Lacy, Jessica; Ferner, Matthew C.; Callaway, John C.
2018-01-01
Sediment flux in marsh tidal creeks is commonly used to gage sediment supply to marshes. We conducted a field investigation of temporal variability in sediment flux in tidal creeks in the accreting tidal marsh at China Camp State Park adjacent to northern San Francisco Bay. Suspended-sediment concentration (SSC), velocity, and depth were measured near the mouths of two tidal creeks during three six-to-ten-week deployments: two in winter and one in summer. Currents, wave properties and SSC were measured in the adjacent shallows. All deployments spanned the largest spring tides of the season. Results show that tidally-averaged suspended-sediment flux (SSF) in the tidal creeks decreased with increasing tidal energy, and SSF was negative (bayward) for tidal cycles with maximum water surface elevation above the marsh plain. Export during the largest spring tides dominated the cumulative SSF measured during the deployments. During ebb tides following the highest tides, velocities exceeded 1 m/s in the narrow tidal creeks, resulting in negative tidally-averaged water flux, and mobilizing sediment from the creek banks or bed. Storm surge also produced negative SSF. Tidally-averaged SSF was positive in wavey conditions with moderate tides. Spring-tide sediment export was about 50% less at a station 130 m further up the tidal creek than at the creek mouth. The negative tidally-averaged water flux near the creek mouth during spring tides indicates that in the lower marsh, some of the water flooding directly across the bay--marsh interface drains through the tidal creeks, and suggests that this interface may be a pathway for sediment supply to the lower marsh as well.
Tidal Creek Morphology and Sediment Type Influence Spatial Trends in Salt Marsh Vegetation
DEFF Research Database (Denmark)
Kim, Daehyun; Cairns, David M.; Bartholdy, Jesper
2013-01-01
that by shaping major geomorphic features and providing sediments to the adjacent sites, fluvial-geomorphic processes of tidal creeks exert fundamental controls on the cross-channel distribution of abiotic and biotic factors. These results point to a need for biogeomorphic and landscape ecological perspectives...
Rapid evolution of a marsh tidal creek network in response to sea level rise.
Hughes, Z. J.; Fitzgerald, D. M.; Mahadevan, A.; Wilson, C. A.; Pennings, S. C.
2008-12-01
In the Santee River Delta (SRD), South Carolina, tidal creeks are extending rapidly onto the marsh platform. A time-series of aerial photographs establishes that these channels were initiated in the 1950's and are headward eroding at a rate of 1.9 m /yr. Short-term trends in sea level show an average relative sea level rise (RSLR) of 4.6 mm/yr over a 20-year tide gauge record from nearby Winyah Bay and Charleston Harbor (1975-1995). Longer-term (85-year) records in Charleston suggest a rate of 3.2 mm/yr. RSLR in the SRD is likely even higher as sediment cores reveal that the marsh is predominantly composed of fine-grained sediment, making it highly susceptible to compaction and subsidence. Furthermore, loss in elevation will have been exacerbated by the decrease in sediment supply due to the damming of the Santee River in 1939. The rapid rate of headward erosion indicates that the marsh platform is in disequilibrium; unable to keep pace with RSLR through accretionary processes and responding to an increased volume and frequency of inundation through the extension of the drainage network. The observed tidal creeks show no sinuosity and a distinctive morphology associated with their young age and biological mediation during their evolution. Feedbacks between tidal flow, vegetation and infauna play a strong role in the morphological development of the creeks. The creek heads are characterized by a region denuded of vegetation, the edges of which are densely populated and burrowed by Uca Pugnax (fiddler crab). Crab burrowing destabilizes sediment, destroys rooting and impacts drainage. Measured infiltration rates are three orders of magnitude higher in the burrowed regions than in a control area (1000 ml/min and 0.6 ml/min respectively). Infiltration of oxygenated water enhances decomposition of organic matter and root biomass is reduced within the creek head (marsh=4.3 kg/m3, head=0.6 kg/m3). These processes lead to the removal and collapse of the soils, producing
Poirier, E.; van Proosdij, D.; Milligan, T. G.
2017-12-01
Seasonal variability in the sediment dynamics of a Bay of Fundy tidal creek and salt marsh system was analyzed to better understand the ecomorphodynamics of a high suspended sediment concentration intertidal habitat. Data were collected over 62 tides for velocity, suspended sediment concentration, deposition, and grain size at four stations from the creek thalweg to the marsh surface. Five topographic surveys were also conducted throughout the 14-month study. Deposition rates per tide varied spatially from 56.4 g·m-2 at the creek thalweg to 15.3 g·m-2 at the marsh surface. Seasonal variations in deposition in the creek and marsh surface were from 38.0 g·m-2 to 97.7 g·m-2 and from 12.2 g·m-2 to 19.6 g·m-2 respectively. Deposition and erosion were greatest in late fall and winter. This seasonal change, led by higher suspended sediment concentrations, was observed in the creek and at the marsh bank but notably absent from the marsh edge and marsh surface. Sediments were predominantly deposited in floc form (76-83%). Because of high floc content, higher suspended sediment concentrations led to more rapid loss of sediment from suspension. With increasing sediment concentration, deposition increased in the tidal creek and at the marsh bank but not at the marsh edge or marsh surface. This suggests that in highly flocculated environments the water column clears fast enough that very little sediment remains in suspension when the water reaches the marsh and that the sediment concentration during marsh inundation is independent of the initial concentration in the creek.
Temmerman, S.; Bouma, T.J.; Govers, G.; Lauwaet, D.
2005-01-01
This study provides new insights in the relative role of tidal creeks and the marsh edge in supplying water and sediments to and from tidal marshes for a wide range of tidal inundation cycles with different high water levels and for marsh zones of different developmental stage. Net import or export
Suspended-sediment trapping in the tidal reach of an estuarine tributary channel
Downing-Kunz, Maureen; Schoellhamer, David H.
2015-01-01
Evidence of decreasing sediment supply to estuaries and coastal oceans worldwide illustrates the need for accurate and updated estimates. In the San Francisco Estuary (Estuary), recent research suggests a decrease in supply from its largest tributaries, implying the increasing role of smaller, local tributaries in sediment supply to this estuary. Common techniques for estimating supply from tributaries are based on gages located above head of tide, which do not account for trapping processes within the tidal reach. We investigated the effect of a tidal reach on suspended-sediment discharge for Corte Madera Creek, a small tributary of the Estuary. Discharge of water (Q) and suspended-sediment (SSD) were observed for 3 years at two locations along the creek: upstream of tidal influence and at the mouth. Comparison of upstream and mouth gages showed nearly 50 % trapping of upstream SSD input within the tidal reach over this period. At the storm time scale, suspended-sediment trapping efficiency varied greatly (range −31 to 93 %); storms were classified as low- or high-yield based on upstream SSD. As upstream peak Q increased, high-yield storms exhibited significantly decreased trapping. Tidal conditions at the mouth—ebb duration and peak ebb velocity—during storms had a minor effect on sediment trapping, suggesting fluvial processes dominate. Comparison of characteristic fluvial and tidal discharges at the storm time scale demonstrated longitudinal differences in the regulating process for SSD. These results suggest that SSD from gages situated above head of tide overestimate sediment supply to the open waters beyond tributary mouths and thus trapping processes within the tidal reach should be considered.
Tidal mixing in Dahej creek waters
Digital Repository Service at National Institute of Oceanography (India)
Swamy, G.N.; Sarma, R.V.
Mixing characteristics of a tidal inlet near Dahej at the mouth of Narmada River, Gujarat, India are examined in terms of tides, currents and bathymetry. The dilution potential of the Dahej Creek waters during a tidal march for a given rate...
Tidal Creek Sentinel Habitat Database
National Oceanic and Atmospheric Administration, Department of Commerce — The Ecological Research, Assessment and Prediction's Tidal Creeks: Sentinel Habitat Database was developed to support the National Oceanic and Atmospheric...
Effects of causeway construction on vegetation and sedimentation in North Carolina tidal marshes
Knowlton, A.; Leonard, L.; Pricope, N. G.; Eulie, D.
2017-12-01
Causeways, especially those constructed to facilitate transportation across low lying tidal marshes, are known to affect tidal exchanges and thereby potentially influence geological and biological processes in these ecosystems. While these impacts have been documented in several expansive marsh systems with large tidal ranges, the extent of these impacts in smaller tidal creek watersheds is less understood. This study examined how the presence, absence, and removal of small causeways affected sedimentological processes and vegetation characteristics in two small tidal creek watersheds in Wilmington, NC. Surficial deposition rates, determined using petri-dish sediment traps, indicate that mean deposition landward of a small causeway (1.64 mg cm-2day-1) is significantly lower (pchanges adjacent to the causeway. Partial causeway removal in one of these systems in 2006 also provided the opportunity to evaluate how the marsh canopy responded to causeway removal. Using Juncus roemerianus and Spartina alterniflora as a proxy for changes in tidal exchange, spectroradiometer data and aerial imagery available in 2006 and 2016 will be used to quantify changes in canopy coverage subsequent to causeway removal. Although this study is ongoing, the preliminary results indicate that small causeways, similar to their larger counterparts, significantly affect the rate and characteristics of sediment delivered to landward marshes and also affect tidal exchanges that lead to changes in vegetation characteristics.
Diel variation in fish assemblages in tidal creeks in southern Brazil
Directory of Open Access Journals (Sweden)
JF. Oliveira-Neto
Full Text Available Tidal creeks are strongly influenced by tides and are therefore exposed to large differences in salinity and depth daily. Here we compare fish assemblages in tidal creeks between day and night in two tidal creeks in southern Brazil. Monthly day and night, simultaneous collections were carried out in both creeks using fyke nets. Clupeiformes tended to be caught more during the day. Cathorops spixii, Genidens genidens and Rypticus randalli tended to be caught at night. Sciaenidae also tended to be caught more during the night. In general, pelagic species were diurnal, while deep water species were nocturnal. These trends are probably due to a variety of causes, such as phylogeny, predation and net avoidance.
Tidal flow characteristics at Kasheli (Kalwa/ Bassein creek), Bombay
Digital Repository Service at National Institute of Oceanography (India)
Swamy, G.N.; Suryanarayana, A.
Tidal flow characteristics of waters at Kasheli, connected to the sea through Thane and Bassein Creeks in Bombay, Maharashtra, India are investigated based on tide and current observations carried out in 1980-81. The results establish that the tidal...
On luminescence bleaching of tidal channel sediments
DEFF Research Database (Denmark)
Fruergaard, Mikkel; Pejrup, Morten; Murray, Andrew S.
2015-01-01
We investigate the processes responsible for bleaching of the quartz OSL signal from tidal channel sediment. Tidal dynamics are expected to play an important role for complete bleaching of tidal sediments. However, no studies have examined the amount of reworking occurring in tidal channels...... and on tidal flats due to the mixing caused by currents and waves. We apply bed level data to evaluate the amount of vertical sediment reworking in modern tidal channels and at a tidal flat. Cycles of deposition and erosion are measured with a bed level sensor, and the results show that gross sedimentation...... was several times higher than net sedimentation. We propose that tidal channel sediment is bleached either on the tidal flat before it is transported to the tidal channels and incorporated in channel-fill successions or, alternatively, on the shallow intertidal part of the channel banks. Based...
Seasonal variations in suspended-sediment dynamics in the tidal reach of an estuarine tributary
Downing-Kunz, Maureen A.; Schoellhamer, David H.
2013-01-01
Quantifying sediment supply from estuarine tributaries is an important component of developing a sediment budget, and common techniques for estimating supply are based on gages located above tidal influence. However, tidal interactions near tributary mouths can affect the magnitude and direction of sediment supply to the open waters of the estuary. We investigated suspended-sediment dynamics in the tidal reach of Corte Madera Creek, an estuarine tributary of San Francisco Bay, using moored acoustic and optical instruments. Flux of both water and suspended-sediment were calculated from observed water velocity and turbidity for two periods in each of wet and dry seasons during 2010. During wet periods, net suspended-sediment flux was seaward; tidally filtered flux was dominated by the advective component. In contrast, during dry periods, net flux was landward; tidally filtered flux was dominated by the dispersive component. The mechanisms generating this landward flux varied; during summer we attributed wind–wave resuspension in the estuary and subsequent transport on flood tides, whereas during autumn we attributed increased spring tide flood velocity magnitude leading to local resuspension. A quadrant analysis similar to that employed in turbulence studies was developed to summarize flux time series by quantifying the relative importance of sediment transport events. These events are categorized by the direction of velocity (flood vs. ebb) and the magnitude of concentration relative to tidally averaged conditions (relatively turbid vs. relatively clear). During wet periods, suspended-sediment flux was greatest in magnitude during relatively turbid ebbs, whereas during dry periods it was greatest in magnitude during relatively turbid floods. A conceptual model was developed to generalize seasonal differences in suspended-sediment dynamics; model application to this study demonstrated the importance of few, relatively large events on net suspended-sediment flux
White, S. M.; Madsen, E.
2013-12-01
Inundation of marsh surfaces by tidal creek flooding has implications for the headward erosion of salt marsh creeks, effect of rising sea levels, biological zonation, and marsh ecosystem services. The hydroperiod; as the frequency, duration, depth and flux of water across the marsh surface; is a key factor in salt marsh ecology, but remains poorly understood due to lack of data at spatial scales relevant to tracking the spatial movement of water across the marsh. This study examines how hydroperiod, drainage networks, and tidal creek geomorphology on the vegetation at Crab Haul Creek. Crab Haul Creek is the farthest landward tidal basin in North Inlet, a bar-built estuary in South Carolina. This study measures the hydroperiod in the headwaters Crab Haul Creek with normal and near-IR photos from a helium balloon Helikite at 75-100 m altitude. Photos provide detail necessary to resolve the waterline and delineate the hydroperiod during half tidal cycles by capturing the waterline hourly from the headwaters to a piezometer transect 260 meters north. The Helikite is an ideal instrument for local investigations of surface hydrology due to its maneuverability, low cost, ability to remain aloft for extended time over a fixed point, and ability to capture high-resolution images. Photographs taken from aircraft do not provide the detail necessary to determine the waterline on the marsh surface. The near-IR images make the waterline more distinct by increasing the difference between wet and dry ground. In the headwaters of Crab Haul Creek, individual crab burrows are detected by automated image classification and the number of crab burrows and their spatial density is tracked from January-August. Crab burrows are associated with the unvegetated region at the creek head, and we relate their change over time to the propagation of the creek farther into the tidal basin. Plant zonation is influenced by the hydroperiod, but also may be affected by salinity, water table depth, and
Digital Repository Service at National Institute of Oceanography (India)
Fernandes, L.; Nayak, G.N.; Ilangovan, D.; Borole, D.V.
Two core sediment samples; one from inner part (ManI) and the other closer to the mouth (ManII; were collected from the intertidal regions of Manori, a tidally influenced creek near Mumbai, India. Both the cores were subjected to various geochemical...
Nelson, N.; Munoz-Carpena, R.; Neale, P.; Tzortziou, M.; Megonigal, P.
2017-12-01
Due to strong abiotic forcing, dissolved oxygen (DO) in shallow tidal creeks often disobeys the conventional explanation of general aquatic DO cycling as biologically-regulated. In the present work, we seek to quantify the relative importance of abiotic (hydrologic and climatic), and biotic (primary productivity as represented by chlorophyll-a) descriptors of tidal creek DO. By fitting multiple linear regression models of DO to hourly chlorophyll-a, water quality, hydrology, and weather data collected in a tidal creek of a Chesapeake Bay marsh (Maryland, USA), temporal shifts (summer - early winter) in the relative importance of tidal creek DO descriptors were uncovered. Moreover, this analysis identified an alternative approach to evaluating tidal stage as a driver of DO by dividing stage into two DO-relevant variables: stage above and below bankfull depth. Within the hydrologic variable class, stage below bankfull depth dominated as an important descriptor, thus highlighting the role of pore water drainage and mixing as influential processes forcing tidal creek DO. Study findings suggest that tidal creek DO dynamics are explained by a balance of hydrologic, climatic, and biotic descriptors during warmer seasons due to many of these variables (i.e., chlorophyll-a, water temperature) acting as tracers of estuarine-marsh water mixing; conversely, in early winter months when estuarine and marsh waters differ less distinctly, hydrologic variables increase in relative importance as descriptors of tidal creek DO. These findings underline important distinctions in the underlying mechanisms dictating DO variability in shallow tidal marsh-creek environments relative to open water estuarine systems.
Elliott, Emily A.; Monbureau, Elaine; Walters, Glenn W.; Elliott, Mark A.; McKee, Brent A.; Rodriguez, Antonio B.
2017-12-01
Identifying the source and abundance of sediment transported within tidal creeks is essential for studying the connectivity between coastal watersheds and estuaries. The fine-grained suspended sediment load (SSL) makes up a substantial portion of the total sediment load carried within an estuarine system and efficient sampling of the SSL is critical to our understanding of nutrient and contaminant transport, anthropogenic influence, and the effects of climate. Unfortunately, traditional methods of sampling the SSL, including instantaneous measurements and automatic samplers, can be labor intensive, expensive and often yield insufficient mass for comprehensive geochemical analysis. In estuaries this issue is even more pronounced due to bi-directional tidal flow. This study tests the efficacy of a time-integrated mass sediment sampler (TIMS) design, originally developed for uni-directional flow within the fluvial environment, modified in this work for implementation the tidal environment under bi-directional flow conditions. Our new TIMS design utilizes an 'L' shaped outflow tube to prevent backflow, and when deployed in mirrored pairs, each sampler collects sediment uniquely in one direction of tidal flow. Laboratory flume experiments using dye and particle image velocimetry (PIV) were used to characterize the flow within the sampler, specifically, to quantify the settling velocities and identify stagnation points. Further laboratory tests of sediment indicate that bidirectional TIMS capture up to 96% of incoming SSL across a range of flow velocities (0.3-0.6 m s-1). The modified TIMS design was tested in the field at two distinct sampling locations within the tidal zone. Single-time point suspended sediment samples were collected at high and low tide and compared to time-integrated suspended sediment samples collected by the bi-directional TIMS over the same four-day period. Particle-size composition from the bi-directional TIMS were representative of the array of
Hickman, R. Edward
1987-01-01
Loads of suspended sediment, phosphorus, nitrogen, biochemical oxygen demand, and dissolved silica discharged to the tidal Potomac River and Estuary during the !979-81 water years from three local nonpoint sources have been calculated. The loads in rain falling directly upon the tidal water surface and from overflows of the combined sewer system of the District of Columbia were determined from available information. Loads of materials in the streamflow from local watersheds draining directly to the tidal Potomac River and Estuary downstream from Chain Bridge in Washington, D.C., were calculated from samples of streamflow leaving five monitored watersheds. Average annual yields of substances leaving three urban watersheds (Rock Creek and the Northwest and Northeast Branches of the Anacostia River) and the rural Saint Clements Creek watershed were calculated either by developing relationships between concentration and streamflow or by using the mean of measured concentrations. Yields calculated for the 1979-81 water years are up to 2.3 times period-of-record yields because of greater than average streamflow and stormflow during this 3-year period. Period-of-record yields of suspended sediment from the three urban watersheds and the Saint Clements Creek watershed do not agree with yields reported by other studies. The yields from the urban watersheds are 17 to 51 percent of yields calculated using sediment-concentration data collected during the 1960-62 water years. Previous studies suggest that this decrease is at least partly due to the imposition of effective sediment controls at construction sites and to the construction of two multipurpose reservoirs. The yield calculated for the rural Saint Clements Creek watershed is at least twice the yields calculated for other rural watersheds, a result that may be due to most of the samples of this stream being taken during the summer of the 1981 water year, a very dry period. Loads discharged from all local tributary
The role of bank collapse on tidal creek ontogeny: A novel process-based model for bank retreat
Gong, Zheng; Zhao, Kun; Zhang, Changkuan; Dai, Weiqi; Coco, Giovanni; Zhou, Zeng
2018-06-01
Bank retreat in coastal tidal flats plays a primary role on the planimetric shape of tidal creeks and is commonly driven by both flow-induced bank erosion and gravity-induced bank collapse. However, existing modelling studies largely focus on bank erosion and overlook bank collapse. We build a bank retreat model coupling hydrodynamics, bank erosion and bank collapse. To simulate the process of bank collapse, a stress-deformation model is utilized to calculate the stress variation of bank soil after bank erosion, and the Mohr-Coulomb failure criterion is then applied to evaluate the stability of the tidal creek bank. Results show that the bank failure process can be categorized into three stages, i.e., shear failure at the bank toe (stage I), tensile failure on the bank top (stage II), and sectional cracking from the bank top to the toe (stage III). With only bank erosion, the planimetric shapes of tidal creeks are funneled due to the gradually seaward increasing discharge. In contrast to bank erosion, bank collapse is discontinuous, and the contribution of bank collapse to bank retreat can reach 85%, highlighting that the expansion of tidal creeks can be dominated by bank collapse process. The planimetric shapes of tidal creeks are funneled with a much faster expansion rate when bank collapse is considered. Overall, this study makes a further step toward more physical and realistic simulation of bank retreat in estuarine and coastal settings and the developed bank collapse module can be readily included in other morphodynamic models.
Tidal and meteorological forcing of sediment transport in tributary mudflat channels.
Ralston, David K; Stacey, Mark T
2007-06-01
Field observations of flow and sediment transport in a tributary channel through intertidal mudflats indicate that suspended sediment was closely linked to advection and dispersion of a tidal salinity front. During calm weather when tidal forcing was dominant, high concentrations of suspended sediment advected up the mudflat channel in the narrow region between salty water from San Francisco Bay and much fresher runoff from the small local watershed. Salinity and suspended sediment dispersed at similar rates through each tidal inundation, such that during receding ebbs the sediment pulse had spread spatially and maximum concentrations had decreased. Net sediment transport was moderately onshore during the calm weather, as asymmetries in stratification due to tidal straining of the salinity front enhanced deposition, particularly during weaker neap tidal forcing. Sediment transport by tidal forcing was periodically altered by winter storms. During storms, strong winds from the south generated wind waves and temporarily increased suspended sediment concentrations. Increased discharge down the tributary channels due to precipitation had more lasting impact on sediment transport, supplying both buoyancy and fine sediment to the system. Net sediment transport depended on the balance between calm weather tidal forcing and perturbations by episodic storms. Net transport in the tributary channel was generally off-shore during storms and during calm weather spring tides, and on-shore during calm weather neap tides.
Shanahan, M.; Wilson, A. M.; Smith, E. M.
2017-12-01
Coastal upland development has been shown to negatively impact surface water quality in tidal creeks in the southeastern US, but less is known about its impact on groundwater. We sampled groundwater in the upland and along the marsh perimeter of tidal creeks located within developed and undeveloped watersheds. Samples were analyzed for salinity, dissolved organic carbon, nitrogen and phosphorus concentrations. Groundwater samples collected from the upland in developed and undeveloped watersheds were compared to study the impact of development on groundwater entering the marsh. Groundwater samples collected along the marsh perimeter were analyzed to study the impact of marsh width variability on groundwater quality within each creek. Preliminary results suggest a positive correlation between salinity and marsh width in undeveloped watersheds, and a higher concentration of nutrients in developed versus undeveloped watersheds.
Stream sediment detailed geochemical survey for Date Creek Basin, Arizona
International Nuclear Information System (INIS)
Butz, T.R.; Tieman, D.J.; Grimes, J.G.; Bard, C.S.; Helgerson, R.N.; Pritz, P.M.; Wolf, D.A.
1981-01-01
The purpose of the Date Creek Supplement is to characterize the chemistry of sediment samples representing stream basins in which the Anderson Mine (and related prospects) occur. Once characterized, the chemistry is then used to delineate other areas within the Date Creek Basin where stream sediment chemistry resembles that of the Anderson Mine area. This supplementary report examines more closely the data from sediment samples taken in 239 stream basins collected over a total area of approximately 900 km 2 (350 mi 2 ). Cluster and discriminant analyses are used to characterize the geochemistry of the stream sediment samples collected in the Date Creek Basin. Cluster and discriminant analysis plots are used to delineate areas having a potential for uranium mineralization similar to that of the Anderson Mine
Baruch Institute for Marine and Coastal Sciences, Univ of South Carolina — A group of eight tidal creeks dominated by oysters, Crassostrea virginica, in North Inlet, South Carolina, USA were studied using a replicated BACI (Before - After...
Water and suspended sediment division at a stratified tidal junction
Buschman, F.A.; Vegt, M. van der; Hoitink, A.J.F.; Hoekstra, P.
2013-01-01
Tidal junctions play a crucial role in the transport of water, salt, and sediment through a delta distributary network. Water, salt and sediment are exchanged at tidal junctions, thereby influencing the transports in the connecting branches and the overall dynamics of the system. This paper
Water and suspended sediment division at a stratified tidal junction
Buschman, F.A.; Vegt, van der M.; Hoitink, A.J.F.; Hoekstra, P.
2013-01-01
[1] Tidal junctions play a crucial role in the transport of water, salt, and sediment through a delta distributary network. Water, salt and sediment are exchanged at tidal junctions, thereby influencing the transports in the connecting branches and the overall dynamics of the system. This paper
A Tidally Averaged Sediment-Transport Model for San Francisco Bay, California
Lionberger, Megan A.; Schoellhamer, David H.
2009-01-01
A tidally averaged sediment-transport model of San Francisco Bay was incorporated into a tidally averaged salinity box model previously developed and calibrated using salinity, a conservative tracer (Uncles and Peterson, 1995; Knowles, 1996). The Bay is represented in the model by 50 segments composed of two layers: one representing the channel (>5-meter depth) and the other the shallows (0- to 5-meter depth). Calculations are made using a daily time step and simulations can be made on the decadal time scale. The sediment-transport model includes an erosion-deposition algorithm, a bed-sediment algorithm, and sediment boundary conditions. Erosion and deposition of bed sediments are calculated explicitly, and suspended sediment is transported by implicitly solving the advection-dispersion equation. The bed-sediment model simulates the increase in bed strength with depth, owing to consolidation of fine sediments that make up San Francisco Bay mud. The model is calibrated to either net sedimentation calculated from bathymetric-change data or measured suspended-sediment concentration. Specified boundary conditions are the tributary fluxes of suspended sediment and suspended-sediment concentration in the Pacific Ocean. Results of model calibration and validation show that the model simulates the trends in suspended-sediment concentration associated with tidal fluctuations, residual velocity, and wind stress well, although the spring neap tidal suspended-sediment concentration variability was consistently underestimated. Model validation also showed poor simulation of seasonal sediment pulses from the Sacramento-San Joaquin River Delta at Point San Pablo because the pulses enter the Bay over only a few days and the fate of the pulses is determined by intra-tidal deposition and resuspension that are not included in this tidally averaged model. The model was calibrated to net-basin sedimentation to calculate budgets of sediment and sediment-associated contaminants. While
Siemion, Jason; McHale, Michael R.; Davis, Wae Danyelle
2016-12-05
Suspended-sediment concentrations (SSCs) and turbidity were monitored within the Beaver Kill, Stony Clove Creek, and Warner Creek tributaries to the upper Esopus Creek in New York, the main source of water to the Ashokan Reservoir, from October 1, 2010, through September 30, 2014. The purpose of the monitoring was to determine the effects of suspended-sediment and turbidity reduction projects (STRPs) on SSC and turbidity in two of the three streams; no STRPs were constructed in the Beaver Kill watershed. During the study period, four STRPs were completed in the Stony Clove Creek and Warner Creek watersheds. Daily mean SSCs decreased significantly for a given streamflow after the STRPs were completed. The most substantial decreases in daily mean SSCs were measured at the highest streamflows. Background SSCs, as measured in water samples collected in upstream reference stream reaches, in all three streams in this study were less than 5 milligrams per liter during low and high streamflows. Longitudinal stream sampling identified stream reaches with failing hillslopes in contact with the stream channel as the primary sediment sources in the Beaver Kill and Stony Clove Creek watersheds.
Suspended sediment transport trough a large fluvial-tidal channel network
Wright, Scott A.; Morgan-King, Tara L.
2015-01-01
The confluence of the Sacramento and San Joaquin Rivers, CA, forms a large network of interconnected channels, referred to as the Sacramento-San Joaquin Delta (the Delta). The Delta comprises the transition zone from the fluvial influences of the upstream rivers and tidal influences of San Francisco Bay downstream. Formerly an extensive tidal marsh, the hydrodynamics and geomorphology of Delta have been substantially modified by humans to support agriculture, navigation, and water supply. These modifications, including construction of new channels, diking and draining of tidal wetlands, dredging of navigation channels, and the operation of large pumping facilities for distribution of freshwater from the Delta to other parts of the state, have had a dramatic impact on the physical and ecological processes within the Delta. To better understand the current physical processes, and their linkages to ecological processes, the USGS maintains an extensive network of flow, sediment, and water quality gages in the Delta. Flow gaging is accomplished through use of the index-velocity method, and sediment monitoring uses turbidity as a surrogate for suspended-sediment concentration. Herein, we present analyses of the transport and dispersal of suspended sediment through the complex network of channels in the Delta. The primary source of sediment to the Delta is the Sacramento River, which delivers pulses of sediment primarily during winter and spring runoff events. Upon reaching the Delta, the sediment pulses move through the fluvial-tidal transition while also encountering numerous channel junctions as the Sacramento River branches into several distributary channels. The monitoring network allows us to track these pulses through the network and document the dominant transport pathways for suspended sediment. Further, the flow gaging allows for an assessment of the relative effects of advection (the fluvial signal) and dispersion (from the tides) on the sediment pulses as they
Guimond, J. A.; Seyfferth, A.; Michael, H. A.
2017-12-01
Salt marshes are biogeochemical hotspots where large quantities of carbon are processed and stored. High primary productivity and deposition of carbon-laden sediment enable salt marsh soils to accumulate and store organic carbon. Conversely, salt marshes can laterally export carbon from the marsh platform to the tidal channel and eventually the ocean via tidal pumping. However, carbon export studies largely focus on tidal channels, missing key physical and biogeochemical mechanisms driving the mobilization of dissolved organic carbon (DOC) within the marsh platform and limiting our understanding of and ability to predict coastal carbon dynamics. We hypothesize that iron redox dynamics mediate the mobilization/immobilization of DOC in the top 30 cm of salt marsh sediment near tidal channels. The mobilized DOC can then diffuse into the flooded surface water or be advected to tidal channels. To elucidate DOC dynamics driven by iron redox cycles, we measured porewater DOC, Fe(II), total iron, total sulfate, pH, redox potential, and electrical conductivity (EC) beside the creek, at the marsh levee, and in the marsh interior in a mid-latitude tidal salt marsh in Dover, Delaware. Samples were collected at multiple tide stages during a spring and neap tide at depths of 5-75cm. Samples were also collected from the tidal channel. Continuous Eh measurements were made using in-situ electrodes. A prior study shows that DOC and Fe(II) concentrations vary spatially across the marsh. Redox conditions near the creek are affected by tidal oscillations. High tides saturate the soil and decrease redox potential, whereas at low tide, oxygen enters the sediment and increases the Eh. This pattern is always seen in the top 7-10cm of sediment, with more constant low Eh at depth. However, during neap tides, this signal penetrates deeper. Thus, between the creek and marsh levee, hydrology mediates redox conditions. Based on porewater chemistry, if DOC mobilization can be linked to redox
David, Frank; Marchand, Cyril; Taillardat, Pierre; Thành-Nho, Nguyễn; Meziane, Tarik
2018-01-01
Mangrove forests are highly productive ecosystems and mangrove-derived organic matter has generally been assumed to play a basal role in sustaining coastal food webs. However, the mechanisms of mangrove-derived organic matter utilisation by consumers are not fully understood. In this study, we were interested in hourly changes in the nutritional quality of suspended particulate matter (SPM) entering and departing a mangrove creek during a tidal cycle. We determined the fatty acid composition and δ13C stable isotope signature of SPM during a 26 h tidal cycle in a creek of the Can Gio Mangrove Biosphere Reserve (Southern Vietnam). Regarding fatty acids, the nutritional quality of SPM was low during most of the tidal cycle. However, it greatly increased during the first part of the strongest flood tide, occurring during daytime. The pulse of highly nutritive organic matter brought to the ecosystem was mostly composed of algal cells growing in specific shallow zones of the mangrove, that use nutrients and CO2 exported during the preceding ebb tide and originating from the mineralisation of mangrove-derived organic matter, as evidenced by their δ13C signatures. This study confirms that mangrove-derived carbon plays a basal role in sustaining trophic webs of mangrove tidal creeks, but that its nutritive value is greatly enhanced when a first step of mineralisation is achieved and CO2 is photosynthesised by algal cells.
Directory of Open Access Journals (Sweden)
Daniel A. Marchio
2016-05-01
Full Text Available This study compares carbon sequestration rates along two independent tidal mangrove creeks near Naples Bay in Southwest Florida, USA. One tidal creek is hydrologically disturbed due to upstream land use changes; the other is an undisturbed reference creek. Soil cores were collected in basin, fringe, and riverine hydrogeomorphic settings along each of the two tidal creeks and analyzed for bulk density, total organic carbon profiles, and sediment accretion. Radionuclides 137Cs and 210Pb were used to estimate recent sediment accretion and carbon sequestration rates. Carbon sequestration rates (mean ± standard error for seven sites in the two tidal creeks on the Naples Bay (98 ± 12 g-C m−2·year−1 (n = 18 are lower than published global means for mangrove wetlands, but consistent with other estimates from the same region. Mean carbon sequestration rates in the reference riverine setting were highest (162 ± 5 g-C m−2·year−1, followed by rates in the reference fringe and disturbed riverine settings (127 ± 6 and 125 ± 5 g-C m−2·year−1, respectively. The disturbed fringe sequestered 73 ± 10 g-C m−2·year−1, while rates within the basin settings were 50 ± 4 g-C m−2·year−1 and 47 ± 4 g-C m−2·year−1 for the reference and disturbed creeks, respectively. These data support our hypothesis that mangroves along a hydrologically disturbed tidal creek sequestered less carbon than did mangroves along an adjacent undisturbed reference creek.
Sediment sources and storages in the urbanizing South Creek catchment, Lake Macquarie, NSW
International Nuclear Information System (INIS)
Curtis, S.J.
1988-10-01
An investigation of the sediment source areas and sediment storages has been undertaken in the South Creek catchment, Lake Macquarie, NSW. Source areas have been examined by analyzing suspended sediment concentrations, field measurements and observations, and caesium-137 values. The caesium-137 technique and field measurements were used to study the sediment storages on the South Creek flood plain. Particle size analysis of sediments on the slopes and flood plain were undertaken to provide information on the efficiency of the sediment transport system. The results of these investigations indicate that the developing urban areas are the main sources of poorest water quality (in terms of suspended sediment) in the South Creek catchment. The open woodland, rural and established urban areas were minor sediment source areas, although the open woodland had the potential to become a major sediment source if disturbed by human activities. The developing urban areas had efficient sediment transport systems, while the open woodland and rural areas tended to deposit sediment locally. The upstream section of the flood plain was found to be storing more sediment than the downstream section. The study revealed that when urban development occurs on the steeper gradients of the South Creek catchment erosion processes are greatly accelerated and thus the developing urban area becomes the major source of poorest water quality in the catchment. The importance of the developing urban area as a sediment source needs to be considered in any future land developments in urbanizing drainage basins
Optical dating of young tidal sediments in the Danish Wadden Sea
DEFF Research Database (Denmark)
Madsen, Anni Tindahl; Murray, A. S.; Andersen, Thorbjørn Joest
2007-01-01
reliable and reproducible results in cores from sub-, inter- and supra-tidal sediments, ranging from only a few years up to ~1000 years old, confirming its value in the estimation of estuarine accretion rates. With OSL it is, for the first time, possible to date sediment cores from silty and sandy tidal...... flats, providing a new approach to the problem of evaluation of stability and calculation of sediment budgets for estuaries and coastal lagoons....
Environmental impact assessment of Kachchh tidal power project
International Nuclear Information System (INIS)
Yadav, Ramanand; Lal, B.B.
1995-01-01
The Kachchh tidal power development project is a single-basin, single -effect and ebb generation development by construction of a tidal power barrage of about 3.25 km length across Hansthal creek. The project may disturb the ecosystem of the region. The paper deals in detail the environmental impacts of the project on climate, water velocity, flow and sedimentation pattern, water quality, flora and fauna, fishery, tourism and recreation, wild life, public health and socio-economic conditions. (author). 4 refs., 1 fig., 2 tabs
Lee, Guan-hong; Kang, KiRyong
2018-05-01
A field campaign was conducted to better understand the influence of wave action, in terms of turbulence and bed shear stress, on sediment resuspension and transport processes on a protected tidal flat. An H-frame was deployed in a tidal channel south of Gangwha Island for 6 tidal cycles during November 2006 with instrumentation including an Acoustic Doppler Velocimeter, an Acoustic Backscatter System, and an Optical Backscatter Sensor. During calm conditions, the current-induced shear was dominant and responsible for suspending sediments during the accelerating phases of flood and ebb. During the high-tide slack, both bed shear stress and suspended sediment concentration were reduced. The sediment flux was directed landward due to the scour-lag effect over a tidal cycle. On the other hand, when waves were stronger, the wave-induced turbulence appeared to keep sediments in suspension even during the high-tide slack, while the current-induced shear remained dominant during the accelerating phases of flood and ebb. The sediment flux under strong waves was directed offshore due to the sustained high suspended sediment concentration during the high-tide slack. Although strong waves can induce offshore sediment flux, infrequent events with strong waves are unlikely to alter the long-term accretion of the protected southern Gangwha tidal flats.
Discharge, sediment, and water chemistry in Clear Creek, western Nevada, water years 2013–16
Huntington, Jena M.; Riddle, Daniel J.; Paul, Angela P.
2018-05-01
Clear Creek is a small stream that drains the eastern Carson Range near Lake Tahoe, flows roughly parallel to the Highway 50 corridor, and discharges to the Carson River near Carson City, Nevada. Historical and ongoing development in the drainage basin is thought to be affecting Clear Creek and its sediment-transport characteristics. Previous studies from water years (WYs) 2004 to 2007 and from 2010 to 2012 evaluated discharge, selected water-quality parameters, and suspended-sediment concentrations, loads, and yields at three Clear Creek sampling sites. This report serves as a continuation of the data collection and analyses of the Clear Creek discharge regime and associated water-chemistry and sediment concentrations and loads during WYs 2013–16.Total annual sediment loads ranged from 870 to 5,300 tons during WYs 2004–07, from 320 to 1,770 tons during WYs 2010–12, and from 50 to 200 tons during WYs 2013–16. Ranges in annual loads during the three study periods were not significantly different; however, total loads were greater during 2004–07 than they were during 2013–16. Annual suspended-sediment loads in WYs 2013–16 showed no significant change since WYs 2010–12 at sites 1 (U.S. Geological Survey reference site 10310485; Clear Creek above Highway 50, near Spooner Summit, Nevada) or 2 (U.S. Geological Survey streamgage 10310500; Clear Creek above Highway 50, near Spooner Summit, Nevada), but significantly lower loads at site 3 (U.S. Geological Survey site 10310518; Clear Creek at Fuji Park, at Carson City, Nevada), supporting the theory of sediment deposition between sites 2 and 3 where the stream gradient becomes more gradual. Currently, a threshold discharge of about 3.3 cubic feet per second is required to mobilize streambed sediment (bedload) from site 2 in Clear Creek. Mean daily discharge was significantly lower in 2010–12 than in 2004–07 and also significantly lower in 2013–16 than in 2010–12. During this study, lower bedload, and
Baruch Institute for Marine and Coastal Sciences, Univ of South Carolina — Ground water level elevations were collected every 10 to 15 days from piezometers stationed along three forest-marsh-tidal creek transects (B, C, and D) across the...
Hourly and daily variation of sediment redox potential in tidal wetland sediments
Catallo, W. James
1999-01-01
Variation of electrochemical oxidation-reduction (redox) potential was examined in surface salt march sediments under conditions of flooding and tidal simulation in mesocosms and field sites. Time series were generated of redox potential measured in sediment profiles at 2-10 cm depth using combination Pt-Ag/AgCl (ORP) electrodes. Redox potential data were acquired at rapid rates (1-55 samples/h) over extended periods (3-104 days) along with similar times series of temperature (water, air, soil) and pH. It was found that redox potential vaired as a result of water level changes and was unrelated to diurnal changes in temperature or pH, the latter of which changed by 370 mV redox potential decrease in under 48 hours). Attenuatoin of microbial activity by [gamma] y-radiation and toxic chemicals elimintated this response. In tidal salt marsh mesocosms where the sediment-plant assemblages were exposed to a simulated diurnal tide, redox potenial oscillations of 40-300 mV amplitude were recoded that has the same periodicity as the flood-drain cycle. Periodic redoc potential time series were observed repeatedly in sediments receiving tidal pulsing but not in those sediments exposed to static hydrological conditions. Data collected over 12 days from a coastal marsh site experiencing diurnal tides showed similar fluctuations in redox potential. Data from the experimentents indicated that (a) redox potential can be a dynamic, nonlinear variable in coastal and estuarine wetland sediments over hourly and daily scales, and the designs of biogeochemical experiments should reflect this, (b) redox potential can change rapidly and signigicantly in coastal wetland sediments in response of flooding and draining, (c) microbial community processes are primarily determinants of the time course of redox potential in wetland sediments, and elimination of inhibition of microbial activity (e.g. by pollutants) can significantly alter that behavior, and (d) fast redox potential dynamics appear
Inferring tidal wetland stability from channel sediment fluxes: Observations and a conceptual model
Ganju, Neil K.; Nidzieko, Nicholas J.; Kirwan, Matthew L.
2013-12-01
and climatic forces have modified the geomorphology of tidal wetlands over a range of timescales. Changes in land use, sediment supply, river flow, storminess, and sea level alter the layout of tidal channels, intertidal flats, and marsh plains; these elements define wetland complexes. Diagnostically, measurements of net sediment fluxes through tidal channels are high-temporal resolution, spatially integrated quantities that indicate (1) whether a complex is stable over seasonal timescales and (2) what mechanisms are leading to that state. We estimated sediment fluxes through tidal channels draining wetland complexes on the Blackwater and Transquaking Rivers, Maryland, USA. While the Blackwater complex has experienced decades of degradation and been largely converted to open water, the Transquaking complex has persisted as an expansive, vegetated marsh. The measured net export at the Blackwater complex (1.0 kg/s or 0.56 kg/m2/yr over the landward marsh area) was caused by northwesterly winds, which exported water and sediment on the subtidal timescale; tidally forced net fluxes were weak and precluded landward transport of suspended sediment from potential seaward sources. Though wind forcing also exported sediment at the Transquaking complex, strong tidal forcing and proximity to a turbidity maximum led to an import of sediment (0.031 kg/s or 0.70 kg/m2/yr). This resulted in a spatially averaged accretion of 3.9 mm/yr, equaling the regional relative sea level rise. Our results suggest that in areas where seaward sediment supply is dominant, seaward wetlands may be more capable of withstanding sea level rise over the short term than landward wetlands. We propose a conceptual model to determine a complex's tendency toward stability or instability based on sediment source, wetland channel location, and transport mechanisms. Wetlands with a reliable portfolio of sources and transport mechanisms appear better suited to offset natural and anthropogenic loss.
White Oak Creek embayment sediment retention structure design and construction
International Nuclear Information System (INIS)
Van Hoesen, S.D.; Kimmell, B.L.; Page, D.G.; Wilkerson, R.B.; Hudson, G.R.; Kauschinger, J.L.; Zocolla, M.
1994-01-01
White Oak Creek is the major surface water drainage throughout the Department of Energy (DOE) Oak Ridge National Laboratory (ORNL). Samples taken from the lower portion of the creek revealed high levels of Cesium 137 and lower level of Cobalt 60 in near surface sediment. Other contaminants present in the sediment included: lead, mercury, chromium, and PCBs. In October 1990, DOE, US Environmental Protection Agency (EPA), and Tennessee Department of Environment and Conservation (TDEC) agreed to initiate a time critical removal action in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) to prevent the transport of the contaminated sediments into the Clinch River system. This paper discusses the environmental, regulatory, design, and construction issues that were encountered in conducting the remediation work
Geometry of tidal inlet systems : A key factor for the net sediment transport in tidal inlets
Ridderinkhof, W.; de Swart, H. E.; van der Vegt, M.; Alebregtse, N. C.; Hoekstra, P.
2014-01-01
The net transport of sediment between the back-barrier basin and the sea is an important process for determining the stability of tidal inlet systems. Earlier studies showed that in a short basin, tidal flats favor peak ebb-currents stronger than peak flood currents, implying export of coarse
Association of radionuclides with streambed sediments in White Oak Creek watershed
International Nuclear Information System (INIS)
Spalding, B.P.; Cerling, T.E.
1979-09-01
Radionuclides are found in much higher concentrations on streambed sediment than in the water of White Oak Creek. Selective extraction of sediments demonstrates that 60 Co is immobilized in a nonexchangeable form in the ferromanganese hydrous oxide coatings on the sediments; 90 Sr occurs predominantly in an exchangeable form on clay, iron oxides, and ferromanganese hydrous oxides; 137 Cs occurs in a nonexchangeable and strongly bound form on clays which compose the dominant rock (Conasauga shale) in the watershed. The fine-gravel to coarse-sand size fraction of streambed sediments is the most suitable fraction for radionuclide analysis because of its abundance in the sediment and its high concentration of radionuclides compared to larger and smaller size fractions. A preliminary survey of all major tributes in White Oak Creek shows that radionuclide analysis of streambed sediments is a very useful technique to locate sources of radioactive contamination
Beaver dams and channel sediment dynamics on Odell Creek, Centennial Valley, Montana, USA
Levine, Rebekah; Meyer, Grant A.
2014-01-01
Beaver dams in streams are generally considered to increase bed elevation through in-channel sediment storage, thus, reintroductions of beaver are increasingly employed as a restoration tool to repair incised stream channels. Here we consider hydrologic and geomorphic characteristics of the study stream in relation to in-channel sediment storage promoted by beaver dams. We also document the persistence of sediment in the channel following breaching of dams. Nine reaches, containing 46 cross-sections, were investigated on Odell Creek at Red Rock Lakes National Wildlife Refuge, Centennial Valley, Montana. Odell Creek has a snowmelt-dominated hydrograph and peak flows between 2 and 10 m3 s- 1. Odell Creek flows down a fluvial fan with a decreasing gradient (0.018-0.004), but is confined between terraces along most of its length, and displays a mostly single-thread, variably sinuous channel. The study reaches represent the overall downstream decrease in gradient and sediment size, and include three stages of beaver damming: (1) active; (2) built and breached in the last decade; and (3) undammed. In-channel sediment characteristics and storage were investigated using pebble counts, fine-sediment depth measurements, sediment mapping and surveys of dam breaches. Upstream of dams, deposition of fine (≤ 2 mm) sediment is promoted by reduced water surface slope, shear stress and velocity, with volumes ranging from 48 to 182 m3. High flows, however, can readily transport suspended sediment over active dams. Variations in bed-sediment texture and channel morphology associated with active dams create substantial discontinuities in downstream trends and add to overall channel heterogeneity. Observations of abandoned dam sites and dam breaches revealed that most sediment stored above beaver dams is quickly evacuated following a breach. Nonetheless, dam remnants trap some sediment, promote meandering and facilitate floodplain development. Persistence of beaver dam sediment
Extractable organics in surface sediments from Thana creek and Bombay harbour
Digital Repository Service at National Institute of Oceanography (India)
Rokade, M.A.; Bhosle, N.B.; Kadam, A.N.
Considerable variations in hydrocarbon and fatty acid levels in surface sediments from Thana creek and Bombay harbour were observed Sediments from the westernside nearshore locations yielded higher values The residues were characterised by infrared...
Inferring tidal wetland stability from channel sediment fluxes: observations and a conceptual model
Ganju, Neil K.; Nidzieko, Nicholas J.; Kirwan, Matthew L.
2013-01-01
Anthropogenic and climatic forces have modified the geomorphology of tidal wetlands over a range of timescales. Changes in land use, sediment supply, river flow, storminess, and sea level alter the layout of tidal channels, intertidal flats, and marsh plains; these elements define wetland complexes. Diagnostically, measurements of net sediment fluxes through tidal channels are high-temporal resolution, spatially integrated quantities that indicate (1) whether a complex is stable over seasonal timescales and (2) what mechanisms are leading to that state. We estimated sediment fluxes through tidal channels draining wetland complexes on the Blackwater and Transquaking Rivers, Maryland, USA. While the Blackwater complex has experienced decades of degradation and been largely converted to open water, the Transquaking complex has persisted as an expansive, vegetated marsh. The measured net export at the Blackwater complex (1.0 kg/s or 0.56 kg/m2/yr over the landward marsh area) was caused by northwesterly winds, which exported water and sediment on the subtidal timescale; tidally forced net fluxes were weak and precluded landward transport of suspended sediment from potential seaward sources. Though wind forcing also exported sediment at the Transquaking complex, strong tidal forcing and proximity to a turbidity maximum led to an import of sediment (0.031 kg/s or 0.70 kg/m2/yr). This resulted in a spatially averaged accretion of 3.9 mm/yr, equaling the regional relative sea level rise. Our results suggest that in areas where seaward sediment supply is dominant, seaward wetlands may be more capable of withstanding sea level rise over the short term than landward wetlands. We propose a conceptual model to determine a complex's tendency toward stability or instability based on sediment source, wetland channel location, and transport mechanisms. Wetlands with a reliable portfolio of sources and transport mechanisms appear better suited to offset natural and
Directory of Open Access Journals (Sweden)
O. A. Davies
2013-01-01
Full Text Available Okpoka Creek of the Upper Bonny Estuary in the Niger Delta is a tidal creek receiving organic anthropogenic effluents from its environs. The study investigated the influence of tides (low and high on the species composition, diversity, abundance, and distribution of phytoplankton. The surface water and phytoplankton samples were collected monthly from May 2004 to April 2006 at both tides from ten stations according to standard methods. Phytoplankton was identified microscopically. Species diversity was calculated using standard indices. Data analyses were done using analysis of variance, Duncan multiple range, and descriptive statistics. Phosphate and ammonia exceeded international acceptable levels of 0.10 mg/L for natural water bodies indicating high nutrient status, organic matter, and potential pollutants. A total of 158 species of phytoplankton were identified. Diatoms dominated the phytoplankton (62.9%. Diversity indices of diatoms were 1.5±0.03 (Margalef and 0.8±0.01 (Shannon. Pollution-indicator species such as Navicula microcephala, Nitzschia sigma, Synedra ulna (diatoms, Cladophora glomerata (green alga, Euglena acus (euglenoid, Anabeana spiroides (blue-green alga, and Ceratium furca (dinoflagellate were recorded at either only low, high or both tides. Concerted environmental surveillance on Upper Bonny Estuary is advocated to reduce the inflow of pollutants from the Bonny Estuary into this Creek caused by tidal influence.
McLachlan, R. L.; Ogston, A. S.; Allison, M. A.
2017-09-01
River gauging stations are often located upriver of tidal propagation where sediment transport processes and storage are impacted by widely varying ratios of marine to freshwater influence. These impacts are not yet thoroughly understood. Therefore, sediment fluxes measured at these stations may not be suitable for predicting changes to coastal morphology. To characterize sediment transport dynamics in this understudied zone, flow velocity, salinity, and suspended-sediment properties (concentration, size, and settling velocity) were measured within the tidal Sông Hậu distributary of the lower Mekong River, Vietnam. Fine-sediment aggregation, settling, and trapping rates were promoted by seasonal and tidal fluctuations in near-bed shear stress as well as the intermittent presence of a salt wedge and estuary turbidity maximum. Beginning in the tidal river, fine-grained particles were aggregated in freshwater. Then, in the interface zone between the tidal river and estuary, impeded near-bed shear stress and particle flux convergence promoted settling and trapping. Finally, in the estuary, sediment retention was further encouraged by stratification and estuarine circulation which protected the bed against particle resuspension and enhanced particle aggregation. These patterns promote mud export ( 1.7 t s-1) from the entire study area in the high-discharge season when fluvial processes dominate and mud import ( 0.25 t s-1) into the estuary and interface zone in the low-discharge season when estuarine processes dominate. Within the lower region of the distributaries, morphological change in the form of channel abandonment was found to be promoted within minor distributaries by feedbacks between channel depth, vertical mixing, and aggregate trapping. In effect, this field study sheds light on the sediment trapping capabilities of the tidal river - estuary interface zone, a relatively understudied region upstream of where traditional concepts place sites of deposition
Geochemical survey of stream sediments of the Piceance Creek Basin, Colorado
Energy Technology Data Exchange (ETDEWEB)
Ringrose, C.D.
1977-01-01
A stream sediment survey was conducted in the Piceance Creek Basin to study the spatial distribution of Zn, Mo, Hg, Cd and As for future baseline considerations. The pH and organic matter were also measured. From samples taken at the mouths (junctions) of most of the named creeks in the basin, it is concluded that none of the streams contained sediments with anomalous trace element concentrations with respect to the basin. But it is thought that Mo and possibly As could be potentially toxic because of their abundance and their mobility under the stream sediments' alkaline condition. From a different sampling plan, designed to describe the background variance of five streams (Roan, Black Sulfur, Parachute, Yellow and Piceance Creeks), it was found that most of the variance occurred at distances from 0-10 m within 2 km stream segments 10 km apart for Mo, Hg, Az, and organic matter. When the variance between the five streams was considered, it was found to dominate the variances of the other factors for Mo, Hg, and Zn. This variance between streams is actually thought to represent the variance between the major drainage system in the basin. When comparison is made between the two sampling design results, it is thought that the trace element concentrations of stream junction samples represented the best range of expected values for the entire basin. The expected ranges of the trace elements from the nested design are thought to be reasonable estimates of preliminary baselines for Parachute Creek, Roan Creek and Black Sulfur Creek within the restricted limits of the streams defined in the text. From the experience gained in pursuing this study, it is thought that composite sampling should be considered, where feasible, to reduce the analytical load and to reduce the small scale variance.
Schwarz, C.; Cox, T.; van Engeland, T.; van Oevelen, D.; van Belzen, J.; van de Koppel, J.; Soetaert, K.; Bouma, T. J.; Meire, P.; Temmerman, S.
2017-10-01
A short-term intensive measurement campaign focused on flow, turbulence, suspended particle concentration, floc dynamics and settling velocities were carried out in a brackish intertidal creek draining into the main channel of the Scheldt estuary. We compare in situ estimates of settling velocities between a laser diffraction (LISST) and an acoustic Doppler technique (ADV) at 20 and 40 cm above bottom (cmab). The temporal variation in settling velocity estimated were compared over one tidal cycle, with a maximum flood velocity of 0.46 m s-1, a maximum horizontal ebb velocity of 0.35 m s-1 and a maximum water depth at high water slack of 2.41 m. Results suggest that flocculation processes play an important role in controlling sediment transport processes in the measured intertidal creek. During high-water slack, particles flocculated to sizes up to 190 μm, whereas at maximum flood and maximum ebb tidal stage floc sizes only reached up to 55 μm and 71 μm respectively. These large differences indicate that flocculation processes are mainly governed by turbulence-induced shear rate. In this study, we specifically recognize the importance of along-channel gradients that places constraints on the application of the acoustic Doppler technique due to conflicts with the underlying assumptions. Along-channel gradients were assessed by additional measurements at a second location and scaling arguments which could be used as an indication whether the Reynolds-flux method is applicable. We further show the potential impact of along-channel advection of flocs out of equilibrium with local hydrodynamics influencing overall floc sizes.
Carbohydrate secretion by phototrophic communities in tidal sediments
de Winder, B.; Staats, N.; Stal, L.J.; Paterson, D.M.
1999-01-01
Two different benthic phototrophic communities on tidal flats were investigated for their carbohydrate content and distribution. Carbohydrates were analysed as two operationally defined fractions, related to the difficulty of extraction from the sediment matrix. Water-soluble (colloidal) and EDTA-
Otero, X. L.; Lucheta, A. R.; Ferreira, T. O.; Huerta-Díaz, M. A.; Lambais, M. R.
2014-06-01
Even though several studies on the geochemical processes occurring in mangrove soils and sediments have been performed, information on the diversity of Archaea and their functional roles in these ecosystems, especially in subsurface environments, is scarce. In this study, we have analyzed the depth distribution of Archaea and their possible relationships with the geochemical transformations of Fe and Mn in a sediment core from a tropical mangrove creek, using 16S rRNA gene profiling and sequential extraction of different forms of Fe and Mn. A significant shift in the archaeal community structure was observed in the lower layers (90-100 cm), coinciding with a clear decrease in total organic carbon (TOC) content and an increase in the percentage of sand. The comparison of the archaeal communities showed a dominance of methanogenic Euryarchaeota in the upper layers (0-20 cm), whereas Crenarchaeota was the most abundant taxon in the lower layers. The dominance of methanogenic Euryarchaeota in the upper layer of the sediment suggests the occurrence of methanogenesis in anoxic microenvironments. The concentrations of Fe-oxyhydroxides in the profile were very low, and showed positive correlation with the concentrations of pyrite and degrees of Fe and Mn pyritization. Additionally, a partial decoupling of pyrite formation from organic matter concentration was observed, suggesting excessive Fe pyritization. This overpyritization of Fe can be explained either by the anoxic oxidation of methane by sulfate and/or by detrital pyrite tidal transportation from the surrounding mangrove soils. The higher pyritization levels observed in deeper layers of the creek sediment were also in agreement with its Pleistocenic origin.
Church, Stan E.; Kirschner, Frederick E.; Choate, LaDonna M.; Lamothe, Paul J.; Budahn, James R.; Brown, Zoe Ann
2008-01-01
Geochemical and radionuclide studies of sediment recovered from eight core sites in the Blue Creek flood plain and Blue Creek delta downstream in Lake Roosevelt provided a stratigraphic geochemical record of the contamination from uranium mining at the Midnite Mine. Sediment recovered from cores in a wetland immediately downstream from the mine site as well as from sediment catchments in Blue Creek and from cores in the delta in Blue Creek cove provided sufficient data to determine the premining geochemical background for the Midnite Mine tributary drainage. These data provide a geochemical background that includes material eroded from the Midnite Mine site prior to mine development. Premining geochemical background for the Blue Creek basin has also been determined using stream-sediment samples from parts of the Blue Creek, Oyachen Creek, and Sand Creek drainage basins not immediately impacted by mining. Sediment geochemistry showed that premining uranium concentrations in the Midnite Mine tributary immediately downstream of the mine site were strongly elevated relative to the crustal abundance of uranium (2.3 ppm). Cesium-137 (137Cs) data and public records of production at the Midnite Mine site provided age control to document timelines in the sediment from the core immediately downstream from the mine site. Mining at the Midnite Mine site on the Spokane Indian Reservation between 1956 and 1981 resulted in production of more than 10 million pounds of U3O8. Contamination of the sediment by uranium during the mining period is documented from the Midnite Mine along a small tributary to the confluence of Blue Creek, in Blue Creek, and into the Blue Creek delta. During the period of active mining (1956?1981), enrichment of base metals in the sediment of Blue Creek delta was elevated by as much as 4 times the concentration of those same metals prior to mining. Cadmium concentrations were elevated by a factor of 10 and uranium by factors of 16 to 55 times premining
1976-03-01
Cattaraugus Creek. Records of wells drilled through the glacial deposits indicate that the elevation of bedrock is between 200 and 300 feet below sea...noticeable, are sketched. An oblique, low-altitude aerial photo of the fall spit complex is shown in Plate 11. The water level at the Keene Marina staff gauge ...Hayes, M.O., and Boothroyd, J. C., 1972, Comparison of ridge and runnel systems in tidal and non-tidal environ- ments: Jour. Sedimentary Petrology , v
Azhikodan, Gubash; Yokoyama, Katsuhide
2018-03-01
The erosion and deposition dynamics of fine sediment in a highly turbid estuarine channel were successfully surveyed during the period from August 29 to September 12, 2009 using an echo sounder in combination with a high-resolution acoustic Doppler current profiler. Field measurements were conducted focusing on the tide driven dynamics of suspended sediment concentration (SSC), and fluid mud at the upstream of the macrotidal Chikugo river estuary during semidiurnal and fortnightly tidal cycles. Morphological evolution was observed especially during the spring tide over a period of two weeks. The elevation of the channel bed was stable during neap tide, but it underwent fluctuations when the spring tide occurred owing to the increase in the velocity and shear stress. Two days of time lag were observed between the maximum SSC and peak tidal flow, which resulted in the asymmetry between neap-to-spring and spring-to-neap transitions. During the spring tide, a hysteresis loop was observed between shear stress and SSC, and its direction was different during flood and ebb tides. Although both fine sediments and flocs were dominant during flood tides, only fine sediments were noticed during ebb tides. Hence, the net elevation change in the bed was positive, and sedimentation took place during the semilunar tidal cycle. Finally, a bed of consolidated mud was deposited on the initial bed, and the height of the channel bed increased by 0.9 m during the two-week period. The observed hysteretic effect between shear stress and SSC during the spring tides, and the asymmetrical neap-spring-neap tidal cycle influenced the near-bed sediment dynamics of the channel, and led to the formation of a fluid mud layer at the bottom of the river.
Madej, Mary Ann; Bundros, Greg; Klein, Randy
2011-01-01
Revisions to the California Forest Practice Rules since 1974 were intended to increase protection of water quality in streams draining timber harvest areas. The effects of improved timber harvesting methods and road designs on sediment loading are assessed for the Panther Creek basin, a 15.4 km2 watershed in Humboldt County, north coastal California. We compute land use statistics, analyze suspended sediment discharge rating curves, and compare sediment yields in Panther Creek to a control (unlogged) stream, Little Lost Man Creek. From 1978 to 2008, 8.2 km2 (over half the watershed) was clearcut and other timber management activities (thinning, selection cuts, and so forth) affected an additional 5.9 km2. Since 1984, 40.7 km of streams in harvest units received riparian buffer strip protection. Between 2000 and 2009, 22 km of roads were upgraded and 9.7 km were decommissioned, reducing potential sediment production by an estimated 40,000 m3. Road density is currently 3.1 km/km2. Sediment rating curves from 2005 to 2010 indicate a decrease in suspended sediment concentrations when compared to the pre-1996 period, although Panther Creek still has a higher sediment yield on a per unit area basis than the control stream.
Baruch Institute for Marine and Coastal Sciences, Univ of South Carolina — A group of eight tidal creeks dominated by oysters, Crassostrea virginica, in North Inlet Estuary, South Carolina, USA were studied using a replicated BACI (Before -...
Ganju, N.K.; Bergamaschi, B.; Schoellhamer, D.H.
2003-01-01
Carbon and sediment fluxes from tidal wetlands are of increasing concern in the Sacramento-San Joaquin River Delta (Delta), because of drinking water issues and habitat restoration efforts. Certain forms of dissolved organic carbon (DOC) react with disinfecting chemicals used to treat drinking water, to form disinfection byproducts (DBPs), some of which are potential carcinogens. The contribution of DBP precursors by tidal wetlands is unknown. Sediment transport to and from tidal wetlands determines the potential for marsh accretion, thereby affecting habitat formation.Water, carbon, and sediment flux were measured in the main channel of Browns Island, a tidal wetland located at the confluence of Suisun Bay and the Delta. In-situ instrumentation were deployed between May 3 and May 21, 2002. Water flux was measured using acoustic Doppler current profilers and the index-velocity method. DOC concentrations were measured using calibrated ultraviolet absorbance and fluorescence instruments. Suspended-sediment concentrations were measured using a calibrated nephelometric turbidity sensor. Tidally averaged water flux through the channel was dependent on water surface elevations in Suisun Bay. Strong westerly winds resulted in higher water surface elevations in the area east of Browns Island, causing seaward flow, while subsiding winds reversed this effect. Peak ebb flow transported 36% more water than peak flood flow, indicating an ebb-dominant system. DOC concentrations were affected strongly by porewater drainage from the banks of the channel. Peak DOC concentrations were observed during slack after ebb, when the most porewater drained into the channel. Suspended-sediment concentrations were controlled by tidal currents that mobilized sediment from the channel bed, and stronger tides mobilized more sediment than the weaker tides. Sediment was transported mainly to the island during the 2-week monitoring period, though short periods of export occurred during the spring
Verschelling, Eelco; van der Deijl, Eveline; van der Perk, Marcel; Sloff, Kees; Middelkoop, Hans
2017-01-01
Sediment deposition is one of the key mechanisms to counteract the impact of sea level rise in tidal freshwater wetlands (TFWs). However, information about sediment deposition rates in TFWs is limited, especially for those located in the transition zone between the fluvially dominated and tidally
Turbidity and suspended sediment in the upper Esopus Creek watershed, Ulster County, New York
McHale, Michael R.; Siemion, Jason
2014-01-01
Suspended-sediment concentrations (SSCs) and turbidity were measured for 2 to 3 years at 14 monitoring sites throughout the upper Esopus Creek watershed in the Catskill Mountains of New York State. The upper Esopus Creek watershed is part of the New York City water-supply system that supplies water to more than 9 million people every day. Turbidity, caused primarily by high concentrations of inorganic suspended particles, is a potential water-quality concern because it colors the water and can reduce the effectiveness of drinking-water disinfection. The purposes of this study were to quantify concentrations of suspended sediment and turbidity levels, to estimate suspended-sediment loads within the upper Esopus Creek watershed, and to investigate the relations between SSC and turbidity. Samples were collected at four locations along the main channel of Esopus Creek and at all of the principal tributaries. Samples were collected monthly and during storms and were analyzed for SSC and turbidity in the laboratory. Turbidity was also measured every 15 minutes at six of the sampling stations with in situ turbidity probes.
Verschelling, Eelco; van der Deijl, Eveline; van der Perk, Marcel; Sloff, C.J.; Middelkoop, Hans
2017-01-01
Sediment deposition is one of the key mechanisms to counteract the impact of sea level rise in tidal freshwater wetlands (TFWs). However, information about sediment deposition rates in TFWs is limited, especially for those located in the transition zone between the fluvially dominated and tidally
DEFF Research Database (Denmark)
Madsen, Anni Tindahl; Murray, Andrew S.; Andersen, Thorbjørn Joest
2010-01-01
Depositional processes in intertidal areas are determined both by changes in sea-level and sediment supply. It is known on a millennial timescale that sedimentation normally keeps pace with sea-level rise in a subsiding tidal basin. However, little is known about whether the sedimentation can kee...
Stable isotope tracing of trout hatchery carbon to sediments and foodwebs of limestone spring creeks
Energy Technology Data Exchange (ETDEWEB)
Hurd, Todd M. [Department of Biology, Shippensburg University, 1871 Old Main Dr., Shippensburg, PA 17257 (United States)], E-mail: tmhurd@ship.edu; Jesic, Slaven; Jerin, Jessica L.; Fuller, Nathan W.; Miller, David [Department of Biology, Shippensburg University, 1871 Old Main Dr., Shippensburg, PA 17257 (United States)
2008-11-01
Limestone springs support productive ecosystems and fisheries, yet aquaculture may modify or impair these ecosystems. We determined trout hatchery organic contribution to spring creek sediments and foodwebs with natural abundance stable isotope methods. Hatchery feed, waste, and trout were significantly enriched in {delta}{sup 13}C relative to autotrophs and wild fish. Spring creek sediments were enriched in {delta}{sup 13}C toward the hatchery endmember relative to reference streams without hatcheries and relative to a larger larger-order, spring-influenced stream. Contribution of hatchery C to spring creek sediments was greatest during March and associated with greatest sediment %C. Contribution of hatchery C to pollution-tolerant isopod diet was 39-51% in a stream receiving limestone spring water via hatchery effluent. Isopods of one spring creek also relied on hatchery-derived C within one month of hatchery closure. Four years later, less pollution pollution-tolerant amphipods dominated and consumed non-vascular over vascular autotrophs (86%). Isopods of a second spring creek with an active hatchery did not appear to be using hatchery matter directly, but were enriched in {delta}{sup 34}S relative to a spring creek tributary with no hatchery influence. Isopods in both of these streams were relatively enriched in {delta}{sup 15}N, indicating general nutrient enrichment from surrounding agricultural land use. The contribution of hatchery vs. wild fish in diet of herons and egrets was traced with {delta}{sup 13}C of guano. These birds were strongly dependent on stocked trout in a spring creek with a recently closed state trout hatchery, and also near another large, state-run hatchery. Heron dependence on hatchery fish in the spring creek decreased with time since hatchery closure. Use of stable isotope natural abundance techniques in karst spring creeks can reveal stream impairment due to aquaculture, specific C sources to bio-indicating consumers, losses of
Stable isotope tracing of trout hatchery carbon to sediments and foodwebs of limestone spring creeks
International Nuclear Information System (INIS)
Hurd, Todd M.; Jesic, Slaven; Jerin, Jessica L.; Fuller, Nathan W.; Miller, David
2008-01-01
Limestone springs support productive ecosystems and fisheries, yet aquaculture may modify or impair these ecosystems. We determined trout hatchery organic contribution to spring creek sediments and foodwebs with natural abundance stable isotope methods. Hatchery feed, waste, and trout were significantly enriched in δ 13 C relative to autotrophs and wild fish. Spring creek sediments were enriched in δ 13 C toward the hatchery endmember relative to reference streams without hatcheries and relative to a larger larger-order, spring-influenced stream. Contribution of hatchery C to spring creek sediments was greatest during March and associated with greatest sediment %C. Contribution of hatchery C to pollution-tolerant isopod diet was 39-51% in a stream receiving limestone spring water via hatchery effluent. Isopods of one spring creek also relied on hatchery-derived C within one month of hatchery closure. Four years later, less pollution pollution-tolerant amphipods dominated and consumed non-vascular over vascular autotrophs (86%). Isopods of a second spring creek with an active hatchery did not appear to be using hatchery matter directly, but were enriched in δ 34 S relative to a spring creek tributary with no hatchery influence. Isopods in both of these streams were relatively enriched in δ 15 N, indicating general nutrient enrichment from surrounding agricultural land use. The contribution of hatchery vs. wild fish in diet of herons and egrets was traced with δ 13 C of guano. These birds were strongly dependent on stocked trout in a spring creek with a recently closed state trout hatchery, and also near another large, state-run hatchery. Heron dependence on hatchery fish in the spring creek decreased with time since hatchery closure. Use of stable isotope natural abundance techniques in karst spring creeks can reveal stream impairment due to aquaculture, specific C sources to bio-indicating consumers, losses of farmed fish to predation, and potential exposure
Morgan-King, Tara L.; Schoellhamer, David H.
2013-01-01
Backwater tidal sloughs are commonly found at the landward boundary of estuaries. The Cache Slough complex is a backwater tidal region within the Upper Sacramento–San Joaquin Delta that includes two features that are relevant for resource managers: (1) relatively high abundance of the endangered fish, delta smelt (Hypomesus transpacificus), which prefers turbid water and (2) a recently flooded shallow island, Liberty Island, that is a prototype for habitat restoration. We characterized the turbidity around Liberty Island by measuring suspended-sediment flux at four locations from July 2008 through December 2010. An estuarine turbidity maximum in the backwater Cache Slough complex is created by tidal asymmetry, a limited tidal excursion, and wind-wave resuspension. During the study, there was a net export of sediment, though sediment accumulates within the region from landward tidal transport during the dry season. Sediment is continually resuspended by both wind waves and flood tide currents. The suspended-sediment mass oscillates within the region until winter freshwater flow pulses flush it seaward. The hydrodynamic characteristics within the backwater region such as low freshwater flow during the dry season, flood tide dominance, and a limited tidal excursion favor sediment retention.
A coupled geomorphic and ecological model of tidal marsh evolution.
Kirwan, Matthew L; Murray, A Brad
2007-04-10
The evolution of tidal marsh platforms and interwoven channel networks cannot be addressed without treating the two-way interactions that link biological and physical processes. We have developed a 3D model of tidal marsh accretion and channel network development that couples physical sediment transport processes with vegetation biomass productivity. Tidal flow tends to cause erosion, whereas vegetation biomass, a function of bed surface depth below high tide, influences the rate of sediment deposition and slope-driven transport processes such as creek bank slumping. With a steady, moderate rise in sea level, the model builds a marsh platform and channel network with accretion rates everywhere equal to the rate of sea-level rise, meaning water depths and biological productivity remain temporally constant. An increase in the rate of sea-level rise, or a reduction in sediment supply, causes marsh-surface depths, biomass productivity, and deposition rates to increase while simultaneously causing the channel network to expand. Vegetation on the marsh platform can promote a metastable equilibrium where the platform maintains elevation relative to a rapidly rising sea level, although disturbance to vegetation could cause irreversible loss of marsh habitat.
International Nuclear Information System (INIS)
Walters, W.H.; Ecker, R.M.; Onishi, Y.
1982-11-01
A three-phase field sampling program was conducted on the Buttermilk-Cattaraugus Creek system to investigate the transport of radionuclides in surface waters as part of a continuing program to provide data for application and verification of Pacific Northwest Laboratory's (PNL) sediment and radionuclide transport model, SERATRA. Phase 1 of the sampling program was conducted during November and December 1977; Phase 2 during September 1978; and Phase 3 during April 1979. Bed sediment, suspended sediment, and water samples were collected over a 45-mile reach of the creek system. Bed sediment samples were also collected at the mouth of Cattaraugus Creek in Lake Erie. A fourth sampling trip was conducted during May 1980 to obtain supplementary channel geometry data and flood plain sediment samples. Radiological analysis of these samples included gamma ray spectrometry analysis, and radiochemical separation and analysis of Sr-90, Pu-238, Pu-239,240, Am-241 and Cm-244. Tritium analysis was also performed on water samples. Based on the evaluation of radionuclide levels in Cattaraugus and Buttermilk Creeks, the Nuclear Fuel Services facility at West Valley, New York, may be the source of Cs-137, Sr-90, CS-134, Co-60, Pu-238, Pu-239,240, Am-241, Cm-244 and tritium found in the bed sediment, suspended sediment and water of Buttermilk and Cattaraugus Creeks
Spatial and temporal distribution of 210Po in sediments from Thane Creek Mumbai, India
International Nuclear Information System (INIS)
Pandit, G.G.; Bhangare, R.C.; Tiwari, M.; Ajmal, P.Y.; Sahu, S.K.; Puranik, V.D.
