Sample records for subglacial drainage system

  1. Structure, morphology and water flux of a subglacial drainage system, Midtdalsbreen, Norway

    NARCIS (Netherlands)

    Willis, I.C.; Fitzsimmons, C.D.; Melvold, K.; Andreassen, L.M.; Giesen, R.H.|info:eu-repo/dai/nl/304831603


    Digital elevation models of the surface and bed of Midtdalsbreen, Norway are used to calculate subglacial hydraulic potential and infer drainage system structure for a series of subglacial water pressure assumptions ranging from atmospheric to ice overburden. A distributed degree-day model is used

  2. Fast flow of Jakobshavn Isbræ and its subglacial drainage system (United States)

    Werder, M. A.; Joughin, I. R.


    Jakobshavn Isbræ and many other outlet glaciers of present and past ice sheets lie in deep troughs which often have several overdeepened sections. The subglacial drainage system of such glaciers is heavily influenced by two effects caused by the pressure dependence of the melting point of water. The melting point decreases with increasing water pressure, this enhances wall-melt in downward sloping channels and diminishes wall-melt in upward sloping channels. Thus the first effect is the well known shutdown of channels on steep adverse bed slopes of overdeepenings and the associated high water pressure/low effective pressure. The second effect is a 2D effect and has not received much/any attention so far: the orientation of a channel will be deflected from the direction of the (negative) hydraulic potential gradient (which drives the water flow) towards the steepest slope of the bed. This leads to the enhanced formation of side channels dipping into the trough at about a 45° angle. This efficient connection between the margin and the trough equalizes the hydraulic potential, again leading to higher water pressure in the trough. We investigate these two effects with the 2D subglacial drainage system model GlaDS using Jakobshavn Isbræ as an example. We compare model runs with the pressure melt term disabled and enabled. With the term disabled the main channel situated in the trough is continuous and produces a large depression in the hydraulic potential and consequently high effective pressure in the trough (1-2MPa). Conversely, with the term enabled the main channel becomes discontinuous on steep adverse bed slopes and many side channels form on the margins of the trough. This leads to a hydraulic potential in the trough which is higher than in the surrounding area and consequently the effective pressure is low (0-1MPa). Low effective pressure leads to reduced basal drag and thus to more basal sliding. The modeled large decrease of effective pressure in the trough

  3. A reassessment of the englacial and subglacial drainage system of Storglaciären in northern Sweden - How much did climate warming change the drainage system? (United States)

    Dahlke, H. E.; Rosqvist, G. N.; Jansson, P.; Lyon, S. W.


    Storglaciären glacier, located in the sub-arctic Tarfala catchment, in northern Sweden is one of the world's longest continuously monitored glaciers which provides a unique research platform for the long-term assessment of climate change impacts on mountain glacier systems. In the presented study we assess signals of climate-induced change in the englacial and subglacial drainage system of the lower ablation area of Storglaciären. Flow velocities and dispersive characteristics of the englacial and subglacial hydraulic system were re-investigated in the 2012 summer melt season using fluorescent dye-tracing tests and compared to previous assessments of from the 1980s and 1990s. Historical hydro-climatic records from Tarfala catchment indicate that there have been significant increases in the cold season air temperature (0.76 °C/decade, 1965-2009) and a doubling of summer event precipitation over the past four decades. These changes contributed to the consistently negative glacier net balance of Storglaciären and significant positive trends in both the mean summer discharge and flood magnitudes over the past 45 years. Six of the eight largest annual maximum flood events occurred during the last decade and meltwater contributions from Storglaciären to the Tarfalajokken stream increased by 15% during the same period. These hydro-climatic trends in conjunction with an isotopic hydrograph separation of present-day samplings indicate that high magnitude rainfall events receive an increasing role in the runoff generation in Tarfala catchment and the glacier systems. This shift towards a greater rainwater contribution to catchment streamflow and glacier runoff indicates fundamental changes in the pathways that water takes through the glacier. The isotopic data suggests that the transit of rainwater via the englacial drainage system is increasing. However, in contrast to the 1980s assessment, dye-tracing tests conducted in 2012 indicate that the majority of meltwater

  4. Modeling of subglacial hydrological development following rapid supraglacial lake drainage (United States)

    Dow, C. F.; Kulessa, B.; Rutt, I. C.; Tsai, V. C.; Pimentel, S.; Doyle, S. H.; van As, D.; Lindbäck, K.; Pettersson, R.; Jones, G. A.; Hubbard, A.


    The rapid drainage of supraglacial lakes injects substantial volumes of water to the bed of the Greenland ice sheet over short timescales. The effect of these water pulses on the development of basal hydrological systems is largely unknown. To address this, we develop a lake drainage model incorporating both (1) a subglacial radial flux element driven by elastic hydraulic jacking and (2) downstream drainage through a linked channelized and distributed system. Here we present the model and examine whether substantial, efficient subglacial channels can form during or following lake drainage events and their effect on the water pressure in the surrounding distributed system. We force the model with field data from a lake drainage site, 70 km from the terminus of Russell Glacier in West Greenland. The model outputs suggest that efficient subglacial channels do not readily form in the vicinity of the lake during rapid drainage and instead water is evacuated primarily by a transient turbulent sheet and the distributed system. Following lake drainage, channels grow but are not large enough to reduce the water pressure in the surrounding distributed system, unless preexisting channels are present throughout the domain. Our results have implications for the analysis of subglacial hydrological systems in regions where rapid lake drainage provides the primary mechanism for surface-to-bed connections.

  5. Test of simultaneous synthetic DNA tracer injections for the estimation of the englacial and subglacial drainage system structure of Storglaciären, northern Sweden (United States)

    Dahlke, H. E.; Leung, S.; Lyon, S. W.; Sharma, A. N.; Walter, M. T.; Williamson, A.


    Storglaciären glacier, located in the sub-arctic Tarfala catchment, in northern Sweden is one of the world's longest continuously monitored glaciers which provides a unique research platform for the long-term assessment of glacier and ice sheet processes. For example, small mountain glacier hydrological knowledge of the subglacial water distribution at the ice-bed interface has been applied to ice sheets to predict basal sliding processes. Basal sliding promoted by hydraulic jacking is an important glacial-velocity control that is dependent on the subglacial flow pathways' morphology. Thus, understanding subglacial water distribution and drainage system structure and morphology is crucial for modeling ice masses' flow. In order to estimate subglacial drainage system structure and morphology dye tracing experiments are widely employed. Tracer experiments provide quantitative parameters for any input location including tracer transit velocity, dispersivity, recovery and storage. However, spatial data coverage is limited by the finite number of tracers available for simultaneous tracing. In the presented study we test the use of synthetic DNA tracers for the assessment of the englacial and subglacial drainage system structure of Storglaciären. The synthetic DNA tracer is composed of polylactic acid (PLA) microspheres into which short strands of synthetic DNA and paramagnetic iron oxide nanoparticles are incorporated (Sharma et al., 2012, Environmental Science & Technology). Because the DNA sequences can be randomly combined the synthetic DNA tracer provides an enormous number of unique tracers (approximately 1.61 x 1060). Thus, these synthetic tracers have the advantage that multiple (>10) experiments can be conducted simultaneously, allowing a greater information gain within a shorter measurement period. Quantities of a certain DNA strand can be detected using biotechnology tools such as polymerase chain reaction (PCR) and quantitative PCR (qPCR). During the 2013

  6. Greenland subglacial drainage evolution regulated by weakly connected regions of the bed. (United States)

    Hoffman, Matthew J; Andrews, Lauren C; Price, Stephen A; Catania, Ginny A; Neumann, Thomas A; Lüthi, Martin P; Gulley, Jason; Ryser, Claudia; Hawley, Robert L; Morriss, Blaine


    Penetration of surface meltwater to the bed of the Greenland Ice Sheet each summer causes an initial increase in ice speed due to elevated basal water pressure, followed by slowdown in late summer that continues into fall and winter. While this seasonal pattern is commonly explained by an evolution of the subglacial drainage system from an inefficient distributed to efficient channelized configuration, mounting evidence indicates that subglacial channels are unable to explain important aspects of hydrodynamic coupling in late summer and fall. Here we use numerical models of subglacial drainage and ice flow to show that limited, gradual leakage of water and lowering of water pressure in weakly connected regions of the bed can explain the dominant features in late and post melt season ice dynamics. These results suggest that a third weakly connected drainage component should be included in the conceptual model of subglacial hydrology.

  7. Subglacial water drainage, storage, and piracy beneath the Greenland ice sheet (United States)

    Lindbäck, K.; Pettersson, R.; Hubbard, A. L.; Doyle, S. H.; As, D.; Mikkelsen, A. B.; Fitzpatrick, A. A.


    Meltwater drainage across the surface of the Greenland ice sheet (GrIS) is well constrained by measurements and modeling, yet despite its critical role, knowledge of its transit through the subglacial environment remains limited. Here we present a subglacial hydrological analysis of a land-terminating sector of the GrIS at unprecedented resolution that predicts the routing of surface-derived meltwater once it has entered the basal drainage system. Our analysis indicates the probable existence of small subglacial lakes that remain undetectable by methods using surface elevation change or radar techniques. Furthermore, the analysis suggests transient behavior with rapid switching of subglacial drainage between competing catchments driven by seasonal changes in the basal water pressure. Our findings provide a cautionary note that should be considered in studies that attempt to relate and infer future response from surface temperature, melt, and runoff from point measurements and/or modeling with measurements of proglacial discharge and ice dynamics.

  8. Predicting subglacial lakes and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets (United States)

    Livingstone, S. J.; Clark, C. D.; Woodward, J.


    In this paper we use the Shreve hydraulic potential equation to predict subglacial lakes and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets. For the Antarctic Ice Sheet we are able to predict known subglacial lakes with a >70% success rate, which demonstrates the validity of this method. Despite the success in predicting known subglacial lakes the calculations produce two-orders of magnitude more lakes than are presently identified, covering 4% of the ice-sheet bed. The difference is thought to result from our poor knowledge of the bed (which has resulted in artefacts associated with the interpolation method), intrinsic errors associated with the simplified modelling approach and because thousands of subglacial lakes, particularly smaller ones, remain to be found. Applying the same modelling approach to the Greenland Ice Sheet predicts only 90 lakes under the present-day ice-sheet configuration, covering 0.2% of the bed. The paucity of subglacial lakes in Greenland is thought to be a function of steeper overall ice-surface gradients. As no lakes have currently been located under Greenland, model predictions will make suitable targets for radar surveys of Greenland to identify subglacial lakes. During deglaciation from the Last Glacial Maximum both ice sheets had more subglacial lakes at their beds, though many of these lakes have persisted to present conditions. These lakes, inherited from past ice-sheet configurations would not form under current surface conditions, suggesting a retreating ice-sheet will have many more subglacial lakes than an advancing ice sheet. This hysteresis effect has implications for ice-stream formation and flow, bed lubrication and meltwater drainage. The lake model also allows modelling of the drainage pathways of the present-day and former Greenland and Antarctic ice sheets. Significantly, key sectors of the ice sheets, such as the Siple Coast (Antarctica) and NE Greenland Ice Stream system, are shown to have

  9. Potential subglacial lake locations and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets (United States)

    Livingstone, S. J.; Clark, C. D.; Woodward, J.; Kingslake, J.


    We use the Shreve hydraulic potential equation as a simplified approach to investigate potential subglacial lake locations and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets. We validate the method by demonstrating its ability to recall the locations of >60% of the known subglacial lakes beneath the Antarctic Ice Sheet. This is despite uncertainty in the ice-sheet bed elevation and our simplified modelling approach. However, we predict many more lakes than are observed. Hence we suggest that thousands of subglacial lakes remain to be found. Applying our technique to the Greenland Ice Sheet, where very few subglacial lakes have so far been observed, recalls 1607 potential lake locations, covering 1.2% of the bed. Our results will therefore provide suitable targets for geophysical surveys aimed at identifying lakes beneath Greenland. We also apply the technique to modelled past ice-sheet configurations and find that during deglaciation both ice sheets likely had more subglacial lakes at their beds. These lakes, inherited from past ice-sheet configurations, would not form under current surface conditions, but are able to persist, suggesting a retreating ice-sheet will have many more subglacial lakes than advancing ones. We also investigate subglacial drainage pathways of the present-day and former Greenland and Antarctic ice sheets. Key sectors of the ice sheets, such as the Siple Coast (Antarctica) and NE Greenland Ice Stream system, are suggested to have been susceptible to subglacial drainage switching. We discuss how our results impact our understanding of meltwater drainage, basal lubrication and ice-stream formation.

  10. Predictive modelling of (palaeo-)subglacial lake locations and their meltwater drainage routeways (United States)

    Livingstone, S. J.; Clark, C.; Tarasoff, L.; Woodward, J.


    There is increasing recognition that subglacial lakes act as key components within the ice sheet system, capable of influencing ice-sheet topography, ice volume and ice flow. At present, much glaciological research is concerned with the role of modern subglacial lake systems in Antarctica. Another approach to the exploration of subglacial lakes involves identification of the geological record of subglacial lakes that once existed beneath ice sheets of the last glaciation. Investigation of such palaeo-subglacial lakes offers significant advantages because we have comprehensive information about the bed properties, they are much more accessible and we can examine and sample the sediments with ease. However, their identification in the geological record remains controversial. We therefore present a simple diagnostic approach based on the Shreve equation, for predicting and investigating likely (palaeo-)subglacial lake locations. Data on the current topography and seafloor bathymetry, and elevation models of the ice and ground surface topography from data-calibrated glaciological modelling are used to calculate the hydraulic potential surface at the ice-sheet bed. Meltwater routing algorithms and the flooding of local hydraulic minima allow us to predict subglacial routeways and lakes respectively. Discovered subglacial lakes beneath the Antarctic Ice Sheet present an opportunity to verify the model using the BEDMAP2 dataset. Using a lake threshold of 5 km2 we identify 12,767 subglacial lakes occurring over 4% of the grounded bed and are able to recover >60% of the discovered subglacial lakes. Applying the same approach to the Greenland Ice Sheet produces 1,607 potential subglacial lakes, covering 1.3% of the bed. These lake localities will make suitable targets for radar surveys attempting to find subglacial lakes. Finally, we apply the Shreve equation to the North American Ice Sheet to try and predict likely palaeo-subglacial lake locations. Given that specific ice

  11. Subglacial hydrological modelling of a rapid lake drainage event on the Russell Glacier catchment, SW Greenland (United States)

    Dow, C. F.; Pimentel, S.; Doyle, S. H.; Booth, A. D.; Fitzpatrick, A.; Jones, G. A.; Kulessa, B.; Hubbard, A.


    We use local-scale subglacial hydrological models to assess the development of the basal drainage system in response to a rapid lake-tapping event on the Russell Glacier catchment, SW Greenland. Water inputs to the model are constrained by in-situ records of the lake drainage rate. Subglacial conditions are estimated from active seismic line analysis including basal topography and substrate characteristics. A borehole slug test model is used to determine the radial flux of water from the drainage input point. Water flowing in the downstream direction is used to drive a 1-D flowband model, which allows development of interacting channelised and distributed drainage systems. The simulated basal water pressures are applied to an elastic beam model to assess vertical uplift at the lake drainage site. Modelled uplift outputs are compared with results from GPS stations located next to the lake. Initial modelling results suggest that channels are necessary for evacuation of water from rapid lake drainage events, even with the presence of a sediment-based bed, the latter of which is usually associated with distributed drainage.

  12. Modelling subglacial drainage and its role in ice-ocean interaction (United States)

    Hewitt, Ian; Dallaston, Michael; Wells, Andrew


    Melting at the ice-ocean interface, both beneath ice shelves and at near-vertical tidewater margins, is strongly influenced by discharge of meltwater from beneath the grounded ice. The fresh water source can help to initiate a buoyant plume that rises up the ice face, entraining heat from the ocean to melt the ice. When the subglacial discharge is spatially and temporally variable, it can cause spatial and temporal variations in the melting rate, which in turn may influence ocean circulation in the cavity and ice flow within the shelf. Recent observations of channelized ice shelf bases may have their origin in variable subglacial discharge from beneath the grounded ice. In this work, we use physically-based models of the subglacial drainage system to examine the likely mode of melt water delivery across the grounding line. We find that if subglacial channels (Rothlisberger channels) exist they can be expected to `trumpet' out as the ocean is approached, due to a lack of confining stress to counteract wall melting. This causes a reduction in horizontal momentum in the water and can lead to pronounced localized melting around channel termini. This may lead to increased propensity for calving at such locations. We also examine the effect of subglacial discharge variations on the evolution of a downstream floating ice shelf. We find that lateral variations in the flow across the grounding line can result in variations in plume-driven melting which evolve to create basal channels in the shelf aligned with the flow. The preferred spacing of the channels is controlled by a balance between buoyancy-driven acceleration and turbulent mixing in the ocean layer.

  13. Photogrammetric recognition of subglacial drainage channels during glacier lake outburst events (United States)

    Schwalbe, Ellen; Koschitzki, Robert


    In recent years, many glaciers all over the world have been distinctly retreating and thinning. One of the consequences of this is the increase of so called glacier lake outburst flood events (GLOFs): Lakes that have been dammed by a glacier spontaneously start to drain through a subglacial channel underneath the glacier due to their outweighing hydrostatic pressure. In a short period of time, the lake water drains under the glacier and causes floods in downstream valleys. In many cases the latter become hazardous for people and their property. Due to glacier movement, the tunnel will soon collapse, and the glacier lake refills, thus starting a new GLOF cycle. The mechanisms ruling GLOF events are yet still not fully understood by glaciologists. Thus, there is a demand for data and measurement values that can help to understand and model the phenomena. In view of the above, we will show how photogrammetric image sequence analysis can be used to collect data which allows for drawing conclusions about the location and development of a subglacial channel. The work is a follow-up on earlier work on a photogrammetric GLOF early warning system (Mulsow et. al., 2013). For the purpose of detecting the subglacial tunnel, a camera has been installed in a pilot study to observe the area of the Colonia glacier (Northern Patagonian ice field) where it dams the lake Lago Cachet II. To verify the hypothesis, that the course of the subglacial tunnel is indicated by irregular surface motion patterns during its collapse, the camera acquired image sequences of the glacier surface during several GLOF events. Applying LSM-based tracking techniques to these image sequences, surface feature motion trajectories could be obtained for a dense raster of glacier points. Since only a single camera has been used for image sequence acquisition, depth information is required to scale the trajectories. Thus, for scaling and georeferencing of the measurements a GPS-supported photogrammetric network

  14. Direct observations of evolving subglacial drainage beneath the Greenland Ice Sheet. (United States)

    Andrews, Lauren C; Catania, Ginny A; Hoffman, Matthew J; Gulley, Jason D; Lüthi, Martin P; Ryser, Claudia; Hawley, Robert L; Neumann, Thomas A


    Seasonal acceleration of the Greenland Ice Sheet is influenced by the dynamic response of the subglacial hydrologic system to variability in meltwater delivery to the bed via crevasses and moulins (vertical conduits connecting supraglacial water to the bed of the ice sheet). As the melt season progresses, the subglacial hydrologic system drains supraglacial meltwater more efficiently, decreasing basal water pressure and moderating the ice velocity response to surface melting. However, limited direct observations of subglacial water pressure mean that the spatiotemporal evolution of the subglacial hydrologic system remains poorly understood. Here we show that ice velocity is well correlated with moulin hydraulic head but is out of phase with that of nearby (0.3-2 kilometres away) boreholes, indicating that moulins connect to an efficient, channelized component of the subglacial hydrologic system, which exerts the primary control on diurnal and multi-day changes in ice velocity. Our simultaneous measurements of moulin and borehole hydraulic head and ice velocity in the Paakitsoq region of western Greenland show that decreasing trends in ice velocity during the latter part of the melt season cannot be explained by changes in the ability of moulin-connected channels to convey supraglacial melt. Instead, these observations suggest that decreasing late-season ice velocity may be caused by changes in connectivity in unchannelized regions of the subglacial hydrologic system. Understanding this spatiotemporal variability in subglacial pressures is increasingly important because melt-season dynamics affect ice velocity beyond the conclusion of the melt season.

  15. Geomorphological evidence of channelized subglacial meltwater drainage under the Scandinavian Ice Sheet (United States)

    Adamczyk, Aleksander; Wysota, Wojciech; Sobiech, Marcin; Piotrowski, Jan A.


    The impact of subglacial meltwater erosion on shaping glacial landscapes is contentious and often difficult to constrain due to the lack of unequivocal diagnostic criteria. The same holds for the role of subglacial meltwater in glacier movement processes and sediment transport and deposition. Here we present new evidence of widespread channelized erosion under the southern, soft-bedded fringe of the last Scandinavian Ice Sheet (SIS) based on high-resolution terrain analysis with LiDAR imagery. We identify several tens of sites with "glacial curvilineation" landscapes first recognized by Lesemann et al. (2010, 2014) and considered as evidence of erosion by turbulent meltwater flows at the ice/bed interface. The "glacial curvilineation" landscapes mapped here consist of sets of parallel, winding ridges typically several metres high and up to several kilometres long occupying glacial overdeepenings and tunnel valleys. The ridges are aligned approximately perpendicular to the past ice sheet margins and they are composed of various deposits often pre-dating the last ice advance. We interpret them as erosional remnants of older landscapes dissected by high-energy subglacial meltwater flows. These findings suggest that the palaeoglaciological significance of meltwater drainage under the southern portion of SIS may have been grossly underestimated. References Lesemann, J.-E., Piotrowski, J.A. and Wysota, W., 2010. „Glacial curvilineations": New glacial landforms produced by longitudinal vortices in subglacial meltwater flows. Geomorphology 120, 153-161. Lesemann, J.-E., Piotrowski, J.A. and Wysota, W., 2014. Genesis of the "glacial curvilineation" landscape by meltwater processes under the former Scandinavian Ice Sheet, Poland. Sedimentary Geology 312, 1-18.

  16. Melt-induced speed-up of Greenland ice sheet offset by efficient subglacial drainage. (United States)

    Sundal, Aud Venke; Shepherd, Andrew; Nienow, Peter; Hanna, Edward; Palmer, Steven; Huybrechts, Philippe


    Fluctuations in surface melting are known to affect the speed of glaciers and ice sheets, but their impact on the Greenland ice sheet in a warming climate remains uncertain. Although some studies suggest that greater melting produces greater ice-sheet acceleration, others have identified a long-term decrease in Greenland's flow despite increased melting. Here we use satellite observations of ice motion recorded in a land-terminating sector of southwest Greenland to investigate the manner in which ice flow develops during years of markedly different melting. Although peak rates of ice speed-up are positively correlated with the degree of melting, mean summer flow rates are not, because glacier slowdown occurs, on average, when a critical run-off threshold of about 1.4 centimetres a day is exceeded. In contrast to the first half of summer, when flow is similar in all years, speed-up during the latter half is 62 ± 16 per cent less in warmer years. Consequently, in warmer years, the period of fast ice flow is three times shorter and, overall, summer ice flow is slower. This behaviour is at odds with that expected from basal lubrication alone. Instead, it mirrors that of mountain glaciers, where melt-induced acceleration of flow ceases during years of high melting once subglacial drainage becomes efficient. A model of ice-sheet flow that captures switching between cavity and channel drainage modes is consistent with the run-off threshold, fast-flow periods, and later-summer speeds we have observed. Simulations of the Greenland ice-sheet flow under climate warming scenarios should account for the dynamic evolution of subglacial drainage; a simple model of basal lubrication alone misses key aspects of the ice sheet's response to climate warming.

  17. Tracking seasonal subglacial drainage evolution of alpine glaciers using radiogenic Nd and Sr isotope systematics: Lemon Creek Glacier, Alaska (United States)

    Clinger, A. E.; Aciego, S.; Stevenson, E. I.; Arendt, C. A.


    The transport pathways of water beneath a glacier are subject to change as melt seasons progress due to variability in the balance between basal water pressure and water flux. Subglacial hydrology has been well studied, but the understanding of spatial distribution is less well constrained. Whereas radiogenic isotopic tracers have been traditionally used as proxies to track spatial variability and weathering rates in fluvial and riverine systems, these techniques have yet to be applied extensively to the subglacial environment and may help resolve ambiguity in subglacial hydrology. Research has shown the 143Nd/144Nd values can reflect variation in source provenance processes due to variations in the age of the continental crust. Correlating the 143Nd/144Nd with other radiogenic isotope systematics such as strontium (87Sr/86Sr) provides important constraints on the role of congruent and incongruent weathering processes. Our study presents the application of Nd and Sr systematics using isotopic ratios to the suspended load of subglacial meltwater collected over a single melt season at Lemon Creek Glacier, USA (LCG). The time-series data show an average ɛNd ~ -6.83, indicating a young bedrock (~60 MYA). Isotopic variation helps track the seasonal expansion of the subglacial meltwater channels and subsequent return to early season conditions due to the parabolic trend towards less radiogenic Nd in June and towards more radiogenic Nd beginning in mid-August. However, the high variability in July and early August may reflect a mixture of source as the channels diverge and derive sediment from differently aged lithologies. We find a poor correlation between 143Nd/144Nd and 87Sr/86Sr (R2= 0.38) along with a slight trend towards more radiogenic 87Sr/86Sr values with time ((R2= 0.49). This may indicate that, even as the residence time decreases over the melt season, the LCG subglacial system is relatively stable and that the bedrock is congruently weathered. Our study

  18. Sustainable Drainage Systems


    Miklas Scholz


    Urban water management has somewhat changed since the publication of The Sustainable Drainage System (SuDS) Manual in 2007 [1], transforming from building traditional sewers to implementing SuDS, which are part of the best management practice techniques used in the USA and seen as contributing to water-sensitive urban design in Australia. Most SuDS, such as infiltration trenches, swales, green roofs, ponds, and wetlands, address water quality and quantity challenges, and enhance the local bio...

  19. Calculating the balance between atmospheric CO2 drawdown and organic carbon oxidation in subglacial hydrochemical systems (United States)

    Graly, Joseph A.; Drever, James I.; Humphrey, Neil F.


    In order to constrain CO2 fluxes from biogeochemical processes in subglacial environments, we model the evolution of pH and alkalinity over a range of subglacial weathering conditions. We show that subglacial waters reach or exceed atmospheric pCO2 levels when atmospheric gases are able to partially access the subglacial environment. Subsequently, closed system oxidation of sulfides is capable of producing pCO2 levels well in excess of atmosphere levels without any input from the decay of organic matter. We compared this model to published pH and alkalinity measurements from 21 glaciers and ice sheets. Most subglacial waters are near atmospheric pCO2 values. The assumption of an initial period of open system weathering requires substantial organic carbon oxidation in only 4 of the 21 analyzed ice bodies. If the subglacial environment is assumed to be closed from any input of atmospheric gas, large organic carbon inputs are required in nearly all cases. These closed system assumptions imply that order of 10 g m-2 y-1 of organic carbon are removed from a typical subglacial environment—a rate too high to represent soil carbon built up over previous interglacial periods and far in excess of fluxes of surface deposited organic carbon. Partial open system input of atmospheric gases is therefore likely in most subglacial environments. The decay of organic carbon is still important to subglacial inorganic chemistry where substantial reserves of ancient organic carbon are found in bedrock. In glaciers and ice sheets on silicate bedrock, substantial long-term drawdown of atmospheric CO2 occurs.

  20. Sustainable Drainage Systems

    Directory of Open Access Journals (Sweden)

    Miklas Scholz


    Full Text Available Urban water management has somewhat changed since the publication of The Sustainable Drainage System (SuDS Manual in 2007 [1], transforming from building traditional sewers to implementing SuDS, which are part of the best management practice techniques used in the USA and seen as contributing to water-sensitive urban design in Australia. Most SuDS, such as infiltration trenches, swales, green roofs, ponds, and wetlands, address water quality and quantity challenges, and enhance the local biodiversity while also being acceptable aesthetically to the public. Barriers to the implementation of SuDS include adoption problems, flood and diffuse pollution control challenges, negative public perception, and a lack of decision support tools addressing, particularly, the retrofitting of these systems while enhancing ecosystem services. [...

  1. Anatomy of a meltwater drainage system beneath the ancestral East Antarctic ice sheet (United States)

    Simkins, Lauren M.; Anderson, John B.; Greenwood, Sarah L.; Gonnermann, Helge M.; Prothro, Lindsay O.; Halberstadt, Anna Ruth W.; Stearns, Leigh A.; Pollard, David; Deconto, Robert M.


    Subglacial hydrology is critical to understand the behaviour of ice sheets, yet active meltwater drainage beneath contemporary ice sheets is rarely accessible to direct observation. Using geophysical and sedimentological data from the deglaciated western Ross Sea, we identify a palaeo-subglacial hydrological system active beneath an area formerly covered by the East Antarctic ice sheet. A long channel network repeatedly delivered meltwater to an ice stream grounding line and was a persistent pathway for episodic meltwater drainage events. Embayments within grounding-line landforms coincide with the location of subglacial channels, marking reduced sedimentation and restricted landform growth. Consequently, channelized drainage at the grounding line influenced the degree to which these landforms could provide stability feedbacks to the ice stream. The channel network was connected to upstream subglacial lakes in an area of geologically recent rifting and volcanism, where elevated heat flux would have produced sufficient basal melting to fill the lakes over decades to several centuries; this timescale is consistent with our estimates of the frequency of drainage events at the retreating grounding line. Based on these data, we hypothesize that ice stream dynamics in this region were sensitive to the underlying hydrological system.

  2. Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard, investigated by ground penetrating radar

    Directory of Open Access Journals (Sweden)

    K. Bælum


    Full Text Available Proglacial icings accumulate in front of many High Arctic glaciers during the winter months, as water escapes from englacial or subglacial storage. Such icings have been interpreted as evidence for warm-based subglacial conditions, but several are now known to occur in front of cold-based glaciers. In this study, we investigate the drainage system of Tellbreen, a 3.5 km long glacier in central Spitsbergen, where a large proglacial icing develops each winter, to determine the location and geometry of storage elements. Digital elevation models (DEMs of the glacier surface and bed were constructed using maps, differential GPS and ground penetrating radar (GPR. Rates of surface lowering indicate that the glacier has a long-term mass balance of −0.6 ± 0.2 m/year. Englacial and subglacial drainage channels were mapped using GPR, showing that Tellbreen has a diverse drainage system that is capable of storing, transporting and releasing water year round. In the upper part of the glacier, drainage is mainly via supraglacial channels. These transition downglacier into shallow englacial "cut and closure" channels, formed by the incision and roof closure of supraglacial channels. Below thin ice near the terminus, these channels reach the bed and contain stored water throughout the winter months. Even though no signs of temperate ice were detected and the bed is below pressure-melting point, Tellbreen has a surface-fed, channelized subglacial drainage system, which allows significant storage and delayed discharge.

  3. Technical note on drainage systems

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby

    This technical note will present simple but widely used methods for the design of drainage systems. The note will primarily deal with surface water (rainwater) which on a satisfactorily way should be transport into the drainage system. Traditional two types of sewer systems exist: A combined system......’s not major different than described below - just remember to include this contribution for combined systems where the surface water (rain) and sewage are carried in the same pipes in the system and change some of the parameters for failure allowance (this will be elaborated further later on). The technical...

  4. 24 CFR 3280.610 - Drainage systems. (United States)


    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Drainage systems. 3280.610 Section... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Plumbing Systems § 3280.610 Drainage systems. (a) General. (1) Each fixture directly connected to the drainage system shall be installed with a...

  5. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities (United States)

    How, Penelope; Benn, Douglas I.; Hulton, Nicholas R. J.; Hubbard, Bryn; Luckman, Adrian; Sevestre, Heïdi; van Pelt, Ward J. J.; Lindbäck, Katrin; Kohler, Jack; Boot, Wim


    Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  6. Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

    Directory of Open Access Journals (Sweden)

    P. How


    Full Text Available Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

  7. 24 CFR 3285.604 - Drainage system. (United States)


    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Drainage system. 3285.604 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Ductwork and Plumbing and Fuel Supply Systems § 3285.604 Drainage system. (a) Crossovers. Multi-section homes with plumbing in more than one section...

  8. Subglacial lake and meltwater flow predictions of the last North American and European Ice Sheets (United States)

    Livingstone, S. J.; Clark, C. D.; Tarasov, L.


    There is increasing recognition that subglacial lakes act as key components within the ice sheet system, capable of influencing ice-sheet topography, ice volume and ice flow. The subglacial water systems themselves are recognised as being both active and dynamic, with large discharges of meltwater capable of flowing down hydrological pathways both between lakes and to the ice-sheet margins. At present, much glaciological research is concerned with the role of modern subglacial lake systems in Antarctica. Another approach to the exploration of subglacial lakes involves identification of the geological record of subglacial lakes that once existed beneath ice sheets of the last glaciation. Investigation of such palaeo-subglacial lakes offers significant advantages because we have comprehensive information about the bed properties, they are much more accessible and we can examine and sample the sediments with ease. If we can find palaeo-subglacial lakes then we have the potential to advance understanding with regard to the topographic context and hydrological pathways that the phenomena form a part of; essentially we gain spatial and sedimentological information in relation to investigations of contemporary subglacial lakes and lose out on the short-time dynamics. In this work we present predictions of palaeo-subglacial lakes and meltwater drainage pathways under the former European and North American ice sheets during the last glaciation. We utilise data on the current topography and seafloor bathymetry, and elevation models of the ice and ground surface topography (interpolated to a 5 km grid) to calculate the hydraulic potential surface at the ice-sheet bed. Meltwater routing algorithms and the flooding of local hydraulic minima allow us to predict subglacial channels and lakes respectively. Given that specific ice-surface and bed topographies are only known from modelled outputs, and thus contain significant uncertainty, we utilise many such outputs to examine

  9. Drainage information analysis and mapping system. (United States)


    The primary objective of this research is to develop a Drainage Information Analysis and Mapping System (DIAMS), with online inspection : data submission, which will comply with the necessary requirements, mandated by both the Governmental Accounting...

  10. Reconstruction of a Palaeo-Subglacial Lake Network in Alberta, Canada (United States)

    Livingstone, S. J.; Utting, D.; Clark, C.; Ruffell, A.; Pawley, S. M.; Atkinson, N.; Mallon, G.


    Subglacial lakes have been widely documented since first being identified beneath the Antarctic Ice Sheet in the 1960s and comprise a significant component of the subglacial hydrological system (Wright & Siegert, 2011). However, their investigation is largely limited to contemporary ice masses despite critical information that could be gleaned from palaeo-subglacial lake studies, including: (i) their influence on meltwater drainage, ice flow and ice streams; (ii) details about how they relate to palaeo-floods, ice dynamics and sub-Milankovitch-scale climate events; and (iii) as archives of long-term Quaternary climate change. They are also readily available, we can sample the sediments and maps the landforms with ease and we have comprehensive information on the lake-bed properties. Output from numerical ice sheet models and the simple Shreve equation approach has been used to diagnose where subglacial lakes are likely to have occurred in the geological record (Livingstone et al. 2013). However, their identification remains controversial due to the difficulty in distinguishing their signature from proglacial lake deposits (see Livingstone et al. 2012). Here, we present new geomorphological, geophysical and sedimentological evidence for the existence of a palaeo-subglacial lake network beneath the suture zone of the former Cordilleran and Laurentide ice sheets. These relatively small (~1 km diameter) palaeo-subglacial lakes manifest as flat-spots in a drumlin field and are perched in upland areas behind small ridges. The flat-spots, which comprise basins in-filled with diamicton, are associated with subglacial meltwater channels and eskers that we interpret to document lake drainage events. References: Livingstone, S.J., et al., 2012. Quaternary Science Reviews,55, 88-110. Livingstone, S.J., et al., 2013. Earth and Planetary Science Letters, 375, 13-33. Wright A.P., Siegert M.J. 2011. In: Siegert, M.J., Kennicutt, C., Bindschadler, B. (Eds.). Subglacial Antarctic

  11. Systemic venous drainage: can we help Newton? (United States)

    Corno, Antonio F


    In recent years substantial progress occurred in the techniques of cardiopulmonary bypass, but the factor potentially limiting the flexibility of cardiopulmonary bypass remains the drainage of the systemic venous return. In the daily clinical practice of cardiac surgery, the amount of systemic venous return on cardiopulmonary bypass is directly correlated with the amount of the pump flow. As a consequence, the pump flow is limited by the amount of venous return that the pump is receiving. On cardiopulmonary bypass the amount of venous drainage depends upon the central venous pressure, the height differential between patient and inlet of the venous line into the venous reservoir, and the resistance in the venous cannula(s) and circuit. The factors determining the venous return to be taken into consideration in cardiac surgery are the following: (a) characteristics of the individual patient; (b) type of planned surgical procedure; (c) type of venous cannula(s); (d) type of circuit for cardiopulmonary bypass; (e) strategy of cardiopulmonary bypass; (f) use of accessory mechanical systems to increased the systemic venous return. The careful pre-operative evaluation of all the elements affecting the systemic venous drainage, including the characteristics of the individual patient and the type of required surgical procedure, the choice of the best strategy of cardiopulmonary bypass, and the use of the most advanced materials and tools, can provide a systemic venous drainage substantially better than what it would be allowed by the simple "Law of universal gravitation" by Isaac Newton.

  12. Optimizing the closed suction surgical drainage system. (United States)

    Carruthers, Katherine H; Eisemann, Bradley S; Lamp, Susan; Kocak, Ergun


    Closed suction drains are indicated in a wide array of postoperative settings, with many distinct drainage systems available to the surgeon. The purpose of this study was to compare the suction gradients achieved using 2 different sizes of suction reservoirs and 2 different techniques for generating negative pressure. Drainage reservoirs of 100 and 400 ml were chosen to evaluate their ability to achieve suction. Suction was established in both sizes of drains by pressing the sides of the reservoir together or by pushing the bottom of the reservoir toward the top. Negative pressures were recorded with the reservoir empty, and after every 10-ml addition of saline. Averages were graphed to illustrate the applied suction over a range of drain volumes. The 100-ml drainage system reached a peak suction of -117.6 mmHg, while the 400-ml drainage system reached only a peak suction of -71.4 mmHg. Both of the maximum suction readings were achieved using the full-squeeze technique. The bottom-pushed-in technique did not result in any sustained measurable levels of suction using either of the reservoir volumes. Smaller drain reservoirs are more successful in generating a high initial suction than larger reservoirs, especially when the volume of fluid in the drain is relatively low. In all sizes of drains, compressing the sides of the reservoir is a far better technique for establishing negative pressure than pressing the bottom of the drain up toward the top.

  13. Antarctic subglacial lakes drain through sediment-floored canals: theory and model testing on real and idealized domains (United States)

    Carter, Sasha P.; Fricker, Helen A.; Siegfried, Matthew R.


    Over the past decade, satellite observations of ice surface height have revealed that active subglacial lake systems are widespread under the Antarctic Ice Sheet, including the ice streams. For some of these systems, additional observations of ice-stream motion have shown that lake activity can affect ice-stream dynamics. Despite all this new information, we still have insufficient understanding of the lake-drainage process to incorporate it into ice-sheet models. Process models for drainage of ice-dammed lakes based on conventional R-channels incised into the base of the ice through melting are unable to reproduce the timing and magnitude of drainage from Antarctic subglacial lakes estimated from satellite altimetry given the low hydraulic gradients along which such lakes drain. We have developed an alternative process model, in which channels are mechanically eroded into the underlying deformable subglacial sediment. When applied to the known active lakes of the Whillans-Mercer ice-stream system, the model successfully reproduced both the inferred magnitudes and recurrence intervals of lake-volume changes, derived from Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data for the period 2003-2009. Water pressures in our model changed as the flood evolved: during drainage, water pressures initially increased as water flowed out of the lake primarily via a distributed system, then decreased as the channelized system grew, establishing a pressure gradient that drew water away from the distributed system. This evolution of the drainage system can result in the observed internal variability of ice flow over time. If we are correct that active subglacial lakes drain through canals in the sediment, this mechanism also implies that active lakes are typically located in regions underlain by thick subglacial sediment, which may explain why they are not readily observed using radio-echo-sounding techniques.

  14. Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line (United States)

    Drews, R.; Pattyn, F.; Hewitt, I. J.; Ng, F. S. L.; Berger, S.; Matsuoka, K.; Helm, V.; Bergeot, N.; Favier, L.; Neckel, N.


    Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers' size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

  15. Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line. (United States)

    Drews, R; Pattyn, F; Hewitt, I J; Ng, F S L; Berger, S; Matsuoka, K; Helm, V; Bergeot, N; Favier, L; Neckel, N


    Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers' size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

  16. A subglacial meltwater channel system in Marguerite Bay: observations from sediment cores, an underwater ROV and ship-mounted instruments (United States)

    Hogan, Kelly; Dowdeswell, Julian; Bartholomew, Ian; Noormets, Riko; Evans, Jeffrey; Cofaigh, Colm Ó.


    On the western Antarctic Peninsula grounded ice is known to have advanced through Marguerite Bay to a position at the shelf edge during the last glacial. Multibeam bathymetry from Marguerite Trough have revealed streamlined subglacial bedforms along the length of the trough and meltwater features (subglacial basins and channels) in the bay and on the inner to middle continental shelf. The channels are inferred to be subglacial in origin based on the fact that they have sections with negative slope gradients and areas of overdeepening along their thalwegs. We investigate the subglacial channel systems on the continental shelf in several ways. First, we investigate channel origin by analysing a series of sediment cores acquired in the channels and in the flat areas immediately in front of them. Interestingly, the cores record a relatively "normal" Late Pleistocene glacial-postglacial stratigraphy of (glacial) diamicts overlain by (post-glacial) hemipelagic muds and do not sample any waterlain sediments (bedded sands, gravels). Physical parameters from the cores allow us to correlate these facies with sediment cores further out on the continental shelf (cf. Kilfeather et al., 2011) suggesting that ice was grounded in the channel system during the last glacial. Secondly, we investigate channel morphometry using high-resolution multibeam data (gridded surfaces have cell sizes c. 0.4 m) and the medium-resolution multibeam data (grid cell sizes of c. 40 m) from ship-mounted systems; the data are complimented by seafloor photographs taken by the Isis ROV. Integration of the these data reveals that the side slopes of the channels are much steeper than originally thought, with some even being undercut, which will affect estimates of potential meltwater flux through the channel system. Given the incredibly large meltwater fluxes that would be required for continuous flow through the channel system, and the evidence for grounded ice during the last glacial, we consider it

  17. Floating roof tank drainage system improvements

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, Wagner Andrade da; Holdack, Ricardo; Ruza, Adilson; Schraml, Karina Chacur; Fujikawa, Mauro Yutaka [Petrobras Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Silva, Adilson Batista da [ATP Engenharia Ltda., Parnamirim, RN (Brazil)


    TRANSPETRO's tank TQ-8803 is a floating roof tank, used for storing gasoline at atmospheric pressure. This tank presented a roof movement restriction at a certain height in the receiving and sending operations, besides problems in draining the rainwater from the floating roof. The roof drain was a central articulated pipe, with a single intake spot. The tank had an anti-rotational 12-inch guide tube and a separate 8-inch gauging tube. It was verified that there were signs of friction between the tubes and their nozzles, and that both the tubes were out of plummet. The solution was removing both the tubes and installing a single anti-rotational guide tube, which received the level and temperature gauges, besides being used for manual gauging and as sampling nozzle. A new drainage system was also projected. It uses a flexible tube, supported in a spiral form on the bottom of the tank, and has a main and four auxiliary drainage boxes, positioned in the center of the roof and next to the pontoon, below the mobile stairs. These boxes were provided with elastomer duckbill check valves, substituting the swing check valves previously installed. After the maintenance conclusion, the anomalies found before were solved. (author)

  18. Materials for subsurface land drainage systems

    NARCIS (Netherlands)

    Stuyt, L.C.P.M.; Dierickx, W.; Martínez Beltrán, J.


    The purpose of this Paper is to provide this practical information to drainage engineers and contractors. The Paper is based on the current knowledge of water flow into drain pipes and envelopes, their properties and applicability. It also contains guidelines for the selection of drainage materials

  19. Subglacial discharge at tidewater glaciers revealed by seismic tremor (United States)

    Bartholomaus, Timothy C.; Amundson, Jason M.; Walter, Jacob I.; O'Neel, Shad; West, Michael E.; Larsen, Christopher F.


    Subglacial discharge influences glacier basal motion and erodes and redeposits sediment. At tidewater glacier termini, discharge drives submarine terminus melting, affects fjord circulation, and is a central component of proglacial marine ecosystems. However, our present inability to track subglacial discharge and its variability significantly hinders our understanding of these processes. Here we report observations of hourly to seasonal variations in 1.5–10 Hz seismic tremor that strongly correlate with subglacial discharge but not with basal motion, weather, or discrete icequakes. Our data demonstrate that vigorous discharge occurs from tidewater glaciers during summer, in spite of fast basal motion that could limit the formation of subglacial conduits, and then abates during winter. Furthermore, tremor observations and a melt model demonstrate that drainage efficiency of tidewater glaciers evolves seasonally. Glaciohydraulic tremor provides a means by which to quantify subglacial discharge variations and offers a promising window into otherwise obscured glacierized environments.

  20. Examples of Models Fit to Magnetic Anomalies Observed Over Subaerial, Submarine, and Subglacial Volcanoes in the West Antarctic Rift System (United States)

    Behrendt, J. C.; Finn, C. A.; Blankenship, D. D.


    Aeromagnetic and marine magnetic surveys over the volcanically active West Antarctic rift system, constrained by seismic reflection profiles over the Ross Sea continual shelf, and radar ice sounding surveys over the West Antarctic Ice Sheet (WAIS) allowed calculation of models fit to very high-amplitude anomalies. We present several examples: exposed 2700-m high, subaerial erupted volcano Mt Melbourne; the 750-m high source of anomaly D (Hamilton submarine volcano) in the Ross sea; and the 600-m high edifice of Mt. CASERTZ beneath the WAIS. The character of these anomalies and their sources varies greatly, and is inferred to be the result of subaerial, submarine and subglacial emplacement respectively. Mt. Melbourne erupted through the WAIS at a time when it was grounded over the Ross Sea continental shelf. Highly magnetic volcanic flows inferred to have high remanent (normal) magnetization in the present field direction produce the 600-nT positive anomaly. The flows protected the edifice above the ice from erosion. Negligible amounts of probably subglacially erupted, apparently non-magnetic hyaloclastite exist in association with Mt. Melbourne. Mt. CASERTZ is nonmagnetic and the edifice is interpreted as consisting of a transient mound of unconsolidated hyaloclastite injected into the WAIS. However Mt. CASERTZ, about 8-km diameter, overlies a 200-m high, 40-km wide highly magnetic residual edifice modeled as the top of the source (an active subglacial volcano) of a 400-nT high positive anomaly. Any former edifices comprising hyaloclastite, pillow breccia or other volcanic debris injected into the moving WAIS apparently have been removed. About 400 other high- amplitude anomalies associated with low relief (80 percent less than 200 m) edifices at the base of the ice (the tops of the sources of these steep gradient anomalies) beneath the WAIS defined by radar ice sounding have been interpreted as having former hyaloclastite edifices, which were removed by the moving

  1. Exploration of Subglacial Lake Ellsworth (United States)

    Ross, N.


    Antarctic subglacial lakes are thought to be extreme habitats for microbial life and may contain important records of ice sheet history within their lake-floor sediments. To find if this is true, and to answer the science questions that would follow, direct measurement and sampling of these environments is required. Ever since the water depth of Vostok Subglacial Lake in East Antarctica was shown to be >500 m, attention has been given to how these unique, ancient and pristine subglacial environments may be entered without contamination and adverse disturbance. Several organizations have offered guidelines on the desirable cleanliness and sterility requirements for direct sampling experiments, including the US National Academy of Sciences and the Scientific Committee on Antarctic Research. The aims, design and implementation of subglacial lake access experiments have direct relevance for the exploration of extra-terrestrial ice-covered bodies (e.g. Europa) and the search for microbial life elsewhere in the Solar System. This presentation summarizes the scientific protocols and methods being developed for the exploration of Ellsworth Subglacial Lake in West Antarctica, and provides an up-to-date summary of the status of the project. The proposed exploration, planned for December 2012, involves accessing the lake using a hot-water drill and deploying a sampling probe and sediment corer to allow in situ measurement and sample collection. Details are presented on how this can be undertaken with minimal environmental impact that maximizes scientific return without compromising the environment for future experiments. The implications of this experiment for the search for extra-terrestrial life will be discussed.

  2. Structure and evolution of the drainage system of a Himalayan debris-covered glacier, and its relationship with patterns of mass loss (United States)

    Benn, Douglas I.; Thompson, Sarah; Gulley, Jason; Mertes, Jordan; Luckman, Adrian; Nicholson, Lindsey


    We provide the first synoptic view of the drainage system of a Himalayan debris-covered glacier and its evolution through time, based on speleological exploration and satellite image analysis of Ngozumpa Glacier, Nepal. The drainage system has several linked components: (1) a seasonal subglacial drainage system below the upper ablation zone; (2) supraglacial channels, allowing efficient meltwater transport across parts of the upper ablation zone; (3) sub-marginal channels, allowing long-distance transport of meltwater; (4) perched ponds, which intermittently store meltwater prior to evacuation via the englacial drainage system; (5) englacial cut-and-closure conduits, which may undergo repeated cycles of abandonment and reactivation; and (6) a "base-level" lake system (Spillway Lake) dammed behind the terminal moraine. The distribution and relative importance of these elements has evolved through time, in response to sustained negative mass balance. The area occupied by perched ponds has expanded upglacier at the expense of supraglacial channels, and Spillway Lake has grown as more of the glacier surface ablates to base level. Subsurface processes play a governing role in creating, maintaining, and shutting down exposures of ice at the glacier surface, with a major impact on spatial patterns and rates of surface mass loss. Comparison of our results with observations on other glaciers indicate that englacial drainage systems play a key role in the response of debris-covered glaciers to sustained periods of negative mass balance.

  3. Evaluation of Life Cycle Assessment (LCA) for Roadway Drainage Systems. (United States)

    Byrne, Diana M; Grabowski, Marta K; Benitez, Amy C B; Schmidt, Arthur R; Guest, Jeremy S


    Roadway drainage design has traditionally focused on cost-effectively managing water quantity; however, runoff carries pollutants, posing risks to the local environment and public health. Additionally, construction and maintenance incur costs and contribute to global environmental impacts. While life cycle assessment (LCA) can potentially capture local and global environmental impacts of roadway drainage and other stormwater systems, LCA methodology must be evaluated because stormwater systems differ from wastewater and drinking water systems to which LCA is more frequently applied. To this end, this research developed a comprehensive model linking roadway drainage design parameters to LCA and life cycle costing (LCC) under uncertainty. This framework was applied to 10 highway drainage projects to evaluate LCA methodological choices by characterizing environmental and economic impacts of drainage projects and individual components (basin, bioswale, culvert, grass swale, storm sewer, and pipe underdrain). The relative impacts of drainage components varied based on functional unit choice. LCA inventory cutoff criteria evaluation showed the potential for cost-based criteria, which performed better than mass-based criteria. Finally, the local aquatic benefits of grass swales and bioswales offset global environmental impacts for four impact categories, highlighting the need to explicitly consider local impacts (i.e., direct emissions) when evaluating drainage technologies.

  4. Ross Ice Drainage System (RIDS) Glaciochemical Analysis, Version 1 (United States)

    National Aeronautics and Space Administration — The Ross Ice Drainage System (RIDS) project provides a high-resolution record of atmospheric chemical deposition taken from several ice cores and snow pits located...

  5. Subglacial hydrology of the lake district ice lobe during the Younger Dryas (ca. 12 500 - 11 600 years ago) in the Kylaeniemi area, SE Finland

    Energy Technology Data Exchange (ETDEWEB)

    Lunkka, J. P.; Moisio, K.; Vainio, A. [Univ. of Oulu (Finland)


    It is essential to gain knowledge on the subglacial hydrological conditions at the glacier bed / bedrock interface when assessing how bedrock fracture zones affect subglacial melt water flow and in which subglacial zones pressurized and oxygen-rich melt water penetrates into the bedrock fracture systems. In the warm-based glacier zones, a part of subglacial melt water will penetrate deep into the fracture systems although the major part of melt water is drained to and beyond the ice margin via subglacial tunnel networks especially in the areas where ice is flowing on the crystalline bedrock. During the last deglaciation phase of the former Scandinavian Ice Sheet, glaciofluvial accumulations were deposited and these sediment accumulations are highly important when picturing the subglacial hydrology of different ice streams during deglaciation in the crystalline bedrock area. The aim of the present work was to map the bedrock fracture zones in the Kylaeniemi area and to shed light on the subglacial hydrology of the Scandinavian Ice Sheet's Lake District Ice Stream that occupied the Kylaeniemi area during the Younger Dryas between ca. 12 500 - 11 600 years ago. The special emphasis within this general aim was to study the relationship between bedrock fracture zones and the routes of subglacial drainage paths. The methods used to map and study bedrock fracture zones and subglacial drainage paths included remotes sensing methods, field observations, ground penetrating radar (GPR) investigations and GIS-based reconstructions. Conventional geological field methods aided by the GPR-method were also used to map bedrock exposures and their structures and to define the type of glaciofluvial sediments and glaciofluvial landform associations. Two main fracture zone sets occur in the study area. The most prominent bedrock fracture zone set trends NW-SE while the other, less prominent fracture zone set is aligned in NE-SW direction. The majority of the minor joint sets in

  6. Adequate drainage system design for heap leaching structures. (United States)

    Majdi, Abbas; Amini, Mehdi; Nasab, Saeed Karimi


    The paper describes an optimum design of a drainage system for a heap leaching structure which has positive impacts on both mine environment and mine economics. In order to properly design a drainage system the causes of an increase in the acid level of the heap which in turn produces severe problems in the hydrometallurgy processes must be evaluated. One of the most significant negative impacts induced by an increase in the acid level within a heap structure is the increase of pore acid pressure which in turn increases the potential of a heap-slide that may endanger the mine environment. In this paper, initially the thickness of gravelly drainage layer is determined via existing empirical equations. Then by assuming that the calculated thickness is constant throughout the heap structure, an approach has been proposed to calculate the required internal diameter of the slotted polyethylene pipes which are used for auxiliary drainage purposes. In order to adequately design this diameter, the pipe's cross-sectional deformation due to stepped heap structure overburden pressure is taken into account. Finally, a design of an adequate drainage system for the heap structure 2 at Sarcheshmeh copper mine is presented and the results are compared with those calculated by exiting equations.

  7. Evaluation of Critical Parameters to Improve Slope Drainage System

    Directory of Open Access Journals (Sweden)

    Yong Weng Long


    Full Text Available This study focuses on identifying and evaluating critical parameters of various drainage configurations, arrangement, and filter which affect the efficiency of water draining system in slopes. There are a total of seven experiments with different types of homogeneous soil, drainage envelope, filter material, and quantity of pipes performed utilizing a model box with a dimension of 0.8 m × 0.8 m × 0.6 m. The pipes were orientated at 5 degrees from the horizontal. Rainfall event was introduced via a rainfall simulator with rainfall intensity of 434.1 mm/h. From the experiments performed, the expected outcomes when utilizing double pipes and geotextile as envelope filter were verified in this study. The results obtained from these experiments were reviewed and compared with Chapter 14 “Subsurface Drainage Systems” of DID’s Irrigation and Agricultural Drainage Manual of Malaysia and the European standard. It is recommended that the pipe installed in the slope could be wrapped with geotextile and in tandem with application of granular filter to minimize clogging without affecting the water discharge rate. Terzaghi’s filter criteria could be followed closely when deciding on new materials to act as aggregate filter. A caging system could be introduced as it could maintain the integrity of the drainage system and could ease installation.

  8. Analysis of subglacial hydrodynamics and ice dynamics through combined terrestrial laser scanning and ground penetrating radar survey (United States)

    Gabbud, Chrystelle; Rüttimann, Sébastien; Micheletti, Natan; Irving, James; Lane, Stuart


    This study shows how high resolution surveys of subglacial channel morphology combined with high resolution terrestrial laser scanner survey of an Alpine glacier help to understand subglacial hydrological forcing of ice dynamics. The study area is the Haut Glacier d'Arolla in Switzerland, an Alpine valley glacier for which subglacial drainage system has been well studied. A new generation of terrestrial laser scanners was used to investigate glacier surface ablation and other elements of glacial hydrodynamics at exceptionally high spatial and temporal resolution. The LiDAR RIEGL VZ-6000 scanner, with a laser 3B specifically designed for measurements of snow and ice cover surfaces, was tested at seasonal and daily scales. The data revealed spatial variations in the patterns of surface melt, controlled by both aspect and differential debris cover at the seasonal scale, and controlled by ogive-related differences in ice surface debris content at the daily scale. More tentatively, intra-daily scale measurements pointed to possible hydraulic jacking of the glacier associated with short-term water pressure rises at the downstream part of the glacier. A ground-penetrating radar (GPR) field campaign was conducted a year later in the location where possible hydraulic jacking had been detected previously. The aims of this campaign were (i) to assess GPR usage for subglacial channel detection; (ii) identify more precisely the channel morphology; and (iii) investigate further the hydraulic jacking hypothesis. 100 MHz antennas were used to map a 240 x 34 m area near the glacier snout where the ice thickness did not exceed 50 m. The corresponding data, after processing, allowed reconstruction of the bed topography and the morphology of subglacial channels in 3D, showing two of the latter in this area. One channel was followed for approximately 20 m upglacier and corresponding morphology estimates were performed. These data allowed for 3D reconstructions of both the bed

  9. Evaluation of the sustainability of road drainage systems (United States)

    García-Diez, Iván; Palencia, Covadonga; Fernández Raga, María


    Water is the most erosive agent that exists on the linear structures, because they are constantly subjected to outdoor condition like irregular infiltration, frosts and different rain intensities. Another variables that highly influence in the entire lifetime of a natural drainage system are the spatial and temporal variability of the rainfall, the soil, the vegetation cover and the design. All this factors are affecting the vulnerability of the clearings and embankments, by wearing away the weakest materials which surround the roads or train rails, producing erosion and very bumpy surfaces. The result is that the original pattern, developped to disminished the lost of soil, is not properly working and it cannot eliminate water, with the consequence destruction of the linear structure after several rainfall periods, and the accumulation of material down slope. The propose of this research focuses on analysing the drainage systems used in spanish roads and railways lines. For this purpose, a revision of the literature has been done, and the main drainage solutions have been recovered, carrying out an evaluation of them from an environmental point of view. This procedure has been requested by several authors in the past (Nwa, E.U. & Twocock, J.G., 1969; Goulter, I.C., 1992), together with the need of designing a more sustainable drainage system. The final objective of this complete revision is to compare objetively the designs to valuate them in order to develop a new drainage patter which minimize the erosion, increasing the durability and effectiveness of the drainage system. For this purpose, it is neccesary to assure that all the systems will be compare under similar parameters of flow rate, vegetation, substrate, lenght, slope and total section. Only the channels pattern and water distribution will change. The analysis has been done following Liu, H. & Zhu, X.B., (2012), who pointed out that the main parameters to take into account to select a road drainage

  10. Management of chronic subdural haematoma: burr hole drainage, replacement with Hartmann's solution, and closed-system drainage. (United States)

    Aung; Wong; Mo; Tsang


    Although the treatment of chronic subdural haematoma by burr hole drainage has been performed in the past with or without using a closed drainage system, the problem of intracranial air entrapment still persists and can cause a deterioration in the level of consciousness or seizures in the postoperative period. Cerebral infarction may also develop a few days after surgery because of the intracranial hypotension that occurs during the drainage procedure. In an attempt to minimise these complications and to prevent cerebral infarction and its attendant morbidity, we have developed a technique of treating chronic subdural haematoma-namely, performing burr hole drainage, irrigation and replacement of the haematoma with Hartmann's solution, and closed-system drainage of the subdural space with a silicone catheter. The blood pressure is closely monitored and maintained by the infusion of fluids throughout the procedure. An illustrative case using this technique is presented in this paper.

  11. Implementation of a drainage information, analysis and management system

    Directory of Open Access Journals (Sweden)

    J.N. Meegoda


    Full Text Available An integrated drainage information, analysis and management system (DIAMS was developed and implemented for the New Jersey Department of Transportation (NJDOT. The purpose of the DIAMS is to provide a useful tool for managers to evaluate drainage infrastructure, to facilitate the determination of the present costs of preserving those infrastructures, and to make decisions regarding the optimal use of their infrastructure budgets. The impetus for DIAMS is the culvert information management system (CIMS, which is developed to manage the data for culvert pipes. DIAMS maintains and summarizes accumulated inspection data for all types of drainage infrastructure assets, including pipes, inlet/outlet structures, outfalls and manufactured treatment devices. DIAMS capabilities include identifying drainage infrastructure, maintaining inspection history, mapping locations, predicting service life based on the current condition states, and assessing present asset value. It also includes unit cost values of 72 standard items to estimate the current cost for new assets with the ability to adjust for future inflation. In addition, DIAMS contains several different repair, rehabilitation and replacement options to remedy the drainage infrastructure. DIAMS can analyze asset information and determine decisions to inspect, rehabilitate, replace or do nothing at the project and network levels by comparing costs with risks and failures. Costs may be optimized to meet annual maintenance budget allocations by prioritizing drainage infrastructure needing inspection, cleaning and repair. DIAMS functional modules include vendor data uploading, asset identification, system administration and financial analysis. Among the significant performance feature of DIAMS is its proactive nature, which affords decision makers the means of conducting a comprehensive financial analysis to determine the optimal proactive schedule for the proper maintenance actions and to prioritize them

  12. A model for fluid drainage by the lymphatic system. (United States)

    Heppell, Charles; Richardson, Giles; Roose, Tiina


    This study investigates the fluid flow through tissues where lymphatic drainage occurs. Lymphatic drainage requires the use of two valve systems, primary and secondary. Primary valves are located in the initial lymphatics. Overlapping endothelial cells around the circumferential lining of lymphatic capillaries are presumed to act as a unidirectional valve system. Secondary valves are located in the lumen of the collecting lymphatics and act as another unidirectional valve system; these are well studied in contrast to primary valves. We propose a model for the drainage of fluid by the lymphatic system that includes the primary valve system. The analysis in this work incorporates the mechanics of the primary lymphatic valves as well as the fluid flow through the interstitium and that through the walls of the blood capillaries. The model predicts a piecewise linear relation between the drainage flux and the pressure difference between the blood and lymphatic capillaries. The model describes a permeable membrane around a blood capillary, an elastic primary lymphatic valve and the interstitium lying between the two.

  13. Plug identification in drainage system using electromagnetic wave (United States)

    Hijriani, Arifa; Utama, Aji Surya; Boas, Andrianus; Mukti, M. Ridho; Widodo


    The evaluation of drainage system's performance is an important thing to do to prevent flooding. Conventionally the Government evaluates the drainage system by opening one by one the lid of drainage and detects the plug manually. This method is not effective and efficient because this method need many people, much time and relatively expensive. The purpose of this paper is to identify plugs in drainage system in G St. at Bandung Institute of Technology by using electromagnetic wave. Ground Penetrating Radar (GPR) is one of geophysics method that using electromagnetic wave with high frequency. GPR is a non-destructive method with high resolution imaging for shallow depth (˜100m) and relatively cheap. We could identify the plug without opening the lid manually so that we could save much time. GPR's sensitivity is depends on resistivity, magnetic permeability, and permittivity of an object. The result of this research is we could identify the plug on the radargram that observed by a build-up amplitude anomaly.

  14. Vulnerability Analysis of Urban Drainage Systems: Tree vs. Loop Networks

    Directory of Open Access Journals (Sweden)

    Chi Zhang


    Full Text Available Vulnerability analysis of urban drainage networks plays an important role in urban flood management. This study analyzes and compares the vulnerability of tree and loop systems under various rainfall events to structural failure represented by pipe blockage. Different pipe blockage scenarios, in which one of the pipes in an urban drainage network is assumed to be blocked individually, are constructed and their impacts on the network are simulated under different storm events. Furthermore, a vulnerability index is defined to measure the vulnerability of the drainage systems before and after the implementation of adaptation measures. The results obtained indicate that the tree systems have a relatively larger proportion of critical hydraulic pipes than the loop systems, thus the vulnerability of tree systems is substantially greater than that of the loop systems. Furthermore, the vulnerability index of tree systems is reduced after they are converted into a loop system with the implementation of adaptation measures. This paper provides an insight into the differences in the vulnerability of tree and loop systems, and provides more evidence for development of adaptation measures (e.g., tanks to reduce urban flooding.

  15. Links Between Acceleration, Melting, and Supraglacial Lake Drainage of the Western Greenland Ice Sheet (United States)

    Hoffman, M. J.; Catania, G. A.; Newmann, T. A.; Andrews, L. C.; Rumrill, J. A.


    The impact of increasing summer melt on the dynamics and stability of the Greenland Ice Sheet is not fully understood. Mounting evidence suggests seasonal evolution of subglacial drainage mitigates or counteracts the ability of surface runoff to increase basal sliding. Here, we compare subdaily ice velocity and uplift derived from nine Global Positioning System stations in the upper ablation zone in west Greenland to surface melt and supraglacial lake drainage during summer 2007. Starting around day 173, we observe speedups of 6-41% above spring velocity lasting approximately 40 days accompanied by sustained surface uplift at most stations, followed by a late summer slowdown. After initial speedup, we see a spatially uniform velocity response across the ablation zone and strong diurnal velocity variations during periods of melting. Most lake drainages were undetectable in the velocity record, and those that were detected only perturbed velocities for approximately 1 day, suggesting preexisting drainage systems could efficiently drain large volumes of water. The dynamic response to melt forcing appears to 1) be driven by changes in subglacial storage of water that is delivered in diurnal and episodic pulses, and 2) decrease over the course of the summer, presumably as the subglacial drainage system evolves to greater efficiency. The relationship between hydrology and ice dynamics observed is similar to that observed on mountain glaciers, suggesting that seasonally large water pressures under the ice sheet largely compensate for the greater ice thickness considered here. Thus, increases in summer melting may not guarantee faster seasonal ice flow.

  16. Geoethical Approach to Antarctic Subglacial Lakes Exploration (United States)

    Talalay, Pavel; Markov, Alexey; Sysoev, Mikhail


    Antarctic subglacial aquatic environment have become of great interest to the science community because they may provide unique information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet. Nowadays it is generally recognized that a vast network of lakes, rivers, and streams exists thousands of meters beneath Antarctic Ice Sheets. Up to date only four boreholes accessed subglacial aquatic system but three of them were filled with high-toxic drilling fluid, and the subglacial water was contaminated. Two recent exploration programs proposed by UK and USA science communities anticipated direct access down to the lakes Ellsworth and Whillans, respectively, in the 2012/2013 Antarctic season. A team of British scientists and engineers engaged in the first attempt to drill into Lake Ellsworth but failed. US research team has successfully drilled through 800 m of Antarctic ice to reach a subglacial lake Whillans and retrieve water and sediment samples. Both activities used hot-water drilling technology to access lakes. Hot water is considered by the world science community as the most clean drilling fluid medium from the present point of view but it cannot solve environmental problems in total because hot-water even when heated to 90 °C, filtered to 0.2 μm, and UV treated at the surface could pick up microorganisms from near-surface snow and circulate them in great volume through the borehole. Another negative impact of hot-water circulation medium is thermal pollution of subglacial water. The new approach to Antarctic subglacial lakes exploration is presented by sampling technology with recoverable autonomous sonde which is equipped by two hot-points with heating elements located on the bottom and top sides of the sonde. All down-hole sonde components will be sterilized by combination of chemical wash, HPV and UV sterilization prior using. At the beginning of the summer season sonde is installed on the surface of the

  17. Approach for evaluating inundation risks in urban drainage systems. (United States)

    Zhu, Zhihua; Chen, Zhihe; Chen, Xiaohong; He, Peiying


    Urban inundation is a serious challenge that increasingly confronts the residents of many cities, as well as policymakers. Hence, inundation evaluation is becoming increasingly important around the world. This comprehensive assessment involves numerous indices in urban catchments, but the high-dimensional and non-linear relationship between the indices and the risk presents an enormous challenge for accurate evaluation. Therefore, an approach is hereby proposed to qualitatively and quantitatively evaluate inundation risks in urban drainage systems based on a storm water management model, the projection pursuit method, the ordinary kriging method and the K-means clustering method. This approach is tested using a residential district in Guangzhou, China. Seven evaluation indices were selected and twenty rainfall-runoff events were used to calibrate and validate the parameters of the rainfall-runoff model. The inundation risks in the study area drainage system were evaluated under different rainfall scenarios. The following conclusions are reached. (1) The proposed approach, without subjective factors, can identify the main driving factors, i.e., inundation duration, largest water flow and total flood amount in this study area. (2) The inundation risk of each manhole can be qualitatively analyzed and quantitatively calculated. There are 1, 8, 11, 14, 21, and 21 manholes at risk under the return periods of 1-year, 5-years, 10-years, 20-years, 50-years and 100-years, respectively. (3) The areas of levels III, IV and V increase with increasing rainfall return period based on analyzing the inundation risks for a variety of characteristics. (4) The relationships between rainfall intensity and inundation-affected areas are revealed by a logarithmic model. This study proposes a novel and successful approach to assessing risk in urban drainage systems and provides guidance for improving urban drainage systems and inundation preparedness. Copyright © 2016 Elsevier B.V. All

  18. Drainage-system development in consecutive melt seasons at a polythermal, Arctic glacier, evaluated by flow-recession analysis and linear-reservoir simulation. (United States)

    Hodgkins, Richard; Cooper, Richard; Tranter, Martyn; Wadham, Jemma


    [1] The drainage systems of polythermal glaciers play an important role in high-latitude hydrology, and are determinants of ice flow rate. Flow-recession analysis and linear-reservoir simulation of runoff time series are here used to evaluate seasonal and inter-annual variability in the drainage system of the polythermal Finsterwalderbreen, Svalbard, in 1999 and 2000. Linear-flow recessions are pervasive, with mean coefficients of a fast reservoir varying from 16 (1999) to 41 h (2000), and mean coefficients of an intermittent, slow reservoir varying from 54 (1999) to 114 h (2000). Drainage-system efficiency is greater overall in the first of the two seasons, the simplest explanation of which is more rapid depletion of the snow cover. Reservoir coefficients generally decline during each season (at 0.22 h d(-1) in 1999 and 0.52 h d(-1) in 2000), denoting an increase in drainage efficiency. However, coefficients do not exhibit a consistent relationship with discharge. Finsterwalderbreen therefore appears to behave as an intermediate case between temperate glaciers and other polythermal glaciers with smaller proportions of temperate ice. Linear-reservoir runoff simulations exhibit limited sensitivity to a relatively wide range of reservoir coefficients, although the use of fixed coefficients in a spatially lumped model can generate significant subseasonal error. At Finsterwalderbreen, an ice-marginal channel with the characteristics of a fast reservoir, and a subglacial upwelling with the characteristics of a slow reservoir, both route meltwater to the terminus. This suggests that drainage-system components of significantly contrasting efficiencies can coexist spatially and temporally at polythermal glaciers.

