Sample records for aguas fluviales utilizando

  1. 4, 719745, 2007 Fluvial organic

    E-print Network

    Paris-Sud XI, Université de

    been focussed upon estimating total fluvial losses of organic carbon in the form of DOC (dissolvedHESSD 4, 719­745, 2007 Fluvial organic carbon flux from an eroding peatland R. R. Pawson et al System Sciences Fluvial organic carbon flux from an eroding peatland catchment, southern Pennines, UK R

  2. Quaternary fluvial archives: achievements of the Fluvial Archives Group

    NASA Astrophysics Data System (ADS)

    Bridgland, David; Cordier, Stephane; Herget, Juergen; Mather, Ann; Vandenberghe, Jef; Maddy, Darrel

    2013-04-01

    In their geomorphological and sedimentary records, rivers provide valuable archives of environments and environmental change, at local to global scales. In particular, fluvial sediments represent databanks of palaeoenvironment and palaeoclimatic (for example) of fossils (micro- and macro-), sedimentary and post-depositional features and buried soils. Well-dated sequences are of the most value, with dating provided by a wide range of methods, from radiometric (numerical) techniques to included fossils (biostratigraphy) and/or archaeological material. Thus Quaternary fluvial archives can also provide important data for studies of Quaternary biotic evolution and early human occupation. In addition, the physical disposition of fluvial sequences, be it as fragmented terrace remnants or as stacked basin-fills, provides valuable information about geomorphological and crustal evolution. Since rivers are long-term persistent features in the landscape, their sedimentary archives can represent important frameworks for regional Quaternary stratigraphy. Fluvial archives are distributed globally, being represented on all continents and across all climatic zones, with the exception of the frozen polar regions and the driest deserts. In 1999 the Fluvial Archives Group (FLAG) was established, as a working group of the Quaternary Research Association (UK), aimed at bringing together those interested in such archives. This has evolved into an informal organization that has held regular biennial combined conference and field-trip meetings, has co-sponsored other meetings and conference sessions, and has presided over two International Geoscience Programme (IGCP) projects: IGCP 449 (2000-2004) 'Global Correlation of Late Cenozoic Fluvial Deposits' and IGCP 518 (2005-2007) 'Fluvial sequences as evidence for landscape and climatic evolution in the Late Cenozoic'. Through these various activities a sequence of FLAG publications has appeared, including special issues in a variety of journals, amassing a substantial volume of information on fluvial archives worldwide. This presentation will highlight some of these data and will describe important patterns observed and interpretations arising therefrom.

  3. Laser Scanning Applications in Fluvial Geomorphology

    NASA Astrophysics Data System (ADS)

    Alho, P.

    2014-12-01

    During recent decades, the use of high-resolution laser scanning data in fluvial studies has rapidly increased. Airborne laser scanning (ALS) can be used to extensively map riverine topography. Laser scanning data have great potential to improve the effectiveness of topographical data acquisition and the accuracy and resolution of DTMs (Digital Terrain Models) needed in fluvial geomorphology. Airborne Laser Scanning (ALS) is applicable for mapping areas varying from reach to catchment scale and these data are, therefore, particularly suitable, especially for hydraulic modelling, mapping of flood inundation, and the detection of macro-scale fluvial geomorphology. With Terrestrial Laser Scanning (TLS) a spatial resolution of less than 1 mm and a range accuracy of few millimetres can be achieved. Mobile Laser Scanning (MLS) enables a remarkably faster survey approach compared to the conventional TLS method. One of the newest applications of MLS approaches involves a boat/cart/backpack -based mobile mapping system. This set-up includes laser scanning and imaging from a platform moving along a river course or floodplain and may be used to expand the spatial extent of terrestrial scanning. Detailed DTMs derived from laser scanning data can be used to improve the recognition of fluvial landforms, the geometric data of hydraulic modelling, and the estimation of flood inundation extents and the associated fluvial processes. Fluvial environments also offer challenges for the application of laser scanning techniques. Factors such as vegetation cover, terrain undulation, coarse surface materials and water surfaces may distort a laser scanning survey.

  4. The Modification of Mars Fluvial Surfaces

    NASA Technical Reports Server (NTRS)

    Bourke, M. C.; Zimbelman, J. R.; Finnegan, D.; Banerdt, B.

    2001-01-01

    The identification of fluvial deposits on Mars is impaired by modifying geological processes. An analysis of surface patterns of superimposed dunes and channels in paleoflood environments in Washington State and Australia can yield information on buried surfaces. Additional information is contained in the original extended abstract.

  5. A Field Exercise in Fluvial Sediment Transport.

    ERIC Educational Resources Information Center

    Tharp, Thomas M.

    1983-01-01

    Describes an investigation which introduces the mathematical principles of stream hydraulics and fluvial sediment in a practical context. The investigation has four stages: defining hydrology of the stream; defining channel hydraulics in a study reach; measuring grain size; and calculating transportable grain size and comparing measure stream-bed…

  6. Martian Fluvial Conglomerates at Gale Crater

    NASA Astrophysics Data System (ADS)

    Williams, R. M. E.; Grotzinger, J. P.; Dietrich, W. E.; Gupta, S.; Sumner, D. Y.; Wiens, R. C.; Mangold, N.; Malin, M. C.; Edgett, K. S.; Maurice, S.; Forni, O.; Gasnault, O.; Ollila, A.; Newsom, H. E.; Dromart, G.; Palucis, M. C.; Yingst, R. A.; Anderson, R. B.; Herkenhoff, K. E.; Le Mouélic, S.; Goetz, W.; Madsen, M. B.; Koefoed, A.; Jensen, J. K.; Bridges, J. C.; Schwenzer, S. P.; Lewis, K. W.; Stack, K. M.; Rubin, D.; Kah, L. C.; Bell, J. F.; Farmer, J. D.; Sullivan, R.; Van Beek, T.; Blaney, D. L.; Pariser, O.; Deen, R. G.; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Minitti, Michelle; Cremers, David; Edgar, Lauren; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; King, Penelope; Blank, Jennifer; Weigle, Gerald; Schmidt, Mariek; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Ehlmann, Bethany; Farley, Kenneth; Griffes, Jennifer; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Rice, Melissa; Siebach, Kirsten; Stolper, Edward; Brunet, Claude; Hipkin, Victoria; Léveillé, Richard; Marchand, Geneviève; Sobrón Sánchez, Pablo; Favot, Laurent; Cody, George; Steele, Andrew; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Aparicio, Carlos Armiens; Caride Rodríguez, Javier; Carrasco Blázquez, Isaías; Gómez Gómez, Felipe; Elvira, Javier Gómez; Hettrich, Sebastian; Lepinette Malvitte, Alain; Marín Jiménez, Mercedes; Frías, Jesús Martínez; Soler, Javier Martín; Torres, F. Javier Martín; Molina Jurado, Antonio; Sotomayor, Luis Mora; Muñoz Caro, Guillermo; Navarro López, Sara; González, Verónica Peinado; García, Jorge Pla; Rodriguez Manfredi, José Antonio; Planelló, Julio José Romeral; Alejandra Sans Fuentes, Sara; Sebastian Martinez, Eduardo; Torres Redondo, Josefina; O'Callaghan, Roser Urqui; Zorzano Mier, María-Paz; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Fabre, Cécile; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Bish, David; Schieber, Juergen; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; Uston, Claude d.; Lasue, Jérémie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Szopa, Cyril; Robert, François; Sautter, Violaine; Nachon, Marion; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; Clegg, Sam; Cousin, Agnès; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Treiman, Allan; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Summons, Roger; Goesmann, Fred; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Dyar, M. Darby; Fassett, Caleb; Blake, David F.; Bristow, Thomas; DesMarais, David; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Bleacher, Lora; Brinckerhoff, William; Choi, David; Conrad, Pamela; Dworkin, Jason P.; Eigenbrode, Jennifer; Floyd, Melissa; Freissinet, Caroline; Garvin, James; Glavin, Daniel; Harpold, Daniel; Mahaffy, Paul; Martin, David K.

    2013-05-01

    Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcrop show a predominantly feldspathic composition, consistent with minimal aqueous alteration of sediments. Sediment was mobilized in ancient water flows that likely exceeded the threshold conditions (depth 0.03 to 0.9 meter, average velocity 0.20 to 0.75 meter per second) required to transport the pebbles. Climate conditions at the time sediment was transported must have differed substantially from the cold, hyper-arid modern environment to permit aqueous flows across several kilometers.

  7. Lowland fluvial phosphorus altered by dams

    NASA Astrophysics Data System (ADS)

    Zhou, Jianjun; Zhang, Man; Lin, Binliang; Lu, Pingyu

    2015-04-01

    Dams affect ecosystems, but their physical link to the variations in fluvial fluxes and downstream ecological consequences are inadequately understood. After estimating the current effects of the Three Gorges project and other reservoirs upstream on the Yangtze River on the fluvial phosphorus (P) in the middle and lower Yangtze River, we further investigated the long-term effects of dams on the fluvial regimes of P and P-enriched sediment (PES). Simultaneously measured P distributions with sediment size (PDSS) from the Three Gorges Reservoir (TGR) proved that the areal density of particulate P (PP) bound on graded sediment can be measured using the surface area concentration of the total sediment. A PDSS relationship is obtained and the selective transport and long-term sedimentation of P are simulated using a nonuniform suspended sediment model, which incorporates the PDSS formula. The computations revealed that a reservoir would significantly lower the downstream availability of P in the dry season and promote high pulses of P in summer when the reservoir is flushed as sedimentation accumulates. As a result, the P buffering and replenishing mechanism in the pristine ecosystem from upstream supplies and local re-suspension are permanently eliminated when a regulating reservoir is built upstream. This change is irreversible if reservoir regulation continues. Changes could potentially aggravate the existing P-limitation, decrease the water's ability to adjust nutrient/pollutant fluctuations, accumulate a greater surplus of carbon and nitrogen, and even exacerbate blooms in favorable conditions.

  8. GEOG 4210: Fluvial and Hydrological Processes GEOG 6210: Advanced Fluvial and Hydrological Processes

    E-print Network

    Lecce, Scott A.

    be at least 10-15 references, and they should consist of relevant journal articles and books (NOT newspaper geomorphology. Although the course will examine hydrologic and fluvial theory, we will also address applied.........................25% Research project.................25% The topic of the graduate student's research project

  9. Metapopulation capacity of evolving fluvial landscapes

    NASA Astrophysics Data System (ADS)

    Bertuzzo, Enrico; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2015-04-01

    The form of fluvial landscapes is known to attain stationary network configurations that settle in dynamically accessible minima of total energy dissipation by landscape-forming discharges. Recent studies have highlighted the role of the dendritic structure of river networks in controlling population dynamics of the species they host and large-scale biodiversity patterns. Here, we systematically investigate the relation between energy dissipation, the physical driver for the evolution of river networks, and the ecological dynamics of their embedded biota. To that end, we use the concept of metapopulation capacity, a measure to link landscape structures with the population dynamics they host. Technically, metapopulation capacity is the leading eigenvalue ?M of an appropriate "landscape" matrix subsuming whether a given species is predicted to persist in the long run. ?M can conveniently be used to rank different landscapes in terms of their capacity to support viable metapopulations. We study how ?M changes in response to the evolving network configurations of spanning trees. Such sequence of configurations is theoretically known to relate network selection to general landscape evolution equations through imperfect searches for dynamically accessible states frustrated by the vagaries of Nature. Results show that the process shaping the metric and the topological properties of river networks, prescribed by physical constraints, leads to a progressive increase in the corresponding metapopulation capacity and therefore on the landscape capacity to support metapopulations—with implications on biodiversity in fluvial ecosystems.

  10. Model Simulations of Fluvial Incision in Parana Basin

    NASA Astrophysics Data System (ADS)

    Barnhart, C. J.; Howard, A. D.; Moore, J. M.

    2007-07-01

    A landform evolution model is used to explore scenarios responsible for the late-Noachian early-Hesperian fluvial incision on the Southern Highlands. Simulation DEMs are statistically compared to actual DEMs in order to evaluate working hypotheses.

  11. Titan's Impact Craters and Associated Fluvial Features

    NASA Astrophysics Data System (ADS)

    Gilliam, A.; Jurdy, D. M.

    2012-12-01

    The Cassini spacecraft has detected remarkably few impact craters on the surface of Titan. By early 2010, with surface radar coverage reaching 33%, seven certain impact craters were discovered, with another 52 nearly certain and probable ones. The paucity of craters implies that the surface of Titan is very dynamic and relatively young. Dynamical models of the internal structure of Titan suggest the possibility of a subsurface ocean of ammonia-water liquid beneath its icy shell. If a large subsurface ocean does exist, it should have measurable effects on Titan's surface and the morphology of its craters. Using a combination of available Cassini radar-SAR, ISS, and VIMS data, we construct geomorphologic maps of Titan's "certain" impact craters with associated features we interpret as fluvial in origin. The best example, Menrva, a 445 km wide double-ring impact basin, hosts a complex network of channels. On the western, more degraded side of the crater, channels cut through the outer rim. To the east of Menrva, a curious network of channels start near the rim crest and appear to have flowed away into a large catchment basin; the complex is termed Elivagar Flumina. Channels surrounding Menrva display a low order - a classification of stream segments based on the number of tributaries upstream - measuring one or two, occasionally up to three. This matches observations of two other confirmed impact craters with associated fluvial features. A halo of low-order channels encircles Selk, an 80 km diameter crater with a small central peak. Also, Ksa, a 30 km diameter crater with a bright central peak and radial ejecta, has a feature that appears to be a first order channel. These differ radically from the tree-shaped dendritic channels common on Titan, which are generally attributed to heavy rainfall. For example, the Xanadu region, as observed on the T13 swath, exhibits a very complex and dendritic network of channels, where the order of channels reaches six to seven. The extensive area covered by dendritic systems indicates an origin from rainfall, rather than seepage of subsurface liquids, which has a low stream order. Thus, we argue that the association of channels with Titan's largest craters may not be pluvial in origin, and instead may be the result of seepage or even record a flood initiated by a large impact.

  12. THEMIS Observations of Fluvial Landforms on Mars

    NASA Astrophysics Data System (ADS)

    Rice, J. W.; Christensen, P. R.; Malin, M. C.; McEwen, A. S.

    2002-12-01

    The THEMIS (Thermal Emission Imaging System) instrument onboard Mars Odyssey is providing both visible and infra-red imaging observations of the martian surface at two scales (18 m/p and 100 m/p respectively). IR observations are being conducted during both day and night. IR imagery records temperature variations which are primarily due to differences in abundances of rocks, indurated materials, sand, and dust on the surface. All of the major outflow channels, valley networks and fossae related channel systems have been imaged thus far in the mission. Outflow Channels: the source regions contain large blocks of chaotic terrain with very coarse (rocky) slopes and talus aprons while the tops of these blocks appear smooth and mantled with finer grained materials (dust). A similar relationship is also seen on the large mesas and buttes near the mouths of several outflow channels (Kasei and Ma'Adim Valles). Channel floor regions located near the mouths of some outflow channels (Ares, Maja, and Kasei Valles) appear to be very rocky. This is most likely the result of deep erosion and stripping of the bedrock by plucking and scouring from high velocity flows. However, Tiu Vallis doesn't show this type of stripping. This may be due to waning stage deposition of fines, and or lower flow velocities and shallower channel incision, which failed to reach the bedrock material. Some streamlined islands (Ares, Athabasca and Mangala Valles) have coarse (rocky) prows, flanks and tails. These may be deposits of coarse bedload (boulders) or erosion and exposure of the rocky material which makes up the islands. Preliminary observations of some islands suggest that these are depositional rather than erosional bedforms. Valley Networks: layers are commonly seen in the upper regions of the walls of these systems. Narrow, incised, discontinuous inner channels with finer grained materials are also seen on the floors of some valley networks (Bahram and Nanedi Valles). Maumee Vallis appears to have pendant shaped features (bars?) near the mouth. Samara Vallis and an unnamed channel have terminal deposits located at their mouths (fans?). Valley network dissection also appears much more prevalent in some regions (Libya Montes) than has ever been seen before. Fossae related channel systems, such as Athabasca, Granicus, Hebrus, and Hrad Valles; and Olympica and Hephaestus Fossae, located near the Tharsis and Elysium volcanic provinces have also been studied. These channels systems are most likely the result of volcano ground ice/water interactions. This makes these systems high priority geologic and astrobiologic targets for future landed missions. Preliminary observations and geologic interpretations of martian fluvial landforms will be presented; early results indicate that Mars has had a very rich and complex fluvial history.

  13. Fluvial erosion on Mars: Implications for paleoclimatic change

    NASA Technical Reports Server (NTRS)

    Gulick, Virginia C.; Baker, Victor R.

    1993-01-01

    Fluvial erosion on Mars has been nonuniform in both time and space. Viking orbiter images reveal a variety of different aged terrains exhibiting widely different degrees of erosion. Based on our terrestrial analog studies, rates of fluvial erosion associated with the formation of many of the valleys on Mars is probably on the order of hundreds of meters per million years, while rates of erosion associated with the formation of the outflow channels probably ranged from tens to hundreds of meters in several weeks to months. However, estimated rates of erosion of the Martian surface at the Viking Lander sites are extremely low, on the order of 1 micron/yr or less. At most this would result in a meter of material removed per million years, and it is unlikely that such an erosion rate would be able to produce the degree of geomorphic work required to form the fluvial features present elsewhere on the surface. In addition, single terrain units are not eroded uniformly by fluvial processes. Instead fluvial valleys, particularly in the cratered highlands, typically are situated in clusters surrounded by vast expanses of uneroded surfaces of the same apparent lithologic, structural, and hydrological setting. Clearly throughout its geologic history, Mars has experienced a nonuniformity in erosion rates. By estimating the amount of fluvial erosion on dissected terrains and by studying the spatial distribution of those locations which have experienced above normal erosion rates, it should be possible to place further constraints on Mars' paleoclimatic history.

  14. Bar morphodynamics in the tidally-influenced fluvial zone

    NASA Astrophysics Data System (ADS)

    Parsons, Daniel; Ashworth, Philip; Best, James; Nicholas, Andrew; Prokocki, Eric; Sambrook-Smith, Greg; Keevil, Claire; Sandbach, Steve

    2015-04-01

    The hydrodynamics and deposits of the Tidally-Influenced Fluvial Zone (TIFZ) are complex because it experiences competing fluvial and tidal flows and spatially and temporally variable rates of sediment transport and deposition. This paper presents a new integrated field dataset from the Columbia River Estuary, USA, that quantifies the morphodynamic response the bed morphology and bar stratigraphy to fluvial-tidal flows. A 3-year, field and modelling program that started in 2011, has been monitoring the dynamics and deposits of a 40 km-reach of the Columbia River Estuary. Data obtained so far throughout the TIFZ include: bathymetry using MBES, flow using ADCP, subsurface sedimentology using GPR and shallow coring to 5 m. Initial results from the programme suggest there is a complex spatial and temporal lag in the response of the bed morphology and deposits to the fluvial-tidal flows. Zones of strong ebb and flood flow do not necessarily produce channel beds dominated by bi-directional bedforms. Many mid-channel bars are stable over decadal time periods. This paper will illustrate the variety in bar morphologies and channel change throughout the fluvial-tidal zone and contrast these bar dynamics with examples from purely fluvial environments.

  15. Linking fluvial bed sediment transport across scales

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Meerschaert, Mark M.; Packman, Aaron I.

    2012-10-01

    We present a new random walk model for bed load sediment transport that explains the scale-dependency generally observed in transport rates and captures the transient anomalous dispersion often seen in rivers. Particles alternate between mobile and resting phases, with a tempered stable probability distribution for both particle step length and resting time. Tempered fractional mobile-immobile differential equations model the ensemble average of particle dynamics. The model is tested against data from three sediment dispersion experiments. Using tempering in both space and time, the new model is able to capture the full range of observed ensemble particle dynamics. The random walk model illuminates the physical meaning of all transport parameters in the mobile-immobile equations and explains transitions between observed super-diffusive, sub-diffusive, and regular diffusive ensemble particle dynamics. By explicitly predicting the effects of spatial and temporal averaging on particle dynamics, this method can be used to link observations of fluvial sediment dynamics across scales. This approach is also generally applicable to a wide variety of geophysical and ecological dynamics, such as ecological dispersal, pathogen transmission in rivers, nutrient export from watersheds, and large-scale geomorphodynamics associated with infrequent phenomena such as avalanches and turbidity currents.

  16. Reconstructing Holocene fluvial activity in Ireland using alluvial radiocarbon dates

    NASA Astrophysics Data System (ADS)

    Turner, Jonathan; Macklin, Mark; Jones, Anna

    2010-05-01

    Advances in fluvial geochronologies and multi-proxy environmental correlatives are providing increasingly robust models of river response to Holocene environmental change. At the forefront of recent scientific progress is the development and analysis of databases of fluvial radiocarbon dates, where particular emphasis is given to terminus post quem (‘change after') radiocarbon dates that mark the onset of alluviation linked to episodes of enhanced flooding. Here we report on the first attempt to apply these meta-analysis techniques to dated fluvial deposits in Ireland, which offer tremendous potential for recording climate changes associated with shifts in meridional atmospheric circulation, largely free from the effects of continentality in the east. The resulting Irish fluvial radiocarbon database is considerably smaller than examples from other European countries, such as Germany, Poland, Spain and the UK, and a patchy geographical distribution of dated sites across Ireland highlights the relative dearth of Irish fluvial research up to now. Despite a comparatively small number of significant ‘change after' radiocarbon dates, however, the application of generic meta-analysis techniques reveals a pattern of Holocene flooding that is consistent with widely cited palaeoclimate proxies for regional temperature and precipitation. The Irish flood record also closely matches that derived from an established and much larger UK radiocarbon database, thereby corroborating the growing body of evidence that supports an underlying climate forcing of fluvial activity during much of the Holocene. Fluvial systems in Ireland are shown to be sensitive to climate, but the majority of major radiocarbon-dated flooding episodes appear to lag the UK by ca. 100 years. Although this may be the result of database precision, we suggest that the hydrological buffering and sponge effects of widespread peatland cover across Ireland may have impeded hydrological connectivity during Holocene flooding episodes. In addition, this investigation reveals systematically lower sedimentation rates across Ireland compared to the UK, which may have reduced the geomorphic effectiveness of fluvial sediment archives to record major flood events. These considerations, together with an increasing focus on regional variations in fluvial activity across the Holocene, can only be properly addressed with a more concerted and expanded programme of Holocene fluvial research in Ireland.

  17. Seismic modeling of fluvial reservoirs in outcrop

    SciTech Connect

    Campbell, E. (IGG-TNO, Delft (Netherlands))

    1993-09-01

    Three-dimensional (3-D) seismics and concomitant improvements in processing techniques have increased the amount of reservoir-scale information that can be obtained from the seismic waveform reaching the surface. However, the geological significance of these seismic events remains unclear. The seismic modeling of reservoir formations in outcrops allows analogs to be drawn to the seismic response of reservoirs at depth. Previous outcrop modeling studies are mostly high-frequency approximations, suitable for large-scale geometrical imaging but unsuitable for imaging lateral variations in lithology and geometry of bodies that lie on or below the [open quotes]visual[close quotes] resolution of the seismic tool. This study examines finite-difference seismic modeling of Tertiary, fluvial-sandstone bodies in outcrop from central Spain. The outcrops were well known from reservoir characterization studies, easily accessible, and well exposed. Outcrop geometry was converted into a finite-difference grid, with density and velocity values coming from measurements of cores and blocks from each of the lithologies. Synthetic traces were generated. The traces were then processed in the conventional manner. Full solution of the wave equation allows all wave types to be modeled, e.g., diffraction sand multiples. Models were generated to simulate reservoir conditions at the surface and at depth. Seismic wave-forms could then be related back to reservoir characteristics. Seismic modeling of reservoir sands in outcrop can aid in the interpretation of such bodies at depth. Seismic modeling of reservoirs is a low-cost interpretation tool that may aid field development by delineation of reservoirs in area of complex sedimentology where surface analogs exist.

  18. Accommodation controls on fluvial-deltaic reservoir architecture

    SciTech Connect

    Gardner, M.H.; Willis, B.J.; Barton, M.D. [Univ. of Texas, Austin, TX (United States)

    1995-08-01

    Hydrocarbon recovery efficiency is controlled by reservoir heterogeneities resulting from geometric arrangements of strata, or {open_quotes}stratal architecture{close_quotes}. Traditional reservoir characterization relates depositional systems to stratal architecture. High-resolution sequence stratigraphy of outcrop analogs provides a chronostratigraphic framework for evaluating accommodation conditions of depositional systems. Key stratigraphic surfaces and/or correlative strata define a hierarchy of chronostratigraphic units of different periodicities. The Upper Cretaceous Ferron Sandstone, an analog to high accommodation and sediment supply fluvial-deltaic reservoirs, comprises an intermediate-term stratigraphic sequence consisting of seven short-term stratigraphic cycles. Each short-term stratigraphic cycle contains fluvial- to storm-dominated shallow-marine deposits laterally replaced by distributary channel deposits. The Lower Cretaceous Fall River Formation, an analog to low accommodation fluvial-deltaic reservoirs, comprises an intermediate-term stratigraphic sequence consisting of six short-term stratigraphic cycles. Detailed outcrop study of valley fill strata shows unconformities controlling permeability distributions, segregating the reservoir, and juxtaposing low and high permeability strata. Hence, in low accommodation fluvial-deltaic strata the most important stratal element affecting fluid flow are unconformity bounded short-term stratigraphic cycles. This contrasts with high accommodation fluvial-deltaic strata where smaller-scale depositional elements comprising individual short-term stratigraphic cycles form flow units.

  19. Evidence from Fluvial Deposits for Changes in Water Surface Levels of a Sea or Large Lake at Aeolis Dorsa, Mars

    NASA Astrophysics Data System (ADS)

    Cardenas, B. T.; Mohrig, D.

    2014-07-01

    Fluvial deposits at Aeolis Dorsa are arranged in a stratigraphic sequence common to the fluvial fill of incised valleys on Earth. On Earth, this type of fluvial stratigraphy is a common response to ocean level falls and rises.

  20. Fluvial network organization imprints on microbial co-occurrence networks

    PubMed Central

    Widder, Stefanie; Besemer, Katharina; Singer, Gabriel A.; Ceola, Serena; Bertuzzo, Enrico; Quince, Christopher; Sloan, William T.; Rinaldo, Andrea; Battin, Tom J.

    2014-01-01

    Recent studies highlight linkages among the architecture of ecological networks, their persistence facing environmental disturbance, and the related patterns of biodiversity. A hitherto unresolved question is whether the structure of the landscape inhabited by organisms leaves an imprint on their ecological networks. We analyzed, based on pyrosequencing profiling of the biofilm communities in 114 streams, how features inherent to fluvial networks affect the co-occurrence networks that the microorganisms form in these biofilms. Our findings suggest that hydrology and metacommunity dynamics, both changing predictably across fluvial networks, affect the fragmentation of the microbial co-occurrence networks throughout the fluvial network. The loss of taxa from co-occurrence networks demonstrates that the removal of gatekeepers disproportionately contributed to network fragmentation, which has potential implications for the functions biofilms fulfill in stream ecosystems. Our findings are critical because of increased anthropogenic pressures deteriorating stream ecosystem integrity and biodiversity. PMID:25136087

  1. Progressive Poleward Migration of Fluvial Processes on Titan

    NASA Astrophysics Data System (ADS)

    Moore, Jeffrey M.; Howard, A. D.

    2012-04-01

    Titan may have acquired its massive atmosphere relatively recently in solar system history. The warming sun may have been key to generating Titan’s atmosphere over time, starting from a thin atmosphere with condensed surface volatiles like Triton, with increased luminosity releasing methane, and then large amounts of nitrogen (perhaps suddenly), into the atmosphere This thick atmosphere, initially with much more methane than at present, resulted in global fluvial erosion that has over time retreated towards the poles with the removal of methane from the atmosphere. Basement rock, as manifested by bright, rough, ridges, scarps, crenulated blocks, or aligned massifs, mostly appears within 30° of the equator. This landscape was intensely eroded by fluvial processes as evidenced by numerous valley systems, fan-like depositional features and regularly-spaced ridges (crenulated terrain). Much of this bedrock landscape, however, is mantled by dunes, suggesting that fluvial erosion no longer dominates in equatorial regions. High mid-latitude regions on Titan exhibit dissected sedimentary plains at a number of localities, suggesting deposition (perhaps by sediment eroded from equatorial regions) followed by erosion. These dissected plains may be evidence for the poleward retreat of rain erosion. The polar regions are mainly dominated by deposits of fluvial and lacustrine sediment. Fluvial processes are active in polar areas as evidenced by alkane lakes and occasional cloud cover. Figure 1. High mid-latitude region exhibiting a partially-dissected surface (“Dissected Plateau”). The dissection is interpreted to be fluvial due to dendritic valleys draining southward. The undissected surface to the left “Upper Plain” may be alluvial lowlands or an undissected part of the plateau bordering it to the right. The smooth radar-dark surface in center right is suggested to be “Alluvial Lowlands” because it is crossed by several broad, sinuous valleys or channels (arrow). Portion of swath T39, ~50°S, 210°W.

  2. Fluvial-deltaic sedimentation and stratigraphy of the ferron sandstone

    USGS Publications Warehouse

    Anderson, P.B.; Chidsey, T.C., Jr.; Ryer, T.A.

    1997-01-01

    East-central Utah has world-class outcrops of dominantly fluvial-deltaic Turonian to Coniacian aged strata deposited in the Cretaceous foreland basin. The Ferron Sandstone Member of the Mancos Shale records the influences of both tidal and wave energy on fluvial-dominated deltas on the western margin of the Cretaceous western interior seaway. Revisions of the stratigraphy are proposed for the Ferron Sandstone. Facies representing a variety of environments of deposition are well exposed, including delta-front, strandline, marginal marine, and coastal-plain. Some of these facies are described in detail for use in petroleum reservoir characterization and include permeability structure.

  3. Bank stability analysis for fluvial erosion and mass failure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The central objective of this study was to highlight the differences in magnitude between mechanical and fluvial streambank erosional strength with the purpose of developing a more comprehensive bank stability analysis. Mechanical erosion and ultimately failure signifies the general movement or coll...

  4. Modeling fluvial erosion on regional to continental scales

    Microsoft Academic Search

    Alan D. Howard; William E. Dietrich; Michele A. Seidl

    1994-01-01

    The fluvial system is a major concern in modeling landform evolution in response to tectonic deformation. Three stream bed types (bedrock, coarse-bed alluvial, and fine-bed alluvial) differ in factors controlling their occurrence and evolution and in appropriate modeling approaches. Spatial and temporal transitions among bed types occur in response to changes in sediment characteristics and tectonic deformation. Erosion in bedrock

  5. Fluvial sedimentation following Quaternary eruptions of Mount St. Helens, Washington

    Microsoft Academic Search

    R. J. Janda; D. F Meyer

    1985-01-01

    Depositional records of convulsive volcanic events at Mount St. Helens are in many places obscured by rapid fluvial erosion and deposition close to the volcano. Some major eruptions are recorded primarily by lahars and alluvium deposited tens of kilometers away. About 35 percent of the distinctive hummocky topography of the 1980 North Fork Toutle debris avalanche deposit now resembles an

  6. Architectural studies of Jurassic-Cretaceous fluvial units, Colorado Plateau

    SciTech Connect

    Miall, A.D.; Bromley, M.H.; Cowan, E.J.; Turner-Peterson, C.E.

    1989-03-01

    A sixfold hierarchy of architectural elements and bounding surfaces evolved from outcrop studies of three fluvial units: Westwater Canyon member (WCM), Morrison Formation, Upper Jurassic; Torrivio sandstone member (TSM), Gallup Sandstone, Upper Cretaceous, northwestern New Mexico; and Kayenta Formation (KF), Lower Jurassic, southwestern Colorado. This hierarchy is discussed.

  7. A classification scheme for fluvial-aeolian system interaction in desert-margin settings

    NASA Astrophysics Data System (ADS)

    Al-Masrahy, Mohammed A.; Mountney, Nigel P.

    2015-06-01

    This study examines 130 case examples from 60 desert regions to propose a generalised framework to account for the diverse types of interaction known to exist between active aeolian and fluvial depositional systems at modern dune-field margins. Results demonstrate the significance of aeolian and fluvial system type, orientation of aeolian versus fluvial landforms, distribution of open versus closed interdune corridors, and fluvial flow processes in controlling the distance and type of penetration of fluvial systems into aeolian dune fields. Ten distinct types of fluvial-aeolian interaction are recognised: fluvial incursions aligned parallel to trend of linear chains of aeolian dune forms; fluvial incursions oriented perpendicular trend of aeolian dunes; bifurcation of fluvial flow between isolated aeolian dune forms; through-going fluvial channel networks that cross entire aeolian dune fields; flooding of dune fields due to regionally elevated water-table levels associated with fluvial floods; fluvial incursions emanating from a single point source into dune fields; incursions emanating from multiple sheet sources; cessation of the encroachment of entire aeolian dune fields by fluvial systems; termination of fluvial channel networks in aeolian dune fields; long-lived versus short-lived modes of fluvial incursion. Quantitative relationships describing spatial rates of change of desert-margin landforms are presented. The physical boundaries between geomorphic systems are dynamic: assemblages of surface landforms may change gradationally or abruptly over short spatial and temporal scales. Generalised models for the classification of types of interaction have application to the interpretation of ancient preserved successions, especially those known only from the subsurface.

  8. Fluvial channels on Titan: Initial Cassini RADAR observations

    Microsoft Academic Search

    Ralph D. Lorenz; Rosaly M. Lopes; Flora Paganelli; Jonathan I. Lunine; Randolph L. Kirk; Karl L. Mitchell; Lawrence A. Soderblom; Ellen R. Stofan; Gian Ori; Melissa Myers; Hideyaki Miyamoto; Jani Radebaugh; Bryan Stiles; Stephen D. Wall; C. A. Wood

    2008-01-01

    Cassini radar images show a variety of fluvial channels on Titan's surface, often several hundreds of kilometers in length. Some (predominantly at low- and mid-latitude) are radar-bright and braided, resembling desert washes where fines have been removed by energetic surface liquid flow, presumably from methane rainstorms. Others (predominantly at high latitudes) are radar-dark and meandering and drain into or connect

  9. Taphonomy of plants in a paratropical fluvial system

    SciTech Connect

    Burnham, R.J.

    1986-05-01

    Investigation of the subenvironments of a modern paratropical fluvial system in southern Mexico indicates that certain depositional settings are relatively accurate in representing the local flora. Epiphytes, lianas, and those woody plants that are a small fraction of the standing biomass occur in sediments in approximate proportion to their representation (number of individuals) in the vegetation. A paleoenvironmental reconstruction of the flood plain as a whole can be made from the plants preserved when all subenvironments provide conditions for fossilization and when plant parts from each environment are retrieved in large quantities. However, discrepancies arise in reconstruction from the preservational qualities of distinct subenvironments and from differences in plant species composition among the subenvironments. For example, sites at a channel margin provide ideal preservational potential, but the plants preserved are low in specific diversity relative to the flood-plain forest, reflecting only those plants that live at the edge of the water. Important sedimentologic differences also exist among subenvironments of a fluvial system. A combination of potential plant-macrofossil and sedimentologic indicators can be used to characterize the subenvironments most likely to preserve plants. Ancient fluvial and upper deltaic sediments in Washington state have been investigated for fossil macrofloras and sedimentary structures. Subenvironments have been characterized based on the diversity and taxonomic composition of the preserved floras as well as on sedimentological criteria. The Eocene sediments support the hypothesis that within a fluvial system, dramatic floristic differences exist among subenvironments. Paleoecologic and evolutionary reconstructions can be improved with knowledge of the probable taphonomic biases of each depositional site.

  10. 7. Photocopy of map of the Agua Fria Valley and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Photocopy of map of the Agua Fria Valley and lands to be irrigated by the Agua Fria Water and Land Company. Photographer Mark Durben, 1987 Source: 'Map of the Agua Fria Valley and the Western Portion of the Salt River Valley Showing the System of Reservoirs and Canals of the Agua Fria Water and Land Company and the Land to be Irrigated Thereby 160,000 Acres of New Land to be Reclaimed in the Maricopa County, Arizona Territory,' (Brochure) Union Photo Engraving Company, c. 1895, Salt River Project Research Archives, Tempe, Arizona. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  11. Listeria monocytogenes aguA1, but Not aguA2, Encodes a Functional Agmatine Deiminase

    PubMed Central

    Cheng, Changyong; Chen, Jianshun; Fang, Chun; Xia, Ye; Shan, Ying; Liu, Yuan; Wen, Guilan; Song, Houhui; Fang, Weihuan

    2013-01-01

    Listeria monocytogenes is adaptable to low pH environments and therefore crosses the intestinal barrier to establish systemic infections. L. monocytogenes aguA1 and aguA2 encode putative agmatine deiminases (AgDIs) AguA1 and AguA2. Transcription of aguA1 and aguA2 was significantly induced at pH 5.0. Deletion of aguA1 significantly impaired its survival both in gastric fluid at pH 2.5 and in mouse stomach, whereas aguA2 deletion did not show significant defect of survival in gastric fluid. With agmatine as the sole substrate, AguA1 expressed in Escherichia coli was optimal at 25 °C and over a wide range of pH from 3.5 to 10.5. Recombinant AguA2 showed no deiminase activity. Site-directed mutagenesis revealed that all nine AguA1 mutants completely lost enzymatic activity. AguA2 acquired AgDI activity only when Cys-157 was mutated to glycine. AguA1 mutation at the same site, G157C, also inactivated the enzyme. Thus, we have discovered Gly-157 as a novel residue other than the known catalytic triad (Cys-His-Glu/Asp) in L. monocytogenes that is critical for enzyme activity. Of the two putative AgDIs, we conclude that only AguA1 functionally participates in the AgDI pathway and mediates acid tolerance in L. monocytogenes. PMID:23918931

  12. New Mesoscale Fluvial Landscapes - Seismic Geomorphology and Exploration

    NASA Technical Reports Server (NTRS)

    Wilkinson, M. J.

    2013-01-01

    Megafans (100-600 km radius) are very large alluvial fans that cover significant areas on most continents, the surprising finding of recent global surveys. The number of such fans and patterns of sedimentation on them provides new mesoscale architectures that can now be applied on continental fluvial depositional systems, and therefore on. Megafan-scale reconstructions underground as yet have not been attempted. Seismic surveys offer new possibilities in identifying the following prospective situations at potentially unsuspected locations: (i) sand concentrations points, (ii) sand-mud continuums at the mesoscale, (iii) paleo-valley forms in these generally unvalleyed landscapes, (iv) stratigraphic traps, and (v) structural traps.

  13. Large Fluvial Fans: Aspects of the Attribute Array

    NASA Technical Reports Server (NTRS)

    Wilkinson, Justin M.

    2015-01-01

    In arguing for a strict definition of the alluvial fan (coarse-grained with radii less than10 km, in mountain-front settings), Blair and McPherson (1994) proposed that there is no meaningful difference between large fluvial fans (LFF) and floodplains, because the building blocks of both are channel-levee-overbank deposits. Sediment bodies at the LFF scale (greater than 100 km long, fan-shaped in planform), are relatively unstudied although greater than 160 are now identified globally. The following perspectives suggest that the significance of LFF needs to be reconsidered.

  14. Mid-late Holocene environments of Agua Buena locality (34°50'S 69°56'W), Mendoza, Argentina

    NASA Astrophysics Data System (ADS)

    Navarro, Diego; Mehl, A.; Zarate, M. A.; Paez, M. M.

    2010-03-01

    In southern South America the acquisition of high-quality Holocene paleoclimate data is a priority due to the paucity of complete, continuous and well dated records. Here we report preliminary results from a combined sedimentological and palynological study of an alluvial fan sequence and the laterally connected sedimentary deposits of the Vega de la Cueva profile at Agua Buena east of the Andes in central Argentina. The main geomorphological units of the area were identified and mapped based on satellite image analysis and multiple field surveys. The sedimentological and pollen results allowed us to reconstruct the development of some environments. The Agua Buena record corresponds to the distal facies of the Arroyo Bayo alluvial fan starting the aggradation process prior to ca. 4100 cal yr BP. The organic-rich levels found were formed during the development of wetlands (vegas) dominated by Cyperaceae, Juncaceae and Poaceae. These highly productive environments with almost permanent water saturation were important between 4100 and 2800 cal yr BP, indicating more stable conditions. After 2800 cal yr BP, the organic content was comparatively lower with increasing sedimentation rates that are indicative of higher fluvial discharges. This information is fundamental to interpret both the pollen and charcoal records of the area and to evaluate their representativeness and potential to reconstruct past local and/or regional vegetation.

  15. Optimality approaches to describe characteristic fluvial patterns on landscapes

    PubMed Central

    Paik, Kyungrock; Kumar, Praveen

    2010-01-01

    Mother Nature has left amazingly regular geomorphic patterns on the Earth's surface. These patterns are often explained as having arisen as a result of some optimal behaviour of natural processes. However, there is little agreement on what is being optimized. As a result, a number of alternatives have been proposed, often with little a priori justification with the argument that successful predictions will lend a posteriori support to the hypothesized optimality principle. Given that maximum entropy production is an optimality principle attempting to predict the microscopic behaviour from a macroscopic characterization, this paper provides a review of similar approaches with the goal of providing a comparison and contrast between them to enable synthesis. While assumptions of optimal behaviour approach a system from a macroscopic viewpoint, process-based formulations attempt to resolve the mechanistic details whose interactions lead to the system level functions. Using observed optimality trends may help simplify problem formulation at appropriate levels of scale of interest. However, for such an approach to be successful, we suggest that optimality approaches should be formulated at a broader level of environmental systems' viewpoint, i.e. incorporating the dynamic nature of environmental variables and complex feedback mechanisms between fluvial and non-fluvial processes. PMID:20368257

  16. Fluvial biogeomorphology in the Anthropocene: Managing rivers and managing landscapes.

    NASA Astrophysics Data System (ADS)

    Viles, Heather

    2015-04-01

    Biogeomorphology considers the many, and often complex, interactions between ecological and geomorphological processes. The concept of the Anthropocene deserves greater attention by scientists working on biogeomorphology, as will be demonstrated in this talk though a focus on fluvial environments. Rivers and river systems have been the subject of long-term human interference and management across the world, often in the form of direct manipulation of biogeomorphic interactions. Up to the present three broadly-defined phases of the Anthropocene can be identified - the Palaeoanthropocene, the Industrial Revolution and the Great Acceleration. Each of these broad phases of the Anthropocene has different implications for fluvial biogeomorphology and river management. The nature and dynamics of tufa-depositing systems provide good examples of the differing Anthropocene situations and will be focused on in this talk. We may now be entering a fourth phase of the Anthropocene called 'Earth system stewardship'. In terms of better understanding and managing the biogeomorphic interactions within rivers in such a phase, an improved conceptualisation of the Anthropocene and the complex web of interactions between human, ecological and geomorphological processes is needed.

  17. Fluvial sediment fingerprinting: literature review and annotated bibliography

    USGS Publications Warehouse

    Williamson, Joyce E.; Haj, Adel E., Jr.; Stamm, John F.; Valder, Joshua F.; Prautzch, Vicki L.

    2014-01-01

    The U.S. Geological Survey has evaluated and adopted various field methods for collecting real-time sediment and nutrient data. These methods have proven to be valuable representations of sediment and nutrient concentrations and loads but are not able to accurately identify specific source areas. Recently, more advanced data collection and analysis techniques have been evaluated that show promise in identifying specific source areas. Application of field methods could include studies of sources of fluvial sediment, otherwise referred to as sediment “fingerprinting.” The identification of sediment is important, in part, because knowing the primary sediment source areas in watersheds ensures that best management practices are incorporated in areas that maximize reductions in sediment loadings. This report provides a literature review and annotated bibliography of existing methodologies applied in the field of fluvial sediment fingerprinting. This literature review provides a bibliography of publications where sediment fingerprinting methods have been used; however, this report is not assumed to provide an exhaustive listing. Selected publications were categorized by methodology with some additional summary information. The information contained in the summary may help researchers select methods better suited to their particular study or study area, and identify methods in need of more testing and application.

  18. Notes: Retention of Adaptive Rheotactic Behavior by F1 Fluvial Arctic Grayling

    Microsoft Academic Search

    Calvin M. Kaya; Eric D. Jeanes

    1995-01-01

    Downstream movements of age-0 Arctic grayling Thymallus arcticus from an indigenous fluvial population (Big Hole River) and two inlet-spawning, lacustrine populations (Upper Red Rock Lake and Ennis Reservoir) were compared in a natural stream. All fish were incubated and reared together in a hatchery and acclimated together in the stream before being released in the stream. All fluvial test fish

  19. RAPID COMMUNICATION \\/ COMMUNICATION RAPIDE A new method to identify the fluvial regimes used by spawning salmonids

    Microsoft Academic Search

    Hamish J. Moir; Christopher N. Gibbins; John M. Buffington; John H. Webb; Chris Soulsby; Mark J. Brewer

    Basin physiography and fluvial processes structure the availability of salmonid spawning habitat in river net- works. However, methods that allow us to explicitly link hydrologic and geomorphic processes to spatial patterns of spawning at scales relevant to management are limited. Here we present a method that can be used to link the abundance of spawning salmonids to fluvial processes at

  20. Transient fluvial incision in the headwaters of the Yellow River, northeastern Tibet, China

    E-print Network

    Heimsath, Arjun M.

    Transient fluvial incision in the headwaters of the Yellow River, northeastern Tibet, China Nathan of this wave of transient incision is marked by a series of knickpoints that are found at nearly the same. Robinson, and U. Reiser (2007), Transient fluvial incision in the headwaters of the Yellow River

  1. Fluvial features on Titan: Insights from morphology and modeling Devon M. Burr1,

    E-print Network

    Wang, Xiaorui "Ray"

    Fluvial features on Titan: Insights from morphology and modeling Devon M. Burr1, , J. Taylor Perron, Tucson, Arizona 85721-0011, USA ABSTRACT Fluvial features on Titan have been iden- tified in synthetic aperture radar (SAR) data taken during spacecraft flybys by the Cassini Titan Radar Mapper (RADAR

  2. Riparian shrub metal concentrations and growth in amended fluvial mine tailings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fluvial mine tailing deposition has caused extensive riparian damage throughout the western United States. Willows are often used for fluvial mine tailing revegetation, but some species accumulate excessive metal concentrations which could be detrimental to browsers. In a greenhouse experiment, gr...

  3. Periglacial fluvial systems in northwest Europe during marine isotope stages 4 and 3

    Microsoft Academic Search

    P. L. Gibbard; R. M. Briant

    2001-01-01

    Comparison of fluvial successions in river valleys dating from marine isotope (MI) Stages 4 and 3 in a west–east transect from Britain to Poland shows the spatial and temporal variation in palaeohydrological characteristics of northwest European river valleys during these stages. MI Stage 4 has been a period of deep fluvial incision. Following this erosion, most valleys were filled during

  4. Modeling fluvial erosion on regional to continental scales

    NASA Technical Reports Server (NTRS)

    Howard, Alan D.; Dietrich, William E.; Seidl, Michele A.

    1994-01-01

    The fluvial system is a major concern in modeling landform evolution in response to tectonic deformation. Three stream bed types (bedrock, coarse-bed alluvial, and fine-bed alluvial) differ in factors controlling their occurrence and evolution and in appropriate modeling approaches. Spatial and temporal transitions among bed types occur in response to changes in sediment characteristics and tectonic deformation. Erosion in bedrock channels depends upon the ability to scour or pluck bed material; this detachment capacity is often a power function of drainage area and gradient. Exposure of bedrock in channel beds, due to rapid downcutting or resistant rock, slows the response of headwater catchments to downstream baselevel changes. Sediment routing through alluvial channels must account for supply from slope erosion, transport rates, abrasion, and sorting. In regional landform modeling, implicit rate laws must be developed for sediment production from erosion of sub-grid-scale slopes and small channels.

  5. Dynamic Flocculation of Muds in Fluvial to Marine Transitions

    NASA Astrophysics Data System (ADS)

    Keyvani, A.; Strom, K. B.

    2012-12-01

    Rivers are the primary conduits for delivery of sediment and organic matter to the sea. The sediments from river plumes may deposit and be preserved in estuarine and deltaic zones, or may be carried and mixed by ocean currents to deposit elsewhere on the shelf or basin. The sediment settling velocity is the most important parameter in terms of controlling and predicting depositional patterns in river mouths and coastal shelves. Settling velocity greatly impacts the distribution of muds in deltas and turbidity currents, and is largely controlled by grain size and density. The flocculation process yields mud aggregates of variable size and density as a function of turbulent energy and salt levels. Since turbulent energy and salinity both change during the fluvial to marine transition, dynamic flocculation processes may have a significant control to the eventual distribution of sediment through these zones. The purpose of this study is to quantify the evolution of floc size distribution and fractal dimension of suspended flocs with time as a function of time and space as turbulent shear and salinity levels vary in the fluvial to marine transition (river jet/plume and turbidity currents). To do this, experiments are carried out in a laboratory chamber where turbulent shear and salinity levels are varied to mimic a fixed volume of fluid being advected through the transition zone, and floc size distribution properties are measured within the mixing chamber using a specially designed floc imaging system and a set of image processing routines that allows us to measure floc size distributions of suspended flocs. Results demonstrate that floc properties and floc settling velocity change due to the dynamic flocculation and are dependent on the turbulent time history the mud suspension was exposed to under constant concentration. Results from the study are then used to frame a discussion on the relative importance of accounting for these dynamic effects in numerical models of deltas and turbidity currents.

  6. The chemistry of fluvial sediments analyzed by the Curiosity rover

    NASA Astrophysics Data System (ADS)

    Mangold, Nicolas; Thompson, Lucy; Le Deit, Laetitia; Forni, Olivier; Gellert, Ralf; Grotzinger, John; Maurice, Sylvestre; Wiens, Roger

    2015-04-01

    The Curiosity rover has encountered a diversity of sedimentary rocks, which overall have displayed significant variations in both texture and composition. Early observations by the Curiosity rover in Gale crater revealed isolated outcrops of cemented pebbles and sand grains with textures typical of fluvial sedimentary conglomerates (Williams et al., Science, 2013). Sandstones and mudstones, interpreted as having been deposited in a fluvio-lacustrine environment, were observed at Yellowknife Bay, a location identified from orbital images as of significant interest (Grotzinger et al., 2014). More stratified sandstones have been observed in the second and third terrestrial years of investigation in the outcrops named Cooperstown, Kylie and Kimberley, and Pahrump. The different groups of sediments have been interpreted to represent fluvial transport across Gale crater (Grotzinger et al., AGU, 2014), but they show a high variation in their composition, especially at Kimberley where rocks display enhanced K proportion. Among sedimentary rocks, conglomerates provide the most direct knowledge of the source of sediments. Conglomerates observed by Curiosity contain clasts with a strong diversity in albedo and textures indicating multiple sources on the Gale crater rims, with local identification of minerals such as plagioclases and alkali feldspars. Assuming the conglomerates are a mechanically altered product of crustal rocks with relatively little aqueous alteration, the average composition of conglomerates can be considered as a proxy for the source rock composition. This average composition displays a more felsic composition than the Martian average crust as defined by meteorites and orbital data implying that the Gale crater rim is enriched in felsic rocks. The difference in sedimentary composition suggests a variability in source rocks and/or diagenetic evolution compared to the conglomerates that needs to be considered in the broad context of Gale crater's evolution.

  7. Towards a phoenix phase in aeolian research: shifting geophysical perspectives from fluvial dominance

    SciTech Connect

    Whicker, Jeffrey J [Los Alamos National Laboratory; Field, Jason P [UNIV OF ARIZONA; Breshears, David D [UNIV OF ARIZONA

    2008-01-01

    Aeolian processes are a fundamental driver of earth surface dynamics, yet the importance of aeolian processes in a broader geosciences context may be overshadowed by an unbalanced emphasis on fluvial processes. Here we wish to highlight that aeolian and fluvial processes need to be considered in concert relative to total erosion and to potential interactions, that relative dominance and sensitivity to disturbance vary with mean annual precipitation, and that there are important scale-dependencies associated with aeolian-fluvial interactions. We build on previous literature to present relevant conceptual syntheses highlighting these issues. We then highlight the relative investments that have been made in aeolian research on dust emission and management relative to that in fluvial research on sediment production. Literature searches highlight that aeolian processes are greatly understudied relative to fluvial processes when considering total erosion in different environmental settings. Notably, within the USA, aeolian research was triggered by the Dust Bowl catastrophe of the 1930s, but the resultant research agencies have shifted to almost completely focusing on fluvial processes, based on number of remaining research stations and on monetary investments in control measures. However, numerous research issues associated with intensification of land use and climate change impacts require a rapid ramping up in aeolian research that improves information about aeolian processes relative to fluvial processes, which could herald a post-Dust Bowl Phoenix phase in which aeolian processes are recognized as broadly critical to geo- and environmental sciences.

  8. Lahar hazards at Agua volcano, Guatemala

    USGS Publications Warehouse

    Schilling, S.P.; Vallance, J.W.; Matías, O.; Howell, M.M.

    2001-01-01

    At 3760 m, Agua volcano towers more than 3500 m above the Pacific coastal plain to the south and 2000 m above the Guatemalan highlands to the north. The volcano is within 5 to 10 kilometers (km) of Antigua, Guatemala and several other large towns situated on its northern apron. These towns have a combined population of nearly 100,000. It is within about 20 km of Escuintla (population, ca. 100,000) to the south. Though the volcano has not been active in historical time, or about the last 500 years, it has the potential to produce debris flows (watery flows of mud, rock, and debris—also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

  9. Constraining the average fill densities of Mars' lowlands and fluvial erosion of Titan's polar regions.

    E-print Network

    Tewelde, Yodit

    2013-01-01

    Other than Earth, Mars and Titan are the only bodies in our Solar System where we have observed widespread fluvial activity. In this thesis I present two approaches for constraining the extent of multiple resurfacing ...

  10. A mass-balance framework for quantifying downstream changes in fluvial architecture

    E-print Network

    Paola, Chris

    A mass-balance framework for quantifying downstream changes in fluvial architecture NIKKI STRONG measured sections into this `mass balance' coordinate system removes much, although not all- balance effects via transformation to fraction deposited reveals more clearly those residual architectural

  11. Stratigraphy and facies architecture of the fluvial aeolian lacustrine Sergi Formation (Upper Jurassic), Recôncavo Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Scherer, Claiton M. S.; Lavina, Ernesto L. C.; Dias Filho, Dorval C.; Oliveira, Flávio M.; Bongiolo, Daniela E.; Aguiar, Eduardo S.

    2007-02-01

    The Sergi Formation encompasses an upper Jurassic fluvial-eolian-lacustrine succession deposited within a wide intracratonic basin. Its sand bodies represent the largest and more important reservoirs in the Recôncavo Basin, hosting 362 million m 3 of oil in place. The main goal of this paper is to provide a detailed stratigraphic analysis of the Sergi Formation based on core and outcrop data. It was achieved through the recognition and correlation of regional surfaces that have allowed the subdivision of this unit into distinct depositional sequences, and the reconstruction of its depositional history. The studied succession can be subdivided into three unconformity-bounded sequences. Sequence I is composed of lacustrine mudstone at its base, which is overlain by fine- to medium-grained sandstone related to aeolian dune and sand sheet and ephemeral fluvial stream deposits. Fluvial strata indicate northeastward-flowing streams whereas aeolian dune deposits suggest the action of southwestward-blowing winds. The regional unconformity bounding sequences I and II denotes both a climate change and tectonic rearrangement of the basin. This surface delineates a change in the depositional style, from fluvial-aeolian-lacustrine (Sequence I) to entirely fluvial (Sequence II). The latter includes coarse-grained to conglomeratic sandstone deposited within northwestward-flowing braided channel-belts. Changes in fluvial palaeocurrent, from sequence I to II, indicate rearrangement of the drainage system related to basin tectonism. Furthermore, a change in the fluvial discharge regime took place as a result of a change from a drier to a wetter climate. Fluvial deposition in Sequence I was related to ephemeral streams whereas fluvial facies architecture of the Sequence II deposits indicates perennial braided streams with significant discharge variation. Another regional unconformity, this time related to a stratigraphic base level fall and consequent widespread, basinwide aeolian deflation, separates the braided fluvial facies of Sequence II from the fine- to medium-grained sandstones ascribed to sheet-floods, aeolian dunes and aeolian sand sheets of Sequence III. The resumption of aeolian sedimentation indicates a return to drier conditions in the basin. The abrupt change from fluvial-aeolian deposits to the lacustrine deposits of the overlying Itaparica Formation suggest a rapid rise of the water table and consequent basinwide flooding.

  12. Analysis of Ancient Fluvial Patterns on the Surface of Mars

    NASA Technical Reports Server (NTRS)

    Jethani, Henna; Williams, M. E.

    2010-01-01

    This project involves the study of ancient fluvial patterns on the surface of Mars, including raised curvilinear features (RCFs) and negative relief channels. It requires the use of geological images provided by the Mars Reconnaissance Orbiter to determine how water shaped the surface of Mars in the form of rivers, lakes and/or oceans approximately 3.5 billion years ago, during the Noachian period. The role of the intern is to examine the images and record the corresponding measurements of ancient river systems in an Excel spreadsheet to assist in determining the Noachian water cycle on Mars. Resources used to make these measurements include the Arena software, hand-drawn sketch maps, Microsoft Word, Microsoft Excel and the images provided by the Mars Reconnaissance Orbiter. The Context Imager (CTX) returns black and white images at a resolution of six meters per pixel. The camera can take images with a width of 30 km and a length of 160 km. Seventeen images were observed in total. Images are analyzed and notes are taken concerning their terminal deposits, stream ordering and drainage pattern. The Arena software is utilized to make the images more visible by allowing control of contrast and magnification. Once the image is adjusted, measurements: length, average width, drainage basin area, sinuous ridge area are recorded, at a magnification of one, through using the line segment and polygon tools. After an image has been analyzed and measured, a sketch map is drawn in order to clearly identify the various segments, basins and terminal deposits the intern observed. Observations are used to further classify the fluvial patterns; their drainage pattern is defined as dendritic, parallel, trellis, rectangular, radial, centripetal, deranged or discordant. Once observational notes are completed, mathematical relations are used to determine drainage density, stream frequency, theoretic basin area and sinuosity index. These data will be added to a larger data set that will yield a comprehensive view of early Mars drainage systems. The data obtained from the work conducted will be used to characterize the nature and behavior of water on the surface of Mars. Thorough understanding of the Martian water cycle will serve as biologically significant information. Through working on this project, I acquired insight into the study of planet Mars, and skills in the Arena software as well as the organization of a vast amount of data.

  13. Fluvial entrainment of low density peat blocks (block carbon)

    NASA Astrophysics Data System (ADS)

    Warburton, Jeff

    2014-05-01

    In many fluvial environments low density materials are transported in significant quantities and these form an important part of the stream load and /or have a distinct impact on sedimentation in these environments. However, there are significant gaps in understanding of how these materials are entrained and transported by streams and rivers. Eroding upland peatland environments in particular, frequently have fluvial systems in which large eroded peat blocks, often exceeding 1 m in length; form an important component of the stream material flux. Transport of this material is significant in determining rates of erosion but also has important impacts in terms of damage to infrastructure and carbon loss. This paper describes a field experiment designed to establish for the first time the conditions under which large peat blocks (c. > 0.1 m b axis) are initially entrained from a rough gravel bed. The field site is Trout Beck, in the North Pennines, Northern England which is an upland wandering river channel with occasional lateral and mid channel bars. Mean low flow stage is typically 0.2 m but during flood can rapidly rise, in one to two hours, to over 1.5 m. To study peat block entrainment a bespoke data acquisition system consisting of two pressure transducers, four release triggers and time lapse camera was set up. The pressure transducers provided a record of local depth and the release triggers were embedded in peat blocks to record initial motion and arranged on the rough stream bed. The time lapse camera provided verification of timing of block entrainment (during daylight hours) and also provided information on the mechanism of initial movement. Peat blocks were cut from a local source and were equidimensional, ranging in size from 0.1 to 0.7 m. The derived entrainment function is related to a critical depth of entrainment. Results demonstrate that peat blocks are entrained when the local depth approximates the height of the peat block. Blocks frequently shift position prior to entrainment but once entrained are rapidly transported downstream. Because of the rough stream bed local depth, measured on the four sides of the block varies markedly and needs to be considered in developing an appropriate entrainment function and; is useful in explaining initial movement prior to entrainment. In some experiments a small accelerometer (HOBO Pendant G data logger) was used to investigate transport dynamics following entrainment. Further work will seek to improve the entrainment function by extending the size range of tests, developing a shear stress related function and investigating the importance of block shape (rounding) on entrainment.

  14. Optical stimulated Luminescence Signal on Modern Fluvial Deposit in Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Y. G.; Wu, T. S.; Chen, Y. W.; Kuo, Y. T.

    2014-12-01

    The river terraces overlain by fluvial and debris-flow deposit are widely distributed in Taiwan due to its active tectonic situation. They are not only critical in reconstructing the river evolution, but also of importance in understanding neotectonics. However, the age estimation for the terraces has their own problems by C-14 as well as OSL (Optical Stimulated Luminescence) dating method. For C-14 method, the major problem is the difficulty in discovering the suitable samples, but for OSL method the zeroing effect of the sediments becomes the major barrier if quartz SAR (Single Aliquot Regenerative) procedure is applied. In order to test the residual dose from different drainage areas in Taiwan, modern deposits were collected from 13 main rivers and 3 samples for each from upper-stream to downstream. The apparent dose of modern fluvial deposit was defined as residual dose and believed to be able to give a hint for estimating the zeroing effect for river terraces. Quartz SAR OSL procedure on small aliquot was adopted for all samples in this study. Our results show the residual dose in western Taiwan strongly relies on the source from. If we further apply the mean value of smallest 5% on samples from modern debris flow deposits in upper-stream, the residual dose rise up as high as ~40Gy but lower down to ~15Gy for samples collected from river mouth estuary. It implies that there will be a large error when evaluating the age of debris deposit terrace by quartz SAR OSL procedure. However, if the modern river does not suffer from debris flow in upper-stream, the residual dose is ~5Gy in upper stream and only -0.7~2Gy to the lower steam estuary, which provide better chance to derive relatively reliable ages. We also find that the luminescence characteristics is different between the samples in western and eastern Taiwan respectively. The quartz grains from eastern Taiwan are much dimer than those of the western Taiwan. We may therefore face severe challenge to approach a reliable age for a river terrace located in eastern Taiwan.

  15. Late Cenozoic fluvial development within the Sea of Azov and Black Sea coastal plains

    NASA Astrophysics Data System (ADS)

    Matoshko, A.; Gozhik, P.; Semenenko, V.

    2009-09-01

    Late Cenozoic terrestrial deposits are widespread across the northern coastal regions of the Black Sea and the Sea of Azov and represent diverse fluvial, estuarine and deltaic environments. The dating and correlation of these deposits rely on stratigraphically-associated marine index beds, mammalian and molluscan faunas and magnetostratigraphy. In detail the geometries of these sediment bodies are extremely complex, typically varying between localities and representing many cycles of incision and aggradation. However, the overall disposition of the sediments reflects the transition from the uplifting sediment source region to the north and the subsiding depocentre in the interior of the Black Sea to the south. Since the Middle Miocene the area of the Paratethys/Black Sea depocentre has decreased significantly, but since the Middle Pliocene the hinge zone between uplift and subsidence has been located close to the modern coastline. A combination of regional and local differential crustal movements has given rise to the great variety of fluvial sediment bodies, to the erosion-aggradation cycles, different phases and river activity and to the various fluvial landforms that have all been important in landscape development in this region during the past 12 Ma. The fluvial erosion-accumulation cycles (during the upper Serravillian-Messinian, the Zanclean-late Gelasian, and the Pleistocene) and corresponding cycles of relief dissection and planation are reconstructed against a background of local sea-level changes and climatic variations determined from palaeobotanical data. The maximum fluvial incision occurred in the early Zanclean time with alluvial coastal plains, unique in this area, developing in the Gelasian. Increased climatic aridity during the Pleistocene caused a reduction of fluvial activity in comparison with the Late Miocene and Pliocene. The sea-level oscillations and Pleistocene glaciations affected fluvial processes in different ways. The most remarkable events were the substantial reduction of fluvial activity during the Messinian dessication in the Black Sea and drainage of the shelf, with intensive dissection, coeval with the Last Glaciation.

  16. Equations and their physical interpretation in numerical modeling of heavy metals in fluvial rivers

    Microsoft Academic Search

    SuiLiang Huang

    2010-01-01

    Based on the previous work on the transport-transformation of heavy metal pollutants in fluvial rivers, this paper presented\\u000a the formulation of a two-dimensional model to describe heavy metal transport-transformation in fluvial rivers by considering\\u000a basic principles of environmental chemistry, hydraulics, mechanics of sediment transport and recent developments along with\\u000a three very simplified test cases. The model consists of water flow

  17. A Record of Fluvial Response for the Australian Wet Tropics and Relationships to Regional Climate Change

    NASA Astrophysics Data System (ADS)

    Hughes, K. E.; Croke, J.; Bartley, R.; Thompson, C.

    2014-12-01

    The reconstruction of fluvial dynamics from alluvial sedimentary sequences has contributed to our understanding of the link between global Quaternary climate change and landscape response. However, the geographical bias in such studies towards middle and higher latitudes leaves a gap in our understanding of climate change and landscape evolution in the tropics. The Wet Tropics biogeographic region in the tectonically-stable northeast Australia provides an ideal setting to study the history of fluvial response: catchments are small and steep; receive high annual rainfall; and cyclones are common which collectively, promotes short catchment response times. Additionally, the region benefits from an extensive range of paleoclimate reconstructions based on pollen, coral and speleothem proxies. The aim of this field-based research is to establish the nature of the relationship between fluvial response and Quaternary climate change in the Australian Wet Tropics region. To construct a temporal record of fluvial response, forty sediment cores (4-12m in length) were extracted from floodplains and terraces in similar geomorphic settings across five catchments. The stratigraphy of each core was described and 40 samples from select cores dated using optically stimulated luminescence. This temporal record of landscape response was then compared to the regional climate record to examine the relationship between fluvial response and tropical climate change. This work provides the first systematic study of fluvial sedimentary records in the Wet Tropics and in doing so makes valuable contribution to understanding of landscape evolution in the tropics.

  18. Fluvial Placement of Radioactive Contaminants a Weldon Spring Case Study

    SciTech Connect

    Meier, J.

    2002-02-26

    The operation of the Weldon Spring Uranium Feed Materials Plant in St. Charles, MO between 1958 and 1966 resulted in the migration and emplacement of radioactive contaminants into surface water drainage systems. Multiple drainage systems, receiving from a variety of waste discharge points, combined to create unique and unexpected depositional environment. Discovery and investigation of the depositional environments was a significant technical challenge due to the complex nature of sediment movement and emplacement. The objective of this investigation was to show that application of the knowledge of geomorphic processes is an essential element of a complete stream characterization, pursuant to risk analysis and remediation. This paper sets out to describe many of the expected and unexpected findings of the investigations by the Weldon Spring Site Remedial Action Project (WSSRAP) into the placement and rework of contaminated sediments in stream systems. Information from this paper will be useful to other agencies and contractor personnel faced with the challenge of locating and quantifying contaminated sediments in seemingly haphazard fluvial depositional conditions.

  19. Microbiological and Geochemical Characterization of Fluvially Deposited Sulfidic Mine Tailings

    PubMed Central

    Wielinga, Bruce; Lucy, Juliette K.; Moore, Johnnie N.; Seastone, October F.; Gannon, James E.

    1999-01-01

    The fluvial deposition of mine tailings generated from historic mining operations near Butte, Montana, has resulted in substantial surface and shallow groundwater contamination along Silver Bow Creek. Biogeochemical processes in the sediment and underlying hyporheic zone were studied in an attempt to characterize interactions consequential to heavy-metal contamination of shallow groundwater. Sediment cores were extracted and fractionated based on sediment stratification. Subsamples of each fraction were assayed for culturable heterotrophic microbiota, specific microbial guilds involved in metal redox transformations, and both aqueous- and solid-phase geochemistry. Populations of cultivable Fe(III)-reducing bacteria were most prominent in the anoxic, circumneutral pH regions associated with a ferricrete layer or in an oxic zone high in organic carbon and soluble iron. Sulfur- and iron-oxidizing bacteria were distributed in discrete zones throughout the tailings and were often recovered from sections at and below the anoxic groundwater interface. Sulfate-reducing bacteria were also widely distributed in the cores and often occurred in zones overlapping iron and sulfur oxidizers. Sulfate-reducing bacteria were consistently recovered from oxic zones that contained high concentrations of metals in the oxidizable fraction. Altogether, these results suggest a highly varied and complex microbial ecology within a very heterogeneous geochemical environment. Such physical and biological heterogeneity has often been overlooked when remediation strategies for metal contaminated environments are formulated. PMID:10103249

  20. Fluvial sedimentation following Quaternary eruptions of Mount St. Helens, Washington

    SciTech Connect

    Janda, R.J.; Meyer, D.F

    1985-01-01

    Depositional records of convulsive volcanic events at Mount St. Helens are in many places obscured by rapid fluvial erosion and deposition close to the volcano. Some major eruptions are recorded primarily by lahars and alluvium deposited tens of kilometers away. About 35 percent of the distinctive hummocky topography of the 1980 North Fork Toutle debris avalanche deposit now resembles an alluvial fan or a braided glacial outwash plain covered with 10 m or more of alluvium. Deposits of small (20 x 10/sup 6/m/sup 3/) but damaging lahars, such as those generated in the afternoon of 18 May 1980 and on 19 March 1982, have been largely eroded away. Rivers draining rapidly eroding areas surrounding Mount St. Helens presently have sediment yields that are among the highest in the world for nonglaciated streams of comparable size. These sediment loads are capable of causing aggradation-induced flooding in populated areas along the lower Toutle and Cowlitz Rivers. Sediment retention structures and dredging have prevented such flooding. Immediately following prehistoric eruptions, however, coarse-grained volcanic alluvium was deposited in the Cowlitz River to levels more than 1 m above the 1980 mud flow inundation level. Post-1980 rapid landscape modifications and high sediment yields are noteworthy because the eruption-impact area has not yet had a major regional storm and potentially catastrophic breachings of avalanche-impounded lakes have been prevented through engineering measures.

  1. Fluvial organic carbon losses from a Bornean blackwater river

    NASA Astrophysics Data System (ADS)

    Moore, S.; Gauci, V.; Evans, C. D.; Page, S. E.

    2011-04-01

    Concentrations of dissolved organic carbon (DOC) and particulate organic carbon (POC) were analysed from the source to the mouth of the River Sebangau in Central Kalimantan, Indonesia during the dry and wet seasons in 2008/2009 and an annual total organic carbon (TOC) flux estimated. DOC concentrations were higher and POC concentrations lower in the wet season compared to the dry season. As seen in other tropical blackwater rivers, DOC concentration is consistently around 10 times greater than POC concentration. We estimate the annual TOC flux discharged to the Java Sea to be 0.46 Tg year-1 comprising of 93% (0.43 Tg) DOC and 7% (0.03 Tg) POC. This equates to a fluvial TOC loss flux per unit area over the entire Sebangau catchment of 88 g C m-2 yr-1. When extrapolating the River Sebangau DOC loss flux (83 g C m-2 yr-1) to the peat covered area of Indonesia (206 950 km2), we estimate a DOC loss of 17.2 Tg C yr-1 or ~10% of current estimates of the global annual riverine DOC discharge into the ocean.

  2. Fluvial organic carbon losses from a Bornean blackwater river

    NASA Astrophysics Data System (ADS)

    Moore, S.; Gauci, V.; Page, S.; Evans, C.; Limin, S.

    2010-12-01

    The transport of carbon from terrestrial ecosystems such as peatlands into rivers and out to the oceans plays an important role in the carbon cycle because it provides a link between the terrestrial and marine carbon cycles. Concentrations of dissolved organic carbon (DOC) and particulate organic carbon (POC) were analysed from the source to the mouth of the River Sebangau in Central Kalimantan, Indonesia during the dry and wet seasons in 2008/2009 and an annual total organic carbon (TOC) flux estimated. DOC concentrations were higher and POC concentrations lower in the wet season compared to the dry season. As seen in other tropical blackwater rivers, DOC concentration is consistently around 10 times greater than POC concentration. We estimate the annual TOC flux discharged to the Java Sea to be 0.46 Tg year-1 comprising of 93% (0.43 Tg) DOC and 7% (0.03 Tg) POC. This equates to a fluvial TOC loss flux per unit area over the entire Sebangau catchment of 88g C m-2 yr-1. When extrapolating the Sebangau catchment TOC loss flux (88g C m-2 yr-1) to the peat covered area of Indonesia (206,950 km2), we calculate a TOC loss of 18.2 Tg C yr-1 or ~10% of current estimates of the global annual riverine DOC discharge into the ocean.

  3. Characterization of fluvial sedimentology for reservoir simulation modeling

    SciTech Connect

    Henriquez, A.; Tyler, K.J.; Hurst, A. (Statoil, Stavanger (NO))

    1990-09-01

    This paper presents a critical study of 3D stochastic simulation of a fluvial reservoir and of the transfer of the geological model to a reservoir simulation grid. The stochastic model is conditioned by sand-body thickness and position in wellbores. Geological input parameters-sand-body orientation and width/thickness ratios-are often difficult to determine, and are invariably subject to interpretation. Net/gross ratio (NGR) and sand-body thickness are more easily estimated. Sand-body connectedness varies, depending on the modeling procedure; however, a sedimentary process-related model gives intermediate values for connectedness between the values for a regular packing model and the stochastic model. The geological model is transferred to a reservoir simulation grid by use of transmissibility multipliers and an NGR value for each block. The transfer of data smooths out much of the detailed geological information, and the calculated recovery factors are insensitive to the continuity measured in the geological model. Hence, the authors propose improvements to the interface between geological and reservoir simulation models.

  4. A quantitative vulnerability function for fluvial sediment transport

    NASA Astrophysics Data System (ADS)

    Totschnig, Reinhold; Sedlacek, Walter; Fuchs, Sven

    2010-05-01

    In quantitative risk assessment, risk is expressed as a function of hazard, elements at risk exposed, and the vulnerability. From a natural sciences perspective, vulnerability is defined as the expected degree of loss for an element at risk as a consequence of a certain event. The resulting value is dependent on the impacting process intensity and the susceptibility of the elements at risk, and ranges from 0 (no damage) to 1 (complete destruction). With respect to torrent processes, i.e. fluvial sediment transport, the concept of vulnerability - though widely acknowledged - did not result in any sound quantitative relationship between process intensities and vulnerability values so far, even if considerable loss occurred during recent years. To close this gap and establish this relationship, data from three well-documented torrent events in the Austrian Alps was used to derive a quantitative vulnerability function applicable to residential buildings located on torrent fans. The method applied followed a spatial approach, and was based on process intensities, the spatial characteristics of elements at risk, and average reconstruction values on a local scale. The results suggest a modified Weibull function to fit best to the observed damage pattern if vulnerability is quantified in absolute values, and a modified Frechet function if vulnerability is quantified relatively in relation to the individual building height. The vulnerability relationship obtained is applicable to a mixed type of construction used in European mountain regions, composed from brick masonry and concrete, a typical design in post-1950s building craft in alpine countries.

  5. Fluvial Drainage Basins and Valley Networks: Eastern Margaritifer Sinus, Mars

    NASA Technical Reports Server (NTRS)

    Boothroyd, J. C.; Grant, J. A.

    1985-01-01

    The fluvial drainage of the eastern Margaritifer Sinus (MC-19NE, SE) and northeastern Argyre (MC-26NE) Quadrangles is dominated by two major longitudinal valley networks, the Parana/Loire system on the east, and the Samara Himera system to the west. It is believed that both of these drainages are through-going to the northwest and debouch into Margaritifer Chaos (general location: 12S, 22.5W). The Parana/Loire drainage is bounded on the east in part by an ancient multi-ringed impact basin. The Parana multi-digitate network drains northwest into a depositional basin, and impact basin floor, characterized by positive relief chaos. It is believed that Loire Vallis heads in the basin; thus Parana and Loire Valles may be treated as one system. Samara Valles heads in the northeastern Argyre Quadrangle and extends as a major truck valley to the northwest. Samara Valles cuts through the hills forming one of the concentric rings of the Ladon impact basin and joins the Himera drainage to trend in a more northerly direction to Margaritifer Chaos. The downstream portion of Himera is considered to be part of the Samara

  6. Disturbance of fluvial gravel substrates by signal crayfish (Pacifastacus leniusculus)

    NASA Astrophysics Data System (ADS)

    Johnson, Matthew; Rice, Stephen; Reid, Ian

    2010-05-01

    The reworking of substrates by organisms, termed bioturbation, is considered a fundamental processes in marine and terrestrial environments but has remained relatively unstudied in fluvial environments. This studies looks at the bioturbation of fluvial gravel substrates by signal crayfish, an internationally important invasive species. We investigated the impact of signal crayfish activity in a laboratory flume. Bioturbation by crayfish on both loose arrangements of gravel and water-worked surfaces were studied and two sizes of narrowly-graded gravel were used; 11 - 16 mm and 16 - 22 mm. A laser scanner was used to obtain high resolution digital elevation models (DEMs) of gravel surfaces before and after crayfish activity. These DEMs were used to quantify topographic and structural changes to the surfaces due to the activity of crayfish. It was found that crayfish moved substantial quantities of material from all surfaces within six hours of introduction. The majority of the disturbance was associated with small scale (? 1 median grain diameter) movements of surface grains due to walking and foraging by crayfish. This textural change resulted in a structural alteration to the substrate surface. After six hours of crayfish activity, there was a 14% reduction in the imbrication of the grains from water-worked surfaces. Crayfish also constructed shallow pits and heaped excavated material into a series of mounds around its edge. Crayfish would always posture in pits in the same way. They would fold their vulnerable tails under their body and place their claws in front of their heads. When in pits crayfish predominately orientated themselves so they were facing an upstream direction. This implies that crayfish dig pits in order to streamline their bodies in the flow and lower their protrusion. Although pits and mounds contributed a relatively small proportion to the overall disturbance of substrates, they significantly increased the roughness of substrates. Pit and mound construction was far more prevalent in loose gravel surfaces. This suggests that water-working of gravel substrates not only reduces the vulnerability of grains to entrainment from the flow, but also disturbance by crayfish. Subsequent to topographic analysis, surfaces disturbed by crayfish were entrained in the laboratory flume and compared to control surfaces on which crayfish were not present. Substantially more material was entrained from crayfish disturbed surfaces than control surfaces for both loose and water-worked gravels. In loose 11 - 16 mm gravels, 20% more grains were entrained from surfaces disturbed by crayfish. For water-worked surfaces this increased to 46%. Not only was the increase in entrained material greater for water-worked surfaces but it was also statistically significant. During extended periods of low flow, gravel beds consolidate with the ingress of fine material and grain rearrangement. Both generally increase grain interlock and both increase the stresses required to entrain bed material during the next flood event. This study indicates that crayfish may oppose the process, jostling grains into less stable positions and increasing grain exposure through the mounding of material excavated from pits. Both will affect gravel stability during flood events. This study shows that invasive species may be having detrimental impacts on the physical environment as well as the wider ecological community.

