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Sample records for proglacial fluvial sedimentation

  1. Streamflow response to glacier melt and related fluvial sediment transport in a proglacial Alpine river system

    Science.gov (United States)

    Morche, D.; Schuchardt, A.; Baewert, H.; Weber, M.; Faust, M.

    2016-12-01

    Glaciers in the European Alps are retreating since the end of the Little Ice Age around 1850. Where the glaciers shrink, they leave unconsolidated sediment stores (moraines, till, glacifluvial deposits). These sediment stores are highly vulnerable for being subsequently eroded and are thus a key variable (source) in the fluvial sediment budget of proglacial areas. The fluvial system in proglacial areas is more or less continuously fed with (fine) sediment by glacial melt water (glacial milk) during the ablation period and infrequently (e.g. during rainstorm events) supplied with sediment by landslides, debris flows, rock fall or fluvial transport from the slopes. A part of the sediment input is temporary stored in intermitted sinks, such as the river bed, bars or braid plains. These storages can be reworked and then become sources for fluvial sediment transport mainly during floods. These sediment transporting processes are highly variable in both, the temporal and spatial scale. A research project has been set up in the Kaunertal valley, Austrian Alps. The presented part of this joint project is focussed on the quantification of recent fluvial sediment dynamics in the proglacial Fagge River below the glacier Gepatschferner. The glacier is located in the Eastern European Alps at the south end of the Kaunertal valley covering an area of 15.7 km² (2012) and is drained by the Fagge River. During the years 2012 to 2015 the Gepatschferner has shown an accelerated glacial retreat leading to the exposure of unconsolidated sediments as well as bedrock areas. The main aim of the presented part of the joint project is the investigation of the fluvial sediment transport rates in the proglacial Fagge River in the Kaunertal valley. Sediment output of the glacial meltwater stream was measured during the ablation periods at a gauging station installed in front of the glacier outlet. Water level was recorded every 15 minutes and discharge measurements were made at different

  2. Particle Size Characteristics of Fluvial Suspended Sediment in Proglacial Streams, King George Island, South Shetland Island

    Science.gov (United States)

    Szymczak, Ewa

    2017-12-01

    In this study, the characterization of particle size distribution of suspended sediment that is transported by streams (Ornithologist Creek, Ecology Glacier Creeks, Petrified Forest Creek, Czech Creek, Vanishing Creek, Italian Creek) in the area of the Arctowski Polish Antarctic Station is presented. During the first period of the summer season, the aforementioned streams are supplied by the melting snow fields, while later on, by thawing permafrost. The water samples were collected from the streams at monthly intervals during the Antarctic summer season (January - March) of 2016. The particle size distribution was measured in the laboratory with a LISST-25X laser diffraction particle size analyser. According to Sequoia Scientific Inc., LISST-25X can measure particle sizes (Sauter Mean Diameter) between 2.50 and 500 μm. The results of particle size measurements were analysed in relation to flow velocity (0.18–0.89 m/s), the cross-sectional parameters of the streams, suspended sediment concentration (0.06–167.22 mg/dm3) and the content of particulate organic matter (9.8–84.85%). Overall, the mean particle size ranged from 28.8 to 136 μm. The grain size of well-sorted sediments ranged from 0.076 to 0.57, with the skewness and kurtosis values varying from -0.1 to 0.4, and from 0.67 to 1.3, respectively. Based on the particle size characteristics of suspended sediment, the streams were divided into two groups. For most of the streams, the sediment was very well sorted, while fine sand and very fine sand were dominant fractions displaying symmetric and platykurtic distributions, respectively. Only in two streams, the suspended sediment consisted of silt-size grains, well or moderately well sorted, with coarse-skewness and mostly mesokurtic distribution. The C-M chart suggested that the transportation processes of suspended sediment included the suspended mode only. The grain-size distribution of suspended sediment was mainly influenced by the stream runoff

  3. Sedimentation in arctic proglacial lakes: Mittivakkat Glacier, SE Greenland

    DEFF Research Database (Denmark)

    Hasholt, Bent; Walling, Desmond Eric; Owens, P.N.

    2000-01-01

    lake sedimentation, sediment yields, sediment sources, calcium-137, lead-210, archz, proglacial, Greenland......lake sedimentation, sediment yields, sediment sources, calcium-137, lead-210, archz, proglacial, Greenland...

  4. Glacier retreat and associated sediment dynamics in proglacial areas: a case study from the Silvretta Alps, Austria

    Science.gov (United States)

    Felbauer, Lucia; Pöppl, Ronald

    2016-04-01

    Global warming results in an ongoing retreat of glaciers in the Alps, leaving behind large amounts of easily erodible sediments. In addition, the debuttressing of rock-walls and the decay of permafrost in the high mountain regions facilitates mass movements of potential disastrous consequences, such as rock falls, landslides and debris flows. Therefore, it is highly important to quantify the amount of sediments that are supplied from the different compartments and to investigate how glacial retreat influences sediment dynamics in proglacial areas. In the presented work glacier retreat and associated sediment dynamics were investigated in the Kromer valley (Silvretta Alps, Austria) by analyzing remote sensing data. Glacial retreat from the period of 1950 to 2012 was documented by interpreting aerial photographs. By digitizing the different stages of the glaciers for six time frames, changes in glacier area and length were mapped and quantified. In order to identify, characterize and quantify sediment dynamics in the proglacial areas a high resolution DEM of difference (DoD) between 2007 and 2012 was created and analyzed, further differentiating between different zones (e.g. valley bottom, hillslope) and types of geomorphic processes (e.g. fluvial, gravitational). First results will be presented at the EGU General Assembly 2016.

  5. The contribution of bank and surface sediments to fluvial sediment ...

    African Journals Online (AJOL)

    Sediment source studies involving a simple mixing model was undertaken in the Pra River Basin in Ghana using a single tracer 210Pb to determine the relative contribution of surface and bank sediments to the fluvial sediment transport. Sediment source tracing was performed on the basis of sub-basins by comparing the ...

  6. Channel morphodynamics on a small proglacial braid plain (Fagge River, Gepatschferner, Austria

    Directory of Open Access Journals (Sweden)

    D. Morche

    2015-03-01

    Full Text Available Braid plains are important sediment stores in high mountains, particularly in the glacier forefields of Alpine glaciers. Proglacial braid plains receive sediment input from glacial meltwater and proglacial sediment sources like moraines and glacio-fluvial deposits. The channel morphodynamics on the braid plains are strongly related to the sediment transport and flow regime of the proglacial river. This study deals with channel morphodynamics on a small proglacial braid plain in the European Alps. It focuses on two different time scales. Decadal channel planform changes were assessed by remote sensing approaches. The recent channel bed changes were investigated by cross-sectional surveys and particle counts in 2013. This study is part of the DFG/FWF funded interdisciplinary research project PROSA (High-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps.

  7. Proglacial lake sediments – a basis for uninterrupted chronicles of the Holocene glacier variations

    Directory of Open Access Journals (Sweden)

    M. Y. Alexandrin

    2015-01-01

    Full Text Available The article covers the origin of paleolimnological method in glaciology, concerns the theoretical background of the approach, and focuses on the principal methods of analysis of the lake sediments and creating the sedimentary age-depth models. Lake sediments can provide a basis for creating uninterrupted reconstructions of the Holocene glacier variations with high resolution. The fundament of paleolimnological method is based on the differences between glacial and non-glacial components of the bottom sediments of proglacial lakes. The glacial signal in the lake sediments was originally distinguished by measuring the organic content of the sediment (normally with loss-on-ignition and the magnetic properties of the sediment. Subsequent methods of analysis could yield more precision and normally include geochemical composition (with the use of high-resolution scanning x-ray fluorescence analysis, use of biogenic indicators (such as pollen and diatoms contained in the sediment and more. Obtaining the most accurate age of the sediment is a crucial question in subsequent application of the sediment parameters for reconstruction of glacier variability. The article covers various methods of dating the lake sediment – radiocarbon, Cs- and Pb-isotope dating, varve counting. Techniques of creating age-depth models are taken into account. A state-of-the-art application of sedimentary properties in paleoglaciology yields a reconstruction of a former equilibrium line altitude – ELA. The article focuses on the basis of the ELA reconstruction approach. Successful examples of reconstructions of glacier variations based on the lake sediments can be found throughout the majority of the glaciated regions of the planet. The article states the most prominent of them and gives an update on the current progress in paleolimnological research in the Caucasus Mountains.

  8. Fluvial processes on Mars: Erosion and sedimentation

    Science.gov (United States)

    Squyres, Steven W.

    1988-01-01

    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.

  9. Fluvial sediment transport in a glacier-fed high-mountain river (Riffler Bach, Austrian Alps)

    Science.gov (United States)

    Morche, David; Weber, Martin; Faust, Matthias; Schuchardt, Anne; Baewert, Henning

    2017-04-01

    High-alpine environments are strongly affected by glacier retreat since the Little Ice Age (LIA). Due to ongoing climate change the hydrology of proglacial rivers is also influenced. It is expected that the growing proportions of snow melt and rainfall events will change runoff characteristics of proglacial rivers. Additionally, the importance of paraglacial sediment sources in recently deglaciating glacier forefields is increasing, while the role of glacial erosion is declining. Thus complex environmental conditions leading to a complex pattern of fluvial sediment transport in partly glaciated catchments of the European Alps. Under the umbrella of the joint PROSA-project the fluvial sediment transport of the river Riffler Bach (Kaunertal, Tyrol, Austria) was studied in 3 consecutive ablation seasons in order to quantify sediment yields. In June 2012 a probe for water level and an automatic water sampler (AWS) were installed at the outlet of the catchment (20km2). In order to calculate annual stage-discharge-relations by the rating-curve approach, discharge (Q) was repeatedly measured with current meters and by salt dilution. Concurrent to the discharge measurements bed load was collected using a portable Helley-Smith sampler. Bed load samples were weighted and sieved in the laboratory to gain annual bed load rating curves and grain size distributions. In total 564 (2012: 154, 2013: 209, 2014: 201) water samples were collected and subsequently filtered to quantify suspended sediment concentrations (SSC). Q-SSC-relations were calculated for single flood events due to the high variability of suspended sediment transport. The results show a high inter- and intra-annual variability of solid fluvial sediment transport, which can be explained by the characteristics of suspended sediment transport. Only 13 of 22 event-based Q-SSC-relations show causal dependency. In 2012, during a period with multiple pluvial-induced peak discharges most sediment was transported. On the

  10. Variability of solid load in the proglacial Fagge River, Tyrol (Austria)

    Science.gov (United States)

    Baewert, Henning; Weber, Martin; Faust, Matthias; Morche, David

    2016-04-01

    Glaciers can strongly affect sediment dynamics in high-mountain basins. They receive clastic material from rock walls by gravitational processes of various magnitudes (rock slides to rockfalls) or by subglacial erosion and transport sediments downvalley like a conveyor belt. At the glacier tongue the meltwater with its accompanying river load enters the proglacial system. Fine material is moving in suspension leading to turbid meltwater. The coarse fraction of the meltwater load is rolling or sliding as bedload on the proglacial channel bed. As glaciers are vulnerable to and thus indicators of climate change the sediment transfer systems in Alpine glacier basins will respond as well. Since the end of the Little Ice Age (LIA) around 1850 glacier in the European Alps have been melting down and their front lines have been retreating. Where the glacier ice is gone large amounts unconsolidated sediments are deposited (moraines, glaciofluvial deposits) and can easily be reworked during subsequent rain storms or snowmelt. As a consequence it is of great concern whether more solid load (higher sediment availability) or less solid load (trapping effect of proglacial lakes) is transported in proglacial rivers in the near future. Due to glacier retreat the amount of unconsolidated, sparsely vegetated sediments, which are prone to rapid remobilization, is increasing. Because more of these sediments are available for fluvial sediment transport, it is generally assumed that glacier retreat leads to an increase in sediment discharge from proglacial zones. The main objective of this study is to present a budget of the fluvial sediment transport within the proglacial Fagge River for the observation period 2012 - 2014. This quantification of solid sediment transport is needed for further investigations on the way to a holistic sediment budget for the whole glaciated catchment of the Gepatschferner in Tyrol/Austria.

  11. Fluvial sediment fingerprinting: literature review and annotated bibliography

    Science.gov (United States)

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

    2014-01-01

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

  12. A manual to identify sources of fluvial sediment

    Science.gov (United States)

    Gellis, Allen C.; Fitzpatrick, Faith A.; Schubauer-Berigan, Joseph

    2016-01-01

    sediment sources early in the design of the sediment budget will help later in deciding which tools are necessary to monitor erosion and/or deposition at these sources. Tools can range from rapid inventories to estimate the sediment budget or quantifying sediment erosion, deposition, and export through more rigorous field monitoring. In either approach, data are gathered and erosion and deposition calculations are determined and compared to the sediment export with a description of the error uncertainty. Findings are presented to local stakeholders and management officials.Sediment fingerprinting is a technique that apportions the sources of fine-grained sediment in a watershed using tracers or fingerprints. Due to different geologic and anthropogenic histories, the chemical and physical properties of sediment in a watershed may vary and often represent a unique signature (or fingerprint) for each source within the watershed. Fluvial sediment samples (the target sediment) are also collected and exhibit a composite of the source properties that can be apportioned through various statistical techniques. Using an unmixing-model and error analysis, the final apportioned sediment is determined.

  13. Magnitude and frequency in proglacial rivers: a geomorphological and sedimentological perspective

    Science.gov (United States)

    Marren, Philip M.

    2005-05-01

    Proglacial fluvial sedimentary systems receive water from a variety of sources and have variable discharges with a range of magnitudes and frequencies. Little attention has been paid to how these various magnitude and frequency regimes interact to produce a distinctive sedimentary record in modern and ancient proglacial environments. This paper reviews the concept of magnitude and frequency in relation to proglacial fluvial systems from a geomorphic and sedimentary perspective rather than a hydrological or statistical perspective. The nature of the meltwater inputs can be characterised as low-magnitude-high-frequency, primarily controlled by ablation inputs from the source glacier, or high-magnitude-low-frequency, primarily controlled by 'exceptional' inputs. The most important high-magnitude-low-frequency inputs are catastrophic outburst floods, often referred to by the term jökulhlaup (Icelandic for glacier-burst). Glacier surges are an additional form of cyclical variation impacting the proglacial environment, which briefly alter the volumes and patterns of meltwater input. The sedimentary consequences of low-magnitude-high-frequency discharges are related to frequent variations in stage, the greater directional variability that sediment will record, and the increased significance of channel confluence sedimentation. In contrast, the most significant characteristics of high-magnitude-low-frequency flooding include the presence of large flood bars and mid-channel 'jökulhlaup' bars, hyperconcentrated flows, large gravel dunes, and the formation of ice-block kettle hole structures and rip-up clasts. Glacier surges result in a redistribution of low-magnitude-high-frequency processes and products across the glacier margin, and small floods may occur at the surge termination. Criteria for distinguishing magnitude and frequency regimes in the proglacial environment are identified based on these major characteristics. Studies of Quaternary proglacial fluvial sediments

  14. Groundwater hydrochemistry in the active layer of the proglacial zone, Finsterwalderbreen, Svalbard

    Science.gov (United States)

    Cooper, R.J.; Wadham, J.L.; Tranter, M.; Hodgkins, R.; Peters, N.E.

    2002-01-01

    Glacial bulk meltwaters and active-layer groundwaters were sampled from the proglacial zone of Finsterwalderbreen during a single melt season in 1999, in order to determine the geochemical processes that maintain high chemical weathering rates in the proglacial zone of this glacier. Results demonstrate that the principle means of solute acquisition is the weathering of highly reactive moraine and fluvial active-layer sediments by supra-permafrost groundwaters. Active-layer groundwater derives from the thaw of the proglacial snowpack, buried ice and glacial bulk meltwaters. Groundwater evolves by sulphide oxidation and carbonate dissolution. Evaporation- and freeze-concentration of groundwater in summer and winter, respectively produce Mg-Ca-sulphate salts on the proglacial surface. Re-dissolution of these salts in early summer produces groundwaters that are supersaturated with respect to calcite. There is a pronounced spatial pattern to the geochemical evolution of groundwater. Close to the main proglacial channel, active layer sediments are flushed diurnally by bulk meltwaters. Here, Mg-Ca-sulphate deposits become exhausted in the early season and geochemical evolution proceeds by a combination of sulphide oxidation and carbonate dissolution. At greater distances from the channel, the dissolution of Mg-Ca-sulphate salts is a major influence and dilution by the bulk meltwaters is relatively minor. The influence of sulphate salt dissolution decreases during the sampling season, as these salts are exhausted and waters become increasingly routed by subsurface flowpaths. ?? 2002 Elsevier Science B.V. All rights reserved.

  15. Holocene glacier activity on Kerguelen Island: preliminary results from a novel proglacial lake sediment record

    Science.gov (United States)

    Støren, Eivind; Bakke, Jostein; Arnaud, Fabien; Poulenard, Jérôme; Fanget, Bernard; Malet, Emmanuel; Sabatier, Pierre

    2016-04-01

    The Polar-regions are changing rapidly as greenhouse warming is continuing with huge impact on e.g. sea ice extent and snow cover. This change triggers teleconnections to low latitude areas challenging societies and human activity. We have, however, very little quantitative information of past climate in the Polar-regions that can be used to evaluate the potential responses and the response patterns to forcing changes and changes in boundary conditions. Whatever anthropogenic changes may occur in the future, they will be superimposed on, and interact with, natural climate variations due to all the forcing we are aware of. This means we need to better document past climate/environmental variability of the Polar-regions. Especially in the Southern Ocean there are few time series recording past climate due to few suitable land areas and the few Sub-Antarctic Islands is remote and has cumbersome logistics. Continuous terrestrial records from this region are therefore urgently needed for constraining future scenarios from earth system models. Glaciers and ice caps are still ubiquitous in the Polar-regions, although they are rapidly shrinking due to the on-going warming. The continuous sedimentary records produced by glaciers, which are stored in downstream lakes, represent supreme archives of past variability wherefrom quantitative information of key climate system components can be extracted. Kerguelen Island is located within the Antarctic Circumpolar Current and the Southern Westerly wind belt and contains several glaciers and smaller ice caps. Terrestrial archives recording past history of the glaciers at Kerguelen thus have a unique potential to record past changes in oceanic and atmospheric circulation patterns from southern mid-latitudes. Here we present preliminary results from the first distal glacier-fed lake that is sampled from Kerguelen Island. A 2.8 m long sediment core was obtained from Lac Guynemer (121masl.) located at the Peninsule Loranchet at the

  16. Modeling plan-form deltaic response to changes in fluvial sediment supply

    NARCIS (Netherlands)

    Nienhuis, J.H.; Ashton, A.D.; Roos, Pieter C.; Hulscher, Suzanne J.M.H.; Giosan, L.; Kranenburg, W.M.; Horstman, E.M.; Wijnberg, K.M.

    2012-01-01

    This study focuses on the effects of changes in fluvial sediment supply on the plan-form shape of wave-dominated deltas. We apply a one-line numerical shoreline model to calculate shoreline evolution after (I) elimination and (II) time-periodic variation of fluvial input. Model results suggest four

  17. Characteristics and historical development of fluvial sediments in the UAE

    Science.gov (United States)

    El Saiy, A.

    2012-04-01

    Fluvial deposits in the United Arab Emirates include a wide range of different lithologies and textures ranging from wadi and alluvial fan gravels, sands, silts and clay of different morphology, structures and cementation degree. These deposits represent vital economic, cultural and environmental resources in the UAE. In addition to their direct utilization in the industry as construction materials, agricultural ground and more, they are significant groundwater reservoirs (aquifers) and provide space for landfills and waste disposal. Here we present, field data coupled with geomorphologic observations and Be-10 and C-14 analyses of alluvium wadi deposits and related terraces located in the north and north-eastern parts of the UAE. The study area is strongly affected by the obduction of Oman ophiolite and subsequent tectonic activities during the late Cenozoic times. Deep incised valleys cut through the mountain ranges and deposit a mixture of gravel to clayey sediments that commonly reach a thickness of up to 30 m, but thicker sections were also encountered in scattered places. Alluvial-related terraces are developed inland and along the sea shore where deposition seems to have been interrupted by either riverine or marine peneplaination. In addition to carbonate and ophiolite dominated lithologies in the alluviums, some clay minerals and cementation by gypsum and anhydrites is found. Results of Be-10 and C-14 measurements of the clay-silt matrix and selected carbonates will be presented in relation to dating and paleoclimatic events.

  18. Analysis of Fluvial Sediment Discharges into Kubanni Reservoir ...

    African Journals Online (AJOL)

    The sediment discharges into the Kubanni Reservoir (KR) has been measured and analysed in this study. The predominant sandy-clay sediment in the reservoir has an estimated total sediment load of 20,387,000 kg/year. The depth and area coverage of the reservoir was surveyed using a defined distributed grid line ...

  19. Branched GDGT signals in fluvial sediments of the Danube River basin : Method comparison and longitudinal evolution

    NARCIS (Netherlands)

    Freymond, Chantal V.; Peterse, Francien; Fischer, Lorena V.; Filip, Florin; Giosan, Liviu; Eglinton, Timothy I.

    Abundances and distributional changes of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in fluvially influenced sediments are used in various paleoclimate studies to reconstruct variations in soil export, continental air temperature and soil pH in corresponding river basins. For accurate

  20. The legacy of lead (Pb) in fluvial bed sediments of an urban drainage basin, Oahu, Hawaii.

    Science.gov (United States)

    Hotton, Veronica K; Sutherland, Ross A

    2016-03-01

    The study of fluvial bed sediments is essential for deciphering the impact of anthropogenic activities on water quality and drainage basin integrity. In this study, a systematic sampling design was employed to characterize the spatial variation of lead (Pb) concentrations in bed sediment of urban streams in the Palolo drainage basin, southeastern Oahu, Hawaii. Potentially bioavailable Pb was assessed with a dilute 0.5 N HCl extraction of the  Pukele (19) > Waiomao (8). Comparisons to sediment quality guidelines and potential toxicity estimates using a logistic regression model (LRM) indicated a significant potential risk of Palolo Stream bed sediments to bottom-dwelling organisms.

  1. Sediment budgets as an organizing framework in fluvial geomorphology

    Science.gov (United States)

    Leslie Reid; Thomas Dunne

    2016-01-01

    Sediment budgets describe the input, transport, storage, and export of sediment in a geomorphic system. Such budgets can be used to address questions regarding how changes in catchment conditions affect channels, how long the effects will last, and what the sequence of responses will be. This chapter defines and describes budget components, outlines strategies...

  2. 6. The Contribution of Bank and Surface Sediments to Fluvial ...

    African Journals Online (AJOL)

    user

    2005-03-17

    Mar 17, 2005 ... sustainability of reservoirs/dams for hydro-power generation, potable water supply, and irrigation (e.g. .... Such information is required to design effective sediment and non-point pollution control strategies. ...... Universal Soil Loss Equation (RUSLE). Ghana J. Geogr. 7(2): 38–57. Matisoff G. and Whiting P. J. ...

  3. Analysis of Fluvial Sediment Discharges into Kubanni Reservoir ...

    African Journals Online (AJOL)

    User

    conventional methods used to measure suspended sediment concentration in a river are sampling by point or depth integration in the verticals of the selected river and/or in- situ measurements using apparatus such as nuclear gauges, photoelectric turbidity meter and vibration device, Xlaoqing [4]. Figure 2 Map of Kubanni ...

  4. Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity

    Science.gov (United States)

    Darby, Stephen E.; Hackney, Christopher R.; Leyland, Julian; Kummu, Matti; Lauri, Hannu; Parsons, Daniel R.; Best, James L.; Nicholas, Andrew P.; Aalto, Rolf

    2016-11-01

    The world’s rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a considerable fraction being sequestered in large deltas, home to over 500 million people. Most (more than 70 per cent) large deltas are under threat from a combination of rising sea levels, ground surface subsidence and anthropogenic sediment trapping, and a sustainable supply of fluvial sediment is therefore critical to prevent deltas being ‘drowned’ by rising relative sea levels. Here we combine suspended sediment load data from the Mekong River with hydrological model simulations to isolate the role of tropical cyclones in transmitting suspended sediment to one of the world’s great deltas. We demonstrate that spatial variations in the Mekong’s suspended sediment load are correlated (r = 0.765, P < 0.1) with observed variations in tropical-cyclone climatology, and that a substantial portion (32 per cent) of the suspended sediment load reaching the delta is delivered by runoff generated by rainfall associated with tropical cyclones. Furthermore, we estimate that the suspended load to the delta has declined by 52.6 ± 10.2 megatonnes over recent years (1981-2005), of which 33.0 ± 7.1 megatonnes is due to a shift in tropical-cyclone climatology. Consequently, tropical cyclones have a key role in controlling the magnitude of, and variability in, transmission of suspended sediment to the coast. It is likely that anthropogenic sediment trapping in upstream reservoirs is a dominant factor in explaining past, and anticipating future, declines in suspended sediment loads reaching the world’s major deltas. However, our study shows that changes in tropical-cyclone climatology affect trends in fluvial suspended sediment loads and thus are also key to fully assessing the risk posed to vulnerable coastal systems.

  5. An ancient example of fluvial cave sediment derived from dust (eolian silt) infiltration

    Science.gov (United States)

    Evans, J. E.

    2011-12-01

    Silt-rich grain size distributions are geologically rare and typically eolian. Such sediments (and lithified equivalents) are called dust/dustites in a general case, or loess/loessite in the special case of eolian silts derived from glacial deposits. In both cases, silt-rich deposits require a source area of silt-sized materials, transport mechanisms (prevailing winds of sufficient energy) and one or more depositional mechanisms (such as trapping in the lee of topographic obstacles or adhesion to surfaces with moisture or vegetation). This study evaluates a third type of silt-rich geological deposit, paleo-cave sediments derived from mixtures of dust (eolian silt) and karst breccias. Cave sediments can be autochthonous (speleothems), parautochthonous (karst breccias), and allochthonous (such as fluvial cave sediments). The provenance of fluvial cave sediments is the landscape overlying the cave-karst system, and they are introduced to the cave-karst system by flood events. The Mississippian Leadville Limestone (SW Colorado) was subject to karst processes following Late Mississippian eustatic sea-level fall. These processes included formation of phreatic tubes, tower karst (kegelkarst), solution valleys (poljes), sinkholes (dolines), solution-enhanced joints (grikes), surficial flutes (rillenkarren), solution pans (kamenitzas), and breakout domes containing mosaic and crackle breccias. Flowstone, dripstone, and cave pearls are interbedded with karst breccias and fluvial cave sediments in the Leadville Limestone. The overlying Pennsylvanian Molas Formation is an eolian siltstone (dustite) with sediment sources from the peri-Gondwanan and Grenville rocks of eastern North America. Evidence that the fluvial cave sediments in the Leadville Limestone are derived from this dustite include compositional and textural matches, especially grain size distribution trends vertically downward from the former landscape surface. These grain size trends indicate infiltration of the

  6. Fluvial sediments characterization of Hornád river in its chosen parts (preliminary study

    Directory of Open Access Journals (Sweden)

    Stela Hanigovská

    2008-12-01

    Full Text Available Knowledge of main river sedimentary characteristics is very important source of information for next study or potentialcommercial usage of fluvial sediments. In paper is shown characterization of sediment distribution in chosen part of the river Hornád.Three main facial types were studied and described – gravel, sand and clay. Model created in this study shows that Hornád is a riverwith predominant gravel transport. This model also shows a sufficient amount of gravel for commercial use in some parts of the river.

  7. Arctic deltaic lake sediments as recorders of fluvial organic matter deposition

    Directory of Open Access Journals (Sweden)

    Jorien E Vonk

    2016-08-01

    Full Text Available Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, 13C, 14C and molecular organic geochemistry (lignin, leaf waxes. High-resolution age models (137Cs, 210Pb of downcore lake sediment records (n=11 along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels. Comparison with earlier published Mackenzie River depth profiles shows that (i lake sediments reflect the riverine surface suspended load, and (ii hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale riverine fluxes and may prove instrumental in shedding light on past behaviour of arctic rivers, as well as how they respond to a changing climate.

  8. Tropical Storms Control the Pulse of Fluvial Sediment Supplied to the Mekong Delta

    Science.gov (United States)

    Darby, S. E.; Hackney, C. R.; Leyland, J.; Best, J.; Parsons, D. R.; Kummu, M.; Lauri, H.; Nicholas, A. P.; Aalto, R. E.

    2016-02-01

    The world's largest rivers deliver 19 billion tonnes of sediment to the coastal zone annually, with a significant fraction sequestered in the large deltas that are home to 14% of the world's population. Most (>70%) of these large deltas are under threat from a combination of rising sea levels and ground surface subsidence, while the rivers that feed them have also been subjected to damming, substantially reducing the sediment supply that is available for delta (re)construction. In this paper we focus on the Mekong River as an exemplar of a large, tropical, fluvial dispersal system. Wuse new measurements of the suspended sediment load, combined with hydrological modelling, to reconstruct inter-annual variations in sediment load with and without tropical cyclones during the period 1981-2005. We examine in particular the results at Kratie in Cambodia, a gauging station that is located within 250 km of the apex of the Mekong delta. Our results indicate that fluvial sediment loads at Kratie have undergone a large and rapid decline (at a rate of 2 Mt/yr, reducing the annual sediment load in this period by 50%) during the study period. This is a remarkable finding, but we also show that this decline in sediment load is attributable almost entirely to a commensurate decline in the proportion of the Mekong's sediment load that is forced by tropical storms. Our results have profound implications. The Mekong's great delta, the rice basket of SE Asia, is home to 17 million people. A sustainable supply of fluvial sediment is critical in preventing the Mekong's delta being `drowned' by rising sea levels. In recent years attention has been focused on the likely deleterious effects of hydropower dam construction in the Mekong Basin on the future sediment loads reaching the delta. However, it is evident that the delivery of sediment from the Mekong River has already undergone a substantial reduction, similar in magnitude to that associated with future dam-induced trapping, as a

  9. The fluvial sediment budget of a dammed river (upper Muga, southern Pyrenees)

    Science.gov (United States)

    Piqué, G.; Batalla, R. J.; López, R.; Sabater, S.

    2017-09-01

    Many rivers in the Mediterranean region are regulated for urban and agricultural purposes. Reservoir presence and operation results in flow alteration and sediment discontinuity, altering the longitudinal structure of the fluvial system. This study presents a 3-year sediment budget of a highly dammed Mediterranean river (the Muga, southern Pyrenees), which has experienced flow regulation since the 1969 owing to a 61-hm3 reservoir. Flow discharge and suspended sediment concentration were monitored immediately upstream and downstream from the reservoir, whereas bedload transport was estimated by means of bedload formulae and estimated from regional data. Results show how the dam modifies river flow, reducing the magnitude of floods and shortening its duration. At the same time, duration of low flows increases. The downstream flow regime follows reservoir releases that are mostly driven by the irrigation needs in the lowlands. Likewise, suspended sediment and bedload transport are shown to be notably affected by the dam. Sediment transport upstream was mainly associated with floods and was therefore concentrated in short periods of time (i.e., > 90% of the sediment load occurred in sediments were transported more constantly (i.e., 90% of the load was carried during 50% of the time). Total sediment load upstream from the dam equalled 23,074 t, while downstream it was sediment load was equally distributed between suspension and bedload (i.e., 10,278 and 12,796 t respectively), whereas suspension dominated sediment transport downstream. More than 95% of the sediments transported from the upstream basins were trapped in the reservoir, a fact that explains the sediment deficit and the river bed armouring observed downstream. Overall, the dam disrupted the natural water and sediment fluxes, generating a highly modified environment downstream. Below the dam, the whole ecosystem shifted to stable conditions owing to the reduction of water and sediment loads.

  10. Short term development of a recently deglaciated proglacial slope (Gepatschferner/Tyrol) using SfM and LiDAR surveys

    Science.gov (United States)

    Smithgall, K.; Schuchardt, A.; Faust, M.; Morche, D.

    2015-12-01

    Quantifying sediment fluxes of proglacial regions is an important topic both to advance research, but also regional planning. The overarching goal of this research is to monitor the development of a proglacial slope of the Gepatschferner in the Tryol region of Austria. The Gepatschferner, the second largest glacier in Austria, has been retreating since the maximum of the Little Ice Age in 1850. The constant retreat continually exposes large quantities of glacial till which is then susceptible to hillslope and fluvial transport processes. Typically, data resolution and collection time are proportional; to obtain high resolution spatial datasets require significant fieldwork as well as additional data processing time. While utilization of either terrestrial or airborne LiDAR is one of the most common methods used to determine erosion and deposition of sediment at high resolution, several studies have shown that Structure from Motion photogrammetry is another tool available to generate similar quality data with significantly reduced fieldwork. The objective of this study is to determine the suitability and accuracy of using SfM to increase frequency of observation by comparing to terrestrial laser scanning data to determine the best data collection method to obtain both detailed spatial resolution as well as high temporal resolution for data in a proglacial environment. This study is part of the PROSA (High-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps) research project.

  11. Of ice and water: Quaternary fluvial response to glacial forcing

    Science.gov (United States)

    Cordier, Stéphane; Adamson, Kathryn; Delmas, Magali; Calvet, Marc; Harmand, Dominique

    2017-06-01

    Much research, especially within the framework of the Fluvial Archives Group, has focused on river response to climate change in mid-latitude non-glaciated areas, but research into the relationships between Quaternary glacial and fluvial dynamics remains sparse. Understanding glacial-fluvial interactions is important because glaciers are able to influence river behaviour significantly, especially during glacial and deglacial periods: (1) when they are located downstream of a pre-existing fluvial system and disrupt its activity, leading to hydrographical, hydrosedimentary and isostatic adjustments, and (2) when they are located upstream, which is a common scenario in mid-latitude mountains that were glaciated during Pleistocene cold periods. In these instances, glaciers are major water and sediment sources. Their role is particularly significant during deglaciation, when meltwater transfer towards the fluvial system is greatly increased while downstream sediment evacuation is influenced by changes to glacial-fluvial connectivity and basin-wide sediment storage. This means that discharge and sediment flux do not always respond simultaneously, which can lead to complex fluvial behaviour involving proglacial erosion and sedimentation and longer-term paraglacial reworking. These processes may vary spatially and temporally according to the position relative to the ice margin (ice-proximal versus ice-distal). With a focus on the catchments of Europe, this paper aims to review our understanding of glacial impacts on riversystem behaviour. We examine the methods used to unravel fluvial response to 'glacial forcing', and propose a synthesis of the behaviour of glacially-fed rivers, opening perspectives for further research.

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

    Science.gov (United States)

    Skov, Daniel S.; Egholm, David L.

    2016-04-01

    Surface erosion and sediment production seem to have accelerated globally as climate cooled in the Late Cenozoic, [Molnar, P. 2004, Herman et al 2013]. Glaciers emerged in many high mountain ranges during the Quaternary, and glaciation therefore represents a likely explanation for faster erosion in such places. Still, observations and measurements point to increases in erosion rates also in landscapes where erosion is driven mainly by fluvial processes [Lease and Ehlers (2013), Reusser (2004)]. Flume experiments and fieldwork have shown that rates of incision are to a large degree controlled by the sediment load of streams [e.g. Sklar and Dietrich (2001), Beer and Turowski (2015)]. This realization led to the formulation of sediment-flux dependent incision models [Sklar and Dietrich (2004)]. The sediment-flux dependence links incision in the channels to hillslope processes that supply sediment to the channels. The rates of weathering and soil transport on the hillslopes are processes that are likely to respond to changing temperatures, e.g. because of vegetation changes or the occurrence of frost. In this study, we perform computational landscape evolution experiments, where the coupling between fluvial incision and hillslope processes is accounted for by coupling a sediment-flux-dependent model for fluvial incision to a climate-dependent model for weathering and hillslope sediment transport. The computational experiments first of all demonstrate a strong positive feedback between channel and hillslope processes. In general, faster weathering leads to higher rates of channel incision, which further increases the weathering rates, mainly because of hillslope steepening. Slower weathering leads to the opposite result. The experiments also demonstrate, however, that the feedbacks vary significantly between different parts of a drainage network. For example, increasing hillslope sediment production may accelerate incision in the upper parts of the catchment, while at

  13. Fluvial landscapes evolution in the Gangkou River basin of southern Taiwan: Evidence from the sediment cores

    Science.gov (United States)

    Chen, Jia-Hong; Chyi, Shyh-Jeng; Yen, Jiun-Yee; Lin, Li-Hung; Yen, I.-Chin; Yu, Neng-Ti; Ho, Lih-Der; Jen, Chia-Hung

    2017-04-01

    The Gangkou River basin is the largest basin in the eastern Hengchun Peninsula of Taiwan. Its main river length is 31km and the basin area is 102sq. km. The width of the active channel is relatively narrow, but the valley from the middle to downstream is remarkably wide, indicating a feature of underfit stream. We drilled two sediment cores in the downstream area, including a 30m core (core-A) from a higher terrace, which is 14m above mean sea level, and a 20m core (core-B) from a lower terrace, which is 4m above mean sea level. Most of the sediments in the core-A are mud, which represents the flood plain facies, and 14C dates in the core-A range from 11ka to 7ka BP. Furthermore, the sediment layers reveal signals of marine events at the core depths of 5m to 11m by X-ray fluorescence. In the core-B, there is an erosional surface at the core depth of 5m. The age of the fluvial gravel layer above the erosional surface is about 0.4ka BP, and the mud layer top the surface is about 8.5ka BP. The preliminary results show that (1) as the tectonic uplift rate induced by the marine terraces around the basin is 1.0 to 2.5 mm/yr, and the accumulation rate of the mud layer in the basin is 6.7 to 8.7 mm/yr, the sediments infilling (more than 30-meters-thick) in the downstream area of the basin should be the results of the lower tectonic uplifting and the higher post-glacial sea level rise and; (2) the marine sediment layer with 14C dates of 7.5ka to 8.5ka BP is very likely the remain of the maximum flooding surface (MFS) in the early Holocene. These results indicate that the fluvial landscapes evolution of the basin was controlled by the sea-level; (3) the erosional surface in the core-B indicates the Gangkou River continuously erode the infilling sediments from 7ka to 0.4ka BP. Previous studies show that the sea-level around Taiwan gradually declined from its high stand since 6ka, we proposed that the continuous erosion was probably the results of tectonic uplifting and

  14. Stable carbon isotope analysis of fluvial sediment fluxes over two contrasting C(4) -C(3) semi-arid vegetation transitions.

    Science.gov (United States)

    Puttock, Alan; Dungait, Jennifer A J; Bol, Roland; Dixon, Elizabeth R; Macleod, Christopher J A; Brazier, Richard E

    2012-10-30

    Globally, many drylands are experiencing the encroachment of woody vegetation into grasslands. These changes in ecosystem structure and processes can result in increased sediment and nutrient fluxes due to fluvial erosion. As these changes are often accompanied by a shift from C(4) to C(3) vegetation with characteristic δ(13) C values, stable isotope analysis provides a promising mechanism for tracing these fluxes. Input vegetation, surface sediment and fluvially eroded sediment samples were collected across two contrasting C(4) -C(3) dryland vegetation transitions in New Mexico, USA. Isotope ratio mass spectrometric analyses were performed using a Carlo Erba NA2000 analyser interfaced to a SerCon 20-22 isotope ratio mass spectrometer to determine bulk δ(13) C values. Stable isotope analyses of contemporary input vegetation and surface sediments over the monitored transitions showed significant differences (p Pinus edulis/Juniperus monosperma (piñon-juniper) woodland sites. Significantly, this distinctive δ(13) C value was maintained in the bulk δ(13) C values of fluvially eroded sediment from each of the sites, with no significant variation between surface sediment and eroded sediment values. The significant differences in bulk δ(13) C values between sites were dependent on vegetation input. Importantly, these values were robustly expressed in fluvially eroded sediments, suggesting that stable isotope analysis is suitable for tracing sediment fluxes. Due to the prevalent nature of these dryland vegetation transitions in the USA and globally, further development of stable isotope ratio mass spectrometry has provided a valuable tool for enhanced understanding of functional changes in these ecosystems. Copyright © 2012 John Wiley & Sons, Ltd.

  15. Human impact on fluvial sediments: how to distinguish regional and local sources of heavy metals contamination

    Directory of Open Access Journals (Sweden)

    Novakova T.

    2013-04-01

    Full Text Available Regional contamination of southern Moravia (SE part of the Czech Republic by heavy metals and magnetic particles during the 20th century was quantified in fluvial sediments of the Morava River. The influence of local sources to the regional contamination of the river sediments and impact of sampling sites heterogeneity were studied in profiles with different sedimentology (facies and lithology. For this purpose, hundreds of samples were obtained from regulated channel banks and naturally inundated floodplains and proxy elementary analyses have been carried out by X-ray fluorescence spectroscopy (ED XRF, further calibrated by ICP MS. Magnetic susceptibility as a proxy of industrial contamination was determined and the age model has been obtained by 210Pb dating method. After establishing the lithological background from floodplain profiles, assessment of heavy metal contamination was done by using enrichment factors (EFs of heavy metals (Pb, Zn, Cu, Cr and magnetic susceptibility. Floodplain sedimentary profiles were found to be realiable for assessment of contamination and reconstruction of large scale, i.e. a really averaged regional contamination, while regulated channel banks are suitable for obtaining of more or less qualitative information of influence of local point sources in the area because sediments from regulated river banks qualitatively reflect the actual local contamination of the river system. It allowed us to distinguish the influence of local sources of contamination by comparing with more spatially averaged contamination signal from more distal floodplain profiles. The study area is rather weakly contaminated (EF ∼ 1-2, while individual sediment strata from regulated channel banks contains several times larger concentrations of heavy metals.

  16. Short-term geomorphological evolution of proglacial systems

    Science.gov (United States)

    Carrivick, Jonathan L.; Heckmann, Tobias

    2017-06-01

    Proglacial systems are amongst the most rapidly changing landscapes on Earth, as glacier mass loss, permafrost degradation and more episodes of intense rainfall progress with climate change. This review addresses the urgent need to quantitatively define proglacial systems not only in terms of spatial extent but also in terms of functional processes. It firstly provides a critical appraisal of prevailing conceptual models of proglacial systems, and uses this to justify compiling data on rates of landform change in terms of planform, horizontal motion, elevation changes and sediment budgets. These data permit us to produce novel summary conceptual diagrams that consider proglacial landscape evolution in terms of a balance of longitudinal and lateral water and sediment fluxes. Throughout, we give examples of newly emerging datasets and data processing methods because these have the potential to assist with the issues of: (i) a lack of knowledge of proglacial systems within high-mountain, arctic and polar regions, (ii) considerable inter- and intra-catchment variability in the geomorphology and functioning of proglacial systems, (iii) problems with the magnitude of short-term geomorphological changes being at the threshold of detection, (iv) separating short-term variability from longer-term trends, and (v) of the representativeness of plot-scale field measurements for regionalisation and for upscaling. We consider that understanding of future climate change effects on proglacial systems requires holistic process-based modelling to explicitly consider feedbacks and linkages, especially between hillslope and valley-floor components. Such modelling must be informed by a new generation of repeated distributed topographic surveys to detect and quantify short-term geomorphological changes.

  17. Soil and water temperature effects on the fluvial erosion of cohesive sediments

    Science.gov (United States)

    Akinola, A.; Wynn-Thompson, T.; Olgun, G.

    2016-12-01

    Sediment is one of the leading causes of water quality impairment in US streams and rivers (Wood and Armitage 1997; USEPA 2000; Bryce et al., 2010). Although sediment mobilization from the and transport through fluvial systems is a natural process, human activities, as a result of urbanization and climate change, alter the natural hydrologic and hydraulic characteristic of watersheds, leading to extreme erosion and sedimentation. Apart from higher flows, however, urbanization leads to elevated stream temperatures and, in combination with other anthropogenic influences such as hydropower operations, reservoir discharges and industrial cooling water, result in water and soil temperatures well above the expected seasonal temperature regime. In laboratory experiments, a higher water temperature was positively correlated with erosion rates (Grissinger, 1966; Cristensen and Das 1974; Parks, 2012) but this phenomenon is still poorly understood. Additionally, the effect of soil temperature on the fluvial erosion of cohesive soils has never been studied before; therefore, this research explores the relationship between soil and water temperature on cohesive soil erosion rate. Remolded montmorillonite, vermiculite and illite/kaolinite-dominated soils were tested in an 8 m x 1 m x 0.4 m recirculating flume at four combinations of soil temperatures and water temperatures (40C water and 40C soil, 40C water and 150C soil, 250C water and 250C soil, 250C water and 400C soil) representing typical winter and summer field conditions, as well as increased soil temperatures due to contact with urban infrastructure, such as bridge piers or foundations. Soils were compacted at their respective maximum dry density and optimum moisture content, based on Proctor tests (ASTM D698) and then eroded for 10-15 minutes at a boundary shear stress of 4 Pa. Velocity profiles and distance to the soil surface were measured continuously using a profiling acoustic doppler velocimeter. Differences in

  18. Recent changes in sediment redistribution in the upper parts of the fluvial system of European Russia: regional aspects

    Directory of Open Access Journals (Sweden)

    O. P. Yermolaev

    2015-03-01

    Full Text Available Quantitative assessments of soil loss from cultivated land and sediment redistribution along pathways from cultivated fields to river channels have been undertaken using a range of different methods and techniques, including erosion models, detailed studies of sediment redistribution in representative catchments, monitoring of gully head retreat and evaluation of sediment deposition in ponds and small reservoirs. Most of the sediment eroded from arable land is deposited between the lower portions of the cultivated slopes and the river channels. Less than 15% of the eroded sediment is delivered to the river channels. Sediment redistribution rates in the upper parts of the fluvial system have declined during the last 25 years in both the western and eastern parts of the Russian Plain, because of a major reduction of surface runoff during snowmelt and a reduction of the area of arable land in some parts of the study area.

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

    Science.gov (United States)

    Klebercz, Orsolya; Mayes, William M; Ánton, Aron Dániel; Feigl, Viktória; Jarvis, Adam P; Gruiz, Katalin

    2012-08-01

    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.

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

    Science.gov (United States)

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

    2008-07-01

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

  1. Fluvial sediment and chemical quality of water in the Little Blue River basin, Nebraska and Kansas

    Science.gov (United States)

    Mundorff, J.C.; Waddell, K.M.

    1966-01-01

    The Little Blue River drains about 3,37)0 square miles in south-central Nebraska and north-central Kansas. The uppermost bedrock in the basin is limestone and shale of Permian age and sandstone, shale, and limestone of Cretaceous age. Bedrock is exposed in many places in the lower one-third of the basin but elsewhere is buried beneath a thin to thick mantle of younger sediments, mostly of Quaternary age. These younger sediments are largely fluvial and eolian deposits but also include some glacial till. Consisting in large part of sand and gravel, the fluvial deposits are an important source of ground-water supplies throughout much of the upper two-thirds of the basin. Loess, an eolian deposit of clayey silt, is by far the most widespread surficial deposit. The climate is continental. Temperatures ranging from -38 ? F to 118 ? F have been recorded in the basin. Average annual precipitation as low as 10.31 and as high as 49.32 inches has been recorded. During most years in the period 1956-62, when nearly all the water-quality data were obtained, annual precipitation and annual runoff were greater than normal. Flow-duration data indicate, however, that the flow distribution for the period was near normal. The Little Blue River has the same suspended-sediment characteristics as nearly all unregulated streams in the Great Plains--a wide range in concentrations, low concentrations during low-flow periods, and high concentrations during almost all periods of significant overland runoff. The maximum instantaneous concentration normally occurs many hours before maximum water discharge during any given rise in stage; the maximum daily mean concentration during any given year normally occurs at a moderate stream stage, not during a major flood. Suspended-sediment data for Little Blue River near Deweese, Nebr., which receives drainage from the upstream third of the basin, approximately, show that during the 1!}57-61 water years concentrations of 100 ppm (parts per million) or

  2. Analytical Results for 42 Fluvial Tailings Cores and 7 Stream Sediment Samples from High Ore Creek, Northern Jefferson County, Montana

    Science.gov (United States)

    Fey, David L.; Church, Stan E.

    1998-01-01

    Metal-mining related wastes in the Boulder River basin study area in northern Jefferson County, Montana have been implicated in their detrimental effects on water quality with regard to acid-generation and toxic-metal solubility. Sediments, fluvial tailings and water from High Ore Creek have been identified as significant contributors to water quality degradation of the Boulder River below Basin, Montana. A study of 42 fluvial tailings cores and 7 stream sediments from High Ore Creek was undertaken to determine the concentrations of environmentally sensitive elements (i.e. Ag, As, Cd, Cu, Pb, Zn) present in these materials, and the mineral phases containing those elements. Two sites of fluvial deposition of mine-waste contaminated sediment on upper High Ore Creek were sampled using a one-inch soil probe. Forty-two core samples were taken producing 247 subsamples. The samples were analyzed by ICP-AES (inductively coupled-plasma atomic emission spectroscopy) using a total mixed-acid digestion. Results of the core analyses show that the elements described above are present at very high concentrations (to 22,000 ppm As, to 460 ppm Ag, to 900 ppm Cd, 4,300 ppm Cu, 46,000ppm Pb, and 50,000 ppm Zn). Seven stream-sediment samples were also analyzed by ICP-AES for total element content and for leachable element content. Results show that the sediment of High Ore Creek has elevated levels of ore-related metals throughout its length, down to the confluence with the Boulder River, and that the metals are, to a significant degree, contained in the leachable phase, namely the hydrous amorphous iron- and manganese-hydroxide coatings on detrital sediment particles.

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

    Science.gov (United States)

    Novakova, T.; Matys Grygar, T.; Bábek, O.; Faměra, M.; Mihaljevič, M.; Strnad, L.

    2012-04-01

    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 Zlín 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

  4. Coastal circulation and sediment dynamics in Hanalei Bay, Kaua'i, Hawaii: Part II: tracking recent fluvial sedimentation; isotope stratigraphy obtained in Summer 2005

    Science.gov (United States)

    Draut, Amy E.; Field, Michael E.; Bothner, Michael H.; Logan, Joshua B.; Casso, Michael A.; Baldwin, Sandra M.; Storlazzi, Curt D.

    2006-01-01

    Delivery and dispersal of fluvial sediment in Hanalei Bay, Kaua’i, Hawaii, have important implications for the health of local coral reefs. The reef community in Hanalei Bay represents a relatively healthy ecosystem. However, the reefs are periodically stressed by storm waves, and increases in sediment and dissolved substances from the Hanalei River have the potential to cause additional stress. Increased turbidity and sedimentation on corals during Hanalei River floods that occur in seasons of low wave energy, when sediment would not be readily remobilized and advected out of the bay, could affect the health and sustainability of coral reefs and the many associated species. Measurements of short-lived isotopes 7Be and 137Cs in sediment cores have been used to trace the thickness and distribution of terrestrial sediment in Hanalei Bay, in order to assess spatial and temporal patterns of sediment deposition and remobilization relative to coral-reef locations. A third isotope, 210Pb, derived primarily from seawater, provides additional information about recent sedimentary history. Isotope profiles and observations of sedimentary facies from cores collected at multiple locations in June 2005, and again in August 2005, indicate the presence of recent fluvial sediment and organic debris in the east part of the bay near the mouth of the Hanalei River. Away from the immediate vicinity of the river mouth, sediment in the uppermost 1 m below the sea floor had not retained a significant quantity of fluvial sediment within the eight months prior to either sampling effort. During the study interval in summer 2005 the Hanalei River had no major floods and there was relatively little sediment input to the bay. Sediment away from the river mouth was dominated by carbonate sand, although some terrestrial sediment was present in sub-sea-floor horizons. Sedimentary facies and isotope inventories throughout the bay showed substantial spatial heterogeneity. Sediment cores will be

  5. Open-water and under-ice seasonal variations in trace element content and physicochemical associations in fluvial bed sediment.

    Science.gov (United States)

    Doig, Lorne E; Carr, Meghan K; Meissner, Anna G N; Jardine, Tim D; Jones, Paul D; Bharadwaj, Lalita; Lindenschmidt, Karl-Erich

    2017-11-01

    Across the circumpolar world, intensive anthropogenic activities in the southern reaches of many large, northward-flowing rivers can cause sediment contamination in the downstream depositional environment. The influence of ice cover on concentrations of inorganic contaminants in bed sediment (i.e., sediment quality) is unknown in these rivers, where winter is the dominant season. A geomorphic response unit approach was used to select hydraulically diverse sampling sites across a northern test-case system, the Slave River and delta (Northwest Territories, Canada). Surface sediment samples (top 1 cm) were collected from 6 predefined geomorphic response units (12 sites) to assess the relationships between bed sediment physicochemistry (particle size distribution and total organic carbon content) and trace element content (mercury and 18 other trace elements) during open-water conditions. A subset of sites was resampled under-ice to assess the influence of season on these relationships and on total trace element content. Concentrations of the majority of trace elements were strongly correlated with percent fines and proxies for grain size (aluminum and iron), with similar trace element grain size/grain size proxy relationships between seasons. However, finer materials were deposited under ice with associated increases in sediment total organic carbon content and the concentrations of most trace elements investigated. The geomorphic response unit approach was effective at identifying diverse hydrological environments for sampling prior to field operations. Our data demonstrate the need for under-ice sampling to confirm year-round consistency in trace element-geochemical relationships in fluvial systems and to define the upper extremes of these relationships. Whether contaminated or not, under-ice bed sediment can represent a "worst-case" scenario in terms of trace element concentrations and exposure for sediment-associated organisms in northern fluvial systems

  6. The effects of sample scheduling and sample numbers on estimates of the annual fluxes of suspended sediment in fluvial systems

    Science.gov (United States)

    Horowitz, Arthur J.; Clarke, Robin T.; Merten, Gustavo Henrique

    2015-01-01

    Since the 1970s, there has been both continuing and growing interest in developing accurate estimates of the annual fluvial transport (fluxes and loads) of suspended sediment and sediment-associated chemical constituents. This study provides an evaluation of the effects of manual sample numbers (from 4 to 12 year−1) and sample scheduling (random-based, calendar-based and hydrology-based) on the precision, bias and accuracy of annual suspended sediment flux estimates. The evaluation is based on data from selected US Geological Survey daily suspended sediment stations in the USA and covers basins ranging in area from just over 900 km2 to nearly 2 million km2 and annual suspended sediment fluxes ranging from about 4 Kt year−1 to about 200 Mt year−1. The results appear to indicate that there is a scale effect for random-based and calendar-based sampling schemes, with larger sample numbers required as basin size decreases. All the sampling schemes evaluated display some level of positive (overestimates) or negative (underestimates) bias. The study further indicates that hydrology-based sampling schemes are likely to generate the most accurate annual suspended sediment flux estimates with the fewest number of samples, regardless of basin size. This type of scheme seems most appropriate when the determination of suspended sediment concentrations, sediment-associated chemical concentrations, annual suspended sediment and annual suspended sediment-associated chemical fluxes only represent a few of the parameters of interest in multidisciplinary, multiparameter monitoring programmes. The results are just as applicable to the calibration of autosamplers/suspended sediment surrogates currently used to measure/estimate suspended sediment concentrations and ultimately, annual suspended sediment fluxes, because manual samples are required to adjust the sample data/measurements generated by these techniques so that they provide depth-integrated and cross

  7. Valley-scale morphology drives differences in fluvial sediment budgets and incision rates during contrasting flow regimes

    Science.gov (United States)

    Weber, M. D.; Pasternack, G. B.

    2017-07-01

    High-resolution topographic surveys using LiDAR and multibeam sonar can be used to characterize and quantify fluvial change. This study used repeat surveys to explore how topographic change, fluvial processes, sediment budgets, and aggradation and incision rates vary across spatial scales and across two contrasting decadal flow regimes in a regulated gravel/cobble river. A novel method for quantifying digital elevation model uncertainty was developed and applied to a topographic change detection analysis from 2006/2008 to 2014. During this period, which had four modest 3-5 year floods, most sediment was laterally redistributed through bank erosion and channel migration. Erosion primarily occurred in the floodplain (97,000 m3), terraces (80,000 m3), and lateral bars (58,000 m3); while deposition occurred in the adjacent pools (73,000 m3), fast glides (48,000 m3), and runs (36,000 m3). In contrast, significantly higher magnitude and longer duration floods from 1999 to 2006/2008 caused sediment to be displaced longitudinally, with the upstream reaches exporting sediment and the downstream reaches aggrading. The river maintained floodplain connectivity during both periods, despite different processes dominating the type of connectivity. Larger floods promoted overbank scour and avulsion, while smaller floods promoted bank erosion and lateral migration. This study explores and illustrates how the geomorphic response to contrasting flood regimes in a nonuniform river is highly dependent on which landforms are controlling hydraulics.

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

    Science.gov (United States)

    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

    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 δD and δ13C 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 δD analysis given sample size (molecular sieve. A promising application of paleosol biomarkers is combining biomarker

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

    Science.gov (United States)

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

    2009-07-01

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

  10. The Spatial Distribution of Bed Sediment on Fluvial System: A Mini Review of the Aceh Meandering River

    Directory of Open Access Journals (Sweden)

    Muhammad Irham

    2016-08-01

    Full Text Available Dynamic interactions of hydrological and geomorphological processes in the fluvial system result in accumulated deposit on the bed because the capacity to carry sediment has been exceeded. The bed load of the Aceh fluvial system is primarily generated by mechanical weathering resulting in boulders, pebbles, and sand, which roll or bounce along the river bed forming temporary deposits as bars on the insides of meander bends, as a result of a loss of transport energy in the system. This dynamic controls the style and range of deposits in the Aceh River. This study focuses on the spatial distribution of bed-load transport of the Aceh River. Understanding the spatial distribution of deposits facilitates the reconstruction of the changes in controlling factors during accumulation of deposits. One of the methods can be done by sieve analysis of sediment, where the method illuminates the distribution of sediment changes associated with channel morphology under different flow regimes. Hence, the purpose of this mini review is to investigate how the sediment along the river meander spatially dispersed. The results demonstrate that channel deposits in the Aceh River are formed from four different type of materials: pebble deposited along upstream left bank; sand located on the upstream, downstream, and along meander belts; and silt and clay located along the cut bank of meander bends. Because of different depositional pattern, the distribution of the sediment along the river can be used as a surrogate to identify bank stability, as well as to predict critical geometry for meander bend initiation

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

    NARCIS (Netherlands)

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

    2010-01-01

    There is a long history of human–riverine interactions throughout the period of agriculture that in some regions of the world started several thousand years ago. These interactions have altered rivers to human dominated systems with often negative impacts on fluvial environments. To achieve a good

  12. Arctic deltaic lake sediments as recorders of fluvial organic matter deposition

    NARCIS (Netherlands)

    Vonk, J.E.; Dickens, A.F.; Giosan, L.; Hussain, Z.A.; Kim, B.; Zipper, S.C.; Holmes, R.M.; Montlucon, D.B.; Galy, V.; Eglinton, T.I.

    2016-01-01

    Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions.

  13. Connecting climate change to coastal evolution: Impact of sub-millenial- scale precipitation variability on fluvial sediment discharge

    Science.gov (United States)

    Krask, J. L.; Hein, C. J.; Galy, V.; FitzGerald, D.

    2016-12-01

    While millennial- scale variations in climate forcing drives changes in terrestrial processes, which are directly linked to fluvial sediment loads (e.g., weathering and erosion), the impact of decadal- to centennial- scale climate fluctuations on downstream coastal sedimentation patterns and landscape evolution remains unclear. Specifically, the connection between long-term (decades or more) precipitation seasonality and sediment export from river systems has not been established. This study examines the Tijucas strandplain (Southern Brazil) to determine if sub-millennial-scale fluctuations in precipitation at river systems have a detectable influence on the coastal landscape. A 5-km strandplain, formed over the last 5800 years through the rapid reworking of sediment discharged from the proximal Tijucas River in a regime of falling sea level, encompasses nearly 70 distinct transitions between shore-parallel sand- and mud- dominated facies. An overall shift from sand- to mud- dominance is due to a long-term reduction in wave energy caused by bay shoaling. Bulk and terrestrial vascular plant wax fatty acid stable hydrogen (δD) and carbon (δ13C) isotopic measurements from sediments from select sandy and muddy ridges across the plain reveal that these two sedimentological units are geochemically distinct. Furthermore, waxes from sediments deposited during periods of sandy progradation were, on average, >10‰ more enriched in deuterium than those from mud-dominated periods, indicating that these sedimentary units reflect different climatic conditions within the river drainage basin at the time of deposition. Comparison of plant wax isotopic signatures of river and beach sediments during the current period of mud-dominated progradation, reveals a close correlation with earlier periods of mud deposition within the Tijucas Strandplain. Thus, decadal- to centennial- scale sedimentologic transitions within the plain are interpreted to reflect climate-driven changes in mud

  14. Assessment of sediment sources throughout the proglacial area of a small Arctic catchment based on high-resolution digital elevation models

    Science.gov (United States)

    Kociuba, Waldemar

    2017-06-01

    The article presents calculations of quantitative modifications of the morphology of selected subsystems of a glacial valley through: (i) identification of the spatial distribution of important sources of sediment, (ii) assessment of the spatiotemporal variety of sediment volume and landform morphology, and (iii) assessment of the role of particular subsystems in sediment distribution. The study involved a comparison of the results of field measurements from 2010 to 2013 performed in the Scott Glacier catchment (10.1 km2) in NW Wedel Jarlsberg Land (Spitsbergen). The assessment of the landform surface changes was performed by means of a precise Terrestrial Laser Scanning (TLS) survey. The applied field and post-processing techniques for oblique laser scanning permitted the acquisition of digital elevation data at a resolution 0.01 m and density > 500 pt m- 2. This allowed the development of a detailed terrain model, and balancing spatial quantitative changes in six research test areas (10,000 m2) located within two subsystems of the catchment in a cascade arrangement. In the alluvial valley-floor subsystem, the survey covered: 1) the glacier terminus, 2) the intramarginal outwash plain, 3) the extramarginal braid-plain and 4) the alluvial fan, and in the slope subsystem: 5) the erosional-depositional slope in the gorge through terminal moraines, and 6) the solifluction slope. Three zones differing in terms of the spatiotemporal dynamics of geomorphic processes were distinguished within the two analysed valley subsystems. In the valley floor subsystem, these are: (i) the zone of basic supply (distribution throughout the melting season) and (ii) the redeposition zone (distribution particularly during floods), and in the slope subsystem: (iii) zone of periodical supply (distributed mainly in periods of increased precipitation and rapid increases in temperature in summer and during snow avalanches in winter). The glacier and the landforms of the channel and valley

  15. Influence of Sea Level Rise on Tidal Wetland Sediment and Carbon Accumulation Under Differing Fluvial Sediment Supply in the Pacific Northwest

    Science.gov (United States)

    Peck, E. K.; Wheatcroft, R. A.; Brophy, L.

    2016-12-01

    Despite their provision of numerous ecosystem services including blue carbon burial, the dominant factor - relative sea level rise (RSLR) or fluvial sediment supply - controlling the formation and growth of tidal wetlands remains debated. This uncertainty is due mainly to confounding variables, including tidal range, water temperature, and wetland plant assemblages; thus, comparisons within and amongst tidal wetlands are often equivocal. Estuaries in the Pacific Northwest, despite remaining understudied relative to US East and Gulf Coast and European estuaries, provide unique opportunities as natural laboratories because they exhibit enough commonalities for comparison yet maintain diversity in characteristics such as size, RSLR, and river discharge. To better understand the relative influences of RSLR and sediment supply on tidal wetland accretion, three estuaries in Oregon (Youngs Bay, Tillamook Bay, and Salmon River Estuary) of differing sediment supply but similar RSLR were chosen for analysis of sediment and carbon accumulation rates. Sediment cores were collected from the intertidal zone of each estuary and analyzed for sediment, mass, and carbon accumulation rates using 210Pb and 137Cs; CT-image-derived bulk density; and organic carbon analysis by loss on ignition and elemental analysis. Preliminary results indicate that though the three estuaries vary in mean annual discharge from 15 to 130 m3 s-1 and thus experience vastly different sediment loads, average sediment accumulation rates were 2.6 ± 0.6 (n = 5), 2.5 ± 0.3 (n = 4), and 2.9 ± 0.6 (n = 2) mm yr-1 for Youngs Bay, Tillamook Bay, and Salmon River Estuary respectively. Modern RSLR, which ranges from 0.7 ± 0.2 to 1.1 ± 0.2 mm yr-1 in these estuaries, appears to control marsh accretion rates.

  16. Streamflow and fluvial sediment transport in Pool C, restored section of the Kissimmee River: Chapter 2

    Science.gov (United States)

    Mossa, Joann; Gellis, Allen C.; Hupp, Cliff R.; Pearman, J. Leroy; Garfield, Ursula; Schenk, Edward R.; Rasmussen, Jim; Habermehl, Philip J.; Mossa, Joann; Valdes, Jose

    2009-01-01

    The Kissimmee River Restoration Project was authorized by Congress in 1992 to restore more than 64 km2 (square kilometers) of river/floodplain ecosystem including 69 km of meandering river channel and 10,900 hectares (ha) of wetlands. Although biologic monitoring is an integral and active part of the Kissimmee River restoration, by 2007 geomorphic monitoring that included sediment transport was lacking. In 2007, the U.S. Geological Survey (USGS) entered into a cooperative agreement with the South Florida Water Management District (SFWMD) to determine sediment transport characteristics of the restored section of the Kissimmee River in Pool C. Sediment transport characteristics that are monitored include suspended-sediment concentrations and loads, bedload, and bed material. In addition, the organic content of suspended sediment and bedload was determined. This chapter describes methods and results of the sediment transport monitoring from July 2007 through September 2008 in the Kissimmee River in Pool C.

  17. Fluvial bar dynamics in large meandering rivers with different sediment supply in the Amazon River basin

    Science.gov (United States)

    Monegaglia, Federico; Zolezzi, Guido; Tubino, Marco; Henshaw, Alex

    2017-04-01

    Sediments in the large meandering rivers of the Amazon basin are known to be supplied by sources providing highly different magnitudes of sediment input and storage, ranging from the sediment-rich Andean region to the sediment-poor Central Trough. Recent observations have highlighted how such differences in sediment supply have an important, net effect on the rates of planform activity of meandering rivers in the basin, in terms of meander migration and frequency of cutoffs. In this work we quantify and discuss the effect of sediment supply on the organization of macroscale sediment bedforms on several large meandering rivers in the Amazon basin, and we link our findings with those regarding the rates of planform activity. Our analysis is conducted through the newly developed software PyRIS, which enables us to perform extensive multitemporal analysis of river morphodynamics from multispectral remotely sensed Landsat imagery in a fully automated fashion. We show that large rivers with low sediment supply tend to develop alternate bars that consistently migrate through long reaches, characterized at the same time by limited planform development. On the contrary, high sediment supply is associated with the development of point bars that are well-attached to the evolving meander bends and that follow temporal oscillations around the bend apexes, which in turn show rapid evlution towards complex meander shapes. Finally, rivers with intermediate rates of sediment supply develop rather steady point bars associated with slowly migrating, regular meanders. We finally discuss the results of the image analysis in the light of the properties of river planform metrics (like channel curvature and width) for the examined classes of river reaches with different sediment supply rates.

  18. Metal content of road deposited sediment and fluvial channel-bed sediment in the City of Prince George, British Columbia, Canada

    Science.gov (United States)

    Owens, P. N.; Droppo, I. G.; Taylor, K. G.; Caley, K.; Campbell, S.; Rutherford, M.

    2010-12-01

    Over 50% of the global population live in urban centres and, therefore, an understanding of the processes acting upon urban systems is a global issue. The nature of human-made, often impervious, land surfaces and heavily engineered waterways results in hydrological and sedimentological systems in urbanised basins which contrast significantly to those within more natural (i.e. pristine, forested, agricultural) aquatic systems. In addition, the abundance of contamination sources in urban systems results in chemical pressures often manifested as high pollution concentrations or loadings which in turn have detrimental impacts on human and ecosystem health. We collected samples of road deposited sediment (RDS) and fluvial channel-bed sediment within the city of Prince George, British Columbia, in order to determine the metal content of the sediment within the urban landscape, and to investigate the link between the urban road surface and the urban river network, which flows into the Fraser River. Replicate samples of RDS were collected from street surfaces in fall 2008, summer 2009 and fall 2009, air-dried, and sieved into: 500-250 microns, 250-125 microns, 125-63 microns and <63 microns. We are currently undertaking a chemical sequential extraction to give detailed information on the metal speciation within the different size classes. Samples of channel bed sediment have also been analysed for total metal content. This presentation describes this work and presents preliminary results.