  19. Structure and evolution of the drainage system of a Himalayan debris-covered glacier, and its relationship with patterns of mass loss

    Directory of Open Access Journals (Sweden)

    D. I. Benn


    Full Text Available We provide the first synoptic view of the drainage system of a Himalayan debris-covered glacier and its evolution through time, based on speleological exploration and satellite image analysis of Ngozumpa Glacier, Nepal. The drainage system has several linked components: (1 a seasonal subglacial drainage system below the upper ablation zone; (2 supraglacial channels, allowing efficient meltwater transport across parts of the upper ablation zone; (3 sub-marginal channels, allowing long-distance transport of meltwater; (4 perched ponds, which intermittently store meltwater prior to evacuation via the englacial drainage system; (5 englacial cut-and-closure conduits, which may undergo repeated cycles of abandonment and reactivation; and (6 a "base-level" lake system (Spillway Lake dammed behind the terminal moraine. The distribution and relative importance of these elements has evolved through time, in response to sustained negative mass balance. The area occupied by perched ponds has expanded upglacier at the expense of supraglacial channels, and Spillway Lake has grown as more of the glacier surface ablates to base level. Subsurface processes play a governing role in creating, maintaining, and shutting down exposures of ice at the glacier surface, with a major impact on spatial patterns and rates of surface mass loss. Comparison of our results with observations on other glaciers indicate that englacial drainage systems play a key role in the response of debris-covered glaciers to sustained periods of negative mass balance.

  20. Seismic Tremor Reveals Subglacial Discharge at Tidewater Glaciers (United States)

    Bartholomaus, T. C.; Larsen, C. F.; O'Neel, S.; West, M. E.; Amundson, J. M.; Walter, J. I.; Catania, G. A.; Stearns, L. A.; Walker, R. T.; Sutherland, D.; Shroyer, E.; Nash, J. D.


    Subglacial discharge from the termini of tidewater glaciers drives submarine terminus melting, influences fjord circulation, erodes and redeposits subglacial sediment, and is a central component of proglacial marine ecosystems. The timing and variability of subglacial discharge can also exert a strong influence on the upstream flow of tidewater glaciers through hydrology-mediated changes in basal motion. However, a lack of observations of subglacial discharge at the ice-ocean interface hinders progress in understanding these processes and contributes to some of the largest uncertainties in sea level rise projections. Here we demonstrate that passive seismic observations collected adjacent to glaciers can meet this observational need. At tidewater and lake-terminating glaciers in Alaska and Greenland, we observe hourly to seasonal variations in low-amplitude, background seismic noise, termed glacio-hydraulic tremor. Variations in tremor amplitude correlate with discharge during the drainage of a glacially-dammed lake and reveal increases in discharge efficiency over the course of the melt season. Recordings of glacio-hydraulic tremor across a range of settings suggest widespread utility for our method. Reliable prediction of future sea level rise requires observations of subglacial discharge that elicit physical insight and can validate models. Our findings provide a platform for new understanding of ice-ocean interactions and related oceanographic, geologic, and ecological disciplines.

  1. Open Drainage and Detention Basin Combined System Optimization

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    M. E. Banihabib


    Full Text Available Introduction: Since flooding causes death and economic damages, then it is important and is one of the most complex and destructive natural disaster that endangers human lives and properties compared to any other natural disasters. This natural disaster almost hit most of countries and each country depending on its policy deals with it differently. Uneven intensity and temporal distribution of rainfall in various parts of Iran (which has arid and semiarid climate causes flash floods and leads to too much economic damages. Detention basins can be used as one of the measures of flood control and it detains, delays and postpones the flood flow. It controls floods and affects the flood directly and rapidly by temporarily storing of water. If the land topography allows the possibility of making detention basin with an appropriate volume and quarries are near to the projects for construction of detention dam, it can be used, because of its faster effect comparing to the other watershed management measures. The open drains can be used alone or in combination with detention basin instead of detention basin solitarily. Since in the combined system of open and detention basin the dam height is increasing in contrast with increasing the open drainage capacity, optimization of the system is essential. Hence, the investigation of the sensitivity of optimized combined system (open drainage and detention basin to the effective factors is also useful in appropriately design of the combined system. Materials and Methods: This research aims to develop optimization model for a combined system of open drainage and detention basins in a mountainous area and analyze the sensitivity of optimized dimensions to the hydrological factors. To select the dam sites for detention basins, watershed map with scale of 1: 25000 is used. In AutoCAD environment, the location of the dam sites are assessed to find the proper site which contains enough storage volume of the detention

  2. Modeling Subglacial Permafrost Evolution (United States)

    Koutnik, M. R.; Marshall, S.


    Permanently frozen ground was present both beneath and peripheral to the Quaternary ice sheets. In areas where the ice sheet grew or advanced over permafrost, the ice sheet insulated the ground, leading to subglacial permafrost degradation. This has created distinct signatures of ice sheet occupation in the Canadian north and in Alaska during the last glacial period, with greatly diminished permafrost thickness in regions that were ice covered for an extended period. In contrast, areas peripheral to the ice sheet, including the Midwest United States, were cooled by the glacial climate conditions and the regional cooling influence of the ice sheet, leading to permafrost growth. We have developed a sub- and proglacial diffusion based permafrost model that utilizes a logarithmic grid transformation to more efficiently track the changing depth of permafrost with time. This model is coupled with the ice sheet thermodynamic model of Marshall and Clarke [1997a] to explore the geologic signatures of the last glacial cycle in North America. This offers the potential for new constraints on modeled ice sheet history. Preliminary model runs show that the overlying ice sheet has a significant effect on the underlying and peripheral permafrost degradation and formation. Subglacial permafrost is also important because its evolution influences the basal temperature of the ice sheet, critical for evolution of subglacial hydrology and fast flow instabilities (e.g. ice streams). We present results of permafrost conditions under the last glacial maximum ice sheet and the effect of permafrost on basal temperature evolution through the last glacial cycle in North America. Marshall, S. J. and G. K. C. Clarke, 1997a. J. Geophys. Res., 102 (B9), 20,599-20,614.

  3. Regional view of a Trans-African Drainage System

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    Mohamed Abdelkareem


    Full Text Available Despite the arid to hyperarid climate of the Great Sahara of North Africa, pluvial climates dominated the region. Radar data shed some light on the postulated Trans-African Drainage System and its relationship to active and inactive tributaries of the Nile basin. Interpretations of recent elevation data confirm a source of the river water from the Red Sea highlands did not connect the Atlantic Ocean across Tushka basin, highlands of Uwinate and Darfur, and Chad basin, but northward to the ancestral Nile Delta. Elements of topography and climate were considered. They show that the former segments of the Nile closely mirror present-day tributaries of the Nile basin in drainage geometry, landscape, and climate. A rainfall data interpolation scenario revealed that this basin received concurrent runoff from both flanks such as Gabgaba-Allaqi to the east and Tushka basin to the west, similar to present-day Sobat and White Nile tributaries, respectively. Overall the western tributaries such as those of Tushka basin and Howar lead to the Nile, which was (and still is the biggest river system in Africa.

  4. Non-stationary behavior of roof drainage systems

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    Koláček Martin


    Full Text Available This paper reports the non-stationary behavior of a roof drainage during experimental measurement in the climate simulator. Many buildings use a fully or partially flat roof where it is necessary to use the roof drainage. Thermal behavior of roof drainage is very important from the point of view of heat transfer and potential condensation. The placement of a roof drain slightly deteriorates thermal transmittance of the roof. This experiment evaluates roof drains in the specific climate simulator where thermal conditions were dynamically controlled in the specific temperature range. The measurement was performed for two types of roof drains. The first drainage is a simple single-shell and the second is double-shell drainage. The results show the effect on the thermal transmittance of the roof section and also the minimal effect of condensation on the non-insulation part of the drainage. Both roof drains showed minimal deterioration of thermal transmittance of the roof construction.

  5. Design and performance of materials for subsurface drainage systems in agriculture

    NARCIS (Netherlands)

    Stuyt, L.C.P.M.; Dierickx, W.


    During the second half of the 20th century, numerous land drainage systems using new materials for the drain channels that often function inadequately due to biochemical and mechanical clogging, were developed. The design of drainpipes and envelope materials used for these land drainage systems was

  6. Subglacial till formation: Microscale processes within the subglacial shear zone (United States)

    Hart, Jane K.


    This was a study of subglacial deformation till genesis from a modern temperate glacier, at Skálafellsjökull, Iceland. Detailed microscale properties of till samples (from Scanning Electron Microscope [SEM] and thin section analysis) were examined from a glacial site with in situ subglacial process monitoring and an exposed subglacial surface in the foreland. Two lithofacies were examined, a grey sandy till derived from the ash and basalt, and a silty reddish brown till derived from oxidized paleosols and/or tephra layers. These also represented a clay-content continuum from low (0.3%) to high (22.3%). The evolution from debris to subglacial till was investigated. This included a reduction in grain-size (21% for grey lithology, 13% reddish brown lithology), and reduction in rounding (RA) (32% for the grey lithology, 26% for the reddish brown lithology), and the quantification and analysis of the different grain erosion/comminution processes in the resultant till. It was shown that the microstructures within a till were dependent on shear strain and glaciological conditions (deformation history). The low clay content tills were dominated by linear structures (lineations and boudins, and anisotropic microfabric) whilst the higher clay content tills were dominated by rotational structures (turbates and plaster, and isotropic microfabric). These results are important in our understanding of the formation of both modern and Quaternary tills and informs our reconstruction of past glacial dynamics.

  7. Physiological utility of ultrasound biomicroscopy in the lacrimal drainage system. (United States)

    Al-Faky, Yasser H


    To evaluate lacrimal sac (LS) pump failure in patients with lower motor neuron facial nerve palsy (FNP) using ultrasound biomicroscopy (UBM). This was a prospective observational case series. Patients with unilateral lower motor neuron FNP of different aetiologies, age groups and gender were enrolled in this study. Anatomical patency was confirmed through irrigation of the lacrimal drainage system. The degree of lagophthalmos and House-Brackmann grade (HBG) were evaluated, and the dye disappearance test performed. UBM evaluation of the LS during opening and closure of the eyelids was performed for both sides; the control side and the side with assumed lacrimal pump failure (attributed to FNP). Any changes in the orbicularis oculi muscle and fluid turbulence within the sac were reported. A total of 17 patients with unilateral lower motor neuron FNP were evaluated. The average age (± SD) was 33.2 ± 20.1 years. UBM evaluation of control side LS showed obvious fluid turbulence of different patterns within the sac during opening and closure of the eyelids. Fluid turbulence was absent in the LS with HBG V and VI FNP and reduced in the LS with HBG III and IV FNP. UBM can be used as a safe, non-invasive and office-based tool to evaluate the LS pump.

  8. Contamination of Detained Sediment in Sustainable Urban Drainage Systems

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    Deonie Allen


    Full Text Available Adsorption is a key water pollution remediation measure used to achieve stormwater quality improvement in Sustainable urban Drainage Systems (SuDS. The level of contamination of detained sediment within SuDS assets is not well documented, with published investigations limited to specific contaminant occurrence in ponds, wetlands or infiltration devices (bioretention cells and generally focused on solute or suspended sediment. Guidance on contamination threshold levels and potential deposited sediment contamination information is not included in current UK SuDS design or maintenance guidance, primarily due to a lack of evidence and understanding. There is a need to understand possible deposited sediment contamination levels in SuDS, specifically in relation to sediment removal maintenance activities and potential impact on receiving waterways of conveyed sediment. Thus, the objective of the research presented herein was to identify what major elements and trace metals were observable in (the investigated SuDS assets detained sediment, the concentration of these major elements and trace metals and whether they met/surpassed ecotoxicity or contaminated land thresholds. The research presented here provides evidence of investigated SuDS sediment major element and trace metal levels to help inform guidance and maintenance needs, and presents a new methodology to identify the general cause (anthropocentric land use and extent of detained SuDS fine urban sediment contamination through use of a contamination matrix.

  9. Discharge characteristics of four highway drainage systems in Ohio (United States)

    Straub, D.E.


    Excessive water in the subbase of high-way combined with large traffic volumes and heavy loads is a major cause of road deterioration. Prompt removal of any excess water in a subbase will decrease the road deterioration and extend the effective life of a highway. This study presents discharge characteristics of four highway subbase drainage systems. These systems consisted of shallow, longitudal trenches with geocomposite drain materials (edge drains made from a polyethylene core surrounded by a geotextile filter fabric) that underline the joint between the shoulder and the traffic lane of State Route 16, approximately 1.0 mile southeast of Granville, Ohio. For selected rainfall-runoff events the maximum discharge, discharge characteristics from April 1991 through November 1993 were computed for three geocomposite products- a post type, an oblong-pipe type, and a cusp type-and a conventional perforated pipe edge drain. In general, the discharge characteristics of the conventional edge drain and that of the oblong-pipe edge drain were similar for most of the rainfall-runoff event characteristics. Both produced most of the highest maximum discharges and largest discharge volumes among the four longitudal edge drains. The post edge drain produced smaller maximum discharge and volumes than the conventional and oblong-pipe edge drains, but it had the shortest lag times for most of the event characteristics. The cusp edge drain produced small maximum discharges and small volumes similar to those from the post edge drain, but it had the longest lag times of all the edge drains for most of the event characteristics. The cusp edge drain may have also had some problems during installation which could have affected the discharge characteristics.

  10. Stochastic long term modelling of a drainage system with estimation of return period uncertainty

    DEFF Research Database (Denmark)

    Thorndahl, Søren


    periods of drainage system predictions are based on ranking, but this paper proposes a new methodology for the assessment of return periods. Based on statistics of characteristic rainfall parameters and correlation with drainage system predictions, it is possible to predict return periods more reliably......Long term prediction of maximum water levels and combined sewer overflow (CSO) in drainage systems are associated with large uncertainties. Especially on rainfall inputs, parameters, and assessment of return periods. This paper proposes a Monte Carlo based methodology for stochastic prediction......, and with smaller confidence bands compared to the traditional methodology....

  11. Stochastic Long Term Modelling of a Drainage System with Estimation of Return Period Uncertainty

    DEFF Research Database (Denmark)

    Thorndahl, Søren


    periods of drainage system predictions are based on ranking, but this paper proposes a new methodology for the assessment of return periods. Based on statistics of characteristic rainfall parameters and correlation with drainage system predictions, it is possible to predict return periods more reliably......Long term prediction of maximum water levels and combined sewer overflow (CSO) in drainage systems are associated with large uncertainties. Especially on rainfall inputs, parameters, and assessment of return periods. This paper proposes a Monte Carlo based methodology for stochastic prediction......, and with smaller confidence bands compared to the traditional methodology....

  12. A Two-Stage Queue Model to Optimize Layout of Urban Drainage System considering Extreme Rainstorms

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    Xinhua He


    Full Text Available Extreme rainstorm is a main factor to cause urban floods when urban drainage system cannot discharge stormwater successfully. This paper investigates distribution feature of rainstorms and draining process of urban drainage systems and uses a two-stage single-counter queue method M/M/1→M/D/1 to model urban drainage system. The model emphasizes randomness of extreme rainstorms, fuzziness of draining process, and construction and operation cost of drainage system. Its two objectives are total cost of construction and operation and overall sojourn time of stormwater. An improved genetic algorithm is redesigned to solve this complex nondeterministic problem, which incorporates with stochastic and fuzzy characteristics in whole drainage process. A numerical example in Shanghai illustrates how to implement the model, and comparisons with alternative algorithms show its performance in computational flexibility and efficiency. Discussions on sensitivity of four main parameters, that is, quantity of pump stations, drainage pipe diameter, rainstorm precipitation intensity, and confidence levels, are also presented to provide guidance for designing urban drainage system.

  13. Review on the quality of sediments from the stormwater drainage system in the urban area

    Directory of Open Access Journals (Sweden)

    Nawrot Nicole


    Full Text Available The main task of the stormwater drainage system (SDS is a safe drainage of rainwater and snowmelt from the urban area to the receiver. The flow of rain water in the drainage pipes is directly related with the formation of sediments in the whole stormwater system. In addition, pollutants from land runoff get adsorbed to the sediments. The sludge is mainly formed in those elements of SDS, wherein the flow conditions allow for sedimentation. This article provides an overview of the literature concerning the characteristics of sediments from SDS, with a particular focus on heavy metals in sediments deposited in the urban catchment area.

  14. Ice thickness, volume and subglacial topography of Urumqi Glacier ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 123; Issue 3. Ice thickness, volume and subglacial topography of Urumqi Glacier No. 1, Tianshan mountains, central Asia, by ground penetrating radar survey. Puyu Wang Zhongqin Li Shuang Jin Ping Zhou Hongbing Yao Wenbin Wang. Volume 123 Issue 3 April ...

  15. A wireless subglacial probe for deep ice applications

    NARCIS (Netherlands)

    Smeets, C.J.P.P.|info:eu-repo/dai/nl/191522236; Boot, W.; Hubbard, A.; Pettersson, R.; Wilhelms, F.; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; van de Wal, R.S.W.|info:eu-repo/dai/nl/101899556


    We present the design and first results from two experiments using a wireless subglacial sensor system (WiSe) that is able to transmit data through 2500m thick ice. Energy consumption of the probes is minimized, enabling the transmission of data for at least 10 years. In July 2010 the first

  16. Landscape evolution by subglacial quarrying

    DEFF Research Database (Denmark)

    Ugelvig, Sofie Vej; Egholm, D.L.; Iverson, Neal R.

    of sliding and erosion is not well supported when considering models for quarrying of rock blocks from the bed. Iverson (2012) introduced a new subglacial quarrying model that operates from the theory of adhesive wear. The model is based on the fact that cavities, with a high level of bedrock differential...... to a model for glacial hydrology. In order to also include the effects of cavitation on the subglacial sliding rate, we use a sliding law proposed by Schoof (2005), which includes an upper limit for the stress that can be supported at the bed. Computational experiments show that the combined influence...... evolution models. Geology, v. 40, no. 8, 679-682 (2012). Schoof, C. The effect of cavitation on glacier sliding. Proc. R. Soc. A , 461, 609-627 (2005). Jaeger, J.C., and Cook, N.G.W. Fundamentals of rock mechanics: New York, Chapman and Hall, 593 p. (1979)...

  17. Urban drainage system planning and design--challenges with climate change and urbanization: a review. (United States)

    Yazdanfar, Zeinab; Sharma, Ashok


    Urban drainage systems are in general failing in their functions mainly due to non-stationary climate and rapid urbanization. As these systems are becoming less efficient, issues such as sewer overflows and increase in urban flooding leading to surge in pollutant loads to receiving water bodies are becoming pervasive rapidly. A comprehensive investigation is required to understand these factors impacting the functioning of urban drainage, which vary spatially and temporally and are more complex when weaving together. It is necessary to establish a cost-effective, integrated planning and design framework for every local area by incorporating fit for purpose alternatives. Carefully selected adaptive measures are required for the provision of sustainable drainage systems to meet combined challenges of climate change and urbanization. This paper reviews challenges associated with urban drainage systems and explores limitations and potentials of different adaptation alternatives. It is hoped that the paper would provide drainage engineers, water planners, and decision makers with the state of the art information and technologies regarding adaptation options to increase drainage systems efficiency under changing climate and urbanization.

  18. Aspects to consider for optimizing a substrate culture system with drainage recycling

    Directory of Open Access Journals (Sweden)

    William J Cuervo B


    Full Text Available In Colombia, the soilless system has been implemented in the cut flowers industry, among others, due to soil limitations. The use of substrates as growing media implies to drain around 30% of the applied fertigation solution to avoid the rhizosphere salinization. The drainage solution is spilled out to the soil producing environmental hazards and it might reach the water table; although the drainage solution could be recycled or reuse, depending upon their chemical characteristics. The nutrient uptake by the plants depends upon their phenological stage and the nutrient concentration in the solution; which could lead to ion depletion or accumulation. In general, monovalent ions are withdrawn faster than divalent ones. An efficient drainage treatment involves the automation of sensing and evaluation of ion concentration and recycling the drainage solution. The system should take into account the chemical aspects in the recycled and the new solutions in order to predict the life time of the drainage solution from their EC and pH. The system must be integrated with disinfection methods to avoid the spreading of plant pathogens. This review point out the physiological and technical bases that should be taking into account in a drainage recycling system in established crops under substrates, as a tool to take decisions more efficiently.

  19. Incorporating modelled subglacial hydrology into inversions for basal drag

    Directory of Open Access Journals (Sweden)

    C. P. Koziol


    Full Text Available A key challenge in modelling coupled ice-flow–subglacial hydrology is initializing the state and parameters of the system. We address this problem by presenting a workflow for initializing these values at the start of a summer melt season. The workflow depends on running a subglacial hydrology model for the winter season, when the system is not forced by meltwater inputs, and ice velocities can be assumed constant. Key parameters of the winter run of the subglacial hydrology model are determined from an initial inversion for basal drag using a linear sliding law. The state of the subglacial hydrology model at the end of winter is incorporated into an inversion of basal drag using a non-linear sliding law which is a function of water pressure. We demonstrate this procedure in the Russell Glacier area and compare the output of the linear sliding law with two non-linear sliding laws. Additionally, we compare the modelled winter hydrological state to radar observations and find that it is in line with summer rather than winter observations.

  20. Impacts of climate change on rainfall extremes and urban drainage systems: a review. (United States)

    Arnbjerg-Nielsen, K; Willems, P; Olsson, J; Beecham, S; Pathirana, A; Bülow Gregersen, I; Madsen, H; Nguyen, V-T-V


    A review is made of current methods for assessing future changes in urban rainfall extremes and their effects on urban drainage systems, due to anthropogenic-induced climate change. The review concludes that in spite of significant advances there are still many limitations in our understanding of how to describe precipitation patterns in a changing climate in order to design and operate urban drainage infrastructure. Climate change may well be the driver that ensures that changes in urban drainage paradigms are identified and suitable solutions implemented. Design and optimization of urban drainage infrastructure considering climate change impacts and co-optimizing these with other objectives will become ever more important to keep our cities habitable into the future.

  1. Impacts of climate change on rainfall extremes and urban drainage systems: A review

    DEFF Research Database (Denmark)

    Arnbjerg-Nielsen, Karsten; Willems, P.; Olsson, J.


    A review is made of current methods for assessing future changes in urban rainfall extremes and their effects on urban drainage systems, due to anthropogenic-induced climate change. The review concludes that in spite of significant advances there are still many limitations in our understanding...... of how to describe precipitation patterns in a changing climate in order to design and operate urban drainage infrastructure. Climate change may well be the driver that ensures that changes in urban drainage paradigms are identified and suitable solutions implemented. Design and optimization of urban...... drainage infrastructure considering climate change impacts and co-optimizing these with other objectives will become ever more important to keep our cities habitable into the future. © IWA Publishing 2013....

  2. The Effect of Different Subsurface Drainage Systems on Improvement of Water Flow in Paddy fields

    Directory of Open Access Journals (Sweden)

    ghassem aghajani mazandarani


    Full Text Available Introduction: Better use of water and soil resources in paddy fields, increase in rice production and farmer's income, installation of subsurface drainage system is necessary. The main goalof these systems, are aeration conditions improvement prevention of water logging, yield increase, land use increase and multiuse of the land. In different countries, installation of subsurface drainage cause yield increase and working condition on the land, but no research has been conducted in different depths and spacing. On the other hand, spacing and depth are the most important parameters in the installation of drainage systems, have a direct effect on incoming water into the drains. The aim of this research, is an investigation of the effect of subsurface drainage with different depths and spacing on discharge rate variation and water table fall, in order to analyze the improvement of water flow movement in the soil. Also, study the effect of different drainage systems on the increase of the canola yield as the second cultivation in these treatments have been compared. Materials and Methods: To measure hydraulic conductivity in different depths, the auger holes have been dug (excavated. The saturated hydraulic conductivity in these holes wasdetermined using Ernst method (1950 before installation of drainage systems. In the drainage pilot plot of Sari Agricultural Sciences and Natural Resources University three subsurface drainage systems with mineral envelope have been installed. 1- The first one with the 0.9 m depth and 30 m spacing (D90 L30, 2- The second one with 0.65 m depth and 15 m spacing (D0.65 L15 and 3- The third one with 0.65 m depth and spacing (D0.65 L30 and one bi-level system with mineral envelope including four drains of 15 m spacing with 0.9 m and 0.65 m depths were installed alternatively. After auger hole equipment installations, in the middle spacing of two subsurface and water table reading possible, the water table fluctuation and

  3. Paleo ice flow and subglacial meltwater dynamics in Pine Island Bay, West Antarctica

    Directory of Open Access Journals (Sweden)

    F. O. Nitsche


    Full Text Available Increasing evidence for an elaborate subglacial drainage network underneath modern Antarctic ice sheets suggests that basal meltwater has an important influence on ice stream flow. Swath bathymetry surveys from previously glaciated continental margins display morphological features indicative of subglacial meltwater flow in inner shelf areas of some paleo ice stream troughs. Over the last few years several expeditions to the eastern Amundsen Sea embayment (West Antarctica have investigated the paleo ice streams that extended from the Pine Island and Thwaites glaciers. A compilation of high-resolution swath bathymetry data from inner Pine Island Bay reveals details of a rough seabed topography including several deep channels that connect a series of basins. This complex basin and channel network is indicative of meltwater flow beneath the paleo-Pine Island and Thwaites ice streams, along with substantial subglacial water inflow from the east. This meltwater could have enhanced ice flow over the rough bedrock topography. Meltwater features diminish with the onset of linear features north of the basins. Similar features have previously been observed in several other areas, including the Dotson-Getz Trough (western Amundsen Sea embayment and Marguerite Bay (SW Antarctic Peninsula, suggesting that these features may be widespread around the Antarctic margin and that subglacial meltwater drainage played a major role in past ice-sheet dynamics.

  4. Construction and calibration of weighing lysimeters with an automated drainage system

    Directory of Open Access Journals (Sweden)

    Arthur C. Sanches

    Full Text Available ABSTRACT Quantification of the drained volume is one of the difficulties involved in using weighing lysimeters. Typically, this volume is measured by accessing a moat at the base of a lysimeter. However, it is not feasible to install the moat in small devices. Thus, the aim of this study involves developing, installing, calibrating, and checking the efficiency of small weighing lysimeters with automated drainage systems to test their functionality in field conditions. Each lysimeter is composed of a round PVC water tank with a diameter of 1.22 m and a depth of 0.58 m that is placed over a metal frame with three electronic load cells with the nominal capacity of each cell corresponding to 500 kg. The drainage system is composed of a small reservoir with a volume of 10 L, a weighing structure composed of a load cell with a nominal capacity of 30 kg, and an automatic solenoid valve driven by a device coupled to a data logger that records the data from the lysimeter and from the drainage system. Two calibrations are performed for the lysimeter as well as the drainage system to obtain equations with significant correlations (R2 > 0.9999. The drainage system was activated several times during the tests after receiving approximately 63.4 L of water from rainfall, and this in turn indicated a good performance.

  5. Means to improve underground coal mine safety by automated control of methane drainage systems

    Directory of Open Access Journals (Sweden)

    Babut Gabriel Bujor


    Full Text Available Based on the critical analysis of the presently employed management of methane drainage systems operation in Jiu Valley collieries, the paper aims to assess the basic elements required to develop an automated monitoring and control system of these. The results obtained after studies and researches carried out also allowed formulating certain proposals regarding the modification of manual control procedures of methane drainage systems operation, in order to correlate them with the prescriptions of legislation requirements from countries having a well-developed mining industry. Putting in practice the mentioned proposals could have immediate and beneficial effects on increasing the methane drainage process efficiency, leading meanwhile to an improved working environment and, implicitly, to a higher level of occupational safety and health in Jiu Valley collieries.

  6. Measurement and evaluation of percolation drainage systems capacity in real conditions (United States)

    Markovic, G.; Zelenakova, M.


    The drainage system must ensure a safe disposal of the surface water without endangering the buildings and safety of people. Despite the common use of rainwater infiltration facilities, there is still only limited data available evaluating the long-term capacity of such systems especially for underground infiltration facilities. This study presents experimental measurements and evaluation of long-term infiltration efficiency in real conditions and emphasizes the importance of hydrogeological survey. The measurements of infiltration efficiency were applied to an existing percolation drainage system – infiltration shafts. Infiltration shafts were made in year 2007 so that its drainage operation takes more than 8 years. This study was started in 2011 and still continues and presents 5 years measurements of infiltration efficiency for this infiltration facility.

  7. Runoff and drainage losses of atrazine, metribuzin, and metolachlor in three water management systems. (United States)

    Gaynor, J D; Tan, C S; Drury, C F; Welacky, T W; Ng, H Y F; Reynolds, W D


    Rainfall can transport herbicides from agricultural land to surface waters, where they become an environmental concern. Tile drainage can benefit crop production by removing excess soil water but tile drainage may also aggravate herbicide and nutrient movement into surface waters. Water management of tile drains after planting may reduce tile drainage and thereby reduce herbicide losses to surface water. To test this hypothesis we calculated the loss of three herbicides from a field with three water management systems: free drainage (D), controlled drainage (CD), and controlled drainage with subsurface irrigation (CDS). The effect of water management systems on the dissipation of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine), metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazine-5(4H)-one), and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] in soil was also monitored. Less herbicide was lost by surface runoff from the D and CD treatments than from CDS. The CDS treatment increased surface runoff, which transported more herbicide than that from D or CD treatments. In one year, the time for metribuzin residue to dissipate to half its initial value was shorter for CDS (33 d) than for D (43 d) and CD (46 d). The half-life of atrazine and metolachlor were not affected by water management. Controlled drainage with subsurface irrigation may increase herbicide loss through increased surface runoff when excessive rain is received soon after herbicide application. However, increasing soil water content in CDS may decrease herbicide persistence, resulting in less residual herbicide available for aqueous transport.

  8. Greenland englacial drainage: conditions favoring water transport through a fractured aquifer (United States)

    Creyts, T. T.; Fountain, A. G.


    Recently, the subglacial hydrology of glaciers and ice sheets has garnered intense interest because of its effects on ice sliding and potential ice sheet responses leading to sea level rise. Less attention has focused on the englacial water system that connects surface meltwater sources to the basal drainage system. Observations of englacial drainage have revealed diametrically opposed behaviors, so that understanding the role of the englacial system is critical to developing knowledge of ice sheet responses. The englacial connections either enhance or limit subglacial processes, including sliding. Some observations show cases where water drainage is mainly through an englacial system of fractures so that water flow at the bed is stunted. Other observations show static englacial water systems that play little role in drainage with primary drainage routes being along the bed. Here, we use a thermomechanical model of englacial water flow to understand the interaction between ice and water along these connections. We assume that water flow is through a series of connected fractures analogous to crevassed Greenland outlet glaciers. The fractures are modified by ice flow, and freezing and melting of the water system. Simple mathematical analyses show trade offs between closure rates and melting rates that determine the englacial flowpaths. From numerical experiments, we show that the dominance of englacial flow follows the locations of both bed overdeepenings and areas where the basal water system is compressed dynamically. The preponderance of overdeependenings in Greenland suggests that englacial systems may be favored in critical areas of ice sheet flow. We conclude by relating the insights from the analytic and numerical results to the broad scale patterns of change of the Greenland Ice Sheet.

  9. Using Weather Radar to Optimise Operation of an Urban Drainage System with Distributed Rainwater Storage

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Thorndahl, Søren Liedtke; Bentzen, Thomas Ruby


    The perspective of controlling the local rain water storage tanks for a small catchment is investigated to evaluate if a predictive control reduces the CSO from the storm drainage system. A weather radar based nowcast system is used to predict the actual precipitation two hours ahead. In case...

  10. Unveiling the Antarctic subglacial landscape. (United States)

    Warner, Roland; Roberts, Jason


    Better knowledge of the subglacial landscape of Antarctica is vital to reducing uncertainties regarding prediction of the evolution of the ice sheet. These uncertainties are associated with bedrock geometry for ice sheet dynamics, including possible marine ice sheet instabilities and subglacial hydrological pathways (e.g. Wright et al., 2008). Major collaborative aerogeophysics surveys motivated by the International Polar Year (e.g. ICECAP and AGAP), and continuing large scale radar echo sounding campaigns (ICECAP and NASA Ice Bridge) are significantly improving the coverage. However, the vast size of Antarctica and logistic difficulties mean that data gaps persist, and ice thickness data remains spatially inhomogeneous. The physics governing large scale ice sheet flow enables ice thickness, and hence bedrock topography, to be inferred from knowledge of ice sheet surface topography and considerations of ice sheet mass balance, even in areas with sparse ice thickness measurements (Warner and Budd, 2000). We have developed a robust physically motivated interpolation scheme, based on these methods, and used it to generate a comprehensive map of Antarctic bedrock topography, using along-track ice thickness data assembled for the BEDMAP project (Lythe et al., 2001). This approach reduces ice thickness biases, compared to traditional inverse distance interpolation schemes which ignore the information available from considerations of ice sheet flow. In addition, the use of improved balance fluxes, calculated using a Lagrangian scheme, eliminates the grid orientation biases in ice fluxes associated with finite difference methods (Budd and Warner, 1996, Le Brocq et al., 2006). The present map was generated using a recent surface DEM (Bamber et al., 2009, Griggs and Bamber, 2009) and accumulation distribution (van de Berg et al., 2006). Comparing our results with recent high resolution regional surveys gives confidence that all major subglacial topographic features are

  11. Lymphatic drainage system of the brain: A novel target for intervention of neurological diseases. (United States)

    Sun, Bao-Liang; Wang, Li-Hua; Yang, Tuo; Sun, Jing-Yi; Mao, Lei-Lei; Yang, Ming-Feng; Yuan, Hui; Colvin, Robert A; Yang, Xiao-Yi


    The belief that the vertebrate brain functions normally without classical lymphatic drainage vessels has been held for many decades. On the contrary, new findings show that functional lymphatic drainage does exist in the brain. The brain lymphatic drainage system is composed of basement membrane-based perivascular pathway, a brain-wide glymphatic pathway, and cerebrospinal fluid (CSF) drainage routes including sinus-associated meningeal lymphatic vessels and olfactory/cervical lymphatic routes. The brain lymphatic systems function physiological as a route of drainage for interstitial fluid (ISF) from brain parenchyma to nearby lymph nodes. Brain lymphatic drainage helps maintain water and ion balance of the ISF, waste clearance, and reabsorption of macromolecular solutes. A second physiological function includes communication with the immune system modulating immune surveillance and responses of the brain. These physiological functions are influenced by aging, genetic phenotypes, sleep-wake cycle, and body posture. The impairment and dysfunction of the brain lymphatic system has crucial roles in age-related changes of brain function and the pathogenesis of neurovascular, neurodegenerative, and neuroinflammatory diseases, as well as brain injury and tumors. In this review, we summarize the key component elements (regions, cells, and water transporters) of the brain lymphatic system and their regulators as potential therapeutic targets in the treatment of neurologic diseases and their resulting complications. Finally, we highlight the clinical importance of ependymal route-based targeted gene therapy and intranasal drug administration in the brain by taking advantage of the unique role played by brain lymphatic pathways in the regulation of CSF flow and ISF/CSF exchange. Copyright © 2017. Published by Elsevier Ltd.

  12. Inter-Event Time Definition Setting Procedure for Urban Drainage Systems

    Directory of Open Access Journals (Sweden)

    Jingul Joo


    Full Text Available Traditional inter-event time definition (IETD estimate methodologies generally take into account only rainfall characteristics and not drainage basin characteristics. Therefore, they may not succeed in providing an appropriate value of IETD for any sort of application to the design of urban drainage system devices. To overcome this limitation, this study presents a method of IETD determination that considers basin characteristics. The suggested definition of IETD is the time period from the end of a rainfall event to the end of a direct runoff. The suggested method can identify the independent events that are suitable for the statistical analysis of the recorded rainfall. Using the suggested IETD, the IETD of the Joong-Rang drainage system was determined and the area-IETD relation curve was drawn. The resulting regression curve can be used to determinate the IETD of ungauged urban drainage systems, with areas ranging between 40 and 4400 ha. Using the regression curve, the IETDs and time distribution of the design rainfall for four drainage systems in Korea were determined and rainfall-runoff simulations were performed with the Storm Water Management Model (SWMM. The results were compared with those from Huff's method which assumed a six-hour IETD. The peak flow rates obtained by the suggested method were 11%~15% greater than those obtained by Huff’s method. The suggested IETD determination method can identify independent events that are suitable for the statistical analysis of the recorded rainfall aimed at the design of urban drainage system devices.

  13. Reducing nitrate loss in tile drainage water with cover crops and water-table management systems. (United States)

    Drury, C F; Tan, C S; Welacky, T W; Reynolds, W D; Zhang, T Q; Oloya, T O; McLaughlin, N B; Gaynor, J D


    Nitrate lost from agricultural soils is an economic cost to producers, an environmental concern when it enters rivers and lakes, and a health risk when it enters wells and aquifers used for drinking water. Planting a winter wheat cover crop (CC) and/or use of controlled tile drainage-subirrigation (CDS) may reduce losses of nitrate (NO) relative to no cover crop (NCC) and/or traditional unrestricted tile drainage (UTD). A 6-yr (1999-2005) corn-soybean study was conducted to determine the effectiveness of CC+CDS, CC+UTD, NCC+CDS, and NCC+UTD treatments for reducing NO loss. Flow volume and NO concentration in surface runoff and tile drainage were measured continuously, and CC reduced the 5-yr flow-weighted mean (FWM) NO concentration in tile drainage water by 21 to 38% and cumulative NO loss by 14 to 16% relative to NCC. Controlled tile drainage-subirrigation reduced FWM NO concentration by 15 to 33% and cumulative NO loss by 38 to 39% relative to UTD. When CC and CDS were combined, 5-yr cumulative FWM NO concentrations and loss in tile drainage were decreased by 47% (from 9.45 to 4.99 mg N L and from 102 to 53.6 kg N ha) relative to NCC+UTD. The reductions in runoff and concomitant increases in tile drainage under CC occurred primarily because of increases in near-surface soil hydraulic conductivity. Cover crops increased corn grain yields by 4 to 7% in 2004 increased 3-yr average soybean yields by 8 to 15%, whereas CDS did not affect corn or soybean yields over the 6 yr. The combined use of a cover crop and water-table management system was highly effective for reducing NO loss from cool, humid agricultural soils. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  14. Identifying weak points of urban drainage systems by means of VulNetUD. (United States)

    Möderl, M; Kleidorfer, M; Sitzenfrei, R; Rauch, W


    This article presents the development and application of the software tool VulNetUD. VulNetUD is a tool for GIS-based identification of vulnerable sites of urban drainage systems (UDS) using hydrodynamic simulations undertaken using EPA SWMM. The benefit of the tool is the output of different vulnerability maps rating sewer surcharging, sewer flooding, combined sewer overflow (CSO) efficiency and CSO emissions. For this, seven predefined performance indicators are used to evaluate urban drainage systems under abnormal, critical and future conditions. The application on a case study highlights the capability of the tool to identify weak points of the urban drainage systems. Thereby it is possible to identify urban drainage system components which cause the highest performance decrease across the entire system. The application of the method on a real world case study shows for instance that a reduction of catchment areas which are located upstream of CSOs with relatively less capacity in the downstream sewers achieves the highest increases efficiency of the system. Finally, the application of VulNetUD is seen as a valuable tool for managers and operators of waste water utilities to improve the efficiency of their systems. Additionally vulnerability maps generated by VulNetUD support risk management e.g. decision making in urban development planning or the development of rehabilitation strategies.

  15. Scanning Electron Microscopic Features of the External and Internal Surfaces of Normal Adult Lacrimal Drainage System. (United States)

    Ali, Mohammad Javed; Baig, Farhana; Lakshman, Mekala; Naik, Milind N


    The aim of this study was to examine the ultrastructural features of the external and internal surfaces of healthy lacrimal drainage systems. A prospective interventional study was performed on the healthy adult lacrimal drainage systems obtained from fresh exenterated specimens. Exenteration was performed for malignancies unrelated to lacrimal system where preoperative lacrimal evaluation was normal. A careful and thorough dissection was carried out to isolate the entire lacrimal drainage system from the punctum to the nasolacrimal duct. The analysis was performed using the standard protocols of scanning electron microscopy. Inner punctal surfaces showed a definite and slightly elevated junction between the luminal surfaces of punctum and beginning of the vertical canaliculus. Similar junction could be identified between the lacrimal sac and nasolacrimal duct. The valves of the canaliculi showed broad rugae-like mucosal surfaces, whereas the external surfaces of the canaliculi demonstrated well-defined orbicularis muscle with collagenous attachments. The walls of the lacrimal sac and nasolacrimal duct showed dense vascular plexus which included wide luminal arteries, throttle veins, and large capacitance vessels. Ultrastructural features of external and internal surfaces of lacrimal drainage system help in better understanding of its anatomy and physiology. The junctional area between the punctum-vertical canaliculus and lacrimal sac-nasolacrimal duct needs further exploration to understand their roles.

  16. Staged cost optimization of urban storm drainage systems based on hydraulic performance in a changing environment

    Directory of Open Access Journals (Sweden)

    M. Maharjan


    Full Text Available Urban flooding causes large economic losses, property damage and loss of lives. The impact of environmental changes, mainly urbanization and climatic change, leads to increased runoff and peak flows which the drainage system must be able to cope with to reduce potential damage and inconvenience. Allowing for detention storage to compliment the conveyance capacity of the drainage system network is one of the approaches to reduce urban floods. Contemporary practice is to design systems against stationary environmental forcings – including design rainfall, landuse, etc. Due to the rapid change in the climate- and the urban environment, this approach is no longer appropriate, and explicit consideration of gradual changes during the life-time of the drainage system is warranted. In this paper, a staged cost optimization tool based on the hydraulic performance of the drainage system is presented. A one dimensional hydraulic model is used for hydraulic evaluation of the network together with a genetic algorithm based optimization tool to determine optimal intervention timings and responses over the analysis period. The model was applied in a case study area in the city of Porto Alegre, Brazil. It was concluded that considerable financial savings and/or additional level of flood-safety can be achieved by approaching the design problem as a staged plan rather than one-off scheme.

  17. Methodology of sensitive planning and design of stormwater drainage system on urban watersheds

    Directory of Open Access Journals (Sweden)

    Milićević Dragan B.


    Full Text Available For sustainable stormwater management planning in urban areas a hierarchical approach is needed, from planning on the watershed level, to the implementation on the location level, so a comprehensive approach to planning and designing the improvement of stormwater drainage could be provided with a goal of developing a drainage system, which balances the goals of drainage efficiency maximization and minimizing the negative effects on the environment. But the watershed level, which is relevant to urban hydrology, is almost always ignored while developing stormwater management plans. This paper shows a methodology oriented towards studying of the morphology of the urban watershed in the context of sustainable stormwater management, which consist of five steps and intends to help city planners and engineers choose the right location and make a selection of the best stormwater management practices when defining a sustainable decentralized stormwater management plan.

  18. Controlled Drainage As Measure to Reduce Nitrate Leaching in a Wheat Cropping System

    DEFF Research Database (Denmark)

    Børgesen, Christen Duus; Hvid, Søren Kolind; Thomsen, Ingrid Kaag


    Subsurface drainage of soil to avoid water logging is a prerequisite for crop cultivation for a large proportion of the agricultural land, and approximately 50% of the Danish agricultural area is artificially drained. Multifunctional drain systems can be effective measures to reduce losses...... of nutrients, such as Controlled Drainage (CD). With CD the water table of drained fields is raised or lowered by adjusting the drain pipe outlet elevation. By restricting drain flow at times when drainage is not needed, the overall volume of water flow is reduced, more soil moisture is available......, preserving ammonium for crop uptake in the following cropping season. Installed equipment, soil survey results and measurement results from the first winter season will be presented....

  19. Impacts of Climate Change on Rainfall Extremes and Urban Drainage Systems

    DEFF Research Database (Denmark)

    Willems, P.; Olsson, J.; Arnbjerg-Nielsen, Karsten

    Impacts of Climate Change on Rainfall Extremes and Urban Drainage Systems provides a state-of-the-art overview of existing methodologies and relevant results related to the assessment of the climate change impacts on urban rainfall extremes as well as on urban hydrology and hydraulics....... This overview focuses mainly on several difficulties and limitations regarding the current methods and discusses various issues and challenges facing the research community in dealing with the climate change impact assessment and adaptation for urban drainage infrastructure design and management....

  20. Use of Remote Sensing for Identification and Description of Subsurface Drainage System Condition

    Directory of Open Access Journals (Sweden)

    Lenka Tlapáková


    Full Text Available The paper presents basic facts and knowledge of special survey focused on detection and evaluation methods of subsurface drainage systems by means of remote sensing. It is aimed at the complex analysis of applied processes in spatial localization, classification or assessment of subsurface drainage systems’ actual condition by means of distance research methods. Data collection, their analysis and interpretation have been shown in seven experimental areas in the Czech Republic. Mainly it means determination of potential, application principles and limits of pracical use of different technologies and image data obtained by remote sensing in solving questions.

  1. A confined-unconfined aquifer model for subglacial hydrology (United States)

    Beyer, Sebastian; Kleiner, Thomas; Humbert, Angelika


    Modeling the evolution of subglacial channels underneath ice sheets is an urgent need for ice sheet modellers, as channels affect sliding velocities and hence ice discharge. Owing to very limited observations of the subglacial hydraulic system, the development of physical models is quite restricted. Subglacial hydrology models are currently taking two different approaches: either modeling the development of a network of individual channels or modeling an equivalent porous layer where the channels are not resolved individually but modeled as a diffusive process, adjusted to reproduce the characteristic of an efficient system. Here, we use the latter approach, improving it by using a confined-unconfined aquifer model (CUAS), that allows the system to run dry in absence of sufficient water input. This ensures physical values for the water pressure. Channels are represented by adjusting the permeability and storage of the system according to projected locations of channels. The evolution of channel positions is governed by a reduced complexity model that computes channel growths according to simple rules (weighted random walks descending the hydraulic potential). As a proof of concept we present the results of the evolution of the hydrological system over time for a simple artificial glacier geometry.

  2. Flow Forecasting in Drainage Systems with Extrapolated Radar Rainfall Data and Auto Calibration on Flow Observations

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Grum, M.; Rasmussen, Michael R.


    in a small urban catchment has been developed. The forecast is based on application of radar rainfall data, which by a correlation based technique, is extrapolated with a lead time up to two hours. The runoff forecast in the drainage system is based on a fully distributed MOUSE model which is auto...

  3. An initial experience with a digital drainage system during the postoperative period of pediatric thoracic surgery

    Directory of Open Access Journals (Sweden)

    Altair da Silva Costa Jr

    Full Text Available ABSTRACT Objective: To report an initial experience with a digital drainage system during the postoperative period of pediatric thoracic surgery. Methods: This was a prospective observational study involving consecutive patients, ≤ 14 years of age, treated at a pediatric thoracic surgery outpatient clinic, for whom pulmonary resection (lobectomy or segmentectomy via muscle-sparing thoracotomy was indicated. The parameters evaluated were air leak (as quantified with the digital system, biosafety, duration of drainage, length of hospital stay, and complications. The digital system was used in 11 children (mean age, 5.9 ± 3.3 years. The mean length of hospital stay was 4.9 ± 2.6 days, the mean duration of drainage was 2.5 ± 0.7 days, and the mean drainage volume was 270.4 ± 166.7 mL. The mean maximum air leak flow was 92.78 ± 95.83 mL/min (range, 18-338 mL/min. Two patients developed postoperative complications (atelectasis and pneumonia, respectively. The use of this digital system facilitated the decision-making process during the postoperative period, reducing the risk of errors in the interpretation and management of air leaks.

  4. Fractal dimension estimations of drainage network in the Carpathian-Pannonian system.

    NARCIS (Netherlands)

    Dombradi, E.; Timar, G.; Bada, G.; Cloetingh, S.A.P.L.; Horvath, F.


    The development of drainage network in the intra-Carpathian realm is influenced by a complex Quaternary tectonic evolution manifested with differential vertical motions. The present-day configuration of the left-hand side tributary system of the Tisza river was studied by means of fractal analysis.

  5. Past, present, and future design of urban drainage systems with focus on Danish experiences

    DEFF Research Database (Denmark)

    Arnbjerg-Nielsen, Karsten


    Climate change will influence the water cycle substantially, and extreme precipitation will become more frequent in many regions in the years to come. How should this fact be incorporated into design of urban drainage systems, if at all? And how important is climate change compared to other changes...

  6. A Water Hammer Protection Method for Mine Drainage System Based on Velocity Adjustment of Hydraulic Control Valve

    Directory of Open Access Journals (Sweden)

    Yanfei Kou


    Full Text Available Water hammer analysis is a fundamental work of pipeline systems design process for water distribution networks. The main characteristics for mine drainage system are the limited space and high cost of equipment and pipeline changing. In order to solve the protection problem of valve-closing water hammer for mine drainage system, a water hammer protection method for mine drainage system based on velocity adjustment of HCV (Hydraulic Control Valve is proposed in this paper. The mathematic model of water hammer fluctuations is established based on the characteristic line method. Then, boundary conditions of water hammer controlling for mine drainage system are determined and its simplex model is established. The optimization adjustment strategy is solved from the mathematic model of multistage valve-closing. Taking a mine drainage system as an example, compared results between simulations and experiments show that the proposed method and the optimized valve-closing strategy are effective.

  7. Subsurface drainage

    CSIR Research Space (South Africa)

    Van Der Merwe, CJ


    Full Text Available and long term behavior were evaluated. Laboratory tests for geotextile selection are recommended and tentative criteria given. The use of fin drains was evaluated in the laboratory and a field study to monitor the efficacy of drainage systems was started...

  8. Antarctic Subglacial Lake Classification Inventory, Version 1 (United States)

    National Aeronautics and Space Administration — This data set is an Antarctic radar-based subglacial lake classification collection, which focuses on the radar reflection properties of each given lake.

  9. [Application of Digital Drainage System in Postoperative Refractory Prolonged Air Leaks after Pulmonary Surgery]. (United States)

    Chen, Donglai; Kadeer, Xiermaimaiti; Shi, Zhe; Jin, Yuxing; Chen, Chang


    Postoperative prolonged air leaks is one of the most common complications secondary to pulmonary resections. Digital drainage system (DDS) is considered as an accurate and objective device which has been found to be comfortable and well tolerated by patients, economical as well. The aim of this study is to explore the application of DDS in patients with postoperative refractory prolonged air leaks after pulmonary surgery. Prolonged air leak (PAL) is defined as air leaks lasting for more than 5 d after video-assisted surgery or more than 7 d after thoracotomy. Postoperative refractory prolonged air leak is defined as a kind of air leak lasting for twice than PAL with grade 2 or 3 air leak, or air leak with severe complications such as subcutaneous or mediastinal emphysema in our study. A total of 8 patients who had postoperative refractory prolonged air leaks after pulmonary resection were treated with digital drainage system combined with pleurodesis from January to December in 2016 in Department of Thoracic Surgery, Shanghai Pulmonary Hospital. All the relevant clinical data of patients were collected for analysis. In our study, 6 patients accepted lobectomy, the other 2 patients underwent segmentectomy. The average air leak and chest tube duration of the patients with postoperative refractory prolonged air leaks after pulmonary resection was (17.3±5.1) d. The average postoperative DDS duration was (5.6±3.7) d. The mean drainage volume of the patients was (2,615.6±1,741.2) mL and (935.0±242.7) mL before and after the application of DDS. The average length of hospital stay was (18.1±5.0) d. It is safe and feasible to apply digital drainage system to patients with postoperative refractory prolonged air leaks after pulmonary resection. Compared with the conventional drainage system, digital drainage system is more accurate and objective which can offer a larger suction pressure and promote lung recruitment maneuver for pleurodesis, shortening the drainage time

  10. Clean hot water drilling for exploration of the Antarctic deep subglacial environment (United States)

    Makinson, K.; Pearce, D.; Hodgson, D.; Bentley, M.; Smith, A.; Tranter, M.; Rose, M. C.; Ross, N.; Mowlem, M. C.; Parnell, J.; Siegert, M. J.


    Overlain by several kilometres of ice, the subglacial environments deep beneath the Antarctic Ice Sheet are regarded as extreme habitats for microbial life and repositories of important paleoclimate records. Of significant scientific interest, yet remaining largely unexplored, accessing and sampling these environments presents several challenges to existing drilling technologies. With over half of the ice sheet believed to be resting on a wet bed, much of it part of a hydrological drainage network, accessing of this environment must conform to international environmental contamination protocols. This makes hot water drilling the most viable option for clean, fast, access through thick ice. After two decades of planning, involving the development of drilling techniques for subglacial access, instrument design and logistics set up, significant progress has been made in attempts to directly access, measure, and sample subglacial lakes and sediments. Combining the experiences from the notable setbacks and successes, as well as recent field testing for this drilling technique, the most practical technical options and operational procedures for future clean entry into Subglacial Lake Ellsworth and other deep (>3000 m) access targets will be presented.

  11. Nonlinear analysis of drainage systems to examine surface deformation: an example from Potwar Plateau (Northern Pakistan

    Directory of Open Access Journals (Sweden)

    F. Shahzad


    Full Text Available We devise a procedure in order to characterize the relative vulnerability of the Earth's surface to tectonic deformation using the geometrical characteristics of drainage systems. The present study focuses on the nonlinear analysis of drainage networks extracted from Digital Elevation Models in order to localize areas strongly influenced by tectonics. We test this approach on the Potwar Plateau in northern Pakistan. This area is regularly affected by damaging earthquakes. Conventional studies cannot pinpoint the zones at risk, as the whole region is characterized by a sparse and diffuse seismicity. Our approach is based on the fact that rivers tend to linearize under tectonic forcing. Thus, the low fractal dimensions of the Swan, Indus and Jehlum Rivers are attributed to neotectonic activity. A detailed textural analysis is carried out to investigate the linearization, heterogeneity and connectivity of the drainage patterns. These textural aspects are quantified using the fractal dimension, as well as lacunarity and succolarity analysis. These three methods are complimentary in nature, i.e. objects with similar fractal dimensions can be distinguished further with lacunarity and/or succolarity analysis. We generate maps of fractal dimensions, lacunarity and succolarity values using a sliding window of 2.5 arc minutes by 2.5 arc minutes (2.5'×2.5'. These maps are then interpreted in terms of land surface vulnerability to tectonics. This approach allowed us to localize several zones where the drainage system is highly structurally controlled on the Potwar Plateau. The region located between Muree and Muzaffarabad is found to be prone to destructive events whereas the area westward from the Indus seems relatively unaffected. We conclude that a nonlinear analysis of the drainage system is an efficient additional tool to locate areas likely to be affected by massive destructing events affecting the Earth's surface and therefore threaten human

  12. A global analysis approach for investigating structural resilience in urban drainage systems. (United States)

    Mugume, Seith N; Gomez, Diego E; Fu, Guangtao; Farmani, Raziyeh; Butler, David


    Building resilience in urban drainage systems requires consideration of a wide range of threats that contribute to urban flooding. Existing hydraulic reliability based approaches have focused on quantifying functional failure caused by extreme rainfall or increase in dry weather flows that lead to hydraulic overloading of the system. Such approaches however, do not fully explore the full system failure scenario space due to exclusion of crucial threats such as equipment malfunction, pipe collapse and blockage that can also lead to urban flooding. In this research, a new analytical approach based on global resilience analysis is investigated and applied to systematically evaluate the performance of an urban drainage system when subjected to a wide range of structural failure scenarios resulting from random cumulative link failure. Link failure envelopes, which represent the resulting loss of system functionality (impacts) are determined by computing the upper and lower limits of the simulation results for total flood volume (failure magnitude) and average flood duration (failure duration) at each link failure level. A new resilience index that combines the failure magnitude and duration into a single metric is applied to quantify system residual functionality at each considered link failure level. With this approach, resilience has been tested and characterised for an existing urban drainage system in Kampala city, Uganda. In addition, the effectiveness of potential adaptation strategies in enhancing its resilience to cumulative link failure has been tested. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Enhancing future resilience in urban drainage system: Green versus grey infrastructure. (United States)

    Dong, Xin; Guo, Hao; Zeng, Siyu


    In recent years, the concept transition from fail-safe to safe-to-fail makes the application of resilience analysis popular in urban drainage systems (UDSs) with various implications and quantifications. However, most existing definitions of UDSs resilience are confined to the severity of flooding, while uncertainties from climate change and urbanization are not considered. In this research, we take into account the functional variety, topological complexity, and disturbance randomness of UDSs and define a new formula of resilience based on three parts of system severity, i.e. social severity affected by urban flooding, environmental severity caused by sewer overflow, and technological severity considering the safe operation of downstream facilities. A case study in Kunming, China is designed to compare the effect of green and grey infrastructure strategies on the enhancement of system resilience together with their costs. Different system configurations with green roofs, permeable pavement and storage tanks are compared by scenario analysis with full consideration of future uncertainties induced by urbanization and climate change. The research contributes to the development of sustainability assessment of urban drainage system with consideration of the resilience of green and grey infrastructure under future change. Finding the response measures with high adaptation across a variety of future scenarios is crucial to establish sustainable urban drainage system in a long term. Copyright © 2017. Published by Elsevier Ltd.

  14. Comparison of short term rainfall forecasts for model based flow prediction in urban drainage systems

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Poulsen, Troels Sander; Bøvith, Thomas


    Forecast based flow prediction in drainage systems can be used to implement real time control of drainage systems. This study compares two different types of rainfall forecasts – a radar rainfall extrapolation based nowcast model and a numerical weather prediction model. The models are applied...... performance of the system is found using the radar nowcast for the short leadtimes and weather model for larger lead times....... as input to an urban runoff model predicting the inlet flow to a waste water treatment plant. The modelled flows are auto-calibrated against real time flow observations in order to certify the best possible forecast. Results show that it is possible to forecast flows with a lead time of 24 hours. The best...

  15. Comparison Of Short Term Rainfall Forecasts For Model Based Flow Prediction In Urban Drainage Systems

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Poulsen, Troels Sander; Bøvith, Thomas


    Forecast based flow prediction in drainage systems can be used to implement real time control of drainage systems. This study compares two different types of rainfall forecasts – a radar rainfall extrapolation based nowcast model and a numerical weather prediction model. The models are applied...... performance of the system is found using the radar nowcast for the short leadtimes and weather model for larger lead times....... as input to an urban runoff model predicting the inlet flow to a waste water treatment plant. The modelled flows are auto-calibrated against real time flow observations in order to certify the best possible forecast. Results show that it is possible to forecast flows with a lead time of 24 hours. The best...

  16. Balance Mass Flux and Velocity Across the Equilibrium Line in Ice Drainage Systems of Greenland (United States)

    Zwally, H. Jay; Giovinetto, Mario B.; Koblinsky, Chester J. (Technical Monitor)


    Estimates of balance mass flux and the depth-averaged ice velocity through the cross-section aligned with the equilibrium line are produced for each of six drainage systems in Greenland. (The equilibrium line, which lies at approximately 1200 m elevation on the ice sheet, is the boundary between the area of net snow accumulation at higher elevations and the areas of net melting at lower elevations around the ice sheet.) Ice drainage divides and six major drainage systems are delineated using surface topography from ERS (European Remote Sensing) radar altimeter data. The net accumulation rate in the accumulation zone bounded by the equilibrium line is 399 Gt/yr and net ablation rate in the remaining area is 231 Gt/yr. (1 GigaTon of ice is 1090 kM(exp 3). The mean balance mass flux and depth-averaged ice velocity at the cross-section aligned with the modeled equilibrium line are 0.1011 Gt kM(exp -2)/yr and 0.111 km/yr, respectively, with little variation in these values from system to system. The ratio of the ice mass above the equilibrium line to the rate of mass output implies an effective exchange time of approximately 6000 years for total mass exchange. The range of exchange times, from a low of 3 ka in the SE drainage system to 14 ka in the NE, suggests a rank as to which regions of the ice sheet may respond more rapidly to climate fluctuations.

  17. Surface water drainage system. Environmental assessment and finding of no significant impact

    Energy Technology Data Exchange (ETDEWEB)



    This Environmental Assessment (EA) is written pursuant to the National Environmental Policy Act (NEPA). The document identifies and evaluates the action proposed to correct deficiencies in, and then to maintain, the surface water drainage system serving the Department of Energy`s Rocky Flats Environmental Technology Site (Site), located north of Golden, Colorado. Many of the activities proposed would not normally be subject to this level of NEPA documentation. However, in many cases, maintenance of the system has been deferred to the point that wetlands vegetation has become established in some ditches and culverts, creating wetlands. The proposed activities would damage or remove some of these wetlands in order to return the drainage system to the point that it would be able to fully serve its intended function - stormwater control. The Department of Energy (DOE) regulations require that activities affecting environmentally sensitive areas like wetlands be the subject of an EA. Most portions of the surface water drainage system are presently inadequate to convey the runoff from a 100-year storm event. As a result, such an event would cause flooding across much of the Site and possibly threaten the integrity of the dams at the terminal ponds. Severe flooding would not only cause damage to facilities and equipment, but could also facilitate the transport of contaminants from individual hazardous substance sites (IHSSs). Uncontrolled flow through the A- and B-series ponds could cause contaminated sediments to become suspended and carried downstream. Additionally, high velocity flood flows significantly increase erosion losses.

  18. Integration of sustainable urban drainage systems into the design of neighbourhoods as a water rehabilitation action


    Reyes Vilariño, Marta; Calama Rodríguez, José María; Martín del Río, Juan Jesús; Mercader-Moyano, Pilar (Coordinador)


    The design of urban systems that allow the introduction of techniques for the recycling and drainage of rainwater represents a new aspect for the development of urban planning with sustainability criteria, since its main objectives include: the optimisation of the use of water as a resource in cities, the minimisation of the impacts on the natural cycle of water, and the protection of the ecosystem upon which it depends. Our proposal is based on the so-called water-sensitive ur...

  19. SSh versus TSE sequence protocol in rapid MR examination of pediatric patients with programmable drainage system. (United States)

    Brichtová, Eva; Šenkyřík, J


    A low radiation burden is essential during diagnostic procedures in pediatric patients due to their high tissue sensitivity. Using MR examination instead of the routinely used CT reduces the radiation exposure and the risk of adverse stochastic effects. Our retrospective study evaluated the possibility of using ultrafast single-shot (SSh) sequences and turbo spin echo (TSE) sequences in rapid MR brain imaging in pediatric patients with hydrocephalus and a programmable ventriculoperitoneal drainage system. SSh sequences seem to be suitable for examining pediatric patients due to the speed of using this technique, but significant susceptibility artifacts due to the programmable drainage valve degrade the image quality. Therefore, a rapid MR examination protocol based on TSE sequences, less sensitive to artifacts due to ferromagnetic components, has been developed. Of 61 pediatric patients who were examined using MR and the SSh sequence protocol, a group of 15 patients with hydrocephalus and a programmable drainage system also underwent TSE sequence MR imaging. The susceptibility artifact volume in both rapid MR protocols was evaluated using a semiautomatic volumetry system. A statistically significant decrease in the susceptibility artifact volume has been demonstrated in TSE sequence imaging in comparison with SSh sequences. Using TSE sequences reduced the influence of artifacts from the programmable valve, and the image quality in all cases was rated as excellent. In all patients, rapid MR examinations were performed without any need for intravenous sedation or general anesthesia. Our study results strongly suggest the superiority of the TSE sequence MR protocol compared to the SSh sequence protocol in pediatric patients with a programmable ventriculoperitoneal drainage system due to a significant reduction of susceptibility artifact volume. Both rapid sequence MR protocols provide quick and satisfactory brain imaging with no ionizing radiation and a reduced need

  20. Intelligent real-time operation of a pumping station for an urban drainage system (United States)

    Hsu, Nien-Sheng; Huang, Chien-Lin; Wei, Chih-Chiang


    SummaryIn this study, we apply artificial intelligence techniques to the development of two real-time pumping station operation models, namely, a historical and an optimized adaptive network-based fuzzy inference system (ANFIS-His and ANFIS-Opt, respectively). The functions of these two models are the determination of the real-time operation criteria of various pumping machines for controlling flood in an urban drainage system during periods when the drainage gate is closed. The ANFIS-His is constructed from an adaptive network-based fuzzy inference system (ANFIS) using historical operation records. The ANFIS-Opt is constructed from an ANFIS using the best operation series, which are optimized by a tabu search of historical flood events. We use the Chung-Kong drainage basin, New Taipei City, Taiwan, as the study area. The operational comparison variables are the highest water level (WL) and the absolute difference between the final WL and target WL of a pumping front-pool. The results show that the ANFIS-Opt is better than the ANFIS-His and historical operation models, based on the operation simulations of two flood events using the two operation models.

  1. Automatic detection of subglacial lakes in radar sounder data acquired in Antarctica (United States)

    Ilisei, Ana-Maria; Khodadadzadeh, Mahdi; Dalsasso, Emanuele; Bruzzone, Lorenzo


    Subglacial lakes decouple the ice sheet from the underlying bedrock, thus facilitating the sliding of the ice masses towards the borders of the continents, consequently raising the sea level. This motivated increasing attention in the detection of subglacial lakes. So far, about 70% of the total number of subglacial lakes in Antarctica have been detected by analysing radargrams acquired by radar sounder (RS) instruments. Although the amount of radargrams is expected to drastically increase, from both airborne and possible future Earth observation RS missions, currently the main approach to the detection of subglacial lakes in radargrams is by visual interpretation. This approach is subjective and extremely time consuming, thus difficult to apply to a large amount of radargrams. In order to address the limitations of the visual interpretation and to assist glaciologists in better understanding the relationship between the subglacial environment and the climate system, in this paper, we propose a technique for the automatic detection of subglacial lakes. The main contribution of the proposed technique is the extraction of features for discriminating between lake and non-lake basal interfaces. In particular, we propose the extraction of features that locally capture the topography of the basal interface, the shape and the correlation of the basal waveforms. Then, the extracted features are given as input to a supervised binary classifier based on Support Vector Machine to perform the automatic subglacial lake detection. The effectiveness of the proposed method is proven both quantitatively and qualitatively by applying it to a large dataset acquired in East Antarctica by the MultiChannel Coherent Radar Depth Sounder.

  2. Eustatic and tectonic change effects in the reversion of the transcontinental Amazon River drainage system

    Directory of Open Access Journals (Sweden)

    Mario Vicente Caputo

    Full Text Available ABSTRACT: The development of the transcontinental Amazon River System involved geological events in the Andes Chain; Vaupés, Purus and Gurupá arches; sedimentary basins of the region and sea level changes. The origin and age of this river have been discussed for decades, and many ideas have been proposed, including those pertaining to it having originated in the Holocene, Pleistocene, Pliocene, Late Miocene, or even earlier times. Under this context, the geology of the sedimentary basins of northern Brazil has been analyzed from the Mesozoic time on, and some clarifications are placed on its stratigraphy. Vaupés Arch, in Colombia, was uplifted together with the Andean Mountains in the Middle Miocene time. In the Cenozoic Era, the Purus Arch has not blocked this drainage system westward to marine basins of Western South America or eastward to the Atlantic Ocean. Also the Gurupá Arch remained high up to the end of Middle Miocene, directing this drainage system westward. With the late subsidence and breaching of the Gurupá Arch and a major fall in sea level, at the beginning of the Late Miocene, the Amazon River quickly opened its pathway to the west, from the Marajó Basin, through deep headward erosion, capturing a vast drainage network from cratonic and Andean areas, which had previously been diverted towards the Caribbean Sea. During this time, the large siliciclastic influx to the Amazon Mouth (Foz do Amazonas Basin and its fan increased, due to erosion of large tracts of South America, linking the Amazon drainage network to that of the Marajó Basin. This extensive exposure originated the Late Miocene (Tortonian unconformity, which marks the onset of the transcontinental Amazon River flowing into the Atlantic Ocean.

  3. The influence of Antarctic subglacial volcanism on the global iron cycle during the Last Glacial Maximum (United States)

    Frisia, Silvia; Weyrich, Laura S.; Hellstrom, John; Borsato, Andrea; Golledge, Nicholas R.; Anesio, Alexandre M.; Bajo, Petra; Drysdale, Russell N.; Augustinus, Paul C.; Rivard, Camille; Cooper, Alan


    Marine sediment records suggest that episodes of major atmospheric CO2 drawdown during the last glacial period were linked to iron (Fe) fertilization of subantarctic surface waters. The principal source of this Fe is thought to be dust transported from southern mid-latitude deserts. However, uncertainty exists over contributions to CO2 sequestration from complementary Fe sources, such as the Antarctic ice sheet, due to the difficulty of locating and interrogating suitable archives that have the potential to preserve such information. Here we present petrographic, geochemical and microbial DNA evidence preserved in precisely dated subglacial calcites from close to the East Antarctic Ice-Sheet margin, which together suggest that volcanically-induced drainage of Fe-rich waters during the Last Glacial Maximum could have reached the Southern Ocean. Our results support a significant contribution of Antarctic volcanism to subglacial transport and delivery of nutrients with implications on ocean productivity at peak glacial conditions.

