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1
Martin, Simon, Stefan Klingler, Peter Dietrich, Carsten Leven, and Olaf A. Cirpka. "Structural controls on the hydrogeological functioning of a floodplain." Hydrogeology Journal 28, no. 8 (August 22, 2020): 2675–96. http://dx.doi.org/10.1007/s10040-020-02225-8.
Анотація:
AbstractFloodplains are often conceptualized as homogeneous sediment bodies which connect streams with their respective catchment and buffer agricultural inputs. This has led to a general bias within the hydrological community towards research on sites where the floodplain is a clear conduit for groundwater flow. In humid temperate regions of central Europe, floodplains have experienced rapid environmental changes since the last glaciation, yielding significant bedrock weathering and predominantly fine-grained, highly stratified hillslope and floodplain sediments. Such heterogeneous sedimentary architecture leads to conceptual ambiguities in the interpretation of the hydrogeological functioning of floodplains, thus raising the question: Do floodplains act as barriers or conduits to groundwater flow? This study analyzes the Ammer floodplain close to Tübingen in south-western Germany as a representative mid-section floodplain in a temperate climate where the regional bedrock-geology is dominated by mudstones. Geological, geophysical, and geochemical characterization and monitoring techniques were combined to shed light on the internal geological structure as a key control modulating the floodplain hydrology. Two partially separate groundwater systems were identified: a gravel body at the bottom of the Quaternary sediments and a Holocene confined tufaceous aquifer, separated by low-permeability clays. Despite flow being predominantly along-valley, sulfate concentrations in the floodplain aquifers showed evidence of a strong connection to the gypsum-bearing hillslope, particularly where tributary valley sediments are present (e.g., alluvial fans). Results from a floodplain water balance suggest the hillslope- and floodplain-aquifer material act as a barrier to hillslope groundwater recharge, where a large fraction may be bypassing the local floodplain groundwater system.
2
Baldan, Damiano, Matthias Pucher, Elmira Akbari, Thomas Hein, and Gabriele Weigelhofer. "Effects of Two-Stage Ditch and Natural Floodplains on Sediment Processes Driven by Different Hydrological Conditions." Water 13, no. 15 (July 27, 2021): 2046. http://dx.doi.org/10.3390/w13152046.
Анотація:
The two-stage ditch is a river restoration technique that aims at improving the sediment regime and lateral channel connectivity by recreating a small floodplain alongside a stream reach. This study aimed to analyze the efficiency of a two-stage ditch in improving the stream sediment structure and functions under different hydrological conditions (baseflow, post-bankfull, post-flood). Stream sediments were collected in channel sections adjacent to the two-stage ditch, adjacent to a natural floodplain along channelized reaches without inundation areas. Grain sizes, organic matter content and phosphorous (P) fractions were analyzed along with functional parameters (benthic respiration rate and P adsorption capacity, EPC0). The reach at the two-stage ditch showed no changes in sediment texture and stocks, while the floodplain reach showed higher fines and organic matter content under all hydrological conditions. The sediments in degraded reaches were more likely to be P sources, while they were more in equilibrium with the water column next to the natural floodplains and the two-stage ditch. Only functional parameters allowed for assessing the restoration effects on improving the sediment stability and functionality. Due to its sensitivity, the use of P adsorption capacity is recommended in future studies aiming at evaluating the response of river sediments to restoration measures under different hydrological conditions.
3
Manh, N. V., B. Merz, and H. Apel. "Sedimentation monitoring including uncertainty analysis in complex floodplains: a case study in the Mekong Delta." Hydrology and Earth System Sciences Discussions 10, no. 1 (January 11, 2013): 325–73. http://dx.doi.org/10.5194/hessd-10-325-2013.
Анотація:
Abstract. Quantity and quality of sediment deposition in complex floodplains are affected by many uncertain factors, ranging from suspended sediment transport dynamics in rivers and floodplain channel interactions to internal floodplain processes. In consequence, any point measurement of sedimentation in floodplains contains a high degree of uncertainty calling for a careful analysis of the measured data. However, uncertainty analyses are not documented in publications on floodplain sedimentation data. Therefore the presented work illustrates a field sampling strategy aiming at the quantification of uncertainties associated to sediment deposition data, as well as the spatial variability of sediments deposition on floodplains. The study was performed in the Mekong Delta (MD), being an example for a large and complex floodplain with a high degree of anthropogenic disturbances. We present a procedure for the quantification of the uncertainty associated to the data, based on the design of the monitoring campaign and floodplain characteristics. Sediment traps were distributed strategically over the floodplain in clusters of three mat traps representing one monitoring point. The uncertainty originating from collection of the traps in ponding water is quantified by lab experiments. The uncertainty of a single monitoring point is then quantified in a Monte Carlo simulation, propagating the uncertainty from the different uncertainty sources to final uncertainty bounds of the monitored sediment data. For the case study area, it is shown that there are no correlations in the spatial distribution of sedimentation in floodplains. This can be explained by the highly complex channel and dike system and the high number of hydraulic structures. However, it can be shown that within single floodplain compartments the spatial deposition variability depends on the dike levels and operation and location of hydraulic structures.
4
Kretz, Lena, Katinka Koll, Carolin Seele-Dilbat, Fons van der Plas, Alexandra Weigelt, and Christian Wirth. "Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment." PLOS ONE 16, no. 3 (March 18, 2021): e0248320. http://dx.doi.org/10.1371/journal.pone.0248320.
Анотація:
Sediment retention is a key ecosystem function provided by floodplains to filter sediments and nutrients from the river water during floods. Floodplain vegetation is an important driver of fine sediment retention. We aim to understand which structural properties of the vegetation are most important for capturing sediments. In a hydraulic flume experiment, we investigated this by disentangling sedimentation on and underneath 96 vegetation patches (40 cm x 60 cm). We planted two grass and two herb species in each patch and conducted a full-factorial manipulation of 1) vegetation density, 2) vegetation height, 3) structural diversity (small-tall vs tall-tall species combinations) and 4) leaf pubescence (based on trait information). We inundated the vegetation patches for 21 h in a flume with silt- and clay-rich water and subsequently measured the amount of accumulated sediment on the vegetation and on a fleece as ground underneath it. We quantified the sediment by washing it off the biomass and off the fleece, drying the sediment and weighting it. Our results showed that all manipulated vegetation properties combined (vegetation density and height, and the interaction of structural diversity and leaf pubescence) explained sedimentation on the vegetation (total R2 = 0.34). The sedimentation underneath the vegetation was explained by the structural diversity and the leaf pubescence (total R2 = 0.11). We further found that vegetation biomass positively affected the sedimentation on and underneath the vegetation. These findings are crucial for floodplain management strategies with the aim to increase sediment retention. Based on our findings, we can identify management strategies and target plant communities that are able to maximize a floodplain’s ability to capture sediments.
5
Hallberg, Lukas, Faruk Djodjic, and Magdalena Bieroza. "Phosphorus supply and floodplain design govern phosphorus reduction capacity in remediated agricultural streams." Hydrology and Earth System Sciences 28, no. 2 (January 26, 2024): 341–55. http://dx.doi.org/10.5194/hess-28-341-2024.
Анотація:
Abstract. Agricultural headwater streams are important pathways for diffuse sediment and nutrient losses, requiring mitigation strategies beyond in-field measures to intercept the transport of pollutants to downstream freshwater resources. As such, floodplains can be constructed along existing agricultural streams and ditches to improve fluvial stability and promote deposition of sediments and particulate phosphorus. In this study, we evaluated 10 remediated agricultural streams in Sweden for their capacity to reduce sediment and particulate phosphorus export and investigated the interplay between fluvial processes and phosphorus dynamics. Remediated streams with different floodplain designs (either on one side or both sides of the channel, with different width and elevation) were paired with upstream trapezoidal channels as controls. We used sedimentation plates to determine seasonal patterns in sediment deposition on channel beds and floodplains and monthly water quality monitoring. This was combined with continuous flow discharge measurements to examine suspended sediment and particulate phosphorus dynamics and reduction along reaches. Remediated streams with floodplains on both sides of the channel reduced particulate phosphorus concentrations and loads (−54 µg L−1, −0.21 kg ha−1 yr−1) along reaches, whereas increases occurred along streams with one-sided floodplains (27 µg L−1, 0.09 kg ha−1 yr−1) and control streams (46.6 µg L−1). Sediment deposition in remediated streams was five times higher on channel beds than on floodplains and there was no evident lateral distribution of sediments from channel to floodplains. There was no effect from sediment deposition on particulate phosphorus reduction, suggesting that bank stabilization was the key determinant for phosphorus mitigation in remediated streams, which can be realized with two-sided but not one-sided floodplains. Further, the overall narrow floodplain widths likely restricted reach-scale sediment deposition and its impact on P reductions. To fully understand remediated streams' potential for reductions in both nitrogen and different phosphorus species and to avoid pollution swapping effects, there is a need to further investigate how floodplain design can be optimized to achieve a holistic solution towards improved stream water quality.
6
Zaharova, Ellina D., and Vladimir R. Belyaev. "Contribution Of The Different Sources To The Formation Of Alluvial Sediments In The Selenga River Delta. (Eastern Siberia, Russia)." GEOGRAPHY, ENVIRONMENT, SUSTAINABILITY 15, no. 4 (January 18, 2023): 222–31. http://dx.doi.org/10.24057/2071-9388-2022-098.
Анотація:
Unraveling sources of sediment supply, their temporal and spatial variability is of key importance to determine origin of deposits and to explore the formation mechanism of Selenga Delta landscape units. From an environmental point of view this solution would help to identify the particle-bound pollution sources. We used geochemical fingerprinting (the FingerPro R package), which is a modern quantitative implementation of the method of sedimentary provenance analysis. The main aim was to recognize the main patterns of sediment and associated particle-bound pollutants transport and deposition within the delta. At the old floodplain from 55% to 90% of sediments were delivered from the eroded floodplain and terrace banks upstream and only about 10-15% originates from the remote basin sources. Sedimentary environment in the Khlystov Zaton reveals a greater variety than on the floodplains. 40% of sediments from the upper 5 cm-layer originated from the flood, taking place in 2013, and 30% were the product of floodplain and terraces banks erosion. Nevertheless, analysis of the fine-grained component of suspended sediment sets the material from eroded floodplain banks as the dominant source of accumulation within the delta. This means that the self-absorption is the leading process in the Selenga delta at the moment. Heavy metals and metalloids accumulates in the lower reaches of the Selenga on the floodplain surface, deltaic lakes and oxbows during high floods. Runoff decrease during floods can lead to the release of pollutants into the Lake Baikal.