2013-01-01
The study of sediments in coastal areas has great importance for the understanding of the interaction between human activities and marine systems. The Polonium-210 activity has been commonly used as environmental tracer in many environmental studies especially in determination of the age of sediments in the aquatic systems. The determination of age of the sediments provides the chronological profile of contamination of the marine environment over the period of time. The temporal and spatial distribution of 210 Po in Thane creek sediments was observed in this study. The allochthonous activity of 210 Po in surface sediments across different locations was observed to be the highest amongst different layers which ranged between 22.5-56.3 Bq/kg. The total 210 Po activity in different layers of the sediments ranged between 15.3 to 88.9 Bq/kg. The two modeling approaches CRS and CIC were applied to determine age of the sediment at four locations in the creek. (author)
Sediment transport and deposition on a river-dominated tidal flat: An idealized model study
Sherwood, Christopher R.; Chen, Shih-Nan; Geyer, W. Rockwell; Ralston, David K.
2010-01-01
A 3-D hydrodynamic model is used to investigate how different size classes of river-derived sediment are transported, exported and trapped on an idealized, river-dominated tidal flat. The model is composed of a river channel flanked by sloping tidal flats, a configuration motivated by the intertidal region of the Skagit River mouth in Washington State, United States. It is forced by mixed tides and a pulse of freshwater and sediment with various settling velocities. In this system, the river not only influences stratification but also contributes a significant cross-shore transport. As a result, the bottom stress is strongly ebb-dominated in the channel because of the seaward advance of strong river flow as the tidal flats drain during ebbs. Sediment deposition patterns and mass budgets are sensitive to settling velocity. The lateral sediment spreading scales with an advective distance (settling time multiplied by lateral flow speed), thereby confining the fast settling sediment classes in the channel. Residual sediment transport is landward on the flats, because of settling lag, but is strongly seaward in the channel. The seaward transport mainly occurs during big ebbs and is controlled by a length scale ratio Ld/XWL, where Ld is a cross-shore advective distance (settling time multiplied by river outlet velocity), and XWL is the immersed cross-shore length of the intertidal zone. Sediment trapping requires Ld/XWL stratification and reducing tidal range both favor sediment trapping, whereas varying channel geometries and asymmetry of tides has relatively small impacts. Implications of the modeling results on the south Skagit intertidal region are discussed.
Quantifying tidally driven benthic oxygen exchange across permeable sediments
DEFF Research Database (Denmark)
McGinnis, Daniel F.; Sommer, Stefan; Lorke, Andreas
2014-01-01
Continental shelves are predominately (approximate to 70%) covered with permeable, sandy sediments. While identified as critical sites for intense oxygen, carbon, and nutrient turnover, constituent exchange across permeable sediments remains poorly quantified. The central North Sea largely consists...... of permeable sediments and has been identified as increasingly at risk for developing hypoxia. Therefore, we investigate the benthic O-2 exchange across the permeable North Sea sediments using a combination of in situ microprofiles, a benthic chamber, and aquatic eddy correlation. Tidal bottom currents drive...... the variable sediment O-2 penetration depth (from approximate to 3 to 8 mm) and the concurrent turbulence-driven 25-fold variation in the benthic sediment O-2 uptake. The O-2 flux and variability were reproduced using a simple 1-D model linking the benthic turbulence to the sediment pore water exchange...
White Oak Creek embayment sediment retention structure: The Oak Ridge model in action
International Nuclear Information System (INIS)
Van Hoesen, S.D.; Kimmel, B.L.; Page, D.G.; Hudson, G.R.; Wilkerson, R.B.; Zocolla, M.
1992-01-01
White Oak Creek is the major surface-water drainage through the Department of Energy (DOE) Oak Ridge National Laboratory (ORNL). Samples taken from the lower portion of the creek revealed high levels of Cesium-137, and lower levels of Cobalt-60 in near-surface sediment. Other contaminants present in the sediment included: lead, mercury, chromium, and PCBS. In October 1990, DOE, US Environmental Protection Agency (EPA), and Tennessee Department of Environment and Conservation (DEC) agreed to initiate a time-critical removal action in accordance with Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) to prevent transport of the contaminated sediments into the Clinch River system. This paper discusses the environmental, regulatory, design, and construction issues that were encountered in conducting the remediation work
Sediment discharge division at two tidally influenced river bifurcations
Sassi, M.G.; Hoitink, A.J.F.; Vermeulen, B.; Hidayat, H.
2013-01-01
[1] We characterize and quantify the sediment discharge division at two tidally influenced river bifurcations in response to mean flow and secondary circulation by employing a boat-mounted acoustic Doppler current profiler (ADCP), to survey transects at bifurcating branches during a semidiurnal
On the Sediment Dynamics in a Tidally Energetic Channel: The Inner Sound, Northern Scotland
Directory of Open Access Journals (Sweden)
Jason McIlvenny
2016-04-01
Full Text Available Sediment banks within a fast-flowing tidal channel, the Inner Sound in the Pentland Firth, were mapped using multi-frequency side-scan sonar. This novel technique provides a new tool for seabed sediment and benthic habitat mapping. The sonar data are supplemented by sediment grab and ROV videos. The combined data provide detailed maps of persistent sand and shell banks present in the Sound despite the high energy environment. Acoustic Doppler Current Profiler (ADCP data and numerical model predictions were used to understand the hydrodynamics of the system. By combining the hydrodynamics and sediment distribution data, we explain the sediment dynamics in the area. Sediment particle shape and density, coupled with persistent features of the hydrodynamics, are the key factors in the distribution of sediment within the channel. Implications for tidal energy development planned for the Sound are discussed.
Contaminant characterization of sediment and pore-water in the Clinch River and Poplar Creek
International Nuclear Information System (INIS)
Levine, D.A.; Harris, R.A.; Campbell, K.R.; Hargrove, W.W.; Rash, C.D.
1995-01-01
Sediment and pore-water samples were collected from 80 locations in the Clinch River and Poplar Creek system to characterize concentrations and spatial distribution of contaminants for use in ecological risk assessment. Sediment cores were collected at each site and the top 15 cm was analyzed to represent the biologically active zone. Sediment for pore-water extraction was collected in large volumes using a Ponar grab sampler. Pore-water was extracted from this sediment using centrifugation, All samples were analyzed for metals (including methyl mercury), organics, and radiological constituents. Additionally, sediment was analyzed for physical properties: particle size distribution, density, and porosity. Sediment and pore-water were also analyzed for total organic carbon and nitrogen and ammonia levels. Sediment and pore-water were also analyzed for total organic carbon and nitrogen and ammonia levels. Sediment and pre-water results indicate that there are several areas where concentrations of a variety of contaminants are high enough to causes ecological effects. These locations in the river are immediately downstream from know sources of Contamination from on-site DOE facilities. East Fork Poplar Creek is a source of several metals, including mercury, cadmium, chromium, and copper. Mitchell Branch is a source of number of metals, uranium isotopes, technetium-99, and several PAHs. There are two clear sources of arsenic and selenium to the system, one in Poplar Creek and one in Melton Hill Reservoir, both related to past disposal of coal-ash. High concentrations in sediments did not always coincide with high concentrations in pore-water for the same sites and contaminants. This appears to be related to particle size of the sediment and total organic carbon
Guimond, J. A.; Yu, X.; Duque, C.; Michael, H. A.
2016-12-01
Salt marshes are a hydrologically complex ecosystem. Tides deliver saline surface water to salt marshes via tidal creeks, and freshwater is introduced through lateral groundwater flow and vertical infiltration from precipitation. Locally, sediment heterogeneity, tides, weather, and topography introduce spatial and temporal complexities in groundwater-surface water interactions, which, in turn, can have a large impact on salt marsh biogeochemistry and the lateral fluxes of nutrients and carbon between the marsh platform and tidal creek. In this study, we investigate spatial patterns of porewater fluorescent dissolved organic matter (fDOM) and redox potential over a spring-neap tidal cycle in a mid-latitude tidal salt marsh in Dover, Delaware. Porewater samplers were used in conjunction with a peristaltic pump and YSI EXO Sonde to measure porewater fDOM, electrical conductivity, redox potential and pH from 0.5, 1.0, 1.5, 2.0, and 2.3 meters deep, as well as surface water from the creek and marsh platform. Eh was also measured continuously every 15 minutes with multi-level in-situ redox sensors at 0, 3, and 5m from the tidal creek, and water level and salinity were measured every 15 minutes continuously in 6 wells equipped with data loggers. Preliminary analyses indicate porewater salinity is dependent on the slope of the marsh platform, the elevation of the sample location, and the distance from a tidal creek. Near-creek redox analyses show tidal oscillations up to 300 mV; redox oscillations in the marsh interior show longer timescale changes. The observed redox oscillations coincide with the water level fluctuations at these locations. Therefore, lateral transport of carbon is determined by both hydrologic flow and biogeochemical processes. Results from this study provide insight into the timescales over which salt marsh hydrology impacts porewater biogeochemistry and the mechanisms controlling regional carbon cycling.
DEFF Research Database (Denmark)
Fruergaard, M.; Andersen, T.J.; Nielsen, L.H.
2011-01-01
depositional environment, but tidal channel sediments dominate in the five sediment cores, making up 56% of the 15 mof sediment core. Sedimentation in the lagoon alternated between slow vertical aggradation of sand flats (1.5–2 mm yr-1) and very fast lateral progradation of point bars in tidal channels, which...... caused the formation of a punctuated lagoonal fill. Frequent and comprehensive reworking of the sand flat sediments by tidal channel migration entails loss of sedimentary structures and bioturbation related to sand flat deposits, and old sand flat sediments are only very sparsely preserved. We further...... conclude that long-term (millennial timescale) sediment accumulation in the lagoon was controlled by rising sea-level, whereas short-term (centurial timescale) sediment accumulation was controlled by local erosion and depositional events caused by lateral migration of channels. Records of short-term sea...
Suspended-sediment dynamics in the tidal reach of a San Francisco Bay tributary
Shellenbarger, Gregory; Downing-Kunz, Maureen; Schoellhamer, David H.
2015-01-01
To better understand suspended-sediment transport in a tidal slough adjacent to a large wetland restoration project, we deployed continuously measuring temperature, salinity, depth, turbidity, and velocity sensors in 2010 at a near-bottom location in Alviso Slough (Alviso, California, USA). Alviso Slough is the downstream reach of the Guadalupe River and flows into the far southern end of San Francisco Bay. River flow is influenced by the Mediterranean climate, with high flows (∼90 m3 s−1) correlated to episodic winter storms and low base flow (∼0.85 m3 s−1) during the summer. Storms and associated runoff have a large influence on sediment flux for brief periods, but the annual peak sediment concentrations in the slough, which occur in April and May, are similar to the rest of this part of the bay and are not directly related to peak discharge events. Strong spring tides promote a large upstream sediment flux as a front associated with the passage of a salt wedge during flood tide. Neap tides do not have flood-directed fronts, but a front seen sometimes during ebb tide appears to be associated with the breakdown of stratification in the slough. During neap tides, stratification likely suppresses sediment transport during weaker flood and ebb tides. The slough is flood dominant during spring tides, and ebb dominant during neap tides. Extreme events in landward (salt wedge) and bayward (rainfall events) suspended-sediment flux account for 5.0 % of the total sediment flux in the slough and only 0.55 % of the samples. The remaining 95 % of the total sediment flux is due to tidal transport, with an imbalance in the daily tidal transport producing net landward flux. Overall, net sediment transport during this study was landward indicating that sediment in the sloughs may not be flushed to the bay and are available for sedimentation in the adjacent marshes and ponds.
Mercury Content of Sediments in East Fork Poplar Creek: Current Assessment and Past Trends
Energy Technology Data Exchange (ETDEWEB)
Brooks, Scott C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eller, Virginia A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dickson, Johnbull O. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Earles, Jennifer E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lowe, Kenneth Alan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mehlhorn, Tonia L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Olsen, Todd A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); DeRolph, Christopher R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Watson, David J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Phillips, Debra H. [Queen' s Univ., Belfast (United Kingdom); Peterson, Mark J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2017-01-01
This study provided new information on sediment mercury (Hg) and monomethylmercury (MMHg) content and chemistry. The current inventory of Hg in East Fork Poplar Creek (EFPC) bed sediments was estimated to be 334 kg, which represents a ~67% decrease relative to the initial investigations in 1984. MMHg sediment inventory was estimated to be 44.1 g, lower but roughly similar to past estimates. The results support the relevance and potential impacts of other active and planned investigations within the Mercury Remediation Technology Development for Lower East Fork Poplar Creek project (e.g., assessment and control of bank soil inputs, sorbents for Hg and MMHg removal, re-introduction of freshwater clams to EFPC), and identify gaps in current understanding that represent opportunities to understand controlling variables that may inform future technology development studies.
Determination of sedimentation rate in Thane creek using 210Pb dating
International Nuclear Information System (INIS)
Sahu, S.K.; Bhangare, R.C.; Ajmal, P.Y; Tiwari, M.; Pandit, G.G.; Puranik, V.D.
2012-01-01
Sediments are good representatives of the geochemical history of a particular area. They can be regarded as good archives of environmental processes and their effects. Therefore, the study of sediments in coastal areas has great importance for the understanding of the interaction between human activities and marine systems. The sedimentation process can be correlated with time by assessing decays of radionuclides like 210 Pb, 137 Cs and 14 C in different layers of it. 210 Pb and its environmental cycle have been commonly used as environmental tracer in many environmental studies. For assessment of chronological history of pollution in the Mumbai region, sediment samples were collected from Thane creek and sedimentation rates were estimated by measurement of 210 Po activity which is in equilibrium with 210 Pb
Directory of Open Access Journals (Sweden)
K. Hanegan
2015-03-01
Full Text Available In this study, a Delft3D model of the Wax Lake Delta was developed to simulate flow and sediment flux through delta distributary channels. The model was calibrated for tidal constituents as well as velocity and sediment concentration across channel transects. The calibrated model was then used to simulate full spring–neap tidal cycles under constant low flow upstream boundary conditions, with grain size variation in suspended load represented using two sediment fractions. Flow and sediment flux results through distributary channel cross-sections were examined for spatial and temporal variability with the goal of characterizing the role of tides in sediment reworking and delta development. The Wax Lake Delta has prograded through channel extension, river mouth bar deposition, and channel bifurcation. Here we show that tidal modulation of currents influences suspended sand transport, and spatial acceleration through distributary channels at low tides is sufficient to suspend sand in distal reaches during lower flows. The basinward-increasing transport capacity in distributary channels indicates that erosive channel extension could be an important process, even during non-flood events.
Erikson, Li H.; Wright, Scott A.; Elias, Edwin; Hanes, Daniel M.; Schoellhamer, David H.; Largier, John; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.
2013-01-01
Sediment exchange at large energetic inlets is often difficult to quantify due complex flows, massive amounts of water and sediment exchange, and environmental conditions limiting long-term data collection. In an effort to better quantify such exchange this study investigated the use of suspended sediment concentrations (SSC) measured at an offsite location as a surrogate for sediment exchange at the tidally dominated Golden Gate inlet in San Francisco, CA. A numerical model was calibrated and validated against water and suspended sediment flux measured during a spring–neap tide cycle across the Golden Gate. The model was then run for five months and net exchange was calculated on a tidal time-scale and compared to SSC measurements at the Alcatraz monitoring site located in Central San Francisco Bay ~ 5 km from the Golden Gate. Numerically modeled tide averaged flux across the Golden Gate compared well (r2 = 0.86, p-value
Stogner, Sr., Robert W.; Nelson, Jonathan M.; McDonald, Richard R.; Kinzel, Paul J.; Mau, David P.
2013-01-01
In 2008, the U.S. Geological Survey (USGS), in cooperation with Pikes Peak Area Council of Governments, Colorado Water Conservation Board, Colorado Springs City Engineering, and the Lower Arkansas Valley Water Conservancy District, began a small-scale pilot study to evaluate the effectiveness of the use of a computational model of streamflow and suspended-sediment transport for predicting suspended-sediment concentrations and loads in the Fountain Creek watershed in Colorado. Increased erosion and sedimentation damage have been identified by the Fountain Creek Watershed Plan as key problems within the watershed. A recommendation in the Fountain Creek Watershed plan for management of the basin is to establish measurable criteria to determine if progress in reducing erosion and sedimentation damage is being made. The major objective of this study was to test a computational method to predict local suspended-sediment loads at two sites with different geomorphic characteristics in order to evaluate the feasibility of using such an approach to predict local suspended-sediment loads throughout the entire watershed. Detailed topographic surveys, particle-size data, and suspended-sediment samples were collected at two gaged sites: Monument Creek above Woodmen Road at Colorado Springs, Colorado (USGS gage 07103970), and Sand Creek above mouth at Colorado Springs, Colorado (USGS gage 07105600). These data were used to construct three-dimensional computational models of relatively short channel reaches at each site. The streamflow component of these models predicted a spatially distributed field of water-surface elevation, water velocity, and bed shear stress for a range of stream discharges. Using the model predictions, along with measured particle sizes, the sediment-transport component of the model predicted the suspended-sediment concentration throughout the reach of interest. These computed concentrations were used with predicted flow patterns and channel morphology to
International Nuclear Information System (INIS)
Onishi, Y.; Yabusaki, S.B.; Kincaid, C.T.; Skaggs, R.L.; Walters, W.H.
1982-12-01
SERATRA, a transient, two-dimensional (laterally-averaged) computer model of sediment-contaminant transport in rivers, satisfactorily resolved the distribution of sediment and radionuclide concentrations in the Cattaraugus Creek stream system in New York. By modeling the physical processes of advection, diffusion, erosion, deposition, and bed armoring, SERATRA routed three sediment size fractions, including cohesive soils, to simulate three dynamic flow events. In conjunction with the sediment transport, SERATRA computed radionuclide levels in dissolved, suspended sediment, and bed sediment forms for four radionuclides ( 137 Cs, 90 Sr, 239 240 Pu, and 3 H). By accounting for time-dependent sediment-radionuclide interaction in the water column and bed, SERATA is a physically explicit model of radionuclide fate and migration. Sediment and radionuclide concentrations calculated by SERATA in the Cattaraugus Creek stream system are in reasonable agreement with measured values. SERATRA is in the field performance phase of an extensive testing program designed to establish the utility of the model as a site assessment tool. The model handles not only radionuclides but other contaminants such as pesticides, heavy metals and other toxic chemicals. Now that the model has been applied to four field sites, including the latest study of the Cattaraugus Creek stream system, it is recommended that a final model be validated through comparison of predicted results with field data from a carefully controlled tracer test at a field site. It is also recommended that a detailed laboratory flume be tested to study cohesive sediment transport, deposition, and erosion characteristics. The lack of current understanding of these characteristics is one of the weakest areas hindering the accurate assessment of the migration of radionuclides sorbed by fine sediments of silt and clay
Castellanos-Galindo, G. A.; Krumme, U.
2014-08-01
Intertidal fish assemblages are thought to respond to tidal and diel rhythms although the assumption that these patterns are stable over long time scales (>1 year) is largely untested. Testing the validity of this assumption is necessary to assess whether short-term temporal patterns, once established, can be extrapolated over time and give a better understanding of the temporal dynamics of fish assemblages in coastal habitats. Here, we compare the fish assemblage structure from two intertidal mangrove creeks in North Brazil (Bragança Peninsula, Caeté estuary) sampled with the same sampling methodology (block nets), effort (two lunar cycles) and design (accounting for the combination of tidal and diel cycle) in the rainy seasons of 1999 and 2012 to evaluate the persistence, stability and recurrence of short-term patterns in the fish community organization. The interaction of tidal and diel cycles (inundations at spring tide-night, spring tide-day, neap tide-night, neap tide-day), found to be stable after 13 years, resulted in recurrent and stable intertidal mangrove fish assemblage compositions. The intertidal mangrove creek fish assemblage consisted of a persistent number of dominant species (seven). However, there were notable changes in fish catch mass, abundance and species dominance between 1999 and 2012. The most severe drought in North Brazil in 30 years, linked to lower precipitation and river runoff in the rainy season of 2012, may have resulted in (1) lower abundance of small juveniles of several dominant species in this assemblage (especially Ariidae - Cathorops agassizii and Sciades herzbergii) and (2) increased dominance of large-sized specimens of the tetraodontid Colomesus psittacus. Our findings highlight: (1) the overriding importance and stability of the interactive pulse of the tidal and diel cycles in determining short-term temporal patterns in intertidal mangrove fish assemblages in neotropical macrotidal estuaries despite the occurrence of
Heimann, David C.; Richards, Joseph M.
2003-01-01
The Squaw Creek National Wildlife Refuge (hereafter referred to as the Refuge), located on the Missouri River floodplain in northwest Missouri, was established in 1935 to provide habitat for migratory birds and wildlife. Results of 1937 and 1964 topographic surveys indicate that sedimenta-tion, primarily from Squaw Creek and Davis Creek inflows, had substantially reduced Refuge pool volumes and depths. A study was undertaken by the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, to quantify and spatially analyze historic rates of sedimentation in the Refuge and determine the surface elevations, depths, and pool capacities for selected managed pools from a 2002 survey.The 1937 to 1964 mean total sediment depo-sition, in the area corresponding to the 2002 sur-veyed pool area (about 4,900 acres), was 1.26 ft (feet), or 0.047 ft/yr (foot per year). Mean annual rates of deposition, by pool, from 1937 to 1964 varied from 0.016 to 0.083 ft/yr. From 1964 to 2002, the mean total sediment deposition in the 2002 surveyed pools was 0.753 ft, or 0.020 ft/yr. Therefore, the mean rate of sediment-depth accu-mulation from 1964 to 2002 was about 42 percent of the mean 1937 to 1964 rate, or a 58 percent reduction. Mean annual rates of deposition by pool from 1964 to 2002 varied from 0.010 to 0.049 ft/yr. Despite a substantial reduction in the average sediment accumulation rate for the Refuge, 5 of the 15 separate pools for which annual rates were calculated for both periods showed a small increase in the deposition rates of up to 0.008 ft/yr. Sediment deposits have resulted in a sub-stantial cumulative loss of volume in the Refuge pools since 1937. The 1937 to 2002 total sediment volume deposited in the 2002 surveyed pool area was about 9,900 acre-ft (acre-feet), or 152 acre-ft/yr (acre-feet per year). The volume of sediment deposited from 1937 to 1964 for these pools was about 6,200 acre-ft, or 230 acre-ft/yr. The volume deposited from 1964 to 2002
Tidal and longshore sediment transport associated to a coastal structure
Cuadrado, Diana G.; Gómez, Eduardo A.; Ginsberg, S. Susana
2005-01-01
In order to understand the subtidal marine dynamics relative to the coastal engineering works in the Bahía Blanca Estuary (Argentina), the balance of sediment transport caused by tidal currents was estimated in the Puerto Rosales area and compared with the predicted potential littoral transport. The breaking wave height used in the littoral drift calculation was estimated after applying different wave transforming procedures over the deepwater wave which was predicted by the occurrence of predominant wind, blowing long enough in an essentially constant direction over a fetch. The effect of a breakwater on currents and circulation was studied by bathymetric and side-scan sonar records, sedimentology, and tidal current measurements. Different modes of transport occur on either sides of the breakwater. On the east side, longshore transport is the principal mode, and on the west side, tidal transport is predominant.
International Nuclear Information System (INIS)
Homer, M.
1976-01-01
Monthly measurements were made of the seasonal abundance, biomass, species diversity, and trophic composition of fish inhabiting the tidal creeks of salt marshes receiving thermal discharge near Crystal River, Fla. In the warm months (May through September 1974), mean abundance in the creek receiving thermal discharge was 0.46 individuals/m 2 and mean biomass was 2.2 g (preserved weight)/m 2 . In a control area, creek values in the warm months were 6.77 individuals/m 2 and 9.1 g (preserved weight)/m 2 , respectively. During the cold months (October 1974 through February 1975) there were 0.48 individuals/m 2 and 8.3 g (preserved weight)/m 2 in the discharge area and 0.58 individuals/m 2 and 7.4 g preserved weight/m 2 in the control area. In all months except May 1974 and February 1975, species diversity as species per 1000 individuals was higher in the control creek than in the discharge creek. No apparent differences in fish trophic structure were observed
The role of seasonal sediment storage in tidal channels on a mesotidal delta
Hale, R. P.; Wilson, C.; Bomer, J.; Goodbred, S. L., Jr.; Bain, R. L.
2017-12-01
The Sundarbans National Forest (SNF), located on the modern topset of the Ganges-Brahmaputra-Meghna (GBM) Delta, is the world's largest mangrove stand ( 10,000 km2), and provides a wide range of cultural, environmental, and economic benefits to the nation of Bangladesh. At present, sediment accretion in the SNF occurs at a rate comparable to that of the locally accelerated sea-level rise ( 1.1 cm/yr), despite substantial modification of the regional hydrodynamics via the construction of channel embankments to prevent inundation of agricultural areas. Approximately 50% of the sediment deposited in the SNF each year is recently delivered (water diversions associated with India's National River Linking Project raises serious concerns over the SNF's continued sustainability. Here, we examine: 1) the capacity for short-term sediment storage within tidal channels of varying dimensions, and 2) the hydrodynamic conditions responsible for resuspending this material and delivering it to the mangrove platform. We compare textural and radiochemical characteristics from short cores (<50 cm) collected along the intertidal channel banks, with those from the mangrove platform, to assess seasonal storage of GBM sediment within tidal channels, and the timeframe of its delivery to the SNF platform. We also present instrument data from multiple locations within a confined basin of the SNF, using an upward-looking acoustic Doppler current profiler, pressure sensors, and optical backscatter sensors, to document how transport conditions vary with distance away from the primary tidal inlet, and across the platform. This collection of physical and instrumental observations is then compared to an existing dataset of platform inundation hydroperiods and deposition rates, allowing us to address the threat of a reduced sediment supply to this region, as well as the capacity for this system to self-supply sediment to the platform.
Van de Broek, Marijn; Vandendriessche, Caroline; Poppelmonde, Dries; Merckx, Roel; Temmerman, Stijn; Govers, Gerard
2018-02-12
Tidal marshes are vegetated coastal ecosystems that are often considered as hotspots of atmospheric CO 2 sequestration. Although large amounts of organic carbon (OC) are indeed being deposited on tidal marshes, there is no direct link between high OC deposition rates and high OC sequestration rates due to two main reasons. First, the deposited OC may become rapidly decomposed once it is buried and, second, a significant part of preserved OC may be allochthonous OC that has been sequestered elsewhere. In this study we aimed to identify the mechanisms controlling long-term OC sequestration in tidal marsh sediments along an estuarine salinity gradient (Scheldt estuary, Belgium and the Netherlands). Analyses of deposited sediments have shown that OC deposited during tidal inundations is up to millennia old. This allochthonous OC is the main component of OC that is effectively preserved in these sediments, as indicated by the low radiocarbon content of buried OC. Furthermore, OC fractionation showed that autochthonous OC is decomposed on a decadal timescale in saltmarsh sediments, while in freshwater marsh sediments locally produced biomass is more efficiently preserved after burial. Our results show that long-term OC sequestration is decoupled from local biomass production in the studied tidal marsh sediments. This implies that OC sequestration rates are greatly overestimated when they are calculated based on short-term OC deposition rates, which are controlled by labile autochthonous OC inputs. Moreover, as allochthonous OC is not sequestered in-situ, it does not contribute to active atmospheric CO 2 sequestration in these ecosystems. A correct assessment of the contribution of allochthonous OC to the total sedimentary OC stock in tidal marsh sediments as well as a correct understanding of the long-term fate of locally produced OC are both necessary to avoid overestimations of the rate of in-situ atmospheric CO 2 sequestration in tidal marsh sediments. © 2018 John
Horstman, Erik; Dohmen-Janssen, Catarine M.; Bouma, T.J.; Hulscher, Suzanne J.M.H.
2015-01-01
Tidal-scale biophysical interactions establish particular flow routing and sedimentation patterns in coastal mangroves. Sluggish water flows through the mangrove vegetation and enhanced sediment deposition are essential to maintain these valuable ecosystems, thereby enabling their contribution to
Kohn, Michael S.; Fulton, John W.; Williams, Cory A.; Stogner, Sr., Robert W.
2014-01-01
The U.S. Geological Survey (USGS) in cooperation with the Fountain Creek Watershed, Flood Control and Greenway District assessed remediation scenarios to attenuate peak flows and reduce sediment loads in the Fountain Creek watershed. To evaluate these strategies, the U.S. Army Corps of Engineers Hydrologic Engineering Center (HEC) hydrologic and hydraulic models were employed. The U.S. Army Corps of Engineers modeling system HEC-HMS (Hydrologic Modeling System) version 3.5 was used to simulate runoff in the Fountain Creek watershed, Colorado, associated with storms of varying magnitude and duration. Rain-gage precipitation data and radar-based precipitation data from the April 28–30, 1999, and September 14–15, 2011, storm events were used in the calibration process for the HEC-HMS model. The curve number and lag time for each subwatershed and Manning's roughness coefficients for each channel reach were adjusted within an acceptable range so that the simulated and measured streamflow hydrographs for each of the 12 USGS streamgages approximated each other. The U.S. Army Corps of Engineers modeling system HEC-RAS (River Analysis System) versions 4.1 and 4.2 were used to simulate streamflow and sediment transport, respectively, for the Fountain Creek watershed generated by a particular storm event. Data from 15 USGS streamgages were used for model calibration and 7 of those USGS streamgages were used for model validation. The calibration process consisted of comparing the simulated water-surface elevations and the cross-section-averaged velocities from the model with those surveyed in the field at the cross section at the corresponding 15 and 7 streamgages, respectively. The final Manning’s roughness coefficients were adjusted between –30 and 30 percent at the 15 calibration streamgages from the original left, right, and channel-averaged Manning's roughness coefficients upon completion of calibration. The U.S. Army Corps of Engineers modeling system HEC
International Nuclear Information System (INIS)
Ecker, R.M.; Walters, W.H.; Onishi, Y.
1982-08-01
A field sampling program was conducted on Cattaraugus and Buttermilk Creeks, New York during April 1979 to investigate the transport of radionuclides in surface waters as part of a continuing program to provide data for application and verification of Pacific Northwest Laboratory's (PNL) sediment and radionuclide transport model, SERATRA. Bed sediment, suspended sediment and water samples were collected during unsteady flow conditions over a 45 mile reach of stream channel. Radiological analysis of these samples included gamma ray spectrometry analysis, and radiochemical separation and analysis of Sr-90, Pu-238, Pu-239, 240, Am-241 and Cm-244. Tritium analysis was also performed on water samples. Based on the evaluation of radionuclide levels in Cattaraugus and Buttermilk Creeks, the Nuclear Fuel Services facility at West Valley, New York, may be the source of Cs-137, Sr-90, Cs-134, Co-60, Pu-238, Pu-239, 240, Am-241, Cm-244 and tritium found in the bed sediment, suspended sediment and water of Buttermilk and Cattaraugus Creeks. This field sampling effort was the last of a three phase program to collect hydrologic and radiologic data at different flow conditions
Macavoy, S. E.; Garman, G. C.
2006-12-01
Coastal freshwater streams are typically viewed as conduits for the transport of sediment and nutrients to the coasts. Some coastal streams however experience seasonal migrations of anadromous fish returning to the freshwater to spawn. The fish may be vectors for the delivery of marine nutrients to nutrient poor freshwater in the form of excreted waste and post-spawning carcasses. Nutrients derived from marine sources are 13C, 15N and 34S enriched relative to nutrients in freshwater. Here we examine sediment, particulate organic matter (POM), invertebrates and fish in two tidal freshwater tributaries of the James River USA. The d15N of POM became elevated (from 3.8 to 6.5%), coincident with the arrival of anadromous river herring (Alosa sp), indicating a pulse of marine nitrogen. However, the elevated 15N was not observed in sediment samples or among invertebrates, which did not experience a seasonal isotopic shift (there were significant differences however among the guilds of invertebrate). Anadromous Alosa aestivalis captured within the tidal freshwater were 13C and 34S enriched (-19.3 and 17.2%, respectively) relative to resident freshwater fishes (-26.4 and 3.6% respectively) captured within 2 weeks of the Alosa. Although it is likely that marine derived nitrogen was detected in the tidal freshwater, it was not in sufficient abundance to change the isotope signature of most ecosystem components.
International Nuclear Information System (INIS)
Soucek, D.J.; Currie, R.J.; Cherry, D.S.; Latimer, H.A.
1998-01-01
The Ely Creek watershed in Lee County, Virginia, contains an abundance of abandoned mined land (AML) seeps that contaminate the majority of the creek and its confluence into Big Stone Creek. Contaminated sediments had high concentrations of iron (∼10,000 mg/kg), aluminum (∼1,500 mg/kg), magnesium (∼400 mg/kg) and manganese (∼150 mg/kg). Copper and zinc generally ranged from 3 to 20 mg/kg. Benthic macroinvertebrates surveys at six of 20 sites sampled in the watershed yielded no macroinvertebrates, while eight others had total abundances of 1 to 9 organisms. Four reference sites contained ≥100 organisms and at least 14 different taxa. Laboratory, 10-day survival/impairment sediments tests with Daphnia magna did not support the field data. Mortality of 92 to 100% for D. magna occurred in samples collected from six cities. Daphnid reproduction was more sensitive than laboratory test organism survivorship; however, neither daphnid survivorship nor reproduction were good predictors of taxa richness. Laboratory test concerns included the use of a reference diluent water rather than site specific diluent water
Huijts, K.M.H.|info:eu-repo/dai/nl/304831867; de Swart, H.E.|info:eu-repo/dai/nl/073449725; Schramkowski, G.P.; Schuttelaars, H.M.
2011-01-01
An analytical and a numerical model are used to understand the response of velocity and sediment distributions over Gaussian-shaped estuarine cross-sections to changes in tidal forcing and water depth. The estuaries considered here are characterized by strong mixing and a relatively weak
Michael Brent Napolitano
1996-01-01
Abstract - The old-growth redwood forest of North Fork Caspar Creek was clear-cut between 1864 and 1904. Previous research on logging-related changes in suspended sediment and streamflow would suggest that North Fork Caspar Creek has recovered from historical logging (Rice et al., 1979; Ziemer, 1981); research on the influence of large woody debris (LWD) on channel...
Jones, Chance E; Maddox, Anthony; Hurley, Dorset; Barkovskii, Andrei L
2018-05-19
Intertidal creeks form the primary hydrologic link between estuaries and land-based activities on barrier islands. Fecal indicators Enterococcus spp. (Entero1), pathogens Shigella spp. (ipaH), Salmonella spp. (invA), E. coli of EHEC/EPEC groups (eaeA), E. coli of EAEC, EIEC, and UPEC groups (set1B), E. coli of STEC group (stx1); and tetracycline resistance genes (tet(B), tet(C), tet(D), tet(E), tet(K), tet(Q), tet(W), and tet(X); TRG) were detected in the headwater of Oakdale Creek (Sapelo Island, GA) receiving runoffs from Hog Hammock village. Excavation of drainage ditches around the village caused a high increase in the incidence of the above determinants. Water samples were collected from the headwater, transferred to diffusion chambers, submersed in the headwater, saltmarsh, and mouth of the creek; and the determinants were monitored for 3 winter months. With some exceptions, their persistence decreased in order headwater > saltmarsh > mouth. Genes associated with Enterococcus spp. were the most persistent at all the sites, following in the headwater with determinants for Salmonella spp. and E. coli of EAEC, EIEC, and UPEC groups. In the mouth, the most persistent gene was eaeA indicating EHEC, EPEC, and STEC. Tet(B) and tet(C) persisted the longest in headwater and saltmarsh. No TRG persisted after 11 days in the mouth. Most determinants revealed correlations with temperature and pH, and inverse correlations with dissolved oxygen. Decay rates of the above determinants varied in the range of -0.02 to -0.81/day, and were up to 40 folds higher in the saltmarsh and mouth than in the headwater. Our data demonstrated that water parameters could to some extent predict a general trend in the fate of virulence and antibiotic resistance determinants in tidal creek tributaries but strongly suggested that their persistence in these tributaries cannot be predicted from that of enterococci, or extrapolated from one biological contaminant to another. Copyright
Baruch Institute for Marine and Coastal Sciences, Univ of South Carolina — The CREEK Project began in January of 1996 and was designed to help determine the role of oysters, Crassostrea virginica, in tidal creeks of the North Inlet Estuary,...
Biogenic silica in tidal freshwater marsh sediments and vegetation (Schelde estuary, Belgium)
Struyf, E.; van Damme, S.; Gribsholt, B.; Middelburg, J.J.; Meire, P.
2005-01-01
To date, estuarine ecosystem research has mostly neglected silica cycling in freshwater intertidal marshes. However, tidal marshes can store large amounts of biogenic silica (BSi) in vegetation and sediment. BSi content of the typical freshwater marsh plants Phragmites australis, Impatiens
The Influence of Water Circulation on Dissolved Organic Matter Dynamics in Bald Head Creek
Lebrasse, M. C.; Osburn, C. L.; Bohnenstiehl, D. R.; He, R.
2016-12-01
Dissolved organic matter (DOM) plays an important role in biogeochemical cycles in estuaries such as tidal creeks draining coastal wetlands such as salt marshes. However, significant knowledge gaps remain regarding the quantity and quality of the DOM that tidally exchanges between salt marshes and their adjacent estuaries. Tidal movements play a central role in lateral exchanges of materials and bidirectional flow results in the mixing of DOM from marsh plants and estuarine DOM. The aim of this study was to better understand the role of water circulation on the distribution and quality of DOM in Bald Head Creek, a tributary to the Cape Fear River estuary in eastern North Carolina. Dissolved organic carbon (DOC) concentration, stable carbon isotopes, and chromophoric DOM (CDOM) absorbance at 254 nm (a254) were used to distinguish between DOM quantity and quality at three locations along the creek: Site 3 (upstream), Site 2 (middle stream), and Site 1 (near the creek mouth). Samples were collected over four tidal cycles between March-August 2016 and compared to time series data collected approximately weekly from 2014-2016. DOM characteristics differed substantially over the tidal cycle. Higher CDOM and DOC concentration were observed at low tide than at high tide at all three sites, suggesting greater export of carbon from the marsh into the creek as the tides recede. Analysis of CDOM quality based on specific UV absorbance at 254 nm (SUVA254) and spectral slope ratio (SR) showed that the marsh end-member (Site 3) source of DOM had greater aromaticity and higher molecular weight. Site 1 showed greater variability over the tidal cycle most likely due to a greater tidal influence, being closer to the mouth. Additionally, an unmanned surface vehicle (USV) and a hydrodynamic model were used to map water circulation and DOC concentration along the creek to compute exchanges with the adjacent estuary. Results suggest that estuarine OM dynamics are strongly controlled by
Currents and siltation at Dharamtar creek, Bombay
Digital Repository Service at National Institute of Oceanography (India)
Swamy, G.N.; Kolhatkar, V.M.; Fernandes, A.A.
Hydrographic data collected in Dharamtar Creek during 1976-77 have been analysed. This showed that the waters in the Creek are well mixed and the salinity varied with the tide. The tidal currents are found to be generally strong. The distribution...
Directory of Open Access Journals (Sweden)
Maria eFabisch
2013-12-01
Full Text Available We identified and quantified abundant iron-oxidizing bacteria (FeOB at three iron-rich, metal-contaminated creek sites with increasing sediment pH from extremely acidic (R1, pH 2.7, to moderately acidic (R2, pH 4.4, to slightly acidic (R3, pH 6.3 in a former uranium-mining district. The geochemical parameters showed little variations over the 1.5 year study period. The highest metal concentrations found in creek sediments always coincided with the lowest metal concentrations in creek water at the slightly acidic site R3. Sequential extractions of R3 sediment revealed large portions of heavy metals (Ni, Cu, Zn, Pb, U bound to the iron oxide fraction. Light microscopy of glass slides exposed in creeks detected twisted stalks characteristic of microaerobic FeOB of the family Gallionellaceae at R3 but also at the acidic site R2. Sequences related to FeOB such as Gallionella ferruginea, Sideroxydans sp. CL21, Ferritrophicum radicicola, and Acidovorax sp. BrG1 were identified in the sediments. The highest fraction of clone sequences similar to the acidophilic ‘Ferrovum myxofaciens’ was detected in R1. Quantitative PCR using primer sets specific for Gallionella spp., Sideroxydans spp., and ‘Ferrovum myxofaciens’ revealed that approximately 72% (R2 sediment and 37% (R3 sediment of total bacterial 16S rRNA gene copies could be assigned to groups of FeOB with dominance of microaerobic Gallionella spp. at both sites. Gallionella spp. had similar and very high absolute and relative gene copy numbers in both sediment communities. Thus, Gallionella-like organisms appear to exhibit a greater acid and metal tolerance than shown before. Microaerobic FeOB from R3 creek sediment enriched in newly developed metal gradient tubes tolerated metal concentrations of 35 mM Co, 24 mM Ni, and 1.3 mM Cd, higher than those in sediments. Our results will extend the limited knowledge of FeOB at contaminated, moderately to slightly acidic environments.
Fabisch, Maria; Beulig, Felix; Akob, Denise M.; Küsel, Kirsten
2013-01-01
We identified and quantified abundant iron-oxidizing bacteria (FeOB) at three iron-rich, metal-contaminated creek sites with increasing sediment pH from extremely acidic (R1, pH 2.7), to moderately acidic (R2, pH 4.4), to slightly acidic (R3, pH 6.3) in a former uranium-mining district. The geochemical parameters showed little variations over the 1.5 year study period. The highest metal concentrations found in creek sediments always coincided with the lowest metal concentrations in creek water at the slightly acidic site R3. Sequential extractions of R3 sediment revealed large portions of heavy metals (Ni, Cu, Zn, Pb, U) bound to the iron oxide fraction. Light microscopy of glass slides exposed in creeks detected twisted stalks characteristic of microaerobic FeOB of the family Gallionellaceae at R3 but also at the acidic site R2. Sequences related to FeOB such as Gallionella ferruginea, Sideroxydans sp. CL21, Ferritrophicum radicicola, and Acidovorax sp. BrG1 were identified in the sediments. The highest fraction of clone sequences similar to the acidophilic “Ferrovum myxofaciens” was detected in R1. Quantitative PCR using primer sets specific for Gallionella spp., Sideroxydans spp., and “Ferrovum myxofaciens” revealed that ~72% (R2 sediment) and 37% (R3 sediment) of total bacterial 16S rRNA gene copies could be assigned to groups of FeOB with dominance of microaerobic Gallionella spp. at both sites. Gallionella spp. had similar and very high absolute and relative gene copy numbers in both sediment communities. Thus, Gallionella-like organisms appear to exhibit a greater acid and metal tolerance than shown before. Microaerobic FeOB from R3 creek sediment enriched in newly developed metal gradient tubes tolerated metal concentrations of 35 mM Co, 24 mM Ni, and 1.3 mM Cd, higher than those in sediments. Our results will extend the limited knowledge of FeOB at contaminated, moderately to slightly acidic environments.
International Nuclear Information System (INIS)
Suzuki, K.N.; Machado, E.C.; Machado, W.; Bellido, A.V.B.; Bellido, L.F.; Osso, J.A.; Lopes, R.T.
2014-01-01
The extent in which redox conditions can affect the removal kinetics of 58 Co and 65 Zn from tidal water by mangrove sediments was evaluated in microcosm experiments, simulating a tidal flooding period of 6 h. The average half-removal time (t 1/2 ) of 58 Co from overlaying water was slightly higher (7.3 h) under an N 2 -purged water column than under an aerated water column (5.4 h). A lower difference was found for 65 Zn (1.9 h vs. 1.5 h, respectively). Average removals of 58 Co activities from water were 54.6% (N 2 treatment) and 43.5% (aeration treatment), whereas these values were 88.0% and 92.7% for 65 Zn, respectively. Very contrasting sorption kinetics of different radiotracers occurred, while more oxidising conditions favoured only a slightly higher removal. Average 58 Co and 65 Zn inventories within sediments were 30.4% and 18.8% higher in the aeration treatment, respectively. A stronger particle-reactive behaviour was found for 65 Zn that was less redox-sensitive and more efficiently removed by sediments than 58 Co. - Highlights: ► Radiotracer experiments evidenced the role of mangrove sediments in trapping trace metals. ► Very contrasting removal kinetics from tidal water were observed for 65 Zn and 58 Co. ► Nearly 40%–50% of 58 Co activities and nearly 90% of 65 Zn activities in overlying water were removed. ► 65 Zn showed a stronger particle-reactive behaviour than observed for 58 Co. ► 58 Co was more sensitive to redox conditions in tidal water than observed for 65 Zn
Bert, Valérie; Seuntjens, Piet; Dejonghe, Winnie; Lacherez, Sophie; Thuy, Hoang Thi Thanh; Vandecasteele, Bart
2009-11-01
Polluted sediments in rivers may be transported by the river to the sea, spread over river banks and tidal marshes or managed, i.e. actively dredged and disposed of on land. Once sedimented on tidal marshes, alluvial areas or control flood areas, the polluted sediments enter semi-terrestrial ecosystems or agro-ecosystems and may pose a risk. Disposal of polluted dredged sediments on land may also lead to certain risks. Up to a few years ago, contaminated dredged sediments were placed in confined disposal facilities. The European policy encourages sediment valorisation and this will be a technological challenge for the near future. Currently, contaminated dredged sediments are often not valorisable due to their high content of contaminants and their consequent hazardous properties. In addition, it is generally admitted that treatment and re-use of heavily contaminated dredged sediments is not a cost-effective alternative to confined disposal. For contaminated sediments and associated disposal facilities used in the past, a realistic, low cost, safe, ecologically sound and sustainable management option is required. In this context, phytoremediation is proposed in the literature as a management option. The aim of this paper is to review the current knowledge on management, (phyto)remediation and associated risks in the particular case of sediments contaminated with organic and inorganic pollutants. This paper deals with the following features: (1) management and remediation of contaminated sediments and associated risk assessment; (2) management options for ecosystems on polluted sediments, based on phytoremediation of contaminated sediments with focus on phytoextraction, phytostabilisation and phytoremediation of organic pollutants and (3) microbial and mycorrhizal processes occurring in contaminated sediments during phytoremediation. In this review, an overview is given of phytoremediation as a management option for semi-terrestrial and terrestrial ecosystems
Goddard, K.E.
1989-01-01
The Whitewood Creek-Belle Fourche-Cheyenne River stream system in western South Dakota has been extensively contaminated by the discharge to Whitewood Creek of about 100 million tons of mill tailings from gold-mining operations. The resulting contaminated sediments contain unusually large concentrations of arsenic, as much as 11,000 micrograms/g, derived from the mineral arsenopyrite, as well as potentially toxic constituents derived from the ore-body minerals or from the milling processes. Because of the anomalous arsenic concentrations associated with the contamination, arsenic was used as an indicator for a geochemically based, random, sediment-sampling program. Arsenic concentrations in shallow, contaminated sediments along the flood plains of the streams were from 1 to 3 orders of magnitude larger than arsenic concentrations in uncontaminated sediments in about 75% of the flood plains of Whitewood Creek and the Belle Fourche River. Appreciable surface-water contamination resulting from the contaminated sediments is confined to Whitewood Creek and a reach of the Belle Fourche River downstream from the mouth of Whitewood Creek. In Whitewood Creek , dissolved-arsenic concentrations vary from about 20 to 80 microgram/L during the year in response to variations in groundwater inflow and dilution, whereas total-recoverable-arsenic concentrations vary from about 20 to 8 ,000 micrograms/L during short periods in response to rapid changes in suspended-sediment concentration. Contamination of the alluvial aquifer along the stream system is limited to areas in direct contact with large deposits of contaminated sediments. Within the aquifer, arsenic concentrations are thought to be controlled by sorption-desorption on metallic hydroxides. (USGS)
Sediment sources and transport in Kings Bay and vicinity, Georgia and Florida, July 8-16, 1982
Radtke, D.B.
1985-01-01
Water quality, bottom-material, suspended-sediment, and current velocity data were collected during July 1982 in Kings Bay and vicinity to provide information on the source and transport of estuarine sediments. Kings Bay and Cumberland Sound, the site of the Poseidon Submarine Base in southeast Georgia, are experiencing high rates of sediment deposition and accumulation, which are causing serious navigational and operational problems. Velocity, bathymetry, turbidity, and bottom-material data suggest sediment transported from lower Kings Bay is accumulating deposits of suspended sediment transported from Cumberland Sound on the floodtide and from upper Kings Bay and the tidal march drained by Marianna Creek on the ebbtide. Suspended-sediment discharges computed for consecutive 13-hr ebbtides and floodtides showed that a net quantity of suspended sediment was transported seaward from upper Kings Bay and Marianna Creek. A net landward transport of suspended sediment computed at the St. Marys Entrance indicated areas seaward of St. Marys Entrance may be supplying sediment to the shoaling areas of the estuary, including lower Kings Bay. (USGS)
Temmerman, S.; Bouma, T.J.; De Vries, M.B.; Wang, Z.B.; Govers, G.; Herman, P.M.J.
2005-01-01
A three-dimensional hydrodynamic and sediment transport model was used to study the relative impact of (1) vegetation, (2) micro-topography, and (3) water level fluctuations on the spatial flow and sedimentation patterns in a tidal marsh landscape during single inundation events. The model
Temmerman, S.; Bouma, T.J.; Govers, G.; Wang, Z.B.; de Vries, M.B.; Herman, P.M.J.
2005-01-01
A three-dimensional hydrodynamic and sediment transport model was used to study the relative impact of (1) vegetation, (2) micro-topography, and (3) water level fluctuations on the spatial flow and sedimentation patterns in a tidal marsh landscape during single inundation events. The model
McConnell, J.B.; Radtke, D.B.; Hale, T.W.; Buell, G.R.
1983-01-01
Water-quality, bottom-material, suspended-sediment, and current-velocity data were collected during November 1981 in Kings Bay and vicinity to provide information on the sources and transport of estuarine sediments. Kings Bay and Cumberland Sound , the site of the Poseidon Submarine Base in southeast Georgia, are experiencing high rates of sediment deposition and accumulation, which are causing serious navigational and operational problems. Velocity, bathymetry, turbidity, and bottom-material data suggest that the area in the vicinity of lower Kings Bay is accumulating deposits of suspended sediment transported from Cumberland Sound on the floodtide and from upper Kings Bay and the tidal marsh drained by Marianna Creek on the ebbtide. Suspended-sediment discharges computed for consecutive 13-hour ebbtides and floodtides showed that a net quantity of suspended sediment was transported seaward from upper Kings Bay and Marianna Creek. A net landward transport of suspended sediment computed at the St. Marys Entrance indicated areas seaward of St. Marys Entrance may be supplying sediment to the shoaling areas of the estuary, including lower Kings Bay. (USGS)
Sassi, M.; Duran-Matute, M.; van Kessel, Th.; Gerkema, Th.
2015-01-01
In multiple tidal-inlet systems such as the Dutch Wadden Sea, the exchange of sediments between the coastal lagoon and the adjacent sea is controlled by the combined effect of the tides, wind-driven flows, and density-driven flows. We investigate the variability of residual (tidally averaged) fluxes
Hughes, Z. J.; Georgiou, I. Y.; Gaweesh, A.; Hanegan, K.; FitzGerald, D.; Hein, C. J.
2017-12-01
Under accelerating sea-level rise (SLR), marshes are vulnerable to increased inundation, dependent on their ability to accrete vertically or expand into upland areas. Accretion is a function of organic and inorganic contributions from plant biomass and suspended sediment deposition, respectively. Along the east coast of the US, present rates of SLR are higher than they have been for over 1000 years and are expected to increase in the near future. To predict the resilience of saltmarshes, we urgently need improved understanding of spatial patterns of sediment transport and deposition within these systems. This study examines time-series of suspended sediment concentration and flow collected using ADCP-OBS units, deployed throughout the Great Marsh System. We compare the data to model results and observations of short and long term deposition throughout the system. Field observations show that tidal amplitude and phase vary throughout the Great Marsh. Tidal asymmetry increases inland from the estuary mouth, and the maximum phase lag is 2 hours. This effect is strongest during low slack tide; with a delay of only 30-45 minutes at high tide. Tidal velocities exhibit strong asymmetry, reflected in pulses of sediment movement. Sediment transport initiates at mid ebb, peaking 1.5-2.5 hours later, decreasing through low slack tide for 7-9 hours until high slack tide. The results have broad implications for the potential input of inorganic sediment to the marsh platform. Results from a validated Delft3D model reproduce field observations and expand spatial sediment transport trends. We experiment by releasing sediment in different parts of the estuary, mimicking marsh edge or tidal flat erosion, and tracking mud and sand transport trajectories. Sands remains proximal to the erosion site, whereas mud is more mobile and travels farther, reaching the inlet within days of erosion. Longer simulations suggest that despite higher mobility, muds remain mostly in the channels and
Facies architecture of heterolithic tidal deposits : The Holocene Holland Tidal Basin
Donselaar, M.E.; Geel, C.R.
2007-01-01
The size, shape and spatial position of lithofacies types (or facies architecture) in a tidal estuarine basin are complex and therefore difficult to model. The tidal currents in the basin concentrate sand-sized sediment in a branching pattern of tidal channels and fringing tidal flats. Away from the
Morphodynamics of the Manyema Tidal Delta at Kunduchi, Tanzania
African Journals Online (AJOL)
Keywords: Morphodynamics, Kunduchi, Manyema, shoreline change, tidal creek, tidal delta. Abstract—The prevailing northward longshore drift of beach sand on the northern part of Msasani Bay, north of Dar es Salaam, is interrupted at Kunduchi by the tidal flushing of ... Western Indian Ocean J. Mar. Sci. Vol. 11, No. 2, pp.
Heterogeneous distribution of prokaryotes and viruses at the microscale in a tidal sediment
DEFF Research Database (Denmark)
Carreira, Cátia; Larsen, Morten; Glud, Ronnie
2013-01-01
In this study we show for the first time the microscale (mm) 2- and 3-dimensional spatial distribution and abundance of prokaryotes, viruses, and oxygen in a tidal sediment. Prokaryotes and viruses were highly heterogeneously distributed with patches of elevated abundances surrounded by areas of ...
Digital Repository Service at National Institute of Oceanography (India)
Volvoikar, S.P.; Nayak, G.N.
Metal speciation studies were carried out on three intertidal core sediments of the industrially impacted Dudh creek located along west coast of India Metals indicated a drastic increase in the bioavailable fraction towards the surface of the cores...
Sloto, Ronald A.; Olson, Leif E.
2011-01-01
Turbidity and suspended-sediment concentration data were collected by the U.S. Geological Survey (USGS) at four stream stations--French Creek near Phoenixville, West Branch Brandywine Creek near Honey Brook, West Branch Brandywine Creek at Modena, and East Branch Brandywine Creek below Downingtown--in Chester County, Pa. Sedimentation and siltation is the leading cause of stream impairment in Chester County, and these data are critical for quantifying sediment transport. This study was conducted by the USGS in cooperation with the Chester County Water Resources Authority and the Chester County Health Department. Data from optical turbidity sensors deployed at the four stations were recorded at 15- or 30-minute intervals by a data logger and uploaded every 1 to 4 hours to the USGS database. Most of the suspended-sediment samples were collected using automated samplers. The use of optical sensors to continuously monitor turbidity provided an accurate estimate of sediment fluctuations without the collection and analysis costs associated with intensive sampling during storms. Turbidity was used as a surrogate for suspended-sediment concentration (SSC), which is a measure of sedimentation and siltation. Regression models were developed between SSC and turbidity for each of the monitoring stations using SSC data collected from the automated samplers and turbidity data collected at each station. Instantaneous suspended-sediment loads (SSL) were computed from time-series turbidity and discharge data for the 2008 and 2009 water years using the regression equations. The instantaneous computations of SSL were summed to provide daily, storm, and water year annual loads. The annual SSL contributed from each basin was divided by the upstream drainage area to estimate the annual sediment yield. For all four basins, storms provided more than 96 percent of the annual SSL. In each basin, four storms generally provided over half the annual SSL each water year. Stormflows with the
Keith, Mackenzie K.; Sobieszczyk, Steven; Goldman, Jami H.; Rounds, Stewart A.
2014-01-01
Organic matter (OM) is abundant in Fanno Creek, Oregon, USA, and has been tied to a variety of water-quality concerns, including periods of low dissolved oxygen downstream in the Tualatin River, Oregon. The key sources of OM in Fanno Creek and other Tualatin River tributaries have not been fully identified, although isotopic analyses from previous studies indicated a predominantly terrestrial source. This study investigates the role of fine sediment erosion and deposition (mechanisms and spatial patterns) in relation to OM transport. Geomorphic mapping within the Fanno Creek floodplain shows that a large portion (approximately 70%) of the banks are eroding or subject to erosion, likely as a result of the imbalance caused by anthropogenic alteration. Field measurements of long- and short-term bank erosion average 4.2 cm/year and average measurements of deposition for the watershed are 4.8 cm/year. The balance between average annual erosion and deposition indicates an export of 3,250 metric tons (tonnes, t) of fine sediment to the Tualatin River—about twice the average annual export of 1,880 t of sediment at a location 2.4 km from the creek’s mouth calculated from suspended sediment load regressions from continuous turbidity data and suspended sediment samples. Carbon content from field samples of bank material, combined with fine sediment export rates, indicates that about 29–67 t of carbon, or about 49–116 t of OM, from bank sediment may be exported to the Tualatin River from Fanno Creek annually, an estimate that is a lower bound because it does not account for the mass wasting of organic-rich O and A soil horizons that enter the stream.
Hartzell, Sharon E; Unger, Michael A; McGee, Beth L; Wilson, Sacoby M; Yonkos, Lance T
2017-10-01
Estuarine sediments in regions with prolonged histories of industrial activity are often laden to significant depths with complex contaminant mixtures, including trace metals and persistent organic pollutants. Given the complexity of assessing risks from multi-contaminant exposures, the direct measurement of impacts to biological receptors is central to characterizing contaminated sediment sites. Though biological consequences are less commonly assessed at depth, laboratory-based toxicity testing of subsurface sediments can be used to delineate the scope of contamination at impacted sites. The extent and depth of sediment toxicity in Bear Creek, near Baltimore, Maryland, USA, was delineated using 10-day acute toxicity tests with the estuarine amphipod Leptocheirus plumulosus, and chemical analysis of trace metals and persistent organic pollutants. A gradient of toxicity was demonstrated in surface sediments with 21 of 22 tested sites differing significantly from controls. Effects were most pronounced (100% lethality) at sites proximate to a historic industrial complex. Sediments from eight of nine core samples to depths of 80 cm were particularly impacted (i.e., caused significant lethality to L. plumulosus) even in locations overlain with relatively non-toxic surface sediments, supporting a conclusion that toxicity observed at the surface (top 2 cm) does not adequately predict toxicity at depth. In seven of nine sites, toxicity of surface sediments differed from toxicity at levels beneath by 28 to 69%, in five instances underestimating toxicity (28 to 69%), and in two instances overestimating toxicity (44 to 56%). Multiple contaminants exceeded sediment quality guidelines and correlated positively with toxic responses within surface sediments (e.g., chromium, nickel, polycyclic aromatic hydrocarbon (PAH), total petroleum hydrocarbon). Use of an antibody-based PAH biosensor revealed that porewater PAH concentrations also increased with depth at most sites. This
Sawyer, A. H.; Barnes, R.; Wallace, C.; Knights, D.; Tight, D.; Bayer, M.
2017-12-01
Tides in coastal rivers can propagate tens to hundreds of kilometers inland and drive large daily changes in water and nitrogen exchange across the sediment-water interface. We use field observations and numerical models to illuminate hydrodynamic controls on nitrogen export from the riparian aquifer to a fresh, tidal reach of White Clay Creek (Delaware, USA). In the banks, an aerobic zone with high groundwater nitrate concentrations occurs near the fluctuating water table. Continuous depth-resolved measurements of redox potential suggest that this zone is relatively stable over tidal timescales but moves up or down in response to storms. The main source of dissolved oxygen is soil air that is imbibed in the zone of water table fluctuations, and the source of nitrate is likely nitrification of ammonium produced locally from the mineralization of organic matter in floodplain soils. Much of the nitrate is removed by denitrification along oscillating flow paths towards the channel. Within centimeters of the sediment-water interface, denitrification is limited by the mixing of groundwater with oxygen-rich river water. Our models predict that the benthic zones of tidal rivers play an important role in removing new nitrate inputs from discharging groundwater but may be less effective at removing nitrate from river water. Nitrate removal and production rates are expected to vary significantly along tidal rivers as permeability, organic matter content, tidal range vary. It is imperative that we understand nitrogen dynamics along tidal rivers and their role in nitrogen export to the coast.
Koetje, K. M.; Foster, D. L.; Lippmann, T. C.
2017-12-01
Observations of the vertical structure of tidal flows obtained in 2016 and 2017 in the Great Bay Estuary, NH show evidence of transitional tidal boundary layers at deployment locations on shallow mudflats. High-resolution bottom boundary layer currents, hydrography, turbidity, and bed characteristics were observed with an acoustic Doppler current profiler (ADCP), an acoustic Doppler velocimeter (ADV), conductivity-depth-temperature (CTD) sensors, optical backscatter sensors, multibeam bathymetric surveys, and sediment grab samples and cores. Over the 2.5 m tidal range and at water depths ranging from 0.3 m to 1.5 m at mean lower low water, peak flows ranged from 10 cm/s to 30 cm/s and were primarily driven by the tides. A downward-looking ADCP captured the velocity profile over the lowest 1 m of the water column. Results consistently show a dual-log layer system, with evidence of a lower layer within 15 cm of the bed, another layer above approximately 30 cm from the bed, and a transitional region where the flow field rotates between that the two layers that can be as much as 180 degrees out of phase. CTD casts collected over a complete tidal cycle suggest that the weak thermohaline stratification is not responsible for development of the two layers. On the other hand, acoustic and optical backscatter measurements show spatial and temporal variability in suspended sediments that are dependant on tidal phase. Current work includes an examination of the relationship between sediment concentrations in the water column and velocity profile characteristics, along with an effort to quantify the impact of rotation and dual-log layers on bed stress.
Simulation of contaminated sediment transport in White Oak Creek basin
International Nuclear Information System (INIS)
Bao, Y.; Clapp, R.B.; Brenkert, A.L.; Moore, T.D.; Fontaine, T.A.
1995-01-01
This paper presents a systematic approach to management of the contaminated sediments in the White Oak Creek watershed at Oak Ridge National Laboratory near Oak Ridge, Tennessee. The primary contaminant of concern is radioactive cesium-137 ( 137 Cs), which binds to soil and sediment particles. The key components in the approach include an intensive sampling and monitoring system for flood events; modeling of hydrological processes, sediment transport, and contaminant flux movement; and a decision framework with a detailed human health risk analysis. Emphasis is placed on modeling of watershed rainfall-runoff and contaminated sediment transport during flooding periods using the Hydrologic Simulation Program- Fortran (HSPF) model. Because a large number of parameters are required in HSPF modeling, the major effort in the modeling process is the calibration of model parameters to make simulation results and measured values agree as closely as possible. An optimization model incorporating the concepts of an expert system was developed to improve calibration results and efficiency. Over a five-year simulation period, the simulated flows match the observed values well. Simulated total amount of sediment loads at various locations during storms match with the observed values within a factor of 1.5. Simulated annual releases of 137 Cs off-site locations match the data within a factor of 2 for the five-year period. The comprehensive modeling approach can provide a valuable tool for decision makers to quantitatively analyze sediment erosion, deposition, and transport; exposure risk related to radionuclides in contaminated sediment; and various management strategies
Digital Repository Service at National Institute of Oceanography (India)
Ingole, S.A.; Dhaktode, S.S.; Kadam, A.N.
The surface sediment samples were collected by van Veen grab sampler during premonsoon, monsoon and postmonsoon seasons from Bombay harbour, Dharamtar creek and Amba river estuary Moisture content of the samples ranges from 36 to 67.5...
Study on accumulation of heavy metals in Mangrove sediments, Gabrik Creek (Jask)
International Nuclear Information System (INIS)
Zarezadeh, R.; Rezaee, P.
2016-01-01
Gabrik in the East of Hormozgan province is Mangrove habitat and one of the important Mangrove protected area. This area is located in Oman coasts. This zone because of building Jagin dam on Gabrick River and existence of sand barrier and exposure of pollution, it is possible to destroy or to be important threats of this planet. Base on importance of this sea inhabitation some of sedimentology parameters and geochemical Mangrove's sediments have been analyzed. In this study for sieve used Hydrometric method and for Identification of organic matter used electronic furnace heat 500 degree centigrade for 6 hours. Quantity of calcium carbonate analyzed by titration and for condenses of heavy metal Zn, Pb and Ni chemical decomposition atomic absorption by Thermo-solaar (±1µg/g). Results showed that mean content of carbonate and organic matter in the sediments is 27 percent and 3.36 percent respectively. Contamination heavy metals Pb, Zn and Ni in the sediments of this mangrove, were studied throughout Gabrik creek. Metal concentration analyses were performed using atomic absorption spectrometry (AAS). Mean concentration of the heavy metals Pb, Zn and Ni in sediments was measured 67.63, 69.63 and 76.53 µg/g dry weights respectively. According to determine geoaccumulation index (Igeo), contamination factor (CF), the degree of contamination correction (mCd) and compared the heavy metal concentrations with to the mean concentrations of heavy metals in sedimentary rock (shales) and China and American standards. The results in this study showed that there is no pollution from Zn metal but there are pollutions from Ni and Pb metals and concentration this heavy metals aren't critical. The origin of these heavy metals can be a result of maintenance of fishing vessels in Gabrik Creek, activities or fuel smuggling and perhaps oil compounds spill into the water and human refuse in the region.
Majcher, Emily H.; Phelan, Daniel J.; Lorah, Michelle M.; McGinty, Angela L.
2007-01-01
Wetlands act as natural transition zones between ground water and surface water, characterized by the complex interdependency of hydrology, chemical and physical properties, and biotic effects. Although field and laboratory demonstrations have shown efficient natural attenuation processes in the non-seep wetland areas and stream bottom sediments of West Branch Canal Creek, chlorinated volatile organic compounds are present in a freshwater tidal creek at Aberdeen Proving Ground, Maryland. Volatile organic compound concentrations in surface water indicate that in some areas of the wetland, preferential flow paths or seeps allow transport of organic compounds from the contaminated sand aquifer to the overlying surface water without undergoing natural attenuation. From 2002 through 2004, the U.S. Geological Survey, in cooperation with the Environmental Conservation and Restoration Division of the U.S. Army Garrison, Aberdeen Proving Ground, characterized preferential ground-water seepage as part of an ongoing investigation of contaminant distribution and natural attenuation processes in wetlands at this site. Seep areas were discrete and spatially consistent during thermal infrared surveys in 2002, 2003, and 2004 throughout West Branch Canal Creek wetlands. In these seep areas, temperature measurements in shallow pore water and sediment more closely resembled those in ground water than those in nearby surface water. Generally, pore water in seep areas contaminated with chlorinated volatile organic compounds had lower methane and greater volatile organic compound concentrations than pore water in non-seep wetland sediments. The volatile organic compounds detected in shallow pore water in seeps were spatially similar to the dominant volatile organic compounds in the underlying Canal Creek aquifer, with both parent and anaerobic daughter compounds detected. Seep locations characterized as focused seeps contained the highest concentrations of chlorinated parent compounds
Box, Stephen E.; Wallis, John C.; Briggs, Paul H.; Brown, Zoe Ann
2005-01-01
This report presents the results of one aspect of an integrated watershed-characterization study that was undertaken to assess the impacts of historical mining and milling of silver-lead-zinc ores on water and sediment composition and on aquatic biota in streams draining the northern part of the Coeur d?Alene Mining District in northern Idaho. We present the results of chemical analyses of 62 samples of streambed sediment, 19 samples of suspended sediment, 23 samples of streambank soil, and 29 samples of mine- and mill-related artificial- fill material collected from the drainages of Prichard, Eagle, and Beaver Creeks, all tributaries to the North Fork of the Coeur d?Alene River. All samples were sieved into three grain-size fractions (Beaver Creek drainages has resulted in enrichments of lead, zinc, mercury, arsenic, cadmium, silver, copper, cobalt, and, to a lesser extent, iron and manganese in streambed sediment. Using samples collected from the relatively unimpacted West Fork of Eagle Creek as representative of background compositions, streambed sediment in the vicinity of the mines and millsites has Pb and Zn contents of 20 to 100 times background values, decreasing to 2 to 5 times background values at the mouth of the each stream, 15 to 20 km downstream. Lesser enrichments (<10 times background values) of mercury and arsenic also are generally associated with, and decrease downstream from, historical silver-lead-zinc mining in the drainages. However, enrichments of arsenic and, to a lesser extent, mercury also are areally associated with the lode gold deposits along Prichard Creek near Murray, which were not studied here. Metal contents in samples of unfractionated suspended sediment collected during a high-flow event in April 2000 are generally similar to, but slightly higher than, those in the fine (<0.063- mm grain size) fraction of streambed sediment from the same sampling site. Although metal enrichment in streambed sediment typically begins adjacent to
Kennedy, Ben W.; Langley, Dustin E.
2007-01-01
Executive Summary The U.S. Geological Survey, in cooperation with the Bureau of Land Management, completed an assessment of hydrology, water quality, and trace-element concentrations in streambed sediment of the upper Birch Creek watershed near Central, Alaska. The assessment covered one site on upper Birch Creek and paired sites, upstream and downstream from mined areas, on Frying Pan Creek and Harrison Creek. Stream-discharge and suspended-sediment concentration data collected at other selected mined and unmined sites helped characterize conditions in the upper Birch Creek watershed. The purpose of the project was to provide the Bureau of Land Management with baseline information to evaluate watershed water quality and plan reclamation efforts. Data collection began in September 2001 and ended in September 2005. There were substantial geomorphic disturbances in the stream channel and flood plain along several miles of Harrison Creek. Placer mining has physically altered the natural stream channel morphology and removed streamside vegetation. There has been little or no effort to re-contour waste rock piles. During high-flow events, the abandoned placer-mine areas on Harrison Creek will likely contribute large quantities of sediment downstream unless the mined areas are reclaimed. During 2004 and 2005, no substantial changes in nutrient or major-ion concentrations were detected in water samples collected upstream from mined areas compared with water samples collected downstream from mined areas on Frying Pan Creek and Harrison Creek that could not be attributed to natural variation. This also was true for dissolved oxygen, pH, and specific conductance-a measure of total dissolved solids. Sample sites downstream from mined areas on Harrison Creek and Frying Pan Creek had higher median suspended-sediment concentrations, by a few milligrams per liter, than respective upstream sites. However, it is difficult to attach much importance to the small downstream increase
Wilson, C.; Goodbred, S. L., Jr.; Wallace Auerbach, L.; Ahmed, K. R.; Small, C.; Sams, S. E.
2014-12-01
Over the last century, land use changes in the Ganges-Brahmaputra tidal delta have transformed >5000 km2 of intertidal mangrove forest to densely inhabited, agricultural islands that have been embanked to protect against tides and storm surges (i.e., polders). More recently, the conversion of rice paddies to profitable shrimp aquaculture has become increasingly widespread. Recent field studies documented that poldering in southwest Bangladesh has resulted in an elevation deficit relative to that of the natural mangrove forests and mean high water (MHW). The offset is a function of lost sedimentation, enhanced compaction, and an effective rise in MHW from tidal amplification. The morphologic adjustment of the tidal channel network to these perturbations, however, has gone largely undocumented. One effect has been the shoaling of many channels due to decreases in fluvial discharge and tidal prism. We document a previously unrecognized anthropogenic component: the widespread closure of large conduit tidal channels for land reclamation and shrimp farming. GIS analysis of historical Landsat and Google Earth imagery within six 1000 km2 study areas reveals that the tidal network in the natural Sundarbans mangrove forest has remained relatively constant since the 1970s, while significant changes are observed in human-modified areas. Construction of the original embankments removed >1000 km of primary tidal creeks, and >80 km2 of land has been reclaimed outside of polders through the closure of formerly active tidal channels (decrease in mean channel width from 256±91 m to 25±10 m). Tidal restriction by large sluice gates is prevalent, favoring local channel siltation. Furthermore, severing the intertidal platform and large conduit channels from the tidal network has had serious repercussions, such as increased lateral migration and straightening of the remaining channels. Where banklines have eroded, the adjacent embankments appear to be more vulnerable to failure, as
Poppe, K.; Rybczyk, J.; Parr, L.; Merrill, A.
2017-12-01
Tidal marshes are typically productive and depositional environments potentially conducive to high rates of carbon sequestration. Though they have been recognized globally for their ability to store "blue carbon", there is a paucity of comprehensive site-scale data from the Pacific Northwest U.S. Here we report carbon stocks and sequestration rates for an existing and a recently restored brackish marsh in the Stillaguamish River Estuary, in Puget Sound, Washington. The Stillaguamish River discharges into the Port Susan Bay Preserve which contains a 150-acre tidal marsh restoration site that was reintroduced to the tidal regime in 2012 from its previous use as diked and drained farmland. We hypothesized that the restoration would not only maximize carbon storage in former tidal wetlands but also, through the accumulation of organic and mineral matter, enhance these systems' resilience to rising sea levels. We collected sediment cores from 13 sites across the estuary, within and outside of the restoration area, to determine bulk density, organic and carbon content with depth, long-term accretion rates, and belowground biomass. We also measured aboveground net primary productivity. Carbon stocks at each site were partitioned into three components as recommended by the IPCC: aboveground biomass, belowground biomass, and sediment carbon. We additionally measured elevation change with surface elevation tables (SETs). Mean sediment carbon stocks in the upper 30 cm of sediment within the restoration area (6.45 kg C/m2) were similar to those measured in the adjacent natural marsh (6.82 kg C/m2). However, mean elevation change, as measured by SETs, were substantially higher in the restoration area (3.10 cm/yr) than in the natural marsh sites (0.79 cm/yr). As a result, carbon accumulation rates were also higher in the restoration area (821 g C/m2/yr) compared to the natural marsh sites (195 g C/m2/yr).
Miller, Lisa D.; Stogner, Sr., Robert W.