  4. Adaption to Extreme Rainfall with Open Urban Drainage System: An Integrated Hydrological Cost-Benefit Analysis

    DEFF Research Database (Denmark)

    Zhou, Qianqian; Panduro, Toke Emil; Thorsen, Bo Jellesmark


    This paper presents a cross-disciplinary framework for assessment of climate change adaptation to increased precipitation extremes considering pluvial flood risk as well as additional environmental services provided by some of the adaptation options. The ability of adaptation alternatives to cope...... amenity effects, an integration of open drainage basins in urban recreational areas is likely the best adaptation strategy, followed by pipe enlargement and local infiltration strategies. All three were improvements compared to the fourth strategy of no measures taken........ The framework was applied to the northern part of the city of Aarhus, Denmark. We investigated four adaptation strategies that encompassed laissez-faire, larger sewer pipes, local infiltration units, and open drainage system in the urban green structure. We found that when taking into account environmental...

  5. Long forecast horizon to improve Real Time Control of urban drainage systems

    DEFF Research Database (Denmark)

    Courdent, Vianney Augustin Thomas; Vezzaro, Luca; Mikkelsen, Peter Steen


    on DORA’s approach, this study investigated the implementation of long forecast horizon using an ensemble forecast from a Numerical Weather Prediction (NWP) model. The uncertainty of the prediction is characterized by an ensemble of 25 forecast scenarios. According to the status of the UDS......) strategy was developed to operate Urban Drainage Systems (UDS) in order to minimize the expected overflow risk by considering the water volume presently stored in the drainage network, the expected runoff volume based on a 2-hours radar forecast model and an estimated uncertainty of the runoff forecast...... and the forecasted runoff volumes, the objectives for the control strategies might vary from optimization of water volumes to reduction of CSO risk. Thus different modes are implemented in DORA-LF (Long Forecast) in order to adjust the control strategies to the situations. In order to handle the long forecast...

  6. Using ensemble weather forecast in a risk based real time optimization of urban drainage systems

    DEFF Research Database (Denmark)

    Courdent, Vianney Augustin Thomas; Vezzaro, Luca; Mikkelsen, Peter Steen


    on DORA's approach, this study investigated the implementation of long forecast horizon using an ensemble forecast from a Numerical Weather Prediction (NWP) model. The uncertainty of the prediction is characterized by an ensemble of 25 forecast scenarios. According to the status of the UDS......) strategy was developed to operate Urban Drainage Systems (UDS) in order to minimize the expected overflow risk by considering the water volume presently stored in the drainage network, the expected runoff volume based on a 2-hours radar forecast model and an estimated uncertainty of the runoff forecast...... and the forecasted runoff volumes, the objectives for the control strategies might vary from optimization of water volumes to reduction of CSO risk. Thus different modes are implemented in DORA-LF (Long Forecast) in order to adjust the control strategies to the situations. In order to handle the long forecast...

  7. Feasibility of a simple drainage system in Cameroonian children after thoracotomy and decortication for empyema thoracis

    Directory of Open Access Journals (Sweden)

    Bernadette Ngo Nonga


    Full Text Available Background: To analyse the outcome of children with empyema thoracis treated by decortication followed by a simple drainage system. Patients and Methods: Retrospective chart review from July 2001 to June 2010 of all cases of children who had a thoracotomy for empyema. We used an endotracheal tube as chest drain and a urinary bag as a collector. Statistical analyses were done using EXCEL and SPSS 9.0. Results: Forty one children underwent thoracotomy and decortication for empyema, there were 23 boys and 18 girls with a sex ratio of 1, 21. The mean age was 2½ years with a minimum of 1 month and a maximum of 15 years of age; 27 children were below two years of age. All the patients have received antibiotic for a long period before surgery. The culture was negative, except in two cases where we found Klebsiella pneumonia and Staphylococcus aureus. In five cases, the empyema was due to Mycobacterium tuberculosis. Three children presented a complication: One child had a persistent purulent drainage for 2 weeks; another one was re-operated upon because of necrotic lung abscess and one child died of sepsis. In most cases, the chest tube was removed between day 4 and day 6 post-operatively. The average length of hospital stay after the surgery was 10 days. Conclusion: Thoracotomy and decortication in children with empyema can be safely done in Cameroon using a simple drainage system with good results compared to those in the literature.

  8. A generalised Dynamic Overflow Risk Assessment (DORA) for Real Time Control of urban drainage systems

    DEFF Research Database (Denmark)

    Vezzaro, Luca; Grum, Morten


    An innovative and generalised approach to the integrated Real Time Control of urban drainage systems is presented. The Dynamic Overflow Risk Assessment (DORA) strategy aims to minimise the expected Combined Sewer Overflow (CSO) risk by considering (i) the water volume presently stored in the drai......An innovative and generalised approach to the integrated Real Time Control of urban drainage systems is presented. The Dynamic Overflow Risk Assessment (DORA) strategy aims to minimise the expected Combined Sewer Overflow (CSO) risk by considering (i) the water volume presently stored...... in the drainage network, (ii) the expected runoff volume (calculated by radar-based nowcast models) and – most important – (iii) the estimated uncertainty of the runoff forecasts. The inclusion of uncertainty allows for a more confident use of Real Time Control (RTC). Overflow risk is calculated by a flexible...... periods, using a simple conceptual model, is presented. Compared to a traditional local control approach, DORA contributed to reduce CSO volumes from the most sensitive points while reducing total CSO volumes discharged from the catchment. Additionally, the results show that the inclusion of forecasts...

  9. Manual lymph drainage improving upper extremity edema and hand function in patients with systemic sclerosis in edematous phase

    National Research Council Canada - National Science Library

    Bongi, Susanna Maddali; Del Rosso, Angela; Passalacqua, Mauro; Miccio, Sara; Cerinic, Marco Matucci


    .... Manual lymph drainage (MLD) stimulates the lymphatic system and reduces edema. Our aim was to evaluate the efficacy of MLD in reducing edema and in improving functionality of the hands and perceived quality of life (QOL...

  10. Recent technical developments at the IMAU: A new generation of AWS and wireless subglacial measurements

    NARCIS (Netherlands)

    Smeets, C.J.P.P.; Boot, W.; van den Broeke, M.R.; van de Wal, R.S.W.


    Two technical developments are presented: a new generation of AWS and a wireless subglacial measurement system. Both systems build on the experience of the IMAU in developing GPS systems (Den Ouden et al., 2010). Combining methods to minimize energy consumption and wireless communication form the

  11. Reduction of acid rock drainage using steel slag in cover systems over sulfide rock waste piles. (United States)

    de Almeida, Rodrigo Pereira; Leite, Adilson do Lago; Borghetti Soares, Anderson


    The extraction of gold, coal, nickel, uranium, copper and other earth-moving activities almost always leads to environmental damage. In metal and coal extraction, exposure of sulfide minerals to the atmosphere leads to generation of acid rock drainage (ARD) and in underground mining to acid mine drainage (AMD) due to contamination of infiltrating groundwater. This study proposes to develop a reactive cover system that inhibits infiltration of oxygen and also releases alkalinity to increase the pH of generated ARD and attenuate metal contaminants at the same time. The reactive cover system is constructed using steel slag, a waste product generated from steel industries. This study shows that this type of cover system has the potential to reduce some of the adverse effects of sulfide mine waste disposal on land. Geochemical and geotechnical characterization tests were carried out. Different proportions of sulfide mine waste and steel slag were studied in leachate extraction tests. The best proportion was 33% of steel slag in dry weight. Other tests were conducted as follows: soil consolidation, saturated permeability and soil water characteristic curve. The cover system was numerically modeled through unsaturated flux analysis using Vadose/w. The solution proposed is an oxygen transport barrier that allows rain water percolation to treat the ARD in the waste rock pile. The results showed that the waste pile slope is an important factor and the cover system must have 5 m thickness to achieve an acceptable effectiveness. © The Author(s) 2015.

  12. Phylogeography of Buddleja crispa (Buddlejaceae) and its correlation with drainage system evolution in southwestern China. (United States)

    Yue, Liang-Liang; Chen, Gao; Sun, Wei-Bang; Sun, Hang


    Southwestern China is an area of active tectonism and erosion, yielding a dynamic, deeply eroded landscape that is hypothesized to have influenced the genetic structure of the resident populations of plants and animals. However, few studies have been conducted to examine the influence of changing river channels, particularly in the Yarlung Tsangpo area, on genetic distributions in plants. We here examine the population structure of Buddleja crispa, a dominant element of the dry, warm/hot river-valley communities, seeking to delimit the current population genetic structure and its relation to past changes in the courses of the major rivers in this area. • Two chloroplast DNA fragments were used to estimate the genetic variation and phylogeographic structure of the populations, and to infer nested clades, of the species. • We detected low intrapopulational haplotype diversity and higher overall population haplotype diversity (h(S) = 0.085, h(T) = 0.781). Molecular variance was mainly observed between groups (81.42%). Robust population genetic structure were detected by AMOVA (F(ST) = 0.967), coinciding with three nested clades (identified by NCPA) and five phylo-groups linked with paleo-drainage systems (identified by SAMOVA). No support for extensive spatial or demographical expansion was obtained. • A general pattern of genetic isolation by vicariance was inferred, and detected disjunct patterns strongly indicate that currently discontinuous drainage systems were historically linked. Most importantly, population subdivisions and genetic variation perfectly reflect the putative Paleo-Red-River drainage pattern, and Yarlung Tsangpo populations are closely related to Central Yunnan Plateau populations, indicating that they were previously connected by ancient river courses. Divergence times between these river systems estimated by molecular dating (in the Pleistocene) agree with previous findings.

  13. Regional reconstruction of subglacial hydrology and glaciodynamic behaviour along the southern margin of the Cordilleran Ice Sheet in British Columbia, Canada and northern Washington State, USA (United States)

    Lesemann, Jerome-Etienne; Brennand, Tracy A.


    Subglacial landsystems in and around Okanagan Valley, British Columbia, Canada are investigated in order to evaluate landscape development, subglacial hydrology and Cordilleran Ice Sheet dynamics along its southern margin. Major landscape elements include drumlin swarms and tunnel valleys. Drumlins are composed of bedrock, diamicton and glaciofluvial sediments; their form truncates the substrate. Tunnel valleys of various scales (km to 100s km length), incised into bedrock and sediment, exhibit convex longitudinal profiles, and truncate drumlin swarms. Okanagan Valley is the largest tunnel valley in the area and is eroded >300 m below sea level. Over 600 m of Late Wisconsin-age sediments, consisting of a fining-up sequence of cobble gravel, sand and silt fill Okanagan Valley. Landform-substrate relationships, landform associations, and sedimentary sequences are incompatible with prevailing explanations of landsystem development centred mainly on deforming beds. They are best explained by meltwater erosion and deposition during ice sheet underbursts. During the Late-Wisconsin glaciation, Okanagan Valley functioned as part of a subglacial lake spanning multiple connected valleys (few 100s km) of southern British Columbia. Subglacial lake development started either as glaciers advanced over a pre-existing sub-aerial lake (catch lake) or by incremental production and storage of basal meltwater. High geothermal heat flux, geothermal springs and/or subglacial volcanic eruptions contributed to ice melt, and may have triggered, along with priming from supraglacial lakes, subglacial lake drainage. During the underburst(s), sheetflows eroded drumlins in corridors and channelized flows eroded tunnel valleys. Progressive flow channelization focused flows toward major bedrock valleys. In Okanagan Valley, most of the pre-glacial and early-glacial sediment fill was removed. A fining-up sequence of boulder gravel and sand was deposited during waning stages of the underburst(s) and


    Directory of Open Access Journals (Sweden)

    G. I. Leychenkov


    Full Text Available In early February 2012, the drill hole at the Vostok Station encountered theLakeVostokwater. This step is important to study the lake composition including possible microbial life and to model subglacial environments however, the next ambitious target of the Vostok Drilling Project is sampling of bottom sediments, which contain the unique record of ice sheet evolution and environmental changes in centralAntarcticafor millions of years. In this connection, the forecast of sedimentary succession based on existing geophysical data, study of mineral inclusions in the accretion ice cores and tectonic models is important task. Interpretation of Airborne geophysical data suggests thatLakeVostokis the part of spacious rift system, which exists at least from Cretaceous. Reflection and refraction seismic experiments conducted in the southern part ofLakeVostokshow very thin (200–300 m stratified sedimentary cover overlying crystalline basement with velocity of 6.0–6.2 km/s. At present, deposition in southernLakeVostokis absent and similar conditions occurred likely at least last3 m.y. when ice sheet aboveLakeVostokchanged insignificantly. It can be also inferred that from the Late Miocene the rate of deposition inLakeVostokwas extremely low and so the most of sedimentary section is older being possibly of Oligocene to early to middle Miocene age when ice sheet oscillated and deposition was more vigorous. If so, the sampling of upper few meters of this condensed section is very informative in terms of history of Antarctic glaciation. Small thickness of sedimentary cover raises a question about existence of lake (rift depression during preglacial and early glacial times.

  15. Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation. (United States)

    Prudêncio, Maria Isabel; Valente, Teresa; Marques, Rosa; Sequeira Braga, Maria Amália; Pamplona, Jorge


    Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Subglacial Calcites from Northern Victoria Land: archive of Antarctic volcanism in the Last Glacial Maximum (United States)

    Frisia, Silvia; Weirich, Laura; Hellstrom, John; Borsato, Andrea; Golledge, Nicholas R.; Anesio, Alexandre M.; Bajo, Petra; Drysdale, Russell N.; Augustinus, Paul C.; Barbante, Carlo; Cooper, Alan


    Subglacial carbonates bear similarities to stalagmites in their fabrics and the potential to obtain precise chronologies using U-series methods. Their chemical properties also reflect those of their parent waters, which, in contrast to stalagmites, are those of subglacial meltwaters. In analogy to speleothems, stable Carbon isotope ratios and trace elements such as Uranium, Iron and Manganese provide the opportunity to investigate ancient extreme environments without the need to drill through thousands of metres of ice. Sedimentological, geochemical and microbial evidence preserved in LGM subglacial calcites from Northern Victoria Land, close to the East Antarctic Ice Sheet margin, allow us to infer that subglacial volcanism was active in the Trans Antarctic Mountain region and induced basal ice melting. We hypothesize that a meltwater reservoir was drained and injected into interconnected basal pore systems where microbial processes enhanced bedrock weathering and, thus, released micronutrients. Volcanic influence is supported by the presence of fluorine (F) and sulphur in sediment-laden calcite layers containing termophilic species. Notably, calcite δ13C points to dissolved inorganic carbon evolved from subglacial metabolic processes. Once transported to the sea, soluble iron likely contributed to fertilizing the Southern Ocean and CO2 drawdown. This is the first well-dated evidence for LGM volcanism in Antarctica, which complements the record of volcanic eruptions retrieved from Talos Dome ice core, and supports the hypothesis of large-scale volcanism as an important driver of climate change. We conclude that subglacial carbonates are equivalent to speleothems in their palaeoclimate potential and may become a most useful source of information of ecosystems and processes at peak glacials in high altitude/high latitude settings.

  17. Bacterial phylogenetic diversity in a constructed wetland system treating acid coal mine drainage

    Energy Technology Data Exchange (ETDEWEB)

    Nicorarat, D.; Dick, W.A.; Dopson, M.; Tuovinen, O.H. [Ohio State University, Columbus, OH (USA)


    Microorganisms in acid mine drainage are typically acidophiles that mediate the oxidation of reduced compounds of iron and sulfur. However, microbial populations in wetland systems constructed to treat acid mine drainage are not well characterized. This study was to analyze bacterial diversity, using cultivation-independent molecular ecological techniques, in a constructed wetland that received acid drainage from an abandoned underground coal mine. DNA was purified from Fe(III)-precipitates from the oxidized surface zone of wetland sediments and 16S rRNA gene sequences were amplified and cloned. A total of 200 clones were analyzed by restriction fragment length polymorphism (RFLP) and 77 unique RFLP patterns were obtained with four restriction enzymes. Of these patterns, 30 most dominant unique clones were selected for sequencing of their 16S rRNA genes. Half of these 30 clones could be matched with autotrophic iron- and sulfur-oxidizing bacteria (Acidithiohacillus ferrooxidans and Acidithiobacillus thiooxidans). Several clones also formed a clade with heterotrophic iron-oxidizing bacteria (TRA2-10, TRA3-20, and TRA5-3) and heterotrophic bacteria (Stenotrophomas maltophilia, Bordetella spp., Alcalgenes sp., Alcaligenesfaecalis, and Alcaligenes xylosoxidans). Approximately 40% and 35% of the analyzed RFLP restriction patterns were consistent with A. ferrooxidans and A. thiooxidans, respectively. The relatively high frequency of acidithiobacilli is consistent with the chemical and physical characteristics of this site i.e., continuous, abundant supply of reduced iron and sulfur compounds, pH 3-4, ambient temperature, and limited organics originating from the coal seam and from vegetation or soil surrounding the inlet channel to the wetland.

  18. Case study of fault survey based on drainage system analysis in Uljin area of Korean Peninsula (United States)

    Choi, Sung-Ja; Han, Jong-kyu


    DEM (Digital Elevation Model) produced by digital topographic map and satellite image have been utilized for geologic survey. This study aims to clarify the relationship between a knickpoint and faults in Namdae stream by the analysis of the digital elevation model. Namdae drainage basin is divided into three subbasins of S1, S2 and S3 of which knickpoints extracted from the digital elevation model developed on the middle to mid-upper region of the subbasins. Relative steepness Ks depending on deepening rate and concavity θ of basins is higher in S1 region than S2 and S3 regions. I assume the deepening rate caused by active erosion is resulted from the several faults crossing the basins rather than difference of rock types. The knickpoint of the NamDae drainage area which included low-ranking branch is all 77, 24 of which are on the main river system S1, S2, S3. 27 of 77 knickpoints are matched the faults (38%), and 13 knickpoints from three basins corresponds with the faults (54%). It indicates the knickpoints on the basins are closely connected with the faults. For example, relative steepness Ksn is 38.8 on average, but is 42.99 ~ 43.39 in the overlapping area of Samdang and Duchun faults , even considering the elevation above sea level. We suggest the faults cause the knickpoint of high Ksn like as a geomorphic deformation. As comparing the knickpoints and rock boundaries, there are little evidence of relationship between them, while 54 % of the knickpoints distribute on the subbasins S1, S2, and S3. We conclude the knickpoints of a drainage basin the fault movement results in are one of the geomorphological deformations and useful for survey of the Quaternary faults or for extension of the faults.

  19. Secondary reconstruction of severe contracted eye socket using modified ocular conformer-drainage tube system. (United States)

    Li, Jin; Lin, Ming; Ge, Shengfang; Fan, Xianqun


    Eye socket reconstruction has been previously reported; however, few reports address reconstruction in cases of socket contracture after graft failure. This is a retrospective observational case study of 42 patients who had previously undergone eye socket reconstruction after posttraumatic enucleation owing to severe thermal or chemical injury, and each of whom presented with a severe contracted eye socket. Patients underwent free skin grafts and the placement of a modified ocular conformer-drainage tube system. Eye sockets of adequate size were created in the 42 patients. Three patients presented with gradual extrusion of the eye prosthesis due to recurrent contraction of the inferior fornix after treatment. These patients agreed to further operative procedures 6 months after secondary reconstruction surgery, which resulted in mild upward tilting of the eye prosthesis without extrusion. The prosthetic eyes fit well in all of the secondary reconstructed sockets using this technique. Our studies suggest that the modified ocular conformer-drainage tube system can efficiently control infection after secondary reconstruction of the posttraumatic contracted socket and may result in less shrinkage of skin grafts.

  20. Generalization of the Sitnica river drainage system with potential pollution of tributaries

    Directory of Open Access Journals (Sweden)

    Valjarević Aleksandar


    Full Text Available Maps are miniature graphic representation of distinct area and as not being completely real require generalization. Cartographic generalization represents a specific investigation method in cartography. Generalization includes the processes of selection, simplification, and symbolization of details according to the purpose and the map scale. The river generalization requires the phase classification, selection, magnification and simplification to being used. Linear symbols are given on the map by their corresponding/characteristic length and remained unchanged even after the generalization. Particular cartographic criterions need to be applied during generalization. In the given case of the Sitnica river drainage system were applied the computer supported generalization based on the software Global Mapper 16.1 and the Open source software QGIS 2.6.1. The Sitnica drainage system is generalized in three levels. The first included digitalization of all linear objects related to the river Sitnica and its tributaries. Second level resulted in vector generalized data that indicate on polluted tributaries, whereas the final, third stage led to construction of multilayered vector map of the Sitnica catchments area with polluted tributaries.

  1. Structural control of englacial drainage systems in Himalayan debris-covered glaciers (United States)

    Gulley, J.; Benn, D. I.

    Englacial cave systems were mapped using speleological techniques in three debris-covered glaciers in the Khumbu Himal, Nepal. Detailed three-dimensional mapping of the cave systems and observations of relationships with structures in the surrounding ice show conduits formed by a mechanism directly analogous to speleogenesis in limestone karst. The highest, oldest parts of all passages developed along debris-filled crevasse traces with hydraulic conductivity in the range 10-4 to 10-5 m s-1. Conduits form when these hydraulically efficient pathways bridge between areas with different hydraulic potential. They then evolve by grading (through head-ward migration of nick points and vertical incision) to local base level, often the surface of supraglacial lakes. Most supraglacial lakes on Himalayan glaciers are perched above the elevation of the terminal stream, and exist for a few years before draining through englacial conduits. As a result, near-surface drainage evolution is frequently interrupted by base-level fall, and conduits may record multiple phases of incision. Conduits commonly migrate laterally during incision, undermining higher levels of the ice and encouraging collapse. Voids can be created by fluvial processes and collapse of crevassed ice. The oft-noted resemblance of the surface morphology of debris-covered glaciers to karst landscapes thus extends to the subsurface, and karst hydrology provides a framework for understanding englacial drainage.


    Energy Technology Data Exchange (ETDEWEB)

    J.B. Case


    The drainage of water from the emplacement drift is essential for the performance of the EBS. The unsaturated flow properties of the surrounding rock matrix and fractures determine how well the water will be naturally drained. To enhance natural drainage, it may be necessary to introduce engineered drainage features (e.g. drilled holes in the drifts), that will ensure communication of the flow into the fracture system. The purpose of the Water Drainage Model is to quantify and evaluate the capability of the drift to remove water naturally, using the selected conceptual repository design as a basis (CRWMS M&O, 1999d). The analysis will provide input to the Water Distribution and Removal Model of the EBS. The model is intended to be used to provide postclosure analysis of temperatures and drainage from the EBS. It has been determined that drainage from the EBS is a factor important to the postclosure safety case.

  3. Plio-Pleistocene evolution of the north Alpine drainage system: new constraints from detrital thermochronology of foreland deposits (United States)

    Reiter, Wolfgang; Elfert, Simon; Glotzbach, Christoph; Spiegel, Cornelia


    The evolution of drainage systems in and around active orogens may be strongly affected by climatic or tectonic processes. Information on the drainage evolution is stored in the sediments of the foreland depocentres. We investigated the provenance of two key deposits adjacent to the Central Alps, the Pliocene Sundgau gravels and the Pleistocene Höhere Deckenschotter by applying detrital thermochronology. Combined with provenance information from Rhine Graben deposits, we propose a reconstruction of the north Alpine drainage system since the middle Pliocene and discuss potential controlling mechanisms. Our data show that the Rhine Graben received detritus from the Alpine realm already during the Pliocene, indicating two different river systems—the proto-Rhine and the Aare-Doubs—draining the Alpine realm toward the North Sea and Mediterranean Sea. The investigated sediments contain detritus from two central Alpine sources, one showing a regional exhumational equilibrium and the other characterized by increasing exhumation rates. Discharge of the latter source ceased after ~2 Ma, reflecting a northward shift of the main Alpine drainage divide. Between ~2.0 and 1.2 Ma, the drainage system was affected by a major change, which we explain as resulting from a change in the Alpine stress field leading to tectonic exhumation and topography reduction in the area of the southern Aar massif. Generally, it seems that between ~4 and 1.2 Ma, the drainage system was mainly controlled by tectonic processes, despite first glaciations that already affected the north-Alpine foreland by ~2 Ma. The drainage system only seems to have reacted to the late Cenozoic climate changes after ~1.2 Ma, i.e., at the time of the most intense Alpine glaciation. At that time, the course of the Rhine River shifted toward the area of the Hegau volcanics, and the size of the Rhine River catchment became strongly reduced.

  4. Digital reconstruction of the Song Dynasty Ganzhou drainage system based on AR technology and its’ application in the new urban area planning and revision (United States)

    Cao, H. L.; Chen, Y. L.; Tao, T. H.


    Water-logging problem is a common problem in modern city. The urban built-up area of Zhangjiang new district in Ganzhou has the same water-logging problem, however, the old urban area of Ganzhou was praised as “Millennium no flood”. The drainage system of the old urban area of Ganzhou—Fushougou, which is not flooded for hundreds years because of the perfect drainage system. It’s valuable to be referenced to the modern city drainage and waterproof comprehensive planning. In order to explore the mystery of “Millennium no flood” of old urban area of Ganzhou, at the same time to provide directive opinion to the sustainability of Zhangjiang new urban area drainage system, this paper attempts to digital reconstruct the drainage system in old urban area of Ganzhou by augmented reality(AR). It will provide a new technological means and ways to evaluate the sustainability of urban underground drainage system under the surface feature changes in the landscape. On the basis of digital reconstruction of the drainage system in the old urban area of Ganzhou, the sustainability evaluation index of drainage system is studied by analyzing and contrasting with Zhangjiang new urban area drainage system, to guide the revision of comprehensive planning about city drainage and water-logging in the new urban area of Zhangjiang.

  5. Physiological ecology of microorganisms in Subglacial Lake Whillans

    Directory of Open Access Journals (Sweden)

    Trista J Vick-Majors


    Full Text Available Subglacial microbial habitats are widespread in glaciated regions of our planet. Some of these environments have been isolated from the atmosphere and from sunlight for many thousands of years. Consequently, ecosystem processes must rely on energy gained from the oxidation of inorganic substrates or detrital organic matter. Subglacial Lake Whillans (SLW is one of more than 400 subglacial lakes known to exist under the Antarctic ice sheet; however, little is known about microbial physiology and energetics in these systems. When it was sampled through its 800 m thick ice cover in 2013, the SLW water column was shallow (~2 m deep, oxygenated, and possessed sufficient concentrations of C, N, and P substrates to support microbial growth. Here, we use a combination of physiological assays and models to assess the energetics of microbial life in SLW. In general, SLW microorganisms grew slowly in this energy-limited environment. Heterotrophic cellular carbon turnover times, calculated from 3H-thymidine and 3H-leucine incorporation rates, were long (60 to 500 days while cellular doubling times averaged 196 days. Inferred growth rates (average ~0.006 d-1 obtained from the same incubations were at least an order of magnitude lower than those measured in Antarctic surface lakes and oligotrophic areas of the ocean. Low growth efficiency (8% indicated that heterotrophic populations in SLW partition a majority of their carbon demand to cellular maintenance rather than growth. Chemoautotrophic CO2-fixation exceeded heterotrophic organic C-demand by a factor of ~1.5. Aerobic respiratory activity associated with heterotrophic and chemoautotrophic metabolism surpassed the estimated supply of oxygen to SLW, implying that microbial activity could deplete the oxygenated waters, resulting in anoxia. We used thermodynamic calculations to examine the biogeochemical and energetic consequences of environmentally imposed switching between aerobic and anaerobic metabolisms

  6. Physiological Ecology of Microorganisms in Subglacial Lake Whillans (United States)

    Vick-Majors, Trista J.; Mitchell, Andrew C.; Achberger, Amanda M.; Christner, Brent C.; Dore, John E.; Michaud, Alexander B.; Mikucki, Jill A.; Purcell, Alicia M.; Skidmore, Mark L.; Priscu, John C.


    Subglacial microbial habitats are widespread in glaciated regions of our planet. Some of these environments have been isolated from the atmosphere and from sunlight for many thousands of years. Consequently, ecosystem processes must rely on energy gained from the oxidation of inorganic substrates or detrital organic matter. Subglacial Lake Whillans (SLW) is one of more than 400 subglacial lakes known to exist under the Antarctic ice sheet; however, little is known about microbial physiology and energetics in these systems. When it was sampled through its 800 m thick ice cover in 2013, the SLW water column was shallow (~2 m deep), oxygenated, and possessed sufficient concentrations of C, N, and P substrates to support microbial growth. Here, we use a combination of physiological assays and models to assess the energetics of microbial life in SLW. In general, SLW microorganisms grew slowly in this energy-limited environment. Heterotrophic cellular carbon turnover times, calculated from 3H-thymidine and 3H-leucine incorporation rates, were long (60 to 500 days) while cellular doubling times averaged 196 days. Inferred growth rates (average ~0.006 d−1) obtained from the same incubations were at least an order of magnitude lower than those measured in Antarctic surface lakes and oligotrophic areas of the ocean. Low growth efficiency (8%) indicated that heterotrophic populations in SLW partition a majority of their carbon demand to cellular maintenance rather than growth. Chemoautotrophic CO2-fixation exceeded heterotrophic organic C-demand by a factor of ~1.5. Aerobic respiratory activity associated with heterotrophic and chemoautotrophic metabolism surpassed the estimated supply of oxygen to SLW, implying that microbial activity could deplete the oxygenated waters, resulting in anoxia. We used thermodynamic calculations to examine the biogeochemical and energetic consequences of environmentally imposed switching between aerobic and anaerobic metabolisms in the SLW

  7. Study of hydraulic properties of binary beads mixture as porous media in sustainable urban drainage system (United States)

    Abdullah, Muhammad Faiz; Puay, How Tion; Zakaria, Nor Azazi


    Sustainable Urban Drainage System (SuDS) such as swales and rain gardens is showing growing popularity as a green technology for stormwater management and it can be used in all types of development to provide a natural approach to managing drainage. Soil permeability is a critical factor in selecting the right SuDS technique for a site. On this basis, we have set up a laboratory experiment to investigate the porosity and saturated hydraulic conductivity of single size and binary (two sizes) mixture using column-test as a preliminary investigation with two sets of glass beads with different sizes are used in this study. The porosity and saturated hydraulic conductivity for varies volume fraction of the course and fine glass beads were measured. It was found that the porosity of the binary mixture does not increase with the increment of the ratio of coarse to fine beads until the volume fraction of fine particles is equal to the coarse component. Saturated hydraulic conductivity result shows that the assumption of random packing was not achieved at the higher coarse ratio where most of the fine particles tend to sit at the bottom of the column forming separate layers which lower the overall hydraulic conductivity value.

  8. The Circle Nephrostomy Tube: An Attractive Nephrostomy Drainage System Following Complex Percutaneous Nephrolithotomy. (United States)

    El Tayeb, Marawan M; Borofsky, Michael S; Lingeman, James E


    To describe our experience with the circle nephrostomy tube (NT) (Cook Medical), a drainage system uniquely designed for use after multiple-access percutaneous nephrolithotomy (PNL). A retrospective review of 1317 consecutive patients undergoing 1599 PNLs at IU Health Methodist Hospital was performed. All multiple access cases utilizing circle NTs were reviewed and analyzed. The method of insertion of circle NT was demonstrated. A total of 1843 accesses were obtained in 1599 renal units (RUs): 380 upper pole, 129 interpolar, and 1334 lower pole. Multiple accesses in this series were required in 282 RUs (17.6%). Following multiple-access PNL, circle NTs, Cope loop, and reentry Malecot NTs were inserted in 91 RUs (32.3%), 208 RUs (73.8%), and 31 RUs (11%), respectively. None of the patients who had circle NT experienced clogging, dislodgement, or obstruction of the tube. The cost of circle, Cope loop, and Malecot NTs are 121.73 USD, 95.20 USD, and 81 USD, respectively. Circle NTs are easy to insert, secure, cost-effective compared with inserting two NTs. Circle NTs provide excellent drainage and facilitate secondary procedures. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Pathways and transit time of meltwater in the englacial drainage system of Rabots Glacier, Kebnekaise, Sweden (United States)

    Coch, Caroline; Clason, Caroline; Rosqvist, Gunhild; Jarsjö, Jerker; Brugger, Keith


    Following the crash of a Norwegian Hercules plane in the Kebnekaise mountain range in March 2012, a field campaign was initiated in order to assess the fate of the hydrocarbon pollution in the glacial system. Monitoring of pollution was conducted in the snow pack of Rabots glacier, as well as in the proglacial stream, and the preferential pathways for transport of pollutants were assessed. Since it is likely that soluble components of the aircraft fuel are transported within the glacial meltwater, our study focuses on constraining the likely transit time and dispersion of these components. The hydrologic configuration of Rabots glacier was thus studied during the 2013 ablation season by means of dye tracing experiments and discharge monitoring in the proglacial stream. The analyses of the dye return curves and stream monitoring suggest different hydrological configurations on the north and south side of the glacier, perhaps influenced by shading and the ice thermal structure. The system on the north side seems to be distributed, with extensive interaction of meltwater with the bed, as typified in the turbid proglacial outlet. The distinct peaks of the return curves on the south side indicate efficient transport, perhaps largely through englacial channels, given the relatively clear nature of the proglacial outlet. The evaluation of transit speed along a longitudinal profile contributed to the understanding of drainage efficiency with distance upglacier. The higher up the injection location on the glacier, the more distributed and less efficient the system. The seasonal evolution of efficiency was also assessed, showing an increase inefficiency with time. Furthermore, we hypothesize a disconnect in the glacial hydrological systems on the north and south side of the glacier. Pollution that is transported with the meltwater down from the crash site on the southern side most likely does not reach the drainage system on the northern side. Besides revealing potential

  10. Penicillium mycobiota in Arctic subglacial ice

    DEFF Research Database (Denmark)

    Sonjak, S.; Frisvad, Jens Christian; Gunde-Cimerman, N.


    to be inhabited exclusively by heterotrophic bacteria. In this study we report on the very high occurrence (up to 9000 CFU L-1) and diversity of filamentous Penicillium spp. in the sediment-rich subglacial ice of three different polythermal Arctic glaciers (Svalbard, Norway). The dominant species was P. crustosum......, representing on the average half of all isolated strains from all three glaciers. The other most frequently isolated species were P. bialowiezense, P. chrysogenum, P. thomii, P. solitum, P. palitans, P. echinulatum, P. polonicum, P. commune, P. discolor, P. expansum, and new Penicillium species (sp. 1). Twelve...... more Penicillium species were occasionally isolated. The fungi isolated produced consistent profiles of secondary metabolites, not different from the same Penicillium species from other habitats. This is the first report on the presence of large populations of Penicillium spp. in subglacial sediment...

  11. Numerical Modeling of Subglacial Sediment Deformation

    DEFF Research Database (Denmark)

    Damsgaard, Anders


    may cause mass loss in the near future to exceed current best estimates. Ice flow in larger ice sheets focuses in fast-moving streams due to mechanical non-linearity of ice. These ice streams often move at velocities several magnitudes larger than surrounding ice and consequentially constitute...... glaciers move by deforming their sedimentary beds. Several modern ice streams, in particular, move as plug flows due to basal sediment deformation. An intense and long-winded discussion about the appropriate description for subglacial sediment mechanics followed this discovery, with good reason...... velocities previously associated with elastic or viscous ice deformation. If a glacier dominated by subglacial creep experiences prolonged events of strong surface melt or increased driving stresses, the plastic strength limit can cause rapid acceleration downslope due to imbalance of stresses....

  12. Land use change in the Veneto floodplain and consequences on minor network drainage system

    Directory of Open Access Journals (Sweden)

    Massimo Prosdocimi


    Full Text Available Anthropic pressure has been proven to be one of the most evident forces able to alter landscapes. Its impact on the surroundings can be easily detectable especially in a high-density populated country such as Italy. Among the most evident anthropic alterations, the most important are the urbanization processes but also changes in cultural techniques that have been occurring in rural areas. These modifications influence the hydrologic regimes in two ways: by modifying the direct runoff production and by having a strong impact on the drainage system itself. The main objectives of this work are to evaluate the impact of land cover changes in the Veneto region (north-east Italy on the minor drainage network system, and to analyze changes in the direct runoff in the last 50 years. The study area is a typical agrarian landscape and it has been chosen considering its involvement in the major flood of 2010 and considering also the availability of data, including historical aerial photographs, historical information, and a high resolution LiDAR DTM. The results underline how land cover variations over the last 50 years have strongly increased the propension of the soil to produce direct runoff (increase of the Curve Number value and they have also reduced the extent of the minor network system to the detriment of urbanized areas and changes of plots of land boundaries. As a consequence, the capacity of the minor network to attenuate and eventually laminate a flood event is decreased as well. These analysis can be considered useful tools for a suitable land use planning in flood prone areas.

  13. Behaviour of oxamyl and propamocarb in two rockwool cultivation systems: open drainage and recirculation of nutrient solution excess

    NARCIS (Netherlands)

    Dekker, A.; Houx, N.W.H.; Runia, W.T.


    The behaviour of oxamyl and propamocarb was studied in nutrient solution applied at different rates to an open drainage system and a closed cultivation system for eighteen days. Hardly did any transformation occur in the nutrient solution in the supply tank. In periods of intense radiation the

  14. Hydrodynamic model of cells for designing systems of urban groundwater drainage (United States)

    Zimmermann, Eric; Riccardi, Gerardo


    An improved mathematical hydrodynamic quasi-two-dimensional model of cells, CELSUB3, is presented for simulating drainage systems that consist of pumping well fields or subsurface drains. The CELSUB3 model is composed of an assemblage of algorithms that have been developed and tested previously and that simulate saturated flow in porous media, closed conduit flow, and flow through pumping stations. A new type of link between aquifer cells and drainage conduits is proposed. This link is verified in simple problems with well known analytical solutions. The correlation between results from analytical and mathematical solutions was considered satisfactory in all cases. To simulate more complex situations, the new proposed version, CELSUB3, was applied in a project designed to control the water-table level within a sewer system in Chañar Ladeado Town, Santa Fe Province, Argentina. Alternative drainage designs, which were evaluated under conditions of dynamic recharge caused by rainfall in a critical year (wettest year for the period of record) and a typical year, are briefly described. After analyzing ten alternative designs, the best technical-economic solution is a subsurface drainage system of closed conduits with pumping stations and evacuation channels. Résumé. Un modèle hydrodynamique perfectionné de cellules en quasi 2D, CELSUB3, est présenté dans le but de simuler des systèmes de drainage qui consistent en des champs de puits de pompage ou de drains souterrains. Le modèle CELSUB3 est composé d'un assemblage d'algorithmes développés et testés précédemment et qui simulent des écoulements en milieu poreux saturé, en conduites et dans des stations de pompage. Un nouveau type de lien entre des cellules d'aquifères et des drains est proposé. Ce lien est vérifié dans des problèmes simples dont les solutions analytiques sont bien connues. La corrélation entre les résultats des solutions analytiques et des solutions mathématiques a été consid

  15. Simulating the arrangement of subsystem to reduce inundation in the drainage system of Pepelegi housing area Sidoarjo (United States)

    Brouwer, Steven; Wardoyo, Wasis; Lasminto, Umboro


    Pepelegi Indah Resident is a place which is frequently inundated by floodwater. This condition happened since the drainage system was designed with inappropriate waterflow method. The concern of this research was to figure out alternatives by managing the floodwater from the disposal drainage system. The existing information showed the area would be inundated if rainfall occurred for 2-3 hours. Half of Pepelegi Indah Resident would be inundated and subsidence time of flood on vulnerable time was 5-24 hours. To reduce the floodwater, some scenarios or simulations were carried out among others the management of tertiary drainage, the pool accommodation, and the provision of pumps at the enable point. From the simulation, the researcher should choose the best scenario which worked and optimally reduce the flooding. Based on the simulation results, the best scenario is the pool accommodation with new pumps at the primary channel.

  16. Study of diffuse source pollution management for land use and drainage system planning. (United States)

    Yamada, K; Funaki, T; Honda, S; Sugihara, M


    This study aims to clarify the mass balance of pollutants during both dry periods and storm events and to discuss the effects of some strategies such as pollutant removal, land use planning and new drainage systems by simulation. Three subjects are discussed in this paper. First, the amount of pollutants entering Lake Biwa from an urban area have been roughly estimated by using data collected by the local government. Second, many additional samples were collected from road surfaces, house roofs and parking lots to consider the role of land use in pollutant runoff. Third, some ongoing BMP projects in an urban area are introduced. As a result, some ideas on how to solve the problem of diffuse pollution in urban areas have been obtained.

  17. An initial experience with a digital drainage system during the postoperative period of pediatric thoracic surgery. (United States)

    Costa, Altair da Silva; Bachichi, Thiago; Holanda, Caio; Rizzo, Luiz Augusto Lucas Martins De


    To report an initial experience with a digital drainage system during the postoperative period of pediatric thoracic surgery. This was a prospective observational study involving consecutive patients, ≤ 14 years of age, treated at a pediatric thoracic surgery outpatient clinic, for whom pulmonary resection (lobectomy or segmentectomy via muscle-sparing thoracotomy) was indicated. The parameters evaluated were air leak (as quantified with the digital system), biosafety, duration of drainage, length of hospital stay, and complications. The digital system was used in 11 children (mean age, 5.9 ± 3.3 years). The mean length of hospital stay was 4.9 ± 2.6 days, the mean duration of drainage was 2.5 ± 0.7 days, and the mean drainage volume was 270.4 ± 166.7 mL. The mean maximum air leak flow was 92.78 ± 95.83 mL/min (range, 18-338 mL/min). Two patients developed postoperative complications (atelectasis and pneumonia, respectively). The use of this digital system facilitated the decision-making process during the postoperative period, reducing the risk of errors in the interpretation and management of air leaks. Relatar a experiência inicial com um sistema de drenagem digital no pós-operatório de cirurgia torácica pediátrica. Estudo observacional e prospectivo envolvendo pacientes consecutivos do ambulatório de cirurgia torácica pediátrica da instituição, com idade até 14 anos, e com indicação de ressecção pulmonar (lobectomia e/ou segmentectomia através de toracotomia poupadora muscular). Os parâmetros avaliados foram perda aérea (quantificada com o sistema digital), biossegurança, tempo de drenagem, tempo de internação e complicações. O sistema digital foi utilizado em 11 crianças, com média de idade de 5,9 ± 3,3 anos. A média do tempo de internação foi de 4,9 ± 2,6 dias, a de tempo de drenagem foi de 2,5 ± 0,7 dias, e a de volume de drenagem foi de 270,4 ± 166,7 ml. A média da perda aérea máxima foi de 92,78 ± 95,83 ml

  18. A framework to support decision making in the selection of sustainable drainage system design alternatives. (United States)

    Wang, Mingming; Sweetapple, Chris; Fu, Guangtao; Farmani, Raziyeh; Butler, David


    This paper presents a new framework for decision making in sustainable drainage system (SuDS) scheme design. It integrates resilience, hydraulic performance, pollution control, rainwater usage, energy analysis, greenhouse gas (GHG) emissions and costs, and has 12 indicators. The multi-criteria analysis methods of entropy weight and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) were selected to support SuDS scheme selection. The effectiveness of the framework is demonstrated with a SuDS case in China. Indicators used include flood volume, flood duration, a hydraulic performance indicator, cost and resilience. Resilience is an important design consideration, and it supports scheme selection in the case study. The proposed framework will help a decision maker to choose an appropriate design scheme for implementation without subjectivity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Development of Environmental Load Estimation Model for Road Drainage Systems in the Early Design Phase (United States)

    Park, Jin-Young; Lee, Dong-Eun; Kim, Byung-Soo


    Due to the increasing concern about climate change, efforts to reduce environmental load are continuously being made in construction industry, and LCA (life cycle assessment) is being presented as an effective method to assess environmental load. Since LCA requires information on construction quantity used for environmental load estimation, however, it is not being utilized in the environmental review in the early design phase where it is difficult to obtain such information. In this study, computation system for construction quantity based on standard cross section of road drainage facilities was developed to compute construction quantity required for LCA using only information available in the early design phase to develop and verify the effectiveness of a model that can perform environmental load estimation. The result showed that it is an effective model that can be used in the early design phase as it revealed a 13.39% mean absolute error rate.

  20. Sorption and distribution of aged atrazine residues in the drainage system of an outdoor lysimeter experiment (United States)

    Jablonowski, N. D.; Schäffer, A.; Burauel, P.


    Even though the environmental impact of the herbicide atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] is a matter of controversy, it is still extensively applied for agricultural purposes. Particularly in the US, atrazine has been applied to approximately 70% of all corn acreages in the last 18 years. Atrazine is banned in the EU but its use is increasing in countries like China, Brazil and India. Therefore, the worldwide soil burden of this compound must be enormous. Atrazine has been found to be highly persistent in the environment and it has been suggested that it is moderately mobile in the soil profile. As a result, it is found in most groundwater aquifers and surface waters in agricultural areas in the US. Even in Germany, where it was prohibited in 1991, it is still found in groundwater wells below agriculturally used land where it was formerly applied. For a long-term outdoor lysimeter experiment with a disturbed soil column, a drainage system of fine gravel was originally embedded at the bottom of the lysimeter. In this drainage system, atrazine and its metabolite 2-hydroxy-atrazine were extracted as long as 22 years after the last atrazine application. Due to the radiolabelling, the spatial distribution of the atrazine residues can be evaluated in fractions like fine clay particles attached to the gravel or in the gravel itself. Approximately 2% of the total gravel consisted of carbonaceous, slag-like particles which might retain most of the atrazine and its residues. The latest data will be presented at the session.

  1. Acid Mine Drainage Treatment by Perlite Nanomineral, Batch and Continuous Systems (United States)

    Shabani, Kumars Seifpanahi; Ardejani, Faramarz Doulati; Badii, Khshayar; Olya, Mohammad Ebrahim


    In this paper the adsorption activity of perlite nanoparticles for removal of Cu2+, Fe2+ and Mn2+ ions at Iran Sarcheshmeh copper acid mine drainage was discussed. Thus, raw perlite that provided from internal resource was modified and prepared via particles size reduction to nano scale and characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, transmission electron microscopy, Fourier transforms infrared and BET specific surface area analysis. The results of acid mine drainage show that pH of acid mine drainage is 5.1 and Cu2+, Fe2+ and Mn2+ ions are 10.5, 4.1 and 8.3 ppm, respectively. Firstly in the batch system the influence of adsorbent dose and temperature parameters were considered and then isothermal and kinetic models were investigated. According to the results the Langmuir isotherm and pseudo-second order kinetic model showed better correlation with the experimental data than other isotherm and kinetic models. Obtained thermodynamic parameters such as ΔG°, ΔH° and ΔS° show that the Cu2+, Fe2+ and Mn2+ ions adsorption from acid mine drainage is spontaneous and endothermic. Finally, perlite nanoparticles adsorbent was packed inside a glass column and used for the removal of heavy metals in 1, 3, 5 ml/min acid mine drainage flow rates, the breakthrough curves show that the column was saturated at 180, 240 and 315 min for different flow rates, respectively. According to the obtained results, this abundant, locally available and cheap silicate mineral showed a great efficiency for the removal of heavy metal pollutants from acid mine drainage and can be utilized for much volume of acid mine drainage or industrial scale. W pracy omówiono zdolności adsorpcyjne nano-cząsteczek perlitu wykorzystywanych o usuwania jonów Cu2+, Fe2+ i Mn2+ z kwaśnych wód kopalniach w kopalni miedzi w Sarcheshmeh w Iranie. Surowy perlit pozyskiwany ze źródeł własnych został zmodyfikowany i odpowiednio spreparowany poprzez zre-dukowanie cz

  2. Interdisciplinary semantic model for managing the design of a steam-assisted gravity drainage tooling system

    Directory of Open Access Journals (Sweden)

    Michael Leitch


    Full Text Available Complex engineering systems often require extensive coordination between different expert areas in order to avoid costly design iterations and rework. Cyber-physics system (CPS engineering methods could provide valuable insights to help model these interactions and optimize the design of such systems. In this work, steam assisted gravity drainage (SAGD, a complex oil extraction process that requires deep understanding of several physical-chemical phenomena, is examined whereby the complexities and interdependencies of the system are explored. Based on an established unified feature modeling scheme, a software modeling framework is proposed to manage the design process of the production tools used for SAGD oil extraction. Applying CPS methods to unify complex phenomenon and engineering models, the proposed CPS model combines effective simulation with embedded knowledge of completion tooling design in order to optimize reservoir performance. The system design is expressed using graphical diagrams of the unified modelling language (UML convention. To demonstrate the capability of this system, a distributed research group is described, and their activities coordinated using the described CPS model.

  3. General Technical Approvals for Decentralised Sustainable Urban Drainage Systems (SUDS—The Current Situation in Germany

    Directory of Open Access Journals (Sweden)

    Carsten Dierkes


    Full Text Available The use of decentralised, sustainable urban drainage systems (SUDS for the treatment of stormwater runoff is becoming increasingly prevalent in Germany. Decentralised SUDS can offer a viable and attractive alternative to end of pipe treatment systems for stormwater runoff from urban areas. However, there is still some uncertainty regarding the long-term performance of SUDS, and the general legislative requirements for SUDS approval and testing. Whilst the allowable pollution levels in stormwater runoff that infiltrate into ground and/or water table are regulated across Germany by the Federal Soil Protection Law, there is presently no federal law addressing the discharge requirements for surface water runoff. The lack of clear guidance can make it difficult for planners and designers to implement these innovative and sustainable stormwater treatment systems. This study clarifies the current understanding of urban stormwater treatment requirements and new technical approval guidelines for decentralised SUDS devices in Germany. The study findings should assist researchers, designers and asset managers to better anticipate and understand the performance, effective life-spans, and the planning and maintenance requirements for decentralised SUDS systems. This should help promote even greater use of these systems in the future.


    Directory of Open Access Journals (Sweden)

    V. Moca


    Full Text Available In the pedo-climatic conditions of Suceava County that extends on a total surface of 855 300 ha, the balance of agricultural land affected by humidity excess with temporar or permanent character is differenciated from south to north and from east to west, between 30 % till 40%, which means almost 100 000 ha. On these soils with underground water or pluvial excess hydro ameliorative drainage systems have been installed, associated to a complex agroameliorative works. For long effect estimation of the underground drainage asociated with the agropedoameliorative works upon the some chemical properties, there were analyzed the soil and the environment conditions from Baia field.

  5. Possible Effects on the Stability of the West Antarctic Ice Sheet (WAIS) and Associated Sea-level Rise From Active-Recent Subglacial Volcanism Interpreted from Aeromagnetic and Radar Ice-sounding Observations (United States)

    Behrendt, J. C.


    Aeromagnetic profiles (>10,000 km) acquired in the early 1960s over the West Antarctic Ice Sheet (WAIS) combined with coincident aeromagnetic and radar ice sounding in 1978-79 indicated numerous high-amplitude, shallow-source, magnetic anomalies over a very extensive area of the volcanically active West Antarctic rift system interpreted as caused by subglacial volcanic rocks. These early aerogeophysical surveys defined this area as >500,000 km2. Five-kilometer spaced coincident aeromagnetic and radar ice sounding surveys since 1990 provide three dimensional characterization of the magnetic field and bed topography beneath the ice sheet. These 5-50-km width, semicircular magnetic anomalies range from 100->1000 nT as observed ~1 km over the 2-3 km thick ice. Behrendt et al, (2005, 2008) interpreted these anomalies as indicating >1000 "volcanic centers". requiring high remanent normal (and at least 10% reversed) magnetizations in the present field direction. These data have shown that >80% of the anomaly sources at the bed of the WAIS, have been modified by the moving ice into which they were injected, requiring a younger age than the WAIS (about 25 Ma). Behrendt et al., (1994; 2007) conservatively estimated >1 x 106 km3 volume of volcanic sources to account for the area of the "volcanic center" anomalies. Although exposed volcanoes surrounding the WAIS extend in age to ~34 m.y., Mt Erebus, (Melbourne, (1000 volcanic, magnetic-anomaly sources are active today, or in the recent past, in the drainage area of the WAIS, subglacial volcanism may still have a significant effect on the dynamics of the WAIS. Interpreted active subglacial volcanism is revealed by aerogeophysical data reported by Blankenship et al., (1993, Mt. Casertz), and Corr and Vaughan, (2008, near Hudson Mts.), who raised the question of possible volcanic effects on the regime of the WAIS. Wingham et al. (2009) reported an average rate of volume loss from 2.6 to 10.1 km3/yr from 1995 to 2006 for the Pine

  6. A gain-loss framework based on ensemble flow forecasts to switch the urban drainage-wastewater system management towards energy optimization during dry periods

    DEFF Research Database (Denmark)

    Courdent, V.; Grum, M.; Munk-Nielsen, T.


    Precipitation is the cause of major perturbation to the flow in urban drainage and wastewater systems. Flow forecasts, generated by coupling rainfall predictions with a hydrologic runoff model, can potentially be used to optimize the operation of integrated urban drainage-wastewater systems (IUDWSs...

  7. Physiography and tectonic setting of the subglacial lake district between Vostok and Belgica subglacial highlands (Antarctica) (United States)

    Tabacco, I. E.; Cianfarra, P.; Forieri, A.; Salvini, F.; Zirizotti, A.


    We present the interpretation of 11 radio echo-sounding (RES) missions carried out over the Vostok-Dome Concordia region during the Italian Antarctic expeditions in the period 1995-2001. The extension and the density of the radar data in the surveyed area allowed to reconstruct a reliable subglacial morphology and to identify four relevant morphological structures namely: the Aurora trench, the Concordia trench, the Concordia ridge and the South Hills. These structures show evidence compatible with the presence of tectonic features. Morphological considerations indicate their development in Cenozoic time. Hybrid cellular automata (HCA)-based numerical modelling allowed to justify a possible role played by the tectonics of the Aurora and Concordia trench evolution. This was accomplished by matching the bed profiles along opportunely projected sections with the modelled surfaces as derived by the activity of normal faults with variable surfaces within the continental crust. The Vostok-Dome C region is characterized by a large number of subglacial lakes. From the analysis of basal reflected power echo, we identified 14 new lakes and obtained information about their physiography as well as their possible relations with tectonics. We propose a grouping of subglacial lakes on the base of their physiography and geological setting, namely relief lakes, basin lakes and trench lakes. Relief lakes located in the Belgica subglacial highlands and are characterized by sharp and steep symmetric edges, suggesting a maximum water depth of the order of 100 m. Their origin may well relate to localized, positive geothermal flux anomalies. Basin lakes located in the Vincennes subglacial basin and are characterized by wider dimension that allow the development of well-defined, flat ice surface anomalies. Trench lakes characterize the Aurora and Concordia trenches as the possible effect of normal fault activity.

  8. Fate of hydrocarbon pollutants in source and non-source control sustainable drainage systems. (United States)

    Roinas, Georgios; Mant, Cath; Williams, John B


    Sustainable drainage (SuDs) is an established method for managing runoff from developments, and source control is part of accepted design philosophy. However, there are limited studies into the contribution source control makes to pollutant removal, especially for roads. This study examines organic pollutants, total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs), in paired source and non-source control full-scale SuDs systems. Sites were selected to cover local roads, trunk roads and housing developments, with a range of SuDs, including porous asphalt, swales, detention basins and ponds. Soil and water samples were taken bi-monthly over 12 months to assess pollutant loads. Results show first flush patterns in storm events for solids, but not for TPH. The patterns of removal for specific PAHs were also different, reflecting varying physico-chemical properties. The potential of trunk roads for pollution was illustrated by peak runoff for TPH of > 17,000 μg/l. Overall there was no significant difference between pollutant loads from source and non-source control systems, but the dynamic nature of runoff means that longer-term data are required. The outcomes of this project will increase understanding of organic pollutants behaviour in SuDs. This will provide design guidance about the most appropriate systems for treating these pollutants.

  9. Recharge of a subglacial lake by surface meltwater in northeast Greenland. (United States)

    Willis, Michael J; Herried, Bradley G; Bevis, Michael G; Bell, Robin E


    In a warming climate, surface meltwater production on large ice sheets is expected to increase. If this water is delivered to the ice sheet base it may have important consequences for ice dynamics. For example, basal water distributed in a diffuse network can decrease basal friction and accelerate ice flow, whereas channelized basal water can move quickly to the ice margin, where it can alter fjord circulation and submarine melt rates. Less certain is whether surface meltwater can be trapped and stored in subglacial lakes beneath large ice sheets. Here we show that a subglacial lake in Greenland drained quickly, as seen in the collapse of the ice surface, and then refilled from surface meltwater input. We use digital elevation models from stereo satellite imagery and airborne measurements to resolve elevation changes during the evolution of the surface and basal hydrologic systems at the Flade Isblink ice cap in northeast Greenland. During the autumn of 2011, a collapse basin about 70 metres deep and about 0.4 cubic kilometres in volume formed near the southern summit of the ice cap as a subglacial lake drained into a nearby fjord. Over the next two years, rapid uplift of the floor of the basin (which is approximately 8.4 square kilometres in area) occurred as surface meltwater flowed into crevasses around the basin margin and refilled the subglacial lake. Our observations show that surface meltwater can be trapped and stored at the bed of an ice sheet. Sensible and latent heat released by this trapped meltwater could soften nearby colder basal ice and alter downstream ice dynamics. Heat transport associated with meltwater trapped in subglacial lakes should be considered when predicting how ice sheet behaviour will change in a warming climate.

  10. Impacts of climate change on rainfall extremes and urban drainage systems

    National Research Council Canada - National Science Library

    Willems, Patrick


    Impacts of Climate Change on Rainfall Extremes and Urban Drainage provides a state-of-the-art overview of existing methodologies and relevant results related to the assessment of the climate change...

  11. Corrosion control when using passively treated abandoned mine drainage as alternative makeup water for cooling systems. (United States)

    Hsieh, Ming-Kai; Chien, Shih-Hsiang; Li, Heng; Monnell, Jason D; Dzombak, David A; Vidic, Radisav D


    Passively treated abandoned mine drainage (AMD) is a promising alternative to fresh water as power plant cooling water system makeup water in mining regions where such water is abundant. Passive treatment and reuse of AMD can avoid the contamination of surface water caused by discharge of abandoned mine water, which typically is acidic and contains high concentrations of metals, especially iron. The purpose of this study was to evaluate the feasibility of reusing passively treated AMD in cooling systems with respect to corrosion control through laboratory experiments and pilot-scale field testing. The results showed that, with the addition of the inhibitor mixture orthophosphate and tolyltriazole, mild steel and copper corrosion rates were reduced to acceptable levels (< 0.127 mm/y and < 0.0076 mm/y, respectively). Aluminum had pitting corrosion problems in every condition tested, while cupronickel showed that, even in the absence of any inhibitor and in the presence of the biocide monochloramine, its corrosion rate was still very low (0.018 mm/y).

  12. Baffled duckweed pond system for treatment of agricultural drainage water containing pharmaceuticals. (United States)

    Bassuney, Doaa; Tawfik, Ahmed


    The aim of the study is to assess the efficiency of a novel bioremediation system namely baffled duckweed pond (BDWP) system for the treatment of agricultural drainage water containing pharmaceuticals at different hydraulic retention times (HRTs). The removal efficiencies of acetaminophen (ACT), amoxicillin (AMX), and ampicillin (AMP) increased from 69.3 ± 8.6 to 87.3 ± 3.5%, from 52.9 ± 9.4 to 82.9 ± 5.2%, and from 55.3 ± 7.9 to 90.6 ± 2.8% at increasing the HRT from 6 to 8 days, respectively. However, ACT, AMX, and AMP removal efficiencies were slightly improved at increasing the HRT from 8 to 12 days. Diclofenac (DFC) removal efficiencies amounted to 56.6 ± 11.6, 55.7 ± 11.9, and 28.3 ± 12.9% at an HRTs of 12, 8, and 6 days, respectively. The results showed no relationship between the uptake/absorption of pharmaceuticals fractions and BOD5/chemical oxygen demand (COD) ratio except ACT where R2 was 0.84. The effect of COD/N ratio on the removal efficiency of pharmaceuticals fractions was slight. Additional removal of pharmaceuticals fractions and nitrification occurred in carrier sponge media situated in the last compartment of the BDWP.

  13. Recovery of Rare Earth Elements and Yttrium from Passive-Remediation Systems of Acid Mine Drainage. (United States)

    Ayora, Carlos; Macías, Francisco; Torres, Ester; Lozano, Alba; Carrero, Sergio; Nieto, José-Miguel; Pérez-López, Rafael; Fernández-Martínez, Alejandro; Castillo-Michel, Hiram


    Rare earth elements and yttrium (REY) are raw materials of increasing importance for modern technologies, and finding new sources has become a pressing need. Acid mine drainage (AMD) is commonly considered an environmental pollution issue. However, REY concentrations in AMD can be several orders of magnitude higher than in naturally occurring water bodies. With respect to shale standards, the REY distribution pattern in AMD is enriched in intermediate and valuable REY, such as Tb and Dy. The objective of the present work is to study the behavior of REY in AMD passive-remediation systems. Traditional AMD passive remediation systems are based on the reaction of AMD with calcite-based permeable substrates followed by decantation ponds. Experiments with two columns simulating AMD treatment demonstrate that schwertmannite does not accumulate REY, which, instead, are retained in the basaluminite residue. The same observation is made in two field-scale treatments from the Iberian Pyrite Belt (IPB, southwest Spain). On the basis of the amplitude of this process and on the extent of the IPB, our findings suggest that the proposed AMD remediation process can represent a modest but suitable REY source. In this sense, the IPB could function as a giant heap-leaching process of regional scale in which rain and oxygen act as natural driving forces with no energy investment. In addition to having environmental benefits of its treatment, AMD is expected to last for hundreds of years, and therefore, the total reserves are practically unlimited.

  14. Acid mine drainage treatment with a combined wetland/anoxic limestone drain: Greenhouse and field systems

    Energy Technology Data Exchange (ETDEWEB)

    Skousen, J.; Sexstone, A.; Cliff, J.; Sterner, P.; Calabrese, J.; Ziemkiewicz, P.


    The most common methods for treating acid mine drainage (AMD) involve applying a strong base to neutralize the acidity and to precipitate metals. Limestone use in AMD treatment has been largely confined to anaerobic wetlands, anoxic limestone drains (ALDs) and open limestone channels. If Fe{sup 3+} and Al could be removed from AMD before introduction into limestone systems, then the use of limestone for AMD treatment could be greatly expanded. The authors developed and monitored a passive AMD system to determine if AMD containing Fe{sup 3+} as ferrous sulfides (FeS{sub x}) through sulfate reduction. Further, Fe and al may be adsorbed to organic matter in the wetland thereby eliminating the formation of metal hydroxides with subsequent plugging of limestone pores. A field scale wetland/anoxic limestone drain (WALD) system located at Douglas, WV exported net alkaline water (mean of 127 mg/L as CaCO{sub 3}) for one year. However, dissolved oxygen and Fe data suggest that poor hydraulic conductivity caused this system to act as an Fe-oxidizing system, rather than an Fe-reducing system. As such, the system's long term effectiveness for treating AMD was compromised. After five years of operation, the system still reduces the acidity of the water from about 500 mg/L as CaCO{sub 3} to about 150 mg/L. A small scale Greenhouse system performed more like an Fe-reducing system, decreasing acidity for seven months and exporting Fe{sup 2+}, although the water existing the wetland did not contain excess alkalinity. While complications arose in the authors systems due to high flows in the Douglas system and high acidity in the Greenhouse system, pre-treating AMD with organic material can improve the condition of the water for proper treatment by an ALD or underlying limestone. For low to moderate flows (<400 L/min) and low Fe concentrations (<50 mg/L), a passive system that pre-treats AMD with organic substrates and then directs the water into limestone may be effective for

  15. Geochemical processes leading to the precipitation of subglacial carbonate crusts at Bossons glacier, Mont Blanc Massif (French Alps) (United States)

    Thomazo, Christophe; Buoncristiani, Jean-Francois; Vennin, Emmanuelle; Pellenard, Pierre; Cocquerez, Theophile; Mugnier, Jean L.; Gérard, Emmanuelle


    Cold climate carbonates can be used as paleoclimatic proxies. The mineralogy and isotopic composition of subglacially precipitated carbonate crusts provide insights into the subglacial conditions and processes occurring at the meltwater-basement rock interface of glaciers. This study documents such crusts discovered on the lee side of a gneissic roche moutonnée at the terminus of the Bossons glacier in the Mont Blanc Massif area (France). The geological context and mineralogical investigations suggest that the Ca used for the precipitation of large crystals of radial fibrous sparite observed in these crusts originated from subglacial chemical weathering of Ca-bearing minerals of the local bedrock (plagioclase and amphibole). Measurements of the carbon and oxygen isotope compositions in the crusts indicate precipitation at, or near to, equilibrium with the basal meltwater under open system conditions during refreezing processes. The homogeneous and low carbonate δ13C values (ca. -11.3‰) imply a large contribution of soil organic carbon to the Bossons subglacial meltwater carbon reservoir at the time of deposition. In addition, organic remains trapped within the subglacially precipitated carbonate crusts give an age of deposition around 6500 years cal BP suggesting that the Mid-Holocene climatic and pedological optima are archived in the Bossons glacier carbonate crusts.

  16. Hydrodynamic Performances of Air-Water Flows in Gullies with and without Swirl Generation Vanes for Drainage Systems of Buildings


    Der-Chang Lo; Jin-Shuen Liou; Shyy Woei Chang


    As an attempt to improve the performances of multi-entry gullies with applications to drainage system of a building, the hydrodynamic characteristics of air-water flows through the gullies with and without swirl generation vanes (SGV) are experimentally and numerically examined. With the aid of present Charge Coupled Device (CCD) image and optical systems for experimental study, the mechanism of air entrainment by vortex, the temporal variations of airflow pressure, the trajectories of drifti...

  17. Optimization of hydrometric monitoring network in urban drainage systems using information theory. (United States)

    Yazdi, J


    Regular and continuous monitoring of urban runoff in both quality and quantity aspects is of great importance for controlling and managing surface runoff. Due to the considerable costs of establishing new gauges, optimization of the monitoring network is essential. This research proposes an approach for site selection of new discharge stations in urban areas, based on entropy theory in conjunction with multi-objective optimization tools and numerical models. The modeling framework provides an optimal trade-off between the maximum possible information content and the minimum shared information among stations. This approach was applied to the main surface-water collection system in Tehran to determine new optimal monitoring points under the cost considerations. Experimental results on this drainage network show that the obtained cost-effective designs noticeably outperform the consulting engineers' proposal in terms of both information contents and shared information. The research also determined the highly frequent sites at the Pareto front which might be important for decision makers to give a priority for gauge installation on those locations of the network.

  18. Local effects of global climate change on the urban drainage system of Hamburg. (United States)

    Krieger, Klaus; Kuchenbecker, Andreas; Hüffmeyer, Nina; Verworn, Hans-Reinhard


    The Hamburg Water Group owns and operates a sewer network with a total length of more than 5,700 km. There has been increasing attention paid to the possible impacts of predicted changes in precipitation patterns on the sewer network infrastructure. The primary objective of the work presented in this paper is an estimation of the hydraulic impacts of climate change on the Hamburg drainage system. As a first step, simulated rainfalls based on the regional climate model REMO were compared and validated with long-term precipitation measurements. In the second step, the hydraulic effects on the sewer network of Hamburg have been analyzed based on simulated long-term rainfall series for the period of 2000-2100. Simulation results show a significant increase in combined sewer overflows by 50% as well as an increase in surcharges of storm sewer manholes. However, there is still a substantial amount of uncertainty resulting from model uncertainty and unknown development of future greenhouse gas emissions. So far, there seems to be no sound basis for the implementation of an overall climate factor for sewer dimensioning for the Hamburg region. Nevertheless, possible effects of climate change should be taken into account within the planning process for major sewer extensions or modifications.

  19. SUDS (Sustainable Urban Drainage Systems: Uma Contextualização Histórica

    Directory of Open Access Journals (Sweden)

    Cristiano Poleto


    Full Text Available O fenômeno da urbanização aliado à impermeabilização do solo impede a infiltração das águas pluviais, evitando a recarga de aquíferos e gerando um aumento da variável “escoamento superficial” durante os períodos de chuva. Isso acelera a velocidade da água e, consequentemente, aumenta o volume que chega aos pontos mais baixos da bacia, provocando inundações e outros problemas recorrentes nesses períodos (erosões, assoreamentos, doenças, etc.. Esse problema provoca danos econômico-ambientais e, principalmente, expõe a vida de inúmeras pessoas em risco. Então, visando aumentar a infiltração das águas pluviais no solo e controlar o escoamento superficial, surgiu o SUDS (Sustainable Urban Drainage Systems, com sua proposta de sustentabilidade. O SUDS tem sido estudado e aplicado em vários países, especialmente em países desenvolvidos. O presente trabalho apresenta uma contextualização histórica do sistema de drenagem pluvial, desde sua origem até o SUDS, em diversos países, além de situar a realidade brasileira com relação aos aspectos de sustentabilidade em bacias hidrográficas urbanas.

  20. Probe technologies for clean sampling and measurement of subglacial lakes. (United States)

    Mowlem, Matt; Saw, Kevin; Brown, Robin; Waugh, Edward; Cardwell, Christopher L; Wyatt, James; Magiopoulos, Iordanis; Keen, Peter; Campbell, Jon; Rundle, Nicholas; Gkritzalis-Papadopoulos, Athanasios


    It is 4 years since the subglacial lake community published its plans for accessing, sampling, measuring and studying the pristine, and hitherto enigmatic and very different, Antarctic subglacial lakes, Vostok, Whillans and Ellsworth. This paper summarizes the contrasting probe technologies designed for each of these subglacial environments and briefly updates how these designs changed or were used differently when compared to previously published plans. A detailed update on the final engineering design and technical aspects of the probe for Subglacial Lake Ellsworth is presented. This probe is designed for clean access, is negatively buoyant (350 kg), 5.2 m long, 200 mm in diameter, approximately cylindrical and consists of five major units: (i) an upper power and communications unit attached to an optical and electrical conducting tether, (ii)-(iv) three water and particle samplers, and (v) a sensors, imaging and instrumentation pack tipped with a miniature sediment corer. To date, only in Subglacial Lake Whillans have instruments been successfully deployed. Probe technologies for Subglacial Lake Vostok (2014/15) and Lake Ellsworth (2012/13) were not deployed for technical reasons, in the case of Lake Ellsworth because hot-water drilling was unable to access the lake during the field season window. Lessons learned and opportunities for probe technologies in future subglacial access missions are discussed. © 2015 The Author(s).

