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1

Three-dimensional seismic fluvial architecture of the basal middle Frio Formation, Stratton and Agua Dulce fields, south Texas  

NASA Astrophysics Data System (ADS)

Facies architectural models are developed for the Oligocene basal middle Frio meandering fluvial system at Stratton and Agua Dulce fields in south Texas. These models are based on detailed mapping and are important to understand reservoir heterogeneities. The basal middle Frio is characterized in terms of a hierarchy of architectural elements at different heterogeneity levels. In order from small-scale to large-scale, these are facies, channel-belt, systems tract, and depositional sequence. A structural architecture model integrating well logs and 3-D seismic data is developed for the basal middle Frio. It indicates that growth faults are syndepositional and cut through the basal middle Frio Formation and younger sediments in the Stratton-Agua Dulce area. These affect the architecture of the sandstone bodies stacked in that interval. The dimensions, directions, and spatial locations of the basal middle Frio facies architectural elements are predicted from log facies maps and confirmed from seismic amplitude maps. RMS amplitude was related to rock properties and can be used to predict, among other things, facies type and net sand thickness. Seismic sequence stratigraphic models constructed for the basal middle Frio non-marine fluvial strata predict the location of new reservoirs that offer potential reserve growth in the Stratton-Agua Dulce field area. Observations from well logs and 3-D seismic data suggest that accommodation changes and nodal avulsions are possible factors controlling the basal middle Frio fluvial architecture. A 2-D facies architectural model is developed which describes the changes in the stacking patterns of the basal middle Frio sandstone deposits. Changes in the stacking patterns are a reflection of changes in accommodation space, avulsion frequency and sediment accumulation rate. The integrated 3-D fluvial facies architecture model of the basal middle Frio indicates that growth faults controlled the stacking patterns of the basal middle Frio sandstone reservoirs. Results of this study are significant in exploring for and developing similar meandering fluvial reservoirs affected by growth faulting in the Texas Gulf Coast and in similar geological settings worldwide.

El-Mowafy, Hamed Zeidan

2

Meandering: fluvial versus tidal. (Invited)  

Microsoft Academic Search

Tidal meanders (Marani et al, Water Resour Res, 2002) display similarities as well as important differences from fluvial meanders (Seminara, J Fluid Mech, 2006). Like fluvial meanders they have characteristic wavelengths scaling with channel width: this is why the convergent character of tidal channels leads to meander wavelengths decaying landward. Unlike fluvial meanders, the typical curvature spectra of tidal meanders

G. Seminara

2009-01-01

3

Simulations of Fluvial Landscapes  

NASA Astrophysics Data System (ADS)

The Smith-Bretherton-Birnir (SBB) model for fluvial landsurfaces consists of a pair of partial differential equations, one governing water flow and one governing the sediment flow. Numerical solutions of these equations have been shown to provide realistic models in the evolution of fluvial landscapes. Further analysis of these equations shows that they possess scaling laws (Hack's Law) that are known to exist in nature. However, the simulations are highly dependent on the numerical methods used; with implicit methods exhibiting the correct scaling laws, but the explicit methods fail to do so. These equations, and the resulting models, help to bridge the gap between the deterministic and the stochastic theories of landscape evolution. Slight modifications of the SBB equations make the results of the model more realistic. By modifying the sediment flow equation, the model obtains more pronounced meandering rivers. Typical landsurface with rivers.

Cattan, D.; Birnir, B.

2013-12-01

4

Quaternary fluvial archives: achievements of the Fluvial Archives Group  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

5

¡Agua Cambiante!  

NSDL National Science Digital Library

En esta actividad, los aprendices experimentarán con las tres fases del agua. Intentarán controlar la rapidez de los cambios de estado al manipular la temperatura y la presión del agua, hielo, y gas.

Science, Lawrence H.

2009-01-01

6

Fluvial valleys and Martian palaeoclimates  

NASA Technical Reports Server (NTRS)

Theoretical models of early Martian atmospheric evolution describe the maintenance of a dense CO2 atmosphere and a warm, wet climate until the end of the heavy-bombardment phase of impacting. However, the presence of very young, earthlike fluvial valleys on the northern flank of Alba Patera conflicts with this scenario. Whereas the widespread ancient Martian valleys generally have morphologies indicative of sapping erosion by the slow outflow of subsurface water, the local Alba valleys were probably formed by surface-runoff processes. Because subsurface water flow might be maintained by hydrothermal energy inputs and because surface-runoff valleys developed late in Martian history, it is not necessary to invoke drastically different planet-wide climatic conditions to explain valley development on Mars. The Alba fluvial valleys can be explained by hydrothermal activity or outflow-channel discharges that locally modified the atmosphere, including precipitation and local overland flow on low-permeability volcanic ash.

Gulick, Virginia C.; Baker, Victor R.

1989-01-01

7

Muestreo de aguas subterrneas a varias profundidades  

E-print Network

: bomba de muestreo Produce una mezclaProduce una mezcla de aguas dede aguas de diferentesdiferentes elponderadas por el caudal.caudal. #12;Muestreo a varias profundidades : bomba de muestreo divisoria de aguas: "Separation Pumping Technique", Nilsson et al., 1995 divisoria de aguas bomba superior

Politècnica de Catalunya, Universitat

8

Fluvial mudstone breccias and their petroleum significance  

SciTech Connect

The classic fining-upward model of fluvial deposition places mudstone breccia fragments as basal channel lag deposits. Basal breccias can form by bank erosion and collapse by migrating channels and channel down-cutting into preexisting mudstones. However, mudstone breccias associated with fluvial sediments display much wider distributions and can be found at the top of channel fills. Some formative mechanisms for breccias found toward the tops of fluvial sequences are (1) gravity sliding down point bar surfaces; (2) bank erosion and collapse by migrating underfit streams found within abandoned channel reaches undergoing vertical accretion and; (3) oversteepening and collapse of channel banks in response to stage fluctuations. Thus, breccia deposits can be located above or adjacent to well-sorted porous and permeable sands. In the subsurface, fluvial breccias are difficult to recognize in core if individual clasts are larger than the borehole diameter and flat lying. Dense concentrations of clasts also influence log readings by displaying high gamma-ray and relatively positive spontaneous potential responses. Core analyses commonly give misleadingly low indications of porosity and permeability because of the relatively small sample sizes available. It is very easy to mistake thick, dense concentrations of mudstone breccia for the deposits of shale-filled channels. Breccias found at the top of fluvial sequences are commonly overlooked reservoirs because hydrocarbons will be found in zones characterized by very large impervious blocks formed of muddy sediment. Recognition of the presence and distribution of breccias is crucial in the exploration and development of channel reservoirs.

Putnam, P.E.

1987-05-01

9

Quantifying the fluvial autogenic processes: Tank Experiments  

NASA Astrophysics Data System (ADS)

The evolution of deltaic shorelines has long been explained by allogenic changes in the environment such as changes in tectonics, base level, and sediment supply. Recently, the importance of autogenic cyclicity has been recognized in concert with allogenic forcing. Decoupling autogenic variability from allogenic signatures is essential in order to understand depositional systems and the stratigraphic record; however, autogenic behavior in sedimentary environments is not understood well enough to separate it from allogenic factors. Data drawn from model experiments that isolate the autogenic variability from allogenic forcing are the key to understanding and predicting autogenic responses in fluvial and deltaic systems. Here, three experiments using a constant water discharge (Qw) with a varying sediment flux (Qs) are conducted to examine the autogenic variability in a fluviodeltaic system. The experimental basin has dimensions of 1 m x 1 m, and a sediment/water mixture was delivered into the experimental basin. The sediment mixture contained 50% fine sand (.1 mm) and 50% coarse sand (2 mm) by volume and was delivered into the basin. The delta was built over a flat, non-erodible surface into a standing body of water with a constant base level and no subsidence. The autogenic responses of the fluvial and deltaic systems were captured by time-lapse images and the shoreline position was mapped to quantify the autogenic processes. The autogenic response to varying sediment supply while maintaining constant water supply include changes in 1) the slope of the fluvial-surface, 2) the frequency of autogenic storage and release events, and 3) shoreline roughness. Interestingly, the data shows a non-linear relationship between the frequency of autogenic cyclicity and the ratio of sediment supply to water discharge. The successive increase in the sediment supply and thus the increase in the ratio of Qs to Qw caused the slope of the fluvial surface to increase, and the frequency of autogenic sediment storage and release events to increase, but in a non-linear nature. This non-linear increase results from the autogenic frequency not increasing by a factor of 2 when the sediment flux increases by a factor of 2. Since the experimental data suggests that the frequency of autogenic variability is also related to the slope of the fluvial-surface, an increase in the fluvial slope would force the fluvial system to experience larger autogenic processes over a longer period of time. These three experiments are part of a larger matrix of nine total flume experiments, which explore variations in sediment supply, water discharge, and Qs/Qw to better understand fluvial autogenic processes.

Powell, E. J.; Kim, W.; Muto, T.

2010-12-01

10

Exploring hypsometry in glacial and fluvial environments  

NSDL National Science Digital Library

This laboratory exercise explores the topographic signature of fluvial and glacial landscapes in different tectonic environments. Students develop a list of mountain ranges around the world to explore, then extract topographic data from 90-meter SRTM DEMs, and develop a series of hypsometric curves for each range. Each student works on a single range, but as a class we build up a database of 10-15 ranges around the world. The hypsometric curves are compared with each other and with published curves to look for signals of fluvial incision vs. glacial erosion in the landscapes.

Gran, Karen

11

Large Fluvial Fans and Exploration for Hydrocarbons  

NASA Technical Reports Server (NTRS)

A report discusses the geological phenomena known, variously, as modern large (or large modern) fluvial fans or large continental fans, from a perspective of exploring for hydrocarbons. These fans are partial cones of river sediment that spread out to radii of 100 km or more. Heretofore, they have not been much recognized in the geological literature probably because they are difficult to see from the ground. They can, however, be seen in photographs taken by astronauts and on other remotely sensed imagery. Among the topics discussed in the report is the need for research to understand what seems to be an association among fluvial fans, alluvial fans, and hydrocarbon deposits. Included in the report is an abstract that summarizes the global distribution of large modern fluvial fans and a proposal to use that distribution as a guide to understanding paleo-fluvial reservoir systems where oil and gas have formed. Also included is an abstract that summarizes what a continuing mapping project has thus far revealed about the characteristics of large fans that have been found in a variety of geological environments.

Wilkinson, Murray Justin

2005-01-01

12

A fluvial mercury budget for Lake Ontario.  

PubMed

Watershed mercury (Hg) flux was calculated for ten inflowing rivers and the outlet for Lake Ontario using empirical measurements from two independent field-sampling programs. Total Hg (THg) flux for nine study watersheds that directly drain into the lake ranged from 0.2 kg/yr to 13 kg/yr, with the dominant fluvial THg load from the Niagara River at 154 kg/yr. THg loss at the outlet (St. Lawrence River) was 68 kg/yr and has declined approximately 40% over the past decade. Fluvial Hg inputs largely (62%) occur in the dissolved fraction and are similar to estimates of atmospheric Hg inputs. Fluvial mass balances suggest strong in-lake retention of particulate Hg inputs (99%), compared to dissolved total Hg (45%) and methyl Hg (22%) fractions. Wetland land cover is a good predictor of methyl Hg yield for Lake Ontario watersheds. Sediment deposition studies, coupled atmospheric and fluvial Hg fluxes, and a comparison of this work with previous measurements indicate that Lake Ontario is a net sink of Hg inputs and not at steady state likely because of recent decreases in point source inputs and atmospheric Hg deposition. PMID:24783951

Denkenberger, Joseph S; Driscoll, Charles T; Mason, Edward; Branfireun, Brian; Warnock, Ashley

2014-06-01

13

Fluvial sand shapes: effects of tributary mixing  

Microsoft Academic Search

Similarities and differences in gross shapes of fluvial quartz sand grains contain information useful for interpretation of sediment transport history. The shapes of sand grains in a given river depend on the source, or sources, of sand within the drainage basin and on the abrasion and shape sorting that has occurred during transport. It is highly unlikely that 2 major

1985-01-01

14

A Field Exercise in Fluvial Sediment Transport.  

ERIC Educational Resources Information Center

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

Tharp, Thomas M.

1983-01-01

15

Gestin del agua en producciones  

E-print Network

160 cm 220cm PER 240cm Gestión del agua en producciones de secano #12;#12;Sitio Prof. cm pH CE mmoh 31 oct s/napa soja Maíz Girasol Uso del agua - PER ­ sección control- relación con precipitaciones: Escenario lluvia alta -180,0 -160,0 -140,0 -120,0 -100,0 -80,0 -60,0 -40,0 -20,0 0,0 20/07/2012 19

Nacional de San Luis, Universidad

16

Folleto informativo de tecnologa de aguas residuales  

Microsoft Academic Search

La desinfeccin es considerada como el principal mecanismo para la desactivacin o destruccin de organismos patgenos con el fin de prevenir la dispersin de enfermedades transmitidas a travs del agua, tanto a los usuarios aguas abajo como al ambiente. Es muy importante que el agua residual sea tratada adecuadamente antes de realizarse las actividades de desinfeccin para que la accin

Organismo Enfermedad Causada

17

Martian fluvial conglomerates at Gale crater.  

PubMed

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. PMID:23723230

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 Moulic, 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

2013-05-31

18

Martian fluvial conglomerates at Gale Crater  

USGS Publications Warehouse

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.

Williams, Rebecca 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, Ryan B.; Herkenhoff, K.E.; Le Moulic, 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., III; Farmer, J.D.; Sullivan, R.; Van Beek, T.; Blaney, D.L.; Pariser, O.; Deen, R.G.

2013-01-01

19

Martian Fluvial Conglomerates at Gale Crater  

NASA Astrophysics Data System (ADS)

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.

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 Moulic, 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; Lveill, Richard; Marchand, Genevive; Sobrn Snchez, Pablo; Favot, Laurent; Cody, George; Steele, Andrew; Flckiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Isral, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Prez, Ren; Saccoccio, Muriel; Yana, Charles; Aparicio, Carlos Armiens; Caride Rodrguez, Javier; Carrasco Blzquez, Isaas; Gmez Gmez, Felipe; Elvira, Javier Gmez; Hettrich, Sebastian; Lepinette Malvitte, Alain; Marn Jimnez, Mercedes; Fras, Jess Martnez; Soler, Javier Martn; Torres, F. Javier Martn; Molina Jurado, Antonio; Sotomayor, Luis Mora; Muoz Caro, Guillermo; Navarro Lpez, Sara; Gonzlez, Vernica Peinado; Garca, Jorge Pla; Rodriguez Manfredi, Jos Antonio; Planell, Julio Jos Romeral; Alejandra Sans Fuentes, Sara; Sebastian Martinez, Eduardo; Torres Redondo, Josefina; O'Callaghan, Roser Urqui; Zorzano Mier, Mara-Paz; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairn, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Gnther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanp, Henrik; Kauhanen, Janne; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Fabre, Ccile; 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, Jrmie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schrder, Susanne; Toplis, Mike; Lewin, ric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Szopa, Cyril; Robert, Franois; Sautter, Violaine; Nachon, Marion; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; Franois, Pascaline; Raulin, Franois; Teinturier, Samuel; Cameron, James; Clegg, Sam; Cousin, Agns; 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

20

Riparian vegetation and fluvial geomorphic processes  

Microsoft Academic Search

Riparian vegetation and fluvial-geomorphic processes and landforms are intimately connected parts of the bottomland landscape. Relations among vegetation, processes, and landforms are described here for representative streams of four areas of the United States: high-gradient streams of the humid east, coastal-plain streams, Great Plains streams, and stream channels of the southwestern United States. Vegetation patterns suggest that species distributions in

Cliff R. Hupp; W. R. Osterkamp

1996-01-01

21

¡Truco Con Agua!  

NSDL National Science Digital Library

En esta actividad los aprendices aprenderán un truco de magia donde la magia es la presión del aire. Los participantes tomarán un vaso de agua medio lleno y lo taparán con un pedazo de plástico o cartón. Sosteniendo la tarjeta contra el vaso, lo voltearán boca abajo y cuando quiten la mano debajo del vaso, ¡abracadabra! no se caerá el agua. En la tira cómica, Mateo explica a los aprendices que la presión que hace el aire en todas las direcciones es la que sostiene la tarjeta.

Science, Lawrence H.

2009-01-01

22

Fluvial landscapes of the Harappan civilization.  

PubMed

The collapse of the Bronze Age Harappan, one of the earliest urban civilizations, remains an enigma. Urbanism flourished in the western region of the Indo-Gangetic Plain for approximately 600 y, but since approximately 3,900 y ago, the total settled area and settlement sizes declined, many sites were abandoned, and a significant shift in site numbers and density towards the east is recorded. We report morphologic and chronologic evidence indicating that fluvial landscapes in Harappan territory became remarkably stable during the late Holocene as aridification intensified in the region after approximately 5,000 BP. Upstream on the alluvial plain, the large Himalayan rivers in Punjab stopped incising, while downstream, sedimentation slowed on the distinctive mega-fluvial ridge, which the Indus built in Sindh. This fluvial quiescence suggests a gradual decrease in flood intensity that probably stimulated intensive agriculture initially and encouraged urbanization around 4,500 BP. However, further decline in monsoon precipitation led to conditions adverse to both inundation- and rain-based farming. Contrary to earlier assumptions that a large glacier-fed Himalayan river, identified by some with the mythical Sarasvati, watered the Harappan heartland on the interfluve between the Indus and Ganges basins, we show that only monsoonal-fed rivers were active there during the Holocene. As the monsoon weakened, monsoonal rivers gradually dried or became seasonal, affecting habitability along their courses. Hydroclimatic stress increased the vulnerability of agricultural production supporting Harappan urbanism, leading to settlement downsizing, diversification of crops, and a drastic increase in settlements in the moister monsoon regions of the upper Punjab, Haryana, and Uttar Pradesh. PMID:22645375

Giosan, Liviu; Clift, Peter D; Macklin, Mark G; Fuller, Dorian Q; Constantinescu, Stefan; Durcan, Julie A; Stevens, Thomas; Duller, Geoff A T; Tabrez, Ali R; Gangal, Kavita; Adhikari, Ronojoy; Alizai, Anwar; Filip, Florin; VanLaningham, Sam; Syvitski, James P M

2012-06-26

23

ESTUDIO DEL MECANISMO DE FALLA DE TERRAPLENES DEBIDO A LA INFILTRACIN DE AGUAS LLUVIAS MEDIANTE EL MONITOREO DE PRESIONES DE POROS Y CONTENIDOS DE AGUA STUDY OF FAILURE MECHANISM IN EMBANKMENTS INDUCED BY RAINFALL INFILTRATION BY MONITORING PORE WATER PRESSURES AND WATER CONTENTS  

Microsoft Academic Search

Recibido para revisar 27 de Julio de 2006, Aceptado 14 de Noviembre de 2006, Version final 24 de Enero de 2007 RESUMEN: El presente artculo muestra experimentos realizados utilizando modelos a escala para estudiar el proceso de infiltracin en terraplenes sometidos a aguas lluvias. Varios modelos a escala fueron construidos usando un suelo arenoso con alto contenido de finos; para

EDWIN GARCA; TARO UCHIMURA

2007-01-01

24

Fluvial processes on Mars: Erosion and sedimentation  

NASA Technical Reports Server (NTRS)

One of the most important discoveries of the Mariner 9 and Viking missions to Mars was evidence of change of the Martian surface by the action of liquid water. From the standpoint of a Mars Rover/Sample Return Mission, fluvial activity on Mars is important in two ways: (1) channel formation has deeply eroded the Martian crust, providing access to relatively undisturbed subsurface units; and (2) much of the material eroded from channels may have been deposited in standing bodies of liquid water. The most striking fluvial erosion features on Mars are the outflow channels. A second type of channel apparently caused by flow of liquid water is the valley systems. These are similar to terrestial drainage systems. The sedimentary deposits of outflow channels are often difficult to identfy. No obvious deposits such as deltaic accumulations are visible in Viking images. Another set of deposits that may be water lain and that date approx. from the epoch of outflow channels are the layered deposits in the Valles Marineris. From the standpoint of a Mars Rover/Sample Return mission, the problem with all of these water-lain sediments is their age, or rather the lack of it.

Squyres, Steven W.

1988-01-01

25

AGUA TIBIA PRIMITIVE AREA, CALIFORNIA.  

USGS Publications Warehouse

The Agua Tibia Primitive Area in southwestern California is underlain by igneous and metamorphic rocks that are siilar to those widely exposed throughout much of the Peninsular Ranges. To detect the presence of any concealed mineral deposits, samples of stream sediments were collected along the various creeks that head in the mountain. As an additional aid in evaluating the mineral potential, an aeromagnetic survey was made and interpreted. A search for records of past or existing mining claims within the primitive area was made but none was found. Evidence of deposits of metallic or nonmetallic minerals was not seen during the study.

Irwin, William P.; Thurber, Horace K.

1984-01-01

26

Fluvial erosion on Mars: Implications for paleoclimatic change  

NASA Technical Reports Server (NTRS)

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.

Gulick, Virginia C.; Baker, Victor R.

1993-01-01

27

Erosion of biofilm-bound fluvial sediments  

NASA Astrophysics Data System (ADS)

The movement of fluvial sediment shapes our rivers. Understanding sediment entrainment has been a goal of hydraulic engineers for almost a century. Previous sediment entrainment models have been informed by laboratory experiments using grains that were free from biological material. In natural river settings, however, sediments are invariably covered by bacteria, often forming visible biofilms, which comprise diverse consortia of species housed in sticky extracellular polysaccharides. Here we report experiments in a laboratory flume with cyanobacteria grown over sediment. We show that the prevailing model, where grains roll over one another at some critical threshold in shear velocity, does not hold for biofilm-bound sediments. Instead, biostabilized sediment behaves more like an elastic membrane. Fluid flow produces oscillations in the membrane, which can become unstable. Beyond a particular threshold in velocity, the membrane fails catastrophically by ripping and clumps of biofilm-bound sediment become entrained. We use a mathematical model of an oscillating membrane in incompressible flow to show that unstable oscillations will occur over a wide range of elastic material properties at realistic river flow velocities. We find that the horizontal length scale over which oscillations occur is a controlling factor for incipient sediment entrainment of biostabilized sediments.

Vignaga, Elisa; Sloan, David M.; Luo, Xiaoyu; Haynes, Heather; Phoenix, Vernon R.; Sloan, William T.

2013-09-01

28

Seismic modeling of fluvial reservoirs in outcrop  

SciTech Connect

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.

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

1993-09-01

29

Distributive Fluvial Systems of the Chaco Plain - Satellite Image Assessment of Fluvial Form and Facies Distributions  

NASA Astrophysics Data System (ADS)

Distributive fluvial systems (DFS) dominate fluvial deposition inside modern continental sedimentary basins and are particularly extensive in modern foreland basins. The largest of these DFS are found in the Chaco Plain, Andean Foreland Basin, South America. We use published literature, field and satellite data (Landsat, Modis, and SRTM) to construct preliminary hypotheses about the geomorphic form and fluvial facies distributions on the DFSs in this basin. The Pilcomayo River DFS extends over 700 km from apex to toe. The river enters the DFS apex as a large braided river with a bankfull channel width of 2500 m. Gravels and cobbles occur in terraces cut through the apex. At ~70-km downstream the bankfull channel width is ~2000 m and the channel is dominated by fine sand with cut banks 2-3 m high. The proximal channel belt is surrounded by floodplain sediments, however many sandy abandoned channel belts are present across the DFS, indicating a mobile channel system. Abandoned channels have a similar form to the modern channel, with minor reworking by underfit meandering streams. At ~75-km downfan, the river system diminishes in size (bankfull channel width up to 2 km but generally <1.5 km) and becomes increasingly sinuous in planform. This point appears to serve as a node for a series of recently abandoned meander belts and splays associated with discrete channels surrounded by floodplain material. At 100 km downstream the planform is highly sinuous and bankfull width has decreased to 1500 m or less. Downstream of this area abandoned meander belts dominate along the flanks of the modern channel with oxbow lakes present adjacent to the active channel. At 150 km downstream the bankfull channel belt width is 500 m or less and the river bifurcates into splays and multiple active channels which extend downstream for a further 200 km. Vegetation maps derived from Modis imagery indicate an increase in tree density around the DFS at this elevation (230 m). Along the distal portion of the DFS, a springline at ~150 m elevation separates the upper, well drained, aridisol dominated dry Chaco area of the DFS from the poorly drained wet Chaco at the toe. Channels below this line remain wet, are mud-dominated, and associated soils are hydromorphic. At the termination of the DFS the main Pilcomayo channel has a bankfull width of 120 m with sediments consisting of interbedded fine sand and mudstone. The observations from the Pilcomayo can serve as important analogues for the development of DFS in ancient foreland basin successions, particularly the recognition of the radial distribution of distinct facies types and the downstream changes in soil types associated with the spring line.

Weissmann, G. S.; Hartley, A. J.; Scuderi, L.; Bhattacharyya, P.; Buehler, H.; Leleu, S.; Mather, A.

2009-12-01

30

54. Downstream face of Agua Fria project's diversion dam showing ...  

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

54. Downstream face of Agua Fria project's diversion dam showing initial masonry construction and poured concrete capping. Photographer Mark Durben, 1986. Source: Salt River Project. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

31

Fluvial network organization imprints on microbial co-occurrence networks.  

PubMed

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

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

2014-09-01

32

Fluvial-deltaic sedimentation and stratigraphy of the ferron sandstone  

USGS Publications Warehouse

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.

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

1997-01-01

33

Fluvial landforms on fresh impact ejecta on Mars  

NASA Astrophysics Data System (ADS)

Fluvial valleys provide critical clues to the distribution and state of water throughout the history of the planet Mars. Early in Mars' history (<3.7 Gy), the climate may have been warmer than at present leading to the development of valley networks. Younger valleys formed on volcanic and glacial landforms under colder conditions than experienced in Mars' early history. Only rare examples of fluvial valleys over fresh impact craters have been reported. In the present study, a survey of hundreds of fresh post-Noachian impact craters (of 12 to 150 km in diameter) has been done to identify fluvial landforms, especially in regions lacking ancient valleys, using images from the High Resolution Stereo Camera (HRSC) instrument onboard Mars Express and from the Context Camera (CTX) instrument onboard Mars Reconnaissance Orbiter. Observations show that these valleys are locally sinuous, display isolated channels, a poor connectivity and frequent braiding. Valleys were most likely formed over a short duration with high discharge rates, estimated from 500 to 40,000 m3 s-1. In Arabia Terra, a total of 27 out of the 204 surveyed craters were found to have fluvial landforms on the ejecta blanket, exclusively in the mid-latitude band (25-45). Dating of impact ejecta gives young ages from the Late Hesperian to the Middle Amazonian, thus providing a temporal constraint for the fluvial activity. Late climatic episodes of snow deposition and subsequent melting scattered in space and time could explain observations. Alternatively, the thermal anomaly of impacts and their ejecta over ice-bearing terrains is a possible triggering mechanism for the observed fluvial valleys. Calculations show that the thermal anomaly can persist in the ejecta over several hundreds of years for mid-size craters (20-40 km). Such a process would not explain all Martian fluvial activity because of the marked difference between the pristine landforms described and Late Noachian valley networks. Nevertheless, fluvial landforms on preserved ejecta blankets can be used as a new proxy for the temporal distribution of water on Mars.

Mangold, N.

2012-03-01

34

CIENCIA, TECNOLOGA, POLTICA Y PLANIFICACIN DEL AGUA Y DE  

E-print Network

de lluvia, reutilización... Adicionalmente al uso del agua y a pesar de que tenemos cada vez unassegunda circular enero 2011 CIENCIA, TECNOLOGÍA, POLÍTICA Y PLANIFICACI?N DEL AGUA Y DE LA ENERGÍA EN LOS REGADÍOS. ASPECTOS SOCIOEC?NOMICOS Y AMBIENTALES. AGRICULTURA, AGUA Y ENERGÍA colaboran MADRID

Escolano, Francisco

35

CONSERVE SU SALUD DURANTE UN DESASTRE Alimentos y agua  

E-print Network

CONSERVE SU SALUD DURANTE UN DESASTRE Alimentos y agua Las situaciones de emergencia pueden afectar para tres días de 1 galon de agua por persona y por día para beber, higiene y cocinar. Mantengase hidratado bebiendo ocho vasos de 8 onzas de agua por día. #12;Los programas educativos de Texas A&M Agri

36

Geometry and Distribution of Fluvial Landforms on Mars from HRSC-Mars Express Stereo Imagery  

NASA Astrophysics Data System (ADS)

3D geometry and distribution of fluvial landforms on Mars, viewed from HRSC-Mars Express stereo imagery, help us to understand the past fluvial activity on Mars surface, and assess implications for climatic conditions during early Mars.

Ansan, V.; Mangold, N.

2014-07-01

37

Problemtica de las aguas cidas en la FPI y monitorizacin del flujo de agua y calor a  

E-print Network

Problemática de las aguas ácidas en la FPI y monitorización del flujo de agua y calor a través de con el oxígeno y el agua. · Los residuos de la actividad minera aceleran los procesos de oxidación de sulfuros #12;· Cuando no se dispone de suficientes minerales alcalinos en el medio el agua superficial

Politècnica de Catalunya, Universitat

38

Titan's fluvial valleys: Morphology, distribution, and spectral properties  

USGS Publications Warehouse

Titan's fluvial channels have been investigated based on data obtained by the Synthetic Aperture Radar (SAR) instrument and the Visible and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. In this paper, a database of fluvial features is created based on radar-SAR data aiming to unveil the distribution and the morphologic and spectral characteristics of valleys on Titan on a global scale. It will also study the spatial relations between fluvial valleys and Titan's geologic units and spectral surface units which have become accessible thanks to Cassini-VIMS data. Several distinct morphologic types of fluvial valleys can be discerned by SAR-images. Dendritic valley networks appear to have much in common with terrestrial dendritic systems owing to a hierarchical and tree-shaped arrangement of the tributaries which is indicative of an origin from precipitation. Dry valleys constitute another class of valleys resembling terrestrial wadis, an indication of episodic and strong flow events. Other valley types, such as putative canyons, cannot be correlated with rainfall based on their morphology alone, since it cannot be ruled out that they may have originated from volcanic/tectonic action or groundwater sapping. Highly developed and complex fluvial networks with channel lengths of up to 1200 km and widths of up to 10 km are concentrated only at a few locations whereas single valleys are scattered over all latitudes. Fluvial valleys are frequently found in mountainous areas. Some terrains, such as equatorial dune fields and undifferentiated plains at mid-latitudes, are almost entirely free of valleys. Spectrally, fluvial terrains are often characterized by a high reflectance in each of Titan's atmospheric windows, as most of them are located on Titan's bright 'continents'. Nevertheless, valleys are spatially associated with a surface unit appearing blue due to its higher reflection at 1.3??m in a VIMS false color RGB composite with R: 1.59/1.27??m, G: 2.03/1.27??m, and B: 1.27/1.08??m; the channels either dissect pure bluish surface units or they are carved into terrain with a mixed spectral signature between bright and bluish surface materials. The global picture of fluvial flows clearly indicates a high diversity of parameters controlling fluvial erosion, such as climatic processes, as well as surface and bedrock types. Recent fluvial activity is very likely in the north polar region in contrast to more arid conditions at lower latitudes and at the south pole of Titan. This divergence is probably an indication of seasonal climatic asymmetries between the hemispheres. However, traces of previous fluvial activity are scattered over all latitudes of Titan, which is indicative of previous climatic conditions with at least episodic rainfall. ?? 2011 Elsevier Ltd. All rights reserved.

Langhans, M.H.; Jaumann, R.; Stephan, K.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Baines, K.H.; Nicholson, P.D.; Lorenz, R.D.; Soderblom, L.A.; Soderblom, J.M.; Sotin, C.; Barnes, J.W.; Nelson, R.

2012-01-01

39

Detection of rapid climate change in Last Glacial fluvial successions in The Netherlands  

Microsoft Academic Search

Climate change during the Last Glacial is considered as a major forcing factor of fluvial system changes. A continuous succession of fluvial sediments, reflecting adaptations to climate change from the Weichselian Middle Pleniglacial (oxygen isotope stage 3) onwards, occurs in lowland river basins in the Netherlands.A comparison of the Pleniglacial and Late Glacial fluvial record in the Netherlands shows that

J van Huissteden; C. Kasse

2001-01-01

40

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

41

2. William Beardsley standing along the Agua Fria River near ...  

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

2. William Beardsley standing along the Agua Fria River near construction site of the Agua Fria project. Photographer James Dix Schuyler, 1903. Source: Schuyler, James D. 'Report on the Water Supply of the Agua Fria River, and the Storage Reservoir Project of the Agua Fria Water and Land Company For Irrigation in the Gila River Valley, Arizona,' (September 29, 1903). Arizona Historical Collection, Hayden Library, Arizona State University, Tempe, Arizona. (Typewritten.) - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

42

Architectural studies of Jurassic-Cretaceous fluvial units, Colorado Plateau  

SciTech Connect

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.

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

1989-03-01

43

Modeling fluvial erosion on regional to continental scales  

Microsoft Academic Search

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

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

1994-01-01

44

Linking fluvial bed sediment transport across scales Yong Zhang,1  

E-print Network

, L20404, doi:10.1029/2012GL053476. 1. Introduction [2] Bed sediment transport in rivers is scaleLinking fluvial bed sediment transport across scales Yong Zhang,1 Mark M. Meerschaert,2 and Aaron I often seen in rivers. Particles alternate between mobile and resting phases, with a tempered stable

Meerschaert, Mark M.

45

Impact of glacial erosion on 10 Be concentrations in fluvial  

E-print Network

Impact of glacial erosion on 10 Be concentrations in fluvial sediments of the Marsyandi catchment] Several processes contribute to denudation in high-mountain environments. Of these, glacial erosion significant variations in glacial erosion, both in space and magnitude, within the Marsyandi catchment

Bookhagen, Bodo

46

Fluvial geomorphic features of the Lower Mississippi alluvial valley  

Microsoft Academic Search

The Lower Mississippi Valley (LMV) has been one of the most intensively studied alluvial valleys in the world in terms of it's geological and geomorphic framework and history. A brief outline of the history of the major geological and geomorphological investigations of the LMV is provided. The results of these investigations are discussed in terms of the fluvial geomorphic framework

Lawson M. Smith

1996-01-01

47

Vision for a worldwide fluvial-sediment information network  

USGS Publications Warehouse

The nations of the world suffer both from the deleterious effects of some natural and human-altered fluxes of fluvial sediment and a lack of consistent and reliable information on the temporal and spatial occurrence of fluvial sediments. Decades ago, this difficulty was unavoidable due to a lack of understanding of the magnitude and scope of environmental influences exerted by fluvial sediment coupled with a dearth of tools for monitoring and studying the data. Such is no longer the case. Fluvial sediment has a broad influence on the environment and humanity. Data needs that were once limited primarily to reservoir and channel maintenance now include issues associated with public water supply; contaminated sediment management; productivity of agricultural lands; stream restoration and watershed health; in-stream biotic stability; post-wildfire channel morphology; dam decommissioning, rehabilitation, or removal; and legal requirements for sediment management (Gray and Glysson, 2005). The adverse effects of poorly managed or unmanaged sediment movement related to these and other issues are well-known qualitatively, and in some cases quantitatively. For example, physical, chemical, and biological damages attributable to fluvial sediment in North America alone are now estimated to range between $20 billion and $50 billion annually (Pimental and others, 1995; Osterkamp and others, 1998; 2004). Capabilities for monitoring, analyzing, storing, and sharing fluvial-sediment data have been developed and, in many cases, are sufficiently mature for consideration for global utilization. Hence, there is not only a strong and expanding need for a global effort to gauge and understand fluvial-sediment characteristics and processes better, but the knowledge and tools to achieve these ends are largely available and ready for their applicability to be evaluated. Given the increasing importance of erosion and sediment processes for water-resources management, an International Sedimentation Initiative (ISI, 2007a), under the United Nations Educational, Scientific, and Cultural Organizations International Hydrologic Programme (IHP, 2007) was adopted in 2004. The ISI, the focus of which is on sustainable water-resources management on the global scale, features six major activities and projects, which are listed as part of the section entitled, Relation of the WoFSIN concept to the thrusts of the International Sedimentation Initiative, that precedes the Conclusions section of this paper. Based on the need for more, and more consistent and reliable fluvial-sediment information and on the existence of the ISI and other international and national sediment programs, we envision the need for a Worldwide Fluvial Sediment-Information Network (WoFSIN) with a focus on data acquisition, storage, and dissemination globally. Envisioned components of a WoFSIN, administered largely via the Internet and relying mostly on the benefits derived from existing resources and programs, follow that summary. The goal of the WoFSIN is to maximize the availability and usefulness of the worlds historical and current fluvial-sediment and ancillary data through collaboration with existing programs so as to require few additional resources in the long-term. Thus, the WoFSIN concept was developed recognizing that informed resource management is predicated on the availability of adequate and reliable information. The WoFSIN is described in the ensuing sections in stand-alone fashion, followed by a section that describes the complementary aspects of the WoFSIN and the International Sediment Initiative. Thus, our first objective is to describe the fundamental components of a WoFSIN. Our second objective is to identify overlap or gaps between the WoFSIN and ISI concepts that might be useful in refining the ISIs ability to meet its global mission to develop decision support for sediment management at the global scale more fully, cost-effectively, and (or) with enhanced quality.

Gray, J.R.; Osterkamp, W.R.

2007-01-01

48

Fluvial channels on Titan: Initial Cassini RADAR observations  

Microsoft Academic Search

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

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

49

A Search for Unconfined Fluvial Outflow Deposits on Mars  

NASA Technical Reports Server (NTRS)

Fluvial processes have been active during a large portion of Martian history, as evidenced by a variety of erosional features, ranging from concentrations of small channels to scour features generated by floods that affected enormous areas on Mars. Most research efforts prior to Mars Global Surveyor (MGS) focused on channelized reaches since these were some of the most convincing fluvial features on the planet. Since MGS reached its planned mapping orbit in 1999, a new era of Mars exploration has been opened. The m-scale resolution of the Mars Orbiter Camera (MOC), the precise elevation measurements of the Mars Orbiter Laser Altimeter (MOLA), and the compositional constraints derived from the Thermal Emission Spectrometer (TES) allows one now to search for deposits as well as erosional landforms. Here we describe our initial efforts at a search for deposits on Mars where flow was no longer confined within a topographic channel. We are using both new MGS and existing Viking data, in conjunction with field results of fluvial deposits in unconfined reaches from central Australia and elsewhere as analogues for the deposit characteristics to search for on Mars. Additional information is contained in the original extended abstract.

Zimbelman, J. R.; Bourke, M. C.

2000-01-01

50

Does deposition depth control the OSL bleaching of fluvial sediment?  

NASA Astrophysics Data System (ADS)

The Optically Stimulated Luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could potentially provide insights into geomorphic processes. However, comparison of bleaching between samples is complicated by sample-to-sample variation in aliquot size and luminescence sensitivity. Here we develop an age model to account for these effects. With measurement data from multi-grain aliquots, we use Bayesian computational statistics to estimate the burial dose and bleaching parameters of the single-grain dose distribution. We apply the model to 46 samples taken from fluvial sediment of Rhine branches in the Netherlands, and compare the results with environmental predictor variables (depositional energy and environment, sample depth, depth relative to mean water level, dose rate). We find no significant correlations between any predictor variable and the bleaching parameters, although large uncertainties may be obscuring relationships. However, the best bleached samples are found close to the mean water level. Based on these results, we hypothesize that bleaching occurs mainly during fluvial transport rather than upon deposition, with extra bleaching possible for sediments near the transition of channel to overbank deposits due to local reworking after deposition either by wind or water.

Cunningham, A. C.; Wallinga, J.; Hobo, N.; Versendaal, A. J.; Makaske, B.; Middelkoop, H.

2014-07-01

51

I CONGRESO INTERNACIONAL DEL AGUA .... por la vida  

E-print Network

Guayana, Estado Bolívar, Venezuela. Mesa # 7: Reducir los riesgos y hacer frente a la incertidumbre la naturaleza transversal y compleja del riesgo y el agua. 2. Riesgo y agua en Venezuela, un monitoreo poco consolidado para una exposición territorial a la amenaza alta. (3) Venezuela tiene

Paris-Sud XI, Université de

52

Energy, time, and channel evolution in catastrophically disturbed fluvial systems  

USGS Publications Warehouse

Two diverse fluvial systems show that with time, channels adjust such that the rate of energy dissipation is minimized. One fluvial system, characterized by high relief and coarse-grained sediment, was subjected to an explosive volcanic eruption; the other system, characterized by low relief and fine-grained sediment, was subjected to dredging and straightening. Study of the expenditure of kinetic- and potential-energy components of total-mechanical energy provide an energy-based rationale of the interdependency between processes and forms during channel evolution. Spatial and temporal trends of aggradation and degradation are similar although relative amounts of aggradation in the high-energy system are greatly enhanced by the deposition of large amounts of eroded bank material from upstream reaches. Degradation accompanied by widening is the most efficient means of energy dissipation because all components of total-mechanical energy decrease with time. Widening dominates energy dissipation in the coarse-grained system to offset increases in hydraulic depth caused by incision. In the low-energy fine-grained system, channel adjustment and energy dissipation are dominated by vertical processes because of low relative values of kinetic energy, and because eroded bank sediment is transported out of the drainage basin and does not aid in downstream aggradation, energy dissipation, or channel recovery. Specific energy is shown to decrease nonlinearly with time during channel evolution and provides a measure of reductions in available energy at the channel bed. Data from two sites show convergence towards a minimum specific energy with time. Time-dependent reductions in specific energy at a point act in concert with minimization of the rate of energy dissipation over a reach during channel evolution as the fluvial systems adjust to a new equilibrium. ?? 1992.

Simon, A.

1992-01-01

53

Progress in coupling models of coastline and fluvial dynamics  

NASA Astrophysics Data System (ADS)

The morphology and depositional history of wave-influenced deltas reflects the interplay between the fluvial and coastal domains. Here we present initial results of the coupling of stand-alone coastal and terrestrial models within the Community Surface Dynamics Modeling System (CSDMS) Component Modeling Tool (CMT), applied to study the evolution of wave-influenced deltas. The coastal domain is modeled using the Coastline Evolution Model (CEM), which simulates plan-view shoreline evolution due to wave-driven alongshore sediment transport, with fluvial influence incorporated by adding sediment along the coastline. The first application involves one-way coupling of the climate-driven hydrological transport model HydroTrend with CEM to investigate how fluctuations in sediment input rates due to climate change may affect the plan-view delta morphology and evolution. Simulations reveal that sediment discharge variability can have a significant effect on delta morphology if fluvial delivery of sediment temporarily exceeds the capacity for alongshore sediment transport to remove sediment from regions proximal to the river mouth. The second application involves two-way coupling of CEM with a river with multiple active distributary channels. In this case, changes to the coastline affect the apportionment of discharge flowing out of coeval distributaries through a two-way feedback. Model simulations where distributary length affects sediment discharge demonstrate how the dynamics of one distributary can control the sediment discharge of another. Wave-influenced deltas exhibiting strong channel feedbacks may prograde delta lobes faster than those without feedback. These preliminary model experiments demonstrate the capability of CMT to bidirectionally couple models that represent different process domains and were developed and designed independently (i.e. without the intentions of such coupling), offering the potential for further numerical studies of interactions taking place at the intersection of different process realms.

Ashton, Andrew D.; Hutton, Eric W. H.; Kettner, Albert J.; Xing, Fei; Kallumadikal, Jisamma; Nienhuis, Jaap; Giosan, Liviu

2013-04-01

54

New Mesoscale Fluvial Landscapes - Seismic Geomorphology and Exploration  

NASA Technical Reports Server (NTRS)

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.

Wilkinson, M. J.

2013-01-01

55

Wilmington Submarine Canyon: a marine fluvial-like system.  

USGS Publications Warehouse

Midrange sidescan sonar data show that a system of gullies and small channels feeds into large submarine canyons on the Middle Atlantic Continental Slope of the US. The surveyed canyons all have relatively flat floors, but they have different channel morphologies. Wilmington Canyon has a meandering channel that extends down the Continental Slope and across the Continental Rise, whereas two canyons south of Wilmington Canyon have straight channels that trend directly downslope onto the rise. The morphology of these submarine canyon systems is remarkably similar to that of terrestrial fluvial systems.-Authors

McGregor, B.; Stubblefield, W.L.; Ryan, William B. F.; Twichell, D.C.

1982-01-01

56

Quantifying the transition from fluvial- to wave-dominance for river deltas with multiple active channels  

NASA Astrophysics Data System (ADS)

The plan-view morphologies of fluvial- and wave-dominated deltas are clearly distinctive, but transitional forms are numerous. A quantitative, process-based description of this transition remains unexplored, particularly for river deltas with multiple active channels. Previous studies focused on general attributes of the fluvial and marine environment, such as the balance between wave energy and river discharge. Here, we propose that the transition between fluvial and wave dominance is directly related to the magnitude of the fluvial bedload flux to the nearshore region versus the alongshore sediment transport capacity of waves removing sediment away from the mouth. In the case of a single-channel delta, this balance can be computed for a given distribution of waves approaching shore. Fluvial dominance occurs when fluvial sediment input exceeds the wave-sustained maximum alongshore sediment transport for all potential shoreline orientations both up- and downdrift of the river mouth. However, deltaic channels have the tendency to bifurcate with increasing fluvial strength. Initial bifurcation splits the fluvial sediment flux among individual channels, while the potential sediment transport by waves remains constant for both river mouths. At higher bifurcation orders, multiple channels interact with each other alongshore, a situation more complicated than the single channel case and one that cannot be simple addressed analytically. We apply a model of plan-view shoreline evolution to simulate the evolution of a deltaic environment with multiple active channels. A highly simplified fluvial domain is represented by deposition of sediment where channels meet the coast. We investigate two scenarios of fluvial delivery. The first scenario deposits fluvial sediment alongshore on a self-similar predefined network of channels. We analyze the effects of different network geometrical parameters, such as bifurcation length, bifurcation angle, and sediment partitioning. In the second scenario, local conditions help determine where channels form, distribute sediment and bifurcate, therefore allowing feedbacks between the marine and fluvial domains. With increasing fluvial sediment flux, the delta transitions from a classic cuspate morphology to a space-filling, radial fluvial delta. This simplified model allows us to quantify the transition from fluvial to wave dominance and enables comparisons with natural examples near this transition, such as the Tinajones lobe of the Sinu River Delta, Colombia, and the Po Delta, Italy.

Nienhuis, J.; Ashton, A. D.; Giosan, L.

2012-12-01

57

Optimality approaches to describe characteristic fluvial patterns on landscapes.  

PubMed

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

Paik, Kyungrock; Kumar, Praveen

2010-05-12

58

Fluvial channels on Titan: Initial Cassini RADAR observations  

USGS Publications Warehouse

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 polar lakes, suggesting slower-moving flow depositing fine-grained sediments. A third type, seen predominantly at mid- and high latitudes, have radar brightness patterns indicating topographic incision, with valley widths of up to 3 km across and depth of several hundred meters. These observations show that fluvial activity occurs at least occasionally at all latitudes, not only at the Huygens landing site, and can produce channels much larger in scale than those observed there. The areas in which channels are prominent so far amount to about 1% of Titan's surface, of which only a fraction is actually occupied by channels. The corresponding global sediment volume inferred is not enough to account for the extensive sand seas. Channels observed so far have a consistent large-scale flow pattern, tending to flow polewards and eastwards. ?? 2008.

Lorenz, R.D.; Lopes, R.M.; Paganelli, F.; Lunine, J.I.; Kirk, R.L.; Mitchell, K.L.; Soderblom, L.A.; Stofan, E.R.; Ori, G.; Myers, M.; Miyamoto, H.; Radebaugh, J.; Stiles, B.; Wall, S.D.; Wood, C.A.