  19. Giant landslide deposits and the modalities of their removal by fluvial sediment export in the central Himalayas

    Science.gov (United States)

    Lave, Jerome; Lénard, Sébastien; Lanord, Christian France

    2017-04-01

    Slope failures and deep seated landslides are usually considered as the most efficient processes for hillslope erosion in active orogens. Erosion in the Narayani basin in central Himalaya (Nepal) confirms such assertion, with in addition the probable predominance of the very large landslides in the erosive budget of the range. In the High Himalayan part of this basin, a number of pluri-kilometric giant landslides have been described and involve up to ten cubic kilometres mass wasting (e.g. Weidinger et al., 2002). In this contribution, we discuss how the fluvial network do respond to such massive and sudden supply of debris, basing our analysis on several cases, documented by sedimentologic and geomorphologic observations, lithologic counting, geochemical tracing (down to the Ganga plain), and 14C or CRN dating. We first demonstrate that several massive fill terraces preserved along the Lesser Himalayan intramontane reaches are not climatically induced, but rather represent transient storage following giant landslide material export. Two types of deposits and therefore of sediment export modalities have been identified: either (1), as observed along a 100km long stretch of the Marsyandi river, through massive debris flow(s) runout following the break of a landslide-induced dam on main rivers, or (2) by the more gradual but efficient fluvial removal of the giant landslide deposits. In the second case, in particular when bedrock fracturing and crushing during landslide fall has strongly reduced the average debris size, because the steep Himalayan rivers are usually in strong over capacity or largely underloaded with fine to medium-size sediment, their can carry up to several cubic kilometres of sediments in one or two centuries. The coarsest part of the exported material is temporarily stored through aggradation in the massive Lesser Himalayan fill terraces because river gradient drops suddenly when river exits the High Himalaya, whereas the finest fraction is

  20. An Eulerian-Lagrangian description for fluvial coarse sediment transport: theory and verification with low-cost inertial sensors.

    Science.gov (United States)

    Maniatis, Georgios

    2017-04-01

    Fluvial sediment transport is controlled by hydraulics, sediment properties and arrangement, and flow history across a range of time scales. One reference frame descriptions (Eulerian or Lagrangian) yield useful results but restrict the theoretical understanding of the process as differences between the two phases (liquid and solid) are not explicitly accounted. Recently, affordable Inertial Measurement Units (IMUs) that can be embedded in coarse (100 mm diameter scale) natural or artificial particles became available. These sensors are subjected to technical limitations when deployed for natural sediment transport. However, they give us the ability to measure for the first time the inertial dynamics (acceleration and angular velocity) of moving sediment grains under fluvial transport. Theoretically, the assumption of an ideal (IMU), rigidly attached at the centre of the mass of a sediment particle can simplify greatly the derivation of a general Eulerian-Lagrangian (E-L) model. This approach accounts for inertial characteristics of particles in a Lagrangian (particle fixed) frame, and for the hydrodynamics in an independent Eulerian frame. Simplified versions of the E-L model have been evaluated in laboratory experiments using real-IMUs [Maniatis et. al 2015]. Here, experimental results are presented relevant to the evaluation of the complete E-L model. Artificial particles were deployed in a series of laboratory and field experiments. The particles are equipped with an IMU capable of recording acceleration at ± 400 g and angular velocities at ± 1200 rads/sec ranges. The sampling frequency ranges from 50 to 200 Hz for the total IMU measurement. Two sets of laboratory experiments were conducted in a 0.9m wide laboratory flume. The first is a set of entrainment threshold experiments using two artificial particles: a spherical of D=90mm (A) and an ellipsoid with axes of 100, 70 and 30 mm (B). For the second set of experiments, a spherical artificial enclosure of D

  1. Effect of Sediment Availability in Bedload-Dominated Rivers on Fluvial Geomorphic Equilibrium

    Science.gov (United States)

    Marti, M.

    2016-12-01

    Channels are known to compensate for changes in sediment supply via covariate changes in channel properties, yet the timescale for adjustment remains poorly constrained. We propose that reductions in sediment flux inhibit equilibrium re-establishment and thus impact the timescale of system adjustment. Using run-of-river dams as natural experiments, this study quantifies the geomorphic response of channels to sediment supply reduction. Channel traits that facilitate increased sediment trapping behind the dam, such as large reservoir storage capacity relative to annual inflow and low slope, were expected to inhibit a channel's ability to re-establish equilibrium following impoundment, lengthening the equilibrium establishment timescale to tens or hundreds of years. Reaches associated with increased trapping were therefore anticipated to exhibit non-equilibrium forms. Channel equilibrium was evaluated downstream of 8 ROR dams in New England with varying degrees of sediment trapping. Sites cover a range of watershed sizes (3-155 km2), channel slopes (.05-5%), 2-year discharges (1.5-60 m3/s) and storage capacity volumes. Because equilibrium channel form is just sufficient to mobilize grains under bankfull conditions in bedload-dominated rivers, the Shields parameter was used to assess equilibrium form. Unregulated, upstream Shields values and regulated, downstream values were calculated at 14 total cross-sections extending 300-450 m upstream and downstream of each dam. Sediment trapping was estimated using Brune's curve (1953). On the Charles Brown Brook (VT), a marginally significant (p=0.08) increase in Shields values from a mean of 0.14 upstream to 0.41 downstream of a 100+ year old dam was observed. In contrast, reaches downstream of the 100+ year old Pelham dam (MA) exhibit significantly lower Shields values. This suggests that trapping behind the dam inhibits the downstream channel from reaching an equilibrium state, but not always in the same way. Better

  2. Impact of fluvial sediment input to tidal amplification in an estuary

    Science.gov (United States)

    Wang, Zheng Bing; Fernández Bermejo, Mario

    2010-05-01

    Water level records at two stations in the Guadalquivir Estuary (Spain), one near the estuary mouth (Bonanza) and one about 70 km upstream (Seville), have been analysed to study the amplification of the tide in the estuary. The amplification factor, defined as the ratio between the amplitudes of the semi-diurnal tide at the two stations, show interesting temporal variations (See Figure 1). Firstly, a spring-neap variation is present showing that the tide is less amplified during spring tide than during neap tide. This can be explained by the stronger damping during spring tide due to the bottom resistance which increases non-linearly with the tidal flow velocity, indicating that bottom resistance is an important factor influencing the tidal amplification in the estuary. Secondly, the variation shows some spikes of extreme lows, which appear to be related to river floods causing a large difference between the mean water levels at the two stations. Thirdly, it is interesting to see that the amplification factor has a larger value during a number of periods, also after smoothing out the spring-neap variation. Further analysis of the data together with the data of turbidity and river discharges in combination with the results from various sediment transport modelling studies for the estuary reveals that this phenomenon is caused by the non-linear interaction between the tidal flow and suspended sediment transport, initiated by high sediment input from the river during a river flood. The high sediment concentration, up to more than 10 g/l, causes a reduction of the bottom resistance to the flow resulting in stronger tidal amplification in the estuary. The larger tidal amplitude causes higher tidal flow velocity which in turn keeps the suspended sediment concentration high. PIC Figure 1. Amplification factor of the semi-diurnal tide between Seville and Bonanza, daily data as well as the smoothed data after filtering out the spring-neap variation

  3. Basin-wide erosion rates of a relict surface in the southeastern Tibetan Plateau from in-situ produced 10Be in fluvial sediments

    Science.gov (United States)

    Fu, Ping; Stroeven, Arjen; Harbor, Jonathan; Heyman, Jakob; Caffee, Marc

    2017-04-01

    Over geological time Earth's surface undergoes radical changes. Few regions display these changes more than the Tibetan Plateau, a dynamic region undergoing changes brought about by tectonic and climatic forcing. Our goal is to quantify surface erosion rates on the Tibetan Plateau. Characterizing the surficial changes and the underlying causes are significant goals that require quantitative tools. With the development of AMS and improved understanding of nuclide production rates, in-situ produced cosmogenic nuclide dating has become increasingly effective for quantifying surface exposure age and erosion rates. Likewise, in-situ cosmogenic 10Be has been successfully to determine basin-wide erosion rates in many geological setting. However, quantifying fluvial erosion rates from glaciated basins using cosmogenic nuclide concentrations in fluvial sediments has limitations because burial by ice and glacial erosion can strongly reduce concentrations or entirely reset the cosmogenic nuclide clock in a landscape, which in turn leads to overestimation of fluvial erosion rates. In this study, we measured 10Be concentrations in river sand samples from both previously glaciated basins and non-glaciated basins, on a low-relief relict surface and the surrounding mountain area, respectively, in the southeastern Tibetan Plateau. The results show that fluvial sediments from glaciated basins have higher cosmogenic nuclide concentrations than expected given the deglaciation ages for these basins. Derived basin wide erosion rates are therefore significantly lower for glaciated basins than for non-glaciated basins. We interpret the high cosmogenic nuclide concentrations as a result of nuclide inheritance from before the last glaciation. In contrast to others studies indicating that overestimation of fluvial erosion rates can occur due to glacial erosion, our results suggest that in the case of a formerly glaciated relict surface in southeastern Tibet (largely preserved under non

  4. A model framework for fluvial-delta evolution that accounts for the accumulation of organic sediment

    Science.gov (United States)

    Lorenzo-Trueba, J.; Voller, V. R.; Paola, C.; Bevington, A.; Twilley, R.

    2011-12-01

    We extend current mass balance models for delta growth, in particular a simple geometric prism model, to couple the evolution of the delta plain with the accumulation of organic-rich sediment (i.e., peat). The key assumption is that the processes that control inorganic sedimentation and the burial of the organic matter always operate to preserve the self-similar geometry of the delta plain. In addition we account for the first order effect of salinity on the decomposition rate during shallow burial, and split the delta into a saline near-shore region and a fresh inland region. This leads to a model that can consistently account for the role of organic matter in determining delta growth dynamics under base-level rise, and pivot subsidence, in which the subsidence rate increases linearly from a fixed location. Previous analysis with the model has been able to explain the observed coupling between the accommodation/peat accumulation ratio and the quality of buried peat/coal deposits in the delta plain. Similarly to multiple modern and ancient organic-rich sedimentary environments, the model preserves the maximum volume fraction of organic sediment in the delta plain when the overall accommodation rate approximately equals the rate of peat accumulation. Here the emphasis is to investigate how the relative rate of peat accumulation plays into determining the dynamics of the delta growth. In particular it is shown that, in a pivot subsiding environment, an increase in peat accumulation in the inland region can enhance shoreline transgression. For a low peat accumulation the shoreline monotonically reaches a steady position, but as we increase the rate of peat accumulation in the fresh (inland) region the initial rapid advance of the shoreline is followed by a retreat and that monotonically approaching the steady location.

  5. Active biomonitoring for assessing effects of metal polluted sediment resuspension on gammarid amphipods during fluvial traffic.

    Science.gov (United States)

    Prygiel, E; Billon, G; François, A; Dumoulin, D; Chaumot, A; Geffard, O; Criquet, J; Prygiel, J

    2016-11-01

    The resuspension of polluted sediments by boat traffic could release substantial amounts of metals to the water column, affecting at the same time their bioavailability. In order to characterize the impact of sediment resuspensions on biota, caged amphipods have been deployed on three different channelized watercourses in Northern France. Firstly, the biological responses of transplanted freshwater gammarid amphipods, Gammarus fossarum, described by trace metal accumulation, feeding and reproduction activities were quite similar for the three water courses despite the differences of metal contamination and navigability. Secondly, the concentrations of metals accumulated in gammarids never exceeded the contamination thresholds previously defined for Co, Cu, Cr and Zn. Values were in the same order of magnitude whatever the studied site despite: (i) large differences noticed in the sediment quality and (ii) some concentrations in the overlying waters exceeding the Environmental Quality Standards (EQS) defined by the Water Framework Directive. Conversely, Pb was highly bioaccumulated with values systematically exceeding the threshold value whatever the site. Therefore, the impact of navigation cannot be proved and the difference between the 3 monitoring periods is rather attributed to environmental variability, probably linked to the seasonality. Moreover, this study also confirms that organisms sampled from a local population in the vicinity of the three studied watercourses could be used as test organisms, leading to similar results than the ones obtained with reference gammarids initially used for developing all the biological responses. This would simplify and then promote the development of studies based on gammarid amphipod, G. fossarum, as bioindicators. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Fault-block rotation controlling the distribution of fluvial sediments; a quantitative test on a Lower Pennsylvanian (Carboniferous) cyclothem succession

    NARCIS (Netherlands)

    van den Belt, Frank; de Boer, Poppe; van Bergen, Frank

    2015-01-01

    Depositional models of axial fluvial systems in half-grabens predict that the fluvial-sandstone percentage increases towards the down-thrown side of a fault, because channel systems tend to migrate to the area of maximum subsidence. This is at the expense of mudstone, but floodplain deposition

  7. Fluvial Sediments as GeoArchives in the Tsauchab Valley, Namibia

    Science.gov (United States)

    Völkel, Jörg; Bens, Oliver; Eden, Marie; Heine, Klaus; Hürkamp, Kerstin

    2015-04-01

    Understanding the history of how humans have interacted with the landscape can help clarify the options for managing our increasingly interconnected global system. In consequence of changing climate, major regional impacts on the human habitat is expected and must be addressed in modern land-use planning and management strategies which in turn has to rely on a diligent assessment of the nature of possible impacts on regional environments. In warm arid and semi-arid climatic zones, land use can result in landscape degradation, leading to enhanced activity of earth surface processes. Climatic changes can also be instrumental in producing landscape and ecosystem changes, similar to earth surface processes brought about by land-use change. However, predictions of the future behaviour of complex geo/bio-systems are limited, because these are open systems. Apart from modelling a promising approach to better understand the processes of environment responses is to learn lessons from past variability, i.e. searching for 'palaeo-analogue' situations. These are time intervals in the past with boundary conditions (e.g. sea-level changes, atmospheric circulation patterns) more similar to future scenarios than to the present day situation. Signals of these past climate and ecosystem changes are stored in a variety of natural continental and marine archives (sediments, biogens). These geoarchives have the potential for providing researchers with high-resolution data for the reconstruction of palaeo-ecosystems and their dynamics. The influence of key forcing variables and their effects extracted from the geoarchives will be cross-checked in order to validate and adjust models of present and future processes. This knowledge will help justify and calibrate prognostic scenarios in order to deliver proxy-data for southern-hemisphere records. - The project "GeoArchives" is funded by BMBF within the SPACES-Program.

  8. Numerical analysis of palynological data from Neogene fluvial sediments as evidence for rainforest dynamics in western Amazonia

    Science.gov (United States)

    Salamanca, Sonia; van Manen, Milan; Hoorn, Carina

    2014-05-01

    Deep-time records that give an insight into the composition and dynamics of the ancestral Amazon rain forest are rare. Yet to understand the modern biodiversity patterns it is important to untangle the long-term evolution of this forest. Sampling Neogene strata requires drilling operations or complex fieldwork along the rivers where outcrops generally are small. In the nineties an exceptionally good exposure of fluvial sediments of early Miocene age (17.7-16.1 Ma) was documented near the island of Mariñame (Caquetá River, Colombian Amazonia) (Hoorn, 1994). This 60 m sediment succession consists of quartz-rich sands with a circa 10 m black, sandy clay intercalation. Palynomorphs are well preserved in these organic-rich clays and palynological analysis indicated high pollen diversity and changes in composition following changes in the sedimentary environment and water composition (see van Soelen et al., this session). A numerical analysis in R (2013) of the existing data, using a number of multivariate and other statistical techniques now shows a gradient of change in the composition of the Miocene palynological assemblages. Non-metric-multidimensional scaling using distance matrixes (Oksanen, 2012) and their visualizations in correlograms (Friendly, 2002) indicate that the regional (palm) swamp forests of Mauritiides franciscoi (Mauritia), frequently found together with other palms such as Psilamonocolpites amazonicus (Euterpe?) and Psilamonocolpites rinconii, were affected by a marine incursion. The latter is suggested by the change of composition and the presence of estuarine elements such as Zonocostites ramonae (Rhizophora), foraminifer linings and dinoflagellate cysts, which became common during the marine event. In the older part of the section, and at the top, Rhoipites guianensis (Sterculiaceae/Tiliaceae) is quite abundant, in contrast with the relatively low abundance of M. franciscoi. The numerical analysis allowed us to: a) group the pollen data into 3

  9. Fluvial export of radionuclides: impact on sediment storages of the Rhone River and fluxes towards the Mediterranean Sea; Transfert des radionucleides artificiels par voie fluviale: consequences sur les stocks sedimentaires rhodaniens et les exports vers la Mediterranee

    Energy Technology Data Exchange (ETDEWEB)

    Rolland, B

    2006-02-15

    This study deals with the behaviour of trace contaminants originating from chronic liquid releases within fluvial aquatic systems. It focuses on some particle reactive artificial radionuclides that were released by the Marcoule nuclear fuel reprocessing plant during several years mainly prior the end of the nineties and that are still detected in the lower Rhone river. It underlines the decrease of {sup 137}Cs, {sup 238}Pu and {sup 239+240}Pu fluxes to the Mediterranean Sea in relation with the variations in the chronic liquid releases from Marcoule. The role of flood events on radionuclides exports processes is particularly considered. Over the years 2002 to 2004, floods contributed for 67%, 55%, 68%, 49% and 56% of the mean annual fluxes of {sup 137}Cs, {sup 238}Pu and {sup 239+240}Pu and natural {sup 7}Be et {sup 210}Pbxs, although these events only represented 5% of time. The removal, during floods, of sediments contaminated by the Marcoule releases contributes on the average for 19%, 44% and 22% of the annual exports of {sup 137}Cs, {sup 238}Pu and {sup 239+240}Pu towards the Sea. Thus, such sedimentary stocks act as a delayed source term of artificial radioactivity that is currently significant. Determination of the sediments residence times before removal allows to evaluate the Rhone capacity to clear its contaminated stocks. Residence times of 200 years, 100 years and 900 years are estimated to be necessary to totally remove the accumulated {sup 137}Cs, {sup 238}Pu and {sup 239+240}Pu, respectively. The location typologies of sediment storages within fluvial systems are also specified. These location are represented on one hand by dams, and on the other hand by river banks and oxbow lakes. Stocks accumulated in dams seem to be removed more easily than those trapped in banks. (author)

  10. A first look at the influence of anthropogenic climate change on the future delivery of fluvial sediment to the Ganges-Brahmaputra-Meghna delta.

    Science.gov (United States)

    Darby, Stephen E; Dunn, Frances E; Nicholls, Robert J; Rahman, Munsur; Riddy, Liam

    2015-09-01

    We employ a climate-driven hydrological water balance and sediment transport model (HydroTrend) to simulate future climate-driven sediment loads flowing into the Ganges-Brahmaputra-Meghna (GBM) mega-delta. The model was parameterised using high-quality topographic data and forced with daily temperature and precipitation data obtained from downscaled Regional Climate Model (RCM) simulations for the period 1971-2100. Three perturbed RCM model runs were selected to quantify the potential range of future climate conditions associated with the SRES A1B scenario. Fluvial sediment delivery rates to the GBM delta associated with these climate data sets are projected to increase under the influence of anthropogenic climate change, albeit with the magnitude of the increase varying across the two catchments. Of the two study basins, the Brahmaputra's fluvial sediment load is predicted to be more sensitive to future climate change. Specifically, by the middle part of the 21(st) century, our model results suggest that sediment loads increase (relative to the 1981-2000 baseline period) over a range of between 16% and 18% (depending on climate model run) for the Ganges, but by between 25% and 28% for the Brahmaputra. The simulated increase in sediment flux emanating from the two catchments further increases towards the end of the 21(st) century, reaching between 34% and 37% for the Ganges and between 52% and 60% for the Brahmaputra by the 2090s. The variability in these changes across the three climate change simulations is small compared to the changes, suggesting they represent a significant increase. The new data obtained in this study offer the first estimate of whether and how anthropogenic climate change may affect the delivery of fluvial sediment to the GBM delta, informing assessments of the future sustainability and resilience of one of the world's most vulnerable mega-deltas. Specifically, such significant increases in future sediment loads could increase the resilience

  11. A History of Pebbles and Silt – Fluvial Sediment Transport, Hydropower and Technical Expertise at the Austrian Danube and its Tributaries

    Directory of Open Access Journals (Sweden)

    Schoder Angelika

    2016-08-01

    Full Text Available The paper investigates experts’ perceptions of hydropower, sediment regime, and their interaction in the 20th century with an environmental historical approach, based on various case studies at both the Danube River and one of its tributaries, and on a review of contemporary literature authored by engineers. Results show that questions of sediment continuity have engaged planners of hydropower plants since the advent of this technology, and decisions were at any time influenced by multiple interests (navigation, electricity demand, nature conservation. In such an intricate fluvial landscape, phenomena like reservoir sedimentation and riverbed incision can be approached as “legacies” of past technical interventions, which limit the options of current and future river management.

  12. River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

    Directory of Open Access Journals (Sweden)

    Manon Besset

    2017-09-01

    Full Text Available The Mediterranean basin (including the Black Sea is characterized by a plethora of deltas that have developed in a wave-influenced setting. Many of these deltas are sourced in sediments by river catchments that have been variably dammed. The vulnerability status of a selection of ten deltas subject to different levels of reduction in fluvial sediment supply following damming was analysed by quantifying changes in delta protrusion area and protrusion angle over the last 30 years. The rationale for choosing these two metrics, which do not require tricky calculations of longshore bedload transport volumes and river ‘influence’, is that as sediment supply wanes, increasing relative efficiency of waves leads to longshore redistribution of reworked sediments and progressive ‘flattening’ of the delta protrusion. The results show that eight of the ten deltas (Nile, Rhône, Ebro, Ceyhan, Arno, Ombrone, Moulouya, Medjerda are in erosion, whereas two (Danube, Po show stability, but the statistical relationship between change in delta protrusion area and sediment flux reduction is poor, thus suggesting that the role of dams in causing delta shoreline erosion may have been over-estimated. But this poor relationship could also be due to a long temporal lag between dam construction and bedload removal and transport to the coast downstream of dams, and, where the delta protrusion is being eroded, to bedload trapping by shoreline engineering structures and by elongating delta-flank spits. Other potential influential factors in shoreline change include subsidence, sea-level rise, storminess, exceptional river floods, and managed sediment releases downstream of dams. A longer observation period and high-resolution sediment-budget studies will be necessary to determine more definitively to which extent continued trapping of sediment behind dams will impact overall delta stability in the Mediterranean and Black Seas. Mitigation of delta erosion is likely to

  13. Human Land Use and Land Abandonment Greatly Impacted Sedimentation Rates and Fluvial Styles Since the Iron Age in the Valdaine (Southern France)

    Science.gov (United States)

    Notebaert, B.; Berger, J. F.

    2015-12-01

    In this study we present the Holocene time differentiated sediment budget for the Valdaine region (334 km²) and its main streams (Roubion and Jabron, totaling 610 km²). Sediment budget studies have been used previously in western and central Europe to quantify the changing sediment dynamics under climatic variations and changes in human land use. This study is one of the first attempts to quantify such Holocene sediment dynamics in southern Europe. We achieved a more detailed chronology than comparable European sediment budgets, by combining traditional geomorphology with geo-archaeological research. The results demonstrate that total colluvial deposition is high in comparison with catchments in temperate Europe, while alluvial deposition falls within the range of those other studies. High colluvial deposition values are explained by the long intensive land use in this region, combined with a Mediterranean climate. The temporal evolution of sediment deposition shows a pattern of three main deposition phases alternating with three phases of hillslope stability and valley incision. Intensive human land use in the lower fertile parts of the region is responsible for the deposition phases, while land abandonment caused hillslope stability and valley incision. The first major peaks in soil erosion occurred during the Iron Age and Roman Period, with rates about half as high as for the last 800 years. In addition to these variations in sedimentation rates, there occurred also major variations in sediment texture and fluvial style. During most of the Holocene rivers had a meandering pattern and deposited silty and clayey sediments. But major sedimentation peaks during the Roman Period and especially since the 12th century coincided with the establishment of a braided river and deposition of gravel and sand. These changes in river style demonstrate how the montane headwaters become an important sediment source. It remains an open question whether this is only related to

  14. Stratigraphic architecture, bedload extraction, and mass balance of Holocene fluvial sediments in a tectonically subsiding basin within the Ganges-Brahmaputra River delta, Bangladesh

    Science.gov (United States)

    Sincavage, R.; Goodbred, S. L., Jr.; Pickering, J.; Wilson, C.; Paola, C.; Hossain, S.; Steckler, M. S.; Seeber, L.

    2014-12-01

    The Brahmaputra River occupied the tectonically active Sylhet Basin in eastern Bangladesh three times during the Holocene. With samples from more than 200 closely-spaced (3-5 km) boreholes, we take advantage of these discrete channel occupations and the high trapping efficiency of the subsiding basin to investigate dispersal of fluvial sediments. Experiment and theory suggest that depositional units transition from channels to lobes as transported sediment mass declines below ~30% of the total measured at the basin head. We test these ideas by reconstructing the geometry and grain size distributions of a large (30 m thick x 80 km wide) sand lobe formed during the mid-Holocene occupation (~7000-4000 years BP) of Sylhet Basin. Based on estimates of modern sediment discharge in the system, the volume of this sediment lobe is insufficient to account for the entire sediment budget. The smaller sediment volume is likely a consequence of reduced sediment discharge during a weakened monsoon. Additional sediment is likely to have also been routed out of the basin via an outlet located approximately along the modern Meghna River channel. Facies within Sylhet Basin can be characterized as stacked braidbelt sands in the proximal portion of the system, with isolated sand lenses further downstream, indicating a transition from a highly mobile braidbelt to a less mobile distributary system. The majority of bed load is extracted within a distance of ~150 km from the avulsion node, approximately coincident with the regional backwater reach of the Bengal Basin, suggesting a link between the hydraulic and "morphodynamic" backwater reaches of the system. Downstream fining is more rapid in sediments associated with the long-term occupation of Sylhet Basin, for which sediment is trapped over a relatively short distance within the sand wedge of central Sylhet Basin, than those from the early- and late-Holocene occupations, for which sediment is distributed over a longer path that follows

  15. Occurrence, compositional distribution, and toxicity assessment of pyrethroid insecticides in sediments from the fluvial systems of Chaohu Lake, Eastern China.

    Science.gov (United States)

    Wang, Ji-Zhong; Bai, Ya-Shu; Wu, Yakton; Zhang, Shuo; Chen, Tian-Hu; Peng, Shu-Chuan; Xie, Yu-Wei; Zhang, Xiao-Wei

    2016-06-01

    Surface sediment-associated synthetic pyrethroid insecticides (SPs) are known to pose high risks to the benthic organisms in Chaohu Lake, a shallow lake of Eastern China. However, the pollution status of the lake's tributaries and estuaries is still unknown. The present study was conducted to investigate the occurrence, compositional distribution, and toxicity of 12 currently used SPs in the surface sediments from four important tributaries, as well as in the sediment cores at their estuaries, using GC-MS for quantification. All SPs selected were detectable, with cypermethrin, es/fenvalerate, and permethrin dominant in both surface and core sediments, suggesting that these compounds were extensively applied. Urban samples contained the highest summed concentrations of the 12 SPs analyzed (Σ12SP) in both surface and core sediments compared with rural samples, suggesting that urban areas near aquatic environments posed high risks for SPs. The mean concentration of Σ12SP in surface sediments of each river was generally higher than that found in core sediments from its corresponding estuary, perhaps implying recent increases in SP usage. Surface sediments were significantly dominated by cypermethrin and permethrin, whereas core sediments were dominated by permethrin and es/fenvalerate. The compositional distributions demonstrated a spatial variation for surface sediments because urban sediments generally contained greater percentages of permethrin and cypermethrin, but rural sediments had significant levels of es/fenvalerate and cypermethrin. In all sediment cores, the percentage of permethrin gradually increased, whereas es/fenvalerate tended to decrease, from the bottom sediments to the top, indicating that the former represented fresh input, whereas the latter represented historical residue. Most urban samples would be expected to be highly toxic to benthic organisms due to the residue of SPs based on a calculation of toxic units (TUs) using toxicity data of the

  16. Accumulation of heavy metals and trace elements in fluvial sediments received effluents from traditional and semiconductor industries.

    Science.gov (United States)

    Hsu, Liang-Ching; Huang, Ching-Yi; Chuang, Yen-Hsun; Chen, Ho-Wen; Chan, Ya-Ting; Teah, Heng Yi; Chen, Tsan-Yao; Chang, Chiung-Fen; Liu, Yu-Ting; Tzou, Yu-Min

    2016-09-29

    Metal accumulation in sediments threatens adjacent ecosystems due to the potential of metal mobilization and the subsequent uptake into food webs. Here, contents of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and trace elements (Ga, In, Mo, and Se) were determined for river waters and bed sediments that received sewage discharged from traditional and semiconductor industries. We used principal component analysis (PCA) to determine the metal distribution in relation to environmental factors such as pH, EC, and organic matter (OM) contents in the river basin. While water PCA categorized discharged metals into three groups that implied potential origins of contamination, sediment PCA only indicated a correlation between metal accumulation and OM contents. Such discrepancy in metal distribution between river water and bed sediment highlighted the significance of physical-chemical properties of sediment, especially OM, in metal retention. Moreover, we used Se XANES as an example to test the species transformation during metal transportation from effluent outlets to bed sediments and found a portion of Se inventory shifted from less soluble elemental Se to the high soluble and toxic selenite and selenate. The consideration of environmental factors is required to develop pollution managements and assess environmental risks for bed sediments.

  17. Accumulation of heavy metals and trace elements in fluvial sediments received effluents from traditional and semiconductor industries

    Science.gov (United States)

    Hsu, Liang-Ching; Huang, Ching-Yi; Chuang, Yen-Hsun; Chen, Ho-Wen; Chan, Ya-Ting; Teah, Heng Yi; Chen, Tsan-Yao; Chang, Chiung-Fen; Liu, Yu-Ting; Tzou, Yu-Min

    2016-09-01

    Metal accumulation in sediments threatens adjacent ecosystems due to the potential of metal mobilization and the subsequent uptake into food webs. Here, contents of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) and trace elements (Ga, In, Mo, and Se) were determined for river waters and bed sediments that received sewage discharged from traditional and semiconductor industries. We used principal component analysis (PCA) to determine the metal distribution in relation to environmental factors such as pH, EC, and organic matter (OM) contents in the river basin. While water PCA categorized discharged metals into three groups that implied potential origins of contamination, sediment PCA only indicated a correlation between metal accumulation and OM contents. Such discrepancy in metal distribution between river water and bed sediment highlighted the significance of physical-chemical properties of sediment, especially OM, in metal retention. Moreover, we used Se XANES as an example to test the species transformation during metal transportation from effluent outlets to bed sediments and found a portion of Se inventory shifted from less soluble elemental Se to the high soluble and toxic selenite and selenate. The consideration of environmental factors is required to develop pollution managements and assess environmental risks for bed sediments.

  18. Comparison of fluvial suspended-sediment concentrations and particle-size distributions measured with in-stream laser diffraction and in physical samples

    Science.gov (United States)

    Czuba, Jonathan A.; Straub, Timothy D.; Curran, Christopher A.; Landers, Mark N.; Domanski, Marian M.

    2015-01-01

    Laser-diffraction technology, recently adapted for in-stream measurement of fluvial suspended-sediment concentrations (SSCs) and particle-size distributions (PSDs), was tested with a streamlined (SL), isokinetic version of the Laser In-Situ Scattering and Transmissometry (LISST) for measuring volumetric SSCs and PSDs ranging from 1.8-415 µm in 32 log-spaced size classes. Measured SSCs and PSDs from the LISST-SL were compared to a suite of 22 datasets (262 samples in all) of concurrent suspended-sediment and streamflow measurements using a physical sampler and acoustic Doppler current profiler collected during 2010-12 at 16 U.S. Geological Survey streamflow-gaging stations in Illinois and Washington (basin areas: 38 – 69,264 km2). An unrealistically low computed effective density (mass SSC / volumetric SSC) of 1.24 g/ml (95% confidence interval: 1.05-1.45 g/ml) provided the best-fit value (R2 = 0.95; RMSE = 143 mg/L) for converting volumetric SSC to mass SSC for over 2 orders of magnitude of SSC (12-2,170 mg/L; covering a substantial range of SSC that can be measured by the LISST-SL) despite being substantially lower than the sediment particle density of 2.67 g/ml (range: 2.56-2.87 g/ml, 23 samples). The PSDs measured by the LISST-SL were in good agreement with those derived from physical samples over the LISST-SL's measureable size range. Technical and operational limitations of the LISST-SL are provided to facilitate the collection of more accurate data in the future. Additionally, the spatial and temporal variability of SSC and PSD measured by the LISST-SL is briefly described to motivate its potential for advancing our understanding of suspended-sediment transport by rivers.

  19. Investigating how fundamental parameters of XRF sample preparation and analysis affect the observed elemental concentration: an experiment using fluvial sediment from Sabah, Borneo.

    Science.gov (United States)

    Higton, Sam; Walsh, Rory

    2015-04-01

    X-Ray Fluorescence (XRF) is an important technique for measuring the concentrations of geochemical elements and inorganic contaminants adsorbed to sediments as an input to sediment tracing methods used to evaluate sediment transport dynamics in river catchments. In addition to traditional laboratory-based XRF instruments, the advent of increasingly advanced portable handheld XRF devices now mean that samples of fluvial sediment can be analysed in the field or in the laboratory following appropriate sample preparation procedures. There are limitations and sources of error associated with XRF sample preparation and analysis, however. It is therefore important to understand how fundamental parameters involved in sample preparation and analysis, such as sample compression and measurement exposure duration, affect observed variability in measurement results. Such considerations become important if the resulting measurement variability is high relative to the natural variability in element concentrations at a sample site. This paper deployed a simple experimental design to assess the impacts of varying a number of sample preparation and XRF analysis parameters on recorded measurements of elemental concentrations of the fine fraction (plastic sample cups were used for both the Rigaku laboratory machine and the Niton portable XRF machine. A computer-controlled desktop laboratory stand was used in conjunction with the Niton handheld XRF analyser to ensure consistent repeated measurements. Parameters investigated related to sample preparation included consistent mechanical compression of samples within the sample cup and film thickness. Parameters investigated related to XRF analysis included the XRF machine selected and measurement exposure duration. As XRF is a non-destructive technique, wherever possible the same sample material was used to test different parameters, so as to reduce variations due to the heterogeneous nature of sediment. Observed XRF measurements

  20. Chemical data and lead isotopic compositions of geochemical baseline samples from streambed sediments and smelter slag, lead isotopic compositions in fluvial tailings, and dendrochronology results from the Boulder River watershed, Jefferson County, Montana

    Science.gov (United States)

    Unruh, Daniel M.; Fey, David L.; Church, Stan E.

    2000-01-01

    IntroductionAs a part of the U.S. Geological Survey Abandoned Mine Lands Initiative, metal-mining related wastes in the Boulder River study area in northern Jefferson County, Montana, have been evaluated for their environmental effects. The study area includes a 24-km segment of the Boulder River in and around Basin, Montana and three principal tributaries to the Boulder River: Basin Creek, Cataract Creek, and High Ore Creek. Mine and prospect waste dumps and mill wastes are located throughout the drainage basins of these tributaries and in the Boulder River. Mine-waste material has been transported into and down streams, where it has mixed with and become incorporated into the streambed sediments. In some localities, mine waste material was placed directly in stream channels and was transported downstream forming fluvial tailings deposits along the stream banks. Water quality and aquatic habitat have been affected by trace-element-contaminated sediment that moves from mine wastes into and down streams during snowmelt and storm runoff events within the Boulder River watershed.Present-day trace element concentrations in the streambed sediments and fluvial tailings have been extensively studied. However, in order to accurately evaluate the impact of mining on the stream environments, it is also necessary to evaluate the pre-mining trace-element concentrations in the streambed sediments. Three types of samples have been collected for estimation of pre-mining concentrations: 1) streambed sediment samples from the Boulder River and its tributaries located upstream from historical mining activity, 2) stream terrace deposits located both upstream and downstream of the major tributaries along the Boulder River, and 3) cores through sediment in overbank deposits, in abandoned stream channels, or beneath fluvial tailings deposits. In this report, we present geochemical data for six stream-terrace samples and twelve sediment-core samples and lead isotopic data for six terrace

  1. Fluvial Apophenia

    Science.gov (United States)

    Coulthard, Tom; Armitage, John

    2017-04-01

    Apophenia describes the experience of seeing meaningful patterns or connections in random or meaningless data. Francis Bacon was one of the first to identify its role as a "human understanding is of its own nature prone to suppose the existence of more order and regularity in the world than it finds". Examples include pareidolia (seeing shapes in random patterns), gamblers fallacy (feeling past events alter probability), confirmation bias (bias to supporting a hypothesis rather than disproving), and he clustering illusion (an inability to recognise actual random data, instead believing there are patterns). Increasingly, researchers use records of past floods stored in sedimentary archives to make inferences about past environments, and to describe how climate and flooding may have changed. However, it is a seductive conclusion, to infer that drivers of landscape change can lead to changes in fluvial behaviour. Using past studies and computer simulations of river morphodynamics we explore how meaningful the link between drivers and fluvial changes is. Simple linear numerical models would suggest a direct relation between cause and effect, despite the potential for thresholds, phase changes, time-lags and damping. However, a comparatively small increase in model complexity (e.g. the Stream Power law) introducing non-linear behaviour and Increasing the complexity further can lead to the generation of time-dependent outputs despite constant forcing. We will use this range of findings to explore how apophenia may manifest itself in studies of fluvial systems, what this can mean and how we can try to account for it. Whilst discussed in the context of fluvial systems the concepts and inferences from this presentation are highly relevant to many other studies/disciplines.

  2. Characterizing landscape-scale erosion using 10Be in detrital fluvial sediment: Slope-based sampling strategy detects the effect of widespread dams

    Science.gov (United States)

    Reusser, Lucas J.; Bierman, Paul R.; Rizzo, Donna M.; Portenga, Eric W.; Rood, Dylan H.

    2017-05-01

    Concentrations of in situ 10Be measured in detrital fluvial sediment are frequently used to estimate long-term erosion rates of drainage basins. In many regions, basin-averaged erosion rates are positively correlated with basin average slope. The slope dependence of erosion allows model-based erosion rate estimation for unsampled basins and basins where human disturbance may have biased cosmogenic nuclide concentrations in sediment. Using samples collected from southeastern North America, we demonstrate an approach that explicitly considers the relationship between average basin slope and erosion rate. Because dams and reservoirs are ubiquitous on larger channels in the field area, we selected 36 undammed headwater subbasins (average area 10.6 km2) from which we collected river sand samples and measured 10Be concentrations. We used these data to train a predictive model that relates average basin slope and 10Be-inferred erosion rate. Applying our model to 28 basins in the same region previously studied with 10Be, we find that the model successfully predicts erosion rates for basins of different sizes if they are undammed or if samples were collected >25 km downstream of dams. For samples collected closer to dams, measured erosion rates exceed modeled erosion rates for two-thirds of the samples. In three of four cases where paired samples were collected upstream of reservoirs and downstream of the impounding dam, 10Be concentrations were lower downstream. This finding has implications for detrital cosmogenic studies, whether or not samples were collected directly downstream of dams, because dams obstruct most major rivers around the world, effectively trapping sediment that originated upstream.

  3. Spatial patterns of D/H ratios in meteoric water, leaf waxes from plants, POM and sediments within a large fluvial Himalayan catchment

    Science.gov (United States)

    Sachse, D.; Hoffmann, B.; Bookhagen, B.; Feakins, S. J.; Kahmen, A.; Adhikari, D. P.

    2012-12-01

    The Arun Valley in eastern Nepal exhibits one of the steepest climatic gradients in the world with several meters of annual rainfall at the mountain front in the south and arid, cold conditions near the Tibetan Plateau in the north. This provides an excellent natural laboratory to analyse the spatial distribution of hydrogen isotope (D/H) ratio of meteoric waters and of plant leaf waxes in living plants, particulate organic matter (POM) and sediments within a catchment. The D/H ratio of leaf wax in soils and lake sediments has been shown to be a robust proxy of general hydrological conditions. Since substantial heterogeneity is observed between individual plants, long-term archives, such as soils and sediments are spatially and temporally integrating proxy records. In order to extract quantitative information from biological proxies in long-term sedimentary archives, it is important to understand these integrative processes expected with fluvial transport, but so far detailed catchment wide surveys of proxy heterogeneity are lacking. Here we studied the Nepalese part of the catchment of the Arun river, whose southern part is strongly affected by the summer precipitation associated with the Indian monsoon, whereas the upper reaches to the north are glacier-fed. We sampled across a steep altitudinal (73 to 1267m a.s.l.) and environmental gradient with spatially variable precipitation (from 800-4500 mm/year) and five different vegetation zones (from tropical to subtropical evergreen forests and finally alpine vegetation) along the less than 150 km the valley cuts through the Himalaya. We investigated how this gradient is recorded in the D/H ratio of water and/or leaf wax from different natural archives (meteoric water, plants, particulate organic material, soils, river sediments). We compare this dataset with climatological, ecological and remote sensing data from their respective catchments to evaluate sources of the observed heterogeneity. In particular, our aim is

  4. Delivery and fate of fluvial water and sediment to the sea: a marine geologist's view of European rivers

    Directory of Open Access Journals (Sweden)

    John D. Milliman

    2001-12-01

    Full Text Available Despite their relatively small drainage areas, European rivers reflect a wide variety of hydrologic regimes, although with very few exceptions they have been strongly affected by human activity. Scandinavian rivers (particularly those draining Iceland and western Norway can have high runoff, and, except for those draining Iceland, all have very low suspended and dissolved sediment loads. Northern and western European rivers have somewhat lower runoff, among the lowest suspended sediment yields in the world, and anthropogenically enhanced dissolved solid loads. Annual discharge of many of these rivers appears to vary inversely with the North Atlantic Oscillation index. Rivers discharging from the southern Alps into the Mediterranean Sea have relatively high runoff, high suspended sediment yields (reflecting younger, more easily erodable rocks as well as generally smaller drainage basins, and high dissolved yields, although presumably with somewhat less human influence. European rivers and their estuaries tend to reflect the terrestrial environments of their drainage basins (i.e. climate, landscape geomorphology, geology, but they also display strong anthropogenic signatures. Sediment erosion increased dramatically in the last several millenia in response to deforestation, farming and mining. In the past 50 years, however, increased soil conservation and local reversion of agricultural land to forest, as well as river diversion and dam construction, have decreased the suspended sediment loads of many European rivers. Improved mining and manufacturing techniques, as well as more effective use of fertilizers and improved waste treatment, almost surely will result in lower dissolved solids and nutrient fluxes to the coastal environments, which presently are the highest in the world. The long-range effects of changed land use on estuarine and coastal environments remain to be seen, although decreased sediment loads in the past 20-40 years have already

  5. Termination of fluvial-alluvial sedimentation in the Xining Basin, NE Tibetan Plateau, and its subsequent geomorphic evolution

    Science.gov (United States)

    Weilin, Zhang; Tao, Zhang; Chunhui, Song; Appel, Erwin; Ziqiang, Mao; Yahui, Fang; Yin, Lu; Qingquan, Meng; Rongsheng, Yang; Dawen, Zhang; Bingshuai, Li; Jiao, Li

    2017-11-01

    The Xining Basin in northern China lies topographically in the transitional zone between the Tibetan Plateau and the Loess Plateau, and climatically in the transitional zone between humid East Asia and the arid Asian interior. During the Cenozoic, the basin accumulated a thick, continuous sequence of fluviolacustrine-dominated red beds and subsequent eolian loess. The termination of sediment deposition in the Xining Basin is the key to understanding its subsequent evolution, the development of the modern Yellow River, and the history of dust deposition. Here we present the results of a detailed paleomagnetic study of the upper sedimentary sequence of the Xining Basin below the river terraces, and in addition we review previous studies of river evolution development. Our results indicate that the age of the uppermost part of the continuous sequence of fluviolacustrine-dominated red beds in the Xining Basin ranges from ca. 20 Ma to 4.8 Ma, suggesting that basin sedimentation ended at the earliest at 4.8 Ma, and they also provide an earliest age constraint for the subsequent river terrace development and eolian dust deposition. In addition, these results demonstrate that the termination of sedimentation in the Xining Basin and the nearby Linxia Basin was approximately coeval, suggesting the rapid regional tectonic uplift of the NE Tibetan Plateau and resulting reorganization of the landforms and development of the paleo-Yellow River in the late Pliocene.

  6. Fluvial geomorphological response along the upland sediment cascade during the record-breaking December 2015 floods, Cumbria, UK

    Science.gov (United States)

    Russell, Andrew; Perks, Matthew; Large, Andrew; Dunning, Stuart; Warburton, Jeff

    2016-04-01

    Between 0900 GMT on 4th December and 0900 GMT on 6th December 2015, Atlantic Storm Desmond produced over 260 mm of rainfall in Cumbria, northwest England, representing a new UK 48 hour rainfall maximum, and breaking previous records set in 2005 and 2009. The December 2015 event resulted in a number of rivers significantly exceeding their 2009 levels, over-topping recently-commissioned flood defences, destroying bridges and flooding thousands of homes. Our research aim is to identify factors controlling significant geomorphological and sedimentary response during Storm Desmond along the upland sediment cascade including: Rattling Beck (Glenridding), a high gradient upland stream draining the flanks of Helvellyn (950 m.a.o.d.), and a 25km extended reach of the lower gradient piedmont Derwent River corridor downstream of Bassenthwaite Lake. Rattling Beck descends steeply from the eastern slopes of the Helvellyn massif draining across an alluvial fan into Lake Ullswater. On 5th December 2015 the village of Glenridding was severely impacted by flooding which deposited boulder-sized sediment within the centre of the village, completely blocking the pre-existing stream course and causing avulsion of waning stage flows through riverside properties. A major new sediment lobe was deposited on the existing alluvial fan downstream of the village, grading to the temporarily raised lake water level. Although a number of hillslope failures occurred in the higher catchment, the majority of the sediment transported by Rattling Beck and impacting the village was acquired within a 2km reach upstream of Glenridding through erosion of older glacial and alluvial sediments. Lateral channel erosion was enhanced by inability of flood flows to rework highly resistant boulder bar lag deposits related to a previous mine tailings dam failure in 1927. The River Derwent corridor extends for 30km downstream of Bassenthwaite Lake to the Irish Sea at Workington and has a sinuous course ranging in

  7. Laser-diffraction and pipette-method grain size of Dutch sediments: correlations for fine fractions of marine, fluvial, and loess samples

    NARCIS (Netherlands)

    Buurman, P.; Paper, T.; Reijneveld, J.A.; Jong, de F.; Gelder, van E.

    2001-01-01

    To evaluate correlations between silt and clay fractions determined by pipette method and laser diffraction, samples from Dutch fine marine, fluvial, and loess deposits were analysed by both methods. For fluvial deposits, correlations for fractions 50 µm were excellent (R2 > 0.95), those for 2-4,

  8. Temperature signal in suspended sediment export from an Alpine catchment

    Science.gov (United States)

    Costa, Anna; Molnar, Peter; Stutenbecker, Laura; Bakker, Maarten; Silva, Tiago A.; Schlunegger, Fritz; Lane, Stuart N.; Loizeau, Jean-Luc; Girardclos, Stéphanie

    2018-01-01

    Suspended sediment export from large Alpine catchments ( > 1000 km2) over decadal timescales is sensitive to a number of factors, including long-term variations in climate, the activation-deactivation of different sediment sources (proglacial areas, hillslopes, etc.), transport through the fluvial system, and potential anthropogenic impacts on the sediment flux (e.g. through impoundments and flow regulation). Here, we report on a marked increase in suspended sediment concentrations observed near the outlet of the upper Rhône River Basin in the mid-1980s. This increase coincides with a statistically significant step-like increase in basin-wide mean air temperature. We explore the possible explanations of the suspended sediment rise in terms of changes in water discharge (transport capacity), and the activation of different potential sources of fine sediment (sediment supply) in the catchment by hydroclimatic forcing. Time series of precipitation and temperature-driven snowmelt, snow cover, and ice melt simulated with a spatially distributed degree-day model, together with erosive rainfall on snow-free surfaces, are tested to explore possible reasons for the rise in suspended sediment concentration. We show that the abrupt change in air temperature reduced snow cover and the contribution of snowmelt, and enhanced ice melt. The results of statistical tests show that the onset of increased ice melt was likely to play a dominant role in the suspended sediment concentration rise in the mid-1980s. Temperature-driven enhanced melting of glaciers, which cover about 10 % of the catchment surface, can increase suspended sediment yields through an increased contribution of sediment-rich glacial meltwater, increased sediment availability due to glacier recession, and increased runoff from sediment-rich proglacial areas. The reduced extent and duration of snow cover in the catchment are also potential contributors to the rise in suspended sediment concentration through

  9. Sedimentary environment and paleosols of middle Miocene fluvial and lacustrine sediments in central Japan: Implications for paleoclimate interpretations

    Science.gov (United States)

    Hatano, Nozomi; Yoshida, Kohki

    2017-01-01

    Sedimentary facies analysis and description of paleosols were carried out for the middle Miocene Tokiguchi Porcelain Clay Formation (PCF) in central Japan in order to interpret the soil-forming environments during a long hiatus in the Japanese Islands. The sedimentary facies suggests that deposition occurred mainly in a lacustrine environment, with minor channel-fill and debris-flow deposits associated with alluvial fan environments. The coarse-grained sediments, which are inferred to have been deposited in channel-bar and debris-flow deposits, are present only in the marginal area of the sedimentary basin. Mature paleosols are identified in the Tokiguchi PCF, characterized by illuviated clay, identifiable soil horizons including Bt horizons and many in situ plant fossils, and are then similar to Ultisols. Most tree trunk fossils, however, were preserved by burial beneath debris-flow deposits. Most of paleosols formed on lacustrine deposits and were covered by lacustrine clay and silt deposits, without intervening coarse-grained deposits, such as flood-flow deposits. This change of sedimentary facies indicates a dramatic change of hydrologic environment, from stagnant water to entirely desiccated conditions, promoting weathering and soil formation. The relationship between sedimentary facies and Pedotypes, consequently, implies the repetition of specific events, i.e., submergence and emergence of lake bottom, most likely due to formation and drainage of a dammed lake. These isolated events and development of mature paleosols might suggest specific characteristics of middle Miocene weathering conditions, such as seasonally heavy rainfall and/or warm climatic conditions in the Japanese Islands.

  10. Substantial export of suspended sediment to the global oceans from glacial erosion in Greenland

    Science.gov (United States)

    Overeem, I.; Hudson, B. D.; Syvitski, J. P. M.; Mikkelsen, A. B.; Hasholt, B.; van den Broeke, M. R.; Noël, B. P. Y.; Morlighem, M.

    2017-11-01

    Limited measurements along Greenland's remote coastline hamper quantification of the sediment and associated nutrients draining the Greenland ice sheet, despite the potential influence of river-transported suspended sediment on phytoplankton blooms and carbon sequestration. Here we calibrate satellite imagery to estimate suspended sediment concentration for 160 proglacial rivers across Greenland. Combining these suspended sediment reconstructions with numerical calculations of meltwater runoff, we quantify the amount and spatial pattern of sediment export from the ice sheet. We find that, although runoff from Greenland represents only 1.1% of the Earth's freshwater flux, the Greenland ice sheet produces approximately 8% of the modern fluvial export of suspended sediment to the global ocean. Sediment loads are highly variable between rivers, consistent with observed differences in ice dynamics and thus with control by glacial erosion. Rivers that originate from deeply incised, fast-moving glacial tongues form distinct sediment-export hotspots: just 15% of Greenland's rivers transport 80% of the total sediment load of the ice sheet. We conclude that future acceleration of melt and ice sheet flow may increase sediment delivery from Greenland to its fjords and the nearby ocean.

  11. Black carbon contributes to organic matter in young soils in the Morteratsch proglacial area (Switzerland

    Directory of Open Access Journals (Sweden)

    E. Eckmeier

    2013-03-01

    Full Text Available Most glacier forefields of the European Alps are being progressively exposed since the glaciers reached their maximum expansion in the 1850s. Global warming and climate changes additionally promote the exposure of sediments in previously glaciated areas. In these proglacial areas, initial soils have started to develop so that they may offer a continuous chronosequence from 0 to 150-yr-old soils. The build-up of organic matter is an important factor of soil formation, and not only autochthonous but also distant sources might contribute to its accumulation in young soils and surfaces of glacier forefields. Only little is known about black carbon in soils that develop in glacier forefields, although charred organic matter could be an important component of organic carbon in Alpine soils. The aim of our study was to examine whether black carbon (BC is present in the initial soils of a proglacial area, and to estimate its relative contribution to soil organic matter. We investigated soil samples from 35 sites distributed over the whole proglacial area of Morteratsch (Upper Engadine, Switzerland, covering a chronosequence from 0 to 150 yr. BC concentrations were determined in fine earth using the benzene polycarboxylic acid (BPCA marker method. We found that charred organic matter occurred in the whole area, and that it was a main compound of soil organic matter in the youngest soils, where total Corg concentrations were very low. The absolute concentrations of BC in fine earth were generally low but increased in soils that had been exposed for more than 40 yr. Specific initial microbial communities may profit from this additional C source during the first years of soil evolution and potentially promote soil development in its early stage.

  12. Implications of sediment transport by subglacial water flow for interpreting contemporary glacial erosion rates

    Science.gov (United States)

    Beaud, Flavien; Flowers, Gwenn E.; Venditti, Jeremy G.

    2017-04-01

    The role of glaciers in landscape evolution is central to the interactions between climate and tectonic forces at high latitudes and in mountainous regions. Sediment yields from glacierized basins are used to quantify contemporary erosion rates on seasonal to decadal timescales, often under the assumption that subglacial water flow is the main contributor to these yields. Two recent studies have furthermore used such sediment fluxes to calibrate a glacial erosion rule, where erosion rate scales with ice sliding speed raised to a power greater than one. Subglacial sediment transport by water flow has however seldom been studied, thus the controls on sediment yield from glacierized basins remain enigmatic. To bridge this gap, we develop a 1-D model of morphodynamics in semi-circular bedrock-floored subglacial channels. We adapt a sediment conservation law from the fluvial literature, developed for both mixed bedrock / alluvial and alluvial conditions, to subglacial channels. Channel evolution is a function of the traditional melt-opening due to viscous heat dissipation from the water flow, and creep closure of the overlying ice, to which we add the closure or enlargement due to sediment deposition or removal, respectively. Using a simple ice geometry representing a land-terminating glacier, we find that the shear stresses produced by the water flow on the bed decrease significantly near the terminus. As the ice thins, creep closure decreases and large hydraulic potential gradients cannot be sustained. The resulting gradients in sediment transport lead to a bottleneck, and sediment accumulates if the sediment supply is adequate. A similar bottleneck occurs if a channel is well established and water discharge drops. Whether such constriction happens in space of time, in the presence of a sufficiently large sediment supply sediment accumulates temporarily near the terminus, followed shortly thereafter by enhanced sediment transport. Reduction in the cross-sectional area

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

    NARCIS (Netherlands)

    Tebbens, L.A.

    1999-01-01

    All fluvial systems ultimately drain into alluvial basins, where the weathering products of their upstream drainage areas accumulate over a time-span varying from 10 0to 10 6years. Most silted-up alluvial basins are low-gradient deltas that are

  14. Influences of Holocene sea level, regional tectonics, and fluvial, gravity and slope currents induced sedimentation on the regional geomorphology of the continental slope off northwestern India

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Almeida, F.

    Regional geomorphology derived from echosounding and bathymetric data (lines of a total of 12,000 km), depth to basement, regional deep seated tectonic features, surficial sediment distribution and Holocene sedimentation rates of the continental...

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

    Directory of Open Access Journals (Sweden)

    Claire Cousins

    2015-02-01

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

  16. Petrology and provenance of the Neogene fluvial succession in Pishin Belt (Katawaz Basin) western Pakistan: Implications for sedimentation in peripheral forelands basins

    DEFF Research Database (Denmark)

    Kasi, Aimal Khan; Kassi, Aktar Muhammad; Friis, Henrik

    2017-01-01

    Sandstones and conglomerates of the Neogene fluvial succession in Pishin Belt (Katawaz Basin), Pakistan were studied for the first time to understand the composition, provenance and tectonic settings of the source areas. Sandstones of the Miocene Dasht Murgha Group and Pliocene Malthanai Formation...... Formation and Pleistocene Bostan formation reveal that the Eocene Nisai Formation and Oligocene Khojak Formation, within the Pishin Belt, were the main source terrains while the Muslim Bagh-Zhob Ophiolite and the Cretaceous and Jurassic succession of the Indian Plate were subordinate source terrains...

  17. Assessing the continuity of the upland sediment cascade, fluvial geomorphic response of an upland river to an extreme flood event: Storm Desmond, Cumbria, UK.

    Science.gov (United States)

    Joyce, Hannah; Hardy, Richard; Warburton, Jeff

    2017-04-01

    Hillslope erosion and accelerated lake sedimentation are often viewed as the source and main storage elements in the upland sediment cascade. However, the continuity of sediment transfer through intervening valley systems has rarely been evaluated during extreme events. Storm Desmond (4th - 6th December, 2015) produced record-breaking rainfall maximums in the UK: 341.4 mm rainfall was recorded in a 24 hour period at Honister Pass, Western Lake District, and 405 mm of rainfall was recorded in a 38 hour period at Thirlmere, central Lake District. The storm was the largest in a 150 year local rainfall series, and exceeded previous new records set in the 2005 and 2009 floods. During this exceptional event, rivers over topped flood defences, and caused damage to over 257 bridges, flooded over 5000 homes and businesses, and caused substantial geomorphic change along upland rivers. This research quantifies the geomorphic and sedimentary response to Storm Desmond along a regulated gravel-bed river: St John's Beck. St John's Beck (length 7.8 km) is a channelised low gradient river (0.005) downstream of Thirlmere Reservoir, which joins the River Greta, and flows through Keswick, where major flooding has occurred, before discharging into Bassenthwaite Lake. St John's Beck has a history of chronic sediment aggradation, erosion and reports of historic flooding date back to 1750. During Storm Desmond, riverbanks were eroded, coarse sediment was deposited across valuable farmland and access routes were destroyed, including a bridge and footpaths, disrupting local business. A sediment budget framework has been used to quantify geomorphic change and sedimentary characteristics of the event along St John's Beck. The volume and sediment size distribution of flood deposits, channel bars, tributary deposits, floodplain scour, riverbank erosion and in-channel bars were measured directly in the field and converted to mass using local estimates of coarse and fine sediment bulk densities

  18. Correlation between river sediment type and trace metal content; Correlacion entre la naturaleza de un sedimento fluvial y el contenido en metales traza

    Energy Technology Data Exchange (ETDEWEB)

    Pinto Ganfornina, J.; Galindo riao, M.D.; Martinez, M.P.; Garcia-Vargas, M. [Departamento de Quimica Analitica Facultad de ciencias, Universidad de Cadiz, Cadiz (Spain)

    1996-04-01

    The organic contamination caused by municipal and food industry waste makes the waters of the river Guadalete in Cadiz, Spain, quite insalubrious. It wast therefore thought useful to determine whether there is also contamination resulting from heavy metals in the river bed sediment coming from these efluents. four sampling points along the river were selected and the Cu, Ni, Zn; Pb and Cd contents of the sediment determined. The results were used to established correlations between the trace elements found and the type of sediment with a view to evaluating possible metal-induced contamination and its origin. (Author) 14 refs.

  19. Martian fluvial conglomerates at Gale Crater

    Science.gov (United States)

    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, Horton E.; Dromart, G.; Palucis, M.C.; Yingst, R.A.; Anderson, Ryan B.; Herkenhoff, K. E.; Le Mouélic, S.; Goetz, W.; Madsen, M.B.; Koefoed, A.; Jensen, J.K.; Bridges, J.C.; Schwenzer, S.P.; Lewis, K.W.; Stack, K.M.; Rubin, D.; Kah, L.C.; Bell, J.F.; Farmer, J.D.; Sullivan, R.; Van Beek, T.; Blaney, D.L.; Pariser, O.; Deen, R.G.

    2013-01-01

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

  20. Feeding the hungry river: Fluvial morphodynamics and the entrainment of artificially inserted sediment at the dammed river Isar, Eastern Alps, Germany

    Science.gov (United States)

    Heckmann, Tobias; Haas, Florian; Abel, Judith; Rimböck, Andreas; Becht, Michael

    2017-08-01

    Dams interrupt the sediment continuum in rivers by retaining the bedload; combined with flow diversion, bedload retention in tributaries and river engineering measures, this causes a bedload deficit leading to changes in river planform and morphodynamics, with potentially detrimental downstream effects. As part of the SedAlp joint project (Sediment management in Alpine basins: integrating sediment continuum, risk mitigation and hydropower), this study investigates changes within a section of the dammed river Isar between the Sylvenstein reservoir and the city of Bad Tölz. We use a multi-method approach on a range of spatial and temporal scales. First, we analysed historical maps and aerial photos to analyse river planform and landcover changes within the river corridor of the whole study area on a temporal scale of over 100 years. Results show that major changes occurred before the construction of the Sylvenstein reservoir, suggesting that present morphodynamics represent the reaction to different disturbances on different time scales. Second, changes in mean bed elevation of cross profiles regularly surveyed by the water authorities are analysed in light of artificial sediment insertion and floods; they are also used to estimate the sediment budget of river reaches between consecutive cross profiles. Results suggest stability and a slight tendency towards incision, especially near the Sylvenstein reservoir; further downstream, the sediment balance was positive. Third, we acquired multitemporal aerial photos using an unmanned aerial vehicle and generated high-resolution digital elevation models to show how sediment artificially inserted in the river corridor is entrained. Depending on the position of the artificial deposits in relation to the channel, the deposits are entrained during floods of different return periods.

  1. Fluvial geomorphology and suspended-sediment transport during construction of the Roanoke River Flood Reduction Project in Roanoke, Virginia, 2005–2012

    Science.gov (United States)

    Jastram, John D.; Krstolic, Jennifer L.; Moyer, Douglas; Hyer, Kenneth

    2015-09-30

    Beginning in 2005, after decades of planning, the U.S. Army Corps of Engineers (USACE) undertook a major construction effort to reduce the effects of flooding on the city of Roanoke, Virginia—the Roanoke River Flood Reduction Project (RRFRP). Prompted by concerns about the potential for RRFRP construction-induced geomorphological instability and sediment liberation and the detrimental effects these responses could have on the endangered Roanoke logperch (Percina rex), the U.S. Geological Survey (USGS) partnered with the USACE to provide a real-time warning network and a long-term monitoring program to evaluate geomorphological change and sediment transport in the affected river reach. Geomorphological change and suspended-sediment transport are highly interdependent and cumulatively provide a detailed understanding of the sedimentary response, or lack thereof, of the Roanoke River to construction of the RRFRP.

  2. Signatures and significance of aeolian, fluvial, bacterial and diagenetic magnetic mineral fractions in Late Quaternary marine sediments off Gambia, NW Africa

    NARCIS (Netherlands)

    Just, A.; Dekkers, M.J.; Dobeneck, T. von; Hoesel, A. van; Bickert, T.

    Two gravity cores retrieved off NW Africa at the border of arid and subtropical environments (GeoB 13602–1 and GeoB 13601–4) were analyzed to extract records of Late Quaternary climate change and sediment export. We apply end-member (EM) unmixing to 350 acquisition curves of isothermal remanent

  3. Sudden disintegration of ice in the glacial-proglacial transition zone of the largest glacier in Austria

    Science.gov (United States)

    Kellerer-Pirklbauer, Andreas; Avian, Michael; Hirschmann, Simon; Lieb, Gerhard Karl; Seier, Gernot; Sulzer, Wolfgang; Wakonigg, Herwig

    2017-04-01

    Rapid deglaciation does not only reveal a landscape which is prone to rapid geomorphic changes and sediment reworking but also the glacier ice itself might be in a state of disintegration by ice melting, pressure relief, crevasse formation, ice collapse or changes in the glacier's hydrology. In this study we considered the sudden disintegration of glacier ice in the glacial-proglacial transition zone of Pasterze Glacier. Pasterze Glacier is a typical alpine valley glacier and covers currently some 16.5 km2 making it to the largest glacier in Austria. This glacier is an important site for alpine mass tourism in Austria related to a public high alpine road and a cable car which enable access to the glacier rather easily also for unexperienced mountaineers. Spatial focus in our research is given on two particular study areas where several ice-mass movement events occurred during the 2015- and 2016-melting seasons. The first study area is a crevasse field at the lower third of the glacier tongue. This lateral crevasse field has been substantially modified during the last two melting seasons particularly because of thermo-erosional effects of a glacial stream which changed at this site from subglacial (until 2015) to glacier-lateral revealing a several tens of meters high unstable ice cliff prone to ice falls of different magnitudes. The second study area is located at the proglacial area. At Pasterze Glacier the proglacial area is widely influenced by dead-ice bodies of various dimensions making this area prone to slow to sudden geomorphic changes caused by ice mass changes. A particular ice-mass movement event took place on 20.09.2016. Within less than one hour the surface of the proglacial area changed substantially by tilting, lateral shifting, and subsidence of the ground accompanied by complete ice disintegration of once-debris covered ice. To understand acting processes at both areas of interest and to quantify mass changes we used field observations, terrain

  4. Does rapid climate change affect sedimentation in a fluvial system? Documenting the PETM using pedogenic carbonate in the Wasatch Formation of Western Colorado

    Science.gov (United States)

    Blecha, A. M.; Gardner, M. H.

    2004-12-01

    . A sequence of minor channelized sandstones follow, interbedded with purple and grey mudstones. These mudstones do not contain carbonate, indicating a return to the previous poorly drained conditions. Carbonate nodules have been collected through the red beds in the western reaches of the outcrop belt. Sampling was at a 0.5 to 8 m resolution, with an average of 2 meters throughout the section. These nodules are currently being analyzed for carbon isotopes to attempt to determine if the negative \\delta 13C shift indicative of the PETM in other basins can be detected in this formation. Assuming the PETM occurs within the red bed interval, lateral tracing to the basin axis correlates these strata to the thick (100 meter) fluvial sandstones of the Molina Member. Whereas the red mudstones along the basin margin indicate drying conditions, the contemporaneous aggradational fluvial system in the basin axis suggests an increase in discharge. This conundrum may reflect the limitations of one dimensional analysis when evaluating the signature of climate in landform evolution.

  5. Towards a sediment budget estimation of the Gepatschferner glacier (Tyrol, Austria) - Approaches and first results

    Science.gov (United States)

    Faust, Matthias; Baewert, Henning; Morche, David

    2015-04-01

    Sediment production, storage and transport in glacial systems are spatially and temporally variable. Due to the ongoing global warming an accelerated glacial retreat is expected, leading to an exposure of unconsolidated sediments. Additionally, a higher sediment production from destabilised rock walls caused by permafrost degradation and glacial debuttressing is expected. At least those paraglacial processes become more important in alpine catchments in the near future. But, there is still a knowledge gap on the quantification of sediment transporting processes in those regions. The research questions we are focussing on are part of the PROSA project ("High-resolution measurements of morphodynamics in rapidly changing Proglacial Systems of the Alps") and are investigated at the Gepatschferner glacier. The Gepatschferner is located in the Eastern European Alps at the south end of the Kaunertal valley. It is the second largest glacier in Austria (15.7 km², 2012). The Gepatschferner is drained by the Fagge River. In this presentation we will focus on two main components of the sediment budget of the Gepatschferner: the input to and the output from the glacier system. The sediment input from the surrounding rockwalls to the glacier is observed by comparing multi-temporal airborne LiDAR DEMs (2006, July 2012, September 2012) to determine sediment delivery by rockfall. In 2012 a gauging station was installed at the Fagge River in front of the glacier outlet in oreder to determine the glacio-fluvial output of sediment from the glacier system. During the ablation periods from 2012 to 2014 the water level was recorded. At different stages the discharge was measured and a reliable stage-discharge relation could be established. That relation was used in combination with the recorded stage for the computation of the hydrograph in each season. Additionally, the solid sediment output was estimated using the discharge data as well as suspended sediment concentration from several

  6. 3D Reconstruction of a Fluvial Sediment Slug from Source to Sink: reach-scale modeling of the Dart River, NZ

    Science.gov (United States)

    Brasington, J.; Cook, S.; Cox, S.; James, J.; Lehane, N.; McColl, S. T.; Quincey, D. J.; Williams, R. D.