  7. Dynamic LiDAR-NDVI classification of fluvial landscape units

    NASA Astrophysics Data System (ADS)

    Ramírez-Núñez, Carolina; Parrot, Jean-François

    2015-04-01

    The lower basin of the Coatzacoalcos River is a wide floodplain in which, during the wet season, local and major flooding are distinguished. Both types of floods, intermittent and regional, are important in terms of resources; the regional flood sediments enrich the soils of the plains and intermittent floods allow obtaining aquatic resources for subsistence during the heatwave. In the floodplain different abandoned meanders and intermittent streams are quickly colonized by aquatic vegetation. However, from the 1990s, the Coatzacoalcos River floodplain has important topographic changes due to mining, road and bridges construction; erosion and sedimentation requires continuous parcel boundaries along with the increasing demand of channel reparation, embankments, levees and bridges associated to tributaries. NDVI data, LiDAR point cloud and various types of flood simulations taking into account the DTM are used to classify the dynamic landscape units. These units are associated to floods in relation with water resources, agriculture and livestock. In the study area, the first returns of the point cloud allow extracting vegetation strata. The last returns correspond to the bare earth surface, especially in this area with few human settlements. The surface that is not covered by trees or by aquatic vegetation, correspond to crops, pastures and bare soils. The classification is obtained by using the NDVI index coupled with vegetation strata and water bodies. The result shows that 47.96% of the area does not present active vegetation and it includes 31.53% of bare soils. Concerning the active vegetation, pastures, bushes and trees represent respectively 25.59%, 11.14% and 13.25%. The remaining 1.25% is distributed between water bodies with aquatic vegetation, trees and shrubs. Dynamic landscape units' classification represents a tool for monitoring water resources in a fluvial plain. This approach can be also applied to forest management, environmental services and habitat analysis. Thus, the unsupervised LiDAR-NDVI approach coupled with flood simulation developed here, allows studying environmental behavior without introducing subjective considerations.

  8. Sedimentology: general introduction and definitions : fluvial sediment and channel morphology

    USGS Publications Warehouse

    Wolff, Roger G.; Benedict, Paul C.

    1964-01-01

    Sedimentology, the study of sedimentary rocks and the processes by which they are formed, includes and is related to a large number of phenomena. Sedimentology includes the five fundamental processes defined by the term sediaentation --weathering, erosion, transportation, deposition and diagenesis. Sedimentology shares with geomorphology the study of the surface features of the earth. Sedimentology also shares with hydrology the study of river.--channels. River channels are formed in part or in total as a result of flowing water and sediment transport, commonly called the "work of the rivers." This survey of published literature was made to aid in arriving at definitions which would be acceptable to, and representative of, a majority of professional personnel actively engaged in laboratory and field investigations related to the "work of the river." The definitions in this list are intended to explain the terms used in studies of fluvial sediment and channel morphology. No set of definitions can expect universal acceptance, however, i t is hoped that this compilation will be considered a summary and synthesis of present and past usage and that it will serve as a starting point for future usage. Multiple references are cited from textbooks, glossaries and dictionaries, scientific journals and u.s. Government publications. To obtain a mutual understanding and enhance precision, many of the proposed definitions are a composite of those selected from papers or reports covering research studies and field investigations. A draft of this glossary has been reviewed by a group of interested personnel. The results of this review have been carefully considered and the originally-suggested definitions have been revised accordingly, resulting in the present compilation. R. G. Wolff, with the help of Mrs. v. Blatcher, carried out the literature search and compilation of terms and the review results. Paul c. Benedict approved or composed the definitions as presented in this report.

  9. Marine intervals in Neogene fluvial deposits of western Amazonia

    NASA Astrophysics Data System (ADS)

    Boonstra, Melanie; Troelstra, Simon; Lammertsma, Emmy; Hoorn, Carina

    2014-05-01

    Amazonia is one of the most species rich areas on Earth, but this high diversity is not homogeneous over the entire region. Highest mammal and tree-alpha diversity is found in the fluvio-lacustrine Pebas system, a Neogene wetland associated with rapid radiation of species. The estuarine to marine origin of various modern Amazonian fish, plants, and invertebrates has been associated with past marine ingressions into this freshwater Pebas system. The exact nature and age of these invasions is, however, debated. Here we present new evidence from fluvial and fluvio-lacustrine deposits of Neogene age in southeast Colombia, that point to periods of widespread marine conditions in western Amazonia. Our evidence is based on an analysis of marine palynomorphs, such as organic linings of foraminifera and dinoflagellate cysts, present in dark sandy clay sediments that outcrop along the Caqueta and Amazon rivers. Characteristically, the foraminiferal linings can be assigned to three benthic morphotypes only, e.g. Ammonia, Elphidium and Trochammina. This low diversity assemblage is associated with estuarine/marginal marine conditions. No distinct marine elements such as shelf or planktonic species were encountered. The observed foraminiferal linings and dinocyst assemblages are typical for a (eutrophic) shallow marine environment, suggesting that the Pebas freshwater wetland system occasionally changed to (marginal) marine. Although some reworked elements are found, a typical Neogene dinocyst taxon is commonly found supporting in situ deposition. Sedimentological features typical for tidal conditions that are reported for sites in Peru and northeastern Brazil likely relate to these marine ingressions. Sea level changes as well as foreland basin development related to Andes formation may have facilitated the entry of marine water during the Neogene.

  10. Practical Enhancement of Terrestrial Laser Scanning for Fluvial Geomorphology Surveys

    NASA Astrophysics Data System (ADS)

    Hwang, K.; Chandler, D. G.

    2014-12-01

    Accurate measurement of microtopography plays an important role in fluvial geomorphology. Whereof the surface is obscured by vegetation or landform, airborne remote sensing can be impractical and ground-based surveys using terrestrial laser scanning (TLS) show promise. TLS provides high resolution observations of the land surface for relatively low cost and with simple setup. However, the scanning range is effectively limited to less than 100 m, requiring individual scenes to be merged in software to represent larger landforms. For studies requiring several scenes, an efficient scanning strategy should be established in advance to optimize for time, resolution and spatial coverage. This requires careful consideration of scanner placement to merge scenes. We address problems encountered with blind spots. TLS is generally conducted on a 2-m (or shorter) tripod and the low scanning angle to the land surface at long distance inevitably causes blind spots in rugose or complex terrain. Similarly, the distance between TLS placement points is limited by the ability to resolve matching targets from sequential surveys. Here we present a simple geometry-based scanning plan regardless of the type and range of the instrument, with modification of the survey instrument platform. The half of a minimum range is used to make at least 18% of a superposed area with the next scan. Since scanning height barely affects the scanning range, the tripod was substituted to a 3-m stepladder and the platform of the scanner was modified to level and adjust the device easily with one hand. The results show that the new scanning plan performs well regardless of the topography and figure of the area of interest, with sufficient superposed area for combination with other adjacent scans. The modification of the platform also turned out to be more efficient to secure the observing angle and improve usability. The physical enhancement for TLS will provide valuable opportunity to conduct a standardized and field-oriented work in a practical manner.

  11. Aeolian and fluvial processes in dryland regions: the need for integrated studies

    USGS Publications Warehouse

    Belnap, Jayne; Munson, Seth M.; Field, Jason P.

    2011-01-01

    Aeolian and fluvial processes play a fundamental role in dryland regions of the world and have important environmental and ecological consequences from local to global scales. Although both processes operate over similar spatial and temporal scales and are likely strongly coupled in many dryland systems, aeolian and fluvial processes have traditionally been studied separately, making it difficult to assess their relative importance in drylands, as well as their potential for synergistic interaction. Land degradation by accelerated wind and water erosion is a major problem throughout the world's drylands, and although recent studies suggest that these processes likely interact across broad spatial and temporal scales to amplify the transport of soil resources from and within drylands, many researchers and land managers continue to view them as separate and unrelated processes. Here, we illustrate how aeolian and fluvial sediment transport is coupled at multiple spatial and temporal scales and highlight the need for these interrelated processes to be studied from a more integrated perspective that crosses traditional disciplinary boundaries. Special attention is given to how the growing threat of climate change and land-use disturbance will influence linkages between aeolian and fluvial processes in the future. We also present emerging directions for interdisciplinary needs within the aeolian and fluvial research communities that call for better integration across a broad range of traditional disciplines such as ecology, biogeochemistry, agronomy, and soil conservation.

  12. Neotectonics and fluvial geomorphology of the Northern Sinai Peninsula

    NASA Astrophysics Data System (ADS)

    Kusky, T.; El-Baz, F.

    2000-08-01

    Large anticlinal ridges of Jurassic-Tertiary limestone in the northern Sinai Peninsula are part of the Syrian Arc Fold Belt, parts of which have been active intermittently from Late Cretaceous through the present. Recent uplift of the Syrian Arc Fold Belt is supported by quantitative indices of active tectonics including low values of mountain front sinuosity and, by recent seismicity, extending southwest past Cairo into the Fayoum Depression. The northern Sinai Desert has a climate similar to that of the adjacent part of the eastern Sahara. Sand sheets and dune fields cover its northwestern part, which is a depression extending from the Suez Canal to Wadi El-Arish. Numerous dry channels of palaeorivers and streams lead into this depression, where several temporary palaeolakes and flood overbank deposits have been identified. Some of the temporary pluvial palaeolakes developed behind natural dams formed by folds of the Syrian Arc, whereas others filled deeply-eroded fault traces. Migration of sand dunes may have blocked some channels, but the location of the dunes seems to be controlled by Recent uplift of parts of the fold belt, with the dunes residing in synclinal depressions and adjacent to fault scarps. The palaeolakes are correlated more with structures than with active dune fields. Wadi El-Arish abandoned a channel west of its present-day course, perhaps because of recent growth and uplift of the Gebel Halal Fold. This abandonment was synchronous with down-cutting of a gorge through Gebel Halal, which follows conjugate faults formed during uplift of an anticline. The presence of standing water during wetter climates in the past is supported by silt deposits and archaeological evidence of previous human habitation. The newly identified lake margin and fluvial sediments could be important targets for studying early-modern human and Neanderthal activities. In the eastern Sahara, cycles of pluvial periods that date back 320,000 years appear to correspond to interglacial stages. These indicate major global climate changes resulting in alternation of wet and dry climate episodes, which interplayed with local tectonic uplift to dramatically change the physiography of the northern Sinai.

  13. Quantification of fluvial bedload transport in glacier-connected steep mountain catchments in western Norway

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.; Laute, Katja

    2015-04-01

    Contemporary fluvial bedload transport rates are still very difficult to measure and, as a result of this, in many sites only quantitative data on fluvial suspended and solute transport are included in sediment budget studies carried out for defined drainage basin systems. During the years 2010-2013 detailed field measurements with portable impact sensors as a non-invasive technique for indirectly determining fluvial bedload transport intensity were conducted in two instrumented drainage basin systems (Erdalen and Bødalen) in the fjord landscape in western Norway. The collected impact sensor field data were calibrated with laboratory flume experiments, and the data from the impact sensor field measurements and the flume experiments were combined with field data from continuous discharge monitoring, repeated surveys of channel morphometry and sediment texture, particle tracer measurements, Helley-Smith samplings, underwater video filming and biofilm analyses. The combination of methods and techniques applied provides insights into the temporal variability and intensity of fluvial bedload transport in the selected mountain streams of both drainage basin systems. The conducted analysis of fluvial bedload dynamics in different defined subsystems of Erdalen (79.5 km2) and Bødalen (60.1 km2) provides information on (i) detectable relevant sediment sources, (ii) instream channel storage of bedload material, (iii) spatiotemporal variability and controls of bedload transport rates and bedload yields, and (iv) the absolute and relative importance of fluvial bedload transport within the sedimentary budgets of these steep cold climate mountain catchments. Rockfalls, snow avalanches, stream channel bank erosion, and fluvial transfers through small tributaries draining slope systems are relevant sediment sources for fluvial bedload transport in the main stream channels, whereas the main outlet glaciers in both catchment systems are not of importance as all bedload material delivered directly from these outlet glaciers is trapped within proglacial lakes. Snow avalanches are the most important sediment source in Erdalen, whereas fluvial transfers through small tributaries followed by snow avalanches are most important in Bødalen. Narrow valleys within both drainage basin systems are characterized by a higher intensity of slope-channel coupling and display higher rates of sediment supply from slopes into main stream channels than wider valleys. Longer-term, instream channel storage is not of great importance in the steep Bødalen catchment but currently plays an important role within the Erdalen drainage basin, which is characterized by a stepped longitudinal main valley bottom profile favoring deposition of bedload material within the less steep main channel reaches. The computed mean annual bedload yields (2010-2013) are 2.4 t km-2y-1 for the entire Erdalen and 13.3 t km-2y-1 for the entire Bødalen, which are comparably low values for steep and partly glacierized catchment systems. Because of supply-limited conditions, the intensity of fluvial bedload transport is generally more related to the availability of sediments than to channel discharge. Fluvial bedload transport accounts for about one-third of the total fluvial transport in both drainage basin systems.

  14. Pollutant fates in fluvial systems: on need of individual approach to each case study

    NASA Astrophysics Data System (ADS)

    Matys Grygar, Tomas; Elznicova, Jitka; Novakova, Tereza

    2015-04-01

    To outline the pollutant fates in fluvial systems it is necessary to combine two main kinds of knowledge: sedimentation and erosion patterns of each individual river with spatio-temporal resolution higher than in most fluvial geomorphology/sedimentology studies and timing and way how the pollutants have entered the fluvial system. Most of these aspects are commonly neglected in environmental geochemistry, a domain to which pollution studies apparently belong. In fact, only when these two main components are established (at least in a qualitative manner), we can start reading (interpretation) of the fluvial sedimentary archives, e.g., decipher the way how the primary pollution signal has been distorted during passing through the fluvial system. We conducted empirical studies on Czech rivers impacted by pollution (by risk elements). We learnt how individual (site-specific) are the main processes responsible for the primary pollution input, spread through each fluvial system and inevitable secondary pollution ("lagged pollution improvement signal"). We will discuss main features of the story on pollutant fates in three different fluvial systems, which have not been impacted by "hard" river engineering and still undergo natural fluvial processes: 1. the Ohre (the Eger) impacted by production of Hg and its compounds, historical mining of Pb and more recent U ore processing, 2. the Ploucnice impacted by U mining, and 3. the Litavka, impacted by Pb-Zn(-Sb) mining and smelting. The Ohre is specific by most pollution having been temporarily deposited in an active channel, only minor reworking of older fluvial deposits diluting pollution during downstream transport, and pollution archives existing practically only in the form of lateral accretion deposits. The deposits of archive value are rare and can be revealed by detailed study of historical maps and well-planned field analysis, best using portable analytical instruments (XRF). The Ploucnice is specific by only transient deposition in a channel belt and subsequent secondary pollution via physical mobilisation, most pollution storing in the floodplain in a surprisingly heterogeneous manner - in hotspots with a size comparable to fragments of abandoned channels (from a few to few tens of metres). The hotspots are hence best revealed by well-designed field analysis using portable instruments (gamma spectrometry or XRF). The Litavka is specific because most pollution is in its floodplain in the form of anthropogenic alluvium, a very thick vertical accretion body of "artificial" material added to the river system in the amount exceeding its normal transport capacity. That situation favours secondary pollution by chemical mobilisation of pollutants under low river discharges revealed by geochemical analysis. Our case studies show that simple "rules" such as continuous decay of pollutant concentrations downstream from the pollution source, existence of a continuous blanket of polluted overbank fines in floodplain, simple change of the pollution extent with growing distance from the river channel and as a consequence of extreme floods, or simple recipes such as low-density sampling to trace point pollution sources are too simplistic to be applicable in real polluted fluvial systems. Each river system represents a nearly unique combination of individual geomorphic processes, and each pollution has been specific by the mode how it entered the fluvial system. We will not offer "magic tools" in our contribution. In literature we can find all pieces we need for the jigsaw puzzle - pollutants fates in fluvial systems. The question is why so rarely researchers put them together. We would like to encourage them to do so.

  15. Contrasting fluvial styles of the Paraguay River in the northwestern border of the Pantanal wetland, Brazil

    NASA Astrophysics Data System (ADS)

    Assine, Mario Luis; Silva, Aguinaldo

    2009-12-01

    The Upper Paraguay drainage basin is situated mainly in west-central Brazil, near the Bolivian border. Flowing from north to south, the Paraguay is the trunk river of an alluvial depositional tract characterized by complex geomorphologic zonation that resulted from an intricate geologic evolution since the Late Pleistocene. This paper focuses on the geomorphology of the Paraguay River at the northwestern border of the Pantanal wetland, where two broad geomorphologic zones were distinguished. North from the Pantanal wetland, the Paraguay River flows in an aggradational fluvial plain, 5 km wide and incised into older alluvial deposits. The river exhibits a meandering style over most of its course, but sinuosity drops from 2.2 to 1.1 near the northwest border of the Pantanal wetland where the river has been forming the Paraguay fluvial megafan since the Late Pleistocene. The river deflects 90° eastward at the entrance into the Pantanal, changing its fluvial style because of a progressive loss of confinement downstream of the point where the river reaches lowland plains. The river becomes more sinuous, adopts a distributary pattern within the wetland and brings about the creation of the modern depositional lobe characterized by higher topographic gradient and active sedimentation likely linked to increased accommodation space allowing progradation. Fluvial discharge diminishes in the Pantanal wetland because of channel overbank flow during the rainy season and frequent levee crevassing. Avulsion belts and channel-levee complex are preserved on the floodplain as relict forms. South of the convergence of the two main channels that define the Taiamã Island, a loss of gradient marks the base of the depositional lobe. Further downstream, the Paraguay River returns to a meandering fluvial style, but crossing a large fluvial plain populated by hundreds of small lakes and seasonally flooded that characterizes the Pantanal wetland.

  16. Integrated assessment of fluvial and pluvial flood hazards in the city of Salzburg, Austria

    NASA Astrophysics Data System (ADS)

    Breinl, Korbinian

    2014-05-01

    Urban flooding can have various sources including floods from a river ('fluvial flooding'), from heavy rainfall usually from convective storms ('pluvial flooding') or from high tides ('storm surge'). Although awareness of pluvial flooding in the scientific community and among policymakers has been increasing, the term 'flooding' is still often seen as a phenomenon explicitly related to a river. Previous research primarily focused on fluvial flooding, with only very recent literature dealing with pluvial flooding. As a result, there are established methods to assess the hazards from fluvial floods, and a smaller number focusing on pluvial floods. Much less work has been conducted on integrated flood hazard assessment taking into account various types of flood hazards. In this work, an integrative, probabilistic modelling framework was developed to assess the urban flood hazard from fluvial and pluvial flooding in the city of Salzburg (Austria). The framework consists of a stochastic multi-site weather generator, which provides input for the hydrological model HBV. In the city of Salzburg, a kNN algorithm converts the simulated mean discharge into peak discharge as well as daily into sub-daily precipitation. The time series generated in this way make the identification of fluvial events (peak discharge) and pluvial events (sub-daily precipitation) possible. The kNN algorithm inherently considers weather situations to ensure a reasonable disaggregation of daily precipitation. Critical thresholds of pluvial flood events are empirically derived from damage data provided by a local insurer as well as action plans from the local fire service. The modelling framework is then applied to examine the probability of the two single flood hazards, as well as the probability of simultaneous pluvial-fluvial flood events.

  17. Integrated stratigraphy of Paleocene lignite seams of the fluvial Tullock Formation, Montana (USA).

    NASA Astrophysics Data System (ADS)

    Noorbergen, Lars J.; Kuiper, Klaudia F.; Hilgen, Frederik J.; Krijgsman, Wout; Dekkers, Mark J.; Smit, Jan; Abels, Hemmo A.

    2015-04-01

    Coal-bearing fluvial sedimentation is generally thought to be dominated by autogenic processes that are processes intrinsic to the sedimentary system. Ongoing research however suggests that several fluvial processes such as floodplain inundation and avulsion, can also be controlled by external forcing such as orbital climate change. Still, the exact role of orbital climate forcing in fluvial sediments is difficult to decipher since riverine deposits are complicated by variable sedimentation rates including erosion of previously deposited material, by lateral heterogeneity of sedimentation, and by scarcity of independent dating methods. The early Paleocene lignite-bearing Tullock Formation of the Williston Basin in eastern Montana represents a record of fluvial sedimentation that is perfectly exposed and, displays a seemingly regular alternation of sandstones and lignite seams. These coal beds contain multiple volcanic ash layers. Here, we use an integrated stratigraphic approach (litho- and magnetostratigraphy, geochemical fingerprinting and radio-isotope dating of volcanic ash layers) to establish a high-resolution time frame for the early Paleocene fluvial sediments. First age estimations indicate that the Tullock Formation in Eastern Montana was deposited over a time span of ~ 1000 kyr subsequent to the Cretaceous - Paleogene boundary, dated at ~ 65.95 Ma [1]. Initial high-resolution magnetostratigraphy revealed the occurrence of the C29r/C29n polarity reversal which was stratigraphic consistent at different field locations. We investigate the regional significance of sedimentary change at multiple sites of the same age in order to provide improved insight on the role of orbital forcing in fluvial coal formation. References: [1] Kuiper, K.F., Deino, A., Hilgen, F.J., Krijgsman, W., Renne, P.R., Wijbrans, J.R. (2008). Synchronizing Rock Clocks of Earth History. Science 320, 500-504.

  18. Debris Flow Control on Fluvial Hanging Valley Formation in the South Fork Eel River, CA

    NASA Astrophysics Data System (ADS)

    Deshpande, N.; Perkins, J.; Finnegan, N. J.

    2012-12-01

    An understanding of how base level signals are transmitted into landscapes is fundamental to interpreting river long profiles in tectonically active settings. Fluvial hanging valleys, locations where waves of incision have apparently arrested at tributary junctions, suggest that base level propagation is an unsteady process in many settings. A recent hypothesis (Wobus et al., 2006) explains the formation of fluvial hanging valleys via an instability in the saltation abrasion model of Sklar and Dietrich (2004). At locations where small steep tributaries join trunk streams, tributary incision rates can actually decrease with increasing channel slope when subjected to downstream base-level fall. However, we note that in mountainous river networks steep tributaries also commonly convey debris flows into trunk channels. Since these tributary junctions mark the upstream limit of channels whose beds are mobilized on a regular basis during flood events, here we hypothesize that transitions from fluvial to debris flow channels control the location of fluvial hanging valleys. To test our hypothesis, we exploit a natural experiment in base level fall and landscape evolution along the South Fork Eel River, which is argued to be responding to an increase in rock uplift rate associated with the passage of the Mendocino Triple Junction. In order to separate debris flow channels from fluvial channels, we use airborne laser swath mapping (ALSM) to quantify channel slopes and concavities. In our analysis, concavity data are noisy and represent a poor metric for determination of debris flow channels. In lieu of this, we choose a more straightforward metric of channel slope to discriminate where debris flows occur on the landscape. We find that, on average, fluvial hanging valleys are only present in tributaries with average gradients above 0.10, consistent with empirical determinations of the gradient at which debris flow channels transition to fluvial channels (0.03-0.10). Field observations in selected tributaries confirm our interpretation of the topographic analysis and thereby lend support to our hypothesis. Our results contradict Wobus et al. (2006) who find through a topographic analysis of tributaries in the eastern Central Range of Taiwan that channels exhibiting a signature of debris flows in slope-area space do not form hanging valleys or display evidence of a transient response. Possible explanations for this discrepancy lie in the scale of topographic data used in the respective analyses, as well as the spatial scale of the study areas themselves. Regardless, our observations of systematically steeper slopes (above the debris flow threshold) upstream of fluvial hanging valleys along the South Fork Eel River, CA suggest a process transition may be responsible for the morphologic changes observed here.

  19. Three-dimensional geometry of fluvial reservoir sands: steam-drive case study

    SciTech Connect

    McPherson, J.G.; Miller, D.D.

    1989-03-01

    The three-dimensional geometry of fluvial sands in South Belridge heavy oil field was investigated as part of an Enhanced Oil Recovery study. It was shown that only close-spaced well data are sufficient to define the sand-body geometries and heterogeneities of multichannelled fluvial systems. Reservoir flow-unit patterns cannot necessarily be correctly delineated by isolated vertical sequence analysis. Wireline logs from 19 wells and conventional cores from seven wells in a 10-ac (660 ft x 660 ft) pattern were correlated in detail, using additional input from sedimentology, steam-flow patterns, and reservoir flow-unit continuity.

  20. Fluvial network analysis on Titan: Evidence for subsurface structures and west-to-east wind flow, southwestern Xanadu

    E-print Network

    Perfect, Ed

    Fluvial network analysis on Titan: Evidence for subsurface structures and west-to-east wind flow; published 25 November 2009. [1] Data of Titan's surface from the Cassini-Huygens mission show inferred, indicating that a variety of factors control fluvial drainage on Titan. Drainage network patterns

  1. Toward a more holistic perspective of soil erosion: Why aeolian research needs to explicitly consider fluvial processes and interactions

    NASA Astrophysics Data System (ADS)

    Field, Jason P.; Breshears, David D.; Whicker, Jeffrey J.

    Soil erosion is driven by not only aeolian but also fluvial transport processes, yet these two types of processes are usually studied independently, thereby precluding effective assessment of overall erosion, potential interactions between the two drivers, and their relative sensitivities to projected changes in climate and land use. Here we provide a perspective that aeolian and fluvial transport processes need to be considered in concert relative to total erosion and to potential interactions, that relative dominance and sensitivity to disturbance vary with mean annual precipitation, and that there are important scale-dependencies associated with aeolian-fluvial interactions. We build on previous literature to present relevant conceptual syntheses highlighting these issues. We then highlight relative investments that have been made in soil erosion and sediment control by comparing the amount of resources allocated to aeolian and fluvial research using readily available metrics. Literature searches suggest that aeolian transport may be somewhat understudied relative to fluvial transport and, most importantly, that only a relatively small number of studies explicitly consider both aeolian and fluvial transport processes. Numerous environmental issues associated with intensification of land use and climate change impacts depend on not only overall erosion rates but also on differences and interactions between aeolian and fluvial processes. Therefore, a more holistic viewpoint of erosional processes that explicitly considers both aeolian and fluvial processes and their interactions is needed to optimize management and deployment of resources to address imminent changes in land use and climate.

  2. Testing fluvial erosion models using the transient response of bedrock rivers to tectonic forcing in the Apennines, Italy

    E-print Network

    Cowie, Patience

    Testing fluvial erosion models using the transient response of bedrock rivers to tectonic forcing fluvial erosion models. However, some recent studies of bedrock erosion conclude that transient river long profiles can be approximately characterized by a transportlimited erosion model, while other authors

  3. Aves acuáticas de la Laguna de Agua Dulce y el Estero El Ermitaño, Jalisco, México

    Microsoft Academic Search

    Salvador Hernández Vázquez

    2005-01-01

    Water birds from Agua Dulce lake and El Ermitaño estuary, Jalisco, Mexico. Waterbird abundance, and seasonal and spatial distribution, were studied in two natural water pools at Jalisco, México, from December 1997 through November 1998. Maximum monthly abundance in Agua Dulce lake and El Ermitaño estuary was 86 471 birds (29 686 in Agua Dulce and 56 785 in Ermitaño),

  4. Late Cenozoic fluvial development within the Sea of Azov and Black Sea coastal plains

    Microsoft Academic Search

    A. Matoshko; P. Gozhik; V. Semenenko

    2009-01-01

    Late Cenozoic terrestrial deposits are widespread across the northern coastal regions of the Black Sea and the Sea of Azov and represent diverse fluvial, estuarine and deltaic environments. The dating and correlation of these deposits rely on stratigraphically-associated marine index beds, mammalian and molluscan faunas and magnetostratigraphy. In detail the geometries of these sediment bodies are extremely complex, typically varying

  5. A mechanistic detachment rate model to predict soil erodibility due to fluvial and seepage forces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The erosion rate of cohesive soils is typically computed using an excess shear stress model based on the applied fluvial shear stress. However, no mechanistic approaches are available for incorporating additional forces such as localized groundwater seepage forces into the excess shear stress model...

  6. Variables and potential models for the bleaching of luminescence signals in fluvial environments

    USGS Publications Warehouse

    Gray, Harrison J.; Mahan, Shannon A.

    2015-01-01

    Luminescence dating of fluvial sediments rests on the assumption that sufficient sunlight is available to remove a previously obtained signal in a process deemed bleaching. However, luminescence signals obtained from sediment in the active channels of rivers often contain residual signals. This paper explores and attempts to build theoretical models for the bleaching of luminescence signals in fluvial settings. We present two models, one for sediment transported in an episodic manner, such as flood-driven washes in arid environments, and one for sediment transported in a continuous manner, such as in large continental scale rivers. The episodic flow model assumes that the majority of sediment is bleached while exposed to sunlight at the near surface between flood events and predicts a power-law decay in luminescence signal with downstream transport distance. The continuous flow model is developed by combining the Beer–Lambert law for the attenuation of light through a water column with a general-order kinetics equation to produce an equation with the form of a double negative exponential. The inflection point of this equation is compared with the sediment concentration from a Rouse profile to derive a non-dimensional number capable of assessing the likely extent of bleaching for a given set of luminescence and fluvial parameters. Although these models are theoretically based and not yet necessarily applicable to real-world fluvial systems, we introduce these ideas to stimulate discussion and encourage the development of comprehensive bleaching models with predictive power.

  7. Fluvial sediment transport and deposition following the 1991 eruption of Mount Pinatubo

    E-print Network

    Montgomery, David R.

    ), detailed work follow- ing the 1980 eruption of Mount St. Helens increased recognition of the potentialFluvial sediment transport and deposition following the 1991 eruption of Mount Pinatubo Shannon K 2001 Abstract The 1991 eruption of Mount Pinatubo generated extreme sediment yields from watersheds

  8. Characterizing physical habitats in rivers using map-derived drivers of fluvial geomorphic processes

    NASA Astrophysics Data System (ADS)

    Bizzi, Simone; Lerner, David N.

    2012-10-01

    New understanding of fluvial geomorphological processes has successfully informed flood mitigation strategies and rehabilitation schemes in recent years. However well established geomorphological assessments are location-specific and demanding in terms of resource and expertise required, and their routine application for regional or national river characterization, although desirable, is unlikely at present. This paper proposes a framework based on GIS procedures, empirical relationships and the self organized map for the analysis and classification of map-derived drivers of fluvial morphological processes. The geomorphic controls analysed are: channel gradient and hydrology, specific stream power, river order and floodplain extent. The case study is a gravel bed river in England. Using the self organized map, we analyse patterns of these controls along the river longitudinal profile and identify clusters of similar configuration. The reciprocal relationships that emerge amongst the geomorphic controls reflect the hierarchical nature of fluvial systems and are consistent with the current theoretical understanding of fluvial processes. Field observations from the River Habitat Survey are used to prove the influence of geomorphic drivers on reach-scale morphological forms. Six clusters are identified which describe six distinctive channel types. These proved to be characterized by distinctive configurations of geomorphic drivers and specific sets of physical habitat features. The method successfully characterizes the notable transitions in channel character along the river course. The framework is suitable for regional or national scale assessments through automatic GIS and statistical procedures with moderate effort.

  9. Ecosystem matters: Fish consumption, mercury intake and exposure among fluvial lake fish-eaters

    E-print Network

    Long, Bernard

    Ecosystem matters: Fish consumption, mercury intake and exposure among fluvial lake fish communities from 2 ecosystems in Quebec, Canada, sought to (i) estimate Hg intake from local freshwater. Furthermore, most freshwater advisories only refer to local catch, while market fish advisories only focus

  10. A model for fluvial bedrock incision by impacting suspended and bed load sediment

    E-print Network

    A model for fluvial bedrock incision by impacting suspended and bed load sediment Michael P. Lamb,1 bed and suspended load. The erosion rate is equated to the product of the impact rate, the mass loss per particle impact, and a bed coverage term. Unlike previous models that consider only bed load

  11. Fluvial response to rapid episodic erosion by earthquake and typhoons, Tachia River, central Taiwan

    E-print Network

    Montgomery, David R.

    Fluvial response to rapid episodic erosion by earthquake and typhoons, Tachia River, central Taiwan Earthquake Typhoon Erosion Channel response Analysis of typhoon- and earthquake-triggered landsliding decade to century timescales. Landslide data from the Chi-Chi earthquake (1999) and subsequent typhoons

  12. Fluvial incision and tectonic uplift across the Himalayas of central Nepal

    Microsoft Academic Search

    J. Lavband; J. P. Avouac

    2001-01-01

    The pattern of fluvial incision across the Himalayas of central Nepal is estimated from the distribution of Holocene and Pleistocene terraces and from the geometry of modern channels along major rivers draining across the range. The terraces provide good constraints on incision rates across the Himalayan frontal folds (Sub-Himalaya or Siwaliks Hills) where rivers are forced to cut down into

  13. MODIFICATION OF PHOSPHORUS EXPORT FROM A CATCHMENT BY FLUVIAL SEDIMENT PHOSPHORUS INPUTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphorus (P) export from agricultural watersheds can accelerate freshwater eutrophication. Landscape-based remedial measures can reduce edge-of-field P losses. However stream channel hydraulics and fluvial sediment properties can modify the forms and amounts of P exported by the time it reaches th...

  14. Mixed fluvial systems of Messak Sandstone, a deposit of Nubian lithofacies, southwestern Libya

    SciTech Connect

    Lorenz, J.C.

    1987-05-01

    The Messak Sandstone is a coarse to pebbly, tabular cross-bedded, Lower Cretaceous deposit of the widespread Nubian lithofacies. It was deposited at the northern edge of the Murzuq basin in southwestern Libya. Although the sedimentary record is predominantly one of braided fluvial systems, a common subfacies within the formation is interpreted to record the passage of straight-crested sand waves across laterally migrating point bars in sinuous rivers, similar to the pattern documented by Singh and Kumar on the modern Ganga and Yamuna Rivers. Because the sand waves were larger on the lower parts of the point bars, lateral migration created diagnostic thinning-upward, unidirectional cosets of tabular cross-beds as well as fining-upward, grain-size trends. Common, thick, interbedded claystones, deposited in associated paludal and lacustrine environments, and high variance in cross-bed dispersion patterns also suggest the local presence of sinuous fluvial systems within the overall braided regime. The Messak Sandstone contains some of the features that led Harms et al to propose an unconventional low-sinuosity fluvial environment for the Nubian lithofacies in Egypt, and the continuously high water levels of this model may explain channel-scale clay drapes and overturned cross-beds in the Messak. However, most of the Messak characteristics are incompatible with the low-sinuosity model, suggesting instead that the fluvial channels in the Murzuq basin alternated between braided and high-sinuosity patterns.

  15. Generalized hydraulic geometry: Insights based on fluvial instability analysis and a physical model

    E-print Network

    Foufoula-Georgiou, Efi

    asymmetry over reaches of increasing scale. To test this hypothesis, we employ both a direct analysis; 1821 Hydrology: Floods; KEYWORDS: channel asymmetry, floods, fluvial instability, hydraulic geometry through some char- acteristic discharge, e.g., mean annual discharge (referred to as downstream HG

  16. Fluvial bedrock incision in the active mountain belt of Taiwan fromin situ-produced cosmogenic nuclides

    Microsoft Academic Search

    M. Schaller; N. Hovius; S. D. Willett; S. Ivy-Ochs; H.-A. Synal; M.-C. Chen

    2005-01-01

    The concentration of cosmogenic nuclides in rocks exposed at the Earth's surface is propor- tional to the total duration of their exposure. This is the basis for bedrock surface exposure dating and has been used to constrain valley lowering rates in the Taroko gorge, eastern Central Range, Taiwan. Taroko gorge contains a uniquely complete geomorphic record of fluvial valley lowering:

  17. Volcanogenic Fluvial-Lacustrine Environments in Iceland and Their Utility for Identifying Past Habitability on Mars

    PubMed Central

    Cousins, Claire

    2015-01-01

    The search for once-habitable locations on Mars is increasingly focused on environments dominated by fluvial and lacustrine processes, such as those investigated by the Mars Science Laboratory Curiosity rover. The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures. Fluvial-lacustrine environments associated with basaltic volcanism are highly relevant to Mars, but their terrestrial counterparts have been largely overlooked as a field analogue. Such environments are common in Iceland, where basaltic volcanism interacts with glacial ice and surface snow to produce large volumes of meltwater within an otherwise cold and dry environment. This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems. Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite), and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides). This paper reviews examples of these environments, including their sedimentary deposits and microbiology, within the context of utilising these localities for future Mars analogue studies and instrument testing. PMID:25692905

  18. Salida de operadores privados internacionales de agua en América Latina

    Microsoft Academic Search

    Jorge Ducci

    2007-01-01

    Hacia fines de los años noventa un número significativo de países de América Latina contaba con la presencia de importantes operadores internacionales en el sector de servicios de agua potable y alcantarillado. Se esperaba que este proceso se siguiera expandiendo y profundizando. Sin embargo, a mediados de la primera década del nuevo siglo se observa que la mayoría de los

  19. Climate-sensitive feedbacks between hillslope processes and fluvial erosion in sediment-driven incision models

    NASA Astrophysics Data System (ADS)

    Skov, Daniel; Egholm, David

    2015-04-01

    Surface erosion and sediment production accelerated dramatically in most parts of the world as the climate cooled in the Late Cenozoic, (e.g. Molnar, Annu. Rev. Earth Planet. Sci. 32, 2004). In many high mountain ranges, glaciers emerged for the first time during the Quaternary, and they represent a likely explanation for the accelerated erosion in such places. Still, observations and measurements point to increases in erosion rate also in landscapes where erosion is driven mainly by fluvial processes (e.g. Lease and Ehlers, Science 341, 2013). Why fluvial incision responds to climate change remains enigmatic, in particular because the obvious links to variations in precipitation, and hence water flux, are not generally supported by erosion rate measures (Stock et al., GSA Bulletin 117, 2005). This study explores potential links between accelerating rates of river incision and sediment production on hillslopes that surround the channel network. Hillslope soil production and soil transport are processes that are likely to respond to decreasing temperatures, because the density of vegetation and for example the occurrence of frost influence rates of weathering and sediment flow. We perform computational landscape evolution experiments where a sediment-flux-dependent model for fluvial incision (e.g. Sklar and Dietrich, Geology 29, 2001) is coupled to models for sediment production and transport on hillslopes. The resulting coupled landscape dynamics is of a highly nonlinear nature, where even small changes in hillslope sediment production far up in a drainage network propagate all the way through the downstream fluvial system. Dependent on the total sediment load, the fluvial system may respond with increased incision that steepens the hillslopes and starts a positive feedback loop that accelerates overall erosion.

  20. Application of Uav Photogrammetry for Assessment of Fluvial Dynamics of a Montane Stream. Case Study - Roklanský Creek, Šumava Mts., Europe.

    NASA Astrophysics Data System (ADS)

    Langhammer, J.; Mi?ijovský, J.; Hartvich, F.; Kaiglová, J.

    2014-12-01

    Current progress in hydrology and fluvial geomorphology is largely driven by the newly emerging survey and detection techniques, employing advanced technologies for remote sensing and monitoring of the runoff processes and fluvial dynamics. The contribution demonstrates the potential of the fusion of experimental survey methods for analysis of fluvial dynamics of a montane stream. The UAV photogrammetry, optical granulometry, ground LiDAR scanning and sensor network monitoring were applied as a base for building hydrodynamic model for simulation of fluvial dynamics. The UAV photogrammetry is employed to acquire high precision DTM and especially for quantitative analysis of volumetric changes related to initial flood events. The hexacopter platform has been used to acquire the data for photogrammetric analysis of complex stretch of stream with historically elevated fluvial dynamics. The SfM algorithm was used to extract accurate DTM of the channel and to consequently analyze the volumetric changes after a flood event. The sensor network with automated high frequency water level monitoring was used to derive information on hydrological properties of initial flood event. The digital granulometry enabled to analyze the structure of sedimentary material in floodplain. The terrestrial LiDAR scanning allows construction of very detailed 3D models of selected fluvial forms, enabling deeper insight into the effects of fluvial dynamics and to verify the spatial information acquired using UAS photogrammetry. The results of above mentioned techniques are applied to build hydrodynamic model explaining threshold conditions for initiation of changes in fluvial morphology of the riverbed in relation to known and theoretical flood magnitude. The results achieved in the study enabled us to discuss the synergic potential of coupling the UAV photogrammetry, sensor networks and other high precision survey techniques to enhance significantly our knowledge on the dynamics of fluvial systems.

  1. The potential of hydrodynamic analysis for the interpretation of Martian fluvial activities

    NASA Astrophysics Data System (ADS)

    Kim, Jungrack; Schumann, Guy; Neal, Jeffrey; Lin, Shih-Yuan

    2014-05-01

    After liquid water was identified as the agent of ancient Martian fluvial activities, the valley and channels on the Martian surface were investigated by a number of remote sensing and in-situ measurements. In particular, the stereo DTMs and ortho images from various successful orbital sensors are being effectively used to trace the origin and consequences of Martian hydrological channels. For instance, to analyze the Martian fluvial activities more quantitatively using the topographic products, Burr et al. (2003) employed 1D hydrodynamic models such as HEC-RAS together with the topography by MOLA to derive water flow estimates for the Athabasca Valles area on Mars [1]. Where extensive floodplain flows or detailed 2D bathymetry for the river channel exist, it may be more accurate to simulate flows in two dimensions, especially if the direction of flow is unclear a priori. Thus in this study we demonstrated a quantitative modeling method utilizing multi-resolution Martian DTMs, constructed in line with Kim and Muller's (2009) [2] approach, and an advanced hydraulics model LISFLOOD-FP (Bates et al., 2010) [3], which simulates in-channel dynamic wave behavior by solving for 2D shallow water equations without advection. Martian gravitation and manning constants were adjusted in the hydraulic model and the inflow values were iteratively refined from the outputs of the coarser to the finer model. Then we chose the target areas among Martian fluvial geomorphologies and tested the effectiveness of high resolution hydraulic modeling to retrieve the characteristics of fluvial systems. Test sites were established in the Athabasca Valles, Bahram Vallis, and Naktong Vallis respectively. Since those sites are proposed to be originated by different fluvial mechanisms, it is expected that the outputs from hydraulics modeling will provide important clues about the evolution of each fluvial system. Hydraulics modeling in the test areas with terrestrial simulation parameters was also conducted to explore the different characteristics of two planets' fluvial activities. Ultimately, this study proved the effectiveness of multi-resolution modeling using 150-1.2m DTMs and 2D hydraulics to study the Martian fluvial system. In future study, we will elaborate the hydrodynamic model to investigate the sediment transformation mechanism in Martian fluvial activities using hydrodynamic properties such as flow speed. References: [1] Burr, D.M. (2003).Hydraulic modelling of Athabasca Vallis, Mars. Hydrological Sciences Journal, 48(4), 655-664. [2] Kim, J.R. & Muller, J-P.,(2009).Multi resolution topographic data extraction from Martian stereo imagery.Planetary and Space Science. 57, 2095-2112. [3] Bates, P.D., Horritt, M.S., & Fewtrell, T.J. (2010). A simple inertial formulation of the shallow water equations for efficient two-dimensional flood inundation modelling. Journal of Hydrology, 387(1), 33-45.

  2. Using portable impact sensors for analyzing fluvial bedload transport in steep mountain streams

    NASA Astrophysics Data System (ADS)

    Beylich, A.; Laute, K.

    2013-12-01

    The timing and rate of fluvial bedload transport are of central importance in quantitative studies on fluvial transport, within sediment budget studies, and in many applications in river science and engineering. Bedload transport rates are still comparably difficult to measure and, in many sites, only suspended load and solute load data are actually included in fluvial sediment budget studies. Detailed field measurements with portable impact sensors as a comparably new and non-invasive technique for indirectly determining fluvial bedload transport intensity have been conducted since 2010 in two instrumented and supply-limited mountainous drainage basin systems (Erdalen and Bødalen) in western Norway. Additional field measurements with portable impact sensors were carried out in three selected transport-limited fluvial systems in the Coast Mountains of western Canada. The collected impact sensor field data were calibrated with laboratory impact sensor flume experiments. In the transport-limited systems (in western Canada) with generally high bedload transport rates during high discharge and with bedload moving in clusters over the impact sensor plates, impact sensor data (based on a 1 s measuring interval) provide the opportunity to detect the start and end of bedload transport, thus to identify discharge thresholds for sediment entrainment, and to roughly estimate the intensity and relative intensity changes of bedload transport during the measuring period. In the supply-limited systems (in western Norway) with generally low bedload transport rates and bedload components moving separately (as single particles) over the impact sensor plates, impact sensor data (based on a 1 s measuring interval) allow the detection of the start and end of transport of bedload components >11.3 mm, thus the identification of discharge thresholds for possible entrainment of particles, the quantification of the number of particles >11.3 mm moving over the impact sensor plates during the measuring period, the rough estimation of grain sizes of the particles >11.3 mm moving separately over the impact sensor plates, and the calculation of the total mass of the bedload material >11.3 mm moving over the impact sensor plates during the measuring period. When combined with other bedload measuring methods and techniques (Helley-Smith sampling, particle tracer measurements, biofilm analyses, underwater video filming) which have provided information on the active bedload transport channel width, on discharge thresholds for possible entrainment of particles of different grain sizes, and on transport rates of bedload material <11.3 mm, total rates of fluvial bedload transport, covering all given grain sizes of the bedload material, can be calculated for the supply-limited mountain streams with generally low bedload transport. The higher computed mean annual bedload yield in Bødalen (13.6 t km-2yr-1) compared to Erdalen (2.6 t km-2yr-1) reflects a higher level of slope-channel coupling in the Bødalen drainage basin than in Erdalen. In both drainage basins fluvial bedload transport is smaller than fluvial suspended sediment transport. In Bødalen the annual fluvial bedload yield is two times greater than annual chemical denudation whereas in Erdalen it is less than half of the annual chemical denudation rate.

  3. Fluvial Channel Networks as Analogs for the Ridge-forming Unit, Sinus Meridiani, Mars

    NASA Astrophysics Data System (ADS)

    Wilkinson, M. J.; Dubois, J. B.

    2010-12-01

    Fluvial models have been generally discounted as analogs for the younger layered rock units of Sinus Meridiani. A fluvial model based on the large fluvial fan provides a possibly close analog for various features of the sinuous ridges of the etched, ridge-forming unit (RFU) in particular. The close spacing of the RFU ridges, their apparently chaotic orientations, and their organization in dense networks all appear unlike classical stream channel patterns. However, drainage patterns on large fluvial fans—low-angle, fluvial aggradational features, 100s of km long, documented worldwide by us—provide parallels. Some large fan characteristics resemble those of classical floodplains, but many differences have been demonstrated. One major distinction relevant to the RFU is that channel landscapes of large fans can dominate large areas (1.2 million km2 in one S. American study area). We compare channel morphologies on large fans in the southern Sahara Desert with ridge patterns in Sinus Meridiani (fig 1). Stream channels are the dominant landform on large terrestrial fans: they may equate to the ubiquitous, sinuous, elongated ridges of the RFU that cover areas region wide. Networks of convergent/divergent and crossing channels may equate to similar features in the ridge networks. Downslope divergence is absent in channels of terrestrial upland erosional landscapes (fig. 1, left), whereas it is common to both large fans (fig. 1, center) and RFU ridge patterns (fig 1, right—downslope defined as the regional NW slope of Sinus Meridiani). RFU ridge orientation, judged from those areas apparently devoid of impact crater control, is broadly parallel with the regional slope (arrow, fig. 1, right), as is mean orientation of major channels on large fans (arrow, fig. 1, center). High densities per unit area characterize fan channels and martian ridges—reaching an order of magnitude higher than those in uplands just upstream of the terrestrial study areas—fig. 1. In concert with several other regional features, these morphological similarities argue for the RFU as a possibly fluvial unit. Figure 1. Channel patterns in Saharan upland and lowland landscapes, compared to RFU ridge patterns. Left panel—southern Sudan uplands (ctr 11.1N 28.4E); center panel—part of a large fan, Muglad basin, immediately downstream of sediment-source upland shown in left panel (10.15N 28.6E); right panel—discontinuous inverted ridge patterns, Mars (ctr 2.1N 1.0W). Arrows show direction of regional stream flow (left, center panels) and regional slope in Mars study area (right panel). North to top.

  4. Three-dimensional fluvial-deltaic sequence stratigraphy Pliocene-Recent Muda Formation, Belida Field, West Natuna Basin, Indonesia 

    E-print Network

    Darmadi, Yan

    2007-04-25

    for sediment dispersal and accumulation. The Muda interval contains five third-order sequences, with depositional environments confined to the shelf and consisting mainly of fluvial elements. Sequence boundaries (SB) apparently result from major sea level falls...

  5. Stratigraphic and Sedimentological Evidence for a Large-Scale Coarse-Grained Fluvial System (Southwest Shoulder of Juventae Chasma)

    NASA Astrophysics Data System (ADS)

    Ori, G. G.; Salese, F.

    2011-03-01

    The Southwestern shoulder of the Juventae Chasma shows an extensive set of exhumed channels. The cliff bordering the Juventae Chasma cuts this fluvial system showing a conglomeratic unit interpreted as the result of braided channels deposition.

  6. Application of UAS photogrammetry for assessment of flood driven fluvial dynamics of montane stream. Case study - Roklansky creek, Sumava Mts.

    NASA Astrophysics Data System (ADS)

    Langhammer, Jakub; Mi?ijovský, Jakub; Hartvich, Filip; Kaiglová, Jana

    2014-05-01

    Current progress in hydrology and fluvial geomorphology is largely based on new field survey and analysis techniques, employing advanced technologies for monitoring the dynamics of the runoff process, field surveying and for remote monitoring of changes in riverbeds and of fluvial dynamics. Application of these techniques allows researchers to obtain information on a significantly higher qualitative level than using traditional methods of field survey and measurement, either in terms of spatial accuracy and resolution, frequency of sampling or qualitative characteristics of acquired data. The contribution demonstrates the potential of Unmanned Aerial Systems (UAS) for analysis of fluvial dynamics of montane stream, driven by flood in combination with other survey techniques, namely the ground LiDAR scanning, digital granulometry and automated water level monitoring. The UAS photogrammetry is employed in the study to acquire high precision DTMs, enabling reconstruction of riverbed and quantitative analysis of volumetric changes related to initial flood events. The hexacopter UAS platform has been used to acquire the data for photogrammetric analysis of complex stretch of stream with historically elevated fluvial dynamics. The photogrammetric reconstruction enabled to build accurate DTM of riverbed and floodplain before and after the initial event and to calculate the extent of volumetric changes. The potential of UAS photogrammetry for fluvio morphological study is in combination with other monitoring and survey techniques, enabling complex analysis of fluvial dynamics. The magnitude, duration and hydrological properties of initial flood event were derived from automated high frequency water level monitoring. The digital granulometry enabled to analyze the structure of sedimentary material in floodplain. The terrestrial LiDAR scanning allows construction of very detailed 3D models of selected fluvial forms, enabling deeper insight into the effects of fluvial dynamics and to verify the spatial information acquired using UAS photogrammetry. The results of above mentioned techniques are applied to build hydrodynamic model explaining threshold conditions for initiation of changes in fluvial morphology of the riverbed in relation to known and theoretical flood magnitude. The presented study proved the UAS photogrammetry to be unique source of spatial information, allowing analysis of dynamics of fluvial systems with unprecedented precision and flexibility. This technique has full potential to bring spatial information to a new qualitative level and in experimental areas with limited availability of spatial information. The preliminary results achieved in the study enabled us to discuss the synergic potential of coupling the UAS photogrammetry, sensor networks and other hydroinformatic techniques to enhance significantly our knowledge on the dynamics of fluvial systems. Key words: UAS photogrmmetry, DTM, fluvial processes, erosion, hydrodynamic modelling

  7. Ichnofossils and rhizoliths of the nearshore fluvial Jebel Qatrani Formation (Oligocene), Fayum Province, Egypt

    USGS Publications Warehouse

    Bown, T.M.

    1982-01-01

    The ichnofossils and rhizoliths of the Oligocene Jebel Qatrani Formation of Egypt are among the best preserved, most diverse in form, and most abundant of such structures yet recognized in fluvial rocks. Twenty-one forms are described. The ichnofauna contains traces (domichnia, fodinichnia, cubichnia) of probable annelid, insect, crustacean, and vertebrate origin. These include the first described fossil nest structures and gallery systems of subterranean termites (Isoptera), the first examples of Ophiomorpha from wholly fluvial rocks, and the first fossil vertebrate burrows from the African Tertiary. Rhizoliths associated with the ichnofauna and those occurring elsewhere document a variety of small, wetland plants, coastal mangroves, and much larger trees. The environment suggested by these traces is consistent with the coastal, tropical to subtropical, monsoonal rain forest, with adjacent more open areas, that is indicated by independent evidence of sedimentology, paleontology, and paleopedology. ?? 1982.

  8. Late Quaternary evolution of fluvial sediment composition: a modeling case study of the River Meuse

    NASA Astrophysics Data System (ADS)

    Tebbens, L. A.; Veldkamp, A.

    2000-12-01

    This paper addresses the influence of external forcing (changes in tectonics, sea level and climate) on the downstream and long-term (10 3-10 5 years) evolution of sediment composition along a fluvial longitudinal profile. The River Meuse served as a case study for a semi 2-D forward-modelling approach to simulate the downstream sediment transport in the 200- to 0-ka period. This has been related to bulk geochemical properties of the tributary catchments to quantify the bulk composition of the sediment load in the main river. The model was used to test the hypothesis that long-term fluvial dynamics influences sediment composition. The simulation exercise showed that long-term fluvial dynamics can yield systematic temporal changes in fluvial sediment composition, especially in high-relief areas. We tested a scenario of minimal discharges and maximum hillslope erosion during cold glacial periods (weathering-limited sediment supply), alternating with maximal discharges and minimal hillslope erosion during prolonged interstadials or interglacials (transport-limited sediment supply). This scenario largely reproduced the timing and direction of measured changes in the bulk and clay geochemistry of fine-grained sediments, which were deposited in the River Meuse lower reach from 13 to 0 ka. However, it failed to reproduce the measured amplitude of change, which was five to six times larger than the modelled amplitude. This suggests that climate-dependent changes in weathering intensity of rocks and saprolite in the source areas were more important and that aeolian inputs from outside the drainage basin have co-determined the sediment composition.

  9. Holocene monsoonal dynamics and fluvial terrace formation in the northwest Himalaya, India

    Microsoft Academic Search

    B. Bookhagen; D. Fleitmann; K. Nishiizumi; M. R. Strecker; R. C. Thiede

    2006-01-01

    Aluminum-26 and beryllium-10 surface exposure dating on cut-and-fill river-terrace surfaces from the lower Sutlej Valley (northwest Himalaya) documents the close link between Indian Summer Monsoon (ISM) oscillations and intervals of enhanced fluvial incision. During the early Holocene ISM optimum, precipitation was enhanced and reached far into the internal parts of the orogen. The amplified sediment flux from these usually dry

  10. Human impact on fluvial regimes and sediment flux during the Holocene: Review and future research agenda

    NASA Astrophysics Data System (ADS)

    Hoffmann, T.; Thorndycraft, V. R.; Brown, A. G.; Coulthard, T. J.; Damnati, B.; Kale, V. S.; Middelkoop, H.; Notebaert, B.; Walling, D. E.

    2010-06-01

    There is a long history of human-riverine interactions throughout the period of agriculture that in some regions of the world started several thousand years ago. These interactions have altered rivers to human dominated systems with often negative impacts on fluvial environments. To achieve a good ecological and chemical status of rivers, as intended in the European Water Framework Directive (WFD), a better understanding of the natural status of rivers and an improved quantification of human-riverine interactions is necessary. Over the last decade the PAGES-LUCIFS (Land Use and Climate Impact on Fluvial Systems) program has been investigating both contemporary and long-term (centuries to millennia) river responses to global change with the principal aims of: 1) quantifying land use and climate change impacts of river-borne fluxes of water, sediment, C, N and P; 2) identification of key controls on these fluxes at the catchment scale; and 3) identification of the feedback on both human society and biogeochemical cycles of long-term changes in the fluxes of these materials. Here, we review recent progress on identifying fluvial system baselines and quantifying the response of long-term sediment budgets, biogeochemical fluxes and flood magnitude and frequency to Holocene global change. Based on this review, we outline the future LUCIFS research agenda within the scope of the PAGES-PHAROS (Past Human-Climate-Ecological Interactions) research program. Key research strategies should be focused on: 1) synthesising the data available from existing case studies; 2) targeting research in data-poor regions; 3) integrating sediment, C, N and P fluxes; 4) quantifying the relative roles of allogenic and autogenic forcing on fluvial regimes, extreme events and sediment fluxes; 5) improving long-term river basin modelling; and 6) integration of LUCIFS with other research communities within PHAROS, namely HITE (land cover) and LIMPACS (water quality and biodiversity).

  11. Land Use and Climate Impacts on Fluvial Systems (LUCIFS): A PAGES - Focus 4 (PHAROS) research activity

    Microsoft Academic Search

    John Dearing; Thomas Hoffmann

    2010-01-01

    LUCIFS is a global research program which is concerned with understanding past interactions between climate, human activity and fluvial systems. Its focus is on evaluating the geomorphic impact of humans on landscapes, with a strong emphasis on geomorphological and sedimentological perspectives on mid- to long-term man-landscape interactions. Of particular relevance are aspects of sediment redistribution systems such as non-linear behaviour,

  12. Holocene sediment accretion in the Trinity River delta, Texas, in relation to modern fluvial input

    Microsoft Academic Search

    Michael C. Slattery; Lee M. Todd; Jonathan D. Phillips; John A. Breyer

    2010-01-01

    Purpose  This study uses sediment cores to quantify Holocene sedimentation rates in the Trinity River delta, Texas. An important question\\u000a is whether modern fluvial sediment input from the Trinity River is adequate to sustain sedimentation in the delta, thereby\\u000a combating subsidence and further wetland loss. Our objective was to quantify sedimentation rates within the delta in order\\u000a to assess whether the

  13. Applicability of Complexity Theory to Martian Fluvial Systems: A Preliminary Analysis

    NASA Technical Reports Server (NTRS)

    Rosenshein, E. B.

    2003-01-01

    In the last 15 years, terrestrial geomorphology has been revolutionized by the theories of chaotic systems, fractals, self-organization, and selforganized criticality. Except for the application of fractal theory to the analysis of lava flows and rampart craters on Mars, these theories have not yet been applied to problems of Martian landscape evolution. These complexity theories are elucidated below, along with the methods used to relate these theories to the realities of Martian fluvial systems.

  14. Fluvial development of major Alpine valleys since the mid-Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Leith, Kerry; Fox, Matthew; Moore, Jeffrey R.

    2015-04-01

    The effects of both fluvial and glacial processes are evident in the morphology of bedrock hillslopes and river channels throughout the European Alps. While steep rock slopes in upper, U-shaped reaches of valleys provide clear evidence for a Pleistocene history that includes at least one period of major glacial erosion, river channels near the toe of blocky rock slopes in lower, V-shaped reaches suggest fluvial incision has played an important role in Alpine evolution. In order to differentiate the impact of these two process regimes on the development of the orogen, we use a combination of integral analysis and forward streampower models to identify a series of corresponding steepened channel reaches across a relatively homogeneous tectonic block of the southern Swiss Alps. We consider these steepened channel sections represent up to seven knickpoints that extend 800 m above the elevation of the present-day Rhone Valley. The uppermost (oldest) knickpoint is currently located approximately half-way into each valley, and effectively defines the front of fluvial erosion into a relict glacial landscape preserved in the upper reaches of each catchment. We expect that these knickpoints form near the outlet of tributary valleys as a result of bedrock uplift during major glacial cycles. The knickpoints are exposed during deglaciation, and propagate upstream as in response to increased streampower during major Pleistocene interglacials. By employing a forward streampower incision model regulated by the timing of global marine isotope stages we are able to reproduce both the form, and location of knickpoints across our study region, and correlate distinct breaks in cross-sectional valley slope to discrete glacial - interglacial transitions. Our results indicate that Alpine landscape evolution has been driven by a combination of tectonic uplift and fluvial incision since an initial period of enhanced glacial erosion prior to 0.7 Ma. We find that rates of tectonic uplift have been relatively consistent since this time, while transitional landscape forms have been largely preserved throughout each glacial cycle.

  15. The use of sediments to detect human impact on the fluvial system

    Microsoft Academic Search

    G. F. Birch; E. Robertson; S. E. Taylor; D. M. McConchie

    2000-01-01

    Sediments have been used to detect sources of contamination in a catchment of the Port Jackson (Sydney Harbour) estuary and\\u000a to evaluate the effects of different land-use practices on the fluvial environment. Mean enrichment (mean concentrations over\\u000a pre-anthropogenic background) of size-normalized (<62.5??m) aquatic sediment is 10 × for Cu, 20× for Pb and 90× for Zn adjacent\\u000a to industrialized areas

  16. Heterogeneity in a Suburban River Network: Understanding the Impact of Fluvial Wetlands on Dissolved Oxygen and Metabolism in Headwater Streams

    NASA Astrophysics Data System (ADS)

    Cain, J. S.; Wollheim, W. M.; Sheehan, K.; Lightbody, A.

    2014-12-01

    Low dissolved oxygen content in rivers threatens fish populations, aquatic organisms, and the health of entire ecosystems. River systems with high fluvial wetland abundance and organic matter, may result in high metabolism that in conjunction with low re-aeration rates, lead to low oxygen conditions. Increasing abundance of beaver ponds in many areas may exacerbate this phenomenon. This research aims to understand the impact of fluvial wetlands, including beaver ponds, on dissolved oxygen (D.O.) and metabolism throughout the headwaters of the Ipswich R. watershed, MA, USA. In several fluvial wetland dominated systems, we measured diel D.O. and metabolism in the upstream inflow, the surface water transient storage zones of fluvial wetland sidepools, and at the outflow to understand how the wetlands modify dissolved oxygen. D.O. was also measured longitudinally along entire surface water flow paths (x-y km long) to determine how low levels of D.O. propagate downstream. Nutrient samples were also collected to understand how their behavior was related to D.O. behavior. Results show that D.O. in fluvial wetlands has large swings with periods of very low D.O. at night. D.O. swings were also seen in downstream outflow, though lagged and somewhat attenuated. Flow conditions affect the level of inundation and the subsequent effects of fluvial wetlands on main channel D.O.. Understanding the D.O. behavior throughout river systems has important implications for the ability of river systems to remove anthropogenic nitrogen.

  17. Magnetic Properties of a Fluvial Chronosequence From the Eastern Wind River Range, Wyoming

    NASA Astrophysics Data System (ADS)

    Quinton, E. E.; Dahms, D. E.; Geiss, C. E.

    2010-12-01

    In order to constrain the rate of magnetic enhancement in glacial fluvial sediments, we sampled modern soils from eight fluvial terraces in the East Wind River Range in Wyoming. Soil profiles up to 1.2 meters deep were described in the field and sampled in five cm intervals from a series of hand-dug pits or natural river-bank exposure. The age of the studied profiles are estimated to range from >600 ka to modern. They include Sacagawea Ridge, Bull Lake and Pinedale-age fluvial terraces as well as one Holocene profile. To characterize changes in magnetic properties we measured low-field magnetic susceptibility, anhysteretic remanent magnetization, isothermal remanent magnetization and S-ratios for all, and hysteresis loops for a selected sub-set of samples. Our measurements show no clear trend in magnetic enhancement with estimated soil age. The observed lack of magnetic enhancement in the older soils may be due to long-term deflation, which continuously strips off the magnetically enhanced topsoil. It is also possible that the main pedogenic processes, such as the development of well-expressed calcic horizons destroy or mask the effects of long-term magnetic enhancement.

  18. Fractal topography and subsurface water flows from fluvial bedforms to the continental shield

    USGS Publications Warehouse

    Worman, A.; Packman, A.I.; Marklund, L.; Harvey, J.W.; Stone, S.H.

    2007-01-01

    Surface-subsurface flow interactions are critical to a wide range of geochemical and ecological processes and to the fate of contaminants in freshwater environments. Fractal scaling relationships have been found in distributions of both land surface topography and solute efflux from watersheds, but the linkage between those observations has not been realized. We show that the fractal nature of the land surface in fluvial and glacial systems produces fractal distributions of recharge, discharge, and associated subsurface flow patterns. Interfacial flux tends to be dominated by small-scale features while the flux through deeper subsurface flow paths tends to be controlled by larger-scale features. This scaling behavior holds at all scales, from small fluvial bedforms (tens of centimeters) to the continental landscape (hundreds of kilometers). The fractal nature of surface-subsurface water fluxes yields a single scale-independent distribution of subsurface water residence times for both near-surface fluvial systems and deeper hydrogeological flows. Copyright 2007 by the American Geophysical Union.

  19. Assesing Hydrophysical/Enivornmenal impacts by Dams in the Amazon (fluvial) Basin

    NASA Astrophysics Data System (ADS)

    Wight, C.; Latrubesse, E. M.

    2014-12-01

    Growing demands from human activities are increasing the pressure and impacts on the Amazon River basin. Covering almost 40% of South America, the Amazon River basin's health is of global importance. With tributaries in 6 different countries, the anthropogenic impacts on this large system are complex and hard to synthesize. However to better understand large system responses to human impacts such an analysis is called for. Our objective is to organize a rigorous analysis of the potential hydro-physical impacts of dams on the major sub-basins of the Amazon. We are incorporating existing data of sediment fluxes, deforestation and land-use land-change to include the entire extent of the basin as defined by the fluvial unit. In addition, we will be analyzing the spatial distributions of dams (planned, under construction, and constructed) within each sub-basin. Our preliminary results have used statistical analysis and remote sensing to calculate the extent of deforestation on fluvial regimes of the legal Amazon and concentrated to identify the potential disruptions of sediment fluxes. Combining the spatial distributions of dam sites, and deforestation per sub-basin we will develop a system to interpret land-use and land-change per catchment. This in turn will allow us to better predict changes in the fluvial regimes and allow for comparisons of vulnerability.

  20. Fluvial drainage systems: Margaritifer Sinus and Agyre (NC, NE) quadrangles, Mars

    NASA Technical Reports Server (NTRS)

    Boothroyd, J. C.; Grant, J. A.

    1984-01-01

    Fluvial drainage systems, delineated by mapping on stereo pairs of Viking Orbiter images, have developed in various-sized basins in the Margaritifer Sinus (MC-19) and Agyre (MC-26) Quadrangles, Mars. The Ladon Valles system is the largest, draining into and through two multi-ringed impact basins. Smaller fluvial basins to the southeast of the Ladon structural basin appear to have internal drainage. An intermediate-scale fluvial basin containing Himera Vallis extends along a north-south axis at 22 W and opens northward toward outflow channels south of Margaritifer Chaos. Stereo-pair mapping was extended furhter to the east, in MC-19 Ne, Se, and MC-26 NE, to investigate sources of outflow to the Ares Vallis system. The direction of flow in the channel at the northeast quadrant of the Ladon Basin is unresolved at present because of the poor quality of images available to form stereo pairs. However, an easterly drainage basin boundary running north-south along longitude 9 W, and extending westward at latitude 32-35 S, encloses a series of longitudinal drainage systems. Both the Parana Valles-Loire Vallis system and the Samara Valles system appear to drain in a northwesterly direction. The Samara flows to the Himera drainage basin, and the Parana-Loire to the northeast Ladon channel area.

  1. Segmentação, Indexação e Recuperação de Vídeo Utilizando OpenCV

    Microsoft Academic Search

    Thiago Teixeira Santos; Carlos Hitoshi Morimoto

    Resumo: Os constantes avanços em poder de processamento, capacidade de armazenamento, e largura de banda tornaram possível ao usuário de com- putadores o acesso, manipulação e edição de imagens e vídeos digitais. Nesse tutorial, vamos descrever alguns algoritmos de visão computacional para a seg- mentação, indexação e recuperação de vídeo utilizando o OpenCV para que, ao final do tutorial, você

  2. Fluvial Interpretation of Ridged Units, Northern Sinus Meridiani/Southwest Arabia Terra, Mars

    NASA Astrophysics Data System (ADS)

    Wilkinson, J.; Allen, C. C.; Oehler, D. Z.

    2007-12-01

    THEMIS, MOC, and HiRISE imagery shows features at various scales that suggest fluvial emplacement of the ridge-forming rock units exposed in northern Sinus Meridiani and southwestern Arabia Terra. The study area -- 10 N to 2 S latitude and 10 W to 8 E longitude -- spans the interface from the southern highlands to the northern plains. Numerous, linear ridges of varying width, orientation and sinuosity (mainly lower sinuosity) are suggestive of fluvial channels. Sets of features can be interpreted as braided channel reaches. Cross-cutting relationships, a common feature of channels on terrestrial fluvial plains, are ubiquitous. Many sinuous features appear as twinned parallel lines, suggesting preferential cementing of coarser channel-bank sediments. A few examples exist of features that can be interpreted as scroll bars and channel augmentation in locally narrow reaches. Layering and internal discontinuities of the Meridiani rocks are consistent with a fluvial interpretation. The regional setting of study-area units accords closely with many terrestrial basins which are occupied by fluvially emplaced sediment bodies known as megafans. Contiguous megafan surfaces (characterized by numerous channel traces, of varied orientation) cover large areas -- 1.25 million sq. km. in S. America -- with radii of hundreds of km. Megafans characteristically lie at the foot of a backing highland, from which rivers supply sediment. The ridged units on Mars lie at the foot of the southern highlands from which numerous river valleys have drained towards Meridiani Planum/southwest Arabia Terra. Further, the present regional slope is apparently away from the highlands, with downslope dimensions of hundreds of km. The low slopes of the northern Meridiani units mirror the typically low regional slopes of terrestrial megafans. Low slopes are conducive to the development of water bodies, which are numerous on some terrestrial megafans. The lacustrine model for the formation of the hematite-bearing unit is thus consistent with a megafan analog. Eroded desert landscapes on Earth show chemically cemented paleo-channels as inverted topography. Paleo- megafans in terrestrial deserts, displaying inverted topography, are the closest morphologic analogs to the ridges of northern Meridiani/southwest Arabia Terra. Further studies -- including quantitative comparisons of ridge characteristics and spectroscopic investigation of cementing minerals -- are underway to determine the origin of these widespread martian units.

  3. Characterisation of the sedimentary processes responsible for the filling and excavation of two intra mountainous basins (Agua Amarga and Collon Cura) in the Andes of Neuquén (Argentina) during the Neogene

    NASA Astrophysics Data System (ADS)

    Bonnel, C.; Huyghe, D.; Nivière, B.; Messager, G.; Dhont, D.; Fasentieux, B.; Hervouët, Y.; Xavier, J.-P.

    2012-04-01

    Intramontane basins constitute potential good recorders of orogenic systems deformation history through the documentation of their remnant sedimentary filling and observation of syntectonic growth strata. In this work, we focus on the Neuquén basin, located on the eastern flank of the Andes between 32°S and 41°S latitude. It has been structured since the late Triassic, first as back arc basin and as compressive foreland basin since the upper Cretaceous. Most of the sedimentary filling is composed of Mesozoic sediments, which have been importantly studied because of their hydrocarbon potential. On the contrary, Cenozoic tectonic and sedimentologic evolutions remain poorly documented in regard to the Mesozoic. The structural inheritance is very important and strongly influences the deformation and shortening rates from the North to the South of the basin. Thus, the northern part exhibits a classical configuration from the western high Andes, to younger fold and thrust belts and piggy-back basins to the East. On the contrary, no fold and thrust belt exist in the southern part of the basin and the deformation is restricted to the internal domain. Nevertheless, contemporaneous intramontane basins (the Agua Amarga to the North and the Collon Cura basin to the South) existed in these two parts of the basin and seem to have followed a similar evolution despite of a different structural context. To the North, the partial closing of the Agua Amarga basin by the growth of the Chuihuidos anticlines during the Miocene is characterised by the deposition of a fining upward continental sequence of ~250 m thick, from lacustrine environment at the base to alluvial and fluviatile environments in the upper part of the section. In the Collon Cura, the sedimentary filling, due to the rising of the Piedra del Aguila basement massif, reach at maximum 500 m and consist in fluvial tuffaceous material in the lower part to paleosoils and coarse conglomeratic fluvial deposits in the upper part. To the North, excavation of the Agua Amarga basin happened after regressive erosion on the external flank of the Chuihuidos anticlines and generated the deposition of an alluvial fan of 50 km length and maximum thickness of 140 m. Concerning the South, the paleolandscape conditioned the deposition of a very long (~ 20 km) but very narrow (few tens of kilometres) alluvial fan. The excavation is the consequence of the elevation cessation of the Piedra del Aguila basement.

  4. Facies architecture and sequence stratigraphy of an early post-rift fluvial succession, Aptian Barbalha Formation, Araripe Basin, northeastern Brazil

    NASA Astrophysics Data System (ADS)

    Scherer, Claiton M. S.; Goldberg, Karin; Bardola, Tatiana

    2015-06-01

    The Barbalha Formation (Aptian) records deposition in a fluvial and lacustrine environment accumulated in an early post-rift sag basin. Characterization of the facies architecture and sequence stratigraphic framework of the alluvial succession was carried out through detailed description and interpretation of outcrops and cored wells. The development of depositional sequences in this unit reflects variation in the accommodation-to-sediment supply (A/S) ratio. Two depositional sequences, showing an overall fining-upward trend, are preserved within the succession. The sequences are bounded by regional subaerial unconformities formed during negative A/S ratio, and may be subdivided in Low-accommodation Systems Tracts (LAST) (positive A/S ratio close to zero) and High accommodation Systems Tracts (HAST) (A/S ratio between 0.5 and 1). Sequence 1, with a minimum thickness of 100 m, is characterized by amalgamated, multi-storey, braided fluvial channel sand bodies, defining a LAST. These are interlayered with crevasse splay and floodplain deposits toward the top, passing to open lacustrine deposits, defining a HAST. Sequence 2, with minimum thickness ranging from 50 to 90 m, overlies the organic-rich lacustrine deposits. At the base, this sequence is composed of amalgamated, multistorey braided fluvial channel sand bodies (LAST), similar to Sequence 1, overlain by well-drained floodplain with fixed fluvial channel deposits, interpreted as an anastomosed fluvial system, which are in turn capped by lacustrine deposits, both grouped in a HAST. Paleocurrent data on fluvial deposits of sequences 1 and 2 show a consistent paleoflow to the SE. Sedimentological evidence indicates humid to sub-humid climatic conditions during deposition of sequences 1 and 2. Accumulation of fluvial sequences 1 and 2 was mainly controlled by tectonics. Variation in A/S ratios must be related to tectonic subsidence and uplift of the basin.

  5. Investigation of fluvial landforms in the north-eastern Pannonian Basin, using cartographic materials from the XIX-XXI Centuries

    NASA Astrophysics Data System (ADS)

    Robu, Delia; Niga, Bogdan; Per?oiu, Ioana

    2015-04-01

    The study area is located in the north-eastern Pannonian Basin, and covers approximately 3700 km2. Using cartographic materials for the last 155 years, we analyzed and defined river network and relict fluvial morphologies created by the rivers Tur, Some?, Homorod and Crasna. Database extraction from each set of historical maps was performed by field verification and validation, associated to GIS techniques. Relict fluvial morphologies on the Some? alluvial cone comprise a wide variety of channel typologies and sizes, drainage directions and their consequent typology, which indicates a complex fluvial evolution. The dominant category of relict fluvial morphology is represented by the meander loop. Following the quantitative analysis on the successive sets of maps we identified and delimited meander loops and meandering paths formed prior to the reference year 1860. Generally, the post-1860 relict fluvial morphologies are secondary morphologies, as the keynote is given by those formed previous to the reference moment 1860. An analysis of the share of the relict fluvial morphologies on the three sets of reference cartographic materials (the second Austro-Hungarian topographic survey, Google Earth and orthophotoplans) highlights that most relict fluvial morphologies were identified on the second Austro-Hungarian topographic survey, followed by those identified in Google Earth and orthophotoplans. The map of fluvial morphologies constructed in this study enables a discussion on drainage directions, based on the observation that a series of abandoned meander loops and segments follow clear directions. We applied several quantitative indices in assessing the relict fluvial morphology (radius of curvature, paleochannel width). Consequently, we identified underfit stream sectors with meander loops larger than the modern ones Some? meanders (on the Racta River), uncharacteristic features such as braided riverbed reaches, a high frequency of meander scrolls present on the right bank of Crasna at its entrance in the plain, or the occurrence of wetlands in an area affected by subsidence (the Ecedeea Plain). Despite the ample human intervention in our study area through sewers, dams, meander cuts, the river network evolution trend remained the same between 1860 and 2005, with evolution and formation of meanders, although the change rate has diminished. "ACKNOWLEDGMENT This paper has been financially supported within the project entitled "SOCERT. Knowledge society, dynamism through research", contract number POSDRU/159/1.5/S/132406. This project is co-financed by European Social Fund through Sectoral Operational Programme for Human Resources Development 2007-2013. Investing in people!"

  6. Fluvial and glacial implications of tephra localities in the western Wind River basin, Wyoming, U. S. A

    SciTech Connect

    Jaworowski, C. (Univ. of Wyoming, Laramie, WY (United States). Dept. of Geology)

    1993-04-01

    Examination of Quaternary fluvial and glacial deposits in the western Wind River Basin allows a new understanding of the Quaternary Wind River fluvial system. Interbedded fluvial sediments and volcanic ashes provide important temporal information for correlation of Quaternary deposits. In the western Wind River Basin, six mid-Pleistocene localities of tephra, the Muddy Creek, Red Creek, Lander, Kinnear, Morton and Yellow Calf ashes are known. Geochronologic studies confirm the Muddy Creek, Red Creek, Kinnear and Lander ashes as the 620--650ka Lava Creek tephra from the Yellowstone region in northwestern Wyoming. The stratigraphic position and index of refraction of volcanic glass from the Morton and Yellow Calf ashes are consistent with identification as Lava Creek tephra. Approximately 350 feet (106 meters) above the Wind River and 13 miles downstream from Bull Lake, interbedded Wind River fluvial gravels, volcanic glass and pumice at the Morton locality correlate to late (upper) Sacajawea Ridge gravels mapped by Richmond and Murphy. Associated with the oxygen isotope 16--15 boundary, the ash-bearing terrace deposits reveal the nature of the Wind River fluvial system during late glacial-early interglacial times. The Lander and Yellow Calf ashes, are found in terrace deposits along tributaries of the Wind River. Differences in timing and rates of incision between the Wind River and its tributary, the Little Wind River, results in complex terrace development near their junction.

