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Sample records for bodrog river floodplain

  1. Hydrological Signature From River-Floodplain Interactions

    NASA Astrophysics Data System (ADS)

    Paiva, R. C. D.; Fleischmann, A. S.; Collischonn, W.; Sorribas, M.; Pontes, P. R.

    2015-12-01

    Understanding river-floodplain hydraulic processes is fundamental to promote comprehension of related water paths, biogeochemicalcyclesand ecosystems. Large river basins around the globe present enormous developed floodplains, which strongly affect flood waves and water dynamics. Since most of these river-floodplain interactions are not monitored, it is interesting to develop strategies to understand such processes through characteristic hydrological signatures, e.g. hydrographs. We studied observed hydrographs from large South American rivers and found that in several cases rivers with extensive wetlands present a particular hydrograph shape, with slower rising limb in relation to the receding one, due to storage effects and the associated decrease of wave celerity with stage. A negative asymmetry in the hydrograph is generated, which is higher when more water flows through floodplains upstream of the observed point. Finally, we studied the Amazon basin using gauged information and simulation results from the MGB-IPH regional hydrological model. Major rivers with larger wetland areas (e.g. Purus, Madeira and Juruá) were identified with higher negative asymmetry in their hydrographs. The hydrodynamic model was run in scenarios with and without floodplains, and results supported that floodplain storage affects hydrographs in creating a negative asymmetry, besides attenuating peaks, increasing hydrograph smoothness and increasing minimum flows. Finally, different wetland types could be distinguished with hydrograph shape, e.g. differing wetlands fed by local rainfall from wetlands due to overbank flow (floodplains). These metrics and concepts on hydrograph features have great potential to infer about river-floodplain processes from large rivers and wetland systems.

  2. High methane emission from Siberian river floodplains

    NASA Astrophysics Data System (ADS)

    Mi, Yanjiao; van Huissteden, Ko; Dolman, Han

    2013-04-01

    Methane contributes significantly to global warming. Methane emission is essentially the net result of a balance between CH4 production by methanogenic bacteria in anaerobic soil zones, and CH4 oxidation by methanotrophic bacteria in aerated soil zones and plants. Arctic and sub-arctic permafrost holds a large amount of climate vulnerable carbon. In particular river floodplains are carbon-rich soils. River floodplains in this area are periodically or permanently submerged. The occurrence of flooding decreases soil oxygen availability, providing an ideal anaerobic environment for methane generation. Here we compare the chamber measurements of the methane flux from tundra and floodplain of the Kytalyk site in Northeast Siberia. Model experiments on this site have also been carried out in order to better explain spatial and temporal variations in methane emissions from northern permafrost. This serves as a basis for further model development including modeling of the flooding regime on the floodplain.

  3. Floodplain Organic Carbon Storage in the Central Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Lininger, K.; Wohl, E.

    2014-12-01

    Floodplain storage of organic carbon is an important aspect of the global carbon cycle that is not well understood or quantified. Although it is understood that rivers transport organic carbon to the ocean, little is known about the quantity of stored carbon in boreal floodplains and the influence of fluvial processes on this storage. We present results on total organic carbon (TOC) content within the floodplains of two rivers, the Dall River and Preacher Creek, in the central Yukon River Basin in the Yukon Flats National Wildlife Refuge of Alaska. The results indicate that organic carbon storage is influenced by fluvial disturbance and grain size. The Dall River, which contains a large amount of floodplain carbon, is meandering and incised, with well-developed floodplain soils, a greater percentage of relatively old floodplain surfaces and a slower floodplain turnover time, and finer grain sizes. Preacher Creek stores less TOC, transports coarser grain sizes, and has higher rates of avulsion and floodplain turnover time. Within the floodplain of a particular river, large spatial heterogeneity in TOC content also exists as a function of depositional environment and age and vegetation community of the site. In addition, saturated regions of the floodplains, such as abandoned channels and oxbow lakes, contain more TOC compared to drier floodplain environments. Frozen alluvial soils likely contain carbon that could be released into the environment with melting permafrost, and thus quantifying the organic carbon content in the active layer of floodplain soils could provide insight into the characteristics of the permafrost beneath. The hydrology in these regions is changing due to permafrost melt, and floodplain areas usually saturated could be dried out, causing breakdown and outgassing of carbon stored in previously saturated soils. Ongoing work will result in a first-order estimate of active-layer floodplain carbon storage for the central Yukon River Basin.

  4. Inventory and Comparison of Floodplain Embankment along Large Rivers

    NASA Astrophysics Data System (ADS)

    Hudson, Paul

    2016-04-01

    Flood control is a fundamental human response to flood risk, and floodplain embankment by dike (levee) construction is among the oldest forms of societal impacts to natural systems. Large lowland alluvial valleys are some of Earth's most distinctive environments and represent high levels of geodiversity and biodiversity. Embankment of large lowland alluvial river valleys alters fundamental processes related to floodplain hydrology, sedimentation, and ecology and eventually results in a transformation of the embanked floodplain environment. Since embankment, many large lowland floodplains have been heaviliy modified for floodplain agriculture and include high population densities, increasing flood risk. While there is much discussion about the pros and cons of dike construction and the impact to floodplain environments there is no systematic inventory which documents the magnitude and intensity of floodplain embankment to lowland rivers. In this study we characterize and inventory floodplain embankment along large lowland alluvial valleys. The review includes some of Earth's largest embanked fluvial systems, and primarilly focuses on northern hemisphere rivers in the United States, Europe and Asia. Data sources includes the U.S. National Levee Database, SRTM DEM, recently obtained high resolution satellite imagery, various national topographic map series, and hydrologic data from the published literature. These data are integrated into a GIS framework to facilitate the measurement and characterisation of floodplain embankment. Spatial indices of floodplain embankment are constructed, including the intensity of embankment and how it relates to the natural floodplain and constriction of flooding.

  5. River mobility in a permafrost dominated floodplain

    NASA Astrophysics Data System (ADS)

    Rowland, J.; Wilson, C.; Brumby, S.; Pope, P.

    2009-04-01

    Along arctic coastlines, recent studies have attributed dramatic increases in the rates of shoreline erosion to global climate change and permafrost degradation. While across much of the arctic, changes in the size and number of lakes have been interpreted as the result of permafrost degradation altering surface water dynamics. The potential influence of climate change and permafrost thawing on the mobility and form of arctic rivers, however, has been relatively unexplored to date. In rivers located within permafrost, some to potentially most, of the cohesive bank strength may be derived from frozen materials. It is likely that, as permafrost thaws, river bank erosion may increase, in turn influencing both migration rates and channel planform. Using automated feature extraction software (GeniePro), we quantified the of the mobility of a 200 km reach of the Yukon River through the Yukon Flats region located just north of Fairbanks, Alaska, USA. The Yukon Flats is an area of comprised of both continuous and discontinuous permafrost. Based on both changes in lake distributions and wintertime river base flows, it has been suggested that permafrost in this area has been experiencing recent thawing. In this reach, the Yukon River transitions from a 2 km wide braided channel to a multi-thread meandering channel where individual threads are approximately 1 km wide and the floodplain preserves prior meander cutoffs and oxbow lakes. Preliminary results from thirty years of LANDSAT imagery shows a surprising stability of channel location (at the image resolution of 30m/pixel) given the channel form. Within the braid-belt there is localized relocation of channel threads and mid-channel islands, though along much of the reach, the change in the location of channels banks is close to the resolution of the imagery. At the most active bends, bank migration rates range from 0.007 to 0.02 channel widths per year. These rates are comparable to system wide average rates observed on

  6. How does floodplain width affect floodplain river ecology? A preliminary exploration using simulations

    NASA Astrophysics Data System (ADS)

    Power, Mary E.; Parker, Gary; Dietrich, William E.; Sun, Adrian

    1995-09-01

    Hydraulic food chain models allow us to explore the linkages of river discharge regimes and river-floodplain morphology to the structure and dynamics of modeled food webs. Physical conditions (e.g. depth, width, velocity) that vary with river discharge affect the performance (birth, growth, feeding, movement, or death rates) of organisms or trophic groups. Their performances in turn affect their impacts on food webs and ecosystems in channel and floodplain habitats. Here we explore the impact of floodplain width (modeled as 1 ×, 10× and 40× the channel width) on a food web with two energy sources (detritus and vegetation), invertebrates that consume these, a size structured fish population which consumes invertebrates and in which larger fish cannibalize small fish, and birds which feed on large fish. Hydraulic linkages to trophic dynamics are assumed to be mediated in three ways: birds feed efficiently only in shallow water; plant carrying capacity varies non-linearly with water velocity, and mobile and drifting organisms are diluted and concentrated with spillover of river discharge to the floodplain, and its reconfinement to the channel. Aspects of this model are based on field observations of Junk and Bailey from the Amazon, of Sparks from the Mississippi, and on our observations of the Fly River in Papua New Guinea. The model produced several counter-intuitive results. Biomass of invertebrates and fish increased with floodplain width, but much more rapidly from 1 × to 10 × floodplains than from 10 × to 40 × floodplains. For birds, maximum biomass occurred on the 10× floodplain. Initially high bird biomass on the 40 × floodplain declined to extinction over time, because although favorable fishing conditions (shallow water) were most prolonged on the widest floodplain, this advantage was more than offset by the greater dilution of prey after spillover. Bird predation on large fish sometimes increased their biomass, by reducing cannibalism and thereby

  7. Reoccupation of floodplains by rivers and its relation to the age structure of floodplain vegetation

    USGS Publications Warehouse

    Konrad, Christopher P.

    2012-01-01

    River channel dynamics over many decades provide a physical control on the age structure of floodplain vegetation as a river occupies and abandons locations. Floodplain reoccupation by a river, in particular, determines the interval of time during which vegetation can establish and mature. A general framework for analyzing floodplain reoccupation and a time series model are developed and applied to five alluvial rivers in the United States. Channel dynamics in these rivers demonstrate time-scale dependence with short-term oscillation in active channel area in response to floods and subsequent vegetation growth and progressive lateral movement that accounts for much of the cumulative area occupied by the rivers over decades. Rivers preferentially reoccupy locations recently abandoned causing a decreasing probability of reoccupation with time since abandonment. For a typical case, a river is 10 times more likely to reoccupy an area it abandoned in the past decade than it is to reoccupy an area it abandoned 30 yrs ago. The decreasing probability of reoccupation over time is consistent with observations of persistent stands of late seral stage floodplain forest. A power function provides a robust approach for estimating the cumulative area occupied by a river and the age structure of riparian forests resulting from a specific historical sequence of streamflow in comparison to either linear or exponential alternatives.

  8. Abandoned floodplain plant communities along a regulated dryland river

    USGS Publications Warehouse

    Reynolds, L. V.; Shafroth, Patrick B.; House, P. K.

    2014-01-01

    Rivers and their floodplains worldwide have changed dramatically over the last century because of regulation by dams, flow diversions and channel stabilization. Floodplains no longer inundated by river flows following dam-induced flood reduction comprise large areas of bottomland habitat, but the effects of abandonment on plant communities are not well understood. Using a hydraulic flow model, geomorphic mapping and field surveys, we addressed the following questions along the Bill Williams River, Arizona: (i) What per cent of the bottomland do abandoned floodplains comprise? and (ii) Are abandoned floodplains quantitatively different from adjacent xeric and riparian surfaces in terms of vegetation composition and surface sediment? We found that nearly 70% of active channel and floodplain area was abandoned following dam installation. Abandoned floodplains along the Bill Williams River tend to be similar to each other yet distinct from neighbouring habitats: they have been altered physically from their historic state, leading to distinct combinations of surface sediments, hydrology and plant communities. Abandoned floodplains may transition to xeric communities over time but are likely to retain some riparian qualities as long as there is access to relatively shallow ground water. With expected increases in water demand and drying climatic conditions in many regions, these surfaces and associated vegetation will continue to be extensive in riparian landscapes worldwide

  9. Fluvial Landforms and Landscape Transformations on a Large River Floodplain: Willamette River, Oregon, USA

    NASA Astrophysics Data System (ADS)

    Wallick, R.

    2015-12-01

    Recent detailed mapping of the Willamette River floodplain in northwestern Oregon reveals insights into the floodplain landforms, their formative processes, and historical landscape transformations. Hierarchical mapping classification based mainly upon lidar topography, supplemented by aerial photographs, historical channel and soil maps, and targeted coring of floodplain soils, was carried out for 200 km of the mainstem Willamette River floodplain above Willamette Falls where floodplain landforms mainly reflect fluvial and anthropogenic influences. Stark differences in the character and distribution of floodplain landforms and their underlying stratigraphy give rise to three distinct process regimes along the fluvial portion of the Willamette River. Floodplain surfaces along 60 km of the Upper Willamette River floodplain generally rise 1-2 m above the low-flow water surface and are bisected by complex assemblage of overflow channels and large-amplitude abandoned bends formed by avulsions along this historically multi-thread anastomosing reach. Downstream, the 90 km-long Middle Willamette River between Corvallis and Newburg Pool becomes increasingly entrenched within its floodplain, with floodplains gradually rising up to 8 m above the low flow water surface. These floodplain surfaces are dominated by ridge and swale topography with occasional floodbasins reflecting gradual meander migration and floodplain aggradation. The 50 km-long Newberg Pool is entrenched and confined by Pleistocene Missoula flood deposits and bedrock valley walls. This low-gradient reach extends to the lip of the15-m high Willamette Falls. Historical declines in flood magnitude, bed-material supply, large wood, and bank erodibility result in a more stable modern-day floodplain with narrower active-channel corridor flanked by relict landforms formed by historical flow and sediment regime. Landscape transformations vary across the three process regimes but are greatest along Upper Willamette

  10. Ecology of invasive Melilotus alba on Alaskan glacial river floodplains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    White sweetclover has recently invaded glacial river floodplains in Alaska. We sampled vegetation and measured environmental variables along transects located along the Nenana, Matanuska, and Stikine Rivers to describe plant communities and to determine the effects of white sweetclover on other plan...

  11. A New Hydrogeological Research Site in the Willamette River Floodplain

    EPA Science Inventory

    The Willamette River is a ninth-order tributary of the Columbia which passes through a productive and populous region in northwest Oregon. Where unconstrained by shoreline revetments, the floodplain of this river is a high-energy, dynamic system which supports a variety of ripari...

  12. Aquatic habitats in relation to river flow in the Apalachicola River floodplain, Florida

    USGS Publications Warehouse

    Light, Helen M.; Darst, Melanie R.; Grubbs, J.W.

    1998-01-01

    This study is part of a larger effort to identify fresh water needs throughout the region and develop a mechanism for basinwide water management. Quantitative estimates of the amount of aquatic habitat in the floodplain in relation to river flow are presented. Plates show streams, lakes, and floodplain forests connected to the main river channel at selected flows; an analysis of long-term flow record in the Apalachicola River; and a review of the literature regarding fishes in floodplains of the Apalachicola River and other rivers of the Eastern United States. Examples show how this report can be used to assess impacts of flow alterations on aquatic habitats and fishes.

  13. Floodplain lakes and alluviation cycles of the lower Colorado River

    NASA Astrophysics Data System (ADS)

    Malmon, D.; Felger, T. J.; Howard, K. A.

    2007-05-01

    The broad valleys along the lower Colorado River contain numerous bodies of still water that provide critical habitat for bird, fish, and other species. This chain of floodplain lakes is an important part of the Pacific Flyway - the major north-south route of travel for migratory birds in the western Hemisphere - and is also used by many resident bird species. In addition, isolated floodplain lakes may provide the only viable habitat for endangered native fish such as the razorback sucker, vulnerable to predation by introduced species in the main stem of the Colorado River. Floodplain lakes typically occupy former channel courses of the river and formed as a result of river meandering or avulsion. Persistent fluvial sediment deposition (aggradation) creates conditions that favor rapid formation and destruction of floodplain lakes, while long term river downcutting (degradation) inhibits their formation and evolution. New radiocarbon dates from wood recovered from drill cores near Topock, AZ indicate that the river aggraded an average of 3 mm/yr in the middle and late Holocene. Aggradational conditions before Hoover Dam was built were associated with rapid channel shifting and frequent lake formation. Lakes had short life spans due to rapid infilling with fine-grained sediment during turbid floods on the unregulated Colorado River. The building of dams and of armored banks had a major impact on floodplain lakes, not only by drowning large portions of the valley beneath reservoirs, but by preventing new lake formation in some areas and accelerating it in others. GIS analyses of three sets of historical maps show that both the number and total area of isolated (i.e., not linked to the main channel by a surface water connection) lakes in the lower Colorado River valley increased between 1902 and the 1950s, and then decreased though the 1970s. River bed degradation below dams inhibits channel shifting and floodplain lake formation, and the capture of fines behind the

  14. Hyporheic flow patterns in relation to large river floodplain attributes

    EPA Science Inventory

    Field-calibrated models of hyporheic flow have emphasized low-order headwater systems. In many cases, however, hyporheic flow in large lowland river floodplains may be an important contributor to ecosystem services such as maintenance of water quality and habitat. In this study, ...

  15. Predicting the fate of sediment and pollutants in river floodplains.

    PubMed

    Malmon, Daniel V; Dunne, Thomas; Reneau, Steven L

    2002-05-01

    Geological processes such as erosion and sedimentation redistribute toxic pollutants introduced to the landscape by mining, agriculture, weapons development, and other human activities. A significant portion of these contaminants is insoluble, adsorbing to soils and sediments after being released. Geologists have long understood that much of this sediment is stored in river floodplains, which are increasingly recognized as important nonpoint sources of pollution in rivers. However, the fate of contaminated sediment has generally been analyzed using hydrodynamic models of in-channel processes, ignoring particle exchange with the floodplain. Here, we present a stochastic theory of sediment redistribution in alluvial valley floors that tracks particle-bound pollutants and explicitly considers sediment storage within floodplains. We use the theory to model the future redistribution and radioactive decay of 137Cs currently stored on sediment in floodplains at the Los Alamos National Laboratory (LANL) in New Mexico. Model results indicate that floodplain storage significantly reduces the rate of sediment delivery from upper Los Alamos Canyon, allowing 50% of the 137Cs currently residing in the valley floor to decay radioactively before leaving LANL. A sensitivity analysis shows that the rate of sediment overturn in the valley (and hence, the total amount of radioactive 137Cs predicted to leave LANL) is significantly controlled by the rate of sediment exchange with the floodplain. Our results emphasize that flood plain sedimentation and erosion processes can strongly influence the redistribution of anthropogenic pollutants in fluvial environments. We introduce a new theoretical framework for examining this interaction, which can provide a scientific basis for decision-making in a wide range of river basin management scenarios.

  16. 77 FR 56189 - Proposed Information Collection; Comment Request; Elwha River Dam Removal and Floodplain...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-12

    ... River Dam Removal and Floodplain Restoration Ecosystem Service Valuation Pilot Project AGENCY: National... Elwha River Dam Removal and Floodplain Restoration Ecosystem Service Valuation Survey it has developed... U.S. history. This project, along with restoration actions planned for the floodplain and...

  17. Low Elevation Old Channel Features of the Willamette River Floodplain Support High Subsurface Denitrification Rates

    EPA Science Inventory

    Background/Question/Methods: Large river floodplains are poor nitrate pollution buffers when polluted groundwater moves beneath biogeochemically retentive zones prior to entering the main channel. However, in floodplain regions with extensive backwaters and organic carbon acc...

  18. Wetland tree transpiration modified by river-floodplain connectivity

    USGS Publications Warehouse

    Allen, Scott T; Krauss, Ken W.; Cochran, J. Wesley; King, Sammy L.; Keim, Richard F.

    2016-01-01

    Hydrologic connectivity provisions water and nutrient subsidies to floodplain wetlands and may be particularly important in floodplains with seasonal water deficits through its effects on soil moisture. In this study, we measured sapflow in 26 trees of two dominant floodplain forest species (Celtis laevigata and Quercus lyrata) at two hydrologically distinct sites in the lower White River floodplain in Arkansas, USA. Our objective was to investigate how connectivity-driven water table variations affected water use, an indicator of tree function. Meteorological variables (photosynthetically active radiation and vapor pressure deficit) were the dominant controls over water use at both sites; however, water table variations explained some site differences. At the wetter site, highest sapflow rates were during a late-season overbank flooding event, and no flood stress was apparent. At the drier site, sapflow decreased as the water table receded. The late-season flood pulse that resulted in flooding at the wetter site did not affect the water table at the drier site; accordingly, higher water use was not observed at the drier site. The species generally associated with wetter conditions (Q. lyrata) was more positively responsive to the flood pulse. Flood water subsidy lengthened the effective growing season, demonstrating ecological implications of hydrologic connectivity for alleviating water deficits that otherwise reduce function in this humid floodplain wetland.

  19. Wetland tree transpiration modified by river-floodplain connectivity

    NASA Astrophysics Data System (ADS)

    Allen, Scott T.; Krauss, Ken W.; Cochran, J. Wesley; King, Sammy L.; Keim, Richard F.

    2016-03-01

    Hydrologic connectivity provisions water and nutrient subsidies to floodplain wetlands and may be particularly important in floodplains with seasonal water deficits through its effects on soil moisture. In this study, we measured sapflow in 26 trees of two dominant floodplain forest species (Celtis laevigata and Quercus lyrata) at two hydrologically distinct sites in the lower White River floodplain in Arkansas, USA. Our objective was to investigate how connectivity-driven water table variations affected water use, an indicator of tree function. Meteorological variables (photosynthetically active radiation and vapor pressure deficit) were the dominant controls over water use at both sites; however, water table variations explained some site differences. At the wetter site, highest sapflow rates were during a late-season overbank flooding event, and no flood stress was apparent. At the drier site, sapflow decreased as the water table receded. The late-season flood pulse that resulted in flooding at the wetter site did not affect the water table at the drier site; accordingly, higher water use was not observed at the drier site. The species generally associated with wetter conditions (Q. lyrata) was more positively responsive to the flood pulse. Flood water subsidy lengthened the effective growing season, demonstrating ecological implications of hydrologic connectivity for alleviating water deficits that otherwise reduce function in this humid floodplain wetland.

  20. Ecology of invasive Melilotus albus on Alaskan glacial river floodplains

    USGS Publications Warehouse

    Conn, Jeff S.; Werdin-Pfisterer, Nancy R.; Beattie, Katherine L.; Densmore, Roseann V.

    2011-01-01

    Melilotus albus (white sweetclover) has invaded Alaskan glacial river floodplains. We measured cover and density of plant species and environmental variables along transects perpendicular to the Nenana, Matanuska, and Stikine Rivers to study interactions between M. albus and other plant species and to characterize the environment where it establishes. Melilotus albus was a pioneer species on recently disturbed sites and did not persist into closed canopy forests. The relationships between M. albus cover and density and other species were site-specific.Melilotus albus was negatively correlated with native species Elaeagnus commutata at the Nenana River, but not at the Matanuska River. Melilotus albus was positively correlated with the exotic species Crepis tectorumand Taraxacum officinale at the Matanuska River and T. officinale on the upper Stikine River. However, the high density of M. albus at a lower Stikine River site was negatively correlated with T. officinale and several native species including Lathyrus japonicus var. maritimus and Salix alaxensis. Glacial river floodplains in Alaska are highly disturbed and are corridors for exotic plant species movement. Melilotus albus at moderate to low densities may facilitate establishment of exotic species, but at high densities can reduce the cover and density of both exotic and native species.

  1. Habitat modeling in a southeastern aluvial floodplain river

    SciTech Connect

    Leonard, P.; Bell, C.; Boltz, J.

    1995-12-31

    The physical habitat modeling approach of the Instream Flow Incremental Methodology (IFIM) is frequently used to conduct impact assessments and determine instream flow needs downstream of hydroelectric facilities. In the process of relicensing the Sinclair Hydroelectric Project, Georgia Power Company conducted an IFIM study on a seventy-mile section of the Oconee River from Sinclair Dam downstream to Dublin, Georgia. The Oconee River in the study area is a low-gradient, meandering alluvial river with an extensive bottomland hardwood floodplain. Knowledge of such southeastern floodplain rivers suggests that in addition to the traditional IFIM concepts of instream habitat, inclusion of other important habitat components such as woody debris substrates, access to seasonally inundated floodplain habitat, and recruitment from oxbow lakes are potentially important determinants of fish species composition and productivity which should be considered in instream flow studies. This paper describes: (1) several new habitat modeling approaches that were used to address these important habitat components within the context of IFIM; and, (2) how they were used as the basis for evaluating changes in habitat resulting from various alternative operations of the Sinclair Project.

  2. Influence of dams on river-floodplain dynamics in the Elwha River, Washington

    USGS Publications Warehouse

    Kloehn, K.K.; Beechie, T.J.; Morley, S.A.; Coe, H.J.; Duda, J.J.

    2008-01-01

    The Elwha dam removal project presents an ideal opportunity to study how historic reduction and subsequent restoration of sediment supply alter river-floodplain dynamics in a large, forested river floodplain. We used remote sensing and onsite data collection to establish a historical record of floodplain dynamics and a baseline of current conditions. Analysis was based on four river reaches, three from the Elwha River and the fourth from the East Fork of the Quinault River. We found that the percentage of floodplain surfaces between 25 and 75 years old decreased and the percentage of surfaces >75 years increased in reaches below the Elwha dams. We also found that particle size decreased as downstream distance from dams increased. This trend was evident in both mainstem and side channels. Previous studies have found that removal of the two Elwha dams will initially release fine sediment stored in the reservoirs, then in subsequent decades gravel bed load supply will increase and gradually return to natural levels, aggrading river beds up to 1 m in some areas. We predict the release of fine sediments will initially create bi-modal grain size distributions in reaches downstream of the dams, and eventual recovery of natural sediment supply will significantly increase lateral channel migration and erosion of floodplain surfaces, gradually shifting floodplain age distributions towards younger age classes.

  3. Hydromorphological control of nutrient cycling in complex river floodplain systems

    NASA Astrophysics Data System (ADS)

    Hein, T.; Bondar-Kunze, E.; Felkl, M.; Habersack, H.; Mair, M.; Pinay, G.; Tritthart, M.; Welti, N.

    2009-04-01

    Riparian zones and floodplains are key components within river ecosystems controlling nutrient cycling by promoting transformation processes and thus, act as biogeochemical hot spots. The intensity of these processes depends on the exchange conditions (the connectivity) with the main channel and the morphological setting of the water bodies. At the landscape scale, three interrelated principles of hydromorphological dynamics can be formulated regarding the cycling and transfer of carbon and nutrients in large rivers ecosystems: a) The mode of carbon and nutrient delivery affects ecosystem functioning; b) Increasing residence time and contact area impact nutrient transformation; c) Floods and droughts are natural events that strongly influence pathways of carbon and nutrient cycling. These three principles of hydromorphological dynamics control the nutrient uptake and retention and are linked over different temporal and spatial scales. All three factors can be strongly affected by natural disturbances or anthropogenic impacts, through a change in either the water regime or the geomorphologic setting of the river valley. Any change in natural water regimes will affect the biogeochemistry of riparian zones and floodplains as well as their ability to cycle and mitigate nutrient fluxes originating from upstream and/or upslope. Especially these areas have been altered by river regulation and land use changes over the last 200 years leading to the deterioration of the functioning of these compartments within the riverine landscape. The resulting deficits have prompted rehabilitation and restoration measures aiming to increase the spatial heterogeneity, the complexity, of these ecosystems. Yet, a more integrated approach is needed considering the present status of nutrient dynamics and the effects of restoration measures at different scales. The present paper analyses the effects of river side-arm restoration on ecosystem functions within the side-arm and highlights

  4. Spatial variability in hydrologic connectivity between a coastal river and its floodplain

    NASA Astrophysics Data System (ADS)

    Castillo, C. R.; Guneralp, I.; Hales, B. U.

    2015-12-01

    Significant in the transport and dispersal of energy, matter, and biota within riverine environments, hydrologic connectivity has become fundamental in understanding river-floodplain process and concepts associated with environmental flows. Hydrologic connectivity between a river and its floodplain is dependent on floodplain geomorphology, channel hydraulics, land cover, and groundwater dynamics. In this study, we examine the floodplain morphology of the Mission River on the Coastal Bend of Texas. Utilizing a LiDAR-derived digital elevation model, we develop a relative digital elevation model (RDEM), with respect to river-stage, for a reach of the river-floodplain system. To assess the dominant flow directions, and thus, characterize the connectivity within the floodplain, we determine hydrological facets—landscape patches with their own respective outlet and high internal surface water connectivity. Guided by historical streamflow records, we systematically threshold the RDEM to determine the spatial characteristics of floodplain inundation under various river-stages. The increasing aerial extent of floodplain inundation from increases in river-stage results in distinct patterns of river channel-floodplain connectivity. We analyze the spatial arrangement of facets with regard to inundation in order to quantify floodplain connectivity and complexity at various river-stages using graph theory and landscape metrics. Our results indicate that floodplain connectivity and complexity change nonlinearly with increases in river-stage; with the greatest increases in connectivity and complexity occurring well below bankfull discharge. Floodplains provide valuable ecosystem services and this study helps improve our understanding of process-form relationships in river-floodplain systems' that informs environmental policy for effective management of these services.

  5. Acidification of floodplains due to river level decline during drought.

    PubMed

    Mosley, Luke M; Palmer, David; Leyden, Emily; Cook, Freeman; Zammit, Benjamin; Shand, Paul; Baker, Andrew; W Fitzpatrick, Rob

    2014-06-01

    A severe drought from 2007 to 2010 resulted in the lowest river levels (1.75 m decline from average) in over 90 years of records at the end of the Murray-Darling Basin in South Australia. Due to the low river level and inability to apply irrigation, the groundwater depth on the adjacent agricultural flood plain also declined substantially (1-1.5 m) and the alluvial clay subsoils dried and cracked. Sulfidic material (pH>4, predominantly in the form of pyrite, FeS2) in these subsoils oxidised to form sulfuric material (pH<4) over an estimated 3300 ha on 13 floodplains. Much of the acidity in the deeply cracked contaminated soil layers was in available form (in pore water and on cation exchange sites), with some layers having retained acidity (iron oxyhydroxysulfate mineral jarosite). Post drought, the rapid raising of surface and ground water levels mobilised acidity in acid sulfate soil profiles to the floodplain drainage channels and this was transported back to the river via pumping. The drainage water exhibited low pH (2-5) with high soluble metal (Al, Co, Mn, Fe, Mn, Ni, and Zn) concentrations, in exceedance of guidelines for ecosystem protection. Irrigation increased the short-term transport of acidity, however loads were generally greater in the non-irrigation (winter) season when rainfall is highest (0.0026 tonnes acidity/ha/day) than in the irrigation (spring-summer) season (0.0013 tonnes acidity/ha/day). Measured reductions in groundwater acidity and increases in pH have been observed over time but severe acidification persisted in floodplain sediments and waters for over two years post-drought. Results from 2-dimensional modelling of the river-floodplain hydrological processes were consistent with field measurements during the drying phase and illustrated how the declining river levels led to floodplain acidification. A modelled management scenario demonstrated how river level stabilisation and limited irrigation could have prevented, or greatly lessened

  6. Acidification of floodplains due to river level decline during drought.

    PubMed

    Mosley, Luke M; Palmer, David; Leyden, Emily; Cook, Freeman; Zammit, Benjamin; Shand, Paul; Baker, Andrew; W Fitzpatrick, Rob

    2014-06-01

    A severe drought from 2007 to 2010 resulted in the lowest river levels (1.75 m decline from average) in over 90 years of records at the end of the Murray-Darling Basin in South Australia. Due to the low river level and inability to apply irrigation, the groundwater depth on the adjacent agricultural flood plain also declined substantially (1-1.5 m) and the alluvial clay subsoils dried and cracked. Sulfidic material (pH>4, predominantly in the form of pyrite, FeS2) in these subsoils oxidised to form sulfuric material (pH<4) over an estimated 3300 ha on 13 floodplains. Much of the acidity in the deeply cracked contaminated soil layers was in available form (in pore water and on cation exchange sites), with some layers having retained acidity (iron oxyhydroxysulfate mineral jarosite). Post drought, the rapid raising of surface and ground water levels mobilised acidity in acid sulfate soil profiles to the floodplain drainage channels and this was transported back to the river via pumping. The drainage water exhibited low pH (2-5) with high soluble metal (Al, Co, Mn, Fe, Mn, Ni, and Zn) concentrations, in exceedance of guidelines for ecosystem protection. Irrigation increased the short-term transport of acidity, however loads were generally greater in the non-irrigation (winter) season when rainfall is highest (0.0026 tonnes acidity/ha/day) than in the irrigation (spring-summer) season (0.0013 tonnes acidity/ha/day). Measured reductions in groundwater acidity and increases in pH have been observed over time but severe acidification persisted in floodplain sediments and waters for over two years post-drought. Results from 2-dimensional modelling of the river-floodplain hydrological processes were consistent with field measurements during the drying phase and illustrated how the declining river levels led to floodplain acidification. A modelled management scenario demonstrated how river level stabilisation and limited irrigation could have prevented, or greatly lessened

  7. Acidification of floodplains due to river level decline during drought

    NASA Astrophysics Data System (ADS)

    Mosley, Luke M.; Palmer, David; Leyden, Emily; Cook, Freeman; Zammit, Benjamin; Shand, Paul; Baker, Andrew; W. Fitzpatrick, Rob

    2014-06-01

    A severe drought from 2007 to 2010 resulted in the lowest river levels (1.75 m decline from average) in over 90 years of records at the end of the Murray-Darling Basin in South Australia. Due to the low river level and inability to apply irrigation, the groundwater depth on the adjacent agricultural flood plain also declined substantially (1-1.5 m) and the alluvial clay subsoils dried and cracked. Sulfidic material (pH > 4, predominantly in the form of pyrite, FeS2) in these subsoils oxidised to form sulfuric material (pH < 4) over an estimated 3300 ha on 13 floodplains. Much of the acidity in the deeply cracked contaminated soil layers was in available form (in pore water and on cation exchange sites), with some layers having retained acidity (iron oxyhydroxysulfate mineral jarosite). Post drought, the rapid raising of surface and ground water levels mobilised acidity in acid sulfate soil profiles to the floodplain drainage channels and this was transported back to the river via pumping. The drainage water exhibited low pH (2-5) with high soluble metal (Al, Co, Mn, Fe, Mn, Ni, and Zn) concentrations, in exceedance of guidelines for ecosystem protection. Irrigation increased the short-term transport of acidity, however loads were generally greater in the non-irrigation (winter) season when rainfall is highest (0.0026 tonnes acidity/ha/day) than in the irrigation (spring-summer) season (0.0013 tonnes acidity/ha/day). Measured reductions in groundwater acidity and increases in pH have been observed over time but severe acidification persisted in floodplain sediments and waters for over two years post-drought. Results from 2-dimensional modelling of the river-floodplain hydrological processes were consistent with field measurements during the drying phase and illustrated how the declining river levels led to floodplain acidification. A modelled management scenario demonstrated how river level stabilisation and limited irrigation could have prevented, or greatly

  8. Net local removal of floodplain sediment by river meander migration

    NASA Astrophysics Data System (ADS)

    Lauer, J. Wesley; Parker, Gary

    2008-04-01

    Erosion from the banks of meandering rivers causes a local influx of sediment to the river channel. Most of the eroded volume is usually replaced in nearby point bars. However, the typical geometry of river bends precludes the local replacement of all eroded material because (i) point bars tend to be built to a lower elevation than cutbanks and (ii) point bars tend to be shorter than the eroding portion of cutbanks because of channel curvature. In a floodplain that is in equilibrium (i.e., neither increasing nor decreasing in volume), sediment eroded from cut banks must be replaced elsewhere on the floodplain. The local imbalance caused by differences in bank height should be balanced primarily by overbank deposition, while the local imbalance caused by curvature should be balanced primarily by deposition in abandoned stream courses or oxbow lakes. Estimates of these local imbalances based on remotely sensed measurements of bank geometry and channel migration have been made on four systems in the United States: a 91-km reach of the Pearl River in Louisiana and Mississippi, a 62-km reach of the Bogue Chitto River in Louisiana, a 35-km reach of the Neuse River in North Carolina, and a 2.7-km reach of the Vermillion River in Minnesota. For these systems, the total local imbalance, integrated over many bends, ranged from 0.36 to 2.27 m 3/yr/m of valley length (0.15 to 1.32 m 3/yr/m of channel length), or 7 to 45% of gross cutbank erosion, with a typical value of about 17%. When compared with gauged suspended sediment data, the measurements provide estimates of the relative importance of floodplains for storing material transported by a river system. The data suggest that even if the studied systems are near long-term mass balance equilibrium (as opposed to undergoing net deposition or erosion), almost all of the sand and in some cases much of the silt and clay in transit through these systems is likely to have spent some time stored in an upstream floodplain.

  9. Avian assemblages in the lower Missouri river floodplain

    USGS Publications Warehouse

    Thogmartin, W.E.; Gallagher, M.; Young, N.; Rohweder, J.J.; Durbian, F.; Knutson, M.G.

    2009-01-01

    Floodplain habitat provides important migration and breeding habitat for birds in the midwestern United States. However, few studies have examined how the avian assemblage changes with different stages of floodplain forest succession in the midwestern United States. In spring and summer from 2002 to 2004, we conducted 839 point counts in wet prairie/forbs fields, 547 point counts in early successional forests, and 434 point counts in mature forests to describe the migrating and breeding bird assemblage in the lower Missouri River floodplain. We recorded 131, 121, and 141 species in the three respective habitats, a number higher than most locations in the midwestern United States and comprising > 15% of all avian species in North America. Avian species diversity generally increased from west to east along the river, differed among land cover classes, but overlapped between seasons (migration and breeding) and years. Wet prairies were particularly important for conservation as there were 20 species of high conservation concern observed, including Dickcissels (Spiza americana). Important species for monitoring biotic integrity included the Northern Harrier (Circus cyaneus) and Bobolink (Dolichonyx oryzivorus) in wet prairie, Bell's Vireo (Vireo bellii) in early successional forest, and Northern Parula (Parula americana) and Prothonotary Warbler (Protonotaria citrea) in mature forest. ?? 2009, The Society of Wetland Scientists.

  10. Channel metamorphosis, floodplain disturbance, and vegetation development: Ain River, France

    NASA Astrophysics Data System (ADS)

    Marston, Richard A.; Girel, Jacky; Pautou, Guy; Piegay, Herve; Bravard, Jean-Paul; Arneson, Chris

    1995-09-01

    The purpose of this paper is to describe and explain channel metamorphosis of the Ain River in east-central France and the effects of this metamorphosis on floodplain disturbance and vegetation development. The Ain River is a 195 km long stream originating in the Jura Mountains which flows into the Rhône River between Lyon, France, and Geneva, Switzerland. The lower 40 km of the Ain River, beyond the mountain front, are situated in a valley of outwash deposits where the floodplain is 0.2 to 1.2 km wide. A complex mosaic of floodplain landscape units has developed. Maps dating back to 1766 and six sets of aerial photographs dated between 1945 and 1991 were used to document changes in channel pattern. Aerial photos and field surveys were used to compile maps of landscape units based on dominant vegetation life-forms, species, and substrate. Six maps dated between 1945 and 1991 were digitized in ARC/INFO and an overlay was generated to determine the changes in landscape units as related to channel disturbance. Change from a braided to a single-thread meandering channel probably took place in the period 1930-1950. The process of river entrenchment has occurred throughout the Holocene but has accelerated in the present century due to shortening of the river course, construction of lateral embankments, and vegetation encroachment following reservoir construction and cessation of wood-cutting and grazing. The increase in horizontal channel stability coupled with channel entrenchment have decreased floodplain disturbance and lowered the water table by approximately one meter. Pioneer and disturbance-dependent landscape units have experienced a more terrestrial-like succession to an alluvial forest. Abandoned channels have also been replaced by alluvial forests. On poorly drained soils, shrub-swamp communities of willow and hydrophytic herbaceous plants have been replaced by mixed forests of ash, alder, black poplar, and oak. On well drained alluvial soils, ash and oak

  11. Floodplain Sedimentation in Vegetated Areas of the Elwha River Floodplain, 2012-2014

    NASA Astrophysics Data System (ADS)

    Lauer, J. W.; Polka, J.

    2014-12-01

    The removal of the Elwha and Glines Canyon Dams from the Elwha River, near Port Angeles, Washington, has released a large pulse of sediment into the middle and lower reaches of the Elwha River. This sediment has important geomorphic, hydraulic, and ecological implications. Our project focuses on the deposition of fine sediment on vegetated parts of the Elwha floodplain using field observations of sediment accumulation in combination with a simplified physics numerical model, CAESAR-Lisflood. The floodplain of the Elwha is densely vegetated and in places is characterized by large amounts of local topographic variation. This makes measuring centimeter-scale overbank sedimentation difficult using traditional approaches such as lidar and total-station based cross-section surveys. To address this problem and to provide ground truth for more traditional surveying methods, we set up over 50 short (10-20 m long) cross-sections between sets of flagged trees and surveyed, at 1-meter intervals, ground elevation with respect to a spike set in each section. Nails in the trees ensure that the horizontal position of our measurements do not shift by more than a few centimeters from year to year. This approach allows sediment accumulation to be measured repeatedly with a precision we estimate to be on the order of a few centimeters, allowing us to estimate annual rates of local sedimentation. At a given point on the floodplain, sedimentation should depend significantly on the frequency of inundation. We simulate this for the 2012-2014 period using a CAESAR-Lisflood 2-D numerical model calibrated using a set of continuously recording staff gages. CAESAR-Lisflood uses simplified-physics hydraulic routines to efficiently simulate flow depth and velocity and to drive size-specific sediment transport and morphodynamic change. This allows the model to simulate changes in flood inundation probability for the post- removal period. CAESAR-based hydraulic results are used to interpret our

  12. Fish mediate high food web connectivity in the lower reaches of a tropical floodplain river.

    PubMed

    Jardine, Timothy D; Pusey, Bradley J; Hamilton, Stephen K; Pettit, Neil E; Davies, Peter M; Douglas, Michael M; Sinnamon, Vivian; Halliday, Ian A; Bunn, Stuart E

    2012-03-01

    High levels of hydrological connectivity during seasonal flooding provide significant opportunities for movements of fish between rivers and their floodplains, estuaries and the sea, possibly mediating food web subsidies among habitats. To determine the degree of utilisation of food sources from different habitats in a tropical river with a short floodplain inundation duration (~2 months), stable isotope ratios in fishes and their available food were measured from three habitats (inundated floodplain, dry season freshwater, coastal marine) in the lower reaches of the Mitchell River, Queensland (Australia). Floodplain food sources constituted the majority of the diet of large-bodied fishes (barramundi Lates calcarifer, catfish Neoarius graeffei) captured on the floodplain in the wet season and for gonadal tissues of a common herbivorous fish (gizzard shad Nematalosa come), the latter suggesting that critical reproductive phases are fuelled by floodplain production. Floodplain food sources also subsidised barramundi from the recreational fishery in adjacent coastal and estuarine areas, and the broader fish community from a freshwater lagoon. These findings highlight the importance of the floodplain in supporting the production of large fishes in spite of the episodic nature and relatively short duration of inundation compared to large river floodplains of humid tropical regions. They also illustrate the high degree of food web connectivity mediated by mobile fish in this system in the absence of human modification, and point to the potential consequences of water resource development that may reduce or eliminate hydrological connectivity between the river and its floodplain.

  13. The role of floodplain restoration in mitigating flood risk, Lower Missouri River, USA

    USGS Publications Warehouse

    Jacobson, Robert B.; Lindner, Garth; Bitner, Chance

    2009-01-01

    Recent extreme floods on the Lower Missouri River have reinvigorated public policy debate about the potential role of floodplain restoration in decreasing costs of floods and possibly increasing other ecosystem service benefits. The first step to addressing the benefits of floodplain restoration is to understand the interactions of flow, floodplain morphology, and land cover that together determine the biophysical capacity of the floodplain. In this article we address interactions between ecological restoration of floodplains and flood-risk reduction at 3 scales. At the scale of the Lower Missouri River corridor (1300 km) floodplain elevation datasets and flow models provide first-order calculations of the potential for Missouri River floodplains to store floods of varying magnitude and duration. At this same scale assessment of floodplain sand deposition from the 2011 Missouri River flood indicates the magnitude of flood damage that could potentially be limited by floodplain restoration. At the segment scale (85 km), 1-dimensional hydraulic modeling predicts substantial stage reductions with increasing area of floodplain restoration; mean stage reductions range from 0.12 to 0.66 m. This analysis also indicates that channel widening may contribute substantially to stage reductions as part of a comprehensive strategy to restore floodplain and channel habitats. Unsteady 1-dimensional flow modeling of restoration scenarios at this scale indicates that attenuation of peak discharges of an observed hydrograph from May 2007, of similar magnitude to a 10 % annual exceedance probability flood, would be minimal, ranging from 0.04 % (with 16 % floodplain restoration) to 0.13 % (with 100 % restoration). At the reach scale (15–20 km) 2-dimensional hydraulic models of alternative levee setbacks and floodplain roughness indicate complex processes and patterns of flooding including substantial variation in stage reductions across floodplains depending on topographic complexity

  14. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes.

    PubMed

    Hauer, F Richard; Locke, Harvey; Dreitz, Victoria J; Hebblewhite, Mark; Lowe, Winsor H; Muhlfeld, Clint C; Nelson, Cara R; Proctor, Michael F; Rood, Stewart B

    2016-06-01

    Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologic-altering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth.

  15. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes

    PubMed Central

    Hauer, F. Richard; Locke, Harvey; Dreitz, Victoria J.; Hebblewhite, Mark; Lowe, Winsor H.; Muhlfeld, Clint C.; Nelson, Cara R.; Proctor, Michael F.; Rood, Stewart B.

    2016-01-01

    Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologic-altering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth. PMID:27386570

  16. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes

    USGS Publications Warehouse

    Hauer, F. Richard; Locke, Harvey; Dreitz, Victoria; Hebblewhite, Mark; Lowe, Winsor; Muhlfeld, Clint C.; Nelson, Cara; Proctor, Michael F; Rood, Stewart B.

    2016-01-01

    Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologicaltering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth.

  17. Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes.

    PubMed

    Hauer, F Richard; Locke, Harvey; Dreitz, Victoria J; Hebblewhite, Mark; Lowe, Winsor H; Muhlfeld, Clint C; Nelson, Cara R; Proctor, Michael F; Rood, Stewart B

    2016-06-01

    Gravel-bed river floodplains in mountain landscapes disproportionately concentrate diverse habitats, nutrient cycling, productivity of biota, and species interactions. Although stream ecologists know that river channel and floodplain habitats used by aquatic organisms are maintained by hydrologic regimes that mobilize gravel-bed sediments, terrestrial ecologists have largely been unaware of the importance of floodplain structures and processes to the life requirements of a wide variety of species. We provide insight into gravel-bed rivers as the ecological nexus of glaciated mountain landscapes. We show why gravel-bed river floodplains are the primary arena where interactions take place among aquatic, avian, and terrestrial species from microbes to grizzly bears and provide essential connectivity as corridors for movement for both aquatic and terrestrial species. Paradoxically, gravel-bed river floodplains are also disproportionately unprotected where human developments are concentrated. Structural modifications to floodplains such as roads, railways, and housing and hydrologic-altering hydroelectric or water storage dams have severe impacts to floodplain habitat diversity and productivity, restrict local and regional connectivity, and reduce the resilience of both aquatic and terrestrial species, including adaptation to climate change. To be effective, conservation efforts in glaciated mountain landscapes intended to benefit the widest variety of organisms need a paradigm shift that has gravel-bed rivers and their floodplains as the central focus and that prioritizes the maintenance or restoration of the intact structure and processes of these critically important systems throughout their length and breadth. PMID:27386570

  18. Floodplain Modulation of Solute Fluxes from Mountainous Regions: the Amazonian Madre de Dios River Case Study

    NASA Astrophysics Data System (ADS)

    Torres, M. A.; West, A. J.; Baronas, J. J.; Ponton, C.; Clark, K. E.; Feakins, S. J.; Galy, V.

    2015-12-01

    In many large river systems, solutes released by chemical weathering in mountainous regions are transported through floodplains before being discharged into the ocean. Chemical reactions within floodplains can both add and remove solutes, significantly modulating fluxes. Despite their importance in the relationship between tectonic uplift and solute fluxes to the ocean, many aspects of floodplain processes are poorly constrained since the chemistry of large rivers is also significantly affected by the mixing between multiple tributaries, which makes the separation and quantification of floodplain processes challenging. Here we explore how floodplain processes affect a suite of major and trace elements in the Madre de Dios River system in Peru. To separate floodplain processes from conservative mixing, we developed a tributary mixing model that uses water isotopic ratios and chloride concentrations measured in each tributary and upstream and downstream of each tributary confluence for all major tributaries along a floodplain reach. The results of the tributary mixing model allow for the chemical composition of the mainstem of the Madre de Dios River to be modeled assuming completely conservative mixing. Differences between the modeled and measured chemical composition of the mainstem are then used to identify and quantify the effects of floodplain processes on different solutes. Our results show that during both the wet and dry seasons, Li is removed and Ca, Mg, and Sr are added to the dissolved load during floodplain transit. Other solutes, like Na and SO4, appear to behave conservatively during floodplain transit. Likely, the removal of Li from the dissolved load reflects the precipitation of secondary silicate minerals in the floodplain. The release of Ca, Mg, and Sr likely reflects the dissolution of detrital carbonate minerals. Our analyses also show that tributaries with Andean headwaters contribute disproportionately to solute budgets while the water budget

  19. Channel pattern and river-floodplain dynamics in forested mountain river systems

    NASA Astrophysics Data System (ADS)

    Beechie, Timothy J.; Liermann, Martin; Pollock, Michael M.; Baker, Sarah; Davies, Jeremy

    2006-08-01

    Channel pattern effectively stratifies the dynamics of rivers and floodplains in forested mountain river systems of the Pacific Northwest, USA. Straight channels are least dynamic, with relatively slow floodplain turnover and floodplains dominated by old surfaces. Braided channels are most dynamic, with floodplain turnover as low as 25 years and predominantly young floodplain surfaces. Island-braided and meandering channels have intermediate dynamics, with moderately frequent disturbances (erosion of floodplain patches) maintaining a mix of old and young surfaces. Return intervals for the erosion of floodplains increase in the order of braided, island-braided, meandering, and straight (8, 33, 60, and 89 years, respectively). A threshold for the lateral migration of a channel occurs at a bankfull width of 15-20 m. The most likely mechanism underlying this threshold is that larger channels are deep enough to erode below the rooting zone of bank vegetation. Above this threshold, channels not confined between valley walls exhibit channel patterns distinguishable by slope and discharge, and slope-discharge domains can be used to predict channel patterns. Meandering and braided patterns are most consistently identified by the model, and prediction errors are largely associated with indistinct transitions among channel patterns that are adjacent in plots of slope against discharge. Locations of straight channels are difficult to identify accurately with the current model. The predicted spatial distribution of channel patterns reflects a downstream decline in channel slope, which is likely correlated with a declining ratio of bed load to suspended load. Ecological theory suggests that biological diversity should be highest where the intermediate disturbance regime of island-braided channels sustains high diversity of habitat and successional states through time.

  20. Sediment dynamics within the intertidal floodplain of the lower Amazon River

    NASA Astrophysics Data System (ADS)

    Fricke, A. T.; Nittrouer, C. A.; Ogston, A. S.; Nowacki, D. J.; Asp, N. E.; Souza Filho, P. W.

    2014-12-01

    Tidal influence extends ~800 kilometers upstream of the Amazon River mouth, producing semidiurnal oscillations in water elevation and slowing or reversing the flow of the world's largest river. This tidally influenced reach, known as the tidal river, is flanked by an expansive intertidal floodplain, and includes confluences with two large tributaries, the Xingu and Tapajós. The relative magnitude of the seasonal and tidal signals changes along the length of the tidal river, yielding diverse floodplain environments that span a range of seasonal and tidal influence. Near the upstream limit of tides, natural levees isolate the river from the floodplain during low to moderate flows, while in the lower tidal river, natural levees are absent and river-floodplain exchange is dominated by the tides rather than seasonal variation in river stage. This difference between fluvial and tidal systems strongly affects the nature of sediment exchange between the channel and floodplain, including frequency, duration, and depth of inundation. Here we present data on the impact of this fluvial-tidal continuum on sedimentary processes in the floodplain and resultant depositional signatures. Changes in levee prominence, grain size, and sediment accumulation combine to produce the distinct morphologies of floodplain lakes, intertidal backswamps, and intertidal flats. In addition to sediment accumulation on the periodically exposed floodplain, Amazon River sediment accumulates within the drowned tributary confluences of the Xingu and Tapajós Rivers. Here seasonal and tidal changes in water temperature, discharge, and suspended-sediment concentration drive barotropic and baroclinic flows that transport Amazon River sediment into tributary basins. These findings help to constrain the fate of sediment within the ungauged Amazon tidal river, and will help in understanding the response of the lower Amazon River to changes in accommodation space associated with rising sea level, and changes

  1. Properties of a 5500-year-old flood-plain in the Loup River Basin, Nebraska

    NASA Astrophysics Data System (ADS)

    May, David W.

    2003-12-01

    Flood-plain aggradation within the Loup River Basin of central Nebraska was episodic and alternated with incision throughout much of the Holocene. A widespread episode of flood-plain stability, however, occurred about 5700-5100 cal. year BP. The purpose of this paper is to describe the properties of this buried flood-plain at six sites in the basin, to consider why the properties of the buried flood-plain vary from site to site, and to evaluate possible reasons why the Loup River flood-plains stabilized 5500 years ago. Episodic valley-bottom aggradation was common during flood-plain formation at five of the six sites. The radiocarbon ages, particle-size data, and organic-carbon data for the buried flood-plain reveal that valley-bottom aggradation generally slowed between about 5700 and 5100 cal. year BP. Erratic down-profile changes in percentages of sand, clay, and organic matter indicate flood-plain sedimentation and soil formation were often episodic. Sand and clay rarely show a steady fining-upward trend. Organic matter fluctuates with depth; at some sites multiple, incipient A horizons were buried during waning valley-bottom aggradation. At two localities, the buried flood-plain is evident as a clay-rich stratum that must have been deposited in a paleochannel. Flood-plain stabilization between 5700 and 5100 cal. year BP probably occurred in response to the effects of external climate forcing on vegetation and hydrologic changes. Flood-plains of other rivers in the central Great Plains also stabilized at this time, further supporting a climatic explanation for slowing of valley aggradation and formation of a flood-plain at this time. Recognition of buried flood-plains is important to both soil mapping in valleys and to the discovery of cultural resources in valleys.

  2. Modelling long-term sediment deposition in a river floodplain during continues flood events

    NASA Astrophysics Data System (ADS)

    Guan, Mingfu; Ahilan, Sangaralingam; Wright, Nigel; Sleigh, P. Andrew

    2015-04-01

    River floodplains act as a form of storage during high discharges in a river. As a floodplain generally has a lower energy environment, sediment aggradation commonly occurs over the period of time, which will reduce the overall storage capacity of the floodplain. Also, in a river system sediments are generally considered as the carrier of pesticides and metal contamination from the upstream catchment. Hence, studying sediment deposition in a floodplain is not only helpful for local flood risk assessment, but also can improve our understanding of the dispersion of contaminants associated with the transfer of sediment between a river and its floodplain. This study adopts a recently updated two-dimensional hydro-morphodynamic model based on the full shallow water equations to model a long-term spatial migration of Johnson Creek, Portland, Oregon and its floodplain. The 500-year, 100-year, 50-year, 10-year, as well as the recorded flood events during 1941-2014 were simulated. Suspended load with three grain-sizes was transported to the river along with the floods. The results indicate that about 30 - 45% of total sediment load is deposited in the floodplain for the studied return period floods. The spatial distribution and amount of short and long-term sediment deposition on the floodplain is demonstrated, and the resulting potential loss of flood storage capacity is analysed and discussed.

  3. Importance of floodplain connectivity to fish populations in the Apalachicola River, Florida

    USGS Publications Warehouse

    Burgess, O.T.; Pine, William E.; Walsh, S.J.

    2013-01-01

    Floodplain habitats provide critical spawning and rearing habitats for many large-river fishes. The paradigm that floodplains are essential habitats is often a key reason for restoring altered rivers to natural flow regimes. However, few studies have documented spatial and temporal utilization of floodplain habitats by adult fish of sport or commercial management interest or assessed obligatory access to floodplain habitats for species' persistence. In this study, we applied telemetry techniques to examine adult fish movements between floodplain and mainstem habitats, paired with intensive light trap sampling of larval fish in these same habitats, to assess the relationships between riverine flows and fish movement and spawning patterns in restored and unmodified floodplain distributaries of the Apalachicola River, Florida. Our intent is to inform resource managers on the relationships between the timing, magnitude and duration of flow events and fish spawning as part of river management actions. Our results demonstrate spawning by all study species in floodplain and mainstem river habitat types, apparent migratory movements of some species between these habitats, and distinct spawning events for each study species on the basis of fish movement patterns and light trap catches. Additionally, Micropterus spp., Lepomis spp. and, to a lesser degree, Minytrema melanops used floodplain channel habitat that was experimentally reconnected to the mainstem within a few weeks of completing the restoration. This result is of interest to managers assessing restoration activities to reconnect these habitats as part of riverine restoration programmes globally.

  4. Biogeography of sulfate-reducing prokaryotes in river floodplains.

    PubMed

    Miletto, Marzia; Loy, Alexander; Antheunisse, A Martijn; Loeb, Roos; Bodelier, Paul L E; Laanbroek, Hendrikus J

    2008-06-01

    In this study, a large-scale field survey was conducted to describe the biogeography of sulfate-reducing prokaryotes (SRPs) in river floodplains. Fingerprints obtained with three methods, i.e. 16S rRNA gene-based oligonucleotide microarray, dsrB-based denaturing gradient gel electrophoresis (DGGE) and polar lipid-derived fatty acid (PLFA) analyses, were used as a proxy to describe the SRPs community diversity. Each set of profiles was subjected to a combined multivariate/correlation analysis in order to compare SRP community profiles and to highlight the environmental variables influencing the SRPs distribution along environmental gradients. Floodplain soils harbored distinct SRP communities displaying biogeographic patterns. Nearly all profiles from the tidal sites consistently separated from the nontidal sites, independently from the screening method and the multivariate statistics used. The distribution of the microarray/DGGE/PLFA-based fingerprints in the principal component plots could be correlated to eight soil variables, i.e. soil organic matter, total nitrogen, total phosphorous and total potassium, and extractable ammonium, nitrate, phosphate and sulfate, as well as seven pore water variables, i.e. phosphate, sulfate, sulfide, chloride, sodium, potassium and magnesium ions. Indication of a salinity- and plant nutrient-dependent distribution of SRPs related to Desulfosarcina, Desulfomonile and Desulfobacter was suggested by microarray, DGGE and PLFA analyses.

  5. Changes in lowland floodplain sedimentation processes: pre-disturbance to post-rehabilitation, Cosumnes River, CA

    NASA Astrophysics Data System (ADS)

    Florsheim, Joan L.; Mount, Jeffrey F.

    2003-12-01

    During the late Holocene, sediment deposition on the lowland Cosumnes River floodplain, CA has depended on factors that varied temporally and spatially, such as basin subsidence, sea level rise, flow, and sediment supply from both the Sacramento River system and from the Cosumnes River system itself, and anthropogenic changes. Through field investigations and analyses of historical maps, bridge core logs, and sediment size distributions, we link hydrogeomorphic processes to three stages of floodplain sedimentation on the lowland Cosumnes River. Stage I (1000-200 YBP) combined late Holocene pre-disturbance flood basin overflow and anastomosing river processes deposited spatially variable sediment consisting of gray-blue clay (87% clay) interlayered with relatively thin coarser sediment. Pre-disturbance Holocene deposition rates of up to ˜3.0 mm/year kept pace with sea level rise and tectonic basin subsidence. Stage II (200 to ˜10 YBP) anthropogenic disturbances caused a rapid increase in floodplain sedimentation rates up to 25 mm/year between 1849 and ˜1920, and deposited a relatively coarser reddish-brown sandy clay (˜40% clay) layer that overlies the basin deposits. Between ˜1920 and 1990 AD, sedimentation was greatly limited on the lower Cosumnes floodplain because levees inhibited connectivity between both the Sacramento and Cosumnes River systems and the Cosumnes floodplain. During this stage, the density of channel segments in the anastomosing river floodplain decreased by 30% as agricultural activities filled secondary channels and leveled floodplain topography. During Stage III (˜10 YBP to the present), post-rehabilitation floodplain sand splay complex sediment deposited after 1998 AD resulted from intentionally breaching levees to promote habitat at the Cosumnes River Preserve. The splay complex is dominated by medium to very coarse sand with finer intervening layers. The post-rehabilitation splay complex overlies the older basin deposits in a

  6. Spatial Patterns in Biofilm Diversity across Hierarchical Levels of River-Floodplain Landscapes.

    PubMed

    Peipoch, Marc; Jones, Ryan; Valett, H Maurice

    2015-01-01

    River-floodplain systems are among the most diverse and productive ecosystems, but the effects of biophysical complexity at multiple scales on microbial biodiversity have not been studied. Here, we investigated how the hierarchical organization of river systems (i.e., region, floodplain, zone, habitats, and microhabitats) influences epilithic biofilm community assemblage patterns by characterizing microbial communities using 16S rRNA gene sequence data and analyzing bacterial species distribution across local and regional scales. Results indicate that regional and local environmental filters concurrently sort bacterial species, suggesting that spatial configuration of epilithic biofilms resembles patterns of larger organisms in floodplain ecosystems. Along the hierarchical organization of fluvial systems, floodplains constitute a vector of maximum environmental heterogeneity and consequently act as a major landscape filter for biofilm species. Thus, river basins and associated floodplains may simply reflect very large scale 'patches' within which environmental conditions select for community composition of epilithic biofilms.

  7. Spatial Patterns in Biofilm Diversity across Hierarchical Levels of River-Floodplain Landscapes

    PubMed Central

    Peipoch, Marc; Jones, Ryan; Valett, H. Maurice

    2015-01-01

    River-floodplain systems are among the most diverse and productive ecosystems, but the effects of biophysical complexity at multiple scales on microbial biodiversity have not been studied. Here, we investigated how the hierarchical organization of river systems (i.e., region, floodplain, zone, habitats, and microhabitats) influences epilithic biofilm community assemblage patterns by characterizing microbial communities using 16S rRNA gene sequence data and analyzing bacterial species distribution across local and regional scales. Results indicate that regional and local environmental filters concurrently sort bacterial species, suggesting that spatial configuration of epilithic biofilms resembles patterns of larger organisms in floodplain ecosystems. Along the hierarchical organization of fluvial systems, floodplains constitute a vector of maximum environmental heterogeneity and consequently act as a major landscape filter for biofilm species. Thus, river basins and associated floodplains may simply reflect very large scale ‘patches’ within which environmental conditions select for community composition of epilithic biofilms. PMID:26630382

  8. Spatial Patterns in Biofilm Diversity across Hierarchical Levels of River-Floodplain Landscapes.

    PubMed

    Peipoch, Marc; Jones, Ryan; Valett, H Maurice

    2015-01-01

    River-floodplain systems are among the most diverse and productive ecosystems, but the effects of biophysical complexity at multiple scales on microbial biodiversity have not been studied. Here, we investigated how the hierarchical organization of river systems (i.e., region, floodplain, zone, habitats, and microhabitats) influences epilithic biofilm community assemblage patterns by characterizing microbial communities using 16S rRNA gene sequence data and analyzing bacterial species distribution across local and regional scales. Results indicate that regional and local environmental filters concurrently sort bacterial species, suggesting that spatial configuration of epilithic biofilms resembles patterns of larger organisms in floodplain ecosystems. Along the hierarchical organization of fluvial systems, floodplains constitute a vector of maximum environmental heterogeneity and consequently act as a major landscape filter for biofilm species. Thus, river basins and associated floodplains may simply reflect very large scale 'patches' within which environmental conditions select for community composition of epilithic biofilms. PMID:26630382

  9. Hydrologic and geomorphic considerations in restoration of river-floodplain connectivity in a highly altered river system, Lower Missouri River, USA

    USGS Publications Warehouse

    Jacobson, Robert B.; Janke, Tyler P.; Skold, Jason J.

    2011-01-01

    Planning for restoration of river-floodplain systems requires understanding how often and how much of a floodplain may be inundated, and how likely the floodplain is to retain the water once flooded. These factors depend fundamentally on hydrology and geomorphology of the channel and floodplain. We discuss application of an index of river-floodplain connectivity, the Land Capability Potential Index (LCPI), to regional-scale restoration planning along 600 km of the Lower Missouri River. The LCPI integrates modeled water-surface elevations, floodplain topography, and soils to index relative wetness of floodplain patches. Geomorphic adjustment of the Lower Missouri River to impoundment and channel engineering has altered the natural relations among hydrology, geomorphology, and floodplain soils, and has resulted in a regional upstream to downstream gradient in connectivity potential. As a result, flow-regime management is limited in its capacity to restore floodplain ecosystems. The LCPI provides a tool for identifying and mapping floodplain restoration potential, accounting for the geomorphic adjustment. Using simple criteria, we illustrate the utility of LCPI-like approaches in regional planning for restoration of plains cottonwood (Populus deltoides) communities, hydrologically connected floodplain wetlands, and seasonal floodplain wetlands.

  10. Modelling nitrogen retention in floodplains with different degrees of degradation for three large rivers in Germany.

    PubMed

    Natho, S; Venohr, M; Henle, K; Schulz-Zunkel, C

    2013-06-15

    Floodplains perform a variety of ecosystem functions and services - more than many other ecosystems. One of these ecosystem services is the reduction in nitrogen (N) loads and a subsequent improvement to the water quality. Since diffuse and also point nitrogen sources continue to cause a variety of problems in rivers and floodplains, inundated floodplains could act as net sinks for N and are therefore of great importance throughout Germany and Europe. This study analyses the effects of riparian floodplains on N-retention on the landscape scale for three large river systems with different degrees of degradation. Two approaches, differing in terms of the complexity of their respective input data and methods, were applied under wet and dry conditions. Whereas the proxy-based approach considers proxy values for N-retention, the model-based approach accounts for event-driven dynamic input data such as the extent of the inundated floodplain and incoming loads. Comparing the results of the two approaches it can be observed that floodplains of the near-natural river can retain up to 4% of the river load under wet conditions. During such conditions N-retention in floodplains is similar to that of rivers. For the two other floodplains, the results of the two approaches were quite different, showing lower N-retention capacities. However, for these floodplains as well, both approaches are suitable for calculating measurable N-retention rates, which is an important result because it also suggests that even degraded floodplains still preserve this particular ecosystem function and therefore still contribute to improving the quality of river water.

  11. EXPLOITATION OF FLOODPLAIN RESOURCES BY ADULT LARGESCALE SUCKER OF THE WILLAMETTE RIVER, OREGON

    EPA Science Inventory

    We tested two predictions of the flood-pulse concept on a large, temperate alluvial river that historically flooded an extensive fringing floodplain. We predicted adult largescale sucker, Catostomus macrocheilus, would: (1) migrate onto the floodplain during high water; and (2) e...

  12. Assessment of floodplain vulnerability during extreme Mississippi River flood 2011.

    PubMed

    Goodwell, Allison E; Zhu, Zhenduo; Dutta, Debsunder; Greenberg, Jonathan A; Kumar, Praveen; Garcia, Marcelo H; Rhoads, Bruce L; Holmes, Robert R; Parker, Gary; Berretta, David P; Jacobson, Robert B

    2014-01-01

    Regional change in the variability and magnitude of flooding could be a major consequence of future global climate change. Extreme floods have the capacity to rapidly transform landscapes and expose landscape vulnerabilities through highly variable spatial patterns of inundation, erosion, and deposition. We use the historic activation of the Birds Point-New Madrid Floodway during the Mississippi and Ohio River Flooding of 2011 as a scientifically unique stress experiment to analyze indicators of floodplain vulnerability. We use pre- and postflood airborne Light Detection and Ranging data sets to locate erosional and depositional hotspots over the 540 km(2) agricultural Floodway. While riparian vegetation between the river and the main levee breach likely prevented widespread deposition, localized scour and deposition occurred near the levee breaches. Eroded gullies nearly 1 km in length were observed at a low ridge of a relict meander scar of the Mississippi River. Our flow modeling and spatial mapping analysis attributes this vulnerability to a combination of erodible soils, flow acceleration associated with legacy fluvial landforms, and a lack of woody vegetation to anchor soil and enhance flow resistance. Results from this study could guide future mitigation and adaptation measures in cases of extreme flooding.

  13. Assessment of floodplain vulnerability during extreme Mississippi River flood 2011.

    PubMed

    Goodwell, Allison E; Zhu, Zhenduo; Dutta, Debsunder; Greenberg, Jonathan A; Kumar, Praveen; Garcia, Marcelo H; Rhoads, Bruce L; Holmes, Robert R; Parker, Gary; Berretta, David P; Jacobson, Robert B

    2014-01-01

    Regional change in the variability and magnitude of flooding could be a major consequence of future global climate change. Extreme floods have the capacity to rapidly transform landscapes and expose landscape vulnerabilities through highly variable spatial patterns of inundation, erosion, and deposition. We use the historic activation of the Birds Point-New Madrid Floodway during the Mississippi and Ohio River Flooding of 2011 as a scientifically unique stress experiment to analyze indicators of floodplain vulnerability. We use pre- and postflood airborne Light Detection and Ranging data sets to locate erosional and depositional hotspots over the 540 km(2) agricultural Floodway. While riparian vegetation between the river and the main levee breach likely prevented widespread deposition, localized scour and deposition occurred near the levee breaches. Eroded gullies nearly 1 km in length were observed at a low ridge of a relict meander scar of the Mississippi River. Our flow modeling and spatial mapping analysis attributes this vulnerability to a combination of erodible soils, flow acceleration associated with legacy fluvial landforms, and a lack of woody vegetation to anchor soil and enhance flow resistance. Results from this study could guide future mitigation and adaptation measures in cases of extreme flooding. PMID:24512322

  14. Assessment of floodplain vulnerability during extreme Mississippi River flood 2011

    USGS Publications Warehouse

    Goodwell, Allison E.; Zhu, Zhenduo; Dutta, Debsunder; Greenberg, Jonathan A.; Kumar, Praveen; Garcia, Marcelo H.; Rhoads, Bruce L.; Holmes, Jr., Robert R.; Parker, Gary; Berretta, David P.; Jacobson, Robert B.

    2014-01-01

    Regional change in the variability and magnitude of flooding could be a major consequence of future global climate change. Extreme floods have the capacity to rapidly transform landscapes and expose landscape vulnerabilities through highly variable spatial patterns of inundation, erosion, and deposition. We use the historic activation of the Birds Point-New Madrid Floodway during the Mississippi and Ohio River Flooding of 2011 as a scientifically unique stress experiment to analyze indicators of floodplain vulnerability. We use pre- and postflood airborne Light Detection and Ranging data sets to locate erosional and depositional hotspots over the 540 km2 agricultural Floodway. While riparian vegetation between the river and the main levee breach likely prevented widespread deposition, localized scour and deposition occurred near the levee breaches. Eroded gullies nearly 1 km in length were observed at a low ridge of a relict meander scar of the Mississippi River. Our flow modeling and spatial mapping analysis attributes this vulnerability to a combination of erodible soils, flow acceleration associated with legacy fluvial landforms, and a lack of woody vegetation to anchor soil and enhance flow resistance. Results from this study could guide future mitigation and adaptation measures in cases of extreme flooding.

