are terraces, flood plains, crevasses and crevasse splays, flood-plain depressions, tie channels, tributaries, paleochannels, anabranches, distributaries, natural levees, neck cutoffs, oxbow lakes, and constructed channels. Channel geomorphic units occur in the river channel and are subject to frequent stresses associated with flowing water and sediment transport; they adjust (change) relatively quickly in

  4. Nutrient contributions to the Santa Barbara Channel, California, from the ephemeral Santa Clara River

    Science.gov (United States)

    Warrick, J.A.; Washburn, L.; Brzezinski, Mark A.; Siegel, D.A.

    2005-01-01

    The Santa Clara River delivers nutrient rich runoff to the eastern Santa Barbara Channel during brief (???1-3 day) episodic events. Using both river and oceanographic measurements, we evaluate river loading and dispersal of dissolved macronutrients (silicate, inorganic N and P) and comment on the biological implications of these nutrient contributions. Both river and ocean observations suggest that river nutrient concentrations are inversely related to river flow rates. Land use is suggested to influence these concentrations, since runoff from a subwatershed with substantial agriculture and urban areas had much higher nitrate than runoff from a wooded subwatershed. During runoff events, river nutrients were observed to conservatively mix into the buoyant, surface plume immediately seaward of the Santa Clara River mouth. Dispersal of these river nutrients extended 10s of km into the channel. Growth of phytoplankton and nutrient uptake was low during our observations (1-3 days following runoff), presumably due to the very low light levels resulting from high turbidity. However, nutrient quality of runoff (Si:N:P = 16:5:1) was found to be significantly different than upwelling inputs (13:10:1), which may influence different algal responses once sediments settle. Evaluation of total river nitrate loads suggests that most of the annual river nutrient fluxes to the ocean occur during the brief winter flooding events. Wet winters (such as El Nin??o) contribute nutrients at rates approximately an order-of-magnitude greater than "average" winters. Although total river nitrate delivery is considerably less than that supplied by upwelling, the timing and location of these types of events are very different, with river discharge (upwelling) occurring predominantly in the winter (summer) and in the eastern (western) channel. ?? 2004 Elsevier Ltd. All rights reserved.

  5. Spatial and temporal variability in sedimentation rates associated with cutoff channel infill deposits: Ain River, France

    Science.gov (United States)

    Piegay, H.; Hupp, C.R.; Citterio, A.; Dufour, S.; Moulin, B.; Walling, D.E.

    2008-01-01

    Floodplain development is associated with lateral accretion along stable channel geometry. Along shifting rivers, the floodplain sedimentation is more complex because of changes in channel position but also cutoff channel presence, which exhibit specific overflow patterns. In this contribution, the spatial and temporal variability of sedimentation rates in cutoff channel infill deposits is related to channel changes of a shifting gravel bed river (Ain River, France). The sedimentation rates estimated from dendrogeomorphic analysis are compared between and within 14 cutoff channel infills. Detailed analyses along a single channel infill are performed to assess changes in the sedimentation rates through time by analyzing activity profiles of the fallout radionuclides 137Cs and unsupported 210Pb. Sedimentation rates are also compared within the channel infills with rates in other plots located in the adjacent floodplain. Sedimentation rates range between 0.65 and 2.4 cm a -1 over a period of 10 to 40 years. The data provide additional information on the role of distance from the bank, overbank flow frequency, and channel geometry in controlling the sedimentation rate. Channel infills, lower than adjacent floodplains, exhibit higher sedimentation rates and convey overbank sediment farther away within the floodplain. Additionally, channel degradation, aggradation, and bank erosion, which reduce or increase the distance between the main channel and the cutoff channel aquatic zone, affect local overbank flow magnitude and frequency and therefore sedimentation rates, thereby creating a complex mosaic of sedimentation zones within the floodplain and along the cutoff channel infills. Last, the dendrogeomorphic and 137Cs approaches are cross validated for estimating the sedimentation rate within a channel infill. Copyright 2008 by the American Geophysical Union.

  6. 33 CFR 162.35 - Channel of Christina River, Del.; navigation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Channel of Christina River, Del.; navigation. 162.35 Section 162.35 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY INLAND WATERWAYS NAVIGATION REGULATIONS § 162.35 Channel...

  7. Quantifying River Channel Stability at the Basin Scale

    Directory of Open Access Journals (Sweden)

    Philip J. Soar

    2017-02-01

    Full Text Available This paper examines the feasibility of a basin‐scale scheme for characterising and quantifying river reaches in terms of their geomorphological stability status and potential for morphological adjustment based on auditing stream energy. A River Energy Audit Scheme (REAS is explored, which involves integrating stream power with flow duration to investigate the downstream distribution of Annual Geomorphic Energy (AGE. This measure represents the average annual energy available with which to perform geomorphological work in reshaping the channel boundary. Changes in AGE between successive reaches might indicate whether adjustments are likely to be led by erosion or deposition at the channel perimeter. A case study of the River Kent in Cumbria, UK, demonstrates that basin‐wide application is achievable without excessive field work and data processing. However, in addressing the basin scale, the research found that this is inevitably at the cost of a number of assumptions and limitations, which are discussed herein. Technological advances in remotely sensed data capture, developments in image processing and emerging GIS tools provide the near‐term prospect of fully quantifying river channel stability at the basin scale, although as yet not fully realized. Potential applications of this type of approach include system‐wide assessment of river channel stability and sensitivity to land‐use or climate change, and informing strategic planning for river channel and flood risk management.

  8. Statistical Characterization of River and Channel Network Formation in Intermittently Flowing Vortex Systems.

    Science.gov (United States)

    Olson, C. J.; Reichhardt, C.; Nori, F.

    1997-03-01

    Vortices moving in dirty superconductors can form intricate flow patterns, resembling fluid rivers, as they interact with the pinning landscape (F. Nori, Science 271), 1373 (1996).. Weaker pinning produces relatively straight nori>vortex channels, while stronger pinning results in the formation of one or more winding channels that carry all flow. This corresponds to a crossover from elastic flow to plastic flow as the pinning strength is increased. For several pinning parameters, we find the fractal dimension of the channels that form, the vortex trail density, the distance travelled by vortices as they pass through the sample, the branching ratio, the sinuosity, and the size distribution of the rivers, and we compare our rivers with physical rivers that follow Horton's laws.

  9. Channel adjustements over the last century of the Moldova River, Romania

    Science.gov (United States)

    Chiriloaei, F. A.; Radoane, M.; Radoane, N.

    2012-04-01

    Moldova River is a 205 km long river, right tributary of the Siret River, with the confluence close to Roman city. The most important tributaries are Moldoviţa, Suha Mică, Suha Mare, Râsca, Ozana and Topolita Rivers. The drainage basin area is 4316 km2, a discharge of about 32.8 m3/s and is superimposed on four lithostratigraphic units: the crystalline Mesozoic unit, the flysch unit, the molasse unit and the platform unit. The study reach is 110 km long and is located on the external part of the Eastern-Carpathians at the contact with the Moldavian Plateau. This contact is characterised by a piedmont zone. The high rate of alluviation in this piedmont plain had a decisive role on the spatial and temporal evolution of fluvial forms and processes, expressed in the morphology of alluvial terraces in the valley bottom, the morphology of the active channel, the spatial distribution of bars and secondary channels and lateral migration rates. The morphology of the river in the study reach is dominated by braided and wandering channel patterns. The present (2005) active channel width ranges between 700 and 1000 m. Planform changes of river features over the last 100 years were analyzed on three historical maps (1910, 1960, and 1980) and one orthophoto (2005). Channel width average has significantly decreased in the last century. The Moldova river channel width suffered a strong narrowing, approximately 76% (from 1910 to 2005). So, from a channel width about more than 1200 m, it decreased at about 300 m. We can note two phase of narrowing: a first one - stronger, of 56%, untill 1960 (a reduction of active channel width for about 10.5 m/year) and a second phase, of 35%, after 1960, with a narrowing rate for about 8.8 m/an. The historical trend of braiding index shows a remarkable decrease in the last 50 - 60 years, from 3.2 in 1960, at 2.6 in 1980 and 2.0, in 2005, for all the extra-Carpathian study reach (110 km). There are different situations at local scale, shown

  10. Modeling the Effects of Connecting Side Channels to the Long Tom River, Oregon

    Science.gov (United States)

    Appleby, C.; McDowell, P. F.

    2015-12-01

    The lower Long Tom River is a heavily managed, highly modified stream in the southwestern Willamette Valley with many opportunities for habitat improvements and river restoration. In the 1940s and 1950s, the US Army Corps of Engineers dramatically altered this river system by constructing the Fern Ridge Dam and three, large drop structures, converting the River from a highly sinuous channel to a straight, channelized stream that is interrupted by these grade control structures, and removed the majority of the riparian vegetation. As a result, juvenile spring Chinook salmon are no longer found in the Watershed and the local population of coastal cutthroat trout face limited aquatic habitat. When the river was channelized, long sections of the historical channel were left abandoned on the floodplain. Reconnecting these historical channels as side channels may improve the quality and quantity of aquatic habitat and could allow fish passage around current barriers. However, such construction may also lead to undesirable threats to infrastructure and farmland. This study uses multiple HEC-RAS models to determine the impact of reconnecting two historical channels to the lower Long Tom River by quantifying the change in area of flood inundation and identifying infrastructure in jeapordy given current and post-restoration conditions for 1.5, 5, 10, and 25-year flood discharges. Bathymetric data from ADCP and RTK-GPS surveys has been combined with LiDAR-derived topographic data to create continuous elevation models. Several types of side channel connections are modeled in order to determine which type of connection will result in both the greatest quantity of accessible habitat and the fewest threats to public and private property. In the future, this study will also consider the change in the quantity of physical salmonid habitat and map the areas prone to sedimentation and erosion using CEASAR and PHABSIM tools.

  11. Spatiotemporal variations in channel changes caused by cumulative factors in a meandering river: The lower Peixe River, Brazil

    Science.gov (United States)

    Morais, Eduardo S.; Rocha, Paulo C.; Hooke, Janet

    2016-11-01

    Channel changes in meandering rivers naturally exhibit complex behaviour, and understanding the river dynamics can be challenging in environments also subject to cumulative human impacts. Planform changes were analysed on four reaches of the lower course of the Peixe River, Brazil, at decadal scales over the period 1962-2008 from aerial photographs and satellite imagery, complemented by a historical map from 1907. Analysis of the spatial and temporal patterns of channel change mechanisms and morphometry of bends and of the sinuosity and morphodynamic variations of the reaches demonstrates major changes in planform characteristics. Sinuosity in all reaches decreased from 2.6 to 1.7, average wavelength of bends has increased from 200 to 500 m, and the planform has become much simpler. Changes have been progressive from downstream to upstream, with higher intensities of processes, particularly cutoffs first in downstream reaches then more recently in upstream reaches. It is suggested that channel changes represent a morphological adjustment to human interventions, such as reservoir construction and land use. However, evidence of the autogenic behaviour of meanders is highlighted in which the existence of compound meanders reveals control over the spatial variation in the reaches. The results suggest that geomorphic thresholds associated with the compound meander formation and the bend evolution should be considered, even in impacted meandering rivers, because they exert primary controls on the spatial-temporal adjustment of channels.

  12. Residence Times of Juvenile Salmon and Steelhead in Off-Channel Tidal Freshwater Habitats, Columbia River, USA

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Gary E.; Ploskey, Gene R.; Sather, Nichole K.; Teel, D. J.

    2015-05-01

    We estimated seasonal residence times of acoustic-tagged juvenile salmonids in off-channel, tidal freshwater habitats of the Columbia River near the Sandy River delta (rkm 198; 2007, 2008, 2010, and 2011) and Cottonwood Island (rkm 112; 2012).

  13. Preliminary Skylab MSS channel evaluation. [Susquehanna river basin

    Science.gov (United States)

    Mcmurtry, G. J.; Petersen, G. W. (Principal Investigator); Barr, D. M.; Borden, F. Y.

    1975-01-01

    The author has identified the following significant results. A set of 18 channels which were considered of usable quality were identified. These were channels 1-14, 17, 19-21. Channels 15, 16, 18, and 22 were dropped out because they were of poor quality; channels 7 and 11 were dropped to limit the total channel number to 16. From these 16 channels, a total of 22 signatures were obtained. Eight were developed from uniform blocks of the UMAP, and 14 from use of the DCLUS program. These signatures fell into six basic categories and classified more than 90% of the five scenes mapped: agriculture land (6 signatures); forest aland (4); water (2); open nonagriculture land (2); urban (6); and disturbed land (2).

  14. Wildlife use of back channels associated with islands on the Ohio River

    Science.gov (United States)

    Zadnik, A.K.; Anderson, James T.; Wood, P.B.; Bledsoe, K.

    2009-01-01

    The back channels of islands on the Ohio River are assumed to provide habitat critical for several wildlife species. However, quantitative information on the wildlife value of back channels is needed by natural resource managers for the conservation of these forested islands and embayments in the face of increasing shoreline development and recreational boating. We compared the relative abundance of waterbirds, turtles, anurans, and riparian furbearing mammals during 2001 and 2002 in back and main channels of the Ohio River in West Virginia. Wood ducks (Aix sponsa), snapping turtles (Chelydra serpentina), beavers (Castor canadensis), and muskrats (Ondatra zibethicus) were more abundant in back than main channels. Spring peepers (Pseudacris crucifer) and American toads (Bufo americanus) occurred more frequently on back than main channels. These results provide quantitative evidence that back channels are important for several wildlife species. The narrowness of the back channels, the protection they provide from the main current of the river, and their ability to support vegetated shorelines and woody debris, are characteristics that appear to benefit these species. As a conservation measure for important riparian wildlife habitat, we suggest limiting building of piers and development of the shoreline in back channel areas. ?? 2009, The Society of Wetland Scientists.

  15. Channel morphology and its impact on flood passage, the Tianjiazhen reach of the middle Yangtze River

    Science.gov (United States)

    Shi, Yafeng; Zhang, Qiang; Chen, Zhongyuan; Jiang, Tong; Wu, Jinglu

    2007-03-01

    The Tianjiazhen reach of the middle Yangtze is about 8 km long, and characterized by a narrow river width of 650 m and local water depth of > 90 m in deep inner troughs, of which about 60 m is below the mean sea level. The troughs in the channel of such a large river are associated with regional tectonics and local lithology. The channel configuration plays a critical role in modifying the height and duration of river floods and erosion of the riverbed. The formation of the troughs in the bed of the Yangtze is considered to be controlled by sets of NW-SE-oriented neotectonic fault zones, in which some segments consist of highly folded thick Triassic limestone crossed by the Yangtze River. Several limestone hills, currently located next to the river channel, serve as nodes that create large vortices in the river, thereby accelerating downcutting on the riverbed composed of limestone highly susceptible to physical corrosion and chemical dissolution. Hydrological records indicate that the nodal hills and channel configuration at Tianjiazhen do not impact on normal flow discharges but discharges > 50,000 m 3s - 1 are slowed down for 2-3 days. Catastrophic floods are held up for even longer periods. These inevitably result in elevated flood stages upstream of prolonged duration, affecting large cities such as Wuhan and a very large number of people.

  16. Large flood on a mountain river subjected to restoration: effects on aquatic habitats, channel morphology and valley infrastructure

    Science.gov (United States)

    Hajdukiewicz, Hanna; Wyżga, Bartłomiej; Mikuś, Paweł; Zawiejska, Joanna; Radecki-Pawlik, Artur

    2016-04-01

    The Biała River, Polish Carpathians, was considerably modified by channelization and channel incision in the twentieth century. To restore the Biała, establishing an erodible corridor was proposed in two river sections located in its mountain and foothill course. In these sections, longer, unmanaged channel reaches alternate with short, channelized reaches; and channel narrowing and incision increases in the downstream direction. In June 2010 an 80-year flood occurred on the river; and this study aims at determining its effects on physical habitat conditions for river biota, channel morphology, and valley-floor infrastructure. Surveys of 10 pairs of closely located, unmanaged and channelized cross sections, performed in 2009 and in the late summer 2010, allowed us to assess the flood-induced changes to physical habitat conditions. A comparison of channel planforms determined before (2009) and after (2012) the flood provided information on the degree of channel widening as well as changes in the width of particular elements of the river's active zone in eight stretches of the Biała. The impact of the flood on valley-floor infrastructure was confronted with the degree of river widening in unmanaged and channelized river reaches. Before the flood, unmanaged cross sections were typified by finer bed material and greater lateral variability in depth-averaged and near-bed flow velocity than channelized cross sections. The flood tended to equalize habitat conditions in both types of river cross sections, obliterating differences (in particular physical habitat parameters) between channelized and unmanaged channel reaches. River widening mostly reflected an increase in the area of channel bars, whereas the widening of low-flow channels was less pronounced. A comparison of channel planform from 2009 and 2012 indicated that intense channel incision typical of downstream sections limited river widening by the flood. Active channel width increased by half in the unmanaged

  17. Channel centerline for the Nehalem River, Oregon in 1967

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  18. Channel centerline for the Nehalem River, Oregon in 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  19. Channel centerline for the Nehalem River, Oregon in 1939

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  20. Channel centerline for the Coquille River, Oregon in 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Coquille River system is an unregulated system that encompasses 2,745 square kilometers of southwestern Oregon and flows into the Pacific Ocean near the town of...

  1. Channel centerline for the Coquille River, Oregon in 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Coquille River system is an unregulated system that encompasses 2,745 square kilometers of southwestern Oregon and flows into the Pacific Ocean near the town of...

  2. Channel centerline for the Coquille River, Oregon in 1967

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Coquille River system is an unregulated system that encompasses 2,745 square kilometers of southwestern Oregon and flows into the Pacific Ocean near the town of...

  3. Channel centerline for the Coquille River, Oregon in 1939

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Coquille River system is an unregulated system that encompasses 2,745 square kilometers of southwestern Oregon and flows into the Pacific Ocean near the town of...

  4. Channel centerline for the Nehalem River, Oregon in 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  5. ADCP measured flow current of the middle-lower Changjiang River channel

    Institute of Scientific and Technical Information of China (English)

    Qiang ZHANG; Yafeng SHI; Zhongyuan CHEN; Tong JIANG

    2008-01-01

    The water column flow velocity of 36 river sections in the river reach between Hankou (Wuhan) and Wuxue of the middle-lower Changjiang River.Their cross sectional distribution patterns in relation to the river channel morphologies were examined by using shipmounted ADCP (Acoustic Doppler Current Profiler) instrument.The results indicate four (Ⅰ-Ⅳ) types of river channel morphology associated flow patterns:Ⅰ-laterally deepening riverbed topographic pattern; Ⅱ-symmetrical to asymmetrical riverbed topographic pattern; Ⅲ-relative fiat riverbed topographic pattern,and Ⅳ-sandbar supported riverbed topographic pattern.All these correspond to the different patterns of flow velocity distribution.The maximum flow velocity is usually related to the deeper water depth,but irregular water column distribution of flow current velocity results often from the vortices' current associated with river knots.Deeper river water depth is usually identified in the river reach located slightly downstream to the river knot,where faster flow velocity occurs.Downward change in flow velocity fits semi-log law,showing an exponential decreasing flow current with the maximum flow velocity near the water surface.However,in the river reach near the river knots,the water column distribution of flow current velocity does not fit the semi-log law,showing the irregular flow current pattern.This study,in context of river catchment management,highlights the controls of riverbed morphology to the flow current structure,which will shed light on the post study of Three Gorges damming in 2009.

  6. Differences between main-channel and off-channel food webs in the upper Mississippi River revealed by fatty acid profiles of consumers

    Science.gov (United States)

    Larson, James H.; Bartsch, Michelle; Gutreuter, Steve; Knights, Brent C.; Bartsch, Lynn; Richardson, William B.; Vallazza, Jonathan M.; Arts, Michael T.

    2015-01-01

    Large river systems are often thought to contain a mosaic of patches with different habitat characteristics driven by differences in flow and mixing environments. Off-channel habitats (e.g., backwater areas, secondary channels) can become semi-isolated from main-channel water inputs, leading to the development of distinct biogeochemical environments. Observations of adult bluegill (Lepomis macrochirus) in the main channel of the Mississippi River led to speculation that the main channel offered superior food resources relative to off-channel areas. One important aspect of food quality is the quantity and composition of polyunsaturated fatty acids (PUFA). We sampled consumers from main-channel and backwater habitats to determine whether they differed in PUFA content. Main-channel individuals for relatively immobile species (young-of-year bluegill, zebra mussels [Dreissena polymorpha], and plain pocketbook mussels [Lampsilis cardium]) had significantly greater PUFA content than off-channel individuals. No difference in PUFA was observed for the more mobile gizzard shad (Dorsoma cepedianum), which may move between main-channel and off-channel habitats even at early life-history stages. As off-channel habitats become isolated from main-channel waters, flow and water column nitrogen decrease, potentially improving conditions for nitrogen-fixing cyanobacteria and vascular plants that, in turn, have low PUFA content. We conclude that main-channel food webs of the upper Mississippi River provide higher quality food resources for some riverine consumers as compared to food webs in off-channel habitats.

  7. Impact of river-tide dynamics on the residual water level slope and residual sediment transport in the Pearl River channel networks

    Science.gov (United States)

    Cai, Huayang; Zhang, Zihao; Yang, Qingshu; Ou, Suying

    2016-04-01

    Large-scale delta systems, such as the Rhine-Meuse delta, the Mississippi River delta, the Mekong delta, the Yangtze delta and the Pearl River delta etc., usually feature a typical channel networks, where individual channels are interrelated through a networks system, resulting in both longitudinal and transverse variations of residual water level slope (averaged over a lunar day) caused by the river-tide interplay. Enhancing our insight of river-tide dynamics in these channel networks has vital importance for the protection and management of estuarine environment since river-tide interplay is closely related to sediment transport, water quality, water utilization and estuarine ecosystem. In this study, we investigate the impact of river-tide dynamics on the temporal-spatial changes of flow and suspended sediment load in terms of residual water level slope and residual sediment transport in the Pearl River channel networks, which is one of the complex channel networks in the world. Making use of a nonstationary harmonic analysis (NS_TIDE), the continuous time series observations of velocity covering a spring-neap cycle in 1999 (representing flood season) and 2001 (representing dry season) collected from around 60 stations in the Pearl River channel networks have been used to extract the temporal-spatial changes in residual velocity and tidal properties (including amplitudes and phases) as a function of variable river flow debouching into the delta. On the basis of harmonic analysis, the tidally averaged friction is decomposed into contributions made by riverine forcing alone, river-tide interaction and tidal asymmetry using Chebyshev polynomials approach. It is shown that river flow enhances friction via river-tide interaction, which increases the residual water level slope that influences the distribution of suspended sediment load in the Pearl River channel networks.

  8. Large-scale dam removal on the Elwha River, Washington, USA: river channel and floodplain geomorphic change

    Science.gov (United States)

    East, Amy E.; Pess, George R.; Bountry, Jennifer A.; Magirl, Christopher S.; Ritchie, Andrew C.; Logan, Joshua; Randle, Timothy J.; Mastin, Mark C.; Minear, Justin T.; Duda, Jeffrey J.; Liermann, Martin C.; McHenry, Michael L.; Beechie, Timothy J.; Shafroth, Patrick B.

    2015-01-01

    A substantial increase in fluvial sediment supply relative to transport capacity causes complex, large-magnitude changes in river and floodplain morphology downstream. Although sedimentary and geomorphic responses to sediment pulses are a fundamental part of landscape evolution, few opportunities exist to quantify those processes over field scales. We investigated the downstream effects of sediment released during the largest dam removal in history, on the Elwha River, Washington, USA, by measuring changes in riverbed elevation and topography, bed sediment grain size, and channel planform as two dams were removed in stages over two years.

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

    Science.gov (United States)

    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.

  10. Yampa River channel elevation at Deerlodge Park, CO

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S Geological Survey Scientific Investigations Map provides raster data that can be used to assess channel response to streamflow alteration scenarios indicated...

  11. Effects of environmental changes and human impact on the functioning of mountain river channels, Carpathians, southern Poland

    Directory of Open Access Journals (Sweden)

    Krzemień Kazimierz

    2015-09-01

    Full Text Available In the northern slope of the Carpathian Mountains and in their foreland, river and stream channels have been significantly transformed by human impact. These transformations result from changing land use in river basins and direct interference with river channels (alluvia extraction, engineering infrastructure, channel straightening. Anthropogenic impacts cause significant changes in the channel system patterns leading to increased impact of erosion. This mainly leads to the channelling of the fluvial system. This article reviews studies of structure and dynamics of Carpathian river channels conducted based on the methodology of collection of data on channel systems, developed in the Department of Geomorphology of the Institute of Geography and Spatial Management, Jagiellonian University.

  12. Braiding of submarine channels controlled by aspect ratio similar to rivers

    Science.gov (United States)

    Foreman, Brady Z.; Lai, Steven Y. J.; Komatsu, Yuhei; Paola, Chris

    2015-09-01

    The great majority of submarine channels formed by turbidity and density currents are meandering in planform; they consist of a single, sinuous channel that transports a turbid, dense flow of sediment from submarine canyons to ocean floor environments. Braided turbidite systems consisting of multiple, interconnected channel threads are conspicuously rare. Furthermore, such systems may not represent the spontaneous planform instability of true braiding, but instead result from erosive processes or bathymetric variability. In marked contrast to submarine environments, both meandering and braided planforms are common in fluvial systems. Here we present experiments of subaqueous channel formation conducted at two laboratory facilities. We find that density currents readily produce a braided planform for flow aspect ratios of depth to width that are similar to those that produce river braiding. Moreover, we find that stability model theory for river planform morphology successfully describes submarine channels in both experiments and the field. On the basis of these observations, we propose that the rarity of braided submarine channels is explained by the generally greater flow depths in submarine systems, which necessitate commensurately greater widths to achieve the required aspect ratio, along with feedbacks among flow thickness, suspended sediment concentration and channel relief that induce greater levee deposition rates and limit channel widening.

  13. The formation and maintenance of single-thread tie channels entering floodplain lakes: observations from three diverse river systems

    Energy Technology Data Exchange (ETDEWEB)

    Rowland, Joel C [Los Alamos National Laboratory; Dietrich, William E [UC BERKELEY; Day, Geoff [NEWCREST MINING; Parker, Gary [UNIV OF ILLINOIS

    2009-01-01

    Tie channels connect rivers to floodplain lakes on many lowland rivers and thereby play a central role in floodplain sedimentology and ecology, yet they are generally unrecognized and little studied. here we report the results of field studies focused on tie channel origin and morphodynamics in three contrasting systems: the Middle Fly River, Papua New Guinea, the Lower Mississippi River, and Birch Creek in Alaska. Across these river systems, tie channels vary by an order of magnitude in size but exhibit the same characteristic morphology and appear to develop and evolve by a similar set of processes. In all three systems, the channels are characterized by a narrow, leveed single-thread morphology with maximum width approximately one tenth the width of the mainstem river. The channels typically have a V shaped cross-section, unlike most fluvial channels. These channels develop as lakes become isolated from the river by sedimentation. Narrowing of the connection between river and lake causes a sediment-laden jet to develop. Levees develop along the margins of the jet leading to channel emergence and eventual levee aggradation to the height of the mainstem levees. Bi-directional flow in these channels is common. Outflows from the lake scour sediment and prevent channel blockage. We propose that channel geometry and size are then controlled by a dynamic balance between channel narrowing by suspended sediment deposition and incision and widening by mass failure of banks during outflows. Tie channels are laterally stable and may convey flow for hundreds to a few thousand of years.

  14. Man-made secondary channels along the river Rhine (The Netherlands); results of post-project monitoring

    NARCIS (Netherlands)

    Simons, J.H.E.J.; Bakker, C.; Schropp, M.H.I.; Jans, L.H.; Kok, F.R.; Grift, R.E.

    2001-01-01

    Owing to river regulation in the past and intensive farming, the ecological value of the floodplains of the River Rhine in The Netherlands has decreased dramatically. One way to restore riverine biotopes is to create permanently flowing channels in the floodplain. Along the River Waal, the main

  15. Evolution of channel morphology in a large river subject to rectification

    Science.gov (United States)

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

    2016-04-01

    Many large rivers in Europe have been subject to heavy modifications for land reclamation and flood mitigation through centuries. As a consequence, the study of the pre-alteration morphological patterns and of the related channel evolution following the anthropic modifications is rather challenging. The Adige River is the second longest river in Italy and drains 12,100 km2 of the Eastern Italian Alps. Currently, it features a straight to sinuous pattern and an average channel width of 40-60 m. A massive rectification scheme aiming at land reclamation of the Adige valley bottom was planned in the late 18th century, and implemented starting in the first decades of 19th century. Nowadays, it can be considered one of the most altered rivers in Italy, not only due to channelization but also to the presence of many hydropower reservoirs and check-dams along its tributaries. This study aims to the reconstruction of the Adige River's evolutionary trajectory over the last 250 years, and comprehension of key control factors driving channel evolution. A multi-temporal analysis of historical maps and orthophotos from 1776, to 2006 was performed in order to assess channel modifications. In addition, land use changes at the basin scale, years of occurrence of most relevant flood events, and climate variability over the investigated period were analyzed. The detailed topographical map surveyed in 1803 was taken as a reference, and the study sector (115 km long) was divided into 39 reaches. Active channel, bars, riparian vegetation and channel control works were geo-processed. Results show that the Adige River suffered the most intense alteration from 1803 to 1855, and especially from 1847 to 1855. During this period channel narrowing ranged from 14% to 70%, coupled with pattern changes and decreases in the braiding, sinuosity and anabrancing indices. Most important alterations occurred in the reaches presenting a multi-thread morphology in 1803, as their average width declined

  16. A comparison of the channel geomorphic unit composition of regulated and unregulated reaches in the Soča river:

    OpenAIRE

    Hill, Graham; Maddock, Ian P.; Smolar-Žvanut, Nataša

    2007-01-01

    This paper examines the effects of flow regulation on the size, spatial distribution and connectivity of channel geomorphic units (CGU) in the Soča River, Slovenia. A river channel survey was completed along three reaches, i.e. an unregulated reach (reach 1), and two regulated reaches with lower discharges, (reach 2 and 3). Results demonstrated significant differences in the CGU composition between the unregulated and regulated reaches. Flow regulation in the Soča River alters the dominant ty...

  17. 75 FR 20776 - Security Zone; Potomac River, Washington Channel, Washington, DC

    Science.gov (United States)

    2010-04-21

    ..., Washington, DC AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is... Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and... (NPRM) entitled ``Security Zone; Potomac River, Washington Channel, Washington, DC'' in the...

  18. Avulsions, channel evolution and floodplain sedimentation rates of the anastomosing upper Columbia River, British Columbia, Canada

    NARCIS (Netherlands)

    Makaske, B.; Smith, D.G.; Berendsen, H.J.A.

    2002-01-01

    Ages of channels of the anastomosing upper Columbia River, south-eastern British Columbia, Canada, were investigated in a cross-valley transect by C-14 dating of subsurface floodplain organic material from beneath levees. The avulsion history within the transect was deduced from these data, and morp

  19. 77 FR 3118 - Security Zone; Choptank River and Cambridge Channel, Cambridge, MD

    Science.gov (United States)

    2012-01-23

    ... 3118-3121] [FR Doc No: 2012-1172] DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 165 [Docket No. USCG-2011-1164] RIN 1625-AA87 Security Zone; Choptank River and Cambridge Channel, Cambridge, MD..., U.S. Coast Guard, Captain of the Port Baltimore. [FR Doc. 2012-1172 Filed 1-20-12; 8:45 am]...

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

    Science.gov (United States)

    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

  1. Plan form changes of Gumara River channel over 50 years (Upper Blue Nile basin, Ethiopia)

    Science.gov (United States)

    Abate, Mengiste; Nyssen, Jan; Mehari, Michael

    2014-05-01

    Channel plan form changes were investigated along the 65 km long Gumara River in Lake Tana basin (Ethiopia) by overlaying information from aerial photographs and SPOT imagery. Two sets of aerial photographs (1957 and 1980) were scanned, and then orthorectified in ENVI 4.2 environment. Recent channel plan form information was extracted from SPOT images of 2006. ERDAS 2010 and ArcGIS 10.1 tools were used for the data preparation and analysis. The information on river plan form changes spans from 1957 to 2006 (49 years), during which time the Gumara catchment has been subjected to changes in land use/cover and increasing water abstraction, which may have affected its hydrogeomorphology. The results indicated that the lower reach of Gumara at its mouth has undergone major plan form changes. A delta of 1.12 km² was created between 1957 and 1980 and additional 1.00 km² land has been created between 1980 and 2006. The sinuosity of the plan form changed only slightly through the study period: 1.78 in 1957, 1.76 in 1980, and 1.81 in 2006. Comparison of cross sections at the hydrological gauging station showed that the river bed aggraded in the order of 1.5 m to 2.5 m for the period 1963-2009. The trend analysis of stream flow of Gumara River versus rainfall in the catchment also indicated that the bed level of the Gumara river at its gauging station has risen. From field observations, the impact of direct human interventions was identified. The building of artificial levees along the river banks has contributed to huge deposition in the river bed. At locations where intensive irrigation takes place in the floodplain, seepage water through the banks created river bank failure and modifications in plan form. The unstable segments of the river reach were identified and will be further analysed.

  2. Suspended sediment dynamics in a tidal channel network under peak river flow

    Science.gov (United States)

    Achete, Fernanda Minikowski; van der Wegen, Mick; Roelvink, Dano; Jaffe, Bruce

    2016-05-01

    Peak river flows transport fine sediment, nutrients, and contaminants that may deposit in the estuary. This study explores the importance of peak river flows on sediment dynamics with special emphasis on channel network configurations. The Sacramento-San Joaquin Delta, which is connected to San Francisco Bay (California, USA), motivates this study and is used as a validation case. Besides data analysis of observations, we applied a calibrated process-based model (D-Flow FM) to explore and analyze high-resolution (˜100 m, ˜1 h) dynamics. Peak river flows supply the vast majority of sediment into the system. Data analysis of six peak flows (between 2012 and 2014) shows that on average, 40 % of the input sediment in the system is trapped and that trapping efficiency depends on timing and magnitude of river flows. The model has 90 % accuracy reproducing these trapping efficiencies. Modeled deposition patterns develop as the result of peak river flows after which, during low river flow conditions, tidal currents are not able to significantly redistribute deposited sediment. Deposition is quite local and mainly takes place at a deep junction. Tidal movement is important for sediment resuspension, but river induced, tide residual currents are responsible for redistributing the sediment towards the river banks and to the bay. We applied the same forcing for four different channel configurations ranging from a full delta network to a schematization of the main river. A higher degree of network schematization leads to higher peak-sediment export downstream to the bay. However, the area of sedimentation is similar for all the configurations because it is mostly driven by geometry and bathymetry.

  3. Applying fluvial geomorphology to river channel management: Background for progress towards a palaeohydrology protocol

    Science.gov (United States)

    Gregory, K. J.; Benito, G.; Downs, P. W.

    2008-06-01

    Significant developments have been achieved in applicable and applied fluvial geomorphology as shown in publications of the last three decades, analyzed as the basis for using results of studies of environmental change as a basis for management. The range of types of publications and of activities are more pertinent to river channel management as a result of concern with sustainability, global climate change, environmental ethics, ecosystem health concepts and public participation. Possible applications, with particular reference to river channel changes, include those concerned with form and process, assessment of channel change, urbanization, channelization, extractive industries, impact of engineering works, historical changes in land use, and restoration with specific examples illustrated in Table 1. In order to achieve general significance for fluvial geomorphology, more theory and extension by modelling methods is needed, and examples related to morphology and process characteristics, integrated approaches, and changes of the fluvial system are collected in Table 2. The ways in which potential applications are communicated to decision-makers range from applicable outputs including publications ranging from review papers, book chapters, and books, to applied outputs which include interdisciplinary problem solving, educational outreach, and direct involvement, with examples summarized in Table 3. On the basis of results gained from investigations covering periods longer than continuous records, a protocol embracing palaeohydrological inputs for application to river channel management is illustrated and developed as a synopsis version (Table 4), demonstrating how conclusions from geomorphological research can be expressed in a format which can be considered by managers.

  4. Pike Esox Lucius Distribution and Feeding Comparisons in Natural and Historically Channelized River Sections

    Directory of Open Access Journals (Sweden)

    Ivanovs Kaspars

    2016-12-01

    Full Text Available During the last century a large portion of small and medium-sized rivers in Latvia were channelized, hydroelectric power stations were also built, which led to changes in the hydrodynamic conditions, geomorphological structure, as well as a change in the fish fauna. Fish are an integral part of any community in natural or man-made bodies of water. They actively participate in maintaining the system, balancing/equilibrium, energy, substance transformation and biomass production. They are able to influence other organisms in the ecosystem in which they live. The aim of the paper “Pike distribution and feeding comparisons in natural and historically channelized river sections” is to find out what pike feed on in different environments in Latvian rivers, such as natural and straightened river sections, as well as what main factors determine the composition of their food. Several points were assessed during the course of the study: the impact of environmental conditions on the feeding habits and the distribution of pike; the general feeding habits of predators in Latvian rivers; the feeding differences of predators in natural and straightened river sections; and lastly, rhithral and pothamal habitats were compared. The study was based on data from 2014 and 2015 on fish fauna monitoring. During the study, 347 pike were collected from 136 plots using electrofishing method.

  5. Pike Esox Lucius Distribution and Feeding Comparisons in Natural and Historically Channelized River Sections

    Science.gov (United States)

    Ivanovs, Kaspars

    2016-12-01

    During the last century a large portion of small and medium-sized rivers in Latvia were channelized, hydroelectric power stations were also built, which led to changes in the hydrodynamic conditions, geomorphological structure, as well as a change in the fish fauna. Fish are an integral part of any community in natural or man-made bodies of water. They actively participate in maintaining the system, balancing/equilibrium, energy, substance transformation and biomass production. They are able to influence other organisms in the ecosystem in which they live. The aim of the paper "Pike distribution and feeding comparisons in natural and historically channelized river sections" is to find out what pike feed on in different environments in Latvian rivers, such as natural and straightened river sections, as well as what main factors determine the composition of their food. Several points were assessed during the course of the study: the impact of environmental conditions on the feeding habits and the distribution of pike; the general feeding habits of predators in Latvian rivers; the feeding differences of predators in natural and straightened river sections; and lastly, rhithral and pothamal habitats were compared. The study was based on data from 2014 and 2015 on fish fauna monitoring. During the study, 347 pike were collected from 136 plots using electrofishing method.

  6. Elevated Channel Concavities Arising from Sediment-Flux Effects in Natural Rivers

    Science.gov (United States)

    Hobley, D. E. J.; Sinclair, H. D.; Gasparini, N. M.; Tucker, G. E.; Cowie, P. A.; Adams, J. M.; Hutton, E. W. H.; Istanbulluoglu, E.; Nudurupati, S. S.

    2014-12-01

    The concavity of an incising river system - a measure of the rate of change of its bed slope with increasing discharge downstream - is a commonly used metric in fluvial geomorphology. It is commonly used in assessing variation of factors such as uplift, climate, and rock type along a system in a qualitative way, and underpins a number of quantitative analyses in tectonic geomorphology, such as the normalized channel steepness index. However, the factors that fundamentally control channel concavities in rocky streams remain relatively poorly understood, especially in rivers that are undergoing transient response to a perturbation in their boundary conditions.Here we use a combination of field data and numerical modeling to demonstrate that elevated channel concavities are a common and shared response to the propagation of a convex-upward "knickzone" through a bedrock channel long profile. Simulations using the novel modeling framework Landlab exploring thresholded incision and saltation-abrasion theory indicate that the presence of the knickzone can perturb the relative sediment flux in the area immediately downstream of the convexity, allowing enhanced erosion there and systematic elevation of channel concavities in reaches downstream of this point. The reality of this effect is demonstrated using field and remotely sensed data from three sites - the Red River area, Yunnan, China; channels on the Ladakh batholith, Indian Himalaya; and the Fagaras Alps, Romania. All contain broad scale migrating knickzones, but the causes of the disturbances that produced them and scales of the systems differ. Nonetheless, the concavities of all the channels are all elevated in the same way downstream of knickzones, consistent with the modeling output. These results demonstrate the ubiquity of sediment flux effects on erosion rates in many natural channels, and have consequences for the way we read tectonic histories from landscapes.

  7. Channel change and bed-material transport in the Umpqua River basin, Oregon

    Science.gov (United States)

    Wallick, J. Rose; O'Connor, Jim E.; Anderson, Scott; Keith, Mackenzie K.; Cannon, Charles; Risley, John C.

    2011-01-01

    The Umpqua River drains 12,103 square kilometers of western Oregon; with headwaters in the Cascade Range, the river flows through portions of the Klamath Mountains and Oregon Coast Range before entering the Pacific Ocean. Above the head of tide, the Umpqua River, along with its major tributaries, the North and South Umpqua Rivers, flows on a mixed bedrock and alluvium bed, alternating between bedrock rapids and intermittent, shallow gravel bars composed of gravel to cobble-sized clasts. These bars have been a source of commercial aggregate since the mid-twentieth century. Below the head of tide, the Umpqua River contains large bars composed of mud and sand. Motivated by ongoing permitting and aquatic habitat concerns related to in-stream gravel mining on the fluvial reaches, this study evaluated spatial and temporal trends in channel change and bed-material transport for 350 kilometers of river channel along the Umpqua, North Umpqua, and South Umpqua Rivers. The assessment produced (1) detailed mapping of the active channel, using aerial photographs and repeat surveys, and (2) a quantitative estimation of bed-material flux that drew upon detailed measurements of particle size and lithology, equations of transport capacity, and a sediment yield analysis. Bed-material transport capacity estimates at 45 sites throughout the South Umpqua and main stem Umpqua Rivers for the period 1951-2008 result in wide-ranging transport capacity estimates, reflecting the difficulty of applying equations of bed-material transport to a supply-limited river. Median transport capacity values calculated from surface-based equations of bedload transport for each of the study reaches provide indications of maximum possible transport rates and range from 8,000 to 27,000 metric tons per year (tons/yr) for the South Umpqua River and 20,000 to 82,000 metric tons/yr for the main stem Umpqua River upstream of the head of tide; the North Umpqua River probably contributes little bed material. A

  8. Dynamic Channel Network Extraction from Satellite Imagery of the Jamuna River

    Science.gov (United States)

    Addink, E. A.; Marra, W. A.; Kleinhans, M. G.

    2010-12-01

    Evolution of the largest rivers on Earth is poorly understood while their response to global change is dramatic, such as severe drought and flooding problems. Rivers with high annual dynamics, like the Jamuna, allow us to study their response to changing conditions. Most remote-sensing work so far focused only on pixel-based analysis of channels and change detection or manual digitisation of channels, which is far from urgently needed quantifiers of pattern and pattern change. Using a series of Landsat TM images taken at irregular intervals showing inter- and intra-annual variation, we demonstrate that braided rivers can be represented as nearly chain-like directional networks. These can be studied with novel methods gleaned from neurology. These networks provide an integral spatial description of the network and should not be confused with hierarchical hydrological stream network descriptions developed in the ’60s to describe drainage basins. The images were first classified into water, bare sediment and vegetation. The contiguous water body of the river was then selected and translated into a network description with bifurcations and confluences at the nodes, and interconnecting channels. Along the entire river the well-known braiding indices were derived from the network. The channel width is a crucial attribute of the channel network as this allows the calculation of bifurcation asymmetry. The width was also used with channel length as weights to all the elements in the network in the calculation of more advanced measures for the nature and evolution of the channel network. The key step here is to describe river network evolution by identifying the same node in multiple subsequent images as well as new and abandoned nodes, in order to distinguish migration of bifurcations from avulsion processes. Once identified through time, the changes in node position and the changes in the connected channels can be quantified. These changes can potentially be linked to

  9. Morphodynamic river processes and techniques for assessment of channel evolution in Alpine gravel bed rivers

    Science.gov (United States)

    Formann, E.; Habersack, H. M.; Schober, St.

    2007-10-01

    Over the past 10 years many restoration projects have been undertaken in Austria, and river engineering measures such as spur dykes and longitudinal bank protection, which imposed fixed lateral boundaries on rivers, have been removed. The EU-Life Project "Auenverbund Obere Drau" has resulted in extensive restoration on the River Drau, aimed to improve the ecological integrity of the river ecosystem, to arrest riverbed degradation, and to ensure flood protection. An essential part of the restoration design involved the consideration of self-forming river processes, which led to new demands being imposed on river management. This paper illustrates how model complexity is adapted to the solution and evaluation of different aspects of river restoration problems in a specific case. Point-scale monitoring data were up-scaled to the whole investigation area by means of digital elevation models, and a scaling approach to the choice of model complexity was applied. Simple regime analysis methods and 1-D models are applicable to the evaluation of long-term and reach-scale restoration aims, and to the prediction of kilometre-scale processes (e.g. mean river bed aggradation or degradation, flood protection). 2-D models gave good results for the evaluation of hydraulic changes (e.g. transverse flow velocities, shear stresses, discharges at diffluences) for different morphological units at the local scale (100 m-10 m), and imposed an intermediate demand on calibration data and topographic survey. The study shows that complex 3-D numerical models combined with high resolution digital elevation models are necessary for detailed analysis of processes (1 m-0.01 m), but not for the evaluation of the restoration aims on the River Drau. In conclusion, model choice (complexity) will depend on both lower limits (determined by the complexity of processes to be analysed) and upper limits (field data quality and process understanding for numerical models).

  10. Deriving Flood-Mediated Connectivity between River Channels and Floodplains: Data-Driven Approaches

    Science.gov (United States)

    Zhao, Tongtiegang; Shao, Quanxi; Zhang, Yongyong

    2017-03-01

    The flood-mediated connectivity between river channels and floodplains plays a fundamental role in flood hazard mapping and exerts profound ecological effects. The classic nearest neighbor search (NNS) fails to derive this connectivity because of spatial heterogeneity and continuity. We develop two novel data-driven connectivity-deriving approaches, namely, progressive nearest neighbor search (PNNS) and progressive iterative nearest neighbor search (PiNNS). These approaches are illustrated through a case study in Northern Australia. First, PNNS and PiNNS are employed to identify flood pathways on floodplains through forward tracking. That is, progressive search is performed to associate newly inundated cells in each time step to previously inundated cells. In particular, iterations in PiNNS ensure that the connectivity is continuous - the connection between any two cells along the pathway is built through intermediate inundated cells. Second, inundated floodplain cells are collectively connected to river channel cells through backward tracing. Certain river channel sections are identified to connect to a large number of inundated floodplain cells. That is, the floodwater from these sections causes widespread floodplain inundation. Our proposed approaches take advantage of spatial-temporal data. They can be applied to achieve connectivity from hydro-dynamic and remote sensing data and assist in river basin planning and management.

  11. Significance of large peat blocks for river channel habitat and stream organic budgets

    Directory of Open Access Journals (Sweden)

    S. Crowe

    2007-05-01

    Full Text Available This paper examines the significance of large peat blocks in Trout Beck, an upland gravel-bed river in northern England. An inventory was made of all in-channel peat blocks over a 1.5 km reach of the river in order to characterise the distribution of the blocks, and benthic organic matter and periphyton were sampled from the gravel around an isolated in-channel peat block over a period of four months. Three suspended sediment samplers were installed adjacent to the block to provide estimates of organic drift. At reach scale, peat blocks can be traced to local sources of river bank erosion and show strong downstream fining trends. Analysis of organic matter fluxes indicates that large amounts of peat are eroded from blocks and this substantially increases local organic drift. Microscopic analysis of organic matter particles demonstrates the overwhelming dominance of allochthonous peat in suspension (~ 75 %. Some of this is deposited locally, but in general the amount of organic matter in the drift is substantially greater than that stored in the gravel bed. Therefore, although eroded peat is abundant in the channel system, it is easily transported by the river and thus contributes little to local benthic organic matter storage.

  12. Medium- and short-term channel and island evolution in a disturbed gravel bed river (Brenta River, Italy

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    Johnny Moretto

    2013-03-01

    Full Text Available The timing and extent of the morphological and island changes that have occurred in the last thirty years in a gravel bed river that has been heavily impacted by human activities were analysed by nine sets of aerial photographs, repeated topographical measurements and morphological- vegetation surveys. Dam operations and gravel mining activities have produced modifications in the natural sediment regime that have generated important morphological responses in the channel. Large areas of the formerly active channel were colonised by riparian forest, both as islands and as marginal woodlands. The cessation of gravel extraction in the late 1990s seems to be causing incipient reversion of this pattern, with evidence of vegetation erosion/channel widening. Alteration of sediment regime has played a major role in the medium- and short-term channel evolution. However, only relevant flood events (recurrence interval >10 years appear to determine substantial island erosion and, therefore, the proportion of islands versus channel fluctuates depending on flood history. Smaller scale analysis (sub-reach level was more effective in describing morphological responses and relationships with the sediment dynamics within the 20 km study reach.

  13. Reduced fine sediment flux and channel change in response to the managed diversion of an upland river channel

    Science.gov (United States)

    Perks, Matthew Thomas; Warburton, Jeff

    2016-09-01

    This paper describes the implementation of a novel mitigation approach and subsequent adaptive management, designed to reduce the transfer of fine sediment (post-diversion periods in order to assess the impact of the channel reconfiguration scheme on the fluvial suspended sediment dynamics. Analysis of the river response demonstrates that the fluvial sediment system has become more restrictive with reduced fine sediment transfer. This is characterized by reductions in flow-weighted mean suspended sediment concentrations from 77.93 mg L-1 prior to mitigation, to 74.36 mg L-1 following the diversion. A Mann-Whitney U test found statistically significant differences (p post-monitoring median suspended sediment concentrations (SSCs). Whilst application of one-way analysis of covariance (ANCOVA) on the coefficients of sediment rating curves developed before and after the diversion found statistically significant differences (p model over-predicting sediment concentrations as the channel stabilizes. However, the channel is continuing to adjust to the reconfigured morphology, with evidence of a headward propagating knickpoint which has migrated 120 m at an exponentially decreasing rate over the last 7 years since diversion. The study demonstrates that channel reconfiguration can be effective in mitigating fine sediment flux in headwater streams but the full value of this may take many years to achieve whilst the fluvial system slowly readjusts.

  14. BISTRIȚA RIVER CHANNEL CHANGES IN THE SUBCARPATHIAN SECTOR, IN THE LAST TWO CENTURIES

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    D-.A. CHELARU

    2013-03-01

    Full Text Available Over time, the hydrographic network corresponding to Bistrița basin has undergone numerous changes, mostly human induced, materialized through the hydrotechnical works made in order to create accumulation lakes (especially after 1960, to encrease electricity production, regularization, damming and embankment, land reclamation or achievement of adduction related to public water supply, and also for built-up area or transport routes network expansion. These actions have led to significant changes regarding the hydrographic network morphometry, by reducing the length of the river, degreasing slopes or sinuosity index. The succesion of changes was analyzed by using the following cartographic documents: Austrian maps published by von Otzellowitz (1788-1790, topographic maps (1:50.000 scale published in 1894, military maps (1:20.000 scale edited in 1917-1920, topographic plans (1:5.000 scale, 1975-1976 edition, cadastral plans printed in 1986 (1:10.000 scale and 2005-2006 ortophotomaps at 1:5.000 scale. Overlapping these maps using GIS techniques highlighted the significant reduction of unplaite and sinuosity index. Also, following the deviation of the natural course of Bistrița river through the creation of a 30 kilometers drainage channel were brought important changes to the river channel morphometry, to the position and river confluences angles, and to the whole hydrographic network of the subcarpathian sector of this river.

  15. The Topographic Design of River Channels for Form-Process Linkages

    Science.gov (United States)

    Brown, Rocko A.; Pasternack, Gregory B.; Lin, Tin

    2016-04-01

    Scientists and engineers design river topography for a wide variety of uses, such as experimentation, site remediation, dam mitigation, flood management, and river restoration. A recent advancement has been the notion of topographical design to yield specific fluvial mechanisms in conjunction with natural or environmental flow releases. For example, the flow convergence routing mechanism, whereby shear stress and spatially convergent flow migrate or jump from the topographic high (riffle) to the low point (pool) from low to high discharge, is thought to be a key process able to maintain undular relief in gravel bedded rivers. This paper develops an approach to creating riffle-pool topography with a form-process linkage to the flow convergence routing mechanism using an adjustable, quasi equilibrium synthetic channel model. The link from form to process is made through conceptualizing form-process relationships for riffle-pool couplets into geomorphic covariance structures (GCSs) that are then quantitatively embedded in a synthetic channel model. Herein, GCSs were used to parameterize a geometric model to create five straight, synthetic river channels with varying combinations of bed and width undulations. Shear stress and flow direction predictions from 2D hydrodynamic modeling were used to determine if scenarios recreated aspects of the flow convergence routing mechanism. Results show that the creation of riffle-pool couplets that experience flow convergence in straight channels requires GCSs with covarying bed and width undulations in their topography as supported in the literature. This shows that GCSs are a useful way to translate conceptualizations of form-process linkages into quantitative models of channel form.

  16. Hydroecology of river plankton: the role of variability in channel flow

    Science.gov (United States)

    Reynolds, C. S.

    2000-10-01

    The mechanisms by which entrained planktonic organisms survive in river systems, despite an inexorable, unidirectional downstream transport, are revisited. The importance of channel retentivity to downstream population recruitment is emphasized. The aggregated dead-zone (ADZ) model is shown to be adequate to explain downstream recruitment of a growing population. The ADZ behaviour is more prevalent in sinuous, low-gradient reaches than in other parts of the river. Plankton selection and dynamics relate conspicuously to flow at higher discharges but other environmental features are important at low flows. Discharge variability is pivotal to the opportunities for potamoplankton to thrive.

  17. Channel mapping river miles 29–62 of the Colorado River in Grand Canyon National Park, Arizona, May 2009

    Science.gov (United States)

    Kaplinski, Matt; Hazel, Joseph E.; Grams, Paul E.; Kohl, Keith; Buscombe, Daniel D.; Tusso, Robert B.

    2017-03-23

    Bathymetric, topographic, and grain-size data were collected in May 2009 along a 33-mi reach of the Colorado River in Grand Canyon National Park, Arizona. The study reach is located from river miles 29 to 62 at the confluence of the Colorado and Little Colorado Rivers. Channel bathymetry was mapped using multibeam and singlebeam echosounders, subaerial topography was mapped using ground-based total-stations, and bed-sediment grain-size data were collected using an underwater digital microscope system. These data were combined to produce digital elevation models, spatially variable estimates of digital elevation model uncertainty, georeferenced grain-size data, and bed-sediment distribution maps. This project is a component of a larger effort to monitor the status and trends of sand storage along the Colorado River in Grand Canyon National Park. This report documents the survey methods and post-processing procedures, digital elevation model production and uncertainty assessment, and procedures for bed-sediment classification, and presents the datasets resulting from this study.

  18. Effects of large floods on channel width: recent insights from Italian rivers

    Science.gov (United States)

    Scorpio, Vittoria; Righini, Margherita; Amponsah, William; Crema, Stefano; Ciccarese, Giuseppe; Nardi, Laura; Zoccatelli, Davide; Borga, Marco; Cavalli, Marco; Comiti, Francesco; Corsini, Alessandro; Marchi, Lorenzo; Rinaldi, Massimo; Surian, Nicola

    2017-04-01

    Variations of channel morphology occurring during large flood events (recurrence interval > 50-100 years.) are very often the cause of damages to buildings and infrastructures, as well as of casualties. However, our knowledge of such processes remains poor, as is our capability to predict them. Post-event campaigns documenting channel changes and linking them to hydrological and morphological factors thus bear an enormous value for both the scientific community and river management agencies. We present the results of an analysis on the geomorphic response associated to 4 large floods that occurred between October 2011 and September 2015, affecting several catchments in Northern Italy (Magra-Vara, Trebbia, Nure rivers) and Sardinia (Posada and Mannu di Bitti rivers), characterized by different climatic, lithological and geomorphological settings. The analysis considered more than 400 channel reaches characterized by a drainage area ranging from 39 to 1,100 km2 and featuring a wide range of lateral confinement, mostly within the partly- and unconfined conditions. The approach to flood analysis encompassed: (i) hydrological and hydraulic analysis; (ii) analysis of sediment delivery by landslides to the channel network; (iii) GIS-based and field assessment of morphological channel modifications. For the Nure River flood event (September 2015) a quantitative assessment on average bed level variations was also carried out. Return period for maximum hourly rainfall intensities and peak water discharges exceeded in all basins 100 yr, in some cases even 300 yr. Very high unit peak discharges were estimated, reaching 8.8 m3 s-1km-2 in the Nure River (205 km2) and up to 30 m3 s-1km-2in few Magra River tributaries (5-10 km2). Notable channel widening (post-flood width / pre-flood width > 1.1) occurred in 83% of studied reaches, and it was found more relevant in the channels with narrower initial width, i.e. along the relatively steep tributaries. For these tributaries, the

  19. Changes in floodplain inundation under nonstationary hydrology for an adjustable, alluvial river channel

    Science.gov (United States)

    Call, B. C.; Belmont, P.; Schmidt, J. C.; Wilcock, P. R.