2008-01-01

59

Fluvial sediment fingerprinting: literature review and annotated bibliography  

USGS Publications Warehouse

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.

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

2014-01-01

60

Fluvial ecosystem resilience and stability: the role of riparian vegetation  

NASA Astrophysics Data System (ADS)

Riparian vegetation impacts fluvial landform resistance and resilience. Here we analyse the spatial and temporal pattern of biogeomorphic equilibrium conditions within a high energy river system. We quantified rejuvenation and maturation of the biogeomorphic succession using a spatial explicit analysis based on aerial photographs at six dates between 1942 and 2000. The Mediterranean River Tech, France, was chosen because a catastrophic flood in 1940 (recurrence time > 100 years) nearly completely destroyed the riparian forest and thus rejuvenated the biogeomorphic succession, providing a reference state in 1942. Interactions between vegetation establishment and flood regime enhanced the replacement of the dense riparian forest removed in 1940 at the scale of the corridor. Following this major disturbance, the riparian landscape demonstrated a very high resilience related to a positive biogeomorphic feedback driven by pioneer riparian engineer plants trapping sediments. This positive feedback enhanced floodplain construction, vegetation succession and a non-linear increase in biogeomorphic stability. Biogeomorphic equilibrium (ratio between instable active tract and stabilised riparian margins) driven by the interplay of vegetation dynamics and hydrogeormorphic processes was reached thirty years after the catastrophic flood event. The results suggest the existence of abrupt transitions between alternative domains of stability and hysteresis cycles. Based on these findings we propose a topological model of riparian ecosystem resistance and resilience according to biogeomorphic feedbacks. Furthermore, the proposed model developed on the River Tech suggests that biogeomorphic feedbacks play a critical role for transitions between different fluvial styles which determine the evolutionary trajectories of rivers.

Corenblit, Dov; Steiger, Johannes

2014-05-01

61

Fluvial deposits as an archive of early human activity  

NASA Astrophysics Data System (ADS)

River terraces are well established as an important source of Lower and Middle Palaeolithic artefacts in Europe, large collections having been assembled there during the years of manual gravel extraction. Now that many terrace sequences can be reliably dated and correlated with the oceanic record, potentially useful patterns can be recognized in the distribution of artefacts. The earliest appearance of artefacts in terrace staircases, marking the arrival of the first tool-making hominins in the region in question, is the first of several archaeological markers within fluvial sequences. The Lower to Middle Palaeolithic transition, with the appearance of Levallois, is another. Others may be more regional in significance: the occurrences of Clactonian (Mode 1) industry, twisted ovate handaxes and bout coup handaxes, for example. IGCP Project no. 449 instigated the compilation of fluvial records from all over the 'old world'. Comparison between British and Central European sequences confirms the established view that there is a demarcation between handaxe making in the west and flake/core industries in the east. Other centres of activity reported here have been in the Middle East (Syria), South Africa and India. Data from such areas will be key in deciphering the story of the earlier 'out-of-Africa' migration, that by pre-Homo sapiens people. There is clear evidence for diachroneity between the first appearances of different industries, in keeping with the well-established idea of northward migration.

Mishra, S.; White, M. J.; Beaumont, P.; Antoine, P.; Bridgland, D. R.; Limondin-Lozouet, N.; Santisteban, J. I.; Schreve, D. C.; Shaw, A. D.; Wenban-Smith, F. F.; Westaway, R. W. C.; White, T. S.

2007-11-01

62

Optimality approaches to describe characteristic fluvial patterns on landscapes  

PubMed Central

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

Paik, Kyungrock; Kumar, Praveen

2010-01-01

63

Revegetation of Fluvial Mine Tailing Deposits: The Use of Five Riparian Shrub Species  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fluvial deposition of mine tailings has caused extensive damage to riparian ecosystems throughout the West. Willows are often used for revegetation of fluvial mine tailing deposits but some species accumulate toxic concentrations of metals in leaves and stems. A greenhouse experiment was conducted ...

64

Fluvial history of the northern Upper Rhine River (southwestern Germany) during the Lateglacial and Holocene times  

Microsoft Academic Search

Three time slices were focused on reconstruction of the Lateglacial and Holocene landscape evolution in the northern Upper RhineRift Valley. The fluvial history of the northern Upper Rhine River during the last 15,000 years is characterised by repeated rapid changes of fluvial morphodynamics and sedimentation conditions. In consequence, the floodplain of the Rhine River may be subdivided into three different

Rainer Dambeck; Heinrich Thiemeyer

2002-01-01

65

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

Microsoft Academic Search

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

Calvin M. Kaya; Eric D. Jeanes

1995-01-01

66

12.5 Riparian Vegetation and the Fluvial Environment: A Biogeographic Perspective  

E-print Network

12.5 Riparian Vegetation and the Fluvial Environment: A Biogeographic Perspective J Bendix 12.5.2 Early History: Pattern and Process in Riparian Zones 54 12.5.3 Influence of Hydrogeomorphology the historical arc of research on biogeomorphic interactions between fluvial geomorphology and riparian

Stella, John C.

67

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

Microsoft Academic Search

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

Jeffrey J Whicker; Jason P Field; David D Breshears

2008-01-01

68

Simulating the development of martian highland landscapes through the interaction of impact cratering, fluvial erosion,  

E-print Network

the early martian landscape is explored here using a simulation model that incorporates formation of impact, drainage networks are short, and fluvial bajadas infill crater basins with sediment supplied from erosion burial by sediment infilling. Fluvial erosion on early Mars was sufficient to infill craters of 10 km

Howard, Alan D.

69

Human-induced changes in animal populations and distributions, and the subsequent effects on fluvial systems  

Microsoft Academic Search

Humans have profoundly altered hydrological pathways and fluvial systems through their near-extirpation of native populations of animal species that strongly influenced hydrology and removal of surface sediment, and through the introduction of now-feral populations of animals that bring to bear a suite of different geomorphic effects on the fluvial system. In the category of effects of extirpation, examples are offered

David R. Butler

2006-01-01

70

En el ao 1991se creaba el Insti-tuto Universitario del Agua y las  

E-print Network

en el tratamiento de aguas residuales industriales, experien- cias de reutilización de aguas resiEn el año 1991se creaba el Insti- tuto Universitario del Agua y las Ciencias otra denominación, se imparte el máster Gestión Sostenible y Tec- nología del Agua, adaptado al Es

Escolano, Francisco

71

Lahar hazards at Agua volcano, Guatemala  

USGS Publications Warehouse

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 debrisalso known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

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

2001-01-01

72

Last Glacial and Holocene fluvial wetland sedimentary stratigraphy: Comparison between Soro-ri and Jangheung-ri archeological sites, Korea  

Microsoft Academic Search

Environmental changes in wetlands during the last glacial reflect the fluvial sedimentary sequences of South Korea. The stratigraphy of the latest Pleistocene sequences in several fluvial drainage basins includes organic mud layers, intercalated in fluvial deposits, particularly including those on the Soro-ri and Jangheung-ri sites of the Miho River and Nam River, respectively. Research methods included analyses of sedimentary facies,

Ju Yong Kim; Dong Yoon Yang; Wook Hyun Nahm; Sang Heon Yi; Jeong Chan Kim; Se-Sun Hong; Hyun-Su Yun; Jin Young Lee; Jin-Kwan Kim; Keun-Chang Oh; Don-Won Choi

2008-01-01

73

Spectral gradients of downwelling light in a fluvial lake (Lake Saint-Pierre, St-Lawrence River)  

Microsoft Academic Search

Large fluvial lakes are understudied with respect to their underwaterlight climates. Fluvial lakes pose unique challenges for photobiologistsinterested in the interactions amongst light climate, nutrients and microbialcommunity structure and biodiversity. This is because fluvial lakes are typifiedby highly dynamic flow regimes often incorporating different inflows anddischarges each characterized by their own unique physico-chemical composition.These compositional characteristics include the concentrations of

Jean-Jacques Frenette; Michael T. Arts; Jean Morin

2003-01-01

74

From Fundamental Physical Fluvial Processes To River Patterns  

NASA Astrophysics Data System (ADS)

Rivers are ubiquitous on planetary surfaces and their patterns show great variation. The fundamental fluvial processes of flow and sediment transport are relatively well understood, solvable in linearized form and implemented in sophisticated nonlinear numerical models. We successfully modeled formation and evolution of large-scale and long-term patterns that look like braided and meandering river. But what characterizes and discriminates the patterns, and how do the modeled patterns quantitatively compare to natural patterns? Here we focus on characteristics of fluvial bars as building blocks of river patterns. Bars are much larger than grid cells and emerge at length scales predictable by analytical solutions. We used the morphodynamic numerical model Delft3D, which solves the 3D flow and computes sediment transport and bed level change, incorporating the effect of transverse bed slope. We identify bars as connected sand bodies above the average bed level and characterize their shape quantitatively. To reduce computational time and allow high resolution long-term calculations, bed level changes are multiplied by a morphological factor O(100) for each flow time step. This assumes that no significant morphodynamics occur at the time scale in which significant flow takes place. At the moment, desktop computers allow high-resolution century-scale calculations for the largest rivers on Earth. The results show that both meandering and braiding rivers can be modeled by solving the flow and sediment dynamics, and can be characterized by bars. In meandering rivers streamline curvature and bank erosion leads to formation of scroll bars. In braided rivers, large compound bars are formed by merging of unit bars, forming scroll-bars, and smaller compound bars. The results show that nonlinear numerical solution of small-scale flow and sediment transport results in realistic large scale river patterns depending on boundary conditions. As attested by verification in many engineering applications of this model, a second-order (nonlinear) numerical scheme and the transverse bed slope effect are essential for accurate bar dimensions which have not been reproduced in cellular automata. We conclude that a reductionist approach at realistic fluvial landscape modeling is feasible given growing computing power, and successful when evaluated on quantitative characteristics of emergent landforms that compose the landscape.

Schuurman, F.; Kleinhans, M. G.; Geurts, A. H.

2012-12-01

75

Probabilistic approaches to the modelling of fluvial processes  

NASA Astrophysics Data System (ADS)

Fluvial systems generally exhibit sediment dynamics that are strongly stochastic. This stochasticity comes basically from three sources: (a) the variability and randomness in sediment supply due to surface properties and topography; (b) from the multitude of pathways that sediment may take on hillslopes and in channels, and the uncertainty in travel times and sediment storage along those pathways; and (c) from the stochasticity which is inherent in mobilizing sediment, either by heavy rain, landslides, debris flows, slope erosion, channel avulsions, etc. Fully deterministic models of fluvial systems, even if they are physically realistic and very complex, are likely going to be unable to capture this stochasticity and as a result will fail to reproduce long-term sediment dynamics. In this paper I will review another approach to modelling fluvial processes, which grossly simplifies the systems itself, but allows for stochasticity in sediment supply, mobilization and transport. I will demonstrate the benefits and limitations of this probabilistic approach to fluvial processes on three examples. The first example is a probabilistic sediment cascade which we developed for the Illgraben, a debris flow basin in the Rhone catchment. In this example it will be shown how the probability distribution of landslides generating sediment input into the channel system is transposed into that of sediment yield out of the basin by debris flows. The key role of transient sediment storage in the channel system, which limits the size of potential debris flows, is highlighted together with the influence of the landslide triggering mechanisms and climate stochasticity. The second example focuses on the river reach scale in the Maggia River, a braided gravel-bed stream where the exposed sediment on gravel bars is colonised by riparian vegetation in periods without floods. A simple autoregressive model with a disturbance and colonization term is used to simulate the growth and decline in the sediment covered area of the floodplain. The stochastic arrival of floods which erode riparian vegetation is a key ingredient of the dynamics in this model. This example will be used to illustrate how potential effects of flow regulation on sediment dynamics in rivers may statistically be quantified. The third example is a cellular automaton model of individual grain transport and storage in a steep mountain stream which captures the formation and collapse of step-like structures in the channel. In this model stochasticity is included in the input of grains, the probability that individual grains will be blocked by others in transport and form a step, and the probability that that step will collapse. It will be illustrated how this simple model generates complex behaviour in the sediment output, where periods of stasis and sediment storage are punctuated by rapid evacuation of grains as steps collapse. The three examples have one thing in common: the dynamics of sediment output depend not only on stochastic disturbance events but also on the state of the system at the time of the event. Both of these ingredients are needed to statistically describe sediment output in the models, and likely in nature as well. I will conclude by arguing that in the context of stochasticity, traditional notions of stability and equilibrium, of the attribution of cause and effect, and of the timescales of process and form in geomorphic systems, become increasingly difficult.

Molnar, Peter

2013-04-01

76

Fluvial sensitivity to Late Quaternary climate changes in NW Romania  

NASA Astrophysics Data System (ADS)

Fluvial archives became increasingly important for the reconstruction of past environments, as they record a sum of climate, vegetation, hydrologic and anthropic changes. This is especially important for the Late Quaternary, when climate and human activities had recorded large spatial and temporal variations. Here we present a tale of fluvial behavior during the last ca. 24.000 years in NW Romania, based on 1) absolute ages and fluvial architecture of sediments exposed in 8 openings located along the Some?u Mic River, and 2) depth-age models, grain size, LOI and gastropods assemblage analysis on 2 cores located upstream from ?tiucilor Lake, a natural lake along a small tributary of the Some?u Mic River, formed by salt disolution on top of a narrow diapiric anticline. During the Late Glacial (LG), ?tiucilor Lake was more extended then is today, with a high input of coarse materials (sands) from the slopes; and dramatically reducing its size in the Early Holocene, a transition marked by the abrupt occurrence of Holocene gyttja on top of LG sands, 1 km upstream from the present lake. Further upstream, at ca. 4 km from the present day edge of the lake, clays and sandy clays were deposited during the Bolling - Allerod (BA), followed by fine - medium sands of Younger Dryas (YD) age. On top of these sands, clays, sandy clays and gyttja occur, suggesting a returning to a less energetic sedimentary environment in the Holocene. In both cores, the sediments become lacustrine, with clays and fine sands, attesting the expansion of the lake's surface, followed by large fluctuations during the Holocene. The river fed by this stream - Some?u Mic, was a coarse gravel, shallow braided river before the Last Glacial Maximum and until the YD. The channel metamorphosis into a narrow, incised, meandering one, occurred ca. 1500 years after the beginning of the Holocene. However, sedimentological evidences suggest that this transition from braided to meandering channel was not a straightforward one, with a phase of few hundred years during the Early Holocene when the river became a slightly incised braided/wandering channel, with finer in-channel materials. The conservative response of Some?u Mic river to the climatic amelioration, without channel type change during the BA and delayed reaction during the Early Holocene, is probably the consequence of the higher general slope of the valley which maintain an increased solid discharge. This threshold is surpassed only in the Holocene, when deciduous forest arrived in the area and imposed a compact belt at mid altitudes, causing a drastic reduction of solid discharge. Contrary, the small tributary seems to be highly responsive to all important climatic changes during the LG and the Holocene. The two cases confirm the variable sensitivity (depending on geologic and hydrologic factors) of fluvial systems to climate changes and highlight the complexity of their temporal and spatial response to these changes.

Per?oiu, Ioana; R?doane, Maria; Robu, Delia; Tan??u, Ioan

2013-04-01

77

Modeling post-wildfire fluvial incision and terrace formation  

NASA Astrophysics Data System (ADS)

Wildfires often lead to rapid erosion, sedimentation, and morphologic change. One of the challenges in developing quantitative models of post-fire landscape dynamics is a lack of high-quality datasets that document fluvial system evolution in the years to decades following a destructive fire. This study takes advantage of a natural experiment in post-fire fluvial incision to explore how the magnitude and timing of large flow events following a wildfire can change fluvial channel patterns. The study site is the Spring Creek watershed located in the foothills of central Colorado approximately 26 miles southwest of Denver, Colorado. The site burned during the Buffalo Creek wildfire, which was contained in May 1996. Within the Spring Creek watershed, 79% of the basin was burned and 63% of the burned area was considered high severity (Moody and Martin, 2001). In July 1996 a large rain storm hit the burned watershed and 110 mm of rain fell in one hour (Jarrett, 2001). This storm was larger than the estimated 100-year rainfall intensity of 60 mm/hr. Due to the increased surface erodibility after the wildfire, rapid erosion occurred within the watershed, while the main valley of Spring Creek aggraded with up to 2 m of sediment after this storm. Spring Creek has been incising through this post-wildfire sediment since the 1996 storm, and the terraces from this initial storm are still prevalent and identifiable along the valley. Repeated measurements of valley cross-sections since 1996 provide a comprehensive dataset for testing models of fluvial-system evolution on a decadal time scale. We hypothesize that the current channel pattern results from the specific sequence of rain events that occurred within the four years after the initial 1996 storm filled the valley with sediment. This hypothesis was tested using a two-dimensional coupled model of shallow-water flow, sediment transport, and topographic evolution. Discharge data were obtained from a stream gage installed at Spring Creek in 1997, with records from April 1997 to October 2000. The initial channel topography was constructed by extrapolating the 1996 terraces across the channel. Thus the initial condition for the model is the aggradation after the 1996 storm. We calibrated the model using observed measured discharges and actual closely spaced (10-50 m) cross-sections that were measured before and after large discharges from 1997-2000. Model sensitivity tests are used to explore how the channel evolution might have differed under alternative discharge sequences. For example, the natural discharge from the study site showed three large floods in 1997, two in 1998, one in 1999, and none in 2000. We ran models that varied this sequence to identify the degree to which storm sequence, magnitude, and duration influence the tempo and nature of channel evolution. Early results show that the sequence of storms is indeed important in shaping the overall channel geomorphology.

Rengers, F. K.; Tucker, G. E.

2013-12-01

78

Episodes of fluvial and volcanic activity in Mangala Valles, Mars  

NASA Astrophysics Data System (ADS)

A new mapping-based study of the 900-km-long Mangala Valles outflow system was motivated by the availability of new high-resolution images and continued debates about the roles of water and lava in outflow channels on Mars. This study uses photogeologic analysis, geomorphic surface mapping, cratering statistics, and relative stratigraphy. Results show that Mangala Valles underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian. The occurrence of scoured bedrock at the base of the mapped stratigraphy, in addition to evidence provided by crater retention ages, suggests that fluvial activity preceded the deposition of two of the volcanic units. Crater counts performed at 30 locations throughout the area have allowed us to construct the following timeline: (1) formation of Noachian Highlands and possible initial flooding event(s) before ?1 Ga, (2) emplacement of Tharsis lava flows in the valley from ?700 to 1000 Ma, (3) a megaflooding event at ?700-800 Ma sourced from Mangala Fossa, (4) valley fill by a sequence of lava flows sourced from Mangala Fossa ?400-500 Ma, (5) another megaflooding event from ?400 Ma, (6) a final phase of volcanism sourced from Mangala Fossa ?300-350 Ma, and (7) emplacement of eolian sedimentary deposits in the northern portion of the valley ?300 Ma. These results are consistent with alternating episodes of aqueous flooding and volcanism in the valles. This pattern of geologic activity is similar to that of other outflow systems, such as Kasei Valles, suggesting that there is a recurring, and perhaps coupled, nature of these processes on Mars.

Keske, Amber L.; Hamilton, Christopher W.; McEwen, Alfred S.; Daubar, Ingrid J.

2015-01-01

79

Fluvial process and the establishment of bottomland trees  

NASA Astrophysics Data System (ADS)

The effects of river regulation on bottomland tree communities in western North America have generated substantial concern because of the important habitat and aesthetic values of these communities. Consideration of such effects in water management decisions has been hampered by the apparent variability of responses of bottomland tree communities to flow alteration. When the relation between streamflow and tree establishment is placed in a geomorphic context, however, much of that variability is explained, and prediction of changes in the tree community is improved. The relation between streamflow and establishment of bottomland trees is conditioned by the dominant fluvial process or processes acting along a stream. For successful establishment, cottonwoods, poplars, and willows require bare, moist surfaces protected from disturbance. Channel narrowing, channel meandering, and flood deposition promote different spatial and temporal patterns of establishment. During channel narrowing, the site requirements are met on portions of the bed abandoned by the stream, and establishment is associated with a period of low flow lasting one to several years. During channel meandering, the requirements are met on point bars following moderate or higher peak flows. Following flood deposition, the requirements are met on flood deposits ;high above the channel bed. Flood deposition can occur along most streams, but where a channel is constrained by a narrow valley, this process may be the only mechanism that can produce a bare, moist surface high enough to be safe from future disturbance. Because of differences in local bedrock, tributary influence, or geologic history, two nearby reaches of the same stream may be dominated by different fluvial processes and have different spatial and temporal patterns of trees. We illustrate this phenomenon with examples from forests of plains cottonwood ( Populus deltoides ssp. monilifera) along meandering and constrained reaches of the Missouri River in Montana.

Scott, Michael L.; Friedman, Jonathan M.; Auble, Gregor T.

1996-01-01

80

Dynamic Flocculation of Muds in Fluvial to Marine Transitions  

NASA Astrophysics Data System (ADS)

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.

Keyvani, A.; Strom, K. B.

2012-12-01

81

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

SciTech Connect

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.

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

2008-01-01

82

Publicaciones del IGME: serie Hidrogeologa y aguas subterrneas, n 14. VI Simposio del Agua en Andaluca. II: 1.237-1.245  

E-print Network

aguas superficiales, subterráneas y residuales Sánchez Díaz, Luis* y Castillo Martín, Antonio, aguas superficiales, residuales y subterráneas RESUMEN En esta contribución se expone la calidad general que presentaron las aguas superficiales, subterráneas y residuales de la Vega de Granada durante 2003

Castillo, Antonio

83

Bottomland vegetation distribution along Passage Creek, Virginia, in relation to fluvial landforms.  

USGS Publications Warehouse

Persistent distribution patterns of woody vegetation within the bottomland forest of Passage Creek, Virginia, were related to fluvial landforms, channel geometry, streamflow characteristics, and sediment-size characteristics. Distinct species distributional patterns were found on four common fluvial geomorphic landforms: depositional bar, active-channel shelf, floodplain, and terrace. Independent hydrologic characteristics (flow duration and flood frequency) were determined for each of the landforms. Vegetation patterns appear to develop more as a result of hydrologic processes associated with each fluvial landform rather than from sediment-size characteristics. -from Authors

Hupp, C.R.; Osterkamp, W.R.

1985-01-01

84

Maintaining channel abandonment processes increases riparian plant diversity within fluvial corridors  

E-print Network

Maintaining channel abandonment processes increases riparian plant diversity within fluvial dynamic alluvial riverine corridors, abandoned channels form and experience hydrogeomorphic processes diversity and community dynamics along terrestrializing abandoned channels have received much less attention

Battles, John

85

Acquisition, 3-D display and interpretation of GPR data in fluvial sedimentology.  

E-print Network

??Alluvial architecture has an inherently three-dimensional character; however, standard methods used within fluvial sedimentology, including ground penetrating radar (GPR) surveys, generally provide only 1-D or (more)

Zuk, Tomasz

2011-01-01

86

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

E-print Network

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

Paola, Chris

87

Evolution of fluvial systems in salt-walled mini-basins: A review and new insights  

NASA Astrophysics Data System (ADS)

The preserved sedimentary expression of fluvial successions accumulated in salt-walled mini-basins records the complex history of basin subsidence, the style of sediment supply, and the pattern of sediment distribution in response to a range of fluvial processes throughout the evolution of such basins. Temporal and spatial variations in the rate of basin subsidence govern the generation of accommodation space, whereas the rate and style of sediment supply govern how available accommodation is filled; together these parameters act as principal controls that dictate the gross-scale pattern of fluvial sedimentation. Additional factors that influence fluvial stratigraphic architecture in salt-walled mini-basins are: (i) the trend and form of inherited basement lineations and faults that control the geometry, orientation and spacing of salt walls that develop in response to halokinesis; (ii) salt thickness and composition that dictate both the maximum potential basin-fill thickness within a developing mini-basin and the rate of evacuation (migration) of salt from beneath evolving mini-basins, leading to the growth of confining salt walls, uplift of which may generate surface topographic expression that influences fluvial drainage patterns; (iii) climate that dictates fluvial style and the processes by which sediment is distributed; and (iv) the inherited direction of drainage relative to the trend of elongate salt walls and locus of sediment supply that dictates how sediments are distributed both within a single mini-basin and between adjacent basins. Examples of fluvial sedimentary architectures preserved in salt-walled mini-basins from a number of geographic regions are used to illustrate and document the primary controls that influence patterns of fluvial sediment accumulation. The distribution of fluvial architectural elements preserved within mini-basins follows a predictable pattern, both within individual basin depocentres and between adjoining basins: drainage pathways preferentially migrate to topographic lows within basins, such as developing rim-synclines, and away from topographic highs, such as uplifting salt walls or developing turtle-back structures. This paper demonstrates a range of fluvial-halokinetic interactions through consideration of a series of case studies, which demonstrate the current understanding of fluvial response to salt-walled mini-basin evolution and which highlight gaps in the current understanding.

Banham, Steven G.; Mountney, Nigel P.

2013-10-01

88

Analysis of Ancient Fluvial Patterns on the Surface of Mars  

NASA Technical Reports Server (NTRS)

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.

Jethani, Henna; Williams, M. E.

2010-01-01

89

What can we learn from fluvial incision in high mountains?  

NASA Astrophysics Data System (ADS)

High and actively deforming mountain ranges attract the attention of geoscientists as they provide natural laboratories of fast evolving process-response systems. Tectonic compressional settings, often linked to perpendicular extension, control the topographic growth and hence, erosion, transport pathways and sedimentation. High altitude differences within short horizontal distances promote material re-organisation and high rates of surface processes. Furthermore, high mountains constitute orographic barriers that affect atmospheric circulations as well as host different climate regimes similar to those of widely separated latitudinal belts. Both cause a high sensitivity of surface processes to changes in climatic conditions. However, feedbacks between climatic and tectonic forcing are complex. Additionally, the dominance of one or the other varies in space and also over time, inheriting various traces of the paleo-morphodynamic conditions to the subsequent process regimes. To unravel the forces driving the evolution of relief in active mountains, numerous studies employ the drainage network of the corresponding mountains as a proxy of landscape evolution. Especially the rates of river incision provide a powerful tool to characterize the surface response and infer causes behind it. Several parameters of river incision are available to describe the fluvial incision at individual sites (e.g. terrace incision rates), along the river course (e.g. longitudinal river profiles, Hack index) and in its perpendicular dimension (e.g. valley cross sections, valley shape ratios). But they require careful interpretation. They are sensitive to both, climatic and tectonic forcing. Therefore, the synopsis of such indices for fluvial incision is essential to evaluate the role of climatic versus tectonic forcing. Here, we use the Panj river system, the major river draining the Pamir mountains of Central Asia, as an example. The Panj experiences high altitude changes of more than 4000 m and deflects several times from the main river orientation, where it cuts through major deformation zones and dome structures of the Pamir. Our contribution discusses the potentials and limitations of river incision analysis. We infer climatic versus tectonic forcing based on terraces along the Panj river together with the indication from its longitudinal profile, Hack index and valley shape ratios.

Fuchs, Margret; Gloaguen, Richard; Krbetschek, Matthias

2013-04-01

90

3D Geologic and Reservoir Modelling of a Distributive Fluvial System Derived from lidar: A Case Study of the Huesca Fluvial Fan.  

NASA Astrophysics Data System (ADS)

Understanding stratigraphic and depositional architecture in a fluvially dominated system is fundamental when trying to model and characterise properties such as geometric relationships, heterogeneity, lithologic patterns or trends of the system as well as any associated petrophysical properties or behaviours. The Huesca fluvial fan, an Oligocene - Miocene age Distributive Fluvial System (DFS) in the northern extent of the Ebro Basin, is used extensively as an outcrop analogue for modelling fluvial hydrocarbon reservoirs, as well as a base for the DFS model. To further improve understanding of the system, mapping techniques using lidar integrated with Differential Global Navigation Satellite System (DGNSS) measurements were used to create sub-metre (spatially) accurate geologic models of the medial-distal portions of the DFS. In addition to the digital terrain data, traditional field sedimentary logs, structural and palaeocurrent measurements, and samples for petrophysical analysis were also collected near the town of Piracs in a series of amphitheatres and canal cuts that expose excellent two and three-dimensional views of the strata. The geologic models and subsequent analyses derived from the data will provide a quantitative tool to further understand the depositional architecture, geometric relationship and lithologic characteristics across the studied portion of the distributive fluvial system. Utilizing the inherent quantitative nature of the terrain data in combination with the traditional field and sample data collected, an outcrop based geocellular model of the studied section can be constructed by using several geostatistical modelling approaches to describe geo-body geometries (thickness and width ratio) for the associated fluvial architecture, as well as facies distribution and observed petrophysical characteristics. The resolution of the digital terrain data (<10cm) allowed for an accurate integration of the field observations (palaeoflow, sedimentary structures and grain size distributions) into a more complete model of studied portion of the fluvial system. The three-dimensionality of the exposure lends itself well to using lidar as a tool when mapping geo-body geometry and architecture across several kilometres. This approach leads to more accurate, quantitative reservoir and depositional models of the distributive fluvial system.

Burnham, Brian; Hodgetts, David; Redfern, Jonathan

2014-05-01

91

Geomorphic evolution of the Martian highlands through ancient fluvial processes  

NASA Astrophysics Data System (ADS)

The evolution of crater degradation in the Martian highlands based on variations in crater morphology is traced. The timing of this process related to geology, elevation, and latitude is examined, the nature of fluvial resurfacing is studied, and the approximate rate of denudation is determined. The obtained data make it possible to understand the early geologic history of Mars, the interaction between the atmosphere and surface processes through time, and the nature of highland surface materials. Degradation was found to begin with sheet-flooding and the formation of runoff channels in both the interior and exterior of the craters. Progressive stripping of the ejecta material led to craters with incised rims. Erosion and infilling led to flat doors. With time, continued erosion removed ejecta and rim materials completely. Timing of degradation based on cumulative size-frequency distribution curves of highland crater population indicates that the process ceased completely in the late Hesperian. Global average denudation rates were found to be between 0.0001 and 0.005 mm/yr.

Craddock, R. A.; Maxwell, T. A.

1993-02-01

92

Microbiological and geochemical characterization of fluvially deposited sulfidic mine tailings  

SciTech Connect

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.

Wielinga, B.; Lucy, J.K.; Moore, J.N.; Seastone, O.F.; Gannon, J.E. [Univ. of Montana, Missoula, MT (United States)

1999-04-01

93

Characterization of fluvial sedimentology for reservoir simulation modeling  

SciTech Connect

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.

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

1990-09-01

94

Impactos del Huracn Isaac en la calidad del agua en Luisiana con MODIS 250m  

E-print Network

lluvias. Por tal razón se quiere estudiar la calidad del agua en el delta del río Mississippi antes1 Impactos del Huracán Isaac en la calidad del agua en Luisiana con MODIS 250m Thais J. Alicea imágenes en ENVI. Palabras clave: Calidad del agua, ENVI, Isaac, Luisiana, MODIS

Gilbes, Fernando

95

ALTERNATIVAS DE REUTILIZACIN DE AGUAS RESIDUALES REGENERADAS EN SISTEMAS DE TRATAMIENTO DE LA PENNSULA DE PARAGUAN  

Microsoft Academic Search

Esta investigacin tuvo como objetivo proponer alternativas de reutilizacin del agua regenerada por los Sistemas de Tratamiento de Aguas Residuales Domesticas existentes en la Pennsula de Paraguana. La investigacin inicio con la identificacin de los Sistemas de Tratamiento de Aguas Residuales Domesticas existentes en la Pennsula de Paraguana, se realizaron visitas para describir la situacin actual de los Sistemas. Adems,

Maria Beatriz Bracho; Zuleima Escalona; Roberto Garcia

2008-01-01

96

Alternativas de reutilizacin de aguas residuales regeneradas en sistemas de tratamiento de la pennsula de Paraguan  

Microsoft Academic Search

Esta investigacin tuvo como objetivo proponer alternativas de reutilizacin del agua regenerada por los Sistemas de Tratamiento de Aguas Residuales Domesticas existentes en la Pennsula de Paraguana. La investigacin inicio con la identificacin de los Sistemas de Tratamiento de Aguas Residuales Domesticas existentes en la Pennsula de Paraguana, se realizaron visitas para describir la situacin actual de los Sistemas. Adems,

Maria Beatriz Bracho; Zuleima Escalona; Roberto Garcia

2008-01-01

97

Sequence stratigraphic architecture of a differentially subsiding bay to fluvial basin: the Eocene Ishikari Group, Ishikari Coal Field, Hokkaido, Japan  

Microsoft Academic Search

The Eocene Ishikari Group, deposited in a bay to fluvial basin in central Hokkaido, Japan, provides important information on fluvial sequence stratigraphy in a differentially subsiding ocean-connected setting. The Ishikari Group consists of four million-year-order depositional sequences (Isk-1, Isk-2, Isk-3 and Isk-4), composed mainly of meandering\\/braided fluvial systems. Each depositional sequence contains marine or lacustrine incursion beds, which show lake

Osamu Takano; Amane Waseda

2003-01-01

98

Fluvial erosion and post-erosional processes on Titan  

USGS Publications Warehouse

The surface of Titan has been revealed by Cassini observations in the infrared and radar wavelength ranges as well as locally by the Huygens lander instruments. Sand seas, recently discovered lakes, distinct landscapes and dendritic erosion patterns indicate dynamic surface processes. This study focus on erosional and depositional features that can be used to constrain the amount of liquids involved in the erosional process as well as on the compositional characteristics of depositional areas. Fluvial erosion channels on Titan as identified at the Huygens landing site and in RADAR and Visible and Infrared Mapping Spectrometer (VIMS) observations have been compared to analogous channel widths on Earth yielding average discharges of up to 1600 m3/s for short recurrence intervals that are sufficient to move centimeter-sized sediment and significantly higher discharges for long intervals. With respect to the associated drainage areas, this roughly translates to 1-150 cm/day runoff production rates with 10 years recurrence intervals and by assuming precipitation this implies 0.6-60 mm/h rainfall rates. Thus the observed surface erosion fits with the methane convective storm models as well as with the rates needed to transport sediment. During Cassini's T20 fly-by, the VIMS observed an extremely eroded area at 30?? W, 7?? S with resolutions of up to 500 m/pixel that extends over thousands of square kilometers. The spectral characteristics of this area change systematically, reflecting continuous compositional and/or particle size variations indicative of transported sediment settling out while flow capacities cease. To account for the estimated runoff production and widespread alluvial deposits of fine-grained material, release of area-dependent large fluid volumes are required. Only frequent storms with heavy rainfall or cryovolcanic induced melting can explain these erosional features. ?? 2008 Elsevier Inc.

Jaumann, R.; Brown, R.H.; Stephan, K.; Barnes, J.W.; Soderblom, L.A.; Sotin, C.; Le, Mouelic S.; Clark, R.N.; Soderblom, J.; Buratti, B.J.; Wagner, R.; McCord, T.B.; Rodriguez, S.; Baines, K.H.; Cruikshank, D.P.; Nicholson, P.D.; Griffith, C.A.; Langhans, M.; Lorenz, R.D.

2008-01-01

99

Marine intervals in Neogene fluvial deposits of western Amazonia  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

100

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

USGS Publications Warehouse

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.

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

2011-01-01

101

Fluvial processes in eastern Hellas Planitia, Mars - Insights from crater counts  

NASA Astrophysics Data System (ADS)

With a diameter of 2,300 km and a depth of more than 8,000 m, the Hellas basin is one of the major geomorphic and topographic features in the southern Martian hemisphere. It has been acting as a depositional sink since its formation 4 Ga ago [1] and has been the location of a wide variety of geologic processes. In this ongoing study, we investigated the stratigraphy of fluvial features in the eastern Hellas region on Mars, focusing on apparently young fluvial depositional areas in the Dao and Harmakhis Valles region and on the eastern plains within the Hellas basin. The region connecting Hesperia Planum with Hellas Planitia is characterized by a patchwork of remnant massifs protruding through a set of plains units of varying morphology and surface texture, indicating a diverse and eventful geologic history. A variety of geologic processes has been observed, from the basin-forming Hellas impact, widespread plainsforming and central vent volcanism [2,3] to fluvial and cold climate processes [3,4]. In order to analyze the stratigraphy, we performed crater counts for selected areas to obtain absolute ages for young areas formed by fluvial processes. We also obtained a lower limit for the age of major fluvial processes.

Zuschneid, W.; van Gasselt, S.

2014-04-01

102

Neotectonics and fluvial geomorphology of the Northern Sinai Peninsula  

NASA Astrophysics Data System (ADS)

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.

Kusky, T.; El-Baz, F.

2000-08-01

103

Biomarkers in Transit Reveal the Nature of Fluvial Integration  

NASA Astrophysics Data System (ADS)

The carbon and hydrogen isotopic composition of vascular plant leaf waxes are common proxies for hydrologic and vegetation change. Sedimentary archives off major river systems are prime targets for continental paleoclimate studies under the assumption that rivers integrate changes in terrestrial organic carbon (OC) composition over their drainage basin. However, the proportional contribution of sources within the basin (e.g. head waters vs. floodplain) and the transit times of OC through the fluvial system remain largely unknown. This lack of quantifiable information about the proportions and timescales of integration within large catchments poses a challenge for paleoclimate reconstructions. To examine the sources of terrestrial OC eroded and supplied to a river system and the spatial distribution of these sources, we use compound specific isotope analysis (i.e. ?13C, ?14C, and ?D) on plant-derived leaf waxes, filtered from large volumes of river water (20-200L) along a major river system. We selected the Kosipata River that drains the western flank of the Andes in Peru, joins the Madre de Dios River across the Amazonian floodplain, and ultimately contributes to the Amazon River. Our study encompassed an elevation gradient of >4 km, in an almost entirely forested catchment. Precipitation ?D values vary by >50 due to the isotopic effect of elevation, a feature we exploit to identify the sources of plant wax n-alkanoic acids transported by the river. We used the ?D plant wax values from tributary rivers as source constrains and the main stem values as the integrated signal. In addition, compound specific radiocarbon on individual chain length n-alkanoic acids provide unprecedented detail on the integrated age of these compounds. Preliminary results have established that 1) most of the OC transport occurs in the wet season; 2) total carbon transport in the Madre de Dios is dominated by lowland sources because of the large floodplain area, but initial data suggest that OC from high elevations may be proportionally overrepresented relative to areal extent, with possibly important implications for biomarker isotope composition; 3) timescales of different biomarkers vary considerably; 4) the composition of OC varies downstream and with depth stratification within large rivers. We filtered >1000L of river water in this remote location during the wet season, and are presently replicating that study during the dry season, providing a seasonal comparison of OC transport in this major river system.

Ponton, C.; West, A.; Feakins, S. J.; Galy, V.

2013-12-01

104

The Pleistocene climate-controlled fluvial sedimentary record in the Be?chatw mine (central Poland)  

NASA Astrophysics Data System (ADS)

Sedimentological analyses of fluvial formations in the Be?chatw mine have yielded results that have more than regional significance. They concern the reaction of rivers to climatic changes in the Pleistocene. Changes in river geometry and their depositional records are examined from two fluvial formations. These formations represent different times, but show similar palaeoenvironmental changes. Cool temperate climate conditions resulted in meandering (or anastomosing) river sedimentation, which was controlled by equalized precipitation and by a well-developed vegetation cover. Cold periglacial climate conditions resulted in braided river sedimentation immediately before the Glacial Maximum, with high discharges and a high sediment load. The palaeoclimatic and palaeohydrologic analyses of the Weichselian fluvial deposits in Be?chatw provide additional information to that from similar studies in Germany and the Netherlands, thus jointly resulting in a consistent palaeogeographic model of western-middle Europe.

Zieli?ski, Tomasz

2007-01-01

105

A 100 ka record of fluvial activity in the Fitzroy River Basin, tropical northeastern Australia  

NASA Astrophysics Data System (ADS)

This study reports the nature and timing of Quaternary fluvial activity in the Fitzroy River basin, which drains a diverse 143,000 km 2 area in northeastern Queensland, before discharging into the Great Barrier Reef Marine Park. The catchment consists of an extensive array of channel and floodplain types that we show have undergone large-scale fluvial adjustment in-channel planform, geometry and sinuosity. Optically stimulated luminescence (OSL) dating of quartz sediments from fifteen (3-18 m) floodplain cores throughout the basin indicates several discrete phases of active bedload activity: at 105-85 ka in Marine Isotope Stage (MIS) 5, at 50-40 ka (MIS 3), and at 30-10 ka (MIS 3/2). The overall timing of late Quaternary fluvial activity correlates well with previous accounts from across Australia with rivers being primarily active during interstadials. Fluvial activity, however, does not appear to have been synchronous throughout the basin's major sub-catchments. Fluvial activity throughout MIS 2 (i.e. across the Last Glacial Maximum) in the meandering channels of the Fitzroy correlates well with regional data in tropical northeastern Queensland, and casts new light on the river response to reduced rainfall and vegetation cover suggested by regional palaeoclimate indicators. Moreover, the absence of a strong Holocene signal is at odds with previous accounts from elsewhere throughout Australia. The latitudinal position of the Fitzroy across the Tropic of Capricorn places this catchment at a key location for elucidating the main hydrological drivers of Quaternary fluvial activity in northeastern Australia, and especially for determining tropical moisture sources feeding into the headwaters of Cooper Creek, a major river system of the continental interior.

Croke, Jacky; Jansen, John D.; Amos, Kathryn; Pietsch, Timothy J.

2011-06-01

106

Deep instability of deforested tropical peatlands revealed by fluvial organic carbon fluxes.  

PubMed

Tropical peatlands contain one of the largest pools of terrestrial organic carbon, amounting to about 89,000 teragrams (1?Tg is a billion kilograms). Approximately 65 per cent of this carbon store is in Indonesia, where extensive anthropogenic degradation in the form of deforestation, drainage and fire are converting it into a globally significant source of atmospheric carbon dioxide. Here we quantify the annual export of fluvial organic carbon from both intact peat swamp forest and peat swamp forest subject to past anthropogenic disturbance. We find that the total fluvial organic carbon flux from disturbed peat swamp forest is about 50 per cent larger than that from intact peat swamp forest. By carbon-14 dating of dissolved organic carbon (which makes up over 91 per cent of total organic carbon), we find that leaching of dissolved organic carbon from intact peat swamp forest is derived mainly from recent primary production (plant growth). In contrast, dissolved organic carbon from disturbed peat swamp forest consists mostly of much older (centuries to millennia) carbon from deep within the peat column. When we include the fluvial carbon loss term, which is often ignored, in the peatland carbon budget, we find that it increases the estimate of total carbon lost from the disturbed peatlands in our study by 22 per cent. We further estimate that since 1990 peatland disturbance has resulted in a 32 per cent increase in fluvial organic carbon flux from southeast Asia--an increase that is more than half of the entire annual fluvial organic carbon flux from all European peatlands. Our findings emphasize the need to quantify fluvial carbon losses in order to improve estimates of the impact of deforestation and drainage on tropical peatland carbon balances. PMID:23364745

Moore, Sam; Evans, Chris D; Page, Susan E; Garnett, Mark H; Jones, Tim G; Freeman, Chris; Hooijer, Aljosja; Wiltshire, Andrew J; Limin, Suwido H; Gauci, Vincent

2013-01-31

107

Fluvial Channel Networks as Analogs for the Ridge-Forming Unit, Sinus Meridiani, Mars  

NASA Technical Reports Server (NTRS)

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.

Wilkinson, M. J.; du Bois, J. B.

2010-01-01

108

Ridge Orientations of the Ridge-Forming Unit, Sinus Meridiani, Mars-A Fluvial Explanation  

NASA Technical Reports Server (NTRS)

Imagery and MOLA data were used in an analysis of the ridge-forming rock unit (RFU) exposed in Sinus Meridiani (SM). This unit shows parallels at different scales with fluvial sedimentary bodies. We propose the terrestrial megafan as the prime analog for the RFU, and likely for other members of the layered units. Megafans are partial cones of fluvial sediment, with radii up to hundreds of km. Although recent reviews of hypotheses for the RFU units exclude fluvial hypotheses [1], inverted ridges in the deserts of Oman have been suggested as putative analogs for some ridges [2], apparently without appreciating The wider context in which these ridges have formed is a series of megafans [3], a relatively unappreciated geomorphic feature. It has been argued that these units conform to the megafan model at the regional, subregional and local scales [4]. At the regional scale suites of terrestrial megafans are known to cover large areas at the foot of uplands on all continents - a close parallel with the setting of the Meridiani sediments at the foot of the southern uplands of Mars, with its incised fluvial systems leading down the regional NW slope [2, 3] towards the sedimentary units. At the subregional scale the layering and internal discontinuities of the Meridiani rocks are consistent, inter alia, with stacked fluvial units [4]. Although poorly recognized as such, the prime geomorphic environment in which stream channel networks cover large areas, without intervening hillslopes, is the megafan [see e.g. 4]. Single megafans can reach 200,000 km2 [5]. Megafans thus supply an analog for areas where channel-like ridges (as a palimpsest of a prior landscape) cover the intercrater plains of Meridiani [6]. At the local, or river-reach scale, the numerous sinuous features of the RFU are suggestive of fluvial channels. Cross-cutting relationships, a common feature of channels on terrestrial megafans, are ubiquitous. Desert megafans show cemented paleo-channels as inverted topography [4] with all these characteristics.

Wilkinson, M. Justin; Herridge, A.

2013-01-01

109

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

110

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

SciTech Connect

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.

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

1989-03-01

111

Gone But Not Forgotten: The Aeolian Modification of Fluvial Surfaces on Mars: Preliminary Results from Central Australia  

NASA Technical Reports Server (NTRS)

MOC images indicate that aeolian ridges may mask and even obliterate primary depositional surfaces on Mars. This modification increases the difficulty in mapping the recent geological history of the planet. An analogue study in central Australia demonstrates how patterns in aeolian dunes, formed over abandoned fluvial surfaces, can be used to detect buried fluvial features.

Bourke, M. C.

2003-01-01

112

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

E-print Network

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

Cowie, Patience

113

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

E-print Network

i Identifying Complex Fluvial Sandstone Reservoirs Using Core, Well Log, and 3D Seismic Data All Rights Reserved #12;ii ABSTRACT Identifying Complex Fluvial Sandstone Reservoirs Using Core, Well the stratigraphic distribution and lateral extent of potential gas-bearing channel sandstone reservoirs

Seamons, Kent E.

114

Crater degradation in the Martian highlands: Morphometric analysis of the Sinus Sabaeus region and simulation modeling suggest fluvial  

E-print Network

modeling indicates that craters fill rapidly at first, but the rate of infilling diminishes through time and simulation modeling suggest fluvial processes Nancy K. Forsberg-Taylor1 and Alan D. Howard Department] Results from simulation modeling of crater degradation by fluvial and eolian processes are compared

Howard, Alan D.