    2014-12-01

    Following heavy rainfall on 4/1/14, a debris flow at Slip Stream (44.59 S 168.34 E) introduced >106 m3 of sediment to the Dart River valley floor in NZ Southern Alps. Runout over an existing fan dammed the Dart River causing a sudden drop in discharge downstream. This broad dam was breached quickly; however the temporary loss of conveyance impounded a 3 km lake with a volume of 6 x 106 m3 and depths that exceed 10 m. Quantifying the impact of this large sediment pulse on the Dart River is urgently needed to assess potential sedimentation downstream and will also provide an ideal vehicle to test theories of bed wave migration in large, extensively braided rivers. Recent advances in geomatics offer the opportunity to study these impacts directly through the production of high-resolution DEMs. These 3D snapshots can then be compared through time to quantify the morphodynamic response of the channel as it adjusts to the change in sediment supply. In this study we describe the methods and results of a novel survey strategy designed to capture of the complex morphology of the Dart River along a remote 40 km reach, from the upstream landslide source to its distal sediment sink in Lake Wakatipu. The scale of this system presents major logistical and methodological challenges, and hitherto would have conventionally be addressed with airborne laser scanning, bringing with it significant deployment constraints and costs. By contrast, we present sub-metre 3D reconstructions of the system (Figure 1), derived from highly redundant aerial photography shot with a non-metric camera from a helicopter survey that extended over an 80 km2 area. Structure-from-Motion photogrammetry was used to solve simultaneously camera position, pose and derive a 3D point cloud based on over 4000 images. Reconstructions were found to exhibit significant systematic error resulting from the implicit estimation of the internal camera orientation parameters, and we show how these effects can be minimized

  7. Constraining Subsurface Structure and Composition Using Seismic Refraction Surveys of Proglacial Valleys in the Cordillera Blanca, Peru

    Science.gov (United States)

    Glas, R. L.; Lautz, L.; McKenzie, J. M.; Mark, B. G.; Baker, E. A.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.

    2015-12-01

    As tropical glaciers rapidly recede in response to climate change, the storage and discharge of groundwater will play an increasing role in regulating river baseflow, particularly during the dry season, when stream flow is currently sustained predominantly by glacial melt. Little is understood regarding the hydrogeologic processes controlling base flow characteristics of low-gradient proglacial valleys of the Cordillera Blanca in Northwestern Peru, which has the world's highest density of tropical glaciers. To better understand the processes of groundwater storage and discharge in proglacial meadows, we completed seismic refraction surveys in three representative valleys of the Cordillera Blanca range: the Quilcayhuanca, Yanamarey, and Pachacoto valleys. The locations of survey transects were chosen based on locations of previous sediment core sampling, GPR lines, and quantification of groundwater-surface water interaction derived from dye and temperature tracing experiments. The seismic surveys consisted of 48 vertical component geophones with 2.5 m spacing. Across the three representative valleys a total of 15 surveys were conducted, covering a distance of 1800 m in cross, down, and oblique-valley directions. Preliminary interpretation of the seismic refraction data indicates a maximum imaging depth of 16 m below land surface, and a transition from glacio-lacustrine sediments to buried saturated talus at a depth of 6 m in the Quilcayhuanca valley. The organic-rich glacio-lacustrine sediments in the Yanamarey valley have seismic velocities ranging from 300 to 800 m/s and are >16 m in thickness at mid- valley. Weathered metasedimentary bedrock in the Pachacoto valley was imaged at ~5 m below the valley surface, exhibiting a p-wave velocity of 3400 m/s. The knowledge of hydrogeologic structure derived from seismic refraction surveys will provide crucial boundary conditions for future groundwater models of the valleys of the Cordillera Blanca.

  8. Fluvial geomorphology on Earth-like planetary surfaces: A review.

    Science.gov (United States)

    Baker, Victor R; Hamilton, Christopher W; Burr, Devon M; Gulick, Virginia C; Komatsu, Goro; Luo, Wei; Rice, James W; Rodriguez, J A P

    2015-09-15

    Morphological evidence for ancient channelized flows (fluvial and fluvial-like landforms) exists on the surfaces of all of the inner planets and on some of the satellites of the Solar System. In some cases, the relevant fluid flows are related to a planetary evolution that involves the global cycling of a volatile component (water for Earth and Mars; methane for Saturn's moon Titan). In other cases, as on Mercury, Venus, Earth's moon, and Jupiter's moon Io, the flows were of highly fluid lava. The discovery, in 1972, of what are now known to be fluvial channels and valleys on Mars sparked a major controversy over the role of water in shaping the surface of that planet. The recognition of the fluvial character of these features has opened unresolved fundamental questions about the geological history of water on Mars, including the presence of an ancient ocean and the operation of a hydrological cycle during the earliest phases of planetary history. Other fundamental questions posed by fluvial and fluvial-like features on planetary bodies include the possible erosive action of large-scale outpourings of very fluid lavas, such as those that may have produced the remarkable canali forms on Venus; the ability of exotic fluids, such as methane, to create fluvial-like landforms, as observed on Saturn's moon, Titan; and the nature of sedimentation and erosion under different conditions of planetary surface gravity. Planetary fluvial geomorphology also illustrates fundamental epistemological and methodological issues, including the role of analogy in geomorphological/geological inquiry.

  9. Preface to anthropogenic fluvial sedimentation: Centennial celebration of G.K. Gilbert's Hydraulic-Mining Débris in the Sierra Nevada

    Science.gov (United States)

    James, L. Allan; Phillips, Jonathan D.; Lecce, Scott A.

    2017-10-01

    This special issue celebrates the centennial of the publication of G.K. Gilbert's (1917) monograph, Hydraulic-Mining Débris in the Sierra Nevada, U.S. Geological Survey Professional Paper 105 (PP105). Reasons to celebrate PP105 are manifold. It was the last of four classic monographs that Gilbert wrote in a career that spanned five decades. The monograph, PP105, introduced several important concepts and provided an integrated view of watersheds that was uncommon in its day. It also provided an extreme, lucid example of anthropogenic changes and legacy sediment and how to approach such large-scale phenomena from an objective, quantitative basis.

  10. Temperature signal in suspended sediment export from an Alpine catchment

    Directory of Open Access Journals (Sweden)

    A. Costa

    2018-01-01

    Full Text Available Suspended sediment export from large Alpine catchments ( >  1000 km2 over decadal timescales is sensitive to a number of factors, including long-term variations in climate, the activation–deactivation of different sediment sources (proglacial areas, hillslopes, etc., transport through the fluvial system, and potential anthropogenic impacts on the sediment flux (e.g. through impoundments and flow regulation. Here, we report on a marked increase in suspended sediment concentrations observed near the outlet of the upper Rhône River Basin in the mid-1980s. This increase coincides with a statistically significant step-like increase in basin-wide mean air temperature. We explore the possible explanations of the suspended sediment rise in terms of changes in water discharge (transport capacity, and the activation of different potential sources of fine sediment (sediment supply in the catchment by hydroclimatic forcing. Time series of precipitation and temperature-driven snowmelt, snow cover, and ice melt simulated with a spatially distributed degree-day model, together with erosive rainfall on snow-free surfaces, are tested to explore possible reasons for the rise in suspended sediment concentration. We show that the abrupt change in air temperature reduced snow cover and the contribution of snowmelt, and enhanced ice melt. The results of statistical tests show that the onset of increased ice melt was likely to play a dominant role in the suspended sediment concentration rise in the mid-1980s. Temperature-driven enhanced melting of glaciers, which cover about 10 % of the catchment surface, can increase suspended sediment yields through an increased contribution of sediment-rich glacial meltwater, increased sediment availability due to glacier recession, and increased runoff from sediment-rich proglacial areas. The reduced extent and duration of snow cover in the catchment are also potential contributors to the rise in suspended sediment

  11. Climatic control on extreme sediment transfer from Dokriani Glacier ...

    Indian Academy of Sciences (India)

    The heavy sediment load from the glaciers affects the hydropower generation, irrigation and drinking water supply. Therefore, to understand the sediment delivery from glaciated basins, characteristics and variation of the suspended sediment concentrations in the proglacial meltwater stream, Dokriani Glacier, have been ...

  12. Formation and Demise of an Icing-Dammed Proglacial Lake on Bylot Island, Nunavut, Canada

    Science.gov (United States)

    Blade, M. K.; Moorman, B.

    2016-12-01

    In Sirmilik National Park on Bylot Island, Nunavut, Canada, an icing forms each winter at the terminus of Fountain Glacier. The icing is most likely fed by a spring that discharges year-round through an unfrozen talik within the proglacial permafrost. In the summer, portions of the icing melt as a result of increased solar radiation, warm air temperatures, and an influx of meltwater. In the winter, a proglacial lake often forms dammed by the upvalley glacier, underlying permafrost, and downvalley icing. The objectives of this project were to: 1) characterize water flow through the proglacial area; 2) measure degradation of the icing through July 2014 and its impact on the lake; and 3) infer the 2014 proglacial lake formation history. The methods employed were DGPS mapping of the surficial ice and lake bathymetry, time-lapse photography of the hydrological activity, and dye tracing to identify hydrological connectivity. Results indicate that: 1) water flowed into, out of, and through the proglacial lake area through pathways established during the lake area formation. Water sources feeding the lake include: a spring, supra-glacial runoff, subglacial discharge, lateral stream, terrestrial stream, and meltwater from floating lake ice. 2) Icing degradation was most rapid at the marginal stream contact with running water resulting in a 0.8 metre lowering of lake water level. 3) The proglacial lake formed due to persistence of unfrozen water upvalley of the icing from the groundwater spring continuous water supply.

  13. Understanding Sediment Sources, Pathways, and Sinks in Regional Sediment Management: Application of Wash Load and Bed-Material Load Concept

    National Research Council Canada - National Science Library

    Biedenham, David S; Hubbard, Lisa C; Thome, Colin R; Watson, Chester C

    2006-01-01

    ... through the fluvial system for sediments derived from various bed, bank, gully, and catchment sources thereby providing a reliable analytical foundation for effective regional sediment management...

  14. Rivers through geological time : the fluvial contribution to understanding of our planet.

    OpenAIRE

    Bridgland, D.R.; Bennett, J.A.; McVicar-Wright, S.E.; Scrivener, R.C.

    2014-01-01

    Fluvial rocks and sediments form an important part of the geological record from the terrestrial environment, from the Archaean to the recent. Precambrian fluvial archives record the change in Earth's atmosphere from anoxic to oxygen-rich, while the absence of land plants led to significant differences between Precambrian and Palaeozoic fluvial regimes and those from later in the geological record. In the Mesozoic and Cenozoic river valleys were populated by land animals and their deposits ar...

  15. The Fluvial Information System

    Science.gov (United States)

    Dugdale, S. J.; Carbonneau, P.; Clough, S.

    2009-12-01

    River ecologists have long been aware that our understanding of lotic ecology is limited by our lack of methods applicable to catchment scale processes. Furthermore, the EU’s Water Framework Directive states that surface waters must be managed at catchment scales. This has created a need for a new approach to high-resolution catchment scale data collection in fluvial environments. In response to this, remote sensing has been the focus of increasing interest in river science, and it is now possible to map parameters such as water depth, grain size and habitat type with sub-metric resolutions over large areas. These techniques are capable of yielding unprecedented amounts of information about river systems, and with such levels of information, crucial questions about catchment scale ecology can now be addressed. However, this intensive approach produces vast amounts of raster data leading to significant issues in terms of data management, and extracting spatially explicit information from large image databases poses a significant challenge which must be resolved if fluvial remote sensing methods are to deliver their potential. GIS has already been successfully applied to manage remotely sensed data. Unfortunately, when applied to fluvial remote sensing raster data, traditional GIS appears limited and unsuited to the specific tasks required by river scientists and managers, and experience with GIS packages has shown that they become overwhelmed when faced with datasets comprising thousands of rasters. Another fundamental issue with traditional GIS packages is the use of established Cartesian map projection systems. Given that rivers are curvilinear entities, the use of Cartesian grid map projections is mismatched and curvilinear coordinate systems unique to each river will be required. This paper introduces the Fluvial Information System (FIS), a raster based GIS-type system designed to manage fluvial remote sensing data and automatically extract meaningful

  16. Variability in fluvial geomorphic response to anthropogenic disturbance

    Science.gov (United States)

    Verstraeten, Gert; Broothaerts, Nils; Van Loo, Maarten; Notebaert, Bastiaan; D'Haen, Koen; Dusar, Bert; De Brue, Hanne

    2017-10-01

    Humans have greatly impacted the processes and intensities of erosion, sediment transport and storage since the introduction of agriculture. In many regions around the world, accelerated floodplain sedimentation can be related to increases in human pressure on the environment. However, the relation between the intensity of anthropogenic disturbance and the magnitude of change in fluvial sediment dynamics is not straightforward and often non-linear. Here, we review a number of case studies from contrasting environmental settings in the European loess belt, the Eastern Mediterranean mountain ranges and the eastern USA. Detailed field-based sediment archive studies and sediment budgets covering time periods ranging from 200 to over 5000 year, as well as the use of pollen and sediment provenance techniques, show that no overarching concept of changes in floodplain sedimentation following anthropogenic disturbance can be established. Slope-channel (dis)connectivity controls the existence of thresholds or tipping points that need to be crossed before significant changes in downstream sediment dynamics are recorded following human impact. This coupling can be related to characteristics of human pressure such as its duration, intensity and spatial patterns, but also to the geomorphic and tectonic setting. Furthermore, internal feedback mechanisms, such as those between erosion and soil thickness, further complicate the story. All these factors controlling the propagation of sediment from eroding hillslopes to river channels vary between regions. Hence, only unique patterns of fluvial geomorphic response can be identified. As a result, unravelling the human impact from current-day sediment archives and predicting the impact of future human disturbances on fluvial sediment dynamics remain a major challenge. This has important implications for interpreting contemporary sediment yields as well as downstream sediment records in large floodplains, deltas and the marine

  17. Origin and Distribution of Methane Entrapped in Calcareous Alpine Proglacial Soil

    Science.gov (United States)

    Zhu, Biqing; Schroth, Martin H.; Henneberger, Ruth; Kübler, Manuel; Zeyer, Josef

    2017-04-01

    Methane (CH4) is an important greenhouse gas. The atmospheric methane concentration has been increasing in recent years, which is caused by imbalance between sources and sinks. Methane has been recently discovered to be entrapped in calcareous Swiss Alpine proglacial soil. This CH4 can be released upon mechanical impact and acidification. However, the amount, distribution and environmental fate of this entrapped CH4 in proglacial environment remain unknown. The entrapped CH4 in proglacial soil may be of modern or ancient origin. Modern origin includes ongoing or recent microbial CH4 production (methanogenesis) in subglacial or proglacial environments. An ancient origin mainly refers to CH4 produced thermogenically. This soil entrapped CH4 might be a common phenomenon along the entire glacial forefield, or it might only be present at few locations and depth. We present results of studies from two Swiss Alpine Glacier catchments, Wildstrubel Glacier (Canton Valais) and the Griessfirn Glacier (Canton Uri). Our main goals were 1) to assess the origin of CH4 entrapped in various glacial environments (subglacial, proglacial and supraglacial, soil and bedrocks) using geochemical and microbiological evidence; 2) to assess the spatial distribution of entrapped CH4. We performed geochemical analysis (CH4 content, gas wetness ([C1]/[C2-C3] alkane ratio), CH4 stable 13C- and 2H-isotopes, TOC) on subglacial, proglacial, and supraglacial soil samples collected from well-aerated and water-logged locations. Geochemical analysis was also selectively conducted on pore-water samples and on rock samples collected from different geological formations along the catchments. We also performed batch incubations on soil samples collected from subglacial, proglacial water-logged and supraglacial zones. In addition, for the aforementioned three types of samples, we also performed molecular analyses targeting the mcrA gene, which encodes the α-subunit of the enzyme methyl-coenzyme M reductase

  18. A late Holocene pollen record from proglacial Oblong Tarn, Mount Kenya.

    Directory of Open Access Journals (Sweden)

    Colin J Courtney Mustaphi

    -elevation temperature reconstruction, which supported the strong influence of uphill pollen transport from montane forest vegetation and association between temperatures and montane vegetation dynamics. Pollen accumulation rates showed some variability related to minerogenic sediment input to the lake. The Oblong Tarn pollen record provides an indication of long term vegetation change atop Mount Kenya showing some decreases in local alpine and ericaceous taxa from 5300-3100 cal yr BP and minor centennial-scale variability of montane taxa from mid elevation forests. The record highlights potentials, challenges and opportunities for the use of proglacial lacustrine sediment to examine vegetation change on prominent mountain massifs.

  19. A late Holocene pollen record from proglacial Oblong Tarn, Mount Kenya.

    Science.gov (United States)

    Courtney Mustaphi, Colin J; Gajewski, Konrad; Marchant, Rob; Rosqvist, Gunhild

    2017-01-01

    reconstruction, which supported the strong influence of uphill pollen transport from montane forest vegetation and association between temperatures and montane vegetation dynamics. Pollen accumulation rates showed some variability related to minerogenic sediment input to the lake. The Oblong Tarn pollen record provides an indication of long term vegetation change atop Mount Kenya showing some decreases in local alpine and ericaceous taxa from 5300-3100 cal yr BP and minor centennial-scale variability of montane taxa from mid elevation forests. The record highlights potentials, challenges and opportunities for the use of proglacial lacustrine sediment to examine vegetation change on prominent mountain massifs.

  20. Fluvial experiments using inertial sensors.

    Science.gov (United States)

    Maniatis, Georgios; Valyrakis, Manousos; Hodge, Rebecca; Drysdale, Tim; Hoey, Trevor

    2017-04-01

    During the last four years we have announced results on the development of a smart pebble that is constructed and calibrated specifically for capturing the dynamics of coarse sediment motion in river beds, at a grain scale. In this presentation we report details of our experimental validation across a range of flow regimes. The smart pebble contains Inertial Measurements Units (IMUs), which are sensors capable of recording the inertial acceleration and the angular velocity of the rigid bodies into which they are attached. IMUs are available across a range of performance levels, with commensurate increase in size, cost and performance as one progresses from integrated-circuit devices for use in commercial applications such as gaming and mobile phones, to larger brick-sized systems sometimes found in industrial applications such as vibration monitoring and quality control, or even the rack-mount equipment used in some aerospace and navigation applications (which can go as far as to include lasers and optical components). In parallel with developments in commercial and industrial settings, geomorphologists started recently to explore means of deploying IMUs in smart pebbles. The less-expensive, chip-scale IMUs have been shown to have adequate performance for this application, as well as offering a sufficiently compact form-factor. Four prototype sensors have been developed so far, and the latest (400 g acceleration range, 50-200 Hz sampling frequency) has been tested in fluvial laboratory experiments. We present results from three different experimental regimes designed for the evaluation of this sensor: a) an entrainment threshold experiment ; b) a bed impact experiment ; and c) a rolling experiment. All experiments used a 100 mm spherical sensor, and set a) were repeated using an equivalent size elliptical sensor. The experiments were conducted in the fluvial laboratory of the University of Glasgow (0.9 m wide flume) under different hydraulic conditions. The use of

  1. Fluvial geomorphology on Earth-like planetary surfaces: A review

    Science.gov (United States)

    Baker, Victor R.; Hamilton, Christopher W.; Burr, Devon M.; Gulick, Virginia C.; Komatsu, Goro; Luo, Wei; Rice, James W.; Rodriguez, J.A.P.

    2017-01-01

    Morphological evidence for ancient channelized flows (fluvial and fluvial-like landforms) exists on the surfaces of all of the inner planets and on some of the satellites of the Solar System. In some cases, the relevant fluid flows are related to a planetary evolution that involves the global cycling of a volatile component (water for Earth and Mars; methane for Saturn’s moon Titan). In other cases, as on Mercury, Venus, Earth’s moon, and Jupiter’s moon Io, the flows were of highly fluid lava. The discovery, in 1972, of what are now known to be fluvial channels and valleys on Mars sparked a major controversy over the role of water in shaping the surface of that planet. The recognition of the fluvial character of these features has opened unresolved fundamental questions about the geological history of water on Mars, including the presence of an ancient ocean and the operation of a hydrological cycle during the earliest phases of planetary history. Other fundamental questions posed by fluvial and fluvial-like features on planetary bodies include the possible erosive action of large-scale outpourings of very fluid lavas, such as those that may have produced the remarkable canali forms on Venus; the ability of exotic fluids, such as methane, to create fluvial-like landforms, as observed on Saturn’s moon, Titan; and the nature of sedimentation and erosion under different conditions of planetary surface gravity. Planetary fluvial geomorphology also illustrates fundamental epistemological and methodological issues, including the role of analogy in geomorphological/geological inquiry. PMID:29176917

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

    Science.gov (United States)

    Turner, Jonathan; Macklin, Mark; Jones, Anna

    2010-05-01

    Holocene flooding episodes. In addition, this investigation reveals systematically lower sedimentation rates across Ireland compared to the UK, which may have reduced the geomorphic effectiveness of fluvial sediment archives to record major flood events. These considerations, together with an increasing focus on regional variations in fluvial activity across the Holocene, can only be properly addressed with a more concerted and expanded programme of Holocene fluvial research in Ireland.

  3. Contemporary suspended sediment dynamics within two partly glacierized mountain drainage basins in western Norway (Erdalen and Bødalen, inner Nordfjord)

    Science.gov (United States)

    Beylich, Achim A.; Laute, Katja; Storms, Joep E. A.

    2017-06-01

    the drainage basin surface area) as compared to Erdalen (18% of the drainage basin surface area) and by a significantly higher sediment yield from the glacierized area of the Bødalen drainage basin compared to the glacierized surface area in Erdalen. When looking at the total annual mass of suspended sediments being fluvially exported from both entire drainage basin systems, the total amount of suspended sediments coming from the ice-free drainage basin surface areas altogether dominates over the total amount of suspended sediments coming from the glacierized surface area of both drainage basins. Drainage-basin wide annual suspended sediment yields are rather low when compared with yields of other partly glacierized drainage basin systems in Norway and in other cold climate environments worldwide, which is mainly due to the high resistance of the predominant gneisses towards glacial erosion and weathering, the altogether only small amounts of sediments being available within the entire drainage basin systems, the stable and nearly closed vegetation cover in the ice-free surface areas with sedimentary covers, and the efficiency of proglacial lakes in trapping sediments supplied by defined outlet glaciers. Both contemporary and long-term suspended sediment yields are altogether supply-limited. Contemporary suspended sediment transport accounts for nearly two-thirds of the total fluvial transport and, accordingly, plays an important role within the sedimentary budgets of the entire Erdalen and Bødalen drainage basins.

  4. Mobile TLS application for fluvial studies

    Science.gov (United States)

    Alho, P.; Kukko, A.; Hyyppä, H.; Kaartinen, H.; Hyyppä, J.; Jaakkola, A.

    2009-04-01

    dense point cloud spatially; making the three-dimensional mapping of sub-centimetre fluvial morphology feasible. The BoMMS approach was an extremely rapid methodology for surveying riverine topography, taking only 85 minutes to survey a reach approximately six kilometres in length. The BoMMS scanning was completed with static terrestrial laser scanning to further increase the density of the entire DTM collected from the point bar. Further, this paper demonstrates the three-dimensional mapping of a point-bar and its detailed morphology. Compared to the BoMMS surface, approximately, 80 % and 96% of the TLS points showed a height deviation of less than 2 cm and 5 cm, respectively, with an overall standard deviation of ± 2.7 cm. This level of accuracy and promptness enables the mapping of post-flood deposition directly after a flood event without an extensive time lag. Additionally, the improved object characterisation allowed for better calculation of the point bar volume, as well as the sediment budget of the river, using multi-temporal data. Due to the rapid development of laser scanning technology, the cost of systems like BoMMS are constantly becoming cheaper, promoting their increased use. More research is needed in the future to verify the full potential of boat-based scanning, combined with TLS and ALS, for fluvial studies. Based on the collected data, automatic algorithms require development, as do those needed for the semi-automatic mapping of the fluvial depositions. Additionally, multi-temporal laser scanning data must be further developed for the calibration and validation data of computational fluid dynamics.

  5. Pro-glacial soil variability and geomorphic activity - the case of three Swiss valleys

    NARCIS (Netherlands)

    Temme, A.J.A.M.; Lange, de K.

    2014-01-01

    Soils in pro-glacial areas are often approached from a chronosequence viewpoint. In the chronosequence approach, the objective is to derive rates of soil formation from differences in properties between soils of different age. For this reason, in chronosequence studies, soils are sampled in

  6. Monitoring of jökulhlaups and element fluxes in proglacial Icelandic rivers using osmotic samplers

    Science.gov (United States)

    Jones, Morgan T.; Gałeczka, Iwona M.; Gkritzalis-Papadopoulos, Athanasios; Palmer, Martin R.; Mowlem, Matthew C.; Vogfjörð, Kristín; Jónsson, Þorsteinn; Gislason, Sigurður R.

    2015-01-01

    The quantification of volatile emissions from volcanoes is an integral part of understanding magmatic systems, with the exsolution and extent of volcanic degassing having a large impact on the nature of an eruption. Measurements of volatiles have traditionally focused on gas emissions into the atmosphere, but volatiles can also become dissolved in proximal water bodies en route to the surface. Thus the monitoring of rivers draining active volcanic areas can provide insights to identifying changes in activity. This process is particularly important for sub-glacial volcanoes in Iceland, where much of the volatile release is transported within glacial outbreak floods, termed jökulhlaups. Monitoring and characterising these phenomena is hampered by the dependence on spot sampling of stochastic events under challenging field conditions, which often leads to bias in the collected data. A recent technological advance is the osmotic sampler, an electricity-free pump that continuously collects water that can subsequently be divided into time-averaged samples. This technique allows for continued and unsupervised deployment of a sampler for weeks to months, representing a cost-efficient form of chemical monitoring. In this study we deployed osmotic samplers in two rivers in southern Iceland. Skálm is a proglacial river from Mýrdalsjökull glacier and Katla volcano, while Skaftá is a larger drainage system from the western part of Vatnajökull glacier. Both rivers are prone to jökulhlaups from geothermal and volcanic sources, and a small jökulhlaup of geothermal origin occurred during the second deployment in Skaftá in January 2014. The two deployments show that osmotic samplers are capable of delivering accurate chemical data in turbulent conditions for several key elements. Total dissolved fluxes for the deployment at Skaftá are calculated to be Na = 9.9 tonnes/day, Mg = 10.5 t/d, Si = 34.7 t/d, Cl = 11.0 t/d, Ca = 31.6 t/d, DIC = 50.8 t/d, and SO4 = 28.3 t/d, with

  7. Hydrologic exchange and chemical weathering in a proglacial watershed near Kangerlussuaq, west Greenland

    Science.gov (United States)

    Deuerling, Kelly M.; Martin, Jonathan B.; Martin, Ellen E.; Scribner, Cecilia A.

    2018-01-01

    The exchange of proglacial river water with active layer pore water could alter water chemical compositions in glacial outwash plains and oceanic solute fluxes. To evaluate effects of this exchange, we sampled Watson River and adjacent pore water during the 2013 melt season at two sandurs in western Greenland; one in Sandflugtdalen and the other near the confluence with Søndre Strømfjord. We measured temperature, specific conductivity, and head gradients between the river and bank over a week-long period at Sandflugtdalen, as well as sediment hydraulic conductivity and chemical compositions of waters from both sites. Specific conductivity of pore water is four to ten times greater than river water as solutes are concentrated from weathering reactions, cryoconcentration, and evaporation. Pore water compositions are predominantly altered by carbonate dissolution and sulfide mineral oxidation. High concentrations of HCO3 and SO4 result from solute recycling and dissolution of secondary Ca-Mg carbonate/sulfate salts initially formed by near-surface evaporation in the summer and at depth by freeze-in of the active layer and cryoconcentration in the winter. High hydraulic conductivity (10-5 to 10-4 m/s) and diurnal fluctuations of river stage during our study caused exchange of river and pore water immediately adjacent to the river channel, with a net loss of river water to the bank. Pore water >6 m from the river continuously flowed away from the river. Approximately 1-8% of the river discharge through the Sandflugtdalen was lost to the river bank during our 6.75 day study based on calculations using Darcy's Law. Although not sampled, some of this water should discharge to the river during low river stage early and late in the melt season. Elevated pore water solute concentrations in sandurs and water exchange at diurnal and seasonal frequency should impact fluxes of solutes to the ocean, although understanding the magnitude of this effect will require long

  8. Sedimentation in a river dominated estuary

    CSIR Research Space (South Africa)

    Cooper, JAG

    1993-10-01

    Full Text Available is restricted to a small flood tidal delta. Sequential aerial photography, sediment sampling and topographical surveys reveal a cyclial pattern of sedimentation that is mediated by severe fluvial floods which exceed normal energy thresholds. During severe floods...

  9. Fluvial landscapes of the Harappan civilization.

    Science.gov (United States)

    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

    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.

  10. Aeolian sedimentation in the middle buntsandstein in the eifel north-south depression zone: Summary of the variability of sedimentary processes in a buntsandstein erg as a base for evaluation of the mutual relationships between aeolian sand seas and fluvial river systems in the mid-european buntsandstein

    Science.gov (United States)

    Mader, Detlef

    The spectrum of aeolian depositional subenvironments in the upper Middle Buntsandstein Karlstal-Schichten sequence in the Eifel North-South-zone at the western margin of the Mid-European Triassic Basin comprises trains of larger and higher narrowly-spaced dunes in sand seas, isolated smaller and lower widely-spaced dunes in floodplains and interdune playas, dry interdune sheet sands, damp interdune adhesive sandflats, wet interdune playa lakes, rainfall runoff watercourses and ephemeral channels cutting through the dune belt, and deflation gravel lag veneers. Distinction of aeolian and fluvial sediments within the succession of closely intertonguing wind- and water-laid deposits is possible by independent analysis of the conventional criteria and the more modern stratification styles. Thick cross-bedded aeolian sand sequences originate as barchanoid-type dunes which accumulate and migrate in the regime of narrow to wide unimodal southeasterly to southwesterly trade winds in low northern palaeolatitude in summer when the intertropical convergence zone is shifted to the north. The predominantly transverse-ridge dunes accrete mainly by grainfall and subcritical climbing of wind ripples, subordinately also by grainflow interfingering with grainfall. Horizontal-laminated aeolian sands form as sand sheets in dry interdune playas by subcritical migration of wind ripple trains, rarely also by plane bed accretion. Thin cross-bedded dune sands or horizontal-laminated aeolian sands capping fluvial cyclothems originate by deflation of emerged alluvial bar sands during low-water stages and subsequent accumulation of the winnowed sand as widely-spaced dunelets or chains of wind ripples in desiccated parts of the adjoining floodplain. The aeolian sand layers at the base of lacustrine cyclothems record migration of isolated little dunes across the dry playa floor at the beginning of a wetting-upwards cyclothem, with the sand deriving from deflation of fluvial incursions or

  11. Fluvial response to environmental perturbations: a perspective from physical experiments

    Science.gov (United States)

    Savi, Sara; Tofelde, Stefanie; Wickert, Andrew; Schildgen, Taylor; Paola, Chris; Strecker, Manfred

    2016-04-01

    Fluvial terraces and alluvial fans that are perched above the modern base level testify to environmental conditions that were different from today. Sedimentological studies combined with chronological constraints can be used to reconstruct the evolution of these landforms in the context of past changes in regional to global forcing. Despite the improvements in the most commonly used dating techniques (e.g. cosmogenic nuclides, 14C, and OSL), field data from fluvial and alluvial archives often represent only a brief glimpse into the evolution of that particular landscape. As such, the challenge of interpreting landscape development and its relationship to external forcing in the remaining time gaps is often unclear. To gain more insight, we performed physical experiments to test how a fluvial system responds to changes in the boundary conditions. This approach allows us to continuously record the evolution of the fluvial system and to observe, step by step, the response of the fluvial system and the development of the landscape. Additionally, we can directly link the geomorphic modifications to a specific environmental perturbation. Starting with a simple model and a single channel, we changed the amount of discharge (Qw) and sediment supply (Qs) in the system. The most prominent response results from a sudden increase in water discharge. In general, changes in the Qs/Qw ratio control the fluvial morphology (particularly the height/width ratio), the channel's profile, the dynamics of the river, and its ability to modify the surrounding landscape. Responses get more complex with the introduction of a lateral tributary, which changes the dynamics of the main stem and creates feed-back mechanisms between the two systems. For example, a change in the main stem can influence the fluvial morphology and the steepness of the tributary (even with no perturbations in the tributary) and vice-versa, illustrating the potential for non-unique interpretations of fluvial landforms

  12. Deconvolving the process-origin of sediments on volcanic mountains and implications for paleoclimatic reconstruction: Mt Ruapehu area, New Zealand

    Science.gov (United States)

    Brook, Martin; Winkler, Stefan

    2016-04-01

    Glaciation on the central North Island of New Zealand is limited to the volcanoes of Tongariro National Park, including Mt Ruapehu, the largest and most active andesitic stratovolcano on the North Island. At 2797 m asl, Mt Ruapehu represents the only peak in the North Island to currently intercept the permanent snowline, with small cirque glaciers descending to an altitude of ~2300 m. During the last glacial maximum (LGM), small ice-caps existed on Mt Ruapehu and the Tongariro Massif (15 km to the NNE of Ruapehu), with a series of small (clast roundness, clast shape and textural characteristics associated with active and former glaciers on Mt Ruaephu and the Tongariro Massif, in order to assist in classifying the process-origin of sediments on glaciated volcanic mountains. Supraglacial inputs include rockfall, tephra, and avalanche material delivered to the surface of glaciers. Basal debris, where observed at the terminus of active cirque glaciers, consists mainly of incorporated fluvial material. Following deposition, reworking is mainly by proglacial streams, debris flows and lahars. Within the vicinity of glaciers, the dominant facies appear to be: (i) bouldery gravel with angular clasts on steep slopes surrounding glaciers, (ii) silty-sandy boulder gravel, with mainly subangular clasts, forming lateral moraines, (iii) boulder/cobble gravel with mainly subrounded clasts and associated laminated sediments representing fluvially-reworked material; and (iv) debris-avalanche deposits including fragmental rock clasts with an unsorted inter-clast matrix. As some of these deposits appear to include unambiguous indicators of glacial transport, interpretation of unconsolidated debris ridges on volcanic mountains should not necessarily exclude the contribution of glacial processes.

  13. A {approx}180,000 years sedimentation history of a perialpine overdeepened glacial trough (Wehntal, N-Switzerland)

    Energy Technology Data Exchange (ETDEWEB)

    Anselmetti, F. S. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf (Switzerland); Drescher-Schneider, R. [Institut fuer Pflanzenwissenschaften, Karl-Fanzen-Universitaet Graz, Graz (Austria); Furrer, H. [Palaeontologisches Institut und Museum, Universitaet Zuerich, Zuerich (Switzerland); Graf, H. R. [Matousek, Baumann und Niggli AG, Baden (Switzerland); Lowick, S. E.; Preusser, F. [Institut fuer Geologie, Universitaet Bern, Bern (Switzerland); Riedi, M. A. [Marc A. Riedi, Susenbuehlstrasse 41, Chur (Switzerland)

    2010-11-15

    A 30 m-deep drill core from a glacially overdeepened trough in Northern Switzerland recovered a {approx} 180 ka old sedimentary succession that provides new insights into the timing and nature of erosion-sedimentation processes in the Swiss lowlands. The luminescence-dated stratigraphic succession starts at the bottom of the core with laminated carbonate-rich lake sediments reflecting deposition in a proglacial lake between {approx} 180 and 130 ka ago (Marine Isotope Stage MIS 6). Anomalies in geotechnical properties and the occurrence of deformation structures suggest temporary ice contact around 140 ka. Up-core, organic content increases in the lake deposits indicating a warming of climate. These sediments are overlain by a peat deposit characterised by pollen assemblages typical of the late Eemian (MIS 5e). An abrupt transition following this interglacial encompasses a likely hiatus and probably marks a sudden lowering of the water level. The peat unit is overlain by deposits of a cold unproductive lake dated to late MIS 5 and MIS 4, which do not show any direct influence from glaciers. An upper peat unit, the so-called {sup M}ammoth peat{sup ,} previously encountered in construction pits, interrupts this cold lacustrine phase and marks more temperate climatic conditions between 60 and 45 ka (MIS 3). In the upper part of the core, a succession of fluvial and alluvial deposits documents the Late Glacial and Holocene sedimentation in the basin. The sedimentary succession at Wehntal confirms that the glaciation during MIS 6 did not apparently cause the overdeepening of the valley, as the lacustrine basin fill covering most of MIS 6 is still preserved. Consequently, erosion of the basin is most likely linked to an older glaciation. This study shows that new dating techniques combined with paleoenvironmental interpretations of sediments from such overdeepened troughs provide valuable insights into the past glacial history. (authors)

  14. Monitoring the Dynamic of a Fluvial Channel after Lahar Disturbance: Huiloac Gorge (Popocatepetl Volcano, Mexico)

    Science.gov (United States)

    Andres, N.; Palacios, D.; Zamorano, J. J.; Tanarro, L. M.; Renschler, C.; Sanjosé, J. J.; Atkinson, A.

    2009-04-01

    Capra, L.; Poblete, M.A. and Alvarado, R. 2004. The 1997 and 2001 lahars of Popocatépetl volcano (Central Mexico): textural and sedimentological constraints on their origin and hazards. Journal of Volcanology and Geothermal Research, 131: 351-369. Gran, K. y Montgomery, D., 2005. Spatial and temporal patterns in fluvial recovery following volcanic eruptions: Channel response to basin-wide sediment loading at Mount Pinatubo, Philippines. GSA Bulletin, 117; 1-2: 195-211. Hayes, S.K., Montgomery, D.R. and Newhall, C.G., 2002, Fluvial sediment transport and deposition following the 1991 eruption of Mt. Pinatubo. Geomorphology. Vol. 45: 211-224. Major, J.J., Pierson, T.C., Dinehart, R.L. y Costa, J.E. 2000. Sediment yield following severe volcanic disturbance- A two-decade perspective from Mount St. Helens. Geology, 28, n° 9: 819-822. Major, J.J., 2003. Post-eruption hydrology and sediment transport in volcanic river systems, Water Resources IMPACT, 5(3): 10-15. Muñoz, E. 2007. Los lahares del Popocatépetl: tratamiento de la información para la prevención de catástrofes. (PhD thesis, Universidad Complutense de Madrid.) Palacios, D., 1995. Rockslide processes on the north slope of Popocatépetl Volcano, Mexico, Permafrost and Periglaciar Processes, 6: 345-356. Palacios, D., J.J. Zamorano and G. Parrilla. 1998. Proglacial debris flows in Popocatépetl North Face and their relation to 1995 eruption. Z. Geomorph. N. P., 42(3), 273-295 Palacios, D., J.J. Zamorano and A. Gómez. 2001. The impact of present lahars on the geomorphologic evolution of proglacial gorges: Popocatépetl, Mexico. Geomorphology, 37(1-2), 15-42.

  15. Landform Evolution Modeling of Specific Fluvially Eroded Physiographic Units on Titan

    Science.gov (United States)

    Moore, J. M.; Howard, A. D.; Schenk, P. M.

    2015-01-01

    Several recent studies have proposed certain terrain types (i.e., physiographic units) on Titan thought to be formed by fluvial processes acting on local uplands of bedrock or in some cases sediment. We have earlier used our landform evolution models to make general comparisons between Titan and other ice world landscapes (principally those of the Galilean satellites) that we have modeled the action of fluvial processes. Here we give examples of specific landscapes that, subsequent to modeled fluvial work acting on the surfaces, produce landscapes which resemble mapped terrain types on Titan.

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

    Science.gov (United States)

    Gray, Harrison J.; Mahan, Shannon

    2015-01-01

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

  17. Isochron of Holocene fluvial and estuarine (Qfe) sediment thickness beneath the Massachusetts inner continental shelf between Nahant and Northern Cape Cod Bay (qfeiso Esri binary grid; UTM, Zone 19N, WGS 84)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data are qualitatively derived interpretive polygon shapefiles and selected source raster data defining surficial geology, sediment type and distribution, and...

  18. Isopach of Holocene fluvial and estuarine (Qfe), nearshore marine (Qmn), and deepwater marine (Qmd) sediment thickness beneath Vineyard and western Nantucket Sounds, Massachusetts (Esri binary grid; UTM, Zone 19N, WGS 84)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Geologic, sediment texture, and physiographic zone maps characterize the sea floor of Vineyard and western Nantucket Sounds, Massachusetts. These maps were derived...

  19. How quickly do High Arctic coastal environments respond to rapid deglaciation and the paraglacial transformation of proglacial areas? - Answers from Spitsbergen, Svalbard Archipelago

    Science.gov (United States)

    Strzelecki, Matt; Long, Antony; Lloyd, Jerry; Zagórski, Piotr

    2014-05-01

    The coastal zone is one of the most important storage systems for sediments that are eroded and transported by rivers, wind and slope processes from deglacierised valleys and proglacial areas before reaching their final sediment sink (fjords or the open sea. The Svalbard archipelago provides an excellent location to quantify how High Arctic coasts are responding to climate warming and the associated paraglacial landscape transformations. In this paper we summarize the results of several coastal surveys carried out by our research teams along the paraglacial coasts of Spitsbergen during the last decade. We reconstruct the post-Little Ice Age development of selected coastlines in Spitsbergen to illustrate the variable coastal response to paraglacial and periglacial processes activated following the recent retreat of glaciers. Our surveys use aerial photogrammetric and GIS analyses, sedimentological classification of coastal deposits and field-based geomorphological mapping in Kongsfjorden, Billefjorden, Bellsund, Hornsund and Sørkappland. Our results document dramatic changes in sediment flux and coastal response under intervals characterized by a warming climate, retreating local ice masses, a shortened winter sea-ice season and thawing permafrost. The study highlights the need for a greater understanding of the controls on High Arctic coastal geomorphology, especially given the potential for future accelerated warming and sea-level rise.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-01

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

  1. Fluvial valleys and Martian palaeoclimates

    Science.gov (United States)

    Gulick, Virginia C.; Baker, Victor R.

    1989-10-01

    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.

  2. Lacustrine-fluvial interactions in Australia's Riverine Plains

    Science.gov (United States)

    Kemp, Justine; Pietsch, Timothy; Gontz, Allen; Olley, Jon

    2017-06-01

    Climatic forcing of fluvial systems has been a pre-occupation of geomorphological studies in Australia since the 1940s. In the Riverine Plain, southeastern Australia, the stable tectonic setting and absence of glaciation have combined to produce sediment loads that are amongst the lowest in the world. Surficial sediments and landforms exceed 140,000 yr in age, and geomorphological change recorded in the fluvial, fluvio-lacustrine and aeolian features have provided a well-studied record of Quaternary environmental change over the last glacial cycle. The region includes the Willandra Lakes, whose distinctive lunette lakes preserve a history of water-level variations and ecological change that is the cornerstone of Australian Quaternary chronostratigraphy. The lunette sediments also contain an ancient record of human occupation that includes the earliest human fossils yet found on the Australian continent. To date, the lake-level and palaeochannel records in the Lachlan-Willandra system have not been fully integrated, making it difficult to establish the regional significance of hydrological change. Here, we compare the Willandra Lakes environmental record with the morphology and location of fluvial systems in the lower Lachlan. An ancient channel belt of the Lachlan, Willandra Creek, acted as the main feeder channel to Willandra Lakes before channel avulsion caused the lakes to dry out in the late Pleistocene. Electromagnetic surveys, geomorphological and sedimentary evidence are used to reconstruct the evolution of the first new channel belt following the avulsion. Single grain optical dating of floodplain sediments indicates that sedimentation in the new Middle Billabong Palaeochannel had commenced before 18.4 ± 1.1 ka. A second avulsion shifted its upper reaches to the location of the present Lachlan River by 16.2 ± 0.9 ka. The timing of these events is consistent with palaeohydrological records reconstructed from Willandra Lakes and with the record of

  3. The effects of land use on fluvial sediment chemistry for the conterminous U.S. - Results from the first cycle of the NAWQA Program: Trace and major elements, phosphorus, carbon, and sulfur

    Science.gov (United States)

    Horowitz, A.J.; Stephens, V.C.

    2008-01-01

    In 1991, the U.S. Geological Survey (USGS) began the first cycle of its National Water Quality Assessment (NAWQA) Program. The Program encompassed 51 river basins that collectively accounted for more than 70% of the total water use (excluding power generation), and 50% of the drinking water supply in the U.S. The basins represented a variety of hydrologic settings, rock types (geology), land-use categories, and population densities. One aspect of the first cycle included bed sediment sampling; sites were chosen to represent baseline and important land-use categories (e.g., agriculture, urban) in each basin. In total, over 1200 bed sediment samples were collected. All samples were size-limited (< 63????m) to facilitate spatial and/or temporal comparisons, and subsequently analyzed for a variety of chemical constituents including major (e.g., Fe, Al,) and trace elements (e.g., Cu, Zn, Cd), nutrients (e.g., P), and carbon. The analyses yielded total (??? 95% of the concentrations present), rather than total-recoverable chemical data. Land-use percentages, upstream underlying geology, and population density were determined for each site and evaluated to asses their relative influence on sediment chemistry. Baseline concentrations for the entire U.S. also were generated from a subset of all the samples, and are based on material collected from low population (??? 27??p km- 2) density, low percent urban (??? 5%), agricultural or undeveloped areas. The NAWQA baseline values are similar to those found in other national and global datasets. Further, it appears that upstream/underlying rock type has only a limited effect (mostly major elements) on sediment chemistry. The only land-use category that appears to substantially affect sediment chemistry is percent urban, and this result is mirrored by population density; in fact, the latter appears more consistent than the former.

  4. Individual and cumulative effects of agriculture, forestry and metal mining activities on the metal and phosphorus content of fluvial fine-grained sediment; Quesnel River Basin, British Columbia, Canada.

    Science.gov (United States)

    Smith, Tyler B; Owens, Philip N

    2014-10-15

    The impact of agriculture, forestry and metal mining on the quality of fine-grained sediment (forestry and mining activities in the basin (i.e. "impacted" sites). Samples were also collected from replicate reference sites and also from the main stem of the Quesnel River at the downstream confluence with the Fraser River. Generally, metal(loid) and phosphorus (P) concentrations for "impacted" sites were greater than for reference sites. Furthermore, concentrations of copper (forestry and mining sites), manganese (agriculture and forestry sites) and selenium (agriculture, forestry and mining sites) exceeded upper sediment quality guideline (SQG) thresholds. These results suggest that agriculture, forestry and metal mining activities are having an influence on the concentrations of sediment-associated metal(loid)s and P in the Quesnel basin. Metal(loid) and P concentrations of sediment collected from the downstream site were not significantly greater than values for the reference sites, and were typically lower than the values for the impacted sites. This suggests that the cumulative effects of agriculture, forestry and mining activities in the QRB are presently not having a measureable effect at the river basin-scale. The lack of a cumulative effect at the basin-scale is thought to reflect: (i) the relatively recent occurrence of land use disturbances in this basin; (ii) the dominance of sediment contributions from natural forest and agriculture; and (iii) the potential for storage of contaminants on floodplains and other storage elements between the locations of disturbance activities and the downstream sampling site, which may be attenuating the disturbance signal. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Fluvial response to the last Holocene rapid climate change in the Northwestern Mediterranean coastlands

    Science.gov (United States)

    Degeai, Jean-Philippe; Devillers, Benoît; Blanchemanche, Philippe; Dezileau, Laurent; Oueslati, Hamza; Tillier, Margaux; Bohbot, Hervé

    2017-05-01

    The variability of fluvial activity in the Northwestern Mediterranean coastal lowlands and its relationship with modes of climate change were analysed from the late 9th to the 18th centuries CE. Geochemical analyses were undertaken from a lagoonal sequence and surrounding sediments in order to track the fluvial inputs into the lagoon. An index based on the K/S and Rb/S ratios was used to evidence the main periods of fluvial activity. This index reveals that the Medieval Climate Anomaly (MCA) was a drier period characterized by a lower fluvial activity, while the Little Ice Age (LIA) was a wetter period with an increase of the river dynamics. Three periods of higher than average fluvial activity were evidenced at the end of the first millennium CE (ca. 900-950 cal yr CE), in the first half of the second millennium CE (ca. 1150-1550 cal yr CE), and during the 1600s-1700s CE (ca. 1650-1800 cal yr CE). The comparison of these fluvial periods with other records of riverine or lacustrine floods in Spain, Italy, and South of France seems to indicate a general increase in fluvial and flood patterns in the Northwestern Mediterranean in response to the climate change from the MCA to the LIA, although some episodes of flooding are not found in all records. Besides, the phases of higher than average fluvial dynamics are in good agreement with the North Atlantic cold events evidenced from records of ice-rafted debris. The evolution of fluvial activity in the Northwestern Mediterranean coastlands during the last millennium could have been driven by atmospheric and oceanic circulation patterns.

  6. New Mesoscale Fluvial Landscapes - Seismic Geomorphology and Exploration

    Science.gov (United States)

    Wilkinson, M. J.

    2013-01-01

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

  7. Tipping points in Anthropocene fluvial dynamics

    Science.gov (United States)

    Notebaert, Bastiaan; Broothaerts, Nils; Verstraeten, Gert; Berger, Jean-François; Houbrechts, Geoffrey

    2016-04-01

    the river partially maintains its braided pattern. The Amblève River in the Belgian Ardennes uplands underwent less dramatic changes. Large parts of the catchment are deforested during the last 700 years, leading to an increase in floodplain sedimentation. Despite this major sediment pulse, change in floodplain morphology remained limited to an increase in bank height. We argue that a combination of floodplain and channel morphology, the fine texture of supplied sediment and the high stream power of channel forming events result is a system that is less sensitive to change. Also the relative short time of impact may play a role. These three examples demonstrate the varying impact of human deforestation on floodplain geomorphology. For the Dijle and Valdaine region this lead to dramatic changes once a certain tipping point is reached. In contrast the Amblève river is more resilient to human impact due to its specific morphological setting. The morphology of the catchments and the nature of supplied sediments plays a major role in the sensitivity of fluvial systems to environmental impact. Once the tipping points are reached, it is difficult for the river to revert to its original state and floodplains remain highly impacted.

  8. Buried late Pleistocene fluvial channels on the inner continental shelf off Vengurla, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    SubbaRaju, L.V.; Krishna, K.S.; Chaubey, A.K.

    with sediments. Cross sectional dimensions between 15 to 100 m width and 2 to 6 m depth suggest a fluvial origin of the channels. These buried channels appear to mark former positions of rivers flowing from the nearby coast and debouching into the Arabian Sea...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-08-01

    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.

  10. River terraces and alluvial fans: The case for an integrated Quaternary fluvial archive

    Science.gov (United States)

    Mather, A. E.; Stokes, M.; Whitfield, E.

    2017-06-01

    The fluvial archive literature is dominated by research on river terraces with appropriate mention of adjacent environments such as lakes. Despite modern sedimentary basins comprising a significant (>88%) volume of distributive fluvial systems, of which alluvial fans (>1 km, dynamic role of alluvial fans within the fluvial landscape and their interaction with river systems, highlighting the potential value of alluvial fans to the wider fluvial archive community. Published literature is used to examine both thematic and geographical based benefits of alluvial fan research that can assist understanding of Quaternary fluvial archives. 3 regional case studies are presented that illustrate the interaction between alluvial fan and river terrace archives at Quaternary time-scales at 3 different stages of landscape evolution. These are i) continuous mountain front alluvial fans interacting with a non incising but laterally eroding axial fluvial system; ii) alluvial fans which transition into fluvial terraces as sedimentary basins shift from net aggradation to net incision and iii) tributary-junction alluvial fans that develop predominantly within incising river valley systems. A simple conceptual model is proposed to summarise the dynamic role of alluvial fans within this landscape context. The alluvial fans act as potential 'buffers' between hillslopes and river terrace records under 'top down' climate-driven high sediment supply and alluvial fan aggradation, and 'couplers' during periods of less sediment (in relation to water) discharge and alluvial fan incision. These dynamics will change with the addition of 'bottom up' controls such as main river incision, which will typically enhance the coupling effect of both systems.

  11. The role of fluvial sediment supply and river-mouth hydrology in the dynamics of the muddy, Amazon-dominated Amapá-Guianas coast, South America: A three-point research agenda

    Science.gov (United States)

    Anthony, Edward J.; Gardel, Antoine; Proisy, Christophe; Fromard, François; Gensac, Erwan; Peron, Christina; Walcker, Romain; Lesourd, Sandric

    2013-07-01

    The morphology and sediment dynamics of the 1500 km-long coast of South America between the mouths of the Amazon and the Orinoco Rivers are largely dependent on the massive suspended-sediment discharge of the Amazon, part of which is transported alongshore as mud banks. These mud banks have an overwhelming impact on the geology, the geomorphology, the ecology and the economy of this coast. Although numerous field investigations and remote sensing studies have considerably enhanced our understanding of the dynamics of this coast over the last three decades, much still remains to be understood of the unique functional mechanisms and processes driving its evolution. Among the themes that we deem as requiring further attention three come out as fundamental. The first concerns the mechanisms of formation of individual mud banks from mud streaming on the shelf off the mouth of the Amazon. An unknown quantity of the fluid mud generated by offshore estuarine front activity is transported shoreward and progressively forms mud banks on the Amapá coast, Brazil. The volume of each mud bank can contain from the equivalent of the annual mud supply of the Amazon to several times this annual sediment discharge. The mechanisms by which individual banks are generated from the Amazon turbidity maximum are still to be elucidated. Areas of research include regional mesoscale oceanographic conditions and mud supply from the Amazon. The second theme is that of variations in rates of migration of mud banks, which influence patterns of coastal accretion. Research emphasis needs to be placed on the analysis of both regional meteorological-hydrodynamic forcing and distant Atlantic forcing, as well as on the hydrology of the large rivers draining the Guyana Shield. The rivers appear to generate significant offshore deflection of mud banks in transit alongshore, through a hydraulic-groyne effect. This may favour both muddy accretion on the updrift coast and downdrift mud liquefaction with

  12. Evidence for the assimilation of ancient glacier organic carbon in a proglacial stream food web

    Science.gov (United States)

    Fellman, Jason; Hood, Eran; Raymond, Peter A.; Hudson, J.H.; Bozeman, Maura; Arimitsu, Mayumi L.

    2015-01-01

    We used natural abundance δ13C, δ15N, and Δ14C to compare trophic linkages between potential carbon sources (leaf litter, epilithic biofilm, and particulate organic matter) and consumers (aquatic macroinvertebrates and fish) in a nonglacial stream and two reaches of the heavily glaciated Herbert River. We tested the hypothesis that proglacial stream food webs are sustained by organic carbon released from glacial ecosystems. Carbon sources and consumers in the nonglacial stream had carbon isotope values that ranged from -30‰ to -25‰ for δ13C and from -14‰ to 53‰ for Δ14C reflecting a food web sustained mainly on contemporary primary production. In contrast, biofilm in the two glacial stream sites was highly Δ14C-depleted (-215‰ to 175‰) relative to the nonglacial stream consistent with the assimilation of ancient glacier organic carbon. IsoSource modeling showed that in upper Herbert River, macroinvertebrates (Δ14C = -171‰ to 22‰) and juvenile salmonids (Δ14C = −102‰ to 17‰) reflected a feeding history of both biofilm (~ 56%) and leaf litter (~ 40%). We estimate that in upper Herbert River on average 36% of the carbon incorporated into consumer biomass is derived from the glacier ecosystem. Thus, 14C-depleted glacial organic carbon was likely transferred to higher trophic levels through a feeding history of bacterial uptake of dissolved organic carbon and subsequent consumption of 14C-depleted biofilm by invertebrates and ultimately fish. Our findings show that the metazoan food web is sustained in part by glacial organic carbon such that future changes in glacial runoff could influence the stability and trophic structure of proglacial aquatic ecosystems.

  13. Infrared Imaging and Modeling of Proglacial Stream Temperature in the Cordillera Blanca, Peru

    Science.gov (United States)

    Baker, E. A.; Lautz, L.; McKenzie, J. M.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.; Glose, A.; Glas, R. L.; Mark, B. G.

    2015-12-01

    In the tropical Andes, glacial meltwater is an important water resource for downstream communities, especially during the dry season. Due to climate change, glacial retreat is accelerating and straining already limited water resources in the region. It is hypothesized that groundwater storage and discharge will play a critical role in sustaining future river flows. To improve our understanding of the hydrologic fluxes in proglacial valleys of the tropical Andes, we monitored a ~1.2 km reach of the Quilcayhuanca River, in the Cordillera Blanca, Peru, using a high resolution infrared (IR) camera and in-stream temperature sensors. We positioned the IR camera on the southern valley wall, 96 m above the valley floor, and collected >700 IR images at 10 minute intervals over 5 days. We deployed 40 temperature sensors along the stream at ~25 m intervals and 10 sensors at additional control points throughout the surrounding valley, recording temperature at 10 minute intervals. Groundwater temperature was recorded in 6 wells in the study area. The reach had diurnal temperature fluctuations from ~4 to 13°C, but did not exhibit large longitudinal temperature differences. Stream temperature profiles within the water column show stream water is well mixed, improving the ability of the IR camera to accurately observe the stream temperature at this research site. Temperature sensors in 4 reach tributaries recorded warmer temperatures than the main channel. The daily temperatures of one tributary fluctuated within the range of the groundwater temperature (~9 to 11°C), while another tributary exhibited a range of ~18°C. A weather station in the study area recorded climate data (air temperature, humidity, wind speed, solar radiation) at 10 minute intervals. We used this field data as input for a spatial and temporal energy balance model of the reach. Our model demonstrates the utility of IR imagery to monitor stream temperatures and improves our understanding of energy fluxes in

  14. Multiescalar studies of fracturing mechanisms in fluvial-lacustrine basins

    Science.gov (United States)

    Carreon-Freyre, D.; Cerca, M.; Hidalgo, C.; Hernandez-Marin, M.

    2007-05-01

    Fracturing of clayey fluvial and lacustrine deposits has become a major problem in several cities of central Mexico. The available data reveals the coexistence of several factors determining fracturing at different scales. As main factors we analyze the variation in compressibility of sediments causing differential deformation and withdrawal of groundwater causing a drop in pore pressure. Compressibility depends on consolidation, a term that in soil mechanics refers to the expulsion of interstitial water, and provokes volume decrease and land subsidence. Although major volume decrease occurs in the vertical scale, consolidation of silty clayey materials generates also horizontal tensile stresses. Considering that this factor can be determining to the generation of fractures, the deformational conditions of clayey, silty and sandy sequences is analyzed integrating their stratigraphy and mechanical characteristics. A particular emphasis is made in the mineralogical heterogeneity of the clay fraction that can be related to compressibility variations and can generate micro-fracturing by differential deformation. As study case we analyze the mechanical and geological properties of two sedimentary sequences with contrasting hydraulic and mechanical behavior. Our results show that the paleoenvironmental history of sediments can be used to determine a specific type of fracturing. Thus, the fracturing in fluvial lacustrine deposits is not a random phenomenon but is highly dependent of the geological properties of materials.

  15. Water and Sediment Discharges from a Glacier-covered Basin under Maritime Climate in Kamchatka Peninsula, Russia

    OpenAIRE

    Matsumoto, Takane; Chikita, Kazuhisa A.

    2004-01-01

    In order to clarify the characteristics of water and sediment discharges from glacier-covered basins under maritime climate, hydrological observations were carried out within a drainage basin which contains Koryto Glacier in Kamchatka Peninsula, Russia. Water discharge of a proglacial stream near the glacier terminus varied between 3 and 12 m^3 s^[-1] during the summer of 2000. Variation in suspended sediment concentration was positively correlated with water discharge, and values of sediment...

  16. GPR-derived architecture of jökulhlaup sediments, Gígjökull, Iceland

    Science.gov (United States)

    Harrison, Devin; Ross, Neil; Russell, Andrew; Dunning, Stuart

    2017-04-01

    A warming global climate has implications for glacial retreat and meltwater generation. In Iceland, the potential frequency and magnitude of jökulhlaup (glacial outburst flood) hazards from ice-dammed and moraine-dammed lakes may be increased by: (i) increased glacial meltwater production; and (ii) the glacio-isostatic response of the mantle driven by deglaciation, which is hypothesised to increase volcanic activity. The high peak-discharges of volcanically-induced jökulhlaups in Iceland have the ability to deposit significant volumes of sediment, causing major geomorphic change and societal impacts. Understanding geomorphological process associated with jökulhlaups can assist in predicting and evaluating future jökulhlaup behaviour and impacts. The 2010 Eyjafjallajökull eruption produced multiple jökulhlaups resulting in major sediment deposition and proglacial aggradation. Observations of the timing, scale and hydraulic properties of these jökulhlaups during the eruption have provided a unique opportunity to investigate the impact of ice-rich meltwater flows on the proglacial environment. Using low-frequency (40 MHz) ground penetrating radar (GPR) and differential GPS (dGPS) surveys of the Gígjökull basin, this study has: (1) geophysically characterised the thick sequence of sedimentary deposits associated with the Eyjafjallajökull eruption, to test conceptual models of jökulhlaup deposition; and (2) quantified post-depositional (2010-2016) elevation change, to evaluate the role of buried ice on post-jökulhlaup landscape response and recovery. The jökulhlaup deposits are characterised by three prominent sediment sub-units, delimited by strong continuous reflectors, and displaying discontinuous undulating reflections (indicating the presence of dunes or anti-dunes). The structures within these sub-units provide insight into the fluvial processes associated with multiple high-magnitude flood events and their relation to the hydraulic properties and

  17. Exit and Paradise Creek Fluvial Features, 1950

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset presents a delineation of the maximum extent of fluvial occupation detectable from vegetation patterns at Exit and Paradise Creeks in Kenai Fjords...

  18. Competing roles of air temperature and summer precipitation events on proglacial stream discharges in Chhota Shigri Glacier catchment, Indian Himalaya

    Science.gov (United States)

    AL, R.

    2016-12-01

    It has been widely recognized that western Himalayan region depends heavily on glacier and snow melt for its water needs. This is true especially for the Chenab sub-basin and more generally for other sub-catchments of the mighty Indus catering to the water demands of millions of stake holders who depend on this water resource. However, there are very few studies available to understand high altitude glaciated catchments, the climatic controls over their flow regimes, and their dependency on glacier mass balances, mainly because of poor access. Hence, the proglacial stream discharges from Chhota Shigri Glacier, a representative glacier of western Himalayan region has been analyzed for understanding the impact of rising air temperatures and highly variable summer precipitation events on discharges that are sourced majorly from snow melt and glacier wastage. This study, for the first time attempts to understand the factors influencing the interannual, subseasonal, and the diurnal variability observed in this representative catchment over four ablation seasons (2010-2013), by monitoring solar radiation, air temperature, summer precipitation, albedo and transient snow cover. The proglacial discharge is governed by air temperatures and albedo-enhancing summer precipitation events, which also enhances transient snow cover. While, the positive mass balance years gave rise to lesser proglacial discharges in comparison to negative mass balance years, lesser winter accumulation was compensated by the lower ablation resulting summer snowfall events in some years. While rising summer air temperatures give rise to glacier wastage, the role of melting transient snow cover on stream discharge is highly significant, especially for positive mass balance years. The pronounced interannual variations and the decreased proglacial discharge in comparison to 1980s suggest that Chhota Shigri Glacier is possibly wasting its way to reach equilibrium to the changed climatic conditions of the

  19. Re-evaluating luminescence burial doses and bleaching of fluvial deposits using Bayesian computational statistics

    Science.gov (United States)

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

    2015-01-01

    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 sediment transport processes. However, comparison of bleaching between samples is complicated by sample-to-sample variation in aliquot size and luminescence sensitivity. Here we begin development of 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 environment, texture, sample depth, depth relative to mean water level, dose rate). Although obvious correlations with predictor variables are absent, there is some suggestion that the best-bleached samples are found close to the modern mean water level, and that the extent of bleaching has changed over the recent past. We hypothesise that sediment deposited near the transition of channel to overbank deposits receives the most sunlight exposure, due to local reworking after deposition. However, nearly all samples are inferred to have at least some well-bleached grains, suggesting that bleaching also occurs during fluvial transport.

  20. Quantification of fluvial response to tectonic deformation in the Central Pontides, Turkey; inferences from OSL dating of fluvial terraces

    Science.gov (United States)

    McClain, Kevin; Yıldırım, Cengiz; Çiner, Attila; Akif Sarıkaya, M.; Şahin, Sefa; Özcan, Orkan; Güneç Kıyak, Nafiye; Öztürk, Tuǧba

    2017-04-01

    From Late Miocene to present, Anatolia's rapid counterclockwise movement, which increases in velocity towards the Hellenic Arc, has formed the North Anatolian Fault (NAF), a dextral transform fault along the Anatolia-Eurasia plate boundary and the northern margin of the Central Anatolian Plateau (CAP). A zone of transpression referred to as the Central Pontides exists between the broad restraining bend of the NAF and the Black Sea Basin, uplifting what is interpreted as a detached flower structure. Dating of Quaternary landforms in the eastern flank of the Central Pontides has helped to understand its recent deformation. However, in the western flank of the Central Pontides there is an absence of Quaternary studies, relatively quiet modern seismicity, and difficulties locating or observing fault scarps. This led us to use optically stimulated luminescence dating (OSL-dating) of fluvial terrace sediments and the study of geomorphic features to gain insight into the influence of climate and tectonics on landscape evolution of this area. In this area, the Filyos River crosses the Karabük Fault (reverse fault) and deeply incises a gorge through the Karabük Range before flowing towards the Black Sea. In the gorge an abundance of indicators of tectonic deformation were mapped, such as hanging valleys, wind gaps, bedrock gorges, landslides, steep V-shaped channels, tilted basins, as well as fluvial strath terraces. In particular, strath terraces of at least 8 levels within just 1.5 km of horizontal distance were examined. We used OSL-dating to estimate five deposition ages of fluvial strath terrace sediments, leading to an estimation of incision and uplift rates over time. Using three samples per terrace with strath elevations of 246 ± 0.2 m, 105.49 ± 0.2 m, 43.6 ± 0.2 m, 15.3 ± 0.2 m and 3.6 ± 0.2 m above the Filyos River, we determined corresponding ages of 841 ± 76 ka, 681 ± 49 ka, 386 ± 18 ka, 88 ± 5.1 ka and 50.9 ± 2.8 ka. Incision rates over time (oldest

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

    Science.gov (United States)

    Marchetti, Mauro

    2002-05-01

    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

  2. Rapid fluvial incision of a late Holocene lava flow: Insights from LiDAR, alluvial stratigraphy, and numerical modeling

    Science.gov (United States)

    Sweeney, Kristin; Roering, Joshua J.

