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Sample records for modeling water table

  1. Model for a dune field with exposed water table

    CERN Document Server

    Luna, Marco Cesar M de M; Herrmann, Hans J

    2011-01-01

    Aeolian transport in coastal areas can be significantly affected by the presence of an exposed water table. In some dune fields, such as in Len\\c{c}\\'ois Maranhenses, northeastern Brazil, the water table oscillates in response to seasonal changes of rainfall and rates of evapotranspiration, rising above the ground during the wet season and sinking below in the dry period. A quantitative understanding of dune mobility in an environment with varying groundwater level is essential for coastal management as well as for the study of long-term evolution of many dune fields. Here we apply a model for aeolian dunes to study the genesis of coastal dune fields in presence of an oscillating water table. We find that the morphology of the field depends on the time cycle, $T_{\\mathrm{w}}$, of the water table and the maximum height, $H_{\\mathrm{w}}$, of its oscillation. Our calculations show that long chains of barchanoids alternating with interdune ponds such as found at Len\\c{c}\\'ois Maranhenses arise when $T_{\\mathrm{w}...

  2. Modeling water table fluctuations by means of a stochastic differential equation

    Science.gov (United States)

    Bierkens, Marc F. P.

    1998-10-01

    The combined system of soil-water and shallow groundwater is modeled with simple mass balance equations assuming equilibrium soil moisture conditions. This results in an ordinary but nonlinear differential equation of water table depth at a single location. If errors in model inputs, errors due to model assumptions and parameter uncertainty are lumped and modeled as a wide band noise process, a stochastic differential equation (SDE) results. A solution for the stationary probability density function is given through use of the Fokker-Planck equation. For the nonstationary case, where the model inputs are given as daily time series, sample functions of water table depth, soil saturation, and drainage discharge can be simulated by numerically solving the SDE. These sample functions can be used for designing drainage systems and to perform risk analyses. The parameters and noise statistics of the SDE are calibrated on time series of water table depths by embedding the SDE in a Kaiman filter algorithm and using the filter innovations in a filter-type maximum likelihood criterion. The stochastic model is calibrated and validated at two locations: a peat soil with a very shallow water table and a loamy sand soil with a moderately shallow water table. It is shown in both cases that sample functions simulated with the SDE are able to reproduce a wide range of statistics of water table depth. Despite its unrealistic assumption of constant inputs, the stationary solution derived from the Fokker-Planck equation gives good results for the peat soil, most likely because the characteristic response time of the water table is very small.

  3. Simulation of upward flux from shallow water-table using UPFLOW model

    Directory of Open Access Journals (Sweden)

    M. H. Ali

    2013-11-01

    Full Text Available The upward movement of water by capillary rise from shallow water-table to the root zone is an important incoming flux. For determining exact amount of irrigation requirement, estimation of capillary flux or upward flux is essential. Simulation model can provide a reliable estimate of upward flux under variable soil and climatic conditions. In this study, the performance of model UPFLOW to estimate upward flux was evaluated. Evaluation of model performance was performed with both graphical display and statistical criteria. In distribution of simulated capillary rise values against observed field data, maximum data points lie around the 1:1 line, which means that the model output is reliable and reasonable. The coefficient of determination between observed and simulated values was 0.806 (r = 0.93, which indicates a good inter-relation between observed and simulated values. The relative error, model efficiency, and index of agreement were found as 27.91%, 85.93% and 0.96, respectively. Considering the graphical display of observed and simulated upward flux and statistical indicators, it can be concluded that the overall performance of the UPFLOW model in simulating actual upward flux from a crop field under variable water-table condition is satisfactory. Thus, the model can be used to estimate capillary rise from shallow water-table for proper estimation of irrigation requirement, which would save valuable water from over-irrigation.

  4. Modelling mid-span water table depth and drainage discharge ...

    African Journals Online (AJOL)

    2015-04-03

    Apr 3, 2015 ... addition, the time requirements for this method make it unsuit- able for agricultural .... auger smeared the surface of the auger-hole during the drilling process. ... which water level readings were taken every 10 s, using a Laser.