  7. Classification of biological and non-biological fluvial particles using image processing and artificial neural network

    NASA Astrophysics Data System (ADS)

    Shrestha, Bim Prasad; Shrestha, Nabin Kumar; Poudel, Laxman

    2009-04-01

    Particles flowing along with water largely affect safe drinking water, irrigation, aquatic life preservation and hydropower generation. This research describes activities that lead to development of fluvial particle characterization that includes detection of biological and non-biological particles and shape characterization using Image Processing and Artificial Neural Network (ANN). Fluvial particles are characterized based on multi spectral images processing using ANN. Images of wavelength of 630nm and 670nm are taken as most distinctive characterizing properties of biological and non-biological particles found in Bagmati River of Nepal. The samples were collected at pre-monsoon, monsoon and post-monsoon seasons. Random samples were selected and multi spectral images are processed using MATLAB 6.5. Thirty matrices were built from each sample. The obtained data of 42 rows and 60columns were taken as input training with an output matrix of 42 rows and 2 columns. Neural Network of Perceptron model was created using a transfer function. The system was first validated and later on tested at 18 different strategic locations of Bagmati River of Kathmandu Valley, Nepal. This network classified biological and non biological particles. Development of new non-destructive technique to characterize biological and non-biological particles from fluvial sample in a real time has a significance breakthrough. This applied research method and outcome is an attractive model for real time monitoring of particles and has many applications that can throw a significant outlet to many researches and for effective utilization of water resources. It opened a new horizon of opportunities for basic and applied research at Kathmandu University in Nepal.

  8. Fluvial particle characterization using artificial neural network and spectral image processing

    NASA Astrophysics Data System (ADS)

    Shrestha, Bim Prasad; Gautam, Bijaya; Nagata, Masateru

    2008-03-01

    Sand, chemical waste, microbes and other solid materials flowing with the water bodies are of great significance to us as they cause substantial impact to different sectors including drinking water management, hydropower generation, irrigation, aquatic life preservation and various other socio-ecological factors. Such particles can't completely be avoided due to the high cost of construction and maintenance of the waste-treatment methods. A detailed understanding of solid particles in surface water system can have benefit in effective, economic, environmental and social management of water resources. This paper describes an automated system of fluvial particle characterization based on spectral image processing that lead to the development of devices for monitoring flowing particles in river. Previous research in coherent field has shown that it is possible to automatically classify shapes and sizes of solid particles ranging from 300-400 ?m using artificial neural networks (ANN) and image processing. Computer facilitated with hyper spectral and multi spectral images using ANN can further classify fluvial materials into organic, inorganic, biodegradable, bio non degradable and microbes. This makes the method attractive for real time monitoring of particles, sand and microorganism in water bodies at strategic locations. Continuous monitoring can be used to determine the effect of socio-economic activities in upstream rivers, or to monitor solid waste disposal from treatment plants and industries or to monitor erosive characteristic of sand and its contribution to degradation of efficiency of hydropower plant or to identify microorganism, calculate their population and study the impact of their presence. Such system can also be used to characterize fluvial particles for planning effective utilization of water resources in micro-mega hydropower plant, irrigation, aquatic life preservation etc.

  9. Analysis on the Characteristics of Fluvial Evolution with Climate Changes from Numerical Simulation

    NASA Astrophysics Data System (ADS)

    Yan, Zhenzhen

    2014-05-01

    Landform evolution is one part of the Earth system behaviors. Products from the landform evolution are faithful records for the global change. They are created by complex interaction between geomorphic processes and environmental factors, and be able to provide the most important and intuitive evidences for investigating the interaction between the Earth's tectonic processes and climate changes. Because of very limited geodetic and geological data, we need a profound understanding of how landscapes respond and erode in response to changes in tectonic or climate boundary conditions. Quantitative study on landform evolution in different spatial and temporal scales using numerical simulation has important scientific interest and practical significance for investigating the nonlinear coupling relationship and response mechanism between tectonic activity, climate change, and surface processes. Under background of the global climate change, rivers have been a major focus of research in landform evolution because they are patently sensitive to tectonic and climate forcing via their channel characteristics. According to the existing research on the channel profiles, in this study, we employ numerical method incorporated with remote sensing techniques to investigate the surface process response to climate-tectonic-landscape through analysis and verification exploration. We build a numerical model based on the theory of geomorphic evolution, and take study on dynamical processes of the channel profile evolution with tectonic and climate boundary. Primary simulation results show that the linear diffusion is not enough to demonstrate the whole evolution. The analyses show that erosion plays a major role in fluvial evolution. Analysis on the dynamic processes of fluvial evolution, clarification its morphological characteristics, and exploration its formation and evolution is helpful for thorough study and understanding the relationship between the various factors of fluvial evolution system, and making forecast for future significant changes in the system with global changes.

  10. The legacy of impact conditions in morphometrics of percussion marks on fluvial bedrock surfaces

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew; Lavé, Jérôme

    2013-03-01

    Percussion, or impact, marks are a common type of bedrock bedform found on many fluvial bedrock channels and have been attributed to bedload impact. Little is known about the conditions under which they form and how these affect morphology and dimensions of impact mark craters. We present data from a set of experiments exploring the formation of percussion marks by bedload impact under controlled conditions (impact velocity, angle, and particle diameter) by quartz spheres onto polished marble plates through a water interface. Particle impact causes impact craters consisting of a central depressed pit and a surrounding raised crater rim under all impact conditions. Data from 699 impact experiments show that crater rims are always circular and crater diameter (?c, in m) scales with the kinetic energy of the particle normal to the surface immediately prior to impact (K.E., in J) by the relationship K.E. = 2.48 × 107?c3.188. We test this relationship on impact marks produced in a series of controlled flume experiments for a range of surface inclinations found in natural fluvial channel outcrops. Measurements of impact crater diameter were used to estimate K.E. using our empirical equation. Our model estimates very similar K.E. for impact craters produced in this quasinatural setting to those calculated from flume conditions when realistic values for mean impact velocity and mean impact angle are assumed. Applying this relationship to measurements of crater rim diameter in natural settings will allow the mapping of impact K.E. along and across channel reaches where these bedforms are found. Future numerical models of fluvial bedrock erosion based on impact K.E. could be field calibrated from measurements of percussion marks in marble channels or from installed marble slabs in other bedrock channel reaches.

  11. Human impacts on headwater fluvial systems in the northern and central Andes

    NASA Astrophysics Data System (ADS)

    Harden, Carol P.

    2006-09-01

    South America delivers more freshwater runoff to the ocean per km 2 land area than any other continent, and much of that water enters the fluvial system from headwaters in the Andes Mountains. This paper reviews ways in which human occupation of high mountain landscapes in the Andes have affected the delivery of water and sediment to headwater river channels at local to regional scales for millennia, and provides special focus on the vulnerability of páramo soils to human impact. People have intentionally altered the fluvial system by damming rivers at a few strategic locations, and more widely by withdrawing surface water, primarily for irrigation. Unintended changes brought about by human activities are even more widespread and include forest clearance, agriculture, grazing, road construction, and urbanization, which increase rates of rainfall runoff and accelerate processes of water erosion. Some excavations deliver more sediment to river channels by destabilizing slopes and triggering processes of mass-movement. The northern and central Andes are more affected by human activity than most high mountain regions. The wetter northern Andes are also unusual for the very high water retention characteristics of páramo (high elevation grass and shrub) soils, which cover most of the land above 3000 m. Páramo soils are important regulators of headwater hydrology, but human activities that promote vegetation loss and drying cause them to lose water storage capacity. New data from a case study in southern Ecuador show very low bulk densities (median 0.26 g cm - 3 ), high organic matter contents (median 43%), and high water-holding capacities (12% to 86% volumetrically). These data document wetter soils under grass than under tree cover. Effects of human activity on the fluvial system are evident at local scales, but difficult to discern at broader scales in the regional context of geomorphic adjustment to tectonic and volcanic processes.

  12. Fluvial sedimentology of a Mesozoic petrified forest assemblage, Shishu Formation, Junggar foreland basin, Xinjiang, China

    SciTech Connect

    McKnight, C.L.; Gan, O.; Carroll, A.R.; Dilcher, D.; Zhao, M.; Liang, Y.H.; Graham, S.A.

    1988-02-01

    The Upper Jurassic(.) Shishu Formation of the eastern Junggar basin, Xinjiang, northwest China, is a fluvial sand unit containing an important assemblage of well-preserved, silicified tree trunks and rooted stumps. Numerous logs, up to 83 ft (25.5 m) long, occur at several levels within a 33.6-ft (10.3 m) stratigraphic section of fluvial sand, gravel, and mud and several paleosol horizons. The uppermost logbearing layer includes a number of rooted tree stumps in growth position, with diameters of up to 8 ft (2.5 m). The maximum root length observed is 40 ft (12.3 m). The trees have been identified by Chinese paleontologists as Cupressinoxylon. The petrified forest assemblage is preserved on the northeast margin of the Mesozoic Junggar foreland basin, a large continental basin subsiding under thrust loading from the south. Logs found within channel gravel units are oriented with their log axes parallel to the channel axis. Sedimentary structures, including epsilon and trough cross-stratification and imbricated channel gravels, indicate paleocurrent flow generally to the south, toward the basin center. The size of the logs suggests the presence of a major fluvial system. The epsilon cross-sets suggest a channel depth of 26 ft (8 m). The oriented silicified logs and their enclosing clastic sediments provide important information on the depositional systems active on the northeastern margin of the Junggar basin in the Late Jurassic(.) time. Hopefully, further detailed study of the fossil trees, including the spacing of the rooted stumps, will provide new information on the paleoecology of Mesozoic forests and the climatic conditions prevailing in the region at the time of deposition.

  13. Fluvial Erosion Measurements of Streambank Using Photo-Electronic Erosion Pins (peep)

    NASA Astrophysics Data System (ADS)

    Sutarto, T.; Papanicolaou, T.; Wilson, C. G.; Bertrand, F.

    2010-12-01

    Cohesive streambank erosion is characterized by two main mechanisms, fluvial entrainment of individual particles and bank failure due to gravity (Thorne, 1980). In this study, the relative importance of fluvial erosion (compared to mass failure) was determined in two reaches from different locations of the Clear Creek Watershed (CCW). The main goal of the project was the identification of the key erosion process at each site. Beyond the distinguished flow conditions (hydraulic forces), different stream orders, and land-use, no further attempts were made to identify other key driving agents behind the erosion, such subaerial processes (e.g., seepage, freeze/thaw) acting at the cohesive riverbanks (Lindow et al., 2009). Erosion lengths up to 38 cm were detected. The bank erosion monitoring at high resolution intervals due to the PEEPS allowed for better characterization the fluvial erosion occurring at this site and develop a correspondence between sedigraphs and hydrographs. .Similar statistical methods were used at both sites to support our findings. The moving average identified the dominant trend of the data and the variability of the erosion lengths at the two sites. Further, the use of the Shewhart Charts allowed us to detect the critical erosion events during the period of observation. Finally the overall performance of the PEEPs was evaluated during this study. A correlation analysis was conducted between the direct measurements of traditional methods (e.g., erosion pins, geodetical surveys, measure tape) and the automated data recorded by the PEEP. The maximum error between manual and automated measurements of the exposed length of the PEEPs was less than 27%. The error between the channel survey and the automated PEEP measurements was less than 14%.

  14. Quantifying fluvial topography using UAS imagery and SfM photogrammetry

    NASA Astrophysics Data System (ADS)

    Woodget, Amy; Carbonneau, Patrice; Visser, Fleur; Maddock, Ian; Habit, Evelyn

    2014-05-01

    The measurement and monitoring of fluvial topography at high spatial and temporal resolutions is in increasing demand for a range of river science and management applications, including change detection, hydraulic models, habitat assessments, river restorations and sediment budgets. Existing approaches are yet to provide a single technique for rapidly quantifying fluvial topography in both exposed and submerged areas, with high spatial resolution, reach-scale continuous coverage, high accuracy and reasonable cost. In this paper, we explore the potential of using imagery acquired from a small unmanned aerial system (UAS) and processed using Structure-from-Motion (SfM) photogrammetry for filling this gap. We use a rotary winged hexacopter known as the Draganflyer X6, a consumer grade digital camera (Panasonic Lumix DMC-LX3) and the commercially available PhotoScan Pro SfM software (Agisoft LLC). We test the approach on three contrasting river systems; a shallow margin of the San Pedro River in the Valdivia region of south-central Chile, the lowland River Arrow in Warwickshire, UK, and the upland Coledale Beck in Cumbria, UK. Digital elevation models (DEMs) and orthophotos of hyperspatial resolution (0.01-0.02m) are produced. Mean elevation errors are found to vary somewhat between sites, dependent on vegetation coverage and the spatial arrangement of ground control points (GCPs) used to georeference the data. Mean errors are in the range 4-44mm for exposed areas and 17-89mm for submerged areas. Errors in submerged areas can be improved to 4-56mm with the application of a simple refraction correction procedure. Multiple surveys of the River Arrow site show consistently high quality results, indicating the repeatability of the approach. This work therefore demonstrates the potential of a UAS-SfM approach for quantifying fluvial topography.

  15. Depositional controls in a bedload-dominated fluvial system: internal architecture of the Lee Formation, Kentucky

    NASA Astrophysics Data System (ADS)

    Wizevich, Michael C.

    1993-05-01

    Sandstones of the early Pennsylvanian Lee Formation, central Appalachian foreland basin, were deposited in a low-sinuosity, bedload-dominated fluvial system. The internal architecture of the sandstones consists of a six-fold hierarchy of bounding surfaces, which are evaluated with respect to depositional controls. Minor (first-, second- and third-order) surfaces, generally less than a few hundred meters in extent, separate deposits of small- to intermediate-scale bedforms. Third-order surfaces, which dip gently in the downflow direction represent reactivation surfaces of downstream-accreting macroforms. Major surfaces (fourth-, fifth- and sixth-order) are hundreds of meters to kilometers in extent. Fourth-order surfaces separate deposits of individual macroforms. Fifth-order bounding surfaces are erosional boundaries of major (system-scale) channels. Individual sandstone members of the Lee Formation are bound by sixth-order surfaces, erosional at the base and gradational at the top. Deposits overlying major surfaces contain fining-upward sequences. The trends are more apparent with increased scale of the deposit. These sequences represent responses of the fluvial system to various mechanisms that controlled sedimentation. Both fourth- and fifth-order surfaces are interpreted as results of autocyclic controls. The nature of the Lee Formation fluvial system was such that a solitary major channel was relatively stable in one position within the alluvial plain for a significant period of time. During this time the channel aggraded with the passage of one or more downstream-accreting macroforms, creating a fourth-order erosional surface. The channel eventually diverted its flow to another portion of the alluvial plain by avulsion, creating a fifth-order surface. A gross fining-upward trend and upward change in fluvial style for individual sandstone members, both characteristic of paleovalley fills, indicate that sixth-order surfaces were controlled by allocyclic processes. These characteristics and the stair-step positioning of the sandstone members (younger away from the Alleghenian Mountains to the east), suggest that tectonic processes were the ultimate control on the system.

  16. Hydrological and sedimentological regime of lower Vistula fluvial lakes (North Central Poland)

    NASA Astrophysics Data System (ADS)

    Kordowski, Jaros?aw; Kubiak-Wójcicka, Katarzyna; Tyszkowski, Sebastian; Solarczyk, Adam

    2015-04-01

    Regarding the outflow the Vistula River is the largest river in the Baltic catchment. In its lower course it has developed an anastomosing channel pattern modified strongly by intensive human hydrotechnical activity and by the regulation which have intensified about 200 years ago. Channel regulation apart from already existing lakes have left many new artificially created ones. This activity have also altered the hydrological and sedimentary regime. It turned out that only the small portion of the lakes infilled rapidly but the majority have persisted to present day almost unchanged in spite of regulation. The reason of this resistence to silting is connected with specific interaction of sediment removing during high flood water episodes and strong groundwater circulation in former river arms transformed in present-day lakes. As an example of a lake with an intensive groundwater exchange rate with the main Vistula channel and supposed Quaternary and Tertiary aquifers was selected the Old Vistula lake (Stara Wis?a) near Grudzi?dz town. It has got an area of 50 ha, mean depth 1,73 m, maximum depth 8 m, length about 4 km and medium width about 100 m. In the years 2011-2015 in its surficial water were conducted measures with two weeks frequency which included: temperature, pH, Eh, suspended matter amount, total and carbonaceous mineralization. For comparison similar measurements were also conducted in other fluvial lakes and Vistula tributaries. Hydrological data were supplemented by geological investigations of floodplain sediments cover which has important impact on the rate of groundwater migration and circulation. Investigations carried proved that there exists distinct gradient of carbonaceous mineralization from small values in the Vistula channel to high values at the valley edges. PH and Eh parameters in the Old Vistula lake were different than in all other surveyed sites what leads to conclusion that it is fed by deeper groundwaters than in the case of other fluvial lakes and Vistula tributaries, particularly in low water stand times. This is because it has not continuous flood sediments cover on its floor. The sediments accumulated during the low stands of water are removed from fluvial lakes while high stands by flood waters. Temporarily deposited sediment is also removed due to high groundwater "exchange" rate when the fluvial lake has a sufficient hydrological connectivity to the main Vistula channel. Acknowledgements: This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution (ICLEA) of the Helmholtz Association.

  17. Geomorphological facies reconstruction of Late Quaternary alluvia by the application of fluvial architecture concepts

    NASA Astrophysics Data System (ADS)

    Houben, Peter

    2007-04-01

    This paper investigates the methodical implications, the benefits, and the constraints of applying the fluvial architecture concept to Late Quaternary shallow-subsurface alluvial deposits. The focus is upon a typical small- to mesoscale valley floor of the temperate zone. The studied reach is part of the river Wetter catchment (517 km 2) in central Germany. A large number of studies on Late Quaternary terrestrial paleoenvironmental change of the temperate zone refer to such small- to mesoscale catchments, which are mostly occupied by mixed- to suspended-load rivers. As in many cases mostly coring-based evidence is available, the observation and measurement is limited to lithology and lithofacies boundaries; facies geometry must be inferred. Moreover, in those environments differences in lithofacies are obscured by a significantly reduced range of grain size distributions. An example of an ancient channel belt of Late Glacial to Holocene age serves to delineate the methodical practice and utility of the fluvial architecture approach. Field evidence is obtained from detailed cross-sectional surveys and comprises descriptions of lithofacies, structural, pedogenetical, biotic features, Munsell color, and total organic carbon magnetic volume susceptibility. Cross-sectional lithofacies information is represented by spatially attributed, scaled borehole logs. The example also accentuates the need for applying additional stratigraphical methods such as physical age determination, macrofossil analysis, and tephrological stratigraphy. These methods form the basis to discern stacked channel facies and derive a diachrony of channel forms. Thus, the adapted architecture approach provides a significant surplus of information on channel dimensions, ages, and channel-floodplain interconnectedness. Distinct fluvial landforms such as channels, levees, abandoned channels, swamps, and floodplain flats can be highlighted. A number of methodical constraints are discussed in detail, e.g., the sharpness of channel element geometry and the underlying ordering of bounding surfaces. Moreover, it is shown that the analytical process resembles an iterative looping process that is led by deduction. Many geomorphologists and multi-disciplinary floodplain researchers collect sedimentary data but still neglect utilizing the potential of architectural analysis. The study makes clear that sedimentological approaches used in 'big river' floodplains also apply to small valleys; in fact, the procedures for facies reconstruction need to be adjusted to each individual case study. Alluvial architecture analysis provides the tools to reveal interconnectedness (or disconnectedness) of channel, near-channel, and overbank fluvial landforms, which is essential for a geomorphological understanding of floodplain evolution.

  18. Analysis of Fluvial Bed Sediments Along the Apalachicola River, Florida through Field Reconnaissance Studies

    NASA Astrophysics Data System (ADS)

    Passeri, D.; Hagen, S. C.; Daranpob, A.; Smar, D. E.

    2011-12-01

    River competence is an important parameter in understanding sediment transport in fluvial systems. Competence is defined as the measure of a stream's ability to transport a certain maximum grain size of sediment. Studies have shown that bed sediment particle size in rivers and streams tends to vary spatially along the direction of stream flow. Over a river section several reaches long, variability of sediment particle sizes can be seen, often becoming finer downstream. This phenomenon is attributed to mechanisms such as local control of stream gradient, coarse tributary sediment supply or particle breakdown. Average particle size may also be smaller in tributary sections of rivers due to river morphology. The relationship between river mean velocity and particle size that can be transported has also been explored. The Hjulstrom curve classifies this relationship by relating particle size to velocity, dividing the regions of sedimentation, transportation, and erosion. The curve can also be used to find values such as the critical erosion velocity (the velocity required to transport particles of various sizes in suspension) and settling velocity (the velocity at which particles of a given size become too heavy to be transported and fall out of suspension, consequently causing deposition). The purpose of this research is to explore the principles of river competence through field reconnaissance collection and laboratory analysis of fluvial sediment core samples along the Apalachicola River, FL and its distributaries. Sediment core samples were collected in the wetlands and estuarine regions of the Apalachicola River. Sieve and hydrometer analyses were performed to determine the spatial distribution of particle sizes along the river. An existing high resolution hydrodynamic model of the study domain was used to simulate tides and generate river velocities. The Hjulstrom curve and the generated river velocities were used to define whether sediment was being transported, eroded or deposited at the different locations in the river and its distributaries. Parameters such as critical erosion velocity and settling velocity were also calculated to describe sediment transport along the channel. This research provides a better understanding of the fluvial geomorphic system, particularly sediment transport in channels. It also provides excellent validation data for future sediment transport studies in similar fluvial study domains.

  19. Stream capture and piracy recorded by provenance in fluvial fan strata

    NASA Astrophysics Data System (ADS)

    Mikesell, Leslie R.; Weissmann, Gary S.; Karachewski, John A.

    2010-03-01

    Stream capture and piracy in tectonically active regions have been described in geomorphic systems worldwide; however, few studies show the influence stream capture has on the rock record. We present an analysis of fluvial fan stratigraphy that developed as a result of multiple stream capture events, building a complex stratigraphic succession beneath the Lawrence Livermore National Laboratory (LLNL), California. The LLNL site is located in the southeast portion of the tectonically active Livermore Basin, a transpressional basin in the California Coast Ranges. Geomorphic evidence for this stream capture include: (1) the Arroyo Seco enters the basin from the south through an uplifted fault block, (2) south of this fault block lies an abandoned Arroyo Seco fluvial fan, (3) north of the fault block, in the Livermore Basin, Arroyo Seco built a 7-km 2 fluvial fan, apparently forcing the Arroyo Las Positas, a smaller stream that enters the basin from the east, northward around the Arroyo Seco fan, and (4) a knickpoint exists near the point of capture on Arroyo Seco. Stratigraphic evidence reflecting this shift in the Arroyo Seco position into the Livermore Basin was evaluated through a provenance study of 215 gravel units from 34 boreholes spaced evenly over the 2.6 km 2 LLNL site. The Arroyo Seco derives its sediment from both the Jurassic-Cretaceous Franciscan Assemblage and the Altamont Hills (which are comprised of Mesozoic Great Valley Group and Tertiary continental sediments). The Arroyo Las Positas drains only the Altamont Hills and thus lacks the Franciscan Assemblage-derived clasts. The origin of the individual gravel units was determined by the percentage of Franciscan Assemblage indicator pebbles (red chert, green chert and blueschist) in the samples. Through this analysis, we determined that high-percentage Franciscan Assemblage-derived clasts were present below a depth of approximately 35 m below the surface, low-percentage Franciscan Assemblage-derived clasts were present at depths between 35 m and 18 m, and high-percentage Franciscan Assemblage-derived clasts were present from depths of approximately 18 m to the surface of the fluvial fan. These results indicate that the Arroyo Seco flowed north and deposited sediments at the LLNL site, then was later absent from the basin at which time it formed a fan south of the fault block. During this absence of the Arroyo Seco, the Arroyo Las Positas, a westerly flowing stream, dominated the sediment supply at the LLNL site. The Arroyo Seco was then captured by a gully headward eroding through the uplifted fault block, redirecting the Arroyo Seco into the basin once again. This history of multiple stream captures created three stratigraphic units with alternating overall channel and paleoflow orientations.

  20. Fluvial armor

    Microsoft Academic Search

    G. Parker; A. J. Sutherland

    1990-01-01

    Mobile armor layers which form during bed load transport of non-uniform sediments are shown to be closely related to the static armor layers that form by selective erosion as a result of the action of clear water flows. Two previously published numerical models of the transport of non-uniform sediments are used as a basis for the discussion. Each model is

  1. Magmatic Intrusions and a Hydrothermal Origin for Fluvial Valleys on Mars

    NASA Technical Reports Server (NTRS)

    Gulick, Virginia C

    1998-01-01

    Numerical models of Martian hydrothermal systems demonstrate that systems associated with magmatic intrusions greater than several hundred cubic kilometers can provide sufficient groundwater outflow to form the observed fluvial valleys, if subsurface permeability exceeds about 1.0 darcy. Groundwater outflow increases with increasing intrusion volume and subsurface permeability and is relatively insensitive to intrusion depth and subsurface porosity within the range considered here. Hydrothermally-derived fluids can melt through 1 to 2 km thick ice-rich permafrost layers in several thousand years. Hydrothermal systems thus provide a viable alternative to rainfall for providing surface water for valley formation. This mechanism can form fluvial valleys not only during the postulated early warm, wet climatic epoch, but also during more recent epochs when atmospheric conditions did not favor atmospheric cycling of water. The clustered distribution of the valley networks on a given geologic surface or terrain unit of Mars may also be more compatible with localized, hydrothermally-driven groundwater outflow than regional rainfall. Hydrothermal centers on Mars may have provided appropriate environments for the initiation of life or final oases for the long-term persistence of life.

  2. Preparing for uncertainty: toward managing fluvial geomorphic assessment of Massachusetts rivers

    NASA Astrophysics Data System (ADS)

    Hatch, C. E.; Mabee, S. B.; Slovin, N. B.; Vogel, E.

    2014-12-01

    Climate scientists predict (and have already observed) that in the Northeastern U.S., individual storms may be more intense, and that there will be more precipitation on an annual basis. In steep post-glacial terrain, erosion caused by floodwaters is the largest destructive force during high-intensity storm events, and the force most likely to drive major morphological changes to riverbanks and channels. What remains uncertain is which watersheds or river reaches may be subjected to increased damage from more intense storms. This presents a challenge for scientific outreach and management. Many New England states have developed systems for delineating the potentially geomorphically active zones adjacent to rivers, and Vermont has an excellent assessment and land use management system informed by process-based fluvial geomorphologic science. To date, however, Massachusetts has neither. In this project we survey existing protocols for accurately predicting locations of fluvial erosion hazard, including using LiDAR and DEM models to extract basic morphologic metrics. Particularly in states or landscapes with high river density, and during a time of tight fiscal constraints, managers need automated methods that require a minimum of expert input. We test these methods in the Deerfield river watershed in Massachusetts and Vermont, and integrate our knowledge with that of the basin's agricultural and floodplain stakeholders. The results will inform development of a comprehensive river assessment and land use management system for the state of Massachusetts.

  3. Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana

    SciTech Connect

    Wilson, K.M. (Bryn Mawr College, PA (United States)); Dodson, P. (Univ. of Pennsylvania, Philadelphia (United States)); Fiorillo, A.R. (Carnegie Museum, Pittsburgh, PA (United States))

    1991-03-01

    Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana, has been the subject of intensive paleontological study for many years. However, little has been published on the sedimentology of the formation in this area. The authors have completed a preliminary field study of fluvial facies, with a view towards correcting this omission. Initial results include detailed facies descriptions and maps for five quarries along a line of transect stretching some 40 km parallel to depositional dip. Facies identified are predominantly overbank splays and levees, with common point bar/alluvial channel units and occasional small, possibly estuarine sand bodies in parts of the section. Shell beds (mainly oysters) and bedded, 1 m thick coals are also significant in some sections. Preliminary attempts at paleohydrology suggest river channels in some parts of the section were about 100 m wide and 2 m deep; however, other parts of the section exhibit much larger channel widths. Channel stacking is common. Preliminary results suggest a strong correlation between the occurrence of reddish brown carbonaceous silty shales, and dinosaur bone deposits.

  4. Depositional controls on tidally influenced fluvial successions, Neslen Formation, Utah, USA

    NASA Astrophysics Data System (ADS)

    Shiers, M. N.; Mountney, N. P.; Hodgson, D. M.; Cobain, S. L.

    2014-08-01

    The stratigraphic architecture of marginal marine successions records the interplay of autogenic and allogenic processes, and discerning their relative role in governing the morphology of the palaeoenvironment and the architecture of the preserved sedimentary succession is not straightforward. The Campanian Neslen Formation, Mesaverde Group, Utah, is a tidally influenced fluvial succession sourced from the Sevier Orogen, which prograded eastwards into the Western Interior Seaway. Detailed mapping in three dimensions of architectural relationships between sandstone bodies has enabled documentation of lateral and vertical changes in the style of channel-body stacking and analysis of the distribution of sedimentary evidence for tidal influence. Upwards, through the succession, sandstone channel bodies become larger and more amalgamated. Laterally, the dominant style of channel bodies changes such that ribbon channel-fills are restricted to the east of the study area whereas lateral accretion deposits dominate to the west. Combined allogenic and autogenic controls gave rise to the observed stratigraphy. A temporal decrease in the rate of accommodation generation resulted in an upward increase in amalgamation of sand-bodies. Autogenic processes likely played a significant role in moderating the preserved succession: up-succession changes in the style of stacking of channelized bodies could have arisen either from progradation of a distributive fluvial system or from an upstream nodal avulsion of a major trunk channel; accumulation of tide influenced, wave dominated units likely record episodes of delta-lobe abandonment, subsidence and submergence to allow accumulation of near shore sand bars with associated washover complexes.

  5. Fluvial and Lacustrine Processes in Meridiani Planum and the Origin of the Hematite by Aqueous Alteration

    NASA Technical Reports Server (NTRS)

    Newsom, H. E.; Barber, C. A.; Schelble, R. T.; Hare, T. M.; Feldman, W. C.; Sutherland, V.; Livingston, A.; Lewis, K.

    2003-01-01

    The prime MER landing site in Meridiani Planum is located on layered materials, including hematite, whose origin as lacustrine or aeolian sediments, or volcanic materials is uncertain. Our detailed mapping of the region provides important constraints on the history of the region. Our mapping of the location of fluvial and lacustrine land forms in the region relative to the layered deposits provides new evidence of a long history of erosion and deposition as has long been noted . In addition, our detailed mapping of the southern boundary of the hematite deposit strongly supports an association between longlived fluvial channels and lacustrine basins and the strongest hematite signatures. This evidence supports an origin of the hematite deposits by interaction with water under ambient conditions in contrast to suggestions of hydrothermal processes due to volcanic or impact crater processes. An important part of the story is the evidence for the localization of the layered deposits due to topographic control induce by the presence of a large early basin we have identified that extends to the north-east of the landing site. Distribution of current channel networks, drainages,

  6. Precambrian fluvial deposits: Enigmatic palaeohydrological data from the c. 2 1.9 Ga Waterberg Group, South Africa

    NASA Astrophysics Data System (ADS)

    Eriksson, Patrick G.; Bumby, Adam J.; Brümer, Jacobus J.; van der Neut, Markus

    2006-08-01

    Precambrian fluvial systems, lacking the influence of rooted vegetation, probably were characterised by flashy surface runoff, low bank stability, broad channels with abundant bedload, and faster rates of channel migration; consequently, a braided fluvial style is generally accepted. Pre-vegetational braided river systems, active under highly variable palaeoclimatic conditions, may have been more widespread than are modern, ephemeral dry-land braided systems. Aeolian deflation of fine fluvial detritus does not appear to have been prevalent. With the onset of large cratons by the Neoarchaean-Palaeoproterozoic, very large, perennial braided river systems became typical. The c. 2.06-1.88 Ga Waterberg Group, preserved within a Main and a smaller Middelburg basin on the Kaapvaal craton, was deposited largely by alluvial/braided-fluvial and subordinate palaeo-desert environments, within fault-bounded, possibly pull-apart type depositories. Palaeohydrological data obtained from earlier work in the Middelburg basin (Wilgerivier Formation) are compared to such data derived from the correlated Blouberg Formation, situated along the NE margin of the Main basin. Within the preserved Blouberg depository, palaeohydrological parameters estimated from clast size and cross-bed set thickness data, exhibit rational changes in their values, either in a down-palaeocurrent direction, or from inferred basin margin to palaeo-basin centre. In both the Wilgerivier and Blouberg Formations, calculated palaeoslope values (derived from two separate formulae) plot within the gap separating typical alluvial fan gradients from those which characterise rivers (cf. [Blair, T.C., McPherson, J.G., 1994. Alluvial fans and their natural distinction from rivers based on morphology, hydraulic processes, sedimentary processes, and facies assemblages. J. Sediment. Res. A64, 450-489.]). Although it may be argued that such data support possibly unique fluvial styles within the Precambrian, perhaps related to a combination of major global-scale tectono-thermal and atmospheric-palaeoclimatic events, a simpler explanation of these apparently enigmatic palaeoslope values may be pertinent. Of the two possible palaeohydrological formulae for calculating palaeoslope, one provides results close to typical fluvial gradients; the other formula relies on preserved channel-width data. We suggest that the latter will not be reliable due to problematic preservation of original channel-widths within an active braided fluvial system. We thus find no unequivocal support for a unique fluvial style for the Precambrian, beyond that generally accepted for that period and discussed briefly in the first paragraph.

  7. Depositional architecture of lacustrine-delta and fluvial systems of the Permian Epsilon and Toolachee Formations at Dullingari field, southeastern Cooper basin, south Australia

    Microsoft Academic Search

    W. A. Ambrose; D. S. Hamilton; M. H. Holtz

    1996-01-01

    The Epsilon and Toolachee Formations record a transition from lacustrine deltas to fluvial depositional systems in the southeastern part of the Cooper Basin. Gas reservoirs in these formations occur mainly in narrow (typically less than 2 mi [3.2 km] wide) belts of distributary- and fluvial-channel sandstones in structurally high areas in Dullingari field and neighboring areas. In a study by

  8. Lower Triassic sequence stratigraphy of the western part of the Germanic Basin (west of Black Forest): Fluvial system evolution through time and space

    Microsoft Academic Search

    Sylvie Bourquin; Samuel Peron; Marc Durand

    2006-01-01

    The aim of this paper is to analyse the fluvial evolution of the Lower Triassic in the western part of the Germanic Basin through time and space, as well as the impact of the geodynamic and climatic setting on the preservation of fluvial deposits. The Lower Triassic crops out only in the Vosges Massif and the Black Forest, so well-log

  9. U-Pb single zircon grain dating of Present fluvial and Cenozoic aeolian sediments from Gabon: consequences on sediment provenance, reworking, and

    E-print Network

    Demouchy, Sylvie

    U-Pb single zircon grain dating of Present fluvial and Cenozoic aeolian sediments from Gabon detrital zircon from terrigenous sediments are used to determine the sources. Pre- sent fluvial sand-bars of the Ogooué river yield age spectra of detrital zircons in agreement with Archean and Early Pro- terozoic

  10. Vegetation change in dryland environments: understanding changes in fluvial fluxes via changes in hydrological connectivity

    NASA Astrophysics Data System (ADS)

    Puttock, A.; Brazier, R. E.; Dungait, J. A. J.; Bol, R.; Macleod, C. J. A.

    2012-04-01

    Dryland environments are estimated to cover around 40% of the global land surface (Okin et al, 2009) and are home to approximately 2.5 billion people (Reynolds et al. 2007). Many of these areas have recently experienced extensive land degradation. One such area and the focus of this project is the semi-arid US Southwest, where degradation over the past 150 years has been characterised by the invasion of woody vegetation into grasslands. The transition from grass to woody vegetation results in a change in ecosystem structure and function (Turnbull et al, 2008). Structural change is typically characterised by an increased heterogeneity of soil and vegetation resources, associated with reduced vegetation coverage. Functional change is characterised by an increased vulnerability to soil erosion and the potential loss of key nutrients to adjacent fluvial systems. Such loss of resources may impact heavily upon the amount of carbon that is sequestered by these environments and the amount of carbon that is lost as the land becomes more degraded. Therefore, understanding these vegetation transitions is significant for sustainable land use and global biogeochemical cycling. Connectivity is a key concept in understanding the hydrological response to this vegetation change, with reduced vegetation coverage in woody environments being associated with longer and more connected overland flow pathways. This increase in hydrological connectivity results in an accentuated rainfall-runoff response and increased fluvial fluxes of eroded sediment and associated soil organic carbon and other nutrients. This project uses an ecohydrological approach, characterising ecological structure and monitoring natural rainfall-runoff events over bounded plots with different vegetation covering the transitions from C4 pure-grass (Bouteloua eriopoda) to C3 creosote (Larrea tridentate) shrubland and C3 piñon-juniper (Pinus edulis-Juniperus monosperma) mixed stand woodland. Data collected quantifies fluvial fluxes of sediment and associated soil organic matter and carbon that is lost from across the grass-to-shrub and grass-to-woodland transition (where change in space is taken to indicate a similar change through time). Structural characterisation data along with results collected during the 2010 and 2011 monsoon seasons will be presented; illustrating the usefulness of viewing environmental structure via the concept of connectivity when trying to understand fluxes of water, sediment and associated nutrients.

  11. Developing an Understanding of Vegetation Change and Fluvial Carbon Fluxes in Semi-Arid Environments

    NASA Astrophysics Data System (ADS)

    Puttock, A.; Brazier, R. E.; Dungait, J. A. J.; Bol, R.; Macleod, C. J. A.

    2012-04-01

    Dryland environments are estimated to cover around 40% of the global land surface (Okin et al, 2009) and are home to approximately 2.5 billion people (Reynolds et al. 2007). Many of these areas have recently experienced extensive land degradation. One such area and the focus of this project is the semi-arid US Southwest, where degradation over the past 150 years has been characterised by the invasion of woody vegetation into grasslands. Transition from grass to woody vegetation results in a change in ecosystem structure and function (Turnbull et al, 2008). Structural change is typically characterised by an increased heterogeneity of soil and vegetation resources, associated with reduced vegetation coverage and an increased vulnerability to soil erosion and the potential loss of key nutrients to adjacent fluvial systems. Such loss of resources may impact heavily upon the amount of carbon that is sequestered by these environments and the amount of carbon that is lost as the land becomes more degraded. Therefore, understanding these vegetation transitions is significant for sustainable land use and global biogeochemical cycling. This project uses an ecohydrological approach, monitoring natural rainfall-runoff events over six bounded plots with different vegetation coverage. The experiment takes advantage of a natural abundance stable 13C isotope shift from C3 piñon-juniper (Pinus edulis-Juniperus monosperma) mixed stand through a C4 pure-grass (Bouteloua eriopoda) to C3 shrub (Larrea tridentata). Data collected quantify fluvial fluxes of sediment and associated soil organic matter and carbon that is lost from across the grass-to-shrub and grass-to-woodland transition (where change in space is taken to indicate a similar change through time). Results collected during the 2010 and 2011 monsoon seasons will be presented, illustrating that soil and carbon losses are greater as the ecosystem becomes more dominated by woody plants. Additionally this project utilises novel biogeochemical techniques, using stable 13C isotope and lipid biomarker analyses, to trace and partition fluvial soil organic matter and carbon fluxes during these events. Results show that biomarkers specific to individual plant species can be used to define the provenance of carbon, quantifying whether more piñon or juniper derived carbon is mobilised from the upland plots, or whether more Larrea tridentata carbon is lost when compared to Bouteloa eripoda losses in the lowlands. The combined approach of monitoring carbon fluxes and tracing types of carbon shows great promise for improved understanding of carbon dynamics in areas subject to rapid vegetation change.

  12. Late Quaternary fluvial incision rates in a marine terraced landscape, southeastern Crete, Greece

    NASA Astrophysics Data System (ADS)

    Karymbalis, Efthimios; Papanastassiou, Dimitris; Valkanou, Kanella; Gaki-Papanastassiou, Kalliopi

    2014-05-01

    Along the southern coast of the island of Crete, a series of five east-west oriented Late Pleistocene marine terraces exist, demonstrating the significant coastal uplift of this area. These terraces, ranging in elevation from 10 to 160m, are deformed by the vertical movements of the NNE-SSW trending and dipping west normal fault of Ierapetra. This study focuses on defining rates of fluvial incision for the last 410 Ka along valley systems that drain the tectonically uplifting area of Ierapetra, south Crete. The studied streams have a N-S flow direction and discharge into the Libyan Sea. Some of them are developed on the uplifted block of the Ierapetra normal fault whereas others drain the subsiding area west of the fault. The lower reaches of the study streams cut down through these marine terraces, which have been recognized, mapped in detail and correlated with Late Pleistocene Oxygen-Isotope Stages of high sea-level stands following the global sea-level fluctuations. These terraces of known age were used as reference surfaces in order to determine fluvial incision rates as the lower reaches of the streams cut down through these platforms. To evaluate incision rates, thirty five topographic valley cross-sections were drawn through fieldwork measurements as well as using a digital elevation model (DEM) produced by detailed topographic diagrams at the scale of 1:5,000. Cross valley profiles were constructed at specific locations where streams cut down the inner edges of the marine terraces because these points correspond precisely to the age of the palaeo-shoreline during the interglacial stage. For each cross-section the ratio of valley floor width to valley height (Vf) and long-term mean stream incision rates were estimated for the last 410 Ka. The geomorphic evolution of the valleys has been mainly affected by the lithology of the bedrock, sea level fluctuations during the late Quaternary, the head-ward erosion and incision of the channels, as well as both the regional uplift and the uplift due to the activity of the Ierapetra fault. Fluvial incision rates are higher for the streams developed at the footwall depending strongly on the distance from the trace of the fault. Downcutting rates are comparable with the slip rate of the Ierapetra fault over the last 410 Ka.

  13. Palynostratigraphy and sedimentary facies of Middle Miocene fluvial deposits of the Amazonas Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Dino, Rodolfo; Soares, Emílio Alberto Amaral; Antonioli, Luzia; Riccomini, Claudio; Nogueira, Afonso César Rodrigues

    2012-03-01

    Palynostratigraphic and sedimentary facies analyses were made on sedimentary deposits from the left bank of the Solimões River, southwest of Manaus, State of Amazonas, Brazil. These provided the age-dating and subdivision of a post-Cretaceous stratigraphic succession in the Amazonas Basin. The Novo Remanso Formation is subdivided into upper and lower units, and delineated by discontinuous surfaces at its top and bottom. The formation consists primarily of sandstones and minor mudstones and conglomerates, reflecting fluvial channel, point bar and floodplain facies of a fluvial meandering paleosystem. Fairly well-preserved palynoflora was recovered from four palynologically productive samples collected in a local irregular concentration of gray clay deposits, rich in organic material and fossilized wood, at the top of the Novo Remanso Formation upper unit. The palynoflora is dominated by terrestrial spores and pollen grains, and is characterized by abundant angiosperm pollen grains ( Tricolpites, Grimsdalea, Perisyncolporites, Tricolporites and Malvacearumpollis). Trilete spores are almost as abundant as the angiosperm pollen, and are represented mainly by the genera Deltoidospora, Verrutriletes, and Hamulatisporis. Gymnosperm pollen is scarce. The presence of the index species Grimsdalea magnaclavata Germeraad et al. (1968) indicates that these deposits belong to the Middle Miocene homonymous palynozone (Lorente, 1986; Hoorn, 1993; Jaramillo et al., 2011). Sedimentological characteristics (poorly sorted, angular to sub-angular, fine to very-coarse quartz sands facies) are typical of the Novo Remanso Formation upper part. These are associated with a paleoflow to the NE-E and SE-E, and with an entirely lowland-derived palinofloristic content with no Andean ferns and gymnosperms representatives. All together, this suggests a cratonic origin for this Middle Miocene fluvial paleosystem, which was probably born in the Purus Arch eastern flank and areas surrounding the crystalline. The palynological analysis results presented herein are the first direct and unequivocal evidence of the occurrence of Middle Miocene deposits in the central part of the Amazonas Basin. They also provide new perspectives for intra- and interbasin correlations, as well as paleogeographic and paleoenvironmental interpretations for the later deposition stages in the northern Brazilian sedimentary basins.

  14. Fluvial Tufa Evidence of Late Pleistocene Wet Intervals from Santa Barbara, Southern California

    NASA Astrophysics Data System (ADS)

    Ibarra, Y.; Corsetti, F. A.; Feakins, S. J.; Rhodes, E. J.; Kirby, M. E.

    2014-12-01

    Past pluvials in the western United States provide valuable context for understanding regional hydroclimate variability. Here we report evidence of conditions substantially wetter than today from fluvial tufa deposits located near Zaca Lake, Santa Barbara County, California that have been dated by radiocarbon (14C) and Infra-Red Stimulated Luminescence (IRSL). Two successions of tufa deposition occur within a small catchment that drains Miocene Monterey Formation bedrock: 1) a fluvial deposit (0?0.5 m thick, 200 m in extent) that formed along a narrow valley below a modern spring, and 2) a perched deposit about 10 m higher (2 m thick, 15 m in extent). IRSL and radiocarbon dating of the perched carbonates suggests at least two episodes of carbonate growth: one at 19.4 ± 2.4 (1?) through 17.8 ± 2.8 (1?) ka and another at 11.9 ± 1.5 (1?) ka verified with a charcoal 14C age of 10.95 ± 0.12 (2?) cal ka BP. The relationship between the perched and fluvial spring deposits is inferred to represent a drop in the water table of more than 10 m associated with a transition from a wet climate in the late glacial to a dry Holocene today. The wet period indicated by tufa growth between 19.4 and 17.8 ka is relatively consistent with other California climate records both north and south of Zaca Lake. However, tufa growth ca. 12 to 11 ka demonstrates wet conditions occurred as far south as Zaca Lake during the Younger Dryas event, in contrast to climate records farther south in Lake Elsinore indicating persistently dry conditions through this interval. A small shift north in the average position of the winter season storm track could explain wet winters at Zaca while at the same time generating dry winters at Lake Elsinore, 275 km southwest of Zaca. If true, these data indicate that rather small latitudinal shifts in the average winter season storm track can produce large changes in regional hydroclimate.

  15. How the eastern Qilian Shan Mountain was deformed, revealed by deformed fluvial terraces

    NASA Astrophysics Data System (ADS)

    Hu, X.; Pan, B.; Gao, H.; Hu, Z.; Geng, H.; Cao, B.

    2012-12-01

    The northwest-southeastern treading Qilian Shan Mountain, margining the northeastern Tibetan Plateau, has been uplifting and deforming related to thrust faults bordering the mountain range in the north. By now, the fault thrust rate and how the mountain was uplifted and deformed is poorly documented along the eastern Qilian Shan. In this study, several flights of late Quaternary fluvial terraces along two rivers (Xiying River and Jinta River), sourced from the mountain crest and flowing transecting these thrust faults and folds, are surveyed by differential GPS with the accuracy of lower than 10 centimeters. Meanwhile, the abandonment times of terrace surfaces were dated by OSL dating on the overlying loess above the fluvial deposits. Analysis results of height data show that fluvial terrace surfaces were obviously deformed related to thrusting and folding. At first, we derive an average uplift rate of 0.05~0.2 mm/yr, which is contributed by folding along the low-mountain range since 120 ka B.P. When the uplift contributed by thrust is added, the total rate of uplift would be 0.45-0.60 mm/yr. The second, by the geometry of terrace surface height, the thrust geometry under the surface is deduced. Along the low-mountain range (with elevation from 2000 m to 3000 m), the dip angle of thrust is bended from ~30° to ~50° at the depth of around 15 km, and at the depth of ~20 km, the thrust dip angle is changed to ~26°. Along the Huangcheng-Taerzhuang Fault, which bordering the high-mountain range (with elevation from 3000 m to 5000 m) and the low-mountain range, the dip angle is bended from ~70° at the surface to ~47° below the depth of ~5 km, and at the depth below 23 km, the dip angel of the thrust is >30°. We conclude that in the late Quaternary, the deforming of mountain range along the eastern Qilian Shan is accomplished both by thrusting and folding; the different uplift rate is mainly caused by different thrust angle in the depth along the eastern Qilian Shan Mountain.

  16. Fluvial dynamics of an anabranching river system in Himalayan foreland basin, Baghmati river, north Bihar plains, India

    Microsoft Academic Search

    Vikrant Jain; R. Sinha

    2004-01-01

    Anabranching river systems are now regarded as a separate class in river classifications owing to their distinctive morphological\\/hydrological characteristics and fluvial processes. A better understanding of anabranching rivers still needs detailed data from different environmental and geographical settings. This paper presents a detailed account of an anabranching river system from the Himalayan foreland basin. The Baghmati river system from north

  17. Sedimentation in a discharge dominated fluvial-lacustrine system: the Neogene Productive Series of the South Caspian Basin, Azerbaijan

    Microsoft Academic Search

    D. J Hinds; E Aliyeva; M. B Allen; C. E Davies; S. B Kroonenberg; M. D Simmons; S. J Vincent

    2004-01-01

    The largely lower Pliocene Productive Series and its regional equivalents contain the major hydrocarbon reservoirs of the South Caspian Basin. Examination of outcrops in the Apsheron region, Azerbaijan, has resulted in re-interpretation of the depositional environments of the Productive Series. The lower part of the Productive Series consists of sandstones and mudstones interpreted as channelised and sheetflood fluvial deposits, intercalated

  18. Fluvial incision into bedrock: Insights from morphometric analysis and numerical modeling of gorges incising glacial hanging valleys

    E-print Network

    Boyer, Edmond

    surrounding the gorges in order to quantify the amount of fluvial incision and knickpoint retreat. From morphometric analyses, we find that mean channel gradients and widths, as well as knickpoint retreat rates to be no relation between horizontal retreat and vertical downwearing of knickpoints. Assuming a postglacial origin

  19. Individual and cumulative effects of agriculture, forestry and metal mining activities on the metal and phosphorus content of fluvial

    E-print Network

    Northern British Columbia, University of

    and phosphorus content of fluvial fine-grained sediment; Quesnel River Basin, British Columbia, Canada Tyler B University Way, Prince George, British Columbia V2N 4Z9, Canada Quesnel River Research Centre, University mining on the quality of fine-grained sediment (b63 m) was investigated in the Quesnel River Basin (QRB

  20. ANCIENT DELTAS IN A MARTIAN CRATE LAKE: FASSETT AND HEAD 1 Fluvial Sedimentary Deposits on Mars: Ancient Deltas

    E-print Network

    Head III, James William

    ANCIENT DELTAS IN A MARTIAN CRATE LAKE: FASSETT AND HEAD 1 Fluvial Sedimentary Deposits on Mars in the Nili Fossae region of Mars reveal two valley networks (~80 and ~200 km long) that each formed], but instead of sediments at the MER Spirit's initial landing site, the rover found a broad plain of apparently

  1. Movements of Fluvial Bonneville Cutthroat Trout in the Thomas Fork of the Bear River, Idaho–Wyoming

    Microsoft Academic Search

    Warren T. Colyer; Jeffrey L. Kershner; Robert H. Hilderbrand

    2005-01-01

    The majority of interior subspecies of cutthroat trout Oncorhynchus clarkii have been extirpated from large rivers by anthropogenic activities that have fragmented habitats and introduced nonnative competitors. Selective pressures against migratory behaviors and main-stem river occupation, coupled with conservation strategies that isolate genetically pure populations above barriers, have restricted gene flow and prevented expression of the fluvial life history in

  2. Identifying Complex Fluvial Sandstone Reservoirs Using Core, Well Log, and 3D Seismic Data: Cretaceous Cedar Mountain and Dakota Formations,

    E-print Network

    Seamons, Kent E.

    i Identifying Complex Fluvial Sandstone Reservoirs Using Core, Well Log, and 3D Seismic Data Log, and 3D Seismic Data: Cretaceous Cedar Mountain and Dakota Formations, Southern Uinta Basin, Utah core, well-log, and 3D seismic data. The detailed stratigraphy and sedimentology of the interval were

  3. Fluvial facies architecture in small-scale river systems in the Upper Dupi Tila Formation, northeast Bengal Basin, Bangladesh

    E-print Network

    Kulp, Mark

    Fluvial facies architecture in small-scale river systems in the Upper Dupi Tila Formation facies analysis of the Upper Dupi Tila Formation. Four facies have been identified: trough cross mud with rootlets (Fm). Facies analysis supplemented with embedded Markov chain analysis, reveals

  4. Trends in grain size and BET surface area in cold-arid versus warm-semiarid fluvial systems

    NASA Astrophysics Data System (ADS)

    Marra, Kristen R.; Soreghan, Gerilyn S.; Elwood Madden, Megan E.; Keiser, Leslie J.; Hall, Brenda L.

    2014-02-01

    Sediment grain size and surface area impose critical controls on the rates of chemical weathering, even in cold-based (i.e., polar) glacial systems, where extensive chemical weathering traditionally has been considered minimal owing to low temperatures. Production of fine-grained material increases the surface area of sediments, priming mineral surfaces for chemical weathering. Comparison among grain size and reactive surface area of sediments along granitoid-sourced fluvial transects between a cold-arid, glacial (Wright Valley, Antarctica) and a warm-semiarid, nonglacial (Wichita Mountains, Oklahoma) environment indicates opposing trends downstream within the silt and clay (< 63 ?m) fraction. In the polar glacial transect, the silt and clay fraction coarsens and exhibits a corresponding decrease in mineral surface area with fluvial transport. This is inferred to reflect rapid dissolution of fine-grained eolian material trapped on a glacier surface and released during summer melting. Fluvial sediments from the warm, nonglacial system exhibit the opposite trend, wherein a downstream decrease in grain size and increase in surface area suggest incongruent chemical weathering resulting in clay-sized secondary weathering phases. The observed trends highlight the important roles of reactive surface area and solute chemistry, which are closely linked to climate, in determining chemical weathering rates. Such trends are potentially discernible in the sediment record, providing a means to refine climatic inferences from proximal fluvial strata and further constrain the influence of chemical weathering on modern and on ancient global carbon cycles.

  5. The effect of salt crust on the thermal conductivity of one sample of fluvial particulate materials under Martian atmospheric pressures

    Microsoft Academic Search

    Marsha A. Presley; Robert A. Craddock; Natalya Zolotova

    2009-01-01

    A line-heat source apparatus was used to measure thermal conductivities of a lightly cemented fluvial sediment (salinity = 1.1 g · kg?1), and the same sample with the cement bonds almost completely disrupted, under low pressure, carbon dioxide atmospheres. The thermal conductivities of the cemented sample were approximately 3× higher, over the range of atmospheric pressures tested, than the thermal

  6. A comparison of factors controlling sedimentation rates and wetland loss in fluvial-deltaic systems, Texas Gulf coast

    USGS Publications Warehouse

    White, W.A.; Morton, R.A.; Holmes, C.W.

    2002-01-01

    Submergence of coastal marshes in areas where rates of relative sea-level rise exceed rates of marsh sedimentation, or vertical accretion, is a global problem that requires detailed examination of the principal processes that establish, maintain, and degrade these biologically productive environments. Using a simple 210Pb-dating model, we measured sedimentation rates in cores from the Trinity, Lavaca-Navidad, and Nueces bayhead fluvial-deltaic systems in Texas where more than 2000 ha of wetlands have been lost since the 1950s. Long-term average rates of fluvial-deltaic aggradation decrease southwestward from 0.514 ?? 0.008 cm year -1 in the Trinity, 0.328 ?? 0.022 cm year -1 in the Lavaca-Navidad, to 0.262 ?? 0.034 cm year -1 in the Nucces. The relative magnitudes of sedimentation and wetland loss correlate with several parameters that define the differing fluvial-deltaic settings, including size of coastal drainage basin, average annual rainfall, suspended sediment load, thickness of Holocene mud in the valley fill, and rates of relative sea-level rise. There is some evidence that upstream reservoirs have reduced wetland sedimentation rates, which are now about one-half the local rates of relative sea-level rise. The extant conditions indicate that fluvial-deltaic marshes in these valleys will continue to be lost as a result of submergence and erosion. ?? 2002 Elsevier Science B.V. All rights reserved.

  7. Inverted fluvial features in the Aeolis\\/Zephyria Plana region, Mars: Formation mechanism and initial paleodischarge estimates

    Microsoft Academic Search

    Devon M. Burr; Rebecca M. E. Williams; Kimberly D. Wendell; Matthew Chojnacki; Joshua P. Emery

    2010-01-01

    A subset of the sinuous ridges (SRs) in the Aeolis\\/Zephyria Plana (AZP) region of Mars has been previously hypothesized to be inverted fluvial features, although the precise induration and erosion mechanisms were not specified. Morphological observations and thermal inertia data presented here support this hypothesis. A variety of mechanisms can cause inversion, and identification of the specific events that lead

  8. PUBLISHED ONLINE: 4 AUGUST 2013 | DOI: 10.1038/NGEO1891 Erosion of biofilm-bound fluvial sediments

    E-print Network

    Luo, Xiaoyu

    LETTERS PUBLISHED ONLINE: 4 AUGUST 2013 | DOI: 10.1038/NGEO1891 Erosion of biofilm-bound fluvial biofilms, which com- prise diverse consortia of species housed in sticky extracellular polysaccharides not hold for biofilm-bound sediments. Instead, biostabilized sediment behaves more like an elastic membrane

  9. Monitoring Fluvial Erosion of Cohesive Materials Using the Photo-Electronic Erosion Pin Sensor in Clear Creek, IA

    NASA Astrophysics Data System (ADS)

    Bertrand, F.; Papanicolaou, T.

    2009-12-01

    Fluvial erosion incites significant bridge scour and large-scale bank erosion causing estimated $1.1 billion damage in the Midwest. Conventional, manual, field monitoring methods, typically erosion pins, cross-section resurveys or terrestrial photogrammetry, used to monitor fluvial erosion rates merely provide a net change in bank surface retreat since the previous measurement. If mass wasting has occurred, the ongoing fluvial erosion would be masked. Erosion event timing, and the precise bank response to individual flow or flow hydrograph changes, is generally uncertain. Thus, a technique that automatically quantifies bank erosion on a continuous basis is needed. This study will monitor the bank response to individual flow (i.e., fluvial erosion) using the Photo-Electronic Erosion Pin (PEEP) sensors in Clear Creek Iowa. It attends to monitor a full episode of bank change, including event timings and magnitude information for specific erosion and deposition events, which can be compared to flow discharges and hydrographs. If exploited, this method can lead to more detailed analysis of bank erosion related to temporal fluctuations in the suspected hydraulic forces.

  10. Stratigraphy of the fluvial deposits of the Salado river basin, Buenos Aires Province: Lithology, chronology and paleoclimate

    NASA Astrophysics Data System (ADS)

    Fucks, E.; Pisano, M. F.; Huarte, R. A.; Di Lello, C. V.; Mari, F.; Carbonari, J. E.

    2015-07-01

    The regional landscape of the Salado depression is related to weathering, eolian and fluvial processes generated under different climatic conditions. Although during most of the Holocene the climatic conditions were warm and humid, previously, a vast plain dominated by deflation processes and enhanced by weathering processes was developed in an arid environment. Fluvial deposits produced afterwards are continuous and lithologically homogeneous, which allows differentiation and characterization of the entire stratigraphic sequence. The stratigraphic units of this area, closely related to the paleoclimatic conditions, are recognized and characterized. Three lithostratigraphic units of fluvial origin (Members) and two paleosols have been differentiated. The first ones were grouped in the Luján Formation. Some of the units are related to other ones previously recognized in this area (La Chumbiada Member and La Pelada Geosol), but others have no similarity or relationship with previously known units (Gorch and Puente Las Gaviotas Members, and Frigorífico Belgrano Geosol). Radiocarbon ages suggest that the fluvial sequences were deposited after the glacial maximum, corresponding to MIS 1, except for the basal levels of the lower member which is late Late Pleistocene. Although the general paleoclimatic conditions were related to warm and humid climate, events related to water deficits were also recognized, which could be related to the Younger Dryas, the middle Holocene and the late Holocene.

  11. When do plants modify fluvial processes? Plant-hydraulic interactions under variable flow and sediment supply rates

    NASA Astrophysics Data System (ADS)

    Manners, Rebecca B.; Wilcox, Andrew C.; Kui, Li; Lightbody, Anne F.; Stella, John C.; Sklar, Leonard S.

    2015-02-01

    Flow and sediment regimes shape alluvial river channels; yet the influence of these abiotic drivers can be strongly mediated by biotic factors such as the size and density of riparian vegetation. We present results from an experiment designed to identify when plants control fluvial processes and to investigate the sensitivity of fluvial processes to changes in plant characteristics versus changes in flow rate or sediment supply. Live seedlings of two species with distinct morphologies, tamarisk (Tamarix spp.) and cottonwood (Populus fremontii), were placed in different configurations in a mobile sand-bed flume. We measured the hydraulic and sediment flux responses of the channel at different flow rates and sediment supply conditions representing equilibrium (sediment supply = transport rate) and deficit (sediment supply < transport rate). We found that the hydraulic and sediment flux responses during sediment equilibrium represented a balance between abiotic and biotic factors and was sensitive to increasing flow rates and plant species and configuration. Species-specific traits controlled the hydraulic response: compared to cottonwood, which has a more tree-like morphology, the shrubby morphology of tamarisk resulted in less pronation and greater reductions in near-bed velocities, Reynolds stress, and sediment flux rates. Under sediment-deficit conditions, on the other hand, abiotic factors dampened the effect of variations in plant characteristics on the hydraulic response. We identified scenarios for which the highest stem-density patch, independent of abiotic factors, dominated the fluvial response. These results provide insight into how and when plants influence fluvial processes in natural systems.

  12. Lower Vistula fluvial lakes as possible places of deep groundwaters effluence (Grudzi?dz Basin, North Central Poland)

    NASA Astrophysics Data System (ADS)

    Kordowski, Jaroslaw; Kubiak-Wójcicka, Katarzyna; Solarczyk, Adam; Tyszkowski, Sebastian

    2014-05-01

    Regarding the outflow the Vistula River is the largest river in the Baltic catchment. In its lower course, below Bydgoszcz, in the Late Holocene Vistula channel adopted an weakly anastomosing fluvial pattern destroyed by intensive human hydrotechnical activity and by the regulation which have intensified about 200 years ago. Channel regulation have left many artificially separated fluvial lakes. Part of them infilled rapidly but the majority have persisted to present day almost unchanged. It has also arised the question: what drives the resistence for silting? To solve the problem there were conducted simultaneous hydrological and geomorphological investigations, because there were two concepts: one that the mineral material is removed from fluvial lakes while high stands by flood waters and second that the material is removed due to high groundwater "exchange" rate when the fluvial lake has a sufficient hydrological connectivity to the main Vistula channel. The Vistula valley crosses morainic plains of the last glaciation. On the average it has about 10 km width and is incised about 70 - 80 m deep, compared to neighbouring plains, dissecting all the Quaternary aquifers. On the floodplain area the Quaternary sediments lay with a layer of only 10-20 m thickness over Miocene and Oligocene sands. In favourable conditions, particularly while a low stand there exists the possibility of Tertiary water migration toward the surface of fluvial lakes provided they have not continuous flood sediments cover on their floors. As an example of such a lake with an intensive water exchange rate by supposed deep groundwaters was chosen the Old Vistula lake (Stara Wis?a) near Grudzi?dz town. The lake has an area of 40 ha, mean depth 1,73 m, maximum depth 8 m, length about 4 km and medium width about 100 m. In the years 2011-2014, with two weeks frequency, in its surficial water layer were conducted measures which included temperature, pH, Eh, suspended matter amount, total and carbonaceous mineralization. Similar measurements were also conducted in other fluvial lakes and Vistula tributaries. Investigations carried proved the general similarity between physical and chemical properties of lakes and watercourses analysed. However, there exists distinct gradient of carbonaceous mineralization from small values in the Vistula channel to high values at the valley edges. PH and Eh parameters in the Old Vistula lake were different than in all other surveyed sites what leads to conclusion that it is fed by deeper groundwaters than in the case of other fluvial lakes and Vistula tributaries, particularly in low water stand times. Acknowledgements: This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution (ICLEA) of the Helmholtz Association.

  13. Time-integrated sampling of fluvial suspended sediment: a simple methodology for small catchments

    NASA Astrophysics Data System (ADS)

    Phillips, J. M.; Russell, M. A.; Walling, D. E.

    2000-10-01

    Fine-grained (<62·5 µm) suspended sediment transport is a key component of the geochemical flux in most fluvial systems. The highly episodic nature of suspended sediment transport imposes a significant constraint on the design of sampling strategies aimed at characterizing the biogeochemical properties of such sediment. A simple sediment sampler, utilizing ambient flow to induce sedimentation by settling, is described. The sampler can be deployed unattended in small streams to collect time-integrated suspended sediment samples. In laboratory tests involving chemically dispersed sediment, the sampler collected a maximum of 71% of the input sample mass. However, under natural conditions, the existence of composite particles or flocs can be expected to increase significantly the trapping efficiency. Field trials confirmed that the particle size composition and total carbon content of the sediment collected by the sampler were representative statistically of the ambient suspended sediment.

  14. Reservoir Characterization, Production Characteristics, and Research Needs for Fluvial/Alluvial Reservoirs in the United States

    SciTech Connect

    Cole, E.L.; Fowler, M.L.; Jackson, S.R.; Madden, M.P.; Raw-Schatzinger, V.; Salamy, S.P.; Sarathi, P.; Young, M.A.

    1999-04-28

    The Department of Energy's (DOE's) Oil Recovery Field Demonstration Program was initiated in 1992 to maximize the economically and environmentally sound recovery of oil from known domestic reservoirs and to preserve access to this resource. Cost-shared field demonstration projects are being initiated in geology defined reservoir classes which have been prioritized by their potential for incremental recovery and their risk of abandonment. This document defines the characteristics of the fifth geological reservoir class in the series, fluvial/alluvial reservoirs. The reservoirs of Class 5 include deposits of alluvial fans, braided streams, and meandering streams. Deposit morphologies vary as a complex function of climate and tectonics and are characterized by a high degree of heterogeneity to fluid flow as a result of extreme variations in water energy as the deposits formed.

  15. Temporal trends in fluvial-sediment discharge in Ohio, 1950-1987

    USGS Publications Warehouse

    Hindall, S.M.

    1991-01-01

    Long-term fluvial-sediment records of annual suspended-sediment discharge data are available for eight daily suspended-sediment stations operated in Ohio. Graphical and statistical analyses of long-term sediment records indicate that, in general, no long-term (>3- to 5-year) trends are readily apparent in the relation between annual mean suspended-sediment discharge and water discharge in Ohio; however, some short-term, year-to-year changes in that relation occur for Ohio streams. Double-mass curves for five daily suspended-sediment stations and seasonal Kendall analysis of data from eight daily suspended-sediment stations clearly illustrate the lack of any discernible changes in the suspended-sediment-discharge/water-discharge relation or in suspended-sediment concentration for most Ohio streams over the past 36 years. -from Author

  16. Use of sediment-trace element geochemical models for the identification of local fluvial baseline concentrations

    USGS Publications Warehouse

    Horowitz, A.J.; Elrick, K.A.; Demas, C.R.; Demcheck, D.K.

    1991-01-01

    Studies have demonstrated the utility of fluvial bed sediment chemical data in assesing local water-quality conditions. However, establishing local background trace element levels can be difficult. Reference to published average concentrations or the use of dated cores are often of little use in small areas of diverse local petrology, geology, land use, or hydrology. An alternative approach entails the construction of a series of sediment-trace element predictive models based on data from environmentally diverse but unaffected areas. Predicted values could provide a measure of local background concentrations and comparison with actual measured concentrations could identify elevated trace elements and affected sites. Such a model set was developed from surface bed sediments collected nationwide in the United States. Tests of the models in a small Louisiana basin indicated that they could be used to establish local trace element background levels, but required recalibration to account for local geochemical conditions outside the range of samples used to generate the nationwide models.

  17. Quality assurance practices for the chemical and biological analyses of water and fluvial sediments

    USGS Publications Warehouse

    Friedman, Linda C.; Erdmann, David E.

    1982-01-01

    This chapter contains practices used by the U.S. Geological Survey to assure the quality of analytical data for water, fluvial sediment, and aquatic organisms. These practices are directed primarily toward personnel making water quality measurements. Some detail specific quality control techniques, others document quality assurance procedures being used by the Central Laboratories System of the U.S. Geological Survey, and still others describe various statistical techniques and give examples of their use in evaluating and assuring the quality of analytical data. The practices are arranged into eight sections: Analytical Methods Development Procedures, Standard Quantitative Analysis Techniques, Instrumental Techniques, Reference Material, Laboratory Quality Control; Quality Assurance Monitoring; Documentation, Summary, and Evaluation of Data, Materials Evaluation. Each section is preceded by a brief description of the material covered. Similarly within each section, each practice is preceded by a description of its application or scope.

  18. Insight on watershed development along the actively uplifting Mount Lebanon range (Lebanon) from marine and fluvial terraces

    NASA Astrophysics Data System (ADS)

    Lepley, S.; Gomez, F.; Nader, F.

    2005-12-01

    Active uplift in the Mt. Lebanon range results from regional transpression along a ~200-km-long restraining bend within the Dead Sea fault system. Thus, the resultant landscape is characterized by the combined influences of tectonic, eustatic, and climatic controls. Marine terraces in northern Mt. Lebanon range provide significant constraints on regional uplift and, consequently, base level control on watershed development. Detailed geologic mapping reveals at least six coastal terrace levels between the cities of Tripoli and Batroun in northern Lebanon, ranging in elevation from 5 m to 113 m above sea level. The marine terraces are primarily abrasional platforms with little to no sediment cover. However, at certain locations, the terraces comprise of a thick (up to 20 m towards the coast) sedimentary cover that are the result of episodic periods of cut and fill into older Pliocene deposits. The majority of these sediments are well-rounded, cobble-size clasts of limestone cemented by a calcite matrix with occasional clasts of basalt and marine fossils. Travertine formations, fossil remnants, and limestone clasts are available to constrain ages on terrace formations and, in turn, coastal uplift rates. Correlation of terrace heights with Pleistocene sea level variations suggests an average, regional uplift rate of 0.3 m/ka. Fluvial terraces in the northern Mt. Lebanon allow reconstruction of longitudinal profiles that grade into base levels represented by the corresponding marine terraces. Hence, this correlation constrains the ages of fluvial terraces and consequently permits estimates of fluvial erosion. Temporal variations in fluvial transport capacity are suggested by episodic aggradation of massive boulder-size clasts of basalt and dolomite that originate over 20 km upstream. Furthermore, knickpoints in the present-day drainage also appear to correlate with the former base levels. Hence, the retreat of these knickpoints permits assessing the lag time in the response of the fluvial system to base level changes.

  19. Impacts of mire reclamation on dynamics of dissolved nutrients in fluvial systems in the Sanjiang Plain, Northeast China.

    PubMed

    Guo, Yuedong; Song, Changchun; Wang, Lili; Wan, Zhongmei

    2012-11-01

    As an important nutrient reservoir, the mires in the Sanjiang Plain of Northeast China have been suffering from large-scale agriculture reclamation since the 1960s. The effects of the long-term reclamation on the dynamics of the dissolved nutrients in fluvial systems are revealed through surveying the export concentrations of dissolved nitrogen and phosphorus in the natural mire, degraded mire and drainage ditches during the growing seasons in 2009 and 2010. The results show that the mean concentrations of total dissolved nitrogen (TDN, 2.03 ± 0.355 mg l(-1)) are much higher in natural mire than in degraded mire (1.15 ± 0.247 mg l(-1)) and ditches (1.03 ± 0.231 mg l(-1)), and the fraction lessened is primarily the organic part of nitrogen. It indicates that the long-term mire reclamation has led to a significant reduction in TDN concentrations in the surface fluvial system, and has changed the dominant nitrogen components from organic to inorganic formation. In comparison, the concentrations of total dissolved phosphorus (TDP) have no significant difference between natural mire and degraded mire or ditches, which demonstrates that mire reclamation has no impact on TDP export dynamics in the fluvial system. The seasonal dynamics of TDN are strongly correlated to dissolved organic carbon at almost all the sample sites, and mire reclamation does not alter the C : N ratio in the fluvial system, but lowers N : P ratio remarkably. The long-term reclamation exerts distinctly different effects on the export dynamics of TDN and TDP in the fluvial system in the Sanjiang Plain. Specific goals and methods ought to be determined if ecological management and recovery measures are to be carried out. PMID:23072759

  20. Fluvial response to abrupt global warming at the Palaeocene/Eocene boundary.

    PubMed

    Foreman, Brady Z; Heller, Paul L; Clementz, Mark T

    2012-11-01

    Climate strongly affects the production of sediment from mountain catchments as well as its transport and deposition within adjacent sedimentary basins. However, identifying climatic influences on basin stratigraphy is complicated by nonlinearities, feedback loops, lag times, buffering and convergence among processes within the sediment routeing system. The Palaeocene/Eocene thermal maximum (PETM) arguably represents the most abrupt and dramatic instance of global warming in the Cenozoic era and has been proposed to be a geologic analogue for anthropogenic climate change. Here we evaluate the fluvial response in western Colorado to the PETM. Concomitant with the carbon isotope excursion marking the PETM we document a basin-wide shift to thick, multistoried, sheets of sandstone characterized by variable channel dimensions, dominance of upper flow regime sedimentary structures, and prevalent crevasse splay deposits. This progradation of coarse-grained lithofacies matches model predictions for rapid increases in sediment flux and discharge, instigated by regional vegetation overturn and enhanced monsoon precipitation. Yet the change in fluvial deposition persisted long after the approximately 200,000-year-long PETM with its increased carbon dioxide levels in the atmosphere, emphasizing the strong role the protracted transmission of catchment responses to distant depositional systems has in constructing large-scale basin stratigraphy. Our results, combined with evidence for increased dissolved loads and terrestrial clay export to world oceans, indicate that the transient hyper-greenhouse climate of the PETM may represent a major geomorphic 'system-clearing event', involving a global mobilization of dissolved and solid sediment loads on Earth's surface. PMID:23128230

  1. Reconstructing multi-decadal variations in fluvial flood risk using atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Wilby, Robert L.; Quinn, Nevil W.

    2013-04-01

    SummaryConventional techniques for quantifying and then managing flood risks are invalid under 'non-stationary' climate conditions. Trend detection and attribution are problematic given that the outcome depends on the start and end date of the record, choice of index and test statistic, assumed behaviour of the system, and many non-climatic confounding factors. Analyses are further hampered by short and non-homogeneous flow records. In this paper, we use an objective weather classification scheme to reconstruct the atmospheric drivers of fluvial flood occurrence and magnitude in England, Scotland and Wales since the 1870s. We demonstrate the index using long (>50 year) annual maximum (AMAX) and peak over threshold (POT) flood records for 114 stations. Synoptic indices show modest skill at hindcasting multi-decadal variations in flood frequency at national, regional and catchment scales, but not for flood magnitudes. Flood rich episodes are identified in the periods 1908-1934, 1977-1988 and from 1998 onwards. We find that five weather types account for 68% of flood occurrence, and just three types were linked to the most widespread winter floods. These flood-generating systems generally show no sustained changes in frequency, persistence, relative contribution, or rain-bearing properties since the 1930s. However, there are emergent patterns in the day-to-day persistence (declining) and mean precipitation yield (rising) of anticyclonic weather types that merit further investigation. Based on our evaluation, we recommend use of objective weather indices derived from observed atmospheric pressure patterns when interpreting fluvial flood risk linked to climate drivers.

  2. Interacting effects of climate and agriculture on fluvial DOM in temperate and subtropical catchments

    NASA Astrophysics Data System (ADS)

    Graeber, D.; Goyenola, G.; Meerhoff, M.; Zwirnmann, E.; Ovesen, N. B.; Glendell, M.; Gelbrecht, J.; Teixeira de Mello, F.; González-Bergonzoni, I.; Jeppesen, E.; Kronvang, B.

    2015-01-01

    Dissolved organic matter (DOM) is an important factor in aquatic ecosystems, which is involved in a large variety of biogeochemical and ecological processes and recent literature suggests that it could be strongly affected by agriculture in different climates. Based on novel monitoring techniques, we investigated the interaction of climate and agriculture effects on DOM quantity and molecular composition. To examine this, we took water samples over two years in two paired intensive and extensive farming catchments in each Denmark (temperate climate) and Uruguay (subtropical climate). We measured dissolved organic carbon (DOC) and nitrogen (DON) concentrations and DOC and DON molecular fractions with size-exclusion chromatography. Moreover, we assessed DOM composition with absorbance and fluorescence measurements, as well as parallel factor analysis (PARAFAC). We also calculated DOC and DON loads based on daily discharge measurements, as well as measured precipitation and air temperature. In the catchments in Uruguay, the fluvial DOM was characterized by higher temporal variability of DOC and DON loads which were clearly related to a higher temporal variability of precipitation and a DOM composition with rather plant-like character relative to the Danish catchments. Moreover, we consistently found a higher temporal variability of DOC an DON loads in the intensive farming catchments than in the extensive farming catchments, with the highest temporal variability in the Uruguayan intensive farming catchment. Moreover, the composition of DOM exported from the intensive farming catchments was always complex and related to microbial processing in both Denmark and Uruguay. This was indicated by low C : N ratios, several spectroscopic DOM composition indexes and the PARAFAC fluorescence components. We propose that the consistent effect of intensive farming on DOM composition and the temporal variability of DOC and DON loads is related to similarities in the management of agriculture, which may have wide-scale implications for fluvial DOM composition, as well as related ecological processes and biogeochemical cycles.

  3. Stratigraphic controls on facies characteristics and petrophysical attributes in fluvial channel sandstones

    SciTech Connect

    Cross, T.A.; Kusumanegara, Y. [Colorado School of Mines, Golden, CO (United States)

    1995-08-01

    Previous studies of fluvial, alluvial fan and lacustrine strata have documented changes in stratigraphic architecture and facies that occur as a function of accommodation. One of the most pervasive change of this type is the degree to which original geomorphic elements, such as bedforms, bars and other macroforms, are preserved. In high accommodation conditions, a greater diversity and greater diversity and greater proportion of original bedforms are preserved in continental strata. The same continental environment will be represented by lower facies diversity, and more amalgamated and cannibalized bedforms under conditions of low accommodation. This study sought to determine whether these predictable changes in facies would be accompanied by changes in porosity and permeability, and whether very subtle changes in facies would have marked changes in porosity and permeability. We also wished to identify how subtle variations in facies would affect flow of hydrocarbons through reservoirs. To this end, we conducted stratigraphic, facies and petrophysical analyses of fluvial channelbelt sandstones and associated floodplain and lacustrine mudstones in an exhumed oil reservoir of Tertiary age in the Uinta basin, Utah (USA). Through measurements, we determined that visual estimates of the intensity of surface oil staining were an accurate proxy measurement of the pore volume, and all pore volumes were fully filled with dead, waxy oil. Three genetic sequences are exposed in quarry highwalls. Contrary to intuition, the most porous and permeable sandstones characteristic of the lowest unit would not make the most efficient reservoirs because permeability variations are so great they would be difficult to sweep effectively. Channelbelt sandstones of the intermediate accommodation have less variation in permeability, and yet retain sufficient porosity and permeability that they would be more efficient reservoirs.