    2016-01-01

    Volcanic eruptions fundamentally alter landscapes, paving over channels, decimating biota, and emplacing fresh, unweathered material. The fluvial incision of blocky lava flows is a geomorphic puzzle. First, high surface permeability and lack of sediment should preclude geomorphically effective surface runoff and dissection. Furthermore, past work has demonstrated the importance of extreme floods in driving incision via column toppling and plucking in columnar basalt, but it is unclear how incision occurs in systems where surface blocks are readily mobile. We examine rapid fluvial incision of the Collier lava flow, an andesitic Holocene lava flow in the High Cascades of Oregon. Since lava flow emplacement ∼1600 yr ago, White Branch Creek has incised bedrock gorges up to 8 m deep into the coherent core of the lava flow and deposited >0.2 km3 of sediment on the lava flow surface. Field observation points to a bimodal discharge regime in the channel, with evidence for both annual snowmelt runoff and outburst floods from Collier glacier, as well as historical evidence of vigorous glacial meltwater. To determine the range of discharge events capable of incision in White Branch Creek, we used a mechanistic model of fluvial abrasion. We show that the observed incision implies that moderate flows are capable of both initiating channel formation and sustaining incision. Our results have implications for the evolution of volcanic systems worldwide, where glaciation and/or mass wasting may accelerate fluvial processes by providing large amounts of sediment to otherwise porous, sediment-starved landscapes.

  3. Constraints in cropping heavy-metal contaminated fluvial sediments

    Energy Technology Data Exchange (ETDEWEB)

    Smilde, K.W.; van Driel, W.; van Luit, B.

    1982-11-01

    Growth and heavy-metal uptake of various food crops and grass cultivated on harbour dredge spoils were studied, and health aspects in consuming the marketable products were discussed. Vegetables (potato, carrot, radish, endive, lettuce) and grass (English ryegrass) performed well on dredge spoils, but small grains (wheat, barley) were affected by manganese deficiency. As compared with crops grown on uncontaminated reference soils, there was a net accumulation of As and heavy metals, especially so Cd, Zn and Cu, and a reduced uptake of Mn. Mainly because of the elevated Cd concentrations of the edible parts, exceeding the guideline of 0.1 mg/kg in fresh matter, the harbour dredge spoils investigated are considered unfit for the production of food crops, but may be used as grassland for dairy cattle. Highest Cd concentrations were attained in leafy vegetables and wheat (grain) and lowest in potato (tuber).

  4. Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt

    OpenAIRE

    Woronko, Barbara; Zieliński, Paweł; Sokołowski, Robert Jan

    2015-01-01

    We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maxi-mum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian ...

  5. The fluvial flux of particulate organic matter from the UK : quantifying in-stream losses and carbon sinks.

    OpenAIRE

    Worrall, F; Burt, T.P.; Howden, N.J.K.

    2014-01-01

    This study considers records of fluvial suspended sediment concentration and its organic matter content from across the United Kingdom from 1974 to 2010. Suspended sediment, mineral concentration and river flow data were used to estimate the particulate organic matter (POM) concentration and flux. Median annual POM flux from the UK was 1596 ktonnes/yr. The POM concentration significantly declined after the European Commission’s Urban Wastewater Directive was adopted in 1991 although the POM f...

  6. Geochemistry of sediments of the eastern continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Mascarenhas, A.; Paropkari, A.L.; Murty, P.S.N.

    . The inter-relationships obtained among the various elements support this conclusion. Similarity in the metal/Al ratios computed for the elements in the continental shelf region with those computed for the fluvial sediments from the adjacent river systems...

  7. Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

    Science.gov (United States)

    Edgar, Lauren; Gupta, Sanjeev; Rubin, David M.; Lewis, Kevin W.; Kocurek, Gary A.; Anderson, Ryan; Bell, James F.; Dromart, Gilles; Edgett, Kenneth S.; Grotzinger, John P.; Hardgrove, Craig; Kah, Linda C.; LeVeille, Richard A.; Malin, Michael C.; Mangold, Nicholas; Milliken, Ralph E.; Minitti, Michelle; Palucis, Marisa C.; Rice, Melissa; Rowland, Scott K.; Schieber, Juergen; Stack, Kathryn M.; Sumner, Dawn Y.; Wiens, Roger C.; Williams, Rebecca M.E.; Williams, Amy J.

    2018-01-01

    This paper characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time, and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture, and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification to determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution, and bedform migration direction, this study concludes that the Shaler outcrop likely records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the northeast, across the surface of a bar that migrated southeast. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggests that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry, and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.

  8. Global distribution of fluvial channels on Titan

    Science.gov (United States)

    Langhans, M.; Jaumann, R.; Stephan, K.; Brown, R. H.; Buratti, B. J.; Clark, R.; Baines, K. H.; Nicholson, P. D.; Lorenz, R. D.

    2009-04-01

    The presence of fluvial erosion on Titan's surface is an obvious analogy to Earth. This study investigates the global distribution of fluvial valley systems on Titan. Based on Cassini-RADAR-data we mapped the allocation of channels, their appropriate flow direction and morphological properties. A great variety of morphological valley types ranges from dendritic valleys that certainly developed from precipitation to a more canyon-like valley type whose development is possibly supported by groundwater release. Another type of fluvial valleys resembles terrestrial wadis that evolved as a result of precipitation separated by long-term intervals of dry periods. Furthermore, based on a global Cassini-VIMS-mosaic the allocation of fluvial channels was determined with respect to spectral units. Based on the spectral signature in the infrared methane windows - expressed as VIMS wavelength ratios composed to a color image (RGB) - three major units can be distinguished: whitish material which is mainly distributed in the topographically high areas indicating equal reflectivity in all atmospheric windows; bluish material that exhibits a higher reflectivity at shorter atmospheric wavelength windows implying a clear spectral separation from the whitish material, and brownish material characterized by a higher reflectivity in the longer wavelength atmospheric windows that correlates with dunes. The majority of channels are exposed on the bright surface unit while just a few percent of channels are located on the blue and brown surface unit, respectively. Fluvial incision has shaped Titan's surface globally. Nevertheless, from a morphological point of view as well as concerning the associated VIMS-unit fluvial shaping is not uniform. The global distribution of channels provides unique information about environmental conditions and processes forming Titan's surface. However, to date just 20% of Titans surface are covered with high resolution data, thus, the current results can only

  9. Development of Adygine glacier complex (glacier and proglacial lakes) and its link to outburst hazard

    Science.gov (United States)

    Falatkova, Kristyna; Schöner, Wolfgang; Häusler, Hermann; Reisenhofer, Stefan; Neureiter, Anton; Sobr, Miroslav; Jansky, Bohumir

    2017-04-01

    Mountain glacier retreat has a well-known impact on life of local population - besides anxiety over water supply for agriculture, industry, or households, it has proved to have a direct influence on glacier hazard occurrence. The paper focuses on lake outburst hazard specifically, and aims to describe the previous and future development of Adygine glacier complex and identify its relationship to the hazard. The observed glacier is situated in the Northern Tien Shan, with an area of 4 km2 in northern exposition at an elevation range of 3,500-4,200 m a.s.l. The study glacier ranks in the group of small-sized glaciers, therefore we expect it to respond faster to changes of the climate compared to larger ones. Below the glacier there is a three-level cascade of proglacial lakes at different stages of development. The site has been observed sporadically since 1960s, however, closer study has been carried out since 2007. Past development of the glacier-lake complex is analyzed by combination of satellite imagery interpretations and on-site measurements (geodetic and bathymetric survey). A glacier mass balance model is used to simulate future development of the glacier resulting from climate scenarios. We used the simulated future glacier extent and the glacier base topography provided by GPR survey to assess potential for future lake formation. This enables us to assess the outburst hazard for the three selected lakes with an outlook for possible/probable hazard changes linked to further complex succession/progression (originating from climate change scenarios). Considering the proximity of the capital Bishkek, spreading settlements, and increased demand for tourism-related infrastructure within the main valley, it is of high importance to identify the present and possible future hazards that have a potential to affect this region.

  10. Metal concentrations in urban riparian sediments along an urbanization gradient

    Science.gov (United States)

    Daniel J. Bain; Ian D. Yesilonis; Richard V. Pouyat

    2012-01-01

    Urbanization impacts fluvial systems via a combination of changes in sediment chemistry and basin hydrology. While chemical changes in urban soils have been well characterized, similar surveys of riparian sediments in urbanized areas are rare. Metal concentrations were measured in sediments collected from riparian areas across the urbanization gradient in Baltimore, MD...

  11. Network Dynamic Connectivity for Identifying Hotspots of Fluvial Geomorphic Change

    Science.gov (United States)

    Czuba, J. A.; Foufoula-Georgiou, E.

    2014-12-01

    The hierarchical branching structure of a river network serves as a template upon which environmental fluxes of water, sediment, nutrients, etc. are conveyed and organized both spatially and temporally within a basin. Dynamical processes occurring on a river network tend to heterogeneously distribute fluxes on the network, often concentrating them into "clusters," i.e., places of excess flux accumulation. Here, we put forward the hypothesis that places in the network predisposed (due to process dynamics and network topology) to accumulate excess bed-material sediment over a considerable river reach and over a considerable period of time reflect locations where a local imbalance in sediment flux may occur thereby highlighting a susceptibility to potential fluvial geomorphic change. We have developed a framework where we are able to track fluxes on a "static" river network using a simplified Lagrangian transport model and use the spatial-temporal distribution of that flux to form a new "dynamic" network of the flux that evolves over time. From this dynamic network we can quantify the dynamic connectivity of the flux and integrate emergent "clusters" over time through a cluster persistence index (CPI) to assess the persistence of mass throughout the network. The framework was applied to sand transport on the Greater Blue Earth River Network in Minnesota where three hotspots of fluvial geomorphic change have been defined based on high rates of channel migration observed from aerial photographic analysis. Locations within the network with high CPI coincided with two of these hotspots, possibly suggesting that channel migration here is driven by sediment deposition "pushing" the stream into and thus eroding the opposite bank. The third hotspot was not identified by high CPI, but instead is believed to be a hotspot of streamflow-driven change based on additional information and the fact that high bed shear stress coincided with this hotspot. The proposed network

  12. A Middle-Upper Miocene fluvial-lacustrine rift sequence in the Song Ba Rift, Vietnam

    DEFF Research Database (Denmark)

    Lars H., Nielsen; Henrik I., Petersen; Nguyen D., Dau

    2007-01-01

    The small Neogene Krong Pa graben is situated within the continental Song Ba Rift, which is bounded by strike-slip faults that were reactivated as extensional faults in Middle Miocene time. The 500 m thick graben-fill shows an overall depositional development reflecting the structural evolution...... development sedimentation rate outpaced the formation of accommodation space and fluvial activity increased again. During periods when the general sedimentation rate was in balance with the creation of accommodation space the environment changed frequently between lake deposition and intermittent vigorous...

  13. Holocene fluvial geochronologies, global databases and hydrological proxies: rethinking people-river interactions and rapid climate change impacts (Invited)

    Science.gov (United States)

    Macklin, M. G.

    2009-12-01

    The assumption of the constancy of climate over time periods of around a century, which was the basis of much engineering and hydrological forward planning until recently, is now widely felt to be unsatisfactory. This re-evaluation has been prompted by a number of important empirical, interdisciplinary and technological advances in fluvial science research over the last decade that is increasingly being carried out in a global framework. Some of the more important developments have included: 1. wider application of high precision sediment-based dating techniques (e.g. OSL) to a greater range of fluvial environments; 2. worldwide database compilation and statistical analysis of 14C dated Holocene fluvial units, enabling the identification of climatic and anthropogenic environmental signals in fluvial sedimentary sequences; and 3. new earth surface observation (e.g. LIDAR) and sediment core analysis (e.g. ITRAX core scanner) techniques that are providing event-scale reconstructions of fluvial environments. Drawing on recent geoarchaeological research in the lower Nile valley, 14C database analysis and comparison of Holocene fluvial records in Europe and New Zealand, and a new 3700-year continuous flood record from the UK reconstructed from fine-grained floodplain sediments, the impact of rapid climate change on riverine societies resulting from monsoon, thermohaline circulation, ENSO and NAO variability is critically reviewed. These studies show that establishing causal relationships between river dynamics and cultural/demographic change is not a straightforward task and identifying possible natural environmental triggers of societal change is especially problematic. A solution may be to stress the inseparable nature of environmental and cultural influences, and view the physical environment as a delimiter of possible action rather than as a prescriptive agency.

  14. Mapping Glacier Dynamics and Proglacial Wetlands with a Multispectral UAV at 5000m in the Cordillera Blanca, Peru

    Science.gov (United States)

    Wigmore, O.; Mark, B. G.

    2015-12-01

    The glaciers of the Cordillera Blanca, Peru are rapidly retreating as a result of rising temperatures, transforming the hydrology and impacting the socio-economic and environmental systems of the Rio Santa basin. Documenting the heterogeneous spatial patterns of these changes to understand processes of water storage and flow is hindered by technologic and logistic challenges. Highly complex topography, cloud cover and coarse spatial resolution limit the application of satellite data while airborne data collection remains costly and potentially dangerous. However, recent developments have made Unmanned Aerial Vehicle (UAV) technology a viable and potentially transformative method for studying glacier dynamics and proglacial hydrology. The extreme altitudes (4000-6700m) of the Cordillera Blanca limit the use of 'off the shelf' UAVs. Therefore we developed a low cost multispectral (visible, near-infrared and thermal infrared) multirotor UAV capable of conducting fully autonomous aerial surveys at elevations over 5000m within the glacial valleys of the Cordillera Blanca. Using this platform we have completed repeat aerial surveys (in 2014 and 2015) of the debris covered Llaca Glacier, generating highly accurate 10-20cm DEM's and 5cm orthomosaics using a structure from motion workflow. Analysis of these data reveals a highly dynamic system with some areas of the glacier losing as much as 16m of vertical elevation, while other areas have gained up to 5m of elevation over one year. The magnitude and direction of these changes appears to be associated with the presence of debris free ice faces and meltwater ponds. Additionally, we have mapped proglacial meadow and wetland systems. Thermal mosaics at 10-20cm resolution are providing novel insights into the hydrologic pathways of glacier meltwater including mapping the distribution of artesian springs that feed these wetland systems. The high spatial resolution of these UAV datasets facilitates a better understanding of the

  15. Impacts of dams on the geomorphodynamics of fluvial systems - Complex system response?

    Science.gov (United States)

    Pöppl, Ronald E.; Keiler, Margreth; Glade, Thomas

    2010-05-01

    In Europe, for more than 5.000 years humans impact fluvial systems in various ways, e.g. also through building dams. These constructions change the interdependencies between the components of the fluvial system. 'Natural (fluvial) systems' are scarce and humans play an active and major role in changing river systems. In return the geomorphic response of fluvial systems like channel bed degradation downstream or sedimentation upstream of dams also affects the human system which again leads to 'human responses' such as building (or abandoning) river engineering structures. Geomorphic response or geomorphic system behavior can change and feature linear or nonlinear/complex behavior depending on the internal systemic structure and system history. The study area, the 'Kaja' River watershed is located in the Eastern part of the Bohemian Massif in Austria (Europe) and drains into the 'Thaya' River which builds the northern border to the Czech Republic in Lower Austria. Furthermore it is eponymous for the local National Park 'Nationalpark Thayatal'. In the study area 14 dams are located in total, 13 along the Kaja River, and one along a tributary river. The study area influenced by dams amounts 1.615 ha. All dams are embankment dams whose cross-sections show hill-shaped forms. They are made of various compositions of soil, sand, clay, and rock. Four dams are currently active, ten are abandoned. The main objectives of this study are to identify if nonlinear/complex geomorphic system behavior occurs in this small and highly dam-affected watershed and to investigate geomorphic effects on fluvial systems due to dams. In order to find nonlinear/complex system behavior those sites are probed in which geomorphic effects due to dams are highly expected: reservoirs, channels, and floodplains. Sedimentary records, numerical modeling and mapping techniques will be used to reveal geomorphic changes and perturbations within the fluvial system. Spatial and temporal reconstructions and

  16. Observations of runoff and sediment and dissolved loads from the Greenland Ice Sheet at Kangerlussuaq, West Greenland, 2007 to 2010

    DEFF Research Database (Denmark)

    Hasholt, Bent; Mikkelsen, Andreas Peter Bech; Nielsen, Morten Holtegaard

    2012-01-01

    Observations from 2007 to 2010 of runoff, sediment and solute delivery from a segment of the Greenland Ice Sheet (GrIS) and the proglacial landscape draining into the fjord at Kangerlussuaq are presented. The observations include at least three jökulhlaups and extreme recordings from 2010...... previously published for 2007 and 2008. The average effective erosion from the catchment was 0.28 mm (min. 0.18 and max. 0.45 mm). The erosion is larger than indicated from most other locations along the GrIS, but in the same order of magnitude as erosion in other glaciated areas at the same latitude, e.......g. Norway. The sandur in the proglacial area acts as a sediment sink for a lot of the sediments from the GrIS....

  17. Freshwater mollusk trophic guilds, composition and distribution in the fluvial landscape of a Brazilian subtropical stream

    Directory of Open Access Journals (Sweden)

    Daniel Pereira

    2011-02-01

    Full Text Available This study verified spatial standards concerning freshwater mollusk trophic guild proportions, composition and distribution along the gradient of fluvial landscape units throughout the Velhaco stream, a subtropical stream located in Rio Grande do Sul state (Brazil. Quantitative collections (presence and absence were made at six sampling stations distributed throughout the stream’s fluvial landscape units: Headspring Sector (SI, Proximal Intermediate Sector (SII, Distal Intermediate Sector (SIII, and Final Sector (SIV. Through the clustering (Jaccard coefficient, group linkage method of centroid and Bray-Curtis polar ordination (similarity measure of Jaccard analyses, a longitudinal species distribution pattern was verified within the gradients of the fluvial landscape units. Suspension feeders were dominant, except at SI. Species compositions at SI and SII (lower species richness were related to their higher altitude, thicker sediments, greater oxygenation and higher pH. On the other hand, species compositions at SIII and SIV (higher species richness were related to their larger hierarchical channel, larger width, larger depth, greater sinuosity, finer sediment and greater aquatic macrophyte richness. Contrary to the RCC predictions, the highest species number was not verified in the stream’s middle stretch, but in the end stretch.

  18. A mineral magnetic characterization of the Plio-Pleistocene fluvial infill of the Heidelberg Basin (Germany)

    Science.gov (United States)

    Scheidt, Stephanie; Egli, Ramon; Frederichs, Thomas; Hambach, Ulrich; Rolf, Christian

    2017-08-01

    The Heidelberg Basin (Germany) hosts a quasi-continuous sedimentary sequence of primarily fluvial sediments with pedogenetic overprints and lacustrine intercalations. This unconsolidated succession has been shown to record a consistent magnetic polarity stratigraphy of the Quaternary and the late Neogene. Previous work has reported that sulphides and high-coercive minerals are the carriers of the remanent magnetization. Here, we provide the results of an extended mineral magnetic study that aims to disentangle the complex magnetic mineralogy. In addition, we assess the reliability of these minerals as carriers of palaeomagnetic signals. A major obstacle to the analysis of the drill cores was the large number of samples that were taken from a total core length of 1150 m. Rapid measurements on bulk samples provided only limited information on the magnetic mineralogy. In contrast, time-intensive methods such as first-order reversal curves (FORCs) or coercivity analyses, for example, yielded valuable information. The combined results of all the analyses consider the heterogeneous compositions of the sediments and indicate a varying palaeoenvironmental history. The Pliocene Iffezheim Formation was formed under alternating reducing and oxidizing conditions. Magnetite, maghemite, haematite and goethite are the predominant magnetic minerals. Sulphides were only preserved under specific conditions. The Pleistocene sediments reflect predominantly reducing conditions during sedimentation and diagenesis. Greigite, pyrite and most likely pyrrhotite have been shown to occur. Taken together, our work provides a detailed environmental magnetic record of the Plio-Pleistocene and elucidates the capabilities and limitations of rock magnetic studies performed on fluvial dominated sedimentary successions.

  19. Large-scale coastal and fluvial models constrain the late Holocene evolution of the Ebro Delta

    Science.gov (United States)

    Nienhuis, Jaap H.; Ashton, Andrew D.; Kettner, Albert J.; Giosan, Liviu

    2017-09-01

    The distinctive plan-view shape of the Ebro Delta coast reveals a rich morphologic history. The degree to which the form and depositional history of the Ebro and other deltas represent autogenic (internal) dynamics or allogenic (external) forcing remains a prominent challenge for paleo-environmental reconstructions. Here we use simple coastal and fluvial morphodynamic models to quantify paleo-environmental changes affecting the Ebro Delta over the late Holocene. Our findings show that these models are able to broadly reproduce the Ebro Delta morphology, with simple fluvial and wave climate histories. Based on numerical model experiments and the preserved and modern shape of the Ebro Delta plain, we estimate that a phase of rapid shoreline progradation began approximately 2100 years BP, requiring approximately a doubling in coarse-grained fluvial sediment supply to the delta. River profile simulations suggest that an instantaneous and sustained increase in coarse-grained sediment supply to the delta requires a combined increase in both flood discharge and sediment supply from the drainage basin. The persistence of rapid delta progradation throughout the last 2100 years suggests an anthropogenic control on sediment supply and flood intensity. Using proxy records of the North Atlantic Oscillation, we do not find evidence that changes in wave climate aided this delta expansion. Our findings highlight how scenario-based investigations of deltaic systems using simple models can assist first-order quantitative paleo-environmental reconstructions, elucidating the effects of past human influence and climate change, and allowing a better understanding of the future of deltaic landforms.

  20. Large-scale coastal and fluvial models constrain the late Holocene evolution of the Ebro Delta

    Directory of Open Access Journals (Sweden)

    J. H. Nienhuis

    2017-09-01

    Full Text Available The distinctive plan-view shape of the Ebro Delta coast reveals a rich morphologic history. The degree to which the form and depositional history of the Ebro and other deltas represent autogenic (internal dynamics or allogenic (external forcing remains a prominent challenge for paleo-environmental reconstructions. Here we use simple coastal and fluvial morphodynamic models to quantify paleo-environmental changes affecting the Ebro Delta over the late Holocene. Our findings show that these models are able to broadly reproduce the Ebro Delta morphology, with simple fluvial and wave climate histories. Based on numerical model experiments and the preserved and modern shape of the Ebro Delta plain, we estimate that a phase of rapid shoreline progradation began approximately 2100 years BP, requiring approximately a doubling in coarse-grained fluvial sediment supply to the delta. River profile simulations suggest that an instantaneous and sustained increase in coarse-grained sediment supply to the delta requires a combined increase in both flood discharge and sediment supply from the drainage basin. The persistence of rapid delta progradation throughout the last 2100 years suggests an anthropogenic control on sediment supply and flood intensity. Using proxy records of the North Atlantic Oscillation, we do not find evidence that changes in wave climate aided this delta expansion. Our findings highlight how scenario-based investigations of deltaic systems using simple models can assist first-order quantitative paleo-environmental reconstructions, elucidating the effects of past human influence and climate change, and allowing a better understanding of the future of deltaic landforms.

  1. Short-term post-wildfire dry-ravel processes in a chaparral fluvial system

    Science.gov (United States)

    Florsheim, Joan L.; Chin, Anne; O'Hirok, Linda S.; Storesund, Rune

    2016-01-01

    Dry ravel, the transport of sediment by gravity, transfers material from steep hillslopes to valley bottoms during dry conditions. Following wildfire, dry ravel greatly increases in the absence of vegetation on hillslopes, thereby contributing to sediment supply at the landscape scale. Dry ravel has been documented as a dominant hillslope erosion mechanism following wildfire in chaparral environments in southern California. However, alteration after initial deposition is not well understood, making prediction of post-fire flood hazards challenging. The majority of Big Sycamore Canyon burned during the May 2013 Springs Fire leaving ash and a charred layer that covered hillslopes and ephemeral channels. Dry-ravel processes following the fire produced numerous deposits in the hillslope-channel transition zone. Field data focus on: 1) deposition from an initial post-wildfire dry-ravel pulse; and 2) subsequent alteration of dry ravel deposits over a seven-month period between September 2013 and April 2014. We quantify geomorphic responses in dry ravel deposits including responses during the one small winter storm that generated runoff following the fire. Field measurements document volumetric changes after initial post-wildfire deposition of sediment derived from dry ravel. Erosion and deposition mechanisms that occurred within dry-ravel deposits situated in the hillslope-channel transition zone included: 1) mobilization and transport of a portion or the entire deposit by fluvial erosion; 2) rilling on the surface of the unconsolidated deposits; 3) deposition on deposits via continued hillslope sediment supply; and 4) mass wasting that transfers sediment within deposits where surface profiles are near the angle of repose. Terrestrial LiDAR scanning point clouds were analyzed to generate profiles quantifying depth of sediment erosion or deposition over remaining dry ravel deposits after the first storm season. This study contributes to the understanding of potential

  2. Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt

    Directory of Open Access Journals (Sweden)

    Woronko Barbara

    2015-06-01

    Full Text Available We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maximum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian and aeolian. Material with traces of aeolian origin predominate in these sediments and this enabled conclusions on the activity of aeolian processes during the Pleniglacial and Late Glacial, and the source of sediment supply to be drawn. Aeolian processes played a major role in the deposition of the lower portions of the fluvial and fluvio-aeolian units. Aeolian material in the fluvial unit stems from aeolian accumulation of fluvial sediments within the valley as well as particles transported by wind from beyond the valley. The fluvio-aeolian unit is composed mainly of fluvial sediments that were subject to multiple redeposition, and long-term, intensive processing in an aeolian environment. In spite of the asynchronous onset of deposition of the fluvio-aeolian unit, it is characterised by the greatest homogeneity of structural and textural characteristics. Although the aeolian unit was laid down simultaneously, it is typified by the widest range of variation in quartz morphoscopic traits. It reflects local factors, mainly the origin of the source material, rather than climate. The duration of dune-formation processes was too short to be reflected in the morphoscopy of quartz grains.

  3. Laboratory theory and methods for sediment analysis

    Science.gov (United States)

    Guy, Harold P.

    1969-01-01

    The diverse character of fluvial sediments makes the choice of laboratory analysis somewhat arbitrary and the pressing of sediment samples difficult. This report presents some theories and methods used by the Water Resources Division for analysis of fluvial sediments to determine the concentration of suspended-sediment samples and the particle-size distribution of both suspended-sediment and bed-material samples. Other analyses related to these determinations may include particle shape, mineral content, and specific gravity, the organic matter and dissolved solids of samples, and the specific weight of soils. The merits and techniques of both the evaporation and filtration methods for concentration analysis are discussed. Methods used for particle-size analysis of suspended-sediment samples may include the sieve pipet, the VA tube-pipet, or the BW tube-VA tube depending on the equipment available, the concentration and approximate size of sediment in the sample, and the settling medium used. The choice of method for most bed-material samples is usually limited to procedures suitable for sand or to some type of visual analysis for large sizes. Several tested forms are presented to help insure a well-ordered system in the laboratory to handle the samples, to help determine the kind of analysis required for each, to conduct the required processes, and to assist in the required computations. Use of the manual should further 'standardize' methods of fluvial sediment analysis among the many laboratories and thereby help to achieve uniformity and precision of the data.

  4. Process regime, salinity, morphological, and sedimentary trends along the fluvial to marine transition zone of the mixed-energy Mekong River delta, Vietnam

    Science.gov (United States)

    Gugliotta, Marcello; Saito, Yoshiki; Nguyen, Van Lap; Ta, Thi Kim Oanh; Nakashima, Rei; Tamura, Toru; Uehara, Katsuto; Katsuki, Kota; Yamamoto, Seiichiro

    2017-09-01

    The fluvial to marine transition zone (FMTZ) is the area of coastal rivers in which sedimentation is controlled by the interaction of fluvial and marine processes. This study examines the FMTZ of the Mekong River delta, along a total channel length of 660 km. Methods consist of collection and analysis of channel bed sediment samples, measurements of channel morphological parameters, and recognition of mangrove, molluscan, and diatom species. The process regime, salinity, morphological, and sedimentary trends recognized were used to define two main tracts for this FMTZ: an upstream, fluvial-dominated tract and a downstream, tide-dominated tract. In more detail, they allow the identification of four subzones, from upstream to downstream: 1) fluvial-dominated, tide-affected; 2) fluvial-dominated, tide-influenced; 3) tide-dominated, fluvial-influenced; and 4) tide-dominated, fluvial-affected. Tide-induced water-level changes affect the entire study area and extend into Cambodia. Measured salinity intrusion extends 15 km upstream of the river mouth during wet season, and 50 km during dry season. Brackish water species of mangroves, mollusks, and diatoms, however, occur landward of these limits, suggesting that highly diluted brackish water may reach 160 km upstream of the river mouth during the dry season. In the fluvial-dominated tract, channels are sinuous and show a seaward-deepening trend, whereas width is relatively constant. In the tide-dominated tract, channels are straight, and show seaward-widening and seaward-shallowing trends. Natural levees are present in the fluvial-dominated, tide-affected subzone, but are replaced by mangroves elsewhere along the FMTZ. In the fluvial-dominated tract, mud content is low, sand grain size fines seaward, and gravelly sand and sand are the dominant facies. In the tide-dominated tract, mud content is high, sand grain size is constant, recycled sand is common, and tidal rhythmites are the dominant facies. Mud pebbles are common

  5. Preliminary Investigations on the Fate of Terrestrial Sediments in the Coastal Ocean Discharged From Taiwanese Small Mountainous Rivers

    Science.gov (United States)

    2009-01-01

    Quantitative links between fluvial sediment discharge, trapped terrigenous flux and sediment accumulation, and implications for temporal and spatial... Sediments in the Coastal Ocean Discharged From Taiwanese Small Mountainous Rivers Kon-Kee Liu Institute of Hydrological & Oceanic Sciences, National...Investigations on the Fate of Terrestrial Sediments in the Coastal Ocean Discharged From Taiwanese Small Mountainous Rivers 5a. CONTRACT NUMBER 5b. GRANT

  6. Evidence of lacustrine sedimentation in the Upper Permian Bijori ...

    Indian Academy of Sciences (India)

    Development of the large Bijori lake body implies generation of accommodation space exceeding the rate of sediment supplied and thus represents locus of high tectonic subsidence. Transition of fluvial sediments with red mudstone and calcareous soil profile in the lower part of the succession to carbonaceous shale and ...

  7. Analysis of Sedimentation Rates in the Densu River Channel: The ...

    African Journals Online (AJOL)

    Sediment is important in determining the morphology of river systems. The Densu basin has come under intense anthropogenic activities such as farming, sand winning, bushfires, among others, which are impacting on the fluvial processes, forms and channel morphology of the river. The study investigated sedimentation of ...

  8. Avulsion history of a Holocene semi-arid river system - Outcrop analogue for thin-bedded fluvial reservoirs in the Rotliegend feather edge

    NARCIS (Netherlands)

    Donselaar, M.E.; Cuevas Gozalo, M.C.; Wallinga, J.

    2017-01-01

    Sedimentation at the terminus of low-gradient river systems in a semi-arid climate setting is characterized by thin-but laterally extensive amalgamated sand sheets. Analysis of absolute age dating with Optically Stimulated Luminescence measurements of fluvial sands in the Holocene Río Colorado

  9. Sedimentary architecture and optical dating of Middle and Late Pleistocene Rhine-Meuse deposits fluvial response to climate change, sea-level fluctuation and glaciation

    NARCIS (Netherlands)

    Busschers, F.S.; Weerts, H.J.T.; Wallinga, J.; Kasse, C.; Cleveringa, P.; de Wolf, H.; Cohen, K.M.

    2005-01-01

    Eight continuous corings in the west-central Netherlands show a 15 to 25 m thick stacked sequence of sandy to gravelly channel-belt deposits of the Rhine-Meuse system. This succession of fluvial sediments was deposited under net subsiding conditions in the southern part of the North Sea Basin and

  10. Sedimentary architecture and optical dating of Middle and Late Pleistocene Rhine-Meuse deposits - Fluvial response to climate change, sea-level fluctuation and glaciation

    NARCIS (Netherlands)

    Busschers, F.S.; Weerts, H.J.T.; Wallinga, J.; Cleveringa, P.; Kasse, C.; Wolf, H.de; Cohen, K.M.

    2005-01-01

    Eight continuous corings in the west-central Netherlands show a 15 to 25 m thick stacked sequence of sandy to gravelly channel-belt deposits of the Rhine-Meuse system. This succession of fluvial sediments was deposited under net subsiding conditions in the southern part of the North Sea Basin and

  11. Sedimentary architecture and optical dating of Middle and Late Pleistocene Rhine-Meuse deposits – fluvial response to climate change, sea-level fluctuation and glaciation

    NARCIS (Netherlands)

    Busschers, F.S.; Weerts, H.J.T.; Wallinga, J.; Cleveringa, P.; Kasse, C.; De Wolf, H.; Cohen, K.M.

    2005-01-01

    Eight continuous corings in the west-central Netherlands show a 15 to 25 m thick stacked sequence of sandy to gravelly channel-belt deposits of the Rhine-Meuse system. This succession of fluvial sediments was deposited under net subsiding conditions in the southern part of the North Sea Basin and

  12. Dynamic LiDAR-NDVI classification of fluvial landscape units

    Science.gov (United States)

    Ramírez-Núñez, Carolina; Parrot, Jean-François

    2015-04-01

    The lower basin of the Coatzacoalcos River is a wide floodplain in which, during the wet season, local and major flooding are distinguished. Both types of floods, intermittent and regional, are important in terms of resources; the regional flood sediments enrich the soils of the plains and intermittent floods allow obtaining aquatic resources for subsistence during the heatwave. In the floodplain different abandoned meanders and intermittent streams are quickly colonized by aquatic vegetation. However, from the 1990s, the Coatzacoalcos River floodplain has important topographic changes due to mining, road and bridges construction; erosion and sedimentation requires continuous parcel boundaries along with the increasing demand of channel reparation, embankments, levees and bridges associated to tributaries. NDVI data, LiDAR point cloud and various types of flood simulations taking into account the DTM are used to classify the dynamic landscape units. These units are associated to floods in relation with water resources, agriculture and livestock. In the study area, the first returns of the point cloud allow extracting vegetation strata. The last returns correspond to the bare earth surface, especially in this area with few human settlements. The surface that is not covered by trees or by aquatic vegetation, correspond to crops, pastures and bare soils. The classification is obtained by using the NDVI index coupled with vegetation strata and water bodies. The result shows that 47.96% of the area does not present active vegetation and it includes 31.53% of bare soils. Concerning the active vegetation, pastures, bushes and trees represent respectively 25.59%, 11.14% and 13.25%. The remaining 1.25% is distributed between water bodies with aquatic vegetation, trees and shrubs. Dynamic landscape units' classification represents a tool for monitoring water resources in a fluvial plain. This approach can be also applied to forest management, environmental services and

  13. Proglacial vs postglacial depostional environments, the opposing processes that filled the southern North Sea tunnel valleys

    DEFF Research Database (Denmark)

    Moreau, Julien; Huuse, Mads

    prograding north in opposing direction to the former ice flows whose south­ward flowing meltwater excavated the valleys. The first hypothesis, by analogy with some small eskers introduced the concept of backfilling where the eroded sediments upstream is deposited directly below the ice margin, in a conveyor...... challenged by new observations on the architecture of the valleys and their infill sediments which appear to show many similarities in common with deltaic clinoforms observed in the pre­glacial succession of the southern North Sea. The new model states that the incision and the filling of the valleys...... stratigraphic scheme is immense and a long run project, it would be unique for this period in the region. We intend to solve part of the problem by numerically reconstructing the local landscape with the ice sheet and its isostatic depression. This allows to represent a type-sequence helping the understanding...

  14. Electrical‐hydraulic relationships observed for unconsolidated sediments in the presence of a cobble framework

    National Research Council Canada - National Science Library

    Slater, Lee; Barrash, Warren; Montrey, Jeanette; Binley, Andrew

    2014-01-01

    ... (SIP) response of granular media. We examined the predictions of such a model on unconsolidated coarse fluvial sediments and compared them to those obtained with a modified Kozeny‐Carman (KC) model...

  15. The Gediz River fluvial archive: A benchmark for Quaternary research in Western Anatolia

    Science.gov (United States)

    Maddy, D.; Veldkamp, A.; Demir, T.; van Gorp, W.; Wijbrans, J. R.; van Hinsbergen, D. J. J.; Dekkers, M. J.; Schreve, D.; Schoorl, J. M.; Scaife, R.; Stemerdink, C.; van der Schriek, T.; Bridgland, D. R.; Aytaç, A. S.

    2017-06-01

    The Gediz River, one of the principal rivers of Western Anatolia, has an extensive Pleistocene fluvial archive that potentially offers a unique window into fluvial system behaviour on the western margins of Asia during the Quaternary. In this paper we review our work on the Quaternary Gediz River Project (2001-2010) and present new data which leads to a revised stratigraphical model for the Early Pleistocene development of this fluvial system. In previous work we confirmed the preservation of eleven buried Early Pleistocene fluvial terraces of the Gediz River (designated GT11, the oldest and highest, to GT1, the youngest and lowest) which lie beneath the basalt-covered plateaux of the Kula Volcanic Province. Deciphering the information locked in this fluvial archive requires the construction of a robust geochronology. Fortunately, the Gediz archive provides ample opportunity for age-constraint based upon age estimates derived from basaltic lava flows that repeatedly entered the palaeo-Gediz valley floors. In this paper we present, for the first time, our complete dataset of 40Ar/39Ar age estimates and associated palaeomagnetic measurements. These data, which can be directly related to the underlying fluvial deposits, provide age constraints critical to our understanding of this sequence. The new chronology establishes the onset of Quaternary volcanism at ∼1320ka (MIS42). This volcanism, which is associated with GT6, confirms a pre-MIS42 age for terraces GT11-GT7. Evidence from the colluvial sequences directly overlying these early terraces suggests that they formed in response to hydrological and sediment budget changes forced by climate-driven vegetation change. The cyclic formation of terraces and their timing suggests they represent the obliquity-driven climate changes of the Early Pleistocene. By way of contrast the GT5-GT1 terrace sequence, constrained by a lava flow with an age estimate of ∼1247ka, span the time-interval MIS42 - MIS38 and therefore do not

  16. Spatio-temporal variability and rates of fluvial bedload transport in steep mountain catchments in western Norway

    Science.gov (United States)

    Beylich, Achim A.; Laute, Katja

    2014-05-01

    The timing and rate of fluvial bedload transport are of central importance within sediment budget studies and in many applications in river science and engineering. Bedload transport rates are very difficult to measure and, in many sites, only suspended load and solute data are included in sediment budget studies. During four years (2010 - 2013) detailed field measurements with portable impact sensors as a non-invasive technique for indirectly determining fluvial bedload transport intensity were conducted at several selected channel stretches within two instrumented and supply-limited drainage basin systems (Erdalen and Bødalen) in the steep fjord landscape in western Norway. The selected stream test stretches where impact sensor field measurements were conducted were located (i) downstream of steep channels in headwater areas of the two drainage basin systems Erdalen and Bødalen, (ii) downstream of selected stream channel segments with temporary in-channel storage of bedload material in Erdalen and Bødalen and (iii) at the outlets of the two drainage basin systems Erdalen and Bødalen. The collected impact sensor field data were calibrated with laboratory flume experiments and were combined with field data from continuous discharge monitoring, repeated surveys of channel morphometry and sediment texture, particle tracer measurements, Helley-Smith samplings, underwater videofilming and biofilm analyses. The combination of methods and techniques applied provides detailed insights into the spatio-temporal variability and rates of fluvial bedload transport within Erdalen and Bødalen. Fluvial bedload transport in steep headwater streams is strongly related to sediment delivery from slopes, especially through fluvial transfers in small creeks draining the slope systems and through snow avalanches in spring and debris flows in fall. Channel reaches with temporary in-channel storage of bedload material in the middle parts of the Erdalen and Bødalen drainage basin

  17. Tectonic control on fluvial styles: the Balfour Formation of the Karoo Basin, South Africa

    Science.gov (United States)

    Catuneanu, Octavian; Elango, Henry N.

    2001-04-01

    The Balfour Formation represents a fully fluvial succession of late Late Permian-earliest Triassic age which accumulated in the foredeep of the Karoo Basin during the overfilled phase of the foreland system. The lack of a coeval marine environment within the limits of the preserved Karoo Basin provides an opportunity to study the stratigraphic cyclicity developed during a time when accommodation was solely controlled by tectonics. The Balfour stratigraphy is composed of a succession of six third-order fluvial depositional sequences separated by subaerial unconformities. They formed in isolation from eustatic influences, with a timing controlled by orogenic cycles of loading and unloading. Sediment accumulation took place during stages of flexural subsidence, whereas the bounding surfaces are related to stages of isostatic uplift. The vertical profile of all sequences displays an overall fining-upward trend related to the gradual decrease in topographic slope during orogenic loading. At the same time, an upward change in fluvial styles can be observed within each sequence, from initial higher to final lower energy systems. The actual fluvial styles in each location depend on paleoslope gradients and the position of the stratigraphic section relative to the orogenic front. Proximal sequences show transitions from braided to meandering systems, whereas more distal sequences show changes from sand-bed to fine-grained meandering systems. The average duration of the Balfour stratigraphic cycles was 0.66 My, i.e. six cycles during 4 My. No climatic fluctuations are recorded during this time, with the long-term climatic background represented by temperate to humid conditions.

  18. What can we learn from fluvial incision in high mountains?

    Science.gov (United States)

    Fuchs, Margret; Gloaguen, Richard; Krbetschek, Matthias

    2013-04-01

    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

  19. A Late Pleistocene linear dune dam record of aeolian-fluvial dynamics at the fringes of the northwestern Negev dunefield

    Science.gov (United States)

    Roskin, Joel; Bookman, Revital; Friesem, David; Vardi, Jacob

    2017-04-01

    The paper presents a late Pleistocene aeolian-fluvial record within a linear dune-like structure that partway served as a dune dam. Situated along the southern fringe of the northwestern Negev desert dunefield (Israel) the structure's morphology, orientation, and some of its stratigraphic units partly resemble adjacent west-east extending vegetated linear dunes. Uneven levels of light-colored, fine-grained fluvial deposits (LFFDs) extend to the north and south from the flanks of the studied structure. Abundant Epipalaeolithic sites line the fringes of the LFFDs. The LFFD microstructures of fine graded bedding and clay blocky peds indicate sorting and shrinking of saturated clays in transitional environments between low energy flows to shallow standing water formed by dunes damming a mid-sized drainage system. The structure's architecture of interchanging units of sand with LFFDs indicates interchanging dominances between aeolian sand incursion and winter floods. Sand mobilization associated with powerful winds during the Heinrich 1 event led to dune damming downstream of the structure and within the structure to in-situ sand deposition, partial fluvial erosion, reworking of the sand, and LFFD deposition. Increased sand deposition led to structure growth and blockage of its drainage system that in turn accumulated LFFD units up stream of the structure. Extrapolation of current local fluvial sediment yields indicate that LFFD accretion up to the structure's brim occurred over a short period of several decades. Thin layers of Geometric Kebaran (c. 17.5-14.5 ka cal BP) to Harifian (12-11 ka BP) artifacts within the structure's surface indicates intermittent, repetitive, and short term camping utilizing adjacent water along a timespan of 4-6 kyr. The finds directly imply that the NW Negev LFFDs formed in dune-dammed water bodies which themselves were formed following events of vegetated linear dune elongation. LFFD accumulation persisted as a result of dune dam

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

    Science.gov (United States)

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

    2007-01-01

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

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

    Science.gov (United States)

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

    2012-11-01

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

  2. OSL age determinations of Pleistocene fluvial deposits in Central Amazonia

    Directory of Open Access Journals (Sweden)

    Emílio A.A. Soares

    2010-09-01

    Full Text Available Absolute dating methods have been used in chronological studies of geological processes and sedimentary units of Quaternary age in Central Amazonia, Brazil. Although radiocarbon dating has been very useful in archaeological research and soil studies, the temporal interval of this method is inefficient in evaluating the sedimentation aspects and geological events from the beginning of the Quaternary in the Amazon basin. The use of crystal luminescence dating has been one of the most promising tool for determining the absolute dating of Quaternary deposits in the Amazonian region. Optically stimulated luminescence (OSL dating, following the MAR and SAR protocols, in a tectonic-sedimentary study of Quaternary fluvial deposits in the confluence area of the Negro and Solimões rivers, indicated ages from 1.3 (Holocene to about 67.4 kyears (Late Pleistocene for these sediments. Low radioactive isotope concentrations were found about 2ppm for 235U and 238U; 5ppm for 232Th; and the 40K concentrations were almost zero. A comparison was made between MAR and SAR protocols taking into account the fluvial depositional process.Métodos de datação absoluta têm sido usados em estudos cronológicos de processos geológicos e unidades sedimentares de idade quaternária na Amazônia Central, Brasil. Embora as datações pelo 14C tenham sido muito úteis na pesquisa arqueológica e estudos de solos, o intervalo de tempo abrangido por este método é ineficiente para avaliar aspectos da sedimentação e eventos geológicos do início do Quaternário na bacia Amazônica. O uso da datação por luminescência de cristais tem sido uma das ferramentas mais promissoras para a determinação da idade absoluta de depósitos quaternários na região amazônica. A datação por luminescência opticamente estimulada (LOE, seguindo os protocolos MAR e SAR, em um estudo tectono-sedimentar de depósitos aluviais quaternários da área de confluência dos rios Negro e Solim

  3. Comparing OSL and CN techniques for dating fluvial terraces and estimating surface process rates in Pamir

    Science.gov (United States)

    Fuchs, Margret; Gloaguen, Richard; Pohl, Eric; Sulaymonova, Vasila; Merchel, Silke; Rugel, Georg

    2014-05-01

    The quantification of surface process rates is crucial for understanding the topographic evolution of high mountains. Spatial and temporal variations in fluvial incision and basin-wide erosion enable to decipher the role of tectonic and climatic drivers. The Pamir is peculiar in both aspects because of its location at the western end of the India-Asia collision zone, and its position at the edge of two atmospheric circulation systems, the Westerlies and the Indian Summer Monsoon. The architecture of the Panj river network indicates prominent variations across the main tectonic structures of the Pamir. The trunk stream, deflects from the predominantly westward river orientation and cuts across the southern and central Pamir domes before doubling back to the west and leaving the orogen. Optically stimulated luminescence (OSL) dating of fluvial terraces reveals short-term sedimentation along the trunk stream during the last ~25 kyr. The agreement of OSL results to new exposure ages based on the cosmogenic nuclide (CN) 10Be confirms accurate terrace age modelling and treatment of incomplete bleaching. The consistent terrace sedimentation and exposure ages suggest also fast terrace abandonment and rapid onset of incision. Considerable differences in terrace heights reflect high spatial variations of fluvial incision, independent of time interval, change in rock type or catchment increase. Highest rates of (5.9 ± 1.1) mm/yr to (10.0 ± 2.0) mm/yr describe the fluvial dynamic across the Shakhdara Dome and that related to the Darvaz Fault Zone. Lower rates of (3.9 ± 0.6) mm/yr to (4.5 ± 0.7) mm/yr indicate a transient stage north of the Yazgulom Dome. Fluvial incision decreases to rates ranging from (1.7 ± 0.3) mm/yr to (3.9 ± 0.7) mm/yr in graded river reaches associated to southern dome boundaries. The pattern agrees to the interpretation of successive upstream river captures across the southern and central Pamir domes inferred from morphometric analyses of river

  4. Determining annual suspended sediment and sediment-associated trace element and nutrient fluxes

    Science.gov (United States)

    Horowitz, A.J.

    2008-01-01

    Suspended sediment is a major factor in the biological and geochemical cycling of trace elements and nutrients in aquatic systems. The design of effective studies involving the collection, processing, and subsequent chemical analysis of suspended sediment requires a clear understanding of the problems associated with using this sample medium. This review summarizes the current state of knowledge relative to the various issues/problems associated with the collection of representative suspended sediment samples in fluvial systems. It also addresses issues associated with accurately determining the concentrations and fluxes of sediment-associated trace elements and nutrients.

  5. Morphodynamic modeling of fluvial channel fill and avulsion time scales during early Holocene transgression, as substantiated by the incised valley stratigraphy of the Trinity River, Texas

    Science.gov (United States)

    Moran, Kaitlin E.; Nittrouer, Jeffrey A.; Perillo, Mauricio M.; Lorenzo-Trueba, Jorge; Anderson, John B.

    2017-01-01

    The Trinity River system provides a natural laboratory for linking fluvial morphodynamics to stratigraphy produced by sea-level rise, because the sediments occupying the Trinity incised valley are well constrained in terms of timing of deposition and facies distribution. Herein, the Trinity River is modeled for a range of base-level rise rates, avulsion thresholds, and water discharges to explore the effects of backwater-induced in-channel sedimentation on channel avulsion. The findings are compared to observed sediment facies to evaluate the capability of a morphodynamic model to reproduce sediment deposition patterns. Base-level rise produces mobile locations of in-channel sedimentation and deltaic channel avulsions. For scenarios characteristic of early Holocene sea-level rise (4.3 mm yr-1), the Trinity fluvial-deltaic system progrades 13 m yr-1, followed by backstepping of 27 m yr-1. Avulsion is reached at the position of maximum sediment deposition (located 108 km upstream of the outlet) after 3,548 model years, based on sedimentation filling 30% of the channel. Under scenarios of greater base-level rise, avulsion is impeded because the channel fill threshold is never achieved. Accounting for partitioning of bed-material sediment between the channel and floodplain influences the timing and location of avulsion over millennial time scales: the time to avulsion is greatly increased. Sedimentation patterns within the valley, modeled and measured, indicate preference toward sandy bed material, and the rates of deposition are substantiated by previous measurements. Although the results here are specific to the Trinity River, the analysis provides a framework that is adaptable to other lowland fluvial-deltaic systems.

  6. Excursions in fluvial (dis)continuity

    Science.gov (United States)

    Grant, Gordon E.; O'Connor, James E.; Safran, Elizabeth

    2017-01-01

    Lurking below the twin concepts of connectivity and disconnectivity are their first, and in some ways, richer cousins: continuity and discontinuity. In this paper we explore how continuity and discontinuity represent fundamental and complementary perspectives in fluvial geomorphology, and how these perspectives inform and underlie our conceptions of connectivity in landscapes and rivers. We examine the historical roots of continuum and discontinuum thinking, and how much of our understanding of geomorphology rests on contrasting views of continuity and discontinuity. By continuum thinking we refer to a conception of geomorphic processes as well as geomorphic features that are expressed along continuous gradients without abrupt changes, transitions, or thresholds. Balance of forces, graded streams, and hydraulic geometry are all examples of this perspective. The continuum view has played a prominent role in diverse disciplinary fields, including ecology, paleontology, and evolutionary biology, in large part because it allows us to treat complex phenomena as orderly progressions and invoke or assume equilibrium processes that introduce order and prediction into our sciences.In contrast the discontinuous view is a distinct though complementary conceptual framework that incorporates non-uniform, non-progressive, and non-equilibrium thinking into understanding geomorphic processes and landscapes. We distinguish and discuss examples of three different ways in which discontinuous thinking can be expressed: 1) discontinuous spatial arrangements or singular events; 2) specific process domains generally associated with thresholds, either intrinsic or extrinsic; and 3) physical dynamics or changes in state, again often threshold-linked. In moving beyond the continuous perspective, a fertile set of ideas comes into focus: thresholds, non-equilibrium states, heterogeneity, catastrophe. The range of phenomena that is thereby opened up to scientific exploration similarly expands

  7. Beaver ponds' impact on fluvial processes (Beskid Niski Mts., SE Poland).

    Science.gov (United States)

    Giriat, Dorota; Gorczyca, Elżbieta; Sobucki, Mateusz

    2016-02-15

    Beaver (Castor sp.) can change the riverine environment through dam-building and other activities. The European beaver (Castor fiber) was extirpated in Poland by the nineteenth century, but populations are again present as a result of reintroductions that began in 1974. The goal of this paper is to assess the impact of beaver activity on montane fluvial system development by identifying and analysing changes in channel and valley morphology following expansion of beaver into a 7.5 km-long headwater reach of the upper Wisłoka River in southeast Poland. We document the distribution of beaver in the reach, the change in river profile, sedimentation type and storage in beaver ponds, and assess how beaver dams and ponds have altered channel and valley bottom morphology. The upper Wisłoka River fluvial system underwent a series of anthropogenic disturbances during the last few centuries. The rapid spread of C. fiber in the upper Wisłoka River valley was promoted by the valley's morphology, including a low-gradient channel and silty-sand deposits in the valley bottom. At the time of our survey (2011), beaver ponds occupied 17% of the length of the study reach channel. Two types of beaver dams were noted: in-channel dams and valley-wide dams. The primary effect of dams, investigated in an intensively studied 300-m long subreach (Radocyna Pond), was a change in the longitudinal profile from smooth to stepped, a local reduction of the water surface slope, and an increase in the variability of both the thalweg profile and surface water depths. We estimate the current rate of sedimentation in beaver ponds to be about 14 cm per year. A three-stage scheme of fluvial processes in the longitudinal and transverse profile of the river channel is proposed. C. fiber reintroduction may be considered as another important stage of the upper Wisłoka fluvial system development. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Floodplains: the forgotten and abused component of the fluvial system

    Directory of Open Access Journals (Sweden)

    Heritage George

    2016-01-01

    Full Text Available River restoration is strongly focussed on in-channel initiatives driven by fisheries interests and a continued desire for river stability. This contrasts greatly with the inherently mobile nature of watercourses. What is often overlooked is the fact that many rivers have developed floodplain units that would naturally operate as integrated functional systems, moderating the effects of extreme floods by distributing flow energy and sediment transport capacity through out of bank flooding. Floodplain utilisation for farming activities and landowner intransigence when it comes to acknowledging that the floodplain is part of the river system, has resulted in floodplains being the most degraded fluvial morphologic unit, both in terms of loss of form and function and sheer levels of spatial impact. The degradation has been facilitated by the failure of regulatory mechanisms to adequately acknowledge floodplain form and function. This is testament to the ‘inward looking’ thinking behind national assessment strategies. This paper reviews the state of floodplain systems drawing on quantitative data from England and Wales to argue for greater consideration of the floodplain in relation to river management. The database is poor and must be improved, however it does reveal significant loss of watercourse-floodplain connectivity linked to direct flood alleviation measures and also to altered flood frequency as a result of river downcutting following river engineering. These latter effects have persisted along many watercourses despite the historic nature of the engineering interventions and will continue to exacerbate the risk of flooding to downstream communities. We also present several examples of the local and wider values of reinstating floodplain form and function, demonstrating major ecological gains, improvement to downstream flood reduction, elevation of water quality status and reductions in overall fine sediment loss from farmland. A re

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-01

    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.

  10. Fluvial channel-belts, floodbasins, and aeolian ergs in the Precambrian Meall Dearg Formation (Torridonian of Scotland): Inferring climate regimes from pre-vegetation clastic rock records

    Science.gov (United States)

    Lebeau, Lorraine E.; Ielpi, Alessandro

    2017-07-01

    The interpretation of climate regimes from facies analysis of Precambrian clastic rocks has been challenging thus far, hindering full reconstructions of landscape dynamics in pre-vegetation environments. Yet, comparisons between different and co-active sedimentary realms, including fluvial-channelised, floodplain, and aeolian hold the potential to shed further light on this thematic. This research discusses a fluvial-aeolian record from the 1.2 Ga Meall Dearg Formation, part of the classic Torridonian succession of Scotland. Tentatively considered to date as a braided-fluvial deposit, this unit is here reappraised as the record of fluvial channel-belts, floodbasins, and aeolian ergs. Fluvial deposits with abundant transitional- to upper-flow regime structures (mostly cross-beds with tangential sets and plane/antidunal beds) and simple, low-relief sediment bars indicate a low-sinuosity, ephemeral style. Floodbasin deposits consist of plane and cross-beds ubiquitously bounded by symmetrical ripples, and rare sediment bars related to the progradation of splay complexes in temporary flooded depressions. Aeolian deposits occur nearby basement topography, and are dominated by large-scale, pin-stripe laminated cross-beds, indicative of intermountain ergs. Neither ephemeral-fluvial nor intermountain aeolian systems can be considered as reliable indicators of local climate, since their sedimentary style is respectively controlled by catchment size and shape, and basin topography relative to groundwater tables. Contrarily, the occurrence of purely clastic - rather than carbonate or evaporitic - floodplain strata can be more confidently related to humid regimes. In brief, this study provides new insight into an overlooked portion of the Torridonian succession of Scotland, and discusses climate inferences for Precambrian clastic terrestrial rocks.

  11. Global effects of agriculture on fluvial dissolved organic matter

    DEFF Research Database (Denmark)

    Graeber, Daniel; Boëchat, Iola; Encina, Francisco

    2015-01-01

    Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matte...

  12. Quantitative reconstruction of cross-sectional dimensions and hydrological parameters of gravelly fluvial channels developed in a forearc basin setting under a temperate climatic condition, central Japan

    Science.gov (United States)

    Shibata, Kenichiro; Adhiperdana, Billy G.; Ito, Makoto

    2018-01-01

    Reconstructions of the dimensions and hydrological features of ancient fluvial channels, such as bankfull depth, bankfull width, and water discharges, have used empirical equations developed from compiled data-sets, mainly from modern meandering rivers, in various tectonic and climatic settings. However, the application of the proposed empirical equations to an ancient fluvial succession should be carefully examined with respect to the tectonic and climatic settings of the objective deposits. In this study, we developed empirical relationships among the mean bankfull channel depth, bankfull channel depth, drainage area, bankfull channel width, mean discharge, and bankfull discharge using data from 24 observation sites of modern gravelly rivers in the Kanto region, central Japan. Some of the equations among these parameters are different from those proposed by previous studies. The discrepancies are considered to reflect tectonic and climatic settings of the present river systems, which are characterized by relatively steeper valley slope, active supply of volcaniclastic sediments, and seasonal precipitation in the Kanto region. The empirical relationships derived from the present study can be applied to modern and ancient gravelly fluvial channels with multiple and alternate bars, developed in convergent margin settings under a temperate climatic condition. The developed empirical equations were applied to a transgressive gravelly fluvial succession of the Paleogene Iwaki Formation, Northeast Japan as a case study. Stratigraphic thicknesses of bar deposits were used for estimation of the bankfull channel depth. In addition, some other geomorphological and hydrological parameters were calculated using the empirical equations developed by the present study. The results indicate that the Iwaki Formation fluvial deposits were formed by a fluvial system that was represented by the dimensions and discharges of channels similar to those of the middle to lower reaches of

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

    Science.gov (United States)

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

    2010-12-01

    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

  14. Modeling transport and deposition of the Mekong River sediment

    Science.gov (United States)

    Xue, Zuo; He, Ruoying; Liu, J. Paul; Warner, John C.

    2012-01-01

    A Coupled Wave–Ocean–SedimentTransport Model was used to hindcast coastal circulation and fine sedimenttransport on the Mekong shelf in southeastern Asian in 2005. Comparisons with limited observations showed that the model simulation captured the regional patterns and temporal variability of surface wave, sea level, and suspended sediment concentration reasonably well. Significant seasonality in sedimenttransport was revealed. In summer, a large amount of fluvial sediments was delivered and deposited near the MekongRiver mouth. In the following winter, strong ocean mixing, and coastal current lead to resuspension and southwestward dispersal of a small fraction of previously deposited sediments. Model sensitivity experiments (with reduced physics) were performed to investigate the impact of tides, waves, and remotely forced ambient currents on the transport and dispersal of the fluvial sediment. Strong wave mixing and downwelling-favorable coastal current associated with the more energetic northeast monsoon in the winter season are the main factors controlling the southwestward along-shelf transport.

  15. Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California.

    Science.gov (United States)

    Kim, Christopher S; Stack, David H; Rytuba, James J

    2012-07-01

    As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.

  16. Timing of fluvial terrace formation and concomitant travertine deposition in the upper Sutlej River (Tirthapuri, southwestern Tibet) and paleoclimatic implications

    Science.gov (United States)

    Wang, Zhijun; Meyer, Michael C.; Gliganic, Luke A.; Hoffmann, Dirk L.; May, Jan-Hendrik

    2017-08-01

    Travertines are carbonates precipitated from hydrothermal springs and are relatively common on the Tibetan plateau and occur along tectonically active faults. The Karakoram fault system is an active strike-slip fault that extends from the Pamir into southwestern Tibet, where it controls the course of the upper Sutlej River and the occurrence of several hydrothermal springs, including the Tirthapuri hot springs. Multiple fluvial terraces that are partly capped by travertine are preserved in the Tirthapuri area. Four main fluvial terrace levels (labelled as T1 to T4 with increasing height above river) were identified and several meter-thick travertine platforms occur on the current river level as well as the T2 and T3 terraces. Sedimentological and petrographic observations suggest that the travertine platforms were deposited on active floodplains of the paleo- and modern Sutlej River, and preserved from fluvial erosion because travertine precipitation was immediately followed by vertical river-bed incision and thus terrace abandonment. Results of 230Th/U in combination with luminescence dating show that the deposition of travertine platform and river incision that led to the formation of T3 terrace (∼93 m above the Sutlej) took place at ca. 127.5 ka. The development of terrace T2 and overlying travertine platform (∼28 m above the Sutlej) occurred between ca. 10.0 and 8.8 ka. Fluvial incision has arrived at the modern level at least ca. 0.2 ka ago. Both the travertine deposition and major river incision are likely triggered by the intensified Indian summer monsoon and are linked to phases of maximum monsoon strength. During strong monsoon phases, a large quantity of moisture is transported into southwestern Tibet, activating hot springs and thus travertine precipitation, facilitating fluvial incision and stripping off sediments from the regional hill-slopes. At least over the last glacial cycle we suggest that the Tirthapuri travertine and associated fluvial

  17. Monitoring Fluvial Topography at Hyperspatial Resolutions with UAS imagery and Structure from Motion

    Science.gov (United States)

    Carbonneau, P.; James, T. D.; Black, M.

    2012-12-01

    Monitoring is a fundamental task in remote sensing. As measurement technology progresses, there is a growing interest in hyperspatial (<10 cm) resolution topographic data which could allow more detailed investigations into the small scale processes which are the building blocks of large scale geomorphic change. Many geomorphologists are approaching this problem of high resolution topographic monitoring with well-proven technology such as ground-based or airborne LiDAR. However, there is also a growing interest in Structure from Motion (SfM) approaches which use images in order to reconstruct dense topographic point clouds. SfM relies on a new generation of image matching algorithms to deliver digital topographic point clouds with an extremely high level of automation and a very low requirement for specialist photogrammetry knowledge. The result is a low-cost, virtually unsupervised process that could foreshadow a new era of widespread hyperspatial topographic data. However, a widespread usage of SfM in fluvial geomorphology will require a rigorous assessment of the associated errors and limitations, a process which has only just begun. Here we present the findings of an experiment aimed at exploring the fundamental limitations of SfM in a fluvial geomorphology context. Our specific aims are to test the suitability of SfM as a hyperspatial topography production method and to explore the relationships between the number of raw images, the resolution of the raw images and the final quality of the resulting point clouds. We compare topographic point clouds generated from SfM and with LiDAR at two scales. First, a simple experiment was conducted on the Science Site of Durham University where an outdoor building was scanned with terrestrial LiDAR and photographed with a small format camera. Second, a field experiment was conducted on a water-worked pro-glacial braiding plain on the arctic island of Svalbard where imagery was acquired with a small Unmanned Aerial System

  18. Pelagic, hemipelagic and turbidite deposition in the Arabian Sea during the late quaternary : unravelling the signals of eolian and fluvial sediment supply as functions of tectonics, sea-level and climate change by means of end-member modelling of siliciclastic grain-size distributions

    NARCIS (Netherlands)

    Prins, M.A.

    1999-01-01

    Tectonics, sea-level changes and variations in climate are the major controlling factors on the input of terrigenous sediments in ocean basins over long periods of time. Two important mechanisms define the timing of high-frequency changes in the sedimentary record of the late Quaternary:

  19. Impact evaluation of the liquid effluent disposal of the Duque de Caxias Refinery (REDUC) in fluvial waters and sediments, RJ, Brazil; Avaliacao do impacto do descarte de efluentes liquidos da Refinaria Duque de Caxias (REDUC) sobre aguas e sedimentos fluviais, RJ, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Bidone, Edison Dausacker; Santelli, Ricardo Erthal; Cordeiro, Renato Campello [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Gamboa, Carla Maria; Camaz, Fernando Ribeiro; Jorge, Fabricio Goncalves [PETROBRAS/REDUC, Rio de Janeiro, RJ, RJ (Brazil). Refinaria de Duque de Caxias; Carvalho, Maria de Fatima B. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2008-07-01

    The purpose of this work is to assess the contribution of the liquid effluents of the Duque de Caxias Refinery (REDUC) in the water and sediment contamination in the estuarine Iguacu-Sarapui system, a tributary of the Guanabara Bay, Rio de Janeiro, Brazil. Since 2002 is being conducted a quarterly monitoring of some parameters in water, river sediments and treated liquid effluent, such as: pH, suspended solids, total sedimented solids, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total organic carbon, oil and grease (O and G), phenols, sulfide, ammonia, metals and metalloids (V, Cr, Pb, Ni, Cu, Cd, Zn, Hg, As, Se , Co, Fe, Mn), polycyclic aromatic hydrocarbons, coprostanol and cholesterol (indicators of domestic wastes). The obtained results show that the effluents meet the legal standards and the treated liquid effluents from REDUC in the estuarine system have little or no impact on river water quality. The higher levels of contaminants detected in water and sediments samples are directly related to untreated domestic sewage from urban areas. (author)

  20. Quantifying fluvial topography using UAS imagery and SfM photogrammetry

    Science.gov (United States)

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

    2014-05-01

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

  1. Recognition of a fluvial facies in the Pacoota Sandstone and its implications for petroleum exploration

    Science.gov (United States)

    Deckelman, James A.

    A previously unrecognized fluvial facies is present in the Late Cambrian-Early Ordovician Pacoota Sandstone in the north-central and northwestern parts of the Amadeus Basin. This facies forms the base of the P3 unit and correlates directly with the primary oil and gas producing interval in the Pacoota Sandstone at the Mereenie Field. In order to distinguish this facies from overlying facies in the P3, it is proposed that the P3 be divided into a lower dominantly fluvial unit, the P3B, and an upper estuarine and shoreface unit, the P3A. Both units can be mapped for hundreds of kilometers at the surface and in the subsurface throughout the Mereenie Field and adjacent areas. The P3B is interpreted as a deposit that accumulated in a dominantly fluvial environment on the basis of: its locally erosional lower bounding surface; the absence of body fossils and ichnofossils; the lobate, wedge-shaped geometry of the unit; the subarkosic composition of the sandstone; the presence of pebble and cobble conflomerate; abundant early syngenetic hematite; abundant trough cross-sets up to 1.35 m thick; overturned cross-laminae; relatively abundant asymmetrical ripple marks; contorted stratification; beds in excess of 1 m in thickness; and its unimodal paleocurrent distribution. The P3B grades conformably into overlying estuarine and shoreface sediments of the P3A. Anagentic silicification is the most significant diagenetic event affecting the present lateral distribution of primary porosity in the P3B unit. Because the extent of anagenetic silificiation decreases southward, the potential for preservation of primary porosity is greatest near the southern depositional limit of the unit. Secondary porosity in the P3B formed by the dissolution of feldspar. Because the abundance of feldspar is inversely related to grainsize which decreases to the southeast, the potential for development of secondary porosity is greatest near the southeastern depositional limit of the unit.

