WorldWideScience

Sample records for monitoring subsurface flow

  1. Remote Monitoring of Subsurface Flow Conditions in Rivers

    Science.gov (United States)

    2013-09-30

    measured by the ADV. The colored stars represent the run mean flow magnitudes obtained by the 3 methods: DPIV, OF and SAS. TKE Dissipation The...Mech., vol. 77, 531-560. Korchoka Y. M. (1968). Investigation of the dune movement of sediments on the Polomet’ River. Sov. Hydrol. 541-559. McKenna

  2. Opportunities and challenges for the application of SP measurements to monitor subsurface flow (Invited)

    Science.gov (United States)

    Jackson, M.; Vinogradov, J.; MacAllister, D.; Butler, A. P.; Leinov, E.; Zhang, J.

    2013-12-01

    Measurements of self-potential (SP) have been proposed or applied to monitor flow in the shallow subsurface in numerous settings, including volcanoes, earthquake zones, geothermal fields and hydrocarbon reservoirs, to detect leaks from dams, tanks and embankments, and to characterize groundwater flow and hydraulic properties. To interpret the measurements, it is generally assumed that the SP is dominated by the streaming potential, arising from the drag of excess electrical charge in the diffuse part of the electrical double layer at the mineral-fluid interfaces. The constitutive equation relating electrical current density j to the driving forces ▽V and ▽P is then j = -σ▽V -σC▽P=-σ▽V + Qv (1) where V is the streaming potential, P is the water pressure, σ is the saturated rock conductivity, v is the Darcy velocity, C is the streaming potential coupling coefficient, and Q is the excess charge transported by the flow. Equation (1) shows that there is a close relationship between flow properties of interest, such as the pressure gradient or Darcy velocity, and the streaming potential component of the SP. Hence SP measurements are an attractive method to monitor subsurface flow. However, the problem with interpreting the measurements is that both C and Q can vary over orders of magnitude, in response to variations in pore-water salinity, temperature, rock texture, and the presence of NAPLs in the pore-space. Moreover, additional current sources may be present if there are gradients in concentration or temperature, arising from differential rates of ion migration down gradient (diffusion potentials), and because of charge exclusion from the pore-space (exclusion potentials). In general, these additional current sources are neglected. This talk suggests a potential new opportunity for the application of SP measurements to monitor subsurface flow, in which the signal of interest arises from salinity rather than pressure gradients. Saline intrusion into

  3. Time-Lapse Monitoring of Subsurface Fluid Flow using Parsimonious Seismic Interferometry

    KAUST Repository

    Hanafy, Sherif

    2017-04-21

    A typical small-scale seismic survey (such as 240 shot gathers) takes at least 16 working hours to be completed, which is a major obstacle in case of time-lapse monitoring experiments. This is especially true if the subject that needs to be monitored is rapidly changing. In this work, we will discuss how to decrease the recording time from 16 working hours to less than one hour of recording. Here, the virtual data has the same accuracy as the conventional data. We validate the efficacy of parsimonious seismic interferometry with the time-lapse mentoring idea with field examples, where we were able to record 30 different data sets within a 2-hour period. The recorded data are then processed to generate 30 snapshots that shows the spread of water from the ground surface down to a few meters.

  4. Solar subsurface flows from local helioseismology

    Science.gov (United States)

    Zhao, Junwei; Chen, Ruizhu

    2016-07-01

    In this article, we review recent progresses in subsurface flows obtained from two local helioseismology methods: time-distance helioseismology and ring-diagram analysis. We review results in the following four topics: flows beneath sunspots and active regions, supergranular subsurface flows, shallow meridional flow and its variations with solar cycles, and meridional circulation in the deep solar interior. Despite recent advancements in methodology, modeling, and observations, many questions are still to be answered and a few topics remain controversial. More efforts, especially in numerical modeling and accurate interpretation of acoustic wave travel-time measurements, are needed to improve the derivations of subsurface flows.

  5. Monitoring subsurface CO2 storage

    NARCIS (Netherlands)

    Winthaegen, P.; Arts, R.; Schroot, B.M.

    2005-01-01

    An overview is given of various currently applied monitoring techniques for CO2 storage. Techniques are subdivided in correspondence to their applicability for monitoring three distinct realms. These are: - the atmosphere and the near-surface; - the overburden (including faults and wells); - the

  6. Radionuclide Sensors for Subsurface Water Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Timothy DeVol

    2006-06-30

    Contamination of the subsurface by radionuclides is a persistent and vexing problem for the Department of Energy. These radionuclides must be measured in field studies and monitoed in the long term when they cannot be removed. However, no radionuclide sensors existed for groundwater monitoring prior to this team's research under the EMSP program Detection of a and b decays from radionuclides in water is difficult due to their short ranges in condensed media.

  7. Instruments for subsurface monitoring of geothermal subsidence

    Energy Technology Data Exchange (ETDEWEB)

    O' Rourke, J.E.; Ranson, B.B.

    1979-07-01

    The requirements for a subsurface geothermal subsidence instrument were reviewed. Available instruments for monitoring subsurface displacements, both vertical and horizontal, were studied and the most capable instruments identified. Techniques and materials for improving existing or developing new instruments were evaluated. Elements of sensor and signal technology with potential for high temperature monitoring of subsidence were identified. Drawing from these studies, methods to adapt production wells for monitoring were proposed and several new instrumentation systems were conceptually designed. Finally, four instrumentation systems were selected for future development. These systems are: triple sensor induction sensor probe (with casing collar markers); triple sensor gamma ray detector probe (with radioactive markers); triple sensor reed switch probe (with magnet markers); and triple sensor oscillator-type magnet detector probe (with magnet markers). All are designed for use in well casing incorporating slip couplings or bellows sections, although the gamma ray detector probe may also be used in unlined holes. These systems all measure vertical moement. Instruments to measure horizontal displacement due to geothermal subsidence were studied and the required instrument performance was judged to be beyond the state-of-the-art. Thus, no conceptual designs for instruments to monitor horizontal movement are included.

  8. Low temperature monitoring system for subsurface barriers

    Science.gov (United States)

    Vinegar, Harold J.; McKinzie, II. Billy John

    2009-08-18

    A system for monitoring temperature of a subsurface low temperature zone is described. The system includes a plurality of freeze wells configured to form the low temperature zone, one or more lasers, and a fiber optic cable coupled to at least one laser. A portion of the fiber optic cable is positioned in at least one freeze well. At least one laser is configured to transmit light pulses into a first end of the fiber optic cable. An analyzer is coupled to the fiber optic cable. The analyzer is configured to receive return signals from the light pulses.

  9. Air-water flow in subsurface systems

    Science.gov (United States)

    Hansen, A.; Mishra, P.

    2013-12-01

    Groundwater traces its roots to tackle challenges of safe and reliable drinking water and food production. When the groundwater level rises, air pressure in the unsaturated Vadose zone increases, forcing air to escape from the ground surface. Abnormally high and low subsurface air pressure can be generated when the groundwater system, rainfall, and sea level fluctuation are favorably combined [Jiao and Li, 2004]. Through this process, contamination in the form of volatile gases may diffuse from the ground surface into residential areas, or possibly move into groundwater from industrial waste sites. It is therefore crucial to understand the combined effects of air-water flow in groundwater system. Here we investigate theoretically and experimentally the effects of air and water flow in groundwater system.

  10. Paracetamol removal in subsurface flow constructed wetlands

    Science.gov (United States)

    Ranieri, Ezio; Verlicchi, Paola; Young, Thomas M.

    2011-07-01

    SummaryIn this study two pilot scale Horizontal Subsurface Flow Constructed Wetlands (HSFCWs) near Lecce, Italy, planted with different macrophytes ( Phragmites australis and Typha latifolia) and an unplanted control were assessed for their effectiveness in removing paracetamol. Residence time distributions (RTDs) for the two beds indicated that the Typha bed was characterized by a void volume fraction (porosity) of 0.16 and exhibited more ideal plug flow behavior (Pe = 29.7) than the Phragmites bed (Pe = 26.7), which had similar porosity. The measured hydraulic residence times in the planted beds were 35.8 and 36.7 h when the flow was equal to 1 m 3/d. The Phragmites bed exhibited a range of paracetamol removals from 51.7% for a Hydraulic Loading Rate (HLR) of 240 mm/d to 87% with 120 mm/d HLR and 99.9% with 30 mm/d. The Typha bed showed a similar behavior with percentages of removal slightly lower, ranging from 46.7% (HLR of 240 mm/d) to >99.9% (hydraulic loading rate of 30 mm/d). At the same HLR values the unplanted bed removed between 51.3% and 97.6% of the paracetamol. In all three treatments the paracetamol removal was higher with flow of 1 m 3/d and an area of approx. 7.5 m 2 (half bed) than in the case of flow equal to 0.5 m 3/d with a surface treatment of approx. 3.75 m 2. A first order model for paracetamol removal was evaluated and half lives of 5.16 to 10.2 h were obtained.

  11. Planetary heat flow from shallow subsurface measurements: Mars

    Science.gov (United States)

    Cornwall, Marc; Hagermann, Axel

    2016-10-01

    Planetary heat flow probes measure heat flow (depth-resolved temperature and thermal conductivity) to provide insight into the internal state of a planet. The probes have been utilized extensively on Earth, twice on the Moon, and once on the Surface of comet 67P-CG. Mars is an important target for heat flow measurement as heat flow is a critical parameter in Martian thermal history models. Earlier studies indicate that Martian planetary heat flow can be accessed at 5 m below the surface in dry regolith monitored over at least one Martian year. A one Martian year monitoring period is necessary because, in the shallow subsurface, heat flow from the interior is superposed with time varying heat flow contributions, primarily due to insolation. Given that a heat flow probe may not achieve its target depth or monitoring period, this study investigates how the depth (2-5 m), duration (0-1 Martian year) and quality of measurements influence the accuracy of planetary heat flow. An inverse model is used to show that, in the preceding scenarios, the accuracy of planetary heat flow directly estimated from depth-dependent thermal conductivity with 10-20% precision errors, temperatures with 50-100 mK precision errors and modelling uncertainties up to 500 mK, can, on average, be improved by a factor of 27 with optimization to 13%. Accuracies increase with sensor penetration depth and regolith monitoring period. Heat flow optimized from instantaneous measurements or those with the shortest regolith monitoring periods have increased accuracy where the frequency and amplitude of the temperature variation are lowest. The inverse model is based on the Function Specification Inversion method. This study demonstrates that a solution subspace can be identified within a space of uncertainties modelled for the temperature measurements and planetary heat flow: the subspace is defined by a constant log-ratio of their respective standard deviations. Optimized heat flow estimates display

  12. Monitoring the subsurface with quasi-static deformation

    Energy Technology Data Exchange (ETDEWEB)

    Sneider, Roel; Spetzler, Hartmut

    2013-09-06

    This project consisted of three sub-projects that are all aimed at monitoring the subsurface with geophysical methods. The objectives of these sub-projects are: to investigate the use of seismic waves for remote monitoring of temperature changes in the Yucca Mountain nuclear repository; to investigate the use of measured changes in the tidal tilt as a diagnostic for the infiltration of fluids in the subsurface; and to extract the electrostatic response from dynamic field fluctuations.

  13. A field study of colloid transport in surface and subsurface flows

    Science.gov (United States)

    Zhang, Wei; Tang, Xiang-Yu; Xian, Qing-Song; Weisbrod, Noam; Yang, Jae E.; Wang, Hong-Lan

    2016-11-01

    Colloids have been recognized to enhance the migration of strongly-sorbing contaminants. However, few field investigations have examined combined colloid transport via surface runoff and subsurface flows. In a headwater catchment of the upper Yangtze River, a 6 m (L) by 4 m (W) sloping (6°) farmland plot was built by cement walls to form no-flow side boundaries. The plot was monitored in the summer of 2014 for the release and transport of natural colloids via surface runoff and subsurface flows (i.e., the interflow from the soil-mudrock interface and fracture flow from the mudrock-sandstone interface) in response to rain events. The water sources of the subsurface flows were apportioned to individual rain events using a two end-member model (i.e., mobile pre-event soil water extracted by a suction-cup sampler vs. rainwater (event water)) based on δ18O measurements. For rain events with high preceding soil moisture, mobile pre-event soil water was the main contributor (generally >60%) to the fracture flow. The colloid concentration in the surface runoff was 1-2 orders of magnitude higher than that in the subsurface flows. The lowest colloid concentration was found in the subsurface interflow, which was probably the result of pore-scale colloid straining mechanisms. The rainfall intensity and its temporal variation govern the dynamics of the colloid concentrations in both surface runoff and subsurface flows. The duration of the antecedent dry period affected not only the relative contributions of the rainwater and the mobile pre-event soil water to the subsurface flows but also the peak colloid concentration, particularly in the fracture flow. The rain period because their transport in association with colloids may occur rapidly over long distances via both surface runoff and subsurface flows with rainfall.

  14. Simulation and validation of concentrated subsurface lateral flow paths in an agricultural landscape

    Directory of Open Access Journals (Sweden)

    Q. Zhu

    2009-08-01

    Full Text Available The importance of soil water flow paths to the transport of nutrients and contaminants has long been recognized. However, effective means of detecting concentrated subsurface flow paths in a large landscape are still lacking. The flow direction and accumulation algorithm based on single-direction flow algorithm (D8 in GIS hydrologic modeling is a cost-effective way to simulate potential concentrated flow paths over a large area once relevant data are collected. This study tested the D8 algorithm for simulating concentrated lateral flow paths at three interfaces in soil profiles in a 19.5-ha agricultural landscape in central Pennsylvania, USA. These interfaces were (1 the interface between surface plowed layers of Ap1 and Ap2 horizons, (2 the interface with subsoil water-restricting clay layer where clay content increased to over 40%, and (3 the soil-bedrock interface. The simulated flow paths were validated through soil hydrologic monitoring, geophysical surveys, and observable soil morphological features. The results confirmed that concentrated subsurface lateral flow occurred at the interfaces with the clay layer and the underlying bedrock. At these two interfaces, the soils on the simulated flow paths were closer to saturation and showed more temporally unstable moisture dynamics than those off the simulated flow paths. Apparent electrical conductivity in the soil on the simulated flow paths was elevated and temporally unstable as compared to those outside the simulated paths. The soil cores collected from the simulated flow paths showed significantly higher Mn content at these interfaces than those away from the simulated paths. These results suggest that (1 the D8 algorithm is useful in simulating possible concentrated subsurface lateral flow paths if used with appropriate threshold value of contributing area and sufficiently detailed digital elevation model (DEM; (2 repeated electromagnetic surveys can reflect the temporal change of soil

  15. Hillslope characteristics as controls of subsurface flow variability

    Directory of Open Access Journals (Sweden)

    S. Bachmair

    2012-06-01

    Full Text Available Hillslope hydrological dynamics, particularly subsurface flow (SSF, are highly variable and complex. A profound understanding of factors controlling this variability is needed. Therefore we investigated the relationship between variability of shallow water table dynamics and various hillslope characteristics. We ask whether measurable hillslope properties explain patterns of subsurface flow variability. To approach this question shallow water table dynamics of three adjacent large-scale hillslopes were monitored with high spatial and temporal resolution over 18 months. The hillslopes are similar in terms of topography and parent material, but different in vegetation cover (grassland, coniferous forest, and mixed forest. We expect vegetation to be an important driver of water table dynamics at our study site, especially given the minor differences in topography. Various hillslope properties were determined in the field and via GIS analysis: common topography descriptors, well depth, soil properties via slug tests, and several vegetation parameters. Response variables characterizing the water table response per well were calculated for different temporal scales (entire time series, seasonal scale, event scale. Partial correlation analysis and a Random Forest machine learning approach were carried out to assess the explainability of SSF variability by measurable hillslope characteristics. We found a complex interplay of predictors, yet soil properties and topography showed the highest single explanatory power. Surprisingly, vegetation characteristics played a minor role. Solely throughfall and canopy cover exerted a slightly stronger control, especially in summer. Most importantly, the examined hillslope characteristics explained only a small proportion of the observed SSF variability. Consequently there must be additional important drivers not represented by current measurement techniques of the hillslope configuration (e.g. bedrock properties

  16. Hillslope characteristics as controls of subsurface flow variability

    Science.gov (United States)

    Bachmair, S.; Weiler, M.

    2012-10-01

    Hillslope hydrological dynamics, particularly subsurface flow (SSF), are highly variable and complex. A profound understanding of factors controlling this variability is needed. Therefore we investigated the relationship between variability of shallow water table dynamics and various hillslope characteristics. We ask whether measurable hillslope properties explain patterns of subsurface flow variability. To approach this question, shallow water table dynamics of three adjacent large-scale hillslopes were monitored with high spatial and temporal resolution over 18 months. The hillslopes are similar in terms of topography and parent material, but different in vegetation cover (grassland, coniferous forest, and mixed forest). We expect vegetation to be an important driver of water table dynamics at our study site, especially given the minor differences in topography. Various hillslope properties were determined in the field and via GIS analysis: common topography descriptors, well depth, soil properties via slug tests, and several vegetation parameters. Response variables characterizing the water table response per well were calculated for different temporal scales (entire time series, seasonal scale, event scale). Partial correlation analysis and a Random Forest machine learning approach were carried out to assess the explainability of SSF variability by measurable hillslope characteristics. We found a complex interplay of predictors, yet soil properties and topography showed the highest single explanatory power. Surprisingly, vegetation characteristics played a minor role. Solely throughfall and canopy cover exerted a slightly stronger control, especially in summer. Most importantly, the examined hillslope characteristics explained only a small proportion of the observed SSF variability. Consequently there must be additional important drivers not represented by current measurement techniques of the hillslope configuration (e.g. bedrock properties, preferential

  17. Hillslope characteristics as controls of subsurface flow variability

    Directory of Open Access Journals (Sweden)

    S. Bachmair

    2012-10-01

    Full Text Available Hillslope hydrological dynamics, particularly subsurface flow (SSF, are highly variable and complex. A profound understanding of factors controlling this variability is needed. Therefore we investigated the relationship between variability of shallow water table dynamics and various hillslope characteristics. We ask whether measurable hillslope properties explain patterns of subsurface flow variability. To approach this question, shallow water table dynamics of three adjacent large-scale hillslopes were monitored with high spatial and temporal resolution over 18 months. The hillslopes are similar in terms of topography and parent material, but different in vegetation cover (grassland, coniferous forest, and mixed forest. We expect vegetation to be an important driver of water table dynamics at our study site, especially given the minor differences in topography. Various hillslope properties were determined in the field and via GIS analysis: common topography descriptors, well depth, soil properties via slug tests, and several vegetation parameters. Response variables characterizing the water table response per well were calculated for different temporal scales (entire time series, seasonal scale, event scale. Partial correlation analysis and a Random Forest machine learning approach were carried out to assess the explainability of SSF variability by measurable hillslope characteristics. We found a complex interplay of predictors, yet soil properties and topography showed the highest single explanatory power. Surprisingly, vegetation characteristics played a minor role. Solely throughfall and canopy cover exerted a slightly stronger control, especially in summer. Most importantly, the examined hillslope characteristics explained only a small proportion of the observed SSF variability. Consequently there must be additional important drivers not represented by current measurement techniques of the hillslope configuration (e.g. bedrock properties

  18. Scale invariance of subsurface flow patterns and its limitation

    Science.gov (United States)

    Hergarten, S.; Winkler, G.; Birk, S.

    2016-05-01

    Preferential flow patterns in the subsurface are of great importance for the availability and the quality of water resources. However, knowledge of their spatial structure is still behind their importance, so that understanding the nature of preferential flow patterns is a major issue in subsurface hydrology. Comparing the statistics of river catchment sizes and spring discharges, we found that the morphology of preferential subsurface flow patterns is probably scale invariant and similar to that of dendritic river networks. This result is not limited to karstic aquifers where the occurrence of dendritic structures has been known at least qualitatively for a long time. The scale invariance even seems to be independent of the lithology of the aquifer. However, scale invariance of river patterns seems to be only limited by the continental scale, while scale invariance of subsurface flow patterns breaks down at much smaller scales. The upper limit of scale invariance in subsurface flow patterns is highly variable. We found a range from thousands of square kilometers for limestone aquifers down to less than 1 km2 in the weathered zone and debris accumulations of crystalline rocks.

  19. Relationship Between Storm Hydrograph Components and Subsurface Flow Processes in a Hilly Headwater Basin, Toyota, Japan

    Science.gov (United States)

    Tsujimura, M.; Asai, K.; Takei, R.

    2001-05-01

    Temporal and spatial distribution of tracer elements and subsurface flow processes were investigated to study relationship between storm hydrograph components and behavior of subsurface water in a headwater catchment of Toyota Hill, Aichi prefecture, central Japan. The catchment has an area of 0.857 ha with an altitude of 60 to 100 m, and is underlain by granite. The soil depth revealed by sounding test ranges from 0.5 to 4.0 m. Rain, stream, soil and ground waters were sampled once in a week, and the stream water was sampled at 5 to 60 minute intervals during rainstorms. The pressure head of subsurface water was monitored using tensiometers and piezometers nests, and the stream flow was monitored using V-notch weir. The stable isotopic ratios of deuterium and oxygen 18 and inorganic ion concentrations were determined on all water samples. The oxygen 18 isotopic ratio in stream water decreased with rainfall during the rainstorms. The ratio of event water component to the total runoff water at the peak discharge ranged from 16 to 92 %, and the event water ratio correlated with the peak discharge rate and rainfall intensity. The tesiometric data showed that the shallow subsurface water with low isotopic ratios at the lower slope discharged directly to the stream during the heavy rainstorms. The shallow subsurface flow at the lower slope and overland flow on the raiparian zone contributed much to the stream water chemistry during heavy rainstorms.

  20. Integrated Surface/subsurface flow modeling in PFLOTRAN

    Energy Technology Data Exchange (ETDEWEB)

    Painter, Scott L [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    Understanding soil water, groundwater, and shallow surface water dynamics as an integrated hydrological system is critical for understanding the Earth’s critical zone, the thin outer layer at our planet’s surface where vegetation, soil, rock, and gases interact to regulate the environment. Computational tools that take this view of soil moisture and shallow surface flows as a single integrated system are typically referred to as integrated surface/subsurface hydrology models. We extend the open-source, highly parallel, subsurface flow and reactive transport simulator PFLOTRAN to accommodate surface flows. In contrast to most previous implementations, we do not represent a distinct surface system. Instead, the vertical gradient in hydraulic head at the land surface is neglected, which allows the surface flow system to be eliminated and incorporated directly into the subsurface system. This tight coupling approach leads to a robust capability and also greatly simplifies implementation in existing subsurface simulators such as PFLOTRAN. Successful comparisons to independent numerical solutions build confidence in the approximation and implementation. Example simulations of the Walker Branch and East Fork Poplar Creek watersheds near Oak Ridge, Tennessee demonstrate the robustness of the approach in geometrically complex applications. The lack of a robust integrated surface/subsurface hydrology capability had been a barrier to PFLOTRAN’s use in critical zone studies. This work addresses that capability gap, thus enabling PFLOTRAN as a community platform for building integrated models of the critical zone.

  1. Adaptive Multiscale Finite Element Method for Subsurface Flow Simulation

    NARCIS (Netherlands)

    Van Esch, J.M.

    2010-01-01

    Natural geological formations generally show multiscale structural and functional heterogeneity evolving over many orders of magnitude in space and time. In subsurface hydrological simulations the geological model focuses on the structural hierarchy of physical sub units and the flow model addresses

  2. Control and optimzation of sub-surface flow

    NARCIS (Netherlands)

    Jansen, J.D.

    2013-01-01

    Controlling the flow of fluids (e.g. water, oil, natural gas or CO2) in subsurface porous media is a technical process with many mathematical challenges. The underlying physics can be described with coupled nearly-elliptic and nearly-hyperbolic nonlinear partial differential equations, which require

  3. Adaptive Multiscale Finite Element Method for Subsurface Flow Simulation

    NARCIS (Netherlands)

    Van Esch, J.M.

    2010-01-01

    Natural geological formations generally show multiscale structural and functional heterogeneity evolving over many orders of magnitude in space and time. In subsurface hydrological simulations the geological model focuses on the structural hierarchy of physical sub units and the flow model addresses

  4. Treatment of swine wastewater with subsurface-flow constructed ...

    African Journals Online (AJOL)

    Treatment of swine wastewater with subsurface-flow constructed wetlands in Yucatán, ... 57 and 79% for total nitrogen, 63 and 75% for ammonium nitrogen, 70 and ... However, vegetated beds slightly improved water quality when compared to ...

  5. Controlling Subsurface Fractures and Fluid Flow: A Basic Research Agenda

    Energy Technology Data Exchange (ETDEWEB)

    Pyrak-Nolte, Laura J [Purdue Univ., West Lafayette, IN (United States); DePaolo, Donald J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Pietraß, Tanja [USDOE Office of Science, Washington, DC (United States)

    2015-05-22

    From beneath the surface of the earth, we currently obtain about 80-percent of the energy our nation consumes each year. In the future we have the potential to generate billions of watts of electrical power from clean, green, geothermal energy sources. Our planet’s subsurface can also serve as a reservoir for storing energy produced from intermittent sources such as wind and solar, and it could provide safe, long-term storage of excess carbon dioxide, energy waste products and other hazardous materials. However, it is impossible to underestimate the complexities of the subsurface world. These complexities challenge our ability to acquire the scientific knowledge needed for the efficient and safe exploitation of its resources. To more effectively harness subsurface resources while mitigating the impacts of developing and using these resources, the U.S. Department of Energy established SubTER – the Subsurface Technology and Engineering RD&D Crosscut team. This DOE multi-office team engaged scientists and engineers from the national laboratories to assess and make recommendations for improving energy-related subsurface engineering. The SubTER team produced a plan with the overall objective of “adaptive control of subsurface fractures and fluid flow.”This plan revolved around four core technological pillars—Intelligent Wellbore Systems that sustain the integrity of the wellbore environment; Subsurface Stress and Induced Seismicity programs that guide and optimize sustainable energy strategies while reducing the risks associated with subsurface injections; Permeability Manipulation studies that improve methods of enhancing, impeding and eliminating fluid flow; and New Subsurface Signals that transform our ability to see into and characterize subsurface systems. The SubTER team developed an extensive R&D plan for advancing technologies within these four core pillars and also identified several areas where new technologies would require additional basic research

  6. Evaluation of nutrient removal efficiency and microbial enzyme activity in a baffled subsurface-flow constructed wetland system

    Science.gov (United States)

    Lihua Cui; Ying Ouyang; Wenjie Gu; Weozhi Yang; Qiaoling. Xu

    2013-01-01

    In this study, the enzyme activities and their relationships to domestic wastewater purification are investigated in four different types of subsurface-flow constructed wetlands (CWs), namely the traditional horizontal subsurface-flow, horizontal baffled subsurface-flow, vertical baffled subsurface-flow, and composite baffled subsurface-flow CWs. Results showed that...

  7. Organized Subsurface Flows near Active Regions

    Science.gov (United States)

    Haber, D. A.; Hindman, B. W.; Toomre, J.; Thompson, M. J.

    2004-04-01

    Local helioseismic techniques, such as ring analysis and time-distance helioseismology, have already shown that large-scale flows near the surface converge towards major active regions. Ring analysis has further demonstrated that at greater depths some active regions exhibit strong outflows. A critique leveled at the ring-analysis results is that the Regularized Least Squares (RLS) inversion kernels on which they are based have negative sidelobes near the surface. Such sidelobes could result in a surface inflow being misidentified as a diverging outflow at depth. In this paper we show that the Optimally Located Averages (OLA) inversion technique, which produces kernels without significant sidelobes, generates flows markedly similar to the RLS results. Active regions are universally zones of convergence near the surface, while large complexes evince strong outflows deeper down.

  8. Subsurface magnetic field and flow structure of simulated sunspots

    CERN Document Server

    Rempel, Matthias

    2011-01-01

    We present a series of numerical sunspot models addressing the subsurface field and flow structure in up to 16 Mm deep domains covering up to 2 days of temporal evolution. Changes in the photospheric appearance of the sunspots are driven by subsurface flows in several Mm depth. Most of magnetic field is pushed into a downflow vertex of the subsurface convection pattern, while some fraction of the flux separates from the main trunk of the spot. Flux separation in deeper layers is accompanied in the photosphere with light bridge formation in the early stages and formation of pores separating from the spot at later stages. Over a time scale of less than a day we see the development of a large scale flow pattern surrounding the sunspots, which is dominated by a radial outflow reaching about 50% of the convective rms velocity in amplitude. Several components of the large scale flow are found to be independent from the presence of a penumbra and the associated Evershed flow. While the simulated sunspots lead to blo...

  9. Online monitoring of food processes using subsurface laser scattering

    DEFF Research Database (Denmark)

    Carstensen, Jens Michael; Møller, Flemming

    Online monitoring of physical parameters during food production is not a trivial task, but promising results can often be obtained with Subsurface Laser Scattering (SLS). The first SLS instruments are on the market today, and studies are needed to asses the potential of the technology. SLS can...... monitor particle changes and gelation formation in a fast and non-invasive manner during production of most food products. SLS is correlated to classical particle sizing parameters, i.e. size, number of light scatters and refractive index, as well as sensoric parameters like mouthfeel. The background...

  10. Advanced Algebraic Multigrid Solvers for Subsurface Flow Simulation

    KAUST Repository

    Chen, Meng-Huo

    2015-09-13

    In this research we are particularly interested in extending the robustness of multigrid solvers to encounter complex systems related to subsurface reservoir applications for flow problems in porous media. In many cases, the step for solving the pressure filed in subsurface flow simulation becomes a bottleneck for the performance of the simulator. For solving large sparse linear system arising from MPFA discretization, we choose multigrid methods as the linear solver. The possible difficulties and issues will be addressed and the corresponding remedies will be studied. As the multigrid methods are used as the linear solver, the simulator can be parallelized (although not trivial) and the high-resolution simulation become feasible, the ultimately goal which we desire to achieve.

  11. Subsurface flow constructed wetlands for the treatment of domestic wastewater

    OpenAIRE

    Saeed, Tanveer Ferdous

    2017-01-01

    This thesis describes in detail the background, methods, results, and conclusions of a three-year PhD research project - “subsurface flow constructed wetlands for the treatment of domestic wastewater”, which was undertaken at Monash University between April 2008 and December 2010. The overall objective of the research was to discover the efficiencies of key pollutant removals (organics, nutrients, solids, and coliforms), when a medium-strength wastewater is treated in different types of subsu...

  12. Characterization, Modeling, Monitoring and Remediation of Radionuclides in the Subsurface

    Science.gov (United States)

    Nicholson, T. J.; Cady, R.

    2009-12-01

    NRC sponsors research to identify and assess characterization, modeling, monitoring and remediation methods used to quantify and evaluate radionuclide release and migration in the subsurface. The need for and selection of remediation methods is based on a dose assessment to determine compliance with regulatory criteria. If remediation is warranted, the choice of remediation methods is based upon site- and source-characterization data. This data is integrated in a Conceptual Site Model (CSM). The assumptions and parameterization of the CSM are tested using a program of field tests and confirmatory monitoring. In particular, the features, events and processes in the unsaturated zone where many leaks and spills originate need characterization and confirmatory monitoring. The choice of the remediation method, if warranted, is based upon the confirmed CSM and the monitoring baseline. Remediation strategies being considered are: in situ bioremediation; pump, treat, monitor and release; monitored natural attenuation. Successful remediation strategies include monitoring programs to determine their efficacy. This monitoring is coupled to performance assessment models using performance indicators (PIs). These PIs provide a measurable indication of remediation performance, and are derived from analysis of the CSM and the hydrologic, chemical and microbial functions of the chosen remediation method. Case studies illustrate these observations and provide detailed examples of CSMs and PIs.

  13. Controlling Subsurface Fractures and Fluid Flow: A Basic Research Agenda

    Energy Technology Data Exchange (ETDEWEB)

    Pyrak-Nolte, Laura J [Purdue Univ., West Lafayette, IN (United States); DePaolo, Donald J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Pietraß, Tanja [USDOE Office of Science, Washington, DC (United States)

    2015-05-22

    From beneath the surface of the earth, we currently obtain about 80-percent of the energy our nation consumes each year. In the future we have the potential to generate billions of watts of electrical power from clean, green, geothermal energy sources. Our planet’s subsurface can also serve as a reservoir for storing energy produced from intermittent sources such as wind and solar, and it could provide safe, long-term storage of excess carbon dioxide, energy waste products and other hazardous materials. However, it is impossible to underestimate the complexities of the subsurface world. These complexities challenge our ability to acquire the scientific knowledge needed for the efficient and safe exploitation of its resources. To more effectively harness subsurface resources while mitigating the impacts of developing and using these resources, the U.S. Department of Energy established SubTER – the Subsurface Technology and Engineering RD&D Crosscut team. This DOE multi-office team engaged scientists and engineers from the national laboratories to assess and make recommendations for improving energy-related subsurface engineering. The SubTER team produced a plan with the overall objective of “adaptive control of subsurface fractures and fluid flow.”This plan revolved around four core technological pillars—Intelligent Wellbore Systems that sustain the integrity of the wellbore environment; Subsurface Stress and Induced Seismicity programs that guide and optimize sustainable energy strategies while reducing the risks associated with subsurface injections; Permeability Manipulation studies that improve methods of enhancing, impeding and eliminating fluid flow; and New Subsurface Signals that transform our ability to see into and characterize subsurface systems. The SubTER team developed an extensive R&D plan for advancing technologies within these four core pillars and also identified several areas where new technologies would require additional basic research

  14. Remote Real-Time Monitoring of Subsurface Landfill Gas Migration

    Directory of Open Access Journals (Sweden)

    Alan F. Smeaton

    2011-06-01

    Full Text Available The cost of monitoring greenhouse gas emissions from landfill sites is of major concern for regulatory authorities. The current monitoring procedure is recognised as labour intensive, requiring agency inspectors to physically travel to perimeter borehole wells in rough terrain and manually measure gas concentration levels with expensive hand-held instrumentation. In this article we present a cost-effective and efficient system for remotely monitoring landfill subsurface migration of methane and carbon dioxide concentration levels. Based purely on an autonomous sensing architecture, the proposed sensing platform was capable of performing complex analytical measurements in situ and successfully communicating the data remotely to a cloud database. A web tool was developed to present the sensed data to relevant stakeholders. We report our experiences in deploying such an approach in the field over a period of approximately 16 months.

  15. Subsurface Monitoring of CO2 Sequestration - A Review and Look Forward

    Science.gov (United States)

    Daley, T. M.

    2012-12-01

    The injection of CO2 into subsurface formations is at least 50 years old with large-scale utilization of CO2 for enhanced oil recovery (CO2-EOR) beginning in the 1970s. Early monitoring efforts had limited measurements in available boreholes. With growing interest in CO2 sequestration beginning in the 1990's, along with growth in geophysical reservoir monitoring, small to mid-size sequestration monitoring projects began to appear. The overall goals of a subsurface monitoring plan are to provide measurement of CO2 induced changes in subsurface properties at a range of spatial and temporal scales. The range of spatial scales allows tracking of the location and saturation of the plume with varying detail, while finer temporal sampling (up to continuous) allows better understanding of dynamic processes (e.g. multi-phase flow) and constraining of reservoir models. Early monitoring of small scale pilots associated with CO2-EOR (e.g., the McElroy field and the Lost Hills field), developed many of the methodologies including tomographic imaging and multi-physics measurements. Large (reservoir) scale sequestration monitoring began with the Sleipner and Weyburn projects. Typically, large scale monitoring, such as 4D surface seismic, has limited temporal sampling due to costs. Smaller scale pilots can allow more frequent measurements as either individual time-lapse 'snapshots' or as continuous monitoring. Pilot monitoring examples include the Frio, Nagaoka and Otway pilots using repeated well logging, crosswell imaging, vertical seismic profiles and CASSM (continuous active-source seismic monitoring). For saline reservoir sequestration projects, there is typically integration of characterization and monitoring, since the sites are not pre-characterized resource developments (oil or gas), which reinforces the need for multi-scale measurements. As we move beyond pilot sites, we need to quantify CO2 plume and reservoir properties (e.g. pressure) over large scales, while still

  16. Characterisation of microbial biocoenosis in vertical subsurface flow constructed wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Tietz, Alexandra [Institute of Sanitary Engineering and Water Pollution Control, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna (Austria)]. E-mail: alexandra.tietz@boku.ac.at; Kirschner, Alexander [Clinical Institute for Hygiene and Medical Microbiology, Department for Water Hygiene - Medical University of Vienna, Kinderspitalgasse 15, A-1090 Vienna (Austria); Langergraber, Guenter [Institute of Sanitary Engineering and Water Pollution Control, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna (Austria); Sleytr, Kirsten [Institute of Sanitary Engineering and Water Pollution Control, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna (Austria); Haberl, Raimund [Institute of Sanitary Engineering and Water Pollution Control, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna (Austria)

    2007-07-15

    In this study a quantitative description of the microbial biocoenosis in subsurface vertical flow constructed wetlands fed with municipal wastewater was carried out. Three different methods (substrate induced respiration, ATP measurement and fumigation-extraction) were applied to measure the microbial biomass at different depths of planted and unplanted systems. Additionally, bacterial biomass was determined by epifluorescence microscopy and productivity was measured via {sup 14}C leucine incorporation into bacterial biomass. All methods showed that > 50% of microbial biomass and bacterial activity could be found in the first cm and about 95% in the first 10 cm of the filter layer. Bacterial biomass in the first 10 cm of the filter body accounted only for 16-19% of the total microbial biomass. Whether fungi or methodical uncertainties are mainly responsible for the difference between microbial and bacterial biomass remains to be examined. A comparison between the purification performance of planted and unplanted pilot-scale subsurface vertical flow constructed wetlands (PSCWs) showed no significant difference with the exception of the reduction of enterococci. The microbial biomass in all depths of the filter body was also not different in planted and unplanted systems. Compared with data from soils the microbial biomass in the PSCWs was high, although the specific surface area of the used sandy filter material available for biofilm growth was lower, especially in the beginning of the set-up of the PSCWs, due to missing clay and silt fraction.

  17. The migration and monitoring of viscous NAPLs (coal tar and creosote) in the subsurface

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, R. [Intera Engineering Ltd., Heidelberg, ON (Canada)

    2009-07-01

    The high viscosity of nonaqueous phase liquids (NAPLs) such as creosote and coal tar complicates efforts to monitor their mobility at contaminated sites. Viscous NAPLs can remain mobile for many decades after their application as a wood preservative, or after the closure of the facilities in which they were generated. NAPL-wet pathways in the subsurface can also lead to errors in residual saturation measurements. This abstract discussed issues related to creeping flow and the low seepage rates that are not accounted for using traditional measuring methods. Examples of creeping flow and the monitoring techniques used to assess it were presented for sites in British Columbia and Florida. The drainage of viscous NAPLs during water table declines was also considered, and a case study of a coal tar-removal procedures using polymer surfactant flooding was presented.

  18. 2012 Groundwater Monitoring Report Central Nevada Test Area, Subsurface Corrective Action Unit 443

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-04-01

    The Central Nevada Test Area was the site of a 0.2- to 1-megaton underground nuclear test in 1968. The surface of the site has been closed, but the subsurface is still in the corrective action process. The corrective action alternative selected for the site was monitoring with institutional controls. Annual sampling and hydraulic head monitoring are conducted as part of the subsurface corrective action strategy. The site is currently in the fourth year of the 5-year proof-of-concept period that is intended to validate the compliance boundary. Analytical results from the 2012 monitoring are consistent with those of previous years. Tritium remains at levels below the laboratory minimum detectable concentration in all wells in the monitoring network. Samples collected from reentry well UC-1-P-2SR, which is not in the monitoring network but was sampled as part of supplemental activities conducted during the 2012 monitoring, indicate concentrations of tritium that are consistent with previous sampling results. This well was drilled into the chimney shortly after the detonation, and water levels continue to rise, demonstrating the very low permeability of the volcanic rocks. Water level data from new wells MV-4 and MV-5 and recompleted well HTH-1RC indicate that hydraulic heads are still recovering from installation and testing. Data from wells MV-4 and MV-5 also indicate that head levels have not yet recovered from the 2011 sampling event during which several thousand gallons of water were purged. It has been recommended that a low-flow sampling method be adopted for these wells to allow head levels to recover to steady-state conditions. Despite the lack of steady-state groundwater conditions, hydraulic head data collected from alluvial wells installed in 2009 continue to support the conceptual model that the southeast-bounding graben fault acts as a barrier to groundwater flow at the site.

  19. Understanding the rapidity of subsurface storm flow response from a fracture-oriented shallow vadose through a new perspective

    Science.gov (United States)

    Zhao, Peng; Zhao, Pei; Liang, Chuan; Li, Tianyang; Zhou, Baojia

    2017-01-01

    Velocity and celerity in hydrologic systems are controlled by different mechanisms. Efforts were made through joint sample collection and the use of hydrographs and tracers to understand the rapidity of the subsurface flow response to rainstorms on hourly time scales. Three deep subsurface flows during four natural rainstorm events were monitored. The results show that (1) deeper discharge was observed early in responding rainfall events and yielded a high hydrograph amplitude; (2) a ratio index, k, reflecting the dynamic change of the rainfall perturbation intensity in subsurface flow, might reveal inner causal relationships between the flow index and the tracer signal index. Most values of k were larger than 1 at the perturbation stage but approximated 1 at the no-perturbation stage; and (3) for statistical analysis of tracer signals in subsurface flows, the total standard deviation was 17.2, 11.9, 7.4 and 3.5 at perturbation stages and 4.4, 2.5, 1.1, and 0.95 at the non-perturbation stage for observed events. These events were 3-7 times higher in the former rather than the later, reflecting that the variation of tracer signals primarily occurred under rainfall perturbation. Thus, we affirmed that the dynamic features of rainfall have a key effect on rapid processes because, besides the gravity, mechanical waves originating from dynamic rainfall features are another driving factor for conversion between different types of rainfall mechanical energy. A conceptual model for pressure wave propagation was proposed, in which virtual subsurface flow processes in a heterogeneous vadose zone under rainfall are analogous to the water hammer phenomenon in complex conduit systems. Such an analogy can allow pressure in a shallow vadose to increase and decrease and directly influence the velocity and celerity of the flow reflecting a mechanism for rapid subsurface hydrologic response processes in the shallow vadose zone.

  20. Geoelectrical monitoring of simulated subsurface leakage to support high-hazard nuclear decommissioning at the Sellafield Site, UK

    Energy Technology Data Exchange (ETDEWEB)

    Kuras, Oliver, E-mail: oku@bgs.ac.uk [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Wilkinson, Paul B.; Meldrum, Philip I.; Oxby, Lucy S. [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Uhlemann, Sebastian [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); ETH-Swiss Federal Institute of Technology, Institute of Geophysics, Sonneggstr. 5, 8092 Zurich (Switzerland); Chambers, Jonathan E. [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Binley, Andrew [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Graham, James [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria CA20 1PG (United Kingdom); Smith, Nicholas T. [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria CA20 1PG (United Kingdom); School of Earth, Atmospheric and Environmental Sciences, Williamson Building, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Atherton, Nick [Sellafield Ltd, Albion Square, Swingpump Lane, Whitehaven CA28 7NE (United Kingdom)

    2016-10-01

    A full-scale field experiment applying 4D (3D time-lapse) cross-borehole Electrical Resistivity Tomography (ERT) to the monitoring of simulated subsurface leakage was undertaken at a legacy nuclear waste silo at the Sellafield Site, UK. The experiment constituted the first application of geoelectrical monitoring in support of decommissioning work at a UK nuclear licensed site. Images of resistivity changes occurring since a baseline date prior to the simulated leaks revealed likely preferential pathways of silo liquor simulant flow in the vadose zone and upper groundwater system. Geophysical evidence was found to be compatible with historic contamination detected in permeable facies in sediment cores retrieved from the ERT boreholes. Results indicate that laterally discontinuous till units forming localized hydraulic barriers substantially affect flow patterns and contaminant transport in the shallow subsurface at Sellafield. We conclude that only geophysical imaging of the kind presented here has the potential to provide the detailed spatial and temporal information at the (sub-)meter scale needed to reduce the uncertainty in models of subsurface processes at nuclear sites. - Graphical abstract: 3D fractional resistivity change (resistivity change Δρ divided by baseline resistivity ρ{sub 0}) image showing results of Stage 1 silo liquor simulant injection. The black line delineates the preferential flow path; green cylinders show regions of historic contamination found in sediment cores from ERT boreholes. - Highlights: • 4D geoelectrical monitoring at Sellafield detected and tracked simulated silo leaks. • ERT revealed likely pathways of silo liquor simulant flow in the subsurface. • The method can reduce uncertainty in subsurface process models at nuclear sites. • Has been applied in this form at a UK nuclear licensed site for the first time • Study demonstrates value of 4D geophysics for nuclear decommissioning.

  1. Development of stream-subsurface flow module in sub-daily simulation of Escherichia coli using SWAT

    Science.gov (United States)

    Kim, Minjeong; Boithias, Laurie; Cho, Kyung Hwa; Silvera, Norbert; Thammahacksa, Chanthamousone; Latsachack, Keooudone; Rochelle-Newall, Emma; Sengtaheuanghoung, Oloth; Pierret, Alain; Pachepsky, Yakov A.; Ribolzi, Olivier

    2017-04-01

    Water contaminated with pathogenic bacteria poses a large threat to public health, especially in the rural areas in the tropics where sanitation and drinking water facilities are often lacking. Several studies have used the Soil and Water Assessment Tool (SWAT) to predict the export of in-stream bacteria at a watershed-scale. However, SWAT is limited to in-stream processes, such as die-off, resuspension and, deposition; and it is usually implemented on a daily time step using the SCS Curve Number method, making it difficult to explore the dynamic fate and transport of bacteria during short but intense events such as flash floods in tropical humid montane headwaters. To address these issues, this study implemented SWAT on an hourly time step using the Green-Ampt infiltration method, and tested the effects of subsurface flow (LATQ+GWQ in SWAT) on bacterial dynamics. We applied the modified SWAT model to the 60-ha Houay Pano catchment in Northern Laos, using sub-daily rainfall and discharge measurements, electric conductivity-derived fractions of overland and subsurface flows, suspended sediments concentrations, and the number of fecal indicator organism Escherichia coli monitored at the catchment outlet from 2011 to 2013. We also took into account land use change by delineating the watershed with the 3-year composite land use map. The results show that low subsurface flow of less than 1 mm recovered the underestimation of E. coli numbers during the dry season, while high subsurface flow caused an overestimation during the wet season. We also found that it is more reasonable to apply the stream-subsurface flow interaction to simulate low in-stream bacteria counts. Using fecal bacteria to identify and understand the possible interactions between overland and subsurface flows may well also provide some insight into the fate of other bacteria, such as those involved in biogeochemical fluxes both in-stream and in the adjacent soils and hyporheic zones.

  2. A Cloud Based Framework For Monitoring And Predicting Subsurface System Behaviour

    Science.gov (United States)

    Versteeg, R. J.; Rodzianko, A.; Johnson, D. V.; Soltanian, M. R.; Dwivedi, D.; Dafflon, B.; Tran, A. P.; Versteeg, O. J.

    2015-12-01

    Subsurface system behavior is driven and controlled by the interplay of physical, chemical, and biological processes which occur at multiple temporal and spatial scales. Capabilities to monitor, understand and predict this behavior in an effective and timely manner are needed for both scientific purposes and for effective subsurface system management. Such capabilities require three elements: Models, Data and an enabling cyberinfrastructure, which allow users to use these models and data in an effective manner. Under a DOE Office of Science funded STTR award Subsurface Insights and LBNL have designed and implemented a cloud based predictive assimilation framework (PAF) which automatically ingests, controls quality and stores heterogeneous physical and chemical subsurface data and processes these data using different inversion and modeling codes to provide information on the current state and evolution of subsurface systems. PAF is implemented as a modular cloud based software application with five components: (1) data acquisition, (2) data management, (3) data assimilation and processing, (4) visualization and result delivery and (5) orchestration. Serverside PAF uses ZF2 (a PHP web application framework) and Python and both open source (ODM2) and in house developed data models. Clientside PAF uses CSS and JS to allow for interactive data visualization and analysis. Client side modularity (which allows for a responsive interface) of the system is achieved by implementing each core capability of PAF (such as data visualization, user configuration and control, electrical geophysical monitoring and email/SMS alerts on data streams) as a SPA (Single Page Application). One of the recent enhancements is the full integration of a number of flow and mass transport and parameter estimation codes (e.g., MODFLOW, MT3DMS, PHT3D, TOUGH, PFLOTRAN) in this framework. This integration allows for autonomous and user controlled modeling of hydrological and geochemical processes. In

  3. Removal of nutrients from septic tank effluent with baffle subsurface-flow constructed wetlands

    Science.gov (United States)

    Lihu Cui; Ying Ouyang; Weizhi Yang; Zhujian Huang; Qiaoling Xu; Guangwei Yu

    2015-01-01

    Three new baffle flow constructed wetlands (CWs), namely the baffle horizontal flow CW (Z1), baffle vertical flow CW (Z2) and baffle hybrid flow CW (Z3), along with one traditional horizontal subsurface flow CW (Z4) were designed to test the removal efficiency of nitrogen (N) and phosphorus (P) from the septic tank effluent under varying hydraulic retention times (HRTs...

  4. Sub-Surface Oil Monitoring Cruise (GU1002, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Objectives were to evaluate ability of acoustic echosounder measurements to detect and localize a sub-surface plume of oil or related hydrocarbons released from the...

  5. Effective sensing approach for assessment and monitoring of in-situ biodegradation in a subsurface environment

    Science.gov (United States)

    Li, Dong X.

    1999-02-01

    Rapid assessment and monitoring of biological conditions in a subsurface environment is becoming more and more important as bioremediation approaches become widely used in environmental cleanup. Remediation monitoring is also more challenging for in-situ remedial approaches, such as bioventing, biosparging, or passive bioremediation, where conventional 'inlet' and 'outlet' monitoring can no longer be applied. A sensing approach using subsurface chemical sensors offers a cost- effective alternative for remediation monitoring. Additional benefits of deploying subsurface sensors include continuous and unattended measurement with minimum disturbance to the subsurface condition. In a series of field studies, an electrochemical oxygen sensor, a non-dispersive infrared (NDIR) carbon dioxide sensor, and two hydrocarbons sensors were employed for monitoring in-situ bioremediation of petroleum hydrocarbon contaminated soils. Biodegradation rates were effectively measured through an in-situ respiration measurement using subsurface oxygen and carbon dioxide sensors. The high sensitivity of the carbon dioxide sensor to small change in the concentration enables rapid respiration measurements. Subsurface hydrocarbon sensors offer a means to monitor the progress of remediation and the migration of contaminant vapors during the remediation. The chemical sensors tested are clearly cost effective for remediation monitoring. The strengths of oxygen and carbon dioxide sensors are complimentary to each other. Strengths and limitations of different hydrocarbon sensors were also noted. Balancing cost and performance of sensors is crucial for environmental remediation application.

  6. Geophysical Monitoring of Two types of Subsurface Injection

    Science.gov (United States)

    Nano-scale particles of zero-valent iron (ZVI) were injected into the subsurface at the 100-D area of the DOE Hanford facility. The intent of this iron injection was to repair a gap in the existing in-situ redox manipulation barrier located at the site. A number of geophysical me...

  7. Wastewater treatment performances of horizontal and vertical subsurface flow constructed wetland systems in tropical climate

    Directory of Open Access Journals (Sweden)

    Suwasa Kantawanichkul

    2013-10-01

    Full Text Available The study was carried out in 4 concrete beds: two vertical subsurface flow beds (dimension of 1x1.4 x 0.6 m3 and twohorizontal subsurface flow beds (dimension of 0.6 x 2.3x 0.6 m3 planted with Cyperus alternifolius L. Under the averagewastewater temperature of 27°C, the hydraulic loading rates (HLR were varied from 5 to 20 cm/d in order to obtain theoptimum operating conditions and compare the removal efficiency. The wastewater was intermittently fed into the verticalsubsurface flow beds (5 minutes on and 55 minutes off, and continuously into the horizontal subsurface flow beds. Themaximum removal efficiencies were found at the lowest hydraulic loading rate for both systems. The horizontal subsurfaceflow system had a higher removal rate than the vertical subsurface flow system in terms of COD (the removal rates at 5-20cm/d were 9.6-33.9 g/m2.d. The vertical subsurface flow system showed higher removal efficiency for TKN and NH4+-N, inevery hydraulic loading rate and the removal rates for TKN and NH4+-N were 0.4-1.1 g/m2.d, respectively. Furthermore, it wasfound that the uptake of N by plants in the horizontal flow system was higher than in the vertical flow system for everyhydraulic loading rate (HLR but the loss of N via adsorption/denitrification was higher in the vertical flow system than inthe horizontal flow system, at 20 cm/d HLR. The removal rate constants in the horizontal subsurface flow system for COD andNH4+-N were 0.0166 and 0.0188 m/d and 0.0204 and 0.0287 m/d for the vertical subsurface flow system, respectively

  8. Ethernet Flow Monitoring with IPFIX

    NARCIS (Netherlands)

    Hofstede, R.J.; Drago, Idilio; Sperotto, Anna; Pras, Aiko

    The increasing amount of network traffic and the huge bandwidth needed to carry it requires managers to use scalable solutions to monitor their networks. Nowadays, flow-based techniques, such as Cisco’s NetFlow, provide aggregated network data and an overview of network activity at the IP layer.

  9. Ethernet Flow Monitoring with IPFIX

    NARCIS (Netherlands)

    Hofstede, Rick; Drago, Idilio; Sperotto, Anna; Pras, Aiko

    2011-01-01

    The increasing amount of network traffic and the huge bandwidth needed to carry it requires managers to use scalable solutions to monitor their networks. Nowadays, flow-based techniques, such as Cisco’s NetFlow, provide aggregated network data and an overview of network activity at the IP layer. How

  10. Three-Dimensional Subsurface Flow, Fate and Transport of Microbes and Chemicals (3DFATMIC) Model

    Science.gov (United States)

    This model simulates subsurface flow, fate and transport of contaminants that are undergoing chemical or biological transformations. The model is applicable to transient conditions in both saturated and unsaturated zones.

  11. Research on Nitrogen Removal and Microorganism in a Subsurface Flow Constructed Wetland System in Sihong County

    Institute of Scientific and Technical Information of China (English)

    XIA Ning; LIU Han-hu; GUO Ru-mei; ZHANG Hong-zhen; YANG Kun

    2006-01-01

    Experiments in monitoring the removal of organic material and nitrogen and determining the amounts of microorganism at different sites in the subsurface flow constructed wetland in Sihong county were performed. The results show that the removal of CODCr agrees with the kinetic equation of a first order reaction. The removal of pollutants varies with different seasons. The removal rates of CODCr, NH3-N, TN in the spring are 15%-23% higher than those in the autumn. The amount of ammonifier is larger than that of denitrifying bacteria and the amount of denitrifying bacteria is larger than that of nitrosomonas. The amount of bacteria around the plant roots is larger than that on the surface of the packing medium. No apparent change is observed for the amount of denitrifying bacteria and nitrosomonas between spring and autumn.

  12. Wastewater Treatment Using Horizontal Subsurface Flow Constructed Wetland

    Directory of Open Access Journals (Sweden)

    S. Sarafraz

    2009-01-01

    Full Text Available The last few decades witnessed sharp focus on environment pollution and its impact on life in nature. Wetlands can be used for biological treatment of wastewater. Problem statement: Scarcity of water is considered as a global problem and Iran is one the countries which is facing water shortage problem. Pollution of water bodies restrict the availability of water for various uses. Treatment of waste water before disposal contributes to water conservation efforts. Constructed wetlands are techniques aim to polish water quality and reduce the harmful effect of effluent. Approach: In this study, four horizontal subsurface flow wetlands (HSSF were constructed at the Research Station of Tehran University, located in Karaj, Iran. The study was carried out from April to September, 2007. Gravel and zeoilte were used in this study as substrate. Gravel-beds with and without plants (called GP and G and gravel-beds mixed with (10% zeolite, with and without plants (called ZP and Z were examined to investigate the feasibility of treating synthetic wastewater which was specifically produced and modified to imitate agricultural wastewater. Results: The results of this study indicated that the system had acceptable pollutant removal efficiency and that both plants were found to be tolerant under the tested conditions. The wetland system could achieve the NO3-N removal of (79% in ZP, (86% in Z, (82% in GP and finally (87.94% in G. As for the P removal, the efficiencies of 93, 89, 81 and 76% were respectively achieved for ZP, GP, Z and G. The outflow concentrations of Pb and Cd were found to be under the detection limit; however, as for Zn, the removal efficiencies of 99.9, 99.76, 99.71 and 99.52% were concluded for ZP, Z, GP and G respectively. Conclusions/Recommendations: It can be concluded that constructed wetlands are efficient in removing Zn, Pb and Cd from agricultural wastewater. Plants types such as Phragmites Australis and Juncus Inflexus can contribute

  13. 2015 Groundwater Monitoring Report Project Shoal Area: Subsurface Correction Unit 447

    Energy Technology Data Exchange (ETDEWEB)

    Findlay, Rick [Navarro Research and Engineering, Oak Ridge, TN (United States)

    2016-04-01

    The Project Shoal Area in Nevada was the site of a 12-kiloton-yield underground nuclear test in 1963. Although the surface of the site has been remediated, investigation of groundwater contamination resulting from the test is still in the corrective action process. Annual sampling and hydraulic head monitoring are conducted at the site as part of the subsurface corrective action strategy. The corrective action strategy is currently focused on revising the site conceptual model (SCM) and evaluating the adequacy of the monitoring well network. Some aspects of the SCM are known; however, two major concerns are the uncertainty in the groundwater flow direction and the cause of rising water levels in site wells west of the shear zone. Water levels have been rising in the site wells west of the shear zone since the first hydrologic characterization wells were installed in 1996. Although water levels in wells west of the shear zone continue to rise, the rate of increase is less than in previous years. The SCM will be revised, and an evaluation of the groundwater monitoring network will be conducted when water levels at the site have stabilized to the agreement of both the U.S. Department of Energy Office of Legacy Management and the Nevada Division of Environmental Protection.

  14. Geoelectrical monitoring of simulated subsurface leakage to support high-hazard nuclear decommissioning at the Sellafield Site, UK.

    Science.gov (United States)

    Kuras, Oliver; Wilkinson, Paul B; Meldrum, Philip I; Oxby, Lucy S; Uhlemann, Sebastian; Chambers, Jonathan E; Binley, Andrew; Graham, James; Smith, Nicholas T; Atherton, Nick

    2016-10-01

    A full-scale field experiment applying 4D (3D time-lapse) cross-borehole Electrical Resistivity Tomography (ERT) to the monitoring of simulated subsurface leakage was undertaken at a legacy nuclear waste silo at the Sellafield Site, UK. The experiment constituted the first application of geoelectrical monitoring in support of decommissioning work at a UK nuclear licensed site. Images of resistivity changes occurring since a baseline date prior to the simulated leaks revealed likely preferential pathways of silo liquor simulant flow in the vadose zone and upper groundwater system. Geophysical evidence was found to be compatible with historic contamination detected in permeable facies in sediment cores retrieved from the ERT boreholes. Results indicate that laterally discontinuous till units forming localized hydraulic barriers substantially affect flow patterns and contaminant transport in the shallow subsurface at Sellafield. We conclude that only geophysical imaging of the kind presented here has the potential to provide the detailed spatial and temporal information at the (sub-)meter scale needed to reduce the uncertainty in models of subsurface processes at nuclear sites.

  15. Modelling rapid subsurface flow at the hillslope scale with explicit representation of preferential flow paths

    Science.gov (United States)

    Wienhöfer, J.; Zehe, E.

    2012-04-01

    Rapid lateral flow processes via preferential flow paths are widely accepted to play a key role for rainfall-runoff response in temperate humid headwater catchments. A quantitative description of these processes, however, is still a major challenge in hydrological research, not least because detailed information about the architecture of subsurface flow paths are often impossible to obtain at a natural site without disturbing the system. Our study combines physically based modelling and field observations with the objective to better understand how flow network configurations influence the hydrological response of hillslopes. The system under investigation is a forested hillslope with a small perennial spring at the study area Heumöser, a headwater catchment of the Dornbirnerach in Vorarlberg, Austria. In-situ points measurements of field-saturated hydraulic conductivity and dye staining experiments at the plot scale revealed that shrinkage cracks and biogenic macropores function as preferential flow paths in the fine-textured soils of the study area, and these preferential flow structures were active in fast subsurface transport of artificial tracers at the hillslope scale. For modelling of water and solute transport, we followed the approach of implementing preferential flow paths as spatially explicit structures of high hydraulic conductivity and low retention within the 2D process-based model CATFLOW. Many potential configurations of the flow path network were generated as realisations of a stochastic process informed by macropore characteristics derived from the plot scale observations. Together with different realisations of soil hydraulic parameters, this approach results in a Monte Carlo study. The model setups were used for short-term simulation of a sprinkling and tracer experiment, and the results were evaluated against measured discharges and tracer breakthrough curves. Although both criteria were taken for model evaluation, still several model setups

  16. CO2 exsolution - challenges and opportunities in subsurface flow management

    Science.gov (United States)

    Zuo, Lin; Benson, Sally

    2014-05-01

    for storage security. Falta et al. [2013] show that if carbonated brine migrates upwards and exsolution occurs, brine migration would be greatly reduced and limited by the presence of exsolved CO2 and the consequent low relatively permeability to brine. Similarly, if an exsolved CO2 phase were to evolve in seals, for example, after CO2 injection stops, the effect would be to reduce the permeability to brine and the CO2 would have very low mobility. This flow blocking effect is also studied with water/oil/CO2 [Zuo et al., 2013]. Experiments show that exsolved CO2 performs as a secondary residual phase in porous media that effectively blocks established water flow paths and deviates water to residual oil zones, thereby increasing recovery. Overall, our studies suggest that CO2 exsolution provides an opportunity for mobility control in subsurface processes. However, the lack of simulation capability that accounts for differences between gas injection and gas exsolution creates challenges for modeling and hence, designing studies to exploit the mobility reduction capabilities of CO2 exsolution. Using traditional drainage multiphase flow parameterization in simulations involving exsolution will lead to large errors in transport rates. Development of process dependent parameterizations of multiphase flow properties will be a key next step and will help to unlock the benefits from gas exsolution. ACKNOWLEDGEMENT This work is funded by the Global Climate and Energy Project (GCEP) at Stanford University. This work was also supported by U.S. EPA, Science To Achieve Results (STAR) Program, Grant #: 834383, 2010-2012. REFERENCES Falta, R., L. Zuo and S.M. Benson (2013). Migration of exsolved CO2 following depressurization of saturated brines. Journal of Greenhouse Gas Science and Technology, 3(6), 503-515. Zuo, L., S.C.M. Krevor, R.W. Falta, and S.M. Benson (2012). An experimental study of CO2 exsolution and relative permeability measurements during CO2 saturated water

  17. Subsurface flow in a soil-mantled subtropical dolomite karst slope: A field rainfall simulation study

    Science.gov (United States)

    Fu, Z. Y.; Chen, H. S.; Zhang, W.; Xu, Q. X.; Wang, S.; Wang, K. L.

    2015-12-01

    Soil and epikarst co-evolve resulting in complex structures, but their coupled structural effects on hydrological processes are poorly understood in karst regions. This study examined the plot-scale subsurface flow characteristics from an integrated soil-epikarst system perspective in a humid subtropical cockpit karst region of Southwest China. A trench was excavated to the epikarst lower boundary for collecting individual subsurface flows in five sections with different soil thicknesses. Four field rainfall simulation experiments were carried out under different initial moisture conditions (dry and wet) and rainfall intensities (114 mm h- 1 (high) and 46 mm h- 1 (low) on average). The soil-epikarst system was characterized by shallow soil overlaying a highly irregular epikarst surface with a near-steady infiltration rate of about 35 mm h- 1. The subsurface flows occurred mainly along the soil-epikarst interface and were dominated by preferential flow. The subsurface flow hydrographs showed strong spatial variability and had high steady-state coefficients (0.52 and 0.36 for high and low rainfall intensity events). Irregular epikarst surface combining with high vertical drainage capacity resulted in high threshold rainfall depths for subsurface flows: 67 mm and 263 mm for initial wet and dry conditions, respectively. The above results evidenced that the irregular and permeable soil-epikarst interface was a crucial component of soil-epikarst architecture and consequently should be taken into account in the hydrological modeling for karst regions.

  18. Joint geophysical and flow inversion to characterize fracture networks in subsurface systems

    CERN Document Server

    Mudunuru, M K; Makedonska, N; Chen, T

    2016-01-01

    Subsurface applications including geothermal, geological carbon sequestration, oil and gas, etc., typically involve maximizing either the extraction of energy or the storage of fluids. Characterizing the subsurface is extremely complex due to heterogeneity and anisotropy. Due to this complexity, there are uncertainties in the subsurface parameters, which need to be estimated from multiple diverse as well as fragmented data streams. In this paper, we present a non-intrusive joint inversion framework, for integrating data from geophysical and flow sources to constraint subsurface Discrete Fracture Networks (DFN). In this approach, we first estimate bounds on the statistics for the DFN fracture orientations using microseismic data. These bounds are estimated through a combination of a focal mechanism (physics-based approach) and clustering analysis (statistical approach) of seismic data. Then, the fracture lengths are constrained based on the flow data. The efficacy of this multi-physics based joint inversion is...

  19. Effects of rainfall patterns and land cover on the subsurface flow generation of sloping Ferralsols in southern China.

    Science.gov (United States)

    Duan, Jian; Yang, Jie; Tang, Chongjun; Chen, Lihua; Liu, Yaojun; Wang, Lingyun

    2017-01-01

    Rainfall patterns and land cover are two important factors that affect the runoff generation process. To determine the surface and subsurface flows associated with different rainfall patterns on sloping Ferralsols under different land cover types, observational data related to surface and subsurface flows from 5 m × 15 m plots were collected from 2010 to 2012. The experiment was conducted to assess three land cover types (grass, litter cover and bare land) in the Jiangxi Provincial Soil and Water Conservation Ecological Park. During the study period, 114 natural rainfall events produced subsurface flow and were divided into four groups using k-means clustering according to rainfall duration, rainfall depth and maximum 30-min rainfall intensity. The results showed that the total runoff and surface flow values were highest for bare land under all four rainfall patterns and lowest for the covered plots. However, covered plots generated higher subsurface flow values than bare land. Moreover, the surface and subsurface flows associated with the three land cover types differed significantly under different rainfall patterns. Rainfall patterns with low intensities and long durations created more subsurface flow in the grass and litter cover types, whereas rainfall patterns with high intensities and short durations resulted in greater surface flow over bare land. Rainfall pattern I had the highest surface and subsurface flow values for the grass cover and litter cover types. The highest surface flow value and lowest subsurface flow value for bare land occurred under rainfall pattern IV. Rainfall pattern II generated the highest subsurface flow value for bare land. Therefore, grass or litter cover are able to convert more surface flow into subsurface flow under different rainfall patterns. The rainfall patterns studied had greater effects on subsurface flow than on total runoff and surface flow for covered surfaces, as well as a greater effect on surface flows associated

  20. The Influence of Plant Root Systems on Subsurface Flow: Implications for Slope Stability

    Science.gov (United States)

    Although research has explained how plant roots mechanically stabilize soils, in this article we explore how root systems create networks of preferential flow and thus influence water pressures in soils to trigger landslides. Root systems may alter subsurface flow: Hydrological m...

  1. Investigations of subsurface flow constructed wetlands and associated geomaterial resources in the Akumal and Reforma regions, Quintana Roo, Mexico

    Science.gov (United States)

    Krekeler, Mark P. S.; Probst, Pete; Samsonov, Misha; Tselepis, Cynthia M.; Bates, William; Kearns, Lance E.; Maynard, J. Barry

    2007-12-01

    Subsurface flow constructed wetlands in the village of Akumal, Quintana Roo, Mexico were surveyed to determine the general status of the wetland systems and provide baseline information for long term monitoring and further study. Twenty subsurface flow wetlands were surveyed and common problems observed in the systems were overloading, poor plant cover, odor, and no secondary containment. Bulk mineral composition of aggregate from two subsurface flow constructed wetlands was determined to consist solely of calcite using bulk powder X-ray diffraction. Some soil structure is developed in the aggregate and aggregate levels in wetlands drop at an estimated rate between 3 and 10 cm/year for overloaded wetlands owing to dissolution. Mineral composition from fresh aggregate samples commonly is a mixture of calcite and aragonite. Trace amounts of Pb, Zn, Co, and Cr were observed in fresh aggregate. Coefficients of permeability ( k) varied from 0.006 to 0.027 cm/s with an average values being 0.016 cm/s. Grain size analysis of fresh aggregate samples indicates there are unimodal and multimodal size distributions in the samples with modes in the coarse and fine sand being common. Investigations of other geologic media from the Reforma region indicate that a dolomite with minor amounts of Fe-oxide and palygorskite is abundant and may be a better aggregate source that the current materials used. A Ca-montmorillonite bed was identified in the Reforma region as well and this unit is suitable to serve as a clay liner to prevent leaks for new and existing wetland systems. These newly discovered geologic resources should aid in the improvement of subsurface flow constructed wetlands in the region. Although problems do exist in these wetlands with respect to design, these systems represent a successful implementation of constructed wetlands at a community level in developing regions.

  2. Form and function in hillslope hydrology: characterization of subsurface flow based on response observations

    Science.gov (United States)

    Angermann, Lisa; Jackisch, Conrad; Allroggen, Niklas; Sprenger, Matthias; Zehe, Erwin; Tronicke, Jens; Weiler, Markus; Blume, Theresa

    2017-07-01

    The phrase form and function was established in architecture and biology and refers to the idea that form and functionality are closely correlated, influence each other, and co-evolve. We suggest transferring this idea to hydrological systems to separate and analyze their two main characteristics: their form, which is equivalent to the spatial structure and static properties, and their function, equivalent to internal responses and hydrological behavior. While this approach is not particularly new to hydrological field research, we want to employ this concept to explicitly pursue the question of what information is most advantageous to understand a hydrological system. We applied this concept to subsurface flow within a hillslope, with a methodological focus on function: we conducted observations during a natural storm event and followed this with a hillslope-scale irrigation experiment. The results are used to infer hydrological processes of the monitored system. Based on these findings, the explanatory power and conclusiveness of the data are discussed. The measurements included basic hydrological monitoring methods, like piezometers, soil moisture, and discharge measurements. These were accompanied by isotope sampling and a novel application of 2-D time-lapse GPR (ground-penetrating radar). The main finding regarding the processes in the hillslope was that preferential flow paths were established quickly, despite unsaturated conditions. These flow paths also caused a detectable signal in the catchment response following a natural rainfall event, showing that these processes are relevant also at the catchment scale. Thus, we conclude that response observations (dynamics and patterns, i.e., indicators of function) were well suited to describing processes at the observational scale. Especially the use of 2-D time-lapse GPR measurements, providing detailed subsurface response patterns, as well as the combination of stream-centered and hillslope-centered approaches

  3. Fractal topography and subsurface water flows from fluvial bedforms to the continental shield

    Science.gov (United States)

    Worman, A.; Packman, A.I.; Marklund, L.; Harvey, J.W.; Stone, S.H.

    2007-01-01

    Surface-subsurface flow interactions are critical to a wide range of geochemical and ecological processes and to the fate of contaminants in freshwater environments. Fractal scaling relationships have been found in distributions of both land surface topography and solute efflux from watersheds, but the linkage between those observations has not been realized. We show that the fractal nature of the land surface in fluvial and glacial systems produces fractal distributions of recharge, discharge, and associated subsurface flow patterns. Interfacial flux tends to be dominated by small-scale features while the flux through deeper subsurface flow paths tends to be controlled by larger-scale features. This scaling behavior holds at all scales, from small fluvial bedforms (tens of centimeters) to the continental landscape (hundreds of kilometers). The fractal nature of surface-subsurface water fluxes yields a single scale-independent distribution of subsurface water residence times for both near-surface fluvial systems and deeper hydrogeological flows. Copyright 2007 by the American Geophysical Union.