  15. Removal of river embankments and the modelled effects on river-floodplain hydrodynamics

    NASA Astrophysics Data System (ADS)

    Clilverd, Hannah; Thompson, Julian; Heppell, Kate; Sayer, Carl; Axmacher, Jan

    2015-04-01

    The channelization and embankment of rivers has led to major ecological degradation of aquatic habitats worldwide. River restoration, which often includes the removal of previously constructed barriers between a river and its floodplain, is now being widely used to create favourable hydrological conditions for target species or processes. However the effects of river restoration on hydraulic and hydrological processes are complex, and are often difficult to determine due to the infrequency of long-term monitoring programmes before and after restoration works. To examine the hydrological impacts of embankment removal under a variety of possible hydrological conditions, we developed coupled hydrological/hydraulic models of pre-embankment and post-embankment conditions at a wet grassland meadow in Norfolk, UK using the MIKE-SHE/MIKE 11 system. Groundwater hydrology and climate were monitored between 2007 and 2010 with river inflows being provided from an upstream gauging station. The embanked model was calibrated and validated with observed groundwater data for two consecutive 12-month periods, after which the restored topography was applied to the model and validated for a subsequent 12-month period. The restored model was then run for the same period as the embanked model (i.e. with the same river inflow, precipitation, and potential evapotranspiration data) to remove interannual climate variability and enable a direct comparison between models. Modelled groundwater levels compared well with piezometer observations and reproduced the observed rapid groundwater response to high magnitude rainfall and river flow events. Removal of the embankments resulted in frequent localised flooding at the river edge, widespread floodplain inundation at flows greater than 1.9 m3 sec-1, as well as higher groundwater levels and greater subsurface storage. Restoration had only a minor effect on flood peak attenuation (maximum 5% flood peak reduction), likely due to the small size of

  16. Spatial patterns of aquatic habitat richness in the Upper Mississippi River floodplain, USA

    USGS Publications Warehouse

    De Jager, Nathan R.; Rohweder, Jason J.

    2012-01-01

    Interactions among hydrology and geomorphology create shifting mosaics of aquatic habitat patches in large river floodplains (e.g., main and side channels, floodplain lakes, and shallow backwater areas) and the connectivity among these habitat patches underpins high levels of biotic diversity and productivity. However, the diversity and connectivity among the habitats of most floodplain rivers have been negatively impacted by hydrologic and structural modifications that support commercial navigation and control flooding. We therefore tested the hypothesis that the rate of increase in patch richness (# of types) with increasing scale reflects anthropogenic modifications to habitat diversity and connectivity in a large floodplain river, the Upper Mississippi River (UMR). To do this, we calculated the number of aquatic habitat patch types within neighborhoods surrounding each of the ≈19 million 5-m aquatic pixels of the UMR for multiple neighborhood sizes (1–100 ha). For all of the 87 river-reach focal areas we examined, changes in habitat richness (R) with increasing neighborhood length (L, # pixels) were characterized by a fractal-like power function R = Lz (R2 > 0.92 (P z) measures the rate of increase in habitat richness with neighborhood size and is related to a fractal dimension. Variation in z reflected fundamental changes to spatial patterns of aquatic habitat richness in this river system. With only a few exceptions, z exceeded the river-wide average of 0.18 in focal areas where side channels, contiguous floodplain lakes, and contiguous shallow-water areas exceeded 5%, 5%, and 10% of the floodplain respectively. In contrast, z was always less than 0.18 for focal areas where impounded water exceeded 40% of floodplain area. Our results suggest that rehabilitation efforts that target areas with <5% of the floodplain in side channels, <5% in floodplain lakes, and/or <10% in shallow-water areas could improve habitat diversity across multiple scales in the UMR.

  17. Floodplain biogeochemical processing of floodwaters in the Atchafalaya River Basin during the Mississippi River flood of 2011

    USGS Publications Warehouse

    Scott, Durelle T.; Keim, Richard F.; Edwards, Brandon L.; Jones, C. Nathan; Kroes, Daniel E.

    2014-01-01

    The 2011 flood in the Lower Mississippi resulted in the second highest recorded river flow diverted into the Atchafalaya River Basin (ARB). The higher water levels during the flood peak resulted in high hydrologic connectivity between the Atchafalaya River and floodplain, with up to 50% of the Atchafalaya River water moving off channel. Water quality samples were collected throughout the ARB over the course of the flood event. Significant nitrate (NO3-) reduction (75%) occurred within the floodplain, resulting in a total NO3- reduction of 16.6% over the flood. The floodplain was a small but measurable source of dissolved reactive phosphorus (SRP) and ammonium (NH4+). Collectively, these results from this large flood event suggest that enhancing river-floodplain connectivity through freshwater diversions will reduce NO3- loads to the Gulf of Mexico during large annual floods.

  18. The Potential for Dams to Impact Lowland Meandering River Floodplain Geomorphology

    PubMed Central

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

    2014-01-01

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

  19. Influence of flow variability on floodplain formation and destruction, Little Missouri River, North Dakota

    USGS Publications Warehouse

    Miller, J.R.; Friedman, J.M.

    2009-01-01

    Resolving observations of channel change into separate planimetric measurements of floodplain formation and destruction reveals distinct relations between these processes and the flow regime. We analyzed a time sequence of eight bottomland images from 1939 to 2003 along the Little Missouri River, North Dakota, to relate geomorphic floodplain change to flow along this largely unregulated river. At the decadal scale, floodplain formation and destruction varied independently. Destruction was strongly positively correlated with the magnitude of infrequent high flows that recur every 5-10 yr, whereas floodplain formation was negatively correlated with the magnitude of frequent low flows exceeded 80% of the time. At the century scale, however, a climatically induced decrease in peak flows has reduced the destruction rate, limiting the area made available for floodplain formation. The rate of destruction was not uniform across the floodplain. Younger surfaces were consistently destroyed at a higher rate than older surfaces, suggesting that throughput of contaminants would have occurred more rapidly than predicted by models that assume uniform residence time of sediment across the floodplain. Maps of floodplain ages produced by analysis of sequential floodplain images are similar to maps of forest ages produced through dendrochronology, confirming the assumption of dendrogeomorphic studies that riparian tree establishment in this system is limited to recent channel locations. ?? 2009 Geological Society of America.

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

    PubMed

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

  2. Patterns of Ground Water Movement in a Portion of the Willamette River Floodplain, Oregon

    EPA Science Inventory

    In reaches unconstrained by revetments, the Willamette River and its floodplain along its lowland mainstem is a continually evolving system. Several channel reconstruction and restoration projects have been implemented or planned in order to obtain beneficial services along the r...

  3. Floodplain Formation and Cottonwood Colonization Patterns on the Willamette River, Oregon, USA.

    PubMed

    Dykaar; Wigington

    2000-01-01

    / Using a series of aerial photographs taken between 1936 and 1996, we trace coevolution of floodplain and riparian forest on the Willamette River. Within-channel barforms appear to be the predominant incipient floodplain landform and habitat for primary succession. Interlinked development of bar(s) and erosion of near banks, filling of channels, and establishment and growth of cottonwoods and willows results in coalescence with older floodplain. Sizeand internal structure of riparian forest patches reflect evolution of underlying barforms or channel beds. Floodplain matures as the active channel migrates away by repetition of the bar formation and near-bank erosion process, or is progressively abandoned by infilling and/or constriction with a bar. Other parts of the floodplain are recycled as eroding banks provide the coarse sediment and large woody debris for building new bars. A multichannel planform is maintained as building bars split flow; channels lengthen as bars and islands join into larger assemblages. Avulsion appears to cut new channels only short distances. Given the central role of bars and islands in building new floodplain habitat, we identify their area as a geomorphic indicator of river-floodplain integrity. We measure an 80% decline in bar and island area between 1910 and 1988 within a 22-km section. Dams, riprap, logging, and gravel mining may all be contributing to diminished bar formation rates. Removing obstacles to natural riparian forest creation mechanisms is necessary to regenerate the river-floodplain system and realize its productive potential. PMID:10552104

  4. Floodplain storage of mine tailings in the Belle Fourche river system: a sediment budget approach

    USGS Publications Warehouse

    Marron, D.C.

    1992-01-01

    Arsenic-contaminated mine tailings that were discharged into Whitewood Creek at Lead, South Dakota, from 1876 to 1978, were deposited along the floodplains of Whitewood Creek and the Belle Fourche River. The resulting arsenic-contaminated floodplain deposit consists mostly of overbank sediments and filled abandoned meanders along Whitewood Creek, and overbank and point-bar sediments along the Belle Fourche River. Arsenic concentrations of the contaminated sediments indicate the degree of dilution of mine tailings by uncontaminated alluvium. About 13% of the 110 ?? 106 Mg of mine tailings that were discharged at Lead were deposited along the Whitewood Creek floodplain. -from Author

  5. Coupling of groundwater, river flow and rainfall in an upland floodplain

    NASA Astrophysics Data System (ADS)

    Archer, Nicole; Dochartaigh, Brighid Ó.; MacDonald, Alan; Bonell, Mike; Black, Andrew; Coles, Neil

    2014-05-01

    Upland floodplains provide an important function in regulating river flows and controlling the coupling of hillslope runoff with rivers. To investigate the responses of floodplain groundwater to river flows and rainfall events, a small floodplain in an upland area of the River Tweed catchment, Scotland, was characterised using geophysics, 3D geological mapping and hydrogeological testing; and monitoring undertaken from September 2011 to February 2013 of: groundwater levels in five pairs of piezometers; river stage and flow at the upstream and downstream limits of the study site; soil moisture on the adjacent hillslope; and meteorological parameters. Periodical groundwater chemistry and residence data were also collected. The floodplain aquifer is permeable throughout but partially stratified, comprising dominantly alluvial and glaciofluvial sandy gravels between 8 and 15m interspersed with thin, intermittent layers of low permeability silts, clays and peats. Overlying the gravel aquifer is a partial thin cover of low permeability alluvial silts, and it is underlain dominantly by low permeability glaciolacustrine silts and clays. High permeability solifluction deposits mantle much of the adjacent hillslope and provide a rapid connection to the floodplain aquifer. The unusually wet year of 2012 provides a good example of how a temperate upland floodplain responds to consistently high rainfall. Statistical analysis and graphical interpretation of groundwater level, rainfall, soil moisture and river stage demonstrates that: 1) dominant groundwater flow within the floodplain is in the same direction as the river, from up-valley to down-valley; 2) soil moisture in the hillslope is strongly correlated with local rainfall, but groundwater across much of the floodplain is more strongly influenced by river stage; except 3) groundwater near the edge of floodplain, which responds more slowly to local rainfall and river stage changes ; and 4) subsurface flow from the hillslope

  6. Strategic floodplain reconnection for the Lower Tisza River, Hungary: Opportunities for flood-height reduction and floodplain-wetland reconnection

    NASA Astrophysics Data System (ADS)

    Guida, Ross J.; Swanson, Taylor L.; Remo, Jonathan W. F.; Kiss, Timea

    2015-02-01

    During the late 19th Century, the Tisza River's vast floodplain-wetland system was largely disconnected by levees, facilitating "reclamation" for agriculture and resulting in an estimated loss of over 90% of historical wetlands. While levees have been successful in preventing catastrophic flooding for a century, Lower Tisza flood stage records have been set repeatedly during the last 15 years. The decrease in the Tisza's current floodway carrying capacity has reduced the flood-protection level of the Tisza's aging levee system. Recently in Hungary, "Room for the River" policies have gained more prominence. To explore the possibilities of a room for the river approach along the Lower Tisza, we assess eight potential floodplain-reconnection scenarios between Csongrád, Hungary and the Hungary-Serbia border. A novel framework using hydrodynamic and geospatial modeling was used to perform planning-level evaluations of the tradeoffs between floodplain-reconnection scenarios and enhancement of the existing levee system. The scenarios evaluated include levee removal and levee setbacks to strategically reconnect significant historical wetlands while reducing flood levels. Scenario costs and human population impacts are also assessed. Impacts of reconnecting the Lower Tisza floodplain are compared to heightening levees, the prevailing strategy over the previous century. From a purely construction-cost perspective, heightening Lower Tisza levees is potentially the most cost-effective and politically expedient solution (i.e., impacts the least number of people). However, levee-heightening does not solve the long-term problem of reduced flood conveyance, which has been attributed to aggradation and increased floodplain roughness, nor does it result in wetland reconnection or enhancement of other floodplain ecosystem services. The suite of reconnection options we evaluate provides engineers, planners, and decision makers a framework from which they can further evaluate

  7. Hydraulic interactions between a meandering river channel and its floodplain during an overbank flood

    NASA Astrophysics Data System (ADS)

    Harrison, L.; Dunne, T.; Fisher, B.

    2012-12-01

    River channel and floodplain complexity is generated by the lateral migration of meandering river channels across the floodplain surface. The main driver of meander migration is the flow field which erodes the outer bank of river bends, scours pools, creates topographic variability on the floodplain and interacts with riparian vegetation. Flows between channels and floodplains are generally thought to be highly three-dimensional due to the presence of secondary circulation cells and helical flow patterns observed in laboratory experiments, yet few field datasets exist to test or validate existing conceptual models. Flow over and through floodplain vegetation has also been difficult to characterize at the field scale. We took advantage of a remarkably long and stable 5-year flood discharge to measure flow fields across the floodplain and in curved reaches of the gravel-bed Merced River In California to document the hydraulic interactions between the channel and floodplain. We then developed, calibrated and validated a quasi-3D hydrodynamic model of the flows in order to expand the interpretation of the results. Due to the spatial variability in both topography and flow resistance, the modeling required detailed mapping of the channel-floodplain surface and vegetation with a terrestrial LiDAR scanner and RTK GPS units. The results highlight several general aspects of the channel-floodplain flow during an overbank flow event: (1) the flow field in the channel was largely two-dimensional with only weak helical flow patterns; (2) the highest channel velocities and boundary shear stresses occurred at the local maxima in bend curvature where lateral migration has been documented via repeat topographic surveys; (3) flow velocities rapidly decelerated as water was decanted from the channel onto the floodplain where the velocity magnitude was roughly 20-30% of the average channel velocity; (4) dense vegetation along the channel margins enhanced channel velocities but reduced

  8. Survival tactics of Ranunculus species in river floodplains.

    PubMed

    He, J B; Bögemann, G M; van de Steeg, H M; Rijnders, J G; Voesenek, L A; Blom, C W

    1999-01-01

    The flooding resistance of four Ranunculus species was studied under controlled conditions and related to the tactics used by these species to survive in their natural habitat in river floodplains. R. bulbosus, a species from seldom-flooded river levées, was relatively intolerant of both waterlogging and complete submergence, due to a constitutively low level of aerenchyma in the root system. This lack of gas spaces resulted in high mortality rates during flooding treatments and an inability to use photosynthetically derived oxygen for root respiration during complete submergence. The pioneer R. sceleratus, predominantly abundant in low lying mudflats, was very resistant to waterlogging and shallow floods. Due to its constitutively high root porosity and its ability to greatly increase the elongation rate of petioles under water this species can ameliorate flooding stress. However, when leaf blades of R. sceleratus were unable to reach the water surface, this species died as quickly as the flooding-intolerant R. bulbosus. This indicates that fast elongation of petioles under water competes for energy and respirable reserves with maintenance processes. R. repens, a species from lower, frequently inundated floodplains, was very tolerant of prolonged waterlogging and submergence. Its high resistance to complete submergence under continuous darkness indicates that this species tolerates hypoxic and/or anoxic tissue conditions via metabolic adjustments. Lysigenous aerenchyma was also induced in the primary root system and in newly developed laterals, and it was able to use oxygen generated by underwater photosynthesis, for root respiration. R. acris, a species from less frequently flooded areas, was as resistant to waterlogging and submergence in the light as R. repens. However, it has a lower resistance than R. repens to complete submergence in the dark. A submergence pre-treatment increased the maximum net underwater photosynthetic rate in R. bulbosus, whereas a

  9. Carbon, nitrogen, and phosphorus accumulation in floodplains of Atlantic Coastal Plain rivers, USA

    USGS Publications Warehouse

    Noe, G.B.; Hupp, C.R.

    2005-01-01

    Net nutrient accumulation rates were measured in riverine floodplains of the Atlantic Coastal Plain in Virginia, Maryland, and Delaware, USA. The floodplains were located in watersheds with different land use and included two sites on the Chickahominy River (urban), one site on the Mattaponi River (forested), and five sites on the Pocomoke River (agricultural). The Pocomoke River floodplains lie along reaches with natural hydrogeomorphology and on reaches with restricted flooding due to channelization and levees. A network of feldspar clay marker horizons was placed on the sediment surface of each floodplain site 3-6 years prior to sampling. Sediment cores were collected from the material deposited over the feldspar clay pads. This overlying sediment was separated from the clay layer and then dried, weighed, and analyzed for its total carbon (C), nitrogen (N), and phosphorus (P) content. Mean C accumulation rates ranged from 61 to 212 g??m-2??yr-1, N accumulation rates ranged from 3.5 to 13.4 g??m -2??yr-1, and P accumulation rates ranged from 0.2 to 4.1 g??m-2??yr-1 among the eight floodplains. Patterns of intersite variation in mineral sediment and P accumulation rates were similar to each other, as was variation in organic sediment and C and N accumulation rates. The greatest sediment and C, N, and P accumulation rates were observed on Chickahominy River floodplains downstream from the growing metropolitan area of Richmond, Virginia. Nutrient accumulation rates were lowest on Pocomoke River floodplains that have been hydraulically disconnected from the main channel by channelization and levees. Sediment P concentrations and P accumulation rates were much greater on the hydraulically connected floodplain immediately downstream of the limit of channelization and dense chicken agriculture of the upper Pocomoke River watershed. These findings indicate that (1) watershed land use has a large effect on sediment and nutrient retention in floodplains, and (2) limiting

  10. Ecological validity of river-floodplain system assessment by planktonic crustacean survey (Branchiata: Branchiopoda).

    PubMed

    Illyová, Marta; Matečný, Igor

    2014-07-01

    Studies of the Slovakian Danube have indicated profound changes in the structures of several invertebrate assemblages in the section of the river bypassed by the Gabčíkovo hydroelectric project in 1992 and in adjacent floodplain water bodies. The present study investigates the relationship between hydrological connectivity and species diversity in the old main channel and adjacent left-bank water bodies, using resident cladocerans as indicators of the ecological integrity of the river-floodplain system. The work aimed to quantify cladoceran habitat preferences using habitat values (HV) and indication weights (IW) calculated from data accumulated during long-term monitoring of planktonic communities of the Danube floodplain (1,840.5-1,804 rkm) and supplemented with data from the literature. Although not listed as an indicator group in the European Union Water Framework Directive, cladocerans are shown to be highly apposite in the ecological assessment of river-floodplain systems. Of 71 recorded cladoceran species, 19 taxa showed a preference for eupotamal habitats, 24 species preferred eupotamal B/parapotamal waters, and 28 cladocerans were found to prefer the plesiopotamal/paleopotamal habitat type. Identified habitat types follow a gradient of hydrological connectivity with the main river channel, ranging from the eupotamal to more or less isolated floodplain water bodies. A secondary aim was to use the calculated values to assess the ecological integrity of the river-floodplain system. The key element of this procedure is the calculation of the Floodplain Index (FI) (Chovanec et al. Large Rivers, 15(1-4), 169-185 2005) from the summation of the habitat values and indication weights of all species present at the sampling sites. Calculated index values indicate the extent of disruption to lateral connectivity in the floodplain area.

  11. A procedure for incorporating spatial variability in ecological risk assessment of Dutch river floodplains.

    PubMed

    Kooistra, L; Leuven, R S; Nienhuis, P H; Wehrens, R; Buydens, L M

    2001-09-01

    Floodplain soils along the river Rhine in the Netherlands show a large spatial variability in pollutant concentrations. For an accurate ecological risk characterization of the river floodplains, this heterogeneity has to be included into the ecological risk assessment. In this paper a procedure is presented that incorporates spatial components of exposure into the risk assessment by linking geographical information systems (GIS) with models that estimate exposure for the most sensitive species of a floodplain. The procedure uses readily available site-specific data and is applicable to a wide range of locations and floodplain management scenarios. The procedure is applied to estimate exposure risks to metals for a typical foodweb in the Afferdensche and Deestsche Waarden floodplain along the river Waal, the main branch of the Rhine in the Netherands. Spatial variability of pollutants is quantified by overlaying appropriate topographic and soil maps resulting in the definition of homogeneous pollution units. Next to that, GIS is used to include foraging behavior of the exposed terrestrial organisms. Risk estimates from a probabilistic exposure model were used to construct site-specific risk maps for the floodplain. Based on these maps, recommendations for future management of the floodplain can be made that aim at both ecological rehabilitation and an optimal flood defense.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    A Geomorphic Analysis of Floodplain Lakes along the Embanked Lower Mississippi River for Managing Hydrologic Connectivity Floodplain lakes are vital to the environmental integrity of lowland rivers. Embankment by levees (dikes) for flood control greatly reduces the size of lowland floodplains and is detrimental to the quality and functioning of floodplain water bodies, presenting a challenge to government agencies charged with environmental management. The embanked floodplain of the Lower Mississippi River is an enormous surface which includes a variety of lake types formed by geomorphic and anthropogenic processes. While much is known about the channel and hydrologic regime, very little is known about the physical structure and functioning of the embanked floodplain of the lower Mississippi. Importantly, management agencies do not have an inventory of the basic characteristics (e.g., type, frequency, location, size, shape) of water bodies within the lower Mississippi embanked floodplain. An analysis of lakes along the Lower Mississippi River embanked floodplain is performed by utilizing the National Hydrographic Dataset (NHD) from the U.S. Geological Survey, a LiDAR digital elevation model (DEM), as well as streamflow data from the USGS. The vector NHD data includes every official mapped water body (blue line polygons) on USGS topographic maps at scales of 1:100,000 and 1:24,000. Collectively, we identify thousands of discreet water bodies within the embanked floodplain. Utilizing planimetric properties the water bodies were classified into the following lake types: cutoffs (neck and chute), sloughs, crevasse (scour), local drainage (topographic), and borrow pits. The data is then statistically analyzed to examine significant differences in the spatial variability in lake types along the entire lower Mississippi embanked floodplain in association with geomorphic divisions and hydrologic regime. The total embanked floodplain area of the LMR is 7,303 km2,. The total

  13. Using Cottonwood Dendrochronology to Reconstruct River Discharge and Floodplain Dynamics, Yellowstone River, Montana

    NASA Astrophysics Data System (ADS)

    Schook, D. M.; Friedman, J. M.; Rathburn, S. L.

    2014-12-01

    Ecosystems and societies worldwide have evolved to depend upon the timing and magnitude of river discharge, and understanding past flows can help guide modern water management. We used tree rings of riparian plains cottonwoods (Populus deltoides subsp. monilifera) to reconstruct the history of flow variation and channel migration of a 20 km reach of the Yellowstone River in eastern Montana. Dendrochronological flow reconstructions commonly use upland trees, but our study highlights the improved resolution when floodplain trees are integrated into the data set . Our sample of 240 cottonwoods dating back to 1751 permits flow reconstruction of the Yellowstone to before the voyage of Lewis and Clark. Our tree ring series intercorrelation coefficient is 0.58, and the ring width index correlates to annual discharge at R = 0.67. Flow reconstruction indicates that the decades of highest (1820s, 1850s) and lowest (1830s, 1900s) flows all occurred prior to the instrumental record, revealing the value of an extended perspective. Cottonwood age distribution indicates that, like other western rivers, the rate of channel migration on the Yellowstone declined in the 20th century. However, the Yellowstone uniquely lacks mainstem dams and substantial water extractions, revealing the occurrence of hydrological and ecological change on a relatively natural river. Our study reach is the most geomorphically active of the entire 1100 km river between Yellowstone National Park and the Missouri River, but cottonwood age distribution reveals that trees that have established since the 1960s are underrepresented. The lack of younger cottonwood trees is likely caused by a decline in river migration rates, which may be attributed to i) climate change directly leading to a decline in fluvial processes driving river migration, ii) a decoupling in the timing of the snowmelt runoff receding limb and cottonwood seed release, or iii) both. Even on this relatively unmodified river, it appears that

  14. Processesof Tamarix invasion and floodplain development along the lower Green River, Utah.

    PubMed

    Birken, Adam S; Cooper, David J

    2006-06-01

    Significant ecological, hydrologic, and geomorphic changes have occurred during the 20th century along many large floodplain rivers in the American Southwest. Native Populus forests have declined, while the exotic Eurasian shrub, Tamarix, has proliferated and now dominates most floodplain ecosystems. Photographs from late 19th and early 20th centuries illustrate wide river channels with largely bare in-channel landforms and shrubby higher channel margin floodplains. However, by the mid-20th century, floodplains supporting dense Tamarix stands had expanded, and river channels had narrowed. Along the lower Green River in eastern Utah, the causal mechanism of channel and floodplain changes remains ambiguous due to the confounding effects of climatically driven reductions in flood magnitude, river regulation by Flaming Gorge Dam, and Tamarix invasion. This study addressed whether Tamarix establishment and spread followed climate- or dam-induced reductions in annual peak flows or whether Tamarix was potentially a driver of floodplain changes. We aged 235 Tamarix and 57 Populus individuals, determined the hydrologic and geomorphic processes that controlled recruitment, identified the spatial relationships of germination sites within floodplain stratigraphic transects, and mapped woody riparian vegetation cohorts along three segments of the lower Green River. The oldest Tamarix established along several sampling reaches in 1938, and 1.50-2.25 m of alluvium has accreted above their germination surfaces. Nearly 90% of the Tamarix and Populus samples established during flood years that exceeded the 2.5-year recurrence interval. Recruitment was most common when large floods were followed by years with smaller peak flows. The majority of Tamarix establishment and Green River channel narrowing occurred long before river regulation by Flaming Gorge Dam. Tamarix initially colonized bare instream sand deposits (e.g., islands and bars), and most channel and floodplain changes

  15. Current status and restoration options for floodplains along the Danube River.

    PubMed

    Hein, Thomas; Schwarz, Ulrich; Habersack, Helmut; Nichersu, Iulian; Preiner, Stefan; Willby, Nigel; Weigelhofer, Gabriele

    2016-02-01

    Floodplains are key ecosystems of riverine landscapes and provide a multitude of ecosystem services. In most of the large river systems worldwide, a tremendous reduction of floodplain area has occurred in the last 100 years and this loss continues due to pressures such as land use change, river regulation, and dam construction. In the Danube River Basin, the extent of floodplains has been reduced by 68% compared to their pre-regulation area, with the highest losses occurring in the Upper Danube and the lowest in the Danube Delta. In this paper, we illustrate the restoration potential of floodplains along the Danube and its major tributaries. Via two case studies in the Upper and Lower Danube, we demonstrate the effects of restoration measures on the river ecosystem, addressing different drivers, pressures, and opportunities in these regions. The potential area for floodplain restoration based on land use and hydromorphological characteristics amounts to 8102 km(2) for the whole Danube River, of which estimated 75% have a high restoration potential. A comparison of floodplain status and options for restoration in the Upper and Lower Danube shows clear differences in drivers and pressures, but certain common options apply in both sections if the local context of stakeholders and societal needs are considered. New approaches to flood protection using natural water retention measures offer increased opportunities for floodplain restoration, but conflicting societal needs and legal frameworks may restrict implementation. Emerging issues such as climate change and invasive non-native species will need careful consideration in future restoration planning to minimize unintended effects and to increase the resilience of floodplains to these and other pressures.

  16. Current status and restoration options for floodplains along the Danube River.

    PubMed

    Hein, Thomas; Schwarz, Ulrich; Habersack, Helmut; Nichersu, Iulian; Preiner, Stefan; Willby, Nigel; Weigelhofer, Gabriele

    2016-02-01

    Floodplains are key ecosystems of riverine landscapes and provide a multitude of ecosystem services. In most of the large river systems worldwide, a tremendous reduction of floodplain area has occurred in the last 100 years and this loss continues due to pressures such as land use change, river regulation, and dam construction. In the Danube River Basin, the extent of floodplains has been reduced by 68% compared to their pre-regulation area, with the highest losses occurring in the Upper Danube and the lowest in the Danube Delta. In this paper, we illustrate the restoration potential of floodplains along the Danube and its major tributaries. Via two case studies in the Upper and Lower Danube, we demonstrate the effects of restoration measures on the river ecosystem, addressing different drivers, pressures, and opportunities in these regions. The potential area for floodplain restoration based on land use and hydromorphological characteristics amounts to 8102 km(2) for the whole Danube River, of which estimated 75% have a high restoration potential. A comparison of floodplain status and options for restoration in the Upper and Lower Danube shows clear differences in drivers and pressures, but certain common options apply in both sections if the local context of stakeholders and societal needs are considered. New approaches to flood protection using natural water retention measures offer increased opportunities for floodplain restoration, but conflicting societal needs and legal frameworks may restrict implementation. Emerging issues such as climate change and invasive non-native species will need careful consideration in future restoration planning to minimize unintended effects and to increase the resilience of floodplains to these and other pressures. PMID:26475242

  17. Zoogeography, taxonomy, and conservation of West Virginia's Ohio River floodplain crayfishes (Decapoda, Cambaridae).

    PubMed

    Loughman, Zachary J; Simon, Thomas P

    2011-01-01

    The crayfish fauna of West Virginia consists of 23 species and several undescribed taxa. Most survey efforts documenting this fauna have been conducted in lotic waterways throughout the Appalachian plateau, Allegheny Mountains, and Ridge and Valley physiographic provinces. Bottomland forests, swamps, and marshes associated with large river floodplain such as the Ohio River floodplain historically have been under-surveyed in the state. These habitats harbor the richest primary burrowing crayfish fauna in West Virginia, and are worthy of survey efforts. In an effort to fill this void, the crayfish fauna of West Virginia's Ohio River floodplain was surveyed from 2004 through 2009. From this survey, nine species from four genera were documented inhabiting the floodplain. Zoogeography, biology, and conservation status is provided for all nine crayfishes. The dominant genus along the floodplain is Cambarus, which includes Cambarus (Cambarus) carinirostris, Cambarus (Cambarus) bartonii cavatus, Cambarus (Procambarus) robustus and Cambarus (Tubericambarus) thomai. Cambarus (Tubericambarus) thomai is the most prevalent burrowing species occurring along the floodplain. The genus Orconectes consists of two native species, Orconectes (Cambarus) obscurus and Orconectes (Cambarus) sanbornii; and two invasive taxa, Orconectes (Gremicambarus) virilis and Orconectes (Procambarus) rusticus. Orconectes (Cambarus) obscurus has experienced a range extension to the south and occupies streams formerly occupied by Orconectes (Cambarus) sanbornii. Both invasive taxa were allied with anthropogenic habitats and disturbance gradients. The genera Fallicambarus and Procambarus are represented by a single species. Both Fallicambarus (Cambarus) fodiens and Procambarus (Orconectes) acutus are limited to the historic preglacial Marietta River Valley. PMID:21594135

  18. Zoogeography, taxonomy, and conservation of West Virginia’s Ohio River floodplain crayfishes (Decapoda, Cambaridae)

    PubMed Central

    Loughman, Zachary J.; Simon, Thomas P.

    2011-01-01

    Abstract The crayfish fauna of West Virginia consists of 23 species and several undescribed taxa. Most survey efforts documenting this fauna have been conducted in lotic waterways throughout the Appalachian plateau, Allegheny Mountains, and Ridge and Valley physiographic provinces. Bottomland forests, swamps, and marshes associated with large river floodplain such as the Ohio River floodplain historically have been under-surveyed in the state. These habitats harbor the richest primary burrowing crayfish fauna in West Virginia, and are worthy of survey efforts. In an effort to fill this void, the crayfish fauna of West Virginia’s Ohio River floodplain was surveyed from 2004 through 2009. From this survey, nine species from four genera were documented inhabiting the floodplain. Zoogeography, biology, and conservation status is provided for all nine crayfishes. The dominant genus along the floodplain is Cambarus, which includes Cambarus (Cambarus) carinirostris, Cambarus (Cambarus) bartonii cavatus, Cambarus (Procambarus) robustus and Cambarus (Tubericambarus) thomai. Cambarus (Tubericambarus) thomai is the most prevalent burrowing species occurring along the floodplain. The genus Orconectes consists of two native species, Orconectes (Cambarus) obscurus and Orconectes (Cambarus) sanbornii; and two invasive taxa, Orconectes (Gremicambarus) virilis and Orconectes (Procambarus) rusticus. Orconectes (Cambarus) obscurus has experienced a range extension to the south and occupies streams formerly occupied by Orconectes (Cambarus) sanbornii. Both invasive taxa were allied with anthropogenic habitats and disturbance gradients. The genera Fallicambarus and Procambarus are represented by a single species. Both Fallicambarus (Cambarus) fodiens and Procambarus (Orconectes) acutus are limited to the historic preglacial Marietta River Valley. PMID:21594135

  19. Songbird use of floodplain and upland forests along the Upper Mississippi River corridor during spring migration

    USGS Publications Warehouse

    Kirsch, Eileen M.; Heglund, Patricia J.; Gray, Brian R.; Mckann, Patrick

    2013-01-01

    The Upper Mississippi River is thought to provide important stopover habitat for migrating landbirds because of its north-south orientation and floodplain forests. The river flows through the Driftless Area of southwestern Wisconsin and southeastern Minnesota where forests are plentiful, yet forests of the floodplain and Driftless Area uplands differ greatly in landscape setting, tree species composition, and topography. We compared landbird assemblages in these upland and floodplain forests over three springs, 2005–2007, using line-transect surveys at randomly selected areas in and within 16 km of the floodplain. We found more species of both transient and locally breeding migrants per survey in floodplain than in upland forest. Detections of transient neotropical migrants did not differ statistically by habitat. Detections of locally breeding neotropical and temperate-zone migrants and transient temperate-zone migrants were greater in floodplain than in upland forest. Between floodplain and upland forest, assemblages of locally breeding species, including neotropical and temperate-zone migrants (of which some individuals were in transit), differed substantially, but assemblages of transients (including both neotropical and temperate-zone migrants) did not differ as much. Only two species of transient migrants had clear affinities for floodplain forest, and none had an affinity for upland forest, whereas most locally breeding migrants had an affinity for either upland or floodplain forest. Within each spring, however, detections of transient neotropical migrants shifted from being greater in floodplain to greater in upland forests. This intraseasonal shift may be related to the phenology of certain tree species.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  1. Floodplain evolution in a confluence zone: Paraná and Ivaí rivers, Brazil

    NASA Astrophysics Data System (ADS)

    Morais, Eduardo Souza de; Santos, Manoel Luis dos; Cremon, Édipo Henrique; Stevaux, José Cândido

    2016-03-01

    In this study we investigated floodplain development at the confluence of the Paraná and Ivaí rivers, Brazil. We evaluated paleochannels with sedimentary facies and morphometry from cartographic products, which enabled us to identify compartments that indicate homologous morphogenesis. These results contributed to the distinction in the floodplain of areas reworked by the Paraná, Ivaí, or both river systems. Additionally, investigations that included dating deposits on the terrace that borders the floodplain and an alluvial fan (also in contact with the floodplain) reinforced the interpretation of the fluvial landscape. The identified stages of geomorphological evolution demonstrated the existence of a paleoconfluence of the Paraná and Ivaí rivers during the late Pleistocene that was located 6 km upstream from the current confluence. This paleoconfluence displays a different configuration in relation to the current confluence, and its features resemble and contribute to understanding the former braided channel pattern of the Paraná River. The abandonments of the Paraná River channels identified in this study were initial and crucial process in the development of the floodplain. This channel change favored the formation of extensive wetlands and consequently the confluence migration, which resulted in the fluvial reworking indicated by the paleochannels of the Ivaí River. Another implication from the confluence migration was a base level fall, which contributed to maintaining the stability of the Ivaí River and its embedded meanders. In addition, investigations of an alluvial fan in the Paraná River valley provided evidence of massive deposition of sediments from a tributary of the Ivaí River onto the floodplain, which is associated with a regional dry period in the late Holocene as well as neotectonic control.

  2. Geomorphology and flood-plain vegetation of the Sprague and lower Sycan Rivers, Klamath Basin, Oregon

    USGS Publications Warehouse

    O'Connor, James E.; McDowell, Patricia F.; Lind, Pollyanna; Rasmussen, Christine G.; Keith, Mackenzie K.

    2015-01-01

    Despite these effects of human disturbances, many of the fundamental physical processes forming the Sprague River fluvial systems over the last several thousand years still function. In particular, flows are unregulated, sediment transport processes are active, and overbank flooding allows for floodplain deposition and erosion. Therefore, restoration of many of the native physical conditions and processes is possible without substantial physical manipulation of current conditions for much of the Sprague River study area. An exception is the South Fork Sprague River, where historical trends are not likely to reverse until it attains a more natural channel and flood-plain geometry and the channel aggrades to the extent that overbank flow becomes common.

  3. Past and predicted future changes in the land cover of the Upper Mississippi River floodplain, USA

    USGS Publications Warehouse

    De Jager, N. R.; Rohweder, J.J.; Nelson, J.C.

    2013-01-01

    This study provides one historical and two alternative future contexts for evaluating land cover modifications within the Upper Mississippi River (UMR) floodplain. Given previously documented changes in land use, river engineering, restoration efforts and hydro-climatic changes within the UMR basin and floodplain, we wanted to know which of these changes are the most important determinants of current and projected future floodplain land cover. We used Geographic Information System data covering approximately 37% of the UMR floodplain (3232 km2) for ca 1890 (pre-lock and dam) and three contemporary periods (1975, 1989 and 2000) across which river restoration actions have increased and hydro-climatic changes have occurred. We further developed two 50-year future scenarios from the spatially dependent land cover transitions that occurred from 1975 to 1989 (scenario A) and from 1989 to 2000 (scenario B) using Markov models.Land cover composition of the UMR did not change significantly from 1975 to 2000, indicating that current land cover continues to reflect historical modifications that support agricultural production and commercial navigation despite some floodplain restoration efforts and variation in river discharge. Projected future land cover composition based on scenario A was not significantly different from the land cover for 1975, 1989 or 2000 but was different from the land cover of scenario B, which was also different from all other periods. Scenario B forecasts transition of some forest and marsh habitat to open water by the year 2050 for some portions of the northern river and projects that some agricultural lands will transition to open water in the southern portion of the river. Future floodplain management and restoration planning efforts in the UMR should consider the potential consequences of continued shifts in hydro-climatic conditions that may occur as a result of climate change and the potential effects on floodplain land cover.

  4. Large scale distribution of bacterial communities in the upper Paraná River floodplain

    PubMed Central

    Chiaramonte, Josiane Barros; Roberto, Maria do Carmo; Pagioro, Thomaz Aurélio

    2014-01-01

    A bacterial community has a central role in nutrient cycle in aquatic habitats. Therefore, it is important to analyze how this community is distributed throughout different locations. Thirty-six different sites in the upper Paraná River floodplain were surveyed to determine the influence of environmental variable in bacterial community composition. The sites are classified as rivers, channels, and floodplain lakes connected or unconnected to the main river channel. The bacterial community structure was analyzed by fluorescent in situ hybridization (FISH) technique, based on frequency of the main domains Bacteria and Archaea, and subdivisions of the phylum Proteobacteria (Alpha-proteobacteria, Beta-proteobacteria, Gamma-proteobacteria) and the Cytophaga-Flavobacterium cluster. It has been demonstrated that the bacterial community differed in density and frequency of the studied groups. And these differences responded to distinct characteristics of the three main rivers of the floodplain as well as to the classification of the environments found in this floodplain. We conclude that dissimilarities in the bacterial community structure are related to environmental heterogeneity, and the limnological variables that most predicted bacterial communities in the upper Paraná River floodplain was total and ammoniacal nitrogen, orthophosphate and chlorophyll-a. PMID:25763022

  5. Analysis of floodplain storage and sedimentation in the middle Araguaia River, an anabranching system of central Brazil

    NASA Astrophysics Data System (ADS)

    Lininger, K. B.; Latrubesse, E. M.; Bayer, M.

    2012-12-01

    The Araguaia River is the largest river that drains the Cerrado, or savanna ecosystem, in central Brazil. With a drainage area of about 377,000 km2 and a mean annual discharge of 6,420 m3s-1, the Araguaia River is an anabranching system with a tendency to braid. The study area is a middle section of the river, which maintains a well-developed alluvial floodplain. We use a water budget approach to analyze discharge data from 1976-2006 from four gauging stations along the study area, demonstrating that up to 30% of the river discharge is lost to floodplain storage during flooding periods in some river reaches. We link floodplain storage of discharge to the morphology of the channel and alluvial floodplain, emphasizing the role of morphological features such as paleomeander and oxbow lakes. Floodplain storage also displays a temporal pattern. In addition, we present initial results of floodplain sedimentation rates obtained through Pb-210 geochronology in a reach of the study area near the Aruanã gauging station. Channel and floodplain morphology is linked to floodplain sedimentation patterns. This research contributes to knowledge of water and sediment fluxes between tropical anabranching rivers and their floodplains.

  6. Geomorphic and vegetation processes of the Willamette River floodplain, Oregon: current understanding and unanswered science questions

    USGS Publications Warehouse

    Wallick, J. Rose; Jones, Krista L.; O'Connor, Jim E.; Keith, Mackenzie K.; Hulse, David; Gregory, Stanley V.

    2013-01-01

    This report summarizes the current understanding of floodplain processes and landforms for the Willamette River and its major tributaries. The area of focus encompasses the main stem Willamette River above Newberg and the portions of the Coast Fork Willamette, Middle Fork Willamette, McKenzie, and North, South and main stem Santiam Rivers downstream of U.S. Army Corps of Engineers dams. These reaches constitute a large portion of the alluvial, salmon-bearing rivers in the Willamette Basin. The geomorphic, or historical, floodplain of these rivers has two zones - the active channel where coarse sediment is mobilized and transported during annual flooding and overbank areas where fine sediment is deposited during higher magnitude floods. Historically, characteristics of the rivers and geomorphic floodplain (including longitudinal patterns in channel complexity and the abundance of side channels, islands and gravel bars) were controlled by the interactions between floods and the transport of coarse sediment and large wood. Local channel responses to these interactions were then shaped by geologic features like bedrock outcrops and variations in channel slope. Over the last 150 years, floods and the transport of coarse sediment and large wood have been substantially reduced in the basin. With dam regulation, nearly all peak flows are now confined to the main channels. Large floods (greater than 10-year recurrence interval prior to basinwide flow regulation) have been largely eliminated. Also, the magnitude and frequency of small floods (events that formerly recurred every 2–10 years) have decreased substantially. The large dams trap an estimated 50–60 percent of bed-material sediment—the building block of active channel habitats—that historically entered the Willamette River. They also trap more than 80 percent of the estimated bed material in the lower South Santiam River and Middle and Coast Forks of the Willamette River. Downstream, revetments further

  7. Insights into geomorphic and vegetation spatial patterns within dynamic river floodplains using soft classification approaches

    NASA Astrophysics Data System (ADS)

    Guneralp, I.; Filippi, A. M.; Guneralp, B.; You, M.

    2014-12-01

    Lowland rivers in broad alluvial floodplains create one of the most dynamic landscapes, governed by multiple, and commonly nonlinear, interactions among geomorphic, hydrologic, and ecologic processes. Fluvial landforms and land-cover patches composing the floodplains of lowland rivers vary in their shapes and sizes because of variations in vegetation biomass, topography, and soil composition (e.g., of abandoned meanders versus accreting bars) across space. Such floodplain heterogeneity, in turn, influences future river-channel evolution by creating variability in channel-migration rates. In this study, using Landsat 5 Thematic Mapper data and alternative image-classification approaches, we investigate geomorphic and vegetation spatial patterns in a dynamic large tropical river. Specifically, we examine the spatial relations between river-channel planform and fluvial-landform and land-cover patterns across the floodplain. We classify the images using both hard and soft classification algorithms. We characterize the structure of geomorphic landform and vegetation components of the floodplain by computing a range of class-level landscape metrics based on the classified images. Results indicate that comparable classification accuracies are accrued for the inherently hard and (hardened) soft classification images, ranging from 89.8% to 91.8% overall accuracy. However, soft classification images provide unique information regarding spatially-varying similarities and differences in water-column properties of oxbow lakes and the main river channel. Proximity analyses, where buffer zones along the river with distances corresponding to 5, 10, and 20 river-channel widths are constructed, reveal that the average size of forest patches first increase away from the river banks but they become sparse after a distance of 10 channel widths away from the river.

  8. Numerical investigation of long-term planform dynamics and stability of river meandering on fluvial floodplains

    NASA Astrophysics Data System (ADS)

    Xu, Dong; Bai, Yuchuan; Ma, Jianmin; Tan, Yan

    2011-09-01

    A mathematical model for river meandering and floodplain development is presented under the assumption of constant channel width, which combined Johanneson and Parker (1989) linear theory for flows in river bends and a conceptual depositional model from Howard (1992). A new bank erosion model is also developed, which takes into consideration of the nonlinearity in near-bank velocity and the outer bank height. Simulations reproduce the long-term behavior of river meandering and floodplain evolution in a way very similar to their natural processes. Based on the simulation results, stability of river meandering dynamics is discussed and the concept of filtration effect is introduced to highlight meandering rivers' capability to filter out arbitrarily applied planform disturbance. Simulations are also carried out to investigate the influence of the velocity nonlinearity and the outer bank height in bank erosion model, as well as their combinations. Results show that the consideration of velocity nonlinearity in bank erosion model leads to highly upstream-skewing geometry of fully developed river meanders, as well as a slower downstream migration of meander trains. The influence of nonlinearity in bank erosion model is much smaller than the influence of bank height, which reduces the bank migration rate exponentially in the newly introduced bank erosion model. The outer bank height consideration tends to decelerate the downstream migration rate of river meanders and accelerate lateral expansion of the floodplain as well. Consequently, a broader floodplain is generated compared with simulations without bank height considerations.

  9. Diffusive modeling of global river and floodplain dynamics based on 1km-resolution DEM

    NASA Astrophysics Data System (ADS)

    Yamazaki, D.; Kanae, S.; Oki, T.

    2009-12-01

    Terrestrial water circulation is important both as a component of the climate system and as a freshwater supplying system for human beings. Recent advances in remote sensing have achieved global-scale observation of surface water storage and movement from satellites (e.g. inundated area extent by microwave imagers, terrestrial water storage by GRACE, water surface altitude and river discharge possibly by SWOT). On the other hand, global river routing models, which are practically the only available tool for simulating terrestrial water circulation, have not adequately represented the physical mechanism of terrestrial water storage and movement, such as floodplain inundation dynamics regulated by much smaller-scale topography than global model resolution. A newly developed global river routing model named “Catchment-based Macro-scale Floodplain model” (CaMa-Flood) overcomes this drawback by detailed representation of sub-grid-scale topography (ex. river channel cross-section, catchment boundaries, and floodplain elevation profile). These sub-grid features regulating surface water dynamics are objectively parameterized based on 1km-resolution global DEM and flow direction map. This approach enables explicit prediction of surface water altitude, which is essential for diffusive wave modeling of floodplain inundation dynamics. Thus, CaMa-Flood is expected to simulate not only realistic river discharge but also water depth, inundated area extent, and surface water storage. Improvements from previous global river routing models achieved by CaMa-Flood are summarized as follows: (1) objective parameterization of sub-grid topographies using 1km-resolution datasets, (2) explicit representation of floodplain inundation dynamics, (3) diffusive wave modeling for flow computation instead of kinematic wave modeling, and (4) two dimensional expression of inundated area extent which can be validated against satellite observations. Ability of CaMa-Flood is tested by comparing

  10. Trapping of sediment along the Amazon tidal river in diverse floodplain environments

    NASA Astrophysics Data System (ADS)

    Fricke, A. T.; Nittrouer, C. A.; Ogston, A. S.; Nowacki, D. J.; Souza Filho, P. W.; Silveira, O.; Asp, N. E.

    2013-12-01

    The Amazon tidal river, the freshwater reach that is influenced by tides, extends roughly 800 kilometers upstream of the river mouth. Previous studies suggest that up to one third of the sediment measured at the upstream limit of tides does not reach the ocean, and is likely trapped along the tidal river. Here we present data from a variety of depositional environments along this reach, including intertidal vegetated floodplains, floodplain lakes, and drowned tributary confluences. Sediment delivery to each of these environments is temporally variable as a result of changing tides and river stage, and spatially variable along the continuum from the purely fluvial upstream condition to the strongly tidal downstream environment. Short-term instrument records and direct observations are paired with sedimentological and radiochemical techniques to identify mechanisms of sediment exchange between river and floodplain and associated patterns of sediment accumulation. Sediments in vegetated intertidal floodplains exhibit tidal laminations and incised channel networks similar to muddy marine intertidal areas. Floodplain lakes experience dramatic seasonal changes in size, and during high flows of the river skim water and sediment from the Amazon River by providing a shortcut relative to the meandering mainstem. Amazon sediment is fluxed into the drowned tributary confluences (rías) of the Xingu and Tapajos Rivers by density-driven underflows. In the Tapajos Ría, sediment from the Amazon River has built a 25-km long birdfoot delta, suggesting these tributaries may be net sinks of sediment, rather than sources. These findings help define the importance of each tidal environment in trapping Amazon sediment before it reaches the marine environment.

  11. Multiple effects of hydrological connectivity on floodplain processes in human modified river systems

    NASA Astrophysics Data System (ADS)

    Hein, Thomas; Bondar-Kunze, Elisabeth; Preiner, Stefan; Reckendorfer, Walter; Tritthart, Michael; Weigelhofer, Gabriele; Welti, Nina

    2014-05-01

    Floodplain and riparian ecosystems provide multiple functions and services of importance for human well-being and are of strategic importance for different sectors at catchment scale. Especially floodplains in the vicinity of urban areas can be areas of conflicting interests ranging from different land use types, flood water retention, drinking water production and recreation to conservation of last remnants of former riverine landscape, as it is the case in floodplains in the Danube Nationalpark downstream Vienna. Many of these ecosystem functions and services are controlled by the exchange conditions between river main channel and floodplain systems, the hydrological connectivity. At the same time these systems have been highly altered and especially the connectivity has been severely impaired. Thus, far ranging effects of changes in hydrological connectivity at various levels can be expected in altered floodplain systems. The aim of this presentation is to explore the complex control of different ecosystem functions and associated services by different parameters of hydrological connectivity, ranging from nutrient, sediment and matter dynamics and biodiversity aspects. Increasing connectivity will be shown to impact microbial dynamics, sediment-water interactions, carbon dynamics and trophic conditions, thus affecting the fundamental functions of particular floodplain systems at various spatial and temporal scales. Based on these changes also the provision of ecosystem services of floodplains is affected. The results clearly show that hydrological connectivity needs to be considered in a sustainable management approach.

  12. A comparison of sediment deposition in two adjacent floodplains of the River Adour in southwest France.

    PubMed

    Brunet, R-C; Brian Astin, K

    2008-09-01

    Two floodplains within the catchment of the River Adour (SW France) have been examined in order to analyse spatio-temporal variations in discharge and suspended matter flux. Both floodplain zones were found to be excellent sites for the interception of suspended sediment. The narrow riparian vegetative strips (RVS) within each zone were found to retain 92-98% of the sediment trapped within the floodplain during each of three separate flood events. The precise level of sediment deposited within the floodplain was found to be dependent on micro-topographical features and the nature of the vegetation: the wooded areas within the RVS being particularly effective at trapping sediment. Mean masses of sediment collected in the flood plains ranged from 75 kg m(-2) in the RVS to 0.02 kg m(-2) in the areas of the floodplain inundated by back-up flows. Using data on discharge and sediment fluxes within the catchment gathered over a period of 25 years it is possible to discern how hydroclimatic fluctuations have affected the watershed with periods of sediment retention within the floodplain zones alternating with periods of sediment export. Anthropogenic activity, involving river management, including the cutting of meanders, the construction of dykes for flood prevention and the use of water for agricultural purposes, has also had a major impact during this period, particularly in the downstream areas of the catchment.

  13. The impact of nitrogen contamination and river modification on a Mississippi River floodplain lake.

    PubMed

    Karthic, Indu; Brugam, Richard B; Retzlaff, William; Johnson, Kevin

    2013-10-01

    Anthropogenic nitrogen contamination has increased in ecosystems around the world (frequently termed the "nitrogen cascade"). Coke production for steel manufacturing is often overlooked as a source of nitrogen to natural ecosystems. We examined sediment cores from a Horseshoe Lake, a floodplain lake located just East of St. Louis Missouri (USA) to test whether a coking plant effluent could be traced using stable isotopes of nitrogen and diatom microfossils. The distribution of δ(15)N values in surface sediment samples from the lake shows the highest values near the coking plant effluent. Stable isotopes of nitrogen from 4 sediment cores using a mixing model showed three sources of nitrogen since 1688 CE. The first source (active between 1688 and 1920 CE) had a calculated δ(15)N value ranging between -0.4 and 1.1‰ depending on the core. After 1920 a second source with a δ(15)N ranging between 10.6 and 15.4‰ became active. The change in these sources coincides with the construction of a coking plant on the lake shore. A third source with a value approximately 7.0‰ was present at all times and represents background. The diatom microfossil assemblages present from 1688 CE to the late 1800s are dominated by the planktonic species Aulacoseira granulata and periphytic and benthic genera Gomphonema, Cocconeis, and Lyrella. After the late 1800s the diatom assemblages are dominated by Staurosira species indicating a shift of species from high flow riverine environments to epipelic species from a lake environment. Diatom microfossils seem to track the reduction in flooding due to leveeing of the floodplain and the isolation of the lake from the river. Our results show how stable isotopes of nitrogen can be used to track nitrogen inputs from industrial sources. Diatom changes corresponded with changes in connectivity between the Mississippi River and its floodplain. PMID:23851349

  14. Evaluating the effectiveness of floodplain restoration on the North Fork John Day River, Northeast Oregon, USA

    NASA Astrophysics Data System (ADS)

    Clifton, C. F.; Blanton, P.; Long, W.; Walterman, M. T.; McDowell, P. F.; Maus, P.

    2007-12-01

    Over the last decade hundreds of river restoration projects intended to maintain, protect, and restore watersheds, rivers, and habitat for native species in the Pacific Northwest have been implemented. By some counts, investment in watershed restoration exceeds hundreds of millions of dollars annually yet the effectiveness of these efforts remains an elusive question (Roni, 2005). Remote sensing and GIS technologies show great promise for large-scale river monitoring, however most natural resource organizations who implement these projects have limited budget and staff and would benefit from simple, low cost monitoring techniques that use readily available imagery. We used 1:24000 digitized orthorectified resource imagery from 1995, and National Agriculture Imagery Program (NAIP) digital orthophotography from 2005 to assess the effectiveness of floodplain restoration on a 16 km reach of the North Fork John Day River. Between 1993 and 1997 this section was restored by mechanically removing, reshaping, and revegetating cobble-boulder tailings piles left from dredge mining. The project was intended to directly improve floodplain function (i.e. inundation, riparian habitat) and indirectly improve instream habitat (pools, spawning) by reconnecting the active river channel with a reconstructed floodplain surface. Project effectiveness was not well documented initially in terms of quantifying floodplain functional area improvement or channel condition and response at the river-reach scale. Our objectives were to field-verify remote sensing measurements of response variables to test the applicability of available remote sensing imagery for project effectiveness monitoring, and to quantify adjustment in river response variables, using a "before-after" case study approach. Bracketing restoration activities with 1995 and 2000 imagery, we developed and tested methods for acquisition and processing of digital imagery and identified a core set of response variables to sample

  15. Archaeological sedimentology of overbank silt deposits on the floodplain of the Ohio river near Louisville, Kentucky

    USGS Publications Warehouse

    Gray, H.H.

    1984-01-01

    The surface of the floodplain of the Ohio River about 20km southwest of Louisville, Kentucky, is a series of linear ridges and swales that are subparallel to the channel of the river, which here is relatively straight and flows southward. Numerous prehistoric occupational sites are located on these ridges. The sediments that underlie the ridges, which were examined in four archaeological excavations as deep as 8 m, are predominantly sandy silt and silty fine to very fine sand and appear to be mainly the product of overbank deposition from suspended load. Abundant cultural material and occupational sites dating as early as 10,000 years BP are found in the sediments at depths as great as 6??5 m. The fine sediments of the floodplain are underlain by sand and gravel. The context of the cultural materials and the stratigraphy and morphology of the deposits indicate that the ridged deposits began as linear riverside sand and gravel bars. These were succeeded upward by fine-grained overbank deposits in which the ridged morphology was maintained because the overbank silt and fine sand were deposited as prograding elongate bars at high water. As the floodplain ridge built upward, the sedimentation rate decreased and the sand content of the sediments diminished, and as the river channel occasionally shifted, the ridged deposits were built in successive subparallel sequences. Two archaeological consequences are implicit in this depositional model of orderly growth of the floodplain. First, available archaeological data from floodplain segments along other parts of the river should confirm the model; and second, the model should make it possible to search the floodplains of the Ohio River for stratified sites of any desired age. ?? 1984.

  16. A numerical investigation of the impacts of river and floodplain restoration on the process of floodwave attenuation

    NASA Astrophysics Data System (ADS)

    Stone, M. C.; Byrne, C.; Morrison, R.

    2015-12-01

    It is widely recognized that past river engineering, flood control, and floodplain development activities have tended to work against nature rather than with it. The consequence in many cases has been severe degradation of our natural ecosystems. This, combined with an increased appreciation for the benefits of properly functioning ecosystems, has prompted efforts to restore rivers to a more natural state. However, most restoration projects currently focus on a narrow set of goals, such as endangered species recovery or channel stabilization. In order to shift the restoration community towards more holistic perspectives and approaches, it is necessary to improve understanding of river and floodplain hydrogeomorphic processes and their role in supporting healthy ecosystems. The goal of this research was to investigate the impacts of river engineering and restoration practices on the process of floodwave attenuation. This goal was addressed through numerical investigations that allowed us to: (1) quantify mass and momentum fluxes between river channels and floodplains; (2) investigate the influence of mass and momentum fluxes on floodwave attenuation processes; and (3) evaluate the impacts of river and floodplain restoration on floodwave attenuation. Two-dimensional hydrodynamic models were applied to the Rio Grande, San Joaquin, and Gila rivers in the Southwestern United States using novel modeling approaches to describe dynamic floodplain roughness, fluxes at channel/floodplain interfaces, and attenuation along river corridors. The results provide important insights into the role of floodplain characteristics on floodwave movement and the potential for enhancing floodwave attenuation through river restoration.

  17. Fates of pollutants from uranium mining in floodplain of a meandering river (the Ploucnice, Czech Republic)

    NASA Astrophysics Data System (ADS)

    Matys Grygar, Tomas; Elznicova, Jitka; Majerova, Lucie; Babek, Ondrej; Kiss, Timea; Havelcova, Martina; Hosek, Michal

    2014-05-01

    The Ploucnice River (Czech Republic) received two groups of element pollutants. The first was Pb-Cu-Sb-Zn association with the onset early in 20th century; we attribute it to diffuse pollution at levels of the river watershed and/or mid European region with both atmospheric and fluvial transports. The second group was U-Zn-Ni-Co-Ba association related to uranium mining and mine-water processing during the 1970s and 1980s. Pollution hence allowed for identifying two chemostratigraphic units in 20th century floodplain fill, whose lower boundaries we interpret as isochronous at a given river reach. Historical and current maps and aerial photographs and current aerial lidar scanning allowed reconstructing the floodplain development. Electrical resistivity tomography (ERT) produced insight into the floodplain architecture. Three geomorphic levels were identified in the studied river reach: active floodplain, abandoned floodplain (paleochannels there are now inundated at >Q50), and pre-Holocene or early Holocene terrace. Each level has its own pattern of pollution by Pb, U and polyaromatic hydrocarbons. The terrace and abandoned floodplain sediments together with deeper sediments from active floodplain allowed construction of background functions for pre-industrial concentrations of target elements and subsequent calculation of enrichment factors. That approach corrects for grain-size effects and thus coarser unsorted terrace sediments, finer silty sands of the abandoned floodplain, and the finest muds of the active floodplain were jointly processed. Such data processing was a pre-requisite for evaluation of weak diffuse pollution from early 20th century and recognition of post-depositional changes in pollutant concentrations. The main portion of pollutants related to uranium mining got into the river system in 1970s with peak in 1981 during a summer flood with >Q50 discharge. The pollution impacted the entire river system (enhanced Ra-226 activities were detected at

  18. Hyporheic flow patterns in relation to large river floodplain attributes Journal

    EPA Science Inventory

    Field-calibrated models of hyporheic flow have emphasized low-order headwater systems. In many cases, however, hyporheic flow in large lowland river floodplains may be an important contributor to ecosystem services such as maintenance of water quality and habitat. In this study, ...

  19. A PROBABILITY SURVEY OF SUCCESSIONAL FOREST COMPOSITION AND CONDITION IN A GREAT RIVER FLOODPLAIN LANDSCAPE

    EPA Science Inventory

    Floodplains within the Great River Ecosystems (GREs) of the central U.S. are composed of dynamic mosaics of successional habitat that (when unmodified) are typically dominated by cottonwood forest (Populus ssp.). GRE riparian habitat condition and successional dynamics are linked...

  20. Spatial variability in floodplain resistance to erosion on a large meandering, mixed bedrock-alluvial river

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatial heterogeneities of the erosion-resistance properties of the channel banks and floodplains, such as grain size characteristics and the presence of vegetation and bedrock, can have a substantial influence on river morphodynamics, resulting in complex planform geometries and highly variable rat...

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

    EPA Science Inventory

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

  2. A spatial simulation model for forest succession in the Upper Mississippi River floodplain

    USGS Publications Warehouse

    Yin, Y.; Wu, Y.; Bartell, S.M.

    2009-01-01

    A Markov-chain transition model (FORSUM) and Monte Carlo simulations were used to simulate the succession patterns and predict a long-term impact of flood on the forest structure and growth in the floodplain of the Upper Mississippi River and Illinois River. Model variables, probabilities, functions, and parameters were derived from the analysis of two comprehensive field surveys conducted in this floodplain. This modeling approach describes the establishment, growth, competition, and death of individual trees for modeled species on a 10,000-ha landscape with spatial resolution of 1 ha. The succession characteristics of each Monte Carlo simulation are summed up to describe forest development and dynamics on a landscape level. FORSUM simulated the impacts of flood intensity and frequency on species composition and dynamics in the Upper Mississippi River floodplain ecosystem. The model provides a useful tool for testing hypotheses about forest succession and enables ecologists and managers to evaluate the impacts of flood disturbances and ecosystem restoration on forest succession. The simulation results suggest that the Markov-chain Monte Carlo method is an efficient tool to help organize the existing data and knowledge of forest succession into a system of quantitative predictions for the Upper Mississippi River floodplain ecosystem. ?? 2009 Elsevier B.V.

  3. Managing floodplain-forest restoration in European river landscapes combining ecological and flood-protection issues.

    PubMed

    Leyer, Ilona; Mosner, Eva; Lehmann, Boris

    2012-01-01

    Throughout Europe the demands for improved flood protection on the one hand and the requirements to maintain and enhance floodplain forests on the other are perceived as conflicting goals in river-basin management, revealing the urgent need for strategies to combine both issues. We developed an interdisciplinary approach for floodplain-forest restoration identifying sites suitable for reforestations from both an ecological and hydraulic point of view. In the ecological module, habitat-distribution models are developed providing information on ecologically suitable sites. In the hydraulic module, a two-dimensional hydrodynamic-numerical model (2D-HN model) delivers the requested hydraulic information. The output of the two models is intersected. Subsequently, in an iterative procedure, the potential of plantings without exceeding critical water levels can be identified by hydraulic evaluation using the 2D-HN-model. The approach is exemplified using two reforestation scenarios at the Elbe River, Germany, showing considerable potential for softwood forest establishment without negative hydraulic effects. The approach reported here provides a solution for a severe conflict in river-basin management that hampers the reestablishment of the strongly threatened floodplain forests in Europe. Alternative measures to enhance floodplain-forest regeneration feasible under certain preconditions are discussed in the context of the current state of European large rivers.

  4. River-floodplain exchange and its effects on the fluvial oxygen regime in a large tropical river system (Kafue Flats, Zambia)

    NASA Astrophysics Data System (ADS)

    Zurbrügg, Roland; Wamulume, Jason; Kamanga, Romas; Wehrli, Bernhard; Senn, David B.

    2012-09-01

    Hydrological exchange between a river and its floodplain plays a critical role in maintaining key ecosystem services like habitat formation, nutrient transformation, and flood attenuation. We studied the spatial and temporal patterns of river-floodplain exchange in the Kafue Flats, a 6500-km2, dam-impacted floodplain ecosystem in Zambia. In addition, we characterized the effects of floodplain runoff on river biogeochemistry and assessed dam-related changes in the hydrological regime. The basic flood pulse concept poorly describes conditions in the Kafue Flats. Instead, high resolution measurements of discharge and tracers (specific conductivity,δ18O-H2O) along 410 km of river revealed substantial spatial variations in both the magnitude and direction of river-floodplain exchange. During peak discharge, a river channel constriction, 230 km into the floodplain, diverted as much as 80% of the river's ˜700 m3 s-1discharge into the floodplain. As a net result, >80% of the water exiting the Kafue Flats via the river, either passed through the floodplain or originated from precipitation on the floodplain. This floodplain-derived water had a strong impact on river water quality, resulting in a seasonally recurring sharp decline in dissolved oxygen levels to <50μM that persisted for 150 km downstream. A comparison with historical flow data showed that concurrent bank overflow and floodplain inflows were a sustained pattern during the wet season. However, lateral exchange over an annual cycle has been reduced by as much as 50% due to dam operation.

  5. Impact of a changed inundation regime caused by climate change and floodplain rehabilitation on population viability of earthworms in a lower River Rhine floodplain.

    PubMed

    Thonon, Ivo; Klok, Chris

    2007-01-01

    River floodplains are dynamic and fertile ecosystems where soil invertebrates such as earthworms can reach high population densities. Earthworms are an important food source for a wide range of organisms including species under conservation such as badgers. Flooding, however, reduces earthworm numbers. Populations recover from cocoons that survive floods. If the period between two floods is too short such that cocoons cannot develop into reproductive adults, populations cannot sustain themselves. Both climate change and floodplain rehabilitation change the flooding frequency affecting earthworm populations. The present paper estimates the influence of climate change and floodplain rehabilitation on the viability of earthworm populations in a Dutch floodplain; the Afferdensche and Deestsche Waarden along the River Waal. This floodplain will be part of major river rehabilitation plans of the Dutch government. In those plans, the floodplain will experience the construction of a secondary channel and the removal of part of its minor embankment. To estimate the impact of these plans and climate change, we used a dataset of daily discharges for 1900-2003 for the River Rhine at the Dutch-German border. We perturbed this dataset to obtain two new datasets under climate change scenarios for 2050 and 2100. From the original and two projected datasets we derived the frequency distributions for the annual periods without inundations for the studied floodplain. We subsequently compared the duration of these inundation-free (dry) periods with the maturation age distribution for L. rubellus as derived from a Dynamic Energy Budget model. This comparison yielded in which parts of our study area and under which climate conditions the populations would still be viable, be able to adapt or become extinct. The results show that climate change has almost no adverse effect on earthworm viability. This is because climate change reduces the flooding frequency during the earthworms growing

  6. Impact of a changed inundation regime caused by climate change and floodplain rehabilitation on population viability of earthworms in a lower River Rhine floodplain.

    PubMed

    Thonon, Ivo; Klok, Chris

    2007-01-01

    River floodplains are dynamic and fertile ecosystems where soil invertebrates such as earthworms can reach high population densities. Earthworms are an important food source for a wide range of organisms including species under conservation such as badgers. Flooding, however, reduces earthworm numbers. Populations recover from cocoons that survive floods. If the period between two floods is too short such that cocoons cannot develop into reproductive adults, populations cannot sustain themselves. Both climate change and floodplain rehabilitation change the flooding frequency affecting earthworm populations. The present paper estimates the influence of climate change and floodplain rehabilitation on the viability of earthworm populations in a Dutch floodplain; the Afferdensche and Deestsche Waarden along the River Waal. This floodplain will be part of major river rehabilitation plans of the Dutch government. In those plans, the floodplain will experience the construction of a secondary channel and the removal of part of its minor embankment. To estimate the impact of these plans and climate change, we used a dataset of daily discharges for 1900-2003 for the River Rhine at the Dutch-German border. We perturbed this dataset to obtain two new datasets under climate change scenarios for 2050 and 2100. From the original and two projected datasets we derived the frequency distributions for the annual periods without inundations for the studied floodplain. We subsequently compared the duration of these inundation-free (dry) periods with the maturation age distribution for L. rubellus as derived from a Dynamic Energy Budget model. This comparison yielded in which parts of our study area and under which climate conditions the populations would still be viable, be able to adapt or become extinct. The results show that climate change has almost no adverse effect on earthworm viability. This is because climate change reduces the flooding frequency during the earthworms growing

  7. Deposition and fate of organic carbon in floodplains along a tropical semiarid lowland river (Tana River, Kenya)

    NASA Astrophysics Data System (ADS)

    Omengo, Fred O.; Geeraert, Naomi; Bouillon, Steven; Govers, Gerard

    2016-04-01

    Inland waters organic carbon (OC) burial by sedimentation has recently been shown to be an important component in river catchment carbon (C) budgets. However, data on OC burial by sedimentation are hitherto largely limited to temperate zones. We investigated the deposition and fate of sediment-associated OC in the floodplains of the tropical lowland Tana River (Kenya), between two main gaging stations (Garissa and Garsen). Freshly deposited surface sediments and sediment cores were sampled and analyzed for OC, total nitrogen content, stable isotope signatures (δ13C) of OC, and grain size distribution. In addition, we incubated sediment cores to quantify CO2 production as a proxy for OC mineralization. While the floodplain receives sediment with a relatively low OC content (1.56 ± 0.42%), sediments are enriched with OC inputs from floodplain vegetation to levels above 3%. Sediment cores show a sharp decrease of OC with depth, from 3 to 12% OC in the (sub) surface to less than 1% OC below approximately 60 cm depth. Relatively elevated OC mineralization rates (0.14 ± 0.07 mol. CO2 kgC-1 d-1) were recorded. We used these data to make a first assessment of the C burial efficiency of the Tana River floodplain. In contrast to what is observed in temperate environments, over 50% of C present in the top layers is lost in less than a century. While significant amounts of OC are buried in the Tana River floodplain, the high rates of postdepositional loss limit the development of a long-term C sink within this tropical floodplain.

  8. Transportation infrastructure, river confinement, and impacts on floodplain and channel habitat, Yakima and Chehalis rivers, Washington, U.S.A.

    NASA Astrophysics Data System (ADS)

    Blanton, Paul; Marcus, W. Andrew

    2013-05-01

    Although floodplain roads and railroads are recognized as confining features with potentially large environmental impacts, few studies have explored the linkages between these structures and the natural disturbance regime that creates and maintains channel and riparian habitat. This study compares paired floodplain reaches with or without transportation infrastructure confining the riparian zone along the Yakima and Chehalis rivers in Washington State. Channel and floodplain habitat were degraded in the artificially confined reaches. Confined channels were narrower, simpler in planform, and relatively devoid of depositional surfaces such as bars and islands. Floodplains adjacent to confined channels exhibited degraded riparian forest and less refugium habitat such as side channels, ponds, and alcoves important for endangered salmonids and other biota. The results support hypotheses about how human modification of the floodplain landscape disrupts the flow regime and connectivity along riparian corridors. Neither simple buffer zones nor metrics such as valley width index adequately capture the disturbance-based landscape processes that drive riparian and channel habitat integrity. Future studies and indices of valley confinement, a critical driver of fluvial geomorphic processes, need to pay closer attention to artificial confinement of the channel, the riparian zone, and the active floodplain surfaces in order to portray the true constraints on fluvial processes.

  9. Floodplain disconnection, changes in river corridor complexity, and implications for river restoration along lower Deer Creek, Tehama County, CA

    NASA Astrophysics Data System (ADS)

    Kondolf, G. M.; Tompkins, M. R.

    2008-12-01

    River channels and floodplains are inextricably linked elements of river ecosystems, and hydrologic inter- connections sustain geomorphic and ecological values. Many river channels and floodplains have been disconnected in California, prompting river managers to consider floodplain reconnection to restore degraded waterways. Deer Creek, a 600 km2 tributary to the Sacramento River still supports reproduction of native spring-run Chinook salmon in its upper reaches. However, its lower, alluvial reaches were channelized, cleared, and partially leveed by a 1949 US Army Corps of Engineers flood control project. The catchment of Deer Creek is largely undisturbed, so its flow regime and sediment load are largely unimpaired. Thus the potential exists to restore lower Deer Creek to something like its complex, ecologically-productive pre-disturbance conditions if artificial constraints are removed, and thus levee setbacks have been proposed for Deer Creek to reduce concentration of flows in the main channel and allow the main channel to become more hydraulically rough with vegetation and gravel bars. We made detailed measurements of pre- disturbance channel conditions from 1938 aerial photographs and compared those measurements with recent aerial photographs to document the project-induced changes. We measured decreases in riffle habitat (up to 84%), pool habitat (up to 100%), cumulative channel length (up to 72%), shaded riverine aquatic habitat (up to 81%) and riparian vegetation (up to 94%), and increases in riffle spacing (up to 1162%), pool spacing (up to 178%), and low flow channel width (up to 84%) between 1938 and 1999. These results suggest that significant and persistent reductions in river corridor complexity can be associated with floodplain disconnection, and provide an estimate of restoration potential for floodplain reconnection on lower Deer Creek.