    2017-05-01

    Predicting the frequency and aerial extent of flooding in river valleys is essential for infrastructure design, environmental management, and risk assessment. Conventional flood prediction relies on assumptions of stationary flood distributions and static channel geometries. However, nonstationary flow regimes are increasingly observed and changes in flow and/or sediment supply are known to alter the geometry and flood conveyance of alluvial channels. Systematic changes in flows and/or channel geometry may amplify or attenuate the frequency and/or extent of flood inundation in unexpected ways. We present a stochastic, reduced complexity model to investigate such dynamics. The model routes a series of annual peak discharges through a simplified reach-averaged channel-floodplain cross section. Channel width, depth, and slope are permitted to adjust annually by a user-specified fraction toward equilibrium geometries predicted based on each year's peak discharge and sediment supply. Modeled channel adjustments are compared with empirical observations for two rivers in Minnesota, USA that have experienced multiple large floods over the past 6 years. The model is then run using six hypothetical scenarios simulating nonstationary flow regimes with temporal adjustments in the mean and/or variance of the governing peak-flow distributions. Each scenario is run repeatedly while varying parameters that control the amount of fractional adjustment that channel geometries can make annually. Results indicate that the intra-annual mean horizontal width of floodplain inundation primarily depends on the governing peak-flow distribution's coefficient of variation, but the intra-annual frequency of floodplain inundation (i.e., the fraction of modeled years with inundation) primarily depends on the amount of channel adjustment permitted annually.

  20. The effect of channel shape, bed morphology, and shipwrecks on flow velocities in the Upper St. Clair River

    Science.gov (United States)

    Czuba, Jonathan A.; Oberg, Kevin; Best, Jim; Parsons, Daniel R.

    2009-01-01

    In the Great Lakes of North America, the St. Clair River is the major outlet of Lake Huron and conveys water to Lake St. Clair which then flows to Lake Erie. One major topic of interest is morphological change in the St. Clair River and its impact on water levels in the Upper Great Lakes and connecting channel flows. A combined multibeam echosounder (MBES) bathymetric survey and acoustic Doppler current profiler (ADCP) flow survey of the outlet of Lake Huron and the Upper St. Clair River was conducted July 21 – 25, 2008. This paper presents how channel morphology and shipwrecks affect the flow in the Upper St. Clair River. The river is most constricted at the Blue Water Bridge near Port Huron, Michigan, with water velocities over 2 ms-1 for a flow of 5,200 m3s-1. Downstream of this constriction, the river flows around a bend and expands creating a large recirculation zone along the left bank due to flow separation. This recirculation zone reduces the effective channel width, and thus increases flow velocities to over 2 ms-1 in this region. The surveys reveal several shipwrecks on the bed of the St. Clair River, which possess distinct wakes in their flow velocity downstream of the wrecks. The constriction and expansion of the channel, combined with forcing of the flow by bed topography, initiates channel-scale secondary flow, creating streamwise vortices that maintain coherence downstream over a distance of several channel widths.

  1. Rapid channel incision of the lower Pearl River (China since the 1990s as a consequence of sediment depletion

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    X. X. Lu

    2007-12-01

    Full Text Available This paper reported a dramatic channel incision (>10 m in the deepest cut during the past 10 y or so in the lower Pearl River, the second largest river in terms of water discharge in China. The channel incision had caused changes both in the channel geometry as well as in the river hydraulics. Also, the water exchange between the two major tributaries of the Pearl River, the Xijiang and Beijiang, had been significantly changed due to the channel incision. The rapid channel incision was principally the result of extensive sand mining in the lower Pearl River and the delta region due to the booming economy in the Pearl Delta region. Slight increase of water discharge and significant decrease of sediment load since the early 1990s in both the Xijiang and Beijiang also likely contributed to the observed dramatic river bed downcutting to some extent. This has important implications for river management, as the large Chinese rivers have seen a dramatic depletion of sediment fluxes due to the combined effects of declining rainfall, dam constructions, water diversion, reforestation and afforestation, and sediment mining over the recent decades.

  2. A theoretical analysis of river bars stability under changing channel width

    Science.gov (United States)

    Zen, S.; Zolezzi, G.; Tubino, M.

    2014-04-01

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

  3. Modelling the flooding capacity of a Polish Carpathian river: A comparison of constrained and free channel conditions

    Science.gov (United States)

    Czech, Wiktoria; Radecki-Pawlik, Artur; Wyżga, Bartłomiej; Hajdukiewicz, Hanna

    2016-11-01

    The gravel-bed Biała River, Polish Carpathians, was heavily affected by channelization and channel incision in the twentieth century. Not only were these impacts detrimental to the ecological state of the river, but they also adversely modified the conditions of floodwater retention and flood wave passage. Therefore, a few years ago an erodible corridor was delimited in two sections of the Biała to enable restoration of the river. In these sections, short, channelized reaches located in the vicinity of bridges alternate with longer, unmanaged channel reaches, which either avoided channelization or in which the channel has widened after the channelization scheme ceased to be maintained. Effects of these alternating channel morphologies on the conditions for flood flows were investigated in a study of 10 pairs of neighbouring river cross sections with constrained and freely developed morphology. Discharges of particular recurrence intervals were determined for each cross section using an empirical formula. The morphology of the cross sections together with data about channel slope and roughness of particular parts of the cross sections were used as input data to the hydraulic modelling performed with the one-dimensional steady-flow HEC-RAS software. The results indicated that freely developed cross sections, usually with multithread morphology, are typified by significantly lower water depth but larger width and cross-sectional flow area at particular discharges than single-thread, channelized cross sections. They also exhibit significantly lower average flow velocity, unit stream power, and bed shear stress. The pattern of differences in the hydraulic parameters of flood flows apparent between the two types of river cross sections varies with the discharges of different frequency, and the contrasts in hydraulic parameters between unmanaged and channelized cross sections are most pronounced at low-frequency, high-magnitude floods. However, because of the deep

  4. Historical Channel Adjustment and Estimates of Selected Hydraulic Values in the Lower Sabine River and Lower Brazos River Basins, Texas and Louisiana

    Science.gov (United States)

    Heitmuller, Franklin T.; Greene, Lauren E.

    2009-01-01

    The U.S. Geological Survey, in cooperation with the Texas Water Development Board, evaluated historical channel adjustment and estimated selected hydraulic values at U.S. Geological Survey streamflow-gaging stations in the lower Sabine River Basin in Texas and Louisiana and lower Brazos River Basin in Texas to support geomorphic assessments of the Texas Instream Flow Program. Channel attributes including cross-section geometry, slope, and planform change were evaluated to learn how each river's morphology changed over the years in response to natural and anthropogenic disturbances. Historical and contemporary cross-sectional channel geometries at several gaging stations on each river were compared, planform changes were assessed, and hydraulic values were estimated including mean flow velocity, bed shear stress, Froude numbers, and hydraulic depth. The primary sources of historical channel morphology information were U.S. Geological Survey hard-copy discharge-measurement field notes. Additional analyses were done using computations of selected flow hydraulics, comparisons of historical and contemporary aerial photographs, comparisons of historical and contemporary ground photographs, evaluations of how frequently stage-discharge rating curves were updated, reviews of stage-discharge relations for field measurements, and considerations of bridge and reservoir construction activities. Based on historical cross sections at three gaging stations downstream from Toledo Bend Reservoir, the lower Sabine River is relatively stable, but is subject to substantial temporary scour-and-fill processes during floods. Exceptions to this characterization of relative stability include an episode of channel aggradation at the Sabine River near Bon Wier, Texas, during the 1930s, and about 2 to 3 feet of channel incision at the Sabine River near Burkeville, Texas, since the late 1950s. The Brazos River, at gaging stations downstream from Waco, Texas, has adjusted to a combination of

  5. Urban river restoration: implications on channel sedimentation patterns and associated ecosystem and human health

    Science.gov (United States)

    Gibbs, H.; Gurnell, A.; Heppell, K.; Spencer, K.

    2012-04-01

    Urban river restoration, which alters the physical and hydraulic conditions of rivers, creates rivers favourable to increased sedimentation through greater sediment availability and heterogeneous flow patterns. Sediments, particularly finer-grained, store contaminants including metals which can have detrimental impacts upon aquatic ecosystems and potentially human health. This research therefore looks at the effect of urban river restoration practices upon sedimentation patterns, the associated changes in sediment metal storage and the potential impact upon river function and use in terms of the aquatic ecosystem and human health. Research was undertaken at four sites on urban rivers in London. The spatial extent of different bed sediment types (unvegetated gravel, sand, finer and sediment around in-channel vegetation) in adjacent restored and unrestored stretches was mapped in July 2010. Additionally, sediments were sampled through the year and analysed for a range of metals and sediment characteristics. Two sites (Chinbrook Meadows and Sutcliffe Park) showed a clear difference in bed sediment type channel cover between the restored and unrestored stretches. The majority of the concrete-lined unrestored stretch at Chinbrook Meadows had no sediment deposition, whereas the restored stretch had over half of the channel occupied by finer sediment either on the open channel bed or accumulated around in-channel vegetation. At Sutcliffe Park, the dominant bed sediment type in the restored stretch was finer sediment on the open bed and accumulated around in-channel vegetation, whereas in the unrestored stretch the dominant bed sediment type was gravel. At both sites there were significant differences in metal concentrations and sediment characteristics between bed sediment types. Metal concentrations, organic matter and % <63µm were generally higher in the finer sediment whether on the open bed or around in-channel vegetation. Total loadings of all metals were greater in

  6. Beyond the threshold for motion: river channel geometry and grain size reflect sediment supply

    Science.gov (United States)

    Pfeiffer, A.; Finnegan, N. J.; Willenbring, J. K.

    2016-12-01

    In many gravel-bedded rivers, floods that fill the ch­­annel banks create just enough shear stress to move the median-sized gravel particles on the bed surface (D50). Because this observation is common and is supported by theory, the coincidence of bankfull flow and the incipient motion of D50 has become a­­ commonly employed assumption. However, not all natural gravel channels actually conform to this simple relationship; some channels maintain bankfull stresses far in excess of the critical stress required to initiate sediment transport. We use a database of >300 gravel-bedded rivers and >600 10Be-derived erosion rates from across North America to explore the hypothesis that sediment supply drives the magnitude of bankfull shear stress relative to the critical stress required to mobilize the median bed surface grain size. We find that the ratio of bankfull to critical stress is significantly higher in West Coast river reaches (2.47, n= 84) than in river reaches in the rest of the continent (1.03, n = 245). This pattern parallels trends in erosion rates (and hence sediment supplies). Supporting our hypothesis, we find a significant correlation between upstream erosion rate and local τ*bf/τ*c at sites where this comparison is possible. Our analysis reveals a decrease in bed surface armoring with increasing τ*bf/τ*c, suggesting that channels accommodate changes in sediment supply through adjustments in bed surface grain size, as predicted through numerical modeling. Our findings demonstrate that sediment supply is encoded in the bankfull hydraulic geometry of gravel-bedded channels through its control on bed surface grain size.

  7. Distribution, persistence, and hydrologic characteristics of salmon spawning habitats in clearwater side channels of the Matanuska River, southcentral Alaska

    Science.gov (United States)

    Curran, Janet H.; McTeague, Monica L.; Burril, Sean E.; Zimmerman, Christian E.

    2011-01-01

    Turbid, glacially influenced rivers are often considered to be poor salmon spawning and rearing habitats and, consequently, little is known about salmon habitats that do occur within rivers of this type. To better understand salmon spawning habitats in the Matanuska River of southcentral Alaska, the distribution and characteristics of clearwater side-channel spawning habitats were determined and compared to spawning habitats in tributaries. More than 100 kilometers of clearwater side channels within the braided mainstem of the Matanuska River were mapped for 2006 from aerial images and ground-based surveys. In reaches selected for historical analysis, side channel locations shifted appreciably between 1949 and 2006, but the relative abundance of clearwater side channels was fairly stable during the same period. Geospatial analysis of side channel distribution shows side channels typically positioned along abandoned bars at the braid plain margin rather than on bars between mainstem channels, and shows a strong correlation of channel abundance with braid plain width. Physical and geomorphic characteristics of the channel and chemical character of the water measured at 19 side channel sites, 6 tributary sites, 4 spring sites, and 5 mainstem channel sites showed conditions suitable for salmon spawning in side channels and tributaries, and a correlation of side channel characteristics with the respective tributary or groundwater source water. Autumn-through-spring monitoring of intergravel water temperatures adjacent to salmon redds (nests) in three side channels and two tributaries indicate adequate accumulated thermal units for incubation and emergence of salmon in side channels and relatively low accumulated thermal units in tributaries.

  8. The resilience of river valleys to deformation in experiments: competition between tectonic advection and channel dynamics

    Science.gov (United States)

    Guerit, Laure; Dominguez, Stéphane; Castelltort, Sébastien; Malavielle, Jacques

    2015-04-01

    In oblique collision settings, parallel and perpendicular components of the relative plate motion can be partitioned into different structures of deformation and may be localized close to the plate boundary, or distributed on a wider region. In the Southern Alps of New Zealand, it has been proposed that two-third of the regional convergence was accommodated by the Alpine Fault, while the remaining motion was distributed in a broad area along the Southern Alps orogenic wedge. To better document and understand the regional dynamics of such systems, reliable markers of the horizontal tectonic motion over geological time scales are needed. In numerical models, it has been shown that river networks are able to record a large amount of distributed strain, and that they can thus be used to reconstruct the mode and rate of distribution away from major active structures (Castelltort et al, NGeo, 2012). In order to explore the controls on river resilience to deformation in a less constrained system, we developed an experimental model to investigate river pattern evolution over a doubly-vergent orogenic wedge growing in a context of oblique convergence. We use a rain-fall system to activate erosion, sediment transport and river development on the model surface. The evolution of the wedge is fully recorded through space and time so we are able to follow the drainage geometry deformation. These experiments confirm that rivers record the distribution of motion along the wedge. Image analysis of channel time-space evolution shows how the fault-parallel and fault-perpendicular components of motion decrease toward the fault and impose rotation to the main trunk valleys. However, the capacity of rivers to act as passive markers of deformation competes with the natural lateral channel dynamics and hillslope-channel couplings which both modify the valleys boundaries. In this sense rivers are dynamic markers, which write both a story of passive rotation imposed by the tectonic velocity

  9. Spatial interpolation of river channel topography using the shortest temporal distance

    Science.gov (United States)

    Zhang, Yanjun; Xian, Cuiling; Chen, Huajin; Grieneisen, Michael L.; Liu, Jiaming; Zhang, Minghua

    2016-11-01

    It is difficult to interpolate river channel topography due to complex anisotropy. As the anisotropy is often caused by river flow, especially the hydrodynamic and transport mechanisms, it is reasonable to incorporate flow velocity into topography interpolator for decreasing the effect of anisotropy. In this study, two new distance metrics defined as the time taken by water flow to travel between two locations are developed, and replace the spatial distance metric or Euclidean distance that is currently used to interpolate topography. One is a shortest temporal distance (STD) metric. The temporal distance (TD) of a path between two nodes is calculated by spatial distance divided by the tangent component of flow velocity along the path, and the STD is searched using the Dijkstra algorithm in all possible paths between two nodes. The other is a modified shortest temporal distance (MSTD) metric in which both the tangent and normal components of flow velocity were combined. They are used to construct the methods for the interpolation of river channel topography. The proposed methods are used to generate the topography of Wuhan Section of Changjiang River and compared with Universal Kriging (UK) and Inverse Distance Weighting (IDW). The results clearly showed that the STD and MSTD based on flow velocity were reliable spatial interpolators. The MSTD, followed by the STD, presents improvement in prediction accuracy relative to both UK and IDW.

  10. Particle size distribution of main-channel-bed sediments along the upper Mississippi River, USA

    Science.gov (United States)

    Remo, Jonathan W. F.; Heine, Reuben A.; Ickes, Brian S.

    2016-07-01

    In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter (D50) of fine to coarse sand. The fine tail (≤ D10) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D90) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past ~ 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel.

  11. Particle size distribution of main-channel-bed sediments along the upper Mississippi River, USA

    Science.gov (United States)

    Remo, Jonathan; Heine, Ruben A.; Ickes, Brian

    2016-01-01

    In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter (D50) of fine to coarse sand. The fine tail (≤ D10) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D90) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past ~ 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel.

  12. A Comparative Study on the Adsorption and Desorption of Nitrogen and Phosphorus by Three Matrixes of Eco-River Channel

    OpenAIRE

    Yujia Song; Huiqing Liu

    2013-01-01

    Eco-river channel building is an effective remediation technology for water body. Selecting appropriate matrix material to build eco-river channel can improve its purification capacity on the pollutants. In this paper, we conducted a comparative study on the adsorption capacity of gravel, sand and zeolite on nitrogen and phosphorus and made an initial analysis on its adsorption mechanism. The results show that, Freundlich isotherm equation can better describe the adsorption properties of thos...

  13. Mitigation of hazards from future lahars from Mount Merapi in the Krasak River channel near Yogyakarta, central Java

    Science.gov (United States)

    Ege, John R.; ,

    1983-01-01

    Procedures for reducing hazards from future lahars and debris flows in the Krasak River channel near Yogyakarta, Central Java, Indonesia, include (1) determining the history of the location, size, and effects of previous lahars and debris flows, and (2) decreasing flow velocities. The first may be accomplished by geologic field mapping along with acquiring information by interviewing local residents, and the second by increasing the cross sectional area of the river channel and constructing barriers in the flow path.

  14. Tracing the contribution of debris flow-dominated channels to gravel-bed torrential river channel: implementing pit-tags in the upper Guil River (French Alps)

    Science.gov (United States)

    Arnaud-Fassetta, Gilles; Lissak, Candide; Fort, Monique; Bétard, François; Carlier, Benoit; Cossart, Etienne; Madelin, Malika; Viel, Vincent; Charnay, Bérengère; Bletterie, Xavier

    2014-05-01

    In the upper, wider reaches of Alpine valleys, shaping of active channels is usually subject to rapid change. It mostly depends upon hydro-climatic variability, runoff concentration and sediment supply, and may result in alternating sequences of fluvial and debris-flow pulses, as recorded in alluvial fans and terraces. Our study, carried in the frame of SAMCO (ANR) project, focuses on the upper Guil River Valley (Queyras, Southern French Alps) cut into the slaty shale "schistes lustrés". Steep, lower order drains carry a contrasted solid discharge, including predominantly sandy-loam particles mixed with gravels and boulders (sandstone schists, ophiolites). Abundant sediment supply by frost shattering, snow avalanche and landslides is then reworked during snowmelt or summer storm runoff events, and may result in catastrophic, very destructive floods along the main channel, as shown by historical records. Following the RI-30 year 2000 flood, our investigations included sediment budgets, i.e. balance of erosion and deposition, and the mapping of the source, transport and storage of various sediments (talus, colluvium, torrential fans, terraces). To better assess sediment fluxes and sediment delivery into the main channel network, we implemented tracers (pit-tags) in selected sub-catchments, significantly contributing to the sediment yield of the valley bottoms during the floods and/or avalanches: Maloqueste, Combe Morel, Bouchouse and Peyronnelle catchments. The first three are direct tributaries of the Guil River whereas the Peyronnelle is a left bank tributary of the Peynin River, which joins the Guil River via an alluvial cone with high human and material stakes. The Maloqueste and the Combe Morel are two tributaries facing each other in the Guil valley, representing a double lateral constraint for the road during flood events of the Guil River. After pit-tag initialisation in laboratory, we set them up along the four tributaries: Maloqueste (20 pit-tags), Combe

  15. UAV Measurement of the 2015 Large Flood Impact in Kinugawa River on Riverine Vegetation and Channel Form Changes

    Science.gov (United States)

    Miyamoto, Hitoshi; Inoue, Toshiya; Chigasaki, Yuka

    2016-04-01

    This presentation gives the results of field observation for a flood impact on riverine environment measured by using an unmanned aerial vehicle (UAV). The flood we examined occurred on September 9-10, 2015 in Kinugawa River, Japan, owing to the heavy rainfall that brought tremendous volume of water on the Kanto and Tohoku regions of Japan. In Kinugawa River, the largest record flood occurred in this time, resulting in the levee failure and the corresponding flood disaster in Joso City located in the downstream part of Kinugawa River, as well as the large flood impact on the riverine environment in the Kinugawa channel network. In order to investigate the very initial state of the after-flood-impact throughout the channel network, 13 channel sections with 2 km in longitudinal length were chosen and observed in October 2015. Orthochromatic images of the river channel sections obtained by the UAV measurement with a geographic information system (GIS) were used for analyzing the changes in riverine vegetation distributions and channel form profiles. The results show that there exist three characteristic river segments having different impact-response states in vegetation and channel form changes. The river sections in the most upstream segment indicated severe damage of trees and herbs as well as large movement of gravel bed material, while those in the most downstream segment showed relatively small damage in vegetation distribution and small change in channel forms. Furthermore, relationships between the vegetation damage, channel deformation, channel slopes, and bed shear stresses calculated by a numerical simulation model were discussed in detail along the river network.

  16. The role of riparian vegetation density, channel orientation and water velocity in determining river temperature dynamics

    Science.gov (United States)

    Garner, Grace; Malcolm, Iain A.; Sadler, Jonathan P.; Hannah, David M.

    2017-10-01

    A simulation experiment was used to understand the importance of riparian vegetation density, channel orientation and flow velocity for stream energy budgets and river temperature dynamics. Water temperature and meteorological observations were obtained in addition to hemispherical photographs along a ∼1 km reach of the Girnock Burn, a tributary of the Aberdeenshire Dee, Scotland. Data from nine hemispherical images (representing different uniform canopy density scenarios) were used to parameterise a deterministic net radiation model and simulate radiative fluxes. For each vegetation scenario, the effects of eight channel orientations were investigated by changing the position of north at 45° intervals in each hemispheric image. Simulated radiative fluxes and observed turbulent fluxes drove a high-resolution water temperature model of the reach. Simulations were performed under low and high water velocity scenarios. Both velocity scenarios yielded decreases in mean (≥1.6 °C) and maximum (≥3.0 °C) temperature as canopy density increased. Slow-flowing water resided longer within the reach, which enhanced heat accumulation and dissipation, and drove higher maximum and lower minimum temperatures. Intermediate levels of shade produced highly variable energy flux and water temperature dynamics depending on the channel orientation and thus the time of day when the channel was shaded. We demonstrate that in many reaches relatively sparse but strategically located vegetation could produce substantial reductions in maximum temperature and suggest that these criteria are used to inform future river management.

  17. Documenting Temporal Changes in Channel Geometry of the Buffalo RiverResulting from a Large-Scale Environmental Dredging Project

    Science.gov (United States)

    Singer, J.; Bajo, J. V.; Pfender, K.; Luther, B.

    2016-12-01

    The Buffalo River is classified as a Great Lakes Area of Concern due to loss of habitat, poor water quality, and contaminated bottom sediments. Much attention is being paid to restoring the environmental health of the river with the goal to address the environmental impairments and de-list the river. In support of this effort, an environmental dredging project taking place between 2011 and 2015 removed over 1 million cubic yards of highly contaminated sediment. To support this project, sounding surveys were conducted before, during, and after removal of sediment to determine the amount of sediment to be removed from different 'dredge cells' in the river. These digital data, available upon request from the United States Army Corps of Engineers and the United States Environmental Protection Agency, are being used to generate digital elevation models (DEMs) using ArcGIS 10.3.1. The DEMs are compared to show channel topography and generate cross sectional profiles. Findings show channel deepening of several meters along with channel widening >10m in some dredged portions of the river. Other areas show decrease in depth and suggest local slumping and redeposition of dredged sediment. The sounding data available throughout the stages of the environmental dredging project support an improved understanding of the temporal changes to Buffalo River's channel resulting from the dredging project. The findings also advance our fundamental understanding about the response by rivers to channel modifications.

  18. A Computer Method of Steady Non-Uniform Gradually Varied Flow in Open Channel & in River

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Most of water flow in open channel or in river belongs to steady non-uniform flow. The surface profiles are caused by changes of channel section. It is very important to analyze its computation. According to the regularity of its surface change, the suitable sectional dimensions of open channel or flood control work can be designed. Commonly, computation of non-uniform flow adopts the traditional methods by hand or by graphic method. The speed and precision of computation are restricted. In this paper, a software to calculate water surface profile is introduced. The software is put forward by using C++ .By means of interpolate method and dialogue between user and computer, we can calculate the water surface profile much more quickly and exactly.

  19. Two-dimensional numerical modeling of the longitudinal and lateral channel deformations in alluvial rivers

    Institute of Scientific and Technical Information of China (English)

    XIA Junqiang; WANG Guangqian; WU Baosheng

    2004-01-01

    Two kinds of bank erosion mechanisms were analyzed, including fluvial and non-fluvial controlled mechanisms, and mechanical methods of simulating the erosion processes of cohesive, non-cohesive and composite riverbanks were improved. Then a two-dimensional numerical model of the channel deformation was developed, consisting of a 2D flow and sediment transport submodel and bank-erosion submodels of different soil riverbanks. In the model, a new technique for updating the bank geometry during the bed evolution was presented, which combines closely two kinds of submodels. The proposed model is capable of not only predicting the processes of flood routing and longitudinal channel deformation in natural rivers, but also simulating the processes of lateral channel deformation, especially the processes of lateral erosion and failure of cohesive, non-cohesive and composite riverbanks.

  20. River restoration strategies in channelized, low-gradient landscapes of West Tennessee, USA

    Science.gov (United States)

    Smith, D.P.; Diehl, T.H.; Turrini-Smith, L. A.; Maas-Baldwin, J.; Croyle, Z.

    2009-01-01

    West Tennessee has a complex history of watershed disturbance, including agricultural erosion, channelization, accelerated valley sedimentation, and the removal and reestablishment of beaver. Watershed management has evolved from fl oodplain drainage via pervasive channelization to include local drainage canal maintenance and local river restoration. Many unmaintained canals are undergoing excessive aggradation and complex channel evolution driven by upland erosion and low valley gradient. The locus of aggradation in fully occluded canals (valley plugs) moves up-valley as sediment continues to accumulate in the backwater behind the plug. Valley plugs that cause canal avulsion can lead to redevelopment of meandering channels in less disturbed areas of the fl oodplain, in a process of passive self-restoration. Some valley plugs have brought restored fl oodplain function, reoccupation of extant historic river channels, and formation of a "sediment shadow" that protects downstream reaches from excess sedimentation. Despite the presence of numerous opportunities, there is presently no mechanism for including valley plugs in mitigation projects. In 1997 a survey of 14 reference reach cross sections documented relations between drainage area and bankfull geometry of relatively unmodified streams in West Tennessee. Reassessment of seven of those sites in 2007 showed that one had been dammed by beaver and that two sites could not be analyzed further because of signifi cant vertical or lateral instability. In contrast to other regions of North America, the results suggest that stream channels in this region fl ood more frequently than once each year, and can remain out of banks for several weeks each year. ?? 2009 Geological Society of America.

  1. Geomorphic Classification and Evaluation of Channel Width and Emergent Sandbar Habitat Relations on the Lower Platte River, Nebraska

    Science.gov (United States)

    Elliott, Caroline M.

    2011-01-01

    This report presents a summary of geomorphic characteristics extracted from aerial imagery for three broad segments of the Lower Platte River. This report includes a summary of the longitudinal multivariate classification in Elliott and others (2009) and presents a new analysis of total channel width and habitat variables. Three segments on the lower 102.8 miles of the Lower Platte River are addressed in this report: the Loup River to the Elkhorn River (70 miles long), the Elkhorn River to Salt Creek (6.9 miles long), and Salt Creek to the Missouri River (25.9 miles long). The locations of these segments were determined by the locations of tributaries potentially significant to the hydrology or sediment supply of the Lower Platte River. This report summarizes channel characteristics as mapped from July 2006 aerial imagery including river width, valley width, channel curvature, and in-channel habitat features. In-channel habitat measurements were not made under consistent hydrologic conditions and must be considered general estimates of channel condition in late July 2006. Longitudinal patterns in these features are explored and are summarized in the context of the longitudinal multivariate classification in Elliott and others (2009) for the three Lower Platte River segments. Detailed descriptions of data collection and classification methods are described in Elliott and others (2009). Nesting data for the endangered interior least tern (Sternula antillarum) and threatened piping plover (Charadrius melodus) from 2006 through 2009 are examined within the context of the multivariate classification and Lower Platte River segments. The widest reaches of the Lower Platte River are located in the segment downstream from the Loup River to the Elkhorn River. This segment also has the widest valley and highest degree of braiding of the three segments and many large vegetated islands. The short segment of river between the Elkhorn River and Salt Creek has a fairly low valley

  2. An exploratory historical analysis of biogeomorphological changes in a channelized regulated river

    Science.gov (United States)

    Serlet, Alyssa; Gurnell, Angela; Zolezzi, Guido; Jourdain, Camille; Belleudy, Philippe

    2017-04-01

    Many recent studies have analysed historical information sources to explore the impact of human activities on river morphology and vegetation, but investigations of channelized rivers have been relatively rare. We address this research gap by investigating the historical evolution of morphology and vegetation within a 33 km straightened and embanked reach of the River Isère, a tributary of the Rhône in southeast France. The goal of this study is to establish the trajectory of biogemorphological development of the 33 km reach since the beginning of the 20th century in response to changing human pressures and interventions. Achieving this goal should lead to an improved understanding of how mainly woody vegetation and fluvial processes interact in a heavily human-impacted setting, which in turn should lead to the development of better informed management strategies. The study reach was braided prior to channelisation in 1858, when the river was confined to a single straight channel between embankments. Since the mid 20th century, the river's flow and sediment transport regimes have become increasingly influenced by hydropower development as well as by sediment mining within the studied reach between 1948 and 1973. By extracting information from the historical sources across a range of space and time scales, we identify temporal trajectories of morphological and vegetation development in response to these human interventions. In particular, we identify a progressive development of alternate bars that become vegetated and also enlarge and coalesce through the study period. These processes are evident throughout the study reach but they follow different temporal trajectories within different parts of the reach. We propose tentative links between these biogeomorphic trajectories and human causal factors while at the same time emphasising some limiting aspects of the analysis of such historical data sets.

  3. Differences in ichthyofauna feeding habits among lateral lagoons and the river channel in a large reservoir.

    Science.gov (United States)

    Ferrareze, M; Nogueira, M G; Casatti, L

    2015-05-01

    In this study, we investigated differences in feeding habits of small-sized ichthyofauna among lateral lagoons and the river channel in a large reservoir. The study was performed in four lagoons and in one sampling site of the main channel in Rosana Reservoir, Paranapanema River, Brazil. The samples were taken in September and November of 2004 and in January, March, May, and August of 2005. Fish were sampled with a 7.5 m2 hand net. Five manual throws were made toward aquatic macrophytes stands. The sampling design favored the collection of small-sized fish fauna (juveniles/small-sized species). The stomach contents of 42 species were analyzed. A total of 183 different items were consumed by fish. These items were grouped in 11 food categories, which were used to classify fish into seven trophic guilds. Aquatic insects were consumed by 32 species and were the predominant feeding item. In the river, the most consumed items were aquatic insects, cladocerans, and phytoplankton, whereas in the lagoons aquatic insects, copepods, and cladocerans were the main items. By comparing each trophic guild, the number of insectivores, algivores, and zooplanktivores species was higher in the lagoons than in the river, and the opposite was found only for omnivore fish. Low niche width in all sites indicates high trophic specialization and low niche overlap between pairs of species. Fish assemblage in the lateral lagoons presents feeding habits distinct from those of the river species, indicating that the coexistence and high abundance of small-sized fish in the sampling sites are explained by their high feeding adaptability, which includes a tendency toward dietary specialization, low feeding overlap, and resource partitioning, along with different temporal resource uses.

  4. Differences in ichthyofauna feeding habits among lateral lagoons and the river channel in a large reservoir

    Directory of Open Access Journals (Sweden)

    M. Ferrareze

    Full Text Available In this study, we investigated differences in feeding habits of small-sized ichthyofauna among lateral lagoons and the river channel in a large reservoir. The study was performed in four lagoons and in one sampling site of the main channel in Rosana Reservoir, Paranapanema River, Brazil. The samples were taken in September and November of 2004 and in January, March, May, and August of 2005. Fish were sampled with a 7.5 m2 hand net. Five manual throws were made toward aquatic macrophytes stands. The sampling design favored the collection of small-sized fish fauna (juveniles/small-sized species. The stomach contents of 42 species were analyzed. A total of 183 different items were consumed by fish. These items were grouped in 11 food categories, which were used to classify fish into seven trophic guilds. Aquatic insects were consumed by 32 species and were the predominant feeding item. In the river, the most consumed items were aquatic insects, cladocerans, and phytoplankton, whereas in the lagoons aquatic insects, copepods, and cladocerans were the main items. By comparing each trophic guild, the number of insectivores, algivores, and zooplanktivores species was higher in the lagoons than in the river, and the opposite was found only for omnivore fish. Low niche width in all sites indicates high trophic specialization and low niche overlap between pairs of species. Fish assemblage in the lateral lagoons presents feeding habits distinct from those of the river species, indicating that the coexistence and high abundance of small-sized fish in the sampling sites are explained by their high feeding adaptability, which includes a tendency toward dietary specialization, low feeding overlap, and resource partitioning, along with different temporal resource uses.

  5. Historical and simulated changes in channel characteristics of the Kalamazoo River, Plainwell to Otesgo, Michigan

    Science.gov (United States)

    Rachol, Cynthia M.; Fitzpatrick, Faith A.; Rossi, Tiffiny

    2005-01-01

    In a study to understand the historical effects of the construction and decommissioning of dams on the Kalamazoo River, Plainwell to Otesgo, Michigan, and to simulate channel changes that may result if the dams were removed, early to mid-1800s General Land Office surveys and aerial photographs from 1938, 1981, and 1999 were compared in order to identify historical changes in the river’s planform. This analysis of the 80-mile reach from Morrow Dam to the river mouth at Saugatuck provided insight into how susceptible the river has been to channel migration. The comparison showed that changes in channel width and location were caused mainly by construction of dams and subsequent water-level adjustments in the impounded reaches upstream from the dams. Braiding also occurred downstream from one of the dams. Minor changes in channel form that were not caused by the dams, such as the development and cutoff of meander bends, were observed. A more detailed study in a 5-mile reach passing through the Plainwell and Otsego City Dams included compiling existing valley cross section and longitudinal profile data into a database, assessing bank stability, and using a hydrologic model to simulate the channel as if the dams were removed. Fifty-four valley cross sections compiled from United States Geological Survey and consultant data sets were used as a base for a bank-stability assessment and to design a hypothetical stable channel without the two dams. The channel design involved adjusting the slope, hydraulic geometry, and floodplain width to ensure that water could be transferred through the reach without increasing flooding or erosion problems. The bank-stability assessment focused on conditions that are critical to failure. This was accomplished through the use of a two step process. The first involved evaluating the sediment removed from the bank toe when the stage is high. The second involved calculating the factor of safety for the bank based on the water table being

  6. Quantifying Channel Morphology Changes in Response to the Removal of the Glines Canyon Dam, Elwha River, Washington

    Science.gov (United States)

    Free, B. J.; Ely, L. L.; Hickey, R.; Flake, R.; Baumgartner, S.

    2014-12-01

    The removal of two dams on the Elwha River, Washington, is the largest dam-removal project in history. Our research documents the sediment deposition, erosion, and channel changes between the dams following the initial sediment release from the removal of the upstream Glines Canyon Dam. Within the first year following the dam removal, the pulse of coarse sediment and large woody debris propagated downstream well over 6 km below the dam. The sediment deposition and altered channel hydraulics caused lateral channel migration where anabranching channels merge around new mid-channel bars and at large bends in the river channel. Documenting the river channel response to this exceptional sediment pulse could improve models of the impacts of future dam removals on similar gravel-bed rivers. We quantified the sediment flux and channel changes at four field sites 2-6 km downstream of Glines Canyon Dam. Topographic changes were surveyed with a terrestrial laser scanner (TLS) on an annual basis from August 2012 - August 2014 and the surface sediment distribution was quantified with bimonthly sediment counts. Differencing the annual TLS data yielded an overall increase in sediment throughout the study reach, with a minimum of 20,000 m3 of deposition on bars and banks exposed above the water surface in each 700-m-long TLS survey reach. The surface sediment distribution decreased from ~18 cm to dam removal began to re-emerge due to the remobilizing of sediment through the system.

  7. Sediment Trapping by Emerged Channel Bars in the Lowermost Mississippi River during a Major Flood

    Directory of Open Access Journals (Sweden)

    Bo Wang

    2015-11-01

    Full Text Available The formation of channel bars has been recognized as the most significant sediment response to the highly trained Mississippi River (MR. However, no quantitative study exists on the dynamics of emerged channel bars and associated sediment accumulation in the last 500-kilometer reach of the MR from the Gulf of Mexico outlet, also known as the lowermost Mississippi River. Such knowledge is especially critical for riverine sediment management to impede coastal land loss in the Mississippi River Delta. In this study, we utilized a series of satellite images taken from August 2010 to January 2012 to assess the changes in surface area and volume of three large emerged channel bars in the lowermost MR following an unprecedented spring flood in 2011. River stage data were collected to develop a rating curve of surface areas detected by satellite images with flow conditions for each of the three bars. A uniform geometry associated with the areal change was assumed to estimate the bar volume changes. Our study reveals that the 2011 spring flood increased the surface area of the bars by 3.5% to 11.1%, resulting in a total surface increase of 7.3%, or 424,000 m2. Based on the surface area change, we estimated a total bar volume increase of 4.4%, or 1,219,900 m3. This volume increase would be equivalent to a sediment trapping of approximately 1.0 million metric tons, assuming a sediment bulk density of 1.2 metric tons per cubic meter. This large quantity of sediment is likely an underestimation because of the neglect of subaqueous bar area change and the assumption of a uniform geometry in volume estimation. Nonetheless, the results imply that channel bars in the lowermost MR are capable of capturing a substantial amount of sediment during floods, and that a thorough assessment of their long-term change can provide important insights into sediment trapping in the lowermost MR as well as the feasibility of proposed river sediment diversions.

  8. Medium and short-term channel planform changes on the Rivers Tay and Tummel, Scotland

    Science.gov (United States)

    Winterbottom, Sandra J.

    2000-09-01

    Channel planform change was analysed using a variety of data-sources for the medium-term (>25 years and Tay and Tummel, Scotland. Map data were input into a Geographic Information System (GIS) and used to determine planform characteristics and changes in width, braiding index and sinuosity for the study reach between 1755 and 1976. Aerial photographs were utilised to determine the more recent changes that had taken place between 1971 and 1994. The analysis showed that significant changes had occurred over the medium term with a mean reduction in channel width of 34% for this period. These changes are comparable to those found in studies of similar European rivers for this period. Changes determined for the short-term displayed a continuance of this trend at a comparable rate of change. An analysis of flood frequency and magnitude, precipitation and discharge records for both periods does not show an associated decrease and therefore does not reflect the changes in channel planform. Evidence points towards flood embankment construction in the mid-1800s as the initial cause of channel change for the study reach which was later exacerbated by flow regulation. Incision and the subsequent stabilisation of lateral and mid-channel gravel bars by vegetation succession has resulted in an overall increase in the stability of the study reach which has persisted even where the embankments have fallen into disrepair.

  9. Compliance Monitoring of Underwater Blasting for Rock Removal at Warrior Point, Columbia River Channel Improvement Project, 2009/2010

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Thomas J.; Johnson, Gary E.; Woodley, Christa M.; Skalski, J. R.; Seaburg, Adam

    2011-05-10

    The U.S. Army Corps of Engineers, Portland District (USACE) conducted the 20-year Columbia River Channel Improvement Project (CRCIP) to deepen the navigation channel between Portland, Oregon, and the Pacific Ocean to allow transit of fully loaded Panamax ships (100 ft wide, 600 to 700 ft long, and draft 45 to 50 ft). In the vicinity of Warrior Point, between river miles (RM) 87 and 88 near St. Helens, Oregon, the USACE conducted underwater blasting and dredging to remove 300,000 yd3 of a basalt rock formation to reach a depth of 44 ft in the Columbia River navigation channel. The purpose of this report is to document methods and results of the compliance monitoring study for the blasting project at Warrior Point in the Columbia River.

  10. Evaluation of Lower Umatilla River Channel Modifications Below Three Mile Dam, 1984 Annual Progress Report.

    Energy Technology Data Exchange (ETDEWEB)

    Nigro, Anthony A.; Ward, David L.

    1985-05-01

    This report summarizes results of the first year of a study initiated in September 1984 to evaluate the adequacy of channel modifications made in the lower Umatilla River to improve adult anadromous salmonid passage to Three Mile Dam (RKm 5.6), determine if fish passage or delay problems exist at Three Mile Dam and recommend site specific corrective measures if needed. Movements of steelhead (Salmo gairdneri) were monitored using mark and recapture and radio telemetry techniques. Thirty-four steelhead were marked with T-anchor tags and released in the lower river. Fifteen of those marked were also fitted with radio transmitters. Three radiotagged steelhead migrated through channel modifications to Three Mile Dam. Two of these fish migrated to the dam in less than 26 hours, but held just below the dam for 7 and 10 days before entering the ladders. The third steelhead delayed for 30 days and entered the west ladder within 24 hours of arrival at the dam. Two other radiotagged steelhead moved upstream through some of the channel modifications but did not migrate to the dam. Only one of 19 marked steelhead not fitted with transmitters was recovered at Three Mile Dam. 14 refs., 18 figs., 3 tabs.

  11. Channel and Floodplain Change Analysis over a 100-Year Period: Lower Yuba River, California

    Directory of Open Access Journals (Sweden)

    Rolf Aalto

    2010-07-01

    Full Text Available Hydraulic gold mining in the Sierra Nevada, California (1853–1884 displaced ~1.1 billion m3 of sediment from upland placer gravels that were deposited along piedmont rivers below dams where floods can remobilize them. This study uses topographic and planimetric data from detailed 1906 topographic maps, 1999 photogrammetric data, and pre- and post-flood aerial photographs to document historic sediment erosion and deposition along the lower Yuba River due to individual floods at the reach scale. Differencing of 3 × 3-m topographic data indicates substantial changes in channel morphology and documents 12.6 × 106 m3 of erosion and 5.8 × 106 m3 of deposition in these reaches since 1906. Planimetric and volumetric measurements document spatial and temporal variations of channel enlargement and lateral migration. Over the last century, channels incised up to ~13 m into mining sediments, which dramatically decreased local flood frequencies and increased flood conveyance. These adjustments were punctuated by event-scale geomorphic changes that redistributed sediment and associated contaminants to downstream lowlands.

  12. Quantifying downstream impacts of impoundment on flow regime and channel planform, lower Trinity River, Texas

    Science.gov (United States)

    Wellmeyer, Jessica L.; Slattery, Michael C.; Phillips, Jonathan D.

    2005-07-01

    As human population worldwide has grown, so has interest in harnessing and manipulating the flow of water for the benefit of humans. The Trinity River of eastern Texas is one such watershed greatly impacted by engineering and urbanization. Draining the Dallas-Fort Worth metroplex, just under 30 reservoirs are in operation in the basin, regulating flow while containing public supplies, supporting recreation, and providing flood control. Lake Livingston is the lowest, as well as largest, reservoir in the basin, a mere 95 km above the Trinity's outlet near Galveston Bay. This study seeks to describe and quantify channel activity and flow regime, identifying effects of the 1968 closure of Livingston dam. Using historic daily and peak discharge data from USGS gauging stations, flow duration curves are constructed, identifying pre- and post-dam flow conditions. A digital historic photo archive was also constructed using six sets of aerial photographs spanning from 1938 to 1995, and three measures of channel activity applied using a GIS. Results show no changes in high flow conditions following impoundment, while low flows are elevated. However, the entire post-dam period is characterized by significantly higher rainfall, which may be obscuring the full impact of flow regulation. Channel activity rates do not indicate a more stabilized planform following dam closure; rather they suggest that the Trinity River is adjusting itself to the stress of Livingston dam in a slow, gradual process that may not be apparent in a modern time scale.

  13. Channel dynamics and geomorphic resilience in an ephemeral Mediterranean river affected by gravel mining

    Science.gov (United States)

    Calle, Mikel; Alho, Petteri; Benito, Gerardo

    2017-05-01

    Gravel mining has been a widespread activity in ephemeral rivers worldwide whose long-lasting hydrogeomorphological impacts preclude effective implementation of water and environmental policies. This paper presents a GIS-based method for temporal assessment of morphosedimentary changes in relation to in-channel gravel mining in a typical ephemeral Mediterranean stream, namely the Rambla de la Viuda (eastern Spain). The aims of this work were to identify morphosedimentary changes and responses to human activities and floods, quantify river degradations and analyze factors favoring fluvial recovery for further applications in other rivers. Aerial photographs and LiDAR topography data were studied to analyze geomorphic evolution over the past 70 years along a 7.5-km reach of an ephemeral gravel stream that has been mined intensively since the 1970s. To evaluate changes in the riverbed, we mapped comparable units applying morphological, hydraulic, and stability (based on vegetation density and elevation) criteria to 13 sets of aerial photographs taken from 1946 to 2012. A detailed spatiotemporal analysis of comparable units revealed a 50% reduction in the active section and a 20% increase in stable areas, compared to the conditions observed prior to gravel mining. Instream mining was first observed in 1976 aerial photograph covering already up to 50% of the 1956 riverbed area. River degradation since then was quantified by means of a LiDAR DTM and RTK-GPS measurements, which revealed a 3.5-m incision that had started simultaneously with gravel mining. Climate and land use changes were present but the effects were completely masked by changes produced by instream gravel mining. Therefore, river incision/degradation was triggered by scarcity of sediment and lack of longitudinal sedimentary connection, creating an unbalanced river system that is still adjusting to the present hydrosedimentary conditions.

  14. Channel Change and Bed-Material Transport in the Lower Chetco River, Oregon

    Science.gov (United States)

    Wallick, J. Rose; Anderson, Scott W.; Cannon, Charles; O'Connor, Jim E.

    2010-01-01

    The lower Chetco River is a wandering gravel-bed river flanked by abundant and large gravel bars formed of coarse bed-material sediment. Since the early twentieth century, the large gravel bars have been a source of commercial aggregate for which ongoing permitting and aquatic habitat concerns have motivated this assessment of historical channel change and sediment transport rates. Analysis of historical channel change and bed-material transport rates for the lower 18 kilometers shows that the upper reaches of the study area are primarily transport zones, with bar positions fixed by valley geometry and active bars mainly providing transient storage of bed material. Downstream reaches, especially near the confluence of the North Fork Chetco River, are zones of active sedimentation and channel migration. Multiple analyses, supported by direct measurements of bedload during winter 2008-09, indicate that since 1970 the mean annual flux of bed material into the study reach has been about 40,000-100,000 cubic meters per year. Downstream tributary input of bed-material sediment, probably averaging 5-30 percent of the influx coming into the study reach from upstream, is approximately balanced by bed-material attrition by abrasion. Probably little bed material leaves the lower river under natural conditions, with most net influx historically accumulating in wider and more dynamic reaches, especially near the North Fork Chetco River confluence, 8 kilometers upstream from the Pacific Ocean. The year-to-year flux, however, varies tremendously. Some years may have less than 3,000 cubic meters of bed material entering the study area; by contrast, some high-flow years, such as 1982 and 1997, likely have more than 150,000 cubic meters entering the reach. For comparison, the estimated annual volume of gravel extracted from the lower Chetco River for commercial aggregate during 2000-2008 has ranged from 32,000 to 90,000 cubic meters and averaged about 59,000 cubic meters per year

  15. Investigating the Performance of One- and Two-dimensional Flood Models in a Channelized River Network: A Case Study of the Obion River System

    Science.gov (United States)

    Kalyanapu, A. J.; Dullo, T. T.; Thornton, J. C.; Auld, L. A.

    2015-12-01

    Obion River, is located in the northwestern Tennessee region, and discharges into the Mississippi River. In the past, the river system was largely channelized for agricultural purposes that resulted in increased erosion, loss of wildlife habitat and downstream flood risks. These impacts are now being slowly reversed mainly due to wetland restoration. The river system is characterized by a large network of "loops" around the main channels that hold water either from excess flows or due to flow diversions. Without data on each individual channel, levee, canal, or pond it is not known where the water flows from or to. In some segments along the river, the natural channel has been altered and rerouted by the farmers for their irrigation purposes. Satellite imagery can aid in identifying these features, but its spatial coverage is temporally sparse. All the alterations that have been done to the watershed make it difficult to develop hydraulic models, which could predict flooding and droughts. This is especially true when building one-dimensional (1D) hydraulic models compared to two-dimensional (2D) models, as the former cannot adequately simulate lateral flows in the floodplain and in complex terrains. The objective of this study therefore is to study the performance of 1D and 2D flood models in this complex river system, evaluate the limitations of 1D models and highlight the advantages of 2D models. The study presents the application of HEC-RAS and HEC-2D models developed by the Hydrologic Engineering Center (HEC), a division of the US Army Corps of Engineers. The broader impacts of this study is the development of best practices for developing flood models in channelized river systems and in agricultural watersheds.

  16. Preliminary assessment of channel stability and bed-material transport in the Rogue River basin, southwestern Oregon

    Science.gov (United States)

    Jones, Krista L.; O'Connor, Jim E.; Keith, Mackenzie K.; Mangano, Joseph F.; Wallick, J. Rose

    2012-01-01

    This report summarizes a preliminary assessment of bed-material transport, vertical and lateral channel changes, and existing datasets for the Rogue River basin, which encompasses 13,390 square kilometers (km2) along the southwestern Oregon coast. This study, conducted to inform permitting decisions regarding instream gravel mining, revealed that: * The Rogue River in its lowermost 178.5 kilometers (km) alternates between confined and unconfined segments, and is predominately alluvial along its lowermost 44 km. The study area on the mainstem Rogue River can be divided into five reaches based on topography, hydrology, and tidal influence. The largely confined, active channel flows over bedrock and coarse bed material composed chiefly of boulders and cobbles in the Grants Pass (river kilometers [RKM] 178.5-152.8), Merlin (RKM 152.8-132.7), and Galice Reaches (RKM 132.7-43.9). Within these confined reaches, the channel contains few bars and has stable planforms except for locally wider segments such as the Brushy Chutes area in the Merlin Reach. Conversely, the active channel flows over predominately alluvial material and contains nearly continuous gravel bars in the Lobster Creek Reach (RKM 43.9-6.7). The channel in the Tidal Reach (RKM 6.7-0) is also alluvial, but tidally affected and unconfined until RKM 2. The Lobster Creek and Tidal Reaches contain some of the most extensive bar deposits within the Rogue River study area. * For the 56.6-km-long segment of the Applegate River included in this study, the river was divided into two reaches based on topography. In the Upper Applegate River Reach (RKM 56.6-41.6), the confined, active channel flows over alluvium and bedrock and has few bars. In the Lower Applegate River Reach (RKM 41.6-0), the active channel alternates between confined and unconfined segments, flows predominantly over alluvium, shifts laterally in unconfined sections, and contains more numerous and larger bars. * The 6.5-km segment of the lower

  17. Changes to channel sediments resulting from complex human impacts in a gravel-bed river, Polish Carpathians

    Science.gov (United States)

    Zawiejska, Joanna; Wyżga, Bartłomiej; Hajdukiewicz, Hanna; Radecki-Pawlik, Artur; Mikuś, Paweł

    2016-04-01

    During the second half of the twentieth century, many sections of the Czarny Dunajec River, Polish Carpathians, were considerably modified by channelization as well as gravel-mining and the resultant channel incision (up to 3.5 m). This paper examines changes to the longitudinal pattern of grain size and sorting of bed material in an 18-km-long river reach. Surface bed-material grain size was established on 47 gravel bars and compared with a reference downstream fining trend of bar sediments derived from the sites with average river width and a vertically stable channel. Contrary to expectations, the extraction of cobbles from the channel bed in the upper part of the study reach, conducted in the past decades, has resulted in the marked coarsening of bed material in this river section. The extraction facilitated entrainment of exposed finer grains and has led to rapid bed degradation, whereas the concentration of flood flows in the increasingly deep and narrow channel has increased their competence and enabled a delivery of the coarse particles previously typical of the upstream reach. The middle section of the study reach, channelized to prevent sediment delivery to a downstream reservoir, now transfers the bed material flushed out from the incising upstream section. With considerably increased transport capacity of the river and with sediment delivery from bank erosion eliminated by bank reinforcements, bar sediments in the channelized section are typified by increased size of the finer fraction and better-than-average sorting. In the wide, multi-thread channel in the lower part of the reach, low unit stream power and high channel-form roughness facilitate sediment deposition and are reflected in relatively fine grades of bar gravels. The study showed that selective extraction of larger particles from the channel bed leads to channel incision at and upstream of the mining site. However, unlike bulk gravel mining, selective extraction does not result in sediment

  18. Dynamic channel adjustments in the Jingjiang Reach of the Middle Yangtze River.

    Science.gov (United States)

    Xia, Junqiang; Deng, Shanshan; Lu, Jinyou; Xu, Quanxi; Zong, Quanli; Tan, Guangming

    2016-03-11

    Significant channel adjustments have occurred in the Jingjiang Reach of the Middle Yangtze River, because of the operation of the Three Gorges Project (TGP). The Jingjiang Reach is selected as the study area, covering the Upper Jingjiang Reach (UJR) and Lower Jingjiang Reach (LJR). The reach-scale bankfull channel dimensions in the study reach were calculated annually from 2002 to 2013 by means of a reach-averaged approach and surveyed post-flood profiles at 171 sections. We find from the calculated results that: the reach-scale bankfull widths changed slightly in the UJR and LJR, with the corresponding depths increasing by 1.6 m and 1.0 m; the channel adjustments occurred mainly with respect to bankfull depth because of the construction of large-scale bank revetment works, although there were significant bank erosion processes in local regions without the bank protection engineering. The reach-scale bankfull dimensions in the UJR and LJR generally responded to the previous five-year average fluvial erosion intensity during flood seasons, with higher correlations being obtained for the depth and cross-sectional area. It is concluded that these dynamic adjustments of the channel geometry are a direct result of recent human activities such as the TGP operation.

  19. Dynamic channel adjustments in the Jingjiang Reach of the Middle Yangtze River

    Science.gov (United States)

    Xia, Junqiang; Deng, Shanshan; Lu, Jinyou; Xu, Quanxi; Zong, Quanli; Tan, Guangming

    2016-03-01

    Significant channel adjustments have occurred in the Jingjiang Reach of the Middle Yangtze River, because of the operation of the Three Gorges Project (TGP). The Jingjiang Reach is selected as the study area, covering the Upper Jingjiang Reach (UJR) and Lower Jingjiang Reach (LJR). The reach-scale bankfull channel dimensions in the study reach were calculated annually from 2002 to 2013 by means of a reach-averaged approach and surveyed post-flood profiles at 171 sections. We find from the calculated results that: the reach-scale bankfull widths changed slightly in the UJR and LJR, with the corresponding depths increasing by 1.6 m and 1.0 m the channel adjustments occurred mainly with respect to bankfull depth because of the construction of large-scale bank revetment works, although there were significant bank erosion processes in local regions without the bank protection engineering. The reach-scale bankfull dimensions in the UJR and LJR generally responded to the previous five-year average fluvial erosion intensity during flood seasons, with higher correlations being obtained for the depth and cross-sectional area. It is concluded that these dynamic adjustments of the channel geometry are a direct result of recent human activities such as the TGP operation.

  20. Estimated Entrainment of Dungeness Crab During Dredging For The Columbia River Channel Improvement Project

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, Walter H.; Williams, Greg D.; Skalski, John R.

    2002-12-01

    The studies reported here focus on issues regarding the entrainment of Dungeness crab related to the proposed Columbia River Channel Improvement Project and provided direct measurements of crab entrainment rates at three locations (Desdomona Shoals, Upper Sands, and Miller Sands) from RM4 to RM24 during summer 2002. Entrainment rates for all age classes of crabs ranged from zero at Miller Sands to 0.224 crabs per cy at Desdemona Shoals in June 2002. The overall entrainment rate at Desdomona Shoals in September was 0.120 crabs per cy. A modified Dredge Impact Model (DIM) used the summer 2002 entrainment rates to project crab entrainment and adult equivalent loss and loss to the fishery for the Channel Improvement Project. To improve the projections, entrainment data from Flavel Bar is needed. The literature, analyses of salinity intrusion scenarios, and the summer 2002 site-specific data on entrainment and salinity all indicate that bottom salinity influences crab distribution and entrainment, especially at lower salinities. It is now clear from field measurements of entrainment rates and salinity during a period of low river flow (90-150 Kcfs) and high salinity intrusion that entrainment rates are zero where bottom salinity is less than 16 o/oo most of the time. Further, entrainment rates of 2+ and older crab fall with decreasing salinity in a clear and consistent manner. More elaboration of the crab distribution- salinity model, especially concerning salinity and the movements of 1+ crab, is needed.

  1. Channel-floodplain sediment interactions along large rivers: hydrological connectivity and sediment budgets

    Science.gov (United States)

    Latrubesse, E. M.; Park, E.