115

Fluviale kanaler fra et stort vre kretassisk delta ved Pautfit, Vestgr~nland; sandlegemegeometri og kanalmorfologi  

Microsoft Academic Search

(. san, shale and coal seams are here very well exposed in a series of steep sided gullies. The investigations were focused on an analysis of the sand-body geometry and the fluvial style of the different types af channels. The use of an advanced photogrammetric system during the investigations enabled the construction of precise vertical sections of the exposures, which

TORBEN OLSEN

116

Hydrocarbon accumulation in basal Pennsylvanian fluvial sandstone near Hardinville, Crawford County, Illinois: a model paleogeomorphic trap  

Microsoft Academic Search

The surface of the Mississippian-Pennsylvanian unconformity in the Illinois basin is characterized by an anastomosing pattern of paleovalleys eroded by the ancient Michigan River system. Fluvial sandstones deposited within these valleys commonly were buried by transgressive Pennsylvanian marine shales, creating the potential for stratigraphic entrapment of hydrocarbons. One such trap was discovered accidentally on the northeast flank of the Hardinville

R. H. Howard; S. T. Whitaker

1987-01-01

117

LANDSCAPE PERCEPTION IN FLUVIAL ECOLOGICAL RESTORATION PROJECTS: CONTRIBUTIONS AND PERSPECTIVES FOR THE  

E-print Network

1 LANDSCAPE PERCEPTION IN FLUVIAL ECOLOGICAL RESTORATION PROJECTS: CONTRIBUTIONS AND PERSPECTIVES of a pluridisciplinary research, through the example of the restoration projects of floodplain lakes of the Rhône and Ain restoration projects Until now, restoration objectives have essentially consisted in re

Paris-Sud XI, Université de

118

Misconceptions about mechanical and fluvial erosional strength: implications to streambank stability  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

119

Late Cenozoic fluvial successions in northern and western India: an overview and synthesis  

NASA Astrophysics Data System (ADS)

Late Cenozoic fluvial successions are widespread in India. They include the deposits of the Siwalik basin which represent the accumulations of the ancient river systems of the Himalayan foreland basin. Palaeomagnetic studies reveal that fluvial architecture and styles of deposition were controlled by Himalayan tectonics as well as by major climatic fluctuations during the long (?13 Ma) span of formation. The Indo-Gangetic plains form the world's most extensive Quaternary alluvial plains, and display spatially variable controls on sedimentation: Himalayan tectonics in the frontal parts, climate in the middle reaches, and eustasy in the lower reaches close to the Ganga-Brahmaputra delta. Climatic effects were mediated by strong fluctuations in the SW Indian Monsoon, and Himalayan rivers occupy deep valleys in the western Ganga plains where stream power is high, cut in part during early Holocene monsoon intensification; the broad interfluves record the simultaneous aggradation of plains-fed rivers since ?100 ka. The eastward increase in precipitation across the Ganga Plains results in rivers with low stream power and a very high sediment flux, resulting in an aggradational mode and little incision. The river deposits of semi-arid to arid western India form important archives of Quaternary climate change through their intercalation with the eolian deposits of the Thar Desert. Although the synthesis documents strong variability-both spatial and temporal-in fluvial stratigraphy, climatic events such as the decline in precipitation during the Last Glacial Maximum and monsoon intensification in the early Holocene have influenced fluvial dynamics throughout the region.

Sinha, R.; Kumar, R.; Sinha, S.; Tandon, S. K.; Gibling, M. R.

2007-11-01

120

Fluvial history of the Rio Ilave valley, Peru, and its relationship to climate and human history  

Microsoft Academic Search

Fluvial strata and landforms in the Rio Ilave valley (Peru) document a history of Holocene aggradation and downcutting that is correlative with regional climatic events and provides an environmental context for human occupation of the river valley. Periods of aggradation correspond to periods of high (or rising) level in Lake Titicaca and elsewhere on the Altiplano, and increased sediment accumulation

Catherine A. Rigsby; Paul A. Baker; Mark S. Aldenderfer

2003-01-01

121

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

E-print Network

and fluvial response in the Tachia River, central Taiwan, documents highly episodic sediment supply over by decadal-scale and century-scale longitudinal river profile data spanning 1904 to 2008 and by sediment reserved. 1. Introduction Rivers receive episodic inputs of sediment, and sediment delivery to downstream

Montgomery, David R.

122

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

Microsoft Academic Search

A mechanistic model is derived for the rate of fluvial erosion into bedrock by abrasion from uniform size particles that impact the bed during transport in both 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

Michael P. Lamb; William E. Dietrich; Leonard S. Sklar

2008-01-01

123

Study on detailed geological modelling for fluvial sandstone reservoir in Daqing oil field  

SciTech Connect

Guided by the sedimentation theory and knowledge of modern and ancient fluvial deposition and utilizing the abundant information of sedimentary series, microfacies type and petrophysical parameters from well logging curves of close spaced thousands of wells located in a large area. A new method for establishing detailed sedimentation and permeability distribution models for fluvial reservoirs have been developed successfully. This study aimed at the geometry and internal architecture of sandbodies, in accordance to their hierarchical levels of heterogeneity and building up sedimentation and permeability distribution models of fluvial reservoirs, describing the reservoir heterogeneity on the light of the river sedimentary rules. The results and methods obtained in outcrop and modem sedimentation studies have successfully supported the study. Taking advantage of this method, the major producing layers (PI{sub 1-2}), which have been considered as heterogeneous and thick fluvial reservoirs extending widely in lateral are researched in detail. These layers are subdivided into single sedimentary units vertically and the microfacies are identified horizontally. Furthermore, a complex system is recognized according to their hierarchical levels from large to small, meander belt, single channel sandbody, meander scroll, point bar, and lateral accretion bodies of point bar. The achieved results improved the description of areal distribution of point bar sandbodies, provide an accurate and detailed framework model for establishing high resolution predicting model. By using geostatistic technique, it also plays an important role in searching for enriched zone of residual oil distribution.

Zhao Hanqing; Fu Zhiguo; Lu Xiaoguang [Institute of Petroleum Exploration and Development, Daqing (China)

1997-08-01

124

Architecture and origin of an amalgamated fluvial sheet sand, lower Castlegate Formation, Book Cliffs, Utah  

Microsoft Academic Search

Amalgamated, fluvial sheet sandstones in the stratigraphic record are often interpreted as the deposits of braided rivers. Alluvial sequence stratigraphic models show these sheet sandstones overlying sequence boundaries and deposited during low rates of base level rise and fall. Since sequence stratigraphic models rely on the balance between creation\\/destruction of accommodation and sediment supply, is the sheet-like nature of these

Brett T. McLaurin; Ron J. Steel

2007-01-01

125

Facies architecture in a fluvial-deltaic sequence, upper Crooked Fork Group (Pennsylvanian), Tennessee and Kentucky  

SciTech Connect

The upper Crooked Fork Group on the Cumberland plateau in northeastern Tennessee and southeastern Kentucky includes the Wartburg Sandstone (Corbin of Kentucky) and surrounding fine-grained strata of the Breathitt Formation below the Poplar Creek Coal. Detailed study of outcrops employs lateral profiles and architectural element analysis. Examination of bounding surfaces within and between elements indicates a sixfold hierarchy based on areal extent and geometry. The Wartburg Sandstone consists largely of three-dimensional macroform bar complexes. Foreset macroform elements predominate, with minor lateral accretion elements present and no apparent internal cyclicity. The channelized base of the Wartburg, predominance of large-scale planar and trough cross-stratification, low paleocurrent variance, and presence of soft-sediment deformation elements and massive sandstone elements with large mudstone intraclasts suggest a low-sinuosity fluvial setting. Strata overlying the Wartburg display fine-grained lateral accretion elements and associated overbank-fines. This suggests an upward change in fluvial style in the upper Crooked Fork Group from a predominantly coarse-grained low-sinuosity setting to a fine-grained high-sinuosity setting. The abundance of downstream and lateral accretion elements, plant debris, rooting, and thin discontinuous coals; paucity of burrows and bioturbation; and presence of thin marine horizons combined with the facies architecture suggest a channelized depositional setting with some marine influence, indicative of fluvial or fluvial-dominated deltaic deposits.

Barden, M.J.

1989-03-01

126

Evaporite dissolution and pore fluid pressure as controls on diagenesis in complex fluvial HPHT reservoirs  

Microsoft Academic Search

Continental depositional systems influenced by salt movement are characterized by rapid lateral and vertical facies changes that are difficult to predict at reservoir scale. The Triassic Skagerrak Formation of the Central North Sea, UK is an excellent example of how the onset of Permian Zechstein salt movement strongly influenced the thickness, stratigraphy and facies distributions of this large fluvial system.

Binh Nguyen; Stuart Jones; Neil Goulty; Neil Grant; Jamie Middleton

2010-01-01

127

Fluvial rainbow trout contribute to the colonization of steelhead (Oncorhynchus mykiss) in a small stream  

USGS Publications Warehouse

Life history polymorphisms provide ecological and genetic diversity important to the long term persistence of species responding to stochastic environments. Oncorhynchus mykiss have complex and overlapping life history strategies that are also sympatric with hatchery populations. Passive integrated transponder (PIT) tags and parentage analysis were used to identify the life history, origin (hatchery or wild) and reproductive success of migratory rainbow/steelhead for two brood years after barriers were removed from a small stream. The fluvial rainbow trout provided a source of wild genotypes to the colonizing population boosting the number of successful spawners. Significantly more parr offspring were produced by anadromous parents than expected in brood year 2005, whereas significantly more parr offspring were produced by fluvial parents than expected in brood year 2006. Although hatchery steelhead were prevalent in the Methow Basin, they produced only 2 parr and no returning adults in Beaver Creek. On average, individual wild steelhead produced more parr offspring than the fluvial or hatchery groups. Yet, the offspring that returned as adult steelhead were from parents that produced few parr offspring, indicating that high production of parr offspring may not be related to greater returns of adult offspring. These data in combination with other studies of sympatric life histories of O. mykiss indicate that fluvial rainbow trout are important to the conservation and recovery of steelhead and should be included in the management and recovery efforts.

Weigel, Dana E.; Connolly, Patrick J.; Powell, Madison S.

2013-01-01

128

STABLE ISOTOPE ANALYSIS REVEALS FOOD WEB STRUCTURE AND WATERSHED IMPACTS ALONG THE FLUVIAL GRADIENT  

E-print Network

River Basin, Belize. Similar to previous studies in other regions, consumer species richness to values from forested reference sites. Assessment of primary consumer d15 N may be a feasible option, Ltd. key words: banana plantation; Belize; Bladen River; fish; fluvial gradient; Maya Mountain Marine

Hoeinghaus, David J.

129

Mechanosensory based orienting behaviors in fluvial and lacustrine populations of mottled sculpin (Cottus bairdi)  

Microsoft Academic Search

We compared prey-orienting and rheotactic behaviors in a fluvial (Coweeta Creek) and lacustrine (Lake Michigan) population of mottled sculpin. Blinded sculpin from both populations exhibited unconditioned, mechanosensory based rheotaxis to low velocity flows. Whereas Lake Michigan sculpin generally showed increasing levels of positive rheotaxis to increasing velocities, Coweeta Creek sculpin show varying levels of positive rheotaxis at low to intermediate

Sheryl Coombs; Gary D. Grossman

2006-01-01

130

Inverted fluvial features in the Aeolis-Zephyria Plana, western Medusae Fossae Formation, Mars: Evidence  

E-print Network

Inverted fluvial features in the Aeolis-Zephyria Plana, western Medusae Fossae Formation, Mars Science Experiment (HiRISE) stereo image pairs with individual data points from the Mars Orbiter Laser analysis suggests that multiple post-flow processes, including compaction of the deposits and tectonic

Tennessee, University of

131

Ice jam-caused fluvial gullies and scour holes on northern river flood plains  

Microsoft Academic Search

Two anomalous fluvial landforms, gullies and scour holes, eroded into flood plains bordering meandering and braiding river channels have not been previously reported. We observed these features along the Milk River in southern Alberta, Canada, and northern Montana, USA, which has a history of frequent (50% probability of recurrence) and high-magnitude (12% probability of recurrence greater than bankfull) ice jam

Derald G Smith; Cheryl M Pearce

2002-01-01

132

Equivalent dose distribution analysis of Holocene eolian and fluvial quartz sands from Central Oklahoma  

Microsoft Academic Search

Holocene quartz sands were collected from fluvial terrace deposits and eolian dune deposits adjacent to the North Canadian and Cimarron Rivers and their tributaries in Central Oklahoma. Single aliquot regenerative dose optically stimulated luminescence techniques were employed to generate equivalent dose (ED) distribution histograms for each sample. We hypothesize that the ED distributions are convolutions of the distribution arising from

Kenneth Lepper; Niels Agersnap Larsen; Stephen W. S McKeever

2000-01-01

133

Environmental changes in the central Po Plain (northern Italy) due to fluvial modifications and anthropogenic activities  

NASA Astrophysics Data System (ADS)

The fluvial environment of the central Po Plain, the largest plain in Italy, is discussed in this paper. Bounded by the mountain chains of the Alps and the Apennines, this plain is a link between the Mediterranean environment and the cultural and continental influences of both western and eastern Europe. In the past decades, economic development has been responsible for many changes in the fluvial environment of the area. This paper discusses the changes in fluvial dynamics that started from Late Pleistocene and Early Holocene due to distinct climatic changes. The discussion is based on geomorphological, pedological, and archaeological evidences and radiocarbon dating. In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the River Po. On the other hand, on the southern side of the Po Plain, no geomorphological evidence of similar discharge reduction has been found. Here, stratigraphic sections, together with archaeological remains buried under the fluvial deposits, show a reduction in the size of fluvial sediments after the 10th millennium BC. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuations in the rate of deposition, probably related to short and less intense climatic fluctuations. Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e., climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment. From the 1st to 3rd Century AD, land grants to war veterans caused almost complete deforestation, generalised soil erosion, and maximum progradation of the River Po delta. At present, land abandonment in the mountainous region has led to reafforestation. Artificial channel control in the mountain sector of the basins and in-channel gravel extraction (now illegal but very intense in the 1960s and 1970s) are causing erosion along the rivers and along large sectors of the Adriatic coast. These changes are comparable with those occurring in basins of other Mediterranean rivers.

Marchetti, Mauro

2002-05-01

134

Acceso a la plataforma Proquest utilizando PAPI / Shibboleth Inmaculada Ramos  

E-print Network

1 Acceso a la plataforma Proquest utilizando PAPI / Shibboleth Inmaculada Ramos Unidad de Recursos://bibliotecas.csic.es/papi-acceso-remoto-a-e- recursos Acceder a algún recurso contratado a través de Proquest (GeoRef, Index Islamicus, International Bibliography of the Social Sciences (IBSS), Linguistics and Language Behavior Abstracts (LLBA), ProQuest

135

Legacies of Glacio-fluvial Interactions in the Finger Lakes, Central New York  

NASA Astrophysics Data System (ADS)

The Finger Lakes region of central New York exhibits spectacular examples of the interplay between glacial and fluvial processes. The Finger Lakes themselves were carved by ice sheets and related subglacial hydrologic processes that enlarged, over-deepened, and reversed the drainage direction of pre-existing fluvial valleys. The region's famous gorges flank the glacial troughs and reflect ongoing fluvial adjustment to glacially driven base level variations. Modern tools of topographic analysis permit quantification of the imprint that glacial processes leave on fluvial form and process. Regionally, ice sheet erosion is maximized along the north end of the Seneca/Cayuga trough. Local relief ranges from ~100 m at the north end of Seneca and Cayuga lakes to 250-400 m on the southern ends of these lakes and on the smaller, flanking lakes (Keuka, Canandaigua, Skaneateles, Owasco). Concavity indices for lake-tributary stream profiles are predominantly in the range of -7 to 0, reflecting a convex initial form imposed by glacial processes, while normalized channel steepness (ksn) indices are generally under 40 (reference concavity of 0.45), reflecting the gentle gradients of the glacial uplands. Concavity index and ksn values are maximized (>0, and >75, respectively) along short segments at the downstream ends of the so-called interglacial or post-glacial gorge reaches, again maximized at the southern and peripheral parts of the Seneca/Cayuga trough. Finally, streams that cross former channel courses buried by subglacial debris typically have more numerous and/or more pronounced knickpoints and more concave long profile segments than streams that do not. In short, the legacy of glaciations from the regional to the reach scale appears to be driving patterns of fluvial response in the Finger Lakes.

Safran, E. B.; Fountain, A. G.

2011-12-01

136

Unincised fluvial and tide-dominated estuarine systems from the Mesoproterozoic Lower Tombador Formation, Chapada Diamantina basin, Brazil  

NASA Astrophysics Data System (ADS)

The Mesoproterozoic Lower Tombador Formation is formed of shallow braided fluvial, unconfined to poorly-channelized ephemeral sheetfloods, sand-rich floodplain, tide-dominated estuarine, and shallow marine sediments. Lowstand braided fluvial deposits are characterized by a high degree of channel amalgamation interbedded with ephemeral, intermediate sheetflood sandstones. Sand-rich floodplain sediments consist of intervals formed by distal sheetflood deposits interbedded with thin layers of eolian sandstones. Tide-dominated estuarine successions are formed of tide-influenced sand-bed braided fluvial, tidal channel, tidal sand flat and tidal bars. Shallow marine intervals are composed of heterolithic strata and tidal sand bars. Seismic scale cliffs photomosaics calibrated with vertical sections indicate high lateral continuity of sheet-like depositional geometry for fluvial-estuarine successions. These geometric characteristics associated with no evidence of incised-valley features nor significant fluvial scouring suggest that the Lower Tombador Formation registers deposition of unincised fluvial and tide-dominated systems. Such a scenario is a natural response of the interplay between sedimentation and fluctuations of relative sea level on the gentle margins of a sag basin. This case study indicates that fluvial-estuarine successions exhibit the same facies distributions, irrespective of being related to unincised or incised-valley systems. Moreover, this case study can serve as a starting point to better understand the patterns of sedimentation for Precambrian basins formed in similar tectonic settings.

Magalhes, A. J. C.; Scherer, C. M. S.; Raja Gabaglia, G. P.; Bllico, M. B.; Catuneanu, O.

2014-12-01

137

El tratamiento con cloro es un mtodo para desinfectar un pozo de agua. Se recomien-  

E-print Network

exceso de lluvia entran en el pozo. Si el agua subterránea constituye en sí la fuente de bacterias, elEl tratamiento con cloro es un método para desinfectar un pozo de agua. Se recomien- da cuando un sistema de agua está contam- inado con bacterias. La contaminación puede ocurrir en la instalación del

138

Fluvial sediment of the Mississippi River at St. Louis, Missouri  

USGS Publications Warehouse

An investigation of the fluvial sediment of the Mississippi River at St. Louis, Mo., was begun in 1948. Most data have been obtained only to determine the daily suspended-sediment discharge and the particle-size distribution of suspended sediment and bed material, but a few data have been obtained to study the flow resistance, the vertical distribution of sediment and velocity, and the bed-material discharge. The flow of the Mississippi River at St. Louis is made up of the flows from the Missouri River, which had an average flow of 79,860 cubic feet per second for 1897-1958 at Hermann, Mo., and from the upper Mississippi River, which had an average flow of 91,890 cubic feet per second for 1928-58 at Alton, Il. The Missouri River is partly controlled by reservoirs that had a total capacity of 90,300,000 acre-feet in 1956, and the upper Mississippi River is partly controlled by lakes and reservoirs that had a total capacity of 4,890,000 acre-feet in 1956. The flows of the Missouri and upper Mississippi Rivers have not become mixed at St. Louis; so the river has a lateral gradient of suspended-sediment concentration. The concentration near the west bank has been as much as 2,400 parts per million greater than the concentration near the east bank. Suspended-sediment discharges from April 1948 to September 1958 ranged from 4,250 to 7,010,000 tons per day and averaged 496,000 tons per day. Mean concentrations for water years decreased steadily from 1,690 parts per million in 1949 to 403 parts per million in 1956, but they increased to 756 parts per million in 1958. Effects of new reservoirs in the Missouri River basin on the concentration have been obscured by the close relation of concentration to streamflow. Measured suspended-sediment discharge through September 1958 averaged 47 percent clay, 38 percent silt, and 15 percent sand. Variations of particle size were due mainly to differences in the source areas of the sediment. Most of the bed material in the main flow was between 0.125 and 1.000 millimeter in diameter. The average of median diameters was related to the discharge for periods of 1 year and longer. Geometric quartile deviations of the bed material ranged from 1.1 to 2.5 and averaged 1.5. The mean elevation of the bed had a range of almost 10 feet and was related to the median diameter of bed material by the regression equation hb=363.0 - 7.8 d50 for which the standard error of estimate was 0.91 foot. The resistance to flow as measured by Manning's n ranged from 0.024 to 0.041 and was related to the discharge and mean velocity but not to the shear velocity. Normal dune height is 2-8 feet, and average dune length is about 250 feet. When the resistance to flow was low, much of the bed was fairly fiat; a few dunes were present, but they were much longer than the average. For a given discharge during individual rises in stage, the gage height was lower for increasing discharge than for decreasing discharge even though the bed elevation was higher. The changes in gage height were not caused by changes in energy gradient due to changing discharge, by channel storage between the gage and the measuring section, nor by return of overbank flow; but they were probably caused by a combination of changes in roughness due to changing bed configuration and of changes in turbulence constant due to changing sediment concentration. Turbulence constants (Von Karman's k) computed from velocity measurements at 5-10 points in the vertical and from routine velocity measurements at 2 points in the vertical averaged 0.35 and 0.33, respectively. The exponent z1 of the vertical distribution of concentration for different size ranges varied with about the 0.77 power of the fall velocity. Except for the difference between the theoretical variation and the actual variation of z1 with changing fall velocity, the theoretical equation for the vertical distribution of sediment concentration seems to apply reasonably well for the Miss

Jordan, Paul Robert

1965-01-01

139

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

NASA Astrophysics Data System (ADS)

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 Bdalen) 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 Bdalen (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 Bdalen drainage basin than in Erdalen. In both drainage basins fluvial bedload transport is smaller than fluvial suspended sediment transport. In Bdalen 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.

Beylich, A.; Laute, K.

2013-12-01

140

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

141

Temporal and spatial variability of tidal-fluvial dynamics in the St. Lawrence fluvial estuary: An application of nonstationary tidal harmonic analysis  

NASA Astrophysics Data System (ADS)

tides in upstream reaches of rivers is a challenge, because tides are highly nonlinear and nonstationary, and accurate short-time predictions of river flow are hard to obtain. In the St. Lawrence fluvial estuary, tide forecasts are produced using a one-dimensional model (ONE-D), forced downstream with harmonic constituents, and upstream with daily discharges using 30 day flow forecasts from Lake Ontario and the Ottawa River. Although this operational forecast system serves its purpose of predicting water levels, information about nonstationary tidal-fluvial processes that can be gained from it is limited, particularly the temporal changes in mean water level and tidal properties (i.e., constituent amplitudes and phases), which are function of river flow and ocean tidal range. In this paper, a harmonic model adapted to nonstationary tides, NS_TIDE, was applied to the St. Lawrence fluvial estuary, where the time-varying external forcing is directly built into the tidal basis functions. Model coefficients from 13 analysis stations were spatially interpolated to allow tide predictions at arbitrary locations as well as to provide insights into the spatiotemporal evolution of tides. Model hindcasts showed substantial improvements compared to classical harmonic analyses at upstream stations. The model was further validated by comparison with ONE-D predictions at a total of 32 stations. The slightly lower accuracy obtained with NS_TIDE is compensated by model simplicity, efficiency, and capacity to represent stage and tidal variations in a very compact way and thus represents a new means for understanding tidal rivers.

Matte, Pascal; Secretan, Yves; Morin, Jean

2014-09-01

142

Comparability and accuracy of fluvial-sediment data - A view from the U.S. Geological Survey  

USGS Publications Warehouse

The quality of historical fluvial-sediment data cannot be taken for granted, based on a review of upper Colorado River basin suspended-sediment discharges, and on an evaluation of the reliability of Total Suspended Solids (TSS) data. Additionally, the quality of future fluvial-sediment data are not assured. Sediment-surrogate technologies, including those that operate on acoustic, laser, bulk optic, digital optic, or pressure differential principles, are being used with increasing frequency to measure in-stream and (or) laboratory fluvial-sediment characteristics. Data from sediment-surrogate technologies may yield results that differ significantly from those obtained by traditional methods for the same sedimentary conditions. Development of national sediment data-quality criteria and rigorous comparisons of data derived from sediment-surrogate technologies to those obtained by traditional techniques will minimize the potential for future fluvial-sediment data-quality concerns.

Gray, J.R.; Glysson, G.D.; Mueller, D.S.

2002-01-01

143

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)

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

Langhammer, Jakub; Mi?ijovsk, Jakub; Hartvich, Filip; Kaiglov, Jana

2014-05-01

144

Regional variations in the fluvial Upper Devonian and Lower Mississippian(?) Kanayut Conglomerate, Brooks Range, Alaska  

USGS Publications Warehouse

The wholly allochthonous Upper Devonian and Lower Mississippian(?) Kanayut Conglomerate is one of the most extensive fluvial deposits in North America. It crops out for 950 km along the crest of the Brooks Range in a series of thrust plates and is as thick as 2615 m. The Kanayut forms the fluvial part of a large, coarse-grained delta. The lower part of the Kanayut (the Ear Peak Member) overlies marginal-marine and prodelta turbidite deposits and consists of fining-upward meandering-stream-channel cycles of conglomerate and sandstone within black to maroon floodplain shale deposits. The middle part of the Kanayut (the Shainin Lake Member) lacks shale and consists of fining-upward couplets of channelized conglomerate and parallel- to cross-stratified sandstone interpreted as braidplain deposits. These deposits contain the largest clasts (23 cm) and were deposited during maximum progradation of the fluvial sequence. The upper part of the Kanayut (the Stuver Member), which consists of fining-upward meandering stream cycles similar to those of the lower part, grades upward into overlying Lower Mississippian tidal and marginal-marine deposits. Paleocurrent data and distribution of largest clasts indicate that the Kanayut was deposited by southwest-flowing streams fed by at least two major trunk streams that drained a mountainous region to the north and east. Comparison of stratigraphic and sedimentologic data collected at three selected locations representative of proximal, intermediate and distal parts of the Kanayut basin reveal regional variations in its fluvial character. These include a decrease in total thickness of fluvial strata, an increase in total thickness of associated marine sandstone, the pinch-out of the coarse-grained middle part of the Kanayut and decreases in the conglomerate/sandstone and sandstone/shale ratios from proximal to distal areas of the basin. The coarse-grained parts of the fluvial cycles decrease in thickness and lateral extent from proximal to distal areas of the basin. In more distal areas of sedimentation, the middle parts of some fluvial cycles consist of calcareous and bioturbated marine sandstone. Although thinner than in more proximal areas, the associated fine-grained upper parts of some cycles also contain marine features and suggest that these strata represent the deposits of interdistributary bays. These features are interpreted to indicate that the proximal deposits of the Kanayut Conglomerate were deposited by large, stable fine-grained meandering rivers (the Ear Peak and Stuver Members) and gravelly braided rivers (Shainin Lake Member) on the upper delta plain of the Kanayut delta. Sedimentation in more distal locations, interpreted to represent lower delta plain deposits, was by smaller distributary rivers with characteristics of both braided and meandering streams. Near their interface with marginal marine deposits the fluvial deposits were locally strongly influenced by tidal or estuarine conditions. ?? 1984.

Moore, T.E.; Nilsen, T.H.

1984-01-01

145

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

Microsoft Academic Search

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

Thomas C. Chidsey Jr.; T. C. Jr

1995-01-01

146

Fluvial deposits of Yellowstone tephras: Implications for late Cenozoic history of the Bighorn basin area, Wyoming and Montana  

USGS Publications Warehouse

Several deposits of tephra derived from eruptions in Yellowstone National Park occur in the northern Bighorn basin area of Wyoming and Montana. These tephra deposits are mixed and interbedded with fluvial gravel and sand deposited by several different rivers. The fluvial tephra deposits are used to calculate stream incision rates, to provide insight into drainage histories and Quaternary tectonics, to infer the timing of alluvial erosion-deposition cycles, and to calibrate rates of soil development. ?? 1992.

Reheis, M.C.

1992-01-01

147

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

Microsoft Academic Search

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.

Detlef Mader

1985-01-01

148

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

Microsoft Academic Search

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.

Detlef Mader

149

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

Microsoft Academic Search

Antioxidant enzymes are involved in important processes of cell detoxification during oxidative stress and have, therefore,\\u000a been used as biomarkers in algae. Nevertheless, their limited use in fluvial biofilms may be due to the complexity of such\\u000a communities. Here, a comparison between different extraction methods was performed to obtain a reliable method for catalase\\u000a extraction from fluvial biofilms. Homogenization followed

Chlo Bonnineau; Berta Bonet; Natlia Corcoll; Helena Guasch

2011-01-01

150

Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir, Class I  

SciTech Connect

This report demonstrates the effectiveness of the CO2 miscible process in Fluvial Dominated Deltaic reservoirs. It also evaluated the use of horizontal CO2 injection wells to improve the overall sweep efficiency. A database of FDD reservoirs for the gulf coast region was developed by LSU, using a screening model developed by Texaco Research Center in Houston. The results of the information gained in this project is disseminated throughout the oil industry via a series of SPE papers and industry open forums.

Bou-Mikael, Sami

2002-02-05

151

Identification of remaining oil resource potential in the Frio Fluvial/Deltaic Sandstone play, South Texas  

SciTech Connect

The Frio Fluvial/Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas has produced nearly 1 billion stock tank barrels (BSTB) of oil, yet still contains about 1.2 BSTB of unrecovered mobile oil and an even greater amount of residual oil resources (1.5 BSTB). More than half of the reservoirs in this depositionally complex play have been abandoned, and large volumes of oil may remain unproduced. Interwell-scale geological facies models of Frio fluvial/deltaic reservoirs will be combined with engineering assessments and geophysical evaluations in order to characterize Frio fluvial/deltaic reservoir architecture, flow unit boundaries, and the controls that these characteristics exert on the location and volume of unrecovered mobile and residual oil. Reservoir attribute data were statistically analyzed from oil and gas fields throughout the geographic area covered by the Frio Fluvial/Deltaic Sandstone oil play. General reservoir attributes analyzed in detail included porosity, initial water saturation, residual oil saturation, net pay, reservoir area, and fluid characteristics. Statistical analysis of variance demonstrated no difference between oil reservoir attributes and gas reservoir attributes. Probability functions that describe attribute frequency distributions were determined for use in risk adjusting resource calculations. The oil play was found to contain significant volumes of remaining oil. The volumetric probability distribution between 5- and 95-percent probability for original oil in place ranges from 3.8 to 5.6 BSTB, original mobile oil in place ranges from 2.5 to 3.6 BSTB, and residual oil ranges from 1.5 to 2.3 BSTB. The untapped oil resource may be 10 percent of the original oil in place, or 380 million stock tank barrels.

Holtz, M.H.; McRae, L.E.; Tyler, N.

1994-05-01

152

The Holocene landscape development of the Gareja region in eastern Georgia - a fluvial approach  

NASA Astrophysics Data System (ADS)

The semi-arid Gareja region in the Iori Highland in the southeastern part of the Republic of Georgia is characterized by an annual precipitation < 500 mm and shows an open steppic landscape today. As is known from historical sources, the landscape showed the same character already during the 6th century AD when the Gareja monastery located in the center of the region was founded by Assyrian monks. However, archaeological research carried out during the Soviet Period showed that there were dozens of settlements of bronze and iron age in this region almost devoid of water resources today, hinting to some sources of fresh water allowing people to live there during those periods. Furthermore, former archaeobotanical studies assume that the region was covered by forests instead of steppes during the past, although there is no final proof yet. The goal of this study is to shed light on the development of the palaeo-landscape during the prehistoric period and thus to address some of the issues described above. To do so, our work is based on the network of episodic streams that cross the region, running from the Iori mountains towards the Mtkvari (Kura) river as the main gaining stream of the region. Using rain water flow direction modeling in GIS we determined the main fluvial courses according to their. This pattern was compared with that of prehistoric settlements known from archaeologic studies, in order to get information about the possible perennial character of some rivers during the past. Furthermore, we did first investigations of outcrops with fluvial sediments found along some of such fluvial courses: Based on stratigraphic observations, pedologic investigations of potential palaeosols as indicators of landscape stability as well as on first numerical datings, we started to unravel the fluvial pattern of that region.

Sukhishvili, Lasha; Elashvili, Mikheil; Janelidze, Zurab; Kikvadze, Bagrat; Navrozashvili, Levan; von Suchodoletz, Hans

2013-04-01

153

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

Microsoft Academic Search

PurposeThis 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

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

2010-01-01

154

Fluvial obstacle marks as complex geomorphic systems: a comparison between physically modelled and natural forms  

NASA Astrophysics Data System (ADS)

Fluvial obstacle marks are bedforms that develop if flow is separated by an immobile obstacle at the stream bed. Due to local acceleration and deceleration of the flow, areas of potential erosion and deposition arise in the obstacle surrounding. This results in forms that commonly consist of a scour hole reaching from the upstream part to the sides of an obstacle and an adjacent depositional ridge. Natural fluvial obstacle marks develop around pebbles, boulders, woody debris and plants. Individual forms of obstacle marks result from specific current patterns in the obstacle surrounding, which in turn are dependent on a variety of independent parameters like obstacle shape, -inclination, -alignment, -geometry, -porosity, -surface roughness and -flexibility as well as on sediment grading, bed-resistance, flow velocity, flow depth and steadiness of flow. Reciprocal interactions of these parameters make natural obstacle marks noteworthy examples of complex geomorphic systems. In contrast, experimentally simulated obstacle marks in laboratory flumes can be regarded as complexity-reduced geomorphic systems and are characterised by diverging morphological features compared to natural obstacle marks. In spite of these emergent divergences flume experiments are still inevitable to identify principle formative processes. Also experimental simulations are necessary to develop physically-based explanatory approaches that can predict significant morphometric features (like maximum depth of scour, eroded/deposited material) of fluvial obstacle marks. Within the scope of this work examples of natural fluvial obstacle marks are compared with obstacle marks simulated experimentally in a laboratory flume. In spite of morphological differences it can be deduced that a horseshoe-vortex system is the main agent that drives formative processes in the obstacle surrounding. The input of kinetic energy into this vortex system can be well described by determining the obstacle Reynolds number.

Euler, T.

2009-04-01

155

The resazurin-resorufin tracer for quantifying respiration and surface water - groundwater interactions in fluvial ecosystems  

NASA Astrophysics Data System (ADS)

Resazurin is a metabolically active compound that undergoes an irreversible reaction to resorufin in the presence of aerobic respiration. The amount of the reaction is linearly proportional to respiration. Consequently, the compound is useful as an tracer of respiration and groundwater - surface water interactions in fluvial ecosystems. We provide a summary of the development and use of resazurin in these contexts, and illustrate with several field examples.

Haggerty, R.; Gonzalez-Pinzon, R.; Marti, E.; Argerich, A.; Myrold, D.; Argerich, A.

2012-12-01

156

Dating Fluvial Terraces by 230Th\\/U on Pedogenic Carbonate, Wind River Basin, Wyoming  

Microsoft Academic Search

Reliable and precise ages of Quaternary pedogenic carbonate can be obtained with 230Th\\/U dating by TIMS applied to large suites of carefully selected small samples. Datable carbonate can form within a few thousand years of surface stabilization allowing ages of Quaternary deposits and surfaces to be closely estimated. We have dated pedogenic carbonate from glacio-fluvial terraces of the Wind River

W. D. Sharp; K. R. Ludwig; O. A. Chadwick; R. Amundson; L. L. Glaser

2001-01-01

157

Dating fluvial terraces by 230Th\\/U on pedogenic carbonate, Wind River Basin, Wyoming  

Microsoft Academic Search

Reliable and precise ages of Quaternary pedogenic carbonate can be obtained with 230Th\\/U dating by thermal ionization mass spectrometry applied to carefully selected milligram-size samples. Datable carbonate can form within a few thousand years of surface stabilization allowing ages of Quaternary deposits and surfaces to be closely estimated. Pedogenic carbonate clast-rinds from gravels of glacio-fluvial terraces in the Wind River

Warren D Sharp; Kenneth R Ludwig; Oliver A Chadwick; Ronald Amundson; Laura L Glaser

2003-01-01

158

Fluvial suspended sediment dynamics: Implications for particulate organic carbon transport modeling  

Microsoft Academic Search

The effect of fluvial suspended sediment aggregation on the hydrodynamic transport properties of particulate organic carbon (POC) was investigated using a combination of field measurement and numerical modeling. Field-based settling tube experiments were conducted to obtain particle settling velocity frequency distributions of a 4-km-long section of a lake outlet river at two distinct discharge levels (6.8 and 29.7 m3 s?1).

Heinz Bungartz; Angela Krger; Christof Engelhardt

2006-01-01

159

Aplicaciones de Arc GISAplicaciones de Arc GIS en Recursos de Aguaen Recursos de Agua  

E-print Network

Lluvia, Caudal, Calidad dela isla. Red de monitoreo de Lluvia, Caudal, Calidad de Agua, acuíferos, etcAplicaciones de Arc GISAplicaciones de Arc GIS en Recursos de Aguaen Recursos de Agua Alejandra predominantemente eventos de alta intensidad de lluvia.intensidad de lluvia. En promedio un huracán durante los

Gilbes, Fernando

160

El uso del agua en Njar: Implicaciones ambientales del modelo actual de gestin  

Microsoft Academic Search

RESUMEN Njar, municipio del SE almeriense, experimenta, hoy por hoy, una coyuntura de escasez del agua sin precedentes. El modelo de gestin actual, basado en la explotacin de las aguas subterrneas, y protagonizado por una agricultura intensiva en crecimiento y una incipiente actividad turstica, ha conducido al progresivo agotamiento de los acuferos locales. En respuesta a tal coyuntura, se implementan

Francisco Javier Toro Snchez

2008-01-01

161

Fingerprinting the sources of fluvial sediment using fallout and in-situ radionuclides in forested watershed in Japan  

NASA Astrophysics Data System (ADS)

To study the fluvial sediment sources in forested watershed in Shikoku island, Japan, the concentration of Cs-137 and Pb-210ex, U and Th decay series radaionuclides were analyzed. The soil sampling was conducted in hillslopes in various locations such as landslide scar, surface erosion in unmanaged Hinoki (Chamaecyparis obtusa) plantation, and detailed sampling in the channel deposit was also conducted in several tributaries. The activities of Cs-137, Pb-210ex, Bi-214 and Tl-208 of soils and fluvial sediments were determined by gammaspectroscopy. We also analyzed landuse of the watershed and forest logging area and landslide area were measured by air photo interpretation. The study area is Shimanto river basin, located 700 km southwest of Tokyo. The 2270 km2 area watershed ranges in elevation from 0 m to 1485 m above sea level. Low concentration of Cs-137 and Pb-210ex in fine sediments and surface soil at landslide scar suggest that fluvial sediments are derived from surface soil of the landslide scars or from channel walls. The concentrations of Cs-137 and Pb-210ex of fluvial sediment are found to be decrease as the landslide area increases. The data of U and Th decay series radionuclides, Bi-214 and Tl-208, indicate that the sources of fluvial sediment are adjacent to the sampling sites. The results suggest that landslide scar and adjacent to the channel are dominant sources of fluvial sediment in this watershed.

Kato, H.; Onda, Y.; Hiramatsu, S.; Seki, R.

2003-12-01

162

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

USGS Publications Warehouse

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.

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

2007-01-01

163

Fluvial response to late Quaternary climatic fluctuations, central Kobuk Valley, northwestern Alaska  

SciTech Connect

Much of northwestern Alaska remained unglaciated during the Pleistocene and thus offers a favorable setting for examining long-term records of high-latitude geological and biological change. Epiguruk, a large cut bank 3.5 km long and up to 36 m high on the Kobuk River south of the Brooks Range in eastern Beringia, exposes complex sedimentary successions representing cycles of upper quaternary alluviation and eolian sedimentation, downcutting, and soil formation. A rich record of plants and mammals is also preserved in the section. Deposits of fluvial channels and flood plains, eolian dunes, sand sheets, loess, and ponds, as well as organic soils (Histosols) are represented. Parallel-bedded fine sand and coarse silt couplets that commonly contain root structures, ripple cross-lamination, silt drapes are flood-plain sediments apparently deposited at the interface of fluvial and eolian environments. Multiple fluvial-to-eolian depositional sequences were caused by influx of eolian sediment to the river from intermittently active dune fields south of the Kobuk River. Alluviation in the Kobuk Valley was coeval with glaciation in the Brooks Range, whereas downcutting occurred during interstadials when dune stabilization limited sediment supply. The depositional model developed at Epiguruk may be useful in interpreting some of the widespread subhorizontally stratified late-glacial deposits of Europe and North America.

Ashley, G.M. (Rutgers Univ., New Brunswick, NJ (United States). Dept. of Geological Sciences); Hamilton, T.D. (U.S. Geological Survey, Anchorage, AK (United States))

1993-09-01

164

Fluvial dynamics of the lower Guadalete River in W-Andaluca (Spain) and decisive driving forces  

NASA Astrophysics Data System (ADS)

This study aims to work out a solid stratigraphy for the Guadalete River in W-Andaluca with focus on late Pleistocene and Holocene fluvial dynamics. We studied 14 profile exposures and 13 percussion drillings by using geomorphologic, sedimentologic and pedogenetic approaches. Supported by ample physical and chemical soil analyses and dating of 34 radiocarbon samples, we were able to reconstruct floodplain development over the last 14 ka. The valley of the lower Guadalete River shows a fluvial architecture that is complex and inconsistent along specific river sections. According to stratigraphic findings, the lower reach of the Guadalete River can be divided into two sedimentary areas. These are characterized by a highly dynamic alternation of sedimentation and erosion, with Holocene terrace formation in the upper downstream section and more calm conditions with sediment preservation and the built-up of continuous sequences in the lower one. Stratigraphic records in combination with a disturbed longitudinal profile revealed that fluvial dynamics responded to various driving forces in late Pleistocene and Holocene times. Sea-level changes have been a determining factor on river dynamics, notably during the late Pleistocene and until the early Holocene, when phases of sea-level fall resulted in strong river incision and clearing-out of floodplain sediments. In the course of a rapid sea-level rise until the early to mid-Holocene, other parameters started to play a determining role, as fluvial dynamics became more and more the expression of environmental conditions in terms of stability and instability of the landscape. As the study area has to be characterized as tectonically very active, the magnitude of fluvial processes, such as river incision was furthermore influenced by small-scale tectonic uplift or subsidence. Periods of floodplain sedimentation (before 9.2, after 8.0, at 4.6 to 4.3, at 2.0, 0.9 and 0.4 ka cal BP) are reflective for unstable landscape conditions, often related to aridification. For a comprehensive consideration of triggers of floodplain sedimentation, we have likewise to take human behavior into account. It is not possible, however, to clearly differentiate between the impact of climate and humans on geomorphologic activity, but it seems reasonable that anthropogenic exploitation and cultivation activities contributed to raise the environmental pressure exerted by increased aridity.

Wolf, Daniel; Faust, Dominik

2013-04-01

165

A fluvial and pluvial probabilistic flood hazard analysis for Can Tho city, Vietnam  

NASA Astrophysics Data System (ADS)

Can Tho city is the largest city and the economic heart of the Mekong Delta, Vietnam. Due to its economic importance and envisaged development goals the city grew rapidly in population size and extend over the last two decades. Large parts of the city are located in flood prone areas, and also the central parts of the city recently experienced an increasing number of flood events, both of fluvial and pluvial nature. As the economic power and asset values are constantly increasing, this poses a considerable risk for the city. The the aim of this study is to perform a flood hazard analysis considering both fluvial and pluvial floods and to derive probabilistic flood hazard maps. This requires in a first step an understanding of the typical flood mechanisms. Fluvial floods are triggered by a coincidence of high water levels during the annual flood period in the Mekong Delta with high tidal levels, which cause in combination short term inundations in Can Tho. Pluvial floods are triggered by typical tropical convective rain storms during the monsoon season. These two flood pathways are essentially independent in its sources and can thus be treated in the hazard analysis accordingly. For the fluvial hazard analysis we propose a bivariate frequency analysis of the Mekong flood characteristics, the annual maximum flood discharge Q and the annual flood volume V at the upper boundary of the Mekong Delta, the gauging station Kratie. This defines probabilities of exceedance of different Q-V pairs, which are transferred into synthetic flood hydrographs. The synthetic hydrographs are routed through a quasi-2D hydrodynamic model of the entire Mekong Delta in order to provide boundary conditions for a detailed hazard mapping of Can Tho. This downscaling step is necessary, because the huge complexity of the river and channel network does not allow for a proper definition of boundary conditions for Can Tho city by gauge data alone. In addition the available gauge data around Can Tho are too short for a meaningful frequency analysis. The detailed hazard mapping is performed by a 2D hydrodynamic model for Can Tho city. As the scenarios are derived in a Monte-Carlo framework, the final flood hazard maps are probabilistic, i.e. show the median flood hazard along with uncertainty estimates for each defined level of probabilities of exceedance. For the pluvial flood hazard a frequency analysis of the hourly rain gauge data of Can Tho is performed implementing a peak-over-threshold procedure. Based on this frequency analysis synthetic rains storms are generated in a Monte-Carlo framework for the same probabilities of exceedance as in the fluvial flood hazard analysis. Probabilistic flood hazard maps were then generated with the same 2D hydrodynamic model for the city. In a last step the fluvial and pluvial scenarios are combined assuming independence of the events. These scenarios were also transferred into hazard maps by the 2D hydrodynamic model finally yielding combined fluvial-pluvial probabilistic flood hazard maps for Can Tho. The derived set of maps may be used for an improved city planning or a flood risk analysis.

Apel, Heiko; Martinez, Oriol; Thi Chinh, Do; Viet Dung, Nguyen

2014-05-01

166

Late-Stage Fluvial Erosion in a Changing Climate on Early Mars  

NASA Astrophysics Data System (ADS)

The decline of heavy bombardment in the solar system coincided with incision of many branching fluvial valleys in the martian highlands. However, these valley networks are underdeveloped relative to typical terrestrial networks, suggesting that valley incision was geologically brief or slow on Mars. Most previous studies have attributed the end of martian fluvial erosion to a monotonic decline of the atmosphere and climate around the Noachian/Hesperian transition. Identification of fluvial valleys on some younger surfaces, including Hesperian volcanoes, and the occurrence of morphologically pristine and degraded reaches in the same valley networks challenged the simplicity of this model. More recently, fluvial valleys and deposits have been recognized on a variety of Hesperian surfaces, including the plateau around Valles Marineris, certain impact craters, and the crustal dichotomy boundary scarp. The extent to which this late-stage erosion represents localized event floods or more widely distributed precipitation and runoff remains to be determined. To evaluate whether Hesperian resurfacing processes were concurrent with (and may have caused) late-stage fluvial erosion, we are identifying any geologically rare or long-lived events that occurred between significant resurfacing events and fluvial erosion of those surfaces. In a variety of locations, we have identified small primary craters that formed between local resurfacing and fluvial dissection of those surfaces, suggesting a gap in time between resurfacing and dissection. These small, otherwise fresh craters have rims or ejecta that were incised by late-stage flows. In other cases, thick stratified deposits accumulated on Hesperian surfaces, and those deposits were later dissected by running water. We also found that highland intercrater plains generally have Early to mid-Hesperian crater populations at diameters less than about 4 km. All smaller primary and secondary craters from the Noachian Period were eradicated. These observations suggest the following geomorphic history. 1) Crater degradation and intercrater resurfacing extended into the Early Hesperian Epoch, but perhaps at a declining rate relative to the Noachian Period. 2) Most of the relict valleys formed as crater degradation declined and intercrater geomorphic surfaces began to stabilize, late in the Noachian or early in the Hesperian Period. 3) Impact cratering, volcanism, tectonism, and wind continued to modify the martian surface during the Hesperian Period. Older valley networks experienced some wall retreat and infilling, forming the classic flat-floored morphology. 4) In one or more intervals during the Late Hesperian or Early Amazonian Epochs, many older valleys reactivated, and some new ones formed on Hesperian surfaces. Late-stage erosion was most effective on steep, high-relief slopes, including Late Noachian and Hesperian crater walls, as well as tectonic scarps. In ongoing work, identifying clear stratigraphic relationships between older valleys, interposed geologic features, and younger valleys is key to determining the number and relative ages of erosional events in the martian highlands.

Irwin, R. P.; Matsubara, Y.