  1. Microbial Community Structure of Subglacial Lake Whillans, West Antarctica. (United States)

    Achberger, Amanda M; Christner, Brent C; Michaud, Alexander B; Priscu, John C; Skidmore, Mark L; Vick-Majors, Trista J


    Subglacial Lake Whillans (SLW) is located beneath ∼800 m of ice on the Whillans Ice Stream in West Antarctica and was sampled in January of 2013, providing the first opportunity to directly examine water and sediments from an Antarctic subglacial lake. To minimize the introduction of surface contaminants to SLW during its exploration, an access borehole was created using a microbiologically clean hot water drill designed to reduce the number and viability of microorganisms in the drilling water. Analysis of 16S rRNA genes (rDNA) amplified from samples of the drilling and borehole water allowed an evaluation of the efficacy of this approach and enabled a confident assessment of the SLW ecosystem inhabitants. Based on an analysis of 16S rDNA and rRNA (i.e., reverse-transcribed rRNA molecules) data, the SLW community was found to be bacterially dominated and compositionally distinct from the assemblages identified in the drill system. The abundance of bacteria (e.g., Candidatus Nitrotoga, Sideroxydans, Thiobacillus, and Albidiferax) and archaea (Candidatus Nitrosoarchaeum) related to chemolithoautotrophs was consistent with the oxidation of reduced iron, sulfur, and nitrogen compounds having important roles as pathways for primary production in this permanently dark ecosystem. Further, the prevalence of Methylobacter in surficial lake sediments combined with the detection of methanogenic taxa in the deepest sediment horizons analyzed (34-36 cm) supported the hypothesis that methane cycling occurs beneath the West Antarctic Ice Sheet. Large ratios of rRNA to rDNA were observed for several operational taxonomic units abundant in the water column and sediments (e.g., Albidiferax, Methylobacter, Candidatus Nitrotoga, Sideroxydans, and Smithella), suggesting a potentially active role for these taxa in the SLW ecosystem. Our findings are consistent with chemosynthetic microorganisms serving as the ecological foundation in this dark subsurface environment, providing new

  2. Enhancing the Economic Value of Large Investments in Sustainable Drainage Systems (SuDS through Inclusion of Ecosystems Services Benefits

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    Santiago Urrestarazu Vincent


    Full Text Available Although Sustainable Drainage Systems (SuDS are used in cities across the world as effective flood adaptation responses, their economic viability has frequently been questioned. Inclusion of the monetary value of ecosystem services (ES provided by SuDS can increase the rate of return on investments made. Hence, this paper aims at reviewing the enhancement of the economic value of large-scale investments in SuDS through inclusion of ecosystem services. This study focuses on the flood reduction capacity and the ES benefits of green roofs and rain barrels in the combined sewerage network of Montevideo Municipality in Uruguay. The methodology comprises a cost–benefit analysis—with and without monetised ES provided by SuDS—of two drainage network configurations comprising: (i SuDS; and (ii SuDS and detention storage. The optimal drainage design for both these drainage configurations have been determined using SWMM-EA, a tool which uses multi-objective optimisation based evolutionary algorithm (EA and the storm water management model (SWMM. In both design configurations, total benefits comprising both flood reduction and ES benefits are always higher than their costs. The use of storage along with SuDS provides greater benefits with a larger reduction in flooding, and thus is more cost-effective than using SuDS alone. The results show that, for both of the drainage configurations, the larger investments are not beneficial unless ES benefits are taken into account. Hence, it can be concluded that the inclusion of ES benefits is necessary to justify large-scale investments in SuDS.

  3. Ion exchange system design for removal of heavy metals from acid mine drainage wastewater

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    R. S. Sapkal


    Full Text Available This paper discusses the methodology used to determine the optimal ion-exchange column size to process all separate batchesof feeds from acid mine drainage wastewater.The optimal design ensures the best utilization of resin material and therefore results in a minimum amount of spent resins.Ion exchanger materials have been studied for removing heavy metals from a metal bearing wastes. For the current treatment,a facility has been designed for the removal of heavy metals from the acid mine drainage (AMD waste by the ion-exchange technology.

  4. Uncertainty Analysis in the Evaluation of Extreme Rainfall Trends and Its Implications on Urban Drainage System Design

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    Vincenza Notaro


    Full Text Available Future projections provided by climate models suggest that the occurrence of extreme rainfall events will increase and this is evidence that the climate is changing. Because the design of urban drainage systems is based on the statistical analysis of past events, variations in the intensity and frequency of extreme rainfall represent a critical issue for the estimation of rainfall. For this reason, the design criteria of drainage systems should take into account the trends in the past and the future climate changes projections. To this end, a Bayesian procedure was proposed to update the parameters of depth–duration–frequency (DDF curves to assess the uncertainty related to the estimation of these values, once the evidence of annual maximum rainfall trends was verified. Namely, in the present study, the historical extreme rainfall series with durations of 1, 3, 6, 12 and 24 h for the period of 1950–2008, recorded by the rain gauges located near the Paceco urban area (southern Italy, were analyzed to detect statistically significant trends using the non‐parametric Mann‐Kendall test. Based on the rainfall trends, the parameters of the DDF curves for a five‐year return period were updated to define some climate scenarios. Finally, the implications of the uncertainty related to the DDF parameters estimation on the design of a real urban drainage system was assessed to provide an evaluation of its performance under the assumption of climate change. Results showed that the future increase of annual maximum precipitation in the area of study would affect the analyzed drainage system, which could face more frequent episodes of surcharge.

  5. Comparison of digital and traditional thoracic drainage systems for postoperative chest tube management after pulmonary resection: A prospective randomized trial. (United States)

    Takamochi, Kazuya; Nojiri, Shuko; Oh, Shiaki; Matsunaga, Takeshi; Imashimizu, Kota; Fukui, Mariko; Suzuki, Kenji


    The objective of this study was to evaluate whether a digital thoracic drainage system (group D) is clinically useful compared with a traditional thoracic drainage system (group T) in chest tube management following anatomic lung resection. Patients scheduled to undergo segmentectomy or lobectomy were prospectively randomized before surgery to group D or T. A stratification randomization was performed according to the following air leak risk factors: age, sex, smoking status, and presence of emphysema and/or chronic obstructive pulmonary disease. The primary end point was the duration of chest tube placement. No statistically significant differences were found between groups D (n = 135) and T (n = 164) with regard to the duration of chest tube placement (median, 2.0 vs 3.0 days; P = .149), duration of hospitalization (median, 6.0 vs 7.0 days; P = .548), or frequency of postoperative adverse events (25.1% vs 20.7%; P = .361). In subgroup analyses of the 64 patients with postoperative air leak (20 in group D and 44 in group T), the duration of chest tube placement (median, 4.5 vs 4.0 days; P = .225) and duration of postoperative air leak (median, 3.0 vs 3.0 days; P = .226) were not significantly different between subgroups. The use of a digital thoracic drainage system did not shorten the duration of chest tube placement in comparison to a traditional thoracic drainage system after anatomic lung resection. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  6. Drumlins, subglacial meltwater floods, and ocean responses (United States)

    Shaw, John


    Drumlins and erosional marks in bedrock give evidence for broad, subglacial meltwater floods that have discharge-rate estimates of about 106 m3/s. Similar discharge rates are obtained for other late glacial catastrophic floods. The total volume of meltwater that is thought to have formed the Livingstone Lake, Saskatchewan, drumlin field is estimated at 8.4 x 104 km3. This volume is equivalent to a eustatic rise of 0.23 m in global sea level. Meltwater release and roughly contemporaneous formation of drumlin fields in North America and Europe could have involved several metres of sea-level rise in a few years. The implications of such floods for the generation of myths and the interpretation of the oxygen isotopic record of the oceans are discussed. High meltwater discharges are of potential importance to the generation of a lid of cold, fresh water over the North Atlantic and its effects on late glacial climate.

  7. Strategic Framework for Sustainable Management of Drainage Systems in Semi-Arid Cities: An Iraqi Case Study

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    Mohammed Nanekely


    Full Text Available For the purpose of this paper, Erbil city, located in the northern part of Iraq, has been chosen as a representative case study for a large number of cities, particularly in semi-arid areas, lacking sustainable drainage systems (SuDS. The study assesses (a the role of SuDS as a measure in areas with a water shortage; (b water scarcity in decision-making processes; (c the lack of legislation to implement SuDS; (d the adverse effects of climate change on the urban drainage system; and (e the effects of an increased population on SuDS implementation. An integrated methodology that incorporates a self-administrated questionnaire, workshops, face-to-face communication and interviews, as well as electronic media interactions, were used to achieve the objectives. A generic platform that consists of thirteen pillars, supporting the short to long-term national policies and strategies towards a sustainable urban drainage system, has been developed. Results showed that environmental laws need to be introduced. Findings also indicate that a growing population, which is partly due to an increase of internally displaced people, is a major challenge to an early application of SuDS, due to a rise in land demand and a lack of financial resources.

  8. Decision making for urban drainage systems under uncertainty caused by weather radar rainfall measurement (United States)

    Dai, Qiang; Zhuo, Lu; Han, Dawei


    With the rapidly growth of urbanization and population, the decision making for managing urban flood risk has been a significant issue for most large cities in China. A high-quality measurement of rainfall at small temporal but large spatial scales is of great importance to urban flood risk management. Weather radar rainfall, with its advantage of short-term predictability and high spatial and temporal resolutions, has been widely applied in the urban drainage system modeling. It is recognized that weather radar is subjected to many uncertainties and many studies have been carried out to quantify these uncertainties in order to improve the quality of the rainfall and the corresponding outlet flow. However, considering the final action in urban flood risk management is the decision making such as flood warning and whether to build or how to operate a hydraulics structure, some uncertainties of weather radar may have little or significant influence to the final results. For this reason, in this study, we aim to investigate which characteristics of the radar rainfall are the significant ones for decision making in urban flood risk management. A radar probabilistic quantitative rainfall estimated scheme is integrated with an urban flood model (Storm Water Management Model, SWMM) to make a decision on whether to warn or not according to the decision criterions. A number of scenarios with different storm types, synoptic regime and spatial and temporal correlation are designed to analyze the relationship between these affected factors and the final decision. Based on this, parameterized radar probabilistic rainfall estimation model is established which reflects the most important elements in the decision making for urban flood risk management.

  9. Removal of sulphates acidity and iron from acid mine drainage in a bench scale biochemical treatment system. (United States)

    Prasad, D; Henry, J G


    The focus of this study was to develop a simple biochemical system to treat acid mine drainage for its safe disposal. Recovery and reuse of the metals removed were not considered. A three-step process for the treatment of acid mine drainage (AMD), proposed earlier, separates sulphate reducing activity from metal precipitation units and from a pH control system. Following our earlier work on the first step (biological reactor), this paper examines the second step (i.e. chemical reactor). The objectives of this study were: (1) to determine the increase in pH and the reduction of iron in the chemical reactor for different proportions of simulated AMD, and (2) to assess the capability of the chemical reactor. A series of experiments was conducted to study the effects of addition of alkaline sulphidogenic liquor (ASL) derived from a batch sulphidogenic biological reactor (operating with activated sludge and a COD/SO4 ratio of 1.6) on the simulated AMD characteristics. At 60-minute contact time, addition of 30% ASL (pH of 7.60-7.76) to the chemical reactor with 70% AMD (pH of 1.65-2.02), increased the pH of the AMD to 6.57 and alkalinity from 0 to 485 mg l(-1) as CaCO3, respectively and precipitated about 97% of the iron present in the simulated AMD. Others have demonstrated that metals in mine drainage can be precipitated by bacterial sulphate reduction. In this study, iron, a common and major component of mine drainage was used as a surrogate for metals in general. The results indicate the feasibility of treating AMD by an engineered sulphidogenic anaerobic reactor followed by a chemical reactor and that our three-step biochemical process has important advantages over other conventional AMD treatment systems.

  10. Antarctic Active Subglacial Lake Inventory from ICESat Altimetry, Version 1 (United States)

    National Aeronautics and Space Administration — This data set contains lake boundaries, volume changes, and gridded elevations for 124 active subglacial lakes beneath the Antarctic ice sheet. Lakes were identified...

  11. Does the usage of digital chest drainage systems reduce pleural inflammation and volume of pleural effusion following oncologic pulmonary resection?-A prospective randomized trial. (United States)

    De Waele, Michèle; Agzarian, John; Hanna, Waël C; Schieman, Colin; Finley, Christian J; Macri, Joseph; Schneider, Laura; Schnurr, Terri; Farrokhyar, Forough; Radford, Katherine; Nair, Parameswaran; Shargall, Yaron


    Prolonged air leak and high-volume pleural drainage are the most common causes for delays in chest tube removal following lung resection. While digital pleural drainage systems have been successfully used in the management of post-operative air leak, their effect on pleural drainage and inflammation has not been studied before. We hypothesized that digital drainage systems (as compared to traditional analog continuous suction), using intermittent balanced suction, are associated with decreased pleural inflammation and postoperative drainage volumes, thus leading to earlier chest tube removal. One hundred and three [103] patients were enrolled and randomized to either analog (n=50) or digital (n=53) drainage systems following oncologic lung resection. Chest tubes were removed according to standardized, pre-defined protocol. Inflammatory mediators [interleukin-1B (IL-1B), 6, 8, tumour necrosis factor-alpha (TNF-α)] in pleural fluid and serum were measured and analysed. The primary outcome of interest was the difference in total volume of postoperative fluid drainage. Secondary outcome measures included duration of chest tube in-situ, prolonged air-leak incidence, length of hospital stay and the correlation between pleural effusion formation, degree of inflammation and type of drainage system used. There was no significant difference in total amount of fluid drained or length of hospital stay between the two groups. A trend for shorter chest tube duration was found with the digital system when compared to the analog (P=0.055). Comparison of inflammatory mediator levels revealed no significant differences between digital and analog drainage systems. The incidence of prolonged post-operative air leak was significantly higher when using the analog system (9 versus 2 patients; P=0.025). Lobectomy was associated with longer chest tube duration (P=0.001) and increased fluid drainage when compared to sub-lobar resection (Pdigital drainage does not appear to decrease pleural

  12. Forest drainage (United States)

    R.W. Skaggs; S. Tian; G.M. Chescheir; Devendra Amatya; M.A. Youssef


    Most of the world's 4030 million ha of forested lands are situated on hilly, mountainous or well-drained upland landscapes where improved drainage is not needed. However, there are millions of hectares of poorly drained forested lands where excessively wet soil conditions limit tree growth and access for harvesting and other management activities. Improved or...

  13. Use of Natural and Applied Tracers to Guide Targeted Remediation Efforts in an Acid Mine Drainage System, Colorado Rockies, USA

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    Rory Cowie


    Full Text Available Stream water quality in areas of the western United States continues to be degraded by acid mine drainage (AMD, a legacy of hard-rock mining. The Rico-Argentine Mine in southwestern Colorado consists of complex multiple-level mine workings connected to a drainage tunnel discharging AMD to passive treatment ponds that discharge to the Dolores River. The mine workings are excavated into the hillslope on either side of a tributary stream with workings passing directly under the stream channel. There is a need to define hydrologic connections between surface water, groundwater, and mine workings to understand the source of both water and contaminants in the drainage tunnel discharge. Source identification will allow targeted remediation strategies to be developed. To identify hydrologic connections we employed a combination of natural and applied tracers including isotopes, ionic tracers, and fluorescent dyes. Stable water isotopes (δ18O/δD show a well-mixed hydrological system, while tritium levels in mine waters indicate a fast flow-through system with mean residence times of years not decades or longer. Addition of multiple independent tracers indicated that water is traveling through mine workings with minimal obstructions. The results from a simultaneous salt and dye tracer application demonstrated that both tracer types can be successfully used in acidic mine water conditions.

  14. Prospects of obtaining samples of bottom sediments from subglacial lake Vostok

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    Н. И. Васильев


    Full Text Available The paper proves the timeliness of obtaining and examining bottom sediments from subglacial Lake Vostok. Predictive geological section of Lake Vostok and information value of bottom sediments have been examined. Severe requirements towards environmental security of lake examinations and sampling of bottom sediments rule out the use of conventional drilling technologies, as they would pollute the lake with injection liquid from the borehole. In order to carry out sampling of bottom sediments from the subglacial lake, it is proposed to use a dynamically balanced tool string, which enables rotary drilling without any external support on borehole walls to transmit counter torque.     A theoretical analysis has been carried out to assess the operation of the tool string, which is a two-mass oscillatory electromechanical system of reciprocating and rotating motion (RRM with two degrees of freedom.

  15. Rock comminution as a source of hydrogen for subglacial ecosystems (United States)

    Telling, J.; Boyd, E. S.; Bone, N.; Jones, E. L.; Tranter, M.; Macfarlane, J. W.; Martin, P. G.; Wadham, J. L.; Lamarche-Gagnon, G.; Skidmore, M. L.; Hamilton, T. L.; Hill, E.; Jackson, M.; Hodgson, D. A.


    Substantial parts of the beds of glaciers, ice sheets and ice caps are at the pressure melting point. The resulting water harbours diverse subglacial microbial ecosystems capable of affecting global biogeochemical cycles. Such subglacial habitats may have acted as refugia during Neoproterozoic glaciations. However, it is unclear how life in subglacial environments could be supported during glaciations lasting millions of years because energy from overridden organic carbon would become increasingly depleted. Here we investigate the potential for abiogenic H2 produced during rock comminution to provide a continual source of energy to support subglacial life. We collected a range of silicate rocks representative of subglacial environments in Greenland, Canada, Norway and Antarctica and crushed them with a sledgehammer and ball mill to varying surface areas. Under an inert atmosphere in the laboratory, we added water, and measured H2 production with time. H2 was produced at 0 °C in all silicate-water experiments, probably through the reaction of water with mineral surface silica radicals formed during rock comminution. H2 production increased with increasing temperature or decreasing silicate rock grain size. Sufficient H2 was produced to support previously measured rates of methanogenesis under a Greenland glacier. We conclude that abiogenic H2 generation from glacial bedrock comminution could have supported life and biodiversity in subglacial refugia during past extended global glaciations.

  16. An Active Englacial Hydrological System in a Cold Glacier: Blood Falls, Taylor Glacier, Antarctica (United States)

    Carr, C. G.; Pettit, E. C.; Carmichael, J.; Badgeley, J.; Tulaczyk, S. M.; Lyons, W. B.; Mikucki, J.


    Blood Falls is a supraglacial hydrological feature formed by episodic release of iron-rich subglacial brine derived from an extensive aquifer beneath the cold, polar, Taylor Glacier. While fluid transport in non-temperate ice typically occurs through meltwater delivery from the glacier surface to the bed (hydrofracturing, supraglacial lake drainage), Blood Falls represents the opposite situation: brine moves from a subglacial source to the glacier surface. Here, we present the first complete conceptual model for brine transport and release, as well as the first direct evidence of a wintertime brine release at Blood Falls obtained through year-round time-lapse photography. Related analyses show that brine pools subglacially underneath the northern terminus of Taylor Glacier, rather than flowing directly into proglacial Lake Bonney because ice-cored moraines and channelized surface topography provide hydraulic barriers. This pooled brine is pressurized by hydraulic head from the upglacier brine source region. Based on seismic data, we propose that episodic supraglacial release is initiated by high strain rates coupled with pressurized subglacial brine that drive intermittent subglacial and englacial fracturing. Ultimately, brine-filled basal crevasses propagate upward to link with surface crevasses, allowing brine to flow from the bed to the surface. The observation of wintertime brine release indicates that surface-generated meltwater is not necessary to trigger crack propagation or to maintain the conduit as previously suggested. The liquid brine persists beneath and within the cold ice (-17°C) despite ambient ice/brine temperature differences of as high as 10°C through both locally depressed brine freezing temperatures through cryoconcentration of salts and increased ice temperatures through release of latent heat during partial freezing of brine. The existence of an englacial hydrological system initiated by basal crevassing extends to polar glaciers a process

  17. Biogeochemistry of the compost bioreactor components of a composite acid mine drainage passive remediation system

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    Johnson, D. Barrie [School of Biological Sciences Memorial Building, Deiniol Road Bangor, LL57 2UW (United Kingdom)]. E-mail:; Hallberg, Kevin B. [School of Biological Sciences Memorial Building, Deiniol Road Bangor, LL57 2UW (United Kingdom)


    The compost bioreactor ('anaerobic cell') components of three composite passive remediation systems constructed to treat acid mine drainage (AMD) at the former Wheal Jane tin mine, Cornwall, UK were studied over a period of 16 months. While there was some amelioration of the preprocessed AMD in each of the three compost bioreactors, as evidenced by pH increase and decrease in metal concentrations, only one of the cells showed effective removal of the two dominant heavy metals (iron and zinc) present. With two of the compost bioreactors, concentrations of soluble (ferrous) iron draining the cells were significantly greater than those entering the reactors, indicating that there was net mobilisation (by reductive dissolution) of colloidal and/or solid-phase ferric iron compounds within the cells. Soluble sulfide was also detected in waters draining all three compost bioreactors which was rapidly oxidised, in contrast to ferrous iron. Oxidation and hydrolysis of iron, together with sulfide oxidation, resulted in reacidification of processed AMD downstream of the compost bioreactors in two of the passive treatment systems. The dominant cultivatable microorganism in waters draining the compost bioreactors was identified, via analysis of its 16S rRNA gene, as a Thiomonas sp. and was capable of accelerating the dissimilatory oxidation of both ferrous iron and reduced sulfur compounds. Sulfate-reducing bacteria (SRB) were also detected, although only in the bioreactor that was performing well were these present in significant numbers. This particular compost bioreactor had been shut down for 10 months prior to the monitoring period due to operational problems. This unforeseen event appears to have allowed more successful development of AMD-tolerant and other microbial populations with critical roles in AMD bioremediation, including neutrophilic SRB (nSRB), in this compost bioreactor than in the other two, where the throughput of AMD was not interrupted. This

  18. Alternative study of type and location of flood control infrastructure in the drainage system, Avfour Kelor channel, Tuban regency (United States)

    Sabrang, Rangga Adi; Wardoyo, Wasis


    The topography of Tuban Regency which is close to the sea has both advantage and disadvantage. The advantage is the main channels of drainage can be directly discharged into the sea, while the disadvantage is the flow of the channels will be influenced by the sea tide. However, the absence of the channel capacity of drainage to load the runoff from the catchment area of Afvour Kelor channel led to inundations in the downstream and upstream. In addition, in the middle of the downstream and the upstream of Afvour Kelor channel, precisely in the Perbon Village, inundation frequently takes place particularly in the rainy season. It is allegedly caused by, the extreme runoff from the catchment area of Afvour Kelor channel, in addition to the influence of the sea tide. Due to the prevailing problem and the absence of the solution from the related institutions, the effort to manage drainage system in the area through the debit arrangement of runoff of Afvour Kelor cannel is urgently required. There were 3 (three) flood control scenarios that were simulated in this research. The scenarios in this research consisted of: to join the plan from the location of 7 (seven) ponds, 1 (one) pond at a predetermined location, and normalization of the channel. Subsequently, the most optimal scenario would be selected and reviewed based on the water surface profile in the cross section of the lowest Avfour Kelor channel.

  19. The use of magmatic water to reconstruct palaeo-ice thicknesses during subglacial rhyolitic eruptions (United States)

    Owen, Jacqueline; Tuffen, Hugh; McGarvie, Dave; Pinkerton, Harry; Wilson, Lionel


    Magma degassing patterns can potentially be used to reconstruct ice thicknesses during subglacial eruptions, as the pressure dependence of water solubility in silicate melts is reasonably well constrained. The amount of water remaining in the quenched bulk glasses should record the quenching pressure, which, in a subglacial setting, will be dependent on the pressure of overlying ice and/or meltwater that was present. This reconstruction technique has been applied to several basaltic volcanoes[1]. In one study the dissolved water contents was seen to vary as a function of altitude, consistent with the presence of an ice sheet[2]. Similar techniques have been applied to a rhyolitic volcano, as described below. Bláhnúkur is a small-volume rhyolitic, subglacial volcano at Torfajökull volcano, southern Iceland[3] that erupted at ~95 ka[4]. 45 glassy lava samples were collected from a variety of elevations and lithofacies types. These samples were analysed for water content using infra-red spectroscopy (FTIR), and pressure-solubility relationships were calculated using VolatileCalc[5]. The results reveal a general decrease in water concentration with elevation, consistent with the presence of an ice sheet with a surface elevation of ~1,050 m a.s.l.. This corresponds with an ice thickness of ~450 m, consistent with the field evidence from tuyas of a similar age within the same region[6]. Furthermore, the results suggest an eruptive temperature of 850°C and 0 ppm CO2. However, not all samples agree with this overall trend. We suggest that samples with anomalously low water contents could have formed in regions where there was meltwater drainage which lowered the quenching pressure[7]. By contrast, water-rich samples could reflect intrusive formation resulting in loading by rock as well as ice[8]. Crucially though, the anomalous values are all from the same locations, suggesting that there are processes that are specifically affecting certain localities. In order to use

  20. Seasonal speed-up of large Greenland marine-terminating outlet glacier related to surface melt-induced changes in subglacial hydrology (United States)

    Mair, D.; Sole, A.; Nienow, P. W.; Bartholomew, I. D.


    The Greenland Ice Sheet (GrIS) has experienced increased rates of mass loss over the last decade due to increased surface melt and runoff and accelerated ice discharge. Two principal links between climate and ice discharge have been proposed. The first suggests that changes at the calving front of marine-terminating glaciers reduce resistive forces resulting in glacier acceleration and thinning or ‘draw-down’, while the second postulates that increased surface melt reaches the ice sheet bed locally and causes enhanced basal sliding, again leading to draw-down. Marine-terminating GrIS outlet glaciers generally display less sensitivity to variations in surface meltwater availability. Seasonal velocity variations have previously been explained by variations in calving rates due to the break up of the seasonal ice mélange or the ungrounding of ice near the terminus. Here we present sub-daily GPS ice velocity, surface lowering and air temperature measurements spanning the 2009 melt season along a flow line of Kangiata Nunata Sermia (KNS), the largest marine-terminating outlet glacier in South West Greenland. Surface velocity was measured at four GPS sites located 32-76 km from the calving front. A timelapse camera was installed with a field of view encompassing the calving terminus of KNS. The seasonal growth and drainage of supra-glacial lakes within the catchment was identified from MODIS imagery. The GPS data show multiple 2- to 12- day speed up events, often coincident with surface uplift, superimposed on a period of generally elevated velocity lasting 2 to 3 months. Reductions in lake volume were coincident with speed-up events at the nearby GPS sites providing strong evidence that these lakes drained to the glacier bed. These large volumes of meltwater were interpreted to be input to an inefficient, distributed drainage system creating episodes of high subglacial water pressure, hydraulic jacking and enhanced basal sliding. We conclude that between 36 km and

  1. Determination of bleb capsule porosity with an experimental glaucoma drainage device and measurement system. (United States)

    Ross, Craig; Pandav, Surinder Singh; Li, Yu Qin; Nguyen, Dan Q; Beirne, Stephen; Wallace, Gordon G; Shaarawy, Tarek; Crowston, Jonathan G; Coote, Michael


    Control of intraocular pressure after implantation of a glaucoma drainage device (GDD) depends on the porosity of the capsule that forms around the plate of the GDD. To compare capsular porosity after insertion of 2 different GDDs using a novel implant and measurement system. We performed an experimental interventional study at an eye research facility in a tertiary eye care center. Testing was performed on 22 adult New Zealand white rabbits that received the experimental GDD or an existing GDD. A new experimental GDD, the Center for Eye Research Australia (CERA) implant, was created using computer-aided design and a 3-dimensional printer. The CERA GDDs were implanted in the eyes of rabbits randomized into 1 of the following 3 groups: with no connection to the anterior chamber (n = 7), with connection to the anterior chamber for 1 week (n = 5), and with connection to the anterior chamber for 4 weeks (n = 5). In a control group (n = 5), a pediatric GDD was implanted without connection to the anterior chamber. We measured the capsular porosity using a pressure-gated picoliter pump at a driving pressure of 12 mm Hg. The animals were killed humanely for histologic study. Porosity of the fibrous capsule around the implant. We found no difference in mean (SEM) capsular porosity between the CERA (3.39 [0.76; 95% CI, 1.43-5.48] µL/min) and pediatric (4.52 [0.52; 95% CI, 3.19-5.95] µL/min) GDDs (P = .28, unpaired t test) at 4 weeks without aqueous exposure. Mean (SEM) capsular porosity of CERA GDDs connected to the anterior chamber at 1 week was 2.46 (0.36; 95% CI, 1.55-3.44) µL/min but decreased to 0.67 (0.07; 95% CI, 0.49-0.86) µL/min at 4 weeks (P = .001, unpaired t test). Our experimental method permits direct measurement of capsular porosity of an in situ GDD. In a comparison between an experimental (CERA) and an existing GDD, no differences were identified in capsular porosity or histologic reaction between the implants. These results suggest that the CERA GDD

  2. MatSWMM - An open-source toolbox for designing real-time control of urban drainage systems


    Riaño-Briceño, G.; Barreiro-Gómez, Julian; Ramirez-Jaime, A.; Quijano, Nicanor; Ocampo-Martinez, Carlos


    This manuscript describes the MatSWMM toolbox, an open-source Matlab, Python, and LabVIEW-based software package for the analysis and design of real-time control (RTC) strategies in urban drainage systems (UDS). MatSWMM includes control-oriented models of UDS, and the storm water management model (SWMM) of the US Environmental Protection Agency (EPA), as well as systematic-system edition functionalities. Furthermore, MatSWMM is also provided with a population-dynamics-based controller for UDS...

  3. Rapid Submarine Melting Driven by Subglacial Discharge, LeConte Glacier, Alaska (United States)

    Motyka, R. J.; Dryer, W. P.; Amundson, J. M.; Truffer, M.; Fahnestock, M. A.


    pattern. Although this circulation pattern is generally supported by our results, we also see evidence of eddying both at the terminus and down fjord, which adds complexity to the simple two layer model. Our results demonstrate that turbulent subglacial discharge is a key driver of ice-proximal fjord circulation that entrains warm seawater and melts submarine glacial ice. With projected continued global warming and increased glacial runoff, our results highlight the direct impact that increases in subglacial discharge will have on the stability of polar and subpolar tidewater outlet systems. These effects and feedbacks must be considered when modeling glacier response to future warming and increased runoff. Our results have direct implications for predicting future behavior at the ice sheet ocean interface, which constitutes the major uncertainty for future predictions of ice loss and sea-level rise.

  4. The Subglacial Access and Fast Ice Research Experiment - SAFIRE - on Store Glacier, West Greenland (United States)

    Christoffersen, P.; Hubbard, B. P.; Doyle, S. H.; Young, T. J.; Hofstede, C. M.; Bougamont, M. H.; Todd, J.; Toberg, N.; Nicholls, K. W.; Box, J.; Walter, J. I.; Hubbard, A.


    Marine-terminating outlet glaciers drain 90 percent of the Greenland Ice Sheet and are responsible for about half of the ice sheet's net annual mass loss, which currently raises global sea level by 1 mm per year. The basal controls on these fast-flowing glaciers are, however, poorly understood, with the implication that numerical ice sheet models needed to predict future dynamic ice loss from Greenland relies on uncertain and often untested basal parameterizations. The Subglacial Access and Fast Ice Research Experiment - SAFIRE - is addressing this paucity of observational constraints by drilling to the bed of Store Glacier, a fast-flowing outlet glacier terminating in Uummannaq Fjord, West Greenland. In 2014, we gained access to the bed in four boreholes drilled to depths of 603-616 m near the center of the glacier, 30 km inland from the calving terminus where ice flows at a rate of 700 m/year. A seismic survey showed the glacier bed to consist of water-saturated, soft sediment. The water level in all four boreholes nevertheless dropped rapidly to 80 m below the ice surface when the drill connected with a basal water system, indicating effective drainage over a sedimentary bed. We were able to install wired sensor strings at the bed (water pressure, temperature, electrical conductivity and turbidity) and within the glacier (temperature and tilt) in three boreholes. The sensors operated for up to 80+ days before cables stretched and ultimately snapped due to high internal strain. The data collected during this sensor deployment show ice as cold as -21 degrees Celcius; yet, temperature of water in the basal water system was persistently above the local freezing point. With diurnal variations detected in several sensor records, we hypothesise that surface water lubricates the ice flow while also warming basal ice. The fast basal motion of Store Glacier not only occurs by basal sliding, but from high rates of concentrated strain in the bottom third of the glacier

  5. A geographic information system screening tool to tackle diffuse pollution through the use of sustainable drainage systems. (United States)

    Todorovic, Zorica; Breton, Neil P


    Sustainable drainage systems (SUDS) offer many benefits that traditional solutions do not. Traditional approaches are unable to offer a solution to problems of flood management and water quality. Holistic consideration of the wide range of benefits from SUDS can result in advantages such as improved flood resilience and water quality enhancement through consideration of diffuse pollution sources. Using a geographical information system (GIS) approach, diffuse pollutant sources and opportunities for SUDS are easily identified. Consideration of potential SUDS locations results in source, site and regional controls, leading to improved water quality (to meet Water Framework Directive targets). The paper will discuss two different applications of the tool, the first of which is where the pollutant of interest is known. In this case the outputs of the tool highlight and isolate the areas contributing the pollutants and suggest the adequate SUDS measures to meet the required criteria. The second application is where the tool identifies likely pollutants at a receiving location, and SUDS measures are proposed to reduce pollution with assessed efficiencies.

  6. Impact of tile drainage on evapotranspiration in South Dakota, USA, based on high spatiotemporal resolution evapotranspiration time series from a multi-satellite data fusion system (United States)

    Yang, Yun; Anderson, Martha C.; Gao, Feng; Hain, Christopher; Kustas, William P.; Meyers, Tilden P.; Crow, Wade; Finocchiaro, Raymond G.; Otkin, Jason; Sun, Liang; Yang, Yang


    Soil drainage is a widely used agricultural practice in the midwest USA to remove excess soil water to potentially improve the crop yield. Research shows an increasing trend in baseflow and streamflow in the midwest over the last 60 years, which may be related to artificial drainage. Subsurface drainage (i.e., tile) in particular may have strongly contributed to the increase in these flows, because of its extensive use and recent gain in the popularity as a yield-enhancement practice. However, how evapotranspiration (ET) is impacted by tile drainage on a regional level is not well-documented. To explore spatial and temporal ET patterns and their relationship to tile drainage, we applied an energy balance-based multisensor data fusion method to estimate daily 30-m ET over an intensively tile-drained area in South Dakota, USA, from 2005 to 2013. Results suggest that tile drainage slightly decreases the annual cumulative ET, particularly during the early growing season. However, higher mid-season crop water use suppresses the extent of the decrease of the annual cumulative ET that might be anticipated from widespread drainage. The regional water balance analysis during the growing season demonstrates good closure, with the average residual from 2005 to 2012 as low as -3 mm. As an independent check of the simulated ET at the regional scale, the water balance analysis lends additional confidence to the study. The results of this study improve our understanding of the influence of agricultural drainage practices on regional ET, and can affect future decision making regarding tile drainage systems.

  7. Forecast generation for real-time control of urban drainage systems using greybox modelling and radar rainfall

    DEFF Research Database (Denmark)

    Löwe, Roland; Mikkelsen, Peter Steen; Madsen, Henrik


    We present stochastic flow forecasts to be used in a real-time control setup for urban drainage systems. The forecasts are generated using greybox models with rain gauge and radar rainfall observations as input. Predictions are evaluated as intervals rather than just mean values. We obtain...... satisfactory predictions for the smaller catchment but rather large uncertainties for the bigger catchment where the applied storage cascade seems too simple. Radar rainfall introduces more uncertainty into the flow forecast model estimation. However, the radar rainfall forecasts also result in a slightly...

  8. Height changes over subglacial Lake Vostok, East Antarctica: Insights from GNSS observations

    National Research Council Canada - National Science Library

    Richter, Andreas; Popov, Sergey V; Fritsche, Mathias; Lukin, Valery V; Matveev, Alexey Yu; Ekaykin, Alexey A; Lipenkov, Vladimir Ya; Fedorov, Denis V; Eberlein, Lutz; Schröder, Ludwig; Ewert, Heiko; Horwath, Martin; Dietrich, Reinhard


    Height changes of the ice surface above subglacial Lake Vostok, East Antarctica, reflect the integral effect of different processes within the subglacial environment and the ice sheet. Repeated GNSS...

  9. Investigating the hydrological origins of Blood Falls - geomicrobiological insights into a briny subglacial Antarctic aquifer (United States)

    Mikucki, J.; Tulaczyk, S. M.; Purcell, A. M.; Dachwald, B.; Lyons, W. B.; Welch, K. A.; Auken, E.; Dugan, H. A.; Walter, J. I.; Pettit, E. C.; Doran, P. T.; Virginia, R. A.; Schamper, C.; Foley, N.; Feldmann, M.; Espe, C.; Ghosh, D.; Francke, G.


    Subglacial waters tend to accumulate solutes from extensive rock-water interactions, which, when released to the surface, can provide nutrients to surface ecosystems providing a 'hot spot' for microbial communities. Blood Falls, an iron-rich, saline feature at the terminus of Taylor Glacier in the McMurdo Dry Valleys, Antarctica is a well-studied subglacial discharge. Here we present an overview of geophysical surveys, thermomechanical drilling exploration and geomicrobiological analyses of the Blood Falls system. A helicopter-borne transient electromagnetic system (SkyTEM) flown over the Taylor Glacier revealed a surprisingly extensive subglacial aquifer and indicates that Blood Falls may be the only surface manifestation of this extensive briny groundwater. Ground-based temperature sensing and GPR data combined with the helicopter-borne TEM data enabled targeted drilling into the englacial conduit that delivers brine to the surface. During the 2014-15 austral summer field season, we used a novel ice-melting drill (the IceMole) to collect englacial brine for geomicrobiological analyses. Results from previously collected outflow and more recent samples indicate that the brine harbors a metabolically active microbial community that persists, despite cold, dark isolation. Isotope geochemistry and molecular analysis of functional genes from BF suggested that a catalytic or 'cryptic' sulfur cycle was linked to iron reduction. Recent metagenomic analysis confirms the presence of numerous genes involved in oxidative and reductive sulfur transformations. Metagenomic and metabolic activity data also indicate that subglacial dark CO2 fixation occurs via various pathways. Genes encoding key steps in CO2 fixation pathways including the Calvin Benson Basham and Wood Ljungdahl pathway were present and brine samples showed measureable uptake of 14C-labeled bicarbonate. These results support the notion that, like the deep subsurface, subglacial environments are chemosynthetic

  10. Geochemical Processes Leading to the Precipitation of Subglacial Carbonate Crusts at Bossons Glacier, Mont Blanc Massif (French Alps

    Directory of Open Access Journals (Sweden)

    Christophe Thomazo


    Full Text Available Cold climate carbonates can be used as paleoclimatic proxies. The mineralogy and isotopic composition of subglacially precipitated carbonate crusts (SPCCs provide insights into the subglacial conditions and processes occurring at the meltwater-basement rock interface of glaciers. This study documents such crusts discovered on the lee side of a gneissic roche moutonnée at the terminus of the Bossons glacier in the Mont Blanc Massif area (France. The geological context and mineralogical investigations suggest that the Ca used for the precipitation of large crystals of radial fibrous sparite observed in these crusts originated from subglacial chemical weathering of Ca-bearing minerals of the local bedrock (plagioclase and amphibole. Measurements of the carbon and oxygen isotope compositions in the crusts indicate precipitation at, or near to, equilibrium with the basal meltwater under open system conditions during refreezing processes. The homogeneous and low carbonate δ13C values (ca. −11.3‰ imply a large contribution of soil organic carbon to the Bossons subglacial meltwater carbon reservoir at the time of deposition. In addition, organic remains trapped within the SPCCs give an age of deposition around 6,500 years cal BP suggesting that the Mid-Holocene climatic and pedological optima are archived in the Bossons glacier carbonate crusts.

  11. Hydrodynamic Performances of Air-Water Flows in Gullies with and without Swirl Generation Vanes for Drainage Systems of Buildings

    Directory of Open Access Journals (Sweden)

    Der-Chang Lo


    Full Text Available As an attempt to improve the performances of multi-entry gullies with applications to drainage system of a building, the hydrodynamic characteristics of air-water flows through the gullies with and without swirl generation vanes (SGV are experimentally and numerically examined. With the aid of present Charge Coupled Device (CCD image and optical systems for experimental study, the mechanism of air entrainment by vortex, the temporal variations of airflow pressure, the trajectories of drifting air bubbles and the self-depuration process for the gullies with and without SGV are disclosed. The numerical simulations adopt Flow-3D commercial code to attack the unsteady two-phase bubbly flows for resolving the transient fields of fluid velocity, vorticity and pressure in the gullies with and without SGV. In the twin-entry gully without SGV, air bubbles entrained by the entry vortex interact chaotically in the agitating bubbly flow region. With SGV to trip near-wall flows that stratify the drifting trajectories of the air bubbles, the air-bubble interactions are stabilized with the discharge rate increasing more than 7%. The reduction of the self-depuration period by increasing discharge rate is observed for the test gullies without and with SGV. Based on the experimental and numerical results, the characteristic hydrodynamic properties of the air-water flows through the test gullies with and without SGV are disclosed to assist the design applications of a modern drainage system in a building.

  12. Monitoring the future behaviour of urban drainage system under climate change: a case study from north-western England (United States)

    Osman, Yassin Z.


    Catchments hydrological conditions and responses are anticipated to be affected by the changes in weather patterns, increasing in climate variability and extreme rainfall. Thus, engineers have no choice but to consider climate change in their practices in order to adapt and serve the public interests. This paper is an exploration of the impacts of climate change on the hydrology that underlies the hydraulic design of urban drainage system. Future rainfall has been downscaled from the Global Climate Model (GCM) employing a hybrid Generalised Linear Model (GLM) and Artificial Neural Network (ANN) downscaling techniques under different greenhouse emission scenarios. The output from this model is applied to a combined sewer system of an urban drainage catchment in the Northwest of England during the 21st Century to monitor its future behaviour in winter and summer seasons. Potential future changes in rainfall intensity are expected to alter the level of service of the system, causing more challenges in terms of surface flooding and increase in surcharge level in sewers. The results obtained demonstrate that there is a real chance for these effects to take place and therefore would require more attention from designers and catchment managers.

  13. Numerical modelling of esker formation in semi-circular subglacial channels (United States)

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


    Eskers hold valuable information about past subglacial hydraulic conditions in their spatial organization, geometry, and sedimentary structures. The relations between hydraulic conditions and esker properties are nevertheless intricate as the formation of eskers has been mainly inferred from descriptive theories, about which a consensus has yet to be reached. Eskers are prevalent in areas of rigid bed and thin till cover and their formation is thought to be predominantly controlled by either water or sediment availability. In this study, we develop a 1-D numerical model of sediment transport in semi-circular bedrock-floored channels to explore the physical processes leading to esker formation. The model encompasses channel evolution by melt-opening created by the viscous heat dissipated as water flows, the creep closure of the ice walls, and changes in cross-sectional area due to sediment accumulation and removal. We find that a bottleneck in sediment transport close to the terminus is an inherent characteristic of subglacial channels. Creep closure is reduced as the ice thins towards the terminus and hydraulic potential gradients decline, thus reducing shear stresses. This bottleneck is accentuated when water discharge drops in a well established channel. We find the conditions most conducive to sediment deposition are low ice-surface slopes within several kilometres of the terminus and water discharge fluctuations over a few to several weeks. The model also produces shear stresses large enough to transport boulders under typical melt-season conditions. Our results thus suggest that incipient eskers form toward the end of the melt season, provided water input and sediment supply are sufficient. Overall these findings corroborate the theory that eskers are formed progressively during the waning stage of an ice sheet, although we suggest that eskers are a natural manifestation of the subglacial hydraulic system in the presence of an adequate trade-off between

  14. Geophysical investigations of subglacial Antarctic lakes: identifying drill sites for lake access (United States)

    Woodward, J.; Tulaczyk, S. M.; Smith, A.; Walter, J.; Ross, N.; Fricker, H. A.; Siegert, M. J.; Pettersson, R.; Thoma, M.; Corr, H.; King, E. C.; Vaughan, D.


    Subglacial lakes are regarded as viable habitats for novel microbial life forms and may contain sedimentary palaeo-environmental records which would provide critical insights into the glacial history of Antarctica. In-situ sampling and analysis is the only way to explore these lake environments. In order to successfully plan access programs detailed geophysical investigations, in particular seismic measurements of water depth, are required to identify suitable drill sites. Prior to the austral summer of 2006/07 measurements of water depths only existed for Subglacial Lake Vostok, and spatial coverage was limited due to the size of the lake. More recently, active source seismic experiments have been carried out over three subglacial lakes, South Pole Lake, Subglacial Lake Ellsworth (SLE) and Subglacial Lake Whillans (SLW). With drilling programs now funded for SLW (access planned for 2011/12) and SLE (access planned for 2012/13) we present results from the geophysical experiments at SLE and SLW to allow the identification of primary drill sites. The two lakes are very different. Geophysical results from SLE suggest that the lake is over 155 m deep and has been a stable system for much of the Holocene. We propose that in order to optimize the chances of successful access and sampling, the entry site should be located in an area with a melting interface near the centre of the lake where water depths are in the order of 100 m. This is away from the down-lake end which shows a higher possibility for basal freezing, with the consequent risk to equipment deployment and retrieval. In contrast, SLW is characterized by dynamic filling and draining over short (2-3 year periods) and most likely has a shallow water column (currently estimated to be in the order of 5-10 m). We suggest that the most suitable location for access will be the centre of the elevation change anomaly recorded over the lake. This point is near equidistant from the lake shoreline features identified from

  15. Small scale high resolution LiDAR measurements of a subglacial conduit (United States)

    Mankoff, K. D.; Gulley, J.


    We present direct measurements of surface roughness in a sub-glacial conduit system underneath the Rieperbreen Glacier, Svalbard, Norway. Data was collected with a low-cost (129 USD) Microsoft Kinect video game device used as a LIDAR sensor. Surface roughness is a primary control on water flow in rivers, channels, and cave conduit systems and understanding the effects of surface roughness on water flow has been problematic due to lack of direct measurements of roughness in natural systems. We use the ice scallop dimensions to derive flow velocity and explore implications of the changing roughness parameters as the cave grows and shrinks.

  16. Observations and modelling of subglacial discharge and heat transport in Godthåbsfjord (Greenland, 64 °N) (United States)

    Bendtsen, Jørgen; Mortensen, John; Rysgaard, Søren


    had a minor dynamical effect on the fjord circulation. However, mixing of bottom water by subglacial discharge also brings large amounts of nutrients to the surface and estimates of the potential nutrient transport show that this may have a significant impact on the biological production in front of tidewater outlet glaciers. Related publications: Bendtsen, J., Mortensen, J., Lennert, K. and S. Rysgaard (2015), Heat sources for glacial ice melt in a West Greenland tidewater outlet glacier fjord: the role of subglacial freshwater discharge, Geophys. Res. Lett., 42, doi:10.1002/2015GL063846. Bendtsen, J., Mortensen, J., and Rysgaard, S. (2015), Modelling subglacial discharge and its influence on ocean heat transport in Arctic fjords, Ocean Dynamics, 65, 1535-1546, 10.1007/s10236-015-0883-1. Mortensen, J., J. Bendtsen, K. Lennert, and S. Rysgaard (2014), Seasonal variability of the circulation system in a west Greenland tidewater outlet glacier fjord, Godthåbsfjord (64°N), J. Geophys. Res. Earth Surf., 119, 2591-2603, doi:10.1002/2014JF003267. Mortensen, J., Bendtsen, J., Motyka, R. J., Lennert, K., Truffer, M., Fahnestock, M. and S. Rysgaard (2013), On the seasonal freshwater stratification in the proximity of fast-flowing tidewater outlet glaciers in a sub-Arctic sill fjord. J. Geophys. Res. 118, 1-14, doi:10.1002/jgrc.20134.

  17. Field validation of specific ecotoxicological tools for aquatic systems impacted with acid mine drainage

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, I.; Goncalves, F.; Nogueira, A.; Soares, A.M.V.M.; Ribeiro, R. [Instituto do Ambiente e Vida, Coimbra (Portugal). Departamento de Zoologia da Universidade de Coimbra


    Acid mine drainage (AMD) is characterised by very low pH and high heavy metal concentrations. Serious ecotoxicological effects, often leading to the complete disruption of the ecosystem, can be observed at the regions suffering this kind of contamination. Those effects can be caused either by low pH itself or by other contaminants that emerge with water acidification (mobilisation and increased solubility of heavy metals). The discrimination between the toxicity due to each of these two factors is not possible with the existing toxicity tests; the addition of chelating agents or serial dilution methods seriously alter the chemical and physical properties of the effluent. A toxicity test, based on the survival time of Ceriodaphnia dubia (Crustacea, Cladocera) neonates exposed to the unchanged effluent was developed and field validated, on an AMD contaminated site. 28 refs.

  18. Characterization of Microbial Communities in Coal Mine Drainage Treatment Systems With Elevated Manganese (United States)

    Tan, H.; Zhang, G.; Burgos, W.


    Sediment samples were collected from two coal mine drainage treatment sites in western Pennsylvania. Both of the sites use constructed limestone beds to passively treat acidic coal mine drainage containing elevated manganese (Mn). Site #1 has influent manganese of 150 mg/L and effluent manganese between 40-100 mg/L. Site #2 has influent manganese of 20 mg/L and effluent manganese of less than 0.5 mg/L. Large quantities of black crusts were deposited throughout the beds at both sites. X-ray diffraction showed these crusts constituted of buserite, which is a layered structure manganese oxide mineral. Both culture-dependent and nucleic acid- based techniques were used to characterize the bacterial and fungal communities in these beds. 16S rRNA gene analysis showed that bacterial communities were very diverse and included Cyanobacter, Proteobacteria, Bacteroidete, Planctomyceta, Acidobacter, Actinobacter and Gemmatimonade taxa. The archaeal diversity was lower and most sequences were related to uncultivated species. Two Mn-oxidizing fungi strains were isolated from one of the sites. One of the fungi is capable of oxidizing Mn(II) at both low and netural pH (3-7) while the other fungi can only oxidze Mn(II) at circumneutral pH. 18S rRNA gene analysis showed the low pH Mn-oxidizing fungus was closely related to Menispora tortuosa, Chaetosphaeria curvispora and Kionochaeta spissa, and the circumneutral Mn-oxidizing fungus was closely related to Myrothecium verrucaria, Didymostilbe echinofibrosa and Myrothecium roridum.

  19. Learning from the operation, pathology and maintenance of a bioretention system to optimize urban drainage practices. (United States)

    de Macedo, Marina Batalini; Rosa, Altair; do Lago, César Ambrogi Ferreira; Mendiondo, Eduardo Mario; de Souza, Vladimir Caramori Borges


    LID practices for runoff control are increasingly being used as an integrated solution in urban drainage, helping to achieve hydrological balance close to the pre-urbanized period and decrease the diffuse pollution transported to urban rivers. Regarding bioretention, there is already broad knowledge about the detention of peak flows and their treatment capacity for many pollutants. However, there are still few field studies in microdrainage scale, which analyze the actual operation of these devices and raise common problems found, especially in subtropical climate. Therefore, this study aims to show what was learnt from the field operation of a bioretention cell on a micro-drainage scale, located in an urban catchment of a Brazilian city, suggesting maintenance actions as adaptations to the pathologies found. Five rainy events were monitored during the dry season, in order to carry out a preliminary analysis for critical conditions in terms of maintenance and diffuse pollution accumulation. From the first water balance results, low storage and low infiltration capacity of the soil were found as main pathologies. They led to a great amount of runoff passing directly through the cell surface and at a high velocity, resulting in soil erosion and low water retention efficiency. To overcome these problems, some structural adaptations were made over the cell, highlighting the semi-direct injection. The maintenance and adaptations proposed were suitable to avoid the erosion process, increasing the storage and improving the water retention efficiency in bioretention. They should be considered from the very initial stages, to using sites with low permeability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Drenaje suplementario del sistema venoso superficial en colgajos pediculados Supplementary drainage of superficial venous system in pedicled flaps

    Directory of Open Access Journals (Sweden)

    A. Fernández García


    Full Text Available Los colgajos pediculados pueden sufrir edema y congestión debido a que su drenaje a trevés del sistema venoso superfical es imposible y el flujo hacia el sistema profundo a nivel del pedículo es precario. Esta situación suele evolucionar hacia la necrosis parcial o la pérdida total del colgajo en pocas horas. La apertura del sistema venoso superficial permite el drenaje adecuado de los tejidos transferidos y evita estas complicaciones. Este artículo analiza el papel de las anastomosis microquirúrgicas en el sistema venoso superficial de los colgajos pediculados. Esta técnica permite comunicar el sistema venoso superfical de los tejidos transferidos con el sistema venoso superficial del territorio que rodea al defecto. Presentamos los resultados obtenidos con esta técnica en colgajos de perforante en hélice, colgajos miocutáneos, colgajos neurocutáneos y colgajos fasciograsos volteados.The pedicled flaps can suffer edema and congestion due to the impossibility of drainage toward the superficial venous system and the precarious flow via the deep system at the level of the pedicle. The evolution of this situation is usually partial necrosis or total loss of the flap in a few hours. The opening of the venous superficial system achieves an appropriate drainage of the transfered tissues and avoids these complications. In this article we analyze the role of the microsurgical anastomosis at the level of the superficial venous system of pedicled flaps. This technique allows to communicate the superficial venous system of the transfered tissues with the superficial venous system of the territory around the defect. We report the results with this method in propeller perforator flaps, miocutaneous flaps, neurocutaneous flaps and adipofascial turn over flaps.

  1. Study of the Raveling Resistance of Porous Asphalt Pavements Used in Sustainable Drainage Systems Affected by Hydrocarbon Spills

    Directory of Open Access Journals (Sweden)

    Jorge Rodriguez-Hernandez


    Full Text Available Permeable pavements are one of the most commonly-used sustainable drainage systems (SuDS in urban areas for managing stormwater runoff problems. Porous asphalt is widely used in surface layers of permeable pavement systems, where it can suffer from accidental oil spills from vehicles. Oil spills affect bituminous mixes through the solvent action of the hydrocarbons on the bitumen, reducing the raveling resistance of asphalt pavements. In order to assess the raveling resistance in porous asphalt pavements, the Cantabro abrasion test was performed on 200 test samples after applying controlled oil spills. Three different types of binders were used: conventional bitumen, polymer-modified bitumen and special fuel-resistant bitumen. After analyzing the results, it was concluded that the most suitable bitumen to protect against oil leakages is the polymer-modified one, which is far better than the other two types of bitumen tested.

  2. Acid Mine Drainage Research in Gauteng Highlighting Impacts on Infrastructure and Innovation of Concrete-Based Remedial Systems (United States)

    Diop, S.; Ekolu, S.; Azene, F.


    Acid mine drainage (AMD) is presently one of the most important environmental problems in in the densely populated Gauteng Province, South Africa. The threat of acid mine drainage has demanded short-term interventions (some of which are being implemented by government) but more importantly sustainable long-term innovative solutions. There have been moments of public apprehension with some media reports dubbing the current scenario as a future 'nightmare of biblical proportions' and 'South Africa's own Chernobyl' that could cause dissolving of concrete foundations of buildings and reinforcement steel, leading to collapse of structures. In response to the needs of local and provincial authorities, this research was conducted to (1) generate scientific understanding of the effects of AMD on infrastructure materials and structures, and (2) propose innovative long-term remedial systems based on cementitious materials for potential AMD treatment applications of engineering scale. Two AMD solutions from the goldfields and two others from the coalfields were used to conduct corrosion immersion tests on mild steel, stainless steel, mortars, pastes and concretes. Results show that AMD water from the gold mines is more corrosive than that from the coal mines, the corrosion rate of the former being about twice that of the latter. The functionality of metal components of mild steel can be expected to fail within one month of exposure to the mine water. The investigation has also led to development of a pervious concrete filter system of water-cement ratio = 0.27 and cement content = 360 kg/m3, to be used as a permeable reactive barrier for AMD treatment. Early results show that the system was effective in removing heavy metal contaminants with removal levels of 30% SO4, 99% Fe, 50-83% Mn, 85% Ca, and 30% TDS. Further work is on-going to improve and optimise the system prior to field demonstration studies.

  3. Advances in modelling subglacial lakes and their interaction with the Antarctic ice sheet. (United States)

    Pattyn, Frank; Carter, Sasha P; Thoma, Malte


    Subglacial lakes have long been considered hydraulically isolated water bodies underneath ice sheets. This view changed radically with the advent of repeat-pass satellite altimetry and the discovery of multiple lake discharges and water infill, associated with water transfer over distances of more than 200 km. The presence of subglacial lakes also influences ice dynamics, leading to glacier acceleration. Furthermore, subglacial melting under the Antarctic ice sheet is more widespread than previously thought, and subglacial melt rates may explain the availability for water storage in subglacial lakes and water transport. Modelling of subglacial water discharge in subglacial lakes essentially follows hydraulics of subglacial channels on a hard bed, where ice sheet surface slope is a major control on triggering subglacial lake discharge. Recent evidence also points to the development of channels in deformable sediment in West Antarctica, with significant water exchanges between till and ice. Most active lakes drain over short time scales and respond rapidly to upstream variations. Several Antarctic subglacial lakes exhibit complex interactions with the ice sheet due to water circulation. Subglacial lakes can therefore-from a modelling point of view-be seen as confined small oceans underneath an imbedded ice shelf. © 2015 The Author(s).

  4. Geology and environments of subglacial Lake Vostok. (United States)

    Leitchenkov, German L; Antonov, Anton V; Luneov, Pavel I; Lipenkov, Vladimir Ya


    The reconstruction of the geological (tectonic) structure and environments of subglacial Lake Vostok is based on geophysical surveys and the study of mineral particles found in cores of accreted ice and frozen lake water (sampled after the lake was unsealed). Seismic reflection and refraction investigations conducted in the southern part of Lake Vostok show very thin (200-300 m) sedimentary cover overlying a crystalline basement. Most of this thin veneer is thought to have been deposited during temperate-glacial conditions in Oligocene to Middle Miocene time (ca 34-14 Ma). The composition of the lake-bottom sediments can be deduced from mineral inclusions found in cores of accreted ice. Inclusions are represented by soft aggregates consisting mainly of clay-mica minerals and micrometre-sized quartz grains. Some of these inclusions contain subangular to semi-rounded rock clasts (siltstones and sandstones) ranging from 0.3 to 8 mm in size. In total, 31 zircon grains have been identified in two rock clasts and dated using SHRIMP-II. The ages of the studied zircons range from 0.6 to 2.0 Ga with two distinct clusters between 0.8 and 1.15 Ga and between 1.6 and 1.8 Ga. Rock clasts obviously came from the western lake shore, which is thus composed of terrigenous strata with an age of not older than 600 Ma. The sedimentary nature of the western lake shore is also confirmed by seismic refraction data showing seismic velocities there of 5.4-5.5 km s(-1) at the bedrock surface. After Lake Vostok was unsealed, its water (frozen and sampled next season) was also studied with scanning electron microscopy and X-ray microprobe analysis. This study showed the existence of calcium carbonate and silica microparticles (10-20 μm across) in frozen water. © 2015 The Author(s).

  5. Image-guided system endoscopic drainage of orbital abscess caused by methicillin-resistant Staphylococcus aureus in an infant

    Directory of Open Access Journals (Sweden)

    Tan Chai-Lee


    Conclusion: Aggressive management of orbital abscesses in infants is mandatory. Image-guided endoscopic orbital drainage offers precise visualization and a safer technique in a relatively smaller orbit.

  6. Lake Vostok: From a Continental Margin to a Subglacial Lake (United States)

    Studinger, M.; Bell, R. E.; KArner, G. D.; Tikku, A. A.; Levin, V.; Raymond, C. A.; Lerner-Lam, A.


    Subglacial ecosystems, in particular subglacial lakes, represent the most oligothrophic environments on Earth. The geologic origin of Lake Vostok is a critical boundary condition for both the stability of the lake and energy fluxes into the lake. Microbial life may use geothermal energy, similar to life discovered at deep sea hydrothermal vents. Significant geothermal anomalies are often associated with active faulting. The topographic depression which forms the craddle for Lake Vostok is part of a regional tectonic structure ranging from the Gamburtsev Subglacial Mountains to the Aurora Subglacial Basin. This geologic boundary was formed by emplacement of a thrust sheet from the east over a pre-existing passive continental margin beneath the present-day Lake Vostok. No data exist to directly date either the timing of passive margin formation or the subsequent crustal shortening. Minor extensional reactivation of the thrust sheet explains a simple mechanism to explain the formation of the Lake Vostok basin. The steep slopes bounding this depression are likley being fault-controlled. Our recent discovery of microseismic activity suggest that this faults might be active and could act as conduits for convecting fluids. The tectonic processes can have an important influence on the ecosystem within the lake.

  7. Ice-dammed lake drainage in west Greenland: Drainage pattern and implications on ice flow and bedrock motion

    DEFF Research Database (Denmark)

    Kjeldsen, Kristian Kjellerup; Khan, Shfaqat Abbas; Bjørk, Anders


    Ice-dammed lakes drain frequently in Greenland, but the impacts of these events differ between sites. Here we study the quasi-cyclic behavior of the ~40 km2 Lake Tininnilik in west Greenland and its impact on ice flow and crustal deformation. Data reveal rapid drainage of 1.83 ± 0.17 km3 of water...... of surface loading in addition to ice mass change, when assessing glacial isostatic adjustment or elastic rebound using geodetic data. Moreover, the results illustrates a linkage between subglacial discharge and ice surface velocity, important for assessing ice flux, and thus mass balance, in a future...

  8. Subglacial sediment mechanics investigated by computer simulation of granular material (United States)

    Damsgaard, A.; Egholm, D. L.; Tulaczyk, S. M.; Piotrowski, J. A.; Larsen, N. K.; Siegfried, M. R.; Beem, L.; Suckale, J.


    The mechanical properties of subglacial sediments are known to directly influence the stability of ice streams and fast-moving glaciers, but existing models of granular sediment deformation are poorly constrained. In addition, upscaling to generalized mathematical models is difficult due to the mechanical nonlinearity of the sediment, internal porosity changes during deformation, and associated structural and kinematic phase transitions. In this presentation, we introduce the Discrete Element Method (DEM) for particle-scale granular simulation. The DEM is fully coupled with fluid dynamics. The numerical method is applied to better understand the mechanical properties of the subglacial sediment and its interaction with meltwater. The computational approach allows full experimental control and offers insights into the internal kinematics, stress distribution, and mechanical stability. During confined shear with variable pore-water pressure, the sediment changes mechanical behavior, from stick, to non-linear creep, and unconstrained failure during slip. These results are contrary to more conventional models of plastic or (non-)linear viscous subglacial soft-bed sliding. Advection of sediment downstream is pressure dependent, which is consistent with theories of unstable bed bump growth. Granular mechanics prove to significantly influence the geometry and hydraulic properties of meltwater channels incised into the subglacial bed. Current models assume that channel bed erosion is balanced by linear-viscous sediment movement. We demonstrate how channel flanks are stabilized by the sediment frictional strength. Additionally, sediment liquefaction proves to be a possible mechanism for causing large and episodic sediment transport by water flow. Though computationally intense, our coupled numerical method provides a framework for quantifying a wide range of subglacial sediment-water processes, which are a key unknown in our ability to model the future evolution of ice

  9. A three-dimensional analysis of the endolymph drainage system in Ménière disease. (United States)

    Monsanto, Rafael da Costa; Pauna, Henrique F; Kwon, Geeyoun; Schachern, Patricia A; Tsuprun, Vladimir; Paparella, Michael M; Cureoglu, Sebahattin


    To measure the volume of the endolymph drainage system in temporal bone specimens with Ménière disease, as compared with specimens with endolymphatic hydrops without vestibular symptoms and with nondiseased specimens STUDY DESIGN: Comparative human temporal bone analysis. We generated three-dimensional models of the vestibular aqueduct, endolymphatic sinus and duct, and intratemporal portion of the endolymphatic sac and calculated the volume of those structures. We also measured the internal and external aperture of the vestibular aqueduct, as well as the opening (if present) of the utriculoendolymphatic (Bast's) valve and compared the measurements in our three study groups. The volume of the vestibular aqueduct and of the endolymphatic sinus, duct, and intratemporal endolymphatic sac was significantly lower in the Ménière disease group than in the endolymphatic hydrops group (P <.05). The external aperture of the vestibular aqueduct was also smaller in the Ménière disease group. Bast's valve was open only in some specimens in the Ménière disease group. In temporal bones with Ménière disease, the volume of the vestibular aqueduct, endolymphatic duct, and intratemporal endolymphatic sac was lower, and the external aperture of the vestibular aqueduct was smaller as compared with bones from donors who had endolymphatic hydrops without vestibular symptoms and with nondiseased bones. The open status of the Bast's valve in the Ménière disease group could be secondary to higher retrograde endolymph pressures caused by smaller drainage systems. These anatomic findings could correlate with the reason that some patients with hydrops develop clinical symptoms, whereas others do not. N/A Laryngoscope, 127:E170-E175, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

  10. Clean access, measurement, and sampling of Ellsworth Subglacial Lake: A method for exploring deep Antarctic subglacial lake environments (United States)

    Siegert, Martin J.; Clarke, Rachel J.; Mowlem, Matt; Ross, Neil; Hill, Christopher S.; Tait, Andrew; Hodgson, Dominic; Parnell, John; Tranter, Martyn; Pearce, David; Bentley, Michael J.; Cockell, Charles; Tsaloglou, Maria-Nefeli; Smith, Andy; Woodward, John; Brito, Mario P.; Waugh, Ed


    Antarctic subglacial lakes are thought to be extreme habitats for microbial life and may contain important records of ice sheet history and climate change within their lake floor sediments. To find whether or not this is true, and to answer the science questions that would follow, direct measurement and sampling of these environments are required. Ever since the water depth of Vostok Subglacial Lake was shown to be >500 m, attention has been given to how these unique, ancient, and pristine environments may be entered without contamination and adverse disturbance. Several organizations have offered guidelines on the desirable cleanliness and sterility requirements for direct sampling experiments, including the U.S. National Academy of Sciences and the Scientific Committee on Antarctic Research. Here we summarize the scientific protocols and methods being developed for the exploration of Ellsworth Subglacial Lake in West Antarctica, planned for 2012-2013, which we offer as a guide to future subglacial environment research missions. The proposed exploration involves accessing the lake using a hot-water drill and deploying a sampling probe and sediment corer to allow sample collection. We focus here on how this can be undertaken with minimal environmental impact while maximizing scientific return without compromising the environment for future experiments.

  11. Coupling autotrophic sulfide mineral weathering with dolomite dissolution in a subglacial ecosystem (United States)

    Boyd, E. S.; Hamilton, T. L.; Havig, J. R.; Lange, R.; Murter, E.; Skidmore, M. L.; Peters, J.; Shock, E.


    and abundant autotrophic community in the RG subglacial environment with the dominant population exhibiting close affiliation with the sulfide mineral oxidizing autotroph Sideroxydans lithoautotrophicus. Analysis of dissolved solutes in late season glacial meltwaters indicate that the production of sulfate through sulfide mineral oxidation is closely coupled with increases in the concentration of calcium, magnesium, and carbonate ions, suggesting that the oxidation of pyrite is closely coupled with the dissolution of dolomite, a dominant carbonate mineral in the local bedrock. Thus, microbially mediated sulfide mineral weathering in subglacial systems provides a conduit for transport of nutrients to downstream freshwater and marine systems. Collectively, these results underscore the contribution of cold and dark subglacial environments to global biogeochemical cycles, both today and in Earth's past, and demonstrate the potential role of autotrophic microorganisms in sustaining subglacial microbial communities over geologic time periods.

  12. Seismicity and Subglacial Hydrological Processes During Early Melt Season, Engabreen, Norway (United States)

    Moore, P. L.; Winberry, J.; Christianson, K.; Iverson, N. R.; Anandakrishnan, S.; Jackson, M.; Cohen, D. O.


    A broad array of mechanical and seismic instrumentation was deployed during May 2011 in subglacial tunnels beneath Engabreen, an outlet glacier of the Svartisen ice cap in northern Norway. Following a warm spell, increased melt supply to the glacier bed prompted several episodes of transient ice uplift and establishment of a more efficient basal hydraulic system. In each event, hydrological adjustment was accompanied by three distinct seismic sources, two of which have not been previously documented in glacial environments. High-frequency impulsive events with dominant Rayleigh-wave energy increased their rate-of-occurrence immediately prior to an abrupt change in basal water pressure and normal stress. These events are inferred represent propagation of water-filled crevasses permitting meltwater access to the bed. Ultra-long period (ULP, hydraulic jacking. During recovery of basal water pressure, vertical ULP deflections were correlated with increases in basal water flux and doubling of local subglacial seismic noise. The increase in seismic noise may represent turbulent flow and bedload sediment transport through newly-opened subglacial meltwater passages. The vertical ULP signal therefore likely reflects meltwater-forced uplift of ice. Surprisingly, although there was direct evidence that jacking activated frictional slip at the bed, there was no clear seismic expression of slip. Thus, broadband seismometers appear to have captured the transit of meltwater through crevasses, into isolated pockets at the glacier bed and then, by promoting ice uplift, draining though newly-established meltwater passages along the bed. Similar seismic sources could be detected elsewhere with strategically-located broadband seismic instrumentation, providing a means of remotely monitoring the hydrological processes that control ice motion.