  4. An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils

    USGS Publications Warehouse

    Mahan, S.A.; Brown, D.J.

    2007-01-01

    There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence dating the equatorial site and semi-arid climate facilitate grain bleaching, while the gentle terrain ensures shallow water columns, low turbidity, and relatively long surface exposures for transported grains prior to deposition and burial. For this study, we focused on dating sandy strata (indicative of high-energy fluvial events) at various positions and depths within a second-order dambo in central Uganda. Blue-light quartz optically stimulated luminescences (OSL) ages were compared with infrared stimulated luminescence (IRSL) and thermoluminescence (TL) ages from finer grains in the same sample. A total of 8 samples were dated, with 6 intervals obtained at ???35, 33, 16, 10.4, 8.4, and 5.9 ka. In general, luminescence ages were stratigraphically, geomorphically and ordinally consistent and most blue-light OSL ages could be correlated with well-dated climatic events registered either in Greenland ice cores or Lake Victoria sediments. Based upon OSL age correlations, we theorize that extreme fluvial dambo events occur primarily during relatively wet periods, often preceding humid-to-arid transitions. The optical ages reported in this study provide the first detailed chronology of dambo sedimentation, and we anticipate that further dambo work could provide a wealth of information on the paleohydrology of Central and Southern Africa. ?? 2006 Elsevier Ltd. All rights reserved.

  5. Microbiological Comparisons within and across Contiguous Lacustrine, Paleosol, and Fluvial Subsurface Sediments

    PubMed Central

    Kieft, T. L.; Fredrickson, J. K.; McKinley, J. P.; Bjornstad, B. N.; Rawson, S. A.; Phelps, T. J.; Brockman, F. J.; Pfiffner, S. M.

    1995-01-01

    Twenty-six subsurface samples were collected from a borehole at depths of 173.3 to 196.8 m in the saturated zone at the Hanford Site in south-central Washington State. The sampling was performed throughout strata that included fine-grained lacustrine (lake) sediments, a paleosol (buried soil) sequence, and coarse-grained fluvial (river) sediments. A subcoring method and tracers were used to minimize and quantify contamination to obtain samples that were representative of subsurface strata. Sediment samples were tested for total organic carbon, inorganic carbon, total microorganisms by direct microscopic counts, culturable aerobic heterotrophs by plate counts, culturable anaerobes by most-probable-number enumeration, basal respiration rates, and mineralization of (sup14)C-labeled glucose and acetate. Total direct microscopic counts of microorganisms were low, ranging from below detection to 1.9 x 10(sup5) cells g (dry weight)(sup-1). Culturable aerobes and anaerobes were below minimum levels of detection in most samples. Direct microscopic counts, basal respiration rates, and (sup14)C-glucose mineralization were all positively correlated with total organic carbon and were highest in the lacustrine sediments. In contrast to previous subsurface studies, these saturated-zone samples did not have higher microbial abundance and activities than unsaturated sediments sampled from the same borehole, the fine-textured lacustrine sediment had higher microbial numbers and activities than the coarse-textured fluvial sands, and the paleosol samples did not have higher biomass and activities relative to the other sediments. The results of this study expand the subsurface microbiology database to include information from an environment very different from those previously studied. PMID:16534940

  6. The demise of the Oligo-Miocene fluvial system of the Levant and its geodynamic significance

    NASA Astrophysics Data System (ADS)

    Vachtman, Dina; Mart, Yossi

    2015-04-01

    The Levant rift system is a linear assemblage of axial rifts and their mountainous flanks that comprises two structurally distinct sections. The southern segment is built of series of secondary axial grabens, which trend northwards and are separated from each other by poorly rifted threshold zones, which is the northern extension of the Red Sea continental break-up. The northern section comprises the SW-trending Karasu - Hatay rifts, from which the Ghab graben branches southwards, which is tectonically attributed to the westward migration of Anatolia. A system of large rivers transected the southern section of the Levant from central Arabia in the east to the Mediterranean Sea in the west during the Oligo-Miocene, leaving behind 5 km thick series of clastic deposits at sea, and sandstones and conglomerates of variable thickness on land. The demise of that fluvial system was gradual, stretching from the late Miocene to the early Pleistocene, where coastal rivers were truncated from their sources due to the growth of segmented rift. The geodynamic process that constrains the development of the rifts of the southern Levant and their elevated flanks is oblique rifting, where several small rifts start the evolution along a weakness zone concurrently, separated by wide and inactive threshold zones. Gradually the rifts grow along their long axes to interconnect, shrinking the threshold zone to their disappearence. Such geodynamic history best accounts for the observations of relicts of late Miocene fluvial deposits on mountaintops, large river beds dated to the late Miocene-early Pliocene, and large marine fan deposits of early Pliocene age, where rivers continued to flow in the threshold zones, but truncated by the emerging rifts.

  7. Fluvial system evolution and environmental changes during the Holocene in the Mue valley (Western France)

    NASA Astrophysics Data System (ADS)

    Lespez, Laurent; Clet-Pellerin, Martine; Limondin-Lozouet, Nicole; Pastre, Jean-François; Fontugne, Michel; Marcigny, Cyril

    2008-06-01

    Geomorphological and palaeoenvironmental research on Holocene sedimentation in the Mue valley provides evidence for fluvial system changes related to climate and human activities in Normandy, a poorly studied area of the Paris basin. The 24-km long valley bottom has been investigated through a systematic survey. It shows an original longitudinal sedimentary pattern in relation with valley morphology and local geological controls. Minerogenic, tufaceous and peaty deposits provide opportunities for multi-proxy analyses and radiocarbon dating control. Sedimentation began around 9500 14C BP with silt deposition in a meandering system. The Boreal and the Lower Atlantic periods (8500-6000 14C BP) were mainly characterized by unlithified calcareous tufa. Locally, these deposits are very thick (7 to 13 m). The tufa formed barrages across the valley bottom, providing an autogenic control on upstream sedimentation. During the Upper Atlantic period (6000-4700 14C BP), the valley experienced a decrease in calcareous sedimentation and the development of organic deposits. At the beginning of the Subboreal (4700-3500 14C BP), peat deposits expanded, especially behind the tufa barrages. The valley bottom was characterized by large marshy areas whereas the regional vegetation was progressively modified by human activities. At the end of the Subboreal (3300-3000 14C BP) the infilling of the valley by calcareous silt was caused by an increase of river activity related to climatic and land use changes. From the Iron Age and Gallo-Roman periods (2800-1700 14C BP), the valley bottom was filled by silty overbank deposits related to an increase of soil erosion. The slopes and river system were once again coupled and the fluvial system functioned as a continuum from upstream to downstream. The alluvial record of the Mue valley reflects a broad regional pattern of environmental changes but presents particular features, which highlight the need of longitudinal studies to take into account spatial and temporal discontinuities of Holocene hydro-sedimentary systems, even in small order valleys.

  8. Enhancing the natural removal of As in a reactive fluvial confluence receiving acid drainage

    NASA Astrophysics Data System (ADS)

    Abarca, M. I.; Arce, G.; Montecinos, M.; Guerra, P. A.; Pasten, P.

    2014-12-01

    Fluvial confluences are natural reactors that can determine the fate of contaminants in watersheds receiving acid drainage. Hydrological, hydrodynamic and chemical factors determine distinct conditions for the formation of suspended particles of iron and aluminum oxyhydroxides. The chemical and physical properties of these particle assemblages (e.g. particle size, chemical composition) can vary according to inflow mixing ratios, hydrodynamic velocity profiles, and chemical composition of the flows mixing at the confluence. Due to their capacity to sorb metals, it is important to identify the optimal conditions for removing metals from the aqueous phase, particularly arsenic, a contaminant frequently found in acid drainage. We studied a river confluence in the Lluta watershed, located in the arid Chilean Altiplano. We performed field measurements and laboratory studies to find optimal mixing ratio for arsenic sorption onto oxyhydroxide particles at the confluence between the Azufre (pH=2, As=2 mg/L) and the Caracarani river (pH=8, As<0.1 mg/L). As the contribution of the acidic stream increased, the concentration of Fe and Al in the solid phase reached a peak at different pHs. Although the optimal pH for As sorption was ~3, the overall maximum removal of As at the confluence, ocurred for pH~4. This is produced because optimal As sorption does not occur necessarily for the highest concentrations of particles being formed. We propose that fluvial confluences could be engineered to enhance the natural attenuation of contaminants. An analogy between confluences and coagulation-flocculation-sedimentation drinking water plants could be used to engineer such intervention.Acknowledgements: Proyecto Fondecyt 1130936 and Proyecto CONICYT FONDAP 15110020

  9. Fluvial landscapes - human societies interactions during the last 2000 years: the Middle Loire River and its embanking since the Middle Ages (France)

    NASA Astrophysics Data System (ADS)

    Castanet, Cyril; Carcaud, Nathalie

    2015-04-01

    This research deals with the study of fluvial landscapes, heavily and precociously transformed by societies (fluvial anthroposystems). It aims to characterize i), fluvial responses to climate, environmental and anthropogenic changes ii), history of hydraulical constructions relative to rivers iii), history of fluvial origin risks and their management - (Program: AGES Ancient Geomorphological EvolutionS of the Loire River hydrosystem). The Middle Loire River valley in the Val d'Orléans was strongly and precociously occupied, particularly during historical periods. Hydrosedimentary flows are there irregular. The river dykes were built during the Middle Ages (dykes named turcies) and the Modern Period, but ages and localizations of the oldest dykes were not precisely known. A systemic and multi-scaled approach aimed to characterize i), palaeo-hydrographical, -hydrological and -hydraulical evolutions of the Loire River, fluvial risks (palaeo-hazards and -vulnerabilities) and their management. It is based on an integrated approach, in and out archaeological sites: morpho-stratigraphy, sedimentology, geophysics, geochemistry, geomatics, geochronology, archaeology. Spatio-temporal variability of fluvial hazards is characterized. A model of the Loire River fluvial activity is developed: multicentennial scale variability, with higher fluvial activity episodes during the Gallo-Roman period, IX-XIth centuries and LIA. Fluvial patterns changes are indentified. Settlement dynamics and hydraulical constructions of the valley are specified. We establish the ages and localizations of the oldest discovered dikes of the Middle Loire River: after the Late Antiquity and before the end of the Early Middle Ages (2 dated dykes), between Bou and Orléans cities. During historical periods, we suggest 2 main thresholds concerning socio-environmental interactions: the first one during the Early Middle Ages (turcies: small scattered dykes), the second during the Modern Period (levees: high quasi-continuous dykes).

  10. Lower Permian fluvial cyclicity and stratigraphic evolution of the northern margin of Gondwanaland: Warchha Sandstone, Salt Range, Pakistan

    NASA Astrophysics Data System (ADS)

    Ghazi, Shahid; Mountney, Nigel P.; Sharif, Sadaf

    2015-06-01

    During the Lower Permian (Artinskian), fluvial conditions prevailed in what is now the Salt Range of northern Pakistan. Deposits of the Warchha Sandstone are characterised by a range of fluvial facies and architectural elements that together record both the proximal and distal parts of a meandering river system that drained the northern margin of Gondwanaland. Stratigraphic units are arranged into vertically stacked fining-upward cycles represented by thin accumulations of channel-lag deposits at their bases, and sandstone-dominated channel fill and thicker accumulations of overbank mudstone at their tops. Sedimentary cyclicity records fluvial system development on a variety of spatial and temporal scales. Overall, the Warchha Sandstone preserves a series of three to ten vertically stacked fining-upward cycles that form part of a larger-scale, third-order sequence that is itself bounded by regionally extensive and laterally correlatable unconformities that were generated in response to combined tectonic and eustatic changes. The sequence-stratigraphic architecture reflects regional palaeogeographic development of the Salt Range region. The small-scale fluvial cycles originated through autogenic mechanisms, predominantly as a result of repeated channel avulsion processes that occurred concurrently with on-going subsidence and the progressive generation of accommodation. Each erosively based fining-upward fluvial cycle is divided into three parts: a lower part of trough cross-bedded conglomerate and coarse sandstone; a middle part of tabular cross-bedded, ripple cross-laminated and horizontally laminated sandstone; and an upper part of predominantly horizontally laminated and massive mudstone. Overall, the Warchha Sandstone records the progradation of a wedge of non-marine strata into a previously shallow-marine depositional setting. The underlying marine Dandot Formation is terminated by a major unconformity that represents a type-I sequence boundary associated with a regional relative sea-level fall and a significant regression of the Tethyan shoreline. The overlying Warchha Sandstone represents the onset of the subsequent lowstand systems tract in which a northward-flowing meandering river system redistributed clastic detritus derived from a tectonically-active source area (the Aravalli and Malani ranges) that lay to the south. This episode of fluvial sedimentation was terminated by a widespread marine transgression recorded by an abrupt upward transition to estuarine and shallow-marine deposits of the overlying Sardhai Formation. This change marks the transition from lowstand deposits to a transgressive system tract.

  11. Dispersion of channel-sediment contaminants in distributary fluvial systems: Application to fluvial tephra and radionuclide redistribution following a potential volcanic eruption at Yucca Mountain

    NASA Astrophysics Data System (ADS)

    Pelletier, Jon D.; DeLong, Stephen B.; Cline, Michael L.; Harrington, Charles D.; Keating, Gordon N.

    2008-02-01

    Predicting the fluvial transport and mixing of channel-sediment contaminants is necessary for assessing and mitigating heavy-metal and nuclear-waste contamination in rivers. The dilution-mixing model is widely used for this purpose in tributary channel systems that transport contaminants as bed-material load without significant overbank sedimentation. Here a more general, three-dimensional (3D) contaminant transport numerical model is developed and tested based on bed scour, turbulent mixing of contaminant material with uncontaminated channel-bed sediments, and re-deposition of the mixture by the cumulative effect of many flood events. First, the model is applied to a synthetic alluvial-fan environment downstream from a localized contaminant source in order to illustrate the model behavior. Second, the model is validated against measured tephra concentrations in channels downstream from the Lathrop Wells scoria cone volcano, a localized source of basaltic tephra to downstream channels otherwise comprised of non-basaltic sediments. Third, the model is applied to the problem of predicting the concentration of radionuclide-bound tephra in channels downstream from the proposed nuclear-waste repository at Yucca Mountain, Nevada, in the event of a volcanic eruption through the repository. Contaminated tephra is mobilized from the landscape in this model using threshold criteria for hillslope gradient and channel stream power. Mobilized contaminated tephra is mixed with uncontaminated channel-bed sediments using the contaminant transport model and deposited in channels of the Fortymile Wash alluvial fan where the residents nearest to the proposed repository live. The results of twenty Monte Carlo simulations of eruption fallout and post-eruption redistribution corresponding to a range of wind conditions and eruption magnitudes provide information on the mean and variability of contaminated tephra concentrations to be expected in channels of the Fortymile Wash alluvial fan in the event of an eruption. Mean tephra concentrations are approximately 1% but vary from nearly zero to as high as 26%, reflecting the combined effects of wind direction, eruption magnitude, and dilution of tephra with uncontaminated channel-bed sediments during transport.

  12. The Atlas of Natural Hazards and Risks of Austria: first results for fluvial and pluvial floods

    NASA Astrophysics Data System (ADS)

    Mergili, Martin; Tader, Andreas; Glade, Thomas; Neuhold, Clemens; Stiefelmeyer, Heinz

    2015-04-01

    Incoherent societal adaptation to natural processes results in significant losses every year. A better knowledge of the spatial and temporal distribution of hazards and risks, and of particular hot spots in a given region or period, is essential for reducing adverse impacts. Commonly, different hazard and risk estimations are performed within individual approaches based on tailor-made concepts. This works well as long as specific cases are considered. The advantage of such a procedure is that each individual hazard and risk is addressed in the best possible manner. The drawback, however, consists in the fact that the results differ significantly in terms of quality and accuracy and therefore cannot be compared. Hence, there is a need to develop a strategy and concept which uses similar data sources of equivalent quality in order to adequately analyze the different natural hazards and risks at broader scales. The present study is aiming to develop such a platform. The project Risk:ATlas focuses on the design of an atlas visualizing the most relevant natural hazards and, in particular, possible consequences for the entire territory of Austria. Available as a web-based tool and as a printed atlas, it is seen as a key tool to improve the basis for risk reduction, risk adaptation and risk transfer. The atlas is founded on those data sets available for the entire territory of Austria at a consistent resolution and quality. A 1 m resolution DEM and the official cadastre and building register represent the core, further data sets are employed according to the requirements for each natural hazard and risk. In this contribution, the methodology and the preliminary results for fluvial and pluvial floods and their consequences to buildings for three selected test areas in different types of landscapes (rural, urban and mountainous) are presented. Flooding depths expected for annualities of 30, 100 and 300 are derived from existing data sets for fluvial floods and are computed using the model FloodArea for pluvial floods. Land cover parameters necessary for flood routing are deduced from the official cadastre. The values exposed to each flood scenario are quantified on the basis of objects. In this study, the focus is on buildings, thus the official building register is employed as a major data source. The same register is used to derive the vulnerability of each building with regard to floods. Combining exposed values and vulnerability, the risk for each building, expressed as the expected damage per unit of time, is derived. Furthermore, a methodology to automatically regionalize the object-based hazards, exposures, vulnerabilities and risks to any spatial unit desired is presented. This enables us (i) to adapt the web-based atlas to different zooming levels and to flexibly react to (ii) the needs of the users of the atlas and (iii) the availability of reference data for validation of the analyses. The next steps will include (1) extending the analyses for fluvial and pluvial floods to the entire territory of Austria, employing advanced computational techniques such as the use of a cluster; (2) deriving hazards, exposures, vulnerabilities and risks related to a variety of other hazardous processes as well as to chains and combinations of processes (multi-hazard); (3) considering the consequences of hazardous processes not only for buildings, but also for infrastructures and even humans; and (4) elaborating future scenarios, based on possible environmental (including climatic) and socio-economic changes.

  13. Developing an Understanding of Vegetation Change and Fluvial Carbon Fluxes in Semi-Arid Environments

    NASA Astrophysics Data System (ADS)

    Puttock, A. K.; Dungait, J.; Bol, R.; MacLeod, C. J.; Brazier, R.

    2011-12-01

    Dryland environments are estimated to cover around 40% of the global land surface (Okin et al, 2009) and are home to approximately 2.5 billion people (Reynolds et al. 2007). Many of these areas have recently experienced extensive land degradation. One such area and the focus of this project is the semi-arid US Southwest, where degradation over the past 150 years has been characterized by the invasion of woody vegetation into grasslands. Transition from grass to woody vegetation results in a change in ecosystem structure and function (Turnbull et al, 2008). Structural change is typically characterised by an increased heterogeneity of soil and vegetation resources, associated with reduced vegetation coverage and an increased vulnerability to soil erosion and the potential loss of key nutrients to adjacent fluvial systems. Such loss of resources may impact heavily upon the amount of carbon that is sequestered by these environments and the amount of carbon that is lost as the land becomes more degraded. Therefore, understanding these vegetation transitions is significant for sustainable land use and global biogeochemical cycling. This project uses an ecohydrological approach, monitoring natural rainfall-runoff events over six bounded plots with different vegetation coverage. The experiment takes advantage of a natural abundance stable 13C isotope shift from C3 piñon-juniper (Pinus edulis-Juniperus monosperma) mixed stand through a C4 pure-grass (Bouteloua eriopoda) to C3 shrub (Larrea tridentate). Data collected quantify fluvial fluxes of sediment and associated soil organic matter and carbon that is lost from across the grass-to-shrub and grass-to-woodland transition (where change in space is taken to indicate a similar change through time). Results collected during the 2010 and 2011 monsoon seasons will be presented, illustrating that soil and carbon losses are greater as the ecosystem becomes more dominated by woody plants. Additionally this project utilises novel biogeochemical techniques, using stable 13C isotope and lipid biomarker analyses, to trace and partition fluvial soil organic matter and carbon fluxes during these events. Results show that biomarkers specific to individual plant species can be used to define the provenance of carbon, quantifying whether more piñon or juniper-derived carbon is mobilised from the upland plots, or whether more Larrea tridentate carbon is lost when compared to bouteloa eripoda losses in the lowlands. The combined approach of monitoring carbon fluxes and tracing types of carbon shows great promise for improved understanding of carbon dynamics in areas subject to rapid vegetation change. References Okin, G. S., A. J. Parsons, J. Wainwright, J. E. Herrick, B. Bestelmeyer, T., D. C. Peters, and E. L. Fredrickson. 2009. Do Changes in Connectivity Explain Desertification? Bioscience 59:237-244. Reynolds JF, et al. 2007. Global desertification: Building a science for dryland development. Science 316: 847-851. Turnbull, L., J. Wainright, and R. E. Brazier. 2008. A conceptual framework for understanding semi-arid land degradation: ecohydrological interactions across multiple-space and time scales. Ecohydrology 1:23-34.

  14. Ground Penetrating Radar Field Studies of Planetary Analog Geologic Settings: Impact Ejecta, Volcanics, and Fluvial Terrains

    NASA Astrophysics Data System (ADS)

    Russell, P. S.; Grant, J. A.; Carter, L. M.; Garry, W.; Williams, K. K.; Morgan, G. A.; Daubar, I.; Bussey, B.

    2012-12-01

    Ground-Penetrating Radar (GPR) data from terrestrial analog environments can help constrain models for evolution of the lunar and martian surfaces, aid in interpretation of orbital SAR data, and help predict what might be encountered in the subsurface during future landed scientific or engineering operations. Results and interpretations presented here from impact ejecta (Barringer Meteorite Crater), volcanic deposits (Northern Arizona cinders overlying lavas, columnar-jointed Columbia River flood basalts, Hawaii lava flows), and terrains influenced by fluvial-related activity (channeled scablands megaflood bar, Mauna Kea glacio-fluvial deposits) focus on defining the radar "fingerprint" of geologic materials and settings that may be analogous to those found on the Moon and Mars. The challenge in using GPR in geologic investigations is the degree to which different geologic features and processes can be uniquely identified and distinguished in the data. Our approach to constraining this is to qualitatively and quantitatively characterize GPR signatures of different geological environments and to compare them with "ground-truth" observations of subsurface exposures immediately adjacent or subjacent to our GPR transects. Several sites were chosen in each field area based on accessibility, visual access to the subsurface, and presence of particular geologic features of interest. The interpreted distribution of blocks in impact ejecta at Meteor Crater, using a 400 MHz antenna (wavelength of 75 cm) is 1.5-3 blocks per m^3 in the upper 1 m (and 0.5-1 blocks per m^3 in the upper two meters), which is close to the in situ measured block distribution of 2-3 blocks larger than 0.25-0.30 m per m^3. This is roughly the detection limit to be expected from the ?/3 resolution approximation of radar wavelength and indicates that the 400 MHz GPR is characterizing the block population in ejecta. While megaflood bar deposits are also reflector-rich, individual reflectors are in general more easily distinguished. At multiple sites, cinders appear smoothly, regularly layered, and allow for excellent GPR penetration. Consequently, the often rough relief of underlying lava flows is discernable, allowing thickness and volume estimates to be made, as well as giving some idea of structure within/on the buried flow. Alternations of massive and clinkery horizons within a'a' flows are detected, as are features representing the interface of overlapping pahoehoe flows (likely due to relatively high relief and fracturing associated with squeeze-ups, etc). Accumulations of gravel, pebbles, and fines derived from lavas and cinders and emplaced by alluvial and mass-wasting processes (along the margins of Apollo Valley, Mauna Kea) appear similar to the pure cinders, as it is likely the same porosity and grain-size characteristics that cause layered GPR reflections. In any case, such layers allow interpretation of how successive events filled in surface relief of the underlying (lava) substrate. GPR data of the interior fill of western Apollo Valley reveals relatively flat reflectors in the along-valley direction and inter-fingering, pinching-out, and dome- and trough-shaped reflectors in the cross-valley direction, indicating accumulation by multiple overlapping lobes coming down the valley, possibly due to multiple fluvial events over time.

  15. Evidences of Paleoearthquakes in Palaeolithic settlements within fluvial sequences of the Tagus Basin (Madrid, Central Spain).

    NASA Astrophysics Data System (ADS)

    Silva, Pablo G.; Rodríguez Pascua, M. A.; Pérez López, R.; Giner Robles, J. L.; Roquero, E.; Tapias, F.; López Recio, M.; Rus, I.; Morin, J.

    2010-05-01

    Multiple evidences of soft-sediment to brittle deformation within the Pleistocene fluvial terraces of the Tagus, Jarama, Tajuña and Manzanares river valleys have been described since the middle 20th Century. Cryoturbation, hydroplastic deformations due to underlying karstic collapses or halokinesis on the substratum of neogene gypsums, and seismic shaking have been proposed to interpret these structures. These deformations are typically concentrated in the +18-20 m terrace levels, and closely linked to well-known Palaeolithic sites, in some cases overlaying and/or affecting true prehistoric settlements (i.e. Arganda, Arriaga and Tafesa sites) within the Jarama and Manzanares valleys. The affected settlements typically display acheulian lithic industry linked to the scavenging of large Pleistocene mammals (i.e. Elephas antiquus). Commonly, deformational structures are concentrated in relatively thin horizons (10-50 cm thick) bracketed by undeformed fluvial sands and gravels. The soft-sediment deformations usually consist on medium to fine sized sands injected and protruded in overlaying flood-plain clayey silts, showing a wide variety of convolutes, injections, sand-dikes, dish and pillar structures, mud volcanoes, faults and folds, some times it is possible to undertake their 3D geometrical analysis due to the exceptional conservation of the structures (Tafesa). Recent geo-archaeological prospecting on the for the Palaeolithic Site of Arriaga (South Madrid City) conducted during the year 2009, let to find out an exceptional horizon of deformation of about 1.20 m thick. It consisted on highly disturbed and pervasively liquefacted sands, which hardly can be attributed to no-seismic processes. The acheulian lithic industry of the Madrid Region have been classically attributed the Late Middle Pleistocene (< 350 kyr BP), but recent OSL dating indicate that the basal horizons of the +18-20 m fluvial terraces hold ages younger than c.a. 120-100 kyr BP in this zone. All the evidences point to the occurrence of concentrated seismic activity during the OIS 5 (Last Interglaciar) interfering early human activity in the zone. Presently, the Tagus Basin is subject to moderate seismic activity with strongest seismic events not exceeding intensity VI MSK (1954 AD), but most of them related to the Jarama, Tajuña and Tagus river valleys, which are bounded by large linear escarpments carved in Miocene gypsums. These escarpments display a wide variety of brittle and ductile deformations, as well as clear geomorphological indicators of late Quaternary tectonic activity. Considering the recent ESI-2007 Scale, the reported structures indicate the occurrence of larger paleoearthquakes during the Middle-Late Pleistocene of at least local intensity VIII. This study has been supported by the DGPH de la Comunidad de Madrid, AUDEMA S.A. (Proyecto Arriaga-2009). This is a contribution of GQM-AEQUA.

  16. Martian fluvial landforms: a themis perspective after one year at mars

    NASA Astrophysics Data System (ADS)

    Rice, J., Jr.; Christensen, P.; Malin, M.; McEwen, A.; Ruff, S.

    2003-04-01

    THEMIS (Thermal Emission Imaging System) began mapping operations on February 19, 2002 and is providing both visible and infra-red imaging observations of the martian surface at two scales (18 m/p and 100 m/p respectively). IR observations are being conducted during both day and night. IR imagery records temperature variations, which are primarily due to differences in abundances of rocks, indurated materials, sand, and dust on the surface. THEMIS has imaged all of the major outflow channels and valley networks. The source regions for the outflow channels contain large blocks of collapsed chaotic terrain with very coarse (rocky) slopes and talus aprons while the tops of these blocks appear smooth and mantled with finer grained materials (dust) or alternatively the tops of these blocks may be capped by a different material (relatively finer grained than the lower coarser talus producing material). This suggests that the blocks are made of strongly consolidated material capable of eroding into rocky debris. Layering along with cliff and ledge forming members as well as spur and gully morphology is also seen on the chaotic blocks and suggests materials of varying lithologic strengths. THEMIS IR data also indicates that the streamlined islands are composed of pre-existing laterally extensive, layered, weakly consolidated rock. This observation is based upon the fact that the islands do not exhibit coarse talus aprons unlike the chaotic terrain blocks mentioned above. The streamlined islands appear to be primarily erosional landforms and not depositional. No major depositional bedforms (boulder bars, mega ripples, boulder tails) are seen. This observation (lack of depositional bedforms) may be suggesting information on the consolidation and size of sediment transported by the outflow channels. We propose that the overall sediment transported by the floods was derived from layered weakly consolidated materials that break down into relatively fine-grained material that gets washed through the fluvial system. Sediment will flow over longer distances and have lower settling velocities due to the lower acceleration of gravity on Mars. These factors contribute to allowing the sediment to be deposited over very extensive areas and not in discrete sediment packages (bars and fans). It should also be mentioned that MOC imagery does not reveal any depositional bedforms. These observations and interpretations help explain the lack of major depositional bedforms similar to those associated with catastrophic floods on Earth (Channeled Scabland and Iceland). Clearly, coarse material is seen at the Pathfinder site but the large size material (30 cm and up) was transported only short distances 10's of km (Twin Peaks and other knobby outliers and craters). Additionally, younger post diluvial nearby impact craters have also supplied ejecta material to the Pathfinder site. THEMIS imagery has also discovered and mapped two major flows. One is found near the mouth of the northern branch of Kasei Valles. It shows up well in both day and night IR imagery. Ma’adim Vallis has a flow that can be traced over 150 km from its mouth into the floor of Gusev crater. We suggest that these features are hyperconcentrated flows and not lava flows based on their morphology, geologic setting, and lack of nearby volcanic sources. Valley Networks: Valley Networks have also been imaged with THEMIS. The following observations have been noted. Narrow, incised, discontinuous inner channels with finer grained materials seen on the floors of many valley networks such as Bahram and Nanedi Valles. Stripped channel floors suggesting exhumation of the channel. Valley network dissection also appears much more prevalent in some regions (Libya Montes) than has ever been seen before. This suggests prolonged fluvial activity. Fluvial deposits are also seen at the mouths of many valley networks such as Samara Vallis and an unnamed channel. These terminal deposits are interpreted to be fans.

  17. Martian Fluvial Landforms: A THEMIS Perspective After One Year At Mars

    NASA Astrophysics Data System (ADS)

    Rice, J.; Christensen, P.; Malin, M.; McEwen, A.

    2003-04-01

    THEMIS (Thermal Emission Imaging System) began mapping operations on February 19, 2002 and is providing both visible and infra-red imaging observations of the martian surface at two scales (18 m/p and 100 m/p respectively). IR observations are being conducted during both day and night. IR imagery records temperature variations, which are primarily due to differences in abundances of rocks, indurated materials, sand, and dust on the surface. THEMIS has imaged all of the major outflow channels and valley networks. The source regions for the outflow channels contain large blocks of collapsed chaotic terrain with very coarse (rocky) slopes and talus aprons while the tops of these blocks appear smooth and mantled with finer grained materials (dust) or alternatively the tops of these blocks may be capped by a different material (relatively finer grained than the lower coarser talus producing material). This suggests that the blocks are made of strongly consolidated material capable of eroding into rocky debris. Layering along with cliff and ledge forming members as well as spur and gully morphology is also seen on the chaotic blocks and suggests materials of varying lithologic strengths. THEMIS IR data also indicates that the streamlined islands are composed of pre-existing laterally extensive, layered, weakly consolidated rock. This observation is based upon the fact that the islands do not exhibit coarse talus aprons unlike the chaotic terrain blocks mentioned above. The streamlined islands appear to be primarily erosional landforms and not depositional. No major depositional bedforms (boulder bars, mega ripples, boulder tails) are seen. This observation (lack of depositional bedforms) may be suggesting information on the consolidation and size of sediment transported by the outflow channels. We propose that the overall sediment transported by the floods was derived from layered weakly consolidated materials that break down into relatively fine-grained material that gets washed through the fluvial system. Sediment will flow over longer distances and have lower settling velocities due to the lower acceleration of gravity on Mars. These factors contribute to allowing the sediment to be deposited over very extensive areas and not in discrete sediment packages (bars and fans). It should also be mentioned that MOC imagery does not reveal any depositional bedforms. These observations and interpretations help explain the lack of major depositional bedforms similar to those associated with catastrophic floods on Earth (Channeled Scabland and Iceland). Clearly, coarse material is seen at the Pathfinder site but the large size material (30 cm and up) was transported only short distances 10’s of km (eroded from Twin Peaks and other knobby outliers and craters). Additionally, younger post diluvial nearby impact craters have also supplied ejecta material to the Pathfinder site. THEMIS imagery has also discovered and mapped two major flows. One is found near the mouth of the northern branch of Kasei Valles. It shows up well in both day and night IR imagery. Ma’adim Vallis has a flow that can be traced over 150 km from its mouth into the floor of Gusev crater. We suggest that these features are hyperconcentrated flows and not lava flows based on their morphology, geologic setting, and lack of nearby volcanic sources. Valley Networks have also been imaged with THEMIS. The following observations have been noted: Narrow, incised, discontinuous inner channels with finer grained materials seen on the floors of many valley networks such as Bahram and Nanedi Valles. Stripped channel floors suggesting exhumation of the channel. Valley network dissection also appears much more prevalent in some regions (Libya Montes) than has ever been seen before. This suggests prolonged fluvial activity. Fluvial deposits are also seen at the mouths of many valley networks such as Samara Vallis and an unnamed channel. These terminal deposits are interpreted to be fans. Gusev Crater is a candidate MER landing site and THEMIS is providing new information on this

  18. Inputs and Fluvial Transport of Pharmaceutical Chemicals in An Urban Watershed

    NASA Astrophysics Data System (ADS)

    Foster, G. D.; Shala, L.

    2006-05-01

    Pharmaceuticals and personal care products (PPCPs) are classes of emerging chemical contaminants thought to enter the aquatic environment primarily through wastewater treatment plant (WTP) discharges. As the use of drugs is expected to rise with the aging demographics of the human population and with more river water being diverted to meet potable water demands, the presence of PPCPs in surface water is becoming an issue of public concern. The intent of our study was to quantify potential WTP inputs of PPCPs to rivers in the Wasington, DC (USA) region, and to investigate the fluvial transport of PPCPs in the Anacostia River (AR), the mainstem of a highly contaminated urban watershed in Washington, DC. The approach was to sample WTP water at various stages of treatment, and to measure seasonal concentrations of PPCPs in fluvial transport in the AR. Surface water from the AR was collected through the use of automated samplers during normal flow and storm flow regimes near the head of tide of the AR, just upstream from the confluence of the Northeast (NE) and Northwest (NW) Branches, the two prominent drainages in the watershed. The water samples were filtered to separate river particles from water, and the filtered water was extracted using solid phase extraction (SPE) cartridges. The filters were extracted by sonication in methanol. The SPE and filter extracts were analyzed for a group of widely distributed PPCPs as trimethylsilyl derivatives by using gas chromatography/mass spectrometry. The most frequently detected PPCPs at WTPs included ibuprofen, caffeine, naproxen and triclosan, which ranged from 45 ?g/L (caffeine) to 5 ?g/L (triclosan) in WTP influent and from 0.08 ?g/L (triclosan) to 0.02 ?g/L (ibuprofen) in effluent water. Similar PPCPs were detected in both the NE and NW Branches of the AR, but higher concentrations on average were observed in the NE Branch, which receives WTP effluent upstream from the sampling point. The incidence of PPCPs correlated with WTP discharge, but other sources appear to exist based on the occurrence of PPCPs in the NW Branch, which does not receive WTP discharge. Surface water concentrations of the PPCPs were only weakly dependent on the flow regime of the Anacosita River, ranging from 10 to 250 ng/L in AR water. PPCPs are transported in surface waters at parts per trillion concentrations throughout the year, but sources to the AR are not confined to WTPs.

  19. Fluvial engineering works in the river bed of the Middle Loire

    NASA Astrophysics Data System (ADS)

    Nabet, Fouzi

    2010-05-01

    Since 1995, the Loire riverbed has been a field of restoration and maintenance. These interventions took place within the Plan Loire Grandeur Nature and consisted of the following points: the protection of the inhabitants against flooding risks (opening of the secondary channels), the preservation of the ecological assets and the elimination of the sinking of the water line at it's lower level. This research occurred in a specific part of the Loire riverbed, which is situated between Nevers and Orleans (on both banks). We tried by using a geomorphologic analysis to put in evidence the impact of the interventions on the evolution of the secondary channels and dikes. The Geographical Information System (GIS) put in place for the studies sector helps the space analysis by the superposition and the comparison of the different layers of information. This information tool helps creating a database, which can be updated and extended. This way, the managers of this site can easily integrate new thematic (ecological, pedagogical, tourism activity…) and benefit from a precise mapping of the intervention's areas and the impact of the restoration works. The main objective of the PhD is to analyse the functioning of hydrological and fluvial dynamics of the river bed of the Middle Loire, particularly in areas covered by maintenance work. These fluvial engineering works aim to improve flow and transfer of sediment in the river bed. This approach will evaluate the effectiveness of such maintenance work. It is necessary to set up a very fine scale model to quantify sediment transfer between secondary and main channels. The situation of secondary channels is contrasted, but the excessive growth of vegetation in some channels triggers their perennial functioning. The fine scale analysis is based on studies on seasonal and inter-annual evolution of secondary channels. Digital Elevation models (DEM), longitudinal profiles and topographic cross-sections integrated GIS help to quantify precisely erosion and sedimentation, according to the hydrological year. This work should be conducted according to hydrological events on the basis of topographical, bathymetric and sedimentary surveys. Therefore, a limited number of sites has been chosen in collaboration with AITL, DIREN Centre, and Conservatoire des Espaces Naturels. The result of the thesis brings tools to the Loire river management.

  20. Fluvial reservoir characterization using topological descriptors based on spectral analysis of graphs

    NASA Astrophysics Data System (ADS)

    Viseur, Sophie; Chiaberge, Christophe; Rhomer, Jérémy; Audigane, Pascal

    2015-04-01

    Fluvial systems generate highly heterogeneous reservoir. These heterogeneities have major impact on fluid flow behaviors. However, the modelling of such reservoirs is mainly performed in under-constrained contexts as they include complex features, though only sparse and indirect data are available. Stochastic modeling is the common strategy to solve such problems. Multiple 3D models are generated from the available subsurface dataset. The generated models represent a sampling of plausible subsurface structure representations. From this model sampling, statistical analysis on targeted parameters (e.g.: reserve estimations, flow behaviors, etc.) and a posteriori uncertainties are performed to assess risks. However, on one hand, uncertainties may be huge, which requires many models to be generated for scanning the space of possibilities. On the other hand, some computations performed on the generated models are time consuming and cannot, in practice, be applied on all of them. This issue is particularly critical in: 1) geological modeling from outcrop data only, as these data types are generally sparse and mainly distributed in 2D at large scale but they may locally include high-resolution descriptions (e.g.: facies, strata local variability, etc.); 2) CO2 storage studies as many scales of investigations are required, from meter to regional ones, to estimate storage capacities and associated risks. Recent approaches propose to define distances between models to allow sophisticated multivariate statistics to be applied on the space of uncertainties so that only sub-samples, representative of initial set, are investigated for dynamic time-consuming studies. This work focuses on defining distances between models that characterize the topology of the reservoir rock network, i.e. its compactness or connectivity degree. The proposed strategy relies on the study of the reservoir rock skeleton. The skeleton of an object corresponds to its median feature. A skeleton is computed for each reservoir rock geobody and studied through a graph spectral analysis. To achieve this, the skeleton is converted into a graph structure. The spectral analysis applied on this graph structure allows a distance to be defined between pairs of graphs. Therefore, this distance is used as support for clustering analysis to gather models that share the same reservoir rock topology. To show the ability of the defined distances to discriminate different types of reservoir connectivity, a synthetic data set of fluvial models with different geological settings was generated and studied using the proposed approach. The results of the clustering analysis are shown and discussed.

  1. The causes and consequences of particle size change in fluvial systems

    NASA Astrophysics Data System (ADS)

    Miller, Kimberly Louise Litwin

    One of the most common features in fluvial environments is the systematic downstream decline in grain size, which is usually attributed to either abrasion - the reduction in sediment size due to attrition of mass - or selective sorting - the size segregation of grains due to their relative transport mobility. Despite the ubiquity of this grain pattern and the extensive research on both of these processes, there remains questions regarding the underlying principles driving abrasion and sorting, as well as the relative contribution of these processes to grain fining. Therefore, a mechanistic understanding of these processes is necessary to observe their direct effect on pattern formation. This dissertation investigates the controls and limits on abrasion and sorting through field studies and laboratory experiments. First, using the well-defined boundary conditions of an alluvial fan, we examine how grain hiding limits gravel sorting by tracking changes in the grain size distribution measured using a novel image-based technique. Further downfan, we compare surface sand fractions measured in the field with those from the lab and show that the gravel-sand sorting profiles are self-similar, suggesting generality in their development. In a second field study, using detailed hand and image-based measurements characterizing size and shape of thousands of grains throughout a watershed, we are able to directly observe the effectiveness of abrasion. We then input these measurements into a simple numerical model to tease apart the contribution of abrasion and sorting to downstream grains size and shape evolution. Finally, we conduct laboratory experiments to isolate the effects of impact energy on abrasion rates and use material properties of the grains to collapse mass loss curves between different lithologies. We measure the grain size distribution of the products of abrasion to show that they are in agreement with expectations from brittle fracture theory. The results from this work indicate that both sorting and abrasion are effective mechanisms in producing downstream grain size patterns. Because grain size exerts a strong control on channel morphology, understanding the controls on particle size change fosters a more complete picture of the fluvial system.

  2. Catalase in fluvial biofilms: a comparison between different extraction methods and example of application in a metal-polluted river.

    PubMed

    Bonnineau, Chloé; Bonet, Berta; Corcoll, Natàlia; Guasch, Helena

    2011-01-01

    Antioxidant enzymes are involved in important processes of cell detoxification during oxidative stress and have, therefore, been used as biomarkers in algae. Nevertheless, their limited use in fluvial biofilms may be due to the complexity of such communities. Here, a comparison between different extraction methods was performed to obtain a reliable method for catalase extraction from fluvial biofilms. Homogenization followed by glass bead disruption appeared to be the best compromise for catalase extraction. This method was then applied to a field study in a metal-polluted stream (Riou Mort, France). The most polluted sites were characterized by a catalase activity 4-6 times lower than in the low-polluted site. Results of the comparison process and its application are promising for the use of catalase activity as an early warning biomarker of toxicity using biofilms in the laboratory and in the field. PMID:21080224

  3. Rates and kinematics of deformations along the eastern Qilian Shan Mountain, NE Tibetan Plateau, constraint by deformed fluvial terraces

    NASA Astrophysics Data System (ADS)

    Hu, X.; Pan, B.; Gao, H.; Hu, Z.; Geng, H.; Cao, B.

    2012-04-01

    We derive slip rates of a series of thrust faults and deforming patterns along the eastern Qilian Shan Mountain by detailed survey of deformed fluvial terraces and OSL dating on the terrace surfaces. The northwest-southeastern treading Qilian Shan Mountain, margining the northeastern Tibetan Plateau, has been uplifting and deforming related to thrust faults bordering the mountain range in the north. By now, the fault thrust rate and how the mountain was uplifted and deformed is poorly documented along the eastern Qilian Shan. In this study, several flights of late Quaternary fluvial terraces along two rivers (Xiying River and Jinta River), sourced from the mountain crest and flowing transecting these thrust faults, are surveyed by differential GPS with the accuracy of lower than 10 centimeters. Meanwhile, the abandonment times of terrace surfaces were dated by OSL dating on the overlying loess above the fluvial deposits. Analysis results of height data show that fluvial terrace surfaces were obviously deformed near these thrust faults, and slip rates of these thrust faults were calculated by deformations and age data. Late Quaternary vertical slip rates of the Huangcheng-Taerzhuang Fault, the KangNingQiao Fault, the NanYing Fault, and the QingDaBan Fault are estimated as 0.15-0.28 mm/a, 0.26-0.47 mm/a, 0.21-0.37 mm/a, and 0.09-0.30 mm/a, respectively. By the geometry of terrace surface height, we find that the hanging-walling planes are slightly warped along these thrust faults, which indicates that the folding amount in the hanging wall is relatively small. This evidence suggests that in the late Quaternary, the deforming of mountain range along the eastern Qilian Shan is accomplished mainly by thrust, and the mountain is uplifted through approximately uniform uplift in hanging-wall planes of the series of thrust faults.

  4. Fluvial to shelfal strata of the Late Cretaceous to Paleogene Dorotea and Tres Pasos Formations, Magallanes Basin, El Calafate, Argentina

    E-print Network

    Waynick, Michael Anthony

    2014-12-31

    , and physical and biogenic sedimentary structures. Sections were measured on a bed-by-bed basis, using the methods of Campbell (1967). Facies were defined based on vertical grain-size trends, the vertical succession of sedimentary structures, and fossil... regional erosion surfaces in the proximal part of the basin dominated by fluvial fill. If preserved, these too would become sequence boundaries in the rock record. Eustatic changes would have formed depositional sequence, but the net accommodation due...

  5. High-Temperature Tolerances of Fluvial Arctic Grayling and Comparisons with Summer River Temperatures of the Big Hole River, Montana

    Microsoft Academic Search

    S. C. Lohr; P A. Byorth; C. M. Kaya; W. P. Dwyer

    1996-01-01

    Critical thermal maximum (CTM) and resistance time to high temperature were determined for juvenile Arctic grayling Thymallus arcticus from the fluvial population of the Big Hole River, Montana. Grayling were tested after acclimation to 8.4, 16.0, and 20.0°C. Thermal tolerances increased with acclimation temperatures; mean CTM was 26.4°C for the 8.4°C acclimation group, 28.5°C for the 16.0°C group, and 29.3°C

  6. Fluvial wood function downstream of beaver versus man-made dams in headwater streams in Massachusetts, USA

    NASA Astrophysics Data System (ADS)

    David, G. C.; DeVito, L. F.; Munz, K. T.; Lisius, G.

    2014-12-01

    Fluvial wood is an essential component of stream ecosystems by providing habitat, increasing accumulation of organic matter, and increasing the processing of nutrients and other materials. However, years of channel alterations in Massachusetts have resulted in low wood loads despite the afforestation that has occurred since the early 1900s. Streams have also been impacted by a large density of dams, built during industrialization, and reduction of the beaver population. Beavers were reintroduced to Massachusetts in the 1940s and they have since migrated throughout the state. Beaver dams impound water, which traps sediment and results in the development of complex channel patterns and more ecologically productive and diverse habitats than those found adjacent to man-made dams. To develop better management practices for dam removal it is essential that we understand the geomorphic and ecologic function of wood in these channels and the interconnections with floodplain dynamics and stream water chemistry. We investigate the connections among fluvial wood, channel morphology, floodplain soil moisture dynamics, and stream water chemistry in six watersheds in Massachusetts that have been impacted by either beaver or man-made dams. We hypothesize that wood load will be significantly higher below beaver dams, subsequently altering channel morphology, water chemistry, and floodplain soil moisture. Reaches are surveyed up- and downstream of each type of dam to better understand the impact dams have on the fluvial system. Surveys include a longitudinal profile, paired with dissolved oxygen and ammonium measurements, cross-section and fluvial wood surveys, hydraulic measurements, and floodplain soil moisture mapping. We found that dissolved oxygen mirrored the channel morphology, but did not vary significantly between reaches. Wood loads were significantly larger downstream of beaver dams, which resulted in significant changes to the ammonium levels. Floodplain soil moisture dynamics revealed that wood loads increased the channel complexity and strengthened connections between the stream channel and floodplain. Future work will continue to explore the complex interconnections between beaver dams, channel morphology, hydraulics, floodplain dynamics and water chemistry.

  7. Using Multivariate Analyses to Assess Effects of Fluvial Type on Plant Species Distribution in a Mediterranean River

    Microsoft Academic Search

    Claudia Angiolini; Alessia Nucci; Flavio Frignani; Marco Landi

    2011-01-01

    We propose a method to assess the distribution of plant assemblages along rivers delimiting homogeneous fluvial types using\\u000a cluster analysis applied to morphological features, quantified with aerial photos and geographic information system software.\\u000a A stratified random sampling design along the elevational gradient was used to analyze riparian plant species. Multivariate\\u000a statistics were applied to detect patterns of variation in the

  8. Integrating field measurements and flume experiments for analysing fluvial bedload transport and channel morphodynamics in steep mountain streams

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.; Laute, Katja; Liermann, Susan

    2013-04-01

    Fluvial bedload transport, temporal storage of material and channel morphodynamics have high importance for sedimentary budgets of steep catchments and steep mountain streams. In addition, headwater catchments and steep mountain streams can be relevant sediment sources for lowland river systems. Since 2004 extended and interdisciplinary field investigations on fluvial bedload transport and channel morphodynamics have been conducted in a number of selected stream segments in supply-limited fluvial systems in the inner Nordfjord (Erdalen and Bødalen drainage basins) in western Norway. A range of different methods and techniques have been used. Field studies in the Erdalen drainage basin (79.5 km2) and the Bødalen drainage basin (60.1 km2) have included (i) continuous channel discharge monitoring, (ii) frequently repeated surveys of channel morphometry and granulometric analyses, (iii) different tracer techniques (painted stones, magnetic tracers), (iv) Helley-Smith and other basket measurements, (v) horizontally installed impact sensors, (vi) underwater video filming and (vii) extended biofilm analyses, including also controlled biofilm growing experiments with fixed baskets in selected channel segments. Additional field studies with impact sensors were carried out in selected transport-limited fluvial systems in the Coast Mountains of British Columbia (Canada) in 2010 and 2011. The field studies have been combined with flume experiments for calibration of field measurements, especially for the calibration of the measurements that have been carried out with impact sensors in Norway and Canada. As a key achievement, the entire range of different bedload component grain sizes can be covered by the applied combination of techniques. The flux of bedload material can be quantified and is related to the spatio-temporal variability of sediment supply / availability within the drainage basins and to temporal sediment storage within the channel systems.

  9. Using the landscape morphometric context to resolve spatial patterns of submerged macrophyte communities in a fluvial lake

    Microsoft Academic Search

    Rosalie Léonard; Pierre Legendre; Martin Jean; André Bouchard

    2008-01-01

    This study investigates the spatial heterogeneity of macrophyte communities in a fluvio-lacustrine landscape. We analysed\\u000a the importance of the geomorphological point\\/bay pattern in structuring aquatic plant assemblages inside a 20-km-long littoral\\u000a segment of a large fluvial lake. The abundance of 21 macrophyte species was surveyed in 232 quadrats along 24 transects perpendicular\\u000a to the lakeshore. Two contrasting plant communities were

  10. Lateglacial/early Holocene fluvial reactions of the Jeetzel river (Elbe valley, northern Germany) to abrupt climatic and environmental changes

    NASA Astrophysics Data System (ADS)

    Turner, Falko; Tolksdorf, Johann Friedrich; Viehberg, Finn; Schwalb, Antje; Kaiser, Knut; Bittmann, Felix; von Bramann, Ullrich; Pott, Richard; Staesche, Ulrich; Breest, Klaus; Veil, Stephan

    2013-01-01

    Mechanisms of climatic control on river system development are still only partially known. Palaeohydrological investigations from river valleys often lack a precise chronological control of climatic processes and fluvial dynamics, which is why their specific forces remain unclear. In this multidisciplinary case study from the middle Elbe river valley (northern Germany) multiple dating of sites (palynostratigraphy, radiocarbon- and OSL-dating) and high-resolution analyses of environmental and climatological proxies (pollen, plant macro-remains and ostracods) reveal a continuous record of the environmental and fluvial history from the Lateglacial to the early Holocene. Biostratigraphical correlation to northwest European key sites shows that river system development was partially out of phase with the main climatic shifts. The transition from a braided to an incised channel system predated the main phase of Lateglacial warming (˜14.6 ka BP), and the meandering river did not change its drainage pattern during the cooling of the Younger-Dryas period. Environmental reconstructions suggest that river dynamics were largely affected by vegetation cover, as a vegetation cover consisting of herbs, dwarf-shrubs and a few larger shrubs seems to have developed before the onset of the main Lateglacial warming, and pine forests appear to have persisted in the river valley during the Younger Dryas. In addition, two phases of high fluvial activity and new channel incision during the middle part of the Younger Dryas and during the Boreal were correlated with changes from dry towards wet climatic conditions, as indicated by evident lake level rises. Lateglacial human occupation in the river valley, which is shown by numerous Palaeolithic sites, forming one of the largest settlement areas of that period known in the European Plain, is assigned to the specific fluvial and environmental conditions of the early Allerød.

  11. Turbidity in the fluvial Gironde Estuary (southwest France) based on 10-year continuous monitoring: sensitivity to hydrological conditions

    NASA Astrophysics Data System (ADS)

    Jalón-Rojas, I.; Schmidt, S.; Sottolichio, A.

    2015-06-01

    Climate change and human activities impact the volume and timing of freshwater input to estuaries. These modifications in fluvial discharges are expected to influence estuarine suspended sediment dynamics, and in particular the turbidity maximum zone (TMZ). Located in southwest France, the Gironde fluvial-estuarine system has an ideal context to address this issue. It is characterized by a very pronounced TMZ, a decrease in mean annual runoff in the last decade, and it is quite unique in having a long-term and high-frequency monitoring of turbidity. The effect of tide and river flow on turbidity in the fluvial estuary is detailed, focusing on dynamics related to changes in hydrological conditions (river floods, periods of low discharge, interannual changes). Turbidity shows hysteresis loops at different timescales: during river floods and over the transitional period between the installation and expulsion of the TMZ. These hysteresis patterns, that reveal the origin of sediment, locally resuspended or transported from the watershed, may be a tool to evaluate the presence of remained mud. Statistics on turbidity data bound the range of river flow that promotes the upstream migration of TMZ in the fluvial stations. Whereas the duration of the low discharge period mainly determines the TMZ persistence, the freshwater volume during high discharge periods explains the TMZ concentration at the following dry period. The evolution of these two hydrological indicators of TMZ persistence and turbidity level since 1960 confirms the effect of discharge decrease on the intensification of the TMZ in tidal rivers; both provide a tool to evaluate future scenarios.

  12. Threshold-dominated fluvial styles in an arid-zone mud-aggregate river: The uplands of Fowlers Creek, Australia

    Microsoft Academic Search

    Gresley A. Wakelin-King; John A. Webb

    2007-01-01

    Fowlers Creek is a mud-aggregate fluvial system. Floodplain muds dominate the river's deposits and consist of silt, fine to very fine quartzose sand, and clay. Up to ?80% of the silts and clays are bound into sand- and silt-sized aggregates and comprise a substantial component (>42%) of the floodplain muds. Mud-aggregate sediments behave like sands during transport, and as a

  13. Agua Caliente Wind/Solar Project at Whitewater Ranch

    SciTech Connect

    Hooks, Todd; Stewart, Royce

    2014-12-16

    Agua Caliente Band of Cahuilla Indians (ACBCI) was awarded a grant by the Department of Energy (DOE) to study the feasibility of a wind and/or solar renewable energy project at the Whitewater Ranch (WWR) property of ACBCI. Red Mountain Energy Partners (RMEP) was engaged to conduct the study. The ACBCI tribal lands in the Coachella Valley have very rich renewable energy resources. The tribe has undertaken several studies to more fully understand the options available to them if they were to move forward with one or more renewable energy projects. With respect to the resources, the WWR property clearly has excellent wind and solar resources. The DOE National Renewable Energy Laboratory (NREL) has continued to upgrade and refine their library of resource maps. The newer, more precise maps quantify the resources as among the best in the world. The wind and solar technology available for deployment is also being improved. Both are reducing their costs to the point of being at or below the costs of fossil fuels. Technologies for energy storage and microgrids are also improving quickly and present additional ways to increase the wind and/or solar energy retained for later use with the network management flexibility to provide power to the appropriate locations when needed. As a result, renewable resources continue to gain more market share. The transitioning to renewables as the major resources for power will take some time as the conversion is complex and can have negative impacts if not managed well. While the economics for wind and solar systems continue to improve, the robustness of the WWR site was validated by the repeated queries of developers to place wind and/or solar there. The robust resources and improving technologies portends toward WWR land as a renewable energy site. The business case, however, is not so clear, especially when the potential investment portfolio for ACBCI has several very beneficial and profitable alternatives.

  14. Regional distribution of wave- and fluvial-dominated deltaic deposits of Olmos formation (upper Cretaceous) in Maverick basin, southwest Texas

    SciTech Connect

    Ambrose, W.; Tyler, N.

    1984-04-01

    Regional subsurface analysis in southwest Texas indicates that the Olmos Formation (Gulfian) was deposited by a complex of wave- and fluvial-dominated delta systems in two depocenters. Sediment influx was from the north and northwest. Five deltaic submits, A through E, were deposited in the western depocenter. Three other deltaic wedges (F, G, H) formed the second depocenter farther east in present-day Frio and LaSalle Counties. Subsidence was greater in the western half of the Maverick basin where thickest (1,300 ft; 395 m) deltaic sediments were deposited. Lower Olmos strata represent a succession from wave-reworked, strike-elongate deltas of subunit A, similar to those of the underlying San Miguel Formation, to fluvial-dominated, dip-elongate deltas of subunits B and C. Extensive (1200 mi/sup 2/ or 3100 km/sup 2/ in Texas) aggradational floodplain deposits of B and C are characterized by diverse electric-log patterns; variation in log character is a response to complex depositional facies on the delta platform. Downdip, toward the Cretaceous shelf edge, delta-plain facies merge with upward-coarsening delta-front sandstones. Uppermost subunits D and E were deposited by a prograding barrier-island system in an interdeltaic embayment marginal to high constructive deltas of the easter depocenter. Lagoonal and fluvial-channel deposits are recognized from cores. Eastward migration of deposition was accompanied by an abrupt change of depositional style in the western depocenter from deltaic to coastal-interdeltaic.

  15. Fluvial transport potential of shed and root-bearing dinosaur teeth from the late Jurassic Morrison Formation

    PubMed Central

    Coenen, Jason J.; Noto, Christopher R.

    2014-01-01

    Shed dinosaur teeth are commonly collected microvertebrate remains that have been used for interpretations of dinosaur feeding behaviors, paleoecology, and population studies. However, such interpretations may be biased by taphonomic processes such as fluvial sorting influenced by tooth shape: shed teeth, removed from the skull during life, and teeth possessing roots, removed from the skull after death. As such, teeth may behave differently in fluvial systems due to their differences in shape. In order to determine the influence of fluvial processes on the preservation and distribution of shed and root-bearing dinosaur teeth, the hydrodynamic behaviors of high-density urethane resin casts of shed and root-bearing Allosaurus and Camarasaurus teeth were experimentally tested for relative transport distances at increasing flow velocities in an artificial fluviatile environment. Results show that tooth cast specimens exhibited comparable patterns of transport at lower velocities, though the shed Camarasaurus teeth transported considerably farther in medium to higher flow velocities. Two-Way ANOVA tests indicate significant differences in the mean transport distances of tooth casts oriented perpendicular to flow (p < 0.05) with varying tooth morphologies and flow velocities. The differences exhibited in the transportability of shed and root-bearing teeth has important implications for taphonomic reconstructions, as well as future studies on dinosaur population dynamics, paleoecology, and feeding behaviors. PMID:24765581

  16. Fusion of Remote Sensing Methods, UAV Photogrammetry and LiDAR Scanning products for monitoring fluvial dynamics

    NASA Astrophysics Data System (ADS)

    Lendzioch, Theodora; Langhammer, Jakub; Hartvich, Filip

    2015-04-01

    Fusion of remote sensing data is a common and rapidly developing discipline, which combines data from multiple sources with different spatial and spectral resolution, from satellite sensors, aircraft and ground platforms. Fusion data contains more detailed information than each of the source and enhances the interpretation performance and accuracy of the source data and produces a high-quality visualisation of the final data. Especially, in fluvial geomorphology it is essential to get valuable images in sub-meter resolution to obtain high quality 2D and 3D information for a detailed identification, extraction and description of channel features of different river regimes and to perform a rapid mapping of changes in river topography. In order to design, test and evaluate a new approach for detection of river morphology, we combine different research techniques from remote sensing products to drone-based photogrammetry and LiDAR products (aerial LiDAR Scanner and TLS). Topographic information (e.g. changes in river channel morphology, surface roughness, evaluation of floodplain inundation, mapping gravel bars and slope characteristics) will be extracted either from one single layer or from combined layers in accordance to detect fluvial topographic changes before and after flood events. Besides statistical approaches for predictive geomorphological mapping and the determination of errors and uncertainties of the data, we will also provide 3D modelling of small fluvial features.

  17. Riparian vegetation patterns in relation to fluvial landforms and channel evolution along selected rivers of Tuscany (Central Italy)

    USGS Publications Warehouse

    Hupp, C.R.; Rinaldi, M.

    2007-01-01

    Riparian vegetation distribution patterns and diversity relative to various fluvial geomorphic channel patterns, landforms, and processes are described and interpreted for selected rivers of Tuscany, Central Italy; with emphasis on channel evolution following human impacts. Field surveys were conducted along thirteen gauged reaches for species presence, fluvial landforms, and the type and amount of channel/riparian zone change. Inundation frequency of different geomorphic surfaces was determined, and vegetation data were analyzed using BDA (binary discriminate analysis) and DCA (detrended correspondence analysis) and related to hydrogeomorphology. Multivariate analyses revealed distinct quantitative vegetation patterns relative to six major fluvial geomorphic surfaces. DCA of the vegetation data also showed distinct associations of plants to processes of adjustment that are related to stage of channel evolution, and clearly separated plants along disturbance/landform/soil moisture gradients. Species richness increases from the channel bed to the terrace and on heterogeneous riparian areas, whereas species richness decreases from moderate to intense incision and from low to intense narrowing. ?? 2007 by Association of American Geographers.

  18. Self-similarity and multifractality of fluvial erosion topography: 2. Scaling properties

    NASA Astrophysics Data System (ADS)

    Veneziano, Daniele; Niemann, Jeffrey D.

    2000-07-01

    In a companion paper [Veneziano and Niemann, this issue] the authors have proposed self-similarity and multifractality conditions for fluvial erosion topography within basins and have shown that topographic surfaces with this property can evolve from a broad class of dynamic models. Here we use the same self-similarity and multifractality conditions to derive geomorphological scaling laws of hydrologic interest. We find that several existing relations should be modified, as they were obtained using definitions of the quantities involved or measurement techniques that are inappropriate under self-similarity. These relations include Hack's law, the power law decay of the distributions of contributing area and main channel length, the scaling of channel slope with contributing area, and the self-similarity condition for river courses. Most results are further generalized by replacing main stream flow length and drainage area with generic measures of basin size. The relations we obtain among properly measured topographic variables have simple universal exponents. For example, the exponent of Hack's law is 0.5, the exponent of the distribution of contributing area is -0.5, and the exponent of the distribution of main stream length is -1.0. We also suggest a stochastic condition of drainage network self-similarity that incorporates topological as well as geometric and hydrologic features and a reformulation of Horton's laws using drained area rather than stream order.

  19. Mechanisms and timescales of fluvial activity at Mojave and other young Martian craters

    NASA Astrophysics Data System (ADS)

    Goddard, Kate; Warner, Nicholas H.; Gupta, Sanjeev; Kim, Jung-Rack

    2014-03-01

    Mojave Crater, and five other relatively young Late Hesperian to Amazonian-age Martian craters exhibit channelized alluvial fans that are sourced from bedrock-eroded catchments. These catchments emerge from the crests of sloping surfaces, suggesting a formation mechanism that involved precipitation. The evidence for fluvial activity at all six craters is restricted to their interiors and the immediate surrounding regions. Detailed mapping at Mojave reveals the highest density of channels, catchments and fans interior to the crater. Similar landforms are identified outside of the crater, but not beyond ~200 km from the rim. Irregular pits on the floor of Mojave, interpreted as degassing structures from hot impact melt, directly superpose several fan surfaces, and partly destroy the fan toes. This suggests that sediment was mobilized immediately after crater formation, while the crater was still hot. Based on the patterns and timing of channel-fan development at all six craters we favor several hypotheses for the precipitation mechanism: (1) snowfall and melt on young, hot impact craters, (2) impact plume precipitation, and (3) degassing of volatiles from impact melt terrain. Scenario (1) suggests a different global or regional climate relative to modern conditions, requiring equatorial and midlatitude snowfall accumulation. Scenarios (2) and (3) do not necessarily require unique climate conditions, as water may have been mobilized from the target or the impactor.

  20. Mechanisms and Timescales of Fluvial Activity at Mojave and other Young Martian Craters

    NASA Astrophysics Data System (ADS)

    Goddard, Kate; Warner, Nicholas; Gupta, Sanjeev; Kim, Jung-Rack

    2014-05-01

    Mojave crater, and five other relatively young Late Hesperian to Amazonian-age martian craters exhibit channelized alluvial fans that are sourced from bedrock-eroded catchments. These catchments emerge from the crests of sloping surfaces, suggesting a formation mechanism that involved precipitation. The evidence for fluvial activity at all six craters is restricted to their interiors and the immediate surrounding regions. Detailed mapping at Mojave reveals the highest density of channels, catchments and fans interior to the crater. Similar landforms are identified outside of the crater, but not beyond ~200 km from the rim. Irregular pits on the floor of Mojave, interpreted as degassing structures from hot impact melt, directly superpose several fan surfaces, and partly destroy the fan toes. This suggests that sediment was mobilized immediately after crater formation, while the crater was still hot. Based on the patterns and timing of channel-fan development at all six craters we favor several hypotheses for the precipitation mechanism: (1) snowfall and melt on young, hot impact craters, (2) impact plume precipitation, and (3) degassing of volatiles from impact melt terrain. Scenario (1) suggests a different global or regional climate relative to modern conditions, requiring equatorial and mid-latitude snowfall accumulation. Scenarios (2) and (3) do not necessarily require unique climate conditions, as water may have been mobilized from the target or the impactor.

  1. Spatial Coupling Among Landslides, Geological Structures, Cataclinal Slopes, and Fluvial Knick Zones in Nepal Himalayas

    NASA Astrophysics Data System (ADS)

    Ojha, T. P.; DeCelles, P. G.

    2014-12-01

    This work aims to identify potential landslide hazard zones in the event of heavy precipitation and seismic activity by examining spatial relationships among existing landslides, earthquake epicenters, fault zones, cataclinal (dip) slopes, anaclinal (escarp) slopes, and river steepness index in the Nepal Himalaya. In order to understand this relationship we have mapped existing landslides on Google Earth images and ESRI base maps, assembled high-resolution digital topographic data by digitizing Nepal Government published topographic maps, and gathered geological data from detailed field mapping and compilation of published geological maps. Slope angle and aspect, and dip direction and angle were extracted from GIS-based digital topographical and geological datasets to develop the new slope maps with cataclinal (dip) and anaclinal (escarp) slope distributions. Longitudinal river profiles were also extracted from high resolution DEM's derived from manually digitized contours. The slope maps with cataclinal and anaclinal slope distributions, earthquake epicenters, major geological structures, longitudinal river profiles, and landslide inventories were visualized in ESRI ArcMap 10.2 to examine the spatial correlation among landslides, fault zones, cataclinal slopes and river steepness index. We have found that landslides are spatially correlated with cataclinal slopes and fluvial knick zones with high steepness index in certain thrust boundaries. The main finding of this work is that the topographic slope threshold alone is a crude measure of landslide susceptibility. The analysis of slope using the geometric relationship among topography and geological bedding is crucial for determining landslide susceptibility in the Himalayan region.

  2. Revealing the natural complexity of fluvial morphology through 2D hydrodynamic delineation of river landforms

    NASA Astrophysics Data System (ADS)

    Wyrick, J. R.; Senter, A. E.; Pasternack, G. B.

    2014-04-01

    Fluvial landforms at the morphological-unit scale (~ 1-10 channel widths) are typically delineated and mapped either by breaking up the one-dimensional longitudinal profile with no accounting of lateral variations or by manually classifying surface water patterns and two-dimensional areal extents in situ or with aerial imagery. Mapping errors arise from user subjectivity, varying surface water patterns when the same area is observed at different discharges and viewpoints, and difficulty in creating a complete map with no gaps or overlaps in delineated polygons. This study presents a new theory for delineating and mapping channel landforms at the morphological-unit scale that eliminates in-field subjective decision making, adds full transparency for map users, and enables future systemic alterations without having to remap in the field. Delineation is accomplished through a few basic steps. First, near-census topographic and bathymetric data are used in a two-dimensional hydrodynamic model to create meter-scale depth and velocity rasters for a representative base flow. Second, expert judgment and local knowledge determine the number and nomenclature of landform types as well as the range of base flow depth and velocity over each type. This step does require subjectivity, but it is transparent and adjustable at any time. Third, the hydraulic landform classification is applied to hydraulic rasters to quickly, completely, and objectively map the planform pattern of laterally explicit landforms. Application of this theory will reveal the true natural complexity, yet systematic organization, of channel morphology.

  3. New microbioassays based on biomarkers are more sensitive to fluvial water micropollution than standard testing methods.

    PubMed

    Esteban, S; Fernández Rodríguez, J; Díaz López, G; Nuñez, M; Valcárcel, Y; Catalá, M

    2013-07-01

    Recent investigations suggest that, despite lack of lethality in validated bioassays, micropollutants in surface waters could induce sublethal toxicity in sensitive taxa, jeopardizing their biological performance and eventually leading to populations' extinction. A broader array of testing species, the miniaturization of bioassays and the development of reliable biomarkers of damage are sought in order to improve ecological relevance and cost efficiency of environmental monitoring. Our aim is to assess the different sensitivity of validated bioassays and new approaches using biomarkers as sensitive endpoints of toxicity in spores of Polystichum setiferum and Danio rerio embryos. Six water samples were collected in Tagus basin in summer and winter. Samples tested induce no acute toxicity in validated methods (algae growth inhibition and daphnia mobility inhibition). Summer water samples induced acute membrane damage (lipid peroxidation) in Danio rerio embryos and hormetic increases in fern spore mitochondrial activity. One of the samples dramatically reduced mitochondrial activity indicating severe acute sublethal phytotoxicity. All the winter samples induced significant decreases in fern spore mitochondrial activity and membrane damage increases in Danio rerio embryo. Furthermore, three samples induced lethal phytotoxicity in fern spores. We conclude that the new microbioassays show a better sensitivity to fluvial water micropollution and confirm the necessity to test critical life stages such as development and provide cost-efficient methods for environmental monitoring. PMID:23618774

  4. Monitoring of fluvial transport in small upland catchments - methods and preliminary results

    NASA Astrophysics Data System (ADS)

    Janicki, Grzegorz; Rodzik, Jan; Chabudzi?ski, ?ukasz; Franczak, ?ukasz; Si?uch, Marcin; St?pniewski, Krzysztof; Dyer, Jamie L.; Ko?odziej, Grzegorz; Maciejewska, Ewa

    2014-06-01

    In April 2011 a study was initiated, financed from resources of the Polish National Science Centre, entitled: ‘Rainstorm prediction and mathematic modelling of their environmental and social-economical effects’ (No. NN/306571640). The study, implemented by a Polish-American team, covers meteorological research, including: (1) monitoring of single cell storms developing in various synoptic situations, (2) detection of their movement courses, and (3) estimation of parameters of their rain field. Empirical studies, including hydrological and geomorphological measurements, are conducted in objects researched thoroughly in physiographic terms (experimental catchments) in the Lublin region (SE Poland), distinguished by high frequency of occurrence of the events described. For comparative purposes, studies are also carried out on selected model areas in the lower course of the Mississippi River valley (USA), in a region with high frequency of summer rainstorms. For detailed studies on sediment transport processes during rainstorm events, catchments of low hydrological rank and their sub-catchments in a cascade system were selected. For the basic, relatively uniform geomorpho logical units distinguished this way, erosion and deposition balance of material transported was determined. The aim of work was to determine influence of weather condition on fluvial transport rate in small catchment with low hydrological order

  5. Detailed mapping of fluvial sand bodies improves perforating strategy at Kern River field

    SciTech Connect

    Kodl, E.J. (Caltex Indonesia, Bakersfield, CA (United States)); Brelih, D.A. (Texaco, Inc., Bakersfield, CA (United States))

    1991-02-01

    The producing sands of the Kern River field were deposited by the ancestral Kern River as a series of stacked, and often interconnected, sand bodies. Individual channel sands combine to create composite sand bodies that range from 5 to 100 ft in thickness and from 100 ft to as much as several miles in lateral extent. This high degree of variability in both the thickness and areal extent of the oil-bearing sands inevitably produces sands not conductive to orderly and predictable, steam displacement. These sand bodies, which alone are not capable of physically or economically supporting a steamflood, may be overlooked or inefficiently perforated. However, careful planning allows for these sands to be more fully exploited when the conditions for natural gravity drainage are optimum. In the Kern River field, this means taking advantage of oil viscosity reductions (preheating) realized when the underlying sand is being actively steamflooded. In addition to the importance of timing, detailed geologic reconstructions of individual sand channels are essential to enable selective perforating of those producers which are best able to effectively produce the sand body. An efficient and timely production program under these conditions demands a high degree of communication between the geologist and the engineer, and insures maximum productivity from sands deposited in a complex fluvial depositional environment. A field study is included.

  6. Fluvial sediments, concretions, evaporates at Hanksville, Utah: An analogue field study for Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Orgel, C.; Battler, M.; Foing, B. H.; Van't Woud, H.; Maiwald, V.; Cross, M.; Ono, A.

    2013-09-01

    On 6th August 2012, Curiosity landed in Gale crater, Mars. Initial measurements and pictures showed sedimentary rocks that had been deposited by fluvial activity, e.g., alluvial fan and stream deposits. Such deposits are common in desert environments on Earth. The goal of the ILEWG EuroMoonMars project (February 23rd-March 9th,2013)was to conduct field studies in order to identify and study environments that are analogous to those that Curiosity has studied and will study at Gale crater. Several field campaigns (EuroGeoMars2009 and DOMMEX/ILEWG EuroMoonMars from November 2009 to March 2010) had been conducted at the Mars Desert Research Station (MDRS) [3] near Hanksville, Utah, in the vicinity of the San Rafael swell. The aim of the ILEWG EuroMoonMars 2013 project was to identify terrestrial analog sites for Curiosity exploration. The stratigraphy of the area consists of Jurassic and Cretaceous strat a[5] of which the Summerville Formation, the Brushy Basin Member of the Morrison Formation, and the Dakota Sandstone were studied. Widespread inverted channels on Mars have been identified through orbiter imagery data [6], e.g., at Gale crater. Concretions also appear to be common on Mars and have been found by the Opportunity rover at Meridiani Planum [4] and the Curiosity rover at Yellowknife Bay (Fig. 1).

  7. Fluvial stacking due to plate collision and uplift during the Early Pleistocene in Cyprus

    NASA Astrophysics Data System (ADS)

    Schirmer, Wolfgang; Weber, Josef; Bachtadse, Valerian; BouDagher-Fadel, Marcelle; Heller, Friedrich; Lehmkuhl, Frank; Panayides, Ioannis; Schirmer, Ursula

    2010-12-01

    Southern Cyprus is situated within a mosaic terrane that has been fragmented between the northward drifting African and Arabian plates and the Eurasian plate. Enormous uplift of the earth mantle in the Tróodos Mountains is explained by two models. The subduction model explains subduction along the Cyprean arc to be the driving force for uplift whereas after the restraining bend model westward squeezing of Cyprus along strike-slip faulting is responsible for the enormous uplift at restraining bends. Since its emergence as an island in early Miocene times, landscape formation on Cyprus has been strongly controlled by this uplift. Until the Plio-Pleistocene, a strait belt separated the southern unroofed ophiolitic core region-the Tróodos Mountains-from the folded Kyrenia range to the north. This former sea basin, nowadays the Mesaoría Basin, is linked with the Tróodos Mountains by a dissected glacis with a thick cover of river deposits. The highest and oldest river deposits (Apalós Formation) were studied in the Vlokkariá hill southwest of Lefkosía. The 45.5 m thick Apalós Formation of Early Pleistocene age exhibits 24 sedimentary units (Fluviatile Series). Their magnetostratigraphical characters align with the Matuyama chron including the Olduvai and Jaramillo subchrons thus comprising about 1.15 Ma within the Early Pleistocene. This fluvial stack indicates a very flat and deeply lying river environment flowing from a slowly uplifting Tróodos hinterland. It happened during the end of Early Pleistocene when the enhanced Tróodos uplift started the dissection of the stacked river plain.

  8. Fluvial inheritances of the Cher River floodplain (region Centre, France) as elements of characterization of hydrological dynamics and their past evolutions

    NASA Astrophysics Data System (ADS)

    Vayssière, Anaëlle; Castanet, Cyril; Gautier, Emmanuèle; Virmoux, Clément

    2015-04-01

    Geomorphological studies of floodplains provide relevant data about evolutions of fluvial landscape over long time-scales and allow a better understanding of palaeo-environnemental evolutions. The Cher River flows from the "Massif Central" to its junction with the Loire River in the South of the "Bassin de Paris". The long-term fluvial evolutions since the LGM of this medium-sized catchment, are not well documented. However, a first prospection revealed a high potential of fluvial archives. The aim of the present work is to provide elements to characterize past fluvial dynamics based on the analysis of inherited landforms (mainly palaeo-channels) and sedimentary bodies located in the floodplain, using hydrogeomorphological methods. Data are acquired through the analysis of DEM LiDAR, geophysical methods (electric tomography) and cores (boreholes) collected in the floodplain. The analysis of DEM LiDAR and morpho-sedimentary observations yields palaeo-hydrographical reconstructions and allows two generations of topographic and sedimentary fluvial inheritances to be identified. Most ancient fluvial landforms correspond to mounds slightly higher than the floodplain level, incised by wide and shallow palaeo-channels. A second fluvial pattern, more recent, is characterized by palaeo-meanders. Measuring the width, the amplitude and the curvature, we show that some of the palaeo-meanders are much larger, wider and more sinuous than the current meanders, showing changes in past flow regime. The analysis of the filling of palaeo-channels allows us to identify firstly the transverse and longitudinal geometry of former channels. These data help us to estimate bank-full discharge of palaeo-channels. Secondly, the morpho-sedimentary analysis highlights their post-abandonment environmental changes. Three main stratigraphic units are identified. (1) At the base, there is medium and coarse sand attributed to fluvial transport. (2) It is overlain by a layer composed of organo-mineral clayey deposits, characteristic of a swampy environment disconnected most of the time from the main river. (3) Finally, the upper part is constituted by a silty layer that may be attributed to an increase in fluvial activity or in erosion dynamics (slope of the catchment, local filling processes …) These first results show a good record of palaeo-environnemental changes in the Cher valley. The comparison with similar works conducted in other catchments of the "Bassin de Paris" shows that these records may describe environmental evolutions during the Pleniglacial, Lateglacial and Holocene. The perspectives of this work is to provide relevant data on the readjustment of the river related with climate changes since the LGM and on the part played by climate changes and ancient societies on the fluvial system during the Holocene.