  4. 2012 Groundwater Monitoring Report Project Shoal Area Subsurface Corrective Action Unit 447

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-03-01

    The Project Shoal Area (PSA) in Nevada was the site of a 12-kiloton underground nuclear test in 1963. Although the surface of the site has been remediated, investigation of groundwater contamination resulting from the test is still in the corrective action process. Annual sampling and hydraulic head monitoring are conducted at the site as part of the subsurface corrective action strategy. Analytical results from the 2012 monitoring are consistent with those of the previous years, with tritium detected only in well HC-4. The tritium concentration in groundwater from well HC-4 remains far below the U.S. Environmental Protection Agency-established maximum contaminant level of 20,000 picocuries per liter. Concentrations of total uranium and gross alpha were also detected during this monitoring period, with uranium accounting for nearly all the gross alpha activity. The total uranium concentrations obtained from this monitoring period were consistent with previous results and reflect a slightly elevated natural uranium concentration, consistent with the mineralized geologic terrain. Isotopic ratios of uranium also indicate a natural source of uranium in groundwater, as opposed to a nuclear-test-related source. Water level trends obtained from the 2012 water level data were consistent with those of previous years. The corrective action strategy for the PSA is currently focused on revising the site conceptual model (SCM) and evaluating the adequacy of the current monitoring well network. Some aspects of the SCM are known; however, two major concerns are the uncertainty in the groundwater flow direction and the cause of rising water levels in site wells west of the shear zone. Water levels have been rising in the site wells west of the shear zone since the first hydrologic characterization wells were installed in 1996. While water levels in wells west of the shear zone continue to rise, the rate of increase is less than in previous years. The SCM will be revised, and an

  5. Evaluation of Deep Subsurface Resistivity Imaging for Hydrofracture Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Andrew [GroundMetrics, Inc., San Diego, CA (United States); Wilt, Michael [GroundMetrics, Inc., San Diego, CA (United States)

    2016-09-28

    This report describes the results of the first of its kind monitoring of a hydrofracture operation with electromagnetic measurements. The researchers teamed with oil and gas producer Encana Corporation to design and execute a borehole to surface monitoring of three fracture stages at a well pad in central Colorado. The field project consisted of an equipment upgrade, a survey design and modeling phase, several weeks of data collection, and data processing and interpretation. Existing Depth to Surface Resistivity (DSR) instrumentation was upgraded to allow for continuous high precision recording from downhole sources. The full system can now collect data continuously for up to 72 hours, which is sufficient to measure data for 10 frac stages. Next we used numerical modeling and frac treatment data supplied by Encana to design a field survey to detect EM signal from induced fractures. Prior to modeling we developed a novel technique for using well casing as an antenna for a downhole source. Modeling shows that 1) a measurable response for an induced fracture could be achieved if the facture fluid was of high salinity 2) an optimum fracture response is created when the primary source field is parallel to the well casing but perpendicular to the fracture direction. In mid-July, 2014 we installed an array of more than 100 surface sensors, distributed above the treatment wells and extending for approximately 1 km north and 750 m eastward. We applied a 0.6 Hz square wave signal to a downhole current electrode located in a horizontal well 200 m offset from the treatment well with a return electrode on the surface. The data were transmitted to a recording trailer via Wi-Fi where we monitored receiver and transmitter channels continuously in a 72-hour period which covered 7 frac stages, three of which were high salinity. Although the background conditions were very noisy we were able to extract a clear signal from the high salinity stages. Initial data interpretation attempts

  6. Analytical solutions to a hillslope-storage kinematic wave equation for subsurface flow

    NARCIS (Netherlands)

    Troch, P.A.; Loon, van E.; Hilberts, A.

    2002-01-01

    Hillslope response has traditionally been studied by means of the hydraulic groundwater theory. Subsurface flow from a one-dimensional hillslope with a sloping aquifer can be described by the Boussinesq equation [Mem. Acad. Sci. Inst. Fr. 23 (1) (1877) 252–260]. Analytical solutions to Boussinesq's

  7. A coupled surface/subsurface flow model accounting for air entrapment and air pressure counterflow

    DEFF Research Database (Denmark)

    Delfs, Jens Olaf; Wang, Wenqing; Kalbacher, Thomas

    2013-01-01

    This work introduces the soil air system into integrated hydrology by simulating the flow processes and interactions of surface runoff, soil moisture and air in the shallow subsurface. The numerical model is formulated as a coupled system of partial differential equations for hydrostatic (diffusive...

  8. FACT (Version 2.0) - Subsurface Flow and Contaminant Transport Documentation and User's Guide

    Energy Technology Data Exchange (ETDEWEB)

    Aleman, S.E.

    2000-05-05

    This report documents a finite element code designed to model subsurface flow and contaminant transport, named FACT. FACT is a transient three-dimensional, finite element code designed to simulate isothermal groundwater flow, moisture movement, and solute transport in variably saturated and fully saturated subsurface porous media.

  9. Warm season performance of horizontal subsurface flow constructed ...

    African Journals Online (AJOL)

    user

    2013-06-14

    Jun 14, 2013 ... 54 cm height) batch fed daily with water from a nearby urban stream ... of water quality of urban and peri-urban water resources. .... nearby monitored by The National Center of Cotton Research ... Respectively, in the first and second cultivation ... reflecting both respiration and organic matter degradation.

  10. Multi-Physics Markov Chain Monte Carlo Methods for Subsurface Flows

    Science.gov (United States)

    Rigelo, J.; Ginting, V.; Rahunanthan, A.; Pereira, F.

    2014-12-01

    For CO2 sequestration in deep saline aquifers, contaminant transport in subsurface, and oil or gas recovery, we often need to forecast flow patterns. Subsurface characterization is a critical and challenging step in flow forecasting. To characterize subsurface properties we establish a statistical description of the subsurface properties that are conditioned to existing dynamic and static data. A Markov Chain Monte Carlo (MCMC) algorithm is used in a Bayesian statistical description to reconstruct the spatial distribution of rock permeability and porosity. The MCMC algorithm requires repeatedly solving a set of nonlinear partial differential equations describing displacement of fluids in porous media for different values of permeability and porosity. The time needed for the generation of a reliable MCMC chain using the algorithm can be too long to be practical for flow forecasting. In this work we develop fast and effective computational methods for generating MCMC chains in the Bayesian framework for the subsurface characterization. Our strategy consists of constructing a family of computationally inexpensive preconditioners based on simpler physics as well as on surrogate models such that the number of fine-grid simulations is drastically reduced in the generated MCMC chains. In particular, we introduce a huff-puff technique as screening step in a three-stage multi-physics MCMC algorithm to reduce the number of expensive final stage simulations. The huff-puff technique in the algorithm enables a better characterization of subsurface near wells. We assess the quality of the proposed multi-physics MCMC methods by considering Monte Carlo simulations for forecasting oil production in an oil reservoir.

  11. Use of shredded tires as support medium for subsurface flow constructed wetland

    Directory of Open Access Journals (Sweden)

    Denis Miguel Roston

    2006-08-01

    Full Text Available This work evaluated shredded tires as a medium for constructed wetlands, treating domestic wastewater. The experiment was conducted utilizing effluent of a small Sewage Treatment Plant. Two tanks with 10 m2 each, with dimensions of 2 m wide, 5 m long and 1 m height were built above soil level using cement bricks. One of the tanks was filled out entirely with crushed stone (diameter 55 to 90 mm, while in the other tank the medium was shredded tires reaching the height of 0.80 m. Above the tires, a 0.10 m gravel layer to complete the total height (1 m and avoid floating. The aquatic macrophytes utilized were from Typha species distributed uniformly over the beds. The following parameters were monitored: suspended solids, pH, chemical oxygen demand, and ammonia nitrogen. The results were submitted to a statistical analysis in order to verify if significant difference existed (to 1 % and 5% of significance between the two treatments. The results demonstrate no significant difference for the parameter NH3-N, while for suspended solids and pH, were found significant differences to 1% and 5% of significance. For COD was found significant difference to 5% of significance. The results indicated a potential use of shredded tires to substitute the conventional media utilized for subsurface flow constructed wetlands.

  12. Phosphorus retention capacity of iron-ore and blast furnace slag in subsurface flow constructed wetlands.

    Science.gov (United States)

    Grüneberg, B; Kern, J

    2001-01-01

    The suitability of iron-ore and blast furnace slag for subsurface flow (SSF) constructed wetlands was studied over a period of four months. Dairy farm wastewater (TP 45 mg l(-1)) was percolated through buckets planted with reed (volume 9.1 l; hydraulic load 151 m(-2) d(-1)). One group of buckets was kept under aerobic conditions and the other group under anaerobic conditions, monitored by continuous redox potential measurements. Even at high mass loading rates of 0.65 g P m(-1) d(-1) the slag provided 98% removal efficiency and showed no decrease in performance with time. However, phosphorus fractionation data indicate that the high phosphorus retention capacity under aerobic conditions is to a great extent attributable to unstable sorption onto calcium compounds (NH4Cl-P). Phosphorus sorption of both the slag (200 microg P g(-1)) and the iron-ore (140 microg P g(-1)) was promoted by predominantly anaerobic conditions due to continuous formation of amorphous ferrous hydroxides. None of the substrates had adverse affects on reed growth.

  13. Coupled surface and subsurface flow modeling of natural hillslopes in the Aburrá Valley (Medellín, Colombia)

    Science.gov (United States)

    Blessent, Daniela; Barco, Janet; Temgoua, André Guy Tranquille; Echeverrri-Ramirez, Oscar

    2017-03-01

    Numerical results are presented of surface-subsurface water modeling of a natural hillslope located in the Aburrá Valley, in the city of Medellín (Antioquia, Colombia). The integrated finite-element hydrogeological simulator HydroGeoSphere is used to conduct transient variably saturated simulations. The objective is to analyze pore-water pressure and saturation variation at shallow depths, as well as volumes of water infiltrated in the porous medium. These aspects are important in the region of study, which is highly affected by soil movements, especially during the high-rain seasons that occur twice a year. The modeling exercise considers rainfall events that occurred between October and December 2014 and a hillslope that is currently monitored because of soil instability problems. Simulation results show that rainfall temporal variability, mesh resolution, coupling length, and the conceptual model chosen to represent the heterogeneous soil, have a noticeable influence on results, particularly for high rainfall intensities. Results also indicate that surface-subsurface coupled modeling is required to avoid unrealistic increase in hydraulic heads when high rainfall intensities cause top-down saturation of soil. This work is a first effort towards fostering hydrogeological modeling expertise that may support the development of monitoring systems and early landslide warning in a country where the rainy season is often the cause of hydrogeological tragedies associated with landslides, mud flow or debris flow.

  14. Coupled surface and subsurface flow modeling of natural hillslopes in the Aburrá Valley (Medellín, Colombia)

    Science.gov (United States)

    Blessent, Daniela; Barco, Janet; Temgoua, André Guy Tranquille; Echeverrri-Ramirez, Oscar

    2016-10-01

    Numerical results are presented of surface-subsurface water modeling of a natural hillslope located in the Aburrá Valley, in the city of Medellín (Antioquia, Colombia). The integrated finite-element hydrogeological simulator HydroGeoSphere is used to conduct transient variably saturated simulations. The objective is to analyze pore-water pressure and saturation variation at shallow depths, as well as volumes of water infiltrated in the porous medium. These aspects are important in the region of study, which is highly affected by soil movements, especially during the high-rain seasons that occur twice a year. The modeling exercise considers rainfall events that occurred between October and December 2014 and a hillslope that is currently monitored because of soil instability problems. Simulation results show that rainfall temporal variability, mesh resolution, coupling length, and the conceptual model chosen to represent the heterogeneous soil, have a noticeable influence on results, particularly for high rainfall intensities. Results also indicate that surface-subsurface coupled modeling is required to avoid unrealistic increase in hydraulic heads when high rainfall intensities cause top-down saturation of soil. This work is a first effort towards fostering hydrogeological modeling expertise that may support the development of monitoring systems and early landslide warning in a country where the rainy season is often the cause of hydrogeological tragedies associated with landslides, mud flow or debris flow.

  15. Development, testing and application of DrainFlow: A fully distributed integrated surface-subsurface flow model for drainage study

    Science.gov (United States)

    Shokri, Ali; Bardsley, William Earl

    2016-06-01

    Hydrological and hydrogeological investigation of drained land is a complex and integrated procedure. The scale of drainage studies may vary from a high-resolution small scale project through to comprehensive catchment or regional scale investigations. This wide range of scales and integrated system behaviour poses a significant challenge for the development of suitable drainage models. Toward meeting these requirements, a fully distributed coupled surface-subsurface flow model titled DrainFlow has been developed and is described. DrainFlow includes both the diffusive wave equation for surface flow components (overland flow, open drain, tile drain) and Richard's equation for saturated/unsaturated zones. To overcome the non-linearity problem created from switching between wet and dry boundaries, a smooth transitioning technique is introduced to buffer the model at tile drains and at interfaces between surface and subsurface flow boundaries. This gives a continuous transition between Dirichlet and Neumann boundary conditions. DrainFlow is tested against five well-known integrated surface-subsurface flow benchmarks. DrainFlow as applied to some synthetic drainage study examples is quite flexible for changing all or part of the model dimensions as required by problem complexity, problem scale, and data availability. This flexibility enables DrainFlow to be modified to allow for changes in both scale and boundary conditions, as often encountered in real-world drainage studies. Compared to existing drainage models, DrainFlow has the advantage of estimating actual infiltration directly from the partial differential form of Richard's equation rather than through analytical or empirical infiltration approaches like the Green and Ampt equation.

  16. Dissecting the variable source area concept - Subsurface flow pathways and water mixing processes in a hillslope

    Science.gov (United States)

    Dahlke, Helen E.; Easton, Zachary M.; Lyon, Steve W.; Todd Walter, M.; Destouni, Georgia; Steenhuis, Tammo S.

    2012-02-01

    SummaryThis study uses an instrumented (trenched) 0.5 ha hillslope in the southern tier of New York State, USA, to provide new data and insights on how variable source areas and associated flow pathways form and combine to connect rainfall with downstream water flows across a hillslope. Measurements of water fluxes in the trench, upslope water table dynamics, surface and bedrock topography, and isotopic and geochemical tracers have been combined for a four-dimensional (space-time) characterization of subsurface storm flow responses. During events with dry antecedent conditions infiltrating rainwater was found to percolate through a prevailing fragipan layer to deeper soil layers, with much (33-71%) of the total discharge of the hillslope originating from deeper water flow below the fragipan. During storm events with wet antecedent conditions and large rainfall amounts, shallow lateral flow of event and pre-event water above the fragipan occurred and was one magnitude greater than the deeper water flow contribution. Spatial surface and subsurface water quality observations indicate that water from a distance of up to 56 m contributed runoff from the hillslope during storm events. In addition, mobilization of total dissolved phosphorus (TDP) with subsurface flow played a greater role than with overland or near-surface flow. During all events TDP loads were highest in the total discharge during peak flows (8-11.5 kg ha -1 d -1), except during the largest storm event, when TDP concentrations were highly diluted. These results have implications for strategies to protect streams and other downstream water recipients from waterborne nutrient and pollutant loading.

  17. Integrated Coupling of Surface and Subsurface Flow with HYDRUS-2D

    Science.gov (United States)

    Hartmann, Anne; Šimůnek, Jirka; Wöhling, Thomas; Schütze, Niels

    2016-04-01

    Describing interactions between surface and subsurface flow processes is important to adequately define water flow in natural systems. Since overland flow generation is highly influenced by rainfall and infiltration, both highly spatially heterogeneous processes, overland flow is unsteady and varies spatially. The prediction of overland flow needs to include an appropriate description of the interactions between the surface and subsurface flow. Coupling surface and subsurface water flow is a challenging task. Different approaches have been developed during the last few years, each having its own advantages and disadvantages. A new approach by Weill et al. (2009) to couple overland flow and subsurface flow based on a generalized Richards equation was implemented into the well-known subsurface flow model HYDRUS-2D (Šimůnek et al., 2011). This approach utilizes the one-dimensional diffusion wave equation to model overland flow. The diffusion wave model is integrated in HYDRUS-2D by replacing the terms of the Richards equation in a pre-defined runoff layer by terms defining the diffusion wave equation. Using this approach, pressure and flux continuity along the interface between both flow domains is provided. This direct coupling approach provides a strong coupling of both systems based on the definition of a single global system matrix to numerically solve the coupled flow problem. The advantage of the direct coupling approach, compared to the loosely coupled approach, is supposed to be a higher robustness, when many convergence problems can be avoided (Takizawa et al., 2014). The HYDRUS-2D implementation was verified using a) different test cases, including a direct comparison with the results of Weill et al. (2009), b) an analytical solution of the kinematic wave equation, and c) the results of a benchmark test of Maxwell et al. (2014), that included several known coupled surface subsurface flow models. Additionally, a sensitivity analysis evaluating the effects

  18. Treatment of laboratory wastewater in a tropical constructed wetland comparing surface and subsurface flow.

    Science.gov (United States)

    Meutia, A A

    2001-01-01

    Wastewater treatment by constructed wetland is an appropriate technology for tropical developing countries like Indonesia because it is inexpensive, easily maintained, and has environmentally friendly and sustainable characteristics. The aim of the research is to examine the capability of constructed wetlands for treating laboratory wastewater at our Center, to investigate the suitable flow for treatment, namely vertical subsurface or horizontal surface flow, and to study the effect of the seasons. The constructed wetland is composed of three chambered unplanted sedimentation tanks followed by the first and second beds, containing gravel and sand, planted with Typha sp.; the third bed planted with floating plant Lemna sp.; and a clarifier with two chambers. The results showed that the subsurface flow in the dry season removed 95% organic carbon (COD) and total phosphorus (T-P) respectively, and 82% total nitrogen (T-N). In the transition period from the dry season to the rainy season, COD removal efficiency decreased to 73%, T-N increased to 89%, and T-P was almost the same as that in the dry season. In the rainy season COD and T-N removal efficiencies increased again to 95% respectively, while T-P remained unchanged. In the dry season, COD and T-P concentrations in the surface flow showed that the removal efficiencies were a bit lower than those in the subsurface flow. Moreover, T-N removal efficiency was only half as much as that in the subsurface flow. However, in the transition period, COD removal efficiency decreased to 29%, while T-N increased to 74% and T-P was still constant, around 93%. In the rainy season, COD and T-N removal efficiencies increased again to almost 95%. On the other hand, T-P decreased to 76%. The results show that the constructed wetland is capable of treating the laboratory wastewater. The subsurface flow is more suitable for treatment than the surface flow, and the seasonal changes have effects on the removal efficiency.

  19. Tillage impact on herbicide loss by surface runoff and lateral subsurface flow.

    Science.gov (United States)

    Potter, Thomas L; Bosch, David D; Strickland, Timothy C

    2015-10-15

    There is worldwide interest in conservation tillage practices because they can reduce surface runoff, and agrichemical and sediment losses from farm fields. Since these practices typically increase infiltration, their use may increase subsurface transport of water-soluble contaminants. Thus, to assess long-term environmental benefits of conservation tillage data may be needed that quantify both surface and subsurface contaminant fluxes. This study focused on the herbicide fluometuron (N,N-dimethyl-N'-[3-(trifluoromethyl)phenyl]-urea) and its soil degradate DMF (N-methyl-N'-[3-(trifluoromethyl) phenyl]-urea). Both compounds are classed as "leachable". They were measured for 10 years in surface runoff and lateral subsurface flow from paired fields located on a hill slope in the Atlantic Coastal Plain region of the southeastern USA. One group of fields was conventionally tilled incorporating all crop residues into soil prior to planting. The second was strip tilled, a common conservation tillage practice. Seven fluometuron applications were made to cotton (Gossypium hirsutum) produced in rotation with peanut (Arachis hypogea). Combined fluometuron and DMF surface and subsurface losses from the conventionally tilled fields were equivalent to 1.2% and 0.13% of fluometuron applied and 0.31% and 0.32% from the strip tilled fields. Annual surface runoff losses were significantly greater from the conventionally tilled fields while the strip tilled fields had significantly greater annual subsurface losses. Results demonstrated that shifting from conventional to conservation tillage management of farm fields in this landscape will reduce surface runoff losses of herbicides like fluometuron but subsurface losses will likely increase. The same trends can be expected in landscapes with similar soil and hydrologic properties. This should be considered when planning implementation of programs that promote conservation tillage use.

  20. Subsurface Flow and Contaminant Transport Documentation and User's Guide

    Energy Technology Data Exchange (ETDEWEB)

    Aleman, S.E.

    1999-07-28

    This report documents a finite element code designed to model subsurface flow and contaminant transport, named FACT. FACT is a transient three-dimensional, finite element code designed to simulate isothermal groundwater flow, moisture movement, and solute transport in variably saturated and fully saturated subsurface porous media. The code is designed specifically to handle complex multi-layer and/or heterogeneous aquifer systems in an efficient manner and accommodates a wide range of boundary conditions. Additionally, 1-D and 2-D (in Cartesian coordinates) problems are handled in FACT by simply limiting the number of elements in a particular direction(s) to one. The governing equations in FACT are formulated only in Cartesian coordinates.

  1. A trench study to assess transfer of pesticides in subsurface lateral flow for a soil with contrasting texture on a sloping vineyard in Beaujolais.

    Science.gov (United States)

    Peyrard, X; Liger, L; Guillemain, C; Gouy, V

    2016-01-01

    Subsurface lateral flow in both texture-contrast soils and catchments with shallow bedrock is suspected to be a non-point source of contamination of watercourses by pesticides used in agriculture. As a case study, the north of the Beaujolais region (eastern France) provides a favorable environment for such contamination due to its agro-pedo-climatic conditions. Environments seen in the Beaujolais region include intense viticulture, permeable and shallow soils, steep hillslopes, and storms that occur during the periods of pesticide application. Watercourse contamination by pesticides has been widely observed in this region, and offsite pesticide transport by subsurface lateral flow is suspected to be involved in diffuse and chronic presence of pesticides in surface water. In order to confirm and quantify the potential role of such processes in pesticide transfer, an automated trench system has been designed. The trench was set up on a steep farmed hillslope in a texture-contrast soil. It was equipped with a tipping bucket flow meter and an automatic sampler to monitor pesticide concentrations in lateral flow at fine resolution, by means of a flow-dependent sampling strategy. Four pesticides currently used in vine growing were studied to provide a range of mobility properties: one insecticide (chlorpyrifos-methyl) and three fungicides (spiroxamine, tebuconazole, and dimethomorph). With this system, it was possible to study pesticide concentration dynamics in the subsurface lateral flow, generated by substantial rainfall events following pesticide applications. The experimental design ascertained to be a suitable method in which to monitor subsurface lateral flow and related transfer of pesticides.

  2. A Hardy Plant Facilitates Nitrogen Removal via Microbial Communities in Subsurface Flow Constructed Wetlands in Winter

    OpenAIRE

    Penghe Wang; Hui Zhang; Jie Zuo; Dehua Zhao; Xiangxu Zou; Zhengjie Zhu; Nasreen Jeelani; Xin Leng; Shuqing An

    2016-01-01

    The plants effect in subsurface flow constructed wetlands (SSF-CWs) is controversial, especially at low temperatures. Consequently, several SSF-CWs planted with Iris pseudacorus (CWI) or Typha orientalis Presl. (CWT) and several unplanted ones (CWC) were set up and fed with secondary effluent of sewage treatment plant during the winter in Eastern China. The 16S rDNA Illumina Miseq sequencing analysis indicated the positive effects of I. pseudacorus on the bacterial community richness and dive...

  3. Nested sampling algorithm for subsurface flow model selection, uncertainty quantification, and nonlinear calibration

    KAUST Repository

    Elsheikh, A. H.

    2013-12-01

    Calibration of subsurface flow models is an essential step for managing ground water aquifers, designing of contaminant remediation plans, and maximizing recovery from hydrocarbon reservoirs. We investigate an efficient sampling algorithm known as nested sampling (NS), which can simultaneously sample the posterior distribution for uncertainty quantification, and estimate the Bayesian evidence for model selection. Model selection statistics, such as the Bayesian evidence, are needed to choose or assign different weights to different models of different levels of complexities. In this work, we report the first successful application of nested sampling for calibration of several nonlinear subsurface flow problems. The estimated Bayesian evidence by the NS algorithm is used to weight different parameterizations of the subsurface flow models (prior model selection). The results of the numerical evaluation implicitly enforced Occam\\'s razor where simpler models with fewer number of parameters are favored over complex models. The proper level of model complexity was automatically determined based on the information content of the calibration data and the data mismatch of the calibrated model.

  4. On the role of high performance computing for simulating subsurface flow and chemical migration

    Energy Technology Data Exchange (ETDEWEB)

    Tompson, A.; Ashby, S.; Falgout, R.; Smith, S.

    1993-06-01

    The use of large-scale computing for simulating fluid flow and chemical migration in subsurface formations is reviewed. Increasingly, intensive, highly-resolved model calculations are being used experimentally to study the impacts of small-scale material heterogeneities on coupled flow and transport phenomena, and are becoming easier to carry out with advanced computing hardware. These issues are illustrated through an example problem focused on the calculation of steady fluid flow and chemical migration in a detailed, three-dimensional formation with synthetically-derived nonuniformities in material properties. Here the interest is in examining the coupled impacts on chemical mobility induced by nonuniform sorption reactions and heterogeneous flow fields. Ongoing activities are now emphasizing parallel computations for larger, dynamic, and nonlinear (two-phase) flow problems, improved interpretive methods for defining detailed material property distributions, as well as specific applications at real field sites.

  5. Solar-Cycle Variation of Subsurface-Flow Divergence: A Proxy of Magnetic Activity?

    Science.gov (United States)

    Komm, R.; Howe, R.; Hill, F.

    2017-09-01

    We study the solar-cycle variation of subsurface flows from the surface to a depth of 16 Mm. We have analyzed Global Oscillation Network Group (GONG) Dopplergrams with a ring-diagram analysis covering about 15 years and Helioseismic and Magnetic Imager (HMI) Dopplergrams covering more than 6 years. After subtracting the average rotation rate and meridional flow, we have calculated the divergence of the horizontal residual flows from the maximum of Solar Cycle 23 through the declining phase of Cycle 24. The subsurface flows are mainly divergent at quiet regions and convergent at locations of high magnetic activity. The relationship is essentially linear between divergence and magnetic activity at all activity levels at depths shallower than about 10 Mm. At greater depths, the relationship changes sign at locations of high activity; the flows are increasingly divergent at locations with a magnetic activity index (MAI) greater than about 24 G. The flows are more convergent by about a factor of two during the rising phase of Cycle 24 than during the declining phase of Cycle 23 at locations of medium and high activity (about 10 to 40 G MAI) from the surface to at least 10 Mm. The subsurface divergence pattern of Solar Cycle 24 first appears during the declining phase of Cycle 23 and is present during the extended minimum. It appears several years before the magnetic pattern of the new cycle is noticeable in synoptic maps. Using linear regression, we estimate the amount of magnetic activity that would be required to generate the precursor pattern and find that it should be almost twice the amount of activity that is observed.

  6. Rain and channel flow supplements to subsurface water beneath hyper-arid ephemeral stream channels

    Science.gov (United States)

    Kampf, Stephanie K.; Faulconer, Joshua; Shaw, Jeremy R.; Sutfin, Nicholas A.; Cooper, David J.

    2016-05-01

    In hyper-arid regions, ephemeral stream channels are important sources of subsurface recharge and water supply for riparian vegetation, but few studies have documented the subsurface water content dynamics of these systems. This study examines ephemeral channels in the hyper-arid western Sonoran Desert, USA to determine how frequently water recharges the alluvial fill and identify variables that affect the depth and persistence of recharge. Precipitation, stream stage, and subsurface water content measurements were collected over a three-year study at six channels with varying contributing areas and thicknesses of alluvial fill. All channels contain coarse alluvium composed primarily of sands and gravels, and some locations also have localized layers of fine sediment at 2-3 m depth. Rain alone contributed 300-400 mm of water input to these channels over three years, but water content responses were only detected for 36% of the rain events at 10 cm depth, indicating that much of the rain water was either quickly evaporated or taken up by plants. Pulses of water from rain events were detected only in the top meter of alluvium. The sites each experienced ⩽5 brief flow events, which caused transient saturation that usually lasted only a few hours longer than flow. These events were the only apparent source of water to depths >1 m, and water from flow events quickly percolated past the deepest measurement depths (0.5-3 m). Sustained saturation in the shallow subsurface only developed where there was a near-surface layer of finer consolidated sediments that impeded deep percolation.

  7. Statistical Analysis of Nitrogen in the Soil of Constructed Wetland with Horizontal Sub-Surface Flow

    Directory of Open Access Journals (Sweden)

    Jakubaszek Anita

    2014-06-01

    Full Text Available The removal of nitrogen compounds in constructed wetlands depends on various physical, chemical and biomechanical factors as well as on conditions of the environment. The paper presents the results of a statistical analysis of the depositing of nitrogen at HSSF (horizontal subsurface flow construcred wetland. The results of the substrate showed that the highest contents of nitrogen existed in the surface soil layer up to 20 cm of the depth. Nitrogen accumulation decreased in the deposit with depth, and in the direction of the wastewater flow.

  8. Subsurface Contaminant Focus Area: Monitored Natural Attenuation (MNA)--Programmatic, Technical, and Regulatory Issues

    Energy Technology Data Exchange (ETDEWEB)

    Krupka, Kenneth M.; Martin, Wayne J.

    2001-07-23

    Natural attenuation processes are commonly used for remediation of contaminated sites. A variety of natural processes occur without human intervention at all sites to varying rates and degrees of effectiveness to attenuate (decrease) the mass, toxicity, mobility, volume, or concentration of organic and inorganic contaminants in soil, groundwater, and surface water systems. The objective of this review is to identify potential technical investments to be incorporated in the Subsurface Contaminant Focus Area Strategic Plan for monitored natural attenuation. When implemented, the technical investments will help evaluate and implement monitored natural attenuation as a remediation option at DOE sites. The outcome of this review is a set of conclusions and general recommendations regarding research needs, programmatic guidance, and stakeholder issues pertaining to monitored natural attenuation for the DOE complex.

  9. Evidence for debris flow gully formation initiated by shallow subsurface water on Mars

    Science.gov (United States)

    Lanza, N.L.; Meyer, G.A.; Okubo, C.H.; Newsom, Horton E.; Wiens, R.C.

    2010-01-01

    The morphologies of some martian gullies appear similar to terrestrial features associated with debris flow initiation, erosion, and deposition. On Earth, debris flows are often triggered by shallow subsurface throughflow of liquid water in slope-mantling colluvium. This flow causes increased levels of pore pressure and thus decreased shear strength, which can lead to slide failure of slope materials and subsequent debris flow. The threshold for pore pressure-induced failure creates a distinct relationship between the contributing area supplying the subsurface flow and the slope gradient. To provide initial tests of a similar debris flow initiation hypothesis for martian gullies, measurements of the contributing areas and slope gradients were made at the channel heads of martian gullies seen in three HiRISE stereo pairs. These gullies exhibit morphologies suggestive of debris flows such as leveed channels and lobate debris fans, and have well-defined channel heads and limited evidence for multiple flows. Our results show an area-slope relationship for these martian gullies that is consistent with that observed for terrestrial gullies formed by debris flow, supporting the hypothesis that these gullies formed as the result of saturation of near-surface regolith by a liquid. This model favors a source of liquid that is broadly distributed within the source area and shallow; we suggest that such liquid could be generated by melting of broadly distributed icy materials such as snow or permafrost. This interpretation is strengthened by observations of polygonal and mantled terrain in the study areas, which are both suggestive of near-surface ice. ?? 2009 Elsevier Inc.

  10. Akuna - Integrated Toolsets Supporting Advanced Subsurface Flow and Transport Simulations for Environmental Management

    Energy Technology Data Exchange (ETDEWEB)

    Schuchardt, Karen L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Agarwal, Deborah A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Finsterle, Stefan A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gable, Carl W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gorton, Ian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gosink, Luke J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Keating, Elizabeth H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lansing, Carina S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Meyer, Joerg [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Moeglein, William A.M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pau, George S.H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Porter, Ellen A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Purohit, Sumit [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rockhold, Mark L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shoshani, Arie [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sivaramakrishnan, Chandrika [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2012-04-24

    A next generation open source subsurface simulator and user environment for environmental management is being developed through a collaborative effort across Department of Energy National Laboratories. The flow and transport simulator, Amanzi, will be capable of modeling complex subsurface environments and processes using both unstructured and adaptive meshes at very fine spatial resolutions that require supercomputing-scale resources. The user environment, Akuna, provides users with a range of tools to manage environmental and simulator data sets, create models, manage and share simulation data, and visualize results. Underlying the user interface are core toolsets that provide algorithms for sensitivity analysis, parameter estimation, and uncertainty quantification. Akuna is open-source, cross platform software that is initially being demonstrated on the Hanford BC Cribs remediation site. In this paper, we describe the emerging capabilities of Akuna and illustrate how these are being applied to the BC Cribs site.

  11. [Correlation of substrate structure and hydraulic characteristics in subsurface flow constructed wetlands].

    Science.gov (United States)

    Bai, Shao-Yuan; Song, Zhi-Xin; Ding, Yan-Li; You, Shao-Hong; He, Shan

    2014-02-01

    The correlation of substrate structure and hydraulic characteristics was studied by numerical simulation combined with experimental method. The numerical simulation results showed that the permeability coefficient of matrix had a great influence on hydraulic efficiency in subsurface flow constructed wetlands. The filler with a high permeability coefficient had a worse flow field distribution in the constructed wetland with single layer structure. The layered substrate structure with the filler permeability coefficient increased from surface to bottom could avoid the short-circuited flow and dead-zones, and thus, increased the hydraulic efficiency. Two parallel pilot-scale constructed wetlands were built according to the numerical simulation results, and tracer experiments were conducted to validate the simulation results. The tracer experiment result showed that hydraulic characteristics in the layered constructed wetland were obviously better than that in the single layer system, and the substrate effective utilization rates were 0.87 and 0.49, respectively. It was appeared that numerical simulation would be favorable for substrate structure optimization in subsurface flow constructed wetlands.

  12. Intermediate-Scale Laboratory Experiments of Subsurface Flow and Transport Resulting from Tank Leaks

    Energy Technology Data Exchange (ETDEWEB)

    Oostrom, Martinus; Wietsma, Thomas W.

    2014-09-30

    Washington River Protection Solutions contracted with Pacific Northwest National Laboratory to conduct laboratory experiments and supporting numerical simulations to improve the understanding of water flow and contaminant transport in the subsurface between waste tanks and ancillary facilities at Waste Management Area C. The work scope included two separate sets of experiments: •Small flow cell experiments to investigate the occurrence of potential unstable fingering resulting from leaks and the limitations of the STOMP (Subsurface Transport Over Multiple Phases) simulator to predict flow patterns and solute transport behavior under these conditions. Unstable infiltration may, under certain conditions, create vertically elongated fingers potentially transporting contaminants rapidly through the unsaturated zone to groundwater. The types of leak that may create deeply penetrating fingers include slow release, long duration leaks in relatively permeable porous media. Such leaks may have occurred below waste tanks at the Hanford Site. •Large flow experiments to investigate the behavior of two types of tank leaks in a simple layered system mimicking the Waste Management Area C. The investigated leaks include a relatively large leak with a short duration from a tank and a long duration leak with a relatively small leakage rate from a cascade line.

  13. 3-D numerical investigation of subsurface flow in anisotropic porous media using multipoint flux approximation method

    KAUST Repository

    Negara, Ardiansyah

    2013-01-01

    Anisotropy of hydraulic properties of subsurface geologic formations is an essential feature that has been established as a consequence of the different geologic processes that they undergo during the longer geologic time scale. With respect to petroleum reservoirs, in many cases, anisotropy plays significant role in dictating the direction of flow that becomes no longer dependent only on the pressure gradient direction but also on the principal directions of anisotropy. Furthermore, in complex systems involving the flow of multiphase fluids in which the gravity and the capillarity play an important role, anisotropy can also have important influences. Therefore, there has been great deal of motivation to consider anisotropy when solving the governing conservation laws numerically. Unfortunately, the two-point flux approximation of finite difference approach is not capable of handling full tensor permeability fields. Lately, however, it has been possible to adapt the multipoint flux approximation that can handle anisotropy to the framework of finite difference schemes. In multipoint flux approximation method, the stencil of approximation is more involved, i.e., it requires the involvement of 9-point stencil for the 2-D model and 27-point stencil for the 3-D model. This is apparently challenging and cumbersome when making the global system of equations. In this work, we apply the equation-type approach, which is the experimenting pressure field approach that enables the solution of the global problem breaks into the solution of multitude of local problems that significantly reduce the complexity without affecting the accuracy of numerical solution. This approach also leads in reducing the computational cost during the simulation. We have applied this technique to a variety of anisotropy scenarios of 3-D subsurface flow problems and the numerical results demonstrate that the experimenting pressure field technique fits very well with the multipoint flux approximation

  14. A physically-based integrated numerical model for flow, upland erosion, and contaminant transport in surface-subsurface systems

    Institute of Scientific and Technical Information of China (English)

    HE ZhiGuo; WU WeiMing

    2009-01-01

    This paper presents a physically-based integrated hydrologic model that can simulate the rain-fall-induced 2D surface water flow, 3D variably saturated subsurface flow, upland soil erosion and transport, and contaminant transport in the surface-subsurface system of a watershed.The model couples surface and subsurface flows based on the assumption of continuity conditions of pressure head and exchange flux at the ground, considering infiltration and evapotranspiration.The upland rill/interrill soil erosion and transport are simulated using a non-equilibrium transport model.Con-taminant transport in the integrated surface and subsurface domains is simulated using advec-tion-diffusion equations with mass changes due to sediment sorption and desorption and exchanges between two domains due to infiltration, diffusion, and bed change.The model requires no special treatments at the interface of upland areas and streams and is suitable for wetland areas and agricul-tural watersheds with shallow streams.

  15. The Development of a Sub-Surface Monitoring System for Organic Contamination in Soils and Groundwater

    Directory of Open Access Journals (Sweden)

    Sharon L. Huntley

    2002-01-01

    Full Text Available A major problem when dealing with environmental contamination is the early detection and subsequent surveillance of the contamination. This paper describes the potential of sub-surface sensor technology for the early detection of organic contaminants in contaminated soils, sediments, and landfill sites. Rugged, low-power hydrocarbon sensors have been developed, along with a data-logging system, for the early detection of phase hydrocarbons in soil. Through laboratory-based evaluation, the ability of this system to monitor organic contamination in water-based systems is being evaluated. When used in conjunction with specific immunoassays, this can provide a sensitive and low-cost solution for long-term monitoring and analysis, applicable to a wide range of field applications.

  16. Flow and transport processes in a macroporous subsurface-drained glacial till soil

    DEFF Research Database (Denmark)

    Villholth, Karen G.; Jensen, Karsten Høgh

    1998-01-01

    -scale concentration gradients, is questioned. Decreasing the domain exchange resulted in an improved model correspondence with the drainage chemograph. The drainage flow pattern was altered between drainage seasons owing to the changes in hydraulic efficiency of surface-vented macropores influenced by the physical......The experimental results from a field-scale tracer experiment in a subsurface-drained glacial till soil were analyzed by the application of a single/dual porosity model (MACRO), optionally accounting for concurrent and interacting flow and transport in the bulk soil porosity as well...... as in the macropores. The model analysis showed that macropore flow is essential in describing the observed transport phenomenon on a short as well as a longer time scale. The diffusive exchange of solute between the matrix and the macropores was very sensitive and critical for the model prediction of the drainage...

  17. Effect of spray aeration on organics and nitrogen removal in vertical subsurface flow constructed wetland.

    Science.gov (United States)

    Ding, Yi; Wang, Wei; Song, Xin-Shan; Wang, Gang; Wang, Yu-Hui

    2014-12-01

    The objective of present study was to assess the simultaneous removal of organics and nitrogen by four lab-scale vertical subsurface flow constructed wetlands (V-SFCWs). The emergent plants employed were Canna indica. Five-month experiments showed that the planted and aerated system largely reduced the COD by 95%, NH4 by 88% and total inorganic nitrogen (TIN) by 83%. It outperformed the unplanted or simple aerated system and was much better than non-aerated system. The study provided a strong evidence to support widespread research and application of spray aeration as a low-cost and energy-efficient aeration technology in V-SFCWs.

  18. Subsurface lateral flow from hillslope and its contribution to nitrate loading in streams through an agricultural catchment during subtropical rainstorm events

    Science.gov (United States)

    Zhang, B.; Tang, J. L.; Gao, Ch.; Zepp, H.

    2011-10-01

    Subsurface lateral flow from agricultural hillslopes is often overlooked compared with overland flow and tile drain flow, partly due to the difficulties in monitoring and quantifying. The objectives of this study were to examine how subsurface lateral flow generated through soil pedons from cropped hillslopes and to quantify its contribution to nitrate loading in the streams through an agricultural catchment in the subtropical region of China. Profiles of soil water potential along hillslopes and stream hydro-chemographs in a trenched stream below a cropped hillslope and at the catchment outlet were simultaneously recorded during two rainstorm events. The dynamics of soil water potential showed positive matrix soil water potential over impermeable soil layer at 0.6 to 1.50 m depths during and after the storms, indicating soil water saturation and drainage processes along the hillslopes irrespective of land uses. The hydro-chemographs in the streams, one trenched below a cropped hillslope and one at the catchment outlet, showed that the concentrations of particulate nitrogen and phosphorus corresponded well to stream flow during the storm, while the nitrate concentration increased on the recession limbs of the hydrographs after the end of the storm. All the synchronous data revealed that nitrate was delivered from the cropped hillslope through subsurface lateral flow to the streams during and after the end of the rainstorms. A chemical mixing model based on electricity conductivity (EC) and H+ concentration was successfully established, particularly for the trenched stream. The results showed that the subsurface lateral flow accounted for 29% to 45% of total stream flow in the trenched stream, responsible for 86% of total NO3--N loss (or 26% of total N loss), and for 5.7% to 7.3% of total stream flow at the catchment outlet, responsible for about 69% of total NO3--N loss (or 28% of total N loss). The results suggest that subsurface lateral flow through hydraulically

  19. Subsurface lateral flow from hillslope and its contribution to nitrate loading in streams through an agricultural catchment during subtropical rainstorm events

    Directory of Open Access Journals (Sweden)

    B. Zhang

    2011-10-01

    Full Text Available Subsurface lateral flow from agricultural hillslopes is often overlooked compared with overland flow and tile drain flow, partly due to the difficulties in monitoring and quantifying. The objectives of this study were to examine how subsurface lateral flow generated through soil pedons from cropped hillslopes and to quantify its contribution to nitrate loading in the streams through an agricultural catchment in the subtropical region of China. Profiles of soil water potential along hillslopes and stream hydro-chemographs in a trenched stream below a cropped hillslope and at the catchment outlet were simultaneously recorded during two rainstorm events. The dynamics of soil water potential showed positive matrix soil water potential over impermeable soil layer at 0.6 to 1.50 m depths during and after the storms, indicating soil water saturation and drainage processes along the hillslopes irrespective of land uses. The hydro-chemographs in the streams, one trenched below a cropped hillslope and one at the catchment outlet, showed that the concentrations of particulate nitrogen and phosphorus corresponded well to stream flow during the storm, while the nitrate concentration increased on the recession limbs of the hydrographs after the end of the storm. All the synchronous data revealed that nitrate was delivered from the cropped hillslope through subsurface lateral flow to the streams during and after the end of the rainstorms. A chemical mixing model based on electricity conductivity (EC and H+ concentration was successfully established, particularly for the trenched stream. The results showed that the subsurface lateral flow accounted for 29% to 45% of total stream flow in the trenched stream, responsible for 86% of total NO3-N loss (or 26% of total N loss, and for 5.7% to 7.3% of total stream flow at the catchment outlet, responsible for about 69% of total NO3-N loss (or 28% of total N

  20. Effects of soil depth and subsurface flow along the subsurface topography on shallow landslide predictions at the site of a small granitic hillslope

    Science.gov (United States)

    Kim, Min Seok; Onda, Yuichi; Uchida, Taro; Kim, Jin Kwan

    2016-10-01

    Shallow landslides are affected by various conditions, including soil depth and subsurface flow via an increase in the pore water pressure. In this study, we evaluate the effect of soil depth and subsurface flow on shallow landslide prediction using the shallow landslide stability (SHALSTAB) model. Three detailed soil depth data-the average soil depth, weathered soil depth, and bedrock soil depth-were collected using a knocking pole test at a small hillslope site composed of granite in the Republic of Korea. The SHALSTAB model was applied to a ground surface topographic digital elevation model (DEM) using the three soil depths and upslope contributing area (SCA) assuming subsurface flow calculated from four DEMs: a ground surface topography (GSTO) DEM, weathered soil topography (WSTO) DEM, bedrock topography (BSTO) DEM, and low-level bedrock topography (EBSTO) DEM. The model performance was measured using a receiver operating characteristic (ROC) analysis. While evaluating the effect of the soil depth with SCA using GSTO DEM, it was found that the bedrock soil depth had higher prediction accuracy compared to that of the average soil depth or weathered soil depth. To evaluate the saturated subsurface flow between the soil and bedrock, SCAs calculated using WSTO and BSTO DEMs were applied. From these simulations, we found that SCA from BSTO DEM and the bedrock soil depth affect the shallow landslide prediction; however, these prediction effects are not significantly increased by large differences in the elevation (between the lowest and highest elevation values). Therefore, we considered the influence of the bedrock depression and SCA from EBSTO DEM. In applying SCA from EBSTO, the prediction accuracy was significantly increased compared to the other predictions. Our results demonstrate that the influence of the bedrock topography on the prediction of shallow landslides may be particularly significant at the scale of a hillslope.

  1. Improving Ecological Response Monitoring of Environmental Flows

    Science.gov (United States)

    King, Alison J.; Gawne, Ben; Beesley, Leah; Koehn, John D.; Nielsen, Daryl L.; Price, Amina

    2015-05-01

    Environmental flows are now an important restoration technique in flow-degraded rivers, and with the increasing public scrutiny of their effectiveness and value, the importance of undertaking scientifically robust monitoring is now even more critical. Many existing environmental flow monitoring programs have poorly defined objectives, nonjustified indicator choices, weak experimental designs, poor statistical strength, and often focus on outcomes from a single event. These negative attributes make them difficult to learn from. We provide practical recommendations that aim to improve the performance, scientific robustness, and defensibility of environmental flow monitoring programs. We draw on the literature and knowledge gained from working with stakeholders and managers to design, implement, and monitor a range of environmental flow types. We recommend that (1) environmental flow monitoring programs should be implemented within an adaptive management framework; (2) objectives of environmental flow programs should be well defined, attainable, and based on an agreed conceptual understanding of the system; (3) program and intervention targets should be attainable, measurable, and inform program objectives; (4) intervention monitoring programs should improve our understanding of flow-ecological responses and related conceptual models; (5) indicator selection should be based on conceptual models, objectives, and prioritization approaches; (6) appropriate monitoring designs and statistical tools should be used to measure and determine ecological response; (7) responses should be measured within timeframes that are relevant to the indicator(s); (8) watering events should be treated as replicates of a larger experiment; (9) environmental flow outcomes should be reported using a standard suite of metadata. Incorporating these attributes into future monitoring programs should ensure their outcomes are transferable and measured with high scientific credibility.

  2. In situ permeable flow sensor - OST reference No. 99. Subsurface contaminants focus area

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    This summary reports describes the In Situ Permeable Flow Sensor (ISPFS) developed to directly measure the direction and velocity of groundwater flow at a point in saturated soil sediments. The ISPFS provides information for locating, designing, and monitoring waste disposal sites, and for monitoring remediated waste sites. The design and performance are described and compared to alternative methods. Economic, regulatory, and policy issues are discussed. Applicability of the ISPFS to specific situations is also summarized. 8 refs., 7 figs., 3 tabs.

  3. Discharge-nitrate data clustering for characterizing surface-subsurface flow interaction and calibration of a hydrologic model

    Science.gov (United States)

    Shrestha, R. R.; Rode, M.

    2008-12-01

    Concentration of reactive chemicals has different chemical signatures in baseflow and surface runoff. Previous studies on nitrate export from a catchment indicate that the transport processes are driven by subsurface flow. Therefore nitrate signature can be used for understanding the event and pre-event contributions to streamflow and surface-subsurface flow interactions. The study uses flow and nitrate concentration time series data for understanding the relationship between these two variables. Unsupervised artificial neural network based learning method called self organizing map is used for the identification of clusters in the datasets. Based on the cluster results, five different pattern in the datasets are identified which correspond to (i) baseflow, (ii) subsurface flow increase, (iii) surface runoff increase, (iv) surface runoff recession, and (v) subsurface flow decrease regions. The cluster results in combination with a hydrologic model are used for discharge separation. For this purpose, a multi-objective optimization tool NSGA-II is used, where violation of cluster results is used as one of the objective functions. The results show that the use of cluster results as supplementary information for the calibration of a hydrologic model gives a plausible simulation of subsurface flow as well total runoff at the catchment outlet. The study is undertaken using data from the Weida catchment in the North-Eastern Germany, which is a sub-catchment of the Weisse Elster river in the Elbe river basin.

  4. The influence of subsurface flow on lake formation and north polar lake distribution on Titan

    Science.gov (United States)

    Horvath, David G.; Andrews-Hanna, Jeffrey C.; Newman, Claire E.; Mitchell, Karl L.; Stiles, Bryan W.

    2016-10-01

    Observations of lakes, fluvial dissection of the surface, rapid variations in cloud cover, and lake shoreline changes indicate that Saturn's moon Titan is hydrologically active, with a hydrocarbon-based hydrological cycle dominated by liquid methane. Here we use a numerical model to investigate the Titan hydrological cycle - including surface, subsurface, and atmospheric components - in order to investigate the underlying causes of the observed distribution and sizes of lakes in the north polar region. The hydrocarbon-based hydrological cycle is modeled using a numerical subsurface flow model and analytical runoff scheme, driven by a general circulation model with an active methane-cycle. This model is run on synthetically generated topography that matches the fractal character of the observed topography, without explicit representation of the effects of erosion and deposition. At the scale of individual basins, intermediate to high permeability (10-8-10-6 cm2) aquifers are required to reproduce the observed large stable lakes. However, at the scale of the entire north polar lake district, a high permeability aquifer results in the rapid flushing of methane through the aquifer from high polar latitudes to dry lower polar latitudes, where methane is removed by evaporation, preventing large lakes from forming. In contrast, an intermediate permeability aquifer slows the subsurface flow from high polar latitudes, allowing greater lake areas. The observed distribution of lakes is best matched by either a uniform intermediate permeability aquifer, or a combination of a high permeability cap at high latitudes surrounded by an intermediate permeability aquifer at lower latitudes, as could arise due to karstic processes at the north pole. The stability of Kraken Mare further requires reduction of the evaporation rate over the sea to 1% of the value predicted by the general circulation model, likely as a result of dissolved ethane, nitrogen, or organic solutes, and/or a

  5. An Electrode-based approach for monitoring in situ microbial activity during subsurface bioremediation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, K.H.; Nevin, K.P.; Franks, A.; Englert, A.; Long, P.E.; Lovley, D.R.

    2009-11-15

    Current production by microorganisms colonizing subsurface electrodes and its relationship to substrate availability and microbial activity was evaluated in an aquifer undergoing bioremediation. Borehole graphite anodes were installed downgradient from a region of acetate injection designed to stimulate bioreduction of U(VI); cathodes consisted of graphite electrodes embedded at the ground surface. Significant increases in current density ({<=}50 mA/m{sup 2}) tracked delivery of acetate to the electrodes, dropping rapidly when acetate inputs were discontinued. An upgradient control electrode not exposed to acetate produced low, steady currents ({<=}0.2 mA/m{sup 2}). Elevated current was strongly correlated with uranium removal but minimal correlation existed with elevated Fe(II). Confocal laser scanning microscopy of electrodes revealed firmly attached biofilms, and analysis of 16S rRNA gene sequences indicated the electrode surfaces were dominated (67-80%) by Geobacter species. This is the first demonstration that electrodes can produce readily detectable currents despite long-range (6 m) separation of anode and cathode, and these results suggest that oxidation of acetate coupled to electron transfer to electrodes by Geobacter species was the primary source of current. Thus it is expected that current production may serve as an effective proxy for monitoring in situ microbial activity in a variety of subsurface anoxic environments.

  6. Removal of nutrients from septic tank effluent with baffle subsurface-flow constructed wetlands.

    Science.gov (United States)

    Cui, Lihua; Ouyang, Ying; Yang, Weizhi; Huang, Zhujian; Xu, Qiaoling; Yu, Guangwei

    2015-04-15

    Three new baffle flow constructed wetlands (CWs), namely the baffle horizontal flow CW (Z1), baffle vertical flow CW (Z2) and baffle hybrid flow CW (Z3), along with one traditional horizontal subsurface flow CW (Z4) were designed to test the removal efficiency of nitrogen (N) and phosphorus (P) from the septic tank effluent under varying hydraulic retention times (HRTs). Results showed that the optimal HRT was two days for maximal removal of N and P from the septic tank effluent among the four CWs. At this HRT, the Z1, Z2, Z3 and Z4 CWs removed, respectively, 49.93, 58.50, 46.01 and 44.44% of TN as well as 87.82, 93.23, 95.97 and 91.30% of TP. Our study further revealed that the Z3 CW was the best design for overall removal of N and P from the septic tank effluent due to its hybrid flow directions with better oxygen supply inside the CW system.

  7. An iterative stochastic ensemble method for parameter estimation of subsurface flow models

    KAUST Repository

    Elsheikh, Ahmed H.

    2013-06-01

    Parameter estimation for subsurface flow models is an essential step for maximizing the value of numerical simulations for future prediction and the development of effective control strategies. We propose the iterative stochastic ensemble method (ISEM) as a general method for parameter estimation based on stochastic estimation of gradients using an ensemble of directional derivatives. ISEM eliminates the need for adjoint coding and deals with the numerical simulator as a blackbox. The proposed method employs directional derivatives within a Gauss-Newton iteration. The update equation in ISEM resembles the update step in ensemble Kalman filter, however the inverse of the output covariance matrix in ISEM is regularized using standard truncated singular value decomposition or Tikhonov regularization. We also investigate the performance of a set of shrinkage based covariance estimators within ISEM. The proposed method is successfully applied on several nonlinear parameter estimation problems for subsurface flow models. The efficiency of the proposed algorithm is demonstrated by the small size of utilized ensembles and in terms of error convergence rates. © 2013 Elsevier Inc.

  8. Efficiency of a Horizontal Sub-Surface Flow Constructed Wetland Treatment System in an Arid Area

    Directory of Open Access Journals (Sweden)

    Abeer Albalawneh

    2016-02-01

    Full Text Available The main objective of this study was to evaluate the performance and treatment efficiency of the Horizontal Sub-Surface Flow Constructed Wetland treatment system (HSF-CW in an arid climate. Seventeen sub-surface, horizontal-flow HSF-CW units have been operated for approximately three years to improve the quality of partially-treated municipal wastewater. The studied design parameters included two sizes of volcanic tuff media (i.e., fine or coarse, two different bed dimensions (i.e., long and short, and three plantation types (i.e., reed, kenaf, or no vegetation as a control. The effluent Biological Oxygen Demand (BOD5, Chemical Oxygen Demand (COD, Total Suspended Solid (TSS, and phosphorus from all of the treatments were significantly lower as compared to the influent and demonstrated a removal efficiency of 55%, 51%, 67%, and 55%, respectively. There were significant increases in Electrical Conductivity (EC, sulfate, and calcium in the effluent of most HSF-CWs due to evaporative concentration and mineral dissolution from the media. The study suggests that unplanted beds with either fine or coarse media are the most suitable combinations among all of the studied designs based on their treatment efficiency and less water loss in arid conditions.

  9. Intensified nitrate and phosphorus removal in an electrolysis -integrated horizontal subsurface-flow constructed wetland.

    Science.gov (United States)

    Gao, Y; Xie, Y W; Zhang, Q; Wang, A L; Yu, Y X; Yang, L Y

    2017-01-01

    A novel electrolysis-integrated horizontal subsurface-flow constructed wetland system (E-HFCWs) was developed for intensified removal of nitrogen and phosphorus contaminated water. The dynamics of nitrogen and phosphorus removal and that of main water qualities of inflow and outflow were also evaluated. The hydraulic retention time (HRT) greatly enhanced nitrate removal when the electrolysis current intensity was stabilized at 0.07 mA/cm(2). When the HRT ranged from 2 h to 12 h, the removal rate of nitrate increased from 20% to 84%. Phosphorus (P) removal was also greatly enhanced-exceeding 90% when the HRT was longer than 4 h in the electrolysis-integrated HFCWs. This improved P removal is due to the in-situ formation of ferric ions by anodizing of sacrificial iron anodes, causing chemical precipitation, physical adsorption and flocculation of phosphorus. Thus, electrolysis plays an important role in nitrate and phosphorus removal. The diversity and communities of bacteria in the biofilm of substrate was established by the analysis of 16S rDNA gene sequences, and the biofilm was abundant with Comamonadaceae and Xanthomonadaceae bacteria in E-HFCWs. Test results illustrated that the electrolysis integrated with horizontal subsurface-flow constructed wetland is a feasible and effective technology for intensified nitrogen and phosphorus removal. Copyright © 2016. Published by Elsevier Ltd.

  10. A virtual experiment on the effect of canopy and forest floor interception on subsurface flow behaviour

    Science.gov (United States)

    Gerrits, A. M. J.; Hopp, L.; McDonnell, J. J.; Savenije, H. H. G.; Pfister, L.

    2009-04-01

    From several field experiments we know that the soil moisture distribution is highly heterogeneous on a hillslope, and also lateral subsurface flow appears to develop irregular flow paths along its way downslope. However, knowledge is still lacking on which processes are causing this spatial distribution. One of the possible explanations could be interception. First of all, interception prevents a part of the rainfall to infiltrate in the unsaturated zone, which is immediately fed back to the atmosphere. This fast feedback is highly dependent on the vegetation density, and causes a spread in the distribution of the net rainfall. On the other hand, it appears that vegetation can also funnel rain water, causing hot spots of high infiltration. Finally, interception delays precipitation. Only after the interception storage has been filled, water can find its way down through several storages. To investigate the influence of interception on subsurface flow processes, detailed experimental data is required. Because this data is often not available and new or additional field campaigns are very labour intensive, a virtual experiment can be a helpful tool. A virtual experiment is a numerical experiment driven by collective field intelligence. It provides a learning tool to investigate the effect of separated processes in a complex system. We apply the concept of virtual modelling to investigate the effects of interception on subsurface flow processes. It will enable us to separate the effect of ‘no interception', ‘canopy interception only', and ‘both canopy and forest floor interception'. Furthermore, we shall explore if there occurs a change in flow paths patterns when we use lumped or distributed input data. We use the topography characteristics of the Panola hillslope (Georgia, USA). On this hillslope intensive trench and soil moisture measurements have been carried out. Since there are no detailed interception measurements at Panola, we use interception data from

  11. Dual states estimation of a subsurface flow-transport coupled model using ensemble Kalman filtering

    KAUST Repository

    El Gharamti, Mohamad

    2013-10-01

    Modeling the spread of subsurface contaminants requires coupling a groundwater flow model with a contaminant transport model. Such coupling may provide accurate estimates of future subsurface hydrologic states if essential flow and contaminant data are assimilated in the model. Assuming perfect flow, an ensemble Kalman filter (EnKF) can be used for direct data assimilation into the transport model. This is, however, a crude assumption as flow models can be subject to many sources of uncertainty. If the flow is not accurately simulated, contaminant predictions will likely be inaccurate even after successive Kalman updates of the contaminant model with the data. The problem is better handled when both flow and contaminant states are concurrently estimated using the traditional joint state augmentation approach. In this paper, we introduce a dual estimation strategy for data assimilation into a one-way coupled system by treating the flow and the contaminant models separately while intertwining a pair of distinct EnKFs, one for each model. The presented strategy only deals with the estimation of state variables but it can also be used for state and parameter estimation problems. This EnKF-based dual state-state estimation procedure presents a number of novel features: (i) it allows for simultaneous estimation of both flow and contaminant states in parallel; (ii) it provides a time consistent sequential updating scheme between the two models (first flow, then transport); (iii) it simplifies the implementation of the filtering system; and (iv) it yields more stable and accurate solutions than does the standard joint approach. We conducted synthetic numerical experiments based on various time stepping and observation strategies to evaluate the dual EnKF approach and compare its performance with the joint state augmentation approach. Experimental results show that on average, the dual strategy could reduce the estimation error of the coupled states by 15% compared with the

  12. Optimal Control of Partially Miscible Two-Phase Flow with Applications to Subsurface CO2 Sequestration

    KAUST Repository

    Simon, Moritz

    2013-01-01

    Motivated by applications in subsurface CO2 sequestration, we investigate constrained optimal control problems with partially miscible two-phase flow in porous media. The objective is, e.g., to maximize the amount of trapped CO2 in an underground reservoir after a fixed period of CO2 injection, where the time-dependent injection rates in multiple wells are used as control parameters. We describe the governing two-phase two-component Darcy flow PDE system and formulate the optimal control problem. For the discretization we use a variant of the BOX method, a locally conservative control-volume FE method. The timestep-wise Lagrangian of the control problem is implemented as a functional in the PDE toolbox Sundance, which is part of the HPC software Trilinos. The resulting MPI parallelized Sundance state and adjoint solvers are linked to the interior point optimization package IPOPT. Finally, we present some numerical results in a heterogeneous model reservoir.

  13. A coupled surface/subsurface flow model accounting for air entrapment and air pressure counterflow

    DEFF Research Database (Denmark)

    Delfs, Jens Olaf; Wang, Wenqing; Kalbacher, Thomas

    2013-01-01

    This work introduces the soil air system into integrated hydrology by simulating the flow processes and interactions of surface runoff, soil moisture and air in the shallow subsurface. The numerical model is formulated as a coupled system of partial differential equations for hydrostatic (diffusive...... algorithm, leakances operate as a valve for gas pressure in a liquid-covered porous medium facilitating the simulation of air out-break events through the land surface. General criteria are stated to guarantee stability in a sequential iterative coupling algorithm and, in addition, for leakances to control...... the mass exchange between compartments. A benchmark test, which is based on a classic experimental data set on infiltration excess (Horton) overland flow, identified a feedback mechanism between surface runoff and soil air pressures. Our study suggests that air compression in soils amplifies surface runoff...

  14. Monitoring And Controlling Hydroponic Flow

    Science.gov (United States)

    Dreschel, Thomas W.

    1992-01-01

    Pressure-monitoring and -controlling apparatus maintains slight suction required on nutrient solution in apparatus described in "Tubular Membrane Plant-Growth Unit" (KSC-11375), while overcoming gravity effects on operation of system on Earth. Suction helps to hold solution in tubular membrane.

  15. Poroelastic responses of confined aquifers to subsurface strain changes and their use for volcano monitoring

    Directory of Open Access Journals (Sweden)

    K. Strehlow

    2015-06-01

    Two different aquifers are invoked – an unconsolidated pyroclastic deposit and a vesicular lava flow – and embedded in an impermeable crust, overlying a magma chamber. The time-dependent, fully coupled models simulate crustal deformation accompanying chamber pressurisation and the resulting hydraulic head changes as well as porous flow in the aquifer. The simulated deformational strain leads to centimetres (pyroclastic aquifer to meters (lava flow aquifer of hydraulic head changes; both strain and hydraulic head change with time due to substantial porous flow in the hydrological system. Well level changes are particularly sensitive to chamber volume and shape, followed by chamber depth and the phase of the pore fluid. The Young's Modulus and permeability of the aquifer, as well as the strength of pressurisation also have significant influence on the hydraulic head signal. While source characteristics, the distance between chamber and aquifer and the elastic stratigraphy determine the strain field and its partitioning, flow and coupling parameters define how the aquifer responds to this strain and how signals change with time. We investigated a period of pre-eruptive head changes recorded at Usu volcano, Japan, where well data were interpreted using an analytical deformation model. We find that generic analytical models can fail to capture the complex pre-eruptive subsurface mechanics leading to well level changes, due to aquifer pressure changes being sensitive to chamber shape and lithological heterogeneities. In addition, the presence of a pore fluid and its flow have a significant influence on the strain signal in the aquifer and are commonly neglected in analytical models. These findings highlight the need for numerical models for the interpretation of observed well level signals. However, simulated water table changes do mirror volumetric strain and wells can therefore serve as comparatively cheap strain meters that could provide important insights into

  16. Acoustic Flow Monitor System - User Manual

    Science.gov (United States)

    LaHusen, Richard

    2005-01-01

    INTRODUCTION The Acoustic Flow Monitor (AFM) is a portable system that was designed by the U.S. Geological Survey Cascades Volcano Observatory to detect and monitor debris flows associated with volcanoes. It has been successfully used internationally as part of real-time warning systems in valleys threatened by such flows (Brantley, 1990; Marcial and others, 1996; Lavigne and others, 2000). The AFM system has also been proven to be an effective tool for monitoring some non-volcanic debris flows. This manual is intended to serve as a basic guide for the installation, testing, and maintenance of AFM systems. An overview of how the system works, as well as instructions for installation and guidelines for testing, is included. Interpretation of data is not covered in this manual; rather, the user should refer to the references provided for published examples of AFM data.

  17. Laboratory and numerical evaluation of borehole methods for subsurface horizontal flow characterization.

    Energy Technology Data Exchange (ETDEWEB)

    Pedler, William H. (Radon Abatement Systems, Inc., Golden, CO); Jepsen, Richard Alan (Sandia National Laboratories, Carlsbad, NM)

    2003-08-01

    The requirement to accurately measure subsurface groundwater flow at contaminated sites, as part of a time and cost effective remediation program, has spawned a variety of flow evaluation technologies. Validation of the accuracy and knowledge regarding the limitations of these technologies are critical for data quality and application confidence. Leading the way in the effort to validate and better understand these methodologies, the US Army Environmental Center has funded a multi-year program to compare and evaluate all viable horizontal flow measurement technologies. This multi-year program has included a field comparison phase, an application of selected methods as part of an integrated site characterization program phase, and most recently, a laboratory and numerical simulator phase. As part of this most recent phase, numerical modeling predictions and laboratory measurements were made in a simulated fracture borehole set-up within a controlled flow simulator. The scanning colloidal borescope flowmeter (SCBFM) and advanced hydrophysical logging (NxHpL{trademark}) tool were used to measure velocities and flow rate in a simulated fractured borehole in the flow simulator. Particle tracking and mass flux measurements were observed and recorded under a range of flow conditions in the simulator. Numerical models were developed to aid in the design of the flow simulator and predict the flow conditions inside the borehole. Results demonstrated that the flow simulator allowed for predictable, easily controlled, and stable flow rates both inside and outside the well. The measurement tools agreed well with each other over a wide range of flow conditions. The model results demonstrate that the Scanning Colloidal Borescope did not interfere with the flow in the borehole in any of the tests. The model is capable of predicting flow conditions and agreed well with the measurements and observations in the flow simulator and borehole. Both laboratory and model results showed a

  18. Subsurface hydrological information in rock-slide phenomena from groundwater spring monitoring.

    Science.gov (United States)

    Rochetti, Francesco; Corsini, Alessandro; Deiana, Manuela; Loche, Roberto; Mulas, Marco; Russo, Michele

    2016-04-01

    Frequently rock-slide phenomena are characterized by rough topography and high declivity of the slope. Due to these characteristics, the drilling of boreholes is not so common and in some circumstance expensive. Consequently, the exact information about depth of the sliding surface and about groundwater processes, groundwater levels or pore water pressure distribution are missing. Alternately, some information about the groundwater can be obtained from the physical-chemical monitoring of springs. The research highlights preliminary results, about the groundwater processes, obtained from the continuous flow-rate monitoring of a spring located in the active Piagneto rock-slide (northern Apennine). The spring has been monitored from Sept-2014 until Oct-2015 using a piezometer transducer (sampling frequency 1 h) and a triangular weir. The landslide was monitored in continuous since the 2009 using an automatic total station and some reflectors. The monitoring of the rock-slide displacements showed creep phenomena in the summer and acceleration phases from autumn to late spring, during periods characterized by high rainfall intensity; rainfall with intensity higher than 10 mm/d and duration less than 15 days can produce the acceleration of the sliding mass. Before 2014 any information about groundwater was collected. The successively spring monitoring shows the follow results: the spring flow rate is strongly variable in the time; only some rainfall events, with particular intensity and duration (generally total amount higher than 100 mm), are responsible of strong changes in the flow rate, and the flow rate starts to increase only after some hours; the snow melting events, also when there is a fast reduction of the snow thickness, don't produce high variation in the flow rate discharge; there is a strong correlation between the flow rate peaks and the rock-slide acceleration; an infiltration coefficient higher than 70% is estimated through the comparison between the

  19. Limestone and Zeolite as Alternative Media in Horizontal Subsurface Flow Constructed Wetlands: Laboratory-Scale Studies

    Science.gov (United States)

    Lizama, K.; Jaque, I.; Ayala, J.

    2016-12-01

    Arsenic is well known for its chronic toxicity. Millions of people around the world are currently at risk, drinking water with As concentrations above 10 ppb, the WHO drinking water guideline. Although different treatment options exist, they are often limited by elevated costs and maintenance requirements. Constructed wetlands are a natural water treatment system, capable to remove metals and metalloids -including As- via different physical, chemical and biological processes. The use of alternative supporting media to enhance As removal in subsurface flow wetlands has been recommended, but not sufficiently studied. Limestone and zeolite have been identified as effective supporting media in subsurface flow wetlands aiming As removal. However, there are still key aspects to be addressed, such as the implications of using these media, the speciation in the solid phase, the role of vegetation, etc. This study investigated the performance of limestone and zeolite in three types of experiments: batch, column and as main supporting media in a bench scale horizontal subsurface flow wetland system. Synthetic water resembling a contaminated river in Chile (As concentration=3 mg/L, Fe concentration= 100 mg/L, pH=2) was used in all experiments. In the batch experiments, the As concentration, the mass of media and the contact time were varied. The column system consisted of three limestone columns and three zeolite columns, operated under a hydraulic loading of 20 mm/d. The wetland system consisted of twelve PVC cells: six filled with zeolite and six with limestone. Phragmites australis were planted in three cells of each media type, as control cells. From the batch experiments, maximum As sorption capacities as indicated by Langmuir model were 1.3 mg/g for limestone and 0.17 mg/g for zeolite, at 18 h contact time and 6.3 g/L medium concentration. EDS and XPS analyses revealed that As and Fe were retained in zeolite at the end of the batch experiments. Zeolite and limestone

  20. Evaluation of a Heterogeneity Preserving Inversion Method for Subsurface Unsaturated Flow

    Science.gov (United States)

    Zhang, Y.; Schaap, M. G.; Neuman, S. P.; Guadagnini, A.; Riva, M.