7
Jílek, Pavel, Jaroslava Melková, Eliška Růžičková, Jan Šilar, and Antonín Zeman. "Radiocarbon Dating of Holocene Sediments: Flood Events and Evolution of the Labe (Elbe) River in Central Bohemia (Czech Republic)." Radiocarbon 37, no. 2 (1995): 131–37. http://dx.doi.org/10.1017/s0033822200030563.
Анотація:
We studied the structure and development of the Holocene floodplain of the Labe (Elbe) River by radiocarbon dating sections of the upper and middle courses of the river. We focused on geomorphological and sedimentological conditions, mineralogy and the chemical composition of sediments. We established the stratigraphy of the Holocene deposits of the floodplain. The results of our investigation of fluvial sediments imply that several abrupt changes in temperature and precipitation occurred during the Holocene. These changes led to intervals of hydrological disequilibrium, which caused the formation of two Holocene terraces and a contemporaneous floodplain. The lower terrace was flooded and covered with sediments upon which the recent floodplain formed. During the Holocene, there were four periods during which large tree trunks were deposited in the fluvial sediments, indicating periods of extensive flooding. The supposition that these events were of more global scale is supported by the results of investigations made on the Holocene floodplains of other regions.
8
Notebaert, B., G. Houbrechts, G. Verstraeten, N. Broothaerts, J. Haeckx, M. Reynders, G. Govers, F. Petit, and J. Poesen. "Fluvial architecture of Belgian river systems in contrasting environments: implications for reconstructing the sedimentation history." Netherlands Journal of Geosciences - Geologie en Mijnbouw 90, no. 1 (August 2011): 31–50. http://dx.doi.org/10.1017/s0016774600000652.
Анотація:
AbstractAccurate dating is necessary to get insight in the temporal variations in sediment deposition in floodplains. The interpretation of such dates is however dependent on the fluvial architecture of the floodplain. In this study we discuss the fluvial architecture of three contrasting Belgian catchments (Dijle, Geul and Amblève catchment) and how this influences the dating possibilities of net floodplain sediment storage. Although vertical aggradation occurred in all three floodplains during the last part of the Holocene, they differ in the importance of lateral accretion and vertical aggradation during the entire Holocene. Holocene floodplain aggradation is the dominant process in the Dijle catchment. Lateral reworking of the floodplain sediments by river meandering was limited to a part of the floodplain, resulting in stacked point bar deposits. The fluvial architecture allows identifying vertical aggradation without erosional hiatuses. Results show that trends in vertical floodplain aggradation in the Dijle catchment are mainly related to land use changes. In the other two catchments, lateral reworking was the dominant process, and channel lag and point bar deposits occur over the entire floodplain width. Here, tracers were used to date the sediment dynamics: lead from metal mining in the Geul and iron slag from ironworks in the Amblève catchment. These methods allow the identification of two or three discrete periods, but their spatial extent and variations is identified in a continuous way. The fluvial architecture and the limitation in dating with tracers hampered the identification of dominant environmental changes for sediment dynamics in both catchments. Dating methods which provide only discrete point information, like radiocarbon or OSL dating, are best suited for fluvial systems which contain continuous aggradation profiles. Spatially more continuous dating methods, e.g. through the use of tracers, allow to reconstruct past surfaces and allow to reconstruct reworked parts of the floodplain. As such they allow a better reconstruction of past sedimentation rates in systems with important lateral reworking.
9
ŠORŠA, Ajka, Teja ČERU, Zsófia KOVÁCS, Gyozo JORDAN, Katalin Mária DUDÁS, and Peter SZABÓ. "ASSESSMENT OF RIVER SEDIMENT QUALITY ACCORDING TO THE EU WATER FRAMEWORK DIRECTIVE IN LOWLAND FLUVIAL CONDITIONS. A CASE STUDY IN THE DRAVA RIVER AREA, DANUBE RIVER BASIN." Carpathian Journal of Earth and Environmental Sciences 17, no. 2 (August 31, 2022): 459–68. http://dx.doi.org/10.26471/cjees/2022/017/235.
Анотація:
The EU Water Framework Directive requires the monitoring and evaluation of surface water sediment quality based on the assessment of risk posed by contamination on the biotic receptors. Fluvial sediments are important receptors of hazardous substances (HSs) pollution from the upstream catchment areas in the Danube River Basin (DRB). For the development of systematic sediment quality monitoring and evaluation, the Drava River region on the border of Hungary and Croatia was selected as a test area representative of lowland hydromorphological conditions. Overbank (floodplain) sediments and river bottom sediments (stream sediments) were sampled at two depths at 9 locations in the test area. Eight heavy metal(oid)s were analyzed As, Cd, Cr, Cu, Hg, Ni, and Zn as hazardous substances. The sediment quality assessment was carried out according to the 2013/39/EU Directive and EU Water Framework Directive standards. Most of the analysed HS concentrations in river bottom sediment and overbank (floodplain) sediments fall within the limits of environmental quality standards (EQS). Results show that there is no significant differences in metal(oid) HS concentrations among the various sediment types and between shallow (0-5cm) and deeper (stream sediment: 5-10cm; floodplain sediment: 40-50cm) sediment which suggests that the large lowland Drava River fluvial system is an extensive single fluvial system with homogeneous distribution of sediments and the associated contaminants. Specifically, the studied sediments in the tributaries of the Drava River do not seem to be contaminated with metal(oid) hazardous substances but at certain sites concentrations are elevated above the environmental limit values, especially for As and Zn, and to lesser extent for Cr. The data analysis techniques used enabled the identification of sites with anthropogenic pollution and the recognition of regional pattern in HSs distribution.
10
Berger, Glenn W., and Don J. Easterbrook. "Thermoluminescence dating tests for lacustrine, glaciomarine, and floodplain sediments from western Washington and British Columbia." Canadian Journal of Earth Sciences 30, no. 9 (September 1, 1993): 1815–28. http://dx.doi.org/10.1139/e93-160.
Анотація:
To help further develop reliable procedures for accurate thermoluminescence (TL) dating of Quaternary waterlaid sediments, we tested TL dating procedures on sediment types rarely examined: six glaciolacustrine samples, three samples of glaciomarine drift, and eight samples of floodplain deposits. We used the partial-bleach (R-beta/gamma) technique applied to fine-silt polymineral grains. Results from our younger known-age glaciolacustrine sediments confirm earlier observations that only the clayey laminae are generally suitable for TL dating. A clayey lamina older than ca. 140 – 150 ka produced no age underestimation, and this result (ca. 300 ka) suggests that such older lake sediments are probably suitable for TL dating. Two proximal samples of glaciomarine drift produced large TL age overestimates, whereas the single distal glaciomarine-drift sample yielded an expected age (177 ± 38 ka), suggesting that follow-up studies are warranted. Our results for eight flood-plain samples confirm that zeroing of light-sensitive TL is more likely to be effective for sediments deposited in quiet, ponded water on the floodplain than for proximal sediments deposited from turbid floodwater. TL age estimates for floodplain sediments of the regional Whidbey Formation are consistent with its expected last-interglacial age, and those for two samples from stratigraphically older beds are consistent with deposition near or beyond 200 ka. Two of our younger samples (one lacustrine and one floodplain) gave TL age underestimates, perhaps because of use of ultraviolet TL emissions for these samples.
11
Claret, C., A. J. Boulton, M. J. Dole-Olivier, and P. Marmonier. "Functional processes versus state variables: interstitial organic matter pathways in floodplain habitats." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 8 (August 1, 2001): 1594–602. http://dx.doi.org/10.1139/f01-106.
Анотація:
We assessed the potential rates of two microbial processes, cellulose decomposition potential (CDP) and hydrolytic activity, to explore the relationship of these functional measurements with several state variables of organic matter. Samples were collected from two interstitial sites in the main channel of the Rhône River and 10 sites on the alluvial floodplain representing five habitat types defined by sediment size (fine versus coarse sediments) and interstitial water origin (surface water versus groundwater). Although sites with fine sediments had more interstitial total organic matter, refractory and biodegradable dissolved organic carbon concentrations did not differ among habitat types. Unlike the floodplain, the main channel had high CDP and low hydrolytic activity. In the floodplain, functional measurements varied consistently, and both CDP and hydrolytic activity were lowest at the sites with coarse sediments. Our data imply that microbially mediated processes are different in the main channel and the floodplain and that low levels of organic matter in the coarse sediments are probably due to slow rates of accrual rather than rapid rates of decomposition. Furthermore, the lack of correlation between functional variables and dissolved organic carbon concentrations illustrates the dangers of interpreting ecosystem processes or ecological integrity based solely on state variables.
12
Elznicová, Jitka, Tomáš Matys Grygar, Jan Popelka, Martin Sikora, Petr Novák, and Michal Hošek. "Threat of Pollution Hotspots Reworking in River Systems: Case Study of the Ploučnice River (Czech Republic)." ISPRS International Journal of Geo-Information 8, no. 1 (January 16, 2019): 37. http://dx.doi.org/10.3390/ijgi8010037.
Анотація:
As fluvial pollution may endanger the quality of water and solids transported by rivers, mapping and evaluation of historically polluted fluvial sediments is an urgent topic. The Ploučnice River and its floodplain were polluted by local uranium mining from 1971–1989. We have studied this river since 2013 using a combination of diverse methods, including geoinformatics, to identify pollution hotspots in floodplains and to evaluate the potential for future reworking. Archival information on pollution history and past flooding was collected to understand floodplain dynamics and pollution heterogeneity. Subsequently, a digital terrain model based on laser scanning data and data analysis were used to identify the sites with river channel shifts. Finally, non-invasive geochemical mapping was employed, using portable X-ray fluorescence and gamma spectrometers. The resulting datasets were processed with geostatistical tools. One of the main outputs of the study was a detailed map of pollution distribution in the floodplain. The results showed a relationship between polluted sediment deposition, past channel shifts and floodplain development. We found that increased concentration of pollution occurred mainly in the cut-off meanders and lateral channel deposits from the mining period, the latter in danger of reworking (reconnecting to the river) in the coming decades.
13
Wang, H., and X. Jia. "Selective deposition response to aeolian-fluvial sediment supply in the desert braided channel of the Upper Yellow River, China." Natural Hazards and Earth System Sciences Discussions 3, no. 2 (February 10, 2015): 1269–90. http://dx.doi.org/10.5194/nhessd-3-1269-2015.
Анотація:
Abstract. Rivers flow across aeolian dunes and develop braided stream channels. Both aeolian and fluvial sediment supplies regulate sediment transport and deposition in such a cross-dune braided river. Here we show a significant selective deposition in response to both aeolian and fluvial sediment supplies in the Ulan Buh desert braided channel. This selective deposition developed by the interaction between the flows and the Aeolian-fluvial sediment supplies, making the coarser sediments (> 0.08 mm) from aeolian sand supply and bank erosion to accumulate in the channel center and the finer fluvial sediments (< 0.08 mm) to be deposited on the bar and floodplain surfaces and forming a coarser-grained thalweg bed bounded by finer-grained floodplain surfaces. This lateral selective deposition reduces the downstream sediment transport and is a primary reason for the formation of "above-ground river" in the braided reach of the Upper Yellow River in response to aeolian and fluvial sediment supplies.