2017-09-01
From 2007 through 2015, the U.S. Geological Survey, in cooperation with Colorado Springs City Engineering, conducted a study in the Fountain and Monument Creek watersheds, Colorado, to characterize surface-water quality and suspended-sediment conditions for three different streamflow regimes with an emphasis on characterizing water quality during storm runoff. Data collected during this study were used to evaluate the effects of stormflows and wastewater-treatment effluent discharge on Fountain and Monument Creeks in the Colorado Springs, Colorado, area. Water-quality samples were collected at 2 sites on Upper Fountain Creek, 2 sites on Monument Creek, 3 sites on Lower Fountain Creek, and 13 tributary sites during 3 flow regimes: cold-season flow (November–April), warm-season flow (May–October), and stormflow from 2007 through 2015. During 2015, additional samples were collected and analyzed for Escherichia coli (E. coli) during dry weather conditions at 41 sites, located in E. coli impaired stream reaches, to help identify source areas and scope of the impairment.Concentrations of E. coli, total arsenic, and dissolved copper, selenium, and zinc in surface-water samples were compared to Colorado in-stream standards. Stormflow concentrations of E. coli frequently exceeded the recreational use standard of 126 colonies per 100 milliliters at main-stem and tributary sites by more than an order of magnitude. Even though median E. coli concentrations in warm-season flow samples were lower than median concentrations in storm-flow samples, the water quality standard for E. coli was still exceeded at most main-stem sites and many tributary sites during warm-season flows. Six samples (three warm-season flow and three stormflow samples) collected from Upper Fountain Creek, upstream from the confluence of Monument Creek, and two stormflow samples collected from Lower Fountain Creek, downstream from the confluence with Monument Creek, exceeded the acute water
Saltmarsh creek bank stability: Biostabilisation and consolidation with depth
Chen, Y.; Thompson, C. E. L.; Collins, M. B.
2012-03-01
The stability of cohesive sediments of a saltmarsh in Southern England was measured in the field and the laboratory using a Cohesive Strength Meter (CSM) and a shear vane apparatus. Cores and sediment samples were collected from two tidal creek banks, covered by Atriplex portulacoides (Sea Purslane) and Juncus maritimus (Sea Rush), respectively. The objectives of the study were to examine the variation of sediment stability throughout banks with cantilevers present and investigate the influence of roots and downcore consolidation on bank stability. Data on erosion threshold and shear strength were interpreted with reference to bank depth, sediment properties and biological influences. The higher average erosion threshold was from the Sea Purslane bank whilst the Sea Rush bank showed higher average vane shear strength. The vertical variation in core sediment stability was mainly affected by roots and downcore consolidation with depth. The data obtained from the bank faces revealed that vertical variations in both erosion threshold and vane shear strength were affected primarily by roots and algae. A quantitative estimate of the relative contributions of roots and downcore consolidation to bank sediment stability was undertaken using the bank stability data and sediment density data. This showed that roots contributed more to the Sea Purslane bank stability than downcore consolidation, whilst downcore consolidation has more pronounced effects on the Sea Rush bank stability.
CREEK Project's Oyster Biomass Database for Eight Creeks in the North Inlet Estuary, South Carolina
Baruch Institute for Marine and Coastal Sciences, Univ of South Carolina — A group of eight tidal creeks dominated by oysters, Crassostrea virginica, in North Inlet Estuary, South Carolina, USA were studied using a replicated BACI (Before -...
Sloto, Ronald A.; Gellis, Allen C.; Galeone, Daniel G.
2012-01-01
Laurel Hill Creek is a watershed of 125 square miles located mostly in Somerset County, Pennsylvania, with small areas extending into Fayette and Westmoreland Counties. The upper part of the watershed is on the Pennsylvania Department of Environmental Protection 303(d) list of impaired streams because of siltation, nutrients, and low dissolved oxygen concentrations. The objectives of this study were to (1) estimate the annual sediment load, (2) estimate the annual nitrogen load, and (3) identify the major sources of fine-grained sediment using the sediment-fingerprinting approach. This study by the U.S. Geological Survey (USGS) was done in cooperation with the Somerset County Conservation District. Discharge, suspended-sediment, and nutrient data were collected at two streamflow-gaging stations—Laurel Hill Creek near Bakersville, Pa., (station 03079600) and Laurel Hill Creek at Ursina, Pa., (station 03080000)—and one ungaged stream site, Laurel Hill Creek below Laurel Hill Creek Lake at Trent (station 03079655). Concentrations of nutrients generally were low. Concentrations of ammonia were less than 0.2 milligrams per liter (mg/L), and concentrations of phosphorus were less than 0.3 mg/L. Most concentrations of phosphorus were less than the detection limit of 0.02 mg/L. Most water samples had concentrations of nitrate plus nitrite less than 1.0 mg/L. At the Bakersville station, concentrations of total nitrogen ranged from 0.63 to 1.3 mg/L in base-flow samples and from 0.57 to 1.5 mg/L in storm composite samples. Median concentrations were 0.88 mg/L in base-flow samples and 1.2 mg/L in storm composite samples. At the Ursina station, concentrations of total nitrogen ranged from 0.25 to 0.92 mg/L in base-flow samples; the median concentration was 0.57 mg/L. The estimated total nitrogen load at the Bakersville station was 262 pounds (lb) for 11 months of the 2010 water year (November 2009 to September 2010) and 266 lb for the 2011 water year. Most of the total
Juracek, Kyle E.
2011-01-01
Continuous streamflow and turbidity data collected from October 1, 2008, to September 30, 2010, at streamgage sites upstream and downstream from Kanopolis and Tuttle Creek Lakes, Kansas, were used to compute the total suspended-sediment load delivered to and released from each reservoir as well as the sediment trap efficiency for each reservoir. Ongoing sedimentation is decreasing the ability of the reservoirs to serve several purposes including flood control, water supply, and recreation. River channel stability upstream and downstream from the reservoirs was assessed using historical streamgage information. For Kanopolis Lake, the total 2-year inflow suspended-sediment load was computed to be 600 million pounds. Most of the suspended-sediment load was delivered during short-term, high-discharge periods. The total 2-year outflow suspended-sediment load was computed to be 31 million pounds. Sediment trap efficiency for the reservoir was estimated to be 95 percent. The mean annual suspended-sediment yield from the upstream basin was estimated to be 129,000 pounds per square mile per year. No pronounced changes in channel width were evident at five streamgage sites located upstream from the reservoir. At the Ellsworth streamgage site, located upstream from the reservoir, long-term channel-bed aggradation was followed by a period of stability. Current (2010) conditions at five streamgages located upstream from the reservoir were typified by channel-bed stability. At the Langley streamgage site, located immediately downstream from the reservoir, the channel bed degraded 6.15 feet from 1948 to 2010. For Tuttle Creek Lake, the total 2-year inflow suspended-sediment load was computed to be 13.3 billion pounds. Most of the suspended-sediment load was delivered during short-term, high-discharge periods. The total 2-year outflow suspended-sediment load was computed to be 327 million pounds. Sediment trap efficiency for the reservoir was estimated to be 98 percent. The mean
Slowey, Aaron J.; Rytuba, James J.; Hothem, Roger L.; May, Jason T.
2007-01-01
Executive Summary The Oat Hill Extension (OHE) Mine is one of several mercury mines located in the James Creek/Pope Creek watershed that produced mercury from the 1870's until 1944 (U.S. Bureau of Mines, 1965). The OHE Mine developed veins and mineralized fault zones hosted in sandstone that extended eastward from the Oat Hill Mine. Waste material from the Oat Hill Mine was reprocessed at the OHE Mine using gravity separation methods to obtain cinnabar concentrates that were processed in a retort. The U.S. Bureau of Land Management requested that the U.S. Geological Survey measure and characterize mercury and other chemical constituents that are potentially relevant to ecological impairment of biota in tailings, sediment, and water at the OHE Mine and in the tributaries of James Creek that drain the mine area (termed Drainage A and B) (Figs. 1 and 2). This report summarizes such data obtained from sampling of tailings and sediments at the OHE on October 17, 2003; water, sediment, and biota from James Creek on May 20, 2004; and biota on October 29, 2004. These data are interpreted to provide a preliminary assessment of the potential ecological impact of the mine on the James Creek watershed. The mine tailings are unusual in that they have not been roasted and contain relatively high concentrations of mercury (400 to 1200 ppm) compared to unroasted waste rock at other mines. These tailings have contaminated a tributary to James Creek with mercury primarily by erosion, on the basis of higher concentration of mercury (780 ng/L) measured in unfiltered (total mercury, HgT) spring water flowing from the OHE to James Creek compared to 5 to 14 ng/L HgT measured in James Creek itself. Tailing piles (presumably from past Oat Hill mine dumping) near the USBLM property boundary and upstream of the main OHE mine drainage channel (Drainage A; Fig. 2) also likely emit mercury, on the basis of their mercury composition (930 to 1200 ppm). The OHE spring water is likely an
Jack Lewis
1998-01-01
Suspended sediment has been sampled at both the North and South Fork weirs of Caspar Creek in northwestern California since 1963, and at 13 tributary locations in the North Fork since 1986. The North Fork gaging station (NFC) was used as a control to evaluate the effects of logging in the South Fork, in the 1970's, on annual sediment loads. In the most...
Summary of oceanographic and water-quality measurements in Barnegat Bay, New Jersey, 2014–15
Suttles, Steven E.; Ganju, Neil K.; Montgomery, Ellyn T.; Dickhudt, Patrick J.; Borden, Jonathan; Brosnahan, Sandra M.; Martini, Marinna A.
2016-09-26
Scientists and technical support staff from the U.S. Geological Survey measured suspended-sediment concentrations, currents, pressure, and water temperature in two tidal creeks, Reedy Creek and Dinner Creek, in Barnegat Bay, New Jersey, from August 11, 2014, to July 10, 2015 as part of the Estuarine Physical Response to Storms project (GS2–2D). The oceanographic and water-quality data quantify suspended-sediment transport in Reedy Creek and Dinner Creek, which are part of a tidal marsh wetland complex in the Edwin B. Forsythe National Wildlife Refuge. All deployed instruments were removed between January 7, 2015, and April 14, 2015, to avoid damage by ice.
Balanced Sediment Fluxes in Southern California's Mediterranean-climate Zone Salt Marshes
Rosencranz, J. A.; Dickhudt, P.; Ganju, N. K.; Thorne, K.; Takekawa, J.; Ambrose, R. F.; Guntenspergen, G. R.; Brosnahan, S.; MacDonald, G. M.
2015-12-01
Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many southern California, USA salt marshes import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are also potentially important for marsh stability. We calculated tidal creek sediment fluxes within a sediment starved 1.5 km2 salt marsh (Seal Beach) and a less modified 1 km2 marsh (Mugu) with a watershed sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12000 and 8800 kg in a western channel. This offset 8700 kg export during two months of dry weather, while landward net fluxes in the eastern channel accounted for 33% of the import. During the storm, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1-2 mm near creek levees. An exceptionally high tide sequence at Mugu yielded 4.4 g/s mean sediment flux, importing 1700 kg, accounting for 20% of dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are currently geomorphically stable. Our results suggest that storms and exceptionally high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea-level rise scenarios, results suggest that balanced sediment fluxes may lead to marsh elevational instability, based on estimated mineral sediment deficits.
Majcher, Emily H.; Lorah, Michelle M.; Phelan, Daniel J.; McGinty, Angela L.
2009-01-01
Because of a lack of available in situ remediation methods for sensitive wetland environments where contaminated groundwater discharges, the U.S. Geological Survey, in cooperation with the U.S. Army Garrison, Aberdeen Proving Ground, Maryland, conceived, designed, and pilot tested a permeable reactive mat that can be placed horizontally at the groundwater/surface-water interface. Development of the reactive mat was part of an enhanced bioremediation study in a tidal wetland area along West Branch Canal Creek at Aberdeen Proving Ground, where localized areas of preferential discharge (seeps) transport groundwater contaminated with carbon tetrachloride, chloroform, tetrachloroethene, trichloroethene, and 1,1,2,2-tetrachloroethane from the Canal Creek aquifer to land surface. The reactive mat consisted of a mixture of commercially available organic- and nutrient-rich peat and compost that was bioaugmented with a dechlorinating microbial consortium, WBC-2, developed for this study. Due to elevated chlorinated methane concentrations in the pilot test site, a layer of zero-valent iron mixed with the peat and compost was added at the base of the reactive mat to promote simultaneous abiotic and biotic degradation. The reactive mat for the pilot test area was designed to optimize chlorinated volatile organic compound degradation efficiency without altering the geotechnical and hydraulic characteristics, or creating undesirable water quality in the surrounding wetland area, which is referred to in this report as achieving geotechnical, hydraulic, and water-quality compatibility. Optimization of degradation efficiency was achieved through the selection of a sustainable organic reactive matrix, electron donor, and bioaugmentation method. Consideration of geotechnical compatibility through design calculations of bearing capacity, settlement, and geotextile selection showed that a 2- to 3-feet tolerable thickness of the mat was possible, with 0.17 feet settlement predicted for
International Nuclear Information System (INIS)
Liaghati, Tania; Cox, Malcolm E.; Preda, Micaela
2005-01-01
Dissolved and extractable iron concentrations in surface water, groundwater and bottom sediments were determined for Halls Creek, a small subtropical tidally influenced creek. Dissolved iron concentrations were much higher in fresh surface waters and groundwater compared to the estuarine water. In bottom sediments, iron minerals were determined by X-ray diffraction (XRD); of these, hematite (up to 11%) has formed by precipitation from iron-rich water in the freshwater section of the catchment. Pyrite was only identified in the estuarine reach and demonstrated several morphologies [identified by scanning electron microscopy (SEM)] including loosely and closely packed framboids, and the euhedral form. The forms of pyrite found in bottom sediments indicate in situ production and recrystallisation. In surface waters, pyrite was detected in suspended sediment; due to oxygen concentrations well above 50 μmol/l, it was concluded that framboids do not form in the water column, but are within resuspended bottom sediments or eroded from creek banks. The persistence of framboids in suspended sediments, where oxygen levels are relatively high, could be due to their silica and clay-rich coatings, which prevent a rapid oxidation of the pyrite. In addition to identifying processes of formation and transport of pyrite, this study has environmental significance, as this mineral is a potential source of bioavailable forms of iron, which can be a major nutrient supporting algal growth
Morphodynamics of the Manyema tidal delta 1 LIST OF TABLES ...
African Journals Online (AJOL)
Kheira Kortenbout
Morphodynamics of the Manyema tidal delta. 1. LIST OF ... Location of Manyema Creek and its associated tidal delta platform at Kunduchi. Fig. 2. ... platform. Beachcomber. Hotel. Whitesands. Hotel. Kunduchi. Beach Hotel. Giraffe. Hotel. INDIAN. OCEAN. Mombasa. Dar es. Salaam. KUNDUCHI. KENYA. TANZANIA.
A study of the fish community structure in a tidal creek.
Spach, H L; Santos, C; Godefroid, R S; Nardi, M; Cunha, F
2004-05-01
The fish assemblage in a mangrove tidal creek was studied in monthly collections between August 1998 and July 1999 in the quadrature low tide and high tide, using a fyke net of 30 m x 1.5 m and meshes of 8 and 10 mm. Simultaneously with the biological collections, temperature, salinity, pH, water transparency, and current speed data were obtained. The collections resulted in the capture of 36,873 fish representing 22 families and 52 species. Immature individuals abounded (63.8%), and among the adult specimens there was a larger number of females. The species Anchoa parva, Harengula clupeola, Genidens genidens, and Bairdiella ronchus, contributed to 84.9% of the total capture of fish, however the contribution in mass was of 55.2%, indicating a predominance of small individuals. A smaller number of fish and species seem to occupy the area in the period between August and December, in comparison to the period between February and July, when the larger aggregations appear, mainly of the species Anchoa parva, Harengula clupeola, Opisthonema oglinum, Genidens genidens, Diapterus rhombeus, and Bairdiella ronchus. The environmental factors, pH, water transparency, and rainfall seem to have an influence in the structure of the observed biological patterns.
Choi, Minkyu; Furlong, Edward T.; Moon, Hyo-Bang; Yu, Jun; Choi, Hee-Gu
2011-01-01
Nonylphenolic compounds (NPs), coprostanol (COP), and cholestanol, major contaminants in industrial and domestic wastewaters, were analyzed in creek water, wastewater treatment plant (WWTP) effluent, and sediment samples from artificial Lake Shihwa and its vicinity, one of the most industrialized regions in Korea. We also determined mass discharge of NPs and COP, a fecal sterol, into the lake, to understand the linkage between discharge and sediment contamination. Total NP (the sum of nonylphenol, and nonylphenol mono- and di-ethoxylates) were 0.32–875 μg L-1 in creeks, 0.61–87.0 μg L-1 in WWTP effluents, and 29.3–230 μg g-1 TOC in sediments. Concentrations of COP were 0.09–19.0 μg L-1 in creeks, 0.11–44.0 μg L-1 in WWTP effluents, and 2.51–438 μg g-1 TOC in sediments. The spatial distributions of NPs in creeks and sediments from the inshore region were different from those of COP, suggesting that Lake Shihwa contamination patterns from industrial effluents differ from those from domestic effluents. The mass discharge from the combined outfall of the WWTPs, located in the offshore region, was 2.27 kg d-1 for NPs and 1.00 kg d-1 for COP, accounting for 91% and 95% of the total discharge into Lake Shihwa, respectively. The highest concentrations of NPs and COP in sediments were found in samples at sites near the submarine outfall of the WWTPs, indicating that the submarine outfall is an important point source of wastewater pollution in Lake Shihwa.
Diatom-driven recolonization of microbial mat-dominated siliciclastic tidal flat sediments.
Pan, Jerónimo; Cuadrado, Diana G; Bournod, Constanza N
2017-10-01
Modern microbial mats and biofilms play a paramount role in sediment biostabilization. When sporadic storms affect tidal flats of Bahía Blanca Estuary, the underlying siliciclastic sediment is exposed by physical disruption of the mat, and in a few weeks' lapse, a microbial community re-establishes. With the objective of studying colonization patterns and the ecological succession of microorganisms at the scale of these erosional structures, these were experimentally made and their biological recolonization followed for 8 weeks, with replication in winter and spring. Motile pennate diatoms led the initial colonization following two distinct patterns: a dominance by Cylindrotheca closterium in winter and by naviculoid and nitzschioid diatoms in spring. During the first 7 days, cell numbers increased 2- to 17-fold. Cell densities further increased exhibiting sigmoidal community growth, reaching 2.9-8.9 × 106 cells cm-3 maxima around day 30; centric diatoms maintained low densities throughout. In 56 days after removal of the original mat, filamentous cyanobacteria that dominate mature mats did not establish a significant biomass, leading to the rejection of the hypothesis that cyanobacteria would drive the colonization. The observed dominance of pennate diatoms is attributed to extrinsic factors determined by tidal flooding, and intrinsic ones, e.g. motility, nutrient affinity and high growth rate. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Hu, Hao; Wei, Taoyuan; Yang, Zhongyong; Hackney, Christopher R.; Parsons, Daniel R.
2018-05-01
It has long been highlighted that important feedbacks exist between river bed morphology, sediment transport and the turbulent flow field and that these feedbacks change in response to forcing mechanisms. However, our current understanding of bedform dynamics is largely based on studies of steady flow environments and cohesionless bed conditions. Few investigations have been made under rapidly changing flows. Here, we examine flow and sediment dynamics over low-angle dunes in unsteady flows in the Changjiang (Yangtze) Estuary, China. Topography, flow and sediment data were collected over a reach ca 1.8 km long through a semi-diurnal tidal cycle in a moderate tide of flood season. The results show that: (1) roughness length derived from the upper flow changes little with the flow reversing and displays the same value on both the ebb and flood tide. Moreover, the variability of individual bedform features plays an important role in roughness length variation. (2) Shear stress over the crest of low-angle dunes roughly represents the total spatially averaged stress over dunes in this study area, which has significant implications for advancing numerical models. (3) Changes in morphology, flow and sediment dynamics over dunes through time reveal how low-angle dunes evolve within a tidal cycle. (4) The clockwise hysteresis loops between flow dynamics and bedform features (height and aspect ratio) are also observed. The combination of suspended sediment transport and bedload transport on dune transformation and migration attributes to the clockwise hysteresis. The specific sediment composition of the riverbed, in some extent, affects the mechanism of sediment transport related to the exchange between suspended sediment and riverbed, but further investigation is needed to figure out the mechanism behind this for extended series of tides, such as spring/neap tide and tides in flooding and dry season.
Morphodynamics of the Manyema tidal delta at Kunduchi, Tanzania ...
African Journals Online (AJOL)
The prevailing northward longshore drift of beach sand on the northern part of Msasani Bay, north of Dar es Salaam, is interrupted at Kunduchi by the tidal flushing of Manyema Creek, a mangrove ecosystem partially developed for salt production. Shoreline changes around the creek mouth in recent decades have eroded ...
Yang, Zhongyong; de Swart, Huib E.; Cheng, Heqin; Jiang, Chenjuan; Valle-Levinson, Arnoldo
2014-01-01
The effect of the joint action of M2 and M4 tidal flow, residual flow and spatial settling lag on the lateral entrapment of sediment is examined in tidally dominated estuaries with an idealized model that assumes along-estuary uniform conditions. Approximate solutions are obtained for arbitrary
Radioactive and radiogenic isotopes in sediments from Cooper Creek, Western Arnhem Land
Energy Technology Data Exchange (ETDEWEB)
Frostick, A. [Charles Darwin University, Darwin, NT 0909 (Australia); ERISS, GPO Box 461, Darwin, NT 0801 (Australia)], E-mail: alison.frostick@cdu.edu.au; Bollhoefer, A. [ERISS, GPO Box 461, Darwin, NT 0801 (Australia); Parry, D.; Munksgaard, N. [Charles Darwin University, Darwin, NT 0909 (Australia); Evans, K. [ERISS, GPO Box 461, Darwin, NT 0801 (Australia)
2008-03-15
Protection of the environment post-mining is a key objective of rehabilitation, especially where runoff and erosion from rehabilitated mine sites could potentially lead to contamination of the surrounding land and watercourses. As part of an overall assessment of the success of rehabilitation at the former Nabarlek uranium (U) mine, an appraisal of stable lead (Pb) isotopes, radionuclides and trace metals within sediments and soils was conducted to determine the off site impacts from a spatial and temporal perspective. The study found localised areas on and adjacent to the site where soils had elevated levels of trace metals and radionuclides. Lead isotope ratios are highly radiogenic in some samples, indicating the presence of U-rich material. There is some indication that erosion products with more radiogenic Pb isotope ratios have deposited in sediments downstream of the former ore body. However, there is no indication that the radiogenic erosion products found on the mine site at present have significantly contaminated sediments further downstream of Cooper Creek.
Radioactive and radiogenic isotopes in sediments from Cooper Creek, Western Arnhem Land
International Nuclear Information System (INIS)
Frostick, A.; Bollhoefer, A.; Parry, D.; Munksgaard, N.; Evans, K.
2008-01-01
Protection of the environment post-mining is a key objective of rehabilitation, especially where runoff and erosion from rehabilitated mine sites could potentially lead to contamination of the surrounding land and watercourses. As part of an overall assessment of the success of rehabilitation at the former Nabarlek uranium (U) mine, an appraisal of stable lead (Pb) isotopes, radionuclides and trace metals within sediments and soils was conducted to determine the off site impacts from a spatial and temporal perspective. The study found localised areas on and adjacent to the site where soils had elevated levels of trace metals and radionuclides. Lead isotope ratios are highly radiogenic in some samples, indicating the presence of U-rich material. There is some indication that erosion products with more radiogenic Pb isotope ratios have deposited in sediments downstream of the former ore body. However, there is no indication that the radiogenic erosion products found on the mine site at present have significantly contaminated sediments further downstream of Cooper Creek
Sediment microalgae play an important role in nutrient cycling and are important primary producers in the food web in Pacific Northwest estuaries. This study examines the effects of nitrogen addition to benthic microalgae in tidal wetlands of Yaquina Bay estuary on the Oregon c...
Sediment budget for Murder Creek, Georgia, USA, from Pu239+240 - determined soil erosion rates
Stubblefield, A. P.; Matissoff, G.; Ketterer, M. E.; Whiting, P. J.
2005-12-01
Soil inventories of the radionuclides Cs137 and Pb210 have been used in a variety of environments as indicators for erosion and depositional processes. Development of sediment budgets for entire watersheds from radionuclide data has been somewhat constrained because limited sample numbers may not adequately characterize the wide range of geomorphic conditions and land uses found in heterogeneous environments. The measurement of Pu239+240 shows great potential for developing quantitative watershed sediment budgets. With inductively-coupled plasma mass spectrometry, hundreds of samples may be processed in dramatically shorter times than the gamma spectrometry method used for Cs137 or alpha spectrometry method used for Pb210. We collected surface soil samples from Murder Creek in the Piedmont region of Georgia, USA, to compare Pu239+240 inventories with Cs137 and Pb210 inventories for a range of land uses in a predominantly forested watershed. Excellent correlations were found for radionuclide inventories (r2 =0.88, n = 38) and high resolution (4 mm) depth profiles. The second objective was to generate a sediment budget using the full Pu239+240 dataset (n = 309). Average Pu239+240 inventories were 70.0 Bq/m2 for hardwood forest, 60.0 Bq/m2 for pine plantation, 65.1 Bq/m2 for pine forest, 66.7 Bq/m2 for row crop agriculture and 67.9 Bq/m2 for pasture. The sediment budget will be constructed by converting inventories into site-specific erosion rates. Erosion rates will be scaled up to the watershed scale using GIS coverages of land use, soil, slope, and slope position. Results will be compared with Murder Creek sediment budgets in the scientific literature generated from RUSLE erosion modeling, USGS monitoring networks and reservoir sedimentation.
Annual sediment flux estimates in a tidal strait using surrogate measurements
Ganju, N.K.; Schoellhamer, D.H.
2006-01-01
Annual suspended-sediment flux estimates through Carquinez Strait (the seaward boundary of Suisun Bay, California) are provided based on surrogate measurements for advective, dispersive, and Stokes drift flux. The surrogates are landward watershed discharge, suspended-sediment concentration at one location in the Strait, and the longitudinal salinity gradient. The first two surrogates substitute for tidally averaged discharge and velocity-weighted suspended-sediment concentration in the Strait, thereby providing advective flux estimates, while Stokes drift is estimated with suspended-sediment concentration alone. Dispersive flux is estimated using the product of longitudinal salinity gradient and the root-mean-square value of velocity-weighted suspended-sediment concentration as an added surrogate variable. Cross-sectional measurements validated the use of surrogates during the monitoring period. During high freshwater flow advective and dispersive flux were in the seaward direction, while landward dispersive flux dominated and advective flux approached zero during low freshwater flow. Stokes drift flux was consistently in the landward direction. Wetter than average years led to net export from Suisun Bay, while dry years led to net sediment import. Relatively low watershed sediment fluxes to Suisun Bay contribute to net export during the wet season, while gravitational circulation in Carquinez Strait and higher suspended-sediment concentrations in San Pablo Bay (seaward end of Carquinez Strait) are responsible for the net import of sediment during the dry season. Annual predictions of suspended-sediment fluxes, using these methods, will allow for a sediment budget for Suisun Bay, which has implications for marsh restoration and nutrient/contaminant transport. These methods also provide a general framework for estimating sediment fluxes in estuarine environments, where temporal and spatial variability of transport are large. ?? 2006 Elsevier Ltd. All rights
Li, Michael Z.; Shaw, John; Todd, Brian J.; Kostylev, Vladimir E.; Wu, Yongsheng
2014-07-01
Multibeam sonar mapping and geophysical and geological groundtruth surveys were coupled with tidal current and sediment transport model calculations to investigate the sediment transport and formation processes of the complex seabed features off the Cape Split headland in the upper Bay of Fundy. The Cape Split banner bank, composed of coarse to very coarse sand, is a southwest-northeast oriented, large tear-drop shaped sand body with superimposed sand waves that show wavelengths from 15 to 525 m and heights from 0.5 to 19 m. Isolated and chains of barchan dunes occur on top of a shadow bank to the southeast of the banner bank. The barchan dunes are composed of well-sorted medium sand and are oriented northwest-southeast. Their mean height and width are 1.5 and 55 m, respectively. A gravel bank, with an elongated elliptical shape and west-east orientation, lies in the Minas Passage erosional trough east of the headland to form the counterpart to the sandy Cape Split banner bank. The southern face is featureless but the northern face is covered by gravel megaripples. Tidal model predictions and sediment transport calculations show that the formation of the banner bank and the gravel bank are due to the development of the transient counter-clockwise and clockwise tidal eddies respectively to the west and east of the headland. The formation of barchan dunes is controlled by the nearly unidirectional flow regime in outer Scots Bay. Sand waves on the flanks of the Cape Split banner bank show opposite asymmetry and the barchan dunes are asymmetric to the northeast. The tidal current and sediment transport predictions corroborate bedform asymmetry to show that sand wave migration and net sediment transport is to southwest on the northern flank of the banner bank but to northeast on the southern bank. Long-term migration of the Scots Bay barchan dunes is to the northeast. Spring-condition tidal currents can cause frequent mobilization and high-stage transport over the
Zhou, Zeng; Ye, Qinghua; Coco, Giovanni
2016-07-01
We develop a biomorphodynamic model to investigate sediment and vegetation dynamics on a schematic intertidal flat characterized by an initially well-mixed sand-mud mixture. Major interactions between tides, wind waves, salt marshes, sediment transport and sea level rise (SLR) are taken into account. For a bare flat under only tidal action, the model predicts a convex cross-shore profile with the surficial distribution of mud and sand on the upper and lower part of the intertidal flat, respectively. When wind waves are strong, the intertidal flat is highly eroded resulting in a concave profile near the high water mark. This behavior is pronouncedly altered when the intertidal flat is vegetated with the presence of salt marshes. Numerical results suggest that a considerable amount of mud can still remain in the vegetated region even when wave action is strong. A steeper transition zone forms at the boundary between salt marshes and bare flats because of the differential sediment deposition in the two neighboring regions. The inclusion of wind waves is found to considerably enhance the size of the marsh-edge transition zone. For the numerical experiments designed in this study, the profile shape and sediment sorting behavior of tidal flats are not significantly modified by a gradual rising sea level. However, the impacts of SLR on vegetated tidal flats are still manifold: (a) driving the landward migration of intertidal zone and salt marshes; (b) enhancing sediment erosion on intertidal flats; and (c) drowning salt marshes under limited sediment supply with the constrain of seawalls. Finally, model results suggest that organic carbon accumulation on marshlands may be enhanced with an increasing SLR rate provided that salt marshes are not drowned.
Bouchet, Sylvain; Tessier, Emmanuel; Monperrus, Mathilde; Bridou, Romain; Clavier, Jacques; Thouzeau, Gerard; Amouroux, David
2011-05-01
The elemental mercury evasion from non-impacted natural areas is of significant importance in the global Hg cycle due to their large spatial coverage. Intertidal areas represent a dynamic environment promoting the transformations of Hg species and their subsequent redistribution. A major challenge remains in providing reliable data on Hg species variability and fluxes under typical transient tidal conditions found in such environment. Field experiments were thus carried out to allow the assessment and comparison of the magnitude of the gaseous Hg fluxes at the three interfaces, sediment-water, sediment-atmosphere and water-atmosphere of a mesotidal temperate lagoon (Arcachon Bay, Aquitaine, France) over three distinct seasonal conditions. The fluxes between the sediment-water and the sediment-atmosphere interfaces were directly evaluated with field flux chambers, respectively static or dynamic. Water-atmosphere fluxes were evaluated from ambient concentrations using a gas exchange model. The fluxes at the sediment-water interface ranged from -5.0 to 5.1 ng m(-2) h(-1) and appeared mainly controlled by diffusion. The occurrence of macrophytic covers (i.e.Zostera noltii sp.) enhanced the fluxes under light radiations. The first direct measurements of sediment-atmosphere fluxes are reported here. The exchanges were more intense and variable than the two other interfaces, ranging between -78 and 40 ng m(-2) h(-1) and were mostly driven by the overlying atmospheric Hg concentrations and superficial sediment temperature. The exchanges between the water column and the atmosphere, computed as a function of wind speed and gaseous mercury saturation ranged from 0.4 to 14.5 ng m(-2) h(-1). The flux intensities recorded over the intertidal sediments periodically exposed to the atmosphere were roughly 2 to 3 times higher than the fluxes of the other interfaces. The evasion of elemental mercury from emerged intertidal sediments is probably a significant pathway for Hg evasion in
Sediment budgets, transport, and depositional trends in a large tidal delta
Morgan, Tara; Wright, Scott A.
2016-01-01
The Sacramento-San Joaquin Delta is the largest delta on the west coast of the United States. It is formed where the confluence of California’s two largest rivers (the Sacramento and San Joaquin) meet the ocean tides and has a significant physical gradient from fluvial to tidal. It is a semidiurnal system (two high and two low tides per day). Today, the Delta is one of the most manipulated in the United States. Once composed of many shallow, meandering and braided dendritic channels and dead-end sloughs and wetlands, it is now a network of leveed canals moving clear water around subsided islands. It historically has supported a biologically diverse tidal wetland complex, of which only 3% remains today (Whipple et al., 2012). It has also witnessed a collapse in the native fish populations. The Delta provides critical habitat for native species, however the hydrology and water quality are complicated by manipulations and diversions to satisfy multiple statewide objectives. Today water managers face co-equal goals of water supply to Californians and maintenance of ecosystem health and function. The Delta is a hub for both a multi-hundred-million dollar agricultural industry and a massive north-to-south water delivery system, supplying the primary source of freshwater to Central Valley farmers and drinking water for two-thirds of California’s population. Large pump facilities support the water demand and draw water from the Delta, further altering circulation patterns and redirecting the net flow toward the export facilities (Monsen et al., 2007). Fluvial sedimentation, along with organic accumulation, creates and sustains the Delta landscape. Hydraulic mining for gold in the watershed during the late 1800s delivered an especially large sediment pulse to the Delta. More recently, from 1955 to the present, a significant sediment decline has been observed that is thought to have been caused mostly by the construction of water storage reservoirs that trap the upstream
Koo, Bon Joo; Kwon, Kae Kyoung; Hyun, Jung-Ho
2007-11-01
We quantified the increase in the sediment-water interface created by the burrowing activities of the resident macrofaunal community and its variation with respect to the physical conditions of the habitat on a tidal fat. We investigated environmental factors and dimensions of macrofaunal burrows with respect to tidal height and vegetation during spring and summer at three sites. A resin-casting method was used to quantify the dimensions of all burrows at each site. The dimensions of macrofaunal burrows varied both temporally and spatially and the increase in the sediment-water interface reached a maximum of 311%, ranging from 20 to 255% under different habitat conditions. The sediment-water interface depended on the duration of exposure resulting from tidal height, increased temperatures resulting from seasonality, and marsh plant density. Burrows were deeper and more expansive at both higher tidal levels and higher temperatures in summer. Burrow dimensions were sharply reduced with the disappearance of adult macrofauna in areas where the roots of the marsh plant Suaeda japonica were dense. The significance of this study lies in quantifying the burrow dimensions of the entire macrofaunal community, rather than just a single population, and confirming their spatial and temporal variation with respect to physical conditions of the habitat. Environmental factors responsible for variation in burrow dimensions are discussed.
Wren, A.; Xu, K.; Ma, Y.; Sanger, D.; Van Dolah, R.
2014-12-01
Bottom-mounted instrumentation was deployed at two sites on an ebb tidal delta to measure hydrodynamics, sediment transport, and seabed elevation. One site ('borrow site') was 2 km offshore and used as a dredging site for beach nourishment of nearby Hilton Head Island in South Carolina, and the other site ('reference site') was 10 km offshore and not directly impacted by the dredging. In-situ time-series data were collected during two periods after the dredging: March 15 - June 12, 2012('spring') and August 18 - November 18, 2012 ('fall'). At the reference site directional wave spectra and upper water column current velocities were measured, as well as high-resolution current velocity profiles and suspended sediment concentration profiles in the Bottom Boundary Layer (BBL). Seabed elevation and small-scale seabed changes were also measured. At the borrow site seabed elevation and near-bed wave and current velocities were collected using an Acoustic Doppler Velocimeter. Throughout both deployments bottom wave orbital velocities ranged from 0 - 110 m/s at the reference site. Wave orbital velocities were much lower at the borrow site ranging from 10-20 cm/s, as wave energy was dissipated on the extensive and rough sand banks before reaching the borrow site. Suspended sediment concentrations increased throughout the BBL when orbital velocities increased to approximately 20 cm/s. Sediment grain size and critical shear stresses were similar at both sites, therefore, re-suspension due to waves was less frequent at the borrow site. However, sediment concentrations were highly correlated with the tidal cycle at both sites. Semidiurnal tidal currents were similar at the two sites, typically ranging from 0 - 50 cm/s in the BBL. Maximum currents exceeded the critical shear stress and measured suspended sediment concentrations increased during the first hours of the tidal cycle when the tide switched to flood tide. Results indicate waves contributed more to sediment mobility at
Environmental consequences of tidal power in a hyper-tidal muddy regime: the Severn estuary
International Nuclear Information System (INIS)
Kirby, R.
1997-01-01
Muddy hyper-tidal regimes, such as the Severn Estuary in the UK, are especially difficult for plants and animals. The difficulties stem from the semi-diurnal and semi-lunar energy fluctuations. On spring tides entrained fine sediment induces elevated suspended sediment concentrations such that photosynthesis is inhibited. On neap tides much of the entrained fine sediment is deposited on the sub-tidal bed over periods of several days to form ephemeral dense layers, which reach in excess of 100 G/l and rapidly become anaerobic on stagnation. Such occasional bed faunas as develop are characterised by very large numbers of immature individuals of a few species. One of the few organisms able to cope with the extreme conditions is the siliceous reef-building worn Sabellaria. Arising from the long term suppression in its calcareous fauna, erosion and winnowing of these Holocene clays fails to give rise to lag shell deposits, called chenier ridges, found elsewhere in eroding muddy inter-tidal systems. A tidal power barrage would shift the regime from hyper-tidal to macro-tidal decrease in turbidity would permit photosynthesis and phytoplankton growth, so stimulating the higher food chain. Ironically, perhaps, cleaning up the sewage discharges in the estuary, in the absence of barrage construction would lead to a wading bird crash whereas barrage construction would lead to an improved carrying capacity. (author)
Sedimentation rate and lateral migration of tidal channels in the Lagoon of Venice (Northern Italy)
Donnici, Sandra; Madricardo, Fantina; Serandrei-Barbero, Rossana
2017-11-01
Tidal channels are crucial for the functioning of highly valuable coastal environments, such as estuaries and lagoons. Their properties, however, are currently less understood than those of river systems. To elucidate their past behaviour, an extensive geophysical investigation was performed to reconstruct the evolution of channels and tidal surfaces in the central part of the Lagoon of Venice (Italy) over the past 5000 years. Comparing high-spatial-resolution acoustic data and sedimentary facies analyses of 41 cores, 29 of which were radiocarbon dated, revealed the sedimentation rates in different lagoonal environments and allowed the migration of two large meanders to be reconstructed. The average sedimentation rate of the study succession in the different sedimentary environments was 1.27 mm yr-1. The lateral migration rates were 13-23 m/century. This estimate is consistent with the lateral migration rates determined by comparing aerial photographs of recent channels. Comparing the buried channels with historical and current maps showed that, in general, the number of active channels is now reduced. Their morphology was sometimes simplified by artificial interventions. An understanding of the impact of the artificial interventions over time is useful for the management and conservation of tidal environments, particularly for the Lagoon of Venice, where management authorities are currently debating the possible deepening and rectification of large navigation channels.
Suspended sediment load in the tidal zone of an Indonesian river
Directory of Open Access Journals (Sweden)
F. A. Buschman
2012-11-01
Full Text Available Forest clearing for reasons of timber production, open pit mining and the establishment of oil palm plantations generally results in excessively high sediment loads in tropical rivers. The increasing sediment loads pose a threat to coastal marine ecosystems, such as coral reefs. This study presents observations of suspended sediment loads in the Berau River (Kalimantan, Indonesia, which debouches into a coastal ocean that is a preeminent center of coral diversity. The Berau River is relatively small and drains a mountainous, still relatively pristine basin that receives abundant rainfall. In the tidal zone of the Berau River, flow velocity was measured over a large part of the river width using a horizontal acoustic Doppler current profiler (HADCP. Surrogate measurements of suspended sediment concentration were taken with an optical backscatter sensor (OBS. Averaged over the 6.5 weeks covered by the benchmark survey period, the suspended sediment load was estimated at 2 Mt yr−1. Based on rainfall-runoff modeling though, the river discharge peak during the survey was supposed to be moderate and the yearly averaged suspended sediment load is most likely somewhat higher than 2 Mt yr−1. The consequences of ongoing clearing of rainforest were explored using a plot-scale erosion model. When rainforest, which still covered 50–60% of the basin in 2007, is converted to production land, soil loss is expected to increase with a factor between 10 and 100. If this soil loss is transported seaward as suspended sediment, the increase in suspended sediment load in the Berau River would impose a severe stress on this global hotspot of coral reef diversity.
Balanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes
Rosencranz, Jordan A.; Ganju, Neil K.; Ambrose, Richard F.; Brosnahan, Sandra M.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; MacDonald, Glen M.; Takekawa, John Y.; Thorne, Karen M.
2016-01-01
Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km2 salt marsh (Seal Beach) and a less modified 1-km2marsh (Mugu) with fluvial sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12,000 and 8800 kg in a western and eastern channel. Western channel storm imports offset 8700 kg exported during 2 months of dry weather, while eastern channel storm imports augmented 9200 kg imported during dry weather. During the storm at Mugu, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1–2 mm near creek levees. An exceptionally high tide sequence yielded 4.4 g/s mean sediment flux, importing 1700 kg: 20 % of Mugu’s dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are geomorphically stable during dry weather conditions. Results suggest storms and high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea level rise scenarios, results suggest that balanced sediment fluxes lead to marsh elevational instability based on estimated mineral sediment deficits.
Wang, J.; Xu, K.; Restreppo, G. A.; Bentley, S. J.; Meng, X.; Zhang, X.
2017-12-01
Due to global sea level rise, local subsidence and sediment deficit, the Mississippi River (MR) deltaic plain has lost a total of 25% of coastal Louisiana's wetlands during the last century, leading to huge losses of ecological services, economic and social crises. Ecosystem-based restoration strategies which rely on coastal system processes and feedbacks are urgently needed. Understanding linkages between estuarine and coastal systems and the adjacent marshlands will help the designing strategies. To investigate bay hydrodynamics and its impacts on the adjacent micro-tidal wetland stability, hourly measurements of wave, tidal current, and benthic sediment concentration in summer, winter, and spring of 2015-2016 were conducted in Fourleague Bay, Louisiana, USA. The bay-marsh system has been stable for almost 80 years under high relative sea level rising rate, which is 11 km southeast of the Atchafalaya River mouth, with a water depth of 1-3 m. High-temporal resolution data indicate that benthic sediment resuspension is mainly caused by wind-driven waves with a dominant periodicity of 4.8 d. The sediment flux reaches 28 g·m-1·s-1 per unit depth in cm during the events. Net sediment transport is northwestward in summer, and southeastward in winter and spring. Sediment flux available for surrounding marsh varies from 0-500 g·m-1·s-1. An optimal inundation depth of 50 cm is estimated by the equilibrium wetland elevation change model under high relative sea level rising rate of 1.57 cm·yr-1. Seasonal variations of river discharge and wind direction (particularly speeds >3 m·s-1) greatly impact potential sediment contribution from bay to the surrounding wetlands. Three sediment transport regimes are concluded based on the seasonal variations of river discharge and wind direction: the `bypassing' season, the resuspension-accumulation season, and the combined `bypassing' and resuspension-accumulation season. The bay hydrodynamic processes and their impacts on the
Mary Ann Madej; Greg Bundros; Randy Klein
2012-01-01
Revisions to the California Forest Practice Rules since 1974 were intended to increase protection of water quality in streams draining timber harvest areas. The effects of improved timber harvesting methods and road designs on sediment loading are assessed for the Panther Creek basin, a 15.4 km2 watershed in Humboldt County, north coastal...
DEFF Research Database (Denmark)
Stark, Nina; Hanff, Henrik; Svenson, Christian
2011-01-01
In-situ geotechnical measurements of surface sediments were carried out along large subaqueous dunes in the Knudedyb tidal inlet channel in the DanishWadden Sea using a small free-falling penetrometer. Vertical profiles showed a typical stratification pattern with a resolution of ~1 cm depicting...... a thin surface layer of low sediment strength and a stiffer substratum below (quasi-static bearing capacity equivalent: 1–3 kPa in the top layer, 20–140 kPa in the underlying sediment; thickness of the top layer ca. 5–8 cm). Observed variations in the thickness and strength of the surface layer during...... a tidal cycle were compared to mean current velocities (measured using an acoustic Doppler current profiler, ADCP), high-resolution bathymetry (based on multibeam echo sounding, MBES) and qualitative estimates of suspended sediment distributions in the water column (estimated from ADCP backscatter...
Simmons, J.; Ruhl, L. S.
2017-12-01
Jason Simmons and Laura S. Ruhl As Earth's population continues to grow, is it expected that by the year 2030, sixty percent of all people will be housed in urban cities. Although these urban areas are of the utmost importance socially, culturally and economically, they also have an adverse impact on the geochemical makeup of the natural landscape. Rapid urbanization has profound hydrological, chemical, physical, and ecological impacts on watersheds near urban areas. Trace metals, and other organic and inorganic contaminants from industrialization, car exhaust, overflow of sewage lines, and excess storm drain runoff are found in this surface water. In Little Rock, Arkansas, runoff from seventy-three percent of the city's surface area empties into Fourche Creek, then its urban wetlands, before it is further transported to the Arkansas River. Previous studies have revealed that the Fourche Creek wetlands mitigate flooding and remove contaminants from the water column. In this study, we examined the effects of urbanization by examining the geochemical makeup of the wetland sediment that drains most of Little Rock. Sediment samples were collected along transects of Fourche Creek at three locations, beginning at the water's edge and moving out distances between seventy to one hundred feet into the wetland. Sediments were dried, homogenized, and then sieved for grain size distribution. Leaching experiments were performed to determine the trace element concentration adsorbed to the surface, which could be easily mobilized. In these experiments, ultrapure deionized water and homogenized soil were combined in centrifuge tubes at a 10:1 liquid to solid ratio, and rotated for twenty-four hours allowing the mixture to properly combine and react. The leachate was filtered, then analyzed using Ion Chromatography (IC) to determine cations and anions, and ICPMS to determine trace metals present in the soil. Results were compiled, and a map was created showing grain sizes present
Rytuba, James J.; Hothem, Roger L.; May, Jason T.; Kim, Christopher S.; Lawler, David; Goldstein, Daniel; Brussee, Brianne E.
2009-01-01
The Helen, Research, and Chicago mercury (Hg) deposits are among the youngest Hg deposits in the Coast Range Hg mineral belt and are located in the southwestern part of the Clear Lake volcanic field in Lake County, California. The mine workings and tailings are located in the headwaters of Dry Creek. The Helen Hg mine is the largest mine in the watershed having produced about 7,600 flasks of Hg. The Chicago and Research Hg mines produced only a small amount of Hg, less than 30 flasks. Waste rock and tailings have eroded from the mines, and mine drainage from the Helen and Research mines contributes Hg-enriched mine wastes to the headwaters of Dry Creek and contaminate the creek further downstream. The mines are located on federal land managed by the U.S. Bureau of Land Management (USBLM). The USBLM requested that the U.S. Geological Survey (USGS) measure and characterize Hg and geochemical constituents in tailings, sediment, water, and biota at the Helen, Research, and Chicago mines and in Dry Creek. This report is made in response to the USBLM request to conduct a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA - Removal Site Investigation (RSI). The RSI applies to removal of Hg-contaminated mine waste from the Helen, Research, and Chicago mines as a means of reducing Hg transport to Dry Creek. This report summarizes data obtained from field sampling of mine tailings, waste rock, sediment, and water at the Helen, Research, and Chicago mines on April 19, 2001, during a storm event. Further sampling of water, sediment, and biota at the Helen mine area and the upper part of Dry Creek was completed on July 15, 2003, during low-flow conditions. Our results permit a preliminary assessment of the mining sources of Hg and associated chemical constituents that could elevate levels of monomethyl Hg (MMeHg) in the water, sediment, and biota that are impacted by historic mining.
A mangrove creek restoration plan utilizing hydraulic modeling.
Marois, Darryl E; Mitsch, William J
2017-11-01
Despite the valuable ecosystem services provided by mangrove ecosystems they remain threatened around the globe. Urban development has been a primary cause for mangrove destruction and deterioration in south Florida USA for the last several decades. As a result, the restoration of mangrove forests has become an important topic of research. Using field sampling and remote-sensing we assessed the past and present hydrologic conditions of a mangrove creek and its connected mangrove forest and brackish marsh systems located on the coast of Naples Bay in southwest Florida. We concluded that the hydrology of these connected systems had been significantly altered from its natural state due to urban development. We propose here a mangrove creek restoration plan that would extend the existing creek channel 1.1 km inland through the adjacent mangrove forest and up to an adjacent brackish marsh. We then tested the hydrologic implications using a hydraulic model of the mangrove creek calibrated with tidal data from Naples Bay and water levels measured within the creek. The calibrated model was then used to simulate the resulting hydrology of our proposed restoration plan. Simulation results showed that the proposed creek extension would restore a twice-daily flooding regime to a majority of the adjacent mangrove forest and that there would still be minimal tidal influence on the brackish marsh area, keeping its salinity at an acceptable level. This study demonstrates the utility of combining field data and hydraulic modeling to aid in the design of mangrove restoration plans.
Digital Repository Service at National Institute of Oceanography (India)
Kulkarni, V.A.; Naidu, V.S.; Jagtap, T.G.
Estuaries and tidal creeks, harboring mangroves particularly, face tremendous anthropogenic pressures. Expansion of mega cities and the thermal power plants are generally proposed in the vicinity of estuaries and creek, due to the feasibility...
DEFF Research Database (Denmark)
Madsen, Anni T.; Murray, Andrew S.; Jain, Mayank
2011-01-01
The rates of post-depositional mixing by bioturbation have been investigated using Optically Stimulated Luminescence (OSL) dating in two sediment cores (BAL2 and BAL5), retrieved from a sandy tidal flat in the Danish part of the Wadden Sea. A high-resolution chronology, consisting of thirty-six OSL...
Directory of Open Access Journals (Sweden)
Peng Zhang
2014-03-01
Full Text Available Numerical models being one of the major tools for sediment dynamic studies in complex coastal waters are now benefitting from remote sensing images that are easily available for model inputs. The present study explored various methods of integrating remote sensing ocean color data into a numerical model to improve sediment transport prediction in a tide-dominated bay in Hong Kong, Deep Bay. Two sea surface sediment datasets delineated from satellite images from the Moderate Resolution Imaging Spectra-radiometer (MODIS were assimilated into a coastal ocean model of the bay for one tidal cycle. It was found that remote sensing sediment information enhanced the sediment transport model ability by validating the model results with in situ measurements. Model results showed that root mean square errors of forecast sediment both at the surface layer and the vertical layers from the model with satellite sediment assimilation are reduced by at least 36% over the model without assimilation.
Directory of Open Access Journals (Sweden)
S. L. Yang
2004-01-01
Full Text Available Observations of fair weather currents and suspended sediment concentrations (SSC were made using an acoustic Doppler current profiler and two YSI turbidity sensors over a neap to spring time cycle at a site near the inner mouth of a semi-enclosed mesotidal-macrotidal embayment (Jiaozhou Bay to examine the influence of tidal dynamics on concentration and transport of suspended sediment. During the investigation, SSC varied from about 3 to 16 mg L–1 at the surface and about 6 to 40 mg L–1 close to the bed, while the current velocity reached 79 cm s–1 at the surface and 61 cm s–1 near the bed. SSC was tidally cyclic. The near-bed instantaneous SSC was closely related to current velocity with almost no time lag, indicating that the variability of SSC was governed by current-induced settling/resuspension. At the surface, however, instantaneous SSC was poorly related to instantaneous current velocity because the peak SSC tended to occur around ebb slack water. This suggests that the surface SSC was controlled by horizontal advection from landward higher concentration areas. Both at the surface and near the bed, on the other hand, tidally-averaged SSC was well correlated to tidal range and current speed. Current velocity and SSC were flood-dominated for all the tides investigated, which resulted in significant landward residual suspended sediment transport at the study site. The observed flood dominance was mainly attributed to the location of the study site on the landward side of the bay’s inlet where flow separation is favoured during flood tide. It was concluded that tides are the dominant hydrodynamic component controlling the variability of SSC during fair weather at the study area. Keywords: sediment, concentration, suspension, advection, currents, shoalling effect, Jiaozhou Bay, China
International Nuclear Information System (INIS)
Ledgerwood, F.K.; Larmour, R.A.; Mitchell, P.I.; Leon Vintro, L.; Ryan, R.W.
1999-01-01
Fine-grained surface (0-2 cm) sediment was collected at an inter-tidal site (Mahee Island) in Strangford Lough, on the NE coast of Ireland in September 1997. The sediment was wet-sieved into standard sized fractions using Endecott test sieves and the fractions assayed for 137 Cs, 239,240 Pu and 241 Am content. Sub-samples of each fraction were measured with a Malvern 2600 laser diffraction analyser, which confirmed that >90% of the particles in each fraction was in the defined size range
Directory of Open Access Journals (Sweden)
Carol Wilson
2017-12-01
Full Text Available Since the 1960s, ~5000 km2 of tidal deltaplain in southwest Bangladesh has been embanked and converted to densely inhabited, agricultural islands (i.e., polders. This landscape is juxtaposed to the adjacent Sundarbans, a pristine mangrove forest, both well connected by a dense network of tidal channels that effectively convey water and sediment throughout the region. The extensive embanking in poldered areas, however, has greatly reduced the tidal prism (i.e., volume of water transported through local channels. We reveal that >600 km of these major waterways have infilled in recent decades, converting to land through enhanced sedimentation and the direct blocking of waterways by embankments and sluice gates. Nearly all of the observed closures (~98% have occurred along the embanked polder systems, with no comparable changes occurring in channels of the Sundarbans (<2% change. We attribute most of the channel infilling to the local reduction of tidal prism in poldered areas and the associated decline in current velocities. The infilled channels account for ~90 km2 of new land in the last 40–50 years, the rate of which, ~2 km2/yr, offsets the 4 km2/yr that is eroded at the coast, and is equivalent to ~20% of the new land produced naturally at the Ganges-Brahmaputra tidal rivermouth. Most of this new land, called ‘khas’ in Bengali, has been reclaimed for agriculture or aquaculture, contributing to the local economy. However, benefits are tempered by the loss of navigable waterways for commerce, transportation, and fishing, as well as the forced rerouting of tidal waters and sediments necessary to sustain this low-lying landscape against rising sea level. A more sustainable delta will require detailed knowledge of the consequences of these hydrodynamic changes to support more scientifically-grounded management of water, sediment, and tidal energy distribution.
Water and sediment quality of the Lake Andes and Choteau Creek basins, South Dakota, 1983-2000
Sando, Steven Kent; Neitzert, Kathleen M.
2003-01-01
The Bureau of Reclamation has proposed construction of the Lake Andes/Wagner Irrigation Demonstration Project to investigate environmental effects of irrigation of glacial till soils substantially derived from marine shales. During 1983-2000, the U.S. Geological Survey collected hydrologic, water-quality, and sediment data in the Lake Andes and Choteau Creek Basins, and on the Missouri River upstream and downstream from Choteau Creek, to provide baseline information in support of the proposed demonstration project. Lake Andes has a drainage area of about 230 mi2 (square miles). Tributaries to Lake Andes are ephemeral. Water-level fluctuations in Lake Andes can be large, and the lake has been completely dry on several occasions. The outlet aqueduct from Lake Andes feeds into Garden Creek, which enters Lake Francis Case just upstream from Fort Randall Dam on the Missouri River. For Lake Andes tributary stations, calcium, magnesium, and sodium are approximately codominant among the cations, and sulfate is the dominant anion. Dissolved-solids concentrations typically range from about 1,000 mg/L (milligrams per liter) to about 1,700 mg/L. Major-ion concentrations for Lake Andes tend to be higher than the tributaries and generally increase downstream in Lake Andes. Proportions of major ions are similar among the different lake units (with the exception of Owens Bay), with calcium, magnesium, and sodium being approximately codominant among cations, and sulfate being the dominant anion. Owens Bay is characterized by a calcium sulfate water type. Dissolved-solids concentrations for Lake Andes typically range from about 1,400 to 2,000 mg/L. Whole-water nitrogen and phosphorus concentrations are similar among the Lake Andes tributaries, with median whole-water nitrogen concentrations ranging from about 1.6 to 2.4 mg/L, and median whole-water phosphorus concentrations ranging from about 0.5 to 0.7 mg/L. Whole-water nitrogen concentrations in Lake Andes are similar among the
The history of overbank sedimentation in the vicinity of Halfway Creek Marsh near La Crosse, Wisconsin, was examined during 2005-06 by the U.S. Geological Survey and University of Wisconsin-Madison as part of a broader study of sediment and nutrient loadings to the Upper Mississi...
On the sedimentation problems in water abstraction channels at power plant sites at tidal estuaries
International Nuclear Information System (INIS)
Jensen, J.; Arns, A.; Frank, T.; Meiswinkel, R.; Richei, A.
2010-01-01
The required cooling water supply of a nuclear power plant the required flow deepness in the water abstraction channels has to be provided. Since the abstraction channels are usually in main stream orientation of the river periodic sedimentation occur, that have to be removed by dredging techniques. Especially in tidal estuaries the complex flow situation induces transport mechanisms that have to be studied in order to develop cost saving and effective measures and procedures to reduce the sedimentation and pollutants deposition. The authors recommend experimental determinations of the sold material transport and numerical hydrodynamic transport modeling to identify the transport pathways.
Garcia, Ana Maria
2009-01-01
A study of the Currituck Sound was initiated in 2005 to evaluate the water chemistry of the Sound and assess the effectiveness of management strategies. As part of this study, the Soil and Water Assessment Tool (SWAT) model was used to simulate current sediment and nutrient loadings for two distinct watersheds in the Currituck Sound basin and to determine the consequences of different water-quality management scenarios. The watersheds studied were (1) Tull Creek watershed, which has extensive row-crop cultivation and artificial drainage, and (2) West Neck Creek watershed, which drains urban areas in and around Virginia Beach, Virginia. The model simulated monthly streamflows with Nash-Sutcliffe model efficiency coefficients of 0.83 and 0.76 for Tull Creek and West Neck Creek, respectively. The daily sediment concentration coefficient of determination was 0.19 for Tull Creek and 0.36 for West Neck Creek. The coefficient of determination for total nitrogen was 0.26 for both watersheds and for dissolved phosphorus was 0.4 for Tull Creek and 0.03 for West Neck Creek. The model was used to estimate current (2006-2007) sediment and nutrient yields for the two watersheds. Total suspended-solids yield was 56 percent lower in the urban watershed than in the agricultural watershed. Total nitrogen export was 45 percent lower, and total phosphorus was 43 percent lower in the urban watershed than in the agricultural watershed. A management scenario with filter strips bordering the main channels was simulated for Tull Creek. The Soil and Water Assessment Tool model estimated a total suspended-solids yield reduction of 54 percent and total nitrogen and total phosphorus reductions of 21 percent and 29 percent, respectively, for the Tull Creek watershed.
Kenyon, P. M.; Kassem, D.; Olin, A.; Nunez, J.; Smalling, A.
2005-05-01
Inwood Hill Park is located on the northern tip of Manhattan and has been extensively modified over the years by human activities. In its current form, it has a backbone of exposed or lightly covered bedrock along the Hudson River, adjacent to a flat area with two tidal inlets along the northern shore of Manhattan. The tidal motions in the inlets are expected to drive corresponding fluctuations in the water table along the borders of the inlets. In the Fall of 2002, a group of students from the Department of Earth and Atmospheric Sciences at the City College of New York studied these fluctuations. Electrical resistivity cross sections were obtained with a Syscal Kid Switch 24 resistivity meter during the course of a tidal cycle at three locations surrounding the westernmost inlet in the park. No change was seen over a tidal cycle at Site 1, possibly due to the effect of concrete erosion barriers which were located between the land and the water surrounding this site. Measurements at Site 2 revealed a small, regular change in the water table elevation of approximately 5 cm over the course of a tidal cycle. This site is inferred to rest on alluvial sediments deposited by a small creek. The cross sections taken at different times during a tidal cycle at Site 3 were the most interesting. They show a very heterogeneous subsurface, with water spurting between blocks of high resistivity materials during the rising portion of the cycle. A small sinkhole was observed on the surface of the ground directly above an obvious plume of water in the cross section. Park personnel confirmed that this sinkhole, like others scattered around this site, is natural and not due to recent construction activity. They also indicated that debris from the construction of the New York City subways may have been dumped in the area in the past. Our conclusion is that the tidal fluctuations at Site 3 are being channeled by solid blocks in the construction debris, and that the sinkholes currently
The effects of tidal range on saltmarsh morphology
Goodwin, Guillaume; Mudd, Simon
2017-04-01
Saltmarshes are highly productive coastal ecosystems that act simultaneously as flood barriers, carbon storage, pollutant filters and nurseries. As halophytic plants trap suspended sediment and decay in the settled strata, innervated platforms emerge from the neighbouring tidal flats, forming sub-vertical scarps on their eroding borders and sub-horizontal pioneer zones in areas of seasonal expansion. These evolutions are subject to two contrasting influences: stochastically generated waves erode scarps and scour tidal flats, whereas tidally-generated currents transport sediment to and from the marsh through the channel network. Hence, the relative power of waves and tidal currents strongly influences saltmarsh evolution, and regional variations in tidal range yield marshes of differing morphologies. We analyse several sheltered saltmarshes to determine how their morphology reflects variations in tidal forcing. Using tidal, topographic and spectral data, we implement an algorithm based on the open-source software LSDTopoTools to automatically identify features such as marsh platforms, tidal flats, erosion scarps, pioneer zones and tidal channels on local Digital Elevation Models. Normalised geometric properties are then computed and compared throughout the spectrum of tidal range, highlighting a notable effect on channel networks, platform geometry and wave exposure. We observe that micro-tidal marshes typically display jagged outlines and multiple islands along with wide, shallow channels. As tidal range increases, we note the progressive disappearance of marsh islands and linearization of scarps, both indicative of higher hydrodynamic stress, along with a structuration of channel networks and the increase of levee volume, suggesting higher sediment input on the platform. Future research will lead to observing and modelling the evolution of saltmarshes under various tidal forcing in order to assess their resilience to environmental change.
Source and dispersal of suspended sediment in the macro-tidal Gulf of Kachchh
Digital Repository Service at National Institute of Oceanography (India)
Ramaswamy, V.; Nath, B.N.; Vethamony, P.; Ilangovan, D.
and transport of carbon, minerals and pollutants to the oceans (Eisma, 1981; McKee, 2003). Macro-tidal areas are usually associated with high SSC because of higher energy conditions with sediments getting resuspended and transported depending on the harmonics... International 104, 69–86. Chandrasekharam, D., Mahoney, J.J., Sheth, H.C., Duncan, R.A., 1999. Elemental and Nd–Sr–Pb isotope geochemistry of flows and dikes from the Tapi rift, Deccan flood basalt province. India Journal of Volcanology and Geothermal Research...
Ship Creek bioassessment investigations
Energy Technology Data Exchange (ETDEWEB)
Cushing, C.E.; Mueller, R.P.; Murphy, M.T.
1995-06-01
Pacific Northwest Laboratory (PNL) was asked by Elmendorf Air Force Base (EAFB) personnel to conduct a series of collections of macroinvertebrates and sediments from Ship Creek to (1) establish baseline data on these populations for reference in evaluating possible impacts from Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) activities at two operable units, (2) compare current population indices with those found by previous investigations in Ship Creek, and (3) determine baseline levels of concentrations of any contaminants in the sediments associated with the macroinvertebrates. A specific suite of indices established by the US Environmental Protection Agency (EPA) was requested for the macroinvertebrate analyses; these follow the Rapid Bioassessment Protocol developed by Plafkin et al. (1989) and will be described. Sediment sample analyses included a Microtox bioassay and chemical analysis for contaminants of concern. These analyses included, volatile organic compounds, total gasoline and diesel hydrocarbons (EPA method 8015, CA modified), total organic carbon, and an inductive-coupled plasma/mass spectrometry (ICP/MS) metals scan. Appendix A reports on the sediment analyses. The Work Plan is attached as Appendix B.
The Patroon Creek Contamination Migration Investigation
International Nuclear Information System (INIS)
Dufek, K.; Zafran, A.; Moore, J.T.
2006-01-01
Shaw performed a Site Investigation (SI) for sediment within the Unnamed Tributary of the Patroon Creek, a section of the Patroon Creek, and the Three Mile Reservoir as part of the overall contract with the United States Army Corps of Engineers (USACE) to remediate the Colonie Formerly Utilized Sites Remedial Action Program (FUSRAP) Site. The Unnamed Tributary formerly flowed through the former Patroon Lake, which was located on the main site property and was used as a landfill for radiological and chemical wastes. The objective of the investigation was to determine the absence/presence of radioactive contamination within the three Areas of Concern (AOC). In order to accomplish this objective, Shaw assembled a team to produce a Technical Memorandum that provided an in-depth understanding of the environmental conditions related to the Patroon Creek. Upon completion and analysis of the Technical Memorandum, a Conceptual Site Model (CSM) was constructed and a Technical Planning Program (TPP) was held to develop a Sediment Investigation Work Plan and Sediment Investigation Sampling and Analysis Plan. A total of 32 sample locations were analyzed using on-site direct gamma scans with a Pancake Geiger-Mueller (PGM) instrument for screening purposes and samples were analyzed at on-site and off-site laboratories. The highest interval from each core scan was selected for on-site analysis utilizing a High Purity Germanium (HPGe) detector. Eight of these samples were sent off-site for gamma/alpha spectroscopy confirmation. The data collected during the SI indicated that the U-238 cleanup criterion was exceeded in sediment samples collected from two locations within the Unnamed Tributary but not in downstream sections of Patroon Creek or Three Mile Reservoir. Future actions for impacted sediment in the Unnamed Tributary will be further evaluated. Concentrations of U-238 and Th-232 in all other off-site sediment samples collected from the Unnamed Tributary, Patroon Creek, and
Stability of a sand spit due to dredging in an adjacent creek
Digital Repository Service at National Institute of Oceanography (India)
Patgaonkar, R.S.; Ilangovan, D.; Vethamony, P.; Babu, M.T.; Jayakumar, S.; Rajagopal, M.D.
, safety factor 1. Introduction The Jatadharmohan creek (hereinafter referred to as JMC) is a tidal creek oriented in the NE-SW direction (Fig. 1) and lies to the south of Paradip, along the east coast of India. This creek runs almost parallel... cor = 15 + (Nobs -15)/2, for Nobs > 15 b) Overburden correction: Ncor = Nobs x 350/ (? + 70) where, ? = overburden pressure The critical circular failure surface is the one for which factor of safety is the least. This is arrived...
Water quality of the Swatara Creek Basin, PA
McCarren, Edward F.; Wark, J.W.; George, J.R.
1964-01-01
The Swatara Creek of the Susquehanna River Basin is the farthest downstream sub-basin that drains acid water (pH of 4.5 or less) from anthracite coal mines. The Swatara Creek drainage area includes 567 square miles of parts of Schuylkill, Berks, Lebanon, and Dauphin Counties in Pennsylvania.To learn what environmental factors and dissolved constituents in water were influencing the quality of Swatara Creek, a reconnaissance of the basin was begun during the summer of 1958. Most of the surface streams and the wells adjacent to the principal tributaries of the Creek were sampled for chemical analysis. Effluents from aquifers underlying the basin were chemically analyzed because ground water is the basic source of supply to surface streams in the Swatara Creek basin. When there is little runoff during droughts, ground water has a dominating influence on the quality of surface water. Field tests showed that all ground water in the basin was non-acidic. However, several streams were acidic. Sources of acidity in these streams were traced to the overflow of impounded water in unworked coal mines.Acidic mine effluents and washings from coal breakers were detected downstream in Swatara Creek as far as Harper Tavern, although the pH at Harper Tavern infrequently went below 6.0. Suspended-sediment sampling at this location showed the mean daily concentration ranged from 2 to 500 ppm. The concentration of suspended sediment is influenced by runoff and land use, and at Harper Tavern it consisted of natural sediments and coal wastes. The average daily suspended-sediment discharge there during the period May 8 to September 30, 1959, was 109 tons per day, and the computed annual suspended-sediment load, 450 tons per square mile. Only moderate treatment would be required to restore the quality of Swatara Creek at Harper Tavern for many uses. Above Ravine, however, the quality of the Creek is generally acidic and, therefore, of limited usefulness to public supplies, industries and
Miller, Cherie V.; Chanat, Jeffrey G.; Bell, Joseph M.
2013-01-01
Concentrations and loading estimates for nutrients, suspended sediment, and E. coli bacteria were summarized for three water-quality monitoring stations on the Anacostia River in Maryland and one station on Rock Creek in Washington, D.C. Both streams are tributaries to the Potomac River in the Washington, D.C. metropolitan area and contribute to the Chesapeake Bay estuary. Two stations on the Anacostia River, Northeast Branch at Riverdale, Maryland and Northwest Branch near Hyattsville, Maryland, have been monitored for water quality during the study period from 2003 to 2011 and are located near the shift from nontidal to tidal conditions near Bladensburg, Maryland. A station on Paint Branch is nested above the station on the Northeast Branch Anacostia River, and has slightly less developed land cover than the Northeast and Northwest Branch stations. The Rock Creek station is located in Rock Creek Park, but the land cover in the watershed surrounding the park is urbanized. Stepwise log-linear regression models were developed to estimate the concentrations of suspended sediment, total nitrogen, total phosphorus, and E. coli bacteria from continuous field monitors. Turbidity was the strongest predictor variable for all water-quality parameters. For bacteria, water temperature improved the models enough to be included as a second predictor variable due to the strong dependence of stream metabolism on temperature. Coefficients of determination (R2) for the models were highest for log concentrations of suspended sediment (0.9) and total phosphorus (0.8 to 0.9), followed by E. coli bacteria (0.75 to 0.8), and total nitrogen (0.6). Water-quality data provided baselines for conditions prior to accelerated implementation of multiple stormwater controls in the watersheds. Counties are currently in the process of enhancing stormwater controls in both watersheds. Annual yields were estimated for suspended sediment, total nitrogen, total phosphorus, and E. coli bacteria using
Van Maren, D.S.; Winterwerp, J.C.; Vroom, J.
2015-01-01
Deepening of estuarine tidal channels often leads to tidal amplification and increasing fine sediment import. Increasing fine sediment import, in turn, may lower the hydraulic drag (due to a smoother muddy bed and/or sediment-induced damping of turbulence), and therefore, further strengthen tidal
Jaffe, B.E.; List, J.H.; Sallenger, A.H.
1997-01-01
Analysis of a series of historical bathymetric and shoreline surveys along the Louisiana coast west of the Mississippi River mouth detected a large area of deposition in water depths of 2.0–8.5 m offshore of a 9-km-wide tidal inlet, the Cat Island Pass/Wine Island Pass system. A 59.9 · 106 m3 sandy deposit formed from the 1930s–1980s, spanning 27 km in the alongshore direction, delineating the transport pathway for sediment bypassing offshore of the inlet on the shoreface. Bypassing connected the shorefaces of two barrier island systems, the Isles Dernieres and the Bayou Lafourche.The processes responsible for formation of this deposit are not well understood, but sediment-transport modeling suggests that sediment is transported primarily by wind-driven coastal currents during large storms and hurricanes. Deposition appears to be related to changes in shoreline orientation, closing of transport pathways into a large bay to the east and the presence of tidal inlets. This newly documented type of bypassing, an offshore bypassing of the inlet system, naturally nourished the immediate downdrift area, the eastern Isles Dernieres, where shoreface and shoreline erosion rates are about half of pre-bypassing rates. Erosion rates remained the same farther downdrift, where bypassing has not yet reached. As this offshore bypassing continues, the destruction of the Isles Dernieres will be slowed.
Krebs, Justin M.; McIvor, Carole C.; Bell, Susan S.
2014-01-01
To assess the potential influence of coastal development on estuarine-habitat quality, we characterized land use and the intensity of land development surrounding small tidal tributaries in Tampa Bay. Based on this characterization, we classified tributaries as undeveloped, industrial, urban, or man-made (i.e., mosquito-control ditches). Over one third (37 %) of the tributaries have been heavily developed based on landscape development intensity (LDI) index values >5.0, while fewer than one third (28 %) remain relatively undeveloped (LDI < 3.0). We then examined the nekton community from 11 tributaries in watersheds representing the four defined land-use classes. Whereas mean nekton density was independent of land use, species richness and nekton-community structure were significantly different between urban and non-urban (i.e., undeveloped, industrial, man-made) tributaries. In urban creeks, the community was species-poor and dominated by high densities of poeciliid fishes, Poecilia latipinna and Gambusia holbrooki, while typically dominant estuarine taxa including Menidia spp., Fundulus grandis, and Adinia xenica were in low abundance and palaemonid grass shrimp were nearly absent. Densities of economically important taxa in urban creeks were only half that observed in five of the six undeveloped or industrial creeks, but were similar to those observed in mosquito ditches suggesting that habitat quality in urban and mosquito-ditch tributaries is suboptimal compared to undeveloped tidal creeks. Furthermore, five of nine common taxa were rarely collected in urban creeks. Our results suggest that urban development in coastal areas has the potential to alter the quality of habitat for nekton in small tidal tributaries as reflected by variation in the nekton community.
Tidal River Management (TRM and Tidal Basin Management (TBM: A case study on Bangladesh
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Talchabhadel Rocky
2016-01-01
Full Text Available Bangladesh is the biggest delta of the world. Construction of numbers of polders is one of the flood resilient approach. But the presence of coastal polders de-linked the flood plain. The siltation in river causes riverbeds to become higher than the adjacent crop lands, and vast area under the polders became permanently water logged rendering large tract of land uncultivable. The current practice is temporarily de-poldering by cutting embankment. This is a natural water management process with very little human interventions but it needs strong participation and consensus with a great deal of sacrifice by the stakeholders for a specific period (3 to 5 years or even more[1]. An attempt has been made to study the phenomena of tidal basin management reviewing some secondary data and processes involved in successfully operated tidal basins of Bangladesh. And preliminary laboratory experiments are carried out to precisely look into the suspended sediment transport. With varying outflow discharge and sediment supply, the transport processes are investigated. 3D sediment transport model developed using openFOAM has good agreement with experimental result and can be used to better understand effectiveness of tidal basin management.