    2013-12-01

    Natural recharge to groundwater in semi-arid regions is driven by unsaturated flow through an often deep vadose zone. Understanding and modeling such flow requires knowledge of the subsurface heterogeneity of hydraulic properties. It is expensive and labor intensive to measure such properties, making it necessary to rely on other sources of information. Pedotransfer functions (PTFs) constitute cheap and viable tools to estimate hydraulic properties from soil or sediment texture. Due to the predominantly empirical nature of PTFs and the fact that PTFs are often based on data derived from small laboratory samples, biased estimates of hydraulic parameters may be produced that would likely bias modeled field scale deep vadose zone flow. In this work, an inversion framework that treats the subsurface as a composite medium formed by different zones, each associated with spatially heterogeneous hydraulic parameters, is developed to allow (a) preserving the details of the subsurface heterogeneous nature and (b) assuring consistency among hydraulic parameters associated with different regions of the domain. The approach is demonstrated through a field application, which considers the Maricopa site near Phoenix, Arizona. The study site is a 50x50 meter and 15 meter deep vadose zone at which a 28-day constant-rate infiltration experiment was conducted in 2001. Moisture content at the site was measured daily with neutron thermalization at 400 locations during the infiltration period, and at irregular intervals 100 and 200 days prior and after infiltration, respectively. A PTF based on the Rosetta model is applied on the basis of measured spatial distributions of textural and bulk density data to provide initial estimates of the three-dimensional structure of hydraulic properties. Simple linear functions are defined that transform the PTF estimates of soil hydraulic properties values into hydraulic parameters that minimize the objective functions for the domain, while zonation

  1. Surrogate model based iterative ensemble smoother for subsurface flow data assimilation

    Science.gov (United States)

    Chang, Haibin; Liao, Qinzhuo; Zhang, Dongxiao

    2017-02-01

    Subsurface geological formation properties often involve some degree of uncertainty. Thus, for most conditions, uncertainty quantification and data assimilation are necessary for predicting subsurface flow. The surrogate model based method is one common type of uncertainty quantification method, in which a surrogate model is constructed for approximating the relationship between model output and model input. Based on the prediction ability, the constructed surrogate model can be utilized for performing data assimilation. In this work, we develop an algorithm for implementing an iterative ensemble smoother (ES) using the surrogate model. We first derive an iterative ES scheme using a regular routine. In order to utilize surrogate models, we then borrow the idea of Chen and Oliver (2013) to modify the Hessian, and further develop an independent parameter based iterative ES formula. Finally, we establish the algorithm for the implementation of iterative ES using surrogate models. Two surrogate models, the PCE surrogate and the interpolation surrogate, are introduced for illustration. The performances of the proposed algorithm are tested by synthetic cases. The results show that satisfactory data assimilation results can be obtained by using surrogate models that have sufficient accuracy.

  2. Deformation band clusters on Mars and implications for subsurface fluid flow

    Science.gov (United States)

    Okubo, C.H.; Schultz, R.A.; Chan, M.A.; Komatsu, G.

    2009-01-01

    High-resolution imagery reveals unprecedented lines of evidence for the presence of deformation band clusters in layered sedimentary deposits in the equatorial region of Mars. Deformation bands are a class of geologic structural discontinuity that is a precursor to faults in clastic rocks and soils. Clusters of deformation bands, consisting of many hundreds of individual subparallel bands, can act as important structural controls on subsurface fluid flow in terrestrial reservoirs, and evidence of diagenetic processes is often preserved along them. Deformation band clusters are identified on Mars based on characteristic meter-scale architectures and geologic context as observed in data from the High-Resolution Imaging Science Experiment (HiRISE) camera. The identification of deformation band clusters on Mars is a key to investigating the migration of fluids between surface and subsurface reservoirs in the planet's vast sedimentary deposits. Similar to terrestrial examples, evidence of diagenesis in the form of light- and dark-toned discoloration and wall-rock induration is recorded along many of the deformation band clusters on Mars. Therefore, these structures are important sites for future exploration and investigations into the geologic history of water and water-related processes on Mars. ?? 2008 Geological Society of America.

  3. Applying Process-Based Models for Subsurface Flow Treatment Wetlands: Recent Developments and Challenges

    Directory of Open Access Journals (Sweden)

    Guenter Langergraber

    2016-12-01

    Full Text Available To date, only few process-based models for subsurface flow treatment wetlands have been developed. For modelling a treatment wetland, these models have to comprise a number of sub-models to describe water flow, pollutant transport, pollutant transformation and degradation, effects of wetland plants, and transport and deposition of suspended particulate matter. The two most advanced models are the HYDRUS Wetland Module and BIO-PORE. These two models are briefly described. This paper shows typical simulation results for vertical flow wetlands and discusses experiences and challenges using process-based wetland models in relation to the sub-models describing the most important wetland processes. It can be demonstrated that existing simulation tools can be applied for simulating processes in treatment wetlands. Most important for achieving a good match between measured and simulated pollutant concentrations is a good calibration of the water flow and transport models. Only after these calibrations have been made and the effect of the influent fractionation on simulation results has been considered, should changing the parameters of the biokinetic models be taken into account. Modelling the effects of wetland plants is possible and has to be considered when important. Up to now, models describing clogging are the least established models among the sub-models required for a complete wetland model and thus further development and research is required.

  4. Modelling and evaluation of nitrogen removal performance in subsurface flow and free water surface constructed wetlands.

    Science.gov (United States)

    Tunçsiper, B; Ayaz, S C; Akça, L

    2006-01-01

    With the aim of protecting drinking water sources in rural regions, pilot-scale subsurface water flow (SSF) and free water surface flow (FWS) constructed wetland systems were evaluated for removal efficiencies of nitrogenous pollutants in tertiary stage treated wastewaters (effluent from the Pasaköy biological nutrient removal plant). Five different hydraulic application rates and emergent (Canna, Cyperus, Typhia sp., Phragmites sp., Juncus, Poaceae, Paspalum and Iris) and floating (Pistia, Salvina and Lemna) plant species were assayed. The average annual NH4-N, NO3-N and organic-N treatment efficiencies were 81, 40 and 74% in SSFs and 76, 59 and 75% in FWSs, respectively. Two types of the models (first-order plug flow and multiple regression) were tried to estimate the system performances. Nitrification, denitrification and ammonification rate constants (k20) values in SSF and FWS systems were 0.898 d-1 and 0.541 d(-1), 0.486 d(-1) and 0.502 d(-1), 0.986 d(-1) and 0.908, respectively. Results show that the first-order plug flow model clearly estimates slightly higher or lower values than observed when compared with the other model.

  5. Effect of dosing regime on nitrification in a subsurface vertical flow treatment wetland system.

    Science.gov (United States)

    Kantawanichkul, Suwasa; Boontakhum, Walaya

    2012-01-01

    In this study, the effect of dosing regime on nitrification in a subsurface vertical flow treatment wetland system was investigated. The experimental unit was composed of four circular concrete tanks (1 m diameter and 80 cm deep), filled with gravel (1-2 cm) and planted with Cyperus alternifolius L. Synthetic wastewater with average chemical oxygen demand (COD) and ammonia nitrogen of 1,151 and 339 mg/L was fed into each tank. Different feeding and resting periods were applied: continuous flow (tank 1), 4 hrs on and 4 hrs off (tank 2), 1 hr on and 3 hrs off (tank 3) and 15 minutes on and 3 hrs 45 minutes off (tank 4). All four tanks were under the same hydraulic loading rate of 5 cm/day. After 165 days the reduction of total Kjeldahl nitrogen and ammonia nitrogen and the increase of nitrate nitrogen were greatest in tank 4, which had the shortest feeding period, while the continuous flow produced the lowest results. Effluent tanks 2 and 3 experienced similar levels of nitrification, both higher than that of tank 1. Thus supporting the idea that rapid dosing periods provide better aerobic conditions resulting in enhanced nitrification within the bed. Tank 4 had the highest removal rates for COD, and the continuous flow had the lowest. Tank 2 also exhibited a higher COD removal rate than tank 3, demonstrating that short dosing periods provide better within-bed oxidation and therefore offer higher removal efficiency.

  6. Integration of Genome-Scale Metabolic Nodels of Iron-Reducing Bacteria With Subsurface Flow and Geochemical Reactive Transport Models

    Science.gov (United States)

    Scheibe, T. D.; Mahadevan, R.; Fang, Y.; Garg, S.; Long, P. E.; Lovley, D. M.

    2008-12-01

    Several field and laboratory experiments have demonstrated that the growth and activity of iron-reducing bacteria can be stimulated in many subsurface environments by amendment of groundwater with a soluble electron donor. Under strong iron-reducing conditions, these organisms mediate reactions that can impact a wide range of subsurface contaminants including chlorinated hydrocarbons, metals, and radionuclides. Therefore there is strong interest in in-situ bioremediation as a potential technology for cleanup of contaminated aquifers. To evaluate and design bioremediation systems, as well as to evaluate the viability of monitored natural attenuation as an alternative, quantitative models of biogeochemically reactive transport are needed. To date, most such models represent microbial activity in terms of kinetic rate (e.g., Monod- type) formulations. Such models do not account for fundamental changes in microbial functionality (such as utilization of alternative respiratory pathways) that occur as the result of spatial and temporal variations in the geochemical environment experienced by microorganisms. Constraint-based genome-scale in silico models of microbial metabolism present an alternative to simplified rate formulations that provide flexibility to account for changes in microbial function in response to local geochemical conditions. We have developed and applied a methodology for coupling a constraint-based in silico model of Geobacter sulfurreducens with a conventional model of groundwater flow, transport, and geochemical reaction. Two uses of the in silico model are tested: 1) incorporation of modified microbial growth yield coefficients based on the in silico model, and 2) variation of reaction rates in a reactive transport model based on in silico modeling of a range of local geochemical conditions. Preliminary results from this integrated model will be presented.

  7. Flow and transport processes in a macroporous subsurface-drained glacial till soil

    DEFF Research Database (Denmark)

    Villholth, Karen Grothe; Jensen, Karsten Høgh; Fredericia, Johnny

    1998-01-01

    The qualitative and quantitative effects of macropore flow and transport in an agricultural subsurface-drained glacial till soil in eastern Denmark have been investigated. Three controlled tracer experiments on individual field plots (each approximately 1000 m(2)) were carried out by surface...... was evidenced directly by the rapid (within 10 mm of water input) and abrupt chloride breakthrough in the drainage water at 1.2 m depth in two of the tracer experiments. In the third experiment, the effect of macropore transport was obvious from the rapid and relatively deep penetration of the tracer...... into the soil profile. Dye infiltration experiments in the field as well as in the laboratory supported the recognition of the dominant contribution of macropores to the infiltration and transport process. The soil matrix significantly influenced the tracer distribution by acting as a source or sink...

  8. Model-based design of horizontal subsurface flow constructed treatment wetlands: a review.

    Science.gov (United States)

    Rousseau, Diederik P L; Vanrolleghem, Peter A; De Pauw, Niels

    2004-03-01

    The increasing application of constructed wetlands for wastewater treatment coupled with increasingly strict water quality standards is an ever growing incentive for the development of better process design tools. This paper reviews design models for horizontal subsurface flow constructed treatment wetlands, ranging from simple rules of thumb and regression equations, to the well-known first-order k-C* models, Monod-type equations and more complex dynamic, compartmental models. Especially highlighted in this review are the model constraints and parameter uncertainty. A case study has been used to demonstrate the model output variability and to unravel whether or not more complex but also less manageable models offer a significant advantage to the designer.

  9. Clustered iterative stochastic ensemble method for multi-modal calibration of subsurface flow models

    KAUST Repository

    Elsheikh, Ahmed H.

    2013-05-01

    A novel multi-modal parameter estimation algorithm is introduced. Parameter estimation is an ill-posed inverse problem that might admit many different solutions. This is attributed to the limited amount of measured data used to constrain the inverse problem. The proposed multi-modal model calibration algorithm uses an iterative stochastic ensemble method (ISEM) for parameter estimation. ISEM employs an ensemble of directional derivatives within a Gauss-Newton iteration for nonlinear parameter estimation. ISEM is augmented with a clustering step based on k-means algorithm to form sub-ensembles. These sub-ensembles are used to explore different parts of the search space. Clusters are updated at regular intervals of the algorithm to allow merging of close clusters approaching the same local minima. Numerical testing demonstrates the potential of the proposed algorithm in dealing with multi-modal nonlinear parameter estimation for subsurface flow models. © 2013 Elsevier B.V.

  10. Hybrid nested sampling algorithm for Bayesian model selection applied to inverse subsurface flow problems

    Energy Technology Data Exchange (ETDEWEB)

    Elsheikh, Ahmed H., E-mail: aelsheikh@ices.utexas.edu [Institute for Computational Engineering and Sciences (ICES), University of Texas at Austin, TX (United States); Institute of Petroleum Engineering, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Wheeler, Mary F. [Institute for Computational Engineering and Sciences (ICES), University of Texas at Austin, TX (United States); Hoteit, Ibrahim [Department of Earth Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal (Saudi Arabia)

    2014-02-01

    A Hybrid Nested Sampling (HNS) algorithm is proposed for efficient Bayesian model calibration and prior model selection. The proposed algorithm combines, Nested Sampling (NS) algorithm, Hybrid Monte Carlo (HMC) sampling and gradient estimation using Stochastic Ensemble Method (SEM). NS is an efficient sampling algorithm that can be used for Bayesian calibration and estimating the Bayesian evidence for prior model selection. Nested sampling has the advantage of computational feasibility. Within the nested sampling algorithm, a constrained sampling step is performed. For this step, we utilize HMC to reduce the correlation between successive sampled states. HMC relies on the gradient of the logarithm of the posterior distribution, which we estimate using a stochastic ensemble method based on an ensemble of directional derivatives. SEM only requires forward model runs and the simulator is then used as a black box and no adjoint code is needed. The developed HNS algorithm is successfully applied for Bayesian calibration and prior model selection of several nonlinear subsurface flow problems.

  11. Performance of a subsurface-flow constructed wetland in Southern China

    Institute of Scientific and Technical Information of China (English)

    SHI Lei; WANG Bao-zhen; CAO Xiang-dong; Wang Jin; LEI Zhi-hong; WANG Zhi-ren; LIU Zheng-ying; LU Bing-nan

    2004-01-01

    The operational performance of a full-scale subsurface-flow constructed wetland, which treated the mixed industrial and domestic wastewater with BOD5/COD mean ratio of 0.33 at Shatian, Shenzhen City was studied. The constructed wetland system consists of screens, sump, pumping station, and primary settling basin, facultative pond, first stage wetland and secondary stage wetland. The designed treatment capacity is 5000 m3/d, and the actual influent flow is in the range of 10000 m3/d. Under normal operational conditions, the final effluent quality well met the National Integrated Wastewater Discharge Standard(GB 8978-1996), with the following parameters(mean values): COD 33.90 mg/L, BOD5 7.65 mg/L, TSS 7.92 mg/L, TN 9.11 mg/L and TP 0.56 mg/L. Seven species of plants were selected to grow in the wetland: Reed, Sweetcane flower Silvergrass, Great Bulrush, Powdery Thalia and Canna of three colours. The growing season is a whole year-round. The seasonal discrepancy could be observed and the plants growing in the wetland are vulnerable to lower temperature in winter.The recycling of the effluent in the first stage of the wetland system is an effective measure to improve the performance of the wetland system. The insufficient DO value in the wetland system not only had significant effect on pollutants removal in the wetland, but also was unfavourable to plant growth. The recycling of effluent to the inlet of wetland system and artificial pond to increase DO value of influent to the wetland is key to operate the subsurface constructed wetland steadily and effectively.

  12. Subsurface Multiphase Flow and Multicomponent Reactive Transport Modeling using High-Performance Computing

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, Glenn E.; Lichtner, Peter C.; Lu, Chuan

    2007-08-01

    Numerical modeling has become a critical tool to the Department of Energy for evaluating the environmental impact of alternative energy sources and remediation strategies for legacy waste sites. Unfortunately, the physical and chemical complexity of many sites overwhelms the capabilities of even most “state of the art” groundwater models. Of particular concern are the representation of highly-heterogeneous stratified rock/soil layers in the subsurface and the biological and geochemical interactions of chemical species within multiple fluid phases. Clearly, there is a need for higher-resolution modeling (i.e. more spatial, temporal, and chemical degrees of freedom) and increasingly mechanistic descriptions of subsurface physicochemical processes. We present research being performed in the development of PFLOTRAN, a parallel multiphase flow and multicomponent reactive transport model. Written in Fortran90, PFLOTRAN is founded upon PETSc data structures and solvers and has exhibited impressive strong scalability on up to 4000 processors on the ORNL Cray XT3. We are employing PFLOTRAN in the simulation of uranium transport at the Hanford 300 Area, a contaminated site of major concern to the Department of Energy, the State of Washington, and other government agencies where overly-simplistic historical modeling erroneously predicted decade removal times for uranium by ambient groundwater flow. By leveraging the billions of degrees of freedom available through high-performance computation using tens of thousands of processors, we can better characterize the release of uranium into groundwater and its subsequent transport to the Columbia River, and thereby better understand and evaluate the effectiveness of various proposed remediation strategies.

  13. The value of "black-box" neural network modeling in subsurface flow prediction

    Science.gov (United States)

    Paleologos, E.; Skitzi, I.; Katsifarakis, K.

    2012-04-01

    In several hydrologic cases the complexity of the processes involved tied in with the uncertainty in the subsurface geologic environment, geometries, and boundary conditions cannot be addressed by constitutive relationships, either in a deterministic or a stochastic framework. "Black-box" models are used routinely in surface hydrologic predictions, but in subsurface hydrology there is still a tendency to rely on physical descriptions, even in problems where the geometry, the medium, the processes, the boundary conditions are largely unknown. Subsurface flow in karstic environments exemplifies all the above complexities and uncertainties rendering the use of physical models impractical. The current study uses neural networks to exemplify that "black-box" models can provide useful predictions even in the absence of physical process descriptions. Daily discharges of two springs lying in a karstic environment were simulated for a period of two and a half years with the use of a multi-layer perceptron back-propagation neural network. Missing discharge values were supplemented by assuming linear relationships during base flow conditions, thus extending the length of the data record during the network's training phase and improving its performance. The time lag between precipitation and spring discharge differed significantly for the two springs indicating that in karstic environments hydraulic behavior is dominated, even within a few hundred meters, by local conditions. Optimum training results were attained with a Levenberg-Marquardt algorithm resulting in a network architecture consisting of two input layer neurons, four hidden layer neurons, and one output layer neuron, the spring's discharge. The neural network's predictions captured the behavior for both springs and followed very closely the discontinuities in the discharge time series. Under/over-estimation of observed discharges for the two springs remained below 3%, with the exception of a few local maxima where

  14. A locally conservative stabilized continuous Galerkin finite element method for two-phase flow in poroelastic subsurfaces

    Science.gov (United States)

    Deng, Q.; Ginting, V.; McCaskill, B.; Torsu, P.

    2017-10-01

    We study the application of a stabilized continuous Galerkin finite element method (CGFEM) in the simulation of multiphase flow in poroelastic subsurfaces. The system involves a nonlinear coupling between the fluid pressure, subsurface's deformation, and the fluid phase saturation, and as such, we represent this coupling through an iterative procedure. Spatial discretization of the poroelastic system employs the standard linear finite element in combination with a numerical diffusion term to maintain stability of the algebraic system. Furthermore, direct calculation of the normal velocities from pressure and deformation does not entail a locally conservative field. To alleviate this drawback, we propose an element based post-processing technique through which local conservation can be established. The performance of the method is validated through several examples illustrating the convergence of the method, the effectivity of the stabilization term, and the ability to achieve locally conservative normal velocities. Finally, the efficacy of the method is demonstrated through simulations of realistic multiphase flow in poroelastic subsurfaces.

  15. Microbial monitoring during CO2 storage in deep subsurface saline aquifers in Ketzin, Germany

    Science.gov (United States)

    Wuerdemann, H.; Wandrey, M.; Fischer, S.; Zemke, K.; Let, D.; Zettlitzer, M.; Morozova, D.

    2010-12-01

    Investigations on subsurface saline aquifers have shown an active biosphere composed of diverse groups of microorganisms in the subsurface. Since microorganisms represent very effective geochemical catalysts, they may influence the process of CO2 storage significantly. In the frames of the EU Project CO2SINK a field laboratory to study CO2 storage into saline aquifer was operated. Our studies aim at monitoring of biological and biogeochemical processes and their impact on the technical effectiveness of CO2 storage technique. The interactions between microorganisms and the minerals of both the reservoir and the cap rock may cause changes to the structure and chemical composition of the rock formations, which may influence the reservoir permeability locally. In addition, precipitation and corrosion may be induced around the well affecting the casing and the casing cement. Therefore, analyses of the composition of microbial communities and its changes should contribute to an evaluation of the effectiveness and reliability of the long-term CO2 storage technique. In order to investigate processes in the deep biosphere caused by the injection of supercritical CO2, genetic fingerprinting (PCR SSCP Single-Strand-Conformation Polymorphism) and FISH (Fluorescence in situ Hybridisation) were used for identification and quantification of microorganisms. Although saline aquifers could be characterised as an extreme habitat for microorganisms due to reduced conditions, high pressure and salinity, a high number of diverse groups of microorganisms were detected with downhole sampling in the injection and observation wells at a depth of about 650m depth. Of great importance was the identification of the sulphate reducing bacteria, which are known to be involved in corrosion processes. Microbial monitoring during CO2 injection has shown that both quantity and diversity of microbial communities were strongly influenced by the CO2 injection. In addition, the indigenous microbial

  16. Pollutant removal from municipal wastewater employing baffled subsurface flow and integrated surface flow-floating treatment wetlands.

    Science.gov (United States)

    Saeed, Tanveer; Al-Muyeed, Abdullah; Afrin, Rumana; Rahman, Habibur; Sun, Guangzhi

    2014-04-01

    This article reports pollutant removal performances of baffled subsurface flow, and integrated surface flow-floating treatment wetland units, when arranged in series for the treatment of municipal wastewater in Bangladesh. The wetland units (of the hybrid system) included organic, inorganic media, and were planted with nineteen types of macrophytes. The wetland train was operated under hydraulic loading fluctuation and seasonal variation. The performance analyses (across the wetland units) illustrated simultaneous denitrification and organics removal rates in the first stage vertical flow wetland, due to organic carbon leaching from the employed organic media. Higher mean organics removal rates (656.0 g COD/(m(2)·day)) did not completely inhibit nitrification in the first stage vertical flow system; such pattern could be linked to effective utilization of the trapped oxygen, as the flow was directed throughout the media by the baffle walls. Second stage horizontal flow wetland showed enhanced biodegradable organics removal, which depleted organic carbon availability for denitrification. The final stage integrated wetland system allowed further nitrogen removal from wastewater, via nutrient uptake by plant roots (along with nitrification), and generation of organic carbon (by the dead macrophytes) to support denitrification. The system achieved higher E. coli mortality through protozoa predation, E. coli oxidation, and destruction by UV radiation. In general, enhanced pollutant removal efficiencies as demonstrated by the structurally modified hybrid wetland system signify the necessity of such modification, when operated under adverse conditions such as: substantial input organics loading, hydraulic loading fluctuation, and seasonal variation. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  17. COUPLING SIMULATION OF SURFACE FLOW AND SUBSURFACE FLOW OVER POROUS MEDIA

    Institute of Scientific and Technical Information of China (English)

    ZHANG Pei-wen; LIU De-fu; SONG Yu-pu

    2004-01-01

    Mathematical model of water flow over porous media is developed, the computer program is compiled ,and an example is given to verify the validity of the model. The results of the calculation show that the model is very useful and worth going further study in practical engineering.

  18. Modelling bioclogging in variably saturated porous media and the interactions between surface/subsurface flows: Application to Constructed Wetlands.

    Science.gov (United States)

    Samsó, Roger; García, Joan; Molle, Pascal; Forquet, Nicolas

    2016-01-01

    Horizontal subsurface Flow Constructed Wetlands (HF CWs) are biofilters planted with aquatic macrophytes within which wastewater is treated mostly through contact with bacterial biofilms. The high concentrations of organic carbon and nutrients being transported leads to high bacterial biomass production, which decreases the flow capacity of the porous material (bioclogging). In severe bioclogging scenarios, overland flow may take place, reducing overall treatment performance. In this work we developed a mathematical model using COMSOL Multiphysics™ and MATLAB(®) to simulate bioclogging effects in HF CWs. Variably saturated subsurface flow and overland flow were described using the Richards equation. To simplify the inherent complexity of the processes involved in bioclogging development, only one bacterial group was considered, and its growth was described using a Monod equation. Bioclogging effects on the hydrodynamics were taken into account by using a conceptual model that affects the value of Mualem's unsaturated relative permeability. Simulation results with and without bioclogging were compared to showcase the impact of this process on the overall functioning of CWs. The two scenarios rendered visually different bacteria distributions, flow and transport patterns, showing the necessity of including bioclogging effects on CWs models. This work represents one of the few studies available on bioclogging in variably saturated conditions, and the presented model allows simulating the interaction between overland and subsurface flow occurring in most HF CWs. Hence, this work gets us a step closer to being able to describe CWs functioning in an integrated way using mathematical models. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Storing Data Flow Monitoring in Hadoop

    CERN Document Server

    Georgiou, Anastasia

    2013-01-01

    The on-line data flow monitoring for the CMS data acquisition system produces a large amount of data. Only 5% of data is stored permanently in a relational database due to performance issues and the cost for using dedicated infrastructure (e.g. Oracle systems). In a commercial environment, companies and organizations need to find new innovative approaches to process such big volumes of data, known as “big data”. The Big Data approach is trying to address the problem of a large and complex collection of data sets that become difficult to handle using traditional data processing applications. Using these new technologies, it should be possible to store all the monitoring information for a time window of months or a year. This report contains an initial evaluation of Hadoop for storage of data flow monitoring and subsequent data mining.

  20. Monitoring radionuclides in subsurface drinking water sources near unconventional drilling operations: a pilot study.

    Science.gov (United States)

    Nelson, Andrew W; Knight, Andrew W; Eitrheim, Eric S; Schultz, Michael K

    2015-04-01

    Unconventional drilling (the combination of hydraulic fracturing and horizontal drilling) to extract oil and natural gas is expanding rapidly around the world. The rate of expansion challenges scientists and regulators to assess the risks of the new technologies on drinking water resources. One concern is the potential for subsurface drinking water resource contamination by naturally occurring radioactive materials co-extracted during unconventional drilling activities. Given the rate of expansion, opportunities to test drinking water resources in the pre- and post-fracturing setting are rare. This pilot study investigated the levels of natural uranium, lead-210, and polonium-210 in private drinking wells within 2000 m of a large-volume hydraulic fracturing operation--before and approximately one-year following the fracturing activities. Observed radionuclide concentrations in well waters tested did not exceed maximum contaminant levels recommended by state and federal agencies. No statistically-significant differences in radionuclide concentrations were observed in well-water samples collected before and after the hydraulic fracturing activities. Expanded monitoring of private drinking wells before and after hydraulic fracturing activities is needed to develop understanding of the potential for drinking water resource contamination from unconventional drilling and gas extraction activities. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Design configurations affecting flow pattern and solids accumulation in horizontal free water and subsurface flow constructed wetlands.

    Science.gov (United States)

    Pedescoll, A; Sidrach-Cardona, R; Sánchez, J C; Carretero, J; Garfi, M; Bécares, E

    2013-03-01

    The aim of this study was to evaluate the effect of different horizontal constructed wetland (CW) design parameters on solids distribution, loss of hydraulic conductivity over time and hydraulic behaviour, in order to assess clogging processes in wetlands. For this purpose, an experimental plant with eight CWs was built at mesocosm scale. Each CW presented a different design characteristic, and the most common CW configurations were all represented: free water surface flow (FWS) with different effluent pipe locations, FWS with floating macrophytes and subsurface flow (SSF), and the presence of plants and specific species (Typha angustifolia and Phragmites australis) was also considered. The loss of the hydraulic conductivity of gravel was greatly influenced by the presence of plants and organic load (representing a loss of 20% and c.a. 10% in planted wetlands and an overloaded system, respectively). Cattail seems to have a greater effect on the development of clogging since its below-ground biomass weighed twice as much as that of common reed. Hydraulic behaviour was greatly influenced by the presence of a gravel matrix and the outlet pipe position. In strict SSF CW, the water was forced to cross the gravel and tended to flow diagonally from the top inlet to the bottom outlet (where the inlet and outlet pipes were located). However, when FWS was considered, water preferentially flowed above the gravel, thus losing half the effective volume of the system. Only the presence of plants seemed to help the water flow partially within the gravel matrix. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. A Many-Task Parallel Approach for Multiscale Simulations of Subsurface Flow and Reactive Transport

    Energy Technology Data Exchange (ETDEWEB)

    Scheibe, Timothy D.; Yang, Xiaofan; Schuchardt, Karen L.; Agarwal, Khushbu; Chase, Jared M.; Palmer, Bruce J.; Tartakovsky, Alexandre M.

    2014-12-16

    Continuum-scale models have long been used to study subsurface flow, transport, and reactions but lack the ability to resolve processes that are governed by pore-scale mixing. Recently, pore-scale models, which explicitly resolve individual pores and soil grains, have been developed to more accurately model pore-scale phenomena, particularly reaction processes that are controlled by local mixing. However, pore-scale models are prohibitively expensive for modeling application-scale domains. This motivates the use of a hybrid multiscale approach in which continuum- and pore-scale codes are coupled either hierarchically or concurrently within an overall simulation domain (time and space). This approach is naturally suited to an adaptive, loosely-coupled many-task methodology with three potential levels of concurrency. Each individual code (pore- and continuum-scale) can be implemented in parallel; multiple semi-independent instances of the pore-scale code are required at each time step providing a second level of concurrency; and Monte Carlo simulations of the overall system to represent uncertainty in material property distributions provide a third level of concurrency. We have developed a hybrid multiscale model of a mixing-controlled reaction in a porous medium wherein the reaction occurs only over a limited portion of the domain. Loose, minimally-invasive coupling of pre-existing parallel continuum- and pore-scale codes has been accomplished by an adaptive script-based workflow implemented in the Swift workflow system. We describe here the methods used to create the model system, adaptively control multiple coupled instances of pore- and continuum-scale simulations, and maximize the scalability of the overall system. We present results of numerical experiments conducted on NERSC supercomputing systems; our results demonstrate that loose many-task coupling provides a scalable solution for multiscale subsurface simulations with minimal overhead.

  3. Subsurface flow pathway dynamics in the active layer of coupled permafrost-hydrogeological systems under seasonal and annual temperature variability.

    Science.gov (United States)

    Frampton, Andrew

    2017-04-01

    There is a need for improved understanding of the mechanisms controlling subsurface solute transport in the active layer in order to better understand permafrost-hydrological-carbon feedbacks, in particular with regards to how dissolved carbon is transported in coupled surface and subsurface terrestrial arctic water systems under climate change. Studying solute transport in arctic systems is also relevant in the context of anthropogenic pollution which may increase due to increased activity in cold region environments. In this contribution subsurface solute transport subject to ground surface warming causing permafrost thaw and active layer change is studied using a physically based model of coupled cryotic and hydrogeological flow processes combined with a particle tracking method. Changes in subsurface water flows and solute transport travel times are analysed for different modelled geological configurations during a 100-year warming period. Results show that for all simulated cases, the minimum and mean travel times increase non-linearly with warming irrespective of geological configuration and heterogeneity structure. The timing of the start of increase in travel time depends on heterogeneity structure, combined with the rate of permafrost degradation that also depends on material thermal and hydrogeological properties. These travel time changes are shown to depend on combined warming effects of increase in pathway length due to deepening of the active layer, reduced transport velocities due to a shift from horizontal saturated groundwater flow near the surface to vertical water percolation deeper into the subsurface, and pathway length increase and temporary immobilization caused by cryosuction-induced seasonal freeze cycles. The impact these change mechanisms have on solute and dissolved substance transport is further analysed by integrating pathway analysis with a Lagrangian approach, incorporating considerations for both dissolved organic and inorganic

  4. Effects of sorption, sulphate reduction, and Phragmites australis on the removal of heavy metals in subsurface flow constructed wetland microcosms.

    Science.gov (United States)

    Lesage, E; Rousseau, D P L; Van de Moortel, A; Tack, F M G; De Pauw, N; Verloo, M G

    2007-01-01

    The removal of Co, Ni, Cu and Zn from synthetic industrial wastewater was studied in subsurface flow constructed wetland microcosms filled with gravel or a gravel/straw mixture. Half of the microcosms were planted with Phragmites australis and half were left unplanted. All microcosms received low-strength wastewater (1 mg L(-1) of Co, Ni, and Zn, 0.5 mg L(-1) Cu, 2,000mg L(-1) SO4) during seven 14-day incubation batches. The pore water was regularly monitored at two depths for heavy metals, sulphate, organic carbon and redox potential. Sorption properties of gravel and straw were assessed in a separate experiment. A second series of seven incubation batches with high-strength wastewater (10 mg L(-1) of each metal, 2,000 mg L(-1) SO4) was then applied to saturate the substrate. Glucose was added to the gravel microcosms together with the high-strength wastewater. Sorption processes were responsible for metal removal during start-up, with the highest removal efficiencies in the gravel microcosms. The lower initial efficiencies in the gravel/straw microcosms were presumably caused by the decomposition of straw. However, after establishment of anaerobic conditions (Eh approximately -200 mV), precipitation as metal sulphides provided an additional removal pathway in the gravel/straw microcosms. The addition of glucose to gravel microcosms enhanced sulphate reduction and metal removal, although Phragmites australis negatively affected these processes in the top-layer of all microcosms.

  5. Comparison of microfauna communities in full scale subsurface flow constructed wetlands used as secondary and tertiary treatment.

    Science.gov (United States)

    Puigagut, Jaume; Salvadó, Humbert; García, David; Granes, Francesc; García, Joan

    2007-04-01

    In order to evaluate the microfauna composition and distribution in two horizontal subsurface flow constructed wetlands used as secondary and tertiary treatment a full-scale wastewater treatment plant was monitored during five months. Results indicate that total microfauna abundance in the wetland treating primary influents is around five times higher than that found in the wetland treating secondary influents. Ciliated protozoa and microflagellates are the most important microfauna groups in both wetlands; microflagellates in terms of abundance and ciliates in terms of biomass. The most abundant ciliate species in the wetland treating primary influents are polysaprobic organisms as Dexiostoma campylum, Trimyema compressum, and to a lesser extend Metopus spp. On the other hand, the most important ciliate species found in the wetland treating secondary influents are mainly aerobic ciliates as Vorticella comvallaria-complex, Aspidisca cicada, Litonotus lamella and some ciliates belonging to the group of the scuticociliates and Hypotrichidae. The sort of the organic matter treated (particulated or dissolved) is at least as important as the amount of it in order to explain microfauna dynamics in constructed wetlands.

  6. Sub-Surface Meridional flow, Vorticity and the life time if Solar Active Regions

    CERN Document Server

    Maurya, R A

    2010-01-01

    Solar sub-surface fluid topology provides an indirect approach to examine the internal characteristics of active regions (ARs). Earlier studies have revealed the prevalence of strong flows in the interior of ARs having complex magnetic fields. Using the Doppler data obtained by the Global Oscillation Network Group (GONG) project for a sample of 74 ARs, we have discovered the presence of steep gradients in meridional velocity at depths ranging from 1.5 to 5 Mm in flare productive ARs. The sample of these ARs is taken from the Carrington rotations 1980--2052 covering the period August 2001-January 2007. The gradients showed an interesting hemispheric trend of negative (positive) signs in the northern (southern) hemisphere, i.e., directed toward the equator. We have discovered three sheared layers in the depth range of 0 - 10 Mm, providing an evidence of complex flow structures in several ARs. An important inference derived from our analysis is that the location of the deepest zero vertical vorticity is correlat...

  7. Textural evidence for jamming and dewatering of a sub-surface, fluid-saturated granular flow

    Science.gov (United States)

    Sherry, T. J.; Rowe, C. D.; Kirkpatrick, J. D.; Brodsky, E. E.

    2011-12-01

    Sand injectites are spectacular examples of large-scale granular flows involving migration of hundreds of cubic meters of sand slurry over hundreds of meters to kilometers in the sub-surface. By studying the macro- and microstructural textures of a kilometer-scale sand injectite, we interpret the fluid flow regimes during emplacement and define the timing of formation of specific textures in the injected material. Fluidized sand sourced from the Santa Margarita Fm., was injected upward into the Santa Cruz Mudstone, Santa Cruz County, California. The sand injectite exposed at Yellow Bank Beach records emplacement of both hydrocarbon and aqueous sand slurries. Elongate, angular mudstone clasts were ripped from the wall rock during sand migration, providing evidence for high velocity, turbid flow. However, clast long axis orientations are consistently sub-horizontal suggesting the slurry transitioned to a laminar flow as the flow velocity decreased in the sill-like intrusion. Millimeter to centimeter scale laminations are ubiquitous throughout the sand body and are locally parallel to the mudstone clast long axes. The laminations are distinct in exposure because alternating layers are preferentially cemented with limonite sourced from later groundwater infiltration. Quantitative microstructural analyses show that the laminations are defined by subtle oscillations in grain alignment between limonite and non-limonite stained layers. Grain packing, size and shape distributions do not vary. The presence of limonite in alternating layers results from differential infiltration of groundwater, indicating permeability changes between the layers despite minimal grain scale differences. Convolute dewatering structures deform the laminations. Dolomite-cemented sand, a signature of hydrocarbon saturation, forms irregular bodies that cross-cut the laminations and dewatering structures. Laminations are not formed in the dolomite-cemented sand. The relative viscosity difference

  8. Using NMR, SIP, and MS measurements for monitoring subsurface biogeochemical reactions at the Rifle IFRC site

    Science.gov (United States)

    Rosier, C. L.; Keating, K.; Williams, K. H.; Robbins, M.; Ntarlagiannis, D.; Grunewald, E.; Walsh, D. O.

    2013-12-01

    The Rifle Integrated Field Research Challenge (IFRC) site is located on a former uranium ore-processing facility in Rifle, Colorado (USA). Although removal of tailings and contaminated surface materials was completed in 1996, residual uranium contamination of groundwater and subsurface sediments remains. Since 2002, research at the site has primarily focused on quantifying uranium mobility associated with stimulated and natural biogeochemical processes. Uranium mobility at the Rifle IFRC site is typically quantified through direct sampling of groundwater; however, direct sampling does not provide information about the solid phase material outside of the borehole and continuous measurements are not always possible due to multiple constraints. Geophysical methods have been suggested as a minimally invasive alternative approach for long term monitoring of biogeochemical reactions associated with uranium remediation. In this study, nuclear magnetic resonance (NMR), spectral induced polarization (SIP), and magnetic susceptibility (MS) are considered as potential geophysical methods for monitoring the biogeochemical reactions occurring at the Rifle IFRC site. Additionally, a pilot field study using an NMR borehole-logging tool was carried out at the Rifle IFRC site. These methods are sensitive to changes in the chemical and physical subsurface properties that occur as a result of bioremediation efforts; specifically, changes in the redox state and chemical form of iron, production of iron sulfide minerals, production of the magnetic mineral magnetite, and associated changes in the pore geometry. Laboratory experiments consisted of monitoring changes in the NMR, SIP and MS response of an acetate-amended columns packed with sediments from the Rifle IFRC site over the course of two months. The MS values remained relatively stable throughout the course of the experiment suggesting negligible production of magnetic phases (e.g. magnetite, pyrrhotite) as a result of enhanced

  9. Smoothness monitors for compressible flow computation

    Energy Technology Data Exchange (ETDEWEB)

    Sjogreen, B; Yee, H C

    2008-09-02

    In [SY04, YS07] and references cited therein, the authors introduced the concept of employing multiresolution wavelet decomposition of computed flow data as smoothness monitors (flow sensors) to indicate the amount and location of built-in numerical dissipation that can be eliminated or further reduced in shock-capturing schemes. Studies indicated that this approach is able to limit the use of numerical dissipation with improved accuracy compared with standard shock-capturing methods. The studies in [SY04, YS07] were limited to low order multiresolution redundant wavelets with low level supports and low order vanishing moments. The objective of this paper is to expand the previous investigation to include higher order redundant wavelets with larger support and higher order vanishing moments for a wider spectrum of flow type and flow speed applications.

  10. Uncertainties have a Meaning: Quantitative Interpretation of the Relationship between Subsurface Flow and Geological Data Quality

    Science.gov (United States)

    Wellmann, J.; Regenauer-Lieb, K.; Western Australian Geothermal Centre of Excellence

    2011-12-01

    We present a new method to assess system-based measures to classify uncertainties in geological models and in subsurface flow fields. Information entropy is proposed to evaluate uncertainties in geological models, and thermal entropy production is proposed to analyze uncertainties related to hydrothermal flow. As these measures have a fundamental theoretical basis and are related to the internal state of the system, they can be interpreted quantitatively and, consequently, give uncertainties a meaning. Information entropy values are directly related to the state of uncertainty of a geological model. For a point within the model, information entropy is a measure of the minimum number of geological units that could occur at its location. If the information entropy is zero, only one unit is possible and no uncertainty exists. If the value is greater than zero, at least two units are probable. If it increases above 1, three units can occur. In general the measure provides a weight of probabiliy for different states. A strong point of the method is that it gives an entropy measure for the state of the entire model and therefore lends itself as a robust measure to quantitatively compare uncertainties in difference models. In a similar sense, the thermal entropy production provides a quantitative measure of the thermodynamic state of a hydrothermal system. When the entropy production is zero, the system must be in a conductive steady state for a closed system. If the entropy production is larger than zero, the system can be in a convective or transient conductive state. For higher values of entropy production, the convective units show higher complexities and, hence, uncertainty of the hydrothermal field increases. Moreover, the average model entropy production gives a measure of the convective vigour that can be expected in the system. This is directly related to the efficiency of heat transfer over the system. The measure is therefore not only useful for a

  11. Electrical signatures of ethanol-liquid mixtures: implications for monitoring biofuels migration in the subsurface

    Science.gov (United States)

    Personna, Yves Robert; Slater, Lee; Ntarlagiannis, Dimitrios; Werkema, Dale; Szabo, Zoltan

    2013-01-01

    Ethanol (EtOH), an emerging contaminant with potential direct and indirect environmental effects, poses threats to water supplies when spilled in large volumes. A series of experiments was directed at understanding the electrical geophysical signatures arising from groundwater contamination by ethanol. Conductivity measurements were performed at the laboratory scale on EtOH–water mixtures (0 to 0.97 v/v EtOH) and EtOH–salt solution mixtures (0 to 0.99 v/v EtOH) with and without a sand matrix using a conductivity probe and a four-electrode electrical measurement over the low frequency range (1–1000 Hz). A Lichtenecker–Rother (L–R) type mixing model was used to simulate electrical conductivity as a function of EtOH concentration in the mixture. For all three experimental treatments increasing EtOH concentration resulted in a decrease in measured conductivity magnitude (|σ|). The applied L–R model fitted the experimental data at concentration ≤ 0.4 v/v EtOH, presumably due to predominant and symmetric intermolecular (EtOH–water) interaction in the mixture. The deviation of the experimental |σ| data from the model prediction at higher EtOH concentrations may be associated with hydrophobic effects of EtOH–EtOH interactions in the mixture. The |σ| data presumably reflected changes in relative strength of the three types of interactions (water–water, EtOH–water, and EtOH–EtOH) occurring simultaneously in EtOH–water mixtures as the ratio of EtOH to water changed. No evidence of measurable polarization effects at the EtOH–water and EtOH–water–mineral interfaces over the investigated frequency range was found. Our results indicate the potential for using electrical measurements to characterize and monitor EtOH spills in the subsurface.

  12. Computerized flow monitors detect small kicks

    Energy Technology Data Exchange (ETDEWEB)

    McCann, D.; White, D. (Sedco Forex, Paris (FR))

    1992-02-24

    This paper reports on a smart alarm system installed on a number of offshore rigs and one land rig which can detect kicks more quickly than conventional systems. This rapid kick detection improves rig safety because the smaller the detected influx, the easier it is to control the well. The extensive computerized monitoring system helps drilling personnel detect fluid influxes and fluid losses before the changes in flow would normally be apparent.

  13. [Segregation effect of purification for nitrogen and phosphate pollution in the subsurface flow constructed wetlands].

    Science.gov (United States)

    Liu, Shu-Yuan; Yan, Bai-Xing; Wang, Li-Xia

    2011-03-01

    Three minitype subsurface-horizontal flow constructed wetlands planted with Calamagrostis angustifolia and Phragmites australis and filled with soil and slag were used to investigate the N, P and pH for upper layer and underlayer wetland system by intermission operation. Results demonstrated that TN removal rates in the superstratum of Calamagrostis angustifolia and Phragmites australis wetlands were 0.771 g x (m2 x d)(-1), 1.481 g x(m2 x d)(-1) with 10 days of the hydraulic retention, which were 1.15 and 1.31 times higher than that of underlayer wetland systems, respectively. Simultaneity, TP removal rates in the superstratum of Calamagrostis angustifolia and Phragmites australis wetlands were 1.655 g x (m2 x d)(-1), 6.838 g x (m2 x d)(-1), respectively, which were 1.13 and 1.28 times higher than that of underlayer wetland systems, respectively. The purification ability of upper layer in the wetland system was higher than that of underlayer. A regular trend of pH changes and upstanding buffer ability of wetland system were found. The pH values in the upper layer of soil-slag wetlands were smaller than that of underlayer which was contrary to the soil wetland. The break-point of pH curve indicates the termination of NH4(+) -N reaction in constructed wetland.

  14. Hybrid nested sampling algorithm for Bayesian model selection applied to inverse subsurface flow problems

    KAUST Repository

    Elsheikh, Ahmed H.

    2014-02-01

    A Hybrid Nested Sampling (HNS) algorithm is proposed for efficient Bayesian model calibration and prior model selection. The proposed algorithm combines, Nested Sampling (NS) algorithm, Hybrid Monte Carlo (HMC) sampling and gradient estimation using Stochastic Ensemble Method (SEM). NS is an efficient sampling algorithm that can be used for Bayesian calibration and estimating the Bayesian evidence for prior model selection. Nested sampling has the advantage of computational feasibility. Within the nested sampling algorithm, a constrained sampling step is performed. For this step, we utilize HMC to reduce the correlation between successive sampled states. HMC relies on the gradient of the logarithm of the posterior distribution, which we estimate using a stochastic ensemble method based on an ensemble of directional derivatives. SEM only requires forward model runs and the simulator is then used as a black box and no adjoint code is needed. The developed HNS algorithm is successfully applied for Bayesian calibration and prior model selection of several nonlinear subsurface flow problems. © 2013 Elsevier Inc.

  15. Efficient Bayesian inference of subsurface flow models using nested sampling and sparse polynomial chaos surrogates

    KAUST Repository

    Elsheikh, Ahmed H.

    2014-02-01

    An efficient Bayesian calibration method based on the nested sampling (NS) algorithm and non-intrusive polynomial chaos method is presented. Nested sampling is a Bayesian sampling algorithm that builds a discrete representation of the posterior distributions by iteratively re-focusing a set of samples to high likelihood regions. NS allows representing the posterior probability density function (PDF) with a smaller number of samples and reduces the curse of dimensionality effects. The main difficulty of the NS algorithm is in the constrained sampling step which is commonly performed using a random walk Markov Chain Monte-Carlo (MCMC) algorithm. In this work, we perform a two-stage sampling using a polynomial chaos response surface to filter out rejected samples in the Markov Chain Monte-Carlo method. The combined use of nested sampling and the two-stage MCMC based on approximate response surfaces provides significant computational gains in terms of the number of simulation runs. The proposed algorithm is applied for calibration and model selection of subsurface flow models. © 2013.

  16. Boosting iterative stochastic ensemble method for nonlinear calibration of subsurface flow models

    KAUST Repository

    Elsheikh, Ahmed H.

    2013-06-01

    A novel parameter estimation algorithm is proposed. The inverse problem is formulated as a sequential data integration problem in which Gaussian process regression (GPR) is used to integrate the prior knowledge (static data). The search space is further parameterized using Karhunen-Loève expansion to build a set of basis functions that spans the search space. Optimal weights of the reduced basis functions are estimated by an iterative stochastic ensemble method (ISEM). ISEM employs directional derivatives within a Gauss-Newton iteration for efficient gradient estimation. The resulting update equation relies on the inverse of the output covariance matrix which is rank deficient.In the proposed algorithm we use an iterative regularization based on the ℓ2 Boosting algorithm. ℓ2 Boosting iteratively fits the residual and the amount of regularization is controlled by the number of iterations. A termination criteria based on Akaike information criterion (AIC) is utilized. This regularization method is very attractive in terms of performance and simplicity of implementation. The proposed algorithm combining ISEM and ℓ2 Boosting is evaluated on several nonlinear subsurface flow parameter estimation problems. The efficiency of the proposed algorithm is demonstrated by the small size of utilized ensembles and in terms of error convergence rates. © 2013 Elsevier B.V.

  17. [Effect of Intermittent Aeration on Nitrogen Removal Efficiency in Vertical Subsurface Flow Constructed Wetland].

    Science.gov (United States)

    Wang, Jian; Li, Huai-zheng; Zhen, Bao-chong; Liu, Zhen-dong

    2016-03-15

    One-stage vertical subsurface flow constructed wetlands (CWs) were used to treat effluent from grit chamber in municipal wastewater treatment plant. The CW was divided into aerobic zone and anoxic zone by means of raising the effluent level and installing a perforated pipe. Two parameters (the ratio of aeration time and nonaeration time, aeration cycle) were optimized in the experiment to enhance nitrogen removal efficiency. The results suggested that the removal rates of COD and NH₄⁺-N increased while TN showed a trend of first increasing and then decreasing with the increasing ratio. When the ratio was 3:1, the C/N value in the anoxic zone was 4. 8. And the TN effluent concentration was 15.8 mg · L⁻¹ with the highest removal rate (62.1%), which was increased by 12.7% compared with continuous aeration. As the extension of the aeration cycle, the DO effluent concentration as well as the removal rates of COD and NH: -N declined gradually. The TN removal rate reached the maximum (65.5%) when the aeration cycle was 6h. However, the TN removal rate dropped rapidly when the cycle exceeded the hydraulic retention time in the anoxic zone.

  18. Purification of landscape water by using an innovative application of subsurface flow constructed wetland.

    Science.gov (United States)

    Chyan, Jih Ming; Lu, Chien Chang; Shiu, Ruei Feng; Bellotindos, Luzvisminda M

    2016-01-01

    This study attempted to purify eutrophic landscape water under a low pollutant concentration and high hydraulic volume loading using an embedded subsurface flow (SSF) constructed wetland (CW). Three species of aquatic plants (i.e., Cyperus alternifolius subsp. flabelliformis, Canna indica, and Hydrocotyle verticillata) were found to be conducive to the requirements of purifying the low-polluted water. Field results of nearly 2 years of experiments showed that SSF CW purified the eutrophic water and maintained the landscape water in a visibly clear condition. In an environment approaching the SSF CW background concentration, pollutant removal processes were divided into modulation and optimum performance periods. Average concentrations of biochemical oxygen demand (BOD), ammonium-nitrogen (NH4 (+)-N), and total phosphorous (TP) in the optimum performance period were 0.69-1.00, 0.35-1.42, and 0.19-0.23 mg/L, respectively. Almost 500 days of BOD and NH4 (+)-N removals were necessary to perform optimally. A shorter period, 350 days, was required for TP optimum removal. This feature of two stage removals was not found in chlorophyll-a (Chl-a) and suspended solids (SS), whose averages were 11.86-17.98 and 13.30 μg/L, respectively. Filter cleaning and water replacement were unnecessary, while only water recharging was needed to compensate for the water lost by evapotranspiration. The field SSF CW has maintained its performance level for over 7 years.

  19. A Hardy Plant Facilitates Nitrogen Removal via Microbial Communities in Subsurface Flow Constructed Wetlands in Winter

    Science.gov (United States)

    Wang, Penghe; Zhang, Hui; Zuo, Jie; Zhao, Dehua; Zou, Xiangxu; Zhu, Zhengjie; Jeelani, Nasreen; Leng, Xin; An, Shuqing

    2016-09-01

    The plants effect in subsurface flow constructed wetlands (SSF-CWs) is controversial, especially at low temperatures. Consequently, several SSF-CWs planted with Iris pseudacorus (CWI) or Typha orientalis Presl. (CWT) and several unplanted ones (CWC) were set up and fed with secondary effluent of sewage treatment plant during the winter in Eastern China. The 16S rDNA Illumina Miseq sequencing analysis indicated the positive effects of I. pseudacorus on the bacterial community richness and diversity in the substrate. Moreover, the community compositions of the bacteria involved with denitrification presented a significant difference in the three systems. Additionally, higher relative abundances of nitrifying bacteria (0.4140%, 0.2402% and 0.4318% for Nitrosomonas, Nitrosospira and Nitrospira, respectively) were recorded in CWI compared with CWT (0.2074%, 0.0648% and 0.0181%, respectively) and CWC (0.3013%, 0.1107% and 0.1185%, respectively). Meanwhile, the average removal rates of NH4+-N and TN in CWI showed a prominent advantage compared to CWC, but no distinct advantage was found in CWT. The hardy plant I. pseudacorus, which still had active root oxygen release in cold temperatures, positively affected the abundance of nitrifying bacteria in the substrate, and accordingly was supposed to contribute to a comparatively high nitrogen removal efficiency of the system during the winter.

  20. Phytoremediation of selenium by two helophyte species in subsurface flow constructed wetland.

    Science.gov (United States)

    Shardendu; Salhani, N; Boulyga, S F; Stengel, E

    2003-03-01

    The phytoremediation of selenium by two different wetland species was investigated. Selenium (20.4 microg/l) was supplied continuously to subsurface flow constructed wetlands, one vegetated with Typha latifolia L. and the other with Phragmites australis (Cav.) Trin. ex Steud. The beds of both species had same hydraulic loading rate (0.079 m(3)/m(2)/d) and water retention time (24 h). However, the mass loading rate was 1.27 mg Se/m(2)/d for Phragmites and 1.35 mg Se/m(2)/d for Typha. In the Typha bed Se migrated faster than in the Phragmites bed. After 25 d of Se supplementation in the Typha bed about 54% of the Se inlet concentration remained in the outlet water. In the Phragmites bed Se was removed completely from the water after passing through 3/4 of the bed length. After 65 d of Se supplementation the highest amount of Se (2.8 microg/g dry matter) was determined in the organic material of the Typha bed. Roots and rhizomes accumulated 2.2 and 1.8 microg/g dry matter respectively. Phragmites accumulated Se in the leaves and stems, but not in the rhizomes. The accumulation in the leaves (1.8 microg Se/g dry matter) was three times higher than in the stems (0.6 microg Se/g dry matter). Copyright 2002 Elsevier Science Ltd.

  1. Application of computational fluid dynamic to model the hydraulic performance of subsurface flow wetlands

    Institute of Scientific and Technical Information of China (English)

    FAN Liwei; Hai Reti; WANG Wenxing; LU Zexiang; YANG Zhiming

    2008-01-01

    A subsurface flow wetland (SSFW) was simulated using a commercial computational fluid dynamic (CFD) code. The constructed media was simulated using porous media and the liquid resident time distribution (RTD) in the SSFW was obtained using the particle trajectory model. The effect of wetland configuration and operating conditions on the hydraulic performance of the SSFW were investigated. The results indicated that the hydraulic performance of the SSFW was predominantly affected by the wetland configuration. The hydraulic efficiency of the SSFW with an inlet at the middle edge of the upper media was 0.584 and the best among the SSFWs with an inlet at the top, the middle, and the bottom edge of the upper media. The constructed media affected the hydraulic performance by the ratio (K) of the upper and lower media resistance. The selection of appropriate media resistance in the protection layer can improve the hydraulic efficiency. When the viscous resistance coefficient of the media in the protection layer changed from 2.315×105 to 1.200×108, the hydraulic efficiency of the SSFW increased from 0.301 to 0.751. However, the effect of operating conditions on the hydraulic efficiency of the SSFW was slight.

  2. A Hardy Plant Facilitates Nitrogen Removal via Microbial Communities in Subsurface Flow Constructed Wetlands in Winter

    Science.gov (United States)

    Wang, Penghe; Zhang, Hui; Zuo, Jie; Zhao, Dehua; Zou, Xiangxu; Zhu, Zhengjie; Jeelani, Nasreen; Leng, Xin; An, Shuqing

    2016-01-01

    The plants effect in subsurface flow constructed wetlands (SSF-CWs) is controversial, especially at low temperatures. Consequently, several SSF-CWs planted with Iris pseudacorus (CWI) or Typha orientalis Presl. (CWT) and several unplanted ones (CWC) were set up and fed with secondary effluent of sewage treatment plant during the winter in Eastern China. The 16S rDNA Illumina Miseq sequencing analysis indicated the positive effects of I. pseudacorus on the bacterial community richness and diversity in the substrate. Moreover, the community compositions of the bacteria involved with denitrification presented a significant difference in the three systems. Additionally, higher relative abundances of nitrifying bacteria (0.4140%, 0.2402% and 0.4318% for Nitrosomonas, Nitrosospira and Nitrospira, respectively) were recorded in CWI compared with CWT (0.2074%, 0.0648% and 0.0181%, respectively) and CWC (0.3013%, 0.1107% and 0.1185%, respectively). Meanwhile, the average removal rates of NH4+-N and TN in CWI showed a prominent advantage compared to CWC, but no distinct advantage was found in CWT. The hardy plant I. pseudacorus, which still had active root oxygen release in cold temperatures, positively affected the abundance of nitrifying bacteria in the substrate, and accordingly was supposed to contribute to a comparatively high nitrogen removal efficiency of the system during the winter. PMID:27646687

  3. Use of horizontal subsurface flow constructed wetlands to treat reverse osmosis concentrate of rolling wastewater.

    Science.gov (United States)

    Xu, Jingcheng; Zhao, Gang; Huang, Xiangfeng; Guo, Haobo; Liu, Wei

    2017-03-04

    According to the characteristics of the reverse osmosis concentrate (ROC) generated from iron and steel company, we used three sets of parallel horizontal subsurface flow (HSF) constructed wetlands (CWs) with different plants and substrate layouts to treat the high-salinity wastewater. The plant growth and removal efficiencies under saline condition were evaluated. The evaluation was based entirely on routinely collected water quality data and the physical and chemical characteristics of the plants (Phragmites australis, Typha latifolia, Iris wilsonii, and Scirpus planiculmis). The principal parameters of concern in the effluent were chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP). The results showed that the CWs were able to remove COD, TN, and TP from ROC. S. planiculmis was not suitable for the treatment of high-saline wastewater. The sequence of metals accumulated in CW plants was K>Ca>Na>Mg>Zn>Cu. More than 70% of metals were accumulated in the aboveground of P. australis. The CW filled with gravel and manganese ore and planted with P. australis and T. latifolia had the best performance of pollutant removal, with average removal of 49.96%, 39.45%, and 72.01% for COD, TN, and TP, respectively. The effluent water quality met the regulation in China. These results suggested that HSF CW planted with P. australis and T. latifolia can be applied for ROC pollutants removal.

  4. Experiment Research on Purifying Domestic Sewage by Duplex Subsurface Flow Constructed Wetlands

    Directory of Open Access Journals (Sweden)

    SHANG Ping

    2014-04-01

    Full Text Available The purification effect on domestic sewage were researched in the new-type of duplex subsurface flow constructed wetlands, of which pollutants were analyzed through the small scale test on the purification effect under different conditions of hydraulic loading, season,aeration pattern. The results showed that water quality of the system was stabilized, which could reach the 1 class A criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant ( GB 18918-2002.The removal rate of COD,NH3-N could reach up to 87.2%, 68.9% under the conditions of the hydraulic load being 184 mm·d-1.And there were still more than 20% removal efficien-cy of various pollutants on the conditions of low temperature in winter. Orthogonal test showed that the optimum operating conditions was 28.6℃for the temperature, 0.184 m3·m-2·d-1 for hydraulic loading, and 2.4 d for hydraulic retention time. The experimental research showed that pre-aeration was significantly better than the anaerobic treatment on purifying effect.

  5. Nitrogen and COD removal from domestic and synthetic wastewater in subsurface-flow constructed wetlands.

    Science.gov (United States)

    Collison, R S; Grismer, M E

    2013-09-01

    Comparisons of the performance of constructed-wetland systems (CWs) for treating domestic wastewater in the laboratory and field may use pathogen-free synthetic wastewater to avoid regulatory health concerns. However, little to no data are available describing the relative treatment efficiencies of CWs to both actual and synthetic domestic wastewaters so as to enable such comparison. To fill this gap, treatment performances with respect to organics (chemical organic demand; COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) and a similar-strength synthetic wastewater under planted and non-planted subsurface-flow CWs are determined. One pair of CWs was planted with cattails in May 2008, whereas the adjacent system was non-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each CWs, and effluent samples were collected and tested for COD and nitrogen species regularly during four different periods over six months. Overall, statistically significant greater removal of COD (-12%) and nitrogen (-5%) occurred from the synthetic as compared with the domestic wastewater from the planted and non-planted CWs. Effluent BOD5/COD ratios from the synthetic wastewater CWs averaged nearly twice that from the domestic wastewater CWs (0.17 vs 0.10), reflecting greater concentrations of readily degraded compounds. That removal fractions were consistent across the mid-range loading rates to the CWs suggests that the synthetic wastewater can be used in testing laboratory CWs with reasonable success in application of their results to the field.

  6. Wastewater treatment in horizontal subsurface flow constructed wetlands using different media (setup stage

    Directory of Open Access Journals (Sweden)

    Abdel Razik A. Zidan

    2015-04-01

    Full Text Available Wastewater treatment through horizontal subsurface flow (HSSF constructed wetlands (CWs using three different treatment media (gravel, pieces of plastic pipes, and shredded tire rubber chips were investigated in Samaha village, Dakahliya, Egypt. The study focused on the wetland setup stage during the first months of its operation (setup stage. In this stage media porosity, bacterial biofilm, and plant roots growth were in progress and it was prior to the operational steady state stage. Objectives of this paper are to study the change in media porosity of HSSF wetland cells in order to estimate duration of wetland setup stage, and to evaluate the use of different bed media on biological oxygen demand (BOD, chemical oxygen demand (COD and total suspended solids (TSS treatment. The results showed that after 180 days of operation, the wetland cells had reached steady porosity and had started stable treatment. Also performance of plastic media bed in pollutants reduction was better than gravel and rubber beds and gravel media was in advanced than rubber media.

  7. Removal of total suspended solids from wastewater in constructed horizontal flow subsurface wetlands.

    Science.gov (United States)

    Manios, T; Stentiford, E I; Millner, P

    2003-06-01

    Subsurface horizontal flow experimental wetlands (reed beds), were designed and built based on a combination of two design methodologies, that of the WRc and Severn Trent Water plc (1996) and that of the USA, EPA (1988). Four different growing media were used with a combination of top soil, gravel, river sand, and mature sewage sludge compost, to determine the best substrate for total suspended solids (TSS) removal. Eight units were constructed, two for each growing media. One bed for each pair was planted with Typha latifolia plants commonly known as cattails. Primary treated domestic wastewater, was continuously fed to the beds for more than six months. All eight beds performed very well. The best performance was achieved by the gravel reed beds with an almost constant removal rate above 95% and an average effluent concentration of less than 10 mg/L. Soil based beds containing top soil and sand, managed to reach values of removal around 90%. The wetlands containing compost in their substrate, produced an effluent with average concentration of less than 30 mg/L and a percentage removal between 80% and 90%. As expected, there was no significant difference in the performance of planted and unplanted wetlands.

  8. Geophysical characterization of subsurface barriers

    Energy Technology Data Exchange (ETDEWEB)

    Borns, D.J.

    1995-08-01

    An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier.

  9. Modelling catchment-scale shallow landslide occurrence by means of a subsurface flow path connectivity index

    Directory of Open Access Journals (Sweden)

    C. Lanni

    2012-03-01

    Full Text Available Topographic index-based hydrological models have gained wide use to describe the hydrological control on the triggering of rainfall-induced shallow landslides at the catchment scale. A common assumption in these models is that a spatially continuous water table occurs simultaneously at any point across the catchment. However, during a rainfall event isolated patches of subsurface saturation form above an impeding layer and hydrological connectivity of these patches is a necessary condition for lateral flow initiation at a point on the hillslope.

    Here, a new hydrological model is presented, which allows to account for the concept of hydrological connectivity while keeping the simplicity of the topographic index approach. A dynamic topographic index is used to describe the transient lateral flow that is established at a hillslope element when the rainfall amount exceeds a threshold value allowing for (a development of a perched water table above an impeding layer, (b hydrological connectivity between the hillslope element and its own upslope contributing area. A spatially variable soil depth is the main control of hydrological connectivity in the model. The hydrological model is coupled with the infinite slope stability model, and with a scaling model for the rainfall frequency-duration relationship to determine the return period of the critical rainfall needed to cause instability on three catchments located in the Italian Alps. The results show the good ability of our model in predicting observed shallow landslides. The model is finally used to determine local rainfall intensity-duration thresholds that may lead to shallow landslide initiation.

  10. Developing Training Image-Based Priors for Inversion of Subsurface Geophysical and Flow Data

    Science.gov (United States)

    Caers, J.

    2014-12-01

    Forecasting in subsurface formations, whether for groundwater, storage or oil & gas production, can rely on a wealth of geological information. Currently, most of this information remains underused in both the theory and practice of forecasting based on inverse models which heavily relies on spatial covariances and multi-Gaussian theory. By means of real field studies, I will provide an outline of how such geological information can be accounted through the construction and validation of a large set of training images and the generation of model realizations with MPS (multiple-point geostatistics). Often most critical in solving such inverse problems is the development of prior models that are later used for posterior sampling or stochastic search. I propose therefore a two-stage approach where the first stage consists of a validation of the training image-based prior with the geophysical and flow data. This stage will require only the generation of a few (100s) geological models and the forward modeling of the data response on these models. For geophysical data, the validation consists of comparing histograms of multi-scale wavelet transforms between the forward models and the field data. For flow data, the validation is based on a reduction of dimensionality of the forward response and the data using multi-dimensional scaling. The outcome of this validation is an estimate of the prior probability assigned to each training image, with several training images getting assigned zero probability (incompatible with field data). These prior probabilities are used in the second stage to actually invert for the data using stochastic search. In such stochastic search, I avoid parameterizing the model space and present methods that efficiently perform a direct search in the space of the validated training image-based prior model realizations.

  11. Heat flow and subsurface temperature distributions in central and western New York. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, D.S.; Fromm, K.

    1984-01-01

    Initiation of a geothermal energy program in western and central New York requires knowledge of subsurface temperatures for targeting areas of potential resources. The temperature distribution in possible geothermal reservoirs, calculated from heat flow measurements and modeling techniques, shows that a large area of New York can be considered for exploitation of geothermal resources. Though the temperatures at currently accessible depths show the availability of only a low-temperature (less than 100/sup 0/C), direct-use resource, this can be considered as an alternative for the future energy needs of New York State. From analysis of bottom-hole-temperature data and direct heat flow measurements, estimates of temperatures in the Cambrian Sandstones provide the basis of the economic evaluation of the reservoir. This reservoir contains the extractable fluids needed for targeting a potential geothermal well site in the low-temperature geothermal target zone. In the northern section of the Appalachian basin, reservoir temperatures in the Cambrian are below 50/sup 0/C but may be over 80/sup 0/C in the deeper parts of the basin in southern New York State. Using a minimum of 50/sup 0/C as a useful reservoir temperature, temperatures in excess of this value are encountered in the Theresa Formation at depths in excess of 1300 meters. Considering a maximum depth for economical drilling to be 2500 meters with present technology, the 2500 meters to the Theresa (sea level datum) forms the lower limit of the geothermal resource. Temperatures in the range of 70/sup 0/C to 80/sup 0/C are predicted for the southern portion of New York State.

  12. Relationships between loading rates and nitrogen removal effectiveness in subsurface flow constructed wetlands

    Institute of Scientific and Technical Information of China (English)

    Rongshe ZHANG; Guanghe LI; Qi ZHOU; Xu ZHANG

    2008-01-01

    Nitrogen removal of wetlands under 40 different inflow loadings were studied in the field during 15 months. The removal efficiency of four different sets of beds, namely the reed bed, the Zizania caduciflor bed, the mixing planting bed, and the control bed were studied. The outflow loading and total nitrogen (TN) removal rate of these beds under different inflow loadings and pollution loadings were investigated. The inflow loadings of 4 sub-surface flow systems (SFS) ranged from 400 to 8000 mg· (m2·d)-1, while outflow loadings were less than 7000 mg· (m2·d)-1. The results showed that the inflow and outflow loading of TN removal rate in SFS presented an obvious linear relationship. The optical inflow loading to run the system was between 2000 to 4000 mg·(m2·d)-1. Average removal rate was between 1062 and 2007 mg·(m2·d)-1. SFS with plant had a better removal rate than the control. TN removal rates of the reed and Zizania caduciflora bed were 63% and 27% higher than the control bed, respectively. The results regarding the TN absorption of plants indicated that the absorption amount was very limited, less than 5% of the total removal. It proved that plants clearly increase TN removal rates by improving the water flow, and increasing the biomass, as well as activities of microorganisms around the roots. The research provided a perspective for understanding the TN removal mechanism and design for SFS.

  13. Optimal conditions for chlorothalonil and dissolved organic carbon in horizontal subsurface flow constructed wetlands.

    Science.gov (United States)

    Rìos-Montes, Karina A; Casas-Zapata, Juan C; Briones-Gallardo, Roberto; Peñuela, Gustavo

    2017-04-03

    The most efficient system of horizontal subsurface flow constructed wetlands (HSSFCW) for removing dissolved organic carbon (DOC) in the presence of chlorothalonil pesticide (CLT) present in synthetic domestic wastewater was determined using the macrophyte Phragmites australis. Two concentrations of CLT (85 and 385 μg L(-1)) and one concentration of glucose (20 mg L(-1)) were evaluated in four pilot scale horizontal surface flow constructed wetlands coupled with two sizes of silica gravel, igneous gravel, fine chalky gravel (3.18-6.35 mm), coarse gravel (12.70-25.40 mm) and two water surface heights (20 and 40 cm). For a month, wetlands were acclimated with domestic wastewater. Some groups of bacteria were also identified in the biofilm attached to the gravel. In each treatment periodic samplings were conducted in the influent and effluent. Chlorothalonil was quantified by gas chromatography (GC-ECD m), DOC by an organic carbon analyzer and bacterial groups using conventional microbiology in accordance with Standard Methods. The largest removals of DOC (85.82%-85.31%) were found when using fine gravel (3.18-6.35 mm) and the lower layer of water (20 cm). The bacterial groups quantified in the biofilm were total heterotrophic, revivable heterotrophic, Pseudomonas and total coliforms. The results of this study indicate that fine grain gravel (3.18-6.35 mm) and both water levels (20 to 40 cm) can be used in the removal of organic matter and for the treatment of agricultural effluents contaminated with organo-chloride pesticides like CLT in HSSFCW.

  14. Big Data Architectures for Operationalized Seismic and Subsurface Monitoring and Decision Support Workflows

    Science.gov (United States)

    Irving, D. H.; Rasheed, M.; Hillman, C.; O'Doherty, N.

    2012-12-01

    Oilfield management is moving to a more operational footing with near-realtime seismic and sensor monitoring governing drilling, fluid injection and hydrocarbon extraction workflows within safety, productivity and profitability constraints. To date, the geoscientific analytical architectures employed are configured for large volumes of data, computational power or analytical latency and compromises in system design must be made to achieve all three aspects. These challenges are encapsulated by the phrase 'Big Data' which has been employed for over a decade in the IT industry to describe the challenges presented by data sets that are too large, volatile and diverse for existing computational architectures and paradigms. We present a data-centric architecture developed to support a geoscientific and geotechnical workflow whereby: ●scientific insight is continuously applied to fresh data ●insights and derived information are incorporated into engineering and operational decisions ●data governance and provenance are routine within a broader data management framework Strategic decision support systems in large infrastructure projects such as oilfields are typically relational data environments; data modelling is pervasive across analytical functions. However, subsurface data and models are typically non-relational (i.e. file-based) in the form of large volumes of seismic imaging data or rapid streams of sensor feeds and are analysed and interpreted using niche applications. The key architectural challenge is to move data and insight from a non-relational to a relational, or structured, data environment for faster and more integrated analytics. We describe how a blend of MapReduce and relational database technologies can be applied in geoscientific decision support, and the strengths and weaknesses of each in such an analytical ecosystem. In addition we discuss hybrid technologies that use aspects of both and translational technologies for moving data and analytics

  15. A soil flowing characteristics monitoring method in planetary drilling and coring verification experiments

    Science.gov (United States)

    Tang, Junyue; Quan, Qiquan; Jiang, Shengyuan; Chen, Chongbin; Yuan, Fengpei; Deng, Zongquan

    2017-03-01

    Some type of piercing into the subsurface formation is required in future planetary explorations to enhance the understanding of early stars' geological evolution and the origin of life. Compared with other technical methods, drilling & coring, only utilizing the compound locomotion of rotation and penetration, can sample the subsurface soil relatively efficient and convenient. However, given the uncertain mechanical properties of planetary soil, drilling state signals should be monitored online to improve the robustness of drilling system and avoid potential drilling faults. Since the flowing characteristics of interacted soil, such as removal volume, coring height, removal velocity and accumulation angle, directly reveal the drilling conditions, they are enhancing resources to comprehend the sampling phenomenon and can be used to help control the drill tool. This paper proposed a novel soil flowing characteristics (SFC) monitoring method by applying an industrial camera to record the flowing characteristics of removed cuttings and by utilizing an ultrasonic sensor into the hollow auger to monitor the sampled core. Experiments in one typical lunar regolith simulant indicate that the monitored SFC accurately reflects the interaction between the drill tool and soil.