14
Makhinov, A. N., Liu Shuguang, A. F. Makhinova, and Chaomeng Dai. "Impact of Flooding and Urbanisation on the Content of Heavy Metals in the Water and Bottom Sediments of the Amur River." Ecology and Industry of Russia 24, no. 12 (December 1, 2020): 32–38. http://dx.doi.org/10.18412/1816-0395-2020-12-32-38.
Анотація:
The impact of floods on the migration activity of elements coming from urbanized territories to the Amur river was assessed. The influence of large cities on pollution of water and floodplain ecosystems is revealed. The content of heavy metals in water, bottom sediments, and small watercourses draining urban areas is characterized. The processes of sediment accumulation in the floodplain, their influence on the redistribution of elements and geochemical transformations in the soil space of floodplain soils are studied. Conditions for the accumulation of heavy metals in soils are described, their concentration levels and migration activity are determined. The role of organic matter in swamps and silts on water pollution and bottom sediments of the Amur river is shown. It was found that the main mass transfer of soluble substances and pollutants dispersed fractions of nailc is carried out by water flow during floods.
15
Hostache, R., C. Hissler, P. Matgen, C. Guignard, and P. Bates. "A 2-D hydro-morphodynamic modelling approach for predicting suspended sediment propagation and related heavy metal contamination in floodplain: a sensitivity analysis." Hydrology and Earth System Sciences Discussions 11, no. 2 (February 10, 2014): 1741–76. http://dx.doi.org/10.5194/hessd-11-1741-2014.
Анотація:
Abstract. Fine sediments represent an important vector of pollutant diffusion in rivers. When deposited in floodplains and riverbeds they can be responsible for soil pollution. In this context, this paper proposes a hydro-morphodynamic modelling exercise aiming at predicting transport and diffusion of fine sediments and dissolved pollutants. The model is based upon the Telemac hydro-informatic system (dynamical coupling Telemac-2D-Sysiphe). As empirical and semi-empirical parameters need to be calibrated for such a modelling exercise, a sensitivity analysis is proposed. In parallel to the modelling exercise, an extensive hydrological/geochemical database has been set up during two flood events. The main sensitive parameters were found to be the hydraulic friction coefficient and the sediment particle settling velocity in water. Using the two monitored hydrological events as calibration and validation, it was found that the model is able to satisfyingly predict suspended sediment and dissolve pollutant transport in the river channel. In addition, a qualitative comparison between simulated sediment deposition in the floodplain and a soil contamination map shows that the preferential zones for deposition identified by the model are realistic.
16
Cartwright, Ian, and Harald Hofmann. "Using radon to understand parafluvial flows and the changing locations of groundwater inflows in the Avon River, southeast Australia." Hydrology and Earth System Sciences 20, no. 9 (September 6, 2016): 3581–600. http://dx.doi.org/10.5194/hess-20-3581-2016.
Анотація:
Abstract. Understanding the location and magnitude of groundwater inflows to rivers is important for the protection of riverine ecosystems and the management of connected groundwater and surface water systems. This study utilizes 222Rn activities and Cl concentrations in the Avon River, southeast Australia, to determine the distribution of groundwater inflows and to understand the importance of parafluvial flow on the 222Rn budget. The distribution of 222Rn activities and Cl concentrations implies that the Avon River contains alternating gaining and losing reaches. The location of groundwater inflows changed as a result of major floods in 2011–2013 that caused significant movement of the floodplain sediments. The floodplain of the Avon River comprises unconsolidated coarse-grained sediments with numerous point bars and sediment banks through which significant parafluvial flow is likely. The 222Rn activities in the Avon River, which are locally up to 3690 Bq m−3, result from a combination of groundwater inflows and the input of water from the parafluvial zone that has high 222Rn activities due to 222Rn emanation from the alluvial sediments. If the high 222Rn activities were ascribed solely to groundwater inflows, the calculated net groundwater inflows would exceed the measured increase in streamflow along the river by up to 490 % at low streamflows. Uncertainties in the 222Rn activities of groundwater, the gas transfer coefficient, and the degree of hyporheic exchange cannot explain a discrepancy of this magnitude. The proposed model of parafluvial flow envisages that water enters the alluvial sediments in reaches where the river is losing and subsequently re-enters the river in the gaining reaches with flow paths of tens to hundreds of metres. Parafluvial flow is likely to be important in rivers with coarse-grained alluvial sediments on their floodplains and failure to quantify the input of 222Rn from parafluvial flow will result in overestimating groundwater inflows to rivers.
17
Govenor, Heather, W. Cully Hession, Tyler A. Keys, C. Nathan Jones, Ryan D. Stewart, and Leigh-Anne H. Krometis. "Evaluating Rare Earth Elements as Tracers of Fluvial Processes: Fine Sediment Transport and Deposition in a Small Stream." Transactions of the ASABE 64, no. 3 (2021): 905–18. http://dx.doi.org/10.13031/trans.14358.
Анотація:
HighlightsNatural sediments labeled with rare earth elements can effectively be used as tracers for quantifying fine sediment transport and deposition.Two artificial floods in a small stream (100 ha watershed, 1.5 year return flow of 515 L s-1) transported fine sediment 0 m to >850 m at a maximum flow rate of 55 L s-1.Sediment deposition per unit area was greater in the channel than in the near-channel floodplain.Use of two distinct tracers demonstrated resuspension extent during sequential high-flow events.Presence of large wood in the channel was associated with reduced streamflow rate, decreased suspended sediment transport velocity, increased channel sediment deposition, and reduced near-floodplain sediment deposition.Abstract. Effective sediment management requires an understanding of the lag time between best management practice implementation and observable changes in the target water body. To improve our understanding of sediment lag times, we tested a method to label locally sourced sediments with rare earth elements to quantify fine sediment flow-through and storage in fluvial systems. We injected sediments labeled with lanthanum and ytterbium into a small stream during two artificial flood events. During the floods, we collected and quantified suspended sediments and sediment deposition in the stream channel and floodplain at four cross-sections within our study reach. Two down-gradient (90 m and 850 m) time-integrated suspended sediment samplers evaluated total travel distance. Sediment tracer observations of particle transport distances ranged from 0 m to at least 850 m at a maximum flow rate of 55 L s-1 (stream 1.5 year flow was 515 L s-1). Sediment deposition per unit area was greater in the channel than in the floodplain. The majority of sediment tracer mass injected into the stream entered storage within the first 69 m of the reach. Some particles that deposited following the first flood were resuspended and either transported downstream or redeposited within the study reach. Our results support the further use of rare earth elements as sediment tracers to inform water quality and sediment transport models, and to provide estimates of lag times between management actions and downstream improvements. Keywords: Fine sediment, Flood, Fluvial geomorphology, Lag time, Large wood, Rare earth elements, Sediment deposition, Sediment transport, Tracer.
18
HUYBRECHTS, Willy. "Post-pleniglacial floodplain sediments in Central Belgium." Quaternary geology of Belgium: new perspectives 2, no. 1-2 (April 1, 2000): 29–37. http://dx.doi.org/10.20341/gb.2014.009.
Анотація:
This paper presents an outline of the floodplain sediments which dominated the river environment during the last 13,000 years in the western parts of Central Belgium. It is based on literature, with special reference to the Mark River basin. River landscapes and related floodplain sediments are a combined result of changing external factors such as climate and human activity, and prevailing local geological and topographical conditions. The development of the vegetation predominantly controls the sediment and water fluxes in the catchment. After the Pleniglacial, a system of palaeovalleys developed as a result of a non-equilibrium between vegetation and climate. For more than 10,000 years, this system dominated the river landscape, while gradually being filled with organic material and sediments. Three infilling phases can be distinguished: the Gully facies, the Organic and tufa facies, and the Fluvial clay facies. The Gully facies reflects an initial time period of fluvial activity, and occupies the lowermost parts of the palaeovalley. From 9000 BP onwards, forest swamps occupied the river plains, reflecting very stable conditions in the catchments. The Organic and tufa facies was formed. During the second half of the Atlanticum, from about 6000 BP onwards, human agricultural activities greatly affected the river landscape and the hydrological system. The forest swamps disappeared and were gradually replaced by open water. The deposition of the Fluvial clay facies concluded the filling of the palaeovalley. Medieval clearings in the catchments, less than 1200 years ago, disrupted the originally stable hydrological regime of the river. The Surface loam facies was deposited during inundations, independent of the palaeovalley system.
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Maciel, Daniel, Evlyn Novo, Lino Sander de Carvalho, Cláudio Barbosa, Rogério Flores Júnior, and Felipe de Lucia Lobo. "Retrieving Total and Inorganic Suspended Sediments in Amazon Floodplain Lakes: A Multisensor Approach." Remote Sensing 11, no. 15 (July 24, 2019): 1744. http://dx.doi.org/10.3390/rs11151744.
Анотація:
Remote sensing imagery are fundamental to increasing the knowledge about sediment dynamics in the middle-lower Amazon floodplains. Moreover, they can help to understand both how climate change and how land use and land cover changes impact the sediment exchange between the Amazon River and floodplain lakes in this important and complex ecosystem. This study investigates the suitability of Landsat-8 and Sentinel-2 spectral characteristics in retrieving total (TSS) and inorganic (TSI) suspended sediments on a set of Amazon floodplain lakes in the middle-lower Amazon basin using in situ Remote Sensing Reflectance (Rrs) measurements to simulate Landsat 8/OLI (Operational Land Imager) and Sentinel 2/MSI (Multispectral Instrument) bands and to calibrate/validate several TSS and TSI empirical algorithms. The calibration was based on the Monte Carlo Simulation carried out for the following datasets: (1) All-Dataset, consisting of all the data acquired during four field campaigns at five lakes spread over the lower Amazon floodplain (n = 94); (2) Campaign-Dataset including samples acquired in a specific hydrograph phase (season) in all lakes. As sample size varied from one season to the other, n varied from 18 to 31; (3) Lake-Dataset including samples acquired in all seasons at a given lake with n also varying from 17 to 67 for each lake. The calibrated models were, then, applied to OLI and MSI scenes acquired in August 2017. The performance of three atmospheric correction algorithms was also assessed for both OLI (6S, ACOLITE, and L8SR) and MSI (6S, ACOLITE, and Sen2Cor) images. The impact of glint correction on atmosphere-corrected image performance was assessed against in situ glint-corrected Rrs measurements. After glint correction, the L8SR and 6S atmospheric correction performed better with the OLI and MSI sensors, respectively (Mean Absolute Percentage Error (MAPE) = 16.68% and 14.38%) considering the entire set of bands. However, for a given single band, different methods have different performances. The validated TSI and TSS satellite estimates showed that both in situ TSI and TSS algorithms provided reliable estimates, having the best results for the green OLI band (561 nm) and MSI red-edge band (705 nm) (MAPE < 21%). Moreover, the findings indicate that the OLI and MSI models provided similar errors, which support the use of both sensors as a virtual constellation for the TSS and TSI estimate over an Amazon floodplain. These results demonstrate the applicability of the calibration/validation techniques developed for the empirical modeling of suspended sediments in lower Amazon floodplain lakes using medium-resolution sensors.