  2. Insights into organic carbon oxidation potential during fluvial transport from controlled laboratory and natural field experiments

    Science.gov (United States)

    Scheingross, Joel S.; Dellinger, Mathieu; Golombek, Nina; Hilton, Robert G.; Hovius, Niels; Sachse, Dirk; Turowski, Jens M.; Vieth-Hillebrand, Andrea; Wittmann, Hella

    2017-04-01

    Over geologic timescales, the exchange of organic carbon (OC) between the atmosphere, biosphere and geosphere is thought to be a major control on atmospheric carbon dioxide (CO2) concentrations, and hence global climate. The carbon fluxes from the oxidation of rock-derived OC (a CO2 source) and erosion and transport of biospheric OC (a potential CO2 sink) during fluvial transit are approximately the same order of magnitude or larger than those from silicate weathering (France-Lanord and Derry, 1997; Bouchez et al., 2010). Despite field data showing oxidation of OC moving downstream in lowland rivers, it is unclear if losses occur primarily during active fluvial transport within the river, where OC is in continual motion within an aerated environment, or during longer periods when OC is temporarily stored in river floodplains which may be anoxic. This represents a major knowledge gap, as the unknown location of OC oxidation (i.e., river vs. floodplain) limits our ability to develop process-based models that can be employed to predict OC losses, constrain carbon budgets, and unravel links between climate, tectonics, and erosion. To fill this gap, we investigated the potential for OC oxidation in both controlled laboratory experiments and a simplified field setting. We consider both rock-derived and biospheric OC. Our experiments simulated fluvial transport without floodplain storage, allowing mixtures of OC-rich and siliciclastic sediment to be transported for distances of 1000 km in annular flumes while making time-series measurements of OC concentration in both the solid (POC) and dissolved (DOC) loads, as well as measurements of rhenium concentration, which serves as a proxy for the oxidation of rock-derived OC. These transport experiments were compared to static, control experiments where water and sediment in the same proportion were placed in still water. Initial results for transport of OC-rich soil show similar behavior between the transport and static

  3. A linear dune dam - a unique late Pleistocene aeolian-fluvial archive bordering the northwestern Negev Desert dunefield, Israel

    Science.gov (United States)

    Roskin, Joel; Bookman, Revital; Friesem, David; Vardi, Jacob

    2016-04-01

    Interactions between aeolian and fluvial processes, known as aeolian-fluvial (A-F) interactions, play a fundamental role in shaping the surface of the Earth especially in arid zones. The blocking of wadis by dunes (dune-damming) is an A-F interaction that is perceived to be an archive of periods of aeolian 'superiority' on fluvial transport power and has had a strong impact on arid landscapes and prehistoric man since the late Quaternary. The southern fringes of the northwestern Negev dunefield are lined with discontinuous surfaces of light-colored, playa-like, low-energy, fine-grained fluvial deposits (LFFDs). Abundant Epipalaeolithic camp sites mainly border the LFFDs. The LFFDs are understood to be reworked loess-like sediment deposited in short-lived shallow water bodies during the late Pleistocene. These developed adjacently upstream of hypothesized dune dams of wadis that drain the Negev highlands. However, no dune dam structures by the LFFDs have been explicitly identified or analyzed. This paper presents for the first time the morphology, stratigraphy and sedimentology of a hypothesized dune dam. The studied linear-like dune dam structure extends west-east for several hundred meters, has an asymmetric cross-section and is comprised of two segments. In the west, the structure is 3-5 m high, 80 m wide, with a steep southern slope, and is covered by pebbles. Here, its morphology and orientation resembles the prevailing vegetated linear dunes (VLDs) of the adjacent dunefield though its slope angles differ from VLDs. To the south of the structure extends a thick LFFD sequence. In the east the structure flattens and is covered by nebkhas with its southern edge overlapped by LFFD units. The structures' stratigraphy is found to be comprised of a thick LFFD base, overlaid by aeolian and fluvially reworked sand, a thin middle LFFD unit, and a crest comprised of LFFDs, fluvial sand and pebbles. Carbonate contents and particle size distributions of the sediments easily

  4. Fluvial response to climate variations and anthropogenic perturbations for the Ebro River, Spain in the last 4,000 years.

    Science.gov (United States)

    Xing, Fei; Kettner, Albert J; Ashton, Andrew; Giosan, Liviu; Ibáñez, Carles; Kaplan, Jed O

    2014-03-01

    Fluvial sediment discharge can vary in response to climate changes and human activities, which in return influences human settlements and ecosystems through coastline progradation and retreat. To understand the mechanisms controlling the variations of fluvial water and sediment discharge for the Ebro drainage basin, Spain, we apply a hydrological model HydroTrend. Comparison of model results with a 47-year observational record (AD 1953-1999) suggests that the model adequately captures annual average water discharge (simulated 408 m(3)s(-1) versus observed 425 m(3)s(-1)) and sediment load (simulated 0.3 Mt yr(-1) versus observed 0.28 ± 0.04 Mt yr(-1)) for the Ebro basin. A long-term (4000-year) simulation, driven by paleoclimate and anthropogenic land cover change scenarios, indicates that water discharge is controlled by the changes in precipitation, which has a high annual variability but no long-term trend. Modeled suspended sediment load, however, has an increasing trend over time, which is closely related to anthropogenic land cover variations with no significant correlation to climatic changes. The simulation suggests that 4,000 years ago the annual sediment load to the ocean was 30.5 Mt yr(-1), which increased over time to 47.2 Mt yr(-1) (AD 1860-1960). In the second half of the 20th century, the emplacement of large dams resulted in a dramatic decrease in suspended sediment discharge, eventually reducing the flux to the ocean by more than 99% (mean value changes from 38.1 Mt yr(-1) to 0.3 Mt yr(-1)). Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Organic carbon transport through a discontinuous fluvial system in a Mediterranean catchment after a greening-up process

    Science.gov (United States)

    Boix-Fayos, Carolina; Almagro, María; Díaz-Pereira, Elvira; Pérez-Cutillas, Pedro; de Vente, Joris; Martínez-Mena, María

    2017-04-01

    Quantification of different organic carbon pools mobilized by lateral fluxes is important to close organic carbon (OC) budgets at the catchment scale. This quantification helps to identify in which forms OC is transferred, deposited, and mineralized during the erosion cycle. Many Mediterranean mountain catchments have experienced important land use changes in the last 50 years leading to a recovery of the vegetation in many cases. Furthermore, many of them are characterized by stream discontinuity with high runoff rates responding to intensive hydrological pulses. There is a current lack of knowledge on fluvial OC fluxes and their relation to soil organic carbon stocks in these systems. The objective of this research was to quantify the amount of organic carbon transported by these systems in a catchment representative of Mediterranean conditions and to explore how intermittent fluvial systems can affect organic carbon transported by lateral flows. During six years OC fluvial fluxes in a catchment of 77 km2 in SE Spain were monitored. The catchment experienced a greening-up process in the last 50 years through a conversion mainly from agricultural use (decrease 44%) to forest (increase 45%). Data on water discharge, sediment concentration, total organic carbon (OC) of suspended sediments and dissolved organic carbon (DOC) were collected throughout 32 rainfall events and 13 sampling periods with base flow conditions. The data were collected from two monitoring stations located on two nested subcatchments covering permanent and ephemeral flow conditions. We found no significant differences in OC concentrations in suspended sediments (10.1 ± 5 g kg-1) and DOC (0.014 ± 0.010 g kg-1) between the ephemeral and the permanent streams. However, sediment concentration, index of aggregation and silt content of suspended load were significantly higher in the ephemeral stream than in the permanent one. OC concentration of suspended sediments was much lower than OC

  6. Human impacts on fluvial systems - A small-catchment case study

    Science.gov (United States)

    Pöppl, Ronald E.; Glade, Thomas; Keiler, Margreth

    2010-05-01

    Regulations of nearly two-thirds of the rivers worldwide have considerable influences on fluvial systems. In Austria, nearly any river (or) catchment is affected by humans, e.g. due to changing land-use conditions and river engineering structures. Recent studies of human impacts on rivers show that morphologic channel changes play a major role regarding channelization and leveeing, land-use conversions, dams, mining, urbanization and alterations of natural habitats (ecomorphology). Thus 'natural (fluvial) systems' are scarce and humans are almost always inseparably interwoven with them playing a major role in altering them coincidentally. The main objective of this study is to identify human effects (i.e. different land use conditions and river engineering structures) on river bed sediment composition and to delineate its possible implications for limnic habitats. The study area watersheds of the 'Fugnitz' River (~ 140km²) and the 'Kaja' River (~ 20km²) are located in the Eastern part of the Bohemian Massif in Austria (Europe) and drain into the 'Thaya' River which is the border river to the Czech Republic in the north of Lower Austria. Furthermore the 'Thaya' River is eponymous for the local National Park 'Nationalpark Thayatal'. In order to survey river bed sediment composition and river engineering structures facies mapping techniques, i.e. river bed surface mapping and ecomorphological mapping have been applied. Additionally aerial photograph and airborne laserscan interpretation has been used to create land use maps. These maps have been integrated to a numerical DEM-based spatial model in order to get an impression of the variability of sediment input rates to the river system. It is hypothesized that this variability is primarily caused by different land use conditions. Finally river bed sites affected by river engineering structures have been probed and grain size distributions have been analyzed. With these data sedimentological and ecological

  7. Effects of discharge, wind, and tide on sedimentation in a recently restored tidal freshwater wetland

    NARCIS (Netherlands)

    Verschelling, Eelco; van der Deijl, Eveline; van der Perk, Marcel; Sloff, C.J.; Middelkoop, Hans

    2017-01-01

    Sediment deposition is one of the key mechanisms to counteract the impact of sea level rise in tidal freshwater wetlands (TFWs). However, information about sediment deposition rates in TFWs is limited, especially for those located in the transition zone between the fluvially dominated and tidally

  8. Effects of discharge, wind, and tide on sedimentation in a recently restored tidal freshwater wetland

    NARCIS (Netherlands)

    Verschelling, Eelco; van der Deijl, Eveline; van der Perk, Marcel; Sloff, Kees; Middelkoop, Hans

    2017-01-01

    Sediment deposition is one of the key mechanisms to counteract the impact of sea level rise in tidal freshwater wetlands (TFWs). However, information about sediment deposition rates in TFWs is limited, especially for those located in the transition zone between the fluvially dominated and tidally

  9. Estimating the Sediment Yield Due to Bend Migration in Meandering Rivers

    National Research Council Canada - National Science Library

    Thorne, Colin; Sikder, Salam

    2007-01-01

    .... In the United States this is addressed through Regional Sediment Management (RSM). To be effective, RSM needs data on sediment inputs to the fluvial system, including that from bank erosion, which may account for as much as 75% of the load...

  10. Changing fluvial styles in volcaniclastic successions: A cretaceous example from the Cerro Barcino Formation, Patagonia

    Science.gov (United States)

    Umazano, A. Martín; Krause, J. Marcelo; Bellosi, Eduardo S.; Perez, Mariano; Visconti, Graciela; Melchor, Ricardo N.

    2017-08-01

    The Cretaceous Puesto La Paloma (PLPM) and Cerro Castaño (CCM) members (Cerro Barcino Formation, Chubut Group) are pyroclastic-rich, alluvial successions deposited in the Somuncurá-Cañadón Asfalto Basin during sag and endorheic conditions. The PLPM comprises sheet-like tuffaceous sandstone strata, whereas the overlying CCM includes sheet-to ribbon-channel sandstone bodies intercalated within tuffaceous and fine-grained sediments. In this context, the goals of this contribution were: i) to make a detailed documentation of the contrasting sedimentary palaeonvironments; and ii) to infer the allocyclic controls that governed the sedimentation of both units. The study area is located in the western sector of the basin, where six localities, which were studied. Six facies associations were defined including ash-falls, sheet-floods, shallow lakes, aeolian, fluvial channel-belts, and reworked debris-flows. We defined four stratigraphic intervals for the studied sections, denominated 1 to 4 in chronological order of deposition, which increase their thicknesses toward the Puesto Mesa-Cerro León site. The interval 1 (18-42 m thick) corresponds to the PLPM and includes numerous pedogenized sheet-flood deposits, carbonate-rich lacustrine, aeolian sandy facies, and ash-fall beds. The interval 1 is interpreted as an ephemeral and unconfined alluvial system that interacted with aeolian dunes and dry interdune zones. The interval 2 (20-47 m thick) represents the lower part of the CCM. It shows an alternation of fluvial channel-belt deposits and vegetated floodplain facies with sediments originated from sheet-floods, lakes, and few ash-falls and debris-flows. The mean palaeoflow was toward E-SE, except in the northernmost locality where the drainage was towards SW. Proportion of channel-belt bodies ranges from 10 to 36%, reaching higher values in the northern part of the study area, where they are also thicker. The interval 2 represents a permanent, meandering or locally low

  11. Determination of the bedload transport rate in a small proglacial High Arctic stream using direct, semi-continuous measurement

    Science.gov (United States)

    Kociuba, Waldemar

    2017-06-01

    The article presents the results of a 34-day series of direct semi-continuous measurements of the bedload transport, performed during the melt season 2013 in the Scott River catchment (NW part of the Wedel-Jarlsberg Land, Spitsbergen). The daily variability of the bedload transport rates and its relation to the dissolved and suspended load were analysed in two cross-sections located in the lower course of a proglacial gravel-bed river. The bedload flux was measured by means of two 4-module sets of River Bedload Traps (RBT). In the research period, a total of 34 day-long samples of bedload and 34 water samples for the determination of the dissolved and suspended load were collected in each of the two cross-sections, 200 m apart. The measurements showed longitudinal and temporal variability of bedload flux and the remaining components (solutions, suspensions) corresponding with changes in water discharge. The mean daily bedload flux QB in consecutive measurement cross-sections XS amounted to 124 kg d- 1XS I and 59 kg d- 1XS II, respectively, and showed high variability and an evident relationship with temperature. The unequal bedload flux of the two measuring stations XS I and XS II suggests aggradation within the alluvial fan that separates the two reaches. The volume and rate of bedload flux were determined by the frequency of the occurrence of flood flows during which approximately from 59% XS I to 77% XS II of total bedload was discharged. The highest recorded daily values constituted 12% of total bedload flux. Through the cross-section below the alluvial fan, the river discharged approximately 6 million cubic meters (M m3) of water, 3 t of bedload Lb, 2238 t of suspended load Ls, and 613 t of dissolved load Ld. The relationships between the three components of the load suggest a 500-fold excess of suspended load, and a 100-fold excess of dissolved load in relation to bedload flux. High temporal and latitudinal variability of the bedload transport rate resulted

  12. The microfauna assemblages as indicators of paleoenvironmental changes in the Miocene fluvial- lacustrine cycles (NE Duero Basin, Spain

    Directory of Open Access Journals (Sweden)

    A. Herrero-Hernández

    2016-11-01

    Full Text Available The siliclastic and carbonate deposits are interbedded in the Villadiego area (Miocene, NE Duero Basin. They have been subdivided into two high-rank depositional sequences: DDS and CDS. The sedimentary analysis of these units and the study of the microfauna content, mainly ostracods, led to the identification of lacustrine-fluvial interaction systems. The sedimentary characteristics reveal the existence of fluvial systems of gravel, flood plains and lacustrine systems that were interconnected and intimately related in north-south direction. In the sedimentological analysis, thirteen types of fluvial and lacustrine lithofacies and six genetic facies associations were recognized. The top of DDS is the result of lake level risings. The CDS shows a deepening-shallowing cycle. The ostracod micropaleontological analysis of the sediments have been studied, with the aim of reconstructing the palaeoenvironmental evolution of this area. These microfauna assemblages integrated with the analysis of the sedimentary facies allowed to conclude the existence of lakes with a water-bearing level of few tens of meters. A change in the chemical conditions of the waters, which evolved from oligohaline and carbonated to mesohaline and sulphated is concluded.

  13. Fluvial dike breaching due to overtopping: how different is it from dam breaching?

    Science.gov (United States)

    Rifai, Ismail; Erpicum, Sébastien; Archambeau, Pierre; Violeau, Damien; Pirotton, Michel; El kadi Abderrezzak, Kamal; Dewals, Benjamin

    2017-04-01

    .g., seven times faster for a 150 % increase in the inflow discharge). When an equilibrium state is reached at the end of the test, the breach centreline orientation is found consistent with the theory of flow over a lateral weir. In the experiments, the boundary condition at the downstream end of the main channel is a lumped representation of river characteristics downstream of the breach section. In real-world conditions, these river characteristics influence the flow partition between the breach and the main channel. Therefore, we tested several downstream boundary conditions (perforated plane, rectilinear weir and sluice gate). For the same inflow discharge and water levels, they lead to significantly different breach geometries. The findings of this research shed light on key mechanisms occurring in fluvial dike breaching, which differ substantially from those in dam breaching. These specific features need to be incorporated in flood risk analyses involving fluvial dike breaching. This research also delivers a unique experimental database of high resolution continuous monitoring of the breach geometry under various flow conditions. The datasets are freely available for engineers and researchers willing to assess the performance of numerical models to simulate dike breaching and resulting flood. References Müller, C., Frank, P.-J., Hager, W.H. (2016). Dyke overtopping: effects of shape and headwater elevation. Journal of Hydraulic Research, 54(4), 410-422. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2016). Monitoring topography of laboratory fluvial dike models subjected to breaching based on a laser profilometry technique. Proc. International Symposium on River Sedimentation (ISRS), 19-22 September 2016, Stuttgart. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2017a). Overtopping induced failure of non-cohesive, homogenous fluvial dikes. Water Resources

  14. Geomorphology of the Ganges fluvial system in the Himalayan foreland: an update

    Directory of Open Access Journals (Sweden)

    Rajiv Sinha

    2004-12-01

    Full Text Available The Ganges is one of the largest fluvial systems in the world rising from the loftiest Himalaya and draining into the Bay of Bengal. Together with the Brahmaputra, it also constitutes the largest delta in the world before finally meeting the sea. The Ganges system passes through a variety of terrain from the rugged mountains through the flat alluvial plains and the sea margin, and also transects variable climatic zones. As a result, the processes, landforms and stratigraphy are strikingly different in different zones of the system. This paper attempts to provide an update on our understanding of this very large and diverse system. A global effort has been made in the last few decades, and the research has focused on a variety of themes. The mountainous catchments have attracted attention in view of the extent of glaciation and extensive erosional processes. The alluvial plains of the Ganges symbolizes the life line of one of the world's largest population. Consequently, a number of studies have been carried out on the morphology, hydrology including flooding history and sediment transport behaviour of the river system. The alluvial stratigraphy of the large valleys and the interfluves in the plains has provided insight about the sedimentation pattern and response to climate change. The deltaic plain is the final destination of this huge sediment dispersal system before it drains into the sea, and it also records the influence of sea level changes apart from the upstream catchment controls over a period of time.

  15. The Role of Ice Blocks in the Creation of Distinctive Proglacial Landscapes During and Following the November 1996 Glacier-Outburst Flood \\(j\\H{o}kulhlaup\\), Skeidararsandur, Southern Iceland.

    Science.gov (United States)

    Fay, H.

    2001-12-01

    form kettle-scours produced by partial burial and scour during the flood and in situ ice block melt after the flood recedes. Rapid sediment deposition around ice blocks, followed by a lack of reworking, results in the formation of entirely aggradational ice block obstacle shadows and hummocky topography. On radial outwash fans where topography is unconfined, kettle holes and obstacle marks occur in distinct clusters. In areas of high j\\H{o}kulhlaup sediment flux, kettle holes form by the in situ melt of (1) progressively buried ice blocks and (2) small flow incorporated ice blocks. In locations subjected to a high sediment flux and high flow velocities, ice block melt-out till is superimposed onto obstacle marks and kettle holes. This study will provide a better understanding of j\\H{o}kulhlaup impact, which will, in turn, lead to improved j j\\H{o}kulhlaup prediction. Knowledge of associations between ice blocks and the bedforms and facies produced during and following a j\\H{o}kulhlaup will aid j\\H{o}kulhlaup identification and reconstruction in ancient proglacial areas including flood identification within the stratigraphic record.

  16. Overtopping induced failure of noncohesive, homogeneous fluvial dikes

    Science.gov (United States)

    Rifai, Ismail; Erpicum, Sebastien; Archambeau, Pierre; Violeau, Damien; Pirotton, Michel; El Kadi Abderrezzak, Kamal; Dewals, Benjamin

    2017-04-01

    Accurate predictions of breach characteristics are necessary to reliably estimate the outflow hydrograph and the resulting inundation close to fluvial dikes. Laboratory experiments on the breaching of fluvial sand dikes were performed, considering a flow parallel to the dike axis. The breach was triggered by overtopping the dike crest. A detailed monitoring of the transient evolution of the breach geometry was conducted, providing key insights into the gradual and complex processes involved in fluvial dike failure. The breach develops in two phases: (1) the breach becomes gradually wider and deeper eroding on the downstream side along the main channel and (2) breach widening controlled by side slope failures, continuing in the downstream direction only. Increasing the inflow discharge in the main channel, the breach formation time decreases significantly and the erosion occurs preferentially on the downstream side. The downstream boundary condition has a strong influence on the breach geometry and the resulting outflow hydrograph.

  17. Fluvial to Lacustrine Facies Transitions in Gale Crater, Mars

    Science.gov (United States)

    Sumner, Dawn Y.; Williams, Rebecca M. E.; Schieber, Juergen; Palucis, Marisa C.; Oehler, Dorothy Z.; Mangold, Nicolas; Kah, Linda C.; Gupta, Sanjeev; Grotzinger, John P.; Grant, John A., III; hide

    2015-01-01

    NASA's Curiosity rover has documented predominantly fluvial sedimentary rocks along its path from the landing site to the toe of the Peace Vallis alluvial fan (0.5 km to the east) and then along its 8 km traverse across Aeolis Palus to the base of Aeolis Mons (Mount Sharp). Lacustrine facies have been identified at the toe of the Peace Vallis fan and in the lowermost geological unit exposed on Aeolis Mons. These two depositional systems provide end members for martian fluvial/alluvial-lacustrine facies models. The Peace Vallis system consisted of an 80 square kilometers alluvial fan with decimeter-thick, laterally continuous fluvial sandstones with few sedimentary structures. The thin lacustrine unit associated with the fan is interpreted as deposited in a small lake associated with fan runoff. In contrast, fluvial facies exposed over most of Curiosity's traverse to Aeolis Mons consist of sandstones with common dune-scale cross stratification (including trough cross stratification), interbedded conglomerates, and rare paleochannels. Along the southwest portion of the traverse, sandstone facies include south-dipping meter-scale clinoforms that are interbedded with finer-grained mudstone facies, interpreted as lacustrine. Sedimentary structures in these deposits are consistent with deltaic deposits. Deltaic deposition is also suggested by the scale of fluvial to lacustrine facies transitions, which occur over greater than 100 m laterally and greater than 10 m vertically. The large scale of the transitions and the predicted thickness of lacustrine deposits based on orbital mapping require deposition in a substantial river-lake system over an extended interval of time. Thus, the lowermost, and oldest, sedimentary rocks in Gale Crater suggest the presence of substantial fluvial flow into a long-lived lake. In contrast, the Peace Vallis alluvial fan onlaps these older deposits and overlies a major unconformity. It is one of the youngest deposits in the crater, and

  18. Fluvial depositional environment evolving into deltaic setting with marine influences in the buntsandstein of northern vosges (France)

    Science.gov (United States)

    Gall, Jean-Claude

    The Buntsandstein in the Northern Vosges (France) originates mainly in an inland braidplain fluvial environment which passes in the upper part of the sequence into deltaic milieu in the coastal plain along the border of the sea, with the continental environment finally being drowned with the transgression of the shallow sea. The fluvial sedimentation is characterized by the presence of two facies throughout the Buntsandstein : channel facies and overbank plain facies. The channel facies comprises sandy and conglomeratic deposits forming within active streams by strong currents, whereas the overbank plain facies is built up of silty-clayey sandstones or silt/clay originating in stagnant water in abandoned watercourses, ponds, pools and puddles. The significance of particularly the floodplain sediments is subjected to considerable changes throughout the Buntsandstein sequence. There are all stages of transition between overbank plain deposits being only preserved in ghost-like facies as reworked clasts due to effective secondary removal of primarily occasionally formed suspension fines, and an abundance of autochthonous floodplain sediments in the depositional record resulting from favourable conditions of primary origin and secondary preservation. Reworked ventifacts within fluvial channel sediments testify to subordinate aeolian influences in the alluvial plain, with reasonable reworking, however, having removed all in situ traces of wind activity. Declining aridity of palaeoclimate towards the top is indicated by the appearance of violet horizon palaeosols in the Zone-Limite-Violette and the Couches intermédiaires being accompanied by Bröckelbank carbonate breccias originating from concentration of reworked fragments of pedogenic carbonate nodules. Biogenic traces are in the lower part of the sequence mainly present as Planolites burrows in the finer-grained sediments. Palaeosalinities as revealed from boron contents indicate progressively increasing

  19. Dinâmica Glacial e Características Sedimentares Resultantes na Zona Proglacial da Geleira Ecology-Baía do Almirantado, Ilha Rei George Antártica.

    Directory of Open Access Journals (Sweden)

    Kátia Kellem Rosa

    2006-12-01

    Full Text Available A geleira Ecology, localizada na ilha Rei George, ilhas Shetlands do Sul, está sofrendo um processo de rápida retração ao longo das últimas décadas, sendo que no período de 1956 a 1992/95 a geleira retrocedeu 0,37 Km2. Isto gerou um ambiente de deglaciação, com a exposição de várias geoformas na zona proglacial. Este trabalho objetiva estudar o ambiente de deglaciação da zona proglacial da geleira Ecology e seus respectivos depósitos na zona proglacial, além de inferir o regime termo-basal desta geleira. O produto resultante deste trabalho é a criação de um modelo geomorfológico para a zona proglacial da geleira, o qual pode ser usado para comparar com zonas proglaciais de outras geleiras.

  20. Response of a dryland fluvial system to climate–tectonic ...

    Indian Academy of Sciences (India)

    2Department of Earth and Environmental Science, K.S.K.V. Kachchh University, Bhuj, Kachchh 370 001, India. ∗. Corresponding ... Temporal changes in the hydrological condition are manifested in the ... Response of a dryland fluvial system to climate–tectonic perturbations during Late Quaternary 1121 during the Late ...

  1. Influence of fluvial sandstone architecture on geothermal energy production

    NARCIS (Netherlands)

    Willems, C.J.L.; Maghami Nick, Hamidreza M.; Weltje, G.J.; Donselaar, M.E.; Bruhn, D.F.

    2015-01-01

    Fluvial sandstone reservoirs composed of stacked meander belts are considered as potential geothermal resources in the Netherlands. Net-to-gross, orientation and stacking pattern of the channel belts is of major importance for the connectivity between the injection and production well in such

  2. Response of a dryland fluvial system to climate–tectonic ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 125; Issue 6. Response of a dryland fluvial system to climate–tectonic perturbations during the Late Quaternary: Evidence from Rukmawati River basin, Kachchh, western India. Archana Das Falguni Bhattacharya B K Rastogi Gaurav Chauhan Mamata Ngangom ...

  3. The fluvial flux of particulate organic matter from the UK: Quantifying in-stream losses and carbon sinks

    Science.gov (United States)

    Worrall, Fred; Burt, Tim P.; Howden, Nicholas J. K.

    2014-11-01

    This study considers records of fluvial suspended sediment concentration and its organic matter content from across the United Kingdom from 1974 to 2010. Suspended sediment, mineral concentration and river flow data were used to estimate the particulate organic matter (POM) concentration and flux. Median annual POM flux from the UK was 1596 ktonnes/yr. The POM concentration significantly declined after the European Commission's Urban Wastewater Directive was adopted in 1991 although the POM flux after 1992 was significantly higher. Estimates of POM flux were compared to a range of catchment properties to estimate the flux of particulate organic carbon (POC) and particulate organic nitrogen (PON) as they entered rivers and thus estimate the net catchment losses. The total fluvial flux of N from the soil source to rivers was 2209 ktonnes N/yr with 814 ktonnes N lost at the tidal limit, and so leaving 1395 ktonnes N/yr loss to atmosphere from across UK catchments - equivalent to an N2O flux from UK rivers of between 33 and 154 ktonnes (N2O)/yr. The total fluvial flux of carbon from the soil source to rivers for the UK was 5020 ktonnes C/yr; the flux at the tidal limit was 1508 ktonnes C/yr, equivalent to 6.5 tonnes C/km2/yr. Assuming that all the net catchment loss goes into the atmosphere, then the impact of rivers on the atmosphere is 3512 ktonnes C/yr, equivalent to 15.2 tonnes C/km2/yr. The loss of POM from the UK suggests that soil erosion in the UK prevents soil being a net sink of CO2 and is instead a small net source to the atmosphere.

  4. Evaluating the signatures of fluvial, wave, and tidal processes on deltaic deposits in the Cretaceous Western Interior Seaway

    Science.gov (United States)

    Hajek, E. A.; Trampush, S. M.

    2014-12-01

    Characteristic differences in delta morphology suggest different balances of wave, tidal, and fluvial processes on different coastlines. These insights have been used to interpret stratigraphic deposits and reconstruct paleogeography of ancient fluvial-deltaic environments. This work is often accomplished through combined efforts to map the architecture of ancient delta deposits and document the abundance and distribution of sedimentary structures that indicate sediment transport by uni- or bi-directional currents or waves. Statistical tools for quantifying sedimentation patterns in ancient deposits provide an opportunity to directly compare architectural patterns among ancient delta deposits. In order to evaluate the degree to which interpreted influence of waves or tides is manifested as a change in delta architecture, we compare detailed stratigraphic measurements from ancient deposits. Well-studied Cretaceous deltaic deposits in the Western Interior Seaway (USA), including the Ferron and Sego formations, have been interpreted as reflecting wave- and tide-influenced conditions, respectively. Using measurements made in the field and from terrestrial lidar outcrop scans, we compare the compensation index and paleohydraulic reconstructions from distributary channel deposits in order to quantify sedimentary architecture in each unit. Preliminary results suggest that the scaling and architecture of topset, foreset, and prodelta deposits in each of these units may have been broadly similar, despite distinct differences in the abundance of wave- and tidal-indicators present within each unit. This indicates that the presence of traditionally diagnostic deposits, particularly sedimentary structures indicative of fluvial, tidal, or wave processes, may not accurately reflect the balance of these processes acting on paleo-shorelines.

  5. Channel arrangements and depositional styles in the São Lourenço fluvial megafan, Brazilian Pantanal wetland

    Science.gov (United States)

    Assine, Mario Luis; Corradini, Fabrício Anibal; Pupim, Fabiano do Nascimento; McGlue, Michael Matthew

    2014-03-01

    The Brazilian Pantanal is an extensive lowland tropical basin characterized by the presence of fluvial megafans and seasonally-inundated savanna floodplain wetlands. With an area of about 16,000 km2, the São Lourenço is the second largest megafan in the Pantanal. Three distinct fluvial channel styles that formed at different times during the late Quaternary are found here. A geomorphological and sedimentary assessment of these depositional patterns provides valuable insight on the environmental context of their evolution. New optically stimulated luminescence data indicate that the upper five meters of sediment in the São Lourenço megafan has been accumulating since the late Pleistocene. Ancient fan lobes, located in upper and intermediate fan settings, consist of medium- and coarse-grained fluvial sands and exhibit well-preserved distributary braided paleochannels on their surfaces. As the megafan evolved through time, Pleistocene lobes were incised by a prominent valley filled with Holocene-aged meander belt deposits, which consist of silts interbedded with very fine sands and clays. Currently, the incised valley is a zone of sediment bypass. Modern deposition occurs along the distal toe of the megafan system, where lobes characterized by distributary channel-levee ridges are widespread. These features formed by progradation of avulsion belts into a broad swampy floodbasin, which caused the lower portion of the meander belt to be abandoned. The significant differences observed in intra-fan morphology appear to be linked to the variability in effective precipitation. Fan lobes deposited with braided distributary channels occurred under relatively dry conditions in the late Pleistocene. By contrast, aggradational meander belt deposits and lobes with distributary channel-levee ridges formed during fluctuating precipitation conditions of the Holocene, when the Pantanal emerged from deglacial aridity. Modern lobes form under heavy seasonal flooding and deposition

  6. The Fluvial Archives Group: 20 years of research connecting fluvial geomorphology and palaeoenvironments

    Science.gov (United States)

    Cordier, Stéphane; Briant, Becky; Bridgland, David; Herget, Jürgen; Maddy, Darrel; Mather, Anne; Vandenberghe, Jef

    2017-06-01

    The Fluvial Archives Group (FLAG) was formed in 1996 under the auspices of the British Quaternary Research Association (QRA). The rationale for its creation was the desire to bring together those working across timescales encompassing the last few million years to the Holocene and even modern process studies. The principles of uniformitarianism are important in the validation of this grouping of interests, with the modern and recent providing analogues from which the older and longer-timescale sequences can be more readily interpreted. The creation of FLAG occurred in the context of improved understanding of terrestrially-based Quaternary sequences and at a time when knowledge of the environmental significance of river systems had also seen great advances, following several decades of engineering experience and research into the management of such systems. This field was subsequently transformed in the European Union by the Water Framework Directive (WFD, 2000), which promoted a strategy for the re-naturalization of rivers. Above all, the WFD implied the (re-)establishment of an initial, pre-anthropogenic, reference state, the recovery of which was a prime aim. This would be a demanding task, considering that rivers are characterized by constant change, even without anthropogenic intervention. The evidence for and understanding of such change, observable at various timescales, is very much the business of FLAG (see below, section 6).

  7. Signatures of Late Pleistocene fluvial incision in an Alpine landscape

    Science.gov (United States)

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

    2018-02-01

    Uncertainty regarding the relative efficacy of fluvial and glacial erosion has hindered attempts to quantitatively analyse the Pleistocene evolution of alpine landscapes. Here we show that the morphology of major tributaries of the Rhone River, Switzerland, is consistent with that predicted for a landscape shaped primarily by multiple phases of fluvial incision following a period of intense glacial erosion after the mid-Pleistocene transition (∼0.7 Ma). This is despite major ice sheets reoccupying the region during cold intervals since the mid-Pleistocene. We use high-resolution LiDAR data to identify a series of convex reaches within the long-profiles of 18 tributary channels. We propose these reaches represent knickpoints, which developed as regional uplift raised tributary bedrock channels above the local fluvial baselevel during glacial intervals, and migrated upstream as the fluvial system was re-established during interglacial periods. Using a combination of integral long-profile analysis and stream-power modelling, we find that the locations of ∼80% of knickpoints in our study region are consistent with that predicted for a fluvial origin, while the mean residual error over ∼100 km of modelled channels is just 26.3 m. Breaks in cross-valley profiles project toward the elevation of former end-of-interglacial channel elevations, supporting our model results. Calculated long-term uplift rates are within ∼15% of present-day measurements, while modelled rates of bedrock incision range from ∼1 mm/yr for low gradient reaches between knickpoints to ∼6-10 mm/yr close to retreating knickpoints, typical of observed rates in alpine settings. Together, our results reveal approximately 800 m of regional uplift, river incision, and hillslope erosion in the lower half of each tributary catchment since 0.7 Ma.

  8. Quantifying uranium transport rates and storage of fluvially eroded mine tailings from a historic mine site in the Grand Canyon Region

    Science.gov (United States)

    Skalak, K.; Benthem, A. J.; Walton-Day, K. E.; Jolly, G.

    2015-12-01

    The Grand Canyon region contains a large number of breccia pipes with economically viable uranium, copper, and silver concentrations. Mining in this region has occurred since the late 19th century and has produced ore and waste rock having elevated levels of uranium and other contaminants. Fluvial transport of these contaminants from mine sites is a possibility, as this arid region is susceptible to violent storms and flash flooding which might erode and mobilize ore or waste rock. In order to assess and manage the risks associated with uranium mining, it is important to understand the transport and storage rates of sediment and uranium within the ephemeral streams of this region. We are developing a 1-dimensional sediment transportation model to examine uranium transport and storage through a typical canyon system in this region. Our study site is Hack Canyon Mine, a uranium and copper mine site, which operated in the 1980's and is currently experiencing fluvial erosion of its waste rock repository. The mine is located approximately 40km upstream from the Colorado River and is in a deep, narrow canyon with a small watershed. The stream is ephemeral for the upper half of its length and sediment is primarily mobilized during flash flood events. We collected sediment samples at 110 locations longitudinally through the river system to examine the distribution of uranium in the stream. Samples were sieved to the sand size and below fraction (<2mm) and uranium was measured by gamma-ray spectroscopy. Sediment storage zones were also examined in the upper 8km of the system to determine where uranium is preferentially stored in canyon systems. This information will quantify the downstream transport of constituents associated with the Hack Canyon waste rock and contribute to understanding the risks associated with fluvial mobilization of uranium mine waste.

  9. Fluvial response to sub-orbital scale environmental changes in southern French Alps

    Science.gov (United States)

    Bonneau, Lucile; Jorry, Stephan; Toucanne, Samuel; Emmanuel, Laurent

    2013-04-01

    Linkage between landscape processes and deep sea deposits is assumed by rivers transfer. Despite all the efforts of the Source-to-Sink community during the last decade, very few studies permit to link marine sedimentary records with phenomena occurring onland. The Var sedimentary system is a spatial restricted sediment routing system with a very narrow continental shelf and steep slope. This particularity makes the Var an ideal target for studying sediment transfers under glacial climate. Late Quaternary sea level changes didn't modified the size of drainage area and during both highstand and lowstand, the deep submarine fan (Var Sedimentary Ridge) was continuously feed by a single channel directly connected to Var river mouth. Located at the border between Mediterranean and alpine domains, the Var River watershed is characterized by steep slope and rare sediment dams. Several studies during the last 20 years had shown that for centennial to daily scale, turbidity flows are related to Var river floods. Based on the analysis of stable oxygen isotopes and radiocarbon dates we established the first high resolution stratigraphy of 20 meters long turbidite deposits on the Var Sedimentary Ridge. This record covers the last 75 ka of the Var turbiditic activity which directly reflects the hydrological and sediment discharge of the onshore fluvial system. The turbidite frequencies show a multiscale variability : (1) the higher frequency corresponds to Dansgaard-Oeschger oscillations and Heinrich events, and (2) the lower frequency characterizes the amplitude of suborbital-scale variability which seems to be modulated by long term orbital parameters variations. The same pattern is reported for vegetation history of European Mediterranean border. This is consistent with our results which suggest that soil stabilization by vegetation cover plays an important role in the modulation of sediment transfers. Under stadials and Heinrich cold and dry climate, the scarce vegetation

  10. Aram Dorsum, Candidate ExoMars Rover Landing Site: a Noachian Inverted Fluvial Channel System in Arabia Terra Mars

    Science.gov (United States)

    Balme, Matthew; Grindrod, Peter; Sefton-Nash, Elliot; Davis, Joel; Gupta, Sanjeev; Fawdon, Peter

    2016-04-01

    Much of Mars' Noachian-aged southern highlands is dissected by systems of fluvial channels and valleys > 3.7 Ga in age. Arabia Terra, lying between the southern highlands and the northern lowlands, is similarly ancient, yet apparently has few valley networks. This regional lack of valley networks only matches Noachian precipitation predictions from climate models if the Noachian climate was dry and cold [1]. In this scenario, highlands dissection was caused by transient flows of meltwater from large, regionally restricted ice-bodies. However, new results [2,3] show that Arabia Terra is not as poorly dissected as previously thought, and in fact there are extensive networks of inverted channel systems. Here, we describe an example of such a system - Aram Dorsum - which has been studied extensively as an ExoMars Rover candidate landing site. Aram Dorsum is an ~100 km long, 1-2 km wide, branching, flat-topped ridge system, in western Arabia Terra. We have mapped the system using CTX images, DEMs and other data. We interpret the ridge system to be fluvial in origin, preserved in positive relief due to infill and differential erosion; this working hypothesis is used as a conceptual framework for the study. Aram Dorsum is a branching, multi-level, contributory network, set in surrounding floodplains-like material. This demonstrates that it was a relatively long-lived, aggradational fluvial system, rather than an erosional outflow or bedrock-carved fluvial channel. Interestingly, the system shows little evidence for unconfined lateral channel migration, so there must have been significant bank stability. Aram Dorsum was therefore probably once a sizable river and, as just one example of many similar systems, is an exemplar for the middle part of a regional sediment transport system that could have extended from the southern highlands to the northern lowlands. Like Aram Dorsum, many of these other recently-recognized fluvial systems have an origin more consistent with

  11. Assessment of intermediate fine sediment storage in a braided river reach (southern French Prealps)

    OpenAIRE

    Navratil, Oldrich; Legout, C.; Gateuille, D.; Esteves, Michel; Liebault, F.

    2010-01-01

    This paper presents a field investigation on river channel storage of fine sediments in an unglaciated braided river, the Bes River, located in a mountainous region in the southern French Prealps. Braided rivers transport a very large quantity of bedload and suspended sediment load because they are generally located in the vicinity of highly erosive hillslopes. Consequently, these rivers play an important role because they supply and control the sediment load of the entire downstream fluvial ...

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

    Science.gov (United States)

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

    2010-05-01

    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 m³ 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 führende und murfähige Wildbäche in Mittelgebirgsr

  13. FLUVIAL PROCESSES IN ATTACHMENT BARS IN THE UPPER PARANÁ RIVER, BRAZIL

    Directory of Open Access Journals (Sweden)

    Vanessa Cristina Dos Santos

    2017-08-01

    Full Text Available Bars are semi-submerged fluvial forms associated with the availability of sediments and a temporal dynamic, whose dimensions are controlled by the flow and depth of the channel.  Attachment bars are very common in large anabranching river systems and play an important role in island formation and ecology. The Upper Paraná River exhibits an anabranching pattern characterized by channels of different sizes, separated by islands and bars. The objective of this work is to present the processes involved in the formation and development of attachment bars in Santa Rosa Island, situated in Porto Rico, State of Parana, Southern Brazil. Acquisition campaigns were performed to obtain data on channel hydraulics (ADCP equipment, morphometry (Echo-sound profiles and textural parameters (grain-size analyses at high and medium water levels. Santa Rosa Island divides the flow into two channels of distinct hydraulic and sedimentary dynamics. Flow diversion produces a decrease in flow velocity and consequent sediment deposition near the upstream end of Santa Rosa Island. The formation and maintenance of attachment bars in Santa Rosa Island is related to flow competence reduction and the occurrence of divergent currents. Vegetation cover and flow regime control its permanence. 

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

    Science.gov (United States)

    Brown, A. G.

    2008-10-01

    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

  15. Depositional environment of a fan delta in a Vistulian proglacial lake (Skaliska Basin, north-eastern Poland

    Directory of Open Access Journals (Sweden)

    Woronko Barbara

    2013-06-01

    Full Text Available The study reconstructed the environment of a fan delta filling the vast end depression of the Skaliska Basin, and its overlying aeolian deposits. The formation of the large fan delta is associated with the presence of an ice-dammed lake functioning during the retreat of the Vistulian Glaciation (MIS 2. The examined material was collected from five boreholes. Sediments were analysed for their granulometric composition and subjected to analyses of frosting and rounding of quartz grains. Grain size analysis showed that the fan delta deposits are built of sand sediments of very low lateral and vertical variability. The fan delta was supplied with fluvioglacial sediments. Accumulation of sediments occurred in shallow water with a very low-gradient slope. The exposed fan delta became a site conducive to aeolian processes after the lake waters fell and the Skaliska Basin depression dried. Dune deposits overlying the fan were affected by short-distance transport so they did not acquire features typical for aeolian deposits.

  16. High-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps - results from the PROSA project

    Science.gov (United States)

    Hilger, Ludwig; Dusik, Jana-Marie; Heckmann, Tobias; Haas, Florian; Näher, Martin; Philipp, Rumohr; Philipp, Glira; Lucas, Vehling; Michael, Becht

    2016-04-01

    In June 2012, the PROSA-project was initiated with the goal to construct a sediment budget of the Upper Kaunertal Valley, Ötztal Alps, Austria. A unique feature of the project being the dedicated usage of study-area wide multi-volume LiDAR survey data of relatively high density on a meso-scale catchment resulting in a data base of over 4 billion LiDAR measurement points. A high effort was undertaken to produce classified point data as a methodological backbone of the project. Both ALS and georeferenced TLS data as well as other remote sensing and mapping products were used in addition to extensive fieldwork as basis for a regionalization of monitoring-site based measurements to arrive at basin-wide sediment production rates and identification of sediment pathways. Results can now be presented for: Rock fall (plot-based measurement and subsequent model-based regionalization), debris flows (study area-wide direct measurement from LiDAR and analysis of historical orthophotos), rock glaciers (feature-tracking and direct differencing), hillslope channels (plot-based measurements and model-based regionalization) and avalanches (sample site measurement, mapping and extrapolation). Sediment budgets were subsequently constructed for different representative subsystems within the 62.5 km2 catchment. Although also glacier and main channel transport was looked into by the PROSA-project, the presentation will focus on the processes mentioned above.

  17. New age constraints for the Saalian glaciation in northern central Europe: Implications for the extent of ice sheets and related proglacial lake systems

    Science.gov (United States)

    Lang, Jörg; Lauer, Tobias; Winsemann, Jutta

    2018-01-01

    A comprehensive palaeogeographic reconstruction of ice sheets and related proglacial lake systems for the older Saalian glaciation in northern central Europe is presented, which is based on the integration of palaeo-ice flow data, till provenance, facies analysis, geomorphology and new luminescence ages of ice-marginal deposits. Three major ice advances with different ice-advance directions and source areas are indicated by palaeo-ice flow directions and till provenance. The first ice advance was characterised by a southwards directed ice flow and a dominance of clasts derived from southern Sweden. The second ice advance was initially characterised by an ice flow towards the southwest. Clasts are mainly derived from southern and central Sweden. The latest stage in the study area (third ice advance) was characterised by ice streaming (Hondsrug ice stream) in the west and a re-advance in the east. Clasts of this stage are mainly derived from eastern Fennoscandia. Numerical ages for the first ice advance are sparse, but may indicate a correlation with MIS 8 or early MIS 6. New pIRIR290 luminescence ages of ice-marginal deposits attributed to the second ice advance range from 175 ± 10 to 156 ± 24 ka and correlate with MIS 6. The ice sheets repeatedly blocked the main river-drainage pathways and led to the formation of extensive ice-dammed lakes. The formation of proglacial lakes was mainly controlled by ice-damming of river valleys and major bedrock spillways; therefore the lake levels and extends were very similar throughout the repeated ice advances. During deglaciation the lakes commonly increased in size and eventually drained successively towards the west and northwest into the Lower Rhine Embayment and the North Sea. Catastrophic lake-drainage events occurred when large overspill channels were suddenly opened. Ice-streaming at the end of the older Saalian glaciation was probably triggered by major lake-drainage events.

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

    Science.gov (United States)

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

    2014-12-01

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

  19. Coastal sedimentation

    Science.gov (United States)

    Schubel, J. R.

    1980-01-01

    Several important coastal sedimentation problems are identified. Application of existing or anticipated remote sensing techniques to examine these problems is considered. Specifically, coastal fine particle sediment systems, floods and hy hurricanes and sedimentation f of coastal systems, routes and rates of sediment transport on continental shelves, and dredging and dredged material disposal are discussed.

  20. A laser profilometry technique for monitoring fluvial dike breaching in laboratory experiments

    Science.gov (United States)

    Dewals, Benjamin; Rifai, Ismail; Erpicum, Sébastien; Archambeau, Pierre; Violeau, Damien; Pirotton, Michel; El kadi Abderrezzak, Kamal

    2017-04-01

    laser are merged to generate a cloud of points. The DLT-based image processing method uses control points and reference axes, so that no prior knowledge is needed on the position, orientation and intrinsic characteristics of the camera, nor on the laser position. Refraction of the light and laser rays across the water surface needs to be taken into account, because the dike is partially submerged during the experiments. An ad hoc correction is therefore applied using the Snell-Descartes law. For this purpose, planar approximations are used to describe the shape of the water surface. In the presentation, we will discuss the resulting uncertainty and will detail the validation of the developed method based on configurations of known geometry with various complexity. The presented laser profilometry technique allows for a rapid non-intrusive measurement of the dike geometry evolution. It is readily available for laboratory experiments and has proven its performance (Rifai et al. 2017). Further adjustments are needed for its application to cohesive dike material due to the reduced visibility resulting from the higher turbidity of water. References Frank, P.-J., Hager, W.H. (2014). Spatial dike breach: Accuracy of photogrammetric measurement system. Proc. of the International Conference on Fluvial Hydraulics, River Flow 2014, 1647-1654. Pickert, G., Weitbrecht, V., Bieberstein A. (2011). Beaching of overtopped river embankments controlled by apparent cohesion. Journal of Hydraulic Research 49:143-156. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2016). Monitoring topography of laboratory fluvial dike models subjected to breaching based on a laser profilometry technique. Proc. of the International Symposium on River Sedimentation (ISRS): Stuttgart, 19-22 September 2016. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2017). Overtopping induced failure of non

  1. The impact of climate change on sediment delivery from the Jostedalsbreen ice cap, Southern Norway

    Science.gov (United States)

    Bogen, Jim; Xu, Mengzhen; Melvold, Kjetil

    2015-04-01

    one small overdeepening has been observed beneath Nigardsbreen. Hence, sediment transport of this glacier will not be affected notecably. However, calving will become an important factor contributing to ablation for many other glaciers, for example, Tunsbergdalsbreen, Supphellebreen, Bøyabreen, etc. During calving, all the sediment in the glacier sole will melt out. However, a large amount of the sediment will be trapped in the proglacial lakes and not be delivered to the rivers downstream of the lakes. Keywords: climate change, glacial sediment transport, proglacial lakes, glacier hydrology

  2. Surficial geological tools in fluvial geomorphology: Chapter 2

    Science.gov (United States)

    Jacobson, Robert B.; O'Connor, James E.; Oguchi, Takashi

    2016-01-01

    Increasingly, environmental scientists are being asked to develop an understanding of how rivers and streams have been altered by environmental stresses, whether rivers are subject to physical or chemical hazards, how they can be restored, and how they will respond to future environmental change. These questions present substantive challenges to the discipline of fluvial geomorphology, especially since decades of geomorphologic research have demonstrated the general complexity of fluvial systems. It follows from the concept of complex response that synoptic and short-term historical views of rivers will often give misleading understanding of future behavior. Nevertheless, broadly trained geomorphologists can address questions involving complex natural systems by drawing from a tool box that commonly includes the principles and methods of geology, hydrology, hydraulics, engineering, and ecology.

  3. Distribution and Potential Mobility of Selected Heavy Metals in a Fluvial Environment Under the Influence of Tanneries

    Directory of Open Access Journals (Sweden)

    Rodrigues M. L. K.

    2013-04-01

    Full Text Available In this study we evaluated the occurrence of heavy metals in a fluvial environment under the influence of tanneries – the Cadeia and Feitoria rivers basin (RS, south Brazil, highlighting the distribution and potential mobility of the selected elements. Every three months, over one year-period, selected heavy metals and ancillary parameters were analyzed in water and sediment samples taken at ten sites along the rivers. Water analyses followed APHA recommendations, and sediment analyses were based on methods from USEPA (SW846 and European Community (BCR sequential extraction. The determinations were performed by ICP/OES, except for Hg (CV/ETA. Statistical factor analysis was applied to water and sediment data sets, in order to obtain a synthesis of the environmental diagnosis. The results revealed that water quality decreased along the rivers, and mainly on the dry period (January, showing the influence of tannery plants vicinity and flow variations. Except for Fe, Al, and eventually Mn, heavy metal contents in water were in agreement with Brazilian standards. Concerning sediments, Al, Cu, Fe, Ni, Mn, Ti, and Zn concentrations appeared to reflect the base levels, while Cr and Hg were enriched in the deposits from the lower part of the basin. The partition of heavy metals among the sediment geochemical phases showed higher mobility of Mn along the sampling sites, followed by Cr in the lower reach of the basin, most affected by tanneries. Since Cr was predominantly associated to the oxidizable fraction, its potential mobilization from contaminated sediments would be associated to redox conditions. The detection of Hg in the tissue of a bottom-fish species indicated that the environmental conditions are apparently favoring the remobilization of this metal from contaminated sediments.

  4. Transport mechanism for Pb-210, Cs-137 and Pu fallout radionuclides through fluvial-marine systems

    Science.gov (United States)

    Smith, J. N.; Ellis, K. M.

    1982-06-01

    Pb-210, Cs-137 and Pu-239,240 sediment-depth profiles in an anoxic, unbioturbated, estuarine depositional regime at the head of the Saguenay Fjord, Que. exhibit a seasonally-modulated component caused by pulsed inputs of silts and sands during high energy, spring river discharge events superimposed on an ambient depositional pattern of finer grained clays and organic matter. A precise sediment timestratigraphy has been determined by the inverse correlation of the Pb-210 activity with the rate of river discharge during the period, 1963-1976. The historical record of Cs-137 and Pu-239,240 sediment fluxes has been reconstructed through the normalization of fallout radionuclide activities to the excess Pb-210 activity profile. Radionuclide flux geochronologies have been interpreted on the basis of a fluvial-marine transport model which distinguishes between inputs due to direct adsorption of radionuclides onto particles in the water column and inputs resulting from the erosion of particle-associated radionuclides from the drainage basin. Rate constants corresponding to residence times of one year for Cs-137 and Pu-239,240 in the water column and 1500 years for each radionuclide in the drainage basin provide reasonable agreement between the model and experimental results, although there is some evidence for a slightly longer drainage basin residence time for plutonium. Both the threshold for the initial appearance of Pu-238, derived from the atmospheric burnup of a SNAP-9A satellite reactor in 1964, and the magnitude of its isotopic dilution by drainage basin inputs of Pu-239,240 are also in agreement with model predictions.

  5. Assessment of spatiotemporal variations in the fluvial wash-load component in the 21st century with regard to GCM climate change scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Mouri, Goro, E-mail: mouri@rainbow.iis.u-tokyo.ac.jp

    2015-11-15

    For stream water, in which a relationship exists between wash-load concentration and discharge, an estimate of fine-sediment delivery may be obtained from a traditional fluvial wash-load rating curve. Here, we demonstrate that the remaining wash-load material load can be estimated from a traditional empirical principle on a nationwide scale. The traditional technique was applied to stream water for the whole of Japan. Four typical GCMs were selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble to provide the driving fields for the following regional climate models to assess the wash-load component based on rating curves: the Model for Interdisciplinary Research on Climate (MIROC), the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), the Hadley Centre Global Environment Model (HadGEM) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model. The simulations consisted of an ensemble, including multiple physics configurations and different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5), which was used to produce monthly datasets for the whole country of Japan. The impacts of future climate changes on fluvial wash load in Japanese stream water were based on the balance of changes in hydrological factors. The annual and seasonal variations of the fluvial wash load were assessed from the result of the ensemble analysis in consideration of the Greenhouse Gas (GHG) emission scenarios. The determined results for the amount of wash load increase range from approximately 20 to 110% in the 2040s, especially along part of the Pacific Ocean and the Sea of Japan regions. In the 2090s, the amount of wash load is projected to increase by more than 50% over the whole of Japan. The assessment indicates that seasonal variation is particularly important because the rainy and typhoon seasons, which include extreme events, are the dominant seasons. Because fluvial wash-load-component turbidity

  6. Paleobiogeoclimatic scenarios of the Late Quaternary inferred from fluvial deposits of the Quadrilátero Ferrífero (Southeastern Brazil)

    Science.gov (United States)

    Barros, Luiz Fernando de Paula; Coe, Heloísa Helena Gomes; Seixas, Amanda Pacheco; Magalhães, Antônio Pereira, Jr.; Macario, Kita Chaves Damasio

    2016-04-01

    The Quadrilátero Ferrífero is an important mineral province in Southeastern Brazil and has one of the largest iron ore reserves in the world. Previous work in this region has indicated that the formation of fluvial successions with duricrusts coincided with drier/cooler climatic phases alternating with moister/warmer periods during which the formation of fluvial successions without duricrusts occurred. For the construction of this proposal, ages of fluvial sediments obtained through Optically Stimulated Luminescence (OSL) were associated with data from the literature on paleobioclimatic scenarios. Therefore, using these observations as a starting point, this paper aims to investigate evidence of bioclimatic oscillations obtained directly from the fluvial successions and discuss its influence on the geomorphogenis of local river valleys. For this purpose, phytolith, carbon isotope and granulometric analyses were carried out, as well as dating of sediments using OSL and of soil organic matter through radiocarbon. The results show that in the oldest depositional succession (DS1 - about 34ka) the predominant phytoliths are those of bulliform polyedric, elongate, acicular and globular granulate types and δ13C values are typical of C3 plants. On the other hand, despite having a similar phytolith assemblage (abundance of bulliform polyedric, elongate, bulliform cuneiform, acicular, globular psilate and bilobate flat/concave types), the fluvial successions associated with significant conglomeratic duricrusts (DS2 and DS3) present a dominance of δ13C values characteristic of C4 plants. The Bi index indicates water stress in all the successions, and the Ic index suggests decreasing temperatures with depth in DS3. Thus, the three fluvial successions indicate a savanna-like environment, but depositional successions DS2 (∼27ka) and DS3 show drier/cooler climatic conditions when compared to DS1 and to the present-day regime. Both scenarios evolved under conditions of the

  7. Age of Terrestrial Biomarkers in Fluvial Transit Across the Andes-Amazon Reveal Timescales of Carbon Storage and Turnover

    Science.gov (United States)

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

    2014-12-01

    Environmental signatures carried by fluvially-exported terrestrial organic matter are shaped by storage, remineralization and replacement at various spatial and temporal scales. Uncertainties in the timescales of these processes are key caveats in the accurate interpretation of sedimentary records. As part of a multi-isotope leaf wax biomarker project, we report the age of biomarkers transported by rivers from mountain to floodplain across the Andes-Amazon transition in southern Peru. We tracked the age of organic carbon using the radiocarbon (14ΔC) composition of plant leaf waxes extracted from particulate organic carbon (POC) in river suspended sediments. Leaf waxes from POC are younger in mountain headwaters (1000 yrs). Downstream aging is associated with the greater storage potential and residence times in lowland mineral soils and sedimentary sequences that include Pleistocene age eroding river terraces. Given three key observations that 1) carbon loading in suspended sediment does not substantively change from Andes to Amazon, 2) ~80% of sediment is sourced in the Andes, and 3) age increases downstream (this study); we find proof of the decoupling of organic carbon from sediment, which we attribute to loss of Andean carbon and replacement during transport.

  8. Regional and long-term patterns of lead concentrations in fluvial, marine and terrestrial systems and humans in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Hagner, C. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik

    2000-07-01

    Lead contamination of abiotic and biotic systems has been studied closely since the early 1970s, when lead was firstly perceived as an environmental problem. Lead emission reduction policies were implemented throughout Europe during that time. Nonetheless, analyses of lead loads in aquatic systems, such as the river Elbe, showed no decline over time in either suspended matter or surface sediments. Regional differences in lead concentrations of fluvial systems were found, due to tidal influence, runoff and local emissions. Lead contamination of sediments from the North Sea was highest in estuaries. Concentrations in sediment cores were quite stable down to the depth of background values, due to bioturbation, flow, waves and meandering channels. Terrestrial soils in Europe were highly polluted in industrial and ore mining areas and large cities. No decline in lead concentrations was evident in foraminifers, bladder wrack or fish. It was found that contamination in sediments, mammals and fish was higher in coastal zones than in the open sea. In contrast to in aquatic organisms, positive impacts of lead reduction regulations were detected in terrestrial plants, which adsorbed or took up lead mainly through atmospheric lead deposition. European lead concentrations in plants decreased coincidently with lead emissions. That trend could also be identified in the blood lead levels of the human population in Europe: since 1979 they have declined in every group of the population. Mainly influenced by age, sex and the living environment, overall, the lead loads of humans had never been high enough to cause health danger. (orig.)

  9. Fluvial deposits as an archive of early human activity: Progress during the 20 years of the Fluvial Archives Group

    Science.gov (United States)

    Chauhan, Parth R.; Bridgland, David R.; Moncel, Marie-Hélène; Antoine, Pierre; Bahain, Jean-Jacques; Briant, Rebecca; Cunha, Pedro P.; Despriée, Jackie; Limondin-Lozouet, Nicole; Locht, Jean-Luc; Martins, Antonio A.; Schreve, Danielle C.; Shaw, Andrew D.; Voinchet, Pierre; Westaway, Rob; White, Mark J.; White, Tom S.

    2017-06-01

    Fluvial sedimentary archives are important repositories for Lower and Middle Palaeolithic artefacts throughout the 'Old World', especially in Europe, where the beginning of their study coincided with the realisation that early humans were of great antiquity. Now that many river terrace sequences can be reliably dated and correlated with the globally valid marine isotope record, potentially useful patterns can be recognized in the distribution of the find-spots of the artefacts that constitute the large collections that were assembled during the years of manual gravel extraction. This paper reviews the advances during the past two decades in knowledge of hominin occupation based on artefact occurrences in fluvial contexts, in Europe, Asia and Africa. As such it is an update of a comparable review in 2007, at the end of IGCP Project no. 449, which had instigated the compilation of fluvial records from around the world during 2000-2004, under the auspices of the Fluvial Archives Group. An overarching finding is the confirmation of the well-established view that in Europe there is a demarcation between handaxe making in the west and flake-core industries in the east, although on a wider scale that pattern is undermined by the increased numbers of Lower Palaeolithic bifaces now recognized in East Asia. It is also apparent that, although it seems to have appeared at different places and at different times in the later Lower Palaeolithic, the arrival of Levallois technology as a global phenomenon was similarly timed across the area occupied by Middle Pleistocene hominins, at around 0.3 Ma.

  10. Two decades of numerical modelling to understand long term fluvial archives: Advances and future perspectives

    Science.gov (United States)

    Veldkamp, A.; Baartman, J. E. M.; Coulthard, T. J.; Maddy, D.; Schoorl, J. M.; Storms, J. E. A.; Temme, A. J. A. M.; van Balen, R.; van De Wiel, M. J.; van Gorp, W.; Viveen, W.; Westaway, R.; Whittaker, A. C.

    2017-06-01

    The development and application of numerical models to investigate fluvial sedimentary archives has increased during the last decades resulting in a sustained growth in the number of scientific publications with keywords, 'fluvial models', 'fluvial process models' and 'fluvial numerical models'. In this context we compile and review the current contributions of numerical modelling to the understanding of fluvial archives. In particular, recent advances, current limitations, previous unexpected results and future perspectives are all discussed. Numerical modelling efforts have demonstrated that fluvial systems can display non-linear behaviour with often unexpected dynamics causing significant delay, amplification, attenuation or blurring of externally controlled signals in their simulated record. Numerical simulations have also demonstrated that fluvial records can be generated by intrinsic dynamics without any change in external controls. Many other model applications demonstrate that fluvial archives, specifically of large fluvial systems, can be convincingly simulated as a function of the interplay of (palaeo) landscape properties and extrinsic climate, base level and crustal controls. All discussed models can, after some calibration, produce believable matches with real world systems suggesting that equifinality - where a given end state can be reached through many different pathways starting from different initial conditions and physical assumptions - plays an important role in fluvial records and their modelling. The overall future challenge lies in the development of new methodologies for a more independent validation of system dynamics and research strategies that allow the separation of intrinsic and extrinsic record signals using combined fieldwork and modelling.

  11. Fluvial responses to land-use changes and climatic variations within the Drury Creek watershed, southern Illinois

    Science.gov (United States)

    Miller, Suzanne Orbock; Ritter, Dale F.; Kochel, R. Craig; Miller, Jerry R.

    1993-04-01

    Fluvial responses to climatic variation and Anglo-American settlement were documented for the Drury Creek watershed, southern Illinois by examining stratigraphic, geomorphic, climatic, and historical data. Regional analyses of long-term precipitation records document a period of decreasing mean annual precipitation from 1904 to about 1945, and an increasing trend in annual precipitation from 1952 to the present. The period between 1945 and 1951 experienced a large number of intense storms that resulted in high annual precipitation totals. Statistical relationships illustrate that changes in precipitation totals are transferred to the hydrologic system as fluctuations in stream discharge. Historical records of southern Illinois show that a maximum period of settlement and deforestation occurred between the 1860s and 1920s. This era ended in the 1940s when large tracts of land were revegetated in an attempt to curtail erosion which had caused extensive upland degradation. In response to hillslope erosion at least two meters of fine-grained sediments were deposited on valley floors. Average sedimentation rates, determined using decdrochronologic techniques, are estimated to be 2.11 cm/yr for the period between 1890 and 1988; rates that are 1 to 2 orders of magnitude greater than pre-settlement values calculated for other areas of the midwest. However, botanical data suggest that aggradation was episodic, possibly occurring during three periods characterized by greater annual precipitation. Since the 1940s, sedimentation rates have declined. Reduced rates of sedimentation are related to an episode of channel entrenchment that reduced overbank flooding. Entrenchment coincided with a period of: (1) reduced sediment yields associated with watershed revegetation and the introduction of soil conservation practices, and (2) intense storm activity that resulted in long periods of high discharge. As a result of channel incision and hillslope erosion, newly exposed bedrock in

  12. Recent flow regime and sedimentological evolution of a fluvial system as the main factors controlling spatial distribution of arsenic in groundwater (Red River, Vietnam)

    DEFF Research Database (Denmark)

    Kazmierczak, J.; Larsen, F.; Jakobsen, R.

    2016-01-01

    isolating Pleistocene and Holocene aquifers were eroded, to the deep groundwater flow system discharging to Red River. Previously reported pattern of arsenic groundwater concentrations decreasing with an increasing sediment age is modified by the observed flow regime. Connection of the younger and older......We investigate a relationship between geological history, groundwater flow paths and the spatial distribution of arsenic in aquifers of the upper part of the Red River delta in Vietnam. Hydrogeological conditions in the research area are complex. The fining upward sequence of Pleistocene alluvial...... sediments was partially eroded during the Holocene and covered by sand and clay deposited in fluvial environments. Sedimentary processes lead to the development of two flow systems. Shallow groundwater discharges either to the local surface water bodies or, in the areas where low permeable sediments...

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

    Science.gov (United States)

    Beylich, Achim A.; Laute, Katja

    2014-08-01

    The timing and rate of fluvial bedload transport are of central importance within sediment budget studies and in many applications in river science and engineering. During the years 2010, 2011 and 2012 detailed field measurements with portable impact sensors as a non-invasive technique for indirectly determining fluvial bedload transport intensity were conducted in two instrumented and supply-limited drainage basin systems (Erdalen and Bødalen) in the fjord landscape in western Norway. Additional field measurements with portable impact sensors were carried out in 2010 and 2011 in selected transport-limited fluvial systems in the Coast Mountains of western Canada. The collected impact sensor field data were calibrated with laboratory flume experiments. The data from the impact sensor field measurements in western Norway and the flume experiments were combined with field data from continuous discharge monitoring, repeated surveys of channel morphometry and sediment texture, particle tracer measurements, Helley-Smith samplings, underwater video filming and biofilm analyses. The combination of methods and techniques applied provides insights into the temporal variability and intensity of fluvial bedload transport in the selected mountain streams: (i) in the transport-limited systems with generally high bedload transport rates during high discharge and with bedload material moving in clusters over the impact sensor plates, impact sensor data (based on a 1 s measuring interval) provide the opportunity to detect the start and end of bedload transport, thus to identify discharge thresholds for sediment entrainment, and to roughly estimate the intensity and relative intensity of change of bedload transport during the measuring period; (ii) in the supply-limited systems with low bedload transport rates and bedload components moving separately (as single particles) over the impact sensor plates, impact sensor data (with a 1 s measuring interval) allow the detection of the

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

    Science.gov (United States)

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

    2013-12-01

    The purpose of this work is to suggest how experiments might be constructed to provide data to test recently proposed phenomenological non-local model of depositional transport; formulated on the basis of morphological arguments but with limited data. A sound methodology for developing models of geological systems is to first collect significant data and then carefully identify an appropriate model form and parameters. An alternative approach is to construct what might be referred to as a phenomenological model, where limited observation of the system is used to suggest an appropriate mathematical form that matches the critical nature of the physical system behavior. By their nature, phenomenological models are often developed within a fairly narrow range of observations. In this way, interesting findings can occur when the models are modified and exercised across wider physical domains, in particular in domains where there is an absence of hard data to corroborate or invalidate the model predictions. Although this approach might be frown on my some, it is important to recognize the stellar and proven track record of phenomenological models, which despite the original scarcity of data, often pave the way to new perspectives and important findings. The poster child example is the Higgs boson. In the early 60's manipulation of the quantum field equations revealed a critical inconsistency related to the masses of fundamental particles that could only be mathematically resolved by assuming that they operated within a field that would exert drag; this conjecture took almost fifty years and the vast experimental operation of the Large Hadron Collider to physically confirm. In this work we examine a current phenomenological model used to describe non-local transport in fluvial sediment domains. This model has its genesis in attempting to describe the shapes of hill slope profiles, while acknowledging the fact that two points of the landscape with the same local slope are

  15. Asymmetric progradation of a coastal mangrove forest controlled by combined fluvial and marine influence, Cù Lao Dung, Vietnam

    Science.gov (United States)

    Fricke, A. T.; Nittrouer, C. A.; Ogston, A. S.; Vo-Luong, H. P.