  9. Use of Archival Sources to Improve Water-Related Hazard Assessments at Volcán de Agua, Guatemala

    NASA Astrophysics Data System (ADS)

    Hutchison, A. A.; Cashman, K. V.; Rust, A.; Williams, C. A.

    2013-12-01

    This interdisciplinary study focuses on the use of archival sources from the 18th Century Spanish Empire to develop a greater understanding of mudflow trigger mechanisms at Volcán de Agua in Guatemala. Currently, hazard assessments of debris flows at Volcán de Agua are largely based on studies of analogous events, such as the mudflow at Casita Volcano in 1998 caused by excessive rainfall generated by Hurricane Mitch. A preliminary investigation of Spanish archival sources, however, indicates that a damaging mudflow from the volcano in 1717 may have been triggered by activity at the neighbouring Volcán de Fuego. A VEI 4 eruption of Fuego in late August 1717 was followed by 33 days of localized 'retumbos' and then a major local earthquake with accompanying mudflows from several 'bocas' on the southwest flank of Agua. Of particular importance for this study is an archival source from Archivos Generales de Centro América (AGCA) that consists of a series of letters, petitions and witness statements that were written and gathered following the catastrophic events of 1717. Their purpose was to argue for royal permission to relocate the capital city, which at the time was located on the lower flanks of Volcán de Agua. Within these documents there are accounts of steaming 'avenidas' of water with sulphurous smells, and quantitative descriptions that suggest fissure formation related to volcanic activity at Volcán de Fuego. Clear evidence for volcano-tectonic activity at the time, combined with the fact there is no mention of rainfall in the documents, suggest that outbursts of mud from Agua's south flank may have been caused by a volcanic perturbation of a hydrothermal system. This single example suggests that further analysis of archival documents will provide a more accurate and robust assessment of water related hazards at Volcán de Agua than currently exists.

  10. Un estudio de las potencialidades del mercado para el consumo de agua purificada de la fuente de Azinyahualco

    Microsoft Academic Search

    Agustín Santiago; Octaviano Juárez; Carlos Bouza

    2008-01-01

    Actualmente la comercialización del agua embotellada ha cobrado importancia en la mayoría de países de América latina, realizando fuertes inversiones en su desarrollo tanto el capital transnacional como los capitales nativos. El presente trabajo presenta un estudio de mercado solicitado por los ejidatarios del poblado Azinyahualco, Municipio de Chilpancingo, estado de Guerrero, México. Dichos ejidatarios pretenden comercializar el agua proveniente

  11. Desarrollo y verificación experimental de un modelo de transporte de solutos en sistemas de distribución de agua potable

    Microsoft Academic Search

    J. C. Fonnegra

    RESUMEN: En años recientes, la calidad del agua en los sistemas de distribución de agua potable ha sido tema recurrente por los especialistas y por las agencias regulatorias debido al creciente número de incidentes de contaminación presentados. La utilización de nuevos modelos de predicción se presenta como una nueva alternativa para mejorar las condiciones de servicio y asegurar una calidad

  12. Llamado a cubrir Beca de investigacin. Uso del agua en Sistemas de Produccin Agrcola del Chaco Semirido.

    E-print Network

    Nacional de San Luis, Universidad

    agua en sistemas de producción agrícola en el Chaco Semiárido mediante modelos funcionales de cultivoLlamado a cubrir Beca de investigación. Uso del agua en Sistemas de Producción Agrícola del Chaco iniciar su carrera enfatizando una aproximación sistémica asistida por el uso de modelos matemáticos. L

  13. Issues with using high-resolution DEMs for fluvial geomorphology modelling

    NASA Astrophysics Data System (ADS)

    Castro, Andres

    2015-04-01

    It is widely recognized that undertaking detailed fluvial morphology studies can be a difficult and expensive task due to the high amount of resources, such as time and highly trained personnel, that such studies requires in order to obtain accurate results. Yet, for a wide range of projects that in one way or another require the understanding fluvial systems, engineers are frequently challenged with the daunting task of managing expenses within tight budgets and expecting high quality results. It is with this perspective that it is often desired to simplify processes while maintaining a high reliability of results. In an attempt to tackle this issue the current PhD research presents an alternative methodology to undertake river geomorphology studies, by applying an automated procedure to model stream power from DEMs generated from high resolution LiDAR data. The main aim of the research is to estimate the stream power distribution along selected UK catchments and link the estimated stream power values to floodplain development processes. The raw LiDAR data, in the form of ASCII text files, used for the study correspond to 1m, 2m and 10m resolutions. During the process of creating the DEM of one of the selected rivers, the River Teme, the presence of a number of "blank spots" within the mosaic was noted. These areas corresponded to NoData zones generated presumably from the deflection of the laser beam on a water surface. Given that the GIS software didn't consider the missing data areas as part of the DEM, even though most of the "blank spots" were located on the river channel, it was necessary to develop a procedure in order to eliminate the NoData zones and correct the DEM, prior to undertaking the hydrological analysis of the catchment, without compromising the quality of the rest of the data. In search of an improved quality of results it has been commonly assumed that the higher resolution of the data the better and more accurate results are to be obtained. In the past much attention was focused on how to obtain and process the high resolution data. Nowadays with the availability of very high resolution spatial data and very powerful hardware it is becoming apparent that the quality and accuracy of results depends greatly of the software performance, as it has been found of the current research. While performing the hydrological analysis on GIS of the aforementioned selected UK rivers it was found that very high (1m or 2m) resolution LiDAR data does not provide of the most accurate representation of the rivers' flow paths. When compared with 10m resolution data it becomes apparent that the "lower" resolution data produces better results than the 1m or 2m data, more adjusted to the river actual path. It is possible to argue that the reason for this resides in limitations of the software itself. It is also necessary to point out that, while the for the current research purposes the 10m resolution data provides of better results, for other applications, such as topographic analyses of the area, very high resolution data (1m or 2m) is probably more adequate.

  14. Lower Permian stems as fluvial paleocurrent indicators of the Parnaíba Basin, northern Brazil

    NASA Astrophysics Data System (ADS)

    Capretz, Robson Louiz; Rohn, Rosemarie

    2013-08-01

    A comprehensive biostratinomic study was carried out with abundant stems from the Lower Permian Motuca Formation of the intracratonic Parnaíba Basin, central-north Brazil. The fossils represent a rare tropical to subtropical paleofloristic record in north Gondwana. Tree ferns dominate the assemblages (mainly Tietea, secondarily Psaronius), followed by gymnosperms, sphenophytes, other ferns and rare lycophytes. They are silica-permineralized, commonly reach 4 m length (exceptionally more than 10 m), lie loosely on the ground or are embedded in the original sandstone or siltstone matrix, and attract particular attention because of their frequent parallel attitudes. Many tree fern stems present the original straight cylindrical to slightly conical forms, other are somewhat flattened, and the gymnosperm stems are usually more irregular. Measurements of stem orientations and dimensions were made in three sites approximately aligned in a W-E direction in a distance of 27.3 km at the conservation unit "Tocantins Fossil Trees Natural Monument". In the eastern site, rose diagrams for 54 stems indicate a relatively narrow azimuthal range to SE. These stems commonly present attached basal bulbous root mantles and thin cylindrical sandstone envelopes, which sometimes hold, almost adjacent to the lateral stem surface, permineralized fern pinnae and other small plant fragments. In the more central site, 82 measured stems are preferentially oriented in the SW-NE direction, the proportion of gymnosperms is higher and cross-stratification sets of sandstones indicate paleocurrents mainly to NE and secondarily to SE. In the western site, most of the 42 measured stems lie in E-W positions. The predominantly sandy succession, where the fossil stems are best represented, evidences a braided fluvial system under semiarid conditions. The low plant diversity, some xeromorphic features and the supposedly almost syndepositional silica impregnation of the plants are coherent with marked dry seasons. Thick mudstones and some coquinites below and above the sandy interval may represent lacustrine facies formed in probably more humid conditions. The taphonomic history of the preserved plants began with exceptional storms that caused fast-flowing high water in channels and far into the floodplains. In the eastern site region, many tree ferns only fell, thus sometimes covering and protecting plant litter and leaves from further fragmentation. Assemblages of the central and western sites suggest that the trees were uprooted and transported in suspension (floating) parallel to the flow. Heavier ends of stems (according to their form or because of attached basal bulbous root mantle or large apical fronds) were oriented to upstream because of inertial forces. During falling water stage, the stems were stranded on riverbanks, usually maintaining the previous transport orientation, and were slightly buried. The perpendicular or oblique positions of some stems may have been caused by interference with other stems or shallow bars. Rare observed stems were apparently waterlogged before the final depositional process and transported as bedload. The differences of interpreted channel orientations between the three sites are expected in a braided fluvial system, considering the very low gradients of the basin and the work scale in the order of tens of kilometers. The mean direction of the drainage probably was to east and the flows apparently became weaker downstream. This study seems to provide reliable data for paleocurrent interpretations, especially considering areas with scarce preserved sedimentary structures.

  15. Remote sensing of rivers: an emerging tool to facilitate management and restoration of fluvial systems

    NASA Astrophysics Data System (ADS)

    Legleiter, C. J.; Overstreet, B. T.

    2013-12-01

    All phases of river restoration, from design to implementation to assessment, require spatially distributed, high-resolution data on channels and floodplains. Conventional field methods are cost prohibitive for large areas, but remote sensing presents an increasingly viable alternative for characterizing fluvial systems. For example, bathymetric maps useful for habitat assessment can be derived from readily available, free or low cost image data, provided depth measurements are available for calibration. In combination with LiDAR, spectrally-based bathymetry can be used to determine bed elevations for estimating scour and fill and/or to obtain topographic input data for morphodynamic modeling. New, water-penetrating green LiDAR systems that measure sub-aerial and submerged elevations could provide a single-sensor solution for mapping riparian environments. Our current research on the Snake River focuses on comparing optical- and LiDAR-based methods for retrieving depths and bed elevations. Multi-sensor surveys from 2012 and 2013 will allow us to evaluate each instrument's capabilities for measuring volumes of erosion and deposition in a dynamic gravel-bed river. Ongoing studies also suggest that additional river attributes, such as substrate composition and flow velocity, could be inferred from hyperspectral image data. In general, remote sensing has considerable potential to facilitate various aspects of river restoration, from site evaluation to post-project assessment. Moreover, by providing more extensive coverage, this approach favors an integrated, watershed perspective for planning, execution, and monitoring of sustainable restoration programs. To stimulate progress toward these objectives, our research group is now working to advance the remote sensing of rivers through tool development and sensor deployment. Bathymetric map of the Snake River, WY, derived from hyperspectral image data via optimal band ratio analysis. Flow direction is from right to left.

  16. The phosphorus content of fluvial suspended sediment in three lowland groundwater-dominated catchments

    NASA Astrophysics Data System (ADS)

    Ballantine, Deborah J.; Walling, Desmond E.; Collins, Adrian L.; Leeks, Graham J. L.

    2008-07-01

    SummaryThis paper reports an investigation of the phosphorus (P) content of fluvial suspended sediment samples collected from three lowland groundwater-dominated agricultural catchments in the UK. In-stream trap samplers were installed at a total of 21 locations in the catchments of the Rivers Frome and Piddle in Dorset and in the Upper Tern in Shropshire, UK. Time-integrated suspended sediment samples ( n = 187) were collected at regular intervals over a period of 22 months and analysed for total phosphorus (TP), inorganic phosphorus (IP), organic phosphorus (OP) and algal available phosphorus (AAP). TP concentrations varied between sampling sites in the Rivers Frome and Piddle, allowing key P inputs to be identified, while fractionation of P assisted in identifying the nature of these inputs. There was also significant variation in both the TP concentration and the concentration of individual fractions between the Frome and Piddle catchments and the Upper Tern. These contrasts were attributed to the differing underlying geologies, since the Frome and Piddle are underlain predominantly by chalk, whilst the Upper Tern is underlain by sandstone, and also to the different soil types present. The TP content of suspended sediment collected from the Frome catchment showed a statistically significant relationship with specific surface area, but this relationship was not found for the remaining catchments. Temporal variation in P concentrations at both the seasonal and event scale was also investigated. Seasonal variations were noted for TP concentrations and for the concentrations of IP, OP and AAP in all the study catchments, but no consistent seasonal patterns were discernible. Maximum and minimum concentrations of the individual fractions occurred during different months in each of the study catchments, suggesting that different controls operated in the individual catchments. Short-term temporal variations in TP concentrations were documented for two high flow events. Concentrations were lower during high flow events than in baseflow, reflecting dilution.

  17. Landscape evolution of the northern Hsuehshan Range in Taiwan inferred from fluvial channel morphology

    NASA Astrophysics Data System (ADS)

    Chen, Cheng-Hung; Shyu, J. Bruce H.

    2015-04-01

    The evolution of topography is fundamentally coupled with changes in river channel networks. Erosion rate of a river system into a landscape depends on many factors, including climate, base level, tectonics and lithology. Most previous studies assumed that river networks and watershed boundaries are stable through time. However, if rivers on both sides of the drainage divide have different erosion rates, the divide may move due to the erosion rate difference. In this study, we used a new method of the fluvial geomorphic index ? to analyze the river networks in the northern Hsuehshan Range of Taiwan. The parameter ? provides a prediction of steady-state elevation for a given point along a channel. By comparing the ? values of river tributaries on both sides of the drainage divide, we can obtain the information of the divide condition. If ? values are similar on both sides of the divide, the boundary is generally stable. By contrast, if ? values are very different on the two sides, the boundary is unstable, and the river systems will migrate toward the high ? side until they achieve a stable configuration. We found that on the same side of the northern Hsuehshan Range main divide, the river basins are generally stable, but the main water divide of the Hsuehshan Range is unstable. Based on the results of ? values, river steepness index (ksn), satellite image analysis, and field investigations, the main drainage divide may move from southeast to northwest at a rate of about 10 mm/yr. This movement is likely produced by the general tectonic setting of the area and the activity of the Northern Ilan structure. From our results, we also propose a mechanism for how rivers interact with each other on both sides of the water divide. We hope this study would provide more information for reconstructing river basins in the past and understanding their developments in the future.

  18. Land Use and Climate Impacts on Fluvial Systems (LUCIFS): A PAGES - Focus 4 (PHAROS) research activity

    NASA Astrophysics Data System (ADS)

    Dearing, John; Hoffmann, Thomas

    2010-05-01

    LUCIFS is a global research program which is concerned with understanding past interactions between climate, human activity and fluvial systems. Its focus is on evaluating the geomorphic impact of humans on landscapes, with a strong emphasis on geomorphological and sedimentological perspectives on mid- to long-term man-landscape interactions. Of particular relevance are aspects of sediment redistribution systems such as non-linear behaviour, the role of system configuration, scale effects, and emergent properties Over the last decade the LUCIFS program has been investigating both contemporary and long-term river response to global change with the principal aims of i)quantifying land use and climate change impacts of river-borne fluxes of water, sediment, C, N and P; ii) identification of key controls on these fluxes at the catchment scale; and iii) identification of the feedback on both human society and biogeochemical cycles of long-term changes in the fluxes of these materials The major scientific tasks of the LUCIFS-program are: • synthesising results of regional case studies • identify regional gaps and encouraging new case studies • addressing research gaps and formulating new research questions • organising workshops and conferences In this paper we present the LUCIFS program within the new PAGES structure. LUCIFS is located in the Focus 4 (PHAROS) dealing with how a knowledge of human-climate-ecosystem interactions in the past can help inform understanding and management today. In conjunction with the other working groups HITE (Human Impacts on Terrestrial Ecosystems), LIMPACS (Human Impacts on Lake Ecosystems) and IHOPE (Integrated History of People on Earth) PHAROS aims to compare regional-scale reconstructions of environmental and climatic processes using natural archives, documentary and instrumental data, with evidence of past human activity obtained from historical, paleoecological and archaeological records.

  19. Characterization of soil thermal, hydrological, and mechanical properties at Musashino fluvial terrace in Fuchu, Japan

    NASA Astrophysics Data System (ADS)

    Saito, H.; Moritani, S.; Kohgo, Y.; Hamamoto, S.; Takemura, T.; Ohnishi, J.; Komatsu, T.; Crest Komatsu Team

    2011-12-01

    The ground source heat pump (GSHP) system, based on heat exchange with the deep subsoil environment, generally operates with higher efficiency than the conventional air-source heat pump system. The GSHP system has received great interest in countries in North America and Western Europe because it can potentially reduce energy consumption and greenhouse gas emission. The GSHP releases heat energy to the subsoil during summer for cooling, while it pumps heat energy from the subsoil during winter for heating. To optimally design and operate GSHP systems, not only heat transport in the subsoil but also the influences of temperature changes on water flow, groundwater quality, and ground deformations need to be accurately simulated. The main objective of this study was to characterize soil thermal, hydrological, and mechanical properties of soils by monitoring subsoil temperature, groundwater level, and ground deformation at one of the potential GSHP installation sites in the Musashino fluvial terrace located in Fuchu-city, Japan. Monitoring instruments including resistance-temperature detectors and displacement transducers were installed inside a 50-m borehole excavated at the study site. Temperature observed at 5 m intervals in the borehole showed (i) that the soil temperature gradually decreased with depth, with the exception of temperature at the 5-m depth, and (ii) average temperatures increased as the average air temperature increased. Readings of the displacement transducers were found to be strongly affected by air temperature changes. Data observed at the borehole will be further evaluated and linked to soil physical properties measured from disturbed and undisturbed soil samples collected at the borehole.

  20. Exploring Predictive Relationships of Fluvial Morphology: Using Shuttle Radar Topography Mission Data

    NASA Astrophysics Data System (ADS)

    Hannon, Mark Thomas

    2011-12-01

    To identify general large-scale patterns (slope, slope change, sinuosity) along a river's course the worldwide SRTM 3 arc-second DEM satellite derived data was analyzed. Longitudinal profiles were calculated for sixteen rivers. This analysis uses auxiliary data sets to develop an understanding of the external and internal influences that are pressed upon and inherent within the lower 100 meters of the river systems. Contradictory to previous findings, the sixteen rivers studied here show that slope and sinuosity are not strongly correlated at the reach scale. The total river's longitudinal profile up to 100 meters, provides an average slope and sinuosity throughout the entire system and increases the correlation between slope and sinuosity (˜0.56). Comparing the entire river's longitudinal profiles also illustrates a threshold of planform sinuosity (>1.6) in which meandering rivers are found. Using this threshold, the Indus, Mississippi, and Fly Rivers are further examined to understand lateral migration rates, the link between meandering rivers and the production of oxbow lakes throughout their floodplain. The slope of three rivers was examined for external controls by overlaying geological data of bedrock type and fault locations. Neotectonics appears to impact the slope and/or sinuosity of the Mississippi, Niger, and Magdalena rivers. Results indicate growth faulting found in the mud-dominated systems of the Mississippi and Niger influences sinuosity. The resulting sinuosity is greatest in regions where these rivers are bound by growth faults. The Magdalena has several regions where the river intersects strike-slip faults, resulting in increased slopes with the more parallel the encounter. River longitudinal profiles can also reveal areas of bedload erosion and deposition. Zones of erosion (sources) and deposition (sinks), and knowing how to locate them, are of great interest to a variety of geoscientists. These predictive relationships will provide future assistance to the field of fluvial morphology.

  1. Architecturally constrained spatial modeling of permeability within a fluvial sandstone body, Cretaceous Acu Formation, Brazil

    SciTech Connect

    Barton, M.D.; Yeh, J.; Angle, E.S. [Univ. of Texas, Austin, TX (United States); Carrasco, B.N.; Becker, M.R. [Petrobras R& D Center, Rio de Janeiro (Brazil)

    1996-08-01

    An outcrop of the Cretaceous Acu Formation was investigated as an analog to a heterogeneous group of reservoirs that have significant potential for reserve growth. In the Potiguar Basin of Brazil, the Acu Formation is a 1000-m-thick clastic unit that accumulated within a series of northeast-trending half-grabens during Cenomanian time as the African and South American continental plates separated. The interval consists of an upward-fining cycle of laterally heterogeneous mudstones, sandstones, and conglomerates deposited by a system of braided to meandering streams during an overall transgressive cycle of sedimentation. Architectural and petrophysical attributes of a sandstone body within this succession were investigated and the information used to construct a geologically realistic model of permeability. The outcrop examined exposes a 10-m-thick, 300-m-wide fluvially deposited sandstone body composed of multiple truncating channel storeys. Storeys are 1- to 5-m-thick, 20- to 240-m-wide, and composed of gently dipping beds. A visual comparison of permeability profiles to stratal architecture indicates that (1) permeabilities are reduced one to three orders of magnitude near bed and channel-storey bounding surfaces and (2) beds are characterized by upward-increasing permeability trends. A spatial model of permeability, consistent with the outcrop observations, was constructed using stratal surfaces to define a two-dimensional chronostratigraphic framework of grids (sequences). Permeability was interpolated between measured values using the sequence boundaries to confine the interpolation. The model will be used as a basis for flow simulation to maximize recovery in the vertically stratified and laterally heterogeneous Acu reservoirs.

  2. The fluvial flux of phosphorus from the UK 1974 - 2012: where has all the phosphorus gone?

    NASA Astrophysics Data System (ADS)

    Worrall, Fred; Howden, Nicholas; Burt, Timothy; Jarvie, Helen

    2015-04-01

    As part of the Harmonised Monitoring Scheme, the UK has been monitoring total phosphorus (TP) and total reactive phosphorus (TRP) concentration at the tidal limit of all major UK rivers since 1974. Over the study period there were over 40,000 measurements of TP from 230 catchments and 160,000 measurements of TRP from 270 catchments. Concentrations of TRP and TP in UK rivers have decreased significantly since 1989, with values now less than 50% of their 1974 values. During this time, the ratio of TRP to TP has increased slightly with TRP now representing 73% of TP. The UK riverine flux of TRP peaked at 70.9 ktonnes P/yr (0.29 tonnes P/km2/yr) in 2000 and reached a minimum in 2011 of 9.3 ktonnes P/yr (0.04 tonnes P/km2/yr). Similarly, for TP, the peak flux occurred in 2001 at 95 ktonnes P/yr, with a minimum in 2011 of 15.8 ktonnes P/yr. A comparison of patterns in P fluxes with catchment land-use, soil types and hydroclimatic factors shows that the fluxes of both TP and TRP are dominantly linked to urban land cover, which we consider to be proxy for sewage inputs. The fluvial fluxes of TRP and TP will be discussed in the light of declining P fertiliser inputs; decreased direct sewage outputs of P; increased transfers of P via food and feed imports; and an increasing UK population.

  3. Assessing downstream variation of fluvial processes for recommending maintenance flows in regulated rivers

    SciTech Connect

    Trush, W.; McBain, S. [McBain and Trush, Arcata, CA (United States); Franklin, R. [Hoopa Valley Tribe, CA (United States)

    1995-12-31

    Potential effects of dams on channel morphology typically decrease downstream as flow and sediment contributions from tributaries return dynamic fluvial processes to the mainstem channel. As part of a multi-agency flow study below Lewiston Dam on the Trinity River, Northern California, we evaluated the river`s downstream geomorphic and riparian vegetation response to experimental high flow releases and natural flooding. Downstream changes in channel bed surface-to-subsurface particle size distribution ratios (D50s/D50ss) and the recurrence of flood peaks that cause incipient channel mobility were two potential criteria for locating and evaluating the downstream influence of Lewiston Dam on alluvial processes. Relatively low D50s/D50ss ratios (1.5) at 10 km (the Gravel Plant site) indicated significant dam influence on alluvial processes this far downstream. By 20.5 km (the Steelbridge site), the D50s/D50ss ratios (1.5 to 6.0) were wide-ranging, and this was typical of sampled alternate bar units for the next 30 km downstream. More bulk samples are being collected within the first 38 km to better define downstream trends and within-alternate bar trends. As the second alluvial criterion, it is characteristic for alluvial rivers to have incipient mobilization of the channel bed at discharges approaching eighty percent of the 1.5 to 2.0 year annual maximum flood stage height (bankfull stage). Recurrence intervals for discharges at incipient motion decreased downstream, achieving this condition within 30 km below Lewiston Dam.

  4. CONTROL ROBUSTO EN SISTEMAS DE POTENCIA MULTIMAQUINAS UTILIZANDO LOGICA DIFUSA Y TEORIAS DE

    E-print Network

    Catholic University of Chile (Universidad Católica de Chile)

    CONTROL ROBUSTO EN SISTEMAS DE POTENCIA MULTIMAQUINAS UTILIZANDO LOGICA DIFUSA Y TEORIAS DE CONTROL determinados aplicando el concepto #12;de función de pertenencia de un conjunto difuso (King, 1977). El

  5. Post-Last Glacial Maximum fluvial incision and sediment generation in the unglaciated Waipaoa catchment, North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Marden, M.; Betts, H.; Palmer, A.; Taylor, R..; Bilderback, E..; Litchfield, N.

    2014-06-01

    Small river systems contribute a significant component of sediment delivered to oceans, but the temporal evolution of fluvially eroded landscapes is needed. A sequence of postglacial terraces in the unglaciated Waipaoa River catchment provides the opportunity to document fluvial incision and sediment flux on an ~ 2000-year timescale since the Last Glacial Maximum (LGM), which has previously only been undertaken for the entire post-LGM period. This study also calculates sediment mass, where previously sediment volume was calculated. Using a 15-m DEM, field mapping and surveying, and tephrochronology, we calculate rates of fluvial incision and sediment volumes excavated during successive age-constrained, postglacial, incision events and correlate these with a framework of inferred climatic events established for New Zealand. We identify seven periods of terrace formation each succeeded by a period of fluvial incision, six in total. Although the magnitude of the response during each incision event and thus the sediment volumes generated varied through time and across subcatchments draining two contrasting lithological terrains, we conclude that incision events were essentially synchronous, at least within the timeframe constrained by the ca. 2000 year interval between successive eruptive airfall events. Slope relaxation processes were simultaneous with incision thereby indicating that both processes were likely climate driven. We identify a period of accelerated fluvial incision ~ 7 mm y- 1 commencing before ca. 14.0 cal. ka BP (during the early postglacial period) and ceasing ca. 7.9 cal. ka BP toward the end of the Early Holocene Warming period. The magnitude of this incision response was significantly higher in subcatchments draining highly erodible lithologies in the higher uplifting parts of the catchment when river bedload was at over capacity. In contrast, within the remainder of subcatchments draining the more resistant lithologies and in areas of lower uplift (and in parts subsiding), incision and sediment generation was moderated by the presence of knickpoints. Overall, since abandonment of the LGM to present day, fluvial incision in the Waipaoa and the adjacent Waimata catchments generated ~ 16.7 km3 of sediment of which ~ 10 km3 (~ 90% of the estimated 35 Mt of glacial-postglacial slope and shelf sediment mass) was potentially available for transport offshore. Of this, 14.08 km3 (7.4 km3 derived from 'upper' and 6.7 km3 from 'remainder' of subcatchments) was excavated from Waipaoa catchment at an average of ~ 0.6 km3 ka- 1 of which ~ 80% was generated by ca. 7.9 cal. ka BP. This potentially validates previous accounts of high rates of offshore sediment flux before 8000 14C YBP (ca. 8877 cal. YBP). Thereafter, for the period mid-Holocene cooling and variability (MHCV) (ca. 6.5 cal. ka BP) until the present day, the rate of incision across all subcatchments slowed to ~ 2 mm y- 1 and generated just ~ 20% of the total sediment volume. In part, this reflected a depletion of available sediment as rivers in the upper subcatchments returned to a steady state and, coincidental with an increase in accommodation space in the rapidly growing coastal floodplain, sediment flux to the marine depocentres was thereby limited.

  6. Detection of fluvial sand systems using seismic attributes and continuous wavelet transform spectral decomposition: case study from the Gulf of Thailand

    NASA Astrophysics Data System (ADS)

    Ahmad, Mirza Naseer; Rowell, Philip; Sriburee, Suchada

    2014-06-01

    Fluvial sands host excellent oil and gas reservoirs in various fields throughout the world. However, the lateral heterogeneity of reservoir properties within these reservoirs can be significant and determining the distribution of good reservoirs is a challenge. This study attempts to predict sand distribution within fluvial depositional systems by applying the Continuous Wavelet Transformation technique of spectral decomposition along with full spectrum seismic attributes, to a 3D seismic data set in the Pattani Basin, Gulf of Thailand. Full spectrum seismic attributes such as root mean square and coherency help to effectively map fluvial systems down to certain depth below which imaging is difficult in the intervals of interest in this study. However, continuous wavelet transform used in conjunction with other attributes by applying visualization techniques of transparency and RGB can be used at greater depths to extract from 3D seismic data useful information of fluvial depositional elements. This workflow may help to identify different reservoir compartments within the fluvial systems of the Gulf of Thailand.

  7. Evolution of Subaerial Coastal Fluvial Delta Island Topography into Multiple Stable States Under Influence of Vegetation and Stochastic Hydrology

    NASA Astrophysics Data System (ADS)

    Moffett, K. B.; Smith, B. C.; O'Connor, M.; Mohrig, D. C.

    2014-12-01

    Coastal fluvial delta morphodynamics are prominently controlled by external fluvial sediment and water supplies; however, internal sediment-water-vegetation feedbacks are now being proposed as potentially equally significant in organizing and maintaining the progradation and aggradation of such systems. The time scales of fluvial and climate influences on these feedbacks, and of their responses, are also open questions. Historical remote sensing study of the Wax Lake Delta model system (Louisiana, USA) revealed trends in the evolution of the subaerial island surfaces from a non-systematic arrangement of elevations to a discrete set of levees and intra-island platforms with distinct vegetation types, designated as high marsh, low marsh, and mudflat habitat. We propose that this elevation zonation is consistent with multiple stable state theory, e.g. as applied to tidal salt marsh systems but not previously to deltas. According to zonally-distributed sediment core analyses, differentiation of island elevations was not due to organic matter accumulation as in salt marshes, but rather by differential mineral sediment accumulation with some organic contributions. Mineral sediment accumulation rates suggested that elevation growth was accelerating or holding steady over time, at least to date in this young delta, in contrast to theory suggesting rates should slow as elevation increases above mean water level. Hydrological analysis of island flooding suggested a prominent role of stochastic local storm events in raising island water levels and supplying mineral sediment to the subaerial island surfaces at short time scales; over longer time scales, the relative influences of local storms and inland/regional floods on the coupled sediment-water-vegetation system of the subaerial delta island surfaces remain the subject of ongoing study. These results help provide an empirical foundation for the next generation of coupled sediment-water-vegetation modeling and theory.

  8. Miocene fluvial-tidal sedimentation in a residual forearc basin of the Northeastern Pacific Rim: Cook Inlet, Alaska case study

    SciTech Connect

    Stricker, G.D.; Flores, R.M. [Geological Survey, Denver, CO (United States)

    1996-12-31

    Cook Inlet in southern Alaska represents a Cenozoic residual forearc basin in a convergent continental margin, where the Pacific Plate is being subducted beneath the North American Plate. This basin accumulated the >6,700-m-thick, mainly nonmarine, Eocene-Pliocene Kenai Group. These rocks contain biogenic coal-bed methane estimated to be as high as 245 TCF. Lignites to subbituminous coals with subsurface R{sub o} ranging from 0.38 to 0.73 percent and the stage of clay-mineral diagenesis and expandibility indicate a thermally {open_quotes}cool{close_quotes} basin. Miocene Tyonek and Beluga Formations compose 65 percent (>4,300 m thick) of the Kenai Group. The Tyonek includes conglomeratic sandstones, siltstones, mudstones, coals, and carbonaceous shales, interpreted as braided- stream deposits. These fluvial deposits are interbecided with burrowed, lenticular, and flaser-bedded sandstones, siltstones, and mudstones, interpreted as tidal deposits. Tyonek framework conglomerates formed in wet alluvial fans incised on paleovalleys of the Chugach terrane. Coal-forming mires are well developed on abandoned braided-stream deposits. Tyonek drainages formed in high-gradient alluvial plains inundated by tides similar to environments in the modern upper Cook Inlet. The upper Miocene Beluga consists of sandstones, siltstones, mudstones, carbonaceous shales, and coals deposited in meandering (low sinuosity) and anastomosed fluvial systems. These fluvial deposits alternated vertically with deposits of coal-forming mires. The Beluga drainages formed in low-gradient alluvial plains. The high-gradient Tyonek alluvial plain was probably controlled by provenance uplift and eustatic change, whereas the low-gradient Beluga alluvial plain was influenced by subdued provenance uplift and rapid basin subsidence. Rapid sedimentation on both these low- and high-gradient alluvial plains, which kept up with subsidence, produced a thermally {open_quotes}cool{close_quotes} basin.

  9. Do river channels decrease in width downstream on Distributive Fluvial Systems? An evaluation of modern mega-fans

    NASA Astrophysics Data System (ADS)

    Espinoza, T. N.; Scuderi, L. A.; Weissmann, G. S.; Hartley, A. J.

    2014-12-01

    Recent studies on aggradational continental sedimentary basins globally show that fluvial deposits in most modern sedimentary basins are dominated Distributive Fluvial Systems (DFS). DFS's are identified by: (1) pattern of channels and floodplain deposits that radiate outward from an apex located where the river enters the sedimentary basin, (2) deposition where an alluvial system becomes unconfined upon entering the sedimentary basin, (3) broadly fan shaped deposit that is convex upward across the DFS and concave upward down-fan, and (4) if the DFS is incised, an intersection point above which the alluvial system is held in an incised valley and below which it distributes sediment across an active depositional lobe. Several papers about DFS hypothesized that rivers on DFS decrease in size down-fan. We are testing this hypothesis through evaluation of LANDSAT and STRM data from large DFS described by Hartley et al (2010). We use ArcGIS to: (1) open the images and merge them together if there are more than one image corresponding to the DFS being studied, (2) use a Maximum Likelihood Analysis in six classes to segment different features on the DFS (e.g. exposed sands, water, vegetation, and other fan environments), (3) isolate the classes that correspond to the active channel belt (e.g., exposed sand bars and water), (4) divide the active channel belt into 1000 m long sections, (5) determine the area of active channel belt in each section, and (6) calculate the average width of the river in each section (e.g., W = area/1000m). We present our result for each DFS river on a graph that shows the change in width downstream. Our final product will be a dataset that contains width versus distance down-fan from the apex for as many of the large DFS from Hartley et al (2010) as possible. If the hypothesis is supported, the decrease in width could have a substantial predictive significance on sandstone geometry in fluvial successions.

  10. Reading, Social Control, and the Mexican Soul in "Al filo del agua"

    E-print Network

    Anderson, Danny J.

    1995-01-01

    Al filo del agua (1947) explora los usos de la lectura y su relación con los mecanismos de control social. Temáticamente, la novela representa el papel de la lectura in 1909-1910 y su potencial subversivo en vísperas de la Revolución Mexicana. En...

  11. Physical and human influences on fluvial water quality in the Tagus river catchment, Portugal

    NASA Astrophysics Data System (ADS)

    Nunes, A.

    2009-04-01

    Rivers are important resources of drinkable water, ecosystems with a high biologic potency and places of entertainment. Water quality at the catchment scale depends on climate, geology, geomorphology, soils and mainly of land use and land cover. Different activities such as agriculture, livestock, industrial and urban drains have promoted the deterioration of the fluvial water quality. The announced climate changes, the increase of food requirements, as well as the urban concentration of people pose new challenges for the assessment and sustainable management of water quality on the catchment scale. At present about 2/3 of portuguese population live near coast, in urban centers. Since the last three decades, the largest part of the marginal agricultural land has been abandoned whilst the most productive soils have experienced an intensification on its productivity. The Tagus river catchment, with an area of 24.850 km2 only in the Portuguese territory, shows very important contrasts in climate, geology, geomorphology, land use and population density. The main objectives of this work are to evaluate and compare the surface water quality in different sub catchments of Tagus river and to contribute to a better understanding of how physical and human factors (such as geology, precipitation, temperature, runoff, land use and land cover and population density) interfere in their spatial-temporal variability. In order to achieve this issue, twenty sub catchments were selected. The chosen catchments show different locations and areas, and a quite long data series of physical, chemical and biology properties of water, such as nitrates, phosphates, dissolved oxygen, total coliforms, etc. Making use of Geographic Information System (GIS) tools, a database was created for each sub-catchment containing all the physical and human characteristics. Afterwards, statistical analysis was carried out by using SPSS programme (11.0 for Windows. One-way analysis of variance and the Tukey multiple comparison procedure was performed in order to assess whether differences in physical and human factors and water properties existed among the selected sub catchments. Other statistical procedures were carried out to determine correlations and dependencies between available data. Obtained results show significant statistical differences (p<0,001) among sub catchments concerning surface water quality. Results allow us to conclude that such water is in good quality, contrary to other water which contains a very high nitrates, phosphates and total coliform levels. The factors which better explain this variability are related to the land use, chiefly when social use is preponderate.

  12. Landscape evolution reconstructions on Mars: a detailed analysis of lacustrine and fluvial terraces

    NASA Astrophysics Data System (ADS)

    Rossato, Sandro; Pajola, Maurizio; Baratti, Emanuele; Mangili, Clara; Coradini, Marcello

    2015-04-01

    Liquid water was flowing on the surface of Mars in the past, leaving behind a wide range of geomorphic features. The ancient major Martian water fluxes vanished about 3.5 Ga. Meteoritic impacts, wind-erosion, gravity-related phenomena, tectonic deformations and volcanic activities deeply altered the landforms during the ages. Hence, the reconstruction of water-shaped landscapes is often complicated. Fluvial and lacustrine terraces analysis and correlation is a useful approach to understand and reconstruct the past changes in Martian landscape evolution. These features are commonly used as reference for the top of water bodies on Earth, since they are void of the uncertainties or errors deriving from erosional or slumping processes that could have acted on the valley flanks or in the plateau, where the hydrological network was carved in. The study area is located in the western hemisphere of Mars, in the Memnonia quadrangle, between latitude 9° 10'-9° 50'South and longitude 167° 0'-167° 30' West and it constitutes a transition region between the southern highlands of Terra Sirenum and the northern lowlands of Lucus Planum. Many water-shaped features have already been described near the study area, the most prominent of them being the Ma'adim Vallis and the Mangala Valles system. Our results derive from the observations and the analysis of HRSC images (12.5 m spatial resolution) and Digital Elevation Models (DEMs) derived from the MEX-HRSC (75 m resolution), that allow the identification of elevation differences up to the tens of meter scale. We were able to reconstruct six main evolutionary stages of a complex hydrologic systems consisting of two main palaeorivers (up to 5 km wide) connected one another by a palaeolake that formed within a meteor crater (~20 km diameter). On the basis of Earth analogs, these stages/terraces should have evolved during a long period of time, at least thousands years long. Furthermore, crater counting date back the deactivation of the system to ca 3.5±0.1 Ga ago, suggesting the presence of a stable environment with subaerial water fluxes during the Late Hesperian, very close to the liquid-water disappearance. Apart from the above mentioned reasons, the increasing interest and ongoing programs of on-site Martian exploration are additional reasons to study fluviolacustrine depositional environments. Together with the technology improvements that lead to more flexible safety constraints for landing/exploring, the possibility to focus on specific and more detailed scientific aspects is enhanced.

  13. Experimental investigation of fluvial incision on Titan by low-velocity sediment impacts

    NASA Astrophysics Data System (ADS)

    Polito, P. J.; Zygielbaum, B. R.; Sklar, L. S.; Collins, G.

    2008-12-01

    Images returned by the Cassini-Huygens mission reveal evidence for widespread fluvial incision in the polar regions of Titan. Dendritic channel networks draining to large lakes and the absence of cratering suggest active incision into Titan's water-ice bedrock surface. Previous work using the saltation-abrasion bedrock incision model suggests that a terrestrial channel transposed to Titan conditions would incise at remarkably similar rates, because the effects of Titan's lower gravity and less-dense sediments are offset by a much lower resistance to abrasion for ice than rock of similar strength. Here we report new laboratory measurements of ice erosion by low-velocity sediment impacts, part of a larger study investigating the temperature dependence of the material properties that control ice erodibility. We measure the energy required to erode a unit volume of ice using drop tests, in which a 110-150 g ice clast falls 5-10 cm onto a 20 cm diameter ice disk, and differences in mass and measurements of ice density are used to calculate the volume eroded. We construct the 10cm thick ice disks using 2-4 mm seed crystals and near-freezing distilled water. After freezing at 253 K a disk is placed in the bottom of a steel cylinder surrounded by dry ice and liquid nitrogen is pumped into the cylinder from below, chilling the ice to near-Titan temperatures for several hours but never submerging the samples (all drop test trials are completed in air). Our preliminary drop test results show that 4 J and 25 J are required to erode 1 cm3 of ice at temperatures of 205 K and110 K respectively, suggesting that ice may be no more than 2-3 times more erodible than previously-tested rocks of similar tensile strengths. A key limitation of this experimental method is the small size of our target disks, which fail catastrophically by through-cracking after several hundred drops. To avoid through-cracking and obtain direct measurements of ice surface erosion, we are preparing new experiments using a large ice block (~1.25x105 cm3) enclosed in an insulated test chamber, and a laser topographic scanning system. The drop-test results will then be used to design ice-flume experiments in a walk-in freezer to investigate controls on rates of ice incision by mobile sediments and the morphodynamics of incising ice channels.

  14. Coastal wetland response to sea level rise in a marine and fluvial estuarine system

    NASA Astrophysics Data System (ADS)

    Alizad, K.; Hagen, S. C.; Morris, J. T.; Bilskie, M. V.; Passeri, D. L.; Medeiros, S. C.

    2014-12-01

    Coastal wetlands are at the risk of losing their productivity under increasing rates of sea level rise (SLR). Studies show that under extreme enough stressors, salt marshes will not have time to establish an equilibrium and may migrate landward (Donnelly and Bertness 2001; Warren and Niering 1993) or become open water. In order to investigate salt marsh productivity under SLR scenarios, an integrated hydrodynamic-marsh model was incorporated to dynamically couple physics and biology. The hydrodynamic model calculates mean high water (MHW) and mean low water (MLW) within the river and tidal creeks by analysis of simulated tidal constituents. The response of MHW and MLW is nonlinear due to local changes in the salt marsh platform elevation and biomass productivity. Spatially-varying MHW and MLW are utilized in a biologic model that is a two-dimensional application of the Marsh Equilibrium Model (Morris et al. 2002) to capture the effects of the hydrodynamics on biomass productivity and accretion. Including accurate marsh table elevations into the model is crucial to obtain accurate biomass productivity results. A lidar-derived Digital Elevation Model (DEM) is corrected by incorporating Real Time Kinematic (RTK) surveying elevation data. Additionally, salt marshes continually adapt themselves to reach an equilibrium, in which there are ideal ranges of relative SLR and depth of inundation to increase biomass productivity (Morris et al. 2002). The inputs of the model are updated using the biomass productivity results at each coupling time step to capture the interaction between the marsh and hydrodynamic models. The hydro-marsh model is used to assess the effects of four projections of SLR (Parris et al., 2012) on salt marsh productivity for the year 2100 for the marine dominated Grand Bay, MS estuary and the fluvial dominated Apalachicola, FL estuary. The results show higher productivity under a low SLR scenario and less productivity under the intermediate low SLR. Most of the salt marshes become flooded and some of them migrate under higher SLR scenarios. These examples show how this tool can be used in any estuarine system to project salt marsh productivity and accretion under sea level change scenarios to better interpret responses and improve restoration and planning management decisions.

  15. Integration of fluvial erosion factors for predicting landslides along meandering rivers

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  16. Geospatial Characterization of Fluvial Wood Arrangement in a Semi-confined Alluvial River

    NASA Astrophysics Data System (ADS)

    Martin, D. J.; Harden, C. P.; Pavlowsky, R. T.

    2014-12-01

    Large woody debris (LWD) has become universally recognized as an integral component of fluvial systems, and as a result, has become increasingly common as a river restoration tool. However, "natural" processes of wood recruitment and the subsequent arrangement of LWD within the river network are poorly understood. This research used a suite of spatial statistics to investigate longitudinal arrangement patterns of LWD in a low-gradient, Midwestern river. First, a large-scale GPS inventory of LWD, performed on the Big River in the eastern Missouri Ozarks, resulted in over 4,000 logged positions of LWD along seven river segments that covered nearly 100 km of the 237 km river system. A global Moran's I analysis indicates that LWD density is spatially autocorrelated and displays a clustering tendency within all seven river segments (P-value range = 0.000 to 0.054). A local Moran's I analysis identified specific locations along the segments where clustering occurs and revealed that, on average, clusters of LWD density (high or low) spanned 400 m. Spectral analyses revealed that, in some segments, LWD density is spatially periodic. Two segments displayed strong periodicity, while the remaining segments displayed varying degrees of noisiness. Periodicity showed a positive association with gravel bar spacing and meander wavelength, although there were insufficient data to statistically confirm the relationship. A wavelet analysis was then performed to investigate periodicity relative to location along the segment. The wavelet analysis identified significant (? = 0.05) periodicity at discrete locations along each of the segments. Those reaches yielding strong periodicity showed stronger relationships between LWD density and the geomorphic/riparian independent variables tested. Analyses consistently identified valley width and sinuosity as being associated with LWD density. The results of these analyses contribute a new perspective on the longitudinal distribution of LWD in a river system, which should help identify physical and/or riparian control mechanisms of LWD arrangement and support the development of models of LWD arrangement. Additionally, the spatial statistical tools presented here have shown to be valuable for identifying longitudinal patterns in river system components.

  17. An experimental study of fluvial processes at asymmetrical river confluences with hyperconcentrated tributary flows

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanfeng; Wang, Ping; Wu, Baosheng; Hou, Suzhen

    2015-02-01

    This paper reports findings from experimental studies of sediment transport and bed morphology at asymmetrical confluences with hyperconcentrated tributary flows in the upper Yellow River. The results indicate that the hyperconcentrated flow confluence can be divided into four hydraulic regions, including the backwater zone above the upstream junction corner, the maximum velocity area, the separation flow zone, and the post-confluence region downstream of the junction corner. The bed morphology also consists of four basic elements, including the sandbar in the backwater zone, the bar in the separation flow zone, the thalweg for flow conveyance and sediment transport, and bars in the reach downstream of the separation zone. The sediment load of the hyperconcentrated flow from the tributary was the most important control on fluvial processes at such confluences. The increase in deposition in the backwater zone as the sediment load increased was almost linear, and the depth of sediment deposition in the backwater zone was approximately normal in distribution. The validity of a conceptual model for discriminating the status of the backwater effect, developed earlier from field data using the relationship between the sediment load and water volume of hyperconcentrated flows, was confirmed by the experiments. Deposition in the reach downstream of the junction, sandbar height in the backwater zone, and the width and length of the separation zone bar all tended to increase as the sediment load in the tributary increased. An obvious upstream-directed density current occurred in the backwater zone when the sediment concentration of the hyperconcentrated flow exceeded a critical value. The travel distance of the density current increased as the sediment load in the tributary increased. A formula was proposed, based on sediment continuity, for estimating the deposition volume in the reach downstream of the junction. Compared with ordinary sediment-laden flow confluences, hyperconcentrated flow confluences have a sandbar in the backwater zone associated with an upstream-directed density current that may sometimes block the main channel. Hyperconcentrated flow confluences have a thalweg, and so are different from debris flow confluences, which have a fan-shaped deposit.

  18. Fluvial dissolved inorganic C dynamics in the Western Amazonian basin: where does this carbon come from?

    NASA Astrophysics Data System (ADS)

    Waldron, S.; Vihermaa, L. E.; Newton, J.; Krusche, A.; Salimon, C.

    2012-04-01

    The Amazon river and tributaries constitute globally a significant freshwater body and thus a source of atmospheric carbon dioxide. Aquatic carbon dioxide may originate from biological or physicochemical reprocessing of allochthonous dissolved, particulate or inorganic C (ecosystem-derived C, EDC) or it may derive from groundwater inputs of dissolved inorganic C through lithological weathering by soil-derived organic acids or by the dissolution of atmospheric carbon dioxide (minerogenic-derived C, MDC). In addition to quantifying and scaling catchment source import and export terms, accurate budgeting requires additional source differentiation. The significance of MDC is not usually considered by those assessing carbon dioxide efflux, yet differentiating MDC from EDC is crucial. For example, MDC should be less directly affected than EDC by future climatic change, becoming proportionally more important to fluvial carbon dioxide efflux in drought episodes. We are measuring the stable carbon isotopic ratio of dissolved inorganic C to determine the relative importance of MDC and EDC to total C loads in the Tambopata basin in Western Peru. This is an area little studied for C cycling, but important as the soils here are more nutrient rich than the remainder of the Amazon basin which is more studied. Our field station is in the Tambopata national park and since 2010 we have sampled four different river systems which vary in size and drainage characteristics: the Tambopata, (CA ~14,000 km sq.; ~30% of its in the Andes Mountains); La Torre (~2000 km sq.), New Colpita and Main Trail (both < 2 km sq. forest drainage but Main Trail only active in the wet season). Additionally the pH, conductivity, dissolved oxygen, water temperature and stage height have been monitored in these drainage systems where possible by logging at 15 minute intervals. Our data shows that there are statistically significant differences in carbon isotopic composition (ranging from -14 to -29 ‰) and [DIC] concentration (ranging from 0.1 to 0.7 mM) between rivers, which we interpret to represent differences in the MDC / EDC input. We will present this data and discuss in more detail local, seasonal and regional controls on composition, and its application in source contribution apportionment. Whilst we are utilising this DIC isotope tracer to differentiate the source of DIC (and ultimately effluxed carbon dioxide) this study shows the potential of utilising the DIC-C isotopic composition as a tracer of groundwater-surface water interaction.

  19. Late Weichselian fluvial evolution on the southern Kara Sea Shelf, North Siberia

    NASA Astrophysics Data System (ADS)

    Dittmers, K.; Niessen, F.; Stein, R.

    2008-02-01

    Glaciations had a profound impact on the global sea-level and particularly on the Arctic environments. One of the key questions related to this topic is, how did the discharge of the Siberian Ob and Yenisei rivers interact with a proximal ice sheet? In order to answer this question high-resolution (1-12 kHz), shallow-penetration seismic profiles were collected on the passive continental margin of the Kara Sea Shelf to study the paleo-drainage pattern of the Ob and Yenisei rivers. Both rivers incised into the recent shelf, leaving filled and unfilled river channels and river canyons/valleys connecting to a complex paleo-drainage network. These channels have been subaerially formed during a regressive phase of the global sea-level during the Last Glacial Maximum. Beyond recent shelf depths of 120 m particle transport is manifested in submarine channel-levee complexes acting as conveyor for fluvial-derived fines. In the NE area, uniform draping sediments are observed. Major morphology determining factors are (1) sea-level fluctuations and (2) LGM ice sheet influence. Most individual channels show geometries typical for meandering rivers and appear to be an order of magnitude larger than recent channel profiles of gauge stations on land. The Yenisei paleo-channels have larger dimensions than the Ob examples and could be originated by additional water release during the melt of LGM Putoran ice masses. Asymmetrical submarine channel-levee complexes with channel depths of 60 m and more developed, in some places bordered by glacially dominated morphology, implying deflection by the LGM ice masses. A total of more than 12,000 km of acoustic profiles reveal no evidence for an ice-dammed lake of greater areal extent postulated by several workers. Furthermore, the existence of the channel-levee complexes is indicative of unhindered sediment flow to the north. Channels situated on the shelf above 120-m water depth exhibit no phases of ponding and or infill during sea-level lowstand. These findings denote the non-existence of an ice sheet on large areas of the Kara Sea shelf.

  20. Fluvial system development and subsequent marine transgression in Yellow River (Huanghe) delta and its adjacent sea regions during last glacial maximum to early Holocene

    NASA Astrophysics Data System (ADS)

    Zhou, Liangyong; Liu, Jian; Saito, Yoshiki; Liu, J. Paul; Li, Guangxue; Liu, Qingsong; Gao, Maosheng; Qiu, Jiandong

    2014-11-01

    Paleotopography of the Yellow River (Huanghe) delta area and the western Bohai Sea during the last glacial maximum (LGM) is important to understand fluvial activities of the Yellow River linked with the LGM climate. By integrating data sets of both onshore and offshore borehole cores and offshore high-resolution seismic profiles, we reconstructed the paleotopography of this area from the LGM to the early Holocene. The fluvial sediment facies of the LGM identified in these cores was characterized by poorly sorted medium- to coarse-grained sands, which shows chaotic patterns in seismic profiles. REE characteristics and clay mineral components of the fluvial sediments suggest that they were derived mostly from the paleo-Yellow River. The basal and top bounding surfaces of the fluvial sediments slope very gently toward the northeast, similar to the present morphology of the North China Plain formed by the Yellow River. No incised valley morphology is detected in the basal topography, because of the long distance from the study area to the paleoshoreline during the LGM, and also because of the very gentle gradient of the paleo-Yellow River from the northern part of North China Plain to the continental shelf area, with concave-upward morphology. Aggradational stacking of the fluvial sediments over the entire North China Plain and in the study area indicates that the Yellow River flowed in these areas during the LGM to the early Holocene. The Holocene marine and coastal sediments onlap onto the underlying fluvial sediments. These basal marine or brackish sediments are diachronous from offshore areas of the Bohai Sea to the Yellow River delta area, with older sediments in the east and younger sediments in the west, which clearly reflects the early Holocene marine transgression from the North Yellow Sea to the Bohai Sea.

  1. Volcanic and climatic controls on fluvial style in a high-energy system: The Lower Cretaceous Matasiete Formation, Golfo San Jorge basin, Argentina

    NASA Astrophysics Data System (ADS)

    Paredes, José Matildo; Foix, Nicolás; Colombo Piñol, Ferrán; Nillni, Adriana; Allard, José O.; Marquillas, Rosa A.

    2007-11-01

    The Cretaceous Chubut Group in the Golfo San Jorge Basin (Patagonia, Argentina) comprises up to 6000 m of continental sediments. At the base of the succession, an extensive saline-alkaline lacustrine unit (Pozo D-129 Fm) grades laterally towards the basin margin into the fluvial Matasiete Fm (Hauterivian?-Aptian). The Matasiete Fm comprises up to 650 m of siliciclastic and pyroclastic deposits in its type area, where three Members have been distinguished. The following facies associations were identified: 1) single fluvial channels; 2) multistorey fluvial channels; 3) proximal floodplain; 4) distal floodplain; 5) pyroclastic (ash-fall and ground-surge) deposits. Additional observations in the time-equivalent Pozo D-129 Fm provide evidence for 6) shallow lacustrine, and 7) deep-lacustrine facies associations. The floodplain association contains paleosols with abundant carbonate concretions and fine pyroclastic tuffs. Paleosols are mostly vertisols, characterized by deep desiccation cracks, slickensides and carbonate nodules. These observations, coupled with the occurrence of shallow-water oolitic grainstones in the lacustrine Pozo D-129 Fm indicate a semiarid environment. Tree trunks up to 1 m in diameter and 15 m long, preferentially located near channel margins, provide evidence for vegetated riverbanks. The exposures of the Matasiete formation in the San Bernardo Fold Belt show individual channel belts containing straight, meandering and braided channels. Evidence of changes in fluvial style attributable to base-level control has not been observed. The most dramatic changes in fluvial architecture, which were comparatively short-lived, were provoked by intermittent pyroclastic deposition on the floodplain. The reduced infiltration capacity of the floodplain and the concomitant increase in sediment load increased runoff, as well as volume and flashiness of the discharge, which favoured the development of shallow, multichannel rivers. The fluvial system abruptly changed from single, ribbon channels to a braided system, which notably increased the width/thickness ratio of sandbodies.

  2. Geological and Petrophysical Characterization of the Ferron Sandstone for 3-D Simulation of a Fluvial-Deltaic Reservoir

    SciTech Connect

    M. Lee Allison

    1997-03-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reser v oir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similiar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined . Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations . Transfer of the project results to the petroleum industry is an integral component of the project. Four activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone in the Ivie Creek case-study area: (1) geostatistics, (2) field description of clinoform bounding surfaces, (3) reservoir modeling, and (4) technology transfer.

  3. Distribution of Lower Cambrian fluvial and progradational marine facies along frontal Blue Ridge: Chilhowee Group of east Tennessee

    SciTech Connect

    Walker, D.; Driese, S.G.

    1989-03-01

    The Chilhowee Group (upper Proterozoic-Lower Cambrian) of eastern Tennessee represents a fluvial-to-marine transition that accompanied the stabilization on the eastern North American continental margin formed by the inception of the Iapetos Ocean. Variability along strike in Chilhowee facies has been recognized within the confines of the fluvial-to-marine transition. Facies, identified across eastern Tennessee study localities, cross formational boundaries; thus, a facies analysis provides a practical basis for studying patterns of Chilhowee sedimentation. Throughout eastern Tennessee, five facies were recognized: conglomerate, sandstone, siltstone-mudstone, hummocky, and quartz-arenite. Variations in the relative abundance and stratigraphic position of shelf facies (hummocky and mudstone-siltstone facies), grain size, and bed thickness within the Chilhowee Group represent variations in coeval Chilhowee paleoenvironments along strike, attributable to differences in progradation vs. transgression at the continental margin. Examination of the Chilhowee Group within two major segments of the Great Smoky thrust complex indicates that the current relative distribution of facies differs from that inferred for the original depositional system. This difference may reflect (1) variation in the amount of tectonic transport experienced by the various segments of the thrust complex, (2) divergence between structural strike and depositional strike, or (3) the effect of local promontories and embayments within the North American-Iapetos continental margin.

  4. Variations in fluvial style in Westwater Canyon member, Morrison Formation (Jurassic), southern San Juan basin, Colorado plateau

    SciTech Connect

    Miall, A.D.; Turner-Peterson, C.E.

    1988-02-01

    The large-scale architecture of fluvial strata within the Westwater Canyon Member of the Morrison Formation consists mainly of a series of tabular sheets of sandstone 5-15 m thick and hundreds of meters wide separated by thin fine-grained units. These sandstone sheets are commonly flat bedded; however, lateral accretion surfaces and channels 10-20 m deep and up to at least 250 m wide are also present. Where studied in detail, the sheets comprise a complex of elements and bounding surfaces unlike any previously described from ancient fluvial deposits. Lateral accretion deposits, typical indicators of moderate to high-sinuosity channels, coexist in the same outcrop with downstream-accreted foreset macroform deposits now thought to be typical of the sand flats of low-sinuosity, multiple-channel rivers. Broad deep channels with gently to steeply dipping margins have been mapped by carefully tracing major bounding surfaces in several of the outcrops. Fining-upward sequences are rare in the project area, contrary to earlier descriptions. Analogies with the depositional architecture of the large Indian rivers, such as the Ganga and Brahmaputra, still seem reasonable, although convincing evidence now exists for aridity and for major stage fluctuations, which differs from those modern rivers and previous interpretations.

  5. Use of an intact core and stable-metal isotopes to examine leaching characteristics of a fluvial tailings deposit

    USGS Publications Warehouse

    Ranville, James F.; Smith, Kathleen S.; Lamothe, Paul J.; Jackson, Brian P.; Walton-Day, Katie

    2003-01-01

    In this paper, we use Cd as an example of the utility of stable-metal isotopes in geochemical studies. In the case of Cd, after the core was partially saturated, the 111Cd spike was released as evidenced by a change in the Cd isotope ratios in the effluent. This release continued during the fully saturated leaching phase, however, the total Cd concentration did not increase. These results suggest that the 111Cd spike was retained inside the core during the unsaturated leaching phase, and only partially released as reducing conditions developed. Results from this core-leaching experiment indicate there is a large reservoir of water-soluble material within the fluvial tailings deposit, which yields elevated metal concentrations and high acidity, and which may degrade adjacent ground- and surface-water quality. Use of stable metal isotopes in this study facilitated the determination of different metal-retention processes, metal-release processes, and metal sources in the fluvial tailings deposit in response to changing geochemical conditions.

  6. Combining impact sensor field and laboratory flume measurements with other techniques for studying fluvial bedload transport in steep mountain streams

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.; Laute, Katja

    2014-08-01

    The timing and rate of fluvial bedload transport are of central importance within sediment budget studies and in many applications in river science and engineering. During the years 2010, 2011 and 2012 detailed field measurements with portable impact sensors as a non-invasive technique for indirectly determining fluvial bedload transport intensity were conducted in two instrumented and supply-limited drainage basin systems (Erdalen and Bødalen) in the fjord landscape in western Norway. Additional field measurements with portable impact sensors were carried out in 2010 and 2011 in selected transport-limited fluvial systems in the Coast Mountains of western Canada. The collected impact sensor field data were calibrated with laboratory flume experiments. The data from the impact sensor field measurements in western Norway and the flume experiments were combined with field data from continuous discharge monitoring, repeated surveys of channel morphometry and sediment texture, particle tracer measurements, Helley-Smith samplings, underwater video filming and biofilm analyses. The combination of methods and techniques applied provides insights into the temporal variability and intensity of fluvial bedload transport in the selected mountain streams: (i) in the transport-limited systems with generally high bedload transport rates during high discharge and with bedload material moving in clusters over the impact sensor plates, impact sensor data (based on a 1 s measuring interval) provide the opportunity to detect the start and end of bedload transport, thus to identify discharge thresholds for sediment entrainment, and to roughly estimate the intensity and relative intensity of change of bedload transport during the measuring period; (ii) in the supply-limited systems with low bedload transport rates and bedload components moving separately (as single particles) over the impact sensor plates, impact sensor data (with a 1 s measuring interval) allow the detection of the start and end of transport of bedload components > 11.3 mm, thus the identification of discharge thresholds for possible entrainment of particles, the quantification of the number of particles > 11.3 mm moving over the impact sensor plates during the measuring period, the rough estimation of grain sizes of the particles moving separately over the impact sensor plates, and the calculation of the total mass of the bedload material > 11.3 mm moving over the impact sensor plates during the measuring period; (iii) when combined with other methods and techniques (Helley-Smith sampling, particle tracer measurements, biofilm analyses, underwater video filming) which provide information on the active bedload transport channel width, on discharge thresholds for possible entrainment of particles of different grain sizes, and on transport rates of bedload material < 11.3 mm, total rates of fluvial bedload transport, covering all given grain sizes of the bedload material, can be calculated for the supply-limited mountain streams with generally low bedload transport. The higher measured annual bedload yield in Bødalen (13.6 t km- 2 yr- 1) compared to Erdalen (2.6 t km- 2 yr- 1) reflects a higher level of slope-channel coupling in Bødalen than in Erdalen.

  7. Does Model Development Ahead of Data Collection Have Merit? A Case for Advancing Non-Local Fluvial Transport Theories

    NASA Astrophysics Data System (ADS)

    Voller, V. R.; Falcini, F.; Foufoula-Georgiou, E.; Ganti, V.; Paola, C.; Hill, K. M.; Swenson, J. B.; Longjas, A.

    2013-12-01

    The purpose of this work is to suggest how experiments might be constructed to provide data to test recently proposed phenomenological non-local model of depositional transport; formulated on the basis of morphological arguments but with limited data. A sound methodology for developing models of geological systems is to first collect significant data and then carefully identify an appropriate model form and parameters. An alternative approach is to construct what might be referred to as a phenomenological model, where limited observation of the system is used to suggest an appropriate mathematical form that matches the critical nature of the physical system behavior. By their nature, phenomenological models are often developed within a fairly narrow range of observations. In this way, interesting findings can occur when the models are modified and exercised across wider physical domains, in particular in domains where there is an absence of hard data to corroborate or invalidate the model predictions. Although this approach might be frown on my some, it is important to recognize the stellar and proven track record of phenomenological models, which despite the original scarcity of data, often pave the way to new perspectives and important findings. The poster child example is the Higgs boson. In the early 60's manipulation of the quantum field equations revealed a critical inconsistency related to the masses of fundamental particles that could only be mathematically resolved by assuming that they operated within a field that would exert drag; this conjecture took almost fifty years and the vast experimental operation of the Large Hadron Collider to physically confirm. In this work we examine a current phenomenological model used to describe non-local transport in fluvial sediment domains. This model has its genesis in attempting to describe the shapes of hill slope profiles, while acknowledging the fact that two points of the landscape with the same local slope are not always associated with the same sediment flux. The key innovation then is to model the sediment flux at a point in terms of an upstream weighted sum of fluvial slopes or other geomorphological attributes of the system. In the hill-slope context, the downstream flow of information in this non-local formalism is well supported by fundamental observations of the distribution of downstream particle transport distances. However, when the same model is applied in the context of depositional systems it appears to be inconsistent with profiles of depositional surfaces. In particular, the model predicts fluvial profiles with curvature signs opposite to those observed in nature. When a simple mathematical manipulation is made, where the flux at a point is expressed as a downstream weighting of fluvial slopes, however, predictions with the correct form are recovered. At this time, no specific mechanism or clear corroborating data have been identified that would explain this downstream control. Does this mean we should ignore this result or would it be better to use it as a motivation to seek out hypotheses tests that would confirm or invalidate the current suggested models of downstream non-local transport? A series of innovative experiments that address the collection of experimental evidence for downstream control in fluvial transport are described.

  8. Upstream facing convex surfaces and the importance of bedload in fluvial bedrock incision: observations from Taiwan.

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew; Hovius, Niels

    2010-05-01

    Until recently many bedrock bedforms have been little more than ornate curiosities found in many bedrock river channels because few process-form linkages had been established for the myriad of forms recognised in the literature. In addition rates of bedrock bedform development from direct observations in natural channels are rare due to difficulties in confidently linking spatial observations from two monitoring visits using extant methods. We have documented bedrock bedforms present at 45 river locations in a survey of Taiwanese rivers and monitored erosion at sites on a single river, the Li Wu River, between 2007 and 2008. Taiwan is an ideal location to investigate bedrock bedforms produced by bedload abrasion due to regular high discharge events, high discharge variability, high sediment transport rates of bedload calibre material, and documented high fluvial bedrock erosion rates. In this paper we present surface texture observations (photographs and scanning electron microscope images) of a particularly common variety of bedrock bedform found in Taiwanese rivers: upstream facing convex surfaces (UFCS). A distinct contrast exists in surface textures, on two scales of observation, between the upstream and downstream facing facets. On a millimetre scale, upstream facing convex surfaces have a sugary roughness with centimetre-scale pits superimposed on a larger-scale smoothed convex form. In contrast downstream facing surfaces are often more intricately sculpted on a centimetre scale with millimetre- to micrometre-scale roughness, defined by roughness elements smaller than the rock forming grain, superimposed on an often undulatory concave form. A linear crestline feature marks the change in slope and surface texture of the bedform and is orientated approximately normal to the channel axis. To complement these qualitative observations we present a novel method to quantify small-magnitude surface changes by using embedded, two-part datums and conventional 3D laser scanning. Using this method the kinematics of ten nascent upstream facing convex surfaces were determined by differencing three-dimensional models acquired in March of 2007 and 2008. A feature common to all sites is an asymmetric pattern of erosion at the scale of the bedform. Erosion was dominantly focused on the upstream facing surfaces whereas the downstream facing surfaces experienced minor erosion. The linear crestline maps the boundary between high and low relative erosion rates, in addition to marking the boundary between changing surface texture and slope characteristics. To a much lesser extent, in some cases, erosion is also spatially variable within each facet of the bedrock bedform. We argue that the erosion of the upstream facing, or stoss, surface of this variety of bedrock bedform is the work of abrasion by bedload, which by being decoupled from the flow can only impact the stoss surface to any significant extent. If this is the case then the high erosion rates observed indicate that abrasion by bedload is the controlling process in the formation of this variety of bedrock bedform and perhaps the channel at large in this setting. Lee surfaces, which are sculpted more slowly, are the product of suspended load abrasion due to much smaller particles impacting the substrate in the lee of the obstacle where they are ejected from tightly curved flow lines. As bedload accounts for only ~30% of the total river sediment load yet bedload abrasion accounts for virtually all the erosion on UFCSs, the quantity of bedload passing through bedrock rivers has a strong control on channel incision rates.

  9. Rapid fluvial aggradation in response to climate change in northwestern Argentina

    NASA Astrophysics Data System (ADS)

    Wickert, Andrew; Schildgen, Taylor; Strecker, Manfred

    2015-04-01

    River channels near the edge of the northwestern Argentine Andes are rapidly aggrading at present, with preliminary estimates suggesting rates of ~20 cm yr-1. This mirrors cycles of extensive aggradation over the past 100,000 years that formed pronounced fill terraces along regional valley networks and record periods in which in which climate-driven sediment supply overcame uplift-driven river incision (Robinson et al, 2005). Here we use the new SedFlow model (Heimann et al., 2014) to help us understand the causes and spread of aggradation across these basins in the modern system, with the additional eventual goal to better interpret the geologic record. We provide field-derived grain-size distributions, field-measured and remotely-sensed channel widths and valley slopes, and a variety of possible sediment source locations and amounts as inputs to SedFlow, which routes sediment through the fluvial channel network to produce time-evolving predictions of aggradation and incision. We compare these predictions against changes in topography measured by IceSAT (Zwally et al., 2014) and field surveys. We initially test the system response to a series of isolated sediment inputs to observe interactions between tributary systems and the mainstem river. Recent observations indicate that debris-flow induced landslides are important contributors to aggradation in these rivers (Cencetti and Rivelli, 2011). These and other sediment production and transport processes are likely driven by variations in the El Niño Southern Oscillation (ENSO) (Bookhagen and Strecker, 2009). Therefore, we then run SedFlow with sediment inputs distributed across the landscape based on locations where ENSO influences may trigger enhanced landsliding. These model experiments help us towards our end goal of providing a more quantitative basis to interpret field observations of landscape response to changing patterns of precipitation. References: Bookhagen, B. and Strecker, M.: Amazonia: Landscape and Species Evolution, in Amazonia, Landscape and Species Evolution: A Look into the Past, edited by C. Hoorn and F. P. Wesselingh, Wiley-Blackwell Publishing Ltd., Oxford, UK., 2009. Cencetti, C. and Rivelli, F. R.: Landslides Dams Induced by Debris Flows in Quebrada Del Toro (Province of Salta, Argentina), in 5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment, pp. 645-650, Casa Editrice Università La Sapienza, Padua, Italy., 2011. Heimann, F. U. M., Rickenmann, D., Turowski, J. M. and Kirchner, J. W.: sedFlow - an efficient tool for simulating bedload transport, bed roughness, and longitudinal profile evolution in mountain streams, Earth Surf. Dyn. Discuss., 2(2), 733-772, doi:10.5194/esurfd-2-733-2014, 2014. Robinson, R. a. J., Spencer, J. Q. G., Strecker, M. R., Richter, a. and Alonso, R. N.: Luminescence dating of alluvial fans in intramontane basins of NW Argentina, Geol. Soc. London, Spec. Publ., 251(1), 153-168, doi:10.1144/GSL.SP.2005.251.01.11, 2005. Zwally, H., R. Schutz, C. Bentley, J. Bufton, T. Herring, J. Minster, J. Spinhirne, and R. Thomas. GLAS/ICESat L1B Global Elevation Data. Version 34. GLA06. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. http://dx.doi.org/10.5067/ICESAT/GLAS/DATA126. 2014.

  10. Agua Caliente Solar Feasibility and Pre-Development Study Final Report

    SciTech Connect

    Carolyn T. Stewart, Managing Partner; Red Mountain Energy Partners

    2011-04-26

    Evaluation of facility- and commercial-scale solar energy projects on the Agua Caliente Band of Cahuilla Indians Reservation in Palm Springs, CA. The Agua Caliente Band of Cahuilla Indians (ACBCI) conducted a feasibility and pre-development study of potential solar projects on its lands in southern California. As described below, this study as a logical and necessary next step for ACBCI. Support for solar project development in California, provided through the statewide California Solar Initiative (CSI), its Renewable Portfolio Standard and Feed-in Tariff Program, and recently announced Reverse Auction Mechanism, provide unprecedented support and incentives that can be utilized by customers of California's investor-owned utilities. Department of Energy (DOE) Tribal Energy Program funding allowed ACBCI to complete its next logical step to implement its Strategic Energy Plan, consistent with its energy and sustainability goals.

  11. An Early Pennsylvanian threshold for the influence of vegetation on fluvial landscapes, based on the geological record of Atlantic Canada

    NASA Astrophysics Data System (ADS)

    Gibling, Martin; Ielpi, Alessandro; Bashforth, Arden; Davies, Neil

    2015-04-01

    Vegetation profoundly influences modern fluvial systems, depending on plant life-history strategies, tolerance to disturbance, and habitat drainage. However, direct evidence for these dynamic relationships is cryptic and has commonly been overlooked in ancient deposits. We report evidence for profound interactions between channels, in situ and transported vegetation in Lower Pennsylvanian formations of Atlantic Canada (~310 Ma), attributed to braided, meandering and fixed-channel (anastomosing) systems. Plant groups include lycopsids that preferred stable wetland settings, disturbance-tolerant calamitaleans, and deeply rooted cordaitaleans (early gymnosperms) that originated in the late Mississippian and colonised both wetland and dryland settings. For the meandering and anastomosing channel deposits, upright vegetation was observed within channel-based bedforms and bars and on channel margins. Lycopsids and calamitalean groves colonized the channel bed and bank-attached bars during periods of reduced flow, nucleating bar growth after flow resumed. Upright lycopsids and cordaitaleans are common along channel cutbanks and are locally tilted towards the channel, implying involvement in bank stabilization. Rhizoconcretions that formed around deep cordaitalean roots may have aided bank reinforcement. Tetrapod and arthropod trackways in the channel deposits indicate a close linkage between riparian and aquatic ecosystems. In the braided systems, sediments that contain abundant cordaitalean logs constitute nearly 20% of channel deposits, and the logs form channel-base lags, fill channels up to 6 m deep, and form nuclei for shallow sandbars. Log accumulations overlain by shale lenses imply a contribution to channel avulsion. Rooted channel-sandstones containing upright trees are interpreted as vegetated islands in an island-braided system. Anastomosing systems are abundant in these Lower Pennsylvanian formations but rare in older strata, and the multi-channel island-braided systems are the oldest yet described. The rise to prominence of these two anabranching styles, broadly coinciding with the rise of cordaitaleans, implies that fluvial landscapes had crossed a threshold from a geomorphic and biogeomorphic mode of operation into a fully ecological mode with feedback loops between vegetation and fluvial processes. Thereafter, patterns of interaction between rivers and vegetation broadly resembled those of today, with prominent riparian corridors and profound consequences for aquatic, soil and other terrestrial ecosystems. Our field observations confirm the co-evolution of river systems, vegetation and animals, and highlight a need to incorporate vegetation more fully into earth-system and landscape models.

  12. Investigating microbial diversity and UV radiation impact at the high-altitude Lake Aguas Calientes, Chile

    Microsoft Academic Search

    Lorena Escudero; Guillermo Chong; Cecilia Demergasso; María Eugenia Farías; Nathalie A. Cabrol; Edmond Grin; Edwin Minkley Jr.; Yeoungeob Yu

    2007-01-01

    The High-Lakes Project is funded by the NAI and explores the highest perennial volcanic lakes on Earth in the Bolivian and Chilean Andes, including several lakes ~6,000 m elevation. These lakes represent an opportunity to study the evolution of microbial organisms in relatively shallow waters not providing substantial protection against UV radiation. Aguas Calientes (5,870 m) was investigated (November 2006)

  13. El sistema kárstico en yesos de la cueva del agua (Sorbas, Almería)

    Microsoft Academic Search

    José María Calaforra; Francisco Sánchez-Martos

    The Agua Cave karst system, wich is about 6.7 km long, is the most important gypsum cave in Spain. It is in relation with a dol ine of about 1.5 km 2 with one hundred sink-holes of access inside. The system is controled by fractures N150º-160ºE and N40º-50ºE. We have recognize a diferential geomorphological evolution in accordance with the presence

  14. Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir (Pre-Work and Project Proposal), Class I

    SciTech Connect

    Bou-Mikael, Sami

    2002-02-05

    This project outlines a proposal to improve the recovery of light oil from waterflooded fluvial dominated deltaic (FDD) reservoir through a miscible carbon dioxide (CO2) flood. The site is the Port Neches Field in Orange County, Texas. The field is well explored and well exploited. The project area is 270 acres within the Port Neches Field.

  15. Chapter 19 Evolution of Quaternary to Modern Fluvial Network in the Mid-Hungarian Plain, Indicated by Heavy Mineral Distributions and Statistical Analysis of Heavy Mineral Data

    Microsoft Academic Search

    Lajos Ó. Kovács

    2007-01-01

    Heavy mineral data of 590 samples from ten cored boreholes, penetrated into Quaternary fluvial successions in the central part of the Hungarian Plain, and complemented by data from modern river sediments, have been evaluated using numerical methods. Cluster analysis and principal component analysis (PCA) have revealed appreciable similarities between the heavy mineral composition of modern river sediments and those from

  16. Amazonian-aged fluvial valley systems in a climatic microenvironment on Mars: Melting of ice deposits on the interior of Lyot Crater

    Microsoft Academic Search

    J. L. Dickson; C. I. Fassett; J. W. Head

    2009-01-01

    Valley networks, regional drainage patterns suggesting liquid water stability at the surface, are confined to early in the history of Mars (the Noachian\\/Hesperian boundary and before), prior to a major climate transition to the hyperarid cold conditions of the Amazonian. Several later fluvial valley systems have been documented in specific Hesperian and Early Amazonian environments, and are thought to have

  17. The Association of Anastomosed fluvial deposits and dinosaur tracks, eggs, and nests: Implications for the interpretation of floodplain environments and a possible survival strategy for ornithopods

    SciTech Connect

    Nadon, G.C. (Univ. of Wisconsin, Madison (United States))

    1993-02-01

    The St. Mary River Formation (Maastrichtian) consists of anastomosed fluvial deposits containing several hundred track-bearing beds. Paleontologic and sedimentologic analyses of these beds indicate that large herbivores, ornithopods, inhabited a seasonal wetland dominated by marshes and lakes. Shallow tracks in fine-grained sediments, formed as the sediments dewatered to the point of stiffness, display the highest resolution of detail. The preservation potential of tracks in anastomosed fluvial deposits is large because of the abundance of soft substrates to record the tracks and the occurrence of annual flooding to rapidly bury the footprints. Comparison of the St. Mary River Formation to other anastomosed fluvial deposits as old as the Early Jurassic confirms that tracks are common in this type of deposit. The variation in preservation of track types and depth of penetration raises the possibility that ornithopods employed a survival strategy involving seasonal wetlands. The wetlands provided an abundant food source and at the same time the combination of a soft substrate and flooded conditions would have effectively countered the superior speed and agility of large carnivores. The relatively common occurrence of ornithopod eggshells from anastomosed fluvial deposits suggests that the abundant food supply accompanying the wet season also made the wetlands an ideal location to rear young. These data can be used to refine the interpretations of depositional environment derived from the sediments by allowing estimates to be made regarding the early post-depositional conditions of the sediments. 95 refs., 7 figs., 1 tab.