Remediation of muddy tidal flat sediments using hot air-dried crushed oyster shells.
Yamamoto, Tamiji; Kondo, Shunsuke; Kim, Kyung-Hoi; Asaoka, Satoshi; Yamamoto, Hironori; Tokuoka, Makoto; Hibino, Tadashi
2012-11-01
In order to prove that hot air-dried crushed oyster shells (HACOS) are effective in reducing hydrogen sulfide in muddy tidal flat sediments and increasing the biomass, field experiments were carried out. The concentration of hydrogen sulfide in the interstitial water, which was 16 mg SL(-1) before the application of HACOS, decreased sharply and maintained almost zero in the experimental sites (HACOS application sites) for one year, whereas it was remained at ca. 5 mg SL(-1) in the control sites. The number of macrobenthos individuals increased to 2-4.5 times higher than that in the control site. Using a simple numerical model, the effective periods for suppression of hydrogen sulfide were estimated to be 3.2-7.6 and 6.4-15.2 years for the experimental sites with 4 and 8 tons per 10 × 10 × 0.2m area, respectively. From these results, it is concluded that HACOS is an effective material to remediate muddy tidal flats. Copyright © 2012 Elsevier Ltd. All rights reserved.
Tidal Wetlands and Coastal Ocean Carbon Dynamics
Hopkinson, C.; Wang, S. R.; Forbrich, I.; Giblin, A. E.; Cai, W. J.
2017-12-01
Recent overviews of coastal ocean C dynamics have tidal wetlands in a prominent position: a local sink for atmospheric CO2, a local store of OC, and a source of DIC and OC for the adjacent estuary and nearshore ocean. Over the past decade there have been great strides made in quantifying and understanding these flows and linkages. GPP and R of the wetlands are not nearly as imbalanced as thought 30 yrs ago. Heterotrophy of adjacent estuarine waters is not solely due to the respiration of OC exported from the marsh, rather we see the marsh directly respiring into the water during tidal inundation and accumulated marsh DIC draining into tidal creeks. Organic carbon burial on the marsh is still a relatively minor flux, but it is large relative to marsh NEE. Using literature and unpublished data on marsh DIC export, we used examples from Sapelo Island GA USA and Plum Island MA USA to constrain estimates of NEP and potential OC export. P. There remain large uncertainties in quantifying C dynamics of coupled wetland - estuary systems. Gas exchange from the water to atmosphere is one of the largest uncertainties. Work at Sapelo suggests that upwards of 40% of all daily exchange occurs from water flooding the marsh, which is but a few hours a day. This estimate is based on the intercept value for gas exchange vs wind velocity. Another major uncertainty comes from converting between O2 based estimates of metabolism to C. At Sapelo we find PQ and RQ values diverging greatly from Redfield. Finally, C dynamics of the coastal ocean, especially the role of tidal wetlands is likely to change substantially in the future. Studies at Plum Island show a reversal of the 4000 yr process of marsh progradation with marshes eroding away at their edges because of inadequate sediment supply and rising sea level. The fate of eroded OC is questionable. Landward transgression with SLR is the only likely counter to continued wetland loss - but that's a complex social issue requiring new
Schile, Lisa M; Callaway, John C; Morris, James T; Stralberg, Diana; Parker, V Thomas; Kelly, Maggi
2014-01-01
Tidal marshes maintain elevation relative to sea level through accumulation of mineral and organic matter, yet this dynamic accumulation feedback mechanism has not been modeled widely in the context of accelerated sea-level rise. Uncertainties exist about tidal marsh resiliency to accelerated sea-level rise, reduced sediment supply, reduced plant productivity under increased inundation, and limited upland habitat for marsh migration. We examined marsh resiliency under these uncertainties using the Marsh Equilibrium Model, a mechanistic, elevation-based soil cohort model, using a rich data set of plant productivity and physical properties from sites across the estuarine salinity gradient. Four tidal marshes were chosen along this gradient: two islands and two with adjacent uplands. Varying century sea-level rise (52, 100, 165, 180 cm) and suspended sediment concentrations (100%, 50%, and 25% of current concentrations), we simulated marsh accretion across vegetated elevations for 100 years, applying the results to high spatial resolution digital elevation models to quantify potential changes in marsh distributions. At low rates of sea-level rise and mid-high sediment concentrations, all marshes maintained vegetated elevations indicative of mid/high marsh habitat. With century sea-level rise at 100 and 165 cm, marshes shifted to low marsh elevations; mid/high marsh elevations were found only in former uplands. At the highest century sea-level rise and lowest sediment concentrations, the island marshes became dominated by mudflat elevations. Under the same sediment concentrations, low salinity brackish marshes containing highly productive vegetation had slower elevation loss compared to more saline sites with lower productivity. A similar trend was documented when comparing against a marsh accretion model that did not model vegetation feedbacks. Elevation predictions using the Marsh Equilibrium Model highlight the importance of including vegetation responses to sea
Sedimentary Facies Mapping Based on Tidal Channel Network and Topographic Features
Ryu, J. H.; Lee, Y. K.; Kim, K.; Kim, B.
2015-12-01
Tidal flats on the west coast of Korea suffer intensive changes in their surface sedimentary facies as a result of the influence of natural and artificial changes. Spatial relationships between surface sedimentary facies distribution and benthic environments were estimated for the open-type Ganghwa tidal flat and semi closed-type Hwangdo tidal flat, Korea. In this study, we standardized the surface sedimentary facies and tidal channel index of the channel density, distance, thickness and order. To extract tidal channel information, we used remotely sensed data, such as those from the Korea Multi-Purpose Satellite (KOMPSAT)-2, KOMPSAT-3, and aerial photographs. Surface sedimentary facies maps were generated based on field data using an interpolation method.The tidal channels in each sediment facies had relatively constant meandering patterns, but the density and complexity were distinguishable. The second fractal dimension was 1.7-1.8 in the mud flat, about 1.4 in the mixed flat, and about 1.3 in the sand flat. The channel density was 0.03-0.06 m/m2 in the mud flat and less than 0.02 m/m2 in the mixed and sand flat areas of the two test areas. Low values of the tidal channel index, which indicated a simple pattern of tidal channel distribution, were identified at areas having low elevation and coarse-grained sediments. By contrast, high values of the tidal channel index, which indicated a dendritic pattern of tidal channel distribution, were identified at areas having high elevation and fine-grained sediments. Surface sediment classification based on remotely sensed data must circumspectly consider an effective critical grain size, water content, local topography, and intertidal structures.
Estimation of sediment inflows to Lake Tuscaloosa, Alabama, 2009-11
Lee, K.G.
2013-01-01
The U.S. Geological Survey, in cooperation with the City of Tuscaloosa, evaluated the concentrations, loads, and yields of suspended sediment in the tributaries to Lake Tuscaloosa in west-central Alabama, from October 1, 2008, to January 31, 2012. The collection and analysis of these data will facilitate the comparison with historical data, serve as a baseline for future sediment-collection efforts, and help to identify areas of concern. Lake Tuscaloosa, at the reservoir dam, receives runoff from a drainage area of 423 square miles (mi2). Basinwide in 2006, forested land was the primary land cover (68 percent). Comparison of historical imagery with the National Land Cover Database (2001 and 2006) indicated that the greatest temporal land-use change was timber harvest. The land cover in 2006 was indicative of this change, with shrub/scrub land (12 percent) being the secondary land use in the basin. Agricultural land use (10 percent) was represented predominantly by hay and pasture or grasslands. Urban land use was minimal, accounting for 4 percent of the entire basin. The remaining 6 percent of the basin has a land use of open water or wetlands. Storm and monthly suspended-sediment samples were collected from seven tributaries to Lake Tuscaloosa: North River, Turkey Creek, Binion Creek, Pole Bridge Creek, Tierce Creek, Carroll Creek, and Brush Creek. Suspended-sediment concentrations and streamflow measurements were statistically analyzed to estimate annual suspended-sediment loads and yields from each of these contributing watersheds. Estimated annual suspended-sediment yields in 2009 were 360, 540, and 840 tons per square mile (tons/mi2) at the North River, Turkey Creek, and Carroll Creek streamflow-gaging stations, respectively. Estimated annual suspended-sediment yields in 2010 were 120 and 86 tons/mi2 at the Binion Creek and Pole Bridge Creek streamflow-gaging stations, respectively. Estimated annual suspended-sediment yields in 2011 were 190 and 300 tons/mi2
Tidal River Elbe - a sediment budget for the grain size fraction of medium sand
Winterscheid, Axel
2016-04-01
Human interventions have a historic and ongoing impact on estuarine sediment budgets across many estuaries worldwide. An early inference was the construction of embankments resulting in a constant loss of intertidal flats. Additionally, settlement activities and large scale land use changes in the upstream catchment areas had also an effect on sediment inflow rates. Today, the navigation channels in estuaries have been deepened for larger and more efficient vessels to reach a well-developed infrastructure of harbors and industrial areas often located far inland. In the past few years and just within the North-East Atlantic, the total annual amount of dredged sediments dumped at sea varied from 80 to 130 million tons (OSPAR Commission). In most estuaries across Europe the resulting human impact on the sediment fluxes and morphodynamics is significant. A good understanding of estuarine processes is essential for determining useful and meaningful measures to mitigate negative effects and to improve the current situation. Maintenance dredging and its environmental effects are therefore in the focus of public attention. Against this background, it is the aim of the presentation to identify and therefore to separate the particular effect that maintenance dredging has on sediment fluxes and budgets in the estuarine environment. Case study is the Tidal River Elbe in Germany, and here we set the focus on the grain size fraction of medium sand. In the past, river engineering measures forced the natural dynamics to form a concentrated stream flow along a fixed channel, except at a number of locations where side channels still exist. In addition to that, the main channel was deepened several times. The last deepening was in 1999/2000. The most significant deepening, however, took place from 1957 to 1962. Until then, an erosion-stable layer of marine clay (in German called "Klei") formed a flat bottom along most sections of the main channel. After removal of this layer of
Miller, Todd S.; Karig, Daniel E.
2010-01-01
In 2002, the U.S. Geological Survey, in cooperation with the Tompkins County Planning Department began a series of studies of the stratified-drift aquifers in Tompkins County to provide geohydrologic data for planners to develop a strategy to manage and protect their water resources. This aquifer study in lower Sixmile Creek and Willseyville Creek trough is the second in a series of aquifer studies in Tompkins County. The study area is within the northern area of the Appalachian Plateau and extends about 9 miles from the boundary between Tompkins County and Tioga County in the south to just south of the City of Ithaca in the north. In lower Sixmile Creek and Willseyville Creek trough, confined sand and gravel aquifers comprise the major water-bearing units while less extensive unconfined units form minor aquifers. About 600 people who live in lower Sixmile Creek and Willseyville Creek trough rely on groundwater from the stratified-drift aquifer system. In addition, water is used by non-permanent residents such as staff at commercial facilities. The estimated total groundwater withdrawn for domestic use is about 45,000 gallons per day (gal/d) or 0.07 cubic foot per second (ft3/s) based on an average water use of 75 gal/d per person for self-supplied water systems in New York. Scouring of bedrock in the preglacial lower Sixmile Creek and Willseyville Creek valleys by glaciers and subglacial meltwaters truncated hillside spurs, formed U-shaped, transverse valley profiles, smoothed valley walls, and deepened the valleys by as much as 300 feet (ft), forming a continuous trough. The unconsolidated deposits in the study area consist mostly of glacial drift, both unstratified drift (till) and stratified drift (laminated lake, deltaic, and glaciofluvial sediments), as well as some post-glacial stratified sediments (lake-bottom sediments that were deposited in reservoirs, peat and muck that were deposited in wetlands, and alluvium deposited by streams). Multiple advances and
Tidal controls on river delta morphology
Hoitink, A. J. F.; Wang, Z. B.; Vermeulen, B.; Huismans, Y.; Kästner, K.
2017-09-01
River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and land reclamation emerge as key contemporary factors that exert an impact on delta morphology. Tides interacting with river discharge can play a crucial role in the morphodynamic development of deltas under pressure. Emerging insights into tidal controls on river delta morphology suggest that--despite the active morphodynamics in tidal channels and mouth bar regions--tidal motion acts to stabilize delta morphology at the landscape scale under the condition that sediment import during low flows largely balances sediment export during high flows. Distributary channels subject to tides show lower migration rates and are less easily flooded by the river because of opposing non-linear interactions between river discharge and the tide. These interactions lead to flow changes within channels, and a more uniform distribution of discharge across channels. Sediment depletion and rigorous human interventions in deltas, including storm surge defence works, disrupt the dynamic morphological equilibrium and can lead to erosion and severe scour at the channel bed, even decades after an intervention.
Modern sedimentary environments in a large tidal estuary, Delaware Bay
Knebel, H.J.
1989-01-01
Data from an extensive grid of sidescan-sonar records reveal the distribution of sedimentary environments in the large, tidally dominated Delaware Bay estuary. Bathymetric features of the estuary include large tidal channels under the relatively deep (> 10 m water depth) central part of the bay, linear sand shoals (2-8 m relief) that parallel the sides of the tidal channels, and broad, low-relief plains that form the shallow bay margins. The two sedimentary environments that were identified are characterized by either (1) bedload transport and/or erosion or (2) sediment reworking and/or deposition. Sand waves and sand ribbons, composed of medium to coarse sands, define sites of active bedload transport within the tidal channels and in gaps between the linear shoals. The sand waves have spacings that vary from 1 to 70 m, amplitudes of 2 m or less, and crestlines that are usually straight. The orientations of the sand waves and ribbons indicate that bottom sediment movement may be toward either the northwest or southeast along the trends of the tidal channels, although sand-wave asymmetry indicates that the net bottom transport is directed northwestward toward the head of the bay. Gravelly, coarse-grained sediments, which appear as strongly reflective patterns on the sonographs, are also present along the axes and flanks of the tidal channels. These coarse sediments are lag deposits that have developed primarily where older strata were eroded at the bay floor. Conversely, fine sands that compose the linear shoals and muddy sands that cover the shallow bay margins appear mainly on the sonographs either as smooth featureless beds that have uniform light to moderate shading or as mosaics of light and dark patches produced by variations in grain size. These acoustic and textural characteristics are the result of sediment deposition and reworking. Data from this study (1) support the hypothesis that bed configurations under deep tidal flows are functions of current
Energy Technology Data Exchange (ETDEWEB)
Revis, N.; Holdsworth, G.; Bingham, G.; King, A.; Elmore, J.
1989-04-01
This report presents results from a study conducted to determine the toxicity of Mercury in soils sediments samples. Mice were fed via diet, soils and sediment, from various locations along the East Fork Poplar creek. Tissue distribution of pollutants was determined at various intervals. The tissue level relative to toxicity was used to determine the effect of a complex matrix on the gastrointestinal absorption and tissue distribution of the pollutants (other pollutants included cadmium and selenium).
Hart, Rheannon M.
2014-01-01
Cypress Creek is located in central Arkansas and is the main tributary to Brewer Lake, which serves as the primary water supply for Conway, Arkansas, and the surrounding areas. A model of the Cypress Creek watershed was developed and calibrated in cooperation with Southwestern Energy Company using detailed precipitation, streamflow, and discrete suspended-sediment data collected from 2009 through 2012. These data were used with a Hydrologic Simulation Program—FORTRAN model to address different potential gas-extraction activities within the watershed.
Lagoon Sediment Dynamics: A Coupled Model to Study a Medium-Term Silting of Tidal Channels
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Marco Petti
2018-04-01
Full Text Available The silting of tidal channels is a natural process that affects several shallow lagoons and makes it difficult to navigate, requiring regular maintenance interventions. This phenomenon is the result of the complex non-linear interaction between tidal currents and wave motion. In this work, the morphodynamic evolution of the Marano and Grado lagoon is investigated by means of a two-dimensional horizontal (2DH morphological-hydrodynamic and a spectral coupled model. An innovative procedure to reproduce the overall bathymetric changes in the medium term and, in particular, the volumes deposited inside channels, is presented. An average year with a sequence of winds and tides acting over that time was reconstructed, carrying out cross correlation techniques and spectral analyses of measured data. The predicted morphological evolution matches the annual dredged volumes in the lagoon critical branches and shows the distribution of erosion and deposition of cohesive sediments according to spatially variable values of critical shear stress.
Organo chlorine pesticides (OCPs) contaminants in sediments from Karachi harbour, Pakistan
International Nuclear Information System (INIS)
Khan, N.; Khan, S.H.; Amjad, S.; Muller, J.; Nizamani, S.; Bhanger, M.I.
2010-01-01
Mangrove swamps, inter tidal mud flats and creeks of backwaters represent main feature of Karachi harbour area. Karachi harbour sediment is under continuous influence of untreated industrial effluents and domestic waste discharged into the Harbour area via Lyari River. Sediment samples from sixteen locations were collected to evaluate the levels of contamination of organo chlorine pesticides (OCPs) in Karachi harbour and adjoining areas. It has been observed that residual concentrations of various organo chlorine pesticides were considerably higher in the semi-enclosed area of the upper Harbour in the vicinity of the discharge point of Lyari River. The residue of DDT mainly its metabolites (DDE and DDD) were widely distributed and have been detected in most of the sediment samples in relatively higher concentrations as compared to other OCPs. The higher levels of the DDTs would attribute to low tidal flushing of the area. The high proportion of pp'-DDE in the most sediment sampled (41-95%) suggested old inputs of DDTs in the environment. Ratio of sigma DDT and DDT was in the range of 0.04 - 0.24 at all locations which also reflects that the discharges of DDT were negligible in the Harbour area. This may be due to the restrictions being implemented on the use of DDTs and Pakistan has also switched over to natural pest control or using safer formulas. The data obtained during the study showed that concentration levels of other pesticides such as HCHs, HCB and Cyclodienes in the sediment were generally lower than the threshold levels known to harm wildlife by OCPs. The results clearly indicate that elevated concentration of organo chlorine pesticides (OCPs) in the marine sediment of Karachi harbour and adjoining area was localized and much lower than the concentrations reported from neighbouring and regional countries which suggests/confirms that the present use of pesticide in Pakistan is environmentally safe. (author)
Use of an ADCP to compute suspended-sediment discharge in the tidal Hudson River, New York
Wall, Gary R.; Nystrom, Elizabeth A.; Litten, Simon
2006-01-01
Acoustic Doppler current profilers (ADCPs) can provide data needed for computation of suspended-sediment discharge in complex river systems, such as tidal rivers, in which conventional methods of collecting time-series data on suspended-sediment concentration (SSC) and water discharge are not feasible. Although ADCPs are not designed to measure SSC, ADCP data can be used as a surrogate under certain environmental conditions. However, the software for such computation is limited, and considerable post-processing is needed to correct and normalize ADCP data for this use. This report documents the sampling design and computational procedure used to calibrate ADCP measures of echo intensity to SSC and water velocity to discharge in the computation of suspended-sediment discharge at the study site on the Hudson River near Poughkeepsie, New York. The methods and procedures described may prove useful to others doing similar work in different locations; however, they are specific to this study site and may have limited applicability elsewhere.
Tidal pumping facilitates dissimilatory nitrate reduction in intertidal marshes
Zheng, Yanling; Hou, Lijun; Liu, Min; Liu, Zhanfei; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Yu, Chendi; Wang, Rong; Jiang, Xiaofen
2016-01-01
Intertidal marshes are alternately exposed and submerged due to periodic ebb and flood tides. The tidal cycle is important in controlling the biogeochemical processes of these ecosystems. Intertidal sediments are important hotspots of dissimilatory nitrate reduction and interacting nitrogen cycling microorganisms, but the effect of tides on dissimilatory nitrate reduction, including denitrification, anaerobic ammonium oxidation and dissimilatory nitrate reduction to ammonium, remains unexplored in these habitats. Here, we use isotope-tracing and molecular approaches simultaneously to show that both nitrate-reduction activities and associated functional bacterial abundances are enhanced at the sediment-tidal water interface and at the tide-induced groundwater fluctuating layer. This pattern suggests that tidal pumping may sustain dissimilatory nitrate reduction in intertidal zones. The tidal effect is supported further by nutrient profiles, fluctuations in nitrogen components over flood-ebb tidal cycles, and tidal simulation experiments. This study demonstrates the importance of tides in regulating the dynamics of dissimilatory nitrate-reducing pathways and thus provides new insights into the biogeochemical cycles of nitrogen and other elements in intertidal marshes. PMID:26883983
Andrews-Speed, C. P.
1986-07-01
The structurally defined Mporokoso Basin contains up to 5000 m of continental and marine clastic sediments and minor silicic volcanics which together form the Mporokoso Group. These rocks overlie unconformably a basement of silicic-intermediate igneous rocks and accumulated within the interval 1830-1130 Ma. This sedimentological study was restricted to the eastern end of the basin and was part of an assessment of the potential for palaeoplacer gold in the Mporokoso Group. At the base of the Mporokoso Group, the Mbala Formation consists of 1000-1500 m of purple sandstones and conglomerates deposited in a braided-stream system overlain by 500-1000 m of mature quartz arenites deposited in a tidal marine setting. A general coarsening-upward trend exists within the fluvial sediments. Sandy, distal braided-stream facies passes upwards into more proximal conglomeratic facies. In proximal sections, poorly sorted conglomerates form the top of the coarsening-up sequence which is 500-700 m thick. The overlying fluvial sediments fine upwards. The tidal marine sandstones at the top of the Mbala Formation resulted from reworking of fluvial sediments during a marine transgression. Well-exposed sections with fluvial conglomerates were studied in detail. Individual conglomerate bodies form sheets extending for hundreds of metres downstream and at least one hundred metres across stream, with little sign of deep scouring or channelling. They are generally matrix-supported. The whole fluvial sequence is characterised by a paucity of mud or silt. These conglomerates were deposited by large velocity, sheet flows of water which transported a bed-load of pebbles and sand. Most fine material settling out from suspension was eroded by the next flow. The great lateral and vertical extent and the uniformity of the fluvial sediments suggest that the sediments accumulated over an unconfined alluvial plain and that the tectonic evolution of the source area was relatively continuous and not
Classification of tidal inlets along the Central east coast of India
Digital Repository Service at National Institute of Oceanography (India)
Reddy, N.A.; Vikas, M.; Rao, S.; JayaKumar S.
) as long as the alongshore sediment bypasses the tidal inlet. Classification of coastal systems in a broader view is necessary for the management of tidal inlets. There are several methods to classify tidal inlets based on different perspectives namely geo...
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Ezekwe Clinton Ifeanyichukwu
2017-04-01
Full Text Available This study aimed at examining the impact of oil pollution from artisanal oil refineries on the Oturuba river ecosystem using active river bottom sediment. Specific objectives included to determine the level of hydrocarbons and trace metals (Pb, Cd, Zn, Cu, Ni, V and Mg in the sediments and to relate this with general ecosystem health. The study found elevated concentrations of both hydrocarbons and heavy metals in the range above most sediment quality guidelines exceeding the respective Threshold Effects Level and Probable Effects. Level guideline values and occurring at levels where impairment to biological communities is certain an d where toxicity levels can lead to negative impacts on benthic animals or infaunal communities. Heavy metal geochemical accumulation index and potential ecological risk analysis also returned anomalously high concentrations in the range of very highly polluted sediment environments with very high ecological risk indices, thereby ranking the Oturuba Creek as one of the most polluted coastal river systems in the world.
Bomer, J.; Wilson, C.; Hale, R. P.
2017-12-01
In the Ganges-Brahmaputra Delta (GBD) and other tide-dominated systems, periodic flooding of the land surface during the tidal cycle promotes sediment accretion and surface elevation gain over time. However, over the past several decades, anthropogenic modification of the GBD tidal deltaplain through embankment construction has precluded sediment delivery to catchment areas, leading to widespread channel siltation and subsidence in poldered landscapes. Amongst the current discussion on GBD sustainability, the relationship between tidal inundation period and resultant sedimentation in natural and embanked settings remains unclear. Moreover, an evaluation of how riparian sedimentology and stratigraphic architecture changes across the GBD tidal-fluvial spectrum is notably absent, despite its critical importance in assessing geomorphic change in human-impacted transitional environments. To provide local-scale, longitudinal trends of coupled landscape-channel dynamics, an array of surface elevation tables, groundwater piezometers, and sediment traps deployed in natural and embanked settings have been monitored seasonally over a time span of 4 years. This knowledge base will be extended across the GBD tidal-fluvial transition by collecting sediment cores from carefully selected point bars along the Gorai River. Sediments will be analyzed for lithologic, biostratigraphic, and geochemical properties to provide an integrated framework for discerning depositional zones and associated facies assemblages across this complex transitional environment. Preliminary comparisons of accretion and hydroperiod data suggest that inundation duration strongly governs mass accumulation on the intertidal platform, though other factors such as mass extraction from sediment source and vegetation density may play secondary roles.
Bedload transport in an inlet channel during a tidal cycle
DEFF Research Database (Denmark)
Ernstsen, V. B.; Becker, M.; Winter, C.
2007-01-01
Based on high-resolution swath bathymetry measurements at centimetre-scale precision conducted during a tidal cycle in a dune field in the Grådyb tidal inlet channel in the DanishWadden Sea, a simple tool to calculate bedload transport is presented. Bedload transport was related to simultaneous...... variations in grain-size composition of the mobilised sediment should be taken into account by sediment transport formulae....
Energy Technology Data Exchange (ETDEWEB)
Pinza, M.R.; Gardiner, W.W.; Barrows, E.S.; Borde, A.B.
1996-11-01
The objective of the Westchester Creek project was to evaluate proposed dredged material from this area to determine its suitability for unconfined ocean disposal at the Mud Dump Site. Westchester Creek was one of five waterways that the US Army Corps of Engineers- New York District (USACE-NYD) requested the Battelle/Marine Sciences Laboratory (MSL) to sample and evaluate for dredging and disposal in May 1995. The evaluation of proposed dredged material from the Westchester Creek project area consisted of bulk sediment chemical analyses, chemical analyses of dredging site water and elutriate, benthic acute and water-column toxicity tests, and bioaccumulation studies. Thirteen individual sediment core samples were collected from this area and analyzed for grain size, moisture content, and total organic carbon (TOC). One composite sediment sample representing the Westchester Creek area to be dredged, was analyzed for bulk density, specific gravity, metals, chlorinated pesticides, polychlorinated biphenyl (PCB) congeners, polynuclear aromatic hydrocarbons (PAHs), and 1,4-dichlorobenzene. Dredging site water and elutriate water, which is prepared from the suspended- particulate phase (SPP) of the Westchester Creek sediment composite, was analyzed for metals, pesticides, and PCBS.
Flow and sediment transport in an Indonesian tidal network
Buschman, F.A.
2011-01-01
The Berau river, situated in east Kalimantan (Indonesia), drains a relatively small catchment area and splits into several interconnected tidal channels. This tidal network connects to the sea. The sea is host to extremely diverse coral reef communities. Also the land side of the region is
A review of occurrence of pharmaceuticals in sediments
African Journals Online (AJOL)
PaxGroup
the biosorption process was evaluated. Williams and Kookana (2010) investigated isotophic exchangeability as a measure of carbamazepine, an antiepileptic pharmaceutical compound, in river sediment. The sediment used for the batch sorption experiments was collected from Mackreath Creek, Scott Creek. Conservation ...
Scasso, Roberto A.; Cuitiño, José I.
2017-08-01
This special issue of Geo-Marine Letters presents selected contributions from the 9th International Conference on Tidal Sedimentology held on 17-19 November 2015 in Puerto Madryn, Chubut Province, Patagonia, Argentina. The guest editors are the conference organizers Roberto A. Scasso and José I. Cuitiño. Gerardo M. Perillo was the head of the Scientific Committee. The conferences on tidal sedimentology have been traditionally held every 4 years. However, only 3 years separated the last conference held in Caen (France, 2012) from this conference. Increasing numbers of contributions and the growing interest in tidal sedimentation have been the reasons for shortening the inter-conference period. The 2015 conference served as a discussion forum focusing on advances in modern and ancient tidal sedimentation at different locations worldwide. The papers presented in this Special Issue provide a selective view of the latest research results, the main topics dealing with tidal hydrodynamics and sediment transport, tidal coastal morphodynamics, modern and ancient tidal sedimentation, geotechnical processes in tidal environments, and tidal basins, facies and reservoirs.
Organic geochemistry in Pennsylvanian tidally influenced sediments from SW Indiana
Mastalerz, Maria; Kvale, E.P.; Stankiewicz, B.A.; Portle, K.
1999-01-01
Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana have been analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter (OM) preserved in an environment of daily interactions between marine and fresh waters. The concentration of organic matter (TOC) ranges from traces to 6.9% and sulfur rarely exceeds 0.1% in individual laminae. Angular vitrinite is the major organic matter type, accounting for 50-90% of total OM. The C/S ratio decreases as the verfical distance from the underlying coal increases. A decreasing C/S ratio coupled with decreases in Pr/Ph, Pr/n-C17, Ph/n-C18 ratios and a shift of carbon isotopic composition towards less negative values suggest an increase in salinity from freshwater in the mudflat tidal rhythmite facies close to the coal to brackish/marine in the sandflat tidal rhythmite facies further above from the coal. Within an interval spanning one year of deposition, TOC and S values show monthly variability. On a daily scale, TOC and S oscillations are still detectable but they are of lower magnitude than on a monthly scale. These small-scale variations are believed to reflect oscillations in water salinity related to tidal cycles.Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana have been analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter (OM) preserved in an environment of daily interactions between marine and fresh waters. The concentration of organic matter
Directory of Open Access Journals (Sweden)
B. Gribsholt
2007-01-01
Full Text Available An intact tidal freshwater marsh system (3477 m2 was labelled by adding 15N-ammonium as a tracer to the flood water inundating the ecosystem. The appearance and retention of 15N-label in different marsh components (leaves, roots, sediment, leaf litter and invertebrate fauna was followed over 15 days. This allowed us to elucidate the direct assimilation and dependence on creek-water nitrogen on a relatively short term and provided an unbiased assessment of the relative importance of the various compartments within the ecosystem. Two separate experiments were conducted, one in spring/early summer (May 2002 when plants were young and building up biomass; the other in late summer (September 2003 when macrophytes were in a flowering or early senescent state. Nitrogen assimilation rate (per hour inundated was >3 times faster in May compared to September. On both occasions, however, the results clearly revealed that the less conspicuous compartments such as leaf litter and ruderal vegetations are more important in nitrogen uptake and retention than the prominent reed (Phragmites australis meadows. Moreover, short-term nitrogen retention in these nutrient rich marshes occurs mainly via microbial pathways associated with the litter and sediment. Rather than direct uptake by macrophytes, it is the large reactive surface area provided by the tidal freshwater marsh vegetation that is most crucial for nitrogen transformation, assimilation and short term retention in nutrient rich tidal freshwater marshes. Our results clearly revealed the dominant role of microbes in initial nitrogen retention in marsh ecosystems.
Study of the sediment contamination levels in a mangrove swamp polluted by a marine oil spill
Energy Technology Data Exchange (ETDEWEB)
Wong, T.W.Y.; Ke, L.; Wong, Y.S.; Tam, N.F.Y. [City University of Hong Kong, Hong Kong SAR (China)
2002-07-01
The pattern of oil retention in mangrove sediments was studied in an effort to determine the temporal changes of petroleum hydrocarbon concentrations and composition several months after oil spills occur. Mangroves are inter-tidal wetlands in tropical and subtropical coastlines. Due to the anoxic and water logging characteristics of mangrove sediments, oil residues linger much longer in these wetlands compared to other coastal habitats. In November 2000, an accidental oil spill occurred in the Pearl River Estuary in which approximately 230,000 litres of crude oil was leaked from an oil tanker. The spilled oil migrated to the YiO, a typical mangrove swamp in Hong Kong Special Administrative Region. The degree of oil contamination in the sediments depended on the sediment texture and topography of the mangrove. The total petroleum hydrocarbon (TPH) concentration of the sediments in the most affected area near a freshwater creek flowing into the sea was 130 times higher than normal, one month after the accident. The mean TPH concentration was 2862 ug/g of dry sediment while the mean carbon preference index was 1.22 compared to the background value of 3.97. The temporal changes of the petroleum hydrocarbon level in 5 defined areas were examined for 7 months after the spill. The most polluted area next to the creek was determined to have very high TPH levels in the muddy sediments even 7 months after the spill. Oil residues infiltrated as deep as 20 cm into the sediments, making it more difficult to degrade than surface pollution and posing long-term adverse effects on trees in the area. It was determined that with growing industrialization and increasing demands for fuel and energy supply, mangroves in South China should be ranked as top priority for protection from oil spills. 19 refs., 6 tabs., 6 figs.
Study of the sediment contamination levels in a mangrove swamp polluted by a marine oil spill
International Nuclear Information System (INIS)
Wong, T.W.Y.; Ke, L.; Wong, Y.S.; Tam, N.F.Y.
2002-01-01
The pattern of oil retention in mangrove sediments was studied in an effort to determine the temporal changes of petroleum hydrocarbon concentrations and composition several months after oil spills occur. Mangroves are inter-tidal wetlands in tropical and subtropical coastlines. Due to the anoxic and water logging characteristics of mangrove sediments, oil residues linger much longer in these wetlands compared to other coastal habitats. In November 2000, an accidental oil spill occurred in the Pearl River Estuary in which approximately 230,000 litres of crude oil was leaked from an oil tanker. The spilled oil migrated to the YiO, a typical mangrove swamp in Hong Kong Special Administrative Region. The degree of oil contamination in the sediments depended on the sediment texture and topography of the mangrove. The total petroleum hydrocarbon (TPH) concentration of the sediments in the most affected area near a freshwater creek flowing into the sea was 130 times higher than normal, one month after the accident. The mean TPH concentration was 2862 ug/g of dry sediment while the mean carbon preference index was 1.22 compared to the background value of 3.97. The temporal changes of the petroleum hydrocarbon level in 5 defined areas were examined for 7 months after the spill. The most polluted area next to the creek was determined to have very high TPH levels in the muddy sediments even 7 months after the spill. Oil residues infiltrated as deep as 20 cm into the sediments, making it more difficult to degrade than surface pollution and posing long-term adverse effects on trees in the area. It was determined that with growing industrialization and increasing demands for fuel and energy supply, mangroves in South China should be ranked as top priority for protection from oil spills. 19 refs., 6 tabs., 6 figs
Braun, Christopher L.; Wilson, Jennifer T.
2010-01-01
Meandering Road Creek is an intermittent stream and tributary to Lake Worth, a reservoir on the West Fork Trinity River on the western edge of Fort Worth, Texas. U.S. Air Force Plant 4 (AFP4) is on the eastern shore of Woods Inlet, an arm of Lake Worth. Meandering Road Creek gains inflow from several stormwater outfalls as it flows across AFP4. Several studies have characterized polychlorinated biphenyls (PCBs) in the water and sediments of Lake Worth and Meandering Road Creek; sources of PCBs are believed to originate primarily from AFP4. Two previous U.S. Geological Survey (USGS) reports documented elevated PCB concentrations in surficial sediment samples from Woods Inlet relative to concentrations in surficial sediment samples from other parts of Lake Worth. The second of these two previous reports also identified some of the sources of PCBs to Lake Worth. These reports were followed by a third USGS report that documented the extent of PCB contamination in Meandering Road Creek and Woods Inlet and identified runoff from outfalls 4 and 5 at AFP4 as prominent sources of these PCBs. This report describes the results of a fourth study by the USGS, in cooperation with the Lockheed Martin Corporation, to investigate PCBs in suspended-sediment samples in storm runoff from outfalls 4 and 5 at AFP4 following the implementation of engineering controls designed to potentially alleviate PCB contamination in the drainage areas of these outfalls. Suspended-sediment samples collected from outfalls 4 and 5 during storms on March 2 and November 10, 2008, were analyzed for selected PCBs. Sums of concentrations of 18 reported PCB congeners (Sigma PCBc) in suspended-sediment samples collected before and after implementation of engineering controls are compared. At both outfalls, the Sigma PCBc before engineering controls was higher than the Sigma PCBc after engineering controls. The Sigma PCBc in suspended-sediment samples collected at AFP4 before and after implementation of
Physical processes affecting turbidity in a tidal marsh across a range of time scales
Arnold, W.; Poindexter, C.
2016-12-01
The direction of net suspended sediment flux, whether into or out of a tidal marsh, can determine whether a marsh is aggrading or eroding. Measuring net suspended sediment fluxes or attributing trends in these fluxes to a particular physical processes is challenging because suspended sediment concentrations are highly variable in time. We used singular spectrum analysis for time series with missing data (SSAM) to observe the relative effects on turbidity of physical processes occurring on different time scales at the Rush Ranch Open Space Preserve. This Preserve covers the largest contiguous area of full-tidal marsh remaining within Suisun Bay, the eastern most subembayment of San Francisco Bay. A long-term monitoring station at First Mallard Slough within the Preserve measures turbidity. Our analysis of of this turbidity record isolated the contribution to total variance from different tides and from annual cycles of San Francisco Bay freshwater inflow, sediment deposition and wind-driven sediment resuspension. Surprisingly, the contribution from diurnal and semidiurnal tidal constituents (30%) was smaller than the contribution from annual cycles of freshwater inflow, sediment deposition and resuspension (38%). This result contrasts with the original implementation of SSAM to suspended sediment concentration, which was conducted in the central San Francisco Bay. This previous work indicated a significant yet smaller contribution (13%) to total suspended sediment concentration variance from annual cycles (Schoellhamer, D. H., 2002, Continental Shelf Research., 22, 1857-1866). The reason for the contrast relates in part to the location of the First Mallard Slough more than 10 km along the tidal channel network from Suisun Bay. At this location, the lowest frequency variation in suspended sediment is accentuated. Annual peaks in turbidity at First Mallard depend not only on spring and summer wind-driven resuspension of sediment in San Pablo Bay but also its co
A life-cycle model for wave-dominated tidal inlets along passive margin coasts of North America
Seminack, Christopher T.; McBride, Randolph A.
2018-03-01
A regional overview of 107 wave-dominated tidal inlets along the U.S. Atlantic coast, U.S. Gulf of Mexico coast, and Canadian Gulf of St. Lawrence coast yielded a generalized wave-dominated tidal inlet life-cycle model that recognized the rotational nature of tidal inlets. Tidal inlets are influenced by concurrently acting processes transpiring over two timescales: short-term, event-driven processes and long-term, evolutionary processes. Wave-dominated tidal inlets are classified into three rotational categories based on net longshore sediment transport direction and rotation direction along the landward (back-barrier) portion of the inlet channel: downdrift channel rotation, updrift channel rotation, or little-to-no channel rotation. Lateral shifting of the flood-tidal delta depocenter in response to available estuarine accommodation space appears to control inlet channel rotation. Flood-tidal delta deposits fill accommodation space locally within the estuary (i.e., creating bathymetric highs), causing the tidal-inlet channel to rotate. External influences, such as fluvial discharge, pre-existing back-barrier channels, and impeding salt marsh will also influence inlet-channel rotation. Storm events may rejuvenate the tidal inlet by scouring sediment within the flood-tidal delta, increasing local accommodation space. Wave-dominated tidal inlets are generally unstable and tend to open, concurrently migrate laterally and rotate, infill, and close. Channel rotation is a primary reason for wave-dominated tidal inlet closure. During rotation, the inlet channel lengthens and hydraulic efficiency decreases, thus causing tidal prism to decrease. Tidal prism, estuarine accommodation space, and sediment supply to the flood-tidal delta are the primary variables responsible for tidal inlet rotation. Stability of wave-dominated tidal inlets is further explained by: stability (S) = tidal prism (Ω) + estuarine accommodation space (V) - volume of annual sediment supply (Mt
Cyclic Sediment Trading Between Channel and River Bed Sediments
Haddadchi, A.
2015-12-01
Much of the previous work on sediment tracing has focused on determining either the initial sources of the sediment (soils derive from a particular rock type) or the erosion processes generating the sediment. However, alluvial stores can be both a source and sink for sediment transported by streams. Here geochemical and fallout radionuclide tracing of river-bed and alluvial sediments are used to determine the role of secondary sources, sediment stores, as potential sources of sediment leaving Emu Creek catchment, southeastern Queensland, Australia. Activity concentrations of 137Cs on the river sediments are consistent with channel erosion being the dominant source at all sites sampled along the river. To characterise the deposition and remobilisation cycles in the catchment, a novel geochemical tracing approach was used. Successive pockets of alluvium were treated as discrete sink terms within geochemical mixing models and their source contributions compared with those of river bed sediments collected adjacent to each alluvial pocket. Three different size fractions were examined; silts and clays (banks indicates a high degree of 'trading' between the fluvial space and the alluvial space. Hence, management works aimed at primarily reducing the supply of sediments to the outlet of Emu Creek should focus on rehabilitation of channel banks in the lower catchment.
International Nuclear Information System (INIS)
Bernardi, S.; Costa, F.; Vazzoler, S.; Zonta, R.
1988-01-01
Data are from the two series of surface sediment sampling in an interface area between the Venice Lagoon and the mainland. The distribution of heavy metals gives a correlation with polluted sourcesites-identified in the channel systems with a highly polluted input-and allows us to identify the localities of accumulation. Restricted to the estuary of the river tributary transporting a high concentration of pollutants into a tidal marsh area of the lagoon, the study shows the effect of the fresh water forcing to distribute heavy metals on surface sediments. Within the scope of this preliminary investigation, indications from sampling identify a sector of the 'palude of Cona' in this estuary, which is highly suitable for detailed studies on precesses affecting heavy-metal distributions in bottom surface sediments of shallow-water areas
A. Mrutu; G. B. Luilo
2013-01-01
Mangrove wetlands are important biological systems that usually filter out organic and inorganic contaminants from the wastewaters before entering the ocean. Our previous work showed that sediments of the Msimbazi Creek wetland are contaminated with heavy metals and the amounts decreased with increasing depth. However, the hidden relationships between the heavy metals and clay particles were not fully understood based on the numerical data. Therefore this work used the data from literature an...
A Summary of the San Francisco Tidal Wetlands Restoration Series
Directory of Open Access Journals (Sweden)
Larry R. Brown
2003-10-01
Full Text Available The four topical articles of the Tidal Wetlands Restoration Series summarized and synthesized much of what is known about tidal wetlands and tidal wetland restoration in the San Francisco Estuary (hereafter “Estuary”. Despite a substantial amount of available information, major uncertainties remain. A major uncertainty with regard to fishes is the net benefit of restored tidal wetlands relative to other habitats for native fishes in different regions of the Estuary given the presence of numerous invasive alien species. With regard to organic carbon, a major uncertainty is the net benefit of land use change given uncertainty about the quantity and quality of different forms of organic carbon resulting from different land uses. A major challenge is determining the flux of organic carbon from open systems like tidal wetlands. Converting present land uses to tidal wetlands will almost certainly result in increased methylation of mercury at the local scale with associated accumulation of mercury within local food webs. However, it is unclear if such local accumulation is of concern for fish, wildlife or humans at the local scale or if cumulative effects at the regional scale will emerge. Based on available information it is expected that restored tidal wetlands will remain stable once constructed; however, there is uncertainty associated with the available data regarding the balance of sediment accretion, sea-level rise, and sediment erosion. There is also uncertainty regarding the cumulative effect of many tidal restoration projects on sediment supply. The conclusions of the articles highlight the need to adopt a regional and multidisciplinary approach to tidal wetland restoration in the Estuary. The Science Program of the CALFED effort provides an appropriate venue for addressing these issues.
Water quality monitoring report for the White Oak Creek Embayment
International Nuclear Information System (INIS)
Ford, C.J.; Wefer, M.T.
1993-01-01
Water quality monitoring activities that focused on the detection of resuspended sediments in the Clinch River were conducted in conjunction with the White Oak Creek Embayment (WOCE) time-critical Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) removal action to construct a sediment-retention structure at the mouth of White Oak Creek (WOC). Samples were collected by use of a 24-h composite sampler and through real-time water grab sampling of sediment plumes generated by the construction activities. Sampling stations were established both at the WOC mouth, immediately adjacent to the construction site, and at K-1513, the Oak Ridge K-25 Site drinking water intake approximately 9.6 km downstream in the Clinch River. Results are described
International Nuclear Information System (INIS)
Gaspare, Lydia; Machiwa, John F.; Mdachi, S.J.M.; Streck, Georg; Brack, Werner
2009-01-01
Surface sediment and oyster samples from the inter-tidal areas of Dar es Salaam were analyzed for 23 polycyclic aromatic hydrocarbons (PAHs) including the 16 compounds prioritized by US-EPA using GC/MS. The total concentration of PAHs in the sediment ranged from 78 to 25,000 ng/g dry weight, while oyster concentrations ranged from 170 to 650 ng/g dry weight. Hazards due to sediment contamination were assessed using Equilibrium Partitioning Sediment Benchmarks and Threshold Effect Levels. Diagnostic indices and principle component analysis were used to identify possible sources. Interestingly, no correlation between sediment and oyster concentrations at the same sites was found. This is supported by completely different contamination patterns, suggesting different sources for both matrices. Hazard assessment revealed possible effects at six out of eight sites on the benthic communities and oyster populations. The contribution of PAH intake via oyster consumption to carcinogenic risks in humans seems to be low. - PAH contamination may pose hazards to benthos but limited risks to humans
Energy Technology Data Exchange (ETDEWEB)
Gaspare, Lydia; Machiwa, John F. [Department of Aquatic Environment and Conservation, University of Dar es Salaam, P.O. Box 60091, Dar es Salaam (Tanzania, United Republic of); Mdachi, S.J.M. [Department of Chemistry, University of Dar es Salaam, P.O. Box 35062, Dar es Salaam (Tanzania, United Republic of); Streck, Georg [UFZ Helmholtz Centre for Environmental Research Leipzig-Halle, Department of Effect-Directed Analysis, Permoserstrasse 15, 04318 Leipzig (Germany); Brack, Werner [UFZ Helmholtz Centre for Environmental Research Leipzig-Halle, Department of Effect-Directed Analysis, Permoserstrasse 15, 04318 Leipzig (Germany)], E-mail: werner.brack@ufz.de
2009-01-15
Surface sediment and oyster samples from the inter-tidal areas of Dar es Salaam were analyzed for 23 polycyclic aromatic hydrocarbons (PAHs) including the 16 compounds prioritized by US-EPA using GC/MS. The total concentration of PAHs in the sediment ranged from 78 to 25,000 ng/g dry weight, while oyster concentrations ranged from 170 to 650 ng/g dry weight. Hazards due to sediment contamination were assessed using Equilibrium Partitioning Sediment Benchmarks and Threshold Effect Levels. Diagnostic indices and principle component analysis were used to identify possible sources. Interestingly, no correlation between sediment and oyster concentrations at the same sites was found. This is supported by completely different contamination patterns, suggesting different sources for both matrices. Hazard assessment revealed possible effects at six out of eight sites on the benthic communities and oyster populations. The contribution of PAH intake via oyster consumption to carcinogenic risks in humans seems to be low. - PAH contamination may pose hazards to benthos but limited risks to humans.
Hanegan, K.; Georgiou, I. Y.; FitzGerald, D.
2016-02-01
Along barrier island chains, tidal exchange between the backbarrier and the coastal ocean supports unique saltwater and brackish ecosystems and is responsible for exporting sediment and nutrients to the surrounding coast. Tidal prism, basement controls, and wave and tidal energy dictate the size and number of tidal inlets and the volume of sand sequestered in ebb-tidal deltas. The inlet tidal prism is a function of bay area, tidal range, and secondary controls, including flow inertia, basinal hypsometry, and frictional factors. Sea- level rise (SLR) is threatening coastal environments, causing mainland flooding, changes in sediment supply, and conversion of wetlands and tidal flats to open water. These factors are impacting basinal hypsometry and increasing open water area, resulting in enlarging tidal prisms, increased dimensions of tidal inlets and ebb-tidal deltas, and erosion along adjacent barrier shorelines. Although the effects of SLR on coastal morphology are difficult to study by field observations alone, physics-based numerical models provide a sophisticated means of analyzing coastal processes over decadal time-scales and linking process causation to long term development. Here, we use a numerical model that includes relevant features in the barrier/tidal basin system, linking back-barrier marsh degradation, inlet expansion, and ebb-delta growth to barrier erosion through long-term hydrodynamic and morphology simulations. Sediment exchange and process interactions are investigated using an idealized domain resembling backbarrier basins of mixed energy coasts so that the sensitivity to varying SLR rates, interior marsh loss, sediment supply, and hydrodynamic controls can be more easily analyzed. Model runs explore these processes over geologic time scales, demonstrating the vulnerability of backbarrier systems to projected SLR and marsh loss. Results demonstrate the links between changing basin morphology and shoreface sedimentation patterns that initiate
Can barrier islands survive sea level rise? Tidal inlets versus storm overwash
Nienhuis, J.; Lorenzo-Trueba, J.
2017-12-01
Barrier island response to sea level rise depends on their ability to transgress and move sediment to the back barrier, either through flood-tidal delta deposition or via storm overwash. Our understanding of these processes over decadal to centennial timescales, however, is limited and poorly constrained. We have developed a new barrier inlet environment (BRIE) model to better understand the interplay between tidal dynamics, overwash fluxes, and sea-level rise on barrier evolution. The BRIE model combines existing overwash and shoreface formulations [Lorenzo-Trueba and Ashton, 2014] with alongshore sediment transport, inlet stability [Escoffier, 1940], inlet migration and flood-tidal delta deposition [Nienhuis and Ashton, 2016]. Within BRIE, inlets can open, close, migrate, merge with other inlets, and build flood-tidal delta deposits. The model accounts for feedbacks between overwash and inlets through their mutual dependence on barrier geometry. Model results suggest that when flood-tidal delta deposition is sufficiently large, barriers require less storm overwash to transgress and aggrade during sea level rise. In particular in micro-tidal environments with asymmetric wave climates and high alongshore sediment transport, tidal inlets are effective in depositing flood-tidal deltas and constitute the majority of the transgressive sediment flux. Additionally, we show that artificial inlet stabilization (via jetty construction or maintenance dredging) can make barrier islands more vulnerable to sea level rise. Escoffier, F. F. (1940), The Stability of Tidal Inlets, Shore and Beach, 8(4), 114-115. Lorenzo-Trueba, J., and A. D. Ashton (2014), Rollover, drowning, and discontinuous retreat: Distinct modes of barrier response to sea-level rise arising from a simple morphodynamic model, J. Geophys. Res. Earth Surf., 119(4), 779-801, doi:10.1002/2013JF002941. Nienhuis, J. H., and A. D. Ashton (2016), Mechanics and rates of tidal inlet migration: Modeling and application to
Pataha Creek Model Watershed : January 2000-December 2002 Habitat Conservation Projects.
Energy Technology Data Exchange (ETDEWEB)
Bartels, Duane G.
2003-04-01
The projects outlined in detail on the attached project reports were implemented from calendar year 2000 through 2002 in the Pataha Creek Watershed. The Pataha Creek Watershed was selected in 1993, along with the Tucannon and Asotin Creeks, as model watersheds by NPPC. In previous years, demonstration sites using riparian fencing, off site watering facilities, tree and shrub plantings and upland conservation practices were used for information and education and were the main focus of the implementation phase of the watershed plan. These practices were the main focus of the watershed plan to reduce the majority of the sediment entering the stream. Prior to 2000, several bank stabilization projects were installed but the installation costs became prohibitive and these types of projects were reduced in numbers over the following years. The years 2000 through 2002 were years where a focused effort was made to work on the upland conservation practices to reduce the sedimentation into Pataha Creek. Over 95% of the sediment entering the stream can be tied directly to the upland and riparian areas of the watershed. The Pataha Creek has steelhead in the upper reaches and native and planted rainbow trout in the mid to upper portion. Suckers, pikeminow and shiners inhabit the lower portion because of the higher water temperatures and lack of vegetation. The improvement of riparian habitat will improve habitat for the desired fish species. The lower portion of the Pataha Creek could eventually develop into spawning and rearing habitat for chinook salmon if some migration barriers are removed and habitat is restored. The upland projects completed during 2000 through 2002 were practices that reduce erosion from the cropland. Three-year continuous no-till projects were finishing up and the monitoring of this particular practice is ongoing. Its direct impact on soil erosion along with the economical aspects is being studied. Other practices such as terrace, waterway, sediment
International Nuclear Information System (INIS)
Tye, A.M.; Rawlins, B.G.; Rushton, J.C.; Price, R.
2016-01-01
The release of Phosphorus (P) from river sediments has been identified as a contributing factor to waters failing the criteria for ‘Good Ecological Status’ under the EU Water Framework Directive (WFD). To identify the contribution of sediment-P to river systems, an understanding of the factors that influence its distribution within the entire non-tidal system is required. Thus the aims of this work were to examine the (i) total (P_T_o_t_a_l) and labile (P_L_a_b_i_l_e) concentrations in sediment, (ii) the sequestration processes and (iii) the interactions between sediment P and the river water in the six non-tidal water bodies of the River Nene, U.K. Collection of sediments followed a long period of flooding and high stream flow. In each water body, five cores were extracted and homogenised for analysis with an additional core being taken and sampled by depth increments. Comparing the distribution of sediment particle size and P_T_o_t_a_l data with soil catchment geochemical survey data, large increases in P_T_o_t_a_l were identified in sediments from water body 4–6, where median concentrations of P_T_o_t_a_l in the sediment (3603 mg kg"−"1) were up to double those of the catchment soils. A large proportion of this increase may be related to in-stream sorption of P, particularly from sewage treatment facilities where the catchment becomes more urbanised after water body 3. A linear correlation (r = 0.8) between soluble reactive phosphate (SRP) and Boron in the sampled river waters was found suggesting increased STW input in water bodies 4–6. P_L_a_b_i_l_e concentrations in homogenised cores were up to 100 mg kg"−"1 PO_4–P (generally < 2% of P_T_o_t_a_l) and showed a general increase with distance from the headwaters. A general increase in Equilibrium Phosphate Concentrations (EPC_0) from an average of 0.9–∼1.7 μm L"−"1 was found between water bodies 1–3 and 4–6. Fixation within oxalate extractable phases (Al, Fe and Mn) accounted
Meynecke, Jan-Olaf; Poole, Geoffrey C.; Werry, Jonathan; Lee, Shing Yip
2008-08-01
We assessed movement patterns in relation to habitat availability (reflected by the extent of tidal flooding) for several commercially and recreationally important species in and out of a small mangrove creek within the subtropical Burrum River estuary (25°10'S 152°37'E) in Queensland, Australia. Movement patterns of Acanthopagrus australis, Pomadasys kaakan, Lutjanus russelli and Mugil cephalus were examined between December 2006 and April 2007 using a stationary passive integrated transponder (PIT) system adapted for saline environments (30-38 ppt) and underwater digital video cameras (DVCs). This is the second known application of a stationary PIT tag system to studying fish movement in estuarine environments. The transponder system was set in place for 104 days and recorded >5000 detections. Overall 'recapture' rate of tagged fish by the transponder system was >40%. We used PIT tags implanted in a total of 75 fish from a tidal creek connected to the main channel of the estuary. We also developed a high-resolution digital elevation (2.5 m cell size) model of the estuary derived from airborne light detection and ranging (LIDAR) and aerial imagery to estimate inundation dynamics within the tidal creek, and related the timing of inundation in various habitats to the timing of fish immigration to and emigration from the creek. Over 50% of all tagged fish were moving in and out of the creek at a threshold level when 50% of the mangrove forest became flooded. Individuals of all four species moved into and out of the tidal creek repeatedly at different times depending on species and size, indicating strong residential behaviour within the estuary. The main activity of fishes was at night time. Manual interpretation of video from >700 fish sightings at three different mangrove sites confirmed the findings of the stationary PIT system, that the function of shelter vs food in mangrove habitat may be size dependent. Our established techniques assess the spatial ecology
Boateng, S.
2006-05-01
The purpose of this study was to monitor the water quality in two creeks in Northern Kentucky. These are the Banklick Creek in Kenton County and the Woolper Creek in Boone County, Kentucky. The objective was to evaluate the effect of landuse and other external factors on surface water quality. Landuse within the Banklick watershed is industrial, forest and residential (urban) whereas that of Woolper Creek is agricultural and residential (rural). Two testing sites were selected along the Banklick Creek; one site was upstream the confluence with an overflow stream from an adjacent lake; the second site was downstream the confluence. Most of the drainage into the lake is over a near-by industrial park and the urban residential areas of the cities of Elsmere and Erlanger, Kentucky. Four sampling locations were selected within the Woolper Creek watershed to evaluate the effect of channelization and subsequent sedimentation on the health of the creek. Water quality parameters tested for include dissolved oxygen, phosphates, chlorophyll, total suspended sediments (TSS), pH, oxidation reduction potential (ORP), nitrates, and electrical conductivity. Sampling and testing were conducted weekly and also immediately after storm events that occurred before the regular sampling dates. Sampling and testing proceeded over a period of 29 weeks. Biological impact was determined, only in Woolper Creek watershed, by sampling benthic macroinvertebrates once every four weeks. The results showed significant differences in the water quality between the two sites within the Banklick Creek. The water quality may be affected by the stream overflow from the dammed lake. Also, channelization in the Woolper Creek seemed to have adverse effects on the water quality. A retention pond, constructed to prevent sediments from flowing into the Woolper Creek, did not seem to be effective. This is because the water quality downstream of the retention pond was significantly worse than that of the
Radiological tracing for historical patterns of polychlorinated biphenyls in creek ecosystem
International Nuclear Information System (INIS)
Tiwari, M.; Bhangare, R.C.; Ajmal, P.Y.; Sahu, S.K.; Pandit, G.G.
2014-01-01
The marine sediments act like sink for most of the pollutants entering the aquatic environment. It becomes more critical in the case of creek ecosystem due to its landlocked and relatively stagnant nature. Various persistent organic pollutants (POPs) like polychlorinated biphenyls (PCBs) are brought into the creek in the form of dissolved and particulate fluxes from industrial effluents, sewerage discharge, urban runoff from the city, spillage, disposal and chemical weathering. PCBs cycle between sediment, water, air and soil. Studying the historical patterns of these toxic pollutants depositions in sediment cores have several applications. They throw light on the chronological inputs of the pollutants in the marine body. Natural radionuclides like 210 Pb act as tracers for determining the historical patterns of these pollutants in different sediment layers. Determining the activities of these radionuclides is useful for determining the age of sediment layers from the sedimentation rates. The unsupported 210 Pb activity of the Thane creek sediments was determined and modeled for assigning the age to different layers of the cores contaminated with PCBs. The unsupported activity of 210 Pb tracer was found to decrease with the increase in depth of the sediment layers. This pattern of the 210 Pb activity was used for determining the sedimentation rate and age of the core layers. The CRS model with 210 Pb activity traced the average sedimentation rate in Thane Creek to 0.67 cm/yr. This helped in labeling the age of formation of the deep core sediment layers. The vertical profile of different PCB congener concentrations in the core samples depicts a gradient from top to bottom, which indicates the influence of industrial contributions over the period. Peak concentrations for the congeners were observed at 13-24 depth, which indicates excessive loading of sediment with these compounds during 1970s (20-30 cm) which was the period of the maximum use and production of these
International Nuclear Information System (INIS)
Machado, E.C.; Machado, W.; Patchineelam, S.R.
2012-01-01
A study on the trace elements transfer from tidal water to mangrove sediments from Guanabara Bay (southeastern Brazil) was performed in laboratory microcosms. Sediment cores were covered with tidal water spiked with 137 Cs, 54 Mn and 57 Co during 5-h experiments, and water samples were taken at regular intervals to measure uptake kinetics at the sediment-water interface. At the end of the experiments, the uptake and diffusional penetration into the sediments was evaluated. Half-removal times from water to sediments were slightly higher for 137 Cs (3.4 ± 1.7 h) than observed for 54 Mn (2.3 ± 0.2 h) and 57 Co (2.6 ± 1.1 h). After these experiments, all radioisotopes presented decreasing activities with increasing sediment depth, being the distribution of 137 Cs indicative of higher diffusion within the upper 2 cm. This study on the removal of 137 Cs, 54 Mn and 57 Co from tidal water by mangrove sediments suggests that while 57 Co and 54 Mn presented closer behaviors, there was a slightly higher mobility of 137 Cs. (author)
Hydrocarbon pollution from marinas in estuarine sediments
Voudrias, Evangelos A.; Smith, Craig L.
1986-03-01
A measure of the impact of marinas on three Eastern Virginia estuarine creeks was obtained by a study of hydrocarbons in their sediments. Two of the creeks support considerable marine activity, including pleasure boat marinas, boat repair facilities, and commercial fishing operations. The third creek, which served as a control, is seldom used by boats, and is surrounded by marsh and woodland. Sediments from the creeks with marinas contained significantly higher levels of both aromatic and aliphatic hydrocarbons than did the control. Differences in the concentrations of certain oil-pollution indicators, such as the 17α,21β-hopane homologs and phytane, and low molecular weight aromatic hydrocarbons, are indicative of light petroleum fractions. Most of the aromatic hydrocarbons from all creeks, however, appear to have a pyrogenic origin. Although hydrocarbons from three probable origins (petroleum, pyrogenesis, and recent biosynthesis) were detected in all locations, the petroleum-derived and pyrogenic hydrocarbons were of only minor importance relative to the biogenic hydrocarbons in the control creek.
Digital Repository Service at National Institute of Oceanography (India)
Shirodkar, P.V.; Pradhan, U.K.; Fernandes, D.; Haldankar, S.R.; Rao, G.S.
of fertilizer and raw materials; petroleum, oil and lubricants (POL) and the boat traffic. Strong macro tidal currents increase turbidity and TSS, while the high salinity water from creek tributaries formed from intense evaporation during summer, and the seepage...
Characterization of surface water contaminants in the Clinch River and Poplar Creek
International Nuclear Information System (INIS)
Ford, C.; Madix, S.; Rash, C.
1995-01-01
Surface waters in the Clinch River and Poplar Creek have been contaminated by activities on the DOE's Oak Ridge Reservation throughout the more than 50 year history of Oak Ridge. Though the Clinch River and Poplar Creek drainage areas are contaminated with heavy metals, organics and radionuclides, public access to these sites is not restricted. The investigation, divided into discrete studies, was tailored to provide a statistically sound picture of contaminants and aqueous toxicity in Poplar Creek, investigate contaminant remobilization from sediments, and determine contaminant levels during a series of ''worst-case'' events. Results for Poplar Creek indicate that average contaminant values were below levels of concern for human health and ecological risk, though contaminant distributions suggest that episodic events contribute sufficiently to system contaminant levels to be of concern. Additionally, water column contaminant levels were significantly higher in particle deposition areas rather than at known contaminant sources. Levels of organic compounds in reference areas to Poplar Creek exceeded those in the Poplar Creek study area. In the Clinch River and Poplar Creek, statistical differences in metal and radionuclide levels from known contaminated areas confirmed previous results, and were used to independently distinguish between sites. Contaminant concentrations were elevated in association with sediments, though no distinction between deposition and remobilization could be made. Due to elevated contaminant levels, and some unexpected contaminant distributions, sites in Poplar Creek and off-channel embayments of the Clinch River were identified that will require additional characterization
Understanding the Influence of Retention Basin on Tidal Dynamics in Tidal Estuaries
Kumar, Mohit; Schuttelaars, Henk; Roos, Pieter
2014-05-01
Both the tidal motion and suspended sediment concentration (SSC) in tidal embayments and estuaries are influenced by anthropogenic (e.g. deepening ) and natural changes. An example of such an estuary is the Ems estuary, situated on the border of the Netherlands and Germany. The mean tidal range towards the end of the Ems estuary has increased from 1.5m in the 1950s to more than 3m in the 1990s while the suspended concentration has increased by a factor 10. To possibly reduce these negative effects, the construction of retention basin(s) (RB) is considered. In this contribution, the influence of location and geometry of RBs on tidal dynamics and SSC is investigated. For this purpose, a three-dimensional semi-analytic idealized model is developed. This model is an extension of the model proposed by Winant (2007) to arbitrary domain and realistic bathymetry with partial slip boundary condition at the bottom. The sea surface elevation (SSE) is calculated numerically using a finite element method. Next, the three-dimensional velocities are calculated by combining the analytically calculated vertical profiles and the gradients of the SSE which are obtained numerically. Firstly, the influence of a RB on the tidal dynamics in an infinitely long, rectangular, frictionless estuary is considered. The SSE decreases when the RB is located between a node and a landward antinode, consistent with the work of Alebregtse et al. (2013). Secondly, an estuary of finite length is connected to a sea. By varying the width of the sea, not only the effect of the distance of the RB to the landward end plays a role, but also the distance to the open sea becomes important. Finally, we discuss the influence of a RB on the tidal motion and initial sediment transport, considering the Ems estuary with realistic bathymetry. Results show that the SSE at the landward end of the Ems estuary decreases for all locations of the RBs. This decrease is most pronounced for the RB which is closest to the end
Colonies of Gyrosigma eximium: a new phenomenon in Arctic tidal flats
Directory of Open Access Journals (Sweden)
Józef Wiktor
2016-10-01
Full Text Available For the first time at Svalbard, a colonial form of the tube-dwelling diatom Gyrosigma eximium was found in summer 2010 in the tidal flats on Spitsbergen at 78°N. The colonies take the form of conical, green structures that are 1–2 cm high and are associated with other diatom taxa and cyanobacteria (Oscillatoriaceae. The diatom colonies were associated with rich meiofauna and apparently act as cohesive factors for the fine sediment. In the Arctic tidal flats, this represents the first observation of long-term sediment stabilization and biological enrichment. Since this first observation, this species has apparently colonized broader areas in Advenentelva's tidal flat.
Howle, James F.; Alpers, Charles N.; Bawden, Gerald W.; Bond, Sandra
2016-07-28
High-resolution ground-based light detection and ranging (lidar), also known as terrestrial laser scanning, was used to quantify the volume of mercury-contaminated sediment eroded from a stream cutbank at Stocking Flat along Deer Creek in the Sierra Nevada foothills, about 3 kilometers west of Nevada City, California. Terrestrial laser scanning was used to collect sub-centimeter, three-dimensional images of the complex cutbank surface, which could not be mapped non-destructively or in sufficient detail with traditional surveying techniques.The stream cutbank, which is approximately 50 meters long and 8 meters high, was surveyed on four occasions: December 1, 2010; January 20, 2011; May 12, 2011; and February 4, 2013. Volumetric changes were determined between the sequential, three-dimensional lidar surveys. Volume was calculated by two methods, and the average value is reported. Between the first and second surveys (December 1, 2010, to January 20, 2011), a volume of 143 plus or minus 15 cubic meters of sediment was eroded from the cutbank and mobilized by Deer Creek. Between the second and third surveys (January 20, 2011, to May 12, 2011), a volume of 207 plus or minus 24 cubic meters of sediment was eroded from the cutbank and mobilized by the stream. Total volumetric change during the winter and spring of 2010–11 was 350 plus or minus 28 cubic meters. Between the third and fourth surveys (May 12, 2011, to February 4, 2013), the differencing of the three-dimensional lidar data indicated that a volume of 18 plus or minus 10 cubic meters of sediment was eroded from the cutbank. The total volume of sediment eroded from the cutbank between the first and fourth surveys was 368 plus or minus 30 cubic meters.
WATER QUALITY ANALYSIS OF AGRICULTURALLY IMPACTED TIDAL BLACKBIRD CREEK, DELAWARE
Directory of Open Access Journals (Sweden)
Matthew Stone
2016-11-01
Full Text Available Blackbird Creek, Delaware is a small watershed in northern Delaware that has a significant proportion of land designated for agricultural land use. The Blackbird Creek water monitoring program was initiated in 2012 to assess the condition of the watershed’s habitats using multiple measures of water quality. Habitats were identified based on percent adjacent agricultural land use. Study sites varying from five to fourteen were sampled biweekly during April and November, 2012-2015. Data were analyzed using principal component analysis and generalized linear modeling. Results from these first four years of data documented no significant differences in water quality parameters (dissolved oxygen, pH, temperature, salinity, inorganic nitrate, nitrite, ammonia, orthophosphate, alkalinity, and turbidity between the two habitats, although both orthophosphate and turbidity were elevated beyond EPA-recommended values. There were statistically significant differences for all of the parameters between agriculture seasons. The lack of notable differences between habitats suggests that, while the watershed is generally impacted by agricultural land use practices, there appears to be no impact on the surface water chemistry. Because there were no differences between habitats, it was concluded that seasonal differences were likely due to basic seasonal variation and were not a function of agricultural land use practices.
Land claim and loss of tidal flats in the Yangtze Estuary.
Chen, Ying; Dong, Jinwei; Xiao, Xiangming; Zhang, Min; Tian, Bo; Zhou, Yunxuan; Li, Bo; Ma, Zhijun
2016-04-01
Tidal flats play a critical role in supporting biodiversity and in providing ecosystem services but are rapidly disappearing because of human activities. The Yangtze Estuary is one of the world's largest alluvial estuaries and is adjacent to the most developed economic zone in China. Using the Yangtze Estuary as a study region, we developed an automatic algorithm to estimate tidal flat areas based on the Land Surface Water Index and the Normalized Difference Vegetation Index. The total area of tidal flats in the Yangtze Estuary has decreased by 36% over the past three decades, including a 38% reduction in saltmarshes and a 31% reduction in barren mudflats. Meanwhile, land claim has accumulated to 1077 km(2), a value that exceeds the area of the remaining tidal flats. We divided the Yangtze Estuary into Shanghai and Jiangsu areas, which differ in riverine sediment supply and tidal flat management patterns. Although land claim has accelerated in both areas, the decline in tidal flat area has been much greater in Jiangsu than in Shanghai because of abundant supplies of sediment and artificial siltation in the latter area. The results highlight the need for better coastal planning and management based on tidal flat dynamics.
Environmental and radiological pollution in creeks sediment and water from Duhok, Iraq
International Nuclear Information System (INIS)
Abdullah, K.M.S.
2012-01-01
The activity concentrations of terrestrial (/sup 226/Ra, /sup 232/Th and /sup 40/K) and anthropogenic gamma emitting radionuclides (/sup 137/Cs) have been measured in 28 creek water and sediment samples randomly selected in different locations of Duhok governorate. The governorate is located in the northwest Kurdistan region of Iraq. Determination of the human health risk from the three exposure pathways (External radiation, Inhalation and Ingestion) was carried out. In addition, the chemical analysis was performed for the 13 surface water samples for reliability of physical results. Gamma spectroscopy system with a shielded well type NaI(TI) detector used for 40000 sec per sample. The data analysis included elemental concentrations, air absorbed dose rate, annual effective dose rate and external hazard index (radium equivalent activity). The average of 49.81+-1.69 nGyh/sup -1/ in sediment and 21.19+-1.32 nGyh/sup -1/ in water samples were below the world average value of 57nGyh/sup -1/. The corresponding annual effective dose rates outdoor estimated for sediment and surface water were 61.13+-2.1 macro Svy/sup -1/ and 26.01+-1.62 macro Svy/sup -1/ respectively. The calculated external hazard indexes (Hex) 0.29+0.01 for sediment and 0.112+0.007 surface water samples. These values showed that all samples were well below the hazard limit of unity. The RESRAD-6.5 computer code was used to analyze the dose per unit release of a specified radionuclide and the health risk from the three exposure pathways. RESRAD code showed over estimation of the results of annual effective dose rates, even though the results were within the background level. The average value of activity concentrations of the radionuclides of sediment samples by the code was 0.108 mSvy/sup -1/ compared to our calculations. The probability of human cancer risk lifetime of a hypothetical contamination consisted of the highest value of the activity concentrations of terrestrial radionuclides and /sup 137/Cs
Laceby, J. Patrick; Olley, Jon
2013-04-01
Moreton Bay, in South East Queensland, Australia, is a Ramsar wetland of international significance. A decline of the bay's ecosystem health has been primarily attributed to sediments and nutrients from catchment sources. Sediment budgets for three catchments indicated gully erosion dominates the supply of sediment in Knapp Creek and the Upper Bremer River whereas erosion from cultivated soils is the primary sediment source in Blackfellow Creek. Sediment tracing with fallout-radionuclides confirmed subsoil erosion processes dominate the supply of sediment in Knapp Creek and the Upper Bremer River whereas in Blackfellow Creek cultivated and subsoil sources contribute >90% of sediments. Other sediment properties are required to determine the relative sediment contributions of channel bank, gully and cultivated sources in these catchments. The potential of total organic carbon (TOC), total nitrogen (TN), and carbon and nitrogen stable isotopes (δ13C, δ15N) to conservatively discriminate between subsoil sediment sources is presented. The conservativeness of these sediment properties was examined through evaluating particle size variations in depth core soil samples and investigating whether they remain constant in source soils over two sampling occasions. Varying conservative behavior and source discrimination was observed. TN in the
Basavaiah, N; Mohite, R D; Singare, P U; Reddy, A V R; Singhal, R K; Blaha, U
2017-05-15
A study on vertical distribution of magnetic susceptibility, carcinogenic and endocrine disrupting PAHs was performed in the reclaimed mudflat sediments adjacent to the Thane Creek of Mumbai. The 5-rings PAHs and ΣC-PAHs were more dominant at 120cm depth contributing 52.23% and 60.19% respectively to ∑PAHs. The average ratio values of LMW/HMW PAHs (0.58); Fla/(Fla+Pyr) (0.50); Ant/(Ant+Phe) (0.50); BaA/(Chry+BaA) (0.48); BaP/BghiP (2.06), Phe/Ant (1.03) and BaA/Chr (0.93) indicate that the PAH contamination might have raised due to inefficient combustion and pyrogenic emissions during the open burning of solid waste in the vicinity. This was further supported by the anthropogenic ferri(o)magnetic loading over the last 100years influencing the Creek sediments. The PAHs toxicity estimation was performed by calculating the toxic equivalent quantity (TEQ) value of 8.62ng TEQ/g which was below the safe level (600ng TEQ/g) suggested by the Canadian risk-based soil criterion for protection of human health. Copyright © 2017 Elsevier Ltd. All rights reserved.
Digital Repository Service at National Institute of Oceanography (India)
Nair, R.R.; Hashimi, N.H.; Rao, V.P
and clay minerals. The distinct differences have resulted because the high-velocity (2 to 2.5 knots) tidal stream at the gulf mouth acts as a dynamic barrier inhibiting sediment transport across the month. Differences in the distribution of sand size...