    2017-09-01

    Mangrove forests are an important means of coastal protection along many shorelines in the tropics, and are often associated with large rivers there. Isolating the contribution of any one factor to the progradation or retreat of a coastal mangrove forest is often hindered by the physical separation between sites that are subject to vastly different combinations of marine and fluvial influence. The mangrove forest at the seaward end of Cù Lao Dung, an island in the Mekong Delta, includes areas with progradation rates of 10 s m y-1, and areas that have experienced little to no progradation in recent decades. The physical proximity (<12 km) of these two environments allows detailed hydrodynamic and sediment-dynamic measurements to be related directly to morphologic change and century-scale stratigraphy. Contrary to conventional understanding, the region of mangrove forest prograding most rapidly is subject to the greatest wave attack, while progradation is slowest in the most quiescent area. Limited progradation here is the product of a reduction in the supply of sediment to certain parts of the mangrove forest due to nearby estuarine dynamics operating on spring-neap timescales. Measurements of sediment flux show net transport into the rapidly prograding part of the forest, and transport out from the part of the forest with minimal progradation. Century-scale rates of sediment accumulation determined using 210Pb geochronology are consistent with in-situ dynamical measurements and geomorphic evolution of the mangrove forest. Where progradation is most rapid, sediment accumulation rates (3.0-5.1 cm y-1) exceed the rate of local sea-level rise (∼1.5 cm y-1). In contrast, sediment-accumulation rates in the area of minimal progradation (0.8-2.8 cm y-1) only somewhat exceed the rate of local sea-level rise, if at all. Physical stratification is well preserved in cores from areas of rapid progradation, consistent with energetic transport processes and an ample sediment

  16. History of the Federal Interagency Sedimentation Project

    Science.gov (United States)

    Skinner, John V.

    1989-01-01

    Since 1939, the date of the Project's inception, the team has operated under the direction of two lead agencies - the U.S. Geological Survey and U.S. Army Corps of Engineers. The supporting agencies are the Agricultural Research Service, Bureau of Reclamation, U.S. Forest Service, Bureau of Land Management, Federal Highway Administration, and the Tennessee Valley Authority. Overall direction of the Project rests with the Subcommittee on Sedimentation, Interagency Advisory Committee on Water Data. The Project's goals focus on improving and maintaining the quality of fluvial sediment data by (1) developing sediment samplers, laboratory analyzers, and automatic gages (2) evaluating methods, (3) standardizing equipment and methods and (4) procuring, calibrating and selling equipment.

  17. Temporal dynamics of suspended sediment transport in a glacierized Andean basin

    Science.gov (United States)

    Mao, Luca; Carrillo, Ricardo

    2017-06-01

    Suspended sediment transport can affect water quality and aquatic ecosystems, and its quantification is of the highest importance for river and watershed management. Suspended sediment concentration (SSC) and discharge were measured at two locations in the Estero Morales, a Chilean Andean stream draining a small basin (27 km2) hosting glacierized areas of about 1.8 km2. Approximately half of the suspended sediment yield (470 t year- 1 km- 2) was transported during the snowmelt period and half during glacier melting. The hysteresis patterns between discharge and SSC were calculated for each daily hydrograph and were analysed to shed light on the location and activity of different sediment sources at the basin scale. During snowmelt, an unlimited supply of fine sediments is provided in the lower and middle part of the basin and hysteresis patterns tend to be clockwise as the peaks in SSC precede the peak of discharge in daily hydrographs. Instead, during glacier melting the source of fine sediments is the proglacial area, producing counterclockwise hysteresis. It is suggested that the analysis of hysteretic patterns over time provides a simple concept for interpreting variability of location and activity of sediment sources at the basin scale.

  18. Modern analogs for the importance of seaward migration of the equilibrium point and Bayline and production of subareal accommodation space and widespread fluvial reservoirs and stratigraphic traps: Late highstand systems tracts on the broad continental margin of the East China Sea

    Energy Technology Data Exchange (ETDEWEB)

    Bartek, L.R.; Wellner, R. (Univ. of Alabama, Tuscaloosa, AL (United States))

    1996-01-01

    Geopulse seismic reflection (2,825 km) data collected during a survey of the East China Sea (ECS) in September of 1993 have been used to reconstruct the shallow stratigraphic architecture of the ECS continental margin. This area is characterized by a broad continental shelf and has extremely high sediment supply relative to other margins. On the inner to middle portions of the ECS margin we identified extensive areas outside of several incised valleys that contain channelized seismic facies that are interpreted as fluvial sequences deposited as sea level fell prior to the last low-stands. These deposits lie above highstand silts and clays and beneath a transgressive surface, above which sediments appear to have been extensively reworked. Historical records suggest that the tremendous sediment load of the Yellow River caused the river to avulse over an area of hundreds of kilometers during the Holocene and deposition of thick sheet of fluvial sands in [open quotes]interfluvial[close quotes] areas. We suggest that as sea level fall in this area, the equilibrium point and bayline synchronously migrated seaward, and subareal accommodation was created during the latter stages of highstands, in a manner similar to that proposed in published models. The high sediment supply of the area and increasing subareal accommodation space provided an opportunity for deposition of the laterally extensive fluvial facies we observe on the seismic data. The upper portions of these [open quotes]interfluvial[close quotes] fluvial deposits were reworked during the ensuing transgression and downlapped upon by muddy highstand deposits, but the lower fluvial sheet-sand facies, are preserved in place. This situation creates a laterally extensive, braided fluvial sand type reservoir with a potential for a stratigraphic seal that is within close proximity to hydrocarbon source rocks.

  19. Modern analogs for the importance of seaward migration of the equilibrium point and Bayline and production of subareal accommodation space and widespread fluvial reservoirs and stratigraphic traps: Late highstand systems tracts on the broad continental margin of the East China Sea

    Energy Technology Data Exchange (ETDEWEB)

    Bartek, L.R.; Wellner, R. [Univ. of Alabama, Tuscaloosa, AL (United States)

    1996-12-31

    Geopulse seismic reflection (2,825 km) data collected during a survey of the East China Sea (ECS) in September of 1993 have been used to reconstruct the shallow stratigraphic architecture of the ECS continental margin. This area is characterized by a broad continental shelf and has extremely high sediment supply relative to other margins. On the inner to middle portions of the ECS margin we identified extensive areas outside of several incised valleys that contain channelized seismic facies that are interpreted as fluvial sequences deposited as sea level fell prior to the last low-stands. These deposits lie above highstand silts and clays and beneath a transgressive surface, above which sediments appear to have been extensively reworked. Historical records suggest that the tremendous sediment load of the Yellow River caused the river to avulse over an area of hundreds of kilometers during the Holocene and deposition of thick sheet of fluvial sands in {open_quotes}interfluvial{close_quotes} areas. We suggest that as sea level fall in this area, the equilibrium point and bayline synchronously migrated seaward, and subareal accommodation was created during the latter stages of highstands, in a manner similar to that proposed in published models. The high sediment supply of the area and increasing subareal accommodation space provided an opportunity for deposition of the laterally extensive fluvial facies we observe on the seismic data. The upper portions of these {open_quotes}interfluvial{close_quotes} fluvial deposits were reworked during the ensuing transgression and downlapped upon by muddy highstand deposits, but the lower fluvial sheet-sand facies, are preserved in place. This situation creates a laterally extensive, braided fluvial sand type reservoir with a potential for a stratigraphic seal that is within close proximity to hydrocarbon source rocks.

  20. Fluvial archives, a valuable record of vertical crustal deformation

    Science.gov (United States)

    Demoulin, A.; Mather, A.; Whittaker, A.

    2017-06-01

    The study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms, but also for identifying the nature of crustal deformation and its history. In recent decades, geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens. Here, we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions (the effects of horizontal deformation are not addressed). Channel long profiles have received considerable attention in the literature, and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives, before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady-state characteristics. Then, we review the literature dealing with the transient response of rivers to tectonic perturbation, through the production of knickpoints propagating through the drainage network. Inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories. Finally, we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes. As well as the erosional imprint of tectonic forcing, sedimentary deposits, such as fluvial terrace staircases, are also considered as a classical component of tectonic geomorphology. We show that these studies have recently benefited from rapid advances in dating techniques, allowing more reliable reconstruction of incision histories and estimation of incision rates. The combination of progress in the understanding of transient river profiles and larger, more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace

  1. Impacts of fluvial sedimentary heterogeneities on CO2 storage performance

    Science.gov (United States)

    Issautier, B. H.; Viseur, S.; Audigane, P. D.

    2011-12-01

    The heterogeneity of fluvial systems is a key parameter in sedimentology due to the associated impacts on flow performance. In a broader context, fluvial reservoirs are now targets for CO2 storage projects in several sedimentary basins (Paris Basin, North German Basin), thus calling for detailed characterization of reservoir behaviour and capacity. Fluvial reservoirs are a complex layout of highly heterogeneous sedimentary bodies with varying connectivity, depending on the sedimentary history of the system. Reservoir characterization must determine (a) the nature and dimension of the sedimentary bodies, and (b) the connectivity drivers and their evolution throughout the stratigraphic succession. Based on reservoir characterization, geological modelling must account for this information and can be used as a predictive tool for capacity estimation. Flow simulation, however, describes the reservoir behaviour with respect to CO2 injection. The present work focuses on fluvial reservoir performance and was carried out as part of a PhD (2008-2011) dedicated to the impact of sedimentary heterogeneity on CO2 storage performance. The work comprises three steps: ? Reservoir characterization based on detailed fieldwork (sedimentology and sequence stratigraphy) carried out in Central Arabia on the Minjur Sandstone. Twelve depositional environments and their associated heterogeneity are identified, and their layout is presented in a high-resolution sequence stratigraphy analysis. This step is summed up in a 3D geological model. ? Conceptual modelling based on this field data, using gOcad software and an in-house python code. The purpose was to study, for a given architecture, the impact of sedimentary heterogeneity on storage capacity estimations using two models: one with heterogeneity within the sedimentary fill (model A); the other without heterogeneity within the sedimentary fill (model B). A workflow was designed to estimate and compare the storage capacities for a series

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

    Science.gov (United States)

    Perks, Matthew Thomas; Warburton, Jeff

    2016-09-01

    This paper describes the implementation of a novel mitigation approach and subsequent adaptive management, designed to reduce the transfer of fine sediment (scheme on the fluvial suspended sediment dynamics. Analysis of the river response demonstrates that the fluvial sediment system has become more restrictive with reduced fine sediment transfer. This is characterized by reductions in flow-weighted mean suspended sediment concentrations from 77.93 mg L-1 prior to mitigation, to 74.36 mg L-1 following the diversion. A Mann-Whitney U test found statistically significant differences (p < 0.001) between the pre- and post-monitoring median suspended sediment concentrations (SSCs). Whilst application of one-way analysis of covariance (ANCOVA) on the coefficients of sediment rating curves developed before and after the diversion found statistically significant differences (p < 0.001), with both Loga and b coefficients becoming smaller following the diversion. Non-parametric analysis indicates a reduction in residuals through time (p < 0.001), with the developed LOWESS model over-predicting sediment concentrations as the channel stabilizes. However, the channel is continuing to adjust to the reconfigured morphology, with evidence of a headward propagating knickpoint which has migrated 120 m at an exponentially decreasing rate over the last 7 years since diversion. The study demonstrates that channel reconfiguration can be effective in mitigating fine sediment flux in headwater streams but the full value of this may take many years to achieve whilst the fluvial system slowly readjusts.

  3. Basic principles and ecological consequences of changing water regimes on nitrogen cycling in fluvial systems.

    Science.gov (United States)

    Pinay, Gilles; Clément, Jean Christophe; Naiman, Robert J

    2002-10-01

    Understanding the environmental consequences of changing water regimes is a daunting challenge for both resource managers and ecologists. Balancing human demands for fresh water with the needs of the environment for water in appropriate amounts and at the appropriate times are shaping the ways by which this natural resource will be used in the future. Based on past decisions that have rendered many freshwater resources unsuitable for use, we argue that river systems have a fundamental need for appropriate amounts and timing of water to maintain their biophysical integrity. Biophysical integrity is fundamental for the formulation of future sustainable management strategies. This article addresses three basic ecological principles driving the biogeochemical cycle of nitrogen in river systems. These are (1) how the mode of nitrogen delivery affects river ecosystem functioning, (2) how increasing contact between water and soil or sediment increases nitrogen retention and processing, and (3) the role of floods and droughts as important natural events that strongly influence pathways of nitrogen cycling in fluvial systems. New challenges related to the cumulative impact of water regime change, the scale of appraisal of these impacts, and the determination of the impacts due to natural and human changes are discussed. It is suggested that cost of long-term and long-distance cumulative impacts of hydrological changes should be evaluated against short-term economic benefits to determine the real environmental costs.

  4. Evolution of ice-dammed proglacial lakes in Última Esperanza, Chile: implications from the late-glacial R1 eruption of Reclús volcano, Andean Austral Volcanic Zone Evolución de lagos proglaciales embalsados por hielo en Última Esperanza, Chile: Implicancias de la explosión volcánica tardiglacial R1 del volcán Reclús, Zona Volcánica Austral Andina

    Directory of Open Access Journals (Sweden)

    Charles R Stern

    2011-01-01

    Full Text Available Newly described outerops, excavations and sediment cores from the region of Última Esperanza, Magallanes, contain tephra derived from the large late-glacial explosive Rl eruption of the Reclús volcano in the Andean Austral Volcanic Zone. New radiocarbon dates associated to these deposits refine previous estimates of the age, to 14.9 cal kyrs BP (12,670±240 14C yrs BP, and volume, to >5 km³, of this tephra. The geographic and stratigraphic distribution of Rl also place constraints on the evolution of the ice-dammed proglacial lake that existed east of the cordillera in this area between the termination of the Last Glacial Maximum (LGM and the Holocene. This proglacial lake generated wave-cut terraces, and also caves, such as the Cueva de Milodón, along the highest prominent terrace. The current elevation of these terraces depends on the total amount of post-glacial isostatic rebound, which is unknown. Due to differential rebound, the highest prominent lake terraces decrease in height from west-to-east, from -170 m a.s.l. on Península Antonio Varas west of Seno Ultima Esperanza, to-150 m a.s.l. aroundLago Sofía, anddownto-125 m a.s.l. along their easternmost margin. The presence of thick deposits of Rl tephra in some of the caves around Lago Sofía implies that the proglacial lake had already dropped below its highest level prior to the time of this eruption, and, in fact, even earlier, prior to 16.1 cal kyrs BP (13,560±180 14C yrs BP, when land mammals first oceupied these caves. The depositional environment of Rl in a core from Dumestre bog suggests that the lake level was in fact 70 m a.s.l. until 12.8 cal kyrs BP (10,695±40 14C yrs BP. However, a 14.2 cal kyrs BP (12,125±85 14C yrs BF Mylodon pelvis from a nearby site, located at only -7 m a.s.l., suggests that the lake could have emptied, for at least a brief period, to this low level at this time. This latter datum, combined with the lack of any prominent terraces between the

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

    Science.gov (United States)

    Dearing, John; Hoffmann, Thomas

    2010-05-01

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

  6. The evolution of a colluvial hollow to a fluvial channel with periodic steps following two transformational disturbances: A wildfire and a historic flood

    Science.gov (United States)

    Rengers, Francis; McGuire, Luke; Ebel, Brian A.; Tucker, G. E.

    2018-01-01

    The transition of a colluvial hollow to a fluvial channel with discrete steps was observed after two landscape-scale disturbances. The first disturbance, a high-severity wildfire, changed the catchment hydrology to favor overland flow, which incised a colluvial hollow, creating a channel in the same location. This incised channel became armored with cobbles and boulders following repeated post-wildfire overland flow events. Three years after the fire, a record rainstorm produced regional flooding and generated sufficient fluvial erosion and sorting to produce a fluvial channel with periodically spaced steps. An analysis of the step spacing shows that after the flood, newly formed steps retained a similar spacing to the topographic roughness spacing in the original colluvial hollow (prior to channelization). This suggests that despite a distinct change in channel form roughness and bedform morphology, the endogenous roughness periodicity was conserved. Variations in sediment erodibility helped to create the emergent steps as the largest particles ( >D84) remained immobile, becoming step features, and downstream soil was easily winnowed away.

  7. Methods for determination of radioactive substances in water and fluvial sediments

    Science.gov (United States)

    Thatcher, Leland Lincoln; Janzer, Victor J.; Edwards, Kenneth W.

    1977-01-01

    Analytical methods for the determination of some of the more important components of fission or neutron activation product radioactivity and of natural radioactivity found in water are reported. The report for each analytical method includes conditions for application of the method, a summary of the method, interferences, required apparatus and reagents, analytical procedures, calculations, reporting of results, and estimation of precision. The fission product isotopes considered are cesium-137, strontium-90, and ruthenium-106. The natural radioelements and isotopes considered are uranium, lead-210, radium-226, radium-228, tritium, and carbon-14. A gross radioactivity survey method and a uranium isotope ratio method are given. When two analytical methods are in routine use for an individual isotope, both methods are reported with identification of the specific areas of application of each. Techniques for the collection and preservation of water samples to be analyzed for radioactivity are discussed.

  8. A probabilistic sediment cascade model of sediment transfer through a mountain basin

    Science.gov (United States)

    Bennett, G. L.; Molnar, P.; McArdell, B. W.; Lane, S. N.; Burlando, P.

    2013-12-01

    Mountain basin sediment discharge poses a significant hazard to the downstream population, particularly in the form of debris flows. The importance and sensitivity of snow and ice melt processes in mountain basins along with their rapid rainfall-runoff response makes mountain basin sediment discharge particularly responsive to climate change. It is important to understand and model sediment transfer through mountain basins to be able to predict sediment discharge under a changing climate. We developed a probabilistic sediment cascade model, SedCas, to simulate sediment transfer in a mountain basin (Illgraben, Switzerland) where sediment is produced by hillslope landslides and exported out of the basin by debris flows and floods. We present the model setup, the calibration of the model for the period 2000 - 2009 and the application of SedCas to model sediment discharge in the Illgraben over the 19th and 20th centuries. SedCas conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through multiple cycles of storage and remobilization by surface runoff. Sediment input is drawn from a probability distribution of slope failures produced for the basin from a time series of DEMs and the model is driven by observed climate. The model includes all relevant hydrological processes that lead to runoff in an Alpine basin, such as snow cover accumulation, snowmelt, evapotranspiration, and soil water storage. Although the processes of sediment transfer and debris flow generation are described in a simplified manner, SedCas produces highly complex sediment discharge behavior which is driven by the availability of sediment and antecedent moisture (system memory) as well as triggering potential (climate). The model reproduces the first order properties of observed debris flows over the period 2000-2009 including their probability distribution, seasonal timing and probability of

  9. A TOOLBOX FOR SEDIMENT BUDGET RESEARCH IN SMALL CATCHMENTS

    Directory of Open Access Journals (Sweden)

    S. Chalov

    2017-01-01

    Full Text Available Sediment monitoring and assessment remain one of the most challenging tasks in fluvial geomorphology and water quality studies. As a response to various environmental and human disturbance effects, the main sources and pathways of the sediments transported within catchments, especially most pristine small one, may change. The paper discusses state-of-the-art in the sediment budget research for small catchments. We identified nine independent approaches in the sediment transport assessment and applied them in 11 catchments across Eurasia in the framework of an FP – 7 Marie Curie – International Research Staff Exchange Scheme in 2012-2016. These methods were classified as: i Field-based methods (In-situ monitoring of sediment transport;– Soil morphological methods and dating techniques; Sediment source fingerprinting; Sediment-water discharge relationships, ii GIS and remote sensing approaches (Riverbed monitoring based on remote sensing/historical maps; parametrization of the channel sediment connectivity; Sediment transport remote sensing modeling, and iii Numerical approaches (Soil erosion modeling and gully erosion (stochastic and empirical models; channel hydrodynamic modeling. We present the background theory and application examples of all selected methods. Linking fieldbased methods and datasets with numerical approaches, process measurements as well as monitoring can provide enhanced insights into sediment transfer and related water quality impacts. Adopting such integrated and multi-scale approaches in a sediment budget framework might contribute to improved understanding of hydrological and geomorphological responses. 

  10. Palaeochannels (stone-rolls) in coal seams: Modern analogues from fluvial deposits of the Okavango Delta, Botswana, southern Africa

    Science.gov (United States)

    Cairncross, B.; Stanistreet, I. G.; McCarthy, T. S.; Ellery, W. N.; Ellery, K.; Grobicki, T. S. A.

    1988-05-01

    Two varieties of fluvial sandstones are associated with coal seams in the Permian Witbank Coalfield of South Africa. The first comprises lenticular channel-fill sandstone, minor conglomerate and siltstone encased entirely within the coal seam. Medium- to coarse-grained arkosic sandstones are structured by planar cross-bedding and fine upwards into carbonaceous siltstone and overlying coal. These palaeochannel-fill deposits are 5 km wide in proximal basin areas and narrow down palaeoslope to less than 1 km in width. The second variety of channel fill consists of medium- to coarse-grained sandstone which occurs below the floor of the coal seam. These deposits form undulating ridges that occur either in sub-parallel groups or as isolated shoe-string type bodies at the coal-floor rock contact. Both features are referred to as stone-rolls in colliery terminology. These ancient deposits are compared with active and abandoned fluvial systems from the Okavango Delta in Botswana, southern Africa. Active channels are flanked by extensive peat swamps which effectively confine and stabilize the channel margins. Clastic sedimentation is therefore completely confined to the channels by the vegetation and deposition occurs by vertical aggradation. Recently abandoned channels in the Okavango Delta display a variety of well preserved bed-forms which alternate with scoured depressions along the thalweg producing an undulating topography to the channel floor. These features provide a modern analogue for the stone-rolls in the coalfield deposits. The subsequent channel abandonment, vegetation encroachment and peat formation over the sand bodies would form a coal seam superimposed on the irregular surface, provided channel abandonment was followed by subsidence, overlying sediment deposition, compaction and coalification of the peat. Although the Okavango rivers are narrower and transport finer-grained sand than their Permian counterparts, the mechanism of formation and style of

  11. Assessing Sediment and Nutrient Transport in the Pra Basin of Ghana

    African Journals Online (AJOL)

    komla

    Fluvial sediment affects not only the quality of water for domestic and other purposes, but ... Control and sustainable management of watersheds are major issues in .... The bias correction factor proposed by Ferguson (1986) was applied to ... To measure the agreement between the model and the observed data, and also to ...

  12. 100-kyr fluvial fill terrace cycles since the Middle Pleistocene in the southern Central Andes, Toro Basin, NW Argentina

    Science.gov (United States)

    Tofelde, Stefanie; Schildgen, Taylor F.; Bookhagen, Bodo; Savi, Sara; Pingel, Heiko; Wickert, Andrew D.; Wittmann, Hella; Alonso, Ricardo N.; Strecker, Manfred R.

    2017-04-01

    Fluvial fill terraces in intermontane basins are valuable sedimentary and geomorphic archives that record tectonic and/or climate- driven changes of river networks and their adjacent hillslopes. However, the rarely complete preservation of such geomorphic features, often combined with large distances from sediment source areas, complicates the identification of causal links between tectonic/climatic forcing mechanisms and landscape response, especially over timescales of 105 to 106 years. The intermontane Quebrada del Toro Basin in the Eastern Cordillera of NW Argentina contains at least five fluvial terrace-surface remnants that have been sculpted into a succession of several-hundred-meter-thick Quaternary gravel conglomerate. These terraces can be followed over several tens of kilometers and are located in the higher part of the basin, close to the sediment source areas. In this study, we determined the onset of multiple river incision phases by dating the abandonment of the three most extensive and best preserved terrace surfaces with nine cosmogenic 10Be-depth profiles. The timing of terrace-gravel deposition is based on four cosmogenic 26Al/10Be burial ages and U-Pb zircon age estimates of three intercalated volcanic ashes in the conglomeratic fill. The 10Be depth profile ages suggest a successive abandonment of these terrace surfaces with a 100-kyr-cyclicity between 487 ± 34 ka and 75 ± 7 ka. Depositional ages of the conglomerates, determined by 26Al/10Be burial samples and U-Pb zircon ages, range from 936 ± 170 ka to 18 ± 141ka. They show a clear overlap with the terrace-surface abandonment ages and thus indicate the existence of multiple cut-and-fill cycles. Although the initial onset of aggradation of the Quaternary gravel conglomerate at ˜1 Ma and the overall net fluvial incision since ˜0.5 Ma can be linked to tectonic processes affecting the narrow basin outlet, the superimposed 100-kyr-cycles of aggradation and incision are best explained by

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

    Science.gov (United States)

    Viles, Heather

    2015-04-01

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

  14. Assessment of spatiotemporal variations in the fluvial wash-load component in the 21st century with regard to GCM climate change scenarios.

    Science.gov (United States)

    Mouri, Goro

    2015-11-15

    For stream water, in which a relationship exists between wash-load concentration and discharge, an estimate of fine-sediment delivery may be obtained from a traditional fluvial wash-load rating curve. Here, we demonstrate that the remaining wash-load material load can be estimated from a traditional empirical principle on a nationwide scale. The traditional technique was applied to stream water for the whole of Japan. Four typical GCMs were selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble to provide the driving fields for the following regional climate models to assess the wash-load component based on rating curves: the Model for Interdisciplinary Research on Climate (MIROC), the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), the Hadley Centre Global Environment Model (HadGEM) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model. The simulations consisted of an ensemble, including multiple physics configurations and different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5), which was used to produce monthly datasets for the whole country of Japan. The impacts of future climate changes on fluvial wash load in Japanese stream water were based on the balance of changes in hydrological factors. The annual and seasonal variations of the fluvial wash load were assessed from the result of the ensemble analysis in consideration of the Greenhouse Gas (GHG) emission scenarios. The determined results for the amount of wash load increase range from approximately 20 to 110% in the 2040s, especially along part of the Pacific Ocean and the Sea of Japan regions. In the 2090s, the amount of wash load is projected to increase by more than 50% over the whole of Japan. The assessment indicates that seasonal variation is particularly important because the rainy and typhoon seasons, which include extreme events, are the dominant seasons. Because fluvial wash-load-component turbidity

  15. Sediment Transport

    DEFF Research Database (Denmark)

    Liu, Zhou

    Flow and sediment transport are important in relation to several engineering topics, e.g. erosion around structures, backfilling of dredged channels and nearshore morphological change. The purpose of the present book is to describe both the basic hydrodynamics and the basic sediment transport...... mechanics. Chapter 1 deals with fundamentals in fluid mechanics with emphasis on bed shear stress by currents, while chapter 3 discusses wave boundary layer theory. They are both written with a view to sediment transport. Sediment transport in rivers, cross-shore and longshore are dealt with in chapters 2...

  16. The influence of fluvial reservoir architecture on geothermal energy production in Hot Sedimentary Aquifers

    NARCIS (Netherlands)

    Willems, C.J.L.

    2014-01-01

    Currently six geothermal doublets are realized in the WNB. Five of these doublets target the same Lower Cretaceous fluvial sandstone interval, the Nieuwerkerk Formation. About 40 exploration licences are granted. Many of them also have sandstones in the same fluvial interval, the Nieuwerkerk

  17. Cisterns as sediment archives in arid environments

    Science.gov (United States)

    Junge, Andrea; Shahack-Gross, Ruth; Lomax, Johanna; Finkelstein, Israel; Fuchs, Markus

    2017-04-01

    Ancient cisterns are frequently occurring archaeological structures in semiarid, arid and hyperarid regions. These systems to collect and store water were constructed to enable the establishment of settlements, livestock farming and agricultural activity even under dry conditions. During precipitation events surface runoff from adjoining slopes erodes and transports sediments, which then can be deposited in the cistern. Therefore, these archaeological structures serve also as sediment traps and represent the fluvial processes of the cistern's catchment. Additionally, the cisterns are usually constructed to prevent any water outlet, resulting in an undisturbed, often continuous sediment record. Crucial for investigating cisterns and their sediments is the establishment of robust chronologies, with optical stimulated luminescence (OSL) dating as the preferred dating method. This enables to determine the time of construction, utilisation and abandonment of the cistern. In addition, the sediment record within the cistern represents an archive including numerous environmental proxies (e. g. pollen), which can be used for palaeoenvironmental reconstruction, serving as an important paleoenvironmental archive in dryland areas, where continuous sediment records are rare.

  18. Coupling climate conditions, sediment sources and sediment transport in an alpine basin

    Science.gov (United States)

    Rainato, Riccardo; Picco, Lorenzo; Cavalli, Marco; Mao, Luca; Neverman, Andrew J.; Tarolli, Paolo

    2017-04-01

    In a fluvial system, mountain basins control sediment export to the lowland rivers. Hence, the analysis of the erosion processes and sediment delivery patterns that act in mountain basins is important. Several studies have investigated the alterations triggered by recent climatic change on the hydrological regime, whilst only a few works have explored the consequences on the sediment dynamics. Here we combined and analyzed the quasi-unique dataset of climatic conditions, landscape response, and sediment export produced, since 1986 in the Rio Cordon basin (5 km2, Eastern Italian Alps) to examine the sediment delivery processes occurring in the last three decades. The temperature, precipitation, and fluvial sediment fluxes in the basin were analyzed using continuous measurement executed by a permanent monitoring station, while the landscape evolution was investigated by three sediment source inventories established in 1994, 2006, and 2016. Thus, the analysis focused on the trends exhibited during the periods 1986-1993, 1994-2006, and 2007-2015. In terms of climatic conditions, three distinct climate forcing stages can be observed in the periods analyzed: a relatively stable phase (1986-1993), a period characterized by temperature and rainfall fluctuations (1994-2006), and a more recent warmer and wetter phase (2007-2015). In the 1986-1993 period, the fluvial sediment fluxes reflected the stable trend exhibited by the climatic conditions. In the subsequent 1994-2006 period, the average temperature and precipitation were in line with that previously observed, although with higher interannual variability. Notwithstanding the climate forcing and the occurrence of high magnitude/low frequency floods that strongly influenced the source areas, between 1994 and 2006 the Rio Cordon basin showed relatively limited erosion activity. Hence, the climatic conditions and the landscape response can only partially explain the strong increase of sediment export recorded in the 1994

  19. Release of PCBs from Silvretta glacier (Switzerland) investigated in lake sediments and meltwater.

    Science.gov (United States)

    Pavlova, P A; Zennegg, M; Anselmetti, F S; Schmid, P; Bogdal, C; Steinlin, C; Jäggi, M; Schwikowski, M

    2016-06-01

    This study is part of our investigations about the release of persistent organic pollutants from melting Alpine glaciers and the relevance of the glaciers as secondary sources of legacy pollutants. Here, we studied the melt-related release of polychlorinated biphenyls (PCBs) in proglacial lakes and glacier streams of the catchment of the Silvretta glacier, located in the Swiss Alps. To explore a spatial and temporal distribution of chemicals in glacier melt, we combined two approaches: (1) analysing a sediment record as an archive of past remobilization and (2) passive water sampling to capture the current release of PCBs during melt period. In addition, we determined PCBs in a non-glacier-fed stream as a reference for the background pollutant level in the area. The PCBs in the sediment core from the Silvretta lake generally complied with trends of PCB emissions into the environment. Elevated concentrations during the most recent ten years, comparable in level with times of the highest atmospheric input, were attributed to accelerated melting of the glacier. This interpretation is supported by the detected PCB fractionation pattern towards heavier, less volatile congeners, and by increased activity concentrations of the radioactive tracer (137)Cs in this part of the sediment core. In contrast, PCB concentrations were not elevated in the stream water, since no significant difference between pollutant concentrations in the glacier-fed and the non-glacier-fed streams was detected. In stream water, no current decrease of the PCBs with distance from the glacier was observed. Thus, according to our data, an influence of PCBs release due to accelerated glacier melt was only detected in the proglacial lake, but not in the other compartments of the Silvretta catchment.

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

    Science.gov (United States)

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

    2015-04-01

    . In contrast, river sediment in the downstream is an erosion agent eroding the concave bank laterally, but also depositing on the concave side and protecting the bank from erosion. Finally, the results also showed that the integration of fluvial erosion factors can improve the performance in predicting landsliding along meandering rivers.

  1. Late Quaternary fluvial terrace development and changing landscape connectivity in the Great Karoo, South Africa.

    Science.gov (United States)

    Oldknow, Chris; Hooke, Janet

    2017-04-01

    Dendritic channel networks in the Wilgerbosch River catchment draining the south side of the Sneeuberg, South Africa are deeply incised exposing terrace fills of varying thickness and extent. Channel long sections exhibit 'stepped' profiles where resistant rock strata cross valley floors, but are now partially or completely breached. Using a combination of aerial image analyses, geomorphological mapping, sedimentological investigations (field logging, grain size and mineral magnetic analysis) and geochronology (OSL, radiocarbon), this presentation demonstrates the patterns and controls on erosion and sedimentation and to a lesser extent, the age structure of fills in two low-order tributaries (Africanders Kloof and Wilgerbosch Kloof) and several reaches of the higher-order Wilgerbosch River. A conceptual model of terrace development in relation to changing conditions of connectivity was tested. Valley headwaters are dominated by discontinuous palaeochannel and floodout sediments, whilst in 2nd-4th order tributaries, five sedimentologically and stratigraphically distinct terrace fills that exceed the scale and complexity of deposits to the north of the Sneeuberg, were identified and analysed. The early part of this regional terrace succession highlights the importance of interactions between periglacial and fluvial activity on cut, fill and pedogenesis in the deglacial period. Terrace development is shown to have been a complex response to re-connection of the channel network with upland colluvial stores resulting in the valleys becoming choked with sediment. This caused a rise in groundwater and formation of extensive calcretised rootmats on valley floors and slopes acting to 'blanket' terraces 1 and 2. The thickness and longevity of this blanket is shown to restrict depth of incision in subsequent phases (T3, T4). As a result, the stratigraphic record is spatially and temporally biased toward the late Pleistocene and Holocene terraces (1, 2 and 4 respectively

  2. Applications of structure-from-motion photogrammetry to fluvial geomorphology

    Science.gov (United States)

    Dietrich, James Thomas

    Since 2011, Structure-from-Motion Multi-View Stereo Photogrammetry (SfM or SfM-MVS) has gone from an overlooked computer vision technique to an emerging methodology for collecting low-cost, high spatial resolution three-dimensional data for topographic or surface modeling in many academic fields. This dissertation examines the applications of SfM to the field of fluvial geomorphology. My research objectives for this dissertation were to determine the error and uncertainty that are inherent in SfM datasets, the use of SfM to map and monitor geomorphic change in a small river restoration project, and the use of SfM to map and extract data to examine multi-scale geomorphic patterns for 32 kilometers of the Middle Fork John Day River. SfM provides extremely consistent results, although there are systematic errors that result from certain survey patterns that need to be accounted for in future applications. Monitoring change on small restoration stream channels with SfM gave a more complete spatial perspective than traditional cross sections on small-scale geomorphic change. Helicopter-based SfM was an excellent platform for low-cost, large scale fluvial remote sensing, and the data extracted from the imagery provided multi-scalar perspectives of downstream patterns of channel morphology. This dissertation makes many recommendations for better and more efficient SfM surveys at all of the spatial scales surveyed. By implementing the improvements laid out here and by other authors, SfM will be a powerful tool that will make 3D data collection more accessible to the wider geomorphic community.

  3. Formation of topographically inverted fluvial deposits on Earth and Mars

    Science.gov (United States)

    Hayden, A.; Lamb, M. P.; Fischer, W. W.; Ewing, R. C.; McElroy, B. J.

    2016-12-01

    Sinuous ridges interpreted as exhumed river deposits (so-called "inverted channels") are common features on Mars that show promise for quantifying ancient martian surface hydrology. Morphological similarity of these inverted channels to river channels led to a "landscape inversion hypothesis" in which the geometries of ridges and ridge networks accurately reflect the geometries of the paleo-river channels and networks. An alternative "deposit inversion hypothesis" proposes that ridges represent eroded fluvial channel-belt deposits with channel-body geometries that may differ significantly from those of the rivers that built the deposit. To investigate these hypotheses we studied the sedimentology and morphology of inverted channels in Jurassic and Cretaceous outcrops in Utah and the Aeolis Dorsa region of Mars. Ridges in Utah extend for hundreds of meters, are tens of meters wide, and stand up to 30 meters above the surrounding plain. A thick ribbon-geometry sandstone or conglomerate body caps overbank mudstone, paleosols, and thin crevasse-splay sandstone beds. Caprock beds consist of stacked dune- to bar-scale trough cross sets, mud intraclasts, and in cases scroll bars indicating meandering. In plan view, ridge networks bifurcate; however, crosscutting relationships show that distinct sandstone channel bodies at distinct stratigraphic levels intersect at these junctions. Ridge-forming sandstone bodies have been narrowed from their original dimensions by cliff retreat and bisected by modern fluvial erosion and mass wasting. We therefore interpret the sinuous ridges in Utah as eroded remnants of channel-belt sandstone bodies formed by laterally migrating and avulsing rivers rather than channel fills - consistent with deposit inversion. If the sinuous ridges in Aeolis Dorsa also formed by deposit inversion, river widths previously interpreted under the landscape inversion hypothesis are overestimated by up to a factor of 10 and discharges by up to a factor of 100.

  4. Tests of ground-penetrating radar and induced polarization for mapping fluvial mine tailings on the floor of the Couer d'Alene River, Idaho

    Science.gov (United States)

    Campbell, David L.; Wynn, Jefferey C.; Box, Stephen E.; Bookstrom, Arthur A.; Horton, Robert J.

    1997-01-01

    In order to investigate sequences of toxic mine tailings that have settled in the bed of the Coeur d'Alene River, Idaho, (see figure 1) we improvised ways to make geophysical measurements on the river floor. To make ground penetrating radar (GPR) profiles, we mounted borehole antennas on a skid that was towed along the river bottom. To make induced polarization (IP) profiles, we devised a bottom streamer from a garden hose, lead strips, PVC standoffs, and insulated wire. Each approach worked and provided uniquely different information about the buried toxic sediments. GPR showed shallow stratigraphy, but did not directly detect the presence of contaminating metals. IP showed a zone of high chargeability that is probably due to pockets of relatively higher metal content. Neither method was able to define the base of the fluvial tailings section, at least in part because the IP streamer was deliberately designed to sample only the top three meters of sediments to maximize horizontal resolution.

  5. The analysis of remote sensing data to delineate landsystem tracts in proglacial valleys in the Río Santa Basin, Cordillera Blanca, Perú

    Science.gov (United States)

    Narro Perez, R. A.; Eyles, C.

    2016-12-01

    The Río Santa Basin is an important glacially-influenced basin of social, economic and cultural importance to the country of Perú. It produces a large portion of Peru's hydroelectricity, is an important agricultural area, and hosts two major mining complexes. The Río Santa receives its water from precipitation, glacial runoff from over 450 glaciers draining the Cordillera Blanca, and groundwater discharge. Despite being the largest tropical glacier ice field in the world, the area of glacial coverage in the Cordillera Blanca has decreased from 825 km2 in 1930 to 528 km2 in 2003. It is estimated that glacial runoff contributes 10-20% of the Río Santa's annual flow but during the dry season it can contribute up to 66% of water flow with groundwater supplying the remainder. The contribution of glacial meltwater makes the Río Santa less susceptible to discharge variability caused by inter-annual variation in precipitation. Due to decreased meltwater contributions, the urban centers and rural communities in the basin are expected to face severe water scarcity in the future, especially during the dry season. This poster will show the results of a remote sensing survey, using Google Earth and LiDAR data, to delineate landsystem tracts and components in several proglacial valleys in the Cordillera Blanca. The results of this survey allow detailed documentation of the geomorphological evolution of the landscape which will in turn allow a better understanding of the glacial history and subsurface geology of the area. These findings will better inform current hydrogeological models used to determine the sustainability of water resources in the Río Santa basin. Understanding the landsystem architecture, sedimentology and subsurface stratigraphy of the basin will also allow these models to more accurately predict the impact that future climate change will have on water resources and the people of the Río Santa basin.

  6. Sediment carbon fate in phreatic karst (Part 1): Conceptual model development

    Science.gov (United States)

    Husic, A.; Fox, J.; Agouridis, C.; Currens, J.; Ford, W.; Taylor, C.

    2017-06-01

    Recent research has paid increased attention to quantifying the fate of carbon pools within fluvial networks, but few, if any, studies consider the fate of sediment organic carbon in fluviokarst systems despite that karst landscapes cover 12% of the earth's land surface. The authors develop a conceptual model of sediment carbon fate in karst terrain with specific emphasis upon phreatic karst conduits, i.e., those located below the groundwater table that have the potential to trap surface-derived sediment and turnover carbon. To assist with their conceptual model development, the authors study a phreatic system and apply a mixture of methods traditional and novel to karst studies, including electrical resistivity imaging, well drilling, instantaneous velocimetry, dye tracing, stage recording, discrete and continuous sediment and water quality sampling, and elemental and stable carbon isotope fingerprinting. Results show that the sediment transport carrying capacity of the phreatic karst water is orders of magnitude less than surface streams during storm-activated periods promoting deposition of fine sediments in the phreatic karst. However, the sediment transport carrying capacity is sustained long after the hydrologic event has ended leading to sediment resuspension and prolonged transport. The surficial fine grained laminae occurs in the subsurface karst system; but unlike surface streams, the light-limited conditions of the subsurface karst promotes constant heterotrophy leading to carbon turnover. The coupling of the hydrological processes leads to a conceptual model that frames phreatic karst as a biologically active conveyor of sediment carbon that recharges degraded organic carbon back to surface streams. For example, fluvial sediment is estimated to lose 30% of its organic carbon by mass during a one year temporary residence within the phreatic karst. It is recommended that scientists consider karst pathways when attempting to estimate organic matter stocks

  7. Time-transgressive tunnel valley formation indicated by infill sediment structure, North Sea - the role of glaciohydraulic supercooling

    DEFF Research Database (Denmark)

    Kristensen, Thomas Bojer; Piotrowski, Jan; Huuse, Mads

    2008-01-01

    , the volumetrically most important and structurally most distinct, is composed of clinoform reflections downlapping axially up-valley (up-ice), Facies II is composed of near-horizontal, continuous and well layered reflections onlapping the clinoform reflections and the valley walls and Facies III is composed...... of clinoform reflections downlapping axially down-valley (down-ice). A model of formation of this sediment architecture is proposed, in which valley incision and infill are causally linked. It is proposed that Facies I is related to glaciohydraulic supercooling of subglacial meltwater in the distal parts...... of tunnel valleys. The valleys formed time-transgressively during ice retreat, whereby sediment eroded further up-ice was re-deposited along adverse subglacial slopes of the valleys close to the ice margin. The formation of Facies II and III is related to the deposition in proglacial basins during final...

  8. Microbial biomass and activity in subsurface sediments from Vejen, Denmark

    DEFF Research Database (Denmark)

    Albrechtsen, Hans-Jørgen; Winding, Anne

    1992-01-01

    Subsurface sediment samples were collected from 4 to 31 m below landsurface in glacio-fluvial sediments from the Quaternary period. The samples were described in terms of pH, electrical conductivity, chloride concentration, organic matter content, and grain size distribution. Viable counts......, AODC increased and the mineralization rate declined. Intrinsic permeability calculated from grain size correlated positively with mineralization rate for acetate. Statistical correlation analysis showed high correlations between some of the abiotic parameters, but it was not possible to point out...... a single abiotic parameter that could explain the variation of size and activity of the microbial population. The microbial data obtained in these geologically young sediments were compared to literature data from older sediments, and this comparison showed that age and type of geological formation might...

  9. Tidal-fluvial interaction in the Guadalquivir River Estuary: Spatial and frequency-dependent response of currents and water levels

    Science.gov (United States)

    Losada, M. A.; Díez-Minguito, M.; Reyes-Merlo, M. Á.

    2017-02-01

    This paper presents a study on the tidal-fluvial interaction in the highly regulated Guadalquivir River Estuary (SW Spain), which is occasionally subjected to high discharge episodes that affect navigational conditions and increase flood risks. The study specifically focuses on the processes and controlling mechanisms of the nonstationary response of water levels and currents to high discharges. Measurements show a 60 day postdischarge amplification of tidal current and elevation amplitudes and a clockwise rotation of the tidal ellipse in the upper layers. A decrease of amplitudes and an anticlockwise rotation predominate near the bed. Such episodes significantly increase the tidal wave celerity, and especially at high and low water. These features are due to the suspended sediment stratification triggered by the discharge event. The increase in stratification restricts frictional influence to bottom layers, partially decoupling the overlying flow from the bottom. A nonstationary harmonic decomposition method, intended for identifying which nonlinear terms in the governing hydrodynamic equations control overtide and compound tide generation, shows that quadratic bottom stress contributes the most during high discharge periods. The consequence in the subtidal balance is that, during peak discharge and in the upper stretches, friction is largely balanced by the water level gradient, although the density gradient term becomes comparable to the friction term soon after peak discharge. Advection is also important to the force balance in the lower estuary. For both parts, to correctly explain subtidal dynamics, it is necessary to account for the time variability of the friction coefficient due to flow-sediment feedback.

  10. Morphology of fluvial levee series along a river under human influence, Maros River, Hungary

    Science.gov (United States)

    Kiss, Tímea; Balogh, Márton; Fiala, Károly; Sipos, György

    2018-02-01

    The development and morphometry of fluvial levees reflect the connection between channel and overbank processes, which can be altered by various human activities. The aims of this study are to investigate the morphology and spatial characteristics of fluvial levees and evaluate the role of some local- and catchment-scale human activities on their medium-term (150 years) development. This study applies LiDAR data along a 53-km-long reach of the Maros River in Hungary. Six fluvial levee types are identified based on the beginning and end of their evolution. These levee types were generated by local nineteenth century channel regulation works (cutoffs) and mid-twentieth century channel narrowing, which was caused by gravel mining and water impoundment in the upstream sections. However, other human activities also influenced the development of active fluvial levees because their horizontal evolution could have been limited by embanked flood-protection levees or the widening of low-lying floodplain benches that were generated by channel narrowing. Additionally, revetment constructions influenced their vertical parameters as higher fluvial levees developed along the fixed banks. Generally, the older active fluvial levees are wider, while the younger active levees are narrower with steeper slopes but not always lower. On the low-lying floodplain levels (benches), the youngest fluvial levees evolved quite rapidly and consist of coarser material. Currently, only 9.8- to 38-year return-period floods could cover the fluvial levees, contributing to their evolution. This fact and the development of fluvial levee series with two-three members reflect a gradual decoupling of the channel from the floodplain.

  11. Concentrations of selected metals in Quaternary-age fluvial deposits along the lower Cheyenne and middle Belle Fourche Rivers, western South Dakota, 2009-10

    Science.gov (United States)

    Stamm, John F.; Hoogestraat, Galen K.

    2012-01-01

    The headwaters of the Cheyenne and Belle Fourche Rivers drain the Black Hills of South Dakota and Wyoming, an area that has been affected by mining and ore-milling operations since the discovery of gold in 1875. A tributary to the Belle Fourche River is Whitewood Creek, which drains the area of the Homestake Mine, a gold mine that operated from 1876 to 2001. Tailings discharged into Whitewood Creek contained arsenopyrite, an arsenic-rich variety of pyrite associated with gold ore, and mercury used as an amalgam during the gold-extraction process. Approximately 18 percent of the tailings that were discharged remain in fluvial deposits on the flood plain along Whitewood Creek, and approximately 25 percent remain in fluvial deposits on the flood plain along the Belle Fourche River, downstream from Whitewood Creek. In 1983, a 29-kilometer (18-mile) reach of Whitewood Creek and the adjacent flood plain was included in the U.S. Environmental Protection Agency's National Priority List of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, commonly referred to as a "Superfund site." Listing of this reach of Whitewood Creek was primarily in response to arsenic toxicity of fluvial deposits on the flood plain. Lands along the lower Cheyenne River were transferred to adjoining States and Tribes in response to the Water Resources Development Act (WRDA) of 1999. An amendment in 2000 to WRDA required a study of sediment contamination of the Cheyenne River. In response to the WRDA amendment, the U.S. Geological Survey completed field sampling of reference sites (not affected by mine-tailing disposal) along the lower Belle Fourche and lower Cheyenne Rivers. Reference sites were located on stream terraces that were elevated well above historical stream stages to ensure no contamination from historical mining activity. Sampling of potentially contaminated sites was performed on transects of the active flood plain and adjacent terraces that could

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

    Science.gov (United States)

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

    2009-12-01

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

  13. Sediment carbon fate in phreatic karst (Part 2): Numerical model development and application

    Science.gov (United States)

    Husic, A.; Fox, J.; Ford, W.; Agouridis, C.; Currens, J.; Taylor, C.

    2017-06-01

    The authors develop a numerical model to elucidate time-distributed processes controlling sediment carbon fate in phreatic karst. Sediment carbon processes simulated in the new numerical model include in-conduit erosion and deposition, sediment carbon transport, surficial fine grained laminae evolution, carbon pool mixing, microbial oxidation, and the understudied process of sediment carbon exchange during equilibrium transport. The authors perform a model evaluation procedure that includes generalized likelihood uncertainty estimation to quantify uncertainty of the model results. Modeling results suggest that phreatic karst conduits sustain sediment transport activity long after surface storm events cease. The sustained sediment transport has the potential to shift the baseflow sediment yield of the phreatic karst to be on par with stormflow sediment yield. The sustained activity is suggested to promote the exchange of sediment carbon between the water column and subsurface karst deposits during equilibrium sediment transport conditions. In turn, the sediment carbon exchange impacts the mixing of new and old carbon pools and the flux of carbon from phreatic karst. Integrated numerical model results from this study support the concept that phreatic karst act as a biologically active conveyor of sediment carbon that temporarily stores sediment, turns over carbon at higher rates than surface streams, and recharges degraded carbon back to the fluvial system. The numerical modeling method adopted in this paper shows the efficacy of coupling carbon isotope fingerprinting with water quality modeling to study sediment carbon in phreatic karst.

  14. Decoding the Morphological Differences between Himalayan Glacial and Fluvial Landscapes Using Multifractal Analysis.

    Science.gov (United States)

    Dutta, Srimonti

    2017-09-08

    Himalayas is the home to nearly 10,000 glaciers which are mostly located at high and inaccessible region. Digital Elevation Model (DEM) can be effective in the study of these glaciers. This paper aims at providing an automated distinction of glacial and fluvial morphologies using multifractal technique. We have studied the variation of elevation profile of Glacial and Fluvial landscapes using Multifractal Detrended Fluctuation Analysis (MFDFA). Glacial landscapes reveal more complex structure compared to the fluvial landscapes as indicated by fractal parameters degree of multifractality, asymmetry index.

  15. Sediment Acoustics

    National Research Council Canada - National Science Library

    Stoll, R

    2001-01-01

    ... variables such as porosity and grain-size distribution. The model is based on the classical Biot theory extended to take into account various mechanisms of energy loss that are known to be important in marine sediments...

  16. Visual Sedimentation

    OpenAIRE

    Huron, Samuel; Vuillemot, Romain; Fekete, Jean-Daniel

    2013-01-01

    International audience; We introduce Visual Sedimentation, a novel design metaphor for visualizing data streams directly inspired by the physical process of sedimentation. Visualizing data streams (e. g., Tweets, RSS, Emails) is challenging as incoming data arrive at unpredictable rates and have to remain readable. For data streams, clearly expressing chronological order while avoiding clutter, and keeping aging data visible, are important. The metaphor is drawn from the real-world sedimentat...

  17. Sedimentology and ichnology of the fluvial reach to inner estuary of the Ogeechee River estuary, Georgia, USA

    Science.gov (United States)

    Shchepetkina, Alina; Gingras, Murray K.; Pemberton, S. George

    2016-08-01

    Through the integration of sedimentological and ichnological observations, this paper explores the character of sediments deposited across the fluvio-tidal transition zone of the upper microtidal, mixed-energy, sand-dominated Ogeechee River estuary, Georgia, USA. A transect of tidally influenced to fluvial channel-bars and their facies variability is reported. Field and laboratory methods were employed, including observation of physical and biogenic sedimentary structures on the point-bar surfaces and in trenches, collection of grab samples, suction and box coring, grain size and total organic carbon analyses, optical microscopy, core logging, and daylight photography. The data presented in the paper can help in predicting facies changes across the fluvio-tidal transition of sand-dominated fluvio-tidal deposits in the rock record. The lower inner estuary is characterized by medium-fine and fine-medium sand with planar and trough cross-bedding, small-scale ripple lamination, tidal sedimentary structures (flaser and wavy bedding, herringbone cross-stratification), abundant organic debris, and mud rip-up clasts. Bioturbation of the intertidal point bars is low, but cryptobioturbation is locally observed. Upper inner estuary deposits comprise coarse-medium- and medium-coarse-grained sand, and are characterized by faint high-angle planar and trough cross-bedding. Organic debris, mud rip-up clasts, herringbone and current-ripple lamination are rarely observed. Bioturbation is absent to sparse. The fluvio-tidal transition is represented by very-coarse- to coarse-grained sand and granules. Physical sedimentary structures constitute massive, graded planar and trough cross-bedding with abundant plant detritus. Except for rare Siphonichnus- and Lockeia-like traces, bioturbation is absent. The fluvial setting is characterized by coarse-medium sand with unidirectional cross-bedding, current-ripple lamination, and rare organic-rich mud clasts. Bioturbation is absent. Inner

  18. Spatial variations in fluvial incision across the eastern margin of Tibet reveal locus of deformation in the deep crust

    Science.gov (United States)

    Kirby, Eric

    2017-04-01

    The manifestation of coupling among climate, erosion and tectonics along steep topographic margins of orogenic plateaus is strongly dependent on the processes driving crustal thickening. Along the eastern margin of the Tibetan Plateau, a long-standing and vigorous debate persists over whether mountain building occurred largely along upper-crustal faults or was the consequence of distributed thickening in the lower crust. Here I revisit this debate and show how surface deformation recorded by geomorphology over millennial timescales (10^4-105 yr) can yield insight into the role the deep crust along plateau margins. In contrast to the intensively studied Longmen Shan, the topographic margin of the Tibetan Plateau north of the Sichuan Basin follows the north-south Min Shan and cuts orthogonally across the structural grain of the Mesozoic West Qinling orogen. The lack of a direct association of topography with upper crustal faults affords an opportunity to evaluate the patterns of differential rock uplift from geomorphology. First, I employ an empirical calibration of river profile steepness (channel gradient normalized for drainage basin area) and erosion rate from cosmogenic 10Be concentrations in modern sediment. Application to the channels draining the plateau margin reveals a locus of high (300-500 m/Myr) erosion rate coincident with the Min Shan. Second, I present new results of surveying and dating of fluvial terraces developed along the Bailong Jiang, one of the major rivers draining across the plateau margin. A preliminary chronology of terrace formation and abandonment based on radiocarbon and OSL dating of fluvial deposits reveals systematic spatial gradients in fluvial incision, with highest incision rates (1000-2000 m/Myr) localized along the axis of the Min Shan and decreasing toward both the foreland and the plateau. This locus of incision has apparently been sustained through multiple generations of terrace formation and abandonment since at least 80 ka

  19. Evidences of Neotectonic Movements Recorded in Fluvial and Lacustrine Deposits of the Niger River in Bamako, Mali

    Science.gov (United States)

    Dembele, N. D. J.

    2015-12-01

    Two alluvial profiles showing evidences of tectonic movements were discovered along the right bank of the Niger River at Bamako. The first profile of 25 meters thick is composed of a laminated silt layer of about 22 meters, of a gray sand layer of 25 cm and a pebble layer of 2 meters. A layer of 80 cm wide, an intrusive body, crosscuts the silt layers. The Grain size and heavy minerals analysis showed that this vertical layer is different in structure, texture and composition from the other layers. The second profile of about 20 meters is composed of interbedded fluvial gravel and sand deposits. The tectonic evidences found on those layers are of three types: faults and fractures, folds and the intrusion between silts deposits of the sand layers previously presented. The faults and fractures are located mainly on the fluvial gravel and sand deposits, whereas the silts deposits are folded and show some microfaults. The intrusion of a sand layer between the silt layer is a geological process that is not yet well understood but it is believed that this phenomena occurs during earthquakes as the sand layer during such event behave as a liquid. The discovery of such layer testifies that earthquakes used to happen in the area. As they concern only the alluvial deposits, their age should be no more than the Quaternary period. The presence of such tectonic evidences is surprising as Bamako like all the Republic of Mali is located on the west African craton that is supposed to be tectonically stable and their occurrence on Quaternary unconsolidated sediments shows that tectonic movements used to occur on that area during the last 2 millions years or may be less whereas people continue to build houses and other social infrastructures on them without any caution.

  20. Evolution of ice-dammed proglacial lakes in Última Esperanza, Chile: implications from the late-glacial R1 eruption of Reclús volcano, Andean Austral Volcanic Zone Evolución de lagos proglaciales embalsados por hielo en Última Esperanza, Chile: Implicancias de la explosión volcánica tardiglacial R1 del volcán Reclús, Zona Volcánica Austral Andina

    National Research Council Canada - National Science Library

    Charles R Stern; Patricio I Moreno; Rodrigo Villa-Martínez; Esteban A Sagredo; Alfredo Prieto; Rafael Labarca

    2011-01-01

    .... The geographic and stratigraphic distribution of Rl also place constraints on the evolution of the ice-dammed proglacial lake that existed east of the cordillera in this area between the termination...

  1. Controls on flood and sediment wave propagation

    Science.gov (United States)

    Bakker, Maarten; Lane, Stuart N.; Costa, Anna; Molnar, Peter

    2015-04-01

    The understanding of flood wave propagation - celerity and transformation - through a fluvial system is of generic importance for flood forecasting/mitigation. In association with flood wave propagation, sediment wave propagation may induce local erosion and sedimentation, which will affect infrastructure and riparian natural habitats. Through analysing flood and sediment wave propagation, we gain insight in temporal changes in transport capacity (the flood wave) and sediment availability and transport (the sediment wave) along the river channel. Heidel (1956) was amongst the first to discuss the progressive lag of sediment concentration behind the corresponding flood wave based on field measurements. Since then this type of hysteresis has been characterized in a number of studies, but these were often based on limited amount of floods and measurement sites, giving insufficient insight into associated forcing mechanisms. Here, as part of a project concerned with the hydrological and geomorphic forcing of sediment transfer processes in alpine environments, we model the downstream propagation of short duration, high frequency releases of water and sediment (purges) from a flow intake in the Borgne d'Arolla River in south-west Switzerland. A total of >50 events were measured at 1 minute time intervals using pressure transducers and turbidity probes at a number of sites along the river. We show that flood and sediment wave propagation can be well represented through simple convection diffusion models. The models are calibrated/validated to describe the set of measured waves and used to explain the observed variation in wave celerity and diffusion. In addition we explore the effects of controlling factors including initial flow depth, flood height, flood duration, bed roughness, bed slope and initial sediment concentration, on the wave propagation processes. We show that the effects of forcing mechanisms on flood and sediment wave propagation will lead to different

  2. Implications of (reworked) aeolian sediments and paleosols for Holocene environmental change in Western Mongolia

    Science.gov (United States)

    Klinge, Michael; Lehmkuhl, Frank; Schulte, Philipp; Hülle, Daniela; Nottebaum, Veit

    2017-09-01

    In the semi-arid to semi-humid regions of western Mongolia four different geomorphological aeolian and fluvial archives were investigated in order to gain environmental information of landscape evolution during the late glacial and the Holocene. These archives, which contain aeolian deposits, fluvial sediments, and paleosols, are situated upon glacial moraines, fluvial terraces, floodplains, or mountain slopes. While radiometric dating provides information about the age of the sediment and paleosols, grain size and element distribution provide information about the sediment source and soil development. Extensive aeolian sediment transport occurred from 17 to 10 ka during the late glacial when climate was cold and dry. Since that period the developing steppe and alpine meadow vegetation served as a dust trap. During the warm and wet early to mid-Holocene sediment transport was reduced under a dense vegetation cover. All paleosols of the investigated archives show late Holocene ages which point to an environmental turning point around 3 ka. Since then, the Neoglacial period started with cooler climate conditions and periglacial processes intensified again. Recognizable glacier advances occurred during the Little Ice Age several centuries ago. Since then, global climate change leads to warmer and more arid conditions. During the late Holocene, a new period of strong geomorphological activity started and huge quantities of aeolian, colluvial and fluvial sediment accumulated. These intensified soil relocation processes cannot be explained exclusively by climate change because there are no explicit indications found in the palynological and lacustrine records of Mongolia. This discrepancy suggests that the additional factor of human impact has to be considered, which amplified the climate signal on the landscape. Simultaneously, when the enhanced geomorphological processes occurred, the prehistoric people changed from hunting and gathering to livestock husbandry. A first

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

    Science.gov (United States)

    Perks, M. T.; Warburton, J.

    2015-10-01

    This paper describes the implementation of a novel mitigation approach and subsequent adaptive management, designed to reduce the transfer of fine sediment in Glaisdale Beck; a small upland catchment in the UK. Hydro-meteorological and suspended sediment datasets are collected over a two year period spanning pre- and post-diversion periods in order to assess the impact of the channel reconfiguration scheme on the fluvial suspended sediment dynamics. Analysis of the river response demonstrates that the fluvial sediment system has become more restrictive with reduced fine sediment transfer. This is characterised by reductions in flow-weighted mean suspended sediment concentrations from 77.93 mg L-1 prior to mitigation, to 74.36 mg L-1 following the diversion. A Mann-Whitney U test found statistically significant differences (p < 0.001) between the pre- and post-monitoring median SSCs. Whilst application of one-way analysis of covariance (ANCOVA) on the coefficients of sediment rating curves developed before and after the diversion found statistically significant differences (p < 0.001), with both Log a and b coefficients becoming smaller following the diversion. Non-parametric analysis indicates a reduction in residuals through time (p < 0.001), with the developed LOWESS model over-predicting sediment concentrations as the channel stabilises. However, the channel is continuing to adjust to the reconfigured morphology, with evidence of a headward propagating knickpoint which has migrated 120 m at an exponentially decreasing rate over the last 7 years since diversion. The study demonstrates that channel reconfiguration can be effective in mitigating fine sediment flux in upland streams but the full value of this may take many years to achieve whilst the fluvial system, slowly readjusts.

  4. Late Pleistocene and Holocene-Age Columbia River Sediments and Bedforms: Hanford Reach Area, Washington - Part 2

    Energy Technology Data Exchange (ETDEWEB)

    K.R. Fecht, T.E. Marceau

    2006-03-28

    This report presents the results of a geologic study conducted on the lower slopes of the Columbia River Valley in south-central Washington. The study was designed to investigate glaciofluvial and fluvial sediments and bedforms that are present in the river valley and formed subsequent to Pleistocene large-scale cataclysmic flooding of the region.

  5. Dating recent floodplain sediments in the Hawkesbury-Nepean River system, eastern Australia using single-grain quartz OSL

    DEFF Research Database (Denmark)

    Sim, Anna K.; Thomsen, Kristina Jørkov; Murray, K.J.

    2014-01-01

    Two fluvial sediment cores taken from a floodplain of the Hawkesbury-Nepean River system in the Sydney region, eastern Australia are dated using Optically Stimulated Luminescence (OSL) to provide a reliable chronology essential for the management and planning of water resources. Nine charcoal 14C...

  6. Nutrient enrichment coupled with sedimentation favors sea anemones over corals.

    Science.gov (United States)

    Liu, Pi-Jen; Hsin, Min-Chieh; Huang, Yen-Hsun; Fan, Tung-Yung; Meng, Pei-Jie; Lu, Chung-Cheng; Lin, Hsing-Juh

    2015-01-01

    Fine sediments, which account for the majority of total fluvial sediment flux, have been suggested to degrade coral reefs on a global scale. Furthermore, sediment impacts can be exacerbated by extreme rainfall events associated with global climate change and anthropogenic nutrient enrichment. We report the findings from a series of mesocosm experiments exploring the effects of short-term sedimentation and nutrient enrichment on the interactions between the hard coral Acropora muricata, the sea anemone Mesactinia ganesis, and the green macroalga Codium edule. Mesocosms were manipulated to simulate either unimpacted reefs or reefs exposed to elevated levels of fine sediments for 10 or 14 days to simulate the effects of heavy rainfall. The first and second experiments were aimed to examine the effects of inorganic and organic sediments, respectively. The third experiment was designed to examine the interactive effects of nutrient enrichment and elevated sediment loads. Neither inorganic nor organic sediment loadings significantly affected the physiological performance of the coral, but, importantly, did reduce its ability to compete with other organisms. Photosynthetic efficiencies of both the green macroalga and the sea anemone increased in response to both sediment loadings when they were simultaneously exposed to nutrient enrichment. While organic sediment loading increased the nitrogen content of the green macroalga in the first experiment, inorganic sediment loading increased its phosphorus content in the second experiment. The coral mortality due to sea anemones attack was significantly greater upon exposure to enriched levels of organic sediments and nutrients. Our findings suggest that the combined effects of short-term sedimentation and nutrient enrichment could cause replacement of corals by sea anemones on certain coral reefs.

  7. Nutrient enrichment coupled with sedimentation favors sea anemones over corals.

    Directory of Open Access Journals (Sweden)

    Pi-Jen Liu

    Full Text Available Fine sediments, which account for the majority of total fluvial sediment flux, have been suggested to degrade coral reefs on a global scale. Furthermore, sediment impacts can be exacerbated by extreme rainfall events associated with global climate change and anthropogenic nutrient enrichment. We report the findings from a series of mesocosm experiments exploring the effects of short-term sedimentation and nutrient enrichment on the interactions between the hard coral Acropora muricata, the sea anemone Mesactinia ganesis, and the green macroalga Codium edule. Mesocosms were manipulated to simulate either unimpacted reefs or reefs exposed to elevated levels of fine sediments for 10 or 14 days to simulate the effects of heavy rainfall. The first and second experiments were aimed to examine the effects of inorganic and organic sediments, respectively. The third experiment was designed to examine the interactive effects of nutrient enrichment and elevated sediment loads. Neither inorganic nor organic sediment loadings significantly affected the physiological performance of the coral, but, importantly, did reduce its ability to compete with other organisms. Photosynthetic efficiencies of both the green macroalga and the sea anemone increased in response to both sediment loadings when they were simultaneously exposed to nutrient enrichment. While organic sediment loading increased the nitrogen content of the green macroalga in the first experiment, inorganic sediment loading increased its phosphorus content in the second experiment. The coral mortality due to sea anemones attack was significantly greater upon exposure to enriched levels of organic sediments and nutrients. Our findings suggest that the combined effects of short-term sedimentation and nutrient enrichment could cause replacement of corals by sea anemones on certain coral reefs.

  8. The late-glacial fluvial terrace t7 at Raunheim (lower River Main), Germany. Constraining the chronological placement by optical stimulated luminescence dating.