20
Aalto, Rolf, and Charles A. Nittrouer. "210 Pb geochronology of flood events in large tropical river systems." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, no. 1966 (May 13, 2012): 2040–74. http://dx.doi.org/10.1098/rsta.2011.0607.
Анотація:
Floodplain sedimentation removes particles from fluvial transport and constructs stratigraphic records of flooding, biogeochemical sequestration and other aspects of the environmental history of river basins—insight that is enhanced by accurate geochronology. The natural fallout radionuclide 210 Pb, often employed to date lacustrine and marine sediments, has previously been used to determine floodplain accumulation rates over decadal-to-century time scales using the assumption that both input concentration and sediment accumulation rates are constant. We test this model in approximately 110 cores of pristine floodplains along approximately 2000 km of the Rios Beni and Mamore in northern Bolivia; over 95 per cent of the 210 Pb profiles depict individual episodic deposition events, not steady-state accumulation, requiring a revised geochronological methodology. Discrete measurements of down-core, clay-normalized adsorbed excess 210 Pb activity are coupled with a new conceptual model of 210 Pb input during floods: constant initial reach clay activity, unknown sedimentation (CIRCAUS). This enhanced methodology yields 210 Pb dates that correspond well with (i) dates determined from meteoric caps, (ii) observed dates of river bar formation, (iii) known flood dates, and (iv) dates from nearby cores along the same transect. Similar results have been found for other large rivers. The CIRCAUS method for geochronology therefore offers a flexible and accurate method for dating both episodic (decadal recurrence frequency) and constant (annual recurrence) sediment accumulation on floodplains.
21
Welti, N., E. Bondar-Kunze, M. Mair, P. Bonin, W. Wanek, G. Pinay, and T. Hein. "Mimicking floodplain reconnection and disconnection using <sup>15</sup>N mesocosm incubations." Biogeosciences 9, no. 11 (November 5, 2012): 4263–78. http://dx.doi.org/10.5194/bg-9-4263-2012.
Анотація:
Abstract. Floodplain restoration changes the nitrate delivery pattern and dissolved organic matter pool in backwaters, though the effects these changes have are not yet well known. We performed two mesocosm experiments on floodplain sediments to quantify the nitrate metabolism in two types of floodplains. Rates of denitrification, dissimilatory nitrate reduction to ammonium (DNRA) and anammox were measured using 15N-NO3 tracer additions in mesocosms of undisturbed floodplain sediments originating from (1) restored and (2) disconnected sites in the Alluvial Zone National Park on the Danube River downstream of Vienna, Austria. DNRA rates were an order of magnitude lower than denitrification and neither rate was affected by changes in nitrate delivery pattern or organic matter quality. Anammox was not detected at any of the sites. Denitrification was out-competed by assimilation, which was estimated to use up to 70% of the available nitrate. Overall, denitrification was higher in the restored sites, with mean rates of 5.7 ± 2.8 mmol N m−2 h−1 compared to the disconnected site (0.6 ± 0.5 mmol N m−2 h−1). In addition, ratios of N2O : N2 were lower in the restored site indicating a more complete denitrification. Nitrate addition had neither an effect on denitrification, nor on the N2O : N2 ratio. However, DOM (dissolved organic matter) quality significantly changed the N2O : N2 ratio in both sites. Addition of riverine-derived organic matter lowered the N2O : N2 ratio in the disconnected site, whereas addition of floodplain-derived organic matter increased the N2O : N2 ratio in the restored site. These results demonstrate that increasing floodplains hydrological connection to the main river channel increases nitrogen retention and decreases nitrous oxide emissions.
22
Yuskar, Yuniarti, Dewandra Bagus Eka Putra, and Muhammad Revanda. "Quarternary Sediment Characteristics of Floodplain area: Study Case at Kampar River, Rumbio Area and Surroundings, Riau Province." Journal of Geoscience, Engineering, Environment, and Technology 3, no. 1 (March 10, 2018): 63. http://dx.doi.org/10.24273/jgeet.2018.3.1.1226.
Анотація:
The study area is located in some floodplains of meandering river environment along the Kampar River, Rumbio. Typical morphology of meandering river that found in this area can be classified as stream channel, floodplain, abandoned channel, and sand bars deposit. Meandering river system carries sediment supply by suspended and bed - load (mixed load) in conjunction with low energy into a particular characteristic on sediment deposition. This study aims to determine the characteristics of the sediments, changes in vertical and lateral spread of sediment deposition on the floodplain environment. This study conducted by field survey using a hand auger of 1.5m - 4m depth and trenching which is a layer that has been exposed of 1-2 meters depth. Further analysis had been carried out using granulometri method and core data analysis to determine the characteristics and depositional facies. Sediment deposit that formed along the Kampar River is the result of the main channel migration of Kampar River. The characteristic of quaternary sediment facies is coarse to gravelly sand on the bottom followed by fine to very fine sand with pattern fining upwards and silt to clay and abundant terrestrial organic matter at the uppermost layer. Depositional facies are determined based on the characteristics of sediment facies which can be grouped into a stream channel, oblique accretion deposits, sand bars and overbank deposits.
23
Rimkus, A., and S. Vaikasas. "Possible ways to improve sediment deposition in the Nemunas delta." Hydrology Research 41, no. 3-4 (April 1, 2010): 346–54. http://dx.doi.org/10.2166/nh.2010.118.
Анотація:
The deposition of sediment in the inundated floodplains of rivers, particularly in their deltas, improves the water quality of the rivers themselves and of their receivers. It would be very useful if ways to increase the amount of sediment deposition could be identified. An investigation into a number of possibilities was carried out in the delta of the River Nemunas. Various factors can influence the increase or decrease of sediment deposition, e.g. the increase of water discharge flowing through the river valley, the growth of bushes on the floodplain, the building of road banks across the valley and changes in growth stages of grass (which affect its ability to entrap sediments). The effects of these factors are discussed, and the most successful ways for improvement in the Nemunas delta are proposed. Similar methods may also be applicable in other river deltas.
24
Shizuma, Kiyoshi, Wim Ikbal Nursal, and Yushi Sakurai. "Long-Term Monitoring of Radiocesium Concentration in Sediments and River Water along Five Rivers in Minami-Soma City during 2012–2016 Following the Fukushima Dai-ichi Nuclear Power Plant Accident." Applied Sciences 8, no. 8 (August 7, 2018): 1319. http://dx.doi.org/10.3390/app8081319.
Анотація:
Radiocesium monitoring in sediments and river water has been conducted along five rivers in Minami-Soma City during 2012–2016 to clarify the temporal changes of radiocesium contamination in these rivers. Sampling has been performed annually under normal flow conditions. Sediment and river water samples were collected from four or five sampling sites along each river. Gamma-ray measurements of sediments were performed using a low-background Ge detector and unfiltered river water was utilized to determine radiocesium concentration using a well-type Ge detector. The 137Cs concentration in sediments was highest at upstream sites and slowly decreased to downstream sites for all rivers reflecting the high radioactive contamination in the upstream area. Temporal decrease of the 137Cs concentration was observed in sediments and river water for each river. The effective half-lives were 1.3–2.1 y for sediments, and 0.9–2.1 y for river water from rivers with upstream dams. On the undammed river, the effective half-lives were 4.7 y and 3.7 y for sediment and river water, respectively. Much longer effective-half-lives might reflect the direct transfer of radiocesium from forests and plains to the river. The 137Cs concentration in riverbed was low in downstream areas, however, accumulation of 137Cs over the floodplain was observed. Rapid decrease of 137Cs contamination through rivers will put residents at ease, but high accumulation of radiocesium over floodplains should be noted for future river decontamination.
25
Wang, H., X. Jia, Y. Li, and W. Peng. "Selective deposition response to aeolian–fluvial sediment supply in the desert braided channel of the upper Yellow River, China." Natural Hazards and Earth System Sciences 15, no. 9 (September 2, 2015): 1955–62. http://dx.doi.org/10.5194/nhess-15-1955-2015.
Анотація:
Abstract. Rivers flow across aeolian dunes and develop braided stream channels. Both aeolian and fluvial sediment supplies regulate sediment transport and deposition in such cross-dune braided rivers. Here we show a significant selective deposition in response to both aeolian and fluvial sediment supplies in the Ulan Buh desert braided channel. The Ulan Buh desert is the main coarse sediment source for this desert braided channel, and the mean percentage of the coarser (> 0.08 mm) grains on the aeolian dunes surface is 95.34 %. The lateral selective deposition process is developed by the interaction between the flows and the aeolian–fluvial sediment supplies, causing the coarser sediments (> 0.08 mm) from aeolian sand supply and bank erosion to accumulate in the channel centre and the finer fluvial sediments (< 0.08 mm) to be deposited on the bar and floodplain surfaces, forming a coarser-grained thalweg bed bounded by finer-grained floodplain surfaces. This lateral selective deposition reduces the downstream sediment transport and is a primary reason for the formation of an "above-ground" river in the braided reach of the upper Yellow River in response to aeolian and fluvial sediment supplies.
26
Mezhevova, Alina, Yuliya Berestneva, and Alexander Belyaev. "Assessment of the using potential of water bodies clearance product – bottom sediments." E3S Web of Conferences 539 (2024): 01027. http://dx.doi.org/10.1051/e3sconf/202453901027.
Анотація:
Assessment of the using potential of water bodies clearance product – bottom sediments was carried out. Bottom sediments from Peschanyj, Dudak, Dudachenok shallow channels located at Volga-Akhtuba floodplain were used for studies. Bottom sediment samples were dried to an air-dry state at room temperature for further studies. The area of bottom sediments application was selected based on the physicochemical properties and the degree of it contamination by heavy metals and pesticides. Bottom sediments from Peschanyj and Dudachenok shallow channels have fertilizing value and correspond to calcareous sapropel of 1 and 2 suitability classes, respectively. Such bottom sediments can be used for agricultural aims.