    2015-12-01

    Understanding the patterns of sediment delivery processes and their budgets between channel and floodplains of large rivers is important because both hydrogeomorphic and biogeochemical alterations in floodplains take place through these interactions. The Amazon River has continuous exchange of sediment with floodplains, which may exceed over 3500 Mt/yr in both directions. However, characterizing the sediment transport and deposition patterns in floodplains and quantifying their budgets still remains a challenge. In this study, geomorphic units in floodplains are digitized and their hydrological connectivity are assessed by identifying recharge thresholds from the main channel. Historical floodplain recharge records are examined from daily water level data measured at nearby gauge stations by calculating number of days falling in between the connection and disconnection thresholds within a hydrological cycle. Historical recharge patterns of each unit is assessed using Mann-Kendall test. Intensity of hydrological connectivity is further investigated for by building power spectrum of over 15 years water extent time series data through fast Fourier transform, which the power spectral density indicates the intensity of flooding pulses from the main channel. To quantify the sediment budget stored in floodplains, PALSAR DEM acquired during the lowest water level season is used with the MODIS 8-day composite data. First, shoreline grids derived from MODIS-MNDWI is overlaid on PALSAR image to identify the water level at each floodplain lake unit (h). Total imported Sediment Fluxes (TiSF) entering each floodplain lake during a given period will be calculated as sum of (ht1-ht2) x (SSC(x,y)x1000) x 2502, where htn is the water level in floodplain lake at time tn; SSC(x, y) denotes sediment concentration at x, y coordinate; 1000 is a scale factor; and 2502 is the area of MODIS pixel (m2). Successively summing up TiSF derived from each period will retrieve the amount of total

  2. Sediment transport in an active erodible channel bend of Brahmaputra river

    Indian Academy of Sciences (India)

    Tapas Karmaker; Y Ramprasad; Subashisa Dutta

    2010-12-01

    Spatial variation of sediment transport in an alluvial sand-bed river bend needs to be understood with its influencing factors such as bank erosion, secondary current formation, land spur and bed-material characteristics. In this study, detailed hydrographic surveys with Acoustic Doppler Current Profiler (ADCP) were conducted at an active erodible river bend to measure suspended load, velocity, bathymetric profile and characteristics of the bed material. Study indicates the presence of multi-thread flow in the channel bend. Local variation of sediment transport is primarily controlled by active bank erosion, land spur and sand bar formation. Vertical distribution of suspended sediment concentration follows a power function with normalized depth. Average bed-material concentration at the reach level is computed from observed sediment profiles, and is compared against various sediment transport functions. Results show that the sediment transport function suggested by Yang gives better predictions for this reach. Transverse bed slopes at critical survey transects were computed from the bathymetric data and evaluated with analytical approaches. Out of three analytical approaches used, Odgaard’s approach estimates the bed slopes fairly close to the observed one. These two functions are suitable in the Brahmaputra river for further morphological studies.

  3. Channel adjustments in a Mediterranean river over the last 150 years in the context of anthropic and natural controls

    Science.gov (United States)

    Scorpio, Vittoria; Rosskopf, Carmen M.

    2016-12-01

    Evolutionary trajectories and related control factors of the Fortore River (southern Italy) are analyzed over a 150-year period as to assess channel modifications. A multitemporal GIS analysis of topographic maps and aerial photographs together with topographic and geomorphological field surveys were performed. Attention was focused on the impact caused by human disturbance, above all the presence of the Occhito dam at only 40 km upstream of the Fortore mouth (central Adriatic coast). Results show that channel adjustments occurred in three distinct phases and were primarily driven by human disturbance that diversely affected reaches located upstream and downstream of the dam. From the last decades of the nineteenth century to the 1950s (phase 1), channel widening prevailed along upstream reaches whilst narrowing along downstream reaches. Major channel adjustments occurred from the 1950s until the end of the 1990s (phase 2), especially channel narrowing of up to 81% in upstream reaches and 98% in downstream reaches. Narrowing was accompanied by channel-bed lowering of 1 to 5 m and by pattern changes in prevalence from multithread to largely prevailing single-thread channel configurations. In-channel mining, channel works, and hydraulic interventions are considered key driving factors of observed channel adjustments. The closure of the Occhito dam in 1966 had significant and permanent effects on downstream reaches through overall discharge regulation and permanent sediment trapping as also proved by the progressive retreat of the Fortore river mouth area. From 2000 to 2015 (phase 3), a substantial trend inversion was observed with overall channel widening and partial aggradation of upstream reaches and total stabilization of downstream reaches. As highlighted by an integrated multitemporal analysis of recent channel changes and flood events, the latter have played an important role in channel recovery of upstream reaches. Comparison between the Fortore River and

  4. Sediment routing through channel confluences: RFID tracer experiments from a gravel-bed river headwaters

    Science.gov (United States)

    Imhoff, K.; Wilcox, A. C.

    2014-12-01

    Tributary confluences may significantly impact large-scale patterns of sediment transport because of their role in connecting individual streams in a network. These unique locations feature complex flow structures and geomorphic features, and may represent ecological hotspots. Sediment transport across confluences is poorly understood, however. We present research on coarse sediment transport and dispersion through confluences using sediment tracers in the East Fork Bitterroot River, Montana, USA. We tagged a range of gravel (>40 mm) and cobble particles with Radio Frequency Identification (RFID) tags and painted smaller (10-40 mm) gravels, and then we traced them through confluences in a montane river's headwaters. We measured the effects of confluences on dispersion, path length, and depositional location and compare properties of sediment routing with a non-confluence control reach. We also measured topographic change through repeat bed surveys and combined topography, hydraulics, and tracer measurements to calculate basal shear and critical Shields stresses for different grain sizes. Field observations suggest that tagged particles in confluences routed along flanks of scour holes in confluences, with sediment depositing further downstream along bank-lateral bars than within the channel thalweg. Travel distances of RFID-tagged particles ranged up to 35 meters from original seeding points, with initial recovery rates of RFID-tagged tracers ranging between 84-89%. In both confluence and control reaches only partial mobility was observed within the entire tracer population, suggesting a hiding effect imposed by the roughness of the bed. Particles seeded in the channel thalweg experienced further travel distances than those seeded towards the banks and on bars. Differences in dispersion between confluence and control reaches are implied by field observation. This study quantified patterns of sediment routing within confluences and provided insight to the importance

  5. Channel response to extreme floods: Insights on controlling factors from six mountain rivers in northern Apennines, Italy

    Science.gov (United States)

    Surian, Nicola; Righini, Margherita; Lucía, Ana; Nardi, Laura; Amponsah, William; Benvenuti, Marco; Borga, Marco; Cavalli, Marco; Comiti, Francesco; Marchi, Lorenzo; Rinaldi, Massimo; Viero, Alessia

    2016-11-01

    This work addresses the geomorphic response of mountain rivers to extreme floods, exploring the relationships between morphological changes and controlling factors. The research was conducted on six tributaries of the Magra River (northern Apennines, Italy) whose catchments were affected by an extreme flood (estimated recurrence interval > 100 years in most of the basins) on 25 October 2011. An integrated approach was deployed to study this flood, including (i) analysis of channel width changes by comparing aerial photographs taken before and after the flood, (ii) estimate of peak discharges in ungauged streams, (iii) detailed mapping of landslides and analysis of their connectivity with the channel network. Channel widening occurred in 35 reaches out of 39. In reaches with channel slope hydraulic variables alone are not sufficient to satisfactorily explain the channel response to extreme floods, and inclusion of other factors such as lateral confinement is needed to increase explanatory capability of regression models. Concerning hydraulic variables, this study showed that the degree of channel widening is more strongly related to unit stream power calculated based on pre-flood channel width than to cross-sectional stream power and to unit stream power calculated with post-flood channel width. This could suggest that most width changes occurred after the flood peak. Finally, in terms of hazard, it is crucial to document the type and magnitude of channel changes, to identify controlling factors, and most importantly, to develop tools enabling us to predict where major geomorphic changes occur during an extreme flood.

  6. A tale of two rivers: channel adjustments to restorative floods in the Green River in Dinosaur N.M. as compared to those in the Colorado River in Grand Canyon N.P.

    Science.gov (United States)

    Alexander, J. S.; Schmidt, J. C.

    2007-12-01

    Sediment mass balance is a critical system attribute in assessing the potential for restoration of dam-impacted rivers. We compared channel response to large floods on the Green River in Lodore Canyon to similar changes measured along the Colorado River in part of Grand Canyon National Park, a reach with similar geomorphic organization, regulatory constraints, and habitat management goals. The post-dam sediment mass balance of the Green River is indeterminate or in surplus, but the mass balance of the Colorado River is in deficit. Analysis of repeat measurements at 36 cross sections along a 20 km reach of Lodore Canyon show that the sand storage condition in 2006 was no different than the condition observed in 1994, despite an increased frequency of high magnitude floods. Four high magnitude floods occurred in 1997, 1999, 2005, and 2006, but only one, the 1999 flow, triggered channel adjustments to the bed and banks that were significantly different than those of the post- dam 2-year return flood. This condition of relative equilibrium contrasts the sand storage condition of the Colorado River in Grand Canyon, where sand bar area and volume have declined despite specific dam releases intended to rebuild sand bars. The contrasting patterns of channel adjustment in these rivers indicate that the opportunities and cost of restoration are likely to differ in relation to the sediment supply available for channel restoration.

  7. Spatial and temporal variations of the Longxi river channel in Sichuan province after the 2008 Wenchuan earthquake, China

    Science.gov (United States)

    Guo, B.; Xie, T.; Liu, G.

    2015-12-01

    Biyun Guo1,21College of Marine Science and Technology, Zhejiang Ocean University, Zhoushan 316004,China; 2State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China Abstract: The great Wenchuan earthquake(Ms=8.0) occurred on May 12, 2008 in the southwestern China which triggerednumerous landslides and collapses that providedflows of an abundant unconsolidated material of debris. Landslides and debris flows were very active and caused river channel change over the affected mountain area. River channel changes due to the earthquake.Many potentially dangerous debris filledgullies have yet to be identified. In this paper,we present a study in the Longxi river watershed of the upper Min River located in Dujiangyan, discussingthe unconsolidated deposits and debris flows and their relationship with the riverbed changes. The secondary geological disasters triggered by this earthquake is delineated across the Longxi Rvier basin. Based on remote sensing and image interpretation of two QuickBird panchromatic images and comparison between two DEM data of different time periods, wevalidatedthe data with field survey by a differential GPS and laser rangefinder. Several variables were systematically measured (width, slope, bed level change, sediment size) along an18.22 km stretch of the river for specific sites. We have found from the study that: (1) the significant feature of geological disaster was near the Longxi river, where it had the mostintensity; (2) the longitudinal profile of channel bed was changed; (3) channel changes were associated with the land use and cover change, especially with the forest degradation and reforest, and post-quake reconstruction;(4)the landslide and debris flows caused the morphology changes in the Longxi River watershed, leading to sharp changes of the riverbed profiles and the slope in the upper and lower reaches. Keywords: Earthquake ;landslides; debris flows; channel change; riverbed evolution

  8. Seismic facies of incised-channel fill deposits of paleo-Seomjin River in the South Sea, Korea

    Science.gov (United States)

    Bae, Sung Ho; Kong, Gee Soo; Choul Kim, Dae; Lee, Gwang Soo; Yoo, Dong Geun

    2016-04-01

    High-resolution (Chirp and Sparker system) seismic profiles and piston core samples were analyzed to investigate the depositional environment of paleo-channel in the continental shelf of South Sea. Approximately 1,940 line-km data of chirp and sparker profiles was acquired. Along with seismic profiles, 20 piston core and 10 box core samples collected in 2015. The paleo-channel of Seomjin River is distributed in the continental shelf, with approximately 109 km long, 800-5,000 m wide, and more than 890 km2. The paleo-channel of meandering and straight type is dominant in the inner shelf while changed to braided type in the outer shelf. The paleo-channels in sparker seismic data formed presumably as fluvial systems when the shelf was exposed during the Last Glacial Maximum (LGM). The seismic facies of incision fill divided into five types basis of an erosional surface and internal seismic reflectors: (1) transparent to semi-transparent incised channel fill, (2) parallel to sub-parallel incised channel fill, (3) complex incised channel fill, (4) divergent incised channel fill, and (5) chaotic incised channel fill. The chaotic incised channel fill deposits are consists of gravel with shell fragments in the outer shelf and indicate the LGM to early transgressive (fluvial lag deposits). The complex incised channel fill deposits are dominated by sand and gravel with shell fragments in the mid to outer shelf. The cores which were obtained above the transparent to semi-transparent and parallel to sub-parallel incised channel fill deposits are dominated by mud. These types are dominant in the upstream (inner shelf). The acoustically transparent zones of this type with low-energy, passively infilling depositional environment, suggest the presence of basin muddy deposits. These muddy sediments were likely deposited during a more advanced stage of the Holocene transgression. Thus, the paleo-channel of Seomjin River is strongly controlled by sea-level change and sediment

  9. Latest Holocene evolution and human disturbance of a channel segment in the Hudson River Estuary

    Science.gov (United States)

    Klingbeil, A.D.; Sommerfield, C.K.

    2005-01-01

    The latest Holocene sedimentary record of a cohesive channel and subtidal shoal in the lower Hudson River Estuary was examined to elucidate natural (sea-level rise, sediment transport) and anthropogenic (bulkheading, dredging) influences on the recent morphodynamic evolution of the system. To characterize the seafloor and shallow subbottom, ??? 100 km of high-resolution seismic reflection profiles (chirp) were collected within a 20-km reach of the estuary and correlated with sediment lithologies provided by eight vibracores recovered along seismic lines. Sediment geochronology with 137Cs and 14C was used to estimate intermediate and long-term sedimentation rates, respectively, and historical bathymetric data were analyzed to identify regional patterns of accretion and erosion, and to quantify changes in channel geometry and sediment volume. The shoal lithosome originated around 4 ka presumably with decelerating eustatic sea level rise during the latest Holocene. Long-term sedimentation rates on the shoal (2.3-2.6 mm/yr) are higher than in the channel (2 mm/yr) owing to hydrodynamic conditions that preferentially sequester suspended sediment on the western side of the estuary. As a result, the shoal accretes oblique to the principal axis of tidal transport, and more rapidly than the channel to produce an asymmetric cross-section. Shoal deposits consist of tidally bedded muds and are stratified by minor erosion surfaces that seismic profiles reveal to extend for 10s of meters to kilometers. The frequency and continuity of these surfaces suggest that the surficial shoal is catastrophically stripped on decadal-centennial time scales by elevated tidal flows; tidal erosion maintains the shoal at a uniform depth below sea level and prevents it from transitioning to an intertidal environment. Consequently, the long-term sedimentation rate approximates the rate of sea-level rise in the lower estuary (1-3 mm/yr). After the mid 1800s, the natural geometry of the lower Hudson

  10. Designing long-term fish community assessments in connecting channels: Lessons from the Saint Marys River

    Science.gov (United States)

    Schaeffer, Jeff; Rogers, Mark W.; Fielder, David G.; Godby, Neal; Bowen, Anjanette K.; O'Connor, Lisa; Parrish, Josh; Greenwood, Susan; Chong, Stephen; Wright, Greg

    2014-01-01

    Long-term surveys are useful in understanding trends in connecting channel fish communities; a gill net assessment in the Saint Marys River performed periodically since 1975 is the most comprehensive connecting channels sampling program within the Laurentian Great Lakes. We assessed efficiency of that survey, with intent to inform development of assessments at other connecting channels. We evaluated trends in community composition, effort versus estimates of species richness, ability to detect abundance changes for four species, and effects of subsampling yellow perch catches on size and age-structure metrics. Efficiency analysis revealed low power to detect changes in species abundance, whereas reduced effort could be considered to index species richness. Subsampling simulations indicated that subsampling would have allowed reliable estimates of yellow perch (Perca flavescens) population structure, while greatly reducing the number of fish that were assigned ages. Analyses of statistical power and efficiency of current sampling protocols are useful for managers collecting and using these types of data as well as for the development of new monitoring programs. Our approach provides insight into whether survey goals and objectives were being attained and can help evaluate ability of surveys to answer novel questions that arise as management strategies are refined.

  11. Use of glacier river-fed estuary channels by juvenile coho salmon: transitional or rearing habitats?

    Science.gov (United States)

    Hoem Neher, Tammy D.; Rosenberger, Amanda E.; Zimmerman, Christian E.; Walker, Coowe M.; Baird, Steven J.

    2014-01-01

    Estuaries are among the most productive ecosystems in the world and provide important rearing environments for a variety of fish species. Though generally considered important transitional habitats for smolting salmon, little is known about the role that estuaries serve for rearing and the environmental conditions important for salmon. We illustrate how juvenile coho salmonOncorhynchus kisutch use a glacial river-fed estuary based on examination of spatial and seasonal variability in patterns of abundance, fish size, age structure, condition, and local habitat use. Fish abundance was greater in deeper channels with cooler and less variable temperatures, and these habitats were consistently occupied throughout the season. Variability in channel depth and water temperature was negatively associated with fish abundance. Fish size was negatively related to site distance from the upper extent of the tidal influence, while fish condition did not relate to channel location within the estuary ecotone. Our work demonstrates the potential this glacially-fed estuary serves as both transitional and rearing habitat for juvenile coho salmon during smolt emigration to the ocean, and patterns of fish distribution within the estuary correspond to environmental conditions.

  12. Effects of streamflows on stream-channel morphology in the eastern Niobrara National Scenic River, Nebraska, 1988–2010

    Science.gov (United States)

    Schaepe, Nathaniel J.; Alexander, Jason S.; Folz-Donahue, Kiernan

    2016-03-09

    The Niobrara River is an important and valuable economic and ecological resource in northern Nebraska that supports ecotourism, recreational boating, wildlife, fisheries, agriculture, and hydroelectric power. Because of its uniquely rich resources, a 122-kilometer reach of the Niobrara River was designated as a National Scenic River in 1991, which has been jointly managed by the U.S. Fish and Wildlife Service and National Park Service. To assess how the remarkable qualities of the National Scenic River may change if consumptive uses of water are increased above current levels, the U.S. Geological Survey, in cooperation with the National Park Service, initiated an investigation of how stream-channel morphology might be affected by potential decreases in summer streamflows. The study included a 65-kilometer segment in the wide, braided eastern stretch of the Niobrara National Scenic River that provides important nesting habitat for migratory bird species of concern to the Nation.

  13. CHNHYD: a channel hydrodynamic model for simulating flows and water surface elevations in a stream/river network

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.

    1982-01-01

    A description is given of the development of a channel hydrodynamic model for simulating the behavior of flows and water surface elevations in a river network that may consist of any number of joined and branched rivers/streams, including both tidal and nontidal rivers. The model employs a numerical method, an integrated compartment method (ICM). The basic procedures of the ICM are first to discretize the river/stream system into compartments of various sizes, then to apply three integral theorems of vectors to transform the n-dimensional volume integral into an (n - 1)-dimensional surface integral, and finally to close the system by using simple interpolation to relate the interfacial values in terms of the compartment values. Thus, the method greatly facilitates the setup of algebraic equations for the discrete field approximating the corresponding continuous field. Most of the possible boundary conditions that may be anticipated in real-world problems are considered. These include junctions, prescribed flow, prescribed water surface elevation (or cross-sectional area), and rating curve boundaries. The use of ICM makes the implementation of these four types of boundary conditions relatively easy. The model is applied to two case studies: first to a single river and then to a network of five river channels in a watershed. Results indicate that the model can definitely simulate the behavior of the hydrodynamic variables that are required to compute chemical transport in a river/stream network.

  14. Persistent disturbance by commercial navigation afters the relative abundance of channel-dwelling fishes in a large river

    Science.gov (United States)

    Gutreuter, S.; Vallazza, J.M.; Knights, B.C.

    2006-01-01

    We provide the first evidence for chronic effects of disturbance by commercial vessels on the spatial distribution and abundance of fishes in the channels of a large river. Most of the world's large rivers are intensively managed to satisfy increasing demands for commercial shipping, but little research has been conducted to identify and alleviate any adverse consequences of commercial navigation. We used a combination of a gradient sampling design incorporating quasicontrol areas with Akaike's information criterion (AIC)-weighted model averaging to estimate effects of disturbances by commercial vessels on fishes in the upper Mississippi River. Species density, which mainly measured species evenness, decreased with increasing disturbance frequency. The most abundant species - gizzard shad (Dorosoma cepedianum) and freshwater drum (Aplodinotus grunniens) - and the less abundant shovelnose sturgeon (Scaphirhynchus platorhynchus) and flathead catfish (Pylodictis olivaris) were seemingly unaffected by traffic disturbance. In contrast, the relative abundance of the toothed herrings (Hiodon spp.), redhorses (Moxostoma spp.), buffaloes (Ictiobus spp.), channel catfish (Ictalurus punctatus), sauger (Sander canadensis), and white bass (Morone chrysops) decreased with increasing traffic in the navigation channel. We hypothesized that the combination of alteration of hydraulic features within navigation channels and rehabilitation of secondary channels might benefit channel-dependent species. ?? 2006 NRC.

  15. Coupling effect analysis between landslides, river channel changes and sediment budgets - extreme climate events in Laishe River, southern Taiwan

    Science.gov (United States)

    Chang, Kuo-Jen; Huang, Mei-Jen; Tseng, Chih-Ming

    2016-04-01

    amount of migration along Laishe River by analyzing the 3D DEM before and after the typhoon Morakot. The DEMs are built by using the aerial images taken by digital mapping camera (DMC) and by airborne digital scanner 40 (ADS40) before and after typhoon event. Recently, this research integrates Unmanned Aerial Vehicle (UAV) and oblique photogrammetric technologies for image acquisition by 5-10cm GSD photos. This approach permits to construct true 3D model so as to decipher ground information more realistically. 10-20cm DSM and DEM, and field GPS, were compiled together to decipher the morphologic changes. All the information, especially by means of true 3D model, the datasets provides detail ground information that may use to evaluate the landslide triggering mechanism and river channel evolution. The goals of this study is to integrates the UAS system and to decipher the sliding process and morphologic changes of large landslide areas, sediment transport and budgets, and to investigate the phenomenon of river migration. The results of this study provides not only geomatics and GIS dataset of the hazards, but also for essential geomorphologic information for other study, and for hazard mitigation and planning, as well.

  16. Characterization of sands and mineral clays in channel and floodplain deposits of Portuguesa river, Venezuela

    Directory of Open Access Journals (Sweden)

    Orlando José González Clemente

    2013-11-01

    Full Text Available In the main channel and floodplain of Portuguesa River were studied the mineralogical characteristics of sand and clay minerals respectively. The methodology consisted of X-ray diffraction (XRD analysis, for both mineral fractions. The results indicated the presence of mainly of quartz sands with minor amounts of chlorite, muscovite, calcite and feldspar which are considered quartz sand mature. Its origin is related to the source area and rework of soils and sediments of the floodplain. The clay fraction is characterized by the presence of 13 mineral crystalline phases consisting mainly of quartz, muscovite and chlorite, and clay minerals such as kaolinite, vermiculite, montmorillonite and nontronita. Its detrital origin may be due to mineral neoformation and inheritance. Therefore both mineral fractions consist mainly of quartz and kaolinite, which are essential components of the source area as well as the Quaternary alluvial deposits and the soils that make up the region.

  17. Electromagnetic Resistivity Profiling For Locating Buried River Channels: A Case Study In Haiti

    Science.gov (United States)

    Radstake, Frank

    1992-01-01

    The Service National des Ressources en Eau (SNRE) of the Ministry of Agriculture of Haiti, in cooperation with the UNDTCD, carried out a geophysical investigation in the Northern Plain of Haiti. It included a reinterpretation of the available resistivity soundings and the realization of eight additional soundings and 11 electromagnetic profiles. The mathematical interpretation of the soundings permitted the determination of the true resistivity of different lithologies present in the area and the mapping of the thickness of the alluvial aquifer. The results of the five electromagnetic resistivity profiles in the Trou du Nord area are presented, with a total lenght of 17.4 km. They show distinctive resistivity anomalies, which are assumed to represent buried river channels filled with coarse sands and gravels. One of the anomaly zones was explored in more detail and shows clearly lateral resistivity differences at greater depths. The data interpretations have been checked through response calculations of geoelectrical layer models.

  18. Longitudinal dispersion in natural channels: 3. An aggregated dead zone model applied to the River Severn, U.K.

    Science.gov (United States)

    Davis, P. M.; Atkinson, T. C.

    An Aggregated Dead Zone (ADZ) model is presented for longitudinal dispersion of tracer in river channels, in which the channel cross-section is divided into two parallel regions: the bulk flow and dead zone storage. Tracer particles in the bulk flow are assumed to obey plug-flow advection at the discharge velocity U without any mixing effects. The dispersive properties of the model are completely embodied in the residence time for tracer storage in the dead zone. The model provides an excellent description and prediction of empirical concentration-time distributions, for times t ADZ model is a potentially useful tool for practical prediction of dispersion in natural channels.

  19. Principles for River Channel Realignment%黄河河道整治原则

    Institute of Scientific and Technical Information of China (English)

    胡一三

    2001-01-01

    The principles should be obeyed in the Yellow River Channel Realignment are as follows: overall planning, unified river realignment; taking flood prevention as the key, overall consideration; comprehensive harness of both channel and beach; determination of flow path through analysis of law; realignment of normal condition based on consideration of flood and low water; decision of plan according to practice; protection of bend site by use of dam, and diversion of flow relying on the bend; adroitly guide action according to circumstances, and consider projects in dry season first; actively distribute constructions and energetically improve; clarify major and minor, and take urgent issue at first; suit measures to local conditions, use materials from nearby; carry forward good traditions, make development and bring forth new ideas.%黄河河道整治应遵循的原则为:全面规划、团结治河;防洪为主、统筹兼顾;河槽滩地、综合治理;分析规律、确定流路;中水整治、考虑洪枯;依照实践、确定方案;以坝护弯、以弯导溜; 因势利导、优先旱工;主动布点、积极完善;分清主次、先急后缓;因地制宜、就地取材;继承传统、开拓创新。

  20. River Channel Change Simulation of Khoshke Rud Farsan River and Bank Erosion Process Using a Numerical Depth Averaged Model, CCHE2D

    Directory of Open Access Journals (Sweden)

    Mohammad Fathi

    2012-01-01

    Full Text Available Bank erosion in populated areas could cause fatalities and property damage if banks collapse abruptly, compromising the integrity of residential buildings and civil facilities. Bank erosion study is in general a very complex problem because of it involves multi-processes such as bank surface erosion, bank toe erosion and bank material mechanic failure, etc. Each of these processes is related to several parameters: sediment size distribution, bank material cohesion, slope, homogeneity, consolidation, soil moisture and ground water level, as well as bank height. The bank erosion rate is also related to the strength of the flow in the river indicated by the flow shear stress, water depth, and channel curvature, etc. In this study, the numerical model CCHE2D has been applied to study real-world bank erosion cases in a mountain river, Khoske Rud Farsan River, Iran, which is a braided river with high sediment loads and channel mobility; the bank erosion of this river is dominated by floods during rainy seasons.

  1. A Hot Knife Through Ice-Cream: Earthflow Response to Channel Incision (Or Channel Response to Earthflows?), Eel River Canyon, California

    Science.gov (United States)

    Mackey, B. H.; Roering, J. J.; McKean, J. A.

    2007-12-01

    Abundant glacier-like earthflow features are recognized as a primary erosional process in the highly erodable Franciscan Melange of the Eel River Basin, CA. Despite their prominence in this "melting ice-cream" topography, many questions regarding their effects on the long term sediment flux from this rapidly eroding basin remain unresolved. For example, does an earthflow's basal shear zone propagate vertically downwards with vertical river incision? What controls the upslope and lateral extent of individual earthflows? How does the erosive power of a river influence the rate of earthflow movement, or conversely do earthflow toe deposits regulate the rate of river incision? Here we present preliminary findings derived from study of 200km2 of lidar data (1m resolution) covering hillslopes adjacent to 30km of the Eel River. Lidar allows detailed analysis of the interaction between earthflows and the drainage network, and we document how inferred changes in local base level are propagated throughout adjacent hillslopes via earthflow movement. The most active earthflows (determined by field surveying and analysis of aerial photos rectified using lidar- generated digital topography) coincide with locally steep sections of channel, while downstream of the most active flows we frequently observe less-active or dormant earthflows. This observation supports the idea that the locations of the most active earthflows coincide with headward propagating knickpoints in the channel. The rate of earthflow movement appears to slow when an earthflow exhausts the upslope area of easily mobilized sediment. Earthflow toes can protrude directly into the channel, causing the channel to narrow and steepen, and even undercut the opposite bank. Large resistant boulders (>2m diameter) transported by the earthflow accumulate in the streambed and appear to both act as a check on further channel incision and earthflow movement. In contrast, areas adjacent to active earthflows exhibit smooth

  2. Habitat used by juvenile lake sturgeon (Acipenser fulvescens) in the North Channel of the St. Clair River (Michigan, USA)

    Science.gov (United States)

    Boase, James C.; Manny, Bruce A.; Donald, Katherine A.L.; Kennedy, Gregory W.; Diana, James S.; Thomas, Michael V.; Chiotti, Justin A.

    2014-01-01

    Lake sturgeon (Acipenser fulvescens) occupy the St. Clair River, part of a channel connecting lakes Huron and Erie in the Laurentian Great Lakes. In the North Channel of the St. Clair River, juvenile lake sturgeon (3–7 years old and 582–793 mm in length) were studied to determine movement patterns and habitat usage. Fourteen juveniles were implanted with ultrasonic transmitters and tracked June–August of 2004, 2005 and 2006. Telemetry data, Geographic Information System software, side-scan sonar, video images of the river bottom, scuba diving, and benthic substrate samples were used to determine the extent and composition of habitats they occupied. Juvenile lake sturgeon habitat selection was strongly related to water depth. No fish were found in 700 mm in length selected sand and gravel areas mixed with zebra mussels and areas dominated by zebra mussels, while fish < 700 mm used these habitat types in proportion to their availability.

  3. Do Titan's river channels carve into ice bedrock or loose regolith?

    Science.gov (United States)

    Collins, G. C.; Sklar, L. S.; Litwin, K. L.; Polito, P. J.

    2012-04-01

    transportable blocks, and/or that most of the channels are transport-limited and are primarily acting to redistribute an existing loose regolith layer across Titan’s surface. References: Collins, G. C., Relative rates of fluvial bedrock incision on Titan and Earth, Geophys. Res. Lett. 32, L22202, doi:10.1029/2005GL024551, 2005. Keller, H. U., B. Grieger, M. Küppers, S. E. Schröder, Y. V. Skorov, and M. G. Tomasko, The properties of Titan’s surface at the Huygens landing site from DISR observations, Planet. Space Sci. 56, 728-752, 2008. Perron, J. T., M. P. Lamb, C. D. Koven, I. Y. Fung, E. Yager, and M. Ádámkovics, Valley formation and methane precipitation rates on Titan, J. Geophys. Res. 111, E11001, 2006. Sklar, L. S., and W. E. Dietrich, A mechanistic model for river incision into bedrock by saltating bed load, Water Resour. Res. 40, W06301, 2004.

  4. Effect of suspended sediment grain size on channel sedimentation in the lower Yellow River and some implications

    Institute of Scientific and Technical Information of China (English)

    XU JiongXin; HU ChunHong; CHEN JianGuo

    2009-01-01

    Based on the data of suspended sediment transport and channel sedimentation in various grain size fractions in the period of 1962-1985,the relationship between channel sedimentation in the lower Yellow River and sediment input has been plotted with respect to each grain size fraction.Several fill-scour thresholds in sediment input have been identified from these graphs.It was found that the fill-scour threshold in sediment input decreases with the increase in fraction grain size.The correlation coefficient between channel sedimentation and sediment input becomes larger with the increasing fraction grain size,indicating that channel sedimentation depends more on coarser grain size fractions than on smaller ones.The fraction channel sedimentation induced by unit change of fraction sediment input increases with grain size.Of the input of sediment larger than 0.025 mm,43.73% was deposited on the channel,and for inputs of sediments larger than 0.05 mm and larger than 0.10 mm,76.61% and 97.68% were deposited on the channel,respectively.Thus,for reduction of each ton of sediment larger than 0.10 mm from the drainage basin,the resultant reduction in channel sedimentation in the lower Yellow River would be 1.275 times that for the sediment larger than 0.10 mm,and 2.234 times that for the sediment larger than 0.025 mm.Therefore,if the erosion and sediment control measures are enforced in the areas where >0.05 or >0.10 mm sediment is produced,then the best beneficial will be achieved in reducing sedimentation in the lower Yellow River.

  5. Effect of suspended sediment grain size on channel sedimentation in the lower Yellow River and some implications

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on the data of suspended sediment transport and channel sedimentation in various grain size fractions in the period of 1962―1985, the relationship between channel sedimentation in the lower Yellow River and sediment input has been plotted with respect to each grain size fraction. Several fill-scour thresholds in sediment input have been identified from these graphs. It was found that the fill-scour threshold in sediment input decreases with the increase in fraction grain size. The correlation coefficient between channel sedimentation and sediment input becomes larger with the increasing fraction grain size, indicating that channel sedimentation depends more on coarser grain size fractions than on smaller ones. The fraction channel sedimentation induced by unit change of fraction sediment input increases with grain size. Of the input of sediment larger than 0.025 mm, 43.73% was deposited on the channel, and for inputs of sediments larger than 0.05 mm and larger than 0.10 mm, 76.61% and 97.68% were deposited on the channel, respectively. Thus, for reduction of each ton of sediment larger than 0.10 mm from the drainage basin, the resultant reduction in channel sedimentation in the lower Yellow River would be 1.275 times that for the sediment larger than 0.10 mm, and 2.234 times that for the sediment larger than 0.025 mm. Therefore, if the erosion and sediment control measures are enforced in the areas where >0.05 or >0.10 mm sediment is produced, then the best beneficial will be achieved in reducing sedimentation in the lower Yellow River.

  6. Geomorphic Framework to assess changes to aquatic habitat due to flow regulation and channel and floodplain alteration, Cedar River, Washington

    Science.gov (United States)

    Gendaszek, Andrew S.; Magirl, Christopher S.; Czuba, Christiana R.; Konrad, Christopher P.; Little, Rand

    2010-01-01

    Flow regulation, bank armoring, and floodplain alteration since the early 20th century have contributed to significant changes in the hydrologic regime and geomorphic processes of the Cedar River in Washington State. The Cedar River originates in the Cascade Range, provides drinking water to the Seattle metropolitan area, and supports several populations of anadromous salmonids. Flow regulation currently has limited influence on the magnitude, duration, and timing of high-flow events, which affect the incubation of salmonids as well as the production and maintenance of their habitat. Unlike structural changes to the channel and floodplain, flow regulation may be modified in the short-term to improve the viability of salmon populations. An understanding of the effects of flow regulation on those populations must be discerned over a range of scales from individual floods that affect the size of individual year classes to decadal high flow regime that influences the amount and quality of channel and off-channel habitat available for spawning and rearing. We present estimates of reach-scale sediment budgets and changes to channel morphology derived from historical orthoimagery, specific gage analyses at four long-term streamflow-gaging stations to quantify trends in aggradation, and hydrologic statistics of the magnitude and duration of peak streamflows. These data suggest a gradient of channel types from unconfined, sediment-rich segments to confined, sediment-poor segments that are likely to have distinct responses to high flows. Particle-size distribution data and longitudinal water surface and streambed profiles for the 56 km downstream of Chester Morse Lake measured in 2010 show the spatial extent of preferred salmonid habitat along the Cedar River. These historical and current data constitute a geomorphic framework to help assess different river management scenarios for salmonid habitat and population viability. PDF version of a presentation on changes to aquatic

  7. Wandering gravel-bed rivers and high-constructive stable channel sandy fluvial systems in the Ross River area, Yukon Territory, Canada

    Directory of Open Access Journals (Sweden)

    Darrel G.F. Long

    2011-07-01

    Gravel-dominated strata, inter-bedded with, and overlying coal-bearing units, are interpreted as deposits of wandering gravel-bed rivers, with sinuosity approaching 1.4. In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates, which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan. Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures. In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1–5.5 m. These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2–12 m. Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rhône River system. Mudstone preserved in some of the channels reflects intervals of channel abandonment or avulsion. Minimum channel width is from 70 to 450 m.

  8. Dam-induced and natural channel changes in the Saskatchewan River below the E.B. Campbell Dam, Canada

    Science.gov (United States)

    Smith, Norman D.; Morozova, Galina S.; Pérez-Arlucea, Marta; Gibling, Martin R.

    2016-09-01

    The E.B. Campbell Dam on the Saskatchewan River, east-central Saskatchewan, was constructed in 1962, forming Tobin Lake (2.2 billion m3 capacity), which today impounds most fluvial sediment and disrupts normal outflow patterns. Thirty-five kilometers below the dam, the river diverts into a 500 km2 belt of alluvial sediment initiated by an avulsion 140 years ago, rejoining the parent channel 108 km from the dam. Effects of the dam on channel geomorphology, including the historical channel (reach I) and the more recent avulsion-affected channels, were investigated by pre- and post-dam cross section surveys combined with grain-size and bedload measurements. Twenty-three sites were surveyed at least twice, and 14 were resurveyed annually in 2003-2014 (except 2007) during which significant floods occurred in 2005, 2011, and 2013. All channel cross sections up to 81 km below the dam have coarsened and enlarged since closure, resulting in excavation of 35.4 × 106 m3 of channel-perimeter sediment since 1962. The most proximal segment is armored and has changed little in recent years. Since 2003, channel enlargement has been greatest in the 35-81 km segment between the avulsion site and the Forks (reaches II, III), manifested as widening and deepening. Enlargement rates were greatest during the three floods, and the paucity of bedload has prevented degraded portions of the channel bed from replenishment following flooding. Budget calculations based on bedload measurements and channel cross-section areas suggest that > 30 years would be required to replace the sediment removed between 2003 and 2014, assuming all available bedload remains in the affected reach. Dam effects appear to be absent or uncertain beyond 81 km, a multichanneled region of varied stages of activity (reach IV), recombining and eventually rejoining the parent Saskatchewan River channel at km 108 (reach V). Sediment evacuated from reaches I-III is sufficient to sustain modest aggradation in some distal

  9. FLOODPLAIN, JUNIATA COUNTY, USA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Floodplain Mapping/Redelineation study deliverables depict and quantify the flood risks for the study area. The primary risk classifications used are the...

  10. River channel sensitivity to change in the context of human activities and natural factors: an 80-year record of channel morphodynamics on the lower Santa Clara River, Ventura County, California

    Science.gov (United States)

    Downs, P. W.; Dusterhoff, S. R.; Sears, W. A.

    2010-12-01

    River channel adjustments arise from the application of numerous catchment-based stressors operating at different space and time scales. Natural stressors include the impact of climatic phenomena and their inheritance; human stressors include both direct and indirect factors whose impacts have grown in magnitude and intensity during the Anthropocene, especially since about 1945. Consequently, the sensitivity of river channel morphodynamics is likely to have changed also, with implications for landform understanding and river management. Reconstructing channel morphodynamics during the Anthropocene requires interpreting multiple historical and secondary data sources to document changes at sufficient (i.e., reach-scale) resolution: for the 60-km lower Santa Clara River (LSCR), Ventura County, California, we used flow, sediment and precipitation records, repeat aerial photographs, LiDAR data, repeat topographic surveys, in-channel vegetation data, field observations, numerical modeling of high flow events, and narrative accounts. The catchment historical context since European-American settlement includes periods dominated by ranching and colonization (ca.1820-1890), irrigations and diversions (ca.1890-1955), dams and river modifications (1955-1990), and urban population growth (1990-present). Natural stressors were investigated based on the correlation of instantaneous flood peaks with annual rainfall records in this semi-arid setting. Successful prediction of the majority of gauged floods since about 1950 allows a flood sequence to be reconstructed back to 1873. Floods are clustered and of considerably greater magnitude in El Nino years of the El Nino-Southern Oscillation. The great majority of sediment transport thus occurs in El Nino years so that the dominant discharge is the largest discharge on record, in contrast to humid-region alluvial rivers. Responding to these stressors, the average width of the active channel bed has become narrower by almost 50% (1938

  11. The challenges in using UAV and plane imagery to quantify channel change in sandy braided rivers

    Science.gov (United States)

    Strick, Robert; Ashworth, Philip; Best, James; Lane, Stuart; Nicholas, Andrew; Parsons, Daniel; Sambrook Smith, Gregory; Simpson, Christopher; Unsworth, Christopher

    2017-04-01

    The development of numerical models of river morpho-dynamics is hampered by the lack of high-resolution data at multiple time and space scales for model validation. Such data are especially challenging to obtain for sand-bed braided rivers that typically have multiple channels of varying depth and contain rapidly migrating low-relief bar-lobes and dunes. This paper reports on the efforts to meet these challenges using repeat UAV surveys and plane sorties to quantify morphological change and bedform migration rates along the South Saskatchewan River, Canada. The South Saskatchewan River, near Outlook (SK Province) is 600 m wide with very well sorted medium sand (D50 = 0.3 mm) and negligible clay. The Gardiner Dam, 20 km upstream of the study reach, traps much of the very fine sediment so that the waters are clear at low flow and therefore the river bed is entirely visible. Fieldwork campaigns in 2015 and 2016 captured: (i) 1:5000 aerial colour photographs over a 17.5 km reach; (ii) high temporal frequency repeat imagery, obtained using quadcopter and fixed-wing UAV platforms for multiple 100 x 500 m sub-reaches. Plane images were processed via Structure from Motion (SfM) photogrammetric techniques using Pix4D and supporting ArcGIS and Global Mapper analysis. The resulting point cloud was corrected for tilt and filtered in MATLAB at multiple spatial scales to remove noise. Elevations in sub-aqueous zones were obtained using a statistical model, relating image brightness to water depth, developed using single beam echo-sounder data collected near to the flight time. The final DSM for the plane imagery combines these two methods and has a 0.5 m spatial resolution with vertical accuracy of 6 cm. UAV imagery is also processed using Pix4D with application of a diffraction water depth correction, required due to the lower flight height, and gives a resulting vertical accuracy of 2 cm. Initial results highlight the following issues: (i) there are a series of technical

  12. Influence of channel morphology and flow regime on larval drift of pallid sturgeon in the Lower Missouri River

    Science.gov (United States)

    Erwin, Susannah O.; Jacobson, Robert B.

    2015-01-01

    The transition from drifting free embryo to exogenously feeding larvae has been identified as a potential life-stage bottleneck for the endangered Missouri River pallid sturgeon. Previous studies have indicated that river regulation and fragmentation may contribute to the mortality of larval pallid sturgeon by reducing the extent of free-flowing river available to free embryos to complete ontogenetic development. Calculations of total drift distance based on mean velocity, however, do not address the potential for complex channels and flow patterns to increase retention or longitudinal dispersion of free embryos. We use a one-dimensional advection–dispersion model to estimate total drift distance and employ the longitudinal dispersion coefficient as a metric to quantify the tendency towards dispersion or retention of passively drifting larvae. We describe the effects of different styles of channel morphology on larval dispersion and consider the implications of flow regime modifications on retention of free embryos within the Lower Missouri River. The results illustrate the complex interactions of local morphology, engineered structures, and hydraulics that determine patterns of dispersion in riverine environments and inform how changes to channel morphology and flow regime may alter dispersion of drifting organisms.

  13. Response of lateral channel dynamics of a lowland meandering river to engineering-derived adjustments - an example of the Morava River (Czech Republic)

    Science.gov (United States)

    Ondruch, Jakub; Mácka, Zdenek

    2015-11-01

    Freely meandering (quasi)natural reaches of lowland rivers represent a rare phenomenon in Central Europe. Increasing attention is currently being paid to the dynamics of quasi-natural (artificially influenced) meandering rivers as this attention represents the basic prerequisite for the development of appropriate restoration strategies on regulated rivers. This study focused on a 5.5 km long reach of the Morava River in the Strážnické Pomoraví region, Czech Republic that is characterised by quasi-natural evolution after substantial engineering adjustments were made in the first decades of the twentieth century. Based on Geographic Information Systems (GIS) analysis of aerial photographs, the spatio-temporal dynamics of bank erosion and accretion rates were quantitatively described and variables that control channel migration rates were identified. High rates of lateral shifts were localised in high sinuosity segments (sinuosity 1.17-2.37), whereas segments with very low rates were straight or formed into slightly curved bends (sinuosity 1.05-1.18). As a key factor, engineering works that influenced local river bed slope and induced a dramatic increase in bank erosion rates were identified. River engineering works induced a dramatic increase in bank erosion rate (2.19 m/year for 1938-53 and 1.47 m/year for 1953-63). An interval of approximately 25 years was needed before the erosion rates dropped back to values documented before river regulation (0.35-1.09 m/year for 1841-1938). Other important controlling variables included radius of curvature, frequency and magnitude of floods and, locally, river bank material properties and floodplain land cover.

  14. The dynamic feedbacks between channel changes in the Colorado River Basin and the rapid invasion of Tamarisk

    Science.gov (United States)

    Manners, R.; Schmidt, J. C.

    2009-12-01

    The resiliency and sensitivity of western rivers to future climate change may be partly anticipated by the response of these rivers to past perturbations in stream flow and sediment supply. Predictions of earlier spring runoff and reduced peak flows of snowmelt-dominated streams mimic hydrologic changes caused by the closure and operation of large dams built within the past century. In the Colorado River Basin, channels have narrowed between 5 and 26% following large dam construction, but the correlation between flow reduction and channel narrowing is confounded by changes in bank strength caused by the rapid spread of the non-native riparian shrub, tamarisk (Tamarix spp.). Thus, predictions of future changes in channel form and analysis of past changes related to dams must distinguish between channel narrowing caused by direct changes in flow, and caused by the indirect effects wherein changes in flow regime allow expansion of non-native riparian vegetation that in turn leads to accelerated channel narrowing. Our research evaluates the geomorphic controls on tamarisk colonization, the role of tamarisk in accelerating the narrowing process, and the dynamic feedbacks between channel changes on western rivers and the invasion of non-native riparian species. The transformation of formerly active bars and channel margins into stable inset floodplain surfaces is the dominant process by which these channels have narrowed, as determined by detailed alluvial stratigraphy and dendrogeomorphology. We recreated the 3-dimensional bar surface present at the time of tamarisk establishment by excavating an extensive network of trenches. In doing this, we evaluated the hydraulic environment within which tamarisk established. We also characterized the hydrodynamic roughness of aging tamarisk stands from ground-based LiDAR scans to evaluate the role of tamarisk in the promotion of floodplain formation. Our study sites are representative of the predominant geomorphic organization of

  15. Drivers of barotropic and baroclinic exchange through an estuarine navigation channel in the Mississippi River Delta Plain

    Science.gov (United States)

    Snedden, Gregg

    2016-01-01

    Estuarine navigation channels have long been recognized as conduits for saltwater intrusion into coastal wetlands. Salt flux decomposition and time series measurements of velocity and salinity were used to examine salt flux components and drivers of baroclinic and barotropic exchange in the Houma Navigation Channel, an estuarine channel located in the Mississippi River delta plain that receives substantial freshwater inputs from the Mississippi-Atchafalaya River system at its inland extent. Two modes of vertical current structure were identified from the time series data. The first mode, accounting for 90% of the total flow field variability, strongly resembled a barotropic current structure and was coherent with alongshelf wind stress over the coastal Gulf of Mexico. The second mode was indicative of gravitational circulation and was linked to variability in tidal stirring and the horizontal salinity gradient along the channel’s length. Tidal oscillatory salt flux was more important than gravitational circulation in transporting salt upestuary, except over equatorial phases of the fortnightly tidal cycle during times when river inflows were minimal. During all tidal cycles sampled, the advective flux, driven by a combination of freshwater discharge and wind-driven changes in storage, was the dominant transport term, and net flux of salt was always out of the estuary. These findings indicate that although human-made channels can effectively facilitate inland intrusion of saline water, this intrusion can be minimized or even reversed when they are subject to significant freshwater inputs.

  16. Longitudinal dispersion in natural channels: 3. An aggregated dead zone model applied to the River Severn, U.K.

    Directory of Open Access Journals (Sweden)

    P. M. Davis

    2000-01-01

    Full Text Available An Aggregated Dead Zone (ADZ model is presented for longitudinal dispersion of tracer in river channels, in which the channel cross-section is divided into two parallel regions: the bulk flow and dead zone storage. Tracer particles in the bulk flow are assumed to obey plug-flow advection at the discharge velocity U without any mixing effects. The dispersive properties of the model are completely embodied in the residence time for tracer storage in the dead zone. The model provides an excellent description and prediction of empirical concentration-time distributions, for times t Its physical realism is demonstrated by using it to describe the evolution of a tracer cloud in the River Severn, U.K., and by comparing it with a more complex model which incorporates the additional effects of shear flow dispersion within the bulk flow. The ADZ model is a potentially useful tool for practical prediction of dispersion in natural channels. Keywords: Channels; dispersion; dead zones; tracers; River Severn

  17. Drivers of Barotropic and Baroclinic Exchange through an Estuarine Navigation Channel in the Mississippi River Delta Plain

    Directory of Open Access Journals (Sweden)

    Gregg A. Snedden

    2016-04-01

    Full Text Available Estuarine navigation channels have long been recognized as conduits for saltwater intrusion into coastal wetlands. Salt flux decomposition and time series measurements of velocity and salinity were used to examine salt flux components and drivers of baroclinic and barotropic exchange in the Houma Navigation Channel, an estuarine channel located in the Mississippi River delta plain that receives substantial freshwater inputs from the Mississippi-Atchafalaya River system at its inland extent. Two modes of vertical current structure were identified from the time series data. The first mode, accounting for 90% of the total flow field variability, strongly resembled a barotropic current structure and was coherent with alongshelf wind stress over the coastal Gulf of Mexico. The second mode was indicative of gravitational circulation and was linked to variability in tidal stirring and the horizontal salinity gradient along the channel’s length. Tidal oscillatory salt flux was more important than gravitational circulation in transporting salt upestuary, except over equatorial phases of the fortnightly tidal cycle during times when river inflows were minimal. During all tidal cycles sampled, the advective flux, driven by a combination of freshwater discharge and wind-driven changes in storage, was the dominant transport term, and net flux of salt was always out of the estuary. These findings indicate that although human-made channels can effectively facilitate inland intrusion of saline water, this intrusion can be minimized or even reversed when they are subject to significant freshwater inputs.

  18. Effect of the barrage and embankments on flooding and channel avulsion case study Koshi River, Nepal

    NARCIS (Netherlands)

    Devkota, L.; Crosato, A.; Giri, S.

    2012-01-01

    Humans have utilized water resources for millennia by modifying natural river courses and such interventions have greatly influenced not only river flows and sediment fluxes, but also the overall river morphology. Situated in the Nepal's eastern Ganges region, the braided Koshi River is unique among

  19. A multi-scalar approach for modelling river channel change in the Anthropocene

    Science.gov (United States)

    Downs, Peter; Piégay, Hervé; Piffady, Jeremy; Valette, Laurent; Vaudor, Lise

    2017-04-01

    Adjustments in river channel morphology during the 'Anthropocene' arise as a cumulative impact from the influence of numerous natural and human stressors operating at multiple spatial and temporal scales. However, the research requirement for data on impacts at multiple scales, and at sufficiently high spatial and temporal resolution to determine reach-level effect, largely prevented such studies until recent improvements in digital technologies and data availability. A meta-analysis of recent cumulative impact studies indicates that the analytical component is still overwhelmingly interpretative, with cause-and-effect reasoning based largely on temporal synchronicity and spatial proximity, whereas our conceptual understanding of adjustment processes is far more nuanced. We propose, instead, that studies of cumulative impact should be underpinned by an analytical model of cause and effect, partly to test and enhance our predictive capabilities and allow scenario setting, but also to learn about the relative sensitivities involved in different parts of the model and thus to prioritize future research endeavours. Our requirements are that the model should be inherently designed to detect reach-level changes over Anthropocene timescales, be capable of integrating co-existing and hierarchical human and natural pressures on fluvial systems, be able to accommodate time-lagged effects and upstream-downstream connectivity, and be based on an explicit conceptual model that can be refined as our process understanding improves. Bayesian Belief Networks (BBNs) offer some potential in this regard and are becoming an increasingly popular option for dealing with complex, multi-scalar relationships in ecology and other environmental sciences. BBNs consist of a conceptual model of nodes and edges (i.e., graph theory) that qualitatively describe the structure of causal relationships between chains of variables, and a quantitative expression of the relative strength of the

  20. Potential effects of deepening the St. Johns River navigation channel on saltwater intrusion in the surficial aquifer system, Jacksonville, Florida

    Science.gov (United States)

    Bellino, Jason C.; Spechler, Rick M.

    2013-01-01

    The U.S. Army Corps of Engineers (USACE) has proposed dredging a 13-mile reach of the St. Johns River navigation channel in Jacksonville, Florida, deepening it to depths between 50 and 54 feet below North American Vertical Datum of 1988. The dredging operation will remove about 10 feet of sediments from the surficial aquifer system, including limestone in some locations. The limestone unit, which is in the lowermost part of the surficial aquifer system, supplies water to domestic wells in the Jacksonville area. Because of density-driven hydrodynamics of the St. Johns River, saline water from the Atlantic Ocean travels upstream as a saltwater “wedge” along the bottom of the channel, where the limestone is most likely to be exposed by the proposed dredging. A study was conducted to determine the potential effects of navigation channel deepening in the St. Johns River on salinity in the adjacent surficial aquifer system. Simulations were performed with each of four cross-sectional, variable-density groundwater-flow models, developed using SEAWAT, to simulate hypothetical changes in salinity in the surficial aquifer system as a result of dredging. The cross-sectional models were designed to incorporate a range of hydrogeologic conceptualizations to estimate the effect of uncertainty in hydrogeologic properties. The cross-sectional models developed in this study do not necessarily simulate actual projected conditions; instead, the models were used to examine the potential effects of deepening the navigation channel on saltwater intrusion in the surficial aquifer system under a range of plausible hypothetical conditions. Simulated results for modeled conditions indicate that dredging will have little to no effect on salinity variations in areas upstream of currently proposed dredging activities. Results also indicate little to no effect in any part of the surficial aquifer system along the cross section near River Mile 11 or in the water-table unit along the cross

  1. Estimating of suspended sediment loads of rivers in the Seine downstream basin and coastal rivers in Southeastern Channel

    Science.gov (United States)

    Landemaine, Valentin; Cerdan, Olivier; Laignel, Benoit; Fournier, Matthieu; Copard, Yoann

    2014-05-01

    Sediment exports in rivers constitute the essential of materials transfer from the land surface to the ocean and contribute significantly to the transfer of nutrients, pesticides, heavy metals which can affect water quality. Such problems of water pollution are particularly present at the Norman loess plateaus because soil erosion is a frequent phenomena and mudslides are common. In this context, the quantification of sediment load, as well as the short and long term variability analysis are a key component for any sustainable management project of water resources. The quantification of sediment fluxes is based on turbidity, suspended sediment concentrations (SSC) and discharge measurements. These measurements must be made with sufficient high frequency for integrating temporal variability of SSC and flows. However, the cost of a high frequency monitoring limits their use at large scale. In France, discharges are monitored using daily frequency (Banque Hydro), while SSC are measured in monthly or bimonthly frequency under the national water quality survey system (RNB). With these low frequency measurements, an algorithm must be used to reconstruct SSC temporal variability and to estimate a sediment flux. Many estimation algorithms have been developed in recent decades, from the simplest to the most elaborate, but no consensus has been reached on the use of a particular algorithm because of the complexity of SSC-discharge relationship. In this study, the analysis focuses on eight Channel coastal watersheds and nine Seine watersheds in the downstream part. We have a several years of high-frequency measurements on nine watersheds with highly variable area (10 km² to 10,000 km²) and low-frequency measurements for all watersheds. From these data, we compared the statistical performance of eleven algorithms to estimate sediment fluxes conventionally used in the literature. These algorithms are: averaging estimator, ratio estimator, linear interpolation, rating curve

  2. Sediment, water column, and open-channel denitrification in rivers measured using membrane-inlet mass spectrometry

    Science.gov (United States)

    Reisinger, Alexander J.; Tank, Jennifer L.; Hoellein, Timothy J.; Hall, Robert O.

    2016-05-01

    Riverine biogeochemical processes are understudied relative to headwaters, and reach-scale processes in rivers reflect both the water column and sediment. Denitrification in streams is difficult to measure, and is often assumed to occur only in sediment, but the water column is potentially important in rivers. Dissolved nitrogen (N) gas flux (as dinitrogen (N2)) and open-channel N2 exchange methods avoid many of the artificial conditions and expenses of common denitrification methods like acetylene block and 15N-tracer techniques. We used membrane-inlet mass spectrometry and microcosm incubations to quantify net N2 and oxygen flux from the sediment and water column of five Midwestern rivers spanning a land use gradient. Sediment and water column denitrification ranged from below detection to 1.8 mg N m-2 h-1 and from below detection to 4.9 mg N m-2 h-1, respectively. Water column activity was variable across rivers, accounting for 0-85% of combined microcosm denitrification and 39-85% of combined microcosm respiration. Finally, we estimated reach-scale denitrification at one Midwestern river using a diel, open-channel N2 exchange approach based on reach-scale metabolism methods, providing an integrative estimate of riverine denitrification. Reach-scale denitrification was 8.8 mg N m-2 h-1 (95% credible interval: 7.8-9.7 mg N m-2 h-1), higher than combined sediment and water column microcosm estimates from the same river (4.3 mg N m-2 h-1) and other estimates of reach-scale denitrification from streams. Our denitrification estimates, which span habitats and spatial scales, suggest that rivers can remove N via denitrification at equivalent or higher rates than headwater streams.

  3. Estimates of deep percolation beneath native vegetation, irrigated fields, and the Amargosa-River Channel, Amargosa Desert, Nye County, Nevada

    Science.gov (United States)

    Stonestrom, David A.; Prudic, David E.; Laczniak, Randell J.; Akstin, Katherine C.; Boyd, Robert A.; Henkelman, Katherine K.