    Science.gov (United States)

    Thiemeyer, Heinrich; Kadereit, Annette; Zipf, Lars; Flettner, Stephan

    2017-04-01

    The lower River Main valley exhibits up to seven fluvial terrace levels (t1 - t7, according to the stratigraphy of Semmel 1969). The lowermost terrace (t7) represents the most recently formed level which due to stratigraphical considerations is assumed to be of Late Pleistocene age (Semmel 1969). However, the chronological placement of the terrace has not been determined by numerical dating so far. The area was apparently roamed by Late Palaeolithic people as evidenced by artefacts which were discovered on a former sandy river bank between 87 m and 91 m above sea level on top of the t7 east of the town of Raunheim. We took this opportunity to open four trenches in order to localize additional in situ Palaeolithic artefacts and to investigate the stratigraphy of the sediments and soils and, for the first time, to provide numerical ages in order to narrow down the period of the t7 activity. Eight samples from three profiles in three of the trenches were collected for optical stimulated (OSL) dating. OSL dating occurred applying a blue light stimulated luminescence (BLSL) single aliquot regeneration (SAR) protocol (Murray & Wintle 2000) to small aliquots (few 102 grains) of quartz coarse grain separates (125 - 212 µm). The trenches showed that the t7 sediments consist of fluvial sand over gravel. They are overlain by calcareous loamy and sandy overbank deposits. At the investigated site the Holocene Cambisol at the surface passes into a Gleysol that has developed in a palaeochannel which is incised into the t7. The trenches revealed further that only parts of the Late Palaeolithic site are in situ and therefore contemporaneous with the fluvial sediments beneath the Cambisol. The upper part of the sections consists of colluvial deposits lying on truncated Cambisols. The OSL dating places the section into the period spanning the last glacial maximum (LGM) / late glacial to the late Holocene. The oldest investigated fluvial t7 sediments date around 24.7 ka. Slightly

  9. The Effects of Vegetation Succession and Landscape on the Evolution of Soil Properties: A Chronosequence Study Along the Proglacial Area of Skaftafellsjökull Glacier, SE Iceland

    Science.gov (United States)

    Vilmundardóttir, O. K.; Gísladóttir, G.; Lal, R.

    2014-12-01

    On young soils developing along the recessional path left by the Skaftafellsjökull glacier, SE-Iceland, we investigated the soil development, vegetation succession and landscape representing an age chronosequence of 120 years. In total, 54 sampling sites were distributed along three moraines representing surfaces exposed for 8, 65 and 120 years. For comparison, soil samples were collected from nearby birch woodlands, representing soils in a mature ecosystem likely to establish on the moraines in the future. The youngest moraines were sparsely vegetated with only 10% cover of mosses and grasses. The plant cover increased to 67% after 120 years, and was characterized by mosses (38%), dwarf shrubs (20%) and low growing birch (3.5%). Consequently, the soil formed over 120 years contained 1.1 kg C m-2 in the surface layer (0-10 cm), or about one third of the 3.2 kg C m-2 in soil under the woodlands. The N stock was estimated at 0.06 kg N m-2after 120 yrs, almost one fourth of that under the woodlands. The data suggest that landscape affects vegetation establishment and in turn, both landscape and vegetation affect soil development. Thus, concentrations of soil organic carbon (SOC), N and noncrystalline oxalate extractable Al and Fe were higher within depressions than on ridges and slopes. The comparison of SOC stock in the moraine-derived soils with that under the birch woodlands showed that the young proglacial soils still have a large potential to accrete SOC within the developing pedosphere. With the observed accrual rate of 9.1 g C m-2 yr-1in the top 10 cm, it may take the moraine soils an additional 220 yrs to accrue SOC stocks comparable with those under the birch forest. Given the fact that all Icelandic glaciers are receding, assessing SOC sequestration in new soil formation may be important to off-setting some of anthropogenic emissions. The research is funded by the University of Iceland Doctoral Fund, the University of Iceland Trust Fund, the Landsvirkjun

  10. Fluvial facies reservoir productivity prediction method based on principal component analysis and artificial neural network

    Directory of Open Access Journals (Sweden)

    Pengyu Gao

    2016-03-01

    Full Text Available It is difficult to forecast the well productivity because of the complexity of vertical and horizontal developments in fluvial facies reservoir. This paper proposes a method based on Principal Component Analysis and Artificial Neural Network to predict well productivity of fluvial facies reservoir. The method summarizes the statistical reservoir factors and engineering factors that affect the well productivity, extracts information by applying the principal component analysis method and approximates arbitrary functions of the neural network to realize an accurate and efficient prediction on the fluvial facies reservoir well productivity. This method provides an effective way for forecasting the productivity of fluvial facies reservoir which is affected by multi-factors and complex mechanism. The study result shows that this method is a practical, effective, accurate and indirect productivity forecast method and is suitable for field application.

  11. Salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  12. Fluvial processes and vegetation - Glimpses of the past, the present, and perhaps the future.

    Science.gov (United States)

    Hupp, Cliff R.; Osterkamp, Waite R.

    2010-01-01

    "Most research before 1960 into interactions among fluvial processes, resulting landforms, and vegetation was descriptive. Since then, however, research has become more detailed and quantitative permitting numerical modeling and applications including agricultural-erosion abatement and rehabilitation of altered

  13. On extracting sediment transport information from measurements of luminescence in river sediment

    Science.gov (United States)

    Gray, Harrison J.; Tucker, Gregory E.; Mahan, Shannon; McGuire, Chris; Rhodes, Edward J.

    2017-01-01

    Accurately quantifying sediment transport rates in rivers remains an important goal for geomorphologists, hydraulic engineers, and environmental scientists. However, current techniques for measuring long-time scale (102–106 years) transport rates are laborious, and formulae to predict transport are notoriously inaccurate. Here we attempt to estimate sediment transport rates by using luminescence, a property of common sedimentary minerals that is used by the geoscience community for geochronology. This method is advantageous because of the ease of measurement on ubiquitous quartz and feldspar sand. We develop a model from first principles by using conservation of energy and sediment mass to explain the downstream pattern of luminescence in river channel sediment. We show that the model can accurately reproduce the luminescence observed in previously published field measurements from two rivers with very different sediment transport styles. The model demonstrates that the downstream pattern of river sand luminescence should show exponential-like decay in the headwaters which asymptotes to a constant value with further downstream distance. The parameters from the model can then be used to estimate the time-averaged virtual velocity, characteristic transport lengthscale, storage time scale, and floodplain exchange rate of fine sand-sized sediment in a fluvial system. The sediment transport values predicted from the luminescence method show a broader range than those reported in the literature, but the results are nonetheless encouraging and suggest that luminescence demonstrates potential as a sediment transport indicator. However, caution is warranted when applying the model as the complex nature of sediment transport can sometimes invalidate underlying simplifications.

  14. On extracting sediment transport information from measurements of luminescence in river sediment

    Science.gov (United States)

    Gray, Harrison J.; Tucker, Gregory E.; Mahan, Shannon A.; McGuire, Chris; Rhodes, Edward J.

    2017-03-01

    Accurately quantifying sediment transport rates in rivers remains an important goal for geomorphologists, hydraulic engineers, and environmental scientists. However, current techniques for measuring long-time scale (102-106 years) transport rates are laborious, and formulae to predict transport are notoriously inaccurate. Here we attempt to estimate sediment transport rates by using luminescence, a property of common sedimentary minerals that is used by the geoscience community for geochronology. This method is advantageous because of the ease of measurement on ubiquitous quartz and feldspar sand. We develop a model from first principles by using conservation of energy and sediment mass to explain the downstream pattern of luminescence in river channel sediment. We show that the model can accurately reproduce the luminescence observed in previously published field measurements from two rivers with very different sediment transport styles. The model demonstrates that the downstream pattern of river sand luminescence should show exponential-like decay in the headwaters which asymptotes to a constant value with further downstream distance. The parameters from the model can then be used to estimate the time-averaged virtual velocity, characteristic transport lengthscale, storage time scale, and floodplain exchange rate of fine sand-sized sediment in a fluvial system. The sediment transport values predicted from the luminescence method show a broader range than those reported in the literature, but the results are nonetheless encouraging and suggest that luminescence demonstrates potential as a sediment transport indicator. However, caution is warranted when applying the model as the complex nature of sediment transport can sometimes invalidate underlying simplifications.

  15. Compounding effects of sea level rise and fluvial flooding.

    Science.gov (United States)

    Moftakhari, Hamed R; Salvadori, Gianfausto; AghaKouchak, Amir; Sanders, Brett F; Matthew, Richard A

    2017-09-12

    Sea level rise (SLR), a well-documented and urgent aspect of anthropogenic global warming, threatens population and assets located in low-lying coastal regions all around the world. Common flood hazard assessment practices typically account for one driver at a time (e.g., either fluvial flooding only or ocean flooding only), whereas coastal cities vulnerable to SLR are at risk for flooding from multiple drivers (e.g., extreme coastal high tide, storm surge, and river flow). Here, we propose a bivariate flood hazard assessment approach that accounts for compound flooding from river flow and coastal water level, and we show that a univariate approach may not appropriately characterize the flood hazard if there are compounding effects. Using copulas and bivariate dependence analysis, we also quantify the increases in failure probabilities for 2030 and 2050 caused by SLR under representative concentration pathways 4.5 and 8.5. Additionally, the increase in failure probability is shown to be strongly affected by compounding effects. The proposed failure probability method offers an innovative tool for assessing compounding flood hazards in a warming climate.

  16. Biophysical interactions in fluvial ecosystems: effects of submerged aquatic macrophytes on hydro-morphological processes and ecosystem functioning

    Science.gov (United States)

    Cornacchia, Loreta; Davies, Grieg; Grabowski, Robert; van der Wal, Daphne; van de Koppel, Johan; Wharton, Geraldene; Bouma, Tjeerd

    2016-04-01

    Strong mutual interactions occur at the interface between biota and physical processes in biogeomorphic ecosystems, possibly resulting in self-organized spatial patterns. While these interactions and feedbacks have been increasingly studied in a wide range of landscapes previously, they are still poorly understood in lower energy fluvial systems. Consequently, their impact on the functioning of aquatic ecosystems is largely unknown. In this study we investigate the role of aquatic macrophytes as biological engineers of flow and sediment in lowland streams dominated by water crowfoot (Ranunculus spp.). Using field measurements from two annual growth cycles, we demonstrate that seasonally-changing macrophyte cover maintains relative constant flow rates, both within and between vegetation, despite temporal changes in channel flow discharge. By means of a mathematical model representing the interaction between hydrodynamics and vegetation dynamics, we reveal that scale-dependent feedbacks between plant growth and flow redistribution explain the influence of macrophytes on stabilizing flow rates. Our analysis reveals important implications for ecosystem functions. The creation of fast-flowing channels allows an adequate conveyance of water throughout the annual cycle; yet, patches also have a significant influence on sediment dynamics leading to heterogeneous habitats, thereby facilitating other species. As a last step we investigate the consequences on stream ecosystem functioning, by exploring the relationship between changes in macrophyte cover and the provision of different ecosystem functions (e.g. water conveyance, sediment trapping). Our results highlight that self-organization promotes the combination of multiple ecosystem functions through its effects on hydrological and morphological processes within biogeomorphic ecosystems.

  17. Is similar the distribution of Chironomidae (Diptera and Oligochaeta (Annelida, Clitellata in a river and a lateral fluvial area?

    Directory of Open Access Journals (Sweden)

    Daniela Aparecida Silveira Cesar

    2017-05-01

    Full Text Available Abstract Numerous factors may affect the pattern of distribution of benthic fauna in a river mouth region and, among the macroinvertebrates, Chironomidae and Oligochaeta are the most abundant groups and most tolerant to environmental changes. Aim The aim of this study was to evaluate the controlling factors of and a possible similarity between Chironomidae and Oligochaeta assemblies at two close sites, the mouth of the Guareí River into the Paranapanema River (São Paulo, Brazil and its lateral fluvial area. Methods Fauna samples were collected every three months during one year. Water physical and chemical variables and sediment variables were also determined in the same period. Results Both assemblies presented low density variability over time in the lateral area due to sediment characteristics and environmental factors. Taxa Caladomyia, Parachironomus, Pristina sp., Pristina osborni, Bothrioneurum and Opistocysta funiculus were recorded at this site. The Guareí River presented both greater temporal and spatial variations, attributed mainly to a reduction in the water level. Greater organism abundance, especially of Chironomus and Tubificinae, was observed in the river. Conclusions Dissimilarity in temporal and spatial distributions of Chironomidae and Oligochaeta was attributed to peculiar characteristics of the two study sites, a river channel and a lateral area. Reduction in the water level over the year was the main controlling factor of Chironomidae and Oligochaeta richness and density in the river. In the lateral area, the presence and abundance of certain taxa were determined by the nature of the sediment and water physical and chemical variables.

  18. Passive acoustic monitoring of bed load for fluvial applications

    Science.gov (United States)

    The sediment transported as bed load in streams and rivers is notoriously difficult to monitor cheaply and accurately. Passive acoustic methods are relatively simple, inexpensive, and provide spatial integration along with high temporal resolution. In 1963 work began on monitoring emissions from par...

  19. Overview of selected surrogate technologies for high-temporal resolution suspended-sediment monitoring

    Science.gov (United States)

    Gray, John R.; Gartner, Jeffrey W.

    2010-01-01

    Traditional methods for characterizing selected properties of suspended sediments in rivers are being augmented and in some cases replaced by cost-effective surrogate instruments and methods that produce a temporally dense time series of quantifiably accurate data for use primarily in sediment-flux computations. Turbidity is the most common such surrogate technology, and the first to be sanctioned by the U.S. Geological Survey for use in producing data used in concert with water-discharge data to compute sediment concentrations and fluxes for storage in the National Water Information System. Other technologies, including laser-diffraction, digital photo-optic, acoustic-attenuation and backscatter, and pressure-difference techniques are being evaluated for producing reliable sediment concentration and, in some cases, particle-size distribution data. Each technology addresses a niche for sediment monitoring. Their performances range from compelling to disappointing. Some of these technologies have the potential to revolutionize fluvial-sediment data collection, analysis, and availability.

  20. The exceptional sediment load of fine-grained dispersal systems: Example of the Yellow River, China.

    Science.gov (United States)

    Ma, Hongbo; Nittrouer, Jeffrey A; Naito, Kensuke; Fu, Xudong; Zhang, Yuanfeng; Moodie, Andrew J; Wang, Yuanjian; Wu, Baosheng; Parker, Gary

    2017-05-01

    Sedimentary dispersal systems with fine-grained beds are common, yet the physics of sediment movement within them remains poorly constrained. We analyze sediment transport data for the best-documented, fine-grained river worldwide, the Huanghe (Yellow River) of China, where sediment flux is underpredicted by an order of magnitude according to well-accepted sediment transport relations. Our theoretical framework, bolstered by field observations, demonstrates that the Huanghe tends toward upper-stage plane bed, yielding minimal form drag, thus markedly enhancing sediment transport efficiency. We present a sediment transport formulation applicable to all river systems with silt to coarse-sand beds. This formulation demonstrates a remarkably sensitive dependence on grain size within a certain narrow range and therefore has special relevance to silt-sand fluvial systems, particularly those affected by dams.

  1. The fate of carbon in floodplain sediments: A biogeochemical approach

    Science.gov (United States)

    Alderson, Danielle; Evans, Martin; Rothwell, James; Boult, Stephen; Rhodes, Edward

    2015-04-01

    Inland waters including fluvial systems and their associated sediments have been predominantly overlooked as part of global carbon budgets until recently. In the UK, peatlands are dynamically eroding, with the eventual result being 'off-site' greenhouse gas emissions, which must be incorporated into carbon budgets for management strategies. Evans et al. (2013) concluded fluvial systems are active cyclers of carbon, with 50-90% of particulate organic carbon (POC) exported from peatlands eventually emitted as CO2. Floodplains, although commonly regarded as zones of carbon storage, have been identified as potential hotspots of carbon cycling in the fluvial system with a key process being decomposition of POC. Decomposition is known to involve mass loss with selective transformation of labile compounds such as polysaccharides, and preferential preservation of more resistant compounds (refractory aromatics or aliphatics). Several decomposition proxies including FTIR band intensities, hydrogen indices and C/N ratios, correlated with molecular structure determinations using pyrolysis GC-MS, have been used successfully in peat cores (Biester et al., 2013), to disentangle changes due to decomposition and those that are related to vegetation variation. The aim of this research is to determine whether similar techniques can be applied to arguably more complex systems such as floodplains, to examine stratigraphic records of carbon cycling. Initial results from sediment cores taken within a floodplain environment downstream of the Bleaklow Plateau in the Peak District, UK will be presented. An initial OSL date of 640±90 years BP together with assessment of the valley morphology using high resolution LiDAR DEM's indicate potential interaction of post glacial landslide features with the onset of substantial peat erosion, conditioning the landscape to interrupt the transport of carbon down the fluvial network. The floodplain under investigation is a potential hotspot for carbon

  2. 100 kyr fluvial cut-and-fill terrace cycles since the Middle Pleistocene in the southern Central Andes, NW Argentina

    Science.gov (United States)

    Tofelde, Stefanie; Schildgen, Taylor F.; Savi, Sara; Pingel, Heiko; Wickert, Andrew D.; Bookhagen, Bodo; Wittmann, Hella; Alonso, Ricardo N.; Cottle, John; Strecker, Manfred R.

    2017-09-01

    Fluvial fill terraces in intermontane basins are valuable geomorphic archives that can record tectonically and/or climatically driven changes of the Earth-surface process system. However, often the preservation of fill terrace sequences is incomplete and/or they may form far away from their source areas, complicating the identification of causal links between forcing mechanisms and landscape response, especially over multi-millennial timescales. The intermontane Toro Basin in the southern Central Andes exhibits at least five generations of fluvial terraces that have been sculpted into several-hundred-meter-thick Quaternary valley-fill conglomerates. New surface-exposure dating using nine cosmogenic 10Be depth profiles reveals the successive abandonment of these terraces with a 100 kyr cyclicity between 75 ± 7 and 487 ± 34 ka. Depositional ages of the conglomerates, determined by four 26Al/10Be burial samples and U-Pb zircon ages of three intercalated volcanic ash beds, range from 18 ± 141 to 936 ± 170 ka, indicating that there were multiple cut-and-fill episodes. Although the initial onset of aggradation at ∼1 Ma and the overall net incision since ca. 500 ka can be linked to tectonic processes at the narrow basin outlet, the superimposed 100 kyr cycles of aggradation and incision are best explained by eccentricity-driven climate change. Within these cycles, the onset of river incision can be correlated with global cold periods and enhanced humid phases recorded in paleoclimate archives on the adjacent Bolivian Altiplano, whereas deposition occurred mainly during more arid phases on the Altiplano and global interglacial periods. We suggest that enhanced runoff during global cold phases - due to increased regional precipitation rates, reduced evapotranspiration, or both - resulted in an increased sediment-transport capacity in the Toro Basin, which outweighed any possible increases in upstream sediment supply and thus triggered incision. Compared with two

  3. Rangeland management and fluvial geomorphology in northern Tanzania.

    Science.gov (United States)

    Miller, Brian W; Doyle, Martin W

    2014-06-01

    Researchers have independently documented the effects of land use on rivers and threats to river management institutions, but the relationship between changes in institutional context and river condition is not well described. This study assesses the connections between resource management institutions, land use, and rivers by integrating social science, geospatial analysis, and geomorphology. In particular, we measured hydraulic geometry, sediment size distributions, and estimated sediment yield for four rivers in northern Tanzania and conducted semistructured interviews that assessed corresponding resource management institutions. Communities managed rivers through both customary (traditional, nonstate) and government institutions, but the differences in the resource management policies and practices of the study rivers themselves were fairly subtle. Clearer differences were found at broader scales; the four watersheds exhibited substantial differences in land cover change and sediment yield associated with the location of settlements, roadways, and cultivation. Unexpectedly, these recent land use changes did not initiate a geomorphic response in rivers. The long history of grazing by domestic and wild ungulates may have influenced water and sediment supplies such that river channel dimensions are more resistant to changes in land use than other systems or have already adjusted to predominant changes in boundary conditions. This would suggest that not all rivers will have the anticipated responses to contemporary land use changes because of antecedent land use patterns; over long time scales (centuries to millennia), the presence of grazers may actually increase the ability of rivers to withstand changes in land use. Our findings point to a need for further interdisciplinary study of dryland rivers and their shifts between system states, especially in areas with a long history of grazing, relatively recent changes in land use, and a dynamic social and

  4. Rangeland management and fluvial geomorphology in northern Tanzania

    Science.gov (United States)

    Miller, Brian W.; Doyle, Martin W.

    2014-06-01

    Researchers have independently documented the effects of land use on rivers and threats to river management institutions, but the relationship between changes in institutional context and river condition is not well described. This study assesses the connections between resource management institutions, land use, and rivers by integrating social science, geospatial analysis, and geomorphology. In particular, we measured hydraulic geometry, sediment size distributions, and estimated sediment yield for four rivers in northern Tanzania and conducted semistructured interviews that assessed corresponding resource management institutions. Communities managed rivers through both customary (traditional, nonstate) and government institutions, but the differences in the resource management policies and practices of the study rivers themselves were fairly subtle. Clearer differences were found at broader scales; the four watersheds exhibited substantial differences in land-cover change and sediment yield associated with the location of settlements, roadways, and cultivation. Unexpectedly, these recent land-use changes did not initiate a geomorphic response in rivers. The long history of grazing by domestic and wild ungulates may have influenced water and sediment supplies such that river channel dimensions are more resistant to changes in land use than other systems or have already adjusted to predominant changes in boundary conditions. This would suggest that not all rivers will have the anticipated responses to contemporary land-use changes because of antecedent land-use patterns; over long time scales (centuries to millennia), the presence of grazers may actually increase the ability of rivers to withstand changes in land use. Our findings point to a need for further interdisciplinary study of dryland rivers and their shifts between system states, especially in areas with a long history of grazing, relatively recent changes in land use, and a dynamic social and

  5. The Ba/Ca record of corals from the Southern Gulf of Mexico: contributions from land-use changes, fluvial discharge and oil-drilling muds.

    Science.gov (United States)

    Carriquiry, José D; Horta-Puga, Guillermo

    2010-09-01

    The Ba/Ca in the growth bands of Montastraea faveolata from the Veracruz Reef System was used to reconstruct the long-term environmental change associated to anthropogenic activity in the Southern Gulf of Mexico (SGM). The 168-yr coral record shows two periods of distinct Ba concentrations: a pre-industrial period (1835-1965: 7.54 micromol/mol) followed by an industrial one (1966-2000: 8.57 micromol/mol). As human population quadrupoled during the latter, sediment load in the fluvial discharge also increased due to changes in land-use, yielding a 14% increase in the Ba-levels. A remarkable finding is that the periods at which the coral Ba/Ca ratio losses its correlation with fluvial discharge coincide exactly with peak periods of high barite consumption (used for oil drilling) in the Northern Gulf of Mexico, and the onset of oil drilling in the SGM. This finding suggests that barite may be one of the dominant sources for dissolved-Ba in the SGM. Copyright 2010 Elsevier Ltd. All rights reserved.

  6. Sedimentation processes in a coral reef embayment: Hanalei Bay, Kauai

    Science.gov (United States)

    Storlazzi, C.D.; Field, M.E.; Bothner, Michael H.; Presto, M.K.; Draut, A.E.

    2009-01-01

    Oceanographic measurements and sediment samples were collected during the summer of 2006 as part of a multi-year study of coastal circulation and the fate of terrigenous sediment on coral reefs in Hanalei Bay, Kauai. The goal of this study was to better understand sediment dynamics in a coral reef-lined embayment where winds, ocean surface waves, and river floods are important processes. During a summer period that was marked by two wave events and one river flood, we documented significant differences in sediment trap collection rates and the composition, grain size, and magnitude of sediment transported in the bay. Sediment trap collection rates were well correlated with combined wave-current near-bed shear stresses during the non-flood periods but were not correlated during the flood. The flood's delivery of fine-grained sediment to the bay initially caused high turbidity and sediment collection rates off the river mouth but the plume dispersed relatively quickly. Over the next month, the flood deposit was reworked by mild waves and currents and the fine-grained terrestrial sediment was advected around the bay and collected in sediment traps away from the river mouth, long after the turbid surface plume was gone. The reworked flood deposits, due to their longer duration of influence and proximity to the seabed, appear to pose a greater long-term impact to benthic coral reef communities than the flood plumes themselves. The results presented here display how spatial and temporal differences in hydrodynamic processes, which result from variations in reef morphology and orientation, cause substantial variations in the deposition, residence time, resuspension, and advection of both reef-derived and fluvial sediment over relatively short spatial scales in a coral reef embayment.

  7. Assessing Potential Algal Blooms in a Shallow Fluvial Lake by Combining Hydrodynamic Modelling and Remote-Sensed Images

    National Research Council Canada - National Science Library

    Monica Pinardi; Andrea Fenocchi; Claudia Giardino; Stefano Sibilla; Marco Bartoli; Mariano Bresciani

    2015-01-01

    .... Due to multiple interplaying factors, understanding the distribution of phytoplankton in fluvial lakes is a complex but fundamental issue, in the context of increasing eutrophication, climate change...

  8. Cauvery River: Late Quaternary Fluvial Process and landforms

    Science.gov (United States)

    Stalin, Manjula; Achyuthan, Hema

    2014-05-01

    tectonics, and fluvial records. The occurrence of low channel gradients, prominent hanging valleys, narrow bedrock and rapid erosion in middle portion of the Cauvery river indicate strong bedrock channel erosion. Drainage density and length of overland flow positively correlated with each other and the relationships are significant at 85% level. In this presentation detailed morphometric analysis supported by field date are presented.

  9. Investigating the use of the dual-polarized and large incident angle of SAR data for mapping the fluvial and aeolian deposits

    Directory of Open Access Journals (Sweden)

    Ahmed Gaber

    2017-12-01

    Full Text Available Mapping the spatial distributions of the fluvial deposits in terms of particles size as well as imaging the near-surface features along the non-vegetated aeolian sand-sheets, provides valuable geological information. Thus this work aims at investigating the contribution of the dual-polarization SAR data in classifying and mapping the surface sediments as well as investigating the effect of the radar incident-angle on improving the images of the hidden features under the desert sand cover. For mapping the fluvial deposits, the covariance matrix ([C2] using four dual-polarized ALOS/PALSAR-1 scenes cover the Wadi El Matulla, East Qena, Egypt were generated. This [C2] matrix was used to generate a supervised classification map with three main classes (gravel, gravel/sand and sand. The polarimetric scattering response, spectral reflectance and temperatures brightness of these 3 classes were extracted. However for the aeolian deposits investigation, two Radarsat-1 and three full-polarimetric ALOS/PALSAR-1 images, which cover the northwestern sandy part of Sinai, Egypt were calibrated, filtered, geocoded and ingested in a GIS database to image the near-surface features. The fluvial mapping results show that the values of the radar backscattered coefficient (σ° and the degree of randomness of the obtained three classes are increasing respectively by increasing their grain size. Moreover, the large incident angle (θi = 39.7 of the Radarsat-1 image has revealed a meandering buried stream under the sand sheet of the northwestern part of Sinai. Such buried stream does not appear in the other optical, SRTM and SAR dataset. The main reason is the enhanced contrast between the low backscattered return from the revealed meandering stream and the surroundings as a result of the increased backscattering intensity, which is related to the relatively large incident angle along the undulated surface of the study area. All archaeological

  10. Sediment Acoustics.

    Science.gov (United States)

    1980-04-02

    approximately one grain size (0.35 mm) out of 600 grain size total. The experiment was repeated with a 2.54 cm thick layer of water filled polyurethane foam ...Kaolinite Clay for Shear Waves 70 it vi .- m -77- I. INTRODUCTION A determination of the viscoelastic properties of ocean sediments can be made by...temperature of these additional viscoelastic properties have not been studied in detail. This section contains shear wave and compressional wave data

  11. Hydraulic Geometry, GIS and Remote Sensing, Techniques against Rainfall-Runoff Models for Estimating Flood Magnitude in Ephemeral Fluvial Systems

    Directory of Open Access Journals (Sweden)

    Rafael Garcia-Lorenzo

    2010-11-01

    Full Text Available This paper shows the combined use of remotely sensed data and hydraulic geometry methods as an alternative to rainfall-runoff models. Hydraulic geometric data and boolean images of water sheets obtained from satellite images after storm events were integrated in a Geographical Information System. Channel cross-sections were extracted from a high resolution Digital Terrain Model (DTM and superimposed on the image cover to estimate the peak flow using HEC-RAS. The proposed methodology has been tested in ephemeral channels (ramblas on the coastal zone in south-eastern Spain. These fluvial systems constitute an important natural hazard due to their high discharges and sediment loads. In particular, different areas affected by floods during the period 1997 to 2009 were delimited through HEC-GeoRAs from hydraulic geometry data and Landsat images of these floods (Landsat‑TM5 and Landsat-ETM+7. Such an approach has been validated against rainfall-surface runoff models (SCS Dimensionless Unit Hydrograph, SCSD, Témez gamma HU Tγ and the Modified Rational method, MRM comparing their results with flood hydrographs of the Automatic Hydrologic Information System (AHIS in several ephemeral channels in the Murcia Region. The results obtained from the method providing a better fit were used to calculate different hydraulic geometry parameters, especially in residual flood areas.

  12. Miocene fluvial systems and palynofloras at the southwestern tip of Africa: Implications for regional and global fluctuations in climate and ecosystems

    Science.gov (United States)

    Roberts, David L.; Sciscio, Lara; Herries, Andy I. R.; Scott, Louis; Bamford, Marion K.; Musekiwa, Chiedza; Tsikos, Harilaos

    2013-09-01

    High amplitude climate fluctuations have been inferred from marine isotope data in the early Neogene, but few well documented terrestrial records exist from this era to gauge the effects of these high latitude events on continental climates and ecosystems. The extensive, three-dimensional exposures of Miocene fluvial and fluvio-lacustrine sediments in the Rondeberg clay pit near Cape Town provide a unique window on this era. Palaeomagnetic data suggests that the deposits accumulated over a period of west coast, the Arrisdrift vertebrate fossil assemblage in Early-Middle Miocene terrace deposits of the Orange River indicate a tropical climate but possibly less humid than in the south, with more open vegetation patterns. The presence of pedogenic calcretes and gypcretes in the deposits suggests periodic extremes of aridity not seen in south; the current pronounced north-aridity gradient from humid temperate to hyper-arid may have had its inception in the earlier Miocene.

  13. Discussion of "Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California" (Schumann et al., 2016. Geomorphology, 268: 322-340)

    Science.gov (United States)

    Pinter, Nicholas; Hardiman, Mark; Scott, Andrew C.; Anderson, R. Scott

    2018-01-01

    Schumann et al. (2016) presented a field assessment of late Pleistocene to Holocene fluvial sediments preserved in the valleys of Santa Rosa Island, California. This is a rigorous study, based on stratigraphic descriptions of 54 sections and numerous radiocarbon ages. The paper makes important contributions that we would like to highlight, but other parts of the paper rely upon overly simplistic interpretations that lead to misleading conclusions. In one case, a conclusion of the Schumann et al. paper has important management implications for Santa Rosa Island and similar locations, compelling us to discuss and qualify this conclusion.

  14. Chronology and evolution of a fluvial/canyon connection around the Last Glacial Maximum: The Bourcart canyon head (western Mediterranean)

    Science.gov (United States)

    Mauffrey, Marie-Aline; Berné, Serge; Gaudin, Matthieu; Jouet, Gwenael

    2013-04-01

    Deeply incised canyons have been described in the Gulf of Lions since the end of the 19th century. Recently, the role of axial incision, as a pathway of high-density flows initiated within streams and cutting across the main thalweg of canyons, has been proposed as a mechanism for canyon evolution, in this area and elsewhere (Baztan et al., 2005). In this study, we used a large data base of very-high resolution seismic profiles in order to determine the precise architecture of the Bourcart (Aude) canyon head. The accurate 3D geometry of the buried and recent incisions through the Bourcart canyon head allows us to draw the pattern of canyon connections with shelf incised valleys. Furthermore, time constraints (and relation with sea-level changes) were obtained through the correlation with the Promess 1 drill site situated in the vicinity of the Bourcart canyon, and with long piston cores retrieved on the continental shelf in the same area. Our results demonstrate the direct connection of fluvial system(s) to present (and buried) axial incisions, and show the progressive evolution of seismic facies from typical "valley-fill" to typical "confined channel-levee" systems. Streams from the East (possibly the Rhone), then from the West (possibly the Agly) of the Gulf of Lions successively fed the canyon head. An important phase of deposition occurred within the canyon head at the onset of sea-level rise, probably in relation with increased water and sediment flux from the Pyrenees during the early Deglacial period. We hypothesize that, during this period, Pyrenean streams seasonally experienced very high-concentration sediment loads, capable of generating high density (probably hyperpycnal) flows in the canyon head. Only such high-concentration flows may explain the meandering pattern of axial incisions observed at very shallow depths, within the canyon head. Reference: Baztan, J. et al., 2005, Marine and Petroleum Geology, 22, 805-826

  15. Near-bed turbulence and sediment flux measurements in tidal channels

    Science.gov (United States)

    Wright, S.A.; Whealdon-Haught, D.R.

    2012-01-01

    Understanding the hydrodynamics and sediment transport dynamics in tidal channels is important for studies of estuary geomorphology, sediment supply to tidal wetlands, aquatic ecology and fish habitat, and dredging and navigation. Hydrodynamic and sediment transport data are essential for calibration and testing of numerical models that may be used to address management questions related to these topics. Herein we report preliminary analyses of near-bed turbulence and sediment flux measurements in the Sacramento-San Joaquin Delta, a large network of tidal channels and wetlands located at the confluence of the Sacramento and San Joaquin Rivers, California, USA (Figure 1). Measurements were made in 6 channels spanning a wide range of size and tidal conditions, from small channels that are primarily fluvial to large channels that are tidally dominated. The results of these measurements are summarized herein and the hydrodynamic and sediment transport characteristics of the channels are compared across this range of size and conditions.

  16. POM Pulses: Characterizing the Physical and Chemical Properties of Particulate Organic Matter (POM) Mobilized by Large Storm Events and its Influence on Receiving Fluvial Systems

    Science.gov (United States)

    Johnson, E. R.; Rowland, R. D.; Protokowicz, J.; Inamdar, S. P.; Kan, J.; Vargas, R.

    2016-12-01

    Extreme storm events have tremendous erosive energy which is capable of mobilizing vast amounts of material from watershed sources into fluvial systems. This complex mixture of sediment and particulate organic matter (POM) is a nutrient source, and has the potential to impact downstream water quality. The impact of POM on receiving aquatic systems can vary not only by the total amount exported but also by the various sources involved and the particle sizes of POM. This study examines the composition of POM in potential sources and within-event POM by: (1) determining the amount and quality of dissolved organic matter (DOM) that can be leached from coarse, medium and fine particle classes; (2) assessing the C and N content and isotopic character of within-event POM; and (3) coupling physical and chemical properties to evaluate storm event POM influence on stream water. Storm event POM samples and source sediments were collected from a forested headwater catchment (second order stream) in the Piedmont region of Maryland. Samples were sieved into three particle classes - coarse (2mm-1mm), medium (1mm-250µm) and fine (organic matter was analyzed. Carbon (C) and Nitrogen (N) amount, C:N ratio, and isotopic analysis of 13C and 15N were performed on solid state event and source material. Future work will include examination of microbial communities associated with POM particle size classes. Physical size class separation of within-event POM exhibited differences in C:N ratios, δ15N composition, and extracted DOM lability. Smaller size classes exhibited lower C:N ratios, more enriched δ15N and more recalcitrant properties in leached DOM. Source material had varying C:N ratios and contributions to leached DOM. These results indicate that both source and size class strongly influence the POM contribution to fluvial systems during large storm events.

  17. High- and low-latitude forcing of the Nile River regime during the Holocene inferred from laminated sediments of the Nile deep-sea fan

    NARCIS (Netherlands)

    Blanchet, C.; Tjallingii, R.; Frank, M.; Lorenzen, J.; Reitz, A.; Brown, K.; Feseker, T.; Brückmann, W.

    2013-01-01

    Sediments deposited on deep-sea fans are an excellent geological archive to reconstruct past changes in fluvial discharge. Here we present a reconstruction of changes in the regime of the Nile River during the Holocene obtained using bulk elemental composition, grain-size analyses and radiogenic

  18. Comparison of single-grain and small-aliquot OSL dose estimates in < 3000 years old river sediments from South India

    DEFF Research Database (Denmark)

    Thomas, P.J.; Jain, M.; Juyal, N.

    2005-01-01

    We report on OSL dose distributions derived from small-aliquot and single grains of quartz in young fluvial sediments sampled from the Penner River basin, South India. The single-grain dose distributions suggest that 13 out of 19 samples were well bleached. In many well-bleached samples, there wa...

  19. Effects of a small-scale, abandoned gold mine on the geochemistry of fine stream-bed and floodplain sediments in the Horsefly River watershed, British Columbia, Canada

    NARCIS (Netherlands)

    Clark, Deirdre E.; Vogels, Marjolein; van der Perk, Marcel; Owens, Philip N.; Petticrew, Ellen L.

    Mining is known to be a major source of metal contamination for fluvial systems worldwide. Monitoring and understanding the effects on downstream water and sediment quality is essential for its management and to mitigate against detrimental environmental impacts. This study aimed to examine the

  20. Effects of a small-scale, abandoned gold mine on the geochemistry of fine stream-bed and floodplain sediments in the Horsefly River watershed, British Columbia, Canada

    NARCIS (Netherlands)

    Clark, Deirdre E.; Vogels, Marjolein; van der Perk, Marcel; Owens, Philip N.; Petticrew, Ellen L.

    2014-01-01

    Mining is known to be a major source of metal contamination for fluvial systems worldwide. Monitoring and understanding the effects on downstream water and sediment quality is essential for its management and to mitigate against detrimental environmental impacts. This study aimed to examine the

  1. Element geochemical analysis of the contribution of aeolian sand to suspended sediment in desert stream flash floods.

    Science.gov (United States)

    Jia, Xiaopeng; Wang, Haibing

    2014-01-01

    The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream.

  2. Element Geochemical Analysis of the Contribution of Aeolian Sand to Suspended Sediment in Desert Stream Flash Floods

    Directory of Open Access Journals (Sweden)

    Xiaopeng Jia

    2014-01-01

    Full Text Available The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream.

  3. THE ROLE OF THE HYDROLOGICAL FACTOR IN HABITAT DYNAMICS WITHIN THE FLUVIAL CORRIDOR OF DANUBE

    Directory of Open Access Journals (Sweden)

    GH. CLOŢĂ

    2012-03-01

    Full Text Available The role of the hydrological factor in habitat dynamics within the fluvial corridor of Danube. This paper had explored the connections between river hydrology with its changes and habitat dynamics. The fluvial corridor integrates spatially the channel and parts of its floodplain affected by periodical flooding and could be considered as an ecological corridor because of the size of the hydrosystem. The river and its ecosystems depend on geomorphogenetic and biological function and, thus creating a inter-dependence transposed into a concept, namely the fluvial hydrosystem, proposed firstly by Roux 1982, Amoros 1987. The hydrosystem is an ecological complex system constituted of biotopes and specific biocenoses of stream waters, stagnant water bodies, semi-aquatic, terrestrial ecosystems localized in the space of floodplain modeled directly and indirectly by river’s active force.

  4. Last millenium environmental changes in Lake Bertrand sediments, Chilean Patagonia

    Science.gov (United States)

    Sacré, V.; Fagel, N.; Schmidt, S.; Alvarez, D.; Araneda, A.; Urrutia, R.

    2012-04-01

    Our study focuses on a multiproxy analysis of sedimentary records from Lago Bertrand (area 50 km2; 227 masl; 46°55'S 72°50'W). Three cores were retrieved during fieldtrips in 2009 and 2011 with an Uwitec gravity corer. One core was collected in the main lake (LBt09, 102 cm) and two others in a lateral extension (LBb11-A, 162 cm and LBb11-B, 156 cm). Data 210Pb and 137Cs give average sedimentation rates of 2 mm/yr for the upper core section from the main lake, allowing a decennial resolution. Our aim is to document the climatic variability during the last millennium in Northern Patagonia and its impact on the environment. Lago Bertrand is separated from a pro-glacial lake (Lago Plomo) by a morainic barrier. The sediments of this lake are mainly composed of clayed silts and very few sandy silts. In the cores from the Eastern branch of Lago Bertrand, X-ray radiographies and magnetic susceptibility profiles evidence well-defined pluri-millimetric laminations with organic-rich layers, especially in the central core section. In the main lake, X-ray radiographies show diffuse pluri-millimetric laminations while magnetic susceptibility profiles do not confirm it. The sediments of the main lake appear more homogeneous with less organic-rich layers. They are characterized by low C/N ratio (10), supporting an important aquatic productivity; high inorganic content (90-95% of the bulk sediment); two peaks in the biological silica profile; and abundant diatoms (50-100 µm). According to the age model, the changes in aquatic productivity occurred between 1700 and 1850 AD. The cores from the Eastern branch of Lago Bertrand are under investigation to confirm the extension of the sedimentological changes observed in the main lake. The main sedimentological change observed in Lago Bertrand occurs during an interval equivalent to a part of the Little Ice Age. A similar biogenic silica-rich layer was also recorded in another relatively distant lake (Lago Thompson at 45°30'S, 72°47

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

    Science.gov (United States)

    Rech, J. A.; Latorre, C.

    2004-12-01

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

  6. Late Holocene lowland fluvial archives and geoarchaeology: Utrecht's case study of Rhine river abandonment under Roman and Medieval settlement

    Science.gov (United States)

    van Dinter, Marieke; Cohen, Kim M.; Hoek, Wim Z.; Stouthamer, Esther; Jansma, Esther; Middelkoop, Hans

    2017-06-01

    Fluvial lowlands have become attractive human settling areas all around the world over the last few millennia. Because rivers kept changing their course and networks due to avulsion, the sedimentary sequences in these areas are archives of both fluvial geomorphological and archaeological development. We integrated geological and archaeological datasets to demonstrate the concurrence of the gradual abandonment of a major Rhine channel (Utrecht, The Netherlands), the development of human habitation in the area, and the interactions between them. The Utrecht case study highlights the stage-wise abandonment of a natural river channel, due to avulsion, coincident with intensifying human occupation in Roman and Early Medieval times (1st millennium AD). The analyses make maximum use of very rich data sets available for the study area and the tight age control that the geo-archaeological dataset facilitates, offering extra means of time-control to document the pacing of the abandonment process. This allows us to quantify change in river dimensions and meander style and to provide discharge estimates for successive stages of the abandonment phase over a 1000-year period of abandonment succession, from mature river to eventual Late Medieval overbuilt canal when the Rhine branch had lost even more discharge. Continued geomorphic development during this period - which includes the 'Dark Ages' (450-1000 AD) - appears to have been crucial in the development of Utrecht from Roman army fortress to Medieval ecclesial centre. The settlement dynamics in and around the city of Utrecht changed during the various phases of abandonment. In the bifurcating network of river branches forming the Rhine-Meuse delta, the main Rhine branch hosted the Roman limes military border and transport route. The Rhine- Vecht bifurcation at Utrecht provided an excellent location to raise a Roman fort. Continued geomorphic activity during abandonment in Early Medieval times was characterised by enhanced

  7. Selected fluvial monazite deposits in the southeastern United States

    Science.gov (United States)

    Overstreet, William C.; White, A.M.; Theobald, P.K.; Caldwell, D.W.

    1971-01-01

    Farther southwest in Georgia, around Griffin and Zebullon, along streams tributary to the Flint River in the monazite belt the flood plains are generally small and discontinuous, and only about 1 percent of the sediment is gravel. The area between Griffin, Zebullon, and the Flint River is underlain by biotite schist and biotite gneiss into which biotite granite has been intruded. Only along one stream, Flat Creek, which drains monazite-bearing granite near Zetella, Ga., are the tenors in monazite even moderately high, but a combination of thick, clayey overburden and discontinuous flood plains make the stream unsuitable for placer mining. Elsewhere in the Flint River area the heavy-mineral concentrates contain less than 1 percent monazite. The southwesternmost area in which reconnaissance of the monazite belt was conducted includes a groups of southwest-flowing tributaries to the Chattahoochee River north of Pine Mountain and near La Grange, Ga. A combination of three characteristics of the alluvium make the area unfavorable for mining: (1) the upper half of the sedimentary sequence is clay and silt, (2) there is scant gravel, and (3) much of the sand is fine grained. Monazite is associated with the Snelson Granite, schists, and gneisses north of the Towaliga fault, but even in this area the tenor of most riffle sediments is only 0.1 to 0.5 pound of monazite per cubic yard, and the average tenor of the alluvium is about 0.2 pound per cubic Yard. Rocks south of the Towaliga fault contain scant monazite. The monazite-bearing area in the drainage basin of the Chattahoochee River has no monazite placers. Evidence from the areas on the Flint and Chattahoochee Rivers shows that streams in western Georgia are a much poorer source of monazite than streams farther to the northeast in Georgia, South Carolina, and North Carolina. Also, the northeastern part of the belt in the drainage basins of the Yadkin and Dan Rivers is a poorer source for monazite than the area between

  8. A Three-dimensional Two-phase Mixture Model for Sediment Transport

    Science.gov (United States)

    Huang, Hai; Zhong, Deyu; Zhang, Hongwu; Zhang, Yinglong J.; Li, Xiaonan

    2017-04-01

    Suspended load often constitutes a large portion of the total load in a fluvial river. In classical fluvial numeric models, flows carrying suspended sediment are usually modeled by the Reynolds averaged equations directly borrowed from the classical fluid dynamics for single-phase flows with an advection-diffusion equation and single-phase turbulence model is adopted to close the equations. Due to the omission of the effect of the sediment on fluid, results from the classical models can deviate significantly from experimental and field observations. In this paper, we develop a three-dimensional numerical model based on two-phase mixture theory to study the sediment-laden flows. The two-phase mixture equations are closed by a two-phase mixture turbulence model derived from two-fluid turbulence model. The two-phase mixture model therefore inherits the essential capabilities of two-fluid models in considering inter-phase interaction, but without solving the full set of governing equations for the two-fluid models. Two-phase mixture equations have similar form to the governing equations for classical fluvial hydraulics, thus allowing us to embed the two-phase mixture model into SCHISM, a 3D unstructured-grid model for oceans, estuaries and rivers. We verify the new model with a set of experiments , and the results show that the new model is valid for sediment-laden flows covering a wide range of particle diameters and concentrations. We also apply the new model to the study of representative flood events in the Lower Yellow River (LYR), and investigate sediment distributions, velocity profiles, circulation flows in river bends, flood propagation and erosion and deposition patterns. The computed water surface elevation, cross-sectional bathymetry and sediment concentration show good agreement with the measured data.

  9. Fluidized-sediment pipes in Gale crater, Mars, and possible Earth analogs

    Science.gov (United States)

    Rubin, David M.; Fairen, A.G.; Frydenvang, J.; Gasnault, O.; Gelfenbaum, Guy R.; Goetz, W.; Grotzinger, J.P.; Le Mouélic, S.; Mangold, N.; Newsom, H.; Oehler, D. Z.; Rapin, W.; Schieber, J.; Wiens, R.C.

    2017-01-01

    Since landing in Gale crater, the Mars Science Laboratory rover Curiosity has traversed fluvial, lacustrine, and eolian sedimentary rocks that were deposited within the crater ∼3.6 to 3.2 b.y. ago. Here we describe structures interpreted to be pipes formed by vertical movement of fluidized sediment. Like many pipes on Earth, those in Gale crater are more resistant to erosion than the host rock; they form near other pipes, dikes, or deformed sediment; and some contain internal concentric or eccentric layering. These structures provide new evidence of the importance of subsurface aqueous processes in shaping the near-surface geology of Mars.

  10. Quaternary volcanism, tectonics, and sedimentation in the Idaho National Engineering Laboratory area

    Energy Technology Data Exchange (ETDEWEB)

    Hackett, W.R.; Smith, R.P.

    1992-01-01

    In this article, we discuss the regional context and describe localities for a two-day field excursion in the vicinity of the Idaho National Engineering Laboratory (INEL). We address several geologic themes: (1) Late Cenozoic, bimodal volcanism of the Eastern Snake River Plain (ESRP), (2) the regional tectonics and structural geology of the Basin and Range province to the northwest of the ESRP, (3) fluvial, lacustrine, and aeolian sedimentation in the INEL area, and (4) the influence of Quaternary volcanism and tectonics on sedimentation near the INEL.

  11. Quaternary volcanism, tectonics, and sedimentation in the Idaho National Engineering Laboratory area

    Energy Technology Data Exchange (ETDEWEB)

    Hackett, W.R.; Smith, R.P.

    1992-09-01

    In this article, we discuss the regional context and describe localities for a two-day field excursion in the vicinity of the Idaho National Engineering Laboratory (INEL). We address several geologic themes: (1) Late Cenozoic, bimodal volcanism of the Eastern Snake River Plain (ESRP), (2) the regional tectonics and structural geology of the Basin and Range province to the northwest of the ESRP, (3) fluvial, lacustrine, and aeolian sedimentation in the INEL area, and (4) the influence of Quaternary volcanism and tectonics on sedimentation near the INEL.

  12. Human impacts on sediment in the Yangtze River: A review and new perspectives

    Science.gov (United States)

    Yang, H. F.; Yang, S. L.; Xu, K. H.; Milliman, J. D.; Wang, H.; Yang, Z.; Chen, Z.; Zhang, C. Y.

    2018-03-01

    Changes in riverine suspended and riverbed sediments have environmental, ecological and social implications. Here, we provide a holistic review of water and sediment transport and examine the human impacts on the flux, concentration and size of sediment in the Yangtze River in recent decades. We find that most of the fluvial sediment has been trapped in reservoirs, except for the finest portion. Furthermore, soil-conservation since the 1990s has reduced sediment yield. From 1956-1968 (pre-dam period) to 2013-2015 (post-dams and soil-conservation), the sediment discharge from the sub-basins decreased by 91%; in the main river, the sediment flux decreased by 99% at Xiangjiaba (upper reach), 97% at Yichang (transition between upper and middle reaches), 83% at Hankou (middle reach), and 77% at Datong (tidal limit). Because the water discharge was minimally impacted, the suspended sediment concentration decreased to the same extent as the sediment flux. Active erosion of the riverbed and coarsening of surficial sediments were observed in the middle and lower reaches. Fining of suspended sediments was identified along the river, which was counteracted by downstream erosion. Along the 700-km-long Three Gorges Reservoir, which retained 80% of the sediment from upstream, the riverbed gravel or rock was buried by mud because of sedimentation after impoundment. Along with these temporal variations, the striking spatial patterns of riverine suspended and riverbed sediments that were previously exhibited in this large basin were destroyed or reversed. Therefore, we conclude that the human impacts on sediment in the Yangtze River are strong and systematic.

  13. Comprehensive Sediment Management to Improve Wetland Sustainability in Coastal Louisiana

    Science.gov (United States)

    Khalil, S.; Freeman, A. M.; Raynie, R.

    2016-02-01

    Human intervention has impaired the Mississippi River's ability to deliver sediment to its deltaic wetlands, and as a consequence acute land loss in coastal Louisiana has resulted in an unprecedented ecocatastrophe. Since the 1930s, Louisiana has lost approximately 5,000 square kilometers of coastal land, and is continuing to lose land at the rate of approximately 43 square kilometers/year. This extreme rate of land loss threatens a range of key national assets and important communities. Coastal communities across the world as well as in Louisiana have realized the importance of sediment for the continuation of their very existence in these productive but vulnerable regions. Ecological restoration can only be undertaken on a stable coastline, for which sedimentological restoration is needed. A large-scale effort to restore coastal Louisiana is underway, guided by Louisiana's Comprehensive Master Plan for a Sustainable Coast. This 50-year, $50-billion plan prescribes 109 protection and restoration projects to reduce land loss, maintain and restore coastal environments and sustain communities. Nowhere else has a restoration and protection program of this scale been developed or implemented, and critical to its success is the optimized usage of limited fluvial and offshore sediment resources, and a keen understanding of the complex interactions of various geological/geophysical processes in ecosystem restoration. A comprehensive sediment management plan has been developed to identify and delineate potential sediment sources for restoration, and to provide a framework for managing sediment resources wisely, cost effectively, and in a systematic manner. The Louisiana Sediment Management Plan provides regional strategies for improved comprehensive management of Louisiana's limited sediment resources. Adaptive management via a robust system-wide monitoring plays an important role along with a regional approach for the efficient management of sediment resources.

  14. Anthropopression markers in lake bottom sediments

    Science.gov (United States)

    Nadolna, Anna; Nowicka, Barbara

    2014-05-01

    Lakes are vulnerable to various types of anthropogenic disturbances. Responses of lake ecosystems to environmental stressors are varied and depend not only on the type of a factor but also on the lake natural resistance to degradation. Within the EULAKES project an evaluation of anthropogenic stress extent in a flow-through, postglacial, ribbon lake (Lake Charzykowskie) was carried out. It was assumed, that this impact manifests unevenly, depending on a type and degree of the pressure on the shore zones, water quality of tributaries, lake basin shape and dynamics of a water movement. It was stated, that anthropogenic markers are substances accumulated in bottom sediments as a result of allochthonous substances inflow from the catchment and atmosphere. Along the selected transects 105 samples from the top layer of sediments (about 20 cm) was collected representing the contemporary accumulation (about 15 years). The content of selected chemical elements and compounds was examined, including nutrients (TN and TP), heavy metals (arsenic, cadmium, lead, chromium, nickel, copper, zinc, mercury, iron, and manganese) and pesticides (DDT, DDD, DDE, DMDT , γ-HCH). The research was conducted in the deepest points of each lake basin and along the research transects - while choosing the spots, the increased intensity of anthropogenic impact (ports, roads with heavy traffic, wastewater discharge zones, built-up areas) was taken into consideration. The river outlets to the lake, where there are ecotonal zones between limnic and fluvial environment, were also taken into account. Analysis of the markers distribution was carried out against the diversity of chemical characteristics of limnic sediments. Ribbon shape of the lake basin and the dominant wind direction provide an opportunity of easy water mixing to a considerable depth. Intensive waving processes cause removal of the matter from the littoral zone towards lake hollows (separated by the underwater tresholds), where the

  15. The effects of lithology and landsliding on hillslope sediment supply: case study from southern Italy

    Science.gov (United States)

    Roda-Boluda, Duna; D'Arcy, Mitch; Whittaker, Alex; McDonald, Jordan

    2017-04-01

    Sediment supply from hillslopes -including volumes, rates and grain size distributions- controls the sediment fluxes from upland areas and modulates how landscapes respond to tectonics. Here, we present new field data from tectonically-active areas in southern Italy that quantifies how lithology and rock-mass strength control the delivery processes and grain size distributions of sediment supplied from hillslopes. We evaluate the influence of landslides on sediment supply along 8 normal faults with excellent tectonic constraints. Frequency-area analysis of the landslide inventory, and a new field-calibrated area-volume scaling relationship, reveal that landsliding in the area is not dominated by large landslides (β ˜2), with 83% of landslides being inventory likely represents the integrated record of landsliding over 1-3 kyrs, implying minimum sediment fluxes between 6.90 x 102 and 2.07 x 103 m3/yr. We demonstrate that outcrop-scale rock-mass strength controls both landslide occurrence and the grain sizes supplied by bedrock weathering, for different lithologies. Comparisons of particle size distributions from bedrock weathering with those measured on landslide deposits demonstrates that landslides supply systematically coarser material, with lithology influencing the degree of coarsening. Finally, we evaluate the effect of landslide supply on fluvial sediment export, and show that D84 grain size increases by ˜ 6 mm for each 100-m increment in incision depth, due to the combination of enhanced landsliding and transport capacity in more incised catchments. Our results reveal a dual control of lithology and rock-mass strength on both the sediment volumes and grain sizes supplied to the fluvial system, which we demonstrate has a significant impact on sediment export from upland areas. This study provides a uniquely detailed field data set for studying how tectonics and lithology control hillslope erosion and sediment characteristics.

  16. Assessing historical sediment connectivity in a mesoscale catchment using multi-temporal aerial photographs

    Science.gov (United States)

    Llena, Manel; Cavalli, Marco; Vericat, Damià; Smith, Mark

    2017-04-01

    Land uses changes interfere on sediment production and delivery in fluvial channel networks. The study of the evolution of sediment connectivity associated with different land use changes is prerequisite for a better understanding of sediment budgets and associated processes. Previous studies examined historical changes of sediment connectivity, but most are based on indices of sediment connectivity (IC) estimated by means of: (i) a single Digital Elevation Model (DEM), usually the most recent; and (ii) a weighting factor parameter, used in IC as a proxy of the impedance to sediment fluxes, that is assessed based on land use properties. However, some structural or geomorphological elements determined by both natural processes (e.g. rock falls) and human impacts (e.g. land uses changes) may have fundamental influences on connectivity, especially in a mountain areas typically affected by mass movements and strong land crop abandonment during the 20th century. Therefore, all these elements are able to modify landscape properties and, consequently, sediment connectivity. Within this context, the objective of this work is to develop and apply a workflow to extract historical IC maps using different information that can be obtained from historical aerial photos. A prerequisite of the analysis is to reconstruct the land use and the landscape properties at the period in which the IC is estimated. The analysis consists of three interrelated steps: extraction of historical ortophotomaps and point clouds from historical photos (aerial photos from 1957 and 1977) in the Upper River Cinca (Southern Pyrenees), derivation of land use maps and topographic models for those periods, and assessment and comparison of historical sediment connectivity in contrasted sub-catchments exhibiting variable degrees of land use change. The study of changes on sediment connectivity through time may provide valuable information to understand some of the floodplain and channel adjustments that are

  17. Utilization of ancient permafrost carbon in headwaters of Arctic fluvial networks

    NARCIS (Netherlands)

    Mann, Paul J.; Eglinton, Timothy I.; McIntyre, Cameron P.; Zimov, Nikita; Davydova, Anna; Vonk, Jorien E.|info:eu-repo/dai/nl/370832833; Holmes, Robert M.; Spencer, Robert G M

    2015-01-01

    Northern high-latitude rivers are major conduits of carbon from land to coastal seas and the Arctic Ocean. Arctic warming is promoting terrestrial permafrost thaw and shifting hydrologic flowpaths, leading to fluvial mobilization of ancient carbon stores. Here we describe 14 C and 13 C

  18. On the connectivity anisotropy in fluvial Hot Sedimentary Aquifers and its influence on geothermal doublet performance

    DEFF Research Database (Denmark)

    Willems, Cees J.L.; Nick, Hamid; Donselaar, Marinus E.

    2017-01-01

    This study finds that the geothermal doublet layout with respect to the paleo flow direction in fluvial sedimentary reservoirs could significantly affect pump energy losses. These losses can be reduced by up to 10% if a doublet well pair is oriented parallel to the paleo flow trend compared...

  19. Using Mars's Sulfur Cycle to Constrain the Duration and Timing of Fluvial Processes

    Science.gov (United States)

    Blaney, D. L.

    2002-01-01

    Sulfur exists in high abundances at diverse locations on Mars. This work uses knowledge of the Martian sulfate system to discriminate between leading hypotheses and discusses the implications for duration and timing of fluvial processes. Additional information is contained in the original extended abstract.

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

    Science.gov (United States)

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

  1. Fluvial and aeolian interaction under permafrost condition: Weichselian Late Pleniglacial, Twente, Eastern Netherlands.

    NARCIS (Netherlands)

    van Huissteden, J.; Vandenberghe, J.; van der Hammen, T.; Laan, W.

    2000-01-01

    Close interaction between fluvial and aeolian deposition led to the formation of a distinct 'fluvio-aeolian' depositional environment in river valleys in the Netherlands during the last glacial maximum. We describe three sections illustrating this sedimentary environment. The primary sedimentary

  2. Mount Kenya volcanic activity and the Late Cenozoic landscape reorganisation in the upper Tana fluvial system

    NARCIS (Netherlands)

    Veldkamp, A.; Schoorl, J.M.; Wijbrans, J.R.; Claessens, L.F.G.

    2012-01-01

    Volcanic–fluvial landscape interaction of the late Cenozoic Mt Kenya region in the upper Tana catchment has been reconstructed. The oldest newly dated phonolite flow is 5.78 Ma (40Ar/39Ar), placing the initiation of Mt Kenya volcanic activity within the Late Miocene, much earlier than reported

  3. Response of the Rhine-Meuse fluvial system to Saalian ice-sheet dynamics

    NARCIS (Netherlands)

    Busschers, F.S.; Balen, R.T. van; Cohen, K.M.; Kasse, C.; Weerts, H.J.T.; Wallinga, J.; Bunnik, F.P.M.

    2008-01-01

    A new reconstruction of the interaction between the Saalian Drente glaciation ice margin and the Rhine-Meuse fluvial system is presented based on a sedimentary analysis of continuous core material, archived data and a section in an ice-pushed ridge. Optically Stimulated Luminescence (OSL) was

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

    NARCIS (Netherlands)

    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.

    2013-01-01

    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

  5. Determination of burial dose in incompletely bleached fluvial samples using single grains of quartz

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, A.S.; Bøtter-Jensen, Lars

    2007-01-01

    We determine the burial dose in three known-age incompletely bleached fluvial samples using single grains of quartz. Estimation of burial dose in incompletely bleached samples requires that the characteristics of the well-bleached part of the distribution are known in order to distinguish between...

  6. Erfkroon: a new Florisian fossil locality from fluvial contexts in the western Free State, South Africa

    CSIR Research Space (South Africa)

    Churchill, SE

    2000-04-01

    Full Text Available This article provides information on a research on Erfkroon, a Florisian fossil locality from fluvial contexts in the western Free State of South Africa. As well as details on the excavation of gravel bars at the locality; Complexity of the geology...

  7. The Amazonian Craton and its influence on past fluvial systems (Mesozoic-Cenozoic, Amazonia)

    NARCIS (Netherlands)

    Hoorn, C.; Roddaz, M.; Dino, R.; Soares, E.; Uba, C.; Ochoa-Lozano, D.; Mapes, R.; Hoorn, C.; Wesselingh, F.P.

    2010-01-01

    The Amazonian Craton is an old geological feature of Archaean/Proterozoic age that has determined the character of fluvial systems in Amazonia throughout most of its past. This situation radically changed during the Cenozoic, when uplift of the Andes reshaped the relief and drainage patterns of

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

    Science.gov (United States)

    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 ...

  9. Holocene sediment distribution on the inner continental shelf of northeastern South Carolina: implications for the regional sediment budget and long-term shoreline response

    Science.gov (United States)

    Denny, Jane F.; Schwab, William C.; Baldwin, Wayne E.; Barnhardt, Walter A.; Gayes, Paul T.; Morton, R.A.; Warner, John C.; Driscoll, Neal W.; Voulgaris, George

    2013-01-01

    High-resolution geophysical and sediment sampling surveys were conducted offshore of the Grand Strand, South Carolina to define the shallow geologic framework of the inner shelf. Results are used to identify and map Holocene sediment deposits, infer sediment transport pathways, and discuss implications for the regional coastal sediment budget. The thickest deposits of Holocene sediment observed on the inner shelf form shoal complexes composed of moderately sorted fine sand, which are primarily located offshore of modern tidal inlets. These shoal deposits contain ~67 M m3 of sediment, approximately 96% of Holocene sediment stored on the inner shelf. Due to the lack of any significant modern fluvial input of sand to the region, the Holocene deposits are likely derived from reworking of relict Pleistocene and older inner-shelf deposits during the Holocene marine transgression. The Holocene sediments are concentrated in the southern part of the study area, due to a combination of ancestral drainage patterns, a regional shift in sediment supply from the northeast to the southwest in the late Pleistocene, and proximity to modern inlet systems. Where sediment is limited, only small, low relief ridges have formed and Pleistocene and older deposits are exposed on the seafloor. The low-relief ridges are likely the result of a thin, mobile veneer of sediment being transported across an irregular, erosional surface formed during the last transgression. Sediment textural trends and seafloor morphology indicate a long-term net transport of sediment to the southwest. This is supported by oceanographic studies that suggest the long-term sediment transport direction is controlled by the frequency and intensity of storms that pass through the region, where low pressure systems yield net along-shore flow to the southwest and a weak onshore component. Current sediment budget estimates for the Grand Strand yield a deficit for the region. Volume calculations of Holocene deposits on the

  10. Holocene construction and evolution of the Ganges-Brahmaputra-Meghna delta: the influence of climate, eustasy, and tectonics on stratigraphic architecture and fluvial dynamics

    Science.gov (United States)

    Sincavage, R.; Goodbred, S. L., Jr.; Pickering, J.; Wilson, C.; Patrick, M. G.; Akhter, S. H.; Seeber, L.; Paola, C.; Jean-Louis, G.; Grall, C.

    2015-12-01

    The Ganges-Brahmaputra-Meghna delta (GBMD), an archetypal tidally-influenced deltaic margin, has been the subject of several multi-national, multi-institutional, and interdisciplinary field studies over the past several years, resulting in an unprecedented density of data coverage for stratigraphy, hydrodynamics, and tectonics on a scale previously only found on well-studied delta systems of other types (e.g., Nile, Mississippi, Rhine-Meuse). Using a suite of geochemical, geophysical, and lithologic data extracted from a network of over 400 shallow (course along the eastern edge of the Tista Fan and west of the modern confluence with the Ganges. Construction of the modern delta, consisting of a thick (up to 80 m) succession of fluvial and deltaic sediments, was initiated by an intensified summer monsoon, coincident with accommodation generated by rapid sea-level rise following the Younger-Dryas. Sediment delivery has been focused along three pathways associated with antecedent topography inherited from Pleistocene lowstands. Stacked channel sands are the predominant facies within the upper delta, grading to isolated sand lenses in the distal reaches of Sylhet Basin, indicative of a shift from a highly mobile braidbelt to a less mobile distributary system as bedload is extracted to deposition. Episodic avulsions of the Brahmaputra River into Sylhet Basin during the mid-Holocene have been documented using a robust radiocarbon geochronology. The volume of sediment preserved from these events is insufficient to account for the entire sediment budget based on estimates of modern discharge, likely a consequence of both a weakened mid-Holocene monsoon and bypass out of the basin. Rapid (up to 7 mm/yr) subsidence in Sylhet Basin has not acted as an attractor for channel steering during much of the Holocene. Instead, the Brahmaputra has followed the steepest descent path associated with flexural loading downstream of the hinge zone along the modern braidbelt.

  11. Hillslope failure and paraglacial reworking of sediments in response to glacier retreat, Fox Valley, New Zealand.

    Science.gov (United States)

    McColl, Samuel T.; Fuller, Ian C.; Anderson, Brian; Tate, Rosie

    2017-04-01

    Climate and glacier fluctuations influence sediment supply to glacier forelands, which in turn influences down-valley hazards to infrastructure and tourism within glacier forelands. At Fox Glacier, one of New Zealand's most iconic and popular glaciers, rapid retreat has initiated a range of hillslope and valley floor responses, that present a cascade of hazards and changes that need to be carefully managed. Fox Glacier has retreated many kilometres historically, with 2.6 km of retreat since the mid-20th century, and a phase of rapid retreat of 50-340 m per year since 2009. To study the system response to past and ongoing glacial retreat at the Fox valley, morphological changes are being observed using time-lapse photography and the annual collection of high-resolution digital elevation models (DEMs) and orthophoto mosaics. The DEMs are being produced using Structure from Motion photogrammetry from UAV/RPAS and helicopter platforms, and are being used, along with manual ground surveying, to produce ground surface change models (DoDs; DEMs of Difference) and sediment budgets for the valley. Results from time-lapse photography and DoDs show that glacial retreat has initiated destabilisation and (mostly chronic) mass movement of surficial glacial sediments on the valley slopes near the glacier terminus. Alluvial fans farther down valley are actively growing, reworking glacial and landslide sediments from tributary catchments. These paraglacial sediments being delivered to the proglacial river from the glacier terminus and alluvial fans are driving aggradation of the valley floor of decimetres to metres per year and maintaining a highly dynamic braid plain. Valley floor changes also include the melting of buried dead ice, which are causing localised subsidence at the carpark and one of the alluvial fans. The unstable slopes and active debris fans, aggrading and highly active river channel, ground subsidence, add to the spectacle but also the hazards of the Fox valley

  12. Distribution of heavy metals in sediments of ligurian coastal areas

    Energy Technology Data Exchange (ETDEWEB)

    Picollo, A.; Frache, R.; Magi, E.; Ianni, C. [Genua Univ., Genua (Italy). Dept. of Chemistry and Industrial Chemistry

    2000-08-01

    A study on the concentration and distribution of heavy metals (Zn, Pb, Fe, Cr, V, Mn, Cu) in the sediments of the Ligurian coast was carried out. The data are interpreted by the Principal Component Analysis and related, for Cr and Fe, to the fluvial sediments. The comparison between the data obtained from the present study and similar matrices of Mediterranean coastal environment has allowed the determination of values due chiefly to natural input. [Italian] Il lavoro riguarda la distribuzione e la concentrazione di alcuni metalli pesanti (Zn, Pb, Fe, Cr, V, Mn, Cu) nei sedimenti costieri della Liguria. I dati ottenuti sono stati interpretati con l'ausilio dell'analisi delle componenti principali (PCA) e i valori di concentrazione del Cr e del Fe sono risultati correlati agli apporti fluviali. Il confronto tra i dati ottenuti con matrici similari di ambienti costieri del Mediterraneo ha permesso di riscontrare valori dovuti principalmente ad apporti naturali.