  16. Climate change and groundwater ecohydrology: Simulating subsurface flow and discharge zones in Covey Hill, Quebec, Canada

    Science.gov (United States)

    Levison, J.; Larocque, M.; Ouellet, M.; van Waterschoot, L.

    2013-12-01

    Nearly 2 billion people use groundwater and in Canada it is the potable water supply for about 30% of the population. Groundwater is also used in industrial and agricultural applications, and contributes to important hydrological habitats for various species. Limited research has been conducted to determine the potential impacts of climate change on groundwater. Local studies are crucial to better understand how, for example, increased duration and frequency of storms or drought periods may affect groundwater dependent ecosystems in order to anticipate and mitigate the impacts. Thus, the aim of this research is to explore the effects of climate change on a groundwater-surface water interacting system that supports a fragile ecosystem. This research is used to inform ecological conservation measures. The research site is the 17500 ha Covey Hill Natural Laboratory, which is located on the Quebec, Canada and New York State, USA border in the Chateauguay River watershed. At various locations within the Natural Laboratory there is continuous monitoring of groundwater levels and river flows. Covey Hill is an important recharge zone for the regional aquifer and provides habitat for endangered salamanders in discharge zones. Two hydrogeological models were constructed to represent flow at the site. First, a three-dimensional, finite difference model was developed using MODFLOW software to simulate overall groundwater flow at the research site. Second, a smaller-scale, discrete fracture, transient, three-dimensional, finite difference, integrated model was developed using HydroGeoSphere software to represent in better detail flow from bedrock springs that occur at mid-slope and provide the habitat for endangered salamanders. The models were used to: 1) observe groundwater flow under current climate conditions; 2) quantify water dynamics in response to climate change using 10 scenarios from the Canadian Regional Climate Model (for 1971-2000 and 2041-2070 time periods); and 3

  17. Improved design and optimization of subsurface flow constructed wetlands and sand filters

    Science.gov (United States)

    Brovelli, A.; Carranza-Díaz, O.; Rossi, L.; Barry, D. A.

    2010-05-01

    Subsurface flow constructed wetlands and sand filters are engineered systems capable of eliminating a wide range of pollutants from wastewater. These devices are easy to operate, flexible and have low maintenance costs. For these reasons, they are particularly suitable for small settlements and isolated farms and their use has substantially increased in the last 15 years. Furthermore, they are also becoming used as a tertiary - polishing - step in traditional treatment plants. Recent work observed that research is however still necessary to understand better the biogeochemical processes occurring in the porous substrate, their mutual interactions and feedbacks, and ultimately to identify the optimal conditions to degrade or remove from the wastewater both traditional and anthropogenic recalcitrant pollutants, such as hydrocarbons, pharmaceuticals, personal care products. Optimal pollutant elimination is achieved if the contact time between microbial biomass and the contaminated water is sufficiently long. The contact time depends on the hydraulic residence time distribution (HRTD) and is controlled by the hydrodynamic properties of the system. Previous reports noted that poor hydrodynamic behaviour is frequent, with water flowing mainly through preferential paths resulting in a broad HRTD. In such systems the flow rate must be decreased to allow a sufficient proportion of the wastewater to experience the minimum residence time. The pollutant removal efficiency can therefore be significantly reduced, potentially leading to the failure of the system. The aim of this work was to analyse the effect of the heterogeneous distribution of the hydraulic properties of the porous substrate on the HRTD and treatment efficiency, and to develop an improved design methodology to reduce the risk of system failure and to optimize existing systems showing poor hydrodynamics. Numerical modelling was used to evaluate the effect of substrate heterogeneity on the breakthrough curves of

  18. Differential Muon Tomography to Continuously Monitor Changes in the Composition of Subsurface Fluids

    Science.gov (United States)

    Coleman, Max; Kudryavtsev, Vitaly A.; Spooner, Neil J.; Fung, Cora; Gluyas, John

    2013-01-01

    Muon tomography has been used to seek hidden chambers in Egyptian pyramids and image subsurface features in volcanoes. It seemed likely that it could be used to image injected, supercritical carbon dioxide as it is emplaced in porous geological structures being used for carbon sequestration, and also to check on subsequent leakage. It should work equally well in any other application where there are two fluids of different densities, such as water and oil, or carbon dioxide and heavy oil in oil reservoirs. Continuous monitoring of movement of oil and/or flood fluid during enhanced oil recovery activities for managing injection is important for economic reasons. Checking on leakage for geological carbon storage is essential both for safety and for economic purposes. Current technology (for example, repeat 3D seismic surveys) is expensive and episodic. Muons are generated by high- energy cosmic rays resulting from supernova explosions, and interact with gas molecules in the atmosphere. This innovation has produced a theoretical model of muon attenuation in the thickness of rock above and within a typical sandstone reservoir at a depth of between 1.00 and 1.25 km. Because this first simulation was focused on carbon sequestration, the innovators chose depths sufficient for the pressure there to ensure that the carbon dioxide would be supercritical. This innovation demonstrates for the first time the feasibility of using the natural cosmic-ray muon flux to generate continuous tomographic images of carbon dioxide in a storage site. The muon flux is attenuated to an extent dependent on, amongst other things, the density of the materials through which it passes. The density of supercritical carbon dioxide is only three quarters that of the brine in the reservoir that it displaces. The first realistic simulations indicate that changes as small as 0.4% in the storage site bulk density could be detected (equivalent to 7% of the porosity, in this specific case). The initial

  19. Evaluation of Subsurface Flow and Free-water Surface Wetlands Treating NPR-3 Produced Water - Year No. 1

    Energy Technology Data Exchange (ETDEWEB)

    Myers, J. E.; Jackson, L. M.

    2001-10-13

    This paper is a summary of some of the activities conducted during the first year of a three-year cooperative research and development agreement (CRADA) between the Department of Energy (DOE) Rocky Mountain Oilfield Testing Center (RMOTC) and Texaco relating to the treatment of produced water by constructed wetlands. The first year of the CRADA is for design, construction and acclimation of the wetland pilot units. The second and third years of the CRADA are for tracking performance of pilot wetlands as the plant and microbial communities mature. A treatment wetland is a proven technology for the secondary and tertiary treatment of produced water, storm water and other wastewaters. Treatment wetlands are typically classified as either free-water surface (FWS) or subsurface flow (SSF). Both FWS and SSF wetlands work well when properly designed and operated. This paper presents a collection of kinetic data gathered from pilot units fed a slipstream of Wyoming (NPR-3) produced water. The pilot units are set up outdoors to test climatic influences on treatment. Monitoring parameters include evapotranspiration, plant growth, temperature, and NPDES discharge limits. The pilot wetlands (FWS and SSF) consist of a series of 100-gal plastic tubs filled with local soils, gravel, sharp sand and native wetland plants (cattail (Typha spp.), bulrush (Scirpus spp.), dwarf spikerush (Eleocharis)). Feed pumps control hydraulic retention time (HRT) and simple water control structures control the depth of water. The treated water is returned to the existing produced water treatment system. All NPDES discharge limits are met. Observations are included on training RMOTC summer students to do environmental work.

  20. Modelling the impact of a subsurface barrier on groundwater flow in the lower Palar River basin, southern India

    Science.gov (United States)

    Senthilkumar, M.; Elango, L.

    2011-06-01

    Groundwater modelling is widely used as a management tool to understand the behaviour of aquifer systems under different hydrological stresses, whether induced naturally or by humans. The objective of this study was to assess the effect of a subsurface barrier on groundwater flow in the Palar River basin, Tamil Nadu, southern India. Groundwater is supplied to a nearby nuclear power plant and groundwater also supplies irrigation, industrial and domestic needs. In order to meet the increasing demand for groundwater for the nuclear power station, a subsurface barrier/dam was proposed across Palar River to increase the groundwater heads and to minimise the subsurface discharge of groundwater into the sea. The groundwater model used in this study predicted that groundwater levels would increase by about 0.1-0.3 m extending out a distance of about 1.5-2 km from the upstream side of the barrier, while on the downstream side, the groundwater head would lower by about 0.1-0.2 m. The model also predicted that with the subsurface barrier in place the additional groundwater requirement of approximately 13,600 m3/day (3 million gallons (UK)/day) can be met with minimum decline in regional groundwater head.

  1. Study of atrazine degradation in subsurface flow constructed wetland under different salinity.

    Science.gov (United States)

    Lin, Tao; Wen, Yue; Jiang, Lingyan; Li, Jianbo; Yang, Silu; Zhou, Qi

    2008-05-01

    To evaluate the treatment capability of subsurface flow constructed wetland (SFCW) and the effect of salinity on the degradation of atrazine, the degradation of atrazine in SFCW was studied. Under the static condition, the degradation of atrazine in SFCW followed first-order kinetics: c=0.09679 exp(-0.0396t) (c, residue concentration, mg l(-1); t, retention time, d), with a half-life of approximately 17.5 days. The atrazine degradation kinetic functions were established for salinities of 1.5, 3.0, 5.0, 10.0 and 15.0 g l(-1), respectively, which appeared to approach first-order kinetics. The effect of salinity on the atrazine treatment efficiency showed an exponential inhibition: lnk=3.204+0.04991 C (k, degradation constant; C, NaCl concentration, mg l(-1)). The attenuation of atrazine in SFCW cannot be a result of hydrolysis or sorption process. It was considered that some bacteria in the wetland system degraded atrazine into deethylatrazine (DEA) and deisopropylatrazine (DIA) and sequentially into CO(2) and H(2)O. Salinity impacted on the growth of bacteria resulting in a switch of the microbial community. With the increase of salinity, Shannon-Wiener Diversity Index in the SFCW system declined. The relationship between atrazine degradation constant (k) and Shannon Index was established as shown in linear phase, y=-0.07286+0.0363x. The positive correlation between them indicated that microbial community played an important role in the atrazine degradation process.

  2. Enhanced arsenic removals through plant interactions in subsurface-flow constructed wetlands.

    Science.gov (United States)

    Singhakant, Chatchawal; Koottatep, Thammarat; Satayavivad, Jutamaad

    2009-02-01

    Arsenic (As) removal in pilot-scale subsurface-flow constructed wetlands (CWs) was investigated by comparing between CW units with vetiver grasses (CWplanted) and CW units without vetiver grasses (CWunplanted) in order to determine the roles of vetiver grasses affecting As removal. Based on the data obtained from 147 days of experiment, it is apparent that CWplanted units could remove As significantly higher than those of CWunplanted units with approximately 7-14%. Although analysis of As mass balance in CW units revealed that only 0.5-1.0% of total As was found in vetiver grasses, the As retained within bed of the CWplanted units (23.6-29.7 g) was higher than those in the CWunplanted units (21.3-26.8 g) at the end of the experiment, illustrating the effect of vetiver grasses on As accumulation in the CW units. Determination of As in different fractions in the CW bed suggested that the main mechanism of As retention was due mainly to As entrapment into the porous of bed materials (50-57% of total fraction), this mechanism is likely not affected by the presence of vetiver grasses. However, fraction of As-bound in organic matters that could be released from plant roots decomposition indicated the increase adsorption capacity of CW bed. In addition, organic sulfides produced from their root decomposition could help remove As through the precipitation/co-precipitation process. Under reducing condition in those CWplanted units, As could be leached out in the form of iron and manganese-bound complexes.

  3. Desain IPAL Pengolahan Grey Water dengan Teknologi Subsurface Flow Constructed Wetland di Rusunawa Grudo Surabaya

    Directory of Open Access Journals (Sweden)

    Ahmad Safrodin

    2017-01-01

    Full Text Available Pencemaran Lingkungan di Kota Surabaya akan terus meningkat  seiring dengan perkembangan penduduk dan keterbatasan sarana sanitasi yang kurang baik. Pencemaran lingkungan ini didominasi limbah domestik sehingga perlu sistem pengolahan yang efektif dan efisien dalam mendegradasi senyawa polutan. Teknologi Constructed wetland merupakan  sistem  pengolahan  terencana atau terkontrol yang telah didesain dan dibangun menggunakan proses alami yang  melibatkan  vegetasi,  media,  dan  mikroorganisme  untuk  mengolah  air  limbah domestik. Teknologi ini dapat diterapkan untuk skala perumahan baik individu atau secara komunal. Rusunawa Grudo Surabaya merupakan rusun yang belum memiliki IPAL untuk mengolah greywater, sehingga sistem Contructed wetland ini dapat diterapkan untuk meningkatkan kualitas sanitasi lingkungan. Perencanaan sistem Constructed wetland di Rusunawa Grudo Surabaya mempertimbangkan aspek kuantitas dan kualitas air limbah. Kualitas air limbah domestik menunjukkan nilai COD 329.81 mg/L; BOD 182.02 mg/L; dan TSS 103.33 mg/L, sedangkan kuantitas air limbah 33.6 m3/hari. Sistem ini terdiri dari unit ekualisasi, Subsurface Flow Constructed Wetland dengan tanaman Cyperus alternifolius, dan kolam penampung. Hasil perencanaan menunjukkan efisiensi pengolahan seluruh sistem untuk COD, BOD, dan TSS masing-masing sebesar 86%, 85%, dan 88%. Desain sistem IPAL menghasilkan luas permukaan 480 m2, kedalaman bed 0,5 m, beban pada bed (OLR 12.75 gr BOD/m2.hari, beban hidrolik (HLR 0,07 m3/m2.hari dengan waktu tinggal 3 hari. Kualitas efluen yang didapatkan menunjukkan nilai BOD 25 mg/L, COD 48.35 mg/L dan TSS 11.72 mg/L. Dihasilkan standar operasional dan perawatan IPAL dan Biaya investasi seluruh sistem constructed wetland diperkirakan sebesar Rp.412.059.022.

  4. Dynamics of Bacterial Community Abundance and Structure in Horizontal Subsurface Flow Wetland Mesocosms Treating Municipal Wastewater

    Directory of Open Access Journals (Sweden)

    Kristjan Oopkaup

    2016-10-01

    Full Text Available Dynamics of bacterial community abundance and structure of a newly established horizontal subsurface flow (HSSF pilot-scale wetland were studied using high-throughput sequencing and quantitative polymerase chain reaction (PCR methods. Bacterial community abundance increased rapidly within one month and stabilised thereafter in three replicate HSSF constructed wetland (CW mesocosms. The most dominant phylum was Proteobacteria, followed by Bacteroidetes in wetland media biofilms and Firmicutes in influent wastewater. CW bacterial community diversity increased over time and was positively related to the wastewater treatment efficiency. Increase in the abundance of total bacteria in the community was accompanied with the abundance of denitrifying bacteria that promoted nitrate and nitrite removal from the wastewater. During the 150-day study period, similar patterns of bacterial community successions were observed in replicate HSSF CW mesocosms. The data indicate that successions in the bacterial community in HSSF CW are shaped by biotic interactions, with a significant contribution made by external abiotic factors such as influent chemical parameters. Network analysis of the bacterial community revealed that organic matter and nitrogen removal in HSSF CW could be, in large part, allocated to a small subset of tightly interconnected bacterial species. The diversity of bacterial community and abundance of denitrifiers were good predictors of the removal efficiency of ammonia, nitrate and total organic C in HSSF CW mesocosms, while the removal of the seven-day biochemical oxygen demand (BOD7 was best predicted by the abundance of a small set of bacterial phylotypes. The results suggest that nitrogen removal in HSSF CW consist of two main pathways. The first is heterotrophic nitrification, which is coupled with aerobic denitrification and mediated by mixotrophic nitrite-oxidizers. The second pathway is anaerobic denitrification, which leads to gaseous

  5. Performance of a vertical subsurface flow constructed wetland under different operational conditions

    Directory of Open Access Journals (Sweden)

    Sara G. Abdelhakeem

    2016-09-01

    Full Text Available The performance of a vertical subsurface flow constructed wetland (VSSFCW for sewage effluent treatment was studied in an eight month experiment under different operational conditions including: vegetation (the presence or absence of common reeds “Phragmites australis”, media type (gravel or vermiculite, and mode of sewage feeding (continuous or batch. Plants had a significant effect (P < 0.05 on the removal efficiency and mass removal rate of all pollutants, except phosphorous. The average removal efficiencies of chemical oxygen demand (COD, biological oxygen demand (BOD, total suspended solids (TSS, ammonium (NH4 and total-P (TP were 75%, 84%, 75%, 32% and 22% for the planted beds compared to 29%, 37%, 42%, 26% and 17%, respectively, for the unplanted beds. The VSSFCW was ineffective in removing nitrate (NO3. The effect of either media type or feeding mode system on the removal efficiency of COD and BOD was insignificant. Vermiculite media significantly (P < 0.05 increased the efficiency of the wetland in removing NH4, TP and dissolved phosphorous (DP when compared with gravel particularly in the planted beds. The batch mode was more effective in removing TSS and NH4 compared to the continuous mode. Volumetric rate constant (kV was different for various pollutants and significantly increased due to the presence of plants. Media type had no significant effect on the values of kV for COD, BOD and TSS, while kV for NH4 and TP under vermiculite in the planted beds and kV for P in the unplanted beds were significantly higher than those under gravel.

  6. Hierarchical Testing with Automated Document Generation for Amanzi, ASCEM's Subsurface Flow and Reactive Transport Simulator

    Science.gov (United States)

    Moulton, J. D.; Steefel, C. I.; Yabusaki, S.; Castleton, K.; Scheibe, T. D.; Keating, E. H.; Freedman, V. L.

    2013-12-01

    The Advanced Simulation Capabililty for Environmental Management (ASCEM) program is developing an approach and open-source tool suite for standardized risk and performance assessments at legacy nuclear waste sites. These assessments use a graded and iterative approach, beginning with simplified highly abstracted models, and adding geometric and geologic complexity as understanding is gained. To build confidence in this assessment capability, extensive testing of the underlying tools is needed. Since the tools themselves, such as the subsurface flow and reactive-transport simulator, Amanzi, are under active development, testing must be both hierarchical and highly automated. In this presentation we show how we have met these requirements, by leveraging the python-based open-source documentation system called Sphinx with several other open-source tools. Sphinx builds on the reStructured text tool docutils, with important extensions that include high-quality formatting of equations, and integrated plotting through matplotlib. This allows the documentation, as well as the input files for tests, benchmark and tutorial problems, to be maintained with the source code under a version control system. In addition, it enables developers to build documentation in several different formats (e.g., html and pdf) from a single source. We will highlight these features, and discuss important benefits of this approach for Amanzi. In addition, we'll show that some of ASCEM's other tools, such as the sampling provided by the Uncertainty Quantification toolset, are naturally leveraged to enable more comprehensive testing. Finally, we will highlight the integration of this hiearchical testing and documentation framework with our build system and tools (CMake, CTest, and CDash).

  7. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW).

    Science.gov (United States)

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin; Anderson, Bruce; Cheng, Shuiping

    2016-05-15

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg · L(-1)). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (ΦPS II) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Application of subsurface vertical flow constructed wetlands to reject water treatment in dairy wastewater treatment plant.

    Science.gov (United States)

    Dąbrowski, Wojciech; Karolinczak, Beata; Gajewska, Magdalena; Wojciechowska, Ewa

    2017-01-01

    The paper presents the effects of applying subsurface vertical flow constructed wetlands (SS VF) for the treatment of reject water generated in the process of aerobic sewage sludge stabilization in the biggest dairy wastewater treatment plant (WWTP) in Poland. Two SS VF beds were built: bed (A) with 0.65 m depth and bed (B) with 1.0 m depth, planted with reeds. Beds were fed with reject water with hydraulic load of 0.1 m d(-1) in order to establish the differences in treatment efficiency. During an eight-months research period, a high removal efficiency of predominant pollutants was shown: BOD5 88.1% (A) and 90.5% (B); COD 84.5% (A) and 87.5% (B); TSS 87.6% (A) and 91.9% (B); TKN 82.4% (A) and 76.5% (B); N-NH4(+) 89.2% (A) and 85.7% (B); TP 30.2% (A) and 40.6% (B). There were not statistically significant differences in the removal efficiencies between bed (B) with 1.0 m depth and bed (A) with 0.65 m depth. The research indicated that SS VF beds could be successfully applied to reject water treatment in dairy WWTPs. The study proved that the use of SS VF beds in full scale in dairy WWTPs would result in a significant decrease in pollutants' load in reject water. In the analyzed case, decreasing the load of ammonia nitrogen was of greatest importance, as it constituted 58% of the total load treated in dairy WWTP and posed a hazard to the stability of the treatment process.

  9. Nitrogen and COD Removal from Septic Tank Wastewater in Subsurface Flow Constructed Wetlands: Plants Effects.

    Science.gov (United States)

    Collison, R S; Grismer, M E

    2015-11-01

    We evaluated subsurface flow (SSF) constructed wetland treatment performance with respect to organics (COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) wastewater as affected by the presence of plants, substrate "rock" cation exchange capacity (CEC), laboratory versus field conditions and use of synthetic as compared to actual domestic wastewater. This article considers the effects of plants on constructed wetland treatment in the field. Each constructed wetland system was comprised of two beds (2.6 m long by 0.28 m wide and deep filled with ~18 mm crushed lava rock) separated by an aeration tank connected in series. The lava rock had a porosity of ~47% and a CEC of 4 meq/100 gm. One pair of constructed wetland systems was planted with cattails in May 2008, while an adjacent pair of systems remained un-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each constructed wetland system and effluent samples were regularly collected and tested for COD and nitrogen species during four time periods spanning November 2008 through June 2009. These effluent concentrations were tested for statistical differences at the 95% level for individual time periods as well as the overall 6-month period. Organics removal from domestic wastewater was 78.8% and 76.1% in the planted and un-planted constructed wetland systems, respectively, while ammonium removal was 94.5% and 90.2%, respectively. Similarly, organics removal from the synthetic wastewater of equivalent strength was 88.8% and 90.1% for planted and un-planted constructed wetland systems, respectively, while ammonium removal was 96.9% and 97.3%, respectively.

  10. Factors affecting linear alkylbenzene sulfonates removal in subsurface flow constructed wetlands.

    Science.gov (United States)

    Huang, Yuming; LaTorre, Ana; Barceló, Damià; García, Joan; Aguirre, Paula; Mujeriego, Rafael; Bayona, Josep M

    2004-05-01

    The behavior of linear alkylbenzene sulfonate (LAS) and sulfophenyl carboxylate (SPC) biointermediates in a pilot subsurface flow constructed wetland (SFCW) is reported for the first time. The effects of wetland configuration and operation on their treatment efficiency were investigated. The pilot SFCW constituted by eight beds of 55 m2 with different aspect ratios (1 x 1; 1.5 x 1; 2 x 1; 2.5 x 1), two water depths (i.e., 0.47 and 0.27 cm) at 5 cm below surface and two medium sizes (i.e., D60 = 10 mm and 3.5 mm) planted with Phragmites sp. That SFCW pilottreats urban wastewater (i.e., 200 inhabitants) and was operated at four hydraulic loading rates (HLRs) (20, 27, 36, and 45 mm d(-1)). Influent and effluent sampling was carried out from May 2001 to January 2002 with a weekly pattern. Main results were as follows: (i) water depth has a major influence on the performance of SFCW for the LAS removal, and HLR shows significant effect on SPC evolution; (ii) water temperature has a significant effect on the LAS evolution; (iii) biodegradation of LAS and SPC can occur under sulfate-reducing environment and mixed conditions (i.e., sulfate-reducing and denitrification), but aerobic respiration cannot be excluded; and (iv) C13 LAS homologues were generally removed in higher extent than the shorter alkyl chain counterparts. In the most appropriate conditions, LAS and SPC can be biodegraded up to 71% and 11%, respectively, in the pilot SFCW evaluated.

  11. NMR reaction monitoring in flow synthesis

    Directory of Open Access Journals (Sweden)

    M. Victoria Gomez

    2017-02-01

    Full Text Available Recent advances in the use of flow chemistry with in-line and on-line analysis by NMR are presented. The use of macro- and microreactors, coupled with standard and custom made NMR probes involving microcoils, incorporated into high resolution and benchtop NMR instruments is reviewed. Some recent selected applications have been collected, including synthetic applications, the determination of the kinetic and thermodynamic parameters and reaction optimization, even in single experiments and on the μL scale. Finally, software that allows automatic reaction monitoring and optimization is discussed.

  12. Intercomparison of Multiscale Modeling Approaches in Simulating Subsurface Flow and Transport

    Science.gov (United States)

    Yang, X.; Mehmani, Y.; Barajas-Solano, D. A.; Song, H. S.; Balhoff, M.; Tartakovsky, A. M.; Scheibe, T. D.

    2016-12-01

    Hybrid multiscale simulations that couple models across scales are critical to advance predictions of the larger system behavior using understanding of fundamental processes. In the current study, three hybrid multiscale methods are intercompared: multiscale loose-coupling method, multiscale finite volume (MsFV) method and multiscale mortar method. The loose-coupling method enables a parallel workflow structure based on the Swift scripting environment that manages the complex process of executing coupled micro- and macro-scale models without being intrusive to the at-scale simulators. The MsFV method applies microscale and macroscale models over overlapping subdomains of the modeling domain and enforces continuity of concentration and transport fluxes between models via restriction and prolongation operators. The mortar method is a non-overlapping domain decomposition approach capable of coupling all permutations of pore- and continuum-scale models with each other. In doing so, Lagrange multipliers are used at interfaces shared between the subdomains so as to establish continuity of species/fluid mass flux. Subdomain computations can be performed either concurrently or non-concurrently depending on the algorithm used. All the above methods have been proven to be accurate and efficient in studying flow and transport in porous media. However, there has not been any field-scale applications and benchmarking among various hybrid multiscale approaches. To address this challenge, we apply all three hybrid multiscale methods to simulate water flow and transport in a conceptualized 2D modeling domain of the hyporheic zone, where strong interactions between groundwater and surface water exist across multiple scales. In all three multiscale methods, fine-scale simulations are applied to a thin layer of riverbed alluvial sediments while the macroscopic simulations are used for the larger subsurface aquifer domain. Different numerical coupling methods are then applied between

  13. Subsurface Flow Modeling in Single and Dual Continuum Anisotropic Porous Media using the Multipoint Flux Approximation Method

    KAUST Repository

    Negara, Ardiansyah

    2015-05-01

    Anisotropy of hydraulic properties of the subsurface geologic formations is an essential feature that has been established as a consequence of the different geologic processes that undergo during the longer geologic time scale. With respect to subsurface reservoirs, in many cases, anisotropy plays significant role in dictating the direction of flow that becomes no longer dependent only on driving forces like the pressure gradient and gravity but also on the principal directions of anisotropy. Therefore, there has been a great deal of motivation to consider anisotropy into the subsurface flow and transport models. In this dissertation, we present subsurface flow modeling in single and dual continuum anisotropic porous media, which include the single-phase groundwater flow coupled with the solute transport in anisotropic porous media, the two-phase flow with gravity effect in anisotropic porous media, and the natural gas flow in anisotropic shale reservoirs. We have employed the multipoint flux approximation (MPFA) method to handle anisotropy in the flow model. The MPFA method is designed to provide correct discretization of the flow equations for general orientation of the principal directions of the permeability tensor. The implementation of MPFA method is combined with the experimenting pressure field approach, a newly developed technique that enables the solution of the global problem breaks down into the solution of multitude of local problems. The numerical results of the study demonstrate the significant effects of anisotropy of the subsurface formations. For the single-phase groundwater flow coupled with the solute transport modeling in anisotropic porous media, the results shows the strong impact of anisotropy on the pressure field and the migration of the solute concentration. For the two-phase flow modeling with gravity effect in anisotropic porous media, it is observed that the buoyancy-driven flow, which emerges due to the density differences between the

  14. Modelling near subsurface temperature with mixed type boundary condition for transient air temperature and vertical groundwater flow

    Indian Academy of Sciences (India)

    Rajeev Ranjan Kumar; D V Ramana; R N Singh

    2012-10-01

    Near-subsurface temperatures have signatures of climate change. Thermal models of subsurface have been constructed by prescribing time dependent Dirichlet type boundary condition wherein the temperature at the soil surface is prescribed and depth distribution of temperature is obtained. In this formulation it is not possible to include the relationship between air temperatures and the temperature of soil surface. However, if one uses a Robin type boundary condition, a transfer coefficient relates the air and soil surface temperatures which helps to determine both the temperature at the surface and at depth given near surface air temperatures. This coefficient is a function of meteorological conditions and is readily available. We have developed such a thermal model of near subsurface region which includes both heat conduction and advection due to groundwater flows and have presented numerical results for changes in the temperature–depth profiles for different values of transfer coefficient and groundwater flux. There are significant changes in temperature and depth profiles due to changes in the transfer coefficient and groundwater flux. The analytical model will find applications in the interpretation of the borehole geothermal data to extract both climate and groundwater flow signals.

  15. Optimal design for problems involving flow and transport phenomena in saturated subsurface systems

    Science.gov (United States)

    Mayer, Alex S.; Kelley, C. T.; Miller, Cass T.

    Estimation problems arise routinely in subsurface hydrology for applications that range from water resources management to water quality protection to subsurface restoration. Interest in optimal design of such systems has increased over the last two decades and this area is considered an important and active area of research. In this work, we review the state of the art, assess important challenges that must be resolved to reach a mature level of understanding, and summarize some promising approaches that might help meet some of the challenges. While much has been accomplished to date, we conclude that more work remains before comprehensive, efficient, and robust solution methods exist to solve the most challenging applications in subsurface science. We suggest that future directions of research include the application of direct search solution methods, and developments in stochastic and multi-objective optimization. We present a set of comprehensive test problems for use in the research community as a means for benchmarking and comparing optimization approaches.

  16. Surface-subsurface flow modeling: an example of large-scale research at the new NEON user facility

    Science.gov (United States)

    Powell, H.; McKnight, D. M.

    2009-12-01

    Climate change is predicted to alter surface-subsurface interactions in freshwater ecosystems. These interactions are hypothesized to control nutrient release at diel and seasonal time scales, which may then exert control over epilithic algal growth rates. The mechanisms underlying shifts in complex physical-chemical-biological patterns can be elucidated by long-term observations at sites that span hydrologic and climate gradients across the continent. Development of the National Ecological Observatory Network (NEON) will provide researchers the opportunity to investigate continental-scale patterns by combining investigator-driven measurements with Observatory data. NEON is a national-scale research platform for analyzing and understanding the impacts of climate change, land-use change, and invasive species on ecology. NEON features sensor networks and experiments, linked by advanced cyberinfrastructure to record and archive ecological data for at least 30 years. NEON partitions the United States into 20 ecoclimatic domains. Each domain hosts one fully instrumented Core Aquatic site in a wildland area and one Relocatable site, which aims to capture ecologically significant gradients (e.g. landuse, nitrogen deposition, urbanization). In the current definition of NEON there are 36 Aquatic sites: 30 streams/rivers and 6 ponds/lakes. Each site includes automated, in-situ sensors for groundwater elevation and temperature; stream flow (discharge and stage); pond water elevation; atmospheric chemistry (Tair, barometric pressure, PAR, radiation); and surface water chemistry (DO, Twater, conductivity, pH, turbidity, cDOM, nutrients). Groundwater and surface water sites shall be regularly sampled for selected chemical and isotopic parameters. The hydrologic and geochemical monitoring design provides basic information on water and chemical fluxes in streams and ponds and between groundwater and surface water, which is intended to support investigator-driven modeling studies

  17. Biological mechanisms associated with triazophos (TAP) removal by horizontal subsurface flow constructed wetlands (HSFCW)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Juan; Feng, Yuqin; Dai, Yanran; Cui, Naxin [State Key Laboratory of Pollution Control and ResourceReuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Anderson, Bruce [Department of Civil Engineering, Queen' s University, Kingston K7L3N6 (Canada); Cheng, Shuiping, E-mail: shpcheng@tongji.edu.cn [State Key Laboratory of Pollution Control and ResourceReuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

    2016-05-15

    Triazophos (TAP) is a widely used pesticide that is easily accumulated in the environment due to its relatively high stability: this accumulation from agricultural runoff results in potential hazards to aquatic ecosystems. Constructed wetlands are generally considered to be an effective technology for treating TAP polluted surface water. However, knowledge about the biological mechanisms of TAP removal is still lacking. This study investigates the responses of a wetland plant (Canna indica), substrate enzymes and microbial communities in bench-scale horizontal subsurface-flow constructed wetlands (HSCWs) loaded with different TAP concentrations (0, 0.1, 0.5 and 5 mg·L{sup −1}). The results indicate that TAP stimulated the activities of superoxide dismutase (SOD) and peroxidase (POD) in the roots of C. indica. The highest TAP concentrations significantly inhibited photosynthetic activities, as shown by a reduced effective quantum yield of PS II (Φ{sub PSII}) and lower electron transport rates (ETR). However, interestingly, the lower TAP loadings exhibited some favorable effects on these two variables, suggesting that C. indica is a suitable species for use in wetlands designed for treatment of low TAP concentrations. Urease and alkaline phosphatase (ALP) in the wetland substrate were activated by TAP. Two-way ANOVA demonstrated that urease activity was influenced by both the TAP concentrations and season, while acidphosphatase (ACP) only responded to seasonal variations. Analysis of high throughput sequencing of 16S rRNA revealed seasonal variations in the microbial community structure of the wetland substrate at the phylum and family levels. In addition, urease activity had a greater correlation with the relative abundance of some functional microbial groups, such as the Bacillaceae family, and the ALP and ACP may be influenced by the plant more than substrate microbial communities. - Highlights: • Physiological responses of the wetland plant to triazophos

  18. A physically-based integrated numerical model for flow,upland erosion,and contaminant transport in surface-subsurface systems

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This paper presents a physically-based integrated hydrologic model that can simulate the rain-fall-induced 2D surface water flow, 3D variably saturated subsurface flow, upland soil erosion and transport, and contaminant transport in the surface-subsurface system of a watershed. The model couples surface and subsurface flows based on the assumption of continuity conditions of pressure head and exchange flux at the ground, considering infiltration and evapotranspiration. The upland rill/interrill soil erosion and transport are simulated using a non-equilibrium transport model. Contaminant transport in the integrated surface and subsurface domains is simulated using advection-diffusion equations with mass changes due to sediment sorption and desorption and exchanges between two domains due to infiltration, diffusion, and bed change. The model requires no special treatments at the interface of upland areas and streams and is suitable for wetland areas and agricultural watersheds with shallow streams.

  19. Enhanced Geothermal Systems Research and Development: Models of Subsurface Chemical Processes Affecting Fluid Flow

    Energy Technology Data Exchange (ETDEWEB)

    Moller, Nancy; Weare J. H.

    2008-05-29

    Successful exploitation of the vast amount of heat stored beneath the earth’s surface in hydrothermal and fluid-limited, low permeability geothermal resources would greatly expand the Nation’s domestic energy inventory and thereby promote a more secure energy supply, a stronger economy and a cleaner environment. However, a major factor limiting the expanded development of current hydrothermal resources as well as the production of enhanced geothermal systems (EGS) is insufficient knowledge about the chemical processes controlling subsurface fluid flow. With funding from past grants from the DOE geothermal program and other agencies, we successfully developed advanced equation of state (EOS) and simulation technologies that accurately describe the chemistry of geothermal reservoirs and energy production processes via their free energies for wide XTP ranges. Using the specific interaction equations of Pitzer, we showed that our TEQUIL chemical models can correctly simulate behavior (e.g., mineral scaling and saturation ratios, gas break out, brine mixing effects, down hole temperatures and fluid chemical composition, spent brine incompatibilities) within the compositional range (Na-K-Ca-Cl-SO4-CO3-H2O-SiO2-CO2(g)) and temperature range (T < 350°C) associated with many current geothermal energy production sites that produce brines with temperatures below the critical point of water. The goal of research carried out under DOE grant DE-FG36-04GO14300 (10/1/2004-12/31/2007) was to expand the compositional range of our Pitzer-based TEQUIL fluid/rock interaction models to include the important aluminum and silica interactions (T < 350°C). Aluminum is the third most abundant element in the earth’s crust; and, as a constituent of aluminosilicate minerals, it is found in two thirds of the minerals in the earth’s crust. The ability to accurately characterize effects of temperature, fluid mixing and interactions between major rock-forming minerals and hydrothermal and

  20. Damköhler number design method to avoid clogging of subsurface flow constructed wetlands by heterotrophic biofilms.

    Science.gov (United States)

    Austin, D; Maciolek, D; Davis, B; Wallace, S

    2007-01-01

    Clogging of subsurface flow (SSF) treatment wetlands from excess biofilm growth is a design problem for which only empirical guidelines exist. A method is proposed to systematically analyse this type of clogging as a design tool. In recognition of the physical reality that most SSF treatment wetland processes are a function of biofilm surface area, a Damköhler number (Da) definition based on aggregate specific surface area is used to investigate a method of predicting clogging induced by heterotrophic biofilms growing on treatment media.

  1. Initial Survey Instructions for Spring Water Monitoring : Flow

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Initial survey instructions for the Spring Water Monitoring - Flow 1.02 survey at Fish Springs National Wildlife Refuge. This coop baseline monitoring survey has...

  2. A multiple-point geostatistical method for characterizing uncertainty of subsurface alluvial units and its effects on flow and transport

    Science.gov (United States)

    Cronkite-Ratcliff, C.; Phelps, G.A.; Boucher, A.

    2012-01-01

    This report provides a proof-of-concept to demonstrate the potential application of multiple-point geostatistics for characterizing geologic heterogeneity and its effect on flow and transport simulation. The study presented in this report is the result of collaboration between the U.S. Geological Survey (USGS) and Stanford University. This collaboration focused on improving the characterization of alluvial deposits by incorporating prior knowledge of geologic structure and estimating the uncertainty of the modeled geologic units. In this study, geologic heterogeneity of alluvial units is characterized as a set of stochastic realizations, and uncertainty is indicated by variability in the results of flow and transport simulations for this set of realizations. This approach is tested on a hypothetical geologic scenario developed using data from the alluvial deposits in Yucca Flat, Nevada. Yucca Flat was chosen as a data source for this test case because it includes both complex geologic and hydrologic characteristics and also contains a substantial amount of both surface and subsurface geologic data. Multiple-point geostatistics is used to model geologic heterogeneity in the subsurface. A three-dimensional (3D) model of spatial variability is developed by integrating alluvial units mapped at the surface with vertical drill-hole data. The SNESIM (Single Normal Equation Simulation) algorithm is used to represent geologic heterogeneity stochastically by generating 20 realizations, each of which represents an equally probable geologic scenario. A 3D numerical model is used to simulate groundwater flow and contaminant transport for each realization, producing a distribution of flow and transport responses to the geologic heterogeneity. From this distribution of flow and transport responses, the frequency of exceeding a given contaminant concentration threshold can be used as an indicator of uncertainty about the location of the contaminant plume boundary.

  3. Continuous 'Passive' flow-proportional monitoring of drainage using a new modified Sutro weir (MSW) unit.

    Science.gov (United States)

    Vendelboe, Anders Lindblad; Rozemeijer, Joachim; de Jonge, Lis Wollesen; de Jonge, Hubert

    2016-03-01

    In view of their crucial role in water and solute transport, enhanced monitoring of agricultural subsurface drain tile systems is important for adequate water quality management. However, existing monitoring techniques for flow and contaminant loads from tile drains are expensive and labour intensive. The aim of this study was to develop a cost-effective and simple method for monitoring loads from tile drains. The Flowcap is a modified Sutro weir (MSW) unit that can be attached to the outlet of tile drains. It is capable of registering total flow, contaminant loads and flow-averaged concentrations. The MSW builds on a modern passive sampling technique that responds to hydraulic pressure and measures average concentrations over time (days to months) for various substances. Mounting the samplers in the MSW allowed a flow-proportional part of the drainage to be sampled. Laboratory testing yielded high linear correlation between the accumulated sampler flow, q total, and accumulated drainage flow, Q total (r (2) > 0.96). The slope of these correlations was used to calculate the total drainage discharge from the sampled volume, and therefore contaminant load. A calibration of the MSW under controlled laboratory condition was needed before interpretation of the monitoring results was possible. The MSW does not require a shed, electricity, or maintenance. This enables large-scale monitoring of contaminant loads via tile drains, which can improve contaminant transport models and yield valuable information for the selection and evaluation of mitigation options to improve water quality. Results from this type of monitoring can provide data for the evaluation and optimisation of best management practices in agriculture in order to produce the highest yield without water quality and recipient surface waters being compromised.

  4. Subsurface thermal regime to delineate the paleo-groundwater flow system in an arid area, Al Kufra, Libya

    Directory of Open Access Journals (Sweden)

    Zenhom El-Said Salem

    2016-12-01

    Full Text Available The purpose of this study was to understand the groundwater flow system in Al Kufra basin, Libya, as a case study of arid areas using subsurface temperature. The temperature-depth profiles and water levels were measured in eight boreholes in the area. Well 6 is considered a recharge type profile with low geothermal gradient (0.0068 °C/m and an estimated paleo-temperature around 19.5 °C. The other profiles are of discharge type with higher geothermal gradient (0.0133 to 0.0166 °C/m. The constructed horizontal 2D distribution maps of the hydraulic heads and the subsurface temperature measurements reveal that the main recharge area is located to the south with low temperature while the main discharge area is located to the north with higher temperature. Vertical 2D distribution maps show that location of well 4 has low hydraulic heads and higher temperature indicating that the fault defined in the area may have affected the groundwater flow system. The estimated groundwater flux ranges from 0.001 to 0.1 mm/day for the recharge area and from −0.3 to −0.7 mm/day in average in the discharge area.

  5. Effect of physico-chemical pretreatment on the removal efficiency of horizontal subsurface-flow constructed wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Caselles-Osorio, Aracelly [Environmental Engineering Division, Hydraulics, Coastal and Environmental Engineering Department, Technical University of Catalonia, c/Jordi Girona 1-3, Modul D-1, 08034 Barcelona (Spain); Department of Biology, Atlantic University, Km 7 Higway Old Colombia Port, Barranquilla (Colombia); Garcia, Joan [Environmental Engineering Division, Hydraulics, Coastal and Environmental Engineering Department, Technical University of Catalonia, c/Jordi Girona 1-3, Modul D-1, 08034 Barcelona (Spain)]. E-mail: joan.garcia@upc.edu

    2007-03-15

    In this study, we tested the effect of a physico-chemical pretreatment on contaminant removal efficiency in two experimental horizontal subsurface-flow constructed wetlands (SSF CWs). One SSF CW was fed with settled urban wastewater, whereas the other with the same wastewater after it had undergone a physico-chemical pretreatment. The SSF CWs were operated with three different hydraulic retention times. During the experiments the effluent concentrations of COD, ammonia N and sulfate were very similar, and, therefore, the physico-chemical pretreatment did not improve the quality of the effluents. COD removal efficiency (as percentage or mass surface removal rate) was slightly greater in the SSF CW fed with pretreated wastewater. Ammonia N removal efficiency was, in general, similar in both SSF CWs and very high (80-90%). At the end of the experiments it was observed that in the SSF CW fed with settled wastewater the hydraulic conductivity decreased by a 20%. - A physico-chemical pretreatment may help to reduce the risk of clogging of subsurface-flow constructed wetlands.

  6. Subsurface thermal regime to delineate the paleo-groundwater flow system in an arid area, Al Kufra, Libya

    Science.gov (United States)

    Salem, Zenhom El-Said

    2016-12-01

    The purpose of this study was to understand the groundwater flow system in Al Kufra basin, Libya, as a case study of arid areas using subsurface temperature. The temperature-depth profiles and water levels were measured in eight boreholes in the area. Well 6 is considered a recharge type profile with low geothermal gradient (0.0068 °C/m) and an estimated paleo-temperature around 19.5 °C. The other profiles are of discharge type with higher geothermal gradient (0.0133 to 0.0166 °C/m). The constructed horizontal 2D distribution maps of the hydraulic heads and the subsurface temperature measurements reveal that the main recharge area is located to the south with low temperature while the main discharge area is located to the north with higher temperature. Vertical 2D distribution maps show that location of well 4 has low hydraulic heads and higher temperature indicating that the fault defined in the area may have affected the groundwater flow system. The estimated groundwater flux ranges from 0.001 to 0.1 mm/day for the recharge area and from -0.3 to -0.7 mm/day in average in the discharge area.

  7. Invited Article: In situ comparison of passive radon-thoron discriminative monitors at subsurface workplaces in Hungary

    Science.gov (United States)

    Kávási, Norbert; Vigh, Tamás; Németh, Csaba; Ishikawa, Tetsuo; Omori, Yasutaka; Janik, Miroslaw; Yonehara, Hidenori

    2014-02-01

    During a one-year long measurement period, radon and thoron data obtained by two different passive radon-thoron discriminative monitors were compared at subsurface workplaces in Hungary, such as mines (bauxite and manganese ore) and caves (medical and touristic). These workplaces have special environmental conditions, such as, stable and high relative humidity (100%), relatively stable temperature (12°C-21°C), low or high wind speed (max. 2.4 m s-1) and low or elevated aerosol concentration (130-60 000 particles m-3). The measured radon and thoron concentrations fluctuated in a wide range among the different workplaces. The respective annual average radon concentrations and their standard deviations (in brackets) measured by the passive radon-thoron discriminative monitor with cellulose filter (CF) and the passive radon-thoron discriminative monitor with sponge filter (SF) were: 350(321) Bq m-3 and 550(497) Bq m-3 in the bauxite mine; 887(604) Bq m-3 and 1258(788) Bq m-3 in the manganese ore mine; 2510(2341) Bq m-3 and 3403(3075) Bq m-3 in the medical cave (Hospital Cave of Tapolca); and 6239(2057) Bq m-3 and 8512(1955) Bq m-3 in the touristic cave (Lake Cave of Tapolca). The respective average thoron concentrations and their standard deviation (in brackets) measured by CF and SF monitors were: 154(210) Bq m-3 and 161(148) Bq m-3 in the bauxite mine; 187(191) Bq m-3 and 117(147) Bq m-3 in the manganese-ore mine; 360(524) Bq m-3 and 371(789) Bq m-3 in the medical cave (Hospital Cave of Tapolca); and 1420(1184) Bq m-3 and 1462(3655) Bq m-3 in the touristic cave (Lake Cave of Tapolca). Under these circumstances, comparison of the radon data for the SF and CF monitors showed the former were consistently 51% higher in the bauxite mine, 38% higher in the manganese ore mine, and 34% higher in the caves. Consequently, correction is required on previously obtained radon data acquired by CF monitors at subsurface workplaces to gain comparable data for SF monitors. In the

  8. Exploring the role of mixing between subsurface flow paths on transit time distributions using a Lagrangian model

    Science.gov (United States)

    Zehe, Erwin; Jackisch, Conrad; Rodriguez, Nicolas; Klaus, Julian

    2017-04-01

    Only a minute amount of global fresh water is stored in the unsaturated zone. Yet this tiny compartment controls soil microbial activity and associated trace gas emissions, transport and transformations of contaminants, plant productivity, runoff generation and groundwater recharge. To date, the processes controlling renewal and age of different fractions of the soil water stock are far from being understood. Current theories and process concepts were largely inferred either from over-simplified laboratory experiments, or non-exhaustive point observations and tracer data in the field. Tracer data provide key but yet integrated information about the distribution of travel times of the tracer molecules to a certain depth or on their travel depth distribution within a given time. We hence are able to observe the "effect" of soil structure i.e. partitioning of infiltrating water between fast preferential and slow flow paths and imperfect subsequent mixing between these flow paths in the subsurface and the related plant water uptake. However, we are not able to study the "cause" - because technologies for in-situ observations of flow, flow path topology and exchange processes at relevant interfaces have up to now not been at hand. In the present study we will make use of a Lagrangian model for subsurface water dynamics to explore how subsurface heterogeneity and mixing among different storage fractions affects residence time distribution in the unsaturated zone in a forward approach. Soil water is represented by particles of constant mass, which travel according to the Itô form of the Fokker Planck equation. The model concept builds on established soil physics by estimating the drift velocity and the diffusion term based on the soil water characteristics. The model has been shown to simulate capillary driven soil moisture dynamics in good accordance with a) the Richards equation and b) observed soil moisture data in different soil. The particle model may furthermore

  9. Combining dual-continuum approach with diffusion wave model to include a preferential flow component in hillslope scale modeling of shallow subsurface runoff

    Science.gov (United States)

    Dusek, Jaromir; Vogel, Tomas; Dohnal, Michal; Gerke, Horst H.

    2012-08-01

    In the absence of overland flow, shallow subsurface runoff is one of the most important mechanisms determining hydrological responses of headwater catchments to rainstorms. Subsurface runoff can be triggered by preferential flow of infiltrating water frequently occurring in heterogeneous and structured soils as a basically one-dimensional (1D) vertical process. Any attempt to include effects of preferential flow in hydrological hillslope studies is limited by the fact that the thickness of the permeable soil is mostly small compared to the length of the hillslope. The objective of this study is to describe preferential flow effects on hillslope-scale subsurface runoff by combining a 1D vertical dual-continuum approach with a 1D lateral flow equation. The 1D vertical flow of water in a variably saturated soil is described by a coupled set of Richards' equations and the 1D saturated lateral flow of water on less permeable bedrock by the diffusion wave equation. The numerical solution of the combined model was used to study rainfall-runoff events on the Tomsovska hillslope by comparing simulated runoff with observed trench discharge data. The dual-continuum model generated the observed rapid runoff response, which served as an input for the lateral flow model. The diffusion wave model parameters (i.e., length of the contributing hillslope, effective porosity, and effective hydraulic conductivity) indicate that the hillslope length that contributed to subsurface drainage is relatively short (in the range of 25-50 m). Significant transformation of the 1D vertical inflow signal by lateral flow is expected for longer hillslopes, smaller effective conductivities, and larger effective porosities. The physically-based combined modeling approach allows for a consistent description of both preferential flow in a 1D vertical soil profile and lateral subsurface hillslope flow in the simplest way.

  10. Continuous monitoring of water flow and solute transport using vadose zone monitoring technology

    Science.gov (United States)

    Dahan, O.

    2009-04-01

    contaminant transport in various hydrological and geological setups. These include floodwater infiltration in arid environments, land use impact on groundwater quality, and control of remediation process in a contaminated vadose zone. The data which is collected by the VMS allows direct measurements of flow velocities and fluxes in the vadose zone while continuously monitoring the chemical evolution of the percolating water. While real time information on the hydrological and chemical properties of the percolating water in the vadose is essential to prevent groundwater contamination it is also vital for any remediation actions. Remediation of polluted soils and aquifers essentially involves manipulation of surface and subsurface hydrological, physical and biochemical conditions to improve pollutant attenuation. Controlling the biochemical conditions to enhance biodegradation often includes introducing degrading microorganisms, applying electron donors or acceptors, or adding nutrients that can promote growth of the desired degrading organisms. Accordingly real time data on the hydrological and chemical properties of the vadose zone may be used to select remediation strategies and determine its efficiency on the basis of real time information.

  11. Mathematical modeling of diffuse flow in seafloor hydrothermal systems: The potential extent of the subsurface biosphere at mid-ocean ridges

    Science.gov (United States)

    Lowell, R. P.; Houghton, J. L.; Farough, A.; Craft, K. L.; Larson, B. I.; Meile, C. D.

    2015-09-01

    We describe a variety of one- and two-dimensional mathematical modeling approaches to characterizing diffuse flow circulation at mid-ocean ridge hydrothermal systems. The goal is to estimate the potential extent of the sub-seafloor microbial biosphere based on subsurface contours of the 120 °C isotherm as determined from the various models. The models suggest that the sub-seafloor depth for microbial life may range from less than 1 m in some places to the thickness of crustal layer 2A of ∼ 500 m in others. This depth depends primarily on how diffuse flow is driven. The 120 °C isotherm tends to be much deeper if diffuse flow is induced as boundary layer flow near high-temperature plumes, than if it results from conductive cooling or mixing near the seafloor. Because the heat flow alone may not allow identification of the flow regime in the subsurface, we highlight the use of chemical tracers as an additional constraint that sheds light into the flow and reaction patterns associated with vents. We use thermodynamic modeling, which connects the temperature of the diffuse fluid to its chemical composition. As the temperature-composition relationships differ for mixing versus conductive heating and cooling, the fluid geochemistry can shed light on subsurface transport. Using methane as an example, the geochemical models indicate subsurface microbial methane production and consumption in different regions of the vent field near EPR 9 °50‧ N.

  12. Controlling Fluid Flow in the Subsurface through Ureolysis-Controlled Mineral Precipitation

    Science.gov (United States)

    Gerlach, R.; Phillips, A. J.; Cunningham, A. B.; Spangler, L.

    2016-12-01

    In situ urea hydrolysis has been used by us successfully to manipulate the carbonate alkalinity and control the precipitation of carbonate minerals. Urea hydrolysis can be promoted using microbial cells, enzymes or thermal energy. This technology can be used to mitigate leakage pathways, seal fractures or control fluid transport in the subsurface in hydrocarbon production, enhanced geothermal energy storage, carbon sequestration, nuclear waste disposal, etc. We have completed two field demonstrations of the urea hydrolysis-controlled in situ mineral precipitation technology. The first demonstration showed fracture sealing was possible in a sandstone formation approx. 1120' below ground surface (bgs) and that the fracture had increased resistance to re-fracturing after mineralization treatment. The second field demonstration was performed in a well with an identified channel in the cement near the wellbore at approx. 1020' bgs. The in situ mineralization treatment resulted in reduced pressure decay during shut in periods and reduced injectivity. In addition, a noticeable difference was observed in the solids percentage in the ultrasonic imaging logs before and after biomineralization treatment. The presentation will summarize and put into context the field and our recent laboratory research focusing on permeability manipulation using the in situ ureolysis-driven mineralization technology under ambient and subsurface pressure conditions. We have demonstrated permeability reductions of 3-6 orders of magnitude in 100 µm to 4mm gaps between shale, sandstone and cement/steel interfaces.

  13. Low-dimensional modeling of hillslope subsurface flow: Relationship between rainfall, recharge, and unsaturated storage dynamics

    NARCIS (Netherlands)

    Hilberts, A.G.J.; Troch, P.A.A.; Paniconi, C.; Boll, J.

    2007-01-01

    We present a coupling between the one-dimensional Richards equation for vertical unsaturated flow and the one-dimensional hillslope-storage Boussinesq equation (HSB) for lateral saturated flow along complex hillslopes. Here the capillary fringe is included in the flow domain as an integral part of t

  14. Monitoring Subsurface Changes with Active Sources%人工震源地下介质变化动态监测

    Institute of Scientific and Technical Information of China (English)

    王宝善; 王伟涛; 葛洪魁; 徐平; 王彬

    2011-01-01

    To provide images of Earth interior and their temporal variations are main tasks for geophysicists. Comparing to our understanding of the static structure, we are still lacking in the understanding of the temporal var iations of the subsurface. Recently, with the accumulation of observation data, repeated earthquakes and ambient noises are used to monitor subsurface changes. The resolutions and precisions of passive source monitoring are limit ed by the spatial and temporal distributions of sources. Monitoring subsurface changes with seismic wave generated by artificial sources naturally becames another goal to pursue. We systematically describe recent advances in active source monitoring at various scales. In this review, we also introduce cross-correlation based time delay estimation and its precision limitation. The precision of time delay estimation is limited by the repeatability of source, signal to-noise ratio and bandwidth of recorded signals. And seismic sources with large capacity and high repeatability are preferred for active monitoring. Advantages and disadvantages of different sources are compared in this review. According to the comparison, we suggest that the airgun source is superior to other sources for the purpose of active monitoring. Techniques as waveform stacking, coda wave interferometry and their application in active monitoring are also introduced. Waveform stacking can be used to enhance the signal-to-noise ratio and facilitate the phase identificafion. Coda wave travels longer and is more sensitive to subsurface changes than direct waves. Therefore,coda wave interferometry technique can be used to detect subtle variations. With the development of techniques for signal excitation, recording and processing, it is now possible to conduct large scale active subsurface monitoring. Relevant researches have broad potential applications to such fields as natural disaster mitigation and resource exploration.%成像地球内部介质结构及其

  15. 3-D reconstructions of subsurface Pleistocene basalt flows from paleomagnetic inclination data and 40Ar/39Ar ages in the southern part of the Idaho National Laboratory (INL), Idaho (USA)

    Science.gov (United States)

    Hodges, Mary K.; Champion, Duane E.; Turrin, B.D.; Swisher, C. C.

    2012-01-01

    The U. S. Geological Survey, in cooperation with the U.S. Department of Energy, is mapping the distribution of basalt flows and sedimentary interbeds at the Idaho National Laboratory in three dimensions to provide data for refining numerical models of groundwater flow and contaminant transport in the eastern Snake River Plain aquifer. Paleomagnetic inclination and polarity data from basalt samples from 47 coreholes are being used to create a three-dimensional (3-D) model of the subsurface of the southern part of the INL. Surface and sub-surface basalt flows can be identified in individual cores and traced in three dimensions on the surface and in the subsurface for distances of more than 20 km using a combination of paleomagnetic, stratigraphic, and 40Ar/39Ar data. Eastern Snake River Plain olivine tholeiite basalts have K2O contents of 0.2 to 1.0 weight per cent. In spite of the low-K content, high-precision 40Ar/39Ar ages were obtained by applying a protocol that employs short irradiation times (minimizing interferences from Ca derived 36Ar), frequent measurement of various size atmospheric Ar pipettes to monitor and correct for temporal variation, and signal size dependent nonlinearity in spectrometer mass bias, resulting in age dates with resolution generally between 2 to 10% of the age. 3-D models of subsurface basalt flows are being used to: (1) Estimate eruption volumes; (2) locate the approximate vent areas and extent of sub-surface flows; and (3) Help locate high and low transmissivity zones. Results indicate that large basalt eruptions (>3 km3) occurred at and near the Central Facilities Area between 637 ka and 360 ka; at and near the Radioactive Waste Management Complex before 540 ka; and north of the Naval Reactors Facility at about 580 ka. Since about 360 ka, large basalt flows have erupted along the Arco-Big Southern Butte Volcanic Rift Zone and the Axial Volcanic Zone, and flowed northerly towards the Central Facilities Area. Basalt eruptions shifted

  16. Two decades of temperature-time monitoring experiment: air - ground surface - shallow subsurface interactions

    Science.gov (United States)

    Cermak, Vladimir; Dedecek, Petr; Safanda, Jan; Kresl, Milan

    2014-05-01

    Long-term observations (1994-2013) of air and shallow ground temperatures at borehole Prague-Sporilov (50º02'28.5"E, 14º28'40.2"N, 274 m a.s.l.) have been thoroughly analyzed to understand the relationship between these quantities and to describe the mechanism of heat transport at the land-atmosphere boundary layer. Data provided a surprisingly small mean ground-air temperature offset of only 0.31 K with no clear annual course and with the offset value changing irregularly even on a daily scale. Such value is substantially lower than similar values (1-2 K and more) found elsewhere, but may well characterize a mild temperate zone, when all so far available information referred rather to southern locations. Borehole data were correlated with similar observations in a polygon-site under four types of surface conditions (grass, soil, sand and asphalt) completed with registration of meteorological variables (wind direction & velocity, air & soil humidity, direct & reflected solar radiation, precipitation and snow cover). The "thermal orbits" technique proved to be an effective tool for the fast qualitative diagnostics of the thermal regime in the subsurface (conductive versus non-conductive).

  17. Modelling Water Flow, Heat Transport, Soil Freezing and Thawing, and Snow Processes in a Clayey, Subsurface Drained Agricultural Field

    Science.gov (United States)

    Warsta, L.; Turunen, M.; Koivusalo, H. J.; Paasonen-Kivekäs, M.; Karvonen, T.; Taskinen, A.

    2012-12-01

    Simulation of hydrological processes for the purposes of agricultural water management and protection in boreal environment requires description of winter time processes, including heat transport, soil freezing and thawing, and snow accumulation and melt. Finland is located north of the latitude of 60 degrees and has one third to one fourth of the total agricultural land area (2.3 milj. ha) on clay soils (> 30% of clay). Most of the clayey fields are subsurface drained to provide efficient drainage and to enable heavy machines to operate on the fields as soon as possible after the spring snowmelt. Generation of drainflow and surface runoff in cultivated fields leads to nutrient and sediment load, which forms the major share of the total load reaching surface waters at the national level. Water, suspended sediment, and soluble nutrients on clayey field surface are conveyed through the soil profile to the subsurface drains via macropore pathways as the clayey soil matrix is almost impermeable. The objective of the study was to develop the missing winter related processes into the FLUSH model, including soil heat transport, snow pack simulation and the effects of soil freezing and thawing on the soil hydraulic conductivity. FLUSH is an open source (MIT license), distributed, process-based model designed to simulate surface runoff and drainflow in clayey, subsurface drained agricultural fields. 2-D overland flow is described with the diffuse wave approximation of the Saint Venant equations and 3-D subsurface flow with a dual-permeability model. Both macropores and soil matrix are simulated with the Richards equation. Soil heat transport is described with a modified 3-D convection-diffusion equation. Runoff and groundwater data was available from different periods from January 1994 to April 1999 measured in a clayey, subsurface drained field section (3.6 ha) in southern Finland. Soil temperature data was collected in two locations (to a depth of 0.8 m) next to the

  18. Subsurface Structure and Fluid Flow Analysis Using Geophysical Methods in the Geothermal Manifestation Area of Paguyangan, Brebes, Central Java

    Directory of Open Access Journals (Sweden)

    Agus Seyawan

    2016-11-01

    Full Text Available The indication of an active geothermal system is shown by the presence of surface manifestations such as the hot spring in Kedungoleng, Paguyangan, Brebes, Central Java. The temperature of the largest hot spring reaches 74o C and there is an assumption that this is an outflow of Mount Slamet geothermal system. DC-resistivity, Spontaneous Potential (SP and Shallow Surface Temperature surveys were conducted to determine the subsurface structure as well as its correlation with the distribution of thermal fluid flow and shallow surface temperature. The subsurface resistivity has been investigated using 5 points of the Schlumberger configuration with 400 m separation for each point. For the fluid and temperature pattern, a measurement using 15 m interval in 3 lines of conducting fixed electrode configuration has been carried out, along with a 75 cm of depth of temperature measurement around the manifestation area. The thermal fluid is assumed by the low resistivity of 0.756 to 6.91Ωm and this indicates sandstone that has permeable characteristic. The fluid flows in two layers of Sandstone at more than 10 meter from surface of the first layer. Accordingly, the SP values have a range between -11- 11 mV and a depth interval of 13.42- 28.75 m and the distribution of temperature is between 24o-70oC at a tilting range of 46.06o-12.60o. Hence it can be inferred that the thermal fluid moves in the Northwest direction and is controlled by a fault structure stretching from Northwest to Southeast. Article History: Received Feb 3, 2016; Received in revised form July 11, 2016; Accepted August 13, 2016; Available online How to Cite This Article: Setyawan, A., Triahadini, A., Yuliananto, Y., Aribowo, Y., and Widiarso, D.A. (2016 Subsurface Structure and Fluid Flow Analyses Using Geophysical Methods in Geothermal Manifestation Area of Paguyangan, Brebes, Central Java. Int. Journal of Renewable Energy Development, 5(3, 171-177. http://dx.doi.org/10.14710/ijred.5.3.171-177

  19. Preliminary Results of Subsurface Exploration and Monitoring at the Johnson Creek Landslide, Lincoln County, Oregon

    Science.gov (United States)

    Schulz, William H.; Ellis, William L.

    2007-01-01

    The Johnson Creek landslide is a translational, primarily bedrock landslide located along the Oregon coast about 5 km north of Newport. The landslide has damaged U.S. Highway 101 many times since construction of the highway and at least two geological and geotechnical investigations of the landslide have been performed by Oregon State agencies. In cooperation with the Oregon Department of Geology and Mineral Industries and the Oregon Department of Transportation, the U.S. Geological Survey upgraded landslide monitoring systems and installed additional monitoring devices at the landslide beginning in 2004. Monitoring devices at the landslide measured landslide displacement, rainfall, air temperature, shallow soil-water content, and ground-water temperature and pressure. The devices were connected to automatic dataloggers and read at one-hour and, more recently, 15-minute intervals. Monitoring results were periodically downloaded from the dataloggers using cellular telemetry. The purposes of this report are to describe and present preliminary monitoring data from November 19, 2004, to March 31, 2007.

  20. Continuous ‘Passive’ flow-proportional monitoring of drainage using a new modified Sutro weir (MSW) unit

    DEFF Research Database (Denmark)

    Vendelboe, Anders Lindblad; Rozemeijer, Joachim; de Jonge, Lis Wollesen;

    2016-01-01

    In view of their crucial role in water and solute transport, enhanced monitoring of agricultural subsurface drain tile systems is important for adequate water quality management. However, existing monitoring techniques for flow and contaminant loads from tile drains are expensive and labour...... information for the selection and evaluation of mitigation options to improve water quality.Results from this type of monitoring can provide data for the evaluation and optimisation of best management practices in agriculture in order to produce the highest yield without water quality and recipient surface...... intensive. The aim of this study was to develop a cost-effective and simple method for monitoring loads from tile drains. The Flowcap is a modified Sutro weir (MSW) unit that canbe attached to the outlet of tile drains. It is capable of registering total flow, contaminant loads and flowaveraged...

  1. A mobile laboratory for surface and subsurface imaging in geo-hazard monitoring activity

    Science.gov (United States)

    Cornacchia, Carmela; Bavusi, Massimo; Loperte, Antonio; Pergola, Nicola; Pignatti, Stefano; Ponzo, Felice; Lapenna, Vincenzo

    2010-05-01

    A new research infrastructure for supporting ground-based remote sensing observations in the different phases of georisk management cycle is presented. This instrumental facility has been designed and realised by TeRN, a public-private consortium on Earth Observations and Natural Risks, in the frame of the project "ImpresAmbiente" funded by Italian Ministry of Research and University. The new infrastructure is equipped with ground-based sensors (hyperspectral cameras, thermal cameras, laser scanning and electromagnetic antennae) able to remotely map physical parameters and/or earth-surface properties (temperature, soil moisture, land cover, etc…) and to illuminate near-surface geological structures (fault, groundwater tables, landslide bodies etc...). Furthermore, the system can be used for non-invasive investigations of architectonic buildings and civil infrastructures (bridges, tunnel, road pavements, etc...) interested by natural and man-made hazards. The hyperspectral cameras can acquire high resolution images of earth-surface and cultural objects. They are operating in the Visible Near InfraRed (0.4÷1.0μm) with 1600 spatial pixel and 3.7nm of spectral sampling and in the Short Wave InfraRed (1.3÷2.5µm) spectral region with 320 spatial pixel and 5nm of spectral sampling. The IR cameras are operating in the Medium Wavelength InfraRed (3÷5µm; 640x512; NETDtechniques. The Laser Scanner is characterized by very high data acquisition repetition rate up to 500.000 pxl/sec with a range resolution of 0.1 mm, vertical and horizontal FoV of 310° and 360° respectively with a resolution of 0.0018°. The system is also equipped with a metric camera allows to georeference the high resolution images acquired. The electromagnetic sensors allow to obtain in near real time high-resolution 2D and 3D subsurface tomographic images. The main components are a fully automatic resistivity meter for DC electrical surveys (resistivity) and Induced Polarization, a Ground

  2. Subsurface monitoring of reservoir pressure, temperature, relative humidity, and water content at the CAES Field Experiment, Pittsfield, Illinois: system design

    Energy Technology Data Exchange (ETDEWEB)

    Hostetler, D.D.; Childs, S.W.; Phillips, S.J.

    1983-03-01

    This subsurface-instrumentation design has been developed for the first Compressed Air Energy Storage (CAES) field experiment to be performed in porous media. Energy storage will be accomplished by alternating the injection and withdrawal of compressed air in a confined sandstone aquifer near Pittsfield, Illinois. The overall experiment objective is to characterize the reservoir's geochemical and thermohydraulic response to imposed CAES conditions. Specific experiment objectives require monitoring: air-bubble development; thermal development; cyclic pressure response; reservoir dehydration; and water coning. Supporting these objectives, four parameters will be continuously monitored at depth in the reservoir. They are: temperature; pressure; pore-air relative humidity; and pore-water content. Reservoir temperatures and pressures will range to maximum values approaching 200/sup 0/C and 300 psi, respectively. Both pore-air relative humidity and pore-water content will range from approx. 0 to 100%. This report discusses: instrumentation design; sensor and sensor system calibration; field installation and testing; and instrument-system operation. No comprehensive off-the-shelf instrument package exists to adequately monitor CAES reservoir parameters at depth. The best available sensors were selected and adapted for use under expected ranges of reservoir conditions. The instrumentation design criteria required: suitable sensor accuracy; continuous monitoring capability; redundancy; maximum sensor integrity; contingency planning; and minimum cost-information ratio. Three wells will be instrumented: the injection/withdrawal (I/W) well and the two instrument wells. Sensors will be deployed by wireline suspension in both open and backfilled (with sand) wellbores. The sensors deployed in the I/W well will be retrievable; the instrument-well sensors will not.

  3. Enhanced long-term organics and nitrogen removal and associated microbial community in intermittently aerated subsurface flow constructed wetlands.

    Science.gov (United States)

    Fan, Jinlin; Zhang, Jian; Guo, Wenshan; Liang, Shuang; Wu, Haiming

    2016-08-01

    The long-term enhanced removal efficiency of organics and nitrogen in subsurface flow constructed wetlands (SSF CWs) with and without intermittent aeration for decentralized domestic wastewater was evaluated, and the function of intermittent aeration on microbial community was also investigated in this study. The high and long-term 95.6% COD, 96.1% NH4(+)-N and 85.8% TN removal efficiencies were achieved in experimental intermittently aerated SSF CW compared with non-aerated SSF CW. Aerated SSF CWs also exhibited the excellent removal performance when comparatively comparing with other strategies and techniques applied in CWs. In addition, fluorescence in situ hybridization (FISH) analysis revealed that associated microbial abundance significantly increased owing to intermittent aeration. These results indicated intermittent aeration CWs might be an effective and sustainable strategy for wastewater treatment in rural areas, but require further full-scale investigation in future.

  4. Treatment of high-strength wastewater in tropical constructed wetlands planted with Sesbania sesban: Horizontal subsurface flow versus vertical downflow

    DEFF Research Database (Denmark)

    Dan, Truong Hoang; Quang, Le Nhat; Chiem, Nguyen Huu;

    2011-01-01

    controls. Direct plant uptake constituted only up to 8% of the total-N removal and 2% of the P removal at the lowest loading rate, and was quantitatively of low importance compared to other removal processes. The significant effects of plants were therefore related more to their indirect effects...... subsurface flow system and a saturated vertical downflow system was established with planted and unplanted beds to assess the effects of system design and presence of plants on treatment performance. The systems were loaded with a mixture of domestic and pig farm wastewater at three hydraulic loading rates...... of 80, 160 and 320mmd-1. The S. sesban plants grew very well in the constructed wetland systems and produced 17.2-20.2kgdry matterm-2year-1 with a high nitrogen content. Mass removal rates and removal rate constants increased with loading rate, but at 320mmd-1 the effluent quality was unacceptable...

  5. Nitrogen removal in wood chip combined substrate baffled subsurface-flow constructed wetlands: impact of matrix arrangement and intermittent aeration.