    2003-01-01

    The presence and approximate rates of deep percolation beneath areas of native vegetation, irrigated fields, and the Amargosa-River channel in the Amargosa Desert of southern Nevada were evaluated using the chloride mass-balance method and inferred downward velocities of chloride and nitrate peaks. Estimates of deep-percolation rates in the Amargosa Desert are needed for the analysis of regional ground-water flow and transport. An understanding of regional flow patterns is important because ground water originating on the Nevada Test Site may pass through the area before discharging from springs at lower elevations in the Amargosa Desert and in Death Valley. Nine boreholes 10 to 16 meters deep were cored nearly continuously using a hollow-stem auger designed for gravelly sediments. Two boreholes were drilled in each of three irrigated fields in the Amargosa-Farms area, two in the Amargosa-River channel, and one in an undisturbed area of native vegetation. Data from previously cored boreholes beneath undisturbed, native vegetation were compared with the new data to further assess deep percolation under current climatic conditions and provide information on spatial variability. The profiles beneath native vegetation were characterized by large amounts of accumulated chloride just below the root zone with almost no further accumulation at greater depths. This pattern is typical of profiles beneath interfluvial areas in arid alluvial basins of the southwestern United States, where salts have been accumulating since the end of the Pleistocene. The profiles beneath irrigated fields and the Amargosa-River channel contained more than twice the volume of water compared to profiles beneath native vegetation, consistent with active deep percolation beneath these sites. Chloride profiles beneath two older fields (cultivated since the 1960?s) as well as the upstream Amargosa-River site were indicative of long-term, quasi-steady deep percolation. Chloride profiles beneath the

  4. Successive impact of tidal bores on sedimentary processes: Arcins channel, Garonne River

    Science.gov (United States)

    Reungoat, David; Leng, Xinqian; Chanson, Hubert

    2017-03-01

    A tidal bore is a hydrodynamic shock, propagating upstream as the tidal flow turns to rising, with macro-tidal conditions in a funnel shaped system with shallow waters. The tidal bore of the Garonne River was extensively investigated in the Arcins channel between 2010 and 2013, typically over one to two days. In 2015, new field measurements were repeated systematically at the same site on 29 August-1 September 2015 and on 27 October 2015. The nature of the observations was comprehensive, encompassing hydrodynamics and turbulence, as well as sediment properties and transport. The tidal bore occurrence had a marked effect on the velocity and suspended sediment field, including a rapid flow deceleration and flow reversal during the bore passage, with very large suspended sediment concentrations (SSCs) during the passage of the tidal bore front and early flood tide, as well as very large suspended sediment flux during the very early flood tide. The suspended sediment concentration (SSC) data indicated a gradual increase in initial mean SSC estimate prior to the bore from 29 August to 1 September 2015. A comparison between suspended sediment flux data showed very significant suspended sediment flux on the first day of tidal bore occurrence, with a decreasing magnitude over the next three days. The data suggested a two-stage bed scour process: at each tidal bore event, surface erosion occurred initially, in the form of stripping; the first stage was followed by delayed mass erosion, occurring about 5-15 min after the tidal bore.

  5. Numerical modeling of sedimentation control scenarios in the approach channel of the Nakdong River Estuary Barrage, South Korea

    Institute of Scientific and Technical Information of China (English)

    Un Ji; Eun-Kyung Jang; Gwonhan Kim

    2016-01-01

    The effects of sedimentation reduction at the Nakdong River Estuary Barrage (NREB) in Korea were quantitatively analyzed with respect to different sediment control methods using the calibrated and validated two-dimensional model. The countermeasures of sediment dredging, sediment flushing, channel geometry change, and a combination of flushing and channel geometry change were examined for the approach channel of the NREB. The flood event and channel geometries of the 3.8 km section upstream of the NREB surveyed before and after dredging in 2007 were used for modeling conditions. As a result, the half of sediments dredged in 2007 could be eliminated naturally by floods without dredging. The numerical simulation of sediment flushing indicated that the deposition height decreased in the entire simulation section with the minimum and maximum reductions from 0.3 m to 1.3 m in deposition height. The channel contraction method produced quantitatively the largest amount of sedimentation reduction and sediment flushing and dredging followed. Sedimentation reduction by a combination of flushing and channel contraction was up 10%compared to the individual method of channel contraction.

  6. Connectivity of Multi-Channel Fluvial Systems: A Comparison of Topology Metrics for Braided Rivers and Delta Networks

    Science.gov (United States)

    Tejedor, A.; Marra, W. A.; Addink, E. A.; Foufoula-Georgiou, E.; Kleinhans, M. G.

    2016-12-01

    Advancing quantitative understanding of the structure and dynamics of complex networks has transformed research in many fields as diverse as protein interactions in a cell to page connectivity in the World Wide Web and relationships in human societies. However, Geosciences have not benefited much from this new conceptual framework, although connectivity is at the center of many processes in hydro-geomorphology. One of the first efforts in this direction was the seminal work of Smart and Moruzzi (1971), proposing the use of graph theory for studying the intricate structure of delta channel networks. In recent years, this preliminary work has precipitated in a body of research that examines the connectivity of multiple-channel fluvial systems, such as delta networks and braided rivers. In this work, we compare two approaches recently introduced in the literature: (1) Marra et al. (2014) utilized network centrality measures to identify important channels in a braided section of the Jamuna River, and used the changes of bifurcations within the network over time to explain the overall river evolution; and (2) Tejedor et al. (2015a,b) developed a set of metrics to characterize the complexity of deltaic channel networks, as well as defined a vulnerability index that quantifies the relative change of sediment and water delivery to the shoreline outlets in response to upstream perturbations. Here we present a comparative analysis of metrics of centrality and vulnerability applied to both braided and deltaic channel networks to depict critical channels in those systems, i.e., channels where a change would contribute more substantially to overall system changes, and to understand what attributes of interest in a channel network are most succinctly depicted in what metrics. Marra, W. A., Kleinhans, M. G., & Addink, E. A. (2014). Earth Surface Processes and Landforms, doi:10.1002/esp.3482Smart, J. S., and V. L. Moruzzi (1971), Quantitative properties of delta channel networks

  7. An overview of historical channel adjustment and selected hydraulic values in the Lower Sabine and Lower Brazos River Basins, Texas and Louisiana

    Science.gov (United States)

    Heitmuller, Franklin T.; Greene, Lauren E.; John D. Gordon, John D.

    2010-01-01

    The Sabine and Brazos are alluvial rivers; alluvial rivers are dynamic systems that adjust their geometry in response to changes in streamflow (discharge) and sediment load. In fluvial geomorphology, the term 'channel adjustment' refers to river channel changes in three geometric dimensions: (1) channel slope (profile); (2) the outline or shape, such as meandering or braided, projected on a horizontal plane (planform); and (3) cross-sectional form (shape). The primary objective of the study was to investigate how the channel morphology of these rivers has changed in response to reservoirs and other anthropogenic disturbances that have altered streamflow and sediment load. The results of this study are expected to aid ecological assessments in the lower Sabine River and lower Brazos River Basins for the Texas Instream Flow Program. Starting in the 1920s, several dams have been constructed on the Sabine and Brazos Rivers and their tributaries, and numerous bridges have been built and sometimes replaced multiple times, which have changed the natural flow regime and reduced or altered sediment loads downstream. Changes in channel geometry over time can reduce channel conveyance and thus streamflow, which can have adverse ecological effects. Channel attributes including cross-section form, channel slope, and planform change were evaluated to learn how each river's morphology changed over many years in response to natural and anthropogenic disturbances. Climate has large influence on the hydrologic regimes of the lower Sabine and lower Brazos River Basins. Equally important as climate in controlling the hydrologic regime of the two river systems are numerous reservoirs that regulate downstream flow releases. The hydrologic regimes of the two rivers and their tributaries reflect the combined influences of climate, flow regulation, and drainage area. Historical and contemporary cross-sectional channel geometries at 15 streamflow-gaging stations in the lower Sabine and

  8. Channel centerline for the Rogue River, Oregon in 1967 and 1969

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Rogue River drains 13,390 square kilometers of southwestern Oregon before flowing into the Pacific Ocean near the town of Gold Beach, Oregon. The Rogue River...

  9. Wetted channel and bar features for the Rogue River, Oregon in 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Rogue River drains 13,390 square kilometers of southwestern Oregon before flowing into the Pacific Ocean near the town of Gold Beach, Oregon. The Rogue River...

  10. Wetted channel and bar features for the Rogue River, Oregon in 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Rogue River drains 13,390 square kilometers of southwestern Oregon before flowing into the Pacific Ocean near the town of Gold Beach, Oregon. The Rogue River...

  11. Wetted channel and bar features for the Rogue River, Oregon in 1967 and 1969

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Rogue River drains 13,390 square kilometers of southwestern Oregon before flowing into the Pacific Ocean near the town of Gold Beach, Oregon. The Rogue River...

  12. Long-term channel adjustment and geomorphic feature creation by vegetation in a lowland, low energy river

    Science.gov (United States)

    Grabowski, Robert; Gurnell, Angela

    2016-04-01

    Physical habitat restoration is increasingly being used to improve the ecological status of rivers. This is particularly true for lowland streams which are perceived to lack sufficient energy to create new features or to flush out fine sediment derived from agricultural and urban sources. However, this study has found that even in low-energy, base-flow dominated chalk streams, physical habitat improvement can happen naturally without direct human intervention. Furthermore this positive change is achieved by components of the river that are often regarded as management problems: in-stream macrophytes (i.e. weed), riparian trees, woody debris, and most importantly fine sediment. This project investigated the long-term changes in channel planform for the River Frome (Dorset, UK) over the last 120 years and the role of aquatic and riparian vegetation in driving this change. Agricultural census data, historical maps, recent aerial images and field observations were analysed within a process-based, hierarchical framework for hydromorphological assessment, developed in the EU FP7 REFORM project, to investigate the source and timing of fine sediment production in the catchment, to quantify the reach-scale geomorphic response, and to identify vegetation-related bedforms that could be responsible for the adjustment. The analysis reveals that the channel has narrowed and become more sinuous in the last 50-60 years. The timing of this planform adjustment correlates with substantial changes in land use and agricultural practices (post-World War II) that are known to increase soil erosion and sediment connectivity. The field observations and recent aerial images suggest that the increased delivery of fine sediment to the channel has been translated into geomorphic adjustment and diversification though the interactions between vegetation, water flow and sediment. Emergent aquatic macrophytes are retaining fine sediment, leading to the development of submerged shelves that aggrade

  13. An exploration of associations between assemblages of aquatic plant morphotypes and channel geomorphological properties within British rivers

    Science.gov (United States)

    Gurnell, A. M.; O'Hare, J. M.; O'Hare, M. T.; Dunbar, M. J.; Scarlett, P. M.

    2010-03-01

    Riparian vegetation, particularly trees and shrubs, can play a crucial role in the construction and turnover of fluvial landforms, but aquatic plants may also act as river ecosystem engineers. Macrophyte and environmental data from 467 British river reaches are used to explore associations between aquatic plant morphotypes and the physical characteristics of the reaches. The abundance of five plant morphotypes (mosses, linear-submerged, patch-submerged, linear emergent, branched emergent) is estimated for each river reach. Cluster analysis is applied to the abundances of the five morphotypes across the 467 reaches to identify six typical assemblages or clusters of the morphotypes. These clusters are found to be associated with statistically significantly different values of seven physical variables (altitude, slope, median annual flood discharge, channel width, mean bed sediment size, percentage cover of sand and silt on the river bed, and unit stream power). Associations between the morphotype clusters and combinations of the physical variables are explored using Canonical Correspondence Analysis and standard slope-discharge-sediment calibre-channel style graphs. Several of the morphotype clusters are discriminated by unit stream power and bed sediment size. In particular, morphotype clusters dominated by emergent and submerged macrophytes are associated with granules, sand, and finer bed sediments and are rarely found where unit stream power exceeds 100 W m - 2 . One cluster characterised by branched emergent species with relatively low cover of submerged morphotypes is confined to sites with unit stream power below 20 W m - 2 ; and another cluster characterised by linear emergents with low cover of submerged morphotypes is associated with particularly extensive, fine bed sediments, suggesting possible smothering of submerged plants. In contrast, mosses reach their highest abundance in two clusters associated with the highest unit stream power and coarsest bed

  14. Powder River: data for cross-channel profiles at 22 sites in southeastern Montana from 1975 through 2012

    Science.gov (United States)

    Moody, John A.; Meade, Robert H.

    2013-01-01

    at the base of the hills and in the far distance on the left side, west of the white ranch buildings. Powder River has no dams or other large-scale human modifications, which, combined with its substantial suspended-sediment load (2-3 million metric tons per year), makes it an optimal outdoor laboratory for studying natural fluvial processes (Moody and Meade, 1990; Hubert, 1993; Moody and others 2002). A research program was started in 1975 and, by 1977, 20 channel cross sections had been established in the 93-km reach, with the uppermost (PR113) just upstream from the Moorhead gage and the lowermost (PR206, see map) just downstream from the Broadus gage. Cross section PR120 crosses the river in this photo at a point near where the shadows from the large cottonwood trees on the left bank meet the river downstream from the apex of the nearer bend (Moody and others 1999; Pizzuto and others, 2008). An extreme flood in 1978 (779 m3 s-1) was a major disturbance that widened the channel, caused two meander cutoffs (not visible in this photo), and deposited fresh sediment on the Lightning and Moorcroft terraces. Two additional cross sections (PR 122A and PR141A) were established on the cutoffs in 1979, and the post-flood response has been monitored at most channel cross sections through 2012. Elevation datum is NGVD29, and all cross-sectional data (1975-1998) also are available in the references listed below.

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

    Science.gov (United States)

    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).

  16. A unifying computational fluid dynamics investigation on the river-like to river-reversed secondary circulation in submarine channel bends

    Science.gov (United States)

    Giorgio Serchi, F.; Peakall, J.; Ingham, D. B.; Burns, A. D.

    2011-06-01

    A numerical model of saline density currents across a triple-bend sinuous submerged channel enclosed by vertical sidewalls is developed. The unsteady, non-Boussinesq, turbulent form of the Reynolds Averaged Navier-Stokes equations is employed to study the flow structure in a quasi-steady state. Recursive tests are performed with axial slopes of 0.08°, 0.43°, 1.5°, and 2.5°. For each numerical experiment, the downstream and vertical components of the fluid velocity, density, and turbulent kinetic energy are presented at four distinct locations within the channel cross section. It is observed that a crucial change in the flow pattern at the channel bends is observed as the axial slope is increased. At low values of the axial slope a typical river-like pattern is found. At an inclination of 1.5°a transition starts to occur. When the numerical test is repeated with an axial slope of 2.5°, a clearly visible river-reversed secondary circulation is achieved. The change in the cross-sectional flow pattern appears to be associated with the spatial displacement of the core of the maximum downstream fluid velocity. Therefore, the axial slope in this series of experiments is linked to the velocity structure of the currents, with the height of the velocity maximum decreasing as a function of increasing slope. As such, the axial slope should be regarded also as a surrogate for flows with enhanced density or sediment stratification and higher Froude numbers. The work unifies the apparently paradoxical experimental and numerical results on secondary circulation in submarine channels.

  17. Comparing the Planform Morphologies of a Freely Meandering Channel and the Bedrock- Controlled South River, VA.

    Science.gov (United States)

    Narinesingh, P.; Pizzuto, J.

    2008-12-01

    The planforms of the lithologically controlled South River, VA, and the freely meandering Teklanika River, AK were investigated using two statistical methods as well as fractal and spectral analyses. The lithologic controls along the South River include riverbanks consisting of pre-Holocene terraces and alluvial fans, and highly resistant bedrock that frequently crops out both in the bed and along the banks. A statistical analysis of bends composed of single arcs shows that the average radius of curvature is six times greater and the average bend length is 25 percent smaller for the South River relative to the meandering river, indicating that lithologically controlled bends are less curved and shorter than freely-formed meander bends. Fractal analysis reveals that the meandering river displays a smaller range in length scales than the South River, which exhibits a wider range in length scales that reflect a wider distribution of bend sizes. The method of Lancaster and Bras, (2002), which identifies bends of different complexity, indicates that the meandering river displays bends composed of single arcs, complex arcs and multiple complex arcs. Unlike the freely meandering Teklanika River, the lithologically controlled South River does not display bends composed of multiple complex arcs, though bends composed of single and complex arcs are common. Spectral analysis reveals that the meandering river's pattern is composed of a relatively narrow range of dominant wavelengths with the most prominent wavelength being the longest, while the lithologically controlled river displays dominant wavelengths over a relatively wide range and the most prominent wavelength is not the longest. This analysis demonstrates that lithological controls increase the range of bend lengths, increase radii of curvature, simplify bend shapes, and increase the distribution of wavelengths of sinuous rivers.

  18. The distribution and extent of declared weeds and invader plants in the macro channel of the Olifants River System, Mpumalanga

    Directory of Open Access Journals (Sweden)

    W.J. Myburgh

    2005-06-01

    Full Text Available The vegetation associated with the macro channel of the Olifants River System was investigated to distinguish plant communities at a spatial scale of 1:250 000. The floristic data were analysed in terms of the sectional and longitudinal distribution and extent of declared weeds and invaders recorded during the survey. The results gained using the PHYTOTAB PC-classification and mapping program package revealed eight Grassland Biome and nine Savanna Biome plant communities from it's origin near the town of Breyten up to the border of the Kruger National Park. It was found that different invader species/weeds are associated with different biomes and habitats along the river system and that an alarming number of these species occur throughout the system.

  19. Mapping spatial patterns of stream power and channel change along a gravel-bed river in northern Yellowstone

    Science.gov (United States)

    Lea, Devin M.; Legleiter, Carl J.

    2016-01-01

    Stream power represents the rate of energy expenditure along a river and can be calculated using topographic data acquired via remote sensing or field surveys. This study sought to quantitatively relate temporal changes in the form of Soda Butte Creek, a gravel-bed river in northeastern Yellowstone National Park, to stream power gradients along an 8-km reach. Aerial photographs from 1994 to 2012 and ground-based surveys were used to develop a locational probability map and morphologic sediment budget to assess lateral channel mobility and changes in net sediment flux. A drainage area-to-discharge relationship and DEM developed from LiDAR data were used to obtain the discharge and slope values needed to calculate stream power. Local and lagged relationships between mean stream power gradient at median peak discharge and volumes of erosion, deposition, and net sediment flux were quantified via spatial cross-correlation analyses. Similarly, autocorrelations of locational probabilities and sediment fluxes were used to examine spatial patterns of sediment sources and sinks. Energy expended above critical stream power was calculated for each time period to relate the magnitude and duration of peak flows to the total volumetric change in each time increment. Collectively, we refer to these methods as the stream power gradient (SPG) framework. The results of this study were compromised by methodological limitations of the SPG framework and revealed some complications likely to arise when applying this framework to small, wandering, gravel-bed rivers. Correlations between stream power gradients and sediment flux were generally weak, highlighting the inability of relatively simple statistical approaches to link sub-budget cell-scale sediment dynamics to larger-scale driving forces such as stream power gradients. Improving the moderate spatial resolution techniques used in this study and acquiring very-high resolution data from recently developed methods in fluvial remote

  20. 长江中游马口-田家镇河段40年来河道演变%Channel changes of the Makou-Tianjiazhen reach in the middle Yangtze River during the past 40 years

    Institute of Scientific and Technical Information of China (English)

    张强; 陈永勤; 姜彤; 李茂田

    2007-01-01

    Quantitative analysis was performed on the filling-scouring process for the river reach within Makou and Tianjiazhen, the middle Yangtze River with the help of GIS and DEM techniques. The research results indicate that the river reach between Makou and Tianjiazhen was dominated by the scouring process, and the magnitude of scouring is increasing over time. The intensity of scouring process is more in the deep and narrower river reach than shallower and wider ones. The river reach in the Makou and Tianjiazhen river knot is in frequent scouring and filling process, however the river reach upper to the Makou and lower to the Tianjiazhen river knot is in moderate scouring and filling process. The river reach just upstream or downstream to the river knot (e.g. Makou and Tianjiazhen river knot in this research) is dominated by filling process and the river reach in the river knot is dominated by the scouring process. Research results indicate no changes in the boundary of the river but the scouring and the filling magnitude in specific river channel is strong. The filling and the scouring process of the study river reach is greatly impacted by the sediments and water from the upstream of the study river reach. The construction of the Three Gorges Dam just upstream to Yichang will cause further decrease of the release of the sediment load to the middle and the lower Yangtze River basin, which will further intensify the scouring process of the river channel in the study river reach.

  1. Controls of channel morphology and sediment concentration on flow resistance in a large sand-bed river: A case study of the lower Yellow River

    Science.gov (United States)

    Ma, Yuanxu; Huang, He Qing

    2016-07-01

    Accurate estimation of flow resistance is crucial for flood routing, flow discharge and velocity estimation, and engineering design. Various empirical and semiempirical flow resistance models have been developed during the past century; however, a universal flow resistance model for varying types of rivers has remained difficult to be achieved to date. In this study, hydrometric data sets from six stations in the lower Yellow River during 1958-1959 are used to calibrate three empirical flow resistance models (Eqs. (5)-(7)) and evaluate their predictability. A group of statistical measures have been used to evaluate the goodness of fit of these models, including root mean square error (RMSE), coefficient of determination (CD), the Nash coefficient (NA), mean relative error (MRE), mean symmetry error (MSE), percentage of data with a relative error ≤ 50% and 25% (P50, P25), and percentage of data with overestimated error (POE). Three model selection criterions are also employed to assess the model predictability: Akaike information criterion (AIC), Bayesian information criterion (BIC), and a modified model selection criterion (MSC). The results show that mean flow depth (d) and water surface slope (S) can only explain a small proportion of variance in flow resistance. When channel width (w) and suspended sediment concentration (SSC) are involved, the new model (7) achieves a better performance than the previous ones. The MRE of model (7) is generally methods developed in this study can be used as an effective surrogate in estimation of flow resistance in the large sand-bed rivers like the lower Yellow River.

  2. Reach-scale channel sensitivity to multiple human activities and natural events: Lower Santa Clara River, California, USA

    Science.gov (United States)

    Downs, Peter W.; Dusterhoff, Scott R.; Sears, William A.

    2013-05-01

    Understanding the cumulative impact of natural and human influences on the sensitivity of channel morphodynamics, a relative measure between the drivers for change and the magnitude of channel response, requires an approach that accommodates spatial and temporal variability in the suite of primary stressors. Multiple historical data sources were assembled to provide a reach-scale analysis of the lower Santa Clara River (LSCR) in Ventura County, California, USA. Sediment supply is naturally high due to tectonic activity, earthquake-generated landslides, wildfires, and high magnitude flow events during El Niño years. Somewhat typically for the region, the catchment has been subject to four reasonably distinct land use and resource management combinations since European-American settlement. When combined with analysis of channel morphological response (quantifiable since ca. 1930), reach-scale and temporal differences in channel sensitivity become apparent. Downstream reaches have incised on average 2.4 m and become narrower by almost 50% with changes focused in a period of highly sensitive response after about 1950 followed by forced insensitivity caused by structural flood embankments and a significant grade control structure. In contrast, the middle reaches have been responsive but are morphologically resilient, and the upstream reaches show a mildly sensitive aggradational trend. Superimposing the natural and human drivers for change reveals that large scale stressors (related to ranching and irrigation) have been replaced over time by a suite of stressors operating at multiple spatial scales. Lower reaches have been sensitive primarily to 'local' scale impacts (urban growth, flood control, and aggregate mining) whereas, upstream, catchment-scale influences still prevail (including flow regulation and climate-driven sediment supply factors). These factors illustrate the complexity inherent to cumulative impact assessment in fluvial systems, provide evidence for a

  3. Recent morphological changes in the Mekong and Bassac river channels, Mekong delta: The marked impact of river-bed mining and implications for delta destabilisation

    Science.gov (United States)

    Brunier, Guillaume; Anthony, Edward J.; Goichot, Marc; Provansal, Mireille; Dussouillez, Philippe

    2014-11-01

    The Mekong delta, in Vietnam, is the world's third largest delta. Densely populated, the delta has been significantly armoured with engineering works and dykes to protect populations and infrastructure from storms, and shrimp farms from saltwater intrusion. Considerable development pressures in Vietnam and in the upstream countries have resulted in the construction of several dams in China and in important channel-bed aggregate extractions especially in Cambodia. The effects of these developments impact the delta dynamics in various ways. In this study, changes in the channel morphology of the Mekong proper and the Bassac, the two main distributaries in the 250 km-long deltaic reach from the Cambodian border to the coast, were analysed using channel depth data for 1998 and 2008. The channels display important and irregular bed changes over the 10-year comparison period, including significant incision and expansion and deepening of numerous pools. The mean depth of both channels increased by more than 1.3 m. Both channels also showed correlative significant bed material losses: respectively 90 million m3 in the Mekong and 110 million m3 in the Bassac over the 10-year period. These important losses over a relatively short period, and weak correlations between bed incision and hydraulic parameters suggest that the marked morphological changes are not in equilibrium with flow and sediment entrainment conditions, and are therefore not related to changes in river hydrology. We claim that aggregate extraction, currently practised on a very large scale in the Mekong delta channels and upstream of the delta, is the main cause of these recent morphological changes. These changes are deemed to contribute actively to rampant bank erosion in the delta as well as to erosion of the Mekong delta shoreline. Other contributory activities include the numerous dykes and embankments. The role of existing dams in bed losses remains unclear in the absence of reliable data on the Mekong

  4. IMPACTS OF FLOOD EVENTS IN COARSE SEDIMENT-PRODUCING AREAS ON CHANNEL SILTATION AND FLUVIAL PROCESS OF THE LOWER YELLOW RIVER

    Institute of Scientific and Technical Information of China (English)

    Ou-yang ZHANG; Xiufu FENG; Jiong-xin XU

    2007-01-01

    The method of multiple regression is used to analyze the influences of flood events from the coarse sediment producing areas on the channel siltation and fluvial process of the lower Yellow River based on the flood events from 1950 to 1985. The results showed that the flood events from the coarse sediment producing areas carry larger amounts of sediment load and coarser particle sizes than from other source areas, which increases deposition in the lower river channel. And there exist good correlations between channel siltation of the lower reaches of the Yellow River and the coming water and sediment of flood events from the coarse sediment producing areas. Through these correlations, the amounts of sediment deposition in the lower river channel could be roughly estimated based on the runoff and sediment load of flood events from the coarse sediment producing areas. The sediment deposition caused the fluvial process. There exists a complex response of channel form change to the coming water and sediment load of flood events from the coarse sediment producing areas. When the sediment concentration is smaller than 200kg/m3, the ratio between wide-depth ratio after flood and wide-depth ratio before flood((B/h)a / (B/h)b) will increase with the increase of the maximum sediment concentration; when the sediment concentration is near 200kg/m3, (B/h)a / (B/h)b reaches the maximum value; and when the sediment concentration reaches the limits of hyperconcentrated flow, (B/h)a / (B/h)b will decrease with the increase of the maximum sediment concentration. Generally, flood events from the coarse sediment producing areas made channel form of the lower Yellow River deeper and narrower, but a large amount of sediment deposition simultaneously occurs. So, the impacts of flood events from the coarse sediment producing areas on the channel of the lower Yellow River are lessened.

  5. Channel-planform evolution in four rivers of Olympic National Park, Washington, U.S.A.: The roles of physical drivers and trophic cascades

    Science.gov (United States)

    East, Amy; Jenkins, Kurt J.; Happe, Patricia J.; Bountry, Jennifer A.; Beechie, Timothy J.; Mastin, Mark C.; Sankey, Joel B.; Randle, Timothy J.

    2016-01-01

    Identifying the relative contributions of physical and ecological processes to channel evolution remains a substantial challenge in fluvial geomorphology. We use a 74-year aerial photographic record of the Hoh, Queets, Quinault, and Elwha Rivers, Olympic National Park, Washington, U.S.A., to investigate whether physical or trophic-cascade-driven ecological factors—excessive elk impacts after wolves were extirpated a century ago—are the dominant controls on channel planform of these gravel-bed rivers. We find that channel width and braiding show strong relationships with recent flood history. All four rivers have widened significantly in recent decades, consistent with increased flood activity since the 1970s. Channel planform also reflects sediment-supply changes, evident from landslide response on the Elwha River. We surmise that the Hoh River, which shows a multi-decadal trend toward greater braiding, is adjusting to increased sediment supply associated with rapid glacial retreat. In this sediment-routing system with high connectivity, such climate-driven signals appear to propagate downstream without being buffered substantially by sediment storage. Legacy effects of anthropogenic modification likely also affect the Quinault River planform. We infer no correspondence between channel geomorphic evolution and elk abundance, suggesting that trophic-cascade effects in this setting are subsidiary to physical controls on channel morphology. Our findings differ from previous interpretations of Olympic National Park fluvial dynamics and contrast with the classic example of Yellowstone National Park, where legacy effects of elk overuse are apparent in channel morphology; we attribute these differences to hydrologic regime and large-wood availability.

  6. Channel-planform evolution in four rivers of Olympic National Park, Washington, U.S.A.: The roles of physical drivers and trophic cascades

    Science.gov (United States)

    East, Amy E.; Jenkins, Kurt J.; Happe, Patricia J.; Bountry, Jennifer A.; Beechie, Timothy J.; Mastin, Mark C.; Sankey, Joel B.; Randle, Timothy J.

    2017-01-01

    Identifying the relative contributions of physical and ecological processes to channel evolution remains a substantial challenge in fluvial geomorphology. We use a 74-year aerial photographic record of the Hoh, Queets, Quinault, and Elwha Rivers, Olympic National Park, Washington, U.S.A., to investigate whether physical or trophic-cascade-driven ecological factors—excessive elk impacts after wolves were extirpated a century ago—are the dominant controls on channel planform of these gravel-bed rivers. We find that channel width and braiding show strong relationships with recent flood history. All four rivers have widened significantly in recent decades, consistent with increased flood activity since the 1970s. Channel planform also reflects sediment-supply changes, evident from landslide response on the Elwha River. We surmise that the Hoh River, which shows a multi-decadal trend toward greater braiding, is adjusting to increased sediment supply associated with rapid glacial retreat. In this sediment-routing system with high connectivity, such climate-driven signals appear to propagate downstream without being buffered substantially by sediment storage. Legacy effects of anthropogenic modification likely also affect the Quinault River planform. We infer no correspondence between channel geomorphic evolution and elk abundance, suggesting that trophic-cascade effects in this setting are subsidiary to physical controls on channel morphology. Our findings differ from previous interpretations of Olympic National Park fluvial dynamics and contrast with the classic example of Yellowstone National Park, where legacy effects of elk overuse are apparent in channel morphology; we attribute these differences to hydrologic regime and large-wood availability.

  7. Age, distribution, and significance within a sediment budget, of in-channel depositional surfaces in the Normanby River, Queensland, Australia

    Science.gov (United States)

    Pietsch, T. J.; Brooks, A. P.; Spencer, J.; Olley, J. M.; Borombovits, D.

    2015-06-01

    We present the results of investigations into alluvial deposition in the catchment of the Normanby River, which flows into Princess Charlotte Bay (PCB) in the northern part of the Great Barrier Reef Lagoon. Our focus is on the fine fraction (expansive flat surface generally referred to as the floodplain. Variously described as benches, bank attached bars or inset or inner floodplains, these more or less flat-lying surfaces within the macro-channel have hitherto received little attention in sediment budgeting models. We use high resolution LiDAR based mapping combined with optical dating of exposures cut into these in-channel deposits to compare their aggradation rates with those found in other depositional zones in the catchment, namely the floodplain and coastal plain. In total 59 single grain OSL dates were produced across 21 stratigraphic profiles at 14 sites distributed though the 24 226 km2 catchment. In-channel storage in these inset features is a significant component of the contemporary fine sediment budget (i.e. recent decades/last century), annually equivalent to more than 50% of the volume entering the channel network from hillslopes and subsoil sources. Therefore, at the very least, in-channel storage of fine material needs to be incorporated into sediment budgeting exercises. Furthermore, deposition within the channel has occurred in multiple locations coincident in time with accelerated sediment production following European settlement. Generally, this has occurred on a subset of the features we have examined here, namely linear bench features low in the channel. This suggests that accelerated aggradation on in-channel depositional surfaces has been in part a response to accelerated erosion within the catchment. The entire contribution of ~ 370 kilotonnes per annum of fine sediment estimated to have been produced by alluvial gully erosion over the last ~ 100 years can be accounted for by that stored as in-channel alluvium. These features therefore can

  8. Wetted channel and bar features for the Nehalem River, Oregon in 1967

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  9. Predicted channel types - Potential for Habitat Improvement in the Columbia River Basin

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Basin-wide analysis of potential to improve tributary habitats in the Columbia River basin through restoration of habitat-forming processes. Identification of...

  10. Wetted channel and bar features for the Coquille River, Oregon 1967

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Coquille River system is an unregulated system that encompasses 2,745 square kilometers of southwestern Oregon and flows into the Pacific Ocean near the town of...

  11. Channel centerline for the Tillamook, Trask, Wilson, Kilchis, and Miami Rivers, Oregon in 1939

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  12. Wetted channel and bar features for the Nehalem River, Oregon in 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  13. Channel centerline for the Tillamook, Trask, Wilson, Kilchis, and Miami Rivers, Oregon in 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  14. Wetted channel and bar features for the Coquille River, Oregon 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Coquille River system is an unregulated system that encompasses 2,745 square kilometers of southwestern Oregon and flows into the Pacific Ocean near the town of...

  15. Channel centerline for the Tillamook, Trask, Wilson, Kilchis, and Miami Rivers, Oregon in 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  16. Wetted channel and bar features for the Coquille River, Oregon 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Coquille River system is an unregulated system that encompasses 2,745 square kilometers of southwestern Oregon and flows into the Pacific Ocean near the town of...

  17. Wetted channel and bar features for the Coquille River, Oregon 1939

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Coquille River system is an unregulated system that encompasses 2,745 square kilometers of southwestern Oregon and flows into the Pacific Ocean near the town of...

  18. Channel centerline for the Tillamook, Trask, Wilson, Kilchis, and Miami Rivers, Oregon in 1967

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  19. Wetted channel and bar features for the Nehalem River, Oregon in 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  20. Wetted channel and bar features for the Nehalem River, Oregon in 1939

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  1. River channel changes due to convergence of debris flow%泥石流入汇对河流河床演变的影响

    Institute of Scientific and Technical Information of China (English)

    梁志勇; 刘峡; 徐永年; 隋忠诚

    2001-01-01

    通过对现有文献资料的总结,探讨了泥石流人汇后随主河水流运动的几种可能形态和运动特点,分析了主河河床的演变情况,并提出按主支流水沙相互作用的大小,将主河河床演变分为弯曲、摆动和急流-深潭3种类型;对不同类型河流河床演变进行了分析,为进行泥石流人汇对主河水流运动与河床演变影响的研究奠定了基础.%China has a vast territory and 2/3 of it is mountainous area. More than 800 counties (about 40% of the total) have recorded debris flows and more than 60 towns were damaged by debris flows. Debris flows cause a damage of about 30 million dollars annually in China.Such disaster usually takes place in the confluence, at which debris flow run into the main river. Debris flow rushes in main stream in different ways according to the interaction between debris flow and the main stream. Debris flow deposits on main channel of the river, or even stop the river when the flow intensity of the debris flow is stronger than the main stream. Otherwise,the main stream would go through by the deposit fan, or even scour the deposit into the lower river.Based upon investigations of fluvial process in mountainous area in China, particularly in which debris flow often occurs, river channel changes due to debris flow are analyzed. Three types of river channels are clarified. The first is called meandering channel, the second is called wagging channel, and the third is called rapids and pools channel. Meandering streams usually meander because of lateral restriction formed by debris flow. Wagging channel often have a wagging watercourse on the channel bed, which is built by the debris flow deposit. Such rivers as the Xiaojiang River and the Jinshajiang River are described. The paper presents their characteristics and mechanism.

  2. Lithologic and hydrologic controls of mixed alluvial-bedrock channels in flood-prone fluvial systems: Bankfull and macrochannels in the Llano River watershed, central Texas, USA

    Science.gov (United States)

    Heitmuller, Franklin T.; Hudson, Paul F.; Asquith, William H.

    2015-03-01

    The rural and unregulated Llano River watershed located in central Texas, USA, has a highly variable flow regime and a wide range of instantaneous peak flows. Abrupt transitions in surface lithology exist along the main-stem channel course. Both of these characteristics afford an opportunity to examine hydrologic, lithologic, and sedimentary controls on downstream changes in channel morphology. Field surveys of channel topography and boundary composition are coupled with sediment analyses, hydraulic computations, flood-frequency analyses, and geographic information system mapping to discern controls on channel geometry (profile, pattern, and shape) and dimensions along the mixed alluvial-bedrock Llano River and key tributaries. Four categories of channel classification in a downstream direction include: (i) uppermost ephemeral reaches, (ii) straight or sinuous gravel-bed channels in Cretaceous carbonate sedimentary zones, (iii) straight or sinuous gravel-bed or bedrock channels in Paleozoic sedimentary zones, and (iv) straight, braided, or multithread mixed alluvial-bedrock channels with sandy beds in Precambrian igneous and metamorphic zones. Principal findings include: (i) a nearly linear channel profile attributed to resistant bedrock incision checkpoints; (ii) statistically significant correlations of both alluvial sinuosity and valley confinement to relatively high f (mean depth) hydraulic geometry values; (iii) relatively high b (width) hydraulic geometry values in partly confined settings with sinuous channels upstream from a prominent incision checkpoint; (iv) different functional flow categories including frequently occurring events (excess of 200 watts per square meter (W/m2); and (vi) downstream convergence of hydraulic geometry exponents for bankfull and macrochannels, explained by co-increases of flood magnitude and noncohesive sandy sediments that collectively minimize development of alluvial bankfull indicators. Collectively, these findings indicate

  3. Three new species of the armored catfish genus Loricaria (Siluriformes: Loricariidae from river channels of the Amazon basin

    Directory of Open Access Journals (Sweden)

    Matthew R. Thomas

    Full Text Available Three new species of Loricaria are described from large white- and black-water river channels of the Amazon basin of Brazil, the upper rio Negro drainage of southern Venezuela, and clear waters of the lower rio Tocantins. Loricaria spinulifera and L. pumila differ from other species of Loricaria by having unique patterns of abdominal plate development and hypertrophied odontodes forming conspicuous crests on dorsal surfaces of the head and predorsal plates. Both are small species of Loricaria, reaching sexual maturity at less than 120 mm SL, and exhibiting sexually dimorphic characters consistent with members of the L. cataphracta complex. Loricaria spinulifera differs from L. pumila in having a unique arrangement of buccal papillae and large thorn-like odontodes on the dorsum of the head. Loricaria pumila is the smallest known Loricaria, reaching sexual maturity at less than 80 mm SL. Loricaria lundbergi differs from other Loricaria by having a unique abdominal plate pattern, broad head, and small basicaudal plate. Loricaria lundbergi is sympatric with L. spinulifera in the lower rio Negro drainage, but is also known from the rio Baria system of the Casiquiare drainage. Loricaria pumila occurs in the lower rio Amazonas and lower rio Tocantins. All three new species exhibit varying degrees of reduction in eye size and pigmentation seen in other fishes inhabiting deep river channels of South America.

  4. Log transport and deposition in incised, channelized, and multithread reaches of a wide mountain river: Tracking experiment during a 20-year flood

    Science.gov (United States)

    Wyżga, Bartłomiej; Mikuś, Paweł; Zawiejska, Joanna; Ruiz-Villanueva, Virginia; Kaczka, Ryszard J.; Czech, Wiktoria

    2017-02-01

    Distance of large wood transport during floods and conditions for wood deposition in wide mountain rivers are still insufficiently understood. Tracking of logs tagged with radio transmitters was used to investigate differences in depositional conditions and the length of log displacement during a 20-year flood between channel reaches of different morphology in the Czarny Dunajec River, Polish Carpathians. During the rising limb of the flood, logs were placed into the river at three locations: at the beginning of an incised reach, close to the beginning of a channelized reach, and 1 km upstream from the beginning of a wide, multithread reach. The incised, channelized, and multithread reaches retained 12.5%, 33%, and 94% of tagged logs introduced to these reaches, respectively, and of the logs retained in the multithread reach, all were deposited in its upstream half. Significant differences in the length of displacement existed between the logs delivered to the river at the three locations, with logs placed into the river at the beginning of the incised reach moving the longest distance, and those delivered just upstream from the multithread reach moving the shortest distance before deposition. One-fourth of the logs were deposited in a low-flow channel or on a channel margin, one-fifth on the floodplain, and more than half on gravel bars. After the flood, river cross sections with deposited logs and a set of cross sections without any wood deposits were surveyed to collect data for one-dimensional modelling of hydraulic conditions at the flood peak. The cross sections with deposited logs were typified by significantly greater flow width and flow area and by significantly smaller mean flow depth, mean velocity, Froude number, mean bed shear stress, and unit stream power. Principal component analysis of the hydraulic parameters in the analysed cross sections grouped the two types of cross sections in distinct clusters, indicating that multithread cross sections

  5. Salmon as drivers of physical and biological disturbance in river channels

    Science.gov (United States)

    Albers, S. J.; Petticrew, E. L.

    2012-04-01

    Large migrations across landscapes and ecosystem boundaries combined with disturbances of riverine spawning habitats through nest construction indicate the huge potential that Pacific salmon (Onchorhynchus sp.) have to disturb and alter regional energy flow. Nutrients derived from ocean-reared dead and decaying salmon are released into surrounding aquatic ecosystems fertilizing the water column, recently disturbed by increased suspended sediments due to nest construction. These opposing forces of disturbance and fertilization on spawning habitat have been demonstrated to impact local geomorphic and ecological cycles within salmon streams. An often cited, yet not fully tested, hypothesis is that this pulse of nutrients provided by decaying salmon can shift freshwater habitats to higher production levels. This hypothesis, however, remains contested and uncertain. Fine sediments are increasingly being recognized as important delivery and storage vectors for marine-derived nutrients (MDNs) in spawning streams. The temporal and spatial significance of these sediment vectors on gravelbed storage of MDN have not been quantified thereby restricting our ability to estimate the impact of gravelbed storage of MDNs on the riverine habitats. The objectives of this study were to i) quantify the magnitude of sediment deposition and retention in an active spawning area and ii) determine the contribution of MDN associated with the fine sediment storage. The Horsefly River spawning channel (HFC), an artificial salmon stock enhancement stream, was used to examine the biogeomorphic impacts of salmon spawning. We organized the HFC in an upstream-downstream paired treatment approach where the upstream enclosure was kept free of salmon and the downstream enclosure was loaded with actively spawning salmon. We used the difference in suspended sediment concentration between the salmon enclosure and the control enclosure to determine the contribution of salmon nest construction to suspended

  6. Suspended sediment transport in the Deepwater Navigation Channel, Yangtze River Estuary, China, in the dry season 2009: 2. Numerical simulations

    Science.gov (United States)

    Song, Dehai; Wang, Xiao Hua

    2013-10-01

    A three-dimensional wave-current-sediment coupled numerical model with wetting and drying process is developed to understand hydrodynamics and sediment transport dynamics in the Deepwater Navigation Channel (DNC), the North Passage of the Yangtze River Estuary (YRE), China. The model results are in good agreement with observed data, and statistics show good model skill scores and correlation coefficients. The model well reproduces the spring-neap variation between a well-mixed estuary and a highly stratified estuary. Model results indicate that the estuarine gravitational circulation plays the most important role in the estuarine turbidity maximum (ETM) formation in the DNC. The upstream nonlocal sediment intrusion through the spillover mechanism is a major source of sediment trapping in the North Passage after the morphological changes. Numerical studies are conducted to show scenarios in the YRE under the effects of different forcings (river discharges, waves, and winds). Between these study cases, surface-wave-breaking relieves the sediment trapping and bottom-wave-current-interaction aggravates the bed erosion and elevates the SSC in the ETM; the former and the latter have the least and largest influence on the suspended sediment transport in the DNC. The wind effects have a greater influence on sediment trapping than the river discharges, and the steady northwesterly wind condition favors the siltation in the DNC most. The significance of density-driven turbidity current is also assessed, which can enhance the saline-water intrusion and suppress the turbulent mixing in the bottom boundary layer.

  7. Sediment Dynamics Affecting the Threatened Santa Ana Sucker in the Highly-modified Santa Ana River and Inset Channel, Southern California, USA

    Science.gov (United States)

    Minear, J. T.; Wright, S. A.

    2015-12-01

    In this study, we investigate the sediment dynamics of the low-flow channel of the Santa Ana River that is formed by wastewater discharges and contains some of the last remaining habitat of the Santa Ana Sucker (Catostomus santaanae). The Santa Ana River is a highly-modified river draining the San Bernardino Mountains and Inland Empire metropolitan area east of Los Angeles. Home to over 4 million people, the watershed provides habitat for the federally-threatened Santa Ana Sucker, which presently reside within the mainstem Santa Ana River in a reach supported by year-round constant discharges from water treatment plants. The nearly constant low-flow wastewater discharges and infrequent runoff events create a small, approximately 8 m wide, inset channel within the approximately 300 m wide mainstem channel that is typically dry except for large flood flows. The sediment dynamics within the inset channel are characterized by constantly evolving bed substrate and sediment transport rates, and occasional channel avulsions. The sediment dynamics have large influence on the Sucker, which rely on coarse-substrate (gravel and cobble) for their food production. In WY 2013 through the present, we investigated the sediment dynamics of the inset channel using repeat bathymetric and substrate surveys, bedload sampling, and discharge measurements. We found two distinct phases of the inset channel behavior: 1. 'Reset' flows, where sediment-laden mainstem discharges from upstream runoff events result in sand deposition in the inset channel or avulse the inset channel onto previously dry riverbed; and 2. 'Winnowing' flows, whereby the sand within the inset channel is removed by clear-water low flows from the wastewater treatment plant discharges. Thus, in contrast to many regulated rivers where high flows are required to flush fine sediments from the bed (for example, downstream from dams), in the Santa Ana River the low flows from wastewater treatment plants serve as the flushing

  8. Analysis of river channel evolution of Modaomen channel of Xijiang River in past forty years%近四十年西江磨刀门水道河床演变分析

    Institute of Scientific and Technical Information of China (English)

    刘锋; 田向平; 韩志远; 蔡华阳

    2011-01-01

    Quantitative analysis of the characteristics of evolution of the Modaomen channel of the Xijiang River China in the past 40 years is performed with the help of DEM.The Modaomen channel was divided longitudinally into three small sections.Three pieces of charts of the Modaomen channel in 1962,1977 and 1999 were digitized respectively and the digital elevation models (DEM) of the Modaomen channel in different periods were established with Kringing gridding method.Based on them, the evolution pattern of the fiver channel as well as the reasons of the evolution is analyzed.The result indicates that the Modaomen channel experienced an obvious switch from deposition to erosion around 1977.From 1962 to 1977 ,the general trend was deposition,and the total deposition volume was 9.92 × 106m3, what's more, the upper channel became narrower and deeper and the lower channel became wider and shallower.From 1977 to 1999, the general treand was erosion, and the total erosion volume was 22.53 × 106m3, additionally, the mean water depth of the channel increased and the channel turned out to be narrower and deeper.The evolution of the Modaomen channel was influenced by the change of natural fiver environment and human activities, but the latter was more important.%将西江磨刀门水道1962、1977、1999年的河道地形图数字化,建立磨刀门水道三个年份的水下数字高程模型(DEM),在此基础上将河道分为上、中、下三段进行了河床演变及其成因分析.结果表明:磨刀门水道1977年前后河道发生过明显的河道冲淤转化;1962年至1977年磨刀门水道处于淤积状态,淤积量达9.92 ×106 m3,河道上游向窄深发展,下游则向宽浅演变;而从1977至1999年磨刀门水道则处于冲刷状态,冲刷量为25.53×106 m3,河道平均水深增加,逐渐向窄深演变.磨刀门水道河床演变是自然环境变化和人类活动共同作用的结果,其中人类活动的影响最为强烈.

  9. Habitat Dynamics in Side-channel Chutes, Lower Missouri River: Progress Report - January 15, 2004

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This progress report summarizes hydrologic and geomorphic monitoring of four side-channel chutes at Lisbon Bottom and Overton Bottoms. Measuring, monitoring, and...

  10. Comparative Evaluation of Hyperspectral Imaging and Bathymetric Lidar for Measuring Channel Morphology Across a Range of River Environments

    Science.gov (United States)

    Legleiter, C. J.; Overstreet, B. T.; Glennie, C. L.; Pan, Z.; Fernandez-Diaz, J. C.; Singhania, A.

    2014-12-01

    Reliable topographic information is critical to many applications in the riverine sciences. Quantifying morphologic change, modeling flow and sediment transport, and assessing aquatic habitat all require accurate, spatially distributed measurements of bed elevation. Remote sensing has emerged as a powerful tool for acquiring such data, but the capabilities and limitations associated with various remote sensing techniques must be evaluated systematically. In this study, we assessed the potential of hyperspectral imaging and bathymetric LiDAR for measuring channel morphology across a range of conditions in two distinct field sites: the clear-flowing Snake River in Grand Teton National Park and the confluence of the Blue and Colorado Rivers in north-central Colorado, USA. Field measurements of water column optical properties highlighted differences among these streams, including the highly turbid Muddy Creek also entering the Colorado, and enabled theoretical calculations of bathymetric precision (smallest detectable change in depth) and dynamic range (maximum detectable depth). Hyperspectral imaging can yield more precise depth estimates in shallow, clear water but bathymetric LiDAR could provide more consistent performance across a broader range of depths. Spectrally-based depth retrieval was highly accurate on the Snake River but less reliable in the more complex confluence setting. Stratification of the Blue/Colorado site into clear and turbid subsets did not improve depth retrieval performance. To obtain bed elevations, image-derived depth estimates were subtracted from water surface elevations derived from near-infrared LiDAR acquired at the same time as the hyperspectral images. For the water-penetrating green LiDAR, bed elevations were inferred from laser waveforms. On the Snake River, hyperspectral imaging resulted in smaller mean and root mean square errors than bathymetric LiDAR, but at the Blue/Colorado site the optical approach was subject to a shallow

  11. Massive biomass flushing despite modest channel response in the Rayas River following the 2008 eruption of Chaitén volcano, Chile

    Science.gov (United States)

    Ulloa, Héctor; Iroumé, Andrés; Picco, Lorenzo; Korup, Oliver; Lenzi, Mario Aristide; Mao, Luca; Ravazzolo, Diego

    2015-12-01

    The 2008 eruption of Chaitén volcano in southern Chile severely impacted several densely forested river catchments by supplying excess pyroclastic sediment to the channel networks. Our aim is to substantiate whether and how channel geometry and forest stands changed in the Rayas River following the sudden input of pyroclastic sediment. We measured the resulting changes to channel geometry and riparian forest stands along 17.6 km of the impacted gravel-bed Rayas River (294 km2) from multiple high-resolution satellite images, aerial photographs, and fieldwork to quantify yield volume characteristics of the forest stands. Limited channel changes during the last 60 years before the eruption reflect a dynamic equilibrium condition of the river corridor, despite the high annual precipitation and the sediment supply from Chaitén and Michinmahuida volcanoes in the headwaters. Images taken in 1945, 2004, and 2005 show that total size of the vegetated channel islands nearly doubled between 1945 and 2004 and remained unchanged between 2004 and 2005. Pyroclastic sediment entering the Rayas River after the 2008 eruption caused only minor average channel widening (7%), but killed all island vegetation in the study reach. Substantial shifts in the size distribution of in-channel vegetation patches reflect losses in total island area of 46% from 2005 to 2009 and an additional 34% from 2009 to 2012. The estimated pulsed release of organic carbon into the channel, mainly in the form of large wood from obliterated island and floodplain forests, was 78-400 tC/km/y and surpasses most documented yields from small mountainous catchments with similar rainfall, forest cover, and disturbance history, while making up between 20% and 60% of the annual carbon burial rate of fluvial sediments in the northern Patagonian fjords. We conclude that the carbon footprint of the 2008 Chaitén eruption on the Rayas River was more significant than the measured geomorphic impacts on channel geometry for

  12. Denitrification capacity and greenhouse gas emissions of soils in channelized and restored reaches along an Alpine river corridor

    Science.gov (United States)

    Shrestha, Juna; Niklaus, Pascal; Samaritani, Emanuela; Frossard, Emmanuel; Tockner, Klement; Luster, Jörg

    2010-05-01

    In order to assess the effects of river restoration on water and air quality, the biogeochemical functions of channelized and restored river reaches have to be quantified. The objective of this study was to compare denitrification potential and greenhouse gas emissions of functional processing zones (FPZ) in a channelized and a recently restored reach of the alpine river Thur in north-eastern Switzerland. The study was part of the project cluster RECORD of the ETH domain, Switzerland, which was initiated to increase the mechanistic understanding of coupled hydrological and ecological processes in river corridors. The denitrification potential represents an important aspect of the soil filter function related to water quality. Besides, it also contributes to the emission of greenhouse gases. Extensively used pasture growing on a sandy loam is the characteristic FPZ of the channelized section. The restored section encompasses five FPZ: (i) bare gravel bars sparsely colonized by plants, (ii) gravel bars densely colonized by grass (mainly canary reed grass with up to 80 cm sandy deposits), (iii) mixed forest dominated by ash and maple, (iv) riparian forest dominated by willow (Salix alba), (v) older overbank sediments stabilized during restoration with young willows separating the forests from the river-gravel bar system (willow bush). The FPZ were sampled in January, April, August and October 2009. In addition, in June and July 2009 two flood events were monitored in the restored section with more frequent samplings. At each date, topsoil samples were collected in each FPZ (four replicates per samples) and analyzed for denitrifier enzyme activity (DEA). In addition, gas samples were taken in-situ using the closed chamber technique to measure soil respiration as well as N2O and CH4 fluxes. In all FPZ, the denitrification potential was mainly governed by soil moisture. It was highest in the willow forest exhibiting low spatial variability. The DEA in pasture, grass zone

  13. Path Loss Channel Model for Inland River Radio Propagation at 1.4 GHz

    Directory of Open Access Journals (Sweden)

    Junyi Yu

    2017-01-01

    Full Text Available In this paper, a propagation path loss model for inland river is proposed by three improvements compared with the Round Earth Loss (REL model for open-sea environment. Specifically, parameters optimization uses Okumura-Hata model in dB scale to replace the equation transformed from the free space loss in REL model; secondly, diffraction loss caused by the obstacles (e.g., large buildings, bridges, or some other facilities near the river bank is also taken into account; mixed-path methodology as another improvement is used for Inland River (IR model because the actual propagation environment between transmitter (TX antenna and receiver (RX antenna contains both land part and water part. The paper presents a set of 1.4 GHz measurements conducted along the Yangtze River in Wuhan. According to the comparison between path loss models and experimental results, IR model shows a good matching degree. After that, Root Mean Square Error (RMSE, Grey Relation Grade and Mean Absolute Percentage Error (GRG-MAPE, Pearson Correlation Coefficient, and Mean Absolute Percentage Error (PCC-MAPE are employed to implement quantitative analysis. The results prove that IR model with consideration of mixed path and deterministic information is more accurate than other classic empirical propagation models for these scenarios.

  14. Channel Morphology and Bed Sediment Characteristics Before and After Habitat Enhancement Activities in the Uridil Property, Platte River, Nebraska, Water Years 2005-2008

    Science.gov (United States)

    Kinzel, Paul J.

    2009-01-01

    Fluvial geomorphic data were collected by the United States Geological Survey from July 2005 to June 2008 (a time period within water years 2005 to 2008) to monitor the effects of habitat enhancement activities conducted in the Platte River Whooping Crane Maintenance Trust's Uridil Property, located along the Platte River, Nebraska. The activities involved the removal of vegetation and sand from the tops of high permanent islands and the placement of the sand into the active river channel. This strategy was intended to enhance habitat for migratory water birds by lowering the elevations of the high islands, thereby eliminating a visual obstruction for roosting birds. It was also thought that the bare sand on the lowered island surfaces could serve as potential habitat for nesting water birds. Lastly, the project supplied a local source of sediment to the river to test the hypothesis that this material could contribute to the formation of lower sandbars and potential nesting sites downstream. Topographic surveys on the islands and along river transects were used to quantify the volume of removed sand and track the storage and movement of the introduced sand downstream. Sediment samples were also collected to map the spatial distribution of river bed sediment sizes before and after the management activities. While the project lowered the elevation of high islands, observations of the sand addition indicated the relatively fine-grained sand that was placed in the active river channel was rapidly transported by the flowing water. Topographic measurements made 3 months after the sand addition along transects in the area of sediment addition showed net aggradation over measurements made in 2005. In the year following the sand addition, 2007, elevated river flows from local rain events generally were accompanied by net degradation along transects within the area of sediment addition. In the spring of 2008, a large magnitude flow event of approximately 360 cubic meters per

  15. The effect of controlled floods on decadal-scale changes in channel morphology and fine sediment storage in a debris-fan affected river canyon

    Science.gov (United States)

    Mueller, E. R.; Grams, P. E.; Schmidt, J. C.