  10. [The role of the floodplain gradient in structuring of testate amoebae communities in the Ilych River].

    PubMed

    Mazeĭ, Iu A; Malysheva, E A; Lapteva, E M; Komarov, A A; Taskaeva, A A

    2012-01-01

    Forty-two testate amoebae taxa were identified in alluvial soils of floodplain islands in the Ilych River. Among the pedo- and eurybionts, there were aquatic rhizopods. Along the floodplain transect (willow --> meadow --> deciduous forest --> coniferous forest), the testate amoebae community changed directly. There are spatially homogeneous (low beta-diversity) testacean communities but species rich on the local level (high alpha-diversity) within forests. Within willows and meadows, communities are characterized by low alpha-diversity and high heterogeneity that leads to high gamma-diversity. PMID:22988761

  11. [The role of the floodplain gradient in structuring of testate amoebae communities in the Ilych River].

    PubMed

    Mazeĭ, Iu A; Malysheva, E A; Lapteva, E M; Komarov, A A; Taskaeva, A A

    2012-01-01

    Forty-two testate amoebae taxa were identified in alluvial soils of floodplain islands in the Ilych River. Among the pedo- and eurybionts, there were aquatic rhizopods. Along the floodplain transect (willow --> meadow --> deciduous forest --> coniferous forest), the testate amoebae community changed directly. There are spatially homogeneous (low beta-diversity) testacean communities but species rich on the local level (high alpha-diversity) within forests. Within willows and meadows, communities are characterized by low alpha-diversity and high heterogeneity that leads to high gamma-diversity.

  12. Nutrient dynamics in the lower Mississippi river floodplain: Comparing present and historic hydrologic conditions

    USGS Publications Warehouse

    Schramm, H.L.; Cox, M.S.; Tietjen, T.E.; Ezell, A.W.

    2009-01-01

    Alterations to the lower Mississippi River-floodplain ecosystem to facilitate commercial navigation and to reduce flooding of agricultural lands and communities in the historic floodplain have changed the hydrologic regime. As a result, the flood pulse usually has a lower water level, is of shorter duration, has colder water temperatures, and a smaller area of floodplain is inundated. Using average hydrologic conditions and water temperatures, we used established nitrogen and phosphorus processes in soils, an aquatic ecosystem model, and fish bioenergetic models to provide approximations of nitrogen and phosphorus flux in Mississippi River flood waters for the present conditions of a 2-month (mid-March to mid-May) flood pulse and for a 3-month (mid-March to mid-June), historic flood pulse. We estimated that the soils and aquatic biota can remove or sequester 542 and 976 kg nitrogen ha-1 during the present and historic hydrologic conditions, respectively. Phosphorus, on the other hand, will be added to the water largely as a result of anaerobic soil conditions but moderated by biological uptake by aquatic biota during both present and historic hydrologic conditions. The floodplain and associated water bodies may provide an important management opportunity for reducing downstream transport of nitrogen in Mississippi River waters. ?? 2009, The Society of Wetland Scientists.

  13. The effect of channelization on floodplain sediment deposition and subsidence along the Pocomoke River, Maryland

    USGS Publications Warehouse

    Kroes, D.E.; Hupp, C.R.

    2010-01-01

    The nontidal Pocomoke River was intensively ditched and channelized by the mid-1900s. In response to channelization; channel incision, head-cut erosion, and spoil bank perforation have occurred in this previously nonalluvial system. Six sites were selected for study of floodplain sediment dynamics in relation to channel condition. Short- and long-term sediment deposition/subsidence rates and composition were determined. Short-term rates (four years) ranged from 0.6 to 3.6 mm/year. Long-term rates (15-100+ years) ranged from -11.9 to 1.7 mm/year. 137Cs rates (43 years) indicate rates of 0.24 to 7.4 mm/year depending on channel condition. Channelization has limited contact between streamflow and the floodplain, resulting in little or no sediment retention in channelized reaches. Along unchannelized reaches, extended contact and depth of river water on the floodplain resulted in high deposition rates. Drainage of floodplains exposed organic sediments to oxygen resulting in subsidence and releasing stored carbon. Channelization increased sediment deposition in downstream reaches relative to the presettlement system. The sediment storage function of this river has been dramatically altered by channelization. Results indicate that perforation of spoil banks along channelized reaches may help to alleviate some of these issues. ?? 2010 American Water Resources Association. No claim to original U.S. government works.

  14. Supplemental water releases for fisheries restoration in a Brazilian floodplain River: A conceptual model

    USGS Publications Warehouse

    Godinho, Alexandre L.; Kynard, B.; Martinez, C.B.

    2007-01-01

    Highly productive floodplain rivers in Brazil and elsewhere provide livelihood and recreational fishing for millions of people around the world, but damming and controlled water discharge are a threat to these valuable ecosystems. Supplemental water releases (SWRs) at a dam are increasingly used for restoring fisheries productivity in many floodplain rivers. We proposed a conceptual model for a hypothetical water release to enhance fisheries using Tre??s Marias Reservoir (TMR) on the Sa??o Francisco River (SFR), Brazil. The information needed by the model follows: (i) Biologically, what is the best release date? (ii) How much water will be released? (iii) What is the pattern of impoundment and how much impounded water will be released? (iv) What is the lost revenue to the power plant associated with SWR? (v) What is the relationship between river discharge and the area of floodplain that is flooded? (vi) What is the relationship between SWR and fisheries value? Ichthyoplankton studies in the SFR showed a clear positive relationship between fish density and water level (WL). While the relationship between WL and floodplain area flooded and recruitment is not known, we concluded the best date for release is when there is a natural flood, which naturally triggers fish spawning and the SWR will add to the natural flood and cover a greater floodplain area. The released volume will range from 0.302km3 to 2.192 km3, depending on SWR duration. In most years from 1976 to 2003, TMR impounded enough water for SWR only in the second half of the fish-spawning season (January-March). Lost revenue at TMR depended on release volume and ranged from US$ 0.493 million to US$ 3.452 million for the actual power rate. However, SWR could increase commercial fisheries income an estimated US$ 4.468 million. We forecast that SWR can bring fisheries benefits that surpass the lost revenue.

  15. Anatomy and dynamics of a floodplain, Powder River, Montana, U.S.A.

    USGS Publications Warehouse

    Pizzuto, J.E.; Moody, J.A.; Meade, R.H.

    2008-01-01

    Centimeter-scale measurements on several Powder River floodplains provide insights into the nature of overbank depositional processes that created the floodplains; during a 20-year period after a major flood in 1978. Rising stages initially entered across a sill at the downriver end of the floodplains. Later, as stages continued to rise, water entered the floodplains through distinct low saddles along natural levees. The annual maximum depth of water over the levee crest averaged 0.19 in from 1983 through 1996, and the estimated flow velocities were approximately 0.15 m s-1. Water ponded in the floodplain trough, a topographic low between the natural levee and the pre-flood riverbank, and mud settled as thin layers of nearly constant thickness. Mud layers alternated with sand layers, which were relatively thick near the channel. Together, these beds created a distinctive natural levee. In some locations, individual flood deposits began as a thin mud layer that gradually coarsened upwards to medium-grained sand. Coarsening-upwards sequences form initially as mud because only the uppermost layers of water in the channel supply the first overbank flows, which are rich in mud but starved of sand. At successively higher stages, fine sands and then medium sands increase in concentration in the floodwater and are deposited as fine- and medium-sand layers overlying the initial mud layer. Theoretical predictions from mathematical models of sediment transport by advection and diffusion indicate that these processes acting alone are unlikely to create the observed sand layers of nearly uniform thickness that extend across much of the floodplain. We infer that other transport processes, notably bedload transport, must be important along Powder River. Even with the centimeter-scale measurements of floodplain deposits, daily hydraulic data, and precise annual surface topographic surveys, we were unable to determine any clear correspondence between the gauged flow record of

  16. Linking river, floodplain, and vadose zone hydrology to improve restoration of a coastal river affected by saltwater intrusion.

    PubMed

    Kaplan, D; Muñoz-Carpena, R; Wan, Y; Hedgepeth, M; Zheng, F; Roberts, R; Rossmanith, R

    2010-01-01

    Floodplain forests provide unique ecological structure and function, which are often degraded or lost when watershed hydrology is modified. Restoration of damaged ecosystems requires an understanding of surface water, groundwater, and vadose (unsaturated) zone hydrology in the floodplain. Soil moisture and porewater salinity are of particular importance for seed germination and seedling survival in systems affected by saltwater intrusion but are difficult to monitor and often overlooked. This study contributes to the understanding of floodplain hydrology in one of the last bald cypress [Taxodium distichum (L.) Rich.] floodplain swamps in southeast Florida. We investigated soil moisture and porewater salinity dynamics in the floodplain of the Loxahatchee River, where reduced freshwater flow has led to saltwater intrusion and a transition to salt-tolerant, mangrove-dominated communities. Twenty-four dielectric probes measuring soil moisture and porewater salinity every 30 min were installed along two transects-one in an upstream, freshwater location and one in a downstream tidal area. Complemented by surface water, groundwater, and meteorological data, these unique 4-yr datasets quantified the spatial variability and temporal dynamics of vadose zone hydrology. Results showed that soil moisture can be closely predicted based on river stage and topographic elevation (overall Nash-Sutcliffe coefficient of efficiency = 0.83). Porewater salinity rarely exceeded tolerance thresholds (0.3125 S m(-1)) for bald cypress upstream but did so in some downstream areas. This provided an explanation for observed vegetation changes that both surface water and groundwater salinity failed to explain. The results offer a methodological and analytical framework for floodplain monitoring in locations where restoration success depends on vadose zone hydrology and provide relationships for evaluating proposed restoration and management scenarios for the Loxahatchee River.

  17. Plant communities in relation to flooding and soil contamination in a lowland Rhine River floodplain.

    PubMed

    Schipper, Aafke M; Lotterman, Kim; Leuven, Rob S E W; Ragas, Ad M J; de Kroon, Hans; Hendriks, A Jan

    2011-01-01

    Using canonical correspondence analysis (CCA), relationships were investigated between plant species composition and flooding characteristics, heavy metal contamination and soil properties in a lowland floodplain of the Rhine River. Floodplain elevation and yearly average flooding duration turned out to be more important for explaining variation in plant species composition than soil heavy metal contamination. Nevertheless, plant species richness and diversity showed a significant decrease with the level of contamination. As single heavy metal concentrations seemed mostly too low for causing phytotoxic effects in plants, this trend is possibly explained by additive effects of multiple contaminants or by the concomitant influences of contamination and non-chemical stressors like flooding. These results suggest that impacts of soil contamination on plants in floodplains could be larger than expected from mere soil concentrations. In general, these findings emphasize the relevance of analyzing effects of toxic substances in concert with the effects of other relevant stressors.

  18. Hydrodynamic Modeling of Flood Dynamics and Restoration Potential of Lower Missouri River Floodplains

    NASA Astrophysics Data System (ADS)

    Lindner, G. A.

    2012-12-01

    Lower Missouri River floodplains have the potential to provide multiple ecosystem services including agricultural production, floodwater storage, nutrient processing, and provision of habitats. In this research, a 2-dimensional hydrodynamic model of a representative looped floodplain bottom of approximately 20 km is utilized to explore how floodplain inundation contributes to ecosystem benefits and costs. High resolution 2-dimensional hydrodynamic modeling provides insights into the way velocities, flood stages, residence times, and transported constituents (sediment, nutrients, and fish larvae, for example) are affected by levee geometry, floodplain vegetation patterns, and flood magnitude and duration. The utility of 2-dimensional numerical hydraulic models to represent the channel and floodplain are demonstrated at a scale relevant to understanding processes that control channel/floodplain dynamics. The sensitivity of model response to alternative land use scenarios, including levee setbacks and variable overbank roughness, is quantified using hydraulic parameters such as velocity, water level, conveyance, and residence time. The 2-dimensional models are calibrated to existing 1-dimensional modeling solutions and field measurements of water surface from 1993 and 2007 for the 2-year, 5-year, and 10-year recurrence intervals. Calibration runs with current levee configurations are matched to approximately ±0.1 meters. Simulations of alternative land use scenarios demonstrate the tradeoffs between ecological restoration and flood risk reductions. Levee setbacks with low hydraulic roughness associated with traditional row crop agriculture on the floodplains have the greatest potential for flood stage reductions, while native plant communities with higher roughness can negate the effects of the setbacks by increasing water levels due to enhanced frictional resistance. Residence times, which are presumed to be related to ecosystem services, demonstrate increasingly

  19. Floodplain influence on carbon speciation and fluxes from the lower Pearl River, Mississippi

    NASA Astrophysics Data System (ADS)

    Cai, Yihua; Shim, Moo-Joon; Guo, Laodong; Shiller, Alan

    2016-08-01

    To investigate the floodplain influence on carbon speciation and export to the northern Gulf of Mexico, water samples were collected monthly from two sites in the East Pearl River (EPR) basin during 2006-2008. Additionally, four spatial surveys in the river basin between those two sites were also conducted. Compared with the upstream sampling site at Bogalusa, MS, dissolved inorganic carbon (DIC) and particulate organic carbon (POC) concentrations were 36% and 55% lower, respectively, and dissolved organic carbon (DOC) concentration was 49% higher at the downstream Stennis Space Center (SSC) site. In addition, the bulk DOC pool at SSC had a higher colloidal fraction than at Bogalusa (75% vs. 68%). Detailed spatial surveys revealed the differences between the upstream and downstream stations resulted both from input from Hobolochitto Creek, a tributary of the EPR, and from influence of the swamp-rich floodplain. The contributions from Hobolochitto Creek to the carbon pool in the EPR basin were lowest during a high flow event and reached a maximum during the dry season. Meanwhile, the floodplain in the EPR basin acted as a significant sink for DOC, POC and particulate nitrogen during summer and for suspended sediment during a high flow event. However, the floodplain was converted into a source of suspended sediment, DOC, and POC to the EPR during winter, revealing a dynamic nature and seasonality in the floodplain influence. Consistent with its dominant forest coverage, abundant wetlands along the river corridor, and mild anthropogenic disturbance, the Pearl River basin above Bogalusa generally had higher yields of DOC and POC (1903 and 1386 kg-C km-2 yr-1, respectively), but a lower yield of DIC (2126 kg-C km-2 yr-1) compared to other North American rivers. An estimation based on a mass balance approach suggests the interactions between floodplain and the main river stem could reduce the annual DIC and POC export fluxes from downstream of the EPR by 24% and 40

  20. How do long-term development and periodical changes of river-floodplain systems affect the fate of contaminants? Results from European rivers.

    PubMed

    Lair, G J; Zehetner, F; Fiebig, M; Gerzabek, M H; van Gestel, C A M; Hein, T; Hohensinner, S; Hsu, P; Jones, K C; Jordan, G; Koelmans, A A; Poot, A; Slijkerman, D M E; Totsche, K U; Bondar-Kunze, E; Barth, J A C

    2009-12-01

    In many densely populated areas, riverine floodplains have been strongly impacted and degraded by river channelization and flood protection dikes. Floodplains act as buffers for flood water and as filters for nutrients and pollutants carried with river water and sediment from upstream source areas. Based on results of the EU-funded "AquaTerra" project (2004-2009), we analyze changes in the dynamics of European river-floodplain systems over different temporal scales and assess their effects on contaminant behaviour and ecosystem functioning. We find that human-induced changes in the hydrologic regime of rivers have direct and severe consequences on nutrient cycling and contaminant retention in adjacent floodplains. We point out the complex interactions of contaminants with nutrient availability and other physico-chemical characteristics (pH, organic matter) in determining ecotoxicity and habitat quality, and draw conclusions for improved floodplain management.

  1. How do long-term development and periodical changes of river-floodplain systems affect the fate of contaminants? Results from European rivers.

    PubMed

    Lair, G J; Zehetner, F; Fiebig, M; Gerzabek, M H; van Gestel, C A M; Hein, T; Hohensinner, S; Hsu, P; Jones, K C; Jordan, G; Koelmans, A A; Poot, A; Slijkerman, D M E; Totsche, K U; Bondar-Kunze, E; Barth, J A C

    2009-12-01

    In many densely populated areas, riverine floodplains have been strongly impacted and degraded by river channelization and flood protection dikes. Floodplains act as buffers for flood water and as filters for nutrients and pollutants carried with river water and sediment from upstream source areas. Based on results of the EU-funded "AquaTerra" project (2004-2009), we analyze changes in the dynamics of European river-floodplain systems over different temporal scales and assess their effects on contaminant behaviour and ecosystem functioning. We find that human-induced changes in the hydrologic regime of rivers have direct and severe consequences on nutrient cycling and contaminant retention in adjacent floodplains. We point out the complex interactions of contaminants with nutrient availability and other physico-chemical characteristics (pH, organic matter) in determining ecotoxicity and habitat quality, and draw conclusions for improved floodplain management. PMID:19604610

  2. Nitrate loss from a restored floodplain on the lower Cosumnes River, California

    NASA Astrophysics Data System (ADS)

    Sheibley, R. W.; Ahearn, D. S.; Santoriello, P.; Dahlgren, R. A.

    2002-12-01

    Floodplain habit was recreated on the lower Cosumnes River by breaching levees that previously protected agricultural lands from seasonal flooding. This study examined the ability of restored floodplains to retain nutrients from the river during flood events. The study looked at the potential for nitrate loss utilizing two techniques: (i) potential denitrification rates of floodplain soils and (ii) nitrate loss from floodplain waters during in situ microcosm experiments. Soils samples were collected from 13 locations within the floodplain and analyzed for denitrification potential. Denitrification potentials ranged from 0.06 to 27.5 nmol N2O cm-3 hr-1 and correlated with the concentrations of total N, organic C, sand and silt in the soils. Furthermore, denitrification potential correlated well with microbial respiration rates suggesting that concentrations of labile carbon strongly affect microbial activity and subsequent denitrification. Microcosm experiments were conducted by inserting polycarbonate tubes approximately 20 cm into the sediment. In addition, a replicate set of columns was studied which excluded the sediment layer to distinguish water column processes from those occurring within the sediments. The overlying water was spiked with nitrate and bromide to observe changing nitrate concentrations over time. Three different levels of nitrate were examined: ambient, +1 ppm nitrate, and +5 ppm nitrate. Results showed that nitrate loss from the water column was rapid and a function of the initial nitrate concentration. Nitrate was completely removed within 68 to 163 hours for the background and +5ppm treatments, respectively. Rates of nitrate disappearance were ~ 2.5 times greater in the sediment/water treatment, with approximately 20-30% of the nitrate being lost from water column alone. Results from this study document the potential role of these floodplain habitats to reduce the amount of nitrate that is transported downstream to sensitive aquatic

  3. Living in highly dynamic polluted river floodplains, do contaminants contribute to population and community effects?

    PubMed

    Klok, Chris; Kraak, Michiel H S

    2008-12-01

    The aim of this paper was to collect evidence for the effects of contaminants on biota in a highly dynamic river Rhine floodplain. To this purpose we reviewed the results of circa 10 studies performed in this floodplain. The floodplain was contaminated with elevated levels of cadmium, copper, PAHs, and PCBs and high levels of zinc which were at some sites above legislative values. The results showed that the present contaminants were accumulated by the floodplain inhabiting organisms, but meanwhile population and community effects were ambiguous. Only for the mayfly Ephoron virgo clear effects were detected at the level of the single floodplain. The absence of clear population and community effects is puzzling since at lower contaminant concentrations adverse effects were detected in other environments. Factors that may mask toxic effects include flooding and food quality and quantity. We conclude that given the site specific conditions, being an open, eutrophic system with a highly dynamic flooding pattern, assessment of the contribution of toxicants to observed population density or biomass and community composition requires 1] an increase in number of replicates; 2] a larger scale of investigation and 3] comparison to stable systems with comparable contamination levels.

  4. Do beaver dams reduce habitat connectivity and salmon productivity in expansive river floodplains?

    PubMed

    Malison, Rachel L; Kuzishchin, Kirill V; Stanford, Jack A

    2016-01-01

    Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3-12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99-1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically

  5. Do beaver dams reduce habitat connectivity and salmon productivity in expansive river floodplains?

    PubMed Central

    Kuzishchin, Kirill V.; Stanford, Jack A.

    2016-01-01

    Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3–12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99–1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically

  6. Do beaver dams reduce habitat connectivity and salmon productivity in expansive river floodplains?

    PubMed

    Malison, Rachel L; Kuzishchin, Kirill V; Stanford, Jack A

    2016-01-01

    Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3-12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99-1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically

  7. Do beaver dams reduce habitat connectivity and salmon productivity in expansive river floodplains?

    PubMed Central

    Kuzishchin, Kirill V.; Stanford, Jack A.

    2016-01-01

    Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3–12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99–1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically

  8. Response of fishes to floodplain connectivity during and following a 500-year flood event in the unimpounded upper Mississippi River

    USGS Publications Warehouse

    Barko, V.A.; Herzog, D.P.; O'Connell, M. T.

    2006-01-01

    We examined data collected on fish assemblage structure among three differing floodplain types (broad, moderate, and narrow) during the 1993 flood in the unimpounded reach of the upper Mississippi River. This 500 year flood event provided a unique opportunity to investigate fish-floodplain function because the main river channel is otherwise typically disjunct from approximately 82% of its floodplain by an extensive levee system. Fishes were sampled during three separate periods, and 42 species of adult and young-of-the-year (YOY) fishes were captured. Analysis of similarity (ANOSIM) revealed a significant and distinguishable difference between both adult and YOY assemblage structure among the three floodplain types. Analysis of variance revealed that Secchi transparency, turbidity, water velocity, and dissolved oxygen were significantly different among the floodplain types. However, only depth of gear deployment and Secchi transparency were significantly correlated with adult assemblage structure. None of these variables were significantly correlated with YOY assemblage structure. The numerically abundant families (adult and YOY catches combined) on the floodplain included Centrarchidae, Ictularidae, and Cyprinidae. Both native and non-native fishes were captured on the floodplain, and several of the numerically abundant species that were captured on the floodplain peaked in catch-per-unit-effort 1-3 years after the 1993 flood event. This suggests that some species may have used flooded terrestrial habitat for spawning, feeding, or both. The findings from our study provide much needed insight into fish-floodplain function in a temperate, channelized river system and suggest that lateral connectivity of the main river channel to less degraded reaches of its floodplain should become a management priority not only to maintain faunal biodiversity but also potentially reduce the impacts of non-native species in large river systems.

  9. Using ²¹⁰Pb measurements to estimate sedimentation rates on river floodplains.

    PubMed

    Du, P; Walling, D E

    2012-01-01

    Growing interest in the dynamics of floodplain evolution and the important role of overbank sedimentation on river floodplains as a sediment sink has focused attention on the need to document contemporary and recent rates of overbank sedimentation. The potential for using the fallout radionuclides ¹³⁷Cs and excess ²¹⁰Pb to estimate medium-term (10-10² years) sedimentation rates on river floodplains has attracted increasing attention. Most studies that have successfully used fallout radionuclides for this purpose have focused on the use of ¹³⁷Cs. However, the use of excess ²¹⁰Pb potentially offers a number of advantages over ¹³⁷Cs measurements. Most existing investigations that have used excess ²¹⁰Pb measurements to document sedimentation rates have, however, focused on lakes rather than floodplains and the transfer of the approach, and particularly the models used to estimate the sedimentation rate, to river floodplains involves a number of uncertainties, which require further attention. This contribution reports the results of an investigation of overbank sedimentation rates on the floodplains of several UK rivers. Sediment cores were collected from seven floodplain sites representative of different environmental conditions and located in different areas of England and Wales. Measurements of excess ²¹⁰Pb and ¹³⁷Cs were made on these cores. The ²¹⁰Pb measurements have been used to estimate sedimentation rates and the results obtained by using different models have been compared. The ¹³⁷Cs measurements have also been used to provide an essentially independent time marker for validation purposes. In using the ²¹⁰Pb measurements, particular attention was directed to the problem of obtaining reliable estimates of the supported and excess or unsupported components of the total ²¹⁰Pb activity of sediment samples. Although there was a reasonable degree of consistency between the estimates of sedimentation rate provided by

  10. Decadal sediment accumulation rates on the floodplain of the Strickland River, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Swanson, K. M.; Watson, E.; Aalto, R.; Lauer, J. W.; Bera, M. T.; Marshall, A.; Taylor, M.; Apte, S. C.; Dietrich, W. E.

    2006-12-01

    Rate of aggradation and infilling of accommodation space along lowland channels in response to post-glacial sea level rise should depend on sediment supply. The Strickland and Fly Rivers join at just 6 m above sea level, and the Strickland has historically carried about 7 times the sediment load and twice the river discharge as the Fly. Here we test the hypothesis that the lowland Strickland River floodplain should now have a lower sediment trap efficiency (due to more fully developed floodplains) than the middle Fly River, which currently losses about 40% of its load to the floodplain annually. We use mine-derived elevated Pb and Ag in floodplain core samples to determine the rates of sedimentation across the lower Strickland floodplain. Field sampling campaigns were conducted in 1997 and 2003, collecting shallow (less than 1 m) core samples at 5 relatively straight reaches up to 2 km from channel banks (in 1997 and 2003) and from 3 strongly curved sections, as well as from other sites of interest (2003). Various observations indicate that the concentration of particulate metals in overbank floods varies with stage, drought-flood cycles, and through the life of the mine. Sediment accumulation declines across the floodplain from the channel bank with an average rate of about 1.4 cm/yr over the first 1 km. Some sedimentation farther out did occur but is not well defined by our data. Overbank deposition is about 13% of the total load. Sedimentation rate per unit area is perhaps 10 times that measured on the Fly, but lateral migration on the Strickland is sufficiently high (average 5 m/yr) that overbank deposits are returned to the channel, significantly reducing potential net deposition to the floodplain. We conclude that the Strickland, which is nearly 10 times steeper than the Fly, and has much higher overbank deposition rates, nonetheless has less net deposition than the Fly because of the more vigorous lateral migration (which apparently results from the higher

  11. Deposition and fate of organic carbon in floodplains along a tropical semi-arid lowland river (Tana River, Kenya)

    NASA Astrophysics Data System (ADS)

    Omengo, Fred; Geeraert, Naomi; Boullion, Steven; Govers, Gerard

    2016-04-01

    Inland organic carbon (OC) burial by sedimentation has recently been shown to be an important component in river catchment carbon(C) budget. However, data on OC burial by sedimentation are hitherto largely limited to temperate zones. We investigated the deposition and fate of sediment-associated OC in the floodplains of a tropical lowland Tana river (Kenya), between two main gauging stations (Garissa and Garsen). Freshly deposited surface sediments and sediment cores were sampled and analysed for OC and total nitrogen content, stable isotope signatures (δ13C) of OC, and grain size distribution. In addition, we incubated sediment cores to quantify CO2 production as a proxy of OC mineralization. The floodplain receives sediment with a relatively low OC content (1.56±0.42%), sediments are enriched with OC inputs from floodplain vegetation to levels above 3%. Sediment cores show a sharp decrease of OC with depth, from 3 - 12%C in the (sub) surface to less than 1%OC below ~60cm depth. Relatively high and deep OC mineralization rates (0.14±0.07mol CO2 kg-1C d-1) were recorded. We used our data to make a first assessment of the carbon burial efficiency of the Tana river floodplain: in contrast to what is observed in temperate environments, over 50% of carbon present in the top layers is lost in less than a century. While significant amounts of OC are deposited in the Tana river floodplain, the high post-depositional loss limits the long-term C sink.

  12. Flood variability recorded by crevasse-splay sedimentation of large river floodplains

    NASA Astrophysics Data System (ADS)

    Hackney, C. R.; Darby, S. E.; Aalto, R. E.; Parsons, D. R.; Clayton, A.; Schwendel, A.; Leyland, J.; Nicholas, A. P.; Best, J.

    2015-12-01

    During rapid rise flood events, crevasse-splay complexes are a key conduit through which sediment and water are passed from the main channel onto the floodplain, particularly for large rivers. These crevasse-splay systems may therefore be key loci of floodplain sedimentation, as well as conditioning the location of avulsions. As such they may preserve climatic signals within the depositional record of large alluvial rivers. Despite recent advances in our capabilities to model the development and evolution of these systems, our understanding of the passage, storage and reworking of water and sediment across them remains relatively poor. A key limitation concerns the point that, since floodplain topography is a first-order control on the hydrodynamics of crevasse-splays, publicly available topographic data sets (e.g. SRTM, ASTER) are currently unable to resolve key processes at the necessary spatial resolution. Here we employ Structure-from-Motion (SfM) on low-level aerial photography to obtain high-resolution (3m grid cell) georectified topographic data (horizontal error = 0.02 m; vertical error = 0.2 m) for a representative crevasse-splay complex (27 km2) located along the Mekong River, Cambodia. We use the coupled hydrodynamic and morphodynamic model, Delft-3D to simulate sedimentation patterns for a series of idealised and observed rapid-rise flood events. We model floodplain deposition and erosion and validate simulated spatial and temporal variations against observed patterns of sedimentation determined through analysis of 210Pb geochronology of a network of floodplain cores and in-situ, post-event surface scrapings.

  13. NDVI patterns as indicator of morphodynamic activity in the middle Paraná River floodplain

    NASA Astrophysics Data System (ADS)

    Marchetti, Z. Y.; Minotti, P. G.; Ramonell, C. G.; Schivo, F.; Kandus, P.

    2016-01-01

    This work assesses the performance of a 2000-2014 NDVI-MODIS time-series to identify areas of the Paraná River floodplain associated with different morphodynamic areas and hence ecological behavior. From classification procedures we obtained six NDVI patterns (P1 to P6) differing in their mean values, standard deviation, and seasonality. The NDVI patterns are evidence of different situations in terms of elevation, flood dynamics, and vegetation physiognomies: P1 represents water bodies, P2 to P4 cover frequently flooded lowlands colonized by marshy vegetation, and P5 and P6 are placed on middle and high elevations that are less flooded and also are covered by tall vegetation (grassland and forest). Instead of differences among the six NDVI patterns, they showed a spatial arrangement that allowed the identification of two parallel belts; belt I, formed by P2 to P4, is placed close to the Paraná River and its connected branches; while belt II, formed by P5 and mainly P6, appears on the marginal floodplain far away from the main channels. The spatial arrangement of the two belts is similar to limits followed by the morphodynamic areas of the Paraná fluvial system. More than 60% of the surface covered by P2 and P5 corresponds to low morphodynamic areas while nearly 70% of P6 matches with high morphodynamic areas. Through their annual and interannual behavior, spatial arrangement, and relationship with morphodynamic areas, the NDVI patterns allow the interpretation of lateral organization of the Paraná River floodplain. This paper exploits the potential of time-series of NDVI to understand, from a synoptic point of view, the floodplain dynamics by capturing the seasonal and interannual variability of vegetation physiognomies and hydrosedimentological regime along and across the floodplain.

  14. Mercury speciation in floodplain soils and sediments along a contaminated river transect

    SciTech Connect

    Wallschlaeger, D.; Desai, M.V.M.; Spengler, M.; Wilken, R.D.

    1998-09-01

    A novel mercury-specific sequential extraction procedure (SEP) for the assessment of mercury (Hg) speciation in soils and sediments, with emphasis on studying the interaction between Hg and organic matter (OM), was developed and tested. It was applied to determine Hg speciation in floodplain topsoils and surface sediments along the Hg-contaminated part of the river Elbe, and to simultaneously derive some information on the (re)mobilization potentials for Hg from these matrices. The majority of the total Hg in the ecosystem today is bound in the floodplains, which also still geographically reflect the historic emission record. Most of the Hg in both matrices is bound strongly to OM, suggesting low availability. However, distinct differences between Hg speciation in the floodplain soils and sediments were also discovered. Mercury deposited in the floodplains shows speciation patterns that indicate stronger fixation compared with Hg in the sediments. This difference is attributed to the association of Hg with larger quantities of OM, which presumably also has higher molecular weight (MW). By comparison, Hg in the sediments was distributed among weaker binding forms, which are more likely to liberate Hg. Particularly, sediments showed a total lack of sulfidic binding forms for Hg. Pronounced geographical trends were detected in the Hg speciation along the river transect, with a general downstream shift from weaker to stronger binding forms, probably due to increased association with OM. These studies indicate that Hg speciation in riverine ecosystems is dynamic and reflects the chemical mechanisms underlying (bio) geochemical processes like distribution and transport.

  15. Rates of floodplain accretion in a tropical island river system impacted by cyclones and large floods

    NASA Astrophysics Data System (ADS)

    Terry, James P.; Garimella, Sitaram; Kostaschuk, Ray A.

    2002-01-01

    Fluvial processes, especially rates of floodplain accretion, are less well understood in the wet tropics than in other environments. In this study, the caesium-137 ( 137Cs) method was used to examine the recent historical sedimentation rate on the floodplain of the Wainimala River, in the basin of the Rewa River, the largest fluvial system in Fiji and the tropical South Pacific Islands. 137Cs activity in the floodplain stratigraphy showed a well-defined profile, with a clear peak at 115 cm depth. Our measured accretion rate of 3.2 cm year -1 over the last ca. 45 years exceeds rates recorded in humid regions elsewhere. This is explained by the high frequency of tropical cyclones near Fiji (40 since 1970) which can produce extreme rainfalls and large magnitude floods. Since the beginning of hydrological records, large overbank floods have occurred every 2 years on average at the study site. The biggest floods attained peak flows over 7000 m 3 s -1, or six times the bankfull discharge. Concentrations of suspended sediments are very high (max. 200-500 g l -1), delivered mainly by channel bank erosion. In the future, climatic change in the tropical South Pacific region may be associated with greater tropical cyclone intensities, which will probably increase the size of floods in the Rewa Basin and rates of floodplain sedimentation.

  16. Soils of floodplains in arid regions of Inner Asia (the Zavkhan River, Mongolia)

    NASA Astrophysics Data System (ADS)

    Ubugunov, L. L.; Ubugunova, V. I.

    2012-03-01

    The environmental conditions of soil formation and the diversity and classification position of soils developing on the Zavkhan River floodplain are considered, and the morphogenetic and agrochemical properties of these soils are characterized. It is shown that the conditions of soil formation on the floodplain of the Zavkhan River are specified by the mountainous topography, the effect of the large Mongol Els sand massif, the character of the alluviation processes, the groundwater level and salinity, and the regime of floods. The position of the floodplain in the system of altitudinal zones largely dictates the character of the soil cover pattern. In terms of the new Russian soil classification system, the soils studied belong to three trunks, four orders, and seven types: stratified humus alluvial soils, light-humus alluvial soils, light-humus quasigley alluvial soils, light-humus stratozems, and solonchaks. The soils of floodplain ecosystems in arid regions are characterized by low fertility. For their efficient use for pasturing and crop growing, the ecologically balanced differentiated application of manure, mineral fertilizers (NPK), and some microelements is required.

  17. Vegetation and its relationship with geomorphologic units in the Parana River floodplain, Argentina

    NASA Astrophysics Data System (ADS)

    Marchetti, Z. Y.; Latrubesse, E. M.; Pereira, M. S.; Ramonell, C. G.

    2013-10-01

    The Parana River is one of the most important fluvial systems of South America and its floodplain includes the most diverse subtropical ecosystem on the continent. However, the relationship between basic aspects, such as the vegetation and geomorphology of the river floodplain, has scarcely been investigated. In this paper, the annual dynamics of vegetation in relation to the geomorphologic and hydrological characteristics of a river floodplain around 31° 30' S, are analyzed. The annual dynamics of vegetation was investigated using values of the Normalized Difference Vegetation Index (NDVI) obtained from satellite images at two scales of spatial analysis: the first, at the geomorphologic unit level, through several transects crossing the total width of each unit and, the second, through some transects selected from each unit. Our analysis considered variables of different temporal stability (such as geomorphology, hydrology, vegetation, precipitation, and ground temperature), using scenes corresponding to two hydrological cycles of the system (2009 and 2010), which represented relatively "dry" and "humid" years. Five main geomorphologic units were identified in the floodplain of this anabranching system, which were named considering the predominant landforms and the most important (or typical) water course of each area: Bars and Islands of the Main Channel of the Parana River (BI-MCH), Scroll Bars of the Colastine Branch (SB-C), Scroll Bars of the San Javier River Channel (SB-SJ), Crevasse Splays and Levees of the Malo-Mendieta minor channels (CSL-MM), and Crevasse Splays and Levees of the Santa Fe-Coronda river channels (CSL-SFC). These major units are assembled at different general levels and with variable slopes, which partially control the permanence and other characteristics of the flood flow. The crevasse splays and river levees units were predominantly characterized by herbaceous-bushy marshy vegetation, with low mean NDVI values, while SB-C and BI

  18. Strategic Floodplain Reconnection Along the Lower Tisza and Lower Illinois Rivers: Identifying Opportunities, Tradeoffs, and Limitations

    NASA Astrophysics Data System (ADS)

    Guida, R.; Remo, J. W.; Secchi, S.; Swanson, T.; Kiss, T.

    2015-12-01

    During the late 19th and into the 20th Centuries, the Tisza and Illinois Rivers were highly altered through the construction of levees and dams to reclaim their floodplain-wetland systems for agriculture and to facilitate navigation. In recent decades, flood levels have continued to rise due to aggradation on the confined floodplains reducing flood-conveyance capacity. As a result, "Room for the River" proposals have gained more prominence. Our overarching hypothesis is that strategically reconnecting these rivers to their floodplains will reduce flood levels and increase ecological habitat while limiting socioeconomic impacts. In this study, we assessed several reconnection scenarios, including levee setbacks and removals, for the Lower Tisza River (LTR; Hungary) and the Lower Illinois River (LIR; Illinois, USA). To model water-surface elevations (WSELs) for the 5- through 500-year flood events, we employed HEC-RAS (1D) and SOBEK (1D/2D) hydraulic models. To determine socioeconomic tradeoffs using these modeled WSELs, we developed a corresponding suite of expected annual damages (EADs) using FEMA's Hazus-MH flood-loss modeling software for buildings and integrated geospatial and soil productivity indices to estimate agricultural losses. To assess ecosystem benefits of reconnection along the LTR, we used historic wetland extent as a proxy for increasing needed floodplain habitats. For the LIR, we performed habitat screening using Land Capability Potential Index and other assessment tools to estimate potential ecosystem benefits. Results indicate that levee removal and/or setbacks may reduce flood heights up to 1.6 m along the LTR and over 1.0 m along the LIR. While urban areas have the highest EADs, several lower-production agricultural areas show potential for reducing flood heights while minimizing damages. Strategic-floodplain reconnection benefits along the LTR and LIR include over half of historically-significant wetlands being reconnected and the creation of

  19. Use of isotopes to study floodplain wetland and river flow interaction in the White Volta River basin, Ghana.

    PubMed

    Nyarko, Benjamin Kofi; Kofi Essumang, David; Eghan, Moses J; Reichert, Barbara; van de Giesen, Nick; Vlek, Paul

    2010-03-01

    Floodplain wetlands influence the timing and magnitude of stream responses to rainfall. In managing and sustaining the level of water resource usage in any river catchment as well as when modelling hydrological processes, it is essential that the role of floodplain wetlands in stream flows is recognised and understood. Existing studies on hydrology within the Volta River basin have not adequately represented the variability of wetland hydrological processes and their contribution to the sustenance of river flow. In order to quantify the extent of floodwater storage within riparian wetlands and their contribution to subsequent river discharges, a series of complementary studies were conducted by utilising stable isotopes, physical monitoring of groundwater levels and numerical modelling. The water samples were collected near Pwalugu on the White Volta River and at three wetland sites adjacent to the river using the grab sampling technique. These were analysed for (18)O and (2)H. The analysis provided an estimate of the contribution of pre-event water to overall stream flow. In addition, the variation in the isotopic composition in the river and wetland water samples, respectively, revealed the pattern of flow and exchange of water between the wetlands and the main river system. PMID:20229387

  20. Use of isotopes to study floodplain wetland and river flow interaction in the White Volta River basin, Ghana.

    PubMed

    Nyarko, Benjamin Kofi; Kofi Essumang, David; Eghan, Moses J; Reichert, Barbara; van de Giesen, Nick; Vlek, Paul

    2010-03-01

    Floodplain wetlands influence the timing and magnitude of stream responses to rainfall. In managing and sustaining the level of water resource usage in any river catchment as well as when modelling hydrological processes, it is essential that the role of floodplain wetlands in stream flows is recognised and understood. Existing studies on hydrology within the Volta River basin have not adequately represented the variability of wetland hydrological processes and their contribution to the sustenance of river flow. In order to quantify the extent of floodwater storage within riparian wetlands and their contribution to subsequent river discharges, a series of complementary studies were conducted by utilising stable isotopes, physical monitoring of groundwater levels and numerical modelling. The water samples were collected near Pwalugu on the White Volta River and at three wetland sites adjacent to the river using the grab sampling technique. These were analysed for (18)O and (2)H. The analysis provided an estimate of the contribution of pre-event water to overall stream flow. In addition, the variation in the isotopic composition in the river and wetland water samples, respectively, revealed the pattern of flow and exchange of water between the wetlands and the main river system.

  1. Groundwater Surface Water Interactions in a Gold-Mined Dredged Floodplain of the Merced River

    NASA Astrophysics Data System (ADS)

    Sullivan, L.; Conklin, M. H.; Ghezzehei, T. A.

    2012-12-01

    The Merced River, originating in the Sierra Nevada, California, drains a watershed with an area of ~3,305 km2. Merced River has been highly altered due to diversions, mechanically dredged mining, and damming. A year of groundwater-surface water interactions were studied to elucidate the hydrological connection between the Main Canal, an unlined canal that contains Merced River water flows parallel to the river with an average elevation of 89m, the highly conductive previously dredged floodplain, and the Merced River with an average elevation of 84m. Upstream of the study reach, located in an undredged portion, of the floodplain are two fish farms that have been operating for approximately 40 years. This study reach has been historically important for salmon spawning and rearing, where more than 50% of the Chinook salmon of the Merced River spawn. Currently salmon restoration is focusing gravel augmentation and adding side channel and ignoring groundwater influences. Exchanges between the hyporheic and surrounding surface, groundwater, riparian, and alluvial floodplain habitats occur over a wide range of spatial and temporal scales. Pressure transducers were installed in seven wells and four ponds located in the dredged floodplain. All wells were drilled to the Mehrten Formation, a confining layer, and screened for last 3m. These groundwater well water levels as well as the surface water elevations of the Main Canal and the Merced River were used to determine the direction of sublateral surface flows using Groundwater Vistas as a user interface for MODFLOW. The well and pond waters and seepage from the river banks were sampled for anion/cation, dissolved organic carbon, total nitrogen, total iron, and total dissolved iron concentrations to determine water sources and the possibility of suboxic water. Field analysis indicated that water in all wells and ponds exhibit low dissolved oxygen, high conductivity rates, and oxidation/reduction potentials that switched from

  2. Seasonal bioavailability of sediment-associated heavy metals along the Mississippi river floodplain.

    PubMed

    Grabowski, L A; Houpis, J L; Woods, W I; Johnson, K A

    2001-11-01

    A value of simultaneously extracted metal to acid-volatile sulfide (SEM-AVS) can provide important information regarding metal availability in anaerobic sediment. SEM and AVS concentrations were obtained by the cold-acid purge-and-trap technique during spring and summer at six locations along the Mississippi River floodplain. SEM-AVS values and AVS concentrations did not vary significantly between locations during both seasons. AVS concentrations were significantly greater during summer than spring, resulting in significantly lower SEM-AVS values in summer. Total SEM concentrations did not significantly vary between seasons or specific locations. SEM-AVS values were greater than one at each location during both seasons. Sediment metal toxicity was predicted to be absent for benthic organisms along the river floodplain. PMID:11680760

  3. Trace metal dynamics in floodplain soils of the river Elbe: a review.

    PubMed

    Schulz-Zunkel, Christiane; Krueger, Frank

    2009-01-01

    This paper reviews trace metal dynamics in floodplain soils using the Elbe floodplains in Germany as an example of extraordinary importance because of the pollution level of its sediments and soils. Trace metal dynamics are determined by processes of retention and release, which are influenced by a number of soil properties including pH value, redox potential, organic matter, type and amount of clay minerals, iron-, manganese- and aluminum-oxides. Today floodplains act as important sinks for contaminants but under changing hydraulic and geochemical conditions they may also act as sources for pollutants. In floodplains such changes may be extremes in flooding or dry periods that particularly lead to altered redox potentials and that in turn influence the pH value, the mineralization of organic matter as well as the charge of the pedogenic oxides. Such reactions may affect the bioavailability of trace metals in soils and it can be clearly seen that the bioavailability of metals is an important factor for estimating trace metal remobilization in floodplain soils. However as bioavailability is not a constant factor, there is still a lack of quantification of metal mobilization particularly on the basis of changing geochemical conditions. Moreover, mobile amounts of metals in the soil solution do not indicate to which extent remobilized metals will be transported to water bodies or plants and therefore potentially have toxicological effects. Consequently, floodplain areas still need to be taken into consideration when studying the role and behavior of sediments and soils for transporting pollutants within river systems, particularly concerning the Water Framework Directive.

  4. Trace metal dynamics in floodplain soils of the river Elbe: a review.

    PubMed

    Schulz-Zunkel, Christiane; Krueger, Frank

    2009-01-01

    This paper reviews trace metal dynamics in floodplain soils using the Elbe floodplains in Germany as an example of extraordinary importance because of the pollution level of its sediments and soils. Trace metal dynamics are determined by processes of retention and release, which are influenced by a number of soil properties including pH value, redox potential, organic matter, type and amount of clay minerals, iron-, manganese- and aluminum-oxides. Today floodplains act as important sinks for contaminants but under changing hydraulic and geochemical conditions they may also act as sources for pollutants. In floodplains such changes may be extremes in flooding or dry periods that particularly lead to altered redox potentials and that in turn influence the pH value, the mineralization of organic matter as well as the charge of the pedogenic oxides. Such reactions may affect the bioavailability of trace metals in soils and it can be clearly seen that the bioavailability of metals is an important factor for estimating trace metal remobilization in floodplain soils. However as bioavailability is not a constant factor, there is still a lack of quantification of metal mobilization particularly on the basis of changing geochemical conditions. Moreover, mobile amounts of metals in the soil solution do not indicate to which extent remobilized metals will be transported to water bodies or plants and therefore potentially have toxicological effects. Consequently, floodplain areas still need to be taken into consideration when studying the role and behavior of sediments and soils for transporting pollutants within river systems, particularly concerning the Water Framework Directive. PMID:19465710

  5. The role of run-of-river impoundments in CO2 and CH4 emissions from floodplains of the Delaware Piedmont, Christina River Basin Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Pearson, A.; Pizzuto, J. E.; Vargas, R.

    2014-12-01

    There is strong interest in understanding how run-of-river impoundments affect streams and their floodplains. Most recent work has focused on the fate of sediment within these dammed systems both past and current, the geomorphic impacts associated with sediment, and issues associated with removing run-of-the-river dams. Here, we assess how run-of-river impoundments alter the floodplain effluxes of carbon dioxide (CO2), and methane (CH4). We sampled two pairs of floodplains on the Red Clay Creek (140 km2) located in the Christina River Basin Critical Zone Observatory. The floodplain pairs were centered on a current and a former location of a run-of-river dam (one floodplain upstream, one downstream of dam location). Each floodplain was subjected to a suite of measurements that included bi-weekly gas flux (CO2, CH4, and H2O), bi-weekly soil moisture and temperature, monthly biomass sampling, C/N ratio sampling from O and A horizons, and cores that constrain the total organic carbon and nitrogen at depth as well as provide a description of the stratigraphy. Preliminary findings show that all floodplains are sources of CH4 (0.18 - 1.12 nmol m-2s-1) and CO2 (0.42 - 3.12 µmol m-2s-1). Despite temporal variability, the upstream floodplains produce more CH4 and CO2 than downstream floodplains. Our results may suggest that run-of-the-river dams enhance release of carbon from floodplains into the atmosphere.

  6. Variable enzymatic activity of prokaryotes under different hydrological settings in a river floodplain of the Danube

    NASA Astrophysics Data System (ADS)

    Sieczko, Anna; Meisterl, Karin; Peduzzi, Peter

    2013-04-01

    This study tackles the role of different hydrological settings in a river-floodplain for organic matter processing by bacteria. Sampling locations in the Danube river-floodplain near Vienna (Austria) were chosen in a way that they represent a gradient of connectivity to the main river. We focused on the influence of variable hydrological connectivity and retention on microbial substrate utilization in the different subsystems of this river-floodplain section. We investigated extracellular enzymatic activity (EEA) both associated with particles (PA) and in the ambient water (FL). The activity of six enzymes was assessed: enzymes involved in the metabolism of carbon (β-d-glucosidase, α-d-glucosidase, β-d-xylosidase, cellobiohydrolase), peptide (endopeptidase [Endo]) and for degradation of refractory lignin material (phenol oxidase [PhOx]). We hypothesized that the degree of connectivity and water exchange in floodplain lakes influences prokaryotic enzymatic activity and productivity both on particles and in the surrounding water. The strong correlation between endopeptidase and phenol oxidase of the FL fraction in all locations suggests a tight coupling of enzymes responsible for utilization of labile and refractory material. Our results indicate that particle-associated bacterial growth in frequently flooded locations was supported by allochthonous carbon derived from polysaccharide hydrolysis, whereas in isolated locations, bacterial biomass was fuelled with carbon obtained largely from lignin utilization. This implies that prolonged residence time in isolated locations allows more refractory material to be utilized. Most of the enzymes (PA and FL) did not show clear dependencies on the degree of connectivity. However, phenol oxidase displayed an interesting pattern: activity of PhOx in ambient water decreased, whereas PA PhOx increased, together with the degree of connectivity. The study also demonstrates enhanced metabolism of the PA bacterial community and a

  7. Dams, floodplain land use, and riparian forest conservation in the semiarid Upper Colorado River Basin, USA

    USGS Publications Warehouse

    Andersen, D.C.; Cooper, D.J.; Northcott, K.

    2007-01-01

    Land and water resource development can independently eliminate riparian plant communities, including Fremont cottonwood forest (CF), a major contributor to ecosystem structure and functioning in semiarid portions of the American Southwest. We tested whether floodplain development was linked to river regulation in the Upper Colorado River Basin (UCRB) by relating the extent of five developed land-cover categories as well as CF and other natural vegetation to catchment reservoir capacity, changes in total annual and annual peak discharge, and overall level of mainstem hydrologic alteration (small, moderate, or large) in 26 fourth-order subbasins. We also asked whether CF appeared to be in jeopardy at a regional level. We classified 51% of the 57,000 ha of alluvial floodplain examined along >2600 km of mainstem rivers as CF and 36% as developed. The proportion developed was unrelated to the level of mainstem hydrologic alteration. The proportion classified as CF was also independent of the level of hydrologic alteration, a result we attribute to confounding effects from development, the presence of time lags, and contrasting effects from flow alteration in different subbasins. Most CF (68% by area) had a sparse canopy (???5% cover), and stands with >50% canopy cover occupied <1% of the floodplain in 15 subbasins. We suggest that CF extent in the UCRB will decline markedly in the future, when the old trees on floodplains now disconnected from the river die and large areas change from CF to non-CF categories. Attention at a basinwide scale to the multiple factors affecting cottonwood patch dynamics is needed to assure conservation of these riparian forests. ?? 2007 Springer Science+Business Media, LLC.

  8. Coevolution of floodplain and riparian forest dynamics on large, meandering rivers

    NASA Astrophysics Data System (ADS)

    Stella, J. C.; Riddle, J. D.; Battles, J. J.

    2012-12-01

    On large meandering rivers, riparian forests coevolve with the floodplains that support them. Floodplain characteristics such as local disturbance regime, deposition rates and sediment texture drive plant community dynamics, which in turn feed back to the abiotic processes. We investigated floodplain and riparian forest coevolution along the along the Sacramento River (California, USA), a large, mediterranean-climate river that has been extensively regulated for 70 years, but whose 160-km middle reach (Red Bluff to Colusa) retains some channel mobility and natural forest stands. Guided by maps of floodplain change over time and current vegetation cover, we conducted an extensive forest inventory and chronosequence analysis to quantify how abiotic conditions and forest structural characteristics such as tree density, basal area and biomass vary with floodplain age. We inventoried 285 fixed-area plots distributed across 19 large point bars within vegetation patches ranging in age from 4 to 107 years. Two successional trajectories were evident: (1) shifting species dominance over time within forested areas, from willow to cottonwood to walnut, boxelder and valley oak; and (2) patches of shrub willow (primarily Salix exigua) that maintained dominance throughout time. Sediment accretion was reduced in the persistent willow plots compared to the successional forest stands, suggesting an association between higher flood energy and arrested succession. Forested stands 40-60 years old were the most extensive across the chronosequence in terms of floodplain area, and supported the highest biomass, species diversity, and functional wildlife habitat. These stands were dominated by Fremont cottonwood (Populus fremontii) and reached their maxima in terms of tree size and biomass at age 50 years. The persistent willow stands reached their structural maxima earlier (32 years) and supported lower biomass. Basal area and abundance of large trees decreased in stands >90 years old

  9. Forest Types in the Lower Suwannee River Floodplain, Florida?-A Report and Interactive Map

    USGS Publications Warehouse

    Darst, M.R.; Light, H.M.; Lewis, L.J.; Sepulveda, A.A.

    2003-01-01

    A map of forest types in the lower Suwannee River floodplain, Florida, was created during a study conducted from 1996 to 2000 by the U.S. Geological Survey in cooperation with the Suwannee River Water Management District. The map is presented with this report on a compact disc with interactive viewing software. The forest map can be used by scientists for ecological studies in the floodplain based on land cover types and by landowners and management personnel making land use decisions. The study area is the 10-year floodplain of the lower Suwannee River from its confluence with the Santa Fe River to the lower limit of forests near the Gulf of Mexico. The floodplain is divided into three reaches: riverine (non-tidal), upper tidal, and lower tidal, due to changes in hydrology, vegetation, and soils with proximity to the coast. The 10-year floodplain covers about 21,170 hectares; nearly 88 percent of this area (18,580 hectares) is mapped as 14 major forest types. Approximately 29 percent (5,319 hectares) of these forests have been altered by agriculture or development. About 75 percent of the area of major forest types (13,994 hectares) is wetland forests and about 25 percent (4,586 hectares) is upland forests. Tidal wetland forests (8,955 hectares) cover a much greater area than riverine wetland forests (5,039 hectares). Oak/pine upland forests are present in the riverine and upper tidal reaches of the floodplain on elevations that are inundated only briefly during the highest floods. High bottomland hardwoods are present on the higher levees, ridges, and flats of the riverine reach where soils are usually sandy. Low bottomland hardwood forests are present in the riverine reach on swamp margins and low levees and flats that are flooded continuously for several weeks or longer every 1 to 3 years. Riverine swamps are present in the lowest and wettest areas of the non-tidal floodplain that are either inundated or saturated most of the time. Upper tidal bottomland

  10. Channel Pattern and the Intermediate Disturbance Hypothesis Predict Biodiversity in River-floodplain Ecosystems

    NASA Astrophysics Data System (ADS)

    Beechie, T.; Pollock, M.; Baker, S.; Morley, S.

    2005-05-01

    River-floodplain ecosystems are among the most diverse and dynamic environments in the world, yet mechanisms that regulate biodiversity in river corridors are poorly understood. In part, this stems from a lack of integration of geomorphological and biological concepts that link fluvial processes to biological diversity. Here we illustrate how channel pattern predicts biodiversity via the intermediate disturbance hypothesis (IDH). We show that (1) channel pattern predicts disturbance frequency and age diversity of patches, (2) there are distinct life history tradeoffs among colonizing and climax species, and (3) diversity should be highest in channel patterns with intermediate levels of disturbance. We first classify river-floodplains in northwestern USA using geomorphological channel patterns, and show how these patterns predict patch dynamics in river-floodplain systems. We then use space-for-time substitution to illustrate successional patterns of trees and aquatic invertebrates. Finally, we link reach-level patch dynamics to reach-level biodiversity of trees and aquatic invertebrates using the IDH. Patch age diversity is low in straight channels with low movement rates and mostly old surfaces, and low in braided channels with high movement rates and mostly young surfaces. Patch age diversity is highest in channels with intermediate movement rates (meandering and island-braided channels). Vegetation succession drives temporal patterns of biological diversity within individual terrestrial and aquatic patches (alpha diversity). Trees exhibit clear successional trade-offs as patches age, succeeding from hardwood-dominated at the colonizing stage to conifer-dominated at the climax stage. Highest within-patch species richness occurs at an intermediate age. Alpha diversity of aquatic invertebrates follows a similar pattern, probably in response to riparian forest succession and the shifting composition of detrital resources entering river and floodplain channels. We

  11. Assessment of flood-induced changes of phytoplankton along a river-floodplain system using the morpho-functional approach.

    PubMed

    Mihaljević, Melita; Spoljarić, Dubravka; Stević, Filip; Zuna Pfeiffer, Tanja

    2013-10-01

    In this research, we aimed to find out how the differences in hydrological connectivity between the main river channel and adjacent floodplain influence the changes in phytoplankton community structure along a river-floodplain system. The research was performed in the River Danube floodplain (Croatian river section) in the period 2008-2009 characterised by different flooding pattern on an annual time scale. By utilising the morpho-functional approach and multivariate analyses, the flood-derived structural changes of phytoplankton were analysed. The lake stability during the isolation phase triggered the specific pattern of morpho-functional groups (MFG) which were characterised by cyanobacterial species achieving very high biomass. Adversely, the high water turbulence in the lake during the frequent and extreme flooding led to evident similarity between lake and river assemblages. Besides different diatom species (groups of small and large centrics and pennates), which are the most abundant representatives in the river phytoplankton, many other groups such as cryptophytes and colonial phytomonads appeared to indicate altered conditions in the floodplain driven by flooding. Having different functional properties, small centric diatom taxa sorted to only one MFG cannot clearly reflect environmental changes that are shown by the species-level pattern. Disadvantages in using the MFG approach highlight that it is still necessary to combine it with taxonomical approach in monitoring of phytoplankton in the river-floodplain ecosystems.

  12. The Missing Link: the Role of Floodplain Tie Channels in Connecting Off River Water Bodies to Lowland Rivers

    NASA Astrophysics Data System (ADS)

    Rowland, J. C.; Dietrich, W. E.; Day, G.

    2005-05-01

    times in tie channel progradation rates. In a few instances Fly River tie channels have become filled with sediment following the increase in sediment loading. The precise role of tie channels in the ecology of lowland river systems has yet to be quantified, but given their critical role in connecting rivers with floodplain habitats it is likely they provide an important source of refuge, breeding habitat, and biomass production for many aquatic organisms. As restoration efforts increasingly focus on the improving or reestablishing connectivity between lowland rivers and their floodplains, consideration should be given as to whether tie channels are an important missing component of such systems.

  13. General classification handbook for floodplain vegetation in large river systems

    USGS Publications Warehouse

    Dieck, Jennifer J.; Ruhser, Janis; Hoy, Erin E.; Robinson, Larry R.

    2015-01-01

    This handbook describes the General Wetland Vegetation Classification System developed as part of the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration (UMRR) Program, Long Term Resource Monitoring (LTRM) element. The UMRR is a cooperative effort between the U.S. Army Corps of Engineers, U.S. Geological Survey, U.S. Fish and Wildlife Service, and the states of Illinois, Iowa, Minnesota, Missouri, and Wisconsin. The classification system consists of 31 general map classes and has been used to create systemic vegetation data layers throughout the diverse Upper Mississippi River System (UMRS), which includes the commercially navigable reaches of the Mississippi River from Minneapolis, Minnesota, in the north to Cairo, Illinois, in the south, the Illinois River, and navigable portions of the Kaskaskia, Black, St. Croix, and Minnesota Rivers. In addition, this handbook describes the evolution of the General Wetland Vegetation Classification System, discusses the process of creating a vegetation data layer, and describes each of the 31 map classes in detail. The handbook also acts as a pictorial guide to each of the map classes as they may appear in the field, as well as on color-infrared imagery. This version is an update to the original handbook published in 2004.

  14. Trace metal storage in recent floodplain sediments along the Dill River, central Germany

    NASA Astrophysics Data System (ADS)

    Martin, Charles W.

    2015-04-01

    Trace metals are stored in near-channel floodplain sediments along many rivers in industrial and mined watersheds of western European countries such as Germany. In this paper, I document the distribution of Cu, Pb, and Zn in 13 cores collected from near-channel floodplain sediments along a 25-km reach of the Dill River in central Germany. Mean concentrations of the three trace metals exceed background concentrations, an indication of anthropogenic enrichment along the study reach; many individual samples have concentrations several times the background levels and exceed standards for trace metals contained in the German Federal Soil Protection Act. Metal concentrations generally peak at depths of 0.2 to 0.7 m below the floodplain surface and are assumed to represent the period of maximum metal releases to the environment through upstream industrial activity, ore mining, or both. In eight of the cores, radiocarbon ages obtained below the depth of peak metal concentrations provide maximum dates for sediment accumulation of between 90 and 1700 years ago, with most ages clustering in the period of 90 to 300 years ago. The ages and depth to peak metal concentrations indicate 0.6 to 1.0 m of floodplain sedimentation over the last 150 to 300 years (0.3-0.4 cm y- 1), which exceed sedimentation amounts and rates found in surrounding watersheds. Surface sediments contain lower metal concentrations, suggesting deposition recently of cleaner sediments. Trace metals stored along the Dill River serve as a reminder that stores of contaminants exist in geomorphically sensitive locations of the fluvial system. These legacy sediments bear the chemical imprint of industrial or mining activities that no longer occur in the watershed.

  15. Edge effects are important in supporting beetle biodiversity in a gravel-bed river floodplain.

    PubMed

    Langhans, Simone D; Tockner, Klement

    2014-01-01

    Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60-100 m, and 5 m within the riparian forest), and time of the year (February-November) across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy), to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment-groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern) that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct--yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity. PMID:25545280

  16. Edge Effects Are Important in Supporting Beetle Biodiversity in a Gravel-Bed River Floodplain

    PubMed Central

    Langhans, Simone D.; Tockner, Klement

    2014-01-01

    Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60–100 m, and 5 m within the riparian forest), and time of the year (February–November) across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy), to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment-groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern) that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct – yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity. PMID:25545280

  17. Edge effects are important in supporting beetle biodiversity in a gravel-bed river floodplain.

    PubMed

    Langhans, Simone D; Tockner, Klement

    2014-01-01

    Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60-100 m, and 5 m within the riparian forest), and time of the year (February-November) across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy), to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment-groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern) that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct--yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity.

  18. Role of active floodplains for nutrient retention in the river Rhine.

    PubMed

    Olde Venterink, H; Wiegman, F; Van der Lee, G E M; Vermaat, J E

    2003-01-01

    We evaluated the importance of floodplains for nutrient retention in two distributaries of the river Rhine (Waal and IJssel) by monitoring N and P retention in a body of water during downstream transport. We hypothesized that (i) retention of P is much larger than retention of N and (ii) nutrient retention increases with an increasing amount of the discharge flowing through floodplains (QF). The second hypothesis was tested by comparing retention between the rivers Waal (low QF) and IJssel (high QF), as well as at different discharges. Total nitrogen (TN) did not decrease significantly during downstream transport in both rivers, whereas 20 to 45% of total phosphorus (TP) disappeared during transport in the river IJssel. This difference between N and P retention-supporting the first hypothesis-was probably caused by differences in sedimentation through a much lower proportion of N adsorbed to particles than of P (2-3% of N vs. 50-70% of P). Phosphorus retention was only observed in the IJssel and not in the Waal, and absolute P retention (g P s(-1) km(-1)) in the IJssel increased with increasing QF. The second hypothesis was, nevertheless, not fully supported, because the percentage P retention (% of P load) decreased (instead of increased) with increasing QF. The percentage P retention increased with decreasing river depth and flow velocity; it seemed related to the efficiency of sediment trapping.

  19. Rates and spatial patterns of sediment dispersal across the lower Strickland River floodplain, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Swanson, K. M.; Apte, S.; Aalto, R.; Marshall, A.; Dietrich, W.

    2004-12-01

    As part of a NSF Margins Source to sink study, we are exploring the rates and patterns of floodplain sediment vertical accretion on the Middle Fly River and the lower Strickland River, Papua New Guinea. The rivers join at 6 m above sea level where tidal influences are currently weak (except at exceptionally low flow). In response to post-glacial sea level rise both rivers aggraded, but the Strickland, carrying 7 times the sediment load, twice the discharge, and transiting through a much shorter lowland reach, has built a roughly 10 times steeper slope and a much coarser bed than the Fly. We have hypothesized that as a consequence of this difference the rate of sediment loss to the floodplain will be much lower than on the Fly (which is currently about 40% for the Middle Fly Reach). Near the gravel-sand transition, the Strickland floodplain rapidly widens downstream to an average width of approximately 10 km, and the channel has built an elevated meander belt across the roughly 100 km long plain. Recently, sediment laden flood flows have occasionally spilled out of the Strickland through an oxbow and traveled along a small channel into Lake Murray. Lake Murray is directly connected to the Strickland via the Herbert River, a large, deep channel that occasionally reverses and directs Strickland waters to the Lake. To document the spatial pattern of sediment deposition, sediment cores were collected at 11 transects across the floodplain. In addition, samples were collected along the outflow channel, in Lake Murray, and in a separate oxbow fed only by a tie channel. Duplicates and, in places, triplicate core samples were taken to enable independent analysis of sedimentation rates using two methods. Mine tailings introduced into the headwaters of the Strickland since 1990, although of relatively minor importance to the total load of the lower Strickland; provide a distinct elevated Pb and Ag signature in the recently deposited sediment. In over 30 cores, 210Pb analyses

  20. Breeding bird assemblages associated with stages of forest succession in large river floodplains

    USGS Publications Warehouse

    Knutson, M.G.; McColl, L.E.; Suarez, S.A.

    2005-01-01

    Floodplain forests rival all other habitat types in bird density and diversity. However, major successional changes are predicted for floodplain forests along the Mississippi River in the coming decades; young forests may replace the existing mature silver maple (Acer saccharinum L.) forests in some areas. We wanted to assess how the breeding bird community might respond to these changes. We studied stands of young forests along the middle Mississippi River, comparing the breeding bird assemblages among three stages of forest succession: shrub/scrub, young cottonwood (Populus deltoides Marshall) and willow (Salix nigra Marshall) forests, and mature silver maple dominated forests. We recorded a total of 54 bird species; the most frequently observed species were the indigo bunting (Passerina cyanea), red-winged blackbird (Agelaius phoeniceus), and yellow-billed cuckoo (Coccyzus americanus). Bird species richness differed among the habitat types, with mature forests supporting the largest number of species and the most species of management concern. The shrub/scrub and mature forest bird assemblages were distinct and shared few species, but the young forests had no identifiable bird species assemblage, sharing species found in both of the other habitat types. The bird assemblages we observed in young forests may become more prevalent as aging floodplain forests are replaced with younger stages of forest succession. Under this scenario, we would expect a temporary local decrease in bird species richness and habitat for species of management concern.

  1. Role of Fish as Predators of Mosquito Larvae on the Floodplain of the Gambia River

    PubMed Central

    LOUCA, VASILIS; LUCAS, MARTYN C.; GREEN, CLARE; MAJAMBERE, SILAS; FILLINGER, ULRIKE; LINDSAY, STEVE W.

    2009-01-01

    We examined the potential of using native fish species in regulating mosquitoes in the floodplain of the Gambia River, the major source of mosquitoes in rural parts of The Gambia. Fishes and mosquito larvae were sampled along two 2.3-km-long transects, from the landward edge of the floodplain to the river from May to November 2005 to 2007. A semifield trial was used to test the predatory capacity of fish on mosquito larvae and the influence of fish chemical cues on oviposition. In the field, there was less chance of finding culicine larvae where Tilapia guineensis, the most common floodplain fish, were present; however, the presence of anophelines was not related to the presence or absence of any fish species. In semifield trials, both T. guineensis and Epiplatys spilargyreius were effective predators, removing all late-stage culicine and anopheline larvae within 1 d. Fewer culicines oviposited in sites with fish, suggesting that ovipositing culicine females avoid water with fish. In contrast, oviposition by anophelines was unaffected by fish. Our studies show that T. guineensis is a potential candidate for controlling mosquitoes in The Gambia. PMID:19496426

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

    USGS Publications Warehouse

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

    2015-01-01

    As 10.5 million t (7.1 million m3) of sediment was released from two former reservoirs, downstream dispersion of a sediment wave caused widespread bed aggradation of ~ 1 m (greater where pools filled), changed the river from pool–riffle to braided morphology, and decreased the slope of the lowermost river. The newly deposited sediment, which was finer than most of the pre-dam-removal bed, formed new bars (largely pebble, granule, and sand material), prompting aggradational channel avulsion that increased the channel braiding index by almost 50%. As a result of mainstem bed aggradation, floodplain channels received flow and accumulated new sediment even during low to moderate flow conditions. The river system showed a two- to tenfold greater geomorphic response to dam removal (in terms of bed elevation change magnitude) than it had to a 40-year flood event four years before dam removal. Two years after dam removal began, as the river had started to incise through deposits of the initial sediment wave, ~ 1.2 million t of new sediment (~ 10% of the amount released from the two reservoirs) was stored along 18 river km of the mainstem channel and 25 km of floodplain channels. The Elwha River thus was able to transport most of the released sediment to the river mouth. The geomorphic alterations and changing bed sediment grain size along the Elwha River have important ecological implications, affecting aquatic habitat structure, benthic fauna, salmonid fish spawning and rearing potential, and riparian vegetation. The response of the river to dam removal represents a unique opportunity to observe and quantify fundamental geomorphic processes associated with a massive sediment influx, and also provides important lessons for future river-restoration endeavors.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  5. Large-Scale Dam Removal on the Elwha River, Washington, USA: River Channel and Floodplain Geomorphic Change

    NASA Astrophysics Data System (ADS)

    East, A. E.; Pess, G. R.; Bountry, J.; Magirl, C. S.; Ritchie, A. C.; Logan, J. B.; Randle, T. J.; Mastin, M. C.; Duda, J.; Liermann, M. C.; McHenry, M. L.; Beechie, T. J.; Shafroth, P. B.

    2014-12-01

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

  6. The significance of sediment contamination in the Elbe River floodplain (Czech Republic)

    NASA Astrophysics Data System (ADS)

    Chalupová, Dagmar; Janský, Bohumír; Langhammer, Jakub; Šobr, Miroslav; Jiři, Medek; Král, Stanislav; Jiřinec, Petr; Kaiglova, Jana; Černý, Michal; Žáček, Miroslav; Leontovyčova, Drahomíra; Halířová, Jarmila

    2015-04-01

    The abstract brings the information about the research that was focused on anthropogenic pollution of river and lake sediments in the middle course of the Elbe River (Czech Republic). The main aim was to identify and to evaluate the significance of old polluted sediments in the river and its side structures (old meanders, cut lakes, oxbow lakes) between Hradec Králové and Mělník (confluence with the Moldau River) and to assess the risk coming from the remobilization of the contaminated matter. The Elbe River floodplain has been highly inhabited since the Middle Ages, and, especially in the 20th century, major industrial plants were founded here. Since that time, the anthropogenic load of the river and it`s floodplain has grown. Although the contaminants bound to the sediment particles are usually stable, the main risk is coming from the fact that under changes in hydrological regime and water quality (floods, changes in pH, redox-potential, presence of complex substances etc.), the pollution can be released and remobilized again. The most endangered areas are: the surroundings of Pardubice (chemical factory Synthesia, Inc.; refinery PARAMO), and Neratovice (chemical factory Spolana, Inc.). The chemical factories situated close to these towns represented the most problematic polluters of the Elbe River especially during 2nd half of 20th century. In the research, the main attention was aimed at subaquatic sediments of selected cut lakes situated in the vicinity of the above mentioned sources of pollution. To describe the outreach of contamination, several further fluvial lakes were taken into account too. Sediment sampling was carried out from boats on lakes and with the help of drilling rig in the floodplain. Gained sediment cores were divided into several parts which were analysed separately. Chemical analyses included substances identified by ICPER (International Commission for the Protection of the Elbe River) as well as chemicals considered as significant in

  7. Channelization and floodplain forests: Impacts of accelerated sedimentation and valley plug formation on floodplain forests of the Middle Fork Forked Deer River, Tennessee, USA

    USGS Publications Warehouse

    Oswalt, S.N.; King, S.L.