  13. Textural features of the beach sediments of Wast Water Lake, Northwest England

    Directory of Open Access Journals (Sweden)

    Bala Emilia

    2016-06-01

    Full Text Available This study is dedicated to Wast Water Lake (Northwest England, Great Britain and the character of its beach sediments. The aim of the study is to identify the textural features of the lake’s beach sediments based on two methods. The first is a granulometric analysis and the second a pebble shape analysis according to Zingg (1935 and Sneed & Folk (1958. Both analyses were carried out for all of the lake’s accessible beaches and the cliffs adjacent to them. The transport and deposition history of the examined sediments was identified through field research and laboratory analysis. The results show that the textural features of the sediments at Wast Water are more often typical of a fluvial environment, rather than having been changed by lacustrine water movements.

  14. Evolution and preservation potential of fluvial and transgressive deposits on the Louisiana inner shelf: Understanding depositional processes to support coastal management

    Science.gov (United States)

    Flocks, J.; Miner, M.D.; Twichell, D.C.; Lavoie, D.L.; Kindinger, J.

    2009-01-01

    The barrier-island systems of the Mississippi River Delta plain are currently undergoing some of the highest rates of shoreline retreat in North America (???20 m/year). Effective management of this coastal area requires an understanding of the processes involved in shoreline erosion and measures that can be enacted to reduce loss. The dominant stratigraphy of the delta plain is fluvial mud (silts and clays), delivered in suspension via a series of shallow-water delta lobes that prograded across the shelf throughout the Holocene. Abandonment of a delta lobe through avulsion leads to rapid land subsidence through compaction within the muddy framework. As the deltaic headland subsides below sea level, the marine environment transgresses the bays and wetlands, reworking the available sands into transgressive barrier shorelines. This natural process is further complicated by numerous factors: (1) global sea-level rise; (2) reduced sediment load within the Mississippi River; (3) diversion of the sediment load away from the barrier shorelines to the deep shelf; (4) storm-induced erosion; and (5) human alteration of the littoral process through the construction of hardened shorelines, canals, and other activities. This suite of factors has led to the deterioration of the barrier-island systems that protect interior wetlands and human infrastructure from normal wave activity and periodic storm impact. Interior wetland loss results in an increased tidal prism and inlet cross-sectional areas, and expanding ebb-tidal deltas, which removes sand from the littoral processes through diversion and sequestration. Shoreface erosion of the deltaic headlands does not provide sufficient sand to balance the loss, resulting in thinning and dislocation of the islands. Abatement measures include replenishing lost sediment with similar material, excavated from discrete sandy deposits within the muddy delta plain. These sand bodies were deposited by the same cyclical processes that formed the

  15. Hyporheic zone as a bioreactor: sediment heterogeneity influencing biogeochemical processes

    Science.gov (United States)

    Perujo, Nuria; Romani, Anna M.; Sanchez-Vila, Xavier

    2017-04-01

    Mediterranean fluvial systems are characterized by frequent periods of low flow or even drought. During low flow periods, water from wastewater treatment plants (WWTPs) is proportionally large in fluvial systems. River water might be vertically transported through the hyporheic zone, and then porous medium acts as a complementary treatment system since, as water infiltrates, a suite of biogeochemical processes occurs. Subsurface sediment heterogeneity plays an important role since it influences the interstitial fluxes of the medium and drives biomass growing, determining biogeochemical reactions. In this study, WWTP water was continuously infiltrated for 3 months through two porous medium tanks: one consisting of 40 cm of fine sediment (homogeneous); and another comprised of two layers of different grain size sediments (heterogeneous), 20 cm of coarse sediment in the upper part and 20 cm of fine one in the bottom. Several hydrological, physicochemical and biological parameters were measured periodically (weekly at the start of the experiment and biweekly at the end). Analysed parameters include dissolved nitrogen, phosphorus, organic carbon, and oxygen all measured at the surface, and at 5, 20 and 40 cm depth. Variations in hydraulic conductivity with time were evaluated. Sediment samples were also analysed at three depths (surface, 20 and 40 cm) to determine bacterial density, chlorophyll content, extracellular polymeric substances, and biofilm function (extracellular enzyme activities and carbon substrate utilization profiles). Preliminary results suggest hydraulic conductivity to be the main driver of the differences in the biogeochemical processes occurring in the subsurface. At the heterogeneous tank, a low nutrient reduction throughout the whole medium is measured. In this medium, high hydraulic conductivity allows for a large amount of infiltrating water, but with a small residence time. Since some biological processes are largely time-dependent, small water

  16. Fingerprinting of bed sediment in the Tay Estuary, Scotland: an environmental magnetism approach

    Directory of Open Access Journals (Sweden)

    P. A. Jenkins

    2002-01-01

    Full Text Available Sediment fingerprinting is commonly used for sediment provenance studies in lakes, rivers and reservoirs and on hillslopes and floodplains. This investigation explores the mixing of terrestrial and marine-derived sediment in the Tay Estuary, Scotland, using mineral magnetic attributes for fingerprinting. Samples representative of the estuary sediments and of four sources (end-members were subjected to a suite of magnetic susceptibility and remanence measurements. Sediment samples from the beds of the Rivers Tay and Earn represented fluvial inputs while samples from the Angus and Fife coasts represented marine input. Multivariate discriminant and factor analysis showed that the sources could be separated on the basis of six magnetic parameters in a simple multivariate unmixing model to identify source contributions to estuarine bed sediments. Multi-domain magnetite signatures, characteristic of unweathered bedrock, dominate the magnetic measurements. Overall contributions of 3% from the River Earn, 17% from the River Tay, 29% from the Angus coast and 51% from the Fife coast source end-members, demonstrated the present-day regime of marine sediment derivation in the Tay Estuary. However, this conceals considerable spatial variability both along-estuary and in terms of sub-environments, with small-scale variations in sediment provenance reflecting local morphology, particularly areas of channel convergence. Keywords: bed sediment, environmental magnetism, fingerprinting, Tay Estuary, Scotland

  17. What role do hurricanes play in sediment delivery to subsiding river deltas?

    Science.gov (United States)

    Smith, James E.; Bentley, Samuel J.; Snedden, Gregg; White, Crawford

    2015-01-01

    The Mississippi River Delta (MRD) has undergone tremendous land loss over the past century due to natural and anthropogenic influences, a fate shared by many river deltas globally. A globally unprecedented effort to restore and sustain the remaining subaerial portions of the delta is now underway, an endeavor that is expected to cost $50–100B over the next 50 yr. Success of this effort requires a thorough understanding of natural and anthropogenic controls on sediment supply and delta geomorphology. In the MRD, hurricanes have been paradoxically identified as both substantial agents of widespread land loss, and vertical marsh sediment accretion. We present the first multi-decadal chronostratigraphic assessment of sediment supply for a major coastal basin of the MRD that assesses both fluvial and hurricane-induced contributions to sediment accumulation in deltaic wetlands. Our findings indicate that over multidecadal timescales, hurricane-induced sediment delivery may be an important contributor for deltaic wetland vertical accretion, but the contribution from hurricanes to long-term sediment accumulation is substantially less than sediment delivery supplied by existing and planned river-sediment diversions at present-day river-sediment loads.

  18. Sediment cascade modelling for stochastic torrential sediment transfers forecasting in a changing alpine climate

    Science.gov (United States)

    Rudaz, Benjamin; Bardou, Eric; Jaboyedoff, Michel

    2015-04-01

    Alpine ephemeral streams act as links between high altitude erosional processes, slope movements and valley-floor fluvial systems or fan storage. Anticipating future mass wasting from these systems is crucial for hazard mitigation measures. Torrential activity is highly stochastic, with punctual transfers separating long periods of calm, during which the system evolves internally and recharges. Changes can originate from diffuse (rock faces, sheet erosion of bared moraines), concentrated external sources (rock glacier front, slope instabilities) or internal transfers (bed incision or aggradation). The proposed sediment cascade model takes into account those different processes and calculates sediment transfer from the slope to the channel reaches, and then propagates sediments downstream. The two controlling parameters are precipitation series (generated from existing rain gauge data using Gumbel and Extreme Probability Distribution functions) and temperature (generated from local meteorological stations data and IPCC scenarios). Snow accumulation and melting, and thus runoff can then be determined for each subsystem, to account for different altitudes and expositions. External stocks and sediment sources have each a specific response to temperature and precipitation. For instance, production from rock faces is dependent on frost-thaw cycles, in addition to precipitations. On the other hand, landslide velocity, and thus sediment production is linked to precipitations over longer periods of time. Finally, rock glaciers react to long-term temperature trends, but are also prone to sudden release of material during extreme rain events. All those modules feed the main sediment cascade model, constructed around homogeneous torrent reaches, to and from which sediments are transported by debris flows and bedload transport events. These events are determined using a runoff/erosion curve, with a threshold determining the occurrence of debris flows in the system. If a debris

  19. Architecture and sediment dynamics of the Mauritania Slide Complex

    Energy Technology Data Exchange (ETDEWEB)

    Henrich, Ruediger; Hanebuth, Till J.J.; Krastel, Sebastian [Faculty of Geosciences, University of Bremen, P.O. Box 330440, D-28334 Bremen (Germany); Neubert, Nadja [Faculty of Geosciences, University of Bremen, P.O. Box 330440, D-28334 Bremen (Germany); Institut fuer Geologie, Universitaet Bern, Baltzerstrasse 1-3, Bern (Switzerland); Wynn, Russell B. [National Oceanography Centre, European Way, Southampton, Hampshire, SO14 3ZH (United Kingdom)

    2008-01-15

    Large-scale mass wasting is an important sedimentary process along the northwest African margin, and is related to high sediment accumulation rates under an ocean margin upwelling regime. Although the margin is generally arid with limited fluvial input, additional sediment supply comes from wind-borne Saharan dust. Recent mapping of the margin off Mauritania has revealed a major sediment slide, here called the Mauritania Slide Complex, as it comprises elements of true sliding as well as more mobile distal debris flow. Seismic data image stacked slide deposits separated by undisturbed stratified sediments indicating that undisturbed sediment accumulation was interrupted by several phases of slope failure. A series of stepped headwalls, 25-100 m high, represents the source area of the youngest slide event, which most likely occurred as retrogressive type of failure. The area of seafloor affected by this mass movement is {proportional_to}30,000 km{sup 2}, while the deposit volume is {proportional_to}600 km{sup 3}. The uppermost debrite unit, which has been {sup 14}C dated at 10.5-10.9 ka, forms a broad tongue extending down to the lower slope. This debrite comprises a vertical succession of three different layers of matrix types, with a predominantly outer shelf source at the base and pelagite-dominated composition at the top. The complete sequence of three layers was deposited at a mid slope position, whereas only the upper layers reached the lower slope. A thick pile of sediments with outer shelf/upper slope derived biogenic and terrigenous debris-rich sediments at the base and hemipelagic sediments on top failed at an upper to mid slope location and disintegrated into a layered debris flow on its down-slope journey. (author)

  20. Diachronic 3D modelling to monitor fluvial morphodynamics in a restored hydrosystem (Upper Rhine, Rohrschollen island)

    Science.gov (United States)

    Koehl, Mathieu; Eschbach, David; Grussenmeyer, Pierre; Schmitt, Laurent; Guillemin, Samuel

    2017-04-01

    The Rohrschollen artificial island is a Natural Reserve located 8 km South-East the city of Strasbourg. The island results from several engineering works (correction and canalization) lead on the reach since the beginning of the 19th century to improve flood control, agriculture, navigation and to produce hydropower. Consequently, the main channel of the island (called old channel) was upstream disconnected, hydromorphological functioning was altered (narrowing and clogging, decreasing of morphodynamics and of surface water-groundwater exchanges…) and specific alluvial biodiversity declined drastically. In the framework of a LIFE+ European program, an ambitious restoration project was carried out by the city of Strasbourg with the aims to restore hydromorphological dynamics and improve typical ecological characteristics of the hydrosystem: bedload dynamics, channel mobility, surface water-groundwater exchanges and renewal of pioneer ecosystems… To achieve these objectives, a new upstream channel was dug in the floodplain and a large floodgate was built in order to reconnect the old channel with the Rhine. Water input is about 2 m3.s-1 and could attain a maximum of 80 m3.s-1 during Rhine's floods. This new hydrological dynamics allowed to recover dynamic floods and high morphological activities, especially on the new channel which was intentionally undersized. As part of the partnership between the LIVE laboratory and the INSA of Strasbourg, a monitoring of fluvial morphodynamics was carried out, based on a diachronic 3D modelling survey. Focused on three bending sectors of the channel, the initial state was realized in 2014, before the first flood, by a geo-referenced 3D model recorded by Terrestrial Laser Scanning (TLS) and panoramic images. This method was used as a 3D digital reference model and setup by differential GNSS techniques. The long-term diachronic monitoring was based on terrestrial photogrammetry surveys followed by dense matching techniques

  1. Palaeoenvironments during a terminal Oligocene or early Miocene transgression in a fluvial system at the southwestern tip of Africa

    Science.gov (United States)

    Roberts, D. L.; Neumann, F. H.; Cawthra, H. C.; Carr, A. S.; Scott, L.; Durugbo, E. U.; Humphries, M. S.; Cowling, R. M.; Bamford, M. K.; Musekiwa, C.; MacHutchon, M.

    2017-03-01

    A multi-proxy study of an offshore core in Saldanha Bay (South Africa) provides new insights into fluvial deposition, ecosystems, phytogeography and sea-level history during the late Paleogene-early Neogene. Offshore seismic data reveal bedrock topography, and provide evidence of relative sea levels as low as - 100 m during the Oligocene. 3D landscape reconstruction reveals hills, plains and an anastomosing river system. A Chattian or early Miocene age for the sediments is inferred from dinoflagellate taxa Distatodinium craterum, Chiropteridium lobospinosum, Homotryblium plectilum and Impagidinium paradoxum. The subtropical forest revealed by palynology includes lianas and vines, evergreen trees, palms and ferns, implying higher water availability than today, probably reduced seasonal drought and stronger summer rainfall. From topography, sedimentology and palynology we reconstruct Podocarpaceae-dominated forests, Proto-Fynbos, and swamp/riparian forests with palms and other angiosperms. Rhizophoraceae present the first South African evidence of Palaeogene/Neogene mangroves. Subtropical woodland-thicket with Combretaceae and Brachystegia (Peregrinipollis nigericus) probably developed on coastal plains. Some of the last remaining Gondwana elements on the sub-continent, e.g., Araucariaceae, are recorded. Charred particles signal fires prior to the onset of summer dry climate at the Cape. Marine and terrestrial palynomorphs, together with organic and inorganic geochemical proxy data, suggest a gradual glacio-eustatic transgression. The data shed light on Southern Hemisphere biogeography and regional climatic conditions at the Palaeogene-Neogene transition. The proliferation of the vegetation is partly ascribed to changes in South Atlantic oceanographic circulation, linked to the closure of the Central American Seaway and the onset of the Benguela Current 14 Ma.

  2. Evolution of Early Pleistocene fluvial systems in central Poland prior to the first ice sheet advance - a case study from the Bełchatów lignite mine

    Science.gov (United States)

    Goździk, Jan; Zieliński, Tomasz

    2017-06-01

    Deposits formed between the Neogene/Pleistocene transition and into the Early Pleistocene have been studied, mainly on the basis of drillings and at rare, small outcrops in the lowland part of Polish territory. At the Bełchatów lignite mine (Kleszczów Graben, central Poland), one of the largest opencast pits in Europe, strata of this age have long been exposed in extensive outcrops. The present paper is based on our field studies and laboratory analyses, as well as on research data presented by other authors. For that reason, it can be seen as an overview of current knowledge of lowermost Pleistocene deposits at Bełchatów, where exploitation of the Quaternary overburden has just been completed. The results of cartographic work, sedimentological, mineralogical and palynological analyses as well as assessment of sand grain morphology have been considered. All of these studies have allowed the distinction of three Lower Pleistocene series, i.e., the Łękińsko, Faustynów and Krzaki series. These were laid down in fluvial environments between the end of the Pliocene up to the advance of the first Scandinavian ice sheet on central Poland. The following environmental features have been interpreted: phases of river incision and aggradation, changes of river channel patterns, source sediments for alluvia, rates of aeolian supply to rivers and roles of fluvial systems in morphological and geological development of the area. The two older series studied, i.e., Łękińsko and Faustynów, share common characteristics. They were formed by sinuous rivers in boreal forest and open forest environments. The Neogene substratum was the source of the alluvium. The younger series (Krzaki) formed mainly in a braided river setting, under conditions of progressive climatic cooling. Over time, a gradual increase of aeolian supply to the fluvial system can be noted; initially, silt and sand were laid down, followed by sand only during cold desert conditions. These fluvio

  3. Investigating the use of the dual-polarized and large incident angle of SAR data for mapping the fluvial and aeolian deposits

    Science.gov (United States)

    Gaber, Ahmed; Amarah, Bassam A.; Abdelfattah, Mohamed; Ali, Sarah

    2017-12-01

    Mapping the spatial distributions of the fluvial deposits in terms of particles size as well as imaging the near-surface features along the non-vegetated aeolian sand-sheets, provides valuable geological information. Thus this work aims at investigating the contribution of the dual-polarization SAR data in classifying and mapping the surface sediments as well as investigating the effect of the radar incident-angle on improving the images of the hidden features under the desert sand cover. For mapping the fluvial deposits, the covariance matrix ([C2]) using four dual-polarized ALOS/PALSAR-1 scenes cover the Wadi El Matulla, East Qena, Egypt were generated. This [C2] matrix was used to generate a supervised classification map with three main classes (gravel, gravel/sand and sand). The polarimetric scattering response, spectral reflectance and temperatures brightness of these 3 classes were extracted. However for the aeolian deposits investigation, two Radarsat-1 and three full-polarimetric ALOS/PALSAR-1 images, which cover the northwestern sandy part of Sinai, Egypt were calibrated, filtered, geocoded and ingested in a GIS database to image the near-surface features. The fluvial mapping results show that the values of the radar backscattered coefficient (σ°) and the degree of randomness of the obtained three classes are increasing respectively by increasing their grain size. Moreover, the large incident angle (θi = 39.7) of the Radarsat-1 image has revealed a meandering buried stream under the sand sheet of the northwestern part of Sinai. Such buried stream does not appear in the other optical, SRTM and SAR dataset. The main reason is the enhanced contrast between the low backscattered return from the revealed meandering stream and the surroundings as a result of the increased backscattering intensity, which is related to the relatively large incident angle along the undulated surface of the study area. All archaeological observations support the existence of

  4. Latest Holocene Mapping of Tsunamigenically- and Seismogenically-Influenced Beach, Dune and Fluvial Landforms at Tolowa Dunes State Park, Northwestern California

    Science.gov (United States)

    Vaughan, P. R.

    2015-12-01

    Beach, dune, fluvial, and marine terrace deposits comprise a 16 kilometer (km) coastal strip immediately south of the Smith River at Tolowa Dunes State Park (TDSP), ~ 3.5 km north-northwest from downtown Crescent City, California. The park has numerous Native American sites that are vulnerable to sea level rise and coastal erosion, part of which may be influenced by Cascadia interseismic deformation. Efforts at removal of exotic beach grass (Ammophila arenaria) that stabilizes most of the dune complex have begun; vegetation removal will remobilize the dunes and could obscure and also expose near surficial geologic features. Using a LiDAR base to capture extant data and give context to future resource protection projects, I surficially mapped the dunes and provisionally interpreted, tsunamigenically-derived cobbles (which are more than five feet thick in one road cut exposure) that extensively mantle the deflation plain in the lee of the foredune. Natural, test pit and auger exposures helped characterize fluvial and marsh deposits in the southern bank and floodplain of the Smith River. Optically stimulated luminescence and/or radiocarbon dates constrain the ages for cobble deposits and dunes throughout the park, and liquefaction features exposed in the southern bank of the Smith River. In combination with estimated rates of dune formation and migration at TDSP since the A.D. 1700 Cascadia earthquake, the ages for seismogenically-sourced sediment associated with dune ridges and cobble deposits are tentatively correlated with the ages of latest Holocene Cascadia triggered turbidites dated by Goldfinger et al. (2012) on the Smith River platform. The mapping also helped identify a marine terrace sequence on the southern limb of the northwest-trending Lake Earl Syncline that bifurcates the park, and suggests projection of the northwest-trending Cemetery Scarp, part of the Point St. George fault complex (Polenz and Kelsey 1999), through the southern part of the park.

  5. The spatial distribution of arsenic contamination in fluvial sediment of the Ganges River : Case study from Bihar, India

    NARCIS (Netherlands)

    Donselaar, M.E.; Bhatt, A.G.; Bruining, J.; Bose, N.; Ghosh, A.K.

    2013-01-01

    Shallow aquifers in the Ganges River channel belt (Bihar, India) have high and spatially variable concentrations of arsenic contamination. The arsenic is of geogenic origin. Hydrated iron-arsenic-oxide coatings on quartz and clay minerals occur in the Ganges River deposits. The arsenic is

  6. Magnitude and extent of the impact of a small-scale gold-mine on the geochemistry of stream bed and floodplain sediments in the Horsefly catchment, British Columbia, Canada

    NARCIS (Netherlands)

    van der Perk, Marcel|info:eu-repo/dai/nl/074715437; Vogels, Marjolein F. A.|info:eu-repo/dai/nl/413534960; Clark, Deirdre E.; Owens, Philip N.; Petticrew, Ellen L.

    2014-01-01

    Mining represents a major source of metal contamination for fluvial systems worldwide. Monitoring and understanding the effects on downstream water and sediment quality is essential for effective management of active and abandoned mine sites. This study aims to determine the downstream effects of

  7. How environmental magnetism can enhance the interpretational value of grain-size analysis: A time-slice study on sediment export to the NW African margin in Heinrich Stadial 1 and Mid Holocene

    NARCIS (Netherlands)

    Razik, S.; Dekkers, M.J.|info:eu-repo/dai/nl/073463744; Von Dobeneck, T.

    2014-01-01

    Sediment dynamics in limnic, fluvial and marine environments can be assessed by granulometric and rock-magnetic methodologies. While classical grain-size analysis by sieving or settling mainly bears information on composition and transport, the magnetic mineral assemblages reflect to a larger extent

  8. Dinosaur tracks in Lower Jurassic coastal plain sediments (Sose Bugt Member, Rønne Formation) on Bornholm, Denmark

    DEFF Research Database (Denmark)

    Clemmensen, Lars B; Milàn, Jesper; Pedersen, Gunver K

    2014-01-01

    Fluvial palaeochannels of coastal plain sediments of the Lower Jurassic Sose Bugt Member of the Rønne Formation exposed in the coastal cliffs at Sose Bugt, Bornholm, contain abundant dinosaur or other large vertebrate tracks in the form of deformation structures exposed in vertical section...... track. Contemporary Upper Triassic – Lower Jurassic strata from southern Sweden and Poland contain a diverse track fauna, supporting our interpretation. This is the earliest evidence of dinosaur activity in Denmark....

  9. The missing piece: sediment records in remote Mountain lakes confirm glaciers being secondary sources of persistent organic pollutants.

    Science.gov (United States)

    Schmid, Peter; Bogdal, Christian; Blüthgen, Nancy; Anselmetti, Flavio S; Zwyssig, Alois; Hungerbühler, Konrad

    2011-01-01

    After atmospheric deposition and storage in the ice, glaciers are temporary reservoirs of persistent organic pollutants (POPs). Recently, the hypothesis that melting glaciers represent secondary sources of these pollutants has been introduced by investigations of the historical trend of POPs in a dated sediment core from the proglacial Alpine Lake Oberaar. Here, the hypothesis is further confirmed by the comparison of sediment data gathered from two Alpine lakes with a glaciated and a nonglaciated hydrological catchment. The two lakes (Lake Engstlen and Lake Stein in the Bernese Alps in Switzerland) are situated only 8 km apart at similar altitude and in the same meteorological catchment. In the nonglacial lake sediment of Lake Engstlen, PCBs and DDT (polychlorinated biphenyls and dichlorodiphenyl trichloroethane) levels culminated with the historic usage of these chemicals some 30-50 years ago. In the glacial Lake Stein, this peak was followed by a reincrease in the 1990s, which goes along with the accelerated melting of the adjacent glacier. This study confirms the hypothesis of glaciers being a secondary source of these pollutants and is in accordance with the earlier findings in Lake Oberaar.

  10. Rock magnetic properties of sediments from Lake Sanabria and its catchment (NW Spain): paleoenvironmental implications

    Science.gov (United States)

    Larrasoaña, J. C.; Borruel, V.; Gómez-Paccard, M.; Rico, M.; Valero-Garces, B.; Moreno-Caballud, A.; Soto, R.

    2013-12-01

    Lake Sanabria is located in the NW Spanish mountains at 1000 m a.s.l., and constitutes the largest lake of glacial origin in the Iberian Peninsula. Here we present an environmental magnetic study of a Late Pleistocene-Holocene sediment core from Lake Sanabria and from different lithologies that crop out in its catchment, which includes Paleozoic plutonic, metamorphic and vulcanosedimentary rocks, and Quaternary deposits of glacial origin. This study was designed to complement sedimentologic and geochemical studies aimed at unraveling the climatic evolution of the NW Iberian Peninsula during the last deglaciation. Our results indicate that magnetite and pyrrhotite dominate the magnetic assemblage of both the sediments from the lower half of the studied sequence (25.6 - 13 cal kyr BP) deposited in a proglacial environment, and the Paleozoic rocks that make up most of the catchment of the lake. The occurrence of these minerals both in the catchment rocks and in the lake sediments indicates that sedimentation was then driven by the erosion of a glacial flour, which suffered minimal chemical transformation in response to a rapid and short routing to the lake. Sediments from the upper half of the studied sequence, accumulated after 12.4 cal kyr BP in a fluviolacustrine environment, contain magnetite and greigite. This points to a prominent role of post-depositional reductive dissolution, driven by a sharp increase in the accumulation of organic matter into the lake and the creation of anoxic conditions in the sediments, in shaping the magnetic assemblage of Holocene sediments. Pyrrhotite is stable under reducing conditions as opposed to magnetite, which is unstable. We therefore interpret that previous pedogenic processes occurred in the then deglaciated catchment of the lake were responsible for the oxidation of pyrrhotite and authigenic formation of magnetite, which survived subsequent reductive diagenesis given its initial larger concentrations. This interpretation is

  11. Estuary-wide genetic stock distribution and salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  12. Global Catalogue of the Martian Valley Networks: Evidences for Fluvial, Sapping and Subglacial Processes on Early Mars

    Science.gov (United States)

    Grau Galofre, A.; Jellinek, A. M.

    2017-10-01

    We use erosion models and statistical morphometry schemes to show quantitative evidence for fluvial, glacial, groundwater sapping and subglacial erosion on the Noachian highlands, to then build a global map of valley network origin and distribution.

  13. Effects of fluvial processes in different order river valleys on redistribution and storage of particle-bound radioactive caesium-137 in area of significant Chernobyl fallout and impact on linked rivers with lower contamination levels

    Science.gov (United States)

    Belyaev, Vladimir; Golosov, Valentin; Shamshurina, Evgeniya; Ivanov, Maxim; Ivanova, Nadezhda; Bezukhov, Dmitry; Onda, Yuichi; Wakiyama, Yoshifumi; Evrard, Olivier

    2015-04-01

    Detailed investigations of the post-fallout fate of radionuclide contamination represent an important task in terms of environmental quality assessment. In addition, particle-bound radionuclides such as the most widespread anthropogenic isotope caesium-137 can be used as tracers for quantitative assessment of different sediment redistribution processes. In landscapes of humid plains with agriculture-dominated land use the post-fallout redistribution of caesium-137 is primarily associated with fluvial activity of various scales in cascade systems starting from soil erosion on cultivated hillslopes through gully and small dry valley network into different order perennial streams and rivers. Our investigations in the so-called Plavsk hotspot (area of very high Chernobyl caesium-137 contamination within the Plava River basin, Tula Region, Central European Russia) has been continuing for more than 15 years by now, while the time passed since the Chernobyl disaster and associated radioactive fallout (1986) is almost 29 years. Detailed information on the fluvial sediment and associated caesium-137 redistribution has been obtained for case study sites of different size from individual cultivated slopes and small catchments of different size (2-180 km2) to the entire Plava River basin scale (1856 km2). It has been shown that most of the contaminated sediment over the time passed since the fallout has remained stored within the small dry valleys of the 1-4 Hortonian order and local reservoirs (>70%), while only about 5% reached the 5-6 order valleys (main tributaries of the Plava River) and storage of the Plava floodplain itself represents as low as 0.3% of the basin-scale total sediment production from eroded cultivated hillslopes. Nevertheless, it has been shown that contaminated sediment yield from the Plava River basin exerts significant influence on less polluted downstream-linked river system. Recent progress of the investigations involved sampling of 7 detailed depth

  14. Aeolian particle transport inferred using a ~150-year sediment record from Sayram Lake, arid northwest China

    Directory of Open Access Journals (Sweden)

    Long Ma

    2015-05-01

    Full Text Available We studied sediment cores from Sayram Lake in the Tianshan Mountains of northwest China to evaluate variations in aeolian transport processes over the past ~150 years. Using an end-member modeling algorithm of particle size data, we interpreted end members with a strong bimodal distribution as having been transported by aeolian processes, whereas other end members were interpreted to have been transported by fluvial processes. The aeolian fraction accounted for an average of 27% of the terrigenous components in the core. We used the ratio of aeolian to fluvial content in the Sayram Lake sediments as an index of past intensity of aeolian transport in the Tianshan Mountains. During the interval 1910-1930, the index was high, reflecting the fact that dry climate provided optimal conditions for aeolian dust transport. From 1930-1980, the intensity of aeolian transport was weak. From the 1980s to the 2000s, aeolian transport to Sayram Lake increased. Although climate in northwest China became more humid in the mid-1980s, human activity had by that time altered the impact of climate on the landscape, leading to enhanced surface erosion, which provided more transportable material for dust storms. Comparison of the Lake Sayram sediment record with sediment records from other lakes in the region indicates synchronous intervals of enhanced aeolian transport from 1910 to 1930 and 1980 to 2000.

  15. Acoustic architecture of glaciolacustrine sediments deformed during zonal stagnation of the Laurentide Ice Sheet; Mazinaw Lake, Ontario, Canada

    Science.gov (United States)

    Eyles, Nicholas; Doughty, Mike; Boyce, Joseph I.; Mullins, Henry T.; Halfman, John D.; Koseoglu, Berkant

    2003-03-01

    In North America, the last (Laurentide) Ice Sheet retreated from much of the Canadian Shield by 'zonal stagnation'. Masses of dead ice, severed from the main ice sheet by emerging bedrock highs, downwasted in situ within valleys and lake basins and were commonly buried by sediment. Consequently, the flat sediment floors of many valleys and lakes are now pitted by steep-sided, enclosed depressions (kettle basins) that record the melt of stagnant ice blocks and collapse of sediment. At Mazinaw Lake in eastern Ontario, Canada, high-resolution seismic reflection, magnetic and bathymetric surveys, integrated with onland outcrop and hammer seismic investigations, were conducted to identify the types of structural disturbance associated with the formation of kettle basins in glaciolacustrine sediments. Basins formed as a result of ice blocks being trapped within a regionally extensive proglacial lake (Glacial Lake Iroquois ˜12,500 to 11,400 years BP) that flooded eastern Ontario during deglaciation. Kettles occur within a thick (>30 m) succession of parallel, high-frequency acoustic facies consisting of rhythmically laminated (varved?) Iroquois silty-clays. Iroquois strata underlying and surrounding kettle basins show large-scale normal faults, fractures, rotational failures and incoherent chaotically bedded sediment formed by slumping and collapse. Mazinaw Lake lies along part of the Ottawa Graben and while neotectonic earthquake activity cannot be entirely dismissed, deformation is most likely to have occurred as a result of the rapid melt of buried ice blocks. Seismic data do not fully penetrate the entire basin sediment fill but the structure and topography of bedrock can be inferred from magnetometer data. The location and shape of buried ice masses was closely controlled by the graben-like form of the underlying bedrock surface.

  16. High-resolution multitemporal measurement of rockglacier dynamics and periglacial sediment storage in the eastern Alps, Austria

    Science.gov (United States)

    Dusik, Jana-Marie; Haas, Florian; Heckmann, Tobias; Hilger, Ludwig; Neugirg, Fabian; Leopold, Matthias; Becht, Michael

    2013-04-01

    High alpine environments are subject to rapid change due to melting glaciers and permafrost. As a consequence, rockwalls and moraines experience destabilization and increased mobilization of sediment. The work presented here is part of the joint project PROSA (High-resolution measurements of morphodynamics in rapidly changing PROglacial Systems of the Alps) which deals with the calculation and quantification of the sediment budget for an alpine catchment situated in the Kaunertal, Austrian Alps. Rockglaciers are frequently appearing landforms in the Kaunertal and represent large sediment storages. Usually the sediment flux of rockglaciers is rather small, depending on their activity status. All activity forms of rockglaciers (active, inactive and relict) are present in the catchment area. Besides the highly active and well-known Ölgrube rockglacier, this work deals especially with the examination of the Riffeltal rockglacier which is situated on the opposite valley side. The activity status of the Riffeltal rockglacier is assessed and compared to the Ölgrube rockglacier with respect to the local parameters aspect, altitude, existence/absence of glaciers, geology and catchment area. Furthermore sediment volumes of both rockglaciers, their rates of movement and therefore their contribution to the sediment budget of the Kaunertal-catchment area is estimated. The internal structure of the Riffeltal rockglacier was inferred from geophysical measurements (refraction seismics, ground penetrating radar and electrical resistivity tomography). Temperature loggers were placed on and around the rockglacier before the first snowfall to measure the bottom temperature of snowcover (BTS) once per hour during winter, and BTS measurements will be performed with a probe in February, March and April to infer permafrost probability. Rockglacier dynamics are identified with the analysis of multitemporal orthophotos and digital elevation models, derived from high-resolution airborne

  17. Sedimentology of the Essaouira Basin (Meskala Field) in context of regional sediment distribution patterns during upper Triassic pluvial events

    Science.gov (United States)

    Mader, Nadine K.; Redfern, Jonathan; El Ouataoui, Majid

    2017-06-01

    Upper Triassic continental clastics (TAGI: Trias Argilo-Greseux Inferieur) in the Essaouira Basin are largely restricted to the subsurface, which has limited analysis of the depositional environments and led to speculation on potential provenance of the fluvial systems. Facies analysis of core from the Meskala Field onshore Essaouira Basin is compared with tentatively time-equivalent deposits exposed in extensive outcrops in the Argana Valley, to propose a process orientated model for local versus regional sediment distribution patterns in the continuously evolving Moroccan Atlantic rift during Carnian to Norian times. The study aims to unravel the climatic overprint and improve the understanding of paleo-climatic variations along the Moroccan Atlantic margin to previously recognised Upper Triassic pluvial events. In the Essaouira Basin, four facies associations representing a progressive evolution from proximal to distal facies belts in a continental rift were established. Early ephemeral braided river systems are succeeded by a wet aeolian sandflat environment with a strong arid climatic overprint (FA1). This is followed by the onset of perennial fluvial deposits with extensive floodplain fines (FA2), accompanied by a distinct shift in fluvial style, suggesting increase in discharge and related humidity, either locally or in the catchment area. The fluvial facies transitions to a shallow lacustrine or playa lake delta environment (FA3), which exhibits cyclical abandonment. The delta is progressively overlain by a terminal playa with extensive, mottled mudstones (FA4), interpreted to present a return from cyclical humid-arid conditions to prevailing aridity in the basin. In terms of regional distribution and sediment source provenance, paleocurrent data from Carnian to Norian deposits (T5 to T8 member) in the Argana Valley suggest paleoflow focused towards the S and SW, not directed towards the Meskala area in the NW as previously suggested. A major depo

  18. Tratamiento de los espacios fluviales urbanos andaluces en la planificación territorial y sectorial

    Directory of Open Access Journals (Sweden)

    David González Rojas

    2017-01-01

    Full Text Available La recuperación y conservación de los espacios fluviales urbanos debe insertarse dentro de los procesos de planificación territorial y sectorial. El presente trabajo analiza la evolución y las transformaciones de los espacios fluviales urbanos en Andalucía durante las últimas décadas, a través del análisis de los distintos planes. Para el estudio de las relaciones entre el planeamiento territorial y sectorial y los espacios fluviales urbanos se ha realizado una recopilación de los documentos actualmente aprobados o en tramitación. En el artículo se destacan los avances durante el periodo estudiado, pero también las inercias, resistencias y nuevos problemas asociados. El esfuerzo realizado para la ordenación de los ríos a su paso por las ciudades no ha tenido su reflejo en los resultados obtenidos, siendo las interrelaciones entre la gestión del agua y del territorio (regional, subregional y municipal una cuestión no resuelta.

  19. Pemaknaan Filsafati Kearifan Lokal untuk Adaptasi Masyarakat terhadap Ancaman Bencana Marin dan Fluvial di Lingkungan Kepesisiran

    Directory of Open Access Journals (Sweden)

    S Sunarto

    2011-07-01

    Full Text Available The purpose of this research was to study the philosophical meaning of local wisdom that developed in the communities in the coastal environment, particularly in the eastern coast of Central Java. The method used for this philosophical meaning using the approach of geomorphological hermeneutics and disaster semiotics. The results of this research indicate that identified local wisdom in the form of cultural semiotics and faunal semiotics to anticipate the hazards of climate change as marine hazard and fluvial hazard. Cultural semiotics found in the form of advice that still need to be interpreted with a geomorphological hermeneutics approach order to use it to adapt to the coastal environment against marine hazard. The cultural semiotics has a geomorphological philosophical meaning as natural cycle that leads to dynamic equilibrium, not the philosophical meaning that leads to the view of anthropocentrism. In addition, also found cultural semiotics of “Dina Rèntèng” based on the philosophical views of ecocentrism. The cultural semiotics is used in society to adapt to the fluvial hazard. Faunal semiotics found in the form of anomalous crab behavior as a form of adaptation due to its response to environmental condition. The faunal semiotics has been used as a guide for the community to adapt to the fluvial hazard. Because of the local wisdom is loaded with philosophical meaning, it can be metatourism assets, so it can convert harm into benefit.

  20. The Ephemeral Signature of Permafrost Carbon in an Arctic Fluvial Network

    Science.gov (United States)

    Spencer, R. G.; Drake, T.; Guillemette, F.; Chanton, J.; Podgorski, D. C.; Zimov, N.

    2016-12-01

    Arctic fluvial networks process, outgas, and transport significant quantities of terrestrial organic carbon (OC). The contribution from permafrost thaw, however, remains uncertain. A primary obstacle to quantifying the contribution of permafrost OC is its high biodegradability, since it is lost to microbial respiration soon after thaw. In this study, we investigate the by-product of respiration (dissolved inorganic carbon; DIC) at maximum late-summer thaw in sites spanning the fluvial network in order to assess whether the microbial consumption of permafrost imparts a persisting aged (14C-depleted) signature on the DIC pool. Using keeling-curve incubations, we show that water column bacteria respire different sources of dissolved OC (DOC) downstream. Evidence of permafrost respiration (production of aged DIC) was only present in permafrost-influenced sites. In the non-permafrost sites, ambient DIC was modern, which does not preclude respiration of permafrost OC upstream since depleted 14C in DIC can be easily overwhelmed by modern (14C-enriched) DIC. DOC compositional analysis via FT-ICR-MS showed that aliphatic and nitrogen containing compounds were associated with the production of aged DIC, which provides insight as to why permafrost OC is likely rapidly respired upon thaw. Overall, the results from this study demonstrate the complications of using 14C-DIC as a geochemical tracer for permafrost. We highlight the need for novel and unique conservative geochemical tracers to quantify the release and fate of permafrost OC in fluvial systems.

  1. Comparison of sediment supply to San Francisco Bay from watersheds draining the Bay Area and the Central Valley of California

    Science.gov (United States)

    McKee, L.J.; Lewicki, M.; Schoellhamer, D.H.; Ganju, N.K.

    2013-01-01

    Quantifying suspended sediment loads is important for managing the world's estuaries in the context of navigation, pollutant transport, wetland restoration, and coastal erosion. To address these needs, a comprehensive analysis was completed on sediment supply to San Francisco Bay from fluvial sources. Suspended sediment, optical backscatter, velocity data near the head of the estuary, and discharge data obtained from the output of a water balance model were used to generate continuous suspended sediment concentration records and compute loads to the Bay from the large Central Valley watershed. Sediment loads from small tributary watersheds around the Bay were determined using 235 station-years of suspended sediment data from 38 watershed locations, regression analysis, and simple modeling. Over 16 years, net annual suspended sediment load to the head of the estuary from its 154,000 km2 Central Valley watershed varied from 0.13 to 2.58 (mean = 0.89) million metric t of suspended sediment, or an average yield of 11 metric t/km2/yr. Small tributaries, totaling 8145 km2, in the nine-county Bay Area discharged between 0.081 and 4.27 (mean = 1.39) million metric t with a mean yield of 212 metric t/km2/yr. The results indicate that the hundreds of urbanized and tectonically active tributaries adjacent to the Bay, which together account for just 5% of the total watershed area draining to the Bay and provide just 7% of the annual average fluvial flow, supply 61% of the suspended sediment. The small tributary loads are more variable (53-fold between years compared to 21-fold for the inland Central Valley rivers) and dominated fluvial sediment supply to the Bay during 10 out of 16 yr. If San Francisco Bay is typical of other estuaries in active tectonic or climatically variable coastal regimes, managers responsible for water quality, dredging and reusing sediment accumulating in shipping channels, or restoring wetlands in the world's estuaries may need to more carefully

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

    Science.gov (United States)

    Reheis, M.C.

    1992-01-01

    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.

  3. Fingerprinting of bed sediment in the Tay Estuary, Scotland: an environmental magnetism approach

    Science.gov (United States)

    Jenkins, Pierre A.; Duck, Rob W.; Rowan, John S.; Walden, John

    Sediment fingerprinting is commonly used for sediment provenance studies in lakes, rivers and reservoirs and on hillslopes and floodplains. This investigation explores the mixing of terrestrial and marine-derived sediment in the Tay Estuary, Scotland, using mineral magnetic attributes for fingerprinting. Samples representative of the estuary sediments and of four sources (end-members) were subjected to a suite of magnetic susceptibility and remanence measurements. Sediment samples from the beds of the Rivers Tay and Earn represented fluvial inputs while samples from the Angus and Fife coasts represented marine input. Multivariate discriminant and factor analysis showed that the sources could be separated on the basis of six magnetic parameters in a simple multivariate unmixing model to identify source contributions to estuarine bed sediments. Multi-domain magnetite signatures, characteristic of unweathered bedrock, dominate the magnetic measurements. Overall contributions of 3% from the River Earn, 17% from the River Tay, 29% from the Angus coast and 51% from the Fife coast source end-members, demonstrated the present-day regime of marine sediment derivation in the Tay Estuary. However, this conceals considerable spatial variability both along-estuary and in terms of sub-environments, with small-scale variations in sediment provenance reflecting local morphology, particularly areas of channel convergence.

  4. Late Holocene Shoreline Dynamics and Sediment Partitioning in the Waipaoa Sedimentary System, New Zealand

    Science.gov (United States)

    Wolinsky, M. A.; Swenson, J. B.; Bever, A.; Harris, C. K.

    2006-12-01

    Over the course of the late Holocene highstand the shoreline at Poverty Bay has actively prograded due to sediment influx from the Waipaoa river. Mapping of paleo-shoreline positions has shown that the progradation rate has decreased through time. We use sedimentary process modeling on multiple time scales to evaluate potential causes of this decrease, and to constrain long-term sediment fluxes entering the coastal plain and exiting Poverty Bay. We consider three factors which could potentially contribute to the decelerating progradation: (1) Increasing basin width as the shoreline progrades seaward, (2) decreasing sediment supply to the shore due to upstream decreases in erosion or increases in storage, and (3) increasing sediment removal from the nearshore as the shoreline approaches the mouth of Poverty Bay and the coast becomes less sheltered from energetic waves. Simplified (1D diffusive) long-term stratigraphic modeling of the fluvial system is used to explore the effects of variations in upstream sediment and water supply on floodplain storage and shoreline progradation. We use a detailed 3D hydrodynamic model of sediment transport by waves and currents to explore the fate of sediment which reaches the shore. Results from these 3D simulations of single flood and storm events are scaled up to constrain the partitioning of sediment between the nearshore and outer shelf.

  5. From agricultural intensification to conservation: Sediment transport in the Raccoon River, Iowa, 1916-2009

    Science.gov (United States)

    Jones, C.S.; Schilling, K.E.

    2011-01-01

    Fluvial sediment is a ubiquitous pollutant that negatively aff ects surface water quality and municipal water supply treatment. As part of its routine water supply monitoring, the Des Moines Water Works (DMWW) has been measuring turbidity daily in the Raccoon River since 1916. For this study, we calibrated daily turbidity readings to modern total suspended solid (TSS) concentrations to develop an estimation of daily sediment concentrations in the river from 1916 to 2009. Our objectives were to evaluate longterm TSS patterns and trends, and relate these to changes in climate, land use, and agricultural practices that occurred during the 93-yr monitoring period. Results showed that while TSS concentrations and estimated sediment loads varied greatly from year to year, TSS concentrations were much greater in the early 20th century despite drier conditions and less discharge, and declined throughout the century. Against a backdrop of increasing discharge in the Raccoon River and widespread agricultural adaptations by farmers, sediment loads increased and peaked in the early 1970s, and then have slowly declined or remained steady throughout the 1980s to present. With annual sediment load concentrated during extreme events in the spring and early summer, continued sediment reductions in the Raccoon River watershed should be focused on conservation practices to reduce rainfall impacts and sediment mobilization. Overall, results from this study suggest that eff orts to reduce sediment load from the watershed appear to be working. ?? 2011 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

  6. What are the contemporary sources of sediment in the Mississippi River?

    Science.gov (United States)

    Hassan, M. A.; Roberge, L.; Church, M.; More, M.; Donner, S. D.; Leach, J.; Ali, K. F.

    2017-09-01

    Within the last two centuries, the Mississippi River basin has been transformed by changes in land use practices, dam construction, and training of the rivers for navigation. Here we analyze the contemporary patterns of fluvial sediment yield in the Mississippi River basin using all available data in order to assess the influence of regional land condition on the variation of sediment yield within the basin. We develop regional-scale relations between specific sediment yield (yield per unit area) and drainage area to reveal contemporary regional sediment yield patterns and source areas of riverine sediments. Extensive upland erosion before the development of soil conservation practices exported large amounts of sediment to the valleys and floodplains. We show that sediment today is sourced primarily along the river valleys from arable land, and from stream bank and channel erosion, with sediment yields from areas dominated by arable land 2 orders of magnitude greater than that of grassland dominated areas. Comparison with the "T factor," a commonly quoted measure of agricultural soil resilience suggests that the latter may not reflect contemporary soil loss from the landscape.

  7. Dispersal and transport of river sediment on the Catalan Shelf (NW Mediterranean Sea).

    Science.gov (United States)

    Grifoll, Manel; Gracia, Vicente; Espino, Manuel; Sánchez-Arcilla, Agustín

    2014-05-01

    A three-dimensional coupled hydrodynamics-sediment transport model for the Catalan shelf (NW Mediterranean Sea) is implemented and used to represent the fluvial sediment transport and depositional patterns. The modelling system COAWST (Warner et al., 2010) allows to exchange field from the water circulation model ROMS and the wave model SWAN including combined wave-current bed stress and both sediment transport mechanisms: bed and suspended load. Two rivers surrounding Barcelona harbour are considered in the numerical experiments. Different temporal and spatial scales are modelled in order to evaluate physical mechanisms such as: fine deposits formation in the inner-shelf, harbour siltation or sediment exporting to the outer shelf. Short-time simulations in a high-resolution mesh have been used to reproduce the initial stages of the sediment dispersal. In this case, sediment accumulation occurs confined in an area attached to the coastline. A subsequent reworking is observed due to the wave-induced bottom stresses which resuspend fine material exported then towards the mid-shelf by seawards fluxes. The long-term water circulation simulations explains the observed fine deposits over the shelf. The results provide knowledge of sediment transport processes in the near-shore area of a micro-tidal domain. REFERENCES: Warner, J.C., Armstrong, B., He, R., and Zambon, J.B., 2010, Development of a Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system: Ocean Modeling, v. 35, no. 3, p. 230-244.

  8. Linking Late Pleistocene alpine glacial erosion and continental margin sedimentation: Insights from 40Ar/39Ar dating of silt-sized sediment, Canterbury Basin, New Zealand

    Science.gov (United States)

    Villaseñor, Tania; Jaeger, John M.; Foster, David A.

    2016-01-01

    Quaternary climatic and eustatic cycles in mid-latitude regions have led to more extensive alpine glaciations and continental shelf progradation, respectively. However, the glacial influence on sediment fluxes to the ocean creating continental margin strata is poorly documented. This contribution analyzes the provenance of fine sediment accumulating on the continental shelf during the Late Pleistocene to evaluate the influence of glacial cycles on sediment erosion and routing to the continental shelf. Taking advantage of the contrasting bedrock ages exposed across the Southern Alps, New Zealand, we perform 40Ar/39Ar incremental heating on the bulk silt-size sediment from three drill sites of IODP Expedition 317, Canterbury Basin, New Zealand. The results suggest that a large proportion of sediment accumulating on the continental shelf results from erosion within the Main Divide fault zone of the Southern Alps. Sediment 40Ar/39Ar age fluctuations over this time period suggest that bedrock with various 40Ar/39Ar cooling ages has been differentially eroded in the upper Waitaki River catchment and mixed in the Waitaki-Canterbury sediment-routing system. Across-shelf variations in sediment 40Ar/39Ar age reflect changing modes of sediment dispersal on the continental shelf. Fluvial material, likely derived from the main drainage divide zone, preferentially accumulates in the middle continental shelf, whereas material representing erosion of older bedrock (Torlesse Terrane), located lower in the drainage basin, is dispersed uniformly across the shelf. The age signature of the muddy sediment accumulating on the continental shelf reflects Late Pleistocene landscape evolution of the Southern Alps and its influence on sediment dispersal to the continental shelf.

  9. Sediment contributions from floodplains and legacy sediments to Piedmont streams of Baltimore County, Maryland

    Science.gov (United States)

    Donovan, Mitchell; Miller, Andrew; Baker, Matthew; Gellis, Allen C.

    2015-01-01

    Disparity between watershed erosion rates and downstream sediment delivery has remained an important theme in geomorphology for many decades, with the role of floodplains in sediment storage as a common focus. In the Piedmont Province of the eastern USA, upland deforestation and agricultural land use following European settlement led to accumulation of thick packages of overbank sediment in valley bottoms, commonly referred to as legacy deposits. Previous authors have argued that legacy deposits represent a potentially important source of modern sediment loads following remobilization by lateral migration and progressive channel widening. This paper seeks to quantify (1) rates of sediment remobilization from Baltimore County floodplains by channel migration and bank erosion, (2) proportions of streambank sediment derived from legacy deposits, and (3) potential contribution of net streambank erosion and legacy sediments to downstream sediment yield within the Mid-Atlantic Piedmont.We calculated measurable gross erosion and deposition rates within the fluvial corridor along 40 valley segments from 18 watersheds with drainage areas between 0.18 and 155 km2 in Baltimore County, Maryland. We compared stream channel and floodplain morphology from lidar-based digital elevation data collected in 2005 with channel positions recorded on 1:2400 scale topographic maps from 1959–1961 in order to quantify 44–46 years of channel change. Sediment bulk density and particle size distributions were characterized from streambank and channel deposit samples and used for volume to mass conversions and for comparison with other sediment sources.Average annual lateral migration rates ranged from 0.04 to 0.19 m/y, which represented an annual migration of 2.5% (0.9–4.4%) channel width across all study segments, suggesting that channel dimensions may be used as reasonable predictors of bank erosion rates. Gross bank erosion rates varied from 43 to 310 Mg/km/y (median = 114) and

  10. Sediment transport and erosional processes of a mountain bedrock channel using high-resolution topographic surveys

    Science.gov (United States)

    Yin, Yu-Hsuan; Shyu, J. Bruce H.

    2017-04-01

    In recent years, spatial information with high resolution and accuracy have become widely available, thanks to the rapid technological developments. Such data have been applied in a variety of topics, including the digitization and monitoring of outcrops and the construction of digital elevation models (DEMs) of landscapes. In fluvial geomorphology, it is critical to understand the sediment transport and erosional processes of bedrock channels, but previously this is generally done using computer numerical simulations or minimized experiments. Therefore, this study intends to observe in situ fluvial sediment transport and erosional processes using terrestrial laser scanning (also called "ground LiDAR") and structure-from-motion (SfM) photogrammetry in a mountain bedrock channel in eastern Taiwan. Along the Swallow Grotto (Yanzikou) section of the Liwu River, there are many large boulders with different sizes that are up to more than ten meters. Most of these boulders came from rock fall events of a nearby tributary, and are gneiss in composition, distinctively different from the bedrock of the river channel (marble). Thus in this study, we chose these boulders as our survey targets. We applied ground LiDAR survey to observe the movement of the boulders, and to understand the transportation threshold of sediments under different flow conditions. For those giant boulders that do not seem to be moveable under regular fluvial conditions, we suspect that bedrock erosional processes apply to them. We then used SfM photogrammetry to monitor the erosion of particular boulders. By constructing 3D models of the boulders before and after flooding events, we will be able to analyze the amount and location of erosion occurred on the boulders. Combining these different datasets and results, we hope to further understand the sediment transport and erosional processes of bedrock channels.

  11. A field experiment on the controls of sediment transport on bedrock erosion

    Science.gov (United States)

    Beer, A. R.; Turowski, J. M.; Fritschi, B.; Rieke-Zapp, D.; Campana, L.; Lavé, J.

    2012-12-01

    The earth`s surface is naturally shaped by interactions of physical and chemical processes. In mountainous regions with steep topography river incision fundamentally controls the geomorphic evolution of the whole landscape. There, erosion of exposed bedrock sections by fluvial sediment transport is an important mechanism forming mountain river channels. The links between bedload transport and bedrock erosion has been firmly established using laboratory experiments. However, there are only few field datasets linking discharge, sediment transport, impact energy and erosion that can be used for process understanding and model evaluation. To fill this gap, a new measuring setup has been commissioned to raise an appropriate simultaneous dataset of hydraulics, sediment transport and bedrock erosion at high temporal and spatial resolution. Two natural stone slabs were installed flush with the streambed of the Erlenbach, a gauged stream in the Swiss Pre-Alps. They are mounted upon force sensors recording vertical pressure und downstream shear caused by passing sediment particles. The sediment transport rates can be assessed using geophone plates and an automated moving basket system taking short-term sediment samples. These devices are located directly downstream of the stone slabs. Bedrock erosion rates are measured continuously with erosion sensors at sub-millimeter accuracy at three points on each slab. In addition, the whole slab topography is surveyed with photogrammetry and a structured-light 3D scanner after individual flood events. Since the installation in 2011, slab bedrock erosion has been observed during several transport events. We discuss the relation between hydraulics, bedload transport, resulting pressure forces on the stone slabs and erosion rates. The aim of the study is the derivation of an empirical process law for fluvial bedrock erosion driven by moving sediment particles.

  12. Bottom Boundary Layer Sediment Transport Processes in Fourleague Bay of Louisiana and Their Implication to Sediment Diversion and Coastal Restoration

    Science.gov (United States)

    Wang, J.; Xu, K.; Bentley, S. J.; Restreppo, G. A.

    2016-02-01

    Building land with a rising sea is a challenging problem in many major deltaic systems around the world. The Atchafalaya deltaic area is one of only a few growing sites in Louisiana coast. The sediment delivered to this deltaic area is mainly from three reservoirs: (1) sediment derived from ongoing fluvial delivery; (2) mobile sediment delivered to the coastal basin during the past year by cold fronts, tropical cyclones, and others; (3) more consolidated sediment stored in the seabed or bay floor for more than 12 months. In order to better understand the far-field dispersal and deposition of fine sediments in the Atchafalaya system, two tripods were used to study the hydrodynamics and sediment dynamics at two stations in Fourleague Bay, which are 15 km southeast of Atchafalaya Delta. One tripod was located at the middle of the bay, and the other was near the marsh edge. Six sensors including OBS (Optical Backscatter Sensor) 3A, OBS 5+, ADV (Acoustic Doppler Velocimeter) Ocean, Argonaut ADV, and two wave gauges were planned to deploy in the early summer and winter of 2015 for a month, respectively. Our study was focused on the near-bed sediment transport from each of the above three reservoirs to wetlands under fair weather and event condition. Based on the seasonal surface suspended sediment concentration (SSC), salinity, as well as turbidity, wave and current data, we have investigated the bottom boundary layer sediment dynamics, in order to illustrate sediment deposition and erosion processes under fair weather and energetic conditions in the bay. During an energetic event in early summer 2015, strong southeasterly wind waves carried salty water from inner Louisiana shelf northwestward into the bay, and led to increasing wave height, bottom shear stress, salinity, and near-bed turbidity. After the event, there was apparent decreasing of these parameters. SSC data in the bay showed an increasing trend since April, which is probably related to the fine sediment

  13. Sources of suspended-sediment flux in streams of the chesapeake bay watershed: A regional application of the sparrow model

    Science.gov (United States)

    Brakebill, J.W.; Ator, S.W.; Schwarz, G.E.

    2010-01-01

    We describe the sources and transport of fluvial suspended sediment in nontidal streams of the Chesapeake Bay watershed and vicinity. We applied SPAtially Referenced Regressions on Watershed attributes, which spatially correlates estimated mean annual flux of suspended sediment in nontidal streams with sources of suspended sediment and transport factors. According to our model, urban development generates on average the greatest amount of suspended sediment per unit area (3,928 Mg/km2/year), although agriculture is much more widespread and is the greatest overall source of suspended sediment (57 Mg/km2/year). Factors affecting sediment transport from uplands to streams include mean basin slope, reservoirs, physiography, and soil permeability. On average, 59% of upland suspended sediment generated is temporarily stored along large rivers draining the Coastal Plain or in reservoirs throughout the watershed. Applying erosion and sediment controls from agriculture and urban development in areas of the northern Piedmont close to the upper Bay, where the combined effects of watershed characteristics on sediment transport have the greatest influence may be most helpful in mitigating sedimentation in the bay and its tributaries. Stream restoration efforts addressing floodplain and bank stabilization and incision may be more effective in smaller, headwater streams outside of the Coastal Plain. ?? 2010 American Water Resources Association. No claim to original U.S. government works.

  14. The fate of residual carbon in floodplain sediments, originating from eroding peatlands

    Science.gov (United States)

    Alderson, Danielle; Evans, Martin; Rothwell, James; Boult, Stephen; Rhodes, Edward

    2016-04-01

    Fluvial systems and their associated sediments have been overlooked as part of global carbon budgets until recently. In the UK, large stores of organic carbon in peatlands are dynamically eroding, with the eventual result being 'off-site' greenhouse gas emissions, which must be incorporated into carbon budgets for management strategies. Evans et al. (2013) concluded peatland fluvial systems are active cyclers of carbon, with 50-90% of particulate organic carbon (POC) exported from peatlands eventually emitted as CO2. Floodplains, although commonly regarded as zones of carbon storage, have been identified as potential hotspots of carbon cycling in the fluvial system with a key process being decomposition of POC. Only 20% of POC may escape mineralisation on floodplains within a peatland catchment (Evans et al., 2013), but studying the composition of the residual carbon has the potential to add to understanding of the drivers of storage versus mineralisation. In this research we have examined stratigraphic records of carbon cycling by focusing on organic matter preserved in a floodplain environment downstream of the Bleaklow Plateau in the Peak District. An OSL date of 640 +/- 90 years BP and a radiocarbon date of 500-310 cal years BP from the sediment cores collected, together with an assessment of the valley morphology using high resolution LiDAR DEM's, indicate potential interaction of post glacial landslide features with the onset of substantial peat erosion, conditioning the landscape to interrupt the transport of carbon down the fluvial network. Floodplain cores have been correlated on the basis of both visual stratigraphy and geochemistry obtained by Itrax core scanning. This data is supported by targeted gas flux data from boreholes using a Gasclam. We present a rudimentary carbon budget for the floodplain of study.

  15. Fluvial organic carbon losses from oil palm plantations on tropical peat, Sarawak, Southeast Asia

    Science.gov (United States)

    Cook, Sarah; Page, Susan; Evans, Chris; Whelan, Mick; Gauci, Vincent; Lip Khoon, Kho

    2017-04-01

    Tropical peatlands are valuable stores of carbon. However, tropical peat swamp forests (TPSFs) in Southeast Asia have increasingly been converted to other land-uses. For example, more than 25% of TPSFs are now under oil palm plantations. This conversion - requiring felling and burning of trees and drainage of the peat - can enhance carbon mineralization, dissolved organic carbon (DOC) losses and can contribute significantly to global anthropogenic greenhouse gas emissions, changing these natural carbon sinks into carbon sources. At present, relatively few scientifically sound studies provide dependable estimates of gaseous and fluvial carbon losses from oil palm plantations or from drained tropical peat in general. Here we present an annual (54 week) estimate of the export of dissolved and particulate organic carbon in water draining two oil palm estates and nearby stands of TPSF in Sarawak, Malaysia, subjected to varying degrees of past anthropogenic disturbance. Spectrophotometric techniques including SUVA254 (Specific Ultra-Violet Absorption) were used to gain insight into the aromaticity and subsequent bioavailability of the exported DOC. Water draining plantation and deforested land had a higher proportion of labile carbon compared to water draining forested areas. Preliminary data suggest a total fluvial DOC flux from plantations of ca. 190 g C m-2 year-1; nearly three times estimates from intact TPSFs (63 g C m-2 year-1). DOC accounted for between 86 % - 94 % of the total organic carbon lost (most of which was bioavailable). Wit et al. (2015) estimates that an average of 53 % of peat-derived DOC is decomposed and emitted as CO2, on a monthly basis. Based on these estimates our data suggests an additional 101 g CO2 m-2 may be emitted indirectly from fluvial organic carbon in degraded TPSFs per year. Overall, these findings emphasize the importance of including fluvial organic carbon fluxes when quantifying the impact of anthropogenic disturbance on the

  16. Rapid anthropogenic response to short-term aeolian-fluvial palaeoenvironmental changes during the Late Pleistocene-Holocene transition in the northern Negev Desert, Israel

    Science.gov (United States)

    Roskin, Joel; Katra, Itzhak; Agha, Nuha; Goring-Morris, A. Nigel; Porat, Naomi; Barzilai, Omry

    2014-09-01

    Archaeological investigations along Nahal Sekher on the eastern edge of Israel's northwestern Negev Desert dunefield revealed concentrations of Epipalaeolithic campsites associated respectively with ancient water bodies. This study, aimed at better understanding the connections between these camps and the water bodies, is concerned with a cluster of Natufian sites. A comprehensive geomorphological study integrating field mapping, stratigraphic sections, sedimentological analysis and optically stimulated luminescence (OSL) ages was conducted in the vicinity of a recently excavated Natufian campsite of Nahal Sekher VI whose artifacts directly overlay aeolian sand dated by OSL to 12.4 ± 0.7 and 11.7 ± 0.5 ka. Residual sequences of diagnostic silty sediments, defined here as low-energy fluvial fine-grained deposits (LFFDs), were identified within the drainage system of central Nahal Sekher around the Nahal Sekher VI site. LFFD sections were found to represent both shoreline and mid-water deposits. The thicker mid-water LFFD deposits (15.7 ± 0.7-10.7 ± 0.5 ka) date within the range of the Epipalaeolithic campsites, while the upper and shoreline LFFD units that thin out into the sands adjacent to the Nahal Sekher VI site display slightly younger ages (10.8 ± 0.4 ka-7.6 ± 0.4 ka). LFFD sedimentation by low-energy concentrated flow and standing-water developed as a result of proximal downstream dune-damming. These water bodies developed as a result of encroaching sand that initially crossed central Nahal Sekher by 15.7 ± 0.7 ka and probably intermittently blocked the course of the wadi. LFFD deposition was therefore a response to a unique combination of regional sand supply due to frequent powerful winds and does not represent climate change in the form of increased precipitation or temperature change. The chronostratigraphies affiliate the Natufian sites to the adjacent ancient water bodies. These relations reflect a rapid, but temporary anthropogenic response to a

  17. Center for Contaminated Sediments

    Data.gov (United States)

    Federal Laboratory Consortium — The U.S. Army Corps of Engineers Center for Contaminated Sediments serves as a clearinghouse for technology and expertise concerned with contaminated sediments. The...

  18. Superfund: Contaminated Sediments

    Science.gov (United States)

    Contaminated sediments are a significant environmental problem and contribute to the over 3,200 fish consumption advisories nationwide. The Superfund program cleans up sediment sites that present an unacceptable risk to human health or the environment.

  19. Indicators: Sediment Enzymes

    Science.gov (United States)

    Sediment enzymes are proteins that are produced by microorganisms living in the sediment or soil. They are indicators of key ecosystem processes and can help determine which nutrients are affecting the biological community of a waterbody.

  20. Ocean Sediment Thickness Contours

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ocean sediment thickness contours in 200 meter intervals for water depths ranging from 0 - 18,000 meters. These contours were derived from a global sediment...

  1. National Geochemical Database: Sediment

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Geochemical analysis of sediment samples from the National Geochemical Database. Primarily inorganic elemental concentrations, most samples are of stream sediment in...

  2. Time-Correlative Recovery of Milankovitch-Scale Cyclicity From An Eocene Fluvial-Deltaic System, Southern Pyrenees, Spain

    Science.gov (United States)

    Anastasio, D. J.; Kodama, K. P.; Teletzke, A. L.; Boulton, S.; Bilardello, D.

    2012-12-01

    Given the controversial state of cyclostratigraphy and the important contributions it provides to the construction of the geologic time scale it is important to know what processes encode environmental changes and what data sets best preserve the integrity of the stratigraphic signal. We test cyclostratigraphy based on rock magnetic data to calibrate time at sub-magnetic chron scales to reconstruct a ~100 kilometer-long transect of an ancient fluvial-deltaic system. Rock magnetic data provides an objective record of multi-frequency cyclicity we interpret to be climate cycles preserved in the Tertiary Ainsa-Jaca-Pamplona Basins. Anhysteretic Remanent Magnetization (ARM) from rocks dominated with low coercivity magnetite and Fe-sulfides and Isothermal Remanent Magnetization (IRM) from rocks dominated by high coercivity hematite and goethite shows the potential to trace correlative beds from terrestrial watersheds to the deep marine basin across facies boundaries. The fluvial Escanilla Fm.-Campodarbe Gp. along the Eripol-Olson section varies from sheet sandstones and overbank siltstone to amalgamated gravels up-section, is 910 m long, records chrons C19r to C15n, and was deposited at a rate of 14cm/kyr. A modified S-ratio, which takes advantage of the differences in coercivities of goethite and hematite was used to assess relative mineral abundance and shows variations in the ratio of goethite : goethite + hematite concentrations around the frequencies expected for short eccentricity (~100 kyr) and obliquity (~40 kyr). A 5 T field saturation IRM (SIRM) was first applied followed by alternating field (af) demagnetization in a 100 mT field (=goethite + hematite concentration), followed by the application of a 1 T backfield and 100 mT af demagnetization (= goethite concentration only). The correlative deltaic Arguis Fm. section coarsens up section from a condensed middle-outer neritic glauconite sandstone and marl sequence to proximal prodeltaic shales and siltstones, to

  3. Long-term interactions between man and the fluvial environment - case of the Diyala alluvial fan, Iraq

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