  13. Fluid flow along venous adventitia in rabbits: is it a potential drainage system complementary to vascular circulations?

    Directory of Open Access Journals (Sweden)

    Hong-yi Li

    Full Text Available BACKGROUND: Our previous research and other studies with radiotracers showed evidence of a centripetal drainage pathway, separate from blood or lymphatic vessels, that can be visualized when a small amount of low molecular weight tracer is injected subcutaneously into a given region on skin of humans. In order to further characterize this interesting biological phenomenon, animal experiments are designed to elucidate histological and physiologic characteristics of these visualized pathways. METHODS: Multiple tracers are injected subcutaneously into an acupuncture point of KI3 to visualize centripetal pathways by magnetic resonance imaging or fluorescein photography in 85 healthy rabbits. The pathways are compared with venography and indirect lymphangiography. Fluid flow through the pathways is observed by methods of altering their hydrated state, hydrolyzing by different collagenases, and histology is elucidated by optical, fluorescein and electron microscopy. RESULTS: Histological and magnetic imaging examinations of these visualized pathways show they consist of perivenous loose connective tissues. As evidenced by examinations of tracers' uptake, they appear to function as a draining pathway for free interstitial fluid. Fluorescein sodium from KI3 is found in the pathways of hind limbs and segments of the small intestines, partial pulmonary veins and results in pericardial effusion, suggesting systematical involvement of this perivenous pathway. The hydraulic conductivity of these pathways can be compromised by the collapse of their fiber-rich beds hydrolyzed by either of collagenase type I, III, IV or V. CONCLUSIONS: The identification of pathways comprising perivenous loose connective tissues with a high hydraulic conductivity draining interstitial fluid in hind limbs of a mammal suggests a potential drainage system complementary to vascular circulations. These findings may provide new insights into a systematically distributed collagenous

  14. Provenance and drainage system of the Early Cretaceous volcanic detritus in the Himalaya as constrained by detrital zircon geochronology

    Directory of Open Access Journals (Sweden)

    Xiu-Mian Hu


    Full Text Available The age range of the major intra-plate volcanic event that affected the northern Indian margin in the Early Cretaceous is here defined precisely by detrital zircon geochronology. U–Pb ages of Early Cretaceous detrital zircons found in the Cretaceous to the Paleocene sandstones cluster mainly between 142 Ma and 123 Ma in the northern Tethys Himalayan unit, and between 140 Ma and 116 Ma in the southern Tethys Himalayan unit. The youngest and oldest detrital zircons within this group indicate that volcanism in the source areas started in the latest Jurassic and ended by the early Albian. Stratigraphic data indicate that volcaniclastic sedimentation began significantly earlier in southern Tibet (Tithonian than in Nepal (Valanginian, and considerably later in Spiti and Zanskar (Aptian/Albian to the west. This apparent westward migration of magmatism was explained with progressive westward propagation of extensional/transtensional tectonic activity and development of fractures cutting deeply across the Indian continental margin crust. However, detrital zircon geochronology provides no indication of heterochroneity in magmatic activity in the source areas from east to west, and thus lends little support to such a scenario. Westward migration of volcaniclastic sedimentation may thus reflect instead the westward progradation of major drainage systems supplying volcanic detritus sourced from the same volcanic centers in the east. Development of multiple radial drainage away from the domal surface uplift associated with magmatic upwelling, as observed for most large igneous provinces around the world, may also explain why U–Pb ages of detrital zircons tend to cluster around 133–132 Ma (the age of the Comei igneous province in Tethys Himalayan units, but around 118–117 Ma (the age of the Rajmahal igneous province in Lesser Himalayan units.

  15. Present morphoclimate and morphodynamics in the boreal Homla drainage basin system (Trøndelag, middle Norway) (United States)

    Beylich, Achim A.


    It is generally accepted that ongoing and future climate change will cause major changes in Earth surface systems and environments. From a geomorphological point of view, it is accordingly of increasing importance to obtain a better understanding of the relationships between contemporary geomorphological processes and present-day climatic conditions to come to more reliable assessments of the possible geomorphological effects of climate change. Until recently, the present-day climate has often only been characterized by monthly and annual means or sum values of wind speed, air temperature and precipitation. As most geomorphological surface processes consist of discrete events which are only partly correlated to these meteorological means or sum values, there is an obvious need for an additional approach of statistical analysis of meteorological data. In this study the "morphoclimate" of the Homla drainage basin situated in a boreal environment in Trøndelag in middle Norway is analyzed. "Morphoclimate" according to Ahnert (e.g., 1982) is specially related to geomorphological needs and, in this sense, is defined as the totality of those climatic characteristics of an area that influence the type, frequency, duration and intensity of the exogenic geomorphologic processes in this area. The statistical method primarily used in this context is the magnitude-frequency analysis. Particular emphasis is on (i) the frequencies or recurrence intervals of meteorological events of given magnitudes, and (ii) the frequencies of geomorphologically important thresholds. Aspects of the current wind, temperature and precipitation regimes which control the type, frequency, duration and intensity of the contemporary denudational surface processes as well as the sedimentary budget in the selected study area are presented. Runoff in the boreal Homla drainage basin is occurring year-round and the contemporary morphodynamics are altogether characterized by a clear dominance of chemical

  16. Unveiling subglacial geology and crustal architecture in the Recovery frontier of East Antarctica with recent aeromagnetic and airborne gravity imaging (United States)

    Ferraccioli, F.; Forsberg, R.; Jordan, T. A.; Matsuoka, K.; Olsen, A.; King, O.; Ghidella, M.


    underlie the giant Recovery subglacial lakes and compare these with the rift basins of the East Antarctic Rift System, which have been proposed to host other major subglacial lakes, such as Lake Vostok, Lake 90E and Lake Sovetskaya.

  17. Hydrological Modeling of Storm Water Drainage System due to Frequent and Intense Precipitation of Dhaka city using Storm Water Management Model (SWMM) (United States)

    Hossain, S., Jr.


    Rainfall induced flooding during rainy season is a regular phenomenon in Dhaka City. Almost every year a significant part of the city suffers badly with drainage congestion. There are some highly dense areas with lower ground elevation which submerge under water even with an intense precipitation of few hours. The higher areas also suffer with the drainage problem due to inadequate maintenance of the system and encroachment or illegal filling up of the drainage canals and lakes. Most part of the city suffered from long term urban flooding during historical extreme rainfall events in September 2004, 2007 and July 2009. The situation is likely to worsen in the future due to Climate Change, which may lead to more frequent and intense precipitation. To assess the major and minor drainage systems and elements of the urban basins using the hydrodynamic modelling and, through this, identifying the flooding events and areas, taking into account the current situation and future flood or drainage scenarios. Stormwater modeling has a major role in preventing issues such as flash floods and urban water-quality problems. Stormwater models of a lowered spatial resolution would thus appear valuable if only their ability to provide realistic results could be proved. The present scenario of urban morphology of Dhaka city and existing drainage system is complex for hydrological and hydrodynamic modeling. Furthermore limitations of background data and uncertain future urban scenarios may confine the potential outputs of a model. Although several studies were carried out including modeling for drainage master planning, a detail model for whole DAP (Detaile Area Plan) of Dhaka city area is not available. The model developed under this study is covering the existing drainage system in the study area as well as natural flows in the fringe area. A good number of models are available for hydrological and hydraulic analysis of urban areas. These are MIKE 11, MOUSE, HEC-RAS, HEC HMS and EPA

  18. Coordinating rule-based and system-wide model predictive control strategies to reduce storage expansion of combined urban drainage systems: The case study of Lundtofte, Denmark

    DEFF Research Database (Denmark)

    Meneses, Elbys Jose; Gaussens, Marion; Jakobsen, Carsten


    The environmental benefits of combining traditional infrastructure solutions for urban drainage (increasing storage volume) with real time control (RTC) strategies were investigated in the Lundofte catchment in Denmark, where an expensive traditional infrastructure expansion is planned to comply...... with environmental requirements. A coordinating, rule-based RTC strategy and a global, system-wide risk-based dynamic optimization strategy (model predictive control), were compared using a detailed hydrodynamic model. RTC allowed a reduction of the planned storage volume by 21% while improving the system...

  19. Acid mine drainage (United States)

    Bigham, Jerry M.; Cravotta, Charles A.


    Acid mine drainage (AMD) consists of metal-laden solutions produced by the oxidative dissolution of iron sulfide minerals exposed to air, moisture, and acidophilic microbes during the mining of coal and metal deposits. The pH of AMD is usually in the range of 2–6, but mine-impacted waters at circumneutral pH (5–8) are also common. Mine drainage usually contains elevated concentrations of sulfate, iron, aluminum, and other potentially toxic metals leached from rock that hydrolyze and coprecipitate to form rust-colored encrustations or sediments. When AMD is discharged into surface waters or groundwaters, degradation of water quality, injury to aquatic life, and corrosion or encrustation of engineered structures can occur for substantial distances. Prevention and remediation strategies should consider the biogeochemical complexity of the system, the longevity of AMD pollution, the predictive power of geochemical modeling, and the full range of available field technologies for problem mitigation.

  20. Subsurface recharge to the Tesuque aquifer system from selected drainage basins along the western side of the Sangre de Cristo Mountains near Santa Fe, New Mexico (United States)

    Wasiolek, Maryann


    Water budgets developed for basins of five streams draining the western side of the Sangre de Cristo Mountains in northern New Mexico indicate that subsurface inflow along the mountain front is recharging the Tesuque aquifer system of the Espanola Basin. Approximately 14,700 acre-feet of water per year, or 12.7 percent of average annual precipitation over the mountains, is calculated to leave the mountain block and enter the basin as subsurface recharge from the drainage basins of the Rio Nambe, Rio en Medio, Tesuque Creek, Little Tesuque Creek, and Santa Fe River. About 5,520 acre- feet per year, or about 12 percent of average annual precipitation, is calculated to enter from the Rio Nambe drainage basin; about 1,710 acre- feet per year, or about 15 percent of average annual precipitation, is calculated to enter from the Rio en Medio drainage basin; about 1,530 acre- feet, or about 10 percent of average annual precipi- tation, is calculated to enter from the Tesuque Creek drainage basin; about 1,790 acre-feet, or about 19 percent of average annual precipitation, is calculated to enter from the Little Tesuque Creek drainage basin; and about 4,170 acre-feet per year, or about 12 percent average annual precipitation, is calculated to enter from the Santa Fe River drainage basin. Calculated subsurface recharge values were used to define maximum fluxes permitted along the specified-flux boundary defining the mountain front of the Sangre De Cristo Mountains in a numerical computer model of the Tesuque aquifer system near Santa Fe, New Mexico.

  1. Development of a wireless intra-ocular pressure monitoring system for incorporation into a therapeutic glaucoma drainage implant (United States)

    Kakaday, Tarun; Plunkett, Malcolm; McInnes, Steven; Li, Jim S. Jimmy; Voelcker, Nicolas H.; Craig, Jamie E.


    Glaucoma is a common cause of blindness. Wireless, continuous monitoring of intraocular pressure (IOP) is an important, unsolved goal in managing glaucoma. An IOP monitoring system incorporated into a glaucoma drainage implant (GDI) overcomes the design complexity associated with incorporating a similar system in a more confined space within the eye. The device consists of a micro-electro-mechanical systems (MEMS) based capacitive pressure sensor integrated with an inductor printed directly onto a polyimide printed circuit board (PCB). The device is designed to be incorporated onto the external plate of a therapeutic GDI. The resonance frequency changes as a function of IOP, and is tracked remotely using a spectrum analyzer. A theoretical model for the reader antenna was developed to enable maximal inductive coupling with the IOP sensor implant. Pressure chamber tests indicate that the sensor implant has adequate sensitivity in the IOP range with excellent reproducibility over time. Additionally, we show that sensor sensitivity does not change significantly after encapsulation with polydimethylsiloxane (PDMS) to protect the device from fluid environment. In vitro experiments showed that the signal measured wirelessly through sheep corneal and scleral tissue was adequate indicating potential for using the system in human subjects.

  2. Action research: an appropriate research methodology to develop on-farm drainage systems with farmers with reference to the NRAP Project, Pakistan

    NARCIS (Netherlands)

    Schrevel, A.; Bhutta, M.N.


    In the period up till 2000 the Netherlands Research Assistance Project (NRAP) ran an Action Research programme to develop a drainage system together with farmers in an area suffering from salinity and waterlogging. Executing parties of NRAP were the International Waterlogging and Salinity Research

  3. Response of salt structures to ice-sheet loading: implications for ice-marginal and subglacial processes (United States)

    Lang, Jörg; Hampel, Andrea; Brandes, Christian; Winsemann, Jutta


    During the past decades the effect of glacioisostatic adjustment has received much attention. However, the response of salt structures to ice-sheet loading and unloading is poorly understood. Our study aims to test conceptual models of the interaction between ice-sheet loading and salt structures by finite-element modelling. The results are discussed with regard to their implications for ice-marginal and subglacial processes. Our models consist of 2D plane-strain cross-sections, which represent simplified geological cross-sections from the Central European Basin System. The model layers represent (i) sedimentary rocks of elastoplastic rheology, (ii) a viscoelastic diapir and layer of salt and (iii) an elastoplastic basement. On top of the model, a temporarily variable pressure simulates the advance and retreat of an ice sheet. The durations of the individual loading phases were defined to resemble the durations of the Pleistocene ice advances in northern central Europe. The geometry and rheology of the model layers and the magnitude, spatial distribution and timing of ice-sheet loading were systematically varied to detect the controlling factors. All simulations indicate that salt structures respond to ice-sheet loading. An ice advance towards the diapir causes salt flow from the source layer below the ice sheet towards the diapir, resulting in an uplift of up to +4 m. The diapir continues to rise as long as the load is applied to the source layer but not to the crest of the diapir. When the diapir is transgressed by the ice sheet the diapir is pushed down (up to -36 m) as long as load is applied to the crest of the diapir. During and after ice unloading large parts of the displacement are compensated by a reversal of the salt flow. Plastic deformation of the overburden is restricted to the area immediately above the salt diapir. The displacements after unloading range between -3.1 and +2.7 m. Larger displacements are observed in models with deep-rooted diapirs

  4. Discontinuous drainage systems formed by highland precipitation and ground-water outflow in the Navua Valles and southwest Hadriacus Mons regions, Mars (United States)

    Hargitai, H. I.; Gulick, V. C.; Glines, N. H.


    The Navua Valles are systems of paleodrainages located north of Dao Vallis, which empty into Hellas Planitia, the largest impact basin on Mars. In this study, we mapped and characterized the Navua Valles Region's individual drainage systems, including drainages along the southwestern flank of Hadriacus Mons, and one valley network from the same source as Navua Valles but flowing in the opposite direction. The major drainage systems share morphological characteristics common to both outflow channels and valley networks. The slopes in this region are dissected by two major Navua drainage systems (here Navua A* and B*) and several shorter, sub-parallel valleys formed on the highest gradient (approximately 20 m/km [1.15°]) slopes, at the lowest part of Hellas Basin's rim. The two major drainage systems originate in the highlands, and empty into the basin. Our mapping suggests that water in Navua Valles reached the basin floor in a complicated descent and included several episodes of surface ponding, surface runoff, infiltration, subsurface flow and subsequent outflow. The most prominent channel system, Navua A, forms a repetitive sequence of deep incision into bedrock, followed by a transition into broad channels in erodible materials, and then into unconfined deposits. This successive erosion-transport-deposition sequence continues to repeat along the valley's entire length forming a discontinuous pattern that is consistent with classical fluvial process models. The channels cut into volcanic plains likely emplaced from the formation of Tyrrhenus and Hadriacus Montes. The dendritic source valleys of Navua A originate from the rim of a highland crater while the rest of this subsystem consists of a single, discontinuous channel which is consistent with a single water source zone that likely supplied water for all channels downslope. These drainages may have formed as discontinuous channels, revealing the potential existence of subsurface drainage pathways located

  5. Reversal of benign prostate hyperplasia by selective occlusion of impaired venous drainage in the male reproductive system: novel mechanism, new treatment. (United States)

    Gat, Y; Gornish, M; Heiblum, M; Joshua, S


    The prostate is an androgen-regulated exocrine gland producing over 30% of the noncellular components of the semen and promoting optimal conditions for survival and motility of sperm in the vagina. Benign prostate hyperplasia (BPH) is the most common benign neoplasm in men. Its aetiology is not clear, and therefore, current medical treatments are directed towards the symptoms. Though testosterone is known to be the promoter of prostate cell proliferation, no causal relation between serum testosterone levels and BPH has been found. In this study, we propose a novel and tested pathophysiological mechanism for the evolution of BPH and suggest a tested and effective treatment. We found that in all BPH patients, the one-way valves in the vertically oriented internal spermatic veins are destroyed (clinically manifested as varicocele), causing elevated hydrostatic pressure, some 6-fold greater than normal, in the venous drainage of the male reproductive system. The elevated pressure propagates to all interconnected vessels leading to a unique biological phenomenon: venous blood flows retrograde from the higher pressure in the testicular venous drainage system to the low pressure in the prostatic drainage system directly to the prostate (law of communicating vessels). We have found that free testosterone levels in this blood are markedly elevated, with a concentration of some 130-fold above serum level. Consequently, the prostate is exposed to: (i) increased venous pressure that causes hypertrophy; (ii) elevated concentration of free testosterone causing hyperplasia. We have treated 28 BPH patients using a technique that restores normal pressure in the venous drainage in the male reproductive system. The back-pressure and the back-flow of blood from the testicular to the prostate drainage system were eliminated and, consequently, a rapid reduction in prostate volume and a regression of prostate symptoms took place.

  6. Insurance data as way to evaluate the performance of a sustainable urban drainage system (SUDS) in Augustenborg, Malmö (United States)

    Sörensen, Johanna; Emilsson, Tobias


    Sustainable Urban Drainage Systems (SUDS) has been put forward as a concept to improve stormwater management in urban areas. The damage reduction due to reduced flooding and storm water detention during extreme events is one of many important features of SUDS. As extreme events are rare, few assessments have earlier been made to evaluate the risk reduction. So far, most assessments have been done by hydraulic modelling, rather than analyses based on data from real flood events. In 2014, Malmö was hit with an extreme rainfall event which led to severe flooding in most parts of the city. This event gave an opportunity to evaluate the efficiency of SUDS during extreme events. In this study, flood claim data were analysed to evaluate flood risk reduction by the SUDS system in Augustenborg. Flood claim data were collected from both an insurance company, as well as the water utility company of Malmö for 5 neighbourhoods in close proximity in Malmö. The study uses the Augustenborg neighbourhood as an example of a retrofitted neighbourhood with an open SUDS. Augustenborg (Malmö, Sweden) was retrofitted 15 years ago using a combination of hard infrastructure and naturebased solutions, to alleviate basement flooding, to reduce combined sewer overflows (CSO) and to increase the ecological and aesthetical values of the area. The introduction of ponds, channels and green roofs dramatically changed the appearance of the area and the more or less regular floods were stopped. Augustenborg and its sustainable drainage system was compared with five similar neighbourhoods nearby. The long-term development of reported insurance claims in the selected neighbourhoods showed a reduction of flooding in Augustenborg compared to the nearby areas. Pre- and post-installation data showed a direct effect of the refurbishment with SUDS. Even though a few properties were flooded in Augustenborg, it was shown that the SUDS performed successfully during the extreme storm event that was the most

  7. Exploring Agricultural Drainage's Influence on Wetland and ... (United States)

    Artificial agricultural drainage (i.e. surface ditches or subsurface tile) is an important agricultural management tool. Artificial drainage allows for timely fieldwork and adequate root aeration, resulting in greater crop yields for farmers. This practice is widespread throughout many regions of the United States and the network of artificial drainage is especially extensive in flat, poorly-drained regions like the glaciated Midwest. While beneficial for crop yields, agricultural drains often empty into streams within the natural drainage system. The increased network connectivity may lead to greater contributing area for watersheds, altered hydrology and increased conveyance of pollutants into natural water bodies. While studies and models at broader scales have implicated artificial drainage as an important driver of hydrological shifts and eutrophication, the actual spatial extent of artificial drainage is poorly known. Consequently, metrics of wetland and watershed connectivity within agricultural regions often fail to explicitly include artificial drainage. We use recent agricultural census data, soil drainage data, and land cover data to create estimates of potential agricultural drainage across the United States. We estimate that agricultural drainage in the US is greater than 31 million hectares and is concentrated in the upper Midwest Corn Belt, covering greater than 50% of available land for 114 counties. Estimated drainage values for numerous countie

  8. Microbial sulfur transformations in sediments from Subglacial Lake Whillans

    Directory of Open Access Journals (Sweden)

    Alicia M Purcell


    Full Text Available Diverse microbial assemblages inhabit subglacial aquatic environments. While few of these environments have been sampled, data reveal that subglacial organisms gain energy for growth from reduced minerals containing nitrogen, iron, and sulfur. Here we investigate the role of microbially mediated sulfur transformations in sediments from Subglacial Lake Whillans (SLW, Antarctica, by examining key genes involved in dissimilatory sulfur oxidation and reduction. The presence of sulfur transformation genes throughout the top 34 cm of SLW sediments changes with depth. SLW surficial sediments were dominated by genes related to known sulfur-oxidizing chemoautotrophs. Sequences encoding the adenosine-5’-phosphosulfate (APS reductase gene, involved in both dissimilatory sulfate reduction and sulfur oxidation, were present in all samples and clustered into 16 distinct OTUs. The majority of APS reductase sequences (74% clustered with known sulfur oxidizers including those within the Sideroxydans and Thiobacillus genera. Reverse-acting dissimilatory sulfite reductase (rDSR and 16S rRNA gene sequences further support dominance of Sideroxydans and Thiobacillus phylotypes in the top 2 cm of SLW sediments. The SLW microbial community has the genetic potential for sulfate reduction which is supported by experimentally measured low rates (1.4 pmol cm-3d-1 of biologically mediated sulfate reduction and the presence of APS reductase and DSR gene sequences related to Desulfobacteraceae and Desulfotomaculum. Our results also infer the presence of sulfur oxidation, which can be a significant energetic pathway for chemosynthetic biosynthesis in SLW sediments. The water in SLW ultimately flows into the Ross Sea where intermediates from subglacial sulfur transformations can influence the flux of solutes to the Southern Ocean.


    Directory of Open Access Journals (Sweden)

    Ireneusz Cymes


    Full Text Available The study included groundwater outflow drainage systems and collected in the pond located at the agricultural use area in the portion of the drainage facility Lidzbark Warminski located on the Sępopolska Plain. The study was performed in two periods: the first one was in 1998–2000 (just after was made drainage, in which the discussed area was used as pasture, and the second in 2008–2010, in which after plowed of the soil was cultivated winter wheat. The aim of the study was to determine changes in water quality after the change of the way of land use. Examinations showed that as a result of the change of the way of using the area and ceasing of mineral fertilizing in waters of the pond was a reduction in the concentrations of the most mineral components, but an increase of pH reaction and concentrations of potassium, magnesium of sulfates and bicarbonates. In groundwaters observed increased the content of concentrations of mineral forms of nitrogen, phosphatic phosphorus, potassium, magnesium, general iron and bicarbonates, and a reduction in the concentrations of calcium, sodium, sulfates and chlorides. However in the water which outflow from drainage pipelines system from the research area was an increase of concentrations most of the determined substances, apart from ammonia nitrogen and chlorides.

  10. Constraining local subglacial bedrock erosion rates with cosmogenic nuclides (United States)

    Wirsig, Christian; Ivy-Ochs, Susan; Christl, Marcus; Reitner, Jürgen; Reindl, Martin; Bichler, Mathias; Vockenhuber, Christof; Akcar, Naki; Schlüchter, Christian


    The constant buildup of cosmogenic nuclides, most prominently 10Be, in exposed rock surfaces is routinely employed for dating various landforms such as landslides or glacial moraines. One fundamental assumption is that no cosmogenic nuclides were initially present in the rock, before the event to be dated. In the context of glacially formed landscapes it is commonly assumed that subglacial erosion of at least a few meters of bedrock during the period of ice coverage is sufficient to remove any previously accumulated nuclides, since the production of 10Be ceases at a depth of 2-3 m. Insufficient subglacial erosion leads to overestimation of surface exposure ages. If the time since the retreat of the glacier is known, however, a discordant concentration of cosmogenic nuclides delivers information about the depth of subglacial erosion. Here we present data from proglacial bedrock at two sites in the Alps. Goldbergkees in the Hohe Tauern National Park in Austria and Gruebengletscher in the Grimsel Pass area in Switzerland. Samples were taken inside as well as outside of the glaciers' Little Ice Age extent. Measured nuclide concentrations are analyzed with the help of a MATLAB model simulating periods of exposure or glacial cover of user-definable length and erosion rates.

  11. Subglacial discharge-driven renewal of tidewater glacier fjords (United States)

    Carroll, Dustin; Sutherland, David A.; Shroyer, Emily L.; Nash, Jonathan D.; Catania, Ginny A.; Stearns, Leigh A.


    The classic model of fjord renewal is complicated by tidewater glacier fjords, where submarine melt and subglacial discharge provide substantial buoyancy forcing at depth. Here we use a suite of idealized, high-resolution numerical ocean simulations to investigate how fjord circulation driven by subglacial plumes, tides, and wind stress depends on fjord width, grounding line depth, and sill height. We find that the depth of the grounding line compared to the sill is a primary control on plume-driven renewal of basin waters. In wide fjords the plume exhibits strong lateral recirculation, increasing the dilution and residence time of glacially-modified waters. Rapid drawdown of basin waters by the subglacial plume in narrow fjords allows for shelf waters to cascade deep into the basin; wide fjords result in a thin, boundary current of shelf waters that flow toward the terminus slightly below sill depth. Wind forcing amplifies the plume-driven exchange flow; however, wind-induced vertical mixing is limited to near-surface waters. Tidal mixing over the sill increases in-fjord transport of deep shelf waters and erodes basin stratification above the sill depth. These results underscore the first-order importances of fjord-glacier geometry in controlling circulation in tidewater glacier fjords and, thus, ocean heat transport to the ice.

  12. What controls the explosivity of subglacial rhyolite in Iceland? (United States)

    Owen, J.; Tuffen, H.; McGarvie, D. W.


    The eruption controls of subglacial rhyolite are poorly understood but this is of key importance in mitigating hazards. In subaerial rhyolite eruptions the pre-eruptive volatile content and degassing path are considered to be the primary controls of explosivity, but is this also the case when rhyolitic eruptions occur under ice? We present the first pre-eruptive volatile content and degassing path data for subglacial rhyolite eruptions, comparing three edifices of contrasting eruption style from the Torfajökull complex in South Iceland[1]. Volatile concentrations were measured using infra-red spectroscopy (FTIR) and Secondary Ion Mass Spectroscopy (SIMS). SE Rauðfossafjöll is a large volume (~1 km3) explosively erupted tuya, Dalakvísl (~0.2 km3) is an entirely subglacial edifice that has both explosive and effusive deposits and Bláhnúkur is a small volume (Bull Vol. [3] Tuffen et al. (2007) Ann Glac, 45(1): 87-94

  13. An investigation of sediment toxicity in the Horse Lick Creek system (Upper Cumberland River drainage) (United States)

    US Fish and Wildlife Service, Department of the Interior — Microtox tests were used to assess the toxicity of water and sediment pore water samples collected from the Horse Lick Creek system in southeastern Kentucky. A...

  14. The Subglacial Access and Fast Ice Research Experiment (SAFIRE): 1. Programme of investigation on Store Glacier, West Greenland (United States)

    Christoffersen, Poul; Hubbard, Bryn; Bougamont, Marion; Doyle, Samuel; Young, Tun Jan; Hofstede, Coen; Nicholls, Keith; Todd, Joe; Box, Jason; Ryan, Johnny; Toberg, Nick; Walter, Jacob; Hubbard, Alun


    Marine-terminating outlet glaciers drain 90 percent of the Greenland Ice Sheet and are responsible for about half of the ice sheet's net annual mass loss, which currently raises global sea level by almost 1 mm per year. Understanding the processes that drive the fast flow of these glaciers is crucial because a growing body of evidence points to a strong, but spatially varied and often complex, response to oceanographic as well as atmospheric forcing. While the bed of glaciers elsewhere is known to strongly influence the flow of ice, no observations have ever been made at the bed of a marine-terminating glacier in Greenland. The flow of ice in numerical models of the Greenland Ice Sheet consequently rely on untested basal parameterisations, which form a likely and potentially significant source of error in the prediction of sea level rise over the coming decades and century. The Subglacial Access and Fast Ice Research Experiment (SAFIRE) is addressing this paucity of observational constraints by gaining access to the bed of Store Glacier, a marine-terminating outlet of the Greenland Ice Sheet which has a drainage basin of 35,000 square kilometres and terminates in Uummannaq Fjord. In 2014, the SAFIRE programme drilled four boreholes in a region where ice flows at a rate of 700 m per year and where a seismic survey revealed a bed consisting of soft sediment. (See joint abstract by Hofstede et al. for details.) The boreholes were 603-616 m deep and direct access to the bed was confirmed by a clear hydrological connectivity with a basal water system. (See joint abstract by Doyle et al. for details.) With sensors deployed englacially (temperature and tilt) and at the bed (water pressure, turbidity, electrical conductivity), the SAFIRE will inform the ratio of internal ice deformation and basal slip, vertical strain, ice temperature, and fluctuations in water pressure linked to supraglacial lake drainage as well as diurnal drainage into moulins. In 2015, we plan to

  15. Droplet coalescence: drainage, film rupture and neck growth in ultralow interfacial tension systems

    NARCIS (Netherlands)

    Aarts, D.G.A.L.; Lekkerkerker, H.N.W.|info:eu-repo/dai/nl/159054885


    We study the coalescence of a drop with its bulk phase in fluid–fluid demixing colloid–polymer mixtures. Such mixtures show behaviour analogous to molecular fluid–fluid systems, but the interfacial tension is between 105 to 107 times smaller than in the molecular case. Such an ultralow interfacial

  16. Info-Gap robustness pathway method for transitioning of urban drainage systems under deep uncertainties. (United States)

    Zischg, Jonatan; Goncalves, Mariana L R; Bacchin, Taneha Kuzniecow; Leonhardt, Günther; Viklander, Maria; van Timmeren, Arjan; Rauch, Wolfgang; Sitzenfrei, Robert


    In the urban water cycle, there are different ways of handling stormwater runoff. Traditional systems mainly rely on underground piped, sometimes named 'gray' infrastructure. New and so-called 'green/blue' ambitions aim for treating and conveying the runoff at the surface. Such concepts are mainly based on ground infiltration and temporal storage. In this work a methodology to create and compare different planning alternatives for stormwater handling on their pathways to a desired system state is presented. Investigations are made to assess the system performance and robustness when facing the deeply uncertain spatial and temporal developments in the future urban fabric, including impacts caused by climate change, urbanization and other disruptive events, like shifts in the network layout and interactions of 'gray' and 'green/blue' structures. With the Info-Gap robustness pathway method, three planning alternatives are evaluated to identify critical performance levels at different stages over time. This novel methodology is applied to a real case study problem where a city relocation process takes place during the upcoming decades. In this case study it is shown that hybrid systems including green infrastructures are more robust with respect to future uncertainties, compared to traditional network design.

  17. [Preventing fat embolism syndrome (FES) in implantation of cemented hip endoprosthesis shafts with a trans-prosthetic drainage system (TDS)]. (United States)

    Schmidt, J; Sulk, C; Weigand, C; La Rosée, K; Schneider, T


    In vitro studies with the transprosthetic drainage system (TDS) have revealed a reduction in intrafemoral pressure in cemented total hip prosthesis. The aim of the present study was to establish whether the incidence of fat embolic syndrome (FES) is also reduced. Ten patients underwent standardized cemented total hip replacement using TDS under standardized general anaesthesia. The usual peri-operative monitoring measures were extended to include cardiopulmonary monitoring (pulmonary artery catheter, intra-arterial blood pressure) and two-dimensional transoesophageal echocardiography. Previous studies had reported an increased risk for fat embolic syndrome with conventional, and even with vacuum cementing techniques. Our recorded cardiopulmonary data and the data provided by two-dimensional transoesophageal echocardiography show a significant reduction in pulmonary embolism with TDS. This technique can be recommended in particular for high-risk patients (osteoporosis, elderly patients) and the implantation of long femoral stems. On the basis of the clinical data, a new femoral stem allowing the use of the TDS technique is being developed.

  18. Natural wetlands are efficient at providing long-term metal remediation of freshwater systems polluted by acid mine drainage. (United States)

    Dean, Andrew P; Lynch, Sarah; Rowland, Paul; Toft, Benjamin D; Pittman, Jon K; White, Keith N


    This study describes the first long-term (14-year) evaluation of the efficacy of an established (>100 years) natural wetland to remediate highly acidic mine drainage (AMD). Although natural wetlands are highly valued for their biodiversity, this study demonstrates that they also provide important ecosystem service functions through their ability to consistently and reliably improve water quality by mitigating AMD. The Afon Goch river flows from Parys Mountain copper mine via a natural wetland, and was the major source of Zn and Cu contamination to the Irish Sea. Prior to 2003 the wetland received severe acidic metal contamination and retained a large proportion of the contamination (55, 64, and 37% in dissolved Fe, Zn, and Cu) leading to a greatly reduced metal flow to the Irish Sea. Reduced wetland loadings midway through the sampling period led to a reduction of metals by 83-94% and a pH increase from 2.7 to 5.5, resulting in long-term improvements in the downstream benthic invertebrate community. High root metal accumulation by the dominant wetland plant species and the association of acidophilic bacteria in the wetland rhizosphere indicate that multiple interacting processes provide an efficient and self-sustaining system to remediate AMD.

  19. Environmental assessment and management of metal-rich wastes generated in acid mine drainage passive remediation systems. (United States)

    Macías, Francisco; Caraballo, Manuel A; Nieto, José Miguel


    As acid mine drainage (AMD) remediation is increasingly faced by governments and mining industries worldwide, the generation of metal-rich solid residues from the treatments plants is concomitantly raising. A proper environmental management of these metal-rich wastes requires a detailed characterization of the metal mobility as well as an assessment of this new residues stability. The European standard leaching test EN 12457-2, the US EPA TCLP test and the BCR sequential extraction procedure were selected to address the environmental assessment of dispersed alkaline substrate (DAS) residues generated in AMD passive treatment systems. Significant discrepancies were observed in the hazardousness classification of the residues according to the TCLP or EN 12457-2 test. Furthermore, the absence of some important metals (like Fe or Al) in the regulatory limits employed in both leaching tests severely restricts their applicability for metal-rich wastes. The results obtained in the BCR sequential extraction suggest an important influence of the landfill environmental conditions on the metals released from the wastes. To ensure a complete stability of the pollutants in the studied DAS-wastes the contact with water or any other leaching solutions must be avoided and a dry environment needs to be provided in the landfill disposal selected. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Pathways and Transit Time of Meltwater in the Englacial Drainage System of Rabots Glacier, Kebnekaise, Sweden


    Coch, Caroline


    Following the crash of a Norwegian Hercules aircraft on Rabots glaciär in the Kebnekaise mountain range in 2012, a field campaign was initiated in order to assess the fate of the hydrocarbon pollution in the system. It is hypothesized that soluble components of the aircraft fuel will be transported within the glacial meltwater. This thesis focuses on constraining the likely transit time and dispersion of the meltwater as a proxy for potential pollution pathways. Therefore, the hydrologic con...

  1. Flow Control and Design Assessment for Drainage System at McMurdo Station, Antarctica (United States)


    soils that are not bound to the surface by root systems found more commonly in humid regions (McKnight 1990). Furthermore, arid and semi - arid lands...Our study assumes the reference Shields stress to have a value of 0.0876. In a review of bed-load transport formulations in desert arid climates ...Coppus, R., and A. C. Imeson. 2002. Extreme events controlling erosion and sediment transport in a semi - arid Sub-Andean Valley. Earth Surface

  2. Stormwater Drainage Wells (United States)

    Provides information for identifying stormwater drainage wells, learn how to comply with regulations for storm water drainage wells, and how to reduce the threat to ground water from stormwater injection wells.

  3. Observation of field- scale preferential flow in soil landscapes with kettle holes as internal drainage system (United States)

    Gerke, Horst H.


    Complementary to pedon-scale phenomena (e.g., macropore flow in structured soil), preferential flow may be also defined at larger scales mainly along impeding structures that allow for the development of transient ‘local' non-equilibrium in water potentials depending on characteristic boundary conditions. The phenomenon is then related to a ‘global' system (i.e., field, hillslope, or catchment). Larger scale preferential flow processes have recently been hypothesized although full conceptual understanding for model development remains challenging. The objective of this contribution is to discuss field observations of area-scale preferential water flow for improving the conceptual model. Examples are from a typical post-glacial landscape with kettle holes (i.e., site Grünow, north East Germany) as internal catchment systems where surface runoff and lateral subsurface flow occur. Where soils are developed from the till, and predominately used for agriculture, water moves along the surface as runoff or within highly conductive soil regions before it enters the central depression. From there it may either evaporate or eventually lead to depression-focussed recharge. Observations show lateral flow ‘bypassing' relatively dry subsoil in most of the catchment and re-wetting the subsoil near the depression by lateral infiltration from the pond indicated by reversal of hydraulic gradients. Results suggest that surface runoff is dominating the hydrological regime during the winter when the soil is frozen and in the summer during storm events. The lateral exchange fluxes between pond and surrounding soil suggest that additional geomorphologic and pedologic structures affect the hydrological function of the system. Ponds can trap large volumes of surface runoff and control seepage function. The field-scale lateral preferential flow can strongly control percolation and discharge and may be a possible route for ground water contamination.

  4. Transient drainage summary report

    Energy Technology Data Exchange (ETDEWEB)



    This report summarizes the history of transient drainage issues on the Uranium Mill Tailings Remedial Action (UMTRA) Project. It defines and describes the UMTRA Project disposal cell transient drainage process and chronicles UMTRA Project treatment of the transient drainage phenomenon. Section 4.0 includes a conceptual cross section of each UMTRA Project disposal site and summarizes design and construction information, the ground water protection strategy, and the potential for transient drainage.

  5. A lander mission to probe subglacial water on Saturn's moon Enceladus for life (United States)

    Konstantinidis, Konstantinos; Flores Martinez, Claudio L.; Dachwald, Bernd; Ohndorf, Andreas; Dykta, Paul; Bowitz, Pascal; Rudolph, Martin; Digel, Ilya; Kowalski, Julia; Voigt, Konstantin; Förstner, Roger


    The plumes discovered by the Cassini mission emanating from the south pole of Saturn's moon Enceladus and the unique chemistry found in them have fueled speculations that Enceladus may harbor life. The presumed aquiferous fractures from which the plumes emanate would make a prime target in the search for extraterrestrial life and would be more easily accessible than the moon's subglacial ocean. A lander mission that is equipped with a subsurface maneuverable ice melting probe will be most suitable to assess the existence of life on Enceladus. A lander would have to land at a safe distance away from a plume source and melt its way to the inner wall of the fracture to analyze the plume subsurface liquids before potential biosignatures are degraded or destroyed by exposure to the vacuum of space. A possible approach for the in situ detection of biosignatures in such samples can be based on the hypothesis of universal evolutionary convergence, meaning that the independent and repeated emergence of life and certain adaptive traits is wide-spread throughout the cosmos. We thus present a hypothetical evolutionary trajectory leading towards the emergence of methanogenic chemoautotrophic microorganisms as the baseline for putative biological complexity on Enceladus. To detect their presence, several instruments are proposed that may be taken aboard a future subglacial melting probe. The "Enceladus Explorer" (EnEx) project funded by the German Space Administration (DLR), aims to develop a terrestrial navigation system for a subglacial research probe and eventually test it under realistic conditions in Antarctica using the EnEx-IceMole, a novel maneuverable subsurface ice melting probe for clean sampling and in situ analysis of ice and subglacial liquids. As part of the EnEx project, an initial concept study is foreseen for a lander mission to Enceladus to deploy the IceMole near one of the active water plumes on the moon's South-Polar Terrain, where it will search for

  6. Probabilistic runoff volume forecasting in risk-based optimization for RTC of urban drainage systems

    DEFF Research Database (Denmark)

    Löwe, Roland; Vezzaro, Luca; Mikkelsen, Peter Steen


    This article demonstrates the incorporation of stochastic grey-box models for urban runoff forecasting into a full-scale, system-wide control setup where setpoints are dynamically optimized considering forecast uncertainty and sensitivity of overflow locations in order to reduce combined sewer...... overflow risk. The stochastic control framework and the performance of the runoff forecasting models are tested in a case study in Copenhagen (76 km2 with 6 sub-catchments and 7 control points) using 2-h radar rainfall forecasts and inlet flows to control points computed from a variety of noisy....../oscillating in-sewer measurements. Radar rainfall forecasts as model inputs yield considerably lower runoff forecast skills than “perfect” gauge-based rainfall observations (ex-post hindcasting). Nevertheless, the stochastic grey-box models clearly outperform benchmark forecast models based on exponential...

  7. Sediments from stormwater drainage system as sorbents of organic and inorganic pollutants (United States)

    Sałata, Aleksandra; Dąbek, Lidia


    The study presents the results of tests aimed at determining variations in concentrations of polycyclic aromatic hydrocarbons (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a, h]anthracene, benzo[g, h, i]perylene and indeno[1, 2, 3-c, d]pyrene) and heavy metals (copper, cadmium, chromium, nickel, lead and zinc) in the sediments from the stormwater sewer system. Results of this study were then compared to Polish regulations and established ecological screening values to determine their potential risk to environment. The results suggest that stormwater sediments are moderately contaminated with PAHs and heavy metals according to domestic regulations and highly contaminated according to ecological benchmarks.

  8. Profiling microbial communities in manganese remediation systems treating coal mine drainage. (United States)

    Chaput, Dominique L; Hansel, Colleen M; Burgos, William D; Santelli, Cara M


    Water discharging from abandoned coal mines can contain extremely high manganese levels. Removing this metal is an ongoing challenge. Passive Mn(II) removal beds (MRBs) contain microorganisms that oxidize soluble Mn(II) to insoluble Mn(III/IV) minerals, but system performance is unpredictable. Using amplicon pyrosequencing, we profiled the bacterial, fungal, algal, and archaeal communities in four MRBs, performing at different levels, in Pennsylvania to determine whether they differed among MRBs and from surrounding soil and to establish the relative abundance of known Mn(II) oxidizers. Archaea were not detected; PCRs with archaeal primers returned only nontarget bacterial sequences. Fungal taxonomic profiles differed starkly between sites that remove the majority of influent Mn and those that do not, with the former being dominated by Ascomycota (mostly Dothideomycetes) and the latter by Basidiomycota (almost entirely Agaricomycetes). Taxonomic profiles for the other groups did not differ significantly between MRBs, but operational taxonomic unit-based analyses showed significant clustering by MRB with all three groups (P < 0.05). Soil samples clustered separately from MRBs in all groups except fungi, whose soil samples clustered loosely with their respective MRB. Known Mn(II) oxidizers accounted for a minor proportion of bacterial sequences (up to 0.20%) but a greater proportion of fungal sequences (up to 14.78%). MRB communities are more diverse than previously thought, and more organisms may be capable of Mn(II) oxidation than are currently known. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  9. Treatment of heavy metals by iron oxide coated and natural gravel media in Sustainable urban Drainage Systems. (United States)

    Norris, M J; Pulford, I D; Haynes, H; Dorea, C C; Phoenix, V R


    Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to facilitate improved SuDS design. Since heavy metals are a large fraction of pollution in road runoff, this study aimed to enhance heavy metal removal of filter drain gravel with an iron oxide mineral amendment to increase surface area for heavy metal scavenging. Experiments showed that amendment-coated and uncoated (control) gravel removed similar quantities of heavy metals. Moreover, when normalized to surface area, iron oxide coated gravels (IOCGs) showed poorer metal removal capacities than uncoated gravel. Inspection of the uncoated microgabbro gravel indicated that clay particulates on the surface (a natural product of weathering of this material) augmented heavy metal removal, generating metal sequestration capacities that were competitive compared with IOCGs. Furthermore, when the weathered surface was scrubbed and removed, metal removal capacities were reduced by 20%. When compared with other lithologies, adsorption of heavy metals by microgabbro was 10-70% higher, indicating that both the lithology of the gravel, and the presence of a weathered surface, considerably influence its ability to immobilize heavy metals. These results contradict previous assumptions which suggest that gravel lithology is not a significant factor in SuDS design. Based upon these results, weathered microgabbro is suggested to be an ideal lithology for use in SuDS.

  10. Geological controls on bedrock topography and ice sheet dynamics in the Wilkes Subglacial Basin sector of East Antarctica (United States)

    Ferraccioli, Fausto; Armadillo, Egidio; Young, Duncan; Blankenship, Donald; Jordan, Tom; Siegert, Martin


    The Wilkes Subglacial Basin extends for 1,400 km into the interior of East Antarctica and hosts several major glaciers that drain a large sector of the East Antarctic Ice Sheet. The deep northern Wilkes Subglacial Basin underlies the catchments of the Matusevich, Cook, Ninnis and Mertz Glaciers, which are largely marine-based and hence potentially particularly sensitive to past and also predicted future ocean and climate warming. Sediment provenance studies suggest that the glaciers flowing in this region may have retreated significantly compared to their modern configuration, as recently as the warm mid-Pliocene interval, potentially contributing several m to global sea level rise (Cook et al.,Nature Geosci., 2013). Here we combine airborne radar, aeromagnetic and airborne gravity observations collected during the international WISE-ISODYN and ICECAP aerogeophysical campaigns with vintage datasets to help unveil subglacial geology and deeper crustal architecture and to assess its influence on bedrock topography and ice sheet dynamics in the northern Wilkes Subglacial Basin. Aeromagnetic images reveal that the Matusevich Glacier is underlain by a ca 480 Ma thrust fault system (the Exiles Thrust), which has also been inferred to have been reactivated in response to intraplate Cenozoic strike-slip faulting. Further to the west, the linear Eastern Basins are controlled by the Prince Albert Fault System. The fault system continues to the south, where it provides structural controls for both the Priestley and Reeves Glaciers. The inland Central Basins continue in the coastal area underlying the fast flowing Cook ice streams, implying that potential ocean-induced changes could propagate further into the interior of the ice sheet. We propose based on an analogy with the Rennick Graben that these deep subglacial basins are controlled by the underlying horst and graben crustal architecture. Given the interpreted subglacial distribution of Beacon sediments and Ferrar

  11. Action research: an appropriate research methodology to develop on-farm drainage systems with farmers with reference to the NRAP Project, Pakistan


    Schrevel, A.; Bhutta, M.N.


    In the period up till 2000 the Netherlands Research Assistance Project (NRAP) ran an Action Research programme to develop a drainage system together with farmers in an area suffering from salinity and waterlogging. Executing parties of NRAP were the International Waterlogging and Salinity Research Institute (IWASRI), Pakistan¿s main research institute in salinity and waterlogging research, and International Institute for Land Reclamation and Improvement (Alterra-ILRI), based in the The Nether...

  12. Systems for pipeline drainage and drying: pigs pass with flying colors. Robust polyurethane elastomer materials for made-to-measure, abrasion resistant pipeline pigs

    Energy Technology Data Exchange (ETDEWEB)

    Els, Detlev [Weatherford Kopp GmbH, Lingen (Germany); Passmann, Dirk [Bayer MaterialScience AG, Leverkusen (Germany)


    The pipeline pig system developed for drainage of a long offshore pipeline with two different diameters was a world first that placed extreme demands on the pig design and the materials used. The polyurethane elastomer Baytec registered Q. used for the pig's disks, passed this ''acid test'' with flying colors thanks to its superior properties - accurately dimensioned cast disks, variable hardness, exceptional abrasion resistance, high elasticity, tear strength and resistance to chemicals. (orig.)

  13. The strategies of local farmers' water management and the eco-hydrological effects of irrigation-drainage engineering systems in world heritage of Honghe Hani Rice Terraces (United States)

    Gao, Xuan


    Terraces are built in mountainous regions to provide larger area for cultivation,in which the hydrological and geomorphological processes are impacted by local farmers' water management strategies and are modified by manmade irrigation-drainage engineering systems.The Honghe Hani Rice Terraces is a 1300a history of traditional agricultural landscape that was inscribed in the 2013 World Heritage List.The local farmers had developed systematic water management strategies and built perfect irrigation-drainage engineering systems to adapt the local rainfall pattern and rice farming activities.Through field investigation,interviews,combined with Geographic Information Systems,Remote Sensing images and Global Positioning Systems technology,the water management strategies as well as the irrigation-drainage systems and their impacts on eco-hydrological process were studied,the results indicate:Firstly,the local people created and maintained an unique woodcarving allocating management system of irrigating water over hundreds years,which aids distributing water and natural nutrition to each terrace field evenly,and regularly according to cultivation schedule.Secondly,the management of local people play an essential role in effective irrigation-drainage engineering system.A ditch leader takes charge of managing the ditch of their village,keeping ample amount of irrigation water,repairing broken parts of ditches,dealing with unfair water using issues,and so on.Meanwhile,some traditional leaders of minority also take part in.Thus, this traditional way of irrigation-drainage engineering has bringed Hani people around 1300 years of rice harvest for its eco-hydrological effects.Lastly we discuss the future of Honghe Hani Rice Terraces,the traditional cultivation pattern has been influenced by the rapid development of modern civilization,in which some related changes such as the new equipment of county roads and plastic channels and the water overusing by tourism are not totally

  14. Exploring Explanations of Subglacial Bedform Sizes Using Statistical Models.

    Directory of Open Access Journals (Sweden)

    John K Hillier

    Full Text Available Sediments beneath modern ice sheets exert a key control on their flow, but are largely inaccessible except through geophysics or boreholes. In contrast, palaeo-ice sheet beds are accessible, and typically characterised by numerous bedforms. However, the interaction between bedforms and ice flow is poorly constrained and it is not clear how bedform sizes might reflect ice flow conditions. To better understand this link we present a first exploration of a variety of statistical models to explain the size distribution of some common subglacial bedforms (i.e., drumlins, ribbed moraine, MSGL. By considering a range of models, constructed to reflect key aspects of the physical processes, it is possible to infer that the size distributions are most effectively explained when the dynamics of ice-water-sediment interaction associated with bedform growth is fundamentally random. A 'stochastic instability' (SI model, which integrates random bedform growth and shrinking through time with exponential growth, is preferred and is consistent with other observations of palaeo-bedforms and geophysical surveys of active ice sheets. Furthermore, we give a proof-of-concept demonstration that our statistical approach can bridge the gap between geomorphological observations and physical models, directly linking measurable size-frequency parameters to properties of ice sheet flow (e.g., ice velocity. Moreover, statistically developing existing models as proposed allows quantitative predictions to be made about sizes, making the models testable; a first illustration of this is given for a hypothesised repeat geophysical survey of bedforms under active ice. Thus, we further demonstrate the potential of size-frequency distributions of subglacial bedforms to assist the elucidation of subglacial processes and better constrain ice sheet models.

  15. Sustainable drainage system

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn


    Full Text Available Conventional human settlement formation creates hard surfaces which impede the natural absorption of rainfall into the ground. Water collected from these hard surfaces has to be conveyed to some end destination where it is discharged. This has a...

  16. Sustainable Urban Drainage Systems

    DEFF Research Database (Denmark)

    Hoffmann, Birgitte; Laustsen, Anne; Jensen, Inge H.

    he white paper presents the various possibilities of using rainwater as a resource as opposed to considering it as something that simply needs to be hidden in sewers. The aim of using rainwater as a resource is partly to reduce the risk of flooding by optimising the rainwater management and partl...

  17. Distribution and emission of oxamyl in a rockwool cultivation system with open drainage of the nutrient solution

    NARCIS (Netherlands)

    Runia, W.T.; Dekker, A.; Houx, N.W.H.


    On a 1.8 ha eggplant nursery with open drainage of the excess of nutrient solution the distribution of oxamyl was measured after it had been added to the nutrient solution. When it was applied via injection at a tap of a section, the distribution was more uniform than when applied via the central

  18. Illinois drainage water management demonstration project (United States)

    Pitts, D.J.; Cooke, R.; Terrio, P.J.; ,


    Due to naturally high water tables and flat topography, there are approximately 4 million ha (10 million ac) of farmland artificially drained with subsurface (tile) systems in Illinois. Subsurface drainage is practiced to insure trafficable field conditions for farm equipment and to reduce crop stress from excess water within the root zone. Although drainage is essential for economic crop production, there have been some significant environmental costs. Tile drainage systems tend to intercept nutrient (nitrate) rich soil-water and shunt it to surface water. Data from numerous monitoring studies have shown that a significant amount of the total nitrate load in Illinois is being delivered to surface water from tile drainage systems. In Illinois, these drainage systems are typically installed without control mechanisms and allow the soil to drain whenever the water table is above the elevation of the tile outlet. An assessment of water quality in the tile drained areas of Illinois showed that approximately 50 percent of the nitrate load was being delivered through the tile systems during the fallow period when there was no production need for drainage to occur. In 1998, a demonstration project to introduce drainage water management to producers in Illinois was initiated by NRCS4 An initial aspect of the project was to identify producers that were willing to manage their drainage system to create a raised water table during the fallow (November-March) period. Financial assistance from two federal programs was used to assist producers in retrofitting the existing drainage systems with control structures. Growers were also provided guidance on the management of the structures for both water quality and production benefits. Some of the retrofitted systems were monitored to determine the effect of the practice on water quality. This paper provides background on the water quality impacts of tile drainage in Illinois, the status of the demonstration project, preliminary

  19. Evaluation of a digital drainage system (Thopaz) in over 250 cases at a single site: A retrospective case-control study. (United States)

    Arai, Hiromasa; Tajiri, Michihiko; Kameda, Yohei; Shiino, Kimihisa; Ando, Kohei; Okudela, Koji; Masuda, Munetaka


    The aim of this study was to evaluate the efficacy of the Thopaz system, a new drainage system in management of general thoracic surgery, based on a review of our clinical practice and a comparison of the utility of the Thopaz device compared with a standard drainage system. A review of 540 thoracic surgeries at our hospital was performed. These cases were divided into 275 treated with the Thopaz system from April 2014 to March 2015 and 265 treated with a standard system from April 2013 to March 2014. The characteristics of patients and outcomes after surgery were compared in these 2 groups. The characteristics of the patients were similar in the 2 groups. Outcomes after surgery, including types of operation, period of chest tube placement, chest tube reinsertion rate and clamping test rate also did not differ significantly between the groups. The non-inferiority of the Thopaz system compared to a standard system was verified statistically. With advantages of providing objective data as a small portable system, in addition to the quietness of the unit and the ease of setup and operation, Thopaz system is likely to become mainstream in postoperative management in general thoracic surgery. © 2017 John Wiley & Sons Ltd.

  20. The Wilkes subglacial basin eastern margin electrical conductivity anomaly (United States)

    Rizzello, Daniele; Armadillo, Egidio; Ferraccioli, Fausto; Caneva, Giorgio


    We have analyzed the deep conductivity structure at the transition between the Transantarctic Mountains (TAM) and the eastern margin of the WSB in NVL, by means of the GDS (Geomagnetic Deep Sounding) technique, in order to constrain the geodynamical interpretation of this antarctic sector. The TAM form the uplifted flank of the Mesozoic and Cenozoic West Antarctic Rift System. Structure of the TAM rift flank has been partially investigated with different geophysical approaches.The Wilkes Subglacial Basin is a broad depression over 400 km wide at the George V Coast and 1200 km long. Geology, lithospheric structure and tectonics of the Basin are only partially known because the Basin is buried beneath the East Antarctic Ice Sheet and is located in a remote region which makes geophysical exploration logistically challenging. Different authors have proposed contrasting hypothesis regarding the origin of the WSB: it could represent a region of rifted continental crust, or it may have a flexural origin or might represent an "extended terrane". Recently aerogeophysical investigations have demonstrated a strong structural control on the margin. Magnetovariational studies carried out at high geomagnetic latitudes are often hampered by source effects, mainly due to the closeness to the Polar Electrojet currents systems (PEJ). Its presence, in fact, makes the uniform magnetic field assumption, on which the magnetovariational methods are based on, often invalid, which outcome is a bias in the GDS transfer functions and to compromise the reliability of the inverted models. Data from the aforementioned campaigns have been then processed under the ISEE project (Ice Sheet Electromagnetic Experiment), aimed at evaluate and mitigate the bias effect of the PEJ on geomagnetic an magnetotelluric transfer functions at high geomagnetic latitudes, by means of suitable processing algorithms, developed upon a statistical analysis study on PEJ effects (Rizzello et al. 2013). Recent results

  1. The 'Amstel Canal' in Amsterdam Canal construction as part of the medieval reclamation and drainage system of the Western Netherlands wilderness (United States)

    Abrahamse, Jaap-Evert; Kosian, Menne; Weerts, Henk


    Usually, Amsterdam is presented as a river city, with the river Amstel as the trade route towards its hinterland, the IJ sea-branch as the portal to the world and its Dam as a focal point of transshipment and trade. Geomorphological, sedimentological, historical and historical-geographical evidence however, points towards the straight part of the Amstel, now located in Amsterdam, as a drainage canal that was dug in the aftermath of the 'Great Reclamation' of the 11th and 12th centuries. During this period, large parts of the wilderness in Utrecht and Holland were cultivated and put to agricultural use. Prior to the 'Great Reclamations', large oligotrophic (Sphagnum) peat bogs drained by small rivers were characteristic of the entire region. All along the straight Amstel canal, Sphagnum peat is found, which is indicative of the area's former peat bog conditions. The 'Amstel Canal' connected two natural meandering watercourses, one at the north and one at the south of the canal. The soil along both watercourses exists of eutrophic peat, which is indicative of repeated natural flooding. This is a strong indication of the anthropogenous origin of the straight part of the Amstel. The reason for digging the Amstel canal was not to create better trade links; it was a local component of a solution for major regional drainage problems in the provinces of Utrecht and Holland. These problems arose from the silting up of the Rhine rivermouth around 1100AD. Because of this, the precipitation surplus of the entire region could not be drained to the North Sea by this route anymore. This led to increased flooding and subsequently to conflicts between the rulers of Holland and Utrecht. In 1165AD, these conflicts reached a point where the Holy Roman Emperor intervened. The ruling of Barbarossa eventually led to a compromise: Utrecht and Holland redirected the entire drainage system of the region from the North Sea to the Zuiderzee in a concerted effort. This operation consisted of

  2. Subglacial processes revealed by the internal structure of drumlins, Stargard drumlin field, NW Poland (United States)

    Hermanowski, Piotr; Piotrowski, Jan A.; Szuman-Kalita, Izabela


    Numerous studies have provided insight into processes operating under contemporary and palaeo-ice sheets. Many of these studies concerned drumlins, landforms whose formation is essential to the understanding of subglacial soft-bedded systems. Despite the interdisciplinary efforts involving sophisticated analytical and interpretative tools the "drumlin problem" remains elusive and continues to generate much controversy. In this study the geological composition of two drumlins from the Stargard drumlin field (NW Poland) in the terminal area of a major last-glacial palaeo-ice stream was examined in three excavated trenches at macro- and microscales. In each trench, sediment description and fabric analyses were conducted, and samples collected for micromorphological, AMS (anisotropy of magnetic susceptibility) and grain size measurements. Both investigated drumlins are mainly composed of macroscopically homogeneous till with minor, max. 5 cm thick sand stringers and sparse silty inclusions. Distinct features are (1) a highly deformed, up to 18-cm thick till layer with clay- and pebble-sized clasts at the top, and (2) a continuous thin intra-till clay layer. Till macro-fabric measurements reveal a very high clustering strength and low isotropy index. AMS eigenvectors V1 vary significantly, but the dominant direction is consistent with the macrofabric measurements. Most of the observed microstructures indicate ductile deformation of the till. The overall observations suggest a shallow subglacial deformation not affecting the entire till thickness at any time intervening with ice/bed separation facilitating enhanced basal sliding. The intra-till clay layer of low hydraulic conductivity contributed to elevated pore-water pressure in the sediment causing its fluidization and deformation. Intervening thin-skinned sediment deformation and basal de-coupling resulted in fast ice flow that, coupled with material release from the ice sole and its accretion at the ice

  3. A Unified Constitutive Model for Subglacial Till, Part I: The Disturbed State Concept (United States)

    Jenson, J. W.; Desai, C. S.; Clark, P. U.; Contractor, D. N.; Sane, S. M.; Carlson, A. E.


    Classical plasticity models such as Mohr-Coulomb may not adequately represent the full range of possible motion and failure in tills underlying ice sheets. Such models assume that deformations are initially elastic, and that when a peak or failure stress level is reached the system experiences sudden failure, after which the stress remains constant and the deformations can tend to infinite magnitudes. However, theory suggests that the actual behavior of deforming materials, including granular materials such as glacial till, can involve plastic or irreversible strains almost from the beginning, in which localized zones of microcracking and "failure" can be distributed over the material element. As the loading increases, and with associated plastic and creep deformations, the distributed failure zones coalesce. When the extent of such coalesced zones reaches critical values of stresses and strains, the critical condition (failure) can occur in the till, which would cause associated movements of the ice sheet. Failure or collapse then may occur at much larger strain levels. Classical models (e.g., Mohr-Coulomb) may therefore not be able to fully and realistically characterize deformation behavior and the gradual developments of localized failures tending to the global failure and movements. We present and propose the application of the Disturbed State Concept (DSC), a unified model that incorporates the actual pre- and post-failure behavior, for characterizing the behavior of subglacial tills. In this presentation (Part I), we describe the DSC and propose its application to subglacial till. Part II (Desai et al.) describes our application of the DSC with laboratory testing, model calibration, and validations to evaluate the mechanical properties of two regionally significant Pleistocene tills.

  4. Development and Antarctic Testing of a Maneuverable Probe for Clean In-Situ Analysis and Sampling of Subsurface Ice and Subglacial Aquatic Ecosystems (United States)

    Francke, G.; Dachwald, B.; Kowalski, J.; Digel, I.; Tulaczyk, S. M.; Mikucki, J.; Feldmann, M.; Espe, C.; Schöngarth, S.; Hiecker, S.; Blandfort, D.; Schüller, K.; Plescher, E.


    There is significant interest in sampling subglacial environments for geochemical and microbiological studies, but those environments are difficult to access. Such environments exist not only on Earth but are also expected beneath the icy crusts of some outer solar system bodies, like the Jovian moon Europa and the Saturnian moon Enceladus. Existing ice drilling technologies make it cumbersome to maintain microbiologically clean access for sample acquisition and environmental stewardship of potentially fragile subglacial aquatic ecosystems. The "IceMole" is a maneuverable subsurface ice probe for clean in-situ analysis and sampling of glacial ice and subglacial materials. The design is based on combining melting and mechanical propulsion, using an ice screw at the tip of the melting head to maintain firm contact between the melting head and the ice. It can change melting direction by differential heating of the melting head and optional side wall heaters. The first two prototypes were successfully tested between 2010 and 2012 on glaciers in Switzerland and Iceland, where they demonstrated downward, horizontal and upward melting, as well as curve driving and dirt layer penetration. Hence, the IceMole allows maneuvers which may be necessary for obstacle avoidance or target selection. Maneuverability, however, necessitates a sophisticated on-board navigation system capable of autonomous operations. Therefore, between 2012 and 2014, a more advanced probe was developed as part of the "Enceladus Explorer" (EnEx) project. The EnEx-IceMole offers systems for relative positioning based on in-ice attitude determination, acoustic positioning, ultrasonic obstacle and target detection, which is all integrated through a high-level sensor fusion. In December 2014, it was used for clean access into a unique subglacial aquatic environment at Blood Falls, Antarctica, where a subglacial brine sample was successfully obtained after about 17 meters of oblique melting. Particular

  5. [Ascites drainage at home

    NARCIS (Netherlands)

    Lutjeboer, J.; Erkel, A.R. van; Hoeven, J.J.M. van der; Meer, R.W. van der


    Ascites can lead to many symptoms, and often occurs in patients with an end-stage malignancy such as ovarian, pancreatic, colonic, or gastric cancer. Intermittent ascites drainage is applied in these patients as a palliative measure. As frequent drainage is necessary, a subcutaneously tunnelled


    Directory of Open Access Journals (Sweden)

    S. A. Bulat


    Full Text Available The objective was to estimate the genuine microbial content of ice samples from refrozen water (accretion ice from the subglacialLakeVostok(Antarctica buried beneath the 4-km thick East Antarctic ice sheet as well as surface snow nearby Vostok station. The lake ice samples were extracted by heavy deep ice drilling from3764 mbelow the surface reaching the depth3769.3 mby February 2011 (lake entering. High pressure, an ultra low carbon and chemical content, isolation, complete darkness and the probable excess of oxygen in water for millions of years characterize this extreme environment. A decontamination protocol was first applied to samples selected for the absence of cracks to remove the outer part contaminated by handling and drilling fluid. Preliminary indications showed the accretion ice samples to be almost gas free with the very low impurity content. Flow cytometry showed the very low unevenly distributed biomass in both accretion (0–19 cells per ml and glacier (0–24 cells per ml ice and surface snow (0–0.02 cells per ml as well while repeated microscopic observations were unsuccessful meaning that the whole Central East Antarctic ice sheet seems to be microbial cell-free.We used strategies of Ancient DNA research that include establishing contaminant databases and criteria to validate the amplification results. To date, positive results that passed the artifacts and contaminant databases have been obtained for a few bacterial phylotypes only in accretion ice samples featured by some bedrock sediments. Amongst them are the chemolithoautotrophic thermophile Hydrogenophilus thermoluteolus of beta-Proteobacteria, the actinobacterium rather related (95% to Ilumatobacter luminis and one unclassified phylotype distantly related (92% to soil-inhabiting uncultured bacteria. Combined with geochemical and geophysical considerations, our results suggest the presence of a deep biosphere, possibly thriving within some active faults of the bedrock

  7. Impact of an aseptic procedure for breaking the integrity of the urinary drainage system on the development of catheter-associated urinary tract infections in the intensive care unit. (United States)

    Powers, Jan


    Catheter associated urinary tract infections (CAUTI) are a common complication in the hospital, especially in intensive care units (ICU). These infections are directly linked to the use of an indwelling urinary catheter. One commonly identified factor related to the development of CAUTI has been thought to be violating the integrity of the closed drainage system. However, a paucity of research exists to support or refute this practice. The primary purpose of this observational study was to assess if there is a relationship between CAUTI incidence and breaking the closed drainage system using an aseptic procedure. A process improvement effort was developed to ensure an aseptic technique was utilised when there was a need to break the integrity of the urinary drainage system. Because this was a new practice and not supported by the Centres for Disease Control (CDC) recommendations, this change in practice was evaluated as an observational study. In an eight month period there were 53 documented breaks in the urinary drainage system. There were 28 total cases of CAUTI overall during this same time period. Only four patients with a system break developed a CAUTI (7.5%). In almost 93% of the patients where aseptic technique was used for breaks in the drainage system, there was no occurrence of CAUTI. A follow-up evaluation was performed after a year of this practice in three adult ICUs. During this three month evaluation period, there were 47 documented cases of breaking this system using aseptic technique. Of the patients who had a documented break in their drainage system, none developed subsequent CAUTIs. One commonly identified factor related to the development of CAUTI has been thought to be violating the integrity of the closed drainage system. However, a paucity of research exists to support or refute this practice. This observational study found that utilising an aseptic technique to break the integrity system did not result in an associated increase in CAUTI

  8. Distinguishing high and low flow domains in urban drainage systems 2 days ahead using numerical weather prediction ensembles (United States)

    Courdent, Vianney; Grum, Morten; Mikkelsen, Peter Steen


    members. While the first and second approaches have the disadvantage of not covering the full range of the ROC diagram and being computationally heavy, respectively, the third approach leads to both a broad coverage of the ROC diagram range at a relatively low computational cost. A broad coverage of the ROC diagram offers a larger selection of prediction skill to choose from to best match to the prediction purpose. The study distinguishes itself from earlier research in being the first application to urban hydrology, with fast runoff and small catchments that are highly sensitive to local extremes. Furthermore, no earlier reference has been found on the highly efficient third approach using only neighbouring cells with the highest threat to expand the range of the ROC diagram. This study provides an efficient and robust approach to using ensemble rainfall forecasts affected by bias and misplacement errors for predicting flow threshold exceedance in urban drainage systems.

  9. SANitation CHoice Involving Stakeholders : a participatory multi-criteria method for drainage and sanitation system selection in developing cities applied in Ho Chi Minh City, Vietnam

    NARCIS (Netherlands)

    Buuren, van J.C.L.


    Keywords: sanitation; drainage; planning; multi-criteria decision analysis; stakeholder dialogues, developing countries The poor living in slums and other unplanned urban areas in developing countries have no access to adequate drainage and sanitation provisions with grave consequences to their

  10. Modeling spatially and temporally varied hydraulic behavior of a folded karst system with dominant conduit drainage at catchment scale, Hochifen-Gottesacker, Alps (United States)

    Chen, Zhao; Goldscheider, Nico


    Karst aquifers are important for freshwater supply, but difficult to manage, due to highly variable water levels and spring discharge rates. Conduits are crucial for groundwater flow in karst aquifers, but their location is often unknown, thus limiting the applicability and validity of numerical models. We have applied a conduit model (SWMM) to simulate highly variable flow in a folded alpine karst aquifer system, where the underground drainage pattern is comparatively well-known from previous tracer studies. The conduit model was coupled with a reservoir model representing recharge, storage and transfer of water in the epikarst and unsaturated zone. The global optimization approach (GA) was applied to achieve an efficient model calibration. It was possible to simultaneously simulate the highly variable discharge characteristics of an estavelle, and overflow spring and a permanent spring draining the conduit system. The model allowed for the collection of spatially differentiated information on recharge, rapid flow and slow flow in four individual sub-catchments. The formation of backwater upgradient from conduit restrictions turned out to be a key process in activating overflow springs. The proposed modeling approach appears to be transferrable to other karst systems with predominant conduit drainage, but requires previous knowledge of the configuration of the conduit system.