    2005-01-01

    We evaluated the severe degradation of floodplain habitats resulting from channelization and concomitant excessive coarse sedimentation on the Middle Fork Forked Deer River in west Tennessee from 2000 to 2003. Land use practices have resulted in excessive sediment in the tributaries and river system eventually resulting in sand deposition on the floodplain, increased overbank flooding, a rise in the groundwater table, and ponding of upstream timber. Our objectives were to: (1) determine the composition of floodplain vegetation communities along the degraded river reach, (2) to isolate relationships among these communities, geomorphic features, and environmental variables and (3) evaluate successional changes based on current stand conditions. Vegetation communities were not specifically associated with predefined geomorphic features; nevertheless, hydrologic and geomorphic processes as a result of channelization have clearly affected vegetation communities. The presence of valley plugs and continued degradation of upstream reaches and tributaries on the impacted study reach has arrested recovery of floodplain plant communities. Historically common species like Liquidambar styraciflua L. and Quercus spp. L. were not important, with importance values (IV) less than 1, and occurred in less than 20% of forested plots, while Acer rubrum L., a disturbance-tolerant species, was the most important species on the site (IV = 78.1) and occurred in 87% of forested plots. The results of this study also indicate that channelization impacts on the Middle Fork Forked Deer River are more temporally and spatially complex than previously described for other river systems. Rehabilitation of this system necessitates a long-term, landscape-scale solution that addresses watershed rehabilitation in a spatially and temporally hierarchical manner. ?? 2005 Elsevier B.V. All rights reserved.

  8. Metals and arsenic in soils and corresponding vegetation at Central Elbe river floodplains (Germany).

    PubMed

    Overesch, M; Rinklebe, J; Broll, G; Neue, H-U

    2007-02-01

    Floodplain soils at the Elbe river are frequently polluted with metals and arsenic. High contents of these pollutants were detected down to subsoil layers. NH4NO3-extractable (phytoavailable) Cd, Ni, and Zn were elevated in horizons with high acidity. Among five common floodplain plant species, Artemisia vulgaris showed highest concentrations of Cd, Cu, and Hg, Alopecurus pratensis of As and Phalaris arundinacea of Ni, Pb, and Zn. Relationships were weak between metal concentrations in plants and phytoavailable stocks in soil. As and Hg uptake seems to be enhanced on long submerged soils. Enrichments of Cd and Hg are linked to a special plant community composition. Grassland herbage sampled in July/August revealed higher concentrations of As (+122%), Hg (+124%), and Pb (+3723%) than in May. To limit harmful transfers into the food chain, low-lying terraces and flood channels revealing highest contaminations or phytoavailabilities should be excluded from mowing and grazing.

  9. Comparing riparian forest processes on large rivers to inform floodplain management and restoration

    NASA Astrophysics Data System (ADS)

    Stella, J. C.; Piegay, H.; Gruel, C.; Riddle, J.; Raepple, B.

    2014-12-01

    In populous, water-limited regions, humans have profoundly altered the river and floodplain environment to satisfy society's demands for water, power, navigation and safety. River management also profoundly alters riparian forests, which respond to changes in disturbance regimes and sediment dynamics. In this study, we compare forest and floodplain development along two of the most heavily modified rivers in mediterranean-climate regions, the middle Sacramento (California, USA) and the lower Rhône (SE France). The Sacramento was dammed in 1942 and is now managed for irrigation, hydropower and flood control. The Rhône channel was engineered for navigation prior to 1900, and since then has been dammed and diverted at 18 sites for hydropower and irrigation. We conducted extensive forest inventories and sampled fine sediment depth in regulated reaches within both systems, and compared pre- versus post-dam patterns of deposition and linked forest development. We sampled 441 plots (500 m2 each) along 160 km of the Sacramento, and 88 plots (1256 m2) stratified by management epoch (pre-river engineering, pre-dam, post-dam) along 160 km of the Rhône. On the Sacramento, forest composition showed shifting tree species dominance across a chronosequence of aerial photo dates over 110 years. The transition from willow to cottonwood (Populus) occurred within 20 years, and the transition to mixed forest started after 50-60 years. On the Rhône, the pre- versus post-dam surfaces at each site had distinct geomorphic and floristic characteristics. Floodplain areas that emerged and were forested in the pre-dam period were at higher elevation, and supported 30-50% more basal area, 20-30% more vine cover, and greater plant species diversity than those that emerged in the post-dam period. The shift from Populus dominance to other species began approximately a decade earlier on the Rhône compared to the Sacramento. Both rivers showed a strong understory presence on young floodplains

  10. Habitat associations, reproduction and diet of the Guinean tilapia Tilapia guineensis of the Gambia River floodplains.

    PubMed

    Louca, V; Lindsay, S W; Piyapong, C; Lucas, M C

    2010-06-01

    The ecology of the Guinean tilapia Tilapia guineensis a dominant species of the lower Gambia River floodplains and an important food source in parts of West Africa was studied to better understand the threat posed from construction of a barrage across the river. The catch per unit effort (CPUE) of T. guineensis was positively associated with conductivity and dissolved oxygen and negatively associated with water depth and the % vegetation cover. Diet studies indicated that the T. guineensis is primarily an iliophage. The peak of reproduction was at the beginning of the rainy season. CPUE peaked in May, just before the first rains, and subsequently declined, probably reflecting movement into newly flooded habitat. Median size at maturity was 11.6 cm total length, L(T), for females and 12.5 cm L(T) for males. L(T)-frequency analysis indicated several juvenile cohorts as well as very young fish on the floodplains each month, suggesting continuation of reproduction throughout the rainy season. The impending construction of a hydroelectric dam on the Gambia River is likely to affect T. guineensis negatively through anticipated changes in the hydrology of the river.

  11. Habitat associations, reproduction and diet of the Guinean tilapia Tilapia guineensis of the Gambia River floodplains.

    PubMed

    Louca, V; Lindsay, S W; Piyapong, C; Lucas, M C

    2010-06-01

    The ecology of the Guinean tilapia Tilapia guineensis a dominant species of the lower Gambia River floodplains and an important food source in parts of West Africa was studied to better understand the threat posed from construction of a barrage across the river. The catch per unit effort (CPUE) of T. guineensis was positively associated with conductivity and dissolved oxygen and negatively associated with water depth and the % vegetation cover. Diet studies indicated that the T. guineensis is primarily an iliophage. The peak of reproduction was at the beginning of the rainy season. CPUE peaked in May, just before the first rains, and subsequently declined, probably reflecting movement into newly flooded habitat. Median size at maturity was 11.6 cm total length, L(T), for females and 12.5 cm L(T) for males. L(T)-frequency analysis indicated several juvenile cohorts as well as very young fish on the floodplains each month, suggesting continuation of reproduction throughout the rainy season. The impending construction of a hydroelectric dam on the Gambia River is likely to affect T. guineensis negatively through anticipated changes in the hydrology of the river. PMID:20557603

  12. Influence of wood and forests on fish abundance and richness in a large floodplain river

    NASA Astrophysics Data System (ADS)

    Gregory, S.; Wildman, R. C.

    2005-05-01

    We investigated the influence of large wood and adjacent floodplain forests on fish assemblages along the 230-km mainstem of the Willamette River, Oregon. Fish were sampled in open reaches using boat electroshocking, beach seining, and backpack electroshocking in paired sites with intact forest and land converted to agriculture or urban use. Fish abundance and richness were statistically significantly greater in reaches with intact forest. We observed that wood abundance in the river was related to density of trees along the floodplain margin and developed an intensive sampling approach for determining fish abundance and richness in accumulations of large wood in the river. Fish were sampled from "wood corrals" and marked by fin clipping. These sites were sampled the following day to determine the abundances of each species by mark-recapture. Nets were placed around similar areas in adjacent habitats without wood. Fish numbers around wood accumulations were more than double those in areas without wood. The number of fish species was greater by an average of four species in sites with wood. These results were used to project the consequence of historical changes in fish abundance and richness in the Willamette River and forecast possible responses to future land use change.

  13. Molecular characterization of the species Salvinia (Salviniaceae) from the upper Paraná River floodplain.

    PubMed

    Machado, S A; Oliveira, A V; Fabrin, T M C; Prioli, S M A P; Prioli, A J

    2016-08-12

    The pteridophytes Salvinia minima, S. herzogii, and S. auriculata are among the most abundant aquatic macrophytes in the upper Paraná River floodplain. Since some species have highly similar morphological features, it is very difficult to identify members of this genus to the species level. An indication of this difficulty is a set of poorly differentiated taxa comprising S. auriculata and S. herzogii known as the 'S. auriculata complex', which is found in the Paraná River together with other Salvinia species such as S. biloba and S. molesta. Some authors have reported the existence of inter-species hybrids. Despite the complex Salvinia taxonomy, few genetic studies have been performed on purported species within the genus to resolve this complexity. The present study was conducted to determine useful molecular sequences for the discrimination of Salvinia species of the upper Paraná River floodplain. Molecular data were compared with data of other species of the genus to clarify phylogenetic relationships, employing the nucleotide sequence trnL-trnF from the chloroplast DNA. The results revealed that Salvinia populations in the upper Paraná River floodplain belong to different species and indicated that species of the S. auriculata complex may be distinguished from one another after the division of the S. minima group, corroborating results by other researchers. Although the taxonomic position of S. oblongifolia was clarified, as high closeness between S. oblongifolia and the S. auriculata complex was reported, Salvinia kinship is still not thoroughly established and further investigations in morphology and molecular diversity are required.

  14. CHANGES IN LOWLAND FLOODPLAIN SEDIMENTATION PROCESSES: PRE-DISTURBANCE TO POST-REHABILITATION, COSUMNES RIVER, CA. (R825433)

    EPA Science Inventory

    During the late Holocene, sediment deposition on the lowland Cosumnes River floodplain, CA has depended on factors that varied temporally and spatially, such as basin subsidence, sea level rise, flow, and sediment supply from both the Sacramento River system and from the Cosum...

  15. The influence of river regulation and land use on floodplain forest regeneration in the semi-arid upper Colorado River Basin, USA

    USGS Publications Warehouse

    Northcott, K.; Andersen, D.C.; Cooper, D.J.

    2007-01-01

    Flow regulation effects on floodplain forests in the semi-arid western United States are moderately well understood, whereas effects associated with changes in floodplain land use are poorly documented. We mapped land cover patterns from recent aerial photos and applied a classification scheme to mainstem alluvial floodplains in 10 subjectively selected 4th order hydrologic units (subbasins) in the Upper Colorado River Basin (UCRB) in order to document land use patterns (floodplain development) and assess their effects on Fremont cottonwood forest (CF) regeneration. Three of the mainstem rivers were unregulated, five were moderately regulated and two were highly regulated. We classified polygons as Undeveloped (with two categories, including CF) and Developed (with five categories). We ground-truthed 501 randomly selected polygons (4-28% of the floodplain area in each subbasin) to verify classification accuracy and to search for cottonwood regeneration, defined as stands established since regulation began or 1950, whichever is most recent. From 40% to 95% of the floodplain area remained undeveloped, but only 19-70% of the floodplain area was classified as forest. Regeneration occupied a mean of 5% (range 1-17%) of the floodplain. The likelihood of the presence of regeneration in a polygon was reduced 65% by development and independently in a complex manner by flow regulation. Our analyses indicate that floodplain forests may be in jeopardy on both regulated and unregulated rivers and that information on historical forest extent is needed to better understand their current status in the UCRB. Conservation efforts need to be coordinated at a regional level and address the potentially adverse affects of both flow regulation and floodplain development.

  16. Biodiversity of zooplankton communities in the Upper Paraná River floodplain: interannual variation from long-term studies.

    PubMed

    Lansac-Tôha, F A; Bonecker, C C; Velho, L F M; Simões, N R; Dias, J D; Alves, G M; Takahashi, E M

    2009-06-01

    We investigated the effect of interannual variation of hydrosedimentological regime and connectivity on the zooplankton biodiversity in the Upper Paraná River floodplain. Zooplankton samplings were undertaken between 2000 and 2007, in different environments of the floodplain, including connected and isolated floodplain lakes, backwaters, rivers and channels. The zooplankton included 541 species. Rotifers showed the highest species richness and abundance. Among the zooplankton species, 71 represent new occurrence records for the floodplain. The species accumulation curve showed a continuous increase in gamma diversity, demonstrating the importance of long-term research for accurate knowledge of biodiversity in heterogeneous and dynamic ecosystems, such as the floodplains. Interannual beta diversity among studied years indicated a lesser alteration in community composition in 2001, when a long limnophase period was observed. In most of the environments, the highest species richness values were related to the greatest flooding amplitudes. Flooding amplitude, which is associated with connectivity, favors faunal exchange amongst the environments and between the pelagic and littoral zones. This explains the occurrence of both planktonic and non-planktonic species within the community. On the other hand, mean zooplankton abundance values were higher when a long isolation period occurred. Differences between the potamophase and limnophase amplitude associated with connectivity among the environments were the most important factors for the structure and dynamics of the zooplankton community in the Upper Paraná River floodplain.

  17. Forty years of vegetation change on the Missouri River Floodplain

    USGS Publications Warehouse

    Johnson, W.C.; Dixon, M.D.; Scott, M.L.; Rabbe, L.; Larson, G.; Volke, M.; Werner, B.

    2012-01-01

    Comparative inventories in 1969 and 1970 and in 2008 of vegetation from 30 forest stands downstream of Garrison Dam on the Missouri River in central North Dakota showed (a) a sharp decline in Cottonwood regeneration; (b) a strong compositional shift toward dominance by green ash; and (c) large increases in invasive understory species, such as smooth brome, reed canary grass, and Canada thistle. These changes, and others discovered during remeasurement, have been caused by a complex of factors, some related to damming (altered hydrologic and sediment regimes, delta formation, and associated wetdry cycles) and some not (diseases and expansion of invasive plants). Dominance of green ash, however, may be short lived, given the likelihood that the emerald ash borer will arrive in the Dakotas in 510 years, with potentially devastating effects. The prospects for recovery of this valuable ecosystem, rich in ecosystem goods and services and in American history, are daunting. ?? 2012 by American Institute of Biological Sciences. All rights reserved.

  18. Forty years of vegetation change on the Missouri River floodplain

    USGS Publications Warehouse

    Johnson, W. Carter; Dixon, Mark D.; Scott, Michael L.; Rabbe, Lisa; Larson, Gary; Volke, Malia; Werner, Brett

    2012-01-01

    Comparative inventories in 1969 and 1970 and in 2008 of vegetation from 30 forest stands downstream of Garrison Dam on the Missouri River in central North Dakota showed (a) a sharp decline in Cottonwood regeneration; (b) a strong compositional shift toward dominance by green ash; and (c) large increases in invasive understory species, such as smooth brome, reed canary grass, and Canada thistle. These changes, and others discovered during remeasurement, have been caused by a complex of factors, some related to damming (altered hydrologic and sediment regimes, delta formation, and associated wet-dry cycles) and some not (diseases and expansion of invasive plants). Dominance of green ash, however, may be short lived, given the likelihood that the emerald ash borer will arrive in the Dakotas in 5-10 years, with potentially devastating effects. The prospects for recovery of this valuable ecosystem, rich in ecosystem goods and services and in American history, are daunting.

  19. The risk of river pollution due to washout from contaminated floodplain water bodies during high floods

    NASA Astrophysics Data System (ADS)

    Lyubimova, Tatyana; Lepikhin, Anatoly; Parshakova, Yanina; Tiunov, Alexey

    2016-04-01

    Today, the potential impact of extremely high floods, which in the last years have become a rather frequent weather-related disaster, is the problem of primary concern. In studies of the potential impact of floods the emphasis is placed first of all on the estimation of possible flood zones and the analysis of the flow regimes in these zones. However, in some cases the hydrochemical parameters related to changes in the chemical composition of water are more important than the hydraulic parameters. It is generally believed that the higher is the flow rate, the more intensive is the process of dissolution, i.e. the lower is the concentration of limiting contaminants in water. However, this statement is valid provided that flooding does not activate new sources of water pollution such as contaminated floodplain water bodies located in the vicinity of water supply systems. Being quite reliable and safe at small and moderate discharges, in the case of extremely high level of river waters they become intensive sources of water pollution, essentially limiting the water consumption schedule for downstream water consumers. It should be noted that compared to the well-studied mechanisms of waste discharge due to failure of hydraulic engineering structures by flood waves, the mechanisms of pollutant washout from the contaminated floodplain water bodies by the flood waves is still poorly understood. We analyze the impacts of such weather-related events on the quality of water in the water intake system, taking as an example, the section of the Vyatka River located in the Prikamskaya lowland of the Russian Federation. The risk of river pollution due to washout from the contaminated floodplain water bodies during high floods is studied by hydrodynamical modeling in the framework of combined approach using one-, two- and three-dimensional hydrodynamic models are implemented and by in situ measurements. It is shown that during high floods the removal of pollutants from the

  20. Effects of Reduced Summer Precipitation on Productivity and Forage Quality of Floodplain Meadows at the Elbe and the Rhine River

    PubMed Central

    Ludewig, Kristin; Donath, Tobias W.; Zelle, Bianka; Eckstein, R. Lutz; Mosner, Eva; Otte, Annette; Jensen, Kai

    2015-01-01

    Background Floodplain meadows along rivers are semi-natural habitats and depend on regular land use. When used non-intensively, they offer suitable habitats for many plant species including rare ones. Floodplains are hydrologically dynamic ecosystems with both periods of flooding and of dry conditions. In German floodplains, dry periods may increase due to reduced summer precipitation as projected by climate change scenarios. Against this background, the question arises, how the forage quantity and quality of these meadows might change in future. Methods We report results of two field trials that investigated effects of experimentally reduced summer precipitation on hay quantity and quality of floodplain meadows at the Rhine River (2011-2012) and at two Elbe tributaries (2009-2011). We measured annual yield, the amount of hay biomass, and contents of crude protein, crude fibre, energy, fructan, nitrogen, phosphorus, and potassium. Results The annual yield decreased under precipitation reduction at the Rhine River. This was due to reduced productivity in the second cut hay at the Rhine River in which, interestingly, the contents of nitrogen and crude protein increased. The first cut at the Rhine River was unaffected by the treatments. At the Elbe tributaries, the annual yield and the hay quantity and quality of both cuts were only marginally affected by the treatments. Conclusion We conclude that the yield of floodplain meadows may become less reliable in future since the annual yield decreased under precipitation reduction at the Rhine River. However, the first and agriculturally more important cut was almost unaffected by the precipitation reduction, which is probably due to sufficient soil moisture from winter/spring. As long as future water levels of the rivers will not decrease during spring, at least the use of the hay from the first cut of floodplain meadows appears reliable under climate change. PMID:25950730

  1. Assessment of groundwater input and water quality changes impacting natural vegetation in the Loxahatchee River and floodplain ecosystem, Florida

    USGS Publications Warehouse

    Orem, William H.; Swarzenski, Peter W.; McPherson, Benjamin F.; Hedgepath, Marion; Lerch, Harry E.; Reich, Christopher; Torres, Arturo E.; Corum, Margo D.; Roberts, Richard E.

    2007-01-01

    The Loxahatchee River and Estuary are small, shallow, water bodies located in southeastern Florida. Historically, the Northwest Branch (Fork) of the Loxahatchee River was primarily a freshwater system. In 1947, the river inlet at Jupiter was dredged for navigation and has remained permanently open since that time. Drainage patterns within the basin have also been altered significantly due to land development, road construction (e.g., Florida Turnpike), and construction of the C-18 and other canals. These anthropogenic activities along with sea level rise have resulted in significant adverse impacts on the ecosystem over the last several decades, including increased saltwater encroachment and undesired vegetation changes in the floodplain. The problem of saltwater intrusion and vegetation degradation in the Loxahatchee River may be partly induced by diminished freshwater input, from both surface water and ground water into the River system. The overall objective of this project was to assess the seasonal surface water and groundwater interaction and the influence of the biogeochemical characteristics of shallow groundwater and porewater on vegetation health in the Loxahatchee floodplain. The hypothesis tested are: (1) groundwater influx constitutes a significant component of the overall flow of water into the Loxahatchee River; (2) salinity and other chemical constituents in shallow groundwater and porewater of the river floodplain may affect the distribution and health of the floodplain vegetation.

  2. Mobilization of Floodplain Sediments by Chute Cutoffs on a Large River: Lower Wabash River, Illinois-Indiana

    NASA Astrophysics Data System (ADS)

    Zinger, J. A.; Rhoads, B. L.; Best, J.; Engel, F.; Konsoer, K. M.

    2010-12-01

    Bend cutoffs are a common mechanism of morphologic change in all scales of meandering rivers worldwide. Cutoffs can develop either by progressive migration of an elongated bend onto itself, forming a neck cutoff, or by erosion of a new channel across the neck of a bend, producing a chute cutoff. In contrast to the slow processes of “shaving” of the floodplain by outer bank erosion or formation of neck cutoffs by lateral channel migration, the sudden development of a chute cutoff channel can rapidly introduce a large volume of floodplain sediment into the downstream river channel. Formation of a chute cutoff channel also occurs on much shorter timescales than infilling of the subsequent oxbow lake. The asynchronous nature of such floodplain sediment release and storage resulting from cutoffs has important implications for longer-term floodplain sediment balance and the accurate modeling of floodplain evolution and architecture. In this study, using aerial photography and ground survey, we quantified the quantity of floodplain sediment mobilized by two chute cutoff events on Mackey Bend, a large, elongated meander of the lower Wabash River, IL-IN, located just upstream of the Ohio River confluence. A chute cutoff channel on this bend developed during flooding in June 2008 and was followed by formation of a second cutoff channel in July 2009. Here, we compare the volume of sediment released by these cutoff events to the background flux of sediment generated by lateral migration of the bend in the previous 78 years. Our study also explores the influence of these cutoff events on the morphology of the Wabash-Ohio confluence immediately downstream of the evolving chute cutoff channels. We found that, in just over two years, these cutoffs released c. 3. 6 million cubic meters of floodplain sediment, which is comparable to 4.6% of the annual sediment load of the Mississippi River. According to our calculations, it would take over 60 years of lateral migration of Mackey

  3. Plant water status relationships among major floodplain sites of the Flathead River, Montana

    USGS Publications Warehouse

    Lee, L.C.; Hinckley, T.M.; Scott, M.L.

    1985-01-01

    Water status measurements of dominant species from major floodplain plant community types of the North Fork Flathead River, Montana were used to test the accuracy of site moisture gradient relationships postulated from floristic ordinations and site water balance estimates. Analysis of variance tests showed significant differences among the average predawn xylem pressure potential (ψp) of species in several community types. However, additional analyses failed to indicate a significant degree of association between averaged predawn Yp measurements and either floristic ordination or site water balance results. Sixty eight percent of 22 trials comparing the diurnal average ψp of the same species in different community types on the same day were less negative for a species in the wetter community types as predicted by floristic ordinations. Similarly, 64% of the trials indicated that the diurnal average stomatal conductance was higher for a species in the wetter type. These results suggest that although a floodplain moisture gradient exists, it alone does not limit the distribution of floodplain plant communities in the North Fork.

  4. Floodplain geomorphic processes and environmental impacts of human alteration along coastal plain rivers, USA

    USGS Publications Warehouse

    Hupp, C.R.; Pierce, A.R.; Noe, G.B.

    2009-01-01

    Human alterations along stream channels and within catchments have affected fluvial geomorphic processes worldwide. Typically these alterations reduce the ecosystem services that functioning floodplains provide; in this paper we are concerned with the sediment and associated material trapping service. Similarly, these alterations may negatively impact the natural ecology of floodplains through reductions in suitable habitats, biodiversity, and nutrient cycling. Dams, stream channelization, and levee/canal construction are common human alterations along Coastal Plain fluvial systems. We use three case studies to illustrate these alterations and their impacts on floodplain geomorphic and ecological processes. They include: 1) dams along the lower Roanoke River, North Carolina, 2) stream channelization in west Tennessee, and 3) multiple impacts including canal and artificial levee construction in the central Atchafalaya Basin, Louisiana. Human alterations typically shift affected streams away from natural dynamic equilibrium where net sediment deposition is, approximately, in balance with net erosion. Identification and understanding of critical fluvial parameters (e.g., stream gradient, grain-size, and hydrography) and spatial and temporal sediment deposition/erosion process trajectories should facilitate management efforts to retain and/or regain important ecosystem services. ?? 2009, The Society of Wetland Scientists.

  5. Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere

    NASA Technical Reports Server (NTRS)

    Devol, Allan H.; Richey, Jeffrey E.; Forsberg, Bruce R.; Martinelli, Luiz A.

    1990-01-01

    Methane fluxes to the troposphere from the three principal habitats of the floodplain of the Amazon River main stem (open waters, emergent macrophyte beds, and flooded forests) were determined along a 1700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 mg CH4/sq m per day and were significantly lower than similar emissions determined previously for the high-water period, 184 mg CH4/sq m per day (July-August 1986). This difference was due to significantly lower emissions from floating macrophyte environments. Low-water emissions from open waters and flooded forest areas were not significantly different than at high water. A monthly time series of methane emission from eight lakes located in the central Amazon basis showed similar results. The data were used to calculate a seasonally weighted annual emission to the troposphere from the Amazon River main stem floodplain of 5.1 Tg/yr, which indicates the importance of the area in global atmospheric chemistry.

  6. Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere

    SciTech Connect

    Devol, A.H.; Richey, J.E. ); Forsberg, B.R. ); Martinelli, L.A. )

    1990-09-20

    Methane fluxes to the troposphere from the three principal habitats of the floodplain of the Amazon River main stem (open waters, emergent macrophyte beds, and flooded forests) were determined along a 1,700-km reach of the river during the low-water period of the annual flood cycle (November-December 1988). Overall, emissions averaged 68 ({plus minus} 20) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1} and were significantly lower than similar emissions determined previously for the high-water period, 184 ({plus minus} 41) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1} (July-August 1986). This difference was due to significantly lower emissions from floating macrophyte environments. Low-water emissions from open waters and flooded forest areas were not significantly different than at high water. A monthly time series of methane emissions from eight lakes located in the central Amazon basin showed similar results. Average annual emission from the lakes was 125 ({plus minus} 28) mg CH{sub 4} m{sup {minus}2} d{sup {minus}1}. Methane emissions from lakes were significantly higher during the high water period, again primarily due to an increase in emissions from macrophyte habitats. The data were used to calculate a seasonally weighted annual emission to the troposphere from the Amazon River main stem floodplain of 5.1 Tg yr{sup {minus}1}, which indicates the importance of the area in global atmospheric chemistry.

  7. Water balance of selected floodplain lake basins in the Middle Bug River valley

    NASA Astrophysics Data System (ADS)

    Dawidek, J.; Ferencz, B.

    2013-08-01

    This study is the first attempt in the literature on the subject of comparing water balance equations for floodplain lake basins depending on the type of connection the lake has to its parent river. Where confluent lakes (upstream connections) were concerned, it was only possible to apply a classic water balance equation. When dealing with contrafluent lakes (downstream connections) as well as lakes with a complex recharge type (contrafluent-confluent) modified equations were created. The hydrological type of a lake is decided by high water flow conditions and, consequently, the duration of potamophase (connection with a river) and limnophase (the isolation of the lake), which determine the values of particular components and the proportion of the vertical to horizontal water exchange rate. Confluent lakes are characterised by the highest proportion of horizontal components (the inflow and runoff of river water) to the vertical ones (precipitation and evaporation). The smallest differences occur with respect to a contrafluent lake. In the case of confluent lakes, the relationship between water balance components resulted from the consequent water flow through the basin, consistent with the slope of the river channel and valley. The supplying channels of contrafluent lakes had an obsequent character, which is why the flow rate was lower. Lakes with a complex, contrafluent-confluent recharge type showed intermediate features. After a period of slow contrafluent recharge, the inflow of water through a downstream crevasse from the area of the headwater of the river was activated; this caused a radical change of flow conditions into confluent ones. The conditions of water retention in lake basins were also varied. Apart from hydrological recharge, also the orographic features of the catchment areas of the lakes played an important role here, for example, the distance from the river channel, the altitude at which a given catchment was located within the floodplain and

  8. Water balance of selected floodplain lake basins in the Middle Bug River valley

    NASA Astrophysics Data System (ADS)

    Dawidek, J.; Ferencz, B.

    2014-04-01

    This study is the first attempt in the literature on the subject of comparing water balance components for floodplain lake basins, depending on the type of a lake connection to the parent river. Research was carried out in the Bug River valley in 2007-2011 water years. Four types of connections were distinguished in the area under study. Simple water balance equation could only be used with regard to the lakes connected to the main river via the upstream crevasses. Detailed and individual water balance equations were developed with reference to the other types of lakes. Water gains and losses varied significantly in the lakes under study. Values of horizontal water balance components (inflow and outflow) of the floodplain lake in Wola Uhruska considerably prevailed over the vertical ones (precipitation and evaporation). Inflow of the Bug River waters was diverse during the time period under study and amounted from 600 000 to 2 200 000 m3 yr-1. Volumes of precipitation and evaporation were rather stable and amounted to approx. 30 000 m3 yr-1. The lowest disparity between horizontal and vertical water balance components was observed in the inter-levee lake. Both upstream inflow of rivers water and outflow from the lake (ranged from 0 in 2008 to 35 000 m3 yr-1 in 2009) were usually an order of magnitude higher than precipitation and evaporation from the lake surface (700-800 m3 yr-1). Study showed that the values and the proportion between aforementioned vertical and horizontal water balance elements were determined by the type of a lake connection to the Bug River. Storage volume showed no relationship to the type of connection, but resulted from individual features of the lakes (location within the valley, precipitation and evaporation volume, difference between water inflow and outflow).

  9. The influence of the Amazonian floodplain ecosystems on the trace element dynamics of the Amazon River mainstem (Brazil).

    PubMed

    Viers, Jérôme; Barroux, Guénaël; Pinelli, Marcello; Seyler, Patrick; Oliva, Priscia; Dupré, Bernard; Boaventura, Geraldo Resende

    2005-03-01

    The purpose of this paper is to forecast the role of riverine wetlands in the transfer of trace elements. One of the largest riverine wetlands in the world is the floodplain (várzea) of the Amazon River and its tributaries (Junk and Piedade, 1997). The central Amazon wetlands are constituted by a complex network of lakes and floodplains, named várzeas, that extend over more than 300,000 km2 (Junk, W.J., The Amazon floodplain--a sink or source for organic carbon? In Transport of Carbon and Minerals in Major World Rivers, edited by E.T. Degens, S. Kempe, R. Herrera, SCOPE/UNEP; 267-283, 1985.) and are among the most productive ecosystems in the world due to the regular enrichment in nutrients by river waters In order to understand if the adjacent floodplain of Amazon River have a significant influence on the trace element concentrations and fluxes of the mainstem, the concentrations of selected elements (i.e., Al, Mn, Fe, Co, Cu, Mo, Rb, Sr, Ba, and U) have been measured in the Amazon River water (Manacapuru Station, Amazonas State, Brazil) and in lake waters and plants (leaves) from a várzea(Ilha de Marchantaria, Amazonas State, Brazil) during different periods of the hydrological cycle. Four plant species (two perennial species: Pseudobombax munguba and Salix humboldtiana, and two annual herbaceous plants: Echinochloa polystachya and Eichhornia crassipes) were selected to represent the ecological functioning of the site. Time series obtained for dissolved Mn and Cu (<0.20 microm) in Amazon River water could not be explained by tributary mixing or instream processes only. Therefore, the contribution of the waters transiting the floodplains should be considered. These results suggest that the chemical composition of the waters draining these floodplains is controlled by reactions occurring at sediment-water and plant-water interfaces. Trace elements concentrations in the plants (leaves) vary strongly with hydrological seasonality. Based on the concentration data

  10. Patterns of forest succession and impacts of flood in the Upper Mississippi River floodplain ecosystem

    USGS Publications Warehouse

    Yin, Y.; Wu, Y.; Bartell, S.M.; Cosgriff, R.

    2009-01-01

    The widespread loss of oak-hickory forests and the impacts of flood have been major issues of ecological interest concerning forest succession in the Upper Mississippi River (UMR) floodplain. The data analysis from two comprehensive field surveys indicated that Quercus was one of the dominant genera in the UMR floodplain ecosystem prior to the 1993 flood and constituted 14% of the total number of trees and 28% of the total basal area. During the post-flood recovery period through 2006, Quercus demonstrated slower recovery rates in both the number of trees (4%) and basal area (17%). In the same period, Carya recovered greatly from the 1993 flood in terms of the number of trees (11%) and basal area (2%), compared to its minor status before the flood. Further analyses suggested that different species responded to the 1993 flood with varying tolerance and different succession strategies. In this study, the relation of flood-caused mortality rates and DBH, fm(d), can be expressed in negative exponential functions for each species. The results of this research also indicate that the growth functions are different for each species and might also be different between pre- and post-flood time periods. These functions indicate different survival strategies and emergent properties in responding to flood impacts. This research enhances our understanding of forest succession patterns in space and time in the UPR floodplain. And such understanding might be used to predict long-term impacts of floods on UMR floodplain forest dynamics in support of management and restoration. ?? 2009 Elsevier B.V.

  11. Impacts of Hurricane Katrina on floodplain forests of the Pearl River: Chapter 6A in Science and the storms-the USGS response to the hurricanes of 2005

    USGS Publications Warehouse

    Faulkner, Stephen; Barrow, Wylie; Couvillion, Brady R.; Conner, William; Randall, Lori; Baldwin, Michael

    2007-01-01

    Floodplain forests are an important habitat for Neotropical migratory birds. Hurricane Katrina passed through the Pearl River flood plain shortly after making landfall. Field measurements on historical plots and remotely sensed data were used to assess the impact of Hurricane Katrina on the structure of floodplain forests of the Pearl River.

  12. Uranium and Its Decay Products in Floodplain Sediments from the River Fal

    NASA Astrophysics Data System (ADS)

    Millward, G. E.; Blake, W. H.; Little, R.; Couldrick, L.

    2012-04-01

    European river basins are subject to longer-term storage of legacy contaminants in sedimentary sinks and their potential release presents a credible risk to achieving water quality targets required by the EU Water Framework Directive. The catchment of the River Fal, south west England, is extensively mineralised and has been greatly impacted by heavy metal mining. Uranium and radium were extracted and processed between 1870 and 1930 and spoil tips along the channel banks are assumed to have been a source of radionuclides into the river. Radionuclides were determined in five cores obtained from the river floodplain, including a reference core positioned upstream of the uranium mine enabling evaluation of its impact on past and contemporary sediment quality. The core was sectioned into 1 cm thick slices and they were analysed by gamma spectrometry for products of the U-238 decay series, i.e. Th-234 (a surrogate for U-238), Pb-214 (a surrogate for Ra-226), Pb-210 and fallout Am-241 and Cs-137. Peak Cs-137 concentrations at mid-depth were associated with fallout after atmospheric nuclear tests in 1963 and were used to estimate sedimentation rates. However, the activity concentrations of Pb-210 were elevated at all depths and the result indicated a significant input of unsupported Pb-210 (linked to processed spoil material) throughout the period of deposition. At some sites, peak activity concentrations of Th-234 suggested inputs from mining activity during major release and/or flood events. The cores downstream of the mine all had higher radionuclide inventories, of the order 105 Bq m-2, compared to the reference core due to the presences of products from the U-238 decay series. In addition, the inventories did not decrease systematically downstream indicating storage regions within the river channel. Storage of such legacy contaminants at levels in excess of contemporary environmental quality guidelines raises important questions and challenges for floodplain use and

  13. Floodplain Vegetation Productivity and Carbon Cycle Dynamics of the Middle Fork Flathead River of Northwest Montana

    NASA Astrophysics Data System (ADS)

    Oakins, A. J.; Kimball, J. S.; Relyea, S.; Stanford, J. A.

    2005-05-01

    River floodplains are vital natural features that store floodwaters, improve water quality, provide habitat, and create recreational opportunities. Recent studies have shown that strong interactions among flooding, channel and sediment movement, vegetation, and groundwater create a dynamic shifting habitat mosaic that promotes biodiversity and complex food webs. Multiple physical and environmental processes interact within these systems to influence forest productivity, including water availability, nutrient supply, soil texture, and disturbance history. This study is designed to quantify the role of groundwater depth and meteorology in determining spatial and temporal patterns of net primary productivity (NPP) within the Nyack floodplain of the Middle Fork Flathead River, Northwestern Montana. We examine three intensive field sites composed of mature, mixed deciduous and evergreen conifer forest with varying hydrologic and vegetative characteristics. We use a modified Biome-BGC ecosystem process model with field-collected data (LAI, increment growth cores, groundwater depth, vegetation sap-flow, and local meteorology) to describe the effects of floodplain groundwater dynamics on vegetation community structure, and carbon/nitrogen cycling. Initial results indicate that conifers are more sensitive than deeper-rooted deciduous species to variability in groundwater depth and meteorological conditions. Forest productivity also shows a non-linear response to groundwater depth. Sites with intermediate groundwater depths (0.2-0.5m) allow vegetation to maintain connectivity to groundwater over longer periods during the growing season, are effectively uncoupled from atmospheric constraints on photosynthesis, and generally have greater productivity. Shallow groundwater sites (<0.2m) are less productive due to the indirect effects of reduced soil aerobic decomposition and reduced plant available nitrogen.

  14. Channel changes and floodplain management in the meandering middle Ebro River, Spain

    NASA Astrophysics Data System (ADS)

    Ollero, Alfredo

    2010-05-01

    The 346 km of the middle Ebro River between Logroño and La Zaida is a free meandering channel in a wide floodplain. This reach contains a discontinuous riparian corridor, including valuable riparian forests and oxbow lakes. The Ebro has witnessed substantial changes in channel morphology, gravel bars, riparian vegetation and floodplain uses over the last 80 years. The growth in sinuosity, migrations and meander cut-offs have been frequent before 1981. Afterwards, bank protections and dykes have stabilized the channel. There has been a progressive and significant decrease of both the area covered by water and the gravel bars without plant colonization. As a result the width of the riparian corridor has been dramatically reduced for human use. The deceleration and near elimination of the free meander dynamics of the Ebro channel represent an important loss of natural heritage. Dams, land-use changes throughout the basin, and construction of flood defences that restrict the main channel have changed the river system behaviour, which urgently needs a management plan combining both improvement and risk reduction. The solution proposed is the creation of a "Fluvial Territory".

  15. Hydrologic scenarios for floodplain building in a vertically accreting, suspended sediment river

    NASA Astrophysics Data System (ADS)

    Alexander, J. S.; Scott, M. L.; Schmidt, J. C.

    2006-12-01

    Recent advances in dendrogeomorphology allow for precise age constraint on rates of floodplain building. We applied these techniques in our effort to evaluate the relative roles of flow regulation and invasive riparian vegetation in accelerating the rate of vertical accretion and channel narrowing of the dam-regulated upper Green River in Dinosaur National Monument, Colorado and Utah. Four large trenches were excavated into alluvial deposits that are now inundated by either common post-dam floods or rare post-dam high releases. We dated individual stratigraphic units using the recently developed stem-burial method (Friedman et al. 2005), as well as traditional cross-dating methods. These excavations indicate that episodic large floods with pre- dam recurrences of 5 to 10 years may vertically aggrade floodplains by up to 1.0 m. Smaller, more frequent, floods progressively create inset alluvial deposits that are subsequently colonized by native or non-native woody shrubs and trees. These lower elevation deposits serve as growing surfaces for both native and non- native riparian plants as well as stable platforms for deposition during occasional large post-dam floods that exceed the capacity of the dam's power plant. This style of floodplain building results in channel narrowing and loss of aquatic habitats. In the case of the upper Green River, the majority of channel narrowing occurred during two isolated events: (1) a rare basin-wide flood in late winter 1962, shortly before completion of Flaming Gorge Dam and (2) the largest post-dam bypass flood in 1983. Thick deposits of these ages occur in each trench, and this pattern correlates with the sequence of channel narrowing described by Allred and Schmidt (1999) 320 km downstream at the USGS gage near Green River, Utah. Our results suggest infrequent, controlled, high-magnitude dam releases may be an ineffective means of channel rejuvenation and vegetation control along vertically accreting, suspended sediment rivers

  16. Use of satellite image analysis to track wetland loss on the Murrumbidgee River floodplain in arid Australia, 1975-1998.

    PubMed

    Kingsford, R T; Thomas, R F

    2002-01-01

    Demonstrating the extent of wetland loss and its causes are essential for policy makers and managers. We used Landsat satellite imagery to show major wetland loss in the Lower Murrumbidgee floodplain on the Murrumbidgee River in arid Australia. Stratification of the floodplain according to hydrology, use of imagery from the same time of year and the separation of developed areas, using ancillary information were essential. There was considerable loss of floodplain area over a 23 year period (1975-1998), mainly in the Nimmie-Caira stratum (59% loss), as wetland areas were replaced by irrigation bays. There was also a significant increase in fragmentation. For floodplain areas distant from the river, flooding patterns were more difficult to identify because of infrequent flooding and primary reliance on rainfall. Landsat imagery provided a powerful tool for demonstrating long-term changes in wetland area, even in highly variable environments. Such information can demonstrate the ecological costs of water resource development on floodplains, forming a basis for policy and management of rivers.

  17. Untangling complex shallow groundwater dynamics in the floodplain wetlands of a southeastern U.S. coastal river

    NASA Astrophysics Data System (ADS)

    Kaplan, D.; MuñOz-Carpena, R.; Ritter, A.

    2010-08-01

    Understanding the hydrological functioning of tidally influenced floodplain forests is essential for advancing ecosystem protection and restoration goals in impacted systems. However, finding direct relationships between basic hydrological inputs and floodplain hydrology is hindered by complex interactions between surface water, groundwater, and atmospheric fluxes in a variably saturated matrix with heterogeneous soils, vegetation, and topography. Thus, an explanatory method for identifying common trends and causal factors is required. Dynamic factor analysis (DFA), a time series dimension reduction technique, models temporal variation in observed data as linear combinations of common trends, which represent unidentified common factors, and explanatory variables. In this work, DFA was applied to model water table elevation (WTE) in the floodplain of the Loxahatchee River (Florida, USA), where altered watershed hydrology has led to changing hydroperiod and salinity regimes and undesired vegetative changes in the floodplain forest. The technique proved to be a powerful tool for the study of interactions among 29 long-term, nonstationary hydrological time series (12 WTE series and 17 candidate explanatory variables). Regional groundwater circulation, surface water elevations, and spatially variable net local recharge (cumulative rainfall - cumulative evapotranspiration) were found to be the main factors explaining groundwater profiles. The relative importance of these factors was spatially related to floodplain elevation, distance from the river channel, and distance upstream from the river mouth. The resulting dynamic factor model (DFM) simulated the WTE time series well (overall coefficient of efficiency, Ceff = 0.91) and is useful for assessing management scenarios for ecosystem restoration and predicted sea level rise.

  18. Comparative analysis of the soil cover diversity in floodplain areas of the Partizanskaya River valley (Sikhote-Alin Mountains)

    NASA Astrophysics Data System (ADS)

    Nazarkina, A. V.

    2010-12-01

    The regularities of the soil cover formation and pattern in the Partizanskaya River valley (Sikhote-Alin Mountains) were revealed. The diversity of the soil cover was shown to depend on the landscape hydrological zone of the river basin, the structure of the floodplain, and the difference in flooding of the floodplain sections. The comparative assessment of the soil cover diversity using the Shannon index showed that, in the zone of accumulative landscapes, the soil cover diversity of the floodplain sections that were formed under the meandering of the river was higher than the diversity of the soil cover in the sections formed upon branching (furcation) of the channel. The maximum values of the Shannon index and the maximum supply with water characterize the floodplain in the mouth zone of the valley with the most stable conditions of soil formation. The determination of the diversity index for the soil cover and water supply of the floodplain sections is expedient in planning the economic activities in the valley.

  19. Tree growth and recruitment in a leveed floodplain forest in the Mississippi River Alluvial Valley, USA

    USGS Publications Warehouse

    Gee, Hugo K.W.; King, Sammy L.; Keim, Richard F.

    2014-01-01

    Flooding is a defining disturbance in floodplain forests affecting seed germination, seedling establishment, and tree growth. Globally, flood control, including artificial levees, dams, and channelization has altered flood regimes in floodplains. However, a paucity of data are available in regards to the long-term effects of levees on stand establishment and tree growth in floodplain forests. In this study, we used dendrochronological techniques to reconstruct tree recruitment and tree growth over a 90-year period at three stands within a ring levee in the Mississippi River Alluvial Valley (MAV) and to evaluate whether recruitment patterns and tree growth changed following levee construction. We hypothesized that: (1) sugarberry is increasing in dominance and overcup oak (Quercus lyrata) is becoming less dominant since the levee, and that changes in hydrology are playing a greater role than canopy disturbance in these changes in species dominance; and (2) that overcup oak growth has declined following construction of the levee and cessation of overbank flooding whereas that of sugarberry has increased. Recruitment patterns shifted from flood-tolerant overcup oak to flood-intolerant sugarberry (Celtis laevigata) after levee construction. None of the 122 sugarberry trees cored in this study established prior to the levee, but it was the most common species established after the levee. The mechanisms behind the compositional change are unknown, however, the cosmopolitan distribution of overcup oak during the pre-levee period and sugarberry during the post-levee period, the lack of sugarberry establishment in the pre-levee period, and the confinement of overcup oak regeneration to the lowest areas in each stand after harvest in the post-levee period indicate that species-specific responses to flooding and light availability are forcing recruitment patterns. Overcup oak growth was also affected by levee construction, but in contrast to our hypothesis, growth actually

  20. First Feedbacks on Restored Floodplain Lakes Sedimentation along the Rhône River

    NASA Astrophysics Data System (ADS)

    Michalkova, M.; Piegay, H.

    2009-04-01

    Sedimentation rates and processes were studied in eighteen restored floodplain lakes and channels of the Rhône River in south-eastern France. Whilst many authors have studied the sedimentation in former channels before restoration, little is known about post-restoration sedimentation rates and processes since these are only now becoming evident. The objective of study was therefore to evaluate the variability in post-restoration habitat conditions inside of floodplain lakes (inter-lake comparison) and to consider the temporal evolution of habitat conditions. The increase of the minimum discharge in the old Rhône channel and the removal of sediments in the floodplain lakes were the main issues of the Rhône River restoration project. In addition, the minimum discharge increase resulted in a higher water-table in the former Rhône channel. The sediment survey protocol was established and three steps were implemented: i) the measurement of the sedimentation rates based on the ratio between the mean sediment thickness and the time since the restoration works; ii) determination of connection discharge by piezometers and precise DGPS survey and iii) the statistical analysis of the relationships and inter-lake analysis (the characterization of connection frequency and to define the life expectancy of former channels). Changes in the connectivity between the main channel and other aquatic zones also influence the change in sedimentation rate through time. Multiple parameters such as age, channel geometry, mean annual sediment supply and frequency of connection, groundwater connection with the main channel and the type of sediments (sand, clay, silt, gravel) are included. The variability is in the inter-lakes function of restored reaches along the length of the Rhone corridor. Three hydro-geomorphological groups can be identified: 1. Systems characterized by rapid flows and the transport of sand and fine sediment (YEN, LUI, CIS) 2. Systems characterized by a wide range of

  1. Using environmental isotopes 2H and 18O for identification of infiltration processes in floodplain ecosystems of the River Elbe.

    PubMed

    Böhnke, R; Geyer, S; Kowski, P

    2002-03-01

    We examined a floodplain area in the middle section of the river Elbe Valley with regard to hydrogeological and hydrological processes using isotopic methods. Over two years, river water and groundwater have been analysed for temporal and spatial chemical and isotopic (delta2H and delta18O) changes. By these methods we assessed the flow dynamics of the river-groundwater infiltration system. At low and mean river stages there is a general hydraulic gradient from the higher areas at the margin of the valley towards the floodplain. During floods river water infiltrates into the adjacent aquifer not primarily through the river banks but first through surface water inflow from north to south, via depressions and gullies from the back of the floodplain. The early stage of river water infiltration is characterized by a sharp decrease in conductivity and in concentrations of SO4(2-) and Cl- in the hydraulically connected shallow aquifer. delta2H and delta18O values show a similar tendency. We observed a significant minimum in stable isotope ratios during the flood in March 1999. Using a simple mixing equation it was calculated that the groundwater in the upper, shallow aquifer consists of around 70% river water in the transition zone (well 13) during flooding.

  2. Field effects of pollutants in dynamic environments. A case study on earthworm populations in river floodplains contaminated with heavy metals.

    PubMed

    Klok, Chris; Goedhart, Paul W; Vandecasteele, Bart

    2007-05-01

    In industrialized countries river floodplains can be strongly polluted with heavy metals. Published studies on effects of heavy metal pollution on soil invertebrates in floodplains, however, are inconclusive. This is unexpected since studies in other less dynamic environments reported clear effects at even lower levels of pollution. Flooding induces extra variation in invertebrate biomass and abundance which may reduce the probability to detect heavy metal effects. In this paper we combine reported data from studies on river floodplains in The Netherlands and Belgium and statistically analyze the effect of heavy metals on species composition, biomass, density and individual weight of earthworms. Interaction effects of heavy metal stress and flooding are also considered. The results suggest clear effects of zinc and copper on all variables and interaction of heavy metals and flooding for individual weight.

  3. Characterization of subsurface stratigraphy along the lower American River floodplain using electrical resistivity, Sacramento, California, 2011

    USGS Publications Warehouse

    Burton, Bethany L.; Powers, Michael H.; Ball, Lyndsay B.

    2014-01-01

    In July 2011, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, completed a geophysical survey using electrical resistivity along an approximately 6-mile reach of the lower American River in Sacramento, California, to map near-surface lithological variations. This survey is a part of a manifold and comprehensive study of river-flow dynamics and geologic boundary-property knowledge necessary to estimate scour potential and levee erosion risk. Data were acquired on the left (south or west) bank between river mile 5 and 10.7 as well as a short section on the right bank from river mile 5.4 to 6. Thirteen direct-current resistivity profiles and approximately 8.3 miles of capacitively coupled resisistivity data were acquired along accessible areas of the floodplain between the levee and river bank. Capacitively coupled resistivity was used as a reconnaissance tool, because it allowed for greater spatial coverage of data but with lower resolution and depth of investigation than the DC resistivity method. The study area contains Pleistocene-age alluvial deposits, dominated by gravels, sands, silts, and clays, that vary in both lateral extent and depth. Several generations of lithologic logs were used to help interpret resistivity variations observed in the resistivity models.

  4. Flood-plain study of the Upper Iowa River in the vicinity of Decorah, Iowa

    USGS Publications Warehouse

    Christiansen, Daniel E.; Eash, David A.

    2008-01-01

    The city of Decorah, Iowa, has experienced severe flooding from the Upper Iowa River resulting in property damage to homes and businesses. Streamflow data from two U.S. Geological Survey (USGS) streamflow-gaging stations, the Upper Iowa River at Decorah, Iowa (station number 05387500), located upstream from the College Drive bridge; and the Upper Iowa River near Decorah, Iowa (station number 05388000), at the Clay Hill Road bridge (locally known as the Freeport bridge) were used in the study. The three largest floods on the Upper Iowa River at Decorah occurred in 1941, 1961, and 1993, for which the estimated peak discharges were 27,200 cubic feet per second (ft3/s), 20,200 ft3/s, and 20,500 ft3/s, respectively. Flood-discharge information can be obtained from the World Wide Web at URL (uniform resource locator) http://waterdata.usgs.gov/nwis/. In response to the need to provide the City of Decorah and other flood-plain managers with an assessment of the risks of flooding to properties and facilities along an 8.5-mile (mi) reach of the Upper Iowa River, the USGS, in cooperation with the City of Decorah, initiated a study to map 100- and 500-year flood-prone areas.

  5. Plains cottonwood's last stand: can it survive invasion of Russian olive onto the Milk River, Montana floodplain?

    PubMed

    Pearce, C M; Smith, D G

    2001-11-01

    Russian olive (Elaeagnus angustifolia L.) was introduced in 1950 onto one site on the Milk River floodplain, northern Montana, 10 km downstream from the Canada/United States border. To analyze dispersal of Russian olive from the point source between 1950 and 1999, we compared distribution, numbers, size structure, and mortality of Russian olive and plains cottonwood (Populus deltoides Marsh:) on an unregulated reach of the Milk River floodplain in southeastern Alberta and north-central Montana. Within 50 years, Russian olive in this reach has moved upriver into Alberta and downriver to the Fresno Reservoir. It is now present on 69 of the 74 meander lobes sampled, comprising 34%, 62%, and 61% of all Russian olive and plains cottonwood seedlings, saplings, and trees, respectively. On some meander lobes, Russian olive has colonized similar elevations on the floodplain as plains cottonwood and is oriented in rows paralleling the river channel, suggesting that recruitment may be related to river processes. Breakup ice had killed 400 Russian olive saplings and trees and damaged >1000 others on 30 of the meander lobes in 1996. Nevertheless, Russian olive now outnumbers cottonwood on many sites on the Milk River floodplain because its seeds can be dispersed by wildlife (particularly birds) and probably by flood water and ice rafts; seeds are viable for up to 3 years and germination can take place on bare and well-vegetated soils; and saplings and trees are less palatable to livestock and beaver than plains cottonwood. Without control, Russian olive could be locally dominant on the Milk River floodplain in all age classes within 10 years and replace plains cottonwood within this century.

  6. EFFECTS OF FLOOD PULSES ON NITRIFICATION RATES IN UPPER MISSISSIPPI RIVER FORESTED FLOODPLAINS, 2ND PRESENTATION IN 2007

    EPA Science Inventory

    Presentation is designed to enlighten the interested masses about potentials in nutrient trading and ecosystem services in our great river floodplain ecosystems. It is not intended for policy, rather to stimulate thought on the importance of natural flooding regimes and how to b...

  7. Spatial and Temporal Patterns of Nitrification Rates in Forested Floodplain Wetland Soils of Upper Mississippi River Pool 8, Journal Article

    EPA Science Inventory

    Overbank flooding is thought to be a critical process controlling nitrogen retention and cycling. In this study we investigated the effects of season and flood frequency on soil nitrification rates at ten sites in forested floodplains of Upper Mississippi River, Pool 8...A rough ...

  8. The risk of river pollution due to washout from contaminated floodplain water bodies during periods of high magnitude floods

    NASA Astrophysics Data System (ADS)

    Lyubimova, T.; Lepikhin, A.; Parshakova, Ya.; Tiunov, A.

    2016-03-01

    The risk of river pollution due to washout (removal of pollutants) from contaminated floodplain water bodies (floodplain lakes and quarries whose origin is related to the large-scale mining of nonmetallic building materials in the floodplain zone) during high magnitude flood periods is analyzed using a combination of one-, two- and three-dimensional hydrodynamic modeling and in situ measurements. The modeling performed for the floodplain water bodies contaminated by N compounds shows that during large magnitude floods washout occurs. The washout process consists of two stages: an initial rapid stage lasting about two hours during which the upper (3-4 m thick) layer is washed out, followed by a second stage when the concentration of NH4-N in the floodplain water body remains nearly constant. The maximum contaminant concentration in the river in the vicinity of a water intake for drinking water located 21 km downstream is attained about 9 h from the beginning of the flood; concentration of NH4-N can reach values several times larger than acceptable concentration guidelines. The initial primary peak in contaminant concentration at the water intake is followed by a slight decrease in contaminant concentration; a second peak related to the contaminant transport through the inundated floodplain subsequently occurs, after which the concentration slowly decreases, reaching acceptable values after 30-40 h. Contaminated floodplain water bodies located near drinking water supply systems are not significant sources of contamination during small and moderate floods, but during high magnitude floods, they can become sources of water pollution. Operational measures that can decrease potential health risks are discussed.

  9. Applicability of the flood-pulse concept in a temperate floodplain river ecosystem: Thermal and temporal components

    USGS Publications Warehouse

    Schramm, H.L.; Eggleton, M.A.

    2006-01-01

    Annual growth increments were calculated for blue catfish (Ictalurus furcatus) and flathead catfish (Pylodictis olivaris) from the lower Mississippi River (LMR) to assess hypothesized relationships between fish growth and floodplain inundation as predicted by the Flood-Pulse Concept. Variation in catfish growth increment was high for all age classes of both species, and growth increments were not consistently related to various measures of floodplain inundation. However, relationships became stronger, and usually direct, when water temperature was integrated with area and duration of floodplain inundation. Relationships were significant for four of six age classes for blue catfish, a species known to utilize floodplain habitats. Though similar in direction, relationships were weaker for flathead catfish, which is considered a more riverine species. Our results indicate the Flood-Pulse Concept applies more strongly to temperate floodplain-river ecosystems when thermal aspects of flood pulses are considered. We recommend that future management of the LMR should consider ways to 'recouple' the annual flood and thermal cycles. An adaptive management approach will allow further determination of important processes affecting fisheries production in the LMR. Copyright ?? John Wiley & Sons, Ltd.

  10. Exploring field vegetation reflectance as an indicator of soil contamination in river floodplains.

    PubMed

    Kooistra, L; Salas, E A L; Clevers, J G P W; Wehrens, R; Leuven, R S E W; Nienhuis, P H; Buydens, L M C

    2004-01-01

    This study investigated the relation between vegetation reflectance and elevated concentrations of the metals Ni, Cd, Cu, Zn and Pb in river floodplain soils. High-resolution vegetation reflectance spectra in the visible to near-infrared (400-1350 nm) were obtained using a field radiometer. The relations were evaluated using simple linear regression in combination with two spectral vegetation indices: the Difference Vegetation Index (DVI) and the Red-Edge Position (REP). In addition, a multivariate regression approach using partial least squares (PLS) regression was adopted. The three methods achieved comparable results. The best R(2) values for the relation between metals concentrations and vegetation reflectance were obtained for grass vegetation and ranged from 0.50 to 0.73. Herbaceous species displayed a larger deviation from the established relationships, resulting in lower R(2) values and larger cross-validation errors. The results corroborate the potential of hyperspectral remote sensing to contribute to the survey of elevated metal concentrations in floodplain soils under grassland using the spectral response of the vegetation as an indicator. Additional constraints will, however, have to be taken into account, as results are resolution- and location-dependent.

  11. Isotopic fractionation and trophic position of zooplankton species in the Upper Paraná River floodplain.

    PubMed

    Santana, A R A; Benedito, E; Ducatti, C; Lansac-Tôha, F A

    2011-02-01

    This study aimed to evaluate the isotopic fractionation and trophic position of three zooplankton species (Notodiaptomus amazonicus, Moina minuta and Bosmina hagmanni) in the Upper Paraná River floodplain. We predict that phytoplankton is the main food resource used by these species. Three zooplankton samples and three phytoplankton samples were taken from each sampling site, with three to four samples collected for each species. The number of individuals for samples varied according to the body size: from 100 to 130 individuals for Notodiaptomus amazonicus; 150 to 200 for Moina minuta; and from 250 to 300 for Bosmina hagmanni. The isotopic values for δ13C and δ15N were determined using mass spectrophotometer. The isotopic fractionation of 13C was performed according to the relationship Δ = δ13C zooplankton - δ13C phytoplankton. To determine the possible trophic position of these species, we used the expression TL = (δ15N zooplankton - δ15N phytoplankton)/Δ+ 1. The species showed high variation in isotopic fractionation and in trophic position in the different environments. We verified that the species use other food resources in addition to phytoplankton. The elucidation and understanding of the trophic position of the organisms based on stable isotopic analysis offers complementary information to traditional techniques. This analysis helps explain the flow of matter and energy in the food chain of floodplain aquatic environments as well as trace the trophic relationships involved in the ecological roles and strategies of distinct species. PMID:21437401

  12. Calibration of Two-dimensional Floodplain Modeling in the Atchafalaya River Basin Using SAR Interferometry

    NASA Technical Reports Server (NTRS)

    Jung, Hahn Chul; Jasinski, Michael; Kim, Jin-Woo; Shum, C. K.; Bates, Paul; Lee, Hgongki; Neal, Jeffrey; Alsdorf, Doug

    2012-01-01

    Two-dimensional (2D) satellite imagery has been increasingly employed to improve prediction of floodplain inundation models. However, most focus has been on validation of inundation extent, with little attention on the 2D spatial variations of water elevation and slope. The availability of high resolution Interferometric Synthetic Aperture Radar (InSAR) imagery offers unprecedented opportunity for quantitative validation of surface water heights and slopes derived from 2D hydrodynamic models. In this study, the LISFLOOD-ACC hydrodynamic model is applied to the central Atchafalaya River Basin, Louisiana, during high flows typical of spring floods in the Mississippi Delta region, for the purpose of demonstrating the utility of InSAR in coupled 1D/2D model calibration. Two calibration schemes focusing on Manning s roughness are compared. First, the model is calibrated in terms of water elevations at a single in situ gage during a 62 day simulation period from 1 April 2008 to 1 June 2008. Second, the model is calibrated in terms of water elevation changes calculated from ALOS PALSAR interferometry during 46 days of the image acquisition interval from 16 April 2008 to 1 June 2009. The best-fit models show that the mean absolute errors are 3.8 cm for a single in situ gage calibration and 5.7 cm/46 days for InSAR water level calibration. The optimum values of Manning's roughness coefficients are 0.024/0.10 for the channel/floodplain, respectively, using a single in situ gage, and 0.028/0.10 for channel/floodplain the using SAR. Based on the calibrated water elevation changes, daily storage changes within the size of approx 230 sq km of the model area are also calculated to be of the order of 107 cubic m/day during high water of the modeled period. This study demonstrates the feasibility of SAR interferometry to support 2D hydrodynamic model calibration and as a tool for improved understanding of complex floodplain hydrodynamics

  13. Flood effects on efflux and net production of nitrous oxide in river floodplain soils

    NASA Astrophysics Data System (ADS)

    Riaz, Muhammad; Bruderer, Christian; Niklaus, Pascal A.; Luster, Jörg

    2016-04-01

    Floodplain soils are often rich in nutrients and exhibit high spatial heterogeneity in terms of geomorphology, soil environmental conditions and substrate availability for processes involved in carbon and nutrient cycling. In addition, fluctuating water tables lead to temporally changing redox conditions. In such systems, there are ideal conditions for the occurrence of hot spots and moments of nitrous oxide emissions, a potent greenhouse gas. The factors that govern the spatial heterogeneity and dynamics of N2O formation in floodplain soils and the surface efflux of this gas are not fully understood. A particular issue is the contribution of N2O formation in the subsoil to surface efflux. We studied this question in the floodplain of a restored section of the Thur river (NE Switzerland) which is characterized by a flashy flow regime. As a consequence, the floodplain soils are unsaturated most of the time. We showed earlier that saturation during flood pulses leads to short phases of generally anoxic conditions followed by a drying phase with anoxic conditions within aggregates and oxic conditions in larger soil pores. The latter conditions are conducive for spatially closely-coupled nitrification-denitrification and related hot moments of nitrous oxide formation. In a floodplain zone characterized by about one meter of young, sandy sediments, that are mostly covered by the tall grass Phalaris arundinacea, we measured at several time points before and after a small flood event N2O surface efflux with the closed-chamber method, and assessed N2O concentrations in the soil air at four different depths using gas-permeable tubings. In addition, we calculated the N2O diffusivity in the soil from Radon diffusivity. The latter was estimated in-situ from the recovery of Radon concentration in the gas-permeable tubings after purging with ambient air. All these data were then used to calculate net N2O production rates at different soil depths with the gradient method. In

  14. Data documentation for the 1981 summer vegetation experiment. [Kansas River floodplain

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T. (Principal Investigator); Brisco, B.; Allen, C.

    1982-01-01

    The mobile agricultural radar sensor was used to collect data from 31 fields in the floodplain of the Kansas River east of Lawrence, Kansas during the summer of 1981. Corn, soybeans, and wheat crops were observed from May 1 to November 11. Radar backscattering measurements were acquired at 10.2 GHz for VV and VH polarizations at 50 deg incidence angles for all fields and at 30 deg, 40 deg, 50 deg, 60 deg, and 70 deg for nine of the 31 fields. Target parameters describing the vegatation and soil characteristics, such as plant moisture, plant height, soil moisture, etc., were also measured. The methodology, radar backscatter data and associated ground-truth data obtained during this experiment are documented.

  15. Methane flux from the Amazon River floodplain - Emissions during rising water

    NASA Technical Reports Server (NTRS)

    Bartlett, Karen B.; Crill, Patrick M.; Bonassi, Jose A.; Richey, Jeffrey E.; Harriss, Robert C.

    1990-01-01

    Methane flux data obtained during a period of high and falling water level in the course of the dry season of 1985 (the Amazon Boundary Layer Experiment, ABLE 2A) and a period of moderate and rising water during the wet season of 1987 (ABLE 2B) were used to characterize the influence of seasonal variations in the vegetation, water column depth, and chemistry, as well as atmospheric dynamics, on the methane flux from the Amazon River floodplain. It was found that the annual estimate of methane from wetlands is identical to the annual estimate made by Matthews and Fung (1987) (both at 111 Tg). However, it was found that peatlands between 50 and 70 N contribute 39 Tg, with the large areas of forested and nonforested bogs making up 37 Tg of this figure, while the figures of Matthews and Fung were 63 and 62 Tg, respectively.

  16. Kootenai River Floodplain Ecosystem Operational Loss Assessment, Protection, Mitigation and Rehabilitation, 2007-2008 Annual Report.

    SciTech Connect

    Merz, Norm

    2009-02-18

    The overarching goals of the 'Kootenai River Floodplain Ecosystem Operational Loss Assessment, Protection, Mitigation and Rehabilitation' Project (BPA Project No.2002-011-00) are to: (1) assess abiotic and biotic factors (i.e., geomorphologic, hydrological, aquatic and riparian/floodplain communities) in determining a definitive composition of ecological integrity, (2) develop strategies to assess and mitigate losses of ecosystem functions, and (3) produce a regional operational loss assessment framework. To produce a scientifically defensible, repeatable, and complete assessment tool, KTOI assembled a team of top scientists in the fields of hydrology, hydraulics, ornithology, entomology, statistics, and river ecology, among other expertise. This advisory team is known as the Research Design and Review Team (RDRT). The RDRT scientists drive the review, selection, and adaptive management of the research designs to evaluate the ecologic functions lost due to the operation of federal hydropower facilities. The unique nature of this project (scientific team, newest/best science, adaptive management, assessment of ecological functions, etc.) has been to work in a dynamic RDRT process. In addition to being multidisciplinary, this model KTOI project provides a stark contrast to the sometimes inflexible process (review, re-review, budgets, etc.) of the Columbia River Basin Fish and Wildlife Program. The project RDRT is assembled annually, with subgroups meeting as needed throughout the year to address project issues, analyses, review, and interpretation. Activities of RDRT coordinated and directed the selection of research and assessment methodologies appropriate for the Kootenai River Watershed and potential for regional application in the Columbia River Basin. The entire RDRT continues to meet annually to update and discuss project progress. RDRT Subcontractors work in smaller groups throughout the year to meet project objectives. Determining the extent to which

  17. Regionally nested patterns of fish assemblages in floodplain lakes of the Magdalena river (Colombia)

    PubMed Central

    Granado-Lorencio, Carlos; Serna, Andrés Hernández; Carvajal, Juan David; Jiménez-Segura, Luz Fernanda; Gulfo, Alejandra; Alvarez, Frank

    2012-01-01

    We investigated if fish assemblages in neotropical floodplain lakes (cienagas) exhibit nestedness, and thus offer support to the managers of natural resources of the area for their decision making. The location was floodplain lakes of the middle section of the Magdalena river, Colombia. We applied the nested subset analysis for the series of 30 cienagas (27 connected to the main river and three isolated). All fish were identified taxonomically in the field and the matrix for presence–absence in all the lakes was used for the study of the pattern of nestedness. The most diverse order was Characiformes (20 species), followed by Siluriformes (19 species). Characidae and Loricaridae were the richest families. The species found in all the lakes studied were migratory species (17), and sedentary species (33). Two species (Caquetaia kraussii and Cyphocharax magdalenae) were widespread across the cienagas archipelago (100% of incidence). Nestedness analysis showed that the distribution of species over the spatial gradient studied (840 km) is significantly nested. The cienagas deemed the most hospitable were Simiti, El Llanito, and Canaletal. Roughly, 13 out of the 50 species caught show markedly idiosyncratic distributions. The resulting dataset showed a strong pattern of nestedness in the distribution of Magdalenese fishes, and differed significantly from random species assemblages. Out of all the measurements taken in the cienagas, only the size (area) and local richness are significantly related to the range of order of nested subset patterns (r=–0.59 and –0.90, respectively, at p < 0.01). Differential species extinction is suggested as the cause of a nested species assemblage, when the reorganized matrix of species occurring in habitat islands is correlated with the island area. Our results are consistent with this hypothesis. PMID:22833801

  18. Low elevation inland habitats of the Willamette River floodplain support enhanced denitrification

    EPA Science Inventory

    Floodplain nitrate removal via denitrification in sediment provides an important ecosystem service that may be a valuable sink for nitrate pollution. At this time, much floodplain restoration is taking place with little consideration for in-situ nutrient processing, necessitating...

  19. Impact of former uranium mining activities on the floodplains of the Mulde River, Saxony, Germany.

    PubMed

    Bister, S; Birkhan, J; Lüllau, T; Bunka, M; Solle, A; Stieghorst, C; Riebe, B; Michel, R; Walther, C

    2015-06-01

    The Mulde River drains the former uranium mining areas in Saxony (Germany), which has led to a large-scale contamination of the river and the adjacent floodplain soils with radionuclides of the uranium decay series. The objective of the investigation is to quantify the long-term effect of former uranium mining activities on a river system. All of the investigated environmental compartments (water, sediment, soil) still reveal an impact from the former uranium mining and milling activities. The contamination of water has decreased considerably during the last 20 years due to the operation of water treatment facilities. The uranium content of the sediments decreased as well (on average by a factor of 5.6), most likely caused by displacement of contaminated material during flood events. Currently, the impact of the mining activities is most obvious in soils. For some of the plots activity concentrations of >200 Bq/kg of soil were detected for uranium-238. Alluvial soils used as grassland were found to be contaminated to a higher degree than those used as cropland.

  20. [Methanotrophic bacteria in cold seeps of the floodplains of northern rivers].

    PubMed

    Belova, S É; Oshkin, I Iu; Glagolev, M V; Lapshina, E D; Maksiutov, Sh Sh; Dedysh, S N

    2013-01-01

    Small mud volcanoes (cold seeps), which are common in the floodplains of northern rivers, are a potentially important, although poorly studied sources of atmospheric methane. Field research on the cold seeps of the Mukhrina River (Khanty-Mansiysk Autonomous okrug, Russia) revealed methane fluxes from these structures to be orders of magnitude higher than from equivalent areas of the mid-taiga bogs. Microbial communities developing around the seeps were formed under conditions of high methane concentrations, low temperatures (3-5 degrees C), and near-neutral pH. Molecular identification of methane-oxidizing bacteria from this community by analysis of the pmoA gene encoding particulate methane monooxygenase revealed both type I and type II methanotrophs (classes Gammaproteobacteria and Alphaproteobacteria, respectively), with predomination of type I methanotrophs. Among the latter, microorganisms related to Methylobacterpsychrophilus and Methylobacter tundripaludum, Crenothrix polyspora (a stagnant water dweller), and a number of methanotrophs belonging to unknown taxa were detected. Growth characteristics of two isolates were determined. Methylobactersp. CMS7 exhibited active growth at 4-10 degrees C, while Methylocystis sp. SB12 grew better at 20 degrees C. Experimental results confirmed the major role ofmethanotrophic gammaproteobacteria in controlling the methane emission from cold river seeps.