27
Middelkoop, H. "Heavy-metal pollution of the river Rhine and Meuse floodplains in the Netherlands." Netherlands Journal of Geosciences - Geologie en Mijnbouw 79, no. 4 (December 2000): 411–27. http://dx.doi.org/10.1017/s0016774600021910.
Анотація:
AbstractThe embanked floodplains of the lower Rhine river in the Netherlands contain large amounts of heavy metals, which is a result of many years of deposition of contaminated overbank sediments. The metal pollution varies greatly between the various floodplain sections as well as in vertical direction within the floodplain soil profiles. The present contribution describes the key processes producing the spatial variability of the metal pollution in floodplain soils: (1) spatial patterns of the concentrations and deposition of Cd, Cu, Pb and Zn during a single flood, which have been determined from samples collected after a high-magnitude flood event; (2) the pollution trends of the lower Rhine over the past 150 years, which were reconstructed on the basis of metal concentrations in sediments from small ponds within the floodplain area. During the flood the largest metal depositions (0.03 g/m2 Cd, 0.7 g/m2 Cu, 1.1 g/m2 Pb and 5.0 g/m2 Zn for the Rhine) occurred along the natural levees, decreasing to about one third of these values at larger distance from the river. Deposition of heavy metals occurred since the end of the nineteenth century. Periods of maximum pollution occurred in the 1930s and 1960s, when Cu, Pb and Zn concentrations were about 6–10 times as high as background values.The resulting metal distribution in the floodplain soil profiles is illustrated by means of typical examples. Maximum metal concentrations in floodplain soils vary from 30 to 130 mg/kg for Cu, from 70 to 490 mg/kg for Pb, and from 170 to 1450 mg/kg for Zn. The lowest metal pollution is found in the distal parts of floodplain sections with low flooding frequencies, where average sedimentation rates have been less than about 5 mm/a. The largest metal accumulations occur in low-lying floodplain sections where average sedimentation rates have been more than 10 mm/a.
28
Fornasaro, Silvia, Guia Morelli, Valentina Rimondi, Cesare Fagotti, Rossella Friani, Pierfranco Lattanzi, and Pilario Costagliola. "The extensive mercury contamination in soil and legacy sediments of the Paglia River basin (Tuscany, Italy): interplay between Hg-mining waste discharge along rivers, 1960s economic boom, and ongoing climate change." Journal of Soils and Sediments 22, no. 2 (January 21, 2022): 656–71. http://dx.doi.org/10.1007/s11368-021-03129-0.
Анотація:
Abstract Purpose The extensive Hg contamination in soil and sediments occurring along the Paglia River (Central Italy) is the result of the interplay between the geomorphological changes of the river and anthropic activities, primarily associated to the exploitation of Hg-deposits in "The Monte Amiata mining district" (MAMD). The present study determines the implications of the morphological changes that occurred along the Paglia River in the last 200 years on the distribution of Hg along the floodplain and riverbed, which today represent one of the main Hg-reservoirs in the MAMD. Materials and methods The temporal changes of the Paglia riverbed and the extent of its alluvial deposits were reconstructed by a GIS-based analysis of the available maps and aerial photos. The Hg-concentration in soil and sediment samples, collected along five transects transverse to the Paglia River channel, was determined by ICP-MS. Results and discussion Samples along the investigated Paglia River segment typically show Hg-contents exceeding the Italian threshold for residential and public green soil use (1 mg kg−1). The distribution of Hg in the Paglia floodplain results from the combination of exceedance of sediment yield to the river during mining activities, that fed the floodplain with large amounts of Hg-contaminated sediments during its braided stage about 100 years ago, and the morphological changes of the river, that led to the evolution from a braided to the present-day single channel river. The magnitude of the extension of Hg-contamination, the river geomorphologic changes, and the processes of transport, deposition, and re-suspension did not allow a natural “clean up” of the river system, which shows a low resilience. Under high flow conditions, and especially in coincidence with intense rain events, large amounts of Hg stored in the overbank sediments are mobilized and redistributed, contributing to make the floodplain a secondary Hg-source. Extreme weather events, expected to intensify as a consequence of climate change, will contribute to the recurrent distribution of Hg-contaminated legacy sediments in the floodplain and along the Paglia river course. Conclusion From a water/land management perspective, the variability of the river flow, associated with an increase of extreme flood events driven by climate change, will affect the distribution of Hg-contaminated particles in the Paglia River, contributing to the Hg input into the Mediterranean Sea in the future. Graphical abstract
29
Haug, M. D., D. J. L. Forgie, R. Zitta, and B. E. Bews. "Thunder Creek mercury control." Canadian Journal of Civil Engineering 19, no. 3 (June 1, 1992): 478–91. http://dx.doi.org/10.1139/l92-058.
Анотація:
In 1978, mercury contamination was discovered in sediments near the confluence of Thunder Creek and the Moose Jaw River, in the City of Moose Jaw, Saskatchewan, Canada. A detailed investigation revealed up to 95 mg/kg of mercury in the floodplain sediments. This contamination was primarily concentrated along the north bank of Thunder Creek and in the adjacent creek sediments. The extent of the contamination indicated that it had not occurred recently, and that total removal of the mercury would be difficult and costly. Thus, a mercury control plan was initiated to remove or effectively contain 95% of the contamination. Contaminated sediments were excavated by dragline from the floodplain and placed on top of mercury contaminated surface sediment along the north bank of Thunder Creek. A soil backfill slurry trench cutoff wall was constructed along the creek through permeable soils and keyed into a low permeability clay shale to isolate the contaminated sediments. The contaminated sediments were also isolated by the construction of an interceptor ditch to direct water around the containment area past the cutoff wall. The contaminated sediments were compacted and covered with lime-modified clay and a topsoil cover which was seeded with grass. Monitoring of water and sediments along Thunder Creek and the Moose Jaw River since implementation of these control measures has shown a significant reduction in mercury levels, indicating that the control system is meeting its objectives. Key words: mercury, environment, contamination, mitigative measures, slurry trench cutoff, interceptor drains, monitoring.
30
Hauer, F. Richard, Harvey Locke, Victoria J. Dreitz, Mark Hebblewhite, Winsor H. Lowe, Clint C. Muhlfeld, Cara R. Nelson, Michael F. Proctor, and Stewart B. Rood. "Gravel-bed river floodplains are the ecological nexus of glaciated mountain landscapes." Science Advances 2, no. 6 (June 2016): e1600026. http://dx.doi.org/10.1126/sciadv.1600026.
Анотація:
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.
31
Aliyu, Ahmed Sidi, Nuhu Musa Waziri, Hadiza Liman Mohammad, and Mohammed Abubakar Mohammed. "Partition behaviour of iron and zinc in the catchment alluvial sediments of River Gbako flood plains around Baddegi, central Bida basin, Nigeria." Scientia Bruneiana 18, no. 2 (May 27, 2020): 32–39. http://dx.doi.org/10.46537/scibru.v18i2.94.
Анотація:
Partition behaviors of iron (Fe) and zinc (Zn) were studied in the alluvial sediments of River Gbako floodplains around Baddegi using empirical formulas. The samples were cored from three pits locations (TR-1, TR-2, and TR-3). Particle size distribution and geochemical analysis were performed. Particle size distribution results indicated that the sediments are sand dominated. They have more than 50% sand with smaller percentages of clay and silt. Average partition coefficient values of Fe in the sediments are 1.02, 0.83, and 0.88 for TR-1, TR-2, and TR-3, respectively, and for Zn are 1.02, 0.95, and 0.83, for TR-1, TR-2 and TR-3, respectively. The average velocities of Fe mobilization in the sediments are 0.08 m/day, 0.07 m/day and 0.09 m/day for TR-1, TR-2 and TR-3, respectively, and for Zn mobilization are 0.07 m/day, 0.07 m/day and 0.09 m/day, for TR-1, TR-2, and TR-3, respectively. The metals were preferentially partitioned in the sediments than the water percolating through them, with average hydraulic conductivity (K) of 4.2 m/day. The partition behavior of the metals is used to explain contaminant transportation in the alluvial sediments of the River Gbako floodplains around Baddegi and the principle behind groundwater purification in the shallow alluvial aquifers of these floodplains.
Index Terms: Partition coefficient, hydraulic conductivity, alluvial sediments, floodplain, Nigeria
32
Babcsányi, Izabella, Margit Tamás, József Szatmári, Beáta Hambek-Oláh, and Andrea Farsang. "Assessing the impacts of the main river and anthropogenic use on the degree of metal contamination of oxbow lake sediments (Tisza River Valley, Hungary)." Journal of Soils and Sediments 20, no. 3 (December 4, 2019): 1662–75. http://dx.doi.org/10.1007/s11368-019-02516-y.
Анотація:
Abstract Purpose Oxbow lakes, reaches that were cut off from a river during river straightening works, can accumulate during flooding metal-rich suspended sediments transported by a river from mining-impacted source areas and other anthropogenic sources. Additionally, the anthropogenic use of oxbow lakes may significantly impact the sediment-bound metal concentrations. The aim was to determine the dominating effect in the sediments’ enrichment in heavy metals. Materials and methods We collected surface sediments (< 10-cm depth) from seven oxbow lakes once connected to the Tisza River (a transboundary river in Central and Eastern Europe). Four of the oxbows were located on the active floodplain, while three oxbows were at the reclaimed side (i.e., outside the flood defense levee). The sediment samples were subjected to total metal analyses (Cd, Co, Cr, Cu, Ni, Pb, and Zn) and sequential chemical extractions. Results and discussion Contamination indices (geoaccumulation index (Igeo) and pollution load index (PLI)) show a moderate but significant metal pollution of oxbow lakes situated on the active floodplain (Igeo (Pb) 0.95–1.25, PLI 2.1–2.8) and an overall unpolluted to slightly polluted status of those at the reclaimed side (Igeo (Pb) − 0.36–0.51, PLI 1.3–1.7). Additionally, the geochemical fractionation of the target metals showed that Cd and Zn were the most labile (Cd 29–48%, Zn 18–37% of non-residual proportions), indicating their environmental significance. Conclusions Canonical discriminant analysis of the sediment-bound metal concentrations revealed the prevalent role of the river connection over the anthropogenic use in controlling the metal enrichment of oxbow sediments.
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Kirchner, André, Jasmin Karaschewski, Philipp Schulte, Tina Wunderlich, and Tobias Lauer. "Latest Pleistocene and Holocene Floodplain Evolution in Central Europe—Insights from the Upper Unstrut Catchment (NW-Thuringia/Germany)." Geosciences 12, no. 8 (August 19, 2022): 310. http://dx.doi.org/10.3390/geosciences12080310.