International Nuclear Information System (INIS)
Teuchies, J.; Deckere, E. de; Bervoets, L.; Meynendonckx, J.; Regenmortel, S. van; Blust, R.; Meire, P.
2008-01-01
A historical input of trace metals into tidal marshes fringing the river Scheldt may be a cause for concern. Nevertheless, the specific physicochemical form, rather than the total concentration, determines the ecotoxicological risk of metals in the soil. In this study the effect of tidal regime on the distribution of trace metals in different compartments of the soil was investigated. As, Cd, Cu and Zn concentrations in sediment, pore water and in roots were determined along a depth profile. Total sediment metal concentrations were similar at different sites, reflecting pollution history. Pore water metal concentrations were generally higher under less flooded conditions (mean is (2.32 ± 0.08) x 10 -3 mg Cd L -1 and (1.53 ± 0.03) x 10 -3 mg Cd L -1 ). Metal concentrations associated with roots (mean is 202.47 ± 2.83 mg Cd kg -1 and 69.39 ± 0.99 mg Cd kg -1 ) were up to 10 times higher than sediment (mean is 20.48 ± 0.19 mg Cd kg -1 and 20.42 ± 0.21 mg Cd kg -1 ) metal concentrations and higher under dryer conditions. Despite high metal concentrations associated with roots, the major part of the metals in the marsh soil is still associated with the sediment as the overall biomass of roots is small compared to the sediment. - Pore water metal concentrations and metal root plaque concentration are influenced by the tidal regime
Seasonal abundance of epipelic algae and sediment parameters of ...
African Journals Online (AJOL)
Amadi-Ama creek is located close to sources of wastes which are introduced into the creek thus altering the physico-chemical parameters and the aquatic biota of the creek due to variation in nutrient load of the water. The seasonal abundance of epipelic algae and sediment parameters of Amadi-Ama Creek were ...
Road construction on Caspar Creek watersheds --- 10-year report on impact
J. S. Krammes; David M. Burns
1973-01-01
In 1960, Federal and State agencies jointly started a long-term study of the effects of logging and road building on streamflow, sedimentation, aquatic habitat, and fish populations on two watersheds of Caspar Creek, in northern California. The experimental watersheds are the North and South Forks of the Creek. The data being collected consist of continuous streamflow...
Properties of active tidal bedforms
DEFF Research Database (Denmark)
Winter, Christian; Lefebvre, Alice; Becker, Marius
2016-01-01
Bedforms of various shapes and sizes are ubiquitous in tidal channels, inlets and estuaries. They constitute a form roughness which has a large scale effect on the hydrodynamics and sediment transport of coastal environments. It has been shown that this form roughness can be expressed in terms...
Watson, G J; Murray, J M; Schaefer, M; Bonner, A; Gillingham, M
2017-09-01
Bait collection is a multibillion dollar worldwide activity that is often managed ineffectively. For managers to understand the impacts on protected inter-tidal mudflats and waders at appropriate spatial scales macrofaunal surveys combined with video recordings of birds and bait collectors were undertaken at two UK sites. Dug sediment constituted approximately 8% of the surveyed area at both sites and is less muddy (lower organic content) than undug sediment. This may have significant implications for turbidity. Differences in the macrofaunal community between dug and undug areas if the same shore height is compared as well as changes in the dispersion of the community occurred at one site. Collection also induces a 'temporary loss of habitat' for some birds as bait collector numbers negatively correlate with wader and gull abundance. Bait collection changes the coherence and ecological structure of inter-tidal mudflats as well as directly affecting wading birds. However, as β diversity increased we suggest that management at appropriate hectare/site scales could maximise biodiversity/function whilst still supporting collection. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.
Stream sediment sampling and analysis. Final report
International Nuclear Information System (INIS)
Means, J.L.; Voris, P.V.; Headington, G.L.
1986-04-01
The objectives were to sample and analyze sediments from upstream and downstream locations (relative to the Goodyear Atomic plant site) of three streams for selected pollutants. The three streams sampled were the Scioto River, Big Beaver Creek, and Big Run Creek. Sediment samples were analyzed for EPA's 129 priority pollutants (Clean Water Act) as well as isotopic uranium ( 234 U, 235 U, and 238 U) and technetium-99
Effects of freshwater leaching on potential bioavailability of heavy metals in tidal flat soils.
Li, Hui; Lu, Jun; Li, Qu-Sheng; He, Bao-Yan; Mei, Xiu-Qin; Yu, Dan-Ping; Xu, Zhi-Min; Guo, Shi-Hong; Chen, Hui-Jun
2016-02-01
Leaching experiments were conducted to investigate the effects of desalination levels and sediment depths on potential bioavailability of heavy metal (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in tidal flat soils. The data showed that both the desalination levels (p soil depths (p toxicity to benthic organisms than high desalination treatment. Since these reclaimed tidal flats with low desalinisation are suitable for saline water aquaculture, transforming the present land use of reclaimed tidal flats from fresh water aquaculture into saline water aquaculture may reduce health risk of heavy metals remained in sediments. These results will also contribute to our understanding of the dynamic behavior of heavy metals in the reclamation of tidal flats during leaching and the role of the ratio of SEM/AVS predictions on assessing the ecological risks of reclaimed tidal flats.
Chen, Wei; de Swart, Huib E.
2018-03-01
This study investigates the longitudinal variation of lateral entrapment of suspended sediment, as is observed in some tidal estuaries. In particular, field data from the Yangtze Estuary are analysed, which reveal that in one cross-section, two maxima of suspended sediment concentration (SSC) occur close to the south and north sides, while in a cross-section 2 km down-estuary, only one SSC maximum on the south side is present. This pattern is found during both spring tide and neap tide, which are characterised by different intensities of turbulence. To understand longitudinal variation in lateral trapping of sediment, results of a new three-dimensional exploratory model are analysed. The hydrodynamic part contains residual flow due to fresh water input, density gradients and Coriolis force and due to channel curvature-induced leakage. Moreover, the model includes a spatially varying eddy viscosity that accounts for variation of intensity of turbulence over the spring-neap cycle. By imposing morphodynamic equilibrium, the two-dimensional distribution of sediment in the domain is obtained analytically by a novel procedure. Results reveal that the occurrence of the SSC maxima near the south side of both cross-sections is due to sediment entrapment by lateral density gradients, while the second SSC maximum near the north side of the first cross-section is by sediment transport due to curvature-induced leakage. Coriolis deflection of longitudinal flow also contributes the trapping of sediment near the north side. This mechanism is important in the upper estuary, where the flow due to lateral density gradients is weak.
Contaminated sediment transport during floods
International Nuclear Information System (INIS)
Fontaine, T.A.
1992-01-01
Over the past 48 years, operations and waste disposal activities at Oak Ridge National Laboratory have resulted in the contamination of parts of the White Oak Creek catchment. The contaminants presenting the highest risk to human health and the environment are particle reactive and are associated with the soils and sediments in the White Oak Creek drainage system. The erosion of these sediments during floods can result in the transport of contaminants both within the catchment and off-site into the Clinch River. A data collection program and a modeling investigation are being used to evaluate the probability of contaminated sediment transport during floods and to develop strategies for controlling off-site transport under present and future conditions
In situ erosion of cohesive sediment
International Nuclear Information System (INIS)
Williamson, H.J.; Ockenden, M.C.
1993-01-01
There has been increasing interest in tidal power schemes and the effect of a tidal energy barrage on the environment. A large man-made environmental change, such as a barrage, would be expected to have significant effects on the sediment distribution and stability of an estuary and these effects need to be assessed when considering a tidal barrage project. This report describes the development of apparatus for in-situ measurements of cohesive sediment erosion on inter-tidal mudflats. Development of the prototype field erosion bell and field testing was commissioned on behalf of the Department of Trade and Industry by the Energy Technology Support Unit (ETSU). This later work commenced in August 1991 and was completed in September 1992. (Author)
Rathburn, S. L.; McElroy, B. J.; Wohl, E.; Sutfin, N. A.; Huson, K.
2014-12-01
During mid-September 2013, approximately 360 mm of precipitation fell in the headwaters of the North St. Vrain drainage basin, Front Range, CO. Debris flows on steep hillslopes and extensive flooding along North St. Vrain Creek resulted in extreme sedimentation within Ralph Price Reservoir, municipal water supply for the City of Longmont. The event allows comparison of historical sedimentation with that of an unusually large flood because 1) no reservoir flushing has been conducted since dam construction, 2) reservoir stratigraphy chronicles uninterrupted delta deposition, and 3) this is the only on-channel reservoir with unimpeded, natural sediment flux from the Continental Divide to the mountain front in a basin with no significant historic flow modifications and land use impacts. Assessing the flood-related sedimentation prior to any dredging activities included coring the reservoir delta, a bathymetric survey of the delta, resistivity and ground penetrating radar surveys of the subaerial inlet deposit, and surveying tributary deposits. Over the 44-year life of the reservoir, two-thirds of the delta sedimentation is attributed to extreme discharges from the September 2013 storm. Total storm-derived reservoir sedimentation is approximately 275,000 m3, with 81% of that within the gravel-dominated inlet and 17% in the delta. Volumes of deposition within reservoir tributary inlets is negatively correlated with contributing area, possibly due to a lack of storage in these small basins (1-5 km2). Flood-related reservoir sedimentation will be compared to other research quantifying volumes from slope failures evident on post-storm lidar. Analysis of delta core samples will quantify organic carbon flux associated with the extreme discharge and develop a chronology of flood and fire disturbances for North St. Vrain basin. Applications of similar techniques are planned for two older Front Range reservoirs affected by the September flooding to fill knowledge gaps about
Turnewitsch, Robert; Falahat, Saeed; Stehlikova, Jirina; Oguri, Kazumasa; Glud, Ronnie N.; Middelboe, Mathias; Kitazato, Hiroshi; Wenzhöfer, Frank; Ando, Kojiro; Fujio, Shinzou; Yanagimoto, Daigo
2014-08-01
In addition to high hydrostatic pressure, scarcity of food is viewed as a factor that limits the abundance and activity of heterotrophic organisms at great ocean depths, including hadal trenches. Supply of nutritious food largely relies on the flux of organic-rich particulate matter from the surface ocean. It has been speculated that the shape of hadal trenches helps to ‘funnel' particulate matter into the deeper parts of the trench, leading to sediment ‘focussing' and improved benthic food supply. Here we investigate for five Northwest Pacific trenches the efficiency of sediment focussing by evaluating ratios of measured (sediment-derived) and expected (water-column-derived) sedimentary inventories of the naturally occurring and radioactive particulate-matter tracer 210Pbxs. The sites comprise a broad range of surface-ocean productivity and physical-oceanographic regimes. Across the five trench-axis settings the inventory ratio varies between 0.5 and 4.1, with four trench-axis settings having ratios>1 (sediment focussing) and one trench-axis setting a ratiowinnowing). Although the fluid- and sediment-dynamical forcing behind sediment focussing remains unclear, this study finds evidence for another mechanism that is superimposed on, and counteracts, the focussing mechanism. This superimposed mechanism is related to higher-frequency (tidal, near-inertial) fluid dynamics. In particular, there is evidence for a strong and negative relation between the intensity of propagating internal tides and the extent of sediment focussing in the trench-axis. The relation can be approximated by a power function and the most intense drop in sediment focussing already occurs at moderate internal-tide intensities. This suggests that propagating internal tides may have a subtle but significant influence on particulate-matter dynamics and food supply in hadal trenches in particular, but possibly also in the deep seas in general. A mechanism for the influence of internal tides on
Review of sediment stabilisation techniques
International Nuclear Information System (INIS)
1992-01-01
The best sites for tidal power schemes are found in estuaries with high tidal ranges which have complex ecosystems and include a wide and diverse range of habitats. If the tidal power is to be developed, therefore, it is important to determine the likely effect on the environment and any ameliorative measures which may be necessary. One possible change is likely to be the erosion of material from the bed or shoreline of the estuary, and possibly the adjacent coast. This is of particular concern if intertidal sandflats, mudflats and saltmarsh are affected, as these are important wildlife habitats. Moreover, largescale movement of sediments would be undesirable. Results of a desk study of methods of preventing the erosion of sediment deposits in or near an estuary in the conditions that may occur following the construction of a tidal power barrage are presented. (author)
Hydrologic Data for Deep Creek Lake and Selected Tributaries, Garrett County, Maryland, 2007-08
Banks, William S.L.; Davies, William J.; Gellis, Allen C.; LaMotte, Andrew E.; McPherson, Wendy S.; Soeder, Daniel J.
2010-01-01
Introduction Recent and ongoing efforts to develop the land in the area around Deep Creek Lake, Garrett County, Maryland, are expected to change the volume of sediment moving toward and into the lake, as well as impact the water quality of the lake and its many tributaries. With increased development, there is an associated increased demand for groundwater and surface-water withdrawals, as well as boat access. Proposed dredging of the lake bottom to improve boat access has raised concerns about the adverse environmental effects such activities would have on the lake. The Maryland Department of Natural Resources (MDDNR) and the U.S. Geological Survey (USGS) entered into a cooperative study during 2007 and 2008 to address these issues. This study was designed to address several objectives to support MDDNR?s management strategy for Deep Creek Lake. The objectives of this study were to: Determine the current physical shape of the lake through bathymetric surveys; Initiate flow and sediment monitoring of selected tributaries to characterize the stream discharge and sediment load of lake inflows; Determine sedimentation rates using isotope analysis of sediment cores; Characterize the degree of hydraulic connection between the lake and adjacent aquifer systems; and Develop an estimate of water use around Deep Creek Lake. Summary of Activities Data were collected in Deep Creek Lake and in selected tributaries from September 2007 through September 2008. The methods of investigation are presented here and all data have been archived according to USGS policy for future use. The material presented in this report is intended to provide resource managers and policy makers with a broad understanding of the bathymetry, surface water, sedimentation rates, groundwater, and water use in the study area. The report is structured so that the reader can access each topic separately using any hypertext markup (HTML) language reader. In order to establish a base-line water-depth map of
Initial formation of channels and shoals in a short tidal embayment
Schuttelaars, H.M.; Swart, H.E. de
1997-01-01
It is demonstrated by using a simple model that bedforms in a short tidal embayment can develop due to a positive feedback between tidal currents sediment transport and bedforms The system is forced by a prescribed free surface elevations at the entrance of the embayment The water motions are
Algal stabilisation of estuarine sediments
International Nuclear Information System (INIS)
1992-01-01
The presence of benthic microalgae can increase the stability of intertidal sediments and influence sediment fluxes within an estuarine environment. Therefore the relative importance of algal stabilisation needs to be understood to help predict the effects of a tidal barrage. The objectives of this study are: to assess the significance of stabilisation of sediments by algae, in relation to the changes in hydrodynamic and sedimentological regimes arising from the construction of tidal power barrages; to identify a reliable and meaningful method of measuring the effectiveness, including duration, of algal binding on sediment stability, and to relate this method to other methods of measuring critical erosion velocity and sediment shear strength; to undertake a series of field experiments investigating the effect of algae on binding sediments and the parameters which could potentially influence such binding and to develop a predictive method for the assessment of sediment stabilisation by algal binding. This report contains plates, figures and tables. (author)
Directory of Open Access Journals (Sweden)
A. Mrutu
2013-12-01
Full Text Available Mangrove wetlands are important biological systems that usually filter out organic and inorganic contaminants from the wastewaters before entering the ocean. Our previous work showed that sediments of the Msimbazi Creek wetland are contaminated with heavy metals and the amounts decreased with increasing depth. However, the hidden relationships between the heavy metals and clay particles were not fully understood based on the numerical data. Therefore this work used the data from literature and the Statistical Package for Social Sciences (SPSS software to study how significant the relationships are and predict the sources of heavy metals and clays. The results showed that Cd is the only metal that showed insignificant correlations with other heavy metals (with Pb and Zn while the rest of heavy metals exhibited significant positive correlation (except Pb vs. Ni. Cluster analysis classified the heavy metals based on the concentration and the first 50 cm cores (0-50 cm had higher heavy metals and % clay than the second 50 cm cores (51-100 cm. The results from the factor analysis suggests that Pb, Cd, Ni, and clay owe their source mostly from anthropogenic activities while Fe, Co, Cr, Zn and sand come from both anthropogenic and natural sources. These results support our previous suggestions that heavy metals and clays found in this wetland have mostly anthropogenic origin. However, we recommend isotopic tracing studies in order to accurately identify the origins of the heavy metals and clays in sediments of Msimbazi Creek mangrove wetland.
Directory of Open Access Journals (Sweden)
Hideki Tatsumoto
2004-01-01
Full Text Available An artificial tidal flat was prepared for the mitigation tool on coastal environment. However, it is considered that most of the flat was not restored to the sufficient amenities for aquatic living things, migratory birds, etc. because none of the ecological mechanisms were understood or planned for. It is therefore investigated in this paper that historical transition factors in ecosystem structure are selected and traced with the diffusion of a public sewerage system, and with environmental factors such as water quality, sediment condition, and aquatic producers in the Yatsu Tidal Flat. As a result, it can be defined that the tidal flat, just like a lagoon, was formed artificially with reclamation and development of its circumference at the first step of transition; the water quality and sediment condition gradually became brackish water and muddy sediment conditions, interactively. The ecosystem pyramid forming orderly layers according to trophic level appeared as a high-bio-production potential in its tidal flat. In the second step, i.e., in recent years, the characteristics of water quality and sediment conditions evolved into a foreshore tidal flat, namely, conditions in the flat observed were that the progression of water included a high concentration of chloride ion as seawater and sediment conditions became sandy. Because of that, the inflowing fresh water and organic mater from the land area decreased with the improvement of the public sewerage system. The ecosystem pyramid was distorted into a chaos pyramid, with inversion of Ulva spp.
Tatsumoto, Hideki; Ishii, Yuichi; Machida, Motoi; Taki, Kazuo
2004-05-11
An artificial tidal flat was prepared for the mitigation tool on coastal environment. However, it is considered that most of the flat was not restored to the sufficient amenities for aquatic living things, migratory birds, etc. because none of the ecological mechanisms were understood or planned for. It is therefore investigated in this paper that historical transition factors in ecosystem structure are selected and traced with the diffusion of a public sewerage system, and with environmental factors such as water quality, sediment condition, and aquatic producers in the Yatsu Tidal Flat. As a result, it can be defined that the tidal flat, just like a lagoon, was formed artificially with reclamation and development of its circumference at the first step of transition; the water quality and sediment condition gradually became brackish water and muddy sediment conditions, interactively. The ecosystem pyramid forming orderly layers according to trophic level appeared as a high-bio-production potential in its tidal flat. In the second step, i.e., in recent years, the characteristics of water quality and sediment conditions evolved into a foreshore tidal flat, namely, conditions in the flat observed were that the progression of water included a high concentration of chloride ion as seawater and sediment conditions became sandy. Because of that, the inflowing fresh water and organic mater from the land area decreased with the improvement of the public sewerage system. The ecosystem pyramid was distorted into a chaos pyramid, with inversion of Ulva spp.
Observations of ebb flows on tidal flats: Evidence of dewatering?
Rinehimer, J. P.; Thomson, J. M.; Chickadel, C.
2010-12-01
Incised channels are a common morphological feature of tidal flats. When the flats are inundated, flows are generally forced by the tidally varying sea surface height. During low tide, however, these channels continue to drain throughout flat exposure even without an upstream source of water. While the role of porewater is generally overlooked due to the low permeability of marine muds, it remains the only potential source of flows through the channels during low tide. In situ and remotely sensed observations (Figure 1) at an incised channel on a tidal flat in Willapa Bay from Spring 2010 indicate that dewatering of the flats may be driving these low tide flows. High resolution Aquadopp ADCP velocity profiles are combined with observations from tower-based infrared (IR) video to produce a complete time series of surface velocity measurements throughout low tide. The IR video observations provide a measurement of surface currents even when the channel depth is below the blanking distance of the ADCP (10 cm). As the depth within the channel drops from 50 cm to 10 cm surface velocities increase from 10 cm/s to 60 cm/s even as the tide level drops below the channel flanks and the flats are dry. As the drainage continues, the temperature of the flow rises throughout low tide, mirroring temperatures within the sediment bed on the tidal flat. Drainage salinity falls despite the lack of any freshwater input to the flat indicating that less saline porewater may be the source. The likely source of the drainage water is from the channel flanks where time-lapse video shows slumping and compaction of channel sediments. Velocity profiles, in situ temperatures, and IR observations also are consistent with the presence of fluid muds and a hyperpycnal, density driven outflow at the channel mouth highlighting a possible pathway for sediment delivery from the flats to the main distributary channels of the bay. Figure 1: Time series of tidal flat channel velocities and temperatures
Kumpf, L. L.; Kineke, G. C.; Carlson, B.; Mullane, M.
2017-12-01
Avulsions on the fine-grained Huanghe delta have left it scarred with traces of abandoned distributary channels that become intertidal systems, open to water and sediment exchange with the sea. In 1996, an engineered avulsion of the Huanghe left a 30 km long abandoned channel to the south of the modern active river channel. Though all fluvial input was cut off, present-day sedimentation on the new tidal flats has been observed at rates around 2 cm/yr. The source must be suspended-sediment from the Bohai Sea conveyed by the tidal channel network, but the mechanisms promoting sediment import are unknown. Possible mechanisms include (A) import sourced from the sediment-rich buoyant coastal plume, (B) wave resuspension on the shallow shelf, (C) reverse-estuarine residual circulation in the tidal channel, and (D) tidal asymmetry in the channel. Over three summers, in situ measurements of current velocity, suspended-sediment concentration (SSC), and wave climate were made on the delta front, and measurements of velocity, SSC, and salinity were made within the tidal channel. Results suggest that the buoyant plume from the active Huanghe channel can transport sediment south toward the tidal channel mouth (A). Additionally, wave resuspension (B) takes place on the subaqueous topset beds when the significant wave height exceeds 1 m, providing potential sources of suspended-sediment to the tidal channel. Within the abandoned channel, the tidal channel can become hypersaline and exhibit reverse-estuarine circulation (C), which would promote import of turbid coastal water near the surface. Time-series of velocity in the tidal channel indicate that ebb currents are consistently higher than flood currents through the spring-neap cycle (D), with maximum velocities exceeding 1 m/s and corresponding maximum SSC reaching 2 g/L during spring tide. While ebb dominance would typically tend to flush the system of its sediment over time, sediment supplied to the tidal flats may not be
Residential runoff as a source of pyrethroid pesticides to urban creeks
Energy Technology Data Exchange (ETDEWEB)
Weston, D.P. [Department of Integrative Biology, University of California, 3060 Valley Life Sciences Building, Berkeley, CA 94720-3140 (United States)], E-mail: dweston@berkeley.edu; Holmes, R.W. [Water Branch, California Department of Fish and Game, 830 S Street, Sacramento, CA 95811 (United States)], E-mail: rholmes@dfg.ca.gov; Lydy, M.J. [Fisheries and Illinois Aquaculture Center, Department of Zoology, Southern Illinois University, 171 Life Sciences II, Carbondale, IL 62901 (United States)], E-mail: mlydy@siu.edu
2009-01-15
Pyrethroid pesticides occur in urban creek sediments at concentrations acutely toxic to sensitive aquatic life. To better understand the source of these residues, runoff from residential neighborhoods around Sacramento, California was monitored over the course of a year. Pyrethroids were present in every sample. Bifenthrin, found at up to 73 ng/L in the water and 1211 ng/g on suspended sediment, was the pyrethroid of greatest toxicological concern, with cypermethrin and cyfluthrin of secondary concern. The bifenthrin could have originated either from use by consumers or professional pest controllers, though the seasonal pattern of discharge from the drain was more consistent with professional use as the dominant source. Stormwater runoff was more important than dry season irrigation runoff in transporting pyrethroids to urban creeks. A single intense storm was capable of discharging as much bifenthrin to an urban creek in 3 h as that discharged over 6 months of irrigation runoff. - Pyrethroid insecticides regularly detected in residential runoff at toxicologically significant concentrations.
Residential runoff as a source of pyrethroid pesticides to urban creeks
International Nuclear Information System (INIS)
Weston, D.P.; Holmes, R.W.; Lydy, M.J.
2009-01-01
Pyrethroid pesticides occur in urban creek sediments at concentrations acutely toxic to sensitive aquatic life. To better understand the source of these residues, runoff from residential neighborhoods around Sacramento, California was monitored over the course of a year. Pyrethroids were present in every sample. Bifenthrin, found at up to 73 ng/L in the water and 1211 ng/g on suspended sediment, was the pyrethroid of greatest toxicological concern, with cypermethrin and cyfluthrin of secondary concern. The bifenthrin could have originated either from use by consumers or professional pest controllers, though the seasonal pattern of discharge from the drain was more consistent with professional use as the dominant source. Stormwater runoff was more important than dry season irrigation runoff in transporting pyrethroids to urban creeks. A single intense storm was capable of discharging as much bifenthrin to an urban creek in 3 h as that discharged over 6 months of irrigation runoff. - Pyrethroid insecticides regularly detected in residential runoff at toxicologically significant concentrations
International Nuclear Information System (INIS)
Suzuki, K.N.; Lopes, R.T.; Machado, E.C.; Machado, W.; Osso, J.A.Jr.
2014-01-01
Mangrove sediment cores sampled from Sepetiba Bay (SE Brazil) were covered with tidal water spiked with 75 Se, 51 Cr and 60 Co to evaluate the removal efficiency of these radiotracers by underlying sediments. Variable time-evolution trends were observed along 115 h experiments, with significant differences between removal efficiencies of all radiotracers observed only after 70 h ( 51 Cr > 60 Co > 75 Se). After an event of 60 Co release back to overlying water, there was a general trend of lower 60 Co removal than observed for other radiotracers during the period from 20 to 54 h. After this event, alternated periods of higher 60 Co and higher 75 Se removal trends were observed, attributed to behavioural differences expected for such anionic and cationic radiotracers. While 75 Se and 51 Cr showed uniform time-evolution curves, as typically found in the literature for most radiotracers, 60 Co removal rates presented oscillations, probably due to sensitivity to changes in redox conditions within underlying sediments. Results evidenced the role of mangrove sediments as trace element sinks, which have implications for coastal water quality and for possible uses of such sediments in wastewater treatment systems. (author)
Suspended sediment and sediment-associated contaminants in San Francisco Bay
Schoellhamer, D.H.; Mumley, T.E.; Leatherbarrow, J.E.
2007-01-01
Water-quality managers desire information on the temporal and spatial variability of contaminant concentrations and the magnitudes of watershed and bed-sediment loads in San Francisco Bay. To help provide this information, the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP) takes advantage of the association of many contaminants with sediment particles by continuously measuring suspended-sediment concentration (SSC), which is an accurate, less costly, and more easily measured surrogate for several trace metals and organic contaminants. Continuous time series of SSC are collected at several sites in the Bay. Although semidiurnal and diurnal tidal fluctuations are present, most of the variability of SSC occurs at fortnightly, monthly, and semiannual tidal time scales. A seasonal cycle of sediment inflow, wind-wave resuspension, and winnowing of fine sediment also is observed. SSC and, thus, sediment-associated contaminants tend to be greater in shallower water, at the landward ends of the Bay, and in several localized estuarine turbidity maxima. Although understanding of sediment transport has improved in the first 10 years of the RMP, determining a simple mass budget of sediment or associated contaminants is confounded by uncertainties regarding sediment flux at boundaries, change in bed-sediment storage, and appropriate modeling techniques. Nevertheless, management of sediment-associated contaminants has improved greatly. Better understanding of sediment and sediment-associated contaminants in the Bay is of great interest to evaluate the value of control actions taken and the need for additional controls. ?? 2007 Elsevier Inc. All rights reserved.
National Research Council Canada - National Science Library
Copeland, Ronald
2000-01-01
.... An existing concrete-lined flood control channel on Corte Madera Creek in Marin County, California lacks a debris basin at its upstream terminus and carries significant bed load through a supercritical flow reach...
Site-specific sediment clean-up objectives developed by the sediment quality triad
International Nuclear Information System (INIS)
Redman, S.; Janisch, T.
1995-01-01
Sediment chemistry, sediment toxicity, and benthic macroinvertebrate community data were collected and evaluated in concert (1) to characterize adverse effects of hydrocarbon and metal contaminants in the sediments of a small inlet of Superior Bay, Lake Superior and a tributary creek and (2) to derive numeric objectives for the clean up of this system. Sediments from reference locations and eight study sites were analyzed for a range of contaminants, including hydrocarbons (measured both as diesel range organics (DRO) and oil and grease), lead, chromium, and ammonia. A range of sediment toxicity was observed across the eight study sites using a variety of tests and endpoints: Hyalella azteca (10 day survival and growth), Chironomus tentans (10 day survival and growth), Ceriodaphnia dubia (48 hour survival), and Daphnia magna (48 hour survival and 10 day survival and reproduction). A range of alterations of the benthic macroinvertebrate community compared with communities from reference locations were observed. Benthic community alterations were summarized quantitatively by taxa richness and Shannon-Weiner mean diversity. Lowest effect levels determined through this study included 150 microg/g dry sediment for DRO (as measured in this study) and 40 microg/g dry sediment for lead. Effects thresholds determined through this study included 1,500 microg/g dry sediment for DRO and 90 microg/g dry sediment for lead. These levels and concentrations measured in relevant reference locations are being used to define objectives for sediment clean up in the inlet and creek
The impacts of land reclamation on suspended-sediment dynamics in Jiaozhou Bay, Qingdao, China
Gao, Guan Dong; Wang, Xiao Hua; Bao, Xian Wen; Song, Dehai; Lin, Xiao Pei; Qiao, Lu Lu
2018-06-01
A three-dimensional, high-resolution tidal model coupled with the UNSW sediment model (UNSW-Sed) based on Finite Volume Coastal Ocean Model (FVCOM) was set up to study the suspended-sediment dynamics and its change in Jiaozhou Bay (JZB) due to land reclamation over the period 1935 to 2008. During the past decades, a large amount of tidal flats were lost due to land reclamation. Other than modulating the tides, the tidal flats are a primary source for sediment resuspensions, leading to turbidity maxima nearshore. The tidal dynamics are dominant in controlling the suspended-sediment dynamics in JZB and have experienced significant changes with the loss of tidal flats due to the land reclamation. The sediment model coupled with the tide model was used to investigate the changes in suspended-sediment dynamics due to the land reclamation from 1935 to 2008, including suspended-sediment concentrations (SSC) and the horizontal suspended-sediment fluxes. This model can predict the general patterns of the spatial and temporal variation of SSC. The model was applied to investigate how the net transport of suspended sediments between JZB and its adjacent sea areas changed with land reclamation: in 1935 the net movement of suspended sediments was from JZB to the adjacent sea (erosion for JZB), primarily caused by horizontal advection associated with a horizontal gradient in the SSC; This seaward transport (erosion for JZB) had gradually declined from 1935 to 2008. If land reclamation on a large scale is continued in future, the net transport between JZB and the adjacent sea would turn landward and JZB would switch from erosion to siltation due to the impact of land reclamation on the horizontal advection of suspended sediments. We also evaluate the primary physical mechanisms including advection of suspended sediments, settling lag and tidal asymmetry, which control the suspended-sediment dynamics with the process of land reclamation.
The Wildcat Creek, a tributary to the Wabash River was identified by the USDA Natural Resources Conservation Service (NRCS) as a priority watershed for its high sediment and nutrient loading contributions to the Mississippi River. As part of the Mississippi River Basin Initiative (MRBI), the incorpo...
Strong tidal modulation of net ecosystem exchange in a salt marsh in North Inlet, South Carolina
O'Halloran, T. L.; Smith, E. M.; Bogoev, I.
2017-12-01
Along the southeastern US, intertidal salt marshes represent a critical habitat at the interface of the terrestrial and marine environments and perform a variety of ecological functions and services that make them of great economic importance for coastal communities They provide essential fish and shellfish habitat, with a majority of all commercially- and recreationally important fish species being dependent on intertidal marsh habitat during some portion of their life cycle. The penaeid shrimp industry, South Carolina's most economically important fishery, would cease to exist without the critical nursery function provided by intertidal salt marshes. Smooth cordgrass (Spartina alterniflora) is a keystone species in the high salinity marshes of the southeastern U.S., and its functioning is essential to the health and survival of salt marshes under rising sea levels. To better quantify and facilitate prediction of future salt marsh productivity, in May of 2017, we established a new integrated eddy covariance tower system to measure the net ecosystem exchange of carbon in a salt marsh in coastal South Carolina. The tower site is co-located with long-term, ongoing measurements as part of the North Inlet-Winyah Bay National Estuarine Research Reserve (NI-WB NERR). Current sampling conducted within the eddy flux footprint includes: annual measures of the vegetation community at the time of peak biomass; bi-monthly measures of sediment elevation at Sediment Elevation Tables (SETs) located at the upper and lower ends of the flux footprint; monthly sediment porewater salinity and nutrient (ammonium, orthophosphate) and sulfide concentrations; and biannual sediment elevation surveys by RTK-GPS. A suite of water quality measurements are made every 15 minutes in the main creek that floods the marsh platform in the flux footprint. Here we present our first six months of observations investigating the abiotic drivers of productivity on daily (intratidal) to monthly timescales
Elias, Edwin P.L.; Hansen, Jeff E.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.
2013-01-01
San Francisco Bay is one of the largest estuaries along the U.S. West Coast and is linked to the Pacific Ocean through the Golden Gate, a 100 m deep bedrock inlet. A coupled wave, flow and sediment transport model is used to quantify the sediment linkages between San Francisco Bay, the Golden Gate, and the adjacent open coast. Flow and sediment transport processes are investigated using an ensemble average of 24 climatologically derived wave cases and a 24.8 h representative tidal cycle. The model simulations show that within the inlet, flow and sediment transport is tidally dominated and driven by asymmetry of the ebb and flood tides. Peak ebb velocities exceed the peak flood velocities in the narrow Golden Gate channel as a result of flow convergence and acceleration. Persistent flow and sediment gyres at the headland tips are formed that limit sediment transfer from the ebb-tidal delta to the inlet and into the bay. The residual transport pattern in the inlet is dominated by a lateral segregation with a large ebb-dominant sediment transport (and flow) prevailing along the deeper north side of the Golden Gate channel, and smaller flood dominant transports along the shallow southern margin. The seaward edge of the ebb-tidal delta largely corresponds to the seaward extent of strong tidal flows. On the ebb-tidal delta, both waves and tidal forcing govern flow and sediment transport. Wave focusing by the ebb-tidal delta leads to strong patterns of sediment convergence and divergence along the adjacent Ocean Beach.
International Nuclear Information System (INIS)
Cherry, D.S.; Hassel, J.H. Van; Yeager, M.M.; Babendreier, J.E.; Currie, R.J.; Astin, L.E.; Lynde, S.R.
1995-01-01
Following the flooding of the Meigs number-sign 31 deep coal mine in Meigs County, Ohio, a proactive plan was developed to evaluate effects of initial dewatering, recovery, and development of a watershed enhancement plan. Approximately half of the 31-mile Leading Creek mainstem received coal mine discharge of high conductivity, low pH, high metals and total suspended solids loading. Most forms of aquatic life were depleted in the impacted areas of the creek. After three years since the incident, many forms of benthic macroinvertebrates and fish have returned to the creek, and sediments have been purged of metal loading by storm water events. The enhancement plan involves a reconnaissance of the creek and tributaries pinpointing areas of agricultural sedimentation and abandoned mined land (AML) influences in the lower half. Research activities involved sampling water and sediment in 10 stations of the creek and 17 major tributaries. The tributaries were addressed as point source discharges with water/sediment toxicity testing conducted. In-situ testing included growth impairment evaluation of Asian clams at 27 stations in the watershed. Several tributaries were intermittently toxic depending upon rainfall and the degree of AML input. Benthic macroinvertebrate assembles in most tributaries were stressed and comprised 0--3 taxa. Erosion/sedimentation loading was being addressed by hydrological modeling of the creek, land use management/habitat assessment, and data management by geographic information systems
Anticipated transport of Cs-137 from Steel Creek following L-Area restart
International Nuclear Information System (INIS)
Hayes, D.W.
1982-01-01
Heat exchanger cooling water, spent fuel storage basin effluents, and process water from P and L-Reactor Areas were discharged to Steel Creek beginning in 1954. Cs-137 was the most significant radionuclide discharged to the environs. Once the Cs-137 was discharged from P and L-Area reactors to Steel Creek, it became associated with silt and clay in the Steel Creek system. After its association with the silt and clay, the Cs-137 becomes part of the sediment transport process and undergoes continual deposition-resuspension in the stream system. This report discusses the expected fate and transport of Cs-137 currently present in the Steel Creek system after L-Reactor restart
Estuaries as filters: the role of tidal marshes in trace metal removal.
Directory of Open Access Journals (Sweden)
Johannes Teuchies
Full Text Available Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary.
Estuaries as Filters: The Role of Tidal Marshes in Trace Metal Removal
Teuchies, Johannes; Vandenbruwaene, Wouter; Carpentier, Roos; Bervoets, Lieven; Temmerman, Stijn; Wang, Chen; Maris, Tom; Cox, Tom J. S.; Van Braeckel, Alexander; Meire, Patrick
2013-01-01
Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary. PMID:23950927
Flow Convergence Caused by a Salinity Minimum in a Tidal Channel
Directory of Open Access Journals (Sweden)
John C. Warner
2006-12-01
Full Text Available Residence times of dissolved substances and sedimentation rates in tidal channels are affected by residual (tidally averaged circulation patterns. One influence on these circulation patterns is the longitudinal density gradient. In most estuaries the longitudinal density gradient typically maintains a constant direction. However, a junction of tidal channels can create a local reversal (change in sign of the density gradient. This can occur due to a difference in the phase of tidal currents in each channel. In San Francisco Bay, the phasing of the currents at the junction of Mare Island Strait and Carquinez Strait produces a local salinity minimum in Mare Island Strait. At the location of a local salinity minimum the longitudinal density gradient reverses direction. This paper presents four numerical models that were used to investigate the circulation caused by the salinity minimum: (1 A simple one-dimensional (1D finite difference model demonstrates that a local salinity minimum is advected into Mare Island Strait from the junction with Carquinez Strait during flood tide. (2 A three-dimensional (3D hydrodynamic finite element model is used to compute the tidally averaged circulation in a channel that contains a salinity minimum (a change in the sign of the longitudinal density gradient and compares that to a channel that contains a longitudinal density gradient in a constant direction. The tidally averaged circulation produced by the salinity minimum is characterized by converging flow at the bed and diverging flow at the surface, whereas the circulation produced by the constant direction gradient is characterized by converging flow at the bed and downstream surface currents. These velocity fields are used to drive both a particle tracking and a sediment transport model. (3 A particle tracking model demonstrates a 30 percent increase in the residence time of neutrally buoyant particles transported through the salinity minimum, as compared to
Baruch Institute for Marine and Coastal Sciences, Univ of South Carolina — Samples were taken from two estuarine tidal creek stations (designated BB and DD) in the North Inlet Estuary, SC. Two large cores, with a sediment surface area of...
Impact of vegetation die-off on spatial flow patterns over a tidal marsh
Temmerman, S.; Moonen, P.; Schoelynck, J.; Govers, G.; Bouma, T.J.
2012-01-01
Large-scale die-off of tidal marsh vegetation, caused by global change, is expected to change flow patterns over tidal wetlands, and hence to affect valuable wetland functions such as reduction of shoreline erosion, attenuation of storm surges, and sedimentation in response to sea level rise. This
Ijaz, Muhammad Wajid; Mahar, Rasool Bux; Siyal, Altaf Ali; Anjum, Muhammad Naveed
2018-01-01
Sea level rise (SLR) in response to looming climate change is being considered as a major impediment to coastal areas. Acute wave activities and tidal propagations of semi-diurnal to mixed type are impairing the morphology of the Indus Delta in Pakistan. In this study a synthetic approach has been adopted using multi sensor satellite and ground data in order to integrate the individual effect of topography, oceanic activities and vegetative canopy for deduction of a synergic impact over the morphology of the Indus Delta creeks system from 1972 to 2017. Geomorphologic anomalies in the planform of fourteen major creeks were explored. Spatiotemporal variations suggested that a substantial amount of the delta alluvium had been engulfed by the Arabian Sea. On average, the creeks located on the right side of the Indus River were relatively less wide (3.9 km) than those of on the left side (5.2 km). Zonal statistics calculated with topographic position index (TPI) enabled to understand the tide induced inundation extents. The mangrove canopy on the right side was found greater, which is why tidal basins on that side experienced less erosive activities. Thus, it could be maintained that the coastal sedimentary processes may be monitored effectively with the remotely sensed data and temporal pattern of changes can be quantified for future planning and mitigation of adverse effects.
Coarse sediment oil persistence laboratory studies and model
International Nuclear Information System (INIS)
Humphrey, B.; Harper, J.R.
1993-01-01
To gain understanding of the factors which affect the fate of stranded oil on coarse sediment beaches, a series of oil penetration and tidal flushing experiments was conducted in columns containing sediments of two grain sizes: granules and pebbles. The experiments included changing oil properties by weathering and by emulsification. Factors examined included permeability, effective porosity, and residual capacity of the sediment for oil. The laboratory data provided input to an oil persistence model for coarse sediment beaches, and the model was modified on the basis of the new data. The permeability measurements suggest that the permeability of pebble/granule mixtures is close to that of the smaller component. For low viscosity oils, the permeability in coarse sediments is rapid enough to match the fall and rise of tidal water. Effective porosity of the pebbles was ca 90% of the measured porosity, but for both the granules and a 50-50 pebble/granule mixture, the effective porosity was ca 75% of measured porosity. Results of tidal flushing simulation imply that flushing may be rapid but not efficient. The emulsion completely entered the sediment in the case of pebbles only. 2 refs., 6 figs., 3 tabs
International Nuclear Information System (INIS)
Costa, Eduardo S.; Grilo, Caroline F.; Wolff, George A.; Thompson, Anu; Figueira, Rubens Cesar Lopes; Neto, Renato Rodrigues
2015-01-01
Highlights: • Metals and hydrocarbons in estuary mouth showed indication of anthropogenic input. • Metals in estuary mouth were associated with petroleum-derivative hydrocarbons. • Metals were possibly associated with activities that use oil and its derivatives. • Copper was associated with domestic sewage. - Abstract: Although the Passagem Channel estuary, Espírito Santo State, Brazil, is located in an urbanized and industrialized region, it has a large mangrove system. Here we examined natural and anthropogenic inputs that may influence trace metal (Cd, Cr, Cu, Ni, Sc, Pb and Zn) and hydrocarbon (n-alkane and terpane) deposition in three sediment cores collected in the tidal flat zone of the estuary. The cores were also analyzed for carbonate, grain size and stable isotopic composition (δ 13 C org. and δ 15 N total ). Metal enrichment and its association to petroleum hydrocarbons in the surficial sediments of one of the cores, indicate crude oil and derivative inputs, possibly from small vessels and road run-off from local heavy automobile traffic. At the landward sites, the major contributions for metals and hydrocarbons are from natural sources, but in one case, Cu may have been enriched by domestic effluent inputs
Interstitial water chemistry and nutrients fluxes from tropical intertidal sediment
Digital Repository Service at National Institute of Oceanography (India)
Ram, A.; Zingde, M.D.
temporal changes in relation to their con- centrations in the overlying creek water. The high chlorinity creek water infiltrating in the bed after September, progres- sively pushed down the monsoonal low chlorinity water trapped in the sediment resulting....4-2.5%), the trend of decreasing con- centration with depth indicated some accumulation in the sediment over the years. The 1.0-2.5% Corgin core 2 commonly occurs in silty-clay sediment along the centra] west coast of India16 even in areas where there is no apparent...
Shellenbarger, Gregory; Wright, Scott A.; Schoellhamer, David H.
2013-01-01
The South Bay Salt Pond Restoration Project is overseeing the restoration of about 6000 ha of former commercial salt-evaporation ponds to tidal marsh and managed wetlands in the southern reach of San Francisco Bay (SFB). As a result of regional groundwater overdrafts prior to the 1970s, parts of the project area have subsided below sea-level and will require between 29 and 45 million m3 of sediment to raise the surface of the subsided areas to elevations appropriate for tidal marsh colonization and development. Therefore, a sufficient sediment supply to the far south SFB subembayment is a critical variable for achieving restoration goals. Although both major tributaries to far south SFB have been seasonally gaged for sediment since 2004, the sediment flux at the Dumbarton Narrows, the bayward boundary of far south SFB, has not been quantified until recently. Using daily suspended-sediment flux data from the gages on Guadalupe River and Coyote Creek, combined with continuous suspended-sediment flux data at Dumbarton Narrows, we computed a sediment budget for far south SFB during Water Years 2009–2011. A Monte Carlo approach was used to quantify the uncertainty of the flux estimates. The sediment flux past Dumbarton Narrows from the north dominates the input to the subembayment. However, environmental conditions in the spring can dramatically influence the direction of springtime flux, which appears to be a dominant influence on the net annual flux. It is estimated that up to several millennia may be required for natural tributary sediments to fill the accommodation space of the subsided former salt ponds, whereas supply from the rest of the bay could fill the space in several centuries. Uncertainty in the measurement of sediment flux is large, in part because small suspended-sediment concentration differences between flood and ebb tides can lead to large differences in total mass exchange. Using Monte Carlo simulations to estimate the random error associated with
Jones, Krista L.; Wallick, J. Rose; O'Connor, Jim E.; Keith, Mackenzie K.; Mangano, Joseph F.; Risley, John C.
2011-01-01
This preliminary assessment of (1) bed-material transport in the Hunter Creek basin, (2) historical changes in channel condition, and (3) supplementary data needed to inform permitting decisions regarding instream gravel extraction revealed the following: Along the lower 12.4 km (kilometers) of Hunter Creek from its confluence with the Little South Fork Hunter Creek to its mouth, the river has confined and unconfined segments and is predominately alluvial in its lowermost 11 km. This 12.4-km stretch of river can be divided into two geomorphically distinct study reaches based primarily on valley physiography. In the Upper Study Reach (river kilometer [RKM] 12.4-6), the active channel comprises a mixed bed of bedrock, boulders, and smaller grains. The stream is confined in the upper 1.4 km of the reach by a bedrock canyon and in the lower 2.4 km by its valley. In the Lower Study Reach (RKM 6-0), where the area of gravel bars historically was largest, the stream flows over bed material that is predominately alluvial sediments. The channel alternates between confined and unconfined segments. The primary human activities that likely have affected bed-material transport and the extent and area of gravel bars are (1) historical and ongoing aggregate extraction from gravel bars in the study area and (2) timber harvest and associated road construction throughout the basin. These anthropogenic activities likely have varying effects on sediment transport and deposition throughout the study area and over time. Although assessing the relative effects of these anthropogenic activities on sediment dynamics would be challenging, the Hunter Creek basin may serve as a case study for such an assessment because it is mostly free of other alterations to hydrologic and geomorphic processes such as flow regulation, dredging, and other navigation improvements that are common in many Oregon coastal basins. Several datasets are available that may support a more detailed physical assessment
Phase lag control of tidally reversing mega-ripple geometry and bed stress in tidal inlets
Traykovski, P.
2016-02-01
Recent observations in the Columbia River Mouth, New River Inlet, and Wasque Shoals have shown that tidally reversing mega-ripples are an ubiquitous bedform morphology in energetic tidal inlets. As the name implies, these bedforms reverse asymmetry and migration direction in each half tidal cycle. With wavelengths of 2 to 5 m and heights of 0.2 to 0.5 m, these bedforms are larger than current formed ripples, but smaller than dunes. Unlike dunes which have a depth dependent geometry, observations indicate the tidally reversing mega-ripples geometry is related to the time dependent tidal flow and independent of depth. Previous empirical relations for predicting the geometry of ripples or dunes do not successfully predict the geometry of these features. A time dependent geometric model was developed that accounts for the reversal of migration and asymmetry to successfully predict bedform geometry. The model requires sufficient sediment transport in each half tidal cycle to reverse the asymmetry before the bedforms begin to grow. Both the observations and model indicate that the complete reversal of asymmetry and development of a steep lee face occurs near or after maximum flow in each half tidal cycle. This phase lag in bedform response to tidal forcing also has important implications for bed stress in tidal inlets. Observations of frictional drag in the Columbia River mouth based on a tidal momentum balance of surface slope over 10 km regressed against quadratic near bed velocity show drag coefficients that fall off as CD U-1.4. Reynolds stress measurements performed using the dual ADV differencing technique show similar relations. The Reynolds stress measurements also show a dramatic asymmetry between accelerating flows and decelerating flows with a factor of 5 increase during deceleration. Pulse coherent Doppler profiles of near bed turbulence indicate that the turbulence is dominated by energetic fluctuations in separation zones downstream of steep lee faces. The
Review of sediment stabilisation techniques. Final report
Energy Technology Data Exchange (ETDEWEB)
1992-12-31
The best sites for tidal power schemes are found in estuaries with high tidal ranges which have complex ecosystems and include a wide and diverse range of habitats. If the tidal power is to be developed, therefore, it is important to determine the likely effect on the environment and any ameliorative measures which may be necessary. One possible change is likely to be the erosion of material from the bed or shoreline of the estuary, and possibly the adjacent coast. This is of particular concern if intertidal sandflats, mudflats and saltmarsh are affected, as these are important wildlife habitats. Moreover, largescale movement of sediments would be undesirable. Results of a desk study of methods of preventing the erosion of sediment deposits in or near an estuary in the conditions that may occur following the construction of a tidal power barrage are presented. (author).
Predicting long-term and short-term tidal flat morphodynamics using a dynamic equilibrium theory
Hu, Z.; Wang, Z.B.; Zitman, T.J.; Stive, M.J.F.; Bouma, T.J.
2015-01-01
Dynamic equilibrium theory is a fruitful concept, which we use to systematically explain the tidal flat morphodynamic response to tidal currents, wind waves, sediment supply, and other sedimentological drivers. This theory stems from a simple analytical model that derives the tide- or wave-dominated
Van Oyen, Tomas; Blondeaux, Paolo; Van den Eynde, Dries
2013-07-01
A site-by-site comparison between field observations and theoretical predictions of sediment sorting patterns along tidal sand waves is performed for ten locations in the North Sea. At each site, the observed grain size distribution along the bottom topography and the geometry of the bed forms is described in detail and the procedure used to obtain the model parameters is summarized. The model appears to accurately describe the wavelength of the observed sand waves for the majority of the locations; still providing a reliable estimate for the other sites. In addition, it is found that for seven out of the ten locations, the qualitative sorting process provided by the model agrees with the observed grain size distribution. A discussion of the site-by-site comparison is provided which, taking into account uncertainties in the field data, indicates that the model grasps the major part of the key processes controlling the phenomenon.
Simon, N.S.; Bricker, O.P.; Newell, W.; McCoy, J.; Morawe, R.
2005-01-01
This paper compares phosphorus (P) concentrations in sediments from two watersheds, one with, and one without, intensive animal agriculture. The watersheds are in the coastal plain of the Chesapeake Bay and have similar physiographic characteristics. Agriculture in the Pocomoke River, MD, watershed supplied 2.7 percent of all broiler chickens produced in the USA in 1997. Poultry litter is an abundant, local source of manure for crops. Broiler chickens are not produced in the Popes Creek, VA, watershed and poultry manure is, therefore, not a major source of fertilizer. The largest concentrations of P in sediment samples are found in floodplain and main-stem bottom sediment in both watersheds. Concentrations of total P and P extracted with 1N HCl are significantly larger in main-stem bottom sediments from the Pocomoke River than in main-stem bottom sediments from Popes Creek. Larger concentrations of P are associated with what are potentially redox sensitive iron oxyhydroxides in sediment samples from the Pocomoke River watershed than are associated with what are potentially redox sensitive iron oxyhydroxides in sediment samples from the Popes Creek watershed. Data for P and iron (Fe) concentrations in sediments from the Popes Creek watershed provide a numerical framework (baseline) with which to compare P and Fe concentrations in sediment from the Pocomoke River watershed. ?? Springer 2005.
Predominant Nearshore Sediment Dispersal Patterns in Manila Bay
Directory of Open Access Journals (Sweden)
Fernando Siringan
1997-12-01
Full Text Available Net nearshore sediment drift patterns in Manila Bay were determined by combining the coastal geomorphology depicted in 1 : 50,000scale topographic maps and Synthetic Aperture Radar (SAR images, with changes in shoreline position and predominant longshore current directions derived from the interaction of locally generated waves and bay morphology.Manila Bay is fringed by a variety of coastal subenvironments that reflect changing balances of fluvial, wave, and tidal processes. Along the northern coast, a broad tidal-river delta plain stretching from Bataan to Bulacan indicates the importance of tides, where the lateral extent of tidal influences is amplified by the very gentle coastal gradients. In contrast, along the Cavite coast sandy strandplains, spits, and wave-dominated deltas attest to the geomorphic importance of waves that enter the bay from the South China Sea.The estimates of net sediment drift derived from geomorphological, shoreline-change, and meteorological information are generally in good agreement. Sediment drift directions are predominantly to the northeast along Cavite, to the northwest along Manila and Bulacan, and to the north along Bataan. Wave refraction and eddy formation at the tip of the Cavite Spit cause southwestward sediment drift along the coast from Zapote to Kawit. Geomorphology indicates that onshore-offshore sediment transport is probably more important than alongshore transport along the coast fronting the tidal delta plain of northern Manila Bay. Disagreements between the geomorphic-derived and predicted net sediment drift directions may be due to interactions of wave-generated longshore currents with wind- and tide-generated currents.
Fey, David L.; Church, Stan E.; Finney, Christopher J.
1999-01-01
Metal-mining related wastes in the Boulder River basin study area in northern Jefferson County, Montana have been implicated in their detrimental effects on water quality with regard to acid-generation and toxic-metal solubilization. Flotation-mill tailings in the meadow below the Buckeye mine, hereafter referred to as the Buckeye mill-tailings site, have been identified as significant contributors to water quality degradation of Basin Creek, Montana. Basin Creek is one of three tributaries to the Boulder River in the study area; bed sediments and waters draining from the Buckeye mine have also been implicated. Geochemical analysis of 35 tailings cores and six bed-sediment samples was undertaken to determine the concentrations of Ag, As, Cd, Cu, Pb,and Zn present in these materials. These elements are environmentally significant, in that they can be toxic to fish and/or the invertebrate organisms that constitute their food. A suite of one-inch cores of dispersed flotation-mill tailings and underlying premining material was taken from a large, flat area north of Basin Creek near the site of the Buckeye mine. Thirty-five core samples were taken and divided into 204 subsamples. The samples were analyzed by ICP-AES (inductively coupled plasma-atomic emission spectroscopy) using a mixed-acid digestion. Results of the core analyses show that the elements listed above are present at moderate to very high concentrations (arsenic to 63,000 ppm, silver to 290 ppm, cadmium to 370 ppm, copper to 4,800 ppm, lead to 93,000 ppm, and zinc to 23,000 ppm). Volume calculations indicate that an estimated 8,400 metric tons of contaminated material are present at the site. Six bed-sediment samples were also subjected to the mixed-acid total digestion, and a warm (50°C) 2M HCl-1% H2O2 leach and analyzed by ICP-AES. Results indicate that bed sediments of Basin Creek are only slightly impacted by past mining above the Buckeye-Enterprise complex, moderately impacted at the upper (eastern
Arias, Michelle R.; Alpers, Charles N.; Marvin-DiPasquale, Mark C.; Fuller, Christopher C.; Agee, Jennifer L.; Sneed, Michelle; Morita, Andrew Y.; Salas, Antonia
2017-10-31
Cache Creek Settling Basin was constructed in 1937 to trap sediment from Cache Creek before delivery to the Yolo Bypass, a flood conveyance for the Sacramento River system that is tributary to the Sacramento–San Joaquin Delta. Sediment management options being considered by stakeholders in the Cache Creek Settling Basin include sediment excavation; however, that could expose sediments containing elevated mercury concentrations from historical mercury mining in the watershed. In cooperation with the California Department of Water Resources, the U.S. Geological Survey undertook sediment coring campaigns in 2011–12 (1) to describe lateral and vertical distributions of mercury concentrations in deposits of sediment in the Cache Creek Settling Basin and (2) to improve constraint of estimates of the rate of sediment deposition in the basin.Sediment cores were collected in the Cache Creek Settling Basin, Yolo County, California, during October 2011 at 10 locations and during August 2012 at 5 other locations. Total core depths ranged from approximately 4.6 to 13.7 meters (15 to 45 feet), with penetration to about 9.1 meters (30 feet) at most locations. Unsplit cores were logged for two geophysical parameters (gamma bulk density and magnetic susceptibility); then, selected cores were split lengthwise. One half of each core was then photographed and archived, and the other half was subsampled. Initial subsamples from the cores (20-centimeter composite samples from five predetermined depths in each profile) were analyzed for total mercury, methylmercury, total reduced sulfur, iron speciation, organic content (as the percentage of weight loss on ignition), and grain-size distribution. Detailed follow-up subsampling (3-centimeter intervals) was done at six locations along an east-west transect in the southern part of the Cache Creek Settling Basin and at one location in the northern part of the basin for analyses of total mercury; organic content; and cesium-137, which was
Gulf of Mexico Integrated Science - Tampa Bay Study - Characterization of Tidal Wetlands
McIvor, Carole
2005-01-01
Tidal wetlands in Tampa Bay, Florida, consist of mangrove forests and salt marshes. Wetlands buffer storm surges, provide fish and wildlife habitat, and enhance water quality through the removal of water-borne nutrients and contaminants. Substantial areas of both mangroves and salt marshes have been lost to agricultural, residential, and industrial development in this urban estuary. Wetlands researchers are characterizing the biological components of tidal wetlands and examining the physical factors such as salinity, tidal flushing, and sediment deposition that control the composition of tidal wetland habitats. Wetlands restoration is a priority of resource managers in Tampa Bay. Baseline studies such as these are needed for successful restoration planning and evaluation.
Scasso, Roberto A.; Cuitiño, José I.
2017-08-01
The late Miocene beds of the Puerto Madryn Formation (Provincia del Chubut, Argentina) are formed by shallow marine and estuarine sediments. The latter include several tidal-channel infills well exposed on the cliffy coast of the Peninsula Valdés. The Bahía Punta Fósil and Cerro Olazábal paleochannels are end members of these tidal channels and show a fining-upward infilling starting with intraformational channel lag conglomerates above deeply erosional surfaces interpreted as fluvial ravinement surfaces (the erosion surface formed in the purely fluvial or the fluvially dominated part of the estuary, where erosion is driven by fluvial processes). These are overlain and eventually truncated (and suppressed) by the tidal ravinement surface (TRS), in turn covered with high-energy, bioclastic conglomerates mostly formed in the "tidally dominated/fluvially influenced" part of an estuary. Above, large straight or arcuate point bars with alternatively sandy/muddy seasonal beds and varying trace and body fossil contents were deposited from the freshwater fluvially dominated to saline-water tidally dominated part of the estuary. The upper channel infill is formed by cross-bedded sands with mud drapes and seaward-directed paleocurrents, together with barren, volcaniclastic sandy to muddy heterolithic seasonal rhythmites, both deposited in the fluvially dominated part of the estuary. Volcanic ash driven by the rivers after large explosive volcanic eruptions on land resulted in sedimentation rates as high as 0.9 m per year, preserving (through burial) the morphology of tidal channels and TRSs. The channel deposits were formed in a tide-dominated, macrotidal to hypertidal open estuary with well-developed TRSs resulting from strong tidal currents deeply scouring into the transgressive filling of the channels and eventually cutting the fluvial ravinement surface. The TRSs extended upstream to the inner part of the estuary during long periods of low sedimentation rates
Vandenbruwaene, W.; Maris, T.; Cahoon, D.R.; Meire, P.; Temmerman, S.
2011-01-01
Along coasts and estuaries, formerly embanked land is increasingly restored into tidal marshes in order to re-establish valuable ecosystem services, such as buffering against flooding. Along the Scheldt estuary (Belgium), tidal marshes are restored on embanked land by allowing a controlled reduced tide (CRT) into a constructed basin, through a culvert in the embankment. In this way tidal water levels are significantly lowered (ca. 3 m) so that a CRT marsh can develop on formerly embanked land with a ca. 3 m lower elevation than the natural tidal marshes. In this study we compared the long-term change in elevation (ΔE) within a CRT marsh and adjacent natural tidal marsh. Over a period of 4 years, the observed spatio-temporal variations in ΔE rate were related to variations in inundation depth, and this relationship was not significantly different for the CRT marsh and natural tidal marsh. A model was developed to simulate the ΔE over the next century. (1) Under a scenario without mean high water level (MHWL) rise in the estuary, the model shows that the marsh elevation-ΔE feedback that is typical for a natural tidal marsh (i.e. rising marsh elevation results in decreasing inundation depth and therefore a decreasing increase in elevation) is absent in the basin of the CRT marsh. This is because tidal exchange of water volumes between the estuary and CRT marsh are independent from the CRT marsh elevation but dependent on the culvert dimensions. Thus the volume of water entering the CRT remains constant regardless of the marsh elevation. Consequently the CRT MHWL follows the increase in CRT surface elevation, resulting after 75 years in a 2–2.5 times larger elevation gain in the CRT marsh, and a faster reduction of spatial elevation differences. (2) Under a scenario of constant MHWL rise (historical rate of 1.5 cm a-1), the equilibrium elevation (relative to MHWL) is 0.13 m lower in the CRT marsh and is reached almost 2 times faster. (3) Under a scenario of
Selected elements and organic chemicals in streambed sediment in the Salem area, Oregon, 1999
Tanner, Dwight Q.
2002-09-13
Analysis of streambed sediments in the Salem, Oregon, area showed anomalously large concentrations of some elements and organic chemicals, indicating contamination from anthropogenic and/or geologic sources. The streambed sediment sample from Clark Creek, an urban basin, had large concentrations of polycyclic aromatic hyrdocarbons (PAHs), organochlorines, cadmium, lead, and zinc. The sample from the East Fork of Pringle Creek, which is a mostly urban basin, had the highest concentrations of DDD, DDE, and DDT compounds. Aldrin was detected in streambed sediment at only one site, the East Fork of Pringle Creek. Ten of the 14 sites sampled had exceedances of the sediment quality guidelines of the Canadian Council of Ministers of the Environment (CCME), and 8 sites had exceedances of guidelines from the Puget Sound Dredged Disposal Analysis (PSDDA) Program.
Recovery and enhancement plan development for the Leading Creek watershed, Meigs County, Ohio
International Nuclear Information System (INIS)
Currie, R.J.; Cherry, D.S.; Latimer, H.A.; Babendreier, J.E.; Van Hassel, J.H.
1998-01-01
Following the flooding of the Meigs No. 31 coal mine in Meigs County, Ohio, a proactive plan was developed to evaluate initial dewatering effects, recovery and development of a watershed enhancement plan. Approximately half of the 31-mile Leading Creek mainstem received ∼one billion gallons of coal mine discharge, including sludge and slurry. Damage to the stream system resulted from high conductivity (∼6,000 micromhos/cm), low pH (2.5--3.5), high metals (aluminum, cadmium, copper, iron and iron floc, lead, manganese, nickel and zinc) and total suspended solids. Most forms of aquatic life were depleted in the impacted areas. Four years after the incident, many forms of benthic macroinvertebrates and fish have recovered in the creek, with sediments purged of metals by stormwater events. The enhancement plan involves a reconnaissance of the creek and tributaries pinpointing areas of agricultural sedimentation and abandoned minedland discharges (AMD). Seventeen tributary and ten mainstem stations were addressed as point source discharges with water/sediment toxicity and in-situ testing of Asian clams. One-third of the stations were intermittently toxic from rainfall runoff and the degree of AMD input. Benthic macroinvertebrates in many tributaries were stressed and comprised 1--5 taxa. Erosion/sedimentation was addressed by the USEPA 1-Dimensional Hydrologic Simulation Program Fortran (HSPF) model, as well as incorporating land use management/habitat assessment, and data management by Geographical Information Systems
Morin, R.H.; Sorey, M.L.; Jacobson, R.D.
1993-01-01
Bayboro Harbor and the Port of St. Petersburg, Florida, form a manmade basin adjacent to Tampa Bay that may supply turbid water to the bay and subsequently affect light penetration in water in the bay. To address concerns about the nature and extent of this potential problem, resuspension of bottom sediments, sedimentation, and tributary storm discharge in the basin were studied. Study results indicated that tidal currents, wind waves, and seiche motions do not resuspend bottom sediments. The maneuvering of a cruise ship in the port resuspended bottom sediments, but these sediments settled within 2 hours. Tidal currents and wave action were not large enough o prevent the resuspended sediments from settling in the basin. Analysis of bathymetric surveys of the port made in 1981, 1986, 1987, and 1989 indicates that the cruise ship has deepened the port along its route and that the displaced sediment has been deposited elsewhere within the port. The storm discharge from two tributaries and the effect of tributary storm runoff on the water quality of the harbor were studied during a storm on November 9, 1989. Booker Creek, which drains an urban watershed, was stratified with a thin layer of turbid freshwater flowing into the harbor over a layer of less turbid saltwater. Salt Creek, which primarily drains Lake Maggiore, was only partially stratified and was less turbid. The turbid water from the creeks increased the turbidity only slightly in the harbor, probably because of mixing with less turbid water and particle settling. Thus, the basin provides mixing and settling, which diminish and eliminate the potentially adverse effect on Tampa Bay from tributary storm runoff and large vessel traffic in the basin.
On effects produced by tidal power plants upon environmental conditions in adjacent sea areas
International Nuclear Information System (INIS)
Nekrasov, A.V.; Romanenkov, D.A.
1997-01-01
Consideration is given to the change in natural (oceanographic) environmental conditions due to the transformation of the tidal oscillations structure resulting from erection and operation of tidal power plants (TPP). The relevant transformation of tidal movements encompasses practically all its main characteristics: amplitudes, phases and spectral composition of sea level oscillations, as well as the similar parameters of tidal currents and also the intensity and positioning of extremes zones. The changes in positioning and width of the inter-tidal zone, the inter-tidal zone regime, mutual arrangement of mixed, stratified and transient frontal zones, transportation of suspended matter and bottom sedimentation, owing to residual tidal currents, sea ice characteristics, air these changes can be estimated on the basis of mathematical predictive modelling of tidal characteristics transformed by a contemplated tidal power plant. Some results are presented for the Russian large-scale TPP projects in the White and Okhotsk seas. (author)
Susperregui, A.
2010-12-01
The Rance basin (France) offers potential to make a full-scale assessment of the environmental impact of a tidal power station after 50 years of operation. Consequences on biology, hydrodynamics and sedimentology were observed and nowadays, some of these changes are still acting on the natural system. The tidal dynamic was completely artificialised by the dam construction. The two main consequences are the reduction of exundation area and the extension of slack duration. Sedimentary dynamic depending on hydrodynamics conditions, changes in sediment distribution were also observed. Before the tidal power station construction, sands lined the gravel bed channel, recovered the bottom and formed beaches and banks. Coves and the upstream part of the estuary were dominated by a fine sedimentation, forming mudflats in a classical configuration slikke/schorre. Nowadays, mudflats extended to the center of the basin and all coves are occupied. The important inertia induced by the slack extension caused a slowing down on currents velocities, making easier the fine suspension deposit. The siltation is most important upstream, were the turbidity maximum was shifted, generating problems for navigation and banks access. A solution of sediment management was envisaged from 2001, by the digging of a sediments trap of 91 000 m3, near the Châtelier Lock. Sedimentation monitoring in this trap shows an intense filling over the first two years of functioning, then a slowing down leading to a complete filling from 2005. This trap also showed a beneficial interest on the sedimentation rates of the mudflats closed to it, which decreased. To understand how fine sediment is eroded and transported into this maritime area, an optical backscatter sensor was installed 1.5 km upstream of the tidal power station. During spring tides, the tidal power station functions in a “double-acting” cycle. This particular working leads to an important increase of turbidity during the artificial tidal
International Nuclear Information System (INIS)
1976-01-01
The Lawrence Livermore Laboratory (LLL) is conducting a hydrogeochemical and stream-sediment survey in the seven western states as part of ERDA's National Uranium Resources Evaluation (NURE) Program. The objective of this survey is to develop a geochemical data base for use by the private sector to locate regions of anomalous uranium content. Prior to wide area coverage, several pilot studies are being undertaken to develop and evaluate sampling and analytical techniques. The second through fifth of these studies were conducted in four playa basins in Nevada, selected to represent different regional geology and uranium occurrence. This study in the Smoke Creek Desert Basin, characterizes igneous surface geology with known uranium occurrences. The Smoke Creek Desert Basin is the largest of the four playa basins and contains an areaof about 2700 square kilometers (1003 square miles). The basin is bordered on the east by the Fox Hills and on the north and east by the Granite Ranges which are characterized by granite, pegmatites, and Tertiary rocks very similar to the lithology of the Winnemucca Basin boundary ranges (study UCID-16911-P-2). On the west the Desert is bordered by an area of extensive basalt flow. There is no known uranium occurrence in the area, and metallization of any kind is scarce. This study is applicable to the western igneous portion of the Basin and Range Province which includes southeastern Oregon, western Nevada, and southeastern California. This report contains only analytical data and sample locations
Literature Review of Unconsolidated Sediment in San Francisco Bay and Nearby Pacific Ocean Coast
Directory of Open Access Journals (Sweden)
Barry R. Keller
2009-09-01
Full Text Available A review of the geologic literature regarding sedimentation in the San Francisco Bay estuarine system shows that the main part of the bay occupies a structural tectonic depression that developed in Pleistocene time. Eastern parts, including San Pablo Bay and Suisun Bay, have had sedimentation throughout late Mesozoic and Tertiary. Carquinez Strait and the Golden Gate may represent antecedent stream erosion. Sedimentation has included estuarine, alluvial, and eolian deposition. The ages of estuarine deposition includes the modern high sea level stand and earlier Pleistocene interglacial periods. Sediment sources can be generally divided into the Coast Ranges, particularly the Franciscan Complex, and “Sierran.” Much of the estuarine system is floored by very fine sediment, with local areas of sand floor. Near the Golden Gate, sediment size decreases in both directions away from the deep channel. Bedforms include sand waves (submarine dunes, flat beds, and rock and boulders. These are interpreted in terms of dominant transport directions. Near the Golden Gate is an ebb-tidal delta on the outside (including San Francisco bar and a flood-tidal delta on the inside (parts of Central Bay. The large tidal prism causes strong tidal currents, which in the upper part of the estuary are normally much stronger than river currents, except during large floods. Cultural influences have altered conditions, including hydraulic mining debris, blasting of rocks, dredging of navigation channels, filling of the bay, and commercial sand mining. Many of these have served to decrease the tidal prism, correspondingly decreasing the strength of tidal currents.
The origin of neap-spring tidal cycles
Kvale, E.P.
2006-01-01
The origin of oceanic tides is a basic concept taught in most introductory college-level sedimentology/geology, oceanography, and astronomy courses. Tides are typically explained in the context of the equilibrium tidal theory model. Yet this model does not take into account real tides in many parts of the world. Not only does the equilibrium tidal model fail to explicate amphidromic circulation, it also does not explain diurnal tides in low latitude positions. It likewise fails to explain the existence of tide-dominated areas where neap-spring cycles are synchronized with the 27.32-day orbital cycle of the Moon (tropical month), rather than with the more familiar 29.52-day cycle of lunar phases (synodic month). Both types of neap-spring cycles can be recognized in the rock record. A complete explanation of the origin of tides should include a discussion of dynamic tidal theory. In the dynamic tidal model, tides resulting from the motions of the Moon in its orbit around the Earth and the Earth in its orbit around the Sun are modeled as products of the combined effects of a series of phantom satellites. The movement of each of these satellites, relative to the Earth's equator, creates its own tidal wave that moves around an amphidromic point. Each of these waves is referred to as a tidal constituent. The geometries of the ocean basins determine which of these constituents are amplified. Thus, the tide-raising potential for any locality on Earth can be conceptualized as the result of a series of tidal constituents specific to that region. A better understanding of tidal cycles opens up remarkable opportunities for research on tidal deposits with implications for, among other things, a more complete understanding of the tidal dynamics responsible for sediment transport and deposition, changes in Earth-Moon distance through time, and the possible influences tidal cycles may exert on organisms. ?? 2006 Elsevier B.V. All rights reserved.
Foster, Guy M.; Lee, Casey J.; Ziegler, Andrew C.
2012-01-01
The U.S. Geological Survey, in cooperation with the Kansas Water Office, investigated sediment transport to and from three small impoundments (average surface area of 0.1 to 0.8 square miles) in northeast Kansas during March 2009 through September 2011. Streamgages and continuous turbidity sensors were operated upstream and downstream from Atchison County, Banner Creek, and Centralia Lakes to study the effect of varied watershed characteristics and agricultural practices on sediment transport in small watersheds in northeast Kansas. Atchison County Lake is located in a predominantly agricultural basin of row crops, with wide riparian buffers along streams, a substantial amount of tile drainage, and numerous small impoundments (less than 0.05 square miles; hereafter referred to as “ponds”). Banner Creek Lake is a predominantly grassland basin with numerous small ponds located in the watershed, and wide riparian buffers along streams. Centralia Lake is a predominantly agricultural basin of row crops with few ponds, few riparian buffers along streams, and minimal tile drainage. Upstream from Atchison County, Banner Creek, and Centralia Lakes 24, 38, and 32 percent, respectively, of the total load was transported during less than 0.1 percent (approximately 0.9 days) of the time. Despite less streamflow in 2011, larger sediment loads during that year indicate that not all storm events transport the same amount of sediment; larger, extreme storms during the spring may transport much larger sediment loads in small Kansas watersheds. Annual sediment yields were 360, 400, and 970 tons per square mile per year at Atchison County, Banner, and Centralia Lake watersheds, respectively, which were less than estimated yields for this area of Kansas (between 2,000 and 5,000 tons per square mile per year). Although Centralia and Atchison County Lakes had similar percentages of agricultural land use, mean annual sediment yields upstream from Centralia Lake were about 2.7 times
Will Restored Tidal Marshes Be Sustainable?