  1. Use of seasonal freshwater wetlands by fishes in a temperate river floodplain

    USGS Publications Warehouse

    Henning, Julie A.; Gresswell, Robert E.; Fleming, Ian A.

    2007-01-01

    This study examined the use of freshwater wetland restoration and enhancement projects (i.e. non-estuarine wetlands subject to seasonal drying) by fish populations. To quantify fish use of freshwater emergent wetlands and assess the effect of wetland enhancement (i.e. addition of water control structures), two enhanced and two unenhanced emergent wetlands were compared, as well as two oxbow habitats within the Chehalis River floodplain. Eighteen fish species were captured using fyke nets and emigrant traps from January to the beginning of June, with the most abundant being three-spined stickleback Gasterosteus aculeatus and Olympic mudminnow Novumbra hubbsi. Coho salmon Oncorhynchus kisutch was the dominant salmonid at all sites. Enhanced wetlands, with their extended hydroperiods, had significantly higher abundances of yearling coho salmon than unenhanced wetlands. Both enhanced and unenhanced emergent wetlands yielded higher abundances of non-game native fishes than oxbow habitats. Oxbow habitats, however, were dominated by coho salmon. Fish survival in the wetland habitats was dependent on emigration to the river before dissolved oxygen concentrations decreased and wetlands became isolated and stranding occurred. This study suggests that wetland enhancement projects with an outlet to the river channel appear to provide fishes with important temporary habitats if they have the opportunity to leave the wetland as dissolved oxygen levels deteriorate.

  2. [Methanotrophic bacteria in cold seeps of the floodplains of northern rivers].

    PubMed

    Belova, S É; Oshkin, I Iu; Glagolev, M V; Lapshina, E D; Maksiutov, Sh Sh; Dedysh, S N

    2013-01-01

    Small mud volcanoes (cold seeps), which are common in the floodplains of northern rivers, are a potentially important, although poorly studied sources of atmospheric methane. Field research on the cold seeps of the Mukhrina River (Khanty-Mansiysk Autonomous okrug, Russia) revealed methane fluxes from these structures to be orders of magnitude higher than from equivalent areas of the mid-taiga bogs. Microbial communities developing around the seeps were formed under conditions of high methane concentrations, low temperatures (3-5 degrees C), and near-neutral pH. Molecular identification of methane-oxidizing bacteria from this community by analysis of the pmoA gene encoding particulate methane monooxygenase revealed both type I and type II methanotrophs (classes Gammaproteobacteria and Alphaproteobacteria, respectively), with predomination of type I methanotrophs. Among the latter, microorganisms related to Methylobacterpsychrophilus and Methylobacter tundripaludum, Crenothrix polyspora (a stagnant water dweller), and a number of methanotrophs belonging to unknown taxa were detected. Growth characteristics of two isolates were determined. Methylobactersp. CMS7 exhibited active growth at 4-10 degrees C, while Methylocystis sp. SB12 grew better at 20 degrees C. Experimental results confirmed the major role ofmethanotrophic gammaproteobacteria in controlling the methane emission from cold river seeps. PMID:25509412

  3. Impact of former uranium mining activities on the floodplains of the Mulde River, Saxony, Germany.

    PubMed

    Bister, S; Birkhan, J; Lüllau, T; Bunka, M; Solle, A; Stieghorst, C; Riebe, B; Michel, R; Walther, C

    2015-06-01

    The Mulde River drains the former uranium mining areas in Saxony (Germany), which has led to a large-scale contamination of the river and the adjacent floodplain soils with radionuclides of the uranium decay series. The objective of the investigation is to quantify the long-term effect of former uranium mining activities on a river system. All of the investigated environmental compartments (water, sediment, soil) still reveal an impact from the former uranium mining and milling activities. The contamination of water has decreased considerably during the last 20 years due to the operation of water treatment facilities. The uranium content of the sediments decreased as well (on average by a factor of 5.6), most likely caused by displacement of contaminated material during flood events. Currently, the impact of the mining activities is most obvious in soils. For some of the plots activity concentrations of >200 Bq/kg of soil were detected for uranium-238. Alluvial soils used as grassland were found to be contaminated to a higher degree than those used as cropland. PMID:25791900

  4. Hydrologic conditions, habitat characteristics, and occurrence of fishes in the Apalachicola River floodplain, Florida; second annual report of progress, October 1993-September 1994

    USGS Publications Warehouse

    Light, Helen M.; Darst, Melanie R.; Grubbs, J.W.

    1995-01-01

    This report describes progress and interim results of the second year of a 4-year study. The purpose of the 4-year study is to describe aquatic habitat types in the Apalachicola River floodplain and quantify the amount of habitat inundated by the river at various stages. Final results will be used to determine possible effects of altered flows on floodplain habitats and their associated fish communities. The study is being conducted by the U.S. Geological Survey in cooperation with the Northwest Florida Water Management District as part of a comprehensive study of water needs throughout two large river basins in Florida, Georgia, and Alabama. By the end of the second year, approxi- mately 80 to 90 percent of field data collection was completed. Water levels at 56 floodplain and main channel locations at study sites were read numerous times during low water and once or twice during high water. Rating curves estimating the relationship between stage at a floodplain site and flow of the Apalachicola River at Chattahoochee are presented for 3 sites in the upper river. Elevation, substrate type, and amount of vegetative structure were described at 27 cross sections representing eight different floodplain tributary types at upper, middle, and lower river study sites. A summary of substrate and structure information from all cross sections is presented. Substrate and structure characteristics of floodplain habitats inundated when river flow was at record low flow, mean annual low flow, and mean flow are described for 3 cross sections in the upper river. Digital coverage of high-altitude infra-red aerial photography was processed for use in a Geographic Information System which will be used to map aquatic habitats in the third year of the study. A summary of the literature on fish utilization of floodplain habitats is described. Eighty-one percent of the species collected in the main channel of the Apalachicola River are known to occur in floodplain habitats of eastern

  5. Consistent trophic patterns among fishes in lagoon and channel habitats of a tropical floodplain river: Evidence from stable isotopes

    NASA Astrophysics Data System (ADS)

    Roach, Katherine A.; Winemiller, Kirk O.; Layman, Craig A.; Zeug, Steven C.

    2009-07-01

    The relationship between food web dynamics and hydrological connectivity in rivers should be strongly influenced by annual flood pulses that affect primary production dynamics and movement of organic matter and consumer taxa. We sampled basal production sources and fishes from connected lagoons and the main channel of a low-gradient, floodplain river within the Orinoco River Basin in Venezuela. Stable isotope analysis was used to model the contribution of four basal production sources to fishes, and to examine patterns of mean trophic position during the falling-water period of the annual flood cycle. IsoSource, a multi-source mixing model, indicated that proportional contributions from production sources to fish assemblages were similar in lagoons and the main channel. Although distributions differed, the means for trophic positions of fish assemblages as well as individual species were similar between the two habitats. These findings contradict recent food web studies conducted in temperate floodplain rivers that described significant differences in trophic positions of fishes from slackwater and floodplain versus main channel habitats. Low between-habitat trophic variation in this tropical river probably results from an extended annual flood pulse (ca. 5 mo.) that allows mixing of sestonic and allochthonous basal production sources and extensive lateral movements of fishes throughout the riverscape.

  6. Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River basin

    NASA Astrophysics Data System (ADS)

    Zuijdgeest, A. L.; Zurbrügg, R.; Blank, N.; Fulcri, R.; Senn, D. B.; Wehrli, B.

    2015-12-01

    Floodplains are important biogeochemical reactors during fluvial transport of carbon and nutrient species towards the oceans. In the tropics and subtropics, pronounced rainfall seasonality results in highly dynamic floodplain biogeochemistry. The massive construction of dams, however, has significantly altered the hydrography and chemical characteristics of many (sub)tropical rivers. In this study, we compare organic-matter and nutrient biogeochemistry of two large, contrasting floodplains in the Zambezi River basin in southern Africa: the Barotse Plains and the Kafue Flats. Both systems are of comparable size but differ in anthropogenic influence: while the Barotse Plains are still in large parts pristine, the Kafue Flats are bordered by two hydropower dams. The two systems exhibit different flooding dynamics, with a larger contribution of floodplain-derived water in the Kafue Flats and a stronger peak flow in the Barotse Plains. Distinct seasonal differences have been observed in carbon and nutrient concentrations, loads, and export and retention behavior in both systems. The simultaneous retention of particulate carbon and nitrogen and the net export of dissolved organic and inorganic carbon and nitrogen suggested that degradation of particulate organic matter was the dominant process influencing the river biogeochemistry during the wet season in the Barotse Plains and during the dry season in the Kafue Flats. Reverse trends during the dry season indicated that primary production was important in the Barotse Plains, whereas the Kafue Flats seemed to have both primary production and respiration occurring during the wet season, potentially occurring spatially separated in the main channel and on the floodplain. Carbon-to-nitrogen ratios of particulate organic matter showed that soil-derived material was dominant year-round in the Barotse Plains, whereas the Kafue Flats transported particulate organic matter that had been produced in the upstream reservoir during

  7. Impact of drying and re-flooding of sediment on phosphorus dynamics of river-floodplain systems.

    PubMed

    Schönbrunner, Iris M; Preiner, Stefan; Hein, Thomas

    2012-08-15

    One of the consequences of human impacts on floodplains is a change in sedimentation leading to enhanced floodplain aggradation. Thus, accumulated sediments rich in nutrients might interfere with floodplain restoration. In this study we investigated the phosphorus release behavior of sediments from shallow backwaters of an isolated floodplain of the Danube River situated east of the city of Vienna with the aim to understand the effects of changes in dry/wet cycles on established floodplain sediments. In the light of restoration plans aiming at increased surface water exchange with the river main channel, the response of sediments to frequent alternations between desiccation and inundation periods is a key issue as changes of sediment properties are expected to affect phosphorus release. In order to determine the effect of changing hydrological conditions on internal phosphorus loading, we exposed sediments to different dry/wet treatments in a laboratory experiment. Total phosphorus (TP) release from sediments into the water column increased with increasing duration of dry periods prior to re-wetting. Partial correlation analysis showed significant positive correlations between ΔTP and ΔNH(4)(+) as well as between ΔTP and ΔFe(3+) concentrations (Δ refers to the difference between the final and initial concentration during the wetting period), indicating that enhanced mineralization rates leading to a concomitant release of NH(4)(+) and TP and the reduction of iron hydroxides leading to a concomitant release of Fe(3+) and TP are the mechanisms responsible for the rise in TP. Repeated drying and wetting resulted in elevated phosphorus release. This effect was more pronounced when drying periods led to an 80% reduction in water content, indicating that the degree of drying is a major determinant controlling phosphorus release upon re-wetting. The reconnection of isolated floodplains will favor fluctuating hydrologic conditions and is therefore expected to

  8. Impact of drying and re-flooding of sediment on phosphorus dynamics of river-floodplain systems.

    PubMed

    Schönbrunner, Iris M; Preiner, Stefan; Hein, Thomas

    2012-08-15

    One of the consequences of human impacts on floodplains is a change in sedimentation leading to enhanced floodplain aggradation. Thus, accumulated sediments rich in nutrients might interfere with floodplain restoration. In this study we investigated the phosphorus release behavior of sediments from shallow backwaters of an isolated floodplain of the Danube River situated east of the city of Vienna with the aim to understand the effects of changes in dry/wet cycles on established floodplain sediments. In the light of restoration plans aiming at increased surface water exchange with the river main channel, the response of sediments to frequent alternations between desiccation and inundation periods is a key issue as changes of sediment properties are expected to affect phosphorus release. In order to determine the effect of changing hydrological conditions on internal phosphorus loading, we exposed sediments to different dry/wet treatments in a laboratory experiment. Total phosphorus (TP) release from sediments into the water column increased with increasing duration of dry periods prior to re-wetting. Partial correlation analysis showed significant positive correlations between ΔTP and ΔNH(4)(+) as well as between ΔTP and ΔFe(3+) concentrations (Δ refers to the difference between the final and initial concentration during the wetting period), indicating that enhanced mineralization rates leading to a concomitant release of NH(4)(+) and TP and the reduction of iron hydroxides leading to a concomitant release of Fe(3+) and TP are the mechanisms responsible for the rise in TP. Repeated drying and wetting resulted in elevated phosphorus release. This effect was more pronounced when drying periods led to an 80% reduction in water content, indicating that the degree of drying is a major determinant controlling phosphorus release upon re-wetting. The reconnection of isolated floodplains will favor fluctuating hydrologic conditions and is therefore expected to

  9. Influence of deposition of fine plant debris in river floodplain shrubs on flood flow conditions - The Warta River case study

    NASA Astrophysics Data System (ADS)

    Mazur, Robert; Kałuża, Tomasz; Chmist, Joanna; Walczak, Natalia; Laks, Ireneusz; Strzeliński, Paweł

    2016-08-01

    This paper presents problems caused by organic material transported by flowing water. This material is usually referred to as plant debris or organic debris. Its composition depends on the characteristic of the watercourse. For lowland rivers, the share of the so-called small organic matter in plant debris is considerable. This includes both various parts of water plants and floodplain vegetation (leaves, stems, blades of grass, twigs, etc.). During floods, larger woody debris poses a significant risk to bridges or other water engineering structures. It may cause river jams and may lead to damming of the flowing water. This, in turn, affects flood safety and increases flood risk in river valleys, both directly and indirectly. The importance of fine plant debris for the phenomenon being studied comes down to the hydrodynamic aspect (plant elements carried by water end up on trees and shrubs, increase hydraulic flow resistance and contribute to the nature of flow through vegetated areas changed from micro-to macro-structural). The key part of the research problem under analysis was to determine qualitative and quantitative debris parameters and to establish the relationship between the type of debris and the type of land use of river valleys (crop fields, meadows and forested river sections). Another problem was to identify parameters of plant debris for various flow conditions (e.g. for low, medium and flood flows). The research also included an analysis of the materials deposited on the structure of shrubs under flood flow conditions during the 2010 flood on the Warta River.

  10. An Assessment of Habitat Quality Using Dissolved Oxygen Concentrations in Floodplain Water Bodies in Relation to River Flow and Mainstem Connectivity

    NASA Astrophysics Data System (ADS)

    Stofleth, J.; Andrews, E. S.; White, J. Q.

    2011-12-01

    The floodplains of the Apalachicola River, Florida include an intricate network of sloughs, lakes and wetlands. These floodplain water bodies provide essential spawning and nursery areas for a diverse array of aquatic organisms. The frequency and duration of Apalachicola River flows sufficient to hydraulically connect and thereby activate these floodplain features has decreased over time due to upstream dams, diversions, and modification to the channel geometry (incision and widening). The main objective of this study is to characterize the relationship between a key water quality parameter, dissolved oxygen (DO), to the hydraulic connectivity of the ecologically-important large slough systems within the Apalachicola River floodplain over a range of flow conditions. When DO concentrations drop, the quality of habitat for fish, invertebrates and other aquatic organisms are impacted. Hydraulic connection between the river and the floodplain sloughs contributes markedly to DO levels in the sloughs. To characterize the relationship between hydraulic connectivity and water quality, water level, DO, and temperature data were continuously monitored within four (4) major floodplain sloughs, one (1) oxbow lake, and mainstem (control) from August 2009 to January 2011. A comparison was made between statistically representative DO concentrations (daily mean, diurnal range, daily minimum and maximum) for each site and in the river. River discharge was estimated at each site from nearby gages. By examining distinct changes in DO signatures with increasing flow, it was possible to determine the approximate flow at which the sloughs and oxbow lakes begin to become activated or hydraulically connected (flowing condition) to the mainstem of the Apalachicola River, and at what flow rates these floodplain wetlands become fully connected. Based on this data, we drew conclusions about the availability of suitable habitat for native fish species in these slough systems across a range of

  11. The use of portable instruments for mapping contaminants in the floodplain of the Ploucnice River (Czech Republic)

    NASA Astrophysics Data System (ADS)

    Elznicova, Jitka; Sikora, Martin; Slaba, Eva; Popelka, Jan; Hosek, Michal; Matys Grygar, Tomas

    2015-04-01

    The Ploucnice River (the Czech Republic) was contaminated by uranium mining in the areas of Hamr na Jezere and Straz pod Ralskem mainly in 1971-1987. The pollutants are now deposited all over the floodplain of the river. In 2005 the aerial mapping of radioactive pollution in the floodplain of the Ploucnice River was performed at a height of 80 m above the ground in grid 250 x 250 m. That survey showed uneven, highly localised deposition of gamma-emitting nuclides along nearly the entire reach of the Ploucnice River. We studied several of those radioactivity hotspots 10-25 km downstream from the uranium mining area in aim to understand the reasons for that heterogeneity. The contamination of the floodplain was analysed mainly by two portable (handheld) instruments. The gamma-spectrometer DISA 400A was used for measuring the total surface gamma activity (main target nuclide was Ra-226). Very effective was also the use of portable X-ray fluorescence spectrometer (XRF) Olympus Innov-X (DELTA Premium), which provides fast analysis of more than 30 elements, such as pollutants (Ba, Ni, Pb, U and Zn) and grain-size sensitive lithogenic elements (Al, Si, Zr, Rb). Besides pollution mapping, XRF also allows for mapping sediment lithology using Al/Si or Rb/Zr element ratios (both proportional to the percentage of fine fraction). The field gamma spectrometry and XRF was performed with points 2-30 meters spaced, which revealed that hotspots according to low resolution (250 m) aerial mapping is composed of one or several strongly polluted areas with sizes up to several tens of metres. Similarly heterogeneous was also the distribution of sediment lithology in the floodplain. In some cases, micromorphology of the floodplain, formed mainly by the past meander abandonments and channel shifts was responsible for the heterogeneity of the pollution. To understand the floodplain development we used old maps and aerial photographs. The Czech Republic has an extensive archive of historical

  12. A mid to late Holocene history of floodplain and terrace reworking along the middle Delaware River valley, USA

    NASA Astrophysics Data System (ADS)

    Stinchcomb, Gary E.; Driese, Steven G.; Nordt, Lee C.; Allen, Peter M.

    2012-10-01

    This study tests and refines the traditional floodplain development model for the partly confined middle Delaware River valley, which has shown that the main channel was relatively stable and flanked by a 6000-8000 year old, vertically accreting alluvial terrace. The Holocene alluvial processes and history presented here in 6 fluvial phases were reconstructed using morphostratigraphy, 36 profile descriptions, 332 grain size analyses, and 82 14C ages from soil trenches, auger borings, and archaeological excavations. Fluvial phases I-III largely validate previous reconstructions showing a late Pleistocene (I: > 10.7 ka) braided stream transition into an early Holocene wandering stream with prolonged floodplain stability (II: 10.7-8 ka), followed by early-middle Holocene erosion and then deposition (III: 8-5 ka). The early and middle Holocene changes in alluvial stratigraphy and sedimentology broadly correlate with climatically derived Holocene subdivisions, suggesting climate change partly controls alluvial response along the middle Delaware River valley. This study documents for the first time a middle Holocene episode of channel incision occurring sometime between 6.0 and 5.0 ka. Although the results reconfirm that the majority of alluvial landforms are composed of vertical accretion deposits, we present here new evidence of oblique, abandoned channel, and lateral accretion deposits inset to similar landforms with different formation histories (i.e., polycyclic terrace development), depicting a river valley that has experienced floodplain and terrace reworking. The majority of floodplain and terrace reworking occurs during the late-middle and late Holocene phases IV-VI (5.5-0 ka), following the middle Holocene incision event. These phases demonstrate floodplain reworking processes in the form of channel abandonment, stripping, flood channeling, and convex bank erosion. The subsequent space filled rapidly with evidence of multistory soil formation, and eventually

  13. Characterization of redox-related soil microbial communities along a river floodplain continuum by fatty acid methyl ester (FAME) and 16S rRNA genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Redox states affect substrate availability and energy transformation, and, thus, play a crucial role in regulating soil microbial abundance, diversity, and community structure. We evaluated microbial communities in soils under oxic, intermittent, and anoxic conditions along a river floodplain conti...

  14. Patterns of floodplain sediment deposition along the regulated lower Roanoke River, North Carolina: annual, decadal, centennial scales

    USGS Publications Warehouse

    Hupp, Cliff R.; Schenk, Edward R.; Kroes, Daniel; Willard, Debra A.; Townsend, Phil A.; Peet, Robert K.

    2015-01-01

    The lower Roanoke River on the Coastal Plain of North Carolina is not embayed and maintains a floodplain that is among the largest on the mid-Atlantic Coast. This floodplain has been impacted by substantial aggradation in response to upstream colonial and post-colonial agriculture between the mid-eighteenth and mid-nineteenth centuries. Additionally, since the mid-twentieth century stream flow has been regulated by a series of high dams. We used artificial markers (clay pads), tree-ring (dendrogeomorphic) techniques, and pollen analyses to document sedimentation rates/amounts over short-, intermediate-, and long-term temporal scales, respectively. These analyses occurred along 58 transects at 378 stations throughout the lower river floodplain from near the Fall Line to the Albemarle Sound. Present sediment deposition rates ranged from 0.5 to 3.4 mm/y and 0.3 to 5.9 mm/y from clay pad and dendrogeomorphic analyses, respectively. Deposition rates systematically increased from upstream (high banks and floodplain) to downstream (low banks) reaches, except the lowest reaches. Conversely, legacy sediment deposition (A.D. 1725 to 1850) ranged from 5 to about 40 mm/y, downstream to upstream, respectively, and is apparently responsible for high banks upstream and large/wide levees along some of the middle stream reaches. Dam operations have selectively reduced levee deposition while facilitating continued backswamp deposition. A GIS-based model predicts 453,000 Mg of sediment is trapped annually on the floodplain and that little watershed-derived sediment reaches the Albemarle Sound. Nearly all sediment in transport and deposited is derived from the channel bed and banks. Legacy deposits (sources) and regulated discharges affect most aspects of present fluvial sedimentation dynamics. The lower river reflects complex relaxation conditions following both major human alterations, yet continues to provide the ecosystem service of sediment trapping.

  15. Patterns of floodplain sediment deposition along the regulated lower Roanoke River, North Carolina: Annual, decadal, centennial scales

    NASA Astrophysics Data System (ADS)

    Hupp, C. R.; Schenk, E. R.; Kroes, D. E.; Willard, D. A.; Townsend, P. A.; Peet, R. K.

    2015-01-01

    The lower Roanoke River on the Coastal Plain of North Carolina is not embayed and maintains a floodplain that is among the largest on the mid-Atlantic Coast. This floodplain has been impacted by substantial aggradation in response to upstream colonial and post-colonial agriculture between the mid-eighteenth and mid-nineteenth centuries. Additionally, since the mid-twentieth century stream flow has been regulated by a series of high dams. We used artificial markers (clay pads), tree-ring (dendrogeomorphic) techniques, and pollen analyses to document sedimentation rates/amounts over short-, intermediate-, and long-term temporal scales, respectively. These analyses occurred along 58 transects at 378 stations throughout the lower river floodplain from near the Fall Line to the Albemarle Sound. Present sediment deposition rates ranged from 0.5 to 3.4 mm/y and 0.3 to 5.9 mm/y from clay pad and dendrogeomorphic analyses, respectively. Deposition rates systematically increased from upstream (high banks and floodplain) to downstream (low banks) reaches, except the lowest reaches. Conversely, legacy sediment deposition (A.D. 1725 to 1850) ranged from 5 to about 40 mm/y, downstream to upstream, respectively, and is apparently responsible for high banks upstream and large/wide levees along some of the middle stream reaches. Dam operations have selectively reduced levee deposition while facilitating continued backswamp deposition. A GIS-based model predicts 453,000 Mg of sediment is trapped annually on the floodplain and that little watershed-derived sediment reaches the Albemarle Sound. Nearly all sediment in transport and deposited is derived from the channel bed and banks. Legacy deposits (sources) and regulated discharges affect most aspects of present fluvial sedimentation dynamics. The lower river reflects complex relaxation conditions following both major human alterations, yet continues to provide the ecosystem service of sediment trapping.

  16. Macrophytes in the Upper Paraná River floodplain: checklist and comparison with other large South American wetlands.

    PubMed

    Ferreira, Fernando Alves; Mormul, Roger Paulo; Thomaz, Sidinei Magela; Pott, Arnildo; Pott, Vali Joana

    2011-06-01

    Neotropical aquatic ecosystems have a rich aquatic flora. In this report, we have listed the aquatic flora of various habitats of the upper Paraná River floodplain by compiling data from literature and records of our own continuous collections conducted during the period 2007-2009. Our main purposes were to assess the macrophyte richness in the Paraná floodplain, to compare it with other South American wetlands and to assess whether the number of species recorded in South American inventories has already reached an asymptote. We recorded a total of 153 species of macrophytes in the Upper Paraná River floodplain, belonging to 100 genera and 47 families. In our comparative analysis, a clear floristic split from other South American wetlands was shown, except for the Pantanal, which is the closest wetland to the Paraná floodplain and, therefore, could be considered a floristic extension of the Pantanal. The species accumulation curve provides evidence that sampling efforts should be reinforced in order to compile a macrophyte flora census for South America. The high dissimilarity among South American wetlands, together with the lack of an asymptote in our species accumulation curve, indicates that the sampling effort needs to be increased to account for the actual species richness of macrophytes in this region.

  17. Estimating groundwater dynamics at a Colorado River floodplain site using historical hydrological data and climate information

    NASA Astrophysics Data System (ADS)

    Chen, Jinsong; Hubbard, Susan S.; Williams, Kenneth H.; Ficklin, Darren L.

    2016-03-01

    Long-term prediction of groundwater dynamics is important for assessing water resources and their impacts on biogeochemical cycling. However, estimating future groundwater dynamics is challenging due to the wide range of spatiotemporal scales in hydrological processes and uncertainty in future climate conditions. In this study, we develop a Bayesian model to combine small-scale historical hydrological data with large-scale climate information to estimate groundwater dynamics at a floodplain site in Rifle, Colorado. Although we have only a few years of groundwater elevation measurements, we have 47 years of streamflow data from a gaging station approximately 43 km upstream and long-term climate prediction on the Upper Colorado River Basin. To estimate future daily groundwater dynamics, we first develop a time series model to downscale the monthly streamflow derived from climate information to daily streamflow, and then transform the daily streamflow to groundwater dynamics at the downstream floodplain site. We use Monte Carlo methods to estimate future groundwater dynamics at the site through sampling from the joint posterior probability distribution. The results suggest that although future groundwater levels are expected to be similar to the current levels, the timing of the high groundwater levels is predicted to occur about 1 month earlier. The developed framework is extendable to other sites to estimate future groundwater dynamics given disparate data sets and climate projections. Additionally, the obtained estimates are being used as input to a site-specific watershed reactive transport models to predict how climate-induced changes will influence future biogeochemical cycling relevant to a variety of ecosystem services.

  18. A Holocene molluscan succession from floodplain sediments of the upper Lena River (Lake Baikal region), Siberia

    NASA Astrophysics Data System (ADS)

    White, Dustin; Preece, Richard C.; Shchetnikov, Alexander A.; Parfitt, Simon A.; Dlussky, Konstantin G.

    2008-05-01

    Floodplain sediments of the upper Lena River near Basovo in south-central Siberia have yielded the most detailed Holocene molluscan succession yet reported from the entire eastern Palaearctic. Over 72,500 shells from at least 28 species of terrestrial and 23 species of freshwater mollusc have been recovered, an abundance and diversity far higher than previously reported from the region. The molluscan assemblages are dominated by land snails, especially members of the genus Vallonia, represented by five species including Vallonia tenuilabris and two poorly known species Vallonia kamtschatica and Vallonia cf. chinensis. Other noteworthy species recovered include Gastrocopta theeli, Carychium pessimum, Vertigo extima (southernmost record), Vertigo microsphaera and the first Asian records of three other taxa ( Vertigo geyeri, Vertigo genesii and Vertigo parcedentata). Illustrations are provided for the critical species, since opinions differ about the status of various taxa and the correct names that should be used. The molluscan assemblages show clear successional trends during the early to mid-Holocene, reflecting episodes of dryness/wetness on the floodplain. Drier conditions at ca 6350 14C yr BP coincide with major changes in the archaeological record seen at other sites in the region but it remains unclear whether the two are linked. A prominent charcoal-rich horizon dated to ca 2800 14C yr BP marks a burning event in the catchment, which resulted in a two-fold increase in sediment accumulation rate. Remains of small mammals occurred throughout the sequence including a tooth of Microtus cf. maximowiczii, possibly the first occurrence of Ungar vole west of Lake Baikal. The faunal analyses have been integrated with a detailed pedological study of the sedimentary profile and a chronology was obtained by means of 12 AMS radiocarbon dates. This study provides the first detailed palaeoecological information relating to Holocene molluscan assemblages from the Cis

  19. Vertical distribution of anthropogenic radionuclides in cores from contaminated floodplains of the Yenisey River.

    PubMed

    Standring, W J F; Brown, J E; Dowdall, M; Korobova, E M; Linnik, V G; Volosov, A G

    2009-12-01

    The Mining and Chemical Industrial Combine, Zheleznogorsk (MCIC, previously known as Krasnoyarsk-26) on the River Yenisey has contaminated the surrounding environment with anthropogenic radionuclides as a result of discharges of radioactive wastes. The purpose of this study was to investigate the vertical distribution of anthropogenic contamination ((137)Cs and plutonium) within floodplain areas at different distances from the discharge point. Sites were chosen that display different characteristics with respect to periodic inundation with river water. Cs-137 activity concentrations were in the range 23-3770 Bq/kg (dry weight, d.w.); Pu-239,240 activity concentrations were in the range <0.01-14.2 Bq/kg (d.w.). Numerous sample cores exhibited sub-surface maxima which may be related to the historical discharges from the MCIC. Possible evidence indicating the deposition of earlier discharges at MCIC in deeper core layers was observed in the (238)Pu:(239,240)Pu activity ratio data: a Pu signal discernible from global fallout could be observed in numerous samples. Cs-137 and Pu-239,240 activity concentrations were correlated with the silt fraction (% by mass <63 microm) though no significant correlation was observed between (grain-size) normalised (137)Cs activity concentrations and distance downstream from the MCIC.

  20. Spatial structure of floodplain soil radionuclide contamination of the Enisey River near the Krasnoyarsk Mining and Chemical Combine

    NASA Astrophysics Data System (ADS)

    Linnik, V. G.; Brown, J. E.; Potapov, V. N.; Surkov, V. V.

    2012-04-01

    Enisey River floodplain soils were contaminated by technogenic radionuclides arising from operations at the Krasnoyarsk Mining Chemical Combine (KMCC) from 1958 to 1992. The radioecological situtation of the Enisey flood plain landscapes has been formed by the interaction of two factors: (i) characteristics of radionuclide discharges to the aquatic environment, (ii) hydrological regime of the Enisey River. The radionuclide discharge determined the potential extent of contamination, while the river hydrology was responsible for its transport over considerable distances. The erection of the dam of the Krasnoyarsk power station in 1970 changed the hydrological regime of the Enisey River. The water discharge and suspended sediments became uniform in all seasons and extreme floods, extending over high floodplain areas, ceased. The distribution of radioactive contamination within floodplain soils downstream from the KMCC was studied with the objectives of mapping contamination levels and analyzing the spatial structure of radionuclide distributions arising from floodplain formation. Based on a digital elevation model of floodplain landscapes at a strip of KMCC-Strelka the flooded area of the Enisey River was determined. In 1960 to 1970, deposition of contaminated sediments occurred at heights less than 6 m over an area of 99,2 km2, in 1970-1992 the flooded area with a height less than 3,5 m was of 38,2 km2. Since radiocaesium in the Enisey River primarily occurs in a well fixed sediment-associated form it is possible to use the analysis of landscape structure within the floodplain to detect lithologo-geomorphological zones corresponding to a varying degree of 137Cs contamination. Radionuclide contamination was measured using in situ gamma spectrometry and soil sampling undertaken at control points. Maximum 137Cs contamination densities (700 kBq m-2) were found on low- and middle-level floodplains of Beriozovy Island (16 km from the KMCC). The contamination density of 60

  1. Recovery of Arapaima sp. populations by community-based management in floodplains of the Purus River, Amazon.

    PubMed

    Petersen, T A; Brum, S M; Rossoni, F; Silveira, G F V; Castello, L

    2016-07-01

    In the present study a unique dataset on population abundance in various community-based management (CBM) and non-CBM areas is analysed to address the question of whether CBM can recover overexploited populations of Arapaima sp. in river-floodplain ecosystems. All non-CBM areas possessed depleted Arapaima sp. populations with a mean density of 0·01 individuals ha(-1) . Arapaima sp. population densities in all CBM areas changed over time from depleted to overexploited or well managed status, with a mean rate of increase of 77% year(-1) . Rates of Arapaima sp. population recovery in CBM areas differed, probably reflecting differences in ecosystem productivity and compliance with management regulations. These results indicate that CBM schemes can be effective tools for the recovery and conservation of fish populations with non-migratory life cycles in tropical river-floodplain ecosystems.

  2. Ground-cover vegetation in wetland forests of the lower Suwannee River floodplain, Florida, and potential impacts of flow reductions

    USGS Publications Warehouse

    Darst, Melanie R.; Light, Helen M.; Lewis, Lori J.

    2002-01-01

    Ground-cover vegetation was surveyed in wetland forests in the lower Suwannee River floodplain, Florida, in a study conducted by the U.S. Geological Survey in cooperation with the Suwannee River Water Management District from 1996 to 1999. Increased water use in the basin, supplied primarily from ground water, could reduce ground-water discharge to the river and flows in the lower Suwannee River. Many of the 282 ground-cover species found in wetland forests of the floodplain have distributions that are related to flow-dependent hydrologic characteristics of forest types, and their distributions would change if flows were reduced. Overall species diversity in the floodplain might decrease, and the composition of ground-cover vegetation in all forest types might change with flow reductions. The study area included forests within the 10-year floodplain of the lower Suwannee River from its confluence with the Santa Fe River to the lower limit of forests near the Gulf of Mexico. The floodplain is divided into three reaches (riverine, upper tidal, and lower tidal) due to variations in hydrology, vegetation, and soils with proximity to the coast. The riverine (non-tidal) reach had the greatest number of total species (203) and species unique to that reach (81). Mitchella repens, Toxicodendron radicans, and Axonopus furcatus were the most frequently dominant species in riverine bottomland hardwoods. Free-floating aquatic species, such as Spirodela punctata and Lemna valdiviana, were the dominant species in the wettest riverine swamps. The upper tidal reach had the lowest number of total species (116), only two species unique to that reach, and the lowest density of ground cover (26 percent). Panicum commutatum and Crinum americanum were frequent dominant species in upper tidal forests. The lower tidal reach had the highest ground-cover density (43 percent) and the second highest number of total species (183) and number of species unique to that reach (55). Saururus cernuus

  3. Recovery of Arapaima sp. populations by community-based management in floodplains of the Purus River, Amazon.

    PubMed

    Petersen, T A; Brum, S M; Rossoni, F; Silveira, G F V; Castello, L

    2016-07-01

    In the present study a unique dataset on population abundance in various community-based management (CBM) and non-CBM areas is analysed to address the question of whether CBM can recover overexploited populations of Arapaima sp. in river-floodplain ecosystems. All non-CBM areas possessed depleted Arapaima sp. populations with a mean density of 0·01 individuals ha(-1) . Arapaima sp. population densities in all CBM areas changed over time from depleted to overexploited or well managed status, with a mean rate of increase of 77% year(-1) . Rates of Arapaima sp. population recovery in CBM areas differed, probably reflecting differences in ecosystem productivity and compliance with management regulations. These results indicate that CBM schemes can be effective tools for the recovery and conservation of fish populations with non-migratory life cycles in tropical river-floodplain ecosystems. PMID:27094974

  4. Do hurricanes leave unique sedimentological records in floodplain settings? Connecticut River, Tropical Storm Irene and past flood events

    NASA Astrophysics Data System (ADS)

    Yellen, B.; Woodruff, J. D.; Kratz, L. N.; Fallon, A.

    2012-12-01

    In late August, 2011, Tropical Storm Irene passed directly over the Connecticut River watershed causing several low order streams to swell beyond prior historical maximum discharges. Although resultant discharge on the mainstem Connecticut River only amounted to a one in seven year-sized event, its sediment load far exceeded the historical discharge to sediment concentration relationship. Gravity cores taken in off-channel ponds following the hydrograph peak clearly showed deposition of storm-mobilized grains. Samples collected from floodplain forest locations also showed significant accumulation. In both depositional settings, grainsize, lithology and percent organics of flood event deposition differed dramatically from background sedimentation. Long cores collected from these same settings suggest that similar deposits from historical storms of record from the past three centuries are preserved in the floodplain sediment record.; Landsat 5 true color image collected on September 2, 2011 - two days after Tropical Storm Irene left the region.

  5. Floodplain architecture of an actively meandering river (the Ploučnice River, the Czech Republic) as revealed by the distribution of pollution and electrical resistivity tomography

    NASA Astrophysics Data System (ADS)

    Matys Grygar, T.; Elznicová, J.; Tůmová, Š.; Faměra, M.; Balogh, M.; Kiss, T.

    2016-02-01

    The aim of this study was to describe the floodplain architecture of the Ploučnice River, a naturally meandering river in the Czech Republic, using manual drill coring, the element analysis of sediments, and electrical resistivity tomography (ERT). The Ploučnice River has received diffuse pollution since the early twentieth century (mainly Pb) followed by a prominent, temporally well-defined pollution pulse from uranium mining in the 1970s and 1980s (mainly U and 226Ra). The pollution created a chemostratigraphic (temporal) framework for overbank fines. We used geographical information systems (GIS) to describe the channel's dynamics and visualise fluvial landforms. We sampled and analysed the finest floodplain sediments in the top 1 to 2 m of the floodplain fill (silty and sandy deposits), and we used ERT to visualise bodies of coarser and deeper strata at depths down to ~ 3 m. Several limits of ERT imaging have been found by a comparison of the resistivity domains with lithological descriptions of the cores: several decimetre-thick strata were not revealed (they are below the spatial resolution of that method), and humidity affected the results that were obtained in the topmost strata. The space for deposition of fluvial sediments in the Ploučnice River is being created by (1) natural lateral shifts in the channel (up to 0.5 m/year); (2) meander loop development and cutoffs at the timescale of decades to centuries and spatial scale of up to ~ 1/4 of the floodplain width; and (3) more substantial reorganisation of the channel structure by avulsions, probably at the timescale of centuries. These processes continuously create space for the deposition of overbank fines on the top of former point bars and in swales and abandoned channels. As a consequence of the speed of the channel shifts, at least 80% of the fine-grained top of the floodplain fill (overbank fines) was reworked over approximately three centuries.

  6. Gammaproteobacterial methanotrophs dominate cold methane seeps in floodplains of West Siberian rivers.

    PubMed

    Oshkin, Igor Y; Wegner, Carl-Eric; Lüke, Claudia; Glagolev, Mikhail V; Filippov, Illiya V; Pimenov, Nikolay V; Liesack, Werner; Dedysh, Svetlana N

    2014-10-01

    A complex system of muddy fluid-discharging and methane (CH4)-releasing seeps was discovered in a valley of the river Mukhrinskaya, one of the small rivers of the Irtysh Basin, West Siberia. CH4 flux from most (90%) of these gas ebullition sites did not exceed 1.45 g CH4 h(-1), while some seeps emitted up to 5.54 g CH4 h(-1). The δ(13)C value of methane released from these seeps varied between -71.1 and -71.3‰, suggesting its biogenic origin. Although the seeps were characterized by low in situ temperatures (3.5 to 5°C), relatively high rates of methane oxidation (15.5 to 15.9 nmol CH4 ml(-1) day(-1)) were measured in mud samples. Fluorescence in situ hybridization detected 10(7) methanotrophic bacteria (MB) per g of mud (dry weight), which accounted for up to 20.5% of total bacterial cell counts. Most (95.8 to 99.3%) methanotroph cells were type I (gammaproteobacterial) MB. The diversity of methanotrophs in this habitat was further assessed by pyrosequencing of pmoA genes, encoding particulate methane monooxygenase. A total of 53,828 pmoA gene sequences of seep-inhabiting methanotrophs were retrieved and analyzed. Nearly all of these sequences affiliated with type I MB, including the Methylobacter-Methylovulum-Methylosoma group, lake cluster 2, and several as-yet-uncharacterized methanotroph clades. Apparently, microbial communities attenuating methane fluxes from these local but strong CH4 sources in floodplains of high-latitude rivers have a large proportion of potentially novel, psychrotolerant methanotrophs, thereby providing a challenge for future isolation studies.

  7. Gammaproteobacterial Methanotrophs Dominate Cold Methane Seeps in Floodplains of West Siberian Rivers

    PubMed Central

    Oshkin, Igor Y.; Wegner, Carl-Eric; Lüke, Claudia; Glagolev, Mikhail V.; Filippov, Illiya V.; Pimenov, Nikolay V.; Liesack, Werner

    2014-01-01

    A complex system of muddy fluid-discharging and methane (CH4)-releasing seeps was discovered in a valley of the river Mukhrinskaya, one of the small rivers of the Irtysh Basin, West Siberia. CH4 flux from most (90%) of these gas ebullition sites did not exceed 1.45 g CH4 h−1, while some seeps emitted up to 5.54 g CH4 h−1. The δ13C value of methane released from these seeps varied between −71.1 and −71.3‰, suggesting its biogenic origin. Although the seeps were characterized by low in situ temperatures (3.5 to 5°C), relatively high rates of methane oxidation (15.5 to 15.9 nmol CH4 ml−1 day−1) were measured in mud samples. Fluorescence in situ hybridization detected 107 methanotrophic bacteria (MB) per g of mud (dry weight), which accounted for up to 20.5% of total bacterial cell counts. Most (95.8 to 99.3%) methanotroph cells were type I (gammaproteobacterial) MB. The diversity of methanotrophs in this habitat was further assessed by pyrosequencing of pmoA genes, encoding particulate methane monooxygenase. A total of 53,828 pmoA gene sequences of seep-inhabiting methanotrophs were retrieved and analyzed. Nearly all of these sequences affiliated with type I MB, including the Methylobacter-Methylovulum-Methylosoma group, lake cluster 2, and several as-yet-uncharacterized methanotroph clades. Apparently, microbial communities attenuating methane fluxes from these local but strong CH4 sources in floodplains of high-latitude rivers have a large proportion of potentially novel, psychrotolerant methanotrophs, thereby providing a challenge for future isolation studies. PMID:25063667

  8. Patchiness in a large floodplain river: Associations among hydrology, nutrients, and fish communities

    USGS Publications Warehouse

    DeJager, Nathan R.; Houser, Jeff N.

    2016-01-01

    Large floodplain rivers have internal structures shaped by directions and rates of water movement. In a previous study, we showed that spatial variation in local current velocities and degrees of hydrological exchange creates a patch-work mosaic of nitrogen and phosphorus concentrations and ratios in the Upper Mississippi River. Here, we used long-term fish and limnological data sets to test the hypothesis that fish communities differ between the previously identified patches defined by high or low nitrogen to phosphorus ratios (TN:TP) and to determine the extent to which select limnological covariates might explain those differences. Species considered as habitat generalists were common in both patch types but were at least 2 times as abundant in low TN:TP patches. Dominance by these species resulted in lower diversity in low TN:TP patches, whereas an increased relative abundance of a number of rheophilic (flow-dependent) species resulted in higher diversity and a more even species distribution in high TN:TP patches. Of the limnological variables considered, the strongest predictor of fish species assemblage and diversity was water flow velocity, indicating that spatial patterns in water-mediated connectivity may act as the main driver of both local nutrient concentrations and fish community composition in these reaches. The coupling among hydrology, biogeochemistry, and biodiversity in these river reaches suggests that landscape-scale restoration projects that manipulate hydrogeomorphic patterns may also modify the spatial mosaic of nutrients and fish communities. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

  9. QMRAcatch: Human-Associated Fecal Pollution and Infection Risk Modeling for a River/Floodplain Environment.

    PubMed

    Derx, Julia; Schijven, Jack; Sommer, Regina; Zoufal-Hruza, Christa M; van Driezum, Inge H; Reischer, Georg; Ixenmaier, Simone; Kirschner, Alexander; Frick, Christina; de Roda Husman, Ana Maria; Farnleitner, Andreas H; Blaschke, Alfred Paul

    2016-07-01

    Protection of drinking water resources requires addressing all relevant fecal pollution sources in the considered catchment. A freely available simulation tool, QMRAcatch, was recently developed to simulate concentrations of fecal indicators, a genetic microbial source tracking (MST) marker, and intestinal pathogens in water resources and to conduct a quantitative microbial risk assessment (QMRA). At the same time, QMRAcatch was successfully applied to a region of the Danube River in Austria, focusing on municipal wastewater emissions. Herein, we describe extension of its application to a Danube River floodplain, keeping the focus on fecal sources of human origin. QMRAcatch was calibrated to match measured human-associated MST marker concentrations for a dry year and a wet year. Appropriate performance characteristics of the human-associated MST assay were proven by simulating correct and false-positive marker concentrations, as determined in human and animal feces. With the calibrated tool, simulated and measured enterovirus concentrations in the rivers were compared. Finally, the calibrated tool allowed demonstrating that 4.5 log enterovirus and 6.6 log norovirus reductions must be achieved to convert current surface water to safe drinking water that complies with a health-based target of 10 infections person yr. Simulations of the low- and high-pollution scenarios showed that the required viral reductions ranged from 0 to 8 log. This study has implications for water managers with interests in assessing robust catchment protection measures and water treatment criteria by considering the fate of fecal pollution from its sources to the point of abstraction. PMID:27380068

  10. QMRAcatch: Human-Associated Fecal Pollution and Infection Risk Modeling for a River/Floodplain Environment.

    PubMed

    Derx, Julia; Schijven, Jack; Sommer, Regina; Zoufal-Hruza, Christa M; van Driezum, Inge H; Reischer, Georg; Ixenmaier, Simone; Kirschner, Alexander; Frick, Christina; de Roda Husman, Ana Maria; Farnleitner, Andreas H; Blaschke, Alfred Paul

    2016-07-01

    Protection of drinking water resources requires addressing all relevant fecal pollution sources in the considered catchment. A freely available simulation tool, QMRAcatch, was recently developed to simulate concentrations of fecal indicators, a genetic microbial source tracking (MST) marker, and intestinal pathogens in water resources and to conduct a quantitative microbial risk assessment (QMRA). At the same time, QMRAcatch was successfully applied to a region of the Danube River in Austria, focusing on municipal wastewater emissions. Herein, we describe extension of its application to a Danube River floodplain, keeping the focus on fecal sources of human origin. QMRAcatch was calibrated to match measured human-associated MST marker concentrations for a dry year and a wet year. Appropriate performance characteristics of the human-associated MST assay were proven by simulating correct and false-positive marker concentrations, as determined in human and animal feces. With the calibrated tool, simulated and measured enterovirus concentrations in the rivers were compared. Finally, the calibrated tool allowed demonstrating that 4.5 log enterovirus and 6.6 log norovirus reductions must be achieved to convert current surface water to safe drinking water that complies with a health-based target of 10 infections person yr. Simulations of the low- and high-pollution scenarios showed that the required viral reductions ranged from 0 to 8 log. This study has implications for water managers with interests in assessing robust catchment protection measures and water treatment criteria by considering the fate of fecal pollution from its sources to the point of abstraction.

  11. Gammaproteobacterial methanotrophs dominate cold methane seeps in floodplains of West Siberian rivers.

    PubMed

    Oshkin, Igor Y; Wegner, Carl-Eric; Lüke, Claudia; Glagolev, Mikhail V; Filippov, Illiya V; Pimenov, Nikolay V; Liesack, Werner; Dedysh, Svetlana N

    2014-10-01

    A complex system of muddy fluid-discharging and methane (CH4)-releasing seeps was discovered in a valley of the river Mukhrinskaya, one of the small rivers of the Irtysh Basin, West Siberia. CH4 flux from most (90%) of these gas ebullition sites did not exceed 1.45 g CH4 h(-1), while some seeps emitted up to 5.54 g CH4 h(-1). The δ(13)C value of methane released from these seeps varied between -71.1 and -71.3‰, suggesting its biogenic origin. Although the seeps were characterized by low in situ temperatures (3.5 to 5°C), relatively high rates of methane oxidation (15.5 to 15.9 nmol CH4 ml(-1) day(-1)) were measured in mud samples. Fluorescence in situ hybridization detected 10(7) methanotrophic bacteria (MB) per g of mud (dry weight), which accounted for up to 20.5% of total bacterial cell counts. Most (95.8 to 99.3%) methanotroph cells were type I (gammaproteobacterial) MB. The diversity of methanotrophs in this habitat was further assessed by pyrosequencing of pmoA genes, encoding particulate methane monooxygenase. A total of 53,828 pmoA gene sequences of seep-inhabiting methanotrophs were retrieved and analyzed. Nearly all of these sequences affiliated with type I MB, including the Methylobacter-Methylovulum-Methylosoma group, lake cluster 2, and several as-yet-uncharacterized methanotroph clades. Apparently, microbial communities attenuating methane fluxes from these local but strong CH4 sources in floodplains of high-latitude rivers have a large proportion of potentially novel, psychrotolerant methanotrophs, thereby providing a challenge for future isolation studies. PMID:25063667

  12. Modeling the influence of environmental heterogeneity on heavy metal exposure concentrations for terrestrial vertebrates in river floodplains.

    PubMed

    Schipper, Aafke M; Loos, Mark; Ragas, Ad M J; Lopes, João P C; Nolte, Boris T; Wijnhoven, Sander; Leuven, Rob S E W

    2008-04-01

    To analyze the influence of environmental heterogeneity on heavy metal exposure concentrations for terrestrial vertebrates in river floodplains, a spatially explicit exposure model has been constructed (SpaCE-model: Spatially explicit cumulative exposure model). This model simulates the environmental use of individual organisms by selecting model cells to be foraged in within a multicelled, heterogeneous landscape. Exposure durations and exposure concentrations are calculated for the selected cells, whereby exposure concentrations are dependent on the availability and contaminant concentrations of different diet items in each cell. The model was applied to a selection of 10 terrestrial vertebrate species, including six small mammalian and four top predator species. It was parameterized for cadmium contamination in a 285-ha, embanked floodplain area along the Rhine River in The Netherlands. Simulations of 1,000 individuals for each species resulted in intraspecies variation in exposure concentrations of between 11 and 39%, with the smallest values generally corresponding to the species with the largest home ranges. Comparison of the model results with cadmium concentrations measured in four of the species from the study area showed that the predicted variation accounted for 12 to 16% of the variation in the measurements. This indicates that environmental heterogeneity governs a minor part of the variation in metal exposure concentrations that can actually be observed in river floodplains.

  13. Seasonal dynamics of the fish assemblage in a floodplain lake at the confluence of the Negro and Amazon Rivers.

    PubMed

    Röpke, C P; Amadio, S A; Winemiller, K O; Zuanon, J

    2016-07-01

    The temporal effect of discharge and limnology on fish composition and species diversity in a floodplain lake at the confluence of the Amazon and Negro Rivers was evaluated. Species richness, abundance and assemblage composition were strongly influenced by seasonal discharge of the Amazon and Negro Rivers, which affects lateral connectivity, water conductivity and temperature. As a consequence, temporal β-diversity was high in the lake and the assemblage was dominated by seasonally transient species. Relatively large species known to feed on resources within the floodplain were captured almost exclusively during the flood period. During the dry season, the assemblage was dominated by fishes adapted to harsh conditions of high temperature and low dissolved oxygen concentrations. An open system with high spatial and temporal heterogeneity created by the meeting of two large rivers with different water chemistry, Lago Catalão has a dynamic fish assemblage. Given its high temporal β-diversity and abundance of fishes, many of great importance in local fisheries, Lago Catalão and other floodplain lakes in this region merit special attention for conservation. PMID:26563716

  14. Seasonal dynamics of the fish assemblage in a floodplain lake at the confluence of the Negro and Amazon Rivers.

    PubMed

    Röpke, C P; Amadio, S A; Winemiller, K O; Zuanon, J

    2016-07-01

    The temporal effect of discharge and limnology on fish composition and species diversity in a floodplain lake at the confluence of the Amazon and Negro Rivers was evaluated. Species richness, abundance and assemblage composition were strongly influenced by seasonal discharge of the Amazon and Negro Rivers, which affects lateral connectivity, water conductivity and temperature. As a consequence, temporal β-diversity was high in the lake and the assemblage was dominated by seasonally transient species. Relatively large species known to feed on resources within the floodplain were captured almost exclusively during the flood period. During the dry season, the assemblage was dominated by fishes adapted to harsh conditions of high temperature and low dissolved oxygen concentrations. An open system with high spatial and temporal heterogeneity created by the meeting of two large rivers with different water chemistry, Lago Catalão has a dynamic fish assemblage. Given its high temporal β-diversity and abundance of fishes, many of great importance in local fisheries, Lago Catalão and other floodplain lakes in this region merit special attention for conservation.

  15. The spatial and temporal trends of Cd, Cu, Hg, Pb and Zn in Seine River floodplain deposits (1994-2000)

    USGS Publications Warehouse

    Grosbois, C.; Meybeck, Michel; Horowitz, A.; Ficht, A.

    2006-01-01

    Fresh floodplain deposits (FD), from 11 key stations, covering the Seine mainstem and its major tributaries (Yonne, Marne and Oise Rivers), were sampled from 1994 to 2000. Background levels for Cd, Cu, Hg, Pb, and Zn were established using prehistoric FD and actual bed sediments collected in small forested sub-basins in the most upstream part of the basin. Throughout the Seine River Basin, FD contain elevated concentrations of Cd, Cu, Hg, Pb and Zn compared to local background values (by factors > twofold). In the Seine River Basin, trace element concentrations display substantial downstream increases as a result of increasing population densities, particularly from Greater Paris (10 million inhabitants), and reach their maxima at the river mouth (Poses). These elevated levels make the Seine one of the most heavily impacted rivers in the world. On the other hand, floodplain-associated trace element levels have declined over the past 7 years. This mirrors results from contemporaneous suspended sediment surveys at the river mouth for the 1984-1999 period. Most of these temporal declines appear to reflect reductions in industrial and domestic solid wastes discharged from the main Parisian sewage plant (Seine Aval). ?? 2005 Elsevier B.V. All rights reserved.

  16. Viruses and bacteria in floodplain lakes along a major Amazon tributary respond to distance to the Amazon River.

    PubMed

    Almeida, Rafael M; Roland, Fábio; Cardoso, Simone J; Farjalla, Vinícius F; Bozelli, Reinaldo L; Barros, Nathan O

    2015-01-01

    In response to the massive volume of water along the Amazon River, the Amazon tributaries have their water backed up by 100s of kilometers upstream their mouth. This backwater effect is part of the complex hydrodynamics of Amazonian surface waters, which in turn drives the variation in concentrations of organic matter and nutrients, and also regulates planktonic communities such as viruses and bacteria. Viruses and bacteria are commonly tightly coupled to each other, and their ecological role in aquatic food webs has been increasingly recognized. Here, we surveyed viral and bacterial abundances (BAs) in 26 floodplain lakes along the Trombetas River, the largest clear-water tributary of the Amazon River's north margin. We correlated viral and BAs with temperature, pH, dissolved inorganic carbon, dissolved organic carbon (DOC), phosphorus, nitrogen, turbidity, water transparency, partial pressure of carbon dioxide (pCO2), phytoplankton abundance, and distance from the lake mouth until the confluence of the Trombetas with the Amazon River. We hypothesized that both bacterial and viral abundances (VAs) would change along a latitudinal gradient, as the backwater effect becomes more intense with increased proximity to the Amazon River; different flood duration and intensity among lakes and waters with contrasting sources would cause spatial variation. Our measurements were performed during the low water period, when floodplain lakes are in their most lake-like conditions. Viral and BAs, DOC, pCO2, and water transparency increased as distance to the Amazon River increased. Most viruses were bacteriophages, as viruses were strongly linked to bacteria, but not to phytoplankton. We suggest that BAs increase in response to DOC quantity and possibly quality, consequently leading to increased VAs. Our results highlight that hydrodynamics plays a key role in the regulation of planktonic viral and bacterial communities in Amazonian floodplain lakes.

  17. Variations in trace element geochemistry in the Seine River Basin based on floodplain deposits and bed sediments

    USGS Publications Warehouse

    Horowitz, A.J.; Meybeck, Michel; Idlafkih, Z.; Biger, E.

    1999-01-01

    Between 1990 and 1995 a series of bed sediment, suspended sediment and fresh floodplain samples were collected within the Seine River Basin, in France, to evaluate variations in trace element geochemistry. Average background trace element levels for the basin were determined from the collection and subsequent analyses of bed sediment samples from small rural watersheds and from a prehistoric (5000 BP) site in Paris. Concentrations are relatively low, and similar to those observed for fine-grained bed sediments from unaffected areas in the United States and Canada. However, the concentrations are somewhat higher than the reference levels presently adopted by French water authorities for areas north of the Seine Basin, which have similar bedrock lithologies. Downstream trace element variations were monitored in 1994 and 1995 using fresh surficial floodplain samples that were collected either as dried deposits a few days after peak discharge, or immediately after peak discharge (under ??? 30 cm of water). Chemical comparisons between fresh floodplain deposits, and actual suspended sediments collected during flood events, indicate that, with some caveats, the former can be used as surrogates for the latter. The floodplain sediment chemical data indicate that within the Seine Basin, from the relatively unaffected headwaters through heavily affected urban streams, trace element concentrations vary by as much as three orders of magnitude. These trace element changes appear to be the result of both increases in population as well as concomitant increases in industrial activity. This article is a US government work and is in the public domain in the United States.

  18. Algal extracellular release in river-floodplain dissolved organic matter: response of extracellular enzymatic activity during a post-flood period

    PubMed Central

    Sieczko, Anna; Maschek, Maria; Peduzzi, Peter

    2015-01-01

    River-floodplain systems are susceptible to rapid hydrological events. Changing hydrological connectivity of the floodplain generates a broad range of conditions, from lentic to lotic. This creates a mixture of allochthonously and autochthonously derived dissolved organic matter (DOM). Autochthonous DOM, including photosynthetic extracellular release (PER), is an important source supporting bacterial secondary production (BSP). Nonetheless, no details are available regarding microbial extracellular enzymatic activity (EEA) as a response to PER under variable hydrological settings in river-floodplain systems. To investigate the relationship between bacterial and phytoplankton components, we therefore used EEA as a tool to track the microbial response to non-chromophoric, but reactive and ecologically important DOM. The study was conducted in three floodplain subsystems with distinct hydrological regimes (Danube Floodplain National Park, Austria). The focus was on the post-flood period. Enhanced %PER (up to 48% of primary production) in a hydrologically isolated subsystem was strongly correlated with β-glucosidase, which was related to BSP. This shows that—in disconnected floodplain backwaters with high terrestrial input—BSP can also be driven by autochthonous carbon sources (PER). In a semi-isolated section, in the presence of fresh labile material from primary producers, enhanced activity of phenol oxidase was observed. In frequently flooded river-floodplain systems, BSP was mainly driven by enzymatic degradation of particulate primary production. Our research demonstrates that EEA measurements are an excellent tool to describe the coupling between bacteria and phytoplankton, which cannot be deciphered when focusing solely on chromophoric DOM. PMID:25741326

  19. Quantifying floodplain and mainstem channel response to the removal of the Elwha River dams using "old school" techniques

    NASA Astrophysics Data System (ADS)

    Pess, G. R.; McHenry, M.; Peters, R.; Beechie, T. J.; Duda, J. J.; Liermann, M. C.; Bakke, P. D.; Morley, S. A.; McMillan, J. R.; Denton, K.

    2012-12-01

    In 2011 a multi-year deconstruction of two long-standing, high-head dams began on the Elwha River, Washington State. Over the past decade, we have been monitoring a variety of ecosystem attributes in the Elwha River basin to establish baseline conditions prior to one of the largest watershed restoration projects in the US. Our study design is tailored to the Elwha's geomorphic template, as different channel types are expected to respond differently to the large amount of sediment that will be released. A primary focus of this effort has been on the 28 km of floodplain channels below the dams (for every 1km of main stem habitat there is 1.35km of floodplain channel). Another focus has been on main stem channel features such as pool and riffle habitat, which are critical habitats for salmonids and other biota. How will these floodplain channels and mainstem channel features react to the large amount of sediment that is being released? We have used simple field techniques such as longitudinal profiles of floodplain channels, pebble counts, turbidity measurements, and the amount of sediment accumulation in pools and riffles to document baseline as well as "during dam removal" conditions. Early results indicate increased turbidity downstream of dams throughout deconstruction, suggesting there will be dramatic increases in fine sediment accumulations once dam removal is completed. We plan to continue using inexpensive methods to quantify the geomorphic and ecological change following dam removal in the Elwha River basin. These findings have direct implications for other dam removal projects.

  20. Floodplain development in engineered and natural settings determined with novel, high resolution 210-Pb geochronology: Insights from sedimentation studies along the lower Sacramento River, California

    NASA Astrophysics Data System (ADS)

    Aalto, R.; Singer, M. B.

    2008-12-01

    This presentation summarizes results from studies of floodplain sedimentation along the middle and lower Sacramento River that investigate processes using a new, high resolution methodology for 210Pb geochronology of 1-5 m floodplain cores. This approach accounts both for grain-size effects and radon ventilation and can resolve both deposition and erosional events. Therefore, it was possible to assess sedimentation over the past century within a wide array of sedimentary environments throughout the Sacramento Valley, where other techniques are limited. In particular, the Sacramento Valley has naturally low 210Pb activity due to its proximity to the Pacific Ocean, high rates of radon ventilation due to dry, porous floodplain sediment, and deposition of widely varying grain sizes - challenges that we have addressed with our enhanced methodology. The analytical approach affords a new ability to assess and directly compare dates and rates of sedimentation and erosion in disparate sedimentary environments throughout this complex fluvial dispersal system. We compare and contrast sediment deposition in engineered floodplains called bypasses, levied ancestral floodplains which serve as floodways during high flow, with sedimentation occurring in some remaining natural floodplains adjacent to the Sacramento River. We find that bypasses tend to accumulate sand and silt at their entrances, but that rates and textures decline rapidly with distance away from the channel. Essentially, a quasi-natural physical process of levee construction by advective overbank transport and deposition of sediment is operating (Singer and Aalto, ESPL, in press). These engineered floodways tend to siphon sediment out of the active channel, such that relatively low sedimentation rates prevail in floodplains and oxbow lakes within the active meander corridor that is bypassed. However, we document significant accumulation of fine-grained material in sedimentary sinks throughout floodplains upstream

  1. Vertical Accretion of the Rain Forest Floodplains and Levees: the Formation of Rias from Interaction of Black and White River Types in the Amazon River System.

    NASA Astrophysics Data System (ADS)

    Ori, G.; Franzinelli, E.

    2006-12-01

    The Amazon river system is dominated by the presence of rias, that is plaeovalleys paretially filled by sediment and harbouring almost standing bodies of water. Since the seminal work of Harald Sioli, it has been clear the paleovalleys have been formed in rivers (black type) poor in sediment and rich in organic matter during low stand periods of the sea level. Subsequently, the rivers rich in sediment (white type) damming of their mouths by the vertical accretion of the rivers rich in sediments (white type). This pattern is present in other rain forest fluvial systems and a good example is the Murray Lake in Papua New Guinea. These relations show that of the flood plain in tropical rain forest systems is strongly dominated by vertical accretion. This fact is also confirmed by the ubiquitous presence of levees inside channels (e.g. Rio Trombettas). Levees accrete vertically by the addition of single layers of sediment mostly entrapped by vegetation. The formation of permanent crevasse splays is also contributing to the levee accretion. Secondary channels are perched over the floodplain interface and totally bounded by levees. Consequently, the floodplain is dominated by lakes, permanent crevasse splays and levees assembled in vertical stacked bodies. The geological record shows examples of rain forest floodplains with similar facies and stratigraphic patterns..

  2. Effects of Jackson Lake Dam on the Snake River and its floodplain, Grand Teton National Park, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Marston, Richard A.; Mills, John D.; Wrazien, David R.; Bassett, Beau; Splinter, Dale K.

    2005-10-01

    In 1906, the Bureau of Reclamation created Jackson Lake Dam on the Snake River in what later became Grand Teton National Park. The geomorphic, hydrologic and vegetation adjustments downstream of the dam have yet to be documented. After a larger reservoir was completed further downstream in 1957, the reservoir release schedule from Jackson Lake Dam was changed in a manner that lowered the magnitude and frequency of floods. The stability of the Snake River exhibited a complex response to the change in flow regime. Close to major tributaries, the Snake River increased in total sinuosity and rates of lateral channel migration. Away from the influence of tributaries, the river experienced fewer avulsions and a decrease in sinuosity. Vegetation maps were constructed from 1945 and 1989 aerial photography and field surveys. Using these data, we determined how vegetation is directly related to the number of years since each portion of the floodplain was last occupied by the channel. The vegetation has changed from a flood-pulse dominated mosaic to a more terrestrial-like pattern of succession. Changes in the Snake River and its floodplain have direct implications on bald eagle habitat, moose habitat, fish habitat, safety of rafting and canoeing, and biodiversity at the community and species levels.

  3. Invasive riparian vegetation response to flow regimes and flood pulses in a braided river floodplain.

    PubMed

    Caruso, Brian S; Pithie, Callum; Edmondson, Laura

    2013-08-15

    This study evaluated flow regimes and flood pulse characteristics, and their influences on invasive riparian vegetation, in a free-flowing braided river in the Southern Alps, South Island, New Zealand. A 46-year gauged flow record was used to evaluate 67 flow metrics for the Ahuriri River, and five sets of colour aerial photographs over 20 years (1991-2011) were analysed to quantify temporal and spatial changes in vegetation (crack willow, Russell lupin, and grassland). The correlation between flow metrics and vegetation class cover for each aerial photo interval was analysed, and multiple regression models were developed. Significant changes in different invasive vegetation classes were found, including cover, number and sizes of patches, and distances from patches to primary channels. In addition to infrequent large floods, specific characteristics of small floods, high flows, low/baseflows, and extreme low flows had influences on different vegetation classes. Key metrics that appear to drive changes in cover and provide a useful multiple regression model include the largest flood peak, frequency of floods, and the time since the last flood for each air photo interval. Up to 25% of invasive vegetation cover was removed and bare substrate increased after the largest flood on record (approximately 50-year flood), and the amount of vegetation cover is highly variable over time and space. Within approximately six years, however, the proportion of vegetation recovered to pre-flood levels. The study reach appears to demonstrate the "shifting-mosaic steady state" conceptual model of riverine floodplains, where the total proportion of substrate, vegetation and water remain relatively constant over long time periods.

  4. Viruses and bacteria in floodplain lakes along a major Amazon tributary respond to distance to the Amazon River

    PubMed Central

    Almeida, Rafael M.; Roland, Fábio; Cardoso, Simone J.; Farjalla, Vinícius F.; Bozelli, Reinaldo L.; Barros, Nathan O.

    2015-01-01

    In response to the massive volume of water along the Amazon River, the Amazon tributaries have their water backed up by 100s of kilometers upstream their mouth. This backwater effect is part of the complex hydrodynamics of Amazonian surface waters, which in turn drives the variation in concentrations of organic matter and nutrients, and also regulates planktonic communities such as viruses and bacteria. Viruses and bacteria are commonly tightly coupled to each other, and their ecological role in aquatic food webs has been increasingly recognized. Here, we surveyed viral and bacterial abundances (BAs) in 26 floodplain lakes along the Trombetas River, the largest clear-water tributary of the Amazon River’s north margin. We correlated viral and BAs with temperature, pH, dissolved inorganic carbon, dissolved organic carbon (DOC), phosphorus, nitrogen, turbidity, water transparency, partial pressure of carbon dioxide (pCO2), phytoplankton abundance, and distance from the lake mouth until the confluence of the Trombetas with the Amazon River. We hypothesized that both bacterial and viral abundances (VAs) would change along a latitudinal gradient, as the backwater effect becomes more intense with increased proximity to the Amazon River; different flood duration and intensity among lakes and waters with contrasting sources would cause spatial variation. Our measurements were performed during the low water period, when floodplain lakes are in their most lake-like conditions. Viral and BAs, DOC, pCO2, and water transparency increased as distance to the Amazon River increased. Most viruses were bacteriophages, as viruses were strongly linked to bacteria, but not to phytoplankton. We suggest that BAs increase in response to DOC quantity and possibly quality, consequently leading to increased VAs. Our results highlight that hydrodynamics plays a key role in the regulation of planktonic viral and bacterial communities in Amazonian floodplain lakes. PMID:25788895

  5. Geomorphology and geologic characteristics of the Savannah River floodplain in the vicinity of the Savannah River Site, South Carolina and Georgia

    SciTech Connect

    Leeth, D.C. ); Nagle, D.D. )

    1994-03-01

    The potential for migration of contaminated ground water from the US Department of Energy Savannah River Site (SRS) beneath the Savannah River into Georgia (trans-river flow) is a subject of recent environmental concern. The degree of incision of the ancestral Savannah River into the local hydrogeologic framework is a significant consideration in the assessment of trans-river flow. The objective of this investigation is to identify the geologic formations which subcrop beneath the alluvium and the extent to which the river has incised regional confining beds. To meet this objective 18 boreholes were drilled to depths of 25 to 100 feet along three transects across the present floodplain. These borings provided data on the hydrogeologic character of the strata that fill the alluvial valley. The profiles from the borehole transects were compared with electrical conductivity (EM-34) data to ascertain the applicability of this geophysical technique to future investigations.

  6. Quantifying Flow Resistance in Rivers and on Floodplains During Large Floods

    NASA Astrophysics Data System (ADS)

    Kean, J. W.; Smith, J. D.

    2003-12-01

    In an effort to improve predictions of peak discharge at ungaged sites by reducing the uncertainty in estimates of channel roughness, a series of processed-based methods have been developed over the past several years to quantify the flow resistance of common channel roughness elements using simple measurements of their geometric properties. These methods have been recently incorporated into a flow model and have been applied to predict the velocity, discharge, and boundary shear stress in a 150-m densely vegetated reach of the Rock Creek Branch of the Whitewater River, Kansas. This is done without calibration using measured stage together with detailed measurements of the channel geometry and the size, shape, and spacings of the small-scale topographic features and plant stems in the channel. Topographic features on the bed and banks of the channel are characterized by a sequence of Gaussian shaped elements, which have drag coefficients known from recent experiments. Woody vegetation is modeled as randomly distributed rigid vertical cylinders. The model explicitly calculates drag on the roughness elements and includes the effects of friction on lateral boundaries on the flow and boundary shear stress. Model predictions of discharge during a moderate flow event are in agreement with the measured discharge at a USGS gaging station at the entrance to the study reach. The model is then used to explore the effect of floodplain roughness on the flow and boundary shear stress during a hypothetical overbank event. The model shows that drag on the vegetation substantially reduces the flow velocity on the floodplain, which results in increased velocities and boundary shear stress in the main portion of the channel relative to the case with no vegetation present. When used in conjunction with information on the critical shear stress of the bed and bank material, the model can be used to determine whether or not a given event can alter the channel topography and to evaluate

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

    SciTech Connect

    Rowland, Joel C; Dietrich, William E; Day, Geoff; Parker, Gary

    2009-01-01

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

  8. Formation and maintenance of single-thread tie channels entering floodplain lakes: Observations from three diverse river systems

    NASA Astrophysics Data System (ADS)

    Rowland, J. C.; Dietrich, W. E.; Day, G.; Parker, G.

    2009-06-01

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

  9. Using remote sensing data to assess salmon habitat status in rivers and floodplains of Puget Sound, USA

    NASA Astrophysics Data System (ADS)

    Beechie, T. J.; Pess, G. R.; Hall, J.; Timpane-Padgham, B.; Stefankiv, O.; Liermann, M. C.; Fresh, K.; Rowse, M.