    Directory of Open Access Journals (Sweden)

    G. V. Kazko


    Full Text Available Different ways of defining the characteristics of Antarctic subglacialLakeVostokcirculation are considered. The disadvantages of hydrodynamic models using the hydrostatic approximation exposed to analysis. Differential equations and boundary conditions of three-dimensional nonhydrostatic model in terms vorticity–vector potential, specially developed for the modelling of the lake circulation are presented. 3D model passed through the testing by means simulations of convective currents in the simple-form reservoirs. On the basis of the seismic data on the thickness of a glacier and bathimetry of the lake the computational domain approximating a water body ofLakeVostokis constructed. Some results of modeling of the convective processes in the lake, obtained at the initial stage of circulation evolution using finite-difference grid with a spatial resolution of 8000 × 1500 ×30 mare shown.

  12. Subglacial sediment mechanics investigated by computer simulation of granular material

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Tulaczyk, Slawek

    to the mechanical nonlinearity of the sediment, internal porosity changes during deformation, and associated structural and kinematic phase transitions. In this presentation, we introduce the Discrete Element Method (DEM) for particle-scale granular simulation. The DEM is fully coupled with fluid dynamics....... The numerical method is applied to better understand the mechanical properties of the subglacial sediment and its interaction with meltwater. The computational approach allows full experimental control and offers insights into the internal kinematics, stress distribution, and mechanical stability. During...... by linear-viscous sediment movement. We demonstrate how channel flanks are stabilized by the sediment frictional strength. Additionally, sediment liquefaction proves to be a possible mechanism for causing large and episodic sediment transport by water flow. Though computationally intense, our coupled...

  13. Investigating the effect of plate-mantle interaction in basin creation and associated drainage systems: insights from the North West Shelf of Australia (United States)

    Morón, S.; Gallagher, S. J.; Moresi, L. N.; Salles, T.; Rey, P. F.; Payenberg, T.


    The effect of plate-mantle dynamics on surface topography has increasingly being recognized. This concept is particularly useful for the understanding of the links between plate-mantle dynamics, continental break up and the creation of sedimentary basins and their associated drainage systems. To unravel these links back in time we present an approach that uses numerical models and the geological record. The sedimentary basins of the North West Shelf (NWS) of Australia contain an exceptional record of the Permian to early Cretaceous polyphased rifting of Australia from Greater India, which is in turn associated with the breakup of Gondwana. This record and the relative tectonic quiescence of the Australian Continent since the Late Cretaceous make the NWS a great natural laboratory for investigating the interaction between mantle dynamics, plate tectonics and drainage patterns. Furthermore, as a result of the extensive petroleum exploration and production in the area a uniquely large dataset containing seismic, lithologic, biostratigraphic and detrital zircon information is already available. This study will first focus on augmenting zircon datasets to refine the current conceptual models of paleodrainage systems associated with the NWS. Current conceptual models of drainage patterns suggest the previous existance of large transcontinental rivers that transported sediments from Antarctica and India, rather than from more proximal Australian sources. From a mass-balance point of view this model seems reasonable, as large transcontinental rivers would be required to transport the significant volume of sediments that are deposited in the thick (15km) sedimentary sequences of the NWS. Coupling of geodynamic (Underworld) and landscape-dynamics (Badlands) models will allow us to numerically test the likelihood of this conceptual model and also to present and integrated approach to investigate the link between deep Earth processes and surficial processes.

  14. Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations

    Directory of Open Access Journals (Sweden)

    Pierre-Marie Lefeuvre


    Full Text Available We used a finite element model to interpret anti-correlated pressure variations at the base of a glacier to demonstrate the importance of stress redistribution in the basal ice. We first investigated two pairs of load cells installed 20 m apart at the base of the 210 m thick Engabreen glacier in Northern Norway. The load cell data for July 2003 showed that pressurisation of a subglacial channel located over one load cell pair led to anti-correlation in pressure between the two pairs. To investigate the cause of this anti-correlation, we used a full Stokes 3D model of a 210 m thick and 25–200 m wide glacier with a pressurised subglacial channel represented as a pressure boundary condition. The model reproduced the anti-correlated pressure response at the glacier bed and variations in pressure of the same order of magnitude as the load cell observations. The anti-correlation pattern was shown to depend on the bed/surface slope. On a flat bed with laterally constrained cross-section, the resulting bridging effect diverted some of the normal forces acting on the bed to the sides. The anti-correlated pressure variations were then reproduced at a distance >10–20 m from the channel. In contrast, when the bed was inclined, the channel support of the overlying ice was vertical only, causing a reduction of the normal stress on the bed. With a bed slope of 5 degrees, the anti-correlation occurred within 10 m of the channel. The model thus showed that the effect of stress redistribution can lead to an opposite response in pressure at the same distance from the channel and that anti-correlation in pressure is reproduced without invoking cavity expansion caused by sliding.

  15. Testing the influence of subglacial erosion on the long-term evolution and stability of continental ice sheets using numerical modelling (United States)

    Swift, D. A.; Egholm, D. L.; Brædstrup, C. F.; Cook, S.; Livingstone, S. J.; Clark, C.; Patton, H.; Ely, J.


    Focussed erosion beneath continental ice sheets promotes efficient evacuation of ice along fast-flowing marine outlet glacier systems. Theory indicates that bed profiles should tend toward uniformly overdeepened geometries that will reduce ice sheet stability because (a) grounding lines situated on negative slopes are vulnerable to catastrophic retreat and (b) grounding-line stability is sensitive to ice velocity, meaning grounding lines should become unstable as overdeepening causes subglacial water pressures and basal sediment thickness and continuity to increase. This suggests a conceptual model of ice-bed evolution in which ice sheets are self-destructive, because bed erosion reduces equilibrium ice sheet volume and extent. However, many outlet glacier and ice stream systems possess complex bed topographies, raising questions about the nature of subglacial landscape evolution that have major implications for our understanding of ice sheet evolution and stability. For example, a contrasting model of ice-bed evolution in which strong ice-erosion feedbacks produce multiple overdeepenings might enhance ice sheet stability, because numerous bed undulations should resist fast ice flow and impede grounding line retreat. We therefore explore the possible glaciological significance of contrasting models of subglacial landscape evolution using a higher-order ice sheet model (iSOSIA) and assess the implications for the evolution and stability of continental ice sheets. The results will also aid understanding of contemporary ice sheet stability and identify weaknesses in process understanding that will aid further development of ice-erosion models.

  16. Agricultural Drainage Well Intakes (United States)

    Iowa State University GIS Support and Research Facility — Locations of surface intakes for registered agriculture drainage wells according to the database maintained by IDALS. Surface intakes were located from their...

  17. Dismal Swamp Drainage Patterns (United States)

    US Fish and Wildlife Service, Department of the Interior — The natural hydrolics of the Chesapeake Drainage Basin, which has its inception at the crest of the Appalachian mountain range, the waters flowing across the surface...

  18. Percutaneous Abscess Drainage (United States)

    ... and devices that monitor your heart beat and blood pressure. top of page How is the procedure performed? Image-guided, minimally invasive procedures such as percutaneous abscess drainage are most ...

  19. Surface Water & Surface Drainage (United States)

    Earth Data Analysis Center, University of New Mexico — This data set contains boundaries for all surface water and surface drainage for the state of New Mexico. It is in a vector digital data structure digitized from a...

  20. Geochemical behavior of an acid drainage system: the case of the Amarillo River, Famatina (La Rioja, Argentina). (United States)

    Lecomte, K L; Maza, S N; Collo, G; Sarmiento, A M; Depetris, P J


    The Amarillo River (Famatina range, Argentina, ~29° S and ~67° W) is unusual because acid mine drainage (AMD) is superimposed on the previously existing acid rock drainage (ARD) scenario, as a Holocene paleolake sedimentary sequence shows. In a markedly oxidizing environment, its water is currently ferrous and of the sulfate-magnesium type with high electrical conductivity (>10 mS cm(-1) in uppermost catchments). At the time of sampling, the interaction of the mineralized zone with the remnants of mining labors determined an increase in some elements (e.g., Cu ~3 to ~45 mg L(-1); As ~0.2 to ~0.5 mg L(-1)). Dissolved concentrations were controlled by pH, decreasing significantly by precipitation of neoformed minerals (jarosite and schwertmannite) and subsequent metal sorption (~700 mg kg(-1) As, 320 mg kg(-1) Zn). Dilution also played a significant role (i.e., by the mixing with circumneutral waters which reduces the dissolved concentration and also enhances mineral precipitation). Downstream, most metals exhibited a significant attenuation (As 100 %, Fe 100 %, Zn 99 %). PHREEQC-calculated saturation indices (SI) indicated that Fe-bearing minerals, especially schwertmannite, were supersaturated throughout the basin. All positive SI increased through the input of circumneutral water. PHREEQC inverse geochemical models showed throughout the upper and middle basin, that about 1.5 mmol L(-1) of Fe-bearing minerals were precipitated. The modeling exercise of mixing different waters yielded results with a >99 % of correlation between observed and modeled data.


    Directory of Open Access Journals (Sweden)

    L. Zhang


    Full Text Available In GIS and in terrain analysis, drainage systems are important components. Due to local topography and subsurface geology, a drainage system achieves a particular drainage pattern based on the form and texture of its network of stream channels and tributaries. Drainage pattern recognition helps to provide a qualitative description of the terrain for analysis and classification and is useful for terrain modelling and visualization and applications in environment. Much research has been done on the description of drainage patterns in geography and hydrology. However automatic drainage pattern recognition in river networks is not well developed. This paper introduces a method based on geometric quantitative indicators to recognize drainage patterns in a river network automatically. Experiment results are presented and discussed.

  2. Spinitectus osorioi (Nematoda: Cystidicolidae in the Mexican endemic fish Atherinella alvarezi (Atherinopsidae from the Atlantic River drainage system in Chiapas, Southern Mexico

    Directory of Open Access Journals (Sweden)

    František Moravec


    Full Text Available Specimens of Spinitectus osorioi Choudhury and Pérez-Ponce de León, an intestinal nematode species previously considered to be specific to Chirostoma spp and endemic to some lakes in the Pacific drainage in Michoacán, were collected from the freshwater fish Atherinella alvarezi (Díaz-Pardo (Atherinopsidae of the Michol River near Palenque, Chiapas, Southern Mexico, which belongs to the Atlantic drainage system. Studies using light and scanning electron microscopy revealed some taxonomically important, previously unreported or erroneously reported features of S. osorioi, such as the location of the vulva, the actual number and distribution of postanal papillae and phasmids and the presence of a short median cuticular ridge anterior to the cloacal opening (in addition to two long subventral ridges. The recorded somewhat shorter spicules (420-465 and 105-111 μm and mostly smaller eggs (33-36 × 18-20 μm as compared to the original species description may be due to a different type of host, geographical region or generally smaller body measurements of these specimens. These biometrical differences are considered to be within the limits of the intraspecific variability of S. osorioi. A key to species of Spinitectus parasitizing freshwater fishes in Mexico is provided.

  3. Hydrologic budget of the late Oligocene Lake Creede and the evolution of the upper Rio Grande drainage system (United States)

    Barton, Paul B.; Steven, Thomas A.; Hayba, Daniel O.


    drilling) formed in an euxinic environment. This argues against a persistent early playa, although evaporative accumulation of brine was inevitable. When the rate of resurgance was rapid relative to sedimentary infilling, the lake would have been deep (i.e., bordered by bedrock rather than sedimentary fans). The geomorphic evolution of the Creede caldera and its watershed tracks a two-phase topographic history, the first the Oligocene through Miocene, and the second for Pliocene to the recent. In Oligocene time, the San Juan volcanic field was a hydrologically immature, gently undulating, and outward sloping, constructional volcanic plateau straddling the ancient Continental Divide. West of the Creede caldera, a dendritic drainage discharged northeastward into ancestral Cebolla Creek (a tributary of the ancestral Gunnison River) through an early stage of the Clear Creek graben in the vicinity of Spring Creek Pass. Miocene basalt choked, but did not reconstruct, the drainage. By the end of Miocene time a mature topography of moderate relief developed, exposing some of the higher ores in the Creede district to weathering. In the late Miocene-early Pliocene time the San Juan Mountains were uplifted and titled eastward; the ancestral Rio Grande was revitalized and cut deeply into the older terrain, excavating much of the accessible sediment from the moat of the Creede caldera and exposing successively lowe levels in the Creede district to oxidation. Simultaneously, the southeast end of the Clear Creek graben was reactivated and breached the southwest wall of the Creede caldera. The rejuvenated Rio Grande captured the formerly northeast-directed headwaters of ancestral Cebolla Creek, shifting more than 1000 km2 from the Pacific-directed drainage to the Atlantic. The water budget for ancient Lake Creede was strictly limited by the early stages of the fist geomorphic cycle; the modern water budget is the product of the second cycle.

  4. Jökulhlaups in Iceland : sources, release and drainage


    Björnsson, Helgi


    Jökulhlaups in Iceland may originate from marginal or subglacial sources of water melted by atmospheric processes, permanent geothermal heat or volcanic eruptions. Glacier-volcano interactions produce meltwater that either drains toward the glacier margin or accumulates in subglacial lakes. Accumulated meltwater drains periodically in jökulhlaups from the subglacial lakes and occasionally during volcanic eruptions. During the 20th century 15 subglacial volcanic eruptions (10 major and 5 minor...

  5. Unrest at Bárdarbunga: Preparations for possible flooding due to subglacial volcanism (United States)

    Hardardottir, Jorunn; Roberts, Matthew; Pagneux, Emmanuel; Einarsson, Bergur; Thorarinsdottir, Tinna; Johannesson, Tomas; Sigurdsson, Oddur; Egilson, David; Sigurdsson, Gunnar; Imo hydrological-monitoring-team


    Located partly beneath northwest Vatnajökull, Iceland, the Bárdarbunga volcanic system comprises an ice-capped central volcano and a fissure swarm extending beyond the ice margin. During the last 1100 years the volcano has erupted on at least 26 occasions. Outburst floods (jökulhlaups) on a scale of >100,000 m3 s-1 are known to have occurred during major explosive eruptions. Repeated jökulhlaups from Bárdarbunga have inundated the Jökulsá á Fjöllum River, which drains over 200 km northwards from the Dyngjujökull outlet glacier to the north coast of Iceland. Depending on the location of the eruption within the 80 km2 caldera, jökulhlaups could also flow northwards along Skjálfandafljót River and towards west and southwest into present-day tributaries of the extensively hydropower-harnessed Thjórsá River. On 16 August 2014, an intense earthquake swarm began within the Bárdarbunga caldera. Seismicity propagated from the caldera, extending ~10 km northwards of the ice margin where a fissure eruption developed in late August and remains ongoing in early January 2015. In connection with the lateral migration of magma from the caldera, the ice surface of Bárdarbunga has lowered by over 60 m; also associated with increased geothermal heat on the caldera rim, as manifested by the development of ice-surface depressions. In preparation for a subglacial eruption in the Bárdarbunga volcanic system, the Icelandic Meteorological Office (IMO) has made several assessments of likely hydrological hazards. Assessments were undertaken on Jökulsá á Fjöllum and Skjálfandafljót at key locations where preliminary evacuation plans for populated areas were made in cooperation with the local police. Floodwater extent was estimated for key infrastructures, such as bridges, telecommunication and power lines for maximum discharge levels ranging from 3,000 to 20,000 m3 s-1. The estimations were made using either simple Manning's calculations or HEC-RAS modelling

  6. Analysis of effects of climate change on runoff in an urban drainage system: a case study from Seoul, Korea. (United States)

    Jung, M; Kim, H; Mallari, K J B; Pak, G; Yoon, J


    Both water quantity and quality are impacted by climate change. In addition, rapid urbanization has also brought an immeasurable loss of life and property resulting from floods. Hence, there is a need to predict changes in rainfall events to effectively design stormwater infrastructure to protect urban areas from disaster. This study develops a framework for predicting future short duration rainfall intensity and examining the effects of climate change on urban runoff in the Gunja Drainage Basin. Non-stationarities in rainfall records are first analysed using trend analysis to extrapolate future climate change scenarios. The US Environmental Protection Agency Storm Water Management Model (SWMM) was used for single event simulation of runoff quantity from the study area. For the 1-hour and 24-hour durations, statistically significant upward trends were observed. Although the 10-minute duration was only nearly significant at the 90% level, the steepest slope was observed for this short duration. Moreover, it was observed that the simulated peak discharge from SWMM increases as the short duration rainfall intensity increases. The proposed framework is thought to provide a means to review the current design of stormwater infrastructures to determine their capacity, along with consideration of climate change impact.

  7. Subglacial sediment provenance and transport in West Antarctica from micropaleontologic analysis of Subglacial Lake Whillans and the upstream sectors of the Whillans and Kamb ice streams (United States)

    Scherer, Reed; Coenen, Jason; Warny, Sophie


    The WISSARD (Whillans Ice Stream Subglacial Access Research Drilling) project recovered sediment cores from Subglacial Lake Whillans (SLW) in West Antarctica. We report preliminary micropaleontological analyses of SLW sediments, augmented by analysis of sediments previously recovered from beneath the upstream camps of the Whillans Ice Stream (WIS) and Kamb Ice Stream (KIS). Microfossils in these sediments (notably diatoms, sponge spicules, and organic-walled palynomorphs), include information regarding sediment transport, subglacial physical processes and ice sheet history. Absolute abundance (particles per gram dry sediment) of identifiable diatoms and diatom fragments in different size classes were calculated to compare and contrast each environment. Sponge spicules are being analyzed for taphonomic effects from subglacial transport and shearing. Palynomorphs are analyzed for abundance, diversity, and source rock ages. In SLW the upper 30 cm is softer and more water-rich than the underlying sediments. However, no statistically significant variation in microfossil and fragment abundance or taphonomy is noted in these diamictons, which is in agreement with the stratigraphic homogeneity evident from geochemical and geological analyses performed to date. SLW contains 1.52x106 to 1.13x107 diatom fragments per gram, compared with 6.43x106 to 4.63x108 at upstream WIS and 6.13 107 to 1.58x108 at KIS. Whole diatoms are orders of magnitude lower in concentration. Low abundance and poor preservation of diatoms and spicules at SLW suggests relatively long distance transport from their marine sediment source, with evidence of high shear strain, following the subglacial shearing index of Scherer et al. (2004). Upper Miocene diatoms dominate all samples analyzed, though older and younger diatoms are noted as well. The WIS samples exhibit the highest diversity of diatoms, including Paleogene freshwater diatoms. KIS sediments have the highest abundance of whole diatoms, but they


    Directory of Open Access Journals (Sweden)

    S. V. Popov


    Full Text Available The results of the remote sensing which carried out in the LakeVostokarea are discussed in the paper. A.P. Kapitsa and O.G. Sorokhtin started the geophysical researches in this area in 1950s. Satellite altimetry data, which analyzed in 1990s yielded to the discovering of the LakeVostok. After that, PMGE and RAE started the systematic studying of this natural phenomenon by seismic and radio-echo sounding. Total, 318 seismic soundings and 5190 kmof the radio-echo profiles has been collected by 2008. Special precise measurements which carried out in the 5G-1 borehole vicinity are resulted in the ice thickness over Vostok Station is 3760±30 mby seismic and 3775±15 mby radio-echo sounding. Thus, the error of geophysical measurements is less than 0.3%. The Russian investigations are resulted in definition the border of the lake, the discovering of 56 subglacial water caves around the lake and compilation the maps including ice thickness, ice base and bedrock topography and the depth of the lake. Average depth of the LakeVostokis about 400 m; water volume is 6100 km3. After 2008, the remote sensing works have been concentrated to the studying of the bottom sediments by refraction seismic technique. The firsts result shown that the bottom sediments thickness varies from 400 to1200 m.

  9. Surface Features Parameterization and Equivalent Roughness Height Estimation of a Real Subglacial Conduit in the Arctic (United States)

    Chen, Y.; Liu, X.; Manko ff, K. D.; Gulley, J. D.


    The surfaces of subglacial conduits are very complex, coupling multi-scale roughness, large sinuosity, and cross-sectional variations together. Those features significantly affect the friction law and drainage efficiency inside the conduit by altering velocity and pressure distributions, thus posing considerable influences on the dynamic development of the conduit. Parameterizing the above surface features is a first step towards understanding their hydraulic influences. A Matlab package is developed to extract the roughness field, the conduit centerline, and associated area and curvature data from the conduit surface, acquired from 3D scanning. By using those data, the characteristic vertical and horizontal roughness scales are then estimated based on the structure functions. The centerline sinuosities, defined through three concepts, i.e., the traditional definition of a fluvial river, entropy-based sinuosity, and curvature-based sinuosity, are also calculated and compared. The cross-sectional area and equivalent circular diameter along the centerline are also calculated. Among those features, the roughness is especially important due to its pivotal role in determining the wall friction, and thus an estimation of the equivalent roughness height is of great importance. To achieve such a goal, the original conduit is firstly simplified into a straight smooth pipe with the same volume and centerline length, and the roughness field obtained above is then reconstructed into the simplified pipe. An OpenFOAM-based Large-eddy-simulation (LES) is then performed based on the reconstructed pipe. Considering that the Reynolds number is of the order 106, and the relative roughness is larger than 5% for 60% of the conduit, we test the validity of the resistance law for completely rough pipe. The friction factor is calculated based on the pressure drop and mean velocity in the simulation. Working together, the equivalent roughness height can be calculated. However, whether the

  10. Ice-Dammed Lake Drainage Evolution at Russell Glacier, West Greenland

    Directory of Open Access Journals (Sweden)

    Jonathan L. Carrivick


    Full Text Available KEY POINTS/HIGHLIGHTSTwo rapid ice-dammed lake drainage events gauged and ice dam geometry measured.A melt enlargement model is developed to examine the evolution of drainage mechanism(s.Lake temperature dominated conduit melt enlargement and we hypothesize a flotation trigger.Glaciological and hydraulic factors that control the timing and mechanisms of glacier lake outburst floods (GLOFs remain poorly understood. This study used measurements of lake level at 15 min intervals and known lake bathymetry to calculate lake outflow during two GLOF events from the northern margin of Russell Glacier, west Greenland. We used measured ice surface elevation, interpolated subglacial topography and likely conduit geometry to inform a melt enlargement model of the outburst evolution. The model was tuned to best-fit the hydrograph rising limb and timing of peak discharge in both events; it achieved Mean Absolute Errors of <5%. About one third of the way through the rising limb, conduit melt enlargement became the dominant drainage mechanism. Lake water temperature, which strongly governed the enlargement rate, preconditioned the high peak discharge and short duration of these floods. We hypothesize that both GLOFs were triggered by ice dam flotation, and localized hydraulic jacking sustained most of their early-stage outflow, explaining the particularly rapid water egress in comparison to that recorded at other ice-marginal lakes. As ice overburden pressure relative to lake water hydraulic head diminished, flow became confined to a subglacial conduit. This study has emphasized the inter-play between ice dam thickness and lake level, drainage timing, lake water temperature and consequently rising stage lake outflow and flood evolution.

  11. Environmental effects on the aquatic system and metal discharge to the Mediterranean Sea from a near-neutral zinc-ferrous sulfate mine drainage (United States)

    Frau, Franco; Medas, Daniela; Da Pelo, Stefania; Wanty, Richard B.; Cidu, Rosa


    After mine closure in the 1980s and subsequent shutdown of the dewatering system, groundwater rebound led to drainage outflow from the Casargiu gallery (Montevecchio mine, SW Sardinia, Italy) beginning in 1997. Mine drainage had pH 6.0 and dissolved concentrations of sulfate (5000 mg/L) and metals (e.g., 1000 mg/L Zn, 230 mg/L Fe, 150 mg/L Mn) much higher than those previously measured in groundwater under dewatering conditions. As compared with the first stages of rebound at Casargiu, a very high contamination level still persists after more than 15 years of flushing. Mine drainage (20–70 L/s; pH 6.0 ± 0.2; Zn-Mg-Ca-SO4 composition) flowed into the Rio Irvi. Abundant precipitation of amorphous Fe(III)-(oxy)hydroxides occurred. Moreover, sulfate-bearing green rust was observed to flocculate in the reach of the Rio Irvi where pH was still circumneutral. Water sampling along this stream for about 6 km almost to its mouth in the Mediterranean Sea showed a pH decrease from 6.0 to 4.0 and a significant removal of Fe (46 %) and As (96 %), while sulfate, Zn, Mn, Co, Ni, and Cd showed small variations downstream. Lead was initially adsorbed onto Fe(III)-(oxy)hydroxides, then desorbed as pH dropped below 5. The estimated amount of dissolved metals discharged into the Mediterranean Sea is significant (e.g., 900 kg/day Zn, 1.4 kg/day Cd, 5 kg/day Ni). In particular, a conservative estimation of the amount of Zn discharged to the sea is about 330 ton/year, which would correspond to 1.4 % of the global annual flux of dissolved Zn from uncontaminated rivers to the oceans.

  12. Subglacial bedforms and conditions associated with the 1991 surge of Skeidarárjökull, Iceland

    NARCIS (Netherlands)

    Waller, R.I.; Dijk, T. van; Knudson, O.


    Much previous research at surge-type glaciers has sought to identify features diagnostic of surge-type behaviour. However, in comparatively little work have subglacial landform-sediment characteristics been used to reconstruct changing basal processes and conditions during surge events. Subglacial

  13. Lacrimal drainage system obstruction associated to radioactive iodine therapy for thyroid carcinoma; Obstrucao de vias lacrimais associada ao tratamento radioiodoterapico de carcinoma de tireoide

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, Fabricio Lopes da; Lunardelli, Patricia; Matayoshi, Suzana, E-mail: [Setor de Plastica Ocular, Divisao de Clinica Oftalmologica, Universidade de Sao Paulo (HC/FM/USP), Sao Paulo (SP) (Brazil)


    Purpose: To report the finding of nasolacrimal drainage system obstruction associated with radio iodine therapy and to review clinical data and the surgical treatment outcome of this rare complication. Methods: We retrospectively analyzed ophthalmological data of patients with history of thyroid carcinoma that underwent radioactive iodine I-131 therapy and were referred to lacrimal surgery. Results: 17 patients with thyroid cancer treated with thyroidectomy and radioactive iodine I-131 therapy presented symptomatic nasolacrimal duct obstruction after 13.2 months following cancer treatment. 11 patients presented bilateral epiphora, 8 had lacrimal sac mucocele. Age range was 30 to 80 years, 10 patients had less than or equal to 49 years. The mean cumulative dose of radioiodine was 571mCi (range: 200-1200 mCi). Nasal obstruction symptoms and increased salivary glands were also present in 53% of patients. All subjects underwent dacryocystorhinostomy. Dilation of the lacrimal sac and increased intraoperative bleeding was also observed in 3 younger patients. Complete epiphora and dacryocystitis resolution after surgery occurred in 82.4%, and partial in 17.6% (3 patients that still presented unilateral relapse after correction of bilateral obstruction). Mean follow-up was 6 months (range: 2-24 months). Conclusions: Cumulative high dose of radioiodine, nasal and salivary gland dysfunction are associated with lacrimal drainage obstruction. We observed a great percentage of younger patients presenting dacryocystitis when compared to the idiopathic dacryostenosis. Radioactive iodine uptake by nasolacrimal duct mucosa with subsequent inflammation, edema and fibrosis seems to have a relationship to lacrimal duct obstruction. The knowledge of this complication is important for the study and proper management of these patients (author)

  14. Holocene ochreous lacustrine sediments within the Famatina Belt, NW Argentina: A natural case for fossil damming of an acid drainage system (United States)

    Maza, Santiago N.; Collo, Gilda; Astini, Ricardo A.; Nieto, Fernando; Nieto, José Miguel


    A 44 m-thick lacustrine succession of silty-clay banded ochres and subordinated sandstones, and conglomerates (known as the Corral Amarillo Formation) is superbly exposed within the Famatina Belt (Central Andes of Argentina) after deep entrenchment by the present-day Amarillo river due to strong recent uplifting and consequent relative drop in base level. The unusual ochreous-rich succession was produced by natural damming (3.48-3.54 14C kyr BP) of an acid drainage system linked to the alteration cap of polymetallic deposits. Facies of silty-clay ochre (wet season) and banded ochre (dry season) from the paleolacustrine setting are composed of jarosite + goethite and goethite respectively. Geochemically, these layers record high concentrations of Fe2O3 (25-55 wt. %) and trace elements (Cu, Zn, Co, As, and Mo with mean concentrations of 2759; 2467; 109; 375 and 116 ppm, respectively). Their origin is inferred from a comparative analysis with the present-day Amarillo river, which has a pH of ˜3, (SO4)2- concentrations of ˜5000 mg/l, and jarosite as the dominant phase, in the upper catchments. Waters downstream have pH values of 3-4.5, (SO4)2- concentrations of ˜3000-480 mg/l, and schwertmannite as the dominant phase. Thus goethite in the paleolake facies is likely related to schwertmannite transformation by an aging process, whereas jarosite is probably transported from the river but could also be associated with post-depositional formation regulated by variations in grain size and the pore fluid chemistry. The Corral Amarillo Formation offers a Natural model, which may be employed to infer the effect on nature of acid drainage of mineralized areas.

  15. Ear drainage culture (United States)

    ... a lab and placed on a special dish (culture media). The lab team checks the dish every day ... Medical findings based on ear anatomy Ear drainage culture ... PR. The clinician and the microbiology laboratory. In: Bennett JE, Dolin R, Blaser MJ, ...

  16. Glacial removal of late Cenozoic subglacially emplaced volcanic edifices by the West Antarctic ice sheet (United States)

    Behrendt, John C.; Blankenship, D.D.; Damaske, D.; Cooper, A. K.


    Local maxima of the horizontal gradient of pseudogravity from closely spaced aeromagnetic surveys over the Ross Sea, northwestern Ross Ice Shelf, and the West Antarctic ice sheet, reveal a linear magnetic rift fabric and numerous subcircular, high-amplitude anomalies. Geophysical data indicate two or three youthful volcanic edifices at widely separated areas beneath the sea and ice cover in the West Antarctic rift system. In contrast, we suggest glacial removal of edifices of volcanic sources of many more anomalies. Magnetic models, controlled by marine seismic reflection and radar ice-sounding data, allow us to infer that glacial removal of the associated late Cenozoic volcanic edifices (probably debris, comprising pillow breccias, and hyaloclastites) has occurred essentially concomitantly with their subglacial eruption. "Removal' of unconsolidated volcanic debris erupted beneath the ice is probably a more appropriate term than "erosion', given its fragmented, ice-contact origin. The exposed volcanoes may have been protected from erosion by the surrounding ice sheet because of more competent rock or high elevation above the ice sheet. -from Authors

  17. An isotopic model for basal freeze-on associated with subglacial upward flow of pore water (United States)

    Souchez, R.; Samyn, D.; Lorrain, R.; Pattyn, F.; Fitzsimons, S.


    Subglacial freezing in polar glaciers can have a significant dynamical effect. Recent studies have shown that freezing of pore water flowing upward through subglacial fine-grained sediments at the freezing interface and progression of this freezing front downward are responsible for fast ice flow stoppage in ice streams. The upward pore water flow leads to the formation of debris-bearing basal ice layers. A model for stable isotope composition, both in δD and δ18O, is developed for predicting the isotopic composition of the ice segregated by such a mechanism. The development of this isotopic model for water films present along the grains of the subglacial sediment predicts the absence of apparent fractionation for the ice formed. This prediction is tested against two East Antarctic outlet glaciers by studying the δD-δ18O relationships in the basal ice layers of these glaciers.

  18. A new methodology to simulate subglacial deformation of water saturated granular material

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Piotrowski, Jan A.


    can cause variations in the pore-fluid pressure. The pressure variations weaken or strengthen the granular phase, and in turn influence the distribution of shear strain with depth. In permeable sediments the strain distribution is governed by the grain-size distribution and effective normal stress...... of subglacial sediment to the shear stress of an overriding glacier. In this study, we present a new methodology designed to simulate subglacial deformation using a coupled numerical model for computational experiments on grain-fluid mixtures. The granular phase is simulated on a per-grain basis by the discrete......The dynamics of glaciers are to a large degree governed by processes operating at the ice-bed interface, and one of the primary mechanisms of glacier flow over soft unconsolidated sediments is subglacial deformation. However, it has proven difficult to constrain the mechanical response...

  19. EUS-guided drainage of pancreatic fluid collections using a novel lumen-apposing metal stent on an electrocautery-enhanced delivery system: a large retrospective study (with video). (United States)

    Rinninella, Emanuele; Kunda, Rastislav; Dollhopf, Markus; Sanchez-Yague, Andres; Will, Uwe; Tarantino, Ilaria; Gornals Soler, Joan; Ullrich, Sebastian; Meining, Alexander; Esteban, Josè Miguel; Enz, Thomas; Vanbiervliet, Geoffroy; Vleggaar, Frank; Attili, Fabia; Larghi, Alberto


    A lumen-apposing, self-expanding metal stent incorporated in an electrocautery-enhanced delivery system for EUS-guided drainage of pancreatic fluid collections (PFCs) recently has become available. The aim of this study was to analyze the safety and clinical effectiveness of this newly developed device in this clinical setting. This was a retrospective analysis of all consecutive patients with PFCs who underwent EUS-guided drainage using the study device in 13 European centers. Ninety-three patients with PFCs (80% with complex collections) underwent drainage using the study device. Penetration of the PFC was accomplished directly with the study device in 74.2% of patients, and successful stent placement was accomplished in all but 1 patient, mostly without fluoroscopic assistance. Direct endoscopic necrosectomy (DEN) was carried out in 31 of 52 cases (59.6%) of walled-off necrosis and in 2 of 4 cases (50%) of acute peripancreatic fluid collection. Complete resolution of the PFC was obtained in 86 cases (92.5%), with no recurrence during follow-up. Treatment failure occurred in 6 patients because of persistent infection requiring surgery (n = 3), perforation and massive bleeding caused by the nasocystic drainage catheter (NCDC) (n = 2), and the need for a larger opening to extract large necrotic tissue pieces (n = 1). Major adverse events occurred in 5 patients (perforation and massive bleeding caused by the NCDC in 2 patients, 1 pneumoperitoneum and 1 stent dislodgement during DEN, and 1 postdrainage infection) and were mostly not related to the drainage procedure. EUS-guided drainage with the electrocautery-enhanced delivery system is a safe, easy to perform, and a highly effective minimally invasive treatment modality for PFCs. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

  20. EUS-guided drainage of pancreatic fluid collections using a novel lumen-apposing metal stent on an electrocautery-enhanced delivery system : a large retrospective study (with video)

    NARCIS (Netherlands)

    Rinninella, Emanuele; Kunda, Rastislav; Dollhopf, Markus; Sanchez-Yague, Andres; Will, Uwe; Tarantino, Ilaria; Gornals Soler, Joan; Ullrich, Sebastian; Meining, Alexander; Esteban, Josè Miguel; Enz, Thomas; Vanbiervliet, Geoffroy; Vleggaar, FP; Attili, Fabia; Larghi, Alberto


    BACKGROUND AND AIMS: A lumen-apposing, self-expanding metal stent incorporated in an electrocautery-enhanced delivery system for EUS-guided drainage of pancreatic fluid collections (PFCs) recently has become available. The aim of this study was to analyze the safety and clinical effectiveness of

  1. Long-term subglacial sliding patterns based on a sliding law with cavitation

    DEFF Research Database (Denmark)

    Ugelvig, Sofie Vej; Egholm, D.L.

    In ice-sheet models and glacial landscape evolution models, subglacial sliding rates are often related to basal shear stress by a power-law. However, the power-law relationship implies that the subglacial bed can provide unlimited levels of basal drag as sliding rates increases, which is recogniz...... of cavitation on glacier sliding. Proc. R. Soc. A , 461, 609-627 (2005). Egholm et al. Modeling the flow of glaciers in steep terrains: The integrated second-order shallow ice approximation (iSOSIA). Journal of Geophysical Research, 116, F02012 (2011)....

  2. Feedbacks between subglacial dynamics and long-term glacial landscape evolution

    DEFF Research Database (Denmark)

    Brædstrup, Christian; Egholm, D.L.; Ugelvig, Sofie Vej

    computational experiments with a higher-order ice sheet model (Egholm et al., 2009) capable of simulating the long-term evolution of subglacial dynamics at a high spatial resolution. The orientation and magnitude of subglacial stress components depend not only on ice thickness and ice surface gradients...... associated to the level of cavitation (Iverson, 2012). The highly non-linear computational experiments are made possible by new and very efficient GPU-accelerated multigrid algorithms. The computational experiments show that higher-order stress effects associated with local changes to the bed gradient...

  3. Structural influence on the evolution of the pre-Eonile drainage system of southern Egypt: Insights from magnetotelluric and gravity data (United States)

    Roden, Jeff; Abdelsalam, Mohamed G.; Atekwana, Estella; El-Qady, Gad; Tarabees, Elhamy Aly


    The Wadi Kubbaniya in the Western Desert of Egypt north of the City of Aswan has been interpreted as the downstream continuation of the Wadi Abu Subeira, comprising an ancient W- and NW-flowing river system originating from the Precambrian crystalline rocks of the Red Sea Hills which were uplifted during the Miocene in association with the opening of the Red Sea. This drainage system is thought to have been active before the onset of the N-flowing Egyptian Nile which started ˜6 Ma with the Eonile phase; an event that resulted in carving of ˜1000 km long canyon (the Eonile canyon) extending from the Mediterranean Sea in the north to Aswan in the south due to the Messinian Salinity Crisis. This study utilizes geophysical data to examine the role of regional tectonics and local structures in controlling the evolution of the pre-Eonile drainage system. Magnetotelluric (MT) and gravity surveys were conducted along two ˜5 km-long profiles across the NW-trending Wadi Kubbaniya. Two-dimensional (2D) inversion of MT data and gravity models indicate the Wadi Kubbaniya is filled with loosely-consolidated sandstone and conglomerate that extend to a depth of ˜150-200 m into Cretaceous sandstone formations which overlie Precambrian crystalline rocks. These results were evaluated in terms of two end-member models; an incision model in which the 150-200 m thick sedimentary rocks were considered as being deposited within an incised valley that was carved into bedrock, or a structural model in which the sedimentary rocks are considered as filling a NW-trending graben controlled by normal faults that deform the Cretaceous sandstone formations and the underlying Precambrian crystalline rocks. Geological observations as well as supporting seismic data favor the interpretation that the Wadi Kubbaniya is a NW-trending graben similar to other extensional structures found 400 km northwest along-strike of Wadi Kubbaniya. These structures are impressively parallel to the western

  4. Wound Drainage Culture (For Parents) (United States)

    ... a Voice in Health Care Decisions Wound Drainage Culture KidsHealth > For Parents > Wound Drainage Culture Print A A A What's in this article? ... Have Questions What It Is A wound drainage culture is a test to detect germs such as ...

  5. Comparison between autologous blood transfusion drainage and closed-suction drainage/no drainage in total knee arthroplasty: a meta-analysis. (United States)

    Hong, Kun-Hao; Pan, Jian-Ke; Yang, Wei-Yi; Luo, Ming-Hui; Xu, Shu-Chai; Liu, Jun


    Autologous blood transfusion (ABT) drainage system is a new unwashed salvaged blood retransfusion system for total knee replacement (TKA). However, whether to use ABT drainage, closed-suction (CS) drainage or no drainage in TKA surgery remains controversial. This is the first meta-analysis to assess the clinical efficiency, safety and potential advantages regarding the use of ABT drains compared with closed-suction/no drainage. PubMed, Embase, and the Cochrane Library were comprehensively searched in March 2015. Fifteen randomized controlled trials (RCTs) were identified and pooled for statistical analysis. The primary outcome evaluated was homologous blood transfusion rate. The secondary outcomes were post-operative haemoglobin on days 3-5, length of hospital stay and wound infections after TKA surgery. The pooled data included 1,721 patients and showed that patients in the ABT drainage group might benefit from lower blood transfusion rates (16.59 % and 37.47 %, OR: 0.28 [0.14, 0.55]; 13.05 % and 16.91 %, OR: 0.73 [0.47,1.13], respectively). Autologous blood transfusion drainage and closed-suction drainage/no drainage have similar clinical efficacy and safety with regard to post-operative haemoglobin on days 3-5, length of hospital stay and wound infections. Autologous blood transfusion drainage offers a safe and efficient alternative to CS/no drainage with a lower blood transfusion rate. Future large-volume high-quality RCTs with extensive follow-up will affirm and update this system review.

  6. A gain-loss framework based on ensemble flow forecasts to switch the urban drainage-wastewater system management towards energy optimization during dry periods (United States)

    Courdent, Vianney; Grum, Morten; Munk-Nielsen, Thomas; Mikkelsen, Peter S.


    Precipitation is the cause of major perturbation to the flow in urban drainage and wastewater systems. Flow forecasts, generated by coupling rainfall predictions with a hydrologic runoff model, can potentially be used to optimize the operation of integrated urban drainage-wastewater systems (IUDWSs) during both wet and dry weather periods. Numerical weather prediction (NWP) models have significantly improved in recent years, having increased their spatial and temporal resolution. Finer resolution NWP are suitable for urban-catchment-scale applications, providing longer lead time than radar extrapolation. However, forecasts are inevitably uncertain, and fine resolution is especially challenging for NWP. This uncertainty is commonly addressed in meteorology with ensemble prediction systems (EPSs). Handling uncertainty is challenging for decision makers and hence tools are necessary to provide insight on ensemble forecast usage and to support the rationality of decisions (i.e. forecasts are uncertain and therefore errors will be made; decision makers need tools to justify their choices, demonstrating that these choices are beneficial in the long run). This study presents an economic framework to support the decision-making process by providing information on when acting on the forecast is beneficial and how to handle the EPS. The relative economic value (REV) approach associates economic values with the potential outcomes and determines the preferential use of the EPS forecast. The envelope curve of the REV diagram combines the results from each probability forecast to provide the highest relative economic value for a given gain-loss ratio. This approach is traditionally used at larger scales to assess mitigation measures for adverse events (i.e. the actions are taken when events are forecast). The specificity of this study is to optimize the energy consumption in IUDWS during low-flow periods by exploiting the electrical smart grid market (i.e. the actions are taken

  7. An iron-age cultural hiatus enigma: mega-flooding and human settlement abandonment over the last millennium in the Lanyang Drainage System, northeastern Taiwan (United States)

    Huang, Jyh-Jaan; Wei, Kuo-Yen; Löwemark, Ludvig; Song, Sheng-Rong; Huh, Chih-An; Chuang, Chih-Kai; Yang, Tien-Nan; Lee, Meng-Yang; Chen, Yu-Be; Lee, Teh-Quei


    Active tectonic activities and frequent typhoon landfalls make Taiwan unique in having very high rates of uplift, precipitation, denudation and sedimentation. Particularly, intense rainfall associated with typhoons often causes flooding, large-scale landslides, and debris flows in river systems. Such natural disasters have affected human societies both at present and in the past; the Typhoon Morakot in 2009 may serve as a modern example of such events. Kiwulan is a newly discovered archaeological site from the Iron Age situated on the Lanyang Plain in NE Taiwan. In the deposits from this society, a cultural hiatus centered around 1200-1500 cal. yr AD is found, suggesting that the settlement was abandoned for a period of a few hundred years before being recolonized. Until now it has remained a mystery what caused this cultural hiatus. This study assembles radiocarbon dates of upland river terraces, organic proxies in flood plain lake sediments, and content of wood shreds in nearby marine sediments from the continental slope off NE Taiwan. These records are synthesized to infer the frequency and magnitude of ancient flood events over the past 1250 years in the Lanyang Drainage System in northeastern Taiwan. Alluvial fan terraces distributed along the banks of the upper Lanyang River are considered to be the results of ancient debris flow events, and their radiocarbon dates fall in two time ranges: 850-1100 and 1400-1600 cal. yr AD. Organic proxies which representing terrestrial organic input were measured from bulk sediments of Lake Dahu and Lake Meihua in the Lanyang Plain. Peak values of TOC, C/N ratio and organic indicator (inc/coh) from Itrax-XRF core scanner measurements are conspicuous during 900-950, and 1400-1500 cal. yr AD, implying frequent flood events. Moreover, abundance peaks of wood shreds and peaks in the C/N ratio in marine box core ORI-801-7A from the continental slope SE of the Lanyang Plain are dated to about 950-1050 and 1450-1550 cal. yr AD

  8. Refined broad-scale sub-glacial morphology of Aurora Subglacial Basin, East Antarctica derived by an ice-dynamics-based interpolation scheme

    Directory of Open Access Journals (Sweden)

    J. L. Roberts


    Full Text Available Ice thickness data over much of East Antarctica are sparse and irregularly distributed. This poses difficulties for reconstructing the homogeneous coverage needed to properly assess underlying sub-glacial morphology and fundamental geometric constraints on sea level rise. Here we introduce a new physically-based ice thickness interpolation scheme and apply this to existing ice thickness data in the Aurora Subglacial Basin region. The skill and robustness of the new reconstruction is demonstrated by comparison with new data from the ICECAP project. The interpolated morphology shows an extensive marine-based ice sheet, with considerably more area below sea-level than shown by prior studies. It also shows deep features connecting the coastal grounding zone with the deepest regions in the interior. This has implications for ice sheet response to a warming ocean and underscores the importance of obtaining additional high resolution data in these marginal zones for modelling ice sheet evolution.

  9. Hydrodynamic Performances of Air-Water Flows in Gullies with and without Swirl Generation Vanes for Drainage Systems of Buildings

    National Research Council Canada - National Science Library

    Der-Chang Lo; Jin-Shuen Liou; Shyy Woei Chang


    ...) image and optical systems for experimental study, the mechanism of air entrainment by vortex, the temporal variations of airflow pressure, the trajectories of drifting air bubbles and the self...

  10. Subglacial lake matters: piracy on a divide between thawed and frozen bed (United States)

    Carter, S. P.; Bougamont, M. H.; Christoffersen, P.; Fricker, H. A.; Lipscomb, W. H.; Price, S. F.


    The two most populated active subglacial lake districts in Antarctica, upper Kamb Ice Stream and lower Whillans Ice Stream, occur along boundaries between where temperature models predict net basal freezing and net basal accretion. This occurs in part due to a basal traction contrast, which creates a ridge in the ice surface and creates a pressure seal; this impedes the downstream movement of water until a subglacial lake flood occurs. Here we use a model for basal water routing, which incorporates subglacial floods and a realistic term for effective pressure, to explore the ability of these floods to provide water to areas of net basal accretion and thus maintain basal lubrication. We hypothesize that these floods can distribute sufficient water to most of the regions experiencing net basal freezing; the exception being those nearest to the lakes themselves, Discharge in these regions likely occurs via narrow subglacial conduits. Over time this will cause ice downstream of the dam to thicken and pre-flood lake levels to increase until water ultimately exits the lake via an alternate route i.e. water piracy. Once piracy occurs, water is no longer supplied along the former flowpath and ice stream shutdown accelerates. We conclude that the formation and quasi-periodic flooding of lakes at the basal melt/ basal freezing boundary is a critical process in accelerating ice stream shutdown.

  11. A balanced water layer concept for subglacial hydrology in large-scale ice sheet models

    Directory of Open Access Journals (Sweden)

    S. Goeller


    Full Text Available There is currently no doubt about the existence of a widespread hydrological network under the Antarctic Ice Sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux–basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

  12. A balanced water layer concept for subglacial hydrology in large scale ice sheet models (United States)

    Goeller, S.; Thoma, M.; Grosfeld, K.; Miller, H.


    There is currently no doubt about the existence of a wide-spread hydrological network under the Antarctic ice sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain inspired by the Gamburtsev Mountains, Antarctica. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux-basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out, that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

  13. Viable cold-tolerant iron-reducing microorganisms in geographically diverse subglacial environments (United States)

    Nixon, Sophie L.; Telling, Jon P.; Wadham, Jemma L.; Cockell, Charles S.


    Subglacial environments are known to harbour metabolically diverse microbial communities. These microbial communities drive chemical weathering of underlying bedrock and influence the geochemistry of glacial meltwater. Despite its importance in weathering reactions, the microbial cycling of iron in subglacial environments, in particular the role of microbial iron reduction, is poorly understood. In this study we address the prevalence of viable iron-reducing microorganisms in subglacial sediments from five geographically isolated glaciers. Iron-reducing enrichment cultures were established with sediment from beneath Engabreen (Norway), Finsterwalderbreen (Svalbard), Leverett and Russell glaciers (Greenland), and Lower Wright Glacier (Antarctica). Rates of iron reduction were higher at 4 °C compared with 15 °C in all but one duplicated second-generation enrichment culture, indicative of cold-tolerant and perhaps cold-adapted iron reducers. Analysis of bacterial 16S rRNA genes indicates Desulfosporosinus were the dominant iron-reducing microorganisms in low-temperature Engabreen, Finsterwalderbreen and Lower Wright Glacier enrichments, and Geobacter dominated in Russell and Leverett enrichments. Results from this study suggest microbial iron reduction is widespread in subglacial environments and may have important implications for global biogeochemical iron cycling and export to marine ecosystems.

  14. Inventory of drainage wells and potential sources of contaminants to drainage-well inflow in Southwest Orlando, Orange County, Florida (United States)

    Taylor, George Fred


    Potential sources of contaminants that could pose a threat to drainage-well inflow and to water in the Floridan aquifer system in southwest Orlando, Florida, were studied between October and December 1990. Drainage wells and public-supply wells were inventoried in a 14-square-mile area, and available data on land use and activities within each drainage well basin were tabulated. Three public-supply wells (tapping the Lower Floridan aquifer) and 38 drainage wells (open to the Upper Floridan aquifer) were located in 17 drainage basins within the study area. The primary sources of drainage-well inflow are lake overflow, street runoff, seepage from the surficial aquifer system, and process-wastewater disposal. Drainage-well inflow from a variety of ares, including resi- dential, commercial, undeveloped, paved, and industrial areas, are potential sources of con- taminants. The four general types of possible contaminants to drainage-well inflow are inorganic chemicals, organic compounds, turbidity, and microbiological contaminants. Potential contami- nant sources include plant nurseries, citrus groves, parking lots, plating companies, auto- motive repair shops, and most commonly, lake- overflow water. Drainage wells provide a pathway for contaminants to enter the Upper Floridan aquifer and there is a potential for contaminants to move downward from the Upper Floridan to the Lower Floridan aquifer.

  15. Bilateral anomalous drainage of the posterior divisions of renal veins into the azygos venous system in a 20-year-old woman: a case report. (United States)

    Pallangyo, Pedro; Lyimo, Frederick; Nicholaus, Paulina; Masatu, Stephano; Janabi, Mohamed


    Renal vein anomalies are relatively infrequent and generally asymptomatic. Preoperative knowledge of such variants is, however, of paramount importance in several angiographic and surgical procedures including renal venography, renal vein sampling, spermatic embolization, and renal transplantation. Inadequate knowledge and failure to recognize such anatomic variations may lead to several operative hazards including hemorrhage, nephrectomy, and even death. We report a case of bilateral anomalous drainage of the posterior divisions of renal veins into the azygos venous system in a 20-year-old woman of African descent from Tanzania who presented to us with a 12-year history of recurrent anemia. She had anemia, a positive sickling test, and hemoglobin electrophoresis revealed a sickle cell trait (AS). She underwent computed tomography angiography of her chest and abdomen to rule out the presence of arteriovenous malformations. Aortography findings were normal but venography results revealed features of tortuously dilated azygos and hemiazygos veins each receiving blood from its respective posterior division of renal vein. Although venous anomalies are relatively infrequent and generally lack a clinical significance, a thorough understanding of embryologic development and its associated errors is of immense importance in equipping angiographers and surgeons to select appropriate interventional/operative techniques, anticipate risks, and prevent intervention-related complications.

  16. Diagnostic performance of the three-dimensional fast spin echo-Cube sequence in comparison with a conventional imaging protocol in evaluation of the lachrymal drainage system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Chen, Lang; Wang, Qiu-Xia; Zhu, Wen-Zhen; Luo, Xin; Peng, Li [Huazhong University of Science and Technology, Department of Radiology, Tongji Hospital, Wuhan (China); Liu, Rong [Huazhong University of Science and Technology, Department of Ophthalmology, Tongji Hospital, Wuhan (China); Xiong, Wei [GE Healthcare China Wuhan Office, Wuhan (China)


    To compare the three-dimensional (3D)-fast spin-echo (FSE)-Cube with a conventional imaging protocol in evaluation of dacryostenosis. Thirty-three patients with epiphora underwent examinations using Cube magnetic resonance dacryocystography (MRD) and a conventional protocol, which included 3D fast-recovery fast spin-echo (FRFSE) MRD and two-dimensional (2D)-FSE sequences at 3.0 T. Using lachrymal endoscopic findings as the reference standard, we calculated the sensitivity and specificity of both protocols for detecting lachrymal drainage system (LDS) obstruction and their accuracies in depicting the level of obstruction. Comparable coronal and axial images were selected for bot sequences. Two neuroradiologists graded paired images for blurring, artefacts, anatomic details, and overall image quality. The two methods showed no significant difference in sensitivity (89.5 % vs. 94.7 %; p =0.674), specificity (64.3 %; p =1) or accuracy (86.8 %; p =1) in detecting or depicting LDS obstruction. Blurring and artefacts were significantly better on 2D-FSE images (p <0.01 and p <0.05, respectively). Anatomic details were significantly better on Cube reformats (p <0.001). No significant difference existed in overall image quality (p >0.05). In comparison with the conventional protocol, Cube MRD demonstrates satisfactory image quality and similar diagnostic capability for cases of possible LDS disease. (orig.)

  17. Evaluating the Acid Mine Drainage Potential at Abosso Goldfields ...

    African Journals Online (AJOL)

    Occurrence of Acid Rock Drainae (ARD) affects both plants and animals that are present in a drainage system. In some base metal and coal mining environments, the presence of sulphide minerals especially pyrite and their exposure to oxygen and water may trigger Acid Mine Drainage (AMD). Evaluation of the potential for ...

  18. Simulating Effects of Drainage Design Parameters on Optimum Crop ...

    African Journals Online (AJOL)

    Agricultural water management system aims to provide crop water requirements to sustain optimum yield. Some of the factors influencing optimum crop yield are drainage design parameters in water-logged soils. Hence, the impact of drainage design parameters on optimum crop yield was examined. Field experimentation ...

  19. Drainage of curd


    Akkerman, J. C.


    Cheese making starts with transformation of the liquid milk into a gel by proteolytic enzymes and/or acid producing bacteria. The gel is cut into pieces. The protein matrix contracts, by which whey is expelled from the pieces, this process is called syneresis. The process of whey expulsion is enhanced by stirring and usually heating. Finally fairly rigid curd grains and a large amount of whey are obtained. The subsequent separation of whey and curd grains is called drainage of curd. ...

  20. Computationally efficient and flexible modular modelling approach for river and urban drainage systems based on surrogate conceptual models (United States)

    Wolfs, Vincent; Willems, Patrick


    Water managers rely increasingly on mathematical simulation models that represent individual parts of the water system, such as the river, sewer system or waste water treatment plant. The current evolution towards integral water management requires the integration of these distinct components, leading to an increased model scale and scope. Besides this growing model complexity, certain applications gained interest and importance, such as uncertainty and sensitivity analyses, auto-calibration of models and real time control. All these applications share the need for models with a very limited calculation time, either for performing a large number of simulations, or a long term simulation followed by a statistical post-processing of the results. The use of the commonly applied detailed models that solve (part of) the de Saint-Venant equations is infeasible for these applications or such integrated modelling due to several reasons, of which a too long simulation time and the inability to couple submodels made in different software environments are the main ones. Instead, practitioners must use simplified models for these purposes. These models are characterized by empirical relationships and sacrifice model detail and accuracy for increased computational efficiency. The presented research discusses the development of a flexible integral modelling platform that complies with the following three key requirements: (1) Include a modelling approach for water quantity predictions for rivers, floodplains, sewer systems and rainfall runoff routing that require a minimal calculation time; (2) A fast and semi-automatic model configuration, thereby making maximum use of data of existing detailed models and measurements; (3) Have a calculation scheme based on open source code to allow for future extensions or the coupling with other models. First, a novel and flexible modular modelling approach based on the storage cell concept was developed. This approach divides each

  1. Distinguishing high and low flow domains in urban drainage systems 2 days ahead using numerical weather prediction ensembles

    DEFF Research Database (Denmark)

    Courdent, Vianney Augustin Thomas; Grum, Morten; Mikkelsen, Peter Steen


    Precipitation constitutes a major contribution to the flow in urban storm- and wastewater systems. Forecasts of the anticipated runoff flows, created from radar extrapolation and/or numerical weather predictions, can potentially be used to optimize operation in both wet and dry weather periods....... However, flow forecasts are inevitably uncertain and their use will ultimately require a trade-off between the value of knowing what will happen in the future and the probability and consequence of being wrong. In this study we examine how ensemble forecasts from the HIRLAM-DMI-S05 numerical weather...... prediction (NWP) model subject to three different ensemble post-processing approaches can be used to forecast flow exceedance in a combined sewer for a wide range of ratios between the probability of detection (POD) and the probability of false detection (POFD). We use a hydrological rainfall-runoff model...

  2. Real Time Control strategies to reduce expansion of urban drainage systems. Case study: Lyngby-Taarbæk

    DEFF Research Database (Denmark)

    Meneses Ortega, Elbys Jose; Gaussens, Marion; Jakobsen, Carsten


    been planned to fulfil new environmental requirements. Two RTC methods are implemented in order to maintain the same combined sewer network performance while reducing the planned basin expansion, and consequently reducing the investment cost. A state-of-the-art global control scheme using a 2-hour...... overflow (CSO) discharges for small to medium rain events; while the desired performance of the system is achieved for big events. The rule-based strategy reduces significantly CSO, however DORA provides generally better results by using forecasting and riskbased approach. These results show...... that implementing RTC strategies during the design stages could reduce the elevated cost associated with UDS expansion while offering a similar or even better protection to the environment....

  3. Quasi-100 ky glacial-interglacial cycles triggered by subglacial burial carbon release

    Directory of Open Access Journals (Sweden)

    N. Zeng


    Full Text Available A mechanism is proposed in which climate, carbon cycle and icesheets interact with each other to produce a feedback that can lead to quasi-100 ky glacial-interglacial cycles. A central process is the burial and preservation of organic carbon by icesheets which contributes to the observed glacial-interglacial CO2 change (the glacial burial hypothesis, Zeng, 2003. Allowing carbon cycle to interact with physical climate, here I further hypothesize that deglaciation can be triggered by the ejection of glacial burial carbon when a major icesheet grows to sufficiently large size after a prolonged glaciation so that subglacial transport becomes significant. Glacial inception may be initiated by CO2 drawdown due to a relaxation from a high but transient interglacial CO2 value as the land-originated CO2 invades into deep ocean via thermohaline circulation and CaCO3 compensation. Also important for glacial inception may be the CO2 uptake by vegetation and soil regrowth in the previously ice-covered regions. When tested in a fully coupled Earth system model with comprehensive carbon cycle components and semi-empirical physical climate components, it produced under certain parameter regimes self-sustaining glacial-interglacial cycles with durations of 93 ky, CO2 changes of 90 ppmv, temperature changes of 6°C. Since the 100 ky cycles can not be easily explained by the Milankovitch astronomical forcing alone, this carbon-climate-icesheet mechanism provides a strong feedback that could interact with external forcings to produce the major observed Quaternary climatic variations. It is speculated that some glacial terminations may be triggered by this internal feedback while others by orbital forcing. Some observable consequences are highlighted that may support or falsify the theory.

  4. Characterization of limestone reacted with acid-mine drainage in a pulsed limestone bed treatment system at the Friendship Hill National Historical Site, Pennsylvania, USA

    Energy Technology Data Exchange (ETDEWEB)

    Hammarstrom, J.M.; Sibrell, P.L.; Belkin, H.E. [US Geological Survey, Reston, VA (United States)


    Armoring of limestone is a common cause of failure in limestone-based acid-mine drainage (AMD) treatment systems. Limestone is the least expensive material available for acid neutralization, but is not typically recommended for highly acidic, Fe-rich waters due to armoring with Fe(III) oxyhydroxide coatings. A new AMD treatment technology that uses CO{sub 2} in a pulsed limestone bed reactor minimizes armor formation and enhances limestone reaction with AMD. Limestone was characterized before and after treatment with constant flow and with the new pulsed limestone bed process using AMD from an inactive coal mine in Pennsylvania (pH = 2.9, Fe = 150 mg/l, acidity 1000 mg/l CaCO{sub 3}). In constant flow experiments, limestone is completely armored with reddish-colored ochre within 48 h of contact in a fluidized bed reactor. Effluent pH initially increased from the inflow pH of 2.9 to over 7, but then decreased to {lt}4 during the 48 h of contact. Limestone grains developed a rind of gypsum encapsulated by a 10- to 30-mum thick, Fe-Al hydroxysulfate coating. Armoring slowed the reaction and prevented the limestone from generating any additional alkalinity in the system. With the pulsed flow limestone bed process, armor formation is largely suppressed and most limestone grains completely dissolve resulting in an effluent pH of {gt}6 during operation. Limestone removed from a pulsed bed pilot plant is a mixture of unarmored, rounded and etched limestone grains and partially armored limestone and refractory mineral grains (dolomite, pyrite). Aluminium-rich zones developed in the interior parts of armor rims in both the constant flow and pulsed limestone bed experiments in response to pH changes at the solid/solution interface.

  5. Development of a novel CsA-PLGA drug delivery system based on a glaucoma drainage device for the prevention of postoperative fibrosis

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Zhaoxing; Yu, Xiaobo; Hong, Jiaxu; Liu, Xi [Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai 200031 (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai 200031 (China); Sun, Jianguo, E-mail: [Research Center, Eye & ENT Hospital, Fudan University, Shanghai 200031 (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai 200031 (China); State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200031 (China); Sun, Xinghuai, E-mail: [Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai 200031 (China); Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai 200031 (China)


    The formation of a scar after glaucoma surgery often leads to unsuccessful control of intraocular pressure, and should be prevented by using a variety of methods. We designed and developed a novel drug delivery system (DDS) comprising cyclosporine A (CsA) and poly(lactic-co-glycolic acid) (PLGA) based on a glaucoma drainage device (GDD) that can continuously release CsA to prevent postoperative fibrosis following glaucoma surgery. The CsA@PLGA@GDD DDS was observed by field emission scanning electron microscopy and revealed an asymmetric pore structure. Thermogravimetric analysis was performed to measure the weight loss and evaluate the thermal stability of the CsA@PLGA@GDD DDS. The in vitro drug release profile of the DDS was studied using high performance liquid chromatography, which confirmed that the DDS released CsA at a stable rate and maintained adequate CsA concentrations for a relatively long time. The biocompatibility of the DDS and the inhibitory effects on the postoperative fibrosis were investigated in vitro using rabbit Tenon's fibroblasts. The in vivo safety and efficacy of the DDS were examined by implanting the DDS into Tenon's capsules in New Zealand rabbits. Bleb morphology, intraocular pressure, anterior chamber reactions, and anterior chamber angiography were studied at a series of set times. The DDS kept the filtration pathway unblocked for a longer time compared with the control GDD. The results indicate that the CsA@PLGA@GDD DDS represents a safe and effective strategy for preventing scar formation after glaucoma surgery. - Highlights: • CsA@PLGA@GDD drug delivery system (DDS) was designed and prepared successfully. • The DDS released CsA at a stable rate for > 3 months. • The DDS kept filtration pathway unblocked for a longer time than control. • CsA@PLGA@GDD DDS prevented glaucoma scar formation as a safe and effective strategy.

  6. Tectonic and erosion-driven uplift in the Gamburtsev Subglacial Mountains of East Antarctica (United States)

    Ferraccioli, Fausto; Jordan, Tom; Watts, Tony; Bell, Robin; Jamieson, Stewart; Finn, Carol; Damaske, Detlef


    Understanding the mechanisms leading to intraplate mountain building remains a significant challenge in Earth Sciences compared to ranges formed along plate margins. The most enigmatic intraplate mountain range on Earth is the Gamburtsev Subglacial Mountains (GSM) located in the middle of the Precambrian East Antarctic Craton. During the International Polar Year, the AGAP project acquired 120,000 line km of new airborne geophysical data (Bell et al., 2011, Science) and seismological observations (Hansen et al., 2010, EPSL) across central East Antarctica. Models derived from these datasets provide new geophysical perspectives on crustal architecture and possible uplift mechanisms for the enigmatic GSM (Ferraccioli et al., 2011, Nature). The geophysical data define a 2,500-km-long Paleozoic to Mesozoic rift system in East Antarctica surrounding the GSM. A thick high-density lower crustal root is partially preserved beneath the range and has been interpreted as formed during the Proterozoic assembly of East Antarctica. Rifting could have triggered phase/density changes at deep crustal levels, perhaps restoring some of the latent root buoyancy, as well as causing rift-flank uplift. Permian rifting is well-established in the adjacent Lambert Rift, and was followed by Cretaceous strike-slip faulting and transtension associated with Gondwana break-up; this phase may have provided a more recent tectonic trigger for the initial uplift of the modern GSM. The Cretaceous rift-flank uplift model for the Gamburtsevs is appealing because it relates the initiation of intraplate mountain-building to large-scale geodynamic processes that led to the separation of Greater India from East Antarctica. It is also consistent with several geological and geophysical interpretations within the Lambert Rift. However, recent detrital thermochrology results from Oligocene-Quaternary sediments in Prydz Bay (Tochlin et al., 2012, G3) argue against the requirement for major Cretaceous rift

  7. Global Catalogue of the Martian Valley Networks: Evidences for Fluvial, Sapping and Subglacial Processes on Early Mars (United States)

    Grau Galofre, A.; Jellinek, A. M.


    We use erosion models and statistical morphometry schemes to show quantitative evidence for fluvial, glacial, groundwater sapping and subglacial erosion on the Noachian highlands, to then build a global map of valley network origin and distribution.

  8. adequacy of drainage channels f drainage channels in a small

    African Journals Online (AJOL)


    analysis, construction and maintenance of drainage c. Keywords: Keywords: Time of concentration, ... nwamba of Civil Engineering Department, University of Nigeria Nsuk. F DRAINAGE CHANNELS IN A SMALL URBAN .... The assessment of extreme precipitation is an important problem in hydrologic risk analysis and.

  9. Evolution of supraglacial brittle and ductile structures and drainage systems at a partly debris-covered alpine valley glacier during a 15 yr period (United States)

    Kellerer-Pirklbauer, Andreas; Kulmer, Bernd


    Based on five glacier stages (1998, 2003, 2006, 2009 and 2012) covering a period of 15 years, supraglacial crevasses and other structures as well as the drainage system at the tongue of Pasterze Glacier were mapped and interpreted. Pasterze Glacier is the largest glacier (c.16.5 km2) of the entire Eastern European Alps located in the Hohe Tauern Range, Central Austria at 47°05'N and 12°43'E. The glacier is in a stage of rapid recession and downwasting. The tongue is connected with the firn area by a mighty ice fall. 75% of the c.4.5 km long glacier tongue is covered by a supraglacial debris cover affecting glacier surface morphology related to differential ablation influencing the glacier's stress and strain field. High resolution orthoimagery and digital elevation models/DEM (both data sets with 20-50 cm grid resolution) were analysed. A structure glaciological mapping key was applied to discern relevant brittle (normal faults, thrust faults, strike-slip faults commonly associated with and en èchelon structures, and ice disintegration expressed as normal faults) and ductile structures (band ogives). Additionally, a geometric mapping key was used differentiating between chevron, splaying, transverse, and longitudinal crevasses as well as complex crevasse fields related to ice disintegration (commonly circular and semi-circular collapse features). The drainage system was mapped differentiating between supraglacial channels and moulins. Observations made during annual glacier measurement campaigns were additionally considered. Results indicate that the lower half of the glacier tongue was characterised during the observation period by ice disintegration (with semi-circular collapse features since 2003 near the glacier terminus and since 2009 in the central part) and thrust faults with downslope convexity (steady upslope migration of first occurrence during the observation period). In general, the crevasse density increased towards the left (NE), less debris

  10. Characterization of limestone reacted with acid-mine drainage in a pulsed limestone bed treatment system at the Friendship Hill National Historical Site, Pennsylvania, USA (United States)

    Hammarstrom, J.M.; Sibrell, P.L.; Belkin, H.E.


    Armoring of limestone is a common cause of failure in limestone-based acid-mine drainage (AMD) treatment systems. Limestone is the least expensive material available for acid neutralization, but is not typically recommended for highly acidic, Fe-rich waters due to armoring with Fe(III) oxyhydroxide coatings. A new AMD treatment technology that uses CO2 in a pulsed limestone bed reactor minimizes armor formation and enhances limestone reaction with AMD. Limestone was characterized before and after treatment with constant flow and with the new pulsed limestone bed process using AMD from an inactive coal mine in Pennsylvania (pH = 2.9, Fe = 150 mg/l, acidity = 1000 mg/l CaCO3). In constant flow experiments, limestone is completely armored with reddish-colored ochre within 48 h of contact in a fluidized bed reactor. Effluent pH initially increased from the inflow pH of 2.9 to over 7, but then decreased to 6 during operation. Limestone removed from a pulsed bed pilot plant is a mixture of unarmored, rounded and etched limestone grains and partially armored limestone and refractory mineral grains (dolomite, pyrite). The ???30% of the residual grains in the pulsed flow reactor that are armored have thicker (50- to 100-??m), more aluminous coatings and lack the gypsum rind that develops in the constant flow experiment. Aluminium-rich zones developed in the interior parts of armor rims in both the constant flow and pulsed limestone bed experiments in response to pH changes at the solid/solution interface. ?? 2003 Elsevier Ltd. All rights reserved.