2013-12-01

167

Fluvial sedimentation on a quivering craton: Influence of slight crustal movements on fluvial processes, upper Jurassic Morrison formation, western Colorado plateau  

USGS Publications Warehouse

One of the most important challenges facing the fluvial sedimentologist is identification of processes outside the stream channel that influence deposition of fluvial sediments. Detailed studies in the lower sequence of the Salt Wash Member (Morrison Formation, Upper Jurassic) demonstrate that crustal deformation at the site of deposition may considerably influence braided-stream processes. Late Jurassic crustal movements in the western part of the Colorado Plateau are interpreted largely from thickness variations and facies distribution, but other features such as vertical repetition of facies, coincidence with at least parts of present-day folds, and the geographic distribution of bedding parameters measured in the fluvial deposits, are also used as corroborating evidence of syndepositional tectonism. These features indicate that several of the large uplifts and basins in the region as well as some of the smaller folds within them were actively moving during deposition of the lower sequence. Tectonic activity altered the stream gradients, which in turn governed sinuosity, flow regime, energy levels, and sediment distribution. Cross-bedding studies indicate that reduced gradients within downwarped areas led to slight increases in sinuosity of the braided-stream channels and of the small sub-channels within them. The lowered gradients apparently resulted in a decrease in the depth of the channels and allowed the streams to flood more readily, producing abundant upper-flow regime horizontal laminations in the channel deposits. In addition, greater quantities of sediment containing higher proportions of sand were deposited in downwarped areas than in positive localities. The inability of the streams to transport bed load through downwarped areas indicates loss of stream energy. However, an increase in the quantity of upper-flow regime horizontal laminations in the same downwarped areas suggests that an increase in flow regime is not necessarily accompanied by an increase in energy levels, at least in regions of slight tectonic activity where the local configuration of the stream channels may change appreciably. Strata presently dip less than 2?? throughout most of the region, and this relatively small amount of deformation reflects the combined effects of Late Jurassic, Cretaceous and Tertiary tectonism. This demonstrates that the amount of structural deformation at the site of deposition may appear to be insignificant, yet it can cause appreciable changes in the nature of braided-stream deposits. ?? 1984.

Peterson, F.

1984-01-01

168

Sequence stratigraphic architecture of a differentially subsiding bay to fluvial basin: the Eocene Ishikari Group, Ishikari Coal Field, Hokkaido, Japan  

NASA Astrophysics Data System (ADS)

The Eocene Ishikari Group, deposited in a bay to fluvial basin in central Hokkaido, Japan, provides important information on fluvial sequence stratigraphy in a differentially subsiding ocean-connected setting. The Ishikari Group consists of four million-year-order depositional sequences (Isk-1, Isk-2, Isk-3 and Isk-4), composed mainly of meandering/braided fluvial systems. Each depositional sequence contains marine or lacustrine incursion beds, which show lake or bay to bay-margin tidal facies, at maximum flooding surface horizons. This indicates that marine or lacustrine incursion into fluvial environments took place when the increase rate of accommodation space due to relative sea-level rise exceeded the rate of accumulation. Fluvial channel stacking density varies in response to stratigraphic position within a depositional sequence, namely, high channel density in the lower part of the transgressive interval (Trs: LST to TST) and the upper part of the regressive interval (Rgr: HST), and low channel density in upper Trs and lower Rgr. Multistory channels tend to be developed in lower Trs, whereas single-story channels predominate in upper Trs and Rgr. These patterns in the distribution of fluvial channels resulted from changes in accommodation space in response to relative sea-level changes. Sequence boundaries are recognized at fluvial incision surfaces at the base of Trs, but the development of incised valleys is minor because of the relatively high subsidence rate, which obscured the effect of relative sea-level fall. Syndepositional differential subsidence within the paleo-Ishikari basin resulted in selective development of relatively downstream depositional systems in the more rapidly subsiding area. High-frequency depositional cycles are also prominently developed in the subsiding area where sedimentation rate was sufficiently high to record high-frequency relative sea-level cycles or autocycles of deposition.

Takano, Osamu; Waseda, Amane

2003-08-01

169

Biosorption behavior and mechanism of cesium-137 on Rhodosporidium fluviale strain UA2 isolated from cesium solution.  

PubMed

In order to identify a more efficient biosorbent for (137)Cs, we have investigated the biosorption behavior and mechanism of (137)Cs on Rhodosporidium fluviale (R. fluviale) strain UA2, one of the dominant species of a fungal group isolated from a stable cesium solution. We observed that the biosorption of (137)Cs on R.fluviale strain UA2 was a fast and pH-dependent process in the solution composed of R.fluviale strain UA2 (5g/L) and cesium (1mg/L). While a Langmuir isotherm equation indicated that the biosorption of (137)Cs was a monolayer adsorption, the biosorption behavior implied that R.fluviale strain UA2 adsorbed cesium ions by electrostatic attraction. The TEM analysis revealed that cesium ions were absorbed into the cytoplasm of R.fluviale strain UA2 across the cell membrane, not merely fixed on the cell surface, which implied that a mechanism of metal uptake contributed largely to the cesium biosorption process. Moreover, PIXE and EPBS analyses showed that ion-exchange was another biosorption mechanism for the cell biosorption of (137)Cs, in which the decreased potassium ions were replaced by cesium ions. All the above results implied that the biosorption of (137)Cs on R.fluviale strain UA2 involved a two-step process. The first step is passive biosorption that cesium ions are adsorbed to cells surface by electrostatic attraction; after that, the second step is active biosorption that cesium ions penetrate the cell membrane and accumulate in the cytoplasm. PMID:24631916

Lan, Tu; Feng, Yue; Liao, Jiali; Li, Xiaolong; Ding, Congcong; Zhang, Dong; Yang, Jijun; Zeng, Junhui; Yang, Yuanyou; Tang, Jun; Liu, Ning

2014-08-01

170

Effects of chronic copper exposure on fluvial systems: linking structural and physiological changes of fluvial biofilms with the in-stream copper retention.  

PubMed

Long-term metal exposure is known to be responsible for a large variety of structural and functional changes in periphyton communities which allow these communities to adapt to metal-polluted conditions. This study aimed to link the changes that chronic copper (Cu) exposure causes on the structure and physiology of fluvial biofilms with the efficiency of the river systems in retaining phosphate and Cu. The effects of a chronic Cu exposure on the structure, physiology and induction of Cu tolerance of the community were evaluated by comparing this community with a non-exposed one. Results showed that periphyton chronically exposed to Cu had lower algal biomass, higher proportion of green algae, lower proportion of brown algae, and higher EPS content per unit of biomass than the un-exposed community. In addition, the chronically-exposed community showed a Cu content (both total and intracellular Cu content) ten times higher than the un-exposed community. While in-stream phosphate retention was not markedly influenced by chronic Cu exposure; Cu retention was clearly reduced, as was shown by a reduction in Cu retention efficiency (Cu-S(w)) and demand (Cu-Vf). The chronically-exposed periphyton, in spite of having high intracellular Cu concentration, showed similar photosynthetic efficiency than the un-exposed community and showed a higher Cu tolerance. It indicated that this community was acclimatized to Cu exposure and that this acclimatization was probably linked to the ability to detoxify and immobilize metals. These observations suggest that the fate of Cu in fluvial ecosystems will be influenced by the exposure history of the system. The results from this study indicate that metals will travel longer distances in metal-polluted streams compared to pristine systems having effects on water quality farther downstream. PMID:19646733

Serra, A; Guasch, H

2009-09-15

171

La Transpiración - Movimiento del Agua a Través de las Plantas  

NSDL National Science Digital Library

La transpiración es la pérdida de agua en forma de vapor por las plantas. El agua es absorbida del suelo por las raíces y transportada en forma líquida por el xilema hacia las hojas. En las hojas, unos pequeos poros permiten que el agua (H2O) escape a la atmósfera en forma de vapor, al tiempo que se permite la entrada de bióxido de carbono (CO2) para la fotosíntesis. De toda el agua absorbida por las plantas, menos del 5% es retenida y utilizada para crecimiento y almacenamiento. En esta lección se explicará porque las plantas pierden tanta agua, la ruta que ésta sigue dentro de la planta, como pudieran las plantas controlar la pérdida excesiva de agua y como las condiciones ambientales influyen en la pérdida de agua por las plantas.

172

The development of fluvial stochastic modelling in the Norwegian oil industry: A historical review, subsurface implementation and future directions  

NASA Astrophysics Data System (ADS)

Fluvial sandstones are an important reservoir type for the petroleum industry. In the late 1970's and early 1980's, large hydrocarbon discoveries in the Norwegian North Sea in fluvial strata prompted the need for generating geologically meaningful, stochastic, object-based models of fluvial deposits. The aim of this focus was to allow the geologist to provide the reservoir engineers with a more realistic representation of permeability contrasts within channelised, fluvial deposits by being able to use appropriate measurements from outcrop analogues as direct input data into the modelling software. This initiative resulted in the development of a suite of geologically driven, stochastic modelling algorithms supported by an extensive fieldwork program aimed at collecting stratigraphic and quantitative data from ancient outcrop analogues to support enhanced reservoir characterisation and geological modelling. Today, these reservoirs are still important hydrocarbon producing fields with accurate reservoir description and 3D modelling capabilities playing a vital role in targeting remaining oil, especially now that many of the fields on the Norwegian continental shelf are past peak production and are in a decline phase. As both computing capabilities and quantitative outcrop analogue studies have increased the understanding of, and the ability to model fluvial reservoirs, so have stochastic modelling techniques continued to provide the most suitable and robust means of building geologically realistic 3D reservoir models that incorporate increased geological understanding and heterogeneity complexity. In the recent past, a multitude of data, such as seismic and production data have been used to condition the stochastic algorithms. This review paper aims to outline the role of stochastic algorithms in building geologically-realistic, 3D fluvial reservoir models and highlight the success of these developments with case studies from both producing fields and ancient outcrop analogue studies. Finally, the paper will allude to possible improvements in stochastic fluvial modelling and future directions in the modelling of fluvial petroleum reservoirs. These include the use of physical or process-based models, high-resolution near wellbore models, and multi-point statistics, that allow for more realistic representations of heterogeneities of fluvial deposits at a variety of scales and by a variety of methods.

Keogh, Kevin Joseph; Martinius, Allard Willem; Osland, Rune

2007-11-01

173

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

SciTech Connect

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.

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

1993-04-01

174

Late Quaternary changes in flow-regime on the Gwydir distributive fluvial system, southeastern Australia  

NASA Astrophysics Data System (ADS)

Ages for large palaeochannels of the Gwydir distributive fluvial system (DFS) in northern New South Wales, Australia have been determined using single grain optically stimulated luminescence. Two palaeochannel systems have been found to dominate; the here named Coocalla (43-34 ka) and Kamilaroi (19-16 ka) which have inferred palaeodischarges 25-100 times the bankfull discharges of nearby channels of the contemporary Gwydir system, which appears to have been established during the Mid-Holocene. This scale differential is very much larger than that reported for other catchments in southeastern Australia, and reflects both a decline in catchment runoff through the Last Glacial cycle and the adoption of a distributary pattern sometime after 16 ka. Actual decline in catchment runoff, determined by comparing estimated palaeodischarge with contemporary flows upstream of the DFS where flow is confined to a single channel, indicate contemporary discharge to be 0.1 times and 0.25 times that of the Coocalla and Kamilaroi, respectively. The chronology presented here shows periods of increased discharge in the Gwydir to be more or less coincident with those observed elsewhere in the Murray Darling Basin. Although no evidence of a 'Gum Creek' fluvial phase (from 35 to 25 ka) was found, the Coocalla and Kamilaroi palaeochannel systems broadly conform in age to 'Kerarbury' and 'Yanco' fluvial phases on the Murrumbidgee and Murray systems. This synchronicity with more southern catchments supports the hypothesis that La Nina - like conditions were semi-permanent for much of the Last Glacial cycle with moisture derived largely from the western Pacific Ocean.

Pietsch, Timothy J.; Nanson, Gerald C.; Olley, Jon M.

2013-06-01

175

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

SciTech Connect

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.

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

1988-02-01

176

Hydrological and sedimentological variability of the peri-fluvial wetlands of the middle Loire river (France)  

NASA Astrophysics Data System (ADS)

With a catchment basin of 112,120 km^2 and a length of 1012 km, the Loire River is one of the most important fluvial hydrosystems in France. Notwithstanding numerous modifications (dikes, dams, nuclear power plants, gravel extractions), the Loire River hydrology has been saved from a total regularisation. Therefore, the spatial diversity of fluvial landforms creates a patchwork of wetlands: ox-bow lakes, dewatered channels... As one aim of this work was to determine the hydrological and sedimentological processes in the various wetlands, in a context of spatial variability of the fluvial landforms, we used a pluridisciplinarity approach: geomorphology, hydrology, geochemistry. The present study has targeted the functioning between the various hydro-geomorphologic units of the floodplain (main and secondary active channels, abandoned branches and the riverbank [alluvial] and perched aquifers), with regard to the spatial heterogeneity of the different fluxes and the temporal variations of bottom water level, full-bank stage and overflow discharge. In the upper part of the study area, mobile meanders prevail. The meanders migration results in oxbow lakes and the connection between the lakes and the other water reservoirs (e.g. river- and groundwaters) induce a strong lateral variability and a time delayed water input by the river as evidenced by the different geochemical and isotopic signatures. Downstream, the Loire River develops a multiple-channels pattern, of which numerous are abandoned. They are often dewatered along the year, only reconnected to the main channel during the periods of overflow discharges and the influence of the Loire riverwater is progressively substituted by the input of groundwaters (alluvial and perched aquifers). It appears that the submersion duration and the type of connection between the wetlands and the various reservoirs (inlet or outlet connection with the river, connection with the aquifers.) strongly influence the sedimentation rate and granulometric features.

Gautier, E.; Kunesch, S.; Negrel, P.; Petelet-Giraud, E.

2003-04-01

177

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

NASA Astrophysics Data System (ADS)

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.

Yan, Zhenzhen

2014-05-01

178

External controls on Quaternary fluvial incision and terrace formation at the Segre River, Southern Pyrenees  

NASA Astrophysics Data System (ADS)

Focusing on climatic- and structural (tectonic) controls, we aim to determine their relative importance for the (Pliocene to Quaternary) fluvial landscape evolution in the Southern Pyrenees foreland. We investigate the Segre River, which is one of the major streams of the Southern Pyrenees that drains the elevated chain towards the Ebro foreland basin. Along its course, the Segre River has a flight of fluvial cut-and-fill (and strath-type) terraces preserved that have been mapped based on DEM's and geomorphological fieldwork. This paper presents the first results of our study and reports on the Segre terrace staircase, which is characterized by seven major Quaternary terrace levels with elevations up to more than 110 m above the modern floodplain. At the upper and middle reaches, the semi-parallel terraces of the Segre River occasionally show anomalies featuring extensive gravel thickness and deformation caused by faulting, folding and local subsidence. The longitudinal correlations of terrace levels reveal increased vertical terrace spacing in the foreland, which could originate from enhanced fluvial erosion after the Mid-Pleistocene climate transition in combination with base level lowering controlled by the progressive downcutting of the Catalan Coastal Range. Since the Ebro Basin opening (Late Miocene), the Catalan Coastal Range, which borders the Ebro foreland basin to the Mediterranean Sea, was progressively cut down and the exorheic drainage system gradually adjusted to sea level. The Segre longitudinal terrace profiles and the Ebro gorge morphology at the Catalan Coastal Range indicate a base-level of about 200 m.s.l. at the beginning of (Pleistocene) terrace formation, which implies that the Catalan Coastal Range might have functioned as a local base-level upstream of the sea outlet, presumably until the Late Pleistocene. Alternatively, a yet unknown tectonic process might have caused base level lowering and the preservation of terrace staircases at the Ebro drainage system.

Stange, Kurt Martin; van Balen, Ronald; Vandenberghe, Jef; Pea, Jose Luis; Sancho, Carlos

2013-08-01

179

Fluvial Erosion and Transportation of an Impact Regolith Layer: Implications for Titan  

NASA Astrophysics Data System (ADS)

Large regions of Titan appear to be eroded cratered terrain. If this is correct, then Titans surface could have been characterized by a regolith hundreds of meters thick with abundant unconsolidated debris in the size range that could be fluvially transported and serving as tools for bedrock incision. We utilized a variant on our Landform Evolution Model, originally developed to understand fluvial erosion on Mars, to study this issue. We see two end-member results. Slopes covered with coarse grained material develop a drainage network that essentially becomes stabilized after a sufficient time. They become paved with gravel that can only be eroded very slowly, if at all, after some degree of erosion. Simulations with finer sediment (for example with the maximum grain size only 16 mm) the flow can transport a good bit of sediment throughout the simulation, and drainage basins are initially created, but the topography evolves into a gentle slope of parallel drainage. For gravel channel systems under high sediment transport situations, there is no downstream concavity - the channels are essentially uniform in slope so that no drainage basins form. However, for coarser sediment we are near the threshold of motion near the end of the simulation, and channel gradients decrease downstream, implying a well-developed drainage network will form. However, if boulders are intermixed with the fines (which is reasonable), upland surfaces could eventually become mantled with a pavement of coarse debris after differential removal of transportable sediment, thus limiting net erosion unless a weathering (rock-disintegrating) process occurs on Titan. Titans fluvial networks could have been quickly established, then become somewhat impervious to further landscape evolution even if the precipitation rates and intensities persisted for long times.

Moore, Jeffrey M.; Howard, Alan D.; Breton, Sylvain

2014-11-01

180

Study on fine geological modelling of the fluvial sandstone reservoir in Daqing oilfield  

SciTech Connect

These paper aims at developing a method for fine reservoir description in maturing oilfields by using close spaced well logging data. The main productive reservoirs in Daqing oilfield is a set of large fluvial-deltaic deposits in the Songliao Lake Basin, characterized by multi-layers and serious heterogeneities. Various fluvial channel sandstone reservoirs cover a fairly important proportion of reserves. After a long period of water flooding, most of them have turned into high water cut layers, but there are considerable residual reserves within them, which are difficult to find and tap. Making fine reservoir description and developing sound a geological model is essential for tapping residual oil and enhancing oil recovery. The principal reason for relative lower precision of predicting model developed by using geostatistics is incomplete recognition of complex distribution of fluvial reservoirs and their internal architecture`s. Tasking advantage of limited outcrop data from other regions (suppose no outcrop data available in oilfield) can only provide the knowledge of subtle changing of reservoir parameters and internal architecture. For the specific geometry distribution and internal architecture of subsurface reservoirs (such as in produced regions) can be gained only from continuous infilling logging well data available from studied areas. For developing a geological model, we think the first important thing is to characterize sandbodies geometries and their general architecture`s, which are the framework of models, and then the slight changing of interwell parameters and internal architecture`s, which are the contents and cells of the model. An excellent model should possess both of them, but the geometry is the key to model, because it controls the contents and cells distribution within a model.

Zhoa Han-Qing [Daqing Research Institute, Helongjiang (China)

1997-08-01

181

Geological Relationships Between Hydrated Minerals And Fluvial Landforms In Tyrrhena Terra, Mars.  

NASA Astrophysics Data System (ADS)

The phyllosian period of Mars displays rocks that are altered at different levels, containing phyllosilicates of various nature, revealing that liquid water played a strong role in their formation. However, debates currently exist to know if this alteration was conduced at the surface due to a different climate, or in the subsurface from hydrothermal circulation. Here, we display results in the Tyrrhena Terra region, which is of interest to address this issue. Indeed, Tyrrhena Terra is located in cratered Noachian highlands in the southern hemisphere, south of Isidia Planitia and north of Hellas basin. This region displays highland terrains partially dissected by fluvial valleys and several intercrater plains. Phyllosilicates are identified by the combination of 1.9 and 2.3 micron features in the OMEGA imaging spectrometer data. They are frequently located on craters ejecta and pieces of outcrops close to the highlands. Olivine and pyroxenes are also identified, and are associated mainly to the intercrater plains when present together. We focus our interest on regions where a single 1.9 micron signature is observed (with small 2.3 micron features observed locally), and where pyroxene is found in the same area. This detection suggests a partial alteration or a spatial mixing with unaltered material as highlighted by the presence of pyroxene signatures at the same location. The geologic study of these areas of interest shows that these hydrous minerals are located at the foothills of highlands, especially in locations where valley networks end in plains. This leads to the conclusion that these hydrous minerals are observed in alluvial plains collecting material from the highlands. This example shows that external cycles of running water are involved in alteration minerals deposition. We currently study these regions in details to know if the alteration was a result of this process during sedimentation (alteration coeval to fluvial activity), or if the alteration occurred earlier in the crust with later erosion and transport into the alluvial plains (without relation with fluvial episodes).

Bouley, S.; Loizeau, D.; Mangold, N.; Poulet, F.; Ansan, V.; Le Mouelic, S.; Bibring, J.; Langevin, Y.

2008-12-01

182

Quantifying fluvial topography using UAS imagery and SfM photogrammetry  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

183

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

184

Experimental insights on the effects of varying discharge on fluvial landscape evolution  

NASA Astrophysics Data System (ADS)

River floods are known to have large impacts on fluvial morphology as the capacity to carry water and rework sediment during these events is large. However, recent experimental findings are conflicting: some suggest that varying discharge contributes to a more single-thread pattern whereas others suggest that discharge variations cause multiple threads to be active, and yet others show no significant effect on the morphology. Our objective is to study the effect of varying discharge on experimental river patterns with otherwise similar conditions, and to quantitatively compare the resulting morphology and deposits. Our experiments were conducted in a flume of 10x6 meter, which was split up into two separate fluvial plains (each 10x3 m). Fluvial landscape evolution was recorded by high-resolution line-laser scanning and digital Single Lens Reflex (SLR) camera used for channel-floodplain segmentation and particle size estimation. The bed sediment consisted of a poorly sorted sediment mixture ranging from fine sand to fine gravel. First, a braided and meandering river pattern evolved for identical and constant boundary conditions, except that slightly cohesive silt-sized silica flour was added to the feed sediment of the meandering channel. A second set of experiments had an identical cycled discharge regime with a long-duration low flow and a short-duration high flow.The varying discharge largely affected the fluvial landscape by biasing the morphology towards the high flow conditions. This was reflected by an increase of the bar wave length with nearly a factor 2. Also, the depth of maximum erosion increased, which affects the preservation potential. The meandering and braided patterns responded differently to the floods. The noncohesive sediment combination with varying discharge results in a higher degree of braiding when compared to constant discharge. This was observed as a higher number of re-activating channels during high flow. In contrast, the silica flour acted as floodplain builder, which was more efficiently distributed during floods. As a result, the system with slightly cohesive sediment remained mostly confined to one migrating meandering channel that developed scroll bars, channel fills, splays and levees. We conclude that the response to varying discharge depends on the availability and cohesion of fine floodplain-forming sediment in combination with the potential of high flows to re-activate residual channels.

van de Lageweg, W. I.; van Dijk, W. M.; Kleinhans, M. G.

2012-04-01

185

Experimental insights on the effects of varying discharge on fluvial landscape evolution  

NASA Astrophysics Data System (ADS)

River floods are known to have large impacts on fluvial morphology as the capacity to carry water and rework sediment during these events is large. However, recent experimental findings are conflicting: some suggest that varying discharge contributes to a more single-thread pattern whereas others suggest that discharge variations cause multiple threads to be active, and yet others show no significant effect on the morphology. Our objective is to study the effect of varying discharge on experimental river patterns with otherwise similar conditions, and to quantitatively compare the resulting morphology and deposits. Our experiments were conducted in a flume of 10x6 meter, which was split up into two separate fluvial plains (each 10x3 m). Fluvial landscape evolution was recorded by high-resolution line-laser scanning and digital Single Lens Reflex (SLR) camera used for channel-floodplain segmentation and particle size estimation. The bed sediment consisted of a poorly sorted sediment mixture ranging from fine sand to fine gravel. First, a braided and meandering river pattern evolved for identical and constant boundary conditions, except that slightly cohesive silt-sized silica flour was added to the feed sediment of the meandering channel. A second set of experiments had an identical cycled discharge regime with a long-duration low flow and a short-duration high flow.The varying discharge largely affected the fluvial landscape by biasing the morphology towards the high flow conditions. This was reflected by an increase of the bar wave length with nearly a factor 2. Also, the depth of maximum erosion increased, which affects the preservation potential. The meandering and braided patterns responded differently to the floods. The noncohesive sediment combination with varying discharge results in a higher degree of braiding when compared to constant discharge. This was observed as a higher number of re-activating channels during high flow. In contrast, the silica flour acted as floodplain builder, which was more efficiently distributed during floods. As a result, the system with slightly cohesive sediment remained mostly confined to one migrating meandering channel that developed scroll bars, channel fills, splays and levees. We conclude that the response to varying discharge depends on the availability and cohesion of fine floodplain-forming sediment in combination with the potential of high flows to re-activate residual channels.

van de Lageweg, W. I.; Van Dijk, W. M.; Kleinhans, M. G.

2011-12-01

186

New insights from DEM's into form, process and causality in Distributive Fluvial Systems  

NASA Astrophysics Data System (ADS)

Recent developments in platforms and sensors, as well as advances in our ability to access these rich data sources in near real time presents geoscientists with both opportunities and problems. We currently record raster and point cloud data about the physical world at unprecedented rates with extremely high spatial and spectral resolution. Yet the ability to extract scientifically useful knowledge from such immense data sets has lagged considerably. The interrelated fields of database creation, data mining and modern geostatistics all focus on such interdisciplinary data analysis problems. In recent years these fields have made great advances in analyzing the complex real-world data such as that captured in Digital Elevation Models (DEM's) and satellite imagery and by LIDAR and other geospatially referenced data sets. However, even considering the vast increase in the use of these data sets in the past decade these methods have enjoyed only a relatively modest penetration into the geosciences when compared to data analysis in other scientific disciplines. In part, a great deal of the current research weakness is due to the lack of a unifying conceptual approach and the failure to appreciate the value of highly structured and synthesized compilations of data, organized in user-friendly formats. We report on the application of these new technologies and database approaches to global scale parameterization of Distributive Fluvial Systems (DFS) within continental sedimentary basins and illustrate the value of well-constructed databases and tool-rich analysis environments for understanding form, process and causality in these systems. We analyzed the characteristics of aggradational fluvial systems in more than 700 modern continental sedimentary basins and the links between DFS within these systems and their contributing drainage basins. Our studies show that in sedimentary basins, distributive fluvial and alluvial systems dominate the depositional environment. Consequently, we have found that studies of modern tributary drainage systems in degradational settings are likely insufficient for understanding the geomorphology expressed within these basins and ultimately for understanding the basin-scale architecture of dominantly distributive fluvial deposits preserved in the rock record.

Scuderi, Louis; Weissmann, Gary; Hartley, Adrian; Kindilien, Peter

2014-05-01

187

Some observations on Titan's fluvial networks and channel/valley delineation using Cassini radar imagery  

NASA Astrophysics Data System (ADS)

Data from the Cassini-Huygens mission have revealed fluvial networks on Titans surface. Past research found that fluvial sediment transport and erosion processes at the grain scale on Titan would be comparable to similar processes on Earth [1,2]. On this basis, we assume that basin-scale fluvial processes would also be similar to terrestrial processes and that analytical approaches derived for Earth would give meaningful results for Titan. An algorithm had been developed from terrestrial data to classify fluvial networks (e.g., as dendritic, rectangular, parallel, etc.) [3]. This algorithm was simplified and has been applied to classify networks in Cassini Titan Radar Mapper synthetic aperture radar (SAR) images of Titan [4,5]. It was also uncertain how much the direction of radar illumination impacted the interpretation of features visible in the imagery; overlapping radar swaths can provide useful information about that effect. We delineated channel/valley features on several radar swaths based on the distinguishability, morphology, and illumination [3]. In recently released data, at least 2 networks containing a minimum of 7 visible links or 3 junction angles were found in swaths T41 and T44, and were analyzed using the simplified algorithm [3]. T41 overlapped with T43, and T44 overlapped with T13, allowing comparison of network delineations and analysis of the effect of illumination angle on network classification. Channel delineation in overlap areas was compared, and differences were noted. The largest differences were attributed to human delineation error, poor effective resolution, or the directions of radar illumination (Figure 1). However, they did not affect the network classification; in both T13 and T44, the networks were classified as rectangular, which is commonly caused by subsurface tectonic activity. In contrast, the networks in T41 were classified as parallel, indicating variation in the controlling factors, such as steeper terrain or less tectonic influence. References: [1] Burr, D.M. et al (2006) Icarus, 181, 235-242. [2] Collins, G.C. Geophys. Res. Lett., 32 (22).[3] Ichoku, I. & Chorowicz, J. (1994) Water Resources Research, 30, 161-174. [4] Jacobsen, R.E. et al (2008) AGU abstract#P21A-1315 [5] Burr, D.M. et al (sub. 2009) Geophys. Res. Lett. Figure 1: Channel feature visible in T13 (left) was not readily apparent in T44 (right) due to the direction of radar illumination (see arrows).

Viola, D.; Burr, D. M.; Phillips, C. B.

2009-12-01

188

Fluvial armor  

Microsoft Academic Search

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

G. Parker; A. J. Sutherland

1990-01-01

189

-1 -jorgemercau@gmail.com gea.unsl.edu.ar Integrando al agua en las decisiones  

E-print Network

- 1 -jorgemercau@gmail.com gea.unsl.edu.ar Integrando al agua en las decisiones Producción y Lluvia #12;- 3 -jorgemercau@gmail.com gea.unsl.edu.ar Radiación, Temperatura (10d) y fotoperíodo 5 10 15 D E F M A M mm/mes Pp Etp ... ¿Cuándo siembro? Rendimiento potencial Oferta vs Demanda ¿Cuanta agua

Nacional de San Luis, Universidad

190

Tertiary fluvial systems within the Bear Creek coal field, northern Big Horn basin, Montana  

SciTech Connect

The Bear Creek coal field contains the 250-m-thick coal-bearing Paludal Member of the Paleocene Fort Union Formation in the northern Big Horn Basin, Montana. Detailed field and subsurface data show two contrasting geometries in alluvial strata, each bounded by an economic coal bed. The lower 50 m of the Paludal Member is dominated by sheet and ribbon sandstones. The sheet sandstones are as long as 1.5 km and fine upwards from medium to fine grained. Some sandstones are multistory with sharp upoper and lower contacts. The upper portion has convolute bedding, ripple lamination, and some horizontal and tabular crossbeds. Stratigraphically higher is a 12-m-thick fine-grained sequence, containing large tree trunks in growth position and extensively rooted mud rocks. Sandstone bodies, 6 m thick and 10 m wide, are enclosed within mudstones and siltstones. The sandstones are primarily ripple laminated and have stepped bases and internal erosion surfaces. This interval has previously been interpreted as deposits of an anastomosed fluvial system. The sandstones show little evidence of significant lateral migration. In contrast to the lower interval, the environment here consisted of well-developed vegetated islands separating fluvial channels. Subsurface data show that the major coal beds are laterally continuous within the study area. The cyclic development of the coals reflects intermittent periods of long-term basin stability. Alternating dominance of the sandstones suggests that influx and distribution were controlled through episodic uplift of the nearby Beartooth Mountains.

Weaver, J.N. (Geological Survey, Denver, CO (United States)); Gruber, J.R. Jr. (Bureau of Land Management, Billings, MT (United States))

1991-06-01

191

Structural control of fluvial drainage in the western domain of the Cape Fold Belt, South Africa  

NASA Astrophysics Data System (ADS)

The purpose of the study was to examine the extent to which drainage morphology has been influenced by faulting, folding and bedrock lithology in the Cape Fold Belt (CFB) of South Africa. This region was formed during Paleozoic-Mesozoic convergence along the south-western margin of Gondwana. An extensive structural geology database, terrain characteristics and stream network data were analysed using Geographical Information Systems (GIS) to examine the possible linkages between structure and fluvial drainage. Results indicated that the contemporary geomorphology of the area reflects the influence of folding and faulting as well as differential erosion. The following drainage anomalies suggestive of strong structural control were identified: orientation of flow direction of major streams corresponding to structural lineaments, abrupt changes in stream direction influenced by anticline fold axes, faults and joints, and fault-aligned streams. Drainage development in the study area responded noticeably to the underlying structure. The study raises questions with regard to the implications of one major or multiple dominant structural controls on drainage morphology and pattern. The findings have relevance with regard to the understanding fluvial drainage development and landform evolution in tectonically deformed regions.

Manjoro, Munyaradzi

2015-01-01

192

An inventory of published and unpublished fluvial-sediment data for California, 1956-70  

USGS Publications Warehouse

This inventory was prepared to provide a convenient reference to published and unpublished fluvial-sediment data for water years 1956-70, and updates substantially previous inventories. Sediment stations are listed in downstream order, and an alphabetical list of stations is also included. Figure 1 shows the approximate location of sediment stations in California. Most of the fluvial-sediment data in California were collected by the U.S. Geological Survey, under cooperative agreements with the following Federal, State, and local agencies: California Department of Water Resources, California Department of Navigation and Ocean Development, California Department of Fish and Game, Bolinas Harbor District, Monterey County Flood Control and Water Conservation District, Orange County Flood Control District, Riverside County Flood Control and Water Conservation District, San Diego County Department of Sanitation and Flood Control, San Luis Obispo County, San Mateo County, Santa Clara County Flood Control and Water District, Santa Cruz County Flood Control and Water Conservation District, Santa Cruz, city of, University of California, Ventura County Flood Control District, Forest Service, U.S. Department of Agriculture, Soil Conservation Service, U.S. Department of Agriculture, Corps of Engineers, U.S. Army, Bureau of Reclamation, U.S. Department of the Interior, National Park Service, U.S. Department of the Interior. This report was prepared by the Geological Survey under the general supervision of R. Stanley Lord, district chief in charge of water-resources investigations in California.

Porterfield, George

1972-01-01

193

Influence of composition and temperature on hydrocarbon migration through Morrow fluvial reservoirs, Las Animas Arch, Colorado  

SciTech Connect

Precipitation of wax in pores may impair permeability and prohibit the flow of oil. Crude oil composition and temperature are the most important controlling factors. Oils are chemically complex, may contain up to 45 wax compounds and may vary significantly even in the same pool. High-wax oils are common in the Morrow of eastern Colorado. Narrow fluvial sandstones provide migration paths toward the Las Animas Arch from adjacent basins. Temperatures range from less than 110{degrees}F. on the top of the arch to 180{degrees}F at a structural position only 1,400 feet lower. A range of 30{degrees}F has been observed in individual pools. Wax has precipitated in the 120-140{degrees}F range, creating relative permeability barriers which cut across the sandstones. Wax barriers are impermeable to oil, but may be permeable to gas and water. They account for certain dry holes with high porosity, permeability and oil saturation (and low water saturation) in both core and electrical log analysis. They explain why some oil wells with impaired permeability are adjacent to structurally lower gas wells with good permeability. A network of wax barriers around the Las Animas Arch accounts for approximately 300 feet of variation in the structural position of a line separating oil from gas fields. Since the low temperature bands may be short and discontinuous, wax barriers are more effective in narrow fluvial reservoirs than in blanket reservoirs.

Bolyard, D.W. [Consultant, Denver, CO (United States)

1995-06-01

194

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

SciTech Connect

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.

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

195

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

196

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

NASA Technical Reports Server (NTRS)

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,

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

2003-01-01

197

Modern Landform Distribution of the Gilbert River Distributive Fluvial System (DFS) and Predictions Regarding Ancient Coastal Plain Progradational Successions  

NASA Astrophysics Data System (ADS)

Distributive fluvial systems (DFSs) are modern fluvial deposits of radial distributive channel patterns and encompass a continuum from small-scale alluvial fans to large-scale fluvial megafans. Given that DFSs have been shown to comprise most continental regimes, we hypothesize that these systems form fluvial deposits in sedimentary basins at the fluvial-marine interface. Few modern examples of DFSs spanning this realm exist, as modern coastlines are presently flooded due to high-amplitude Quaternary sea level changes. The Gilbert River DFS of north Queensland, Australia, represents a modern example of a DFS terminating in the Gulf of Carpentaria. Remote sensing analyses on this system show the same recognizable depositional patterns as purely continental DFS: 1) a radial channel pattern originating from an apex, 2) a down-DFS decrease in both channel and grain size, 3) a lack of lateral channel confinement, 4) a broad fan shape, and 5) a down-DFS increase in floodplain/channel area ratio. The distal portion (influenced by sea level changes) exhibits: a) a sharp contact between DFS and marginal-marine deposits, b) channel incision, confinement and lateral movement, c) channel width increasing due to tidal influence, d) sediment redistribution (spits, small-scale deltas), and e) shoreline progradation (wave-cut platforms and beach ridges). These observations ultimately lead to sedimentologic and stratigraphic predictions regarding coastal DFS deposits in the geologic record. Data from the Gilbert system are compared with facies and facies transitions in Cordilleran foreland basin Cretaceous strata that cross the fluvial-marine interface, such as the John Henry Mbr. of the Straight Cliffs Formation and the Williams Fork Formations of Utah and Colorado, respectively. If these strata are DFS, then the following succession (in ascending order) should exist in a single progradational succession: 1) Distal channel deposits with evidence of tidal influence (herringbone cross-stratification, brackish fossils, inclined heterolithic stratification) that cut into underlying foreshore strata and laterally equivalent fine-grained strata, overlain by 2) medial deposits of coarsening-upward packages due to avulsion and well-developed, laterally extensive mature paleosols, topped by 3) proximal deposits consisting of amalgamated sandstone bodies separated by regionally discontinuous erosional surfaces and relatively rare, well-drained, immature paleosols. Thus, progradational successions should exhibit an upsection increase in grain size, sand:mud ratios, and channel downcutting. Coastal plain fluvial and marginal marine progradational successions have proven to be important hydrocarbon and carbon dioxide sequestration reservoirs, coal accumulations, and aquifers. However, existing fluvial facies models used to predict sandbody distribution and connectivity are typically based on aggradational valley fill successions at the outcrop- and borehole-scale.

McNamara, K. C.; Weissmann, G. S.; Scuderi, L. A.; Owen, A.; Nichols, G. J.; Hartley, A. J.

2011-12-01

198

VOIES NAVIGABLES ET DESSERTE PORTUAIRE Massifier les flux pour intgrer le transport fluvial dans les chanes logistiques portuaires : tude des impacts conomiques et environnementaux. Le cas du transport fluvial conteneuris  

Microsoft Academic Search

Le programme de recherche partait de l'hypothse que le transport fluvial combin fleuveroute pour le transport de conteneurs pouvait s'imposer comme un mode de transport comptitif par rapport la route partir du moment o il jouait sur son principal atout qui tait celui de la massification des flux. Grce nos travaux, nous avons pu mettre en vidence,

Antoine Frmont; Pierre Franc

2008-01-01

199

Case study of climatic changes in Martian fluvial systems at Xanthe Terra  

NASA Astrophysics Data System (ADS)

An unnamed valley system was analyzed in Xanthe Terra south of Havel Vallis on Mars where three separate episodes of fluvial activity could be identified with different morphology, water source and erosional processes, inferring formation under different climatic conditions. The oldest scattered valleys (1. group) form interconnecting network and suggest areally distributed water source. Later two valley types formed from confined water source partly supported by possible subsurface water. The smaller upper reaches (2. group) with three separate segments and also a similar aged but areal washed terrain suggest contribution from shallow subsurface inflow. These valleys fed the main channel (3. group), which morphology (wide, theater shaped source, few tributaries, steep walls) is the most compatible with the subsurface sapping origin. While the first valley group formed in the Noachian, the other two, more confined groups are younger. Their crater density based age value is uncertain, and could be only 1200 million years. After these three fluvial episodes etch pitted, heavily eroded terrain formed possibly by ice sublimation driven collapse. More recently (60-200 million years ago) dunes covered the bottom of the valleys, and finally the youngest event took place when mass movements produced debris covered the valleys' slopes with sediments along their wall around 5-15 million years ago, suggesting wind activity finished earlier than the mass movements in the region. This small area represents the sequence of events probably appeared on global scale: the general cooling and drying environment of Mars. Comparing the longitudinal profiles here to other valleys in Xanthe Terra, convex shaped valley profiles are usually connected to steep terrains. The location of erosional base might play an important role in their formation that can be produced convex shapes where the erosional base descended topographically (by deep impact crater or deep outflow channel formation) as time passed by. The analysis of such nearby systems that probably witnessed similar climatic forces in the past, provides ideal possibility to identify reasons and geomorphological context of longitudinal profile shape formation for fluvial valleys in general. Three different groups of valleys were identified at a system in Xanthe Terra. The oldest scattered valleys formed by areal water source. Younger upper reaches might form by linear and areal flow, lower reaches by sapping. Crater density based ages are uncertain, but point to activity 600-1200 million years ago. Dunes are 60-200, talus slopes are 5-15 million years old in the valleys.

Kereszturi, Akos

2014-06-01

200

Influence of fluvial processes on the quaternary geologic framework of the continental shelf, North Carolina, USA  

USGS Publications Warehouse

Digital, single-channel, high-resolution seismic reflection profiles were acquired from the insular continental shelf of North Carolina, USA along a data grid extending from Oregon Inlet northward 48 km to Duck, North Carolina and from the nearshore zone seaward approximately 28 km (total surveyed area= 1334 km2). These data were processed and interpreted to delineate principal reflecting horizons and develop a three-dimensional seismic stratigraphic framework for the continental shelf that was compared to stratigraphic data from the shoreward back-barrier (estuarine) and barrier island system. Six principal reflecting horizons (designated R0 through R5) were present within the upper 60 m of the shelf stratigraphic succession. Three-dimensional mapping of reflector R1 demonstrated its origin from fluvial incision of the continental shelf during an episode (or episodes) of lowered sea-level. Fluvial processes during development of reflector R1 were responsible for extensive reworking and re-deposition of sediment throughout most of the northern half of the study area. Five seismic stratigraphic units (designated S1 through S5) were tentatively correlated with depositional sequences previously identified from the North Carolina back-barrier (estuarine) and barrier island system. These five stratigraphic units span the Quaternary Period (S1 = early Holocene; S2 = 51-78 ka; S3 = 330-530 ka; S4 = 1.1-1.8 Ma; S5 = earliest Pleistocene). Unit S1 is composed of fine-grained fluvial/estuarine sediment that back-filled incised streams during early Holocene sea-level rise. The four other stratigraphic units (S2-S5) display tabular depositional geometries, low total relief, and thicken toward the east-southeast as their basal reflectors dip gently between 0.41 m km-1 (0.02??) and 0.54 m km-1 (0.03??). Knowledge of the three-dimensional subsurface stratigraphic architecture of the continental shelf enhances understanding of the development of shelf depositional successions and provides a framework for development of better Quaternary sea-level data, especially offshore North Carolina where such data are sparse. ?? 2002 Elsevier Science B.V. All rights reserved.

Boss, S.K.; Hoffman, C.W.; Cooper, B.

2002-01-01

201

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

202

Late Pleistocene differential uplift inferred from the analysis of fluvial terraces (southern Apennines, Italy)  

NASA Astrophysics Data System (ADS)

The stratigraphic architecture and morphological assemblage of the Pleistocene fluvial terraces contained in two contiguous fluvial valleys are used to understand the spatial distribution and the timing of the differential uplift that affected two different geological and geomorphological settings of an active orogen. The study areas, both placed in the eastern sector of the southern Apennines of Italy, are the Sant'Arcangelo sedimentary basin and the Valsinni Ridge anticline. Pleistocene uplift rate of 0.7-0.9 mm y- 1 and historical earthquakes affecting those areas suggest active tectonics. Based on the synthem units used to classify the fluvial deposits in the field, several strath, fill, and fill-cut terraces have been mapped in the middle valleys of the Agri and Sinni rivers. Four Middle Pleistocene high terraces (Qes) are found in the Sant'Arcangelo Basin and cut its infill, and three Late Pleistocene low terraces (Qt) are found at both the Agri and Sinni valley flanks. The Agri and Sinni rivers cross-cut the NW-SE-oriented fold-and-thrust belt of the southern Apennines from W to E, producing a transverse drainage. As a result, ten- to hundred-metre deep gorges and wide floodplains were created in the middle reach of the river valleys. Computation of the bedrock incision rates from the Qes1, Qes4, and SQt1 terraces, corresponding to 1.2 0.2 mm y- 1 at 400-240 ka and 0.8 0.2 mm y- 1 in the last 240 ka, together with the terrace profile arrangements in the Agri and Sinni valleys, allow for the documentation of i) the differential uplift of the study area and ii) the age of terrace abandonment corresponding to the beginning age of the vertical incision in the valley floor sediments to form the Qt terraces. The differential uplift is subsequently discussed in a space and time-sequence evolution of the Late Pleistocene to assess the complex morphotectonic development that occurred in the eastern threshold of the basin. The differential uplift of both the Sant'Arcangelo Basin and Valsinni Ridge would appear to indicate that buried fold-and-thrust structures that affect the Mesozoic-Cenozoic sedimentary nappes are still active, and they also controlled the slab retreat processes in the Mediterranean region during the Late Pleistocene.

Giano, Salvatore Ivo; Giannandrea, Paolo

2014-07-01

203

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

NASA Astrophysics Data System (ADS)

Palynostratigraphic and sedimentary facies analyses were made on sedimentary deposits from the left bank of the Solimes 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.

Dino, Rodolfo; Soares, Emlio Alberto Amaral; Antonioli, Luzia; Riccomini, Claudio; Nogueira, Afonso Csar Rodrigues

2012-03-01

204

Sequence stratigraphic-structural analysis of the East Midlands Carboniferous oil field, UK: Implications for fluvial reservoir models  

Microsoft Academic Search

The integration of seismic, well log and core data from, the Scampton North and Welton oil fields, Lincolnshire, UK, has enabled the development of a sequence stratigraphic-structural model for late Namurian and early Westphalian fluvial reservoirs. The tectonic and sequence stratigraphic setting is remarkably similar to that in the Southern North Sea which extends more than 250 km to the

J. F. Aitken; D. G. Quirk

1996-01-01

205

Development a fluvial detachment rate model to predict the erodibility of cohesive soils under the influence of seepage  

Technology Transfer Automated Retrieval System (TEKTRAN)

Seepage influences the erodibility of streambanks, streambeds, dams, and embankments. Usually the erosion rate of cohesive soils due to fluvial forces is computed using an excess shear stress model, dependent on two major soil parameters: the critical shear stress (tc) and the erodibility coefficie...

206

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

207

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

USGS Publications Warehouse

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.

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

2002-01-01

208

Insight into past hydrological conditions through signatures of stables isotopes in Holocene Loire River fluvial sediments (France)  

E-print Network

River fluvial sediments (France) Philippe Négrel Wolfram Kloppmann BRGM, Orléans, France Multi-proxy indices (18 O, 13 C, granulometry, mineralogy) in the sediments from a channel infill in the Middle Loire. BP. The Loire River in central France is 1010 km long and drains an area of 117,800 km2

Paris-Sud XI, Université de

209

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

E-print Network

T. Sloan1 * The movement of fluvial sediment shapes our rivers. Understanding sediment entrainment . In natural river settings, however, sediments are invariably covered by bacteria, often forming visible processes and on human exploitation of rivers. Scour, transport and deposition of sediment can act to render

Luo, Xiaoyu

210

Unconfined flow deposits in distal sectors of fluvial distributary systems: Examples from the Miocene Luna and Huesca Systems, northern Spain  

NASA Astrophysics Data System (ADS)

Thin sheet sandstone beds in a continental succession may be the products of unconfined overbank flow or deposition in lacustrine environments. In the distal parts of fluvial distributary systems these two settings may be intercalated, recording fluctuations in lake level in response to climatic changes. Field studies of the Luna and Huesca fluvial distributary systems in the Miocene of the Ebro Basin, Spain, are here used to characterise sheet sandstone deposited in distal fluvial and lake margin environments. In this study we document the facies and relationships between 322 individual sandbodies deposited in both alluvial settings as sheetfloods and in lacustrine settings as deltaic lobes. The alluvial sandstone sheets were deposited from lateral and frontal sheetflood events when unconfined flow replaced channelised flow as the main transport mechanism. The term sheetflood is used here to refer to sub-aerial, unconfined, turbulent flow events that undergo expansion, thinning and deceleration with increasing radial distance from source. The depositional process is similar to modern "floodouts" and "terminal splays" of the Channel Country and Lake Eyre, central Australia. Such a process was thought to be the dominant depositional mechanism during lake lowstands. The sheets formed in the lacustrine setting are interpreted as deltaic sediments deposited in a shallow-gradient lake similar to the modern day Volga Delta, Caspian Sea. Shallow-water, friction-dominated, deltaic processes are thought to have been the primary depositional mechanism in the distal sectors of the fluvial systems during lake highstands.