Анотація:
The upper Unstrut River is located in Germany at the modern Central European climate boundary of Cfb and Dfb climate. The river drains a loess landscape, which has experienced important environmental changes throughout the last 12,000 years. To evaluate the impacts of these changes on floodplain evolution, a multi-proxy research program, consisting of 2D electrical resistivity tomography profiling (ERT), vibracoring, and sedimentological investigations, 14C and OSL dating were applied. From base to top the investigations the following fluvial deposits were revealed: (1) gravels embedded in a fine-grained sediment matrix (interpreted as fluvial bedload deposits); (2) silty sediment with pedogenic features (interpreted as overbank floodplain deposits); (3) peat and tufa deposits (interpreted as wetland deposits) intercalated by pedogenetically influenced silty sediments (interpreted as overbank deposits); (4) humic silty sediment with some pedogenic features (interpreted as overbank floodplain deposits); and (5) silty sediments (interpreted as overbank deposits). Radiocarbon and luminescence dates yielded the following periods for sediment formation: (1) Younger Dryas to Preboreal period (around 11.6 cal ka BP); (2) Preboreal to early Atlantic period (approx. 11.6 to 7.0 cal ka BP); (3) early Atlantic to late Subboreal period (approx. 7.3 to 3.4 cal ka BP); (4) late Subboreal to early Subatlantic period (2.9 to 2.3 cal ka BP); and (5) late Subatlantic period (approx. 1.0 to 0.6 cal ka BP). The results suggest that floodplain development during the latest Pleistocene and early Holocene (approx. 11.6 to 7.0 cal ka BP) was considerably controlled by climatic conditions and short-term climate variabilities, which caused gravel deposition and overbank sedimentation. Afterwards floodplain conditions varied between rather stable (peat and tufa development, initial soil formation) and active periods (deposition of overbank fines). In this context, active periods with increased sediment input prevailed from approx. 5.1 to 3.4 cal ka BP, 2.9 to 2.3 cal ka, and 1.0 to 0.6 cal ka BP, temporally corresponding well with increased land-use phases of the past. In conclusion this study demonstrates that the investigated Unstrut catchment has reacted very sensitively to natural and human-induced changes during the latest Pleistocene and Holocene. Consequently, this high vulnerability to external changes should be considered in future river predictions or river management.
34
Li, Zhen, Yoshiki Saito, Limi Mao, Toru Tamura, Zhen Li, Bing Song, Yulan Zhang, Anqing Lu, Sotham Sieng, and Jie Li. "Mid-Holocene mangrove succession and its response to sea-level change in the upper Mekong River delta, Cambodia." Quaternary Research 78, no. 2 (July 27, 2012): 386–99. http://dx.doi.org/10.1016/j.yqres.2012.07.001.
Анотація:
AbstractMiddle Holocene vegetation and mangrove successions are clearly evident in the palynological records of two cores from the upper Mekong River delta in Cambodia. Spanning from ~ 9.4 to 6.3 cal ka BP, the cores mainly record a transgressive sequence from floodplain freshwater marsh to tidal flat, which was overlain by mangrove. Corresponding to the decelerated sea-level rise at ~ 8.3 cal ka BP, pioneer mangrove species Sonneratia alba and Sonneratia caseolaris appeared in the sediments, and then was replaced by regressive mangrove succession containing upward-increasing abundances of Rhizophora apiculata and Bruguiera spp. High salinity- and flooding-tolerant community S. alba was developed at the western core site PSG at ~ 8.2 cal ka BP, and the eastern core site PK at ~ 7.5 cal ka BP. The time difference of S. alba appearance between the two sites might be resulted from the complexity of sedimentary environment, where a higher sediment supply was provided to the western floodplain than to the eastern floodplain. After 7.5 cal ka BP, aggradational stacking of intertidal sediments, of which the thickness is larger than the present maximum tidal range, may have resulted from continuous sea-level rise during 7.5–7.0 cal ka BP.
35
Popiuk, Yana, and Bohdan Ridush. "The structure of the lower terraces of the Dniester River valley (on the example of the Vasyliv-Doroshivtsi section)." Scientific Herald of Chernivtsi University. Geography, no. 824 (January 30, 2020): 64–72. http://dx.doi.org/10.31861/geo.2020.824.64-72.
Анотація:
The whole complex of terraces can be traced in the relief on the Vasyliv-Doroshivtsi area. Well-defined high terraces - XII (jr-kz), XI (bd-sv) and X (bv-br). The middle terraces in this area are narrow, poorly preserved in relief. The inner-canyon part of the Dniester valley is relatively wide, which contributed to the development and preservation of a full complex of lower (late Pleistocene) terraces: the fourth (kd-ts), third (pl-ud; fragmentary), second (vt-bg), first (df-pc) terraces, as well as Holocene high and low floodplains (hl). Researches of features of the structure of low terraces carried out on the basis of a survey of geomorphological surfaces, outcrops of terrace deposits, the analysis of boreholes, fossil vertebrate and mollusc faunas, and also results of long-term observations during archaeological researches of site Doroshivtsi 3. The first above-floodplain terrace (df-pc) is represented by small fragments. It is composed by channel facies of alluvium, represented mainly by pebbles. Above them the floodplain facies - fine- and medium-grained sand, light grey, obliquely and horizontally layered, are bedded. The floodplain alluvium is covered by a low-thickness stratum of loess-like loams (pc). To the west of Doroshivtsi Village, near the Hlynyshche site, the upper layer of sediments is partially destroyed and buried under the sediments of a high floodplain. Only the remains of the lower part of the section are partially present. That is, in this area, the roots of the first terrace serve as the base of the high floodplain. The second terrace (vt-bg) is most clearly manifested morphologically due to the ledge, which stands out quite clearly. It is better developed within the Vasyliv Village. Here it is quite extensive, its surface is planned. In the area of Doroshivtsi, this terrace is narrow, severely damaged, occurs in fragments. The basement of the terrace is located at the height of about 1 m above the current level of the Dniester River. It is composed of dark green-grey argillite and coarse-grained Devonian sandstones. The structure of the terrace is as follows: the channel facies (gravel-pebble deposits with inclusions of boulders and sand aggregate) and powerful floodplain facies of alluvium: rhythmic layers of sands, sands and loams with signs of embryonic soils); complex of fossil soils and forests (forest-like loams) - bg-pc. Numerous remains of molluscs, mega- and microfauna, remains of material culture were found in the terrace deposits (Doroshivtsi 3 site). The third terrace (pl-ud) is weakly expressed and narrow. There are no outcrops of its sediments here and no boreholes. Therefore, currently, its structure in the study area remains unknown. However, in the lower part of the sediments of this terrace during the digging of the well were found fragmented remains of a mammoth (Mammuthus sp.) and a red deer (Cervus elaphus) with traces of disposal (site Vasyliv II). At another location, a mammoth tooth was found, which we identified as Mammuthus primigenius cf. jatzkovi. Fourth terrace (kd-ts). Terrace sediments are exposed to the west of Vasyliv, also discovered by a borehole near the basement of the white-stone temple of the XII-XIII centuries. According to drilling data, the top of gravel here is at the height of 7 m above the boundary level of the Dniester River. Above the gravel are bedded (from bottom to top): a layer of chernozem-like paleosol (pl); the light yellow loess with a columnar structure (ud); brown paleosol (vt); the pale yellow, carbonate loess, with also a columnar structure (bg). According to the terraces' classification by their location in the river valley, low terraces in the study area of the Middle Dniester are incised. According to the genetic classification, they can be considered accumulative, closed- or hidden-socle. Thus, based on the row of data, the peculiarities of the structure of low terraces, the composition of sediments and their approximate geological age have been established. New sections of the second and fourth terraces are described based on the study of outcrops and drilling data. New locations of vertebrate and mollusc fauna have been discovered in the deposits of 2-4th terraces in the village of Vasyliv. The considerable width of the second floodplain terrace in the Vasyliv area in comparison with Doroshivtsi testifies to the prospects of finding here the remains of material culture, similar to the Doroshivtsi-3 site. As a result of research, we established that due to the different history and mechanism of sediment formation, the structure and composition of sediments of the same age terraces may differ. This fact should be considered when allocating terraces and rely not only on the features of the cover part of the sediments but on the set of characteristics of a terrace. The questions of the peculiarities of the fourth and first above-floodplain terraces' structure, as well as the depth of basement of the high floodplain, remain unclear.
36
Sarker, Shiblu. "Separation of Floodplain Flow and Bankfull Discharge: Application of 1D Momentum Equation Solver and MIKE 21C." CivilEng 4, no. 3 (August 21, 2023): 933–48. http://dx.doi.org/10.3390/civileng4030050.
Анотація:
A floodplain is an area of low-lying land adjacent to a river, stream, or other water body that is regularly inundated by water during periods of high flow. Floodplains typically have relatively flat terrain and are composed of sediments deposited by the river over time. Floodplain flow refers to the movement of water across the surface of the floodplain during periods of high flow. This flow can occur as a result of water spilling over the river banks or seeping into the ground and then re-emerging on the surface of the floodplain. Bankfull discharge is the flow of water that just fills the channel of a river or stream to the top of its banks. It is the point at which the river or stream is at its maximum capacity without overflowing onto the floodplain. Bankfull discharge is often used as a reference point for assessing flood risk and planning floodplain management strategies. To examine the bank-to-bank hydro-morphodynamics of a river, it is necessary to comprehend the flow distribution throughout the main stream and floodplain. Along with river hydraulics, bankfull discharge is a crucial parameter for estimating river bank erosion. For evaluating the distribution and generation of river flow over the floodplain and main stream, a variety of modeling tools and approaches are available. This study investigates methods for separating floodplain flow and bankfull discharge from observed discharge data using the one-dimensional momentum equation. A two-dimensional modeling tool (MIKE 21C) was also employed to investigate the usefulness of the proposed method in a region with an enormous floodplain.
37
Szabó, Zsuzsanna, Botond Buró, József Szabó, Csaba Albert Tóth, Edina Baranyai, Petra Herman, József Prokisch, Tamás Tomor, and Szilárd Szabó. "Geomorphology as a Driver of Heavy Metal Accumulation Patterns in a Floodplain." Water 12, no. 2 (February 18, 2020): 563. http://dx.doi.org/10.3390/w12020563.
Анотація:
The spatial complexity of floodplains is a function of several processes: hydrodynamics, flow direction, sediment transportation, and land use. Sediments can bind toxic elements, and as there are several pollution sources, the risk of heavy metal accumulation on the floodplains is high. We aimed to determine whether fluvial forms have a role in metal accumulations. Topsoil samples were taken from point bars and swales in the floodplain of the Tisza River, North-East Hungary. Soil properties and metal concentrations were determined, and correlation and hypothesis testing were applied. The results showed that fluvial forms are important drivers of horizontal metal patterns: there were significant differences (p < 0.05) between point bars and swales regarding Fe, K, Mg, Mn, Cr, Cu, Ni, Pb, and Zn. Vertical distribution also differed significantly by fluvial forms: swales had higher metal concentrations in all layers. General Linear Models had different results for macro and micro elements: macro element concentrations were determined by the organic matter, while for micro elements the clay content and the forms were significant explanatory variables. These findings are important for land managers and farmers because heavy metal concentration has a direct impact on living organisms, and the risk of bioaccumulation can be high on floodplains.