    Science.gov (United States)

    Li, Huai; Chi, Zifang; Yan, Baixing; Cheng, Long; Li, Jianzheng

    2017-02-01

    In this study, two lab-scale baffled subsurface-flow constructed wetlands (BSFCWs), including gravel-wood chips-slag and gravel-slag-wood chips, were operated at different intermittent aeration to evaluate the effect of artificial aeration and slow-released carbon source on the treatment efficiency of high-strength nitrogen wastewater. Results indicated that gravel-slag-wood chips extended aerobic/anaerobic alternating environment to gravel and slag zones and maintained anaerobic condition in the subsequent wood chip section. The order of gravel-slag-wood chip was more beneficial to pollutant removal. Sufficient carbon source supply resulted from wood-chip-framework substrate simultaneously obtained high removals of COD (97%), NH4(+)-N (95%), and TN (94%) in BSFCWs at 2 h aeration per day. The results suggest that intermittent aeration combined with wood chips could achieve high nitrogen removal in BSFCWs.

  6. Sparse calibration of subsurface flow models using nonlinear orthogonal matching pursuit and an iterative stochastic ensemble method

    KAUST Repository

    Elsheikh, Ahmed H.

    2013-06-01

    We introduce a nonlinear orthogonal matching pursuit (NOMP) for sparse calibration of subsurface flow models. Sparse calibration is a challenging problem as the unknowns are both the non-zero components of the solution and their associated weights. NOMP is a greedy algorithm that discovers at each iteration the most correlated basis function with the residual from a large pool of basis functions. The discovered basis (aka support) is augmented across the nonlinear iterations. Once a set of basis functions are selected, the solution is obtained by applying Tikhonov regularization. The proposed algorithm relies on stochastically approximated gradient using an iterative stochastic ensemble method (ISEM). In the current study, the search space is parameterized using an overcomplete dictionary of basis functions built using the K-SVD algorithm. The proposed algorithm is the first ensemble based algorithm that tackels the sparse nonlinear parameter estimation problem. © 2013 Elsevier Ltd.

  7. Advantages of using subsurface flow constructed wetlands for wastewater treatment in space applications: Ground-based mars base prototype

    Science.gov (United States)

    Nelson, M.; Alling, A.; Dempster, W. F.; van Thillo, M.; Allen, John

    Research and design of subsurface flow wetland wastewater treatment systems for a ground-based experimental prototype Mars Base facility has been carried out, using a subsurface flow approach. These systems have distinct advantages in planetary exploration scenarios: they are odorless, relatively low-labor and low-energy, assist in purification of water and recycling of atmospheric CO2, and will support some food crops. An area of 6-8 m2 may be sufficient for integration of wetland wastewater treatment with a prototype Mars Base supporting 4-5 people. Discharge water from the wetland system will be used as irrigation water for the agricultural crop area, thus ensuring complete recycling and utilization of nutrients. Since the primary requirements for wetland treatment systems are warm temperatures and lighting, such bioregenerative systems may be integrated into early Mars base habitats, since waste heat from the lights may be used for temperature maintenance in the human living environment. "Wastewater gardens ™" can be modified for space habitats to lower space and mass requirements. Many of its construction requirements can eventually be met with use of in-situ materials, such as gravel from the Mars surface. Because the technology requires little machinery and no chemicals, and relies more on natural ecological mechanisms (microbial and plant metabolism), maintenance requirements are minimized, and systems can be expected to have long operating lifetimes. Research needs include suitability of Martian soil and gravel for wetland systems, system sealing and liner options in a Mars Base, and wetland water quality efficiency under varying temperature and light regimes.

  8. COD, nutrient removal and disinfection efficiency of a combined subsurface and surface flow constructed wetland: A case study.

    Science.gov (United States)

    Sartori, Laura; Canobbio, Sergio; Fornaroli, Riccardo; Cabrini, Riccardo; Marazzi, Francesca; Mezzanotte, Valeria

    2016-01-01

    A constructed wetland system composed of a subsurface flow wetland, a surface flow wetland and a facultative pond was studied from July 2008 until May 2012. It was created to treat the domestic sewage produced by a hamlet of 150 inhabitants. Monthly physicochemical and microbiological analyses were carried out in order to evaluate the removal efficiency of each stage of the process and of the total treatment system. Pair-wise Student's t-tests showed that the mean removal of each considered parameter was significantly different (α = 0.05) between the various treatment phases. Two-way ANOVA and Tukey's HSD tests were used to find significant differences between wetland types and seasons in the removal efficiency of the considered water quality parameters. Significant differences in percent removal efficiency between the treatment phases were observed for total phosphorus, total nitrogen, ammonia nitrogen and organic load (expressed as Chemical Oxygen Demand). In general, the wastewater treatment was carried by the sub-superficial flow phase mainly, both in growing season and in quiescence season. Escherichia coli removal ranged from 98% in quiescence season to >99% in growing season (approximately 2-3 orders of magnitude). The inactivation of fecal bacteria was not influenced by the season, but only by the treatment phase.

  9. Clogging development and hydraulic performance of the horizontal subsurface flow stormwater constructed wetlands: a laboratory study.

    Science.gov (United States)

    Tang, Ping; Yu, Bohai; Zhou, Yongchao; Zhang, Yiping; Li, Jin

    2017-04-01

    The horizontal subsurface constructed wetland (HSSF CW) is a highly effective technique for stormwater treatment. However, progressive clogging in HSSF CW is a widespread operational problem. The aim of this study was to understand the clogging development of HSSF CWs during stormwater treatment and to assess the influence of microorganisms and vegetation on the clogging. Moreover, the hydraulic performance of HSSF CWs in the process of clogging was evaluated in a tracer experiment. The results show that the HSSF CW can be divided into two sections, section I (circa 0-35 cm) and section II (circa 35-110 cm). The clogging is induced primarily by solid entrapment in section I and development of biofilm and vegetation roots in section II, respectively. The influence of vegetation and microorganisms on the clogging appears to differ in sections I and II. The tracer experiment shows that the hydraulic efficiency (λ) and the mean hydraulic retention time (t mean) increase with the clogging development; although, the short-circuiting region (S) extends slightly. In addition, the presence of vegetation can influence the hydraulic performance of the CWs, and their impact depends on the characteristics of the roots.

  10. Hydrologic and biogeochemical controls of river subsurface solutes under agriculturally enhanced ground water flow

    Science.gov (United States)

    Wildman, R.A.; Domagalski, J.L.; Hering, J.G.

    2009-01-01

    The relative influences of hydrologic processes and biogeochemistry on the transport and retention of minor solutes were compared in the riverbed of the lower Merced River (California, USA). The subsurface of this reach receives ground water discharge and surface water infiltration due to an altered hydraulic setting resulting from agricultural irrigation. Filtered ground water samples were collected from 30 drive point locations in March, June, and October 2004. Hydrologic processes, described previously, were verified by observations of bromine concentrations; manganese was used to indicate redox conditions. The separate responses of the minor solutes strontium, barium, uranium, and phosphorus to these influences were examined. Correlation and principal component analyses indicate that hydrologic processes dominate the distribution of trace elements in the ground water. Redox conditions appear to be independent of hydrologic processes and account for most of the remaining data variability. With some variability, major processes are consistent in two sampling transects separated by 100 m. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  11. Uncertainty analyses of infiltration and subsurface flow and transport for SDMP sites

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, P.D.; Rockhold, M.L.; Gee, G.W. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-09-01

    US Nuclear Regulatory Commission staff have identified a number of sites requiring special attention in the decommissioning process because of elevated levels of radioactive contaminants. Traits common to many of these sites include limited data characterizing the subsurface, the presence of long-lived radionuclides necessitating a long-term analysis (1,000 years or more), and potential exposure through multiple pathways. As a consequence of these traits, the uncertainty in predicted exposures can be significant. In addition, simplifications to the physical system and the transport mechanisms are often necessary to reduce the computational requirements of the analysis. Several multiple-pathway transport codes exist for estimating dose, two of which were used in this study. These two codes have built-in Monte Carlo simulation capabilities that were used for the uncertainty analysis. Several tools for improving uncertainty analyses of exposure estimates through the groundwater pathway have been developed and are discussed in this report. Generic probability distributions for unsaturated and saturated zone soil hydraulic parameters are presented. A method is presented to combine the generic distributions with site-specific water retention data using a Bayesian analysis. The resulting updated soil hydraulic parameter distributions can be used to obtain an updated estimate of the probability distribution of dose. The method is illustrated using a hypothetical decommissioning site.

  12. Borehole Calibration Facilities to Support Gamma Logging for Hanford Subsurface Investigation and Contaminant Monitoring - 13516

    Energy Technology Data Exchange (ETDEWEB)

    McCain, R.G.; Henwood, P.D.; Pope, A.D.; Pearson, A.W. [S M Stoller Corporation, 2439 Robertson Drive, Richland, WA 99354 (United States)

    2013-07-01

    Repeated gamma logging in cased holes represents a cost-effective means to monitor gamma-emitting contamination in the deep vadose zone over time. Careful calibration and standardization of gamma log results are required to track changes and to compare results over time from different detectors and logging systems. This paper provides a summary description of Hanford facilities currently available for calibration of logging equipment. Ideally, all logging organizations conducting borehole gamma measurements at the Hanford Site will take advantage of these facilities to produce standardized and comparable results. (authors)

  13. Subsurface Monitor for Dissolved Inorganic Carbon at Geological Sequestration Site Phase 1 SBIR Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sheng Wu

    2012-08-03

    Phase I research of this SBIR contract has yielded anticipated results and enable us to develop a practical new instrument to measure the Dissolved Inorganic Carbons (DIC) as well as Supercritical (SC) CO2 in underground brine water at higher sensitivity, lower cost, higher frequency and longer period of time for the Monitoring, Verification & Accounting (MVA) of CO2 sequestration as well as Enhanced Oil Recovery (EOR). We show that reduced cost and improved performance are possible; both future and emerging market exist for the proposed new instrument.

  14. A modular subsurface borehole-tower for deep vadose zone monitoring

    Science.gov (United States)

    Breitenstein, Daniel; Or, Dani

    2016-04-01

    Some of the most urgent contemporary societal challenges ranging from climate change to ecosystem services and food security are strongly linked to processes taking place in the vadose zone. The growing interest in this critical zone prompted a massive deployment of eco-hydrological networks (TERENO, CZO, and more) focusing on long term and highly resolved monitoring of key variables such as soil moisture, pressure, temperature, gas fluxes and more. A challenge in all these endeavors remains the reliable and consistent acquisition of variables to depths of eco-hydrological interest (a few meters in some cases), especially soil moisture. In the absence of off-the-shelf sensor systems capable of vertically resolved acquisition of these variables, we developed a prototype of a modular borehole-based tower for simultaneous monitoring of water content, temperature, oxygen and CO2 gas concentrations, and potentially other variables (relative humidity, capillary pressure). The modular tower is made up of 1.5 m sections of 75 mm PVC tubing with TDR waveguides mounted on outer walls. Each paired waveguides (0.15 m in length) were installed on two opposing sides of inflatable sections along the modular unit to ensure contact with the borehole walls. Oxygen and CO2 are measured using solid-state and optical gas sensors that could be periodically calibrated for potential drift. A prototype that could be extended to 6 m depth and preliminary calibration results will be presented (as a potential design for future CZO's). We welcome suggestions for expansion and improvements.

  15. Seasonal ERT monitoring of subsurface processes connected to freezing, thawing, snow accumulation and melt cycles

    Science.gov (United States)

    Krzeminska, Dominika; Starkloff, Torsten; Bloem, Esther; Stolte, Jannes

    2016-04-01

    For a better understanding of processes that influence snowmelt infiltration and runoff, and their consequences on soil erosion during spring periods, we established a long-term winter-spring ERT transect in the Gryteland catchment (Norway). The ERT transect is 71 m long, with 1 m spacing between the electrodes. It covers a depression with a north and south facing slope. The readings are collected once a week and, if needed, after a sudden change in weather conditions. Additionally, the soil transect is equipped with six TDR profiles, which register soil moisture and soil temperature every thirty minutes, at five depths (5, 10, 20, 30, 40 cm), for quantifying the ERT readings. The measurements performed during winter 2014/2015 gave promising results and showed the potential of ERT monitoring for understanding the soil thermal and hydraulic processes occurring during a winter and early spring. Moreover, there are visible differences in temporal trends and spatial variations in observed ERT patterns on the opposite facing slopes, which are of special interest. With the on-going experiment, we are aiming to understand the reoccurrence of the observed processes as well as to quantify soil moisture patterns. Herein, we would like to present the preliminary result of two ERT experiments (2014/2015 and 2015/2016) and discuss the advantages and limitations of our experiments. Moreover, we would like to stimulate the discussion about the potential of ERT for spatial and temporal monitoring of soil hydraulic and thermal processes and indirect measurements of soil water content.

  16. Sub-surface Meridional Flow Results from MWO, GONG, and MDI during Solar Cycle 23

    Science.gov (United States)

    Pinkerton, Stephen; Rhodes, Edward J.; Bogart, Richard S.

    2014-06-01

    Time series of full-disk Dopplergrams were acquired at the 60-Foot Solar tower of the Mount Wilson Observatory every year between 1987 and 2009. Analysis of this archive revealed that the focal plane of the Tower did experience a small amount of systematic rotation, which suggested that the alignment of the optics had changed slightly over the years since its construction in 1907. This has caused some of the initial daily flow maps to possess a so-called “washing machine” effect similar to the pattern that was seen in raw GONG flow maps. We have incorporated a systematic program of ring-diagram analysis in which we have tracked the raw solar images using five differing assumed instrumental rotation rates. We have then gone on to compute synoptic maps of the horizontal flow vectors at several different depths over much of Solar Cycle 23 in order to study how such an instrumental rotation might affect both the zonal and meridional flows as functions of latitude, depth, and time. We compare these results with GONG and MDI flow measurements to empirically determine the regime within which the MWO results are reliable and extend our analysis into Solar Cycle 22.

  17. Wireless Subsurface Microsensors for Health Monitoring of Thermal Protection Systems on Hypersonic Vehicles

    Science.gov (United States)

    Milos, Frank S.; Watters, David G.; Pallix, Joan B.; Bahr, Alfred J.; Huestis, David L.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles in order to reduce life cycle costs, to increase safety margins, and to improve mission reliability. NASA Ames is leading the effort to develop inspection and health management technologies for thermal protection systems. This paper summarizes a joint project between NASA Ames and SRI International to develop 'SensorTags,' radio frequency identification devices coupled with event-recording sensors, that can be embedded in the thermal protection system to monitor temperature or other quantities of interest. Two prototype SensorTag designs containing thermal fuses to indicate a temperature overlimit are presented and discussed.

  18. Smart Sensing Strip Using Monolithically Integrated Flexible Flow Sensor for Noninvasively Monitoring Respiratory Flow.

    Science.gov (United States)

    Jiang, Peng; Zhao, Shuai; Zhu, Rong

    2015-12-15

    This paper presents a smart sensing strip for noninvasively monitoring respiratory flow in real time. The monitoring system comprises a monolithically-integrated flexible hot-film flow sensor adhered on a molded flexible silicone case, where a miniaturized conditioning circuit with a Bluetooth4.0 LE module are packaged, and a personal mobile device that wirelessly acquires respiratory data transmitted from the flow sensor, executes extraction of vital signs, and performs medical diagnosis. The system serves as a wearable device to monitor comprehensive respiratory flow while avoiding use of uncomfortable nasal cannula. The respiratory sensor is a flexible flow sensor monolithically integrating four elements of a Wheatstone bridge on single chip, including a hot-film resistor, a temperature-compensating resistor, and two balancing resistors. The monitor takes merits of small size, light weight, easy operation, and low power consumption. Experiments were conducted to verify the feasibility and effectiveness of monitoring and diagnosing respiratory diseases using the proposed system.

  19. Acoustic module of the Acquabona (Italy debris flow monitoring system

    Directory of Open Access Journals (Sweden)

    A. Galgaro

    2005-01-01

    Full Text Available Monitoring of debris flows aimed to the assessment of their physical parameters is very important both for theoretical and practical purposes. Peak discharge and total volume of debris flows are crucial for designing effective countermeasures in many populated mountain areas where losses of lives and property damage could be avoided. This study quantifies the relationship between flow depth, acoustic amplitude of debris flow induced ground vibrations and front velocity in the experimental catchment of Acquabona, Eastern Dolomites, Italy. The analysis of data brought about the results described in the following. Debris flow depth and amplitude of the flow-induced ground vibrations show a good positive correlation. Estimation of both mean front velocity and peak discharge can be simply obtained monitoring the ground vibrations, through geophones installed close to the flow channel; the total volume of debris flow can be so directly estimated from the integral of the ground vibrations using a regression line. The application of acoustic technique to debris flow monitoring seems to be of the outmost relevance in risk reduction policies and in the correct management of the territory. Moreover this estimation is possible in other catchments producing debris flows of similar characteristics by means of their acoustic characterisation through quick and simple field tests (Standard Penetration Tests and seismic refraction surveys.

  20. Development of Radon-222 as Natural Tracer for Monitoring the Remediation of NAPL in the Subsurface

    Energy Technology Data Exchange (ETDEWEB)

    Brian M. Davis; Lewis Semprini; Jonathan Istok

    2003-02-27

    Naturally occurring 222-radon in ground water can potentially be used as an in situ partitioning tracer to characterize dense nonaqueous phase liquid (DNAPL) saturations. The static method involves comparing radon concentrations in water samples from DNAPL-contaminated and non-contaminated portions of an aquifer. During a push-pull test, a known volume of test solution (radon-free water containing a conservation tracer) is first injected (''pushed'') into a well; flow is then reversed and the test solution/groundwater mixture is extracted (''pulled'') from the same well. In the presence of NAPL radon transport is retarded relative to the conservative tracer. Assuming linear equilibrium partitioning, retardation factors for radon can be used to estimate NAPL saturations.The utility of this methodology was evaluated in laboratory and field settings.

  1. Parameterization of Finite-Element Cryo-Hydrologic Sand Dune Model to Constrain Debris-Flow-Initiating Subsurface Temperatures and Pore-Water Pressures, Great Kobuk Sand Dunes, Alaska

    Science.gov (United States)

    Dinwiddie, C. L.; Hooper, D. M.

    2015-05-01

    To explain how debris flows form at subfreezing air temperatures, we present meteorology-driven, numerical simulation-derived subsurface temperature and pore-water pressure profiles in the Great Kobuk Sand Dunes of Alaska, for incipient flow events.

  2. New argon-argon (40Ar/39Ar) radiometric age dates from selected subsurface basalt flows at the Idaho National Laboratory, Idaho

    Science.gov (United States)

    Hodges, Mary K.; Turrin, Brent D.; Champion, Duane E.; Swisher, Carl C.

    2015-01-01

    In 2011, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collected samples for 12 new argon-argon radiometric ages from eastern Snake River Plain olivine tholeiite basalt flows in the subsurface at the Idaho National Laboratory. The core samples were collected from flows that had previously published paleomagnetic data. Samples were sent to Rutgers University for argon-argon radiometric dating analyses.

  3. Flow Monitoring Experiences at the Ethernet-Layer

    NARCIS (Netherlands)

    Hofstede, Rick; Drago, Idilio; Sperotto, Anna; Pras, Aiko; Lehnert, Ralf

    2011-01-01

    Flow monitoring is a scalable technology for providing summaries of network activity. Being deployed at the IP-layer, it uses fixed flow definitions, based on fields of the IP-layer and higher layers. Since several backbone network operators are considering the deployment of (Carrier) Ethernet in th

  4. Do asthma patients prefer to monitor symptoms or peak flow?

    Science.gov (United States)

    Harver, Andrew; Humphries, C Thomas; Kotses, Harry

    2009-11-01

    We administered a 65-item survey to patients to assess preference of symptoms and peak flow to detect worsening asthma and to collect information about asthma triggers, asthma knowledge sources, and barriers to peak flow meter use. It was completed by 139 asthma patients. Survey responses were comparable for adult and pediatric patients and for those who owned peak flow meters and those who did not. But patients who owned a peak flow meter reported more severe asthma than others. On average, the patients preferred symptoms to peak flow for assessing worsening asthma. It is likely that the preference for symptom over peak flow monitoring was effort related: Patients preferred symptom monitoring because it was the easier of the two to conduct.

  5. Hot-wire amperometric monitoring of flowing streams.

    Science.gov (United States)

    Wang, J; Jasinski, M; Flechsig, G U; Grundler, P; Tian, B

    2000-01-10

    This paper describes the design of a hot-wire electrochemical flow detector, and the advantages accrued from the effects of locally increased temperature, mainly thermally induced convection, upon the amperometric monitoring of flowing streams. A new hydrodynamic modulation voltammetric approach is presented, in which the solution flow rate remains constant while the temperature of the working electrode is modulated. Factors influencing the response, including the flow rate, temperature pulse, or applied potential, have been investigated. The hot-wire operation results also in a significant enhancement of the flow injection amperometric response. The minimal flow rate dependence observed with the heated electrode should benefit the on-line monitoring of streams with fluctuated natural convection, as well as various in-situ remote sensing applications.

  6. Enhancement of azo dye Acid Orange 7 removal in newly developed horizontal subsurface-flow constructed wetland.

    Science.gov (United States)

    Tee, Heng-Chong; Lim, Poh-Eng; Seng, Chye-Eng; Mohd Nawi, Mohd Asri; Adnan, Rohana

    2015-01-01

    Horizontal subsurface-flow (HSF) constructed wetland incorporating baffles was developed to facilitate upflow and downflow conditions so that the treatment of pollutants could be achieved under multiple aerobic, anoxic and anaerobic conditions sequentially in the same wetland bed. The performances of the baffled and conventional HSF constructed wetlands, planted and unplanted, in the removal of azo dye Acid Orange 7 (AO7) were compared at the hydraulic retention times (HRT) of 5, 3 and 2 days when treating domestic wastewater spiked with AO7 concentration of 300 mg/L. The planted baffled unit was found to achieve 100%, 83% and 69% AO7 removal against 73%, 46% and 30% for the conventional unit at HRT of 5, 3 and 2 days, respectively. Longer flow path provided by baffled wetland units allowed more contact of the wastewater with the rhizomes, microbes and micro-aerobic zones resulting in relatively higher oxidation reduction potential (ORP) and enhanced performance as kinetic studies revealed faster AO7 biodegradation rate under aerobic condition. In addition, complete mineralization of AO7 was achieved in planted baffled wetland unit due to the availability of a combination of aerobic, anoxic and anaerobic conditions.

  7. Evaluation of clogging in planted and unplanted horizontal subsurface flow constructed wetlands: solids accumulation and hydraulic conductivity reduction.

    Science.gov (United States)

    De Paoli, André Cordeiro; von Sperling, Marcos

    2013-01-01

    This study aimed to evaluate the behaviour of two horizontal subsurface flow constructed wetland units regarding solids build up and clogging of the filter medium. In order to analyse the causes of this process, which is considered the major operational problem of constructed wetlands, studies were carried out to characterize accumulated solids and hydraulic conductivity at specific points of the beds of two wetlands (planted with Typha latifolia and unplanted units) receiving effluent from an upflow anaerobic sludge blanket reactor treating sanitary sewage (population equivalent of 50 inhabitants each unit). The experiments were performed after the units were operating for 2 years and 4 months. This study presents comparative results related to the quantification and characterization of accumulated solids and hydraulic conductivity along the length and width of the filter beds. Approximately 80% of the solids found were inorganic (fixed). Near the inlet end, the rate interstitial solids/attached solids was 5.0, while in the outlet end it was reduced to 1.5. Hydraulic conductivity was lower near the inlet of the units (as expected) and, by comparing the planted wetland with the unplanted, the hydraulic conductivity was lower in the former, resulting in larger undesired surface flow.

  8. Enhancing the removal of arsenic, boron and heavy metals in subsurface flow constructed wetlands using different supporting media.

    Science.gov (United States)

    Allende, K Lizama; Fletcher, T D; Sun, G

    2011-01-01

    The presence of arsenic and heavy metals in drinking water sources poses a serious health risk due to chronic toxicological effects. Constructed wetlands have the potential to remove arsenic and heavy metals, but little is known about pollutant removal efficiency and reliability of wetlands for this task. This lab-scale study investigated the use of vertical subsurface flow constructed wetlands for removing arsenic, boron, copper, zinc, iron and manganese from synthetic wastewater. Gravel, limestone, zeolite and cocopeat were employed as wetland media. Conventional gravel media only showed limited capability in removing arsenic, iron, copper and zinc; and it showed virtually no capability in removing manganese and boron. In contrast, alternative wetland media: cocopeat, zeolite and limestone, demonstrated significant efficiencies--in terms of percentage removal and mass rate per m3 of wetland volume--for removing arsenic, iron, manganese, copper and zinc; their ability to remove boron, in terms of mass removal rate, was also higher than that of the gravel media. The overall results demonstrated the potential of using vertical flow wetlands to remove arsenic and metals from contaminated water, having cocopeat, zeolite or limestone as supporting media.

  9. Systems and Sensors for Debris-flow Monitoring and Warning.

    Science.gov (United States)

    Arattano, Massimo; Marchi, Lorenzo

    2008-04-04

    Debris flows are a type of mass movement that occurs in mountain torrents. They consist of a high concentration of solid material in water that flows as a wave with a steep front. Debris flows can be considered a phenomenon intermediate between landslides and water floods. They are amongst the most hazardous natural processes in mountainous regions and may occur under different climatic conditions. Their destructiveness is due to different factors: their capability of transporting and depositing huge amounts of solid materials, which may also reach large sizes (boulders of several cubic meters are commonly transported by debris flows), their steep fronts, which may reach several meters of height and also their high velocities. The implementation of both structural and nonstructural control measures is often required when debris flows endanger routes, urban areas and other infrastructures. Sensor networks for debris-flow monitoring and warning play an important role amongst non-structural measures intended to reduce debris-flow risk. In particular, debris flow warning systems can be subdivided into two main classes: advance warning and event warning systems. These two classes employ different types of sensors. Advance warning systems are based on monitoring causative hydrometeorological processes (typically rainfall) and aim to issue a warning before a possible debris flow is triggered. Event warning systems are based on detecting debris flows when these processes are in progress. They have a much smaller lead time than advance warning ones but are also less prone to false alarms. Advance warning for debris flows employs sensors and techniques typical of meteorology and hydrology, including measuring rainfall by means of rain gauges and weather radar and monitoring water discharge in headwater streams. Event warning systems use different types of sensors, encompassing ultrasonic or radar gauges, ground vibration sensors, videocameras, avalanche pendulums, photocells

  10. Systems and Sensors for Debris-flow Monitoring and Warning

    Directory of Open Access Journals (Sweden)

    Lorenzo Marchi

    2008-04-01

    Full Text Available Debris flows are a type of mass movement that occurs in mountain torrents. They consist of a high concentration of solid material in water that flows as a wave with a steep front. Debris flows can be considered a phenomenon intermediate between landslides and water floods. They are amongst the most hazardous natural processes in mountainous regions and may occur under different climatic conditions. Their destructiveness is due to different factors: their capability of transporting and depositing huge amounts of solid materials, which may also reach large sizes (boulders of several cubic meters are commonly transported by debris flows, their steep fronts, which may reach several meters of height and also their high velocities. The implementation of both structural and nonstructural control measures is often required when debris flows endanger routes, urban areas and other infrastructures. Sensor networks for debris-flow monitoring and warning play an important role amongst non-structural measures intended to reduce debris-flow risk. In particular, debris flow warning systems can be subdivided into two main classes: advance warning and event warning systems. These two classes employ different types of sensors. Advance warning systems are based on monitoring causative hydrometeorological processes (typically rainfall and aim to issue a warning before a possible debris flow is triggered. Event warning systems are based on detecting debris flows when these processes are in progress. They have a much smaller lead time than advance warning ones but are also less prone to false alarms. Advance warning for debris flows employs sensors and techniques typical of meteorology and hydrology, including measuring rainfall by means of rain gauges and weather radar and monitoring water discharge in headwater streams. Event warning systems use different types of sensors, encompassing ultrasonic or radar gauges, ground vibration sensors, videocameras, avalanche

  11. Wireless Subsurface Sensors for Health Monitoring of Thermal Protection Systems on Hypersonic Vehicles

    Science.gov (United States)

    Milos, Frank S.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles (RLVs) in order to reduce life cycle costs, to increase safety margins, and to improve mission reliability. NASA Ames is leading the effort to develop inspection and health management technologies for thermal protection systems. This paper summarizes a joint project between NASA Ames and industry partners to develop "wireless" devices that can be embedded in the thermal protection system to monitor temperature or other quantities of interest. These devices are sensors integrated with radio-frequency identification (RFID) microchips to enable non-contact communication of sensor data to an external reader that may be a hand-held scanner or a large portal. Both passive and active prototype devices have been developed. The passive device uses a thermal fuse to indicate the occurrence of excessive temperature. This device has a diameter under 0.13 cm. (suitable for placement in gaps between ceramic TPS tiles on an RLV) and can withstand 370 C for 15 minutes. The active device contains a small battery to provide power to a thermocouple for recording a temperature history during flight. The bulk of the device must be placed beneath the TPS for protection from high temperature, but the thermocouple can be placed in a hot location such as near the external surface.

  12. Monitoring Perennial Sub-Surface Waterlogged Croplands Based on MODIS in Jianghan Plain, Middle Reaches of the Yangtze River

    Institute of Scientific and Technical Information of China (English)

    XIAO Fei; LI Yuan-zheng; DU Yun; LING Feng; YAN Yi; FENG Qi; BAN Xuan

    2014-01-01

    Perennial waterlogged soil (PWS) is induced by the high level of groundwater, and has a persistent impact on natural ecosystems and agricultural production. Traditionally, distribution information regarding PWS is mainly collected from in situ measurements through groundwater level surveys and physicochemical property analyses. However, in situ measurements of PWS are costly and time-consuming, only rough estimates of PWS areas are available in some regions. In this paper, we developed a method to monitor the perennial waterlogged cropland using time-series moderate resolution imaging spectroradiometer (MODIS) data. The Jianghan Plain, a lfoodplain located in the middle reaches of the Yangtze River, was selected as the study area. Temporal variations of the enhanced vegetation index (EVI), night land surface temperature (LST), diurnal LST differences (∆LST), albedo, and the apparent thermal inertia (ATI) were used to analyze the ecological and thermodynamic characteristics of the waterlogged croplands. To obtain pure remote sensing signatures of the waterlogged cropland from mixed pixels, the croplands were classiifed into different types according to soil and land cover types in this paper, and a linear mixing model was developed by iftting the signatures using the multiple linear regression approach. Afterwards, another linear spectral mixing model was used to get the proportions of waterlogged croplands in each 1 km×1 km pixel. The result showed an acceptable accuracy with a root-mean-square error of 0.093. As a tentative method, the procedure described in this paper works efifciently as a method to monitor the spatial patterns of perennial sub-surface waterlogged croplands at a wide scale.

  13. A cost-effective and field-ready potentiostat that poises subsurface electrodes to monitor bacterial respiration.

    Science.gov (United States)

    Friedman, Elliot S; Rosenbaum, Miriam A; Lee, Alexander W; Lipson, David A; Land, Bruce R; Angenent, Largus T

    2012-02-15

    Here, we present the proof-of-concept for a subsurface bioelectrochemical system (BES)-based biosensor capable of monitoring microbial respiration that occurs through exocellular electron transfer. This system includes our open-source design of a three-channel microcontroller-unit (MCU)-based potentiostat that is capable of chronoamperometry, which laboratory tests showed to be accurate within 0.95 ± 0.58% (95% Confidence Limit) of a commercial potentiostat. The potentiostat design is freely available online: http://angenent.bee.cornell.edu/potentiostat.html. This robust and field-ready potentiostat, which can withstand temperatures of -30°C, can be manufactured at relatively low cost ($600), thus, allowing for en-masse deployment at field sites. The MCU-based potentiostat was integrated with electrodes and a solar panel-based power system, and deployed as a biosensor to monitor microbial respiration in drained thaw lake basins outside Barrow, AK. At three different depths, the working electrode of a microbial three-electrode system (M3C) was maintained at potentials corresponding to the microbial reduction of iron(III) compounds and humic acids. Thereby, the working electrode mimics these compounds and is used by certain microbes as an electron acceptor. The sensors revealed daily cycles in microbial respiration. In the medium- and deep-depth electrodes the onset of these cycles followed a considerable increase in overall activity that corresponded to those soils reaching temperatures conducive to microbial activity as the summer thaw progressed. The BES biosensor is a valuable tool for studying microbial activity in situ in remote environments, and the cost-efficient design of the potentiostat allows for wide-scale use in remote areas. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Continuous-flow free acid monitoring method and system

    Science.gov (United States)

    Strain, J.E.; Ross, H.H.

    1980-01-11

    A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.

  15. Subsurface Gas Flow and Ice Grain Acceleration within Enceladus and Europa Fissures: 2D DSMC Models

    Science.gov (United States)

    Tucker, O. J.; Combi, M. R.; Tenishev, V.

    2014-12-01

    The ejection of material from geysers is a ubiquitous occurrence on outer solar system bodies. Water vapor plumes have been observed emanating from the southern hemispheres of Enceladus and Europa (Hansen et al. 2011, Roth et al. 2014), and N2plumes carrying ice and ark particles on Triton (Soderblom et al. 2009). The gas and ice grain distributions in the Enceladus plume depend on the subsurface gas properties and the geometry of the fissures e.g., (Schmidt et al. 2008, Ingersoll et al. 2010). Of course the fissures can have complex geometries due to tidal stresses, melting, freezing etc., but directly sampled and inferred gas and grain properties for the plume (source rate, bulk velocity, terminal grain velocity) can be used to provide a basis to constrain characteristic dimensions of vent width and depth. We used a 2-dimensional Direct Simulation Monte Carlo (DSMC) technique to model venting from both axi-symmetric canyons with widths ~2 km and narrow jets with widths ~15-40 m. For all of our vent geometries, considered the water vapor source rates (1027­ - 1028 s-1) and bulk gas velocities (~330 - 670 m/s) obtained at the surface were consistent with inferred values obtained by fits of the data for the plume densities (1026 - 1028 s-1, 250 - 1000 m/s) respectively. However, when using the resulting DSMC gas distribution for the canyon geometries to integrate the trajectories of ice grains we found it insufficient to accelerate submicron ice grains to Enceladus' escape speed. On the other hand, the gas distributions in the jet like vents accelerated grains > 10 μm significantly above Enceladus' escape speed. It has been suggested that micron-sized grains are ejected from the vents with speeds comparable to the Enceladus escape speed. Here we report on these results including comparisons to results obtained from 1D models as well as discuss the implications of our plume model results. We also show preliminary results for similar considerations applied to Europa

  16. Removing heavy metals from Isfahan composting leachate by horizontal subsurface flow constructed wetland.

    Science.gov (United States)

    Bakhshoodeh, Reza; Alavi, Nadali; Soltani Mohammadi, Amir; Ghanavati, Hossein

    2016-06-01

    Composting facility leachate usually contains high concentrations of pollutants including heavy metals that are seriously harmful to the environment and public health. The main purpose of this study was to evaluate heavy metals removal from Isfahan composting facility (ICF) leachate by a horizontal flow constructed wetland (HFCWs) system. Two horizontal systems were constructed, one planted with vetiver and the other without plant as a control. They both operated at a flow rate of 24 L/day with a 5-day hydraulic retention time (HRT). The average removal efficiencies for Cr (53 %), Cd (40 %), Ni (35 %), Pb (30 %), Zn (35 %), and Cu (40 %) in vetiver constructed wetland were significantly higher than those of the control (P Vetiver tolerates the extreme condition in leachate including high total dissolved solids.

  17. Sequential Nitrification/Denitrification in Subsurface Flow Constructed Wetlands. A Literature Review

    Science.gov (United States)

    1992-12-01

    2/d3o e ia cordata 12.5 Common cattail 4.4 Common arrowhead 8.3 Canna flacida 7.9 .Si•l•us.ung•en 3.4 Scru validus 7.3 I Reed (1992) by doing an...Aeration And Preferential Flow Studied Using Bromide And Dye Tracers. Wat. Res. 21:591-599. Breen, P.F. 1990. A Mass Balance Method For Assessing The

  18. Determination of the hydraulic residence time of two subsurface-flow constructed wetlands using radiotracers

    Energy Technology Data Exchange (ETDEWEB)

    Debien, Bruno R., E-mail: brunordebien@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept de Geografia. Lab. de Geomorfologia; Barreto, Alberto A.; Pinto, Amenonia M.F.; Moreira, Rubens M., E-mail: aab@cdtn.br, E-mail: amfp@cdtn.br, E-mail: rubens@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    The adoption of constructed wetland systems (CW's) with subsuperficial drainage for sewage treatment is increasingly growing in places with low technological resources and available land. The efficient removal of pollutants depends on the internal flow characteristics in the CW and on its hydraulic residence time (HRT). In the present work {sup 82}Br - a gamma radiation emitter, produced from soluble potassium bromide irradiated in the TRIGA reactor at the Centre for the Development of Nuclear Energy (CDTN) - was used as a pseudo-conservative tracer for the comparative study of aqueous phase flow dynamics in two CW's: one in which plants were grown (WP) whereas the other had no plants (WNP). Experimental hydraulic residence time values were found to be very close to the theoretical one, while dispersion numbers obtained for both CW's were quite small. Besides these measured hydrodynamic parameters, the residence time distribution (RTD) curves of the tracer test and the results of modeling of experimental data also demonstrate the tendency of the units to display a plug flow-like effluent hydraulic transport within their systems, as expected from their designs, considering the large length/width ratio (L/W=8). (author)

  19. Calculating e-flow using UAV and ground monitoring

    Science.gov (United States)

    Zhao, C. S.; Zhang, C. B.; Yang, S. T.; Liu, C. M.; Xiang, H.; Sun, Y.; Yang, Z. Y.; Zhang, Y.; Yu, X. Y.; Shao, N. F.; Yu, Q.

    2017-09-01

    Intense human activity has led to serious degradation of basin water ecosystems and severe reduction in the river flow available for aquatic biota. As an important water ecosystem index, environmental flows (e-flows) are crucial for maintaining sustainability. However, most e-flow measurement methods involve long cycles, low efficiency, and transdisciplinary expertise. This makes it impossible to rapidly assess river e-flows at basin or larger scales. This study presents a new method to rapidly assessing e-flows coupling UAV and ground monitorings. UAV was firstly used to calculate river-course cross-sections with high-resolution stereoscopic images. A dominance index was then used to identify key fish species. Afterwards a habitat suitability index, along with biodiversity and integrity indices, was used to determine an appropriate flow velocity with full consideration of the fish spawning period. The cross-sections and flow velocity values were then combined into AEHRA, an e-flow assessment method for studying e-flows and supplying-rate. To verify the results from this new method, the widely used Tennant method was employed. The root-mean-square errors of river cross-sections determined by UAV are less than 0.25 m, which constitutes 3-5% water-depth of the river cross-sections. In the study area of Jinan city, the ecological flow velocity (VE) is equal to or greater than 0.11 m/s, and the ecological water depth (HE) is greater than 0.8 m. The river ecosystem is healthy with the minimum e-flow requirements being always met when it is close to large rivers, which is beneficial for the sustainable development of the water ecosystem. In the south river channel of Jinan, the upstream flow mostly meets the minimum e-flow requirements, and the downstream flow always meets the minimum e-flow requirements. The north of Jinan consists predominantly of artificial river channels used for irrigation. Rainfall rarely meets the minimum e-flow and irrigation water requirements

  20. Detection of Subsurface Supergranulation Structure and Flows from MDI High-Resolution Data using Time-Distance Techniques

    Science.gov (United States)

    Duvall, T. L., Jr.; Kosovichev, A. G.; Scherrer, P. H.; Milford, P. N.

    1996-05-01

    The supergranulation is seen at the surface of the sun in the doppler shift of spectrum lines as an apparent cellular convection pattern with a scale of about 4% of the solar radius. This scale is about 30 times larger than the granulation, seen in white light. Why these distinct scales would be present (and possibly a third intermediate scale mesogranulation) is somewhat of a mystery. Also unknown is the depth structure of the convection. We have used acoustic wave measurements from the MDI experiment on SOHO to address these questions. By crosscorrelating the signal at one location with that on annuli centered on the location, it is possible to measure times for waves to travel over known subsurface ray paths. With some variations on this theme, it is possible to measure horizontal and vertical flows and sound speed variations. Of course, the resulting measurements refer to quantities integrated along these ray paths. An inversion technique based on Fermat's principle has been developed and used to map the flow velocities and sound speed variations as a function of horizontal position and depth. The MDI experiment on SOHO makes doppler shift maps with 1Kx1K points in two choices of image scale, 2 and 0.6 arcsec/pixel. For the present study, we have used the higher resolution mode to observe 8.5 hours of doppler maps sampled once per minute. In order to average enough crosscorrelations to see time-distance effects, the resultant time-distance maps are reduced in resolution by a factor of 10 from the initial data. This still yields about 7 samples across a single supergranulation cell, or 49 over the area of a square cell. Our initial inversions based on the ray theory suggest that the supergranulation flow extends at least to 0.5% of the solar radius below the surface. This research is supported by the SOI-MDI NASA contract NAG5-3077 at Stanford University.

  1. Spatial Variation of Phosphorous Retention Capacity in Subsurface Flow Constructed Wetlands: Effect of Wetland Type and Inflow Loading.

    Directory of Open Access Journals (Sweden)

    Guangwei Yu

    Full Text Available For verification of spatial distribution of phosphorous retention capacity in constructed wetlands systems(CWs, two horizontal subsurface flow(HSSF CWs and two vertical subsurface flow(VSSF CWs, using sand as substrate and Typha latifolia as wetland plants, were constructed and put into use for synthetic wastewater treatment. Five months later, significant spatial variations of TP and inorganic phosphorus(Ca-P, Fe-P and Al-P were observed, which were found to be greatly affected by CWs type and hydraulic loading. The results revealed that though spatial distribution of Fe-P and Al-P displayed a similar order of substrate content as "rhizosphere" > "near-rhizosphere" > "non-rhizosphere" and "inflow section" > "outflow section" regardless of types and loading, the distribution of Ca-P was positively correlated to that of Fe-P and Al-P in HSSF CWs, while negative correlation was shown in VSSF CWs. As a result, TP spatial distribution in HSSF CWs demonstrated a greater dissimilarity than that in VSSF CWs. For HSSF CWs with low hydraulic loading, the lowest TP content was found in non-rhizosphere substrate of outflow section, while the highest one was discovered in rhizonsphere substrate of inflow section. The values in 6 parts of areas ranged from 0.138 g·kg-1 to 2.710 g·kg-1, which also were from -33.5% to 1209% compared to the control value. On contrast, spatial difference of TP content in substrates of VSSF CWs was insignificant, with a variation ranging from 0.776 g·kg-1 to 1.080 g·kg-1, that was 275% to 421% higher than the control value. In addition, when hydraulic loading was increased, TP content in VSSF CWs sharply decreased, ranging from 0.210 g·kg-1 to 0.634 g·kg-1. Meanwhile, dissimilarity of TP spatial distribution in HSSF CWs was reduced, with TP content ranging from 0.258 g·kg-1 to 2.237 g·kg-1. The results suggested that P spatial distribution should be taken into account for CWs design and operation.

  2. Spatial Variation of Phosphorous Retention Capacity in Subsurface Flow Constructed Wetlands: Effect of Wetland Type and Inflow Loading

    Science.gov (United States)

    Yu, Guangwei; Tan, Meijuan; Chong, Yunxiao; Long, Xinxian

    2015-01-01

    For verification of spatial distribution of phosphorous retention capacity in constructed wetlands systems(CWs), two horizontal subsurface flow(HSSF) CWs and two vertical subsurface flow(VSSF) CWs, using sand as substrate and Typha latifolia as wetland plants, were constructed and put into use for synthetic wastewater treatment. Five months later, significant spatial variations of TP and inorganic phosphorus(Ca-P, Fe-P and Al-P) were observed, which were found to be greatly affected by CWs type and hydraulic loading. The results revealed that though spatial distribution of Fe-P and Al-P displayed a similar order of substrate content as "rhizosphere" > "near-rhizosphere" > "non-rhizosphere" and "inflow section" > "outflow section" regardless of types and loading, the distribution of Ca-P was positively correlated to that of Fe-P and Al-P in HSSF CWs, while negative correlation was shown in VSSF CWs. As a result, TP spatial distribution in HSSF CWs demonstrated a greater dissimilarity than that in VSSF CWs. For HSSF CWs with low hydraulic loading, the lowest TP content was found in non-rhizosphere substrate of outflow section, while the highest one was discovered in rhizonsphere substrate of inflow section. The values in 6 parts of areas ranged from 0.138 g·kg-1 to 2.710 g·kg-1, which also were from -33.5% to 1209% compared to the control value. On contrast, spatial difference of TP content in substrates of VSSF CWs was insignificant, with a variation ranging from 0.776 g·kg-1 to 1.080 g·kg-1, that was 275% to 421% higher than the control value. In addition, when hydraulic loading was increased, TP content in VSSF CWs sharply decreased, ranging from 0.210 g·kg-1 to 0.634 g·kg-1. Meanwhile, dissimilarity of TP spatial distribution in HSSF CWs was reduced, with TP content ranging from 0.258 g·kg-1 to 2.237 g·kg-1. The results suggested that P spatial distribution should be taken into account for CWs design and operation. PMID:26218872

  3. Spatial Variation of Phosphorous Retention Capacity in Subsurface Flow Constructed Wetlands: Effect of Wetland Type and Inflow Loading.

    Science.gov (United States)

    Yu, Guangwei; Tan, Meijuan; Chong, Yunxiao; Long, Xinxian

    2015-01-01

    For verification of spatial distribution of phosphorous retention capacity in constructed wetlands systems(CWs), two horizontal subsurface flow(HSSF) CWs and two vertical subsurface flow(VSSF) CWs, using sand as substrate and Typha latifolia as wetland plants, were constructed and put into use for synthetic wastewater treatment. Five months later, significant spatial variations of TP and inorganic phosphorus(Ca-P, Fe-P and Al-P) were observed, which were found to be greatly affected by CWs type and hydraulic loading. The results revealed that though spatial distribution of Fe-P and Al-P displayed a similar order of substrate content as "rhizosphere" > "near-rhizosphere" > "non-rhizosphere" and "inflow section" > "outflow section" regardless of types and loading, the distribution of Ca-P was positively correlated to that of Fe-P and Al-P in HSSF CWs, while negative correlation was shown in VSSF CWs. As a result, TP spatial distribution in HSSF CWs demonstrated a greater dissimilarity than that in VSSF CWs. For HSSF CWs with low hydraulic loading, the lowest TP content was found in non-rhizosphere substrate of outflow section, while the highest one was discovered in rhizonsphere substrate of inflow section. The values in 6 parts of areas ranged from 0.138 g·kg-1 to 2.710 g·kg-1, which also were from -33.5% to 1209% compared to the control value. On contrast, spatial difference of TP content in substrates of VSSF CWs was insignificant, with a variation ranging from 0.776 g·kg-1 to 1.080 g·kg-1, that was 275% to 421% higher than the control value. In addition, when hydraulic loading was increased, TP content in VSSF CWs sharply decreased, ranging from 0.210 g·kg-1 to 0.634 g·kg-1. Meanwhile, dissimilarity of TP spatial distribution in HSSF CWs was reduced, with TP content ranging from 0.258 g·kg-1 to 2.237 g·kg-1. The results suggested that P spatial distribution should be taken into account for CWs design and operation.

  4. Use of Groundwater Chemistry to Evaluate Subsurface Flow at Yucca Mountain, Nevada

    Science.gov (United States)

    Coleman, N. M.; Dam, W. L.

    2001-12-01

    Yucca Mountain, Nevada is a potential site for the disposal of high-level nuclear wastes. Groundwater at the site occurs in Tertiary volcanic tuffs and in Quaternary valley fill alluvium at lower elevations in the Amargosa Desert. Groundwater seeps downward to the water table through a thick unsaturated zone (UZ), then flows south and southeasterly from Yucca Mountain toward Fortymile Wash. The wash is a highly ephemeral watercourse that drains Fortymile Canyon and Jackass Flats southward. The wash crosses Highway 95 just west of Lathrop Wells, Nevada. Water table contours in Jackass Flats show that groundwater flow strongly converges on the axis of Fortymile Wash, indicating that the same structural conditions that cause topographic lows in the area also enhance the southerly flow of groundwater. Groundwater chemistry is being used to evaluate flow conditions at local and regional scales, and to help resolve technical issues concerning UZ and saturated zone (SZ) flow conditions and dilution processes. A number of perched zones have been found beneath Yucca Mt. in five different wells (Patterson et al., 1998). The major element chemistry of perched water is distinct from pore water chemistry in the UZ and more similar to the water chemistry of the SZ. The perched water is more dilute than the UZ pore waters, with generally lower chloride concentrations. The lower chloride concentration suggests that a fraction of the perched water is recharge that moves downward from the surface through fractures, and has less interaction with the host rock than pore waters. However, only 1 of 5 wells yielded perched water with bomb-pulse levels of tritium. Deuterium and O-18 stable isotope chemistry indicates that perched water has an intermediate composition when compared to SZ groundwater. It is isotopically heavier (less negative) than SZ water beneath Yucca Mountain, but lighter than groundwater from wells along Fortymile Wash where significant recharge occurs. The heaviest

  5. Heat-flow and subsurface temperature history at the site of Saraya (eastern Senegal)

    Science.gov (United States)

    Lucazeau, F.; Rolandone, F.

    2012-08-01

    New temperature measurements from eight boreholes in the West African Craton (WAC) reveal superficial perturbations down to 100 m below the alteration zone. These perturbations are both related to a recent increase in the surface air temperature (SAT) and to the site effects caused by fluid circulations and/or the lower conduction in the alterites. The ground surface temperature (GST), inverted from the boreholes temperatures, increased slowly in the past (~0.4 °C from 1700 to 1940) and then, more importantly, in recent years (~1.5 °C from 1940 to 2010). This recent trend is consistent with the increase of the SAT recorded at two nearby meteorological stations (Tambacounda and Kedougou), and more generally in the Sahel with a coeval rainfall decrease. Site effects are superimposed to the climatic effect and interpreted by advective (circulation of fluids) or conductive (lower conductivity of laterite and of high-porosity sand) perturbations. We used a 1-D finite differences thermal model and a Monte-Carlo procedure to find the best estimates of these site perturbations: all the eight borehole temperature logs can be interpreted with the same basal heat-flow and the same surface temperature history, but with some realistic changes of thermal conductivity and/or fluid velocity. The GST trend observed in Senegal can be confirmed by two previous borehole measurements made in 1983 in other locations of West Africa, the first one in an arid zone of northern Mali and the second one in a sub-humid zone in southern Mali. Finally, the background heat-flow is low (31±2 mW m-2), which makes this part of the WAC more similar with the observations in the southern part (33±8 mW m-2) rather than with those in the northern part and in the Pan-African domains where the surface heat-flow is 15-20 mW m-2 higher.

  6. Heat-flow and subsurface temperature history at the site of Saraya (eastern Senegal

    Directory of Open Access Journals (Sweden)

    F. Lucazeau

    2012-06-01

    Full Text Available New temperature measurements from eight boreholes in the West African Craton (WAC reveal superficial perturbations down to 100 meters below the alteration zone. These perturbations are both related to a recent increase of the surface air temperature (SAT and to the site effects caused by fluids circulations and/or the lower conduction in the alterites. The ground surface temperature (GST inverted from the boreholes temperatures is stable in the past (1700–1940 and then dramatically increases in the most recent years (1.5 °C since 1950. This is consistent with the increase of the SAT recorded at two nearby meteorological stations (Tambacounda and Kedougou, and more generally in the Sahel with a coeval rainfall decrease. Site effects are superimposed to the climatic effect and interpreted by advective (circulation of fluids or conductive (lower conductivity of laterite and of high-porosity sand perturbations. We used a 1-D finite differences thermal model and a Monte-Carlo procedure to find the best estimates of these sites perturbations: all the eight boreholes temperatures logs can be interpreted with the same basal heat-flow and the same surface temperature history, but with some realistic changes of thermal conductivity and/or fluid velocity. The GST trend observed in Senegal can be confirmed by two previous boreholes measurements made in 1983 in other locations of West Africa, the first one in an arid zone of northern Mali and the second one in a subhumid zone in southern Mali. Finally, the background heat-flow is low (30 ± 1 m Wm−2, which makes this part of the WAC more similar with the observations in the southern part (33 ± 8 m Wm−2 rather than with those in the northern part and in the PanAfrican domains where the surface heat-flow is 15–20 m Wm−2 higher.

  7. Some Examples of the Application and Validation of the NUFT Subsurface Flow and Transport Code

    Energy Technology Data Exchange (ETDEWEB)

    Nitao, J J

    2001-08-01

    This report was written as partial fulfillment of a subcontract from DOD/DOE Strategic Environmental Research and Development Program (SERDP) as part of a project directed by the U.S. Army Engineer Research and Development Center, Waterways Experiment Station (WES), Vicksburg, Mississippi. The report documents examples of field validation of the Non-isothermal Unsaturated-saturated Flow and Transport model (NUFT) code for environmental remediation, with emphasis on soil vapor extraction, and describes some of the modifications needed to integrate the code into the DOD Groundwater Modeling System (GMS, 2000). Note that this report highlights only a subset of the full capabilities of the NUFT code.

  8. Dairy farm wastewater treatment using horizontal subsurface flow wetlands with Typha domingensis and different substrates.

    Science.gov (United States)

    Schierano, María Celeste; Maine, María Alejandra; Panigatti, María Cecilia

    2017-01-01

    The aim of this work was to evaluate the influence of different substrates in the performance of a horizontal flow constructed wetland employed in dairy farm wastewater treatment. Typha domingensis was chosen for this study due to its high productivity and efficiency in nutrient removal. Fifteen microcosm-scale reactors simulating horizontal flow constructed wetlands were disposed in a greenhouse in triplicate. Five substrates (river gravel, gravel, LECA, river gravel + zeolite and gravel + zeolite) were evaluated. Real effluent with previous treatment was used. Dairy farm effluents favoured T. domingensis growth, probably due to their high nutrient concentrations. The treatments with the different substrates studied were efficient in the treatment of the dairy farm effluent obtaining ammonium ([Formula: see text]) and total phosphorus (TP) removals between 88-99% and 86-99%, respectively. Removal efficiencies were significantly higher in treatments using LECA and combined substrate (gravel + zeolite). After treatment, the quality of the final effluent was significantly improved. Outlet effluent complied with regulations and could be discharged into the environment.

  9. Modelling and Simulation of Structural Deformation of Isothermal Subsurface Flow and Carbon Dioxide Injection

    KAUST Repository

    El-Amin, Mohamed

    2011-05-15

    Injection of CO2 in hydrocarbon reservoir has double benefit. On the one hand, it is a profitable method due to issues related to global warming, and on the other hand it is an effective mechanism to enhance hydrocarbon recovery. Such injection associates complex processes involving, e.g., solute transport of dissolved materials, in addition to local changes in density of the phases. Also, increasing carbon dioxide injection may cause a structural deformation of the medium, so it is important to include such effect into the model. The structural deformation modelling in carbon sequestration is important to evaluate the medium stability to avoid CO2 leakage to the atmosphere. On the other hand, geologic formation of the medium is usually heterogeneous and consists of several layers of different permeability. In this work we conduct numerical simulation of two-phase flow in a heterogeneous porous medium domain with dissolved solute transport as well as structural deformation effects. The solute transport of the dissolved component is described by concentration equation. The structural deformation for geomechanics is derived from a general local differential balance equation with neglecting the local mass balance of solid phase and the inertial force term. The flux continuity condition is used at interfaces between different permeability layers of the heterogeneous medium. We analyze the vertical migration of a CO2 plume injected into a 2D layered reservoir. Analysis of distribution of flow field components such as saturation, pressures, velocities, and CO2 concentration are presented.

  10. Flow Alteration and Chemical Reduction: Air Stripping to Lessen Subsurface Discharges of Mercury to Surface Water

    Science.gov (United States)

    Brooks, S. C.; Bogle, M.; Liang, L.; Miller, C. L.; Peterson, M.; Southworth, G. R.; Spalding, B. P.

    2009-12-01

    Mercury concentrations in groundwater, surface water, and biota near an industrial facility in Oak Ridge, Tennessee remain high some 50 years after the original major releases from the facility to the environment. Since the mid-1980s, various remedial and abatement actions have been implemented at the facility, including re-routing water flows, armoring contaminated stream banks, relining or cleanout of facility storm drains, and activated charcoal treatment of groundwater and sump discharges. These actions were taken to reduce inorganic mercury inputs from the facility to the stream; a strategy that assumes limiting the inorganic mercury precursor will reduce Hg methylation and its subsequent bioaccumulation. To date, such actions have reduced mercury loading from the site by approximately 90% from levels typical of the mid 1980's, but waterborne mercury at the facility boundary remains roughly 100 times the typical local background concentration and methylmercury accumulation in aquatic biota exceed standards for safe consumption by humans and wildlife. In 2008 and 2009, a series of investigations was initiated to explore innovative approaches to further control mercury concentrations in stream water. Efforts in this study focused on decreasing waterborne inorganic mercury inputs from two sources. The first, a highly localized source, is the discharge point of the enclosed stormdrain network whereas the second is a more diffuse short reach of stream where metallic Hg in streambed sediments generates a continued input of dissolved Hg to the overlying water. Moving a clean water flow management discharge point to a position downstream of the contaminated reach reduced mercury loading from the streambed source by 75% - 100%, likely by minimizing resuspension of Hg-rich fine particulates and changing characteristic hyporheic flow path length and residence time. Mercury in the stormdrain discharge exists as highly reactive dissolved Hg(II) due to residual chlorine in

  11. Heat-flow and subsurface temperature history at the site of Saraya (eastern Senegal

    Directory of Open Access Journals (Sweden)

    F. Lucazeau

    2012-08-01

    Full Text Available New temperature measurements from eight boreholes in the West African Craton (WAC reveal superficial perturbations down to 100 m below the alteration zone. These perturbations are both related to a recent increase in the surface air temperature (SAT and to the site effects caused by fluid circulations and/or the lower conduction in the alterites. The ground surface temperature (GST, inverted from the boreholes temperatures, increased slowly in the past (~0.4 °C from 1700 to 1940 and then, more importantly, in recent years (~1.5 °C from 1940 to 2010. This recent trend is consistent with the increase of the SAT recorded at two nearby meteorological stations (Tambacounda and Kedougou, and more generally in the Sahel with a coeval rainfall decrease. Site effects are superimposed to the climatic effect and interpreted by advective (circulation of fluids or conductive (lower conductivity of laterite and of high-porosity sand perturbations. We used a 1-D finite differences thermal model and a Monte-Carlo procedure to find the best estimates of these site perturbations: all the eight borehole temperature logs can be interpreted with the same basal heat-flow and the same surface temperature history, but with some realistic changes of thermal conductivity and/or fluid velocity. The GST trend observed in Senegal can be confirmed by two previous borehole measurements made in 1983 in other locations of West Africa, the first one in an arid zone of northern Mali and the second one in a sub-humid zone in southern Mali. Finally, the background heat-flow is low (31±2 mW m−2, which makes this part of the WAC more similar with the observations in the southern part (33±8 mW m−2 rather than with those in the northern part and in the Pan-African domains where the surface heat-flow is 15–20 mW m−2 higher.

  12. Ecohydrologic Investigations of Shallow Lateral Subsurface Flow in Tropical Soils using Time-Lapse Surface Electrical Resistivity Tomography

    Science.gov (United States)

    Ogden, F. L.; Mojica, A.; Abebe, N. A.; Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project

    2010-12-01

    The hydrologic effects of deforestation and aforestation in the tropics remain an area of active research. Hydrologic predictions of land-use change effects remain elusive. One of the unique features of catchment hydrology in the tropics is the effect of intense, continuous biological activity by insects, shrubs, trees, and small mammals. Sapprolitic soils derived from weathered bedrock cover widespread areas. These soils have low matrix permeabilities on the order of 1 mm/h, are 10 to 20 m in thickness and have relatively low activity because they have been depleted of light cations by annual rainfall over 2000 mm. As part of the Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project, we have observed shallow subsurface flow in tropical soils in central Panama using an introduced salinity contrast and surface electrical resistivity tomography (ERT). In 2009 and 2010, experiments were conducted in a 30 year-old secondary succession forest, and in two former pasture sites that were planted with native timber species and teak, respectively, in 2008. At each site, saline water (NaCl tagged with LiBr) was introduced to the soil using two different methods: soil pits and ponded surface applications. Results showed the strongest response in the case of ponded surface applications with observed changes in resistivity between -50% and 50%. In soil pit applications, the change in electrical resistivity varied from -10% to 10%. Results suggest that in the case of surface application, a transient perched water table is created near the bottom of the bioturbation layer that activates the downslope macropore network and results in bulk flow velocities that are significantly higher than observed soil matrix permeabilities. When heavy rainfall occurred during tests, increased mobility of the salinity contrast more clearly showed the active layer where most flow occurred. Time-series ERT observations enabled measurements of downslope bulk

  13. Model-based evaluation of subsurface monitoring networks for improved efficiency and predictive certainty of regional groundwater models

    Science.gov (United States)

    Gosses, M. J.; Wöhling, Th.; Moore, C. R.; Dann, R.; Scott, D. M.; Close, M.

    2012-04-01

    Groundwater resources worldwide are increasingly under pressure. Demands from different local stakeholders add to the challenge of managing this resource. In response, groundwater models have become popular to make predictions about the impact of different management strategies and to estimate possible impacts of changes in climatic conditions. These models can assist to find optimal management strategies that comply with the various stakeholder needs. Observations of the states of the groundwater system are essential for the calibration and evaluation of groundwater flow models, particularly when they are used to guide the decision making process. On the other hand, installation and maintenance of observation networks are costly. Therefore it is important to design monitoring networks carefully and cost-efficiently. In this study, we analyse the Central Plains groundwater aquifer (~ 4000 km2) between the Rakaia and Waimakariri rivers on the Eastern side of the Southern Alps in New Zealand. The large sedimentary groundwater aquifer is fed by the two alpine rivers and by recharge from the land surface. The area is mainly under agricultural land use and large areas of the land are irrigated. The other major water use is the drinking water supply for the city of Christchurch. The local authority in the region, Environment Canterbury, maintains an extensive groundwater quantity and quality monitoring programme to monitor the effects of land use and discharges on groundwater quality, and the suitability of the groundwater for various uses, especially drinking-water supply. Current and projected irrigation water demand has raised concerns about possible impacts on groundwater-dependent lowland streams. We use predictive uncertainty analysis and the Central Plains steady-state groundwater flow model to evaluate the worth of pressure head observations in the existing groundwater well monitoring network. The data worth of particular observations is dependent on the problem

  14. Particle methods for simulation of subsurface multiphase fluid flow and biogeological processes

    Energy Technology Data Exchange (ETDEWEB)

    Meakin, Paul; Tartakovsky, Alexandre M.; Scheibe, Timothy D.; Tartakovsky, Daniel M.; Redden, George; Long, Philip E.; Brooks, Scott C.; Xu, Zhijie

    2007-08-01

    A number of particle models that are suitable for simulating multiphase fluid flow and biogeological processes have been developed during the last few decades. Here we discuss three of them: a microscopic model - molecular dynamics; a mesoscopic model - dissipative particle dynamics; and a macroscopic model - smoothed particle hydrodynamics. Particle methods are robust and versatile, and it is relatively easy to add additional physical, chemical and biological processes into particle codes. However, the computational efficiency of particle methods is low relative to continuum methods. Multiscale particle methods and hybrid (particle–particle and particle–continuum) methods are needed to improve computational efficiency and make effective use of emerging computational capabilities. These new methods are under development.

  15. Particle methods for simulation of subsurface multiphase fluid flow and biogeological processes

    Energy Technology Data Exchange (ETDEWEB)

    Paul Meakin; Alexandre Tartakovsky; Tim Scheibe; Daniel Tartakovsky; Georgr Redden; Philip E. Long; Scott C. Brooks; Zhijie Xu

    2007-06-01

    A number of particle models that are suitable for simulating multiphase fluid flow and biogeological processes have been developed during the last few decades. Here we discuss three of them: a microscopic model - molecular dynamics; a mesoscopic model - dissipative particle dynamics; and a macroscopic model - smoothed particle hydrodynamics. Particle methods are robust and versatile, and it is relatively easy to add additional physical, chemical and biological processes into particle codes. However, the computational efficiency of particle methods is low relative to continuum methods. Multiscale particle methods and hybrid (particle–particle and particle–continuum) methods are needed to improve computational efficiency and make effective use of emerging computational capabilities. These new methods are under development.

  16. A two-stage subsurface vertical flow constructed wetland for high-rate nitrogen removal.

    Science.gov (United States)

    Langergraber, Guenter; Leroch, Klaus; Pressl, Alexander; Rohrhofer, Roland; Haberl, Raimund

    2008-01-01

    By using a two-stage constructed wetland (CW) system operated with an organic load of 40 gCOD.m(-2).d(-1) (2 m2 per person equivalent) average nitrogen removal efficiencies of about 50% and average nitrogen elimination rates of 980 g N.m(-2).yr(-1) could be achieved. Two vertical flow beds with intermittent loading have been operated in series. The first stage uses sand with a grain size of 2-3.2 mm for the main layer and has a drainage layer that is impounded; the second stage sand with a grain size of 0.06-4 mm and a drainage layer with free drainage. The high nitrogen removal can be achieved without recirculation thus it is possible to operate the two-stage CW system without energy input. The paper shows performance data for the two-stage CW system regarding removal of organic matter and nitrogen for the two year operating period of the system. Additionally, its efficiency is compared with the efficiency of a single-stage vertical flow CW system designed and operated according to the Austrian design standards with 4 m2 per person equivalent. The comparison shows that a higher effluent quality could be reached with the two-stage system although the two-stage CW system is operated with the double organic load or half the specific surface area requirement, respectively. Another advantage is that the specific investment costs of the two-stage CW system amount to 1,200 EUR per person (without mechanical pre-treatment) and are only about 60% of the specific investment costs of the singe-stage CW system. IWA Publishing 2008.

  17. EFFLUENT TREATMENT OF PHARMACEUTICAL INDUSTRY BY USING SUBSURFACE FLOW WETLAND SYSTEM

    Directory of Open Access Journals (Sweden)

    Mega Anggraeni

    2014-04-01

    Full Text Available Constructed wetland is one of the alternatives to increase water quality before it flowed into waterways. Sub Surface Flow Wetland System is one type of the constructed wetland for waste water treatment which is using symbiotic relation between water plants and microorganism around rooting system (rhizosphere in media. Cyperus alternifolius and Canna indica, L. as well as gravel and sand media are plants and medias that can be used in constructed wetland. This research aimed to analyze the effectiveness of plant species between Cyperus alternifolius and Canna indica, L. as well as the effectiveness of gravel and sand media to decrease nitrite, ammoniak, BOD, and COD concentrations. Four reactors SSF-Wetlands with dimension of 120 cm x 30 cm x 50 cm were used in this research. The study was conducted over 12 days following the  acclimatization of plants for 7 days. Data analysis were performed by comparing the degradation coefficient (k of BOD, COD, nitrite, and ammonia concentrations with retention time of the effluent. The results showed that  the degradation rate for the reactor with with gravel media and Cyperus alternifolius for nitrite variable was 0.60,  ammonia 0.49, BOD 0.45, and COD 0.36. Cyperus alternifolius have a higher effectiveness in reducing the concentration of nitrite, ammonia , BOD and COD than Canna indica , L. Reactors with gravel media have higher effectiveness in reducing BOD , COD , ammonia and nitrite concentration than sand media. Keywords : Canna indica. L. , Cyperus alternifolius, SSF - Wetland, , WWTP effluent of pharmaceutical industry

  18. Impact of Geological Characterization Uncertainties on Subsurface Flow & Transport Using a Stochastic Discrete Fracture Network Approach

    Science.gov (United States)

    Ezzedine, S. M.

    2009-12-01

    Fractures and fracture networks are the principal pathways for transport of water and contaminants in groundwater systems, enhanced geothermal system fluids, migration of oil and gas, carbon dioxide leakage from carbon sequestration sites, and of radioactive and toxic industrial wastes from underground storage repositories. A major issue to overcome when characterizing a fractured reservoir is that of data limitation due to accessibility and affordability. Moreover, the ability to map discontinuities in the rock with available geological and geophysical tools tends to decrease particularly as the scale of the discontinuity goes down. Geological characterization data include measurements of fracture density, orientation, extent, and aperture, and are based on analysis of outcrops, borehole optical and acoustic televiewer logs, aerial photographs, and core samples, among other techniques. All of these measurements are taken at the field scale through a very sparse limited number of deep boreholes. These types of data are often reduced to probability distribution functions for predictive modeling and simulation in a stochastic framework such as a stochastic discrete fracture network. Stochastic discrete fracture network models enable, through Monte Carlo realizations and simulations, probabilistic assessment of flow and transport phenomena that are not adequately captured using continuum models. Despite the fundamental uncertainties inherited within the probabilistic reduction of the sparse data collected, very little work has been conducted on quantifying uncertainty on the reduced probabilistic distribution functions. In the current study, using nested Monte Carlo simulations, we present the impact of parameter uncertainties of the distribution functions of fracture density, orientation, aperture and size on the flow and transport using topological measures such as fracture connectivity, physical characteristics such as effective hydraulic conductivity tensors, and

  19. Phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia in a horizontal subsurface flow constructed wetland.

    Science.gov (United States)

    Li, Yifei; Zhang, Jiefeng; Zhu, Guibing; Liu, Yu; Wu, Bing; Ng, Wun Jern; Appan, Adhityan; Tan, Soon Keat

    2016-10-01

    Widespread occurrence of trace pharmaceutical residues in aquatic environments is of great concerns due to the potential chronic toxicity of certain pharmaceuticals including ibuprofen on aquatic organisms even at environmental levels. In this study, the phytoextraction, phytotransformation and rhizodegradation of ibuprofen associated with Typha angustifolia were investigated in a horizontal subsurface flow constructed wetland system. The experimental wetland system consisted of a planted bed with Typha angustifolia and an unplanted bed (control) to treat ibuprofen-loaded wastewater (∼107.2 μg L(-1)). Over a period of 342 days, ibuprofen was accumulated in leaf sheath and lamina tissues at a mean concentration of 160.7 ng g(-1), indicating the occurrence of the phytoextraction of ibuprofen. Root-uptake ibuprofen was partially transformed to ibuprofen carboxylic acid, 2-hydroxy ibuprofen and 1-hydroxy ibuprofen which were found to be 1374.9, 235.6 and 301.5 ng g(-1) in the sheath, respectively, while they were 1051.1, 693.6 and 178.7 ng g(-1) in the lamina. The findings from pyrosequencing analysis of the rhizosphere bacteria suggest that the Dechloromonas sp., the Clostridium sp. (e.g. Clostridium saccharobutylicum), the order Sphingobacteriales, and the Cytophaga sp. in the order Cytophagales were most probably responsible for the rhizodegradation of ibuprofen. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Pathways of nitrobenzene degradation in horizontal subsurface flow constructed wetlands: Effect of intermittent aeration and glucose addition.

    Science.gov (United States)

    Kirui, Wesley K; Wu, Shubiao; Kizito, Simon; Carvalho, Pedro N; Dong, Renjie

    2016-01-15

    Intermittent aeration and addition of glucose were applied to horizontal subsurface flow constructed wetlands in order to investigate the effect on pathways of nitrobenzene (NB) degradation and interactions with microbial nitrogen and sulphur transformations. The experiment was carried out in three phases A, B and C consisting of different NB loading and glucose dosing. For each phase, the effect of aeration was assessed by intermittently aerating one wetland and leaving one unaerated. Regardless of whether or not the wetland was aerated, at an influent NB concentration of 140 mg/L, both wetlands significantly reduced NB to less than 2 mg/L, a reduction efficiency of 98%. However, once the influent NB concentration was increased to 280 mg/L, the aerated wetland had a higher removal performance 82% compared to that of the unaerated wetland 71%. Addition of glucose further intensified the NB removal to 95% in the aerated wetlands and 92% in the unaerated. Aeration of wetlands enhanced NB degradation, but also resulted in higher NB volatilization of 6 mg m(-2) d(-1). The detected high concentration of sulphide 20-60 mg/L in the unaerated wetland gave a strong indication that NB may act as an electron donor to sulphate-reducing bacteria, but this should be further investigated. Aeration positively improved NB removal in constructed wetlands, but resulted in higher NB volatilization. Glucose addition induced co-metabolism to enhance NB degradation.