Fisher, J. A.; Nichols, G. J.; Waltham, D. A.

2007-02-01

211

HOW WELL DO THE ROSGEN CLASSIFICATION AND ASSOCIATED "NATURAL CHANNEL DESIGN" METHODS INTEGRATE AND QUANTIFY FLUVIAL PROCESSES AND CHANNEL RESPONSE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Over the past 10 years the Rosgen classification system and its associated methods of 'natural channel design' have become synonymous (to many without prior knowledge of the field) with the term 'stream restoration' and the science of fluvial geomorphology. The classification system define nine maj...

212

Restoration of riparian vegetation in the south-western United States: importance of flow regimes and fluvial dynamism  

Microsoft Academic Search

Riparian ecosystems in the south-western United States have undergone extensive physical and biological changes, due, in part, to alteration of natural flow regimes and suppression of fluvial processes. Many riparian ecosystem restoration projects are achieving success because they recognize the importance of restoring the hydrologic regime. In other words, these projects are restoring flows of water and sediment in sufficient

Juliet C. Stromberg

2001-01-01

213

Temporal Reproductive Separation of Fluvial Yellowstone Cutthroat Trout from Rainbow Trout and Hybrids in the Yellowstone River  

Microsoft Academic Search

Yellowstone cutthroat trout Oncorhynchus clarkii bouvierii are genomically extinct throughout much of their historic range because of displacement by and introgression with introduced rainbow trout O. mykiss. However, fluvial Yellowstone cutthroat trout still retain their genetic integrity while coexisting with rainbow trout in the Yellowstone River. We assessed whether spatial or temporal reproductive isolation, or both, occurs between these taxa.

James N. DeRito; Alexander V. Zale; Bradley B. Shepard

2010-01-01

214

Shallow Fluvial valleys on Alba Patera, Mars from HRSC/MEX analysis: Limited snowmelt episode  

NASA Astrophysics Data System (ADS)

The distribution of valley networks on whole Alba Patera and their pattern suggest that they formed by runoff controlled by topographic slope and lithology. However, 3D characteristics of valleys do not suggest a sustained fluvial activity unlike what we could derive by their 2D properties such as the high drainage density. Episodic snowmelt following snow deposition could be at the origin of these shallow valleys. Melting can be due either to the volcano geothermal activity (valleys possibly formed coevally to volcanic activity), or to transient climatic episodes during the Late Hesperian/Early Amazonian periods that may have been recorded in other locations on Mars. Relationships with ice-rich mantling and age of valleys are not consistent with a melting of this mantling deposited during periods of high obliquity [7] in the recent history of Mars [8]. EPSC Abstracts Vol. 6, EPSC-DPS2011-1742, 2011 EPSC-DPS Joint Meeting 2011 c Author(s) 2011

Ansan, V.; Mangold, N.

2011-10-01

215

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

SciTech Connect

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.

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

216

Geoarchaeology, the four dimensional (4D) fluvial matrix and climatic causality  

NASA Astrophysics Data System (ADS)

Geoarchaeology is the application of geological and geomorphological techniques to archaeology and the study of the interactions of hominins with the natural environment at a variety of temporal and spatial scales. Geoarchaeology in the UK over the last twenty years has flourished largely because it has gone beyond technological and scientific applications. Over the same period our ability to reconstruct the 3-dimensional stratigraphy of fluvial deposits and the matrix of fluvial sites has increased dramatically because of a number of technological advances. These have included the use of LiDAR (laser imaging) and radar to produce high-resolution digital surface models, the use of geophysics, particularly ground penetrating radar and electrical resistivity, to produce sediment depth models, and the use of GIS and data visualisation techniques to manipulate and display the data. These techniques along with more systematic and detailed sedimentological recording of exposed sections have allowed the construction of more precise 3-dimensional (volumetric) models of the matrix of artefacts within fluvial deposits. Additionally a revolution in dating techniques, particularly direct sediment dating by luminescence methods, has enabled the creation of 4-dimensional models of the creation and preservation of these sites. These 4-dimensional models have the ability to provide far more information about the processes of site creation, preservation and even destruction, and also allow the integration of these processes with independent data sources concerning cultural evolution and climatic change. All improvements in the precision of dating fluvial deposits have archaeological importance in our need to translate events from a sequential or geological timeframe to human timescales. This allows geoarchaeology to make a more direct contribution to cultural history through the recognition of agency at the individual or group level. This data can then form a component of biocomplexity or agent-based modelling which is becoming increasingly used in the natural sciences, particularly ecology and geomorphology and which can be used to test scenarios including the impact on, and response of, hominins to abrupt or catastrophic environmental change. Whilst catastrophic events clearly represent the atypical they can be illuminating in revealing cognitive processes resulting in abandonment, coping, mitigation and innovation. These points are exemplified using two in-depth case studies: one from the Holocene geoarchaeological record of the River Trent in Central England and the other from the Palaeolithic record from rivers in South West Britain. In the former the interaction between climate change and human activity is illustrated at the year to century timescale whilst in the other the timescale is millennial. These case studies have deliberately been chosen to be as different as possible in temporal and spatial scale with the aim of examining the applicability of methodological and theoretical aspects of geoarchaeology. Lastly the paper considers the problem of scale in geoarchaeology and concludes it is process-dependency, which ultimately affects the questions we can ask, and that questions of human response to climate change are fundamentally a product of materiality and cognitive processes. This demands an in-depth contextual approach to such questions rather than database-driven assertions of causality.

Brown, A. G.

2008-10-01

217

Stream restoration in dynamic fluvial systems: Scientific approaches, analyses, and tools  

NASA Astrophysics Data System (ADS)

In the United States the average annual investment in river restoration programs is approximately $1 billion. Despite this burgeoning industry, the National Water Quality Inventory, which tracks the health of the nation's rivers, has shown no serious improvement in cumulative river health since the early 1990s. In the AGU monograph Stream Restoration in Dynamic Fluvial Systems: Scientific Approaches, Analyses, and Tools, editors Andrew Simon, Sean J. Bennett, and Janine M. Castro pull together the latest evidence-based understanding of stream restoration practices, with an aim of guiding the further development of the field and helping to right its apparently unsuccessful course. In this interview, Eos talks to Sean J. Bennett, University of Buffalo, about the culture, practice, and promise of restoring rivers.

Schultz, Colin

2012-04-01

218

Rock magnetic study of fluvial Holocene soil from Buenos Aires province (Argentina)  

NASA Astrophysics Data System (ADS)

The magnetic characteristics of soils are widely used in environmental and paleoclimatic investigations for studying the several factors involved in the soil formation process. We propose here a new analytical tool that takes into account the variations in magnetic properties correlated with grain sizes and concentrations of ferrimagnetic minerals. This analytical tool is based on a mathematical model of well-established magnetic properties in samples of known grain sizes and was used in this study to determine changes in the grain size and concentration of ferrimagnetic minerals along a terminal Pleistocene/Holocene fluvial section located in the northeast of Buenos Aires province. These variations may reflect a humid period prevailing in the area and may be associated with climate changes that occurred in the Chaco-Pampean region during the Middle Holocene.

Vasquez, Carlos A.; Nami, Hugo G.

2006-10-01

219

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

USGS Publications Warehouse

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

Hindall, S.M.

1991-01-01

220

Climatic implications of correlated upper Pleistocene glacial and fluvial deposits on the Cinca and Gallego rivers, NE Spain  

SciTech Connect

We correlate Upper Pleistocene glacial and fluvial deposits of the Cinca and Gallego River valleys (south central Pyrenees and Ebro basin, Spain) using geomorphic position, luminescence dates, and time-related trends in soil development. The ages obtained from glacial deposits indicate glacial periods at 85 {+-} 5 ka, 64 {+-} 11 ka, and 36 {+-} 3 ka (from glacial till) and 20 {+-} 3 ka (from loess). The fluvial drainage system, fed by glaciers in the headwaters, developed extensive terrace systems in the Cinca River valley at 178 {+-} 21 ka, 97 {+-} 16 ka, 61 {+-} 4 ka, 47 {+-} 4 ka, and 11 {+-} 1 ka, and in the Gallego River valley at 151 {+-} 11 ka, 68 {+-} 7 ka, and 45 {+-} 3 ka. The times of maximum geomorphic activity related to cold phases coincide with Late Pleistocene marine isotope stages and heinrich events. The maximum extent of glaciers during the last glacial occurred at 64 {+-} 11 ka, and the terraces correlated with this glacial phase are the most extensive in both the Cinca (61 {+-} 4 ka) and Gallego (68 {+-} 7 ka) valleys, indicating a strong increase in fluvial discharge and availability of sediments related to the transition to deglaciation. The global Last Glacial Maximum is scarcely represented in the south central Pyrenees owing to dominantly dry conditions at that time. Precipitation must be controlled by the position of the Iberian Peninsula with respect to the North Atlantic atmospheric circulation system. The glacial systems and the associated fluvial dynamic seem sensitive to (1) global climate changes controlled by insolation, (2) North Atlantic thermohaline circulation influenced by freshwater pulses into the North Atlantic, and (3) anomalies in atmospheric circulation in the North Atlantic controlling precipitation on the Iberian peninsula. The model of glacial and fluvial evolution during the Late Pleistocene in northern Spain could be extrapolated to other glaciated mountainous areas in southern Europe.

Lewis, Claudia J [Los Alamos National Laboratory; Mcdonald, Eric [NON LANL; Sancho, Carlos [NON LANL; Pena, Jose- Luis [NON LANL

2008-01-01

221

Fluvial response to Holocene volcanic damming and breaching in the Gediz and Geren rivers, western Turkey  

NASA Astrophysics Data System (ADS)

This study discusses the complex late Holocene evolution of the Gediz River north of Kula, western Turkey, when a basaltic lava flow dammed and filled this river valley. Age control was obtained using established and novel feldspar luminescence techniques on fluvial sands below and on top of the flow. This dating constrained the age of the lava flow to 3.0-2.6 ka. Two damming locations caused by the lava flow have been investigated. The upstream dam caused lake formation and siltation of the upstream Gediz. The downstream dam blocked both the Gediz and a tributary river, the Geren. The associated lake was not silted up because the upstream dam already trapped all the Gediz sediments. Backfillings of the downstream lake are found 1.5 km upstream into the Geren valley. The downstream dam breached first, after which the upstream dam breached creating an outburst flood that imbricated boulders of 10 m3 size and created an epigenetic gorge. The Gediz has lowered its floodplain level at least 15 m since the time of damming, triggering landslides, some of which are active until present. The lower reach of the Geren has experienced fast base level lowering and changed regime from meandering to a straight channel. Complex response to base level change is still ongoing in the Geren and Gediz catchments. These findings are summarized in a diagram conceptualizing lava damming and breaching events. This study demonstrates that one lava flow filling a valley floor can block a river at several locations, leading to different but interrelated fluvial responses of the same river system to the same lava flow.

van Gorp, W.; Veldkamp, A.; Temme, A. J. A. M.; Maddy, D.; Demir, T.; van der Schriek, T.; Reimann, T.; Wallinga, J.; Wijbrans, J.; Schoorl, J. M.

2013-11-01

222

Contrasting vulnerability of drained tropical and high-latitude peatlands to fluvial loss of stored carbon  

NASA Astrophysics Data System (ADS)

sequestration and storage in peatlands rely on consistently high water tables. Anthropogenic pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of peat-forming vegetation and exposure of previously anaerobic peat to aerobic decomposition. This can shift peatlands from net CO2 sinks to large CO2 sources, releasing carbon held for millennia. Peatlands also export significant quantities of carbon via fluvial pathways, mainly as dissolved organic carbon (DOC). We analyzed radiocarbon (14C) levels of DOC in drainage water from multiple peatlands in Europe and Southeast Asia, to infer differences in the age of carbon lost from intact and drained systems. In most cases, drainage led to increased release of older carbon from the peat profile but with marked differences related to peat type. Very low DOC-14C levels in runoff from drained tropical peatlands indicate loss of very old (centuries to millennia) stored peat carbon. High-latitude peatlands appear more resilient to drainage; 14C measurements from UK blanket bogs suggest that exported DOC remains young (<50 years) despite drainage. Boreal and temperate fens and raised bogs in Finland and the Czech Republic showed intermediate sensitivity. We attribute observed differences to physical and climatic differences between peatlands, in particular, hydraulic conductivity and temperature, as well as the extent of disturbance associated with drainage, notably land use changes in the tropics. Data from the UK Peak District, an area where air pollution and intensive land management have triggered Sphagnum loss and peat erosion, suggest that additional anthropogenic pressures may trigger fluvial loss of much older (>500 year) carbon in high-latitude systems. Rewetting at least partially offsets drainage effects on DOC age.

Evans, Chris D.; Page, Susan E.; Jones, Tim; Moore, Sam; Gauci, Vincent; Laiho, Raija; Hruka, Jakub; Allott, Tim E. H.; Billett, Michael F.; Tipping, Ed; Freeman, Chris; Garnett, Mark H.

2014-11-01

223

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

224

Weathering, erosion and fluvial transfers of particulate and dissolved materials from the Taiwan orogen  

NASA Astrophysics Data System (ADS)

Systematic monitoring of river loads helps refine and extend the map of internal dynamics and external feedbacks in Earth's surface and near-surface system. Our focus is on Taiwan where hillslope mass wasting and fluvial sediment transport are driven by earthquakes and cyclonic storms. The biggest trigger events cause instantaneous erosion and seed a weakness in the landscape that is removed over time in predictable fashion. This gives rise to patterns of erosion that can not be understood in terms of bulk characteristics of climate, such as average annual precipitation. Instead, these patterns reflect the distribution and history of seismicity and extreme precipitation. For example, the 1999 Mw 7.6 Chi-Chi earthquake has resulted in elevated rates of sediment transport that decayed to normal values over seven years since the earthquake. Very large typhoons, with enhanced precipitation due to a monsoonal feed, have caused a similar, temporary deviation from normal catchment dynamics. Crucially, these events do not only mobilize large quantities of clastic sediment, but they also harvest particulate organic carbon (POC) from rock mass, soils and the biosphere. In Taiwan, most non-fossil POC is carried in hyperpycnal storm floods. This may promote rapid burial and preservation of POC in turbidites, representing a draw down of CO2 from the atmosphere that is potentially larger than that by silicate weathering in the same domain. Oxidation of fossil POC during exhumation and surface transport could offset this effect, but in Taiwan the rate of preservation of fossil POC is extremely high, due to rapid erosion and short fluvial transfer paths. Meanwhile, coarse woody debris flushed from the Taiwan mountains is probably not buried efficiently in geological deposits, representing a concentrated flux of nutrients to coastal and marine environments instead.

Hovius, Niels; Galy, Albert; Hilton, Robert; West, Joshua; Chen, Hongey; Horng, Ming-Jame; Chen, Meng-Chiang

2010-05-01

225

Outflow channels with deltaic deposits on Mars: Evidence for fluvial flows rather than volcanic flows  

NASA Astrophysics Data System (ADS)

Outflow channels are broad fluvial landforms formed by catastrophic flows with typical braided pattern. A controversy exists about their origin as aqueous flows because recent works have observed volcanic processes creating similar landforms, for example on Mercury. One caveat of the aqueous flows hypothesis is the lack of deltaic deposits that should be associated with deposition of transported material. Postflow filling can hide these deltas subsequently, but this should not be the case for 100% of outflow activity. We show from a newly found series of outflow that some outflow channels can display features typical of aqueous deposits. A connected series of outflow channels in the Ismenius Lacus quadrangle are identified for the first time and characterized using High Resolution Stereo Camera images of Mars Express and Context camera images of Mars Reconnaissance Orbiter. These channels, which stretch over >400 km south to north and join the northern plains, were identified from braided channels, scour/groove marks, poorly sinuous valleys and depositional landforms. Discharge rates were estimated to 0.1 to 5 x 106 m3 s-1 from analysis of Mars Observer Laser Altimeter topographic data. Pathways of channels segments were extracted from topography showing a unique source at a breached crater rim, suggesting overflow from ponded depressions. A series of delta fans are observed inside depressions along the channel pathways. The presence of these deltas formed in former transient bodies of water is a compelling argument for formation of this outflow channel system by fluvial flows. The similarity of these flows with other outflow channels on Mars proves that volcanically-related outflows cannot explain all channels observed on Mars. In addition, this study also shows that catastrophic floods are able to create fan deltas in transient lakes, a distinct context than usually involved for such landforms.

Mangold, Nicolas; Howard, Alan

2013-04-01

226

Interactions among Riparian Vegetation, Wood, and Fluvial Processes: a Pacific Northwest Drainage Basin Perspective  

NASA Astrophysics Data System (ADS)

Process linkages between riparian vegetation and fluvial systems can be conceptualized as a quaternary diagram with end-members representing flow rheology, channel morphology, standing riparian vegetation, and woody debris. Relationships among these four factors vary quasi-systematically as channels become progressively larger downstream, reflecting distinctive process domains. In steep, headwater catchments, channel morphology is largely determined by landslides and debris flows. These processes interact with standing and downed vegetation, which adds mass and increases battering potential while at the same time extracting momentum from flows. Experiments using a physically-based debris flow runout model demonstrate that runout distances are longer in the absence of riparian trees, although legacies of residual wood can influence runout lengths for decades. These results are supported by field evidence of substantial volumes of wood and sediment stored as debris flow deposits in low-order forested and logged catchments, and extensive swaths of uprooted and destroyed riparian forest following major floods. The influence of riparian vegetation changes as channels become progressively deeper and wider relative to tree diameter and length. Fluvial processes dominate mass movements as primary organizers of channel morphology, individual logs can be entrained and floated into accumulations and jams, and riparian vegetation adds cohesion to banks and increases hydraulic roughness for overbank flows. Architecture of woody debris deposits in streams reflects a more subtle interplay between channel bedforms and planform, and standing vegetation. Force balance models predict locations of piece entrainment and deposition to a first approximation, but rough channel margins and beds and complex hydraulics preclude accurate deterministic predictions. Further downstream, influence of riparian vegetation and woody debris on channel form diminishes, although wood may continue to play a role in nucleating and maintaining channel islands and bars.

Grant, G. E.; Lancaster, S. T.; Hayes, S.

2001-12-01

227

Fluvial drainage basins, outflow channels, and valley networks: Margaritifer Sinus, Mars  

SciTech Connect

The fluvial drainage basins of the Margaritifer Sinus Quadrangle (MC-19) are dominated by Capri and Eos Chasma and associated chaos on the northwest, by Ladon Basin in the center, and by Noachis Basin to the southeast. Laadon and Noachis are ancient, multi-ringed impact structures. The Uzboi/Ladon outflow channels are the principal drainage into Ladon Basin contributing to a major sediment sink on the central Basin plain (18/sup 0/S,29/sup 0/W). Osuga Valles outflow system (16S,39W), and some valley networks, have been beheaded by the formation of Eos Chasma. Flow out of Ladon Basin to the northeast is obscured by Margaritifer Chaos collapse. Two major longitudinal valley networks, Samara/Himera to the west and Parana/Loire to the east, dominate the drainage of eastern Margaritifer Sinus. These networks, through-going to the northwest, cross the outer ring hills of Ladon to debouch into etched terrain near Margaritifer Chaos. The Parana multi-digitate network flows into a small impact basin with a sediment sink characterized by positive relief chaos (22S,12W). Loire Valles heads in this basin; thus the authors treat Parana/Loire as a single system. Mapping with stereo pairs has allowed not only the delineation of major drainage basins, but also the identification of sub-basins, areas of internal drainage between larger basins, and determination of drainage-basin area. This mapping demonstrates that an integrated series of drainage systems with a complex fluvial history encompasses a large part of Margaritifer Sinus.

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

1985-01-01

228

Agua Caliente Wind/Solar Project at Whitewater Ranch  

SciTech Connect

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.

Hooks, Todd; Stewart, Royce

2014-12-16

229

DETERIORO DE LA CALIDAD DE LAS AGUAS DE PERCOLACION POR LA APLICACION DE LODOS DE DEPURADORA A UN SUELO AGRCOLA  

Microsoft Academic Search

RESUMEN: El posible deterioro de la calidad de las aguas subterrneas, causado por la aplicacin de lodos de depuradora a un suelo agrcola, es evaluado en trminos del incremento de la salinidad del agua de recarga y de su contenido en nutrientes. Para ello, se obtuvieron las curvas de lavado de cada elemento en estudio, a partir de un ensayo

M. J. Polo Gmez; R. Ordez Fernndez; J. V. Girldez Cerveral

230

76 FR 63614 - Agua Caliente Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Docket No. ER12-21-000] Agua Caliente Solar, LLC; Supplemental Notice That Initial...above-referenced proceeding of Agua Caliente Solar, LLC's application for market-based...accessible in the Commission's eLibrary system by clicking on the appropriate link...

2011-10-13

231

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

NASA Astrophysics Data System (ADS)

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 Volcn de Agua in Guatemala. Currently, hazard assessments of debris flows at Volcn 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 Volcn 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 Amrica (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 Volcn 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 Volcn 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 Volcn de Agua than currently exists.

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

2013-12-01

232

Middle Pleistocene to Holocene fluvial terrace development and uplift-driven valley incision in the SE Carpathians, Romania  

NASA Astrophysics Data System (ADS)

This study reveals that in the SE Carpathians terrace development and fluvial incision during the Middle Pleistocene-Holocene are predominantly controlled by tectonic uplift as shown by terrace distributions and uplift amounts and rates. The work focuses on a transect from the internal nappes and Bra?ov intramontane basin (western domain) to the external nappes and Foc?ani foredeep basin (eastern domain). New infrared stimulated luminescence ages were obtained and minimum terrace formation ages were determined to derive fluvial incision rates, and thereby, to constrain tectonic uplift. In the eastern domain, non-uniform terrace distributions in adjacent sub-parallel more active Punta and less active ?u?i?a rivers and an eastward migrated fluvial incision from the orogen to the foredeep basin indicate tectonic uplift as dominant control on terrace development. Strath-terraces in the western and eastern domains indicate repeated events of vertical fluvial incision and lateral erosion during the early Middle Pleistocene and late Middle Pleistocene-Holocene, respectively. These events imply successive recurrent disturbances of equilibrium conditions due to pulses of increased tectonic uplift. Fill-terraces in the western domain show that initial aggradation periods were followed by uplift-driven vertical incision during the late Middle-Late Pleistocene. As fill-terraces show a wide-spread development, climatic change and complex response cannot be excluded as contributing factors. Synchronous to terrace development, loess deposition periods during the late Middle-Late Pleistocene and Latest Pleistocene and intercalated episodes of palaeosol formation during the Late Pleistocene imply comparable climatic conditions across the SE Carpathians. Dominant strath-terraces of the eastern domain indicate stronger fluvial incision (~ 240 m) since the late Middle Pleistocene, whereas older strath- and younger dominant fill-terraces of the western domain designate a lower amount (~ 90 m) since the early Middle Pleistocene. Middle Pleistocene-Holocene fluvial incision rates document higher tectonic uplift in the external nappes and lower towards the western intramontane and eastern foredeep basins.

Necea, D.; Fielitz, W.; Kadereit, A.; Andriessen, P. A. M.; Dinu, C.

2013-08-01

233

Fluvial sediments a summary of source, transportation, deposition, and measurement of sediment discharge  

USGS Publications Warehouse

This paper presents a broad but undetailed picture of fluvial sediments in streams, reservoirs, and lakes and includes a discussion of the processes involved in the movement of sediment by flowing water. Sediment is fragmental material that originates from the chemical or physical disintegration of rocks. The disintegration products may have many different shapes and may range in size from large boulders to colloidal particles. In general, they retain about the same mineral composition as the parent rocks. Rock fragments become fluvial sediment when they are entrained in a stream of water. The entrainment may occur as sheet erosion from land surfaces, particularly for the fine particles, or as channel erosion after the surface runoff has accumulated in streams. Fluvial sediments move in streams as bedload (particles moving within a few particle diameters of the streambed) or as suspended sediment in the turbulent flow. The discharge of bedload varies with several factors, which may include particle size and a type of effective shear on the surface of the streambed. The discharge of suspended sediment depends partly on concentration of moving sediment near the streambed and hence on discharge of bedload. However, the concentration of fine sediment near the streambed varies widely, even for equal flows, and, therefore, the discharge of fine sediment normally cannot be computed theoretically. The discharge of suspended sediment also depends on velocity, turbulence, depth of flow, and fall velocity of the particles. In general, the coarse sediment transported by a stream moves intermittently and is discharged at a rate that depends on properties of the flow and of the sediment. If an ample supply of coarse sediment is available at the surface of the streambed, the discharge of the coarse sediment, such as sand, can be roughly computed from properties of the available sediment and of the flow. On the other hand, much of the fine sediment in a stream usually moves nearly continuously at about the velocity of the flow, and even low flows can transport large amounts of fine sediment. Hence, the discharge of fine sediments, being largely dependent on the availability of fine sediment upstream rather than on the properties of the sediment and of the flow at a cross section, can seldom be computed from properties, other than concentrations based directly on samples, that can be observed at the cross section. Sediment particles continually change their positions in the flow; some fall to the streambed, and others are removed from the bed. Sediment deposits form locally or over large areas if the volume rate at which particles settle to the bed exceeds the volume rate at which particles are removed from the bed. In general, large particles are deposited more readily than small particles, whether the point of deposition is behind a rock, on a flood plain, within a stream channel, or at the entrance to a reservoir, a lake, or the ocean. Most samplers used for sediment observations collect a water-sediment mixture from the water surface to within a few tenths of a foot of the streambed. They thus sample most of the suspended sediment, especially if the flow is deep or if the sediment is mostly fine; but they exclude the bedload and some of the suspended sediment in a layer near the streambed where the suspended-sediment concentrations are highest. Measured sediment discharges are usually based on concentrations that are averages of several individual sediment samples for a cross section. If enough average concentrations for a cross section have been determined, the measured sediment discharge can be computed by interpolating sediment concentrations between sampling times. If only occasional samples were collected, an average relation between sediment discharge and flow can be used with a flow-duration curve to compute roughly the average or the total sediment discharges for any periods of time for which the flow-duration c

Colby, B.R.

1963-01-01

234

Geomorphic response to agricultural land use in small fluvial systems - The role of landscape connectivity  

NASA Astrophysics Data System (ADS)

Nearly all river catchments are affected directly or indirectly by human actions, e.g. varying agricultural land use or interventions into to river course and flow lead to significant geomorphic changes. The rates of fluvial change are accelerating in many river catchments and public and institutional awareness of these changes and their consequences has grown. This trend leads to an increasing need for a deeper understanding of how the system elements are interrelated (connected) and how fluvial systems respond to human activities. Most of the studies relating to such topics focus on extrinsic (e.g. climatic) factors, although vegetation cover is one of the primary intrinsic factors on sediment yield to a river and even the most susceptible factor for human alterations. Furthermore, nearly all of the published studies are dealing with large rivers, disregarding the much more abundant smaller ones, which in sum do also influence larger rivers. The presented study contributes to gain a deeper understanding of how river systems geomorphologically respond to human activities. The focus in this study is on the importance of hillslope-channel connectivity relationships, as well as on connectivity relationships between the channel reaches in catchments with agricultural land use. Therefore, aerial photograph and airborne laserscan-interpretations were used to create detailed land use and river maps in order to gather current land use and river planform geometry conditions. The land use data was integrated to a GIS-related spatial soil erosion model so as to determine sources of fine sediment from eroding top soil in agricultural areas. Furthermore, a DEM-based multiple-flow model was applied to examine hillslope-channel connectivity relationships. River bed sediment composition, sediment embeddedness and in-channel accumulation of fine sediments were surveyed as potential indicators for geomorphic system response to agricultural land-use, as well as to determine connectivity relationships between the different channel reaches. The study area watersheds of the mixed-load rivers Fugnitz and Kaja are located in the Eastern part of the Bohemian Massif in Austria (Europe). These drainage basins can be morphologically subdivided into two units: The upper and middle reaches exhibit low river gradients, low slope angles (plateau character) and wide open valleys with sides flaring out. The lower reaches show high river gradients, high slope angles, V-shaped valleys, some of them with alluvial fills. In the upper and middle reaches, land-use is prevalently characterized by agriculture with only partially forested zones, whereas the lower reaches are dominated by forests and woodlands. This study area conditions allow comprehensive comparison of the connectivity between several system components. The results highlight that agricultural land use is a major driving factor in altering the sediment regime of fluvial systems, leading to bed sediment fining, especially in areas with high channel-hillslope connectivity. Converging to the lower reaches of the study areas, where minimum agricultural land-use is present, amounts of fine sediments are decreasing continuously because of sediment storage in pools or in the hyporheic zone.

Poeppl, R.; Keiler, M.; Glade, T.; Engage-Geomorphological Systems; Risk Research

2010-12-01

235

External controls on formation and preservation of fluvial terrace staircases in the Southern Pyrenees foreland  

NASA Astrophysics Data System (ADS)

The fluvial network of the Southern Pyrenees is an example of transverse drainage systems in young (alpine) mountain belts and it features well preserved fluvial terrace records. Some of the major Southern Pyrenees tributaries, like the Cinca and the Gallego, have been studied previously and have some age controls on their fluvial terrace levels. We extend these records to the largest drainage system of the Southern Pyrenees, the Segre river system, presenting new GIS and field data, as well as exposure ages obtained from in situ produced 10Be cosmogenic nuclides. The terrace staircase of the Segre River is built up by cut and fill type terraces, ranging from 112 to 3 meter above the present-day riverbed. Gravel deposits have commonly thicknesses of 2 to 7 meter over bedrock. Locally they have extensive thicknesses of up to 20 meter and show evidence for the impact of ongoing tectonics (i.e. gypsum doming, tectonic basin) featuring faults and folds as primary features. The terrace record can be subdivided into four groups of terraces that are separated by large incisive steps of about 20 meter: I) old extensive single terrace surfaces (TQ1, ~112m), II) terraces of limited extent preserved as remnant hills (TQ2, ~80m), III) two extensive terrace levels (TQ3 and TQ4, 60-45m), and IV) a well-preserved and extensive lower terrace complex (TQ5-TQ7, 30-3m). The staircase morphology (extent and elevations) of the Segre River shows analogies with other streams of the Southern Pyrenees indicating regional scale causes for the formation of terraces. The terraces TQ1, TQ2,TQ3 and TQ4 have been sampled for in situ produced 10Be cosmogenic nuclides. Our results show preliminary minimum ages of Middle to Late Pleistocene terrace abandonment: TQ1: 274 ka (MIS 9a), TQ2: 135 ka (MIS 5e), TQ3: 106 ka (MIS 5c), and TQ4: 65 ka (MIS 3), and erosion rates of 0.3 cm/ka (TQ1, TQ4), 0.45 cm/ka (TQ3), and 0.73 cm/ka for TQ2. The obtained ages indicate a causal relationship between terrace abandonment (incision) and interglacial periods, and point to a terrace formation (aggradation) related to glacial periods in the Pyrenean headwaters. Sedimentological outcrop observations corroborate a cold-climate based genesis of the terraces and present numerous braided channels, ice rafted boulders and frozen sand clasts. Morphologically, the extensive terraces surfaces point to a more than 4km wide presumably braided river system during formation of TQ1 and TQ2. The longitudinal terraces correlation reveals a downstream diverging trend along the lower reaches (foreland stretch) which is most likely base-level controlled. We link the divergence of the Segre terraces to the downcutting history of the Catalan Coastal Range that borders the Ebro foreland basin to the Mediterranean Sea. The stepped morphology with several topographic levels at the breach record the downcutting history of the Catalan Coastal Range. Our longitudinal Segre terrace profiles point to a base-level of about 200m a.s.l. at the begin of terrace formation at the Segre and indicate gradual incision since at least the Middle Pleistocene. We argue, that the Catalan Coastal Range functioned as a local base-level upstream the sea outlet presumably until the Late Pleistocene. Hence, the preservation of terrace staircases at the Southern Central Pyrenees does not require tectonic uplift (although it can not be excluded) and can be explained by base-level mechanisms, while the terrace formation is climate triggered and the result of glacial-interglacial-cycles in the Pyrenees.

Stange, K. M.; van Balen, R. T.; Carcaillet, J.

2012-04-01

236

Creating High Quality DEMs of Large Scale Fluvial Environments Using Structure-from-Motion  

NASA Astrophysics Data System (ADS)

During the past decade, advances in survey and sensor technology have generated new opportunities to investigate the structure and dynamics of fluvial systems. Key geomatic technologies include the Global Positioning System (GPS), digital photogrammetry, LiDAR, and terrestrial laser scanning (TLS). The application of such has resulted in a profound increase in the dimensionality of topographic surveys - from cross-sections to distributed 3d point clouds and digital elevation models (DEMs). Each of these technologies have been used successfully to derive high quality DEMs of fluvial environments; however, they often require specialized and expensive equipment, such as a TLS or large format camera, bespoke platforms such as survey aircraft, and consequently make data acquisition prohibitively expensive or highly labour intensive, thus restricting the extent and frequency of surveys. Recently, advances in computer vision and image analysis have led to development of a novel photogrammetric approach that is fully automated and suitable for use with simple compact (non-metric) cameras. In this paper, we evaluate a new photogrammetric method, Structure-from-Motion (SfM), and demonstrate how this can be used to generate DEMs of comparable quality to airborne LiDAR, using consumer grade cameras at low costs. Using the SfM software PhotoScan (version 0.8.5), high quality DEMs were produced for a 1.6 km reach and a 3.3 km reach of the braided Ahuriri River, New Zealand. Photographs used for DEM creation were acquired from a helicopter flying at 600 m and 800 m above ground level using a consumer grade 10.1mega-pixel, non-metric digital camera, resulting in object space resolution imagery of 0.12 m and 0.16 m respectively. Point clouds for the two study reaches were generated using 147 and 224 photographs respectively, and were extracted automatically in an arbitrary coordinate system; RTK-GPS located ground control points (GCPs) were used to define a 3d non-linear transformation to convert the point clouds to the absolute NZTM coordinate system, with average errors of 0.06 m in the horizontal and 0.11 m in the vertical dimensions. The final point clouds extracted had typical point spacings of 0.25 m, well above the metric resolution of airborne LiDAR. To improve data handling, the final point cloud was decimated to point spacings of 0.5 m using a recently developed gridding procedure (Rychkov, Brasington, & Vericat, 2012), and finally converted into a DEM using a Delaunay constrained TIN in ArcGIS. Results reveal SfM's ability to produce high quality terrain products of large scale fluvial environments that can outperform LiDAR, and can potentially compare with TLS. PhotoScan offers a straightforward method to generate, transform, and export DEMs that requires little user knowledge of photogrammetric processes. Further, the affordability and reduced field work offer low budget researchers the ability to produce repeat surveys for in-depth temporal studies. Funding supported by the New Zealand Department of Conservation.

Javernick, L. A.; Brasington, J.; Caruso, B. S.; Hicks, M.; Davies, T. R.

2012-12-01

237

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

NASA Astrophysics Data System (ADS)

Multiple evidences of soft-sediment to brittle deformation within the Pleistocene fluvial terraces of the Tagus, Jarama, Tajua 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, Tajua 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.

Silva, Pablo G.; Rodrguez Pascua, M. A.; Prez Lpez, R.; Giner Robles, J. L.; Roquero, E.; Tapias, F.; Lpez Recio, M.; Rus, I.; Morin, J.

2010-05-01

238

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

239

Late Holocene and present-day fluvial morphodynamics in small catchment areas of Central Germany  

NASA Astrophysics Data System (ADS)

During the past decades strong runoff events repeatedly occurred in small drainage basins of the European low mountains. In numerous events runoff was connected with erosion and transport of extensive bed load. Runoff events were predominantly triggered by rainstorms, which were limited to the catchment areas. They partly caused severe economic loss. The present study focuses on fluvial morphodynamics in northern Hesse and Lower Saxony. In this area runoff and transport of bed load occurred in small tributary catchment areas of the Fulda, Werra and Oberweser rivers. In general, the small drainage basins are used by agriculture and forestry. Drainage channels are developed as gullies and are incised into solid bedrock, Quaternary hillslope sediments, alluvial fills, and anthropogenic deposits. Vertical incision into the bedrock may amount to 1 meter per event. Furthermore, in single cases sediment discharge amounted to 16.000 m in addition to the suspension load. On the base of historical analyses about 50 severe runoff events with a maximum frequency of 10 events during 1965 are recorded during the past 150 years in the study area. Field survey, sedimentological analyses and dating reveal intensive runoff processes since the Neolithic age in a comparable catchment area. In this context potsherds could be dated to the Linear Pottery culture, which were detected in an alluvial cone of the "Rehgraben gully", close to the city of.Kassel. Furthermore, findings of fossil wood were recovered in the same alluvial cone. Radiocarbon dating reveals calibrated ages which are for the most parts younger than AD. In younger sediments we suppose the severe runoff event of 1342. Current studies in the catchment area of the Rehgraben aim to distinguish different processes of the fluvial morphodynamics on a temporal scale and to estimate potential Holocene erosional rates. References Damm, B., 2004. Geschiebe fhrende und murfhige Wildbche in Mittelgebirgsrumen. Interpraevent 10/3, Themenbereich VII Wildbach, 61-72. Dreibrodt, S., Lubos, C., Terhorst, B., Damm, B., Bork, H.-R., 2009. Historical Soil Erosion by Water in Germany. A Review. - Quaternary International, doi:10.1016/ j.quatint.2009.06.014. Kreikemeier, A., Damm, B., Bhner, J., Hagedorn, J., 2004. Wildbche im Fulda- und Oberwesereinzugsgebiet (Nordhessen und Sdniedersachsen) - Fallbeispiele und Anstze zur Abfluss- und Abtragsmodellierung. Zeitschrift fr Geomorphologie N.F., Suppl. Vol. 135, 69-94.

Englhard, Michael; Damm, Bodo; Frechen, Manfred; Terhorst, Birgit

2010-05-01

240

A Pleistocene coastal alluvial fan complex produced by Middle Pleistocene glacio-fluvial processes  

NASA Astrophysics Data System (ADS)

A coarse-grained alluvial fan sequence at Lipci, Kotor Bay, in western Montenegro, provides a sedimentary record of meltwater streams draining from the Orjen Massif (1,894 m a.s.l.) to the coastal zone. At Lipci sedimentary evidence and U-series ages have been used alongside offshore bathymetric imagery and seismic profiles to establish the size of the fan and constrain the nature and timing of its formation. Establishing the depositional history of such coastal fans is important for our understanding of cold stage sediment flux from glaciated uplands to the offshore zone, and for exploring the impact of sea level change on fan reworking. There is evidence of at least four phases of Pleistocene glaciation on the Orjen massif, which have been U-series dated and correlated to MIS 12, MIS 6, MIS 5d-2 and the Younger Dryas. A series of meltwater channels delivered large volumes of coarse- and fine-grained limestone sediment from the glaciated uplands into the Bay of Kotor. At the southern margin of the Orjen massif, a series of large (>700 m long) alluvial fans has developed. Some of these extend offshore for up to 600 m. Lipci fan lies downstream of end moraines in the valley immediately above, which were formed by an extensive outlet glacier of the Orjen ice cap during MIS 12. The terrestrial deposits are part of the fan apex (50 m a.s.l.) that lies at the foot of a steep bedrock channel, but the majority of the fan is now more than 25 m below sea level. The terrestrial fan sediments are strongly cemented by multiple generations of calcite precipitates: the oldest U-series ages are infinite indicating that the fan is >350 ka in age. These ages are in agreement with alluvial sedimentary evidence and U-series ages from other fluvial units on Mount Orjen. The terrestrial portion of the Lipci fan surface contains several channels. These are well preserved due to cementation with calcium carbonate. Submarine imagery indicates that the now submerged portion of the fan also contains deeply incised (up to 10 m) channels which are similar in morphology to those exposed onshore. It is likely that strong cementation of the fan sediments, and associated channel forms, has protected them from coastal erosion during several regression-transgression cycles. These records provide important opportunities to correlate the Pleistocene terrestrial glacial and fluvial records with the marine archive.

Adamson, Kathryn; Woodward, Jamie; Hughes, Philip; Giglio, Federico; Del Bianco, Fabrizio

2014-05-01

241

Meltwater pathways and grain size transformation in a Pleistocene Mediterranean glacial-fluvial system  

NASA Astrophysics Data System (ADS)

The Pleistocene sedimentary records of Mount Orjen, western Montenegro, have been used to investigate changes in grain size characteristics of fine sediments transported from the glaciated mountains to the fluvial systems downstream. Understanding the particle size characteristics of the fine sediments transported by these cold stage river systems is important for several reasons. The braided rivers draining the glaciated mountains of the western Balkans may have been an important source of loess for example. It is also important to establish the grain size signature of suspended sediment delivered to the marine environment to aid land-marine correlations. The fine-grained component of the tills is dominated by glacially-comminuted limestone particles. Detailed particle size analysis of the fine sediment matrix component (<63 ?m) of glacial till and alluvial deposits has been undertaken using multiple samples at 12 sites surrounding the Orjen massif. This limestone karst terrain includes a range of meltwater pathways and depositional contexts, including: river valleys, alluvial fans, poljes, and ice marginal settings. 35 U-series ages and soil development indices have been used to develop a robust geochronology for the Pleistocene records Two dominant surface meltwater and sediment pathways have been identified around Mount Orjen. The particle size distributions reveal that these transportation routes can have distinctive sedimentological signatures. Type 1 pathways deliver meltwater and sediments downstream via bedrock gorges. In these settings, the fine grained alluvial matrix presents a largely bimodal particle size distribution (PSD). Type 2 pathways represent meltwater channels draining directly from the ice margin. Alluvial sediments within these environments more closely resemble the normally distributed PSD of the glacial tills. The transition to bimodal PSDs, downstream of Type 1 meltwater routes, suggests that the glacially-comminuted sediments are modified in the fluvial environment. Significantly, the carbonate component is preferentially depleted or removed from the fine silt size fraction. Non-carbonate sediments are instead concentrated into this particle size window. This is thought to be a product of physical and chemical weathering as well as the mechanical sorting of glacially-derived limestone sediments. This has important implications for our understanding of sediment transfer processes within glaciated catchments before these sediments are transported offshore.

Adamson, Kathryn; Woodward, Jamie; Hughes, Philip

2013-04-01

242

The River Orontes in Syria and Turkey: Downstream variation of fluvial archives in different crustal blocks  

NASA Astrophysics Data System (ADS)

The geomorphology and Quaternary history of the River Orontes in western Syria and south-central Turkey have been studied using a combination of methods: field survey, differential GPS, satellite imagery, analysis of sediments to determine provenance, flow direction and fluvial environment, incorporation of evidence from fossils for both palaeoenvironments and biostratigraphy, uranium-series dating of calcrete cement, reconciliation of Palaeolithic archaeological contents, and uplift modelling based on terrace height distribution. The results underline the contrasting nature of different reaches of the Orontes, in part reflecting different crustal blocks, with different histories of landscape evolution. Upstream from Homs the Orontes has a system of calcreted terraces that form a staircase extending to ~200 m above the river. New U-series dating provides an age constraint within the lower part of the sequence that suggests underestimation of terrace ages in previous reviews. This upper valley is separated from another terraced reach, in the Middle Orontes, by a gorge cut through the Late Miocene-Early Pliocene Homs Basalt. The Middle Orontes terraces have long been recognized as a source of mammalian fossils and Palaeolithic artefacts, particularly from Latamneh, near the downstream end of the reach. This terraced section of the valley ends at a fault scarp, marking the edge of the subsiding Ghab Basin (a segment of the Dead Sea Fault Zone), which has been filled to a depth of ~ 1 km by dominantly lacustrine sediments of Pliocene-Quaternary age. Review of the fauna from Latamneh suggests that its age is 1.2-0.9 Ma, significantly older than previously supposed, and commensurate with less uplift in this reach than both the Upper and Lower Orontes. Two localities near the downstream end of the Ghab have provided molluscan and ostracod assemblages that record somewhat saline environments, perhaps caused by desiccation within the former lacustrine basin, although they include fluvial elements. The Ghab is separated from another subsiding and formerly lacustrine depocentre, the Amik Basin of Hatay Province, Turkey, by a second gorge, implicit of uplift, this time cut through Palaeogene limestone. The NE-SW oriented lowermost reach of the Orontes is again terraced, with a third and most dramatic gorge through the northern edge of the Ziyaret Da?? mountains, which are known to have experienced rapid uplift, probably again enhanced by movement on an active fault. Indeed, a conclusion of the research, in which these various reaches are compared, is that the crust in the Hatay region is significantly more dynamic than that further upstream, where uplift has been less rapid and less continuous.

Bridgland, David R.; Westaway, Rob; Romieh, Mohammad Abou; Candy, Ian; Daoud, Mohamad; Demir, Tuncer; Galiatsatos, Nikolaos; Schreve, Danielle C.; Seyrek, Ali; Shaw, Andrew D.; White, Tom S.; Whittaker, John

2012-09-01

243

Exploring controls on valley spacing in higher order fluvial channels with the CHILD Model  

NASA Astrophysics Data System (ADS)

Across a wide range of landscapes the ratio between the width of a mountain and the distance separating trunk channels exiting the mountain front (generally termed the valley spacing ratio) has been observed to be fairly constant, but the reasons for its uniformity are not well understood. Recent work also suggests that the ratio between the spacing of valleys and the characteristic length, or distance from the divide to where hillslopes transition to fluvial channels, (here termed the characteristic length ratio) is relatively constant in first order channels. We propose that the characteristic length ratio of higher order channels is a primary control on the valley spacing ratio. We explore how these ratios are linked together and the variables that may affect both of these ratios using the CHILD numerical landscape evolution model. Previous studies observed a linear relationship between valley spacing and characteristic length in first order channels, and we find that the relationship remains linear in higher order channels, demonstrating that the competition between hillslope and fluvial processes influences landscape morphology at all scales. Moreover, we also find that the characteristic length ratio for a given order channel is fairly robust and does not appear to be impacted by model initial conditions (such as initial topography) and precipitation patterns (such as orographic precipitation). For a fixed domain in our model, although the characteristic length may vary, the valley spacing ratio remains in the range observed in real landscapes. The ratio of mountain width to valley spacing remains relatively constant because the order of trunk channels varies with the characteristic length. In other words, for a given domain size (or mountain range width), a larger characteristic length can produce lower order trunk channels but with the same spacing value as higher order trunk channels with a smaller characteristic length. This competition between channel order and characteristic length may be one of the reasons why the valley spacing ratio is relatively constant across diverse natural settings. However, our model results also show that initial and boundary conditions may affect the maximum stream order in a domain, even though they do not affect valley spacing. As a result, the valley spacing ratio is more variable than the characteristic length ratio. For example, we find that more pronounced orographic precipitation patterns, or much steeper initial surfaces, can lead to more linear streams, less tributary branching and lower order trunk channels. In this case, the ratio between valley spacing and characteristic length remains the same, whereas the ratio between mountain width and valley spacing increases, but still remains within the observed range in natural landscapes. Finally, DEM analysis of three study areas supports our numerical results.

Han, J.; Gasparini, N. M.; Johnson, J. P.