    2015-12-01

    Natural processes create dynamic habitat features in large rivers and floodplains, and past land uses that restrict fluvial processes have altered habitat conditions in those environments in Puget Sound, USA. As a result, Chinook salmon and steelhead are listed as threatened species under the US Endangered Species Act (ESA). To help restore these salmon populations, restoration actions often focus on removing constraints on natural processes to restore fluvial dynamics and ultimately restore critical salmon habitats on floodplains. An important aspect of this restoration effort is monitoring whether habitat conditions are improving as anticipated, yet there are currently few protocols available for monitoring trends in large river and floodplain habitats. We identified several remote-sensing metrics that are indicators of salmon habitat condition, and developed repeatable protocols for measuring those metrics. We then tested their sensitivity to land use change by comparing habitat conditions among land cover classes (developed, agriculture, forested, and mixed). As expected, metrics of habitat complexity or condition such as side-channel length, node density, wood jam area, or riparian buffer widths were highest in forested sites and lowest in agriculture and urban sites. By contrast, percent disconnected floodplain and percent armored banks were highest in developed sites and lowest in forested sites. Our results indicate that remote sensing metrics are sensitive enough to detect differences in habitat status among land cover classes, and therefore help us understand the impact of various land uses on habitat conditions. However, detecting trends in habitat condition through time may be difficult because magnitudes of change through time are very small.

  10. Need for ecosystem management of large rivers and their floodplains: These phenomenally productive ecosystems produce fish and wildlife and preserve species

    SciTech Connect

    Sparks, R.E.

    1995-03-01

    Most of the 79 large river floodplain ecosystems in the world have been altered by human activities and the rest are likely to be altered soon. Ecosystem management works to guide rather than thwart, natural processes. This article describes briefly the history of floodplain and flood plain management and then focuses on the importance of large river-floodplain ecosystems and some of the consequences of altering the natural river processes, functions, and connectivity. The species-focused management system typically employed by natural resource agencies is contrasted to the ecosystem approach to river-flood plain management. Ecological management is defined as working with the natural driving forces and variability of the ecosystems with the goal of maintaining or recovering biological integrity. Flood-pulses are also a focus because they drive the system and the great floods on several continents in the last years. 88 refs., 10 figs.

  11. Combined effects of projected sea level rise, storm surge, and peak river flows on water levels in the Skagit Floodplain

    USGS Publications Warehouse

    Hamman, Josheph J; Hamlet, Alan F.; Fuller, Roger; Grossman, Eric

    2016-01-01

    Current understanding of the combined effects of sea level rise (SLR), storm surge, and changes in river flooding on near-coastal environments is very limited. This project uses a suite of numerical models to examine the combined effects of projected future climate change on flooding in the Skagit floodplain and estuary. Statistically and dynamically downscaled global climate model scenarios from the ECHAM-5 GCM were used as the climate forcings. Unregulated daily river flows were simulated using the VIC hydrology model, and regulated river flows were simulated using the SkagitSim reservoir operations model. Daily tidal anomalies (TA) were calculated using a regression approach based on ENSO and atmospheric pressure forcing simulated by the WRF regional climate model. A 2-D hydrodynamic model was used to estimate water surface elevations in the Skagit floodplain using resampled hourly hydrographs keyed to regulated daily flood flows produced by the reservoir simulation model, and tide predictions adjusted for SLR and TA. Combining peak annual TA with projected sea level rise, the historical (1970–1999) 100-yr peak high water level is exceeded essentially every year by the 2050s. The combination of projected sea level rise and larger floods by the 2080s yields both increased flood inundation area (+ 74%), and increased average water depth (+ 25 cm) in the Skagit floodplain during a 100-year flood. Adding sea level rise to the historical FEMA 100-year flood resulted in a 35% increase in inundation area by the 2040's, compared to a 57% increase when both SLR and projected changes in river flow were combined.

  12. Holocene environmental change inferred from the loess-palaeosol sequences adjacent to the floodplain of the Yellow River, China

    NASA Astrophysics Data System (ADS)

    Huang, Chun Chang; Pang, Jiangli; Su, Hongxia; Li, Shengli; Ge, Benwei

    2009-12-01

    Chinese loess deposits are generally considered to be the product of dust storms and dust falls from the central Asia arid zones that were transported across China by the northwesterly continental monsoon. In contrast, the Zhengzhou Loess found southeast of the Loess Plateau, adjacent to the floodplain of the Yellow River, records a different eolian regime and dust source. The Zhengzhou Loess was investigated by field observations, measurements of magnetic susceptibility, particle-size distribution, loss-on-ignition, CaCO 3 and chemical contents. Both field observations and the laboratory results indicate that, during the last glacial, the Zhengzhou Loess was supplied by two different eolian regimes and dust sources, one was from the fresh flood deposits of the Yellow River driven by the northeast winds from the low-lying floodplain, and the other was from the dust storms and dust falls that traveled across the Loess Plateau driven by the northwesterly continental monsoon from the central Asian arid lands. The early Holocene, 11,500-8500 a BP, was a transition during the change in eolian regime and dust source because of the weakened northwesterly monsoon along with the global climatic amelioration. Following the retreat of the northwesterly monsoon from the onset of the mid-Holocene Climatic Optimum at 8500 a BP, dust supply from the drifting sand zone on the Yellow River floodplain became dominant because of the intensified strength of the northeast winds from the Bohai Sea. From 3100 a BP onwards, climatic aridity and extensive human disturbance have resulted in intensive eolian processes causing the incursion of the drifting sand into the Zhengzhou Loess zone. These results show that loess accumulation is more complex than traditionally assumed. The origin of loess deposits elsewhere outside the Loess Plateau may be related to dust sources derived from alluvial sediments of major river systems.

  13. Polycyclic aromatic hydrocarbons in soil of the Canadian River floodplain in Oklahoma

    USGS Publications Warehouse

    Sartori, F.; Wade, T.L.; Sericano, J.L.; Mohanty, B.P.; Smith, K.A.

    2010-01-01

    The accumulation of polycyclic aromatic hydrocarbons (PAH) in soil, plants, and water may impart negative eff ects on ecosystem and human health. We quantified the concentration and distribution of 41 PAH (n = 32), organic C, total N, and S (n = 140) and investigated PAH sources using a chronosequence of floodplain soils under a natural vegetation succession. Soil samples were collected between 0- and 260-cm depth in bare land (the control), wetland, forest, and grassland areas near a closed municipal landfill and an active asphalt plant (the contaminant sources) in the north bank of the Canadian River near Norman, OK. Principal component, cluster, and correlation analyses were used to investigate the spatial distribution of PAH, in combination with diagnostic ratios to distinguish pyrogenic vs. petrogenic PAH suites. Total PAH concentration (??PAH) had a mean of 1300 ng g-1, minimum of 16 ng g-1, and maximum of 12,000 ng g-1. At 0- to 20-cm depth, ??PAH was 3500 ?? 1600 ng g-1 (mean ?? 1 SE) near the contaminant sources. The most common compounds were nonalkylated, high molecular weight PAH of pyrogenic origin, i.e., fluoranthene (17%), pyrene (14%), phenanthrene (9%), benzo(b)fluoranthene (7%), chrysene (6%), and benzo(a)anthracene (5%). ??PAH in the control (130 ?? 23 ng g -1) was comparable to reported concentrations for the rural Great Plains. Perylene had a unique distribution pattern suggesting biological inputs. The main PAH contamination mechanisms were likely atmospheric deposition due to asphalt production at the 0- to 20-cm depth and past landfill operations at deeper depths. Copyright ?? 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  14. Biogeochemical patchiness, geomorphic feedbacks, and flow connectivity in river-floodplain corridors

    NASA Astrophysics Data System (ADS)

    Larsen, L.; Harvey, J. W.; Maglio, M.

    2014-12-01

    redistribution are the dominant drivers of nutrient patchiness in the Everglades and are hypothesized to be important in P-limited river and floodplain corridors globally.

  15. Polycyclic aromatic hydrocarbons in soil of the Canadian river floodplain in Oklahoma.

    PubMed

    Sartori, Fabio; Wade, Terry L; Sericano, Jose L; Mohanty, Binayak P; Smith, Kevin A

    2010-01-01

    The accumulation of polycyclic aromatic hydrocarbons (PAH) in soil, plants, and water may impart negative effects on ecosystem and human health. We quantified the concentration and distribution of 41 PAH (n = 32), organic C, total N, and S (n = 140) and investigated PAH sources using a chronosequence of floodplain soils under a natural vegetation succession. Soil samples were collected between 0- and 260-cm depth in bare land (the control), wetland, forest, and grassland areas near a closed municipal landfill and an active asphalt plant (the contaminant sources) in the north bank of the Canadian River near Norman, OK. Principal component, cluster, and correlation analyses were used to investigate the spatial distribution of PAH, in combination with diagnostic ratios to distinguish pyrogenic vs. petrogenic PAH suites. Total PAH concentration (SigmaPAH) had a mean of 1300 ng g(-1), minimum of 16 ng g(-1), and maximum of 12,000 ng g(-1). At 0- to 20-cm depth, SigmaPAH was 3500 +/- 1600 ng g(-1) (mean +/- 1 SE) near the contaminant sources. The most common compounds were nonalkylated, high molecular weight PAH of pyrogenic origin, i.e., fluoranthene (17%), pyrene (14%), phenanthrene (9%), benzo(b)fluoranthene (7%), chrysene (6%), and benzo(a)anthracene (5%). SigmaPAH in the control (130 +/- 23 ng g(-1)) was comparable to reported concentrations for the rural Great Plains. Perylene had a unique distribution pattern suggesting biological inputs. The main PAH contamination mechanisms were likely atmospheric deposition due to asphalt production at the 0- to 20-cm depth and past landfill operations at deeper depths. PMID:20176830

  16. QMRAcatch - faecal microbial quality of water resources in a river-floodplain area affected by urban sources and recreational visitors

    NASA Astrophysics Data System (ADS)

    Derx, Julia; Schijven, Jack; Sommer, Regina; Kirschner, Alexander; Farnleitner, Andreas H.; Blaschke, Alfred Paul

    2016-04-01

    QMRAcatch, a tool to simulate microbial water quality including infection risk assessment, was previously developed and successfully tested at a Danube river site (Schijven et al. 2015). In the tool concentrations of target faecal microorganisms and viruses (TMVs) are computed at a point of interest (PI) along the main river and the floodplain river at daily intervals for a one year period. Even though faecal microbial pathogen concentrations in water resources are usually below the sample limit of detection, this does not ensure, that the water quality complies with a certain required health based target. The aim of this study was therefore to improve the predictability of relevant human pathogenic viruses, i.e. enterovirus and norovirus, in the studied river/floodplain area. This was done by following an innovative calibration strategy based on human-associated microbial source tracking (MST) marker data which were determined following the HF183 TaqMan assay (Green et al. 2011). The MST marker is strongly associated with human faeces and communal sewage, occurring there in numbers by several magnitudes higher than for human enteric pathogens (Mayer et al 2015). The calibrated tool was then evaluated with measured enterovirus concentrations at the PI and in the floodplain river. In the simulation tool the discharges of 5 wastewater treatment plants (WWTPs) were considered with point discharges along a 200 km reach of the Danube river. The MST marker and target virus concentrations at the PI at a certain day were computed based on the concentrations of the previous day, plus the wastewater concentrations times the WWTP discharge divided by the river discharge. A ratio of the river width was also considered, over which the MST marker and virus particles have fully mixed with river water. In the tool, the excrements from recreational visitors frequenting the floodplain area every day were assumed to be homogeneously distributed in the area. A binomial distributed

  17. QMRAcatch - faecal microbial quality of water resources in a river-floodplain area affected by urban sources and recreational visitors

    NASA Astrophysics Data System (ADS)

    Derx, Julia; Schijven, Jack; Sommer, Regina; Kirschner, Alexander; Farnleitner, Andreas H.; Blaschke, Alfred Paul

    2016-04-01

    QMRAcatch, a tool to simulate microbial water quality including infection risk assessment, was previously developed and successfully tested at a Danube river site (Schijven et al. 2015). In the tool concentrations of target faecal microorganisms and viruses (TMVs) are computed at a point of interest (PI) along the main river and the floodplain river at daily intervals for a one year period. Even though faecal microbial pathogen concentrations in water resources are usually below the sample limit of detection, this does not ensure, that the water quality complies with a certain required health based target. The aim of this study was therefore to improve the predictability of relevant human pathogenic viruses, i.e. enterovirus and norovirus, in the studied river/floodplain area. This was done by following an innovative calibration strategy based on human-associated microbial source tracking (MST) marker data which were determined following the HF183 TaqMan assay (Green et al. 2011). The MST marker is strongly associated with human faeces and communal sewage, occurring there in numbers by several magnitudes higher than for human enteric pathogens (Mayer et al 2015). The calibrated tool was then evaluated with measured enterovirus concentrations at the PI and in the floodplain river. In the simulation tool the discharges of 5 wastewater treatment plants (WWTPs) were considered with point discharges along a 200 km reach of the Danube river. The MST marker and target virus concentrations at the PI at a certain day were computed based on the concentrations of the previous day, plus the wastewater concentrations times the WWTP discharge divided by the river discharge. A ratio of the river width was also considered, over which the MST marker and virus particles have fully mixed with river water. In the tool, the excrements from recreational visitors frequenting the floodplain area every day were assumed to be homogeneously distributed in the area. A binomial distributed

  18. Geomorphic and hydrologic assessment of erosion hazards at the Norman municipal landfill, Canadian River floodplain, Central Oklahoma

    USGS Publications Warehouse

    Curtis, J.A.; Whitney, J.W.

    2003-01-01

    The Norman, Oklahoma, municipal landfill closed in 1985 after 63 years of operation, because it was identified as a point source of hazardous leachate composed of organic and inorganic compounds. The landfill is located on the floodplain of the Canadian River, a sand-bed river characterized by erodible channel boundaries and by large variation in mean monthly discharges. In 1986, floodwaters eroded riprap protection at the southern end of the landfill and penetrated the landfill's clay cap, thereby exposing the landfill contents. The impact of this moderate-magnitude flood event (Q12) was the catalyst to investigate erosion hazards at the Norman landfill. This geomorphic investigation analyzed floodplain geomorphology and historical channel changes, flood-frequency distributions, an erosion threshold, the geomorphic effectiveness of discharge events, and other factors that influence erosion hazards at the landfill site. The erosion hazard at the Norman landfill is a function of the location of the landfill with respect to the channel thalweg, erosional resistance of the channel margins, magnitude and duration of discrete discharge events, channel form and hydraulic geometry, and cumulative effects related to a series of discharge events. Based on current climatic conditions and historical channel changes, a minimum erosion threshold is set at bankfull discharge (Q = 572 m3/s). The annual probability of exceeding this threshold is 0.53. In addition, this analysis indicates that peak stream power is less informative than total energy expenditures when estimating the erosion potential or geomorphic effectiveness of discrete discharge events. On the Canadian River, long-duration, moderate-magnitude floods can have larger total energy expenditures than shorter-duration, high-magnitude floods and therefore represent the most serious erosion hazard to floodplain structures.

  19. Deposition and storage of solid-bound heavy metals in the floodplains of the River Geul (the Netherlands).

    PubMed

    Leenaers, H

    1991-08-01

    Because of past mining activities, the floodplains of the River Geul are polluted with heavy metals. The continuous supply of fresh sediments during floods has caused the floodplain soils to exhibit large quality variations in time. By measurements of (137)Cs deposition rates in part of the floodplain area were determined at 0.4 to 2.7 cm yr(-1). Analysis of soil metal concentrations at various depths at 65 locations, revealed that the upper 40 cm of the soil profile deposited during the past 30-45 yr, exhibit the highest metal levels. The geostatistical interpolation technique kriging was used to map actual and past pollution patterns. It was shown that, as a result of variable deposition rates, the spatial correlation structure of soil metal concentrations becomes less clear with increasing depth/age. Kriged maps of average metal concentrations in the upper 100 cm of the soil profile provided the basis for the calculation of the mass storage of heavy metals.

  20. Effects of flooding on ion exchange rates in an Upper Mississippi River floodplain forest impacted by herbivory, invasion, and restoration

    USGS Publications Warehouse

    Kreiling, Rebecca; DeJager, Nathan R.; Whitney Swanson,; Eric A. Strauss,; Meredith Thomsen,

    2015-01-01

    We examined effects of flooding on supply rates of 14 nutrients in floodplain areas invaded by Phalaris arundinacea (reed canarygrass), areas restored to young successional forests (browsed by white-tailed deer and unbrowsed), and remnant mature forests in the Upper Mississippi River floodplain. Plant Root Simulator ion-exchange probes were deployed for four separate 28-day periods. The first deployment occurred during flooded conditions, while the three subsequent deployments were conducted during progressively drier periods. Time after flooding corresponded with increases in NO3 −-N, K+ and Zn+2, decreases in H2PO4 −-P, Fe+3, Mn+2, and B(OH)4-B, a decrease followed by an increase in NH4 +-N, Ca+2, Mg+2 and Al+3, and an increase followed by a decrease for SO4 −2-S. Plant community type had weak to no effects on nutrient supply rates compared to the stronger effects of flooding duration. Our results suggest that seasonal dynamics in floodplain nutrient availability are similarly driven by flood pulses in different community types. However, reed canarygrass invasion has potential to increase availability of some nutrients, while restoration of forest cover may promote recovery of nutrient availability to that observed in reference mature forests.

  1. Location and description of transects for ecological studies in floodplain forests of the lower Suwannee River, Florida

    USGS Publications Warehouse

    Lewis, L.J.; Light, H.M.; Darst, M.R.

    2001-01-01

    Twelve transects were established in floodplain forests along the lower Suwannee River, Florida, as the principal data collection sites for a comprehensive study conducted by the U.S. Geological Survey and the Suwannee River Water Management District from 1996 to 2001. Data collected along the 12 transects included hydrologic conditions, land-surface elevations, soils, and vegetation of floodplain forests in relation to river flow. Transect locations are marked in the field with permanent markers at approximately 30 meter intervals. Detailed descriptions of the 12 transects and their locations are provided so that they can be used for future ecological studies. Descriptions of the transects include contact information necessary for access to the property on which the transects are located, maps showing transect locations and routes from the nearest city or major road, small scale maps of each transect showing marker locations, latitude and longitude of each marker, compass bearings of each transect line and graphs showing land-surface elevations of the transect with marker locations.

  2. Evaluating Effects of Floodplain Constriction Along a High Energy Gravel-Bed River: Snake River, WY

    NASA Astrophysics Data System (ADS)

    Leonard, Christina M.

    This study examined approximately 66 km of the Snake River, WY, USA, spanning a natural reach within Grand Teton National Park and a reach immediately downstream that is confined by artificial levees. We linked the channel adjustments observed within these two reaches between 2007 and 2012 to sediment transport processes by developing a morphological sediment budget. A pair of digital elevation models (DEMs) was generated by fusing LiDAR topography with depth estimates derived from optical image data within wetted channels. Errors for both components of the DEMs (LiDAR and optical bathymetry) were propagated through the DEM of difference and sediment budget calculations. Our results indicated that even with the best available methods for acquiring high resolution topographic data over large areas, the uncertainty associated with bed elevation estimates implied that net volumetric changes were not statistically significant. In addition to the terrain analysis, we performed a tracer study to assess the mobility of different grain size classes in different morphological units. Grain sizes, hydraulic conditions, and flow resistance characteristics along cross-sections were used to calculate critical discharges for entrainment, but this bulk characterization of fluid driving forces failed to predict bed mobility. Our results indicated that over seasonal timescales specific grain classes were not preferentially entrained. Surface and subsurface grain size data were used to calculate armoring and dimensionless sediment transport ratios for both reaches; sediment supply exceeded transport capacity in the natural reach and vice versa in the confined reach. We used a conceptual model to describe channel adjustments to lateral constriction by levees. Initially we suggest levees focused flow energy and incised the bed, resulting in bed armoring. Bed armoring promoted channel widening, but levees prevented this and instead the channel migrated more rapidly within the

  3. pCO2 and enzymatic activity in a river floodplain system of the Danube under different hydrological settings.

    NASA Astrophysics Data System (ADS)

    Sieczko, Anna; Demeter, Katalin; Mayr, Magdalena; Meisterl, Karin; Peduzzi, Peter

    2014-05-01

    Surface waters may serve as either sinks or sources of CO2. In contrast to rivers, which are typically sources of CO2 to the atmosphere, the role of fringing floodplains in CO2 flux is largely understudied. This study was conducted in a river-floodplain system near Vienna (Austria). The sampling focused on changing hydrological situations, particularly on two distinct flood events: a typical 1-year flood in 2012 and an extraordinary 100-year flood in 2013. One objective was to determine partial pressure of CO2 (pCO2) in floodplain lakes with different degree of connectivity to the main channel, and compare the impact of these two types of floods. Another aim was to decipher which fraction of the dissolved organic matter (DOM) pool contributed to pCO2 by linking pCO2 with optical properties of DOM and extracellular enzymatic activity (EEA) of microbes. The EEA is a valuable tool, especially for assessing the non-chromophoric but rapidly utilized DOM-fraction during floods. In 2012 and 2013, the floodplain lakes were dominated by supersaturated pCO2 conditions, which indicates that they served as CO2 sources. Surprisingly, there were no significant differences in pCO2 between the two types of flood. Our findings imply that the extent of the flood had minor impact on pCO2, but the general occurrence of a flood appears to be important. During the flood in 2013 significantly more dissolved organic carbon (DOC) (p<0.05) was introduced into the floodplain. The optical measurements pointed towards more refractory DOM, with higher molecular weight and humic content during the flood in 2013 compared to 2012. However there were no significant differences in EEA between the two floods. Few days after beginning of the floods in 2012 and 2013, an increase in activity of carbon-acquiring enzymes (EEA-C) was observed. We also found positive correlations of pCO2with EEA-C both in 2012 (r=0.86, p<0.01) and in 2013 (r=0.73, p<0.05). The above findings imply that some fraction of DOM

  4. Late Holocene development of a major fluvial discontinuity in floodplain wetlands of the Blood River, eastern South Africa

    NASA Astrophysics Data System (ADS)

    Tooth, Stephen; McCarthy, Terence; Rodnight, Helena; Keen-Zebert, Amanda; Rowberry, Matthew; Brandt, Dion

    2014-01-01

    In dryland settings, most floodplain wetlands form in low gradient, low energy environments that are characterised by strong interactions between flow, sediment and biota. Some floodplain wetlands are only partly channelled or largely unchannelled, and represent major discontinuities in drainage networks, fundamentally influencing downvalley water and sediment transfer. In the > 15 km2 Blood River floodplain wetlands, located in subhumid to semiarid eastern South Africa, field investigations, aerial photographs, and optically stimulated luminescence (OSL) ages provide evidence for development of a major discontinuity during the very late Holocene. Between ~ 800 and 100 years ago, the wetlands were characterised by a through-going, meandering channel set within a floodplain up to 2.5 km wide. A sinuous channel remains in the lower part of the wetlands but during the last ~ 100 years major morphological and sedimentary changes have occurred upvalley. The former through-going, meandering channel has been replaced by a straighter channel that decreases in size downstream and terminates in a 'floodout', characterised here by an unchannelled reedbed. Small tributaries supply water and limited sediment to this floodout and another floodout located farther downvalley. Organo-clastic sediments > 3 m thick have accumulated in the floodouts as broad lobes, in places burying the former meander-belt sediments. On the steepened, downvalley sides of these lobes, small headcutting channels convey water that filters through the reedbeds. If headcutting through the lobes continues, a through-going channel may re-establish upvalley, possibly eventually linking with the sinuous but now moribund channel in the lower part of the wetlands. Along the Blood River, the initial cause(s) of the sequence of changes is not known, but these channel-floodplain adjustments are partially analogous to the system-scale, autogenic morphological and sedimentary dynamics of those dryland fluvial systems

  5. Water-level decline in the Apalachicola River, Florida, from 1954 to 2004, and effects on floodplain habitats

    USGS Publications Warehouse

    Light, Helen M.; Vincent, Kirk R.; Darst, Melanie R.; Price, Franklin D.

    2006-01-01

    downstream limit of the influence of the dam on bed scour. Downstream from that location, previously unreported water-level declines progressively increased to 3 feet at a location 68 miles downstream from the dam, probably as a result of various channel modifications conducted in that part of the river. Water-level declines in the river have substantially changed long-term hydrologic conditions in more than 200 miles of off-channel floodplain sloughs, streams, and lakes and in most of the 82,200 acres of floodplain forests in the nontidal reach of the Apalachicola River. Decreases in duration of floodplain inundation at low discharges were large in the upstream-most 10 miles of the river (20-45 percent) and throughout most of the remaining 75 miles of the nontidal reach (10-25 percent). As a consequence of this decreased inundation, the quantity and quality of floodplain habitats for fish, mussels, and other aquatic organisms have declined, and wetland forests of the floodplain are changing in response to drier conditions. Water-level decline caused by channel change is probably the most serious anthropogenic impact that has occurred so far in the Apalachicola River and floodplain. This decline has been exacerbated by long-term reductions in spring and summer flow, especially during drought periods. Although no trends in total annual flow volumes were detected, long-term decreases in discharge for April, May, July, and August were apparent, and water-level declines during drought conditions resulting from decreased discharge in those 4 months were similar in magnitude to the water-level declines caused by channel changes. The observed changes in seasonal discharge are probably caused by a combination of natural climatic changes and anthropogenic activities in the Apalachicola-Chattahoochee-Flint River Basin. Continued research is needed for geomorphic studies to assist in the design of future floodplain restoration efforts and for hydrologic studies to monitor change

  6. Delineating forested river habitats and riparian floodplain hydrology with LiDAR

    NASA Astrophysics Data System (ADS)

    Vondrasek, Chris

    Rivers and the riparian forest corridor comprise a valuable freshwater ecosystem that has been altered by human activities including timber management, road building, and other land conversions. The habitats of river dependent species in the Pacific Northwest, in particular salmon have often been degraded by these activities. Many salmon runs have become threatened with extinction and have been Endangered Species Act listed. New conservation planning and policies have developed around protecting freshwater habitats and restoring more natural river processes. In WA State, timber landowners, officials from State and Federal agencies, Native tribes, and other stakeholders developed Forest Practice rules and codified a Habitat Conservation Plan with dual goals of providing regulatory surety for timber land owners and helping to recover the threatened salmon runs in forested watersheds. Conserving critical stream ecological functions and potential fish habitats throughout watersheds while managing and regulating timber harvest across the State requires accurate and up-to-date delineation and mapping of channels, tributaries, and off-channel wetlands. Monitoring the effectiveness of protection efforts is necessary but can also be difficult. Agency staff and resources are limited for both day-to-day implementation of Forest Practice rules and adaptive management. The goal of this research has been to develop efficient and accessible methods to delineate wetlands, side-channels, tributaries, and pools and backwaters created by large log jams in forested watersheds. It was also essential to use publicly available LiDAR data and to model these waters at ecologically meaningful flows. I tested a hydraulic model at a 2-year and 50-year flows, and a relative height above river surface model and compared them. I completed two additional remote sensing investigations to correlate channel movement and the locations of off-channel wetlands: an analysis of historical aerial imagery

  7. Geospatial assessment of ecological functions and flood-related risks on floodplains along major rivers in the Puget Sound Basin, Washington

    USGS Publications Warehouse

    Konrad, Christopher P.

    2015-01-01

    Ecological functions and flood-related risks were assessed for floodplains along the 17 major rivers flowing into Puget Sound Basin, Washington. The assessment addresses five ecological functions, five components of flood-related risks at two spatial resolutions—fine and coarse. The fine-resolution assessment compiled spatial attributes of floodplains from existing, publically available sources and integrated the attributes into 10-meter rasters for each function, hazard, or exposure. The raster values generally represent different types of floodplains with regard to each function, hazard, or exposure rather than the degree of function, hazard, or exposure. The coarse-resolution assessment tabulates attributes from the fine-resolution assessment for larger floodplain units, which are floodplains associated with 0.1 to 21-kilometer long segments of major rivers. The coarse-resolution assessment also derives indices that can be used to compare function or risk among different floodplain units and to develop normative (based on observed distributions) standards. The products of the assessment are available online as geospatial datasets (Konrad, 2015; http://dx.doi.org/10.5066/F7DR2SJC).

  8. Late Holocene chronology and geomorphic development of fluvial-tidal floodplains in the upper reaches of the lower Columbia River Valley, Washington and Oregon, USA

    NASA Astrophysics Data System (ADS)

    Peterson, Curt D.; Roberts, Michael C.; Vanderburgh, Sandy; Minor, Rick; Percy, David

    2014-01-01

    The upper reaches of the lower Columbia River Valley (125 km in length) comprise an alluvial system that is transitional between fluvial and fluvial-tidal dominance. Sinuous channels separate elongate islands (1-8 km in length) and floodplains (0.5-12.7 km in total width). Thirty-six floodplain overbank deposits are analyzed for age and depth, which demonstrate an average sedimentation rate of 1.6 m ka- 1 during the last 5-6 ka. Older core records confirm that long-term depositional rates are controlled by relative sea level rise. Rising floodplain groundwater surfaces, which followed relative sea level rise (~ 1.25 m ka- 1), submerged isolated floodplain depressions. Low sedimentation rates in the isolated depressions (0.6-1.1 m ka- 1) maintained large ellipsoidal bullseye lakes (7-22 km2 in area) dating back to 3.5-4.0 ka. Increases in the widths of the floodplains and bullseye lakes are associated with broadening of the incised valley (4-13 km width) in the Portland Basin. Dated basal overbank deposits (0.5-5.0 ka in age) and their separation distances establish channel migration rates of 0.3-1.9 km ka- 1. Shallow burial rates relative to rapid channel migration rates resulted in reworking of late Holocene floodplains (50-75% erosion) since 5 ka in the upper reaches of the lower Columbia River Valley.

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

    USGS Publications Warehouse

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

    2010-01-01

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

  10. Geomorphic and vegetation processes of the Willamette River floodplain, Oregon: current understanding and unanswered science questions

    USGS Publications Warehouse

    Wallick, J. Rose; Jones, Krista L.; O'Connor, Jim E.; Keith, Mackenzie K.; Hulse, David; Gregory, Stanley V.

    2013-01-01

    4. How is the succession of native floodplain vegetation shaped by present-day flow and sediment conditions? Answering these questions will produce baseline data on the current distributions of landforms and habitats (question 1), the extent of the functional floodplain (question 2), and the effects of modern flow and sediment regimes on future floodplain landforms, habitats, and vegetation succession (questions 3 and 4). Addressing questions 1 and 2 is a logical next step because they underlie questions 3 and 4. Addressing these four questions would better characterize the modern Willamette Basin and help in implementing and setting realistic targets for ongoing management strategies, demonstrating their effectiveness at the site and basin scales, and anticipating future trends and conditions.

  11. [Vertical structure of bacterial communities in peats of the Yakhroma River floodplain].

    PubMed

    Dobrovol'skaia, T G; Golovchenko, A V; Pozdniakov, A I

    2007-01-01

    The abundance and taxonomic structure of soil bacterial communities have been studied in different geomorphological parts of the Yakhroma floodplain. It has been found that the numbers of bacteria reach a peak in calcareous peat soil under forest near the floodplain terrace, decreasing to a minimum in soddy alluvial soil near the riverbed. All soils are characterized by the presence of different ecological-trophic bacterial groups capable of peat destruction. Seasonal dynamics of the structure of bacterial communities and, in some soil types, its spatial dynamics accounted for by changes in the botanical structure of peat across its profile have been revealed. All peat soils in the floodplain have high contents of organic matter and neutral pH and, therefore, are favorable biotopes for the development of saprotrophic bacteria. This, in turn, largely accounts for high productivity and stability of this agroecosystem as a whole.

  12. [Vertical structure of bacterial communities in peats of the Yakhroma River floodplain].

    PubMed

    Dobrovol'skaia, T G; Golovchenko, A V; Pozdniakov, A I

    2007-01-01

    The abundance and taxonomic structure of soil bacterial communities have been studied in different geomorphological parts of the Yakhroma floodplain. It has been found that the numbers of bacteria reach a peak in calcareous peat soil under forest near the floodplain terrace, decreasing to a minimum in soddy alluvial soil near the riverbed. All soils are characterized by the presence of different ecological-trophic bacterial groups capable of peat destruction. Seasonal dynamics of the structure of bacterial communities and, in some soil types, its spatial dynamics accounted for by changes in the botanical structure of peat across its profile have been revealed. All peat soils in the floodplain have high contents of organic matter and neutral pH and, therefore, are favorable biotopes for the development of saprotrophic bacteria. This, in turn, largely accounts for high productivity and stability of this agroecosystem as a whole. PMID:18038631

  13. Projecting avian response to linked changes in groundwater and riparian floodplain vegetation along a dryland river: A scenario analysis

    USGS Publications Warehouse

    Arriana, Brand L.; Stromberg, J.C.; Goodrich, D.C.; Dixon, M.D.; Lansey, K.; Kang, D.; Brookshire, D.S.; Cerasale, D.J.

    2011-01-01

    Groundwater is a key driver of riparian condition on dryland rivers but is in high demand for municipal, industrial, and agricultural uses. Approaches are needed to guide decisions that balance human water needs while conserving riparian ecosystems. We developed a space-for-time substitution model that links groundwater change scenarios implemented within a Decision Support System (DSS) with proportions of floodplain vegetation types and abundances of breeding and migratory birds along the upper San Pedro River, AZ, USA. We investigated nine scenarios ranging from groundwater depletion to recharge. In groundwater decline scenarios, relative proportions of tall-canopied obligate phreatophytes (Populus/Salix, cottonwood/willow) on the floodplain progressively decline, and shrubbier species less dependent on permanent water sources (e.g. Tamarix spp., saltcedar) increase. These scenarios result in broad shifts in the composition of the breeding bird community, with canopy-nesting and water-obligate birds declining but midstory nesting birds increasing in abundance as groundwater declines. For the most extreme draw-down scenario where all reaches undergo groundwater declines, models project that only 10% of the upper San Pedro floodplain would be comprised of cottonwood/willow (73% saltcedar and 18% mesquite), and abundances of canopy-nesting, water-obligate, and spring migrant birds would decline 48%, 72%, and 40%, respectively. Groundwater recharge scenarios were associated with increases in canopy-nesting birds particularly given the extreme recharge scenario (all reaches regain shallow water tables and perennial streamflow). Model outputs serve to assess the sensitivity of biotic groups to potential changes in groundwater and thus to rank scenarios based on their expected ecological impacts. ?? 2010 John Wiley & Sons, Ltd.

  14. Water uptake and nutrient concentrations under a floodplain oak savanna during a non-flood period, lower Cedar River, Iowa

    USGS Publications Warehouse

    Schilling, K.E.; Jacobson, P.

    2009-01-01

    Floodplains during non-flood periods are less well documented than when flooding occurs, but non-flood periods offer opportunities to investigate vegetation controls on water and nutrient cycling. In this study, we characterized water uptake and nutrient concentration patterns from 2005 to 2007 under an oak savanna located on the floodplain of the Cedar River in Muscatine County, Iowa. The water table ranged from 0.5 to 2.5 m below ground surface and fluctuated in response to stream stage, plant water demand and rainfall inputs. Applying the White method to diurnal water table fluctuations, daily ET from groundwater averaged more than 3.5 mm/day in June and July and approximately 2 mm/day in May and August. Total annual ET averaged 404 mm for a growing season from mid-May to mid-October. Savanna groundwater concentrations of nitrate-N, ammonium-N, and phosphate-P were very low (mean <0.18, <0.14, <0.08 mg/l, respectively), whereas DOC concentrations were high (7.1 mg/l). Low concentrations of N and P were in contrast to high nutrient concentrations in the nearby Cedar River, where N and P averaged 7.5 mg/ l and 0.13, respectively. In regions dominated by intensive agriculture, study results document valuable ecosystem services for native floodplain ecosystems in reducing watershed-scale nutrient losses and providing an oasis for biological complexity. Improved understanding of the environmental conditions of regionally significant habitats, including major controls on water table elevations and water quality, offers promise for better management aimed at preserving the ecology of these important habitats. Copyright ?? 2009 John Wiley & Sons, Ltd.

  15. How livestock and flooding mediate the ecological integrity of working forests in Amazon River floodplains.

    PubMed

    Lucas, Christine M; Sheikh, Pervaze; Gagnon, Paul R; Mcgrath, David G

    2016-01-01

    The contribution of working forests to tropical conservation and development depends upon the maintenance of ecological integrity under ongoing land use. Assessment of ecological integrity requires an understanding of the structure, composition, and function and major drivers that govern their variability. Working forests in tropical river floodplains provide many goods and services, yet the data on the ecological processes that sustain these services is scant. In flooded forests of riverside Amazonian communities, we established 46 0.1-ha plots varying in flood duration, use by cattle and water buffalo, and time since agricultural abandonment (30-90 yr). We monitored three aspects of ecological integrity (stand structure, species composition, and dynamics of trees and seedlings) to evaluate the impacts of different trajectories of livestock activity (alleviation, stasis, and intensification) over nine years. Negative effects of livestock intensification were solely evident in the forest understory, and plots alleviated from past heavy disturbance increased in seedling density but had higher abundance of thorny species than plots maintaining low activity. Stand structure, dynamics, and tree species composition were strongly influenced by the natural pulse of seasonal floods, such that the defining characteristics of integrity were dependent upon flood duration (3-200 d). Forests with prolonged floods ≥ 140 d had not only lower species richness but also lower rates of recruitment and species turnover relative to forests with short floods <70 d. Overall, the combined effects of livestock intensification and prolonged flooding hindered forest regeneration, but overall forest integrity was largely related to the hydrological regime and age. Given this disjunction between factors mediating canopy and understory integrity, we present a subset of metrics for regeneration and recruitment to distinguish forest condition by livestock trajectory. Although our study design

  16. How livestock and flooding mediate the ecological integrity of working forests in Amazon River floodplains.

    PubMed

    Lucas, Christine M; Sheikh, Pervaze; Gagnon, Paul R; Mcgrath, David G

    2016-01-01

    The contribution of working forests to tropical conservation and development depends upon the maintenance of ecological integrity under ongoing land use. Assessment of ecological integrity requires an understanding of the structure, composition, and function and major drivers that govern their variability. Working forests in tropical river floodplains provide many goods and services, yet the data on the ecological processes that sustain these services is scant. In flooded forests of riverside Amazonian communities, we established 46 0.1-ha plots varying in flood duration, use by cattle and water buffalo, and time since agricultural abandonment (30-90 yr). We monitored three aspects of ecological integrity (stand structure, species composition, and dynamics of trees and seedlings) to evaluate the impacts of different trajectories of livestock activity (alleviation, stasis, and intensification) over nine years. Negative effects of livestock intensification were solely evident in the forest understory, and plots alleviated from past heavy disturbance increased in seedling density but had higher abundance of thorny species than plots maintaining low activity. Stand structure, dynamics, and tree species composition were strongly influenced by the natural pulse of seasonal floods, such that the defining characteristics of integrity were dependent upon flood duration (3-200 d). Forests with prolonged floods ≥ 140 d had not only lower species richness but also lower rates of recruitment and species turnover relative to forests with short floods <70 d. Overall, the combined effects of livestock intensification and prolonged flooding hindered forest regeneration, but overall forest integrity was largely related to the hydrological regime and age. Given this disjunction between factors mediating canopy and understory integrity, we present a subset of metrics for regeneration and recruitment to distinguish forest condition by livestock trajectory. Although our study design

  17. Numerical Model for Channel/Floodplain Exchange on a Gravel Bed River: Relative Importance of Upstream and Downstream Boundaries and of Lateral Exchange (Invited)

    NASA Astrophysics Data System (ADS)

    Lauer, J. W.

    2013-12-01

    The centennial-scale evolution of a meandering gravel-bed river has been represented using a size-specific 1-D sediment transport model. The model differs from other 1-D morphodynamic models for gravel-bed rivers in that it allows for sediment storage in and remobilization from an off-channel sediment storage reservoir representing the floodplain. Hydraulics is represented using a 1-D gradually varied flow model that assumes a rectangular cross-section for the channel zone and a constant elevation for the floodplain. Because the solution for steady uniform flow is necessarily iterative in this framework, the gradually varied hydraulic model is not significantly more computationally intensive than is a normal flow solution. The model is parameterized primarily based on the assumption that the channel creates point bars at a constant elevation above the bed. Bar progradation rate is assumed equal to a specified lateral migration rate (which can vary as a function of sediment load). The return of sediment from floodplain to channel is assumed equal to the lateral migration rate times the average bank elevation. Any net imbalance in sediment storage within the floodplain zone results in a change in average elevation and size distribution for the floodplain. This in turn affects the partition of flow between channel and floodplain and the net flux of sediment from the floodplain to channel, eventually causing the model to evolve toward a steady state bankfull capacity. The model is applied to the Ain River, France, a tributary of the Rhône River. The Ain River underwent significant geomorphic transformations over the course of the 20th century in response to changes in climate, vegetation, floodplain management, and, especially, because of the installation of a series of hydroelectric dams. In general, the channel became more incised and less laterally active during this period. However, bank erosion and sediment deposition in bars and floodplain channels continues to

  18. Understory vegetation as an indicator for floodplain forest restoration in the Mississippi River Alluvial Valley, U.S.A.

    USGS Publications Warehouse

    De Steven, Diane; Faulkner, Stephen; Keeland, Bobby D.; Baldwin, Michael; McCoy, John W.; Hughes, Steven C.

    2015-01-01

    In the Mississippi River Alluvial Valley (MAV), complete alteration of river-floodplain hydrology allowed for widespreadconversion of forested bottomlands to intensive agriculture, resulting in nearly 80% forest loss. Governmental programs haveattempted to restore forest habitat and functions within this altered landscape by the methods of tree planting (afforestation)and local hydrologic enhancement on reclaimed croplands. Early assessments identified factors that influenced whetherplanting plus tree colonization could establish an overstory community similar to natural bottomland forests. The extentto which afforested sites develop typical understory vegetation has not been evaluated, yet understory composition may beindicative of restored site conditions. As part of a broad study quantifying the ecosystem services gained from restorationefforts, understory vegetation was compared between 37 afforested sites and 26 mature forest sites. Differences in vegetationattributes for species growth forms, wetland indicator classes, and native status were tested with univariate analyses;floristic composition data were analyzed by multivariate techniques. Understory vegetation of restoration sites was generallyhydrophytic, but species composition differed from that of mature bottomland forest because of young successional age anddiffering responses of plant growth forms. Attribute and floristic variation among restoration sites was related to variationin canopy development and local wetness conditions, which in turn reflected both intrinsic site features and outcomes ofrestoration practices. Thus, understory vegetation is a useful indicator of functional progress in floodplain forest restoration.

  19. Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River Basin

    NASA Astrophysics Data System (ADS)

    Zuijdgeest, A. L.; Zurbrügg, R.; Blank, N.; Fulcri, R.; Senn, D. B.; Wehrli, B.

    2015-07-01

    Floodplains are important biogeochemical reactors during fluvial transport of carbon and nutrient species towards the oceans. In the tropics and subtropics pronounced rainfall seasonality results in highly dynamic floodplain biogeochemistry. Massive construction of hydropower dams, however, has significantly altered the hydrography and chemical characteristics of many (sub)tropical rivers. In this study, we compare organic matter and nutrient biogeochemistry of two large, contrasting floodplains in the Zambezi River Basin in Southern Africa, the Barotse Plains and the Kafue Flats. Both systems are of comparable size, but differ in anthropogenic influence: while the Barotse Plains are still relatively pristine, the Kafue Flats are bordered by two hydropower dams. While the Barotse Plains retain particles during the wet season, annual yields of particulate organic carbon and nitrogen are higher than previously reported for the Zambezi and other tropical rivers. Enhanced wet-season runoff adds soil-derived dissolved organic carbon and nitrogen to the Zambezi River, with a corresponding increase in the Barotse Plains. Soil-derived organic matter dominates the particulate phase year-round in the Barotse Plains, and a varying influence of C3- and C4-plant vegetation can be observed throughout the year. In contrast to the Barotse Plains, net export of particulate matter from the Kafue Flats has been observed during the wet season, but over an annual cycle, the Kafue Flats are effectively accumulating dissolved carbon and nutrients. In the Kafue Flats, the runoff-induced increase in dissolved organic carbon and nitrogen concentrations is delayed by the upstream dam operation. The dam reservoir also causes a shift in the source of the particulate organic matter - from soil-derived during the dry season to aquatically produced in the wet season - in the downstream Kafue Flats. Spatial zonation in vegetation and temporal flooding dynamics in the Kafue Flats result in mostly C

  20. Limnology in the Upper Paraná River floodplain: large-scale spatial and temporal patterns, and the influence of reservoirs.

    PubMed

    Roberto, M C; Santana, N N; Thomaz, S M

    2009-06-01

    Knowledge of abiotic limnological factors is important to monitor changes caused by humans, and to explain the structure and dynamics of populations and communities in a variety of inland water ecosystems. In this study, we used a long term data-set (eight years) collected in 10 habitats with different features (river channels, and connected and isolated lakes) to describe the spatial and temporal patterns of some of the principal limnological factors. In general, the degree of connectivity of the lakes, together with the rivers to which the lakes are connected, were important determinants of their limnological characteristics. These differences are expected, because rivers entering the floodplain come from different geological regions and are subject to different human impacts. At large spatial scales, these differences contribute to the increased habitat diversity of the floodplain and thus to its high biodiversity. With regard to temporal variation, Secchi-disk transparency increased, and total phosphorus decreased in the Paraná River main channel during the last 20 years. Although these changes are directly attributed to the several reservoir cascades located upstream, the closing of the Porto Primavera dam in 1998 enhanced this effect. The increase in water transparency explains biotic changes within the floodplain. The lower-phosphorus Paraná River water probably dilutes concentrations of this element in the floodplain waterbodies during major floods, with future consequences for their productivity.

  1. Treating floodplain lakes of large rivers as study units for variables that vary within lakes; an evaluation using chlorophyll a and inorganic suspended solids data from floodplain lakes of the Upper Mississippi River

    USGS Publications Warehouse

    Gray, B.R.; Rogala, J.R.; Houser, J.N.

    2013-01-01

    Contiguous floodplain lakes ('lakes') have historically been used as study units for comparative studies of limnological variables that vary within lakes. The hierarchical nature of these studies implies that study variables may be correlated within lakes and that covariate associations may differ not only among lakes but also by spatial scale. We evaluated the utility of treating lakes as study units for limnological variables that vary within lakes based on the criteria of important levels of among-lake variation in study variables and the observation of covariate associations that vary among lakes. These concerns were selected, respectively, to ensure that lake signatures were distinguishable from within-lake variation and that lake-scale effects on covariate associations might provide inferences not available by ignoring those effects. Study data represented chlorophyll a (CHL) and inorganic suspended solids (ISS) data from lakes within three reaches of the Upper Mississippi River. Sampling occurred in summer from 1993 through 2005 (except 2003); numbers of lakes per reach varied from 7 to 19, and median lake area varied from 53 to 101 ha. CHL and ISS levels were modelled linearly, with lake, year and lake x year effects treated as random. For all reaches, the proportions of variation in CHL and ISS attributable to differences among lakes (including lake and lake x year effects) were substantial (range: 18%-73%). Finally, among-lake variation in CHL and ISS was strongly associated with covariates and covariate effects that varied by lakes or lake-years (including with vegetation levels and, for CHL, log(ISS)). These findings demonstrate the utility of treating floodplain lakes as study units for the study of limnological variables and the importance of addressing hierarchy within study designs when making inferences from data collected within floodplain lakes.

  2. Flood-plain areas of the Mississippi River, mile 866.8 to mile 888.0, Minnesota

    USGS Publications Warehouse

    Carlson, George H.; Gue, Lowell C.

    1980-01-01

    Profiles of the regional flood, 500-year flood, and flood-protection elevation have been developed for a 21-mile reach of the Mississippi River. Areas flooded by the regional flood and by the 500-year flood were delineated by photogrammetric mapping techniques and are shown on seven large-scale map sheets. Over 1,300 acres of flood plain are included in the cities of Anoka, Champlin, Coon Rapids, Dayton, Ramsey and Elk River, and in unincorporated areas of Wright County. The flood-outline maps and flood profiles comprise data needed by local units of government to adopt, enforce, and administer flood-plain management regulations along the Mississippi River throughout the study reach. Streamflow data from two gaging stations provided the basis for definition of the regional and 500-year floods. Cross-section data obtained at 83 locations were used to develop a digital computer model of the river. Flood elevation and discharge data from the 1965 flood provided a basis for adjusting the computer model. Information relating the history of floods, formation of ice jams, and duration of flood elevations at Anoka and at Elk River are included.

  3. A coupled monitoring network to conduct an assessment of mercury transformation and mobilization in floodplain soils: South River, Virginia

    NASA Astrophysics Data System (ADS)

    Lazareva, O.; Sparks, D. L.; Landis, R.; Ptacek, C. J.; Hicks, S.; Montgomery, D.

    2013-12-01

    Mercury (Hg) was used between 1929 and 1950 by the DuPont plant in the production of rayon acetate fiber in Waynesboro, Virginia and released into the South River. The contamination of Hg was discovered in the 1970s and remained elevated in water, soil, sediments, and biota. The primary goal of this study is to investigate the processes that govern biogeochemical transformation and mobilization of Hg in floodplain soils at South River Mile 3.5, characterize geochemical gradients in soils and how they change over time, and to enable targeted sampling at Hg loading hot spots. The biogeochemical data will play a supporting role and be used to further develop our understanding of the processes controlling the leaching of Hg and our conceptual model. Our over-arching hypothesis is to test if leaching of bank soils is a significant source of dissolved or colloidal inorganic Hg. This effort requires an interdisciplinary geochemical approach and sensor technology to understand the interactions between floodplain soil, groundwater, and river. Our investigation will include 10 months' worth data from a number of state-of-the-art in-situ monitoring sensors, such as custom-designed redox probes, soil moisture, temperature, pressure, and conductivity installed at the site. Our preliminary results showed that the concentration of total Hg in soils was up to 900 mg/kg (wet weight).There is a significant redox gradient across the floodplain soil profile. Within the top 40 -70 cm, major changes in redox conditions from oxidizing (Eh ≈+600 mV) to very reducing (Eh ≈-300 mV) corresponded to heavy rainfall and overbank flooding events. High variations in stream stage may govern the surface water - groundwater exchange facilitating the downward or upward movement of the capillary fringe and saturated zone through the soil horizons, affecting soil redox potential, stability of Hg-bearing minerals and leaching of inorganic Hg into dissolved and colloidal phases. These phases may be

  4. Drying of Floodplain Forests Associated with Water-Level Decline in the Apalachicola River, Florida - Interim Results, 2006

    USGS Publications Warehouse

    Darst, Melanie R.; Light, Helen M.

    2007-01-01

    Floodplain forests of the Apalachicola River, Florida, are drier in composition today (2006) than they were before 1954, and drying is expected to continue for at least the next 50 years. Drier forest composition is probably caused by water-level declines that occurred as a result of physical changes in the main channel after 1954 and decreased flows in spring and summer months since the 1970s. Forest plots sampled from 2004 to 2006 were compared to forests sampled in the late 1970s (1976-79) using a Floodplain Index (FI) based on species dominance weighted by the Floodplain Species Category, a value that represents the tolerance of tree species to inundation and saturation in the floodplain and consequently, the typical historic floodplain habitat for that species. Two types of analyses were used to determine forest changes over time: replicate plot analysis comparing present (2004-06) canopy composition to late 1970s canopy composition at the same locations, and analyses comparing the composition of size classes of trees on plots in late 1970s and in present forests. An example of a size class analysis would be a comparison of the composition of the entire canopy (all trees greater than 7.5 cm (centimeter) diameter at breast height (dbh)) to the composition of the large canopy tree size class (greater than or equal to 25 cm dbh) at one location. The entire canopy, which has a mixture of both young and old trees, is probably indicative of more recent hydrologic conditions than the large canopy, which is assumed to have fewer young trees. Change in forest composition from the pre-1954 period to approximately 2050 was estimated by combining results from three analyses. The composition of pre-1954 forests was represented by the large canopy size class sampled in the late 1970s. The average FI for canopy trees was 3.0 percent drier than the average FI for the large canopy tree size class, indicating that the late 1970s forests were 3.0 percent drier than pre-1954

  5. Relations among floodplain water levels, instream dissolved-oxygen conditions, and streamflow in the lower Roanoke River, North Carolina, 1997-2001

    USGS Publications Warehouse

    Bales, Jerad D.; Walters, Douglas A.

    2004-01-01

    The lower Roanoke River corridor in North Carolina contains a floodplain of national significance. Data from a network of 1 streamflow-measurement site, 13 river-stage sites, 13 floodplain water-level sites located along 4 transects, and 5 in situ water-quality monitoring sites were used to characterize temporal and spatial variations of floodplain and river water levels during 1997-2000 and to describe dissolved-oxygen conditions in the lower Roanoke River for the period 1998-2001. Major differences in the relation of floodplain inundation to flow occurred both among sites at a given transect and among transects. Several floodplain sites were inundated for the full range of flow conditions measured during the study. These included one site on the Big Swash transect (at about river kilometer 119); one site on the Broadneck Swamp transect (river kilometer 97), which was inundated 91 percent of the time during the study; one site on the Devils Gut transect (river kilometer 44), which was inundated throughout the study; and three sites on the Cow Swamp transect (near river kilometer 10). The relation of floodplain inundation depth to Roanoke River flow was highly variable among sites. There was no relation between flow and inundation depth at one of the Big Swash sites or at any of the four Cow Swamp sites. At two of the Big Swash transect sites, there was some relation between inundation depth and 10-day mean flow for flows greater than 700 cubic meters per second. A relatively strong relation between inundation depth and 10-day mean flow occurred at two of the Broadneck Swamp sites and, to a lesser degree, at two of the Devils Gut transect sites. There was much greater interannual variability in floodplain water levels, as represented by the difference between the maximum and minimum daily water level for a given calendar date during January-May and September-October than during the summer and late fall months. If data from this study are representative of long

  6. Diversity and genetic distance in populations of Steindachnerina in the upper Paraná river floodplain of Brazil.

    PubMed

    Oliveira, A V; Prioli, A J; Prioli, S M A P; Pavanelli, C S; Júlio, H F; Panarari, R S

    2002-08-01

    Whereas four species of the genus Steindachnerina occur in the Paraná river basin, S. insculpta was the only endemic species of the region under analysis, which is the third lower section of the upper Paraná river. Among other factors, this species has been characterised by the absence of spots in the basal region of the dorsal fin. However, various specimens with this characteristic appeared in the region after the construction of the Itaipu Hydroelectric Plant in 1982. An analysis of the genetic variability of Steindachnerina populations with or without spots is provided. Specimens were collected in different sites of the floodplain of the upper Paraná river and samples were compared by random amplified polymorphic DNA (RAPD) technique and morphological analyses. Ninety-eight amplified loci with nine random primers were analysed in 19 specimens of each phenotype. Data for genetic distance showed great divergences between the two phenotypes and indicate two different species. Spotted specimens may be identified as S. brevipinna, found in the region downstream Sete Quedas Falls. The species must have overcome the geographical barrier during the building of the Itaipu hydroelectric dam that submerged the waterfalls and which became an obstacle between the upper and middle Paraná river some 150 km downstream. Since phenotypes do not share dominant alleles, absence of gene flow has been suggested. PMID:12440565

  7. Diversity and genetic distance in populations of Steindachnerina in the upper Paraná river floodplain of Brazil.

    PubMed

    Oliveira, A V; Prioli, A J; Prioli, S M A P; Pavanelli, C S; Júlio, H F; Panarari, R S

    2002-08-01

    Whereas four species of the genus Steindachnerina occur in the Paraná river basin, S. insculpta was the only endemic species of the region under analysis, which is the third lower section of the upper Paraná river. Among other factors, this species has been characterised by the absence of spots in the basal region of the dorsal fin. However, various specimens with this characteristic appeared in the region after the construction of the Itaipu Hydroelectric Plant in 1982. An analysis of the genetic variability of Steindachnerina populations with or without spots is provided. Specimens were collected in different sites of the floodplain of the upper Paraná river and samples were compared by random amplified polymorphic DNA (RAPD) technique and morphological analyses. Ninety-eight amplified loci with nine random primers were analysed in 19 specimens of each phenotype. Data for genetic distance showed great divergences between the two phenotypes and indicate two different species. Spotted specimens may be identified as S. brevipinna, found in the region downstream Sete Quedas Falls. The species must have overcome the geographical barrier during the building of the Itaipu hydroelectric dam that submerged the waterfalls and which became an obstacle between the upper and middle Paraná river some 150 km downstream. Since phenotypes do not share dominant alleles, absence of gene flow has been suggested.

  8. Flood-plain and channel aggradation of selected bridge sites in the Iowa and Skunk River basins, Iowa

    USGS Publications Warehouse

    Eash, D.A.

    1996-01-01

    Flood-plain and channel-aggradation rates were estimated at 10 bridge sites on the Iowa River upstream of Coralville Lake and at two bridge sites in the central part of the Skunk River Basin. Four measurement methods were used to quantify aggradation rates: (1) a dendrogeomorphic method that used tree-age data and sediment-deposition depths, (2) a bridge-opening cross-section method that compared historic and recent cross sections of bridge openings, (3) a stage-discharge rating-curve method that compared historic and recent stages for the 5-year flood discharge and the average discharge, and (4) nine sediment pads that were installed on the Iowa River flood plain at three bridge sites in the vicinity of Marshalltown. The sediment pads were installed prior to overbank flooding in 1993. Sediments deposited on the pads as a result of the 1993 flood ranged in depth from 0.004 to 2.95 feet. Measurement periods used to estimate average aggradation rates ranged from 1 to 98 years and varied among methods and sites. The highest aggradation rates calculated for the Iowa River Basin using the dendrogeomorphic and rating- curve measurement methods were for the State Highway 14 crossing at Marshalltown, where these highest rates were 0.045 and 0.124 feet per year, respectively. The highest aggradation rates calculated for the Skunk River Basin were for the U.S. Highway 63 crossing of the South Skunk River near Oskaloosa, where these highest rates were 0.051 and 0.298 feet per year, respectively.

  9. 75 FR 5279 - Sucker Creek Channel and Floodplain Restoration Project (Phase II), Rogue River-Siskiyou National...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-02

    ...; ] DEPARTMENT OF AGRICULTURE Forest Service Sucker Creek Channel and Floodplain Restoration Project (Phase II..., Oregon. Purpose and Need for Action The purpose of the Sucker Creek Channel and Floodplain Restoration... show that the stream channel was more sinuous and contained a larger floodplain, characteristic of...

  10. Bioaccessibility of arsenic in mining-impacted circumneutral river floodplain soils.

    PubMed

    Mikutta, Christian; Mandaliev, Petar N; Mahler, Nina; Kotsev, Tsvetan; Kretzschmar, Ruben

    2014-11-18

    Floodplain soils are frequently contaminated with metal(loid)s due to present or historic mining, but data on the bioaccessibility (BA) of contaminants in these periodically flooded soils are scarce. Therefore, we studied the speciation of As and Fe in eight As-contaminated circumneutral floodplain soils (≤ 21600 mg As/kg) and their size fractions using X-ray absorption spectroscopy (XAS) and examined the BA of As in the solids by in-vitro gastrointestinal (IVG) extractions. Arsenopyrite and As(V)-adsorbed ferrihydrite were identified by XAS as the predominant As species. The latter was the major source for bioaccessible As, which accounted for 5-35% of the total As. The amount of bioaccessible As increased with decreasing particle size and was controlled by the slow dissolution kinetics of ferrihydrite in the gastric environment (pH 1.8). The relative BA of As (% of total) decreased with decreasing particle size only in a highly As-contaminated soil--which supported by Fe XAS--suggests the formation of As-rich hydrous ferric oxides in the gastric extracts. Multiple linear regression analyses identified Al, total As, C(org), and P as main predictors for the absolute BA of As (adjusted R(2) ≤ 0.977). Health risk assessments for residential adults showed that (i) nearly half of the bulk soils may cause adverse health effects and (ii) particles <5 μm pose the highest absolute health threat upon incidental soil ingestion. Owing to their low abundance, however, health risks were primarily associated with particles in the 5-50 and 100-200 μm size ranges. These particles are easily mobilized from riverbanks during flooding events and dispersed within the floodplain or transported downstream. PMID:25358072

  11. Bioaccessibility of arsenic in mining-impacted circumneutral river floodplain soils.

    PubMed

    Mikutta, Christian; Mandaliev, Petar N; Mahler, Nina; Kotsev, Tsvetan; Kretzschmar, Ruben

    2014-11-18

    Floodplain soils are frequently contaminated with metal(loid)s due to present or historic mining, but data on the bioaccessibility (BA) of contaminants in these periodically flooded soils are scarce. Therefore, we studied the speciation of As and Fe in eight As-contaminated circumneutral floodplain soils (≤ 21600 mg As/kg) and their size fractions using X-ray absorption spectroscopy (XAS) and examined the BA of As in the solids by in-vitro gastrointestinal (IVG) extractions. Arsenopyrite and As(V)-adsorbed ferrihydrite were identified by XAS as the predominant As species. The latter was the major source for bioaccessible As, which accounted for 5-35% of the total As. The amount of bioaccessible As increased with decreasing particle size and was controlled by the slow dissolution kinetics of ferrihydrite in the gastric environment (pH 1.8). The relative BA of As (% of total) decreased with decreasing particle size only in a highly As-contaminated soil--which supported by Fe XAS--suggests the formation of As-rich hydrous ferric oxides in the gastric extracts. Multiple linear regression analyses identified Al, total As, C(org), and P as main predictors for the absolute BA of As (adjusted R(2) ≤ 0.977). Health risk assessments for residential adults showed that (i) nearly half of the bulk soils may cause adverse health effects and (ii) particles <5 μm pose the highest absolute health threat upon incidental soil ingestion. Owing to their low abundance, however, health risks were primarily associated with particles in the 5-50 and 100-200 μm size ranges. These particles are easily mobilized from riverbanks during flooding events and dispersed within the floodplain or transported downstream.

  12. Floodplain forest loss and changes in forest community composition and structure in the upper Mississippi River: a wildlife habitat at risk

    USGS Publications Warehouse

    Knutson, M.G.; Klaas, E.E.

    1998-01-01

    Large floodplain forests represent a threatened and endangered type of ecosystem in the United States. Estimates of cumulative losses of floodplain forest range from 57% to 95% at different locations within the continental United Stales. Floodplain forests of the Upper Mississippi River (UMR) have significantly declined in extent due to agriculture, lock and dam construction, and urban development since European settlement. We collected data on shrubs, herbs, and trees from 56 floodplain forest plots in 1992 and compared our results with a previous analysis of historical tree data from the same area recorded by the General Land Office Survey in the 1840s. Acer saccharinum strongly dominates among mature trees and its relative dominance has increased over time. Salix spp. And Betula nigra have declined in relative dominance. Tree sizes are similar to those of presettlement forests, but present forests have fewer trees. The lack of early successional tree species and a trend toward an increasing monoculture of A. Saccharinum in the mature stages indicate problems with regeneration. Because floodplain forests represent a rare habitat type, losses and changes in habitat quality could pose serious problems for wildlife that depend upon these habitats, especially birds.

  13. Morphodynamics of Floodplain Chute Channels

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Floodplain chute channel formation is a key process that can enable rivers to transition from single-thread to multi-thread planform geometries. Floodplain chute channels are usually incisional channels connecting topographic lows across point bars and in the floodplain. Surprisingly, it is still not clear what conditions promote chute channel formation and what governs their morphodynamic behavior. Towards this end we have initiated an empirical and theoretical study of floodplain chute channels in Indiana, USA. Using elevation models and satellite imagery we mapped 3064 km2 of floodplain in Indiana, and find that 37.3% of mapped floodplains in Indiana have extensive chute channel networks. These chute channel networks consist of two types of channel segments: meander cutoffs of the main channel and chute channels linking the cutoffs together. To understand how these chute channels link meander cutoffs together and eventually create floodplain channel networks we use Delft3D to explore floodplain morphodynamics. Our first modeling experiment starts from a generic floodplain prepopulated with meander cutoffs to test under what conditions chute channels form.We find that chute channel formation is optimized at an intermediate flood discharge. If the flood discharge is too large the meander cutoffs erosively diffuse, whereas if the floodwave is too small the cutoffs fill with sediment. A moderately sized floodwave reworks the sediment surrounding the topographic lows, enhancing the development of floodplain chute channels. Our second modeling experiments explore how floodplain chute channels evolve on the West Fork of the White River, Indiana, USA. We find that the floodplain chute channels are capable of conveying the entire 10 yr floodwave (Q=1330m3/s) leaving the inter-channel areas dry. Moreover, the chute channels can incise into the floodplain while the margins of channels are aggrading, creating levees. Our results suggest that under the right conditions

  14. Public support for river restoration. A mixed-method study into local residents' support for and framing of river management and ecological restoration in the Dutch floodplains.

    PubMed

    Buijs, Arjen E

    2009-06-01

    In many European countries, accommodating water has become the dominant paradigm in river management. In the Netherlands, extensive river restoration projects are being implemented, many of which draw serious opposition from the public. To investigate the causes of such opposition, a comprehensive study of public attitudes towards river restoration was conducted in three floodplains, both before and after river restoration. The study combined quantitative questionnaires (N=562) with open interviews (N=29). This paper describes how local residents perceive the effects of river restoration on landscape quality and how residents and protest groups use landscape quality in combination with other arguments to strategically frame river management policies. Results show that measurement of the perceived outcomes of nature restoration needs to be complemented by a more dynamic type of research, focusing on the social processes of the framing of restoration plans. Theoretically, the paper aims to contribute to the development of a rigorous research strategy to study framing processes in environmental management, using a mixed-methods approach. In general, local residents are supportive of river restoration projects. Although restoration may diminish feelings of attachment to an area, for most people this negative effect is compensated by the positive effects on scenic beauty and perceived protection from flooding. However, these positive effects may become contested because of the active framing of river restoration by protest groups. Residents use three distinct frames to give meaning to river restoration projects: (i) an attachment frame, focusing on cultural heritage and place attachment (ii) an attractive nature frame, focusing on nature as attractive living space and the intrinsic value of nature (iii) a rurality frame, focusing on rural values, agriculture and cultural heritage. Resistance to river restoration plans stems from the attachment and rurality frames

  15. Public support for river restoration. A mixed-method study into local residents' support for and framing of river management and ecological restoration in the Dutch floodplains.

    PubMed

    Buijs, Arjen E

    2009-06-01

    In many European countries, accommodating water has become the dominant paradigm in river management. In the Netherlands, extensive river restoration projects are being implemented, many of which draw serious opposition from the public. To investigate the causes of such opposition, a comprehensive study of public attitudes towards river restoration was conducted in three floodplains, both before and after river restoration. The study combined quantitative questionnaires (N=562) with open interviews (N=29). This paper describes how local residents perceive the effects of river restoration on landscape quality and how residents and protest groups use landscape quality in combination with other arguments to strategically frame river management policies. Results show that measurement of the perceived outcomes of nature restoration needs to be complemented by a more dynamic type of research, focusing on the social processes of the framing of restoration plans. Theoretically, the paper aims to contribute to the development of a rigorous research strategy to study framing processes in environmental management, using a mixed-methods approach. In general, local residents are supportive of river restoration projects. Although restoration may diminish feelings of attachment to an area, for most people this negative effect is compensated by the positive effects on scenic beauty and perceived protection from flooding. However, these positive effects may become contested because of the active framing of river restoration by protest groups. Residents use three distinct frames to give meaning to river restoration projects: (i) an attachment frame, focusing on cultural heritage and place attachment (ii) an attractive nature frame, focusing on nature as attractive living space and the intrinsic value of nature (iii) a rurality frame, focusing on rural values, agriculture and cultural heritage. Resistance to river restoration plans stems from the attachment and rurality frames

  16. On the investigation of the performances of a DEM-based hydrogeomorphic floodplain identification method in a large urbanized river basin: the Tiber river case study in Italy

    NASA Astrophysics Data System (ADS)

    Nardi, Fernando; Biscarini, Chiara; Di Francesco, Silvia; Manciola, Piergiorgio

    2013-04-01

    Floodplains are critical landscape features for their importance in both ecohydrological and socio-economic terms. River valleys are, in fact, the domain where the interdependence of the complex human-environmental interface is more significant. Riparian zones, along perennial channels, where the frequency of saturation is high and most flooding occurs, are also the areas where urban areas and infrastructures (e.g. highways, bridges, railways, etc) are more present. This is mainly due to geomorphologic conditions since those areas are predominantly flat and easier to develop. One of the more challenging issues under changing climatic, environmental and human drivers for implementing efficient current and future urban plans is to accurately and timely identify, map and characterize the potential flooding scenarios of floodplains. This is currently achieved by implementing detailed topographic, hydrologic and hydraulic studies for flood modeling and mapping for different frequencies (i.e. return time), but those activities are rarely implemented at the large (river basin) scale for their economic cost and time of implementation. In addition to that, flood map updating is not as frequent as needed for following the rapid changing land use conditions. As a result, it is very often the case that urban plans are based on heterogeneous and discontinuous flood map information. Nevertheless, several recent researches demonstrated the potential for the use of high resolution digital elevation models (DEMs) to define the floodplain feature by means of automated hydrogeomorphic methods. This means identifying the flood prone area by filtering potentially inundated cells by implementing proper morphological and hydrological analyses. In this work we implemented the flooplain identification model proposed by Nardi et al. (WRR, 2006) which automatically extract the river network and estimate flood water levels according to a predefined scaling Leopold law. Inundated areas are

  17. A conceptual model for groundwater - surface water interactions in the Darling River Floodplain, N.S.W., Australia

    NASA Astrophysics Data System (ADS)

    Brodie, R. S.; Lawrie, K.; Somerville, P.; Hostetler, S.; Magee, J.; Tan, K. P.; Clarke, J.

    2013-12-01

    Multiple lines of evidence were used to develop a conceptual model for interaction between the Darling River and associated floodplain aquifers in western New South Wales, Australia. Hydrostratigraphy and groundwater salinities were mapped using airborne electromagnetics (AEM), validated by sonic-core drilling. The AEM was highly effective in mapping groundwater freshening due to river leakage in discrete zones along the river corridor. These fresh resources occurred in both the unconfined Quaternary aquifers and the underlying, largely semi-confined Pliocene aquifers. The AEM was also fundamental to mapping the Blanchetown Clay aquitard which separates these two aquifer systems. Major-ion chemistry highlighted a mixing signature between river waters and groundwaters in both the Quaternary and Pliocene aquifers. Stable isotope data indicates that recharge to the key Pliocene aquifers is episodic and linked to high-flow flood events rather than river leakage being continuous. This was also evident when groundwater chemistry was compared with river chemistry under different flow conditions. Mapping of borehole levels showed groundwater mounding near the river, emphasising the regional significance of losing river conditions for both aquifer systems. Critically, rapid and significant groundwater level responses were measured during large flood events. In the Pliocene aquifers, continuation of rising trends after the flood peak receded confirms that this is an actual recharge response rather than hydraulic loading. The flow dependency of river leakage can be explained by the presence of mud veneers and mineral precipitates along the Darling River channel bank when river flows are low. During low flow conditions these act as impediments to river leakage. During floods, high flow velocities scour these deposits, revealing lateral-accretion surfaces in the shallow scroll plain sediments. This scouring allows lateral bank recharge to the shallow aquifer. During flood

  18. Interannual variability of phytoplankton in the main rivers of the Upper Paraná River floodplain, Brazil: influence of upstream reservoirs.