Directory of Open Access Journals (Sweden)
Michelle Orr
2003-10-01
Full Text Available We assess whether or not restored marshes in the San Francisco Estuary are expected to be sustainable in light of future landscape scale geomorphic processes given typical restored marsh conditions. Our assessment is based on a review of the literature, appraisal of monitoring data for restored marshes, and application of vertical accretion modeling of organic and inorganic sedimentation. Vertical accretion modeling suggests that salt marshes in San Pablo Bay will be sustainable for moderate relative sea level rise (3 to 5 mm yr-1 and average sediment supply (c. 100 mg L-1. Accelerated relative sea level rise (above 6 mm yr-1 and/or reduced sediment supply (50 mg L-1 will cause lowering of the marsh surface relative to the tide range and may cause shifts from high to low marsh vegetation by the year 2100. Widespread conversion of marsh to mudflat-"ecological drowning"-is not expected within this time frame. Marshes restored at lower elevations necessary to aid the natural development of channel systems (c. 0.5 m below mean higher high water are predicted to accrete to high marsh elevations by the year 2100 for moderate relative sea level rise and sediment supply conditions. Existing rates of sediment accretion in restored fresh water tidal marshes of the Delta of greater than 9 mm yr-1 and slightly lower drowning elevations suggest that these marshes will be resilient against relatively high rates of sea level rise. Because of higher rates of organic production, fresh water marshes are expected to be less sensitive to reduced sediment availability than salt marshes. The ultimate long-term threat to the sustainability of tidal marshes is the interruption of coastal rollover-the process by which landward marsh expansion in response to sea level rise compensates for shoreline erosion. Bay front development now prevents most landward marsh expansion, while shoreline erosion is expected to accelerate as sea level rises.
Banks, William S.L.; Johnson, Carole D.
2011-01-01
The U.S. Geological Survey collected geophysical data in Deep Creek Lake in Garrett County, Maryland, between September 17 through October 4, 2007 to assist the Maryland Department of Natural Resources to better manage resources of the Lake. The objectives of the geophysical surveys were to provide estimates of sediment thickness in shallow areas around the Lake and to test the usefulness of three geophysical methods in this setting. Ground-penetrating radar (GPR), continuous seismic-reflection profiling (CSP), and continuous resistivity profiling (CRP) were attempted. Nearly 90 miles of GPR radar data and over 70 miles of CSP data were collected throughout the study area. During field deployment and testing, CRP was determined not to be practical and was not used on a large scale. Sediment accumulation generally could be observed in the radar profiles in the shallow coves. In some seismic profiles, a thin layer of sediment could be observed at the water bottom. The radar profiles appeared to be better than the seismic profiles for the determination of sediment thickness. Although only selected data profiles were processed, all data were archived for future interpretation.
Smith, Loren M.; Euliss, Ned H. "Chip"
2010-01-01
In the wetland science field, sediment deposition is often thought of as being beneficial especially when one thinks of coastal estuarine systems. For example, sediments deposited from streams and rivers are necessary to naturally build and maintain tidal marshes. These sediments come from eroded upland soils in the interior of the continent. When these sediments are diverted from natural coastal deposition areas, such as occurs from river channelization, we lose marshes through subsidence as is happening throughout coastal Louisiana. However, the value of eroded soils is all a matter of hydrogeomorphic perspective.
International Nuclear Information System (INIS)
Kershaw, P.J.; Denoon, D.C.; Woodhead, D.S.
1999-01-01
The distribution of plutonium and americium in the sub-tidal sediments of the Irish Sea is described following major surveys in 1978, 1983, 1988 and 1995. Concentrations in surface sediments have declined near the source at Sellafield since 1988. Time-series of inter-tidal surface sediment concentrations are presented from 1977 onwards, revealing the importance of sediment reworking and transport in controlling the evolution of the environmental signal. The surface and near-surface sediments, in the eastern Irish Sea 'mud-patch', are generally well mixed with respect to Pu (α) and 241 Am distributions but show increasing variability with depth - up to 4 orders of magnitude in concentration. The inventories of 239,240 Pu and 241 Am in the sub-tidal sediments have been estimated and compared with the reported decay-corrected discharges. These amounted to 360 and 545 TBq respectively, in 1995, about 60% of the total decay-corrected discharge. Part of the unaccounted fraction may be due to unrepresentative sampling of the seabed. It is speculated that some tens of TBq of plutonium and 241 Am reside undetected in the large volumes of coarse-grained, sub-tidal and inter-tidal sediment which characterise much of the Irish Sea. This has been due to the inability of the available corers to penetrate to the base of contamination in these mobile sediments. Further observations are needed to verify and quantify the missing amount. A budget of plutonium-α and 241 Am has been estimated based on published observations in the three main compartments: water column, sub-tidal and inter-tidal sediments. This amounts to 460-540 TBq and 575-586 TBq respectively, or 64-75% and 60-61%, of the decay-corrected reported discharge. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)
Zn, Pb, Cr and Cd concentrations in fish, water and sediment from ...
African Journals Online (AJOL)
ADOWIE PERE
Zn, Pb, Cr and Cd concentrations in fish, water and sediment from the Azuabie Creek,. Port Harcourt. ... Heavy metal contamination in the aquatic ... Azuabie Creek and the associated water ..... Public in Tianjin, China via Consumption of.
Lee, Yoon-Kyung; Choi, Jong-Kuk; Ryu, Joo-Hyung; Eom, Jinah
2014-05-01
Tidal flats are valuable ecosystem by a productive flora and fauna which support large populations of birds, form nursery and feeding areas for coastal fisheries, provide intrinsic values such as aesthetics and education (Costanza et al., 1997; Goodwin et al., 2001). The half of the world's coastal wetlands will submerge during this century in response to sea level rise although salt marsh has a capacity to adjust to sea level rise change. However, tidal flats have been changed because of several coastal construction projects that had not been considered sustainable over the last 30 years in Korean Peninsula. The total area of tidal flats decreased from approximately 2,800 km2 in 1990 to 2,393 km2 in 2005 due to the land reclamations and dredging in South Korea. Many researchers investigated topography, sedimentation changes and local hydrodynamics for this area in the early 1990s. However, they are limited to the temporal and spatial scale because field surveys in the tidal flats are restricted due to the difficulties in accessing. The aim of this study was to examine environmental change in tidal flat in a large scale for long-term based on the remotely sensed data as well as in situ measurements. This study focused on the tidal flat that not only had been affected by reclamations on a large scale such as Ganghwa and Saemangeum but also had been indirectly affected by reclamations such as Hwang-do and Gomso-bay. In this study, changes in morphology and sedimentary facies in tidal flats were estimated. Digital elevation models (DEMs) in early 2000 and 2010 were generated based on the Landsat TM/ETM+ images using a waterline method. Morphological change was estimated based on the differences of DEMs and sedimentary facies was investigated based on the calculation of image-derived PCA coefficient. Results of the morphological change in tidal flats interestingly showed that large amount of areas had been deposited whereas the other areas were eroded. Area with
Water and suspended sediment dynamics in the Sungai Selangor estuary
International Nuclear Information System (INIS)
Abdul Kadir Ishak; Kamarudin Samuding; Nazrul Hizam Yusoff
2000-01-01
Observations of salinity, temperature, suspended sediment concentration (SSC) and tidal current velocity were made in the lower and along the longitudinal axis sungai Selangor estuary over near-spring cycles. The variations of these parameters at the measurement stations and along the channel are presented to illustrate the water and sediment dynamics in the estuary. The results shows that the Sungai Selangor estuary changes from a partially-mixed type during neaps to a well-mixed one during springs. promoted by stronger tidal energy during the higher tidal ranges. The strong neap density stratification is also promoted by the high river discharges during the measurement period maximum concentration of suspended sediment 2000 mg,'/) occurs during maximum current velocities both during flood and ebb. The maximum salinity was achieved during high water slack but the salt water was totally flushed out of estuary during low water springs. The longitudinal axis measurement indicates that a partially-developed zone of turbidity maximum with a sediment concentration over 1000 mg/l was observed at the limit of salt water intrusion in salinity range less than 1 ppt. Tidal pumping as oppose to the estuarine circulation is the more dominant factor in the maximum formation as the salt water is totally excluded at low water. (author)
Jamieson, E. C.; Rennie, C. D.; Townsend, R. D.
2009-05-01
towards the centre of the channel, away from the outside bank. Sawmill Creek has the added complexity of having predominately clay bed and banks. The erosional behaviour of cohesive sediments such as clay is difficult to model correctly, due to the complex site-specific physio- chemical properties of clay particles. Following the construction of the proposed barbs at our field test site this summer (2009), and data collection the following spring and summer, we hope to advance the current knowledge of cohesive sediment transport processes in a complicated three-dimensional turbulent flow field. For the present modelling effort, erodibility of the consolidated clay bed and bank material was estimated based on establishing an entrainment threshold at near-bankfull conditions. The focus of this research is on (i) the unique site conditions and environmental protection requirements, (ii) design methodology, and (iii) results of the numerical simulation. The three-dimensional numerical model was capable of reproducing the expected distribution of secondary flow in a channel bend, the unique three- dimensional flow field resulting from a series of submerged structures and the associated patterns of soil erosion and deposition. The numerical modelling also demonstrated to be a useful tool for optimizing barb design for stream bank protection at the proposed field test site. Modelling results confirmed that in the vicinity of the barbs, the addition of the proposed barb layout achieved substantial reduction in erosion (up to 98 %), bed shear stress (up to 59 %) and streamwise velocity (up to 51 %).
Chanat, Jeffrey G.; Miller, Cherie V.; Bell, Joseph M.; Majedi, Brenda Feit; Brower, David P.
2013-01-01
Discrete samples and continuous (15-minute interval) water-quality data were collected at Mattawoman Creek (U.S. Geological Survey station number 01658000) from October 2000 through January 2011, in cooperation with the Charles County (Maryland) Department of Planning and Growth Management, the Maryland Department of the Environment, and the Maryland Geological Survey. Mattawoman Creek is a fourth-order Maryland tributary to the tidal freshwater Potomac River; the creek’s watershed is experiencing development pressure due to its proximity to Washington, D.C. Data were analyzed for the purpose of describing ambient water quality, identifying potential contaminant sources, and quantifying nutrient and sediment loads to the tidal freshwater Mattawoman estuary. Continuous data, collected at 15-minute intervals, included discharge, derived from stage measurements made using a pressure transducer, as well as water temperature, pH, specific conductance, dissolved oxygen, and turbidity, all measured using a water-quality sonde. In addition to the continuous data, a total of 360 discrete water-quality samples, representative of monthly low-flow and targeted storm conditions, were analyzed for suspended sediment and nutrients. Continuous observations gathered by a second water-quality sonde, which was temporarily deployed in 2011 for quality-control purposes, indicated substantial lateral water-quality gradients due to inflow from a nearby tributary, representing about 10 percent of the total gaged area upstream of the sampling location. These lateral gradients introduced a time-varying bias into both the continuous and discrete data, resulting in observations that were at some times representative of water-quality conditions in the main channel and at other times biased towards conditions in the tributary. Despite this limitation, both the continuous and discrete data provided insight into the watershed-scale factors that influence water quality in Mattawoman Creek
Smith, D. Charlie
2016-12-14
Lead and zinc were mined in the Tri-State Mining District (TSMD) of southwest Missouri, northeast Oklahoma, and southeast Kansas for more than 100 years. The effects of mining on the landscape are still evident, nearly 50 years after the last mine ceased operation. The legacies of mining are the mine waste and discharge of groundwater from underground mines. The mine-waste piles and underground mines are continuous sources of trace metals (primarily lead, zinc, and cadmium) to the streams that drain the TSMD. Many previous studies characterized the horizontal extent of mine-waste contamination in streams but little information exists on the depth of mine-waste contamination in these streams. Characterizing the vertical extent of contamination is difficult because of the large amount of coarse-grained material, ranging from coarse gravel to boulders, within channel sediment. The U.S. Geological Survey, in cooperation with U.S. Fish and Wildlife service, collected channel-sediment samples at depth for subsequent analyses that would allow attainment of the following goals: (1) determination of the relation between concentration and depth for lead, zinc and cadmium in channel sediments and flood-plain sediments, and (2) determination of the volume of gravel-bar sediment from the surface to the maximum depth with concentrations of these metals that exceeded sediment-quality guidelines. For the purpose of this report, volume of gravel-bar sediment is considered to be distributed in two forms, gravel bars and the wetted channel, and this study focused on gravel bars. Concentrations of lead, zinc, and cadmium in samples were compared to the consensus probable effects concentration (CPEC) and Tri-State Mining District specific probable effects concentration (TPEC) sediment-quality guidelines.During the study, more than 700 sediment samples were collected from borings at multiple sites, including gravel bars and flood plains, along Center Creek, Turkey Creek, Shoal Creek
Temporal variation of aerobic methane oxidation over a tidal cycle in a wetland of northern Taiwan.
Lee, T. Y.; Wang, P. L.; Lin, L. H.
2017-12-01
Aerobic methanotrophy plays an important role in controlling methane emitted from wetlands. However, the activity of aerobic methanotrophy regulated by temporal fluctuation of oxygen and methane supply in tidal wetlands is not well known. This study aims to examine the dynamics of methane fluxes and potential aerobic methane consumption rates in a tidal wetland of northern Taiwan, where the variation of environmental characteristics, such as sulfate and methane concentration in pore water has been demonstrated during a tidal cycle. Two field campaigns were carried out in December of 2016 and March of 2017. Fluxes of methane emission, methane concentrations in surface sediments and oxygen profiles were measured at different tidal phases. Besides, batch incubations were conducted on surface sediments in order to quantify potential microbial methane consumption rates and to derive the kinetic parameters for aerobic methanotrophy. Our results demonstrated temporal changes of the surface methane concentration and the methane emission flux during a tidal cycle, while the oxygen flux into the sediment was kept at a similar magnitude. The methane flux was low when the surface was exposed for both shortest and longest periods of time. The potential aerobic methane oxidation rate was high for sample collected from the surface sediments exposed the longest. No correlation could be found between the potential aerobic methane oxidation rate and either the oxygen downward flux or methane emission flux. The decoupled relationships between these observed rates and fluxes suggest that, rather than aerobic methanotrophy, heterotrophic respirations exert a profound control on oxygen flux, and the methane emission is not only been affected by methane consumption but also methane production at depths. The maximum potential rate and the half saturation concentration determined from the batch incubations were high for the surface sediments collected in low tide, suggesting that aerobic
Miller, Todd S.
2009-01-01
In 2002, the U.S. Geological Survey, in cooperation with the Town of Caroline and Tompkins County Planning Department, began a study of the valley-fill aquifer system in upper Sixmile Creek and headwaters of West Branch Owego Creek valleys in the Town of Caroline, NY. The purpose of the study is to provide geohydrologic data to county and town planners as they develop a strategy to manage and protect their water resources. The first aquifer reach investigated in this series is in the Town of Caroline and includes the upper Sixmile Creek valley and part of West Branch Owego Creek valley. The portions of the valley-fill aquifer system that are comprised of saturated coarse-grained sediments including medium to coarse sand and sandy gravel form the major aquifers. Confined sand and gravel units form the major aquifers in the western and central portions of the upper Sixmile Creek valley, and an unconfined sand and gravel unit forms the major aquifer in the eastern portion of the upper Sixmile Creek valley and in the headwaters of the West Branch Owego Creek valley. The valley-fill deposits are thinnest near the edges of the valley where they pinch out along the till-mantled bedrock valley walls. The thickness of the valley fill in the deepest part of the valley, at the western end of the study area, is about 100 feet (ft); the thickness is greater than 165 ft on top of the Valley Heads Moraine in the central part of the valley. An estimated 750 people live over and rely on groundwater from the valley-fill aquifers in upper Sixmile Creek and West Branch Owego Creek valleys. Most groundwater withdrawn from the valley-fill aquifers is pumped from wells with open-ended 6-inch diameter casings; the remaining withdrawals are from shallow dug wells or cisterns that collect groundwater that discharges to springs (especially in the Brooktondale area). The valley-fill aquifers are the sources of water for about 200 households, several apartment complexes, two mobile home parks
Yona, D.; Febriana, R.; Handayani, M.
2018-04-01
This study attempted to investigate different concentration of lead (Pb) dan cadmium (Cd) in the water and sediment during spring and neap tidal periods in the Popoh Bay, Indonesia. Water and sediment samples were taken during spring and neap tides from eight sampling stations in the study area. The result shows higher concentration of Pb than the concentration of Cd in both spring and neap tides due to higher input of Pb from the oil pollution by boat and fisheries activities. Pb concentrations were doubled during neap tide in both water and sediments with the value of 0.51 and 0.28 ml/L in the water during neap and spring tide, respectively; and 0.27 ppm and 0.16 mg/kg in the sediment during neap and spring tide, respectively. On the other hand, Cd concentrations in the water were found in almost similar values between spring and neap tide (0.159 and 0.165 ml/L in spring tide and neap tide, respectively), but in the sediment, the concentration was a little higher during spring tide (0.09 and 0.05 mg/kg during spring and neap tide, respectively). This study shows that water movement during spring and neap tides has significant effect on the distribution of heavy metals.
McPherson, Ann K.; Abrahamsen, Thomas A.; Journey, Celeste A.
2002-01-01
The U.S. Geological Survey conducted a 16-month investigation of water quality, aquatic-community structure, bed sediment, and fish tissue in Village and Valley Creeks, two urban streams that drain areas of highly intensive residential, commercial, and industrial land use in Birmingham, Alabama. Water-quality data were collected between February 2000 and March 2001 at four sites on Village Creek, three sites on Valley Creek, and at two reference sites near Birmingham?Fivemile Creek and Little Cahaba River, both of which drain less-urbanized areas. Stream samples were analyzed for major ions, nutrients, fecal bacteria, trace and major elements, pesticides, and selected organic constituents. Bed-sediment and fish-tissue samples were analyzed for trace and major elements, pesticides, polychlorinated biphenyls, and additional organic compounds. Aquatic-community structure was evaluated by conducting one survey of the fish community and in-stream habitat and two surveys of the benthic-invertebrate community. Bed-sediment and fish-tissue samples, benthic-invertebrates, and habitat data were collected between June 2000 and October 2000 at six of the nine water-quality sites; fish communities were evaluated in April and May 2001 at the six sites where habitat and benthic-invertebrate data were collected. The occurrence and distribution of chemical constituents in the water column and bed sediment provided an initial assessment of water quality in the streams. The structure of the aquatic communities, the physical condition of the fish, and the chemical analyses of fish tissue provided an indication of the cumulative effects of water quality on the aquatic biota. Water chemistry was similar at all sites, characterized by strong calcium-bicarbonate component and magnesium components. Median concentrations of total nitrogen and total phosphorus were highest at the headwaters of Valley Creek and lowest at the reference site on Fivemile Creek. In Village Creek, median
Directory of Open Access Journals (Sweden)
James Werllen de Jesus Azevedo
2016-03-01
Full Text Available Abstract In recent decades, intense human intervention in the coastal zone has given rise to severe siltation and erosion problems. This scenario is located the São Luís tidal inlet, formed by the mouths of the Anil and Bacanga rivers which due to various kinds of interference have been changing their sediment transport and deposition processes. With these changes in mind, this study sought to evaluate the evolution of the siltation and sedimentation rates in this area, as well as the main anthropogenic influences associated with this process. The methodology consisted in verifying the morphological evolution on the basis of the scanning and vectorization of nautical charts of 1947 and 1966, bathymetric surveys conducted in 2006, and aerial photos dating from 2011. The results show a silting up process coincident with interventions that occurred in the Anil and Bacanga river basins, with a volume of silt estimated at 8.5x106 m3, over the period from 1944 to 2011 (64 years, at a rate of 1.6 cm.yr-1. These processes are associated mainly with the construction of the Bacanga dam and land reclamation projects undertaken for the purpose of providing new areas for urban expansion. The evaluation of the results showed intense and advanced silting up of the São Luís tidal inlet, at rates proportionally greater than those of other estuaries, calling for corrective actions and the implementation of coastal management policies for this area.
Large-scale dissolved nutrient enrichment can cause a reduction in belowground biomass, increased water content of soils, and increased microbial decomposition, which has been linked with slumping of low marsh Spartina vegetation into creeks, and ultimately marsh loss. Our study ...
Suspended sediments from upstream tributaries as the source of downstream river sites
Haddadchi, Arman; Olley, Jon
2014-05-01
Understanding the efficiency with which sediment eroded from different sources is transported to the catchment outlet is a key knowledge gap that is critical to our ability to accurately target and prioritise management actions to reduce sediment delivery. Sediment fingerprinting has proven to be an efficient approach to determine the sources of sediment. This study examines the suspended sediment sources from Emu Creek catchment, south eastern Queensland, Australia. In addition to collect suspended sediments from different sites of the streams after the confluence of tributaries and outlet of the catchment, time integrated suspended samples from upper tributaries were used as the source of sediment, instead of using hillslope and channel bank samples. Totally, 35 time-integrated samplers were used to compute the contribution of suspended sediments from different upstream waterways to the downstream sediment sites. Three size fractions of materials including fine sand (63-210 μm), silt (10-63 μm) and fine silt and clay (<10 μm) were used to find the effect of particle size on the contribution of upper sediments as the sources of sediment after river confluences. And then samples were analysed by ICP-MS and -OES to find 41 sediment fingerprints. According to the results of Student's T-distribution mixing model, small creeks in the middle and lower part of the catchment were major source in different size fractions, especially in silt (10-63 μm) samples. Gowrie Creek as covers southern-upstream part of the catchment was a major contributor at the outlet of the catchment in finest size fraction (<10 μm) Large differences between the contributions of suspended sediments from upper tributaries in different size fractions necessitate the selection of appropriate size fraction on sediment tracing in the catchment and also major effect of particle size on the movement and deposition of sediments.
Owens, P. N.; Giles, T. R.; Blake, W. H.; Petticrew, E. L.; Bol, R.
2012-04-01
In August 2003 a severe wildfire burnt the majority of Fishtrap Creek, a 170 km2 watershed near the city of Kamloops in central British Columbia. The objective of this study was to determine the influence of the wildfire on the amount and composition of fine sediment delivery and transport in the system and to see if the wildfire altered the main sources of sediment. In addition, the findings are compared with that of a nearby watershed, Jamieson Creek, with similar characteristics that was unburnt. In both watersheds, suspended sediment concentrations and fluxes were determined using ISCO automatic water samplers. Changes in sediment sources were determined by collecting bulk sediment and source material samples, and by analysing these samples for a range of properties, including environmental radionuclides and C and N isotopes. Results suggest that following the wildfire there was no major response in fine sediment delivery and transport in Fishtrap Creek, when compared to Jamieson Creek, although there were noticeable differences in the composition of the fine sediment transported and stored in the channel bed. This muted response may be due to the fairly low rainfall amounts in the period immediately following the wildfire. Environmental fallout radionuclides (caesium-137 and unsupported lead-210) showed that there was limited increase (bank) sources of sediment. Recent changes in sediment fluxes and sediment sources relate more to bank erosion processes, probably due to loss of root strength and cohesion. The results suggest that in some situations wildfire may not produce the dramatic increases in hillslope erosion and sediment transport often documented in other watersheds. In Fishtrap Creek, channel bank erosion appears to be important in supplying fine material to the channel and this suggests that attention should be directed at managing the riparian zone in watersheds affected by wildfires.
DEFF Research Database (Denmark)
Turnewitsch, Robert; Falahat, Saeed; Stehlikova, Jirina
2014-01-01
finds evidence for another mechanism that is superimposed on, and counteracts, the focussing mechanism. This superimposed mechanism is related to higher-frequency (tidal, near-inertial) fluid dynamics. In particular, there is evidence for a strong and negative relation between the intensity...... but significant influence on particulate-matter dynamics and food supply in hadal trenches in particular, but possibly also in the deep seas in general. A mechanism for the influence of internal tides on sediment dynamics is proposed. (C) 2014 Elsevier Ltd. All rights reserved.......In addition to high hydrostatic pressure, scarcity of food is viewed as a factor that limits the abundance and activity of heterotrophic organisms at great ocean depths, including hadal trenches. Supply of nutritious food largely relies on the flux of organic-rich particulate matter from...
Wei, Xiaoyan; Kumar, Mohit; Schuttelaars, Henk M.
2018-02-01
To investigate the dominant sediment transport and trapping mechanisms, a semi-analytical three-dimensional model is developed resolving the dynamic effects of salt intrusion on sediment in well-mixed estuaries in morphodynamic equilibrium. As a study case, a schematized estuary with a converging width and a channel-shoal structure representative for the Delaware estuary is considered. When neglecting Coriolis effects, sediment downstream of the estuarine turbidity maximum (ETM) is imported into the estuary through the deeper channel and exported over the shoals. Within the ETM region, sediment is transported seaward through the deeper channel and transported landward over the shoals. The largest contribution to the cross-sectionally integrated seaward residual sediment transport is attributed to the advection of tidally averaged sediment concentrations by river-induced flow and tidal return flow. This contribution is mainly balanced by the residual landward sediment transport due to temporal correlations between the suspended sediment concentrations and velocities at the M2 tidal frequency. The M2 sediment concentration mainly results from spatial settling lag effects and asymmetric bed shear stresses due to interactions of M2 bottom velocities and the internally generated M4 tidal velocities, as well as the salinity-induced residual currents. Residual advection of tidally averaged sediment concentrations also plays an important role in the landward sediment transport. Including Coriolis effects hardly changes the cross-sectionally integrated sediment balance, but results in a landward (seaward) sediment transport on the right (left) side of the estuary looking seaward, consistent with observations from literature. The sediment transport/trapping mechanisms change significantly when varying the settling velocity and river discharge.
STUDY ON THE EFFECTS OF TIDE ON SEDIMENTATION IN ESTUARIES OF THE NIGER DELTA, NIGERIA
Directory of Open Access Journals (Sweden)
Charles Chizom Dike
2012-12-01
Full Text Available Niger Delta Estuary Nigeria is influenced by tidal currents due to its proximity to the Atlantic Ocean. Tides in the region are mostly semidiurnal, having two high and low water levels each day, with tidal prism ranging from 0.4 to 1.5m. The effects of tidal current reduces with distance inland and are strongest at the inlets with velocity varying from 2.0 to 5.0m/sec. The depth of the Estuary Rivers is controlled by the strength of the tidal currents; areas very close to ocean with stronger tidal effect are very deep; while shallow rivers predominates the hub of the estuary. Tidal current provides the steady supply of energy that moves sediments in and out of the estuaries from the seashore thus determing river bathymetric shapes through modification of existing morphology by eroding or depositing of sediments along the river course, while further sediment deposition is curtailed at the bottom as the estuary gets shallower due to the increasing stirring by waves. Despite all the sediment coming into the estuaries, many canals in the region have remained as open-water bodies, even after some thousand years. This suggests that, the interaction between the tide and the shape of the canal floor helps to regulate long-term sedimentation. However, the Dredged Canals in the Niger Delta estuaries have suffered high siltation rates because of excessive supply of sediments generated by storm/flood waters from upland and disposal of spoils from dredging activities into the water bodies, which causes some imbalance in the estuarine self-cleaning mechanism. Sediment loads entering the mangrove swamp environment are essentially polycentric; suspended fines enter the system both from the sea and the rivers. A mathematical model was formulated to predict and study the behavior of the sea bed levels, tidal heights and currents, in other to understand how they interact with each other. The model was calibrated using data obtained from local field observations
Hanes, Daniel M.; Barnard, Patrick L.; Dallas, Kate; Elias, Edwin; Erikson, Li H.; Eshleman, Jodi; Hansen, Jeff; Hsu, Tian Jian; Shi, Fengyan
2011-01-01
Recent research in the San Francisco, California, U.S.A., coastal region has identified the importance of the ebb tidal delta to coastal processes. A process-based numerical model is found to qualitatively reproduce the equilibrium size and shape of the delta. The ebb tidal delta itself has been contracting over the past century, and the numerical model is applied to investigate the sensitivity of the delta to changes in forcing conditions. The large ebb tidal delta has a strong influence upon regional coastal processes. The prominent bathymetry of the ebb tidal delta protects some of the coast from extreme storm waves, but the delta also focuses wave energy toward the central and southern portions of Ocean Beach. Wave focusing likely contributes to a chronic erosion problem at the southern end of Ocean Beach. The ebb tidal delta in combination with non-linear waves provides a potential cross-shore sediment transport pathway that probably supplies sediment to Ocean Beach.
Osburn, C. L.; Joshi, I.; Lebrasse, M. C.; Oviedo-Vargas, D.; Bianchi, T. S.; Bohnenstiehl, D. R.; D'Sa, E. J.; He, R.; Ko, D.; Arellano, A.; Ward, N. D.
2017-12-01
The contribution of blue carbon from tidal wetlands to the coastal ocean in the form of dissolved organic carbon (DOC) represents a terrestrial-aquatic linkage of increasing importance. DOC flux results will be presented from local (tidal creek) and regional (bays) scale studies in which various combinations of field observations, ocean-color satellite observations, and the outputs of high-resolution hydrodynamic models were used to estimate DOC export. The first project was located in Bald Head Creek, a tributary to the Cape Fear River estuary in eastern North Carolina (NC). DOC fluxes were computed using a bathymetric data collected via unmanned surface vehicle (USV) and a numerical hydrodynamic model (SCHISM) based on the relationships between colored dissolved organic matter (CDOM) absorption, DOC concentration, and salinity taken from field observations. Model predictions estimated an annual net export of DOC at 54 g C m-2 yr-1 from the tidal creek to the adjacent estuary. Carbon stable isotope (δ13C) values were used to estimate the contribution of wetland carbon to this export. In the second project, DOC fluxes from the Apalachicola Bay, FL, Barataria Bay, LA, were based on the development of algorithms between DOC and CDOM absorption derived from the VIIRS ocean color sensor. The Navy Coastal Ocean Model (NCOM) was used to compute salt flux estimates from each bay to the Louisiana-Texas shelf. The relationship between salinity and CDOM was used to estimate net annual DOC exports of 8.35 x 106 g C m-2 y-1 (Apalachicola Bay) and 7.14 x 106 g C m-2 yr-1 (Barataria Bay). These values approximate 13% and 9% of the annual loads of DOC from the Mississippi River to the Gulf of Mexico, respectively. CDOM and lignin were used in a mixing model to estimate wetland-derived DOC were 2% for Apalachicola Bay and 13% for Barataria Bay, the latter having one of the highest rates of relative sea level rise in North America. Results from our project demonstrated the utility
Results of the radiological survey at Two Mile Creek, Tonawanda, New York (TNY002)
International Nuclear Information System (INIS)
Murray, M.E.; Rodriguez, R.E.; Uziel, M.S.
1997-08-01
At the request of the US Department of Energy (DOE), a team from Oak Ridge National Laboratory conducted a radiological survey at Two Mile Creek, Tonawanda, New York. The survey was performed in November 1991 and May 1996. The purpose of the survey was to determine if radioactive materials from work performed under government contract at the Linde Air Products Division of Union Carbide Corporation, Tonawanda, New York, had been transported into the creek. The survey included a surface gamma scan in accessible areas near the creek and the collection of soil, sediment, and core samples for radionuclide analyses. Survey results indicate that no significant material originating at the Linde plant is presently in the creek. Three of the 1991 soil sample locations on the creek bank and one near the lake contained slightly elevated concentrations of 238 U with radionuclide distributions similar to that found in materials resulting from former processing activities at the Linde site
A watershed's response to logging and roads: South Fork of Caspar Creek, California, 1967-1976
Raymond M. Rice; Forest B. Tilley; Patricia A. Datzman
1979-01-01
The effect of logging and roadbuilding on erosion and sedimentation are analyzed by comparing the North Fork and South Fork of Caspar Creek, in northern California. Increased sediment production during the 4 years after road construction, was 326 cu yd/sq mi/yr—80 percent greater than that predicted by the predisturbance regression analysis. The average...
Energy Technology Data Exchange (ETDEWEB)
Barrett, Stephen B; Schlezinger, David, Ph.D; Cowles, Geoff, Ph.D; Hughes, Patricia; Samimy,; Roland, I; and Terray, E, Ph.D.
2012-12-29
potential for biofouling and foundation scouring. Woods Hole Oceanographic Institution, cooperating with SMAST, developed an oceanographic model to predict changes in sediment transport as a result of the proposed tidal energy project. Provincetown Center for Coastal Studies prepared background material on protected species - including whales, seals, and sea turtles - in the project area and implemented an initial tagging program to record location specific information on seals and sea turtles. HMMH communicated research plans and findings with local stakeholder groups, state and federal resource agency staff, and the ocean power industry. The information is being used to prepare environmental permit applications and obtain approvals for project construction.
International Nuclear Information System (INIS)
McKinnon, A. David; Trott, Lindsay A.; Brinkman, Richard; Duggan, Samantha; Castine, Sarah; O'Leary, Rebecca A.; Alongi, Daniel M.
2010-01-01
The fate of aquaculture wastes from a seacage farm within a pristine mangrove environment was studied. Seasonal and tidal differences were most important in determining water quality within receiving waters and obscured any nutrient enrichment effect by the farm. Farm wastes added significantly to the N budget status of the creek system, but overall water quality conformed to Queensland EPA Water Quality standards. Mangrove trees throughout the creek system contained 15 N signatures traceable to aquaculture feeds, but the footprint of the farm itself was best indicated by the ratio of Zn:Li in sediments. The creek became hypoxic ( -1 ) during wet season low tides. Consequently, we recommended monitoring of water-column oxygen concentrations to warn of hypoxic conditions threatening to fish health, as well as Zn:Li ratios in sediment accumulation zones to determine the area of influence of the farm.
The secret gardener: vegetation and the emergence of biogeomorphic patterns in tidal environments.
Da Lio, Cristina; D'Alpaos, Andrea; Marani, Marco
2013-01-01
The presence and continued existence of tidal morphologies, and in particular of salt marshes, is intimately connected with biological activity, especially with the presence of halophytic vegetation. Here, we review recent contributions to tidal biogeomorphology and identify the presence of multiple competing stable states arising from a two-way feedback between biomass productivity and topographic elevation. Hence, through the analysis of previous and new results on spatially extended biogeomorphological systems, we show that multiple stable states constitute a unifying framework explaining emerging patterns in tidal environments from the local to the system scale. Furthermore, in contrast with traditional views we propose that biota in tidal environments is not just passively adapting to morphological features prescribed by sediment transport, but rather it is 'The Secret Gardener', fundamentally constructing the tidal landscape. The proposed framework allows to identify the observable signature of the biogeomorphic feedbacks underlying tidal landscapes and to explore the response and resilience of tidal biogeomorphic patterns to variations in the forcings, such as the rate of relative sea-level rise.
Ockerman, Darwin J.
2008-01-01
The U.S. Geological Survey, in cooperation with the Texas State Soil and Water Conservation Board, Coastal Bend Bays and Estuaries Program, and Texas AgriLife Research and Extension Center at Corpus Christi, studied hydrologic conditions and quality of rainfall and storm runoff of two (primarily) agricultural areas (subwatersheds) of the Oso Creek watershed in Nueces County, Texas. One area, the upper West Oso Creek subwatershed, is 5,145 acres. The other area, a subwatershed drained by an unnamed Oso Creek tributary (hereinafter, Oso Creek tributary), is 5,287 acres. Rainfall and runoff (streamflow) were continuously monitored at the outlets of the two subwatersheds during October 2005-September 2007. Fourteen rainfall samples were collected and analyzed for nutrients and major inorganic ions. Nineteen composite runoff samples (10 West Oso Creek, nine Oso Creek tributary) were collected and analyzed for nutrients, major inorganic ions, and pesticides. Twenty-two discrete suspended-sediment samples (10 West Oso Creek, 12 Oso Creek tributary) and 13 bacteria samples (eight West Oso Creek, five Oso Creek tributary) were collected and analyzed. These data were used to estimate, for selected constituents, rainfall deposition to and runoff loads and yields from the study subwatersheds. Quantities of fertilizers and pesticides applied in the subwatersheds were compared with quantities of nutrients and pesticides in rainfall and runoff. For the study period, total rainfall was greater than average. Most of the runoff at both subwatershed outlet sites occurred in response to a few specific storm periods. The West Oso Creek subwatershed produced more runoff during the study period than the Oso Creek tributary subwatershed, 10.83 inches compared with 7.28 inches. Runoff response was quicker and peak flows were higher in the West Oso Creek subwatershed than in the Oso Creek tributary subwatershed. Total nitrogen runoff yield for the 2-year study period averaged 2.61 pounds
Linking human impacts within an estuary to ebb-tidal delta evolution
Dallas, Kate L.; Barnard, Patrick L.
2009-01-01
San Francisco Bay, California, USA is among the most anthropogenically altered estuaries in the entire United States, but the impact on sediment transport to the coastal ocean has not been quantified. Analysis of four historic bathymetric surveys has revealed large changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of the San Francisco Bay. From 1873 to 2005 the bar eroded an average of 80 cm, which equates to a total volume loss of 100 + 65 x 106 m3 of sediment. Comparison of the surveys indicates the entire ebb delta has contracted radially while its crest has moved landward an average of 1 km. Compilation of historic records reveals that 130 x 106 m3 of sediment has been permanently removed from the San Francisco Bay and adjacent coastal ocean. Constriction of the bar is hypothesized to be from a decrease in sediment supply from San Francisco Bay, a reduction in the tidal prism of the estuary, and/or a reduction in the input of hydraulic mining debris. Changes to the morphology of the San Francisco Bar have likely altered wave refraction and focusing patterns on adjacent beaches and may be a factor in persistent beach erosion occurring in the area.
Transport and deposition of asbestos-rich sediment in the Sumas River, Whatcom County, Washington
Curran, Christopher A.; Anderson, Scott W.; Barbash, Jack E.; Magirl, Christopher S.; Cox, Stephen E.; Norton, Katherine K.; Gendaszek, Andrew S.; Spanjer, Andrew R.; Foreman, James R.
2016-02-08
Heavy sediment loads in the Sumas River of Whatcom County, Washington, increase seasonal turbidity and cause locally acute sedimentation. Most sediment in the Sumas River is derived from a deep-seated landslide of serpentinite that is located on Sumas Mountain and drained by Swift Creek, a tributary to the Sumas River. This mafic sediment contains high amounts of naturally occurring asbestiform chrysotile. A known human-health hazard, asbestiform chrysotile comprises 0.25–37 percent, by mass, of the total suspended sediment sampled from the Sumas River as part of this study, which included part of water year 2011 and all of water years 2012 and 2013. The suspended-sediment load in the Sumas River at South Pass Road, 0.6 kilometers (km) downstream of the confluence with Swift Creek, was 22,000 tonnes (t) in water year 2012 and 49,000 t in water year 2013. The suspended‑sediment load at Telegraph Road, 18.8 km downstream of the Swift Creek confluence, was 22,000 t in water year 2012 and 27,000 t in water year 2013. Although hydrologic conditions during the study were wetter than normal overall, the 2-year flood peak was only modestly exceeded in water years 2011 and 2013; runoff‑driven geomorphic disturbance to the watershed, which might have involved mass wasting from the landslide, seemed unexceptional. In water year 2012, flood peaks were modest, and the annual streamflow was normal. The fact that suspended-sediment loads in water year 2012 were equivalent at sites 0.6 and 18.8 km downstream of the sediment source indicates that the conservation of suspended‑sediment load can occur under normal hydrologic conditions. The substantial decrease in suspended-sediment load in the downstream direction in water year 2013 was attributed to either sedimentation in the intervening river reach, transfer to bedload as an alternate mode of sediment transport, or both.The sediment in the Sumas River is distinct from sediment in most other river systems because of the
The Integration of Environmental Constraints into Tidal Array Optimisation
du Feu, Roan; de Trafford, Sebastian; Culley, Dave; Hill, Jon; Funke, Simon W.; Kramer, Stephan C.; Piggott, Matthew D.
2015-04-01
It has been estimated by The Carbon Trust that the marine renewable energy sector, of which tidal stream turbines are projected to play a large part, could produce 20% of the UK's present electricity requirements. This has lead to the important question of how this technology can be deployed in an economically and environmentally friendly manner. Work is currently under way to understand how the tidal turbines that constitute an array can be arranged to maximise the total power generated by that array. The work presented here continues this through the inclusion of environmental constraints. The benefits of the renewable energy sector to our environment at large are not in question. However, the question remains as to the effects this burgeoning sector will have on local environments, and how to mitigate these effects if they are detrimental. For example, the presence of tidal arrays can, through altering current velocity, drastically change the sediment transport into and out of an area along with re-suspending existing sediment. This can have the effects of scouring or submerging habitat, mobilising contaminants within the existing sediment, reducing food supply and altering the turbidity of the water. All of which greatly impact upon any fauna in the affected region. This work pays particular attention to the destruction of habitat of benthic fauna, as this is quantifiable as a direct result of change in the current speed; a primary factor in determining sediment accumulation on the sea floor. OpenTidalFarm is an open source tool that maximises the power generated by an array through repositioning the turbines within it. It currently uses a 2D shallow water model with turbines represented as bump functions of increased friction. The functional of interest, power extracted by the array, is evaluated from the flow field which is calculated at each iteration using a finite element method. A gradient-based local optimisation is then used through solving the
McCarthy, K.; Affinito, R. A.; Pizzuto, J. E.; Stotts, S.; Henry, T.; Krauthauser, M.; O'Neal, M. A.
2017-12-01
Quantifying contemporary sediment budgets is essential for restoration and ecosystem management of mid-Atlantic watersheds, but relevant processes and controls are poorly understood. In the 153 km2 White Clay Creek watershed in southeastern Pennsylvania, longitudinal profiles reflect migration of knickpoints though bedrock over Quaternary timescales. In bank exposures along stream valleys, saprolite, bedrock, and matrix-supported cobbly and bouldery diamicton (likely colluvial) commonly underlie finer-grained clay, silt, sand, and gravel deposits of valley floor depositional environments. Overbank sedimentation rates were quantified by measuring the thickness of sediment deposited over the roots of floodplain trees. The sampled trees range in age from 25-270 years with median sediment accumulation rates of approximately 2 mm/yr (range 0-10 mm/yr). Rates of bank retreat (measured from historical aerial imagery or root-exposure dendrochronology) vary from 6-36 cm/yr, with median rates of 10 cm/yr. While bank erosion rates are subject to a variety of controls, including channel curvature, the density of riparian trees, and freeze-thaw processes, the strongest influence appears to be the grain size and thickness of bouldery diamicton exposed along the toes of retreating banks. Cobbles and boulders supplied by eroding diamicton also mantle the bed of the channel, such that 33- 80% of the bed material remains immobile at bankfull stage. A conceptual model of fluvial processes and sediment budgets for these channels must account for the watershed's history of changing climate, tectonics, and land use, requiring mapping of bedrock, colluvium, former mill dam sediments, and other non-alluvial deposits and controls. Efforts to apply hydraulic geometry principles (requiring a precise adjustment to contemporary hydraulic and sediment regime) or to treat these channels as traditional "threshold" rivers are unlikely to be successful.
Buck Creek River Flow Analysis
Dhanapala, Yasas; George, Elizabeth; Ritter, John
2009-04-01
Buck Creek flowing through Springfield Ohio has a number of low-head dams currently in place that cause safety issues and sometimes make it impossible for recreational boaters to pass through. The safety issues include the back eddies created by the dams that are known as drowning machines and the hydraulic jumps. In this study we are modeling the flow of Buck Creek using topographical and flow data provided by the Geology Department of Wittenberg University. The flow is analyzed using Hydraulic Engineering Center - River Analysis System software (HEC-RAS). As the first step a model of the river near Snyder Park has been created with the current structure in place for validation purposes. Afterwards the low-head dam is replaced with four drop structures with V-notch overflow gates. The river bed is altered to reflect plunge pools after each drop structure. This analysis will provide insight to how the flow is going to behave after the changes are made. In addition a sediment transport analysis is also being conducted to provide information about the stability of these structures.
Leclere, S.; Sklar, L. S.; Genetti, J. R.
2014-12-01
The size distribution of sediments produced on hillslopes and supplied to channels depends on the geomorphic processes that weather, detach and transport rock fragments down slopes. Little in the way of theory or data is available to predict patterns in hillslope size distributions at the catchment scale from topographic and geologic maps. Here we use aerial imagery and a variety of remote sensing techniques to map and categorize geomorphic landscape units (GLUs) by inferred sediment production process regime, across the steep mountain catchment of Inyo Creek, eastern Sierra Nevada, California. We also use field measurements of particle size and local geomorphic attributes to test and refine GLU determinations. Across the 2 km of relief in this catchment, landcover varies from bare bedrock cliffs at higher elevations to vegetated, regolith-covered convex slopes at lower elevations. Hillslope gradient could provide a simple index of sediment production process, from rock spallation and landsliding at highest slopes, to tree-throw and other disturbance-driven soil production processes at lowest slopes. However, many other attributes are needed for a more robust predictive model, including elevation, curvature, aspect, drainage area, and color. We combine tools from ArcGIS, ERDAS Imagine and Envi with groundtruthing field work to find an optimal combination of attributes for defining sediment production GLUs. Key challenges include distinguishing: weathered from freshly eroded bedrock, boulders from intact bedrock, and landslide deposits from talus slopes. We take advantage of emerging technologies that provide new ways of conducting fieldwork and comparing field data to mapping solutions. In particular, cellphone GPS is approaching the accuracy of dedicated GPS systems and the ability to geo-reference photos simplifies field notes and increases accuracy of later map creation. However, the predictive power of the GLU mapping approach is limited by inherent uncertainty
Timoney, Kevin; Lee, Peter
2016-04-01
Deltas form where riverborne sediment accumulates at the interface of river mouths and their receiving water bodies. Their areal extent is determined by the net effect of processes that increase their extent, such as sediment accumulation, and processes that decrease their extent, such as erosion and subsidence. Through sequential mapping and construction of river discharge and sediment histories, this study examined changes in the subaerial extents of the Cree Creek and Athabasca River Deltas (both on the Athabasca River system) and the Birch River Delta in northern Canada over the period 1950-2014. The purpose of the study was to determine how, when, and why the deltas changed in areal extent. Temporal growth patterns were similar across the Athabasca and Birch River systems indicative of a climatic signal. Little or no areal growth occurred from 1950 to 1968; moderate growth occurred between 1968 and the early to mid-1980s; and rapid growth occurred between 1992 and 2012. Factors that affected delta progradation included dredging, sediment supply, isostatic drowning, delta front bathymetry, sediment capture efficiency, and storms. In relation to sediment delivered, areal growth rates were lowest in the Athabasca Delta, intermediate in the Birch Delta, and highest in the Cree Creek Delta. Annual sediment delivery is increasing in the Cree Creek Delta; there were no significant trends in annual sediment delivery in the Birch and Athabasca Deltas. There was a lag of up to several years between sediment delivery events and progradation. Periods of delta progradation were associated with low water levels of the receiving basins. Predicted climate-change driven declines in river discharge and lake levels may accelerate delta progradation in the region. In the changing ecosystems of northeastern Alberta, inadequate monitoring of vegetation, landforms, and sediment regimes hampers the elucidation of the nature, rate, and causality of ecosystem changes.
Research on Local Scour at Bridge Pier under Tidal Action
Directory of Open Access Journals (Sweden)
Wang Jianping
2015-01-01
Full Text Available Through the local scour test at bridge pier under tidal action in a long time series, this paper observes the growing trend of the deepest point of local scour at bridge pier under tidal conditions with different characteristic parameters, analyzes the impact of repeat sediment erosion and deposition in the scouring pit caused by reversing current on the development process of the scouring pit, and clarifies the relation between the tide and local scouring depth at bridge pier under steady flow conditions, so as to provide a scientific basis for bridge design and safe operation of estuary and harbor areas.
Digital Repository Service at National Institute of Oceanography (India)
Fernandes, L.L.; Kessarkar, P.M.; Parthiban, G.; Rao, V.P.
The role of diagenetic processes in influencing the behaviour of metals (Fe, Mn, Cu, Ni, Zn), rare earth elements (REEs) and environmental magnetic parameters in two sediment cores from a polluted creek environment (the Thane Creek, Mumbai...
Erosion and Sedimentation from the Bagley Fire, Eastern Klamath Mountains, Northern CA
De La Fuente, J. A.; Bachmann, S.; Mai, C.; Mikulovsky, R.; Mondry, Z. J.; Rust, B.; Young, D.
2014-12-01
The Bagley Fire burned about 19,000 hectares on the Shasta-Trinity National Forest in the late summer of 2012, with soil burn severities of 11% high, 19% moderate and 48% low. Two strong storms in November and December followed the fire. The first storm had a recurrence interval of about 2 years, and generated runoff with a return interval of 10-25 years, causing many road stream crossing failures in parts of the fire. The second storm had a recurrence interval of 25-50 years, and initiated more severe erosion throughout the fire area. Erosional processes were dominated by sheet, rill and gully erosion, and landslides were uncommon. A model predicted high potential for debris flows, but few were documented, and though most stream channels exhibited fresh scour and deposition, residual deposits lacked boulder levees or other evidence of debris flow. Rather, deposits were stratified and friable, suggesting a sediment laden flood flow rather than debris flow origin. The resulting sediment was rich in gravel and finer particles, and poor in larger rock. Soil loss was estimated at 0.5-5.6 cm on most hillslopes. A high resolution DEM (LiDAR) was used to measure gullies, small landslides, and stream scour, and also to estimate sedimentation in Squaw Creek, and Shasta Lake. A soil erosion model was used to estimate surface erosion. Total erosion in the Squaw Creek watershed was estimated at 2.24 million metric tons, which equates to 260 metric tons/hectare. Of this, about 0.89 million metric tons were delivered to the stream system (103 metric tons/hectare). Nearly half of this sediment, 0.41 million metric tons, was temporarily stored in the Squaw Creek channel, and around 0.33 million metric tons of fine sediment were carried into Shasta Lake. Squaw Creek also delivered about 0.17 million metric tons of sand, gravel and cobbles to the lake. This estimate is very tenuous, and was made by measuring the volume of a delta in Shasta Lake from a tributary to Squaw Creek and
Directory of Open Access Journals (Sweden)
Philip A. Gillibrand
2016-10-01
Full Text Available We apply a three-dimensional hydrodynamic model to consider the potential effects of energy extraction by an array of tidal turbines on the ambient near-bed velocity field and local bed shear stress in a coastal channel with strong tidal currents. Local bed shear stress plays a key role in local sediment dynamics. The model solves the Reynold-averaged Navier-Stokes (RANS equations on an unstructured mesh using mixed finite element and finite volume techniques. Tidal turbines are represented through an additional form drag in the momentum balance equation, with the thrust imparted and power generated by the turbines being velocity dependent with appropriate cut-in and cut-out velocities. Arrays of 1, 4 and 57 tidal turbines, each of 1.5 MW capacity, were simulated. Effects due to a single turbine and an array of four turbines were negligible. The main effect of the array of 57 turbines was to cause a shift in position of the jet through the tidal channel, as the flow was diverted around the tidal array. The net effect of this shift was to increase near-bed velocities and bed shear stress along the northern perimeter of the array by up to 0.8 m·s−1 and 5 Pa respectively. Within the array and directly downstream, near-bed velocities and bed shear stress were reduced by similar amounts. Changes of this magnitude have the potential to modify the known sand and shell banks in the region. Continued monitoring of the sediment distributions in the region will provide a valuable dataset on the impacts of tidal energy extraction on local sediment dynamics. Finally, the mean power generated per turbine is shown to decrease as the turbine array increased in size.
International Nuclear Information System (INIS)
Abdul Kadir Ishak
2006-01-01
Field studies to determine the hydrodynamics and fine-sediment transport were carried out at the Kapar coastal region, on the west coast of the Malaysian Peninsula. Several observation stations were established to measure near-bed tidal currents, suspended sediment concentration (SSC), water temperature, salinity and tidal elevation. It was found that resuspension (erosion) and deposition of fine sediment occurred during every tidal cycle, with greater transport occurred during the ebb than the flood. This become the major source of fine sediment that contribute to the siltation problem in this region. The high resuspension and entrainment of sediment into the flow column was due to a high near-bed current velocity which was at its peak at 1.3 m/s (during spring tides) and easily-eroded fine particles recently settled during previous tidal cycles. Significant erosion (and deposition) took place during the spring tides but little erosion was observed during the neap. The secondary source of fine sediment is from Sungai Kelang transported to the area by ebb currents in particular during spring tides. The measurement data also showed that the current flows around an industrial construction, the Kapar power station, had been modified and greatly reduced, which had resulted in a significant siltation problem in this region. This study contributes to a better understanding of the influence of hydrodynamics on the physical processes relating to the resuspension, transport and deposition of the fine-sediment in this region. (Author)
Schenk, E.R.; Hupp, C.R.
2009-01-01
Many rivers and streams of the Mid-Atlantic Region, United States (U.S.) have been altered by postcolonial floodplain sedimentation (legacy sediment) associated with numerous milldams. Little Conestoga Creek, Pennsylvania, a tributary to the Susquehanna River and the Chesapeake Bay, is one of these streams. Floodplain sedimentation rates, bank erosion rates, and channel morphology were measured annually during 2004-2007 at five sites along a 28-km length of Little Conestoga Creek with nine colonial era milldams (one dam was still in place in 2007). This study was part of a larger cooperative effort to quantify floodplain sedimentation, bank erosion, and channel morphology in a high sediment yielding region of the Chesapeake Bay watershed. Data from the five sites were used to estimate the annual volume and mass of sediment stored on the floodplain and eroded from the banks for 14 segments along the 28-km length of creek. A bank and floodplain reach based sediment budget (sediment budget) was constructed for the 28 km by summing the net volume of sediment deposited and eroded from each segment. Mean floodplain sedimentation rates for Little Conestoga Creek were variable, with erosion at one upstream site (-5 mm/year) to deposition at the other four sites (highest = 11 mm/year) despite over a meter of floodplain aggradation from postcolonial sedimentation. Mean bank erosion rates range between 29 and 163 mm/year among the five sites. Bank height increased 1 m for every 10.6 m of channel width, from upstream to downstream (R2 = 0.79, p channel and the floodplain. Floodplain sedimentation and bank erosion rates also appear to be affected by the proximity of the segments to one existing milldam, which promotes deposition upstream and scouring downstream. The floodplain and bank along the 28-km reach produced a net mean sediment loss of 5,634 Mg/year for 2004-2007, indicating that bank erosion was exceeding floodplain sedimentation. In particular, the three segments
Controls on sediment cover in bedrock-alluvial channels of the Henry Mountains, Utah
Hodge, R. A.; Yager, E.; Johnson, J. P.; Tranmer, A.
2017-12-01
The location and extent of sediment cover in bedrock-alluvial channels influences sediment transport rates, channel incision and instream ecology. However, factors affecting sediment cover and how it responds to changes in relative sediment supply have rarely been quantitatively evaluated in field settings. Using field surveys and SFM analysis of channel reach topography, we quantified sediment cover and channel properties including slope, width, grain size distributions, and bedrock and alluvial roughness in North Wash and Chelada Creek in the Henry Mountains, Utah. Along reaches where upstream sediment supply does not appear to be restricted, we find that the fraction of local bedrock exposure increases as a function of local relative transport capacity . In a downstream section of Chelada Creek, decadal-scale sediment supply has been restricted by an upstream culvert that has caused a backwater effect and corresponding upstream deposition. In this section, alluvial cover is uncorrelated with local stream power. To test the impact of relative sediment supply on sediment cover, a 1D sediment transport model was used to predict the equilibrium sediment cover in Chelada Creek under varying flow and sediment supply conditions. Sediment transport in each model section was predicted using the partial cover model of Johnson (2015), which accounts for differences in bedrock and alluvial roughness on critical shear stress and flow resistance. Model runs in which sediment supply was approximately equal to mean transport capacity produced a pattern of sediment cover which best matched the field observations upstream of the culvert. However, runs where sediment supply was under-capacity produced the pattern most similar to field observations downstream of the culvert, consistent with our field-based interpretations. Model results were insensitive to initial sediment cover, and equilibrium was relatively quickly reached, suggesting that the channel is responsive to changes in
International Nuclear Information System (INIS)
Ewers, G.R.; Ferguson, J.; Needham, R.S.; Donnelly, T.H.
1984-01-01
The Pine Creek Geosyncline comprises about 14 km of chronostratigraphic mainly pelitic and psammitic Early Proterozoic sediments with interlayered tuff units, resting on granitic late Archaean complexes exposed as small domes. Sedimentation took place in one basin, and most stratigraphic units are represented throughout the basin. The sediments were regionally deformed and metamorphosed at 1800 Ma. Tightly folded greenschist facies strata in the centre grade into isoclinally deformed amphibolite facies metamorphics in the west and northeast, granulites are present in the extreme northeast. Pre and post-orogenic continental tholeiites, and post-orogenic granite diapirs intrude the Early Proterozoic metasediments, and the granites are surrounded by hornfels zones up to 10 km wide in the greenschist facies terrane. Cover rocks of Carpentarian (Middle Proterozoic) and younger ages rest on all these rocks unconformably and conceal the original basin margins. The uranium deposits post-date the approx. 1800 Ma regional metamorphic event; isotopic dating of uraninite and galena in the ore bodies indicates ages of mineralisation at approx. 1600 Ma, approx. 900 Ma and approx. 500 Ma. The ore bodies are stratabound, located within breccia zones, are of a shallow depth, and occur immediately below the Early/Middle Proterozoic unconformity
Schenk, E.R.; Hupp, C.R.
2009-01-01
Many rivers and streams of the Mid-Atlantic Region, United States (U.S.) have been altered by postcolonial floodplain sedimentation (legacy sediment) associated with numerous milldams. Little Conestoga Creek, Pennsylvania, a tributary to the Susquehanna River and the Chesapeake Bay, is one of these streams. Floodplain sedimentation rates, bank erosion rates, and channel morphology were measured annually during 2004-2007 at five sites along a 28-km length of Little Conestoga Creek with nine colonial era milldams (one dam was still in place in 2007). This study was part of a larger cooperative effort to quantify floodplain sedimentation, bank erosion, and channel morphology in a high sediment yielding region of the Chesapeake Bay watershed. Data from the five sites were used to estimate the annual volume and mass of sediment stored on the floodplain and eroded from the banks for 14 segments along the 28-km length of creek. A bank and floodplain reach based sediment budget (sediment budget) was constructed for the 28 km by summing the net volume of sediment deposited and eroded from each segment. Mean floodplain sedimentation rates for Little Conestoga Creek were variable, with erosion at one upstream site (-5 mm/year) to deposition at the other four sites (highest = 11 mm/year) despite over a meter of floodplain aggradation from postcolonial sedimentation. Mean bank erosion rates range between 29 and 163 mm/year among the five sites. Bank height increased 1 m for every 10.6 m of channel width, from upstream to downstream (R2 = 0.79, p scouring downstream. The floodplain and bank along the 28-km reach produced a net mean sediment loss of 5,634 Mg/year for 2004-2007, indicating that bank erosion was exceeding floodplain sedimentation. In particular, the three segments between the existing dam and the confluence with the Conestoga River (32% of the studied reach) account for 97% of the measured net sediment budget. Future research directed at understanding channel
International Nuclear Information System (INIS)
Praveena, S.M.; Ahmed, A.; Radojevic, M.; Mohd Harun Abdullah; Aris, A.Z.
2007-01-01
This paper examines the tidal effects in the sediment of Mengkabong mangrove forest, Sabah. Generally, all the studied parameters showed high value at high tide compared to low tide. Factor-cluster analyses were adopted to allow the identification of controlling factors at high and low tides. Factor analysis extracted six controlling factors at high tide and seven controlling factors at low tide. Cluster analysis extracted two district clusters at high and low tides. The study showed that factor-cluster analysis application is a useful tool to single out the controlling factors at high and low tides. this will provide a basis for describing the tidal effects in the mangrove sediment. The salinity and electrical conductivity clusters as well as component loadings at high and low tide explained the tidal process where there is high contribution of seawater to mangrove sediments that controls the sediment chemistry. The geo accumulation index (T geo ) values suggest the mangrove sediments are having background concentrations for Al, Cu, Fe and Zn and unpolluted for Pb. (author)
A water-quality study of the tidal Potomac River and Estuary: An overview
Callendar, Edward; Carter, Virginia; Hahl, D.C.; Hitt, Kerie; Schultz, Barbara I.
1984-01-01
The U.S. Geological Survey began a 5-year interdisciplinary study of the tidal Potomac River and Estuary in October of 1977. The objectives of the study are: (1) to provide a basic understanding of physical, chemical, and biological processes; (2) to develop flow and transport models to predict the movement and fate of nutrients and algaes and (3) to develop efficient techniques for the study of tidal rivers and estuaries. The ultimate goal is to aid water-quality decision-making for the tidal Potomac River and Estuary. The study is being conducted by scientists from many disciplines involved in 14 interrelated studies. These scientists are addressing five major problem areas: nutrient enrichment, algal blooms, dissolved oxygen, sedimentation, and effects of water quality on living resources. Preliminary results show that treatment of sewage has reduced the concentration load of organic carbon and phosphorus below that of the 1960's and 1970's, and changed the form of dissolved nitrogen in the tidal river. Concentrations of chlorophyll a during the study period were lower than those experienced during the massive algal blooms of the 1960's. Dissolved oxygen concentrations fluctuate in response to changes in algal populations, but remain above the Environmental Protection Agency limits during the summer low-flow period. Sedimentation rates have accelerated during the past 50-70 years due to urbanization and farming. Asian clams have recently invaded the tidal river; submersed aquatic vegetation has declined since the early 1900's, but conditions may now favor its return.
Kleinhans, Maarten G.; van der Vegt, Maarten; Leuven, Jasper; Braat, Lisanne; Markies, Henk; Simmelink, Arjan; Roosendaal, Chris; van Eijk, Arjan; Vrijbergen, Paul; van Maarseveen, Marcel
2017-11-01
Analogue models or scale experiments of estuaries and short tidal basins are notoriously difficult to create in the laboratory because of the difficulty to obtain currents strong enough to transport sand. Our recently discovered method to drive tidal currents by periodically tilting the entire flume leads to intense sediment transport in both the ebb and flood phase, causing dynamic channel and shoal patterns. However, it remains unclear whether tilting produces periodic flows with characteristic tidal properties that are sufficiently similar to those in nature for the purpose of landscape experiments. Moreover, it is not well understood why the flows driven by periodic sea level fluctuation, as in nature, are not sufficient for morphodynamic experiments. Here we compare for the first time the tidal currents driven by sea level fluctuations and by tilting. Experiments were run in a 20 × 3 m straight flume, the Metronome, for a range of tilting periods and with one or two boundaries open at constant head with free inflow and outflow. Also, experiments were run with flow driven by periodic sea level fluctuations. We recorded surface flow velocity along the flume with particle imaging velocimetry and measured water levels along the flume. We compared the results to a one-dimensional model with shallow flow equations for a rough bed, which was tested on the experiments and applied to a range of length scales bridging small experiments and large estuaries. We found that the Reynolds method results in negligible flows along the flume except for the first few metres, whereas flume tilting results in nearly uniform reversing flow velocities along the entire flume that are strong enough to move sand. Furthermore, tidal excursion length relative to basin length and the dominance of friction over inertia is similar in tidal experiments and reality. The sediment mobility converges between the Reynolds method and tilting for flumes hundreds of metres long, which is impractical
Directory of Open Access Journals (Sweden)
M. G. Kleinhans
2017-11-01
Full Text Available Analogue models or scale experiments of estuaries and short tidal basins are notoriously difficult to create in the laboratory because of the difficulty to obtain currents strong enough to transport sand. Our recently discovered method to drive tidal currents by periodically tilting the entire flume leads to intense sediment transport in both the ebb and flood phase, causing dynamic channel and shoal patterns. However, it remains unclear whether tilting produces periodic flows with characteristic tidal properties that are sufficiently similar to those in nature for the purpose of landscape experiments. Moreover, it is not well understood why the flows driven by periodic sea level fluctuation, as in nature, are not sufficient for morphodynamic experiments. Here we compare for the first time the tidal currents driven by sea level fluctuations and by tilting. Experiments were run in a 20 × 3 m straight flume, the Metronome, for a range of tilting periods and with one or two boundaries open at constant head with free inflow and outflow. Also, experiments were run with flow driven by periodic sea level fluctuations. We recorded surface flow velocity along the flume with particle imaging velocimetry and measured water levels along the flume. We compared the results to a one-dimensional model with shallow flow equations for a rough bed, which was tested on the experiments and applied to a range of length scales bridging small experiments and large estuaries. We found that the Reynolds method results in negligible flows along the flume except for the first few metres, whereas flume tilting results in nearly uniform reversing flow velocities along the entire flume that are strong enough to move sand. Furthermore, tidal excursion length relative to basin length and the dominance of friction over inertia is similar in tidal experiments and reality. The sediment mobility converges between the Reynolds method and tilting for flumes hundreds of
Modelling of sediment transport at Muria peninsula coastal, Jepara
International Nuclear Information System (INIS)
Heni Susiati; Yarianto SBS; Wahyu Pandoe; Eko Kusratmoko; Aris Poniman
2010-01-01
Modelling of transport sediment modelling at Muria Peninsula have been done. In this study we had been used mathematical model that consist of hydrodynamics and sediment transport . Data input for modelling has been used tidal, monsoon wind, and river debit. Simulation result of sediment transport modelling showed that tides pattern and seasonal variations are the main causes of variations in the suspended sediment distribution in Muria Peninsula. (author)
Frenzel, Steven A.
2000-01-01
Organochlorines, semivolatile organic compounds (SVOCs), and trace elements were investigated in streambed sediments and fish tissues at selected sites in the Cook Inlet Basin, Alaska, during 1998. At most sites, SVOCs and organochlorine compounds were either not detected or detected at very low concentrations. Chester Creek at Arctic Boulevard at Anchorage, which was the only site sampled with a significant degree of development in the watershed, had elevated levels of many SVOCs in streambed sediment. Coring of sediments from two ponds on Chester Creek confirmed the presence of elevated concentrations of a variety of organic compounds. Moose Creek, a stream with extensive coal deposits in its watershed, had low concentrations of numerous SVOCs in streambed sediment. Three sites located in national parks or in a national wildlife refuge had no detectable concentrations of SVOCs. Trace elements were analyzed in both streambed sediments and tissues of slimy sculpin. The two media provided similar evidence for elevated concentrations of cadmium, lead, and zinc at Chester Creek. In this study, 'probable effect levels '(PELs) were determined from sediments finer than 0.063 millimeters, where concentrations tend to be greatest. Arsenic and chromium concentrations exceeded the PEL at eight and six sites respectively. Zinc exceeded the PEL at one site. Cadmium and copper concentrations were smaller than the PEL at all sites. Mercury concentrations in streambed sediments from the Deshka River were near the PEL, and selenium concentrations at that site also appear to be elevated above background levels. At half the sites where slimy sculpin were sampled, selenium concentrations were at levels that may cause adverse effects in some species.
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-03-01
This Sampling and Analysis Plan (SAP) for the Bear Creek Valley (BCV) Floodplain presents the approach and rationale for characterizing potentially contaminated soils and sediments of the Bear Creek floodplain and the impact of any contaminants on the floodplain ecosystem. In addition to this SAP, the Remedial Investigation Work Plan for Bear Creek (Y02-S600) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee (ES/ER-19&D2) presents background information pertaining to this floodplain investigation.
International Nuclear Information System (INIS)
1995-03-01
This Sampling and Analysis Plan (SAP) for the Bear Creek Valley (BCV) Floodplain presents the approach and rationale for characterizing potentially contaminated soils and sediments of the Bear Creek floodplain and the impact of any contaminants on the floodplain ecosystem. In addition to this SAP, the Remedial Investigation Work Plan for Bear Creek (Y02-S600) at the Oak Ridge Y-12 Plant, Oak Ridge, Tennessee (ES/ER-19 ampersand D2) presents background information pertaining to this floodplain investigation
Asymmetric fluxes of water and sediments in a mesotidal mudflat channel
Mariotti, G.; Fagherazzi, S.
2011-01-01
The hydrodynamics of a small tributary channel and its adjacent mudflat is studied in Willapa Bay, Washington State, USA. Velocity profiles and water levels are simultaneously measured at different locations in the channel and on the mudflat for two weeks. The above tidal flat and channel hydrodynamics differ remarkably during the tidal cycle. When the water surface level is above the tidal flat elevation, the channel is inactive. At this stage, the above tidal flat flow is predominantly aligned along the Bay axis, oscillating with the tide as a standing wave with peak velocities up to 0.3 m/s. When the mudflat becomes emergent, the flow concentrates in the channel. During this stage, current velocities up to 1 m/s are measured during ebb; and up to 0.6 m/s during flood. Standard equations for open-channel flow are utilized to study the channel hydrodynamics. From the continuity equation, a lateral inflow is predicted during ebb, which likely originates from the drainage of the mudflat through the lateral runnels. Both advective acceleration and lateral discharge terms, estimated directly from the velocity profiles, play a significant role in the momentum equation. The computed drag coefficient for bottom friction is small, due to an absence of vegetation and bottom bedforms in the channel. Sediment fluxes are calculated by combining flow and suspended sediment concentration estimated using the acoustic backscatter signal of the instruments. A net export of the sediment from the channel is found during ebb, which is not balanced by the sediment import during flood. When the mudflat is submerged, ebb-flood asymmetries in suspended sediment concentration are present, leading to a net sediment flux toward the inner part of the Willapa Bay. Finally, a residual flow is detected inside the channel at high slack water, probably associated with the thermohaline circulation.
Salt Marsh Ecosystem Responses to Restored Tidal Connectivity across a 14y Chronosequence
Capooci, M.; Spivak, A. C.; Gosselin, K.
2016-02-01
Salt marshes support valuable ecosystem services. Yet, human activities negatively impact salt marsh function and contribute to their loss at a global scale. On Cape Cod, MA, culverts and impoundments under roads and railways restricted tidal exchange and resulted in salt marsh conversion to freshwater wetlands. Over the past 14 y, these structures have been removed or replaced, restoring tidal connectivity between marshes and a saltwater bay. We evaluated differences in plant community composition, sediment properties, and pore water chemistry in marshes where tidal connectivity was restored using a space-for-time, or chronosequence approach. Each restored marsh was paired with a nearby, natural salt marsh to control for variability between marshes. In each restored and natural salt marsh we evaluated the plant community by measuring species-specific percent cover and biomass and collected sediment cores for bulk density and pore water analyses. Plant communities responded rapidly: salt-tolerant species, such as Spartina alterniflora, became established while freshwater species, including Phragmites australis, were less abundant within 3 y of restoration. The number of plant species was generally greater in marshes restored within 10 y, compared to older and natural marshes. Sediment bulk density varied with depth and across sites. This likely reflects differences in site history and local conditions. Deeper horizons (24-30cm) generally had higher values in restored sites while surface values (0-3cm) were similar in restored and natural marshes. Porewater pH and sulfide were similar in restored and natural marshes, suggesting rapid microbial responses to seawater reintroduction. Overall, marsh properties and processes reflecting biological communities responded rapidly to tidal restoration. However, variability between study locations underscores the potential importance of site history, local hydrology, and geomorphology in shaping marsh biogeochemistry.
Sediment-driven mercury transport in post-fire storm runoff
Burke, M. P.; Ferreira, M.; Hogue, T. S.; Jay, J.; Rademacher, L. K.
2009-12-01
Wildfire alters terrestrial stores of mercury (Hg) within a watershed, releasing Hg to the atmosphere and creating conditions that can be conducive to Hg export in streamwater. Hg transport to terrestrial waters is often associated with suspended sediments and organic matter, and particulate-bound Hg delivery to downstream water bodies may be enhanced following wildfire. Burned watersheds experience increased overland flow, soil erosion, sediment transport, and, consequently, transport of sediment bound contaminants during early post-fire storm events. Southern California’s September 2006 Day Fire consumed 660km2 and almost 50% of the 512km2 Piru Creek watershed. Piru Creek drains into Pyramid Lake, a storage reservoir for the California State Water Project, which provides drinking water for Los Angeles. Streamwater was collected from Piru Creek watershed over a 1.5 year period following the Day Fire, on a monthly basis during low flow periods, and every two hours during storm events using an automated sampler. Samples were analyzed for both dissolved and total Hg, total suspended solids, and basic anions and cations. Low Hg concentrations (> 1ng Hg/ L dissolved and > 5ng Hg/L total) were measured in inter-storm samples. The first winter (2006-07) following the Day Fire was one of the driest on record, with precipitation totals (130mm) less than one third of normal. The only significant storm measured total Hg concentrations just slightly higher than the inter-storm samples, while no change was observed in the dissolved Hg concentrations. However, these total Hg concentrations were well correlated to TSS measurements (r2 = 0.91) and followed the storm hydrograph. The following winter (2007-08) brought higher precipitation totals (370mm) and more intense storms. Elevated, turbid stream flow was observed in Piru Creek during many of the 2007-08 storms. Little change was observed in the dissolved Hg concentrations of the storm samples; however, a two-order magnitude
Habitat Projects Completed within the Asotin Creek Watershed, 1999 Completion Report.
Energy Technology Data Exchange (ETDEWEB)
Johnson, Bradley J.
2000-01-01
The Asotin Creek Model Watershed Program (ACMWP) is the primary entity coordinating habitat projects on both private and public lands within the Asotin Creek watershed. The Asotin Creek watershed covers approximately 325 square miles in the Blue Mountains of southeastern Washington in WRIA 35. According to WDFW's Priority WRIA's by At-Risk Stock Significance Map, it is the highest priority in southeastern WA. Snake River spring chinook salmon, summer steelhead and bull trout, which are listed under the Endangered Species Act (ESA), are present in the watershed. The ACMWP began coordinating habitat projects in 1995. Approximately two hundred seventy-six projects have been implemented through the ACMWP as of 1999. Twenty of these projects were funded in part through Bonneville Power Administration's 1999 Columbia Basin Fish and Wildlife Program. These projects used a variety of methods to enhance and protect watershed conditions. In-stream work for fish habitat included construction of hard structures (e.g. vortex rock weirs), meander reconstruction, placement of large woody debris (LWD) and whole trees and improvements to off-channel rearing habitat; thirty-eight were created with these structures. Three miles of stream benefited from riparian improvements such as vegetative plantings (17,000 trees and shrubs) and noxious weed control. Two sediment basin constructions, 67 acres of grass seeding, and seven hundred forty-five acres of minimum till were implemented to reduce sediment production and delivery to streams in the watershed.
Sediment Trapping in Estuaries
Burchard, Hans; Schuttelaars, Henk M.; Ralston, David K.