2013-12-01

244

A Survey of Sinuous Ridges and Inferred Fluvial Discharge Rates in Northwest Hellas, Mars  

NASA Astrophysics Data System (ADS)

Sinuous ridges are a widespread class of geomorphic feature on Mars, and in many cases are interpreted to be inverted fluvial channels. Although negative-relief valley networks thought to be related to fluvial activity have been mapped in detail over the entire planet (e.g. Carr, 1995; Hynek et al., 2010), few regional- to global-scale surveys of sinuous ridges have been conducted (e.g. Williams, 2007; Jacobsen and Burr, 2012). With the availability of Context Camera (CTX ) images from the Mars Reconnaissance Orbiter (MRO) covering a significant fraction of the martian surface at 6 meters per pixel, such studies are now feasible. In addition, Williams et al. (2009) have demonstrated that paleodischarge can be calculated based on the width, meander wavelength, and meander radius of sinuous ridges interpreted to be inverted channels. This method has been used successfully on the sinuous ridges in the Aeolis/Zephyria plana region (Burr et al., 2010). We have begun a survey of sinuous ridges in the northwest Hellas region (-15 N to -45 N, 30 E to 75 E) using 1156 radiometrically calibrated and map projected CTX images. This region includes the northwestern portion of the Hellas basin floor and rim, as well as a significant expanse of the cratered highlands to the north and west of the basin. This region was chosen because it includes terrain of varying age (primarily Noachian to Hesperian; Leonard and Tanaka, 2001) and includes "raised curvilinear features" identified by Williams (2007) on the western basin floor, northern rim, and in the highlands northwest of Hellas . By mapping the distribution of sinuous ridges in terrain of varying age and estimating their paleodischarge rates, we will be able to determine how the discharge rate varied over martian history. Carr, M. H. (1995), J. Geophys. Res., 100, 7479-7507, doi:10.1029/95JE00260. Hynek, B. M., M. Beach, and M. R. T. Hoke (2010), J. Geophys. Res., 115, E09008, doi:10.1029/2009JE003548. Williams, R.M.E. (2007), LPSC XXXVIII, Abstract #1821 Jacobsen, R.E. and Burr, D.M., (2012), LPSC XLIII, Abstract #2398 Williams, R.M.E., Irwin III, R.P., Zimbelman, J.R. (2009), Geomorphology 107, p.300-315. Burr, D. M., et al. (2010), J. Geophys. Res., 115, E07011, doi:10.1029/2009JE003496. Leonard, G.J. and Tanaka, K.L. (2001) USGS Geologic Investigations Series I-2694.

Anderson, R. B.; Herkenhoff, K. E.

2012-12-01

245

Distinguishing Long-Term Controls on Fluvial Architecture in the Lance Formation, Bighorn Basin, Wyoming  

NASA Astrophysics Data System (ADS)

Allogenic processes are considered a prime control on the stratigraphic distribution of channel bodies, however, recent studies have indicated that autogenic stratigraphic organization may occur within fluvial systems on basin- filling time scales (105-106 years). Groupings or clusters of closely-spaced channel bodies can be produced by several different mechanisms, including both allogenic and autogenic processes. Commonly, sand- dominated intervals in stratigraphic successions are interpreted as incised-valley fills produced by base-level changes. In contrast, long-timescale organization of river avulsion can generate similar stratigraphic patterns. For example, sand-dominated intervals in the fluvial Lance Formation (Maastrichtian; Bighorn Basin, WY) have been interpreted as incised-valley fills formed during sea-level lowstand. However, closely-spaced sand bodies in the Ferris Formation (Lance equivalent; Hanna Basin, WY) are interpreted as aggradational in origin, and have been compared to autogenic avulsion stratigraphy produced in experimental basins. We evaluate the Lance Formation in the southern Bighorn Basin in an effort to determine whether these sand-dominated intervals are truly incised- valley fills resulting from sea-level changes, or if they were generated by autogenic processes. The Lance Formation crops out in the western and southern margins of the basin, exposing relatively proximal and distal portions of the system. By comparing alluvial architecture between exposures, we evaluate similarities and differences from upstream to downstream and look for evidence of intrinsic and extrinsic controls on deposition. In both localities, the Lance Formation comprises multi-story sheet sandstones and smaller, single-story sandstones. Observed changes from upstream to downstream in the system include: 1) increasing paleoflow depths (from ~30-60 cm to ~70-120 cm); 2) decreasing preservation of fine-grained material within channel bodies; 3) increasing proportion of amalgamated, multi-story sand bodies; and 4) increasing lateral continuity of multi-story sand bodies. These results indicate that upstream, channel-body spacing is dominantly controlled by aggradational processes and may be the result of autogenic avulsion clustering, whereas downstream, evidence of incision and amalgamation indicate that base-level may have limited and controlled sand-body architecture.

McHarge, J. L.; Hajek, E. A.; Heller, P. L.

2007-12-01

246

Rate of fluvial incision in the Central Alps constrained through joint inversion of detrital 10Be and thermochronometric data  

NASA Astrophysics Data System (ADS)

We integrate constraints from published detrital thermochronometry and detrital 10Be concentrations in a single catchment to infer how erosion is shaping Alpine topography. We apply this analysis to the Codera watershed in the Bergell Intrusion, Central European Alps, where rivers have incised into a glacial valley. Because thermochronometric ages of bedrock samples increase with elevation, a distribution of detrital ages in river sediment provides a tracer for the source elevations of sediment within the catchment, while detrital 10Be concentrations provide constraints on rates of erosion. We find that modern erosion rates within the fluvial portion of the landscape are too low to permit the inferred ?500 m of incision during the most recent interglacial. Based on the spatial pattern of modern erosion rates, we predict that if the incised fluvial valley was formed during interglacial periods only, it has formed over the last approximately 400,000 years.

Fox, Matthew; Leith, Kerry; Bodin, Thomas; Balco, Greg; Shuster, David L.

2015-02-01

247

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

Microsoft Academic Search

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

Isbell

1990-01-01

248

Impact of the deeper geological basement on soil gas and indoor radon concentrations in areas of Quaternary fluvial sediments (Bohemian Massif, Czech Republic)  

Microsoft Academic Search

The relationship of soil gas radon Rn222 and indoor radon was studied within the Quaternary fluvial sediments of the Czech Republic. The processing of data selection\\u000a from the radon database of the Czech Geological Survey and indoor radon data (database of the National Radiation Protection\\u000a institute) has proved the concentration dependence of radon in Quaternary fluvial sediments on deeper bedrock.

Ivan BarnetPetra; Petra Pacherov

2011-01-01

249

Non-marine successions in the northwestern part of Kyongsang Basin (Early Cretaceous): Fluvial styles and stratigraphic architecture  

Microsoft Academic Search

Non-marine successions in the northwestern part of Kyongsang Basin (Early Cretaceous) are divided into successive stratigraphic\\u000a units based on facies assemblages and architecture of sandstone bodies. In the present study, two stratigraphic units (Sinpyong-Anpyong\\u000a and Jotap units) are documented in detail in terms of fluvial architecture. The Sinpyong-Anpyong unit is divided into thick\\u000a sandstone, thin sandstone, and mudstone-dominated bodies, representing

Hyung Rae Jo

2003-01-01

250

Blue Spur Conglomerate: Auriferous Late Cretaceous fluvial channel deposits adjacent to normal fault scarps, southeast Otago, New Zealand  

Microsoft Academic Search

Latest Cretaceous Blue Spur Conglomerate at Gabriels Gully was deposited in a northeast?southwest?trending valley incised >200 m into metamorphic basement within the Tuapeka Fault Zone. Clast imbrication unequivocally indicates paleoflow towards the southwest, across the Tuapeka Fault Zone from the uplifted block. Early schist?and quartz?rich fluvial sediments in the valley and transverse mass flow deposits derived from the valley sides

B. G. Els; J. H. Youngson; D. Craw

2003-01-01

251

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

E-print Network

THREE-DIMENSIONAL FLUVIAL-DELTAIC SEQUENCE STRATIGRAPHY PLIOCENE-RECENT MUDA FORMATION, BELIDA FIELD, WEST NATUNA BASIN, INDONESIA A Thesis by YAN DARMADI Submitted to the Office of Graduate Studies of Texas A&M University..., WEST NATUNA BASIN, INDONESIA A Thesis by YAN DARMADI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair...

Darmadi, Yan

2007-04-25

252

Pebble abrasion during fluvial transport: Experimental results and implications for the evolution of the sediment load along rivers  

E-print Network

of the sediment load along rivers Mikae¨l Attal1 and Je´ro^me Lave´2 Received 30 March 2009; revised 18 August, fluvial abrasion modifies the characteristics of the sediment carried by rivers and consequently has for the evolution of the sediment load along rivers, J. Geophys. Res., 114, F04023, doi:10.1029/2009JF001328. 1

253

Environmental magnetic record of the fluvial sediments from the Tianzhu borehole in Beijing for the last 800 ka  

Microsoft Academic Search

A high-resolution environmental magnetic investigation has been carried out on a 186.3-m-thick sequence of fluvial sediments from the Tianzhu borehole in the Beijing Plain. Magnetic stratigraphic analysis revealed that the sediment sequence spans the last 800 ka without significant hiatuses. Comparison of the magnetic susceptibility (k) with pollen records suggests that the magnetic susceptibility serves as a good proxy for

L. Shi; Z. Yang; L. Zheng; S. Jia; Y. Tong; S. Zhang; D. Xu; G. Guo

2010-01-01

254

Depositional environment of Hosston sandstones (lower cretaceous), Bogalusa Field, Washington Parish, Louisiana (identification of deltaic and fluvial sequences in logs)  

E-print Network

DEPOSITIONAL ENVIRONMENT OF HOSSTON SANDSTONES (LOWER CRETACEOUS), BOGALUSA FIELD, WASHINGTON PARISH, LOUISIANA (IDENTIFICATION OF DELTAIC AND FLUVIAL SEQUENCES IN LOGS) A thesis by CATHERINE COX STRONG Submitted to the Graduate College... of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May 1983 Major Subject: Geology DEPOSITIONAL ENVIRONMENT OF HOSSTON SANDSTONES (LOWER CRETACEOUS), BOGALUSA FIELD, WASHINGTON PARISH, LOUISIANA...

Strong, Catherine Cox

2012-06-07

255

Fluvial processes in Ma'adim Vallis and the potential of Gusev crater as a high priority site  

NASA Technical Reports Server (NTRS)

According to exobiology site selection criteria for Mars, the search for potential extinct/extant water dependent life should focus on sites were water flowed and ponded. The Ma'adim Vallis/Gusev crater system is of high priority for exobiology research, because it appears to have involved long term flooding, different periods and rates of sedimentation, and probable episodic ponding. The topics covered include the following: evidence of nonuniform fluvial processes and early overflooding of the plateau and ponding.

Cabrol, Nathalie; Landheim, Ragnild; Greeley, Ronald; Farmer, Jack

1994-01-01

256

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

Microsoft Academic Search

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 20.0C. Thermal tolerances increased with acclimation temperatures; mean CTM was 26.4C for the 8.4C acclimation group, 28.5C for the 16.0C group, and 29.3C

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

1996-01-01

257

Toward the Validation of Depth-Averaged Three Dimensional, Rans Steady-State Simulations of Fluvial Flows at Natural Scale  

Microsoft Academic Search

Simulations of fluvial flows are strongly influenced by geometric complexity and overall uncertainty on measured flow variables, including those assumed to be well known boundary conditions. Often, 2D steady-state models are used for computational simulations of flows at the scale of natural rivers. Such models have been successfully incorporated in iRIC (formerly MD_SWMS), one of the widely used quasi-3D CFD

P. A. Mateo Villanueva; M. Hradisky

2010-01-01

258

Depositional mechanisms controlling formation of coarse fluvial conglomerates in the lower triassic continental red beds of middle europe  

Microsoft Academic Search

Coarse fluvial conglomerates containing numerous cobbles and boulders occur in various formations within the Lower Triassic continental red beds of Middle Europe. The rudites mainly originate as longitudinal gravel bars in highly-braided river systems with narrowly-spaced and straight to slightly sinuous channels. The high-energy stream sedimentation and the frequent and rapid lateral shifting of the watercourses control origin, distribution and

Detlef Mader

259

Deciphering the Late Quaternary fluvial dynamics at the foothill of an active orogen - the example of the Transcaucasian depression in eastern Georgia  

NASA Astrophysics Data System (ADS)

Generally, the dynamics of fluvial systems can be triggered by climate, tectonics, anthropogenic activity or internal mechanisms. The lowland of the Transcaucasian depression is located between the Greater Caucasus in the north and the Lesser Caucasus in the south. Both mountainous massifs form a part of the Alpidic orogenic belt and are thus characterized by a high tectonic activity. During the Weichselian glaciation, due to their altitude >3000 m the massifs were strongly glaciated. During the last years, we investigated fluvial sediment sequences of several rivers that originate from the mountain belts and cross the eastern semi-arid part of the Transcauscasian depression towards the Caspian Sea (e.g. Algeti, Khrami, Kura, Alazani), in order to decipher changes of their fluvial dynamics during the past. The investigated sediments of Late Pleistocene and Holocene age show thicknesses up to 50 m and are mostly well outcropped. Our morphologic, sedimentologic and chronostratigraphic investigations of different sediment sequences demonstrate distinctive changes of the fluvial dynamics between the Late Pleistocene and the Holocene, and show that high-frequent Holocene changes of the fluvial pattern of the rivers are probably linked to climatic and/or anthropogenic triggers. Additionally, on a longer time scale the fluvial dynamics of the rivers is obviously controlled by ongoing tectonic processes.

von Suchodoletz, Hans; Faust, Dominik

2013-04-01

260

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

USGS Publications Warehouse

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.

Hupp, C.R.; Rinaldi, M.

2007-01-01

261

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

PubMed

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

Peterson, Joseph E; Coenen, Jason J; Noto, Christopher R

2014-01-01

262

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

PubMed Central

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

Coenen, Jason J.; Noto, Christopher R.

2014-01-01

263

Control of soil acidification by fluvial sedimentation in an estuarine floodplain, eastern Australia  

NASA Astrophysics Data System (ADS)

A shallow stratigraphic sequence with associated pyrite-induced soil acidification was investigated along a transect from the levee to the backswamp in an estuarine floodplain of eastern Australia. Three sedimentary layers were identified and interpreted to correspond with three depositional stages. Firstly, a layer of humic, pyrite-rich, silty mud was deposited under a saline, mangrove-inhabited, intertidal environment during the present high sea level episode. This pyritic layer is buried by the second sedimentary layer of grey brown mud with limited pyrite content, that was deposited in a brackish lagoonal environment. This material now represents much of the contemporary backswamp surface. The third sedimentary layer is a sandy mud without pyrite, that has been deposited by freshwater overbank floods. It is concluded that fluvial sedimentation has been increasingly important in the development of the stratigraphic sequence, controlling the pyrite content, thickness and occurrence depth of the pyritic layer. The present drainage conditions have allowed oxidation of pyrite in the soils of the backswamp and the resulting acidification has caused elevated concentrations of toxic aluminium that threaten the local environment. However, in the levee, the pyritic layer is covered by thick non-pyritic freshwater sediments and low-pyritic lagoonal sediments, and the soil profiles are unlikely to contribute to any acidification hazard.

Lin, C.; Melville, M. D.

1993-05-01

264

Ice jam-caused fluvial gullies and scour holes on northern river flood plains  

NASA Astrophysics Data System (ADS)

Two anomalous fluvial landforms, gullies and scour holes, eroded into flood plains bordering meandering and braiding river channels have not been previously reported. We observed these features along the Milk River in southern Alberta, Canada, and northern Montana, USA, which has a history of frequent (50% probability of recurrence) and high-magnitude (12% probability of recurrence greater than bankfull) ice jam floods. Gullies have palmate and narrow linear shapes with open-ends downvalley and measure up to 208 m long139 m wide3.5 m deep (below bankfull). Channel ice jams reroute river water across meander lobes and cause headward gully erosion where flow returns to the main channel. Erosion of the most recent gully was observed during the record 1996 ice breakup flood and ice jams. Scour holes (bowl-shaped, closed depressions), eroded by water vortices beneath and between grounded ice jam blocks, measure up to 91 m long22 m wide4.5 m deep. Ice jam-caused gullies may be precursors to the formation of U-shaped oxbow lakes and multiple channels, common in many northern rivers.

Smith, Derald G.; Pearce, Cheryl M.

2002-01-01

265

Sensitivity of fluvial sediment source apportionment to mixing model assumptions: A Bayesian model comparison  

NASA Astrophysics Data System (ADS)

models have become increasingly common tools for apportioning fluvial sediment load to various sediment sources across catchments using a wide variety of Bayesian and frequentist modeling approaches. In this study, we demonstrate how different model setups can impact upon resulting source apportionment estimates in a Bayesian framework via a one-factor-at-a-time (OFAT) sensitivity analysis. We formulate 13 versions of a mixing model, each with different error assumptions and model structural choices, and apply them to sediment geochemistry data from the River Blackwater, Norfolk, UK, to apportion suspended particulate matter (SPM) contributions from three sources (arable topsoils, road verges, and subsurface material) under base flow conditions between August 2012 and August 2013. Whilst all 13 models estimate subsurface sources to be the largest contributor of SPM (median 76%), comparison of apportionment estimates reveal varying degrees of sensitivity to changing priors, inclusion of covariance terms, incorporation of time-variant distributions, and methods of proportion characterization. We also demonstrate differences in apportionment results between a full and an empirical Bayesian setup, and between a Bayesian and a frequentist optimization approach. This OFAT sensitivity analysis reveals that mixing model structural choices and error assumptions can significantly impact upon sediment source apportionment results, with estimated median contributions in this study varying by up to 21% between model versions. Users of mixing models are therefore strongly advised to carefully consider and justify their choice of model structure prior to conducting sediment source apportionment investigations.

Cooper, Richard J.; Krueger, Tobias; Hiscock, Kevin M.; Rawlins, Barry G.

2014-11-01

266

Single and mixture effects of pesticides and a degradation product on fluvial biofilms.  

PubMed

The Morcille River located in the Beaujolais vineyard area (Eastern France) is subjected to strong vine-growing pressure leading to the contamination by a range of herbicides and fungicides of the surrounding freshwater environment. Particularly high concentrations of norflurazon, desmethyl norflurazon and tebuconazole were recorded in spring 2010 at the downstream site of the river. Despite their occurrence in rivers, scarce toxicity data are available for these products, in particular in the case of desmethyl norflurazon (main norflurazon degradation product). Furthermore, the toxicity data are generally available only for single compounds and are issued from single species toxicity tests, leading to a lack of ecological relevance. Consequently, this study was undertaken to evaluate the toxic effects of norflurazon, desmethyl norflurazon and tebuconazole singly and in a ternary mixture on fluvial biofilm. Toxicity tests were performed in microplates for 48 h. Photosynthetic endpoints were measured using pulse amplitude-modulated fluorometry; diatom densities and taxonomic composition were determined. After 48 h of exposure, significant effects on optimal quantum yield (F v/F m) for desmethyl norflurazon and mixture were observed. PMID:24549942

Tiam, Sandra Kim; Libert, Xavier; Morin, Soizic; Gonzalez, Patrice; Feurtet-Mazel, Agns; Mazzella, Nicolas

2014-06-01

267

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

268

Three-dimensional reconstruction of an evolving fluvial system: Chinle Formation, northeastern Arizona  

SciTech Connect

Exceptional three-dimensional (3-D) exposures of the Triassic Chinle Formation in northeastern Arizona allow detailed architectural analyses of a complex fluvial system. Lateral profiling, element analysis , and hierarchy of bounding surfaces demonstrate deposition in both low- and high-sinuosity channel systems. Two conglomerate bodies, the Shinarump and the Sonsela, were deposited in low-sinuosity, valley-confined systems as indicated by internal sequences of sedimentary structures and geometry of the macroforms. Stacked channel sequences consist of in-channel sandy bed forms separated from large, in-channel, downstream-accreting sandy macroforms (up to 5 m thick by 50 m long) bounded by fourth-order surfaces. Within localized channels, conglomerate bar complexes (up to 10 m thick by 150 m long) record downstream and oblique accreting macroforms bound both laterally and vertically by in-channel elements. Architectural features in the Chinle reflect intrabasinal as well as extrabasinal controls on sedimentation. Major changes in stream sinuosity are largely controlled by gradient changes associated with increased subsidence rates with time.

Deacon, M.W.; Middleton, L.T.

1989-03-01

269

Geologie study off gravels of the Agua Fria River, Phoenix, AZ  

USGS Publications Warehouse

The annual consumption of sand and gravel aggregate in 2006 in the Phoenix, AZ metropolitan area was about 76 Mt (84 million st) (USGS, 2009), or about 18 t (20 st) per capita. Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix are mined and processed to provide some of this aggregate to the greater Phoenix area. The Agua Fria drainage basin (Fig. 1) is characterized by rugged mountains with high elevations and steep stream gradients in the north, and by broad alluvial filled basins separated by elongated faultblock mountain ranges in the south. The Agua Fria River, the basins main drainage, flows south from Prescott, AZ and west of Phoenix to the Gila River. The Waddel Dam impounds Lake Pleasant and greatly limits the flow of the Agua Fria River south of the lake. The southern portion of the watershed, south of Lake Pleasant, opens out into a broad valley where the river flows through urban and agricultural lands to its confluence with the Gila River, a tributary of the Colorado River.

Langer, W.H.; Dewitt, E.; Adams, D.T.; O'Briens, T.

2010-01-01

270

Variable responses of fluvial systems to late Quaternary climate changes in NW Romania  

NASA Astrophysics Data System (ADS)

In this paper, we discuss the similarities and differences in timing and style of fluvial processes (incision, terrace detachment, changes in the sedimentation styles) manifestation for different reference moments during the Late Quaternary history of two neighboring, medium size rivers from the NW part of Transylvanian Depression (Some?ul Mic River, 175 km long, drainage surface of 3773 kmp, and Arie? River, 167 km long, drainage surface of 2970 kmp). In the case of Somesul Mic River, a shallow, coarse gravel, braided channel was active at the level of the first terrace (T1, 5-8 m relative altitude), at least as early as MIS 3. After incision and formation of the present valley bottom, a low energetic river was active (,meandering or anabranching), which was later replaced by a shallow, coarse gravel braided channel (similar with the one on TI), active before LGM and maintained untill the Younger Dryas (or the early Holocene). During the early Holocene, the braided channel was replaced by a transitional one, slightly incised in the previous phase's alluvial materials, further abandoned for an incised, narrow meandering channel. The last channel type change is probably related to the large scale arrival and development of deciduous trees species in the area (~10.x kyrs BP), implying a few hundred years delay of the final fluvial adjustment to the new temperate conditions associated to the YD/Holocene transition. Along Aries River, a comparative shallow, coarse gravel, braided river was active at the level of TI, during MIS 3. However, erosional features on the top of the gravel sheet and some palaeomeanders are visible on the terrace surface, and suggest the existence of a transitional / meandering channel before this surface was completely abandoned. In the floodplain perimeter, an absolute age of the upper part of the coarse gravel sediments suggests this river style was functional at least during LGM, possibly earlier. This age, and the morphological and sedimentological evidences for generations of palaeomeanders imposed erosivelly on the upper part of the sedimentary sequence, suggest a meandering pattern probably starting with the Bolling - Allerod Interstadial. The results show that two very similar rivers, in terms of their location and present-day morphometric characteristics, do have similar large reactions to Late Quaternary climate changes, however, significant differences can be found in details of reaction time and the involved processes. The existing data suggest that Aries River is a more sensitive one than Somesul Mic River. The more conservatory behavior in the last case (e.g., no channel change during the Bolling - Allerod Interstadial, delayed reaction in the early Holocene) is probably explained by the slightly higher slope of this particular river, related to the presence of a large scale knickpoint in the medium part of the longitudinal profile (ca. 380 m), imposed by local geological conditions.

Per?oiu, Ioana; Per?oiu, Aurel

2014-05-01

271

Stratigraphic evidence of past fluvial activity in southern Melas Chasma, Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

During the late Noachian and early Hesperian periods, listric faulting led to the development of a series of hanging depressions throughout the Valles Marineris canyon system [1]. One such depression, situated on the southern wall of Melas Chasma, forms an enclosed basin which has since undergone modification from the late Hesperian to Amazonian. There is a multitude of evidence suggesting that the basin (hereon in referred to as the Southern Melas Chasma Basin; SMCB) was once host to active fluvial processes, that at minimum lasted for several hundred years [2,3]. Central to this is what appears to be the remains of a palaeolake, which is approximately 80 by 40 kilometres in area. The palaeolake contains a complex sequence of sedimentary stratigraphy, which includes several structures that resemble deltas and/or submarine fans on both the east and west side of the basin [4], and appear to originate from a network of channels and valleys that terminate in the basin. Previous studies have shown that the western valley network has drainage densities similar to terrestrial values and a dendritic nature that is indicative of precipitation and surface runoff [3]. Higher resolution mapping of the SMCB is important to further understand the stratigraphic succession and geomorphology, and to quantify how long liquid water may have been present within the basin. For this study, new digital elevation models (DEMs) have been produced in SOCET SET using stereo images from the Context Camera (CTX) and the High Resolution Imaging Science Experiment (HiRISE), both aboard the Mars Reconnaissance Orbiter. The DEMs have been produced at ~6 and ~1 m/pixel vertical resolution for CTX and HiRISE respectively. There is approximately 150-200 m of sediment within the stratigraphic succession; some individual strata are less than 10 m thick. The delta/fan structures appear to occur at different stratigraphic positions low down within the sequence. Clinoform-like and cross-bedded structures are shown to occur near the top of the sequence (a contrast to the laterally expansive, planar beds below), which suggest a significant change in depositional conditions within the SMCB during the time liquid water was stable. References: 1. Andrews-Hanna, J. C. The formation of Valles Marineris: 3. Trough formation through super-isostasy, stress, sedimentation, and subsidence. J. Geophys. Res. 117, E06002 (2012). 2. Mangold, N., Quantin, C., Ansan, V., Delacourt, C. & Allemand, P. Evidence for precipitation on Mars from dendritic valleys in the Valles Marineris area. Science 305, 78-81 (2004). 3. Quantin, C. Fluvial and lacustrine activity on layered deposits in Melas Chasma, Valles Marineris, Mars. J. Geophys. Res. 110, E12S19 (2005). 4. Metz, J. M. et al. Sublacustrine depositional fans in southwest Melas Chasma. J. Geophys. Res. 114, E10002 (2009).

Davis, Joel; Grindrod, Peter

2014-05-01

272

Provenance of the Fluvial-deltaic Sedimentary Deposits Within the Eberswalde Crater Catchment, Mars  

NASA Astrophysics Data System (ADS)

Eberswalde crater is one of few locations on Mars where a clear source-to-sink sedimentary path can be identified [1]. While the delta in western Eberswalde crater has been extensively studied [e.g., 2-5], few studies have described the catchment geology. [e.g. 6-7]. Here we present a geologic and compositional study of the catchment in order to characterise the source region for the Eberswalde delta. We have used DTMs and images from MRO's Context Camera (CTX) to map the channels that feed the delta at a finer scale than has previously been possible and to identify the headwater regions. We find that all channels begin on local or regional topographic highs, suggesting precipitation or snowmelt as a source of water rather than mobilization of subsurface ice due to hot overlying ejecta from the Holden crater impact [6]. Comparisons of channel depth and estimated Holden crater ejecta thickness throughout the catchment, in addition to our geologic mapping, indicate that the source for the Eberswalde sediments is almost exclusively Holden crater ejecta. One exception is the northern catchment area where channel depths exceed Holden ejecta thicknesses and therefore likely sample underlying Eberswalde ejecta or Holden basin rim material. Previous studies have confirmed the presence of Fe-Mg phyllosilicates in both the Holden crater walls [8] and ejecta [1]. We have also identified Fe-Mg phyllosilicates in a sedimentary deposit in a local basin within the Eberswalde catchment which has been eroded by the main Eberswalde fluvial system [9]. Therefore, there are phyllosilicates within the source sediments for the main deltaic feature within Eberswalde crater. However, some of the channels erode into Noachian-age Eberswalde ejecta and possibly the Holden basin rim. [9-11] have identified a subsurface layer of phyllosilicates that is present throughout the plateau region south of Vallis Marineris, west of Holden and Eberswalde craters, and north of Nirgal Vallis. This layer may have been sampled by the Eberswalde and Holden crater impacts [9]. Lastly, [12] have identified sedimentary phyllosilicate deposits throughout the Noachian-age Ladon basin and it is likely that phyllosilicates are also present in Holden basin sediments. Therefore, we have identified a clear source-to-sink for fluvially-transported phyllosilicate-bearing materials in the Eberswalde system. [1] Milliken, R. E. and D. L. Bish., 2010, JGR, 90, 17-18, 2293; [2] Lewis, K. W. and O. Aharonson., 2006, JGR, 111, E06001; [3] Wood, L. J., 2006, GSA Bulletin, 118, 5/6, 557; [4] Pondrelli, M., et al., 2008, Icarus, 197, 429; [5] Rice, M. S., et al., 2013, MARS, 8, 15-59; [6] Mangold, N., et al., 2012, Icarus, 220, 530-551; [7] Irwin III, R. P., 2011, LPSC XLII, abstract# 2748; [8] Grant, J. A. et al., 2008, Geology, 36, 3, 195-198; [9] McKeown et al., 2013, LPSC XLIV, abstract# 2302; [10] Le Deit, L. et al., 2012, JGR, 117, E00J05; [11] Buczkowski, D. L. and Seelos, K. D., 2010, MSL Landing Site Workshop; [12] Weitz et al., 2013, LPSC XLIV, abstract# 2081

McKeown, N.; Warner, N. H.; Rice, M. S.; Grindrod, P. M.

2013-12-01

273

Complex fluid flow revealed by monitoring CO2 injection in a fluvial formation  

NASA Astrophysics Data System (ADS)

At Cranfield, Mississippi, United States, a large-scale carbon dioxide (CO2) injection through an injection well (3,080 m deep) was continuously monitored using U-tube samplers in two observation wells located 68 and 112 m east of the injector. The Lower Tuscaloosa Formation injection zone, which consists of amalgamated fluvial point-bar and channel-fill deposits, presents an interesting environment for studying fluid flow in heterogeneous formations. Continual fluid sampling was carried out during the first month of CO2 injection. Two subsequent tracer tests using sulfur hexafluoride (SF6) and krypton were conducted at different injection rates to measure flow velocity change. The field observations showed significant heterogeneity of fluid flow and for the first time clearly demonstrated that fluid flow evolved with time and injection rate. It was found the wells were connected through numerous, separate flow pathways. CO2 flowed through an increasing fraction of the reservoir and sweep efficiency improved with time. The field study also first documented in situ component exchange between brine and gas phases during CO2 injection. It was found that CH4 degassed from brine and is enriched along the gas-water contact. Multiple injectate flow fronts with high CH4 concentration arrived at different times and led to gas composition fluctuations in the observation wells. The findings provide valuable insights into heterogeneous multiphase flow in rock formations and show that conventional geological models and static fluid flow simulations are unable to fully describe the heterogeneous and dynamic flow during fluid injection.

Lu, Jiemin; Cook, Paul J.; Hosseini, Seyyed A.; Yang, Changbing; Romanak, Katherine D.; Zhang, Tongwei; Freifeld, Barry M.; Smyth, Rebecca C.; Zeng, Hongliu; Hovorka, Susan D.

2012-03-01

274

The morphodynamic impact of vegetation and large wood on fluvial systems  

NASA Astrophysics Data System (ADS)

We present preliminary results from a set of recent experiments conducted in the Total Environment Simulator flume at the University of Hull in the framework of the Hydralab IV EU project. The aim of these experiments is to identify and assess the effects of riparian vegetation and large wood on the morphodynamics of braided river channels. The type and size of riparian vegetation is known to play a crucial role in shaping rivers, acting as a proper riparian engineer. Riparian vegetation influences bank stability, increases mean channel depth and can affect planform pattern by reducing the number of active branches. However, the geomorphic effect of plants can continue well after their erosion from banks. As dead or living pieces of large wood are transported through the fluvial network, they can exert a tremendous influence on river erosion and sedimentation processes, channel morphology, channel hydraulics, and ecological diversity of river channels. Our experiments consisted of different scenarios of presence / absence of riparian vegetation (simulated using alfalfa sprouts) and large wood density (simulated using wooden dowels). The experiments were designed to assess both the individual effects of woody debris and bank vegetation, as well as their combined effects. Each experiment has been characterised in terms of planform configuration (the number of active branches per cross-section) and bed topography (surveyed by a terrestrial laser scanner). Detailed DEM differencing was used to investigate sediment transport patterns and dynamics for the different vegetation-wood scenarios. The results of this work will help improve the ability to predict the response of river systems to different disturbances and management strategies.

Mao, L.; Bertoldi, W.; Comiti, F.; Gurnell, A. M.; McLelland, S. J.; Osei, N.; Ravazzolo, D.; Tal, M.; Welber, M.; Zanella, S.

2012-04-01

275

Hydraulic Conductivity Structure and Multivariate Facies Associations in a Conglomeratic Fluvial Aquifer, Boise Hydrogeophysical Research Site  

NASA Astrophysics Data System (ADS)

Knowledge of the distribution of hydraulic conductivity (K) at high-resolution in heterogeneous aquifers is important for modeling fundamental hydrologic processes, investigation and remediation of groundwater contamination, and understanding petrophysical relations or multivariate associations between hydraulic, lithologic, and geophysical parameters. We examine K structure in the conglomeratic fluvial aquifer at the Boise Hydrogeophysical Research Site using high-resolution K data from multi-level slug tests alone and in combination with porosity, capacitive conductivity (CC), and grain-size distribution (GSD) data. Results indicate K structural organization is similar to that described by Jussel et al. (1994): facies bodies of various types at a range of scales distributed within more massive 'host' layers or volumes. K-facies types are related to previously-established stratigraphy by occurrence within (vs across) stratigraphic units and by multivariate parameter trends and associations. However, K-facies have both positive and negative associations with porosity that occur systematically in the stratigraphy. Petrophysical (correlation) relations are not evident between K-porosity-CC although K-facies are distinguished by statistically significant multivariate parameter associations. Also, multivariate analysis including GSD information indicates K variation occurs by different combinations of porosity, cobble fraction, and size and sorting characteristics which also change in polarity (rather than having monotonic relations) as K or porosity increase or decrease. Taken together, results explain why prediction of K with a single petrophysical relation or facies association scheme should not be assumed automatically in coarse conglomeratic deposits. Also, with importance for transport behavior, significantly different K and porosity distributions may be common in these deposits.

Barrash, W.; Cardiff, M. A.

2013-12-01

276

Relationship between fluvial morphodynamics and basin-filling sedimentation patterns: Lessons learned from physical experiments  

NASA Astrophysics Data System (ADS)

The evenness or unsteadiness with which sedimentary systems move across and fill basins imparts fundamental patterns into the stratigraphic record. Recent studies show that paleoenvironmental (allogenic) signals preserved in the stratigraphic record may be contaminated or overprinted by internally generated (autogenic) sedimentation patterns; however, it is currently unclear over what temporal and spatial scales autogenic patterns are most prevalent. Basin-filling patterns are determined by fluvial morphodynamics and subsidence patterns in channelized systems; consequently, constraining long-timescale autogenic processes provides a way of evaluating autogenic stratigraphic patterns and scales in sedimentary deposits. Utilizing recently developed statistical methods, we quantify basin filling trends in three laboratory experiments and compare stratigraphic organization to avulsion behavior. Specifically we use the compensation index, a measure of the rate of decay of spatial variability in sedimentation between picked depositional horizons with increasing vertical stratigraphic averaging distance, to estimate stratigraphic organization. In the three experiments topography of channelized deltas formed by weakly cohesive sediment were monitored along flow-perpendicular transects at a high temporal resolution relative to channel kinematics. Over the course of the experiments a uniform relative subsidence pattern, designed to isolate autogenic processes, resulted in the construction of stratigraphic packages in excess of 25 times the depth of the experimental channels. We explore how the compensation index, and thus the degree of stratigraphic organization varies as functions of 1) time-scale of measurement, 2) relative proximal to distal location in a basin, 3) the ratio of sediment discharge to water discharge and 4) the size of a sediment transport system relative to the basin it is filling.

Straub, K. M.; Wang, Y.

2011-12-01

277

Fluvial response to Holocene volcanic damming and breaching in the Gediz and Geren rivers, Western Turkey  

NASA Astrophysics Data System (ADS)

This study discusses the complex late Holocene evolution of the Gediz River North of Kula, Western Turkey, when a basaltic lava flow dammed and filled this river valley. Age control was obtained using established and novel feldspar luminescence techniques on sands below and on top of the flow. This constrained the age of the lava flow to 3.0 - 2.1 ka. In addition, 40Ar/39Ar dating was attempted but due a combination of the young age and low potassium content of the basalt this technique was unsuitable. Two damming locations caused by the lava flow have been investigated. The upstream dam caused lake formation and silting of the upstream Gediz. The downstream dam blocked both the Gediz and its tributary, the Geren. The associated lake was not silted up because the upstream dam already trapped all the Gediz sediments. Backfillings of the downstream lake are found 1.5 km upstream into the Geren valley. The downstream dam breached first, after which the upstream dam breached creating an outburst flood that imbricated boulders of approx. 10 m3 size and created an epigenetic gorge. The Gediz lowered its floodplain level with at least 15 m in a short time, triggering landslides, some of which are active until present. The lower reach of the Geren has experienced fast base level lowering and changed regime from meandering to a straight channel. Complex response to base level change is still on-going in both Geren and Gediz catchments. These findings are summarized in a diagram conceptualizing lava damming and breaching events. It is concluded that one lava flow filling a valley floor can block a river several times, leading to different, but interrelated fluvial responses of the same river system to the same lava flow.

van Gorp, Wouter; Veldkamp, Antonie; Temme, Arnaud; Maddy, Darrel; Demir, Tuncer; van der Schriek, Tim; Reimann, Tony; Wallinga, Jakob; Wijbrans, Jan; Schoorl, Jeroen

2013-04-01

278

Effects of river hydrology and fluvial processes on riparian vegetation establishment, growth, and survival  

NASA Astrophysics Data System (ADS)

Stream hydrology, sediment, and geology interact to determine the spatial and temporal availability of river bottomland substrates on which plants establish and grow. Collectively, these surfaces comprise a mosaic of landscape patches with associated plant communities that fall along key gradients of physical disturbance and water availability. Aspects of flow such as magnitude, frequency, timing, and rate of change of floods and magnitude and duration of low flows, interact with sediment flux and plant traits to determine plant distribution and fitness in different parts of the bottomland. Flow and sediment dynamics can influence different aspects of the plant life cycle such as germination, establishment, growth, and survival. Feedbacks between plants and fluvial processes, such as increased surface roughness and associated reductions in flow velocity and potential for aggradation, can determine differential survival of plant species depending on their tolerance of high velocity flow and associated shear stress, dislodgement, or burial by sediment. We present an overview of some key relationships between flow, sediment, plant traits, and riparian vegetation responses, and provide specific examples from our research on rivers in the semi-arid western U.S., including unaltered systems, dam-altered systems, and in the context of development of environmental flows to restore native riparian vegetation communities. Further, we describe the riparian response guilds framework and demonstrate how it can facilitate both an understanding of vegetation response to changing flow, sediment, and disturbance regimes and the development of priorities for flow management. Through understanding how guilds of species respond to variations in flow and sediment regimes, we are be better able to anticipate and predict biotic change in response to human-caused and climate-driven flow alteration.

Shafroth, P. B.; Merritt, D. M.; Wilcox, A. C.

2012-12-01

279

Pleistocene fluvial sediments, palaeontology and archaeology of the upper River Thames at Latton, Wiltshire, England  

NASA Astrophysics Data System (ADS)

Pleistocene fluvial sediments of the Northmoor Member of the Upper Thames Formation exposed at Latton, Wiltshire, record episodic deposition close to the Churn-Thames confluence possibly spanning the interval from Marine Isotope Stages (MIS) 7 to 2. The sequence is dominated by gravel facies, indicating deposition by a high-energy, gravel-bed river. A number of fine-grained organic sediment bodies within the sequence have yielded palaeoenvironmental and biostratigraphical data from Mollusca, Coleoptera, vertebrates, pollen and plant macrofossils. The basal deposit (Facies Association A) contains faunal material indicating temperate conditions. Most of the palaeontological evidence including a distinctive small form of mammoth (Mammuthus cf. trogontherii), together with the U-series age estimate of >147.4 +/- 20 kyr suggest correlation with MIS 7. The overlying deposits (Facies Associations B and C) represent deposition under a range of climatic conditions. Two fine-grained organic deposits occurred within Association B; one (Association Ba) in the northern part of the pit as a channel fill and the other (Association Bb) in its southern part as a scour-fill deposit. The coleopteran assemblages from Ba, indicate that it accumulated under temperate oceanic conditions, while Bb, which also yielded a radiocarbon age estimate of 39 560 +/- 780 14C yr BP, was formed under much colder and more continental climatic conditions. The sequence is considered to represent deposition within an alluvial fan formed at the Churn-Thames confluence; a depositional scenario which may account for the juxtaposition of sediments and fossils of widely differing age within the same altitudinal range.

Lewis, S. G.; Maddy, D.; Buckingham, C.; Coope, G. R.; Field, M. H.; Keen, D. H.; Pike, A. W. G.; Roe, D. A.; Scaife, R. G.; Scott, K.

2006-02-01

280

Evaluation of statistical models for predicting Escherichia coli particle attachment in fluvial systems.  

PubMed

Modeling surface water Escherichia coli fate and transport requires partitioning E. coli into particle-attached and unattached fractions. Attachment is often assumed to be a constant fraction or is estimated using simple linear models. The objectives of this study were to: (i) develop statistical models for predicting E. coli attachment and virulence marker presence in fluvial systems, and (ii) relate E. coli attachment to a variety of environmental parameters. Stream water samples (n = 60) were collected at four locations in a rural, mixed-use watershed between June and October 2012, with four storm events (>20 mm rainfall) being captured. The percentage of E. coli attached to particles (>5 ?m) and the occurrences of virulence markers were modeled using water quality, particle concentration, particle size distribution, hydrology and land use factors as explanatory variables. Three types of statistical models appropriate for highly collinear, multidimensional data were compared: least angle shrinkage and selection operator (LASSO), classification and regression trees using the general, unbiased, interaction detection and estimation (GUIDE) algorithm, and multivariate adaptive regression splines (MARS). All models showed that E. coli particle attachment and the presence of E. coli virulence markers in the attached and unattached states were influenced by a combination of water quality, hydrology, land-use and particle properties. Model performance statistics indicate that MARS models outperform LASSO and GUIDE models for predicting E. coli particle attachment and virulence marker occurrence. Validating the MARS modeling approach in multiple watersheds may allow for the development of a parameterizing model to be included in watershed simulation models. PMID:24075474

Piorkowski, Gregory; Jamieson, Rob; Bezanson, Greg; Hansen, Lisbeth Truelstrup; Yost, Chris

2013-11-01

281

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

SciTech Connect

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.

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

282

Ecotoxicity of fluvial sediments downstream of the Ajka red mud spill, Hungary.  

PubMed

An integrated assessment of biological activity and ecotoxicity of fluvial sediments in the Marcal river catchment (3078 km(2)), western Hungary, is presented following the accidental spill of bauxite processing residue (red mud) in Ajka. Red mud contaminated sediments are characterised by elevated pH, elevated trace element concentrations (e.g. As, Co, Cr, V), high exchangeable Na, and induce an adverse effect on test species across a range of trophic levels. While background contamination of the river system is highlighted by adverse effects on some test species at sites unaffected by red mud, the most pronounced toxic effects apparent in Vibrio fischeri bioluminescence inhibition, Lemna minor bioassay and Sinapis alba root and shoot growth occur at red mud depositional hotspots in the lower Torna Creek and upper Marcal. Heterocypris incongruens bioassays show no clear patterns, although the most red mud-rich sites do exert an adverse effect. Red mud does however appear to induce an increase in the density of aerobic and facultative anaerobic bacterial communities when compared with unaffected sediments and reference sites. Given the volume of material released in the spill, it is encouraging that the signal of the red mud on aquatic biota is visible at a relatively small number of sites. Gypsum-affected samples appear to induce an adverse effect in some bioassays (Sinapis alba and Heterocypris incongruens), which may be a feature of fine grain size, limited nutrient supply and greater availability of trace contaminants in the channel reaches that are subject to intense gypsum dosing. Implications for monitoring and management of the spill are discussed. PMID:22772744

Klebercz, Orsolya; Mayes, William M; nton, Aron Dniel; Feigl, Viktria; Jarvis, Adam P; Gruiz, Katalin

2012-08-01

283

Reservoir and aquifer characterization of fluvial architectural elements: Stubensandstein, Upper Triassic, southwest Germany  

NASA Astrophysics Data System (ADS)

This paper aims at a quantitative sedimentological and petrophysical characterization of a terminal alluvial plain system exemplified by the Stubensandstein, South German Keuper Basin. The study follows the outcrop-analogue approach, where information derived from outcrops is collected in order to enhance interpretation of comparable subsurface successions. Quantitative data on sandbody geometries, porosities and permeabilities are presented in order to constrain modelling of subsurface sandbodies and permeability barriers. For sedimentological characterization the method of architectural element analysis (Miall, A.D., 1996. The Geology of Fluvial Deposits. Springer, Berlin) was used, and modified to include poroperm facies. A special photo-technique with a precise theodolite survey was developed to create optically corrected photomosaics for outcrop wall maps from up to 20,000 m 2 large outcrops. Nine architectural elements have been classified and quantified. Bedload, mixed-load and suspended-load channel fills are separated. The petrophysical characterization of the architectural elements integrated porosity and permeability measurements of core-plugs with gamma-ray measurements along representative sections. It could be demonstrated, that certain architectural elements show a characteristic poroperm facies. Four scales of sedimentary cycles have been recognized in the Stubensandstein. Cyclic sedimentation causes changing lithofacies patterns within the architectural elements, depending on their position in the sedimentary cycle. Stratigraphic position exerts only some, paleogeographic position exerts significant influence on porosity and permeability of the sandbodies. The highest poroperm values were found in proximal areas of the alluvial plain and in middle parts within sedimentary macrocycles. The strong internal heterogeneity on the alluvial plain system is important for its reservoir and aquifer characteristics. Compartments of bedload channel sandstones in medial positions of a stratigraphic cycle represent very good reservoirs or aquifers. The seals or aquicludes are formed by extensive floodplain claystones, lacustrine sediments, paleosols, and suspended-load deposits. Strongly cemented zones of sandstones represent aquitards.

Hornung, Jens; Aigner, Thomas

1999-12-01

284

Improved Oil Recovery In Fluvial Dominated Deltaic Reservoirs of Kansas - Near Term  

SciTech Connect

Common oil field problems exist in fluvial dominated deltaic reservoirs in Kansas. The problems are poor waterflood sweep efficiency 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 injection wells due to solids in the injection water. In many instances the lack of reservoir management results from (1) poor data collection and organization, (2) little or no integrated analysis of existing data by geological and engineering personnel, (3) the presence of multiple operators within the field, and (4) not identifying optimum recovery techniques. Two demonstration sites operated by different independent oil operators are involved in this project. The Stewart Field is located in Finney County, Kansas and is operated by PetroSantander, Inc. This field was in the latter stage of primary production at the beginning of this project and is currently being waterflooded as a result of this 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 objective is to increase recovery efficiency and economics in these types 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.

Green, Don W.; McCune, D.; Michnick, M.; Reynolds, R.; Walton, A.; Watney, L.; Willhite, G. Paul

1999-01-14

285

Sediment sources, spatiotemporal variability and rates of fluvial bedload transport in glacier-connected steep mountain valleys in western Norway (Erdalen and Bdalen drainage basins)  

NASA Astrophysics Data System (ADS)

Contemporary fluvial bedload transport rates are still very difficult to measure and, as a result of this, in many sites only quantitative data on suspended and solute transport are included in sediment budget studies carried out for defined drainage basin systems. The presented analysis of fluvial bedload dynamics in different defined subsystems of the glacier-connected Erdalen (79.5 km2) and Bdalen (60.1 km2) drainage basins in the steep fjord landscape of western Norway provides insights into (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 valleys. 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 drainage basins are not of importance as all bedload material delivered directly from these outlet glaciers is trapped within proglacial lakes. 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 the main stream channels than wider valleys. Snow avalanches are the most important sediment source in Erdalen, whereas fluvial transfers through small tributaries followed by snow avalanches are most important in Bdalen. Longer term, instream channel storage is not of great importance in the steep Bdalen drainage basin 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 less steep main channel reaches. The 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 Bdalen drainage basin, which are comparably low values for steep and partly glacierized drainage basin systems. Because of supply-limited conditions, the intensity of fluvial bedload transport is generally much more related to the availability of sediments than to channel discharge. Fluvial bedload transport accounts for about one-third of the total fluvial transport and accordingly plays an important role within the sedimentary budgets of both drainage basin systems.