  18. Deposition and diagenesis of the lacustrine-fluvial Cangfanggou Group (uppermost Permian to Lower Triassic), southern Junggar Basin, NW China: a contribution from sequence stratigraphy

    Microsoft Academic Search

    Zhaohui Tang; John Parnell; Alastair H. Ruffell

    1994-01-01

    The Junggar Basin in NW China contains lacustrine hydrocarbon source rocks which are among the highest quality of hydrocarbon potential in the world. Oil reservoirs in the basin are very substantial: target reservoirs span Carboniferous to Tertiary strata and include Permo-Triassic lacustrine and fluvial sandstones. The Junggar Basin was a foreland basin during the late Permian to Cenozoic, possibly with

  19. Combined 40Ar\\/39Ar and OSL dating of Pleistocene pyroclastic and fluvial deposits of the Cagayan Valley Basin, Northern Luzon, Philippines

    Microsoft Academic Search

    Gitte M. Jensen; Michael Storey; Richard Roberts; Terry J. Lachlan; Kristina J. Thomsen; Andrew Murray

    2010-01-01

    The backarc Cagayan Valley Basin (250 x 80 km) of Northern Luzon, Philippines has a 10 km thick sedimentary infill deposited since the late Oligocene. The upper 900 m consists of non-marine Plio-Pleistocene fluvial sediments with interbedded pyroclastic deposits. Fossil vertebrates and stone artefacts occur within the upper part of this succession. The terrestrial vertebrate fauna is thought to have

  20. Fluvial geochemistry of the eastern slope of the northeastern Andes and its foredeep in the drainage of the Orinoco in Colombia and Venezuela

    Microsoft Academic Search

    J. M. Edmond; M. R. Palmer; C. I. Measures; E. T. Brown; Y. Huh

    1996-01-01

    The fluvial geochemistry of the tributaries of the Orinoco draining the eastern branch of the northern Andes in Colombia and Venezuela is determined by lithology and ranges from rivers dominated by aluminosilicate weathering, mainly of shales and mafic rocks, to those bearing the signatures of dissolution of marine limestones and evaporites and of continental playa deposits. These left bank tributaries

  1. The distribution of the Rocky Mountain tailed frog ( Ascaphus montanus ) in relation to the fluvial system: implications for management and conservation

    Microsoft Academic Search

    Linda Dupuis; Pierre Friele

    2006-01-01

    The mating, egg-laying, and larval development of tailed frogs occur in dynamic mountain streams. During the lengthy (up to 5 years) aquatic residency these species are vulnerable to channel disturbances that can be exacerbated by land uses. Researchers have highlighted specific tailed frog habitat associations but never in the context of fluvial system processes. Based on an extensive regional study with

  2. Bimodal palaeocurrents in braided-type inland fluvial environments in the buntsandstein of middle europe and other continental formations

    NASA Astrophysics Data System (ADS)

    Mader, Detlef

    Bimodal directional distributions can form on various scales and by numerous mechanisms in fluvial environments including braided river systems. The examination of case studies from the Lower Triassic Buntsandstein of Middle Europe and comparative assessment of other fluvial successions reveal five scales of bimodalities which are ordered in a hierarchical manner: very small-scale, small-scale, medium-scale, large-scale and very large-scale bimodalities. The different hierarchical orders of bimodalities are interrelated in four ways depending on length of the sequence, occurrence or absence of subordinate bimodalities and type of organization of the divergent palaeocurrent directions. Very small-scale bimodalities comprise differences between subsets within sets and between sets within cosets (herring-bone cross-stratification) and originate by cross or reverse flow during isolated phases within stages of infilling of individual channels. Small-scale bimodalities comprise differences between sets within cosets and originate by cross or reverse flow during repeated phases within stages of infilling of individual channels. Medium-scale bimodalities comprise differences between cosets within cyclothems and between cyclothems within megacycles and originate by cross or reverse flow between stages of infilling of several channels and various orientations of the streams, combined with effects of condensation of the depositional record. Large-scale bimodalities comprise differences between cyclothems within megacycles and originate by changes of current direction between stages of aggradation of parts of the alluvial plain. Very large-scale bimodalities comprise differences between megacycles within the magnacycle and originate by changes of current direction during stages of aggradation of the alluvial plain or by superimposition of successive separate alluvial plains. The effect of medium-scale bimodalities in the depositional record is strongly enhanced by condensation of the sequence by two mechanisms: primary-sedimentary restriction to suppression of formation and secondary-erosional degradation to removal of floodplain deposits and finer-grained watercourse sands. As a consequence of vertical stacking of successive channel sediments to multistorey complexes and amalgamation of adjoining stream deposits to multilateral sheets by horizontal coalescence, different orientations of successive channels are emphasized by juxtaposition due to cut out of products of intervening subenvironments. The most prominent example of large-scale bimodalities is a time-cyclic trend of sedimentation with spatially continuous and time-concordant shifting of the dominantly braided river channels in a transitional meandering thalweg — braided stream pattern, resulting in changes of transport directions with time in a sinusoidal manner. The sinuous reaches between both negative and positive extremes of deviation values and the meandering deviation curves can be correlated. The subdivision of the Buntsandstein sequence into units with comparable palaeocurrent deviations gives evidence of the applicability of the palaeoflow interpretation in the stratigraphical analysis of continental formations. In contrast to the smaller-scale bimodalities which are exclusively controlled by autocyclic processes of aggradation of the alluvial plain, the formation of very large-scale bimodalities is often governed by allocyclic influences from tectonical events. The palaeoenvironmental interpretation and depositional modelling of fluvial successions can be greatly enhanced by an integrated approach including both examination of energy-sensitive sedimentary structures and analysis of the bidirectional distribution of the palaeocurrents. The numerous possibilities of changes and variations of palaeocurrent directions in time and space on several scales underline the architectural complexity of fluvial systems due to extrabasinal and internal controls on the orientation of flows.

  3. Large fluvial systems: the Atane Formation, a fluvio-deltaic example from the Upper Cretaceous of central West Greenland

    NASA Astrophysics Data System (ADS)

    Olsen, Torben

    1993-05-01

    Recognition of major river deposits are crucial to the understanding of palaeogeography and basin evolution. This paper describes the geometry of 2-30 m thick fluvial sand-bodies which occur in Upper Cretaceous strata deposited in a major river delta in central West Greenland. The deposits are cyclic and each cycle can be divided into four genetic facies associations which reflect deposition: (1) at the delta-front, (2) on the delta-plain, (3) in fluvial channels, and (4) during transgression of a delta lobe. The cyclicity is attributed mainly to autocyclic shifting of delta lobes. The study area is very well exposed and an advanced, new photogrammetric system was used both for making accurate vertical profiles and for mapping the horizontal extent of individual sand-bodies. Based on horizontal extent, internal architecture and relationship to other facies associations, the c. 100 investigated sand-bodies from the fluvial channel association can be divided into two important types. Distributary channel sand-bodies are the dominant type (80%). They vary in thickness from 3 m up to as much as 30 m and reflect the migration and infilling of rather narrow distributary channels that existed on a flat, vegetated delta-plain. The relationship with the surrounding sediments as well as faint epsilon cross-beds which extend right through the sand-bodies indicate that the thicknesses of the sand-bodies approximate the bankfull depth of the palaeochannels. Many small and medium-sized sand-bodies have very narrow cross-sections and show no signs of lateral migration. The preserved geometry of these sand-bodies consequently represents the original channel morphology. The sand-bodies show an increasing degree of migration with increasing thickness and the width/thickness ratio increases from c. 6 for the smaller sand-bodies up to c. 20 for the largest. The distributary channels were only moderately sinuous with an average sinuosity of 1.2. Channel mouth complexes are the other type of fluvial sand-bodies (20%). They are 3-8 m thick and have a large lateral extent with a width/thickness ratio of 50 or more. They have an erosive base and occur in the top of the coarsening-upward sequences made by the delta-front association. Internal bounding surfaces suggest that these sand-bodies were generated by lateral amalgamation of many small channel fills in fan-shaped sub-deltas at the sea-ward end of distributary channels. The discharge through the distributary channels has been calculated using the Manning equation. These calculations indicate that the river system which supplied the Atane Delta was very large, and may well have drained most of the presently ice-covered interior of Greenland.

  4. Geomorphological implications of systematic age overestimations in the OSL dating of post-LGM fluvial terraces (Rangitikei river, New Zealand)

    NASA Astrophysics Data System (ADS)

    Rieser, U.; Bonnet, S.; Moulin, L.; Lacoste, A.; Lague, D.; Davy, P.

    2009-12-01

    Along the Rangitikei river flows (North Island, New Zealand), a widespread climatically-controlled fluvial terrace formed from ~30 ka to the Last Glacial Maximum. At that time, the river had a braided course and was aggrading. Since the LGM, the river has cut into the bedrock and the LGM terrace is presently preserved 75 m above the current level of the river. The post-LGM entrenchment is characterized by the formation of bedrock gorges with near-vertical valley walls, while the river was meandering. There, some minor, autocyclic fluvial terraces have been abandoned during downcutting and the flight of up to 22 post-LGM terraces is observed locally. The mapping and elevation survey of 376 LGM and post-LGM terraces highlight a bimodal elevation distribution of post-LGM terraces and the lack of post-LGM terraces within the elevation range between 20 and 50 m above the current level of the river. Optically Simulated Luminescence dating has been used to estimate the deposition age of 20 post-LGM strath terrace deposits (feldspars/polymineral silt samples with the aim to constrain in details the post-LGM incision of the river. We used Multiple Aliquot Additive Dose technique with late-light subtraction or Single Aliquot Regenerative (SAR) protocol. 19 samples give an age older than the LGM, which is the maximum age possible for these terraces. It implies a systematic overestimation of the ages. Overestimation is confirmed by the OSL dating of present-day river sediments and of sediments deposited during a major flood that occurred in 2004, whose measured ages are of 37.4 +/- 3.1 and 55.1 +/- 3.5 ka respectively. The elevation distribution of all the ages shows that overestimation is not randomly distributed: from the elevation of the LGM terrace (+75 m) to the current level of the river, all the ages align along a curve with a boomerang shape ( > ). The elevation of the older measured ages (104.4 +/- 7.7 and 106.5 +/- 7.6 ka; elevations of +30 and +20 m respectively) coincides with the elevation range where elevation distribution analysis reveals a lack of post-LGM terraces. Our analysis suggests that OSL age overestimate depends on the proportion of mixing between some grains that have been bleached during their fluvial transportation and some unbleached ones. Empirical data show that the bleaching of grains during fluvial transportation depends on the turbidity of the water. The non-random trend in OSL age overestimation most likely results from past variations in the turbidity of the river. The similarity between the OSL age trend and the post-LGM terraces elevation distribution suggests a genetic link. Our study consequently suggests that error on OSL ages could potentially be used to constrain the past dynamics of rivers.

  5. The use of fluvial and marine sediments in the formulation of roller compacted concrete for use in pavements.

    PubMed

    Zdiri, M; Abriakb, N E; Ben Ouezdoua, M; Neji, J

    2009-07-01

    In the manufacture of Roller Compacted Concrete (RCC) used for pavement materials, various types of aggregates are used, such as crushed and rolled limestone or siliceous aggregates. The main objective is always to reach the maximum compactness to achieve higher mechanical performances. In the present work, fluvial and marine sediments, resulting from the dredging of harbours and rivers, were introduced as aggregates in the preparation of RCC for pavement construction, with a view to improving the mechanical strength of the RCC. This study included a granulometric, mineralogical and chemical characterization of the aggregates. The work also contains a mechanical characterization of the resulting material. The objective of the study was to find a resistant RCC, by developing materials such as sediments that are often classified as a waste and where their storage is harmful to the environment. The mechanical strengths obtained showed the profitability of using a Roller Compacted Concrete containing sediments. PMID:19705664

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

    PubMed Central

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

    2012-01-01

    From 1997 to 2004, we used radio telemetry to investigate movement and distribution patterns of 206 adult fluvial bull trout (mean, 449 mm FL) from watersheds representing a wide range of habitat conditions in northeastern Oregon and southwestern Washington, a region for which there was little previous information about this species. Migrations between spawning and wintering locations were longest for fish from the Imnaha River (median, 89 km) and three Grande Ronde River tributaries, the Wenaha (56 km) and Lostine (41 km) rivers and Lookingglass Creek (47 km). Shorter migrations were observed in the John Day (8 km), Walla Walla (20 km) and Umatilla river (22 km) systems, where relatively extensive human alterations of the riverscape have been reported. From November through May, fish displayed station-keeping behavior within a narrow range (basin medians, 0.5–6.2 km). Prespawning migrations began after snowmelt-driven peak discharge and coincided with declining flows. Most postspawning migrations began by late September. Migration rates of individuals ranged from 0.1 to 10.7 km/day. Adults migrated to spawning grounds in consecutive years and displayed strong fidelity to previous spawning areas and winter locations. In the Grande Ronde River basin, most fish displayed an unusual fluvial pattern: After exiting the spawning tributary and entering a main stem river, individuals moved upstream to wintering habitat, often a substantial distance (maximum, 49 km). Our work provides additional evidence of a strong migratory capacity in fluvial bull trout, but the short migrations we observed suggest adult fluvial migration may be restricted in basins with substantial anthropogenic habitat alteration. More research into bull trout ecology in large river habitats is needed to improve our understanding of how adults establish migration patterns, what factors influence adult spatial distribution in winter, and how managers can protect and enhance fluvial populations. PMID:22655037

  7. Geological and petrophysical characterization of the Ferron Sandstone in Utah, for 3-D simulation of a fluvial-deltaic reservoir

    SciTech Connect

    Chidsey, T.C. Jr. [Utah Geological Survey, Salt Lake City, UT (United States)

    1995-06-01

    Fluvial-deltaic reservoirs contain the largest developed domestic oil reserves, and due to the high degree of reservoir heterogeneity, the largest amount of unrecovered oil of any type of developed reservoirs. The excellent outcrops of the fluvial-deltaic Ferron Sandstone Member of the Cretaceous Mancos Shale make the Coal Cliffs in east-central Utah a world-class area to study reservoir heterogeneity. With funding from the U.S. Department of Energy, a multidisciplinary team is developing a 3-D reservoir model for the Ferron Sandstone. Our work to date has consisted of: (1) determining geological and petrophysical properties of significant lithofacies, (2) developing new field methods, and (3) interpreting the stratigraphy regionally and within case-study areas. Numerous sections have been measured, described, and correlated to interpret of the sequence stratigraphy and lithofacies. Lithologic and paleocurrent data were entered into a database to construct statistical models, strip logs, and lithofacies maps. Several gamma-ray traverses were undertaken primarily for stratigraphic correlation. Numerous core plugs were obtained from various lithofacies for porosity, permeability, and other types of reservoir analyses. Permeability transects were completed across the proximal, middle, and distal portions of the delta-front sandstones. Six core holes were drilled in the central case-study area in a pattern similar to that drilled in an oil field. The data collected will be integrated into a 3-D representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve management of similar reservoirs worldwide through proper infill and extension drilling strategies, reduction of economic risks, increased recovery, and more reliable reserve calculations.

  8. Miocene and Pliocene lacustrine and fluvial sequences, Upper Ramparts and Canyon village, Porcupine river, east-central Alaska

    USGS Publications Warehouse

    Fouch, T.D.; Carter, L.D.; Kunk, M.J.; Smith, C.A.S.; White, J.M.

    1994-01-01

    Cenozoic strata exposed along the Porcupine River between the Upper Ramparts and Canyon Village, Alaska, can be divided into five unconformity-bounded units (sequences) which are: lower and middle Miocene unit A, the white sandy fluvial sequence with peat beds; middle Miocene unit B, the basalt sequence-part B1 is basalt, and part B2 is organic-rich sedimentary beds; upper Miocene unit C, mudrock-dominated lake sequence; late Miocene or Pliocene to Pleistocene unit D, terrace gravels, detrital organic matter and associated sediments, and Holocene unit E, mixed sand and gravel-rich sediment and other sedimentary material including peat and eolian silt. The sequence (unit A) of lower and middle Miocene fluvial deposits formed in streams and on flood plains, just before the inception of local volanism. Fossil pollen from unit A suggests conifer-dominated regional forests and cool temperate climates. Peat beds and lake deposits from unit B contain pollen that indicates a warmer temperate climate coinciding with the middle Miocene thermal maximum. The lake deposits (unit C) downstream from the basalts accumulated in a small basin which resulted from a hydrologic system that was dammed in the late Miocene but breached soon thereafter. The lower part of the terrace gravels (unit D) expresses breaching of the dammed hydrologic system (of unit C). The Porcupine River became a major tributary of the Yukon River in late Pleistocene time when Laurentide ice blocked drainage from the Yukon interior basins causing meltwater to spill over the low divide separating it from the Porcupine River drainage initiating erosion and capture of the Yukon interior basins. ?? 1994.

  9. Diagenesis and reservoir potential of Permian-Triassic fluvial/lacustrine sandstones in the southern Junggar basin, northwestern China

    SciTech Connect

    Tang, Zhaohui; Longstaffe, F.J. [Univ. of Western Ontario, London (Canada); Parnell, J. [Queen`s Univ. of Belfast (United Kingdom)

    1997-11-01

    The Junggar basin is one of the largest oil-producing areas in China, and contains Upper Permian lacustrine oil shales with some of the greatest hydrocarbon potential in the world. In this study, we present the diagenetic characteristics of Permian-Triassic sandstones from the southern Junggar basin and evaluate their reservoir potential. The uppermost Permian and Lower Triassic Cangfanggou Group in the southern Junggar basin is characterized by alternating fluvial and lacustrine deposits, whereas the Middle-upper Triassic Xiaoquangou Group was deposited predominantly in a lacustrine environment; fluvial and deltaic sedimentation was subordinate. The sandstones of the Cangfanggou and Xiaoquangou groups are volcanic litharenites. Their detrital modes and textures of volcanic fragments suggest a primarily andesitic/basaltic volcanic-arc provenance. Early diagenesis of the sandstones is characterized by nonferroan calcite cementation, grain-coating, pore-lining clay minerals, and the initial dissolution of detrital grains. Authigenic quartz; pore-filling phyllosilicates; pore-filling, grain-replacive zeolites; albitized detrital plagioclase; authigenic K-feldspar; illite; and late calcite dominate burial diagenesis. The formation of iron oxides and dissolution of calcite cement resulted from tectonic uplift during the Tertiary. Albitization and zeolite formation during burial are among the most pronounced diagenetic processes that affected these sandstones. Pore-filling clay minerals, calcite, and zeolites have substantially reduced sandstone porosity. However, appreciable primary porosity has been preserved by the formation of early clay coats and pore linings, which retarded further cementation. Secondary porosity is present to varying degrees in the sandstones and is the result of dissolution of unstable framework grains.

  10. The igapó of the Negro River in central Amazonia: Linking late-successional inundation forest with fluvial geomorphology

    NASA Astrophysics Data System (ADS)

    Montero, Juan Carlos; Latrubesse, Edgardo M.

    2013-10-01

    Despite important progress on Amazonian floodplain research, the flooded forest of the Negro River "igapó" has been little investigated. In particular, no study has previously focused the linkage between fluvial geomorphology and the floristic variation across the course of the river. In this paper we describe and interpret relations between igapó forest, fluvial geomorphology and the spatial evolution of the igapó forest through the Holocene. Therefore, we investigate the effect of geomorphological units of the floodplain and channel patterns on tree diversity, composition and structural parameters of the late-successional igapó forest. Our results show that sites sharing almost identical flooding regime, exhibit variable tree assemblages, species richness and structural parameters such as basal area, tree density and tree heights, indicating a trend in which the geomorphologic styles seem to partially control the organization of igapó's tree communities. This can be also explained by the high variability of well-developed geomorphologic units in short distances and concentrated in small areas. In this dynamic the inputs from the species pool of tributary rivers play a crucial role, but also the depositional and erosional processes associated with the evolution of the floodplain during the Holocene may control floristic and structural components of the igapó forests. These results suggest that a comprehensive approach integrating floristic and geomorphologic methods is needed to understand the distribution of the complex vegetation patterns in complex floodplains such as the igapó of the Negro River. This combination of approaches may introduce a better comprehension of the temporal and spatial evolutionary analysis and a logic rationale to understand the vegetation distribution and variability in function of major landforms, soil distributions and hydrology. Thus, by integrating the past into macroecological analyses will sharpen our understanding of the underlying forces for contemporary floristic patterns along the inundation forests of the Negro River.

  11. Palaeoenvironment and fluvial history of river Danube between the Neolithic settlement sites of Vinca and Starcevo, Serbia

    NASA Astrophysics Data System (ADS)

    Penezic, Kristina; Kadereit, Annette; Thiemeyer, Heinrich

    2013-04-01

    The Neolithic site of Vinca - Belo brdo (ca. 5600 - 4200 BC) is located on the right bank of the Danube River, some 14 km downstream of the city of Belgrade in Serbia. The significance of the Vinca settlement is in its long occupational history, which produced more than 9 meters of settlement layers that provided archaeologists with an understanding of the chronological sequencing and development from the Middle to Late Neolithic in central Serbia. Vinca - Belo brdo was designated as the locus typicus for the Vinca Culture and is considered by many archaeologists as one of the most important sites of the European Neolithic. On the opposite, left side of the river Danube, the early Neolithic site of Starcevo is situated. It spans through the early Neolithic period dated to the seventh and the sixth millennium BC and it is the locus typicus for the Starcevo culture that on the territory of modern-day Serbia precedes the Vinca culture. The vicinity of the Danube influenced the development of these settlements and the relationship between them. Serving as a landmark, border, source of food, but also endangering the sites by a shifting stream course, the Danube is essential. Therefore it is important to define the position of the river during the occupational span of the Neolithic settlements and later. In our study, the early to mid-Holocene environmental changes of the fluvial landscape between the two Neolithic settlement sites are explored. We present preliminary results of recent geomorphological, sedimentological and archaeological investigations, as well as OSL dating, which were combined with relevant information from historical maps and satellite imagery in order to reconstruct the fluvial palaeolandscape.

  12. Increased Fluvial Dissolved Organic Carbon Fluxes over 130 Years of Land-Use Change in the Thames Basin

    NASA Astrophysics Data System (ADS)

    Noacco, V.; Howden, N. J. K.; Wagener, T.; Worrall, F.

    2014-12-01

    This study investigates drivers of changing dissolved organic carbon (DOC) export in the UK's River Thames basin between 1881 and 2011. Specifically, we consider how impacts of land-use change drive increases in DOC concentrations and fluxes at the basin outlet. First, we estimate soil organic carbon (SOC) stocks in the Thames basin for the period. Second, SOC losses due to land-use change are partitioned into DOC lost to surface waters through runoff, DOC leached into deeper soils and groundwater, and losses to the atmosphere as CO2. SOC stocks for each year are calculated from a large database of typical SOC levels for land-uses present in the Thames basin and are combined with literature values of transition times for SOC to adjust to a new level following land-use change. We also account for climate change effects on SOC stock due to temperature increases, which reduces SOC stocks as soil organic matter turnover rates increase. Soil carbon fluxes are calculated as the inter-annual change in SOC. We use a 130 year record of DOC concentration in the Thames, and parameters from previous long-term nitrate modeling, to constrain estimates of fluvial DOC rises caused by SOC losses. We developed a sewage model to evaluate the relative contribution of point and diffuse sources to the total DOC flux. The results show that sewage effluent point sources do not contribute to DOC concentration at the monitoring point, except for isolated periods of exceptionally low flow. Our work shows for the majority of years, diffuse sources are the main contributor to annual DOC loads. Moreover even though there are many small inter-annual variations in DOC concentration, the major change in both estimated SOC storage and fluvial DOC export occurred during WWII due to substantial changes in land-use, the legacy of which continues to date.

  13. Historical impact of dams and weirs on the fluvial system in the low order rivers of central Europe

    NASA Astrophysics Data System (ADS)

    Wilder, Nicole; Larsen, Annegret; Lungershausen, Uta

    2014-05-01

    Central European streams have been influenced by humans to varying degrees for at least ~ 1000 years. In the low mountainous areas of central Europe, rivers were commonly exploited for energy production (mills) or irrigation (hay production). Separately, changes to these fluvial systems have been documented throughout this same time period, but generally attributed to changes in land use. In particular, increase in agriculture at this time is known to have caused widespread hillslope soil erosion and therefore increased the sediment load delivered to these rivers. However, valley bottom damming is also an important river modification that has been largely overlooked within Europe, even though the history of damming low-order streams reaches back until at least medieval times. In this study, we aim to track the historic changes in the fluvial system of two central European 1st to 3rd order mountain catchments and attribute them to either i) land-use change or ii) valley bottom damming, or some combination of both. As a first step, we analyse the changes of dam location and density, river flow pattern, sinuosity, and land-use in the five separate time periods available from i) historic maps: 1808-1861 AD (Bayern), 1840-1861 AD (Hessen), 1844-1848 AD (Bayern), and ii) topographic maps from the mid 20th century and 2012. Qualitative data from maps older than 1800 AD are also integrated into the database (i.e. dam location only, not morphology), along with Corine Land Cover data. These results highlight the utility of combining historical and modern information on river morphology to determine the river response to land use change and flow regulation.

  14. Identificacin de deslizamientos de terreno utilizando fotos areas de Ponce, Puerto Rico

    E-print Network

    Gilbes, Fernando

    Identificación de deslizamientos de terreno utilizando fotos aéreas de Ponce, Puerto Rico Rosimar sobre el área. Para el caso de Ponce, se tenían disponibles fotos aéreas que fueron toma- das por una de esta técnica. Palabras claves: clasificaciones, deslizamientos, ENVI, fotos, percepción remota

  15. Rastreamento de Multiplas Larvas utilizando Tecnicas de Vis~ao Computacional: Resultados Preliminares

    E-print Network

    Lewiner, Thomas (Thomas Lewiner)

    Grupo de Pesquisa INOVISAO para contagem de larvas vivas em testes de larvicidas para o mosquito daRastreamento de M´ultiplas Larvas utilizando T´ecnicas de Vis~ao Computacional: Resultados resultados preliminares de um experimento com filtros de part´iculas para rastreamento de m´ultiplas larvas

  16. ContentNet: um framework para interoperabilidade de contedos educacionais utilizando a plataforma IMS

    E-print Network

    Endler, Markus

    ContentNet: um framework para interoperabilidade de conteúdos educacionais utilizando a plataforma, a plataforma IMS, um consórcio de organizações acadêmicas, comerciais e governamentais, vem desenvolvendo e conteúdos educacionais disponíveis em servidores compatíveis com a plataforma IMS. Palavras­chave: Conteúdo

  17. The Importance of Actualistic Source-to-Sink Sand Provenance Studies in Illuminating the Nature of Ancient Fluvial Systems From the Deep-Marine Clastic Successions They Sourced

    NASA Astrophysics Data System (ADS)

    Marsaglia, K. M.; Parra, J. G.; Dawson, S.

    2006-12-01

    Successions of gravity-flow deposits in deep-marine fan systems have the potential to record the evolution of their fluvial source region as well as specific tectonic, climatic, eustatic and anthropogenic events. Deciphering these signals involves the description and quantification of key sediment attributes such as fan volume, the rate of sediment accumulation, the frequency of depositional events, sediment texture, and sediment composition. Sediment composition/provenance provides insight into the nature of the fluvial source, including drainage basin geology and drainage development. For example, Marsaglia et al. (1995) demonstrated a connection between source river lengthening owing to eustatic change and sand composition in Quaternary turbidite successions of the Santa Barbara Basin at Ocean Drilling Program (ODP) Site 893. In contrast, longer-term compositional trends recognized in the Mesozoic to Cenozoic rift-to-drift successions cored by various ODP legs on the North Atlantic margins are more likely associated with continental margin drainage development and fluvial system evolution (Marsaglia et al., in press). These two connections between sink and source were made possible by well-documented petrologic data sets for both modern onshore fluvial systems and older offshore deep-marine successions, but in each case different workers collected the onshore and offshore data sets. In the Waipaoa River Sedimentary System of North Island, New Zealand we have taken a different, more holistic approach, with a limited and linked group of researchers and sample data base covering the complete system. The study area is an active forearc margin characterized by uplifted and deformed sedimentary successions and periodic input of arc-derived ash. Recently, the modern onshore system has been thoroughly documented via studies of the petrology of outcropping Mesozoic to Cenozoic units, fluvial terrace deposits, and modern fluvial sediments (e.g., James et al., in press). Now we are building on that data set and moving from source-to-sink to trace sandy sediment through the system out onto the shelf and slope where it has been encountered in shallow cores. Lessons learned onshore, such as a distinct compositional dependence on grain size and the relationships of bedrock geology to certain sand grain types, also apply to these offshore core samples. Many of the sandy intervals are largely composed of reworked tephra from Taupo eruptions, whereas quartz and feldspar dominate finer sand samples. Lithic-dominated sands are less common and coarser grained. Isolated greywacke gravel clasts indicate that at some point coarse sediment "leaked" into the basin from the south. The volumetric importance of this extrabasinal input can be assessed by looking at the types and proportions of lithic fragments within the finer sand fraction.

  18. Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

    NASA Astrophysics Data System (ADS)

    Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

    2014-05-01

    Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the <63 micron fraction of sediment sources including forested topsoils (Cs-137 11.28 +/- 0.75 Bq/kg; Pb-210ex 181.87 +/- 20.00 Bq/kg), agricultural topsoils (Cs-137 3.21 +/- 0.26 Bq/kg; Pb-210ex 29.59 +/- 10.94 Bq/kg) and sub-soils from channel banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the upper reach (<10 km long), while sub-soils account for 90 to 100% of sediment entering and being transported in the remaining ~50 km of the system. This shift in dominant sediment source material coincided with a large increase in channel cross sectional area (~20 to >200 m2) downstream, with channel expansion and gullies contributing fine sediment to the system. A lack of topsoil being supplied to the channel suggests minimal lateral connectivity between the catchment and the trunk stream in all areas apart from the upper catchment. The enlargement and entrenchment of the channel downstream has also resulted in lateral disconnection between the channel and floodplain. In this case, a rapid reduction in radionuclide concentrations downstream does coincide with hydrogeomorphic changes, supporting their use for studying short-term sediment dynamics. These findings highlight the importance of understanding hydrogeomorphic processes and connectivity when interpreting sediment source and tracer data.

  19. Supercritical strata in Lower Paleozoic fluvial rocks: a super critical link to upper flow regime processes and preservation in nature

    NASA Astrophysics Data System (ADS)

    Lowe, David; Arnott, Bill

    2015-04-01

    Recent experimental work has much improved our understanding of the lithological attributes of open-channel supercritical flow deposits, namely those formed by antidunes, chutes-and-pools and cyclic steps. However their limited documentation in the ancient sedimentary record brings into question details about their geological preservation. Antidune, chute-and-pool and cyclic step deposits are well developed in sandy ephemeral fluvial deposits of the Upper Cambrian - Lower Ordovician Potsdam Group in the Ottawa Embayment of eastern North America. These high energy fluvial strata form dm- to a few m-thick units intercalated within thick, areally expansive successions of sheet sandstones consisting mostly of wind ripple and adhesion stratification with common deflation lags. Collectively these strata record deposition in a semi-arid environment in which rare, episodic high-energy fluvial events accounted for most of the influx of sediment from upland sources. Following deposition, however, extensive aeolian processes reworked the sediment pile, and hence modified profoundly the preserved stratigraphic record. Antidune deposits occur as 0.2 - 1.6 m thick cosets made up of 2 - 15 cm thick lenticular sets of low angle (? 20o) cross-stratified, medium- to coarse-grained sandstone bounded by low-angle (5 - 15o) concave-upward scours and, in many cases, capped by low angle (10 - 15o) convex-upwards symmetrical formsets. Chute-and-pool deposits form single sets, 5 - 55 cm thick and 0.6 - 6 m wide, with scoured bases and low to high angle (5 - 25o) sigmoidal cross-strata consisting of medium- to coarse-grained sandstone. Cyclic step deposits consist of trough cross-stratified sets, 20 cm - 1.6 m thick, 2.5 - 12 m long and 7 - 35 m wide, typically forming trains that laterally are erosively juxtaposed at regularly-spaced intervals. They are composed of medium- to coarse-grained sandstone with concave-up, moderate to high angle (15 - 35o) cross-strata with tangential bases that conform to the shape of the basal bounding surface of the set. Antidune and cyclic step deposits are common and fill 0.4 - 1.8 m deep channels, which then are generally overlain by extensive (>1 km) aeolian deflation surfaces. Chute-and-pool strata, however, are rare and only occur as isolated scour-filling sets within unconfined floodplain deposits. Nowhere in outcrop do different kinds of supercritical bedform deposits interfinger or appear related to the same flow event, suggesting that individual packages of supercritical strata were deposited by discreet, rapidly waning flows with little time for incremental growth or deposition under changing flow conditions. The stratal characteristics and geometries of channel-filling antidune and cyclic step cosets in the Potsdam are similar to those produced in steady experimental flows with high rates of aggradation. Similar conditions in the Potsdam were probably attained because the flows were channelized, which also caused the freshly deposited sediment to lie beneath the water table, and hence beneath the effects of extensive post-flood aeolian deflation. Conversely, scour-filling chute-and-pool deposits formed on the floodplain where highly unsteady, erosive and rapidly waning unconfined flows formed isolated, partly-filled, erosively-based, ephemeral structures. Moreover, being formed on the surface of the floodplain subjected these deposits to extensive post-depositional reworking, and as a consequence caused them to be poorly preserved.

  20. Progressive rock slope failure resulting from fluvial incision and far-field stress changes in alpine landscapes

    NASA Astrophysics Data System (ADS)

    Leith, K.; Moore, J. R.; Loew, S.; Krautblatter, M.

    2013-12-01

    Modifications to rock slope morphology are commonly associated with the destabilization of local rock masses where shear, normal, or tensile stress changes cause in situ stresses to exceed intact or rock mass failure envelopes. Such destabilization is most commonly attributed to ';debuttressing' causing a loss of support from adjacent bodies, or a reduction in effective rock mass strength as critical planes of weakness are ';undercut' by erosional processes. Lower magnitude stress changes which approach the brittle failure envelopes are often implicated in progressive rock slope failure, as local stress concentrations propagate existing fractures or weaken existing joints. We model the development of long-term in situ stresses within an alpine valley affected by ongoing tectonic and erosional processes. We allow for the mechanical effects of long-term bedrock strength limits, and analyze the magnitude of far-field stress changes associated with 100 m of fluvial incision at the axis of a 3000 m wide, 2500 m deep alpine valley. Our model configuration mirrors the erosional history of the Matter Valley (southern Swiss Alps) at the location of the 30 x 106 m3 Randa rock slope failure. We find that incision focuses stresses at the valley floor, reducing stress magnitudes throughout the remainder of the landscape. This effect is particularly strong near the valley shoulder, where decreases in shear stress are approximately half those of normal stresses. Although the magnitude of changes are relatively low (10's to 100's of kPa), we find incision may have had a negative impact on the stability of rock slopes over 1000 m from the valley axis, perhaps initiating progressive failure of the Randa rock slope. Such progressive failure is particularly important in alpine regions, as its initiation requires relatively minor morphological change, and the resulting strength degradation modulates temporal increases in rock slope sensitivity. Our proposition is supported by the presence of glacial striations within large tension cracks above the Randa rock slope failure. These formed during, or prior to the Last Glacial Maximum, indicating progressive rock slope failure was already well underway by this time, and along with an analysis of temporal fluvial incision, suggest destabilization most likely initiated during the interglacial at MIS 3. In situ stress changes associated with 100 m of river incision at the axis of our model valley. Incision is simulated by removing a 100 m deep wedge of rock from the valley axis, consistent with estimated stream incision at the toe of the Randa rock slope. The Randa failure geometry is overlaid on the left hand side of the model for comparison. Stress changes are determined by differencing the pre- and post-incision stress fields.

  1. Folded fluvial terraces and the deforming of a new uplifted region in the mountain front the Qilian Shan Mountain, China

    NASA Astrophysics Data System (ADS)

    Hu, X.; Pan, B.; Wang, J.; Hu, Z.

    2014-12-01

    How the Tibetan Plateau is extended is one of the key problems to understand the earth crust evolution in the frame of plate tectonics. A newly uplifting area, the Dahe region, locating between the Yumu Shan Mountain and the Qilian Shan Mountain, in the northeastern Tibetan Plateau, would supply us a fresh sight on the process that how the plateau is extended to a new region. The Dahe region was a relatively depressing or stable area before late Pleistocene, and received thick fluvial sediment derived from the Qilian Shan in the south. In late Pleistocene, the old depositing surface Sp (alluvial fan surface) was deeply cut by the Dahe River. Below the old depositing surface, four staircases of strath terraces (strath is the old fluvial deposition) are formed by the Dahe River, and each terrace surfaces are buried by aeolian loess. By the OSL dating on overlying loess on the terraces and correlating to climate records, we obtain formation ages (terrace surface abandoning time) of the four terraces (from high to low): 128.2 ±9.8 ka, 109.6±20.8 ka, 96.3 ±9.0 ka, and 15.9 ±2.5 ka. We obtain the extrapolated Sp age of 160 ±25 ka, which represents the time when the fan depositing was end and river cutting and eroding was started in the Dahe region. By the uplifted terrace staircases and warped long profiles of terraces, we can find that the region is not only experiencing regional uplifting but also folding deformation. Through analyzing the geometry of the deforming terrace surfaces, we propose that a new blind thrust fault was derived from the main decollement in the upper crust, and thus the growing fault deduced the uplift of the Dahe region and the folding near the fault tip. The growth of the Dahe region, which is sandwiched by the Yumu Shan and the Qilian Shan, both uplifted millions years ago, suggests that northeastern extending of the plateau is in the form of new fault-fold system growing in mountain front and back.

  2. Magnetic characteristics of aeolian and fluvial sediments and onset of dust accumulation at Lake Yoa (northern Chad) during the Holocene

    NASA Astrophysics Data System (ADS)

    Just, Janna; Kröpelin, Stefan; Karls, Jens; Rethemeyer, Janet; Melles, Martin

    2014-05-01

    The Holocene is a period of fundamental climatic change in North Africa. Humid conditions during the Holocene Humid Period have favored the formation of big lake systems (e.g. Lake Megachad) and are evident in terrestrial and marine archives. Only very few of these lakes persist until today. One of them is Lake Yoa (19°03'N/20°31'E) in the Ounianga Basin, Chad, which maintains its water level by ground water inflow. Here we present the magnetic characteristics of a continuous 16 m long sediment record (Co1240) from Lake Yoa, retrieved in 2010 within the framework of the Collaborative Research Centre 806 - Our Way to Europe (Deutsche Forschungsgemeinschaft). The sedimentary section covers the past 11,000 years. In an earlier core (Kröpelin et al. 2008), a humid climate during the Mid-Holocene is indicated by fresh-water conditions in the lake. At about 4,000 cal. years BP, a fresh-to-saline transition is reflected in the record. However, a major rise in magnetic susceptibility, interpreted as an increase in the accumulation of wind-blown material, is only visible after 3,000 cal. years BP. Beyond using the concentration of magnetic minerals (susceptibility), environmental magnetic proxies, e.g. magnetic grain size and the composition of the magnetic mineral fabric, are often used as paleoenvironmental indicators. The underlying assumption is that the formation of magnetic minerals during pedogenesis is catalyzed by precipitation and soil-temperature. The application of magnetic proxies as reliable climofunctions has, however, recently been challenged. Possible problems are that soil formation might not reach an equilibrium state if climate perturbations are too short (e.g. hundreds of years) or that other variables such as soil organic carbon and vegetation have varied. In this study, we will focus on the variability of magnetic parameters in Lake Yoa sediments and its implication for the regional environmental development throughout Holocene times. 400 discrete samples will be analyzed using a cryogenic magnetometer. The magnetic grain size will be used to identify the initiation of increased accumulation of aeolian material. By analyzing Isothermal Remanent Magnetization acquisition curves, fluvial and aeolian end-members will be characterized in terms of magnetic mineralogy. Furthermore, a possible climate-induced impact on the formation of pedogenetic magnetic minerals in the source area of fluvial and aeolian sediments will be evaluated by a comparison of the environmental magnetic with organic proxies.

  3. Inter- and intra-annual variability of fluvial sediment transport in the proglacial river Riffler Bach (Weißseeferner, Ötztal Alps, Tyrol)

    NASA Astrophysics Data System (ADS)

    Baewert, Henning; Weber, Martin; Morche, David

    2015-04-01

    The hydrology of a proglacial river is strongly affected by glacier melting. Due to glacier retreat the effects of snow melt and rain storms will become more important in future decades. Additionally, the development of periglacial landscapes will play a more important role in the hydrology of proglacial rivers. The importance of paraglacial sediment sources in sediment budgets of glacier forefields is increasing, while the role of glacial erosion is declining. In two consecutive ablation seasons the fluvial sediment transport of the river Riffler Bach in the Kaunertal (Tyrol/Austria) was quantified. The catchment area of this station is 20 km² with an altitudinal range from 1929 m to 3518 m above msl. The "Weißseeferner" glacier (2.34 km² in 2012) is the greatest of the remaining glaciers. An automatic water sampler (AWS 2002) and a probe for water level were installed were installed at the outlet of the catchment. In order to calculate annual stage-discharge-relations, discharge (Q) was repeatedly measured with current meters. Concurrent to the discharge measurements bed load was collected using a portable Helley-Smith sampler. Bed load (BL) samples were weighted and sieved in the laboratory to gain annual bed load rating curves and grain size distributions. In 2012, 154 water samples were sampled during 7 periods and subsequently filtered to quantify suspended sediment concentrations (SSC). A Q-SSC-relation was calculated for every period due to the high variability in suspended sediment transport. In addition, the grain size distribution of the filtered material was determined by laser diffraction analysis. In 2013, the same procedure was performed for 232 water samples which were collected during 9 periods. Meteorological data were logged at the climate station "Weißsee", which is located in the centre of the study area. First results show a high variability of discharge and solid sediment transport both at the inter-annual as well as at the intra-annual timescale. In 2012, a larger amount of sediment was transported compared to 2013. A higher runoff during the snowmelt period 2012 and a heavy rain fall event in late August 2012 were the main reasons. Only 8 of 16 Q-SSC-relations show causal dependency. Thus, indicating that sediment transport strongly depends on the availability of sediment and the coupling of sediment sources to the fluvial system.

  4. Climatic Controls on Fluvial Cut-and-Fill Cycles in Drainages with In-stream Wetlands in the Central Andes

    NASA Astrophysics Data System (ADS)

    Rech, J. A.; Latorre, C.

    2004-12-01

    Fluvial systems that possess in-stream wetlands, or marshes, are common in arid environments where water-tables are emergent and large discharge events uncommon. These streambeds are protected from erosion by a dense cover of hydrophyllic and phreatophytic vegetation. Along the Pacific slope of the Central Andes in northern Chile (~20°-26°S), which includes some of the driest sectors of the Atacama Desert, in-stream wetlands occur in deeply incised bedrock canyons on the Andean slope and piedmont. Over the last several years we have compiled a detailed record of late Pleistocene and Holocene vegetation changes along the Pacific slope of the Andes through the collection, analysis, and radiocarbon determination of over 180 rodent middens. Rodent middens record past changes in precipitation levels by tracking the downslope migrations of plant species into the hyperarid desert. We have also assembled a record of the cut-and-fill cycles of several fluvial systems with in-stream wetlands located at various distances (5-50 km) from the zone of ground-water recharge in the High Andes through stratigraphic mapping and the radiocarbon dating of over 100 samples of organic material within these wetlands. Combined, this well-dated record of hillslope vegetation and stream aggradation and incision allows us to assess the influence of climatic change on stream processes, including the nature of stream response, the sensitivity of different stream systems to climatic change, and the response times of streams to climate changes that vary in distance from ground-water recharge zones. The combined data set shows that in-stream wetland aggradation is directly linked to changes in climate, with aggradation occurring during wetter climatic periods when water tables are high. Incision occurs during dry climatic periods when water tables are lower and streambed sediments are no longer anchored by dense vegetation. Streams that are closer to ground-water recharge zones are more sensitive to minor changes in precipitation, whereas more distant streams with larger catchment areas appear to be less sensitive. Response times of stream incision to the initiation of drought conditions appear to be ~500 years.

  5. Comment on “Human impacts on headwater fluvial systems in the northern and central Andes” (Carol P. Harden, Geomorphology 79, 249 263)

    NASA Astrophysics Data System (ADS)

    Buytaert, Wouter; De Bièvre, Bert; Celleri, Rolando; Cisneros, Felipe; Wyseure, Guido; Deckers, Seppe

    2008-04-01

    The high altitude grasslands of the tropical Andes, known as páramo, are a very fragile and unique ecosystem. Despite increasing human activities, many of its geomorphological and hydrological processes are still very poorly understood. We therefore welcome the paper of Harden [Harden, C.P., 2006. Human impacts on headwater fluvial systems in the northern and central Andes. Geomorphology 79, 249-263.] about "Human impacts on headwater fluvial systems in the northern and central Andes" as a valuable contribution to a better understanding of this complex ecosystem. However, in view of the available literature, we would like to complement the interpretation of the presented results and discuss some of the claims made in the paper.

  6. EVALUACIN Y CREACIN DE DOS CORREDORES ECOLGICOS: UTILIZANDO SISTEMAS DE INFORMACIN GEOGRFICA

    E-print Network

    Gilbes, Fernando

    EVALUACI�N Y CREACI�N DE DOS CORREDORES ECOL�GICOS: UTILIZANDO SISTEMAS DE INFORMACI�N GEOGRÁFICA Y TELEDETECCI�N (Al este de la Habana, Cuba y al este de San Juan, Puerto Rico) Dr. José Seguinot Barbosa Puerto Rico jseguinot@rcm.upr.edu TEL. 758-2525 Ext.2925 Dr. José Luis Batista Silva y MS Miguel Sánchez

  7. New insight into the sedimentology and stratigraphy of the Dur At Talah tidal-fluvial transition sequence (Eocene-Oligocene, Sirt Basin, Libya)

    NASA Astrophysics Data System (ADS)

    Abouessa, Ashour; Pelletier, Jonathan; Duringer, Philippe; Schuster, Mathieu; Schaeffer, Philippe; Métais, Eddy; Benammi, Mouloud; Salem, Mustafa; Hlal, Osama; Brunet, Michel; Jaeger, Jean-Jacques; Rubino, Jean-Loup

    2012-04-01

    The Dur At Talah escarpment is exposed in the Abu Tumayam Trough at the southern part of the Sirt Basin, central Libya. The cliff (˜145 m high and ˜150 km long) is oriented along an E-W axis and faces southward. Only a few field studies have been previously carried out in this area, and these were mainly focused on the succession's famous vertebrate fossil-content. The reconstruction of the depositional environments, which is the purpose of this paper, remained poorly documented. In this study, the uppermost Eocene rock succession composing the Dur At Talah escarpment is divided into two stratigraphic units: the New Idam Unit at the base composed of highly bioturbated fine sand/claystone alternations, and the Sarir Unit at the top dominated by medium to very coarse grading sometimes to microconglomeratic sandstones. This complete succession is built up of shallow marine (New Idam Unit) to fluvial (upper part of Sarir Unit) deposits passing through a "marine/fluvial" transition zone (lower Sarir Unit). The stratigraphic succession suggests a global regressive trend. The marine part of the New Idam Unit is dominated by deposits attributed to tidal depositional environments including tidal flat, tidal channel and tidal bars as well as biostroms of oyster shells at the base of the unit. The lower part of the Sarir Unit appears to be deposited in a fluvial influenced, tide-dominated environment. The upper part of the Sarir Unit, made of coarse-grained to microconglomeratic sandstones interbedded with paleosoil horizons, is interpreted as being fluvial.

  8. Late quaternary evolution of the Meuse fluvial system and its sediment composition: a reconstruction based on bulk sample geochemistry and forward modelling

    Microsoft Academic Search

    L. A. Tebbens

    1999-01-01

    All fluvial systems ultimately drain into alluvial basins, where the weathering products of their upstream drainage areas accumulate over a time-span varying from 10 0<\\/SUP>to 10 6<\\/SUP>years. Most silted-up alluvial basins are low-gradient deltas that are densely populated, because their high fertility maintains a high agricultural potential. Global warming due to increased concentrations of greenhouse gases in the Earth's atmosphere

  9. Identification and evaluation of fluvial-dominated deltaic (Class 1 oil) reservoirs in Oklahoma. Quarterly technical progress report, January 1, 1995March 31, 1995

    Microsoft Academic Search

    C. J. Mankin; M. K. Banken

    1995-01-01

    The Oklahoma Geological Survey (OGS), the Geological Information Systems department, and the School of Petroleum and Geological Engineering at the University of Oklahoma are engaging in a program to identify and address Oklahoma`s oil recovery opportunities in fluvial-dominated deltaic (FDD) reservoirs. This program includes the systematic and comprehensive collection and evaluation of information on all of Oklahoma`s FDD reservoirs and

  10. Identification and Evaluation of Fluvial-Dominated Deltaic (Class 1 Oil) Reservoirs in Oklahoma: Yearly technical progress report for January 1December 31, 1996

    Microsoft Academic Search

    M. K. Banken; R. Andrews

    1997-01-01

    The Oklahoma Geological Survey (OGS), the Geo Information Systems department, and the School of Petroleum and Geological Engineering at the University of Oklahoma are engaged in a five-year program to identify and address Oklahoma`s oil recovery opportunities in fluvial-dominated deltaic (FDD) reservoirs. This program includes a systematic and comprehensive collection and evaluation of information on all FDD oil reservoirs in

  11. Investigation of river network evolution using luminescence dating and heavy mineral analysis of Late-Quaternary fluvial sands from the Great Hungarian Plain

    Microsoft Academic Search

    Andrew S. Murray; Annamária Nádor; Árpád Magyari

    2007-01-01

    To reconstruct the evolution of Late-Quaternary river network in the southeastern part of the Great Hungarian Plain, we have used optically stimulated luminescence (OSL) and heavy mineral analysis of 25 sand samples from the upper 2–8m of the fluvial units, complemented by four radiocarbon ages. The estimated OSL depositional ages vary between 10 and 47ka. The heavy mineral composition of

  12. Regional paleoclimatic and stratigraphic implications of paleosols and fluvial\\/overbank architecture in the Morrison Formation (Upper Jurassic), Western Interior, USA

    Microsoft Academic Search

    Timothy M Demko; Brian S Currie; Kathleen A Nicoll

    2004-01-01

    Paleosols in the Morrison Formation (Upper Jurassic) from the Western Interior and Colorado Plateau regions occur in fluvial\\/overbank and marginal-lacustrine depositional facies associated with aggradational settings, and at sequence-bounding unconformities that mark divisions between major aggradational and degradational successions. Pedogenic features within these horizons preserve important contextual information about the local and regional paleoclimate and paleoenvironment in which the soils

  13. Mercury, copper and zinc contamination in soils and fluvial sediments from an abandoned gold mining area in southern Minas Gerais State, Brazil

    Microsoft Academic Search

    Ricardo Cesar; Silvia Egler; Helena Polivanov; Zuleica Castilhos; Ana Paula Rodrigues

    Mercury, zinc and copper contamination was evaluated in soils and fluvial sediments from an abandoned gold mining site at\\u000a Descoberto Municipality (southern Minas Gerais State, Brazil). Metals bioavailability and potential mobility were studied\\u000a through physical, chemical and mineralogical characterization, geoaccumulation indexes calculations, mercury speciation and\\u000a determination of potentially bioavailable contents of zinc and copper. Values of pH were in the

  14. Impacts of Fluvial Fine Sediments and Winter Storms on a Transgressive Shoal, off South-Central Louisiana, U.S.A

    Microsoft Academic Search

    D. Kobashi; F. Jose; G. W. Stone

    2007-01-01

    KOBASHI, D., JOSE, F., AND STONE, G.W., 2007. Impacts of Fluvial Fine Sediments and Winter Storms on a Transgressive Shoal, off South-Central Louisiana, U.S.A. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 858 - 862. Gold Coast, Australia, ISSN 0749.0208 Ship Shoal, a transgressive sand shoal off South-Central Louisiana and one of the potential sand

  15. Depositional mechanisms and facies models of intertonguing aeolian environment and fluvial milieu in the middle buntsandstein of the mid-european triassic basin

    Microsoft Academic Search

    Detlef Mader

    Intertonguing aeolian sand seas and fluvial braidplains occur abundantly in the upper part of the Middle Buntsandstein in various parts of the Mid-European Triassic Basin and are especially well-developed in the Eifel North-South-zone at the western margin of the depositional area. Based on assessment of the Buntsandstein regions and on comparative evaluation of other examples of interference between aeolian environment

  16. Identification and evaluation of fluvial-dominated deltaic (Class 1 oil) reservoirs in Oklahoma. Yearly technical progress report, January 1December 31, 1993

    Microsoft Academic Search

    C. J. Mankin; M. K. Banken

    1994-01-01

    The Oklahoma Geological Survey (OGS), the Geological Information Systems department, and the School of Petroleum and Geological Engineering at the University of Oklahoma are engaged in a five-year program to identify and address Oklahoma`s oil recovery opportunities in fluvial-dominated deltaic (FDD) reservoirs. This program includes the systematic and comprehensive collection, evaluation, and distribution of information on all of Oklahoma`s FDD

  17. Identification and evaluation of fluvial-dominated deltaic (Class 1 oil) reservoirs in Oklahoma. Yearly technical progress report, January 1December 31, 1994

    Microsoft Academic Search

    C. J. Mankin; M. K. Banken

    1995-01-01

    The Oklahoma Geological Survey and the University of Oklahoma are engaged in a five-year program to identify and address Oklahoma`s oil recovery opportunities in fluvial-dominated deltaic (FDD) reservoirs. This program includes the systematic and comprehensive collection, evaluation, and distribution of information on all of Oklahoma`s FDD oil reservoirs and the recovery technologies that can be applied to those reservoirs with

  18. Optimal oil recovery strategies in Miocene transgressive-barrier, coastal-plain, and mixed-load fluvial systems in the Mioceno Norte Area, Lake Maracaibo, Venezuela

    SciTech Connect

    Ambrose, W.A.; Wang, F.P.; Akhter, M.S.; Skolnakorn, J. [Univ. of Texas, Austin, TX (United States)] [and others

    1996-08-01

    Miocene oil reservoirs in the 30-km{sup 2} Mioceno Norte area are estimated to have a recovery efficiency of only 27 percent at the end of primary recovery operations at the current 40-acre well spacing. Although this area has produced oil since the 1930s, appreciable volumes of oil remain in multiple, poorly contacted reservoir compartments. Strategic development of these compartments could improve ultimate recovery up to an additional 15 to 20 percent of the original oil in place. Multiple Miocene regressive-transgressive episodes in the Maracaibo Basin resulted in a complex reservoir architecture. Basal Miocene fluvial deposits, deposited during a forced regression, are overlain by shelf and transgressive barrier-island deposits of a highstand systems tract. Episodes of upper Miocene fluvial and lacustrine-fill deposits, bounded by continuous paleosol marker beds, record climate changes or intermittent tectonic activity resulting in reorganization of dip-dispersal systems. We used an integrated reservoir-characterization program incorporating structural, stratigraphic, seismic, palynological, petrophysical, petrographic, petroleum-engineering, and volumetric analyses to target areas for strategic oil recovery. Remaining oil is inferred to occur mainly in narrow (less than 2000 in wide), uncontacted or poorly contacted fluvial-and distributary-channel sandstones commonly projected between existing well spacing. Additional remaining oil exists in tidal-channel and backbarrier areas where washover-fan sandstones pinch out into muddy lagoonal-fill deposits.

  19. Fluvial sedimentology and basin analyses of the Permian Fairchild and Buckley formations, Beardmore Glacier region, and the Weller Coal Measures, southern Victoria Land, Antarctica

    SciTech Connect

    Isbell, J.L.

    1990-01-01

    The Beardmore Glacier region contains a 1-km-thick Permian fluvial sequence that was deposited in an elongate basin along the margin of the East Antarctica craton. Fluvial architecture, sandstone composition and paleocurrents within the basin record a change from an early Permian cratonic to a late Permian foreland basin. The Lower Permian Fairchild Formation consists entirely of overlapping channel-form sandstone bodies deposited by braided streams. Arkosic sandstone was deposited by SE flowing streams. Fairchild strata record slow subsidence within a broad cratonic basin. The Lower to Upper Permian Buckley Formation consists of an arkosic lower member and a volcaniclastic upper member. Paleocurrents which consist of transverse and longitudinal paleocurrents, suggest a cratonward migration of the basin axis through time. The Buckley Formation was deposited within a braided stream setting and is an important unit because it contains interstratified channel-sandstone sheets, shale and coal, along with evidence of channel-belt avulsions. Sandstone sheets predominate at the base of the formation, while flood-plain deposits thicken and increase in abundance upward. The interaction between fluvial processes and subsidence rates produced this alluvial stratigraphy. The Lower Permian Weller Coal Measures in southern Victoria Land were deposited within a narrow basin located cratonward of the foreland basin. Basin geometry and depositional patterns are similar to those of fault-bounded basins. Although basin formation is not constrained, deposition of the Weller was contemporaneous with the development of the foreland basin. This suggests a relationship between subsidence within the two basins.

  20. Tectonic implications of fluvial incision and pediment deformation at the northern margin of the Central Anatolian Plateau based on multiple cosmogenic nuclides

    NASA Astrophysics Data System (ADS)

    Yildirim, Cengiz; Schildgen, Taylor F.; Echtler, Helmut; Melnick, Daniel; Bookhagen, Bodo; ?iner, Attila; Niedermann, Samuel; Merchel, Silke; Martschini, Martin; Steier, Peter; Strecker, Manfred R.

    2013-09-01

    document Quaternary fluvial incision driven by fault-controlled surface deformation in the inverted intermontane Gök��rmak Basin in the Central Pontide mountains along the northern margin of the Central Anatolian Plateau. In-situ-produced 10Be, 21Ne, and 36Cl concentrations from gravel-covered fluvial terraces and pediment surfaces along the trunk stream of the basin (the Gök��rmak River) yield model exposure ages ranging from 7 ± 1 ka to 346 ± 45 ka and average fluvial incision rates over the past ~350 ka of 0.28 ± 0.01 mm a-1. Similarities between river incision rates and coastal uplift rates at the Black Sea coast suggest that regional uplift is responsible for the river incision. Model exposure ages of deformed pediment surfaces along tributaries of the trunk stream range from 60 ± 5 ka to 110 ± 10 ka, demonstrating that the thrust faults responsible for pediment deformation were active after those times and were likely active earlier as well as explaining the topographic relief of the region. Together, our data demonstrate cumulative incision that is linked to active internal shortening and uplift of ~0.3 mm a-1 in the Central Pontide orogenic wedge, which may ultimately contribute to the lateral growth of the northern Anatolian Plateau.

  1. Characterizing and modeling the heterogeneity of fluvial reservoirs, a case study from Gypsy outcrop site, Pawnee County, Oklahoma

    SciTech Connect

    Jiang, R.; Forgotson, J.M. Jr.; O`Meara, D.J. Jr. [Univ. of Oklahoma, Norman, OK (United States)

    1996-12-31

    The genetic relationships between lithofacies and depositional environments and between lithofacies and permeability make the heterogeneity of fluvial reservoirs predictable and mappable. Two types of geological models (with/without lithofacies- dominated heterogeneity interpolation) have been simulated to illustrate the impact of geological modelling on predictions of oil recovery and sweep efficiency. Lithofacies, defined by certain types of constituents and sedimentary textures and structures, are responses to certain depositional flow regimes or local hydraulic conditions. The Gypsy outcrop site in Pawnee County, Oklahoma, which includes well exposed roadcuts with 22 cored boreholes behind the outcrop, provides a realistic three dimensional geological site and database for developing reservoir characterization techniques. Four lithofacies that control permeability are recognized at the Gypsy outcrop site. From bottom to top of a complete channel sequence, these are: (1) mudclast sandstones (low permeability); (2) sandstones dominated by cross beds and planar laminated sets (high permeability); (3) ripple and bioturbated sandstone (low permeability); (4) mudstone and millstone (flow barrier). The lithofacies within each channel were mapped based on the Gypsy outcrop and cored borehole data. These maps provided input to geological modelling software for 3-D visualization. A flow simulator was used to study models consisting of up to 500,000 grid cells.

  2. Characterizing and modeling the heterogeneity of fluvial reservoirs, a case study from Gypsy outcrop site, Pawnee County, Oklahoma

    SciTech Connect

    Jiang, R.; Forgotson, J.M. Jr.; O'Meara, D.J. Jr. (Univ. of Oklahoma, Norman, OK (United States))

    1996-01-01

    The genetic relationships between lithofacies and depositional environments and between lithofacies and permeability make the heterogeneity of fluvial reservoirs predictable and mappable. Two types of geological models (with/without lithofacies- dominated heterogeneity interpolation) have been simulated to illustrate the impact of geological modelling on predictions of oil recovery and sweep efficiency. Lithofacies, defined by certain types of constituents and sedimentary textures and structures, are responses to certain depositional flow regimes or local hydraulic conditions. The Gypsy outcrop site in Pawnee County, Oklahoma, which includes well exposed roadcuts with 22 cored boreholes behind the outcrop, provides a realistic three dimensional geological site and database for developing reservoir characterization techniques. Four lithofacies that control permeability are recognized at the Gypsy outcrop site. From bottom to top of a complete channel sequence, these are: (1) mudclast sandstones (low permeability); (2) sandstones dominated by cross beds and planar laminated sets (high permeability); (3) ripple and bioturbated sandstone (low permeability); (4) mudstone and millstone (flow barrier). The lithofacies within each channel were mapped based on the Gypsy outcrop and cored borehole data. These maps provided input to geological modelling software for 3-D visualization. A flow simulator was used to study models consisting of up to 500,000 grid cells.

  3. Dynamics of a mobile-meander-fluvial system in the tropical humid zone, the Rio Mamoré (Bolivian Amazonia)

    NASA Astrophysics Data System (ADS)

    Bourrel, L.; Charrière, M.; Gautier, E.; Guyot, J. L.

    2003-04-01

    The Rio Mamore, main river of the Bolivian Amazonia, develops highly mobile meanders which sweep the plain over an average width of 10 km. The band of migration is underlined by a dense forest gallery. The very large floodplain “Llanos de Mojos”, inundated more than four month a year, is partially occupied by these mobile meanders. The objective of this work is to establish a first morphodynamic sectorization of the Mamore river. The approach is based on an analysis of various morphodynamic variables, in both a synchronic and diachronic manner. Morphodynamic parameters were measured on satellital images, topographical maps and on-the-fields data. The variables were quantified and were the subject of statistical analysis (multivariate treatment of ACP type). The analysis make it possible to propose a sectorization of the river continuum in six functional sections. The role playing by main variables of control is underlined: the total sediment load and the valley slope constitute the fundamental independent variables, which contribute strongly to the spatial variability of the Mamoré river. Furthermore, on the basis of this characterization, the interrelations between the various morphometric parameters, that had been showed on temperate zone rivers, are readjusted for tropical humid fluvial systems. The coupling of the morphodynamic approach with the hydrological and sediment load data highlights a close connection: the lateral erosion rate mainly depends on the discharge duration close to the bank-full stage, while the cutting of the meanders is favoured by floods.

  4. The impact of glacial/interglacial climate changes on fluvial and mass-wasting processes in the Taiwan's mountains

    NASA Astrophysics Data System (ADS)

    Li, W. L.; Hsieh, M. L.; Tsui, H. K.; Hsiao, Y. T.

    2014-12-01

    The Taiwan orogenic belt, located in Southeastern Asia, is under monsoon climate, frequently attacked by tropical typhoons, and characterized by rapid tectonic uplift with high seismicity. Researchers have been linking the Taiwan's landscapes to active tectonic uplift. In this study, we show the significance of glacial/interglacial climate changes in shaping the landscapes. We focus on the mountain areas that have never been glaciated. Based on >400 radiocarbon dates (70 of which >12 ka), we find that both the slope and fluvial activities were generally low during the glacial time. Still, extensive alluviation had occurred at certain time periods, forming large debris slopes or alluvial fans (typically along mountain fronts), and causing significant aggradation along some major rivers. In contrast, with numerous landslides and debris flows, river incision has dominated during the postglacial time. Episodic river aggradation with alluvial-terrace development (typically at tributary mouths) also occurred during this time period, but was less extensive than previously. Some huge postglacial alluvial terraces have been proved sourced from the colluviums deposited in the glacial time. We attribute the low landscape activities of the glacial period to the dryness during the period. However, even in this time rare but severe rainfall events must have occurred to trigger some extensive alluviation. In contrast, the increase in both rainfall and typhoon frequency during the postglacial time drastically increased the slope instability and sediment yield. The great stream power, along with the sufficient coarse debris acting as erosion tools, ensured the rapid river incision during this time.

  5. Application of nonmarine genetic sequence stratigraphic concepts to reservoir characterization in the fluvial-lacustrine Westbourne Formation, Eromanga basin, Australia

    SciTech Connect

    Hamilton, D.S.; Holtz, M.H.; Yeh, J. (Univ. of Texas, Austin, TX (United States)) (and others)

    1996-01-01

    A high-resolution sequence stratigraphic analysis of the Westbourne Formation identified five chronostratigraphic genetic units each separated by thin, but laterally extensive, shale markers interpreted as maximum lacustrine flooding surfaces. The flooding surfaces were primarily identified by their lateral persistence and high gamma-ray log response, but marked changes in bedding architecture across these surfaces also facilitated their identification. The changes in bedding architecture reflect reorganization of the depositional systems from one depositional episode to the next. The Westbourne Formation is interpreted as a series of fluvially-dominated lacustrine delta sequences. Although the genetic units generally display lobate to digitate sand body geometries, sediment transport directions between successive units is highly variable. The complex morphology of the distributary network and accompanying high degree of facies variability indicates shallow lacustrine sedimentation similar to that in the modern inland Niger River delta which provides a modern analog. Westbourne fluid flow trends were established by mapping water encroachment during field development, observing differential depletion in repeat formation test data, and monitoring production response to water shut-off workovers. The fluid flow trends emphasized the highly layered character of the Westbourne reservoirs and integrating these trends with the geologic architecture defined stratigraphic controls on Westbourne flow units. The stratigraphic framework proved essential for unraveling sediment transport patterns and thus, predicting reservoir sandstone distribution. The stratigraphic framework also provided the key to understanding water encroachment and pressure a depletion which, when combined with predicted sandstone geometries, identified several step-out drilling and recompletion opportunities.

  6. A study of the relationship between permeability distributions and small scale sedimentary features in a fluvial formation

    SciTech Connect

    Gotkowitz, M.

    1993-10-01

    This study focuses on styles of small-scale heterogeneity found in fluvial sand and soil bodies. Over 1,700 in situ measurements of air permeability were taken in an outcrop-based study which joins observations of sedimentary features with their associated permeability distributions. The relationship between sedimentology and hydrologic parameters provides a geologic framework to assess geostatistical hypotheses. The soils in the study area are found to have a significantly lower permeability than the channel sand deposits. The soil deposits showed a significant lack of observable small scale sedimentary structures, which is reflected in the experimental variograms. The permeability distribution in these study sites appears to be adequately represented by a continuous gaussian random field model. The presence of calcium carbonate nodules in the soils is related to the permeability distribution. Correlation lengths in the channel sands perpendicular to stratigraphy are significantly shorter than those observed parallel to stratigraphy. A sedimentological, bounding surfaces model is evaluated with regard to permeability distributions. In deposits of little sedimentary structure, the mean and variance may adequately characterize the permeability distribution. Where significant sedimentary structure exists, the bounding surfaces model can be used to determine the scales of variability present in the permeability distribution and may also be used to infer an appropriate choice of random field model.

  7. Preservation of large titanosaur sauropods in overbank fluvial facies: A case study in the Cretaceous of Argentina

    NASA Astrophysics Data System (ADS)

    González Riga, Bernardo J.; Astini, Ricardo A.

    2007-04-01

    Patagonia exhibits a particularly abundant record of Cretaceous dinosaurs with worldwide relevance. Although paleontological studies are relatively numerous, few include taphonomic information about these faunas. This contribution provides the first detailed sedimentological and taphonomical analyses of a dinosaur bone quarry from northern Neuquén Basin. At Arroyo Seco (Mendoza Province, Argentina), a large parautochthonous/autochthonous accumulation of articulated and disarticulated bones that represent several sauropod individuals has been discovered. The fossil remains, assigned to Mendozasaurus neguyelap González Riga, correspond to a large (18-27-m long) sauropod titanosaur collected in the strata of the Río Neuquén Subgroup (late Turoronian-late Coniacian). A taphonomic viewpoint recognizes a two-fold division into biostratinomic and fossil-diagenetic processes. Biostratinomic processes include (1) subaerial biodegradation of sauropod carcasses on well-drained floodplains, (2) partial or total skeletal disarticulation, (3) reorientation of bones by sporadic overbank flows, and (4) subaerial weathering. Fossil-diagenetic processes include (1) plastic deformation of bones, (2) initial permineralization with hematite, (3) fracturing and brittle deformation due to lithostatic pressure; (4) secondary permineralization with calcite in vascular canals and fractures, and (5) postfossilization bone weathering. This type of bone concentration, also present in Rincón de los Sauces (northern Patagonia), suggests that overbank facies tended to accumulate large titanosaur bones. This taphonomic mode, referred to as "overbank bone assemblages", outlines the potential of crevasse splay facies as important sources of paleontological data in Cretaceous meandering fluvial systems.

  8. Fluvial dynamics of an anabranching river system in Himalayan foreland basin, Baghmati river, north Bihar plains, India

    NASA Astrophysics Data System (ADS)

    Jain, Vikrant; Sinha, R.

    2004-05-01

    Anabranching river systems are now regarded as a separate class in river classifications owing to their distinctive morphological/hydrological characteristics and fluvial processes. A better understanding of anabranching rivers still needs detailed data from different environmental and geographical settings. This paper presents a detailed account of an anabranching river system from the Himalayan foreland basin. The Baghmati river system from north Bihar Plains, eastern India provides a typical example of an anabranching river system located in the interfan area between the Kosi and the Gandak megafans. The river system is braided in upstream reaches and meandering in downstream reaches, but the midstream anabranching reach is characterized by low width-depth ratio (11-16), gentle gradient (0.00018-0.00015), variable peak discharge, frequent flooding and high sediment load. The anabranching in the midstream reaches is a response to its inability to transport high sediment load due to gentle channel slope and dominance of aggradation process. The development of anabranches is related to rapid and frequent avulsions of the river channels with eight major avulsions observed in the 30-km-wide floodplain in the last 230 years. The decadal scale avulsion history of the Baghmati river system makes it 'hyperavulsive' and the major causative factors for such channel instability are sedimentological readjustments and active tectonics in the basin area.

  9. Application of nonmarine genetic sequence stratigraphic concepts to reservoir characterization in the fluvial-lacustrine Westbourne Formation, Eromanga basin, Australia

    SciTech Connect

    Hamilton, D.S.; Holtz, M.H.; Yeh, J. [Univ. of Texas, Austin, TX (United States)] [and others

    1996-12-31

    A high-resolution sequence stratigraphic analysis of the Westbourne Formation identified five chronostratigraphic genetic units each separated by thin, but laterally extensive, shale markers interpreted as maximum lacustrine flooding surfaces. The flooding surfaces were primarily identified by their lateral persistence and high gamma-ray log response, but marked changes in bedding architecture across these surfaces also facilitated their identification. The changes in bedding architecture reflect reorganization of the depositional systems from one depositional episode to the next. The Westbourne Formation is interpreted as a series of fluvially-dominated lacustrine delta sequences. Although the genetic units generally display lobate to digitate sand body geometries, sediment transport directions between successive units is highly variable. The complex morphology of the distributary network and accompanying high degree of facies variability indicates shallow lacustrine sedimentation similar to that in the modern inland Niger River delta which provides a modern analog. Westbourne fluid flow trends were established by mapping water encroachment during field development, observing differential depletion in repeat formation test data, and monitoring production response to water shut-off workovers. The fluid flow trends emphasized the highly layered character of the Westbourne reservoirs and integrating these trends with the geologic architecture defined stratigraphic controls on Westbourne flow units. The stratigraphic framework proved essential for unraveling sediment transport patterns and thus, predicting reservoir sandstone distribution. The stratigraphic framework also provided the key to understanding water encroachment and pressure a depletion which, when combined with predicted sandstone geometries, identified several step-out drilling and recompletion opportunities.

  10. Paleoclimate cycles and tectonic controls on fluvial, lacustrine, and eolian strata in upper Triassic Chinle Formation, San Juan basin

    SciTech Connect

    Dubiel, R.F. (Geological Survey, Denver, CO (USA))

    1989-09-01

    Sedimentologic study of the Upper Triassic Chinle Formation in the San Juan basin (SJB) indicates that Late Triassic paleoclimate and tectonic movements influenced the distribution of continental lithofacies. The Shinarump, Monitor Butte, and Petrified Forest Members in the lower part of the Chinle consist of complexly interfingered fluvial, floodplain, marsh, and lacustrine rocks; the Owl Rock and Rock Point Members in the upper part consists of lacustrine-basin and eolian sandsheet strata. Facies analysis, vertebrate and invertebrate paleontology, and paleoclimate models demonstrate that the Late Triassic was dominated by tropical monsoonal circulation, which provided abundant precipitation interspersed with seasonally dry periods. Owl Rock lacustrine strata comprise laminated limestones that reflect seasonal monsoonal precipitation and larger scale, interbedded carbonates and fine-grained clastics that represent longer term, alternating wet and dry climatic cycles. Overlying Rock Point eolian sand-sheet and dune deposits indicate persistent alternating but drier climatic cyclicity. Within the Chinle, upward succession of lacustrine, alternating lacustrine/eolian sand-sheet, and eolian sand-sheet/dune deposits reflects an overall decrease in precipitation due to the northward migration of Pangaea out of low latitudes dominated by monsoonal circulation.

  11. Aptitud relativa agrícola del municipio de Tuxpan, Nayarit, utilizando el modelo Almagra del Sistema MicroLEIS

    Microsoft Academic Search

    José López García

    2006-01-01

    Agricultural land evaluation in the fluvial-marine plain within the municipality of Tuxpan, Nayarit, was carried out based onto a semi-detailed soil survey. Relative agricultural aptitude was evaluated, through out a modified Almagra's model of MicroLeis 4.1 system, defining a new model: the Almagra-Tuxpan, based on the specific conditions of the zone. Using the Almagra-Tuxpan model, a software routine was written

  12. Distribution pattern of metals in fluvial sediments in mountainous rural catchments: a case study in Northern Portugal

    NASA Astrophysics Data System (ADS)

    Reis, Anabela; Parker, Andrew; Alencoão, Ana

    2015-04-01

    The management of sediments-associated contaminants, concerning quality and quantity, in mountainous rivers is a pertinent issue; it is well known that mountainous rivers contribute with significant sedimentary loads, transported in short periods of time, in response to short precipitation episodes. Our contribution presents results of a research study developed in one of the tributaries of the River Douro, the River Corgo catchment (studied area of 295 km2). The River Corgo traverses Vila Real city and encounters the River Douro in Régua, in the West limit of the Douro Region - classified as UNESCO World Heritage. The altitudes vary between 200-1400m. The bedrock is composed of crystalline rocks and the land use is mainly forest and agriculture, with scattered urban settlements. The aim was to investigate the dynamics and availability of sediment contaminants in mountainous rural rivers, in a temperate climate. Active fluvial sediments (<63?m fraction) were studied with the aim of characterising the spatial and temporal distribution of the contents of Cd, Co, Cr, Ni, Cu, Zn, Pb, Fe and Mn, in the catchment. To assess possible different origins of metals (natural vs. anthropogenic), and potential availability, a sequential chemical approach was used (modified BCR procedure); the element concentrations were obtained by ICP-AES. The results suggest that Cr and Ni are the main metals from lithological source, with relatively higher contents in the residual fraction, and the lowest in the most mobile fractions. Copper, Zn and, in particular, Pb show higher concentrations in the most labile fractions, suggesting an important contribution of anthropogenic activities to the total contents in the sediments. The spatial distribution pattern of metal contents indicates higher contents of metals in the most mobile fractions occurring along the main courses of the major tributaries (in particular in the flatter reaches, where finer sediment preferentially accumulates). In sampling sites located in the vicinity of point pollution sources, there is an increase of sediment bound-metal contents, which indicates that even in more energetic streams the sediments are able to control, to a significant extent, the levels of metals in the fluvial water. Complementary studies to estimate the delivered quantities of eroded material and associated contaminants, with the aim to relate to the amount of sediments transported within the catchment, are being performed. A GIS based potential soil loss spatial index model was developed with assessment of sediment yield from different lithologies within the catchment. The results show that about 2% of the study area is classified as highest erosion risk potential, and 22% area is under low to moderate erosion risk; these locate in the west, northwest and southern regions of the study area. The estimated soil losses are related, essentially, with one lithology (48%).