2018-01-01
Estuarine turbidity maxima (ETMs) are generated by a large suite of hydrodynamic and sediment dynamic processes, leading to longitudinal convergence of cross-sectionally integrated and tidally averaged transport of cohesive and noncohesive suspended particulate matter (SPM). The relative importance of these processes for SPM trapping varies substantially among estuaries depending on topography, fluvial and tidal forcing, and SPM composition. The high-frequency dynamics of ETMs are constrained by interactions with the low-frequency dynamics of the bottom pool of easily erodible sediments. Here, we use a transport decomposition to present processes that lead to convergent SPM transport, and review trapping mechanisms that lead to ETMs at the landward limit of the salt intrusion, in the freshwater zone, at topographic transitions, and by lateral processes within the cross section. We use model simulations of example estuaries to demonstrate the complex concurrence of ETM formation mechanisms. We also discuss how changes in SPM trapping mechanisms, often caused by direct human interference, can lead to the generation of hyperturbid estuaries.
Miller, Cherie V.; Weyers, Holly S.; Blazer, Vicki; Freeman, Mary E.
2006-01-01
Several classes of chemicals that are known or suspected contaminants were found in bed sediment in Rock Creek, including polyaromatic hydrocarbons (PAHs), phthalate esters, organochlorine pesticides, dioxins and furans, trace metals and metalloids (mercury, arsenic, cadmium, chromium, cobalt, copper, lead, nickel, silver, and zinc), and polychlorinated biphenyls (total PCBs and selected aroclors). Concentrations of many of these chemicals consistently exceeded threshold or chronic-effects guidelines for the protection of aquatic life and often exceeded probable effects levels (PELs). Exceedance of PELs was dependent on the amount of total organic carbon in the sediments. Concurrent with the collection of sediment-quality data, white sucker (Catostomus commersoni) were evaluated for gross-external and internal-organ anomalies, whole-body burdens of chemical contaminants, and gut contents to determine prey. The histopathology of internal tissues of white sucker was compared to contaminant levels in fish tissue and bed sediment. Gut contents were examined to determine preferential prey and thus potential pathways for the bioaccumulation of chemicals from bed sediments. Male and female fish were tested separately. Lesions and other necroses were observed in all fish collected during both years of sample collection, indicating that fish in Rock Creek have experienced some form of environmental stress. No direct cause and effect was determined for chemical exposure and compromised fish health, but a substantial weight of evidence indicates that white sucker, which are bottom-feeding fish and low-order consumers in Rock Creek, are experiencing some reduction in vitality, possibly due to immunosuppression. Abnormalities observed in gonads of both sexes of white sucker and observations of abnormal behavior during spawning indicated some interruption in reproductive success.
Miller, C.V.; Weyers, H.S.; Blazer, V.S.; Freeman, M.E.
2006-01-01
Several classes of chemicals that are known or suspected contaminants were found in bed sediment in Rock Creek, including polyaromatic hydrocarbons (PAHs), phthalate esters, organochlorine pesticides, dioxins and furans, trace metals and metalloids (mercury, arsenic, cadmium, chromium, cobalt, copper, lead, nickel, silver, and zinc), and polychlorinated biphenyls (total PCBs and selected aroclors). Concentrations of many of these chemicals consistently exceeded thresholdor chronic-effects guidelines for the protection of aquatic life and often exceeded probable effects levels (PELs). Exceedance of PELs was dependent on the amount of total organic carbon in the sediments. Concurrent with the collection of sediment-quality data, white sucker (Catostomus commersoni) were evaluated for gross-external and internal-organ anomalies, whole-body burdens of chemical contaminants, and gut contents to determine prey. The histopathology of internal tissues of white sucker was compared to contaminant levels in fish tissue and bed sediment. Gut contents were examined to determine preferential prey and thus potential pathways for the bioaccumulation of chemicals from bed sediments. Male and female fish were tested separately. Lesions and other necroses were observed in all fish collected during both years of sample collection, indicating that fish in Rock Creek have experienced some form of environmental stress. No direct cause and effect was determined for chemical exposure and compromised fish health, but a substantial weight of evidence indicates that white sucker, which are bottom-feeding fish and low-order consumers in Rock Creek, are experiencing some reduction in vitality, possibly due to immunosuppression. Abnormalities observed in gonads of both sexes of white sucker and observations of abnormal behavior during spawning indicated some interruption in reproductive success.
Tidal asymmetry in a funnel-shaped estuary with mixed semidiurnal tides
Gong, Wenping; Schuttelaars, Henk; Zhang, Heng
2016-05-01
results show that the FDA exhibits a predominant tendency of shorter duration of low water slack, favoring the landward transport of fine sediment. The FVA demonstrates prevailing ebb dominance in the study period, favoring the seaward transport of coarse sediment. This ebb dominance is primarily induced by the interaction among the residual flow and the tidal constituents. The external TDA in the ocean experiences distinct cyclic variations with positive asymmetry when semidiurnal tides dominate and negative asymmetry during the periods when diurnal tides dominate. The funnel shape of the HE is advantageous for the development of positive tidal asymmetry as the semidiurnal tides are more amplified than the diurnal tides. The effect of river flow can enhance the ebb dominance, while the baroclinic effect is more complex. The existence of channel and shoals favors the development of residual pattern with seaward flow (ebb dominance) in the channel and landward flow (flood dominance) at the shoal when the tides are strong (semidiurnal tides dominate) and the residual pattern with landward flow (flood dominance) in the channel and seaward flow (ebb dominance) at the shoal when the baroclinic effect is dominant (diurnal tides dominate).
Algal stabilisation of estuarine sediments
International Nuclear Information System (INIS)
1992-01-01
The presence of benthic microalgae can increase the stability of intertidal sediments and influence sediment fluxes within an estuarine environment. Therefore the relative importance of algal stabilisation needs to be understood to help predict the effects of a tidal barrage. The biogenic stabilisation of intertidal estuarine sediments by epipelic diatom films and the macrophyte Vaucheria was studied at three sites on the Severn Estuary. The cohesive strength meter (CSM) was developed to measure surface critical shear stress with varied algal density. A number of techniques have been used to determine the general in situ erodibility of cohesive estuarine sediments. The measurements of sediment shear strength and critical erosion velocity were investigated. Field experiments were undertaken to investigate the effect of algae on binding sediments, and a predictive method for the assessment of sediment stabilisation by algal binding was developed. (author)
Shallow stratigraphy of the Skagit River Delta, Washington, derived from sediment cores
Grossman, Eric E.; George, Douglas A.; Lam, Angela
2011-01-01
Sedimentologic analyses of 21 sediment cores, ranging from 0.4 to 9.6 m in length, reveal that the shallow geologic framework of the Skagit River Delta, western Washington, United States, has changed significantly since 1850. The cores collected from elevations of 3.94 to -2.41 m (relative to mean lower low water) along four cross-shore transects between the emergent marsh and delta front show relatively similar environmental changes across an area spanning ~75 km2. Offshore of the present North Fork Skagit River and South Fork Skagit River mouths where river discharge is focused by diked channels through the delta, the entire 5–7-km-wide tidal flats are covered with 1–2 m of cross-bedded medium-to-coarse sands. The bottoms of cores, collected in these areas are composed of mud. A sharp transition from mud to a cross-bedded sand unit indicates that the tidal flats changed abruptly from a calm environment to an energetic one. This is in stark contrast to the Martha's Bay tidal flats north of the Skagit Bay jetty that was completed in the 1940s to protect the newly constructed Swinomish Channel from flooding and sedimentation. North of the jetty, mud ranging from 1 to 2 m thick drapes a previously silt- and sand-rich tidal flat. The silty sand is a sediment facies that would be expected there where North Fork Skagit River sedimentation occurred prior to jetty emplacement. This report describes the compositional and textural properties of the sediment cores by using geophysical, photographic, x-radiography, and standard sediment grain-size and carbon-analytical methods. The findings help to characterize benthic habitat structure and sediment transport processes and the environmental changes that have occurred across the nearshore of the Skagit River Delta. The findings will be useful for quantifying changes to nearshore marine resources, including impacts resulting from diking, river-delta channelization, shoreline development, and natural variations in fluvial-sediment
Three-dimensional semi-idealized model for estuarine turbidity maxima in tidally dominated estuaries
Kumar, Mohit; Schuttelaars, Henk M.; Roos, Pieter C.
2017-01-01
We develop a three-dimensional idealized model that is specifically aimed at gaining insight in the physical mechanisms resulting in the formation of estuarine turbidity maxima in tidally dominated estuaries. First, the three-dimensional equations for water motion and suspended sediment
International Nuclear Information System (INIS)
Goulevitch, J.
1980-01-01
The lithology, stratigraphy and mineralization of the Kapalga Formation (South Alligator Group) is described from the Margaret Syncline in the Pine Creek area of the Northern Territory of Australia. An interdigitation of carbonaceous siltstones and mudstones, chert, ashstones and tuffaceous chert, greywacke, siltstone, mudstone and minor banded iron formation (b.i.f.) characterises the Formation. These rocks define a vertical facies transition between low energy sediments of the underlying Koolpin Formation, and high energy sediments of the overlying Burrell Creek Formation. This transition is interlayered with numerous ashstone-tuffaceous chert horizons which were deposited during the waning stage of Gerowie Tuff sedimentation. The boundary between the Kapalga Formation of the South Alligator Group and the Burrell Creek Formation of the Finniss River Group is strictly conformable in this part of the Pine Creek 'Geosyncline'. Relict devitrified shards have been recognised in the Gerowie Tuff in the Margaret Syncline and these observations along with whole-rock chemical analyses conclusively support claims by previous investigators that these rocks are volcanic derivatives. Base metal mineralization at Iron Blow and Mt. Bonnie occurs as massive, stratiform, sulphide-silicate-carbonate lodes. The deposits are at the same stratigraphic level towards the base of the Kapalga Formation and minor stratification parallel with bedding has been observed. These features, and the association of the lodes with mud-flow breccias, lead to the conclusion that the lodes are syngenetic in origin. Thermochemical consideration of the sulphide assemblages together with the temporal relationship between the mineralization and Gerowie Tuff point to diagenetic devitrification of the underlying tuffaceous rocks as the source of the mineralization. Recent publications of experimental data from reaction of seawater and volcanic glass provide information which supports this thesis, and
van Maanen, Barend; Coco, Giovanni; Bryan, Karin
2016-04-01
The evolution of tidal basins and estuaries in tropical and subtropical regions is often influenced by the presence of mangrove forests. These forests are amongst the most productive environments in the world and provide important ecosystem services. However, these intertidal habitats are also extremely vulnerable and are threatened by climate change impacts such as sea level rise. It is therefore of key importance to improve our understanding of how tidal systems occupied by mangrove vegetation respond to rising water levels. An ecomorphodynamic model was developed that simulates morphological change and mangrove forest evolution as a result of mutual feedbacks between physical and biological processes. The model accounts for the effects of mangrove trees on tidal flow patterns and sediment dynamics. Mangrove growth is in turn controlled by hydrodynamic conditions. Under stable water levels, model results indicate that mangrove trees enhance the initiation and branching of tidal channels, partly because the extra flow resistance in mangrove forests favours flow concentration, and thus sediment erosion in between vegetated areas. The landward expansion of the channels, on the other hand, is reduced. Model simulations including sea level rise suggest that mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone. While the sea level is rising, mangroves are migrating landward and the channel network tends to expand landward too. The presence of mangrove trees, however, was found to hinder both the branching and headward erosion of the landward expanding channels. Simulations are performed according to different sea level rise scenarios and with different tidal range conditions to assess which tidal environments are most vulnerable. Changes in the properties of the tidal channel networks are being examined as well. Overall, model results highlight the role of mangroves in driving the
Temporal record of Pu isotopes in inter-tidal sediments from the northeastern Irish Sea
Energy Technology Data Exchange (ETDEWEB)
Lindahl, Patric, E-mail: patriclindahl@yahoo.com [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Worsfold, Paul; Keith-Roach, Miranda [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Andersen, Morten B. [Bristol Isotope Group, School of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1RJ (United Kingdom); Kershaw, Peter; Leonard, Kins [The Centre for Environment, Fisheries and Aquaculture Science, Lowestoft Laboratory, Pakefield Road, Suffolk NR33 0HT (United Kingdom); Choi, Min-Seok [Division of Earth and Environmental Science, Korea Basic Science Institute, 113 Gwahangno, Yusung-gu, Daejon 305-333 (Korea, Republic of); Boust, Dominique [Laboratoire de Radioecologie, Institut de Radioprotection et de Surete Nucleaire, BP 10, 50130 Cherbourg-Octeville (France); Lesueur, Patrick [University of Caen Basse Normandie, M2C UMR CNRS 6143, 14000 Caen (France)
2011-11-01
A depth profile of {sup 239}Pu and {sup 240}Pu specific activities and isotope ratios was determined in an inter-tidal sediment core from the Esk Estuary in the northeastern Irish Sea. The study site has been impacted with plutonium through routine radionuclide discharges from the Sellafield nuclear reprocessing plant in Cumbria, NW England. A pronounced sub-surface maximum of {approx} 10 kBq kg{sup -1} was observed for {sup 239+240}Pu, corresponding to the peak in Pu discharge from Sellafield in 1973, with a decreasing trend with depth down to {approx} 0.04 kBq kg{sup -1} in the deeper layers. The depth profile of {sup 239+240}Pu specific activities together with results from gamma-ray spectrometry for {sup 137}Cs and {sup 241}Am was compared with reported releases from the Sellafield plant in order to estimate a reliable sediment chronology. The upper layers (1992 onwards) showed higher {sup 239+240}Pu specific activities than would be expected from the direct input of annual Sellafield discharges, indicating that the main input of Pu is from the time-integrated contaminated mud patch of the northeastern Irish Sea. The {sup 240}Pu/{sup 239}Pu atom ratios ranged from {approx} 0.03 in the deepest layers to > 0.20 in the sub-surface layers with an activity-weighted average of 0.181. The decreasing {sup 240}Pu/{sup 239}Pu atom ratio with depth reflects the changing nature of operations at the Sellafield plant from weapons-grade Pu production to reprocessing spent nuclear fuel with higher burn-up times in the late 1950s. In addition, recent annual {sup 240}Pu/{sup 239}Pu atom ratios in winkles collected during 2003-2008 from three stations along the Cumbrian coastline showed no significant spatial or temporal differences with an overall average of 0.204, which supports the hypothesis of diluted Pu input from the contaminated mud patch. - Highlights: {yields} Depth profiles of {sup 239}Pu and {sup 240}Pu determined in a northeastern Irish Sea sediment. {yields
Fletcher, C. H.; Knebel, H.J.; Kraft, J.C.
1992-01-01
The Holocene transgression of the Delaware Bay estuary and adjacent Atlantic coast results from the combined effect of regional crustal subsidence and eustasy. Together, the estuary and ocean coast constitute a small sedimentary basin whose principal depocenter has migrated with the transgression. A millenial time series of isopach and paleogeographic reconstructions for the migrating depocenter outlines the basin-wide pattern of sediment distribution and accumulation. Upland sediments entering the basin through the estuarine turbidity maximum accumulate in tidal wetland or open water sedimentary environments. Wind-wave activity at the edge of the tidal wetlands erodes the aggraded Holocene section and builds migrating washover barriers. Along the Atlantic and estuary coasts of Delaware, the area of the upland environment decreases from 2.0 billion m2 to 730 million m2 during the transgression. The area of the tidal wetland environment increases from 140 million to 270 million m2, and due to the widening of the estuary the area of open water increases from 190 million to 1.21 billion m2. Gross uncorrected rates of sediment accumulation for the tidal wetlands decrease from 0.64 mm/yr at 6 ka to 0.48 mm/yr at 1 ka. In the open water environments uncorrected rates decrease from 0.50 mm/yr to 0.04 mm/yr over the same period. We also present data on total sediment volumes within the tidal wetland and open water environments at specific intervals during the Holocene.
Eriksson, B.K.; van der Heide, T.; Van de Koppel, J.; Piersma, T.; Van der Veer, H.W.; Olff, H.
2010-01-01
Shallow soft-sediment systems are mostly dominated by species that, by strongly affecting sediment dynamics, modify their local environment. Such ecosystem engineering species can have either sediment-stabilizing or sediment-destabilizing effects on tidal flats. They interplay with abiotic forcing
Directory of Open Access Journals (Sweden)
Xiaoqin Du
2015-01-01
Full Text Available Espichel-Sines is an embayed coast in SW Portugal, consisting of two capes at both extremities, a tidal inlet and associated ebb tidal delta, a barrier spit, sandy beaches, sea cliffs, and a submarine canyon. Beach berm, backshore, near shore and inner shelf sediment samples were taken. Samples were analyzed for their grain-size compositions. This study ranks the hypothetical sediment sources influences on the sediment distributions in the study area using the multivariate Empirical Orthogonal Function (EOF techniques. Transport pathways in this study were independently identified using the grain size trend analysis (GSTA technique to verify the EOF findings. The results show that the cliff-erosion sediment is composed of pebbles and sand and is the most important sediment source for the entire embayment. The sediment at the inlet mouth is a mixture of pebbles, sand, silt, and clay, which is a minor sediment source that only has local influence. The overall grain-size distributions on the shelf are dominated by the sand except for the high mud content around the tidal delta front in the northern embayment. Sediment transport patterns on the inner shelf at the landward and north sides of the canyon head are landward and northward along the barrier spit, respectively. On the south side of the canyon head, the prevailing sediment transport is seaward. Sediment transport occurs in both directions along the shore.
Hyer, Kenneth E.; Denver, Judith M.; Langland, Michael J.; Webber, James S.; Böhlke, J.K.; Hively, W. Dean; Clune, John W.
2016-11-17
these conservation practices detected in Smith Creek will depend largely on whether nutrient loading (of manure and commercial fertilizer) is reduced over time.Upper Chester RiverThe Upper Chester River watershed includes the 36-square-mile (mi2) watershed area around several nontidal tributaries that drain into the tidal Chester River. The streamgage is on Chesterville Branch, the largest nontidal tributary (approximately 6.12 mi2) and is the site for continuous water-quality monitoring for this project. The base-flow index at Chesterville Branch is about 72 percent and indicates that, as in most of the Coastal Plain, groundwater is the greatest contributor to streamflow. As such, more than 90 percent of the nitrogen in the stream is in the form of nitrate from groundwater. Continuous and discrete data collected at Chesterville Branch show the effects of streamflow and season on water quality. Significantly positive correlations with flow were observed for ammonium, dissolved and total phosphorus, sediment, and turbidity as runoff carried these constituents from the land surface into Chesterville Branch. Other constituents that increased significantly with flow include potassium, sulfate, iron, and manganese, which are likely contributed from near-stream areas and ponds with high organic-matter content. Total nitrogen, pH, and specific conductance, along with chemical constituents associated with groundwater inputs including nitrate, calcium, ratio of calcium to magnesium, silica, bicarbonate, and sodium, were negatively correlated with flow because concentrations of these constituents were diluted by runoff.Seasonal differences in water chemistry, which are most likely related to increased biologic effects on the uptake and release of chemicals in the stream and near-stream areas, also were observed. Water temperature, orthophosphate, δ15N of nitrate, bicarbonate, sodium, and the ratio of sodium to chloride were higher during the warm season, and dissolved oxygen
van Maanen, B.; Coco, G.; Bryan, K. R.
2015-01-01
An ecomorphodynamic model was developed to study how Avicennia marina mangroves influence channel network evolution in sandy tidal embayments. The model accounts for the effects of mangrove trees on tidal flow patterns and sediment dynamics. Mangrove growth is in turn controlled by hydrodynamic conditions. The presence of mangroves was found to enhance the initiation and branching of tidal channels, partly because the extra flow resistance in mangrove forests favours flow concentration, and thus sediment erosion in between vegetated areas. The enhanced branching of channels is also the result of a vegetation-induced increase in erosion threshold. On the other hand, this reduction in bed erodibility, together with the soil expansion driven by organic matter production, reduces the landward expansion of channels. The ongoing accretion in mangrove forests ultimately drives a reduction in tidal prism and an overall retreat of the channel network. During sea-level rise, mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone, while hindering both the branching and headward erosion of the landward expanding channels. The modelling results presented here indicate the critical control exerted by ecogeomorphological interactions in driving landscape evolution. PMID:26339195
International Nuclear Information System (INIS)
Shutz, D.J.
1989-01-01
On an annual basis, river supplied nitrate is the predominant form of N supplied to the tidal Potomac River from external sources. Much of the nitrate is associated with high flows that have rapid transit times through the tidal river. After the fall of 1980, initiation of advanced wastewater treatment at the Blue Plains Sewage Treatment Plant (STPP) reduced ammonia loading to the river by 90% and increased nitrate loading by a similar percentage. As a result, concentrations of ammonia during the 1981 low flow period were 1.50 mg/L as N. Despite the reduced availability of ammonia, 15-N uptake studies showed that phytoplankton preferred ammonia to nitrate unless ammonia concentrations were < 0.10 mg/L as N. Nitrification studies during 1981 using a 14-C uptake technique indicate that rates did not vary with sample location, except for one sample from the head of the tidal river, where the rates were much higher. Process models were used in conjunction with mass-balance determinations and individual process studies to estimate rates of processes that were not directly measured. It is estimated that denitrification removed 10 times as much nitrate from the water column during the summer of 1981 as during the summer of 1980. Sedimentation of particulate N is estimated to be the largest sink for N from the water column and was approximately equal to the external annual loading of all N constituents on a daily basis. In summer, when river flows usually are low, the tidal Potomac River appears to be a partially closed system rather than one dominated by transport. Nitrogen constituents, primarily from point sources, are taken up by phytoplankton converted to organic matter, and sedimented from the water column. Some of this N eventually becomes available again by means of benthic exchange. Removal, by transport, out of the tidal river is significant only during winter. 70 refs., 20 figs., 10 tabs
2018-01-11
sediments (oozes and clays) CJ is set to 2.5x10- 3 as a default roughness. Relative sediment density s = 1.722 (dry bulk density by mass of sand , Rijn...dso and relative density s for each sediment type used in the calculation of CJ Sediment Type Gravel and coarser Sand Silt Ash and volcanic sand ...FUGAWI navigational charts allowed the tidal elevation to reach close to the measured M2 amplitude. Clearly, greater availability and quality of
Sedimentary structures of tidal flats: A journey from coast to inner ...
Indian Academy of Sciences (India)
defined by the time available to move water masses. This, in turn, affects the development of sedi- mentary structures as well as the distribution of organisms in the intertidal zone and therefore, the animal-sediment relationship. Ever since the systematic study for the identi- fication of tidal flat environment in rock records.
Kleinhans, Maarten; Braat, Lisanne; Leuven, Jasper; Baar, Anne; van der Vegt, Maarten; van Maarseveen, Marcel; Markies, Henk; Roosendaal, Chris; van Eijk, Arjan
2016-04-01
Many estuaries formed over the Holocene through a combination of fluvial and coastal influxes, but how estuary planform shape and size depend on tides, wave climate and river influxes remains unclear. Here we use a novel tidal flume setup of 20 m length by 3 m width, the Metronome (http://www.uu.nl/metronome), to create estuaries and explore a parameter space for the simple initial condition of a straight river in sandy substrate. Tidal currents capable of transporting sediment in both the ebb and flood phase because they are caused by periodic tilting of the flume rather than the classic method of water level fluctuation. Particle imaging velocimetry and a 1D shallow flow model demonstrate that this principle leads to similar sediment mobility as in nature. Ten landscape experiments recorded by timelapse overhead imaging and AGIsoft DEMs of the final bed elevation show that absence of river inflow leads to short tidal basins whereas even a minor discharge leads to long convergent estuaries. Estuary width and length as well as morphological time scale over thousands of tidal cycles strongly depend on tidal current amplitude. Paddle-generated waves subdue the ebb delta causing stronger tidal currents in the basin. Bar length-width ratios in estuaries are slightly larger to those in braided rivers in experiments and nature. Mutually evasive ebb- and flood-dominated channels are ubiquitous and appear to be formed by an instability mechanism with growing bar and bifurcation asymmetry. Future experiments will include mud flats and live vegetation.
Which future for the tidal sector in France? Towards a new model of territorial development
International Nuclear Information System (INIS)
Aelbrecht, Denis; Deroo, Luc; Le Visage, Christophe; Rabain, Antoine
2017-01-01
This document proposes a brief overview of works by a French national work-group of the SHF (French Hydro-technical Society) on the new tidal sector. It indicates recent and current development in the renewable marine energy sector: offshore wind farms along the French coasts, floating wind energy demonstrators, several tidal stream demonstrators, and other projects. British projects are also evoked. Then various aspects which could be success factors, are briefly discussed: the tidal potential, project configuration types (dams in estuary, coastal lagoons, offshore lagoons), interactions with the environment (sea and coastal ecosystems, sediments), opportunities of technological innovation (belt of the tidal basin, machine technology, exploitation mode), the concept of tidal garden, economic performance and viability (orientations for cost reduction and income increase). The issue of feasibility with respect with the NIMBY syndrome is finally addressed, and orientations and principles are briefly defined to evolve towards a YINBY (Yes in my back yard) syndrome
An Introduction to the San Francisco Estuary Tidal Wetlands Restoration Series
Directory of Open Access Journals (Sweden)
Larry R. Brown
2003-10-01
Full Text Available Restoration of tidal wetlands may provide an important tool for improving ecological health and water management for beneficial uses of the San Francisco Estuary (hereafter “Estuary”. Given the large losses of tidal wetlands from San Francisco Bay and the Sacramento-San Joaquin Delta in the last 150 years, it seems logical to assume that restoring tidal wetlands will have benefits for a variety of aquatic and terrestrial native species that have declined during the same time period. However, many other changes have also occurred in the Estuary concurrent with the declines of native species. Other factors that might be important in species declines include the effects of construction of upstream dams, large and small water diversions within the Sacramento-San Joaquin Delta, agricultural pesticides, trace elements from industrial and agricultural activities, and invasions of alien species. Discussions among researchers, managers, and stakeholders have identified a number of uncertainties regarding the potential benefits of tidal wetland restoration. The articles of the Tidal Wetlands Restoration Series address four major issues of concern. Stated as questions, these are: 1. Will tidal wetland restoration enhance populations of native fishes? 2. Will wetland restoration increase rates of methylation of mercury? 3. Will primary production and other ecological processes in restored tidal wetlands result in net export of organic carbon to adjacent habitats, resulting in enhancement of the food web? Will the carbon produced contribute to the formation of disinfection byproducts when disinfected for use as drinking water? 4. Will restored tidal wetlands provide long-term ecosystem benefits that can be sustained in response to ongoing physical processes, including sedimentation and hydrodynamics? Reducing the uncertainty surrounding these issues is of critical importance because tidal wetland restoration is assumed to be a critical tool for
Channel incision and suspended sediment delivery at Caspar Creek, Mendocino County, California
Nicholas J. Dewey; Thomas E. Lisle; Leslie M. Reid
2003-01-01
Tributary and headwater valleys in the Caspar Creek watershed,in coastal Mendocino County, California,show signs of incision along much of their lengths.An episode of incision followed initial-entry logging which took place between 1860 and 1906. Another episode of incision cut into skid-trails created for second-entry logging in the 1970's.
Sediment Flux and Storage in a Rural Southeastern Piedmont River System
Jackson, C. R.; Martin, J. K.
2001-12-01
A sediment budget was developed for a representative rural southeastern Piedmont watershed to provide information on the relative importance of sediment sources. Sediment issues in the southeastern Piedmont are complicated by the so-called legacy sediment produced by poor farming practices during the cotton-farming era, approximately 1810-1930. The Murder Creek basin near Monticello, GA was chosen because: it featured forestry and agriculture as the principal land uses; a USGS gage provided a flow record; and the creek deposited in a reservoir built in 1948. Suspended load export was calculated using a sediment rating curve and the USGS flow time series. Bed load export was determined by estimating the volume of sediment deposited in the reservoir since construction. Unpaved road erosion was estimated using the WEPP model, and other surface erosion was estimated using USLE and delivery ratios. Historical floodplain storage was determined by coring floodplain deposits, measuring the depth to the pre-historic/historic sediment interface, and multiplying by the area of the floodplain. Recent accretion rates were estimated using dendrogeomorphology. Results showed that the practices of the cotton farming era deposited an average of 1.6 meters of sediment on the floodplains. This depth was relatively uniform across the watershed. The cotton-farming sediment in storage exceeds the current annual export by a factor of about 5000. Approximately half of the current export comes from current inputs, and half comes from remobilized floodplain sediments.
Evidence of tidal processes from the lower part of the Witwatersrand Supergroup, South Africa
Eriksson, Kenneth A.; Turner, Brian R.; Vos, Richard G.
1981-08-01
A 1600-m succession of quartz arenites and associated shaley deposits comprising the Hospital Hill Subgroup at the base of the Witwatersrand Supergroup is considered to have been deposited largely under the influence of tidal processes. Facies analysis indicates that deposition occurred in the following environments: (1) marine shalf; (2) shallow subtidal to intertidal; (3) intertidal flat; and (4) tidal inlet. The presence of strong tidal currents implies that the Witwatersrand Basin was open to an ocean basin, at least during the early stages of its evolution. Palaeocurrent trends and isopach data suggest that this probably lay to the southwest, an area now occupied by the high grade Natal—Namaqua metamorphic belt. The contrast between the supermature quartz arenites of the Hospital Hill Subgroup and the overlying gold-bearing immature subgreywackes, feldspathic quartzites and conglomerates of fluvial origin is believed to be a function of tidal reworking of sediments.
Directory of Open Access Journals (Sweden)
J. M. Holstein
2010-11-01
Full Text Available The redox succession in shallow marine sediments generally exhibits a predictable pattern. Pore water profiles from a back barrier tidal flat in the German Wadden Sea depart from the expected redox zoning. Instead, a sulfate minimum zone associated with a sulfate-methane-sulfate double interface and a distinct ammonium peak at 1.5 m below sea floor (mbsf is displayed. Such evidence for significant degradation of organic matter (OM in subsurface layers is challenging our understanding of tidal flat biogeochemistry as little is known about processes that relocate reactive OM into layers far distant from the sediment-water interface. The objectives of our model study were to identify possible mechanisms for the rapid transport of organic matter to subsurface layers that cause the reversed redox succession and to constrain several important biogeochemical control parameters. We compared two scenarios for OM transfer: rapid sedimentation and burial of OM as well as lateral advection of suspended POM. Using a diagenetic model, uncertain process parameters, in particular those connected to OM degradation and (vertical or lateral transport, are systematically calibrated using field data.
We found that both scenarios, advection and sedimentation, had solutions consistent with the observed pore water profiles. For this specific site, however, advective transport of particulate material had to be rejected since the reconstructed boundary conditions were rather improbable. In the alternative deposition set-up, model simulations suggested the deposition of the source OM about 60 yrs before cores were taken. A mean sedimentation rate of approximately 2 cm yr−1 indicates substantial changes in near coast tidal flat morphology, since sea level rise is at a much lower pace. High sedimentation rates most probably reflect the progradation of flats within the study area. These or similar morphodynamic features also occur in other coastal areas
Comparison of HSPF and SWAT models performance for runoff and sediment yield prediction.
Im, Sangjun; Brannan, Kevin M; Mostaghimi, Saied; Kim, Sang Min
2007-09-01
A watershed model can be used to better understand the relationship between land use activities and hydrologic/water quality processes that occur within a watershed. The physically based, distributed parameter model (SWAT) and a conceptual, lumped parameter model (HSPF), were selected and their performance were compared in simulating runoff and sediment yields from the Polecat Creek watershed in Virginia, which is 12,048 ha in size. A monitoring project was conducted in Polecat Creek watershed during the period of October 1994 to June 2000. The observed data (stream flow and sediment yield) from the monitoring project was used in the calibration/validations of the models. The period of September 1996 to June 2000 was used for the calibration and October 1994 to December 1995 was used for the validation of the models. The outputs from the models were compared to the observed data at several sub-watershed outlets and at the watershed outlet of the Polecat Creek watershed. The results indicated that both models were generally able to simulate stream flow and sediment yields well during both the calibration/validation periods. For annual and monthly loads, HSPF simulated hydrologic and sediment yield more accurately than SWAT at all monitoring sites within the watershed. The results of this study indicate that both the SWAT and HSPF watershed models performed sufficiently well in the simulation of stream flow and sediment yield with HSPF performing moderately better than SWAT for simulation time-steps greater than a month.
Tidal Venuses: triggering a climate catastrophe via tidal heating.
Barnes, Rory; Mullins, Kristina; Goldblatt, Colin; Meadows, Victoria S; Kasting, James F; Heller, René
2013-03-01
Traditionally, stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here, we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at high-enough levels to induce a runaway greenhouse for a long-enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets "Tidal Venuses" and the phenomenon a "tidal greenhouse." Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits (i.e., with negligible tidal heating) in the habitable zone (HZ). However, these planets are not habitable, as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with massesplanet orbiting a 0.3 MSun star at 0.12 AU. We found that it probably did not lose its water via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories.
Conceptual Site Model for Newark Bay—Hydrodynamics and Sediment Transport
Directory of Open Access Journals (Sweden)
Parmeshwar L. Shrestha
2014-02-01
Full Text Available A conceptual site model (CSM has been developed for the Newark Bay Study Area (NBSA as part of the Remedial Investigation/Feasibility Study (RI/FS for this New Jersey site. The CSM is an evolving document that describes the influence of physical, chemical and biological processes on contaminant fate and transport. The CSM is initiated at the start of a project, updated during site activities, and used to inform sampling and remediation planning. This paper describes the hydrodynamic and sediment transport components of the CSM for the NBSA. Hydrodynamic processes are influenced by freshwater inflows, astronomical forcing through two tidal straits, meteorological conditions, and anthropogenic activities such as navigational dredging. Sediment dynamics are driven by hydrodynamics, waves, sediment loading from freshwater sources and the tidal straits, sediment size gradation, sediment bed properties, and particle-to-particle interactions. Cohesive sediment transport is governed by advection, dispersion, aggregation, settling, consolidation, and erosion. Noncohesive sediment transport is governed by advection, dispersion, settling, armoring, and transport in suspension and along the bed. The CSM will inform the development and application of a numerical model that accounts for all key variables to adequately describe the NBSA’s historical, current, and future physical conditions.
Sediment characteristics at intertidal regions across Yarada beach, East coast of India
Digital Repository Service at National Institute of Oceanography (India)
Yadhunath, E.M.; Raju, N.S.N.; Ganesan, P.; Gowthaman, R.; JayaKumar, S.
Sediment samples were collected once a month at five different inter-tidal zones across Yarada beach during May-2009 to May-2010 These sediments are characterized by bimodal and unimodal behaviour and most of them are sorted as moderately as well...
Comparing geological and statistical approaches for element selection in sediment tracing research
Laceby, J. Patrick; McMahon, Joe; Evrard, Olivier; Olley, Jon
2015-04-01
Elevated suspended sediment loads reduce reservoir capacity and significantly increase the cost of operating water treatment infrastructure, making the management of sediment supply to reservoirs of increasingly importance. Sediment fingerprinting techniques can be used to determine the relative contributions of different sources of sediment accumulating in reservoirs. The objective of this research is to compare geological and statistical approaches to element selection for sediment fingerprinting modelling. Time-integrated samplers (n=45) were used to obtain source samples from four major subcatchments flowing into the Baroon Pocket Dam in South East Queensland, Australia. The geochemistry of potential sources were compared to the geochemistry of sediment cores (n=12) sampled in the reservoir. The geochemical approach selected elements for modelling that provided expected, observed and statistical discrimination between sediment sources. Two statistical approaches selected elements for modelling with the Kruskal-Wallis H-test and Discriminatory Function Analysis (DFA). In particular, two different significance levels (0.05 & 0.35) for the DFA were included to investigate the importance of element selection on modelling results. A distribution model determined the relative contributions of different sources to sediment sampled in the Baroon Pocket Dam. Elemental discrimination was expected between one subcatchment (Obi Obi Creek) and the remaining subcatchments (Lexys, Falls and Bridge Creek). Six major elements were expected to provide discrimination. Of these six, only Fe2O3 and SiO2 provided expected, observed and statistical discrimination. Modelling results with this geological approach indicated 36% (+/- 9%) of sediment sampled in the reservoir cores were from mafic-derived sources and 64% (+/- 9%) were from felsic-derived sources. The geological and the first statistical approach (DFA0.05) differed by only 1% (σ 5%) for 5 out of 6 model groupings with only
Removal and distribution of iodate in mangrove environment
International Nuclear Information System (INIS)
Machado, E.C; Machado, W; Sanders, L.F; Bellido, L.F; Patchineelam, S.R; Bellido Jr, A.V
2003-01-01
Retention experiments were carried out in laboratory in order to investigate the iodate ion removal from tidal water by the underlying creek sediment, as well as, distribution in the mangrove sediment of Sepetiba Bay, Rio de Janeiro. Local tidal water spiked with 131 IO 3 was added to several cores containing 6-7 cm of mangrove sediment. A sample solution was taken everyday for 8□9 days and assayed by means of a high purity germanium detector coupled to a multichannel analyser. It was found that, after two days, around 56 % of the radioiodate was taken up by the sediment. At the end of the experiment, the sediment was sectioned in 1-cm layers and also analyzed by gamma spectrometry. The overall results, in seven cores, showed that 89% of initial 131 IO 3 activities were transferred to sediment, whereas 78% of the total activity was within the first cm of the upper layer. It seems from the determination of total organic matter content, that the organic matter present in the Sepetiba's mangrove sediment, have a substantial influence in the iodate removal from the water column (author)
Sparks, G. C.; Alpers, C. N.; Horner, T. C.; Cornwell, K.; Izzo, V.
2016-12-01
The relative contributions of total mercury (THg) and methylmercury (MeHg) from upstream historical mercury (Hg) mining districts were examined in the three largest tributaries to Lake Berryessa, a reservoir with water quality impaired by Hg. A fish consumption advisory has been issued for the reservoir; also, in a study of piscivorous birds at 25 California reservoirs, blood samples from Lake Berryessa grebes had the highest THg concentration state-wide. The third and fourth largest historical Hg-producing mining districts in California are within the study area. These mining districts are located within the Pope Creek, Upper Putah Creek, and Knoxville-Eticuera Creeks watersheds. Downstream of the reservoir, Lower Putah Creek drains into the Yolo Bypass, a major source of THg and MeHg to the Sacramento-San Joaquin Delta. Study objectives included: (1) determining if tributaries downstream of historical Hg mining districts and draining to the reservoir are continuing sources of THg and MeHg; (2) characterizing variability of water and streambed sediment parameters in upstream and downstream reaches of each creek; and (3) estimating loads of suspended sediment, THg, and MeHg entering the reservoir from each tributary. Water samples were collected from October 2012 to September 2014 during non-storm and storm events along each tributary and analyzed for general water quality field parameters; unfiltered THg and MeHg; total suspended solids; and total particulate matter. Discharge measurements were made at the time of sample collection; flow and concentration data were combined to compute daily loads. To determine spatial variability, 135 streambed sediment samples were analyzed for THg, organic content (loss on ignition), and grain-size distribution. All three tributaries contribute THg and MeHg to the reservoir. Some consistent spatial trends in THg (water) concentrations were observed over multiple sampling events; THg (water) decreased from upstream to downstream
Lara A. Martin; Patrick J. Mulholland; Jackson R. Webster; H. Maurice Vallett
2001-01-01
We investigated variations in resource availability (NOa-N and labile organic C [LOCJ] as determinants of potential denitrification in stream sediments in the southern Appalachian Mountains, USA. stream-water and sediments were sampled seasonally in 2 streams of contrasting NO3,-N availability, Noland Creek (high NO
Short-term tidal asymmetry inversion in a macrotidal estuary (Beira, Mozambique)
Nzualo, Teodósio N. M.; Gallo, Marcos N.; Vinzon, Susana B.
2018-05-01
observed. While fortnightly inversion in the tidal duration asymmetry is explained by the presence of channels and sandbanks, at the same time, the tidal velocity asymmetry acts as a positive feedback mechanism for bank formation and sediment retention.
Wilson, Jennifer T.
2011-01-01
Elevated concentrations of sediment-associated contaminants are typically associated with urban areas such as San Antonio, Texas, in Bexar County, the seventh most populous city in the United States. This report describes an assessment of selected sediment-associated contaminants in samples collected in Bexar County from sites on the following streams: Medio Creek, Medina River, Elm Creek, Martinez Creek, Chupaderas Creek, Leon Creek, Salado Creek, and San Antonio River. During 2007-09, the U.S. Geological Survey periodically collected surficial streambed-sediment samples during base flow and suspended-sediment (large-volume suspended-sediment) samples from selected streams during stormwater runoff. All sediment samples were analyzed for major and trace elements and for organic compounds including halogenated organic compounds and polycyclic aromatic hydrocarbons (PAHs). Selected contaminants in streambed and suspended sediments in watersheds of the eight major streams in Bexar County were assessed by using a variety of methods—observations of occurrence and distribution, comparison to sediment-quality guidelines and data from previous studies, statistical analyses, and source indicators. Trace elements concentrations were low compared to the consensus-based sediment-quality guidelines threshold effect concentration (TEC) and probable effect concentration (PEC). Trace element concentrations were greater than the TEC in 28 percent of the samples and greater than the PEC in 1.5 percent of the samples. Chromium concentrations exceeded sediment-quality guidelines more frequently than concentrations of any other constituents analyzed in this study (greater than the TEC in 69 percent of samples and greater than the PEC in 8 percent of samples). Mean trace element concentrations generally are lower in Bexar County samples compared to concentrations in samples collected during previous studies in the Austin and Fort Worth, Texas, areas, but considering the relatively
Wiley, J.B.
1994-01-01
The U.S. Geological Survey, in cooperation with the National Park Service, studied the frequency and magnitude of flooding near the mouths of five tributaries to the New River in the New River Gorge National River. The 100-year peak discharge at each tributary was determined from regional frequency equations. The 100-year discharge at Wolf Creek, Craig Branch, Manns Creek, Dunloup Creek, and Mill Creek was 3,400 cubic feet per second, 640 cubic feet per second, 8,200 cubic feet per second, 7,100 cubic feet per second, and 9,400 cubic feet per second, respectively. Flood elevations for each tributary were determined by application of a steady-state, one-dimensional flow model. Manning's roughness coefficients for the stream channels ranged from 0.040 to 0.100. Bridges that would be unable to contain the 100-year flood within the bridge opening included: the State Highway 82 bridge on Wolf Creek, the second Fayette County Highway 25 bridge upstream from the confluence with New River on Dunloup Creek, and an abandoned log bridge on Mill Creek.
Prehospital tidal volume influences hospital tidal volume: A cohort study.
Stoltze, Andrew J; Wong, Terrence S; Harland, Karisa K; Ahmed, Azeemuddin; Fuller, Brian M; Mohr, Nicholas M
2015-06-01
The purposes of the study are to describe current practice of ventilation in a modern air medical system and to measure the association of ventilation strategy with subsequent ventilator care and acute respiratory distress syndrome (ARDS). Retrospective observational cohort study of intubated adult patients (n = 235) transported by a university-affiliated air medical transport service to a 711-bed tertiary academic center between July 2011 and May 2013. Low tidal volume ventilation was defined as tidal volumes less than or equal to 8 mL/kg predicted body weight. Multivariable regression was used to measure the association between prehospital tidal volume, hospital ventilation strategy, and ARDS. Most patients (57%) were ventilated solely with bag valve ventilation during transport. Mean tidal volume of mechanically ventilated patients was 8.6 mL/kg predicted body weight (SD, 0.2 mL/kg). Low tidal volume ventilation was used in 13% of patients. Patients receiving low tidal volume ventilation during air medical transport were more likely to receive low tidal volume ventilation in the emergency department (P tidal volume (P = .840). Low tidal volume ventilation was rare during air medical transport. Air transport ventilation strategy influenced subsequent ventilation but was not associated with ARDS. Copyright © 2015 Elsevier Inc. All rights reserved.
Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating
Mullins, Kristina; Goldblatt, Colin; Meadows, Victoria S.; Kasting, James F.; Heller, René
2013-01-01
Abstract Traditionally, stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here, we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at high-enough levels to induce a runaway greenhouse for a long-enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets “Tidal Venuses” and the phenomenon a “tidal greenhouse.” Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits (i.e., with negligible tidal heating) in the habitable zone (HZ). However, these planets are not habitable, as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with massestidal heating. We have applied these concepts to Gl 667C c, a ∼4.5 MEarth planet orbiting a 0.3 MSun star at 0.12 AU. We found that it probably did not lose its water via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories. Key Words: Extrasolar terrestrial planets—Habitability—Habitable zone
Storm water control plan for the Lower East Fork Poplar Creek Operable Unit, Oak Ridge, Tennessee
International Nuclear Information System (INIS)
1996-04-01
This document provides the Environmental Restoration Program with information about the erosion and sediment control, storm water management, maintenance, and reporting and record keeping practices to be employed during Phase II of the remediation project for the Lower East Fork Poplar Creek (LEFPC) Operable Unit
Waddell, Kidd M.; Darby, D.W.; Theobald, S.M.
1985-01-01
Evaluations based on the nutrient content of the inflow, outflow, water in storage, and the dissolved-oxygen depletion during the summer indicate that the trophic state of Scofield Reservoir is borderline between mesotrophic and eutrophic and may become highly eutrophic unless corrective measures are taken to limit nutrient inflow.Sediment deposition in Scofield Reservoir during 1943-79 is estimated to be 3,000 acre-feet, and has decreased the original storage capacity of the reservoir by 4 percent. The sediment contains some coal, and age dating of those sediments (based on the radioisotope lead-210) indicates that most of the coal was deposited prior to about 1950.Scofield Reservoir is dimictic, with turnovers occurring in the spring and autumn. Water in the reservoir circulates completely to the bottom during turnovers. The concentration of dissolved oxygen decreases with depth except during parts of the turnover periods. Below an altitude of about 7,590 feet, where 20 percent of the water is stored, the concentration of dissolved oxygen was less than 2 milligrams per liter during most of the year. During the summer stratification period, the depletion of dissolved oxygen in the deeper layers is coincident with supersaturated conditions in the shallow layers; this is attributed to plant photosynthesis and bacterial respiration in the reservoir.During October 1,1979-August 31,1980, thedischargeweighted average concentrations of dissolved solids was 195 milligrams per liter in the combined inflow from Fish, Pondtown, and Mud Creeks, and was 175 milligrams per liter in the outflow (and to the Price River). The smaller concentration in the outflow was due primarily to precipitation of calcium carbonate in the reservoir about 80 percent of the decrease can be accounted for through loss as calcium carbonate.The estimated discharge-weighted average concentration of total nitrogen (dissolved plus suspended) in the combined inflow of Fish, Pondtown, and Mud Creeks was 1
Ockerman, Darwin J.; Fernandez, Carlos J.
2010-01-01
The U.S. Geological Survey, in cooperation with the Texas State Soil and Water Conservation Board, Coastal Bend Bays and Estuaries Program, and Texas AgriLife Research and Extension Center at Corpus Christi, studied hydrologic conditions and water quality of rainfall and storm runoff of two primarily agricultural subwatersheds of the Oso Creek watershed in Nueces County, Texas. One area, the upper West Oso Creek subwatershed, is about 5,145 acres. The other area, a subwatershed drained by an unnamed tributary to Oso Creek (hereinafter, Oso Creek tributary), is about 5,287 acres. Rainfall and runoff (streamflow) were continuously monitored at the outlets of the two subwatersheds during the study period October 2005-September 2008. Seventeen rainfall samples were collected and analyzed for nutrients and major inorganic ions. Twenty-four composite runoff water-quality samples (12 at West Oso Creek, 12 at Oso Creek tributary) were collected and analyzed for nutrients, major inorganic ions, and pesticides. Twenty-six discrete suspended-sediment samples (12 West Oso Creek, 14 Oso Creek tributary) and 17 bacteria samples (10 West Oso Creek, 7 Oso Creek tributary) were collected and analyzed. These data were used to estimate, for selected constituents, rainfall deposition to and runoff loads and yields from the two subwatersheds. Quantities of fertilizers and pesticides applied in the two subwatersheds were compared with quantities of nutrients and pesticides in rainfall and runoff. For the study period, total rainfall was greater than average. Most of the runoff from the two subwatersheds occurred in response to a few specific storm periods. The West Oso Creek subwatershed produced more runoff during the study period than the Oso Creek tributary subwatershed, 13.95 inches compared with 9.45 inches. Runoff response was quicker and peak flows were higher in the West Oso Creek subwatershed than in the Oso Creek tributary subwatershed. Total nitrogen runoff yield for the 3
Lithologic Coring in the Lower Anacostia Tidal Watershed, Washington, D.C., July 2002
Tenbus, Frederick J.
2003-01-01
Little is known about the volumetric flux of ground water to the lower tidal Anacostia River, or whether ground-water flow is an important component of the contaminant load in this part of the Anacostia River. The watershed is in the eastern part of Washington, D.C., and has been subjected to over 200 years of urbanization and modifications of the river channel and nearby land areas. These anthropogenic factors, along with tidal fluctuations in the river, make ground-water data collection and interpretations difficult. The U.S. Geological Survey is cooperating with the District of Columbia Department of Health, Environmental Health Administration, Bureau of Environmental Quality, Water Quality Division, in a study to assess nonpoint-source pollution from ground water into the lower tidal Anacostia River. Lithologic cores from drilling activities conducted during July 2002 in the study area have been interpreted in the context of geologic and hydrogeologic information from previous studies in the lower Anacostia tidal watershed. These interpretations can help achieve the overall project goals of characterizing ground-water flow and contaminant load in the study area. Hydrostratigraphic units encountered during drilling generally consisted of late Pleistocene to Holocene fluvial deposits overlying Cretaceous fluvial/deltaic deposits. Cores collected in Beaverdam Creek and the Anacostia River indicated high- and low-energy environments of deposition, respectively. Two cores collected near the river showed different types of anthropogenic fill underlain by low-energy deposits, which were in turn underlain by sand and gravel. A third core collected near the river consisted primarily of sand and gravel with no artificial fill.
Ambient Noise in an Urbanized Tidal Channel
Bassett, Christopher
In coastal environments, when topographic and bathymetric constrictions are combined with large tidal amplitudes, strong currents (> 2 m/s) can occur. Because such environments are relatively rare and difficult to study, until recently, they have received little attention from the scientific community. However, in recent years, interest in developing tidal hydrokinetic power projects in these environments has motivated studies to improve this understanding. In order to support an analysis of the acoustic effects of tidal power generation, a multi-year study was conducted at a proposed project site in Puget Sound (WA) are analyzed at a site where peak currents exceeded 3.5 m/s. From these analyses, three noise sources are shown to dominate the observed variability in ambient noise between 0.02-30 kHz: anthropogenic noise from vessel traffic, sediment-generated noise during periods of strong currents, and flow-noise resulting from turbulence advected over the hydrophones. To assess the contribution of vessel traffic noise, one calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site in northern Admiralty Inlet. The variability in spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband and M-weighted sound pressure levels is driven largely by vessel traffic. Within the one-year study period, at least one AIS transmitting vessel is present in the study area 90% of the time and over 1,363 unique vessels are recorded. A noise budget for vessels equipped with AIS transponders identifies cargo ships, tugs, and passenger vessels as the largest contributors to noise levels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessel types yields a cumulative probability density function of broadband sound pressure
Estuarine Sediment Deposition during Wetland Restoration: A GIS and Remote Sensing Modeling Approach
Newcomer, Michelle; Kuss, Amber; Kentron, Tyler; Remar, Alex; Choksi, Vivek; Skiles, J. W.
2011-01-01
Restoration of the industrial salt flats in the San Francisco Bay, California is an ongoing wetland rehabilitation project. Remote sensing maps of suspended sediment concentration, and other GIS predictor variables were used to model sediment deposition within these recently restored ponds. Suspended sediment concentrations were calibrated to reflectance values from Landsat TM 5 and ASTER using three statistical techniques -- linear regression, multivariate regression, and an Artificial Neural Network (ANN), to map suspended sediment concentrations. Multivariate and ANN regressions using ASTER proved to be the most accurate methods, yielding r2 values of 0.88 and 0.87, respectively. Predictor variables such as sediment grain size and tidal frequency were used in the Marsh Sedimentation (MARSED) model for predicting deposition rates for three years. MARSED results for a fully restored pond show a root mean square deviation (RMSD) of 66.8 mm (<1) between modeled and field observations. This model was further applied to a pond breached in November 2010 and indicated that the recently breached pond will reach equilibrium levels after 60 months of tidal inundation.
Fleck, Jacob A.; Alpers, Charles N.; Marvin-DiPasquale, Mark; Hothem, Roger L.; Wright, Scott A.; Ellett, Kevin; Beaulieu, Elizabeth; Agee, Jennifer L.; Kakouros, Evangelos; Kieu, Le H.; Eberl, Dennis D.; Blum, Alex E.; May, Jason T.
2011-01-01
Millions of pounds of mercury (Hg) were deposited in the river and stream channels of the Sierra Nevada from placer and hard-rock mining operations in the late 1800s and early 1900s. The resulting contaminated sediments are relatively harmless when buried and isolated from the overlying aquatic environment. The entrained Hg in the sediment constitutes a potential risk to human and ecosystem health should it be reintroduced to the actively cycling portion of the aquatic system, where it can become methylated and subsequently bioaccumulated in the food web. Each year, sediment is mobilized within these fluvial systems during high stormflows, transporting hundreds of tons of Hg-laden sediment downstream. The State of California and resource-management agencies, including the Bureau of Land Management (BLM) and the U.S. Forest Service, are concerned about additional disturbances, such as from suction gold dredging activities, which have the potential to mobilize Hg associated with buried sediment layers elevated in Hg that are otherwise likely to remain buried under normal storm conditions. The BLM initiated a study looking at the feasibility of removing Hg-contaminated sediment at the confluence of the South Yuba River and Humbug Creek in the northern Sierra Nevada of California by using standard suction-dredge technology. Additionally, the California State Water Resources Control Board (SWRCB) supported a comprehensive characterization of the intended dredge site. Together, the BLM and SWRCB supported a comprehensive characterization of Hg contamination at the site and the potential effects of sediment disturbance at locations with historical hydraulic mining debris on downstream environments. The comprehensive study consisted of two primary components: field studies and laboratory experiments. The field component, described in this report, had several study elements: 1) a preliminary, small-scale, in-stream dredge test; 2) comprehensive characterization of grain
Madricardo, Fantina; Foglini, Federica; Kruss, Aleksandra; Ferrarin, Christian; Pizzeghello, Nicola Marco; Murri, Chiara; Rossi, Monica; Bajo, Marco; Bellafiore, Debora; Campiani, Elisabetta; Fogarin, Stefano; Grande, Valentina; Janowski, Lukasz; Keppel, Erica; Leidi, Elisa; Lorenzetti, Giuliano; Maicu, Francesco; Maselli, Vittorio; Mercorella, Alessandra; Montereale Gavazzi, Giacomo; Minuzzo, Tiziano; Pellegrini, Claudio; Petrizzo, Antonio; Prampolini, Mariacristina; Remia, Alessandro; Rizzetto, Federica; Rovere, Marzia; Sarretta, Alessandro; Sigovini, Marco; Sinapi, Luigi; Umgiesser, Georg; Trincardi, Fabio
2017-09-01
Tidal channels are crucial for the functioning of wetlands, though their morphological properties, which are relevant for seafloor habitats and flow, have been understudied so far. Here, we release a dataset composed of Digital Terrain Models (DTMs) extracted from a total of 2,500 linear kilometres of high-resolution multibeam echosounder (MBES) data collected in 2013 covering the entire network of tidal channels and inlets of the Venice Lagoon, Italy. The dataset comprises also the backscatter (BS) data, which reflect the acoustic properties of the seafloor, and the tidal current fields simulated by means of a high-resolution three-dimensional unstructured hydrodynamic model. The DTMs and the current fields help define how morphological and benthic properties of tidal channels are affected by the action of currents. These data are of potential broad interest not only to geomorphologists, oceanographers and ecologists studying the morphology, hydrodynamics, sediment transport and benthic habitats of tidal environments, but also to coastal engineers and stakeholders for cost-effective monitoring and sustainable management of this peculiar shallow coastal system.
Selbig, William R.; Jopke, Peter L.; Marhshall, David W.; Sorge, Michael J.
2004-01-01
The U.S. Geological Survey (USGS), in cooperation with the Dane County Land Conservation Department (LCD) and the Wisconsin Department of Natural Resources (DNR), investigated the instream effects from construction of a residential subdivision on Brewery Creek in Dane County, Wisconsin. The purpose of the investigation was to determine whether a variety of storm-runoff and erosion-control best-management practices (BMPs) would effectively control the overall sediment load, as well as minimize any hydrologic, ecologic, and geomorphic stresses to Brewery Creek.
Energy Technology Data Exchange (ETDEWEB)
Reyes, J.; Goodarzi, F.; Sanei, H.; Stasiuk, L.D. [Environmental Study Group, Geological Survey of Canada-Calgary, 3303 33rd Street NW, Calgary, Alberta (Canada T2A 2A7); Duncan, W. [Teck Cominco Metals Ltd., Trail, British Columbia (Canada V1R 4L8)
2006-01-03
Fifty-six samples of stream sediments from 12 creeks in the vicinity of Trail, British Columbia, Canada were examined to determine their origin, characterize their organic matter and their relation to natural/geogenic and anthropogenic sources. The samples were initially screened by Rock-Eval(R) 6 pyrolysis for their TOC, HI, and OI contents and then examined by both reflected (polarized) and fluorescent light microscopy. It was found that organic matter in stream sediments is mostly from natural/biological sources from local vegetation, such as woody tissue, suberin, spores, and pollen, as well as altered natural/biological input from char formed due to forest fires. Anthropogenic organic matter, mostly coke particles, was also found in the stream sediments. The coke particles have anisotropic properties with medium grained texture formed from medium volatile bituminous coal. The occurrence of coke particles is limited to Ryan Creek located close to an area were some small gold, nickel, and lead smelting operations previously occurred. There is no evidence to indicate that the coke particles found in the creek are emitted from the lead and zinc smelter currently in operation in the area. There are no coal-bearing strata in the area that may have a direct input of coal fragments in any of the creeks. (author)
Stephen Sungnome Madrone; Andrew P. Stubblefield
2012-01-01
Erosion in the Mill and Luffenholtz Creek watersheds in Humboldt County, California, with their extensive clay soils, can lead to high turbidity levels in receiving bodies of water, increasing the costs of treating water for domestic water supplies. Detailed road and erosion surveys and monitoring of suspended sediment, discharge, and turbidity levels in Mill Creek (3....
Lima, A R A; Barletta, M; Costa, M F; Ramos, J A A; Dantas, D V; Melo, P A M C; Justino, A K S; Ferreira, G V B
2016-07-01
Lunar influence on the distribution of fish larvae, zooplankton and plastic debris in mangrove creeks of the Goiana Estuary, Brazil, was studied over a lunar cycle. Cetengraulis edentulus, Anchovia clupeoides and Rhinosardinia bahiensis were the most abundant fish larvae (56·6%), independent of the moon phase. The full moon had a positive influence on the abundance of Gobionellus oceanicus, Cynoscion acoupa and Atherinella brasiliensis, and the new moon on Ulaema lefroyi. The full and new moons also influenced the number of zoeae and megalopae of Ucides cordatus, protozoeae and larvae of caridean shrimps, and the number of hard and soft plastic debris, both 5 mm. Micro and macroplastics were present in samples from all 12 creeks studied, at densities similar to the third most abundant taxon, R. bahiensis. Cetengraulis edentulus and R. bahiensis showed a strong positive correlation with the last quarter moon, when there was less zooplankton available in the creeks and higher abundance of microplastic threads. Anchovia clupeoides, Diapterus rhombeus, U. lefroyi and hard microplastics were positively associated with different moon phases, when calanoid copepods, Caridean larvae and zoeae of U. cordatus were highly available in the creeks. Cynoscion acoupa, G. oceanicus and A. brasiliensis were strongly associated with the full moon, when protozoeae of caridean shrimps and megalopae of U. cordatus were also highly available, as were hard and soft macroplastics, paint chips (mangrove creeks as nursery habitats. The moon phases influenced the distribution of fish larvae species, zooplankton and plastic debris by changing their compositions and abundances in the mangrove creeks of the Goiana Estuary when under the influence of different tidal current regimes. © 2015 The Fisheries Society of the British Isles.
Jin, Hyun Mi; Jeong, Hye Im; Kim, Kyung Hyun; Hahn, Yoonsoo; Madsen, Eugene L; Jeon, Che Ok
2016-02-18
A genome-wide transcriptional analysis of Alteromonas naphthalenivorans SN2 was performed to investigate its ecophysiological behavior in contaminated tidal flats and seawater. The experimental design mimicked these habitats that either added naphthalene or pyruvate; tidal flat-naphthalene (TF-N), tidal flat-pyruvate (TF-P), seawater-naphthalene (SW-N), and seawater-pyruvate (SW-P). The transcriptional profiles clustered by habitat (TF-N/TF-P and SW-N/SW-P), rather than carbon source, suggesting that the former may exert a greater influence on genome-wide expression in strain SN2 than the latter. Metabolic mapping of cDNA reads from strain SN2 based on KEGG pathway showed that metabolic and regulatory genes associated with energy metabolism, translation, and cell motility were highly expressed in all four test conditions, probably highlighting the copiotrophic properties of strain SN2 as an opportunistic marine r-strategist. Differential gene expression analysis revealed that strain SN2 displayed specific cellular responses to environmental variables (tidal flat, seawater, naphthalene, and pyruvate) and exhibited certain ecological fitness traits -- its notable PAH degradation capability in seasonally cold tidal flat might be reflected in elevated expression of stress response and chaperone proteins, while fast growth in nitrogen-deficient and aerobic seawater probably correlated with high expression of glutamine synthetase, enzymes utilizing nitrite/nitrate, and those involved in the removal of reactive oxygen species.
Vegetation - Pine Creek WA and Fitzhugh Creek WA [ds484
California Natural Resource Agency — This fine-scale vegetation classification and map of the Pine Creek and Fitzhugh Creek Wildlife Areas, Modoc County, California was created following FGDC and...
International Nuclear Information System (INIS)
Churchill, R.C.; Meathrel, C.E.; Suter, P.J.
2004-01-01
The mining of gold can lead to toxic metals such as mercury (Hg) contaminating watercourses as by-products. The Reedy Creek sub-catchment, in northeast Victoria, Australia, was mined for gold in the 1850s. In 1998, samples were taken from six watercourses to measure any remaining toxic metal contamination in sediments and surface waters from two creeks with no previous gold mining (controls) and four that were mined. Although mean concentrations of Hg (measured using an ICP-OES) in sediments were below worldwide background levels, individual sites along Reedy Creek had slightly elevated Hg concentrations. In contrast, the Hg concentrations in the surface waters were above background levels. Temporal fluxes of very high Hg concentrations in the surface waters during periods of first flow and flood events revealed that Hg concentrations in the surface waters may, at certain times of the year, exceed all Australian and New Zealand Environment and Conservation Council (National Water Quality Management Strategy. Australian Water Quality Guidelines for Fresh and Marine Waters, ANZECC, 2000) guidelines for water use and the protection of the aquatic ecosystem
Persistence of effects of high sediment loading in a salmon-bearing river, northern California
Madej, Mary Ann; Ozaki, V.
2009-01-01
Regional high-magnitude rainstorms have produced several large floods in north coastal California during the last century, which resulted in extensive massmovement activity and channel aggradation. Channel monitoring in Redwood Creek, through the use of cross-sectional surveys, thalweg profi les, and pebble counts, has documented the persistence and routing of channel-stored sediment following these large floods in the 1960s and 1970s. Channel response varied on the basis of timing of peak aggradation. Channel-stored sediment was evacuated rapidly from the upstream third of the Redwood Creek channel, and the channel bed stabilized by 1985 as the bed coarsened. Currently only narrow remnants of flood deposits remain and are well vegetated. In the downstream reach, channel aggradation peaked in the 1990s, and the channel is still incising. Channel-bed elevations throughout the watershed showed an approximate exponential decrease with time, but decay rates were highest in areas with the thickest flood deposits. Pool frequencies and depths generally increased from 1977 to 1995, as did median residual water depths, but a 10 yr flood in 1997 resulted in a moderate reversal of this trend. Channel aggradation generated during 25 yr return interval floods has persisted in Redwood Creek for more than 30 yr and has impacted many life cycles of salmon. Watershed restoration work is currently focused on correcting erosion problems on hillslopes to reduce future sediment supply to Redwood Creek instead of attempting in-channel manipulations. ?? 2009 Geological Society of America.
Residual circulation and suspended sediment transport in the Dutch Wadden Sea
Duran-Matute, Matias; Sassi, Maximiliano; de Boer, Gerben; Grawë, Ulf; Gerkema, Theo; van Kessel, Thijs; Cronin, Katherine
2014-05-01
The Dutch Wadden Sea (DWS), situated between continental Europe and the Dutch Wadden Islands, is a semi enclosed basin connected to the North Sea by a series of tidal inlets and composed mainly of tidal flats and sea gullies. The DWS is of high ecological importance due to its biodiversity and has been declared a World Heritage site by UNESCO. It is a dynamic area subject to regional relative sea level rise due to global sea level rise, postglacial rebound and gas exploitation. For intertidal areas to continue to serve as feeding ground for migratory birds, a net import of sediment is required. Observations are crucial but provide only scarce information in space and time. Hence, to estimate the net influx of suspended sediment into the DWS, realistic high resolution three-dimensional numerical simulations have been carried out using the General Estuarine Transport Model (GETM). The hydrodynamics are mainly governed by the tides, the fresh water discharge from several sluices into the DWS and wind variability. It is expected that the transport of suspended particulate matter (SPM) is governed by the same factors, too, in combination with sediment sink and source terms. For validation, the results are compared against different observational data sets, such as tidal gauges, temperature and salinity at a fixed station, and the volumetric flux rate through one of the inlets obtained from an acoustic Doppler current profiler (ADCP) attached to a ferry. SPM transport is modeled for four different sediment classes each of which is defined by the critical shear stress and the settling velocity. Results show a clear net import of SPM through one of the inlets, which is in agreement with the observations. First estimates of the total sediment fluxes through the different inlets are presented together with an analysis on their variability and sensibility to the external forcing. Of particular importance is the net export of SPM during storms as well as the role of storms on
International Nuclear Information System (INIS)
Rikard, M.
1991-11-01
The Congaree Swamp National Monument is one of the last significant near virgin tracts of bottom land hardwood forests in the Southeast United States. The study documents a water quality monitoring program on Myers Creek, Reeves Creek and Toms Creek. Basic water quality parameters were analyzed. High levels of aluminum and iron were found, and recommendations were made for further monitoring
International Nuclear Information System (INIS)
Zhang, Rui; Guan, Minglei; Shu, Yujie; Shen, Liya; Chen, Xixi; Zhang, Fan; Li, Tiegang
2016-01-01
In order to investigate the historical records of lead contamination and source in coastal region of Haizhou Bay, Yellow Sea, a sediment core was collected from tidal flat, dated by 210 Pb and 137 Cs. Lead and its stable isotopic ratios were determined. The profiles of enrichment factor (EF) and Pb isotope ratios showed increasing trend upward throughout the core, correlating closely with the experience of a rapid economic and industrial development of the catchment. According to Pb isotopic ratios, coal combustion emission mainly contributed to the Pb burden in sediments. Based on end-member model, coal combustion emission dominated anthropogenic Pb sources in recent decades contributing from 48% to 67% in sediment. And the contribution of leaded gasoline was lower than 20%. A stable increase of coal combustion source was found in sediment core, while the contribution of leaded gasoline had declined recently, with the phase-out of leaded gasoline in China. - Highlights: •Pb contamination in tidal flat of Haizhou Bay was chronicled by a sediment core. •The coal combustion source dominated Pb contamination of Haizhou Bay. •Coal combustion source showed an increasing trend in four decades in Haizhou Bay.
Weathering of a petroleum spill in a tropical mangrove swamp
Energy Technology Data Exchange (ETDEWEB)
Fisher, S.J.; Alexander, R.; Kagi, R.I. [Curtin Univ., Perth (Australia)
1996-12-31
In August 1987, an indeterminate amount of petroleum condensate was released from a buried pipe leading to contamination of a tropical mangrove swamp surrounding a tidal creek in North Western Australia. Since no bioremediation was attempted at this site, we have monitored the natural weathering of the condensate by detailed analysis of the petroleum hydrocarbons extracted from sediment samples collected on 11 occasions over a 3 year period.
Monitoring Fine Sediment; Grande Ronde and John Day Rivers, 2000 Annual Report.
Energy Technology Data Exchange (ETDEWEB)
Rhodes, Jonathan J.; Greene, M. Jonas; Purser, Michael D. (Columbia River Inter-Tribal Fish Commission, Portland, OR)
2001-01-01
Fine sediment in spawning substrate has a major effect on salmon survival from egg to smolt. Basin-wide restoration plans have established targets for fine sediment levels in spawning habitat. The project was initiated to monitor surface fine sediment levels and overwinter intrusion of fine sediment in spring chinook salmon spawning habitat in the North Fork John Day (NFJDR) and Grande Ronde Rivers, for five years. The project is also investigating the potential relationship between surface fine levels and overwinter sedimentation. It will provide data to assess trends in substrate conditions in monitored reaches and whether trends are consistent with efforts to improve salmon habitat conditions. The data on the magnitude of overwinter sedimentation will also be used to estimate salmon survival from egg to emergence. In Sept. 1998, 1999, and Aug. 2000, sites for monitoring overwinter sedimentation were established in salmon spawning habitat in the upper Grande Ronde River, Catherine Creek (a Grande Ronde tributary), the North Fork John Day River (NFJDR), and Granite Creek (a NFJDR tributary). Surface fine sediment levels were measured in these reaches via the grid method and visually estimated to test the relative accuracy of these two methods. In 1999 and 2000, surface fine sediment was also estimated via pebble counts at selected reaches to allow comparison of results among the methods. Overwintering substrate samples were collected in April 1999 and April-May 2000 to estimate the amount of overwinter sedimentation in clean gravels in spawning habitat. Monitoring methods and locations are described.
Physical and Biological Regulation of Carbon Sequestration in Tidal Marshes
Morris, J. T.; Callaway, J.
2017-12-01
The rate of carbon sequestration in tidal marshes is regulated by complex feedbacks among biological and physical factors including the rate of sea-level rise (SLR), biomass production, tidal amplitude, and the concentration of suspended sediment. We used the Marsh Equilibrium Model (MEM) to explore the effects on C-sequestration across a wide range of permutations of these variables. C-sequestration increased with the rate of SLR to a maximum, then down to a vanishing point at higher SLR when marshes convert to mudflats. An acceleration in SLR will increase C-sequestration in marshes that can keep pace, but at high rates of SLR this is only possible with high biomass and suspended sediment concentrations. We found that there were no feasible solutions at SLR >13 mm/yr for permutations of variables that characterize the great majority of tidal marshes, i.e., the equilibrium elevation exists below the lower vertical limit for survival of marsh vegetation. The rate of SLR resulting in maximum C-sequestration varies with biomass production. C-sequestration rates at SLR=1 mm/yr averaged only 36 g C m-2 yr-1, but at the highest maximum biomass tested (5000 g/m2) the mean C-sequestration reached 399 g C m-2 yr-1 at SLR = 14 mm/yr. The empirical estimate of C-sequestration in a core dated 50-years overestimates the theoretical long-term rate by 34% for realistic values of decomposition rate and belowground production. The overestimate of the empirical method arises from the live and decaying biomass contained within the carbon inventory above the marker horizon, and overestimates were even greater for shorter surface cores.
Arsenic enrichment in mangroves, and sediments along Karachi coast, Pakistan
Directory of Open Access Journals (Sweden)
Rashida Parveen
2013-08-01
Full Text Available Objective: To assess the arsenic (As concentration in different parts of mangroves Avicennia marina and sediments in Karachi coastal area i.e. Korangi Creek , Manora, Kakapir and Sandspit. Methods: Sites are identified for sampling owing to their vicinity to industrial activities. Sandspit is targeted for its being devoid of industries. The hydride generation atomic absorption spectrometry (HG-AAS were used to analyse the concentration of arsenic in mangrove and sediment. Results: The high concentration of As was found in roots and middle aerial part as compared to the upper part of mangroves. The concentrations of As was found higher in sediments as compared to the mangroves. There is a seasonal variation of As enrichment in mangrove and sediments as dry seasons showed higher concentration while in rainy season dilution factors may be attributed to the low level of As. The concentration variation of As in sampling sites of mangroves and sediments following the trend i.e. Korangi Creek >Manora>Kakapir>Sandspit. The statistical analysis (Two way ANOVA of data exhibited no significant difference (P>0.05 for trace metals concentrations in mangrove as well as in sediments. Conclusions: It is obvious to conclude that As should be continuously monitored in different environmental segments. The data must correlate with geographical distribution of As, quantification in different species, their solubility and bioavailability to understand the possible factors responsible for environmental pollution. The present study will be helpful to improve water management resources.
Artificial Crab Burrows Facilitate Desalting of Rooted Mangrove Sediment in a Microcosm Study
Directory of Open Access Journals (Sweden)
Nathalie Pülmanns
2015-07-01
Full Text Available Water uptake by mangrove trees can result in salt accumulation in sediment around roots, negatively influencing growth. Tidal pumping facilitates salt release and can be enhanced by crab burrows. Similarly, flushing of burrows by incoming tidal water decreases sediment salinity. In contrast to burrows with multiple entrances, the role of burrows with one opening for salinity reduction is largely unknown. In a microcosm experiment we studied the effect of artificial, burrow-like macro-pores with one opening on the desalting of mangrove sediment and growth of Rhizophora mangle L. seedlings. Sediment salinity, seedling leaf area and seedling growth were monitored over six months. Artificial burrows facilitated salt release from the sediment after six weeks, but seedling growth was not influenced. To test whether crab burrows with one opening facilitate salt release in mangrove forests, sediment salinities were measured in areas with and without R. mangle stilt roots in North Brazil at the beginning and end of the wet season. In addition, burrows of Ucides cordatus were counted. High crab burrow densities and sediment salinities were associated with stilt root occurrence. Precipitation and salt accumulation by tree roots seem to have a larger effect on sediment salinity than desalting by U. cordatus burrows.