    2013-12-01

    In 2011, a large magnitude flow release from Flaming Gorge Reservoir resulted in the third highest recorded discharge of the Green River downstream from Flaming Gorge Dam subsequent to its closure in 1963. Following this event, we made measurements of channel geometry, tracer gravel displacement, and sandbar sedimentology at four long-term monitoring reaches within the Canyon of Lodore in Dinosaur National Monument, Colorado. Here we integrate these data with nearly two decades of channel monitoring at these sites, encompassing five controlled floods, and providing a coarse resolution, but coherent, picture of channel response and changes in fine sediment storage in a canyon-bound river. We discuss these results in the context of long-term monitoring of controlled flood response along the Colorado River in Marble and Grand Canyons, Arizona. In Canyon of Lodore, moderate, short-duration controlled floods have had little effect on channel morphology or fine sediment storage. Alternatively, higher magnitude floods approaching the pre-dam mean annual flood, such as in 1999 and 2011, tended to be long duration and scoured fine sediment from the channel bed, in some places up to 5 m, while building eddy sandbars to within a meter of flood stage. This resulted in a net export of sediment from the monitored reaches. Between floods, eddy sand bars erode and the pools fill with fine sediment. We have observed only minor erosion or reworking of gravel bars and channel margin deposits stabilized by vegetation encroachment. The Green River in Canyon of Lodore is a scaled-down version of the Colorado River in debris fan-affected Marble and Grand Canyons. Both rivers now exist in varying degrees of sediment deficit due to upstream reservoirs. Coarse sediment from debris fans and hillslopes limits vertical incision and channel migration, focusing the post-dam geomorphic response to sediment imbalance on fine sediment located in eddy sandbars, pools, and channel margin deposits. In

  16. The impacts of ski slope development on stream channel morphology in the White River National Forest, Colorado, USA

    Science.gov (United States)

    David, Gabrielle C. L.; Bledsoe, Brian P.; Merritt, David M.; Wohl, Ellen

    2009-02-01

    The combined influence of tree-clearing, road construction, snowmaking, and machine-grading can cause increased flow and sediment loads along streams in or adjacent to commercial ski resorts. These changes to stream channels can increase bank failures, bed material size, pool scour, and, in extreme cases, channel incision. We used field data from the White River National Forest in Colorado, which includes several major ski resorts, to test the hypothesis that ski slope development causes a significant difference in bank stability, undercut banks, fine sediment, wood load, pool residual depth, and particle size ( D84) between the ski area project streams and reference streams. We further hypothesize that the changes in a stream are mitigated by the density and type of vegetation growing along the banks. A significant difference is defined as a project stream that is outside the range of variability of the reference streams. To test these hypotheses, we surveyed channel conditions, channel dimensions, and vegetation along 47 stream reaches (200-300 m in length). Twenty-four of these streams are within ski areas (project streams), either adjacent to or downstream from ski slopes. Twenty-three reference streams with very little to no development in their basins are used to define reference conditions of bank stability, bank undercutting, bank height, wood load, pool residual depth, sediment size, and vegetation structure. A combination of statistical techniques, including Principal Components Analysis and Classification and Regression Tree Analysis, was used to assess the controls on stream channel morphology and to analyze the differences between project and reference streams. Project streams that are significantly different than reference streams have a combination of a higher percentage of fine sediment, smaller pool residual depth, and higher percentage of unstable banks. The impacted project streams have bed material derived from granitic rocks and a lower density

  17. Causes and typical control model of wind-drift sandy lands in abandoned channel of the Yellow River

    Institute of Scientific and Technical Information of China (English)

    Zhang Guo-zhen; Yang Li; Xu Wei; Sun Bao-ping

    2006-01-01

    The historical formation and development of the abandoned channel of the Yellow River is reviewed and its causes of formation and present condition of prevention and control are analyzed in this paper. Based on this analysis, some ideas about control,critical problems and countermeasures in the next period are proposed with two typical control models as examples. We suggest that in preventing and controlling the wind-drift sandy lands in the region, the emphasis should be to develop, with a greatly expanded effort, a recycling economy. This should realize a combination of two ideas, i.e. integrate combating desertification with a structural adjustment of agricultural and an increase in the income of farmers.

  18. Development of a channel classification to evaluate potential for cottonwood restoration, lower segments of the Middle Missouri River, South Dakota and Nebraska

    Science.gov (United States)

    Jacobson, Robert B.; Elliott, Caroline M.; Huhmann, Brittany L.

    2010-01-01

    This report documents development of a spatially explicit river and flood-plain classification to evaluate potential for cottonwood restoration along the Sharpe and Fort Randall segments of the Middle Missouri River. This project involved evaluating existing topographic, water-surface elevation, and soils data to determine if they were sufficient to create a classification similar to the Land Capability Potential Index (LCPI) developed by Jacobson and others (U.S. Geological Survey Scientific Investigations Report 2007–5256) and developing a geomorphically based classification to apply to evaluating restoration potential.Existing topographic, water-surface elevation, and soils data for the Middle Missouri River were not sufficient to replicate the LCPI. The 1/3-arc-second National Elevation Dataset delineated most of the topographic complexity and produced cumulative frequency distributions similar to a high-resolution 5-meter topographic dataset developed for the Lower Missouri River. However, lack of bathymetry in the National Elevation Dataset produces a potentially critical bias in evaluation of frequently flooded surfaces close to the river. High-resolution soils data alone were insufficient to replace the information content of the LCPI. In test reaches in the Lower Missouri River, soil drainage classes from the Soil Survey Geographic Database database correctly classified 0.8–98.9 percent of the flood-plain area at or below the 5-year return interval flood stage depending on state of channel incision; on average for river miles 423–811, soil drainage class correctly classified only 30.2 percent of the flood-plain area at or below the 5-year return interval flood stage. Lack of congruence between soil characteristics and present-day hydrology results from relatively rapid incision and aggradation of segments of the Missouri River resulting from impoundments and engineering. The most sparsely available data in the Middle Missouri River were water

  19. Columbia River Channel Improvement Project: Final Supplemental Integrated Feasibility Report and Environmental Impact Statement

    Science.gov (United States)

    2003-01-01

    E ATTN: Robert Willis Attention: Judy Grigg P.O. Box 2946, Portland, OR 97208-2946 P.O. Box 1258, Longview, WA 98632-7739 Phone: (503) 808...the origin of many exotic species that could invade the Columbia River, the Chinese mitten crab, zebra mussel and Eurasian milfoil are known...found for their control. Transferred to the U.S. in ballast water and on the hulls of vessels, zebra mussels have caused great environmental and

  20. 78 FR 33219 - Special Local Regulations; Swim Across the Potomac, Potomac River; National Harbor Access Channel...

    Science.gov (United States)

    2013-06-04

    ... INFORMATION: Table of Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed... Access Channel, MD'' in the Federal Register (78 FR 67). We received no comments on the proposed rule. No... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations; Swim Across the...

  1. On ecological treatment strategies of water environment in urban river channels%城市河道的水环境生态治理对策分析

    Institute of Scientific and Technical Information of China (English)

    马哲

    2016-01-01

    From the main problems in the water environment of urban river channels,the paper analyzes its technical status of the urban river channel treatment according to the treatment principle of the urban river channel,and points out related policies from the treatment planning,rain sewage diversion,and integral management,so as to improve the water quality of river channels,and enhance the benign development of water environment in cities.%从河道水环境存在的主要问题入手,根据城市河道的治理原则,分析了当前城市河道治理的技术现状,并从整治规划、雨污分流处理、一体化管理等方面,提出了水环境生态治理的相关对策,从而改善河道水质,促进城市水环境的良性发展。

  2. Side Channels of the Impounded and Middle Mississippi River: Opportunities and Challenges to Maximize Restoration Potential

    Science.gov (United States)

    2016-07-01

    work if the system were intact). The FUIGA was developed based on a monitoring (i.e., measurement and assessment) perspective because most of the... framework for an ecosystem integrity report card. BioSciences 49(7):543–556. Jacobson, R. B., and J. Berkley. 2011. Conceptualizing and communicating...was held in Cape Girardeau, MO, from 10–12 January 2011. The goal of the workshop was to develop conceptual models (CMs) to guide side channel

  3. Sand dynamic in the Mekong River channel and export to the coastal ocean

    Science.gov (United States)

    Stephens, J. D.; Allison, M. A.; Di Leonardo, D. R.; Weathers, H. D.; Ogston, A. S.; McLachlan, R. L.; Xing, F.; Meselhe, E. A.

    2017-09-01

    Two field campaigns were conducted in the tidal and estuarine reach of the Sông Hậu distributary of the Mekong River to explore the dynamics of sand transport and export to the coastal ocean. This study examines variations in suspended sand concentration and net flux of suspended and bedload sand with respect to changes in discharge between the October 2014 high discharge and March 2015 low discharge season. Isokinetic measurements of suspended sand were used to calibrate a larger dataset of LISST profiles to report suspended sand mass concentrations. During the high discharge season, ebb and flood currents are a primary control on suspended sand concentrations. Ebb tidal flows are more capable of sand transport than flooding flows, due to river discharge augmenting tidal currents. Sand in suspension is primarily derived locally from bed material sand. Bedform transport estimates were limited, but suggest that bedload sand transport is less than 10% of net suspended sand flux. Very low concentrations of suspended sand sediment are found during the low discharge season. These low concentrations are likely caused by (1) a reduction in maximum ebb tide shear stresses associated with less freshwater input, and (2) mud mantling in the bed associated with upstream migration of estuarine circulation, that inhibits local sourcing (resuspension) of bed sand. Results of the observational study were used to calibrate a numerical model of annual sand flux to the ocean from all distributaries of the Mekong River. Annual sand export is estimated at 6.5 ± 1.6 Mt yr-1. The Định An subdistributary accounts for 32% of this total while the smaller Trần Đề subdistributary accounts for only 9%.

  4. Carbon and Manganese Cycling in the Columbia River's Estuarine Turbidity Maxima in the South Channel

    Science.gov (United States)

    Bräuer, S. L.; Kranzler, K.; Tebo, B. M.

    2007-12-01

    The Columbia River represents the largest input (60-90%) of fresh water to the California Current System, and provides a major source of dissolved manganese and nutrients to the coastal waters. Researchers have identified upper Estuarine Turbidity Maxima (ETM(s)) as hot spots for microbial activity, and it is here that extensive manganese cycling is thought to occur. Most probable number counts of microorganisms within the ETM have revealed that the cultivable numbers of manganese-oxidizing bacteria are not statistically significantly different than that of other heterotrophs when grown on defined media with simple carbon sources or low concentrations (0.05%) of casamino acids and were in the range of 103 - 104 cells per mL. Similar numbers of heterotrophs (9.3 X 103 cells/mL) were found using a nutrient-rich complex medium; however, the numbers of manganese-oxidizers were significantly lower (~13 cells/mL). Approximately 100 different manganese-oxidizing bacteria were isolated from different media and are being phylogenetically characterized. Measurements of dissolved, ascorbate-reducible and total Mn by inductively coupled plasma- optical emission spectroscopy revealed that concentrations of Mn are positively correlated with turbidity and thus are higher during an ETM event. In addition, dissolved, total, and ascorbate-reducible Mn were all negatively correlated with salinity, supporting the idea that the manganese originates in the river and is diluted by the seawater originating off the coast. Uptake of 14C-labeled bicarbonate in response to various electron donors (nitrite, ammonium, thiosulfate, or Mn(II)) was stimulated during an ETM event but not before or after, indicating that these electron donors may serve as potential energy sources for carbon fixation. Taken together, our results further demonstrate that ETMs are zones with high microbial activity and that the ETM microbial communities harbor the potential for carbon fixation even in the relatively

  5. The influence of sandstone caprock material on bedrock channel steepness within a tectonically passive setting: Buffalo National River Basin, Arkansas, USA

    Science.gov (United States)

    Thaler, E. A.; Covington, M. D.

    2016-09-01

    Bedrock channel profile analysis typically assumes that channels evolve toward a condition of topographic steady state where channel morphology is adjusted to rock erodibility, uplift rates, and stream power. Here we use the integral method of channel profile analysis to quantify channel steepness within a large set of tributary channels that incise through layered rocks in the Buffalo National River Basin in northern Arkansas. Statistical analysis of these channels demonstrates that normalized channel steepness is not a function of local bedrock lithology but is influenced by coarse sediment supply. Specifically, normalized steepness is greatest in reaches of the basin where an interval of Pennsylvanian sandstone forms a caprock on the ridges. Block detachment of the sandstone causes large boulders to be stranded in the upper tributaries where stream power is too low to mobilize or effectively erode the boulders. Within these channels, normalized steepness is correlated with sandstone boulder size and percent boulder coverage rather than local lithology, despite strong contrasts in the mechanical strength of the lithologies incised. This analysis suggests that removal of caprock material is rate limiting within the landscape and may be responsible for the long-term persistence of topography within this tectonically passive setting.

  6. Floodplain deposits, channel changes and riverbank stratigraphy of the Mekong River area at the 14th-Century city of Chiang Saen, Northern Thailand

    Science.gov (United States)

    Wood, Spencer H.; Ziegler, Alan D.; Bundarnsin, Tharaporn

    2008-10-01

    Riverbank stratigraphy and paleochannel patterns of the Mekong River at Chiang Saen provide a geoarchaeological framework to explore for evidence of Neolithic, Bronze-age, AD 5th Century Yonok and AD 14-16th Century Lan Na Cultures. Typical bank stratigraphy charted on the Thailand side is imbricate cobble gravel overlain by 5-10 m of reddish-brown sandy silt. The silt section is composed chiefly of 1/2 to 2-m thick layers of massive silt without paleosols interpreted as near-channel floodplain and gently-inclined levee deposits laid down by episodic, infrequent, large floods. The surface soil is dark-brown clay loam (pottery shards and charcoal of Lan Na time. Brick ruins of 14-16th Century Buddhist temples are crumbling into the river at Chiang Saen Noi, and formerly did so at Chiang Saen until banks were stabilized by rock walls. Bank retreat from river erosion has been > 20 m since Lan Na time, and has exposed a silt-filled moat. A radiocarbon age of 1475 cal yr AD was obtained from charcoal at the bottom of the moat, beneath 5.6 m of silt. Lag material from erosion of the silt banks contains Neolithic and Bronze Age artifacts out of stratigraphic context, as well as ceramics and bricks of Lan Na age. These artifacts as well Neolithic artifacts obtained from a 1972 excavation near the mouth of the Kham River indicate long human habitation of this riverbank area. In northern Thailand the Mekong is mostly in a bedrock canyon, but shifting topography along the active strike-slip Mae Chan fault has formed the upstream 2-5-km wide floodplain at Chiang Saen, and downstream has diverted the river into a broad S-shaped loop in the otherwise straight course of the river. A 1.7-Ma basalt within the bedrock channel 45-km downstream of Chiang Saen indicates little vertical incision by the river. Satellite images show former channels in the Chiang Saen area, meander-point-bar scrolls (radii of curvature > 1.2 km), and floodplain edges as arcuate cuts of similar curvature

  7. Zero-inflated modeling of fish catch per unit area resulting from multiple gears: Application to channel catfish and shovelnose sturgeon in the Missouri River

    Science.gov (United States)

    Arab, A.; Wildhaber, M.L.; Wikle, C.K.; Gentry, C.N.

    2008-01-01

    Fisheries studies often employ multiple gears that result in large percentages of zero values. We considered a zero-inflated Poisson (ZIP) model with random effects to address these excessive zeros. By employing a Bayesian ZIP model that simultaneously incorporates data from multiple gears to analyze data from the Missouri River, we were able to compare gears and make more year, segment, and macrohabitat comparisons than did the original data analysis. For channel catfish Ictalurus punctatus, our results rank (highest to lowest) the mean catch per unit area (CPUA) for gears (beach seine, benthic trawl, electrofishing, and drifting trammel net); years (1998 and 1997); macrohabitats (tributary mouth, connected secondary channel, nonconnected secondary channel, and bend); and river segment zones (channelized, inter-reservoir, and least-altered). For shovelnose sturgeon Scaphirhynchus platorynchus, the mean CPUA was significantly higher for benthic trawls and drifting trammel nets; 1998 and 1997; tributary mouths, bends, and connected secondary channels; and some channelized or least-altered inter-reservoir segments. One important advantage of our approach is the ability to reliably infer patterns of relative abundance by means of multiple gears without using gear efficiencies. ?? Copyright by the American Fisheries Society 2008.

  8. Lithologic and hydrologic controls of mixed alluvial-bedrock channels in flood-prone fluvial systems: bankfull and macrochannels in the Llano River watershed, central Texas, USA

    Science.gov (United States)

    Heitmuller, Frank T.; Hudson, Paul F.; Asquith, William H.

    2015-01-01

    The rural and unregulated Llano River watershed located in central Texas, USA, has a highly variable flow regime and a wide range of instantaneous peak flows. Abrupt transitions in surface lithology exist along the main-stem channel course. Both of these characteristics afford an opportunity to examine hydrologic, lithologic, and sedimentary controls on downstream changes in channel morphology. Field surveys of channel topography and boundary composition are coupled with sediment analyses, hydraulic computations, flood-frequency analyses, and geographic information system mapping to discern controls on channel geometry (profile, pattern, and shape) and dimensions along the mixed alluvial-bedrock Llano River and key tributaries. Four categories of channel classification in a downstream direction include: (i) uppermost ephemeral reaches, (ii) straight or sinuous gravel-bed channels in Cretaceous carbonate sedimentary zones, (iii) straight or sinuous gravel-bed or bedrock channels in Paleozoic sedimentary zones, and (iv) straight, braided, or multithread mixed alluvial–bedrock channels with sandy beds in Precambrian igneous and metamorphic zones. Principal findings include: (i) a nearly linear channel profile attributed to resistant bedrock incision checkpoints; (ii) statistically significant correlations of both alluvial sinuosity and valley confinement to relatively high f (mean depth) hydraulic geometry values; (iii) relatively high b (width) hydraulic geometry values in partly confined settings with sinuous channels upstream from a prominent incision checkpoint; (iv) different functional flow categories including frequently occurring events (values (most ≤ 0.45) that develop at sites with unit stream power values in excess of 200 watts per square meter (W/m2); and (vi) downstream convergence of hydraulic geometry exponents for bankfull and macrochannels, explained by co-increases of flood magnitude and noncohesive sandy sediments that collectively minimize

  9. Trait-based surveillance of flood channel effects on the River Thames

    Directory of Open Access Journals (Sweden)

    Leslie Patrick Ruse

    2012-10-01

    Full Text Available An artificial anabranch was opened to the main River Thames by the end of 2001. Chironomid pupal exuviae have been sampled from sites along the main river since 1977 including sites above and below the anabranch. Two sites on the anabranch have also been surveyed since its opening. Long-term surveillance of the chironomid assemblage prior to construction of the anabranch provided a reference state by which its impact could be assessed. Feeding and habitat preferences were attributed to chironomid taxa while additional environmental -tolerance traits were derived from the long-term data of the Thames. Canonical Correspondence Analysis, with spatial variation partialled out, was used to select temporal environmental variables explaining chironomid taxa distribution. Taxa with significant t-values in the regression with selected environmental variables were then included in the subsequent analysis of variance of traits by General Linear Modelling. From 1977 up to 2001 lower Thames sites, above and below the anabranch, showed no significant changes in any of the traits investigated. Four surveys from 2002 to 2009 have revealed some significant changes downstream of the anabranch, both in comparison with before-construction and between sites. These changes suggest the anabranch is providing a sink for poor-quality sediments. Immediately downstream of the anabranch fine sediment-dwelling chironomids have declined within the Thames, chironomids sensitive to ammonia have increased while chironomids tolerant of organic pollution have decreased.doi: 10.5324/fn.v31i0.1360.Published online: 17 October 2012.

  10. Evolutionary trajectory of channel planforms in the middle Garonne River (Toulouse, SW France) over a 130-year period: Contribution of mixed multiple factor analysis (MFAmix)

    Science.gov (United States)

    David, Mélodie; Labenne, Amaury; Carozza, Jean-Michel; Valette, Philippe

    2016-04-01

    The purpose of this study is to propose a methodological essay for defining evolutionary trajectories of channel planforms and to examine the channel change in the middle Garonne River (southwest France) over a 130-year period. The study focuses on a reach of ~ 90 km situated downstream from the city of Toulouse. A set of four historical maps (1868, 1940s, 1970s, and 2000s) is used to build a geomorphometric diachronic database. Data processing through mixed multiple factor analysis (MFAmix) and hierarchical cluster analysis (HCA) allows distinction between four homogeneous zones within the study reach, depending on their evolutionary trajectories. Channel behavior in the upstream and median zones evolved as of the beginning of the study period (narrowing of the fluvial area, colonization by vegetation, and removal of alluvial bars), likely owing to punctual anthropogenic actions. The downstream zone is characterized by stabilization of the channel and alluvial bar removal over the second half of the twentieth century, coinciding with the campaign undertaken by French local authorities between 1960 and 1984 to protect river banks. The role of climate transition between the Little Ice Age (LIA) and the onset of the Global Warming period (GW) is also discussed. Results generally are consistent with the chronology established for most European rivers.

  11. Optimizing Spanwise & Streamwise Spacings of MHK Devices in a Trapezoidal River Channel

    Science.gov (United States)

    Roberts, J. D.; Barco, J.; Johnson, E.; James, S. C.; Jones, C. A.; Jepsen, R. A.

    2011-12-01

    The world is facing significant challenges meeting the energy demands for the future. Growing populations and developing economies as well as increasing energy expenditures highlight the need for a spectrum of energy sources. One promising renewable is marine and hydrokinetic (MHK) energy, which has the potential to make important contributions to future energy portfolios. Increasing interest in MHK energy has spurred to significant research on optimal placement of emerging technologies to maximize energy capture and minimize potential negative effects on the environment. Understanding changes to near- and far-field hydrodynamics is necessary to assess optimal placement. This work demonstrates a newly developed modeling tool that can be used to optimize MHK array layouts to maximize energy capture while minimizing potentially harmful environmental effects. SNL has developed and implemented modifications to an existing flow, sediment-dynamics, and water-quality code (SNL-EFDC) to qualify, quantify, and visualize the interaction and influence of MHK-device operation at a representative site using an appropriate and verified representation of momentum/energy extraction and turbulent wake generation. Various hypothetical MHK array configurations are simulated within a straight rectangular unidirectional flow conditions channel at several water column depths. Results show that the turbine-array power efficiency increased, nonlinearly, as turbine spacing was increased in both the spanwise and streamwise directions as well as when turbines were placed higher in the water column. Contour plots facilitate evaluation of tradeoffs between efficiency and spacing. In addition, results show that flow increases around and over/under the array leading to elevated velocities in the main channel, near the bank, and near the sediment bed, which may have potential implications for bank and bottom erosion, and navigation. SNL-EFDC's "MHK friendly" array-optimization tool is and will

  12. SPECIES COMPOSITION, HORIZONTAL DISTRIBUTION AND SEASONAL SUCCESSION OF PHYTOPLANKTON IN THE CHANNEL FROM DONGTING LAKE TO THE CHANGJIANG RIVER, CHINA

    Institute of Scientific and Technical Information of China (English)

    魏印心

    2002-01-01

    The species composition, horizontal distribution and seasonal succession of the phytoplankton at five sampling stations in the channel between Dongting Lake and the Changjiang River, China were studied from May 1995 to December 1997. A total of 416 taxa were observed; diatoms comprised the most diversetaxonomic group representing 58.2 % of the total species. The β-mesotrophic indicators were 92 taxa or 22 % of the total, the α-mesotrophic or α,β-eutrophic indicators decreased distinctly to 20 taxa or 4.8 % of the total. The species number and composition of various phyla were approximately similar at Stations 1, 2, 3 and 4, but at Station 5 the number of species was the minimum and the ratio of diatoms to total phytoplankton in the number of species was the highest. In seasonal succession of the phytoplankton species, the number was the highest in May and June, lower in December, January, March and July in the channel. The dominant species were different in different months. The ratio of diatoms speciesnumber to blue green algae and green algae species number diminished gradually from winter to summer and autumn, and then increased gradually from autumn to winter and early spring in the annual cycle. Margalef, Simpson and Shannon-Weaver diversity indices changed in different months, their values were higher in winter, lower in summer. Nygaard's diatoms quotients were lower in winter, then in spring and autumn, higher in summer. These results indicated that the water quality was the best in winter, better in spring and autumn than in summer. The relationship between the structure of the phytoplankton community and the water environmental quality was discussed.``

  13. Preliminary assessment of channel stability and bed-material transport in the Tillamook Bay tributaries and Nehalem River basin, northwestern Oregon

    Science.gov (United States)

    Jones, Krista L.; Keith, Mackenzie K.; O'Connor, Jim E.; Mangano, Joseph F.; Wallick, J. Rose

    2012-01-01

    This report summarizes a preliminary study of bed-material transport, vertical and lateral channel changes, and existing datasets for the Tillamook (drainage area 156 square kilometers [km2]), Trask (451 km2), Wilson (500 km2), Kilchis (169 km2), Miami (94 km2), and Nehalem (2,207 km2) Rivers along the northwestern Oregon coast. This study, conducted in coopera-tion with the U.S. Army Corps of Engineers and Oregon Department of State Lands to inform permitting decisions regarding instream gravel mining, revealed that: * Study areas along the six rivers can be divided into reaches based on tidal influence and topography. The fluvial (nontidal or dominated by riverine processes) reaches vary in length (2.4-9.3 kilometer [km]), gradient (0.0011-0.0075 meter of elevation change per meter of channel length [m/m]), and bed-material composition (a mixture of alluvium and intermittent bedrock outcrops to predominately alluvium). In fluvial reaches, unit bar area (square meter of bar area per meter of channel length [m2/m]) as mapped from 2009 photographs ranged from 7.1 m2/m on the Tillamook River to 27.9 m2/m on the Miami River. * In tidal reaches, all six rivers flow over alluvial deposits, but have varying gradients (0.0001-0.0013 m/m) and lengths affected by tide (1.3-24.6 km). The Miami River has the steepest and shortest tidal reach and the Nehalem River has the flattest and longest tidal reach. Bars in the tidal reaches are generally composed of sand and mud. Unit bar area was greatest in the Tidal Nehalem Reach, where extensive mud flats flank the lower channel. * Background factors such as valley and channel confinement, basin geology, channel slope, and tidal extent control the spatial variation in the accumulation and texture of bed material. Presently, the Upper Fluvial Wilson and Miami Reaches and Fluvial Nehalem Reach have the greatest abundance of gravel bars, likely owing to local bed-material sources in combination with decreasing channel gradient and

  14. Two-dimensional appraisal of geomorphic control on braidplain and in-channel structural connectivity of a braided-wandering river from aerial photos (case study the Belá River, Slovakia)

    Science.gov (United States)

    Kidová, Anna; Lehotský, Milan

    2014-05-01

    Throughout the Europe, reductions in the extent of braided river reaches have occurred since the end of the 19th century and throughout the 20th century. This is a particular study priority of present braided rivers, because they are unique natural entities and rich ecosystems. Understanding the temporal and spatial connectivity that has characterised braidplain and channel behaviour will give crucial information about the evolution and management decisions of this type of rivers. The aim of the contribution is to understand how the spatial connectivity has developed on the Belá River (23.6 km, average annual discharge 6.8 m3 s-1 at mouth, Strahler ord. 5, as a laterally unconfined, gravel-bed river with braided-wandering pattern situated in the North of Slovakia); evaluate how time-spatial linkages of channel and floodplain landforms have been affected by recent large flood events and local factors. Four geomorphological coupling levels of the structural connectivity for seven time periods, using aerial photography (1949-2009) have been investigated: i. valley slope/low terraces-braidplain; ii. channel-channel level; iii. channel-bank level; iiii. bar-channel bed level. Each time horizon has been selected to be representative for estimation linkages changes after large flood event. The development of geomorphological structural connectivity is examined by documenting sequential changes in braidplain width, channel planform (braided and wandering indices), bar and bank attached erosion/accretion areas as parameters reflecting four types of connectivity. The changes in the structural connectivity is expressed in the three-point ordinal scale (1. increasing; 2. unchanging; 3. decreasing) as well as in the map expression of river reaches zonation. Generally, the width of braidplain with decreasing trend refers to long term decoupling valley slope/terraces-braidplain linkages. This trend is prove also by decreasing of the braidplain area. The values of braided indices

  15. Heterogeneity of soil carbon pools and fluxes in a channelized and a restored floodplain section (Thur River, Switzerland

    Directory of Open Access Journals (Sweden)

    E. Samaritani

    2011-06-01

    Full Text Available Due to their spatial complexity and dynamic nature, floodplains provide a wide range of ecosystem functions. However, because of flow regulation, many riverine floodplains have lost their characteristic heterogeneity. Restoration of floodplain habitats and the rehabilitation of key ecosystem functions, many of them linked to organic carbon (C dynamics in riparian soils, has therefore become a major goal of environmental policy. The fundamental understanding of the factors that drive the processes involved in C cycling in heterogeneous and dynamic systems such as floodplains is however only fragmentary.

    We quantified soil organic C pools (microbial C and water extractable organic C and fluxes (soil respiration and net methane production in functional process zones of adjacent channelized and widened sections of the Thur River, NE Switzerland, on a seasonal basis. The objective was to assess how spatial heterogeneity and temporal variability of these pools and fluxes relate to physicochemical soil properties on one hand, and to soil environmental conditions and flood disturbance on the other hand.

    Overall, factors related to seasonality and flooding (temperature, water content, organic matter input affected soil C dynamics more than soil properties did. Coarse-textured soils on gravel bars in the restored section were characterized by low base-levels of organic C pools due to low TOC contents. However, frequent disturbance by flood pulses led to high heterogeneity with temporarily and locally increased C pools and soil respiration. By contrast, in stable riparian forests, the finer texture of the soils and corresponding higher TOC contents and water retention capacity led to high base-levels of C pools. Spatial heterogeneity was low, but major floods and seasonal differences in temperature had additional impacts on both pools and fluxes. Soil properties and base levels of C pools in the dam foreland of the channelized section

  16. Heterogeneity of soil carbon pools and fluxes in a channelized and a restored floodplain section (Thur River, Switzerland

    Directory of Open Access Journals (Sweden)

    E. Samaritani

    2011-01-01

    Full Text Available Due to their spatial complexity and dynamic nature, floodplains provide a wide range of ecosystem functions. However, because of flow regulation, many riverine floodplains have lost their characteristic heterogeneity. Restoration of floodplain habitats and the rehabilitation of key ecosystem functions has therefore become a major goal of environmental policy. Many important ecosystem functions are linked to organic carbon (C dynamics in riparian soils. The fundamental understanding of the factors that drive the processes involved in C cycling in heterogeneous and dynamic systems such as floodplains is however only fragmentary.

    We quantified soil organic C pools (microbial C and water extractable organic C and fluxes (soil respiration and net methane production in functional process zones of adjacent channelized and widened sections of the Thur River, NE Switzerland, on a seasonal basis. The objective was to assess how spatial heterogeneity and temporal variability of these pools and fluxes relate to physicochemical soil properties on one hand, and to soil environmental conditions and flood disturbance on the other hand.

    Overall, factors related to seasonality and flooding (temperature, water content, organic matter input affected soil C dynamics more than soil properties did. Coarse-textured soils on gravel bars in the restored section were characterized by low base-levels of organic C pools due to low TOC contents. However, frequent disturbance by flood pulses led to high heterogeneity with temporarily and locally increased pools and soil respiration. By contrast, in stable riparian forests, the finer texture of the soils and corresponding higher TOC contents and water retention capacity led to high base-levels of C pools. Spatial heterogeneity was low, but major floods and seasonal differences in temperature had additional impacts on both pools and fluxes. Soil properties and base levels of C pools in the dam foreland of the

  17. Comparative effects of oil palm and selective logging on erosion, river channels and water chemistry in Malaysian steeplands

    Science.gov (United States)

    Walsh, Rory; Nainar, Anand; Nurhidayu, Siti; Higton, Sam; Annammala, Kogilavani; Wall, Katy; Bidin, Kawi; Blake, William; Darling, Isabella

    2017-04-01

    Oil palm land-use has expanded greatly in recent decades in SE Asia and other parts of the wet tropics, including to steepland areas, where bench-terraced landscaping is involved. Retaining (and sometimes restoring) riparian forest strips and rainforest fragments on the steepest slopes have been adopted as elements of strategies designed to reduce adverse effects on runoff generation, erosion, downstream sedimentation, flooding and pollutional problems - as well as biodiversity and emissions. Results of catchment monitoring, soil erosion and sediment fingerprinting research in oil palm and selectively logged steeplands of eastern Sabah and Peninsular Malaysia are presented. The evidence indicates the greater scale and temporal persistence of effects that oil palm land-use (compared with selective logging) has had on suspended sediment dynamics, soil erosion, downstream sedimentation, channel geometry and dynamics and river pollution. The importance of (1) high densities of roads and tracks and (2) relatively impermeable bench-terraced terrain in enhancing runoff, sediment and nutrient outputs in storm events is stressed. Influences of oil palm management practices including riparian forest strips in increasing or reducing these effects are critically reviewed and ways of increasing the effectiveness of riparian forest strips are proposed. The design and rationale of current projects exploring and testing consequences of existing and proposed improved land management practices are briefly described. The key importance of involvement of people from the oil palm industry (including multinational companies, smallholders and their organizations) and Government bodies that are responsible for land-use policies and land management practices is stressed.

  18. Methow River Studies, Washington: abundance estimates from Beaver Creek and the Chewuch River screw trap, methodology testing in the Whitefish Island side channel, and survival and detection estimates from hatchery fish releases, 2013

    Science.gov (United States)

    Martens, Kyle D.; Fish, Teresa M.; Watson, Grace A.; Connolly, Patrick J.

    2014-01-01

    2008, focuses on the evaluation of the M2 reach (rkm 66– 80) of the mainstem Methow River prior to restoration actions planned by Reclamation and Yakama Nation. The M2 study was designed to help understand the inter-relationships between stream habitat and the life history of various fish species to explain potential success or limitations in response to restoration actions. To help document changes derived by restoration, two reference reaches (Upper Methow between rkm 85 and 90, and Chewuch River between rkm 4 and 11) were identified based on relative lack of disturbance, proximity to the restoration reach, and relative unconfined geomorphology. A control reach (Lower Methow between rkm 57 and 64, also referred to as “Silver Reach”) was 2 identified based on its similar disturbance as the reference reach, proximity to the restoration reach, and relatively unconfined geomorphology. Products to date include Barber and others (2011), Bellmore (2011), Tibbits and others (2012), Bellmore and others (2013), Benjamin and others (2013), Romine and others (2013b), Bellmore and other (2014), Martens and others (2014), and Martens and Connolly (2014). The third phase of work has been to help with the development and to provide data for modeling efforts. Most of the planned M2 reach restoration is focused on the creation or improvement of offchannel habitat, especially side channels. The pre-restoration portion of this study has been documented by Martens and Connolly (2014). Side channel restoration actions were initiated in 2012 (Whitefish Island side channel, also referred to as SC3; rkm 76) and are planned to continue over the next several years. The Whitefish Island side channel was modified to maintain hydrological connection with the mainstem throughout the year. In addition, several log structures were installed and pools were deepened to create fish habitat. Prior to restoration, this side channel would lose hydrological connection with the mainstem Methow River

  19. The signature of bankfull hydraulic conditions reflected by properties of the channel bank: a case study from the Selenga River delta, Lake Baikal, Russia

    Science.gov (United States)

    Dong, T. Y.; Nittrouer, J. A.; Czapiga, M. J.; Ma, H.; McElroy, B. J.; Il'icheva, E.; Pavlov, M.; Parker, G.

    2016-12-01

    A recent model developed to describe variable river channel Shields number proposed that the bankfull shear velocity value is nearly independent of bed material grain size, and instead is dependent on the kinematic viscosity of water. This fluid property has an important influence on the settling velocity of washload sediment, which is material generally not found on the channel bed, but is deposited on the adjacent levees during overbank flow. It is therefore hypothesized that bankfull shear velocity values for a lowland fluvial channel can be estimated based on the grain size properties of the bank sediment, after considering the vegetated state of the bank. This hypothesis is tested using a variety of data collected during two field expeditions (2014, 2016) to the Selenga River Delta, Lake Baikal, Russia, because this system demonstrates significant changes in bank material and flow hydraulic conditions across the distributary channel network. The data include: 1) channel geometry measurements, 2) bank and floodplain sediment samples, 3) water samples to measure washload concentration and grain size, 4) flow velocity measurements, and 5) bank vegetation type, to estimate sediment trapping efficiency. Analyses of the data document a downstream fining of bank sediment grain size, with medium sand present near the delta apex, to mud at the delta margin. Bankfull channel depth decreases downstream, from meter-scale near the apex, to decimeter-scale at the delta margin, where the channel banks transition from subaerial to subaqueous expression. Flow velocity - decreasing downstream - is used to calculate shear velocity. An analytical framework is developed to explore the physical connections between grain size of the bank material, bankfull depth, and shear velocity. This analysis is the first to establish a connection between bankfull geometry, bank material properties, and Shields number, and therefore provides insights regarding fluvial-deltaic morphodynamics.

  20. Coupling channel evolution monitoring and RFID tracking in a large, wandering, gravel-bed river: Insights into sediment routing on geomorphic continuity through a riffle-pool sequence

    Science.gov (United States)

    Chapuis, Margot; Dufour, Simon; Provansal, Mireille; Couvert, Bernard; de Linares, Matthieu

    2015-02-01

    Bedload transport and bedform mobility in large gravel-bed rivers are not easily monitored, especially during floods. Large reaches present difficulties in bed access during flows for flow measurements. Because of these logistical issues, the current knowledge about bedload transport processes and bedform mobility lacks field-based information, while this missing information would precisely match river management needs. The lack of information linking channel evolution and particle displacements is even more striking in wandering reaches. The Durance River is a large, wandering, gravel-bed river (catchment area: 14,280 km2; mean width: 240 m), located in the southern French Alps and highly impacted by flow diversion and gravel mining. In order to improve current understanding of the link between sediment transport processes and river bed morphodynamics, we set up a sediment particle survey in the channel using Radio Frequency Identification (RFID) tracking and topographic surveys (GPS RTK and scour chains) for a 4-year recurrence interval flood. By combining topographic changes before and after a flood, intraflood erosion/deposition patterns from scour chains, differential routing of tracer particles, and spatial distribution of bed shear stress through a complex reach, this paper aims to define the critical shear stress for significant sediment mobility in this setting. Gravel tracking highlights displacement patterns in agreement with bar downstream migration and transport of particles across the riffle within this single flood event. Because no velocity measurements were possible during flood, a TELEMAC three-dimensional model helped interpret particle displacements by estimating spatial distribution of shear stresses and flow directions at peak flow. Although RFID tracking in a large, wandering, gravel-bed river does have some technical limitations (burial, recovery process time-consuming), it provides useful information on sediment routing through a riffle

  1. Hack's relation and optimal channel networks: The elongation of river basins as a consequence of energy minimization

    Science.gov (United States)

    Ijjasz-Vasquez, Ede J.; Bras, Rafael L.; Rodriguez-Iturbe, Ignacio

    1993-08-01

    As pointed by Hack (1957), river basins tend to become longer and narrower as their size increases. This work shows that this property may be partially regarded as the consequence of competition and minimization of energy expenditure in river basins.

  2. Today's sediment budget of the Rhine River channel, focusing on the Upper Rhine Graben and Rhenish Massif

    NARCIS (Netherlands)

    Frings, Roy M.; Gehres, Nicole; Promny, Markus; Middelkoop, Hans|info:eu-repo/dai/nl/152500693; Schüttrumpf, Holger; Vollmer, Stefan

    2014-01-01

    The river bed of the Rhine River is subject to severe erosion and sedimentation. Such high geomorphological process rates are unwanted for economical, ecological, and safety reasons. The objectives of this study were (1) to quantify the geomorphological development of the Rhine River between 1985

  3. Methow River Studies, Washington: abundance estimates from Beaver Creek and the Chewuch River screw trap, methodology testing in the Whitefish Island side channel, and survival and detection estimates from hatchery fish releases, 2013

    Science.gov (United States)

    Martens, Kyle D.; Fish, Teresa M.; Watson, Grace A.; Connolly, Patrick J.

    2014-01-01

    2008, focuses on the evaluation of the M2 reach (rkm 66– 80) of the mainstem Methow River prior to restoration actions planned by Reclamation and Yakama Nation. The M2 study was designed to help understand the inter-relationships between stream habitat and the life history of various fish species to explain potential success or limitations in response to restoration actions. To help document changes derived by restoration, two reference reaches (Upper Methow between rkm 85 and 90, and Chewuch River between rkm 4 and 11) were identified based on relative lack of disturbance, proximity to the restoration reach, and relative unconfined geomorphology. A control reach (Lower Methow between rkm 57 and 64, also referred to as “Silver Reach”) was 2 identified based on its similar disturbance as the reference reach, proximity to the restoration reach, and relatively unconfined geomorphology. Products to date include Barber and others (2011), Bellmore (2011), Tibbits and others (2012), Bellmore and others (2013), Benjamin and others (2013), Romine and others (2013b), Bellmore and other (2014), Martens and others (2014), and Martens and Connolly (2014). The third phase of work has been to help with the development and to provide data for modeling efforts. Most of the planned M2 reach restoration is focused on the creation or improvement of offchannel habitat, especially side channels. The pre-restoration portion of this study has been documented by Martens and Connolly (2014). Side channel restoration actions were initiated in 2012 (Whitefish Island side channel, also referred to as SC3; rkm 76) and are planned to continue over the next several years. The Whitefish Island side channel was modified to maintain hydrological connection with the mainstem throughout the year. In addition, several log structures were installed and pools were deepened to create fish habitat. Prior to restoration, this side channel would lose hydrological connection with the mainstem Methow River

  4. CHNTRN: a CHaNnel TRaNsport model for simulating sediment and chemical distribution in a stream/river network

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.

    1983-09-01

    This report presents the development of a CHaNnel TRaNsport model for simulating sediment and chemical distribution in a stream/river network. A particular feature of the model is its capability to deal with the network system that may consist of any number of joined and branched streams/rivers of comparable size. The model employs a numerical method - an integrated compartment method (ICM) - which greatly facilitates the setup of the matrix equation for the discrete field approximating the corresponding continuous field. Most of the possible boundary conditions that may be anticipated in real-world problems are considered. These include junctions, prescribed concentration, prescribed dispersive flux, and prescribed total flux. The model is applied to two case studies: (1) a single river and (2) a five-segment river in a watershed. Results indicate that the model can realistically simulate the behavior of the sediment and chemical variations in a stream/river network. 11 references, 10 figures, 3 tables.

  5. Export of materials along a tidal river channel that links a coastal lagoon to the adjacent sea

    Directory of Open Access Journals (Sweden)

    Javier Aldeco Ramírez

    2012-09-01

    Full Text Available Intratidal variability and flux of salt, chlorophyll-a and suspended materials were evaluated in a shallow tropical tidal channel linking a coastal lagoon to the western Gulf of Mexico. Velocity, temperature and conductivity were used to calculate the fluxes. Data were recorded during three tidal velocity cycles (tvc under extreme river discharge conditions. Chlorophyll-a and suspended materials were determined below the surface. In both seasons (dry and rainy, the flow was ebb-dominated and with longer duration than when in flood. Maximum current velocities were 0.30 m s-1 in May (dry season and 0.60 m s-1 in September (rainy season. In the dry season the mean chlorophyll-a export was of 7.56 Kg over tvc while the import was of 3.32 Kg. In the rainy season mean export (47.3 Kg was 6 times greater than the import (7.93 Kg over tvc. Phytoplankton was dominated by organisms of marine origin. The mean of exported, suspended materials in the rainy season (111.3 Kg was 4.6 times greater (859 Kg than that in the dry season (184.7 Kg over tvc. Tidal velocity asymmetry is an effective mechanism of exportation, introducing relatively warm and saltier water into the river through the tidal channel.A variabilidade intramaré, o fluxo de salinidade, a clorofila-a e material em suspensão foram avaliados em um canal superficial de maré tropical em uma lagoa costeira ao oeste do Golfo do México. Os dados de velocidade, temperatura e condutividade foram usados para cálculo dos fluxos durante três ciclos de velocidades das marés (tvc sob condições extremas de descarga. A Clorofila-a e material em suspensão foram determinados abaixo em subsuperfície. Em ambas as estações (seca e chuvosa, o fluxo dominante foi durante o refluxo e com duração maior durante o fluxo de entrada. A máxima velocidade encontrada foi 0.30 m s-1 em maio (estação seca e 0.60 m s-1 em setembro (estação chuvosa. Durante a época seca foram exportadas 7.56 Kg de clorofila

  6. Three new species of the armored catfish genus Loricaria (Siluriformes: Loricariidae from river channels of the Amazon basin

    Directory of Open Access Journals (Sweden)

    Matthew R. Thomas

    2008-01-01

    Full Text Available Three new species of Loricaria are described from large white- and black-water river channels of the Amazon basin of Brazil, the upper rio Negro drainage of southern Venezuela, and clear waters of the lower rio Tocantins. Loricaria spinulifera and L. pumila differ from other species of Loricaria by having unique patterns of abdominal plate development and hypertrophied odontodes forming conspicuous crests on dorsal surfaces of the head and predorsal plates. Both are small species of Loricaria, reaching sexual maturity at less than 120 mm SL, and exhibiting sexually dimorphic characters consistent with members of the L. cataphracta complex. Loricaria spinulifera differs from L. pumila in having a unique arrangement of buccal papillae and large thorn-like odontodes on the dorsum of the head. Loricaria pumila is the smallest known Loricaria, reaching sexual maturity at less than 80 mm SL. Loricaria lundbergi differs from other Loricaria by having a unique abdominal plate pattern, broad head, and small basicaudal plate. Loricaria lundbergi is sympatric with L. spinulifera in the lower rio Negro drainage, but is also known from the rio Baria system of the Casiquiare drainage. Loricaria pumila occurs in the lower rio Amazonas and lower rio Tocantins. All three new species exhibit varying degrees of reduction in eye size and pigmentation seen in other fishes inhabiting deep river channels of South America.Três novas espécies de Loricaria são descritas provenientes dos canais de grandes rios de águas brancas e pretas da bacia Amazônica brasileira, da bacia do alto rio Negro no sul da Venezuela e das águas claras do baixo rio Tocantins. Loricaria lundbergi é simpátrica com L. spinulifera no baixo rio Negro, mas também é conhecida para o sistema do rio Baria, drenagem do Cassiquiare. Loricaria pumila ocorre no baixo rio Amazonas e baixo rio Tocantins. Loricaria spinulifera e L. pumila diferem de outras Loricaria por apresentarem odont

  7. Two-dimensional hydrodynamic modeling to quantify effects of peak-flow management on channel morphology and salmon-spawning habitat in the Cedar River, Washington

    Science.gov (United States)

    Czuba, Christiana; Czuba, Jonathan A.; Gendaszek, Andrew S.; Magirl, Christopher S.

    2010-01-01

    The Cedar River in Washington State originates on the western slope of the Cascade Range and provides the City of Seattle with most of its drinking water, while also supporting a productive salmon habitat. Water-resource managers require detailed information on how best to manage high-flow releases from Chester Morse Lake, a large reservoir on the Cedar River, during periods of heavy precipitation to minimize flooding, while mitigating negative effects on fish populations. Instream flow-management practices include provisions for adaptive management to promote and maintain healthy aquatic habitat in the river system. The current study is designed to understand the linkages between peak flow characteristics, geomorphic processes, riverine habitat, and biological responses. Specifically, two-dimensional hydrodynamic modeling is used to simulate and quantify the effects of the peak-flow magnitude, duration, and frequency on the channel morphology and salmon-spawning habitat. Two study reaches, representative of the typical geomorphic and ecologic characteristics of the Cedar River, were selected for the modeling. Detailed bathymetric data, collected with a real-time kinematic global positioning system and an acoustic Doppler current profiler, were combined with a LiDAR-derived digital elevation model in the overbank area to develop a computational mesh. The model is used to simulate water velocity, benthic shear stress, flood inundation, and morphologic changes in the gravel-bedded river under the current and alternative flood-release strategies. Simulations of morphologic change and salmon-redd scour by floods of differing magnitude and duration enable water-resource managers to incorporate model simulation results into adaptive management of peak flows in the Cedar River. PDF version of a presentation on hydrodynamic modelling in the Cedar River in Washington state. Presented at the American Geophysical Union Fall Meeting 2010.

  8. The effect of wet-dry weathering on the rate of bedrock river channel erosion by saltating gravel

    Science.gov (United States)

    Inoue, Takuya; Yamaguchi, Satomi; Nelson, Jonathan M.

    2017-05-01

    Previous work has shown that the bedrock erosion rate E because of collisions of saltating bedload can be expressed by E = βqb(1-Pc), where qb is the sediment transport rate, Pc is the extent of alluvial cover, and β is the abrasion coefficient. However, the dependence of the abrasion coefficient on the physical characteristics of the bedrock material is poorly known, and in particular, the effects of wet-dry weathering on the saltation-abrasion bedrock incision has not been specifically characterized. Observation suggests that the typical wet-dry cycling of exposed bedrock in river beds gives rise to cracks and voids that are likely to alter the incision rate of the material when subjected to impacts of moving sediment. In this study, flume experiments are performed to develop an understanding of how wet-dry cycling affects the rock tensile strength and the bedrock erosion rate. To represent the physical effects of weathering, boring cores taken from natural bedrock channel are exposed to artificial wet-dry cycles. The experimental results suggest the following: (1) the abrasion coefficient for fresh bedrock is estimated by β = 1.0 × 10- 4σT- 2(d/ksb)0.5, where σT is the tensile strength, d is the diameter of colliding gravel, and ksb is the hydraulic roughness height of bedrock; (2) the tensile strength of the bedrock decreases exponentially as a result of repeated wet-dry cycles, σT/σT0 = exp (-CTNWa0/σT0), where σT0 is the initial tensile strength, Wa0 is the initial normalized rate of water absorption., N is the number of wet-dry cycles, and CT is a constant; (3) the erosion rate of fresh bedrock depends on the inverse of the square of tensile strength, but the erosion rate of weathered bedrock depends on the - 1.5 power of tensile strength.

  9. Near-Channel Sediment Sources Now Dominate in Many Agricultural Landscapes: The Emergence of River-Network Models to Guide Watershed Management

    Science.gov (United States)

    Czuba, J. A.; Foufoula-Georgiou, E.; Gran, K. B.; Belmont, P.; Wilcock, P. R.

    2015-12-01

    Detailed sediment budgets for many agricultural watersheds are revealing a surprising story - that sediment is no longer primarily sourced from upland fields, but instead from near-channel sources. This is the case for the Minnesota River Basin (MRB) where an intensification and expansion of agricultural drainage combined with increased precipitation has (1) reduced surface runoff and erosion, (2) amplified streamflows, and (3) accelerated both near-channel sediment generation and sediment transport. Bluffs and streambanks in the MRB are now the dominant sources of sediment, but these features are not easily incorporated into traditional watershed-scale, sediment-transport models. Instead, we are advancing a network-based modeling framework that explicitly considers sediment sources, transport, and storage along a river network. We apply this framework to bed-material sediment transport in the Greater Blue Earth River Basin, the major sediment-generating subbasin of the MRB, where a recent sediment budget has quantified the locations and rates of erosion and deposition of major sediment sources and sinks (i.e., bluffs, streambanks/floodplains, agricultural fields, and ravines) over millennial and decadal timescales. With the river network as the basis of a simple model, inputs of sediment to the network are informed by the sediment budget and these inputs are tracked through the network using process-based time delays that incorporate uniform-flow hydraulics and at-capacity sediment transport. We explore how this sediment might move through the network and affect the variability of bed elevations under cases where the mechanisms of in-channel and floodplain storage are turned on and off. We will discuss timescales of movement of sediment through the system to better inform legacy effects and hysteresis, and also discuss targeted management actions that will most effectively reduce the detrimental effects of excess sediment.

  10. Assessment of transfer patterns and origins of in-channel wood in large rivers using repeated field surveys and wood characterisation (the Isère River upstream of Pontcharra, France)

    Science.gov (United States)

    Piégay, Hervé; Moulin, Bertrand; Hupp, Cliff R.

    2017-02-01

    When and whence does wood enter large mountain alluvial rivers? How stable through time are characteristics and quantities of wood deposited in a reach? These simple questions related to the complex practice of wood budgeting are explored on the Isère River in France. We hypothesise that (i) the wood originates from the riparian zone all along the alluvial reach and that (ii) the characters and quantity of wood in the reach can vary through time according to flood occurrence and provenance. In order to validate these hypotheses, two complementary approaches were performed: (i) wood pieces were surveyed along 190 km river length and taxonomy, in-channel wood macromorphology, and dendrochemistry were used to infer wood origin (local vs. upstream, respective subbasin contributions) and transport conditions; (ii) wood movement was monitored using both tracking techniques in specific sampling plots and with an experiment orchestrated using wood placement coupled with a significant artificial flood. Surveys were done over a period of 3 years so as to include two distinct sampling events to explore wood deposition and mobilisation within a channel network under different flood conditions. One of the subbasins, the Arly River, underwent a 1-in-30-year flood in 2004, allowing us to assess its effect on in-channel wood quantity and characteristics. Results confirm that wood is primarily introduced by erosion from river banks but they are not always as close as expected from the sites of deposition. Temporal variability of wood introduced, deposited, and transferred downstream is also significant in terms of abundance and origin as shown by dendrochemical and macromorphological signatures. The types of wood observed along the channel length changes through time. Large flood signature can be detected from wood characteristics and uplands make a slight contribution. But in average, wood characteristics do not change much (no significant difference between years and tributaries

  11. Maintenance Dredging of Charleston Harbor, Ashley River, and U.S. Navy Channels in Cooper River Charleston and Berkeley Counties, South Carolina.

    Science.gov (United States)

    1976-03-01

    commonly found in and around the marsh at various times of the year are blue crabs, hermit crabs, brown and white shrimp , mantis shrimp , grass shrimp ...increasing as a result of improved water quality. The Ashley River also serves as a nursery for blue crabs, brown and white shrimp , and various marine...few shrimp . 2.12.3.4.1 The river is classified in the SB category which purmits bathing, fishing, crabbing and other uses but prohibits the taking f

  12. Two-dimensional hydrodynamic modeling to quantify effects of peak-flow management on channel morphology and salmon-spawning habitat in the Cedar River, Washington

    Science.gov (United States)

    Barnas, C. R.; Czuba, J. A.; Gendaszek, A. S.; Magirl, C. S.

    2010-12-01

    The Cedar River in Washington State originates on the western slope of the Cascade Range and provides the City of Seattle with most of its drinking water, while also supporting a productive salmon habitat. Water-resource managers require detailed information on how best to manage high-flow releases from Chester Morse Lake, a large reservoir on the Cedar River, during periods of heavy precipitation to minimize flooding, while mitigating negative effects on fish populations. Instream flow-management practices include provisions for adaptive management to promote and maintain healthy aquatic habitat in the river system. The current study is designed to understand the linkages between peak flow characteristics, geomorphic processes, riverine habitat, and biological responses. Specifically, two-dimensional hydrodynamic modeling is used to simulate and quantify the effects of the peak-flow magnitude, duration, and frequency on the channel morphology and salmon-spawning habitat. Two study reaches, representative of the typical geomorphic and ecologic characteristics of the Cedar River, were selected for the modeling. Detailed bathymetric data, collected with a real-time kinematic global positioning system and an acoustic Doppler current profiler, were combined with a LiDAR-derived digital elevation model in the overbank area to develop a computational mesh. The model is used to simulate water velocity, benthic shear stress, flood inundation, and morphologic changes in the gravel-bedded river under the current and alternative flood-release strategies. Simulations of morphologic change and salmon-redd scour by floods of differing magnitude and duration enable water-resource managers to incorporate model simulation results into adaptive management of peak flows in the Cedar River.

  13. River channel monitoring of the Red River of the Texas and Oklahoma state boundary, U.S.A., using remote sensing techniques and the legal implications on riparian boundaries

    Science.gov (United States)

    Edwards, William David

    The study focuses on the Red River, partially forming the border of Arkansas, Oklahoma, and Texas in the United States of America. This river was chosen because of its volatility in migration and its impact on land value. The river can be relatively wide in areas, where the gradient is low, forming braided streams up to a mile wide. As land becomes more valuable, having a more readily and accurately defined boundary will become more important. Rivers serve as a natural boundary. Early in American cadastral systems, many descriptions used these natural features to make it easy to recognize by the public. Natural river boundaries migrate and change courses causing difficulties with land management. Riparian boundaries move with the changing channel of the river. Due to hydrogeological processes which contribute to accretion, erosion, reliction, and sometimes avulsion makes describing the sinuosity of riparian boundaries difficult. Riparian boundary descriptions usually are the product of a terrestrial land survey. The value of the land usually dictated the precision used by the land surveyor during the field data acquisition. Technological advances in the instrumentation used by the land surveyor have enabled both higher precision and accuracy in surveying data along with computers and software advancement to calculate the area of the land and more accurate management of the land. With the ability to provide specific analysis of land features through the development of geographic information system (GIS) software incorporating accurate terrain models, riparian boundaries can be easier to manage. Boundary definitions become more reliable with improved terrain information and numerical models. This research uses GIS software tools to delineate the gradient boundary along the river from elevation models derived from remote sensing instruments, also evaluate possible areas where potential avulsionary cut-off by the river using the same remote sensing data. If an area has

  14. Tidal-Fluvial and Estuarine Processes in the Lower Columbia River: I. Along-channel Water Level Variations, Pacific Ocean to Bonneville Dam

    Energy Technology Data Exchange (ETDEWEB)

    Jay, D. A.; Leffler, K.; Diefenderfer, Heida L.; Borde, Amy B.