    PubMed

    Rodrigues, L C; Train, S; Bovo-Scomparin, V M; Jati, S; Borsalli, C C J; Marengoni, E

    2009-06-01

    The interannual variation of phytoplankton communities in the three main rivers of the Upper Paraná River floodplain is evaluated in relation to changes in the hydrosedimentological regime. These changes are a result of climatic variability and the formation of Porto Primavera Reservoir, located at the upper Paraná River. Phytoplankton species richness and density were investigated in rivers during a prior period (1993-1994) and eight years after reservoir impoundment (2000-2007). Multiple analyses were conducted to test the differences between these time periods in order to find predictor variables for phytoplankton attributes. A total of 454 phytoplanktonic taxa were found. The regression analysis revealed significant differences between periods. In the years following construction of the Porto Primavera dam, species richness was lower in the Paraná River and density was higher in the three rivers. In general, the algal density decreased from 2005 to 2007. Diatoms and cyanobacteria contributed significantly to the total density during the period from March 1993 to February 1994. The years 2000-2007 presented the lowest diatom contribution to species richness and the highest cyanobacteria contribution. From 2000 on, cryptomonads and cyanobacteria dominated. The interannual variability of phytoplankton was probably influenced by changes in hydrosedimentological regime due to climatic variations (La Niña and El Niño-Southern Oscillation events--ENSO) and the operational procedures associated with an upstream reservoirs. Studies on climatic variability and its effects on hydrosedimentological regimes of the Paraná, Baía and Ivinhema rivers and the biota therein are necessary to obtain subsidies for management, including decisions related to the operation of dams upstream and downstream of the study area, with the purpose of minimizing risks to the Environmental Protection Area.

  19. Soil controls on land-atmosphere methane fluxes from an arctic floodplain of the Lena River Delta, Siberia

    NASA Astrophysics Data System (ADS)

    Runkle, Benjamin; Sabrekov, Alexander; Glagolev, Mikail; Kutzbach, Lars

    2014-05-01

    Accurately quantifying methane emissions from permafrost tundra landscapes into the atmosphere is a major concern of the global climate modeling community. A better, data-driven understanding of the drivers of soil-atmosphere CH4 fluxes could help constrain the global methane balance, offer predictions in response to global climate change, and advance understanding of these regions' soil biogeochemistry and landscape ecology. Previous research at our Lena River Delta research site (72° N, 126° E) has found relatively low methane emissions (~18-30 mg m2 d1) in the polygonal tundra of the delta's Holocene river terrace (Sachs et al., 2008; Wille et al., 2008). In fall 2013 we compare methane emissions from this landscape type to the adjacent active river floodplain, a sandy, Equisetum - Salix -Alopecurus alpinus community ecosystem. This landscape has backswamp regions with higher organic matter accumulation though is generally dominated by soils with high sand contents, low organic matter content, and lower water tables than the Holocene terrace (Boike et al., 2013). The wet parts of a similar landscape unit in the Indigirka lowlands (71° N, 147° E) have been demonstrated to have greater methane emissions which were in part attributed to the annual deposition of nutrients via flooding, increased primary productivity and associated root exudates, and higher soil temperatures. The results presented in this study compare methane fluxes derived from the closed chamber technique from the two landscape units. In addition to descriptions of the inundation height and vegetation cover, we examine soil chemical and physical characteristics to test how these factors help control CH4 fluxes. We find, for example, relatively high concentrations of dissolved organic carbon at sites with relatively high CH4 production. As the modern floodplain landscape type covers 40% of the soil-covered area of the Lena River Delta and is analogous to similar regions across the Arctic

  20. Abundance and patterns of transparent exopolymer particles (TEP) in Arctic floodplain lakes of the Mackenzie River Delta

    NASA Astrophysics Data System (ADS)

    Chateauvert, C. Adam; Lesack, Lance F. W.; Bothwell, Max L.

    2012-12-01

    The Mackenzie River Delta is a lake-rich arctic floodplain that receives high inputs of dissolved organic matter (DOM) and suspended particulates from allochthonous and autochthonous sources, and may transfer carbon from dissolved to particulate phase via in situ formation of transparent exopolymer particles (TEP). TEP provides food for grazers, surfaces for bacteria, and increased potential for aggregation and sedimentation of organic matter. During open water 2006, we tracked TEP abundances in three Delta lakes representing gradients that include declining river-to-lake connection times, increasing levels of dissolved organic carbon (DOC), and declining chromophoric-DOM (CDOM). Unexpectedly, TEP abundances were highest immediately after the flood, when autochthonous autotrophic production was at a seasonal low and CDOM a seasonal high. Moreover, the lake with the strongest riverine influence and lowest levels of autochthonous autotrophic production had the highest mean TEP-carbon (TEP-C) concentrations among the lakes. The mean proportion of particulate organic carbon (POC) represented by TEP-C increased with increasing river connection time, and appears to represent a substantial proportion of POC in Mackenzie Delta Lakes. Unexpectedly, the TEP gradient was most strongly related to CDOM (river water source) rather than overall DOC. Variations in CDOM accounted for 53% of TEP-C variation among the lakes, indicating allochthonous matter was the most important source of TEP. DOC release from in situ macrophytes during periods of high photosynthesis may contribute to TEP formation in the lake with lowest riverine influence, but pH levels >9.5 driven by the high photosynthetic rates complicate the interpretation of results from this lake.

  1. Validity and sensitivity of a model for assessment of impacts of river floodplain reconstruction on protected and endangered species

    SciTech Connect

    Nooij, R.J.W. de . E-mail: R.deNooij@science.ru.nl; Lotterman, K.M.; Sande, P.H.J. van de; Pelsma, T.; Leuven, R.S.E.W.; Lenders, H.J.R.

    2006-11-15

    Environmental Impact Assessment (EIA) must account for legally protected and endangered species. Uncertainties relating to the validity and sensitivity of EIA arise from predictions and valuation of effects on these species. This paper presents a validity and sensitivity analysis of a model (BIO-SAFE) for assessment of impacts of land use changes and physical reconstruction measures on legally protected and endangered river species. The assessment is based on links between species (higher plants, birds, mammals, reptiles and amphibians, butterflies and dragon- and damselflies) and ecotopes (landscape ecological units, e.g., river dune, soft wood alluvial forests), and on value assignment to protected and endangered species using different valuation criteria (i.e., EU Habitats and Birds directive, Conventions of Bern and Bonn and Red Lists). The validity of BIO-SAFE has been tested by comparing predicted effects of landscape changes on the diversity of protected and endangered species with observed changes in biodiversity in five reconstructed floodplains. The sensitivity of BIO-SAFE to value assignment has been analysed using data of a Strategic Environmental Assessment concerning the Spatial Planning Key Decision for reconstruction of the Dutch floodplains of the river Rhine, aimed at flood defence and ecological rehabilitation. The weights given to the valuation criteria for protected and endangered species were varied and the effects on ranking of alternatives were quantified. A statistically significant correlation (p < 0.01) between predicted and observed values for protected and endangered species was found. The sensitivity of the model to value assignment proved to be low. Comparison of five realistic valuation options showed that different rankings of scenarios predominantly occur when valuation criteria are left out of the assessment. Based on these results we conclude that linking species to ecotopes can be used for adequate impact assessments

  2. Insect emergence in relation to floods in wet meadows and swamps in the River Dalälven floodplain.

    PubMed

    Vinnersten, T Z Persson; Östman, Ö; Schäfer, M L; Lundström, J O

    2014-08-01

    Annual variation in flood frequency and hydroperiod during the vegetation season has ecological impacts on the floodplain biota. Although many insect groups may have a lower emergence during a flood event, it is poorly known how annual emergence of insects in temporary wetlands is related to the variation in hydrology. Between May and September, we studied the weekly emergence of 18 insect taxa over six consecutive years, 2002-2007, in six temporary flooded wetlands (four wet meadows and two forest swamps) in the River Dalälven floodplains, Central Sweden. We used emergence traps to collect emerging insects from terrestrial and aquatic parts of wet meadows and swamp forests. In all wetlands, the insect fauna was numerically dominated by the orders Diptera, Hymenoptera, Coleoptera and Homoptera. On a weekly basis, 9 out of the 18 insect taxa had lower emergence in weeks with flood than in weeks with no flood, whereas no taxon had a higher emergence in weeks with flood. Over the seasons, we related insect emergence to seasonal flood frequency and length of hydroperiod. The emergence of most studied taxa decreased with increasing hydroperiod, which suggests that emergence after floods do not compensate for the reduced emergence during floods. Only Culicidae and the aquatic Chironomidae sub-families Tanypodinae and Chironominae showed an increase in emergence with increasing hydroperiod, whereas Staphylinidae peaked at intermediate hydroperiod. We conclude that a hydroperiod covering up to 40% of the vegetation season has a significant negative effect on the emergence of most taxa and that only a few taxa occurring in the temporary wetlands are actually favoured by a flood regime with recurrent and unpredictable floods. PMID:24521711

  3. Insect emergence in relation to floods in wet meadows and swamps in the River Dalälven floodplain.

    PubMed

    Vinnersten, T Z Persson; Östman, Ö; Schäfer, M L; Lundström, J O

    2014-08-01

    Annual variation in flood frequency and hydroperiod during the vegetation season has ecological impacts on the floodplain biota. Although many insect groups may have a lower emergence during a flood event, it is poorly known how annual emergence of insects in temporary wetlands is related to the variation in hydrology. Between May and September, we studied the weekly emergence of 18 insect taxa over six consecutive years, 2002-2007, in six temporary flooded wetlands (four wet meadows and two forest swamps) in the River Dalälven floodplains, Central Sweden. We used emergence traps to collect emerging insects from terrestrial and aquatic parts of wet meadows and swamp forests. In all wetlands, the insect fauna was numerically dominated by the orders Diptera, Hymenoptera, Coleoptera and Homoptera. On a weekly basis, 9 out of the 18 insect taxa had lower emergence in weeks with flood than in weeks with no flood, whereas no taxon had a higher emergence in weeks with flood. Over the seasons, we related insect emergence to seasonal flood frequency and length of hydroperiod. The emergence of most studied taxa decreased with increasing hydroperiod, which suggests that emergence after floods do not compensate for the reduced emergence during floods. Only Culicidae and the aquatic Chironomidae sub-families Tanypodinae and Chironominae showed an increase in emergence with increasing hydroperiod, whereas Staphylinidae peaked at intermediate hydroperiod. We conclude that a hydroperiod covering up to 40% of the vegetation season has a significant negative effect on the emergence of most taxa and that only a few taxa occurring in the temporary wetlands are actually favoured by a flood regime with recurrent and unpredictable floods.

  4. Lead exposure in passerines inhabiting lead-contaminated floodplains in the Coeur d'Alene River Basin, Idaho, USA

    SciTech Connect

    Johnson, G.D.; Kern, J.W.; Strickland, M.D.; McDonald, L.L. ); Audet, D.J.; LeCaptain, L.J. ); Hoffman, D.J. )

    1999-06-01

    Blood collected from song sparrows (Melospiza melodia) and American robins (Turdus migratorius) captured with mist nets in a lead-contaminated (assessment) area and nearby uncontaminated (reference) areas within the Coeur d'Alene Basin in northern Idaho was analyzed for [delta]-aminolevulinic acid dehydratase activity (ALAD) and hematocrit levels, and livers were analyzed for lead. Mean ALAD inhibition in the assessment area was 51% in song sparrows and 75% in American robins. The proportion of the sampled population with ALAD inhibition > 50% was calculated to be 43% for song sparrows and 83% for American robins. Assessment area hematocrit values for song sparrows and American robins were lower than in reference areas; however, differences were not statistically significant. Significantly higher levels of lead (wet weight) were found in livers from song sparrows captured on the assessment area ([bar x] = 1.93 ppm) than on reference areas. Study results indicate that 43% of the song sparrows and 83% of the American robins inhabiting the floodplain along the Coeur d'Alene River in the assessment area are being exposed to lead at levels sufficient to inhibit ALAD by > 50%. Variability in lead exposure indicators was attributed to high variability in environmental lead concentrations in the Coeur d'Alene River Basin.

  5. Great horned owl (Bubo virginianus) dietary exposure to PCDD/DF in the Tittabawassee River floodplain in Midland, Michigan, USA.

    PubMed

    Coefield, Sarah J; Zwiernik, Matthew J; Fredricks, Timothy B; Seston, Rita M; Nadeau, Michael W; Tazelaar, Dustin L; Moore, Jeremy N; Kay, Denise P; Roark, Shaun A; Giesy, John P

    2010-10-01

    Soils and sediments in the floodplain of the Tittabawassee River downstream of Midland, Michigan, USA contain elevated concentrations of polychlorinated dibenzofurans (PCDF) and polychlorinated dibenzo-p-dioxins (PCDD). As a long-lived, resident top predator, the great horned owl (Bubo virginianus; GHO) has the potential to be exposed to bioaccumulative compounds such as PCDD/DF. Site-specific components of the GHO diet were collected along 115 km of the Tittabawassee, Pine, Chippewa, and Saginaw Rivers during 2005 and 2006. The site-specific GHO biomass-based diet was dominated by cottontail rabbits (Sylvilagus floridanus) and muskrats (Ondatra zibethicus). Incidental soil ingestion and cottontail rabbits were the primary contributors of PCDD/DF to the GHO diet. The great horned owl daily dietary exposure estimates were greater in the study area (SA) (3.3 to 5.0 ng 2,3,7,8-TCDD equivalents (TEQ(WHO-avian))/kg body wt/d) than the reference area (RA) (0.07 ng TEQ(WHO-Avian)/kg body wt/d). Hazard quotients (HQs) based on central tendency estimates of the average daily dose and no-observable-adverse effect level (NOAEL) for the screech owl and uncertainty factors were <1.0 for both the RA and the SA. Hazard quotients based on upper end estimates of the average daily dose and NOAEL were <1.0 in the RA and up to 3.4 in the SA. PMID:20872700

  6. Spatial relations between floodplain environments and land use - land cover of a large lowland tropical river valley: Pánuco basin, México.

    PubMed

    Hudson, Paul F; Colditz, René R; Aguilar-Robledo, Miguel

    2006-09-01

    Large lowland river valleys include a variety of floodplain environments that represent opportunities and constraints for human activities. This study integrates extensive field observations and geomorphic data with analysis of satellite remote sensing data to examine spatial relations between land use/land cover (LULC) and floodplain environments in the lower Pánuco basin of eastern Mexico. The floodplain of the lower Pánuco basin was delineated by combining a digital elevation model with a satellite image of a large flood event. The LULC was classified by combining a hybrid classification strategy with image stratification, applied to 15-m-resolution ASTER data. A geomorphic classification of floodplain environments was performed using a dry-stage image (ASTER data) and a 1993 Landsat image acquired during a large flood event. Accuracy assessment was based on aerial photographs (1:38,000), global positioning satellite ground-truthing, and a Landsat 7ETM(+) image from 2000, which resulted in an overall accuracy of 82.9% and a KHAT of 79.8% for the LULC classification. The geomorphic classification yielded 83.5% overall accuracy, whereas the KHAT was 81.5%. LULC analysis was performed for the entire floodplain and individually within four valley segments. The analysis indicates that the study area is primarily utilized for grazing and farming. Agriculture is primarily associated with coarse-grained (sandy/silty) natural levee and point bar units close to the river channel, whereas cattle grazing occurs in distal and lower-lying reaches dominated by cohesive fine-grained (clayey) deposits, such as backswamps. In the Pánuco valley, wetlands and lakes occur within backswamp environments, whereas in the Moctezuma segments, wetlands and lakes are associated with relict channels. This study reveals considerable variation in LULC related to spatial differences in floodplain environments and illustrates the importance of considering older anthropogenic influences on the

  7. Spatial scaling of core and dominant forest cover in the Upper Mississippi and Illinois River floodplains, USA

    USGS Publications Warehouse

    De Jager, Nathan R.; Rohweder, Jason J.

    2011-01-01

    Different organisms respond to spatial structure in different terms and across different spatial scales. As a consequence, efforts to reverse habitat loss and fragmentation through strategic habitat restoration ought to account for the different habitat density and scale requirements of various taxonomic groups. Here, we estimated the local density of floodplain forest surrounding each of ~20 million 10-m forested pixels of the Upper Mississippi and Illinois River floodplains by using moving windows of multiple sizes (1–100 ha). We further identified forest pixels that met two local density thresholds: 'core' forest pixels were nested in a 100% (unfragmented) forested window and 'dominant' forest pixels were those nested in a >60% forested window. Finally, we fit two scaling functions to declines in the proportion of forest cover meeting these criteria with increasing window length for 107 management-relevant focal areas: a power function (i.e. self-similar, fractal-like scaling) and an exponential decay function (fractal dimension depends on scale). The exponential decay function consistently explained more variation in changes to the proportion of forest meeting both the 'core' and 'dominant' criteria with increasing window length than did the power function, suggesting that elevation, soil type, hydrology, and human land use constrain these forest types to a limited range of scales. To examine these scales, we transformed the decay constants to measures of the distance at which the probability of forest meeting the 'core' and 'dominant' criteria was cut in half (S 1/2, m). S 1/2 for core forest was typically between ~55 and ~95 m depending on location along the river, indicating that core forest cover is restricted to extremely fine scales. In contrast, half of all dominant forest cover was lost at scales that were typically between ~525 and 750 m, but S 1/2 was as long as 1,800 m. S 1/2 is a simple measure that (1) condenses information derived from multi

  8. Environmental survey in the Tuul and Orkhon River basins of north-central Mongolia, 2010: metals and other elements in streambed sediment and floodplain soil.

    PubMed

    Brumbaugh, W G; Tillitt, D E; May, T W; Javzan, Ch; Komov, V T

    2013-11-01

    Streambed sediment and subsurface floodplain soil were sampled for elemental analyses from 15 locations in river basins of north-central Mongolia during August 2010. Our primary objective was to conduct a reconnaissance-level assessment of potential inputs of toxicologically important metals and metalloids to Lake Baikal, Russia, that might originate from mining and urban activities within tributaries of the Selenga River in Mongolia. Samples were collected in triplicate from all sites, then dried, and sieved to <2 mm for analysis by portable X-ray florescence spectroscopy and by inductively coupled plasma mass spectrometry after digestion with concentrated nitric and hydrochloric acids. Arsenic, copper, and mercury were greatly elevated in sediment and floodplain soil collected from tributary streams located near two major mining operations. Lead and zinc were moderately elevated in streambed sediment and in floodplain soil obtained from a small tributary in the capital city of Ulaanbaatar, but those concentrations were considerably less than probable effects benchmarks. Historical and possibly present mining activities have led to considerable metal contamination in certain tributaries of the Orkhon River in north-central Mongolia; however, metals originating from those sources did not appear to be accumulating in sediments at our downstream-most sampling sites located near the border between Mongolia and Russia. PMID:23685928

  9. Environmental survey in the Tuul and Orkhon River basins of north-central Mongolia, 2010: metals and other elements in streambed sediment and floodplain soi

    USGS Publications Warehouse

    Brumbaugh, William G.; Tillitt, Donald E.; May, Thomas W.; Choijil, J.; Komov, T.V.

    2013-01-01

    Streambed sediment and subsurface floodplain soil were sampled for elemental analyses from 15 locations in river basins of north-central Mongolia during August 2010. Our primary objective was to conduct a reconnaissance-level assessment of potential inputs of toxicologically important metals and metalloids to Lake Baikal, Russia, that might originate from mining and urban activities within tributaries of the Selenga River in Mongolia. Samples were collected in triplicate from all sites, then dried, and sieved to <2 mm for analysis by portable X-ray florescence spectroscopy and by inductively coupled plasma mass spectrometry after digestion with concentrated nitric and hydrochloric acids. Arsenic, copper, and mercury were greatly elevated in sediment and floodplain soil collected from tributary streams located near two major mining operations. Lead and zinc were moderately elevated in streambed sediment and in floodplain soil obtained from a small tributary in the capital city of Ulaanbaatar, but those concentrations were considerably less than probable effects benchmarks. Historical and possibly present mining activities have led to considerable metal contamination in certain tributaries of the Orkhon River in north-central Mongolia; however, metals originating from those sources did not appear to be accumulating in sediments at our downstream-most sampling sites located near the border between Mongolia and Russia.

  10. Flow regime effects on mature Populus fremontii (Fremont cottonwood) productivity on two contrasting dryland river floodplains

    USGS Publications Warehouse

    Andersen, Douglas C.

    2016-01-01

    I compared riparian cottonwood (Populus fremontii) productivity-discharge relationships in a relictual stand along the highly regulated Green River and in a naturally functioning stand along the unregulated Yampa River in semiarid northwest Colorado. I used multiple regression to model flow effects on annual basal area increment (BAI) from 1982 to 2011, after removing any autocorrelation present. Each BAI series was developed from 20 trees whose mean size (67 cm diameter at breast height [DBH]) was equivalent in the two stands. BAI was larger in the Yampa River stand except in 2 y when defoliating leaf beetles were present there. I found no evidence for a Yampa flood-magnitude threshold above which BAI declined. Flow variables explained ∼45% of residual BAI variability, with most explained by current-year maximum 90-d discharge (QM90) in the Yampa River stand and by a measure of the year-to-year change in QM90 in the Green River stand. The latter reflects a management-imposed ceiling on flood magnitude—Flaming Gorge Dam power plant capacity—infrequently exceeded during the study period. BAI in the relictual stand began to trend upward in 1992 when flows started to mimic a natural flow regime. Mature Fremont cottonwoods appear to be ecologically resilient. Their productivity along regulated rivers might be optimized using multiyear environmental flow designs.

  11. Floodplain Lakes: Evolution and Response

    NASA Astrophysics Data System (ADS)

    Hausmann, Sonja; Hall, Roland; Gell, Peter

    2011-05-01

    PAGES International Floodplain Lakes Workshop; Fayetteville, Arkansas, 16-19 September 2010 ; Human alteration of the major rivers and floodplains of the world is a global concern because they sustain aquatic ecosystems and supply food and energy to society. When in flood stage, the influence of a river extends across the floodplain and can revitalize productive wetlands. The condition of many rivers has declined worldwide, but the degree of degradation is hard to assess due to natural variability of flow and uncertainty of baseline status. Evidence of changes over decades to millennia in river and wetland conditions, however, can be quantified from physical, chemical, and biological information archived in the accumulated sediments of floodplain lakes.

  12. Abundance and biomass responses of microbial food web components to hydrology and environmental gradients within a floodplain of the River Danube.

    PubMed

    Palijan, Goran

    2012-07-01

    This study investigated the relationships of time-dependent hydrological variability and selected microbial food web components. Samples were collected monthly from the Kopački Rit floodplain in Croatia, over a period of 19 months, for analysis of bacterioplankton abundance, cell size and biomass; abundance of heterotrophic nanoflagellates and nanophytoplankton; and concentration of chlorophyll a. Similar hydrological variability at different times of the year enabled partition of seasonal effects from hydrological changes on microbial community properties. The results suggested that, unlike some other studies investigating sites with different connectivity, bacterioplankton abundance, and phytoplankton abundance and biomass increased during lentic conditions. At increasing water level, nanophytoplankton showed lower sensitivity to disturbance in comparison with total phytoplankton biomass: this could prolong autotrophic conditions within the floodplain. Bacterioplankton biomass, unlike phytoplankton, was not impacted by hydrology. The bacterial biomass less affected by hydrological changes can be an important additional food component for the floodplain food web. The results also suggested a mechanism controlling bacterial cell size independent of hydrology, as bacterial cell size was significantly decreased as nanoflagellate abundance increased. Hydrology, regardless of seasonal sucession, has the potential to structure microbial food webs, supporting microbial development during lentic conditions. Conversely, other components appear unaffected by hydrology or may be more strongly controlled by biotic interactions. This research, therefore, adds to understanding on microbial food web interactions in the context of flood and flow pulses in river-floodplain ecosystems.

  13. Spatial complexity reduces interaction strengths in the meta-food web of a river floodplain mosaic

    USGS Publications Warehouse

    Bellmore, James Ryan; Baxter, Colden Vance; Connolly, Patrick J.

    2015-01-01

    Theory states that both the spatial complexity of landscapes and the strength of interactions between consumers and their resources are important for maintaining biodiversity and the 'balance of nature.' Spatial complexity is hypothesized to promote biodiversity by reducing potential for competitive exclusion; whereas, models show weak trophic interactions can enhance stability and maintain biodiversity by dampening destabilizing oscillations associated with strong interactions. Here we show that spatial complexity can reduce the strength of consumer-resource interactions in natural food webs. By sequentially aggregating food webs of individual aquatic habitat patches across a floodplain mosaic, we found that increasing spatial complexity resulted in decreases in the strength of interactions between predators and prey, owing to a greater proportion of weak interactions and a reduced proportion of strong interactions in the meta-food web. The main mechanism behind this pattern was that some patches provided predation refugia for species which were often strongly preyed upon in other patches. If weak trophic interactions do indeed promote stability, then our findings may signal an additional mechanism by which complexity and stability are linked in nature. In turn, this may have implications for how the values of landscape complexity, and the costs of biophysical homogenization, are assessed.

  14. Records of pan (floodplain wetland) sedimentation as an approach for post-hoc investigation of the hydrological impacts of dam impoundment: The Pongolo river, KwaZulu-Natal.

    PubMed

    Heath, S K; Plater, A J

    2010-07-01

    River impoundment by dams has far-reaching consequences for downstream floodplains in terms of hydrology, water quality, geomorphology, ecology and ecosystem services. With the imperative of economic development, there is the danger that potential environmental impacts are not assessed adequately or monitored appropriately. Here, an investigation of sediment composition of two pans (floodplain wetlands) in the Pongolo River floodplain, KwaZulu-Natal, downstream of the Pongolapoort dam constructed in 1974, is considered as a method for post-hoc assessment of the impacts on river hydrology, sediment supply and water quality. Bumbe and Sokhunti pans have contrasting hydrological regimes in terms of their connection to the main Pongolo channel - Bumbe is a shallow ephemeral pan and Sokhunti is a deep, perennial water body. The results of X-ray fluorescence (XRF) geochemical analysis of their sediment records over a depth of >1 m show that whilst the two pans exhibit similar sediment composition and variability in their lower part, Bumbe pan exhibits a shift toward increased fine-grained mineral supply and associated nutrient influx at a depth of c. 45 cm whilst Sokhunti pan is characterised by increased biogenic productivity at a depth of c. 26 cm due to enhanced nutrient status. The underlying cause is interpreted as a shift in hydrology to a 'post-dam' flow regime of reduced flood frequencies with more regular baseline flows which reduce the average flow velocity. In addition, Sokhunti shows a greater sensitivity to soil influx during flood events due to the nature of its 'background' of autochthonous biogenic sedimentation. The timing of the overall shift in sediment composition and the dates of the mineral inwash events are not well defined, but the potential for these wetlands as sensitive recorders of dam-induced changes in floodplain hydrology, especially those with a similar setting to Sokhunti pan, is clearly demonstrated.

  15. Environmental education in the Upper Paraná River floodplain, municipality of Porto Rico (Paraná State), Brazil.

    PubMed

    Obara, A T; Suzuki, H I; Takemoto, R M; Tomanik, A; Corredato-Periotto, T R; Silva-Dias, M A G

    2009-06-01

    Since 2003, researchers, faculty, graduate and undergraduate students from the State University of Maringá have been working alongside teachers from the state and local schools in the municipality of Porto Rico (Paraná State), located on the banks of the Paraná River. Their objective is to outline actions and strategies with the purpose of building methodological paths to insert environmental education into the school curriculum. Based on the action-research methodology, the group has developed the following programs: a) the Continuing Education Program in Environmental Education; b) the Development of Interdisciplinary Projects; c) the Insertion of Information and Communication Technologies (ICTs); and d) the Production of Teaching Materials. The evaluations of the programs indicate that teachers have been able to gradually build a theoretical and methodological basis for environmental education while simultaneously growing into the role of teacher-researchers as they create the conditions to investigate their pedagogical practices, reflect upon them, share experiences, innovate, and make the teaching-learning process more significant. Allied to the advances in educational practices and with the aid of ICTs, the activities developed in the classroom, in the field and in the lab--all of which involve natural and cultural aspects of the region--have contributed to teachers' and students' better understanding of the ecological, cultural, social and economic value of the floodplain, and consequently, of the importance of preservation and management in order to maintain local biodiversity.

  16. Calibration Of 2D Hydraulic Inundation Models In The Floodplain Region Of The Lower Tagus River

    NASA Astrophysics Data System (ADS)

    Pestanana, R.; Matias, M.; Canelas, R.; Araujo, A.; Roque, D.; Van Zeller, E.; Trigo-Teixeira, A.; Ferreira, R.; Oliveira, R.; Heleno, S.

    2013-12-01

    In terms of inundated area, the largest floods in Portugal occur in the Lower Tagus River. On average, the river overflows every 2.5 years, at times blocking roads and causing important agricultural damages. This paper focus on the calibration of 2D-horizontal flood simulation models for the floods of 2001 and 2006 on a 70-km stretch of the Lower Tagus River. Flood extent maps, derived from ERS SAR and ENVISAT ASAR imagery were compared with the flood extent maps obtained for each simulation, to calibrate roughness coefficients. The combination of the calibration results from the 2001 and 2006 floods provided a preliminary Manning coefficient map of the study area.

  17. Calibration of 2D Hydraulic Inundation Models with SAR Imagery in the Floodplain Region of the Lower Tagus River

    NASA Astrophysics Data System (ADS)

    Pestana, Rita; Matias, Magda; Canelas, Ricardo; Roque, Dora; Araujo, Amelia; Van Zeller, Emilia; Trigo-Teixeira, Antonio; Ferreira, Rui; Oliveira, Rodrigo; Heleno, Sandra; Falcão, Ana Paula; Gonçalves, Alexandre B.

    2014-05-01

    Floods account for 40% of all natural hazards worldwide and were responsible for the loss of about 100 thousand human lives and affected more than 1,4 million people in the last decade of the 20th century alone. Floods have been the deadliest natural hazard in Portugal in the last 100 years. In terms of inundated area, the largest floods in Portugal occur in the Lower Tagus (LT) River. On average, the river overflows every 2.5 years, at times blocking roads and causing important agricultural damages. The economical relevance of the area and the high frequency of the relevant flood events make the LT floodplain a good pilot region to conduct a data-driven, systematic calibration work of flood hydraulic models. This paper focus on the calibration of 2D-horizontal flood simulation models for the floods of 1997, 2001 and 2006 on a 70-km stretch of the LT River, between Tramagal and Omnias, using the software Tuflow. This computational engine provides 2D solutions based on the Stelling finite-difference, alternating direction implicit (ADI) scheme that solves the full 2D free surface shallow-water flow equations and allowed the introduction of structures that constrain water flow. The models were based on a digital terrain model (DTM) acquired in 2008 by radar techniques (5m of spatial resolution) and on in situ measurements of water elevation in Omnias (downstream boundary condition) and discharge in Tramagal and Zezere (upstream boundary conditions). Due to the relevancy of several dykes on this stretch of the LT River, non-existent on the available DTM, five of them were introduced in the models. All models have the same boundaries and were simulated using steady-state flow initial conditions. The resolution of the 2D grid mesh was 30m. Land cover data for the study area was retrieved from Corine Land Cover 2006 (CO-ordination of INformation on the Environment) with spatial resolution of 100m, and combined with estimated manning coefficients obtained in literature

  18. Economic analysis of temperature reduction in a large river floodplain: An exploratory study of the WIllamette River, Oregon

    EPA Science Inventory

    This paper examines ecosystem restoration practices that focus on water temperature reductions in the upper mainstem Willamette River, Oregon, for the benefit of endangered salmonids and other native cold-water species. The analysis integrates hydrologic, natural science and eco...

  19. Lead exposure in passerines inhabiting lead-contaminated floodplains in the Coeur d'Alene River Basin, Idaho, USA

    USGS Publications Warehouse

    Johnson, G.D.; Audet, D.J.; Kern, J.W.; LeCaptain, L.J.; Strickland, M.D.; Hoffman, D.J.; McDonald, L.L.

    1999-01-01

    Blood collected from song sparrows (Melospiza melodia) and American robins (Turdus migratorius) captured with mist nets in a lead-contaminated (assessment) area and nearby uncontaminated (reference) areas within the Coeur d'Alene Basin in northern Idaho was analyzed for d-aminolevulinic acid dehydratase activity (ALAD) and hematocrit levels, and livers were analyzed for lead. Mean ALAD inhibition in the assessment area was 51% in song sparrows and 75% in American robins. The proportion of the sampled population with ALAD inhibition >50% was calculated to be 43% for song sparrows and 83% for American robins. Assessment area hematocrit values for song sparrows (0 = 39.9) and American robins (0 = 39.5) were lower than in reference areas (0 = 42.4 for song sparrows and 40.2 for American robins); however, differences were not statistically significant (p > 0.05). Significantly higher levels of lead (wet weight) were found in livers from song sparrows captured on the assessment area (0 = 1.93 ppm) than on reference areas (0 = 0.10 ppm) (p = 0.0079). Study results indicate that 43% (95% confidence interval [CI] = 12.9-77.5%) of the song sparrows and 83% (95% CI = 41.8-99.2%) of the American robins inhabiting the floodplain along the Coeur d'Alene River in the assessment area are being exposed to lead at levels sufficient to inhibit ALAD by > 50%. Variability in lead exposure indicators was attributed to high variability in environmental lead concentrations in the Coeur d'Alene River Basin.

  20. Factors influencing soil invertebrate communities in riparian grasslands of the central platte river floodplain

    USGS Publications Warehouse

    Davis, C.A.; Austin, J.E.; Buhl, D.A.

    2006-01-01

    In the Platte River Valley of central Nebraska, USA, riparian grasslands (also known as wet meadows) have been severely impacted by a reduction in river flows, causing lower ground-water levels and altered seasonal hydroperiods. The potential impacts of these hydrologic changes, as well as the environmental factors that influence wet meadow soil invertebrate communities, are not well understood. An understanding of the ecological processes that influence these invertebrate communities is crucial for maintaining and restoring wet meadows along the Platte River. Our objectives were to describe the soil invertebrate community of wet meadows throughout the growing season and to examine the relative roles of abiotic factors in determining patterns in invertebrate community structure. We conducted the study in 12 wet meadows along the Platte River during 1999 and 2000. We identified 73 invertebrate taxa; 39 were considered soil inhabitants. Total biomass was primarily composed of earthworms, Scarabaeidae, Isopoda, and Elateridae, with earthworms and Scarabaeidae accounting for >82%. Differences in river flow and precipitation patterns influenced some soil invertebrates. Earthworms and Scarabaeidae declined dramatically from 1999 (wet year) to 2000 (dry year). The topographic gradient created by the ridge-swale complex affected several soil invertebrate taxa; Scarabaeidae, Diplopoda, and Lepidoptera biomasses were greatest on drier ridges, while Tipulidae and Isopoda biomasscs were greatest in wetter sloughs. Responses of earthworm taxa to the topographic gradient were variable, but generally, greater biomasses occurred on ridges and mid-elevations. Water-table depth and soil moisture were the most important variables influencing wet meadow soil invertebrates. Because these communities are linked to the hydrologic processes of the Platte River, future alterations of wet meadow hydrology could shift the distribution patterns of many of these invertebrates and possibly

  1. Enhancing Floodplain Management in the Lower Mekong River Basin Using Vegetation and Water Cycle Satellite Observations

    NASA Astrophysics Data System (ADS)

    Bolten, J. D.; Spruce, J.; Wilson, R.; Strauch, K.; Doyle, T.; Srinivan, R.; Lakshmi, V.; Gupta, M.

    2014-12-01

    The Lower Mekong River Basin shared by China, Burma, Laos, Thailand, Cambodia, and Vietnam, is considered the lifeblood of Southeast Asia. The Mekong Basin is subject to large hydrological fluctuations on a seasonal and inter-annual basis. The basin remains prone to severe annual floods that continue to cause widespread damage and endanger food security and the livelihood of the millions who dwell in the region. Also the placement of newly planned dams primarily for hydropower in the Lower Mekong Basin may cause damaging social, agriculture and fisheries impacts to the region where we may now likely be at a critical 'tipping point'. The primary goal of this project is to apply NASA and USGS products, tools, and information for improved flood and water management in the Lower Mekong River Basin to help characterize, understand, and predict future changes on the basin. Specifically, we are providing and helping transfer to the Mekong River Commission (MRC) and the member countries of Thailand, Cambodia, Lao, Vietnam, and Burma the enhanced Soil and Water Assessment Tool (SWAT) using remotely sensed surface, ground water, and root zone soil moisture along with improved Land Use and Land Cover (LULC) maps. In order to estimate the flood potential and constrain the SWAT Available Water Capacity model parameter over the region, we are assimilated GRACE Terrestrial Water Storage observations into the Catchment Land Surface Model. In addition, a Graphic Visualization Tool (GVT) as been developed to work in concert with the output of the SWAT model parameterized for the Mekong Basin as an adjunct tool of the MRC Decision Support Framework. The project requires a close coordination of the development and assessment of the enhanced MRC SWAT with the guidance of MRC resource managers and technical advisors. This presentation will evaluate the skill of the enhanced SWAT model using qualitative (i.e., MODIS change detection) and quantitative (e.g., streamflow) metrics over one

  2. Geoinformatic and geophysical methods for evaluation of deposition and reworking of sediments with contaminants in floodplain of the Ploucnice River, Czech Republic

    NASA Astrophysics Data System (ADS)

    Elznicova, Jitka; Matys Grygar, Tomas; Kiss, Timea; Babek, Ondrej; Popelka, Jan; Plotnarek, Lukas; Tumova, Stepanka; Majerova, Lucie; Hosek, Michal

    2014-05-01

    Complex study for the deposition and remobilization of pollutants in floodplain of the Ploucnice River requires geoinformatic, geomorphologic, geophysical and geochemical knowledge. Geoinformatic tools are usable in several science disciplines. Photogrammetric methods are a big tool for land-use change development and digital surface model (DSM) reconstruction. The historical photographs from 1938 till 1994 were orthorectified using ERDAS 2013 LPS software. Historical and actual orthophotos were used to study the channel migration of the Ploucnice River and lateral shifts of the channel in the last 70 years. Historical digital surfer model, which is reconstructed from historical orthophotos with 60% overlaps, were used for 3D visualisation of historical landscape and shows land-use changes. Accurate digital elevation model (DEM) from laser scanning dataset was created for geomorphological analysis. Topography was analysed with GIS methods and the geomorphologic interpretation was then performed. The subsurface architecture of the floodplain and distribution of the sediment bodies were studied using electrical resistivity tomography (ERT). The Wenner-Schlumberger method with 104 electrodes in a single array was used. An inverse model resistivity section was produced from the apparent resistivity pseudosection by the least-square inversion method using RES2DINV software (Geotomo Software, Malaysia). The contamination of the floodplain was analysed with both field and laboratory instruments. The portable gamma-spectrometer DISA 400A was used for acquisition of the total surface gamma activity in field. Several hundreds of soil samples (from drill cores) and recent flood deposits (after 2013 flood) were analysed by laboratory X-ray fluorescence spectrometer to describe deposition and remobilization of pollutants in floodplain, of which most important are Ba, Ni, Pb, U and Zn. Geostatistical analysis was used for creation of a statistically valid prediction surface. The

  3. CHANGES IN 137 CS CONCENTRATIONS IN SOIL AND VEGETATION ON THE FLOODPLAIN OF THE SAVANNAH RIVER OVER A 30 YEAR PERIOD

    SciTech Connect

    Paller, M.; Jannik, T.; Fledderman, P.

    2007-12-12

    {sup 137}Cs released during 1954-1974 from nuclear production reactors on the Savannah River Site, a US Department of Energy nuclear materials production site in South Carolina, contaminated a portion of the Savannah River floodplain known as Creek Plantation. {sup 137}Cs activity concentrations have been measured in Creek Plantation since 1974 making it possible to calculate effective half-lives for {sup 137}Cs in soil and vegetation and assess the spatial distribution of contaminants on the floodplain. Activity concentrations in soil and vegetation were higher near the center of the floodplain than near the edges as a result of frequent inundation coupled with the presence of low areas that trapped contaminated sediments. {sup 137}Cs activity was highest near the soil surface, but depth related differences diminished with time as a likely result of downward diffusion or leaching. Activity concentrations in vegetation were significantly related to concentrations in soil. The plant to soil concentration ratio (dry weight) averaged 0.49 and exhibited a slight but significant tendency to decrease with time. The effective half-lives for {sup 137}Cs in shallow (0-7.6 cm) soil and in vegetation were 14.9 (95% CI = 12.5-17.3) years and 11.6 (95% CI = 9.1-14.1) years, respectively, and rates of {sup 137}Cs removal from shallow soil and vegetation did not differ significantly among sampling locations. Potential health risks on the Creek Plantation floodplain have declined more rapidly than expected on the basis of radioactive decay alone because of the relatively short effective half-life of {sup 137}Cs.

  4. Changes in 137Cs concentrations in soil and vegetation on the floodplain of the Savannah River over a 30 year period.

    PubMed

    Paller, M H; Jannik, G T; Fledderman, P D

    2008-08-01

    (137)Cs released during 1954-1974 from nuclear production reactors on the Savannah River Site, a US Department of Energy nuclear materials production site in South Carolina, contaminated a portion of the Savannah River floodplain known as Creek Plantation. (137)Cs activity concentrations have been measured in Creek Plantation since 1974 making it possible to calculate effective half-lives for (137)Cs in soil and vegetation and assess the spatial distribution of contaminants on the floodplain. Activity concentrations in soil and vegetation were higher near the center of the floodplain than near the edges as a result of frequent inundation coupled with the presence of low areas that trapped contaminated sediments. (137)Cs activity was highest near the soil surface, but depth related differences diminished with time as a likely result of downward diffusion or leaching. Activity concentrations in vegetation were significantly related to concentrations in soil. The plant to soil concentration ratio (dry weight) averaged 0.49 and exhibited a slight but significant tendency to decrease with time. The effective half-lives for (137)Cs in shallow (0-7.6 cm) soil and in vegetation were 14.9 (95% CI=12.5-17.3) years and 11.6 (95% CI=9.1-14.1) years, respectively, and rates of (137)Cs removal from shallow soil and vegetation did not differ significantly among sampling locations. Potential health risks on the Creek Plantation floodplain have declined more rapidly than expected on the basis of radioactive decay alone because of the relatively short effective half-life of (137)Cs.

  5. Adsorption and desorption of arsenic to aquifer sediment on the Red River floodplain at Nam Du, Vietnam

    NASA Astrophysics Data System (ADS)

    Thi Hoa Mai, Nguyen; Postma, Dieke; Thi Kim Trang, Pham; Jessen, Søren; Hung Viet, Pham; Larsen, Flemming

    2014-10-01

    The adsorption of arsenic onto aquifer sediment from the Red River floodplain, Vietnam, was determined in a series of batch experiments. Due to water supply pumping, river water infiltrates into the aquifer at the field site and has leached the uppermost aquifer sediments. The leached sediments remain anoxic but contain little reactive arsenic and iron, and are used in our experiments. The adsorption and desorption experiments were carried out by addition or removal of arsenic from the aqueous phase in sediment suspensions under strictly anoxic conditions. Also the effects of HCO3, Fe(II), PO4 and Si on arsenic adsorption were explored. The results show much stronger adsorption of As(V) as compared to As(III), full reversibility for As(III) adsorption and less so for As(V). The presence or absence of HCO3 did not influence arsenic adsorption. Fe(II) enhanced As(V) sorption but did not influence the adsorption of As(III) in any way. During simultaneous adsorption of As(III) and Fe(II), As(III) was found to be fully desorbable while Fe(II) was completely irreversibly adsorbed and clearly the two sorption processes are uncoupled. Phosphate was the only solute that significantly could displace As(III) from the sediment surface. Compiling literature data on arsenic adsorption to aquifer sediment in Vietnam and Bangladesh revealed As(III) isotherms to be almost identical regardless of the nature of the sediment or the site of sampling. In contrast, there was a large variation in As(V) adsorption isotherms between studies. A tentative conclusion is that As(III) and As(V) are not adsorbing onto the same sediment surface sites. The adsorption behavior of arsenic onto aquifer sediments and synthetic Fe-oxides is compared. Particularly, the much stronger adsorption of As(V) than of As(III) onto Red River as well as on most Bangladesh aquifer sediments, indicates that the perception that arsenic, phosphate and other species compete for the same surface sites of iron oxides in

  6. Effects of a diversion hydropower facility on the hydrological regime of the Correntes River, a tributary to the Pantanal floodplain, Brazil

    NASA Astrophysics Data System (ADS)

    Fantin-Cruz, Ibraim; Pedrollo, Olavo; Girard, Pierre; Zeilhofer, Peter; Hamilton, Stephen K.

    2015-12-01

    Facilities that produce hydroelectricity by diversion of part of the river's flow, which are often considered to have lower environmental impact than conventional hydropower dams, are being built in large numbers on river systems throughout the world, yet their cumulative impacts are not well understood. This study evaluated the hydrological effects of operation of a diversion hydropower facility on the Correntes River in Brazil (mean discharge 73 m3 s-1), which is potentially important because of the ecological implications for the floodplains of the Pantanal into which it flows. Many similar dams are built or proposed on rivers feeding the Pantanal. The 210-MW facility known as Ponte de Pedra diverts part of the river flow into a diversion channel in a nearly "run-of-river" design. The natural (reconstructed) and regulated (observed) flow regimes were characterized using Indicators of Hydrologic Alteration (IHA) and Flow Duration Curves (FDC). Seven parameters of IHA were significantly altered by the reservoir formation (magnitude of lowest monthly flow, minimum flows of 1, 3 and 7 days, maximum flow of 90 days and counts of high and low pulses). Among these, Principal Components Analysis identified the maximum flow of 90 days and the count of high flow pulses as integrators of hydrological alterations. The FDC showed that the reservoir also changed the seasonal regime of the flows, with greater changes in the lowest flow season. The reduction of river-floodplain connectivity and loss of associated ecosystem services are the major downstream ecological implications of this altered flow regime. To maintain the seasonal flooding regime while meeting the requirements for hydroelectric production, proposed limits for flow regime alterations are up to ±18% in low flow, ±24% in the rising limb and ±22% in high flow and the falling limb, relative to the natural flow. Operational changes to maintain flows with these limits could easily be implemented because the

  7. Reservoir floodplains support distinct fish assemblages

    USGS Publications Warehouse

    Miranda, Leandro E.; Wigen, S. L.; Dagel, Jonah D.

    2014-01-01

    Reservoirs constructed on floodplain rivers are unique because the upper reaches of the impoundment may include extensive floodplain environments. Moreover, reservoirs that experience large periodic water level fluctuations as part of their operational objectives seasonally inundate and dewater floodplains in their upper reaches, partly mimicking natural inundations of river floodplains. In four flood control reservoirs in Mississippi, USA, we explored the dynamics of connectivity between reservoirs and adjacent floodplains and the characteristics of fish assemblages that develop in reservoir floodplains relative to those that develop in reservoir bays. Although fish species richness in floodplains and bays were similar, species composition differed. Floodplains emphasized fish species largely associated with backwater shallow environments, often resistant to harsh environmental conditions. Conversely, dominant species in bays represented mainly generalists that benefit from the continuous connectivity between the bay and the main reservoir. Floodplains in the study reservoirs provided desirable vegetated habitats at lower water level elevations, earlier in the year, and more frequently than in bays. Inundating dense vegetation in bays requires raising reservoir water levels above the levels required to reach floodplains. Therefore, aside from promoting distinct fish assemblages within reservoirs and helping promote diversity in regulated rivers, reservoir floodplains are valued because they can provide suitable vegetated habitats for fish species at elevations below the normal pool, precluding the need to annually flood upland vegetation that would inevitably be impaired by regular flooding. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  8. How are River Discharge - Suspended Sediment Relations Influenced by Watershed and Channel-Floodplain Morphology?

    NASA Astrophysics Data System (ADS)

    Vaughan, A. A.; Belmont, P.

    2015-12-01

    Erosion, transport and deposition of fine sediment (clay, silt and fine sand) influence the form and function of river systems. Excess suspended sediment degrades stream ecosystems and is implicated as a leading cause of water quality and aquatic life impairment. Consequently, understanding the factors that control fine sediment transport regimes is an interesting topic for basic science and one that has important management and policy implications. Fine sediment is mostly transported in suspension as a non-capacity load; transport rates are dependent on sediment supply in addition to a river's transport capacity. Many studies have investigated watershed-scale topographic, hydrologic, climatic, and land use influences on fine sediment erosion and transport regimes. Several recent studies in a wide range of landscapes have demonstrated that the majority of suspended sediment may be sourced from the near-channel environment; therefore, near-channel morphological characteristics may provide better predictive power compared to watershed averages. This study analyzes recent total suspended solids (TSS) data from 45 gages on 35 separate rivers. The rivers span the state of Minnesota, draining basins ranging from 33 km2 to 68100 km2 with distinct settings in terms of topography, land cover, hydrology and geologic history. We generate rating curves of the form TSS = aQb, where Q is normalized discharge and a and b are parameters that describe the shape of the relations. Values of a range from 4 to 138 mg/L; b values range from -0.53 to 1.86. We use high resolution lidar topography data to characterize the near-channel environment upstream of gages. In addition to commonly studied metrics describing the topographic, climatic/hydrologic and land use setting of the basin, we extract near-channel morphometrics that we hypothesize to influence fine sediment generation and transport: the difference in height of banks/bluffs (a measure of the amount of material available to be

  9. Estimates of river flows, floodplain inundation and land-atmosphere feedbacks in tropical African wetlands

    NASA Astrophysics Data System (ADS)

    Dadson, Simon; Hayman, Garry; MacKellar, Neil

    2013-04-01

    The regional response of African rivers and wetlands to climate variability and change is of interest to hydrologists, meteorologists and water resource planners. Over wet surfaces, high daytime evaporation rates and suppressed sensible heat fluxes induce a shallower, moister planetary boundary layer, which affects atmospheric instability and favours the initiation of new storms. Moreover, wetlands form a key link between the hydrological and carbon cycles, via anoxic degradation of organic matter to release methane (CH4). Wetlands are the largest, but least well quantified, single source of CH4, with emissions ranging from 105-278 Tg yr-1, approximately 75 percent of which comes from the tropics. Yet little is known about the ability of regional models to reproduce regional patterns of hydrological response to climate variability and change in Africa, and few studies have directly addressed the impact of fluvial inundation on water, energy and carbon fluxes between the atmosphere and the land surface. Here we use the Joint UK Land-Environment Simulator (JULES) land surface model to produce estimates of river flows over Africa. The hydrological component of this model comprises a probability-distributed model of soil moisture and runoff production coupled with a discrete approximation to the one-dimensional kinematic wave equation to route river water downslope. We use subgrid-resolution topographic data to derive a two-parameter frequency distribution of inundated areas for each grid box which we then employ to represent overbank inundation in the model. The model was configured at 0.5 degree resolution and driven using the WATCH Forcing Data (WFD; Weedon et al., 2011) which is based on ERA-40 reanalysis data and an alternative based on applying the WFD methodology to ERA-Interim data (WFDEI; Weedon et al., 2012). The model reproduces the salient features of the observed river flow and inundation patterns; these include substantial evaporative losses from

  10. Dissolved organic carbon lability increases with water residence time in the alluvial aquifer of a river floodplain ecosystem

    NASA Astrophysics Data System (ADS)

    Helton, Ashley M.; Wright, Meredith S.; Bernhardt, Emily S.; Poole, Geoffrey C.; Cory, Rose M.; Stanford, Jack A.

    2015-04-01

    We assessed spatial and temporal patterns of dissolved organic carbon (DOC) lability and composition throughout the alluvial aquifer of the 16 km2 Nyack Floodplain in northwest Montana, USA. Water influx to the aquifer derives almost exclusively from the Middle Fork of the Flathead River, and water residence times within the aquifer range from days to months. Across seasons and channel discharge conditions, we measured DOC concentration, lability, and optical properties of aquifer water sampled from 12 wells, both near and ~3 m below the water table. Concentrations of DOC were typically low (542 ± 22.7 µg L-1; mean ± se), and the percentage of labile DOC averaged 18 ± 12% during 3 day laboratory assays. Parallel factor analysis of fluorescence excitation-emission matrices revealed two humic-like and two amino acid-like fluorescence groups. Total DOC, humic-like components, and specific UV absorbance decreased with water residence time, consistent with sorption to aquifer sediments. However, labile DOC (both concentration and fraction) increased with water residence time, suggesting a concurrent influx or production of labile DOC. Thus, although the carbon-poor, oxygen-rich aquifer is a net sink for DOC, recalcitrant DOC appears to be replaced with more labile DOC along aquifer flow paths. Our observation of DOC production in long flow paths contrasts with studies of hyporheic DOC consumption along short (centimeters to meters) flow paths and highlights the importance of understanding the role of labile organic matter production and/or influx in alluvial aquifer carbon cycling.

  11. Transfer of mercury and methylmercury along macroinvertebrate food chains in a floodplain lake of the Beni River, Bolivian Amazonia.

    PubMed

    Molina, Carlos Israel; Gibon, François-Marie; Duprey, Jean-Louis; Dominguez, Eduardo; Guimarães, Jean-Remy D; Roulet, Marc

    2010-07-15

    We have evaluated the mercury and methylmercury transfers to and within the macroinvertebrate communities of a floodplain lake of the Beni River basin, Bolivia, during three hydrological seasons and in two habitats (open water and vegetation belt). Using the stable isotopes delta(13)C and delta(15)N, six trophic chains were identified during a previous study. Four are based on only one source: seston, organic matter from the bottom sediment, periphyton and macrophytes. Two are based on mixed sources (seston and periphyton in one case, periphyton and macrophytes in the other). During sampling, we found only one taxon that had surface sediment organic matter as food source and very few taxa whose trophic source was constituted by macrophytes. The periphyton was the most important source during all seasons; it produced the longest chain, with three trophic positions. Whatever the season and trophic source, all collected macroinvertebrates contained methyl mercury and the latter was biomagnified in all trophic chains that we identified. The biomagnification of methylmercury through invertebrate trophic chains accurately reflected the existence and length of these chains. Biomagnification was virtually non-existent in the sediment-based chain, low and restricted to the dry season in the macrophyte-based chain. It was significant in the seston-based chain, but limited by the existence of only two trophic levels and restricted to the wet season. Finally, it was very effective in the periphyton-based chain, which offers the highest rate of contamination of the source but, above all, the largest number of trophic levels.

  12. Passerine exposure to primarily PCDFs and PCDDs in the river floodplains near Midland, Michigan, USA.

    PubMed

    Fredricks, Timothy B; Zwiernik, Matthew J; Seston, Rita M; Coefield, Sarah J; Plautz, Stephanie C; Tazelaar, Dustin L; Shotwell, Melissa S; Bradley, Patrick W; Kay, Denise P; Giesy, John P

    2010-05-01

    House wren (Troglodytes aedon), tree swallow (Tachycineta bicolor), and eastern bluebird (Sialia sialis) tissues collected in study areas (SAs) downstream of Midland, Michigan (USA) contained concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) greater than in upstream reference areas (RAs) in the region. The sum of concentrations of PCDD/DFs (SigmaPCDD/DFs) in eggs of house wrens and eastern bluebirds from SAs were 4- to 22-fold greater compared to those from RAs, whereas concentrations in tree swallow eggs were similar among areas. Mean concentrations of SigmaPCDD/DFs and sum 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (SigmaTEQs(WHO-Avian)), based on 1998 WHO avian toxic equivalency factors, in house wren and eastern bluebird eggs ranged from 860 (430) to 1500 (910) ng/kg wet weight (ww) and 470 (150) to 1100 (510) ng/kg ww, respectively, at the most contaminated study areas along the Tittabawassee River, whereas mean concentrations in tree swallow eggs ranged from 280 (100) to 760 (280) ng/kg ww among all locations. Concentrations of SigmaPCDD/DFs in nestlings of all studied species at SAs were 3- to 50-fold greater compared to RAs. Mean house wren, tree swallow, and eastern bluebird nestling concentrations of SigmaPCDD/DFs and SigmaTEQs(WHO-Avian) ranged from 350 (140) to 610 (300) ng/kg ww, 360 (240) to 1100 (860) ng/kg ww, and 330 (100) to 1200 (690) ng/kg ww, respectively, at SAs along the Tittabawassee River. Concentrations of SigmaTEQs(WHO-Avian) were positively correlated with SigmaPCDD/DF concentrations in both eggs and nestlings of all species studied. Profiles of relative concentrations of individual congeners were dominated by furan congeners (69-84%), primarily 2,3,7,8-tetrachlorodibenzofuran and 2,3,4,7,8-pentachlorodibenzofuran, for all species at SAs on the Tittabawassee and Saginaw rivers but were dominated by dioxin congeners at upstream RAs.

  13. Passerine Exposure to Primarily PCDFs and PCDDs in the River Floodplains Near Midland, Michigan, USA

    PubMed Central

    Zwiernik, Matthew J.; Seston, Rita M.; Coefield, Sarah J.; Plautz, Stephanie C.; Tazelaar, Dustin L.; Shotwell, Melissa S.; Bradley, Patrick W.; Kay, Denise P.; Giesy, John P.

    2009-01-01

    House wren (Troglodytes aedon), tree swallow (Tachycineta bicolor), and eastern bluebird (Sialia sialis) tissues collected in study areas (SAs) downstream of Midland, Michigan (USA) contained concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) greater than in upstream reference areas (RAs) in the region. The sum of concentrations of PCDD/DFs (ΣPCDD/DFs) in eggs of house wrens and eastern bluebirds from SAs were 4- to 22-fold greater compared to those from RAs, whereas concentrations in tree swallow eggs were similar among areas. Mean concentrations of ΣPCDD/DFs and sum 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (ΣTEQsWHO-Avian), based on 1998 WHO avian toxic equivalency factors, in house wren and eastern bluebird eggs ranged from 860 (430) to 1500 (910) ng/kg wet weight (ww) and 470 (150) to 1100 (510) ng/kg ww, respectively, at the most contaminated study areas along the Tittabawassee River, whereas mean concentrations in tree swallow eggs ranged from 280 (100) to 760 (280) ng/kg ww among all locations. Concentrations of ΣPCDD/DFs in nestlings of all studied species at SAs were 3- to 50-fold greater compared to RAs. Mean house wren, tree swallow, and eastern bluebird nestling concentrations of ΣPCDD/DFs and ΣTEQsWHO-Avian ranged from 350 (140) to 610 (300) ng/kg ww, 360 (240) to 1100 (860) ng/kg ww, and 330 (100) to 1200 (690) ng/kg ww, respectively, at SAs along the Tittabawassee River. Concentrations of ΣTEQsWHO-Avian were positively correlated with ΣPCDD/DF concentrations in both eggs and nestlings of all species studied. Profiles of relative concentrations of individual congeners were dominated by furan congeners (69–84%), primarily 2,3,7,8-tetrachlorodibenzofuran and 2,3,4,7,8-pentachlorodibenzofuran, for all species at SAs on the Tittabawassee and Saginaw rivers but were dominated by dioxin congeners at upstream RAs. Electronic supplementary material The online version of this article (doi:10

  14. Distribution patterns, population status and conservation of Melanosuchus niger and Caiman yacare (Crocodylia, Alligatoridae) in oxbow lakes of the Ichilo river floodplain, Bolivia.

    PubMed

    Aguilera, Ximena; Coronel, Jorge S; Thierry, Oberdorff; Van Damme, Paul A

    2008-06-01

    Caiman yacare (lagarto) and Melanosuchus niger (black caiman), sympatric species in the Bolivian Amazon basin, have been severely overexploited in the past. We present the results of a standardized survey of C. yacare and M. niger populations in order to evaluate their actual population status in twelve oxbow lakes of the Ichilo River floodplain. Additionally we explored the effect of environmental and anthropogenic variables on caiman distribution patterns. The average density of C yacare and M niger in the shoreline of floodplain lakes was of 6 and 1 ind/km, respectively. For both species, the population was composed mainly of juvenile individuals. We used regression tree analysis (RTA) to assess patterns of M. niger and C. yacare densities with eight environmental and two anthropogenic variables. The RTA analysis showed that the variation in the densities of both C. yacare (52.4%) and M. niger (36.8 %) was related to water conductivity. For C yacare, higher densities occurred at higher values of water conductivity, while M. niger densities followed an opposite trend, resulting in relatively well spatially segregated populations of the two species. After excluding conductivity, Lake-River Distance (LRD) was shown to be the main splitting variable in the RTA analysis. The observed distribution patterns may be the result of the historical post-hunting situation, in combination with differences in habitat selection by the two species, and competitive exclusion processes between the two species. M. niger, a species reported to be recovering slowly from previous low population levels, appears relatively well protected in the Ichilo river floodplain. PMID:19256453

  15. Water balance analysis of the Morava River floodplain in the Kostice-Lanžhot transect using the WBCM-7 model.

    PubMed

    Kovář, Pavel; Heřmanovská, Darina; Hadaš, Pavel; Hrabalíková, Michaela; Pešková, Jitka

    2016-02-01

    The study area of the Morava River floodplain is situated between the rivers Morava and Kyjovka in the reach from Hodonín to Lanžhot. This experimental area was chosen because during the last 30 years, there has been a serious problem with the frequent occurrence of hydrological extremes, such as floods and droughts. Dry seasons have a very negative impact on the floodplain forest and have been caused mainly by regulation of the Morava River channel in the 1970s. Since flooding in the catastrophic year 1977, a part of this area has served as a polder for flood impact mitigation of the urbanised area of the town of Lanžhot. Management and farming practices have been heavily affected by the enormous economic and ecological damage due to long-term flooding of agricultural land. The purpose of this study is to assess the extent to which the precipitation in the growing season of the dry years 2003 and 2011 was deficient, in comparison with the normal year 2009, through a study of the actual evapotranspiration caused by the significant drought in the Morava floodplain. A similar but converse situation in the wet year 2010 was also analysed, with the aim to show the differences in the components of the water balance equation in the growing seasons of all the extreme years tested here. The daily data from the Kostice climatological station were processed using the WBCM-7 model, where the input parameters were calibrated by the fluctuation of the groundwater table in the control borehole.

  16. Water balance analysis of the Morava River floodplain in the Kostice-Lanžhot transect using the WBCM-7 model.

    PubMed

    Kovář, Pavel; Heřmanovská, Darina; Hadaš, Pavel; Hrabalíková, Michaela; Pešková, Jitka

    2016-02-01

    The study area of the Morava River floodplain is situated between the rivers Morava and Kyjovka in the reach from Hodonín to Lanžhot. This experimental area was chosen because during the last 30 years, there has been a serious problem with the frequent occurrence of hydrological extremes, such as floods and droughts. Dry seasons have a very negative impact on the floodplain forest and have been caused mainly by regulation of the Morava River channel in the 1970s. Since flooding in the catastrophic year 1977, a part of this area has served as a polder for flood impact mitigation of the urbanised area of the town of Lanžhot. Management and farming practices have been heavily affected by the enormous economic and ecological damage due to long-term flooding of agricultural land. The purpose of this study is to assess the extent to which the precipitation in the growing season of the dry years 2003 and 2011 was deficient, in comparison with the normal year 2009, through a study of the actual evapotranspiration caused by the significant drought in the Morava floodplain. A similar but converse situation in the wet year 2010 was also analysed, with the aim to show the differences in the components of the water balance equation in the growing seasons of all the extreme years tested here. The daily data from the Kostice climatological station were processed using the WBCM-7 model, where the input parameters were calibrated by the fluctuation of the groundwater table in the control borehole. PMID:26733468

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Geomorphological studies of floodplains provide relevant data about evolutions of fluvial landscape over long time-scales and allow a better understanding of palaeo-environnemental evolutions. The Cher River flows from the "Massif Central" to its junction with the Loire River in the South of the "Bassin de Paris". The long-term fluvial evolutions since the LGM of this medium-sized catchment, are not well documented. However, a first prospection revealed a high potential of fluvial archives. The aim of the present work is to provide elements to characterize past fluvial dynamics based on the analysis of inherited landforms (mainly palaeo-channels) and sedimentary bodies located in the floodplain, using hydrogeomorphological methods. Data are acquired through the analysis of DEM LiDAR, geophysical methods (electric tomography) and cores (boreholes) collected in the floodplain. The analysis of DEM LiDAR and morpho-sedimentary observations yields palaeo-hydrographical reconstructions and allows two generations of topographic and sedimentary fluvial inheritances to be identified. Most ancient fluvial landforms correspond to mounds slightly higher than the floodplain level, incised by wide and shallow palaeo-channels. A second fluvial pattern, more recent, is characterized by palaeo-meanders. Measuring the width, the amplitude and the curvature, we show that some of the palaeo-meanders are much larger, wider and more sinuous than the current meanders, showing changes in past flow regime. The analysis of the filling of palaeo-channels allows us to identify firstly the transverse and longitudinal geometry of former channels. These data help us to estimate bank-full discharge of palaeo-channels. Secondly, the morpho-sedimentary analysis highlights their post-abandonment environmental changes. Three main stratigraphic units are identified. (1) At the base, there is medium and coarse sand attributed to fluvial transport. (2) It is overlain by a layer composed of organo

  18. Strong effects of predation by fishes on an invasive macroinvertebrate in a large floodplain river

    USGS Publications Warehouse

    Bartsch, M.R.; Bartsch, L.A.; Gutreuter, S.

    2005-01-01

    We assessed the effects of fish predation on zebra mussels (Dreissena polymorpha) in Navigation Pool 8 of the Upper Mississippi River from 13 May to 5 October, 1998. Concrete-block samplers were deployed at 18 randomly chosen sites in the main-channel border, with 6 sites in the upper, middle, and lower segments of the pool. Two blocks, 1 of which was enclosed in a cage to exclude large predatory fishes, were deployed at each site. After 145 d, blocks were retrieved from 12 of the 18 sites, and zebra mussels were found on all blocks. Densities of zebra mussels were higher on caged blocks than uncaged blocks, and the magnitudes of the differences varied spatially. Mean mussel densities on uncaged blocks were reduced by 66%, 86%, and 20% compared to caged blocks in the upper, middle, and lower pool segments, respectively, over the 145-d interval. Mean daily instantaneous zebra mussel mortality rates from large predators ranged from 0.0016 to 0.0138. Similarly, biomass of zebra mussels was higher on caged than uncaged blocks. Mean mussel biomass on uncaged blocks was reduced by 64% pool-wide, relative to biomass on caged blocks. Zebra mussels were consumed by at least 6 fish taxa including redhorse stickers (Moxostoma spp.), common carp (Cyprinus carpio), bluegill (Lepomis macrochirus), quillback carpsucker (Carpiodes cyprinus), flathead catfish (Pylodictis olivaris), and freshwater drum (Aplodinotus grunniens). Fish predation had an important moderating effect on zebra mussel demography in Pool 8.

  19. Bioavailability of sediment-associated mercury to Hexagenia mayflies in a contaminated floodplain river

    USGS Publications Warehouse

    Naimo, T.J.; Wiener, J.G.; Cope, W.G.; Bloom, N.S.

    2000-01-01

    We examined the bioavailability of mercury in sediments from the contaminated Sudbury River (Massachusetts, U.S.A.). Mayfly nymphs (Hexagenia) were exposed in four 21-day bioaccumulation tests to contaminated and reference sediments (treatments) from reservoirs, flowing reaches, palustrine wetlands, and a riverine lake. Mean total mercury (Sigma Hg) ranged from 880 to 22 059 ng.g dry weight(-1) in contaminated sediments and from 90 to 272 ng.g(-1) in reference sediments. Mean final concentrations of methyl mercury (MeHg) in test water were greatest (8-47 ng Hg.L-1) in treatments with contaminated wetland sediments, which had mean Sigma Hg ranging from 1200 to 2562 ng.g(-1). In mayflies, final mean concentrations of MeHg were highest in treatments with contaminated wetland sediments (122-183 ng Hg.g(-1)), intermediate in treatments with contaminated sediments from reservoirs, flowing reaches, and a riverine lake (75-127 ng Hg.g(-1)), and lowest in treatments with reference sediments (32-41 ng Hg.g(-1)). We conclude that the potential entry of MeHg into the benthic food chain was greater in contaminated palustrine wetlands than in the contaminated reservoirs, which had the most contaminated sediments.

  20. Inter- and intraspecific variation in mercury bioaccumulation by snakes inhabiting a contaminated river floodplain.

    PubMed

    Drewett, David V V; Willson, John D; Cristol, Daniel A; Chin, Stephanie Y; Hopkins, William A

    2013-04-01

    Although mercury (Hg) is a well-studied contaminant, knowledge about Hg accumulation in snakes is limited. The authors evaluated Hg bioaccumulation within and among four snake species (northern watersnakes, Nerodia sipedon; queen snakes, Regina septemvittata; common garter snakes, Thamnophis sirtalis; and rat snakes, Elaphe obsoleta [Pantherophis alleghaniensis]) from a contaminated site on the South River (Waynesboro, VA, USA) and two nearby reference sites. Total Hg (THg) concentrations in northern watersnake tail tissue at the contaminated site ranged from 2.25 to 13.84 mg/kg dry weight (mean: 4.85 ± 0.29), or 11 to 19 times higher than reference sites. Blood THg concentrations (0.03-7.04 mg/kg wet wt; mean: 2.24 ± 0.42) were strongly correlated with tail concentrations and were the highest yet reported in a snake species. Within watersnakes, nitrogen stable isotope values indicated ontogenetic trophic shifts that correlated with THg bioaccumulation, suggesting that diet plays a substantial role in Hg exposure. Female watersnakes had higher mean THg concentrations (5.67 ± 0.46 mg/kg) than males (4.93 ± 0.49 mg/kg), but no significant differences between sexes were observed after correcting for body size. Interspecific comparisons identified differences in THg concentrations among snake species, with more aquatic species (watersnakes and queen snakes) accumulating higher mean concentrations (5.60 ± 0.40 and 4.59 ± 0.38 mg/kg in tail tissue, respectively) than the more terrestrial species, garter snakes and rat snakes (1.28 ± 0.32 and 0.26 ± 0.09 mg/kg, respectively). The results of the present study warrant further investigation of potential adverse effects and will aid in prioritizing conservation efforts.

  1. Hydrology, vegetation, and soils of riverine and tidal floodplain forests of the lower Suwannee River, Florida, and potential impacts of flow reductions

    USGS Publications Warehouse

    Light, Helen M.; Darst, Melanie R.; Lewis, Lori J.; Howell, David A.

    2002-01-01

    A study relating hydrologic conditions, soils, and vegetation of floodplain forests to river flow was conducted in the lower Suwannee River, Florida, from 1996 to 2000. The study was done by the U.S. Geological Survey in cooperation with the Suwannee River Water Management District to help determine the minimum flows and levels required for wetlands protection. The study area included forests within the 10-year floodplain of the Suwannee River from its confluence with the Santa Fe River to the tree line (lower limit of forests) near the Gulf of Mexico, and covered 18,600 hectares (ha) of forests, 75 percent of which were wetlands and 25 percent uplands. The floodplain was divided into three reaches, riverine, upper tidal, and lower tidal, based on changes in hydrology, vegetation, and soils with proximity to the coast. The Suwannee River is the second largest river in Florida in terms of average discharge. Median flow at the confluence of the Suwannee and Santa Fe Rivers is approximately 181 cubic meters per second (m3/s) or 6,480 cubic feet per second (ft3/s) (1933-99). At the upper end of the riverine reach, river stages are unaffected by tides and have a typical annual range of 4.1 meters (m). Tides affect river stages at low and medium flows in the upper tidal reach, and at all flows in the lower tidal reach. Median tidal range at the mouth of the Suwannee River is about 1 m. Salinity of river water in the lower tidal reach increases with decreasing flow and proximity to the Gulf of Mexico. Vertically averaged salinity in the river near the tree line is typically about 5 parts per thousand at medium flow. Land-surface elevation and topographic relief in the floodplain decrease with proximity to the coast. Elevations range from 4.1 to 7.3 m above sea level at the most upstream riverine transect and from 0.3 to 1.3 m above sea level on lower tidal transects. Surface soils in the riverine reach are predominantly mineral and dry soon after floods recede except in

  2. Relation of sediment load and flood-plain formation to climatic variability, Paria River drainage basin, Utah and Arizona

    USGS Publications Warehouse

    Graf, J.B.; Webb, R.H.; Hereford, R.