Residual flow patterns and morphological changes along a macro- and meso-tidal coastline
Leonardi, Nicoletta; Plater, Andrew James
2017-11-01
The hydrodynamic and residual transport patterns arising from oscillating tidal motion have important consequences for the transport of sediments, and for the evolution of the shoreline, especially under macro- and meso-tidal conditions. For many locations there are significant uncertainties about residual currents and sediment transport characteristics, and their possible influence on the morphological evolution of the coastline and on the character of the bed. Herein we use the coastline of SE England as a test case to investigate possible changes in residual currents, and residual transport patterns from neap to spring tide, the reciprocal interaction between residuals and the character of the bed, and the morphological evolution of the coastline at a century timescale. We found that in the long term the morphology of the system evolves toward a dynamic equilibrium configuration characterized by smaller, and spatially constant residual transport patterns. While the spatial distribution of residual currents maintains a similar trend during both neap and spring tide, during spring tide and for large areas residual currents switch between northerly and southerly directions, and their magnitude is doubled. Residual eddies develop in regions characterized by the presence of sand bars due to the interaction of the tide with the varying topography. Residual transport patterns are also computed for various sediment fractions, and based on the hydrodynamics and sediment availability at the bottom. We found that the distribution of sediments on the bed is significantly correlated with the intensity of residuals. Finally, the majority of long-term morphological changes tend to develop or augment sand banks features, with an increase in elevation and steepening of the bank contours.
Binding behaviour of uranium in sediment samples across Thane Creek Area
International Nuclear Information System (INIS)
Maity, Sukanta; Sandeep, P.; Dusane, C.B.; Sahu, S.K.; Pandit, G.G.
2018-01-01
Natural and artificial radionuclides have received much attention in the past decades for the protection and management of the marine environment and for better understanding of oceanographic and sedimentological processes. Pathways that could supply significant amounts of natural radionuclides in the marine environment are: river runoff (effluents discharges to river and from coastal locations), direct groundwater discharge and wind-blown particles. The shore and bottom sediments accumulate radionuclides by sorption from seawater or by sedimentation of suspended radioactive solids. The radionuclides that remain associated with sediments are influenced greatly by the chemical, biochemical and microbiological changes that take place in the environment. In general, radionuclide properties in environmental media depend on the form in which each species is bound with the reactivity of that species, rather than on the total concentrations, so there is considerable interest in understanding uranium binding behavior in sediments in different conditions
Langner, H.; Young, M.; Staats, M. F.
2013-12-01
Methylmercury contamination in biota is a major factor diminishing the environmental quality of the Upper Clark Fork River (CFR), e.g. by triggering human consumption limits of fish. The CFR is subject to one of the largest Superfund cleanup projects in the US, but remediation and restoration is currently focused exclusively on other mining-related contaminants (As, Cu, Zn, Pb, Cd), which may be counterproductive with respect to the bio-availability of mercury, for example by creation of wetlands along mercury-contaminated reaches of the river. The identification and elimination of Hg sources is an essential step toward reducing the methylmercury exposure in the biota of the CFR watershed because a strong correlation exists between total mercury levels in river sediment and methylmercury levels in aquatic life. We analyzed duplicate samples from the top sediment layer of the main stem and significant tributaries to the Clark Fork River along a 240 km reach between Butte, MT and downstream of the Missoula Valley. Mercury concentrations were 1.3 × 1.6 (mean × SD, n = 35) in the main stem. Concentrations in tributaries varied widely (0.02 to 85 mg/kg) and seemed only loosely related to the number of historic precious metal mines in the watershed. In the upper reach of the CFR, elevated Hg levels are likely caused by residual contaminated sediments in the flood plain. Levels tend to decrease downstream until Drummond, MT, where Flint Creek contributes a significant amount of mercury, causing Hg levels in the main stem CFR to increase from 0.7 to 4 mg/kg. Levels continue to decrease downstream. Flint Creek is the single largest contributor of Hg to the CFR. Detailed sampling of the main stem Flint Creek and tributaries (26 sites) showed extremely high levels in two tributaries (22 to 85 mg/kg) where historic milling operations were located. Elimination of these point sources may be accomplished comparatively economically and may significantly reduce mercury levels in
[AVS concentrations in Xinan Creek and the influencing factors].
Liu, Xiao-Bing; Wen, Yan-Mao; Li, Feng; Wu, Chang-Hua; Duan, Zhi-Peng
2012-07-01
Sediment and overlying water samples were collected at 10 sampling stations at Xinan Creek, a tidal river in Pearl River Delta, and analyzed for physical and chemical characteristics as well as microbial incicators, in order to reveal the main factors dominating the spatial distribution of acid volatile sulfide (AVS). The effects of Eh, SRB OC and TS on the spatial distribution of AVS were investigated and the impact of AVS on the toxicity of heavy metals in the studied area was evaluated. The results showed that the range of AVS was 0.207-41.453 micromol x g(-1), with an average of 6.684 micromol x g(-1), which is relatively high compared to the results in other studies. The AVS value of the surface layer was higher than the bottom layer in 5 stations. The AVS values in both the surface layer and the bottom layer were highly variable, the coefficients of variation being 93.61% and 153.09% , respectively. The analytical results revealed that TS was the factor with the greatest impact on the spatial distribution of AVS, and the order was TS > OC > Eh > SRB. Potential ecological risk of heavy metals existed in 60% of the smpling stations based on the value of Sigma (SEM5-AVS), however, with the criterion of [Sigma(SEM5-AVS)]/foc, none of them had inacceptable ecological risk. Furthermore, in terms of single species of heavy metals, there was certain risk of toxic effect for all the five heavy metals (Cd, Ni, Cu, Zn and Pb). The above mentioned results will provide valuable data for the in-depth study of the formation mechanism of AVS and helpful reference for environmental impact assessment and scientific rehabilitation of heavy metals in polluted rivers.
Van Maren, D.S.; Gerritsen, H.
2012-01-01
The Singapore Strait connects the South China Sea, where tides are dominantly diurnal, to the dominantly semidiurnal Indian Ocean. At this transition, the tidal water level oscillations are observed to be semidiurnal while the tidal current oscillations are mixed, diurnal to fully diurnal. Due to
Suspended sediment load in the tidal zone of an Indonesian River
Buschman, F.A.; Hoitink, A.J.F.; Jong, S.M. de; Hoekstra, P.; Hidayat, H.; Sassi, M. G.
2012-01-01
Forest clearing for reasons of timber production, open pit mining and the establishment of oil palm plantations generally results in excessively high sediment loads in tropical rivers. The increasing sediment loads pose a threat to coastal marine ecosystems, such as coral reefs. This
International Nuclear Information System (INIS)
Mashhoon, B.
1977-01-01
The general theory of tides is developed within the framework of Einstein's theory of gravitation. It is based on the concept of Fermi frame and the associated notion of tidal frame along an open curve in spacetime. Following the previous work of the author an approximate scheme for the evaluation of tidal gravitational radiation is presented which is valid for weak gravitational fields. The emission of gravitational radiation from a body in the field of a black hole is discussed, and for some cases of astrophysical interest estimates are given for the contributions of radiation due to center-of-mass motion, purely tidal deformation, and the interference between the center of mass and tidal motions
Suspended sediment load in the tidal zone of an Indonesian river
Buschman, F. A.; Hoitink, A. J. F.; de Jong, S. M.; Hoekstra, P.; Hidayat, H.; Sassi, M. G.
2012-01-01
Forest clearing for reasons of timber production, open pit mining and the establishment of oil palm plantations generally results in excessively high sediment loads in tropical rivers. The increasing sediment loads pose a threat to coastal marine ecosystems, such as coral reefs. This study presents
White Oak Creek Embayment site characterization and contaminant screening analysis
International Nuclear Information System (INIS)
Blaylock, B.G.; Ford, C.J.; Frank, M.L.; Hoffman, F.O.; Hook, L.A.
1993-01-01
Analyses of sediment samples collected near the mouth of White Oak Creek during the summer of 1990 revealed 137 Cs concentrations [> 10 6 Bq/kg dry wt (> 10 4 pCi/g dry wt)] near the sediment surface. Available evidence indicates that these relatively high concentrations of 137 Cs now at the sediment surface were released from White Oak Dam in the mid-1950s and had accumulated at depositionalsites in the embayment. These accumulated sediments are being eroded and transported downstream primarily during winter low-water levels by flood events and by a combination of normal downstream flow and the water turbulence created by the release of water from Melton Hill Dam during hydropower generation cycles. This report provides a more thorough characterization of the extent of contamination in WOCE than was previously available. Environmental samples collected from WOCE were analyzed for organic, inorganic, and radiological contaminants in fish, water, and sediment. These results were used to conduct a human health effects screening analysis. Walkover radiation surveys conducted inside the fenced area surrounding the WOCE at summer-pool (741 ft MSL) and at winter-pool (733 ft MSL) level, indicated a maximum exposure rate of 3 mR h 1 1 m above the soil surface
Shiratori, Takashi; Ishida, Ken-Ichiro
2016-05-01
The genus Entamoeba includes anaerobic lobose amoebae, most of which are parasites of various vertebrates and invertebrates. We report a new Entamoeba species, E. marina n. sp. that was isolated from a sample of tidal flat sediment collected at Iriomote Island, Okinawa, Japan. Trophozoites of E. marina were 12.8-32.1 μm in length and 6.8-15.9 μm in width, whereas the cysts were 8.9-15.8 μm in diam. and contained four nuclei. The E. marina cells contained a rounded nucleus with a small centric karyosome and uniformly arranged peripheral chromatin. Although E. marina is morphologically indistinguishable from other tetranucleated cyst-forming Entamoeba species, E. marina can be distinguished from them based on the combination of molecular phylogenetic analyses using SSU rDNA gene and the difference of collection sites. Therefore, we propose E. marina as a new species of the genus Entamoeba. © 2015 The Author(s) Journal of Eukaryotic Microbiology © 2015 International Society of Protistologists.
Morphology and Sediment Dynamics of the East Friesian Tidal Inlets, West Germany.
1982-01-01
by three major environmental factors: (1) the tide range, (2) the nearshore wave energy, and (3) the geometry of the hack -barrier hav. Both...ASg .147 Ebb a A~ ps4 . 0.1 Fig. 15(a) and (b). For legend see opposite. 18 t7 7d 7’AI 3LI EBBTIALDELA ARI- HNE Juy1 .17 EBBW TIDAL DELTA MARINCHNL j
Roos, A.
1997-01-01
Basic phenomena, origin and generation of tides, analysis and prediction of tides, basic equation and types of long waves in one dimension, tidal propagation in one dimension, tidal propagation in two directions, analytical tidal computation, numerical tidal computation.
Bachmann, S.; De La Fuente, J. A.; Hill, B.; Mai, C.; Mikulovsky, R. P.; Mondry, Z.; Rust, B.; Young, D.
2013-12-01
The US Forest Service is conducting a study of sediment mobilization, transport, and deposition on the Bagley Fire, which burned about 18,000 hectares in late summer, 2012, on the Shasta-Trinity National Forest, south of McCloud, CA. The fire area is in steep terrain of the Eastern Klamath Mountains that are underlain primarily by metasedimentary rock. The watersheds affected drain into the headwaters of Squaw Creek, along with small streams tributary to the McCloud and Pit Rivers, all of which flow into Shasta Lake Reservoir. In November and December of 2012, intense storms occurred over the fire area with estimated return intervals of 25-50 years, based on 4-day storm totals in ranging from 38 to 56 cm. The Squaw Creek storm response was unique for this area, in that it remained turbid for about 2 months following the storms. Subsequent small storms through June, 2013 have also generated prolonged turbidity. This may be attributable to the remobilization of fine particles temporarily stored in the channel network. Preliminary observations from field reconnaissance include the following: a) Erosional processes were dominated by sheet, rill, and gully erosion, and the resulting sediment delivered to channels was rich in fine particles and gravels; b) Landslides were infrequent, and as a result, a limited amount of large rock and logs were delivered to channels; c) Sediment laden flows occurred in most burned low order channels, but classic debris flows, those scouring all vegetation from channel bottoms, were very uncommon; d) Most road stream crossing culverts failed in high severity burn areas; e) Low gradient stream reaches in Squaw Creek were aggraded with fine sediment; f) Sustained high levels of turbidity occurred in the main stem of Squaw Creek. The goals of this study are to characterize relative roles of surface erosion, landslides, and debris flows in delivering sediment to streams after the fire, and if possible, to develop a rough sediment budget
Directory of Open Access Journals (Sweden)
Catherine E. Lovelock
2017-05-01
Full Text Available The sediments of coastal wetlands contain large stores of carbon which are vulnerable to oxidation once disturbed, resulting in high levels of CO2 emissions that may be avoided if coastal ecosystems are conserved or restored. We used a simple model to estimate CO2 emissions from mangrove forests, seagrass beds, and tidal marshes based on known decomposition rates for organic matter in these ecosystems under either oxic or anoxic conditions combined with assumptions of the proportion of sediment carbon being deposited in either oxic or anoxic environments following a disturbance of the habitat. Our model found that over 40 years after disturbance the cumulative CO2 emitted from tidal marshes, mangrove forests, and seagrass beds were ~70–80% of the initial carbon stocks in the top meter of the sediment. Comparison of our estimates of CO2 emissions with empirical studies suggests that (1 assuming 50% of organic material moves to an oxic environment after disturbance gives rise to estimates that are similar to CO2 emissions reported for tidal marshes; (2 field measurements of CO2 emissions in disturbed mangrove forests were generally higher than our modeled emissions that assumed 50% of organic matter was deposited in oxic conditions, suggesting higher proportions of organic matter may be exposed to oxic conditions after disturbance in mangrove ecosystems; and (3 the generally low observed rates of CO2 emissions from disturbed seagrasses compared to our estimates, assuming removal of 50% of the organic matter to oxic environments, suggests that lower proportions may be exposed to oxic conditions in seagrass ecosystems. There are significant gaps in our knowledge of the fate of wetland sediment carbon in the marine environment after disturbance. Greater knowledge of the distribution, form, decomposition, and emission rates of wetland sediment carbon after disturbance would help to improve models.
Nonpoint sources of runoff from agricultural lands are believed to be responsible for elevated nutrient and sediment levels in the Black Creek Watershed (BCW). This watershed located in Shelby County in Northeast Missouri covers an area of 140 km2. The purpose of this project was to quantify sedimen...
Super(210) Pb based trace element fluxes in the nearshore and estuarine sediments off Bombay, India
Digital Repository Service at National Institute of Oceanography (India)
Sharma, P.; Borole, D.V.; Zingde, M.D.
Seven sediment cores from the Thana Creek-Bombay harbour complex (THC) have been studied for excess super(210) Pb (super(210) Pb sub(exc), that portion of super(210) Pb not supported by decay of super(226) Ra in sediment), C sub(org), Mn, Fe, Co, Ni...
Mercury and methylmercury concentrations and loads in the Cache Creek watershed, California
Energy Technology Data Exchange (ETDEWEB)
Domagalski, Joseph L.; Alpers, Charles N.; Slotton, Darell G.; Suchanek, Thomas H.; Ayers, Shaun M
2004-07-05
Concentrations and loads of total mercury and methylmercury were measured in streams draining abandoned mercury mines and in the proximity of geothermal discharge in the Cache Creek watershed of California during a 17-month period from January 2000 through May 2001. Rainfall and runoff were lower than long-term averages during the study period. The greatest loading of mercury and methylmercury from upstream sources to downstream receiving waters, such as San Francisco Bay, generally occurred during or after winter rainfall events. During the study period, loads of mercury and methylmercury from geothermal sources tended to be greater than those from abandoned mining areas, a pattern attributable to the lack of large precipitation events capable of mobilizing significant amounts of either mercury-laden sediment or dissolved mercury and methylmercury from mine waste. Streambed sediments of Cache Creek are a significant source of mercury and methylmercury to downstream receiving bodies of water. Much of the mercury in these sediments is the result of deposition over the last 100-150 years by either storm-water runoff, from abandoned mines, or continuous discharges from geothermal areas. Several geochemical constituents were useful as natural tracers for mining and geothermal areas, including the aqueous concentrations of boron, chloride, lithium and sulfate, and the stable isotopes of hydrogen and oxygen in water. Stable isotopes of water in areas draining geothermal discharges showed a distinct trend toward enrichment of {sup 18}O compared with meteoric waters, whereas much of the runoff from abandoned mines indicated a stable isotopic pattern more consistent with local meteoric water.
Mercury and methylmercury concentrations and loads in the Cache Creek watershed, California
International Nuclear Information System (INIS)
Domagalski, Joseph L.; Alpers, Charles N.; Slotton, Darell G.; Suchanek, Thomas H.; Ayers, Shaun M.
2004-01-01
Concentrations and loads of total mercury and methylmercury were measured in streams draining abandoned mercury mines and in the proximity of geothermal discharge in the Cache Creek watershed of California during a 17-month period from January 2000 through May 2001. Rainfall and runoff were lower than long-term averages during the study period. The greatest loading of mercury and methylmercury from upstream sources to downstream receiving waters, such as San Francisco Bay, generally occurred during or after winter rainfall events. During the study period, loads of mercury and methylmercury from geothermal sources tended to be greater than those from abandoned mining areas, a pattern attributable to the lack of large precipitation events capable of mobilizing significant amounts of either mercury-laden sediment or dissolved mercury and methylmercury from mine waste. Streambed sediments of Cache Creek are a significant source of mercury and methylmercury to downstream receiving bodies of water. Much of the mercury in these sediments is the result of deposition over the last 100-150 years by either storm-water runoff, from abandoned mines, or continuous discharges from geothermal areas. Several geochemical constituents were useful as natural tracers for mining and geothermal areas, including the aqueous concentrations of boron, chloride, lithium and sulfate, and the stable isotopes of hydrogen and oxygen in water. Stable isotopes of water in areas draining geothermal discharges showed a distinct trend toward enrichment of 18 O compared with meteoric waters, whereas much of the runoff from abandoned mines indicated a stable isotopic pattern more consistent with local meteoric water
Harris, David Dell; Williams, Robert Charles
1971-01-01
Data collected during the prelogging period 1959-65 indicate an average annual runoff for Needle Branch and Deer and Flynn Creeks of 74.2, 75.1, and 77.7 inches, respectively. The measured precipitation at Flynn Creek of 92.9 inches was 5 inches less than at either Needle Branch or Deer Creek. Unit flood runoff during the prelogging period was found to be lowest on Flynn Creek and highest on Needle Branch. On Needle Branch, there appear to be two distinct low-flow patterns, one for a saturated and one for an unsaturated soil condition. The average annual sediment yield was highest on Flynn Creek, 321 tons per square mile, and lowest on Needle Branch, 166 tons per square mile. Maximum water temperatures were 62?F on Flynn Creek and 61?F on Needle Branch and Deer Creek.
Simulation of suspended sediment transport initialized with satellite ...
Indian Academy of Sciences (India)
Sediment dynamics like deposition, erosion and dispersion are explained with the simu- lated tidal currents and .... P and q=the flux in the x and y directions, respec- tively, h=water ..... Babu K S, Dwarakish G S and Jayakumar S 2003 Model-.
Schoellhamer, D.H.; Ganju, N.K.; Mineart, P.R.; Lionberger, M.A.; Kusuda, T.; Yamanishi, H.; Spearman, J.; Gailani, J. Z.
2008-01-01
Bathymetric change in tidal environments is modulated by watershed sediment yield, hydrodynamic processes, benthic composition, and anthropogenic activities. These multiple forcings combine to complicate simple prediction of bathymetric change; therefore, numerical models are necessary to simulate sediment transport. Errors arise from these simulations, due to inaccurate initial conditions and model parameters. We investigated the response of bathymetric change to initial conditions and model parameters with a simplified zero-dimensional cohesive sediment transport model, a two-dimensional hydrodynamic/sediment transport model, and a tidally averaged box model. The zero-dimensional model consists of a well-mixed control volume subjected to a semidiurnal tide, with a cohesive sediment bed. Typical cohesive sediment parameters were utilized for both the bed and suspended sediment. The model was run until equilibrium in terms of bathymetric change was reached, where equilibrium is defined as less than the rate of sea level rise in San Francisco Bay (2.17 mm/year). Using this state as the initial condition, model parameters were perturbed 10% to favor deposition, and the model was resumed. Perturbed parameters included, but were not limited to, maximum tidal current, erosion rate constant, and critical shear stress for erosion. Bathymetric change was most sensitive to maximum tidal current, with a 10% perturbation resulting in an additional 1.4 m of deposition over 10 years. Re-establishing equilibrium in this model required 14 years. The next most sensitive parameter was the critical shear stress for erosion; when increased 10%, an additional 0.56 m of sediment was deposited and 13 years were required to re-establish equilibrium. The two-dimensional hydrodynamic/sediment transport model was calibrated to suspended-sediment concentration, and despite robust solution of hydrodynamic conditions it was unable to accurately hindcast bathymetric change. The tidally averaged
Deformation of textural characteristics and sedimentology along micro-tidal estuarine beaches
Digital Repository Service at National Institute of Oceanography (India)
Dora, G.U.; SanilKumar, V.; Philip, C.S.; Johnson, G.
Indian Journal of Geo Marine Sciences Vol. 45 (11), November 2016, pp. 1432-1444 *Corresponding author Deformation of textural characteristics and sedimentology along micro- tidal estuarine beaches G. Udhaba Dora, V. Sanil Kumar*, C... sediment is a foremost parameter for a coastal researcher/engineer/designer due to its various applications for sorting out a coastal environment. Sedimentary process at foreshore zone is a highly dynamical whereas textural characteristics...
Habitat and hydrology: assessing biological resources of the Suwannee River Estuarine System
Raabe, Ellen A.; Edwards, Randy E.; McIvor, Carole C.; Grubbs, Jack W.; Dennis, George D.
2007-01-01
The U.S. Geological Survey conducted a pilot integrated-science study during 2002 and 2003 to map, describe, and evaluate benthic and emergent habitats in the Suwannee River Estuary on the Gulf Coast of Florida. Categories of aquatic, emergent, and terrestrial habitats were determined from hyperspectral imagery and integrated with hydrologic data to identify estuarine fish habitats. Maps of intertidal and benthic habitat were derived from 12-band, 4-m resolution hyperspectral imagery acquired in September 2002. Hydrologic data were collected from tidal creeks during the winter of 2002-03 and the summer-fall of 2003. Fish were sampled from tidal creeks during March 2003 using rivulet nets, throw traps, and seine nets. Habitat characteristics, hydrologic data, and fish assemblages were compared for tidal creeks north and south of the Suwannee River. Tidal creeks north of the river had more shoreline edge and shallow habitat than creeks to the south. Tidal creeks south of the river were generally of lower salinity (fresher) and supported more freshwater marsh and submerged aquatic vegetation. The southern creeks tended to be deeper but less sinuous than the northern creeks. Water quality and inundation were evaluated with hydrologic monitoring in the creeks. In-situ gauges, recording pressure and temperature, documented a net discharge of brackish to saline groundwater into the tidal creeks with pronounced flow during low tide. Groundwater flow into the creeks was most prominent north of the river. Combined fish-sampling results showed an overall greater abundance of organisms and greater species richness in the southern creeks, nominally attributed a greater range in water quality. Fish samples were dominated by juvenile spot, grass shrimp, bay anchovy, and silverside. The short time frame for hydrologic monitoring and the one-time fish-sampling effort were insufficient for forming definitive conclusions. However, the combination of hyperspectral imagery and
Miller, David; Haddon, Elizabeth; Langenheim, Victoria; Cyr, Andrew J.; Wan, Elmira; Walkup, Laura; Starratt, Scott W.
2018-01-01
Hinkley Valley in the Mojave Desert, near Barstow about 140 km northeast of Los Angeles and midway between Victorville Valley and the Lake Manix basin, contains a thick sedimentary sequence delivered by the Mojave River. Our study of sediment cores drilled in the valley indicates that Hinkley Valley was probably a closed playa basin with stream inflow from four directions prior to Mojave River inflow. The Mojave River deposited thick and laterally extensive clastic wedges originating from the southern valley that rapidly filled much of Hinkley Valley. Sedimentary facies representing braided stream, wetland, delta, and lacustrine depositional environments all are found in the basin fill; in some places, the sequence is greater than 74 m (245 ft) thick. The sediment is dated in part by the presence of the ~631 ka Lava Creek B ash bed low in the section, and thus represents sediment deposition after Victorville basin was overtopped by sediment and before the Manix basin began to be filled. Evidently, upstream Victorville basin filled with sediment by about 650 ka, causing the ancestral Mojave River to spill to the Harper and Hinkley basins, and later to Manix basin.Initial river sediment overran wetland deposits in many places in southern Hinkley Valley, indicating a rapidly encroaching river system. These sediments were succeeded by a widespread lake (“blue” clay) that includes the Lava Creek B ash bed. Above the lake sediment lies a thick section of interlayered stream sediment, delta and nearshore lake sediment, mudflat and/or playa sediment, and minor lake sediment. This stratigraphic architecture is found throughout the valley, and positions of lake sediment layers indicate a successive northward progression in the closed basin. A thin overlapping sequence at the north end of the valley contains evidence for a younger late Pleistocene lake episode. This late lake episode, and bracketing braided stream deposits of the Mojave River, indicate that the river
Radionuclides and trace elements in middle Chesapeake Bay sediments
International Nuclear Information System (INIS)
Gavrilas, M.
1988-01-01
Sediments play an important role in aquatic ecology by serving as a repository for radioactive substances and for soluble chemical pollutants that they may transport over considerable distances and may pass to a higher trophic level by way of bottom-feeding biota. The Chesapeake Bay is a moderately stratified, drowned river valley estuary. The oscillatory flood and ebb of the tidal currents are the most obvious motions in the bay and its tributary estuaries. It is considered that the distribution of most of the pollutants, once diluted by the mixing action of the tidal flow, remains relatively constant for many miles up and down the bay. This paper documents the present status of the radioactivity and of trace elements in sediment samples collected in March 1986 from and extended area around the Calvert Cliffs Nuclear Power Plant
Digital Repository Service at National Institute of Oceanography (India)
Revichandran, C.; Balachandran, K.K.; Xavier, J.K.; Rejendran, N.C.
Spatial and seasonal variation of different physical processes governing the transport of salt and sediment of the Muvattupuzha River, in Kerala, India are discussed. Salt and suspended sediment due to tidal pumping was directed upstream, salt...
Xiong, Jilian; Wang, Xiao Hua; Wang, Ya Ping; Chen, Jingdong; Shi, Benwei; Gao, Jianhua; Yang, Yang; Yu, Qian; Li, Mingliang; Yang, Lei; Gong, Xulong
2018-06-01
An understanding of the dynamics and behaviors of suspended sediments is vital in analysis of morphological, environmental, and ecological processes occurring in coastal marine environments. To study the mechanisms of maintaining high suspended sediment concentrations (SSCs) on a tide-dominated offshore shoal, we measured water depths, current velocities, SSCs, wave parameters and bottom sediment compositions in the southern Yellow Sea. These data were then used to calculate bottom shear stresses generated by currents (τc), waves (τw), and wave-current interactions (τcw). SSCs time series exhibited strong quarter-diurnal peaks during spring tides, in contrast to the semidiurnal signal during neap tides. A Fourier analysis showed that suspended sediment variations within tidal cycles was mainly controlled by resuspension in most stations. There existed relatively stable background SSCs (maintaining high SSCs among tidal cycles) values at all four stations during both windy (wind speed > 9.0 m/s) and normal weather conditions (wind speed value of 0.21 N/m2. On account of the strong tidal currents, background SSCs of spring tides were greater than that of neap tides. In addition, on the base of wavelet, statistics analyses and turbulence dissipation parameter, background SSCs during slack tide in the study area may be maintained by intermittent turbulence events induced by a combined tidal current and wave action.
Transport of bedload sediment and channel morphology of a southeast Alaska stream.
Margaret A. Estep; Robert L. Beschta
1985-01-01
During 1980-81, transport of bedload sediment and channel morphology were determined at Trap Bay Creek, a third-order stream that drains a 13.5-square kilometer watershed on Chichagof island in southeast Alaska. Bedload sediment was sampled for 10 storms: peak flows ranged from 0.6 to 19.0 cubic meters per second, and transport rates ranged from 4 to 4400 kilograms per...
International Nuclear Information System (INIS)
1991-01-01
Volume 2 of this IM/IRA Plan contains OU 2 surface water, sediment, ground water and soil chemistry data, as well as the South Walnut Creek Basin Surface Water IM/IRA schedule and a tabulation of ARARs. (FL)
Origin of discontinuities in coal-bearing strata at Roaring Creek (Basal Pennsylvanian of Indiana)
Energy Technology Data Exchange (ETDEWEB)
Nelson, W J; Eggert, D L; Dimichele, W A; Stecyk, A C
1985-05-01
Basal Pennsylvanian coal-bearing strata exposed along Roaring Creek, west-central Indiana, exhibit extreme lateral discontinuity. Coal seams abruptly change in thickness and elevation; they split, grade into shale, are cut out by channels and disrupted by soft-sediment deformational structures. Initial sediments were laid down by a network of southwest- flowing streams that traversed a deeply channelized upland surface of Mississippian carbonate rocks. Channels aggraded rapidly as uplands were worn down, so the region changed through time from uplands to upper deltaic plain. Local environments included channels, localized point bars, small natural levees and crevasse splays, overbank deposits, and swamps. Differential compaction and subsidence, slumping stream banks, and possibly collapsing sinkholes influenced sedimentation. As a consequence, coals are too discontinuous for economical mining, although they are locally thick and high in quality. 16 references.
Flood-inundation maps for Indian Creek and Tomahawk Creek, Johnson County, Kansas, 2014
Peters, Arin J.; Studley, Seth E.
2016-01-25
Digital flood-inundation maps for a 6.4-mile upper reach of Indian Creek from College Boulevard to the confluence with Tomahawk Creek, a 3.9-mile reach of Tomahawk Creek from 127th Street to the confluence with Indian Creek, and a 1.9-mile lower reach of Indian Creek from the confluence with Tomahawk Creek to just beyond the Kansas/Missouri border at State Line Road in Johnson County, Kansas, were created by the U.S. Geological Survey in cooperation with the city of Overland Park, Kansas. The flood-inundation maps, which can be accessed through the U.S. Geological Survey Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the U.S. Geological Survey streamgages on Indian Creek at Overland Park, Kansas; Indian Creek at State Line Road, Leawood, Kansas; and Tomahawk Creek near Overland Park, Kansas. Near real time stages at these streamgages may be obtained on the Web from the U.S. Geological Survey National Water Information System at http://waterdata.usgs.gov/nwis or the National Weather Service Advanced Hydrologic Prediction Service at http://water.weather.gov/ahps/, which also forecasts flood hydrographs at these sites.Flood profiles were computed for the stream reaches by means of a one-dimensional step-backwater model. The model was calibrated for each reach by using the most current stage-discharge relations at the streamgages. The hydraulic models were then used to determine 15 water-surface profiles for Indian Creek at Overland Park, Kansas; 17 water-surface profiles for Indian Creek at State Line Road, Leawood, Kansas; and 14 water-surface profiles for Tomahawk Creek near Overland Park, Kansas, for flood stages at 1-foot intervals referenced to the streamgage datum and ranging from bankfull to the next interval above the 0.2-percent annual exceedance probability flood level (500-year recurrence interval). The
Seismic modelling of coal bed methane strata, Willow Creek, Alberta
Energy Technology Data Exchange (ETDEWEB)
Richardson, S.E.; Mayer, R.; Lawton, D.C.; Langenberg, W. [Consortium for Research in Elastic Wave Exploration Seismology, Calgary, AB (Canada)
2001-07-01
The purpose is to determine the feasibility of applying high- resolution reflection seismic surveying to coalbed methane (CBM) exploration and development. Numerical reflection seismic methods are examined for measuring the mapping continuity and coherence of coal zones. Numerical modelling of a coal zone in Upper Cretaceous sediments near Willow Creek, Alberta indicates that seismic data that is predominantly of 100 Hz is required to map the coal zone and lateral facies variations within the deposit. For resolution of individual coal seams, a central frequency >150 Hz would be needed. 26 refs., 17 figs., 3 tabs.
Directory of Open Access Journals (Sweden)
Ulung Jantama Wisha
2016-03-01
Full Text Available ANALYSIS OF TIDAL RANGE AND ITS EFFECT ON DISTRIBUTION OF TOTAL SUSPENDED SOLID (TSS IN THE PARE BAY WATERSPare Bay conditions is closely related to the mechanism of circulation in Makasar Strait. One of the problems that occur in Pare Bay waters is increased turbidity and low dynamics of transport inside the bay, which caused silting in some parts of the bay. The aim of this study was to determine tidal range characteristics and the influence of suspended sediment distribution as analysis of the sedimentation process and siltation at Pare bay. Descriptive quantitative method was used and the survey location was based on purposive sampling method. Tidal type in Pare Bay water was mix mainly semidiurnal tides with Formzahl Value was 0.895. The value of the water level below the lowest tide (Z0 was 1036.44 cm. Mean sea level (MSL value was 1107.97 cm. The vertical datum of MHHWS and MLLWS were 1143.47 cm and 1072.47 cm. Tidal range cycle in spring condition was 102-129,56 cm bigger than cycle in neap condition ranged from 55.53-82.47 cm. TSS concentrations ranged from 0-7.0 mg/L in the surface and ranged from 0- 10.0 mg/L in 5 meters depth. At high tide down, sediment was settling and at the time of high tide, sediment mixed back.Keywords: Pare Bay, suspended solid, tidal range, tide.ABSTRAKKondisi perairan di Teluk Pare sangat berkaitan dengan mekanisme sirkulasi di Selat Makasar, Permasalahan yang terjadi di Teluk Pare salah satunya adalah tingginya tingkat kekeruhan dan rendahnya dinamika transport didalam teluk yang menyebabkan pendangkalan di beberapa bagian teluk. Tujuan dari penelitian ini adalah mengetahui karakteristik julat pasang surut dan pengaruhnya terhadap sebaran sedimen tersuspensi sebagai analisis proses sedimentasi dan pendangkalan di perairan Teluk Pare. Metode penelitian yang digunakan adalah deskriptif kuantitatif, metode penentuan lokasi titik pengambilan sampel air yaitu metode purposive sampling. Tipe pasang surut Teluk
International Nuclear Information System (INIS)
Baker, A.C.
1991-01-01
This book describes how large tides develop in particular places and how the energy could be extracted by building suitable barrages. The principal features of a barrage and possible methods of operation are described in detail. Although a tidal power barrage would be non-polluting, the resulting changes in the tidal regime would have important environmental effects. These are discussed together with the economics of tidal power. Methods of assessing the likely cost of electricity from any site are set out and applied to possible sites around the world. (author)
Numerical simulation of sediment deposition thickness at Beidaihe International Yacht Club
Directory of Open Access Journals (Sweden)
Cheng-gang Lu
2010-09-01
Full Text Available The finite element method (FEM was used to simulate sediment hydrodynamics at the Beidaihe International Yacht Club, and a two-dimensional model was established. The sediment movement and deposition were analyzed under many tidal conditions in conjunction with the hydrological regime of the Daihe River. The peak value of the sediment deposition thickness appears in the main channel and around the estuary. The sediment deposition thickness is essentially constant and relatively small in the project area. The sediment deposition thickness in the main channel, in the yachting area, and around the hotel is greater than the other areas in the project. Regular excavation and dredging of the channel is the best measure for mitigating the sedimentation.
Medical and Other Radioisotopes as Tracers in the Wastewater-River-Sediment Chain
Energy Technology Data Exchange (ETDEWEB)
Fischer, H. W.; Ulbrich, S.; Pittauerova, D.; Hettwig, B. [Institute of Environmental Physics, University of Bremen, Bremen (Germany)
2013-07-15
Medical, natural and other artificial radioisotopes have been followed on their pathway to river sediment employing gamma spectroscopy. Sampling points were situated at a local wastewater treatment plant (inflow, outflow and sludge) and along 70 km of a tidal river (bank sediment). Isotope entry points are assumed to be wastewater for medical isotopes like I-131 and Tc-99m, rain for natural Be-7, and soil erosion for fission generated Cs-137. Medical isotope data reflect the short term dynamics of medical usage, wastewater transport and treatment, and the river system. Be-7 data are influenced by the amount of rainfall on a short time scale, and by the size of the river catchment area and dilution due to tidal effects in the long term. Cs-137 values appear rather constant, behaving similarly to primordial K-40. In conclusion, the investigated radioisotopes offer a variety of possibilities to assess water and sediment dynamics. (author)
International Nuclear Information System (INIS)
Bowers, J.A.; Kretchmer, D.W.; Chimney, M.J.
1992-04-01
The Savannah River Site (SRS) encompasses 300 sq mi of the Atlantic Coastal Plain in west-central South Carolina. The Savannah River forms the western boundary of the site. Five major tributaries of the Savannah River -- upper Three Runs Creek, Four Mile Creek, Pen Branch, Steel Creek, and Lower Three Runs Creek -- drain the site. All but Upper Three Runs Creek receive, or in the past received, thermal effluents from nuclear production reactors. In 1985, L Lake, a 400-hectare cooling reservoir, was built on the upper reaches of Steel Creek to receive effluent from the restart of L-Reactor, and protect the lower reaches from thermal impacts. The Steel Creek Biological Monitoring Program was designed to meet envirorunental regulatory requirements associated with the restart of L-Reactor and complements the Biological Monitoring Program for L Lake. This extensive program was implemented to address portions of Section 316(a) of the Clean Water Act. The Department of Energy (DOE) must demonstrate that the operation of L-Reactor will not significantly alter the established aquatic ecosystems
Assessment of Heavy Metal Pollution in Sediment and Polychaete ...
African Journals Online (AJOL)
Metal pollution in the Mzinga creek mangrove stand was assessed and compared with a relatively pristine mangrove forest at Ras Dege in Dar es Salaam. The concentrations of cadmium, chromium, copper, lead and zinc in sediment and polychaete worms (Capitella sp.) were analyzed by ICP-AES and mercury was ...
Active Urbanization and Channel Adjustment in Apple Creek, Appleton, WI
Clark, J. J.
2002-12-01
Headwaters of the Apple Creek watershed have been and continue to be rapidly developed as part of the City of Appleton's long-term growth plan. Concurrent with early development, and prior to development over the past 4 years, two regional stormwater management facilities were constructed. Cross-sectional surveys and core transects were used to determine channel response to urbanization mitigated by stormwater management. The reach immediately downstream of the first pond complex has a narrow, but well established, wooded riparian zone and has not changed in size or shape over the past two years. An engineered reach approximately one mile downstream, however has exhibited widespread bed aggradation. Cross-sectional area decreased an average of 51% over the past four years. Despite the use of sediment and erosion control BMPs, sediment concentrations exceeding 1000 mg/L during base flow are not uncommon downstream of construction sites adjacent to the stream. The artificially widened channel, a reduction in stream gradient, and the backwater effect from downstream ponds caused much of this sediment to remain within the engineered reach. It is estimated that approximately 21,000 Mg of sediment is stored in this mile-long reach. As this sediment migrates downstream, the forebay of the second set of stormwater ponds will begin to fill, reducing storage capacity and thereby limiting its effectiveness in mitigating peak discharges and sequestering nutrients.
Pivato, M.; Carniello, L.; Gardner, J.; Silvestri, S.; Marani, M.
2018-03-01
In the present study, we investigate the energy flux at the sediment-water interface and the relevance of the heat exchanged between water and sediment for the water temperature dynamics in shallow coastal environments. Water and sediment temperature data collected in the Venice lagoon show that, in shallow, temperate lagoons, temperature is uniform within the water column, and enabled us to estimate the net heat flux at the sediment-water interface. We modeled this flux as the sum of a conductive component and of the solar radiation reaching the bottom, finding the latter being negligible. We developed a "point" model to describe the temperature dynamics of the sediment-water continuum driven by vertical energy transfer. We applied the model considering conditions characterized by negligible advection, obtaining satisfactory results. We found that the heat exchange between water and sediment is crucial for describing sediment temperature but plays a minor role on the water temperature.
Humin to Human: Organic carbon, sediment, and water fluxes along river corridors in a changing world
Energy Technology Data Exchange (ETDEWEB)
Sutfin, Nicholas Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-11-20
This is a presentation with slides on What does it mean to be human? ...humin?; River flow and Hydrographs; Snake River altered hydrograph (Marston et al., 2005); Carbon dynamics are important in rivers; Rivers and streams as carbon sink; Reservoirs for organic carbon; Study sites in Colorado; River morphology; Soil sample collection; Surveys at RMNP; Soil organic carbon content at RMNP; Abandoned channels and Cutoffs; East River channel migration and erosion; Linking hydrology to floodplain sediment flux; Impact of Extreme Floods on Floodplain Sediment; Channel Geometry: RMNP; Beavers dams and multithread channels; Geomorphology and carbon in N. St. Vrain Creek; Geomorphology and carbon along the East River; Geomorphology and carbon in N. St. Vrain Creek; San Marcos River, etc.
Eppinger, Robert G.; Briggs, Paul H.; Brown, Zoe Ann; Crock, James G.; Meier, Allen; Theodorakos, Peter M.; Wilson, Stephen A.
2001-01-01
In 1996, the U.S. Geological Survey conducted a reconnaissance baseline geochemical study in central Idaho. The purpose of the baseline study was to establish a 'geochemical snapshot' of the area, as a datum for monitoring future change in the geochemical landscape, whether natural or human-induced. This report presents the methology, analytical results, and sample descriptions for water, sediment, and heavy-mineral concentrate samples collected during this geochemical investigation. In the summer of 2000, the Clear Creek, Little Pistol, and Shellrock wildfires swept across much of the area that was sampled. Thus, these data represent a pre-fire baseline geochemical dataset. A 2001 post- fire study is planned and will involve re-sampling of the pre-fire baseline sites, to allow for pre- and post-fire comparison.
2010-07-13
... TENNESSEE VALLEY AUTHORITY Northeastern Tributary Reservoirs Land Management Plan, Beaver Creek...-managed public land on Beaver Creek, Clear Creek, Boone, Fort Patrick Henry, South Holston, Watauga, and... Proposed Land Use Alternative) identified in the final environmental impact statement (FEIS). Under the...
Exploitation of tidal power in the Bay of Cadiz: ancient tidal mills
Directory of Open Access Journals (Sweden)
José J. Alonso del Rosario
2006-03-01
Full Text Available Tidal mills were the main industrial activity in the Bay of Cadiz for centuries. They were the last step in the production of salt and flour made by grinding grains. They were installed along the shallow channels, called “caños”, around the Bay, where the frictional and geometrical effects are very strong. The authors have analyzed the propagation of the semidiurnal tidal waves along the Caño de Sancti Petri and the available tidal power in the area. The ancient tidal mills were located where the available tidal potential energy is highest, which ensured productivity for grinding salt and wheat in ancient times. Some considerations about the possibility of installing tidal power plants in the Bay of Cadiz now are given, which show that it could be a real and renewal alternative source of energy for the area.
Dai, Peng; Zhang, Jisheng; Zheng, Jinhai
2017-12-01
The Taiwan Strait has recently been proposed as a promising site for dynamic tidal power systems because of its shallow depth and strong tides. Dynamic tidal power is a new concept for extracting tidal potential energy in which a coast-perpendicular dike is used to create water head and generate electricity via turbines inserted in the dike. Before starting such a project, the potential power output and hydrodynamic impacts of the dike must be assessed. In this study, a two-dimensional numerical model based on the Delft3D-FLOW module is established to simulate tides in China. A dike module is developed to account for turbine processes and estimate power output by integrating a special algorithm into the model. The domain decomposition technique is used to divide the computational zone into two subdomains with grid refinement near the dike. The hydrodynamic processes predicted by the model, both with and without the proposed construction, are examined in detail, including tidal currents and tidal energy flux. The predicted time-averaged power yields with various opening ratios are presented. The results show that time-averaged power yield peaks at an 8% opening ratio. For semidiurnal tides, the flow velocity increases in front of the head of the dike and decreases on either side. For diurnal tides, these changes are complicated by the oblique incidence of tidal currents with respect to the dike as well as by bathymetric features. The dike itself blocks the propagation of tidal energy flux.
Geochemical Model And Normalization For Heavy Metals In The Bottom Sediments, Dubai, UAE.
El Sammak, A.A. [عمرو عبدالعزيز السماك
1999-01-01
Dubai creek can be considered as the focal point of Dubai. It has great importance for trading and aesthetic values. Total and leachable heavy metals (Cd, Co, Ni, Pb and Zn), organic carbon and total carbonate were studied in the bottom sediments of the creek. Pollution Load Index, statistical analysis, were used in order to quantify the pollution load as well as to discriminate the data into significant groups. Normalization of the data using organic carbon and total carbonate was done in or...
Cravotta,, Charles A.
2004-01-01
This report assesses the contaminant loading, effects to receiving streams, and possible remedial alternatives for abandoned mine drainage (AMD) within the Mahanoy Creek Basin in east-central Pennsylvania. The Mahanoy Creek Basin encompasses an area of 157 square miles (407 square kilometers) including approximately 42 square miles (109 square kilometers) underlain by the Western Middle Anthracite Field. As a result of more than 150 years of anthracite mining in the basin, ground water, surface water, and streambed sediments have been adversely affected. Leakage from streams to underground mines and elevated concentrations (above background levels) of acidity, metals, and sulfate in the AMD from flooded underground mines and (or) unreclaimed culm (waste rock) degrade the aquatic ecosystem and impair uses of the main stem of Mahanoy Creek from its headwaters to its mouth on the Susquehanna River. Various tributaries also are affected, including North Mahanoy Creek, Waste House Run, Shenandoah Creek, Zerbe Run, and two unnamed tributaries locally called Big Mine Run and Big Run. The Little Mahanoy Creek and Schwaben Creek are the only major tributaries not affected by mining. To assess the current hydrological and chemical characteristics of the AMD and its effect on receiving streams, and to identify possible remedial alternatives, the U.S. Geological Survey (USGS) began a study in 2001, in cooperation with the Pennsylvania Department of Environmental Protection and the Schuylkill Conservation District. Aquatic ecological surveys were conducted by the USGS at five stream sites during low base-flow conditions in October 2001. Twenty species of fish were identified in Schwaben Creek near Red Cross, which drains an unmined area of 22.7 square miles (58.8 square kilometers) in the lower part of the Mahanoy Creek Basin. In contrast, 14 species of fish were identified in Mahanoy Creek near its mouth at Kneass, below Schwaben Creek. The diversity and abundance of fish
Measuring the role of seagrasses in regulating sediment surface elevation
Potouroglou, Maria
2017-09-13
Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human welfare as well as ecological integrity. In common with the other \\'blue carbon\\' habitats (mangroves and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in mangroves and tidal marshes has been gained by monitoring a wide range of different sites, located in varying hydrogeomorphological conditions over long periods. In contrast, similar evidence for seagrasses is sparse; the present study is a contribution towards filling this gap. Surface elevation change pins were deployed in four locations, Scotland, Kenya, Tanzania and Saudi Arabia, in both seagrass and unvegetated control plots in the low intertidal and shallow subtidal zone. The presence of seagrass had a highly significant, positive impact on surface elevation at all sites. Combined data from the current work and the literature show an average difference of 31 mm per year in elevation rates between vegetated and unvegetated areas, which emphasizes the important contribution of seagrass in facilitating sediment surface elevation and reducing erosion. This paper presents the first multi-site study for sediment surface elevation in seagrasses in different settings and species.
Measuring the role of seagrasses in regulating sediment surface elevation
Potouroglou, Maria; Bull, James C.; Krauss, Ken W.; Kennedy, Hilary A.; Fusi, Marco; Daffonchio, Daniele; Mangora, Mwita M.; Githaiga, Michael N.; Diele, Karen; Huxham, Mark
2017-01-01
Seagrass meadows provide numerous ecosystem services and their rapid global loss may reduce human welfare as well as ecological integrity. In common with the other ‘blue carbon’ habitats (mangroves and tidal marshes) seagrasses are thought to provide coastal defence and encourage sediment stabilisation and surface elevation. A sophisticated understanding of sediment elevation dynamics in mangroves and tidal marshes has been gained by monitoring a wide range of different sites, located in varying hydrogeomorphological conditions over long periods. In contrast, similar evidence for seagrasses is sparse; the present study is a contribution towards filling this gap. Surface elevation change pins were deployed in four locations, Scotland, Kenya, Tanzania and Saudi Arabia, in both seagrass and unvegetated control plots in the low intertidal and shallow subtidal zone. The presence of seagrass had a highly significant, positive impact on surface elevation at all sites. Combined data from the current work and the literature show an average difference of 31 mm per year in elevation rates between vegetated and unvegetated areas, which emphasizes the important contribution of seagrass in facilitating sediment surface elevation and reducing erosion. This paper presents the first multi-site study for sediment surface elevation in seagrasses in different settings and species.
2013-10-22
... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 3730-005] Salmon Creek Hydroelectric Company, Salmon Creek Hydroelectric Company, LLC; Notice of Transfer of Exemption 1. By letter filed September 23, 2013, Salmon Creek Hydroelectric Company informed the Commission that they have...
Bathymetric survey of Carroll Creek Tributary to Lake Tuscaloosa, Tuscaloosa County, Alabama, 2010
Lee, K.G.; Kimbrow, D.R.
2011-01-01
The U.S. Geological Survey, in cooperation with the City of Tuscaloosa, conducted a bathymetric survey of Carroll Creek, on May 12-13, 2010. Carroll Creek is one of the major tributaries to Lake Tuscaloosa and contributes about 6 percent of the surface drainage area. A 3.5-mile reach of Carroll Creek was surveyed to prepare a current bathymetric map, determine storage capacities at specified water-surface elevations, and compare current conditions to historical cross sections. Bathymetric data were collected using a high-resolution interferometric mapping system consisting of a phase-differencing bathymetric sonar, navigation and motion-sensing system, and a data acquisition computer. To assess the accuracy of the interferometric mapping system and document depths in shallow areas of the study reach, an electronic total station was used to survey 22 cross sections spaced 50 feet apart. The data were combined and processed and a Triangulated Irregular Network (TIN) and contour map were generated. Cross sections were extracted from the TIN and compared with historical cross sections. Between 2004 and 2010, the area (cross section 1) at the confluence of Carroll Creek and the main run of LakeTuscaloosa showed little to no change in capacity area. Another area (cross section 2) showed a maximum change in elevation of 4 feet and an average change of 3 feet. At the water-surface elevation of 224 feet (National Geodetic Vertical Datum of 1929), the cross-sectional area has changed by 260 square feet for a total loss of 28 percent of cross-sectional storage area. The loss of area may be attributed to sedimentation in Carroll Creek and (or) the difference in accuracy between the two surveys.
The Role of Infragravity Waves in Near-Bed Cross-Shore Sediment Flux in the Breaker Zone
Directory of Open Access Journals (Sweden)
Samantha Kularatne
2014-08-01
Full Text Available Results from a series of field experiments, conducted to investigate the influence of infragravity waves (from wave groups, ripple type and location relative to the breaker line on cross-shore suspended sediment flux close to the sea bed in nearshore environments, are presented. The field data were collected from Cable Beach (Broome and Mullaloo Beach in Western Australia and Chilaw in Sri Lanka. These beaches experience different incident wave, tidal and morphological conditions, with Cable Beach having a 10-m spring tidal range, whilst the other two beaches have tidal ranges <1.0 m. Measurements included simultaneous records of surface elevation, two-dimensional horizontal current velocities and suspended sediment concentrations, together with half-hourly observations of the seabed topography. Although most of the data sets were obtained just outside of the surf zone, a few results from inside of the surf zone were also included. A significant correlation between wave groups and suspended sediment concentration was found at all of the measurement sites, either with or without bed ripples. The direction and magnitude of cross-shore suspended sediment flux varied with location with respect to the breaker line; however, other parameters, such as bed ripples and velocity skewness, could have influenced this result. In Broome, where the measurement location with respect to the breaker line varied with the tidal cycle, the cross-shore sediment flux due to swell waves was shoreward inside and just outside of the surf zone and seaward farther offshore of the breaker line. Further, sediment flux due to swell waves was onshore when the seabed was flat and offshore over post-vortex ripples. Sediment flux due to swell waves was onshore when the normalised velocity skewness towards the shore was high (positive; the flux was offshore when the skewness was lower, but positive, suggesting the influence of other parameters, such as ripples and grain size. The
Gillespie, Jaimie; Noe, Gregory; Hupp, Cliff R.; Gellis, Allen; Schenk, Edward R.
2018-01-01
Floodplains and streambanks can positively and negatively influence downstream water quality through interacting geomorphic and biogeochemical processes. Few studies have measured those processes in agricultural watersheds. We measured inputs (floodplain sedimentation and dissolved inorganic loading), cycling (floodplain soil nitrogen [N] and phosphorus [P] mineralization), and losses (bank erosion) of sediment, N, and P longitudinally in stream reaches of Smith Creek, an agricultural watershed in the Valley and Ridge physiographic province. All study reaches were net depositional (floodplain deposition > bank erosion), had high N and P sedimentation and loading rates to the floodplain, high soil concentrations of N and P, and high rates of floodplain soil N and P mineralization. High sediment, N, and P inputs to floodplains are attributed to agricultural activity in the region. Rates of P mineralization were much greater than those measured in other studies of nontidal floodplains that used the same method. Floodplain connectivity and sediment deposition decreased longitudinally, contrary to patterns in most watersheds. The net trapping function of Smith Creek floodplains indicates a benefit to water quality. Further research is needed to determine if future decreases in floodplain deposition, continued bank erosion, and the potential for nitrate leaching from nutrient-enriched floodplain soils could pose a long-term source of sediment and nutrients to downstream rivers.
Big Bayou Creek and Little Bayou Creek Watershed Monitoring Program
Energy Technology Data Exchange (ETDEWEB)
Kszos, L.A.; Peterson, M.J.; Ryon; Smith, J.G.
1999-03-01
Biological monitoring of Little Bayou and Big Bayou creeks, which border the Paducah Site, has been conducted since 1987. Biological monitoring was conducted by University of Kentucky from 1987 to 1991 and by staff of the Environmental Sciences Division (ESD) at Oak Ridge National Laboratory (ORNL) from 1991 through March 1999. In March 1998, renewed Kentucky Pollutant Discharge Elimination System (KPDES) permits were issued to the US Department of Energy (DOE) and US Enrichment Corporation. The renewed DOE permit requires that a watershed monitoring program be developed for the Paducah Site within 90 days of the effective date of the renewed permit. This plan outlines the sampling and analysis that will be conducted for the watershed monitoring program. The objectives of the watershed monitoring are to (1) determine whether discharges from the Paducah Site and the Solid Waste Management Units (SWMUs) associated with the Paducah Site are adversely affecting instream fauna, (2) assess the ecological health of Little Bayou and Big Bayou creeks, (3) assess the degree to which abatement actions ecologically benefit Big Bayou Creek and Little Bayou Creek, (4) provide guidance for remediation, (5) provide an evaluation of changes in potential human health concerns, and (6) provide data which could be used to assess the impact of inadvertent spills or fish kill. According to the cleanup will result in these watersheds [Big Bayou and Little Bayou creeks] achieving compliance with the applicable water quality criteria.
International Nuclear Information System (INIS)
Rutherford, L.G.; Cherry, D.S.; Dobbs, M.G.; Cairns, J. Jr.; Zipper, C.E.
1995-01-01
The toxic constituents of abandoned mined land (AML) discharges (acidic pH, heavy metals, total suspended solids) are extremely toxic to aquatic life . Studies were undertaken to ascertain environmental impacts to the upper Powell River, Lee and Wise Counties, Va. These impacts included disruptions in physical water quality, sediment quality, altered benthic macroinvertebrate assemblages, and toxicity of the water column and sediments from short-term impairment bioassays, and the potential to bioaccumulate selected metals (Al, Fe, Mn, P, Zn, Cu, Mg, S, Ni, Cd) by periphyton and resident bivalves. Water chemistry and macroinvertebrate assemblages were collected at upstream control, just below acid mine drainage and other downstream sites. Selected trace metal concentrations (Al, Fe, Mn, P, Zn, Cu, Mg, S, Ni, Cd) were determined for water, sediment and resident bivalves using ICP-AES. Acidic pH ranged from 2.15--3.3 at three AML-influenced seeps and varied from 6.4--8.0 at reference stations. At one AML-influenced creek, acidic pH conditions worsened from summer to fall and eradicated aquatic life throughout a 1.5 km stretch of that creek as it flowed into another creek. An additional dilution of 3.4 km in the second creek was needed to nearly neutralize the acidic pH problem. Conductivity (umhos/cm) ranged from 32--278 at reference sites and from 245--4,180 at AML-impact sites. Benthic macroinvertebrate abundance and taxon richness were essentially eliminated in the seeps or reached numbers of 1 -3 taxa totaling < 10 organisms relative to reference areas where richness values were 12--17 and comprised 300--977 organisms. Concentrations of Fe, Al, Mg and Cu and Zn were highest in the environmentally stressed stations of low pH and high conductivity relative to the reference stations. Iron was, by far, the element in highest concentration followed by Al and Mg
Radioactive fallout reconstruction from contemporary measurements of reservoir sediments
International Nuclear Information System (INIS)
Krey, P.W.; Heit, M.; Miller, K.M.
1990-01-01
The temporal history of atmospheric deposition to a watershed area can be preserved in the sediment of a lake or reservoir that is supplied by the watershed. The 137 Cs and isotopic Pu concentrations with depth were determined in the sediments of two reservoirs, Enterprise and Deer Creek, which are located in widely separated regions of the state of Utah. Our data not only reconstruct the history of the total radioactive fallout in the area, but also permit estimating the contributions from global sources and from the Nevada Test Site detonations in the 1950s
Stark, J.; Smolders, S.; Meire, P.; Temmerman, S.
2017-11-01
effects of tidal prism decrease upstream and tidal prism increase downstream of additional storage areas, our model results indicate a reduction in tidal prism far downstream of intertidal storage areas as a result of a decreasing tidal range. This study may assist estuarine managers in assessing the impact of marsh restoration and managed shoreline realignment projects, as well as with the morphological management of estuaries through dredging and disposal of sediment on intertidal areas.
Thorne, Karen M.; Buffington, Kevin J.; Swanson, Kathleen; Takekawa, John Y.
2013-01-01
Tidal marshes are dynamic ecosystems, which are influenced by oceanic and freshwater processes and daily changes in sea level. Projected sea-level rise and changes in storm frequency and intensity will affect tidal marshes by altering suspended sediment supply, plant communities, and the inundation duration and depth of the marsh platform. The objective of this research was to evaluate if regional weather conditions resulting in low-pressure storms changed tidal conditions locally within three tidal marshes. We hypothesized that regional storms will increase sea level heights locally, resulting in increased inundation of the tidal marsh platform and plant communities. Using site-level measurements of elevation, plant communities, and water levels, we present results from two storm events in 2010 and 2011 from the San Francisco Bay Estuary (SFBE), California, USA. The January 2010 storm had the lowest recorded sea level pressure in the last 30 years for this region. During the storm episodes, the duration of tidal marsh inundation was 1.8 and 3.1 times greater than average for that time of year, respectively. At peak storm surges, over 65% in 2010 and 93% in 2011 of the plant community was under water. We also discuss the implications of these types of storms and projected sea-level rise on the structure and function of the tidal marshes and how that will impact the hydro-geomorphic processes and marsh biotic communities.
The distribution and tapping tidal energy
Directory of Open Access Journals (Sweden)
Zygmunt Kowalik
2004-09-01
Full Text Available Tidal power along tidal shores has been used for centuries to run small tidal mills. Generating electricity by tapping tidal power proved to be very successful only in the last century through the tidal power plant constructed in 1967 in La Rance, France. This used a large barrier to generate the sea level head necessary for driving turbines. Construction of such plants evolved very slowly because of prohibitive costs and concerns about the environmental impact. Developments in the construction of small, efficient and inexpensive underwater turbines admit the possibility of small scale operations that will use local tidal currents to bring electricity to remote locations. Since the generation of such electricity is concerned with the tidal energy in local water bodies, it is important to understand the site-specific energy balance, i.e., the energy flowing in through open boundaries, and the energy generated and dissipated within the local domain. The question is how to tap the tidal energy while keeping possible changes in the present tidal regimes to a minimum. The older approach of constructing barrages may still be quite useful in some locations. The basics of such tidal power plants constructed in a small bay are analyzed in order to understand the principal parameter for tidal plant evaluation, i.e., the power produced. The new approach is to place turbines - devices similar to windmills - in the pathway of tidal currents. Theoretically, the amount of power available by such turbines for electricity generation is proportional to the water density and velocity cubed of the tidal flow. The naturally dissipated tidal power due to bottom friction forces is also proportional to the cube of the velocity. Because of this similarity, the exploitation of tidal energy can be directed to reinvesting the naturally dissipated power into tidal power for the generation of electricity. This approach to tidal power exploitation is better tuned
From Globular Clusters to Tidal Dwarfs: Structure Formation in Tidal Tails
Knierman, K.; Hunsberger, S.; Gallagher, S.; Charlton, J.; Whitmore, B.; Hibbard, J.; Kundu, A.; Zaritsky, D.
1999-12-01
Galaxy interactions trigger star formation in tidal debris. How does this star formation depend on the local and global physical conditions? Using WFPC2/HST images, we investigate the range of structure within tidal tails of four classic ``Toomre Sequence'' mergers: NGC 4038/9 (``Antennae''), NGC 7252 (``Atoms for Peace''), NGC 3921, and NGC 3256. These tails contain a variety of stellar associations with sizes from globular clusters up to dwarf Irregulars. We explore whether there is a continuum between the two extremes. Our eight fields sample seven tidal tails at a variety of stages in the evolutionary sequence. Some of these tails are rich in HI while others are HI poor. Large tidal dwarfs are embedded in three of the tails. Using V and I WFPC2 images, we measure luminosities and colors of substructures within the tidal tails. The properties of globular cluster candidates in the tails will be contrasted with those of the hundreds of young clusters in the central regions of these mergers. We address whether globular clusters form and survive in the tidal tails and whether tidal dwarfs are composed of only young stars. By comparing the properties of structures in the tails of the four mergers with different ages, we examine systematic evolution of structure along the evolutionary sequence and as a function of HI content. We acknowledge support from NASA through STScI, and from NSF for an REU supplement for Karen Knierman.
Canyon Creek: A late Pleistocene vertebrate locality in interior Alaska
Weber, Florence R.; Hamilton, Thomas D.; Hopkins, David M.; Repenning, Charles A.; Haas, Herbert
1981-09-01
The Canyon Creek vertebrate-fossil locality is an extensive road cut near Fairbanks that exposes sediments that range in age from early Wisconsin to late Holocene. Tanana River gravel at the base of the section evidently formed during the Delta Glaciation of the north-central Alaska Range. Younger layers and lenses of fluvial sand are interbedded with arkosic gravel from Canyon Creek that contains tephra as well as fossil bones of an interstadial fauna about 40,000 years old. Solifluction deposits containing ventifacts, wedge casts, and rodent burrows formed during a subsequent period of periglacial activity that took place during the maximum phase of Donnelly Glaciation about 25,000-17,000 years ago. Overlying sheets of eolian sand are separated by a 9500-year-old paleosol that may correlate with a phase of early Holocene spruce expansion through central Alaska. The Pleistocene fauna from Canyon Creek consists of rodents (indicated by burrows), Mammuthus primigenius (woolly mammoth), Equus lambei (Yukon wild ass), Camelops hesternus (western camel), Bison sp. cf. B. crassicornis (large-horned bison), Ovis sp. cf. O. dalli (mountain sheep), Canis sp. cf. C. lupus (wolf), Lepus sp. cf. L. othus or L. arcticus (tundra hare), and Rangifer sp. (caribou). This assemblage suggests an open landscape in which trees and tall shrubs were either absent or confined to sheltered and moist sites. Camelops evidently was present in eastern Beringia during the middle Wisconsin interstadial interval but may have disappeared during the following glacial episode. The stratigraphic section at Canyon Creek appears to demonstrate that the Delta Glaciation of the north-central Alaska Range is at least in part of early Wisconsin age and was separated from the succeeding Donnelly Glaciation by an interstadial rather than interglacial episode.
Multiscale physical processes of fine sediment in an estuary
Wan, Y.
2015-01-01
This study presented in this book investigates micro- and macro- scale physical processes of a large-scale fine sediment estuarine system with a moderate tidal range as well as a highly seasonal-varying freshwater inflow. Based on a series measured, experimented and modeled results, the research
Schaub, B E M; van Gemerden, H
1996-01-01
Enumeration of the functional groups of sulfur bacteria was performed in the sediments in the Bassin d'Arcachon, a mesotidal lagoon with strong tidal currents and dominant populations of seagrass (Zostera noltii), and in the Etang du Prevost, a shallow lagoon with moderate tidal fluctuations and
Energy Technology Data Exchange (ETDEWEB)
Bowers, J.A. [Westinghouse Savannah River Co., Aiken, SC (United States); Toole, M.A.; van Duyn, Y. [Normandeau Associates Inc., New Ellenton, SC (United States)
1992-02-01
The Savannah River Site (SRS) encompasses 300 sq mi of the Atlantic Coastal Plain in west-central South Carolina. Five major tributaries of the Savannah River -- Upper Three Runs Creek, Four Mile Creek, Pen Branch, Steel Creek, and Lower Three Runs Creek -- drain the site. In 1985, L Lake, a 400-hectare cooling reservoir, was built on the upper reaches of Steel Creek to receive effluent from the restart of L-Reactor and to protect the lower reaches from thermal impacts. The Steel Creek Biological Monitoring Program was designed to assess various components of the system and identify and changes due to the operation of L-Reactor or discharge from L Lake. An intensive ecological assessment program prior to the construction of the lake provided baseline data with which to compare data accumulated after the lake was filled and began discharging into the creek. The Department of Energy must demonstrate that the operation of L-Reactor will not significantly alter the established aquatic ecosystems. This report summarizes the results of six years` data from Steel Creek under the L-Lake/Steel Creek Monitoring Program. L Lake is discussed separately from Steel Creek in Volumes NAI-SR-138 through NAI-SR-143.
International Nuclear Information System (INIS)
Bowers, J.A.; Toole, M.A.; van Duyn, Y.
1992-02-01
The Savannah River Site (SRS) encompasses 300 sq mi of the Atlantic Coastal Plain in west-central South Carolina. Five major tributaries of the Savannah River -- Upper Three Runs Creek, Four Mile Creek, Pen Branch, Steel Creek, and Lower Three Runs Creek -- drain the site. In 1985, L Lake, a 400-hectare cooling reservoir, was built on the upper reaches of Steel Creek to receive effluent from the restart of L-Reactor and to protect the lower reaches from thermal impacts. The Steel Creek Biological Monitoring Program was designed to assess various components of the system and identify and changes due to the operation of L-Reactor or discharge from L Lake. An intensive ecological assessment program prior to the construction of the lake provided baseline data with which to compare data accumulated after the lake was filled and began discharging into the creek. The Department of Energy must demonstrate that the operation of L-Reactor will not significantly alter the established aquatic ecosystems. This report summarizes the results of six years' data from Steel Creek under the L-Lake/Steel Creek Monitoring Program. L Lake is discussed separately from Steel Creek in Volumes NAI-SR-138 through NAI-SR-143
Xu, Yan; Sun, Xiangli; Zhang, Qiqiong; Li, Xiuzhen; Yan, Zhongzheng
2018-05-30
Tidal flat elevation in the estuarine wetland determines the tidal flooding time and flooding frequency, which will inevitably affect the formation of iron plaque and accumulations of heavy metals (HMs) in wetland plants. The present study investigated the formation of iron plaque and HM's (copper, zinc, lead, and chromium) accumulation in S. alterniflora, a typical estuarine wetland species, at different tidal flat elevations (low, middle and high) in filed and at different time (3, 6, 9, 12 h per day) of waterlogging treatment in greenhouse conditions. Results showed that the accumulation of copper, zinc, lead, and chromium in S. alterniflora was proportional to the exchangeable fraction of these metals in the sediments, which generally increased with the increase of waterlogging time, whereas the formations of iron plaque in roots decreased with the increase of waterlogging time. Under field conditions, the uptake of copper and zinc in the different parts of the plants generally increased with the tidal levels despite the decrease in the metals' exchangeable fraction with increasing tidal levels. The formation of iron plaque was found to be highest in the middle tidal positions and significantly lower in low and high tidal positions. Longer waterlogging time increased the metals' accumulation but decreased the formation of iron plaque in S. alterniflora. The binding of metal ions on iron plaque helped impede the uptake and accumulation of copper and chromium in S. alterniflora. Copyright © 2018 Elsevier Inc. All rights reserved.
Near bed suspended sediment flux by single turbulent events
Amirshahi, Seyed Mohammad; Kwoll, Eva; Winter, Christian
2018-01-01
The role of small scale single turbulent events in the vertical mixing of near bed suspended sediments was explored in a shallow shelf sea environment. High frequency velocity and suspended sediment concentration (SSC; calibrated from the backscatter intensity) were collected using an Acoustic Doppler Velocimeter (ADV). Using quadrant analysis, the despiked velocity time series was divided into turbulent events and small background fluctuations. Reynolds stress and Turbulent Kinetic Energy (TKE) calculated from all velocity samples, were compared to the same turbulent statistics calculated only from velocity samples classified as turbulent events (Reevents and TKEevents). The comparison showed that Reevents and TKEevents was increased 3 and 1.6 times, respectively, when small background fluctuations were removed and that the correlation with SSC for TKE could be improved through removal of the latter. The correlation between instantaneous vertical turbulent flux (w ‧) and SSC fluctuations (SSC ‧) exhibits a tidal pattern with the maximum correlation at peak ebb and flood currents, when strong turbulent events appear. Individual turbulent events were characterized by type, strength, duration and length. Cumulative vertical turbulent sediment fluxes and average SSC associated with individual turbulent events were calculated. Over the tidal cycle, ejections and sweeps were the most dominant events, transporting 50% and 36% of the cumulative vertical turbulent event sediment flux, respectively. Although the contribution of outward interactions to the vertical turbulent event sediment flux was low (11%), single outward interaction events were capable of inducing similar SSC ‧ as sweep events. The results suggest that on time scales of tens of minutes to hours, TKE may be appropriate to quantify turbulence in sediment transport studies, but that event characteristics, particular the upward turbulent flux need to be accounted for when considering sediment transport
Vazquez, Jorge A.; Lidzbarski, Marsha I.
2012-12-01
Sediments of the Wilson Creek Formation surrounding Mono Lake preserve a high-resolution archive of glacial and pluvial responses along the eastern Sierra Nevada due to late Pleistocene climate change. An absolute chronology for the Wilson Creek stratigraphy is critical for correlating the paleoclimate record to other archives in the western U.S. and the North Atlantic region. However, multiple attempts to date the Wilson Creek stratigraphy using carbonates and tephras yield discordant results due to open-system effects and radiocarbon reservoir uncertainties as well as abundant xenocrysts. New ion microprobe 238U-230Th dating of the final increments of crystallization recorded by allanite and zircon autocrysts from juvenile pyroclasts yield ages that effectively date eruption of key tephra beds and delimit the timing of basal Wilson Creek sedimentation to the interval between 26.8±2.1 and 61.7±1.9 ka. Tephra (Ash 15) erupted during the geomagnetic excursion originally designated the Mono Lake excursion yields an age of 40.8±1.9 ka, indicating that the event is instead the Laschamp excursion. The new ages support a depositional chronology from magnetostratigraphy that indicates quasi-synchronous glacial and hydrologic responses in the Sierra Nevada and Mono Basin to regional climate change, with intervals of lake filling and glacial-snowpack melting that are in phase with peaks in spring insolation.
Vazquez, Jorge A.; Lidzbarski, Marsha I.
2012-01-01
Sediments of the Wilson Creek Formation surrounding Mono Lake preserve a high-resolution archive of glacial and pluvial responses along the eastern Sierra Nevada due to late Pleistocene climate change. An absolute chronology for the Wilson Creek stratigraphy is critical for correlating the paleoclimate record to other archives in the western U.S. and the North Atlantic region. However, multiple attempts to date the Wilson Creek stratigraphy using carbonates and tephras yield discordant results due to open-system effects and radiocarbon reservoir uncertainties as well as abundant xenocrysts. New ion microprobe 238U-230Th dating of the final increments of crystallization recorded by allanite and zircon autocrysts from juvenile pyroclasts yield ages that effectively date eruption of key tephra beds and delimit the timing of basal Wilson Creek sedimentation to the interval between 26.8±2.1 and 61.7±1.9 ka. Tephra (Ash 15) erupted during the geomagnetic excursion originally designated the Mono Lake excursion yields an age of 40.8±1.9 ka, indicating that the event is instead the Laschamp excursion. The new ages support a depositional chronology from magnetostratigraphy that indicates quasi-synchronous glacial and hydrologic responses in the Sierra Nevada and Mono Basin to regional climate change, with intervals of lake filling and glacial-snowpack melting that are in phase with peaks in spring insolation.
Senior, Lisa A.; Koerkle, Edward H.
2003-01-01
The Christina River Basin drains 565 square miles (mi2) in Pennsylvania, Maryland, and Delaware. Water from the basin is used for recreation, drinking water supply, and to support aquatic life. The Christina River Basin includes the major subbasins of Brandywine Creek, White Clay Creek, and Red Clay Creek. The White Clay Creek is the second largest of the subbasins and drains an area of 108 mi2. Water quality in some parts of the Christina River Basin is impaired and does not support designated uses of the streams. A multi-agency water-quality management strategy included a modeling component to evaluate the effects of point and nonpoint-source contributions of nutrients and suspended sediment on stream water quality. To assist in non point-source evaluation, four independent models, one for each of the three major subbasins and for the Christina River, were developed and calibrated using the model code Hydrological Simulation Program—Fortran (HSPF). Water-quality data for model calibration were collected in each of the four main subbasins and in smaller subbasins predominantly covered by one land use following a nonpoint-source monitoring plan. Under this plan, stormflow and base- flow samples were collected during 1998 at two sites in the White Clay Creek subbasin and at nine sites in the other subbasins.The HSPF model for the White Clay Creek Basin simulates streamflow, suspended sediment, and the nutrients, nitrogen and phosphorus. In addition, the model simulates water temperature, dissolved oxygen, biochemical oxygen demand, and plankton as secondary objectives needed to support the sediment and nutrient simulations. For the model, the basin was subdivided into 17 reaches draining areas that ranged from 1.37 to 13 mi2. Ten different pervious land uses and two impervious land uses were selected for simulation. Land-use areas were determined from 1995 land-use data. The predominant land uses in the White Clay Creek Basin are agricultural, forested