    2015-03-01

    This two-part paper provides comprehensive time and frequency domain analyses and models of along-channel water level variations in the 234km-long Lower Columbia River and Estuary (LCRE) and documents the response of floodplain wetlands thereto. In Part I, power spectra, continuous wavelet transforms, and harmonic analyses are used to understand the influences of tides, river flow, upwelling and downwelling, and hydropower operations ("power-peaking") on the water level regime. Estuarine water levels are influenced primarily by astronomical tides and coastal processes, and secondarily by river flow. The importance of coastal and tidal influences decreases in the landward direction, and water levels are increasingly controlled by river flow variations at periods from ≤1 day to years. Water level records are only slightly non-stationary near the ocean, but become increasingly irregular upriver. Although astronomically forced tidal constituents decrease above the estuary, tidal fortnightly and overtide variations increase for 80-200km landward, both relative to major tidal constituents and in absolute terms.

  15. River

    Directory of Open Access Journals (Sweden)

    Morel Mathieu

    2016-01-01

    Full Text Available The OECD report “Boosting Resilience through Innovative Risk Governance” examines the efforts of OECD countries to prevent or reduce future disaster impacts, and highlights several key areas where improvements can be made. International collaboration is insufficiently utilised to address shocks that have increasingly global consequences. Institutional design plays a significant role in facilitating or hampering the engagement and investments of governmental and non-governmental stakeholders in disaster risk prevention and mitigation. To inform the design of “better” institutions, the OECD proposes the application of a diagnostic framework that helps governments identify institutional shortcomings and take actions to improve them. The goal of the case study on the Rhone River is to conduct an analysis of the progress, achievements and existing challenges in designing and implementing disaster risk reduction strategies through the Rhone Plan from a comparative perspective across a set of selected countries of this study, like Austria and Switzerland, will inform how to improve institutional frameworks governing risk prevention and mitigation. The case study will be used to identify examples of successful practice taking into account their specific country contexts, and analyse their potential for policy transfer.

  16. Two-Dimensional Hydrodynamic Modeling and Analysis of the Proposed Channel Modifications and Grade Control Structure on the Blue River near Byram's Ford Industrial Park, Kansas City, Missouri

    Science.gov (United States)

    Huizinga, Richard J.

    2007-01-01

    The Blue River Channel Modification project being implemented by the U.S. Army Corps of Engineers (USACE) is intended to provide flood protection within the Blue River valley in the Kansas City, Mo., metropolitan area. In the latest phase of the project, concerns have arisen about preserving the Civil War historic area of Byram's Ford and the associated Big Blue Battlefield while providing flood protection for the Byram's Ford Industrial Park. In 1996, the USACE used a physical model built at the Waterways Experiment Station (WES) in Vicksburg, Miss., to examine the feasibility of a proposed grade control structure (GCS) that would be placed downstream from the historic river crossing of Byram's Ford to provide a subtle transition of flow from the natural channel to the modified channel. The U.S. Geological Survey (USGS), in cooperation with the USACE, modified an existing two-dimensional finite element surface-water model of the river between 63d Street and Blue Parkway (the 'original model'), used the modified model to simulate the existing (as of 2006) unimproved channel and the proposed channel modifications and GCS, and analyzed the results from the simulations and those from the WES physical model. Modifications were made to the original model to create a model that represents existing (2006) conditions between the north end of Swope Park immediately upstream from 63d Street and the upstream limit of channel improvement on the Blue River (the 'model of existing conditions'). The model of existing conditions was calibrated to two measured floods. The model of existing conditions also was modified to create a model that represents conditions along the same reach of the Blue River with proposed channel modifications and the proposed GCS (the 'model of proposed conditions'). The models of existing conditions and proposed conditions were used to simulate the 30-, 50-, and 100-year recurrence floods. The discharge from the calibration flood of May 15, 1990, also

  17. The effect of wet-dry weathering on the rate of bedrock river channel erosion by saltating gravel

    Science.gov (United States)

    Inoue, Takuya; Yamaguchi, Satomi; Nelson, Jonathan M.

    2017-01-01

    Previous work has shown that the bedrock erosion rate E because of collisions of saltating bedload can be expressed by E = βqb(1-Pc), where qb is the sediment transport rate, Pc is the extent of alluvial cover, and β is the abrasion coefficient. However, the dependence of the abrasion coefficient on the physical characteristics of the bedrock material is poorly known, and in particular, the effects of wet-dry weathering on the saltation-abrasion bedrock incision has not been specifically characterized. Observation suggests that the typical wet-dry cycling of exposed bedrock in river beds gives rise to cracks and voids that are likely to alter the incision rate of the material when subjected to impacts of moving sediment. In this study, flume experiments are performed to develop an understanding of how wet-dry cycling affects the rock tensile strength and the bedrock erosion rate. To represent the physical effects of weathering, boring cores taken from natural bedrock channel are exposed to artificial wet-dry cycles. The experimental results suggest the following: (1) the abrasion coefficient for fresh bedrock is estimated by β = 1.0 × 10− 4σT− 2(d/ksb)0.5, where σT is the tensile strength, d is the diameter of colliding gravel, and ksb is the hydraulic roughness height of bedrock; (2) the tensile strength of the bedrock decreases exponentially as a result of repeated wet-dry cycles, σT/σT0 = exp (-CTNWa0/σT0), where σT0 is the initial tensile strength, Wa0 is the initial normalized rate of water absorption., N is the number of wet-dry cycles, and CT is a constant; (3) the erosion rate of fresh bedrock depends on the inverse of the square of tensile strength, but the erosion rate of weathered bedrock depends on the − 1.5 power of tensile strength.

  18. Research on River-crossing Channel Configuration of Medium-sized City%中等城市跨江通道布局研究

    Institute of Scientific and Technical Information of China (English)

    董凯

    2015-01-01

    根据过江通道总规模存在上限值和出行者对关键路段服务水平有一定要求的特点,基于离散网络设计理论,建立了中等城市跨江通道布局的双层规划模型,在粒子群算法中引入混沌理论和 Metropolis 接受准则,设计了新的求解算法。以常德市为研究案例,验证了模型和算法的有效性,为过江设施选址提供了理论依据。%According to the characteristics that the size of river-crossing channels has maximum value and travelers want to have a high level when they drive on bridges or tunnels,this paper established a bi-level programming model of river-crossing channel configuration in medium-sized city based on dis-crete network design theory,and created a new algorithm by introducing chaos theory and metropolis acceptance criterion into particle swarm optimization algorithm to find the optimum solution.Both the model and algorithm are validated by using the network of Changde as a case study,and the theoreti-cal basis is provided while searching for the optimal location of river-crossing channels.

  19. Lateral and vertical channel movement and potential for bed-material movement on the Madison River downstream from Earthquake Lake, Montana

    Science.gov (United States)

    Chase, Katherine J.; McCarthy, Peter M.

    2012-01-01

    The 1959 Hebgen Lake earthquake caused a massive landslide (Madison Slide) that dammed the Madison River and formed Earthquake Lake. The U.S. Army Corps of Engineers excavated a spillway through the Madison Slide to permit outflow from Earthquake Lake. In June 1970, high streamflows on the Madison River severely eroded the spillway channel and damaged the roadway embankment along U.S. Highway 287 downstream from the Madison Slide. Investigations undertaken following the 1970 flood events concluded that substantial erosion through and downstream from the spillway could be expected for streamflows greater than 3,500 cubic feet per second (ft3/s). Accordingly, the owners of Hebgen Dam, upstream from Earthquake Lake, have tried to manage releases from Hebgen Lake to prevent streamflows from exceeding 3,500 ft3/s measured at the U.S. Geological Survey (USGS) gaging station 0638800 Madison River at Kirby Ranch, near Cameron, Montana. Management of flow releases from Hebgen Lake to avoid exceeding the threshold streamflow at USGS gaging station 06038800 is difficult, and has been questioned for two reasons. First, no road damage was reported downstream from the Earthquake Lake outlet in 1993, 1996, and 1997 when streamflows exceeded the 3,500-ft3/s threshold. Second, the 3,500-ft3/s threshold generally precludes releases of higher flows that could be beneficial to the blue-ribbon trout fishery downstream in the Madison River. In response to concerns about minimizing streamflow downstream from Earthquake Lake and the possible armoring of the spillway, the USGS, in cooperation with the Madison River Fisheries Technical Advisory Committee (MADTAC; Bureau of Land Management; Montana Department of Environmental Quality; Montana Fish, Wildlife and Parks; PPL-Montana; U.S. Department of Agriculture Forest Service - Gallatin National Forest; and U.S. Fish and Wildlife Service), conducted a study to determine movement of the Madison River channel downstream from Earthquake Lake

  20. Introducing an R-package for calculating channel width and other basic metrics for irregular river polygons

    Science.gov (United States)

    Golly, Antonius; Turowski, Jens

    2017-04-01

    The width of fluvial streams and channel beds is an important metric for a large number of hydraulic, geomorphic and ecologic applications. For example, for a given discharge the local channel width determines the water flow velocity and thus the sediment transport capacity of a reach. Since streams often have irregular shapes with uneven channel banks, the channel width strongly varies along the channel. Although, the geometry of streams or their beds can be measured easily in the field (e.g. with a Total Station or GPS) or from maps or aerial images in a GIS, the width of the stream cannot be identified objectively without further data processing, since the results are more or less irregular polygons with sometimes bended shapes. An objective quantification of the channel width and other metrics requires automated algorithms that are applicable over a range of channel shapes and spatial scales. Here, we present a lightweight software suite with a small number of functions that process 2D or 3D geometrical data of channels or channel beds. The software, written as an R-package, accepts various text data formats and can be configured through five parameters. It creates interactive overview plots (if desired) and produces three basic channel metrics: the centerline, the channel width along the centerline and the slope along the centerline. The centerline is an optimized line that minimizes the distances to both channel banks. This centerline gives also a measure for the real length and slope of the channel. From this centerline perpendicular transects are generated which allow for the calculation of the channel width where they intersect with the channel banks. Briefly, we present an example and demonstrate the importance of these metrics in a use case of a steep stream, the Erlenbach stream in Switzerland. We were motivated to develop and publish the algorithm in an open-source framework, since only proprietary solutions were available at that time. The software is

  1. Wetted channel and bar features for the Tillamook, Trask, Wilson, Kilchis, and Miami Rivers, Oregon in 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  2. Wetted channel and bar features for the Tillamook, Trask, Wilson, Kilchis, and Miami Rivers, Oregon in 1939

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  3. Wetted channel and bar features for the Tillamook, Trask, Wilson, Kilchis, and Miami Rivers, Oregon in 1967

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  4. Wetted channel and bar features for the Tillamook, Trask, Wilson, Kilchis, and Miami Rivers, Oregon in 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Tillamook Bay subbasins and Nehalem River basins encompass 1,369 and 2,207 respective square kilometers of northwestern Oregon and drain to the Pacific Ocean....

  5. Analysis of Development of Channels Crossing Huangpu River in Shanghai Urban Area%上海中心城区越江隧道发展分析

    Institute of Scientific and Technical Information of China (English)

    周翔

    2012-01-01

      从黄浦江在上海城市发展中的重要性出发,依次分析了上海越江隧道建设在探索期、起步期和发展期的背景、意图和技术水平。从设施建设、交通运行与需求、交通量变化特征等方面剖析了现状越江隧道发展与城市的关系,并提出了未来上海中心城区的越江隧道规划设想。%  From the viewpoint of the position of Huangpu River in the development of Shanghai city, the background, view and technical level of channels crossing Huangpu River during exploring period, starting period and developing period are analyzed, with the aspects of facility construction, characteristics of traffic demand and volume, the relationship of development of current channels and urbanism. Future long-term planning scheme is also proposed.

  6. Testing river surveying techniques in tidal environments: example from an actively meandering channel surveyed with TLS (Mont Saint-Michel bay, France)

    Science.gov (United States)

    Leroux, J.; Lague, D.

    2013-12-01

    Tidal channel developed in mega-tidal salt marsh offer a unique set of characteristics to study the interaction between hydraulics, riparian vegetation and sedimentation using Terrestrial Laser Scanner (TLS). The recession of water allows a nearly complete survey of the channel that is otherwise impossible in rivers. Moreover, the predictability of tide amplitude allows to target surveys large events. Finally, the hydro-sedimentary processes and peak flow velocities in excess of 2 m/s in mega-tidal estuaries (e.g. Mont Saint Michel (MSM) bay) allow to explore conditions that are similar to river during flood conditions. This has motivated a 3 years study of a sinuous tidal channel located on the fringe of the marsh with the aim to understand its dynamics at daily to annual scales. We have acquired 36 high resolution topographic surveys with TLS, whose 13 daily surveys were acquired during annual largest tides. A local reference network of targets is used to yield a high registration accuracy with uncertainty varying between 1.5 mm and 3.4 mm. We use the CANUPO algorithm for classifying riparian vegetation and ground in 3D data, and use the point cloud comparison algorithm M3C2 to resolve 3D topographic changes down to 5 mm. ADCP, ADV and a turbidimeter were installed to constrain flow velocities and suspended sediment concentration (SSC). Our analysis is focused on three active compartments: (1) the inner bar on which riparian pioneer vegetation is developing and where sedimentation reaches up to 5 cm/tide; (2) the actively eroding outer bank which exhibits local retreat rates up to 2 m/tide; (3) the channel itself for which we document fluctuations of up to 0.2 m in elevation at daily to monthly timescales. We find that High Water Level (HWL) is a good predictor of the mean rate of evolution of these compartments with different empirical relationships. Spatially averaged sedimentation on the inner bend tends to increase linearly with HWL and is increased by a

  7. An integrated model coupling open-channel flow, turbidity current and flow exchanges between main river and tributaries in Xiaolangdi Reservoir, China

    Science.gov (United States)

    Wang, Zenghui; Xia, Junqiang; Li, Tao; Deng, Shanshan; Zhang, Junhua

    2016-12-01

    The ever growing importance of sustainable management of reservoir sedimentation has promoted the development and applications of turbidity current models. However, there are few effective and practical models in literature for turbidity currents in a reservoir where the impounded area involves both the main river and its many tributaries. An integrated numerical model coupling open-channel flow, turbidity current and flow exchanges between main river and tributaries is proposed, which can simulate the complex flow and sediment transport in a reservoir where these three physical processes coexist. The model consists of two sets of governing equations for the open-channel flow and turbidity current, which are based on the modified St. Venant equations by taking into account the effect of lateral flow exchanges. These two sets of equations are solved in the finite volume method framework and the solutions are executed in an alternating calculation mode. Different methods are respectively proposed to calculate the discharge of flow exchange caused by free surface gradient and turbidity current intrusion. For the surface-gradient driven flow exchange, a storage cell method, which re-defines the relationship between water level and representative cross-sectional area, is used to update the water level at confluence. For the turbidity current intrusion, a discharge formula is proposed based on the analysis of the energy and momentum transformation in the intruding turbid water body. This formula differs from previous ones in that the effect of tributary bed slope is considered. Two events of water-sediment regulation conducted in the Xiaolangdi Reservoir in 2004 and 2006 were simulated to test the ability of this model. The predicted reservoir drawdown process, the turbidity current evolution and the sediment venting efficiency were in close agreement with the measurements. The necessity to couple the flow exchanges was demonstrated by comparing the performance of the

  8. Ecological hydrograph based on Schizothorax chongi habitat conservation in the dewatered river channel between Jinping cascaded dams

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Hydropower development changes the river hydrological regime,thereby altering river ecosystem significantly.One important measure for reducing degradation of ecosystem is to determine ecological flow and implement it by reservoir operation.This paper described a method to calculate river ecological flow based on fish habitat conservation and applied it to Jinping River Bend of Yalong River.Schizothorax chongi was selected as target species,and the fish habitat model coupling with water environmental model was developed according to the relationship between fish and water environment factors.Moreover,improved hydraulic habitat suitability index(IHHS) and habitat fragment index(HFI) varying with discharge were discussed in this paper.Habitat area representing average annual flow was taken as a reference,and then ecological hydrographs under different habitat conservation levels were calculated considering season variation and life stages of fish.Compared to the natural condition,the model results indicated that the reservoir operation clearly influenced the habitat of the target fish.It was proposed to ensure flow releases to maintain 70%-90% habitat in section after joint while about 60% before joint.

  9. Analysis of the Profitability and Marketing Channels of Rice: A Case Study of Menchum River Valley, North-West Region, Cameroon

    Directory of Open Access Journals (Sweden)

    Bime, M. J.

    2014-06-01

    Full Text Available The study carried out in Menchum River valley, Northwest Region of Cameroon had as objective to analyze the profitability and establish the marketing channels of rice in this zone. The study in-terviewed a total of 126 respondents, selected purposively and using the snow ball sampling tech-nique. Results showed that the main actors involved in the rice marketing channel were; produc-ers, wholesalers, hullers, retailers and consumers. The production and marketing of rice in the zone is a profitable venture. In terms of profitability in the rice business, millers obtain a relatively large profit margin as a percentage of the cost price (18.69% followed by the producers (12.77%, wholesalers (8.5% then retailers (8.33%. The average profit margin per bag of 50kg was; 1054.5FCFA (franc Communauté financière d'Afrique for producers, 1963.5 FCFA for millers; 1100 FCFA for the wholesalers and 1250FCFA for the retailers. The principal constraints identi-fied by the study that affects actors of the rice channel were, bad condition of the roads, lack of capital, poor quality of rice. It was recommended that there should be improvement in infrastruc-ture.

  10. Characterization of channel substrate, and changes in suspended-sediment transport and channel geometry in white sturgeon spawning habitat in the Kootenai River near Bonners Ferry, Idaho, following the closure of Libby Dam

    Science.gov (United States)

    Barton, Gary J.

    2004-01-01

    Many local, State, and Federal agencies have concerns over the declining population of white sturgeon (Acipenser transmontanus) in the Kootenai River and the possible effects of the closure and subsequent operation of Libby Dam in 1972. In 1994, the Kootenai River white sturgeon was listed as an Endangered Species. A year-long field study was conducted in cooperation with the Kootenai Tribe of Idaho along a 21.7-kilometer reach of the Kootenai River including the white sturgeon spawning reach near Bonners Ferry, Idaho, approximately 111 to 129 kilometers below Libby Dam. During the field study, data were collected in order to map the channel substrate in the white sturgeon spawning reach. These data include seismic subbottom profiles at 18 cross sections of the river and sediment cores taken at or near the seismic cross sections. The effect that Libby Dam has on the Kootenai River white sturgeon spawning substrate was analyzed in terms of changes in suspended-sediment transport, aggradation and degradation of channel bed, and changes in the particle size of bed material with depth below the riverbed. The annual suspended-sediment load leaving the Kootenai River white sturgeon spawning reach decreased dramatically after the closure of Libby Dam in 1972: mean annual pre-Libby Dam load during 1966–71 was 1,743,900 metric tons, and the dam-era load during 1973–83 was 287,500 metric tons. The amount of sand-size particles in three suspended-sediment samples collected at Copeland, Idaho, 159 kilometers below Libby Dam, during spring and early summer high flows after the closure of Libby Dam is less than in four samples collected during the pre-Libby Dam era. The supply of sand to the spawning reach is currently less due to the reduction of high flows and a loss of 70 percent of the basin after the closure of Libby Dam. The river's reduced capacity to transport sand out of the spawning reach is compensated to an unknown extent by a reduced load of sand entering the

  11. Influence of hydrological regime and land cover on traits and potential export capacity of adult aquatic insects from river channels.

    Science.gov (United States)

    Greenwood, M J; Booker, D J

    2016-02-01

    Despite many studies highlighting the widespread occurrence and effects of resource movement between ecosystems, comparatively little is known about how anthropogenic alterations to ecosystems affect the strength, direction and importance of such fluxes. Hydrological regime and riparian land use cause well-documented changes in riverine larval invertebrate communities. Using a dataset from 66 sites collected over 20 years, we showed that such effects led to spatial and temporal differences in the density and type of larvae with winged adults within a river reach, altering the size and composition of the source pool from which adult aquatic insects can emerge. Mean annual larval densities varied 33-fold and the temporal range varied more than 20-fold between sites, associated with the hydrological regime and land cover and antecedent high and low flows, respectively. Densities of larvae with winged adults were greater in sites that had more algal coverage, agricultural land use, seasonally predictable flow regimes and faster water velocities. More interestingly, by influencing larval communities, riparian land use and the magnitude and frequency of high and low flows affected the size structure, dispersal ability and longevity of adults available to emerge from river reaches, potentially influencing the spatial extent and type of terrestrial consumers supported by aquatic prey. This suggests that anthropogenic alterations to land use or river flows will have both spatial and temporal effects on the flux and potential availability of adult aquatic insects to terrestrial consumers in many rivers.

  12. Interim Feasibility Report and Draft Environmental Impact Statement, Grays Harbor, Chehalis and Hoquiam Rivers, Washington, Channel Improvements for Navigation.

    Science.gov (United States)

    1982-06-01

    square miles and includes the Chehalis, Hoquiam, Wishkah, Hnp- tulips , Johns, 1nd Elk River basins. The Chehalis is the largest ri~er system, contribrting...al., 1980). 13 A myriad of organisms inhabit eelgrass beds. Benthic fauna include nereid worms, clams, nematodes , and burrowing anemones. The leaves

  13. Reconstruction of the Late Holocene river channel shifts in the North-Eastern part of the Lower Danube Plain based on historical data

    Directory of Open Access Journals (Sweden)

    Ionuț-Alexandru CRISTEA

    2014-11-01

    s floodplain (until the confluence with Buzău it is larger by a couple of kilometers than Danube’s, despite the anastomosed character of the last one. This can indicate a progressive Holocene shift of the Siret’s river course from the Carpathians to the eastern edge of the floodplain or a transformation from a multi-channel to a single channel pattern. The instability was also specific to main tributaries, as is confirmed by the presence of multiple abandoned sinuous courses and relict meander belts in the area. An important shift of the Siret River’s lower course to a more eastern position during medieval times was briefly discussed, for the first time, by Antonovici (1929 based on couple of historical documents. The few questions we will try to answer to in this study are: When was formed the actual configuration of the river network in the study region? What was the impact of the LIA? How relevant can be the analysis of the historical data in the assessment of the river channel shifts?

  14. Rapid incision of the Colorado River in Glen Canyon - insights from channel profiles, local incision rates, and modeling of lithologic controls

    Science.gov (United States)

    Cook, K.L.; Whipple, K.X.; Heimsath, A.M.; Hanks, T.C.

    2009-01-01

    The Colorado River system in southern Utah and northern Arizona is continuing to adjust to the baselevel fall responsible for the carving of the Grand Canyon. Estimates of bedrock incision rates in this area vary widely, hinting at the transient state of the Colorado and its tributaries. In conjunction with these data, we use longitudinal profiles of the Colorado and tributaries between Marble Canyon and Cataract Canyon to investigate the incision history of the Colorado in this region. We find that almost all of the tributaries in this region steepen as they enter the Colorado River. The consistent presence of oversteepened reaches with similar elevation drops in the lower section of these channels, and their coincidence within a corridor of high local relief along the Colorado, suggest that the tributaries are steepening in response to an episode of increased incision rate on the mainstem. This analysis makes testable predictions about spatial variations in incision rates; these predictions are consistent with existing rate estimates and can be used to guide further studies. We also present cosmogenic nuclide data from the Henry Mountains of southern Utah. We measured in situ 10Be concentrations on four gravel-covered strath surfaces elevated from 1 m to 110 m above Trachyte Creek. The surfaces yield exposure ages that range from approximately 2??5 ka to 267 ka and suggest incision rates that vary between 350 and 600 m/my. These incision rates are similar to other rates determined within the high-relief corridor. Available data thus support the interpretation that tributaries of the Colorado River upstream of the Grand Canyon are responding to a recent pulse of rapid incision on the Colorado. Numerical modeling of detachment-limited bedrock incision suggests that this incision pulse is likely related to the upstream-dipping lithologic boundary at the northern edge of the Kaibab upwarp. ?? 2009 John Wiley & Sons, Ltd.

  15. Evolution Analysis of Minqing Channel in the Lower Reach of Minjiang River%闽江下游闽清河段河道演变分析

    Institute of Scientific and Technical Information of China (English)

    叶丽清; 胡朝阳; 王新强

    2014-01-01

    Minqing channel is situated at the lower reaches of Minjiang River ,due to the construction of the reservoir , sand excavation in river courses and waterway regulation ,the changes of the flow and sediment conditions and the evolu-tion of the riverbed are relatively strong ,which causes frequent riverbank collapses .These accidents affect the livelihood of people who live along the channel .Based on the measured topographic data of Minqing channel ,the evolution charac-teristics was analysed from aspects of the overall terrain variations ,the changes in thalweg and cross-section morphology , etc .The results showed that the evolution of Minqing channel in late decades were mainly in longitudinal scour with sig-nificant depth ;the influential factors of evolution include the channel morphology and riverbed border ,the construction of the reservoir ,the sand excavation ,the near-shore projects ,the big floods ,the inflow of branches and the tidal jacking . According to the change trend of the influential factors ,it is predicted that the evolution trend of Minqing channel will still mainly be longitudinal scour over a period of time in the future ,and the foundation of the near-shore projects should be protected and reinforced .%闽清河段位于闽江下游,受水库建设、河道采砂及航道整治等人类活动影响,水沙条件变化和河床演变较为剧烈,崩岸事故频发,给沿岸人民的生产、生活等带来较大影响。依据河道实测地形资料,从河道平面、深泓线变化及河床断面形态等方面对该河段的演变特征进行了分析。结果表明:受河道两岸山体及河中丁坝群制约,闽清河段平面变化受到限制,历年来的演变以纵向的刷深为主,且刷深幅度明显;其演变受到河道形态与河床边界、水库建设、河道采砂、涉河工程建设、大洪水、支流入汇及潮汐顶托等多个因素的影响;结合演变影响因素的变化

  16. Thinking on Flood Control Problems of Communism Channel Hehe River to Liuzhuang Gate Section%共产主义渠合河至刘庄闸段防洪问题的思考

    Institute of Scientific and Technical Information of China (English)

    申继先

    2014-01-01

    共产主义渠属海河流域漳卫河水系,卫河支流,是流域防洪体系的重要组成部分。共产主义渠防汛工作事关新乡市、卫辉市等城市和沿河村镇人民生命财产安全及京广铁路、石武高铁、京珠高速等重要设施的安全。本文对共产主义渠合河-刘庄闸段防洪工程的现状和存在问题展开分析,对做好该段河道防洪保安提出对策和建议。%Communism-Channel-belongs-to-Zhangwei-River-Water-System-in-Haihe-River-Basin-,-which-is-a-branch-of-Weihe-River-and-important-part-of-river-basin-flood-control-system-.Communism-Channel-flood-control-work-is-related-to-life-and-property-safety-of-people-in-Xinxiang-,-Weihui-and-other-cities-as-well-as-villages-and-towns-along-the-river-.It-also-relates-to-safety-of-Beijing-Guangzhou-Railway-,-Shijiazhuang-Wuhan-High-speed-Railway-,-Beijing-Zhuhai-Expressway-and-other-important-facilities-.In-the-paper-,-current-situation-and-problems-in-Communism-Channel-Hehe-River-to-Liuzhuang-Gate-Section-are-analyzed-,-countermeasures-and-suggestions-are-proposed-aiming-at-flood-control-and-guard-in-the-river-section-.

  17. Interacting effects of discharge and channel morphology on transport of semibuoyant fish eggs in large, altered river systems.

    Directory of Open Access Journals (Sweden)

    Thomas A Worthington

    Full Text Available Habitat fragmentation and flow regulation are significant factors related to the decline and extinction of freshwater biota. Pelagic-broadcast spawning cyprinids require moving water and some length of unfragmented stream to complete their life cycle. However, it is unknown how discharge and habitat features interact at multiple spatial scales to alter the transport of semi-buoyant fish eggs. Our objective was to assess the relationship between downstream drift of semi-buoyant egg surrogates (gellan beads and discharge and habitat complexity. We quantified transport time of a known quantity of beads using 2-3 sampling devices at each of seven locations on the North Canadian and Canadian rivers. Transport time was assessed based on median capture time (time at which 50% of beads were captured and sampling period (time period when 2.5% and 97.5% of beads were captured. Habitat complexity was assessed by calculating width∶depth ratios at each site, and several habitat metrics determined using analyses of aerial photographs. Median time of egg capture was negatively correlated to site discharge. The temporal extent of the sampling period at each site was negatively correlated to both site discharge and habitat-patch dispersion. Our results highlight the role of discharge in driving transport times, but also indicate that higher dispersion of habitat patches relates to increased retention of beads within the river. These results could be used to target restoration activities or prioritize water use to create and maintain habitat complexity within large, fragmented river systems.

  18. The modeling of the channel deformations in the rivers flowing into permafrost with an increase in ambient temperature

    Science.gov (United States)

    Debolskaya, E. I.; Zamjatina, E. V.; Gritsuk, I. I.; Maslikova, O. Ja.

    2012-04-01

    Global climate changes in recent decades inevitably lead to more frequent catastrophic events. Their negative effects on rivers flowing into the permafrost zone, may be exacerbated by significant changes in bed deformations caused not only the influence of water flow, but significant changes of the bed due to the influence of increasing water and air temperatures on the structure of its constituent materials. The coastal slopes composed of permafrost will be subject to thermal abrasion. The purpose of this paper is to investigate the influence of river flow during the increase of water temperature on the deformation of the coastal slopes, composed of permafrost rocks with the addition of ice layers. The method of investigation is laboratory and mathematical modeling. The basis of the three-dimensional mathematical model of the coastal slopes thermoerosion of the rivers flowing in permafrost regions, and its verification is the results of the laboratory experiments conducted in the hydraulic tray. When the water temperature in the main stream rises the ice plate begins to melt forming the cavity where small streams are formed. The soil layers lose hard icy base and begin to sag under gravity. In the mathematical model law of the phase transition movement (Stefan condition) is determined from the heat balance equation. To determine the longitudinal velocity and the turbulent exchange coefficient we use the approach of "shallow water". The value of the transverse velocity is calculated from the equation of continuity. Coastal slope deformation during thawing is determined primarily by deposition of rock under the influence of gravity. An erosion due to water current in the mainstream and in the cavities may play a role under sufficient looseness of the rocks. The parameterization of the rocks deposition is almost impossible without knowing the composition of the soil, its porosity, ice content, moisture content. The determination of the rate and amount of slipping is

  19. Operation and Maintenance, 9-Foot Navigation Channel, Upper Mississippi River, Head of Navigation to Guttenberg, Iowa. Volume 2. Exhibits.

    Science.gov (United States)

    1974-08-01

    Falls 196 Impacts and Effects of Alternative Management Plans for 223 Operation and Maintenance of Nine-Foot Navigation Channel Pool 1 xii TABLE OF...DNUMBTPULEONRCR IPE TINICTE HWDRULI DUST PANY QREDGE HDSTRICA TABLA SUMMRY O THE"SLN LOATON VOLUMEC ANERQEC VOL DREDDEE ST00 PAUL OFNRAT DREDGIN INPON...C 4.C tt0 na a-at W"a- 4. t0 o I It E On N a co .tltt.C 084t-C .0 00 88 o. E~s. 3 ttt. ttttt tC~~ t 9 R T. PAULtttt DISRIC S XII 2 FODVLMS RBTR TEM N

  20. Estimates of Deep Percolation Beneath Native Vegetation, Irrigated Fields, and The Amargosa-River Channel, Amargosa Desert, Nye County, Nevada

    Science.gov (United States)

    2003-01-01

    infrequent because precipitation averages less than 150 mm per year over much of the drainage area ( Tanko and Glancy, 2001). Flow in the channel is...of March 11, 1995 and February 23- 24, 1998 ( Tanko and Glancy, 2001; Beck and Glancy, 1995). Peak flows associated with the 1998 flood were estimated...and 20 cfs (0.6 m3/s) near Big Dune ( Tanko and Glancy, 2001). These estimates indicate that 70 cfs (2.0 m3/s) of flow was lost along the reach

  1. The importance of fine-grained channel margin (FGCM) deposits in assessing the multiple residence times of suspended sediment and contaminants in gravel-bed rivers

    Science.gov (United States)

    Skalak, K. J.; Pizzuto, J. E.

    2008-12-01

    We have found that fine-grained channel margin (FGCM) deposits conditioned by large woody debris (LWD) are a significant component of sediment budgets in agricultural watersheds. By volume, the deposits store about 28 percent of the annual suspended sediment load. Radiocarbon, Pb-210, and Cs-137 analyses indicate a range of sediment ages (1 year to several decades). Reservoir theory analysis indicates an average turnover time of 1.5 years and an annual mass flux equivalent to 5 percent of the annual sediment load. The power function that best fits the transit time distribution suggests that there are multiple transit times and that most sediment in the deposits is reworked on short timescales, but a portion remains in place for several decades or more. The presence of a long tail in the distribution suggests anomalous transport, which indicates a well-developed framework for subsurface contaminant transport, continuous time random walks (CTRW), could be utilized for suspended sediment transport and contaminants associated with suspended sediment. South River has a history of mercury (Hg) contamination from an industrial release that occurred 1930-1950. The distribution of ages and Hg concentrations suggest that approximately 10 percent of the sediment and 75 percent of the Hg in the deposits dates from the release period. If the sediment in FGCM deposits has been transported primarily in suspension then we can reconstruct the loading history of Hg from the plant and predict that centuries will be required to remove this material. Our approach can be generalized to assess storage of sediments and contaminants in other gravel-bed rivers.

  2. Missouri River 1943 Compact Line

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Flood Control, Bank Stabilization and development of a navigational channel on the Missouri River had a great impact on the river and adjacent lands. The new...

  3. Channel re-establishment of the Lower Yellow River in ten years operation of Xiaolangdi Reservoir%小浪底水库运用十年黄河下游河道的再造床

    Institute of Scientific and Technical Information of China (English)

    陈建国; 周文浩; 陈强

    2012-01-01

    The Xiaolangdi Hydro-Project is a large project downstream of the Sanmenxia Project in the Yel- low River playing the role of flood control and sedimentation mitigation. The reservoir has been operated for 10 years. Based on the field measured data, the reservoir sedimentation and the channel re-establishment of the Lower Yellow River including the morphology of the reservoir deposition, the density current and its sediment transport, the characteristics and efficiency of channel erosion, the coarsening of bed sediment and effects of channel armoring, the relationship between reservoir deposition and channel erosion, as well as the compensation index of reservoir deposition, are analyzed and expounded in this paper. These results are helpful to understand the new behavior of fluvial processes of the river carrying large amount of sediment load such as the Yellow River in the initial period of reservior operation.%天然河流上游修建大型水利枢纽后,必将引起水库下游河道的再造床。黄河小浪底水库自1999年10月下旬下闸蓄水以来,已运行十年有余。本文通过实测资料的分析,从河道的冲刷和河道的平面形态变化两方面来阐明小浪底水库拦沙运用十年来水库淤积及下游河道的再造床过程及其特点,为小浪底水库进一步水沙调控提供借鉴,也丰富了多泥沙河流兴建大型水库以后下游河道河床演变学科的内涵。

  4. Fine sediment transport by tidal asymmetry in the high-concentrated Ems River: indications for a regime shift in response to channel deepening

    NARCIS (Netherlands)

    Winterwerp, J.C.

    2010-01-01

    This paper describes an analysis of the observed up-river transport of fine sediments in the Ems River, Germany/Netherlands, using a 1DV POINT MODEL, accounting for turbulence-induced flocculation and sediment-induced buoyancy destruction. From this analysis, it is inferred that the net up-river tra

  5. DEBRIS FLOW EVENT OF 2014 AND ITS IMPACT ON THE ACCUMULATION OF THE SOLID FRACTION IN THE KYNGARGA RIVER CHANNEL, TUNKA VALLEY, SOUTHWESTERN CISBAIKALIA, RUSSIA

    OpenAIRE

    KADETOVA ARTEM A.; RYBCHENKO ELENA A.; KOZYREVA ELENA A.; YONGBO TIE; HUAYONG NI

    2016-01-01

    On 28 June 2014, debris flows brought large volumes of loose material into the Kyngarga river valley. The material was sourced from rock collapse and rock sliding on the valley slopes and delivered mainly to the river by debris flows from the side valleys of the river basin. Our field studies and analysis of the satellite images revealed that the potential debris volume received by the river amounted to about 1x106 m3. The morphometric parameters of the Kyngarga river basin are favorable for ...

  6. Acid Volatile Sulfides (avs) and the Bioavailability of Trace Metals in the Channel of the SÃO Francisco River, Sepetiba Bay - de Janeiro-Brazil

    Science.gov (United States)

    Monte, Christiane; Rodrigues, Ana Paula; Marinho, Matheus; Quaresma, Tássia; Machado, Wilson

    2014-05-01

    Sepetiba Bay has 430 Km2 of internal and 2,500 Km2 area of the drainage basin (Lacerda et al., 2007), located 60 km west of the city of Rio de Janeiro. Sepetiba Bay has 430 Km2 of internal and 2,500 Km2 area of the drainage basin (Lacerda et al., 2007), located 60 km west of the city of Rio de Janeiro.The San Francisco channel comes from the Guandu River and empties into Sepetiba Bay and is the main contributor of freshwater to the estuarine system. The Guandu River system/channel of San Francisco receives contribution of domestic and industrial effluents, which go largely to Sepetiba Bay. This work aimed to evaluate the .This work aimed to evaluate the ratio SEM/AVS as a way of predicting bioavailability trace metals from industrial sewage, mainly, in the estuarine system of Sepetiba. This model is based on the property of some Divalent metal cations (Cd, Cu, Ni, Pb and Zn), by presenting a low solubility constant, are removed from the soluble fraction by precipitation, forming secondary metal sulfides. Were held four transects, made up of three points each, the coast line to the center of the Bay. The surface sediment was collected with a van Veen sampler type ,packed in glass jars and kept frozen until analysis.The determination of SEM/AVS followed the methodology described by Allen et al. (1991). The variation between sulfide 159.88 ± 0.05 µmol/g on 12 points. The metals that entered the sum of simultaneous extraction were: Cd, Cu, Ni, Pb and Zn ranging from: 6.47 ± 0.11 µmol/g on sum.The means (± standard deviation) ratio SEM/AVS per transect were: 1.04 ± 1.20 (transect 1); 0.48 ± 0.53 (transect 2); 1.26 ± 1.32 (transect 3) and 0.18 ± 0.14 (transect 4). Only transects 1 and 3 had higher results than 1 , meaning that there are more divalent metal sulfides in the environment. This means that only the sulfides would not be capable of complex and may reflect the potential bioavailability of these in the aquatic environment. There is no statistical

  7. The vertical distribution of selected trace metals and organic compounds in bottom materials of the proposed lower Columbia River export channel, Oregon, 1984

    Science.gov (United States)

    Fuhrer, Gregory J.; Horowitz, Arthur J.

    1989-01-01

    A proposal to deepen the lower Columbia River navigation channel in Oregon prompted a study of the vertical distribution of selected trace metals and organic compounds in bottom sediments. These data are needed to evaluate the effects of dredging and disposal operations. Elutriation testing of bottom material indicated chemical concentrations as large as 900 ug/L for barium, 6,500 ug/L for manganese, and 14 ug/L for nickel. The amount of oxygen present during elutriation testing of reduced bottom material was shown to have a negligble effect on manganese elutriate-test concentrations, but it did affect barium and iron concentrations. Sediment-associated organochlorine compounds detected in bottom-sediment core samples were as large as 0.1 ug/kg (micrograms/kilogram) for aldrin, 2.0 ug/kg for chlordane, 27 ug/kg for DDD, 5.0 ug/kg for DDE, 0.2 ug/kg for DDT, 0.2 ug/kg for dieldrin, 37 ug/kg for PCB 's 1.0 ug/kg for PCN 's and 1.0 ug/kg for heptachlor epoxide. Concentrations of cadmium, lead, and zinc in selected cores were found to exceed those of local basalts. Concentrations of cadmium, lead, and zinc were as large as 3.6 ug/g, 26 ug/g, and 210 ug/g respectively. Bottom-sediment concentrations of cadmium , chromium, copper, iron, and zinc associated with the less-than-100-micrometer size fraction are larger than those associated with the greater-than-100-micrometer fraction. (USGS)

  8. Use of navigation channels by Lake Sturgeon: Does channelization increase vulnerability of fish to ship strikes?

    Science.gov (United States)

    Bennion, David H.; Roseman, Edward F.; Holbrook, Christopher M.; Boase, James C.; Chiotti, Justin A.; Thomas, Michael V.; Wills, Todd C.; Drouin, Richard G.; Kessel, Steven T.; Krueger, Charles C.

    2017-01-01

    Channelization for navigation and flood control has altered the hydrology and bathymetry of many large rivers with unknown consequences for fish species that undergo riverine migrations. In this study, we investigated whether altered flow distributions and bathymetry associated with channelization attracted migrating Lake Sturgeon (Acipenser fulvescens) into commercial navigation channels, potentially increasing their exposure to ship strikes. To address this question, we quantified and compared Lake Sturgeon selection for navigation channels vs. alternative pathways in two multi-channel rivers differentially affected by channelization, but free of barriers to sturgeon movement. Acoustic telemetry was used to quantify Lake Sturgeon movements. Under the assumption that Lake Sturgeon navigate by following primary flow paths, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River were expected to choose navigation channels over alternative pathways and to exhibit greater selection for navigation channels than conspecifics in the less-channelized lower St. Clair River. Consistent with these predictions, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River selected the higher-flow and deeper navigation channels over alternative migration pathways, whereas in the less-channelized lower St. Clair River, individuals primarily used pathways alternative to navigation channels. Lake Sturgeon selection for navigation channels as migratory pathways also was significantly higher in the more-channelized lower Detroit River than in the less-channelized lower St. Clair River. We speculated that use of navigation channels over alternative pathways would increase the spatial overlap of commercial vessels and migrating Lake Sturgeon, potentially enhancing their vulnerability to ship strikes. Results of our study thus demonstrated an association between channelization and the path use of migrating Lake Sturgeon that could prove important for

  9. Using 10Be erosion rates and fluvial channel morphology to constrain fault throw rates in the southwestern Sacramento River Valley, California, USA

    Science.gov (United States)

    Cyr, A. J.

    2013-12-01

    The Sacramento - San Joaquin River Delta, California, USA, is a critical region for California water resources, agriculture, and threatened or endangered species. This landscape is affected by an extensive set of levees that enclose artificial islands created for agricultural use. In addition to their importance for sustaining agriculture, this levee system also supports extensive transport and power transmission infrastructure and urban/suburban development. These levees are susceptible to damage from even moderate ground shaking by either a large earthquake on one of the high-activity faults in the nearby San Francisco Bay region, or even a moderate earthquake on one of the low-activity faults in the Delta region itself. However, despite this danger the earthquake hazards in this region are poorly constrained due to our lack of understanding of faults in and near the Delta region. As part of an effort to better constrain the seismic hazard associated with known, but poorly constrained, faults in the region, a geomorphic analysis of the Dunnigan Hills, northwest of Woodland, CA, is being combined with cosmogenic 10Be catchment-averaged erosion rates. The Dunnigan Hills are a low-relief (maximum elevation 87 m) landscape generated by fault-bend folding above the west-vergent Sweitzer reverse fault that soles into a blind east-vergent reverse fault. These faults have been imaged by seismic reflection data, and local microseismicity indicates that this system is actively propagating to the east. However, the throw rates on the faults in this system remain unconstrained, despite the potential for significant shaking such as that experienced in the nearby April, 1892 earthquake sequence between Winters and Vacaville, Ca, ~25 km to the south, which has been estimated at magnitude 6.0 or greater. Geomorphic and cosmogenic 10Be analyses from 12 catchments draining the eastern flank of the Dunnigan Hills will be used to infer vertical rock uplift rates to better constrain

  10. Technical Note: Automatic river network generation for a physically-based river catchment model

    OpenAIRE

    2010-01-01

    SHETRAN is a physically-based distributed modelling system that gives detailed simulations in time and space of water flow and sediment and solute transport in river catchments. Standard algorithms for the automatic generation of river channel networks from digital elevation data are impossible to apply in SHETRAN and other similar models because the river channels are assumed to run along the edges of grid cells. In this work a new algorithm for the automatic generation of a river channel ne...

  11. 长江上游叙渝段弯道平面形态及碍航特征∗%Plane configuration and navigation-obstructing characteristics of curved channels in Yibin-Chongqing reach of upper Yangtze River

    Institute of Scientific and Technical Information of China (English)

    王梅力; 陈秀万; 王平义; 林孝松

    2015-01-01

    基于对长江上游宜宾至重庆主城区河段25个主要弯道平面形态特征的统计分析,研究弯曲河段扩宽率、收缩率、弯曲度、弯道中心角、曲颈河宽与平均河宽比、弯顶中心半径与平均河宽比等特征值的变化规律。结果表明:在平面形态上,大部分弯道呈现两头窄、中间宽的形态特征,部分弯道急剧弯曲、展宽凹陷非常明显;弯道中心角一般在60°~130°范围内,且大部分弯道中心角≥90°;大部分河湾的弯曲度>1.2。分析弯道平面形态的形成机理和碍航特点。研究成果对港航工程、水利工程、市政工程和生态环境工程等的规划和建设具有参考价值。%Based on the analysis of the plane configuration characteristics of 25 main curved channels in Yibin-Chongqing reach of the upper Yangtze River, we probes into the changing rules of characteristic parameters as follows:the curved reach expanding rate, shrinkage rate, bending, bend angle at centre, ratio between swan river width and average river width, ratio between radius of center at curved top and average river width of characteristic value change rule. The results show that most curved channels are narrow at both ends and wide in the middle part, some curved channels are sharp bend and very apparent broadening and sag; the bend angles in the centre are between 60 ° and 130 ° , and most bends” central angle is greater than or equal to 90 °;the sinuosity of most curved channels is over 1. 20 . The navigation-obstructing characteristics and forming mechanism of the bend plane morphology are also analyzed. The above results may serve as reference for the planning and construction of port and waterway engineering, hydraulic engineering, municipal engineering and ecological engineering, etc.

  12. 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.

    Science.gov (United States)

    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

  13. The Ecological Reserve: Towards a common understanding for river ...

    African Journals Online (AJOL)

    ... Towards a common understanding for river management in South Africa. ... functions is directly aligned with options for human use arising from rivers to deliver ... of water and associated resources located within the macro channels of rivers, ...

  14. Analysis of Channel Evolution in Fu River Tail and Poyang Estuary Based on Remote Sensing Technology%基于遥感的抚河尾闾及入鄱阳湖口演变分析

    Institute of Scientific and Technical Information of China (English)

    章重; 张秀平; 田佳; 雷声; 李伊林

    2013-01-01

    基于遥感和地理信息系统技术,以1973--2009年的鄱阳湖枯水期遥感影像作为主要数据源,利用影像分类原理提取抚河尾闾及入湖口的河道滩地信息,研究40年来河道滩地的演变规律,并分析引起形态变化的主要因素。具体为:通过定量和矢量叠加方法提取抚河尾闾河道及入湖口的平面形态特征,结果表明,抚河尾闾青岚湖入口处心洲扩,河道东移,河段滩地交替演变,部分河道顺直,入湖口具有河口淤高湖和岸线向湖中心推进的特点;演变受自然和人为因素的影响,其中河道采沙、航道疏浚、植树造林等人为活动影响更大。研究结果对抚河尾闾的河势控制、河道整治及岸线开发利用、生态环境保护提供技术支持。%Based on remote sensing technology and GIS technology, this paper collects the representative remote sensing images of dry season from 1973 to 2009 in Poyang Lake as main data source. It uses image classification principle to extract channel information of Fu river tail and estuary. It studies the evolvement rule of river shoal evolution in recent 40 years, and analyzes the main factors influencing the morphological changes. The specific is through the method of quantification and vector superposition to extract the surface morphological characteristics of Fu river trail channel and estuary. The result shows that the heart state in extrance of QingLan lake expanding, the river eastward-moving, the river and shoal evoluting alternately, part of river straight. The characteristics of the estuary include estuary silt piled high and shoreline propulsion to the lake center. Evolution is affected by natural and human factors, of which the river sand, waterway dredging, afforestation and other human activities influence is greater. This study result provides technical support for the river regime control, river regulation and exploitation and utilization of coastline

  15. Downstream hydraulic geometry of a tidally influenced river delta

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Brye, de B.; Deleersnijder, E.

    2012-01-01

    Channel geometry in tidally influenced river deltas can show a mixed scaling behavior between that of river and tidal channel networks, as the channel forming discharge is both of river and tidal origin. We present a method of analysis to quantify the tidal signature on delta morphology, by extendin

  16. Criteria for the Depths of Dredged Navigational Channels.

    Science.gov (United States)

    1983-05-01

    240,000 DWT supertanker Lepton sailing in the Eurooport channels. Extensive investigations were also made in the Chao Phraya River , Bangkok, and along...increasing the probability of grounding or striking bottom. The panel emphasizes that these results *Calcasieu River (inner and outer channels), Lower...Columbia River , Delaware River , Mobile Harbor, Norfolk Harbor, Oakland Harbor, San Francisco Bay, Thimble Shoal, and Galveston Channel 6L E-3 are more

  17. Laminar laboratory rivers

    Science.gov (United States)

    Seizilles, Grégoire; Devauchelle, Olivier; Lajeunesse, Éric; Métivier, François

    2014-05-01

    A viscous fluid flowing over fine plastic grains spontaneously channelizes into a few centimeters-wide river. After reaching its equilibrium shape, this stable laboratory flume is able to carry a steady load of sediments, like many alluvial rivers. When the sediment discharge vanishes, the river size, shape and slope fit the threshold theory proposed by Glover and Florey (1951), which assumes that the Shields parameter is critical on the channel bed. As the sediment discharge is increased, the river widens and flattens. Surprisingly, the aspect ratio of its cross section depends on the sediment discharge only, regardless of the water discharge. We propose a theoretical interpretation of these findings based on the balance between gravity, which pulls particles towards the center of the channel, and the diffusion of bedload particles, which pushes them away from areas of intense bedload.

  18. Synthetic River Valleys

    Science.gov (United States)

    Brown, R.; Pasternack, G. B.

    2011-12-01

    The description of fluvial form has evolved from anecdotal descriptions to artistic renderings to 2D plots of cross section or longitudinal profiles and more recently 3D digital models. Synthetic river valleys, artificial 3D topographic models of river topography, have a plethora of potential applications in fluvial geomorphology, and the earth sciences in general, as well as in computer science and ecology. Synthetic river channels have existed implicitly since approximately the 1970s and can be simulated from a variety of approaches spanning the artistic and numerical. An objective method of synthesizing 3D stream topography based on reach scale attributes would be valuable for sizing 3D flumes in the physical and numerical realms, as initial input topography for morphodynamic models, stream restoration design, historical reconstruction, and mechanistic testing of interactions of channel geometric elements. Quite simply - simulation of synthetic channel geometry of prescribed conditions can allow systematic evaluation of the dominant relationships between river flow and geometry. A new model, the control curve method, is presented that uses hierarchically scaled parametric curves in over-lapping 2D planes to create synthetic river valleys. The approach is able to simulate 3D stream geometry from paired 2D descriptions and can allow experimental insight into form-process relationships in addition to visualizing past measurements of channel form that are limited to two dimension descriptions. Results are presented that illustrate the models ability to simulate fluvial topography representative of real world rivers as well as how channel geometric elements can be adjusted. The testing of synthetic river valleys would open up a wealth of knowledge as to why some 3D attributes of river channels are more prevalent than others as well as bridging the gap between the 2D descriptions that have dominated fluvial geomorphology the past century and modern, more complete, 3D

  19. Where does all the water go? Partitioning water transmission losses in a data-sparse, multi-channel and low-gradient dryland river system using modelling and remote sensing

    Science.gov (United States)

    Jarihani, Abdollah A.; Larsen, Joshua R.; Callow, John N.; McVicar, Tim R.; Johansen, Kasper

    2015-10-01

    Drylands cover approximately one-third of the Earth's surface, are home to nearly 40% of the Earth's population and are characterised by limited water resources and ephemeral river systems with an extremely variable flow regime and high transmission losses. These losses include actual evaporation, infiltration to the soil and groundwater and residual (terminal) water remaining after flood events. These critical components of the water balance of dryland river systems remain largely unknown due to the scarcity of observational data and the difficulty in accurately accounting for the flow distribution in such large multi-channel floodplain systems. While hydrodynamic models can test hypotheses concerning the water balance of infrequent flood events, the scarcity of flow measurement data inhibits model calibration, constrains model accuracy and therefore utility. This paper provides a novel approach to this problem by combining modelling, remotely-sensed data, and limited field measurements, to investigate the partitioning of flood transmissions losses based on seven flood events between February 2006 and April 2012 along a 180 km reach of the Diamantina River in the Lake Eyre Basin, Australia. Transmission losses were found to be high, on average 46% of total inflow within 180 km reach segment or 7 GL/km (range: 4-10 GL/km). However, in 180 km reach, transmission losses vary non-linearly with flood discharge, with smaller flows resulting in higher losses (up to 68%), which diminish in higher flows (down to 24%) and in general there is a minor increase in losses with distance downstream. Partitioning these total losses into the major components shows that actual evaporation was the most significant component (21.6% of total inflow), followed by infiltration (13.2%) and terminal water storage (11.2%). Lateral inflow can be up to 200% of upstream inflow (mean = 86%) and is therefore a critical parameter in the water balance and transmission loss calculations. This study

  20. Analysis of the effects of human activities on the hydromorphological evolution channel of the Saint-Maurice River downstream from La Gabelle dam (Quebec, Canada)

    Science.gov (United States)

    Vadnais, Marie-Ève; Assani, Ali A.; Landry, Raphaëlle; Leroux, Denis; Gratton, Denis

    2012-11-01

    During the first half of the twentieth century, many hydroelectric facilities were built in the Saint-Maurice River watershed, followed by other human activities in the second half of the century (pleasure boating, boom dismantling, urbanization, etc.). The goal of the study is to constrain the effects of these various types of human activities, particularly those of the many dams in the watershed, on the hydromorphological evolution of the Saint-Maurice River downstream from the La Gabelle (dam) power plant (43,000 km2). Comparison of specific discharge in this river with streamflow measured in a natural river setting reveals a significant decrease in seasonal maximum flows, aside from winter, when daily maximum flows increased significantly. Also, unlike natural rivers, the long-term trend in spring flows is not characterized by a significant change in mean downstream from the La Gabelle plant. These hydrological changes are linked to the inversion-type management mode of the reservoirs built downstream from the plant. As for the morphological evolution, the longitudinal variability of bankfull width downstream from the plant shows two significant shifts in mean: the first, which was quasi-abrupt, took place downstream of the des Forges rapid; and the second, which was gradual, occurred upstream from the confluence of the Saint-Maurice River with the St. Lawrence River, above the point where the Saint-Maurice splits into two branches. Comparison of aerial photographs taken at various times (1948, 1964, 1975, 1996, and 2008) reveals no significant change in the mean of bankfull width over time. However, a significant increase in the surface area of islets located at the confluence was observed, which is caused by sediment accumulation. These sediments were likely derived from local bank erosion resulting from anthropogenic changes.

  1. Navigation Channels, Port of Green Bay (Bay of Green Bay & Fox River), Published in 2008, 1:12000 (1in=1000ft) scale, Brown County, WI.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Navigation Channels dataset, published at 1:12000 (1in=1000ft) scale, was produced all or in part from Hardcopy Maps information as of 2008. It is described as...

  2. Research on two-bank training strategy for wandering channels of Lower Yellow River%再论黄河下游游荡性河道双向整治方案

    Institute of Scientific and Technical Information of China (English)

    齐璞; 孙赞盈; 齐宏海

    2011-01-01

    从小浪底水库运用后河道整治面临的新问题:研究了宽河固堤(微弯整治)、窄河固堤与双岸整治形成的特定的历史背景,其整治目的与要求有所不同.微弯整治是在防洪抢险整治基础上演变的,使河道的游荡范围有所减小,防洪安全性有所提高.但微弯整治在下游游荡性河道极为宽浅,多条流路中选择一条典型流路作为规划治导线,通过人工造弯,试图形成人工控制的弯曲性河流,具有一定的盲目性;窄河固堤的思想是在新的历史条件下,从社会发展,经济效益等多方面分析后提出的;双向整治是基于对黄河窄深河道泄洪输沙能力、过洪机理,淤滩刷槽之间没有联系的认识基础上提出的.小浪底水库泥沙多年调节,优化了来水来沙条件,通过黄河实测资料分析与动床模型试验证明双向整治对游荡河道治理有效,是形成窄深河槽,稳定主槽,保证防洪安全与提高河道的输沙能力所必须.为充分利用洪水,长距离输沙入海,实现下游主槽不淤高的目标提供了可能.%Facing the new fiver training problems after the commissioning of Xiaolangdi Project, this paper analyzes the specific historical backgrounds, different objectives and requirements of three river training strategies, i. e. , the strategy of wide channel to secure the banks ( minor curvature treatment), the strategy of narrowing the channel to secure the banks, and the strategy of two-bank training. The minor curvature treatment strategy has been evolved from the flood protection and emergency management, and it reduces the wandering range to a certain extent and increases the flood protection security. But the wandering channel becomes very shallow and wide, and the channel realignment plan will only be determined by picking one flow path among multiple flow paths. By implementing man-made curvatures, an unnatural curved channel will be developed, so this strategy should be considered

  3. Alkylphenols and alkylphenol ethoxylates, PBDEs, PCBs and chlorinated pesticides in largemouth bass from North Shore Channel of the Chicago River, Illinois

    Science.gov (United States)

    Fall 2006 and Spring 2007 samples of fish, water and effluent (Chicago Northside Water Reclamation Plant) were collected and analyzed for several persistent and semi-persistent chemicals that are believed to be significantly loading into the North Branch of the Chicago River from the Northside Water...