  5. Modelling contrasting responses of wetland productivity to changes in water table depth

    Directory of Open Access Journals (Sweden)

    R. F. Grant

    2012-11-01

    Full Text Available Responses of wetland productivity to changes in water table depth (WTD are controlled by complex interactions among several soil and plant processes, and hence are site-specific rather than general in nature. Hydrological controls on wetland productivity were studied by representing these interactions in connected hummock and hollow sites in the ecosystem model ecosys, and by testing CO2 and energy fluxes from the model with those measured by eddy covariance (EC during years with contrasting WTD in a shrub fen at Lost Creek, WI. Modelled interactions among coupled processes for O2 transfer, O2 uptake, C oxidation, N mineralization, N uptake and C fixation by diverse microbial, root and mycorrhizal populations enabled the model to simulate complex responses of CO2 exchange to changes in WTD that depended on the WTD at which change was occurring. At the site scale, greater WTD caused the model to simulate greater CO2 influxes and effluxes over hummocks vs. hollows, as has been found at field sites. At the landscape scale, greater WTD caused the model to simulate greater diurnal CO2 influxes and effluxes under cooler weather when water tables were shallow, but also smaller diurnal CO2 influxes and effluxes under warmer weather when water tables were deeper, as was also apparent in the EC flux measurements. At an annual time scale, these diurnal responses to WTD in the model caused lower net primary productivity (NPP and heterotrophic respiration (Rh, but higher net ecosystem productivity (NEP = NPP − Rh, to be simulated in a cooler year with a shallower water table than in a warmer year with a deeper one. This difference in NEP was consistent with those estimated from gap-filled EC fluxes in years with different water tables at Lost Creek and at similar boreal fens elsewhere. In sensitivity tests of the model, annual NEP

  6. Modelling contrasting responses of wetland productivity to changes in water table depth

    Directory of Open Access Journals (Sweden)

    R. F. Grant

    2012-05-01

    Full Text Available Responses of wetland productivity to changes in water table depth (WTD are controlled by complex interactions among several soil and plant processes, and hence are site-specific rather than general in nature. Hydrological controls on wetland productivity were studied by representing these interactions in connected hummock and hollow sites in the ecosystem model ecosys, and by testing CO2 and energy fluxes from the model with those measured by eddy covariance (EC during years with contrasting WTD in a shrub fen at Lost Creek, WI. Modelled interactions among coupled processes for O2 transfer, O2 uptake, C oxidation, N mineralization, N uptake and C fixation by diverse microbial, root, mycorrhizal and shoot populations enabled the model to simulate complex responses of CO2 exchange to changes in WTD that depended on the WTD at which change was occurring. At the site scale, greater WTD caused the model to simulate greater CO2 influxes and effluxes over hummocks vs. hollows, as has been found at field sites. At the landscape scale, greater WTD caused the model to simulate greater diurnal CO2 influxes and effluxes under cooler weather when water tables were shallow, but also smaller diurnal CO2 influxes and effluxes under warmer weather when water tables were deeper, as was also apparent in the EC flux measurements. At an annual time scale, these diurnal responses to WTD in the model caused lower net primary productivity (NPP and heterotrophic respiration (Rh, but higher net ecosystem productivity (NEP = NPP – Rh, to be simulated in a cooler year with a shallower water table than in a warmer year with a deeper one. This difference in NEP was consistent with those estimated from gap-filled EC fluxes in years with different water tables at Lost Creek and at similar boreal fens elsewhere. In sensitivity test of the model, annual NEP

  7. Simulating streamflow and water table depth with a coupled hydrological model

    Institute of Scientific and Technical Information of China (English)

    Alphonce Chenjerayi GUZHA; Thomas Byron HARDY

    2010-01-01

    A coupled model integrating MODFLOW and TOPNET with the models interacting through the exchange of recharge and baseflow and river-aquifer interactions was developed and applied to the Big Darby Watershed in Ohio,USA.Calibration and validation results show that there is generally good agreement between measured streamflow and simulated results from the coupled model.At two gauging stations,average goodness of fit(R2),percent bias(PB),and Nash Sutcliffe efficiency(ENS)values of 0.83,11.15%,and 0.83,respectively,were obtained for simulation of streamflow during calibration,and values of 0.84,8.75%,and 0.85,respectively,were obtained for validation.The simulated water table depths yielded average R2 values of 0.77and 0.76 for calibration and validation,respectively.The good match between measured and simulated streamflows and water table depths demonstrates that the model is capable of adequately simulating streamflows and water table depths in the watershed and also capturing the influence of spatial and temporal variation in recharge.