  11. Development of a novel CsA-PLGA drug delivery system based on a glaucoma drainage device for the prevention of postoperative fibrosis. (United States)

    Dai, Zhaoxing; Yu, Xiaobo; Hong, Jiaxu; Liu, Xi; Sun, Jianguo; Sun, Xinghuai


    The formation of a scar after glaucoma surgery often leads to unsuccessful control of intraocular pressure, and should be prevented by using a variety of methods. We designed and developed a novel drug delivery system (DDS) comprising cyclosporine A (CsA) and poly(lactic-co-glycolic acid) (PLGA) based on a glaucoma drainage device (GDD) that can continuously release CsA to prevent postoperative fibrosis following glaucoma surgery. The CsA@PLGA@GDD DDS was observed by field emission scanning electron microscopy and revealed an asymmetric pore structure. Thermogravimetric analysis was performed to measure the weight loss and evaluate the thermal stability of the CsA@PLGA@GDD DDS. The in vitro drug release profile of the DDS was studied using high performance liquid chromatography, which confirmed that the DDS released CsA at a stable rate and maintained adequate CsA concentrations for a relatively long time. The biocompatibility of the DDS and the inhibitory effects on the postoperative fibrosis were investigated in vitro using rabbit Tenon's fibroblasts. The in vivo safety and efficacy of the DDS were examined by implanting the DDS into Tenon's capsules in New Zealand rabbits. Bleb morphology, intraocular pressure, anterior chamber reactions, and anterior chamber angiography were studied at a series of set times. The DDS kept the filtration pathway unblocked for a longer time compared with the control GDD. The results indicate that the CsA@PLGA@GDD DDS represents a safe and effective strategy for preventing scar formation after glaucoma surgery. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Drainage hydraulics of permeable friction courses (United States)

    Charbeneau, Randall J.; Barrett, Michael E.


    This paper describes solutions to the hydraulic equations that govern flow in permeable friction courses (PFC). PFC is a layer of porous asphalt approximately 50 mm thick that is placed as an overlay on top of an existing conventional concrete or asphalt road surface to help control splash and hydroplaning, reduce noise, and enhance quality of storm water runoff. The primary objective of this manuscript is to present an analytical system of equations that can be used in design and analysis of PFC systems. The primary assumptions used in this analysis are that the flow can be modeled as one-dimensional, steady state Darcy-type flow and that slopes are sufficiently small so that the Dupuit-Forchheimer assumptions apply. Solutions are derived for cases where storm water drainage is confined to the PFC bed and for conditions where the PFC drainage capacity is exceeded and ponded sheet flow occurs across the pavement surface. The mathematical solutions provide the drainage characteristics (depth and residence time) as a function of rainfall intensity, PFC hydraulic conductivity, pavement slope, and maximum drainage path length.

  13. Review of species of the Astyanax bimaculatus "caudal peduncle spot" subgroup sensu Garutti & Langeani (Characiformes, Characidae) from the rio La Plata and rio São Francisco drainages and coastal systems of southern Brazil and Uruguay. (United States)

    Lucena, Carlos Alberto S De; Soares, Helena Gouvea


    The species of the Astyanax bimaculatus 'caudal peduncle spot' subgroup of the drainages of the rios La Plata and São Francisco, as well as southeastern coastal systems of Brazil and Uruguay, are revised. Two nominal species are considered valid and are redescribed: Astyanax lacustris and A. abramis. Astyanax jacuhiensis, A. asuncionensis and A. altiparanae are recognized as new junior synonyms of A. lacustris. Bertoniolus paraguayensisis recognized as a new junior synonym of A. abramis. The names Astyanax orbignyanus, A. vittatus, and A. borealis are considered species inquirendae. Notes on A. maculisquamis, included in the 'caudal peduncle spot' subgroup from rio Guaporé (rio Madeira drainage), and Astyanax bahiensis from Bahia, mistakenly considered of the same subgroup, are presented.

  14. Effectiveness of closed suction drainage tip culture in hip arthroplasty. (United States)

    Park, Jai Hyung; Shon, Hyun Chul; Kim, Ji Wan; Park, Se Jin; Ko, Taeg Su; Park, Jong Hyon


    The aim of the present study was to investigate the correlation between bacterial growth in closed suction drainage tip culture and periprosthetic joint infection (PJI). Retrospective review included 256 patients who had undergone hip arthroplasty in which the closed suction drainage tip was cultured. Follow-up periods were longer than a year. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated in order to determine the significance of closed suction drainage tip culture in early diagnosis of infection. Patients with positive culture test were monitored to determine the effect of change in antibiotics on treatment of early infection. Eight of the 13 infections showed positive results from closed suction drainage tip culture. Eleven of the 243 non-infectious cases showed positive results after closed suction drainage tip culture (psuction drainage tip culture was 61.5%, with a specificity of 95.5%. Positive and negative predictive values were 42.1% and 97.9%, respectively. Systemic antibiotics were administered according to in vitro sensitivity of bacteria cultured from closed suction drainage tip in 13 of 19 positive culture cases. No statistically significant difference in infection risk was observed between the antibiotics group and the group to which antibiotics were not administered (p=0.51). Closed suction drainage tip culture can aid in the early detection of infection.

  15. Aerobic and Anaerobic Thiosulfate Oxidation by a Cold-Adapted, Subglacial Chemoautotroph (United States)

    Harrold, Zoë R.; Skidmore, Mark L.; Hamilton, Trinity L.; Desch, Libby; Amada, Kirina; van Gelder, Will; Glover, Kevin; Roden, Eric E.


    Geochemical data indicate that protons released during pyrite (FeS2) oxidation are important drivers of mineral weathering in oxic and anoxic zones of many aquatic environments, including those beneath glaciers. Oxidation of FeS2 under oxic, circumneutral conditions proceeds through the metastable intermediate thiosulfate (S2O32−), which represents an electron donor capable of supporting microbial metabolism. Subglacial meltwaters sampled from Robertson Glacier (RG), Canada, over a seasonal melt cycle revealed concentrations of S2O32− that were typically below the limit of detection, despite the presence of available pyrite and concentrations of the FeS2 oxidation product sulfate (SO42−) several orders of magnitude higher than those of S2O32−. Here we report on the physiological and genomic characterization of the chemolithoautotrophic facultative anaerobe Thiobacillus sp. strain RG5 isolated from the subglacial environment at RG. The RG5 genome encodes genes involved with pathways for the complete oxidation of S2O32−, CO2 fixation, and aerobic and anaerobic respiration with nitrite or nitrate. Growth experiments indicated that the energy required to synthesize a cell under oxygen- or nitrate-reducing conditions with S2O32− as the electron donor was lower at 5.1°C than 14.4°C, indicating that this organism is cold adapted. RG sediment-associated transcripts of soxB, which encodes a component of the S2O32−-oxidizing complex, were closely affiliated with soxB from RG5. Collectively, these results suggest an active sulfur cycle in the subglacial environment at RG mediated in part by populations closely affiliated with RG5. The consumption of S2O32− by RG5-like populations may accelerate abiotic FeS2 oxidation, thereby enhancing mineral weathering in the subglacial environment. PMID:26712544

  16. Widespread surface meltwater drainage in Antarctica (United States)

    Kingslake, J.; Ely, J.; Das, I.; Bell, R. E.


    Surface meltwater is thought to cause ice-shelf disintegration, which accelerates the contribution of ice sheets to sea-level rise. Antarctic surface melting is predicted to increase and trigger further ice-shelf disintegration during this century. These climate-change impacts could be modulated by an active hydrological network analogous to the one in operation in Greenland. Despite some observations of Antarctic surface and sub-surface hydrological systems, large-scale active surface drainage in Antarctica has rarely been studied. We use satellite imagery and aerial photography to reveal widespread active hydrology on the surface of the Antarctic Ice Sheet as far south as 85o and as high as 1800 m a.s.l., often near mountain peaks that protrude through the ice (nunataks) and relatively low-albedo `blue-ice areas'. Despite predominantly sub-zero regional air temperatures, as simulated by a regional climate model, Antarctic active drainage has persisted for decades, transporting water through surface streams and feeding vast melt ponds up to 80 km long. Drainage networks (the largest are over 100 km in length) form on flat ice shelves, steep outlet glaciers and ice-sheet flanks across the West and East Antarctica Ice Sheets. Motivated by the proximity of many drainage systems to low-albedo rock and blue-ice areas, we hypothesize a positive feedback between exposed-rock extent, BIA formation, melting and ice-sheet thinning. This feedback relies on drainage moving water long distances from areas near exposed rock, across the grounding line onto and across ice shelves - a process we observe, but had previously thought to be unlikely in Antarctica. This work highlights previously-overlooked processes, not captured by current regional-scale models, which may accelerate the retreat of the Antarctic Ice Sheet.

  17. Emprego de coberturas secas no controle da drenagem ácida de mina: estudos em campo Use of dry cover systems to control acid mine drainage: field studies

    Directory of Open Access Journals (Sweden)

    Sérgio Luciano Galatto


    Full Text Available No sul catarinense, cristais de pirita associados a rejeitos de beneficiamento de carvão mineral, quando alterados, desencadeiam o processo conhecido como drenagem ácida de mina (DAM. Este trabalho objetivou avaliar a eficiência de três sistemas de coberturas secas sobre estes rejeitos, como uma opção para o controle da DAM. Agentes neutralizantes da DAM como a cinza pesada e o calcário foram misturados com os rejeitos ou dispostos acima destes. Para reduzir a infiltração de água e difusão de oxigênio no meio, foi empregada uma camada de 50 cm de solo silte-argiloso compactado. Os experimentos foram monitorados por um ano, sendo analisados nos lixiviados alguns parâmetros indicadores da DAM, além da presença de bactérias ferro-oxidantes e sulfato-redutoras. Os resultados obtidos indicaram uma boa eficiência na prevenção da DAM de dois dos três sistemas de coberturas pesquisados.In the southern of the Santa Catarina state, the weathering and oxidation of pyrite-containing coal has been the major agent of Acid Mine Drainage (AMD production. The purpose of this study was to verify the efficiency of three different cover systems to inhibit AMD. Experiments were built in field lysimeters with alkaline agents - bottom ash and limestone - placed over or mixed with fresh coal waste. To reduce the water infiltration rates and oxygen diffusion 50 cm of compact mud soil layer was put over waste. The top cover was constituted by 10 cm of the same soil, mixed with bottom ash. During one year, these experiments have been monitored through chemical (pH, Eh, Fe2+, Fe total, Al, Ca, Mg, Zn, Pb and Mn and microbiological (Thiobacilus ferroxidans presence composition of effluents. The results indicated that two of three cover systems employed were efficient on AMD prevention.

  18. Subglacial discharges create fluctuating foraging hotspots for sea birds in tidewater glacier bays (United States)

    Urbanski, Jacek Andrzej; Stempniewicz, Lech; Węsławski, Jan Marcin; Dragańska-Deja, Katarzyna; Wochna, Agnieszka; Goc, Michał; Iliszko, Lech


    Although the processes occurring at the front of an ice face in tidewater glacier bays still await thorough investigation, their importance to the rapidly changing polar environment is spurring a considerable research effort. Glacier melting, sediment delivery and the formation of seabird foraging hotspots are governed by subglacial discharges of meltwater. We have combined the results of tracking black-legged kittiwakes Rissa tridactyla equipped with GPS loggers, analyses of satellite images and in situ measurements of water temperature, salinity and turbidity in order to examine the magnitude and variability of such hotspots in the context of glacier bay hydrology. Small though these hotspots are in size, foraging in them appears to be highly intensive. They come into existence only if the subglacial discharge reaches the surface, if the entrainment velocity at a conduit is high and if there is sufficient macroplankton in the entrainment layer. The position and type of subglacial discharges may fluctuate in time and space, thereby influencing glacier bay hydrology and the occurrence of foraging hotspots. PMID:28266602

  19. Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland (United States)

    Jordan, Thomas M.; Cooper, Michael A.; Schroeder, Dustin M.; Williams, Christopher N.; Paden, John D.; Siegert, Martin J.; Bamber, Jonathan L.


    Subglacial roughness can be determined at a variety of length scales from radio-echo sounding (RES) data either via statistical analysis of topography or inferred from basal radar scattering. Past studies have demonstrated that subglacial terrain exhibits self-affine (power law) roughness scaling behaviour, but existing radar scattering models do not take this into account. Here, using RES data from northern Greenland, we introduce a self-affine statistical framework that enables a consistent integration of topographic-scale roughness with the electromagnetic theory of radar scattering. We demonstrate that the degree of radar scattering, quantified using the waveform abruptness (pulse peakiness), is topographically controlled by the Hurst (roughness power law) exponent. Notably, specular bed reflections are associated with a lower Hurst exponent, with diffuse scattering associated with a higher Hurst exponent. Abrupt waveforms (specular reflections) have previously been used as a RES diagnostic for basal water, and to test this assumption we compare our radar scattering map with a recent prediction for the basal thermal state. We demonstrate that the majority of thawed regions (above pressure melting point) exhibit a diffuse scattering signature, which is in contradiction to the prior approach. Self-affine statistics provide a generalised model for subglacial terrain and can improve our understanding of the relationship between basal properties and ice-sheet dynamics.

  20. Preliminary Analysis of Life within a Former Subglacial Lake Sediment in Antarctica

    Directory of Open Access Journals (Sweden)

    Gavin Burns


    Full Text Available Since the first descriptions of Antarctic subglacial lakes, there has been a growing interest and awareness of the possibility that life will exist and potentially thrive in these unique and little known environments. The unusual combination of selection pressures, and isolation from the rest of the biosphere, might have led to novel adaptations and physiology not seen before, or indeed to the potential discovery of relic populations that may have become extinct elsewhere. Here we report the first microbiological analysis of a sample taken from a former subglacial lake sediment in Antarctica (Lake Hodgson, on the Antarctic Peninsula. This is one of a number of subglacial lakes just emerging at the margins of the Antarctic ice sheet due to the renewed onset of deglaciation. Microbial diversity was divided into 23.8% Actinobacteria, 21.6% Proteobacteria, 20.2% Planctomycetes and 11.6% Chloroflexi, characteristic of a range of habitat types ( Overall, common sequences were neither distinctly polar, low temperature, freshwater nor marine. Twenty three percent of this diversity could only be identified to “unidentified bacterium”. Clearly these are diverse ecosystems with enormous potential.

  1. Subglacial discharges create fluctuating foraging hotspots for sea birds in tidewater glacier bays (United States)

    Urbanski, Jacek Andrzej; Stempniewicz, Lech; Węsławski, Jan Marcin; Dragańska-Deja, Katarzyna; Wochna, Agnieszka; Goc, Michał; Iliszko, Lech


    Although the processes occurring at the front of an ice face in tidewater glacier bays still await thorough investigation, their importance to the rapidly changing polar environment is spurring a considerable research effort. Glacier melting, sediment delivery and the formation of seabird foraging hotspots are governed by subglacial discharges of meltwater. We have combined the results of tracking black-legged kittiwakes Rissa tridactyla equipped with GPS loggers, analyses of satellite images and in situ measurements of water temperature, salinity and turbidity in order to examine the magnitude and variability of such hotspots in the context of glacier bay hydrology. Small though these hotspots are in size, foraging in them appears to be highly intensive. They come into existence only if the subglacial discharge reaches the surface, if the entrainment velocity at a conduit is high and if there is sufficient macroplankton in the entrainment layer. The position and type of subglacial discharges may fluctuate in time and space, thereby influencing glacier bay hydrology and the occurrence of foraging hotspots.

  2. Potential Activity of Subglacial Microbiota Transported to Anoxic River Delta Sediments

    DEFF Research Database (Denmark)

    Cameron, Karen A.; Stibal, Marek; Olsen, Nikoline S.


    The Watson River drains a portion of the SW Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers...... shift in predominant community members and a decline in diversity and cell abundance. These results highlight the need for further investigations into the fate of subglacial microbiota within downstream environments.......The Watson River drains a portion of the SW Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers...... of sediments within the river delta. A long-term (12-month) incubation experiment was established using Watson River delta sediment under anaerobic conditions, with and without CO2/H2 enrichment. Within CO2/H2-amended incubations, sulphate depletion and a shift in the microbial community to a 52% predominance...

  3. Closed suction drainage versus closed simple drainage in the management of modified radical mastectomy wounds. (United States)

    Ezeome, E R; Adebamowo, C A


    To compare the outcomes of modified radical mastectomy wounds managed by closed wound drainage with suction and without suction. A prospective randomised trial was conducted at the University College Hospital in Ibadan, and the University of Nigeria Teaching Hospital in Enugu. Fifty women who required modified radical mastectomy for breast cancer were randomised to have closed wound drainage with suction (26 patients) and closed wound drainage without suction (24 patients). There was no significant difference in the intraoperative and postoperative variables. Suction drainage drained less volume of fluid and stayed for a shorter time in the wound, but the differences were not significant. There was no difference in the length of hospital stay, time to stitch removal, and number of dressing changes. More haematomas and wound infections occurred in the simple drain group while more seromas occurred in the suction drain group, but these were not significant. The suction drain was more difficult to manage and the cost was 15 times higher than the simple drainage system. Closed simple drains are not inferior to suction drains in mastectomy wounds and, considering the cost saving and simplicity of postoperative care, they are preferable to suction drains.

  4. Drainage identification analysis and mapping, phase 2 : technical brief. (United States)


    This research studied, tested and rectified the compatibility issue related to the recent upgrades of : NJDOT vendor inspection software, and uploaded all collected data to make Drainage Identification : Analysis and Mapping System (DIAMS) current an...

  5. Response of a landfill drainage pipe buried in a trench

    National Research Council Canada - National Science Library

    Brachman, R W; Krushelnitzky, R P


    The structural response of drainage pipes used in landfill leachate collection systems depends on the properties of both the pipe and the backfill soil, as well as the type of backfill configuration...

  6. Effects of Bedrock Lithology and Subglacial Till on the Motion of Ruth Glacier, Alaska, Deduced from Five Pulses from 1973-2012 (United States)

    Turrin, J.; Forster, R.; Sauber, Jeanne; Hall, Dorothy K.; Bruhn, R.


    A pulse is a type of unstable glacier flow intermediate between normal flow and surging. Using Landsat MSS, TM, and ETM+ imagery and feature tracking software, a time-series of mostly annual velocity maps from 1973 to 2012 was produced that reveals five pulses of Ruth Glacier, Alaska. Peaks in ice velocity were found in the 1981, 1989, 1997, 2003, and 2010; approximately every 7 years. During these peak years the ice velocity increased 300%, from approximately 40 m/yr to 160 m/yr, and occurred in an area of the glacier underlain by sedimentary bedrock. Based on the spatio-temporal behavior of Ruth Glacier during the pulse cycles, we suggest the pulses are due to enhanced basal motion via deformation of a subglacial till. The cyclical nature of the pulses is theorized to be due to a thin till, with low permeability, that causes incomplete drainage of the till between the pulses, followed by eventual recharge and dilation of the till. These findings suggest care is needed when attempting to correlate changes in regional climate with decadal-scale changes in velocity, because in some instances basal conditions may have a greater influence on ice dynamics than climate.

  7. Improved regional groundwater flow modeling using drainage features: a case study of the central northern karst aquifer system of Puerto Rico (USA) (United States)

    Ghasemizadeh, Reza; Yu, Xue; Butscher, Christoph; Padilla, Ingrid Y.; Alshawabkeh, Akram


    In northern Puerto Rico (USA), subsurface conduit networks with unknown characteristics, and surface features such as springs, rivers, lagoons and wetlands, drain the coastal karst aquifers. In this study, drain lines connecting sinkholes and springs are used to improve the developed regional model by simulating the drainage effects of conduit networks. Implemented in an equivalent porous media (EPM) approach, the model with drains is able to roughly reproduce the spring discharge hydrographs in response to rainfall. Hydraulic conductivities are found to be scale dependent and significantly increase with higher test radius, indicating scale dependency of the EPM approach. Similar to other karst regions in the world, hydraulic gradients are steeper where the transmissivity is lower approaching the coastline. This study enhances current understanding of the complex flow patterns in karst aquifers and suggests that using a drainage feature improves modeling results where available data on conduit characteristics are minimal.

  8. Implications of sediment transport by subglacial water flow for interpreting contemporary glacial erosion rates (United States)

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


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

  9. The importance of lymphatic drainage in physiotherapy


    VINKLEROVÁ, Miroslava


    The theoretical part summarizes all the theoretical knowledge on the topic. I am presenting a brief history of the discovery of the lymphatic vessels and the lymphatic drainage, the lymphatic system anatomy and its functions in the human body. Next, I have defined the concept of lymphoedema and divided it by its origin to primary and secondary lymphedema. The work includes the diagnosis of lymphedema , both conservative and surgical treatment options, indications and contraindications of lymp...

  10. A Novel Mediastinal Drainage Tube for Mediastinitis

    Directory of Open Access Journals (Sweden)

    Jun Ho Yhang


    Full Text Available Mediastinitis is a life-threatening disease, and effective drainage is needed to treat mediastinitis with abscess formation. We recommend an alternative drainage method using chest tube binding with a Silastic Penrose drainage tube. The use of a Silastic Penrose drainage tube may help to manage mediastinitis with abscess formation. This method facilitates effective draining and prevents tissue adhesion.


    Directory of Open Access Journals (Sweden)

    I. C. Stanga


    Full Text Available This article covers a monographic presentation of the soils from the Tutova drainage basin. The analysis of the pedogeographic assemblage was performed based on the soil surveys of the territories corresponding to Tutova’s drainage basin, and completed with field research. The taxonomic classification was done in accordance with the Romanian System of Soil Taxonomy (2003 and the soil map was created at a 1:25.000 scale. The zonal soils dominate the region; the Chernisols are on the first rank with a share of 39.95%, followed by Luvisols with a percent of 27.62%. Among the soils with an azonal and intrazonal character, the entic soils are dominant (21.90%, followed by Anthrosols (8.89% and by Hydrisols (1.64%.

  12. The Subglacial Access and Fast Ice Research Experiment (SAFIRE): 1. Borehole-based englacial and subglacial measurements from a rapidly-moving tidewater glacier: Store Glacier, Greenland (United States)

    Hubbard, Bryn; Doyle, Samuel; Christoffersen, Poul; Young, Tun Jan; Hofstede, Coen; Hubbard, Alun; Box, Jason; Todd, Joe; Bougamont, Marion


    As part of the Subglacial Access and Fast Ice Research Experiment (SAFIRE) pressurised hot water was used to drill four 603-616 m-long boreholes to the bed of the Greenland Ice Sheet at a site located 30 km from the calving front of fast-flowing, marine-terminating Store Glacier (70 degrees N, ~1000 m elevation). Four wired sensor strings were successfully installed in three of the boreholes. These included a thermistor string to obtain the englacial temperature profile installed in the same borehole as a string of tilt sensors to measure borehole deformation, and two sets of combined water pressure, electrical conductivity and turbidity sensors installed just above the bed in separate, adjacent boreholes. The boreholes made a strong hydrological connection to the bed during drilling, draining rapidly to ~80 m below the ice surface. The connection of subsequent boreholes was observed as a perturbation in water pressure and temperature recorded in neighbouring boreholes, indicating an effective hydrological connection between them. The sensors, which were wired to data-loggers at the surface, operated for between ~30 and >80 days from late summer into autumn before the cables stretched and snapped, with the lowermost sensors failing first. The records obtained from these sensors reveal (i) subglacial water pressures that were close to overburden but which generally increased through the period of measurement and varied diurnally by ~0.3 m, (ii) a minimum englacial temperature of -21 degrees C underlain by a zone of temperate ice, some tens of m thick, located immediately above the bed, and (iii) high rates of internal deformation and strain that increased towards the bed. These borehole observations are complemented by GPS measurements of ice motion, meteorological data, and seismic and radar surveys.

  13. Culturable bacteria in subglacial sediments and ice from two Southern Hemisphere glaciers. (United States)

    Foght, J; Aislabie, J; Turner, S; Brown, C E; Ryburn, J; Saul, D J; Lawson, W


    Viable prokaryotes have been detected in basal sediments beneath the few Northern Hemisphere glaciers that have been sampled for microbial communities. However, parallel studies have not previously been conducted in the Southern Hemisphere, and subglacial environments in general are a new and underexplored niche for microbes. Unfrozen subglacial sediments and overlying glacier ice samples collected aseptically from the Fox Glacier and Franz Josef Glacier in the Southern Alps of New Zealand now have been shown to harbor viable microbial populations. Total direct counts of 2-7 x 10(6) cells g(-1) dry weight sediment were observed, whereas culturable aerobic heterotrophs ranged from 6-9 x 10(5) colony-forming units g(-1) dry weight. Viable counts in the glacier ice typically were 3-4 orders of magnitude smaller than in sediment. Nitrate-reducing and ferric iron-reducing bacteria were detected in sediment samples from both glaciers, but were few or below detection limits in the ice samples. Nitrogen-fixing bacteria were detected only in the Fox Glacier sediment. Restriction fragment analysis of 16S rDNA amplified from 37 pure cultures of aerobic heterotrophs capable of growth at 4 degrees C yielded 23 distinct groups, of which 11 were identified as beta-Proteobacteria. 16S rDNA sequences from representatives of these 11 groups were analyzed phylogenetically and shown to cluster with bacteria such as Polaromonas vacuolata and Rhodoferax antarcticus, or with clones obtained from permanently cold environments. Chemical analysis of sediment and ice samples revealed a dilute environment for microbial life. Nevertheless, both the sediment samples and one ice sample demonstrated substantial aerobic mineralization of 14C-acetate at 8 degrees C, indicating that sufficient nutrients and viable psychrotolerant microbes were present to support metabolism. Unfrozen subglacial sediments may represent a significant global reservoir of biological activity with the potential to

  14. Geochemical distribution and removal of As, Fe, Mn and Al in a surface water system affected by acid mine drainage at a coalfield in Southwestern China (United States)

    Wu, Pan; Tang, Changyuan; Liu, Congqiang; Zhu, Lijun; Pei, Tingquan; Feng, Lijuan


    The chemical characteristics, formation and natural attenuation of pollutants in the coal acid mine drainage (AMD) at Xingren coalfield, Southwest China, are discussed in this paper based on the results of a geochemical investigation as well as geological and hydrogeological background information. The chemical composition of the AMD is controlled by the dissolution of sulfide minerals in the coal seam, the initial composition of the groundwater and the water-rock interaction. The AMD is characterized by high sulfate concentrations, high levels of dissolved metals (Fe, Al, Mn, etc.) and low pH values. Ca2+ and SO4 2- are the dominant cation and anion in the AMD, respectively, while Ca2+ and HCO3 - are present at significant levels in background water and surface water after the drainage leaves the mine site. The pH and alkalinity increase asymptotically with the distance along the flow path, while concentrations of sulfate, ferrous iron, aluminum and manganese are typically controlled by the deposition of secondary minerals. Low concentrations of As and other pollutants in the surface waters of the Xingren coalfield could be due to relatively low quantities being released from coal seams, to adsorption and coprecipitation on secondary minerals in stream sediments, and to dilution by unpolluted surface recharge. Although As is not the most serious water quality problem in the Xingren region at present, it is still a potential environmental problem.

  15. Application of BIM Technology in Building Water Supply and Drainage Design (United States)

    Wei, Tianyun; Chen, Guiqing; Wang, Junde


    Through the application of BIM technology, the idea of building water supply and drainage designers can be related to the model, the various influencing factors to affect water supply and drainage design can be considered more comprehensively. BIM(Building information model) technology assist in improving the design process of building water supply and drainage, promoting the building water supply and drainage planning, enriching the building water supply and drainage design method, improving the water supply and drainage system design level and building quality. Combined with fuzzy comprehensive evaluation method to analyze the advantages of BIM technology in building water supply and drainage design. Therefore, application prospects of BIM technology are very worthy of promotion.

  16. Subglacial conditions and Scandinavian Ice Sheet dynamics at the coarse-grained substratum of the fore-mountain area of southern Poland (United States)

    Salamon, Tomasz


    The fore-mountain areas of southern Poland are locally composed of the coarse-grained sediments of alluvial fans, which created unusual conditions under the advancing Scandinavian Ice Sheet during the Elsterian glaciation. This highly permeable substratum potentially enabled rapid outflow of meltwater from the ice sheet base, thereby reducing the water pressure and strongly influencing the ice sheet dynamics. The subglacial conditions and the relationship between the ice sheet behaviour and its coarse-grained substratum were studied at the foreland of the western Carpathian Mountains. The sedimentological and structural analysis of the till and related sediments that were deposited above the alluvial gravel of the fore-mountain fans are presented. The study indicates that despite the high permeability of the coarse-grained substratum, it did not slow the ice sheet movement. Conversely, the ice sheet moved mainly due to basal slip and locally shallow deformations. This was a consequence of very high basal water pressure, which resulted largely from the presence of permafrost that restricted subglacial groundwater outflow. In addition, the ice sheet substratum was inclined opposite to the direction of its movement, increasing the pressure of the subglacial water. Numerous subhorizontal sandy laminae within the till indicate that the meltwater from the ice sheet base was drained by a water film along the ice/bed interface. The water escape structures within the till and subtill sediments indicate the occasional instability of the ice sheet hydrological system and suggest that the meltwater was periodically stored in the ice sheet base. Temporal changes occurring in the ice sheet hydrological system might indicate variations in the ice sheet behaviour; i.e. phases of relatively fast ice flow and phases of ice stagnation. The latter were probably correlated with the freezing of the ice margin to its base. The study shows how the coarse-grained substratum could

  17. Drainage and Stratification Kinetics of Foam Films (United States)

    Zhang, Yiran; Sharma, Vivek


    Baking bread, brewing cappuccino, pouring beer, washing dishes, shaving, shampooing, whipping eggs and blowing bubbles all involve creation of aqueous foam films. Foam lifetime, drainage kinetics and stability are strongly influenced by surfactant type (ionic vs non-ionic), and added proteins, particles or polymers modify typical responses. The rate at which fluid drains out from a foam film, i.e. drainage kinetics, is determined in the last stages primarily by molecular interactions and capillarity. Interestingly, for certain low molecular weight surfactants, colloids and polyelectrolyte-surfactant mixtures, a layered ordering of molecules, micelles or particles inside the foam films leads to a stepwise thinning phenomena called stratification. Though stratification is observed in many confined systems including foam films containing particles or polyelectrolytes, films containing globular proteins seem not to show this behavior. Using a Scheludko-type cell, we experimentally study the drainage and stratification kinetics of horizontal foam films formed by protein-surfactant mixtures, and carefully determine how the presence of proteins influences the hydrodynamics and thermodynamics of foam films.

  18. The Impact of Drainage Reorganization on Cenozoic Topography (United States)

    Yanites, B. J.; Ehlers, T. A.


    Landscape evolution and the resulting sedimentary deposits are controlled by the development and organization of drainage basins. As a landscape evolves within a climatic and tectonic environment, drainage reorganization events can occur, where one river basin grows at the expense of another. The added discharge downstream of a river capture location will generate a transient topographic response. The records of these events are preserved the sedimentary record and modern topography. Drainage reorganization has been proposed to occur in a number of major drainage systems around the world including the Colorado, Rhine, Snake, Yellow, Yangtze, Indus, and Zambezi rivers as well as a number of smaller rivers. Yet little work has focused on quantifying the topographic and erosional consequence of such events. Here we propose a simple model that quantifies the impacts of drainage capture on the evolution of a drainage basin. The model is based on the inverse slope-contributing drainage area relationship observed in rivers throughout the world and describes the expected river elevation change as drainage area is added (and therefore slopes lowered) by a capture event. Furthermore, we develop a numerical model of drainage capture that quantifies the transience of erosion and sediment production based on a shear stress dependent fluvial incision and sediment transport model. Our focus here is on quantifying the impact of capture of the Rhine/Aare river system (~45,000 km2) during the late Pliocene/early Pleistocene. Our models suggest 500-800 m of river elevation change (lowering profiles) occurred over short time periods (less than a million years), contributing as much as 0.4 mm/yr of erosion to the Alpine foreland and Swiss Alps when averaged over the last few million years. The predicted incision magnitudes are consistent with incision measured from the elevation of Pliocene and early Pleistocene river gravels, suggesting that the majority of incision across northern

  19. Guidelines to Avoid Biocontamination of Antarctic Subglacial Aquatic Environments: Forward Contamination Concerns, Environmental Management and Scientific Stewardship of Icy analogue environments (United States)

    Race, M. S.; Hobbie, J.; et al.


    For more than a decade, scientists and space mission planners have recognized the importance of collaborative information exchange with the Antarctic research community to address their many shared exploration challenges, from drilling methods, remote sample collection, and data interpretation, to concerns about cross contamination that could adversely impact both the environment and interpretation of scientific data. Another shared concern exists in the regulatory realm; both the Antarctic and outer space environments are subject to separate international treaties that impose regulatory controls and oversight with serious implications for exploration planning. In recent years, both communities have faced the need to adjust their regulatory controls in light of fast-paced advances in scientific understanding of extreme environments, particularly related to potential microbial life. Both communities have sought and received advice from the National Research Council (NRC) through studies that suggested ways to update their respective oversight and regulatory systems while allowing for continued scientific exploration. A recently completed NRC study "Exploration of Antarctic Subglacial Aquatic Environments: Environmental and Scientific Stewardship" provided a suite of recommendations to address1) 'cleanliness' levels necessary for equipment and devices used in exploration of subglacial aquatic environments, as well as 2) the scientific basis for contamination standards, and 3) the steps for defining an overall exploration strategy conducive to sound environmental management and scientific stewardship. This talk will present the findings of the recent multinational NRC study, which is likely to translate into useful information for analogue studies that proceed to test techniques and capabilities for exploring an Europan ocean, other icy celestial locations, and related science targets on Earth. As the science and exploration of subglacial environments grows beyond its

  20. Closed suction drainage versus closed simple drainage in the ...

    African Journals Online (AJOL)

    Objective: To compare the outcome of modified radical mastectomy wounds managed by closed wound drainage with suction and without suction. Methods: A prospective randomized trial was conducted at the University College Hospital Ibadan and University of Nigeria Teaching Hospital Enugu, Nigeria. Fifty women who ...

  1. In-Situ Observations of a Subglacial Outflow Plume in a Greenland Fjord (United States)

    Mankoff, K. D.; Straneo, F.; Singh, H.; Das, S. B.


    We present oceanographic observations collected in and immediately outside of a buoyant, fresh, sediment-laden subglacial outflow plume rising up the marine-terminating front of Sarqardleq Glacier, Greenland (68.9 N, 50.4 W). Subglacial outflow plumes, associated with the discharge at depth of upstream glacial surface melt, entrain the relatively warm fjord waters and are correlated with enhanced submarine melt and increased calving. Few in-situ observations exist due to the challenges of making measurements at the calving front of glaciers. Our data were collected using a small boat, a helicopter, and a JetYak (a remote-controlled jet-ski-powered kayak). Temperature and salinity profiles in, around, and far from the plume are used to described its oceanographic properties, spatial extent, and temporal variability. This plume rises vertically up the ice front expanding laterally and away from the ice, over-shoots its stable isopycnal and reaches the surface. Its surface expression is identified by colder, saltier, sediment-laden water flowing at ~5 m/s away from the ice face. Within ~300 m from the ice it submerges as it seeks buoyant stability.

  2. A cost comparison of traditional drainage and SUDS in Scotland. (United States)

    Duffy, A; Jefferies, C; Waddell, G; Shanks, G; Blackwood, D; Watkins, A


    The Dunfermline Eastern Expansion (DEX) is a 350 ha mixed development which commenced in 1996. Downstream water quality and flooding issues necessitated a holistic approach to drainage planning and the site has become a European showcase for the application of Sustainable Urban Drainage Systems (SUDS). However, there is minimal data available regarding the real costs of operating and maintaining SUDS to ensure they continue to perform as per their design function. This remains one of the primary barriers to the uptake and adoption of SUDS. This paper reports on what is understood to be the only study in the UK where actual costs of constructing and maintaining SUDS have been compared to an equivalent traditional drainage solution. To compare SUDS costs with traditional drainage, capital and maintenance costs of underground storage chambers of analogous storage volumes were estimated. A whole life costing methodology was then applied to data gathered. The main objective was to produce a reliable and robust cost comparison between SUDS and traditional drainage. The cost analysis is supportive of SUDS and indicates that well designed and maintained SUDS are more cost effective to construct, and cost less to maintain than traditional drainage solutions which are unable to meet the environmental requirements of current legislation. (c) IWA Publishing 2008.

  3. Pre-operative biliary drainage for obstructive jaundice (United States)

    Fang, Yuan; Gurusamy, Kurinchi Selvan; Wang, Qin; Davidson, Brian R; Lin, He; Xie, Xiaodong; Wang, Chaohua


    Background Patients with obstructive jaundice have various pathophysiological changes that affect the liver, kidney, heart, and the immune system. There is considerable controversy as to whether temporary relief of biliary obstruction prior to major definitive surgery (pre-operative biliary drainage) is of any benefit to the patient. Objectives To assess the benefits and harms of pre-operative biliary drainage versus no pre-operative biliary drainage (direct surgery) in patients with obstructive jaundice (irrespective of a benign or malignant cause). Search methods We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Central Register of Controlled Clinical Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until February 2012. Selection criteria We included all randomised clinical trials comparing biliary drainage followed by surgery versus direct surgery, performed for obstructive jaundice, irrespective of the sample size, language, and publication status. Data collection and analysis Two authors independently assessed trials for inclusion and extracted data. We calculated the risk ratio (RR), rate ratio (RaR), or mean difference (MD) with 95% confidence intervals (CI) based on the available patient analyses. We assessed the risk of bias (systematic overestimation of benefit or systematic underestimation of harm) with components of the Cochrane risk of bias tool. We assessed the risk of play of chance (random errors) with trial sequential analysis. Main results We included six trials with 520 patients comparing pre-operative biliary drainage (265 patients) versus no pre-operative biliary drainage (255 patients). Four trials used percutaneous transhepatic biliary drainage and two trials used endoscopic sphincterotomy and stenting as the method of pre-operative biliary drainage. The risk of bias was high in all trials. The proportion of patients with malignant obstruction varied between 60

  4. An In-Situ Deep-UV Optical Probe for Examining Biochemical Presence in Deep Glaciers and Sub-Glacial Lakes (United States)

    Lane, A. L.; Behar, A.; Bhartia, R.; Conrad, P. G.; Hug, W. F.


    The quest to study and understand extremophiles has led to many quite different research paths in the past 30 years. One of the more difficult directions has been the study of biochemical material in deep glacial ice and in subglacial lakes. Lake Vostok in Eastern Antarctica has been perhaps the most discussed subglacial lake because of its large size (~14,000 sq km), deep location under >3700 m of overlying ice, and thick sediment bed (~200m). Once the physical conditions of the Lake were assessed, questions immediately arose about the potential existence of biological material - either extinct or possibly extant under conditions of extremely limited energy and nutrients [1-2]. To investigate the biology of Vostok, via in-situ methods, is a major issue that awaits proven techniques that will not contaminate the Lake beyond what may have occurred to date. Lake Ellsworth, in West Antarctica, also discovered by ice penetrating radar, is of significantly smaller size, but is also >3500 m below the overlying ice. It represents a wonderful opportunity to design, engineer and build in-situ delivery systems that consider bio-cleanliness approaches to enable examination of its water, sediment bed and the "roof" area accretion ice for biochemicals [3]. Our laboratory has been developing deep UV fluorescence and UV Raman instrumentation to locate and classify organic material at a variety of extremophile locations. The confluence of the measurement techniques and the engineering for high external pressure instrument shells has enabled us to design and begin prototype fabrication of a biochemical sensing probe that can be inserted into a hot-water drilled ice borehole, functioning as a local area mapper in water environments as deep as 6000 m. Real-time command and control is conducted from a surface science station. We have been using the deep Vostok ice cores at the U.S. National Ice Core Lab to validate our science and data analysis approaches with an "inverted" system

  5. Microscale evidence of liquefaction and its potential triggers during soft-bed deformation within subglacial traction tills (United States)

    Phillips, Emrys R.; Evans, David J. A.; van der Meer, Jaap J. M.; Lee, Jonathan R.


    Published conceptual models argue that much of the forward motion of modern and ancient glaciers is accommodated by deformation of soft-sediments within the underlying bed. At a microscale this deformation results in the development of a range of ductile and brittle structures in water-saturated sediments as they accommodate the stresses being applied by the overriding glacier. Detailed micromorphological studies of subglacial traction tills reveal that these polydeformed sediments may also contain evidence of having undergone repeated phases of liquefaction followed by solid-state shear deformation. This spatially and temporally restricted liquefaction of subglacial traction tills lowers the shear strength of the sediment and promotes the formation of "transient mobile zones" within the bed, which accommodate the shear imposed by the overriding ice. This process of soft-bed sliding, alternating with bed deformation, facilitates glacier movement by way of 'stick-slip' events. The various controls on the slip events have previously been identified as: (i) the introduction of pressurised meltwater into the bed, a process limited by the porosity and permeability of the till; and (ii) pressurisation of porewater as a result of subglacial deformation; to which we include (iii) episodic liquefaction of water-saturated subglacial traction tills in response to glacier seismic activity (icequakes), which are increasingly being recognized as significant processes in modern glaciers and ice sheets. As liquefaction operates only in materials already at very low values of effective stress, its process-form signatures are likely indicative of glacier sub-marginal tills.

  6. Subglacial bed conditions during Late Pleistocene glaciations and their impact on ice dynamics in the southern North Sea

    NARCIS (Netherlands)

    Passchier, S.; Laban, C.; Mesdag, C.S.; Rijsdijk, K.F.


    Changes in subglacial bed conditions through multiple glaciations and their effect on ice dynamics are addressed through an analysis of glacigenic sequences in the Upper Pleistocene stratigraphy of the southern North Sea basin. During Elsterian (MIS 12) ice growth, till deposition was subdued when

  7. Definition of the drainage filter problem

    NARCIS (Netherlands)

    Zaslavsky, D.


    It is common to consider the following: I. Retention of soil particles that may enter the drainage pipe and cause its clogging. For some sensitive structures it is important to prevent settlements due to soil transportation by drainage water.

  8. Integrated urban drainage, status and perspectives

    DEFF Research Database (Denmark)

    Harremoës, Poul


    measures are local infiltration, source control, storage basins, local treatment and real time control. New paradigms have been introduced: risk of pollution due to system failure, technology for water reuse, sustainability, new architecture and greener up-stream solutions as opposed to down......This paper summarises the status of urban storm drainage as an integrated professional discipline, including the management-policy interface, by which the goals of society are implemented. The paper assesses the development of the discipline since the INTERURBA conference in 1992 and includes...

  9. Geomorphic signature of an Antarctic palaeo-ice stream: implications for understanding subglacial processes and grounding line retreat (United States)

    Livingstone, S. J.; Jamieson, S.; Vieli, A.; O'Cofaigh, C.; Stokes, C. R.; Hillenbrand, C.


    The ability to capture the complex spatial and temporal variability exhibited by ice streams in Antarctica and Greenland at short (decadal) time-scales, remains one of the key challenges in numerical modelling and underlies current uncertainties with predicting future contributions of ice sheets to sea-level rise. This has made ice streams a major focus for current glaciological research, particularly with regard to the processes occurring at the ice-bed interface. Such studies unfortunately, only provide a ‘snap-shot’ of the life-cycle of an ice stream, limited to the last few decades, and so there is a need for complementary investigations of former zones of fast flow in palaeo-ice sheets. The ability to observe directly the former beds of palaeo-ice streams has allowed important spatial and temporal information to be obtained on the processes that occurred at the ice-bed interface and on ice dynamics associated with the evolution of palaeo-ice streams. We present new glacial geomorphological evidence from a marine palaeo-ice stream in Marguerite Bay, Antarctic Peninsula (Ó Cofaigh et al. 2002, 2005). The landform assemblage of this palaeo-ice stream system has been derived from the mapping of over 16,000 glacial landforms from high-resolution multibeam swath-bathymetry and input into a GIS database. Analysis of the spatial distribution and geomorphic relationships between landforms and landform assemblages has revealed a complex basal régime, while the overall geomorphic imprint, constrained by radiocarbon dates, has been used to reconstruct the retreat style and history of the palaeo-ice stream. Mapping of relict subglacial meltwater channels has revealed an intricate hydrological system characterised by multiple network types (cf. Anderson & Oakes-Fretwell, 2008) that are strongly dependent on the underlying substrate and which show progressive organisation seaward. Grounding zone wedges (GZWs), formed by the subglacial transport and then deposition of

  10. The Subglacial Access and Fast Ice Research Experiment (SAFIRE): 3. Englacial and subglacial conditions revealed by seismic reflection data on Store Glacier, West Greenland. (United States)

    Hofstede, Coen; Eisen, Olaf; Young, Tun Jan; Doyle, Samuel; Hubbard, Bryn; Christoffersen, Poul; Hubbard, Alun


    Basal conditions have a profound influence on the dynamics of outlet glaciers. As part of the SAFIRE research programme, we carried out a seismic survey on Store Glacier, a tidewater glacier terminating in Uummanaq Fjord in West Greenland (see joint abstracts by Christoffersen et al. and Doyle et al. for details). At the survey site the ice moves 700m/a making the terrain crevassed and bumpy. Despite the rough terrain we collected two 1.5 km long survey lines parallel and perpendicular to the ice flow direction using a 300m snow streamer and explosives as a source. The seismic data reveal an ice thickness of about 620m and 20 to 30m of subglacial sediment on the upstream side of the area thinning in the downstream direction. From polarity reversals seen along the ice-bed contact we speculate that the sediments have varying degrees of water content. The ice itself has several englacial reflections parallel and close to the bed. At approximately 475m depth, a clear single englacial reflection is observed in the parallel survey line. Thermistor data installed at this location show a clear increase in ice temperature starting at this depth. We speculate that the observed englacial reflection is caused by a change in crystal orientation fabric allowing greater ice deformation below this depth causing increased strain heating.

  11. Influence of water chemistry on the distribution of an acidophilic protozoan in an acid mine drainage system at the abandoned Green Valley coal mine, Indiana, USA

    Energy Technology Data Exchange (ETDEWEB)

    Brake, S.S.; Dannelly, H.K.; Connors, K.A.; Hasiotis, S.T. [Indiana State University, Terre Haute, IN (United States). Dept. of Geography Geology & Anthropology


    Euglena mutabilis, a benthic photosynthetic protozoan that intracellularly sequesters Fe, is variably abundant in the main effluent channel that contains acid mine drainage (AMD) discharging from the Green Valley coal mine site in western Indiana. Samples of effluent (pH 3.0-4.6) taken from the main channel and samples of contaminated stream water (pH 3.3 to 8.0) collected from an adjacent stream were analyzed to evaluate the influence of water chemistry on E. mutabilis distribution. E. mutabilis communities were restricted to areas containing unmixed effluent with the thickest (up to 3 mm) benthic communities residing in effluent containing high concentrations of total Fe (up to 12110 mg/l), SO{sub 4}(up to 2940 mg/l), Al (up to 1846 mg/l), and Cl (up to 629 mg/l). Communities were also present, but much less abundant, in areas with effluent containing lower concentrations of these same constituents. In effluent where SO{sub 4} was most highly concentrated, E. mutabilis was largely absent, suggesting that extremely high concentrations of SO{sub 4} may have an adverse effect on this potentially beneficial Fe-mediating, acidophilic protozoan.

  12. Stereotactic Drainage of Brainstem Abscess With the BrainLab Varioguide™ System and the Airo™ Intraoperative CT Scanner: Technical Case Report. (United States)

    Almeida, Cesar C; Uzuner, Ayse; Alterman, Ron L


    Stereotactic biopsies or needle aspirations of posterior fossa lesions are technically challenging. Here we report a novel technique for performing these procedures employing the Airo™ intraoperative computed tomographic (CT) scanner and the VarioGuide™ articulated arm (BrainLab, Munich, Germany). A 62-yr-old woman presented with an irregularly shaped, enhancing lesion of the left pons/middle cerebellar peduncle. Slowed diffusion on magnetic resonance imaging suggested an abscess, but no definitive infectious agent/source could be identified. When the patient deteriorated despite broad-spectrum antibiotic therapy, she was taken to the operating room for stereotactic drainage of the abscess employing the described technique. A specific infectious agent (Eikenella corrodens) was identified from the aspirate, allowing for tailored antibiotic therapy. The procedure was well tolerated and the patient made a full recovery with minimal neurological sequelae. The combination of the Airo™ intraoperative CT and the Varioguide™ articulated arm allows for safe, accurate, and efficient targeting of posterior fossa lesions.

  13. Effective and efficient agricultural drainage pipe mapping with UAS thermal infrared imagery: a case study (United States)

    Effective and efficient methods are needed to map agricultural subsurface drainage systems. Visible (VIS), near infrared (NIR), and/or thermal infrared (TIR) imagery obtained by unmanned aircraft systems (UAS) may provide a means for determining drainage pipe locations. Preliminary UAS surveys wit...

  14. Subdural drainage versus subperiosteal drainage in burr-hole trepanation for symptomatic chronic subdural hematomas. (United States)

    Bellut, David; Woernle, Christoph Michael; Burkhardt, Jan-Karl; Kockro, Ralf Alfons; Bertalanffy, Helmut; Krayenbühl, Niklaus


    Symptomatic chronic subdural hematoma (scSDH) is one of the most frequent diseases in neurosurgical practice, and its incidence is increasing. However, treatment modalities are still controversial. The aim of this retrospective single-center study is to compare for the first time two surgical methods in the treatment of subdural hematoma that have been proven to be efficient in previous studies in a direct comparison. We analyzed the data of 143 scSDHs in 113 patients undergoing surgery for subdural hematoma with placement of subperiosteal or subdural drainage after double burr-hole trepanation for hematoma evacuation. Overall, there were no statistically significant differences regarding general patient characteristics, preoperative and postoperative symptoms, postoperative hematoma remnant, rates of recurrences, mortality, complications, and outcome at discharge and at 3-month follow up between the groups. There was a close to significant tendency of lower mortality after placement of subperiosteal drainage system and a tendency towards lower rate of recurrent hematoma after placement of subdural drainage system. Our study shows for the first time a direct comparison of two mainly used surgical techniques in the treatment of scSDH. Both methods proved to be highly effective, and general patient data, complications, outcome and mortality of both groups are equal or superior compared with previously published series. Because there is a clear tendency to less mortality and fewer serious complications, treatment with double burr-hole trepanation, irrigation, and placement of subperiosteal drainage is our treatment of choice in patients with predictable high risk of complications. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Early and late assessment of internal drainage of chronic dacryocystitis. (United States)

    Mansour, Khaled; Janssen, Alfred G; van Bijsterveld, O Paul


    To evaluate the efficacy of internal drainage of a lacrimal abscess, we treated 10 patients with pyocele of the lacrimal sac, who did not want to undergo operative intervention. A temporary nasolacrimal stent was placed in the nasolacrimal duct, and the pussy material was collected for microbiological examination to adjust the preliminary antibiotic treatment which was given systemically and locally. The stents were removed after the infection had subsided clinically. Three years later, there was a recurrence of the infection in only 1 patient. This internal drainage of the lacrimal sac, combined with systemic and local antibiotics, was successful in 90% of the patients. Copyright 2003 S. Karger AG, Basel

  16. Nutrient behaviour in urban drainages


    Choy, David Kam Wai


    Urbanisation has altered the natural landscape, removing features that previously acted to retain, transform and process nitrogen and phosphorus within catchments. In Melbourne the past legacy of traditional urban design aimed at efficient drainage of stormwater has resulted in higher stormwater volumes with high pollutant concentrations. Excessive concentrations of such nutrients in urban runoff can have an adverse impact on the ecological health of receiving waters. The aims of this stu...

  17. Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes

    Energy Technology Data Exchange (ETDEWEB)

    Grin, A. [Building Science Corporation, Somerville, MA (United States); Lstiburek, J. [Building Science Corporation, Somerville, MA (United States)


    The goal of this research is to provide durable and long-term water management solutions using exterior insulating sheathing as part of the water management system. It is possible to tape or seal the joints in insulating sheathing to create a drainage plane and even an air control layer. There exists the material durability component of the tape as well as the system durability component being the taped insulating sheathing as the drainage plane. This measure guideline provides best practice and product recommendations from the interviewed contractors and homebuilders who collectively have a vast amount of experience. Three significant issues were discussed with the group, which are required to make taped insulating sheathing a simple, long-term, and durable drainage plane: horizontal joints should be limited or eliminated wherever possible; where a horizontal joint exists use superior materials; and frequent installation inspection and regular trade training are required to maintain proper installation.

  18. Preliminary study of the lymphatic drainage system of the nose and paranasal sinuses and its role in detection of sentinel metastatic nodes. (United States)

    Fernández, J M Sánchez; Santaolalla, F; Del Rey, A Sánchez; Martínez-Ibargüen, A; González, A; Iriarte, M Rodríguez


    The normal nasal lymphatic drainage runs via the facial vessels into the neck lymphatic nodes of levels I-II and this drainage pattern was found in our patients with sinonasal tumors. We found only one true-positive sentinel lymph node (SLN). Our pathological material was very limited and so further investigations are required before any valid conclusions can be drawn concerning the clinical value of SLNs in nasal tumors. Objectives. To detect the lymph collection route of the nasal fossae and paranasal sinuses and to identify the first echelon in the tumor metastatic cascade in order to prevent the risk of occult metastases in N0 necks in patients with primary head and neck squamous cell carcinoma (SCC). Our control group comprised 30 patients (20 females; age range 19-50 years) suffering from chronic otitis media who had an anatomically normal nose and a cNO neck on palpation. The pathological group comprised 6 patients (2 females; age range 40-85 years) suffering from sinonasal tumors: 3 SCC, 1 recurrent melanoma, 1 ameloblastoma and 1 inverted papilloma. All had a clinically staged cNO neck on palpation and CT. In the control group, lymphoscintigraphy was carried out by means of unilateral injection of radioactive gold into the head of the inferior turbinate. The tracer was identified using a gamma camera 3 and 6 h after the injection. In the pathological group the chosen tracer was technetium, which was administered 1 day prior to surgery by means of injections into the heads of the inferior and middle turbinates, into the nasal septum and into the retromaxillary gingival mucosa. The tracer was identified transcutaneously using a navigator probe in the gamma camera at 15 min, 30 min and 1 h post-injection. A mark was drawn on the skin corresponding to the hot spot of the SLN. The study was repeated 30 min before surgery. The neck incision was selected according to the location of the SLN. A hand-held gamma probe was used in the operating theatre to detect in

  19. Surgical vs ultrasound-guided drainage of deep neck space abscesses: a randomized controlled trial: surgical vs ultrasound drainage. (United States)

    Biron, Vincent L; Kurien, George; Dziegielewski, Peter; Barber, Brittany; Seikaly, Hadi


    Deep neck space abscesses (DNAs) are relatively common otolaryngology-head and neck surgery emergencies and can result in significant morbidity with potential mortality. Traditionally, surgical incision and drainage (I&D) with antibiotics has been the mainstay of treatment. Some reports have suggested that ultrasound-guided drainage (USD) is a less invasive and effective alternative in select cases. To compare I&D vs USD of well-defined DNAs, using a randomized controlled clinical trial design. The primary outcome measure was effectiveness (length of hospital stay (LOHS) and safety), and the secondary outcome measure was overall cost to the healthcare system. Patients presenting to the University of Alberta Emergency Department with a well-defined deep neck space abscess were recruited in the study. Patients were randomized to surgical or US-guided drainage, placed on intravenous antibiotics and admitted with airway precautions. Following drainage with either intervention, abscess collections were cultured and drains were left in place until discharge. Seventeen patients were recruited in the study. We found a significant difference in mean LOHS between patients who underwent USD (3.1 days) vs I&D (5.2 days). We identified significant cost savings associated with USD with a 41% cost reduction in comparison to I&D. USD drainage of deep neck space abscesses in a certain patient population is effective, safe, and results in a significant cost savings to the healthcare system.

  20. Efficiency of lachrymal sac drainage in newborns with dacryocystocele

    Directory of Open Access Journals (Sweden)

    Sakovich V.N.


    Full Text Available The article represents results of treatment of 14 newborns with unilateral dacryocystocele. Patients age was 7.2±0.5 days. In 9 newborns (64.3% dacryocystocele was complicated with lachrymal sac phlegmon; in 5 children (35.7% any complications were absent. Drainage of lachrymal sac through the lower lachrymal canaliculus, instillation of antibiotics, systemic antibiotic therapy in case of phlegmon were performed in all the children. Lachrymal sac washing was performed with a solution of the antibiotic ofloxacin till clear fluid evacuation. If necessary the drainage was repeated in 10 days. The drainage of lachrymal sac was successful in all the patients. 2-3 weeks after the drainage probing of nasolachrymal duct was perfomed in 4 children (28.6% including those 3 with lacrymal sac phlegmon. In 71.4% regression of dacryocystocele occurred itself. Any complications and side effects were not observed. Positive effect of the drainage, according to the authors, can be explained so that dilatation of lachrymal canaliculus before the procedure allows to eliminate Rosenmьller valve stenosis and evacuation of fluid, mucus and pus, being breeding ground for microorganisms from lachrymal sac, promotes inflammation subsiding. Authors also recommend to pay attention on prenatal diagnosis of dacryocystocele, using ultrasound investigation in the 3rd trimester of pregnancy.

  1. Exocrine drainage in vascularized pancreas transplantation in the new millennium (United States)

    El-Hennawy, Hany; Stratta, Robert J; Smith, Fowler


    The history of vascularized pancreas transplantation largely parallels developments in immunosuppression and technical refinements in transplant surgery. From the late-1980s to 1995, most pancreas transplants were whole organ pancreatic grafts with insulin delivery to the iliac vein and diversion of the pancreatic ductal secretions to the urinary bladder (systemic-bladder technique). The advent of bladder drainage revolutionized the safety and improved the success of pancreas transplantation. However, starting in 1995, a seismic change occurred from bladder to bowel exocrine drainage coincident with improvements in immunosuppression, preservation techniques, diagnostic monitoring, general medical care, and the success and frequency of enteric conversion. In the new millennium, pancreas transplants are performed predominantly as pancreatico-duodenal grafts with enteric diversion of the pancreatic ductal secretions coupled with iliac vein provision of insulin (systemic-enteric technique) although the systemic-bladder technique endures as a preferred alternative in selected cases. In the early 1990s, a novel technique of venous drainage into the superior mesenteric vein combined with bowel exocrine diversion (portal-enteric technique) was designed and subsequently refined over the next ≥ 20 years to re-create the natural physiology of the pancreas with first-pass hepatic processing of insulin. Enteric drainage usually refers to jejunal or ileal diversion of the exocrine secretions either with a primary enteric anastomosis or with an additional Roux limb. The portal-enteric technique has spawned a number of newer and revisited techniques of enteric exocrine drainage including duodenal or gastric diversion. Reports in the literature suggest no differences in pancreas transplant outcomes irrespective of type of either venous or exocrine diversion. The purpose of this review is to examine the literature on exocrine drainage in the new millennium (the purported

  2. Urban drainage design and climate change adaptation decision making

    DEFF Research Database (Denmark)

    Zhou, Qianqian

    mitigation steps have been taken in attempts to reduce global warming, adaptation is highly advocated to supplement mitigation to cope with the unavoidable adverse impacts of flooding on vulnerable assets. The emphasis of this PhD thesis is flood protection in the context of pluvial flooding by investigating...... century, the design objectives of urban drainage systems also include elements such as environmental protection and amenity values. Among the objectives, flood protection has received much attention in recent years as a result of increasing flood hazards and risks due to climate change impacts. Although...... new principles and approaches for assessment of urban drainage adaptation measures under climate change impacts. The thesis describes a new framework for design and analysis of urban drainage that accurately assesses hazards and vulnerabilities of urban areas and quantifies the present and future...

  3. Electronic versus traditional chest tube drainage following lobectomy

    DEFF Research Database (Denmark)

    Lijkendijk, Marike; Licht, Peter B; Neckelmann, Kirsten


    was delegated to staff nurses. Data were analysed by Cox proportional hazard regression model adjusting for lung function, gender, age, BMI, video-assisted thoracic surgery (VATS) or open surgery and presence of incomplete fissure or pleural adhesions. Time was distinguished as possible (optimal) and actual.......014). CONCLUSIONS: Electronic drainage systems did not reduce chest tube duration or length of hospitalization significantly compared with traditional water seal drainage when a strict algorithm for chest tube removal was used. This algorithm allowed delegation of chest tube removal to staff nurses, and in some...

  4. Macrophyte loss drives decadal change in benthic invertebrates in peatland drainage ditches

    NARCIS (Netherlands)

    Whatley, M.H.; van Loon, E.; van Dam, H.; Vonk, J.A.; van der Geest, H.G.; Admiraal, W.


    1. Agricultural peatlands and their associated drainage systems are often highly managed and exposed to anthropogenic pressures, such as eutrophication and stable water tables, maintained via drainage during periods of high rainfall and inlet of, alkaline-rich, waters during dry periods. These

  5. Qualitative and quantitative study on drainage networks at laboratory scale (United States)

    Oliveto, G.; Palma, D.; di Domenico, A.


    Although simulated drainage networks at the laboratory scale would represent highly-simplified models of natural drainages, they would provide a significant contribute to the comprehension of the complex dynamics governing the fluvial systems. Laboratory experiments also give the advantage to detect transient growth phases shedding some light on the knowledge of temporal and spatial landform evolution. Perhaps, pioneering laboratory experiments on drainage network evolution were carried out in 1977 at REF (Rainfall Erosion Facility) of Colorado State University by Schumm and co-workers. This study deals with an analysis of physical experiments simulating the evolution and the development of drainage networks. To this purpose, some experiments were carried out at University of Basilicata by using a 1.5 m by 1.5 m box-basin-simulator with an outlet incised in the middle of the downslope-end side. The experimental landscape was made of a weakly cohesive soil mainly constituted by clay and silt. A system of microsprinklers generated an almost uniform artificial precipitation. Simulations were performed at a constant rainfall rate with intensity of 100 mm/h. In total four experiments were carried out. Three of those were conducted by ensuring consistent initial conditions except for the initial landscape planar slope of 9%, 5%, and 0.6%, respectively. The remaining experiment was performed with a landscape slope of 9% again, but with the (surface) base-level coinciding with the base of the outlet (i.e. streams could not erode below the base-level). Despite the central outlet constraint, the generated stream system for the 9% plane exhibited trellis-like drainage patterns with many short tributaries joining the main stream at nearly right angles. For the 5% experiment still sub-parallel drainage patterns were formed but mainly in the centre of the watershed. Channels were clearly shallower than those of the 9% experiment. For the gentler slope of 0.6% dendritic drainage

  6. Peritoneal drainage versus laparotomy as an initial treatment in ...

    African Journals Online (AJOL)

    Insertion of a PD is still useful in resuscitating small critically ill infants with NEC; however, the majority of these infants will require subsequent laparotomy. Early diagnosis and early intervention are necessary to decrease the inflammatory insults to the body systems and this reflects on survival. Keywords: drainage versus ...

  7. Internal hydraulics of an agricultural drainage denitrification bioreactor (United States)

    Denitrification bioreactors to reduce the amount of nitrate-nitrogen in agricultural drainage are now being deployed across the U.S. Midwest. However, there are still many unknowns regarding internal hydraulic-driven processes in these "black box" engineered treatment systems. To improve this unders...

  8. Selecting Suitable Drainage Pattern to Minimize Flooding in ...

    African Journals Online (AJOL)

    Water shed analysis is a geographic information system (GIS) based technique designed to model the way surface water flows on the earth surface. This was the method adopted to select suitable drainage pattern to minimized flood in some parts of sangere. The process of watershed computes the local direction of flow ...

  9. Mine Drainage Generation and Control Options. (United States)

    Wei, Xinchao; Rodak, Carolyn M; Zhang, Shicheng; Han, Yuexin; Wolfe, F Andrew


    This review provides a snapshot of papers published in 2015 relevant to the topic of mine drainage generation and control options. The review is broken into 3 sections: Generation, Prediction and Prevention, and Treatment Options. The first section, mine drainage generation, focuses on the characterization of mine drainage and the environmental impacts. As such, it is broken into three subsections focused on microbiological characterization, physiochemical characterization, and environmental impacts. The second section of the review is divided into two subsections focused on either the prediction or prevention of acid mine drainage. The final section focuses on treatment options for mine drainage and waste sludge. The third section contains subsections on passive treatment, biological treatment, physiochemical treatment, and a new subsection on beneficial uses for mine drainage and treatment wastes.

  10. Subglacial biochemical weathering and transport drove fertilization in the Southern Ocean during Antarctic temperature maxima and NH Heinrich events (United States)

    Frisia, S.; Augustinus, P. M.; Hellstrom, J.; Borsato, A.; Drysdale, R.; Weyrich, L.; Cooper, A.; Johnston, V. E.; Cotte, M.


    Changes in bioproductivity in the subantarctic region have been observed to coincide with episodes of significant iceberg discharge in the North Atlantic (Heinrich events), thus linking iron delivery to the Southern Ocean (SO) with abrupt climate changes in the Northern Hemisphere. Whilst upwelling has been proposed as a likely source of bioavailable iron during Heinrich events, it is well known that, today, subglacial metabolic pathways under limited carbon supply may accumulate divalent iron, which could have been mobilized and delivered to the SO during full glacial conditions. This alternative hypothesis remains largely untested for the SO because of the difficulties in accessing palaeoenvironmental archives from beneath the Antarctic ice sheets. We present a record of the subglacial production and fate of nutrients from calcite crusts formed beneath a tributary of the Rennick outlet glacier (East Antarctic Ice Sheet, EAIS) during the Last Glacial Maximum. Chemistry, stratigraphy and preliminary ancient DNA characterization of the microbial consortium of 27- to 17-kyr-old calcites suggest that bioweathering released iron in hypoxic pools of local basal meltwater. Anaerobic methane oxidising microbes released bicarbonate and sulfuric acid in the isolated pockets, which facilitated local weathering of the amphibolite rock. During episodes of channelized flow, identified by clast-rich microsparites, and which have ages near-commensurate with Antarctic Isotope Maximum2 (AIM2) and Heinrich event 2, ferrous iron may have been mobilized and transported subglacially to the ice shelf. The calcites formed during this phase preserve evidence of microbes using sulfite dehydrogenase, which explains the accumulation of sulfate in the calcite. Our data thus indicate that subglacial processes contributed to SO productivity increases at the time of Heinrich event 2, ultimately leading to drawdawn of atmospheric carbon dioxide at millennial scale.

  11. Composite fibrous glaucoma drainage implant (United States)

    Klapstova, A.; Horakova, J.; Shynkarenko, A.; Lukas, D.


    Glaucoma is a frequent reason of loss vision. It is usually caused by increased intraocular pressure leading to damage of optic nerve head. This work deals with the development of fibrous structure suitable for glaucoma drainage implants (GDI). Commercially produced metallic glaucoma implants are very effective in lowering intraocular pressure. However, these implants may cause adverse events such as damage to adjacent tissue, fibrosis, hypotony or many others [1]. The aim of this study is to reduce undesirable properties of currently produced drains and improve their properties by creating of the composite fibrous drain for achieve a normal intraocular pressure. Two types of electrospinning technologies were used for the production of very small tubular implants. First type was focused for production of outer part of tubular drain and the second type of electrospinning method made the inner part of shape follows the connections of both parts. Complete implant had a special properties suitable for drainage of fluid. Morphological parameters, liquid transport tests and in-vitro cell adhesion tests were detected.

  12. Palaeogeographical And Archaeological Records Of Natural Changes Of The Jordanowo-Niesulice Subglacial Channel Near Lubrza, The Lubusz Lakeland

    Directory of Open Access Journals (Sweden)

    Ratajczak-Szczerba Magdalena


    Full Text Available The region of the Lubusz Lakeland in western Poland where there are a lot of subglacial channels provides opportunity for multi-proxy palaeoenvironmental reconstructions. None of them has not been the object of a specific study. The developmental history of the palaeolakes and their vicinity in the subglacial trough Jordanowo-Niesulice, spanning the Late Glacial and beginning of the Holocene, was investigated using geological research, lithological and geomorphological analysis, geochemical composition, palynological and archaeological research, OSL and AMS-radiocarbon dating. Geological research shows varied morphology of subglacial channel where at least two different reservoirs functioned in the end of the Last Glacial period and at the beginning of the Holocene. Mostly during the Bølling-Allerød interval and at the beginning of the Younger Dryas there took place melting of buried ice-blocks which preserved the analysied course of the Jordanowo-Niesulice trough. The level of water, and especially depth of reservoirs underwent also changes. Palynological analysis shows very diversified course of the Allerød interval.

  13. Drainage basin delineations for selected USGS streamflow-gaging stations in Virginia (Drainage_Basin) (United States)

    U.S. Geological Survey, Department of the Interior — The Drainage_Basin polygon feature class was created as a digital representation of drainage basins for more than 1,650 continuous-record streamflow-gaging stations,...

  14. Inferring the tectonic setting of the Gamburtsev Subglacial Mts by ice cap surface lineaments (United States)

    Cianfarra, Paola; Salvini, Francesco


    Gamburtsev Subglacial Mts (GSM) are by far one of the most puzzling physiographic feature of the East Antactic craton. Located at the centre of the Antarctic continent and beneath the highest point of East Antarctic Ice Sheet (Dome A) they were discovered during the 1957-58 International Geophysical Year by a Soviet expedition using seismic instruments to measure the thickness of the ice sheet. This intracratonic mountain range is characterised by peaks with elevation exceeding 3500 m and covers an area bigger than the European Alps. The GSM were the target of a huge international geophysical expedition during the 2008-2009 summer season with the aim of revealing the geologic nature and origin of this mountain range, as well as to further understand the tectonic setting of two of the largest Antarctic subglacial lakes bounding to the East and to the West the GSM, namely the Vostok and Recovery lakes. Preliminary results of this international scientific campaign have been presented to the scientific community and showed that the GSM are characterised by a typical alpine landscape with a rectangular hydrographic network. These morphological features are commonly associated to recent/active tectonics. At present, four scenarios exists to explain the existence of such intracratonic mountain range: (i) a hot-spot beneath the Antarctic crust, in a Hoggar-like mantle plume scenario; (ii) a continental collision (of unknown age) similarly to the Alpine orogenic belt; (iii) a rifting process associated to flexural uplift or isostatic rebound of the rift shoulder, in a Transantarctic Mts like scenario or similarly to the mountains along the edges of the East African rift lakes; and (iv) a continental arching related to regional, continental-scale stress like the Black Hills in the North America continent or the russian platform arching located NE of Moscow. These geodynamic scenarios are characterised by different morpho-tectonic signatures that can be successfully

  15. Conceptual design report for site drainage control

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, M.R.