  4. Prehistoric Cultural Resources within the Right-of-Way of the Proposed Little Blue River Channel, Jackson County, Missouri. Part 1.

    Science.gov (United States)

    1985-01-01

    only occur in the upland prairie near the headwaters of the Little Blue River (McCourt 1917:52-53). Argentine Limestone Js the uppermost member of...producing a tri- angluar or lanceolate form with a well defined working edge and hafting element. Stems, side, corner or basal notches are present. These

  5. Modelling extraordinary floods and sedimentological processes in a large channel-floodplain system of the Lower Paraná River (Argentina)

    Institute of Scientific and Technical Information of China (English)

    Marina L. Garcia; Pedro A. Basile; Gerardo A. Riccardi; José F. Rodriguez

    2015-01-01

    abstract A quasi-2D unsteady flow and sediment transport model suitable for the simulation of large lowland river systems, including their floodplains, is presented. The water flow and sediment equations are discretised using an interconnected irregular cells scheme, in which different simplifications of the 1D de Saint Venant equations are used to define the discharge laws between cells. Spatially-distributed transport and deposition of fine sediments throughout the river-floodplain system are simulated. The model is applied over a 208-km reach of the Paraná River between the cities of Diamante and Ramallo (Argentina) comprising a river-floodplain area of 8100 km². After calibration and validation, the model is applied to predict water and sediment dynamics during synthetically generated extraordinary floods of 100, 1000, and 10,000 years return period. The potential impact of a 56-km long road embankment constructed across the entire floodplain is simulated and compared to model results without the embankment. The embankment results in increases in upstream water levels, inundation extent, flow duration, and sediment deposition.

  6. Technical Note: Automatic river network generation for a physically-based river catchment model

    OpenAIRE

    2010-01-01

    SHETRAN is a physically-based distributed modelling system that gives detailed simulations in time and space of water flow and sediment and solute transport in river catchments. Standard algorithms for the automatic generation of river channel networks from digital elevation data are impossible to apply in SHETRAN and other similar models because the river channels are assumed to run along the edges of grid cells. In this work a new algorithm for the automatic generation of a river cha...

  7. 18 CFR 1304.303 - Channel excavation.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Channel excavation... OF CONSTRUCTION IN THE TENNESSEE RIVER SYSTEM AND REGULATION OF STRUCTURES AND OTHER ALTERATIONS Activities on TVA Flowage Easement Shoreland § 1304.303 Channel excavation. (a) Channel excavation of...

  8. Channel Classification across Arid West Landscapes in Support of OHW Delineation

    Science.gov (United States)

    2013-01-01

    perspective at Agua Fria River, AZ ...................................................................... 24 Figure 12. Landscape perspective at...27 Figure 16. Active channel at Agua Fria River, AZ...33 Figure 24. Landscape perspective at Agua Fria River, AZ

  9. The ecological impact of tidal pond channelization on the distribution of tilapia species (Perciformes: Cichlidae on Buguma creek, Rivers State, Nigeria

    Directory of Open Access Journals (Sweden)

    Blessing Julius Oribhabor

    2011-12-01

    Full Text Available A study of the tilapia species (Perciformes: Cichlidae of a tidal creek in the Southeast of theNiger Delta, Nigeria was conducted to assess the ecological impact of tidal pond channelization. Therewas no significant difference (p>0.05 in the values of the physical and chemical parameters, except fortransparency, water level and salinity (pSarotherodon melanotheron and Tilapia guineensis were recorded during the studies, with S. melanotheron being the dominant species.Orthogonal comparison using Duncan’s Multiple Range test showed that S. melanotheron was the causeof the observed difference in the tilapia population. Although there was positive correlation betweensalinity and the tilapia species at all stations, there was no significant correlation between tilapia speciesand the environmental variables. The findings of this study showed that channelized water bodies havelower qualify fish assemblage when compared to natural water bodies due to a loss of heterogeneoushabitat. Although channelization is inevitable in the development of brackishwater fish ponds,amelioration measures of its adverse effects deserve high priority. However since no significantdifference (p>0.05 existed in the distribution of T. guineensis, this study indicated that not all speciesare impacted by tidal pond channelization.

  10. A COUPLED 1-D AND 2-D CHANNEL NETWORK MATHEMATICAL MODEL USED FOR FLOW CALCULATIONS IN THE MIDDLE REACHES OF THE YANGTZE RIVER

    Institute of Scientific and Technical Information of China (English)

    HAN Dong; FANG Hong-wei; BAI Jing; HE Guo-jian

    2011-01-01

    A coupled one-dimensional(1-D)and two-dimensional(2-D)channel network mathematical model is proposed for flow calculations at nodes in a channel network system in this article.For the 1-D model,the finite difference method is used to discretize the Saint-Venant equations in all channels of a looped network.The Alternating Direction Implicit(ADI)method is adopted for the 2-D model at the nodes.In the coupled model,the 1-D model provides a good approximation with small computational effort,while the 2-D model is applied for complex topography to achieve a high accuracy.An Artificial Neural Network(ANN)method is used for the data exchange and the connectivity between the 1-D and 2-D models.The coupled model is applied to the Jingjiang-Dongting Lake region,to simulate the tremendous looped channel network system,and the results are compared with field data.The good agreement shows that the coupled hydraulic model is more effective than the conventional 1-D model.

  11. Sediment tracing from small torrential channels to gravel-bed rivers using pit tags method. A case study from the upper Guil catchment.

    Science.gov (United States)

    Graff, Kévin; Viel, Vincent; Carlier, Benoit; Lissak, Candide; Arnaud-Fassetta, Gilles; Fort, Monique; Madelin, Malika

    2016-04-01

    In mountainous areas, especially in large catchments with torrential tributaries, the production and sediment transport significantly increase flood impacts in the valley bottoms. The quantification and characterisation of sedimentary transfers are therefore major challenges to provide better flood risk management. As a part of SAMCO (ANR 12 SENV-0004 SAMCO) project, for mountain hazard assessment in a context of global changes, we tried to improve the knowledge of these hydromorphological systems at both spatial and temporal scales, by identifying sediment supply and sediment dynamics from torrential tributaries to the main channel. A sediment budget was used as a tool for quantifying erosion, transport and deposition processes. This research is focused on the upper Guil catchment (Queyras, Southern French Alps - 317 km2) entrenched in "schistes lustrés" and ophiolitic bedrock. This catchment is prone to catastrophic summer floods [June 1957 (>R.I. 100 yr), June 2000 (R.I. 30 yr)] characterised by huge sediment transport from tributaries to downvalley, very much facilitated by strong hillslope-channel connectivity (about 12,000 m3 volume of sediment aggraded in the Peyronnelle fan during the June 2000 RI-30 year flood event). We intend to highlight sediment dynamics on small torrential channels and its connection with gravel-bed streams. Four study sites characterised by avalanche and debris flow-dominated channels located in the upper Guil catchment were investigated. In order to better assess sediment movement, we used the pit-tags technique. In total, 560 pit-tags (pt) have been implemented in four catchments: Peyronnelle (320pt), Combe Morel (40pt), Bouchouse (120pt), and Maloqueste (80pt). Distances and trajectories of gravels sediments have been monitored since two years during summer periods. We specifically describe results obtained along the Peyronnelle channel affected by a large debris-flow during august 2015. Data are used to discuss lag time

  12. Use of complex hydraulic variables to predict the distribution and density of unionids in a side channel of the Upper Mississippi River

    Science.gov (United States)

    Steuer, J.J.; Newton, T.J.; Zigler, S.J.

    2008-01-01

    Previous attempts to predict the importance of abiotic and biotic factors to unionids in large rivers have been largely unsuccessful. Many simple physical habitat descriptors (e.g., current velocity, substrate particle size, and water depth) have limited ability to predict unionid density. However, more recent studies have found that complex hydraulic variables (e.g., shear velocity, boundary shear stress, and Reynolds number) may be more useful predictors of unionid density. We performed a retrospective analysis with unionid density, current velocity, and substrate particle size data from 1987 to 1988 in a 6-km reach of the Upper Mississippi River near Prairie du Chien, Wisconsin. We used these data to model simple and complex hydraulic variables under low and high flow conditions. We then used classification and regression tree analysis to examine the relationships between hydraulic variables and unionid density. We found that boundary Reynolds number, Froude number, boundary shear stress, and grain size were the best predictors of density. Models with complex hydraulic variables were a substantial improvement over previously published discriminant models and correctly classified 65-88% of the observations for the total mussel fauna and six species. These data suggest that unionid beds may be constrained by threshold limits at both ends of the flow regime. Under low flow, mussels may require a minimum hydraulic variable (Rez.ast;, Fr) to transport nutrients, oxygen, and waste products. Under high flow, areas with relatively low boundary shear stress may provide a hydraulic refuge for mussels. Data on hydraulic preferences and identification of other conditions that constitute unionid habitat are needed to help restore and enhance habitats for unionids in rivers. ?? 2008 Springer Science+Business Media B.V.

  13. Littoral steering of deltaic channels

    Science.gov (United States)

    Nienhuis, Jaap H.; Ashton, Andrew D.; Giosan, Liviu

    2016-11-01

    The typically single-threaded channels on wave-influenced deltas show striking differences in their orientations, with some channels oriented into the incoming waves (e.g., Ombrone, Krishna), and others oriented away from the waves (e.g., Godavari, Sao Francisco). Understanding the controls on channel orientation is important as the channel location greatly influences deltaic morphology and sedimentology, both subaerially and subaqueously. Here, we explore channel orientation and consequent feedbacks with local shoreline dynamics using a plan-form numerical model of delta evolution. The model treats fluvial sediment delivery to a wave-dominated coast in two ways: 1) channels are assumed to prograde in a direction perpendicular to the local shoreline orientation and 2) a controlled fraction of littoral sediment transport can bypass the river mouth. Model results suggest that channels migrate downdrift when there is a significant net littoral transport and alongshore transport bypassing of the river mouth is limited. In contrast, river channels tend to orient themselves into the waves when fluvial sediment flux is relatively large, causing the shoreline of the downdrift delta flank to attain the orientation of maximum potential sediment transport for the incoming wave climate. Using model results, we develop a framework to estimate channel orientations for wave-influenced deltas that shows good agreement with natural examples. An increase in fluvial sediment input can cause a channel to reorient itself into incoming waves, behavior observed, for example, in the Ombrone delta in Italy. Our results can inform paleoclimate studies by linking channel orientation to fluvial sediment flux and wave energy. In particular, our approach provides a means to quantify past wave directions, which are notoriously difficult to constrain.

  14. Comparison of the uptake of dioxin-like compounds by caged channel catfish and semipermeable membrane devices in the Saginaw River, Michigan

    Science.gov (United States)

    Gale, Robert W.; Huckins, James N.; Petty, Jimmie D.; Peterman, Paul H.; Williams, Lisa L.; Morse, Douglas; Schwartz, Ted R.; Tillitt, Donald E.

    1996-01-01

    Elevated concentrations of planar, halogenated hydrocarbons have been linked to reproductive problems in a variety of fish-eating birds and mammals in the Great Lakes and in particular Saginaw Bay. Currently, there are no accurate procedures to assess bioavailability of these contaminants. Polychlorinated dibenzo-p-dioxins and dibenzofurans and mono- and non-ortho-chloro-substituted biphenyls in water at the femtogram to picogram per liter range were passively concentrated in semipermeable membrane devices (SPMDs), and these data were compared to the bioconcentration in co-exposed (caged) channel catfish. Sediment-derived water concentration estimates, calculated from a steady-state partitioning model, did not correlate well to those derived from either fish or SPMDs. The use of SPMDs demonstrated the utility of in-situ passive sampling over inference of water concentrations from accumulation in biota or partitioning with sediment. Residues ac cumulated by SPMDs have been shown to be proportional to analyte water concentration, whereas this does not appear to be the case for fish tissues. The greater amounts of 3,3‘,4,4‘-tetrachlorobiphenyl and 2,3,7,8-tetrachlorodibenzofuran accumulated in SPMDs than in exposed channel catfish indicated those non-passive aspects of bioconcentration in organisms, such as biotransformation and elimination, introduced 50−500% error in the assumed degree of exposure.

  15. 长江河口南港采砂对河床稳定性的影响%The Effect of Sand Digging to Bedfrom Stability of the Nangang Channel in the Changjiang River Mouth

    Institute of Scientific and Technical Information of China (English)

    李茂田; 程和琴; 周丰年; 吴敬文; 李伯昌

    2011-01-01

    利用多波束测深及数字高程模型技术发现:南港主槽有若干长50~100m,深3~5m的采砂坑;瑞丰沙体南侧存在高0.5~1.2m,长约1800m的两级陡坎,陡坎下有长1850m、宽400m、体积124.5万立方米的滑坡体.近8年来,瑞丰沙冲刷减少3724万立方米.采砂坑、陡坎与滑坡体形成的主要受采砂及其引起的瑞丰沙顶部水沙通量调整控制,采砂引起瑞丰沙顶部过水断面增加8240m2,涨潮从南小泓分流0.96亿立方米,落潮从南港主槽分流1.43亿立方米.%According to the bed-form data measured by multi-beam echo-sounding system (MBES) and digital elevation model (DEM), this parer is to examine the impacts of pumping-sand on the river bed-form evolution of the Nangang Channel in the Changjiang River mouth. The results is that there were 5 huge sandpits with 50-100m long and 3-5m depth,2 ranges steep ridge with 1800m long and 0.5-1.2m high and 1 huge landslide with 1850m long and 400m wide in Ruifeng shoal edge nearly sandpits in the Nangang Channel ,and the volume of landslide reached 1.245 × 106m3. Furthermore, our data have further demonstrated such bed-from evolutions mainly resulted from human pumping-sand. Reifeng shoal were obviously eroded and the volume decreased 3.724×107m3 recently 8years. It decreased 8240m2 of longitudinal profile area of the middle Ruifeng shoal,and that resulted in water discharge increasing separately 0.966×l08m3 in flood tide and 1.43× 108 m3 in ebb tide.

  16. Technical Note: Automatic river network generation for a physically-based river catchment model

    Directory of Open Access Journals (Sweden)

    S. J. Birkinshaw

    2010-09-01

    Full Text Available SHETRAN is a physically-based distributed modelling system that gives detailed simulations in time and space of water flow and sediment and solute transport in river catchments. Standard algorithms for the automatic generation of river channel networks from digital elevation data are impossible to apply in SHETRAN and other similar models because the river channels are assumed to run along the edges of grid cells. In this work a new algorithm for the automatic generation of a river channel network in SHETRAN is described and its use in an example catchment demonstrated.

  17. Technical Note: Automatic river network generation for a physically-based river catchment model

    Science.gov (United States)

    Birkinshaw, S. J.

    2010-09-01

    SHETRAN is a physically-based distributed modelling system that gives detailed simulations in time and space of water flow and sediment and solute transport in river catchments. Standard algorithms for the automatic generation of river channel networks from digital elevation data are impossible to apply in SHETRAN and other similar models because the river channels are assumed to run along the edges of grid cells. In this work a new algorithm for the automatic generation of a river channel network in SHETRAN is described and its use in an example catchment demonstrated.

  18. Technical Note: Automatic river network generation for a physically-based river catchment model

    Directory of Open Access Journals (Sweden)

    S. J. Birkinshaw

    2010-05-01

    Full Text Available SHETRAN is a physically-based distributed modelling system that gives detailed simulations in time and space of water flow and sediment and solute transport in river catchments. Standard algorithms for the automatic generation of river channel networks from digital elevation data are impossible to apply in SHETRAN and other similar models because the river channels are assumed to run along the edges of grid cells. In this work a new algorithm for the automatic generation of a river channel network in SHETRAN is described and its use in an example catchment demonstrated.

  19. 长江南京至浏河口深水航道航行基面及理论基面初步分析%Preliminary study on the navigation datum plane and theoretical datum plane for deep-water channel from Nanjing to Liuhe River estuary of Yangtze River

    Institute of Scientific and Technical Information of China (English)

    夏云峰; 闻云呈; 张世钊; 徐华

    2012-01-01

    With the development of the 12. 5 m deep-water channel of the Yangtze River estuary, the deep water channel extending up to Nanjing is in urgent need. The start-up year of the existing datum of Nanjing downstream is 1970. In the study, the navigation datum upstream of Jiangyin has been adopted, and the theoretical datum downstream of Jiangyin has been used. With the human activities such as river channel regulations and bridge construction and the natural factors such as sea level rise, the tidal wave from Nanjing downstream has been transformed along distance, the existing datum needs to be recalculated and rechecked. In this paper, tide data of different stations along distance has been collected, interpolated, extended and completed by one dimensional mathematical model. Based on these tide level data, we calculated the datum plane of Nanjing downstream by use of integrated cumulative curve method, and compared the difference between existing datum planes and our calculation datum planes. It is shown that the existing datum planes can ensure ship navigation safety, and that the charts, topographic maps and relevant research results based on the existing datum are reliable and applicable.%由于沿江河道治理、航道整治、桥梁建设等人类活动以及海平面上升等因素的影响,南京以下沿程潮波发生变形,现行的基面需要重新计算与复核.通过收集沿程各站潮位资料,并利用一维数学模型对资料进行插补延伸;根据所得的沿程各站潮位资料,采用综合历时曲线法等手段对南京以下基面进行计算,比较现行基面与本次计算基面的差异.研究表明,南京以下现行的基面是可行的,且对船舶的航行是偏安全的,利用现行基面所测量的海图、地形图及研究成果可信有效.

  20. Bifurcation instability and chute cutoff development in meandering gravel-bed rivers

    NARCIS (Netherlands)

    Van Dijk, Wout M.; Schuurman, Filip; Van de Lageweg, Wietse I.; Kleinhans, Maarten G.

    2014-01-01

    Chute cutoffs reduce sinuosity of meandering rivers and potentially cause a transition from a single to a multiple channel river. The channel bifurcation of the main channel and the mouth of the incipient chute channel controls sediment and flow partitioning and development of the chute. Recent chan

  1. Effect Anaylsis of Split Ratio on the Channel Flow Pattern in the Braided River%分汊河道分流比对河道水流流态影响分析

    Institute of Scientific and Technical Information of China (English)

    常宏兴; 芦松; 武亚辉

    2013-01-01

    结合曹继文关于明渠岸边横向取水的水槽试验成果,应用RNG紊流模型,采用两种自由表面处理方法即刚盖假定和VOF法,对分汊河道不同分流比工况下的水流运动进行三维数值模拟。通过数值模拟计算,得出不同表面处理方法下分汊河道不同分流比工况下的流速分布、水流特性等结果,分流比对分流宽度影响较为明显。%This paper referenced the test results Cao ji-wen booked of lateral intake of open channel along the shore, ap-plied RNG turbulence model, used two kinds of free surface treatment which is rigid-lid assumption and VOF method, make the three-dimensional numerical simulation of flow movement of different split ratio in branching river. Through nu-merical simulation, obtained the velocity distribution, flow characteristics under different methods were obtained. The ef-fect of split ratio on distribution width is obvious.

  2. 小型河床式水电站前期工作阶段调保计算探讨%Discussion on regulation guarantee calculation during preparatory stage of small-scale hydropower station in river channel

    Institute of Scientific and Technical Information of China (English)

    熊晓明

    2013-01-01

      通过分析比较公式法和特性线法的各自特点,给出了在小型水电站前期工作阶段用公式法进行调节保证计算的优点。以某电站为例,详细介绍了用Excel编制公式法算稿进行调节保证计算的步骤,计算结果表明在前期工作阶段公式法能够满足设计精度。%Based on analysis and comparison of formula method and characteristic curve method, the author present⁃ed the advantages of making regulation guarantee calculation by formula method during preparatory stage of small-scale hydropower station in river channel. Taking a power station as example, a detailed introduction was made on the calculating process by formula method and Excel, with the results of calculation up to the requirements for design accuracy.

  3. Latent resonance in tidal rivers, with applications to River Elbe

    Science.gov (United States)

    Backhaus, Jan O.

    2015-11-01

    We describe a systematic investigation of resonance in tidal rivers, and of river oscillations influenced by resonance. That is, we explore the grey-zone between absent and fully developed resonance. Data from this study are the results of a one-dimensional numerical channel model applied to a four-dimensional parameter space comprising geometry, i.e. length and depths of rivers, and varying dissipation and forcing. Similarity of real rivers and channels from parameter space is obtained with the help of a 'run-time depth'. We present a model-channel, which reproduces tidal oscillations of River Elbe in Hamburg, Germany with accuracy of a few centimetres. The parameter space contains resonant regions and regions with 'latent resonance'. The latter defines tidal oscillations that are elevated yet not in full but juvenile resonance. Dissipation reduces amplitudes of resonance while creating latent resonance. That is, energy of resonance radiates into areas in parameter space where periods of Eigen-oscillations are well separated from the period of the forcing tide. Increased forcing enhances the re-distribution of resonance in parameter space. The River Elbe is diagnosed as being in a state of anthropogenic latent resonance as a consequence of ongoing deepening by dredging. Deepening the river, in conjunction with the expected sea level rise, will inevitably cause increasing tidal ranges. As a rule of thumb, we found that 1 m deepening would cause 0.5 m increase in tidal range.

  4. River engineering

    NARCIS (Netherlands)

    De Vries, M.

    1993-01-01

    One dimension models - basic eauations, analytical models, numberical models. One dimensional models -suspended load, roughness and resistance of river beds. Solving river problems - tools, flood mitigation, bank protection.

  5. Developing laminar flow in curved rectangular channels

    NARCIS (Netherlands)

    De Vriend, H.J.

    1978-01-01

    As an intermediate step between earlier investigations on fully developed laminar flow in curved channels of shallow rectancular wet cross-section and the mathematical modeling of turbulent flow in river bends, a mathematical model of developing laminar flow in such channels is investigated. The mos

  6. Stability analysis of gravel-bed rivers: comparison between natural rivers and disturbed rivers due to human activities

    OpenAIRE

    Kaless, Gabriel

    2013-01-01

    The present research studies fluvial processes –water and sediment flows – that define the shape of an alluvial channel. The relationship between forms and processes is complex because they are interrelated: the channel shape influences the water flow which drives the sediments movement on the channel bed that modifies the channel form, closing a circle. Although, the objective of the work is a very old question in fluvial studies, to explain the shape of rivers in terms of external controls ...

  7. Changes in channel morphology over human time scales [Chapter 32

    Science.gov (United States)

    John M. Buffington

    2012-01-01

    Rivers are exposed to changing environmental conditions over multiple spatial and temporal scales, with the imposed environmental conditions and response potential of the river modulated to varying degrees by human activity and our exploitation of natural resources. Watershed features that control river morphology include topography (valley slope and channel...

  8. The Zambezi Channel: A new perspective on submarine channel evolution at low latitudes

    Science.gov (United States)

    Wiles, E.; Green, A.; Watkeys, M.; Jokat, W.

    2017-06-01

    Submarine channels are not stand-alone systems. They are long-lived systems modified by imperceptibly slow processes and rapid gravity flows, in some part controlled by hinterland dynamics. The submarine Zambezi Channel, within the Mozambique Channel, receives sediment from the Zambezi River catchment which has a dynamic tectonic and morphological history. Using recently collected multibeam bathymetry and PARASOUND data we discuss the geomorphology of the Zambezi Channel. Results show this system to be distinct in geomorphologic character when compared to other low-latitude submarine channels, sharing similarities with high-latitude systems. We propose a new, source-to-sink, hypothesis for the evolution of the Zambezi Channel, taking in to consideration hinterland tectonics, palaeo-lake development, river capture and rapid gravity flows. This hypothesis accounts for the unique present-day anatomy of the Zambezi Channel within the dynamic framework of the systems regional setting.

  9. Geometric properties of river cross sections and associated hydrodynamic implications in Wuhan-Jiujiang river reach, the Yangtze River%长江中游武汉-九江河段河道形态及水动力学特征

    Institute of Scientific and Technical Information of China (English)

    张强; 施雅风; 熊明

    2009-01-01

    Based on measured hydrological data by using ship-mounted Acoustic Doppler Current Profiler (ADCP) instrument, we analyzed shapes of river cross sections of the middle Yangtze River basin (mainly focusing on Makou and Tianjiazhen river reach). Hydrodynamic properties of river channels were also discussed. The research results indicate that nonlinear relationships can be identified between river-width/river-depth ratio (W/D ratio), sizes of cross section and mean flow velocity. Positive relations are detected between W/D ratio and mean flow velocity when W/D<1; and negative relations are observed when W/D>1. Adverse relationships can be obtained between W/D ratio and cross-section area. Geomorphologic and geologic survey indicates different components of river banks in the wider and narrower river reaches respectively. These may be the main driving factors causing unique hydrological properties of river channels in the middle Yangtze River basin. Narrower river cross sections tend to raise water level in the upstream river reach near narrower river channel, giving rise to backwater effects. River knots can cause serious backwater effects, which is harmful for flood mitigation. However river knots will also stabilize river channel and this will be beneficial for river channel management. The results of this paper may be helpful for flood mitigation and river channel management in the middle Yangtze River basin.

  10. Controls on plan-form evolution of submarine channels

    Science.gov (United States)

    Imran, J.; Mohrig, D. C.

    2014-12-01

    Vertically aggrading sinuous channels constitute a basic building block of modern submarine fans and the greater continental slope. Interpretation of seismically imaged channels reveals a significant diversity in internal architecture, as well as important similarities and differences in the evolution of submarine channels relative to better studied rivers. Many submarine channel cross sections possess a 'gull wing' shape. Successive stacking of such channels demonstrates that systematic bank erosion is not required in order for lateral migration to occur. The lateral shift of such aggrading channels, however, is expected to be much less dynamic than in the case of terrestrial rivers. Recent high-resolution 3D seismic data from offshore Angola and an upstream segment of the Bengal Submarine Fan show intensely meandering channels that experience considerable lateral shifting during periods of active migration within submarine valleys. The cross sections of the actively migrating channels are similar to meandering river channels characterized by an outer cut-bank and inner-bank accretion. In submarine channels, the orientation of the secondary flow can be river-like or river-reverse depending on the channel gradient, cross sectional shape, and the adaptation length of the channel bend. In river channels, a single circulation cell commonly occupies the entire channel relief, redistributing the bed-load sediment across the channel, and influencing the thread of high velocity and thus the plan-form evolution of the channel. In submarine environments, the height of the circulation cell will be significantly smaller than channel relief, thus leading to development of lower relief point bars from bed-load transport. Nevertheless these "underfit" bars may play an important role in plan-form evolution of submarine channels. In rivers and submarine channels, the inclined surface accretion can be constructed via pure bed-load, suspended-load, or a combination of both transport

  11. Geomorphology and River Dynamics of the Lower Copper River, Alaska

    Science.gov (United States)

    Brabets, Timothy P.; Conaway, Jeffrey S.

    2009-01-01

    Located in south-central Alaska, the Copper River drains an area of more than 24,000 square miles. The average annual flow of the river near its mouth is 63,600 cubic feet per second, but is highly variable between winter and summer. In the winter, flow averages approximately 11,700 cubic feet per second, and in the summer, due to snowmelt, rainfall, and glacial melt, flow averages approximately 113,000 cubic feet per second, an order of magnitude higher. About 15 miles upstream of its mouth, the Copper River flows past the face of Childs Glacier and enters a large, broad, delta. The Copper River Highway traverses this flood plain, and in 2008, 11 bridges were located along this section of the highway. The bridges cross several parts of the Copper River and in recent years, the changing course of the river has seriously damaged some of the bridges. Analysis of aerial photography from 1991, 1996, 2002, 2006, and 2007 indicates the eastward migration of a channel of the Copper River that has resulted in damage to the Copper River Highway near Mile 43.5. Migration of another channel in the flood plain has resulted in damage to the approach of Bridge 339. As a verification of channel change, flow measurements were made at bridges along the Copper River Highway in 2005-07. Analysis of the flow measurements indicate that the total flow of the Copper River has shifted from approximately 50 percent passing through the bridges at Mile 27, near the western edge of the flood plain, and 50 percent passing through the bridges at Mile 36-37 to approximately 5 percent passing through the bridges at Mile 27 and 95 percent through the bridges at Mile 36-37 during average flow periods. The U.S. Geological Survey's Multi-Dimensional Surface-Water Modeling System was used to simulate water-surface elevation and velocity, and to compute bed shear stress at two areas where the Copper River is affecting the Copper River Highway. After calibration, the model was used to examine the

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

    Science.gov (United States)

    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.

  13. Hillslope-derived blocks retard river incision

    Science.gov (United States)

    Shobe, Charles M.; Tucker, Gregory E.; Anderson, Robert S.

    2016-05-01

    The most common detachment-limited river incision models ignore the effects of sediment on fluvial erosion, yet steep reaches of mountain rivers often host clusters of large (>1 m) blocks. We argue that this distribution of blocks is a manifestation of an autogenic negative feedback in which fast vertical river incision steepens adjacent hillslopes, which deliver blocks to the channel. Blocks inhibit incision by shielding the bed and enhancing form drag. We explore this feedback with a 1-D channel-reach model in which block delivery by hillslopes depends on the river incision rate. Results indicate that incision-dependent block delivery can explain the block distribution in Boulder Creek, Colorado. The proposed negative feedback may significantly slow knickpoint retreat, channel adjustment, and landscape response compared to rates predicted by current theory. The influence of hillslope-derived blocks may complicate efforts to extract base level histories from river profiles.

  14. Understanding the influence of predation on introduced fishes on juvenile salmonids in the Columbia River Basin: Closing some knowledge gaps. Late summer and fall diet and condition of smallmouth bass, walleye, and channel catfish in the middle Columbia River, USA. Interim Report of Research 2011.

    Science.gov (United States)

    Rose, Brien P.; Hansen, Gabriel S.; Weaver,; Ayers,; Van Dyke, Erick S.; Mesa, Matthew G.

    2012-01-01

    American shad Alosa sapidissima in the middle Columbia River (MCR)—a high energy food available in the summer and fall—may be contributing to the increased growth and enhanced condition of nonnative piscivores. To test this hypothesis we quantified the late summer and autumn diets of smallmouth bass Micropterus dolomieu, walleye Sander vitreus, and channel catfish Ictalurus punctatus in the three lowermost reservoirs on the Columbia River (Bonneville [BON], The Dalles [TDA], and John Day [JDA]). The diet of smallmouth bass (SMB) was fairly similar among reservoirs, with crustaceans (52–82%) and fish (13–38%) being the dominant prey groups by percent mass. Cottidae were usually the dominant fish prey in the diet of SMB at all areas and the contribution of juvenile shad ranged from 0–8.2%. Fish (mostly Cyprinidae and Cottidae) were always the dominant prey item for walleye (WAL) at all areas and at all times, ranging from 70–100% of their diet by mass. Juvenile American shad composed from 10–27% (by mass) of the diet of walleye, depending on area and month. For channel catfish (CHC), the most common prey items consumed were crustaceans (20%–80% by mass) and unidentified items (30%–80%). Fish represented a relatively small component (< 4%) of their diet. We also evaluated the condition of SMB and WAL by determining relative weights (Wr) and hepatosomatic indices (HSI). Mean Wr for SMB greater than 300 mm ranged from 0.89 to 0.94 depending on area and month and showed a significant increase from August to September for fish in BON only. Overall, mean Wr of WAL was similar at all areas, ranging from 0.89–0.91, and increased significantly from September to mid-October and November for fish in TDA only. Overall, mean HSI of SMB ranged from 1.18 to 1.48, did not differ between fish in different reservoirs, and increased significantly from September to mid-October and November for fish from the lower JDA only. Mean HSI of WAL was significantly higher in

  15. Anastomosing rivers: a review of their classification, origin and sedimentary products

    NARCIS (Netherlands)

    Makaske, B.

    2001-01-01

    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 plantform

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

    Science.gov (United States)

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

    2015-12-01

    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.

  17. 78 FR 3836 - Drawbridge Operation Regulation; Shark River, Avon, NJ

    Science.gov (United States)

    2013-01-17

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; Shark River, Avon, NJ AGENCY: Coast... which are across the Shark River (South Channel), at Avon Township, NJ. This deviation is necessary to facilitate machinery replacement on the Shark River railroad bridge. This temporary deviation will allow...

  18. 77 FR 57022 - Drawbridge Operation Regulation; Shark River, Avon, NJ

    Science.gov (United States)

    2012-09-17

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; Shark River, Avon, NJ AGENCY: Coast..., and the S35 bridge, mile 0.9, all of which are across the Shark River (South Channel), at Avon Township, NJ. This deviation is necessary to facilitate stringer replacement on the Shark River...

  19. Variable input parameter influence on river corridor prediction

    NARCIS (Netherlands)

    Zerfu, T.; Beevers, L.; Crosato, A.; Wright, N.

    2015-01-01

    This paper considers the erodible river corridor, which is the area in which the main river channel is free to migrate over a period of time. Due to growing anthropogenic pressure, predicting the corridor width has become increasingly important for the planning of development along rivers. Several a

  20. Modelling of meander migration in an incised channel

    Institute of Scientific and Technical Information of China (English)

    Jianchun HUANG; Blair P GREIMANN; Timothy J RANDLE

    2014-01-01

    An updated linear computer model for meandering rivers with incision has been developed. The model simulates the bed topography, flow field, and bank erosion rate in an incised meandering channel. In a scenario where the upstream sediment load decreases (e.g., after dam closure or soil conservation), alluvial river experiences cross section deepening and slope flattening. The channel migration rate might be affected in two ways:decreased channel slope and steeped bank height. The proposed numerical model combines the traditional one-dimensional (1D) sediment transport model in simulating the channel erosion and the linear model for channel meandering. A non-equilibrium sediment transport model is used to update the channel bed elevation and gradations. A linear meandering model was used to calculate the channel alignment and bank erosion/accretion, which in turn was used by the 1D sediment transport model. In the 1D sediment transport model, the channel bed elevation and gradations are represented in each channel cross section. In the meandering model, the bed elevation and gradations are stored in two dimensional (2D) cells to represent the channel and terrain properties (elevation and gradation). A new method is proposed to exchange information regarding bed elevations and bed material fractions between 1D river geometry and 2D channel and terrain. The ability of the model is demonstrated using the simulation of the laboratory channel migration of Friedkin in which channel incision occurs at the upstream end.

  1. Contested Rivers

    DEFF Research Database (Denmark)

    Gorm Hansen, Louise Lyngfeldt

    explores translocal connections through ethnographic fieldwork at a global water conference and preliminary fieldwork at chosen locations on China's Nu River. The Nu River is one of the last undammed rivers in Asia and runs through China close to the Chinese-Burmese border, then flows into the Andaman Sea...

  2. Mechanosensitive Channels

    Science.gov (United States)

    Martinac, Boris

    Living cells are exposed to a variety of mechanical stimuli acting throughout the biosphere. The range of the stimuli extends from thermal molecular agitation to potentially destructive cell swelling caused by osmotic pressure gradients. Cellular membranes present a major target for these stimuli. To detect mechanical forces acting upon them cell membranes are equipped with mechanosensitive (MS) ion channels. Functioning as molecular mechanoelectrical transducers of mechanical forces into electrical and/or chemical intracellular signals these channels play a critical role in the physiology of mechanotransduction. Studies of prokaryotic MS channels and recent work on MS channels of eukaryotes have significantly increased our understanding of their gating mechanism, physiological functions, and evolutionary origins as well as their role in the pathology of disease.

  3. Nitrogen and phosphorus in the Upper Mississippi River: Transport, processing, and effects on the river ecosystem

    Science.gov (United States)

    Houser, J.N.; Richardson, W.B.

    2010-01-01

    Existing research on nutrients (nitrogen and phosphorus) in the Upper Mississippi River (UMR) can be organized into the following categories: (1) Long-term changes in nutrient concentrations and export, and their causes; (2) Nutrient cycling within the river; (3) Spatial and temporal patterns of river nutrient concentrations; (4) Effects of elevated nutrient concentrations on the river; and (5) Actions to reduce river nutrient concentrations and flux. Nutrient concentration and flux in the Mississippi River have increased substantially over the last century because of changes in land use, climate, hydrology, and river management and engineering. As in other large floodplain rivers, rates of processes that cycle nitrogen and phosphorus in the UMR exhibit pronounced spatial and temporal heterogeneity because of the complex morphology of the river. This spatial variability in nutrient processing creates clear spatial patterns in nutrient concentrations. For example, nitrate concentrations generally are much lower in off-channel areas than in the main channel. The specifics of in-river nutrient cycling and the effects of high rates of nutrient input on UMR have been less studied than the factors affecting nutrient input to the river and transport to the Gulf of Mexico, and important questions concerning nutrient cycling in the UMR remain. Eutrophication and resulting changes in river productivity have only recently been investigated the UMR. These recent studies indicate that the high nutrient concentrations in the river may affect community composition of aquatic vegetation (e. g., the abundance of filamentous algae and duckweeds), dissolved oxygen concentrations in off-channel areas, and the abundance of cyanobacteria. Actions to reduce nutrient input to the river include changes in land-use practices, wetland restoration, and hydrological modifications to the river. Evidence suggests that most of the above methods can contribute to reducing nutrient concentration in

  4. Erosion, sediment transportation and accumulation in rivers

    Institute of Scientific and Technical Information of China (English)

    N.I.ALEKSEEVSKIY; K.M.BERKOVICH; R.S.CHALOV

    2008-01-01

    The present paper analyses the interrelation between erosion,sediment transportation and accumulation proposed by N.I.Makkaveyev (1908-1983) and its further development in modem studies of river channel processes in Russia.Spatio-temporal linkages between erosion and accumulation are defined considering channel processes at different scales - river longitudinal profile,channel morphological patterns,alluvial bedforms (bars,dunes) and individual sediment particles.Relations between river geomorphic activity,flow transportation capacity and sediment budgets are established (sediment input and output;channel bed erosion and sediment entrainment into flow -termination of sediment transport and its deposition).Channel planforms,floodplain segments separated by the latter and alluvial channel bedforms are shown to be geomorphic expressions of sediment transport process at different spatial and temporal scales.This paper is dedicated to the 100th anniversary of N.I.Makkaveyev,Professor of the Moscow State University,author of the book "River channel and erosion in its basin" (1955).That book is regarded in Russia as the pioneering work which initiated the complex hydrological and geographical studies of channel processes and laid a basis for the theory of unified fluvial erosion-accumulation process.

  5. High resolution channel geometry from repeat aerial imagery

    Science.gov (United States)

    King, T.; Neilson, B. T.; Jensen, A.; Torres-Rua, A. F.; Winkelaar, M.; Rasmussen, M. T.

    2015-12-01

    River channel cross sectional geometry is a key attribute for controlling the river energy balances where surface heat fluxes dominate and discharge varies significantly over short time periods throughout the open water season. These dynamics are seen in higher gradient portions of Arctic rivers where surface heat fluxes can dominates river energy balances and low hillslope storage produce rapidly varying hydrographs. Additionally, arctic river geometry can be highly dynamic in the face of thermal erosion of permafrost landscape. While direct in-situ measurements of channel cross sectional geometry are accurate, they are limited in spatial resolution and coverage, and can be access limited in remote areas. Remote sensing can help gather data at high spatial resolutions and large areas, however techniques for extracting channel geometry is often limited to the banks and flood plains adjacent to river, as the water column inhibits sensing of the river bed itself. Green light LiDAR can be used to map bathymetry, however this is expensive, difficult to obtain at large spatial scales, and dependent on water quality. Alternatively, 3D photogrammetry from aerial imagery can be used to analyze the non-wetted portion of the river channel, but extracting full cross sections requires extrapolation into the wetted portion of the river. To bridge these gaps, an approach for using repeat aerial imagery surveys with visual (RGB) and near infrared (NIR) to extract high resolution channel geometry for the Kuparuk River in the Alaskan Arctic was developed. Aerial imagery surveys were conducted under multiple flow conditions and water surface geometry (elevation and width) were extracted through photogrammetry. Channel geometry was extracted by combining water surface widths and elevations from multiple flights. The accuracy of these results were compared against field surveyed cross sections at many locations throughout the study reach and a digital elevation model created under

  6. Straight river: its formation and speciality

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Straight river is generally regarded as one of the typical river patterns in conventional classifications in terms of their channel plain landforms. However, very few straight patterns were found to be distributed in wider spatial and temporal spans in the self-adjusted fluvial rivers. Thus, the questions occur such as that is it possible for a channel takes on a stable straight pattern? What are the main factors controlling the processes of the river pattern formation and transformation from a straight to other patterns? Various theories and hypotheses including geomorphic threshold hypothesis, the extreme hypothesis on energy dissipation rate, the stability theory, etc. have been developed to explain the aforementioned questions, but none of them is sound for the explanation to the straight-river formation. From the modern fluvial plain patterns, the straight patterns are not as stable as other typical patterns which occurred in nature; from the historic records of the river sedimentation, no apparent evidence was found to support the stable straight river evolution. Based on the analysis of existing theories, observations, evolvement processes of the channel patterns in the experimental results, this paper concluded that the straight pattern should not be included as one of the typical patterns that are self-formed and developed. This study is of importance to understanding of the river pattern formation and transformation.

  7. The science and practice of river restoration

    Science.gov (United States)

    Wohl, Ellen; Lane, Stuart N.; Wilcox, Andrew C.

    2015-08-01

    River restoration is one of the most prominent areas of applied water-resources science. From an initial focus on enhancing fish habitat or river appearance, primarily through structural modification of channel form, restoration has expanded to incorporate a wide variety of management activities designed to enhance river process and form. Restoration is conducted on headwater streams, large lowland rivers, and entire river networks in urban, agricultural, and less intensively human-altered environments. We critically examine how contemporary practitioners approach river restoration and challenges for implementing restoration, which include clearly identified objectives, holistic understanding of rivers as ecosystems, and the role of restoration as a social process. We also examine challenges for scientific understanding in river restoration. These include: how physical complexity supports biogeochemical function, stream metabolism, and stream ecosystem productivity; characterizing response curves of different river components; understanding sediment dynamics; and increasing appreciation of the importance of incorporating climate change considerations and resiliency into restoration planning. Finally, we examine changes in river restoration within the past decade, such as increasing use of stream mitigation banking; development of new tools and technologies; different types of process-based restoration; growing recognition of the importance of biological-physical feedbacks in rivers; increasing expectations of water quality improvements from restoration; and more effective communication between practitioners and river scientists.

  8. Parameter estimation in channel network flow simulation

    Institute of Scientific and Technical Information of China (English)

    Han Longxi

    2008-01-01

    Simulations of water flow in channel networks require estimated values of roughness for all the individual channel segments that make up a network. When the number of individual channel segments is large, the parameter calibration workload is substantial and a high level of uncertainty in estimated roughness cannot be avoided. In this study, all the individual channel segments are graded according to the factors determining the value of roughness. It is assumed that channel segments with the same grade have the same value of roughness. Based on observed hydrological data, an optimal model for roughness estimation is built. The procedure of solving the optimal problem using the optimal model is described. In a test of its efficacy, this estimation method was applied successfully in the simulation of tidal water flow in a large complicated channel network in the lower reach of the Yangtze River in China.

  9. How integrated is river basin management?

    Science.gov (United States)

    Downs, Peter W.; Gregory, Kenneth J.; Brookes, Andrew

    1991-05-01

    Land and water management is increasingly focused upon the drainage basin. Thirty-six terms recently used for schemes of “integrated basin management” include reference to the subject or area and to the aims of integrated river basin management, often without allusion to the multiobjective nature. Diversity in usage of terms has occurred because of the involvement of different disciplines, of the increasing coherence of the drainage basin approach, and the problems posed in particular parts of the world. The components included in 21 different approaches are analyzed, and, in addition to showing that components related broadly to water supply, river channel, land, and leisure aspects, it is concluded that there are essentially five interrelated facets of integrated basin management that involved water, channel, land, ecology, and human activity. Two aspects not fully included in many previous schemes concern river channel changes and the dynamic integrity of the fluvial system. To clarify the terminology used, it is suggested that the term comprehensive river basin management should be used where a wide range of components is involved, whereas integrated basin management can signify the interactions of components and the dominance of certain components in the particular area. Holistic river basin management is advocated as a term representing an approach that is both fully comprehensive and integrated but also embraces the energetics of the river system and consideration of changes of river channels and of human impacts throughout the river system. The paradigm of working with the river can be extended to one of working with the river in the holistic basin context.

  10. Constructing river stage-discharge rating curves using remotely sensed river cross-sectional inundation areas and river bathymetry

    Science.gov (United States)

    Pan, Feifei; Wang, Cheng; Xi, Xiaohuan

    2016-09-01

    Remote sensing from satellites and airborne platforms provides valuable data for monitoring and gauging river discharge. One effective approach first estimates river stage from satellite-measured inundation area based on the inundation area-river stage relationship (IARSR), and then the estimated river stage is used to compute river discharge based on the stage-discharge rating (SDR) curve. However, this approach is difficult to implement because of a lack of data for constructing the SDR curves. This study proposes a new method to construct the SDR curves using remotely sensed river cross-sectional inundation areas and river bathymetry. The proposed method was tested over a river reach between two USGS gauging stations, i.e., Kingston Mines (KM) and Copperas Creek (CC) along the Illinois River. First a polygon over each of two cross sections was defined. A complete IARSR curve was constructed inside each polygon using digital elevation model (DEM) and river bathymetric data. The constructed IARSR curves were then used to estimate 47 river water surface elevations at each cross section based on 47 river inundation areas estimated from Landsat TM images collected during 1994-2002. The estimated water surface elevations were substituted into an objective function formed by the Bernoulli equation of gradually varied open channel flow. A nonlinear global optimization scheme was applied to solve the Manning's coefficient through minimizing the objective function value. Finally the SDR curve was constructed at the KM site using the solved Manning's coefficient, channel cross sectional geometry and the Manning's equation, and employed to estimate river discharges. The root mean square error (RMSE) in the estimated river discharges against the USGS measured river discharges is 112.4 m3/s. To consider the variation of the Manning's coefficient in the vertical direction, this study also suggested a power-law function to describe the vertical decline of the Manning

  11. Positron Channeling

    CERN Document Server

    Badikyan, Karen

    2016-01-01

    The possibility of channeling the low-energy relativistic positrons around separate crystallographic axes with coaxial symmetry of negative ions in some types of crystals is shown. The process of annihilation of positrons with electrons of medium was studied in detail.

  12. Brands & Channels

    Institute of Scientific and Technical Information of China (English)

    Alice Yang

    2009-01-01

    @@ "Brands" and "Channels" are the two most important things in Ku-Hai Chen's eyes when doing business with Main-land China. Ku-Hai Chen, Executive Director of the International Trade Institute of Taiwan External Trade Development Council (TAITRA), flies frequently between Chinese Taipei and Mainland China, and was in Beijing earlier this month for his seminar.

  13. River nomads

    DEFF Research Database (Denmark)

    2016-01-01

    River nomads is a movie about people on the move. The documentary film explores the lifestyle of a group of nomadic fishermen whose mobility has been the recipe of success and troubles. Engaged in trade and travel, twice a year the river nomads form impressive convoys of majestic pirogues and set...... and liberated lifestyle and the breath-taking landscapes and vistas offered by the Niger River. River Nomads is also a personal account of the Kebbawa’s way of life and their current struggles as nomadic folk living in a world divided by borders and ruled by bureaucrats....

  14. 长江下游南通至南京段深水航道设计通航标准研究%Designed navigational standards for deepwater channel in the lower stretch of the Changjiang River between Nantong and Nanjing

    Institute of Scientific and Technical Information of China (English)

    徐元; 黄志扬

    2014-01-01

    As ports and harbours have been developing rapidly and riverside industrial zones booming in recent years alongside the Changjiang River in Jiangsu province, it is urgent to improve the existing navigable channels’ ability to handle traffic and adopt severer standards for navigable waterways in the lower stretch of the Changjiang River downstream of Nanjing. The lower stretch of the river downstream of Nanjing could be divided into two parts at the place where Jiangyin bridge locates. This paper demonstrates appropriate design vessel-types for navigation, designed navigational standards and desired geometry and dimensions of channels along the river in connection with physical conditions and engineering restrictions, demands of ports and local economic development and the sailing requirements of larger ships. It proposes the principle on value-taking for desired geometry and dimensions of deepwater channels and further gives recommended values in the main sections. Based on the spatial and temporal changes in hydrographic conditions in the studied river stretch, the paper gives the limited drafts for design vessel-types with different allowable under-keel clearance at different water level guarantee rates, and shows that the seasonal changes in draft limitation of large-scaled vessels should be taken into account in ship operations.%随着江苏沿江港口发展和沿江经济产业带布局的实施,长江南京以下河段航道的能力提升和标准提高已成迫切需要。根据工程河段沿程自然条件与工程限制条件、港口与地方经济需求和船舶大型化要求,分区段论证了适合的通航设计船型、设计通航标准和航道建设规模,提出深水航道的尺度取值原则并给出主要区段的推荐取值。基于工程河段水文条件的时空变化特点,给出各设计船型不同水位保证率的限制吃水,并认为通航管理中应充分考虑大型船舶限制吃水的季节变化。

  15. 33 CFR 162.205 - Suisun Bay, San Joaquin River, Sacramento River, and connecting waters, CA.

    Science.gov (United States)

    2010-07-01

    .... (a) San Joaquin River Deep Water Channel between Suisun Bay and the easterly end of the channel at... Suisun Bay and easterly end of Turning Basin at West Sacramento; use, administration, and navigation—(1... North End Light at latitude 38°06′16″ N., longitude 121°42′32.5″ W.; thence easterly to latitude...

  16. Evaluating competing hypotheses for the origin and dynamics of river anastomosis

    NARCIS (Netherlands)

    Kleinhans, M.G.; Haas, de T.; Lavooi, E.; Makaske, B.

    2012-01-01

    Anastomosing rivers have multiple interconnected channels that enclose flood basins. Various theories potentially explain this pattern, including an increased discharge conveyance and sediment transport capacity of multiple channels, deltaic branching, avulsion forced by base-level rise, or a tenden

  17. 下荆江人工裁弯30年%River Cutoff Practices on Lower Jingjiang Section of Changjiang River in the Last 30 Years

    Institute of Scientific and Technical Information of China (English)

    潘庆燊

    2002-01-01

    River cutoff works have been implemented on Lower Jingjiang section for 30 years. Engineering practices have shown that channel straightening has been the river regulation measure for the permanent control of the meandering Lower Jingjiang section. River cutoff have been carried out in accordance with the evolution property of meandering rivers and these works have brought about expected benefits. It has also been noted that certain aspects in river cutoff had not been fully understood. River cutoff is a dynamic engineering. River channel evolution properties shall be fully understood so as to adroitly guide actions according to circumstances in cutoff works. In addition, river channel evolution observation and engineering effectiveness monitoring should be strengthened with a view to update the designs. The diversion canals for channel shortening are of great importance that will account for the success or failure of river cutoff works. The newly formed river channels and the river regime control works on the adjacent upper and lower reaches are guarantees for river cutoff works to be brought into play in the long run.

  18. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key compon

  19. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

  20. Valley evolution by meandering rivers

    Science.gov (United States)

    Limaye, Ajay Brian Sanjay

    Fluvial systems form landscapes and sedimentary deposits with a rich hierarchy of structures that extend from grain- to valley scale. Large-scale pattern formation in fluvial systems is commonly attributed to forcing by external factors, including climate change, tectonic uplift, and sea-level change. Yet over geologic timescales, rivers may also develop large-scale erosional and depositional patterns that do not bear on environmental history. This dissertation uses a combination of numerical modeling and topographic analysis to identify and quantify patterns in river valleys that form as a consequence of river meandering alone, under constant external forcing. Chapter 2 identifies a numerical artifact in existing, grid-based models that represent the co-evolution of river channel migration and bank strength over geologic timescales. A new, vector-based technique for bank-material tracking is shown to improve predictions for the evolution of meander belts, floodplains, sedimentary deposits formed by aggrading channels, and bedrock river valleys, particularly when spatial contrasts in bank strength are strong. Chapters 3 and 4 apply this numerical technique to establishing valley topography formed by a vertically incising, meandering river subject to constant external forcing---which should serve as the null hypothesis for valley evolution. In Chapter 3, this scenario is shown to explain a variety of common bedrock river valley types and smaller-scale features within them---including entrenched channels, long-wavelength, arcuate scars in valley walls, and bedrock-cored river terraces. Chapter 4 describes the age and geometric statistics of river terraces formed by meandering with constant external forcing, and compares them to terraces in natural river valleys. The frequency of intrinsic terrace formation by meandering is shown to reflect a characteristic relief-generation timescale, and terrace length is identified as a key criterion for distinguishing these

  1. Assessing geomorphic sensitivity in relation to river capacity for adjustment

    Science.gov (United States)

    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

  2. River history and tectonics.

    Science.gov (United States)

    Vita-Finzi, C

    2012-05-13

    The analysis of crustal deformation by tectonic processes has gained much from the clues offered by drainage geometry and river behaviour, while the interpretation of channel patterns and sequences benefits from information on Earth movements before or during their development. The interplay between the two strands operates at many scales: themes which have already benefited from it include the possible role of mantle plumes in the breakup of Gondwana, the Cenozoic development of drainage systems in Africa and Australia, Himalayan uplift in response to erosion, alternating episodes of uplift and subsidence in the Mississippi delta, buckling of the Indian lithospheric plate, and changes in stream pattern and sinuosity along individual alluvial channels subject to localized deformation. Developments in remote sensing, isotopic dating and numerical modelling are starting to yield quantitative analyses of such effects, to the benefit of geodymamics as well as fluvial hydrology.

  3. MACROSCOPIC RIVERS

    NARCIS (Netherlands)

    VANDENBERG, IP

    1991-01-01

    We present a mathematical model for the ''river-phenomenon'': striking concentrations of trajectories of ordinary differential equations. This model of ''macroscopic rivers'' is formulated within nonstandard analysis, and stated in terms of macroscopes and singular perturbations. For a subclass, the

  4. The Upper Mississippi River System—Topobathy

    Science.gov (United States)

    Stone, Jayme M.; Hanson, Jenny L.; Sattler, Stephanie R.

    2017-03-23

    The Upper Mississippi River System (UMRS), the navigable part of the Upper Mississippi and Illinois Rivers, is a diverse ecosystem that contains river channels, tributaries, shallow-water wetlands, backwater lakes, and flood-plain forests. Approximately 10,000 years of geologic and hydrographic history exist within the UMRS. Because it maintains crucial wildlife and fish habitats, the dynamic ecosystems of the Upper Mississippi River Basin and its tributaries are contingent on the adjacent flood plains and water-level fluctuations of the Mississippi River. Separate data for flood-plain elevation (lidar) and riverbed elevation (bathymetry) were collected on the UMRS by the U.S. Army Corps of Engineers’ (USACE) Upper Mississippi River Restoration (UMRR) Program. Using the two elevation datasets, the U.S. Geological Survey (USGS) Upper Midwest Environmental Sciences Center (UMESC) developed a systemic topobathy dataset.

  5. Nonlinear channelizer

    Science.gov (United States)

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  6. River-Based Experiential Learning: the Bear River Fellows Program

    Science.gov (United States)

    Rosenberg, D. E.; Shirley, B.; Roark, M. F.