  8. Enhanced migratory waterfowl distribution modeling by inclusion of depth to water table data.

    Directory of Open Access Journals (Sweden)

    Betty J Kreakie

    Full Text Available In addition to being used as a tool for ecological understanding, management and conservation of migratory waterfowl rely heavily on distribution models; yet these models have poor accuracy when compared to models of other bird groups. The goal of this study is to offer methods to enhance our ability to accurately model the spatial distributions of six migratory waterfowl species. This goal is accomplished by creating models based on species-specific annual cycles and introducing a depth to water table (DWT data set. The DWT data set, a wetland proxy, is a simulated long-term measure of the point either at or below the surface where climate and geological/topographic water fluxes balance. For species occurrences, the USGS' banding bird data for six relatively common species was used. Distribution models are constructed using Random Forest and MaxEnt. Random Forest classification of habitat and non-habitat provided a measure of DWT variable importance, which indicated that DWT is as important, and often more important, to model accuracy as temperature, precipitation, elevation, and an alternative wetland measure. MaxEnt models that included DWT in addition to traditional predictor variables had a considerable increase in classification accuracy. Also, MaxEnt models created with DWT often had higher accuracy when compared with models created with an alternative measure of wetland habitat. By comparing maps of predicted probability of occurrence and response curves, it is possible to explore how different species respond to water table depth and how a species responds in different seasons. The results of this analysis also illustrate that, as expected, all waterfowl species are tightly affiliated with shallow water table habitat. However, this study illustrates that the intensity of affiliation is not constant between seasons for a species, nor is it consistent between species.

  9. Vertical radar profiles for the calibration of unsaturated flow models under dynamic water table conditions

    Science.gov (United States)

    Cassiani, G.; Gallotti, L.; Ventura, V.; Andreotti, G.

    2003-04-01

    The identification of flow and transport characteristics in the vadose zone is a fundamental step towards understanding the dynamics of contaminated sites and the resulting risk of groundwater pollution. Borehole radar has gained popularity for the monitoring of moisture content changes, thanks to its apparent simplicity and its high resolution characteristics. However, cross-hole radar requires closely spaced (a few meters), plastic-cased boreholes, that are rarely available as a standard feature in sites of practical interest. Unlike cross-hole applications, Vertical Radar Profiles (VRP) require only one borehole, with practical and financial benefits. High-resolution, time-lapse VRPs have been acquired at a crude oil contaminated site in Trecate, Northern Italy, on a few existing boreholes originally developed for remediation via bioventing. The dynamic water table conditions, with yearly oscillations of roughly 5 m from 6 to 11 m bgl, offers a good opportunity to observe via VRP a field scale drainage-imbibition process. Arrival time inversion has been carried out using a regularized tomographic algorithm, in order to overcome the noise introduced by first arrival picking. Interpretation of the vertical profiles in terms of moisture content has been based on standard models (Topp et al., 1980; Roth et al., 1990). The sedimentary sequence manifests itself as a cyclic pattern in moisture content over most of the profiles. We performed preliminary Richards' equation simulations with time varying later table boundary conditions, in order to estimate the unsaturated flow parameters, and the results have been compared with laboratory evidence from cores.

  10. Holes in the Bathtub: Water Table Dependent Services and Threshold Behavior in an Economic Model of Groundwater Extraction

    Science.gov (United States)

    Kirk-lawlor, N. E.; Edwards, E. C.

    2012-12-01

    In many groundwater systems, the height of the water table must be above certain thresholds for some types of surface flow to exist. Examples of flows that depend on water table elevation include groundwater baseflow to river systems, groundwater flow to wetland systems, and flow to springs. Meeting many of the goals of sustainable water resource management requires maintaining these flows at certain rates. Water resource management decisions invariably involve weighing tradeoffs between different possible usage regimes and the economic consequences of potential management choices are an important factor in these tradeoffs. Policies based on sustainability may have a social cost from forgoing present income. This loss of income may be worth bearing, but should be well understood and carefully considered. Traditionally, the economic theory of groundwater exploitation has relied on the assumption of a single-cell or "bathtub" aquifer model, which offers a simple means to examine complex interactions between water user and hydrologic system behavior. However, such a model assumes a closed system and does not allow for the simulation of groundwater outflows that depend on water table elevation (e.g. baseflow, springs, wetlands), even though those outflows have value. We modify the traditional single-cell aquifer model by allowing for outflows when the water table is above certain threshold elevations. These thresholds behave similarly to holes in a bathtub, where the outflow is a positive function of the height of the water table above the threshold and the outflow is lost when the water table drops below the threshold. We find important economic consequences to this representation of the groundwater system. The economic value of services provided by threshold-dependent outflows (including non-market value), such as ecosystem services, can be incorporated. The value of services provided by these flows may warrant maintaining the water table at higher levels than would

  11. Space-time modeling of water table depth using a regionalized time series model and the Kalman filter

    NARCIS (Netherlands)

    Bierkens, M.F.P.; Knotters, M.; Hoogland, T.