    1991-01-01

    Flood-plain alluviation began about 1940 at a time of decreasing magnitude and frequency of floods in winter, summer, and fall. No floods with stages high enough to inundate the flood plain have occurred since 1980, and thus no flood-plain alluviation has occurred since then. The decrease in magnitude and frequency of floods appears to have resulted from a decrease in frequency of large storms, particularly dissipating tropical cyclones, and not from a decrease in annual or seasonal precipitation. -from Authors

  3. Threshold effects of flood duration on the vegetation and soils of the Upper Mississippi River floodplain, USA

    USGS Publications Warehouse

    De Jager, Nathan R.; Thomsen, Meredith; Yin, Yao

    2012-01-01

    Our results suggest that there is a threshold along the elevation gradient of this floodplain, corresponding with flood durations lasting ~40% of the growing season. At lower elevation sites, flooding exerts primary control over forest soils and vegetation, restricting the former to silt plus clay with higher organic matter and the latter to a few highly flood tolerant species. The existence of such thresholds have implications for management of floodplain soil nutrient dynamics and plant diversity under existing hydrologic regimes, more natural hydrologic regimes and more extreme hydrologic regimes that may result from climate change.

  4. Phytotoxicity of floodplain soils contaminated with trace metals along the Clark Fork River, Grant-Kohrs Ranch National Historic Site, Deer Lodge, Montana, USA

    SciTech Connect

    Rader, B.R.; Nimmo, D.W.R.; Chapman, P.L.

    1997-07-01

    Concentrations of metals in sediments and soils deposited along the floodplain of the Clark Fork River, within the Grant-Kohrs Ranch National Historic Site, Deer Lodge, Montana, USA, have exceeded maximum background concentrations in the United States for most metals tested. As a result of mining and smelting activities, portions of the Deer Lodge Valley, including the Grant-Kohrs Ranch, have received National Priority List Designation under the Comprehensive Environmental Response, Compensation and Liability Act. Using a series of plant germination tests, pH measurements, and metal analyses, this study investigated the toxicity of soils from floodplain slicken areas, bare spots devoid of vegetation, along the Clark Fork River. The slicken soils collected from the Grant-Kohrs Ranch were toxic to all four plant species tested. The most sensitive endpoint in the germination tests was root length and the least sensitive was emergence. Considering emergence, the most sensitive species was the resident grass species Agrostis gigantea. The sensitivities were reversed when root lengths were examined, with Echinochloa crusgalli showing the greatest sensitivity. Both elevated concentrations of metals and low pH were necessary to produce an acutely phytotoxic response in laboratory seed germination tests using slicken soils. Moreover, pH values on the Grant-Kohrs Ranch appear to be a better predictor of acutely phytotoxic conditions than total metal levels.

  5. Phytotoxicity of floodplain soils contaminated with trace metals along the clark fork river, Grant-Kohrs Ranch National Historic Site, Deer Lodge, Montana, United States

    USGS Publications Warehouse

    Rader, B.R.; Nimmo, D.W.R.; Chapman, P.L.

    1997-01-01

    Concentrations of metals in sediments and soils deposited along the floodplain of the Clark Fork River, within the Grant-Kohrs Ranch National Historic Site, Deer Lodge, Montana, USA, have exceeded maximum background concentrations in the United States for most metals tested. As a result of mining and smelting activities, portions of the Deer Lodge Valley, including the Grant-Kohrs Ranch, have received National Priority List Designation under the Comprehensive Environmental Response, Compensation and Liability Act. Using a series of plant germination tests, pH measurements, and metal analyses, this study investigated the toxicity of soils from floodplain 'slicken' areas, bare spots devoid of vegetation, along the Clark Fork River. The slicken soils collected from the Grant-Kohrs Ranch were toxic to all four plant species tested. The most sensitive endpoint in the germination tests was root length and the least sensitive was emergence. Considering emergence, the most sensitive species was the resident grass species Agrostis gigantea. The sensitivities were reversed when root lengths were examined, with Echinochloa crusgalli showing the greatest sensitivity. Both elevated concentrations of metals and low pH were necessary to produce an acutely phytotoxic response in laboratory seed germination tests using slicken soils. Moreover, pH values on the Grant-Kohrs Ranch appear to be a better predictor of acutely phytotoxic conditions than total metal levels.

  6. Effects of the flood regime on the body condition of fish of different trophic guilds in the Upper Paraná River floodplain, Brazil.

    PubMed

    Abujanra, F; Agostinho, A A; Hahn, N S

    2009-06-01

    In this study, we evaluated the influence of various hydrological cycles on the feeding body condition of fish species of different trophic guilds in the Paraná River floodplain, as well as the impacts of upstream impoundments on fish conditions. Attributes of the river floods (duration, time of year, intensity, and variability in a given year) and the body condition, measured by the mean residuals of length-weight ratios, of the detritivorous, herbivorous, insectivorous, invertivores, omnivorous, piscivorous, and planktivorous species were evaluated. Fish were sampled during a period before (1986-1994) and after (2000-2004) the completion of filling of the Porto Primavera Reservoir, which is located upstream from the floodplain area under study. Three sub-basins in the floodplain were sampled: the Ivinheima River, which has no dams; the Paraná River, which has several dams; and the Baia River, which is influenced by the Paraná. A two-way ANOVA identified significant variations in mean body conditions for localities and for the hydrological cycles, and the interactions were also significant. The findings revealed that before the Porto Primavera Reservoir was filled, the body condition of the feeding guilds varied similarly in the three sub basins, but this pattern was not observed after filling was completed. However, in years with minor or no floods, the body condition was high, especially in the sub-basins influenced by Porto Primavera (Paraná and Baía). Pearson's and Spearman's correlations showed that most effects of the floods were unfavorable to the body condition of the guilds, except for the annual variation in water level, which aids herbivores in accessing allochthonous food resources. Detritivores were negatively affected by all flood attributes. A correlation between the relative stomach weight (mean residual of the ratio of total and stomach weights) and the body condition demonstrated the poor relationship between the amount of food intake and

  7. Effects of the flood regime on the body condition of fish of different trophic guilds in the Upper Paraná River floodplain, Brazil.

    PubMed

    Abujanra, F; Agostinho, A A; Hahn, N S

    2009-06-01

    In this study, we evaluated the influence of various hydrological cycles on the feeding body condition of fish species of different trophic guilds in the Paraná River floodplain, as well as the impacts of upstream impoundments on fish conditions. Attributes of the river floods (duration, time of year, intensity, and variability in a given year) and the body condition, measured by the mean residuals of length-weight ratios, of the detritivorous, herbivorous, insectivorous, invertivores, omnivorous, piscivorous, and planktivorous species were evaluated. Fish were sampled during a period before (1986-1994) and after (2000-2004) the completion of filling of the Porto Primavera Reservoir, which is located upstream from the floodplain area under study. Three sub-basins in the floodplain were sampled: the Ivinheima River, which has no dams; the Paraná River, which has several dams; and the Baia River, which is influenced by the Paraná. A two-way ANOVA identified significant variations in mean body conditions for localities and for the hydrological cycles, and the interactions were also significant. The findings revealed that before the Porto Primavera Reservoir was filled, the body condition of the feeding guilds varied similarly in the three sub basins, but this pattern was not observed after filling was completed. However, in years with minor or no floods, the body condition was high, especially in the sub-basins influenced by Porto Primavera (Paraná and Baía). Pearson's and Spearman's correlations showed that most effects of the floods were unfavorable to the body condition of the guilds, except for the annual variation in water level, which aids herbivores in accessing allochthonous food resources. Detritivores were negatively affected by all flood attributes. A correlation between the relative stomach weight (mean residual of the ratio of total and stomach weights) and the body condition demonstrated the poor relationship between the amount of food intake and

  8. Quantitative regularities in floodplain formation

    NASA Astrophysics Data System (ADS)

    Nevidimova, O.

    2009-04-01

    Quantitative regularities in floodplain formation Modern methods of the theory of complex systems allow to build mathematical models of complex systems where self-organizing processes are largely determined by nonlinear effects and feedback. However, there exist some factors that exert significant influence on the dynamics of geomorphosystems, but hardly can be adequately expressed in the language of mathematical models. Conceptual modeling allows us to overcome this difficulty. It is based on the methods of synergetic, which, together with the theory of dynamic systems and classical geomorphology, enable to display the dynamics of geomorphological systems. The most adequate for mathematical modeling of complex systems is the concept of model dynamics based on equilibrium. This concept is based on dynamic equilibrium, the tendency to which is observed in the evolution of all geomorphosystems. As an objective law, it is revealed in the evolution of fluvial relief in general, and in river channel processes in particular, demonstrating the ability of these systems to self-organization. Channel process is expressed in the formation of river reaches, rifts, meanders and floodplain. As floodplain is a periodically flooded surface during high waters, it naturally connects river channel with slopes, being one of boundary expressions of the water stream activity. Floodplain dynamics is inseparable from the channel dynamics. It is formed at simultaneous horizontal and vertical displacement of the river channel, that is at Y=Y(x, y), where х, y - horizontal and vertical coordinates, Y - floodplain height. When dу/dt=0 (for not lowering river channel), the river, being displaced in a horizontal plane, leaves behind a low surface, which flooding during high waters (total duration of flooding) changes from the maximum during the initial moment of time t0 to zero in the moment tn. In a similar manner changed is the total amount of accumulated material on the floodplain surface

  9. A geomorphic framework to assess changes to aquatic habitat due to flow regulation and channel and floodplain alteration of the Cedar River, Washington

    NASA Astrophysics Data System (ADS)

    Gendaszek, A. S.; Magirl, C. S.; Barnas, C. R.; Konrad, C. P.; Little, R.

    2010-12-01

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

  10. Dioxin-like toxicity in the Saginaw River Watershed: polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls in sediments and floodplain soils from the Saginaw and Shiawassee Rivers and Saginaw Bay, Michigan, USA.

    PubMed

    Kannan, Kurunthachalam; Yun, Se Hun; Ostaszewski, Arthur; McCabe, John M; Mackenzie-Taylor, Deborah; Taylor, Allan B

    2008-01-01

    Sediment and floodplain soils in the Saginaw River Watershed, Michigan, USA, have been demonstrated to be contaminated with a variety of organic compounds, including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). Existing data indicate that, at some locations, the contamination exceeds human health risk-based regulatory levels and ecological risk-based screening levels. In this study, concentrations of PCBs including non-ortho coplanar congeners, PCDDs, and PCDFs were measured in more than 120 sediment and floodplain soil samples collected from the Shiawassee River (a tributary of the Saginaw River), the Saginaw River, and Saginaw Bay, to determine the sources and magnitude of contamination, and to elucidate the contributions from individual contaminant groups to the overall 2,3,7,8-tetrachlorodibezo-p-dioxin equivalents (TEQs). Sediment and soil extracts were also analyzed for total dioxin-like activity by means of the H4IIE-luc cell bioassay. Elevated concentrations of PCBs (>1000 ng/g, dry weight) were found in surface sediment and floodplain soil samples collected from the Shiawassee River near Chase Lake, from Middleground Island in the Saginaw River, and from subsurface sediments in Saginaw Bay. Concentrations of PCDDs and PCDFs in sediment and floodplain soils from the Saginaw River and Saginaw Bay were 2 to 3 orders of magnitude higher than concentrations in the samples from the Shiawassee River. The highest PCDD/F concentration (55,200 pg/g, dry weight in a subsurface layer) was found in sediment collected at the mouth of the Saginaw River. Concentrations of PCDFs were greater than the concentrations of PCDDs in sediment from the Saginaw River. 2,3,7,8-TCDF, 1,2,3,7,8-PeCDF, and 2,3,4,7,8-PeCDF were the major PCDF congeners found in sediments from the Saginaw River. The elevated concentrations of PCDFs, and the predominance of the less highly chlorinated PCDF congeners, in sediments

  11. Thresholds in the response of free-floating plant abundance to variation in hydraulic connectivity, nutrients, and macrophyte abundance in a large floodplain river

    USGS Publications Warehouse

    Giblin, Shawn M.; Houser, Jeffrey N.; Sullivan, John F.; Langrehr, H.A.; Rogala, James T.; Campbell, Benjamin D.

    2014-01-01

    Duckweed and other free-floating plants (FFP) can form dense surface mats that affect ecosystem condition and processes, and can impair public use of aquatic resources. FFP obtain their nutrients from the water column, and the formation of dense FFP mats can be a consequence and indicator of river eutrophication. We conducted two complementary surveys of diverse aquatic areas of the Upper Mississippi River as an in situ approach for estimating thresholds in the response of FFP abundance to nutrient concentration and physical conditions in a large, floodplain river. Local regression analysis was used to estimate thresholds in the relations between FFP abundance and phosphorus (P) concentration (0.167 mg l−1L), nitrogen (N) concentration (0.808 mg l−1), water velocity (0.095 m s−1), and aquatic macrophyte abundance (65 % cover). FFP tissue concentrations suggested P limitation was more likely in spring, N limitation was more likely in late summer, and N limitation was most likely in backwaters with minimal hydraulic connection to the channel. The thresholds estimated here, along with observed patterns in nutrient limitation, provide river scientists and managers with criteria to consider when attempting to modify FFP abundance in off-channel areas of large river systems.

  12. Floodplain ecosystem processes

    NASA Astrophysics Data System (ADS)

    Melack, John M.; Novo, Evlyn M. L. M.; Forsberg, Bruce R.; Piedade, Maria T. F.; Maurice, Laurence

    Floodplains represent a major component of the central Amazon Basin and influence the hydrology, ecology, and biogeochemistry. Hess et al. (2003) used a classification of synthetic aperture radar data with 100 m resolution for a 1.77 million km2 quadrat in central Amazonia and identified 17% as wetland most of which was inundated a portion of each year. Total net production attributed to flooded forests (excluding wood increments), aquatic macrophytes, phytoplankton, and periphyton for the 1.77 million km2 quadrat was estimated to be about 300 Tg C a-1. Flooded forests accounted for 62% of the total, aquatic macrophytes accounted for 34%, and the remaining 4% was associated with periphyton and phytoplankton. Approximately 10% of the total is the amount of organic carbon exported annually by the Amazon River according to Richey et al. (1990), methane emission is about 2.5% according to Melack et al. (2004), and a similar percent is estimated to be buried in sediments. The remaining portion is close to being sufficient to fuel the respiration that results in the degassing of 210 ± 60 Tg C a-1 as carbon dioxide from the rivers and floodplains according to Richey et al. (2002). Variations in the distribution and inundation of floodplain habitats play a key role in the ecology and production of many commercially important freshwater fish. A significant relationship exists between maximum inundated area lagged by 5 years and annual yield of omnivores.

  13. Bacterioplankton features and its relations with doc characteristics and other limnological variables in Paraná river floodplain environments (PR/MS-Brazil)

    PubMed Central

    Teixeira, Mariana Carolina; Santana, Natália Fernanda; de Azevedo, Júlio César Rodrigues; Pagioro, Thomaz Aurélio

    2011-01-01

    Since the introduction of the Microbial Loop concept, many studies aimed to explain the role of bacterioplankton and dissolved organic carbon (DOC) in aquatic ecosystems. Paraná River floodplain system is a very complex environment where these subjects were little explored. The aim of this work was to characterize bacterial community in terms of density, biomass and biovolume in some water bodies of this floodplain and to verify its temporal variation and its relation with some limnological variables, including some indicators of DOC quality, obtained through Ultraviolet-visible (UV-VIS) and fluorescence spectroscopic analysis. Bacterial density, biomass and biovolume are similar to those from other freshwater environments and both density and biomass were higher in the period with less rain. The limnological and spectroscopic features that showed any relation with bacterioplankton were the concentrations of N-NH4 and P-PO4, water transparency, and some indicators of DOC quality and origin. The analysis of these relations showed a possible competition between bacterioplankton and phytoplankton for inorganic nutrients and that the DOC used by bacterioplankton is labile and probably from aquatic macrophytes. PMID:24031705

  14. Multiple Lines of Evidence Risk Assessment of Terrestrial Passerines Exposed to PCDFs and PCDDs in the Tittabawassee River Floodplain, Midland, Michigan, USA

    PubMed Central

    Fredricks, Timothy B.; Giesy, John P.; Coefield, Sarah J.; Seston, Rita M.; Tazelaar, Dustin L.; Roark, Shaun A.; Kay, Denise P.; Newsted, John L.; Zwiernik, Matthew J.

    2011-01-01

    A site-specific multiple lines of evidence risk assessment was conducted for house wrens (Troglodytes aedon) and eastern bluebirds (Sialia sialis) along the Tittabawassee River downstream of Midland, Michigan, where concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in flood-plain soils and sediments are greater compared to upstream areas and some of the greatest anywhere in the world. Lines of evidence supporting the population-level assessment endpoints included site-specific dietary- and tissue-based exposure assessments and population productivity measurements during breeding seasons 2005–2007. While a hazard assessment based on site-specific diets suggested that populations residing in the downstream floodplain had the potential to be affected, concentrations in eggs compared to appropriate toxicity reference values (TRVs) did not predict a potential for population-level effects. There were no significant effects on reproductive success of either species. The most probable cause of the apparent difference between the dietary- and tissue-based exposure assessments was that the dietary-based TRVs were overly conservative based on intraperitoneal injections in the ring-necked pheasant. Agreement between the risk assessment based on concentrations of PCDFs and PCDDs in eggs and reproductive performance in both species supports the conclusion of a small potential for population-level effects at this site. PMID:21804755

  15. An application of spatially constrained inversion using FD Helicopter EM data to characterise spatial variations in groundwater salinity across the floodplains of the Murray River in South-eastern Australia

    NASA Astrophysics Data System (ADS)

    Munday, T. J.; Viezzoli, A.; Fitzpatrick, A.

    2008-12-01

    The floodplains of the Murray River, situated in the southeast of Australia, have become extensively salinised, related in part to the discharge of naturally saline groundwater linked to increased recharge from land clearing and irrigation adjacent to the river. This problem has been compounded by extended drought conditions that prevail across the Murray Basin, resulting in increase in the accumulation and concentration of salt within the floodplain soils and an increase in salt loads to the river. Consequently in many floodplain areas along the Murray, the native riparian vegetation communities are in severe decline and Eucalyptus largiflorens (Black Box) and E. camaldulensis (Red Gum) communities are being significantly affected. A range management strategies are being employed to manage these issues, the manipulation of river flows to enhance biodiversity values (ie restore vegetation health) and the development of a hydro-dynamic models to better understand surface flows and the role of soils and elevation in floodplain vegetation health. Integral to these strategies is the acquisition of detailed spatial data on the distribution of salinity in floodplain soils and groundwater, thereby indicating patterns of groundwater evapotranspiration and baseflow across these areas. Hydrogeophysical data from electrical (inductive) methods have considerable potential to provide such data. We present an application of the Spatially Constrained Inversion (SCI) of RESOLVE FDHEM (airborne EM) data for defining spatial patterns of salinisation in the sunraysia irrigation area located in the lower Murray Basin of South Australia. Spatially Constrained Inversion uses Delaunay triangulation to set three dimensional constraints between neighbouring soundings, taking advantage of the spatial coherency that may be present in the data set. Conductivity information for individual soundings is linked through the spatial constraints, from well determined parameters to locally poorly

  16. The organic and mineral matter contents in deposits infilling floodplain basins: Holocene alluviation record from the Kłodnica and Osobłoga river valleys, southern Poland

    NASA Astrophysics Data System (ADS)

    Wójcicki, K. J.; Marynowski, L.

    2012-07-01

    The work examines the timing and environmental conditions of floodplain sedimentation in the valleys of the upland Kłodnica and piedmont Osobłoga rivers in the Upper Odra River basin. A distribution of 52 14C-ages shows relatively high floodplain sedimentation at the Late Glacial-Holocene transition, more stable floodplain environments since the Early (in the Kłodnica Valley) and Middle Holocene (in the Osobłoga Valley) and a gradual increase in floodplain deposition in the Late Holocene (since < 3.4 kyr BP). Organic matter [OM] and mineral matter [MM] fluctuations were correlated with variables responsible for the activation of erosion (i.e. vegetation changes, human impact and hydrological events) as well as factors affecting the local record of sedimentation (i.e. valley morphology, hydrologic conditions and episodes of local erosion). A clear relationship is shown between an increase in alluviation and climate- or human-induced extension of unforested areas. The deposition of mineral-rich sediments increases rapidly during periods characterized by non-arboreal pollen values exceeding approximately 8% in pollen diagrams. On the other hand, the results obtained do not confirm significant interactions between Holocene changes in forest composition and alluviation. Despite the settlement of agrarian groups, the sedimentary record of human activity in the Osobłoga catchment is very poor during the Neolithic and early Bronze Age. A large-scale alluviation of the Osobłoga and Kłodnica valleys was initiated during the settlement of people of the Lusatian culture from the middle Bronze Age and escalated in the early Middle Ages and Modern Times. The deposition of products of soil erosion was limited to between ca. 1.9-1.2 kyr BP, probably due to demographic regression during the Migration Period. Comparison of OM/MM fluctuations with phases of increased fluvial activity does not show a relationship between Holocene wetter phases and catchment sediment yield

  17. Paleolimnological assessment of riverine and atmospheric pathways and sources of metal deposition at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    PubMed

    MacDonald, Lauren A; Wiklund, Johan A; Elmes, Matthew C; Wolfe, Brent B; Hall, Roland I

    2016-02-15

    Growth of natural resource development in northern Canada has raised concerns about the effects on downstream aquatic ecosystems, but insufficient knowledge of pre-industrial baseline conditions continues to undermine ability of monitoring programs to distinguish industrial-derived contaminants from those supplied by natural processes. Here, we apply a novel paleolimnological approach to define pre-industrial baseline concentrations of 13 priority pollutant metals and vanadium and assess temporal changes, pathways and sources of these metals at a flood-prone lake (SD2) in the Slave River Delta (NWT, Canada) located ~500 km north of Alberta's oil sands development and ~140 km south of a former gold mine at Yellowknife, NWT. Results identify that metal concentrations, normalized to lithium concentration, are not elevated in sediments deposited during intervals of high flood influence or low flood influence since onset of oil sands development (post-1967) relative to the 1920-1967 baseline established at SD2. When compared to a previously defined baseline for the upstream Athabasca River, several metal-Li relations (Cd, Cr, Ni, Zn, V) in post-1967 sediments delivered by floodwaters appear to plot along a different trajectory, suggesting that the Peace and Slave River watersheds are important natural sources of metal deposition at the Slave River Delta. However, analysis revealed unusually high concentrations of As deposited during the 1950s, an interval of very low flood influence at SD2, which corresponded closely with emission history of the Giant Mine gold smelter indicating a legacy of far-field atmospheric pollution. Our study demonstrates the potential for paleolimnological characterization of baseline conditions and detection of pollution from multiple pathways in floodplain ecosystems, but that knowledge of paleohydrological conditions is essential for interpretation of contaminant profiles. PMID:26688053

  18. Paleolimnological assessment of riverine and atmospheric pathways and sources of metal deposition at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    PubMed

    MacDonald, Lauren A; Wiklund, Johan A; Elmes, Matthew C; Wolfe, Brent B; Hall, Roland I

    2016-02-15

    Growth of natural resource development in northern Canada has raised concerns about the effects on downstream aquatic ecosystems, but insufficient knowledge of pre-industrial baseline conditions continues to undermine ability of monitoring programs to distinguish industrial-derived contaminants from those supplied by natural processes. Here, we apply a novel paleolimnological approach to define pre-industrial baseline concentrations of 13 priority pollutant metals and vanadium and assess temporal changes, pathways and sources of these metals at a flood-prone lake (SD2) in the Slave River Delta (NWT, Canada) located ~500 km north of Alberta's oil sands development and ~140 km south of a former gold mine at Yellowknife, NWT. Results identify that metal concentrations, normalized to lithium concentration, are not elevated in sediments deposited during intervals of high flood influence or low flood influence since onset of oil sands development (post-1967) relative to the 1920-1967 baseline established at SD2. When compared to a previously defined baseline for the upstream Athabasca River, several metal-Li relations (Cd, Cr, Ni, Zn, V) in post-1967 sediments delivered by floodwaters appear to plot along a different trajectory, suggesting that the Peace and Slave River watersheds are important natural sources of metal deposition at the Slave River Delta. However, analysis revealed unusually high concentrations of As deposited during the 1950s, an interval of very low flood influence at SD2, which corresponded closely with emission history of the Giant Mine gold smelter indicating a legacy of far-field atmospheric pollution. Our study demonstrates the potential for paleolimnological characterization of baseline conditions and detection of pollution from multiple pathways in floodplain ecosystems, but that knowledge of paleohydrological conditions is essential for interpretation of contaminant profiles.

  19. Effects on tree swallows exposed to dioxin-like compounds associated with the Tittabawassee River and floodplain near Midland, Michigan, USA.

    PubMed

    Fredricks, Timothy B; Zwiernik, Matthew J; Seston, Rita M; Coefield, Sarah J; Tazelaar, Dustin L; Roark, Shaun A; Kay, Denise P; Newsted, John L; Giesy, John P

    2011-06-01

    Concentrations of dioxin-like compounds, primarily polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs), in soils and sediments downstream of Midland, Michigan (USA) were greater than upstream sites and prompted a site-specific hazard assessment of tree swallows breeding in the associated floodplains. Potential for adverse population-level effects from site-specific contaminant exposures were evaluated at study areas (SAs) along the Tittabawassee and Saginaw rivers downstream of Midland. The site-specific multiple lines of evidence approach to hazard assessment included endpoints for dietary- and tissue-based exposures, and population productivity measurements for tree swallows ([TS]; Tachycineta bicolor) measured during the 2005, 2006, and 2007 breeding seasons. Exposure to dioxin-like compounds in TS eggs were some of the greatest recorded and were similar among all upstream and downstream study sites. Conversely, concentrations in nestlings from SAs were significantly greater compared to reference areas (RAs). The pattern of relative concentrations of PCDD/DFs in eggs and nestlings at RAs was dominated by dioxin congeners, whereas at SAs it was dominated by furan congeners. No statistically significant differences were noted in exposure to PCDD/DFs or in population-level responses when compared among locations, and total clutch failures were rare. Hatching success and fledging success were weakly negatively correlated with concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) in individual eggs and nestlings, respectively. On-site concentrations of TEQs in floodplain soils were some of the greatest ever reported in the environment, and several lines of evidence indicate potential population-level effects on TS overall reproductive productivity.

  20. Quantitative regularities in floodplain formation

    NASA Astrophysics Data System (ADS)

    Nevidimova, O.

    2009-04-01

    Quantitative regularities in floodplain formation Modern methods of the theory of complex systems allow to build mathematical models of complex systems where self-organizing processes are largely determined by nonlinear effects and feedback. However, there exist some factors that exert significant influence on the dynamics of geomorphosystems, but hardly can be adequately expressed in the language of mathematical models. Conceptual modeling allows us to overcome this difficulty. It is based on the methods of synergetic, which, together with the theory of dynamic systems and classical geomorphology, enable to display the dynamics of geomorphological systems. The most adequate for mathematical modeling of complex systems is the concept of model dynamics based on equilibrium. This concept is based on dynamic equilibrium, the tendency to which is observed in the evolution of all geomorphosystems. As an objective law, it is revealed in the evolution of fluvial relief in general, and in river channel processes in particular, demonstrating the ability of these systems to self-organization. Channel process is expressed in the formation of river reaches, rifts, meanders and floodplain. As floodplain is a periodically flooded surface during high waters, it naturally connects river channel with slopes, being one of boundary expressions of the water stream activity. Floodplain dynamics is inseparable from the channel dynamics. It is formed at simultaneous horizontal and vertical displacement of the river channel, that is at Y=Y(x, y), where х, y - horizontal and vertical coordinates, Y - floodplain height. When dу/dt=0 (for not lowering river channel), the river, being displaced in a horizontal plane, leaves behind a low surface, which flooding during high waters (total duration of flooding) changes from the maximum during the initial moment of time t0 to zero in the moment tn. In a similar manner changed is the total amount of accumulated material on the floodplain surface

  1. A multidisciplinary approach to reveal floodplain palaeohydrography in the surrounding of ancient Luna archaeological site (lower Magra River valley, NW Italy)

    NASA Astrophysics Data System (ADS)

    Bini, Monica; Bisson, Marina; Chelli, Alessandro; Pappalardo, Marta

    2010-05-01

    The Magra floodplain (NW Italy) is a coastal plain that was created during the last 2.5 millennia by the River Magra itself and by minor streams draining the southern slope of the Apuan Alps. The coastline progressively migrated from the mountain foothills to its present position, 2.5 km seaward. Available stratigraphical data suggest that the marine gulf that occupied the area before Bronze age gradually changed into a lagoon; this was finally separated from the open sea and became a complex of marshes that were finally silted up. All these environments provided opportunities for settlement and land use: early settlement is accounted for in the Iron Age by Ligurian people that were finally defeated by the Romans. In the 2nd century bC the roman colony of Luna (today Luni) was founded in the area. After the Imperial Age Luni gradually decayed and was finally abandoned in 1204. Post-Roman alluviation is thought to be partly responsible for the city decline and the survival of only scattered farmsteads in its surroundings. Settlement and land use history from Iron Age onward are thus tightly dependant from drainage network evolution in the area. Although historical maps provide some chronological constraints about the advance of the Magra floodplain it is still unknown how and when precisely the transformation of a lagoon environment into a dry land occurred. In particular no data are available about the position of the mouths of the Magra River and of the minor streams at Roman Times and little is known about channel migration since the Early Middle Ages and information about land reclamation are difficult to find because dispersed. In order to identify abandoned fluvial channels, a series of digital elaborations were applied to different types of Remotely-Sensed Images. In detail, the used data consist of satellite images (Landsat 7 - ETM) and airborne orthophotos (AIMA) covering a temporal interval of five years (from 1998 to 2002) and characterized by a spatial

  2. Water quality of selected fluvial lakes in the context of the Elbe River pollution and anthropogenic activities in the floodplain.

    PubMed

    Chalupová, Dagmar; Havlíková, Petra; Janský, Bohumír

    2012-10-01

    The paper evaluates the status of selected fluvial lakes situated in the central part of the Elbe River and the impact of anthropogenic activities including comparison with the Elbe River water quality on them. To achieve the goals of the project, eight researched lakes differed from each other in the intensity of communication with the river, morphometric parameters and in the possibility of anthropogenic contamination (industrial, agricultural and municipal) were chosen. Besides observing the hydrological regime, the research was focused on physical and chemical parameters of water. To sum up, the lakes communicating above ground with the river showed similarities in several parameters, e.g. organic load or conductivity was nearly at the same level, which was lower than in the separated ones. Although the values of nitrates were higher in the river, their content did not reach such concentrations even in the connected lakes because of their more stagnant character. In general, although the Elbe River has a significant effect on water quality of researched lakes, especially in the case of lakes with a restricted communication with the river, their water quality is a result of local conditions, e.g. possibility of contamination by sewage waters, land use in the vicinity, etc.

  3. A Trans-disciplinary Hydrogeological Systems Analysis Approach for Identifying and Assessing Managed Aquifer Recharge Options: Example from the Darling River Floodplain, N.S.W., Australia

    NASA Astrophysics Data System (ADS)

    Lawrie, K.; Brodie, R. S.; Tan, K. P.; Halas, L.; Magee, J.; Gow, L.; Christensen, N. B.

    2013-12-01

    Surface water availability and quality generally limits managed aquifer recharge (MAR) opportunities in inland Australia's highly salinized landscapes and groundwater systems. Economic factors also commonly limit MAR investigations to shallow freshwater groundwater systems near existing infrastructure. Aquifer opportunities lie mainly in zones of fresh groundwater in relatively thin fluvial sedimentary aquifer systems with highly variable hydraulic properties. As part of a broader strategy to identify water savings in the Murray-Darling Basin, the Broken Hill Managed Aquifer Recharge (BHMAR) project was tasked with identifying and assessing MAR and/or groundwater extraction options to reduce evaporative losses from existing surface water storages, secure Broken Hill's water supply, protect the local environment and heritage, and return water to the river system. A trans-disciplinary research approach was used to identify and assess MAR options across a broad area of the Darling River floodplain. This methodology enabled the team to recognise fundamental problems in discipline approaches, helped identify critical data gaps, led to significant innovation across discipline boundaries, was critical in the development of a new hydrogeological conceptual model, facilitated development of new models of landscape, geological and tectonic evolution of the study area, and enabled completion of pre-commissioning maximal and residual MAR risk assessments. An airborne electromagnetics (AEM) survey, acquired over a large (>7,500 sq km) area of the Darling Floodplain, enabled rapid identification of a multi-layer sequence of aquifers and aquitards, while a phased assessment methodology was developed to rapidly identify and assess over 30 potential MAR targets (largely in fresh groundwater zones within palaeochannels and at palaeochannel confluences). Hydraulic properties were confirmed by a 7.5 km drilling program (100 sonic and rotary mud holes), and complementary field

  4. Numerical simulation of bar and bank erosion in a vegetated floodplain: A case study in the Otofuke River

    NASA Astrophysics Data System (ADS)

    Iwasaki, Toshiki; Shimizu, Yasuyuki; Kimura, Ichiro

    2016-07-01

    Recent studies suggest that braided river could be single-thread channel by colonization of riparian vegetation; however, this kind of mutual interactions between physical and ecological processes in rivers are still poorly understood. Here we investigate the development of meandering channel in a river, which was originally braided and currently vegetated, the Otofuke River in Japan. The significant morphological processes of this river during a destructive flood event was studied using a two-dimensional morphodynamic model. Using well-calibrated parameters, this model qualitatively reproduced observed morphological changes such as the co-development of sand bars, bar-induced meandering and a chute cutoff. We find that for vegetated channels, meandering could maintain moderate sinuosity; in contrast, in the absence of riparian vegetation, bar-induced meandering channels could become braided. This suggests that distinct meandering channels could be a fundamental channel morphology in the originally braided, but currently vegetated river; however, the simultaneous occurrence of the chute cutoff and meandering indicates that this channel could not be a fully-developed high amplitude meandering channel.

  5. Cosmogenic nuclide budgeting of floodplain sediment transfer

    NASA Astrophysics Data System (ADS)

    Wittmann, H.; von Blanckenburg, F.

    2009-08-01

    Cosmogenic nuclides produced in quartz may either decay or accumulate while sediment is moved through a river basin. A change in nuclide concentration resulting from storage in a floodplain is potentially important in large drainage basins in which sediment is prone to repeated burial and remobilization as a river migrates through its floodplain. We have modeled depth- and time-dependent cosmogenic nuclide concentration changes for 10Be, 26Al, and 14C during sediment storage and mixing in various active floodplain settings ranging from confined, shallow rivers with small floodplains to foreland-basin scale floodplains traversed by deep rivers. Floodplain storage time, estimated from channel migration rates, ranges from 0.4 kyr for the Beni River basin (Bolivia) to 7 kyr for the Amazon River basin, while floodplain storage depth, estimated from channel depth, ranges from 1 to 25 m. For all modeled active floodplain settings, the long-lived nuclides 10Be and 26Al show neither significant increase in nuclide concentration from irradiation nor decrease from decay. We predict a hypothetical response time after which changes in 10Be or 26Al concentrations become analytically resolvable. This interval ranges from 0.07 to 2 Myr and exceeds in all cases the typical residence time of sediment in a floodplain. Due to the much shorter half life of 14C, nuclide concentrations modeled for the in situ-produced variety of this nuclide are, however, sensitive to floodplain storage on residence times of < 20 kyr. The cosmogenic nuclide composition of old deposits in currently inactive floodplains that have been isolated for periods of millions of years from the river that once deposited them is predicted to either increase or decrease in 10Be and 26Al concentration, depending on the depositional depth. These conditions can be evaluated using the 26Al/ 10Be ratio that readily discloses the depth and duration of storage. We illustrate these models with examples from the Amazon basin

  6. Control of reed canarygrass promotes wetland herb and tree seedling establishment in an upper Mississippi River Floodplain forest

    USGS Publications Warehouse

    Thomsen, Meredith; Brownell, Kurt; Groshek, Matthew; Kirsch, Eileen

    2012-01-01

    Phalaris arundinacea (reed canarygrass) is recognized as a problematic invader of North American marshes, decreasing biodiversity and persisting in the face of control efforts. Less is known about its ecology or management in forested wetlands, providing an opportunity to apply information about factors critical to an invader's control in one wetland type to another. In a potted plant experiment and in the field, we documented strong competitive effects of reed canarygrass on the establishment and early growth of tree seedlings. In the field, we demonstrated the effectiveness of a novel restoration strategy, combining site scarification with late fall applications of pre-emergent herbicides. Treatments delayed reed canarygrass emergence the following spring, creating a window of opportunity for the early growth of native plants in the absence of competition from the grass. They also allowed for follow-up herbicide treatments during the growing season. We documented greater establishment of wetland herbs and tree seedlings in treated areas. Data from small exclosures suggest, however, that deer browsing can limit tree seedling height growth in floodplain restorations. Slower tree growth will delay canopy closure, potentially allowing reed canarygrass re-invasion. Thus, it may be necessary to protect tree seedlings from herbivory to assure forest regeneration.

  7. Geomorphic response to flow regulation and channel and floodplain alteration in the gravel-bedded Cedar River, Washington, USA

    USGS Publications Warehouse

    Gendaszek, Andrew S.; Magirl, Christopher S.; Czuba, Christiana R.

    2012-01-01

    Decadal- to annual-scale analyses of changes to the fluvial form and processes of the Cedar River in Washington State, USA, reveal the effects of flow regulation, bank stabilization, and log-jam removal on a gravel-bedded river in a temperate climate. During the twentieth century, revetments were built along ~ 60% of the lower Cedar River's length and the 2-year return period flow decreased by 47% following flow regulation beginning in 1914. The formerly wide, anastomosing channel narrowed by over 50% from an average of 47 m in 1936 to 23 m in 1989 and became progressively single threaded. Subsequent high flows and localized revetment removal contributed to an increase in mean channel width to about 34 m by 2011. Channel migration rates between 1936 and 2011 were up to 8 m/year in reaches not confined by revetments or valley walls and less than analysis uncertainty throughout most of the Cedar River's length where bank armoring restricted channel movement. In unconfined reaches where large wood and sediment can be recruited, contemporary high flows, though smaller in magnitude than preregulation high flows, form and maintain geomorphic features such as pools, gravel bars, and side channels. Reaches confined by revetments remain mostly unmodified in the regulated flow regime. While high flows are important for maintaining channel dynamics in the Cedar River, their effectiveness is currently reduced by revetments, limited sediment supply, the lack of large wood available for recruitment to the channel, and decreased magnitude since flow regulation.

  8. Hydrologic effects on diameter growth phenology for Celtis laevigata and Quercus lyrata in the floodplain of the lower White River, Arkansas

    USGS Publications Warehouse

    Allen, Scott T; Cochran, Wesley; Krauss, Ken W.; Keim, Richard F.; King, Sammy L.; Schweitzer, Callie Jo; Clatterbuck, Wayne K.; Oswalt, Christopher M.

    2016-01-01

    Bottomland hardwood (BLH) forests represent an extensive wetland system in the Mississippi Alluvial Valley and southeastern USA, and it is currently undergoing widespread transition in species composition. One such transition involves increased establishment of sugarberry (Celtis laevigata), and decreased establishment of overcup oak (Quercus lyrata). The ecological mechanisms that control this transition are not well understood. We measured monthly diameter growth with dendrometer bands on 86 sugarberry and 42 overcup oak trees at eight sites in the floodplain of the White River (AR, USA) with differing hydrologic regimes. For both species, growth attenuated earlier at drier sites compared to wetter sites. Overcup oak grew slightly longer through late August, suggesting its growth period extends across both wet and dry periods. In contrast, sugarberry growth rate decreased substantially by mid-July. While these results did not necessarily indicate a mechanism for increased prominence of sugarberry, they suggest sugarberry growing season does not as much coincide with the typically drier period of late summer and may be less affected by these conditions. Overcup oak grows later into the dry season and water table conditions during this period may determine if overcup oak benefits from this relatively extended growth period.

  9. Biodiversity of testate amoebae (Arcellinida and Euglyphida) in different habitats of a lake in the Upper Paraná River floodplain.

    PubMed

    Alves, Geziele Mucio; Velho, Luiz Felipe Machado; Simões, Nadson Ressyé; Lansac-Tôha, Fábio Amodêo

    2010-11-01

    This study aimed to investigate the testate amoebae (Arcellinida and Eugliphida) species diversity in plankton, macrophytes and aquatic sediment samples from a shallow lake of the Upper Paraná River floodplain. Samples were carried out from April 2007 to March 2008. We recorded 89 taxa, belonging to 10 families. Eighty-two taxa were found in the aquatic sediment, 71 in the macrophytes and 53 in the plankton. Highest values of alpha diversity were observed in the aquatic sediment. Although the plankton had the highest number of accidental species, accessory and constant species were also observed in this habitat. Most of the species classified as constant for the plankton belonged to the genus Arcella. Most of the constant species in the macrophytes and aquatic sediment belonged to the genus Difflugia. This study supports the idea that the presence of these protists in the plankton should not be attributed only to stochastic processes because (i) the species diversity recorded in this habitat was remarkably high in relation to the total biodiversity of the lake, and (ii) we also recorded frequent and constant species in the plankton.

  10. Ecological risk assessment of great horned owls (Bubo virginianus) exposed to PCDD/DF in the Tittabawassee River floodplain in Midland, Michigan, USA.

    PubMed

    Coefield, Sarah J; Fredricks, Timothy B; Seston, Rita M; Nadeau, Michael W; Tazelaar, Dustin L; Kay, Denise P; Newsted, John; Giesy, John P; Zwiernik, Matthew J

    2010-10-01

    Soils and sediments downstream of Midland, Michigan, USA have elevated polychlorinated dibenzofuran (PCDF) and polychlorinated dibenzo-p-dioxin (PCDD) concentrations. To determine if the PCDD/DF concentrations have the potential to adversely affect terrestrial avian predators, a site-specific, multiple lines of evidence risk assessment was conducted for the great horned owl (Bubo virginianus; GHO). As long-lived resident top predators, the GHO has the potential to be exposed to relatively great concentrations of bioaccumulative compounds such as PCDD/DF. From 2005 to 2008, concentrations of PCDD/DF were measured in blood plasma of adult and nestling GHOs and addled eggs. Indicators of the condition of the population, including abundance and reproductive success, were collected along 115 km of river corridor. Fifty-five active 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) equivalents (TEQ(WHO-Avian)) nests were monitored in 21 breeding territories from 2005 to 2008. The geometric mean concentration in blood plasma of GHOs was greater in the study area (SA) than in the reference area (RA) for both adults (RA: 3.1; SA: 9.4 ng TEQ(WHO-Avian)/kg) and nestlings (RA: 0.82 ng TEQ(WHO-Avian)/kg, SA: 2.1 ng TEQ(WHO-Avian)/kg) GHOs, but less than concentrations expected to cause adverse effects based on laboratory studies. Concentrations of TEQ(WHO-Avian) in addled GHO eggs were also greater in the SA than the RA (50 and 7.3 ng/kg, wet weight, respectively), but were less than concentrations expected to cause adverse effects. The GHO population condition and productivity were both greater in the study area than in the reference area and were similar to other GHO populations. This result suggests the GHO population in the Tittabawassee River floodplain is consistent with what would be expected for this area. PMID:20872699

  11. Changes of floodplain morphology by water mills: Legacy sediments stored behind mill dams as archive and source for pollution - Examples from the Wurm River, Lower Rhine Embayment, Germany

    NASA Astrophysics Data System (ADS)

    Buchty-Lemke, Michael; Frings, Roy; Hagemann, Lukas; Lehmkuhl, Frank; Maaß, Anna-Lisa; Schwarzbauer, Jan

    2016-04-01

    The Wurm River (Lower Rhine Embayment, Germany) is a small stream in a low mountain area near the Dutch-German border that has seen a lot of anthropogenic changes of its morphology since medieval times. Among other influencing factors, water mills, in particular, had an early impact on the sediment dynamics and created sediment traps. Several knickpoints in the long profile may represent the legacy of mill damming - or founded mill building at these spots. The knickpoints may also represent the aftermath of the colliery history. A study site in the upper reaches of the Wurm River features erosion terraces, incised following the demise of a mill dam in the early 20th century. The mill pond most likely collected sediment and additives e.g. used in agricultural and industrial processes. These legacy sediments from behind former mill dams provide information about anthropogenic pollution, particularly for the era of industrialization in the vicinity of the old industrial area of the city of Aachen. Along with the demise of the mill dam and the increased incision tendency, the sediments are also a secondary source for pollution in case of remobilization of contaminated sediments. Two major research questions are addressed. A) Which individual hydrological and geomorphological processes, both upstream and downstream, triggered the incision and the construction of the erosion terraces, which are preserved in the mill pond sediments? Is either the demised mill dam, or subsidence effects, or a combination of both the determining factor? B) Which contaminants are retained in the sediments? Is there a detectable point source for the pollutants or is it a mixture of diffuse anthropogenic (industry, agriculture, traffic, wastewater) and natural origin? To tackle these questions, sedimentological data are combined with geomorphological mapping and evaluation of historical data. A soil profile provides insight into the architecture of the floodplain, which is built of riverbed

  12. Projecting avian response to linked changes in groundwater and riparian floodplain vegetation along a dryland river: a scenario analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Groundwater is a key driver of riparian condition on dryland rivers but is in high demand for municipal, industrial, and agricultural uses. Approaches are needed to guide decisions that balance human water needs while conserving riparian ecosystems. We developed a space-for-time substitution model ...

  13. RVR Meander – Migration of meandering rivers in homogeneous and heterogeneous floodplains using physically-based bank erosion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The RVR Meander platform for computing long-term meandering-channel migration is presented, together with a method for planform migration based on the modeling of the streambank erosion processes of hydraulic erosion and mass failure. An application to a real-world river, with assumption of homogene...

  14. Restoring the Mississippi River Basin from the Catchment to the Coast Defines Science and Policy Issues of Ecosystem Services Associated with Alluvial and Coastal Deltaic Floodplains: Soil Conservation, Nutrient Reduction, Carbon Sequestration, and Flood Control

    NASA Astrophysics Data System (ADS)

    Twilley, R.

    2014-12-01

    Large river systems are major economic engines that provide national economic wealth in transporting commerce and providing extensive agriculture production, and their coastal deltas are sites of significant ports, energy resources and fisheries. These coupled natural and social systems from the catchment to the coast depend on how national policies manage the river basins that they depend. The fundamental principle of the Mississippi River Basin, as in all basins, is to capitalize on the ability of fertile soil that moves from erosional regions of a large watershed, through downstream regions of the catchment where sediment transport and storage builds extensive floodplains, to the coastal region of deposition where deltas capture sediment and nutrients before exported to the oceans. The fate of soil, and the ability of that soil to do work, supports the goods and services along its path from the catchment to the coast in all large river basin and delta systems. Sediment is the commodity of all large river basin systems that together with the seasonal pulse of floods across the interior of continents provide access to the sea forming the assets that civilization and economic engines have tapped to build national and global wealth. Coastal landscapes represent some of the most altered ecosystems worldwide and often integrate the effects of processes over their entire catchment, requiring systemic solutions to achieve restoration goals from alluvial floodplains upstream to coastal deltaic floodplains downstream. The urgent need for wetland rehabilitation at landscape scales has been initiated through major floodplain reclamation and hydrologic diversions to reconnect the river with wetland processes. But the constraints of sediment delivery and nutrient enrichment represent some critical conflicts in earth surface processes that limit the ability to design 'self sustaining' public work projects; particularly with the challenges of accelerated sea level rise. Only

  15. Human-induced stream channel abandonment/capture and filling of floodplain channels within the Atchafalaya River Basin, Louisiana

    USGS Publications Warehouse

    Kroes, Daniel E.; Kraemer, Thomas F.

    2013-01-01

    The Atchafalaya River Basin is a distributary system of the Mississippi River containing the largest riparian area in the lower Mississippi River Valley and the largest remaining forested bottomland in North America. Reductions in the area of open water in the Atchafalaya have been occurring over the last 100 years, and many historical waterways are increasingly filled by sediment. This study examines two cases of swamp channels (3/s) that are filling and becoming unnavigable as a result of high sediment loads and slow water velocities. The water velocities in natural bayous are further reduced because of flow capture by channels constructed for access. Bathymetry, flow, suspended sediment, deposited bottom-material, isotopes, and photointerpretation were used to characterize the channel fill. On average, water flowing through these two channels lost 23% of the suspended sediment load in the studied reaches. Along one of the studied reaches, two constructed access channels diverted significant flow out of the primary channel and into the adjacent swamp. Immediately downstream of each of the two access channels, the cross-sectional area of the studied channel was reduced. Isotopic analyses of bottom-material cores indicate that bed filling has been rapid and occurred after detectable levels of Cesium-137 were no longer being deposited. Interpretation of aerial photography indicates that water is bypassing the primary channels in favor of the more hydraulically efficient access channels, resulting in low or no-velocity flow conditions in the primary channel. These swamp channel conditions are typical in the Atchafalaya River Basin where relict large channel dimensions result in flow velocities that are normally too low to carry fine-grained sediment. Constructed channels increase the rate of natural channel avulsion and abandonment as a result of flow capture.

  16. Basin-wide sediment interactions between channels, floodplains and dunes in a large, dryland river system, central Australia

    NASA Astrophysics Data System (ADS)

    Eccleshall, Sarah; Jansen, John; Fujioka, Toshiyuki; Codilean, Alexandru; Mifsud, Charles

    2015-04-01

    Low, flat terrain (slope 400 kyr) implied in the 'storage' hypothesis. The 26Al/10Be ratio has been used to identify a complex exposure history, such as one including burial, where a lower offset in 26Al/10Be ratio from the expected production-rate ratio of 6.8 can be converted to a burial age. Eleven detrital samples were collected along the full length of the Cooper, plus three surface samples from source-bordering dunes in the lowermost reach. We discuss our preliminary findings with regard to sediment burial and long-term interactions in the river-dune systems of central Australia. References: 1Willenbring, J. K., Codilean, A. T., Ferrier, K. L., McElroy, B., & Kirchner, J. W. (2014). Short Communication: Earth is (mostly) flat, but mountains dominate global denudation: apportionment of the continental mass flux over millennial time scales, revisited. Earth Surface Dynamics Discussions, 2(1), 1-17. 2Magee, J. W., Miller, G. H., Spooner, N. A., & Questiaux, D. (2004). Continuous 150 ky monsoon record from Lake Eyre, Australia: insolation-forcing implications and unexpected Holocene failure. Geology, 32(10), 885-888. 3Jansen, J. D., Nanson, G. C., Cohen, T. J., Fujioka, T., Fabel, D., Larsen, J. R., Codilean, A. T., Price, D.M, Bowman, H. H., May, J-H. & Gliganic, L. A. (2013). Lowland river responses to intraplate tectonism and climate forcing quantified with luminescence and cosmogenic 10Be. Earth and Planetary Science Letters, 366, 49-58.

  17. Molecular characterization of the endophytic fungal community associated with Eichhornia azurea (Kunth) and Eichhornia crassipes (Mart.) (Pontederiaceae) native to the Upper Paraná River floodplain, Brazil.

    PubMed

    Almeida, T T; Orlandelli, R C; Azevedo, J L; Pamphile, J A

    2015-05-11

    Endophytic fungi live in the interior of healthy plants without causing them any damage. These fungi are of biotechnological interest; they may be used in the biological control of pests and plant diseases, and in the pharmaceutical industry. The aquatic macrophytes Eichhornia azurea (Kunth) and Eichhornia crassipes (Mart.) belong to the Pontederiaceae family. The first is a fixed-floating species and the second is a free-floating species that is known for its phytoremediation potential. The fungal endophytes associated with the leaves of E. azurea and E. crassipes, native to the Upper Paraná River floodplain, Brazil, were isolated. The sequencing of the ITS1-5.8S-ITS2 region of ribosomal DNA was performed and the nucleotide sequences obtained were compared with those available in the GenBank database for the molecular identification of the isolates. The construction of phylogenetic trees was performed using the MEGA5 software. The results showed that high colonization frequencies were obtained from the 610 foliar fragments sampled from each plant: 87.86% for E. azurea and 88.85% for E. crassipes. At the genus level, it was possible to identify 19 fungal endophytes belonging to the genera Alternaria, Bipolaris, Cercospora, Diaporthe, Gibberella, Pestalotiopsis, Plectosphaerella, Phoma, and Saccharicola. Two other endophytes were identified at the species level (Microsphaeropsis arundinis). Genera Bipolaris, Cercospora, Microsphaeropsis, and Phoma were found as endophytes in the two macrophytes and the other genera were host-specific, being isolated from only one macrophyte, proving that there is a small difference in the endophytic diversity of the two Eichhornia species analyzed.

  18. A coupled hydrodynamic and breach formation model to simulate floodplain inundations: the case study of the Bacchiglione River (Italy)

    NASA Astrophysics Data System (ADS)

    Viero, D.; D'Alpaos, A.; Carniello, L.; Defina, A.; Genevois, R.

    2011-12-01

    We present a numerical hydrodynamic model which couples a previously described model solving the two-dimensional shallow water equations modified in order to deal with partially wet and very irregular domains with a conceptual model simulating the process of breach formation and development in fluvial levees. The coupled model allows us to simulate flood propagation over unchanneled areas adjacent to the river segment thus providing a quantitative estimate of the consequent inundations of such areas. The two dimensional depth integrated momentum and continuity equations are modified to take into account the bottom irregularities that strongly affect the hydrodynamics in partially dry areas, as for example, in the first stages of an inundation process. The breach formation module allows one to simulate the formation of failures either by piping or by overtopping of existing levees. Because in general a river has a limited inner capacity with respect to reservoirs, the coupling of the above models makes it possible to account for the highly variable hydraulic conditions, both in space and time, which occur close to the breach. This is deemed to be a necessary feature of this type of models because the evolution of the breach itself, and therefore the extension of the flooded areas, strongly depend on the altered driving hydrodynamic conditions which characterize the flow field both within the channel and over the adjacent areas. The model therefore provides a better description of the process of breach formation compared to classical models which assume static driving hydraulic conditions in proximity of the breach. Moreover, the use of a conceptual model for breach formation, either by piping or by overtopping, reduces the computational effort therefore allowing for the extensive application of the coupled model to actual case studies. We have applied the model to a case study in which the effects of breach formation across the Bacchiglione River (North

  19. Selecting reconnaissance strategies for floodplain surveys

    NASA Technical Reports Server (NTRS)

    Sollers, S. C.; Rango, A.; Henninger, D. L.

    1977-01-01

    Multispectral aircraft and satellite data over the West Branch of the Susquehanna River were analyzed to evaluate potential contributions of remote sensing to flood-plain surveys. Multispectral digital classifications of land cover features indicative of floodplain areas were used by interpreters to locate various floodprone area boundaries. The digital approach permitted LANDSAT results to be displayed at 1:24,000 scale and aircraft results at even larger scales. Results indicate that remote sensing techniques can delineate floodprone areas more easily in agricultural and limited development areas as opposed to areas covered by a heavy forest canopy. At this time it appears that the remote sensing data would be best used as a form of preliminary planning information or as an internal check on previous or ongoing floodplain studies. In addition, the remote sensing techniques can assist in effectively monitoring floodplain activities after a community enters into the National Flood Insurance Program.

  20. Patterns of food resource use by two congeneric species of piranhas (Serrasalmus) on the Upper Paraná River floodplain.

    PubMed

    Agostinho, C S; Hahn, N S; Marques, E E

    2003-05-01

    Serrasalmus marginatus invaded the Upper Paraná River after construction of the Itaipu Dam in November 1982. This was followed by a reduction in abundance of the native species S. spilopleura. Analysis of the pattern of food resource use revealed that both species employ the same feeding strategy, eating mainly fish (whole fish or muscle fragments) and fins bitten off their prey. The diurnal activity period and the feeding rhythm were better-defined in S. marginatus. For young individuals of both species, food was taken in a significantly discontinuous manner (F = 2.83; p < 0.05 and F = 13.25; p < 0.05), with a peak at 4 p.m. Ontogenetic differences in diet, the strong feeding overlap of larger individuals of S. marginatus and smaller individuals of S. spilopleura, and the aggressiveness of S. marginatus in establishing feeding territories may have contributed to the success of the invading species.

  1. Ecology of endoparasites of the fluvial stingray Potamotrygon falkneri (Chondrichthyes: Potamotrygonidae) from the upper Paraná River floodplain, Brazil.

    PubMed

    Lacerda, A C F; Takemoto, R M; Pavanelli, G C

    2009-05-01

    The present study investigated the ecological relationships between endoparasites and the host Potamotrygon falkneri from the upper Paraná River by using as indicators the host's relative condition factor (Kn), sex and hepatosomatic relation (HSR). Forty-seven specimens of P. falkneri were analyzed between March 2005 and September 2006. Statistical analysis showed that the Kn was positively correlated with the abundance of Acanthobothrium regoi and Rhinebothrium paratrygoni; only the abundance of A. regoi was positively correlated to the HSR, whereas R. paratrygoni did not present correlation and there was no influence of the host's sex on the abundance and prevalence of parasites. This is the first study concerning the ecology of parasites of potamotrygonids. PMID:19675930

  2. Effects of spatial and temporal variation in metal availability on earthworms in floodplain soils of the river Dommel, The Netherlands.

    PubMed

    Bleeker, Eric A J; van Gestel, Cornelis A M

    2007-08-01

    Regarding impact on ecological soil functioning, metal pollution is often considered a constant factor for certain sampling sites. However, especially bioavailable concentrations may differ in space and time. This aspect was investigated on four sites along a metal-polluted river, differing in soil characteristics and metal concentrations. Every four weeks earthworm densities, soil characteristics, and metal concentrations in soil and earthworms were determined. Earthworm biomass and density fluctuated in time and increased with increasing metal contamination, indicating the presence of compensating factors. Multivariate analysis suggested organic matter and moisture content to be the main factors explaining earthworm biomass. Metal concentrations in the earthworms increased with increasing total or 0.01M CaCl(2) extractable soil concentrations, but no time-related trends were seen. Cadmium concentrations in the earthworms exceeded background values, suggesting a potential risk. The neutral red retention biomarker assay, however, did not show any signs of metal stress in the earthworms. PMID:17376569

  3. Characterizing baseline concentrations, proportions, and processes controlling deposition of river-transported bitumen-associated polycyclic aromatic compounds at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    PubMed

    Elmes, Matthew C; Wiklund, Johan A; Van Opstal, Stacey R; Wolfe, Brent B; Hall, Roland I

    2016-05-01

    Inadequate knowledge of baseline conditions challenges ability for monitoring programs to detect pollution in rivers, especially where there are natural sources of contaminants. Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition. Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters. Lower concentrations at SD2 are likely a consequence of sediment retention upstream as well as dilution by sediment influx from the Peace River. In addition, relations with organic matter content reveal that flood events dilute concentrations of indicator PACs in SD2 because the lake receives high-energy floods and the lake sediments are predominantly inorganic. This contrasts with PAD31 where floodwaters increase indicator PAC concentrations in the lake sediments, and concentrations are diluted during low flood influence intervals due to increased deposition of lacustrine organic matter. Results also show no significant differences in concentrations and proportions of indicator PACs between pre- (1967) and post- (1980s and 1990 s) oil sands development high flood influence intervals (t = 1.188, P = 0.279, d.f. = 6.136), signifying that they are delivered to the SRD by natural processes. Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts. PMID:27071660

  4. Characterizing baseline concentrations, proportions, and processes controlling deposition of river-transported bitumen-associated polycyclic aromatic compounds at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    PubMed

    Elmes, Matthew C; Wiklund, Johan A; Van Opstal, Stacey R; Wolfe, Brent B; Hall, Roland I

    2016-05-01

    Inadequate knowledge of baseline conditions challenges ability for monitoring programs to detect pollution in rivers, especially where there are natural sources of contaminants. Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition. Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters. Lower concentrations at SD2 are likely a consequence of sediment retention upstream as well as dilution by sediment influx from the Peace River. In addition, relations with organic matter content reveal that flood events dilute concentrations of indicator PACs in SD2 because the lake receives high-energy floods and the lake sediments are predominantly inorganic. This contrasts with PAD31 where floodwaters increase indicator PAC concentrations in the lake sediments, and concentrations are diluted during low flood influence intervals due to increased deposition of lacustrine organic matter. Results also show no significant differences in concentrations and proportions of indicator PACs between pre- (1967) and post- (1980s and 1990 s) oil sands development high flood influence intervals (t = 1.188, P = 0.279, d.f. = 6.136), signifying that they are delivered to the SRD by natural processes. Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts.

  5. Effects of flooding regime on the feeding activity and body condition of piscivorous fish in the Upper Paraná River floodplain.

    PubMed

    Luz-Agostinho, K D G; Agostinho, A A; Gomes, L C; Júlio, H F; Fugi, R

    2009-06-01

    Flood pulses affect floodplain enrichment via the incorporation of nutrients and terrestrial biomass. As a result, they positively affect the body condition of aquatic organisms. This paper evaluates whether the absence of floods (resulting from dam control) affects the feeding activity and body condition of piscivorous fish. In addition, whether piscivores respond similarly to alterations in the flooding regime was assessed. Five piscivorous species were selected (Acestrorhynchus lacustris, Hoplias aff. malabaricus, Plagioscion squamosissimus, Rhaphiodon vulpinus, and Salminus brasiliensis). The fish were captured in four distinct years and in three river subsystems with differentiated water level fluctuations (Ivinheira = not regulated; Baía = regulated by the Paraná River level; Paraná = regulated by dams). Feeding activity and body condition were evaluated using the mean values of the standard residuals generated by regression models between body and stomach weights and standard length and body weight (all log-transformed). Differences among years and subsystems were evaluated via two-way analysis of variance. Pearson and Spearman correlations were performed between flooding attributes (duration, amplitude, timing, and daily variability) and feeding activity and body condition. Feeding activity differed across subsystems, whereas body condition varied across years, depending on the subsystem. Hoplias aff malabaricus (an ambusher adapted to starvation) presented feeding activity independent of the flooding regime and also presented better body condition in times of high water levels. Rhaphidon vulpinus exhibited variations in feeding activity but did not present alterations in body condition. The other species presented poorer body condition in years or subsystems with regular floods. Correlations identified that the duration and timing of floods had negative effects on body condition, whereas amplitude and mean annual water level improved feeding activity

  6. Human occupation along the Steel Creek floodplain: results of an intensive archeological survey for the L area reactivation project, Savannah River Plant, Barnwell County, South Carolina. Research manuscript series 173

    SciTech Connect

    Hanson, G.T. Jr.; Brooks, R.D.; White, J.W.

    1981-12-01

    An intensive archeological survey of the Steel Creek terrace and floodplain system below the L Reactor Area was conducted for the purpose of identifying the archeological resources and assessing their significance within this portion of the Savannah River Plant. The survey was required as part of the project plan for the reactivation of the L Reactor in order to comply with the requirements of the National Environmental Policy Act of 1969, Executive Order 11593, the National Historic Preservation Act of 1966, as amended in 1980, and the Archeological and Historic Preservation of 1974. In accordance with these laws, a complete archeological survey of the potential impact area along Steel Creek was accomplished, resulting in the recovery of data for 18 archeological sites. According to the evidence recovered from the 18 sites, the Steel Creek watershed's occupation extends to at least 8000 B.P. Site 38BR55 is considered eligible for nomination to the National Register of Historic Places. Recommendations for the protection of this site and of four historic earthen structures in the floodplain are presented, along with a summary of the archeological background, methods, environmental reconstruction, research results, and recommendations resulting from the survey of the Steel Creek terrace and floodplain system.

  7. Evidence of floods on the Potomac River from anatomical abnormalities in the wood of flood-plain trees

    USGS Publications Warehouse

    Yanosky, Thomas M.

    1983-01-01

    Ash trees along the Potomac River flood plain near Washington, D.C., were studied to determine changes in wood anatomy related to flood damage, and anomalous growth was compared to flood records for April 15 to August 31, 1930-79. Collectively, anatomical evidence was detected for 33 of the 34 growing-season floods during the study period. Evidence of 12 floods prior to 1930 was also noted, including catastrophic ones in 1889 and 1924. Trees damaged after the transition from earlywood to latewood growth typically formed ' flood rings ' of enlarged vessels within the latewood zone. Trees damaged near the beginning of the growth year developed flood rings within, or contiguous with, the earlywood. Both patterns are assumed to have developed when flood-damaged trees produced a second crop of leaves. Trees damaged by high-magnitude floods developed well formed flood rings along the entire height and around the entire circumference of the stem. Small floods were generally associated wtih diffuse or discontinuous anomalies restricted to stem apices. Frequency of flood rings was positively related to flood magnitude, and time of flood generation during the tree-growth season was estimated from the radial position of anomalous growth relative to annual ring width. Reconstructing tree heights in a year of flood-ring formation gives a minimum stage estimate along local stream reaches. Some trees provided evidence of numerous floods. Those with the greatest number of flood rings grew on frequently flooded surfaces subject to flood-flow velocities of at least 1 m/s, and more typically greater than 2 m/s. Tree size, more than age, was related to flood-ring formation. Trees kept small by frequent flood damage had more flood rings than taller trees of comparable age. (USGS)

  8. Sampling benthic macroinvertebrates in a large flood-plain river: Considerations of study design, sample size, and cost

    USGS Publications Warehouse

    Bartsch, L.A.; Richardson, W.B.; Naimo, T.J.

    1998-01-01

    Estimation of benthic macroinvertebrate populations over large spatial scales is difficult due to the high variability in abundance and the cost of sample processing and taxonomic analysis. To determine a cost-effective, statistically powerful sample design, we conducted an exploratory study of the spatial variation of benthic macroinvertebrates in a 37 km reach of the Upper Mississippi River. We sampled benthos at 36 sites within each of two strata, contiguous backwater and channel border. Three standard ponar (525 cm(2)) grab samples were obtained at each site ('Original Design'). Analysis of variance and sampling cost of strata-wide estimates for abundance of Oligochaeta, Chironomidae, and total invertebrates showed that only one ponar sample per site ('Reduced Design') yielded essentially the same abundance estimates as the Original Design, while reducing the overall cost by 63%. A posteriori statistical power analysis (alpha = 0.05, beta = 0.20) on the Reduced Design estimated that at least 18 sites per stratum were needed to detect differences in mean abundance between contiguous backwater and channel border areas for Oligochaeta, Chironomidae, and total invertebrates. Statistical power was nearly identical for the three taxonomic groups. The abundances of several taxa of concern (e.g., Hexagenia mayflies and Musculium fingernail clams) were too spatially variable to estimate power with our method. Resampling simulations indicated that to achieve adequate sampling precision for Oligochaeta, at least 36 sample sites per stratum would be required, whereas a sampling precision of 0.2 would not be attained with any sample size for Hexagenia in channel border areas, or Chironomidae and Musculium in both strata given the variance structure of the original samples. Community-wide diversity indices (Brillouin and 1-Simpsons) increased as sample area per site increased. The backwater area had higher diversity than the channel border area. The number of sampling sites

  9. Sediment and nutrient trapping as a result of a temporary Mississippi River floodplain restoration: The Morganza Spillway during the 2011 Mississippi River Flood

    USGS Publications Warehouse

    Kroes, Daniel; Schenk, Edward R.; Noe, Gregory; Benthem, Adam J.

    2015-01-01

    The 2011 Mississippi River Flood resulted in the opening of the Morganza Spillway for the second time since its construction in 1954 releasing 7.6 km3 of water through agricultural and forested lands in the Morganza Floodway and into the Atchafalaya River Basin. This volume, released over 54 days, represented 5.5% of the Mississippi River (M.R.) discharge and 14% of the total discharge through the Atchafalaya River Basin (A.R.B.) during the Spillway operation and 1.1% of the M.R. and 3.3% of the A.R.B. 2011 water year discharge. During the release, 1.03 teragrams (Tg) of sediment was deposited on the Morganza Forebay and Floodway and 0.26 Tg was eroded from behind the Spillway structure. The majority of deposition (86 %) occurred in the Forebay (upstream of the structure) and within 4 km downstream of the Spillway structure with minor deposition on the rest of the Floodway. There was a net deposition of 26 × 10−4 Tg of N and 5.36 × 10−4 Tg of P, during the diversion, that was equivalent to 0.17% N and 0.33% P of the 2011 annual M.R. load. Median deposited sediment particle size at the start of the Forebay was 13 μm and decreased to 2 μm 15 km downstream of the Spillway structure. Minimal accretion was found greater than 4 km downstream of the structure suggesting the potential for greater sediment and nutrient trapping in the Floodway. However, because of the large areas involved, substantial sediment mass was deposited even at distances greater than 30 km. Sediment and nutrient deposition on the Morganza Floodway was limited because suspended sediment was quickly deposited along the flowpath and not refreshed by incremental water exchanges between the Atchafalaya River (A.R.) and the Floodway. Sediment and nutrient trapping could have been greater and more evenly distributed if additional locations of hydraulic input from and outputs to the A.R. (connectivity) were added.

  10. Using Canopy Temperature to Infer Hydrologic Processes in Floodplain Forests

    NASA Astrophysics Data System (ADS)

    Lemon, M. G.; Allen, S. T.; Keim, R.; Edwards, B. L.; King, S. L.

    2015-12-01

    Decreased water availability due to hydrologic modifications, groundwater withdrawal, and climate change threaten the hydrological architecture of floodplain forests globally. The relative contributions of different sources of water (e.g., precipitation, surface flooding, and groundwater) to soil moisture on floodplains is poorly constrained, so identification of areas of water stress within a floodplain can provide valuable information about floodplain hydrology. Canopy temperature is a useful indicator of moisture stress and has long been used in agricultural and natural landscapes. Accordingly, thermal infrared (TIR) remote sensing data (spatial resolution of 1 km) from NASA's MODIS sensor was used to examine patterns of spatiotemporal variation in water stress in two floodplain forests over 12 growing seasons. On the upper Sabine River floodplain, Texas, increasing rainfall-derived soil moisture corresponded with increased heterogeneity of LST but there was weak association between river stage and heterogeneity. On the lower White River floodplain, Arkansas, distinct differences in LST between two reaches were observed during low flow years, while little relationship was observed between LST spatial variability and rainfall-derived soil moisture on either reach. The differences in hydrological control on these floodplain ecosystems have important ramifications for varying resilience to climate change and water resource management.

  11. Sedimentation patterns across a Coastal Plain floodplain: The importance of hydrogeomorphic influences and cross-floodplain connectivity

    NASA Astrophysics Data System (ADS)

    Kaase, Christopher T.; Kupfer, John A.

    2016-09-01

    The floodplains of large Coastal Plain rivers in the southeastern U.S. are important long-term storage sites for alluvial sediment and nutrients. Yet considerable uncertainty surrounds sediment dynamics on many large river floodplains and, in particular, the local scale factors that affect the flux of sediment and nutrients from rivers onto their floodplains and their subsequent deposition. This research quantifies short-term rates of sediment deposition from 2012 to 2014 on floodplain sites at Congaree National Park using feldspar pads. Sediment deposition rates ranged from 0.1 to 15.6 cm (median = 1.46 cm) and were closely associated with inundation frequency and geomorphic position. Cross-floodplain distributary channels served as particularly important conduits for moving sediment onto the floodplain. Physical and chemical analyses of soil samples demonstrated that the most flood-exposed sites had higher major nutrient and micronutrient levels (especially of phosphorus) and more diverse nutrient compositions. This research advances current understandings of lateral floodplain connectivity by demonstrating the complex effects of regional hydrology and local floodplain environmental characteristics on the supply of sediment and nutrients.

  12. The influence of floodplains on mercury availability

    SciTech Connect

    Wallschlaeger, D.; Wilken, R.D.

    1997-09-01

    The floodplains of the German river Elbe affect the mercury distribution in the river system in two different ways: they act both as a medium-term sink and as a long-term source. The large amounts of mercury deposited onto the floodplains during annual floodings are first effectively fixed in the soils, rendering them basically unavailable. Sequential extraction experiments reveal that only a small fraction of the mercury (< 3%) is present in available forms, whereas the vast majority is associated with humic substances or present in sulfidic binding forms. After deposition, a small fraction of the total mercury is gradually remobilized into the aqueous phase bound passively to water-soluble humic acids. The availability of mercury in these complexes is still low, since environmental influences such as changes in pH or redox potential and competition with other cations do not cause any mercury liberation. In the next step, reactions in the aqueous phase lead to the formation of the highly available volatile species Hg{sup 0} and dimethylmercury (DMM). Their evaporation gives rise to a strong mercury flux from the floodplains into the atmosphere. Preliminary mass balances indicate that the majority of the deposited mercury stays bound in the floodplain soils,