38
Goncalves, Vinicius Verona Carvalho, Therezinha de Jesus Pinto Fraxe, Jaisson Miyosi Oka, Mônica Suani Barbosa da Costa, Janderlin Patrick Rodrigues Carneiro, Gislany Mendonça de Sena, Andreza de Souza Lopes, and Antônio Carlos Witkoski. "Use of resources in lowland areas in the Amazon and Sustainable Development: Paradigm changes with the advent of modernity." Research, Society and Development 11, no. 12 (September 23, 2022): e527111232348. http://dx.doi.org/10.33448/rsd-v11i12.32348.
Анотація:
The floodplain areas comprise the floodplains influenced by white water rivers, rich in sediments. The beginning of the process of occupation of floodplain areas in the Amazon is strongly debated by scholars and researchers. Some authors point out that the occupations occurred in a diffuse way in the Amazon, predominating in two large environments in the Amazon, the terra firme forests and the forests in floodplain areas. These characteristics boosted four main economic activities in the floodplain: fishing, forestry, agriculture and livestock. These activities were, for a long time, practiced by indigenous people and soon followed by caboclos-ribeirinhos, respecting the limits of nature and its carrying capacity. However, over the years and with the advent of modernity, it has not only projected the growth of man, and his reason, but has also increased the exploitation of natural resources used by man. Fishing resources such as arapaima, manatees and turtles, in addition to multispecific fishing, acquired another character with the arrival of the Portuguese, which persists to this day. In this way, it is clear how these resources are becoming scarce due to irrational use and above all marketing.
39
Gontijo, Júlia B., Fabiana S. Paula, Andressa M. Venturini, Jéssica A. Mandro, Paul L. E. Bodelier, and Siu M. Tsai. "Insights into the Genomic Potential of a Methylocystis sp. from Amazonian Floodplain Sediments." Microorganisms 10, no. 9 (August 30, 2022): 1747. http://dx.doi.org/10.3390/microorganisms10091747.
Анотація:
Although floodplains are recognized as important sources of methane (CH4) in the Amazon basin, little is known about the role of methanotrophs in mitigating CH4 emissions in these ecosystems. Our previous data reported the genus Methylocystis as one of the most abundant methanotrophs in these floodplain sediments. However, information on the functional potential and life strategies of these organisms living under seasonal flooding is still missing. Here, we described the first metagenome-assembled genome (MAG) of a Methylocystis sp. recovered from Amazonian floodplains sediments, and we explored its functional potential and ecological traits through phylogenomic, functional annotation, and pan-genomic approaches. Both phylogenomics and pan-genomics identified the closest placement of the bin.170_fp as Methylocystis parvus. As expected for Type II methanotrophs, the Core cluster from the pan-genome comprised genes for CH4 oxidation and formaldehyde assimilation through the serine pathway. Furthermore, the complete set of genes related to nitrogen fixation is also present in the Core. Interestingly, the MAG singleton cluster revealed the presence of unique genes related to nitrogen metabolism and cell motility. The study sheds light on the genomic characteristics of a dominant, but as yet unexplored methanotroph from the Amazonian floodplains. By exploring the genomic potential related to resource utilization and motility capability, we expanded our knowledge on the niche breadth of these dominant methanotrophs in the Amazonian floodplains.
40
Brown, Antony G., and Keith E. Barber. "Late Holocene Paleoecology and Sedimentary History of a Small Lowland Catchment in Central England." Quaternary Research 24, no. 1 (July 1985): 87–102. http://dx.doi.org/10.1016/0033-5894(85)90085-7.
Анотація:
A variety of paleoecological and sedimentary techniques were used to investigate the storage of sediment within a small lowland catchment during the Holocene. Radiocarbon dating of vertically accreted floodplain deposits allowed the calculation of inorganic accumulation rates. These rates show a dramatic increase in sediment deposition during the late Bronze Age and early Iron Age (2900-2300 yr B.P.) due to deforestation and cultivation of the catchment slopes and resultant soil erosion. The soils within the catchment were susceptible to structural damage, surface waterlogging, and slope-wash erosion. From the calculated increases in sediment storage estimates of catchment erosion were made which vary from around 20 to 140 tons km−2 yr−1. The study of alluvial chronology at this scale can provide unique information on the source areas of Holocene floodplain sediments and provide long-term erosion rates.
41
DAMIAN, Gheorghe, Gheorghe IEPURE, Daniel NASUI, Gyozo JORDAN, Jasminka ALIJAGIC, Danijel IVANIŠEVIĆ, Lidija GALOVIĆ, and Ioan BERES. "ASSESSMENT OF RIVER SEDIMENT QUALITY ACCORDING TO THE EU WATER FRAMEWORK DIRECTIVE IN MOUNTAINOUS FLUVIAL CONDITIONS. A CASE STUDY IN THE UPPER TISA AREA, DANUBE RIVER BASIN." Carpathian Journal of Earth and Environmental Sciences 17, no. 2 (August 31, 2022): 441–58. http://dx.doi.org/10.26471/cjees/2022/017/234.
Анотація:
Discharge of hazardous substances (HSs) in hydrographic basins represent a danger to aquatic biological activity and water supplies and can severely pollute surface water sediments. The increase of pollution in the Danube Basin requires the implementation of systematic monitoring and evaluation of the sediments quality as dictated by the EU Water Framework Directive. For this system development, applicable in mountainous conditions, the Upper Tisa region in the northwest part of Romania on the border with Ukraine, Hungary and Slovakia was selected as a test area. Sampling of overbank (floodplain) sediment, river bottom sediment and suspended sediment was carried out at 10 locations in the test area in order to analyze the concentration and distribution of eight metal(oid)s (Cu, Pb, Zn, Cd, Hg, Ni, Cr and As), in addition to 3 organic components (anthracene, fluoranthene, benzo(e)pyrene) as hazardous substances (HSs). The sediment quality assessment was carried out according to the 2013/39/EU Directive and EU Water Framework Directive standards. Most of the analyzed HS concentrations in river bottom sediment and overbank (floodplain) sediments fall within the limits of environmental quality standards (EQS). As, Cu, Pb, and Zn tend to exceed the EQS at some locations. The highest exceedances were recorded for Pb, for which contents of up to 987 mg/kg were detected. The highest contents were found in the overbank sediments sampled, and the lowest in river bottom sediments, which may indicate historical pollution. Mercury contents in overbank sediment samples exceed all standards, while cadmium content is below the international standards. Anthracene, fluoranthene and benzo(e)pyrene concentrations in overbank and bottom sediments comply with international standards. A few samples in suspended sediments slightly exceed the lowest environmental standard value (i.e., Romanian normal value). HS concentrations remain low in the suspended sediments showing that it is not the main transport route for pollution in this area. HS contents decrease gradually from upstream to downstream due to dilution along the river course. In the last testing point at Someș Aciua, the concentration of metal(oid)s measured in the sediments remain below the EQS limit values, thus there is no risk of transboundary pollution. The main source of metal(oid) contamination is historic base-metal ore mining and the associated mine waste sites in the Baia Mare and other mining areas scattered around the whole region. The main source of the studied organic compounds is the incomplete or low-temperature coal combustion processes that occur in households in rural areas
42
Dubar, Michel, and Edward J. Anthony. "Holocene Environmental Change and River-Mouth Sedimentation in the Baie des Anges, French Riviera." Quaternary Research 43, no. 3 (May 1995): 329–43. http://dx.doi.org/10.1006/qres.1995.1039.
Анотація:
AbstractRiver mouths on the steep, high-relief coast of the French Riviera exhibit thick sequences of Holocene marine, estuarine, deltaic, and river channel-floodplain sediments that overlie basal fluvial Pleistocene gravel. Gravel is uncommon in most of the early to middle Holocene aggradational-progradational marine, estuarine, deltaic sediments, despite an ample supply from rock units in the steep adjoining uplands. River-mouth gravel is common only in late Holocene river channels and in barrier beaches perched on finer-grained nearshore sediments. Neither downslope grain-size fining on alluvial fans nor sediment stacking patterns during sea-level (base-level) rise readily account for the lack of early to middle Holocene gravel in the river-mouth sediment wedges. Holocene sea-level rise led to the storage of fine-grained sediments in shallow marine, estuarine, and deltaic environments in the present coastal zone. We infer that humid temperate conditions, a dense forest cover, landscape stabilization, and a regular quiescent river flow regime associated with the Atlantic climatic optimum limited gravel supply in the adjoining catchments and gravel entrainment downstream during the early Holocene. Sea-level stabilization in the middle and late Holocene coincided with a marked change in bioclimatic conditions toward the present Mediterranean-type regime, which is characterized by a less dense forest cover, soil erosion, and episodic catastrophic floods. The late Holocene was thus a time of downstream bedload channel aggradation, fine-grained floodplain and paludal sedimentation, and seaward flushing of clasts leading to the formation and consolidation of the gravel barrier beaches that bound the rivermouths and embayments.
43
Degembaeva, N. K., N. Y. Ismailov, E. M. Baibagyshov, G. J. Orozalieva, and B. Z. Abidinov. "GEOMORPHOLOGICAL STRUCTURES OF THE FLOODPLAIN AREAS OF THE NARYN RIVER (KYRGYZSTAN)." Herald of KSUCTA n a N Isanov, no. 2-2-2022 (April 30, 2022): 610–19. http://dx.doi.org/10.35803/1694-5298.2022.2.610-619.
Анотація:
The ecological state of floodplains is estimated by a high number of different structural units. This is important for ensuring the ecological function and increasing the sustainability of river ecosystems. The impact of land use change on fluvial and hydrological changes in the floodplain and its terraced surface is important for understanding current geomorphological processes. The increase in roughness and the accumulation of sediments on the surface of the floodplain is favorable for the uniform distribution of the river flow. To study the dynamics of changes in the riverbed, study sites were selected far and near settlements, using the example of the village of Emgek-Talaa and Ak-Tal in the Naryn region of Kyrgyzstan. To study changes in the landscape, satellite images were used to map the study areas. Assessment of changes is necessary for the further development of the restoration plan for the structure of floodplain rivers. The results of the study will provide information on management options and assist local authorities in the integrated management of natural resources.