  1. Nitrogen removal performance in planted and unplanted horizontal subsurface flow constructed wetlands treating different influent COD/N ratios.

    Science.gov (United States)

    Wang, Wei; Ding, Yi; Ullman, Jeffrey L; Ambrose, Richard F; Wang, Yuhui; Song, Xinshan; Zhao, Zhimiao

    2016-05-01

    Microcosm horizontal subsurface flow constructed wetlands (HSSFCWs) were used to examine the impacts of vegetation on nitrogen dynamics treating different influent COD/N ratios (1:1, 4:1, and 8:1). An increase in the COD/N ratio led to increased reductions in NO3 and total inorganic nitrogen (TIN) in planted and unplanted wetlands, but diminished removal of NH4. The HSSFCW planted with Canna indica L. exhibited a significant reduction in NH4 compared to the unplanted system, particularly in the active root zone where NH4 removal performance increased by up to 26 % at the COD/N ratio of 8:1. There was no significant difference in NO3 removal between the planted and unplanted wetlands. TIN removal efficiency in the planted wetland increased with COD/N ratios, which was likely influenced by plant uptake. NH4 reductions were greater in planted wetland at the 20- and 40-cm depths while NO3 reductions were uniformly greater with depth in all cases, but no statistical difference was impacted by depth on TIN removal. These findings show that planting a HSSFCW can provide some benefit in reducing nitrogen loads in effluents, but only when a sufficient carbon source is present.

  2. Theoretical analysis of non-Gaussian heterogeneity effects on subsurface flow and transport

    Science.gov (United States)

    Riva, Monica; Guadagnini, Alberto; Neuman, Shlomo P.

    2017-04-01

    Much of the stochastic groundwater literature is devoted to the analysis of flow and transport in Gaussian or multi-Gaussian log hydraulic conductivity (or transmissivity) fields, Y(x)=ln\\func K(x) (x being a position vector), characterized by one or (less frequently) a multiplicity of spatial correlation scales. Yet Y and many other variables and their (spatial or temporal) increments, ΔY, are known to be generally non-Gaussian. One common manifestation of non-Gaussianity is that whereas frequency distributions of Y often exhibit mild peaks and light tails, those of increments ΔY are generally symmetric with peaks that grow sharper, and tails that become heavier, as separation scale or lag between pairs of Y values decreases. A statistical model that captures these disparate, scale-dependent distributions of Y and ΔY in a unified and consistent manner has been recently proposed by us. This new "generalized sub-Gaussian (GSG)" model has the form Y(x)=U(x)G(x) where G(x) is (generally, but not necessarily) a multiscale Gaussian random field and U(x) is a nonnegative subordinator independent of G. The purpose of this paper is to explore analytically, in an elementary manner, lead-order effects that non-Gaussian heterogeneity described by the GSG model have on the stochastic description of flow and transport. Recognizing that perturbation expansion of hydraulic conductivity K=eY diverges when Y is sub-Gaussian, we render the expansion convergent by truncating Y's domain of definition. We then demonstrate theoretically and illustrate by way of numerical examples that, as the domain of truncation expands, (a) the variance of truncated Y (denoted by Yt) approaches that of Y and (b) the pdf (and thereby moments) of Yt increments approach those of Y increments and, as a consequence, the variogram of Yt approaches that of Y. This in turn guarantees that perturbing Kt=etY to second order in σYt (the standard deviation of Yt) yields results which approach those we obtain

  3. Integrated surface-subsurface water flow modelling of the Laxemar area. Application of the hydrological model ECOFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Sokrut, Nikolay; Werner, Kent; Holmen, Johan [Golder Associates AB, Uppsala (Sweden)

    2007-01-15

    Since 2002, the Swedish Nuclear Fuel and Waste Management Co (SKB) performs site investigations in the Simpevarp area, for the siting of a deep geological repository for spent nuclear fuel. The site descriptive modelling includes conceptual and quantitative modelling of surface-subsurface water interactions, which are key inputs to safety assessment and environmental impact assessment. Such modelling is important also for planning of continued site investigations. In this report, the distributed hydrological model ECOFLOW is applied to the Laxemar subarea to test the ability of the model to simulate surface water and near-surface groundwater flow, and to illustrate ECOFLOW's advantages and drawbacks. The ECOFLOW model area is generally characterised by large areas of exposed or shallow bedrock. The ECOFLOW modelling results are compared to previous results produced by MIKE SHE-MIKE 11 and PCRaster-POLFLOW, in order to check whether non-calibrated surface and subsurface water flows computed by ECOFLOW are consistent with these previous results. The analyses include quantification and comparison of inflow and outflow terms of the water balance, as well as analyses of groundwater recharge-discharge patterns. ECOFLOW is used to simulate a one-year non calibrated period, considering seven catchments (including three areas with direct runoff to the sea) within the Laxemar subarea. The modelling results show the ability of the model to produce reasonable results for a model domain including both porous media (Quaternary deposits) and discontinuous media (bedrock). The results demonstrate notable differences in the specific discharge between the considered catchments, with specific discharge values in the range 157-212 mm/year; the lowest value (the Lake Frisksjoen catchment) may however be erroneous due to numerical instability in the model. Overall, these results agree with specific discharge values computed by MIKE SHE-MIKE 11 and PCRaster-POLFLOW (190 and 128

  4. Monitoring the Dynamics of Water Flow at a High-Mountain Permafrost Site Using Electrical Self-Potential Measurements

    Science.gov (United States)

    Kemna, A.; Weigand, M.; Wagner, F.; Hilbich, C.; Hauck, C.

    2016-12-01

    Flow of (liquid) water plays a crucial role in the dynamics of coupled thermo-hydro-mechanical processes in terrestrial permafrost systems. To better understand these processes in the active layer of permafrost regions, with the ultimate goal of adequately incorporating them in numerical models for improved scenario prediction, monitoring approaches offering high spatial and temporal resolution, areal coverage, and especially sensitivity to subsurface water flow, are highly desired. This particularly holds for high-mountain slopes, where strong variability in topography, precipitation, and snow cover, along with significant subsurface soil/rock heterogeneity, gives rise to complex spatio-temporal patterns of water flow during seasonal thawing and freezing periods. The electrical self-potential (SP) method is well known to, in theory, meeting the above monitoring demands by measuring the electrical streaming potential which is generated at the microscopic scale when water flows along electrically non-neutral interfaces. Despite its inherent sensitivity to subsurface water flow, the SP method has not yet been used for the monitoring of high-mountain permafrost sites. We here present first results from an SP monitoring survey conducted at the Schilthorn (2970 m asl) in the Bernese Alps, Switzerland, where SP data have been collected since September 2013 at a sampling rate of 10 min on a permanently installed array of 12 non-polarizing electrodes covering an area of 35 m by 15 m. While the SP time series exhibit systematic daily variations, with part of the signal clearly correlated with temperature, in particular in the snow-free periods, the largest temporal changes in the SP signal occur in spring, when the snow cover melts and thawing sets on in the active layer. The period of higher temporal SP variations continues until autumn, when the signal gradually returns to relatively low variations, coinciding with the freezing of the ground. Our results suggest that the

  5. Use of soil moisture dynamics and patterns at different spatio-temporal scales for the investigation of subsurface flow processes

    Directory of Open Access Journals (Sweden)

    T. Blume

    2009-07-01

    Full Text Available Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes, especially in data scarce or previously ungauged catchments. The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture response allows for visualization of flow processes in the unsaturated zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale and binary indicator maps (for the long-term and hillslope scale. Annual dynamics of soil moisture and decimeter-scale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a data-scarce catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. The most likely explanation for preferential flow in this catchment is a combination of hydrophobicity, small scale heterogeneity in rainfall due to redistribution in the canopy and strong gradients in unsaturated conductivities leading to

  6. Modelling shallow landslide susceptibility by means of a subsurface flow path connectivity index and estimates of soil depth spatial distribution

    Directory of Open Access Journals (Sweden)

    C. Lanni

    2012-11-01

    Full Text Available Topographic index-based hydrological models have gained wide use to describe the hydrological control on the triggering of rainfall-induced shallow landslides at the catchment scale. A common assumption in these models is that a spatially continuous water table occurs simultaneously across the catchment. However, during a rainfall event isolated patches of subsurface saturation form above an impeding layer and their hydrological connectivity is a necessary condition for lateral flow initiation at a point on the hillslope.

    Here, a new hydrological model is presented, which allows us to account for the concept of hydrological connectivity while keeping the simplicity of the topographic index approach. A dynamic topographic index is used to describe the transient lateral flow that is established at a hillslope element when the rainfall amount exceeds a threshold value allowing for (a development of a perched water table above an impeding layer, and (b hydrological connectivity between the hillslope element and its own upslope contributing area. A spatially variable soil depth is the main control of hydrological connectivity in the model. The hydrological model is coupled with the infinite slope stability model and with a scaling model for the rainfall frequency–duration relationship to determine the return period of the critical rainfall needed to cause instability on three catchments located in the Italian Alps, where a survey of soil depth spatial distribution is available. The model is compared with a quasi-dynamic model in which the dynamic nature of the hydrological connectivity is neglected. The results show a better performance of the new model in predicting observed shallow landslides, implying that soil depth spatial variability and connectivity bear a significant control on shallow landsliding.

  7. Numerical simulation for horizontal subsurface flow constructed wetlands: A short review including geothermal effects and solution bounding in biodegradation procedures

    Science.gov (United States)

    Liolios, K.; Tsihrintzis, V.; Angelidis, P.; Georgiev, K.; Georgiev, I.

    2016-10-01

    Current developments on modeling of groundwater flow and contaminant transport and removal in the porous media of Horizontal Subsurface Flow Constructed Wetlands (HSF CWs) are first reviewed in a short way. The two usual environmental engineering approaches, the black-box and the process-based one, are briefly presented. Next, recent research results obtained by using these two approaches are briefly discussed as application examples, where emphasis is given to the evaluation of the optimal design and operation parameters concerning HSF CWs. For the black-box approach, the use of Artificial Neural Networks is discussed for the formulation of models, which predict the removal performance of HSF CWs. A novel mathematical prove is presented, which concerns the dependence of the first-order removal coefficient on the Temperature and the Hydraulic Residence Time. For the process-based approach, an application example is first discussed which concerns procedures to evaluate the optimal range of values for the removal coefficient, dependent on either the Temperature or the Hydraulic Residence Time. This evaluation is based on simulating available experimental results of pilot-scale units operated in Democritus University of Thrace, Xanthi, Greece. Further, in a second example, a novel enlargement of the system of Partial Differential Equations is presented, in order to include geothermal effects. Finally, in a third example, the case of parameters uncertainty concerning biodegradation procedures is considered and the use of upper and a novel approach is presented, which concerns the upper and the lower solution bound for the practical draft design of HSF CWs.

  8. Nitrogen removal in a pilot-scale subsurface horizontal flow constructed wetland

    Energy Technology Data Exchange (ETDEWEB)

    Del Bubba, M.; Lepri, L. [Florence Univ., Florence (Italy). Dept. of Public Health, Epidemiology and Environmental Analytical Chemistry; Griffini, O.; Tabani, F. [Florentine Division of Water Production and Wastewater Treatment, Municipality of Florence, Florence (Italy)

    2000-10-01

    Nitrogen removal in a pilot-scale submerged flow constructed wetland, planted with Phragmites australis and receiving domestic wastewaters was investigated for two years (November 1997-October 1999). Nitrification and denitrification simultaneously occurred in this system, showing the presence of both aerobic and anaerobic sites. A second-order polynomial regression fit well (R{sup 2} = O.9414) the experimental values of log K{sub T} versus T-20 in the temperature range 5-27{sup 0}C. In addition, a linear trend (R{sup 2} = O.7834) could also be used as a first approximation in a narrower temperature range (10-27{sup 0}C); the rate constant at 20{sup 0}C (K{sub 2}0) for ammonium microbial oxidation was 0.3985 d{sup -}1, which corresponds to a fully developed root zone. [Italian] Per un periodo di due anni (Novembre 1997-Ottobre 1999), e' stata studiata la rimozione dell'azoto in una zona umida costruita a flusso sommerso di tipo pilota, piantumata con Phragmites australis e ricevente acque di scarico di tipo civile. Nel sistema sono avvenuti contemporaneamente sia il processo di nitrificazione che quello di denitrificazione, a dimostrazione della presenza nella rizosfera sia di micrositi aerobici che anaerobici. L'andamento del log K{sub T} in funzione di T-20 nell'intervallo di temperature 5-27{sup 0}C e' ben interpretabile mediante una regressione polinomiale del secondo ordine (R{sup 2} = O.9414). Tuttavia, prendendo in esame i dati relativi ad un intervallo di temperatura piu' ristretto (10-27{sup 0}C), puo' essere utilizzato, in prima approssimazione, un andamento lineare (R{sup 2} O.7834); la costante di velocita' per l'ossidazione microbica dell'ammoniaca a 20{sup 0}C (K{sub 2}0) e' risultata pari a 0.3985 d{sup -}1, che corrisponde a un letto completamente occupato dalle radici.

  9. A review on nitrogen and organics removal mechanisms in subsurface flow constructed wetlands: dependency on environmental parameters, operating conditions and supporting media.

    Science.gov (United States)

    Saeed, Tanveer; Sun, Guangzhi

    2012-12-15

    With the unique advantages of lower operational and maintenance cost, the applications of subsurface flow constructed wetlands for the treatment of wastewater have been increasing rapidly throughout the world. The removal of nitrogen and organics by such systems has gained substantial attention in recent years. In subsurface flow wetlands, the removal of pollutants often relies on a diverse range of co-existing physical, chemical and biological routes, which are vitally dependent on numerous environmental and operational parameters. This paper provides a comprehensive review of wetland structures, classic and novel nitrogen and organics removal mechanisms along with the key environmental parameters and operational conditions that enhance removal in subsurface flow wetland systems. The critical exploration identifies the major environmental parameters such as: pH, DO, and temperature, operational factors i.e. organic carbon availability, loading, feed mode, retention time, recirculation, harvesting, and the complex role (of both parameters) on classical nitrogen and organics removal pathways. Subsequently, the necessity of further extensive research on such factors, for promoting novel nitrogen removal routes in wetland systems has also been highlighted. The expansion of the review on the influence of the unconventional wetland matrix indicates that, the structural differences and inherent properties of these media can support substantial nitrogen and organics removal from wastewater, under optimal operating conditions. Overall, the critical review illustrates the necessity of a profound knowledge on the complicated inter-relationship between nitrogen and organics removal routes, governing environmental and operational parameters, and wetland matrix for improving the treatment performances of subsurface flow wetlands.

  10. Subsurface Characterization and Seismic Monitoring for the Southwest Partnerships Phase III Demonstration Project at Farnsworth Field, TX

    Science.gov (United States)

    Will, R. A.; Balch, R. S.

    2015-12-01

    The Southwest Partnership on Carbon Sequestration is performing seismic based characterization and monitoring activities at an active CO2 EOR project at Farnsworth Field, Texas. CO2 is anthropogenically sourced from a fertilizer and an ethanol plant. The field has 13 CO2 injectors and has sequestered 302,982 metric tonnes of CO2 since October 2013. The field site provides an excellent laboratory for testing a range of monitoring technologies in an operating CO2 flood since planned development is sequential and allows for multiple opportunities to record zero CO2 baseline data, mid-flood data, and fully flooded data. The project is comparing and contrasting several scales of seismic technologies in order to determine best practices for large scale commercial sequestration projects. Characterization efforts include an 85 km2 3D surface seismic survey, baseline and repeat 3D VSP surveys centered on injection wells, cross-well tomography baseline and repeat surveys between injector/producer pairs, and a borehole passive seismic array to monitor induced seismicity. All surveys have contributed to detailed geologic models which were then used for fluid flow and risk assessment simulations. 3D VSP and cross-well data with repeat surveys have allowed for direct comparisons of the reservoir prior to CO2 injection and at eight months into injection, with a goal of imaging the CO2 plume as it moves away from injection wells. Additional repeat surveys at regular intervals will continue to refine the plume. The goal of this work is to demonstrate seismic based technologies to monitor CO2 sequestration projects, and to contribute to best practices manuals for commercial scale CO2 sequestration projects. In this talk the seismic plan will be outlined, progress towards goals enumerated, and preliminary results from baseline and repeat seismic data will be discussed. Funding for this project is provided by the U.S. Department of Energy under Award No. DE-FC26-05NT42591.

  11. Nitrogen Removal in a Horizontal Subsurface Flow Constructed Wetland Estimated Using the First-Order Kinetic Model

    Directory of Open Access Journals (Sweden)

    Lijuan Cui

    2016-11-01

    Full Text Available We monitored the water quality and hydrological conditions of a horizontal subsurface constructed wetland (HSSF-CW in Beijing, China, for two years. We simulated the area-based constant and the temperature coefficient with the first-order kinetic model. We examined the relationships between the nitrogen (N removal rate, N load, seasonal variations in the N removal rate, and environmental factors—such as the area-based constant, temperature, and dissolved oxygen (DO. The effluent ammonia (NH4+-N and nitrate (NO3−-N concentrations were significantly lower than the influent concentrations (p < 0.01, n = 38. The NO3−-N load was significantly correlated with the removal rate (R2 = 0.96, p < 0.01, but the NH4+-N load was not correlated with the removal rate (R2 = 0.02, p > 0.01. The area-based constants of NO3−-N and NH4+-N at 20 °C were 27 ± 26 (mean ± SD and 14 ± 10 m∙year−1, respectively. The temperature coefficients for NO3−-N and NH4+-N were estimated at 1.004 and 0.960, respectively. The area-based constants for NO3−-N and NH4+-N were not correlated with temperature (p > 0.01. The NO3−-N area-based constant was correlated with the corresponding load (R2 = 0.96, p < 0.01. The NH4+-N area rate was correlated with DO (R2 = 0.69, p < 0.01, suggesting that the factors that influenced the N removal rate in this wetland met Liebig’s law of the minimum.

  12. A Preliminary Investigation of Wastewater Treatment Efficiency and Economic Cost of Subsurface Flow Oyster-Shell-Bedded Constructed Wetland Systems

    Directory of Open Access Journals (Sweden)

    Chia-Chuan Hsu

    2013-06-01

    Full Text Available We conducted a preliminary investigation of wastewater treatment efficiency and economic cost of the oyster-shell-bedded constructed wetlands (CWs compared to the conventional gravel-bedded CW based on field monitoring data of water quality and numerical modeling. Four study subsurface (SSF CWs were built to receive wastewater from Taipei, Taiwan. Among these sites, two are vertical wetlands, filled with bagged- (VA and scattered- (VB oyster shells, and the other two horizontal wetlands were filled with scattered-oyster shells (HA and gravels (HB. The BOD, NO3−, DO and SS treatment efficiency of VA and VB were higher than HA and HB. However, VA was determined as the best option of CW design due to its highest cost-effectiveness in term of BOD removal (only 6.56 US$/kg as compared to VB, HA and HB (10.88–25.01 US$/kg. The results confirmed that oyster shells were an effective adsorption medium in CWs. Hydraulic design and arrangement of oyster shells could be important in determining their treatment efficiency and cost-effectiveness. A dynamic model was developed to simulate substance transmissions in different treatment processes in the CWS using AQUASIM 2.1 based on the water quality data. Feasible ranges of biomedical parameters involved were determined for characterizing the importance of different biochemical treatment processes in SSF CWs. Future work will involve extending the experimental period to confirm the treatment efficiency of the oyster-shell-bedded CW systems in long-term operation and provide more field data for the simulated model instead of the literature values.

  13. Numerical modeling of experimental observations on gas formation and multi-phase flow of carbon dioxide in subsurface formations

    Science.gov (United States)

    Pawar, R.; Dash, Z.; Sakaki, T.; Plampin, M. R.; Lassen, R. N.; Illangasekare, T. H.; Zyvoloski, G.

    2011-12-01

    One of the concerns related to geologic CO2 sequestration is potential leakage of CO2 and its subsequent migration to shallow groundwater resources leading to geochemical impacts. Developing approaches to monitor CO2 migration in shallow aquifer and mitigate leakage impacts will require improving our understanding of gas phase formation and multi-phase flow subsequent to CO2 leakage in shallow aquifers. We are utilizing an integrated approach combining laboratory experiments and numerical simulations to characterize the multi-phase flow of CO2 in shallow aquifers. The laboratory experiments involve a series of highly controlled experiments in which CO2 dissolved water is injected in homogeneous and heterogeneous soil columns and tanks. The experimental results are used to study the effects of soil properties, temperature, pressure gradients and heterogeneities on gas formation and migration. We utilize the Finite Element Heat and Mass (FEHM) simulator (Zyvoloski et al, 2010) to numerically model the experimental results. The numerical models capture the physics of CO2 exsolution, multi-phase fluid flow as well as sand heterogeneity. Experimental observations of pressure, temperature and gas saturations are used to develop and constrain conceptual models for CO2 gas-phase formation and multi-phase CO2 flow in porous media. This talk will provide details of development of conceptual models based on experimental observation, development of numerical models for laboratory experiments and modelling results.

  14. Quantifying Subsurface Water and Heat Distribution and its Linkage with Landscape Properties in Terrestrial Environment using Hydro-Thermal-Geophysical Monitoring and Coupled Inverse Modeling

    Science.gov (United States)

    Dafflon, B.; Tran, A. P.; Wainwright, H. M.; Hubbard, S. S.; Peterson, J.; Ulrich, C.; Williams, K. H.

    2015-12-01

    Quantifying water and heat fluxes in the subsurface is crucial for managing water resources and for understanding the terrestrial ecosystem where hydrological properties drive a variety of biogeochemical processes across a large range of spatial and temporal scales. Here, we present the development of an advanced monitoring strategy where hydro-thermal-geophysical datasets are continuously acquired and further involved in a novel inverse modeling framework to estimate the hydraulic and thermal parameter that control heat and water dynamics in the subsurface and further influence surface processes such as evapotranspiration and vegetation growth. The measured and estimated soil properties are also used to investigate co-interaction between subsurface and surface dynamics by using above-ground aerial imaging. The value of this approach is demonstrated at two different sites, one in the polygonal shaped Arctic tundra where water and heat dynamics have a strong impact on freeze-thaw processes, vegetation and biogeochemical processes, and one in a floodplain along the Colorado River where hydrological fluxes between compartments of the system (surface, vadose zone and groundwater) drive biogeochemical transformations. Results show that the developed strategy using geophysical, point-scale and aerial measurements is successful to delineate the spatial distribution of hydrostratigraphic units having distinct physicochemical properties, to monitor and quantify in high resolution water and heat distribution and its linkage with vegetation, geomorphology and weather conditions, and to estimate hydraulic and thermal parameters for enhanced predictions of water and heat fluxes as well as evapotranspiration. Further, in the Colorado floodplain, results document the potential presence of only periodic infiltration pulses as a key hot moment controlling soil hydro and biogeochemical functioning. In the arctic, results show the strong linkage between soil water content, thermal

  15. A comparative study of five horizontal subsurface flow constructed wetlands using different plant species for domestic wastewater treatment.

    Science.gov (United States)

    Villaseñor Camacho, J; De Lucas Martínez, A; Gómez Gómez, R; Mena Sanz, J

    2007-12-01

    This project studied domestic wastewater treatment by horizontal subsurface flow (HSSF) constructed wetlands (CW) and compared the effect of four different plant species on the operating conditions, dissolved oxygen (DO), and redox potential (ORP), and their efficiency on pollutants removal. Five HSSF CWs were fed for 10 months with low loaded synthetic domestic wastewater, using theoretical hydraulic residence time of 7.6 days. The plant species under study were the following: Phragmites australis (CW1), Lythrum salicaria (CW3), Cladium mariscus (CW4) and Iris pseudacorus (CW5). CW2 was not planted and this was used as control. Qualitative measurements determined a greater growth of Lythrum salicaria and Iris pseudacorus than the others. Dissolved oxygen concentrations were very low in the entire bulk liquid of all the CWs. Also ORP values were very similar in all wetlands, dealing with facultative anaerobic environments. All planted wetlands improved pollutants removal compared with the unplanted control wetland. The performances in terms of COD, TN, TP and SO4(2-) removal obtained by the different CWs were in the ranges 80-90%, 35-55%, 15-40% and 45-60% respectively. Lythrum salicaria and Iris pseudacorus, which exhibited greater growth, were always the most efficient species that improved not only nutrients plant uptake but also other microbial removal processes probably due to a higher aeration potential, such as nitrification or aerobic respiration. Sulphate reduction was the most important mechanism for COD removal. Cladium mariscus, an autochthonous plant that grows in the south-central Iberian Peninsula, was less efficient than Lythrum salicaria and Iris pseudacorus, but improved the unplanted wetland wastewater efficiency.

  16. [Removal efficiency of C and N in micro-polluted river through a subsurface-horizontal flow constructed wetlands].

    Science.gov (United States)

    Yang, Xin-ping; Zhou, Li-xiang; Dai, Yuan-yuan; Cui, Chun-hong

    2008-08-01

    A subsurface-horizontal flow constructed wetlands (CWs) planted with reed was used to treat micro-polluted river water in this study with an aim to investigate the long-term treatment efficiency of CWs especially for organic C and N. Average data obtained from two-year plant growth season showed that performance of the wetlands appeared to be affected by both establishment/maturation factors and year-to-year climatic variations. The results displayed that the removal of C and N in the influent depended, to a certain extend, on plant growth and seasonal variations, especially for total N removal. It was observed that C removal occurred mainly in the front of CWs in the first-year's operation period and then was translocated to the rear end of wetlands in the second-year's operation period. C/N ratio in the influent was 5 or more, indicating enough C source supply for denitrification. Organic C removal efficiencies varied from 6.10% to 37.83% throughout the trial. Average total N removal efficiency of 15.51% in the first-year operation period and then declined to 8.61% in the second year. The highest removal efficiency of total N was below 40% throughout the two-year trial. It was found that nitrification and denitrification reached dynamic equilibrium at the middle of the wetlands where the highest total N removal efficiency occurred. The greatest oxygen consumption was observed in the front and middle of CWs. It was noted that nitrification occurred even in deep layer located in the rear end of the wetlands in the second-year operation period. Nitrification and denitrification occurred concurrently with C and total N removal along the stream way. Low-molecular-weight organic acids released from reed rhizosphere seemed to have a significant inhibitory effect on chemoautrophic nitrifying bacteria, which involved in nitrogen removal efficiency of the wetlands, particularly during spring and autumn.

  17. [Community Characteristics of ANAMMOX Bacteria in Subsurface Flow Constructed Wetland (SSFCW) for Processing of Aquaculture Waster Water].

    Science.gov (United States)

    Zeng, Xian-lei; Liu, Xing-guo; Wu, Zong-fan; Shi, Xu; Lu, Shi-min

    2016-02-15

    Anaerobic ammonium oxidation (ANAMMOX) is one of the important functions in waste water treatment by subsurface flow constructed wetland (SSFCW), however, there are few studies on ANAMMOX in SSFCW environment at present. The community characteristics of ANAMMOX in the SSFCW of processing aquaculture waste water were explored in this study. In order to analyze the structure, diversity and abundance of ANAMMOX bacteria, several 16S rRNA clone libraries were constructed and real-time PCR targeting specific 16S rRNA genes together with diversity analysis was adopted. The obtained results showed that the SSFCW identified a total of three unknown clusters and two known clusters including Candidatus brocadia and Candidatus kuenenia. The dominant cluster was Candidatus brocadia. The highest diversity levels of ANAMMOX bacteria occurred in autumn (H', 1.21), while the lowest in spring (H', 0.64). The abundance of ANAMMOX bacteria in SSFCW environment ranged from 8.0 x 10(4) to 9.4 x 10(6) copies x g(-1) of fresh weight and the copy number of total bacterial 16S rRNA genes ranged from 7.3 x 10(9) to 9.1 x 10(10) copies x g(-1) of fresh weight during culture cycle. There were significant differences in the ANAMMOX bacteria abundances of different stratum and seasons in SSFCW environment, but the differences in total bacterial abundances were not obvious. In addition, the differences in ANAMMOX bacteria abundances in different stratum and seasons in SSFCW environment were irregular in different culture cycle. According to the distribution characteristics of ANAMMOX bacteria in the wetland, the denitrification effect of SSFCW could be improved by changing the supplying manners of aquaculture wastewater and adjusting the structure of wetland. The research results will provide reference for further optimizing the SSFCW and improving the efficiency of purification.

  18. Effects of cattail biomass on sulfate removal and carbon sources competition in subsurface-flow constructed wetlands treating secondary effluent.

    Science.gov (United States)

    Chen, Yi; Wen, Yue; Zhou, Junwei; Tang, Zhiru; Li, Ling; Zhou, Qi; Vymazal, Jan

    2014-08-01

    Sulfate is frequently found in the influent of subsurface-flow constructed wetlands (SSF CWs) used as tertiary treatments. To reveal the effects of plants and litters on sulfate removal, as well as the competition for organic carbon among microorganisms in SSF CWs, five laboratory-scale SSF CW microcosms were set up and were operated as a batch system with HRT 5 d. The results showed that the presence of Typha latifolia had little effect on sulfate removal in CWs, with or without additional carbon sources. Cattail litter addition greatly improved sulfate removal in SSF CWs. This improvement was linked to the continuous input of labile organic carbon, which lowers the redox level and supplies a habitat for sulfate reducing bacteria (SRB). The presence of SRB in cattail litter indicated the possibility of sulfate removal around the carbon supplier, but the quantity of microbes in cattail litter was much lower than that in gravel. Stoichiometry calculations showed that the contribution of SRB to COD removal (21-26%) was less than that of methane-producing bacteria (MPB) (47-61%) during the initial stage but dominated COD removal (42-65%) during the terminal stage. The contributions of aerobic bacteria (AB) and denitrification bacteria (DB) to COD removal were always lower than that of SRB. It was also observed that the variations in COD: S ratio had a great influence on the relative abundance of genes between SRB and MPB and both of them could be used as good predictors of carbon competition between SRB and MPB in CWs.

  19. Trajectory piecewise quadratic reduced-order model for subsurface flow, with application to PDE-constrained optimization

    Science.gov (United States)

    Trehan, Sumeet; Durlofsky, Louis J.

    2016-12-01

    A new reduced-order model based on trajectory piecewise quadratic (TPWQ) approximations and proper orthogonal decomposition (POD) is introduced and applied for subsurface oil-water flow simulation. The method extends existing techniques based on trajectory piecewise linear (TPWL) approximations by incorporating second-derivative terms into the reduced-order treatment. Both the linear and quadratic reduced-order methods, referred to as POD-TPWL and POD-TPWQ, entail the representation of new solutions as expansions around previously simulated high-fidelity (full-order) training solutions, along with POD-based projection into a low-dimensional space. POD-TPWQ entails significantly more offline preprocessing than POD-TPWL as it requires generating and projecting several third-order (Hessian-type) terms. The POD-TPWQ method is implemented for two-dimensional systems. Extensive numerical results demonstrate that it provides consistently better accuracy than POD-TPWL, with speedups of about two orders of magnitude relative to high-fidelity simulations for the problems considered. We demonstrate that POD-TPWQ can be used as an error estimator for POD-TPWL, which motivates the development of a trust-region-based optimization framework. This procedure uses POD-TPWL for fast function evaluations and a POD-TPWQ error estimator to determine when retraining, which entails a high-fidelity simulation, is required. Optimization results for an oil-water problem demonstrate the substantial speedups that can be achieved relative to optimizations based on high-fidelity simulation.

  20. Network Traffic Anomalies Detection and Identification with Flow Monitoring

    CERN Document Server

    Nguyen, Huy; Kim, Dong Il; Choi, Deokjai

    2010-01-01

    Network management and security is currently one of the most vibrant research areas, among which, research on detecting and identifying anomalies has attracted a lot of interest. Researchers are still struggling to find an effective and lightweight method for anomaly detection purpose. In this paper, we propose a simple, robust method that detects network anomalous traffic data based on flow monitoring. Our method works based on monitoring the four predefined metrics that capture the flow statistics of the network. In order to prove the power of the new method, we did build an application that detects network anomalies using our method. And the result of the experiments proves that by using the four simple metrics from the flow data, we do not only effectively detect but can also identify the network traffic anomalies.

  1. Emerging organic contaminant removal depending on primary treatment and operational strategy in horizontal subsurface flow constructed wetlands: influence of redox.

    Science.gov (United States)

    Avila, Cristina; Reyes, Carolina; Bayona, Josep María; García, Joan

    2013-01-01

    This study aimed at assessing the influence of primary treatment (hydrolytic upflow sludge blanket (HUSB) reactor vs. conventional settling) and operational strategy (alternation of saturated/unsaturated phases vs. permanently saturated) on the removal of various emerging organic contaminants (i.e. ibuprofen, diclofenac, acetaminophen, tonalide, oxybenzone, bisphenol A) in horizontal subsurface flow constructed wetlands. For that purpose, a continuous injection experiment was carried out in an experimental treatment plant for 26 days. The plant had 3 treatment lines: a control line (settler-wetland permanently saturated), a batch line (settler-wetland operated with saturate/unsaturated phases) and an anaerobic line (HUSB reactor-wetland permanently saturated). In each line, wetlands had a surface area of 2.95 m(2), a water depth of 25 cm and a granular medium D(60) = 7.3 mm, and were planted with common reed. During the study period the wetlands were operated at a hydraulic and organic load of 25 mm/d and about 4.7 g BOD/m(2)d, respectively. The injection experiment delivered very robust results that show how the occurrence of higher redox potentials within the wetland bed promotes the elimination of conventional quality parameters as well as emerging microcontaminants. Overall, removal efficiencies were always greater for the batch line than for the control and anaerobic lines, and to this respect statistically significantly differences were found for ibuprofen, diclofenac, oxybenzone and bisphenol A. As an example, ibuprofen, whose major removal mechanism has been reported to be biodegradation under aerobic conditions, showed a higher removal in the batch line (85%) than in the control (63%) and anaerobic (52%) lines. Bisphenol A showed also a great dependence on the redox status of the wetlands, finding an 89% removal rate for the batch line, as opposed to the control and anaerobic lines (79 and 65%, respectively). Furthermore, diclofenac showed a greater

  2. Analyzing subsurface drain network performance in an agricultural monitoring site with a three-dimensional hydrological model

    Science.gov (United States)

    Nousiainen, Riikka; Warsta, Lassi; Turunen, Mika; Huitu, Hanna; Koivusalo, Harri; Pesonen, Liisa

    2015-10-01

    Effectiveness of a subsurface drainage system decreases with time, leading to a need to restore the drainage efficiency by installing new drain pipes in problem areas. The drainage performance of the resulting system varies spatially and complicates runoff and nutrient load generation within the fields. We presented a method to estimate the drainage performance of a heterogeneous subsurface drainage system by simulating the area with the three-dimensional hydrological FLUSH model. A GIS analysis was used to delineate the surface runoff contributing area in the field. We applied the method to reproduce the water balance and to investigate the effectiveness of a subsurface drainage network of a clayey field located in southern Finland. The subsurface drainage system was originally installed in the area in 1971 and the drainage efficiency was improved in 1995 and 2005 by installing new drains. FLUSH was calibrated against total runoff and drain discharge data from 2010 to 2011 and validated against total runoff in 2012. The model supported quantification of runoff fractions via the three installed drainage networks. Model realisations were produced to investigate the extent of the runoff contributing areas and the effect of the drainage parameters on subsurface drain discharge. The analysis showed that better model performance was achieved when the efficiency of the oldest drainage network (installed in 1971) was decreased. Our analysis method can reveal the drainage system performance but not the reason for the deterioration of the drainage performance. Tillage layer runoff from the field was originally computed by subtracting drain discharge from the total runoff. The drains installed in 1995 bypass the measurement system, which renders the tillage layer runoff calculation procedure invalid after 1995. Therefore, this article suggests use of a local correction coefficient based on the simulations for further research utilizing data from the study area.

  3. Discrete Fracture Network Modeling and Simulation of Subsurface Transport for the Topopah Springs and Lava Flow Aquifers at Pahute Mesa, FY 15 Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kwicklis, Edward Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Birdsell, Kay Hanson [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Harrod, Jeremy Ashcraft [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-10-18

    This progress report for fiscal year 2015 (FY15) describes the development of discrete fracture network (DFN) models for Pahute Mesa. DFN models will be used to upscale parameters for simulations of subsurface flow and transport in fractured media in Pahute Mesa. The research focuses on modeling of groundwater flow and contaminant transport using DFNs generated according to fracture characteristics observed in the Topopah Spring Aquifer (TSA) and the Lava Flow Aquifer (LFA). This work will improve the representation of radionuclide transport processes in large-scale, regulatory-focused models with a view to reduce pessimistic bounding approximations and provide more realistic contaminant boundary calculations that can be used to describe the future extent of contaminated groundwater. Our goal is to refine a modeling approach that can translate parameters to larger-scale models that account for local-scale flow and transport processes, which tend to attenuate migration.

  4. Application of a fully integrated surface-subsurface physically based flow model for evaluating groundwater recharge from a flash flood event

    Science.gov (United States)

    Pino, Cristian; Herrera, Paulo; Therrien, René

    2017-04-01

    In many arid regions around the world groundwater recharge occurs during flash floods. This transient spatially and temporally concentrated flood-recharge process takes place through the variably saturated zone between surface and usually the deep groundwater table. These flood events are characterized by rapid and extreme changes in surface flow depth and velocity and soil moisture conditions. Infiltration rates change over time controlled by the hydraulic gradients and the unsaturated hydraulic conductivity at the surface-subsurface interface. Today is a challenge to assess the spatial and temporal distribution of groundwater recharge from flash flood events under real field conditions at different scales in arid areas. We apply an integrated surface-subsurface variably saturated physically-based flow model at the watershed scale to assess the recharge process during and after a flash flood event registered in an arid fluvial valley in Northern Chile. We are able to reproduce reasonably well observed groundwater levels and surface flow discharges during and after the flood with a calibrated model. We also investigate the magnitude and spatio-temporal distribution of recharge and the response of the system to variations of different surface and subsurface parameters, initial soil moisture content and groundwater table depths and surface flow conditions. We demonstrate how an integrated physically based model allows the exploration of different spatial and temporal system states, and that the analysis of the results of the simulations help us to improve our understanding of the recharge processes in similar type of systems that are common to many arid areas around the world.

  5. Key design factors affecting microbial community composition and pathogenic organism removal in horizontal subsurface flow constructed wetlands.

    Science.gov (United States)

    Morató, Jordi; Codony, Francesc; Sánchez, Olga; Pérez, Leonardo Martín; García, Joan; Mas, Jordi

    2014-05-15

    Constructed wetlands constitute an interesting option for wastewater reuse since high concentrations of contaminants and pathogenic microorganisms can be removed with these natural treatment systems. In this work, the role of key design factors which could affect microbial removal and wetland performance, such as granular media, water depth and season effect was evaluated in a pilot system consisting of eight parallel horizontal subsurface flow (HSSF) constructed wetlands treating urban wastewater from Les Franqueses del Vallès (Barcelona, Spain). Gravel biofilm as well as influent and effluent water samples of these systems were taken in order to detect the presence of bacterial indicators such as total coliforms (TC), Escherichia coli, fecal enterococci (FE), Clostridium perfringens, and other microbial groups such as Pseudomonas and Aeromonas. The overall microbial inactivation ratio ranged between 1.4 and 2.9 log-units for heterotrophic plate counts (HPC), from 1.2 to 2.2 log units for total coliforms (TC) and from 1.4 to 2.3 log units for E. coli. The presence of fine granulometry strongly influenced the removal of all the bacterial groups analyzed. This effect was significant for TC (p=0.009), E. coli (p=0.004), and FE (p=0.012). Shallow HSSF constructed wetlands were more effective for removing Clostridium spores (p=0.039), and were also more efficient for removing TC (p=0.011) and E. coli (p=0.013) when fine granulometry was used. On the other hand, changes in the total bacterial community from gravel biofilm were examined by using denaturing gradient gel electrophoresis (DGGE) and sequencing of polymerase chain reaction (PCR)-amplified fragments of the 16S rRNA gene recovered from DGGE bands. Cluster analysis of the DGGE banding pattern from the different wetlands showed that microbial assemblages separated according to water depth, and sequences of different phylogenetic groups, such as Alpha, Beta and Delta-Proteobacteria, Nitrospirae, Bacteroidetes

  6. Greenhouse wastewater treatment by baffled subsurface-flow constructed wetlands supplemented with flower straws as carbon source in different modes.

    Science.gov (United States)

    Chang, Junjun; Ma, Luyao; Chen, Jinquan; Lu, Yifeng; Wang, Xiaoyun

    2017-01-01

    Four laboratory-scale baffled subsurface-flow constructed wetlands (BSCWs) were established for the treatment of greenhouse wastewater containing high levels of nitrate and sulfate in the present study. Each BSCW microcosm involved a treatment zone and another post-treatment zone with a surface area ratio of 2:1. Evenly mixed straws of carnation and rose (w/w: 1/1), two common ornamental flowers, were supplemented as an organic carbon source into the treatment zone through a hydrolysis zone (CW 1), decentralized vertically installed perforated pipes (CW 2), and centralized pipes (CW 3 in the figures), except the blank system. Removals and transformations of nitrogen and sulfate as well as carbon release in the BSCWs were investigated and comparatively assessed. Results showed that the supplements of flower straws could greatly enhance both the nitrate and sulfate removals, and good performance was achieved during the beginning operation period of 30 days, followed by decline due to insufficient organic carbon supply. Nitrate removal efficiency was significantly higher and more stable compared to sulfate. The highest removal rates of nitrate and sulfate were achieved in the CW 3, with a mean value of 4.33 g NO3(-)-N·m(-2) d(-1) and 2.74 g SO4(2-)-S·m(-2) d(-1), respectively, although the differences among the experimental microcosms were not statistically significant. However, almost the same TN removal rate (3.40-3.47 g N·m(-2) d(-1)) was obtained due to the productions of NO2(-)-N and NH4(+)-N and leaching of organic N from the straws. High contents of organic carbon and colored substance were leached from the straws during the initial 10 days, but dropped rapidly to low levels, and could hardly determined after 30 days operation. The post-treatment zone could further eliminate various contaminants, but the capability was limited. Inorganic carbon (IC) concentration was detected to be a highly good indicator for the estimation of nitrate and sulfate

  7. Solution for Monitoring the Flows through Web Dynpro ABAP Interfaces

    Directory of Open Access Journals (Sweden)

    Mihaela Osaci

    2015-12-01

    Full Text Available The paper presents a monitoring solution for flow measurement through Web Dynpro ABAP interface. The use of integrated software systems in companies currently represents an essential condition for providing higher and more reliable access to information resources. The SAP Netweaver, a multilingual & multitasking system based on the three-tier client-server technology, is one of the mostly used integrated platforms implemented in companies.

  8. Flow-accelerated corrosion monitoring through advanced sensors

    Science.gov (United States)

    Kim, Jung T.; Seong, Seung H.; Lee, Cheol K.; Hur, Sub; Lee, Na Y.; Lee, Sang J.

    2005-02-01

    In order to successfully implement the extended-life operation plan of the nuclear power plant (NPP), predictive maintenance based on on-line monitoring of deteriorated components becomes highly important. Pipe wall-thinning is usually caused by Flow-Accelerated Corrosion (FAC) under the undesirable combination of water chemistry, flow velocity and material composition. In order to increase the confidence of understanding on underlying process, a multi-disciplinary approach has been adopted in this work. Here, we apply a combination of several advanced sensors, ranging from chemical electrodes to mechanical vibration sensors to monitor the thickness change of the elbow, which can be still economical option. Electrochemical Corrosion Potential (ECP) and pH are chosen as electrochemical parameters, the change of vibration mode, displacement, and etc. are chosen as mechanical parameters to monitor the wall thinning phenomena. Electrodes are developed for the on-line monitoring of pH and ECP. Vibration is considered as a promising candidate as a mechanical parameter. Various sensors are surveyed and some are chosen based on FEM analysis result, which shows the approximate vibration range according to the thickness change. Mechanical sensors need to be sensitive enough to detect small thickness change with adequate safety margin to a pipe rupture. A few sensors are suggested to detect vibration or displacement quantitatively. Fiber optic sensors are chosen for their non-contacting property, which is appropriate for the high temperature application. Accelerometer and capacitance gage are suggested for their applicability fit to the test purpose.

  9. Monitoring blood flow and photobleaching during topical ALA PDT treatment

    Science.gov (United States)

    Sands, Theresa L.; Sunar, Ulas; Foster, Thomas H.; Oseroff, Allan R.

    2009-02-01

    Photodynamic therapy (PDT) using topical aminolevulinic acid (ALA) is currently used as a clinical treatment for nonmelanoma skin cancers. In order to optimize PDT treatment, vascular shutdown early in treatment must be identified and prevented. This is especially important for topical ALA PDT where vascular shutdown is only temporary and is not a primary method of cell death. Shutdown in vasculature would limit the delivery of oxygen which is necessary for effective PDT treatment. Diffuse correlation spectroscopy (DCS) was used to monitor relative blood flow changes in Balb/C mice undergoing PDT at fluence rates of 10mW/cm2 and 75mW/cm2 for colon-26 tumors implanted intradermally. DCS is a preferable method to monitor the blood flow during PDT of lesions due to its ability to be used noninvasively throughout treatment, returning data from differing depths of tissue. Photobleaching of the photosensitizer was also monitored during treatment as an indirect manner of monitoring singlet oxygen production. In this paper, we show the conditions that cause vascular shutdown in our tumor model and its effects on the photobleaching rate.

  10. Monitoring of multiphase flows for superconducting accelerators and others applications

    Science.gov (United States)

    Filippov, Yu. P.; Kakorin, I. D.; Kovrizhnykh, A. M.; Miklayev, V. M.

    2017-07-01

    This paper is a review on implementation of measuring systems for two-phase helium, hydrogen, liquefied natural gas (LNG), and oil-formation/salty water flows. Two types of such systems are presented. The first type is based on two-phase flow-meters combining void fraction radio-frequency (RF) sensors and narrowing devices. They can be applied for superconducting accelerators cooled with two-phase helium, refueling hydrogen system for space ships and some applications in oil production industry. The second one is based on combination of a gamma-densitometer and a narrowing device. These systems can be used to monitor large two-phase LNG and oil-formation water flows. An electronics system based on a modular industrial computer is described as well. The metrological characteristics for different flow-meters are presented and the obtained results are discussed. It is also shown that the experience gained allows separationless flow-meter for three-phase oil-gas-formation water flows to be produced.

  11. An information theory application to improve understanding of subsurface flow and transport conditions at the BARC OPE3 site

    Science.gov (United States)

    Improving understanding of subsurface conditions includes comparison and discrimination of concurrent models. Additional observations can be useful for that purpose. The objective of this work was to implement and test a novel method for optimization of selecting locations for additional observation...

  12. SUBSURFACE EMPLACEMENT TRANSPORTATION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    T. Wilson; R. Novotny

    1999-11-22

    The objective of this analysis is to identify issues and criteria that apply to the design of the Subsurface Emplacement Transportation System (SET). The SET consists of the track used by the waste package handling equipment, the conductors and related equipment used to supply electrical power to that equipment, and the instrumentation and controls used to monitor and operate those track and power supply systems. Major considerations of this analysis include: (1) Operational life of the SET; (2) Geometric constraints on the track layout; (3) Operating loads on the track; (4) Environmentally induced loads on the track; (5) Power supply (electrification) requirements; and (6) Instrumentation and control requirements. This analysis will provide the basis for development of the system description document (SDD) for the SET. This analysis also defines the interfaces that need to be considered in the design of the SET. These interfaces include, but are not limited to, the following: (1) Waste handling building; (2) Monitored Geologic Repository (MGR) surface site layout; (3) Waste Emplacement System (WES); (4) Waste Retrieval System (WRS); (5) Ground Control System (GCS); (6) Ex-Container System (XCS); (7) Subsurface Electrical Distribution System (SED); (8) MGR Operations Monitoring and Control System (OMC); (9) Subsurface Facility System (SFS); (10) Subsurface Fire Protection System (SFR); (11) Performance Confirmation Emplacement Drift Monitoring System (PCM); and (12) Backfill Emplacement System (BES).

  13. Characterization of recharge and flow behaviour of different water sources in Gunung Kidul and its impact on water quality based on hydrochemical and physico-chemical monitoring

    Science.gov (United States)

    Eiche, Elisabeth; Hochschild, Maren; Haryono, Eko; Neumann, Thomas

    2016-09-01

    Karst aquifers are important water resources but highly vulnerable due to their heterogeneous and complex characteristics. Various hydrological aspects (recharge, flow behaviour) have to be known in detail to develop a sustainable concept for water collection, distribution and treatment. In the karst area of Gunung Sewu (Java, Indonesia) such a concept was to be implemented within a German-Indonesian joint IWRM project. The basic hydrogeological conditions and water quality aspects were characterized on a regional scale through hydrochemical monitoring of springs, wells, subsurface and surface rivers. More detailed information about the recharge, flow and storage behaviour was obtained from high resolution monitoring of T, EC and discharge in one large underground river system. The water quality is well below any guideline values with regard to inorganic pollutants during dry season. During rainy season, dissolved Al concentrations are frequently above the Indonesian guideline value. Slow matrix flow is the most important recharge component during dry season, thus assuring the year-round water availability in the subsurface karst. During rainy season, quick infiltration of the surface water is a dominant recharge component. Rapid response of discharge, T and EC to heavy rain suggests the presence of point recharge that feeds a highly karstfied conduit system with fast conduit flow and short transit time of water. The strong variations in discharge and hydrochemistry are particularly challenging for technical water usage and treatment facilities. Piston flow is indicated to be the third important flow component and is induced by heavy rainfall.

  14. Monitoring subsurface coal fires in Jharia coalfield using observations of land subsidence from differential interferometric synthetic aperture radar (DInSAR)

    Indian Academy of Sciences (India)

    Nishant Gupta; Tajdarul H Syed; Ashiihrii Athiphro

    2013-10-01

    Coal fires in the Jharia coalfield pose a serious threat to India’s vital resource of primary coking coal and the regional environment. In order to undertake effective preventative measures, it is critical to detect the occurrence of subsurface coal fires and to monitor the extent of the existing ones. In this study, Differential Interferometric Synthetic Aperature Radar (DInSAR) technique has been utilized to monitor subsurface coal fires in the Jharia coalfield. Results showed that majority of the coal fire-related subsidence were concentrated on the eastern and western boundaries of the coalfield. The magnitude of subsidence observed was classified into high (10–27.8 mm), low (0–10 mm) and upliftment (−10–0 mm). The results were strongly supported by in situ observations and satellite-based thermal imagery analysis. Major subsidence was observed in the areas with repeated sightings of coal fire. Further, the study highlighted on the capability of the methodology for predicting potential coal fire zones on the basis of land surface subsidence only. The results from this study have major implications for demarcating the hazardous coal fire areas as well as effective implementation of public safety measures.

  15. Monitoring subsurface coal fires in Jharia coalfield using observations of land subsidence from differential interferometric synthetic aperture radar (DInSAR)

    Science.gov (United States)

    Gupta, Nishant; Syed, Tajdarul H.; Athiphro, Ashiihrii

    2013-10-01

    Coal fires in the Jharia coalfield pose a serious threat to India's vital resource of primary coking coal and the regional environment. In order to undertake effective preventative measures, it is critical to detect the occurrence of subsurface coal fires and to monitor the extent of the existing ones. In this study, Differential Interferometric Synthetic Aperature Radar (DInSAR) technique has been utilized to monitor subsurface coal fires in the Jharia coalfield. Results showed that majority of the coal fire-related subsidence were concentrated on the eastern and western boundaries of the coalfield. The magnitude of subsidence observed was classified into high (10-27.8 mm), low (0-10 mm) and upliftment (-10-0 mm). The results were strongly supported by in situ observations and satellite-based thermal imagery analysis. Major subsidence was observed in the areas with repeated sightings of coal fire. Further, the study highlighted on the capability of the methodology for predicting potential coal fire zones on the basis of land surface subsidence only. The results from this study have major implications for demarcating the hazardous coal fire areas as well as effective implementation of public safety measures.

  16. A flux monitoring method for easy and accurate flow rate measurement in pressure-driven flows.

    Science.gov (United States)

    Siria, Alessandro; Biance, Anne-Laure; Ybert, Christophe; Bocquet, Lydéric

    2012-03-07

    We propose a low-cost and versatile method to measure flow rate in microfluidic channels under pressure-driven flows, thereby providing a simple characterization of the hydrodynamic permeability of the system. The technique is inspired by the current monitoring method usually employed to characterize electro-osmotic flows, and makes use of the measurement of the time-dependent electric resistance inside the channel associated with a moving salt front. We have successfully tested the method in a micrometer-size channel, as well as in a complex microfluidic channel with a varying cross-section, demonstrating its ability in detecting internal shape variations.

  17. Behaviour of the biochemical demand for oxygen in wetlands with horizontal subsurface flow; Comportamiento de la demanda bioquimica de oxigeno en humedales con flujo subsuperficial horizontal

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Diaz, O.; Hernandez Marrero, J. [Centro de Investigaciones Hidraulicas. La Habana. Cuba (Cuba); Rodriguez Pastor, M.; Prats Rico, D. [Universidad de Alicante (Spain)

    2000-07-01

    The conventional wastewater treatments are expensive and required high-energy consumption. Those systems in most of the cases do not eliminate nutrients like nitrogen and phosphorous, principals agents for eutrophication in water bodies. As an alternative of conventional treatment in recent years has been develop techniques, based on the natural mechanism, those system required the same amount of energy that the conventional system, but this energy is take from the nature. The objective of the present work is to study the subsurface horizontal flow wetland and it is ability to reduce the organic loading rate expressed as BOD5 in Cuban conditions, using different emergent plants species. (Author) 29 refs.

  18. Monitoring individual traffic flows within the ATLAS TDAQ network

    Energy Technology Data Exchange (ETDEWEB)

    Sjoen, R; Batraneanu, S M; Leahu, L; Martin, B; Al-Shabibi, A [CERN, 1211 Geneva 23 (Switzerland); Stancu, S; Ciobotaru, M, E-mail: rune.velle.sjoen@cern.c [' Politehnica' University of Bucharest (Romania)

    2010-04-01

    The ATLAS data acquisition system consists of four different networks interconnecting up to 2000 processors using up to 200 edge switches and five multi-blade chassis devices. The architecture of the system has been described in [1] and its operational model in [2]. Classical, SNMP-based, network monitoring provides statistics on aggregate traffic, but for performance monitoring and troubleshooting purposes there was an imperative need to identify and quantify single traffic flows. sFlow [3] is an industry standard based on statistical sampling which attempts to provide a solution to this. Due to the size of the ATLAS network, the collection and analysis of the sFlow data from all devices generates a data handling problem of its own. This paper describes how this problem is addressed by making it possible to collect and store data either centrally or distributed according to need. The methods used to present the results in a relevant fashion for system analysts are discussed and we explore the possibilities and limitations of this diagnostic tool, giving an example of its use in solving system problems that arise during the ATLAS data taking.

  19. Monitoring individual traffic flows within the ATLAS TDAQ network

    CERN Document Server

    Sjoen, R; Ciobotaru, M; Batraneanu, S M; Leahu, L; Martin, B; Al-Shabibi, A

    2010-01-01

    The ATLAS data acquisition system consists of four different networks interconnecting up to 2000 processors using up to 200 edge switches and five multi-blade chassis devices. The architecture of the system has been described in [1] and its operational model in [2]. Classical, SNMP-based, network monitoring provides statistics on aggregate traffic, but for performance monitoring and troubleshooting purposes there was an imperative need to identify and quantify single traffic flows. sFlow [3] is an industry standard based on statistical sampling which attempts to provide a solution to this. Due to the size of the ATLAS network, the collection and analysis of the sFlow data from all devices generates a data handling problem of its own. This paper describes how this problem is addressed by making it possible to collect and store data either centrally or distributed according to need. The methods used to present the results in a relevant fashion for system analysts are discussed and we explore the possibilities a...

  20. Modeling organic matter and nitrogen removal from domestic wastewater in a pilot-scale vertical subsurface flow constructed wetland.

    Science.gov (United States)

    Bustillo-Lecompte, Ciro Fernando; Mehrvar, Mehrab; Quiñones-Bolaños, Edgar; Castro-Faccetti, Claudia Fernanda

    2016-01-01

    Constructed wetlands have become an attractive alternative for wastewater treatment. However, there is not a globally accepted mathematical model to predict their performance. In this study, the VS2DTI software was used to predict the effluent biochemical oxygen demand (BOD) and total nitrogen (TN) in a pilot-scale vertical flow constructed wetland (VFCW) treating domestic wastewater. After a 5-week adaptation period, the pilot system was monitored for another 6 weeks. Experiments were conducted at hydraulic retention times (HRTs) in the range of 2-4 days with Typha latifolia as the vegetation. The raw wastewater concentrations ranged between 144-430 and 122-283 mg L(-1) for BOD5 and TN, respectively. A first-order kinetic model coupled with the advection/dispersion and Richards' equations was proposed to predict the removal rates of BOD5 and TN from domestic wastewater. Two main physical processes were modeled in this study, porous material water flow and solute transport through the different layers of the VFCW to simulate the constructed wetland (CW) conditions. The model was calibrated based on the BOD5 and TN degradation constants. The model indicated that most of BOD and TN (88 and 92%, respectively) were removed through biological activity followed by adsorption. It was also observed that the evapotranspiration was seen to have a smaller impact. An additional data series of effluent BOD and TN was used for model validation. The residual analysis of the calibrated model showed a relatively random pattern, indicating a decent fit. Thus, the VS2DTI was found to be a useful tool for CW simulation.

  1. A multichannel bioimpedance monitor for full-body blood flow monitoring.

    Science.gov (United States)

    Vondra, Vlastimil; Jurak, Pavel; Viscor, Ivo; Halamek, Josef; Leinveber, Pavel; Matejkova, Magdalena; Soukup, Ladislav

    2016-02-01

    The design, properties, and possible diagnostic contribution of a multichannel bioimpedance monitor (MBM) with three independent current sources are presented in this paper. The simultaneous measurement of bioimpedance at 18 locations (the main part of the body, legs, arms, and neck) provides completely new information, on the basis of which more precise haemodynamic parameters can be obtained. The application of the MBM during various haemodynamic stages, such as resting in a supine position, tilting, exercise stress, and various respiration manoeuvres, is demonstrated. Statistical analysis on a group of 34 healthy volunteers is presented for demonstration of blood flow monitoring by using the proposed method.

  2. Long-term flow monitoring of submarine gas emanations

    Science.gov (United States)

    Spickenbom, K.; Faber, E.; Poggenburg, J.; Seeger, C.

    2009-04-01

    One of the Carbon Capture and Storage (CCS) strategies currently under study is the sequestration of CO2 in sub-seabed geological formations. Even after a thorough review of the geological setting, there is the possibility of leaks from the reservoirs. As part of the EU-financed project CO2ReMoVe (Research, Monitoring, Verification), which aims to develop innovative research and technologies for monitoring and verification of carbon dioxide geological storage, we are working on the development of submarine long-term gas flow monitoring systems. Technically, however, these systems are not limited to CO2 but can be used for monitoring of any free gas emission (bubbles) on the seafloor. The basic design of the gas flow sensor system was derived from former prototypes developed for monitoring CO2 and CH4 on mud volcanoes in Azerbaijan. This design was composed of a raft floating on the surface above the gas vent to collect the bubbles. Sensors for CO2 flux and concentration and electronics for data storage and transmission were mounted on the raft, together with battery-buffered solar panels for power supply. The system was modified for installation in open sea by using a buoy instead of a raft and a funnel on the seafloor to collect the gas, which is then guided above water level through a flexible tube. Besides some technical problems (condensed water in the tube, movement of the buoys due to waves leading to biased measurement of flow rates), this setup provides a cost-effective solution for shallow waters. However, a buoy interferes with ship traffic, and it is also difficult to adapt this design to greater water depths. These requirements can best be complied by a completely submersed system. To allow unattended long-term monitoring in a submarine environment, such a system has to be extremely durable. Therefore, we focussed on developing a mechanically and electrically as simple setup as possible, which has the additional advantage of low cost. The system

  3. Subsurface Contamination Control

    Energy Technology Data Exchange (ETDEWEB)

    Y. Yuan

    2001-11-16

    subsurface repository; (2) provides a table of derived LRCL for nuclides of radiological importance; (3) Provides an as low as is reasonably achievable (ALARA) evaluation of the derived LRCL by comparing potential onsite and offsite doses to documented ALARA requirements; (4) Provides a method for estimating potential releases from a defective WP; (5) Provides an evaluation of potential radioactive releases from a defective WP that may become airborne and result in contamination of the subsurface facility; and (6) Provides a preliminary analysis of the detectability of a potential WP leak to support the design of an airborne release monitoring system.

  4. Subsurface Contamination Control

    Energy Technology Data Exchange (ETDEWEB)

    Y. Yuan

    2001-12-12

    subsurface repository; (2) provides a table of derived LRCL for nuclides of radiological importance; (3) Provides an as low as is reasonably achievable (ALARA) evaluation of the derived LRCL by comparing potential onsite and offsite doses to documented ALARA requirements; (4) Provides a method for estimating potential releases from a defective WP; (5) Provides an evaluation of potential radioactive releases from a defective WP that may become airborne and result in contamination of the subsurface facility; and (6) Provides a preliminary analysis of the detectability of a potential WP leak to support the design of an airborne release monitoring system.

  5. Testing a simple and low-cost method for long-term (baseline) CO2 monitoring in the shallow subsurface

    NARCIS (Netherlands)

    Gaasbeek, H.; Goldberg, T.; Koenen, M.; Visser, W.; Wildenborg, T.; Steeghs, P.

    2014-01-01

    Implementation of geological CO2 storage requires monitoring for potential leakage, with an essential part being establishment of baseline CO2 in soil gas. CO2 concentrations and weather parameters were monitored for ∼2 years at three locations in the Netherlands. CO2 concentrations in soil ranged f

  6. Testing a simple and low-cost method for long-term (baseline) CO2 monitoring in the shallow subsurface

    NARCIS (Netherlands)

    Gaasbeek, H.; Goldberg, T.; Koenen, M.; Visser, W.; Wildenborg, T.; Steeghs, P.

    2014-01-01

    Implementation of geological CO2 storage requires monitoring for potential leakage, with an essential part being establishment of baseline CO2 in soil gas. CO2 concentrations and weather parameters were monitored for ∼2 years at three locations in the Netherlands. CO2 concentrations in soil ranged f

  7. Study of the development of high resolution sub-surface fluid monitoring system using Accurately Controlled Routine Operated Seismic Sources (ACROSS); Seimitsu seigyo shingen ni yoru chika ryutai koseido monitoring no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Kumazawa, M.; Ogawa, K.; Fujii, N.; Yamaoka, K.; Kumagai, H.; Takei, Y. [Nagoya University, Nagoya (Japan). Faculty of Science; Ishihara, K.; Nakaya, m. [New Energy and Industrial Technology Development Organization, Tokyo, (Japan)

    1997-02-01

    Fourier seismology capable of determining quantities related to elastic wave velocity dispersibility and non-elastic damping is under development, and studies are under way for the development of a sub-surface probing technology utilizing this seismology. It is deemed that the above-said quantities are related to the occurrence of earthquakes, behavior of sub-surface water, and migration of magma. In this method, precisely controlled sinusoidal waves are radiated and the received spectral data is subjected to cepstrum analysis, advantageous over other methods in that it achieves a high S/N ratio in a non-destructive way, facilitates deep structure analysis, and capable of monitoring changes with the elapse of time in such a structure. A newly-developed high-mobility transportable quake generator is described, which covers a wider frequency range and aims at the short-distance exploration of sub-surface conditions. Important components of the quake generator include an eccentric mass bearing capable of dealing with high-speed rotation enabling high frequency oscillation, variable mechanism for the primary moment of inertia, exciter and ground surface coupler allowing operations on a soft ground, and torque cancelling mechanism for the excitation of SH waves only. 3 figs.

  8. The Effect of Subsurface Parameterizations on Modeled Flows in the Catchment Land Surface Model, Fortuna 2.5

    Science.gov (United States)

    Roningen, J. M.; Eylander, J. B.

    2014-12-01

    Groundwater use and management is subject to economic, legal, technical, and informational constraints and incentives at a variety of spatial and temporal scales. Planned and de facto management practices influenced by tax structures, legal frameworks, and agricultural and trade policies that vary at the country scale may have medium- and long-term effects on the ability of a region to support current and projected agricultural and industrial development. USACE is working to explore and develop global-scale, physically-based frameworks to serve as a baseline for hydrologic policy comparisons and consequence assessment, and such frameworks must include a reasonable representation of groundwater systems. To this end, we demonstrate the effects of different subsurface parameterizations, scaling, and meteorological forcings on surface and subsurface components of the Catchment Land Surface Model Fortuna v2.5 (Koster et al. 2000). We use the Land Information System 7 (Kumar et al. 2006) to process model runs using meteorological components of the Air Force Weather Agency's AGRMET forcing data from 2006 through 2011. Seasonal patterns and trends are examined in areas of the Upper Nile basin, northern China, and the Mississippi Valley. We also discuss the relevance of the model's representation of the catchment deficit with respect to local hydrogeologic structures.

  9. A Finite Difference, Semi-implicit, Equation-of-State Efficient Algorithm for the Compositional Flow Modeling in the Subsurface: Numerical Examples

    KAUST Repository

    Saavedra, Sebastian

    2012-07-01

    The mathematical model that has been recognized to have the more accurate approximation to the physical laws govern subsurface hydrocarbon flow in reservoirs is the Compositional Model. The features of this model are adequate to describe not only the performance of a multiphase system but also to represent the transport of chemical species in a porous medium. Its importance relies not only on its current relevance to simulate petroleum extraction processes, such as, Primary, Secondary, and Enhanced Oil Recovery Process (EOR) processes but also, in the recent years, carbon dioxide (CO2) sequestration. The purpose of this study is to investigate the subsurface compositional flow under isothermal conditions for several oil well cases. While simultaneously addressing computational implementation finesses to contribute to the efficiency of the algorithm. This study provides the theoretical framework and computational implementation subtleties of an IMplicit Pressure Explicit Composition (IMPEC)-Volume-balance (VB), two-phase, equation-of-state, approach to model isothermal compositional flow based on the finite difference scheme. The developed model neglects capillary effects and diffusion. From the phase equilibrium premise, the model accounts for volumetric performances of the phases, compressibility of the phases, and composition-dependent viscosities. The Equation of State (EoS) employed to approximate the hydrocarbons behaviour is the Peng Robinson Equation of State (PR-EOS). Various numerical examples were simulated. The numerical results captured the complex physics involved, i.e., compositional, gravitational, phase-splitting, viscosity and relative permeability effects. Regarding the numerical scheme, a phase-volumetric-flux estimation eases the calculation of phase velocities by naturally fitting to phase-upstream-upwinding. And contributes to a faster computation and an efficient programming development.

  10. Final Report Real Time Monitoring of Rates of Subsurface Microbial Activity Associated with Natural Attenuation and Electron Donor Availability

    Energy Technology Data Exchange (ETDEWEB)

    Lovley, Derek R. [Univ. of Massachusetts, Amherst, MA (United States)

    2016-03-22

    The project was successful in developing new sensing technologies for monitoring rates of microbial activity in soils and sediments and also developed a novel proof-of-concept for monitoring the presence of bioavailable concentrations of a diversity of metabolites and toxic components in sedimentary environments. These studies led not only to publications in the peer-reviewed literature, but also two patent applications and a start-up company.

  11. Characteristics of the surface-subsurface flow generation and sediment yield to the rainfall regime and land-cover by long-term in-situ observation in the red soil region, Southern China

    Science.gov (United States)

    Liu, Yao-Jun; Yang, Jie; Hu, Jian-Min; Tang, Chong-Jun; Zheng, Hai-Jin

    2016-08-01

    Land cover and rainfall regime are two important factors that affect soil erosion. In this paper, three land cover types - grass cover, litter cover and bare land - were employed to analyze surface runoff, subsurface flow and sediment loss processes in relation to the rainfall regimes in the red soil region of China. Five rainfall regimes were classified according to 393 rainfall events via a k-means clustering method based on the rainfall depth, duration and maximum 30-min intensity. The highest surface runoff coefficient and erosion amount were found on bare land in all five rainfall regimes, and the lowest were found on grass cover. The litter cover generated the highest subsurface flow rate, followed by the grass cover; the lowest was on bare land. For grass cover and litter cover plots, rainfall events of rainfall regime IV which had the longest duration, greatest depth and lowest intensity had the highest surface runoff coefficient, soil erosion amount and subsurface flow rate. For bare land, storm rainfall events of rainfall regime V had the highest intensity, lowest depth and duration, had the highest surface runoff coefficient and soil erosion amount, but the lowest subsurface flow rate. The highest subsurface flow rate of bare land happened in rainfall regime IV. Surface cover was urgently needed to reduce soil erosion. When the lands under dense surface cover, more attention should be paid to rainfall events that of long duration, high depth but low in intensity which commonly occurred in spring. The interactions of surface-subsurface flow and its effects on soil erosion and nutrient loss were worth considering in the red soil region.

  12. Sub-Surface Carbon Dioxide Concentration Measurement Using a Fiber Based Sensor in a Call/Return Geometry for Carbon Sequestration Site Monitoring

    Science.gov (United States)

    Wicks, G. R.; Soukup, B.; Repasky, K. S.; Carlsten, J.; Barr, J. L.; Dobeck, L.

    2010-12-01

    Geologic carbon sequestration is a means to mitigate the increasing atmospheric concentration of carbon dioxide (CO2) by capturing the CO2 at a source such as a power generation facility and storing the captured CO2 in geologic formations. Many technologic advances will need to occur for successful carbon sequestration including near surface monitoring tools and techniques to ensure site integrity and public safety. Researchers at Montana State University (MSU) are developing a scalable fiber sensor array in a call/return configuration for monitoring near sub-surface CO2 concentrations. The low cost fiber sensor array being developed at MSU for sub-surface CO2 detection for monitoring carbon sequestration sites will utilize a series of fiber probes connected to a two detectors and a 1 x N fiber switch that can direct the light to one of N fiber probes. The fiber sensor array will utilize a single tunable distributed feedback (DFB) diode laser with a center wavelength of 2.004 μm to access CO2 absorption features. The output from the DFB laser is incident on an inline fiber splitter that directs part of the light to a reference detector while the remaining light is directed to a fiber probe where the laser light interacts with the CO2. The light from the fiber probe is directed back through the switch and is incident on a transmission detector. The transmission as a function of wavelength is measured and a CO2 concentration is calculated. The fiber sensor array can easily be reconfigured by simply moving the fiber probes. Low cost is achieved by using inexpensive passive components in the fiber probes while limiting the number of the more expensive components including the DFB laser, the two detectors, and the single fiber switch. The fiber sensor was tested over a thirty day period at the Zero Emission Research Technology (ZERT) facility that was developed for testing surface and near surface carbon sequestration monitoring instrumentation using a controlled

  13. Subsurface Ventilation System Description Document

    Energy Technology Data Exchange (ETDEWEB)

    Eric Loros

    2001-07-25

    The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

  14. Subsurface Ventilation System Description Document

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-10-12

    The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

  15. The effects of DDoS attacks on flow monitoring applications

    NARCIS (Netherlands)

    Sadre, Ramin; Sperotto, Anna; Pras, Aiko

    2012-01-01

    Flow-based monitoring has become a popular approach in many areas of network management. However, flow monitoring is, by design, susceptible to anomalies that generate a large number of flows, such as Distributed Denial-Of-Service attacks. This paper aims at getting a better understanding on how a f

  16. The effects of DDoS attacks on flow monitoring applications

    NARCIS (Netherlands)

    Sadre, R.; Sperotto, Anna; Pras, Aiko

    Flow-based monitoring has become a popular approach in many areas of network management. However, flow monitoring is, by design, susceptible to anomalies that generate a large number of flows, such as Distributed Denial-Of-Service attacks. This paper aims at getting a better understanding on how a

  17. Paleomagnetic correlation of surface and subsurface basaltic lava flows and flow groups in the southern part of the Idaho National Laboratory, Idaho, with paleomagnetic data tables for drill cores

    Science.gov (United States)

    Champion, Duane E.; Hodges, Mary K.V.; Davis, Linda C.; Lanphere, Marvin A.