    The Mound Plant (Mound), located in Miamisburg, Ohio, is a Department of Energy (DOE) development and production facility performing support work for DOE`s weapons and energy-related programs. EG&G Mound Applied Technologies, Inc. (EG&G) is the Operating Contractor (OC) for this Government-Owned, Contractor-Operated (GOCO) facility. The work performed at Mound emphasizes nuclear energy and explosives technology. Mound is currently implementing an Environmental, Safety & Health (ES&H) Upgrades Program designed to protect its employees, the public, and the environment from adverse effects caused by facility activities. The first project of this multiphase program is now in the final stages of construction, and the second project is currently under design. Four additional projects, one of which is presented in this report, are in the conceptual design stage. At Mound, 22 soil zones have become contaminated with radioactive material. These zones cover approximately 20 percent of the total area of developed property at the site. During a storm event, the rainwater washes contaminated soil from these zones into the storm sewer system. These radioactive contaminants may then be discharged along with the stormwater into the Great Miami River via the Miami Erie Canal. This conceptual design report (CDR), Site Drainage Control, the fourth project in the ES&H program, describes a project that will provide improvements and much needed repairs to inadequate and deteriorating portions of the storm drainage system on the developed property. The project also will provide a stormwater retention facility capable of storing the stormwater runoff, from the developed property, resulting from a 100-year storm event. These improvements will permit the effective control and monitoring of stormwater to prevent the spread of radioactive contaminants from contaminated soil zones and will provide a means to collect and contain accidental spills of hazardous substances.

  16. Occurrence of amphibians in northern California coastal dune drainages (United States)

    Halstead, Brian J.; Kleeman, Patrick M.


    Many coastal dune ecosystems have been degraded by non-native dune vegetation, but these systems might still provide valuable habitat for some taxa, including amphibians. Because restoration of degraded dune systems is occurring and likely to continue, we examined the occurrence of amphibians in drainages associated with a coastal dune ecosystem degraded by invasive plants (European Beachgrass, Ammophila arenaria, and Iceplant, Carpobrotus edulis). We found that occupancy of 3 amphibian species (California Red-legged Frog, Rana draytonii; Sierran Treefrog, Hyliola sierra; and Rough-skinned Newt, Taricha granulosa) among 21 coastal-dune drainages was high, with most coastal-dune drainages occupied by all 3 species. Furthermore, reproduction of Sierran Treefrogs and California Red-legged Frogs was estimated to occur in approximately ½ and ⅓ of the drainages, respectively. The probability of occurrence of Rough-skinned Newts and pre-metamorphic life stages of both anurans decreased during the study, perhaps because of ongoing drought in California or precipitation-induced changes in phenology during the final year of the study. Maintaining structural cover and moist features during dune restoration will likely benefit native amphibian populations inhabiting coastal-dune ecosystems.

  17. IDA: An implicit, parallelizable method for calculating drainage area (United States)

    Richardson, Alan; Hill, Christopher N.; Perron, J. Taylor


    Models of landscape evolution or hydrological processes typically depend on the accurate determination of upslope drainage area from digital elevation data, but such calculations can be very computationally demanding when applied to high-resolution topographic data. To overcome this limitation, we propose calculating drainage area in an implicit, iterative manner using linear solvers. The basis of this method is a recasting of the flow routing problem as a sparse system of linear equations, which can be solved using established computational techniques. This approach is highly parallelizable, enabling data to be spread over multiple computer processors. Good scalability is exhibited, rendering it suitable for contemporary high-performance computing architectures with many processors, such as graphics processing units (GPUs). In addition, the iterative nature of the computational algorithms we use to solve the linear system creates the possibility of accelerating the solution by providing an initial guess, making the method well suited to iterative calculations such as numerical landscape evolution models. We compare this method with a previously proposed parallel drainage area algorithm and present several examples illustrating its advantages, including a continent-scale flow routing calculation at 3 arc sec resolution, improvements to models of fluvial sediment yield, and acceleration of drainage area calculations in a landscape evolution model. We additionally describe a modification that allows the method to be used for parallel basin delineation.

  18. Design and assessment of urban drainage and water reuse systems for the reconstruction of formerly industrial areas: a case in Beijing. (United States)

    Liu, L; Zeng, S; Dong, X; Chen, J


    The Shougang Group is an industrial steel enterprise occupying 800 ha in Beijing that will cease production by 2010. The area will be converted to a new financial and commercial zone. The rebuilding of the water infrastructure in this area should address water shortages in Beijing and retain the industrial landmark of a large cooling water tank. A design framework and an assessment system with 11 indicators were developed for this purpose. Four reconstruction schemes are presented here. Scheme 1 is a traditional system that completely depends on outside the municipal facility. Schemes 2, 3, and 4 are systems to separately discharge greywater and blackwater. Scheme 4 uses a vacuum system that allows the reclamation of nutrients. Schemes 2 and 4 use wetland-treated greywater to fill the water tank. Scheme 3 reuses greywater for toilets after on-site treatment. Scheme 2 is recommended due to its lower cost, greater environmental benefit, moderate resource reclamation, and higher technical feasibility.

  19. Near-glacier surveying of a subglacial discharge plume: Implications for plume parameterizations (United States)

    Jackson, R. H.; Shroyer, E. L.; Nash, J. D.; Sutherland, D. A.; Carroll, D.; Fried, M. J.; Catania, G. A.; Bartholomaus, T. C.; Stearns, L. A.


    At tidewater glaciers, plume dynamics affect submarine melting, fjord circulation, and the mixing of meltwater. Models often rely on buoyant plume theory to parameterize plumes and submarine melting; however, these parameterizations are largely untested due to a dearth of near-glacier measurements. Here we present a high-resolution ocean survey by ship and remotely operated boat near the terminus of Kangerlussuup Sermia in west Greenland. These novel observations reveal the 3-D structure and transport of a near-surface plume, originating at a large undercut conduit in the glacier terminus, that is inconsistent with axisymmetric plume theory, the most common representation of plumes in ocean-glacier models. Instead, the observations suggest a wider upwelling plume—a "truncated" line plume of ˜200 m width—with higher entrainment and plume-driven melt compared to the typical axisymmetric representation. Our results highlight the importance of a subglacial outlet's geometry in controlling plume dynamics, with implications for parameterizing the exchange flow and submarine melt in glacial fjord models.

  20. Evaluating the hydrostatic equilibrium of the subglacial Lake Vostok, Antarctica, using a precise regional geoid model (United States)

    Schwabe, Joachim; Ewert, Heiko; Scheinert, Mirko; Dietrich, Reinhard


    We present a study on the determination and application of a precise geoid model for the region of the subglacial Lake Vostok, Antarctica. The geoid model is derived by combining a global satellite-only geopotential model mainly based on GOCE data with dense airborne gravity data and topographic information. Ice-thickness data and lake water depths are used for a residual terrain modelling (RTM) in a remove-restore approach. In that context, special focus is given to the correct treatment of the ice sheet when computing the residual terrain effects. The use of the refined regional geoid model for glaciological and geophysical applications is exemplarily demonstrated by means of the hydrostatic equilibrium surface (HE) of the lake. It was found that the mean quadratic residual geoid signal is about two times larger than the estimated deviations of the HE surface. Thus, the significance of the refined geoid solution is proven. In this context, a comparison with the strictly computed geopotential shows that the estimated apparent lake level may be expressed as a constant metric bias w.r.t. to the quasigeoid. Furthermore, the HE condition is used to derive an adjusted estimate of the lake water density. However, in this case the theoretical latitudinal trend of the equilibrium surface needs to be taken into account. Finally, the (hypothetical) deviations from the HE state at and around the shoreline of the lake indicate candidate outflow locations in case of a possible depletion event.

  1. Ecology of Subglacial Lake Vostok (Antarctica, Based on Metagenomic/Metatranscriptomic Analyses of Accretion Ice

    Directory of Open Access Journals (Sweden)

    Tom D'Elia


    Full Text Available Lake Vostok is the largest of the nearly 400 subglacial Antarctic lakes and has been continuously buried by glacial ice for 15 million years. Extreme cold, heat (from possible hydrothermal activity, pressure (from the overriding glacier and dissolved oxygen (delivered by melting meteoric ice, in addition to limited nutrients and complete darkness, combine to produce one of the most extreme environments on Earth. Metagenomic/metatranscriptomic analyses of ice that accreted over a shallow embayment and over the southern main lake basin indicate the presence of thousands of species of organisms (94% Bacteria, 6% Eukarya, and two Archaea. The predominant bacterial sequences were closest to those from species of Firmicutes, Proteobacteria and Actinobacteria, while the predominant eukaryotic sequences were most similar to those from species of ascomycetous and basidiomycetous Fungi. Based on the sequence data, the lake appears to contain a mixture of autotrophs and heterotrophs capable of performing nitrogen fixation, nitrogen cycling, carbon fixation and nutrient recycling. Sequences closest to those of psychrophiles and thermophiles indicate a cold lake with possible hydrothermal activity. Sequences most similar to those from marine and aquatic species suggest the presence of marine and freshwater regions.

  2. Visual drainage assessment: A standardised visual soil assessment method for use in land drainage design in Ireland

    Directory of Open Access Journals (Sweden)

    Tuohy P.


    Full Text Available The implementation of site-specific land drainage system designs is usually disregarded by landowners in favour of locally established ‘standard practice’ land drainage designs. This is due to a number of factors such as a limited understanding of soil–water interactions, lack of facilities for the measurement of soil’s physical or hydrological parameters and perceived time wastage and high costs. Hence there is a need for a site-specific drainage system design methodology that does not rely on inaccessible, time-consuming and/or expensive measurements of soil physical or hydrological properties. This requires a standardised process for deciphering the drainage characteristics of a given soil in the field. As an initial step, a new visual soil assessment method, referred to as visual drainage assessment (VDA, is presented whereby an approximation of the permeability of specific soil horizons is made using seven indicators (water seepage, pan layers, texture, porosity, consistence, stone content and root development to provide a basis for the design of a site-specific drainage system. Across six poorly drained sites (1.3 ha to 2.6 ha in size in south-west Ireland a VDA-based design was compared with (i an ideal design (utilising soil physical measurements to elucidate soil hydraulic parameters and (ii a standard design (0.8 m deep drains at a 15 m spacing by model estimate of water table control and rainfall recharge/drain discharge capacity. The VDA method, unlike standard design equivalents, provided a good approximation of an ideal (from measured hydrological properties design and prescribed an equivalent land drainage system in the field. Mean modelled rainfall recharge/drain discharge capacity for the VDA (13.3 mm/day and ideal (12.0 mm/day designs were significantly higher (P < 0.001, s.e. 1.42 mm/day than for the standard designs (0.5 mm/day, when assuming a design minimum water table depth of 0.45 m.

  3. Analysing aeromagnetic, airborne gravity and radar data to unveil variable basal boundary conditions for the East Antarctic Ice Sheet in the Wilkes Subglacial Basin (United States)

    Armadillo, Egidio; Ferraccioli, Fausto; Young, Duncan; Balbi, Pietro; Blankenship, Don; Jordan, Tom; Bozzo, Emanuele; Siegert, Martin


    ), but is unlikely to be strongly affected by Cretaceous or Cenozoic-age rifting, in contrast to the WAIS, which is largely underlain by the West Antarctic Rift System; iii) its bedrock is composed of rocks of different ages and composition, including Proterozoic basement, Neoproterozoic and Cambrian sediments intruded by Cambrian arc rocks, and cover rocks formed primarily by Beacon sediments intruded by Jurassic Ferrar sills (e.g. Cook et al., 2013 Nature Geoscience). Within the framework of the collaborative Italian-US-UK BABOC project a new international initiative has been launched to analyse and model variable geological boundary conditions in the WSB using geophysical data. A large amount of new ICECAP aerogeophysical observations have been acquired over four campaigns over the region since the International Polar Year, in particular over the southern part of the basin, and some profiles over the northern coastal margin of the basin. We will present an initial interpretation of the potential field signatures and radar data over the northern and central parts of the basin to help establish tectonic and lithological controls on the subglacial topography and different EAIS flow regimes within the WSB.

  4. Design principles for lymphatic drainage of fluid and solutes from collagen scaffolds. (United States)

    Thompson, Rebecca L; Margolis, Emily A; Ryan, Tyler J; Coisman, Brent J; Price, Gavrielle M; Wong, Keith H K; Tien, Joe


    In vivo, tissues are drained of excess fluid and macromolecules by the lymphatic vascular system. How to engineer artificial lymphatics that can provide equivalent drainage in biomaterials remains an open question. This study elucidates design principles for engineered lymphatics, by comparing the rates of removal of fluid and solute through type I collagen gels that contain lymphatic vessels or unseeded channels, or through gels without channels. Surprisingly, no difference was found between the fluid drainage rates for gels that contained vessels or bare channels. Moreover, solute drainage rates were greater in collagen gels that contained lymphatic vessels than in those that had bare channels. The enhancement of solute drainage by lymphatic endothelium was more pronounced in longer scaffolds and with smaller solutes. Whole-scaffold imaging revealed that endothelialization aided in solute drainage by impeding solute reflux into the gel without hindering solute entry into the vessel lumen. These results were reproduced by computational models of drainage with a flow-dependent endothelial hydraulic conductivity. This study shows that endothelialization of bare channels does not impede the drainage of fluid from collagen gels and can increase the drainage of macromolecules by preventing solute transport back into the scaffold. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 106-114, 2018. © 2017 Wiley Periodicals, Inc.

  5. Models Robustness for Simulating Drainage and NO3-N Fluxes (United States)

    Jabro, Jay; Jabro, Ann


    Computer models simulate and forecast appropriate agricultural practices to reduce environmental impact. The objectives of this study were to assess and compare robustness and performance of three models -- LEACHM, NCSWAP, and SOIL-SOILN--for simulating drainage and NO3-N leaching fluxes in an intense pasture system without recalibration. A 3-yr study was conducted on a Hagerstown silt loam to measure drainage and NO3-N fluxes below 1 m depth from N-fertilized orchardgrass using intact core lysimeters. Five N-fertilizer treatments were replicated five times in a randomized complete block experimental design. The models were validated under orchardgrass using soil, water and N transformation rate parameters and C pools fractionation derived from a previous study conducted on similar soils under corn. The model efficiency (MEF) of drainage and NO3-N fluxes were 0.53, 0.69 for LEACHM; 0.75, 0.39 for NCSWAP; and 0.94, 0.91for SOIL-SOILN. The models failed to produce reasonable simulations of drainage and NO3-N fluxes in January, February and March due to limited water movement associated with frozen soil and snow accumulation and melt. The differences between simulated and measured NO3-N leaching and among models' performances may also be related to soil N and C transformation processes embedded in the models These results are a monumental progression in the validation of computer models which will lead to continued diffusion across diverse stakeholders.

  6. Use of land located within Eselnita drainage basin

    Directory of Open Access Journals (Sweden)



    Full Text Available Developed on the south-eastern side of Almãjului Mountains, Eşelniţa drainage basin neighbours upon the following basins: upon S – SV with Mala, upon SV - V with Mraconia, upon V - NV with Berzasca, upon NV - NNE with Nera and on the NNE – SE direction with Cerna. The basin has a surface of 77 km2 and present a 5th degree hydrographic network according to Horton-Strahler ranking system, tributary to Danube by means of Eşelniţa main collector. Among surfaces belonging to various categories of use of land located within Eselnita drainage basin, there may be noticed the high share of forest and secondary grazing lands, although the latter have a smaller surface in comparison to the first ones. Therefore, the types of use of land located within the drainage basin are distinguished by the high share of surfaces of forests to the detriment of predominant agricultural land proven by using of some quantitative indexes defining the character of the Eselnita drainage basin as belonging to forestry type. Also the impact of human activities and number of inhabitants do not have a very damaging influence on the land corresponding to the basin, therefore it has a naturality index indicating an ecological equilibrium closed to the natural one.

  7. Visualization of fluid drainage pathways in lymphatic vessels and lymph nodes using a mouse model to test a lymphatic drug delivery system. (United States)

    Kodama, Tetsuya; Hatakeyama, Yuriko; Kato, Shigeki; Mori, Shiro


    Curing/preventing micrometastasis to lymph nodes (LNs) located outside the surgically resected area is essential for improving the morbidity and mortality associated with breast cancer and head and neck cancer. However, no lymphatic therapy system exists that can deliver drugs to LNs located outside the dissection area. Here, we demonstrate proof of concept for a drug delivery system using MXH10/Mo-lpr/lpr mice that exhibit systemic lymphadenopathy, with some peripheral LNs being as large as 10 mm in diameter. We report that a fluorescent solution injected into the subiliac LN (defined as the upstream LN within the dissection area) was delivered successfully to the proper axillary LN (defined as the downstream LN outside the dissection area) through the lymphatic vessels. Our results suggest that this approach could be used before surgical resection to deliver drugs to downstream LNs outside the dissection area. We anticipate that our methodology could be applied clinically, before surgical resection, to cure/prevent micrometastasis in LNs outside the dissection area, using techniques such as ultrasound-guided internal jugular vein catheterization.

  8. The influence of environmental factors and dredging on chironomid larval diversity in urban drainage systems in polders strongly influenced by seepage from large rivers

    DEFF Research Database (Denmark)

    Vermonden, K.; Brodersen, Klaus Peter; Jacobsen, Dean


    different chironomid associations were distinguished by Two-Way Indicator Species Analysis. Variation within and among chironomid associations were significantly related to substrate (sludge layer and substrate type: sand vs clay), %% cover of lemnids, submerged vegetation, filamentous algae, and water...... transparency. Chironomid taxon richness and H' were similar in urban and rural waters, probably because of their similar hydrologic, morphologic, and water-quality conditions and their similar dredging and weed-control regimes. Rareness was slightly higher in urban than in rural waters. In urban water systems...

  9. Long hole waterjet drilling for gas drainage

    Energy Technology Data Exchange (ETDEWEB)

    Matt Stockwell; M. Gledhill; S. Hildebrand; S. Adam; Tim Meyer [CMTE (Australia)


    In-seam drilling for gas drainage is now an essential part of operations at many Australian underground coalmines. The objective of this project is to develop and trial a new drilling method for the accurate and efficient installation of long inseam boreholes (>1000 metres). This involves the integration of pure water-jet drilling technology (i.e. not water-jet assisted rotary drilling) developed by CMTE with conventional directional drilling technology. The system was similar to conventional directional drilling methods, but instead of relying on a down-hole-motor (DHM) rotating a mechanical drill bit for cutting, high pressure water-jets were used. The testing of the system did not achieve the full objectives set down in the project plan. A borehole greater than 1000 metres was not achieved. The first trial site had coal that was weathered, oxidized and dry. These conditions significantly affected the ability of the drilling tool to stay 'in-seam'. Due to the poor conditions at the first trial, many experimental objectives were forwarded to the second field trial. In the second trial drilling difficulties were experienced, this was due to the interaction between the confinement of the borehole and the dimensions of the down hole drilling assembly. This ultimately reduced the productivity of the system and the distance that could be drilled within the specified trial periods. Testing in the first field trial did not show any indication that the system would have this difficulty.

  10. Orthotopic small intestine transplantation in dogs with systemic graft drainage Transplante ortotópico de intestino delgado em cães com drenagem sistêmica do enxerto

    Directory of Open Access Journals (Sweden)

    Flávio Henrique Ferreira Galvão


    Full Text Available BACKGROUND: Small intestine transplantation has been accepted worldwide to treat complex cases of intestinal failure. Canine intestinal transplantation model is important in training the surgical technique and to study the complications of this procedure. Systemic graft venous drainage is frequently performed in clinic, although the consequences of this partial meso-caval shunt have not been studied in detail. AIM: To describe the surgical technique and clinical outcome of a canine intestinal transplantation model using mesenteric-caval graft drainage. METHOD: Adult mongrel dogs from University of São Paulo Animal Facility, São Paulo, SP, Brazil, were used as donors and recipients in ten consecutives orthotopic intestinal transplantation with mesenteric-caval venous drainage. Clinical examination and body weight measurement were performed daily in all animals. Necropsy was performed in animals presenting moribund state (lethargic posture, diarrhea and loss of over 35% of body weight to determine cause of death and histological changes. RESULTS: Three recipients died before day 2 from technical complications and were excluded from the experiment. The remaining seven animals developed signs of graft rejection with onset on days 3-4 and died or were sacrificed presenting severe graft rejection between days 7-9. Necropsy and histology of the graft confirmed the diagnosis of severe acute cellular rejection. CONCLUSION: Small intestine transplantation with systemic drainage in dogs courses with analogous and lethal outcome between postoperative day 7 to 9 due to strong graft rejection. This model serves as an excellent pre-clinical model to study the main complications related to this transplantation.RACIONAL: O transplante de intestino delgado é atualmente indicado para tratar casos complexos de falência entérica. Transplante intestinal em cão é importante modelo experimental para treino da técnica cirúrgica e para estudar as complica

  11. Systematic review and meta-analysis of closed suction drainage versus non-drainage in primary hip arthroplasty.

    LENUS (Irish Health Repository)

    Kelly, Enda G


    The routine use of drains in surgery has been dogmatically instituted in some disciplines. Orthopaedic surgery is one such sub-speciality. The use of postoperative closed suction drainage in total hip arthroplasty (THA) has become increasingly controversial with multiple randomised control trials performed to assess the benefit to outcome in THA. The hypothesis of this systematic review is that closed suction drainage does not infer a benefit and increase transfusion requirements of primary total hip arthroplasty patients. A systematic review and meta-analysis was conducted adhering to the PRISMA guidelines. A search of the available literature was performed on PubMed, Cochrane Central Registry of Controlled Trials, MEDLINE (OVID) and EMBASE using a combination of MeSH terms and Boolean operators. All data analysis was performed using the Cochrane Collaboration\\'s Review Manager 5.1. Sixteen studies (n=2705) were included in the analysis. Post-operative closed suction drainage was found to increase total blood loss and blood transfusion requirements (p<0.05). Surgical site infection demonstrated no significant difference between the two groups (p=0.82). No significant difference in haematoma formation between groups (p=0.19) was elicited. The routine use of closed suction drainage systems post primary hip arthroplasty is not supported by this meta-analysis. However, the heterogeneity between studies does limit the accuracy of the meta-analysis.

  12. Nondestructive evaluation of the condition of subsurface drainage in pavements using ground penetrating radar (GPR). (United States)


    Subsurface drainage features are routinely incorporated in the design of pavement systems as they are believed to increase pavement service life provided that they are installed correctly and maintained. Maintenance, however, is challenging in that l...

  13. Digital database architecture and delineation methodology for deriving drainage basins, and a comparison of digitally and non-digitally derived numeric drainage areas (United States)

    Dupree, Jean A.; Crowfoot, Richard M.


    The drainage basin is a fundamental hydrologic entity used for studies of surface-water resources and during planning of water-related projects. Numeric drainage areas published by the U.S. Geological Survey water science centers in Annual Water Data Reports and on the National Water Information Systems (NWIS) Web site are still primarily derived from hard-copy sources and by manual delineation of polygonal basin areas on paper topographic map sheets. To expedite numeric drainage area determinations, the Colorado Water Science Center developed a digital database structure and a delineation methodology based on the hydrologic unit boundaries in the National Watershed Boundary Dataset. This report describes the digital database architecture and delineation methodology and also presents the results of a comparison of the numeric drainage areas derived using this digital methodology with those derived using traditional, non-digital methods. (Please see report for full Abstract)

  14. Mineralogy and geochemistry of Zn-rich mine-drainage precipitates from an MgO passive treatment system by synchrotron-based X-ray analysis. (United States)

    Pérez-López, Rafael; Macías, Francisco; Caraballo, Manuel A; Nieto, José Miguel; Román-Ross, Gabriela; Tucoulou, Rémi; Ayora, Carlos


    Synchrotron radiation-induced micro-X-ray analysis were applied to characterize the newly formed phases that precipitate in a passive treatment system using magnesium oxide to remove high concentrations of zinc (ca. 440 mg/L) and other minor metals from neutral pretreated waters in the Iberian Pyrite Belt (SW Iberian Peninsula). Micro-X-ray fluorescence (μ-XRF) maps of polished samples were used to find spatial correlations among metals, pinpointing zones of interest where micro-X-ray diffraction (μ-XRD) data were exploited to identify the mineral phases responsible for metal retention. This coupled technique identified hydrozincite (Zn(5)(CO(3))(2)(OH)(6)) and minor loseyite ((Mn,Zn)(7)(CO(3))(2)(OH)(10)) as the mineral sinks for Zn and also other potentially toxic elements such as Co and Ni. Although hydrozincite retains traces of Mn, this metal is mainly retained by precipitation of loseyite. The precipitation of zinc hydroxy-carbonates and their ability to uptake other metals (Mn, Co, and Ni) is hence of potential interest not only for the treatment of contaminated waters but also for the generation of a solid waste that could be exploited as a new Zn economic resource.

  15. Public open spaces: utiization of green infrastructure to optimize urban drainage in historic property


    Claudione Fernandes Medeiros; Sônia Afonso


    Climate change affects city life. Extreme events, such as temperature rising, droughts, and floods, also threaten cultural heritage. In historic city centers, floods and heavy rain have caused pathologies in properties and streets. The traditional urban drainage system has shown to be inefficient, in addition to the difficulties of expanding this system due to pre-existing matters. This study seeks to use public open spaces in historic city centers to improve urban drainage, through the conce...

  16. Gravity Drainage Kinetics of Papermaking Fibrous Suspensions

    Directory of Open Access Journals (Sweden)

    Przybysz Piotr


    Full Text Available The study analyses application possibilities of filtration and thickening models in evaluation of papermaking suspension drainage rate. The authors proposed their own method to estimate the drainage rate on the basis of an existing Ergun capillary model of liquid flow through a granular material. The proposed model was less sensitive to porosity changes than the Ergun model. An empirical verification proved robustness of the proposed approach. Taking into account discrepancies in the published data concerning how the drainage velocity of papermaking suspension is defined, this study examines which of the commonly applied models matches experimental results the best.

  17. Transformation of heavy metal fractionation under changing environments: a case study of a drainage system in an e-waste dismantling community. (United States)

    Damrongsiri, Seelawut


    The change in environmental conditions during the transportation of contaminated soil and sediment was expected to affect the transformation of heavy metal fractionation. This study disclosed the serious contamination of copper (Cu), lead (Pb), and zinc (Zn) in the sewer sediment of an e-waste dismantling community in Thailand which may be caused by flushed contaminated soil and e-waste fragments. Two environmental conditions were simulated to observe the transformation of heavy metal fractionation. The anoxic sewer condition was induced using high substrate and sulfate in a closed container. The aeration of anoxic contaminated sediment was applied to simulate the transformation to an oxidative environment. The BCR sequential extraction was applied for heavy metal fractionation in this study. The study results exhibited that when heavy metal contaminated soil was transferred into this induced anoxic condition, fractionation was redistributed based on the chemical change of system that tends to be associated into F3 (oxidizable fraction) > F2 (reducible fraction) > F1 (acid soluble/exchangeable fraction). Cu exhibited the outstanding capability association to F3. The iron sulfide was not observed as usual due to its lower capability than Cu, Pb, and Zn. When contaminated sediment was transported to a more oxidative environment, the heavy metals fractionation would be redistributed again among those new environment media. It is noteworthy that F3 of Cu was stable even in oxic conditions. F2 of Fe was not developed by this oxic condition, possibly because its dehydration process was limited. The redistribution under an oxic environment became F1 > F2 > F3 indicating their more available form. This transformation was imperative and should be taken into account in heavy metal contaminated site management and control.

  18. The persistence of lead from past gasoline emissions and mining drainage in a large riparian system: Evidence from lead isotopes in the Sacramento River, California (United States)

    Dunlap, C. E.; Alpers, C. N.; Bouse, R.; Taylor, H. E.; Unruh, D. M.; Flegal, A. R.


    Lead concentrations and isotope ratios measured in river water colloids and streambed sediment samples along 426 km of the Sacramento River, California reveal that the influence of lead from the historical mining of massive sulfide deposits in the West Shasta Cu-mining district (at the headwaters of the Sacramento River) is confined to a 60 km stretch of river immediately downstream of that mining region, whereas inputs from past leaded gasoline emissions and historical hydraulic Au-mining in the Sierra Nevadan foothills are the dominant lead sources in the remaining 370 km of the river. Binary mixing calculations suggest that more than 50% of the lead in the Sacramento River outside of the region of influence of the West Shasta Cu-mining district is derived from past depositions of leaded gasoline emissions. This predominance is the first direct documentation of the geographic extent of gasoline lead persistence throughout a large riparian system (>160,000 km 2) and corroborates previous observations based on samples taken at the mouth of the Sacramento River. In addition, new analyses of sediment samples from the hydraulic gold mines of the Sierra Nevada foothills confirm the present-day fluxes into the Sacramento River of contaminant metals derived from historical hydraulic Au-mining that occurred during the latter half of the 19th and early part of the 20th centuries. These fluxes occur predominantly during periods of elevated river discharge associated with heavy winter precipitation in northern California. In the broadest context, the study demonstrates the potential for altered precipitation patterns resulting from climate change to affect the mobility and transport of soil-bound contaminants in the surface environment.

  19. The persistence of lead from past gasoline emissions and mining drainage in a large riparian system: Evidence from lead isotopes in the Sacramento River, California (United States)

    Dunlap, C.E.; Alpers, C.N.; Bouse, R.; Taylor, H.E.; Unruh, D.M.; Flegal, A.R.


    Lead concentrations and isotope ratios measured in river water colloids and streambed sediment samples along 426 km of the Sacramento River, California reveal that the influence of lead from the historical mining of massive sulfide deposits in the West Shasta Cu-mining district (at the headwaters of the Sacramento River) is confined to a 60 km stretch of river immediately downstream of that mining region, whereas inputs from past leaded gasoline emissions and historical hydraulic Au-mining in the Sierra Nevadan foothills are the dominant lead sources in the remaining 370 km of the river. Binary mixing calculations suggest that more than 50% of the lead in the Sacramento River outside of the region of influence of the West Shasta Cu-mining district is derived from past depositions of leaded gasoline emissions. This predominance is the first direct documentation of the geographic extent of gasoline lead persistence throughout a large riparian system (>160,000 km2) and corroborates previous observations based on samples taken at the mouth of the Sacramento River. In addition, new analyses of sediment samples from the hydraulic gold mines of the Sierra Nevada foothills confirm the present-day fluxes into the Sacramento River of contaminant metals derived from historical hydraulic Au-mining that occurred during the latter half of the 19th and early part of the 20th centuries. These fluxes occur predominantly during periods of elevated river discharge associated with heavy winter precipitation in northern California. In the broadest context, the study demonstrates the potential for altered precipitation patterns resulting from climate change to affect the mobility and transport of soil-bound contaminants in the surface environment. ?? 2008 Elsevier Ltd.

  20. Finding clouds, dunes, crevasses and subglacial valleys with surface-texture maps of Antarctica (United States)

    Smith, B. E.; Haran, T. M.; Morin, P. J.; Porter, C. C.; Scambos, T. A.


    An experienced glaciologist can often look at a satellite image of Antarctica and quickly identify glaciers, ice streams, ice shelves, and interstream ridges, and can easily distinguish cloudy from cloud-free images. These distinctions rely on the surface texture of the ice sheet, as revealed by the interaction of sunlight with small slope variations. We present a simple scheme for mapping quantities related to surface texture that are distinct between different ice-sheet terrains. We use the statistics of windowed Fourier transforms of images to map brightness variance in different ranges of scales, and to map the anisotropy of the variations at these scales. Based on the cloud cleared, resolution-enhanced MOA mosaic of Antarctica, we derive roughness and anisotropy estimates at scales between 0.25 and 16 km. While the major distinction between different terrains at these scales is in the variance spectrum, anisotropy is a strong marker of fast-flowing ice. Superimposed on these patterns are aeolean features generated by the interaction of snowfall, wind, and surface topography. In particular, Megadune fields have a distinct spectrum, with a strong spectral peak in the 1-4 km band. This signature is evident in known megadune fields, but can also be seen elsewhere, perhaps because aeolean features in the new areas lack spatial coherence. Based on this, the spatial patterns in accumulation associated with megadunes may be more prevalent that previously identified. MOA texture also shows unusually smooth areas over subglacial valley bottoms throughout Antarctica. This mapping may help in the design of future airborne-radar surveys in areas where the subglacial topography has not previously been measured. Applied to high-resolution imagery from Worldview satellites, at scales between one and 256 meters, our analysis allows easy mapping of crevasse fields, and reveals a widespread, consistent small-scale texture on inland ice associated with sastrugi and meter

  1. Stable water isotopic composition of the Antarctic subglacial Lake Vostok: implications for understanding the lake's hydrology. (United States)

    Ekaykin, Alexey A; Lipenkov, Vladimir Y; Kozachek, Anna V; Vladimirova, Diana O


    We estimated the stable isotopic composition of water from the subglacial Lake Vostok using two different sets of samples: (1) water frozen on the drill bit immediately after the first lake unsealing and (2) water frozen in the borehole after the unsealing and re-drilled one year later. The most reliable values of the water isotopic composition are: -59.0 ± 0.3 ‰ for oxygen-18, -455 ± 1 ‰ for deuterium and 17 ± 1 ‰ for d-excess. This result is also confirmed by the modelling of isotopic transformations in the water which froze in the borehole, and by a laboratory experiment simulating this process. A comparison of the newly obtained water isotopic composition with that of the lake ice (-56.2 ‰ for oxygen-18, -442.4 ‰ for deuterium and 7.2 ‰ for d-excess) leads to the conclusion that the lake ice is very likely formed in isotopic equilibrium with water. In turn, this means that ice is formed by a slow freezing without formation of frazil ice crystals and/or water pockets. This conclusion agrees well with the observed physical and chemical properties of the lake's accreted ice. However, our estimate of the water's isotopic composition is only valid for the upper water layer and may not be representative for the deeper layers of the lake, so further investigations are required.

  2. Semi-automated extraction of longitudinal subglacial bedforms from digital terrain models - Two new methods (United States)

    Jorge, Marco G.; Brennand, Tracy A.


    Relict drumlin and mega-scale glacial lineation (positive relief, longitudinal subglacial bedforms - LSBs) morphometry has been used as a proxy for paleo ice-sheet dynamics. LSB morphometric inventories have relied on manual mapping, which is slow and subjective and thus potentially difficult to reproduce. Automated methods are faster and reproducible, but previous methods for LSB semi-automated mapping have not been highly successful. Here, two new object-based methods for the semi-automated extraction of LSBs (footprints) from digital terrain models are compared in a test area in the Puget Lowland, Washington, USA. As segmentation procedures to create LSB-candidate objects, the normalized closed contour method relies on the contouring of a normalized local relief model addressing LSBs on slopes, and the landform elements mask method relies on the classification of landform elements derived from the digital terrain model. For identifying which LSB-candidate objects correspond to LSBs, both methods use the same LSB operational definition: a ruleset encapsulating expert knowledge, published morphometric data, and the morphometric range of LSBs in the study area. The normalized closed contour method was separately applied to four different local relief models, two computed in moving windows and two hydrology-based. Overall, the normalized closed contour method outperformed the landform elements mask method. The normalized closed contour method performed on a hydrological relief model from a multiple direction flow routing algorithm performed best. For an assessment of its transferability, the normalized closed contour method was evaluated on a second area, the Chautauqua drumlin field, Pennsylvania and New York, USA where it performed better than in the Puget Lowland. A broad comparison to previous methods suggests that the normalized relief closed contour method may be the most capable method to date, but more development is required.

  3. Early drainage mitigates methane and nitrous oxide emissions from organically amended paddy soils

    DEFF Research Database (Denmark)

    Tariq, Azeem; Jensen, Lars Stoumann; de Tourdonnet, Stephane


    Elevated greenhouse gas (GHG) emissions, particularly of methane (CH4) from flooded rice production systems contribute to global warming. Different crop management strategies, such as drainage of paddy soils and climate-smart residue management, are essential in order to mitigate GHG emissions from...... flooded rice systems, but they often conflict with practical management preferences.The aim of this study was to assess the potential of early-season drainage for mitigating CH4 and N2O emissions from soils with and without added organic amendments in relation to native soil organic carbon (SOC). Rice...... to the soils on the basis of an equivalent amount of C added in each organic treatment.The results revealed rapid mineralization of organic C in the double-drained system, resulting in lower total CH4 emissions in treatments under early plus midseason drainage compared to those under midseason drainage only...

  4. A natural rubber drainage tube with antithrombogenic lumen surface. (United States)

    Klöcking, H P; Schunk, W; Merkmann, G; Giessmann, C; Knoll, H; Borgmann, S


    A drainage tube was made by radiation vulcanization of a high polymeric substance based on natural rubber elastomers. Pentosan polysulphate sodium bound to a carrier substance (synthetic type 4A or 13X zeolite) was incorporated in the drainage tube which was then tested for its anticoagulant properties during perfusion with Tris buffer solution, citrated plasma, and blood, resp. The amount of pentosan polysulphate sodium released from the tube walls during perfusion with human citrated plasma in an open circulatory system was sufficient to exert an anticoagulant effect on the streaming plasma. This effect was corroborated by prolonged thrombin times and by unclottability in case of recalcified plasma samples in thrombelastographic studies. The antithrombogenicity test according to Chandler in a closed circulatory system revealed thrombus formation times (TFT) of more than 24 h (control: TFT = 1-3 min in native blood).

  5. Efficiency of lachrymal sac drainage in newborns with dacryocystocele.


    Sakovich V.N.; Serdyuk V.N.; Klopotskaya N.G.; Tarnopol'skaya I.N.


    International audience; The article represents results of treatment of 14 newborns with unilateral dacryocystocele. Patients age was 7.2±0.5 days. In 9 newborns (64.3%) dacryocystocele was complicated with lachrymal sac phlegmon; in 5 children (35.7%) any complications were absent. Drainage of lachrymal sac through the lower lachrymal canaliculus, instillation of antibiotics, systemic antibiotic therapy in case of phlegmon were performed in all the children. Lachrymal sac washing was performe...

  6. Technical problems during percutaneous transhepatic biliary drainage

    Energy Technology Data Exchange (ETDEWEB)

    Weber, J.; Hoever, S.


    Technical problems are repeatedly encountered during percutaneous transhepatic drainage by catheter or endo-prosthesis which are caused by the position, extent and tightness of the stenosis in the biliary ducts. All means of overcoming these problems must be used, otherwise technical failure or complications become inevitable. The methods to be adopted if catheters break and endo-prostheses become displaced or occluded, and for haemorrhage, are described, as well as methods for draining multiple, proximal or intrahepatic stenoses. This is based on an experience with 74 patients on whom 130 drainage procedures have been perforemd (80 catheters, 50 endo-prostheses). All complications and mortality (five patients, 3.8%) were due to problems which could not be solved. Internal biliary drainage by means of an endoprosthesis is markedly superior to catheter drainage. (orig.).

  7. Pressure Jumps during Drainage in Macroporous Soils

    DEFF Research Database (Denmark)

    Soto, Diego; Paradelo Pérez, Marcos; Corral, A


    Tensiometer readings obtained at high resolution during drainage of structured soil columns revealed pressure jumps with long range correlations and burst sequences with a hierarchical structure. The statistical properties of jumps are similar to Haines jumps described in invasion percolation...... processes at pore scale, but they are much larger in amplitude and duration. Pressure jumps can result from transient redistribution of water potential in internal regions of soil and can be triggered during drainage by capillary displacements at the scale of structural pores....

  8. Drainage filter technologies to mitigate site-specific phosphorus losses in agricultural drainage discharge

    DEFF Research Database (Denmark)

    Kjærgaard, Charlotte; Heckrath, Goswin Johann; Canga, Eriona

    Losses of phosphorus (P) in drainage waters contribute an estimated 33% to the total agricultural P load in Denmark. Mitigating agricultural P losses is challenging, as critical P losses comprise only a very small fraction of actual soil P contents and are not directly related to fertilizer P input...... in drainage. The Danish “SUPREME-TECH” project (2010-2016) ( aims at providing the scientific basis for developing cost-effective filter technologies for P in agricultural drainage waters. The project studies different approaches of implementing filter technologies including drainage well...

  9. Unvented single stack sanitary drainage system I

    DEFF Research Database (Denmark)

    Najman, Z.

    This report forms the basis of the preparation of design recommendations. In the observation tables all single results from 147 tests of charging are dispersed on 53 test set-ups. At test set-ups in 1 till 4 floors height discharge pipes with dimensions of 100, 125, and 150 mm were tested...

  10. Drainage system maintenance toward promoting healthy environment

    African Journals Online (AJOL)

    If you would like more information about how to print, save, and work with PDFs, Highwire Press provides a helpful Frequently Asked Questions about PDFs. Alternatively, you can download the PDF file directly to your computer, from where it can be opened using a PDF reader. To download the PDF, click the Download link ...

  11. 46 CFR 171.155 - Drainage of an open boat. (United States)


    ... 46 Shipping 7 2010-10-01 2010-10-01 false Drainage of an open boat. 171.155 Section 171.155... PERTAINING TO VESSELS CARRYING PASSENGERS Drainage of Weather Decks § 171.155 Drainage of an open boat. The deck within the hull of an open boat must drain to the bilge. Overboard drainage of the deck is not...

  12. Percutaneous transhepatic biliary drainage in malignant extrahepatic cholestasis

    Energy Technology Data Exchange (ETDEWEB)

    Hoevels, J.


    The technique of non-surgical percutaneous transhepatic biliary drainage has been improved recently. Combined internal and external drainage of bile was enabled by manipulation of a guide wire and a drainage catheter through the stenosed or obstructed section of the extrahepatic biliary ducts. Experience have been gained concerning internal drainage of bile by percutaneous transhepatic insertion of an endoprosthesis for some years now.

  13. Failures and complications of thoracic drainage

    Directory of Open Access Journals (Sweden)

    Đorđević Ivana


    Full Text Available Background/Aim. Thoracic drainage is a surgical procedure for introducing a drain into the pleural space to drain its contents. Using this method, the pleura is discharged and set to the physiological state which enables the reexpansion of the lungs. The aim of the study was to prove that the use of modern principles and protocols of thoracic drainage significantly reduces the occurrence of failures and complications, rendering the treatment more efficient. Methods. The study included 967 patients treated by thoracic drainage within the period from January 1, 1989 to June 1, 2000. The studied patients were divided into 2 groups: group A of 463 patients treated in the period from January 1, 1989 to December 31, 1994 in whom 386 pleural drainage (83.36% were performed, and group B of 602 patients treated form January 1, 1995 to June 1, 2000 in whom 581 pleural drainage (96.51% were performed. The patients of the group A were drained using the classical standards of thoracic drainage by the general surgeons. The patients of the group B, however, were drained using the modern standards of thoracic drainage by the thoracic surgeons, and the general surgeons trained for this kind of the surgery. Results. The study showed that better results were achieved in the treatment of the patients from the group B. The total incidence of the failures and complications of thoracic drainage decreased from 36.52% (group A to 12.73% (group B. The mean length of hospitalization of the patients without complications in the group A was 19.5 days versus 10 days in the group B. The mean length of the treatment of the patients with failures and complications of the drainage in the group A was 33.5 days versus 17.5 days in the group B. Conclusion. The shorter length of hospitalization and the lower morbidity of the studied patients were considered to be the result of the correct treatment using modern principles of thoracic drainage, a suitable surgical technique, and a

  14. A Laboratory Investigation of the Effects of Subglacial Meltwater Plumes on Submarine Ablation at the Fronts of Tidewater Glaciers (United States)

    Kerr, R. C.; McConnochie, C. D.


    We investigate experimentally the effect of a basal freshwater source on the ablation of a vertical ice wall in salty water. We measure as a function of height the turbulent wall plume velocity, the ablation velocity of the ice, and the temperature at the ice wall. By systematically varying the volume flow rate of the freshwater source, we determine where the turbulent wall plume transitions from a free convection regime (controlled by the distributed buoyancy flux due to dissolution of the ice) to a forced convection regime (controlled by the buoyancy flux Bs of the basal freshwater source). In the forced convection regime, we find that the turbulent plume velocity is uniform with height and is proportional to Bs1/3, the interface temperature is independent of Bs, and the ablation velocity increases with Bs. In the two convection regimes, we find that there are fundamental differences in the wall turbulent plume, the turbulent entrainment coefficient, and the detrainment from the turbulent plume at the top of the wall. Lateral variations in subglacial discharge rates can enable these regimes to occur simultaneously along the front of a tidewater glacier, which will result in subglacial meltwater and submarine meltwater being seen at differing depths in the Greenland fjords.

  15. Lymphatic drainage to the popliteal basin in distal lower extremity malignant melanoma. (United States)

    Menes, Tehillah S; Schachter, Jacob; Steinmetz, Adam P; Hardoff, Ruth; Gutman, Haim


    Hypotheses Melanoma of the distal lower extremity may drain to the popliteal basin. Drainage pathways and retrieval of the popliteal sentinel nodes may affect patient outcome. Retrospective analysis of popliteal involvement in patients with stage IB or higher melanoma, operated on from August 1, 1993, to July 31, 2003. Tertiary referral, university-affiliated medical center. One hundred six melanoma patients who underwent combined lymphoscintigraphy and blue dye-guided sentinel node biopsy, radical popliteal dissection, or both. Incidence and patterns of drainage to popliteal nodes; effect on staging and outcome. Lymphoscintigraphy (n = 8) and physical examination (n = 2) identified 10 cases (9%) of draining to the popliteal basin, with concurrent drainage to the groin. Three distinct drainage patterns were identified, with different popliteal node locations. Seven of 8 popliteal sentinel nodes were retrieved, 1 of which was metastatic with no groin metastasis. Two patients had synchronous palpable popliteal and groin metastases and underwent radical groin and popliteal dissection. All 3 patients with popliteal metastases relapsed early with synchronous systemic and in-transit disease. One of 7 patients with negative sentinel nodes is alive with in-transit disease; all others are disease free. According to this series, the popliteal basin is the site of first drainage in about 9% of patients, with concurrent drainage to the groin. The 3 distinct patterns of drainage to the popliteal region and the presence of isolated popliteal metastases may affect the surgical treatment. Therefore, drainage to popliteal sentinel nodes and the pattern of this drainage should be noted in all distal lower extremity melanomas.

  16. Long term dynamics of nitrate concentrations and leaching losses in tile drainage water from cultivated clayey till at field scale

    DEFF Research Database (Denmark)

    Ernstsen, Vibeke; Olsen, Preben; Rosenbom, Annette Elisabeth


    of application). Furthermore, the standard climatic conditions (e.g. temperature, precipitation) as well as soil moisture and temperature to a depth of approx. 2 meter were measured. Concentrations of nitrate in the drainage and groundwater, recharge of water through the drainage system as well as depth...

  17. A new adjustable glaucoma drainage device. (United States)

    Villamarin, Adan; Roy, Sylvain; Bigler, Stéphane; Stergiopulos, Nikos


    This work is focused on the testing of a new experimental noninvasively adjustable glaucoma drainage device (AGDD) that allows for the control of its outflow resistance to modulate intraocular pressure (IOP) in a customized fashion. Six AGDDs were directly connected to a pressure transducer and a perfusion system continuously delivering saline solution at rate of 2 μL/min. The steady-state pressure was measured and reported as a function of the angular position of the AGDD disk. Ex vivo experiments were conducted on six freshly enucleated rabbit eyes. The IOP was measured, and the flow rate was increased with a syringe pump to simulate elevated IOP associated with glaucoma. After insertion of the implant in the anterior chamber, the position of the disk was sequentially adjusted. The relation between the pressure drop and the angular position of the AGDD disk is nonlinear. The functional range lies between 80° and 130°, which allows for four or five different reproducible adjustment positions. Above 130° the implant is considered to be closed (no outflow), and below 80° it is considered to be open (minimum resistance to flow). The resistance to outflow of the experimental AGDD can be adjusted to keep IOP in the desired physiological range. This feature could be useful for addressing the risk of hypotony in the early postoperative stages and could provide a means to achieve optimal IOP under a wide range of postoperative conditions.

  18. [The biological aftereffects of preoperative and palliative percutaneous biliary drainage]. (United States)

    Arévalo, A; Hebrero, J; Arconada, J A; Fernández, M; Elexpuru, J I; Escudero, B; Lalinde, J; Pinillos, E


    Biological repercussions in 78 patients with malignant obstructive jaundice in whom percutaneous biliary drainage was performed, are reported. In 37 cases drainage was done during operation while 41 were palliative. Biochemistry, proteinogram, hematological studies, renal function and immunology were assessed 15.7 +/- 3.4 days postoperatively and 25.2 +/- 4.7 days in palliative drainage. Results show a significant improvement of all parameters, more important in preoperative drainages especially in those combining percutaneous and internal drainage techniques.

  19. Impact of a localized source of subglacial discharge on the heat flux and submarine melting of a tidewater glacier : A laboratory study

    NARCIS (Netherlands)

    Cenedese, Claudia; Gatto, V.M.


    Idealized laboratory experiments have been conducted in a two-layer stratified fluid to investigate the leading-order dynamics that control submarine melting and meltwater export near a vertical ice-ocean interface as a function of subglacial discharge. In summer, the discharge of surface runoff

  20. Evidence for Subglacial Deformation and Deposition during a Complete Advance-Stagnation Cycle of Kötlujökull, Iceland – A Case Study

    DEFF Research Database (Denmark)


    deformation and deposition from dynamically active ice, (4) subglacial deposition from stagnant ice and (5) supraglacial re-deposition in dead-ice environment during de-icing. This complete sedimentary sequence represents a single glacier advance-stagnation cycle. The melt-out till displays moderate...

  1. Diversity of culturable bacteria recovered from Pico Bolívar's glacial and subglacial environments, at 4950 m, in Venezuelan tropical Andes. (United States)

    Rondón, Johnma; Gómez, Wileidy; Ball, María M; Melfo, Alejandra; Rengifo, Marcos; Balcázar, Wilvis; Dávila-Vera, Delsy; Balza-Quintero, Alirio; Mendoza-Briceño, Rosa Virginia; Yarzábal, Luis Andrés


    Even though tropical glaciers are retreating rapidly and many will disappear in the next few years, their microbial diversity remains to be studied in depth. In this paper we report on the biodiversity of the culturable fraction of bacteria colonizing Pico Bolívar's glacier ice and subglacial meltwaters, at ∼4950 m in the Venezuelan Andean Mountains. Microbial cells of diverse morphologies and exhibiting uncompromised membranes were present at densities ranging from 1.5 × 10(4) to 4.7 × 10(4) cells/mL in glacier ice and from 4.1 × 10(5) to 9.6 × 10(5) cells/mL in subglacial meltwater. Of 89 pure isolates recovered from the samples, the majority were eurypsychrophilic or stenopsychrophilic, according to their temperature range of growth. Following analysis of their 16S rDNA nucleotidic sequence, 54 pure isolates were assigned to 23 phylotypes distributed within 4 different phyla or classes: Beta- and Gammaproteobacteria, Actinobacteria, and Bacteroidetes. Actinobacteria dominated the culturable fraction of glacier ice samples, whereas Proteobacteria were dominant in subglacial meltwater samples. Chloramphenicol and ampicillin resistance was exhibited by 73.07% and 65.38%, respectively, of the subglacial isolates, and nearly 35% of them were multiresistant. Considering the fast rate at which tropical glaciers are melting, this study confirms the urgent need to study the microbial communities immured in such environments.

  2. Adjustment of rainfall estimates from weather radars using in-situ stormwater drainage sensors

    DEFF Research Database (Denmark)

    Ahm, Malte

    The topic of this Ph.D. thesis is adjustment of weather radar rainfall measurements for urban drainage applications by the use of in-situ stormwater runoff measurements. It is possible to obtain the high spatiotemporal resolution rainfall data desired for advanced distributed urban drainage...... applications by the use of weather radars. Rainfall data representing the spatiotemporal distribution is a necessity for accurate modelling and real-time control of distributed urban drainage systems. Weather radar measurements are indirect measurements of the rainfall in the atmosphere, which poses some...... challenges for using the data in urban drainage applications. There are discrepancies between radar-rainfall measured in the atmosphere and the “true” rainfall at ground level. Consequently, radar-rainfall estimates are usually adjusted to rainfall observations at ground level from rain gauges. When radar...


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    Innocent A. Ugbong


    Full Text Available In order to achieve the task of formulating an optimal drainage model for the Calabar area, the Calabar drainage system was studied using some cartographic techniques to analyze its surface run-off and channel characteristics so as to determine how floods are generated. A morphological analysis was done, using detailed contour maps prepared for the study area. The “Blue line” and “contour crenulations” methods were used to recreate the expected run-off channels or drainage networks under natural non-urbanized conditions. A drainage structure with 6 major basins and 73 sub-basins was discovered. Existing storm drains were constructed without regards to this natural structure and so floods were generated.

  4. Percutaneous drainage and ablation of orbital dermoid cysts. (United States)

    Golden, Richard P; Shiels, William E; Cahill, Kenneth V; Rogers, Gary L


    Vision-threatening intraorbital dermoid cysts have traditionally been treated by complete surgical resection. Such radical surgical intervention may pose serious risks to both vision acuity and cosmesis. We describe a novel, minimally invasive approach for the treatment of orbital dermoid cysts. This is an interventional retrospective case series. Two patients (17 and 4 years) presented with large intraorbital dermoid cysts. The first patient had a dumbbell-shaped lesion involving the temporalis fossa and superotemporal orbit. The second patient had a large, superior intraorbital lesion. Both patients presented with visual disturbance, globe displacement, and eyelid ptosis. A series of techniques were developed and implemented for percutaneous access, drainage, and catheter-based ablation (dual drug technique) of both orbital dermoid cysts. Initial access was gained with a 14-gauge angiocatheter needle system, followed by serial emulsification and drainage of the cyst contents. A 5-French catheter was coaxially placed for fluoroscopic contrast cyst definition and subsequent dual drug chemical ablation (sodium tetradecyl sulfate and ethanol). Suction drainage was maintained for 24 hours following ablation. Radiological and clinical evaluation demonstrated complete resolution of the dermoid cysts with no recurrence at 12-month follow-up in the first patient and 3 months in the second patient. Cosmetic results were excellent. Patients reported no pain and there were no neurologic, oculomotor, infectious, hemorrhagic, or other complications. Minimally invasive percutaneous drainage and ablation appears to be a promising treatment for large orbital dermoid cysts which would otherwise require extensive surgery to excise. Collaboration of an ophthalmologist and interventional radiologist is essential for evaluation, treatment, and follow-up.

  5. Experimental analysis of drainage and water storage of litter layers (United States)

    Guevara-Escobar, A.; Gonzalez-Sosa, E.; Ramos-Salinas, M.; Hernandez-Delgado, G. D.


    Leaf litter overlying forested floors are important for erosion control and slope stability, but also reduces pasture growth in silvopastoral systems. Little information exists regarding the value of percolation and storage capacity parameters for litter layers. These estimates are needed for modelling better management practices for leaf litter. Therefore, this work measured the effect of four rainfall intensities: 9.8, 30.2, 40.4 and 70.9 mm h-1 on the hydrological response of layers of three materials: recently senesced poplar leaves, fresh grass and woodchips. Maximum storage (Cmax), defined as the detention of water immediately before rainfall cessation, increased with rainfall intensity. The magnitude of the increment was 0.2 mm between the lowest and highest rainfall intensities. Mean values of Cmax were: 1.27, 1.51, 1.67 and 1.65 mm for poplar leaves; 0.63 0.77, 0.73 and 0.76 for fresh grass and; 1.64, 2.23, 2.21 and 2.16 for woodchips. Drainage parameters were: 9.9, 8.8 and 2.2 mm-1 for poplar, grass and woodchips layers. An underlying soil matrix influenced the drainage flow from poplar leaf layers producing pseudo-Hortonian overland flow, but this occurred only when the rainfall intensity was 40.4 and 70.9 mm h-1 and accounted for 0.4 and 0.8‰ of total drainage. On the other hand, the presence of a poplar leaf layer had a damping effect on the drainage rate from the underlying soil matrix, particularly at intermediate rainfall intensities: 30.2 or 40.4 mm h-1.

  6. Effect of Cerebrospinal Fluid Drainage on Brain Tissue Oxygenation in Traumatic Brain Injury. (United States)

    Akbik, Omar S; Krasberg, Mark; Nemoto, Edwin M; Yonas, Howard


    The effectiveness of cerebrospinal fluid (CSF) drainage in lowering high intracranial pressure (ICP) is well established in severe traumatic brain injury (TBI). Recently, however, the use of external ventricular drains (EVDs) and ICP monitors in TBI has come under question. The aim of this retrospective study was to investigate the effect of CSF drainage on brain tissue oxygenation (PbtO2). Using a multi-modality monitoring system, we continuously monitored PbtO2 and parenchymal ICP during CSF drainage events via a ventriculostomy in 40 patients with severe TBI. Measurements were time-locked continuous recordings on a Component Neuromonitoring System in a neuroscience intensive care unit. We further selected for therapeutic CSF drainage events initiated at ICP values above 25 mm Hg and analyzed the 4-min periods before and after drainage for the physiologic variables ICP, cerebral perfusion pressure (CPP), and PbtO2. We retrospectively identified 204 CSF drainage events for ICP EVD-opening values greater than 25 mm Hg in 23 patients. During the 4 min of opened EVD, ICP decreased by 5.7 ± 0.6 mm Hg, CPP increased by 4.1 ± 1.2 mm Hg, and PbtO2 increased by 1.15 ± 0.26 mm Hg. ICP, CPP, and PbtO2 all improved with CSF drainage at ICP EVD-opening values above 25 mm Hg. Although the average PbtO2 changes were small, a clinically significant change in PbtO2 of 5 mm Hg or greater occurred in 12% of CSF drainage events, which was correlated with larger decreases in ICP, displaying a complex relationship between ICP and PbtO2 that warrants further studies.

  7. Percutaneous epidural drainage through a burr hole

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    Priscila M Falsarella


    Full Text Available Intracranial extradural collection may cause an increase in intracranial pressure, requiring rapid emergency treatment to reduce morbidity and mortality. We described an alternative CT-guided percutaneous access for extradural collection drainage. We report a case of a patient with previous craniectomy for meningioma ressection who presented to the Emergency Department with symptoms of intracranial hypertension. Brains CT showed a extradural collection with subfalcine herniation. After multidisciplinary discussion a CT-guided percutaneous drainage through previous burr hole was performed. The patient was discharged after 36 hours of admission, without further symptoms. We describe a safe and effective alternative percutaneous access for extradural collection drainage in patients with previous burr hole.


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    Full Text Available Altogether 327 valleys and their 314 cross-sectional profiles were analyzed on Mars, including width, depth, length, eroded volume, drainage and spatial density, as well as the network structure.According to this systematic analysis, five possible drainage network types were identified such as (a small valleys, (b integrated small valleys, (c individual, medium-sized valleys, (d unconfined,anastomosing outflow valleys, and (e confined outflow valleys. Measuring their various morphometric parameters, these five networks differ from each other in terms of parameters of the eroded volume, drainage density and depth values. This classification is more detailed than those described in the literature previously and correlated to several numerical parameters for the first time.These different types were probably formed during different periods of the evolution of Mars, and sprung from differently localized water sources, and they could be correlated to similar fluvialnetwork types from the Earth.

  9. An Innovative Approach for Drainage Network Sizing

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    Luca Cozzolino


    Full Text Available In this paper, a procedure for the optimal design of rural drainage networks is presented and demonstrated. The suggested approach, exploring the potentialities offered by heuristic methods for the solution of complex optimization problems, is based on the use of a Genetic Algorithm (GA, coupled with a steady and uniform flow hydraulic module. In particular, this work has focused: on one hand, on the problems of a technical nature posed by the correct sizing of a drainage network; on the other hand, on the possibility to use a simple but nevertheless efficient GA to reach the minimal cost solution very quickly. The suitability of the approach is tested with reference to small and large scale drainage networks, already considered in the literature.

  10. Glaucoma Drainage Device Erosion Following Ptosis Surgery. (United States)

    Bae, Steven S; Campbell, Robert J


    To highlight the potential risk of glaucoma drainage device erosion following ptosis surgery. Case report. A 71-year-old man underwent uncomplicated superotemporal Ahmed glaucoma valve implantation in the left eye in 2008. Approximately 8 years later, the patient underwent bilateral ptosis repair, which successfully raised the upper eyelid position. Three months postoperatively, the patient's glaucoma drainage implant tube eroded through the corneal graft tissue and overlying conjunctiva to become exposed. A graft revision surgery was successfully performed with no further complications. Caution and conservative lid elevation may be warranted when performing ptosis repair in patients with a glaucoma drainage implant, and patients with a glaucoma implant undergoing ptosis surgery should be followed closely for signs of tube erosion.

  11. Dynamics of a vertical turbulent plume in a stratification typical of Greenland fjords: an idealized model of subglacial discharge (United States)

    Stenberg, Erik; Ezhova, Ekaterina; Cenedese, Claudia; Brandt, Luca


    We the report results of large eddy simulations of a turbulent buoyant plume in a configuration providing an idealized model of subglacial discharge from a submarine glacier in stratifications typical of Greenland Fjords. We neglect a horizontal momentum of the plume and assume that its influence on the plume dynamics is small and important only close to the source. Moreover, idealized models have considered the plume adjacent to the glacier as a half-conical plume (e.g., [1]). Thus, to compare the results for such plume with the classical plume theory, developed for free plumes entraining ambient fluid from all directions, it is convenient to add the second half-conical part and consider a free plume with double the total discharge as a model. Given the estimate of the total subglacial discharge for Helheim Glacier in Sermilik Fjord [2], we perform simulations with double the total discharge in order to investigate the dynamics of the flow in typical winter and summer stratifications in Greenland fjords [3]. The plume is discharged from a round source of various diameters. In winter, when the stratification is similar to an idealised two-layers case, turbulent entrainment and generation of internal waves by the plume top are in agreement with the theoretical and numerical results obtained for turbulent jets in a two-layer stratification. In summer, instead, the stratification is more complex and turbulent entrainment is significantly reduced. The subsurface layer in summer is characterized by a strong density gradient and the oscillating plume generates non-linear internal waves which are able to mix this layer even if the plume does not penetrate to the surface. The classical theory for the integral parameters of a turbulent plume in a homogeneous fluid gives accurate predictions of the plume parameters in the weakly stratified lower layer up to the pycnocline. [1] Mankoff, K. D., F. Straneo, C. Cenedese, S. B. Das, C. D. Richards, and H. Singh, 2016: Structure

  12. Hydrologic Impact Of Subsurface Drainage Of Agricultural Fields (United States)

    Naz, B. S.; Johannsen, C. J.; Bowling, L. C.


    Although subsurface drainage has benefited agricultural productions in many regions of the U.S., there are also concerns about the potential impacts of these systems on watershed hydrology and water quality. This study was focused on tile lines identification and hydrologic response of subsurface drainage systems for the Agronomy Center for Research and Education (ACRE), West Lafayette, Indiana and the Southeastern Purdue Agriculture Center (SEPAC) in southeastern, Indiana. The purpose of the study was to develop and evaluate a remote sensing methodology for automatic detection of tile lines from aerial photographs and to evaluate the Distributed Hydrology Soil-Vegetation Model (DHSVM) to analyze the hydrologic response of tile drained fields. A step-wise approach was developed to first use different image enhancement techniques to increase the visual distinction of tile lines from other details in the image. A new classification model was developed to identify locations of subsurface tiles using a decision tree classifier which compares the multiple data sets such as enhanced image data, land use class, soil drainage class, hydrologic group and surface slope. Accuracy assessment of the predicted tile map was done by comparing the locations of tile drains with existing historic maps and ground-truth data. The overall performance of decision tree classifier model coupled with other pre- and post- classification methods shows that this model can be a very effective tool in identifying tile lines from aerial photographs over large areas of land. Once the tile map was created, the DHSVM was applied to ACRE and SEPAC respectively to see the hydrological impact of the subsurface drainage network. Observed data for 3-years (1998-2000) at ACRE and for 6-years (1993-1998) at SEPAC were used to calibrate and validate the model. The model was simulated for three scenarios: 1) baseline scenario (no tiles), 2) with known tile lines and 3) with tile lines created through

  13. Conventional And Non-Conventional Elements For Urban Drainage Catchment Stormwater (United States)

    Rodriguez Diaz, Hector Alfonso; Calderon, Leidy Johanna Franco


    The main objective of urban drainage system is to allow the safe passage of pedestrians and vehicles quickly evacuating the runoff to prevent flooding. However, development of cities has altered the natural water cycle and providing wide range of contaminants to surface water streams receiving rain from the urban system. For these reasons we have developed unconvention-urban al rainwater systems unconventional rainwater, in accordance with sustainable development, called Sustainable Urban Drainage Systems (SUDS). Considering that the urban drainage system begins with the collection on the site of origin of runoff, in this article the study of conventional and unconventional elements for capturing rainwater arises, establishing the general criteria for selection and design and the classification of SUDS.

  14. The Role of Geochemical Modeling in Predicting Quality Evolution of Acid Mine Drainage

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    Andrea Šlesárová


    Full Text Available In recent years the massive reduction of raw materials production brings a wide scale of problems. Among the most frequent exposes of mining activities belong besides old spoil heaps and sludge lagoons, also the drainage of acidic and highly mineralized mine waters known as “the Acid Mine Drainage” (thereinafter AMD from old mine workings. The acid mine drainage presents to the surrounding environment a massive problem. These waters are toxic to the plant and animal life, including fishes and aquatic insects. The primary control of the drainage pH and the metal content is the exposure of sulphide minerals to weathering, the availability of atmospheric oxygen, and the sensitivity of non-sulphide minerals to buffer acidity. A geochemical modeling software is increasingly used to solve evolution of the complex chemical systems such as the interaction of acid mine drainage with wall rocks, migration of AMD components. Beyond the better computer facilities it allows to study of thermodynamic properties substances and to enlarge thermodynamic databases. A model is a simplified version of reality based on its observation and experiments. A goal of the modeling process is the tendency to better understand processes taking place inside of the system, the attempt to assume the system’s behaviour in the future or to predict the effect of changed conditions in the system’s environment on the system itself.

  15. Solid Waste in Drainage Network of Rio do Meio Watershed, Florianópolis/SC

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    Taiana Gava


    Full Text Available The urban drainage network is among the main pollution transport load factors. Researches on the identification of solid waste transported in the drainage network have been considered the allow evaluation of its impact. In this paper we analyze the main characteristics that influences the presence of solid wastes in the drainage network of the Rio do Meio basin, Florianópolis/SC. A metal net was installed in selected river section and monitored after each rain event. The results showed about 0.27 kg/ha.year of waste are carried in the drainage network. The majority being composed of plastics and building materials. Through the analysis of the data, it was possible to verify the presence of waste in the drainage network is due to poor packaging and to the lack of sweeping in some parts of the basin. It was also found that the total precipitation is directly proportional to the appearance of solid waste. It was concluded that the lack of an integrated management between the components of sanitary system leave unnoticed simple structural measures that ultimately decrease the amount of solid waste in the drainage basin, and that could eliminate this source of pollution.

  16. Reconstruction of North American drainage basins and river discharge since the Last Glacial Maximum

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    A. D. Wickert


    Full Text Available Over the last glacial cycle, ice sheets and the resultant glacial isostatic adjustment (GIA rearranged river systems. As these riverine threads that tied the ice sheets to the sea were stretched, severed, and restructured, they also shrank and swelled with the pulse of meltwater inputs and time-varying drainage basin areas, and sometimes delivered enough meltwater to the oceans in the right places to influence global climate. Here I present a general method to compute past river flow paths, drainage basin geometries, and river discharges, by combining models of past ice sheets, glacial isostatic adjustment, and climate. The result is a time series of synthetic paleohydrographs and drainage basin maps from the Last Glacial Maximum to present for nine major drainage basins – the Mississippi, Rio Grande, Colorado, Columbia, Mackenzie, Hudson Bay, Saint Lawrence, Hudson, and Susquehanna/Chesapeake Bay. These are based on five published reconstructions of the North American ice sheets. I compare these maps with drainage reconstructions and discharge histories based on a review of observational evidence, including river deposits and terraces, isotopic records, mineral provenance markers, glacial moraine histories, and evidence of ice stream and tunnel valley flow directions. The sharp boundaries of the reconstructed past drainage basins complement the flexurally smoothed GIA signal that is more often used to validate ice-sheet reconstructions, and provide a complementary framework to reduce nonuniqueness in model reconstructions of the North American ice-sheet complex.

  17. Heat sources for glacial ice melt in a West Greenland tidewater outlet glacier fjord: The role of subglacial freshwater discharge

    DEFF Research Database (Denmark)

    Bendtsen, Jørgen; Mortensen, John; Lennert, Kunuk


    The melting of tidewater outlet glaciers from the Greenland Ice Sheet contributes significantly to global sea level rise. Accelerated mass loss is related to melt-processes in front of calving glaciers, yet the role of ocean heat transports is poorly understood. Here we present the first direct...... measurements from a subglacial plume in front of a calving tidewater outlet glacier. Surface salinity in the plume corresponded to a meltwater content of 7 %, which is indicative of significant entrainment of warm bottom water and, according to plume model calculations, significant ice melt. Energy balance...... of the area near the glacier showed that ice melt was mainly due to ocean heat transport and that direct plume-associated melt was only important in periods with high meltwater discharge rates of ~100 m3 s−1. Ocean mixing outside of the plume area was thus the primary heat source for melting glacier ice....