  13. Long-term interactions between man and the fluvial environment - case of the Diyala alluvial fan, Iraq

    NASA Astrophysics Data System (ADS)

    Heyvaert, Vanessa M. A.; Walstra, Jan; Mortier, Clément

    2014-05-01

    The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, Tigris and their tributaries), which are prone to avulsions. An avulsion can be defined as the diversion of flow from an existing channel onto the floodplain, eventually resulting in a new channel belt. Early civilizations depended on the position of rivers for their economic survival and hence the impact of channel shifts could be devastating (Wilkinson 2003; Morozova 2005; Heyvaert & Baeteman 2008). Research in the Iranian deltaic part of the Mesopotamian plain has demonstrated that deliberate human action (such as the construction of irrigation canals and dams) triggered or obstructed the alluvial processes leading to an avulsion on fluvial megafans (during preconditioning, triggering and post-triggering stages) (Walstra et al. 2010; Heyvaert et al. 2012, Heyvaert et al.2013). Thus, there is ample evidence that the present-day alluvial landscapes in the region are the result of complex interactions between natural and anthropogenic processes. Here we present a reconstruction of the Late Holocene evolution of the Diyala alluvial fan (one of the main tributaries of the Tigris in Iraq), with particular attention to the relations between alluvial fan development, changes in channel pattern, the construction of irrigation networks and the rise and collapse of societies through historic times. The work largely draws on the use of remote sensing and GIS techniques for geomorphological mapping, and previously published archaeological field data (Adams 1965). By linking archaeological sites of known age with traces of ancient irrigation networks we were able to establish a chronological framework of alluvial activity of the Diyala alluvial fan. Our results demonstrate that centralized and technologically advanced societies were able to maintain a rapidly aggradading distibutary channel system, supplying water and sediment across the entire alluvial fan. As a consequence, during these periods (Parthian, Sasanian and again in modern times), significant human modification of the landscape took place. Periods of societal decline are associated with reduced human impact and the development of a single-threaded incising river system. Adams, R.M. (1965). Land behind Baghdad: A history of settlement on the Diyala plains. University of Chicago Press, Chicago, Illinois. Heyvaert, V.M.A. & Baeteman, C. (2008). A Middle to Late Holocene avulsion history of the Euphrates river: a case study from Tell ed-D-er, Iraq, Lower Mesopotamia. Quaternary Science Reviews, 27, 2401-2410. Heyvaert, V. M. A., Walstra, J., Verkinderen, P., Weerts, H. J. T. & Ooghe, B. (2012). The role of human interference on the channel shifting of the river Karkheh in the Lower Khuzestan plain (Mesopotamia, SW Iran). Quaternary International, 251, 52-63. Heyvaert, V.M.A., Walstra, J., Weerts, H.J.T. (2013). Human impact on avulsion and fan development in a semi-arid region: examples from SW Iran. Abstractbook of the 10th International Fluvial Sedimentology Conference, July 2013,Leeds, United Kingdom. Morozova, G.S. (2005). A review of Holocene avulsions of the Tigris and Euphrates rivers and possible effects on the evolution of civilizations in lower Mesopotamia. Geoarchaeology, 20, 401-423. Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. (2010). Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran). Geodinamica Acta, 23, 267-285. Wilkinson, T.J. (2003). Archaeological Landscapes of the Near East. The University of Arizona Press, Tucson, Arizona.

  14. Variations in fluvial style in the Westwater Canyon Member, Morrison formation (Jurassic), San Juan basin, Colorado plateau

    USGS Publications Warehouse

    Miall, A.D.; Turner-Peterson, C. E.

    1989-01-01

    Techniques of architectural element analysis and lateral profiling have been applied to the fluvial Westwater Canyon Member of the Morrison Formation (Jurassic) in southern San Juan Basin. On a large scale, the sandstone-body architecture consists mainly of a series of tabular sandstone sheets 5-15 m thick and hundreds of meters wide, separated by thin fine-grained units. Internally these sheets contain lateral accretion surfaces and are cut by channels 10-20 m deep and at least 250 m wide. On a more detailed scale, interpretations made from large-scale photomosaics show a complex of architectural elements and bounding surfaces. Typical indicators of moderate- to high-sinuosity channels (lateral accretion deposits) coexist in the same outcrop with downstream-accreted macroform deposits that are typical of sand flats of low-sinuosity, multiple-channel rivers. Broad, deep channels with gently to steeply dipping margins were mapped in several of the outcrops by carefully tracing major bounding surfaces. Locally thick accumulations of plane-laminated and low-angle cross-laminated sandstone lithofacies suggest rapid flow, probably transitional to upper flow regime conditions. Such a depositional style is most typical of ephemeral rivers or those periodically undergoing major seasonal (or more erratic) stage fluctuations, an interpretation consistent with independent mineralogical evidence of aridity. Fining-upward sequences are rare in the project area, contrary to the descriptions of Campbell (1976). The humid alluvial fan model of Galloway (1978) cannot be substantiated and, similarly, the architectural model of Campbell (1976) requires major revision. Comparisons with the depositional architecture of the large Indian rivers, such as the Ganges and Brahmaputra, still seem reasonable, as originally proposed by Campbell (1976), although there is now convincing evidence for aridity and for major stage fluctuations, which differs both from those modern rivers and Campbell's interpretation. ?? 1989.

  15. Facies and fluvial architecture of a high-energy braided river: the Upper Proterozoic Seglodden Member, Varanger Peninsula, northern Norway

    NASA Astrophysics Data System (ADS)

    Hjellbakk, Andor

    1997-12-01

    The Seglodden Member (Late Proterozoic), as studied in two areas of the Varanger Peninsula, northern Norway, is dominated by sand-rich braided river deposits. A quantitative summary of described facies emphasises the dominance of structures deposited under high-energy conditions, and a general absence of fine-grained deposits and visible small-scale sedimentary structures. The sigmoidal and concave-up cross-stratified, planar horizontally stratified and massive sandstone facies represent 80-95% of the total vertical thicknesses of the measured sections. Architectural elements are defined as 'sheet sandstone bodies' and 'channel forms and fills' and comprise simple bars, transitional simple bar-dune complexes, dune complexes, downstream accretion complexes and various types of channel deposits. The Seglodden fluvial system was operating in a non-vegetated setting with well exposed sediment sources, probably of a sedimentary origin. This situation gave a very erratic discharge system with rapid runoff, high denudation rate and very high sediment discharge. Increased flow within channels was compensated for by a broadening of the channels, and it is inferred that the channels were very wide and shallow relative to their depths. Bounding surfaces of at least six different orders (0th-5th) are interpreted within the studied successions, with the third-order surface as the lowest-order surface that bound architectural elements as defined in this study. The highest-order surface (5th order) is probably the result of channel belt switching due to a combination of sedimentary processes and tectonic subsidence of the basin. The east and northeasterly palaeocurrent trend in the Seglodden area compared to the southeasterly trend in the Smellror area indicates that the axis of the depositional system changed significantly in direction basinwards over the 15-20 km distance between the two study areas. The controlling mechanisms for this may be autocyclic as well as allocyclic processes, although the tectonic influence on sedimentation was probably significant.

  16. Laramide basin subsidence and fluvial architecture of the Fort Union and Wasatch Formations in the southern greater Green River basin

    SciTech Connect

    Johnson, P.L. (San Jose State Univ., CA (USA))

    1990-05-01

    The late Paleocene Fort Union Formation and early Eocene Wasatch Formation exposed around the Rock Springs uplift demonstrate subsidence variations in the southern greater Green River basin. Total unit thickness and distribution of channel sandstones within overbank deposits record differences in subsidence rate across the basin. On the west flank of the Rock springs uplift, west of the bounding fault, channels have close spacing and thickness is low. On the south flank within the uplift, the thickness values are intermediary but channels are very closely spaced. Away from the uplift on the southeast flank, the thickness is greatest and channels are very widely spaced. Paleocurrents indicate that rivers flowed southward across the central basin to an eastward-flowing axis trunk river at the southern end of the basin. Both the south and southeast flank area were within the basin axis, but the west flank areas was within the central basin. Thickness trends represent subsidence variations across the basin. Subsidence was slowest at the west flank area. On the south flank, subsidence was greater, and the highest subsidence rate was on the southeast flank. Generally, thickness indicates increasing subsidence toward the Uinta uplift, but the south flank area is an exception. Basin subsidence occurred by flexure of the lithosphere under a tectonic load from the Uinta uplift to the south. Thickened lithosphere at the Rock springs uplift bounding fault was resistant to flexure. Thus, on the south flank near the fault, subsidence was slower than on the southeast flank where the lithosphere was not thickened. The closely spaced fluvial architecture on the south flank resulted from a narrow basin axis flood plain. A narrow flood plain possibly resulted from the subsidence resistance of thickened lithosphere at the Rock Springs uplift bounding fault or from topographic expression of the uplift itself.

  17. The effects of sample scheduling and sample numbers on estimates of the annual fluxes of suspended sediment in fluvial systems

    USGS Publications Warehouse

    Horowitz, Arthur J.; Clarke, Robin T.; Merten, Gustavo Henrique

    2015-01-01

    Since the 1970s, there has been both continuing and growing interest in developing accurate estimates of the annual fluvial transport (fluxes and loads) of suspended sediment and sediment-associated chemical constituents. This study provides an evaluation of the effects of manual sample numbers (from 4 to 12?year?1) and sample scheduling (random-based, calendar-based and hydrology-based) on the precision, bias and accuracy of annual suspended sediment flux estimates. The evaluation is based on data from selected US Geological Survey daily suspended sediment stations in the USA and covers basins ranging in area from just over 900?km2 to nearly 2?million?km2 and annual suspended sediment fluxes ranging from about 4?Kt?year?1 to about 200?Mt?year?1. The results appear to indicate that there is a scale effect for random-based and calendar-based sampling schemes, with larger sample numbers required as basin size decreases. All the sampling schemes evaluated display some level of positive (overestimates) or negative (underestimates) bias. The study further indicates that hydrology-based sampling schemes are likely to generate the most accurate annual suspended sediment flux estimates with the fewest number of samples, regardless of basin size. This type of scheme seems most appropriate when the determination of suspended sediment concentrations, sediment-associated chemical concentrations, annual suspended sediment and annual suspended sediment-associated chemical fluxes only represent a few of the parameters of interest in multidisciplinary, multiparameter monitoring programmes. The results are just as applicable to the calibration of autosamplers/suspended sediment surrogates currently used to measure/estimate suspended sediment concentrations and ultimately, annual suspended sediment fluxes, because manual samples are required to adjust the sample data/measurements generated by these techniques so that they provide depth-integrated and cross-sectionally representative data. 

  18. Paleo-channel reconstruction and grain size variability in fluvial deposits, Ferron Sandstone, Notom Delta, Hanksville, Utah

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Proma; Bhattacharya, Janok P.; Khan, Shuhab D.

    2015-07-01

    Planform meanderbelt exposures display the evolution of the channel which leads to better understanding of three dimensional architecture of the fluvial deposit. Due to the paucity of extensive plan-view exposures in rock record, reconstruction of paleo channels from plan form exposures has been hardly studied. This study combines closely spaced paleocurrent and grain size data from plan-view exposures of point bar deposits in the delta plain deposits of the Cretaceous Ferron Sandstone near Hanksville, Utah, USA. Airborne Light Detection and Ranging (LiDAR) was used to create hillshade images in which numerous crescent shaped sandstone ridges were identified. These are dominated by unidirectional paleocurrent and thus they are interpreted as scroll bars associated with four distinct meander loops. The loops show a combination of growth by lateral expansion and downstream translation. Cross-cutting relationships allow us to decipher the order of loop formation. Paleocurrent directions closely follow the shape of individual scroll bars. Plan-view grain size distributions show a coarsening trend toward the bend apex on individual scroll bars. However, at the scale of an entire meander loop, this trend is less prominent. Paleohydraulic estimates show that these channels have low sinuosity (1.3-1.7) and have an average discharge ranging from 42.1 to 66.4 m3/s. Comparison with larger sandbodies in underlying valley systems suggests that the studied channels represent the upper delta plain distributary channels and indicate an overall backstep with respect to channels in the immediately underlying incised valley.

  19. Combining Two Filter Paper-Based Analytical Methods to Monitor Temporal Variations in Fluvial Suspended Solid Properties

    NASA Astrophysics Data System (ADS)

    Cooper, Richard; Rawlins, Barry; Leze, Bertrand; Krueger, Tobias; Hiscock, Kevin

    2013-04-01

    Many of the commonly used analytical techniques for assessing the properties of fluvial suspended solids are neither cost-effective nor time-efficient, making them prohibitive to long-term high-resolution monitoring. We propose a novel methodology utilising two types of spectroscopy which, when combined with automatic water samplers, can generate accurate, high-temporal resolution sediment property data, inexpensively and non-destructively, directly from sediment covered filter papers. A dual X-ray fluorescence spectroscopy (XRFS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) approach is developed to estimate concentrations for a range of elements (Al, Ca, Ce, Fe, K, Mg, Mn, Na, P, Si, Ti) and compounds (organic carbon, Aldithionate, Aloxalate, Fedithionate, and Feoxalate) within sediments trapped on quartz fibre filters at masses as low as 3 mg. Calibration models with small prediction errors are produced for a total of 16 elements and compounds for which the geochemical signal is demonstrated to be time stable enabling samples to be stored for several weeks prior to analysis. Spectral pre-processing methods are shown to enhance the reproducibility of results for some compounds, whilst corrections for sediment mass retention are derived, and the importance of filter paper selection and homogeneous sample preparation in minimising spectral interference are emphasized. The results presented here demonstrate the potential for a combined XRFS and DRIFTS analysis of sediment covered filter papers to be utilized under a range of in-stream hydrological conditions where there is an environmental requirement for high-resolution monitoring of suspended solid properties.

  20. Sedimentology and shale modeling of a sandstone-rich fluvial reservoir: Upper Statfjord Formation, Statfjord field, Northern North Sea

    SciTech Connect

    MacDonald, A.C. (Institute for Energy Technology, Kjeller (Norway) Statoil, Research Centre, Trodheim (Norway)); Halland, E.K. (Norwegian Petroleum Directorate, Stavanger (Norway))

    1993-06-01

    Sandstone-rich fluvial reservoirs of the upper part of the Statfjord Formation in Statfjord field, northern North Sea, include significant proportions of inter-stratified shale beds which complicate the production of oil under a high-pressure miscible gas flood. Flood-plain mudstones, characterized by pedogenic alteration, and finely laminated abandoned channel facies form the most important flow barriers. Mudstones deposited in flood plains are expected to have a greater lateral continuity than those deposited in abandoned channels. Fluctuations in allogenic factors such as base level and sediment-supply rates have led to a variable preservation of the mudstones. This combination of different facies types and fluctuating allogenic control has led to a complex barrier distribution within the reservoir which is difficult to describe using conventional mapping techniques. A procedure, based on two stochastic simulation techniques, has been adopted in order to model the complex barrier distribution. A two-dimensional Markov field model is used as an alternative to conventional shale mapping to describe the distribution of shale beds that are correlated between two or more wells. The model is based on probabilistic estimations of shale continuity between well pairs and allows the simulation of local channel incision through otherwise extensive shale beds. A marked-point process model is adopted to describe the distribution of smaller scale discontinuous barriers within the reservoir sand bodies. It is based on probabilistic estimations of shale dimensions defined using cumulative frequency distributions. The stochastic modeling procedure allows greater flexibility to include a variety of geological interpretations and assumptions in the heterogeneity model and the increased geological input results in more realistic models of communication between and vertical permeability within the reservoir sand bodies. 72 refs., 18 figs.

  1. Assessment of Late Quaternary folding and shortening of the Longmenshan fold-and-thrust system (SE China) using fluvial terraces

    NASA Astrophysics Data System (ADS)

    Ding, R.

    2012-12-01

    Determining the magnitude of late Quaternary foreland deformation along the Longmenshan is relevant to assessing its role in regional crustal deformation. The Longmenshan foreland fold-and-thrust system mainly consists of a blind frontal fault zone, the Pujiang-Xinjin anticline, and the Longquanshan anticline. Surface deformation occurs mainly by folding, as well as some surface rupture, linked to the main Longmenshan fault zone through the deep detachment fault. The 2008 Wenchuan Ms 8.0 earthquake occurred along the front and central faults of Longmenshan fault zone. Fluvial landforms are very sensitive to tectonic activity. Quantitative analysis of warped terraces is an effective method for reconstructing the Late Quaternary growth of folds. The Minjiang River crosses the entire foreland thrust-fold system after flowing out of the Longmenshan fault zone. Using remote sensing image and digital elevation model interpretation, we conducted geomorphological and Quaternary sedimentation analyses along the middle part of the Minjiang River. Accurate measurements of river terraces using GPS, along with quaternary geochronology (OSL, AMS-14C, et al), permit reconstructing Minjiang River terraces sequence and longitudinal profile of the terraces to assess Late Quaternary surface deformation. Results suggest that: (1) The Wenchuan-Maowen fault activity predominately in the horizontal direction, with a minute vertical component; (2) The main vertical displacement of the Longmenshan fault zone occurs in Yingxiu-Beichuan fault;(3) The vertical deformation of frontal fault and the frontal buried fault is weak;(4) The Pujiang-Xinjin fault is more active which affected the formation of the T1 terrace;(5) The activity Longquanshan fault is weak, it is relatively stable since T3 formed.

  2. Evaluating fluvial terrace riser degradation using LiDAR-derived topography: An example from the northern Tian Shan, China

    NASA Astrophysics Data System (ADS)

    Wei, Zhanyu; Arrowsmith, J. Ramon; He, Honglin

    2015-06-01

    The morphological degradation of fluvial terrace risers provides a constraint to terrace chronology. In this study, we morphologically date the terrace risers along the Kuitun River on the north flank of the Tian Shan, China and subsequently discuss possible relationships between terrace formation and the past regional climate changes and tectonic activity of the Dushanzi fault-related fold. To do this, 159 topographic profile swaths of terrace risers were extracted from LiDAR-derived DEM and were analysed to determine a range of best fitting morphological ages. Through Monte Carlo simulation, a locally applicable sediment transport coefficient (diffusivity) was calibrated as 5.5 ± 1.6 m2/ky given the morphological age of the T1/T2 riser and its independently known age. Taking this calibrated coefficient, we estimate age ranges of 11.6 ± 3.4 ka, 6.5 ± 1.4 ka, 5.3 ± 1.1 ka, and 4.2 ± 1.2 ka for terraces T3, T4, T5, and T6, respectively, under the assumption that the age of the riser is close to the abandonment age of the lower surface. These new terrace ages, combining climate proxy records from the oxygen isotope curve from the Guliya ice cap and paleoearthquake events in the Dushanzi fault related fold, suggest that tectonic activity may be an important factor in the formation of lower terraces within the growing anticlines, while in more extensive areas beyond anticlines, climate changes controlled the main deposition and incision events in the present study area, and thus terrace formation of T1-T3.

  3. Change in dust and fluvial deposition variability in the Peruvian central continental coast during the last millennium: Response of the ocean atmospheric systems.

    NASA Astrophysics Data System (ADS)

    Sifeddine, A.; Briceño, F. J., Sr.; Caquineau, S.; Velazco, F.; Salvatecci, R.; Ortlieb, L.; Gutierrez, D.; Cardich, J.; Almeida, C.

    2014-12-01

    The particles from aeolian or fluvial origin are a useful proxy for the reconstruction of atmospheric condition patterns in the past. Changes in continental aridity and the atmospheric condition determine the composition and amount of lithogenic material and the way of transport from the continent. Here we present a record of laminated sediments (core B040506) retrieved in the continental shelf off Peru. Wind long-term suspension (regional) and local aeolian transport during the last millennium (transition from Medieval Climate Anomaly (MCA) to Little Ice Age (LIA) and the current warm period (CWP)) at centennial to decadal resolution are characterized. The particle provenance and grain size components are discussed using a mathematical model of fractionation. This model assumes that lithological composition of the sediment is an assemblage of several log-normally distributed particle populations. In this way, an interactive least square fitting routine is used to fit the particle grain size collected with the mathematical expression. This allows inferring the spatial and temporal variation of particle populations and thus the transport mechanisms involved. Our results showed a decrease in aeolian transport from the MCA - LIA transition and during the LIA with except of the local aeolian transport that shows peaks during the LIA. This decrease during LIA is accompanied by an enhanced fluvial transport. During the CWP the aeolian transport (Paracas dust storm and wind long-term suspension) display a high variability and tendency to increase in detriment of runoff. Comparison with other South American records indicates that those changes are linked to change in the shift of the ITCZ and Pacific high at the centennial time resolution. Finally the great increase of the fluvial transport within the transition of the LIA to the CWP is synchronous to severe drought period recorded in the Indo-Pacific region indicating higher frequency of El Niño events. Hence these factors indicate an unambiguous change in the atmospheric regime in relationship with climate changes in the last millennium over the Peruvian continental shelf.

  4. U.S. Geological Survey approved inorganic and organic methods for the analysis of water and fluvial sediment, 1954-94

    USGS Publications Warehouse

    Fishman, Marvin J.; Raese, Jon W.; Gerlitz, Carol N.; Husband, Richard A.

    1994-01-01

    All inorganic and organic methods for analyzing samples of water and fluvial sediment, which have been approved for use by the U.S. Geological Survey from 1954 to the present (1994), are listed. Descriptive method names include references to published reports for easy retrieval of methodology. The year each method was approved is listed as well as the year the method was discontinued. Inorganic and organic methods are listed separately by sample type (dissolved, whole water, bottom material, suspended sediment, or fish tissue) and by mode of analysis (manual or automated, or both).

  5. The influence of impurities in Titan ice bedrock on tensile strength and resistance to fluvial erosion: experimental results

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Images of the surface of Titan returned by the Cassini-Huygens mission show extensive fluvial drainage networks, which may be eroded by low-velocity impacts by ice clasts moving as bedload in rivers of liquid methane. Recent work has shown that the strength of polycrystalline water ice at Titan surface temperature of 93K is comparable to moderate strength rocks on Earth, and is significantly stronger than ice at terrestrial temperatures. However, the ice bedrock on Titan is likely to contain impurities such as silicates, atmospherically-derived hydrocarbon polymers and compounds of cryovolcanic origin. In this laboratory investigation, we examine the dependence of ice erosion resistance on the concentration of impurities, across a wide range of temperatures. The polycrystalline ice is made from a log-normally distributed seed crystal material with a median size of 1.4mm, which we combine with particles of basalt, ammonium-sulfate, and a urea polymer. We use the Brazilian tensile splitting test to measure the strength of the ice as a function of the concentration of each impurity. We erode 57-cm diameter drums of ice by repeatedly dropping a clast of known mass from a constant height and measure volume eroded with a topographic scanning technique where photographs are taken at an oblique angle to a vertically-oriented laser sheet. We control the temperature of the ice with dry ice and liquid nitrogen, as well as by conducting experiments in a walk-in freezer. The strength tests indicate that the ice strengthens with decreasing temperature and increasing concentration of impurity, for all impurity types. Additionally, the grain size of the added impurities is a strongly influences ice strength. The results of the erosion tests indicate that ice, regardless of composition, becomes stronger, and becomes more resistant to erosion, as it gets colder. However, the ice containing impurities is more resistant to erosion as compared to pure ice. Combining the results of both the strength tests and erosion experiments, we conclude that the resistance to erosion of the ice increases with increasing concentration of each impurity. These results will help constrain estimates of ice resistance to erosion, and possible erosion rates, that may occur on Titan and other icy satellites.

  6. Biotic drivers of fluvial sediment transport: Aggregate effects of sediment mobilisation by crayfish on catchment-scale sediment yield

    NASA Astrophysics Data System (ADS)

    Rice, Stephen; Mathers, Kate; Reeds, Jake; Extence, Chris

    2015-04-01

    Small but prolific organisms may be significant zoogeomorphic agents that make cumulative contributions to the large-scale terrestrial sediment cascade in, as yet, unknown and unquantified ways. One such organism is the signal crayfish (Pacifastacus leniusculus), which has invaded many European rivers. The geographical extent and abundance of this animal ensure innumerable local, small-scale interactions with the fluvial sediment system that have the potential to yield a substantial effect when aggregated across larger spatial and temporal scales. Here we estimate, for the first time, the proportion of the total annual sediment yield associated with crayfish activity in an infested river and examine the variability in crayfish-driven sediment flux integrated across daily, monthly and seasonal time scales. We focused on one of several mechanisms by which crayfish activities affect sediment dynamics: the mobilisation of fine sediments by foraging, fighting and burrowing under hydraulic conditions that are otherwise insufficient to entrain sediment. On the Brampton Branch of the River Nene, UK, a 12-month record of suspended sediment concentration (derived from a calibration of turbidity data against measured SSC) allowed calculation of sediment fluxes and integrated sediment loads at ten-minute intervals. Concurrent measurements of water depth and crayfish movements (using PIT tagging) confirmed that night-time crayfish activity was often associated with increased sediment fluxes in the absence of any change in hydraulic conditions. Sediment loads calculated for these periods of crayfish activity were compared with total loads to estimate the contribution made to sediment mobilisation by crayfish. Crayfish-induced fluxes were most significant during summer low-flows, becoming less important during winter when the crayfish were inactive and competent high flows dominated sediment transport. Nevertheless, the seasonal cumulative effect of crayfish was substantial and implies that crayfish can be important drivers of sediment movement in infested rivers. Moreover, observations suggest that a large proportion of the sediment available for transport during winter floods is introduced by bank retreat caused by crayfish burrowing. This implies that the total effect of crayfish on sediment yield is substantially greater than estimates based on entrainment effects alone.

  7. IDAHO FLUVIAL GEOLOGY

    EPA Science Inventory

    Restricted availability. Major Attributes: Polygons described by geologic type codes & descriptions. May be incorporated into maps at the state/county/basin scale. Probably too coarse for use at the site scale. Scale: 1:500:000. Extent: Idaho. Projection: Albers. Source: ...

  8. Hydrology & Fluvial Geomorphology

    E-print Network

    moisture, comprising 75% of worlds fresh water · Ground water: 0.5% of total · Surface Water: 0.2% · Soil · Infiltration function of: ­ vegetative cover ­ soil permeability & porosity ­ angle of slope ­ moisture content Moisture: 0.1% · Atmospheric Moisture: 0.0001% · Biological Water: negligible Hydrological Interactions 1

  9. Thermal Fluid and Fault Interactions at the Intersection of Two Faults, Agua Caliente, California

    NASA Astrophysics Data System (ADS)

    Wood, R. E.; Evans, J. P.

    2011-12-01

    Agua Caliente Springs lies at a unique intersection between the NNW-trending Elsinore fault and the 40° northeast-dipping, likely inactive West Salton detachment fault; it provides an opportunity to study damage zone geometry, fault behavior in crystalline rocks, a left-stepover zone between the Julian and Coyote segments, microseismicity, and the influence of thermal fluids on rock deformation. The Elsinore fault bounds the northwestern flank of the Tierra Blanca Mountains with strike-slip and normal motion; the detachment fault wraps around the northernmost portion of the mountains. Damage along the Elsinore ranges in thickness from a narrow slip plane to > 100 m along the eastern flank of the Tierra Blanca Mountains. Subsidiary faults trend northeast and southeast, and slip orientations vary from normal to strike-slip horizontal motion. Thermal fluids (~30°C) emerge at the intersection of the West Salton detachment and Elsinore faults actively alter the 94 Ma La Posta tonalite pluton, already fractured and crushed during fault slip, to a fine-grained white to orange powder through mineral re-equilibration. Grain sizes decrease with closer proximity to the faults. Fault cores contain thin dark green zones of chlorite ± epidote, and fault surfaces are coated with a thin layer of the same. Origin of the mineralization may be from reworked biotite crystals. We present water chemistry data from the hot springs at Agua Caliente in conjunction with geochemical and petrographic analysis of the surrounding rock. Water analyses include cation and anion measurements, bicarbonate, stable isotopes, tritium, and a multi-month recording of spring conductivity, water level, and temperature fluctuations. Cation geothermometry shows the fluids are enriched in Na, Ca, Mg, K, and Si from broken down quartz, plagioclase, and orthoclase. Water level and temperature data are compared to seismicity during the logging interval; temperatures so far have diurnal fluctuations indicating air temperature plays a larger role than anticipated for the subsurface fluids. Conductivity also displays daily cycles. We propose a larger scale map of the intersection of the two faults and the continuation of the Elsinore farther south showing the current extent and probable growth of the damage and alteration as more slip occurs. Spring flow increases post seismic events, and we believe by monitoring fluid chemistry and comparing seismicity along the faults we will see precursors to and effects from fault motion.

  10. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio Fluvial-Deltaic Sandstone Reservoirs of South Texas

    SciTech Connect

    McRae, L.E.; Holtz, M.H.; Knox, P.R.

    1995-07-01

    The Frio Fluvial-Deltaic Sandstone Play of South Texas is one example of a mature play where reservoirs are being abandoned at high rates, potentially leaving behind significant unrecovered resources in untapped and incompletely drained reservoirs. Nearly 1 billion barrels of oil have been produced from Frio reservoirs since the 1940`s, yet more than 1.6 BSTB of unrecovered mobile oil is estimated to remain in the play. Frio reservoirs of the South Texas Gulf Coast are being studied to better characterize interwell stratigraphic heterogeneity in fluvial-deltaic depositional systems and determine controls on locations and volumes of unrecovered oil. Engineering data from fields throughout the play trend were evaluated to characterize variability exhibited by these heterogeneous reservoirs and were used as the basis for resource calculations to demonstrate a large additional oil potential remaining within the play. Study areas within two separate fields have been selected in which to apply advanced reservoir characterization techniques. Stratigraphic log correlations, reservoir mapping, core analyses, and evaluation of production data from each field study area have been used to characterize reservoir variability present within a single field. Differences in sandstone depositional styles and production behavior were assessed to identify zones with significant stratigraphic heterogeneity and a high potential for containing unproduced oil. Detailed studies of selected reservoir zones within these two fields are currently in progress.

  11. Paleosols in the Upper Guantao Formation (Miocene) of the Gudong oil field and their application to the correlation of fluvial deposits

    SciTech Connect

    Liangmiao Ye [Research Institute of Petroleum Exploration and Development, Beijing (China)

    1995-07-01

    The main pay zone of the Upper Guantao Formation of the Gudong oil field, North China basin, is a 300-m-thick fluvial sequence. Due to lack of bio- and lithostratigraphic markers, correlation of the main pay zone has been difficult, especially in the beginning of the oil-field development. However, paleosols are well developed in this fluvial sequence. Core investigation indicates that the paleosols can be identified by a set of characteristics including color of sediment, original plant roots, caliche nodules, sedimentary structures, distribution of facies, and mineral composition. Log responses of paleosols include lower gamma-ray activity and higher sonic {Delta}t value, relative to non-paleosol sediments. An analysis of the evolution of paleosols and controlling geological factors illustrates that paleosols present time-stratigraphic markers and can be used to solve correlation problems. A stratigraphic framework, in which the Upper Guantao Formation was divided into three paleosol sets and two nonpaleosol sets, was built using paleosols as correlation markers. The results prove that the paleosol method of correlation is viable and very helpful for geological study of similar oil fields in the early evaluation and development design phase.

  12. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly report, July 1--September 30, 1997

    SciTech Connect

    Allison, M.L.

    1997-11-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Two activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone: (1) evaluation of the Ivie Creek and Willow Springs Wash case-study areas and (2) technology transfer.

  13. Complex fluvial response to low gradients at maximum regression: A genetic link between smooth sequence-boundary morphology and architecture of overlying sheet sandstone

    SciTech Connect

    Holbrook, J.M. [Southeast Missouri State Univ., Cape Girardeau, MO (United States). Dept. of Geosciences

    1996-07-01

    The Mesa Rica Sandstone is an extensive fluvial sandstone sheet that is separated from underlying marine strata throughout northeastern New Mexico by a regionally smooth and laterally continuous sequence-bounding unconformity. The Mesa Rica Sandstone consists mostly of channel-fill elements, with lesser proportions of lateral-accretion elements, and almost everywhere is of the same thickness as the largest channel fills. This broad sandstone sheet reflects deposition on a coastal plain by frequent avulsion and minor lateral migration of straight and low-sinuosity streams under nearly stable base-level conditions, which are here attributed to rapid progradation of the adjacent Mesa Rica deltaic shoreline relative to change in relative sea level during maximum Kiowa-Skull Creek regression. The Mesa Rica Sandstone and the sequence boundary that underlies it represent a distinctive genetic association of single-story fluvial sheet sandstone and smooth sequence-boundary morphology that is probably not unique to the Lower Cretaceous of northeastern New Mexico. Such unincised sequence boundaries are also implied in conceptual models and flume experiments of previous authors.

  14. Late Holocene chronology and geomorphic development of fluvial-tidal floodplains in the upper reaches of the lower Columbia River Valley, Washington and Oregon, USA

    NASA Astrophysics Data System (ADS)

    Peterson, Curt D.; Roberts, Michael C.; Vanderburgh, Sandy; Minor, Rick; Percy, David

    2014-01-01

    The upper reaches of the lower Columbia River Valley (125 km in length) comprise an alluvial system that is transitional between fluvial and fluvial-tidal dominance. Sinuous channels separate elongate islands (1-8 km in length) and floodplains (0.5-12.7 km in total width). Thirty-six floodplain overbank deposits are analyzed for age and depth, which demonstrate an average sedimentation rate of 1.6 m ka- 1 during the last 5-6 ka. Older core records confirm that long-term depositional rates are controlled by relative sea level rise. Rising floodplain groundwater surfaces, which followed relative sea level rise (~ 1.25 m ka- 1), submerged isolated floodplain depressions. Low sedimentation rates in the isolated depressions (0.6-1.1 m ka- 1) maintained large ellipsoidal bullseye lakes (7-22 km2 in area) dating back to 3.5-4.0 ka. Increases in the widths of the floodplains and bullseye lakes are associated with broadening of the incised valley (4-13 km width) in the Portland Basin. Dated basal overbank deposits (0.5-5.0 ka in age) and their separation distances establish channel migration rates of 0.3-1.9 km ka- 1. Shallow burial rates relative to rapid channel migration rates resulted in reworking of late Holocene floodplains (50-75% erosion) since 5 ka in the upper reaches of the lower Columbia River Valley.

  15. Data mining of external and internal forcing of fluvial systems for catchment management: A case study on the Red River (Song Hong), Vietnam

    NASA Astrophysics Data System (ADS)

    Schmitt, Rafael; Bizzi, Simone; Castelletti, Andrea

    2013-04-01

    The understanding of river hydromorphological processes has been recognized in the last decades as a priority of modern catchment management, since interactions of natural and anthropogenic forces within the catchment drives fluvial geomorphic processes, which shape physical habitat, affect river infrastructures and influence freshwater ecological processes. The characterization of river hydromorphological features is commonly location and time specific and highly resource demanding. Therefore, its routine application at regional or national scales and the assessment of spatio-temporal changes as reaction to internal and external disturbances is rarely feasible at present. Information ranging from recently available high-resolution remote-sensing data (such as DEM), historic data such as land use maps or aerial photographs and monitoring networks of flow and rainfall, open up novel and promising capacity for basin-wide understanding of dominant hydromorphological drivers. Analysing the resulting multiparametric data sets in their temporal and spatial dimensions requires sophisticated data mining tools to exploit the potential of this information. We propose a novel framework that allows for the quantitative assessment of multiparametric data sets to identify classes of channel reaches characterized by similar geomorphic drivers using remote-sensing data and monitoring networks available in the catchment. This generic framework was applied to the Red River (Song Hong) basin, the second largest basin (87,800 sq.km) in Vietnam. Besides its economic importance, the river is experiencing severe river bed incisions due to recent construction of new dams in the upstream part of the catchment and sand mining in the surrounding of the capital city Hanoi. In this context, characterized by an high development rate, current efforts to increase water productivity and minimize impacts on the fluvial systems by means of focused infrastructure and management measures require a thorough understanding of the fluvial system and, in particular, basin-wide assessment of resilience to human-induced change. . The framework proposed has allowed producing high-dimensional samples of spatially distributed geomorphic drivers at catchment scale while integrating recent and historic point records for the Red River basin. This novel dataset has been then analysed using self-organizing maps (SOM) an artificial neural network model in combination with fuzzy clustering. The above framework is able to identify non-trivial correlations in driving forces and to derive a fuzzy classification at reach scale which represents continuities and discontinuities in the river systems. The use of the above framework allowed analyzing the spatial distribution of geomorphic features at catchment scale, revealing patterns of similarities and dissimilarities within the catchment and allowing a classification of river reaches characterized by similar geomorphic drivers, fluvial processes and response to external forcing. The paper proposes an innovative and promising technique to produce hydromorphological classifications at catchment scale integrating historical and recent available high resolution data. The framework aims at opening the way to a more structured organization and analyses of recently available information on river geomorphic features, so far often missing or rarely exploited. This approach poses the basis to produce efficient databases of river geomorphic features and processes related to natural and anthropogenic drivers. That is a necessity in order to enhance our understanding of the internal and external forces which drive fluvial systems, to assess the resilience and dynamic of river landscapes and to develop the more efficient river management strategies of the future.

  16. An Assessment of Hydrology, Fluvial Geomorphology, and Stream Ecology in the Cardwell Branch Watershed, Nebraska, 2003-04

    USGS Publications Warehouse

    Rus, David L.; Dietsch, Benjamin J.; Woodward, Brenda K.; Fry, Beth E.; Wilson, Richard C.

    2007-01-01

    An assessment of the 16.3-square-mile Cardwell Branch watershed characterized the hydrology, fluvial geomorphology, and stream ecology in 2003-04. The study - performed by the U.S. Geological Survey in cooperation with the City of Lincoln, Nebraska, and the Lower Platte South Natural Resources District - focused on the 7.7-square-mile drainage downstream from Yankee Hill Reservoir. Hydrologic and hydraulic models were developed using the Hydrologic Modeling System (HEC-HMS) and River Analysis System (HEC-RAS) of the U.S. Army Corps of Engineers Hydraulic Engineering Center. Estimates of streamflow and water-surface elevation were simulated for 24-hour-duration design rainstorms ranging from a 50-percent frequency to a 0.2-percent frequency. An initial HEC-HMS model was developed using the standardized parameter estimation techniques associated with the Soil Conservation Service curve number technique. An adjusted HEC-HMS model also was developed in which parameters were adjusted in order for the model output to better correspond to peak streamflows estimated from regional regression equations. Comparisons of peak streamflow from the two HEC-HMS models indicate that the initial HEC-HMS model may better agree with the regional regression equations for higher frequency storms, and the adjusted HEC-HMS model may perform more closely to regional regression equations for larger, rarer events. However, a lack of observed streamflow data, coupled with conflicting results from regional regression equations and local high-water marks, introduced considerable uncertainty into the model simulations. Using the HEC-RAS model to estimate water-surface elevations associated with the peak streamflow, the adjusted HEC-HMS model produced average increases in water-surface elevation of 0.2, 1.1, and 1.4 feet for the 50-, 1-, and 0.2-percent-frequency rainstorms, respectively, when compared to the initial HEC-HMS model. Cross-sectional surveys and field assessments conducted between November 2003 and March 2004 indicated that Cardwell Branch and its unnamed tributary appear to be undergoing incision (the process of downcutting) (with three locations showing 2 or more feet of streambed incision since 1978) that is somewhat moderated by the presence of grade controls and vegetation along the channel profile. Although streambank failures were commonly observed, 96 percent of the surveyed cross sections were classified as stable by planar and rotational failure analysis-a disconnect that may have been the result of assumed soil properties. Two process-based classification systems each indicated that the reaches within the study area were incising and widening, and the Rosgen classification system characterized the streams as either type E6 or B6c. E6 channels are hydraulically efficient with low width-depth ratios, low to moderate sinuosity, and gentle to moderately steep slopes. B6c channels typically are incised with low width-depth ratios maintained by riparian vegetation, low bedload transport, and high washload transport. No obvious nickpoints (interruption or break in slope) were observed in the thalweg profile (line of maximum streambed descent), and the most acute incision occurred immediately downstream from bridges and culverts. Nine water-quality samples were collected between August 2003 and November 2004 near the mouth of the watershed. Sediment-laden rainfall-runoff substantially affected the water quality in Cardwell Branch, leading to greater biochemical and chemical oxygen demands as well as increased concentrations of several nutrient, bacteriological, sediment, and pesticide constituents. The storage of rainfall runoff in Yankee Hill Reservoir may prolong the presence of runoff-related constituents downstream. Across the study area, there was a lack of habitat availability for aquatic biota because of low dissolved oxygen levels and low streamflows or dry channels. In August 2003, the aquatic community near the mouth of

  17. Vegetation development following stream/river restoration: more natural fluvial dynamics and morphology, return of aquatic and riparian plant species?

    NASA Astrophysics Data System (ADS)

    Soons, M. B.

    2012-04-01

    After centuries of human interventions in stream/river dynamics and morphology aimed at optimizing landscapes for agricultural and industrial purposes, new insights have inspired water managers to try and combine stream and river ecosystem functions with the conservation of biodiversity. Around the world, aquatic and riparian species have declined strongly due to pollution, destruction and fragmentation of their habitat, so that biodiversity conservation initiatives primarily focus on habitat restoration. In the past decades many stream and river restoration projects have been carried out and often hydrological dynamics and morphology have been restored to a more natural state. However, the successful restoration of aquatic and riparian habitats very often failed to result in restoration of their biodiversity. This lack of success from a biodiversity conservation perspective is usually attributed to 'dispersal limitation', meaning that the habitat may be restored, but species fail to reach the site and re-colonize it. Especially re-colonization by aquatic and riparian plant species is important, as such species function as ecosystem engineers: their presence alters fluvial dynamics and morphology, generates additional habitat heterogeneity and provides habitat and food for animal species. Following minor disturbances, re-colonization is often possible through locally remaining populations, by seeds in the seed bank or by surviving plant fragments. However, following major disturbances, colonization and establishment from other source populations are necessary. This usually occurs through dispersal of seeds (and in more aquatic species also by dispersal of vegetative fragments) into the restored wetland area. As dispersal occurs predominantly over short distances and source populations of aquatic and riparian species may be lacking in the surroundings, dispersal may be a limiting factor in the development of aquatic and riparian vegetation at a restored site. But, even if seeds have successfully dispersed into an area, local germination and establishment may also be limiting for the development of local biodiversity and/or for restoration success. However, we know surprisingly little about the crucial process of colonization. This presentation focusses on colonization by aquatic and riparian plant species. I combine the results of several studies investigating dispersal, germination and establishment. A study on restored riparian zones along mountain streams shows that several years after restoration, the species composition at the restored sites shows signs of dispersal limitation: species with nearby source populations re-colonized successfully, but species without source populations in the immediate surroundings often remained absent. A detailed study on the re-colonization of a restored riparian zone along a lowland stream reveals that many species enter the site as seeds, but relatively few of these seeds are able to germinate and establish successfully, indicating that both a strong dispersal filter and a strong environmental filter control local vegetation development and hence stream dynamics and morphological developments. While the intensity of the disturbance of local conditions has a great impact on the role of the environmental filter, dispersal clearly remains a limiting factor in many situations.

  18. Landscape Response to Glacial-Interglacial Climate Forcing From Fluvial Fill Terraces: Humahuaca Basin, E Cordillera, NW Argentina

    NASA Astrophysics Data System (ADS)

    Schildgen, Taylor; Robinson, Ruth; Savi, Sara; Bookhagen, Bodo; Tofelde, Stefanie; Strecker, Manfred

    2015-04-01

    Fluvial fill terraces record changes in sediment production and/or transport in response to external forcing. Worldwide, climate shifts associated with glacial-interglacial cycles have often been linked to fill terrace formation, making them promising features for recording landscape responses to millennial-scale climate changes. Within the southern Central Andes, glacial intervals are marked by pronounced increases in rainfall, which in some places have been correlated with increased landslide activity. The N-S oriented, semi-arid Humahuaca intermontane basin parallels the eastern margin of the Andean Plateau (Puna) and is known for frequent landslides and debris flows during the wet season. Fill terraces along tributaries (20-1100 km2 catchments) to the trunk stream have been dated with OSL to between ~30 and 120 ka. Curiously, aggradation phases in terraces on the west side of the basin correlate with past wet periods, while those on the east side correlate with past dry periods. While yearly rainfall and lithology on either side of the basin are similar, the tributary geometries are different: the east side tributaries contain perched sedimentary basins that are separated from the main valley by narrow bedrock gorges, while the west side tributaries have a relatively simple form, without perched basins or prominent gorges. From modern sediments exiting the tributaries, denudation rates calculated from cosmogenic nuclide (10Be) concentrations of pebbles (1-3 cm) are 1.2 to 4x higher than those derived from sand (< 0.7 cm), which could reflect the importance of mass movements today. From terraces on the west side of the valley (wet-phase terraces), denudation rates are higher than those from modern streams, with strong grain-size dependence and very high scatter, which may reflect an even greater importance of mass movements during past wetter periods. In contrast, from terraces on the east side of the valley (dry-phase terraces), pebble and sand denudation rates overlap with modern rates. We interpret the data to imply that landslides are triggered throughout the landscape during wet phases and induce aggradation, but along the eastern side of the valley, landslides block the narrow gorges between the headwaters and the outlets, causing sediment to remain within the perched basins. In contrast, during drier phases with reduced landslide frequency, clearing of landslide blockages and slow re-excavation of stored sediments from the perched basins leads to increased 10Be concentrations in the sediment and sediment delivery to the main valley. Overall, while landslides appear to be triggered throughout the landscape during wetter climate phases, the valley geometry dictates when sediment is evacuated from the tributary valleys into the main valley. Such behavior at an orogen-scale could attenuate or mask landscape responses to climate forcing in older sedimentary archives.

  19. Morphometric analysis of drainage network in the northern sector of the southern Italian foredeep: implications for fluvial denudation processes and Late Quaternary geomorphological evolution

    NASA Astrophysics Data System (ADS)

    Gioia, D.; Moretti, M.; Gallicchio, S.; Schiattarella, M.

    2012-04-01

    We present new data about the morphological and stratigraphic evolution and the rates of fluvial denudation of an area located in the northernmost sector of the foredeep of the southern Apennines. The study area is the medium- to low-relief sector located between the easternmost part of the Daunia Apennine and the Apulian foreland of the Gargano promontory. This area is characterized by several orders of terraced fluvial deposits disconformably overlying lower Pleistocene marine clay and organized in a staircase geometry, which recorded the emersion and the long-term incision history of this sector since mid-Pleistocene times. Geomorphological analyses have been carried out in order to retrace the landscape evolution of the area and its relationships with tectonic- and eustatic-induced variations of base-levels of erosion. Drainage network morphometry and the estimation of several topographic attributes have been added to the data collected through photo-aerial geomorphological interpretation and field survey. Drainage pattern, morphometric indexes and geological data seem to indicate that the thrust front is not active in the Late Quaternary. Paleotopographic reconstruction of ancient base-levels of erosion has permitted to calculated missing volumes. The estimation of eroded volumes in river valleys was performed through a GIS-aided calculation supported by a DEM with spatial resolution of 8 m, using the several orders of terraced deposits recognized in the area. The mapped remnants of relict geomorphological land surfaces have been interpolated by geospatial analysis and subtracted pixel by pixel to the present-day topography. Then, denudation rates were calculated on the basis of the relative age assigned to the deposits. Middle to upper Pleistocene denudation rates estimated by means of such an approach are about 0.1 mm/y, in good agreement with data coming from direct and indirect evaluation of transport sediment yield. The analysis of longitudinal river profiles using the stream power erosion model provided additional information on the incision rates of the studied area. The Late Quaternary uplift rate (0.15 mm/y), calculated on the basis of the elevation above sea level of the marine deposits outcropping in the easternmost sector of the study area, is quite similar to the erosion rates average value, so suggesting a steady-state fluvial incision.

  20. Sandstone-body and shale-body dimensions in a braided fluvial system: Salt wash sandstone member (Morrison formation), Garfield County, Utah

    USGS Publications Warehouse

    Robinson, J.W.; McCabea, P.J.

    1997-01-01

    Excellent three-dimensional exposures of the Upper Jurassic Salt Wash Sandstone Member of the Morrison Formation in the Henry Mountains area of southern Utah allow measurement of the thickness and width of fluvial sandstone and shale bodies from extensive photomosaics. The Salt Wash Sandstone Member is composed of fluvial channel fill, abandoned channel fill, and overbank/flood-plain strata that were deposited on a broad alluvial plain of low-sinuosity, sandy, braided streams flowing northeast. A hierarchy of sandstone and shale bodies in the Salt Wash Sandstone Member includes, in ascending order, trough cross-bedding, fining-upward units/mudstone intraclast conglomerates, singlestory sandstone bodies/basal conglomerate, abandoned channel fill, multistory sandstone bodies, and overbank/flood-plain heterolithic strata. Trough cross-beds have an average width:thickness ratio (W:T) of 8.5:1 in the lower interval of the Salt Wash Sandstone Member and 10.4:1 in the upper interval. Fining-upward units are 0.5-3.0 m thick and 3-11 m wide. Single-story sandstone bodies in the upper interval are wider and thicker than their counterparts in the lower interval, based on average W:T, linear regression analysis, and cumulative relative frequency graphs. Multistory sandstone bodies are composed of two to eight stories, range up to 30 m thick and over 1500 m wide (W:T > 50:1), and are also larger in the upper interval. Heterolithic units between sandstone bodies include abandoned channel fill (W:T = 33:1) and overbank/flood-plain deposits (W:T = 70:1). Understanding W:T ratios from the component parts of an ancient, sandy, braided stream deposit can be applied in several ways to similar strata in other basins; for example, to (1) determine the width of a unit when only the thickness is known, (2) create correlation guidelines and maximum correlation lengths, (3) aid in interpreting the controls on fluvial architecture, and (4) place additional constraints on input variables to stratigraphie and fluid-flow modeling. The usefulness of these types of data demonstrates the need to develop more data sets from other depositional environments.

  1. Rates of soil-litter mixing beneath and between shrub canopies in a semiarid shrubland: Combined effects of aeolian/fluvial redistribution

    NASA Astrophysics Data System (ADS)

    Power, R.; Melhem, T. H.; Field, J. P.; Breshears, D. D.; Archer, S. R.

    2010-12-01

    The redistribution of soil, litter, and other ecological resources by aeolian and fluvial processes has important biogeochemical implications for the functioning of semiarid ecosystems. Interactions between aeolian and fluvial processes at the vegetation-patch scale can give rise to increased resource heterogeneity at the landscape scale due to the redistribution of soil and litter from intercanopy areas to canopy areas beneath shrubs. Because of the sparse vegetation cover characteristic of most semiarid shrublands, these systems are generally highly susceptible to soil-litter mixing and resource redistribution by aeolian and fluvial transport processes. New developments suggest that rates of soil-litter mixing may greatly influence rates of litter decomposition in semiarid ecosystems, yet few studies have evaluated the degree to which sediment and litter are being mixed and redistributed on the soil surface. This study was initiated to better understand the temporal dynamics of soil-litter mixing in semiarid shrublands and to ultimately relate rates of soil-litter mixing beneath and between shrub canopies to rates of litter decomposition. Three individual shrubs and three shrub clusters were randomly selected in a semiarid shrubland at the Santa Rita Experimental Range located in southern Arizona. Repeat photography (Nikon Coolpix 5400) was used to characterize the ground cover in 0.5 m2 photo plots, which were located in each of the cardinal directions both beneath the shrub canopies and in the intercanopy areas surrounding the shrubs. Photographs were taken in the summer of 2009 and 2010 and were used to estimate rates of soil-litter movement for weekly and yearly time intervals. Preliminarily results suggest that the largest percent change in ground cover and rates of soil-litter mixing occurred in the intercanopy areas between the individual shrubs and shrub clusters. Rates of soil-litter mixing were relatively large for weekly time intervals with respect to the collective changes that were observed throughout the one-year study period. Further, rates of soil-litter mixing appear to be greater beneath and between shrub clusters than individual shrubs, suggesting that shrub clusters may have more important biogeochemical implications than individual shrubs with respect to resource redistribution at the plant-interspace scale.

  2. Coastal circulation and sediment dynamics in Hanalei Bay, Kaua'i, Hawaii: Part II: tracking recent fluvial sedimentation; isotope stratigraphy obtained in Summer 2005

    USGS Publications Warehouse

    Draut, Amy E.; Field, Michael E.; Bothner, Michael H.; Logan, Joshua B.; Casso, Michael A.; Baldwin, Sandra M.; Storlazzi, Curt D.

    2006-01-01

    Delivery and dispersal of fluvial sediment in Hanalei Bay, Kaua’i, Hawaii, have important implications for the health of local coral reefs. The reef community in Hanalei Bay represents a relatively healthy ecosystem. However, the reefs are periodically stressed by storm waves, and increases in sediment and dissolved substances from the Hanalei River have the potential to cause additional stress. Increased turbidity and sedimentation on corals during Hanalei River floods that occur in seasons of low wave energy, when sediment would not be readily remobilized and advected out of the bay, could affect the health and sustainability of coral reefs and the many associated species. Measurements of short-lived isotopes 7Be and 137Cs in sediment cores have been used to trace the thickness and distribution of terrestrial sediment in Hanalei Bay, in order to assess spatial and temporal patterns of sediment deposition and remobilization relative to coral-reef locations. A third isotope, 210Pb, derived primarily from seawater, provides additional information about recent sedimentary history. Isotope profiles and observations of sedimentary facies from cores collected at multiple locations in June 2005, and again in August 2005, indicate the presence of recent fluvial sediment and organic debris in the east part of the bay near the mouth of the Hanalei River. Away from the immediate vicinity of the river mouth, sediment in the uppermost 1 m below the sea floor had not retained a significant quantity of fluvial sediment within the eight months prior to either sampling effort. During the study interval in summer 2005 the Hanalei River had no major floods and there was relatively little sediment input to the bay. Sediment away from the river mouth was dominated by carbonate sand, although some terrestrial sediment was present in sub-sea-floor horizons. Sedimentary facies and isotope inventories throughout the bay showed substantial spatial heterogeneity. Sediment cores will be collected again at the same sites discussed here during early and late summer 2006. If possible, additional sites will be sampled in the Black Hole depocenter near the river mouth. Major floods in winter and spring 2006 are expected to leave a significant new sediment signal in the bay that should be detected in summer 2006.

  3. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio Fluvial-Deltaic Reservoirs of South Texas. [Quarterly] technical progress report, April 1, 1995June 30, 1995

    Microsoft Academic Search

    N. Tyler; R. A. Levey

    1995-01-01

    Advanced reservoir characterization techniques are being applied to selected reservoirs in the Frio Fluvial-Deltaic Sandstone (Vicksburg Fault Zone) trend of South Texas in order to maximize the economic producibility of resources in this mature oil play. More than half of the reservoirs in this depositionally complex play have already been abandoned, and large volumes of oil may remain unproduced unless

  4. Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio fluvial-deltaic reservoirs of South Texas. Technical progress report, January 1--March 31, 1996

    SciTech Connect

    Tyler, N.; Levey, R.A.

    1996-04-24

    Advanced reservoir characterization techniques are being applied to selected reservoirs in the Frio Fluvial-Deltaic Sandstone (Vicksburg Fault Zone) trend of South Texas in order to maximize the economic producibility of resources in this mature oil play. This project is developing interwell-scale geological facies models and assessing engineering attributes of Frio fluvial-deltaic reservoirs in selected fields in order to characterize reservoir architecture, flow-unit boundaries, and the controls that these factors exert on the location and volume of unrecovered mobile and residual oil. The goals of the Industrial Associates program that is the source of industry cofunding to this project are to (1) develop an understanding of sandstone architecture and permeability structure in a spectrum of fluvial-deltaic reservoirs deposited in high- to low-accommodation settings and (2) translate this understanding into more realistic, geologically constrained reservoir models to maximize recovery of hydrocarbons. Project work during the first quarter of 1996 consisted of Phase 3 tasks related to the transfer of technologies to industry. The two primary vehicles for transferring technologies evaluated in the Frio Fluvial-Deltaic Sandstone play (Vicksburg Fault Zone) are a series of two short courses and a microcomputer-based geologic advisor software program. In Rincon field, a three-dimensional (3-D) reservoir model is being constructed to more accurately calculate remaining volumes, and work during the first quarter focused on a sensitivity analysis of varying model parameters.

  5. Introduccion a la hidraulica de aguas subterraneas : un texto programado para auto-ensenanza

    USGS Publications Warehouse

    Bennett, Gordon D.

    1987-01-01

    Este ' texto programado esta diseflado para ayudarle a comprender la teoria de la hidniulica de aguas subterraneas por medio de la auto-enseflanza. La instrucci6n programada es un enfoque a una materia, un metodo de aprender;que no elimina el esfuerzo mental del proceso de aprendizaje. Algunas secciones de este programa necesitan solamente ser leidas; otras tendrian que ser elaboradas con lapiz y papel. Algunas preguntas pueden ser contestadas directamente; otras requieren calculos. A medida que se avanza en el texto, tendra que consultar frecuentemente textos o referencias sobre matematicas, mecanica de fluidos e hidrologia. En cada una de las ocho partes del texto, inicie el programa de instrucci6n leyendo la Secci6n 1. Elija una respuesta a la pregunta al final de la secci6n y dirijase a la nueva secci6n indicada al lado de la respuesta escogida. Si su respuesta fue correcta, pase a la secci6n que contiene materia nueva y otra pregunta, y proceda tal como en la Secci6n 1. Si su respuesta no fue correcta, dirijase a la secci6n que contiene explicaciones adicionales sobre el tema anterior y que le indica volver a la pregunta inicial e intentar de nuevo. En este caso, valdra Ia pena repasar el material de la secci6n anterior. Continue de esta man era en el programa hasta que llegue a Ia secci6n que indica el final de la parte. Observe que aunque las secciones estan en orden numerico en cada una de las ocho partes, por lo general, usted no procedeni en secuencia numerica (Secci6n 1 ala Secci6n 2, etc.) de principia a fin.

  6. Investigating microbial diversity and UV radiation impact at the high-altitude Lake Aguas Calientes, Chile

    NASA Astrophysics Data System (ADS)

    Escudero, Lorena; Chong, Guillermo; Demergasso, Cecilia; Farías, María Eugenia; Cabrol, Nathalie A.; Grin, Edmond; Minkley, Edwin, Jr.; Yu, Yeoungeob

    2007-09-01

    The High-Lakes Project is funded by the NAI and explores the highest perennial volcanic lakes on Earth in the Bolivian and Chilean Andes, including several lakes ~6,000 m elevation. These lakes represent an opportunity to study the evolution of microbial organisms in relatively shallow waters not providing substantial protection against UV radiation. Aguas Calientes (5,870 m) was investigated (November 2006) and samples of water and sediment collected at 1, 3, 5, and 10 cm depth. An Eldonet UV dosimeter positioned on the shore records UV radiation and temperature, and is logging data year round. A UV SolarLight sensor allowed acquisition of point measurements in all channels at the time of the sampling. UVA, UVB, and PAR peaks between 11:00 am and 1:00 pm reached 7.7 mW/cm2, 48.5 ?W/cm2, and 511 W/m2, respectively. The chemical composition of the water sample was analyzed. DNA was extracted and DGGE analyses with bacterial and archaeal 16S fragments were performed to describe microbial diversity. Antibiotic resistances were established previously in similar environments in Argentine Andean wetlands. In order to determine these resistances in our samples, they were inoculated onto LB and R2A media and onto R2A medium containing either chloramphenicol, ampicillin or tetracycline. Bacterial was higher than archeal cell number determined by RT-PCR in all the samples, reaching maximum total values of 5x10 5 cell mL-1. DGGE results from these samples and Licancabur summit lake (5,916 m) samples were also compared. Eight antibiotic-resistant Gram negative strains have been isolated with distinct resistance patterns.

  7. Fractal Dimension of the Hydrographic Pattern of Three Large Rivers in the Mediterranean Morphoclimatic System: Geomorphologic Interpretation of Russian (USA), Ebro (Spain) and Volturno (Italy) Fluvial Geometry

    NASA Astrophysics Data System (ADS)

    Donadio, Carlo; Magdaleno, Fernando; Mazzarella, Adriano; Mathias Kondolf, G.

    2015-07-01

    By applying fractal geometry analysis to the drainage network of three large watercourses in America and Europe, we have calculated for the first time their fractal dimension. The aim is to interpret the geomorphologic characteristics to better understand the morphoevolutionary processes of these fluvial morphotypes; to identify and discriminate geomorphic phenomena responsible for any difference or convergence of a fractal dimension; to classify hydrographic patterns, and finally to compare the fractal degree with some geomorphic-quantitative indexes. The analyzed catchment of Russian (California, USA), Ebro (Spain), and Volturno (Italy) rivers are situated in Mediterranean-climate regions sensu Köppen, but with different geologic context and tectonic styles. Results show fractal dimensions ranging from 1.08 to 1.50. According to the geological setting and geomorphic indexes of these basins, the lower fractal degree indicates a prevailing tectonics, active or not, while the higher degree indicates the stronger erosion processes on inherited landscapes.

  8. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic resevoir. Quarterly report, October 1, 1996--December 31, 1996

    SciTech Connect

    Allison, M.L.

    1997-03-01

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project.

  9. The influence of volcanism on fluvial depositional systems in a Cenozoic strike-slip basin, Denali fault system, Yukon Territory, Canada

    SciTech Connect

    Cole, R.B.; Ridgway, K.D. (Univ. of Rochester, NY (United States))

    1993-01-01

    The depositional history of the Eocene-Oligocene Burwash strike-slip basin is characterized by a transition from non-volcanic clastic sedimentation of the Amphitheater Formation to deposition of lavas and volcaniclastic rocks of the overlying lower Wrangell volcanic sequence. The purpose of this paper is twofold: (1) to document the contemporaneous fluvial and volcanic depositional history of a nonmarine strike-slip basin, and (2) to discuss the transition from non-volcanic to volcanic deposition in the context of strike-slip basin evolution. The authors indicate that the onset of volcanism within strike-slip basins can result in major reorganizations of drainage systems as well as changes in sediment sources.

  10. Ancient Martian Lakestands and Fluvial Processes in Iani Chaos: Geology of Light-Toned Layered Deposits and their Relationship to Ares Vallis Outflow Channels

    NASA Astrophysics Data System (ADS)

    Guallini, Luca; Gilmore, Martha; Marinangeli, Lucia; Thomas, Nicolas

    2015-04-01

    Iani Chaos is a ~30,000 square kilometers region that lies at the head of the Ares Vallis outflow channel system. Mapping of Ares Vallis reveals multiple episodes of erosion, probably linked to several discharge events from the Iani Chaos aquifer. We present the first detailed geomorphological map of the Iani region. Five chaos units have been distinguished with varying degrees of modification (primarily by erosion and fracturing), starting from a common terrain (Noachian highlands). We observe a general progressive decrease of their mean elevation from the Mesas, Mesas & Knobs and Hummocky (Hy) terrains to the Knobs and Knobby morphologies. This trend is consistent with an initial collapse of the original surface with an increase of the fracturing and/or of the erosion. Light-toned Layered Deposits (LLD) have been also mapped and described in Iani Chaos. These terrains are clearly distinguished by a marked light-toned albedo, high thermal inertia and a pervasively fractured morphology. LLD both fill the basins made by the collapsed chaotic terrains and are found to be partially modified by the chaos formation. LLD also overlap chaos mounds or are themselves eroded into mounds after deposition. These stratigraphic relationships demonstrate that LLD deposition occurred episodically in the Iani region and throughout the history of the development of the chaos. Water seems to have had an active role in the geological history of Iani. The composition and morphologies of the LLD are consistent with deposition in an evaporitic environment and with erosion by outflows, requiring stable water on the surface. For the first time, we have also mapped and analyzed potential fluvial features (i.e., channels, streamlined islands, terraces, grooved surfaces) on the surface of the LLD. These landforms describe a fluvial system that can be traced from central Iani and linked northward to Ares Vallis. Using topographic data, we have compared the elevation of the LLD and channel units and find that their altitudes are remarkably similar to the altitude of the floors of the major Ares Vallis channels. This is decisive evidence of 1) a possible fluvial system within Iani linked to the Ares Vallis outflow system, characterized by five episodes of outflow at least (S1 to S5), and 2) of the existence of the LLD within Iani during the occurrence of the outflows (i.e., the LLD are coeval with or postdate the Ares Vallis outflow channels). On the basis of our analysis, we propose the following formation model for Iani Chaos: 1) Initial fracturing and tectonic subsidence of the pristine Noachian materials and subsequent outflow erosion of the bedrock (Ares Vallis S1 channel origin); 2) Evaporitic deposition of older LLD units on top and between chaotic terrains. Layering suggests cyclic wetting and drying; 3) Tectonic subsidence and fluvial erosion of chaos and LLD (Ares Vallis S2 to S3 channels); 4) Deposition of younger LLD units in central and northern Iani; 5) Tectonic subsidence and outflows, erosion of chaos and LLD (Ares Vallis S4 to S5 channel origin and subsequent downdropping of NW and N(e) Iani).

  11. Stratigraphic analysis of eolian interactions with marine and fluvial deposits, Middle Jurassic Page Sandstone and Carmel Formation, Colorado Plateau, U.S.A.

    SciTech Connect

    Blakey, R.C.; Jones, L.S. [Northern Arizona Univ., Flagstaff, AZ (United States). Dept. of Geology; Havholm, K.G. [Univ. of Wisconsin, EauClaire, WI (United States). Dept. of Geology

    1996-03-01

    The eolian Page Sandstone (Middle Jurassic) in south-central Utah and adjacent Arizona consists of multiple mostly eolian sequences and sequence-bounding unconformities (super surfaces). The super surfaces are a powerful correlation tool that provide the basis for a detailed regional stratigraphic analysis of the Page Sandstone and coeval parts of the marine and coastal-plain Carmel Formation. Some Page Sandstone upper surfaces correlate with sharp lithologic breaks in the Carmel Formation that are interpreted as marine flooding surfaces. Others correlate with fluvial surfaces in the Carmel Formation. This study demonstrates that a sequence stratigraphic framework can be applied to sparsely fossiliferous eolian, sabkha, and restricted marine deposits in a marine-coastal setting. Using detailed sedimentologic and stratigraphic studies, tectonic, eustatic, and possibly climatic signals can be differentiated within the complex, cyclic facies patterns displayed in the Page Sandstone and Carmel Formation.

  12. Geological and petrophysical characterization of the Ferron sandstone for 3-D simulation of a fluvial-deltaic reservoir. [Quarterly progress report], October 1--December 31, 1995

    SciTech Connect

    Allison, M.L.

    1995-12-31

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Technical progress this quarter is divided into regional stratigraphy, case studies, and technology transfer activities. The Kf-2 contains more and cleaner sand, indicating a more wave-modified environment of deposition. The regional stratigraphy of the Ferron Sandstone outcrop belt from Last Chance Creek to Ferron Creek was described and interpreted. Photomosaics and a database of existing surface and subsurface data are being used to determine the extent and depositional environment of each parasequence, and the nature of the contacts with adjacent rocks or flow units. Detailed geological and petrophysical characterization of the primary reservoir lithofacies typically found in a fluvial-dominated deltaic reservoir, is continuing at selected case-study areas. Interpretations of lithofacies, bounding surfaces, and other geologic information are being combined with permeability measurements from closely spaced traverses and from drill-hole cores (described this quarter).

  13. Revitalizing a mature oil play: Strategies for finding and producing oil in Frio Fluvial-Deltaic Sandstone reservoirs of South Texas

    SciTech Connect

    Knox, P.R.; Holtz, M.H.; McRae, L.E. [and others

    1996-09-01

    Domestic fluvial-dominated deltaic (FDD) reservoirs contain more than 30 Billion barrels (Bbbl) of remaining oil, more than any other type of reservoir, approximately one-third of which is in danger of permanent loss through premature field abandonments. The U.S. Department of Energy has placed its highest priority on increasing near-term recovery from FDD reservoirs in order to prevent abandonment of this important strategic resource. To aid in this effort, the Bureau of Economic Geology, The University of Texas at Austin, began a 46-month project in October, 1992, to develop and demonstrate advanced methods of reservoir characterization that would more accurately locate remaining volumes of mobile oil that could then be recovered by recompleting existing wells or drilling geologically targeted infill. wells. Reservoirs in two fields within the Frio Fluvial-Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas, a mature play which still contains 1.6 Bbbl of mobile oil after producing 1 Bbbl over four decades, were selected as laboratories for developing and testing reservoir characterization techniques. Advanced methods in geology, geophysics, petrophysics, and engineering were integrated to (1) identify probable reservoir architecture and heterogeneity, (2) determine past fluid-flow history, (3) integrate fluid-flow history with reservoir architecture to identify untapped, incompletely drained, and new pool compartments, and (4) identify specific opportunities for near-term reserve growth. To facilitate the success of operators in applying these methods in the Frio play, geologic and reservoir engineering characteristics of all major reservoirs in the play were documented and statistically analyzed. A quantitative quick-look methodology was developed to prioritize reservoirs in terms of reserve-growth potential.

  14. Using sediment fingerprinting to understand the controls on the fluvial export of sediment associated lead and particulate carbon from eroding peatlands

    NASA Astrophysics Data System (ADS)

    Shuttleworth, Emma; Evans, Martin; Rothwell, James

    2015-04-01

    Peatlands are an important store of carbon as well as a sink of industrial legacy pollutants such as lead (Pb). However, large areas of peatlands are damaged and degraded which have implications for the long-term storage of carbon and Pb in these settings. One concern surrounds the transfer of Pb contaminated sediment to the fluvial system, and previous work has found evidence that substantial concentrations of Pb may be released as an initial 'lead-flush' during the early stages of storm events. However, the underlying controls on sediment production and how these may influence the timing of contaminated sediment export during hydrological events are unclear. This study utilises a sediment source fingerprinting approach to assess the controls of sediment production and mobilisation during storm events in the Peak District National Park, southern Pennines (UK). The blanket peats of the Peak District embody many problems and pressures faced by peatlands globally, and are amongst the most heavily eroded and contaminated in the world. Suspended sediment was collected using time integrated mass samplers (TIMS), deployed for the first time in a vertical stack, to allow the relative changes in the sediment sources during changing discharge conditions in a small headwater stream to be assessed. This study has found evidence of suspended sediment enriched in peat-derived material early in storms, thus confirming accepted models of organic sediment exhaustion during the course of storm events, and that organic sediment transport becomes limited between storms which occur in quick succession. The timing of this organic sediment exhaustion is linked to catchment wetness and rainfall intensity. The contaminated surface layer of the peat is releasing Pb into the fluvial system throughout the year, but a flushing of Pb early in storm events is only evident under certain meteorological and hydrological conditions. The findings of this study pose questions over future sediment release under predicted changes in climate.

  15. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. [Quarterly] report, January 1--March 31, 1994

    SciTech Connect

    Allison, M.L.

    1994-04-22

    The objective of this project is to develop a comprehensive, interdisciplinary, quantitative characterization of a fluvial-deltaic reservoir which will allow realistic interwell and reservoir-scale modeling to be used for improved oil-field development in similar reservoirs world wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a 3-D representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for interwell to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduce economic risks, increase recovery from existing oil fields, and provide more reliable reserve calculations. Transfer of the project results to the petroleum industry will be an integral component of the project. The technical progress is divided into several sections corresponding to subtasks outlined in the Regional Stratigraphy Task and the Case Studies Task of the original proposal. The primary objective of the Regional Stratigraphy Task is to provide a more detailed interpretation of the stratigraphy of the Ferron Sandstone outcrop belt from Last Chance Creek to Ferron Creek. The morphological framework established from the case studies will be used to generate subsequent flow models for the reservoir types. The primary objective of the Case Study Task is to develop a detailed geological and petrophysical characterization, at well-sweep scale or smaller, of the primary reservoir lithofacies typically found in a fluvial-dominated deltaic reservoir. Sedimentary structures, lithofacies, bounding surfaces, and permeabilities measured along closely spaced traverses (both vertical and horizontal) will be combined with data from core drilling to develop a 3-D morphology of the reservoirs within each case study area.

  16. Model of fluvial deposition for control of oil migration and entrapment in upper Eocene to Oligocene Sespe Formation, West Montalvo field, Ventura County, California

    SciTech Connect

    Sadler, R.K.

    1988-03-01

    The Sespe Formation consists of continental red beds deposited during the tectonism that resulted as the Pacific-Farallon spreading ridge approached the North American plate. The Sespe at West Montalvo field is over 7000 ft thick and consists predominantly of fine to medium-grained sandstones interbedded with siltstone and mudstone deposited in the central part of the Oligocene basin. Oil production was established in 1951 from the upper 2000 ft, known as the Colonia zone. The Colonia zone has been subdivided into six sandstone packages 350-600 ft thick, based on a model of laterally migrating fluvial systems that created local intraformational unconformities. These systems had unique depositional characteristics that can be inferred from well-log analysis and related to facies described in outcrops surrounding the Ventura basin. These characteristics include sandstone to shale ratios, relative bed thicknesses, lateral continuity of sandstone and shale interbeds, and whether the sandstone beds exhibit normal or reverse grading, or have sharp bases and tops. The fluvial environments include small braided distributary streams, larger trunk streams, and broad shallow braided streams. All of the sandstone packages contain oil-bearing beds, but the package in which the sediments were apparently deposited in a system of broad, shallow braided streams is the most oil-prone. These sandstones are relatively thin, have sharp bases and tops, and are laterally continuous across parts of the field. The rapid sedimentation and the cut-and-fill processes of braided streams may have created interconnecting fluid pathways that allowed the migration and updip accumulation of oil.

  17. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly progress report, July 1--September 30, 1995

    SciTech Connect

    Allison, M.L.

    1995-10-30

    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project. Technical progress this quarter is divided into regional stratigraphy, case studies, stochastic modeling and fluid-flow simulation, and technology transfer activities. The regional stratigraphy of the Ferron Sandstone outcrop belt is being described and interpreted. Detailed geological and petrophysical characterization of the primary reservoir lithofacies typically found in a fluvial-dominated deltaic reservoir, is continuing at selected case-study areas. Interpretations of lithofacies, bounding surfaces, and other geologic information are being combined with permeability measurements from closely spaced traverses and from drill-hole cores (existing and two drilled during the quarter). Petrophysical and statistical analyses are being incorporated with the geological characterization to develop a three-dimensional model of the reservoirs through fluid-flow simulation.

  18. Aggradation of gravels in tidally influenced fluvial systems: Upper Albian (Lower Cretaceous) on the cratonic margin of the North American Western Interior foreland basin

    USGS Publications Warehouse

    Brenner, Richard L.; Ludvigson, Greg A.; Witzke, B.L.; Phillips, P.L.; White, T.S.; Ufnar, David F.; Gonzalez, Luis A.; Joeckel, R.M.; Goettemoeller, A.; Shirk, B.R.

    2003-01-01

    Alluvial conglomerates were widely distributed around the margin of the Early Cretaceous North American Cretaceous Western Interior Seaway (KWIS). Conglomerates, sandstones, and lesser amounts of mudstones of the upper Albian Nishnabotna Member of the Dakota Formation were deposited as fill-in valleys that were incised up to 80 m into upper Paleozoic strata. These paleovalleys extended southwestward across present-day northwestern Iowa into eastern Nebraska. Conglomerate samples from four localities in western Iowa and eastern Nebraska consist mostly of polycrystalline quartz with lesser amounts of microcrystalline (mostly chert), and monocrystalline quartz. Previous studies discovered that some chert pebbles contain Ordovician-Pennsylvanian invertebrate fossils. The chert clasts analyzed in this study were consistent with these findings. In addition, we found that non-chert clasts consist of metaquartzite, strained monocrystalline quartz and 'vein' quartz from probable Proterozic sources, indicating that parts of the fluvial system's sediment load must have travelled distances of 400-1200 km. The relative tectonic stability of this subcontinent dictated that stream gradients were relatively low with estimates ranging from 0.3 to 0.6 m/km. Considering the complex sedimentologic relationships that must have been involved, the ability of low-gradient easterly-sourced rivers to entrain gravel clasts was primarily a function of paleodischarge rather than a function of steep gradients. Oxygen isotopic evidence from Albian sphaerosiderite-bearing paleosols in the Dakota Formation and correlative units from Kansas to Alaska suggest that mid-latitude continental rainfall in the Albian was perhaps twice that of the modern climate system. Hydrologic fluxes may have been related to wet-dry climatic cycles on decade or longer scales that could account for the required water supply flux. Regardless of temporal scale, gravels were transported during 'high-energy' pulses, under humid climatic conditions in large catchment areas. An overall rising sea level during the late Albian created accommodation space for the gravelly lithofacies equivalent to the Kiowa-Skull Creek rocks. As Western Interior sea level rose, regional stream gradients were reduced, resulting in regional fluvial aggradation. The conglomeratic lower parts of the Nishnabotna Member of the Dakota Formation formed the transgressive systems tract within an upper Albian sequence that is defined by two unconformities that can be traced from marine Kiowa strata in western Kansas northeastward into western Iowa (Brenner et al., 2000). Mud-draped cross-bedded sandstone bodies, laminated mudstone intervals, and vertical burrows in the lower strata of the Nishnabotna Member indicate that estuarine conditions existed at the mouths of the river system, and tidal effects were transmitted at least 200 km inland from the interpreted late Albian coast. These observations suggest that estuarine conditions stepped up the incised valleys as fluvial sediments aggraded in response to regional transgression that continued through the Late Albian. ?? 2003 Elsevier Ltd. All rights reserved.

  19. pp iii The importance of high-resolution monitoring in erosion and deposition dynamics studies: examples from estuarine and fluvial systems

    NASA Astrophysics Data System (ADS)

    Lawler, D. M.

    2005-01-01

    Erosion and deposition processes lie at the centre of geomorphological explanation, but progress in understanding has been limited by a lack of appropriate high-resolution monitoring methodologies which permit detection of erosion and deposition dynamics. This paper presents a case for monitoring erosion and deposition at high temporal resolutions, and uses hypothetical approaches supported by example erosion and deposition events and analyses drawn from estuarine and fluvial systems. The paper first presents testable hypotheses to demonstrate the complexity of possible event combinations, sequences and juxtapositions for the erosion driving forces which underpin the need for high-resolution monitoring. Second, it summarises recent improvements to the Photo-Electronic Erosion Pin (PEEP) automatic erosion and deposition monitoring system, including the novel concept of Thermal Consonance Timing (TCT), which is particularly promising because it helps to define the timing of nocturnal events and through the entire hydrograph. Third, example results are discussed from high-resolution monitoring of bank erosion at a tidal site at Burringham on the River Trent in northern England. Tidal banks are revealed to be much more dynamic than previous conventional monitoring has indicated. A key result is that, because the high-resolution approach allows erosional and depositional activity to be assigned to specific periods of tidal inundation, it becomes possible for the first time routinely to produce 'event-based' erosion (36 mm h -1) and deposition rates (4.5 and 8.4 mm h -1). Such rate determinations are potentially very useful in the field validation of sedimentological and geomorphological models, including grain settling and resuspension theory. Fourth, through a longer term of aggregated daily data, a striking 2-week cycle of deposition and erosion emerges which correlates most strongly with spring-neap tidal cycling, but is moderated by wind stress effects. Sediment was deposited on the bank relatively quickly, over 4-5 days, but then removed by erosion rather slowly, over 9-10 days. Fifth, the dangers of low-resolution monitoring are illustrated by comparing the daily PEEP data set with a series resampled at a lower (14-day) frequency, to simulate the information generated by conventional resurvey methodologies. The low-frequency series failed adequately to represent the cyclicity, mean, range, variability and trend of bank elevation changes, and without this dynamics information, rate and process definition is very difficult, largely because of self-concealing activity. Sixth, a useful advance is illustrated by the fluvial erosion sequence for the River Wharfe (N. England). This shows how TCT can generate rare and important results with the definition of the precise time of an erosion event within the hydrograph: bank retreat here occurred very quickly, after initial inundation, and within 4 h of the flow peak-information which can be used to define thresholds for entrainment (e.g. critical shear stresses). Such high-resolution monitoring helps to unravel some of the erosional effects of complex sequences, combinations and juxtapositions of similar or different forcing events. Finally, high-resolution approaches have been adopted worldwide for fluvial, estuarine, mudflat and canal systems, but considerable potential exists for their development and use in these and other contexts (e.g. gully, hillslope, beach and dune environments), to improve understanding and modelling of geomorphological processes more widely.