    2011-01-01

    Paleomagnetic inclination and polarity studies have been conducted on thousands of subcore samples from 51 coreholes located at and near the Idaho National Laboratory. These studies are used to paleomagnetically characterize and correlate successive stratigraphic intervals in each corehole to similar depth intervals in adjacent coreholes. Paleomagnetic results from 83 surface paleomagnetic sites, within and near the INL, are used to correlate these buried lava flow groups to basaltic shield volcanoes still exposed on the surface of the eastern Snake River Plain. Sample handling and demagnetization protocols are described as well as the paleomagnetic data averaging process. Paleomagnetic inclination comparisons between coreholes located only kilometers apart show comparable stratigraphic successions of mean inclination values over tens of meters of depth. At greater distance between coreholes, comparable correlation of mean inclination values is less consistent because flow groups may be missing or additional flow groups may be present and found at different depth intervals. Two shallow intersecting cross-sections, A-A- and B-B- (oriented southwest-northeast and northwest-southeast, respectively), drawn through southwest Idaho National Laboratory coreholes show the corehole to corehole or surface to corehole correlations derived from the paleomagnetic inclination data. From stratigraphic top to bottom, key results included the (1) Quaking Aspen Butte flow group, which erupted from Quaking Aspen Butte southwest of the Idaho National Laboratory, flowed northeast, and has been found in the subsurface in corehole USGS 132; (2) Vent 5206 flow group, which erupted near the southwestern border of the Idaho National Laboratory, flowed north and east, and has been found in the subsurface in coreholes USGS 132, USGS 129, USGS 131, USGS 127, USGS 130, USGS 128, and STF-AQ-01; and (3) Mid Butte flow group, which erupted north of U.S. Highway 20, flowed northwest, and has been

  18. Experimental measurements of the SP response to concentration and temperature gradients in sandstones with application to subsurface geophysical monitoring

    Science.gov (United States)

    Leinov, E.; Jackson, M. D.

    2014-09-01

    Exclusion-diffusion potentials arising from temperature gradients are widely neglected in self-potential (SP) surveys, despite the ubiquitous presence of temperature gradients in subsurface settings such as volcanoes and hot springs, geothermal fields, and oil reservoirs during production via water or steam injection. Likewise, with the exception of borehole SP logging, exclusion-diffusion potentials arising from concentration gradients are also neglected or, at best, it is assumed that the diffusion potential dominates. To better interpret these SP sources requires well-constrained measurements of the various coupling terms. We report measurements of thermoelectric and electrochemical exclusion-diffusion potentials across sandstones saturated with NaCl brine and find that electrode effects can dominate the measured voltage. After correcting for these, we find that Hittorf transport numbers are the same within experimental error regardless of whether ion transport occurs in response to temperature or concentration gradients over the range of NaCl concentration investigated that is typical of natural systems. Diffusion potentials dominate only if the pore throat radius is more than approximately 4000 times larger than the diffuse layer thickness. In fine-grained sandstones with small pore throat diameter, this condition is likely to be met only if the saturating brine is of relatively high salinity; thus, in many cases of interest to earth scientists, exclusion-diffusion potentials will comprise significant contributions from both ionic diffusion through, and ionic exclusion from, the pore space of the rock. However, in coarse-grained sandstones, or sandstones saturated with high-salinity brine, exclusion-diffusion potentials can be described using end-member models in which ionic exclusion is neglected. Exclusion-diffusion potentials in sandstones depend upon pore size and salinity in a complex way: they may be positive, negative, or zero depending upon sandstone

  19. Effects of interspecific competition on the growth of macrophytes and nutrient removal in constructed wetlands: A comparative assessment of free water surface and horizontal subsurface flow systems.

    Science.gov (United States)

    Zheng, Yucong; Wang, Xiaochang; Dzakpasu, Mawuli; Zhao, Yaqian; Ngo, Huu Hao; Guo, Wenshan; Ge, Yuan; Xiong, Jiaqing

    2016-05-01

    The outcome of competition between adjoining interspecific colonies of Phragmites and Typha in two large field pilot-scale free water surface (FWS) and subsurface flow (SSF) CWs is evaluated. According to findings, the effect of interspecific competition was notable for Phragmites australis, whereby it showed the highest growth performance in both FWS and SSF wetland. In a mixed-culture, P. australis demonstrates superiority in terms of competitive interactions for space between plants. Furthermore, the interspecific competition among planted species seemed to cause different ecological responses of plant species in the two CWs. For example, while relatively high density and shoot height determined the high aboveground dry weight of P. australis in the FWS wetland, this association was not evident in the SSF. Additionally, while plants nutrients uptake accounts for a higher proportion of the nitrogen removal in FWS, that in the SSF accounts for a higher proportion of the phosphorous removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Modeling flow cytometry data for cancer vaccine immune monitoring.

    Science.gov (United States)

    Frelinger, Jacob; Ottinger, Janet; Gouttefangeas, Cécile; Chan, Cliburn

    2010-09-01

    Flow cytometry (FCM) is widely used in cancer research for diagnosis, detection of minimal residual disease, as well as immune monitoring and profiling following immunotherapy. In all these applications, the challenge is to detect extremely rare cell subsets while avoiding spurious positive events. To achieve this objective, it helps to be able to analyze FCM data using multiple markers simultaneously, since the additional information provided often helps to minimize the number of false positive and false negative events, hence increasing both sensitivity and specificity. However, with manual gating, at most two markers can be examined in a single dot plot, and a sequential strategy is often used. As the sequential strategy discards events that fall outside preceding gates at each stage, the effectiveness of the strategy is difficult to evaluate without laborious and painstaking back-gating. Model-based analysis is a promising computational technique that works using information from all marker dimensions simultaneously, and offers an alternative approach to flow analysis that can usefully complement manual gating in the design of optimal gating strategies. Results from model-based analysis will be illustrated with examples from FCM assays commonly used in cancer immunotherapy laboratories.

  1. Analytical solution for tension-saturated and unsaturated flow from wicking porous pipes in subsurface irrigation: The Kornev-Philip legacies revisited

    Science.gov (United States)

    Kacimov, A. R.; Obnosov, Yu. V.

    2017-03-01

    The Russian engineer Kornev in his 1935 book raised perspectives of subsurface "negative pressure" irrigation, which have been overlooked in modern soil science. Kornev's autoirrigation utilizes wicking of a vacuumed water from a porous pipe into a dry adjacent soil. We link Kornev's technology with a slightly modified Philip (1984)'s analytical solutions for unsaturated flow from a 2-D cylindrical pipe in an infinite domain. Two Darcian flows are considered and connected through continuity of pressure along the pipe-soil contact. The first fragment is a thin porous pipe wall in which water seeps at tension saturation; the hydraulic head is a harmonic function varying purely radially across the wall. The Thiem solution in this fragment gives the boundary condition for azimuthally varying suction pressure in the second fragment, ambient soil, making the exterior of the pipe. The constant head, rather than Philip's isobaricity boundary condition, along the external wall slightly modifies Philip's formulae for the Kirchhoff potential and pressure head in the soil fragment. Flow characteristics (magnitudes of the Darcian velocity, total flow rate, and flow net) are explicitly expressed through series of Macdonald's functions. For a given pipe's external diameter, wall thickness, position of the pipe above a free water datum in the supply tank, saturated conductivities of the wall and soil, and soil's sorptive number, a nonlinear equation with respect to the total discharge from the pipe is obtained and solved by a computer algebra routine. Efficiency of irrigation is evaluated by computation of the moisture content within selected zones surrounding the porous pipe.Plain Language SummarySubsurface irrigation by "automatic" gadgets like pitchers or porous pipes is a water saving technology which minimizes evaporative losses and deep percolation. Moisture is emitted by capillary suction of a relatively dry soil and "thirsty" roots just in "right quantities", spontaneously

  2. The Cartridge Theory: a description of the functioning of horizontal subsurface flow constructed wetlands for wastewater treatment, based on modelling results.

    Science.gov (United States)

    Samsó, Roger; García, Joan

    2014-03-01

    Despite the fact that horizontal subsurface flow constructed wetlands have been in operation for several decades now, there is still no clear understanding of some of their most basic internal functioning patterns. To fill this knowledge gap, on this paper we present what we call "The Cartridge Theory". This theory was derived from simulation results obtained with the BIO_PORE model and explains the functioning of urban wastewater treatment wetlands based on the interaction between bacterial communities and the accumulated solids leading to clogging. In this paper we start by discussing some changes applied to the biokinetic model implemented in BIO_PORE (CWM1) so that the growth of bacterial communities is consistent with a well-known population dynamics models. This discussion, combined with simulation results for a pilot wetland system, led to the introduction of "The Cartridge Theory", which states that the granular media of horizontal subsurface flow wetlands can be assimilated to a generic cartridge which is progressively consumed (clogged) with inert solids from inlet to outlet. Simulations also revealed that bacterial communities are poorly distributed within the system and that their location is not static but changes over time, moving towards the outlet as a consequence of the progressive clogging of the granular media. According to these findings, the life-span of constructed wetlands corresponds to the time when bacterial communities are pushed as much towards the outlet that their biomass is not anymore sufficient to remove the desirable proportion of the influent pollutants. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Methodology of traffic flows remote monitoring in the Ural Federal District largest cities using satellite monitoring data

    Science.gov (United States)

    Testeshev, Alexander; Timohovetz, Vera

    2017-01-01

    The article considers the method of remote research of traffic flow characteristics in the largest cities based on satellite monitoring. The aim of the research is to develop mathematical conformities of traffic flow theory that allow interpreting the results of decoding the traffic situation static picture obtained from free online services into primary and derived traffic characteristics. Data on functional dependences of traffic density and traffic flow speed differentiated with respect to transport and road conditions is provided. The developed technique made it possible to minimize resource costs to conduct simultaneous monitoring of traffic flows on the road network in the largest cities of the Ural Federal District.

  4. Debris Flow Monitoring System and Observed Event in Taiwan: A Case Study at Aiyuzi River

    Institute of Scientific and Technical Information of China (English)

    HSIAO Taichung; LEE Bingjean; CHOU Tienyin; LIEN Huipain; CHANG Yinghuei

    2007-01-01

    Since 2002, the Soil and Water Conservation Bureau, which is responsible for the conservation and administrative management of hillside in Taiwan, has been cooperating with Feng Chia University. Together, they have successfully carried out the establishment and maintenance of 13 fixed debris flow monitoring stations over the island and 2 mobile debris flow monitoring stations. During July 2004, a powerful southwest air current brought by Mindulle Typhoon caused serious flood in central and southern Taiwan. This paper aims to describe the establishment of debris flow monitoring systems in Taiwan and the observation of the debris flow event during Mindulle Typhoon at Aiyuzi River in Shenmu Village, Nantou County by the monitoring station.

  5. Fluid flow monitoring in oilfields using downhole measurements of electrokinetic potential

    Science.gov (United States)

    Jackson, M. D.; Saunders, J. H.; Pain, C. C.

    2006-12-01

    Permanently installed downhole sensors are increasingly being deployed to provide `real-time' reservoir data during hydrocarbon production, which helps to reduce uncertainty in the reservoir description and contributes to reservoir management decisions. Where wells are equipped with inflow control valves (so called `intelligent' wells), it is possible to develop a feedback loop between measurement and control to optimize production. We suggest that measurements of electrokinetic potential during production, using permanently installed downhole electrodes, could be used to detect water encroachment towards an intelligent oil well. Downhole electrodes mounted at the production well on the outside of insulated casing, have been successfully applied in subsurface resistivity surveys during oil production. Similar technology could be used to measure electrokinetic potential. Moreover, recent and ongoing work has changed our understanding of electrokinetic coupling under two-phase conditions. We present the results of numerical simulations of fluid movement during hydrocarbon production, using a new formulation which captures both the changing fluid distributions and the resulting electrical potentials. We suggest that encroaching water causes changes in electrokinetic potential at the production well which could be resolved above background electrical noise; indeed, changes in water saturation could be detected several 10's to 100's of metres away from the well. This contrasts with most other downhole monitoring techniques, which sample only the region immediately adjacent to the wellbore. Signal resolution is improved if the water has a relatively low salinity, and the pressure gradient into the well is large. However, significant uncertainties remain concerning the nature of electrokinetic coupling during the flow of oil and water, particularly in mixed and oil-wet reservoirs.

  6. Subsurface Facility System Description Document

    Energy Technology Data Exchange (ETDEWEB)

    Eric Loros

    2001-07-31

    The Subsurface Facility System encompasses the location, arrangement, size, and spacing of the underground openings. This subsurface system includes accesses, alcoves, and drifts. This system provides access to the underground, provides for the emplacement of waste packages, provides openings to allow safe and secure work conditions, and interfaces with the natural barrier. This system includes what is now the Exploratory Studies Facility. The Subsurface Facility System physical location and general arrangement help support the long-term waste isolation objectives of the repository. The Subsurface Facility System locates the repository openings away from main traces of major faults, away from exposure to erosion, above the probable maximum flood elevation, and above the water table. The general arrangement, size, and spacing of the emplacement drifts support disposal of the entire inventory of waste packages based on the emplacement strategy. The Subsurface Facility System provides access ramps to safely facilitate development and emplacement operations. The Subsurface Facility System supports the development and emplacement operations by providing subsurface space for such systems as ventilation, utilities, safety, monitoring, and transportation.

  7. Role of vegetation (Typha latifolia) on nutrient removal in a horizontal subsurface-flow constructed wetland treating UASB reactor-trickling filter effluent.

    Science.gov (United States)

    da Costa, Jocilene Ferreira; Martins, Weber Luiz Pinto; Seidl, Martin; von Sperling, Marcos

    2015-01-01

    The main objective of the work is to characterize the role of plants in a constructed wetland in the removal of nitrogen (N) and phosphorus (P). The experiments were carried out in a full-scale system in the city of Belo Horizonte, Brazil, with two parallel horizontal subsurface-flow constructed wetland units (one planted with Typha latifolia and one unplanted) treating the effluent from a system composed of an upflow anaerobic sludge blanket reactor and a trickling filter (TF). Each wetland unit received a mean flow of approximately 8.5 m³ d⁻¹ (population equivalent around 60 inhabitants each), with a surface hydraulic loading rate 0.12 m³m⁻²d⁻¹. The experiments were conducted from September 2011 to July 2013. Mean effluent concentrations from the wetlands were: (a) planted unit total nitrogen (TN) 22 mg L⁻¹, ammonia-N 19 mg L⁻¹, nitrite-N 0.10 mg L⁻¹, nitrate-N 0.25 mg L⁻¹, P-total 1.31 mg L⁻¹; and (b) unplanted unit TN 24 mg L⁻¹, ammonia-N 20 mg L⁻¹, nitrite-N 0.54 mg mL⁻¹, nitrate-N 0.15 mg L⁻¹, P-total 1.31 mg L⁻¹. The aerial part of the plant contained mean values of 24.1 gN (kg dry matter)⁻¹ and 4.4 gP (kg dry matter)⁻¹, and the plant root zone was composed of 16.5 gN (kg dry matter)⁻¹ and 4.1 gP (kg dry matter)⁻¹. The mean extraction of N by the plant biomass was 726 kgN ha⁻¹y⁻¹, corresponding to 17% of the N load removed. For P, the extraction by the plant biomass was 105 kgP ha⁻¹y⁻¹, corresponding to 9% of the P load removed. These results reinforce the reports that N and P removal due to plant uptake is a minor mechanism in horizontal subsurface-flow constructed wetlands operating under similar loading rates, typical for polishing of sanitary effluent.

  8. Collecting and Storing Data Flow Monitoring in Elasticsearch

    CERN Document Server

    Hashim, Fatin Hazwani

    2014-01-01

    A very large amount of data is produced from the online data flow monitoring for the CMS data acquisition system. However, there are only a small portion of data is stored permanently in the relational database. This is because of the high cost needed while relying on the dedicated infrastructure as well as the issues in its performance itself. A new approach needs to be found in order to confront such a big volume of data known as “Big Data”. The Big Data [1] is the term given to the very large and complex data sets that cannot be handled by the traditional data processing application [2] in terms of capturing, storing, managing, and analyzing. The sheer size of the data [3] in CMS data acquisition system is one of the major challenges, and is the one of the most easily recognized. New technology need to be used as the alternative of the traditional databases initial evaluation to handle this problem as more data need to be stored permanently and can be easily retrieved. This report consists of the intro...

  9. Hillslope-storage Boussinesq model for subsurface flow and variable source areas along complex hillslopes: 1. Formulation and characteristic response

    NARCIS (Netherlands)

    Troch, P.A.A.; Paniconi, C.; Loon, van E.E.

    2003-01-01

    Hillslope response to rainfall remains one of the central problems of catchment hydrology. Flow processes in a one-dimensional sloping aquifer can be described by Boussinesq's hydraulic groundwater theory. Most hillslopes, however, have complex three-dimensional shapes that are characterized by thei

  10. Direct Forecasting of Subsurface Flow Response from Non-Linear Dynamic Data By Linear Least-Squares in Canonical Functional Principal Component Space.

    Science.gov (United States)

    Satija, A.; Caers, J.

    2014-12-01

    Hydrogeological forecasting problems, like many subsurface forecasting problems, often suffer from the scarcity of reliable data yet complex prior information about the underlying earth system. Assimilating and integrating this information into an earth model requires using iterative parameter space exploration techniques or Monte Carlo Markov Chain techniques. Since such an earth model needs to account for many large and small scale features of the underlying system, as the system gets larger, iterative modeling can become computationally prohibitive, in particular when the forward model would allow for only a few hundred model evaluations. In addition, most modeling methods do not include the purpose for which inverse method are built, namely, the actual forecast and usually focus only on data and model. In this study, we present a technique to extract features of the earth system informed by time-varying dynamic data (data features) and those that inform a time-varying forecasting variable (forecast features) using Functional Principal Component Analysis. Canonical Coefficient Analysis is then used to examine the relationship between these features using a linear model. When this relationship suggests that the available data informs the required forecast, a simple linear regression can be used on the linear model to directly estimate the posterior of the forecasting problem, without any iterative inversion of model parameters. This idea and method is illustrated using an example of contaminant flow in an aquifer with complex prior, large dimension and non-linear flow & transport model.

  11. Treatment of a sulfate-rich groundwater contaminated with perchloroethene in a hydroponic plant root mat filter and a horizontal subsurface flow constructed wetland at pilot-scale.

    Science.gov (United States)

    Chen, Zhongbing; Kuschk, Peter; Paschke, Heidrun; Kästner, Matthias; Müller, Jochen A; Köser, Heinz

    2014-12-01

    A hydroponic plant root mat filter (HPRMF) was compared over 7months with a horizontal subsurface flow constructed wetland (HSSF CW) regarding the removal of perchloroethene (PCE) (about 2 mg L(-1)) from a sulfate- (850 mg L(-1)) and ammonia-rich (50 mg L(-1)) groundwater with a low TOC content. At a mean area specific inflow PCE load of 56 mg m(-2)d(-1), after 4m from inlet, the mean PCE removal during summer time reached 97% in the HPRMF and almost 100% in the HSSF CW. Within the first 2m in the HSSF CW metabolites like dichloroethenes, vinyl chloride and ethene accumulated, their concentrations decreased further along the flow path. Moreover, the tidal operation (a 7-d cycle) in the HSSFCW decreased the accumulation of PCE metabolites within the first 1m of the bed. The carcinogenic degradation metabolite vinyl chloride was not detected in the HPRMF. The smaller accumulation of the degradation metabolites in the HPRMF correlated with its higher redox potential. It can be concluded from this study that HPRMF appears an interesting alternative for special water treatment tasks and that tidal operation will show some positive effects on the removal of the accumulated PCE metabolites in HSSF CW. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Final Report: DoE SBIR Phase 2 Low-Cost Small Diameter NMR Technologies for In-Situ Subsurface Characterization and Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, David Oliver [Vista Clara Inc., Mukilteo, WA (United States)

    2010-09-03

    In this Phase 2 SBIR program, Vista Clara successfully developed and field-tested small diameter NNR logging tools for subsurface characterization and monitoring. This effort involved the design and development surface electronics, a winch with 470ft cable, and three interchangeable downhole probes: a 3.5â diameter borehole NMR probe, a 1.67â diameter borehole NMR probe, and a 2.5â diameter NMR probe that can be deployed using a Geoprobe direct push machine. The 3.5â probe was tested extensively over a 6 week period including 4â to 8â boreholes in Washington, Idaho, Nebraska, Colorado, Kansas, Connecticut and Massachusetts. The field test campaign was highly successful. The 1.67â probe was assembled, tested and calibrated in the laboratory. The 2.5â Geoprobe probe is in final assembly and testing at the time of this report. The completed Phase 2 R&D program has resulted in the first NMR logging tool that can be deployed in boreholes of 4â diameter, the first NMR logging tool that can be deployed in boreholes on 2â diameter, and the first NMR logging tool that can be deployed by a direct push machine. These small diameter tools make NMR logging technically and economically feasible, for the first time. Previously available NMR logging tools were developed for oilfield applications and are prohibitively large and expensive for the majority of near surface groundwater characterization problems.

  13. dfnWorks: A HPC Workflow for Discrete Fracture Network Modeling with Subsurface Flow and Transport Applications

    Science.gov (United States)

    Gable, C. W.; Hyman, J.; Karra, S.; Makedonska, N.; Painter, S. L.; Viswanathan, H. S.

    2015-12-01

    dfnWorks generates discrete fracture networks (DFN) of planar polygons, creates a high quality conforming Delaunay triangulation of the intersecting DFN polygons, assigns properties (aperture, permeability) using geostatistics, sets boundary and initial conditions, solves pressure/flow in single or multi-phase fluids (water, air, CO2) using the parallel PFLOTRAN or serial FEHM, and solves for transport using Lagrangian particle tracking. We outline the dfnWorks workflow and present applications from a range of fractured rock systems. dfnWorks (http://www.lanl.gov/expertise/teams/view/dfnworks) is composed of three main components, all of which are freely available. dfnGen generates a distribution of fracture polygons from site characterization data (statistics or deterministic fractures) and utilizes the FRAM (Feature Rejection Algorithm for Meshing) to guarantee the mesh generation package LaGriT (lagrit.lanl.gov) will generate a high quality conforming Delaunay triangular mesh. dfnWorks links the mesh to either PFLOTRAN (pflotran.org) or FEHM (fehm.lanl.gov) for solving flow and transport. The various physics options available in FEHM and PFLOTRAN such as single and multi-phase flow and reactive transport are all available with appropriate initial and boundary conditions and material property models. dfnTrans utilizes explicit Lagrangian particle tracking on the DFN using a velocity field reconstructed from the steady state pressure/flow field solution obtained in PFLOTRAN or FEHM. Applications are demonstrated for nuclear waste repository in fractured granite, CO2 sequestration and extraction of unconventional hydrocarbon resources.

  14. Integrated cantilever-based flow sensors with tunable sensitivity for in-line monitoring of flow fluctuations in microfluidic systems

    DEFF Research Database (Denmark)

    Noeth, Nadine-Nicole; Keller, Stephan Sylvest; Boisen, Anja

    2014-01-01

    For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different m...... pumps connected to the microfluidic system. © 2013 by the authors; licensee MDPI, Basel, Switzerland....

  15. Scenario simulation based assessment of subsurface energy storage

    Science.gov (United States)

    Beyer, C.; Bauer, S.; Dahmke, A.

    2014-12-01

    Energy production from renewable sources such as solar or wind power is characterized by temporally varying power supply. The politically intended transition towards renewable energies in Germany („Energiewende") hence requires the installation of energy storage technologies to compensate for the fluctuating production. In this context, subsurface energy storage represents a viable option due to large potential storage capacities and the wide prevalence of suited geological formations. Technologies for subsurface energy storage comprise cavern or deep porous media storage of synthetic hydrogen or methane from electrolysis and methanization, or compressed air, as well as heat storage in shallow or moderately deep porous formations. Pressure build-up, fluid displacement or temperature changes induced by such operations may affect local and regional groundwater flow, geomechanical behavior, groundwater geochemistry and microbiology. Moreover, subsurface energy storage may interact and possibly be in conflict with other "uses" like drinking water abstraction or ecological goods and functions. An utilization of the subsurface for energy storage therefore requires an adequate system and process understanding for the evaluation and assessment of possible impacts of specific storage operations on other types of subsurface use, the affected environment and protected entities. This contribution presents the framework of the ANGUS+ project, in which tools and methods are developed for these types of assessments. Synthetic but still realistic scenarios of geological energy storage are derived and parameterized for representative North German storage sites by data acquisition and evaluation, and experimental work. Coupled numerical hydraulic, thermal, mechanical and reactive transport (THMC) simulation tools are developed and applied to simulate the energy storage and subsurface usage scenarios, which are analyzed for an assessment and generalization of the imposed THMC

  16. Noble gas fractionation during subsurface gas migration

    Science.gov (United States)

    Sathaye, Kiran J.; Larson, Toti E.; Hesse, Marc A.

    2016-09-01

    Environmental monitoring of shale gas production and geological carbon dioxide (CO2) storage requires identification of subsurface gas sources. Noble gases provide a powerful tool to distinguish different sources if the modifications of the gas composition during transport can be accounted for. Despite the recognition of compositional changes due to gas migration in the subsurface, the interpretation of geochemical data relies largely on zero-dimensional mixing and fractionation models. Here we present two-phase flow column experiments that demonstrate these changes. Water containing a dissolved noble gas is displaced by gas comprised of CO2 and argon. We observe a characteristic pattern of initial co-enrichment of noble gases from both phases in banks at the gas front, followed by a depletion of the dissolved noble gas. The enrichment of the co-injected noble gas is due to the dissolution of the more soluble major gas component, while the enrichment of the dissolved noble gas is due to stripping from the groundwater. These processes amount to chromatographic separations that occur during two-phase flow and can be predicted by the theory of gas injection. This theory provides a mechanistic basis for noble gas fractionation during gas migration and improves our ability to identify subsurface gas sources after post-genetic modification. Finally, we show that compositional changes due to two-phase flow can qualitatively explain the spatial compositional trends observed within the Bravo Dome natural CO2 reservoir and some regional compositional trends observed in drinking water wells overlying the Marcellus and Barnett shale regions. In both cases, only the migration of a gas with constant source composition is required, rather than multi-stage mixing and fractionation models previously proposed.

  17. A Theoretical Study of Subsurface Drainage Model Simulation of ...

    African Journals Online (AJOL)

    A Theoretical Study of Subsurface Drainage Model Simulation of Drainage Flow and ... of subsurface drain spacing, evapotranspiration and irrigation water quality on ... The study was carried out on a conceptual uniform homogenous irrigated ...

  18. Shallow subsurface temperature and moisture monitoring at rock walls during freeze thaw cycles in the Northern Calcareous Alps, Austria

    Science.gov (United States)

    Rode, Matthias; Sass, Oliver

    2014-05-01

    The process of frost weathering as well as the contribution of further weathering processes (e.g. hydration, thermal fatigue) is poorly understood. For this purpose, different measuring systems were set up in two study areas (Dachstein massif - permafrost area (2700m asl, 47° 28' 32″ N, 13° 36' 23″ E) and Gesäuse mountains - non permafrost area (900m asl, 47° 35' 19″ N, 14° 39' 32″ E) located in Styria, Austria within the framework of the research project ROCKING ALPS (FWF-P2444). A key to understand frost weathering is to observe the rock temperature with several high resolution temperature sensors from the rock surface down to -20cm depth. The temperatures are measured hourly at north and south exposed rock walls since 2012 in the headwalls of the Dachstein glacier at the Koppenkarstein (built up of limestone) in about 2600m asl. Since 2013 the same measurement setup is installed in the lower Johnsbachtal (Gesäuse mountains, prevailing rock type is dolomite) in about 800m asl. To know the temperature is crucial to understand internal heat flow and transport and latent heat effects during freezing and thawing caused by night frost (lasting some hours), cold fronts (lasting some days) or winter frost of several weeks or months. At these study points we also have installed small-scale 2D-geoelectric survey lines, supplemented by moisture sensors. Moisture is determined by means of resistivity measurements which are difficult to calibrate, but provide good time series. Additional novel moisture sensors were developed which use the heat capacity of the surrounding rock as a proxy of water content. These sensors give point readings from a defined depth and are independent from soluble salt contents. First results from the Dachstein show that short term latent heat effects during the phase change have crucial influence on the moisture content. The moisture distribution and movements during temperature changes inside the rock are discussed upon the two main

  19. TOUGHREACT Version 2.0: A simulator for subsurface reactive transport under non-isothermal multiphase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Xu, T.; Spycher, N.; Sonnenthal, E.; Zhang, G.; Zheng, L.; Pruess, K.

    2010-08-01

    TOUGHREACT is a numerical simulation program for chemically reactive non-isothermal flows of multiphase fluids in porous and fractured media, and was developed by introducing reactive chemistry into the multiphase fluid and heat flow simulator TOUGH2 V2. The first version of TOUGHREACT was released to the public through the U.S. Department of Energy's Energy Science and Technology Software Center (ESTSC) in August 2004. It is among the most frequently requested of ESTSC's codes. The code has been widely used for studies in CO{sub 2} geological sequestration, nuclear waste isolation, geothermal energy development, environmental remediation, and increasingly for petroleum applications. Over the past several years, many new capabilities have been developed, which were incorporated into Version 2 of TOUGHREACT. Major additions and improvements in Version 2 are discussed here, and two application examples are presented: (1) long-term fate of injected CO{sub 2} in a storage reservoir and (2) biogeochemical cycling of metals in mining-impacted lake sediments.

  20. Continuous monitoring of the C isotope composition of CO_{2}-rich subsurface degassing at Tenerife, Canary Islands

    Science.gov (United States)

    Melián, Gladys; Asensio-Ramos, María; Padrón, Eleazar; Barrancos, José; Hernández, Pedro A.; Pérez, Nemesio M.

    2017-04-01

    gas bubbling spot (˜-4.7‰ unpublished data) and analyzed with a Thermo Finnigan MAT 253 isotope ratio mass spectrometer, which supports the validity of the analytical method used. This is the first time that this type of instrumentation is used to continuously monitor the δ13C(CO2) isotopic composition of the gas discharged from a gas bubbling in a horizontal drill as a geochemical tool to evaluate the volcanic activity, in particular in Tenerife, a unique natural-scale laboratory for hydrological studies in oceanic volcanic islands. To correlate temporal variations in the δ13C(CO2) isotopic composition with changes in the seismic-volcanic activity of Tenerife, a longer observation period will be required. References: Pérez et al., 2007. Pure Appl. Geophys. DOI 10.1007/s00024-007-0280

  1. Effects of Solar Loading and Other Environmental Conditions on Thermographic Imaging of Subsurface Defects in Concrete

    Science.gov (United States)

    Washer, G. A.; Fenwick, R. G.; Bolleni, N.; Harper, J.

    2009-03-01

    The detection of subsurface defects in concrete using infrared cameras relies on thermal variations in the ambient environment to provide heat flow. Solar loading can provide significant thermal energy that enables the imaging of subsurface defects. This paper presents results of a study to determine the optimum environmental conditions for conducting thermal inspection of concrete bridges. This study has included continuous monitoring of a large concrete specimen under ambient environmental condition in central Missouri. The thermal contrast of subsurface targets in the specimen has been analyzed to determine the optimum conditions and time for detection of subsurface features as a function of depth. Environmental conditions that result in the largest contrast in surface temperature are discussed.

  2. A new debris flow monitoring barrier to measure debris flow impact/structure/ground interaction in the Gadria torrent

    Science.gov (United States)

    Nagl, Georg; Hübl, Johannes

    2017-04-01

    Debris flow monitoring is a keystone in debris flow research. Based on the lack of investigations of the interaction of rapid mass movement and structural mitigation measures, a new monitoring system has been installed in the well monitored Gadria torrent in South Tyrol. For design of active structural measures, like check dams, the engineering task is to come to an amicable solution of all necessary subjects. Starting with the estimation of parameters of the rapid mass movement itself to the design load and finally to the foundation of the structure. At all stages big uncertainties are given. The basis for accurate design is a comprehensive approach. For this reason, a new monitoring station was built in autumn 2016, to investigate the interaction of a debris flow with the structures and the ground. Two structures unify the new monitoring system. The first, a transversal check dam, flush to channel bed, contain two weighing devices each equipped with a pore pressure sensor. One device is also able to measure the shear force additional in two directions. The second barrier similar to a debris flow breaker but only with one singe wall centered on a foundation plate, is located downstream to the first one. 14 load cells are installed on the upward front of the structure to analyze the spatial force distribution of debris flow impact pressure. Nine earth pressure sensors under the foundation of the structure deliver the earth pressure distribution. The acceleration of the construction can be measured by a 3D accelerometer installed on the top. In case of a movement, two extensometers detect any displacement. Mounted strain gauges give insights of stresses in concrete and reinforcement. Each sensor has a sampling frequency of 2400 Hz. Furthermore it is planned to measure the flow velocity distribution over flow depth too. The new monitoring station should help to acquire data for understanding the debris flow/structure/ground interaction to facilitate the improvement

  3. Performance comparison and economics analysis of waste stabilization ponds and horizontal subsurface flow constructed wetlands treating domestic wastewater: a case study of the Juja sewage treatment works.

    Science.gov (United States)

    Mburu, Njenga; Tebitendwa, Sylvie M; van Bruggen, Johan J A; Rousseau, Diederik P L; Lens, Piet N L

    2013-10-15

    The performance, effluent quality, land area requirement, investment and operation costs of a full-scale waste stabilization pond (WSP) and a pilot scale horizontal subsurface flow constructed wetland (HSSF-CW) at Jomo Kenyatta University of Agriculture and Technology (JKUAT) were investigated between November 2010 to January 2011. Both systems gave comparable medium to high levels of organic matter and suspended solids removal. However, the WSP showed a better removal for Total Phosphorus (TP) and Ammonium (NH4(+)-N). Based on the population equivalent calculations, the land area requirement per person equivalent of the WSP system was 3 times the area that would be required for the HSSF-CW to treat the same amount of wastewater. The total annual cost estimates consisting of capital, operation and maintenance (O&M) costs were comparable for both systems. However, the evaluation of the capital cost of either system showed that it is largely influenced by the size of the population served, local cost of land and the construction materials involved. Hence, one can select either system in terms of treatment efficiency. When land is available other factor including the volume of wastewater or the investment, and O&M costs determine the technology selection. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Comparative evaluation of pilot scale horizontal subsurface-flow constructed wetlands and plant root mats for treating groundwater contaminated with benzene and MTBE.

    Science.gov (United States)

    Chen, Zhongbing; Kuschk, Peter; Reiche, Nils; Borsdorf, Helko; Kästner, Matthias; Köser, Heinz

    2012-03-30

    In order to evaluate technology options for the treatment of groundwater contaminated with benzene and MTBE in constructed wetlands (CWs), a scarcely applied plant root mat system and two horizontal subsurface-flow (HSSF) CWs were investigated. The inflow load of benzene and MTBE were 188-522 and 31-90 mg d(-1)m(-2), respectively. Higher removal efficiencies were obtained during summer in all systems. The benzene removal efficiencies were 0-33%, 24-100% and 22-100% in the unplanted HSSF-CW, planted HSSF-CW and the plant root mat, respectively; the MTBE removal efficiencies amounted to 0-33%, 16-93% and 8-93% in the unplanted HSSF-CW, planted HSSF-CW and the plant root mat, respectively. The volatilisation rates in the plant root mat amounted to 7.24 and 2.32 mg d(-1)m(-2) for benzene and MTBE, which is equivalent to 3.0% and 15.2% of the total removal. The volatilisation rates in the HSSF-CW reached 2.59 and 1.07 mg d(-1)m(-2), corresponding to 1.1% and 6.1% of the total removal of benzene and MTBE, respectively. The results indicate that plant root mats are an interesting option for the treatment of waters polluted with benzene and MTBE under moderate temperatures conditions. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Application of divided convective-dispersive transport model to simulate conservative transport processes in planted horizontal sub-surface flow constructed wetlands.

    Science.gov (United States)

    Dittrich, Ernő; Klincsik, Mihály

    2015-11-01

    We have created a divided convective-dispersive transport (D-CDT) model that can be used to provide an accurate simulation of conservative transport processes in planted horizontal sub-surface flow constructed wetlands filled with coarse gravel (HSFCW-C). This model makes a fitted response curve from the sum of two independent CDT curves, which show the contributions of the main and side streams. The analytical solutions of both CDT curves are inverse Gaussian distribution functions. We used Fréchet distribution to provide a fast optimization mathematical procedure. As a result of our detailed analysis, we concluded that the most important role in the fast upward part of the tracer response curve is played by the main stream, with high porous velocity and dispersion. This gives the first inverse Gaussian distribution function. The side stream shows slower transport processes in the micro-porous system, and this shows the impact of back-mixing and dead zones, too. The significance of this new model is that it can simulate transport processes in this kind of systems more accurately than the conventionally used convective-dispersive transport (CDT) model. The calculated velocity and dispersion coefficients with the D-CDT model gave differences of 24-54% (of velocity) and 22-308% (of dispersion coeff.) from the conventional CDT model, and were closer to actual hydraulic behaviour.

  6. Analysis of conservative tracer measurement results using the Frechet distribution at planted horizontal subsurface flow constructed wetlands filled with coarse gravel and showing the effect of clogging processes.

    Science.gov (United States)

    Dittrich, Ernő; Klincsik, Mihály

    2015-11-01

    A mathematical process, developed in Maple environment, has been successful in decreasing the error of measurement results and in the precise calculation of the moments of corrected tracer functions. It was proved that with this process, the measured tracer results of horizontal subsurface flow constructed wetlands filled with coarse gravel (HSFCW-C) can be fitted more accurately than with the conventionally used distribution functions (Gaussian, Lognormal, Fick (Inverse Gaussian) and Gamma). This statement is true only for the planted HSFCW-Cs. The analysis of unplanted HSFCW-Cs needs more research. The result of the analysis shows that the conventional solutions (completely stirred series tank reactor (CSTR) model and convection-dispersion transport (CDT) model) cannot describe these types of transport processes with sufficient accuracy. These outcomes can help in developing better process descriptions of very difficult transport processes in HSFCW-Cs. Furthermore, a new mathematical process can be developed for the calculation of real hydraulic residence time (HRT) and dispersion coefficient values. The presented method can be generalized to other kinds of hydraulic environments.

  7. High-throughput pyrosequencing analysis of bacteria relevant to cometabolic and metabolic degradation of ibuprofen in horizontal subsurface flow constructed wetlands.

    Science.gov (United States)

    Li, Yifei; Wu, Bing; Zhu, Guibing; Liu, Yu; Ng, Wun Jern; Appan, Adhityan; Tan, Soon Keat

    2016-08-15

    The potential toxicity of pharmaceutical residues including ibuprofen on the aquatic vertebrates and invertebrates has attracted growing attention to the pharmaceutical pollution control using constructed wetlands, but there lacks of an insight into the relevant microbial degradation mechanisms. This study investigated the bacteria associated with the cometabolic and metabolic degradation of ibuprofen in a horizontal subsurface flow constructed wetland system by high-throughput pyrosequencing analysis. The ibuprofen degradation dynamics, bacterial diversity and evenness, and bacterial community structure in a planted bed with Typha angustifolia and an unplanted bed (control) were compared. The results showed that the plants promoted the microbial degradation of ibuprofen, especially at the downstream zones of wetland. However, at the upstream one-third zone of wetland, the presence of plants did not significantly enhance ibuprofen degradation, probably due to the much greater contribution of cometabolic behaviors of certain non-ibuprofen-degrading microorganisms than that of the plants. By analyzing bacterial characteristics, we found that: (1) The aerobic species of family Flavobacteriaceae, family Methylococcaceae and genus Methylocystis, and the anaerobic species of family Spirochaetaceae and genus Clostridium_sensu_stricto were the most possible bacteria relevant to the cometabolic degradation of ibuprofen; (2) The family Rhodocyclaceae and the genus Ignavibacterium closely related to the plants appeared to be associated with the metabolic degradation of ibuprofen.

  8. UASB followed by Sub-Surface Horizontal Flow Phytodepuration for the Treatment of the Sewage Generated by a Small Rural Community

    Directory of Open Access Journals (Sweden)

    Massimo Raboni

    2014-10-01

    Full Text Available The paper presents the results of an experimental process designed for the treatment of the sewage generated by a rural community located in the north-east of Brazil. The process consists of a preliminary mechanical treatment adopting coarse screens and grit traps, followed by a biological treatment in a UASB reactor and a sub-surface horizontal flow phytodepuration step. The use of a UASB reactor equipped with a top cover, as well as of the phytodepuration process employing a porous medium, showed to present important health advantages. In particular, there were no significant odor emissions and there was no evidence of the proliferation of insects and other disease vectors. The plant achieved the following mean abatement efficiencies: 92.9% for BOD5, 79.2% for COD and 94% for Suspended Solids. With regard to fecal indicators average efficiencies of 98.8% for fecal coliforms and 97.9% for fecal enterococci were achieved. The UASB reactor showed an important role in achieving this result. The research was also aimed at evaluating the optimal operating conditions for the UASB reactor in terms of hydraulic load and organic volumetric loading. The achieved results hence indicated that the process may be highly effective for small rural communities in tropical and sub-tropical areas.

  9. Effect of operational and design parameters on performance of pilot-scale horizontal subsurface flow constructed wetlands treating university campus wastewater.

    Science.gov (United States)

    Papaevangelou, Vassiliki; Gikas, Georgios D; Tsihrintzis, Vassilios A

    2016-10-01

    Three horizontal subsurface flow (HSF) pilot-scale constructed wetland (CW) units operated for 3 years treating municipal wastewater originating from a university campus. The main objective of the study was the evaluation of the performance of these systems under several operational, design, and climatic conditions. Several parameters and factors were investigated, including the influence of temperature, vegetation, and hydraulic residence time. The results were compared to those of a previous study conducted in the same pilot-scale units and under the same operational conditions where synthetic municipal wastewater was used. Results show the satisfying overall performance of the CW units. Performance seems to be influenced by vegetation, temperature, and hydraulic residence time (HRT). The planted units produced better results than the unplanted one while, generally, all units operated better under warmer conditions. In addition, longer HRTs contributed to higher removal efficiencies. Finally, the systems showed higher removal efficiencies in the previous study (synthetic wastewater) regarding organic matter removal, while for the other pollutants, the present study (real wastewater) showed higher or comparable performance in most cases and especially in the planted units. The study also shows the overall good, continuous, and long-term operation of CW systems, since these systems operate for about 13 years.

  10. A study of K variability and its effect on solute transport in subsurface-flow sand filters by measurement and modelling.

    Science.gov (United States)

    Kløve, Bjørn; Xu, Shulan; Lindahl, Anna; Wörman, Anders; Søvik, Anne-Kristine

    2005-01-01

    Hydraulics of subsurface flow filters (SSF) was studied by measurement of soil hydraulic conductivity (K) variation and performing tracer tests in two SSF filters consisting of 1-4 mm Ca rich sand (shell sand). Soil samples were carefully taken at several locations in Filter I. A tracer experiment was conducted in the undisturbed Filter II using KI. The measured K variability in Filer I was used to analyze the variations in tracer breakthrough. The spatially distribution of K was obtained by fitting a variogram to observed data and interpolation using Kriging. The tracer residence probability density function (PDF) was determined by modelling the tracer movement with a 3-D groundwater model. The observed and simulated tracer arrival was compared for cases with constant K, constant K and dispersion (D), and for spatially variable K and dispersion. The results show that groundwater models were well suited to simulate solute movement in the SSF system studied. An almost perfect fit to observed tracer PDF was obtained when variable K and dispersion was included in the model. This indicates that information on K variability and dispersion is important for studying solute movement in SSF constructed wetlands.

  11. Application of Horizontal Subsurface Flow Constructed Wetland Systems for Domestic Wastewater Treatment: A Case Study, Kızılcaören

    Directory of Open Access Journals (Sweden)

    Fulya Aydın Temel

    2017-06-01

    Full Text Available Constructed wetlands (CWs are a green technology that have been used to treat several types of wastewater such as domestic, industrial, agricultural wastewaters and landfill leachate. CWs have several advantages included land intensive, low energy, easy operation and maintenance, low investment/operational costs, landscape esthetics, reuse of waters, and increased wildlife habitat compared to conventional systems. CWs are alternative treatment technologies due to these properties especially for rural settlements, industries, and hotels that are remote locations from central treatment plants. Physical, chemical, and biological treatment mechanisms can employ together in CWs. In the present study, two parallel full scale horizontal subsurface flow constructed wetlands were designed to treat domestic wastewater of Kızılcaören village in Samsun, Turkey. Juncus acutus and Cortaderia selloana were selected and the removal performance of each species were evaluated. During 7 months operation, the mean removal efficiencies of Juncus acutus and Cortaderia selloana were found as 33% and 32% for Mg2+; 62% and 55% for Fe2+; 64% and 56% for Fe3+; 46% and 37% for Cl2; 48% and 39% for total Cl2; 26% and 37% for Ca2+; 28% and 23% for SAA, respectively. Also, the Two-way ANOVA between groups was applied to determine any difference for the removal of all parameters between the plant types and months on the mean values of pollutants removal.

  12. Integrated cantilever-based flow sensors with tunable sensitivity for in-line monitoring of flow fluctuations in microfluidic systems.

    Science.gov (United States)

    Noeth, Nadine; Keller, Stephan Sylvest; Boisen, Anja

    2013-12-23

    For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different materials (SU-8 and SiN) and with different thicknesses. The integration of arrays of holes with different hole size and number of holes allows the modification of device sensitivity, theoretical detection limit and measurement range. For an average flow in the microliter range, the cantilever deflection is directly proportional to the flow rate fluctuations in the microfluidic channel. The SiN cantilevers show a detection limit below 1 nL/min and the thinnest SU-8 cantilevers a detection limit below 5 nL/min. Finally, the sensor is applied for in-line monitoring of flow fluctuations generated by external pumps connected to the microfluidic system.

  13. Integrated Cantilever-Based Flow Sensors with Tunable Sensitivity for In-Line Monitoring of Flow Fluctuations in Microfluidic Systems

    Directory of Open Access Journals (Sweden)

    Nadine Noeth

    2013-12-01

    Full Text Available For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different materials (SU-8 and SiN and with different thicknesses. The integration of arrays of holes with different hole size and number of holes allows the modification of device sensitivity, theoretical detection limit and measurement range. For an average flow in the microliter range, the cantilever deflection is directly proportional to the flow rate fluctuations in the microfluidic channel. The SiN cantilevers show a detection limit below 1 nL/min and the thinnest SU-8 cantilevers a detection limit below 5 nL/min. Finally, the sensor is applied for in-line monitoring of flow fluctuations generated by external pumps connected to the microfluidic system.

  14. Olive mill wastewater treatment by a pilot-scale subsurface horizontal flow (SSF-h) constructed wetland.

    Science.gov (United States)

    Del Bubba, Massimo; Checchini, Leonardo; Pifferi, Chiara; Zanieri, Laura; Lepri, Luciano

    2004-12-01

    Performances of a pilot-scale reed bed for the olive mill wastewater (OMW) treatment were investigated, by monitoring influent and effluent pH, total suspended solids (TSS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), total phosphorus and polyphenols. In order to reduce the suspended matter concentration and to avoid clogging, OMW was pre-treated by adding lime putty, calcium hydroxide and hydraulic lime. The best results were obtained with 2 g/L of hydraulic lime. Pre-treated OMW was dosed in the reed bed at dilution ratios of 1/3 and 1/10 (v/v), pointing up that the latter only did not give rise to reed suffering and allowed to obtain good and durable removal efficiencies, above all for COD (74.1+/-17.6%) and polyphenols (83.4+/-17.8%). Recycling of the effluent was quite effective for the improvement of the wastewater quality, allowing a further removal of 26-70%, depending on the parameter taken into account. A post-dosage study, carried out by feeding the reed bed with the effluent of an activated sludge plant, pointed up a rapid decreasing of the outlet concentrations of the investigated parameters to values compatible with Italian regulations concerning wastewater discharge in surface water. Polyphenols were the exception, being their outlet concentration at the end of post-dosage study around 2 mg/L.

  15. Note: Signal conditioning of a hot-film anemometer for a periodic flow rate monitoring system.

    Science.gov (United States)

    Mantovani, Federico; Tagliaferri, Cristian

    2011-12-01

    A flow monitoring system based on a constant temperature hot-film anemometer is presented. The device has been designed to monitor a dispensing process of extremely low quantities of adhesive material. The monitoring device presented in this paper is useful in industrial applications where exact flow speed tracking is not needed, but reliability and tolerance to parameters variability are essential. During the design of the device, problems related to the physical characteristic of the calorimetric sensor, in particular its thermal capacitance, and to the periodic nature of the monitored flow have been taken into account and suitable solutions have been implemented. The schematic representation of the monitoring device together with the experimental results obtained by monitoring fluids with different physical characteristics are presented.

  16. Carbon Tetrachloride Flow and Transport in the Subsurface of the 216-Z-18 Crib and 216-Z-1A Tile Field at the Hanford Site: Multifluid Flow Simulations and Conceptual Model Update

    Energy Technology Data Exchange (ETDEWEB)

    Oostrom, Mart; Rockhold, Mark L.; Thorne, Paul D.; Last, George V.; Truex, Michael J.

    2006-10-31

    Carbon tetrachloride (CT) was discharged to the 216-Z-9, Z-1A, and Z-18 waste sites that are included in the 200-PW-1 Operable Unit in Hanford 200 West Area. Fluor Hanford, Inc. is conducting a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) remedial investigation/feasibility study (RI/FS) for the 200-PW-1 Operable Unit. As part of this overall effort, Pacific Northwest National Laboratory (PNNL) was contracted to improve the conceptual model of how CT is distributed in the Hanford 200 West Area subsurface through use of numerical flow and transport modeling. This work supports the U.S. Department of Energy's (DOE's) efforts to characterize the nature and distribution of CT in the 200 West Area and subsequently select an appropriate final remedy.

  17. CEM ultrasonic flow monitoring design, installation and certification results at the Salt River Project

    Energy Technology Data Exchange (ETDEWEB)

    Rihs, P.W. [Salt River Project, Saint Johns, AZ (United States). Coronado Generating Station

    1995-12-31

    This presentation will include Salt River Project`s design, installation, experiences and results using ultrasonic flow monitoring equipment for certification of continuous emissions monitoring systems. Flow Monitoring is the newest and has been the most controversial component of CEM systems. Experience in measuring flue gas volumetric flow prior to CEMs was very limited. There are currently three basic techniques used to measure gas flow: (1) thermal sensing using hotwire anemometer or thermal dispersion; (2) differential pressure (pitot tube and annubar); (3) acoustic using ultrasonic transducers. The Salt River Project (SRP) operates a variety of affected generating stations: coal, gas and oil. Ultrasonic flow monitoring technology was chosen for all affected generating stations which the author operates. SRP`s approach and reasoning for choosing ultrasonic systems will be discussed. A review of each generating station`s flow monitoring system will be presented. The presentation will include, but may not be limited to, the following: general facilities, description and schematics; physical installations, plan and section drawings; design considerations; results of flow monitors certification testing; and CEMs Project Manager`s conclusions.

  18. Salinity and Flow Monitoring in the San Francisco Bay Delta

    Science.gov (United States)

    This report describes the utility and approximate cost of expanding the salinity water quality monitoring network along the axis of the San Francisco Estuary from Suisun Bay to Rio Vista on the Sacramento River.

  19. Analysis of the metabolic utilization of carbon sources and potential functional diversity of the bacterial community in lab-scale horizontal subsurface-flow constructed wetlands.

    Science.gov (United States)

    Deng, Huanhuan; Ge, Liyun; Xu, Tan; Zhang, Minghua; Wang, Xuedong; Zhang, Yalei; Peng, Hong

    2011-01-01

    Microorganisms are an integral part of the biogeochemical processes in wetlands. To improve the performance of constructed wetlands, it is very important to know the metabolic properties and functional diversity of the microbial communities. The purpose of this study is to analyze the metabolic properties and functional diversity of the microbial community in a horizontal subsurface-flow constructed wetland (CW) in a laboratory study through the sole-carbon-source utilization profiles using Biolog-ECO microplates. The technique has advantages over traditional cell culture techniques, such as molecular-level techniques-RNA amplification, which are time-consuming, expensive, and only applicable to the small number of species that may be cultured. This CW was designed to treat rural eutrophic water in China, using the plant L. This study showed that the metabolic activities of upper front substrate microorganisms (UF) were greater than those of the lower back substrate microorganisms (LB) in the CW. Integrated areas under average well color development (AWCD) curves of substrate microorganisms in the UF were 131.9, 4.8, and 99.3% higher than in the lower front part (LF), the upper back part (UB), and the LB part of the CW, respectively. Principal components analysis showed significant differences in both community structure and metabolic utilization of carbon sources between substrate microorganisms from different sampling sites. Carbon source utilization of polymers, carbohydrates, carboxylic acids, and amino acids was higher in UF than in LF, but that of amines and phenolic compounds was very similar in UF and LF. The richness, evenness, and diversity of upper substrate microbial communities were significantly higher than those of lower substrate. The LF substrate microbial communities had lower evenness than the other sampling plots, and the lowest richness of substrate microbial community was found in the LB part of the CW.

  20. An efficient IMPES-based, shifting matrix algorithm to simulate two-phase, immiscible flow in porous media with application to CO 2 sequestration in the subsurface

    KAUST Repository

    Salama, Amgad

    2012-01-01

    The flow of two or more immiscible fluids in porous media is ubiquitous particularly in oil industry. This includes secondary and tertiary oil recovery, CO2 sequestration, etc. Accurate predictions of the development of these processes are important in estimating the benefits, e.g., in the form of increased oil extraction, when using certain technology. However, this accurate prediction depends to a large extent on two things; the first is related to our ability to correctly characterize the reservoir with all its complexities and the second depends on our ability to develop robust techniques that solve the governing equations efficiently and accurately. In this work, we introduce a new robust and efficient numerical technique to solving the governing conservation laws which govern the movement of two immiscible fluids in the subsurface. This work will be applied to the problem of CO2 sequestration in deep saline aquifer; however, it can also be extended to incorporate more cases. The traditional solution algorithms to this problem are based on discretizing the governing laws on a generic cell and then proceed to the other cells within loops. Therefore, it is expected that, calling and iterating these loops several times can take significant amount of CPU time. Furthermore, if this process is done using programming languages which require repeated interpretation each time a loop is called like Matlab, Python or the like, extremely longer time is expected particularly for larger systems. In this new algorithm, the solution is done for all the nodes at once and not within loops. The solution methodology involves manipulating all the variables as column vectors. Then using shifting matrices, these vectors are sifted in such a way that subtracting relevant vectors produces the corresponding difference algorithm. It has been found that this technique significantly reduces the amount of CPU times compared with traditional technique implemented within the framework of

  1. Subsurface Transport Over Reactive Multiphases (STORM): A general, coupled, nonisothermal multiphase flow, reactive transport, and porous medium alteration simulator, Version 2 user's guide

    Energy Technology Data Exchange (ETDEWEB)

    DH Bacon; MD White; BP McGrail

    2000-03-07

    The Hanford Site, in southeastern Washington State, has been used extensively to produce nuclear materials for the US strategic defense arsenal by the Department of Energy (DOE) and its predecessors, the US Atomic Energy Commission and the US Energy Research and Development Administration. A large inventory of radioactive and mixed waste has accumulated in 177 buried single- and double shell tanks. Liquid waste recovered from the tanks will be pretreated to separate the low-activity fraction from the high-level and transuranic wastes. Vitrification is the leading option for immobilization of these wastes, expected to produce approximately 550,000 metric tons of Low Activity Waste (LAW) glass. This total tonnage, based on nominal Na{sub 2}O oxide loading of 20% by weight, is destined for disposal in a near-surface facility. Before disposal of the immobilized waste can proceed, the DOE must approve a performance assessment, a document that described the impacts, if any, of the disposal facility on public health and environmental resources. Studies have shown that release rates of radionuclides from the glass waste form by reaction with water determine the impacts of the disposal action more than any other independent parameter. This report describes the latest accomplishments in the development of a computational tool, Subsurface Transport Over Reactive Multiphases (STORM), Version 2, a general, coupled non-isothermal multiphase flow and reactive transport simulator. The underlying mathematics in STORM describe the rate of change of the solute concentrations of pore water in a variably saturated, non-isothermal porous medium, and the alteration of waste forms, packaging materials, backfill, and host rocks.

  2. Numerical Simulation of Borehole Flow in Deep Monitor Wells, Pearl Harbor Aquifer, Oahu, Hawaii

    Science.gov (United States)

    Rotzoll, K.; Oki, D. S.; El-Kadi, A. I.

    2010-12-01

    Salinity profiles collected from uncased deep monitor wells are commonly used to monitor freshwater-lens thickness in coastal aquifers. However, vertical flow in these wells can cause the measured salinity to differ from salinity in the adjacent aquifer. Substantial borehole flow has been observed in uncased wells in the Pearl Harbor aquifer, Oahu, Hawaii. A numerical modeling approach, incorporating aquifer hydraulic characteristics and recharge rates representative of the Pearl Harbor aquifer, was used to evaluate the effects of borehole flow on measured salinity profiles from deep monitor wells. Borehole flow caused by vertical hydraulic gradients associated with the natural regional groundwater-flow system and local groundwater withdrawals was simulated. Model results were used to estimate differences between vertical salinity profiles in deep monitor wells and the adjacent aquifer in areas of downward, horizontal, and upward flow within the regional flow system—for cases with and without nearby pumped wells. Aquifer heterogeneity, represented in the model as layers of contrasting permeability, was incorporated in model scenarios. Results from this study provide insight into the magnitude of the differences between vertical salinity profiles from deep monitor wells and the salinity distributions in the aquifers. These insights are relevant and are critically needed for management and predictive modeling purposes.

  3. Longitudinal Monitoring of Hepatic Blood Flow before and after TIPS by Using 4D-Flow MR Imaging

    Science.gov (United States)

    Bannas, Peter; Roldán-Alzate, Alejandro; Johnson, Kevin M.; Woods, Michael A.; Ozkan, Orhan; Motosugi, Utaroh; Wieben, Oliver; Reeder, Scott B.; Kramer, Harald

    2016-01-01

    Purpose To demonstrate the feasibility of four-dimensional (4D)– flow magnetic resonance (MR) imaging for noninvasive longitudinal hemodynamic monitoring of hepatic blood flow before and after transjugular intrahepatic portosystemic shunt (TIPS) placement. Materials and Methods The institutional review board approved this prospective Health Insurance Portability and Accountability Act compliant study with written informed consent. Four-dimensional–flow MR imaging was performed in seven patients with portal hypertension and refractory ascites before and 2 and 12 weeks after TIPS placement by using a time-resolved three-dimensional radial phase-contrast acquisition. Flow and peak velocity measurements were obtained in the superior mesenteric vein (SMV), splenic vein (SV), portal vein (PV), and the TIPS. Flow volumes and peak velocities in each vessel, as well as the ratio of in-stent to PV flow, were compared before and after TIPS placement by using analysis of variance. Results Flow volumes significantly increased in the SMV (0.24 L/ min; 95% confidence interval [CI]: 0.07, 0.41), SV (0.31 L/min; 95% CI: 0.07, 0.54), and PV (0.88 L/min; 95% CI: 0.06, 1.70) after TIPS placement (all P .11). Ascites resolved in six of seven patients. In those with resolved ascites, the TIPS-to-PV flow ratio was 0.8 ± 6 0.2 and 0.9 ± 0.2 at the two post-TIPS time points, respectively, while the observed ratios were 4.6 and 4.3 in the patient with refractory ascites at the two post-TIPS time points, respectively. In this patient, 4D-flow MR imaging demonstrated arterio-portal-venous shunting, with draining into the TIPS. Conclusion Four-dimensional–flow MR imaging is feasible for noninvasive longitudinal hemodynamic monitoring of hepatic blood flow before and after TIPS placement. PMID:27171019

  4. 21 CFR 880.2420 - Electronic monitor for gravity flow infusion systems.

    Science.gov (United States)

    2010-04-01

    ... and equipment for signal amplification, conditioning, and display. (b) Classification. Class II... systems. 880.2420 Section 880.2420 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... and Personal Use Monitoring Devices § 880.2420 Electronic monitor for gravity flow infusion...

  5. Monitoring Debris Flows Using Spatial Filtering and Entropy Determination Approaches

    Directory of Open Access Journals (Sweden)

    Hung-Ming Kao

    2013-01-01

    Full Text Available We developed an automatic debris flow warning system in this study. The system uses a fixed video camera mounted over mountainous streams with a high risk for debris flows. The focus of this study is to develop an automatic algorithm for detecting debris flows with a low computational effort which can facilitate real-time implementation. The algorithm is based on a moving object detection technique to detect debris flow by comparing among video frames. Background subtraction is the kernel of the algorithm to reduce the computational effort, but non-rigid properties and color similarity of the object and the background color introduces some difficulties. Therefore, we used several spatial filtering approaches to increase the performance of the background subtraction. To increase the accuracy entropy is used with histogram analysis to identify whether a debris flow occurred. The modified background subtraction approach using spatial filtering and entropy determination is adopted to overcome the error in moving detection caused by non-rigid and similarities in color properties. The results of this study show that the approach described here can improve performance and also reduce the computational effort.

  6. 78 FR 65306 - Best Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams

    Science.gov (United States)

    2013-10-31

    ... AGENCY Best Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams AGENCY...: EPA is announcing a 30-day public comment period for the draft document titled, ``Best Practices for... Development. The report describes best practices for the deployment of continuous temperature and flow sensors...

  7. A multi-agent system for monitoring patient flow.

    Science.gov (United States)

    Rosati, Samanta; Tralli, Augusta; Balestra, Gabriella

    2013-01-01

    Patient flow within a healthcare facility may follow different and, sometimes, complicated paths. Each path phase is associated with the documentation of the activities carried out during it and may require the consultation of clinical guidelines, medical literature and the use of specific software and decision aid systems. In this study we present the design of a Patient Flow Management System (PFMS) based on Multi Agent Systems (MAS) methodology. System requirements were identified by means of process modeling tools and a MAS consisting of six agents was designed and is under construction. Its main goal is to support both the medical staff during the health care process and the hospital managers in assuring that all the required documentation is completed and available. Moreover, such a tool can be used for the assessment and comparison of different clinical pathways, in order to identify possible improvementsand the optimum patient flow.

  8. A study on the effects of different hydraulic loading rates (HLR) on pollutant removal efficiency of subsurface horizontal-flow constructed wetlands used for treatment of domestic wastewaters.

    Science.gov (United States)

    Çakir, Recep; Gidirislioglu, Ali; Çebi, Ulviye

    2015-12-01

    The research into the treatment of domestic wastewaters originating from Büyükdöllük village in Edirne Province was carried out over a 3 year experimental period. The wastewaters of the settlement were treated using a constructed wetland with subsurface horizontal flow, and the effects of different hydraulic loading levels on removal efficiency were studied. In order to achieve this goal, three equal chambers (ponds) of 300 m(2) each were constructed and planted with Phragmites australis. Each of the chambers was loaded with domestic wastewater with average flow discharge creating hydraulic loading rates of 0. m(3) day(-1) m(-2); 0.075 m(3) day(-1) m(-2) and 0.125 m(3) day(-1) m(-2), respectively. According to the results of the study, the inlet levels of the pollutant parameters with carbon origin in the water samples taken from the system entrance are high and the average values for three years are respectively: Biological Oxygen Demand, BOD5 -324.5 mg L(-1); Chemical Oxygen Demand, COD -484,0 mg L(-1); suspended solids (TSS) -147.3 mg L(-1) and Oil and Grease -0.123 mg L(-1). It was also determined that the removal rates of the system were closely dependent on the applied hydraulic loading levels and the highest removal rates of 64.9%, 62.5%, 86.3% and 80.34% for BOD5, COD, TSS and Oil and Grease, respectively, were determined in the pond with a hydraulic loading rate of 0.050 m(3) day(-1) m(-2). Lower removal of 57.9%, 55.5%, 81.4% and 74.5% for BOD5, COD, TSS and Oil and Grease were recorded in the pond with a hydraulic loading rate of 0.075 m(3) day(-1) m(-2); and these values were 49.1%, 47.8%, 70.9% and 62.1% for the pond with a hydraulic loading rate of 0.125 m(3) day(-1) m(-2). High removal rates were also recorded for the other investigated pollution parameters.

  9. Refractometric monitoring of dissolution and fluid flow with distributed feedback dye laser sensor

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Sørensen, Kristian Tølbøl; Gade, Carsten

    2015-01-01

    Monitoring the dissolution of solid material in liquids and monitoring of fluid flow is of significant interest for applications in chemistry, food production, medicine, and especially in the fields of microfluidics and lab on a chip. Here, real-time refractometric monitoring of dissolution...... and fast fluid flow with DFB dye laser sensors with an optical imaging spectroscopy setup is presented. The dye laser sensors provide both low detection limits and high spatial resolution. It is demonstrated how the materials NaCl, sucrose, and bovine serum albumin show characteristic dissolution patterns...

  10. Numerical model simulating water flow and contaminant and sediment transport in watershed systems of 1-d stream-river network, 2-d overland regime, and 3-d subsurface media (WASH123d: version 1.0). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.; Cheng, H.; Cheng, J.; Lin, H.C.; Martin, W.D.

    1998-07-01

    This report presents the development of a numerical model simulating water flow and contaminant and sediment transport in watershed systems of one-dimensional river/stream network, two-dimensional overland regime, and three-dimensional subsurface media. The model is composed of two modules: flow and transport. Three options are provided in modeling the flow module in river/ stream network and overland regime: the kinematic wave approach, diffusion wave approach, and dynamic wave approach. The kinematic and diffusion wave approaches are known to be numerically robust in terms of numerical convergency and stability; i.e., they can generate convergent and stable simulations over a wide range of ground surface slopes in the entire watershed. The question is the accuracy of these simulations. The kinematic wave approach usually produces accurate solutions only over the region of steep slopes. The diffusion wave approach normally gives accurate solutions over the region of mild to steep slopes. However, neither approach has the ability to yield accurate solutions over the region of small slopes, in which the inertial forces are no longer negligible compared to the gravitational forces. The kinematic wave approach cannot address the problems of backwater effects. On the other hand, a dynamic wave approach, having included all forces, can theoretically have the potential to generate accurate simulations over all ranges of slopes in a watershed. The subsurface flow is described by Richard`s equation where water flow through saturated-unsaturated porous media is accounted for.

  11. Refractometric monitoring of dissolution and fluid flow with distributed feedback dye laser sensor

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Sørensen, Kristian Tølbøl; Gade, Carsten;

    2015-01-01

    and fast fluid flow with DFB dye laser sensors with an optical imaging spectroscopy setup is presented. The dye laser sensors provide both low detection limits and high spatial resolution. It is demonstrated how the materials NaCl, sucrose, and bovine serum albumin show characteristic dissolution patterns......Monitoring the dissolution of solid material in liquids and monitoring of fluid flow is of significant interest for applications in chemistry, food production, medicine, and especially in the fields of microfluidics and lab on a chip. Here, real-time refractometric monitoring of dissolution....... The unique feature of the presented method is a high frame rate of up to 20 Hz, which is proven to enable the monitoring of fast flow of a sucrose solution jet into pure water. (C) 2015 Optical Society of America...

  12. Methods for monitoring heat flow intensity in the blast furnace wall

    Directory of Open Access Journals (Sweden)

    L'. Dorčák

    2010-04-01

    Full Text Available In this paper we present the main features of an online system for real-time monitoring of the bottom part of the blast furnace. Firstly, monitoring concerns the furnace walls and furnace bottom temperatures measurement and their visualization. Secondly, monitored are the heat flows of the furnace walls and furnace bottom. In the case of two measured temperatures, the heat flow is calculated using multi-layer implicit difference scheme and in the case of only one measured temperature, the heat flow is calculated using a method based on application of fractional-order derivatives. Thirdly, monitored is the theoretical temperature of the blast furnace combustion process in the area of tuyeres.

  13. Refractometric monitoring of dissolution and fluid flow with distributed feedback dye laser sensor.

    Science.gov (United States)

    Vannahme, Christoph; Sørensen, Kristian Tølbøl; Gade, Carsten; Dufva, Martin; Kristensen, Anders

    2015-03-09

    Monitoring the dissolution of solid material in liquids and monitoring of fluid flow is of significant interest for applications in chemistry, food production, medicine, and especially in the fields of microfluidics and lab on a chip. Here, real-time refractometric monitoring of dissolution and fast fluid flow with DFB dye laser sensors with an optical imaging spectroscopy setup is presented. The dye laser sensors provide both low detection limits and high spatial resolution. It is demonstrated how the materials NaCl, sucrose, and bovine serum albumin show characteristic dissolution patterns. The unique feature of the presented method is a high frame rate of up to 20 Hz, which is proven to enable the monitoring of fast flow of a sucrose solution jet into pure water.

  14. A Markov Chain Monte Carlo Inversion Approach for Assessing Reactive Chemistry Along a Flow Path with Application to Subsurface CO2 Injection

    Science.gov (United States)

    McNab, W. W.; Ramirez, A. L.; Johnson, J.

    2011-12-01

    A Markov Chain Monte Carlo (MCMC) modeling approach has been developed to identify the distribution of key reactive mineral phases along a flow path between a CO2 injector well and a monitor well at the Weyburn-Midale field in Saskatchewan. The method entailed postulating a spatially-correlated mineral distribution, consisting of calcite, dolomite, anhydrite, and K-feldspar, with specified volume fractions and intrinsic dissolution rates, in contact with an ambient brine composition along a 1-D flow path. Multiple forward reactive transport simulations for the column were run (using PHREEQC for this particular application), with simulated changes in brine chemistry compared with controlled test problem output or real field data. A composite likelihood function was calculated for a set of geochemical parameters consisting of pH and the concentrations of Ca2+, Mg2+, and Si that serves as potential indicators of dissolution reactions along the flow path. New realizations were proposed by replacing a small contiguous section of the column with a new distribution of minerals, but one which was still spatially correlated with the remainder of the column. Proposed realizations were accepted when the ratio of the composite likelihood function value to that of the prior proposal was greater than that of a random number selected from a uniform distribution between 0 and 1 (the well-known Metropolis-Hastings acceptance criteria). If a proposal was accepted, the modified mineral distribution served as the basis for a new distribution, otherwise the modification was rejected as a non-improvement. Application of the inverse modeling approach to a synthetic problem demonstrated nearly complete recovery of a specified initial mineral distribution (i.e., "synthetic truth") along the flow path, provided that parameter data were utilized across the entire column. Partial recovery of the synthetic truth was still achievable as the amount of data available for inversion were reduced to

  15. Nonintrusive fast response oxygen monitoring system for high temperature flows

    Science.gov (United States)

    Oh, Daniel B.; Stanton, Alan C.

    1993-01-01

    A new technique has been developed for nonintrusive in situ measurement of oxygen concentration, gas temperature, and flow velocity of the test media in hypersonic wind tunnels. It is based on absorption of near-infrared radiation from inexpensive GaAlAs laser diodes used in optoelectronics industry. It is designed for simultaneous measurements along multiple lines of sight accessed by fiber optics. Molecular oxygen concentration is measured from the magnitude of absorption signals; rotational gas temperature is measured from the intensity ratio of two oxygen absorption lines; and the flow velocity is measured from the Doppler shift of the absorption line positions. This report describes the results of an extensive series of tests of the prototype instrument in laboratory flames emphasizing assessment of the instruments capabilities for quantitative measurement of O2 concentration (mole fraction) and gas temperature.