Beylich, Achim A.; Laute, Katja

2015-01-01

286

Seismic stratigraphy of the Messinian Nile Delta coastal plain: Recognition of the fluvial Regressive Systems Tract and its potential for hydrocarbon exploration  

NASA Astrophysics Data System (ADS)

The Upper Miocene strata of the Nile Delta (Egypt) record the dramatic events of the Messinian opening and closing of the Mediterranean Sea. Furthermore, the complexity of the associated stratigraphic relations within the Lower Messinian Qawasim and the Upper Messinian Abu Madi formations contribute to present challenges in their effective gas exploration and production. Through recognition and delineation of the Regressive Systems Tract on the Messinian Nile coastal plain, a new understanding of fluvial responses to changes in sea level as observed in the sedimentary record and to its optimal hydrocarbon reservoir exploration may be obtained. Seismic stratigraphic analysis of 1800 km of 2D seismic with eighteen boreholes of these two formations reveals the dynamic interplay between fluvial downcutting and fill as a response to global and Mediterranean sea level oscillations. The observation of fluvial channel terraces on the delta plain during downstepping relative sea level falls reveal correlatable RST (Regressive Systems Tract) terraces incised by LST channels and then subsequent flooding by TST delta incised back stepping channel fills culminating in HST (High Systems Tract) deposition. While the Qawasim fluvial downcutting and fill are in response to global sea level changes, the Abu Madi responses are antithetic to global sea level changes. Specifically, the RST channels of the Qawasim Formation are represented by fluvial terraces of lateral accretion units in response to downward stepping base levels owing to a slowly falling global sea level base and shale channel fill during a global sea level rise. The RST channels of the Abu Madi Formation are represented by incised valley fluvial channels which eroded most of Qawasim Formation deposits especially in the northward of Nile Delta in response to rapidly falling local sea level as the Mediterranean Sea was cut off from the global ocean then are capped by a rapid transgression when the Mediterranean suddenly reopened. The RST and LST in both the Qawasim and Abu Madi fluvial channels exhibit potentially good reservoir continuity, sand quality, and charging potential. Productive boreholes confirm the hydrocarbon potential of the RST and LST in the Qawasim and the LST in the Abu Madi. Proper understanding and interpretation of the coastal fluvial RST stages on sand deposition as a response to sea level changes are a key issue in assessing Messinian reservoir quality of the Nile Delta and for coastal fluvial deposits elsewhere in the world.

Pigott, John D.; Abdel-Fattah, Mohamed I.

2014-07-01

287

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

288

Late cenozoic fluvial stratigraphy of the New Jersey piedmont: A record of glacioeustasy, planation, and incision on a low-relief passive margin  

USGS Publications Warehouse

Late Cenozoic fluvial deposits and erosional landforms in the New Jersey Piedmont record two episodes of valley incision, one in the Late Miocene and one in the Early Pleistocene, separated by periods of planation and fluvial deposition. The upland erosion surface and a fluvial gravel are the remnants of a low-relief Late Miocene landscape. Late Miocene incision was followed by deposition of a fluvial plain and cutting of straths in the Pliocene. Early Pleistocene incision produced the present valleys, which contain Middle to Late Pleistocene fluvial deposits. The two incisions correspond to permanent glacioeustatic lowering during expansion of the Antarctic ice sheet in the Middle to Late Miocene and development of Northern Hemisphere ice sheets in the Late Pliocene. Bordering Coastal Plain marine deposits indicate that the upland erosion surface was formed during a rising sea-level trend between the Late Oligocene and Middle Miocene. The Pliocene plain and straths formed during a period of rising sea level in the Early Pliocene. The stratigraphic record indicates that the oldest preserved landforms are no older than Late Miocene, that landscape planation in coastal regions of low-relief passive margins can be achieved in <20 m.yr., and that these surfaces can be incised and dissected in <5 m.yr.

Stanford, S.D.; Ashley, G.M.; Brenner, G.J.

2001-01-01

289

An Intense Terminal Epoch of Widespread Fluvial Activity on Early Mars: 2. Increased Runoff and Paleolake Development  

NASA Technical Reports Server (NTRS)

To explain the much higher denudation rates and valley network development on early Mars (more than approximately 3.6 Gyr ago), most investigators have invoked either steady state warm/wet (Earthlike) or cold/dry (modern Mars) end-member paleoclimates. Here we discuss evidence that highland gradation was prolonged, but generally slow and possibly ephemeral during the Noachian Period, and that the immature valley networks entrenched during a brief terminal epoch of more erosive fluvial activity in the late Noachian to early Hesperian. Observational support for this interpretation includes (1) late-stage breaching of some enclosed basins that had previously been extensively modified, but only by internal erosion and deposition; (2) deposition of pristine deltas and fans during a late stage of contributing valley entrenchment; (3) a brief, erosive response to base level decline (which was imparted as fretted terrain developed by a suite of processes unrelated to surface runoff) in fluvial valleys that crosscut the highland-lowland boundary scarp; and (4) width/contributing area relationships of interior channels within valley networks, which record significant late-stage runoff production with no evidence of recovery to lower-flow conditions. This erosion appears to have ended abruptly, as depositional landforms generally were not entrenched with declining base level in crater lakes. A possible planetwide synchronicity and common cause to the late-stage fluvial activity are possible but remain uncertain. This increased activity of valley networks is offered as a possible explanation for diverse features of highland drainage basins, which were previously cited to support competing warm, wet and cold, dry paleoclimate scenarios.

Rossman III, Irwin P.; Howard, Alan D.; Craddock, Robert A.; Moore, Jeffrey M.

2005-01-01

290

Fluvial baselevel changes in the lower part of the White River Group, Eocene-Oligocene, Badlands of South Dakota  

SciTech Connect

The Chamberlain Pass Formation (CPF) is a Middle( ) to Late Eocene fluvial unit that represents the lower part of the White River Group in western South Dakota. The CPF consists of multistory channel sandstone and overbank mudstone, both overprinted by a distinctive paleosol unit, the Interior Paleosol Series. The CPF thickens from west to east, to a maximum channel-belt thickness [ge] 11 m. Paleoflow data indicates that deposition of the CPF was restricted to an asymmetric basin controlled by faults trending Se, away from the Black Hills uplift. Sandstones in the CPF contain a suite of resistant minerals derived from a recycled sedimentary rock source area. In contrast, the overlying Chadron Formation contains a suite of minerals and rock fragments consistent with a source area from the igneous and metamorphic core rocks of the Black Hills uplift. The deposition of the CPF brackets four significant changes in relative baselevel that occurred in this region during the Paleogene: (1) Late Cretaceous to Middle( ) Eocene baselevel fall, weathering and erosion of the Cretaceous Pierre Shale to form the Yellow Mounds Paleosol, and fluvial incision; (2) Middle( ) to Late Eocene baselevel rise and deposition of the CPF; (3) Late Eocene baselevel fall, weathering and erosion of the CPF to form the Interior Paleosol, and fluvial incision; and (4) late Eocene to Oligocene baselevel rise and deposition of the Chadron formation. The first event was eustatic, the second was controlled primarily by subsidence in a fault-controlled basin, the third records tectonic uplift and unroofing of the Black Hills, and the fourth was controlled by a combination of eustatic, tectonic, and paleoclimatic factors.

Evans, J.E. (Bowling Green State Univ., OH (United States). Dept. of Geology); Terry, D.O. Jr. (Univ. of Nebraska, Lincoln, NE (United States). Dept. of Geology)

1992-01-01

291

Predicting interwell heterogeneity in fluvial-deltaic reservoirs: Outcrop observations and applications of progressive facies variation through a depositional cycle  

SciTech Connect

Nearly 11 billion barrels of mobile oil remain in known domestic fluvial-deltaic reservoirs despite their mature status. A large percentage of this strategic resource is in danger of permanent loss through premature abandonment. Detailed reservoir characterization studies that integrate advanced technologies in geology, geophysics, and engineering are needed to identify remaining resources that can be targeted by near-term recovery methods, resulting in increased production and the postponement of abandonment. The first and most critical step of advanced characterization studies is the identification of reservoir architecture. However, existing subsurface information, primarily well logs, provides insufficient lateral resolution to identify low-permeability boundaries that exist between wells and compartmentalize the reservoir. Methods to predict lateral variability in fluvial-deltaic reservoirs have been developed on the basis of outcrop studies and incorporate identification of depositional setting and position within a depositional cycle. The position of a reservoir within the framework of a depositional cycle is critical. Outcrop studies of the Cretaceous Ferron Sandstone of Utah have demonstrated that the architecture and internal heterogeneity of sandstones deposited within a given depositional setting (for example, delta front) vary greatly depending upon whether they were deposited in the early, progradational part of a cycle or the late, retrogradational part of a cycle. The application of techniques similar to those used by this study in other fluvial-deltaic reservoirs will help to estimate the amount and style of remaining potential in mature reservoirs through a quicklook evaluation, allowing operators to focus characterization efforts on reservoirs that have the greatest potential to yield additional resources.

Knox, P.R.; Barton, M.D. [Univ. of Texas, Austin, TX (United States)

1997-08-01

292

Toward the Validation of Depth-Averaged Three Dimensional, Rans Steady-State Simulations of Fluvial Flows at Natural Scale  

NASA Astrophysics Data System (ADS)

Simulations of fluvial flows are strongly influenced by geometric complexity and overall uncertainty on measured flow variables, including those assumed to be well known boundary conditions. Often, 2D steady-state models are used for computational simulations of flows at the scale of natural rivers. Such models have been successfully incorporated in iRIC (formerly MD_SWMS), one of the widely used quasi-3D CFD solvers to perform studies of environmental flows. iRIC aids in estimating such quantities as surface roughness and shear stress, which, in turn, can be used to estimate sediment transport. However, the computational results are inherently limited in accuracy because of restricting the computations to 2D, or quasi-3D, space, which can affect the values of these predictions. In the present work we perform computer-based simulations of fluvial flows using OpenFOAM, a free, open source fully 3D CFD software package, and compare our results to predictions obtained from iRIC. First, we study the suitability of OpenFOAM as the main CFD solver to analyze fluvial flows and validate our results for two well documented rectangular channel configurations: the first case consists of a large aspect-ratio channel (ratio of depth over width 0.017, ratio of depth over length 0.0019) with a rectangular obstacle mounted at the bottom wall; the second case involves a large aspect-ratio channel (ratio of depth over width 0.1, ratio of depth over length 0.0025) with cubic obstacles mounted at the lower wall (one obstacle) and upper wall (two obstacles). Secondly, we apply our model to simulation or river at natural scale and compare our results to the output obtained from iRIC to quantify the differences in velocity profiles and other flow parameters when comparable solution techniques are used. Steady-state, RANS k-epsilon models are employed for all simulations.

Mateo Villanueva, P. A.; Hradisky, M.

2010-12-01

293

Flood of February 1980 along the Agua Fria River, Maricopa County, Arizona  

USGS Publications Warehouse

The flood of February 20, 1980, along the Agua Fria River below Waddell Dam, Maricopa County, Ariz., was caused by heavy rains during February 13-20. The runoff filled Lake Pleasant and resulted in the largest release--66,600 cubic feet per second--from the reservoir since it was built in 1927; the maximum inflow to the reservoir was about 73,300 cubic feet per second. The area inundated by the releases includes about 28 miles along the channel from the mouth of the Agua Fria River to the Beardsley Canal flume crossing 5 miles downstream from Waddell Dam. The flood of 1980 into Lake Pleasant has a recurrence interval of about 47 years, whereas the flood of record (1919) has a recurrence interval of about 100 years. (USGS)

Thomsen, B.W.

1980-01-01

294

SEISMIC STUDY OF THE AGUA DE PAU GEOTHERMAL PROSPECT, SAO MIGUEL, AZORES.  

USGS Publications Warehouse

A 16 station array was operated over the 200 km**2 central portion of Sao Miguel utilizing 8 permanent Instituto Nacional de Meterologia e Geofisica stations and 8 USGS portable stations. Forty four local events with well constrained solutions and 15 regional events were located. In addition, hundreds of unlocatable seismic events were recorded. The most interesting seismic activity occurred in a swarm on September 6 and 7, 1983 when over 200 events were recorded in a 16 hour period. The seismic activity around Agua de Pau was centered on the east and northeast slopes of the volcano. The data suggest a boiling hydrothermal system beneath the Agua de Pau volcano, consistent with a variety of other data.

Dawson, Phillip B.; Rodrigues da Silva, Antonio; Iyer, H.M.; Evans, John R.

1985-01-01

295

Stratigraphic correlation of oligocene marginal marine and fluvial deposits across the middle and lower coastal plain, South Carolina  

NASA Astrophysics Data System (ADS)

The age and stratigraphic relationship of the Upland Unit, which crops out at the Savannah River Site near Barnwell, South Carolina has been the focus of many recent investigations. The geological interpretation of the Upland Unit is particularly significant since it serves as the upper confining unit used in the storage of lowlevel radioactive wastes at the Savannah River Site. The age and regional extent of the unit is also important in providing an accurate geological map of the upper coastal plain. The age of the Upland Unit has been in dispute because it lacks datable material. Extensive coring and seismic studies have been conducted to investigate the occurrence and regional distribution of this stratigraphic unit. Lithologically, the Upland Unit consists of poorly sorted, clayey to silty, medium- to coarse-grained sands and gravels of fluvial origin. Similar quartz gravel deposits have been reported from the Chandler Bridge Formation near Charleston, South Carolina. These 'Upland-like' gravels are the oldest gravels of Tertiary age reported in the lower coastal plain. The Chandler Bridge Formation is interpreted as a downdip marginal marine facies of an extensive fluvial drainage system which once extended from the upper to the lower coastal plain of South Carolina. Where present, the Chandler Bridge Formation is overlain by nodular phosphate deposits of the Edisto Formation (late Oligocene to early Miocene), and underlain by the Ashley Formation of late Oligocene age. Pollen and dinoflagellate analyses conducted on sediment samples also confirm a late Chattian age for the Chandler Bridge Formation. Consequently, if quartz clasts in the Chandler Bridge Formation represent fluvial transport of Upland Unit gravels from the upper coastal plain which seems likely, then the age of the Upland Unit can be no younger than late Oligocene. Lithologic and stratigraphic analyses suggest that the Upland Unit and the Chandler Bridge Formation are correlative and represent a sequence of fluvial and marginal marine deposits of late Oligocene age. The depositional history of these formational units provides additional information concerning the geological evolution of the middle and lower coastal plain of South Carolina.

Katuna, Michael P.; Geisler, Jonathan H.; Colquhoun, Donald J.

1997-02-01

296

Hydrologic characteristics of the Agua Fria National Monument, central Arizona, determined from the reconnaissance study  

USGS Publications Warehouse

Hydrologic conditions in the newly created Agua Fria National Monument were characterized on the basis of existing hydrologic and geologic information, and streamflow data collected in May 2002. The study results are intended to support the Bureau of Land Management's future water-resource management responsibilities, including quantification of a Federal reserved water right within the monument. This report presents the study results, identifies data deficiencies, and describes specific approaches for consideration in future studies. Within the Agua Fria National Monument, the Agua Fria River flows generally from north to south, traversing almost the entire 23-mile length of the monument. Streamflow has been measured continuously at a site near the northern boundary of the monument since 1940. Streamflow statistics for this site, and streamflow measurements from other sites along the Agua Fria River, indicate that the river is perennial in the northern part of the monument but generally is intermittent in downstream reaches. The principal controls on streamflow along the river within the monument appear to be geology, the occurrence and distribution of alluvium, inflow at the northern boundary and from tributary canyons, precipitation, and evapotranspiration. At present, (2004) there is no consistent surface-water quality monitoring program being implemented for the monument. Ground-water recharge within the monument likely results from surface-water losses and direct infiltration of precipitation. Wells are most numerous in the Cordes Junction and Black Canyon City areas. Only eight wells are within the monument. Ground-water quality data for wells in the monument area consist of specific-conductance values and fluoride concentrations. During the study, ground-water quality data were available for only one well within the monument. No ground-water monitoring program is currently in place for the monument or surrounding areas.

Fleming, John B.

2005-01-01

297

Sedimentology of the lower Karoo Supergroup fluvial strata in the Tuli Basin, South Africa  

NASA Astrophysics Data System (ADS)

The Karoo Supergroup in the Tuli Basin (South Africa) consists of a sedimentary sequence (450-500 m) composed of four stratigraphic units, namely the informal Basal, Middle and Upper Units, and the formal Clarens Formation. The units were deposited in continental settings from approximately Late Carboniferous to Middle Jurassic. This paper focuses on the 60-m-thick Basal Unit, which was examined in terms of sedimentary facies and palaeo-environments based on evidence provided by primary sedimentary structures, palaeo-flow measurements, palaeontological findings, borehole data (59 core descriptions) and stratigraphic relations. Three main facies associations have been identified: (i) gravelstone (breccias and conglomerate-breccias), (ii) sandstone and (iii) fine-grained sedimentary rocks. The coarser facies are interpreted as colluvial fan deposits, possibly associated with glaciogenic diamictites. The sandstone facies association is mainly attributed to channel fills of low sinuosity, braided fluvial systems. The coal-bearing finer-grained facies are interpreted as overbank and thaw-lake deposits, and represent the lower energy correlatives of the sandy channel fills. Sediment aggradation in this fluvio-lacustrine system took place under cold climatic conditions, with floating lake ice likely associated with lacustrine environments. Palaeo-current indicators suggest that the highly weathered, quartz-vein-rich metamorphic rock source of the Basal Unit was situated east-northeast of the study area. The accumulation of the Basal Unit took place within the back-bulge depozone of the Karoo foreland system. In addition to flexural subsidence, the amount of accommodation in this tectonic setting was also possibly modified by extensional tectonism in the later stages of the basin development. Based on sedimentological and biostratigraphic evidence, the coal-bearing fine-grained facies association displays strong similarities with the Vryheid Formation of the main Karoo Basin to the south. The lowermost non-fossiliferous breccias have been correlated before with the Dwyka Group in the main Karoo, and hence the Basal Unit may be regarded as the distal equivalent of the Dwyka and Ecca groups to the south.

Bordy, Emese M.; Catuneanu, Octavian

2002-11-01

298

Paleochannel and paleohydrology of a Middle Siwalik (Pliocene) fluvial system, northern India  

NASA Astrophysics Data System (ADS)

Late Cenozoic fresh water molasses sediments (+6000 m thick) deposited all along the length of the Himalayan fore deep, form the Siwalik Supergroup. This paper reports the results of the paleodrainage and paleohydrology of the Middle Siwalik sub-group of rocks, deposited in non-marine basins adjacent to a rising mountain chain during Pliocene. Well-exposed sections of these rocks have provided adequate paleodrainage data for the reconstruction of paleochannel morphology and paleohydrological attributes of the Pliocene fluvial system. Cross-bedding data has been used as inputs to estimate bank full channel depth and channel sinuosity of Pliocene rivers. Various empirical relationships of modern rivers were used to estimate other paleohydrological attributes such as channel width, sediment load parameter, annual discharge, and channel slope and flow velocity. Computed channel depth, channel slope and flow velocity are supported independently by recorded data of scour depth, cross-bedding variability and Chezy's equation. The estimates indicate that the Middle Siwalik sequence corresponds to a system of rivers, whose individual channels were about 400 m wide and 5.2-7.3 m deep; the river on an average had a low sinuous channel and flowed over a depositional surface sloping at the rate of 53 cm/km. The 700-km-long Middle Siwalik (Pliocene) river drained an area of 42925 km2 to the north-northeast, with a flow velocity of 164-284 cm/s, as it flowed generally south-southwest of the Himalayan Orogen. Bed-load was about 15% of the total load of this river, whose annual discharge was about 346-1170 m3/s normally and rose to approximately 1854 m3/s during periodic floods. The Froude number of 0.22 suggests that the water flows in the Pliocene river channels were tranquil, which in turn account for the profuse development of cross-bedded units in the sandstone. The estimated paleochannel parameters, bedding characteristics and the abundance of coarse clastics in the lithic fill are rather similar to the modern braided rivers of Canada and India such as South Sackatchewan and Gomti, respectively.

Khan, Z. A.; Tewari, R. C.

2011-06-01

299

Human and natural impacts on fluvial and karst depressions of the Maya Lowlands  

NASA Astrophysics Data System (ADS)

This paper begins to differentiate the major drivers and chronology of erosion and aggradation in the fluvial and fluviokarst landscapes of the southern and central Maya Lowlands. We synthesize past research on erosion and aggradation and add new data from water, soils, radiocarbon dating, and archaeology to study the quantity, timing, and causes of aggradation in regional landscape depressions. Geomorphic findings come from many excavations across a landscape gradient from upland valleys, karst sinks, and fans into the coastal plain floodplains and depressions. Findings from water chemistry show that sources in the uplands have low quantities of dissolved ions but water in the coastal plains has high amounts of dissolved ions, often nearly saturated in calcium and sulfate. We found significant geomorphic complexity in the general trends in upland karst sinks. In a few instances, sediments preserve Late Pleistocene paleosols, buried 2-3 m, though many more have distinct middle to late Holocene paleosols, buried 1-2 m, after c. 2300 BP (Maya Early to Late Preclassic). From 2300-1100 BP (Late Preclassic to Classic Periods), the landscape aggraded from five main mechanisms: river flooding, climatic instability, accelerated erosion, ancient Maya landscape manipulation, and gypsum precipitation from a rise in a water table nearly saturated in calcium and sulfate ions. Evidence exists for two or three high magnitude floods, possibly driven by hurricanes. Moreover, lake-core and geophysical studies from the Petn Lakes region have shown high rates of deposition of silicate clays ('Maya Clays') starting and peaking during the Maya Preclassic and continuing to be high through the Late Classic. The main driver on upland karst depressions, the Petn lakes, upland valleys, and fans was accelerated soil erosion, but water table rise, probably driven by sea-level rise, was the main driver on the wetlands of the coastal plain because the aggraded sediments here are dominantly composed of gypsum, precipitated from the groundwater. This latter mechanism represents a little recognized mechanism of aggradation over a large region. These large scale environmental changes occurred during periods of intensive ancient Maya land use and climatic instability, both of which may have contributed to erosion by increasing runoff. Despite these geomorphic changes, ancient Maya farmers adapted in several key cases.

Beach, Timothy; Luzzadder-Beach, Sheryl; Dunning, Nicholas; Cook, Duncan

2008-10-01

300

Dissolved gaseous mercury concentrations and mercury volatilization in a frozen freshwater fluvial lake.  

PubMed

In situ mesocosm experiments were performed to examine dissolved gaseous mercury (DGM), mercury volatilization, and sediment interactions in a frozen freshwater fluvial lake (Lake St. Louis, Beauharnois, QC). Two large in situ mesocosm cylinders, one open-bottomed and one close-bottomed (no sediment diffusion), were used to isolate the water column and minimize advection. Mercury volatilization over the closed-bottom mesocosm did not display a diurnal pattern and was low (mean = -0.02 ng m(-2) h(-1), SD = 0.28, n=71). Mercury volatilization over the open-bottom mesocosm was also low (mean = 0.24 ng m(-2) h(-1), SD = 0.08, n=96) however a diurnal pattern was observed. Low and constant concentrations of DGM were observed in surface water in both the open-bottomed and close-bottomed mesocosms (combined mean = 27.6 pg L(-1), SD = 7.2, n=26). Mercury volatilization was significantly correlated with solar radiation in both the close-bottomed (Pearson correlation = 0.33, significance = 0.005) and open-bottomed (Pearson correlation = 0.52, significance = 0.001) mesocosms. However, DGM and mercury volatilization were not significantly correlated (at the 95% level) in either of the mesocosms (significance = 0.09 in the closed mesocosm and significance = 0.9 in the open mesocosm). DGM concentrations decreased with depth (from 62 to 30 pg L(-1)) in the close-bottomed mesocosm but increased with depth (from 30 to 70 pg L(-1)) in the open-bottomed mesocosm suggesting a sediment source. DGM concentrations were found to be high in samples of ice melt (mean 73.6 pg L(-1), SD = 18.9, n=6) and snowmelt (mean 368.2 pg L(-1), SD = 115.8, n=4). These results suggest that sediment diffusion of mercury and melting snow and ice are important to DGM dynamics in frozen Lake St. Louis. These processes may also explain the lack of significant correlations observed in the DGM and mercury volatilization data. PMID:18754358

O'Driscoll, N J; Poissant, L; Canrio, J; Lean, D R S

2008-07-15

301

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

NASA Astrophysics Data System (ADS)

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.

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

2008-02-01

302

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

303

Petrography and provenance of the Early Permian Fluvial Warchha Sandstone, Salt Range, Pakistan  

NASA Astrophysics Data System (ADS)

The Warchha Sandstone of the Salt Range of Pakistan is a continental succession that accumulated as part of a meandering, fluvial system during Early Permian times. Several fining-upward depositional cycles are developed, each of which is composed of conglomerate, cross-bedded sandstone and, in their upper parts, bioturbated siltstone and claystone units with distinctive desiccation cracks and carbonate concretions. Clast lithologies are mainly of plutonic and low-grade metamorphic origin, with an additional minor sedimentary component. Textural properties of the sandstone are fine- to coarse-grained, poorly to moderately sorted, sub-angular to sub-rounded, and with generally loose packing. Based on modal analyses, the sandstone is dominantly a feldspathoquartzose (arkose to sub-arkose). Detrital constituents are mainly composed of monocrystalline quartz, feldspars (more K-feldspar than plagioclase) and various types of lithic clasts. XRD and SEM studies indicate that kaolinite is the dominant clay mineral and that it occurs as both allogenic and authigenic forms. However, illite, illite-smectite mixed layer, smectite and chlorite are also recognised in both pores and fractures. Much of the kaolinite was likely derived by the severe chemical weathering of previously deposited basement rocks under the influence of a hot and humid climate. Transported residual clays deposited as part of the matrix of the Warchha Sandstone show coherent links with the sandstone petrofacies, thereby indicating the same likely origin. Illite, smectite and chlorite mainly occur as detrital minerals and as alteration products of weathered acidic igneous and metamorphic rocks. Based primarily on fabric relationship, the sequence of cement formation in the Warchha Sandstone is clay (generally kaolinite), iron oxide, calcareous and siliceous material, before iron-rich illite and occasional mixed layer smectite-illite and rare chlorite. Both petrographic analysis and field characteristics of the sandstone indicate that the source areas were characterised by uplift of a moderate to high relief continental block that was weathered under the influence of hot and humid climatic conditions. The rocks weathered from the source areas included primary granites and gneisses, together with metamorphic basement rocks and minor amounts of sedimentary rocks. Regional palaeogeographic reconstructions indicate that much of the Warchha Sandstone detritus was derived from the Aravalli and Malani ranges and surrounding areas of the Indian Craton to the south and southeast, before being transported to and deposited within the Salt Range region under the influence of a semi-arid to arid climatic regime.

Ghazi, Shahid; Mountney, Nigel P.

304

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

305

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

NASA Astrophysics Data System (ADS)

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.

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

2008-12-01

306

Previso de Demanda de Energia Eltrica Utilizando Redes Neurais Artificiais e Support Vector Regression  

Microsoft Academic Search

This paper describes a short time electrical energy demand forecast system using two different techniques of Artificial Intelligence: Recurrent Artificial Neural Networks and Support Vector Regression. A brief analysis of the demand over the electrical energy network connection points is also done. Resumo. Este artigo descreve um sistema de previso da demanda de energia a curto prazo utilizando duas tcnicas

Gabriel I. S. Ruas; Ticiano A. C. Bragatto; Marcus V. Lamar; Alexandre R. Aoki; Silvio Michel de Rocco

307

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)

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.

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

2014-11-01

308

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)

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.

Paredes, Jos Matildo; Foix, Nicols; Colombo Piol, Ferrn; Nillni, Adriana; Allard, Jos O.; Marquillas, Rosa A.

2007-11-01

309

Sequence stratigraphic-structural analysis of the East Midlands Carboniferous oil field, UK: Implications for fluvial reservoir models  

SciTech Connect

The integration of seismic, well log and core data from, the Scampton North and Welton oil fields, Lincolnshire, UK, has enabled the development of a sequence stratigraphic-structural model for late Namurian and early Westphalian fluvial reservoirs. The tectonic and sequence stratigraphic setting is remarkably similar to that in the Southern North Sea which extends more than 250 km to the east. Closer onshore well spacing, supplemented with coal exploration borehole data, provides an excellent analogue for new Carboniferous Southern North Sea developments and prospects. The reservoirs comprise medium-grained, low sinuosity fluvial aggradational packages within a coal-bearing, fluvio-deltaic depositional environment. Although major active faults occur within the Namurian, tectonic activity had ceased by the start of the Westphalian which has a tramline-like appearance on seismic. The reservoirs are poorly interconnected as a consequence of small-scale faults and extensive shale baffles, which have resulted in considerable production problems, accentuated by an initial poor reservoir correlation. Palynology has proven to be highly imprecise, consequently, the use of seismic picks as chronostratigraphic markers combined with the coal stratigraphy from British Coal boreholes and the application of sequence stratigraphic, concepts has enabled a more precise reservoir correlation to be made.

Aitken, J.F.; Quirk, D.G. (Oxford Brookes Univ., Oxford (United Kingdom))

1996-01-01

310

Sequence stratigraphic-structural analysis of the East Midlands Carboniferous oil field, UK: Implications for fluvial reservoir models  

SciTech Connect

The integration of seismic, well log and core data from, the Scampton North and Welton oil fields, Lincolnshire, UK, has enabled the development of a sequence stratigraphic-structural model for late Namurian and early Westphalian fluvial reservoirs. The tectonic and sequence stratigraphic setting is remarkably similar to that in the Southern North Sea which extends more than 250 km to the east. Closer onshore well spacing, supplemented with coal exploration borehole data, provides an excellent analogue for new Carboniferous Southern North Sea developments and prospects. The reservoirs comprise medium-grained, low sinuosity fluvial aggradational packages within a coal-bearing, fluvio-deltaic depositional environment. Although major active faults occur within the Namurian, tectonic activity had ceased by the start of the Westphalian which has a tramline-like appearance on seismic. The reservoirs are poorly interconnected as a consequence of small-scale faults and extensive shale baffles, which have resulted in considerable production problems, accentuated by an initial poor reservoir correlation. Palynology has proven to be highly imprecise, consequently, the use of seismic picks as chronostratigraphic markers combined with the coal stratigraphy from British Coal boreholes and the application of sequence stratigraphic, concepts has enabled a more precise reservoir correlation to be made.

Aitken, J.F.; Quirk, D.G. [Oxford Brookes Univ., Oxford (United Kingdom)

1996-12-31

311

Multi-residues analysis of pre-emergence herbicides in fluvial sediments: application to the mid-Garonne River.  

PubMed

Contamination of man and ecosystems by pesticides has become a major environmental concern. Whereas many studies exist on contamination from agriculture, the effects of urban sources are usually omitted. Fluvial sediment is a complex matrix of pollutants but little is known of its recent herbicide content. This study proposes a method for a fast and reliable analysis of herbicides by employing the accelerated solvent extractor (ASE). The aim of the study is to show the impact of a major town (Toulouse) on the herbicide content in the river. In this study, three herbicide families (i.e.s-triazine, substituted ureas and anilides) were analysed in fluvial sediment fractions at 11 sampling sites along the mid-Garonne River and its tributaries. River water contamination by herbicides is minor, except for at three sites located in urban areas. Among the herbicidal families studied, urban and suburban areas are distinguished from rural areas and were found to be the most contaminated sites during the study period, a winter low-water event. The herbicide content of the coarse sediment fractions is about one third of that found in the fine fractions and usually ignored. The distribution of pesticide concentrations across the whole range of particle sizes was investigated to clarify the role of plant remains on the significant accumulation in the coarse fractions. PMID:17726563

Devault, Damien A; Merlina, Georges; Lim, Puy; Probst, Jean-Luc; Pinelli, Eric

2007-09-01

312

LES of atmospheric boundary layer flow over fluvial-like anisotropic topography with a dynamic surface drag model  

NASA Astrophysics Data System (ADS)

A dynamic surface drag model (A. & M. 2011, JFM 679, 288 - 314) is applied in LES of atmospheric boundary layer (ABL) flow over fractal-like topography where the height field exhibits power-law energy spectrum. Initially, the dynamic drag model was applied in LES of ABL flow over isotropic synthetic fractal-like roughness. Here we consider fluvial-like anisotropic landscapes. Two main cases are considered. The first is a fluvial-like topography built through numerical solution of the Kardar-Parisi-Zhang equation.ootnotetextThanks also to Profs. P. Passalacqua and F. Porte-Agel for providing KPZ solution fields. The second is a rescaled topography (Texas) map from the U.S. National Elevation Dataset. These landscapes are dominated by anisotropic modes that have emerged through geomorphological erosion processes. The dynamic model yields stable solutions even in these highly anisotropic cases: performance is strongest for cases where the LES grid- and test-filter width are within the landscape ``self-similar'' range. Weaknesses are reported for cases where spectral exponent changes with wavenumber, motivating the development of a scale-dependent version of the dynamic approach using two test-filters.

Anderson, William; Meneveau, Charles

2011-11-01

313

Research Opportunities for Studies of Contaminant Transport in Fluvial Systems at the TIMS Branch - Steed Pond System, Savannah River Site  

SciTech Connect

A workshop to identify the scientific issues associated with contamination in riparian, fluvial, and hyporheic systems was held in March 2003 at the Savannah River Site (SRS). The workshop examined the general scientific remediation challenges and research opportunities in such systems and on Tims Branch - Steed Pond, a specific uranium- and heavy-metal-contaminated riparian system at SRS. A diverse group of scientists representing a wide range of scientific disciplines came from academia, national laboratories, and research centers to develop recommendations for future ERSD research opportunities. There was agreement among the workshop participants that riparian, fluvial, and hyporheic systems represent a unique opportunity to advance science and to enable progress on DOE's environmental cleanup of contaminated sites. The participants at this workshop documented both the critical need and the great promise for research on hydrological and biogeochemical processes controlling contaminant transport and fate in contaminated surface and near-surface systems. The approach of the workshop was to assess the Tims Branch - Steed Pond system at the SRS as an appropriate site to identify research needs that support potential remediation strategies.

Looney, B.B.

2003-08-13

314

Progress in faunal correlation of Late Cenozoic fluvial sequences 2000 4: the report of the IGCP 449 biostratigraphy subgroup  

NASA Astrophysics Data System (ADS)

Vertebrate and invertebrate faunal biostratigraphy is a well-tested method for establishing relative chronologies for fluviatile sequences that has proved useful in many parts of the world. The robust bones and teeth of large mammals are commonly found in fluviatile deposits, whereas small vertebrates can be readily recovered through systematic sieving of calcareous sediments, as can molluscs, the other major faunal group that has been used for biostratigraphical analysis of fluvial sequences. Because of their rapid and quantifiable rates of evolution, extinction, body mass change and dispersal during the Late Cenozoic, mammals are especially useful for ordering the fragmentary terrestrial sequence of interglacials and glacials, and proposing correlation with the global marine climatostratigraphic record. Other groups (e.g. reptiles and amphibians, ostracods) are as yet only in the initial stages of development as a dating tool, whereas some (e.g. fish, birds) still require substantial development in order to fully explore their utility. As part of IGCP 449, vertebrate and molluscan assemblages have made important contributions to datasets from a number of areas, notably northern France, central Germany, the Czech Republic and the Ukraine. Further south, mammalian assemblages have proved useful in separating discrete periods of climatic change in Iberia and Syria. At greater distances from the core area of fluvial biostratigraphical archives, significant contributions have come from South America (Uruguay River), South Africa (Vaal) and Australia (Riverine Plain and Lake Eyre drainage basin).

Schreve, D. C.; Keen, D. H.; Limondin-Lozouet, N.; Auguste, P.; Santisteban, Juan I.; Ubilla, M.; Matoshko, A.; Bridgland, D. R.; Westaway, R.

2007-11-01

315

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

SciTech Connect

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.

M. Lee Allison

1997-03-01

316

Volcanic or Fluvial Channels on Ascraeus Mons: Focus on the Source Area of Sinuous Channels on the Southeast Rift Apron  

NASA Technical Reports Server (NTRS)

Deciphering the Mars water history is important to understanding the planet's geological evolution and whether it could have sustained life. Channel features on Mars, such as the features documented in Kasei Valles, are generally accepted as evidence for water flowing over the Mars surface in the past [1]. However, not all channels are the product of fluvial processes and many can be interpreted as having a volcanic origin [2]. This research involves studying channel features on the flanks of the Ascraeus Mons volcano, which is a part of the Tharsis province. Numerous sinuous channels exist on the rift apron of Ascraeus Mons and they have been interpreted as either fluvial [3] or volcanic [4,5]. The channels originate from pits and linear depressions and extend for many 100 s of km downslope. Mapping the proximal to distal morphology of the complete channel and determining its relationship with other features on the apron provides evidence for the processes of formation and their relative temporal relationships. This study focused on sinuous channels located on the south-east part of the Ascraeus rift apron (Fig. 1). Observations of possible analogous features on Hawaii are used to provide insights into the processes of formation of the Mars features.

Signorella, Julia D.; deWet, A.; Bleacher, J. E.; Collins, A.; Schierl, Z. P.; Schwans, B.

2012-01-01

317

Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in frio fluvial-deltaic sandstone reservoirs at South Texas. Annual report, October 1994--October 1995  

SciTech Connect

The Frio Fluvial-Deltaic Sandstone oil play of South Texas has produced nearly 1 billion barrels of oil, yet it still contains about 1.6 billion barrels of unrecovered mobile oil and nearly the same amount of residual oil resources. Interwell-scale geologic facise models of Frio Fluvial-deltaic reservoirs are being combined with engineering assessments and geophysical evaluations in order to determine the controls that these characteristics exert on the location and volume or unrecovered mobile and residual oil. Progress in the third year centered on technology transfer. An overview of project tasks is presented.

Holtz, M.; Knox, P.; McRae, L. [and others

1996-02-01

318

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

319

Human impact on fluvial sediments: distinguishing regional and local sources of heavy metals contamination  

NASA Astrophysics Data System (ADS)

Industrial pollution can provide a useful tool to study spatiotemporal distribution of modern floodplain sediments, trace their provenance, and allow their dating. Regional contamination of southern Moravia (the south-eastern part of the Czech Republic) by heavy metals during the 20th century was determined in fluvial sediments of the Morava River by means of enrichment factors. The influence of local sources and sampling sites heterogeneity were studied in overbank fines with different lithology and facies. For this purpose, samples were obtained from hand-drilled cores from regulated channel banks, with well-defined local sources of contamination (factories in Zln and Otrokovice) and also from near naturally inundated floodplains in two nature protected areas (at 30 km distance). The analyses were performed by X-ray fluorescence spectroscopy (ED XRF), ICP MS (EDXRF samples calibration, 206Pb/207Pb ratio), magnetic susceptibility, cation exchange capacity (CEC), and 137Cs and 210Pb activities. Enrichment factors (EF) of heavy metals (Pb, Zn, Cu and Cr) and magnetic susceptibility of overbank fines in near-naturally (near annually) inundated areas allowed us to reconstruct historical contamination by heavy metals in the entire study area independently on lithofacies. Measured lithological background values were then used for calculation of EFs in the channel sediments and in floodplain sediments deposited within narrow part of a former floodplain which is now reduced to about one quarter of its original width by flood defences. Sediments from regulated channel banks were found stratigraphically and lithologically "erratic", unreliable for quantification of regional contamination due to a high variability of sedimentary environment. On the other hand, these sediments are very sensitive to the nearby local sources of heavy metals. For a practical work one must first choose whether large scale, i.e. a really averaged regional contamination should be reconstructed, or whether more or less qualitative information on local point sources is searched for. The profiles from regulated river reaches are highly prone to local sources and due to the stratigraphic chaos and post-depositional mobilization of heavy metals, which we revealed using 206Pb/207Pb ratio; such profiles were further excluded from an evaluation of regional contamination. Overbank fines in the study area (middle and lower reach of the Morava) are only weakly but whole-regionally contaminated (maximal EFs are 1.3-2 for Pb and Zn, 1.2-1.7 for Cu, 1.1-1.2 for Cr and 2-4 for magnetic susceptibility). Regulated river channel sediments, which reflect the actual contamination from local sources, produced apparent EFs ranging from 0.3 to 15 for heavy metals and 0.4-21 for MS, with the highest values obtained downstream from the most relevant point source in the study area, shoe-making and related chemical industry in Zln and Otrokovice.

Novakova, T.; Matys Grygar, T.; Bbek, O.; Fam?ra, M.; Mihaljevi?, M.; Strnad, L.

2012-04-01

320

The distribution and fluvial redistribution of soil organic carbon in semiarid rangelands  

NASA Astrophysics Data System (ADS)

Compared to other terrestrial biomes, the carbon dynamics of drylands have attracted relatively little attention, perhaps due to their characteristically low primary productivity, low soil organic carbon (OC) contents and slow OC turnover rates. However, covering approximately 40% of the land surface, drylands represent a significant component of the global terrestrial carbon sink. Our study examines the distribution and fluvial redistribution of particulate-associated OC over a dynamic grass to shrub ecotone in semiarid central New Mexico, USA. Surface soil (0-0.05 m) samples from beneath different vegetation covers across the ecotone were collected and physically fractionated by density (>1 g ml) and particle size (one phi intervals from <0.0625 to >4 mm, with no deliberate dispersion of aggregates). There were significant (P<0.05) differences in OC concentration between different particle-size fractions, with peaks in the silt-clay (<0.0625 mm) fraction, and, unexpectedly, in the three coarse-medium sand (2-1, 1-0.5, and 0.5-0.25 mm) fractions. As soil erosion by runoff is particle size-selective, this suggests estimating erosional carbon fluxes as a function of total sediment flux may be overly simplistic. Given that many soil erosion models already explicitly consider the transport of several particle size classes, we believe that the results presented here justify the particle-size variant parameterisation of OC concentration, which we are currently working to implement. Importantly, both of the coarsest (>4 and 4-2 mm) fractions had OC concentrations comparable to the <2 mm average, attributed to the aggradation of finer primary particles which suggests that, in dryland soils at least, the current practice of ignoring the >2 mm fraction may underestimate the magnitude of the soil OC sink. In addition to topsoil characterisation, we monitored natural erosion events from four 300 m2 runoff plots over four monsoon seasons, capturing all eroded sediment which was fractionated as detailed above. Substantial variability in bulk sediment OC enrichment between rainstorm events and between monsoon seasons demonstrates the need for multi-year studies to understand these ecohydrological systems. Intriguingly, average OC enrichment increases substantially as shrub domination increases. Historically, many studies have attributed whole-sediment OC enrichment to changes in particle-size distribution, on the basis of strong correlations between particle-size distributions and whole-sediment OC concentration enrichment. However, our results demonstrate substantial OC enrichment within all particle-size fractions, particularly in fine sand fractions, suggesting that this perceptual model is incomplete. We argue that advancing our understanding of OC redistribution by erosion requires detailed mechanistic examination of transport processes, in conjunction with numerical simulations to address the challenges of upscaling such process understanding.

Cunliffe, Andrew; Puttock, Alan; Anderson, Karen; Brazier, Richard

2014-05-01

321

Fluvial Bank Erosion in the Meandering River Asker, UK: Insights from Computational Fluid Dynamics (CFD) Modelling  

NASA Astrophysics Data System (ADS)

River bank erosion often significantly contributes to the catchment sediment yield. Knowledge of the rates & controls on bank erosion events is therefore important in understanding sediment flux. In recent years progress has been made in understanding processes controlling large-scale mass failure (MF) of stream banks, but less attention has been paid to the role that direct fluvial erosion (FE) plays in bank retreat. This is an important omission, not only because FE is a significant process in its own right, but because FE also often triggers mass failure. FE models are typically of the form: E = k(? - ? c)b where E is the bank erosion rate, ? is the applied fluid shear stress, ? c is the critical stress for entrainment of the bank material, k is an empirically-derived erodibility parameter, and b is an empirically-derived exponent, often assumed to be close to unity. To apply this model, accurate observations of applied fluid stresses, FE rates & bank erodibility are required. Recent developments in bank erosion monitoring technology [e.g. Lawler, 1993], and in the quantification of the bank erodibility parameters k and ? c using jet-testing devices [e.g. Hanson and Simon, 2001; Dapporto, 2001], offer the means of determining FE rates and bank erodibility. Nevertheless, the problem of collecting the high-resolution spatially-distributed data needed to characterise near-bank fluid stresses remains. One possible solution is to use Computational Fluid Dynamics (CFD) models as a substitute for empirical data. CFD simulations potentially offer a means of acquiring near-bank, distributed, boundary shear stress data at very high spatial resolution. In contrast, empirical data sets of comparable spatial extent and resolution are very difficult to obtain, particularly during the large (competent) flows of interest here. The critical question is therefore whether CFD-derived data are sufficiently accurate for this purpose. Herein we evaluate a series of 3-dimensional CFD simulations for a (200 m long) meander loop on the River Asker at Bridport in southern England. CFD models under specific steady (peak) flow conditions were developed using FLUENT, with peak flow discharge estimates obtained from an adjacent gauging station. The geometry of each model was specified using DEMs of the channel created from high-resolution tacheometric surveys of the study reach, with water surface elevation defined using a network of crest gauges spaced at 20 m intervals along the reach. Zero slip boundary conditions were defined at all sidewall nodes and initial flow velocity vectors at all nodes at the upstream inlet were estimated with reference to 3D flow velocity data acquired using Acoustic Doppler Velocimetry (ADV) at this location. Simulated flow fields for the extent of the study reach were then evaluated by comparing simulated and observed surface velocity vectors, the latter being derived from Particle Image Velocimetry (PIV), supplemented by ADV data in selected (accessible) locations. Finally, we use the near-bank boundary shear stress data obtained from the CFD models to develop insight into the nature and effectiveness of FE processes within the study reach.

Darby, S. E.; Rinaldi, M.; Rossi Romanelli, L.; Spyropoulos, E.

2003-12-01

322

Determinao eletroanaltica de nitrofurantona (NFT) em frmaco e em fluido biolgico utilizando eletrodo de diamante dopado com boro.  

E-print Network

??Este trabalho apresenta o estudo da quantificao de nitrofurantoina (NFT) utilizando os filmes de diamante dopados com boro como material eletrdico. Estudos preliminares utilizando voltametria (more)

Rafael Ribeiro Portela

2008-01-01

323

Testing the Late Noachian Icy Highlands Model: Geological Observations, Processes and Origin of Fluvial and Lacustrine Features.  

NASA Astrophysics Data System (ADS)

A new reconstruction of the Late Noachian Mars atmosphere and climate shows atmosphere-surface thermal coupling and an adiabatic cooling effect producing preferential distribution of snow and ice in the highlands. In this Late Noachian Icy Highlands (LNIH) scenario, snow and ice accumulate in the south circumpolar region and in the higher altitudes of the southern uplands, but the mean annual temperature is everywhere below freezing. How can the abundant evidence for water-related fluvial and lacustrine activity (valley networks, VN; open-basin lakes, OBL; closed-basin lakes; CBL) be reconciled with the icy highlands model? We investigate the nature of geologic processes operating in the icy highlands and use the Antarctic McMurdo Dry Valleys (MDV) as guidance in understanding and assessing how melting might be taking place. In the MDV, mean annual temperatures (MAT) are well below freezing. This results in a thick regional permafrost layer, the presence of an ice-table at shallow depths, and an overlying dry active layer. This configuration produces a perched aquifer and a horizontally stratified hydrologic system, where any melting results in local saturation of the dry active layer and channelized flow on top of the ice table. Top-down melting results in the dominance of lateral water transport, in contrast to temperate climates with vertical infiltration and transport to the groundwater table. Despite subzero MAT, MDV peak seasonal and peak daytime temperatures can exceed 273K and have a strong influence on the melting of available water ice. We present maps of the predicted distribution of LNIH snow and ice, compare these to the distribution of VN, OBL and CBL, and assess how top-down and bottom-up melting processes might explain the formation of these features in an otherwise cold and icy LN Mars. We assess the global near-surface water budget, analyze thickness estimates to distinguish areas of cold-based and wet-based glaciation, analyze the state of the ice cover and its susceptibility to melting and runoff, and describe top-down melting and fluvial channel formation processes in a LNIH environment. We find that: 1) episodic top-down melting of the LNIH is a robust mechanism to produce the observed fluvial and lacustrine features; 2) the characteristics and distribution of features in the Dorsa Argentea Formation are consistent with an extensive circum-polar ice cap during LNIH time; and 3) the nature of preserved LN impact craters is consistent with impact cratering processes in the LNIH environment. 393 words.