44
Mendoza, Rosendo, Julián Martínez, Javier Rey, M. Carmen Hidalgo, and M. José Campos-Suñol. "Metal(loid)s Transport in Hydrographic Networks of Mining Basins: The Case of the La Carolina Mining District (Southeast Spain)." Geosciences 10, no. 10 (September 28, 2020): 391. http://dx.doi.org/10.3390/geosciences10100391.
Анотація:
This study analyses the distribution of the total metal(loid)s content accumulated in the sediments of the Grande River, the most important river course that runs through the old mining district of La Carolina (Jaén, Spain), whose waters are collected in an urban supply reservoir. In total, 102 sediments samples were taken along the river, 51 in the live-bed channel and another 51 in the floodplain. The samples analysed have high metal(loid)s content, sometimes much higher than the reference levels established by European and regional legislation for soils, especially Pb, As and Ba, with average values of 5452 mg/kg, 116 mg/kg and 2622 mg/kg, respectively. The statistical analysis of the values obtained allows the distribution of the contents of the different elements along the river to be characterized and the associations and dispersion patterns in the sediments of the metal(loid)s coming from the environmental liabilities of the numerous dumpsites and tailings dams generated by mining activity to be defined. In both cases, the high metal(loid)s content identified as well as the resulting values of various environmental indices (the enrichment factor, contamination factor, geoaccumulation index, potential ecological risk index and pollution load index), confirmed that the sediment samples were moderately to highly contaminated over extensive areas of the basin studied, with the greatest intensity and extent in the floodplain sediments.
45
von Suchodoletz, Hans, Christiane Richter, Frank Walther, Marcel Bliedtner, Mariam Eloshvili, Levan Losaberidze, and Bernhard Hausdorf. "Snail assemblages in Holocene floodplain research – an example from the southern Caucasus." E&G Quaternary Science Journal 69, no. 2 (December 14, 2020): 247–60. http://dx.doi.org/10.5194/egqsj-69-247-2020.
Анотація:
Abstract. During the last decades, rivers and their deposits in different regions were intensively studied to better understand the late-Quaternary landscape evolution and former human activities. One proxy for paleoecological and paleoclimatic reconstructions is the analysis of gastropods (snails) from carbonatic river sediments. In the scope of this study, we investigated gastropod assemblages from a Holocene fluvial sediment–paleosol sequence at the upper Alazani River in the southeastern Caucasus. On the one hand, we aimed to derive reliable independent information about possible long-lasting human activity since the late Neolithic–Chalcolithic in the upper Alazani floodplain. This was formerly suggested by n-alkane biomarker vegetation reconstructions from the fluvial sediments. However, the reliability of that method is still debated. On the other hand, we aimed to obtain reliable information about a formerly suggested, possibly tectonic-driven, large-scale shift of the river course during the Late Holocene. In agreement with the n-alkane biomarkers, our results demonstrate that the studied site was free of the natural forests during the Early and Middle Holocene until ca. 4.5 cal kyr BP. Since this contrasts with a pollen-based vegetation reconstruction from a neighboring floodplain that was covered with forests during that time, the open vegetation in the upper Alazani valley was probably caused by continuous settlement activity as is also indicated by archeological finds in the sequence. Therefore, using our paleoecological proxies it is possible that we identified a settlement center in the upper Alazani floodplain that was populated from the late Neolithic–Chalcolithic. This center was not known thus far, since the settlement remains are covered by thick floodloam today that hindered their detection during archeological surface surveys. Therefore, our findings suggest that the area in the southern Caucasus region that was settled during the late-Neolithic–Chalcolithic period should have been larger than was known thus far. Furthermore, increasing contributions of wetland gastropods since ca. 4 cal kyr BP confirm a local shift of the river course towards the investigated site during the Late Holocene, possibly linked with ongoing tectonic activity. However, in contrast to former suggestions our gastropod assemblages indicate a slow rather than abrupt process. Our study demonstrates the high value of gastropod assemblages for geoarcheological and geomorphological research in floodplains with carbonatic river sediments at both a regional and local spatial scale.
46
Marinho, Rogério Ribeiro, Antonio Fábio Sabbá Guimarães Vieira, and Feliciano De Souza Maciel. "Análise Montante-Jusante da Granulometria dos Sedimentos de Fundo e Suspenso do Rio Negro e Tributários (Bacia Amazônica, Brasil)." Revista Brasileira de Geografia Física 14, no. 2 (April 14, 2021): 997. http://dx.doi.org/10.26848/rbgf.v14.2.p997-1008.
Анотація:
O conhecimento das características físicas de sedimentos transportados por grandes sistemas fluviais possui significativa importância para o entendimento de processos geomorfológicos e hidrológicos. O nível de conhecimento dos grandes sistemas fluviais da Amazônia e sua relação com o transporte de sedimentos ainda é limitado, resultando em lacunas de conhecimento sobre a dinâmica da paisagem nesta complexa região. Este trabalho teve como objetivo avaliar a distribuição espacial da granulometria de sedimentos de fundo e suspenso do Rio Negro e tributários. Realizou-se análise da distribuição do tamanho dos sedimentos em seções amostrais localizadas no alto, médio e baixo curso do Rio Negro. Os resultados da análise granulométrica da carga de fundo indicam a predominância de sedimentos com tamanho variando de 0,25 a 1,0 mm (principalmente areia fina, areia média e areia grossa) enquanto no baixo curso as amostram oscilaram de areia fina a partículas lamosas (< 0,50 mm). No Rio Negro os sedimentos suspensos são compostos principalmente de partículas finas de silte (90% menor que 80 µm) com diâmetro mediano (D50) de 25 µm. As características granulométricas apresentadas neste trabalho fornecem subsídios para o entendimento de processos hidrodinâmicos de transporte e deposição dos sedimentos de fundo e suspenso neste gigante sistema fluvial. Upstream-downstream Granulometry Analysis of bed and suspended sediments in the Negro River Basin (Amazon Basin, Brazil)A B S T R A C TThe knowledge of the physical characteristics of sediments transported by large river systems has significant importance for the understanding of geomorphological and hydrological processes. The level of knowledge of the large rivers of the Amazon basin and their relationship with sediment transport is limited, resulting in gaps about the dynamics of the landscape in this complex region. This article analyzes the spatial distribution of granulometry of bed and suspended sediments in the Negro River and tributaries. An analysis of the sediment size distribution was carried out in sample sections located in the upper, middle and lower reaches of the Negro River. The results of the granulometric analysis of the bed load indicate the predominance of sediments with sizes ranging from 0.25 to 1.0 mm (mainly fine sand, medium sand and coarse sand) while in the low course they showed oscillated from fine sand to muddy particles (<0.50 mm). In the Negro River basin the suspended sediments are composed mainly of fine silt particles (90% less than 80 µm) with a median diameter (D50) of 25 µm. The granulometric characteristics presented in this work provide subsidies for the understanding of hydrodynamic processes of transport and deposition of bed and suspended sediments in this huge fluvial system.Keywords: sediment transport, Amazon floodplain, multichannel river, anabranching
47
Sviridova, L. L., and A. P. Glinushkin. "SAPROPELIC SEDIMENTS OF THE VOLGA-AKHTUBA FLOODPLAIN." IOP Conference Series: Earth and Environmental Science 663, no. 1 (February 1, 2021): 012056. http://dx.doi.org/10.1088/1755-1315/663/1/012056.
48
Hostache, R., C. Hissler, P. Matgen, C. Guignard, and P. Bates. "Modelling suspended-sediment propagation and related heavy metal contamination in floodplains: a parameter sensitivity analysis." Hydrology and Earth System Sciences 18, no. 9 (September 10, 2014): 3539–51. http://dx.doi.org/10.5194/hess-18-3539-2014.
Анотація:
Abstract. Fine sediments represent an important vector of pollutant diffusion in rivers. When deposited in floodplains and riverbeds, they can be responsible for soil pollution. In this context, this paper proposes a modelling exercise aimed at predicting transport and diffusion of fine sediments and dissolved pollutants. The model is based upon the Telemac hydro-informatic system (dynamical coupling Telemac-2D-Sysiphe). As empirical and semiempirical parameters need to be calibrated for such a modelling exercise, a sensitivity analysis is proposed. An innovative point in this study is the assessment of the usefulness of dissolved trace metal contamination information for model calibration. Moreover, for supporting the modelling exercise, an extensive database was set up during two flood events. It includes water surface elevation records, discharge measurements and geochemistry data such as time series of dissolved/particulate contaminants and suspended-sediment concentrations. The most sensitive parameters were found to be the hydraulic friction coefficients and the sediment particle settling velocity in water. It was also found that model calibration did not benefit from dissolved trace metal contamination information. Using the two monitored hydrological events as calibration and validation, it was found that the model is able to satisfyingly predict suspended sediment and dissolve pollutant transport in the river channel. In addition, a qualitative comparison between simulated sediment deposition in the floodplain and a soil contamination map shows that the preferential zones for deposition identified by the model are realistic.
49
Watson, F. T., R. J. Smernik, A. L. Doolette, and L. M. Mosley. "Phosphorus speciation and dynamics in river sediments, floodplain soils and leaf litter from the Lower Murray River region." Marine and Freshwater Research 70, no. 11 (2019): 1522. http://dx.doi.org/10.1071/mf18360.
Анотація:
Phosphorus (P) availability, which depends on both P concentration and speciation, often controls primary productivity and algal-bloom formation in river systems. The river P pool is also connected to P pools of adjacent sediments, soils and vegetation. Thus, informed management of P in floodplain–river systems requires detailed understanding of P concentration and speciation in all of these interconnected components. We studied P speciation in river sediments and water, floodplain soils and river red gum (Eucalyptus camaldulensis) leaf litter from the Lower Murray region using conventional spectroscopic measurements, solution 31P nuclear magnetic resonance (31P NMR) spectroscopy, and leaching experiments to simulate floodplain re-wetting of leaf litter. Almost all (>85%) of the P in river sediments was in the orthophosphate form, whereas floodplain soils had higher proportions of organic P (PO) species. Both fresh and senescent river red gum leaf litter also had a much higher concentration of PO, primarily in the form of phytate. On submersion, there was a rapid (0–96h) loss of dissolved P from senescent leaves; release of dissolved organic carbon showed similar kinetics. Loss of P from the leaves included both organic and inorganic forms. The results have important implications for aquatic primary productivity and environmental management strategies.
50
Naimo, Teresa J., James G. Wiener, W. Gregory Cope, and Nicolas S. Bloom. "Bioavailability of sediment-associated mercury toHexageniamayflies in a contaminated floodplain river." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 5 (May 1, 2000): 1092–102. http://dx.doi.org/10.1139/f00-043.
Анотація:
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 (ΣHg) ranged from 880 to 22 059 ng·g dry weight-1in contaminated sediments and from 90 to 272 ng·g-1in 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 ΣHg 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.