  16. Noninvasive tomographic and velocimetric monitoring of multiphase flows

    Energy Technology Data Exchange (ETDEWEB)

    Chaouki, J. [Ecole Polytechnique de Montreal, Quebec (Canada). Dept. of Chemical Engineering; Larachi, F. [Laval Univ., Quebec (Canada); Dudukovic, M.P. [Washington Univ., St. Louis, MO (United States). Chemical Reaction Engineering Lab.

    1997-11-01

    A condensed review of recent advances accomplished in the development and the applications of noninvasive tomographic and velocimetric measurement techniques to multiphase flows and systems is presented. In recent years utilization of such noninvasive techniques has become widespread in many engineering disciplines that deal with systems involving two immiscible phases or more. Tomography provides concentration, holdup, or 2D or 3D density distribution of at least one component of the multiphase system, whereas velocimetry provides the dynamic features of the phase of interest such as the flow pattern, the velocity field, the 2D or 3D instantaneous movements, etc. The following review is divided into two parts. The first part summarizes progress and developments in flow imaging techniques using {gamma}-ray and X-ray transmission tomography; X-ray radiography; neutron transmission tomography and radiography; positron emission tomography; X-ray diffraction tomography; nuclear magnetic resonance imaging; electrical capacitance tomography; optical tomography; microwave tomography; and ultrasonic tomography. The second part of the review summarizes progress and developments in the following velocimetry techniques: positron emission particle tracking; radioactive particle tracking; cinematography; laser-Doppler anemometry; particle image velocimetry; and fluorescence particle image velocimetry. The basic principles of tomography and velocimetry techniques are outlined, along with advantages and limitations inherent to each technique. The hydrodynamic and structural information yielded by these techniques is illustrated through a literature survey on their successful applications to the study of multiphase systems in such fields as particulate solids processes, fluidization engineering, porous media, pipe flows, transport within packed beds and sparged reactors, etc.

  17. Monitoring drilling mud composition using flowing liquid junction electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, R.; Fletcher, P.; Vercaemer, C.

    1990-06-27

    The concentration of a chosen ionic component of a drilling mud is determined from the potential difference between an ion selective electrode, selective to the component and a reference electrode, the reference electrode being connected to the mud by a liquid junction through which reference electrolyte flows from the electrode to the mud. The system avoids errors due to undesirable interactions between the mud and the reference electrode materials. (author).

  18. Apparatus and method for acoustic monitoring of steam quality and flow

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Dipen N.; Pantea, Cristian

    2016-09-13

    An apparatus and method for noninvasively monitoring steam quality and flow and in pipes or conduits bearing flowing steam, are described. By measuring the acoustic vibrations generated in steam-carrying conduits by the flowing steam either by direct contact with the pipe or remotely thereto, converting the measured acoustic vibrations into a frequency spectrum characteristic of the natural resonance vibrations of the pipe, and monitoring the amplitude and/or the frequency of one or more chosen resonance frequencies, changes in the steam quality in the pipe are determined. The steam flow rate and the steam quality are inversely related, and changes in the steam flow rate are calculated from changes in the steam quality once suitable calibration curves are obtained.

  19. Groundwater Flow Field Distortion by Monitoring Wells and Passive Flux Meters.

    Science.gov (United States)

    Verreydt, G; Bronders, J; Van Keer, I; Diels, L; Vanderauwera, P

    2015-01-01

    Due to differences in hydraulic conductivity and effects of well construction geometry, groundwater lateral flow through a monitoring well typically differs from groundwater flow in the surrounding aquifer. These differences must be well understood in order to apply passive measuring techniques, such as passive flux meters (PFMs) used for the measurement of groundwater and contaminant mass fluxes. To understand these differences, lab flow tank experiments were performed to evaluate the influences of the well screen, the surrounding filter pack and the presence of a PFM on the natural groundwater flux through a monitoring well. The results were compared with analytical calculations of flow field distortion based on the potential theory of Drost et al. (1968). Measured well flow field distortion factors were found to be lower than calculated flow field distortion factors, while measured PFM flow field distortion factors were comparable to the calculated ones. However, this latter is not the case for all conditions. The slotted geometry of the well screen seems to make a correct analytical calculation challenging for conditions where flow field deviation occurs, because the potential theory assumes a uniform flow field. Finally, plots of the functional relationships of the distortion of the flow field with the hydraulic conductivities of the filter screen, surrounding filter pack and corresponding radii make it possible to design well construction to optimally function during PFM applications.

  20. 潜流人工湿地除氮的生态动力学模拟%Simulation of Nitrogen Removal in Subsurface Flow Constructed Wetland

    Institute of Scientific and Technical Information of China (English)

    刘晓娜; 丁爱中; 程莉蓉; 郑蕾; 左丽丽; 陈海英

    2011-01-01

    对某潜流人工湿地建立生态动力学模型,利用MATLAB编程模拟湿地中氮素的迁移转化过程,确定了主要除氮机制.模拟结果显示,该模型能较好地模拟出水中有机氮、氨氮和硝态氮浓度的变化趋势和范围.进一步进行氮素质量平衡分析可知,该人工湿地的主要除氮机制为硝化、反硝化和植物吸收,有机氮、氨氮和硝态氮的总去除率为60.53%,其中反硝化过程去除43.10%,植物吸收去除13.98%,沉淀去除3.45%.%As a new technology of sewage treatment, constructed wetland has been accepted in many countries because of its high nitrogenremoval efficiency, low cost, simple operation, landscaping and so on.However, it is difficult to quantify the different nitrogen-removal processes, thus unable to attribute nitrogen-removal rate to substrate, plants and microorganism without mathematical model.We established an eco-dynamic model for a subsurface flow constructed wetland to investigate and quantify nitrogen transfer processes between water, matrix and plant.In the model, mineralization, nitrification, denitrification, plant take-up, microbial assimilation, precipitation, regeneration and decay processes were considered.Mass balance method is the core in building the mathematical model.The state variables in the model are aqueous species nitrogen (Org-N, NH4-N, NO3-N) nitrogen in matrix (N-gravel) and nitrogen in plan (N-Plants).MATLAB programming was used to solve the mathematical model.The key mechanism of nitrogen removal was identified based on the simulation results.It was showed that the calibrated model could generally reproduce the patterns of concentration variations for organic nitrogen, NH4-N and NO3-N.Further mass balance analysis showed that the major nitrogen removal mechanisms in the constructed wetland were nitrification, denitrification and plant uptake.The total removal efficiency for organic nitrogen, NH4-N and NO3-N was 60.53%, of which denitrification

  1. The Effectiveness of Organic Pollutants Removal in Constructed Wetland with Horizontal Sub-Surface Flow / Efektywność Usuwania Zanieczyszczeń Organicznych W Oczyszczalni Hydrofitowej

    Science.gov (United States)

    Jakubaszek, Anita; Sadecka, Zofia

    2015-03-01

    This paper presents the results of the research work related to the removal efficiency from wastewater organic pollutants and suspended solids at HSSF (horizontal subsurface flow) constructed wetland. The average effectiveness defined as loss of value COD in wastewater has reached 77%, for BOD5 - 80% and TOC - 82%. The effect of seasonal temperature changes and the period of plant vegetation and rest on the effectiveness of wastewater treatment were also analyzed. The results of the presented research showed a decrease in the efficiency of removing organic pollutants from wastewater and suspended solids in the autumn and winter. During the vegetation the object in Małyszyn has been characterized by the effectiveness of wastewater treatment at the level of 78% for COD, 82% for BOD5, and in the non-vegetation period the effectiveness has decreased up to 75% for COD and 74% for BOD5. During the plants growth the total suspension was removed in 88%, whereas during the plants rest efficiency of removing lowered to 69%. W pracy przedstawiono wyniki badań dotyczące efektywności usuwania ze ścieków zanieczyszczeń organicznych w oczyszczalni hydrofitowej. Średnia skuteczność oczyszczania wyrażona jako obniżenie wartości ChZT w ściekach była na poziomie 77%, dla BZT5 80%, a dla OWO 82%. Analizowano również wpływ sezonowych zmian temperatury oraz okresu wegetacji i spoczynku roślin na skuteczność oczyszczania ścieków. Wyniki badań wykazały obniżenie efektywności usuwania zanieczyszczeń organicznych ze ścieków wyrażonych przez ChZT i BZT5 oraz zawiesiny ogólnej w okresie jesienno-zimowym. W okresie wegetacyjnym obiekt w Małyszynie charakteryzował się efektywnością oczyszczania ścieków na poziomie: 78% dla ChZT, 82% dla BZT5, a w sezonie pozawegetacyjnym skuteczność uległa obniżeniu do 75% w przypadku ChZT oraz 74% dla BZT5. Zawiesina ogólna w okresie wegetacji trzciny usuwana była w 88%, a w okresie powegetacyjnym w 69%.

  2. Reconstruction of Solar Subsurfaces by Local Helioseismology

    CERN Document Server

    Kosovichev, Alexander G

    2016-01-01

    Local helioseismology has opened new frontiers in our quest for understanding of the internal dynamics and dynamo on the Sun. Local helioseismology reconstructs subsurface structures and flows by extracting coherent signals of acoustic waves traveling through the interior and carrying information about subsurface perturbations and flows, from stochastic oscillations observed on the surface. The initial analysis of the subsurface flow maps reconstructed from the 5 years of SDO/HMI data by time-distance helioseismology reveals the great potential for studying and understanding of the dynamics of the quiet Sun and active regions, and the evolution with the solar cycle. In particular, our results show that the emergence and evolution of active regions are accompanied by multi-scale flow patterns, and that the meridional flows display the North-South asymmetry closely correlating with the magnetic activity. The latitudinal variations of the meridional circulation speed, which are probably related to the large-scal...

  3. Mucosal blood flow measurements using laser Doppler perfusion monitoring

    Institute of Scientific and Technical Information of China (English)

    Dag Arne Lihaug Hoff; Hans Gregersen; Jan Gunnar Hatlebakk

    2009-01-01

    Perfusion of individual tissues is a basic physiological process that is necessary to sustain oxygenation and nutrition at a cellular level. Ischemia, or the insufficiency of perfusion, is a common mechanism for tissue death or degeneration, and at a lower threshold, a mechanism for the generation of sensory signalling including pain. It is of considerable interest to study perfusion of peripheral abdominal tissues in a variety of circumstances. Microvascular disease of the abdominal organs has been implicated in the pathogenesis of a variety of disorders, including peptic ulcer disease, inflammatory bowel disease and chest pain. The basic principle of laser Doppler perfusion monitoring (LDPM) is to analyze changes in the spectrum of light reflected from tissues as a response to a beam of monochromatic laser light emitted. It reflects the total local microcirculatory blood perfusion, including perfusion in capillaries, arterioles, venules and shunts. During the last 20-25 years, numerous studies have been performed in different parts of the gastrointestinal (GI) tract using LDPM. In recent years we have developed a multi-modal catheter device which includes a laser Doppler probe, with the intent primarily to investigate patients suffering from functional chest pain of presumed oesophageal origin. Preliminary studies show the feasibility of incorporating LDPM into such catheters for performing physiological studies in the GI tract. LDPM has emerged as a research and clinical tool in preference to other methods; but, it is important to be aware of its limitations and account for them when reporting results.

  4. Investigating controls on debris-flow initiation and surge frequency at Chalk Cliffs, USA: initial results from monitoring and modeling

    Science.gov (United States)

    Kean, J. W.; McCoy, S. W.; Tucker, G. E.; Staley, D. M.; Coe, J. A.

    2012-04-01

    Recent monitoring of a small (0.3 km2) bedrock-dominated catchment in central Colorado, USA, has revealed distinct differences in debris-flow surge dynamics relative to rainfall intensity. Moderate bursts of rainfall (15-40 mm/hr) typically trigger a set of coarse-grained surges with depths that can exceed 1.0 m. High-intensity bursts of rainfall (40-150 mm/hr), in contrast, often generate only a single moderate-amplitude coarse-grained surge (> 0.5 m depth), followed by several minutes of water-rich flow having comparable or greater peak depth. In both cases, debris flows are observed within minutes of rain bursts due to the rapid concentration of runoff from bedrock cliffs to channels loaded with sediment from dry ravel and rockfall. Video observations have shown that the runoff can initiate debris flows both at a steep (~40 degree) bedrock-colluvium interface, and in a lower gradient (~15 degree) section of channel. This latter style of initiation, which has only been observed at moderate rainfall intensity, involves the formation and failure of a highly porous sediment dam created by bedload transport. We speculate that this process may be responsible for the creation of the consistent surge patterns we observe with moderate intensity rainfall, and may explain the relative lack of granular surges with high-intensity rainfall. To investigate this possibility, we have developed a simple one-dimensional morphodynamic model of the formation and failure of sediment dams in an undulating bedrock channel filled with loose bed sediment. The model consists of a coupled surface-subsurface water flow model, which is used to drive bed-sediment topographic adjustments based on the mathematical divergence of the sediment transport rate. Under certain topographic and water-flow conditions, the shear stress in a section of the channel can fall below the critical shear stress, resulting in local deposition of sediment. Consistent with field observations, the modeled deposit

  5. Topographic effects on SP anomaly caused subsurface fluid flow. Numerical approach; Chikasui ryudo ni tomonau shizen den`i ijo ni taisuru chikei no koka. Suchi modeling ni yoru approach

    Energy Technology Data Exchange (ETDEWEB)

    Yasukawa, K. [Geological Survey of Japan, Tsukuba (Japan); Mogi, T. [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1998-02-01

    Self-Potential (SP) anomaly at the ground surface caused by subsurface fluid flow is numerically calculated for two-dimensional models using a simulation code PTSP to investigate the topographic effects on the SP profile. The result shows that the negative SP anomaly generally seen in higher elevation can be explained as a result of topographic effects on the near surface fluid flow system for cases of homogeneous earth. However, heterogeneous permeability distribution possibly changes the fluid flow pattern and its derived SP profile. Heterogeneity in electrical resistivity and cross-coupling conductivity also affects on the SP pattern, causing the shift of peak anomaly location. Therefore, a numerical approach applying hydrogeological and physical property distributions is invaluable for detailed interpretation of SP survey data. 19 refs., 8 figs.

  6. Transport of Chemical Vapors from Subsurface Sources to Atmosphere as Affected by Shallow Subsurface and Atmospheric Conditions

    Science.gov (United States)

    Rice, A. K.; Smits, K. M.; Hosken, K.; Schulte, P.; Illangasekare, T. H.

    2012-12-01

    Understanding the movement and modeling of chemical vapor through unsaturated soil in the shallow subsurface when subjected to natural atmospheric thermal and mass flux boundary conditions at the land surface is of importance to applications such as landmine detection and vapor intrusion into subsurface structures. New, advanced technologies exist to sense chemical signatures at the land/atmosphere interface, but interpretation of these sensor signals to make assessment of source conditions remains a challenge. Chemical signatures are subject to numerous interactions while migrating through the unsaturated soil environment, attenuating signal strength and masking contaminant source conditions. The dominant process governing movement of gases through porous media is often assumed to be Fickian diffusion through the air phase with minimal or no quantification of other processes contributing to vapor migration, such as thermal diffusion, convective gas flow due to the displacement of air, expansion/contraction of air due to temperature changes, temporal and spatial variations of soil moisture and fluctuations in atmospheric pressure. Soil water evaporation and interfacial mass transfer add to the complexity of the system. The goal of this work is to perform controlled experiments under transient conditions of soil moisture, temperature and wind at the land/atmosphere interface and use the resulting dataset to test existing theories on subsurface gas flow and iterate between numerical modeling efforts and experimental data. Ultimately, we aim to update conceptual models of shallow subsurface vapor transport to include conditionally significant transport processes and inform placement of mobile sensors and/or networks. We have developed a two-dimensional tank apparatus equipped with a network of sensors and a flow-through head space for simulation of the atmospheric interface. A detailed matrix of realistic atmospheric boundary conditions was applied in a series of

  7. Full-field speckle correlation technique as applied to blood flow monitoring

    Science.gov (United States)

    Vilensky, M. A.; Agafonov, D. N.; Timoshina, P. A.; Shipovskaya, O. V.; Zimnyakov, D. A.; Tuchin, V. V.; Novikov, P. A.

    2011-03-01

    The results of experimental study of monitoring the microcirculation in tissue superficial layers of the internal organs at gastro-duodenal hemorrhage with the use of laser speckles contrast analysis technique are presented. The microcirculation monitoring was provided in the course of the laparotomy of rat abdominal cavity in the real time. Microscopic hemodynamics was analyzed for small intestine and stomach under different conditions (normal state, provoked ischemia, administration of vasodilative agents such as papaverine, lidocaine). The prospects and problems of internal monitoring of micro-vascular flow in clinical conditions are discussed.

  8. Ab inito based model for subsurface flow and wett-ability alterations at reservoir condition for variation in ionic composition for carbonates

    Science.gov (United States)

    Hara Chakravarty, Krishna; Thomsan, Kaj

    2013-04-01

    Through both field and laboratory studies it has been well established that wett-ability and flow rate in carbonate and sandstone reservoirs during water flooding is dictated by the sub-surface chemistry connected to stability of the water film amidst the oil phase and the rock surface, but there is no mathematical model to explain the flow rate and wett-ability mechanism on insertion of a low saline water in the rock system and its interaction with the hydrocarbons. Here, a model for calculating the feasible surface reactions has been developed based on free energy profiles of the different combinations of water, metal (Calcium, strontium and Magnesium) ions and hydrocarbons over a temperature regime of 273 K to 373 K .The approach uses Density Functional Theory based Local Density Approximation on molecular dynamic simulation using standard plane wave pseudopotential scheme. Herein we observe a two shell model during the interaction of water molecule with free energy of -2.8 and -2.5 kJ/mol at 2.4 and 4.2 Å heights from the calcite surface. Mg2+-water complex also retains a two layer model, while Ca2+ and Sr2+ metal ion-water complex show one major layer model of the free energy profile. The metal ion-water cluster adsorbs as an inner sphere complex directly above a surface carbonate group at a height of 3.9, 4.1, and 4.2 Å for calcium, strontium and magnesium respectively at a temperature of 273 K ,which is almost at the same height of the outer shell(4.2 Å) of bulk water profile and thus provides a local energy well for interaction among the complexes. Moreover at this height Mg2+ shows significantly more stability than water or other metal ion complex and it retains a similar pattern of energy profile at temperatures upto 373 K while outer shells loose their structure at higher temperatures in other metal ion complexes. A series of calculation were conducted to achieve the most stable polar hydrocarbon-metal ion-water complex for each metal individually .A

  9. System-focused environmental flow regime prescription, monitoring and adaptive management

    Science.gov (United States)

    Hetherington, David; Lexartza Artza, Irantzu

    2016-04-01

    that more peripheral influencing factors should be given serious consideration when developing environmental flow regimes. These factors could include the development of ice, non-fluvial geomorphic processes such as landslides, connectivity with groundwater and provision for local cottage industries. Even with a thorough appreciation of the holistic system, the value of detailed environmental monitoring and adaptive management plans cannot be underestimated as a means of further managing risk and uncertainty in complex systems. It is suggested that by taking a more holistic and system-focused approach to environmental flow definition, that environmental flow regimes can be tailored to the specificity and complexity of any given location. By improving the way that environmental flow regimes and associated physical mitigation are prescribed, monitored and managed it should be possible to develop more sustainable forms of energy production whilst minimising environmental harm as far as possible.

  10. Debris flow monitoring in the Acquabona watershed on the Dolomites (Italian Alps)

    Science.gov (United States)

    Berti, M.; Genevois, R.; LaHusen, R.; Simoni, A.; Tecca, P.R.

    2000-01-01

    In 1997 a field monitoring system was installed in Acquabona Creek in the Dolomites (Eastern Italian Alps) to observe the hydrologic conditions for debris flow occurrence and some dynamic properties of debris flow. The monitoring system consists of three remote stations: an upper one located at the head of a deeply-incised channel and two others located downstream. The system is equipped with sensors for measuring rainfall, pore pressures in the mobile channel bottom, ground vibrations, debris flow depth, total normal stress and fluid pore-pressure at the base of the flow. Two video cameras record events at the upper channel station and one video is installed at the lowermost station. During summer 1998, three debris flows (volumes from less than 1000 m3 up to 9000 m3) occurred at Acquabona. The following results were obtained from a preliminary analysis of the data: 1) All of the flows were triggered by rainfalls of less than 1 hour duration, with peak rainfall intensities ranging from 4.8 to 14.7 mm / 10 minute. 2) Debris flows initiated in several reaches of the channel, including the head of the talus slope. 3) The initial surges of the mature flows had a higher solid concentration and a lower velocity (up to 4 m/s) than succeeding, more dilute surges (more than 7 m/s). 4) Total normal stress and pore fluid pressures measured at the base of the flow (mean depth about 1.1 m) were similar (about 15 kPa), indicating a completely liquefied flow. 5) Peak flows entrained debris at a rate of about 6 m3/m of channel length and channel bed scouring was proportional to the local slope gradient and was still evident in the lower channel where the slope was 7??. ?? 2000 Elsevier Science Ltd. All rights reserved.

  11. Subsurface flow and transport of organic chemicals: an assessment of current modeling capability and priority directions for future research (1987-1995)

    Energy Technology Data Exchange (ETDEWEB)

    Streile, G.P.; Simmons, C.S.

    1986-09-01

    Theoretical and computer modeling capability for assessing the subsurface movement and fate of organic contaminants in groundwater was examined. Hence, this study is particularly concerned with energy-related, organic compounds that could enter a subsurface environment and move as components of a liquid phase separate from groundwater. The migration of organic chemicals that exist in an aqueous dissolved state is certainly a part of this more general scenario. However, modeling of the transport of chemicals in aqueous solution has already been the subject of several reviews. Hence, this study emphasizes the multiphase scenario. This study was initiated to focus on the important physicochemical processes that control the behavior of organic substances in groundwater systems, to evaluate the theory describing these processes, and to search for and evaluate computer codes that implement models that correctly conceptualize the problem situation. This study is not a code inventory, and no effort was made to identify every available code capable of representing a particular process.

  12. Subsurface stormflow modeling with sensitivity analysis using a Latin-hypercube sampling technique

    Energy Technology Data Exchange (ETDEWEB)

    Gwo, J.P.; Toran, L.E.; Morris, M.D. [Oak Ridge National Lab., TN (United States); Wilson, G.V. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Plant and Soil Science

    1994-09-01

    Subsurface stormflow, because of its dynamic and nonlinear features, has been a very challenging process in both field experiments and modeling studies. The disposal of wastes in subsurface stormflow and vadose zones at Oak Ridge National Laboratory, however, demands more effort to characterize these flow zones and to study their dynamic flow processes. Field data and modeling studies for these flow zones are relatively scarce, and the effect of engineering designs on the flow processes is poorly understood. On the basis of a risk assessment framework and a conceptual model for the Oak Ridge Reservation area, numerical models of a proposed waste disposal site were built, and a Latin-hypercube simulation technique was used to study the uncertainty of model parameters. Four scenarios, with three engineering designs, were simulated, and the effectiveness of the engineering designs was evaluated. Sensitivity analysis of model parameters suggested that hydraulic conductivity was the most influential parameter. However, local heterogeneities may alter flow patterns and result in complex recharge and discharge patterns. Hydraulic conductivity, therefore, may not be used as the only reference for subsurface flow monitoring and engineering operations. Neither of the two engineering designs, capping and French drains, was found to be effective in hydrologically isolating downslope waste trenches. However, pressure head contours indicated that combinations of both designs may prove more effective than either one alone.

  13. Thirty-one years of debris-flow observation and monitoring near La Honda, California, USA

    Science.gov (United States)

    Wieczorek, G.F.; Wilson, R.C.; Ellen, S.D.; Reid, M.E.; Jayko, A.S.

    2007-01-01

    From 1975 until 2006,18 intense storms triggered at least 248 debris flows within 10 km2 northwest of the town of La Honda within the Santa Cruz Mountains, California. In addition to mapping debris flows and other types of landslides, studies included soil sampling and geologic mapping, piezometric and tensiometer monitoring, and rainfall measurement and recording. From 1985 until 1995, a system with radio telemetered rain gages and piezometers within the La Honda region was used for issuing six debris-flow warnings within the San Francisco Bay region through the NOAA ALERT system. Depending upon the relative intensity of rainfall during storms, debris flows were generated from deep slumps, shallow slumps, shallow slides in colluvium and shallow slides over bedrock. Analysis shows the storms with abundant antecedent rainfall followed by several days of steady heavy intense rainfall triggered the most abundant debris flows. ?? 2007 millpress.

  14. A New Submersible Imaging-in-flow Instrument to Monitor Nano- and Microplankton: Imaging FlowCytobot

    Science.gov (United States)

    Olson, R. J.; Sosik, H. M.; Shalapyonok, A.

    2004-12-01

    Understanding of how coastal plankton communities are regulated has traditionally been limited by undersampling, but cabled observatories now provide opportunities to deploy submersible sensors that have high power and data transmission requirements. We have developed an in situ instrument to carry out high-resolution, long term monitoring of phytoplankton and microzooplankton in the size range 10 to100 micrometers, to be deployed at cabled research facilities such as the Martha's Vineyard Coastal Observatory (MVCO). The new instrument is designed to complement FlowCytobot, a submersible flow cytometer currently deployed at MVCO that uses fluorescence and light scattering signals from a laser beam to characterize the smallest phytoplankton cells (less than 10 micrometers). Imaging FlowCytobot uses a combination of flow cytometric and video technology to capture images of organisms for identification and to measure chlorophyll fluorescence associated with each image. Images will be classified using neural net software, while the measurements of chlorophyll fluorescence will allow us to discriminate heterotrophic from phototrophic cells. The new instrument, like the original FlowCytobot is autonomous but remotely programmable. It utilizes a computer controlled syringe pump and distribution valve that allows periodic anti-fouling treatment and analysis of standard beads. Samples are analyzed continuously (0.25 to 2.5 ml per min) and data is sent over a fiber optic link to a remote computer for analysis. Preliminary results indicate that we can detect cells as small as 5 micrometers and discriminate several taxa of diatoms and dinoflagellates.

  15. Blend Down Monitoring System Fissile Mass Flow Monitor Implementation at the ElectroChemical Plant, Zelenogorsk, Russia

    Energy Technology Data Exchange (ETDEWEB)

    Uckan, T.

    2005-11-11

    The implementation plans and preparations for installation of the Fissile Mass Flow Monitor (FMFM) equipment at the ElectroChemical Plant (ECP), Zelenogorsk, Russia, are presented in this report. The FMFM, developed at Oak Ridge National Laboratory, is part of the Blend Down Monitoring System (BDMS), developed for the U.S. Department of Energy Highly Enriched Uranium (HEU) Transparency Implementation Program. The BDMS provides confidence to the United States that the Russian nuclear facilities supplying the lower-assay ({approx}4%) product low enriched uranium (P-LEU) to the United States from down-blended weapons-grade HEU are meeting the nonproliferation goals of the government-to-government HEU Purchase Agreement, signed between the Russian Federation and the United States in 1993. The first BDMS has been operational at Ural Electrochemical Integrated Plant, Novouralsk, since February 1999 and is successfully providing HEU transparency data to the United States. The second BDMS was installed at ECP in February 2003. The FMFM makes use of a set of thermalized californium-252 ({sup 252}Cf) spontaneous neutron sources for a modulated fission activation of the UF{sub 6} gas stream for measuring the {sup 235}U fissile mass flow rate. To do this, the FMFM measures the transport time of the fission fragments created from the fission activation process under the modulated source to the downstream detectors by detecting the delayed gamma rays from the fission fragments. The FMFM provides unattended, nonintrusive measurements of the {sup 235}U mass flow in the HEU, LEU blend stock, and P-LEU process legs. The FMFM also provides the traceability of the HEU flow to the product process leg. This report documents the technical installation requirements and the expected operational characteristics of the ECP FMFM.

  16. The Monitoring of River Flows and the Management of Flood Hazards using UAVs

    Science.gov (United States)

    Verosub, K. L.

    2015-12-01

    The increasing occurrence of extreme precipitation events as well as severe droughts, coupled with greater and greater human occupation of flood plains, makes increased monitoring of flows in rivers an important component of assessing the potential for water-related natural disasters as well as responding to them when they do occur. Unfortunately, this increasing need comes at a time when funding for monitoring activities is generally decreasing. In the United States, for example, gauging stations with daily flow records going back several decades or even a hundred years have been abandoned, and new stations in critical areas have not even been established. A methodology based on periodic UAV-based imaging of an entire river offers the prospect of obtaining inexpensive, real-time, high-resolution data for the determination of the river flows. The method makes use of fact that as the flow in a river rises or falls, the areal extent covered by the river changes accordingly. Furthermore, barring anthropogenic changes, the area inundated by a flow of a particular magnitude is invariant in time. For a given stretch of a river, a sequence of images spanning the full range of flow conditions provides the basic template for determining river flows. The actual flow in the river can be calibrated using previously measured flow data corresponding the dates of old aerial or satellite imagery, or calculated from new imagery by using standard flow equations and the topography of the banks of the river, determined by field surveying or Lidar. Once the basic template has been established, determination of "the state-of-the-river" at any point in time can be obtained by comparing newly-acquired UAV images with those in the database. And because a given image encompasses many topographic features that are inundated to differing extents, the resolution of the flow determination is limited only by the completeness of the imagery in the basic template. Repeat flights at weekly

  17. Applications of electrical resistance tomography to subsurface environmental restoration

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A.L. [Lawrence Livermore National Lab., CA (United States); Daily, W.D.

    1994-11-15

    We are developing a new imaging technique, Electrical Resistance Tomography (ERT), to map subsurface liquids as flow occurs during natural or clean-up processes and to map geologic structure. Natural processes (such as surface water infiltrating the vadose zone) and man-induced processes (such as tank leaks and clean-up processes such as steam injection), can create changes in a soil`s electrical properties that are readily measured. We have conducted laboratory and a variety of field experiments to investigate the capabilities and limitations of ERT for imaging underground structures and processes. In the last four years we have used ERT to successfully monitor several field processes including: a subsurface steam injection process (for VOC removal), an air injection process (below the water table) for VOC removal, water infiltration through the vadose zone, radio-frequency heating, ohmic heating, and tank and pond leaks. The information derived from ERT can be used by remediation projects to: detect and locate leaks, determine the effectiveness of clean-up processes, select appropriate clean-up alternatives, and to verify the installation and performance of subsurface barriers.

  18. Longitudinal optical monitoring of blood flow in breast tumors during neoadjuvant chemotherapy

    Science.gov (United States)

    Cochran, J. M.; Chung, S. H.; Leproux, A.; Baker, W. B.; Busch, D. R.; DeMichele, A. M.; Tchou, J.; Tromberg, B. J.; Yodh, A. G.

    2017-06-01

    We measure tissue blood flow markers in breast tumors during neoadjuvant chemotherapy and investigate their correlation to pathologic complete response in a pilot longitudinal patient study (n  =  4). Tumor blood flow is quantified optically by diffuse correlation spectroscopy (DCS), and tissue optical properties, blood oxygen saturation, and total hemoglobin concentration are derived from concurrent diffuse optical spectroscopic imaging (DOSI). The study represents the first longitudinal DCS measurement of neoadjuvant chemotherapy in humans over the entire course of treatment; it therefore offers a first correlation between DCS flow indices and pathologic complete response. The use of absolute optical properties measured by DOSI facilitates significant improvement of DCS blood flow calculation, which typically assumes optical properties based on literature values. Additionally, the combination of the DCS blood flow index and the tissue oxygen saturation from DOSI permits investigation of tissue oxygen metabolism. Pilot results from four patients suggest that lower blood flow in the lesion-bearing breast is correlated with pathologic complete response. Both absolute lesion blood flow and lesion flow relative to the contralateral breast exhibit potential for characterization of pathological response. This initial demonstration of the combined optical approach for chemotherapy monitoring provides incentive for more comprehensive studies in the future and can help power those investigations.

  19. Developing an Integrated Monitoring and Evaluation Flow for Sustainable Investment Projects

    Directory of Open Access Journals (Sweden)

    Florin TACHE

    2011-12-01

    Full Text Available Under the circumstances of certain weaknesses in the monitoring and evaluation processes of sustainable investment projects, the paper aims to develop a general integrated flow, encompassing both a project monitoring system and also a project evaluation system for the investment projects involving economic objectives, as well as cross-cutting social and environmental targets. The whole approach is being presented as a flowchart, which highlights the intimate relationship between the monitoring and evaluation processes, and provides a formal framework for performing a logical monitoring and evaluation process, taking into account simultaneously the economic, social and environmental perspectives, within an investment project. Last, but not least, the article states both the estimated advantages and the disadvantages of such a managerial tool, opening new perspectives for developing further improved models and systems.

  20. Implementation of the Fissile Mass Flow Monitor Source Verification and Confirmation

    Energy Technology Data Exchange (ETDEWEB)

    Uckan, Taner [ORNL; March-Leuba, Jose A [ORNL; Powell, Danny H [ORNL; Nelson, Dennis [Sandia National Laboratories (SNL); Radev, Radoslav [Lawrence Livermore National Laboratory (LLNL)

    2007-12-01

    This report presents the verification procedure for neutron sources installed in U.S. Department of Energy equipment used to measure fissile material flow. The Fissile Mass Flow Monitor (FMFM) equipment determines the {sup 235}U fissile mass flow of UF{sub 6} gas streams by using {sup 252}Cf neutron sources for fission activation of the UF{sub 6} gas and by measuring the fission products in the flow. The {sup 252}Cf sources in each FMFM are typically replaced every 2 to 3 years due to their relatively short half-life ({approx} 2.65 years). During installation of the new FMFM sources, the source identity and neutronic characteristics provided by the manufacturer are verified with the following equipment: (1) a remote-control video television (RCTV) camera monitoring system is used to confirm the source identity, and (2) a neutron detection system (NDS) is used for source-strength confirmation. Use of the RCTV and NDS permits remote monitoring of the source replacement process and eliminates unnecessary radiation exposure. The RCTV, NDS, and the confirmation process are described in detail in this report.

  1. Low parameter model to monitor bottom hole pressure in vertical multiphase flow in oil production wells

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Ahmadi

    2016-09-01

    Full Text Available The importance of the flow patterns through petroleum production wells proved for upstream experts to provide robust production schemes based on the knowledge about flow behavior. To provide accurate flow pattern distribution through production wells, accurate prediction/representation of bottom hole pressure (BHP for determining pressure drop from bottom to surface play important and vital role. Nevertheless enormous efforts have been made to develop mechanistic approach, most of the mechanistic and conventional models or correlations unable to estimate or represent the BHP with high accuracy and low uncertainty. To defeat the mentioned hurdle and monitor BHP in vertical multiphase flow through petroleum production wells, inventive intelligent based solution like as least square support vector machine (LSSVM method was utilized. The evolved first-break approach is examined by applying precise real field data illustrated in open previous surveys. Thanks to the statistical criteria gained from the outcomes obtained from LSSVM approach, the proposed least support vector machine (LSSVM model has high integrity and performance. Moreover, very low relative deviation between the model estimations and the relevant actual BHP data is figured out to be less than 6%. The output gained from LSSVM model are closed the BHP while other mechanistic models fails to predict BHP through petroleum production wells. Provided solutions of this study explicated that implies of LSSVM in monitoring bottom-hole pressure can indicate more accurate monitoring of the referred target which can lead to robust design with high level of reliability for oil and gas production operation facilities.

  2. Flow dynamics in hyper-saline aquifers: hydro-geophysical monitoring and modeling

    Science.gov (United States)

    Haaken, Klaus; Piero Deidda, Gian; Cassiani, Giorgio; Deiana, Rita; Putti, Mario; Paniconi, Claudio; Scudeler, Carlotta; Kemna, Andreas

    2017-03-01

    Saline-freshwater interaction in porous media is a phenomenon of practical interest particularly for the management of water resources in arid and semi-arid environments, where precious freshwater resources are threatened by seawater intrusion and where storage of freshwater in saline aquifers can be a viable option. Saline-freshwater interactions are controlled by physico-chemical processes that need to be accurately modeled. This in turn requires monitoring of these systems, a non-trivial task for which spatially extensive, high-resolution non-invasive techniques can provide key information. In this paper we present the field monitoring and numerical modeling components of an approach aimed at understanding complex saline-freshwater systems. The approach is applied to a freshwater injection experiment carried out in a hyper-saline aquifer near Cagliari (Sardinia, Italy). The experiment was monitored using time-lapse cross-hole electrical resistivity tomography (ERT). To investigate the flow dynamics, coupled numerical flow and transport modeling of the experiment was carried out using an advanced three-dimensional (3-D) density-driven flow-transport simulator. The simulation results were used to produce synthetic ERT inversion results to be compared against real field ERT results. This exercise demonstrates that the evolution of the freshwater bulb is strongly influenced by the system's (even mild) hydraulic heterogeneities. The example also highlights how the joint use of ERT imaging and gravity-dependent flow and transport modeling give fundamental information for this type of study.

  3. Subsurface Airflow Induced by Natural Forcings

    Institute of Scientific and Technical Information of China (English)

    Jiu J. Jiao; LI Hai-long

    2004-01-01

    Subsurface air flow can be induced by natural processes, such as atmospheric or barometric pressure changes, water table fluctuations, topographic effects, and rainfall infiltration. Barometric pressure fluctuations are the most common cause of subsurface air flow, which can be significant under favourable geological conditions. This process has been studied most extensively because of its application to passive soil vapor extraction. Soil air flow induced by water table fluctuations can be significant, particularly where the fluctuations are of high frequency, for example, in tidal-influenced coastal areas. Topographic effects can lead to strong subsoil air flow in areas with great elevation differences. Rainfall infiltration usually produces only weak airflow. Air flow induced by these natural processes has important environmental and engineering implications. Among the different processes, air flow induced by tidal fluctuations has been studied the least, although it has exciting applications to coastal engineering projects and environmental remediation.

  4. Doppler standard deviation imaging for clinical monitoring of in vivo human skin blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yonghua; Chen, Zhongping; Saxer, Christopher; Shen, Qimin; Xiang, Shaohua; Boer, Johannes F. de; Nelson, J. Stuart

    2000-09-15

    We used a novel phase-resolved optical Doppler tomographic (ODT) technique with very high flow-velocity sensitivity (10 {mu}m/s) and high spatial resolution (10 {mu}m) to image blood flow in port-wine stain (PWS) birthmarks in human skin. In addition to the regular ODT velocity and structural images, we use the variance of blood flow velocity to map the PWS vessels. Our device combines ODT and therapeutic systems such that PWS blood flow can be monitored in situ before and after laser treatment. To the authors' knowledge this is the first clinical application of ODT to provide a fast semiquantitative evaluation of the efficacy of PWS laser therapy in situ and in real time. (c) 2000 Optical Society of America.

  5. High frequency seismic monitoring of debris flows at Chalk Cliffs (CO), USA

    Science.gov (United States)

    Coviello, Velio; Kean, Jason; Smith, Joel; Coe, Jeffrey; Arattano, Massimo; McCoy, Scott

    2015-04-01

    A growing number of studies adopt passive seismic monitoring techniques to investigate slope instabilities and landslide processes. These techniques are attractive and convenient because large areas can be monitored from a safe distance. This is particularly true when the phenomena under investigation are rapid and infrequent mass movements like debris flows. Different types of devices are used to monitor debris flow processes, but among them ground vibration detectors (GVDs) present several, specific advantages that encourage their use. These advantages include: (i) the possibility to be installed outside the channel bed, (ii) the high adaptability to different and harsh field conditions, and (iii) the capability to detect the debris flow front arrival tens of seconds earlier than contact and stage sensors. Ground vibration data can provide relevant information on the dynamics of debris flows such as timing and velocity of the main surges. However, the processing of the raw seismic signal is usually needed, both to obtain a more effective representation of waveforms and to decrease the amount of data that need to be recorded and analyzed. With this objective, the methods of Amplitude and Impulses are commonly adopted to transform the raw signal to a 1-Hz signal that allows for a more useful representation of the phenomenon. In that way, peaks and other features become more visible and comparable with data obtained from other monitoring devices. In this work, we present the first debris flows seismic recordings gathered in the Chalk Cliffs instrumented basin, central Colorado, USA. In May 2014, two 4.5-Hz, three-axial geophones were installed in the upper part of the catchment. Seismic data are sampled at 333 Hz and then recorded by a standalone recording unit. One geophone is directly installed on bedrock, the other one mounted on a 1-m boulder partially buried in colluvium. This latter sensor integrates a heavily instrumented cross-section consisting of a 225 cm2

  6. Multiplexed fibre optic sensors for monitoring resin infusion, flow, and cure in composite material processing

    Science.gov (United States)

    Chehura, Edmon; Jarzebinska, Renata; Da Costa, Elisabete F. R.; Skordos, Alexandros A.; James, Stephen W.; Partridge, Ivana K.; Tatam, Ralph P.

    2013-04-01

    The infusion, flow and cure of RTM6 resin in a carbon fibre reinforced composite preform have been monitored using a variety of multiplexed fibre optic sensors. Optical fibre Fresnel sensors and tilted fibre Bragg grating (TFBG) sensors were configured to monitor resin infusion/flow in-plane of the component. The results obtained from the different sensors were in good agreement with visual observations. The degree of cure was monitored by Fresnel sensors via a measurement of the refractive index of the resin which was converted to degree of cure using a calibration determined from Differential Scanning Calorimetry. Fibre Bragg grating sensors fabricated in highly linearly birefringent fibre were used to monitor the development of transverse strain during the cure process, revealing through-thickness material shrinkage of about 712 μɛ and residual strain of 223 μɛ. An alternative approach to infusion monitoring, based on an array of multiplexed tapered optical fibre sensors interrogated using optical frequency domain reflectometry, was also investigated in a separate carbon fibre preform that was infused with RTM6 resin.

  7. Observing hydrological processes: recent advancements in surface flow monitoring through image analysis

    Science.gov (United States)

    Tauro, Flavia; Grimaldi, Salvatore

    2017-04-01

    Recently, several efforts have been devoted to the design and development of innovative, and often unintended, approaches for the acquisition of hydrological data. Among such pioneering techniques, this presentation reports recent advancements towards the establishment of a novel noninvasive and potentially continuous methodology based on the acquisition and analysis of images for spatially distributed observations of the kinematics of surface waters. The approach aims at enabling rapid, affordable, and accurate surface flow monitoring of natural streams. Flow monitoring is an integral part of hydrological sciences and is essential for disaster risk reduction and the comprehension of natural phenomena. However, water processes are inherently complex to observe: they are characterized by multiscale and highly heterogeneous phenomena which have traditionally demanded sophisticated and costly measurement techniques. Challenges in the implementation of such techniques have also resulted in lack of hydrological data during extreme events, in difficult-to-access environments, and at high temporal resolution. By combining low-cost yet high-resolution images and several velocimetry algorithms, noninvasive flow monitoring has been successfully conducted at highly heterogeneous scales, spanning from rills to highly turbulent streams, and medium-scale rivers, with minimal supervision by external users. Noninvasive image data acquisition has also afforded observations in high flow conditions. Latest novelties towards continuous flow monitoring at the catchment scale have entailed the development of a remote gauge-cam station on the Tiber River and integration of flow monitoring through image analysis with unmanned aerial systems (UASs) technology. The gauge-cam station and the UAS platform both afford noninvasive image acquisition and calibration through an innovative laser-based setup. Compared to traditional point-based instrumentation, images allow for generating surface

  8. Blend Down Monitoring System Fissile Mass Flow Monitor and its Implementation at the Siberian Chemical Enterprise, Seversk, Russia

    Energy Technology Data Exchange (ETDEWEB)

    Uckan, T

    2005-07-28

    In this paper the implementation plans and preparations for installation of the Fissile Mass Flow Monitor (FMFM) equipment at the Siberian Chemical Enterprise (SChE), Seversk, Russia, are presented. The FMFM, developed by Oak Ridge National Laboratory, is part of the Blend Down Monitoring System (BDMS) for the U.S. Department of Energy Highly Enriched Uranium (HEU) Transparency Implementation Program. The BDMS provides confidence to the United States that the Russian nuclear facilities supplying the lower assay ({approx}4%) product low enriched uranium (PLEU) to the United States from down-blended weapon-grade HEU are meeting the nonproliferation goals of the government-to-government HEU purchase agreement signed between the Russian Federation and the United States in 1993. The first BDMS has been operational at Ural Electrochemical Integrated Plant, Novouralsk, since February 1999. The second BDMS has been operational at Electro Chemical Plant, Zelenogorsk, since March 2003. These systems are successfully providing HEU transparency data to the United States. The third BDMS was successfully installed on the HEU down-blending tee in the SChE Enrichment Plant in October 2004. The FMFM makes use of a set of thermalized {sup 252}Cf spontaneous neutron sources for modulated fission activation of the UF{sub 6} gas stream for measuring the {sup 235}U fissile mass flow rate. To do this, the FMFM measures the transport time of the fission fragments created from the fission activation process under the modulated source to the downstream detectors by detecting the delayed gamma rays from the fission fragments retained in the flow. The FMFM provides unattended nonintrusive measurements of the {sup 235}U mass flow of the UF{sub 6} gas in the blending tee legs of HEU, the LEU blend stock, and the resulting P-LEU. The FMFM also confirms that highly enriched UF{sub 6} gas identified in the HEU leg flows through the blending tee into the P-LEU leg. This report contains details of

  9. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  10. Dielectrophoresis microsystem with integrated flow cytometers for on-line monitoring of sorting efficiency

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Hansen, Ole; Petersen, Peter Kalsen

    2006-01-01

    Dielectrophoresis (DEP) and flow cytometry are powerful technologies and widely applied in microfluidic systems for handling and measuring cells and particles. Here, we present a novel microchip with a DEP selective filter integrated with two microchip flow cytometers (FCs) for on-line monitoring...... of cell sorting processes. On the microchip, the DEP filter is integrated in a microfluidic channel network to sort yeast cells by positive DER The two FCs detection windows are set upstream and downstream of the DEP filter. When a cell passes through the detection windows, the light scattered by the cell...

  11. New turbidity current model based on high-resolution monitoring of the longest flow ever measured

    Science.gov (United States)

    Azpiroz, Maria; Cartigny, Matthieu; Talling, Peter; Parsons, Daniel; Simmons, Steve; Clare, Michael; Sumner, Esther; Pope, Ed

    2016-04-01

    Turbidity currents transport large amounts of sediment from shallow waters towards deep ocean basins. Little is known about these flows, despite their potential hazard for damaging expensive and strategically important seafloor infrastructure. So far turbidity currents have been profiled in only 6 deep ocean locations worldwide. Our current knowledge of these flows is therefore mainly based on scaled-down experimental and computationally-limited numerical modelling. Here we present results from the monitoring of a one-week long turbidity current in the Congo Canyon that had a discharge close to that of the Mississippi River. Measurements taken every 5 seconds give the most detailed image yet of a turbidity current deep-water over an unprecedented duration. Our analysis reveals a different flow structure than that presented in previous models. Classical models display a thick front of the flow followed by a thinner and faster flow, which gives way to a short and quasi-steady body. Instead, we observe a thin frontal cell that outruns a thicker (~80 m), long and slower quasi-steady flow. In contrast to the previous model, where the thinner faster flow feeds sediment into the head, the Congo Canyon turbidity current shows a frontal cell that feeds sediment into, and at the same time outruns, the succeeding quasi-steady flow. As a result of the faster moving frontal cell, the flow should continuously stretch and grow in length while propagating down the system. Within the quasi-steady body, the flow switches between what appears to be two stable flow modes. One mode exhibits a fast and thin velocity profile whose maximum is a low distance from the seabed and resembles Froude-supercritical flow conditions, while the other mode is similar to Froude-subcritical flow conditions as the flow is thicker and slower. These first observations provide new insights into the behaviour of deep water long duration flows that differ from traditional models and provide an exciting

  12. Monitoring the Erosion of Hydrolytically-Degradable Nanogels via Multiangle Light Scattering Coupled to Asymmetrical Flow Field-Flow Fractionation

    Science.gov (United States)

    Smith, Michael H.; South, Antoinette B.; Gaulding, Jeffrey C.; Lyon, L. Andrew

    2009-01-01

    We describe the synthesis and characterization of degradable nanogels that display bulk erosion under physiologic conditions (pH = 7.4, 37 °C). Erodible poly(N-isopropylmethacrylamide) nanogels were synthesized by copolymerization with N,O-(dimethacryloyl)hydroxylamine, a cross-linker previously used in the preparation of non-toxic and biodegradable bulk hydrogels. To monitor particle degradation, we employed multiangle light scattering and differential refractometry detection following asymmetrical flow field-flow fractionation. This approach allowed the detection of changes in nanogel molar mass and topology as a function of both temperature and pH. Particle erosion was evident from both an increase in nanogel swelling and a decrease in scattering intensity as a function of time. Following these analyses, the samples were recovered for subsequent characterization by direct particle tracking, which yields hydrodynamic size measurements and enables number density determination. Additionally, we confirmed the conservation of nanogel stimuli-responsivity through turbidity measurements. Thus, we have demonstrated the synthesis of degradable nanogels that erode under conditions and on timescales that are relevant for many drug delivery applications. The combined separation and light scattering detection method is demonstrated to be a versatile means to monitor erosion and should also find applicability in the characterization of other degradable particle constructs. PMID:20000662

  13. SUBSURFACE REPOSITORY INTEGRATED CONTROL SYSTEM DESIGN

    Energy Technology Data Exchange (ETDEWEB)

    D.C. Randle

    2000-01-07

    The primary purpose of this document is to develop a preliminary high-level functional and physical control system architecture for the potential repository at Yucca Mountain. This document outlines an overall control system concept that encompasses and integrates the many diverse process and communication systems being developed for the subsurface repository design. This document presents integrated design concepts for monitoring and controlling the diverse set of subsurface operations. The Subsurface Repository Integrated Control System design will be composed of a series of diverse process systems and communication networks. The subsurface repository design contains many systems related to instrumentation and control (I&C) for both repository development and waste emplacement operations. These systems include waste emplacement, waste retrieval, ventilation, radiological and air monitoring, rail transportation, construction development, utility systems (electrical, lighting, water, compressed air, etc.), fire protection, backfill emplacement, and performance confirmation. Each of these systems involves some level of I&C and will typically be integrated over a data communications network throughout the subsurface facility. The subsurface I&C systems will also interface with multiple surface-based systems such as site operations, rail transportation, security and safeguards, and electrical/piped utilities. In addition to the I&C systems, the subsurface repository design also contains systems related to voice and video communications. The components for each of these systems will be distributed and linked over voice and video communication networks throughout the subsurface facility. The scope and primary objectives of this design analysis are to: (1) Identify preliminary system-level functions and interfaces (Section 6.2). (2) Examine the overall system complexity and determine how and on what levels the engineered process systems will be monitored, controlled, and

  14. Monitoring and Evaluation of Environmental Flow Prescriptions for Five Demonstration Sites of the Sustainable Rivers Project

    Science.gov (United States)

    Konrad, Christopher P.

    2010-01-01

    The Nature Conservancy has been working with U.S. Army Corps of Engineers (Corps) through the Sustainable Rivers Project (SRP) to modify operations of dams to achieve ecological objectives in addition to meeting the authorized purposes of the dams. Modifications to dam operations are specified in terms of environmental flow prescriptions that quantify the magnitude, duration, frequency, and seasonal timing of releases to achieve specific ecological outcomes. Outcomes of environmental flow prescriptions implemented from 2002 to 2008 have been monitored and evaluated at demonstration sites in five rivers: Green River, Kentucky; Savannah River, Georgia/South Carolina; Bill Williams River, Arizona; Big Cypress Creek, Texas; and Middle Fork Willamette River, Oregon. Monitoring and evaluation have been accomplished through collaborative partnerships of federal and state agencies, universities, and nongovernmental organizations.

  15. Analysis of novel geometry-independent method for dialysis access pressure-flow monitoring

    Directory of Open Access Journals (Sweden)

    Panduranga Harsha

    2008-11-01

    Full Text Available Abstract Background End-stage renal disease (ESRD confers a large health-care burden for the United States, and the morbidity associated with vascular access failure has stimulated research into detection of vascular access stenosis and low flow prior to thrombosis. We present data investigating the possibility of using differential pressure (ΔP monitoring to estimate access flow (Q for dialysis access monitoring, with the goal of utilizing micro-electro-mechanical systems (MEMS pressure sensors integrated within the shaft of dialysis needles. Methods A model of the arteriovenous graft fluid circuit was used to study the relationship between Q and the ΔP between two dialysis needles placed 2.5–20.0 cm apart. Tubing was varied to simulate grafts with inner diameters of 4.76–7.95 mm. Data were compared with values from two steady-flow models. These results, and those from computational fluid dynamics (CFD modeling of ΔP as a function of needle position, were used to devise and test a method of estimating Q using ΔP and variable dialysis pump speeds (variable flow that diminishes dependence on geometric factors and fluid characteristics. Results In the fluid circuit model, ΔP increased with increasing volume flow rate and with increasing needle-separation distance. A nonlinear model closely predicts this ΔP-Q relationship (R2 > 0.98 for all graft diameters and needle-separation distances tested. CFD modeling suggested turbulent needle effects are greatest within 1 cm of the needle tip. Utilizing linear, quadratic and combined variable flow algorithms, dialysis access flow was estimated using geometry-independent models and an experimental dialysis system with the pressure sensors separated from the dialysis needle tip by distances ranging from 1 to 5 cm. Real-time ΔP waveform data were also observed during the mock dialysis treatment, which may be useful in detecting low or reversed flow within the access. Conclusion With further

  16. Microstrip antennas in subsurface sensing

    Science.gov (United States)

    Volgyi, Ferenc

    2000-07-01

    This paper reviews the various applications of microstrip antennas with special emphasis on subsurface sensing, microwave moisture measurement and nondestructive testing of dielectric materials. With reference to the literature, we first describe the commonly used GPR-antennas, the printed Vivaldi-antennas, and microstrip antennas used in moisture content measurement. Furthermore, attention is given to the problems of new antenna technologies, showing examples for active integrated antennas, a photonic band gap patch antenna and a silicon micromachined patch antenna. The reminder of the paper summarizes relevant R&D activities in microstrip antennas at BUTE/DMT, focusing on near-field experiments, monitoring of particleboards and WLAN- applications of patch radiators.

  17. Immune Monitoring in Cancer Vaccine Clinical Trials: Critical Issues of Functional Flow Cytometry-Based Assays

    OpenAIRE

    Iole Macchia; Francesca Urbani; Enrico Proietti

    2013-01-01

    The development of immune monitoring assays is essential to determine the immune responses against tumor-specific antigens (TSAs) and tumor-associated antigens (TAAs) and their possible correlation with clinical outcome in cancer patients receiving immunotherapies. Despite the wide range of techniques used, to date these assays have not shown consistent results among clinical trials and failed to define surrogate markers of clinical efficacy to antitumor vaccines. Multiparameter flow cytometr...

  18. A lactose flow injection analysis biosensor system for monitoring and process control

    OpenAIRE

    2004-01-01

    In this work an enzymatic lactose biosensor composed of the immobilized enzymes E- galactosidase and glucose oxidase was developed. Oxygen consumption during the reaction catalyzed by these enzymes was detected. The biosensor was integrated into an FIA (flow injection analysis) system that allows measurement of lactose on-line in less than three minutes. This biosensor was used to monitor lactose concentration during the production of E-galactosidase by the yeast Kluyveromyces marxianus from ...

  19. Seismic Survey Report for Central Nevada Test Area, Subsurface, Correction Action Unit 443, Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    None

    2008-12-19

    The seismic survey was successful in imaging the water table and underlying structures at the site. The configuration of the water table reflector confirms the general southeast horizontal flow direction in the alluvial aquifer. Offsets in the water table reflector, both at known faults that reach the surface and at subsurface faults not previously recognized, indicate that both extension and blast-related faults are barriers to lateral groundwater flow. The results from this study have been used to optimally locate two new wells designed to monitor head levels and possible contaminant migration in the alluvial aquifer at CTNA.

  20. Surface and Subsurface Geochemical Monitoring of an EOR-CO2 Field: Buracica, Brazil Monitoring géochimique en surface et sub-surface d’un gisement en production par récupération assistée et injection de CO2 : le champ de Buracica, Brésil

    Directory of Open Access Journals (Sweden)

    Magnier C.

    2012-04-01

    Full Text Available This paper presents a surface and subsurface geochemical survey of the Buracica EOR-CO2 field onshore Brazil. We adopted a methodology coupling the stable isotopes of carbon with noble gases to investigate the adequacy of geochemical monitoring to track deep fluid leakage at the surface. Three campaigns of CO2 flux and concentration in soils were performed to understand the CO2 variability across the field. The distribution of the CO2 soil contents between 0.8 and 14% is in great part controlled by the properties of the soil, with a first-order topographic dependency. These results, together with a δ13CCO2 between –15 and –23‰, suggest that the bulk of the soil CO2 flux is biological. The gas injected and produced at numerous wells across the field showed a great spatial and somewhat temporal heterogeneity with respect to molecular, δ13CCO2 and noble gas compositions. This heterogeneity is a consequence of the EOR-induced sweeping of the petroleum fluids by the injected CO2, producing a heterogeneous mixing controlled by the production scheme and the distribution in reservoir permeability. In light of the δ13CCO2 found in the reservoir, the stable isotopic composition of carbon was insufficient to track CO2 leaks at the surface. We demonstrate how noble gases may be powerful leak discriminators, even for CO2 abundances in soils in the bottom range of the biological baseline (~1%. The results presented in this study show the potential of geochemical monitoring techniques, involving stable isotopes and noble gases at the reservoir and soil levels, for tracing CO2 in CCS projects. Le monitoring géochimique du gisement de Buracica, qui produit des hydrocarbures par récupération assistée et injection de dioxyde de carbone, est présenté dans cet article. Une méthodologie permettant de coupler l’utilisation des isotopes stables du carbone et des isotopes des gaz rares pour étudier la faisabilité de traçage d’une fuite de CO2 du r

  1. Water and Solute Transport in the Shallow Subsurface of a Natural Levee

    Science.gov (United States)

    Newman, A.; Keim, R.

    2008-12-01

    In riverine wetlands, river channels are separated from backswamps by natural levees that form adjacent to the channel by sediment deposition during floods. The conventional conceptual framework is that backswamp water is impounded and disconnected from surface flow; however, layered sediments, shrink-swell clays, roots and decayed organic matter, and animal burrows likely form preferential pathways for subsurface flow and may substantially affect water and solute exchange between wetlands and river channels. To test the hypothesis that preferential flow is an important pathway of subsurface water movement through natural levees, we measured hydraulic gradients and solute tracers in a 5 x 5 m grid of 19 shallow (2m) monitoring wells within a large representative elementary volume (300 m3) of natural levee in the Atchafalaya Basin, Louisiana. In addition to measuring transient responses to precipitation, we constructed a small reservoir on the backswamp side of the levee to simulate a seasonal hydraulic gradient from the swamp to the adjacent river channel. Results indicate rapid response of water levels in all monitoring wells to the imposed hydraulic gradient as well as rain events, which included two tropical cyclones. In contrast, tracer response was highly variable, both spatially and across events, indicating a complex relationship between subsurface flow processes and water chemistry. Groundwater chemistry indicated spatially variable flowpaths. In some wells, hydraulic response coincided with a chemical shift toward low-conductivity surface water; however, other wells showed similar hydraulic responses but no change in tracer concentrations or even a shift toward higher-conductivity water that was presumably stored in the soil matrix. This spatial variation in tracer response indicates multiple mechanisms of hydraulic response, each of which has important implications for biogeochemical interactions between backswamps and channels in the shallow subsurface

  2. Development of fuel flow monitoring system in prototype fast breeder reactor 'MONJU'

    Energy Technology Data Exchange (ETDEWEB)

    Tomura, Katsuji; Deshimaru; Takehide; Okuda, Yoshihisa; Ohba, Toshio (Power Reactor and Nuclear Fuel Development Corp., Tsuruga, Fukui (Japan). Monju Construction Office); Ishikawa, Kouichi

    1994-06-01

    A new safeguards approach of Prototype Fast Breeder Reactor 'MONJU' has been studied by Japanese Government, IAEA and PNC to meet 1991-1995 safeguards criteria. As the result, a fuel flow monitoring system has been introduced in 'MONJU'. Development of the system has been conducted by PNC and IAEA with technical support of Los Alamos National Laboratory. Safeguards measures in unattended mode with the system can detect fuel loading and unloading into and from the reactor core and distinguish what kind of the fuel. The system are consisted of three monitors using neutron and gamma-ray measurements and video surveillance system. Installation of these monitors was finished by PNC and acceptance test by Japanese Government and IAEA was carried out March, 1992. (author).

  3. Monitoring And Analyzing Distributed Cluster Performance And Statistics Of Atlas Job Flow

    CERN Document Server

    Ramprakash, S

    2005-01-01

    The ATLAS experiment is a High Energy Physics experiment that utilizes the services of Grid3 now migrating to the Open Science Grid (OSG). This thesis provides monitoring and analysis of performance and statistical data from individual distributed clusters that combine to form the ATLAS Grid and will ultimately be used to make scheduling decisions on this Grid. The system developed in this thesis uses a layered architecture such that predicted future developments or changes brought to the existing Grid infrastructure can easily utilize this work with minimum or no changes. The starting point of the system is based on the existing scheduling that is being done manually for ATLAS job flow. We have provided additional functionality based on the requirements of the High Energy Physics ATLAS team of physicists at UTA. The system developed in this thesis has successfully monitored and analyzed distributed cluster performance at three sites and is waiting for access to monitor data from three more sites. (Abstract s...

  4. Brief Communication: A low-cost Arduino®-based wire extensometer for earth flow monitoring

    Directory of Open Access Journals (Sweden)

    L. Guerriero

    2017-06-01

    Full Text Available Continuous monitoring of earth flow displacement is essential for the understanding of the dynamic of the process, its ongoing evolution and designing mitigation measures. Despite its importance, it is not always applied due to its expense and the need for integration with additional sensors to monitor factors controlling movement. To overcome these problems, we developed and tested a low-cost Arduino-based wire-rail extensometer integrating a data logger, a power system and multiple digital and analog inputs. The system is equipped with a high-precision position transducer that in the test configuration offers a measuring range of 1023 mm and an associated accuracy of ±1 mm, and integrates an operating temperature sensor that should allow potential thermal drift that typically affects this kind of systems to be identified and corrected. A field test, conducted at the Pietrafitta earth flow where additional monitoring systems had been installed, indicates a high reliability of the measurement and a high monitoring stability without visible thermal drift.

  5. Brief Communication: A low-cost Arduino®-based wire extensometer for earth flow monitoring

    Science.gov (United States)

    Guerriero, Luigi; Guerriero, Giovanni; Grelle, Gerardo; Guadagno, Francesco M.; Revellino, Paola

    2017-06-01

    Continuous monitoring of earth flow displacement is essential for the understanding of the dynamic of the process, its ongoing evolution and designing mitigation measures. Despite its importance, it is not always applied due to its expense and the need for integration with additional sensors to monitor factors controlling movement. To overcome these problems, we developed and tested a low-cost Arduino-based wire-rail extensometer integrating a data logger, a power system and multiple digital and analog inputs. The system is equipped with a high-precision position transducer that in the test configuration offers a measuring range of 1023 mm and an associated accuracy of ±1 mm, and integrates an operating temperature sensor that should allow potential thermal drift that typically affects this kind of systems to be identified and corrected. A field test, conducted at the Pietrafitta earth flow where additional monitoring systems had been installed, indicates a high reliability of the measurement and a high monitoring stability without visible thermal drift.

  6. Monitoring bacterial biofilms with a microfluidic flow chip designed for imaging with white-light interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Brann, Michelle; Suter, Jonathan D.; Addleman, R. Shane; Larimer, Curtis

    2017-07-01

    There is a need for imaging and sensing instrumentation that can monitor transitions in biofilm structure in order to better understand biofilm development and emergent properties such as anti-microbial resistance. Herein, we expanded on our previously reported technique for measuring and monitoring the thickness and topology of live biofilms using white-light interferometry (WLI). A flow cell designed for WLI enabled the use of this non-disruptive imaging method for the capture of high resolution three-dimensional profile images of biofilm growth over time. The fine axial resolution (3 nm) and wide field of view (>1 mm by 1 mm) enabled detection of biofilm formation as early as three hours after inoculation of the flow cell with a live bacterial culture (Pseudomonas fluorescens). WLI imaging facilitated monitoring the early stages of biofilm development and subtle variations in the structure of mature biofilms. Minimally-invasive imaging enabled monitoring of biofilm structure with surface metrology metrics (e.g., surface roughness). The system was used to observe a transition in biofilm structure that occurred in response to expsoure to a common antiseptic. In the future, WLI and the biofilm imaging cell described herein may be used to test the effectiveness of biofilm-specific therapies to combat common diseases associated with biofilm formation such as cystic fibrosis and periodontitis.

  7. SUBSURFACE REPOSITORY INTEGRATED CONTROL SYSTEM DESIGN

    Energy Technology Data Exchange (ETDEWEB)

    C.J. Fernado

    1998-09-17

    The purpose of this document is to develop preliminary high-level functional and physical control system architectures for the proposed subsurface repository at Yucca Mountain. This document outlines overall control system concepts that encompass and integrate the many diverse systems being considered for use within the subsurface repository. This document presents integrated design concepts for monitoring and controlling the diverse set of subsurface operations. The subsurface repository design will be composed of a series of diverse systems that will be integrated to accomplish a set of overall functions and objectives. The subsurface repository contains several Instrumentation and Control (I&C) related systems including: waste emplacement systems, ventilation systems, communication systems, radiation monitoring systems, rail transportation systems, ground control monitoring systems, utility monitoring systems (electrical, lighting, water, compressed air, etc.), fire detection and protection systems, retrieval systems, and performance confirmation systems. Each of these systems involve some level of I&C and will typically be integrated over a data communication network. The subsurface I&C systems will also integrate with multiple surface-based site-wide systems such as emergency response, health physics, security and safeguards, communications, utilities and others. The scope and primary objectives of this analysis are to: (1) Identify preliminary system level functions and interface needs (Presented in the functional diagrams in Section 7.2). (2) Examine the overall system complexity and determine how and on what levels these control systems will be controlled and integrated (Presented in Section 7.2). (3) Develop a preliminary subsurface facility-wide design for an overall control system architecture, and depict this design by a series of control system functional block diagrams (Presented in Section 7.2). (4) Develop a series of physical architectures that

  8. Blood flow changes after unilateral carotid artery ligation monitored by optical coherence tomography

    Science.gov (United States)

    Ma, Yushu; Liang, Chengbo; Suo, Yanyan; Zhao, Yuqian; Wang, Yi; Xu, Tao; Wang, Ruikang; Ma, Zhenhe

    2016-03-01

    Unilateral carotid artery ligation which could induce adaptive improvement is a classic model that has been widely used to study pathology of ischemic disease. In those studies, blood flow is an important parameter to characterize the ischemia. Optical coherence tomography (OCT) is a powerful imaging modality which can provide depth resolved images in biological tissue with high spatial and temporal resolution. SPF rats was anesthetized with isoflurane and divided into two groups. In first group, bilateral carotid artery was surgically exposed, and then left carotid artery was ligated. Blood flow changes of the contralateral carotid artery was monitored using high speed spectral domain optical coherence tomography, including the absolute flow velocity and the flow volume. In the other group, skull window was opened at the ipsilateral cerebral cortex of ligation and blood supply of small artery was measured before and after the ligation. The measured results demonstrate the blood supply compensation process after unilateral carotid artery ligation. With the superiority of high resolution, OCT is an effective technology in monitoring results of carotid artery after ligation.

  9. Risk Exposure and Net Flow in Investment Funds: Do Shareholders Monitor Asset Allocation?

    Directory of Open Access Journals (Sweden)

    Rafael Felipe Schiozer

    2014-03-01

    Full Text Available This study investigates the impact of asset allocation on the net flow of fixed income funds in the Brazilian market, by exploiting the exogenous variation in the risk perception of bank liabilities (CDs caused by the financial turmoil that followed Lehman Brothers’ demise in September 2008. The central hypothesis is that the exposure to assets negatively affected by the crisis impacts negatively the fund’s net flow. We find that, for mutual funds, the larger proportion of assets negatively affected by the crisis the larger the net outflow of resources, indicating that shareholders monitor asset allocation and exert disciplining power on fund managers by withdrawing their resources. In exclusive (fundos exclusivos, i.e., funds with a single shareholder, for which the shareholder is presumed to exert more influence on asset reallocation, we find no significant relationship between the exposure to assets negatively affected by the crisis and net flows.

  10. A System for Simple Real-Time Anastomotic Failure Detection and Wireless Blood Flow Monitoring in the Lower Limbs

    Science.gov (United States)

    Rothfuss, Michael A.; Franconi, Nicholas G.; Unadkat, Jignesh V.; Gimbel, Michael L.; STAR, Alexander; Mickle, Marlin H.

    2016-01-01

    Current totally implantable wireless blood flow monitors are large and cannot operate alongside nearby monitors. To alleviate the problems with the current monitors, we developed a system to monitor blood flow wirelessly, with a simple and easily interpretable real-time output. To the best of our knowledge, the implanted electronics are the smallest in reported literature, which reduces bio-burden. Calibration was performed across realistic physiological flow ranges using a syringe pump. The device’s sensors connected directly to the bilateral femoral veins of swine. For each 1 min, blood flow was monitored, then, an occlusion was introduced, and then, the occlusion was removed to resume flow. Each vein of four pigs was monitored four times, totaling 32 data collections. The implant measured 1.70 cm3 without battery/encapsulation. Across its calibrated range, including equipment tolerances, the relative error is less than ±5% above 8 mL/min and between −0.8% and +1.2% at its largest calibrated flow rate, which to the best of our knowledge is the lowest reported in the literature across the measured calibration range. The average standard deviation of the flow waveform amplitude was three times greater than that of no-flow. Establishing the relative amplitude for the flow and no-flow waveforms was found necessary, particularly for noise modulated Doppler signals. Its size and accuracy, compared with other microcontroller-equipped totally implantable monitors, make it a good candidate for future tether-free free flap monitoring studies. PMID:27730016

  11. Monitoring of Underground Coal Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wagoner, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ramirez, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-08-31

    For efficient and responsible UCG operations, a UCG process must be monitored in the following three categories: 1) process parameters such as injection and product gas flow rates, temperature, pressure and syngas content and heating value; 2) geomechanical parameters, e.g., cavity and coal seam pressures, cavity development, subsidence and ground deformation; and 3) environmental parameters, e.g., groundwater chemistry and air quality. This report focuses on UCG monitoring with geophysical techniques that can contribute to monitoring of subsurface temperature, cavity development, burn front, subsidence and deformation.

  12. Debris flow monitoring experience in the Cancia basin (Dolomites, Northeast Italian Alps).

    Science.gov (United States)

    Stancanelli, Laura; Bernard, Martino; Gregoretti, Carlo; Berti, Matteo; Simoni, Alessandro; Lanzoni, Stefano

    2016-04-01

    The monitoring campaign presented here aims to understand the dynamics of sediment transport processes in small head-water catchments of the Italian Alps and to evaluate the rainfall thresholds for debris flow triggering. The monitored basin of Cancia is located on the Eastern Italian Dolomites, in the Belluno Province. In particular, it is situated on the left side on the Boite river valley, next to the Borca di Cadore village, and is delimited by the western slope of the Mt. Antelao. The drainage area is 1.8 km2 while the elevation ranges from 2451 m a.s.l. to 880 m a.s.l., with a slope varying from 30-40° in the upper part to 10-15° in the lower part (fan area). The basin is characterized by a lithology very common in the Italian Alps, which consist of high permeability, poorly sorted rock debris, containing boulders up to 3-4 m in diameter, and include heterogeneous scree, alluvium and old debris flow deposits. The spatial distribution of sediment is characterized by: an upper part where prevails the presence of rocks, a medium part characterized by poorly sorted rock debris and fine sediment material, and a downstream part plenty of sediment material The Cancia basin is prone to stony debris