Head, James; Wordsworth, Robin; Forget, Francis; Madeleine, Jean-Baptiste; Halvey, Italy

2014-05-01

324

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

Microsoft Academic Search

The mating, egg-laying, and larval development of tailed frogs occur in dynamic mountain streams. During the lengthy (up to 5years) 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

Linda Dupuis; Pierre Friele

2006-01-01

325

Critical Evaluation of How the Rosgen Classification and Associated "Natural Channel Design" Methods Fail to Integrate and Quantify Fluvial Processes and Channel Response  

Technology Transfer Automated Retrieval System (TEKTRAN)

Over the past 10 years the Rosgen classification system and its associated methods of natural channel design have become synonymous to some with the term stream restoration and the science of fluvial geomorphology. Since the mid 1990s, this classification approach has become widely adopted by go...

326

Changes of bedload characteristics along the Marsyandi River (central Nepal): Implications for understanding hillslope sediment supply, sediment load evolution along fluvial networks, and denudation in active orogenic belts  

Microsoft Academic Search

Understanding and quantifying fluvial transport and bedrock abrasion process - es have become major concerns in modeling landform response to tectonic and cli- matic forcing. Recent theoretical and experimental investigations have in particular stressed the importance of sediment supply and size in controlling bedrock incision rate. Many studies on the downstream evolution of pebble size have focused on unrav- eling

Mikal Attal; Jrme Lav

2006-01-01

327

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

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

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

1996-01-01

328

Human and climatic impact on the environment as derived from colluvial, fluvial and lacustrine archivesexamples from the Bronze Age to the Migration period, Germany  

Microsoft Academic Search

Investigation of colluvial, fluvial and lacustrine sediment archives from 12 sites in Germany for the last ca 5000 years demonstrates that there is no synchronous development of the cultural landscape. This can only be explained, if climate is not the dominating control mechanism. However, to a certain degree there is a climatic influence, like during the slight climatic deteriorations immediately

Bernd Zolitschka; Karl-Ernst Behre; Jrgen Schneider

2003-01-01

329

Strontium isotopic record of signatures of Holocene fluvial sediments in the Loire valley, France Hydrology and Earth System Sciences, 6(5), 849858 (2002) EGS  

E-print Network

Strontium isotopic record of signatures of Holocene fluvial sediments in the Loire valley, France 849 Hydrology and Earth System Sciences, 6(5), 849­858 (2002) © EGS Strontium isotopic record for corresponding author: p.negrel@brgm.fr Abstract The distribution of Sr contents and isotopes of strontium Sr

Paris-Sud XI, Université de

330

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

SciTech Connect

The main objective of the Port Neches Project was to determine the feasibility and producibility of CO2 miscible flooding techniques enhanced with horizontal drilling applied to a Fluvial Dominated Deltaic reservoir. The second was to disseminate the knowledge gained through established Technology Transfer mechanisms to support DOE's programmatic objectives of increasing domestic oil production and reducing abandonment of oil fields.

Bou-Mikael, Sami

2002-02-05

331

Journal of Coastal Research 25 1 189208 West Palm Beach, Florida January 2009 Potential Effects of Runoff, Fluvial Sediment, and Nutrient  

E-print Network

to improved understanding of this problem, the potential relation between river sediment and nutrient streptococcus concentrations in many Puerto Rico rivers are near or above regulatory limits. Unlike sediment of Runoff, Fluvial Sediment, and Nutrient Discharges on the Coral Reefs of Puerto Rico Matthew C. Larsen

332

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

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.

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

1993-02-01

333

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

SciTech Connect

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.

Bou-Mikael, Sami

2002-02-05

334

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

PubMed

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

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

2009-07-01

335

Early Mars was wet but not warm: Erosion, fluvial features, liquid water habitats, and life below freezing  

NASA Technical Reports Server (NTRS)

There is considerable evidence that Mars had liquid water early in its history and possibly at recurrent interval. It has generally been assumed that this implied that the climate was warmer as a result of a thicker CO2 atmosphere than at the present. However, recent models suggest that Mars may have had a thick atmosphere but may not have experienced mean annual temperatures above freezing. In this paper we report on models of liquid water formation and maintenance under temperatures well below freezing. Our studies are based on work in the north and south polar regions of Earth. Our results suggest that early Mars did have a thick atmosphere but precipitation and hence erosion was rare. Transient liquid water, formed under temperature extremes and maintained under thick ice covers, could account for the observed fluvial features. The main difference between the present climate and the early climate was that the total surface pressure was well above the triple point of water.

Mckay, C. P.; Davis, W. L.

1993-01-01

336

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

SciTech Connect

The objective of the Ferron Sandstone project was to develop a comprehensive, interdisciplinary, quantitative characterization f fluvial-deltaic reservoir to allow realistic interwell 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 was collected. Both new and existing data was 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.

Chidsey Jr., Thomas C.

2001-10-31

337

Plant Wax Biomarkers in Fluvial-Lacustrine Sediments from the Omo-Turkana and Awash Basins in Eastern Africa  

NASA Astrophysics Data System (ADS)

Stable isotope analysis of terrestrial plant biomarkers has emerged over the past decade as a powerful tool for reconstructing vegetation and hydroclimate from lacustrine and marine sediments in eastern Africa. Presently, no comprehensive biomarker records exist from late Miocene to late Pleistocene terrestrial sediments in eastern Africa. Fluvial-lacustrine deposits in the Omo-Turkana and Awash Basins located in Kenya and Ethiopia host a diverse faunal record that is rich in hominin taxa. Biomarker records from these deposits could provide continuous, high-resolution terrestrial paleoclimate records that would enable direct comparison of climate and biotic change through time, fill gaps in the discontinuous isotopic record from paleosol carbonates, and compliment existing biomarkers records from marine sediments. The heterogeneity of fluvial-lacustrine deposits compared to marine and continuous lacustrine deposits requires rigorous assessment of biomarker preservation and abundance prior to isotopic analysis. We analyzed fluvio-lacustrine sediments from the Sagantole, Hadar, and Busidima Fms. in the Awash Basin and the Shungura and Nachukui Fms. in the Omo-Turkana Basin to assess the feasibility of generating continuous isotopic records of vegetation and hydroclimate from these basins. We measured the distribution, abundance, and where possible, preliminary ?D and ?13C values of n-alkanes and n-alkanoic acids extracted from sediments. The carbon preference index (CPI) serves as an indicator for biomarker preservation. The CPI for long-chain n-alkane and n-alkanoic acids is generally >2, suggesting suitable biomarker preservation in most cases. Abundances vary significantly in both n-alkanes and n-alkanoic acids, with higher concentrations in lacustrine versus fluvial samples. About two-thirds of the samples have concentrations sufficient for ?D analysis given sample size (<200 g) and current analytical requirements, whereas ?13C analysis is feasible for a majority of samples because of the smaller sample requirements. Preliminary results show a range of ca. 95 in ?D values. In many samples, a large unresolved complex mixture (UCM) is present in the aliphatic fraction. The UCM co-elutes with short and mid-chain n-alkanes and can interfere with isotopic measurement of the long chain n-alkanes unless removed via urea adduction or molecular sieve. A promising application of paleosol biomarkers is combining biomarker ?D values with pedogenic carbonate clumped isotope paleothermometry and ?18O values from the same sample or within the same soil unit. We are exploring how ?D, ?18O, and clumped isotope data from these isotope systems can be used to evaluate aridity, changes in moisture source, or changes in precipitation in past environments. Overall, we find fluvial-lacustrine deposits are promising biomarker archives, but caution that careful screening and assessment is required.

Uno, K. T.; Polissar, P. J.; Bonnefille, R.; Brown, F.; Feibel, C. S.; Kahle, E.; Levin, N.; Lepre, C. J.; deMenocal, P. B.

2013-12-01

338

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

PubMed Central

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, 0.56.2 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

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

2012-01-01

339

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

SciTech Connect

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.

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

1995-06-01

340

The variogram and the simple kriging estimator: Useful tools to complement lithologic correlation in a complex fluvial depositional environment  

SciTech Connect

Three dimensional grid estimation has been combined with an interpretive model of fluvial deposition for correlating low permeability zones in the shallow subsurface. Improvement in correlation reliability was realized by combining hand drawn interpretive cross-sections (spotting local trends in grain size, CPT log signature, etc.) with cross-section maps of the geostatistical grid model. The site is a military installation where soil contamination is being mapped and quantified using three dimensional modeling techniques. The subsurface is a complex fluvial depositional environment with intermittent bedrock highs and more frequent calcite and Calcium/Iron related cementation. Hence, the problem of lithologic correlation occurred where the drillhole spacing became wider than the channel belt width or cemented materials prevented detailed sampling. The goals of the sampling and analysis plan called for sampling within the first continuous silt or clay unit in order to quantify the zone of greatest contaminant retention on its downward migratory path. This paper will describe a three dimensional correlation technique which employs geostatistical analysis of CPT hole data specifically coded by permeability indicator thresholds. The process yielded variogram ranges applied to a simple kriging estimator on a 3-dimensional grid block. Estimates of clay probability are then provided as output and overlaid with the geologists cross section interpretation. The marriage of these two tools was invaluable in that geostatistical estimates sometimes behaved contrary to the channel depositional process, while on the other hand, the geologists interpretation often failed to recognize data in the third dimension (i.e. off section CPT data).

Murphy, J. [IT Corp., Martinez, CA (United States)

1995-12-31

341

Channel morphology and bed-load yield in fluvial, formerly-glaciated headwater streams of the Columbia Mountains, Canada  

NASA Astrophysics Data System (ADS)

This study examines channel-reach morphology and bedload yield dynamics in relation to landscape structure and snowmelt hydrology in headwater streams of the Columbia Mountains, Canada. Data collection relies on field surveys and geographic information systems analysis in conjunction with a nested monitoring network of water discharge and bedload transfer. The landscape is characterized by subdued, formerly-glaciated upland topography in which the geomorphic significance of landslides and debris flows is negligible and fluvial processes prevail. While the spatial organization of channel morphology is chiefly controlled by glacially imposed local slope in conjunction with wood abundance and availability of glacigenic deposits, downstream patterns of the coarse grain-size fraction, bankfull width, bankfull depth, and stream power are all insensitive to systematic changes of local slope along the typically stepped long profiles. This is an indication that these alluvial systems have adjusted to the contemporary snowmelt-driven water and sediment transport regimes, and as such are able to compensate for the glacially-imposed boundary conditions. Bedload specific yield increases with drainage area suggesting that fluvial re-mobilization of glacial and paraglacial deposits dominate the sedimentary dynamics of basins as small as 2 km2. Stepwise multiple regression analysis shows that annual rates of sediment transfer are mainly controlled by the number of peak events over threshold discharge. During such events, repeated destabilization of channel bed armoring and re-mobilization of sediment temporarily stored behind LWD structures can generate bedload transport across the entire snowmelt season. In particular, channel morphology controls the variability of bedload response to hydrologic forcing. In the present case studies, we show that the observed spatial variability in annual bedload yield appears to be modulated by inter-basin differences in morphometric characteristics, among which slope aspect plays a critical part.

Green, K. C.; Brardinoni, F.; Alila, Y.

2013-04-01

342

The influence of a large anthropogenic sediment source on the fluvial geomorphology of the Knabena-Kvina rivers, Norway  

NASA Astrophysics Data System (ADS)

Molybdenum mining at Knaben discharged more than eight million tonnes of tailings into two lakes in the upstream end of the Knabena river, southern Norway, during the period 1918-1973. A dam was built downstream of the lakes in 1976 to stop the fluvial dispersion of tailings. Bulk samples were collected from the tailings pond ( n = 30), natural sediment sources ( n = 7), sandbars ( n = 98), and overbank sediments (0-25 cm depth, n = 79) along the 55-km river reach downstream of the mining area. In addition, overbank sediment samples of 1 cm thickness were collected at depth intervals of 1-5 cm in 19 vertical profiles ( n = 497). Sedimentological properties were recorded in 17 of the profiles. Chemical analysis (ICP-AES after hot nitric acid or aqua regia extraction) has shown that a minimum of 420000 tonnes of tailings with a median molybdenum content of 80 ppm are presently stored in the fluvial sediments. The major volumes are present in sandbars in a 6 km long, low-gradient reach that acts as a bedload trap under normal flood conditions. However, bedload may be flushed into the steeper reaches by repeated major events. On the floodplains, 14C-dating has shown that the average sedimentation rate in one profile has increased from 0.5 to 4.3 mm/year due to deposition of tailings. Since lateral channel instability has only been detected in a few locations, the floodplains are regarded as semi-permanent sinks for tailings. However, extreme floods that strip off vegetation or undercut the floodplains may increase the availability of tailings from these deposits. The results from the Knabena-Kvina rivers indicate that construction of weirs may stop the dispersion of bedload-sized contaminated sediments, while construction of dams may be necessary to trap contaminated sediments transported in suspension. In each case the benefit and disadvantages of such constructions must be evaluated according to the local conditions.

Langedal, Marianne

1997-05-01

343

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

NASA Astrophysics Data System (ADS)

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.

Penezic, Kristina; Kadereit, Annette; Thiemeyer, Heinrich

2013-04-01

344

Influence of growth faults on coastal fluvial systems: Examples from the late Miocene to Recent Mississippi River Delta  

NASA Astrophysics Data System (ADS)

The details of how fluvial systems respond to spatial changes in land-surface subsidence produced by active faulting remain incompletely understood. Here, we examine the degree to which the positioning of individual channels and channel-belts is affected by local maxima in subsidence associated with the hanging walls of growth faults. The channel forms and faults are imaged using a seismic volume covering 1400 km2 of Breton Sound and Barataria Bay in southern Louisiana, USA. We look at the consequences of interactions between channels, channel-belts, and faults in late Miocene to Recent strata. More than fifty individual channels that crossed the traces of active growth faults were examined. Of these channels, only three appear to have been redirected by the faults. There also appeared to be no systematic change in the cross-sectional geometries of channels or channel-belts associated with crossing a fault, though the orientation of the channel-belts appears to be more influenced by faulting than the orientation of individual channels. Seven out of ten mapped channel-belts appear to have been steered by growth faults. We propose that channel belts are more likely to be influenced by faults than individual channels because channel-belts are longer lived features, unlikely to shift their overall position before experiencing a discrete faulting event. In addition, the style of influence in the few cases where an individual channel is affected by a fault is different from that of larger systems. While downstream of a fault channel-belts generally become oriented perpendicular to fault strike, the individual channels are directed along the hanging wall of the fault, running parallel to the fault trace. We relate this to the ratio of the length-scale of fault rollover relative to the channel or channel-belt width. Fluvial-fault interactions with higher values for this ratio are more likely to be carried parallel to the fault trace than systems with lower ratio values.

Armstrong, Christopher; Mohrig, David; Hess, Thomas; George, Terra; Straub, Kyle M.

2014-03-01

345

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

SciTech Connect

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. 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 case-study area and (2) technology transfer. The Ivie Creek case-study evaluation work during the quarter focused on the two parasequence sets, the Kf-1 and Kf-2, in the lower Ferron Sandstone. This work included: (1) clinoform characterization, (2) parasequence characterization from elevation and isopach maps, and (3) three-dimensional facies modeling. Scaled photomosaic panels from the Ivie Creek amphitheater (south-facing outcrop belt) and Quitchupah Canyon (Fig. 1) provide a deterministic framework for two apparent-dip cross sections. These panels along with other photomosaic coverage and data from five drill holes, ten stratigraphic sections, and 22 permeability transacts (Fig. 1), acquired during two field seasons, provided the necessary information for this geologic evaluation and creation of the models to be used in reservoir simulations.

Allison, M.L.

1997-07-01

346

Sediment facies and Holocene deposition rate of near-coastal fluvial systems: An example from the Nobi Plain, Japan  

NASA Astrophysics Data System (ADS)

Floodplains are a major component of present near-coastal fluvial systems that have evolved in response to postglacial changes in climate and sea level. Knowledge of sedimentary facies and deposition rates on a centennial to millennial time scale is required for considering floodplain evolution. Two cores, AP1 and AP2, were acquired from an abandoned channel of the Ibi River and its natural levee on the Nobi Plain, central Japan. Sediment facies analysis, electrical conductivity, and radiocarbon dating of borehole samples showed that in both cores organic-rich dark gray floodbasin mud overlies deltaic deposits dating to after approximately 3200 years calibrated radiocarbon age (cal BP) in relation to delta progradation. The accumulation of floodbasin mud continued at the both sites until about 400 cal BP. Around 400 cal BP, the mud was eroded by the overlying channel sand and gravel at AP1 and was covered by fine-grained natural levee deposits at AP2 with an abrupt contact. This timing is concordant with the historical record of avulsion of the Ibi River during the Keicho Era (AD 1596-1615). Averaged aggradation rates at the AP1 and AP2 sites were approximately 2.2 and 3.2 mm/yr, respectively. Faulting-related subsidence along the western edge of the plain has influenced these rates by creating accommodation. Averaged deposition rates differed greatly between the floodbasin and the levee, suggesting that rapid aggradation of the natural levee also occurred on a centennial to millennial scale. These empirical data may be useful for testing models of the architecture and evolution of near-coastal fluvial systems.

Hori, Kazuaki; Usami, Shogo; Ueda, Hiroki

2011-05-01

347

Explorando el costo-efectividad de instrumentos basados en el mercado para la mejora de la calidad del agua: una modelacin espacial econmico-ambiental  

Microsoft Academic Search

El uso agrcola de la tierra en cuencas costeras conduce a la contaminacin del agua y degradacin subsecuente de recursos costeros y marinos. Para asegurar el desarrollo econmico sostenible de las regiones costeras, es necesario balancear los beneficios marginales de la contaminacin (agrcola) del agua con los costos marginales asociados a la degradacin de los recursos costeros y marinos. La

Peter C. Roebeling; Martijn E. van Grieken

2009-01-01

348

PROYECTO SOSTAUGA: EL USO SOSTENIBLE DEL AGUA Y SU RELACIN CON EL TERRITORIO EN EL CAMPUS DE ELVIA Y DE LA ZAPATEIRA DE LA UNIVERSIDAD DE A CORUA_UDC  

E-print Network

aprovechamiento de las aguas residuales urbanas tanto en tiempo seco como de lluvia,1 PROYECTO SOSTAUGA: EL USO SOSTENIBLE DEL AGUA Y SU RELACI?N CON EL TERRITORIO EN EL CAMPUS DE elemento agua y sus ecosistemas asociados. Preservar y potenciar un elemento clave del patrimonio socio

Fraguela, Basilio B.

349

El Instituto de Ciencias del Mar y Limnologa, organiza el "Da Mundial del Agua 2012", un evento de Puertas Abiertas para celebrar "El Agua y la seguridad alimentara" tema  

E-print Network

El Instituto de Ciencias del Mar y Limnología, organiza el "Día Mundial del Agua 2012", un evento AYALA-CASTA?ARES" INSTITUTO DE CIENCIAS DEL MAR Y LIMNOLOGÍA, UNAM PROGRAMA 09:30 - 09:35 Inauguración y

Islas, León

350

Unmanned aerial monitoring of fluvial changes in the vicinity of selected gauges of the Local System for Flood Monitoring in Klodzko County, SW Poland  

NASA Astrophysics Data System (ADS)

Only high resolution spatial data enable precise measurements of various morphometric characteristics of river channels and ensure meaningful effects of research into fluvial changes. Using ground-based measurement tools is time-consuming and expensive. Traditional photogrammetry often does not reach a desired resolution, and the technology is cost effective only for the large-area coverage. The present research introduces potentials of UAV (Unmanned Aerial Vehicle) for monitoring fluvial changes. Observations were carried out with the ultralight UAV swinglet CAM produced by senseFly. This lightweight (0,5 kg), small (wingspan: 80 cm) aircraft allowed frequent (with approximately monthly sampling resolution) and low-cost missions. Three hydrologic gauges, the surroundings of which were the target of series of photos taken by camera placed in airplane frame, belong to the Local System for Flood Monitoring in K?odzko County (SW Poland). The only way of obtaining reliable results is an appropriate image rectification, in order to measure morphometric characteristics of terrain, free of geometrical deformations induced by the topographical relief, the tilt of the camera axis and the distortion of the optics. Commercially available software for the production of digital orthophotos and digital surface models (DSMs) from a range of uncalibrated oblique and vertical aerial images was successfully used to achieve this aim. As a result of completing the above procedure 9 orthophotos were generated (one for each of 3 study areas during 3 missions). For extraction of terrain parameters, a DSM was produced as a result of bundle block adjustment. Both products reached ultra-high resolution of 4cm/px. Various fluvial forms were classified and recognized, and a few time series of maps from each study area were compared in order to detect potential changes within the fluvial system. We inferred on the origins of the short-term responses of fluvial systems, and such an inference was feasible due to the analysis of metrological and hydrological data recorded by the Local System for Flood Monitoring in K?odzko County. Orthophotos and DSMs, generated from imagery obtained by UAV, show high accuracy of results and are suitable for measuring fluvial changes. This approach moves beyond current restrictions of traditional data collecting, due to its unprecedented spatial and temporal resolution and low cost of application.

Jeziorska, Justyna; Witek, Matylda; Niedzielski, Tomasz

2013-04-01

351

Trachytic pyroclastics from Agua de Pau volcano, Sao Miguel, Azores: evolution of a magma body over 4,000 years  

Microsoft Academic Search

The Recent stratigraphy of Sao Miguel records large numbers of trachytic pyroclastic deposits produced by sub-plinian to plinian eruptions. Tephrochronological studies by Walker and Croasdale (1971) and Booth et al. (1978) have shown that in the last 5,000 years there have been five such eruptions from the caldera of Agua de Pau, one of the three active stratovolcanoes on Sao

Michael Storey

1982-01-01

352

Late Pleistocene-Early Holocene climatic shift recorded by the paleomorphology of the Lower Tisza fluvial system, Hungary  

NASA Astrophysics Data System (ADS)

Palaeohydrological record coupled with geochronology can serve as key tools for reconstructing past environmental and climatic change. The alluvial plains of the Carpathian Basin are hosting numerous generations of paleochannels which developed in response to highly varying water and sediment discharges. Our investigations focused on the Lower Tisza Basin where palaeomenaders remained recognisable only in a relatively narrow N-S belt along the Tisza river. The width and wavelength of these channels significantly exceed contemporary values even if compared to that of the Danube. Two major channel generations were investigated: one located on a higher level of the floodplain, having larger but more blurred pointbars and main channel, and another in the level of the present floodplain, having smaller but much fresher forms. The primary aim of the research is create the chronological framework of fluvial activity in the region and to determine palaeodischarges, thus to evaluate the trend and magnitude of climatic change. On the other hand the rate of morphological evolution is also assessed, which provides a more detailed insight to the environment in which the meanders were developing. The age and development rate of meanders were determined by the means of luminescence dating (OSL). 16 drillings were made to sample pointbar and channel sediments of two megameanders. Fluvial stratigraphy and sedimentological correlations were set up by laser grainsize analyis. Discharges were calculated on the basis of plaeohydrological equations, however by estimating palaeo cross-sectional area and slope more reasonable results were received. In all more than 30 sediment samples were measured by OSL. In numerous cases both their polymineral fine grain and quartz coarse grain fractions were also dated in order to assess the adequacy of bleaching during deposition, and the applicability of the more abundant fine grain sediments for dating purposes. Luminescence measurements show that coarse grain minimum ages are in a relatively good coincidence with fine grain ages, thus both types of sediments can be applied for OSL in this meandering system. The formation of the more elevated, larger meander was dated to the Blling-Allerd Interstadial (12-14 ka). The smaller meander started to evolve approx. 10 ka ago, suggesting that incision and the development of the present floodplain level took place during the shift from the Younger Dryas to the more moderate Holocene climate. Based on calculations, channel forming discharges were around 10 000 and 5 000 m3/s, respectively. The rate of lateral accretion was also very different. The older meander developed at a rate of 1 m/y, while this value could be three four times higher in case of the younger one. This refers either to much higher energies or less stabilised boundaries acting within the fluvial system in the Early Holocene.

Sipos, Gyrgy; Kiss, Tmea; Koroknai, Levente; Horvth, Zsolt; Dezs?, Jzsef

2010-05-01

353

Multi-storey calcrete profiles developed during the initial stages of the configuration of the Ebro Basin's exorrheic fluvial network  

NASA Astrophysics Data System (ADS)

Multi-storey calcrete profiles developed in the Quaternary on strath terraces of the Cinca and Alcanadre rivers, tributaries of the Ebro River in NE Spain. Two calcrete profiles (Tor 1 and Tor 2) near the village of El Tormillo show horizons with an arrangement that differs from that of commonly described calcrete profiles. Significant lateral changes occur in these profiles within a distance of less than 200 m, reflecting their pedofacies relationship. The Tor 1 profile on terrace Qt1 (the highest and oldest) consists of six horizons (from bottom to top): 1) coarse fluvial gravels; 2) mudstones with carbonate nodules; 3) a chalky horizon; 4) laminar horizons, including one peloidal horizon; 5) a multi-storey horizon formed of at least six minor sequences, each of which includes a lower detrital layer, a pisolithic horizon, and a thin discontinuous laminar horizon (these sequences indicate several cycles of brecciation and/or reworking); and 6) a topmost laminar and brecciated horizon also including reworked pisoliths. Some 200 m to the north of Tor 1, horizon 5 undergoes a lateral change to channel fill-deposits. The infill of the channels shows a fining-upwards sequence ranging from clasts of about 10 cm in diameter to red silts with sparse pebbles. All the clasts come from the underlying calcrete horizons. Laminar horizons are interbedded with the clastic channel deposits. The youngest calcrete profiles developed on terrace Qt3 of the Cinca River and on the Qp4 and Qp6 mantled pediment levels. All show relatively simple profiles composed mostly of lower horizons of coated gravels, with thin laminar horizons at the top. Most of the horizons, especially the laminar ones, show biogenic features such as alveolar septal structures, calcified filaments, biofilms, spherulites, micropores and needle-like calcite crystals. These features indicate the important role of vegetation in the formation of all the above profiles. The interbedding of clastic sediments and pisolithic horizons within the Tor 2 profile indicates several stages of stabilisation during profile formation. These sequences are an indication of the sedimentation, soil formation and reworking processes operating on the soil surface. The alternation of these processes is interpreted as the result of climate-vegetation changes. The channel-fills of Tor 2 indicate erosion and reworking of the hard laminar calcrete horizon. Both Tor 1 and Tor 2 are multi-storey profiles reflecting the complex sedimentation-erosion-pedogenesis relationships at the final stages of the development of its corresponding fluvial terrace. The study of these calcretes shows that these supposedly abandoned terraces continue to be active even though the fluvial network is entrenched. Both the pedofacies relationships and the complexity shown by Tor 1 and Tor 2 reflect the complex and unstable geomorphic setting in which these profiles developed. After the establishment of the exorrheic network, less complex calcrete profiles were produced in the lower terraces.

Melndez, Alfonso; Alonso-Zarza, Ana M.; Sancho, Carlos

2011-11-01

354

Fluvial terrain models produced with Structure-from-Motion and optical bathymetric mapping: Fit for the purpose of numerical modelling  

NASA Astrophysics Data System (ADS)

During the past decade, the advances in survey and sensor technology and three-dimensional morphologic analysis have been partially driven by the need for high resolution topography for physical and numerical fluvial modelling and have in return created new opportunities to investigate and model the structure and dynamics of fluvial systems. While the potential of such revolutionary survey technologies such as GPS, LiDAR, and terrestrial laser scanners have proven to produce high resolution fluvial terrain models, their high hardware and facility costs or labor intensive methods restrict data acquisition; thus limiting the extent and frequency of surveys. However, recent advances in computer vision and image analysis have led to the development of a novel, fully automated photogrammetric method to generate dense 3d point cloud data. This approach, termed Structure-from-Motion or SfM, requires only limited ground-control and is ideally suited to imagery obtained from low-cost, non-metric cameras acquired either at close-range or using aerial platforms. With numerous survey technologies available, there is a need to determine if simpler and more affordable methods are fit for the purpose of numerical modelling. To address this demand, the hydrodynamic numerical model Delft3D was utilized to simulate various flow conditions of a SfM produced terrain model. Using the SfM software PhotoScan (version 0.9.0) and optical bathymetric mapping, a 0.5 m resolution terrain model was generated for a 1.6 km reach of the braided Ahuriri River, New Zealand. This topography was imported into Delft3D where a 1.5 m and 2.5 m grid resolutions were generated and utilized to simulate a low, medium, and high flow conditions. Following a stringent calibration, hydraulic conditions of velocity, depth, and inundation were tested. Results reveal that average modelled depth errors were comparable to the SfM uncertainty (0.14 m average error), velocity errors of a small anabranch produced average errors of 0.09 m/s, and areal inundation was correctly predicted up to 81% of the observed (inundated and non-inundated areas). Given the river's braid complexity and shallow depths, subtle topographic inaccuracies would greatly influence the model's river routing prediction. Therefore, based on inundation extent results, it can be reasoned that the SfM and optical bathymetric produced terrain model was fit for the purpose of numerical modeling using Delft3D. These results are encouraging, as SfM can be acquired easily and cheaply; thus offering low-budget research the opportunity for long temporal studies. Funding support from the New Zealand Department of Conservation: Project River Recovery

Javernick, L. A.; Caruso, B. S.; Measures, R.; Hicks, M.; Brasington, J.

2013-12-01

355

The contribution of fluvial and mass wasting processes to sedimentary budget in mountain catchments of the southern Apennines, Italy  

NASA Astrophysics Data System (ADS)

Erosion quantification is an important topic for both scientific and social community, although the large number of prediction models developed in the last decades showed controversial results and limited reliability (Boardman, 2006 and references therein). On the other hand, direct measurements of sediment flux are extremely rare and limited to a few years. This is true also for southern Apennines where, in this work, the sediment yield has been estimated in a wide sector of the axial zone, by using simple empirical relationships, such as the statistical correlation between some geomorphic parameters of the drainage network and the measured suspended sediment yield at the outlet of several drainage basins of Italy (Ciccacci et al., 1980). The test area includes several mountain catchments of the central-western sector of the Basilicata region, characterized by strong differences in litho-structural, morphological and tectonic features. In this area, classical and GIS-aided quantitative geomorphic analysis allowed to estimate several geomorphic indexes and topographic attributes, which are used to estimate fluvial turbid transport data (Tu, mean annual suspension sediment yield), an expression of the erosion degree within the drainage basin. In particular, in this study Tu calculation was modified considering also some morphological and climate parameters, with the aim to relate this index to the real physiography of the studied area and to recent (i.e. the last ten years) pluviometric trend. Then, Tu index is converted into a mean denudation rate, giving a mean bulk density to the rocks outcropping into drainage basins. Denudation rates obtained through Tu method have been compared with those estimated by published study of long-term erosion rates and with data of historical sediment accumulation in the artificial reservoir of the Camastra dam. In order to assess also the contribution of mass movement processes to the sedimentary yield, a landslide inventory map has been realized in each studied catchment through systematic aerial photo-interpretation and field survey. Moreover, a comparison between landslide volumes and total sedimentary budget has been carried out in some selected area. The collected dataset represents a basic tool to investigate the morpho-dynamics of the studied catchments and to evaluate sedimentary budget related to both fluvial and hillslope processes. This approach could also be useful to solve practical problems such as burial velocity of an artificial reservoir.

Lazzari, M.; Danese, M.; Gioia, D.

2012-04-01

356

Equatorial Periglacial Terrains, Lacustrine Environments, and Fluvial Networks at the Hesperian-Amazonian Age Boundary on Mars  

NASA Astrophysics Data System (ADS)

The occurrence of a synoptic phase of wet climate conditions on early Mars is well established. Noachian-age (4.1 to 3.7 Ga) terrains are characterized by valley networks, hydrous minerals (clays), integrated lacustrine systems and high erosion rates that indicate relatively extended periods (episodic or continuous) of surface liquid water stability. The disappearance of these geomorphic features and mineralogic signatures in the subsequent epochs (Hesperian, Amazonian) has been classically used to suggest that this wet climate optimum was the only global phase of Earth-like conditions to have occurred on Mars. However, the latest high-resolution orbiter imagery, topography, and spectral data has begun to provide new evidence that local or global changes in the climate allowed for the flow of small volumes of liquid water at the surface of the planet well into the Hesperian (3.7 to 3.4 Ga) and Amazonian (< 3.4 Ga) epochs. Here, we report the latest results of a mapping campaign using Mars Reconnaissance Orbiter Context Camera mosaics (6 m pixel-1) of the equatorial regions of Mars, including the Xanthe Terra and Arabia Terra highland terrains. We identify evidence for a regionally extensive surface hydrologic system that includes small fluvial networks, lacustrine systems (crater lakes), and periglacial terrains (thermokarst). These features are often integrated, forming broad surface hydrologic networks that suggest transitional conditions between stable near-surface ice, standing bodies of water, and fluvial erosion. Impact crater chronology and cross-cutting relationships with nearby catastrophic outflow channels indicate that these features formed at the Hesperian-Amazonian boundary, typically after the catastrophic outflow channels. The water/ice source is not well understood, however, this region of Mars has been previously identified in hydrologic models as an area of groundwater upwelling with the likelihood that this groundwater was nominally frozen in the Hesperian-Amazonian. The regional extent and transitional characteristics of the identified aqueous and periglacial features may indicate an episodic phase of synoptic climate warming on Mars during this period.

Warner, N.; Gupta, S.; Golombek, M. P.; Grindrod, P. M.; Broznak, C.

2012-12-01

357

Mineralogy and morphology of geologic units at Libya Montes, Mars: Ancient aqueously derived outcrops, mafic flows, fluvial features, and impacts  

NASA Astrophysics Data System (ADS)

There is ample evidence of both ancient and long-lasting fluvial activity and chemical alteration in the Libya Montes region south of Isidis Basin. The region hosts Noachian to Amazonian aged surface rocks with extensive outcrops of olivine- and pyroxene-bearing material. Libya Montes also features surface outcrops and/or deposits hosting Fe/Mg-smectite, Fe/Mg-smectite mixed with carbonate and/or other Fe/Mg-rich phyllosilicates, and Al-smectite. These units likely formed through chemical alteration connected with hydrothermal activity resulting from the formation of the Isidis Basin and/or the pervasive fluvial activity throughout this region. The morphology and stratigraphy of the aqueous and mafic minerals are described using High Resolution Imaging Science Experiment and High Resolution Stereo Camera derived digital terrain models. Analyses of the Compact Reconnaissance Imaging Spectrometer for Mars spectra show variations in the chemistry of the Fe/Mg-smectite from nontronite-like exposures with spectral features near 2.29 and 2.4 m more consistent with Fe3+2OH groups in the mineral structure, and saponite-like outcrops with spectral features near 2.31 and 2.38 m characteristic of Mg2+3OH groups. These Fe/Mg-smectite bearing materials also have bands near 1.9 m due to H2O and near 2.5 m that could be due to the smectite, other phyllosilicates, and carbonates. All regions exhibiting carbonate features near 3.4-3.5 m also have features consistent with the presence of olivine and Fe/Mg-smectite, indicating that the carbonate signatures occur in rocks likely containing a mixture of these minerals. The Al-smectite-bearing rocks have bands near 1.41, 1.91, and 2.19 m that are more consistent with beidellite than other Al-phyllosilicates, indicating a higher-temperature or diagenetically processed origin for this material. Our interpretation of the geologic history of this region is that ancient Noachian basaltic crustal materials experienced extensive aqueous alteration at the time of the Isidis impact, during which the montes were also formed, followed by emplacement of a rough olivine-rich lava or melt, and finally the smooth pyroxene-bearing caprock unit.

Bishop, Janice L.; Tirsch, Daniela; Tornabene, Livio L.; Jaumann, Ralf; McEwen, Alfred S.; McGuire, Patrick C.; Ody, Anouck; Poulet, Francois; Clark, Roger N.; Parente, Mario; McKeown, Nancy K.; Mustard, John F.; Murchie, Scott L.; Voigt, Joana; Aydin, Zeynep; Bamberg, Marlene; Petau, Andreas; Michael, Gregory; Seelos, Frank P.; Hash, Christopher D.; Swayze, Gregg A.; Neukum, Gerhard

2013-03-01

358

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

359

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)

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 (1903'N/2031'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 (Krpelin 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.

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

2014-05-01

360

Reconstructing Holocene bottom water oxygenation and fluvial discharge in the marine environment near Eureka, California using a portable XRF method  

NASA Astrophysics Data System (ADS)

X-ray fluorescence (XRF) spectrometry is a method of performing chemical composition analysis of bulk samples. Traditionally, samples are processed gradually over days or weeks to create topographically flat, dry, and homogenous compositions. The current experiment applies this technique for rapid measurement of chemical composition in intact marine sediment cores. We used a handheld Thermo Scientific NitonXL3t-950 XRF to measure the core TN062-O550 (40.867 N, 124.572 W, 550 m water depth), which was collected from 13 km off the coast of Eureka, California. Custom calibrations were developed to accommodate marine sediments, and measurements collected by hand were compared to those taken using a custom-built sediment core stand. Following the initial calibration tests, the portable XRF was used to assess water column oxygen levels within TN062-O550 over the last 4000 years. This assessment was based upon the relatively well-known correspondence between iron and titanium, which can be used to infer the relative abundance of ferric and ferrous minerals, and therefore serve as a proxy for ambient oxygen levels. In addition to testing the oxygenation, these analyses were used to investigate the potential correlation between iron levels and deposition by fluvial discharge and/or surface run-off (rainfall). We found a strongly positive correlation between iron and titanium throughout the length of the core. This correlation suggests that more oxidized iron has accumulated than reduced iron, thus implying oxygenation in the water column and/or upper sediment profile. This is further supported by pervasive bioturbation in the sediment core. These results also have implications for applying these geochemical data as a proxy for regional precipitation and/or fluvial deposition in the marine environment. Based on a preliminary age-depth model developed for TN062-O550, and application of the iron and titanium concentrations as a precipitation proxy, there is a relative maximum within the last ~200 years, as well as a period of high variability between approximately 2500 and 1500 calibrated years before present (cal yr bp). These results demonstrate the potential for the portable XRF for relatively rapid chemical measurement and data collection from marine sediments. However, use of the portable XRF still requires validation of the data it acquires, particularly when applied to wet sediments. To address this issue, analyses are underway to identify the distinctions between wet and dry chemical compositions from TN062-O550. Nevertheless, portable XRF spectrometry does provide a fast, non-destructive, and inexpensive method of collecting accurate chemical data that few instruments can offer.

Burtt, D. G.; Addison, J. A.; Foster, A. L.

2013-12-01

361

Remnants of Miocene fluvial sediments in the Negev Desert, Israel, and the Jordanian Plateau: Evidence for an extensive subsiding basin in the northwestern margins of the Arabian plate  

NASA Astrophysics Data System (ADS)

Relics of a thick, widely spread, fluvial sequence of Early Miocene age are scattered throughout southern Israel, eastern Sinai, the Dead Sea Rift Valley and the western margins of the Jordanian Plateau. These relics are mainly preserved in structural lows, karstic systems, and abandoned stream valleys. The paleogeography of this fluvial system was reconstructed based on the relations between the sequence remnants and the main structural and morphological features of the southeastern Levant region. Three sedimentary associations were identified in the Miocene sequence: a lower part dominated by locally derived clastic sediments; a thicker middle part, composed mostly of far-field allochthonous clastic sediments; and an upper part composed of local as well as allochthonous sediments. The two lower parts are regionally distributed whereas the upper part is syn-tectonic and confined to the Dead Sea basin and the Karkom graben in the central Negev. The composition of the far-field allochthonous sediments points to a provenance of Precambrian crystalline rocks of the Arabo-Nubian massif that were exposed along the uplifted shoulders of the Red Sea Rift as the upper drainage basin of the fluvial system. The diverse mammal remains found in this fluvial sequence suggest a complex of savanna, forests and fluvial habitats similar to those of present East Africa, with monsoon-type rains, which were the dominant water source of the rivers. The thickness of the Miocene sequence in the central Negev is at least 1700 m, similar to that of the subsurface sequence encountered in the Dead Sea basin. This similarity suggests that both were parts of an extensive subsiding sedimentary basin that developed between the Neo-Tethys and the uplifted margins of the Red Sea. The relations between the reconstructed pre-depositional landscape of southern Israel during the Early Miocene and the overlying fluvial sequence indicate that the entire area was buried under several hundred meters of fluvial sediments, reflecting a subsidence of the northern margins of the African continent (Arabian plate) before its breakup and the splitting of the Sinai-Israel subplate by the Dead Sea Transform. During the early Middle Miocene the subsidence was inversed as the mountainous backbone of Israel was uplifted. The uplift triggered a large scale denudation that removed the thick Early Miocene fluvial sequence from the Negev and transported the eroded sediments northwestward toward the eastern Mediterranean basin. Additional uplift during the late-Middle Miocene was associated with entrenchment of the Be'er Sheva Valley between the Judea Mountains in the north and the Negev Highlands in the south. This valley was flooded by the sea during the Late Miocene. We suggest that the formation of the Early Miocene subsiding basin at the northern edge of the Arabian sub-plate predated the breakup of the Arabian plate by the DST. The inversion of the subsiding regime, which led to the establishment of the Negev Highlands seems to be intimately related to the detachment of the Sinai-Israel sub-plate from the Arabian plate during the Middle Miocene.

Zilberman, Ezra; Calvo, Ran

2013-06-01

362

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

Microsoft Academic Search

The Oklahoma Geological Survey (OGS), the Geological Information Systems department, and the School of Petroleum and Geological Engineering at the University of Oklahoma have engaged 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

C. J. Mankin; M. K. Grasmick

1993-01-01

363

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

Microsoft Academic Search

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

C. J. Mankin; M. K. Banken

1995-01-01

364

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

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

C. J. Mankin; M. K. Banken

1995-01-01

365

Identification and evaluation of fluvial-dominated deltaic (Class I oil) reservoirs in Oklahoma. Quarterly technical progress report, July 1September 30, 1995  

Microsoft Academic Search

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 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

C. J. Mankin; M. K. Banken

1995-01-01

366

Identification and evaluation of fluvial-dominated deltaic (Class I Oil). Quarterly technical progress report, April 1, 1995June 30, 1995  

Microsoft Academic Search

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 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

C. J. Mankin; M. K. Banken

1995-01-01

367

Identification and evaluation of fluvial-dominated deltaic (Class I oil) reservoirs in Oklahoma. Quarterly technical progress report, April 1, 1993June 30, 1993  

Microsoft Academic Search

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

G. J. Mankin; M. K. Banken

1993-01-01

368

Identification and evaluation of fluvial-dominated deltaic (class 1 oil) reservoirs in Oklahoma. Quarterly technical progress report, July 1, 1993September 30, 1993  

Microsoft Academic Search

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

C. J. Mankin; M. K. Banken

1994-01-01

369

Human and climatic impact on the environment as derived from colluvial,fluvial and lacustrine archivesexamples from the Bronze Age to the Migration period,Germany  

Microsoft Academic Search

Investigation of colluvial,fluvial and lacustrine sediment archives from 12 sites in Germany for the last ca 5000 years demonstrates that there is no synchronous development of the cultural landscape. This can only be explained,if climate is not the dominating control mechanism. However,to a certain degree there is a climatic influence,like during the slight climatic deteriorations immediately following the Holocene climatic

Bernd Zolitschkaa; Karl-Ernst Behre

2003-01-01

370

The significance of incision and fluvial sedimentation in the Basal White River Group (Eocene-Oligocene), Badlands of South Dakota, U.S.A.  

NASA Astrophysics Data System (ADS)

A newly defined lithostratigraphic unit, the Chamberlain Pass Formation (CPF), records the initial episode of incision, fluvial sedimentation, and pedogenesis in SW South Dakota following the retreat of the Cretaceous Interior Seaway. The CPF is Middle(?) to Late Eocene in age, and consists of fluvial sandstone and mudstone. Pedogenic modification of the unit has created a distinctive pedostratigraphic unit, the Interior Paleosol Series. The CPF thickens from west to east, achieving a maximum channel-belt thickness of ? 11 m. Paleoflow data indicate that deposition of the CPF was restricted to a fault-controlled basin southeast of the Black Hills uplift. Sandstones in the CPF were derived from a recycled sedimentary rock source area to the west. In contrast, sandstones in the overlying Chadron Formation (Late Eocene) had a variety of sources including the Precambrian core rocks of the Black Hills uplift. Deposition of the CPF brackets four significant Paleogene changes in baselevel that occurred in this region. These events were: (1) Late Cretaceous to Middle(?) Eocene relative baselevel fall, weathering and erosion of the Cretaceous Pierre Shale to form the Yellow Mounds Paleosol, and fluvial incision; (2) Middle(?) to Late Eocene relative baselevel rise and deposition of the CPF; (3) Late Eocene relative baselevel fall, weathering and erosion of the CPF to form the Interior Paleosol, and fluvial incision; and (4) Late Eocene to Oligocene relative baselevel rise and deposition of the Chadron Formation. The first event was probably eustatic, the second was controlled primarily by local subsidence in a fault-bounded basin, the third records the tectonic uplift and unroofing of the Black Hills, and the fourth event was probably primarily controlled by eustasy, but other factors may have been important.

Evans aui]Dennis O.^Terry, James E.

1994-04-01

371

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

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

M. K. Banken; R. Andrews

1997-01-01

372

Object-based classification of vegetation and terrain topography in Southwestern Amazonia (Brazil) as a tool for detecting ancient fluvial geomorphic features  

NASA Astrophysics Data System (ADS)

Reconstructing the evolution of large tropical fluvial systems over the geological time is challenging, particularly in areas such as the Amazonian lowlands where basic geological and geomorphological data are still scarce relatively to the large dimension of the region. In such areas, remote sensing data are useful for detecting ancient morphological features that may reveal past fluvial dynamics. In this study, we explored object-based image analysis (OBIA) in the Madeira-Purus interfluve, Southwestern Brazilian Amazonia, integrating geospatial data including Landsat satellite multispectral images, the digital elevation model (DEM) acquired during the Shuttle Radar Topography Mission (SRTM), and stream channels digitized from topographic maps. This approach provided the basis to categorize automatically classes with contrasting vegetation and/or topographic characteristics within the dense tropical forest over an extensive and relatively flat forested area. The main goal was to use these classes as a surrogate for the recognition of ancient geomorphic features consisting mainly of paleochannels that may help reconstructing fluvial history in space and time. Landsat optical images with stream vector were appropriate to classify open vegetation areas that grow over paleochannels, but failed to identify these objects when they were located over forested areas. However, the digital elevation model (DEM) derived from the Shuttle Radar Topography Mission (SRTM) was successful to detect these objects even in forested areas. Topographic survey undertaken in the field increased the classification reliability by demonstrating true terrain variations along transects measured across the paleochannels. Based on this technique, networks of dendritic paleochannels were mapped and related to ancient tributaries of the Madeira River that had their courses flowing opposite to main modern streams. This denotes a significant change in fluvial dynamics over time, most likely resulting from tectonic tilting.

Bertani, Thiago de Castilho; Rossetti, Dilce de Ftima; Albuquerque, Paulo Cesar Gurgel

2013-10-01