  20. Architecture of pre-vegetation sandy-braided perennial and ephemeral river deposits in the Paleoproterozoic Athabasca Group, northern Saskatchewan, Canada as indicators of Precambrian fluvial style

    NASA Astrophysics Data System (ADS)

    Long, Darrel G. F.

    2006-08-01

    The Late Paleoproterozoic Athabasca Basin contains more than 1.5 km of predominantly sandy strata, most of which are of braided fluvial origin. In the eastern part of the basin, at McClean Lake, sandstones and minor conglomerates of the Read Formation at the base of the succession are preserved within a steep-walled valley system. They consist predominantly of meter-scale sheet elements, characterized by massive and flat-laminated fine- to very coarse-grained sandstone with minor discontinuous cobble and boulder conglomerate along lower set boundaries. These are interpreted as sheet-flood and stream-flood deposits of a terminal dry-land system, deposited in an arid climatic setting. Analysis of closely spaced drill-core indicates that late stage run-off was confined to small shallow channels, typically only a few tens of meters wide and a few meters deep. Overlying strata of the Bird Member of the Manitou Falls Formation are predominantly coarse- to very coarse-grained sandstones with abundant small-scale cross-stratification and minor granule and small pebble conglomerate. At McClean Lake, these appear to have been deposited as sheet-elements by semi-ephemeral to perennial braided rivers under more humid conditions. At Key Lake, 160 km to the southwest, architectural analysis of a 184 m wide section indicates that at least part of the Bird Member was deposited in deeper, sandy-braided rivers characterized by seasonally varied flow. The closest modern analogue is the South Saskatchewan River, in which large simple flow-transverse bedforms become exposed and dissected during falling stage, and act as nuclei for sand-flat development. The presence of numerous low-relief 4th order surfaces suggests continued reworking of bar-tops during rising stage. The incremental character of downstream accretionary elements suggests periodic migration of barforms during peak-flood stages, separated by periods of low flow. This indicates similarities with modern perennial braided systems, and is counter to the idea that all pre-Devonian fluvial systems should consist of stacked sheets formed by individual flood events. Thin gravel layers accumulated as lags on fourth order surfaces, with discontinuous mud layers suggesting deposition within temporary ponds in channel thalwegs after major floods. Strata in overlying units indicate a return to semi-perennial conditions.

  1. Evolution and preservation potential of fluvial and transgressive deposits on the Louisiana inner shelf: understanding depositional processes to support coastal management

    NASA Astrophysics Data System (ADS)

    Flocks, James; Miner, Michael D.; Twichell, David C.; Lavoie, Dawn L.; Kindinger, Jack

    2009-12-01

    The barrier-island systems of the Mississippi River Delta plain are currently undergoing some of the highest rates of shoreline retreat in North America (~20 m/year). Effective management of this coastal area requires an understanding of the processes involved in shoreline erosion and measures that can be enacted to reduce loss. The dominant stratigraphy of the delta plain is fluvial mud (silts and clays), delivered in suspension via a series of shallow-water delta lobes that prograded across the shelf throughout the Holocene. Abandonment of a delta lobe through avulsion leads to rapid land subsidence through compaction within the muddy framework. As the deltaic headland subsides below sea level, the marine environment transgresses the bays and wetlands, reworking the available sands into transgressive barrier shorelines. This natural process is further complicated by numerous factors: (1) global sea-level rise; (2) reduced sediment load within the Mississippi River; (3) diversion of the sediment load away from the barrier shorelines to the deep shelf; (4) storm-induced erosion; and (5) human alteration of the littoral process through the construction of hardened shorelines, canals, and other activities. This suite of factors has led to the deterioration of the barrier-island systems that protect interior wetlands and human infrastructure from normal wave activity and periodic storm impact. Interior wetland loss results in an increased tidal prism and inlet cross-sectional areas, and expanding ebb-tidal deltas, which removes sand from the littoral processes through diversion and sequestration. Shoreface erosion of the deltaic headlands does not provide sufficient sand to balance the loss, resulting in thinning and dislocation of the islands. Abatement measures include replenishing lost sediment with similar material, excavated from discrete sandy deposits within the muddy delta plain. These sand bodies were deposited by the same cyclical processes that formed the barrier islands, and understanding these processes is necessary to characterize their location, extent, and resource potential. In this paper we demonstrate the dominant fluvial and marine-transgressive depositional processes that occur on the inner shelf, and identify the preservation and resource potential of fluvio-deltaic deposits for coastal management in Louisiana.

  2. Facies analyses of cold-water spring-fed fluvial carbonates: Implications for a terrestrial Holocene (?) record of wet events in Southern California

    NASA Astrophysics Data System (ADS)

    Ibarra, Y.; Corsetti, F. A.; Feakins, S. J.

    2012-12-01

    Fluvial, cold-water carbonate spring deposits located near Zaca Lake (Santa Barbara County, California) are terrestrial evidence of wetter-than-present climatic conditions in this region's past. While cold-water fed fluvial carbonates (tufa) can record past pluvials, many sites are hampered by inherently complex sedimentology and diagenesis that complicates the generation of high-resolution climate records. Here, we focus on the carbonate facies at different scales (macro, meso, micro) in order to best interpret paleoenvironmental information. The carbonates are approximately 0.2-1m thick and extend for ~200m along a narrow valley bound between two steep ridges. Modern flow rates from a boxed spring located upstream from the carbonates range from 0.3-0.7 L/sec; rates are insufficiently high for any active carbonate deposition downstream. At least two episodes of carbonate growth have been detected. One is a perched deposit that extends for about 15m along the slope of a ridge and contains a ~10m steep vertical cascade facies. Extensive diagenetic alteration of the carbonate is present based on at least three generations of post depositional cement growth. The other deposit extends for about 200m and contains terrace, pool, and cascade facies. Petrographic analyses of the carbonate fabric revealed a significant microbiologic component including well-preserved primary calcite biosignatures of the cold (9-13°C), freshwater microalgae Oocardium stratum. Oxygen isotopic values of the Oocardium calcite range from -7.4 to -6.9 per mil VPDB. Using the isotopic composition of modern spring water as an approximation of the recent past, we calculate a depositional temperature of 14°C using the oxygen isotope paleotemperature equation; the results are in agreement with modern Oocardium-bearing deposits. Radiocarbon age dating of organic detritus as well as optically stimulated luminescence dating techniques are currently under investigation to determine when carbonate growth was active. The presence of groundwater-fed carbonate deposits in this region constitute a unique opportunity to compare/compliment a record of terrestrial wet events to proximal high-resolution records of Holocene climate from the sediments of Zaca Lake located about 2km away and the diverse assemblage of Holocene climate records from the Santa Barbara Basin located about 50km to the south.

  3. Far-field stress changes and progressive rock slope instability resulting from fluvial incision at the axis of a major Alpine valley

    NASA Astrophysics Data System (ADS)

    Leith, Kerry; Moore, Jeffrey R.; Loew, Simon; Krautblatter, Michael

    2014-05-01

    Geomorphic processes alter both the form and near-surface structure of alpine rock slopes. These processes drive progressive changes in the magnitude of shear, normal, and tensile stresses, and where in situ stresses exceed intact or rock mass failure envelopes, can lead to local rock mass destabilization. Such destabilization is most commonly attributed to 'debuttressing' causing a loss of support from adjacent bodies, or a reduction in effective rock mass strength as critical planes of weakness are 'undercut' by erosional processes. Where stress changes are lower in magnitude, progressive rock slope failure is often attributed to a shift in near-critical stresses toward the brittle failure envelope, allowing local stress concentrations to propagate existing fractures or weaken existing joints. We model the development of long-term in situ stresses within an alpine valley affected by ongoing tectonic and erosional processes. We allow for the mechanical effects of long-term bedrock strength limits, and analyze the magnitude of far-field stress changes associated with 100 m of fluvial incision at the axis of a 3000 m wide, 2500 m deep alpine valley. Our model configuration mirrors the erosional history of the Matter Valley (southern Swiss Alps) at the location of the 30 x 106 m3 Randa rock slope failure. We find that incision focuses stresses at the valley floor, reducing stress magnitudes throughout the remainder of the landscape. This effect is particularly strong near the valley shoulder, where decreases in shear stress are approximately half those of normal stresses. Although the magnitude of changes are relatively low (10's to 100's of kPa), we find incision may have had a negative impact on the stability of rock slopes over 1000 m from the valley axis, perhaps initiating progressive failure of the Randa rock slope. This proposition is supported by the presence of glacial striations within large tension cracks above the Randa rock slope failure. These formed during, or prior to the Last Glacial Maximum, indicating progressive rock slope failure was already well underway by this time, and along with an analysis of temporal fluvial incision, suggest destabilization most likely initiated during the interglacial at MIS 3. Such progressive failure is particularly important in alpine regions, as its initiation requires relatively minor morphological change, and the resulting strength degradation modulates temporal increases in rock slope sensitivity.

  4. Impact of change in erosion rate and landscape steepness on hillslope and fluvial sediments grain size in the Feather River Basin (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Attal, M.; Mudd, S. M.; Hurst, M. D.; Weinman, B.; Yoo, K.; Naylor, M.

    2014-10-01

    The characteristics of the sediment transported by rivers (e.g., sediment flux, grain size distribution - GSD -) dictate whether rivers aggrade or erode their substrate. They also condition the architecture and properties of sedimentary successions in basins. In this study, we investigate the relationship between landscape steepness and the grain size of hillslope and fluvial sediments. The study area is located within the Feather River Basin in Northern California, and studied basins are underlain exclusively by tonalite lithology. Erosion rates in the study area vary over an order of magnitude, from > 250 mm ka-1 in the Feather River canyon to < 15 mm ka-1 on an adjacent low relief plateau. We find that the coarseness of hillslope sediment increases with increasing hillslope steepness and erosion rates. We hypothesize that, in our soil samples, the measured ten-fold increase in D50 and doubling of the amount of fragments larger than 1 mm when slope increases from 0.38 to 0.83 m m-1 is due to a decrease in the residence time of rock fragments, causing particles to be exposed for shorter periods of time to processes that can reduce grain size. For slopes in excess of 0.7 m m-1, landslides and scree cones supply much coarser sediment to rivers, with D50 and D84 more than one order of magnitude larger than in soils. In the tributary basins of the Feather River, a prominent break in slope developed in response to the rapid incision of the Feather River. Downstream of the break in slope, fluvial sediment grain size increases, due to an increase in flow competence (mostly driven by channel steepening) but also by a change in sediment source and in sediment dynamics: on the plateau upstream of the break in slope, rivers transport easily mobilised fine-grained sediment derived exclusively from soils. Downstream of the break in slope, mass wasting processes supply a wide range of grain sizes that rivers entrain selectively, depending on the competence of their flow. Our results also suggest that in this study site, hillslopes respond rapidly to an increase in the rate of base-level lowering compared to rivers.

  5. Impact of change in erosion rate and landscape steepness on hillslope and fluvial sediments grain size in the Feather River basin (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Attal, M.; Mudd, S. M.; Hurst, M. D.; Weinman, B.; Yoo, K.; Naylor, M.

    2015-03-01

    The characteristics of the sediment transported by rivers (e.g. sediment flux, grain size distribution - GSD) dictate whether rivers aggrade or erode their substrate. They also condition the architecture and properties of sedimentary successions in basins. In this study, we investigate the relationship between landscape steepness and the grain size of hillslope and fluvial sediments. The study area is located within the Feather River basin in northern California, and studied basins are underlain exclusively by tonalite lithology. Erosion rates in the study area vary over an order of magnitude, from >250 mm ka-1 in the Feather River canyon to <15 mm ka-1 on an adjacent low-relief plateau. We find that the coarseness of hillslope sediment increases with increasing hillslope steepness and erosion rates. We hypothesise that, in our soil samples, the measured 10-fold increase in D50 and doubling of the amount of fragments larger than 1 mm when slope increases from 0.38 to 0.83 m m-1 is due to a decrease in the residence time of rock fragments, causing particles to be exposed for shorter periods of time to processes that can reduce grain size. For slopes in excess of 0.7 m m-1, landslides and scree cones supply much coarser sediment to rivers, with D50 and D84 more than one order of magnitude larger than in soils. In the tributary basins of the Feather River, a prominent break in slope developed in response to the rapid incision of the Feather River. Downstream of the break in slope, fluvial sediment grain size increases, due to an increase in flow competence (mostly driven by channel steepening) as well as a change in sediment source and in sediment dynamics: on the plateau upstream of the break in slope, rivers transport easily mobilised fine-grained sediment derived exclusively from soils. Downstream of the break in slope, mass wasting processes supply a wide range of grain sizes that rivers entrain selectively, depending on the competence of their flow. Our results also suggest that, in this study site, hillslopes respond rapidly to an increase in the rate of base-level lowering compared to rivers.

  6. Quantifying bedload modifications during fluvial transport and their influence on detrital provenance analysis: a combined experimental, field and numerical study in the central Southern Alps of New Zealand

    NASA Astrophysics Data System (ADS)

    Flükiger, Lukas; Herman, Frédéric; Beyssac, Olivier; Cox, Simon; Lavé, Jerome

    2013-04-01

    Quantifying catchment scale erosion is key to understanding landscape evolution. To that end, detrital provenance studies, in which sediments are collected at the outlet of a catchment, have become increasingly popular in geomorphology. Here we perform a provenance analysis on detrital sands to infer spatial patterns of erosion at the catchment-scale using Raman spectroscopy on carbonaceous material, which provides an estimate of the peak temperature (RSCM-T) experienced during metamorphism of rocks. We focus on the Whataroa River in the Southern Alps of New Zealand and exploit the well-constrained metamorphic gradient that runs parallel to drainage direction. The relative ease of making measurements enables us to acquire a large amount of data within the eroding catchment. While the distribution of RSCM-T in detrital sands primarily reflects spatial distribution of erosion rates, it can also be influenced by various factors such as initial sand content of sediment supplied to the river network, sand production by pebbly bedload abrasion during fluvial transport and organic carbon content in exposed bedrock. In order to account for these effects when unraveling spatial distribution of erosion rates from the observed RSCM-T, we first measured abrasion properties through flume experiments and total organic carbon (TOC) content in the bedrock within the catchment, and then introduced these parameters into a mass-conservative model that includes pebble abrasion during transport along the fluvial network. The flume experiment reveals that internally 'weak' lithologies, such as micaschist, produce significantly more fine particles (silt to coarse sand) than more durable lithologies, such as sandstone. This result is important because it reveals the potential biases might be arisen when conducting provenance analyses on sand. Finally, contrary to the long-term patterns of uplift and exhumation, present day erosion rates are highest ten kilometres from the Alpine Fault, where the greatest amounts of contemporary uplift are measured by continuous GPS survey. This result has implications for our understanding of the coupling between tectonics, climate and erosion in the tectonically active areas such as the Southern Alps of New Zealand.

  7. Fluvial system response to abrupt climate change: sedimentary record example of the Paleocene-Eocene Thermal Maximum (PETM) in the South-Pyrenean foreland basin, Spain

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Castelltort, Sebastien; Foreman, Brady; Hassenruck-Gudipati, Hima J.

    2015-04-01

    The "Paleocene-Eocene Thermal Maximum" (PETM), is understood to be an extreme and short-lived (ca.150-220kya) global warming event that occurred 55.8 million years ago and during which global annual temperatures are estimated to have increased by ca. 5-8°C, with respect to sea surface temperatures and ca. 4-5°C, with respect to the deep sea. A remaining outstanding question is: in addition to the global increase in temperature, how was precipitation perturbed during the event, and how did fluvial surface processes respond to the perturbation? In the southern Spanish Pyrenees, the Paleocene succession of the Tremp-Graus Basin is made up of the Talarn (Danian) and Esplugafreda (Thanetian) red bed formations. The Esplugafreda section is composed of approximately 250m of reddish paleosols and contains numerous lenticular bodies of calcareous conglomerates, which are interpreted as braided channels. The Esplugafreda Formation is overlain by the Claret Conglomerate -- an extensive sheet-like unit which ranges in thickness between 1m and 4m of clast-supported calcareous conglomerate and pebbly calcarenites and is interpreted as marking the fluvial response to a dramatic climate change, in the form of the transformation of a braided river and floodplain system into an enormous conglomeratic braided plain (formed over at least 2000km2 conservatively) due to dramatic change in the hydrologic cycle. The conglomerate unit ends abruptly and is overlaid by fine-grained yellowish soils which are mainly made up of silty mudstones with abundant small size carbonate nodules suggesting another shift in the hydrological cycle after the PETM. Here we present paleo-channel geometry and grain size data collected in the southern Pyrenees (Tremp, Aren, and Serraduy sections) that we invert to reconstruct paleoflow conditions during the Paleocene and during the Paleocene-Eocene Thermal Event. We confront paleohydraulic results with sea level, isotope and lithological records in order to understand river response to the PETM climate change and try to assess the possible precipitation perturbations at the PETM in the study area and how these are transferred into the sedimentary record.

  8. Relative contribution of Precambrian metamorphic rocks and Cretaceous-Tertiary igneous rocks to Oligocene and Holocene fluvial sands and the unroofing of a magmatic arc

    SciTech Connect

    Molinaroli, E.; Basu, A. (Indiana Univ., Bloomington (United States))

    1991-03-01

    Oligocene and Holocene fluvial sands were deposited in small extensional basins in a magmatic arc in southwestern Montana under relatively humid and semi-arid conditions, respectively. The source rocks are roof-pendants and thrust-slices of Precambrian metamorphic rocks (PCM) and Cretaceous-Tertiary igneous rocks (KTI) that make up the arc. The authors have surveyed 143,607 heavy mineral grains (HMGs) in polished thin sections of 55 samples collected from adjacent but discrete geomorphologic units. In the Holocene sands, of 5440 HMGs 519 are garnets and of 97,667 HMGs 395 are zircons. In the Oligocene sandstones, of 6397 HMGs 998 are garnets, and of 45,940 HMGs 331 are zircons. Garnets are absent in the igneous rocks and zircons are extremely rare in the metamorphic rocks. Garnets ar estimated to be about 100 times as abundant in the metamorphic rocks as the zircons are in the igneous rocks. Mass balance calculations show that the proportion of PCM/(PCM+KTI) ranges from 0 to 21% in Oligocene sandstones, and from 3 to 76% in Holocene sands in different local units. However, the overall PCM/(PCM+KTI) proportions in the Holocene and the Oligocene sands in southwestern Montana are 19% and 18%, respectively. This suggests that the roof pendants, thrust slices, and magmatic arc rocks have been unroofed in constant proportions since the Oligocene although locally the proportions have been different.

  9. Improved oil recovery in fluvial dominated deltaic reservoirs of Kansas - Near-term. Annual report, June 18, 1993--June 18, 1994

    SciTech Connect

    Green, D.W.; Willhite, G.P.

    1995-10-01

    Common oil field problems exist in fluvial dominated deltaic reservoirs in Kansas. The problems are poor waterflood sweep and lack of reservoir management. The poor waterflood sweep efficiency is due to (1) reservoir heterogeneity, (2) channeling of injected water through high permeability zones or fractures, and (3) clogging of water injection wells with solids as a result of poor water quality. In many instances the lack of reservoir management is due to lack of (1) data collection and organization, (2) integrated analysis of existing data by geological and engineering personnel, and (3) identification of optimum recovery techniques. Two demonstration sites operated by different independent oil operators are involved in the project. The Nelson Lease (an existing waterflood) is located in Allen County, Kansas in the N.E. Savonburg Field and is operated by James E. Russell Petroleum, Inc. The Stewart Field (on the latter stage of primary production) is located in Finney County, Kansas and is operated by Sharon Resources, Inc. The objective is to increase recovery efficiency and economics in these type of reservoirs. The technologies being applied to increase waterflood sweep efficiency are (1) in situ permeability modification treatments, (2) infill drilling, (3) pattern changes, and (4) air flotation to improve water quality. The technologies being applied to improve reservoir management are (1) database development, (2) reservoir simulation, (3) transient testing, (4) database management, and (5) integrated geological and engineering analysis.

  10. Gully annealing by aeolian sediment: field and remote-sensing investigation of aeolian-hillslope-fluvial interactions, Colorado River corridor, Arizona, USA

    NASA Astrophysics Data System (ADS)

    Sankey, Joel B.; Draut, Amy E.

    2014-09-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This study of gully annealing by aeolian sediment, spanning 95 km along the Colorado River corridor in Glen, Marble, and Grand Canyon, Arizona, USA, employed field and remote sensing observations, including digital topographic modelling. Results indicate that aeolian sediment activity can be locally effective at counteracting gully erosion. Gullies are less prevalent in areas where surficial sediment undergoes active aeolian transport, and have a greater tendency to terminate in active aeolian sand. Although not common, examples exist in the record of historical imagery of gullies that underwent infilling by aeolian sediment in past decades and evidently were effectively annealed. We thus provide new evidence for a potentially important interaction of aeolian-hillslope-fluvial processes, which could affect dryland regions substantially in ways not widely recognized. Moreover, because the biologic soil crust plays an important role in determining aeolian sand activity, and so in turn the extent of gully development, this study highlights a critical role of geomorphic-ecologic interactions in determining arid-landscape evolution.

  11. Identification and evaluation of fluvial-dominated deltaic (Class 1 oil) reservoirs in Oklahoma. Quarterly technical progress report, January 1, 1995--March 31, 1995

    SciTech Connect

    Mankin, C.J. [Oklahoma Geological Survey, Norman, OK (United States)] [Oklahoma Geological Survey, Norman, OK (United States); Banken, M.K. [Oklahoma Univ., Norman, OK (United States)] [Oklahoma Univ., Norman, OK (United States)

    1995-07-07

    The Oklahoma Geological Survey (OGS), the Geological Information Systems department, and the School of Petroleum and Geological Engineering at the University of Oklahoma are engaging in a program to identify and address Oklahoma`s oil recovery opportunities in fluvial-dominated deltaic (FDD) reservoirs. This program includes the systematic and comprehensive collection and evaluation of information on all of Oklahoma`s FDD reservoirs and the recovery technologies that have been (or could be) applied to those reservoirs with commercial success. This data collection and evaluation effort will be the foundation for an aggressive, multifaceted technology transfer program that is designed to support all of Oklahoma`s oil industry, with particular emphasis on smaller companies and independent operators in their attempts to maximize the economic producibility of FDD reservoirs. Specifically, this project will identify all FDD oil reservoirs in the State; group those reservoirs into plays that have similar depositional and subsequent geologic histories; collect, organize and analyze all available data; conduct characterization and simulation studies on selected reservoirs in each play; and implement a technology transfer program targeted to the operators of FDD reservoirs to sustain the life expectancy of existing wells with the ultimate objective of increasing oil recovery. The elements of the technology transfer program include developing and publishing play portfolios, holding workshops to release play analyses and identify opportunities in each of the plays, and establishing a computer laboratory that is available for industry users.

  12. Water table dynamics and groundwater-surface water interaction during filling and draining of a large fluvial island due to dam-induced river stage fluctuations

    NASA Astrophysics Data System (ADS)

    Francis, Blair A.; Francis, Luke K.; Cardenas, M. Bayani

    2010-07-01

    Dam-controlled river stage fluctuations alter groundwater-surface water interaction between persistent bars and islands and the rivers bounding them by rapidly changing hydraulic gradients and expanding hyporheic zones. A 300-m long and 80-m wide sand-gravel island with established vegetation located on the Colorado River (Austin, Texas, USA) is subjected to >1 m daily river stage variations due to upstream dam operations. Piezometer nests with probes monitored the evolution of the water table and groundwater flow paths through several cycles of dam-induced stage fluctuations. Results show that hydraulic head and the water table within the island closely track the river stage associated with dam release. Water table mounds and depressions which overlap in time were mapped through the course of one storage-release cycle over which >4,000 m3 of water moved in and out of the island. Dam operations have drastically altered groundwater-surface water connectivity between the Colorado River and the fluvial island aquifer by pumping substantial amounts of water in and out of the aquifer during dam release and storage cycles.

  13. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Annual report, September 29, 1993--September 29, 1994

    SciTech Connect

    Allison, M.

    1995-07-01

    The objective of the Ferron Sandstone project is to develop a comprehensive, interdisciplinary, quantitative characterization of a fluvial-deltaic reservoir to allow realistic inter-well and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Quantitative geological and petrophysical information on the Cretaceous Ferron Sandstone in east-central Utah will be collected. Both new and existing data will be integrated into a three-dimensional model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project. This report covers research activities for fiscal year 1993-94, the first year of the project. Most work consisted of developing field methods and collecting large quantities of existing and new data. We also developed preliminary regional and case-study area interpretations. The project is divided into four tasks: (1) regional stratigraphic analysis, (2) case studies, (3) development of reservoirs models, and (4) field-scale evaluation of exploration strategies.

  14. Regional paleoclimatic and stratigraphic implications of paleosols and fluvial/overbank architecture in the Morrison Formation (Upper Jurassic), Western Interior, USA

    NASA Astrophysics Data System (ADS)

    Demko, Timothy M.; Currie, Brian S.; Nicoll, Kathleen A.

    2004-05-01

    Paleosols in the Morrison Formation (Upper Jurassic) from the Western Interior and Colorado Plateau regions occur in fluvial/overbank and marginal-lacustrine depositional facies associated with aggradational settings, and at sequence-bounding unconformities that mark divisions between major aggradational and degradational successions. Pedogenic features within these horizons preserve important contextual information about the local and regional paleoclimate and paleoenvironment in which the soils formed. Floodplain and lake-margin paleosols show evidence that most of the Morrison basin was characterized by a semi-arid to tropical wet-dry paleoclimate with fluctuating groundwater conditions, a low precipitation to evaporation ratio, and weak to moderately seasonal precipitation. Paleosol ichnofauna show evidence of a diverse and opportunistic flora and fauna that exploited changing conditions and existing nutrient and moisture regimes. Changes in paleosol type and degree of development over the basin indicate the overall regional paleoclimate was drier in the western and southern portions of the basin. Vertical trends indicate paleoclimatic conditions over the basin became steadily more humid through time. Laterally continuous, well-developed, deeply weathered paleosols formed during times of little or no deposition and mark regional unconformities. The paleosols at these sequence-bounding unconformities serve as useful regional stratigraphic markers to trace genetic packages across the Morrison depositional basin and to determine regional accommodation trends.

  15. Improved oil recovery in fluvial dominated deltaic reservoirs of Kansas - near - term. Technical progress report, June 17, 1994--June 17, 1995

    SciTech Connect

    NONE

    1996-07-01

    Common oil field problems exist in fluvial dominated deltaic reservoirs in Kansas. The problems are poor waterflood sweep and lack of reservoir management. The poor waterflood sweep efficiency is due to (1) reservoir heterogeneity, (2) channeling of injected water through high permeability zones or fractures, and (3) clogging of water injection wells with solids as a result of poor water quality. In many instances the lack of reservoir management is due to lack of (1) data collection and organization, (2) integrated analysis of existing data by geological and engineering personnel, and (3) identification of optimum recovery techniques. Two demonstration sites operated by different independent oil operators are involved in the project. The Stewart Field (on the latter stage of primary production) is located in Finney County, Kansas, and was operated by Sharon Resources, Inc. and is now operated by North American Resources Company. The Nelson Lease (an existing waterflood) is located in Allen County, Kansas, in the N.E. Savonburg Field and is operated by James E. Russell Petroleum, Inc. The objective is to increase recovery efficiency and economics in these type of reservoirs. The technologies being applied to increase waterflood sweep efficiency are (1) in situ permeability modification treatments, (2) infill drilling, (3) pattern changes, and (4) air flotation to improve water quality. The technologies being applied to improve reservoir management are (1) database development, (2) reservoir simulation, (3) transient testing, (4) database management, and (5) integrated geological and engineering analysis.

  16. Variability of fluvial sediment supply to the Laptev Sea continental margin during Late Weichselian to Holocene times: implications from clay-mineral records

    NASA Astrophysics Data System (ADS)

    Müller, Claudia; Stein, Ruediger

    2000-08-01

    Three sediment cores from the Laptev Sea continental margin were investigated for their clay mineralogy by X-ray diffraction to study the fluvial sediment supply since the late Weichselian. In the study area, the clay-mineral composition of surface sediments is characterized by distinct regional variations. The source area for smectite in the eastern Eurasian Basin is the Putoran Plateau drained by the Khatanga and Yenisei rivers. Currents caused by river discharge and the inflow of Atlantic water masses along the Eurasian continental margin are responsible for sediment distribution. In the sediment cores, smectite and illite contents show an opposite trend which mainly results from variable smectite supply. During MIS 2 the amount of smectite on the Laptev Sea continental margin never exceeds 10 rel.%. Probably, reduced river discharge and the lowered sea level during MIS 2 caused a decreased sediment supply to the Laptev Sea. Additionally, the Putoran Plateau was covered by an ice sheet during the Late Weichselian preventing the erosion of smectite-rich soils. In contrast, maximum smectite contents (up to 30 rel.%) in Holocene sediments result from increased sediment input by the Khatanga River and from the Kara Sea through the Vilkitsky Strait and via St. Anna Trough into the western Laptev Sea.

  17. Spatiotemporal analysis of air conditions as a tool for the environmental management of a show cave (Cueva del Agua, Spain)

    NASA Astrophysics Data System (ADS)

    Fernandez-Cortes, A.; Calaforra, J. M.; Sanchez-Martos, F.

    We recorded the air temperature and carbon dioxide concentration within the Cueva del Agua, a cave in Spain, under natural conditions prior to the cave being opened to tourists. Geostatistical tools are useful techniques for characterizing microclimate parameters with the aim of adopting measures to ensure the conservation and sound environmental management of tourist caves. We modelled the spatial distribution of these microclimatic parameters over an annual cycle using iterative residual kriging, revealing the stratification of air related to the cave's topography. Replenishment of the cave air is activated by convective circulation that accompanies the development of inversions in the thermal gradient of the air. Comparison of the spatial distribution of each microclimatic parameter over time enables us to characterize the exchange of air between the cave interior and the outside, as well as identify potential areas that could be opened to tourists and determine suitable visiting schedules.

  18. Prevalence and Correlates of ‘Agua Celeste’ Use among Female Sex Workers who Inject Drugs in Ciudad Juarez, Mexico

    PubMed Central

    Morris, Meghan D.; Case, Patricia; Robertson, Angela M.; Lozada, Remedios; Vera, Alicia; Clapp, John D.; Medina-Mora, Maria Elena; Strathdee, Steffanie A.

    2011-01-01

    Background Agua celeste, or “heavenly water,” is the street name for a sky-blue colored solvent reportedly inhaled or ingested to produce an intoxicating effect. Study aims were to (1) describe prevalence of Agua Celestse (AC) use, and (2) identify correlates of lifetime and recent use of AC use among female sex workers who also inject drugs (FSW-IDUs) in northern Mexico. Methods Between 2008 and 2010, baseline data from FSW-IDUs ? 18 years old living in Tijuana or Ciudad Juarez participating in a longitudinal behavioral intervention were analyzed using logistic regression. Results Among 623 FSW-IDUs (307 from Tijuana and 316 from Ciudad Juarez (CJ)), 166 (26%) reported ever using AC, all of whom lived in CJ. Among the CJ sample, lifetime prevalence of AC use was 53%, median age of first use was 16 years (IQR: 14–23), and 10% reported it as their first abused substance. Ever using AC was independently associated with ever being physically abused and younger age, and was marginally associated with initiating injection drug use and regular sex work at age eighteen or younger. Among those ever using AC, 70/166 (42.2%) reported using it within the last 6 months, which was independently associated with using drugs with clients before or during sex, being on the street more than 8 hours per day, and younger age. Discussion We observed considerable geographic variation in the use of AC in northern Mexico. Future studies exploring factors influencing use, its precise formulation(s), and its potential health effects are needed to guide prevention and treatment. PMID:21441001

  19. Stratigraphic architecture and morphostructures of a recent glacio-isostatically forced-regressive delta: implications in terms of proglacial fluvial dynamics, North Shore of the St-Lawrence Estuary, Québec, Canada

    NASA Astrophysics Data System (ADS)

    Dietrich, Pierre; Ghienne, Jean-François; Schuster, Mathieu; Lajeunesse, Patrick; Deschamps, Rémy; Nutz, Alexis; Roquin, Claude; Duringer, Philippe

    2015-04-01

    Proglacial deltaic systems provide information about ice margins evolution, related glacio-isostatic rebound and proglacial fluvial dynamic during ice-sheet retreat. Here, we document a case study based on the North Shore of the St-Lawrence Estuary, Québec, Canada, recording the recession of the Laurentide Ice Sheet after the Last Glacial Maximum (Upper Wisconsinian-Holocene). The entire deltaic succession is exposed throughout coastal cliffs and river-cut terraces. Field investigations involve sedimentary logs, 14C dating and the characterization of morphosedimentary structures in the hinterlands. The delta initiates around 11 kyr Cal BP during an ice-front stabilization. Marine invasion on isostatically flexured lowlands led to the development of the Goldthwait Sea that reached a marine limit at the present-day 140 m elevation. At this time, ice contact and glaciomarine sediments were emplaced at the mouth of the major structural valleys. The subsequent glacial retreat farther inland turned the structural valleys into fjords into which deltas develop. The rapid fulfilling of these depocenters by glaciogenic sediments led to the emergence and coalescence of the deltas on the open sea. Lower delta front deposits are made up of mud while sand-sized, turbiditic deposits including facies related to supercritical flows (chutes, cyclic steps) prevail in the upper reaches. The delta plain is composed of gravelly facies deposited by braided streams. The progradation of the proglacial deltaic complex was about 10 km (thickness > 100 m) in only 1000 years in the open coast setting while the sea-level fall due to the glacio-isostatic rebound was up to 10 cm/yrs. This system remains active until the melting of the ice margins out of the catchment area at 10 kyr Cal BP. Sedimentary suites associated with the later paraglacial evolution comprise nearshore sand wedge (spit platform) and foreshore complexes. Throughout the entire proglacial deltaic development, no major fluvial incision occurred in spite of significant rates of sea-level fall (50m/1000 yrs). This owes to a fluvial equilibrium profile steeper than the descending regressive shoreline trajectory mainly due to an important glaciogenic sediment supply. Alternatively, fluvial entrenchment actively arose as soon as the ice margins retreated out of the catchment area in a context enduring lesser rates of sea-level fall. Fluvial entrenchment processes are explored, including buffer/buttress incision processes and the key role of bedrock thresholds, rate of sea level-fall and the drawdown of the glaciogenic/paraglacial sediment supply.

  20. Investigating Holocene climatic zonation in North Tian Shan from fluvial terraces dating : a new Bayesian approach for cosmogenic 10Be/26Al age determination from depth profiles

    NASA Astrophysics Data System (ADS)

    Gayer, E.; Narteau, C.; Holschneider, M.; Barrier, L.; van der Woerd, J.; Guerit, L.; Lajeunesse, E.; Métivier, F.

    2013-12-01

    Understanding mechanisms that modify landscapes requires quantification of the rates at which landscapes respond to tectonic and climatic signals. Because fluvial terraces can provide important information on rates of river incision and because factors that may cause river incision include processes resulting from variations in climate (increase in precipitation and discharge, decrease in the river's sediment load, spread of vegetation cover etc...), the use of fluvial terraces dating (using 14C, OSL, cosmogenic 10Be-26Al ages) has grown rapidly in the recent years. In order to investigate Holocene climate change along the northern flank of Tian Shan we estimated ages and incision rates of the Urumqi River alluvial fan using cosmogenic 10Be and 26Al depth profiles. The Urumqi River is located on the East end of the Tian Shan range. Samples come from the top of its alluvial fan (T1) and from two terraces (T2 and T3) that were cut and abandoned during river downcutting. Quartz gravels and sands have been sampled along three depth profiles below 30 to 40cm of loess deposits. 10Be and 26Al concentrations profiles allowed us to calculate two different ages for each terrace, one taking into account the loess cover that masks cosmic rays the other one with no loess cover. Initial results indicate that the alluvial fan of the Urumqi River was abandoned between 8.3×1.6Ka and 5.8×1.1Ka. T2 was abandoned between 3.1×0.6Ka and 2.3×0.4Ka, while the age of terrace T3 (2m above the present river bed) is present day. From these cosmogenic ages we calculate two different incision rates of 4-6mm/yr (from T1 to T2) and 7-10mm/yr (from T2 to T3) suggesting a strong modification of the Urumqi River erosional capacity around ~3Ka. The incision of the Urumqi alluvial fan at ~8.3-5.8Ka can't be directly linked to the post Younger Dryas deglaciation like it is suggested by OSL dating (10-11Ka) for the Kuitun River at the West end of the Tian Shan (Poisson and Avouac 2004). However this discrepancy in the timing of alluvial fans incision (between the East and West part of the range) can be related to a difference in the nature of the glaciers feeding the different watersheds. Since the type of glacier is strongly linked to local climate, this discrepancy suggests an East-West climatic zonation during Holocene, close to the one observed today. Finally, a new approach, using Bayesian statistics, is currently under development and will be used to better constrain the cosmogenic 10Be and 26Al ages and their uncertainties calculated from the depth profiles. Poisson B, Avouac JP, Holocene hydrological changes inferred from alluvial stream entrenchment in North Tian Shan (Northwestern China), Journal of Geology, 112, 231-249 (2004)

  1. Non - continuous archive of climatic fluctuations of various order in slope and fluvial systems of C-E Europe during upper Quaternary

    NASA Astrophysics Data System (ADS)

    Starkel, Leszek

    2015-04-01

    On the continents the continuous deposition reflecting environmental changes is recorded only in sedimentary basins surrounded by barriers protecting them against supply of mineral matter from outside. Most frequently we analyse non- continuous sedimentation in vertical profile and the particular layers, units or complexes may represent time intervals of various time length starting from effect of heavy downpour to multiannual member formed by solifluction or dune and to soil profile created across millennia. The sequences of sediments have many breaks caused by erosion, which also may represent time units of various duration. To compare these time fragments recorded in particular profiles with continuous ice, sea and lake sequencies we should date these deposits and study them in the complex systems like longitudinal profile of slope or river valley. The reconstruction of degradation and deposition in the profile may help to fill the gap and put all factors in one sequence. The sequence of loess alternated with fossil soils or the interfingering of deluvial and congelifluction layers in slope profile reflect various length of climatic fluctuation. The correlation of erosional features upstream and depositional fills downstream help to reconstruct not only glacial-interglacial climatic variation but also recognise individual extreme events and their clusterings. The detail correlation of various localities and greater regions lead to the conclusions about the leading role of changes in temperature during cold stages in C-E Europe and leading role of humidity and its extreme events during the Holocene. The mechanism of these events and their clusters recorded at present time may be reconstructed in the deposits and erosional forms inherited from the past. On this way the reconstruction of climatic fluctuation is much more deeper and shows also spatial diversity. The discussed problems will be illustrated by examples of fluvial and slope sediments from several localities investigated in detail.

  2. The responses of fluvial geochemical signatures to runoff and the inferences of possible flow paths for small mountainous rivers in Taiwan

    NASA Astrophysics Data System (ADS)

    Lee, Tsung-Yu; Hong, Nien-Ming; Shih, Yu-Ting; Huang, -Chuang, Jr.; Kao, Shuh-Ji

    2015-04-01

    Catchment systems are hydrologically complex having varied flow paths which respectively contribute to the streamflow in different hydrological conditions and control fluvial geochemical signatures. In this study, a one-year detailed time series of streamwater chemistry, including non-typhoon and typhoon samples, was monitored in two watersheds, i.e. with and without cultivation, in central Taiwan. In addition, rainwater, soil water and well water were supplemented to discover the mechanism of solute transport and to identify the possible flow paths. The concentration of fluoride, chloride, sulfate, magnesium, potassium, calcium, strontium, silicon, and barium of all the water samples were measured. Besides, end member mixing analysis (EMMA) was applied to link the streamwater chemistry to the hydrological processes in such region. Three major flow paths, i.e. groundwater, subsurface flow (soil water), and surface runoff, were identified. Surface runoff actually influences the streamwater chemistry via two forms. One is access rainwater having similar chemistry to rainwater and diluting streamwater chemistry. The other is the eroded soil particle attached with particulate-associated solutes enhancing streamwater chemistry. The results of EMMA show that the streamwater chemistry of non-typhoon and typhoon samples could be mostly explained by a binary mixing between groundwater and soil water and between soil water and surface erosion, respectively. The missing end member reveals the great variability in the relative contributions to streamflow from these three major water masses. Fertilizer labels the soil water in the farm making soil water end member more identifiable. More comprehensive end member samples are suggested to fully understand the flow paths for subtropical small mountainous rivers.

  3. Post waterflood CO{sub 2} miscible flood in light oil, fluvial-dominated deltaic reservoir. Annual report, October 1, 1993--September 30, 1994

    SciTech Connect

    Bou-Mikael, S.

    1995-07-01

    Texaco Exploration and Production Inc. (TEPI) and the U.S. Department of Energy (DOE) entered into a cost sharing cooperative agreement to conduct an Enhanced Oil Recovery demonstration project at Port Neches. The field is located in Orange County near Beaumont, Texas. The project will demonstrate the effectiveness of the CO{sub 2}, miscible process in Fluvial Dominated Deltaic reservoirs. It will also evaluate the use of horizontal CO{sub 2} injection wells to improve the overall sweep efficiency. A data base of FDD reservoirs for the gulf coast region will be developed by LSU, using a screening model developed by Texaco Research Center in Houston. Finally, the results and the information gained from this project will be disseminated throughout the oil industry via a series of SPE papers and industry open forums. Reservoir characterization efforts for the Marginulina sand, are in progress utilizing conventional and advanced technologies including 3-D seismic. Sidewall and conventional. cores were cut and analyzed, lab tests were conducted on reservoir fluids, reservoir BHP pressure and reservoir voidage were monitored as shown. Texaco is utilizing the above data to develop a Stratamodel to best describe and characterize the reservoir and to use it as an input for the compositional simulator. The current compositional model is being revised to integrate the new data from the 3-D seismic and field performance under CO{sub 2} injection, to ultimately develop an accurate economic model. All facilities work has been completed and placed in service including the CO{sub 2} pipeline and metering equipment, CO{sub 2} injection and production equipment, water injection equipment, well work and injection/production lines. The horizontal injection well was drilled and completed on January 15, 1994. CO{sub 2} purchases from Cardox continue at an average rate of 3600 MCFD. The CO{sub 2} is being injected at line pressure of 1350 psi.

  4. Stratigraphy and Reservoir-analog Modeling of Upper Miocene Shallow-water and Deep-water Carbonate Deposits: Agua Amarga Basin, Southeast Spain

    E-print Network

    Dvoretsky, Rachel Ana

    2009-03-10

    the basin-wide stratigraphic characterization and 3-D reservoir-analog modeling of upper Miocene carbonate deposits in the Agua Amarga basin, Cabo de Gata volcanic province, southeast Spain. In the basin, paleotopography and relative fluctuations in sea... on the platform and basin sedimentation. INTRODUCTION Upper Miocene carbonate exposures throughout the Cabo de Gata volcanic province in SE Spain serve as the basis for multiple studies on the depositional history, lithofacies architecture, and sequence...

  5. Assessment of Karst Spring Features in a typical Mediterranean fluvial landscape with an Interdisciplinary Investigation nased on Radon-222 as an Environmental Indicator. The case study of the Bussento River basin (Campania region, Southern Italy).

    NASA Astrophysics Data System (ADS)

    Cuomo, A.; Guadagnuolo, D.; Guida, D.; Guida, M.; Knoeller, K.; Schubert, M.; Siervo, V.

    2012-04-01

    Karst aquifers provide 25% of the overall drinking water resources to the world's population and sustain aquatic life in most fluvial systems, providing several ecological services to human beings, although, because of their complex links between surface and groundwater, turn out to be very vulnerable to contamination and pollution. Hydrological assessment of karst systems reveals to be extremely complex and difficult and requires a stepwise multi-tracers approach. This work describes some of the most relevant findings obtained from the implementation of an interdisciplinary approach based on the use of Environmental Tracers, consisting of Naturally Occurring Radionuclides like Radon-222 (referred to as Radon), for the investigation of Groundwater/Surface water Interaction (GSI) processes in fluvial water bodies. In particular, Radon activity concentration measurement data having been collected from streamflow and instream springs during monthly field campaigns performed in a typical Mediterranean karst river basin: the Bussento river system (Campania region, Southern Italy). The general task has been to investigate the complex interactions and exchanges between streamflow and groundwater in a fluvial water body, at scales that are imperceptible to standard hydrological and hydraulic analyses. The Bussento River basin has been chosen as a study case for the following features of extreme relevance: Its location inside the Cilento and Vallo di Diano National Park, its inclusion of a WWF Nature Reserve, it represents a remarkable Drinking Water resource for the territory and last but not least its system includes Submarine Groundwater Discharges (SGD) to the Policastro Gulf. All these issues causes, therefore, that the management of its relevant water resources requires not only groundwater protection for domestic drinking use, but also riverine wildlife preservation and coastal water quality maintenance. As a support for hydro-geomorphological and hydrological modelling for planning tasks, in application of the European Water Framework Directive (EWFD), a Bussento River Monitoring System (BRMS) as been built, at basin, segment and reach scale. Experimental data about 222Rn activity concentrations, in addition to physical-chemical and streamflow rate, have been acquired and managed from BRMS selected stations, sampling the streamflow and inflow spring waters by means of the Radon-in-Air analyzer, RAD7, together with the Radon-in-water accessories, Radon Water Probe and RAD7H2O (DURRIDGE Co. Inc.), for continuous and batch sampling measurements, respectively. The analysis of the seasonal data trends from karst springs confirms the hydrogeological conceptual model, highlighting the complex behaviour of a multilevel groundwater circuits, the uppermost in caves, the middle in conduits and the lowermost in fracture network, corresponding to the differentiated recharge types in the fluvial-karst hydro-geomorphological system. Please fill in your abstract text.

  6. An assessment of Spain's Programa AGUA and its implications for sustainable water management in the province of Almería, southeast Spain.

    PubMed

    Downward, Stuart R; Taylor, Ros

    2007-01-01

    Spain's Programa AGUA was proposed in 2004 as a replacement for the Spanish National Hydrological Plan and represented a fundamental policy shift in national water management from large inter-basin water transfers to a commitment to desalination. Twenty-one desalination facilities are planned for six provinces on the Spanish Mediterranean coast to supplement their water needs. These include the province of Almería that for the last 30 years has endured a net water abstraction overdraft leading to serious reservoir depletion and groundwater imbalances. Rising water use is a result of increasing demand to support irrigated agriculture (e.g. greenhouse horticulture) and for domestic needs (e.g. rapid urban growth and tourism development), which has led observers to question Almería's long-term water sustainability. Desalinated water alone is unlikely to be sufficient to make up these water deficits and water-users will have to accept a move to full-price water recovery by 2010 under the European Union (EU) Water Framework Directive of which Spain is a signatory. Anticipated water efficiencies resulting from higher water tariffs, increasing water reuse and water infrastructure improvements (including inter-basin transfers), in conjunction with increasing use of desalinated water, are expected to address the province's current water overdraft. However, Almería will need to balance its planned initiatives against long-term estimates of projected agricultural and domestic development and the environmental consequences of adopting a desalination-supported water future. PMID:16574308

  7. Limitations of Fluvial Analogs for the Dynamical Interpretation of Submarine Channel Systems: a Physical Modeling Case Study of Leveed Channel Formation.

    NASA Astrophysics Data System (ADS)

    Rowland, J. C.; Hilley, G. E.; Fildani, A.

    2008-12-01

    Inferring process from morphology and architectures is commonly used in the interpretation of the dynamics of depositional submarine systems based on seismic and outcrop observations. The linking form to process often requires that an observed morphology is produced by a unique set of dynamics. Accordingly, submarine channel dynamics are often inferred from observed channel form through analogy with subaerial fluvial systems. For example, prograding deltaic channels bear striking morphological resemblance to leveed submarine channels that traverse continental slopes and submarine basins. However, given the different physical circumstances of these two environments, it is unclear how analogous are the relationships between channel form and flow dynamics in these two systems. To test whether the jet morphodynamics responsible for deltaic channel formation were applicable to submarine settings, we conducted a series of physical experiments in which sediment-laden flows that were considerably denser than the surrounding fluids were fully submerged in the less dense fluid. Given these dynamical conditions, we were unable to find a set of experimental conditions under which a pair of bounding levees could develop from a non-eroding sediment- laden density current undergoing sudden unconfinement. At supercritical bulk Richardson numbers, high rates of entrainment of the surrounding fluid into the sediment-laden flow led to rapid current deceleration and deposition of sediment along the axis of the flow. As bulk Richardson numbers increased, fluid entrainment decreased, allowing the current to flow further into the basin. Simultaneously, however, the rate at which the current collapsed laterally increased and as a result depositional patterns transitioned from one in which sediment was deposited parallel to the margins of the flow outlet to one in which sediment was radially distributed. As the denser flows collapsed, sediment was more broadly distributed, and consequently, relief of the deposited material was lower than observed for deposits produced by low Richardson number flows. Depositional patterns produced by dense flows differ significantly from those produced by the jet-like processes that govern deposition by deltaic channels, highlighting the fact that while such forms within subaerial and submarine environments may be similar, the underlying dynamics may be quite different. Our inability to produce self-organizing channel-levee systems for dense, depositional flows leads us to speculate that construction of leveed channels in the submarine environment may first require bed incision to provide partial confinement of the current.

  8. Performance Evaluation of Four DEM-Based Fluvial Terrace Mapping Methods Across Variable Geomorphic Settings: Application to the Sheepscot River Watershed, Maine

    NASA Astrophysics Data System (ADS)

    Hopkins, A. J.; Snyder, N. P.

    2014-12-01

    Fluvial terraces are utilized in geomorphic studies as recorders of land-use, climate, and tectonic history. Advances in digital topographic data, such as high-resolution digital elevation models (DEMs) derived from airborne lidar surveys, has promoted the development of several methods used to extract terraces from DEMs based on their characteristic morphology. The post-glacial landscape of the Sheepscot River watershed, Maine, where strath and fill terraces are present and record Pleistocene deglaciation, Holocene eustatic forcing, and Anthropocene land-use change, was selected to implement a comparison between terrace mapping methodologies. At four study sites within the watershed, terraces were manually mapped to facilitate the comparison between fully and semi-automated DEM-based mapping procedures, including: (1) edge detection functions in Matlab, (2) feature classification algorithms developed by Wood (1996), (3) spatial relationships between interpreted terraces and surrounding topography (Walter et al., 2007), and (4) the TerEx terrace mapping toolbox developed by Stout and Belmont (2014). Each method was evaluated based on its accuracy and ease of implementation. The four study sites have varying longitudinal slope (0.1% - 5%), channel width (<5 m - 30 m), relief in surrounding landscape (15 m - 75 m), type and density of surrounding land use, and mapped surficial geologic units. In general, all methods overestimate terrace areas (average predicted area 136% of the manually defined area). Surrounding topographic relief appears to exert the greatest control on mapping accuracy, with the most accurate results (92% of terrace area mapped by Walter et al., 2007 method) achieved where the river valley was most confined by adjacent hillslopes. Accuracy decreased for study sites surrounded by a low-relief landscape, with the most accurate results achieved by the TerEx toolbox (Stout and Belmont, 2014; predicted areas were 45% and 89% of manual delineations). Our work informs future studies by highlighting the strengths and drawbacks of each method tested and by making recommendations for the types of geomorphic settings where each is most appropriate. The tested algorithms represent powerful new ways to analyze landscape history over large regions using high-resolution, lidar DEMs.

  9. Multi-temporal topographic models in fluvial systems: are accuracies enough to change the temporal and spatial scales of our studies?

    NASA Astrophysics Data System (ADS)

    Vericat, Damià; Ramos, Ester; Brasington, James; Muñoz, Efrén; Béjar, María; Gibbins, Chris; Batalla, Ramon J.; Tena, Álvaro; Smith, Mark; Wheaton, Joe

    2015-04-01

    Recent advances in topography are offering a set of opportunities that deserve a critical evaluation before being successfully applied. Terrestrial Laser Scanning opened a new world by offering the opportunity to obtain topographic models at unprecedented resolutions. The time involved in data acquisition, although has substantially improved by means of fast scanners and new mobile platforms, limited the spatial and temporal scales in which such technique could be applied. Automatic Digital Photogrammetry or Structure from Motion is now offering a new set of opportunities and challenges. This technique possesses the trilogy a geomorphologist is looking to fully understand how landforms change and which are the main causes and consequences: speed, cost and resolution. But, a set of questions arise after all post-processing involved in these novel datasets: are accuracies enough to jump at large spatial scales? Can we repeat topographic surveys and depict small magnitude but relatively high frequent landform deformations overcoming the minimum level of detection of our comparisons? In this paper we present some of the preliminary results obtained in the background of MorphSed (www.morphsed.es). Morphsed is analysing the morpho-sedimentary dynamics of a fluvial system at multiple temporal scales. Multi-event topographic models (DEMs) are obtained by means of Structure from Motion using close range aerial photography obtained in a 12-km channel reach of the wandering Upper River Cinca (Southern Pyrenees, Iberian Peninsula). Topographic channel changes are critically analysed based on the quality of the developed models. DEMs obtained at different periods are compared (DoD). Two general comparisons are performed: (a) comparison of topographic models obtained before and after low magnitude channel changes, and (b) comparison of models acquired before and after major channel disturbances. Special attention is paid to the role of the ground control, data density and resolution. A spatial distributed minimum level of detection is estimated and the distributions of cells above and below these values are reviewed. DoDs are thresholded, the morphological budget calculated and results compared. Finally, some general rules to consider when our field-data acquisition design is being developed are presented.

  10. Holocene paleovegetation reconstructed from a fluvial sediment-paleosol sequence along the upper Alazani River (Caucasus region) using leaf-wax biomarkers - local vs. catchment information

    NASA Astrophysics Data System (ADS)

    Bliedtner, Marcel; Zech, Roland; von Suchodoletz, Hans

    2015-04-01

    Due to its small-scale pattern of different climatic and ecologic regions and a long-lasting history of human land-use since ca. 8 ka, the Caucasus region is of particular interest with regard to Holocene climatic and paleoenvironmental changes. However, there only exists a limited number of paleoenvironmental reconstructions from that region yet. This study aims at reconstructing Holocene vegetational and paleoenvironmental changes using leaf-wax n-alkanes, n-carboxylic acids and compound specific ?13C and ?D isotopes from a fluvial sediment-paleosol sequence along the upper Alazani River in eastern Georgia. Phases of sedimentation and pedogenesis between >8 until ca. 1.7 cal. ka BP reflect alternating periods of geomorphic stability (pedogenesis) with reduced flooding activity due to more arid conditions, and periods of geomorphic activity (sedimentation) with increased flooding and erosion in the humid catchment area due to enhanced precipitation. Thus, biomarkers derived from non-pedogenetic sediments should be mostly derived from the catchment area located in the southern Greater Caucasus Mountains, whereas due to pedogenetic accumulation of organic matter biomarkers derived from the (paleo-)soils should mostly show the local signal of the sampling site located in the piedmont area. Long-chain leaf wax-derived n-alkanes are present in all samples: Paleosols are mostly dominated by high contributions from grass vegetation (C31 and C33), indicating a local dominance of grass vegetation throughout the Holocene. This could be caused by relatively arid conditions and/or by agricultural use that is documented at this site by potsherds from ca. 8 cal. ka BP. Non-pedogenetic sediment layers show a higher abundance of grass-derived n-alkanes during the early Holocene and the Caucasian Holocene climate optimum around 5 cal. ka BP, whereas deciduous trees (C27 and C29) may have dominated after that period. However, it is not clear yet whether this vegetation change from grasses to deciduous trees in the catchment area of the Greater Caucasus Mountains is caused by climatic changes or by human activity. The n-carboxylic acids generally corroborate and complement the alkane data. Compound-specific isotope analyzes are currently in progress.

  11. Fluvial response to sudden input of pyroclastic sediments during the 2008-2009 eruption of the Chaitén Volcano (Chile): The role of logjams

    NASA Astrophysics Data System (ADS)

    Umazano, Aldo M.; Melchor, Ricardo N.; Bedatou, Emilio; Bellosi, Eduardo S.; Krause, Javier M.

    2014-10-01

    The rhyolitic Plinian eruption of the Chilean Chaitén Volcano, initiated on May 2, 2008, suddenly introduced abundant pyroclastic sediments in the Blanco River catchment area, which experienced important modifications. Before May 2, the river was characterised by gravelly and moderate to low-sinuosity channels crossing a vegetated and locally urbanised (Chaitén City) floodplain. This river, limited by steep and densely forested highlands, was connected with the Pacific Ocean via a tidally-influenced delta plain. After heavy rains in May 11-20, the river discharge increased and triggered several responses including logjam formation and breakage, crevassing, avulsion (and channel abandonment), changes in the pattern and dimensions of channels, and construction of a new delta plain area. In this context, the goals of this contribution were: i) to document the sedimentological processes within a detailed geomorphic framework and ii) to understand the influence of logjams on fluvial dynamics. Upstream of the logjam zone, the deposits are mostly composed of ash and lapilli with abundant palaeovolcanic (epiclastic) sediments, which were produced by dilute currents and debris flows. Downstream of the logjam zone, deposits are composed by ash and lapilli, both pumice-rich and lacking important participation of older (epiclastic) sediments. The abandoned and filled palaeochannel, and the proximal part of crevasse splays experienced transient dilute flows with variable sediment concentration and, subordinately, hyperconcentrated flows. The distal sectors of crevasse splays mostly record settling from suspension. At the delta plain, tephra transported by the Blanco River was mixed with older sediments by tide and wave action (dilute flows). We conclude that immediately after eruption, both geomorphic and sedimentary processes of the river were mainly controlled by a combination of high availability of incoherent pyroclastic sediments on steep slopes, abundant rains, large logs that jammed the river and huge areas of devastated forest. Logjams played an important role in the river response to the volcanic eruption; they were responsible of the marked compositional change recorded upstream and downstream of the logjam zone and its breakage resulted in downstream flooding and avulsion. The likelihood of formation of logjams in rivers draining forested volcanic areas should be considered in the evaluation of volcanic hazards related to Plinian eruptions.

  12. Fluvial dynamics of the Meuse-Rhine system at the SW-border of the Roer Valley Graben (Belgium-Netherlands) during the Early to Middle Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Beerten, Koen; Westerhoff, Wim E.; Menkovic, Armin

    2015-04-01

    The evolution of the Meuse-Rhine confluence area during the late Early and early Middle Pleistocene is still poorly understood. The key in unravelling the complex history of the confluence area during the time period mentioned is located along a segment of the southwestern bounding faults of the Roer Valley Graben, where the elevated (uplifted) Campine Plateau borders the subsiding graben. Traditionally, the central and eastern part of the plateau is thought to have been occupied by the Meuse (Zutendaal Formation) during some stages of the Early-Middle Pleistocene, while clear evidence is found for the presence of supposedly time-equivalent Rhine deposits (Sterksel Formation) in the graben (Gullentops et al., 2001). However, the stratigraphical relationship between both formations is very unclear. Here, we present results of detailed investigations of borehole cores distributed along the southwestern border of the graben that allow to develop a framework for the fluvial evolution in the area. New grain size, sedimentary petrology (microgravel) and pollen analyses are presented, and incorporated in the results of detailed mapping of the area that is based on borehole data from the subsurface databases of Flanders and the Netherlands. The time window of this study is set by pollen and heavy mineral data. The almost complete absence of pollen from heather and warm loving trees suggests a post-Bavelian age, while the absence of volcanic augite (Gullentops et al., 2001) suggests a pre-Elsterian age for the Rhine sediments. This limits most of the sedimentary record in that area to the Cromerian. The results show that initially, the Rhine deposited coarse-grained (mostly gravelly sand) material over large parts of the graben area, while sedimentation of the Meuse was restricted to the region south of the graben. In the lower part of the here studied sequence a fine-grained flood plain facies of the Rhine is preserved in the tectonically deeper part of the SW graben area. Deposition of Rhine sediments was interrupted when the Meuse prograded deeper into the graben, as can be inferred from gravel petrology and grain size. The sequence ends with another episode of deposition by the Rhine, after which the graben area evolves into a local sedimentation system (Boxtel Formation). The pollen spectra suggest that sedimentation took place during stadials and interstadials, while interglacial sediments are not preserved. We conclude that the poor development of Cromerian Meuse sediments in the Roer Valley Graben is probably due to a drastic decrease of river competence and capacity when it leaves the Campine block and enters the flat graben floor. There, the competence of the sand-dominated Rhine is insufficient to transport the (very) coarse gravels of the Meuse.

  13. Holocene to contemporary fluvial sediment fluxes and budgets of two glacier-fed valley-fjord systems in the Nordfjord area, western Norway

    NASA Astrophysics Data System (ADS)

    Liermann, S.; Beylich, A. A.; Hansen, L.

    2012-04-01

    This PhD project is part of the NFR funded Norwegian Individual Project within the ESF SedyMONT (Timescales of sediment dynamics, climate and topographic change in mountain landscapes) TOPO-EUROPE program. Two neighboring glacier-fed valley-fjord systems (Erdalen & Bødalen) with a different topographic inheritance from Pleistocene glaciations are compared. It is of special interest how the different valley morphometries have influenced Holocene to contemporary sediment fluxes and budgets. To understand the spatial and temporal sediment flux variability during the Holocene the main focus lays on i) quantification and analysis of storage element volumes for estimation of Holocene sedimentation rates and sediment yields, ii) analysis of the spatial and temporal sediment flux variability, iii) analysis of the linkages between sediment transfer and storage, iv) analysis of controlling factors for postglacial, sub-recent and contemporary sediment fluxes and v) construction of Holocene to contemporary sediment budgets for Erdalen and Bødalen. The analysis of sedimentary fluxes and budgets as well as their controls at different timescales (Holocene to contemporary) is a basis for the assessment of complex landscape responses of Holocene to recent changes in temperature, precipitation and runoff. For constructing sediment budgets at a small-catchment scale (50-100 km2) it is necessary to integrate the temporal and spatial variations of supply of material from sediment sources, sediment transport and storage and to identify, how far the different system components are coupled to each other. Both valleys are instrumented with a year-round monitoring system (runoff, suspended and solute transport) for analyzing fluvial sediment fluxes. The results enable to link sediment transport and runoff (events) and the spatial and temporal variability of sediment transport processes. In addition, glacier sediment supply and its spatial variability in Erdalen and Bødalen is monitored and analyzed to look at its role for the entire sediment budget for the two valley-fjord-systems. Geophysical methods (Georadar, Geoseismic) are applied for calculation of the total valley infills and for interpretation of the stratigraphic architecture, with the goal to define the controlling factors for the postglacial sediment storage within the two glacially eroded valleys. Lake sediment investigations are focused on i) quantifying the contemporary sedimentation rates, ii) the role of proglacial lakes as sediment trap/temporary storage element within the sediment routing system and iii) the detection and analysis of sediment sources. Sediment cores are retrieved in the lake Sætrevatnet Bødalen as a representative example of the two valleys Erdalen and Bødalen.

  14. Stratigraphic architecture, bedload extraction, and mass balance of Holocene fluvial sediments in a tectonically subsiding basin within the Ganges-Brahmaputra River delta, Bangladesh

    NASA Astrophysics Data System (ADS)

    Sincavage, R.; Goodbred, S. L., Jr.; Pickering, J.; Wilson, C.; Paola, C.; Hossain, S.; Steckler, M. S.; Seeber, L.

    2014-12-01

    The Brahmaputra River occupied the tectonically active Sylhet Basin in eastern Bangladesh three times during the Holocene. With samples from more than 200 closely-spaced (3-5 km) boreholes, we take advantage of these discrete channel occupations and the high trapping efficiency of the subsiding basin to investigate dispersal of fluvial sediments. Experiment and theory suggest that depositional units transition from channels to lobes as transported sediment mass declines below ~30% of the total measured at the basin head. We test these ideas by reconstructing the geometry and grain size distributions of a large (30 m thick x 80 km wide) sand lobe formed during the mid-Holocene occupation (~7000-4000 years BP) of Sylhet Basin. Based on estimates of modern sediment discharge in the system, the volume of this sediment lobe is insufficient to account for the entire sediment budget. The smaller sediment volume is likely a consequence of reduced sediment discharge during a weakened monsoon. Additional sediment is likely to have also been routed out of the basin via an outlet located approximately along the modern Meghna River channel. Facies within Sylhet Basin can be characterized as stacked braidbelt sands in the proximal portion of the system, with isolated sand lenses further downstream, indicating a transition from a highly mobile braidbelt to a less mobile distributary system. The majority of bed load is extracted within a distance of ~150 km from the avulsion node, approximately coincident with the regional backwater reach of the Bengal Basin, suggesting a link between the hydraulic and "morphodynamic" backwater reaches of the system. Downstream fining is more rapid in sediments associated with the long-term occupation of Sylhet Basin, for which sediment is trapped over a relatively short distance within the sand wedge of central Sylhet Basin, than those from the early- and late-Holocene occupations, for which sediment is distributed over a longer path that follows the course of the Old Brahmaputra River. Fine-grained sediments preserved in the system do not display measureable downstream fining. The increased rate of sediment extraction in the eastern part of the basin is likely coupled with a subsidence maximum (~7 mm/year) associated with the foredeep of the Dauki thrust fault.

  15. Timing and Mode of Landscape Response to Glacial-Interglacial Climate Forcing From Fluvial Fill Terrace Sediments: Humahuaca Basin, E Cordillera, NW Argentina

    NASA Astrophysics Data System (ADS)

    Schildgen, T. F.; Robinson, R. A. J.; Savi, S.; Bookhagen, B.; Tofelde, S.; Strecker, M. R.

    2014-12-01

    Fluvial fill terraces provide a record of changes in sediment production and/or transport in response to external forcing. The N-S striking Humahuaca intermontane basin (Eastern Cordillera, NW Argentina) parallels the eastern margin of the Puna Plateau and is known for frequent landslides/debris flows during the wet season and protracted past wet periods. Fill terraces along tributaries (with 20-1100 km2 catchments) to the trunk stream are dated with OSL to between ~30 and 120 ka. Aggradation phases on the west side of the basin correlate with past wet periods, and those on the east side with dry periods. The difference may arise because the river-network geometry of eastern catchments promotes sediment storage, resulting in delayed sediment delivery to the trunk stream and/or a higher threshold to erosion and sediment transport. Cosmogenic nuclide (10Be) concentrations of sand (<0.7 cm) and pebbles (1-3 cm) reveal that in modern stream sediments, (1) denudation rates from sand (<0.1 mm/yr) overlap with bedrock erosion rates, (2) denudation rates from pebbles are 1.2 to 4x higher, which could reflect the importance of mass movements, and (3) eastern catchments yield lower rates. From wet-phase (west side) terraces, denudation rates are higher than those from modern streams, while highly scattered pebble denudation rates of 0.1-10 mm/yr may reflect an increased frequency of mass movements in past wetter periods. In contrast, dry-phase (east side) terrace pebble and sand denudation rates overlap with modern rates, 26Al/10Be ratios are low, and a sample from the sediment storage zone has a relatively high pebble denudation rate of 0.3 mm/yr. We interpret the patterns to imply that mass movements are triggered throughout the valley during wet climate phases and induce aggradation, but slow re-excavation of stored sediments from eastern catchments leads to increased 10Be concentrations and delayed sediment delivery to the main valley. Such behavior at an orogen scale could attenuate or mask landscape responses to climate forcing.

  16. Este estudio examina los factores demogrficos asociados con la deforestacin en el Par-que Nacional Sierra de Lacandn (PNSL), Guatemala, utilizando un anlisis de regresin

    E-print Network

    Lopez-Carr, David

    - que Nacional Sierra de Lacandón (PNSL), Guatemala, utilizando un análisis de regresión multinivel. Más. Palabras clave: usos del suelo, deforestación, crecimiento demográfico, regresión multini- vel, Guatemala análisis multinivel de población y deforestación en el Parque Nacional Sierra de Lacandón (Petén, Guatemala

  17. The scaling of fluvial landscapes

    NASA Astrophysics Data System (ADS)

    Birnir, Björn; Smith, Terence R.; Merchant, George E.

    2001-12-01

    The analysis of a family of physically based landscape models leads to the analysis of two stochastic processes that seem to determine the shape and structure of river basins. The partial differential equation determine the scaling invariances of the landscape through these processes. The models bridge the gap between the stochastic and deterministic approach to landscape evolution because they produce noise by sediment divergences seeded by instabilities in the water flow. The first process is a channelization process corresponding to Brownian motion of the initial slopes. It is driven by white noise and characterized by the spatial roughness coefficient of 0.5. The second process, driven by colored noise, is a maturation process where the landscape moves closer to a mature landscape determined by separable solutions. This process is characterized by the spatial roughness coefficient of 0.75 and is analogous to an interface driven through random media with quenched noise. The values of the two scaling exponents, which are interpreted as reflecting universal, but distinct, physical mechanisms involving diffusion driven by noise, correspond well with field measurements from areas for which the advective sediment transport processes of our models are applicable. Various other scaling laws, such as Hack's law and the law of exceedence probabilities, are shown to result from the two scalings, and Horton's laws for a river network are derived from the first one.

  18. The fluvial history of Mars.

    PubMed

    Carr, Michael H

    2012-05-13

    River channels and valleys have been observed on several planetary bodies in addition to the Earth. Long sinuous valleys on Venus, our Moon and Jupiter's moon Io are clearly formed by lava, and branching valleys on Saturn's moon Titan may be forming today by rivers of methane. But by far the most dissected body in our Solar System apart from the Earth is Mars. Branching valleys that in plan resemble terrestrial river valleys are common throughout the most ancient landscapes preserved on the planet. Accompanying the valleys are the remains of other indicators of erosion and deposition, such as deltas, alluvial fans and lake beds. There is little reason to doubt that water was the erosive agent and that early in Mars' history, climatic conditions were very different from the present cold conditions and such that, at least episodically, water could flow across the surface. In addition to the branching valley networks, there are large flood features, termed outflow channels. These are similar to, but dwarf, the largest terrestrial flood channels. The consensus is that these channels were also cut by water although there are other possibilities. The outflow channels mostly postdate the valley networks, although most are still very ancient. They appear to have formed at a time when surface conditions were similar to those that prevail today. There is evidence that glacial activity has modified some of the water-worn valleys, particularly in the 30-50° latitude belts, and ice may also be implicated in the formation of geologically recent, seemingly water-worn gullies on steep slopes. Mars also has had a long volcanic history, and long, sinuous lava channels similar to those on the Moon and Venus are common on and around the large volcanoes. These will not, however, be discussed further; the emphasis here is on the effects of running water on the evolution of the surface. PMID:22474681

  19. Cascade model for fluvial geomorphology

    NASA Technical Reports Server (NTRS)

    Newman, W. I.; Turcotte, D. L.

    1990-01-01

    Erosional landscapes are generally scale invariant and fractal. Spectral studies provide quantitative confirmation of this statement. Linear theories of erosion will not generate scale-invariant topography. In order to explain the fractal behavior of landscapes a modified Fourier series has been introduced that is the basis for a renormalization approach. A nonlinear dynamical model has been introduced for the decay of the modified Fourier series coefficients that yield a fractal spectra. It is argued that a physical basis for this approach is that a fractal (or nearly fractal) distribution of storms (floods) continually renews erosional features on all scales.

  20. A consistent magnetic polarity stratigraphy of late Neogene to Quaternary fluvial sediments from the Heidelberg Basin (Germany): A new time frame for the Plio-Pleistocene palaeoclimatic evolution of the Rhine Basin

    NASA Astrophysics Data System (ADS)

    Scheidt, Stephanie; Hambach, Ulrich; Rolf, Christian

    2015-04-01

    This work presents the results of a magnetostratigraphic survey performed on 1150 m of core material from three sites within the Heidelberg Basin. The cores intersect one of the thickest continuous accumulations of Plio-Pleistocene fluvial sediments in western Central Europe. The resultant magnetic polarity stratigraphy includes every Quaternary polarity chron, thereby providing constant age constraint down to the Gauss-Matuyama Boundary (2.58 Ma). Older deposits cannot be unequivocally dated; instead, various age-depth models are discussed. We base our chronostratigraphic interpretation of the successions tentatively on three assumptions. A) The accommodation was almost constant over time. B) Hiatuses in the duration of subchrons (on the order of 0.2 Myr) may occur, and the actual step-like age-depth relationship is best depicted as a smooth curve with almost constant slope. C) Long chrons and subchrons have a higher preservation potential than shorter polarity intervals. The stratigraphic scenarios with the highest probability - based upon our three assumptions - lead to minimum ages of > 5.235 Ma and > 4.187 Ma for the oldest parts of the Viernheim and Heidelberg cores, respectively. Consequently, this study provides the first consistent magnetic polarity stratigraphy for quasi-continuous sequences of late Neogene to Quaternary fluvial sediments in the Rhine Basin and generally in western central Europe. This methodologically independent chronostratigraphy supplies an urgently required temporal model for on-going tectonic and sedimentological studies and the reconstruction of the palaeoclimate since the Pliocene in this part of Europe.

  1. Overview of the influence of syn-sedimentary tectonics and palaeo-fluvial systems on coal seam and sand body characteristics in the Westphalian C strata, Campine Basin, Belgium

    USGS Publications Warehouse

    Dreesen, Roland; Bossiroy, Dominique; Dusar, Michiel; Flores, R.M.; Verkaeren, Paul

    1995-01-01

    The Westphalian C strata found in the northeastern part of the former Belgian coal district (Campine Basin), which is part of an extensive northwest European paralic coal basin, are considered. The thickness and lateral continuity of the Westphalian C coal seams vary considerably stratigraphically and areally. Sedimentological facies analysis of borehole cores indicates that the deposition of Westphalian C coal-bearing strata was controlled by fluvial depositional systems whose architectures were ruled by local subsidence rates. The local subsidence rates may be related to major faults, which were intermittently reactivated during deposition. Lateral changes in coal seam groups are also reflected by marked variations of their seismic signatures. Westphalian C fluvial depositional systems include moderate to low sinuosity braided and anastomosed river systems. Stable tectonic conditions on upthrown, fault-bounded platforms favoured deposition by braided rivers and the associated development of relatively thick, laterally continuous coal seams in raised mires. In contrast, rapidly subsiding downthrown fault blocks favoured aggradation, probably by anastomosed rivers and the development of relatively thin, highly discontinuous coal seams in topogenous mires.

  2. Investigating how fundamental parameters of XRF sample preparation and analysis affect the observed elemental concentration: an experiment using fluvial sediment from Sabah, Borneo.

    NASA Astrophysics Data System (ADS)

    Higton, Sam; Walsh, Rory

    2015-04-01

    X-Ray Fluorescence (XRF) is an important technique for measuring the concentrations of geochemical elements and inorganic contaminants adsorbed to sediments as an input to sediment tracing methods used to evaluate sediment transport dynamics in river catchments. In addition to traditional laboratory-based XRF instruments, the advent of increasingly advanced portable handheld XRF devices now mean that samples of fluvial sediment can be analysed in the field or in the laboratory following appropriate sample preparation procedures. There are limitations and sources of error associated with XRF sample preparation and analysis, however. It is therefore important to understand how fundamental parameters involved in sample preparation and analysis, such as sample compression and measurement exposure duration, affect observed variability in measurement results. Such considerations become important if the resulting measurement variability is high relative to the natural variability in element concentrations at a sample site. This paper deployed a simple experimental design to assess the impacts of varying a number of sample preparation and XRF analysis parameters on recorded measurements of elemental concentrations of the fine fraction (<63um) of bed-sediment samples. Specifically the study compared observed elemental concentrations measured using a Rigaku NEX-CG laboratory machine versus a handheld Niton XL3t-900 XRF elemental analyser. Helium purging was used on both machines to enable measurement of lighter geochemical elements. Sediment sub-samples were taken from a larger homogenised sample from a sediment core taken from an in-channel lateral bench deposit of the Brantian river in Sabah, Borneo; the core site is being used for research into multi-proxy sediment fingerprinting as part of the Stability of Altered Forest Ecosystems (SAFE) project. Some fundamental sample preparation procedures consistent with US EPA Method 6200 were applied to all sediment samples in order to explore key variables of interest. All sediment samples were air-dried to constant weight and sample quantity was sufficient to satisfy the assumption of 'infinite thickness' of sample. Standard plastic sample cups were used for both the Rigaku laboratory machine and the Niton portable XRF machine. A computer-controlled desktop laboratory stand was used in conjunction with the Niton handheld XRF analyser to ensure consistent repeated measurements. Parameters investigated related to sample preparation included consistent mechanical compression of samples within the sample cup and film thickness. Parameters investigated related to XRF analysis included the XRF machine selected and measurement exposure duration. As XRF is a non-destructive technique, wherever possible the same sample material was used to test different parameters, so as to reduce variations due to the heterogeneous nature of sediment. Observed XRF measurements demonstrate how the precision and relative accuracy of elemental concentrations of sediment can be affected by the XRF analyser selected as well as fundamental parameters of sample preparation and analysis procedure. This has implications for studies where comparability and repeatability of measurements is important. Furthermore, the heterogeneous nature of sediments over small spatial scales means that it is important to understand the levels of variability in elemental concentrations resulting from variations in sample preparation and analysis procedures.

  3. Linkages of fluvial terrace formation and geometry to Milankovitch-scale climate change revealed by the chronostratigraphy of the Colorado River above Moab, UT, and regional correlations

    NASA Astrophysics Data System (ADS)

    Jochems, A. P.; Pederson, J. L.

    2012-12-01

    Fluvial terraces are important markers that contain information about incision, deformation, and climate change in a given landscape. However, our poor understanding of the links between climate drivers and the processes behind terrace formation renders them an imprecise tool. Unresolved issues include the influence of changes in hydrology versus sediment supply in controlling incision or sedimentation, whether terraces truly can be time-correlated across a large watershed or whether this is confounded by transient sediment signals, and the process link between strath/fill terrace form and climate, tectonic, or local valley geometry controls. In terms of the latter issue, terrace type is commonly associated with climate or tectonic controls, and it has been suggested that fill terraces tend to form in bedrock-restricted reaches and strath terraces in broader valleys. We address these problems through detailed chronostratigraphy of Colorado River terraces upstream of Moab, UT, and correlations to similarly well-constrained records near Green River, UT, and eastern Grand Canyon. Along the Colorado profile upstream of Moab, there are four traceable late Pleistocene mainstem terraces we designate as M2, M3y (younger), M3, and M4. Optically stimulated luminescence (OSL) ages indicate sedimentation at 25-20 ka, 50-40 ka, 75-60 ka, and 115-85 ka, respectively, for these deposits. Importantly, results indicate synchronous timing of terrace formation across the Colorado Plateau, ruling out transient sediment signals as a factor. Sedimentation of the M2 and M3 occur during the build-up to and height of glaciations, but the M3y and M4 are instead deposited during episodes of highly variable climate during marine isotope stages (MIS) 3 and 5. Incision notably occurs during interglacials or at least periods of low ice volume. In the Colorado Plateau, we suggest terrace sedimentation is linked to anemic peak flows during full glacial co