    2012-12-01

    The Department of Civil and Environmental Engineering, Outdoor Recreation, and Parks and Recreation programs at Utah State University (USU) have partnered to offer a new, unique river-based experiential learning opportunity for undergraduates called the Bear River Fellows Program. The program allows incoming freshmen Fellows to experience a river first hand during a 5-day/4-night river trip on the nearby Bear River two weeks before the start of their first Fall semester. As part of the program, Fellows will navigate the Bear River in canoes, camp along the banks, interact with local water and environmental managers, collect channel cross section, stream flow, vegetation cover, and topological complexity data, meet other incoming freshmen, interact with faculty and graduate students, develop boating and leadership skills, problem solve, and participate as full members of the trip team. Subsequently, Fellows will get paid as undergraduate researchers during their Fall and Spring Freshman semesters to analyze, synthesize, and present the field data they collect. The program is a collaborative effort between two USU academic units and the (non-academic) division of Student Services and supports a larger National Science Foundation funded environmental modelling and management project for the lower Bear River, Utah watershed. We have advertised the program via Facebook and emails to incoming USU freshmen, received 35 applications (60% women), and accepted 5 Fellows into the program (3 female and 2 male). The river trip departs August 14, 2012. The poster will overview the Bear River Fellows Program and present qualitative and preliminary outcomes emerging from the trip and Fellows' work through the Fall semester with the field data they collect. We will also undertake more rigorous and longer longitudinal quantitative evaluation of Program outcomes (for example, in problem-solving and leadership) both in Spring 2013 and in subsequent 2013 and 2014 offerings of the

  7. Phenomena and characteristics of barrier river reaches in the middle and lower Yangtze River, China

    Science.gov (United States)

    You, Xingying; Tang, Jinwu

    2017-06-01

    Alluvial river self-adjustment describes the mechanism whereby a river that was originally in an equilibrium state of sediment transport encounters some disturbance that destroys the balance and results in responses such as riverbed deformation. A systematic study of historical and recent aerial photographs and topographic maps in the Middle and Lower Reaches of the Yangtze River (MLYR) shows that river self-adjustment has the distinguishing feature of transferring from upstream to downstream, which may affect flood safety, waterway morphology, bank stability, and aquatic environmental safety over relatively long reaches downstream. As a result, it is necessary to take measures to control or block this transfer. Using the relationship of the occurrence time of channel adjustments between the upstream and downstream, 34 single-thread river reaches in the MLYR were classified into four types: corresponding, basically corresponding, basically not corresponding, not corresponding. The latter two types, because of their ability to prevent upstream channel adjustment from transferring downstream, are called barrier river reaches in this study. Statistics indicate that barrier river reaches are generally single thread and slightly curved, with a narrow and deep cross-sectional morphology, and without flow deflecting nodes in the upper and middle parts of reaches. Moreover, in the MLYR, barrier river reaches have a hydrogeometric coefficient of {}1.2‱, a silty clay content of the concave bank {>}{9.5}%, and a median diameter of the bed sediment {>}{0.158} mm. The barrier river reach mechanism lies in that can effectively centralise the planimetric position of the main stream from different upstream directions, meaning that no matter how the upper channel adjusts, the main stream shows little change, providing relatively stable inflow conditions for the lower reaches. Regarding river regulation, it is necessary to optimise the benefits of barrier river reaches; long river

  8. Ancient Changjiang channel system in the East China Sea continental shelf during the last glaciation

    Institute of Scientific and Technical Information of China (English)

    LI Guangxue; LIU Yong; YANG Zigeng; YUE Shuhong; YANG Wenda; HAN Xibin

    2005-01-01

    Based on the data of high-resolution seismic profiles, an ancient river channel system of the last glaciation occurred along the Zhedong and Xihu depression in the southeast of Hupijiao rise. The distribution of the channel fill system shows that the ancient Changjiang River went through the Changjiang depression into the low land plain of the outside continental shelf during the low sea level cycle of the last glaciation. The big channel fill into Okinawa Trough is not found due to the depletion of the river kinetic energy in the low land plain. The river discharge dispersal was of an important role to the dilution of the northern Okinawa Trough sea at that time. Six ancient river channel systems (A―F), which are main distributaries of ancient Changjiang in the East China Sea continental shelf during the last glaciation, may be buried off the modern Changjiang estuary. The distribution of these channels coincides with the zonal elevations in the sea floor.

  9. SEDIMENT-REMOVING CAPACITY AND RIVER MOTION DYNAMICS

    Institute of Scientific and Technical Information of China (English)

    Zhao-Yin WANG; Yongsheng WU

    2001-01-01

    Unsteady flow in fluvial rivers scours or deposits sediment, and exhibits sediment-removing capaciiy,which is defined as the capacity of the flow to remove sediment from per unit length of a river channel to other places per time. Differing from the well-defined sediment-carrying capacity, which is the feature of the mean flow and explains how much sediment load the flow can transport through the channel, the sediment-removing capacity is the feature of unsteady, non-equilibrium flow and represents the capability of the flow to change the channel shape and location. Measurement of the sediment-removing capacity was performed at 12 cross sections of the wandering lower Yellow River. Analysis demonstrates that the removing capacity depends mainly on the fluctuation intensity of the flow discharge. The power spectrum of discharge is presented with Fourier transformation and it revealed the mechanism of high measurement frequency-high sediment removing capacity. The movement of a river channel within the fluvial plain is defined as the river motion. The patterns of river motion are aggradation, degradation, widening,translation, rotation, wandering, bifurcation, and migration from one channel to another channel. The speed of the river motion is given as a function of the sediment-removing capacity.

  10. Geomorphology of the lower Copper River, Alaska

    Science.gov (United States)

    Brabets, Timothy P.

    1997-01-01

    The Copper River, located in southcentral Alaska, drains an area of more than 24,000 square miles. About 30 miles above its mouth, this large river enters Miles Lake, a proglacial lake formed by the retreat of Miles Glacier. Downstream from the outlet of Miles Lake, the Copper River flows past the face of Childs Glacier before it enters a large, broad, alluvial flood plain. The Copper River Highway traverses this flood plain and in 1995, 11 bridges were located along this section of the highway. These bridges cross parts of the Copper River and in recent years, some of these bridges have sustained serious damage due to the changing course of the Copper River. Although the annual mean discharge of the lower Copper River is 57,400 cubic feet per second, most of the flow occurs during the summer months from snowmelt, rainfall, and glacial melt. Approximately every six years, an outburst flood from Van Cleve Lake, a glacier-dammed lake formed by Miles Glacier, releases approximately 1 million acre-feet of water into the Copper River. When the outflow rate from Van Cleve Lake reaches it peak, the flow of the Copper River will increase between 150,000 to 190,000 cubic feet per second. Data collected by bedload sampling and continuous seismic reflection indicated that Miles Lake traps virtually all the bedload being transported by the Copper River as it enters the lake from the north. The reservoir-like effect of Miles Lake results in the armoring of the channel of the Copper River downstream from Miles Lake, past Childs Glacier, until it reaches the alluvial flood plain. At this point, bedload transport begins again. The lower Copper River transports 69 million tons per year of suspended sediment, approximately the same quantity as the Yukon River, which drains an area of more than 300,000 square miles. By correlating concurrent flows from a long-term streamflow-gaging station on the Copper River with a short-term streamflow-gaging station at the outlet of Miles Lake

  11. Taking the Pulse of a River System: Research on the Upper Mississippi River System

    Science.gov (United States)

    Sauer, Jennifer; Johnson, Barry

    2009-01-01

    Mark Twain raved about the Mississippi River basin as, 'the body of the Nation'. The 'upper body', upstream of the confluence with the Ohio River, includes commercially navigable reaches and branching tributaries that are recreationally and environmentally important. Together they feed and shelter an array of fish and wildlife in their flowing channels, floodplain lakes, backwaters, wetlands, and floodplain forests. Effective river management requires knowledge about factors controlling the dynamics and interactions of important ecosystem components. The Long Term Resource Monitoring Program (LTRMP) is the prized diagnostic tool in the Environmental Management Program for the Upper Mississippi River System that provides critical information about the status and trends of key environmental resources.

  12. Intermittent ephemeral river-breaching

    Science.gov (United States)

    Reniers, A. J.; MacMahan, J. H.; Gallagher, E. L.; Shanks, A.; Morgan, S.; Jarvis, M.; Thornton, E. B.; Brown, J.; Fujimura, A.

    2012-12-01

    In the summer of 2011 we performed a field experiment in Carmel River State Beach, CA, at a time when the intermittent natural breaching of the ephemeral Carmel River occurred due to an unusually rainy period prior to the experiment associated with El Nino. At this time the river would fill the lagoon over the period of a number of days after which a breach would occur. This allowed us to document a number of breaches with unique pre- and post-breach topographic surveys, accompanying ocean and lagoon water elevations as well as extremely high flow (4m/s) velocities in the river mouth during the breaching event. The topographic surveys were obtained with a GPS-equipped backpack mounted on a walking human and show the evolution of the river breaching with a gradually widening and deepening river channel that cuts through the pre-existing beach and berm. The beach face is qualified as a steep with an average beach slope of 1:10 with significant reflection of the incident waves (MacMahan et al., 2012). The wave directions are generally shore normal as the waves refract over the deep canyon that is located offshore of the beach. The tide is mixed semi-diurnal with a range on the order of one meter. Breaching typically occurred during the low-low tide. Grain size is highly variable along the beach with layers of alternating fine and coarse material that could clearly be observed as the river exit channel was cutting through the beach. Large rocky outcroppings buried under the beach sand are also present along certain stretches of the beach controlling the depth of the breaching channel. The changes in the water level measured within the lagoon and the ocean side allows for an estimate of the volume flux associated with the breach as function of morphology, tidal elevation and wave conditions as well as an assessment of the conditions and mechanisms of breach closure, which occurred on the time scale of O(0.5 days). Exploratory model simulations will be presented at the

  13. Food Webs without Borders? Watershed-coast Interactions Influence Diet Sources of Fish in the St. Louis River

    Science.gov (United States)

    Complex ecosystems form where coastal rivers enter the Laurentian Great Lakes. These ecosystems span a river-to-Great Lake transition zone encompassing a mosaic of river channel, drowned river mouth, littoral, wetland and coastal habitats. Our goals were to determine whether we c...

  14. How do big rivers come to be different?

    Science.gov (United States)

    Ashworth, Philip J.; Lewin, John

    2012-08-01

    Big rivers dominate the world's continental surface, yet we are still learning about how they operate and whether they are explicably different, not only from each other, but also from smaller rivers. This paper uses global satellite imagery and ground field-experience to explain and illustrate why and how big rivers are strongly differentiated. At the largest scale, trans-continent sized rivers do not possess unified valley systems created by fluvial erosion but instead involve chains of interlinked domains with contrasted fluvial functions. Alluvial settings are dependent on mainstream and tributary inputs of water and sediment, but big river channel pattern variety is determined by contrasts in sediment feed-rates and differences in the rates and routes of sediment exchange. Four modes of alluvial exchange are recognised: (i) deposition on the floodplain (e.g., levees, infilled palaeochannels and floodbasins), (ii) exchanges involving main channels (e.g., bank erosion and accretion), (iii) deposition within main channels (e.g. bedforms from metres to 10s of kilometres in size), and (iv) material input from tributaries (sediment-rich or sediment-poor). Different combinations of sedimentation activity lead to floodplain morphologies for big rivers that can be classified into four types: (i) lacustrine-dominated, (ii) mainstream-dominated, (iii) tributary or accessory-stream dominated, and (iv) confined or bedrock-dominated. Channel patterning involves a range of main-channel, branch and floodplain styles promoted by variable sediment feeds, complex bed sediment transfers, variable lateral sediment exchanges, plural channel systems and incomplete mineral sedimentation of the hydraulic corridors set by tectonics and prior-valley trenching. In some of the world's largest rivers it is accessory and tributary channels, rather than main-river branches, which determine patterns of floodplain morphology. In some big rivers, but certainly not all, ponded lacustrine

  15. Creating a catchment perspective for river restoration

    Science.gov (United States)

    Benda, L.; Miller, D.; Barquín, J.

    2011-03-01

    One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2), in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we coupled general principles of hydro-geomorphic processes with computer tools to characterize the fluvial landscape. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to topography, valley morphology, river network structure, and fan and terrace landforms. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.

  16. Creating a catchment perspective for river restoration

    Directory of Open Access Journals (Sweden)

    L. Benda

    2011-03-01

    Full Text Available One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2, in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we coupled general principles of hydro-geomorphic processes with computer tools to characterize the fluvial landscape. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to topography, valley morphology, river network structure, and fan and terrace landforms. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.

  17. Estructura de la comunidad íctica en las lagunas del delta exterior del río Magdalena, en relación con la reapertura del canal Clarín (Caribe colombiano Ictic community structure in the laggons of the external delta of the Magdalena river related with the reopening of the Clarin channel (Colombian Caribbean

    Directory of Open Access Journals (Sweden)

    Bateman Vargas Natalia

    1999-11-01

    Full Text Available

    Con el propósito de evaluar el efecto de la reapertura del canal Clarín sobre la comunidad íctica en las lagunas en el Delta exterior del rio Magdalena, se colectaron peces mensualmente en 1S estaciones. Este canal fue abierto con el fin de reestabler el equilibrio hídrico del sistema y con él, su flora y fauna. Las muestras fueron usadas para analizar las variaciones entre tres subregiones: Ciénaga Grande de Santa Marta, Pajarales y Salamanca Occidental y entre dos años (1995 y 1996 uno antes y otro después de la reapertura del canal. Se capturaron 4.161 peces pertenecientes a 59 especies y se encontró la salinidad como el factor ambiental más importante que afecta a la comunidad. El análisis de los datos (clasificación y ordenación y prueba de significancia mostró que las diferencias de la comunidad entre las tres zonas fueron mayores que las diferencias entre los dos años, reflejando el mayor grado de la influencia regional del río Magdalena, respecto a la influencia local del canal Clarín. El año de estudio se caracterizó por los bajos valores de salinidad obtenidos en el área con respecto a años anteriores, lo que hizo que se encontrara abundancia de especies dulceacuícolas.

    In order to evaluate the effect of the the Clarin channel reopening on the fish community around the lagoons of the External Delta of the Magdalena river, fish samples were collected each month in 15 stations. This channel was opened with the purpose to recover the hydric equilibrium in the region and the mangrove forest and fauna. The fish samples were used to analyse the variations of their community structure between three subregions: Cienaga Grande of Santa Marta, Pajarales and Salamanca Occidental and, between the years (1995 and 1996 before and after the Clarin channel opening. A total of 4161 fishes of S9 especies were captured, and the salinity was found the most is (classification and significance test showed that the differences of

  18. 2009/2010年枯水期珠江口磨刀门水道强咸潮分析%Analysis on Severe Saltwater Intrusion in Modaomen Channel of the Pearl River Estuary in Dry Season during 2009-2010

    Institute of Scientific and Technical Information of China (English)

    孔兰; 陈晓宏; 闻平; 刘斌

    2011-01-01

    In this study,measured data was analyzed deeply and three significant characteristics which were "appeared early","fierce" and "affected heavily" were summed up for saltwater intrusion in Modaomen channel of the Pearl River Estuary in the dry season during 2009-2010.The factors of the saltwater intrusion were analyzed,and the results showed that: the main factor for the severe saltwater intrusion of Modaomen channel in the dry season during 2009-2010 was that the precipitation was extremely scarce due to climate change and the runoff dropped sharply in the Pearl River Basin after August 2009;tide was an important driven factor of saltwater intrusion in Modaomen channel,stronger tide led to severe saltwater intrusion;sea-level rise was another important factor to the severe saltwater intrusion in Modaomen channel.In the context of global warming and sea level rising,this study is of great significance for understanding rational development and utilization of fresh water resources in the estuary deeply,especially for the security of water supplies in rural and urban areas of estuary.%研究对翔实的实测数据进行深入分析,总结出2009/2010年枯水期珠江口磨刀门水道咸潮具有出现早、来势猛、影响大的显著特征。通过对此次强咸潮上溯的影响因素进行分析,研究认为:2009年8月以后,气候变化导致的珠江流域降水异常偏少,径流锐减是2009/2010年枯水期珠江口磨刀门水道强咸潮出现的主要原因;潮汐是驱动磨刀门水道咸潮上溯的主要动力因素,潮汐愈强咸潮愈强;海平面上升是磨刀门水道强咸潮出现的重要影响因素。在全球气候变暖和海平面上升的背景下,研究对深入了解河口区淡水资源的合理开发利用,尤其是对保障河口区城乡供水安全具有重要的参考意义。

  19. Contaminant evaluation of shovelnose sturgeon from the Atchafalaya River, Louisiana

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Baseline contaminant levels in shovelnose sturgeon (Scaphirynchus platorynchus) collected from the outfall channel of the Old River Control Structure (ORCS),...

  20. USGS 2015 JSankey Riparian Vegetation and Colorado River

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data include image-based classifications of total vegetation from 1965, 1973, 1984, 1992, 2002, 2004, 2005, and 2009, and characteristics of the river channel...

  1. Use of the RHS method in Golijska Moravica river basin

    Directory of Open Access Journals (Sweden)

    Milanović Ana

    2006-01-01

    Full Text Available River Habitat Survey (RHS is terrain method developed in UK in 1994. for determination of physical character of rivers and river basin. This method is applied for the first time in Golijska Moravica river basin. Two indices which broadly describe the diversity of river habitat and landscape features (Habitat Quality Assessment (HQA and extent and severity of artificial modification to the channel (Habitat Modification Class (HMC has been developed for reporting purposes. These are based on simple scoring systems which have been agreed by technical experts.

  2. River predisposition to ice jams: a simplified geospatial model

    OpenAIRE

    Munck, Stéphane; Gauthier, Yves; Bernier, Monique; Chokmani, Karem; Légaré, Serge

    2016-01-01

    The goal of this work was to develop a simplified geospatial model to estimate the predisposition of any river channel to ice jams. Rather than predicting river ice break up, the main question here was to predict where the broken up ice is susceptible to jam based on the river’s geomorphological characteristics. Thus, six parameters referred to potential causes for ice jams in the literature were selected: presence of an island, narrowing of the channel, high sinuosity, presence of a bridge, ...

  3. Grays River Watershed Geomorphic Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Geist, David R

    2005-04-30

    This investigation, completed for the Pacific Northwest National Laboratory (PNNL), is part of the Grays River Watershed and Biological Assessment commissioned by Bonneville Power Administration under project number 2003-013-00 to assess impacts on salmon habitat in the upper Grays River watershed and present recommendations for habitat improvement. This report presents the findings of the geomorphic assessment and is intended to support the overall PNNL project by evaluating the following: The effects of historical and current land use practices on erosion and sedimentation within the channel network The ways in which these effects have influenced the sediment budget of the upper watershed The resulting responses in the main stem Grays River upstream of State Highway 4 The past and future implications for salmon habitat.

  4. Height and wavelength of alternate bars in rivers: Modelling vs. laboratory experiments

    NARCIS (Netherlands)

    Knaapen, M.A.F.; Hulscher, S.J.M.H.; Vriend, de H.J.; Harten, van A.

    2001-01-01

    Alternate bars are large wave patterns in sandy beds of rivers and channels. The crests and troughs alternate between the banks of the channel. These bars, which move downstream several meters per day, reduce the navigability of the river. Recent modelling of alternate bars has focused on stability

  5. Geomorphology and flood-plain vegetation of the Sprague and lower Sycan Rivers, Klamath Basin, Oregon

    Science.gov (United States)

    O'Connor, James E.; McDowell, Patricia F.; Lind, Pollyanna; Rasmussen, Christine G.; Keith, Mackenzie K.

    2015-01-01

    This study provides information on channel and flood-plain processes and historical trends to guide effective restoration and monitoring strategies for the Sprague River Basin, a primary tributary (via the lower Williamson River) of Upper Klamath Lake, Oregon. The study area covered the lower, alluvial segments of the Sprague River system, including the lower parts of the Sycan River, North Fork Sprague River, South Fork Sprague River, and the entire main-stem Sprague River between the confluence of the North Fork Sprague and the South Fork Sprague Rivers and its confluence with the Williamson River at Chiloquin, Oregon. The study included mapping and stratigraphic analysis of flood-plain deposits and flanking features; evaluation of historical records, maps and photographs; mapping and analysis of flood-plain and channel characteristics (including morphologic and vegetation conditions); and a 2006 survey of depositional features left by high flows during the winter and spring of 2005–06.

  6. Raft River Geothermal Aquaculture Experiment. Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, D.K.; Rose, F.L.; Kent, J.C.; Watson, L.R.; Sullivan, J.F.

    1979-08-01

    Channel catfish, tilapia and Malaysian prawns were cultured directly in geothermal water for approximately seven months at the Department of Energy, Raft River Geothermal Site, to evaluate the organisms throughout a grow-out cycle. Parameters evaluated included survival, growth, bioaccumulation of metals and fluoride, collagen synthesis, and bone calcium levels. Growth at Raft River was slightly lower than at a companion commercial facility at Buhl, Idaho, but was attributed to facility differences rather than an adverse impact of geothermal water. No significant differences were recorded between Raft River and Buhl fish for bone calcium or collagen concentrations. No significant accumulation of heavy metals by fish or prawns was recorded.

  7. 桥梁建设与河道行洪纳潮的适应性分析%Analysis of adaptability for bridge construction and river channel for coursing flood and tide

    Institute of Scientific and Technical Information of China (English)

    徐林春; 赵明登; 张庭荣; 何书琴

    2012-01-01

    Taking a grand bridge engineering for example,the method of combination of one-dimensional river network mathematical model and local river 2-D tidal flow mathematical model is used to calculate and analyze the influence of the bridge on river coursing flood and tide.The problem of adaptability for bridge construction and river coursing flood and tide is discussed from layout of axis,elevation of beam at the bridge bottom,form of pier and cushion cap,combination of the bridge span,degree of water resistance,relation between the pier of the bridge and the dike,etc.Some general suggestions about the arrangement of the bridge pier and cushion cap are proposed to make the bridge construction to adapt the ability of the river flood and tide as far as possible;and the suggestions can be provided to the department of water administration as a reference for administrative licensing.%以某特大桥为例,采用大范围一维网河数学模型与工程局部河道平面二维潮流数学模型相结合的方法,对该特大桥的行洪、纳潮影响进行了计算和分析.从大桥工程的轴线布置、梁底标高、墩台形式、桥跨组合、阻水程度、建设项目与堤防关系等方面论述了跨河桥梁建设与河道行洪、纳潮之间的适应性问题.为减少桥梁建设对河道行洪、纳潮的影响,从桥梁墩台布置等方面提出了指导性建议,使桥梁建设尽可能与河道行洪、纳潮能力相适应,也为水行政主管部门的行政许可提供参考.

  8. On geo-basis of river regulation-A case study for the middle reaches of the Yangtze River

    Institute of Scientific and Technical Information of China (English)

    LIU GuoWei

    2008-01-01

    From the point of view that people have to obey the river's geo-attributes in the river regulation,the definition and the meaning of the geo-attributes of a river are discussed.The geo-basis of the river regulation of the middle reaches of the Yangtze River is expounded in five aspects,including the structural geomorphol-ogy environment of flood storage and discharge,the distribution characteristics of subsidence and the sedimentation areas of Dongting Basin,the history evolution of Jianghan Basin,the function of Jianghan Basin and Dongting Basin as the flood water detention areas of Jingjiang River reach in ancient time,and the geological characteristic of Jingjiang River reach.Based on the geo-attributes of the middle reaches of the Yangtze River,some ideas about the middle reach regulation of the Yangtze River are put forward:to process the interchange between the lakes and diked marsh areas in Dongting Basin,to canal the new river route as the flood di-version channel of Jingjiang River reach with the paleo river,to recover the func-tion of Jianghan Basin as flood detention area of the middle reaches.And we should take into consideration the geo-environment of the whole Yangtze River in the river regulation of middle reaches.

  9. 78 FR 77591 - Drawbridge Operation Regulation; Shark River, NJ

    Science.gov (United States)

    2013-12-24

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; Shark River, NJ AGENCY: Coast Guard... Shark River (South Channel), mile 0.8, at Belmar, NJ. The deviation is necessary to facilitate the... facilitate the replacement of motor seals and instrumentation on the bridge. The Route 71 Bridge across...

  10. River predisposition to ice jams: a simplified geospatial model

    Science.gov (United States)

    De Munck, Stéphane; Gauthier, Yves; Bernier, Monique; Chokmani, Karem; Légaré, Serge

    2017-07-01

    Floods resulting from river ice jams pose a great risk to many riverside municipalities in Canada. The location of an ice jam is mainly influenced by channel morphology. The goal of this work was therefore to develop a simplified geospatial model to estimate the predisposition of a river channel to ice jams. Rather than predicting the timing of river ice breakup, the main question here was to predict where the broken ice is susceptible to jam based on the river's geomorphological characteristics. Thus, six parameters referred to potential causes for ice jams in the literature were initially selected: presence of an island, narrowing of the channel, high sinuosity, presence of a bridge, confluence of rivers, and slope break. A GIS-based tool was used to generate the aforementioned factors over regular-spaced segments along the entire channel using available geospatial data. An ice jam predisposition index (IJPI) was calculated by combining the weighted optimal factors. Three Canadian rivers (province of Québec) were chosen as test sites. The resulting maps were assessed from historical observations and local knowledge. Results show that 77 % of the observed ice jam sites on record occurred in river sections that the model considered as having high or medium predisposition. This leaves 23 % of false negative errors (missed occurrence). Between 7 and 11 % of the highly predisposed river sections did not have an ice jam on record (false-positive cases). Results, limitations, and potential improvements are discussed.

  11. EXPERIMENTAL INVESTIGATIONS ON LONGITUDINAL DISPERSION CHARACTERISTICS OF TIDAL RIVERS

    Institute of Scientific and Technical Information of China (English)

    Fan Jing-yu; Wang Dao-zeng; Zhong Bao-chang

    2003-01-01

    The longitudinal dispersion characteristics of tidal rivers are experimentally investigated in a water channel. The longitudinal dispersion features and influential factors on pollutant in various stages of a tidal period in natural rivers are studied, the value ranges and variation trends of the longitudinal dispersion coefficient are obtained by means of concentration measurement. The results can provide important parameters for establishing the water quality mathematical models in tidal rivers.

  12. THE DEGREE OF SILTING AND THE IMPACT ON ALLUVIAL DEPOSITS IN THE RIVER BEDS OF BISTRIŢA RIVER BASIN

    OpenAIRE

    COJOC MARIA GEANINA; ROMANESCU GH.; TIRNOVAN ALINA

    2014-01-01

    Since 1960 the Bistriţa River basin came under the profound influence of anthropic incidence. This river basin represents a pattern of use for hydropower potential: reservoirs (9); channels (61 km); water dams; transfers of flows; protection structures works for banks and slopes; relocation of human settlements (13 villages); gravel pits; galleries; viaducts; communication paths, etc. Bistriţa River development has led to significant changes in the structure of the hydrological regime, throug...

  13. 10 years after the largest river restoration project in Northern Europe

    DEFF Research Database (Denmark)

    Astrup Kristensen, Esben Astrup; Kronvang, B.; Wiberg-Larsen, P.;

    2014-01-01

    The lower river Skjern (Denmark) historically contained a large variation in habitats and the river ran through large areas with wetlands, many backwaters, islands and oxbow lakes. During the 1960s the river was channelized and the wetland drained. A restoration during 2001–2002 transformed 19 km...

  14. What controls sediment flux in dryland channels?

    Science.gov (United States)

    Michaelides, K.; Singer, M. B.

    2010-12-01

    Theories for the development of longitudinal and grain size profiles in perennial fluvial systems are well developed, allowing for generalization of sediment flux and sorting in these fluvial systems over decadal to millennial time scales under different forcings (e.g., sediment supply, climate changes, etc). However, such theoretical frameworks are inadequate for understanding sediment flux in dryland channels subject to spatially and temporally discontinuous streamflow, where transport capacity is usually much lower than sediment supply. In such fluvial systems, channel beds are poorly sorted with weak vertical layering, poorly defined bar forms, minimal downstream fining, and straight longitudinal profiles. Previous work in dryland channels has documented sediment flux at higher rates than their humid counterparts once significant channel flow develops, pulsations in bed material transport under constant discharge, and oscillations in dryland channel width that govern longitudinal patterns in erosion and deposition. These factors point to less well appreciated controls on sediment flux in dryland valley floors that invite further study. This paper investigates the relative roles of hydrology, bed material grain size, and channel width on sediment flux rates in the Rambla de Nogalte in southeastern Spain. Topographic valley cross sections and hillslope and channel particle sizes were collected from an ephemeral-river reach. Longitudinal grain-size variation on the hillslopes and on the channel bed were analysed in order to determine the relationship between hillslope supply characteristics and channel grain-size distribution and longitudinal changes. Local fractional estimates of bed-material transport in the channel were calculated using a range of channel discharge scenarios in order to examine the effect of channel hydrology on sediment transport. Numerical modelling was conducted to investigate runoff connectivity from hillslopes to channel and to examine the

  15. Probability of Hazardous Substance Spills on Saint Clair/Detroit River System

    Science.gov (United States)

    1982-11-01

    3.07 Ice accumulations begin in the southern section of Lake Huron at the entrance to the St. Clair River. During freezeup ice jams in the narrow...section of the channel and can slow or stop navigation until the ice stabilizes and becomes shorefast. At freezeup brash ice may fill the channel to the...Marine Operations Manager reports that in a mild winter, the river is clear. Sometimes the river becomes clogged with brash ice at freezeup . If this

  16. Efficient incorporation of channel cross-section geometry uncertainty into regional and global scale flood inundation models

    NARCIS (Netherlands)

    Neal, J. C.; Odini, Nicolas; trigg, mark; Freer, Jim; garcia-pintado, javier; mason, david; Wood, Melissa; Bates, P. D.

    2015-01-01

    This paper investigates the challenge of representing structural differences in river channel cross-section geometry for regional to global scale river hydraulic models and the effect this can have on simulations of wave dynamics. Classically, channel geometry is defined using data, yet at larger

  17. Ice Jams on the Little Missouri River, North Dakota and North Platte River, Nebraska

    Science.gov (United States)

    Pang, B. P.; Brookman, D. A.

    2004-12-01

    During the winter months, rivers in the north central United States have a phenomenon occurring, which is known as "ice jams". The initial melting of the river ice causes broken ice buildup, which acts as a quasi-dam restricting the natural flow. Ice jams severely impact ecosystems and are known to cause extensive damage to the channels, as well as man-made structures. The focus of this paper is on ice jams on the Little Missouri River in North Dakota and the North Platte River in Nebraska. Previous investigations done on the Lower Platte River valley, as well as the Missouri River basin, have shown that the primary cause of ice jams on these rivers is due to the spring thaw. The initial portion of the paper will discuss the pattern of ice jams on these rivers, as well as some mitigation strategies for control of these ice jams. The second section will deal with the modeling of ice jams on these river systems using HEC-RAS. This model will be comprised of both two and three-dimensional aspects of the rivers.

  18. The contemporary geomorphology of the Letaba River in the Kruger National Park

    Directory of Open Access Journals (Sweden)

    B.P. Moon

    2001-07-01

    Full Text Available The Letaba River drains part of Northern Province in north-east South Africa. Its catchment has been modified significantly by human activity which has affected the flow regime; it experiences only ephemeral flows through the Kruger National Park to its confluence with the Olifants River. Although the Letaba is similar to the other rivers in the Kruger National Park in that it displays some bedrock influenced channel features, increased sediment delivery from the degraded catchment upstream has resulted in extensive alluviation within the channel. Sections of channel flowing over bedrock with no sediment covering are rare, and the river comprises a series of channel types: mixed anastomosing, alluvial braided, mixed pool-rapid and alluvial single thread. Each is characterised by a different combination of morphological units which relate to the degree of alluviation in the channel. These channel types are described in detail and inferences are made concerning their formation and maintenance from field observation and measurement.

  19. Tidal river dynamics: Implications for deltas

    Science.gov (United States)

    Hoitink, A. J. F.; Jay, D. A.

    2016-03-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity intrusion, a realm that can extend inland hundreds of kilometers. One key phenomenon resulting from this interaction is the emergence of large fortnightly tides, which are forced long waves with amplitudes that may increase beyond the point where astronomical tides have become extinct. These can be larger than the linear tide itself at more landward locations, and they greatly influence tidal river water levels and wetland inundation. Exploration of the spectral redistribution and attenuation of tidal energy in rivers has led to new appreciation of a wide range of consequences for fluvial and coastal sedimentology, delta evolution, wetland conservation, and salinity intrusion under the influence of sea level rise and delta subsidence. Modern research aims at unifying traditional harmonic tidal analysis, nonparametric regression techniques, and the existing understanding of tidal hydrodynamics to better predict and model tidal river dynamics both in single-thread channels and in branching channel networks. In this context, this review summarizes results from field observations and modeling studies set in tidal river environments as diverse as the Amazon in Brazil, the Columbia, Fraser and Saint Lawrence in North America, the Yangtze and Pearl in China, and the Berau and Mahakam in Indonesia. A description of state-of-the-art methods for a comprehensive analysis of water levels, wave propagation, discharges, and inundation extent in tidal rivers is provided. Implications for lowland river deltas are also discussed in terms of sedimentary deposits, channel bifurcation, avulsion, and salinity intrusion, addressing contemporary research challenges.

  20. Geomorphic Effects of Engineered Log Jams in River Restoration, Middle Fork John Day River

    Science.gov (United States)

    Duffin, J.; McDowell, P. F.

    2014-12-01

    The Middle Fork of the John Day River (MFJD) Intensively Monitored Watershed in eastern Oregon is a multi-phase restoration implementation and monitoring project. MFJD is a tributary to the Colombia and is part of one of the longest free flowing rivers systems in the continental United States. It is a gravel and cobble bed river with a drainage area of 2,100 km2. The river has endured extensive channel and floodplain degradation from years of channel alteration and straightening due to human influences including dredge mining, ranching, and farming. As part of the river restoration project on the MFJD, engineered log jams have been constructed to address many of the restoration goals including creating scour pools, inhibiting bank erosion, creating and maintaining a sinuous river planform, and increasing complexity of fish habitat. There is a need for more detailed understanding on ELJ channel morphologic effects and how site-specific characteristics and differences in log jam infrastructure interact to create the in-channel features over timescales longer than a few years. This study uses detailed channel bed topographic surveys collected either with a total station or RTK-GPS technology. Geomorphic change detection techniques are utilized to monitor topographic change under and around the 26 log structures in two different river reaches over a six to seven year period The log structures are often associated with deepening of pools as desired, but also some structures show sedimentation under the structure. Differences in the patterns will be assessed based on the design, location, and specific characteristics of the log structures; variables include number and placement of logs, volume of structure, location on meander bend, and sediment sizes.

  1. A Review of Integrated River Basin Management for Sarawak River

    Directory of Open Access Journals (Sweden)

    Kuok K. Kuok

    2011-01-01

    Full Text Available Problem statement: Sarawak River was a life-sustaining water source for the residents in Kuching City and surrounding areas. Raw water is treated at Batu Kitang Water Treatment Plant (BKWTP that supplies more than 98% of the total water production in Kuching City. The raw water supply to BKWTP is not adequate to meet the ever increasing water demand. In order to overcome this problem, four projects had been implemented along Sarawak River for managing and securing water supply to BKWTP. Approach: These four projects are construction of 1.5m height storage weir across Sungai Sarawak Kiri river channel, Kuching Barrage and Shiplock, Bengoh Dam and Kuching Centralized Wastewater Management System (KCWMS. In 2005, 1.5 m height submersible weir was constructed across Sungai Sarawak Kiri channel for increasing the safe yield that can last until year 2010. Kuching Barrage and Shiplock were commissioned in 2000 as barrier to avoid the saline intrusion reaching upper catchment. 24 telemetry stations were installed along Sarawak River for monitoring and regulating the water level. This will preserve high quality water storage at upper catchment of Sarawak River. In year 2010, Bengoh Dam was constructed to ensure adequate raw water will be supplied to BKWTP for meeting the increasing water demand from 2010-2030. This reservoir will store 144 million m3 of fresh water covering reservoir area of 8.77km2. Beyond 2030, the water supply shall not depend solely on fresh water. Results: Black and grey water in Sarawak Catchment was treated through Kuching Centralized Wastewater Management System (KCWMS and recycled for daily used. Conclusion: The treated water that comply Standard A water quality, can distribute for domestic, industrial and irrigation used in nearest future. This will reduce the water demand solely on raw water and create a sustainable living in Kuching City. Beyond 2030, a few alternatives are also proposed for conserving and

  2. On geo-basis of river regulation——A case study for the middle reaches of the Yangtze River

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    From the point of view that people have to obey the river’s geo-attributes in the river regulation, the definition and the meaning of the geo-attributes of a river are discussed. The geo-basis of the river regulation of the middle reaches of the Yangtze River is expounded in five aspects, including the structural geomorphology environment of flood storage and discharge, the distribution characteristics of subsidence and the sedimentation areas of Dongting Basin, the history evolution of Jianghan Basin, the function of Jianghan Basin and Dongting Basin as the flood water detention areas of Jingjiang River reach in ancient time, and the geological characteristic of Jingjiang River reach. Based on the geo-attributes of the middle reaches of the Yangtze River, some ideas about the middle reach regulation of the Yangtze River are put forward: to process the interchange between the lakes and diked marsh areas in Dongting Basin, to canal the new river route as the flood diversion channel of Jingjiang River reach with the paleo river, to recover the function of Jianghan Basin as flood detention area of the middle reaches. And we should take into consideration the geo-environment of the whole Yangtze River in the river regulation of middle reaches.

  3. 2012 Reassessment of Floodplain Wetland Connections in the Middle Green River, Utah

    Energy Technology Data Exchange (ETDEWEB)

    LaGory, Kirk E. [Argonne National Lab. (ANL), Argonne, IL (United States); Walston, Leroy J. [Argonne National Lab. (ANL), Argonne, IL (United States); Weber, Cory C. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-12-01

    This report presents the results of floodplain wetland connection surveys conducted in 2012 at eight priority floodplain wetlands along the middle Green River between Jensen and Ouray, Utah. Surveys were conducted at levee breaches and within channels leading from the breaches to the wetlands (referred to here as connection channels) to characterize the flows needed to connect the river's main channel with the floodplain wetlands.

  4. The Huanghe (Yellow) River: Recent changes and its countermeasures

    Science.gov (United States)

    Yu, Liansheng

    2006-11-01

    Since the 1960s a series of large reservoirs have been built in the upper and middle reaches of the Huanghe River. Changes caused by these reservoirs include a decrease in flood discharge and sediment load to the lower reaches and conversely, an increase of the silt concentration in the river water. This accumulation of silt in the river channel is a serious problem in the lower Huanghe River and has caused abnormal and distorted flow courses in the river bed. These effects include: shrinkage of the river channel, frequent dewatering (i.e., zero flow) in the river-mouth area, and hanging rivers (i.e., a river channel elevated above its floodplain). The zero-flow portion of the river has gradually extended upstream for nearly the entire 700 km of the lower reach. Utilization of the floodplains for agriculture and temporary villages has become a major problem. To counter these changes and situations, new measures, new methodology, and new thinking must be adapted incorporating results from the recent works on sediment transport and accumulation. Water conservancy works (dams, pumping stations, siphon-intakes, etc.) are typically used for adjustment of river water and sediment discharges and for irrigation and hydro-power generation. Recently, they are also being used to conduct tests using the reservoir water/sediment mix to flush out sediments deposited in the channel bed and transport the sediment to places where it is needed or into the Bohai Sea. Additionally, the future of the new deltaic sub-lobe in the Bohai Sea (developed in 1996) and the present estuary needs to be considered with respect to future development.

  5. REVIEW OF REGIME THEORY OF ALLUVIAL CHANNELS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    One of the most important problems in river engineering is to determine a stable cross section geomenry and slope for an alluvial channel. This has been the subject of considerable research for about a century and continues to be of great practical interest. Lgnoring plan geometry, an alluvi-al channel can adjust its slope, depth and width, to develop a dynamic stable condition in which it can transport a certain a-mount of water and sediment. The brief history of regime the-ory and its new development are reviewed in this paper.

  6. Hydraulic Geometry of a tidally influenced delta channel network: the Mahakam Delta, East Kalimantan, Indonesia

    Science.gov (United States)

    Sassi, M.; Hoitink, A.; de Brye, B.; Deleersnijder, E.

    2011-12-01

    Hydraulic Geometry (HG) refers to relations between the characteristics of channels in a network, including mean depth, width, and bed slope, and the discharge conveyed by the channel during bank-full conditions. HG relations are of fundamental importance to water management in channel networks, and they bear an interesting relation with geomorphology. River delta channel networks typically scale according to HG relations such as log(A) ~ p*log(Q), where A is channel cross sectional area, Q water discharge, and the exponent p is in between 0.8 and 1.2. In tidal networks, the tidal prism or tidal discharge can be used, instead of a discharge with a constant frequency of occurrence. In the tidal case, the exponent often shows the same range of variation. Tidal rivers are intrinsically complex, as tidal propagation is influenced by river discharge and vice-versa. Consequently, channel geometry in tidally influenced river deltas may show a mixed scaling behavior of river and tidal channel networks, as the channel forming discharges may both be of river and tidal origin. In tidal regions, the tidal dynamics may lead to a cyclic variation in water discharge distribution at bifurcations, readily affecting HG relations. We present results from the Mahakam delta channel network in Indonesia, a tide-river dominated delta which has been prograding for 60 km over the last 5000 years. Bathymetric surveys were conducted over the distributary network and connected tidal channels. Based on a geomorphic analysis of the present distributary network, we show that channel geometry of the fluvial distributary network scales with bifurcation order. The bifurcation order does not feature a clear relation with bifurcate branch length or bifurcate width ratio, as in the case of river deltas. HG relations of the area of selected cross-sections are well represented by the tidal prism or by the river discharge, when scaled with the bifurcation order. Numerical simulations show that river

  7. Aggravation of north channels' shrinkage and south channels' development in the Yangtze Estuary under dam-induced runoff discharge flattening

    Science.gov (United States)

    Zhu, Bo-yuan; Li, Yi-tian; Yue, Yao; Yang, Yun-ping

    2017-03-01

    Construction of dams on rivers has progressively affected the seasonal variability of runoff discharge, which has consequently produced remarkable impacts on the morphology of estuarine channels. This paper considers four-typical-order bifurcations of the Yangtze Estuary and adopts an ebb partition ratio (defined as the diversion ratio of ebb flow in a given branch divided by the total ebb tidal discharge immediately upstream of the river node where the bifurcation occurs) as a measure of water excavating force in the bifurcation channels. Results show that the seasonal variability of runoff discharge at Datong Hydrological Station (Datong) is flattened, being mainly driven by upstream runoff flattening observed at Yichang Hydrological Station (Yichang) and the tributary rivers. Yearly ebb partition ratios of the channels located to the north and south of the islands present decreasing and increasing trends respectively, and as also do the yearly north and south channel volume of the bifurcations. Yearly ebb partition ratio is proved to be an effective index to represent the water excavating force considering the stability of yearly ebb tidal discharge and its relationship with the channel erosion-deposition. River dams are the driving factors behind the runoff flattening at Datong because of their flattening effects on its main contributors (Yichang and tributary rivers). This flattening significantly helps reduce and enlarge the yearly ebb partition ratios of the north and south channels respectively, and then aggravates the shrinkage and development of the north and south channels separately. Yearly ebb partition ratio of the North Passage (NP) must be enlarged in order for the NP to maintain its function as a shipping channel.

  8. The Mississippi River: A place for fish

    Science.gov (United States)

    Schramm, Harold; Ickes, Brian; Chen, Yushun; Chapman, Duane C.; Jackson, John; Chen, Daqing; Li, Zhongjie; Kilgore, Jack; Phelps, Quinton; Eggleton, Michael

    2016-01-01

    The Mississippi River flows 3,734 km from its source at Lake Itasca, Minnesota to its outlet at the Gulf of Mexico. Along its course, it collects water from portions of two Canadian provinces and 41 % of the conterminous United States. Although greatly altered for navigation and flood control throughout much of its length, the Mississippi River remains an important fishery resource that provides habitat for 188 species of fishes and recreational and commercial fishing opportunities. The objectives of this chapter are to describe the contemporary fisheries habitat throughout the Mississippi River, identify how management to achieve human benefits influences the fishes and their habitats, and summarize efforts to conserve and enhance fish habitat. The 826-km headwater reach is entirely in Minnesota and remains largely unaltered. The reaches that extend 1,059 km from St. Anthony Falls, Minnesota to above the confluence with the Missouri River near St. Louis, Missouri have been altered by impoundment that has affected floodplain function, increased sedimentation of backwaters, and homogenized the formerly diverse aquatic habitats. After the confluence with the Missouri River, the Mississippi River flows freely for 1,849 km to the Gulf of Mexico. The alterations of the free-flowing reaches of greatest significance to the fisheries resource are reducing the duration and height of the flood pulse as a consequence of shortening the river channel, disconnection of the river from its historic and present floodplain, and loss of secondary channel-island complexes. Engineering features to improve commercial navigation have also added habitat and, when wisely manipulated, can be used to rehabilitate habitat. Some aspects of water quality have improved, but legacy chemicals and nutrient-laden inflows and sediments remain problems. Although true restoration in the sense of restoring all environmental conditions to an unaltered state is unlikely, the future value of the

  9. On river cross-sectional change in the Niger Delta

    Science.gov (United States)

    Abam, T. K. S.; Omuso, W. O.

    2000-08-01

    A network of dominantly distributary river systems dissects the superficial deposits of the Niger Delta comprising alluvial sediments. Changes in river cross-sections are instigated mainly by bank failures, fluctuations in discharge, and bed degradation by fluvial processes. The relative importance of factors causing river cross-sectional change was ranked, based on a deterministic sensitivity technique involving partial differentiation of soil properties, flow characteristics, and geometrical parameters of the river channels. Analysis suggests that steep bank inclination and high flow velocity/discharge are the major causes of cross-sectional change, while interlocking of soil grains is the major erosion-restraining factor. Sensitivity coefficients were used further to generate susceptibility indices, indicating the vulnerability of channel cross-sections to change. Based on this, the risks of channel cross-sectional change were compared at different sites.

  10. a Linear Model for Meandering Rivers with Arbitrarily Varying Width

    Science.gov (United States)

    Frascati, A.; Lanzoni, S.

    2011-12-01

    Alluvial rivers usually exhibit quite complex planforms, characterized by a wide variety of alternating bends, that have attracted the interest of a large number of researchers. Much less attention has been paid to another striking feature observed in alluvial rivers, namely the relatively regular spatial variations attained by the channel width. Actively meandering channels, in fact, generally undergo spatial oscillations systematically correlated with channel curvature, with cross sections wider at bends than at crossings. Some other streams have been observed to exhibit irregular width variations. Conversely, rivers flowing in highly vegetated flood plains, i.e. canaliform rivers, may exhibit an opposite behavior, owing to the combined effects of bank erodibility and floodplain depositional processes which, in turn, are strictly linked to vegetation cover. Similarly to streamline curvatures induced by bends, the presence of along channel width variations may have remarkable effects on the flow field and sediment dynamics and, thereby, on the equilibrium river bed configuration. In particular, spatial distribution of channel curvature typically determines the formation of a rhythmic bar-pool pattern in the channel bed strictly associated with the development of river meanders. Channel width variations are on the contrary characterized by a sequence of narrowing, yielding a central scour, alternated to the downstream development of a widening associated with the formation of a central bar. Here we present a morphodynamic model that predict at a linear level the spatial distribution of the flow field and the equilibrium bed configuration of an alluvial river characterized by arbitrary along channel distributions of both the channel axis curvature and the channel width. The mathematical model is averaged over the depth and describes the steady, non-uniform flow and sediment transport in sinuous channels with a noncohesive bed. The governing two-dimensional equations

  11. River discharge estimation through MODIS data

    Science.gov (United States)

    Tarpanelli, Angelica; Brocca, Luca; Lacava, Teodosio; Faruolo, Mariapia; Melone, Florisa; Moramarco, Tommaso; Pergola, Nicola; Tramutoli, Valerio

    2011-11-01

    River discharge is an important quantity of the hydrologic cycle because it is essential for both scientific and operational applications related to water resources management and flood risk prevention. Streamflow measurements are sparse and for few sites along natural channels and, hence, they are not able to detect adequately the complexity of variation in surface water systems. Therefore, in recent years, the possibility to obtain river discharge estimates through remote sensing monitoring has received a great interest. In this context, the capability of the MODerate resolution Imaging Spectroradiometer (MODIS) for river discharge estimation is investigated here. Thanks to a very short revisiting time interval and a moderate spatial resolution (up to 250 m), MODIS has a significant potential for mapping flooded area extent and flow dynamics. Specifically, for the estimation of river discharge, the ratio of the MODIS channel 2 reflectance values between two pixels located within and outside the river is used. Time series of daily discharge between 2006 and 2010 measured at two gauging stations located along the Upper Tiber River basin (central Italy) are employed to test the procedure. The agreement between MODIS-derived and in situ discharge time series is found to be fairly good with correlation coefficient values close to 0.8.

  12. Bedform dynamics in a large sand-bedded river using multibeam echo sounding

    Science.gov (United States)

    Elliott, C. M.; Jacobson, R. B.; Erwin, S.; Eric, A. B.; DeLonay, A. J.

    2014-12-01

    High-resolution repeat multibeam Echo Sounder (MBES) surveys of the Lower Missouri River in Missouri, USA demonstrate sand bedform movement at a variety of scales over a range of discharges. Understanding dune transport rates and the temporal and spatial variability in sizes across the channel has implications for how sediment transport measurements are made and for understanding the dynamics of habitats utilized by benthic organisms over a range of life stages. Nearly 800 miles of the Lower Missouri River has been altered through channelization and bank stabilization that began in the early 1900's for navigation purposes. Channelization of the Lower Missouri River has created a self-scouring navigation channel with large dunes that migrate downstream over a wide range of discharges. Until the use of MBES surveys on the Missouri River the spatial variability of dune forms in the Missouri River navigation channel was poorly understood. MBES surveys allow for visualization of a range of sand bedforms and repeat measurements demonstrate that dunes are moving over a wide range of discharges on the river. Understanding the spatial variability of dunes and dune movement across the channel and in different channel settings (bends, channel cross-overs, near channel structures) will inform emerging methods in sediment transport measurement that use bedform differencing calculations and provide context for physical bedload sediment sampling on large sand-bedded rivers. Multiple benthic fish species of interest including the endangered pallid sturgeon utilize Missouri River dune fields and adjacent regions for migration, feeding, spawning, early development and dispersal. Surveys using MBES and other hydroacoustic tools provide fisheries biologists with broad new insights into the functionality of bedforms as habitat for critical life stages of large river fish species in the Missouri River, and similar sand-bedded systems.

  13. FLOOD ROUTING MODELS IN CONFLUENT AND DIVIDING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    范平; 李家春; 刘青泉

    2004-01-01

    By introducing a water depth connecting formula, the hydraulic equations in the dividing channel system were coupled and the relation of discharge distribution between the branches of the dividing channels can be yielded. In this manner, a numerical model for the confluent channels was established to study the variation of backwater effects with the parameters in the channel junction. The meeting of flood peaks in the mainstream and tributary can be analyzed with this model. The flood peak meeting is found to be a major factor for the extremely high water level in the mainstream during the 1998 Yangtze River flood. Subsequently the variations of discharge distribution and water level with channel parameters between each branch in this system were studied as well. As a result, flood evolution caused by Jingjiang River shortcut and sediment deposition in the entrance of dividing channels of the Yangtze River may be qualitatively elucidated. It is suggested to be an effective measure for flood mitigation to enhance regulation capability of reservoirs available upstream of the tributaries and harness branch entrance channels.

  14. Bathymetry of the Hong and Luoc River Junction, Red River Delta, Vietnam, 2010

    Science.gov (United States)

    Kinzel, Paul J.; Nelson, Jonathan M.; Toan, Duong Duc; Thanh, Mung Dinh; Shimizu, Yasuyuki

    2012-01-01

    The U.S. Geological Survey, in collaboration with the Water Resources University in Hanoi, Vietnam, conducted a bathymetric survey of the junction of the Hong and Luoc Rivers. The survey was done to characterize the channel morphology of this delta distributary network and provide input for hydrodynamic and sediment transport models. The survey was carried out in December 2010 using a boat-mounted multibeam echo sounder integrated with a global positioning system. A bathymetric map of the Hong and Luoc River junction was produced which was referenced to the datum of the Trieu Duong tide gage on the Luoc River.

  15. Geomorphological Impacts of an extreme Flood in Karoon River, Iran

    Science.gov (United States)

    Yousefi, Saleh; Mirzaee, Somaya; Keesstra, Saskia; Piegay, Herve; Pourghasemi, Hamid Reza

    2017-04-01

    An extreme flood occurred on 14.04.2016 in Kroon River. Using the OLI Landsat images on 08.04.2016 (before flood) and 24.04.2016 (after flood) the morphological evolution in different land cover types by this flood event were detected. The results show that the event significantly affected the channel width. The main effect was the high mobilization of channel sediments and severe bank erosion in the studied meandering reach. According to field surveys, the flood occupied the whole channel corridor and even some of the flood plain parts, but the channel pattern was not markedly changed. Results show the average of active channel width increased from 192 m to 256 m respectively for before and after flood. Statistical results indicate a significant change for active channel width and sinuosity index at 99% confidence level for both indexes. Findings show that the channel morphological changes (channel widening) varied significantly in different land cover types along the Karoon River banks. Specifically, the channel has widened less in the residential areas than the other land cover types, which is the result of bank protection activities. Keywords: Remote sensing, fluvial geomorphology, floodplain management, river evolution.

  16. Bar dynamics and bifurcation evolution in a modelled braided sand-bed river

    NARCIS (Netherlands)

    Schuurman, Filip|info:eu-repo/dai/nl/328235830; Kleinhans, Maarten G.|info:eu-repo/dai/nl/217675123

    2015-01-01

    Morphodynamics in sand-bed braided rivers are associated with simultaneous evolution of mid-channel bars and channels on the braidplain. Bifurcations around mid-channel bars are key elements that divide discharge and sediment. This, in turn, may control the evolution of connected branches, with

  17. Effect of Water and Sediment Regulation on Lower Yellow River

    Institute of Scientific and Technical Information of China (English)

    XU Guobin; SI Chundi

    2009-01-01

    According to the results of the water and sediment regulations of the Yellow River in year 2002-2007, the effect of erosion and deposition on the lower reaches, the amount and distribution of erosion and deposition in the river mouth area, the adjustment of river regime, the effect of river regulation projects and changes of flowing capacity of the channel are analyzed. It is revealed that the water and sediment regulation is efficient to reduce deposition and improve the flowing capacity and the conditions of sediment transport.

  18. Mobile radio channels

    CERN Document Server

    Pätzold, Matthias

    2011-01-01

    Providing a comprehensive overview of the modelling, analysis and simulation of mobile radio channels, this book gives a detailed understanding of fundamental issues and examines state-of-the-art techniques in mobile radio channel modelling. It analyses several mobile fading channels, including terrestrial and satellite flat-fading channels, various types of wideband channels and advanced MIMO channels, providing a fundamental understanding of the issues currently being investigated in the field. Important classes of narrowband, wideband, and space-time wireless channels are explored in deta

  19. Seasonal variability of the phytoplankton community of a lateral channel (Cortado of the Upper Paraná River Dinâmica sazonal da comunidade fitoplanctônica de um canal lateral (Canal Cortado do Alto Rio Paraná (PR, Brasil

    Directory of Open Access Journals (Sweden)

    Márcia Divina de Oliveira

    2000-05-01

    Full Text Available The seasonal variability of the phytoplanktonic community was studied in one lateral channel of the Upper Paraná River. The extensive samplings (monthly were taken in three stations in the Cortado Channel (22º47‘30”S, 53º24‘37”W from March of 1993 to February of 1994. Temporal changes in taxonomic composition, density, biomass, diversity and dominance were analyzed in relation to regional climate and hydrology, and to the physical and chemical factors of the water column. The phytoplanktonic community was composed of 95 taxa. The classes Cyanophyceae (Anabaena circinalis and Bacillariophyceae (Aulacoseira granulata were the most abundant, being responsible for the biomass peaks that occurred. The temporal variation in density and biomass did not show a clear seasonality, however, the highest biomass occurred in the late low waters (limnophase, with dominance of microplankton. Nanoplanktonic species, C-strategists common in Paraná River, mainly Cryptomonas brasiliensis, were abundant throughout the study periodFoi estudada a variabilidade sazonal da comunidade fitoplanctônica de um canal lateral do Alto Rio Paraná. As amostragens extensivas (mensais foram efetuadas em três estações no canal Cortado (22º47‘30”S, 53º24‘37”W no período de março de 1993 a fevereiro de 1994. As flutuações temporais na composição taxonômica, densidade, biomassa, diversidade e dominância foram analisadas em relação aos fatores climáticos e hidrológicos regionais e aos fatores físicos e químicos da água. A comunidade fitoplanctônica esteve representada por 95 táxons. As classes Cyanophyceae (Anabaena circinalis e Bacillariophyceae (Aulacoseira granulata foram as mais abundantes, sendo responsáveis pelos picos de biomassa registrados. As variações temporais na densidade, diversidade e biomassa não apresentaram conspícua sazonalidade. A máxima biomassa, entretanto, ocorreu ao término do período de águas baixas (limnofase

  20. Bathymetric surveys of the Neosho River, Spring River, and Elk River, northeastern Oklahoma and southwestern Missouri, 2016–17

    Science.gov (United States)

    Hunter, Shelby L.; Ashworth, Chad E.; Smith, S. Jerrod

    2017-09-26

    In February 2017, the Grand River Dam Authority filed to relicense the Pensacola Hydroelectric Project with the Federal Energy Regulatory Commission. The predominant feature of the Pensacola Hydroelectric Project is Pensacola Dam, which impounds Grand Lake O’ the Cherokees (locally called Grand Lake) in northeastern Oklahoma. Identification of information gaps and assessment of project effects on stakeholders are central aspects of the Federal Energy Regulatory Commission relicensing process. Some upstream stakeholders have expressed concerns about the dynamics of sedimentation and flood flows in the transition zone between major rivers and Grand Lake O’ the Cherokees. To relicense the Pensacola Hydroelectric Project with the Federal Energy Regulatory Commission, the hydraulic models for these rivers require high-resolution bathymetric data along the river channels. In support of the Federal Energy Regulatory Commission relicensing process, the U.S. Geological Survey, in cooperation with the Grand River Dam Authority, performed bathymetric surveys of (1) the Neosho River from the Oklahoma border to the U.S. Highway 60 bridge at Twin Bridges State Park, (2) the Spring River from the Oklahoma border to the U.S. Highway 60 bridge at Twin Bridges State Park, and (3) the Elk River from Noel, Missouri, to the Oklahoma State Highway 10 bridge near Grove, Oklahoma. The Neosho River and Spring River bathymetric surveys were performed from October 26 to December 14, 2016; the Elk River bathymetric survey was performed from February 27 to March 21, 2017. Only areas inundated during those periods were surveye