    2001-01-01

    Water authorities in the Netherlands are not only responsible for managing surface water, but also for managing the groundwater reserves. Particularly the water table depth is an important variable, determining agricultural production and the potential for nature development. Knowledge of the spatio

  12. Sand and Water Table Play

    Science.gov (United States)

    Wallace, Ann H.; White, Mary J.; Stone, Ryan

    2010-01-01

    The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…

  13. Sand and Water Table Play

    Science.gov (United States)

    Wallace, Ann H.; White, Mary J.; Stone, Ryan

    2010-01-01

    The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…

  14. Modeling relationships between water table depth and peat soil carbon loss in Southeast Asian plantations

    Science.gov (United States)

    Carlson, Kimberly M.; Goodman, Lael K.; May-Tobin, Calen C.

    2015-07-01

    Plantation-associated drainage of Southeast Asian peatlands has accelerated in recent years. Draining exposes the upper peat layer to oxygen, leading to elevated decomposition rates and net soil carbon losses. Empirical studies indicate positive relationships between long-term water table (WT) depth and soil carbon loss rate in peatlands. These correlations potentially enable using WT depth as a proxy for soil carbon losses from peatland plantations. Here, we compile data from published research assessing WT depth and carbon balance in tropical plantations on peat. We model net carbon loss from subsidence studies, as well as soil respiration (heterotrophic and total) from closed chamber studies, as a function of WT depth. WT depth across all 12 studies and 59 sites is 67 ± 20 cm (mean ± standard deviation). Mean WT depth is positively related to net carbon loss, as well as soil respiration rate. Our models explain 45% of net carbon loss variation and 45-63% of soil respiration variation. At a 70 cm WT depth, the subsidence model suggests net carbon loss of 20 tC ha-1 yr-1 (95% confidence interval (CI) 18-22 tC ha-1 yr-1) for plantations drained for >2 yr. Closed chamber-measured total soil respiration at this depth is 20 tC-CO2 ha-1 yr-1 (CI 17-24 tC-CO2 ha-1 yr-1) while heterotrophic respiration is 17 tC-CO2 ha-1 yr-1 (CI 14-20 tC-CO2 ha-1 yr-1), ˜82% of total respiration. While land use is not a significant predictor of soil respiration, WT depths are greater at acacia (75 ± 16 cm) than oil palm (59 ± 15 cm) sample sites. Improved spatio-temporal sampling of the full suite of peat soil carbon fluxes—including fluvial carbon export and organic fertilizer inputs—will clarify multiple mechanisms leading to carbon loss and gain, supporting refined assessments of the global warming potential of peatland drainage.

  15. Water-table contours of Nevada

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of water-table contours for Nevada. These data were created as part of an effort to provide statewide information on water table and depth to...

  16. Modelling the effects of porous media deformation on the propagation of water-table waves in a sandy unconfined aquifer

    Science.gov (United States)

    Jazayeri Shoushtari, Seyed Mohammad Hossein; Cartwright, Nick

    2016-11-01

    This paper examines the influence of porous media deformation on water-table wave dispersion in an unconfined aquifer using a numerical model which couples Richards' equation to the poro-elastic model. The study was motivated by the findings of Shoushtari et al. (J Hydrol 533:412-440, 2016) who were unable to reproduce the observed wave dispersion in their sand flume data with either numerical Richards' equation models (assuming rigid porous media) or existing analytic solutions. The water-table wave dispersion is quantified via the complex wave number extracted from the predicted amplitude and phase profiles. A sensitivity analysis was performed to establish the influence of the main parameters in the poro-elastic model, namely Young's modulus (E) and Poisson's ratio (ν). For a short oscillation period (T = 16.4 s), the phase lag increase rate (k i) is sensitive to the chosen values of E and ν, demonstrating an inverse relationship with both parameters. Changes in the amplitude decay rate (k r), however, were negligible. For a longer oscillation period (T = 908.6 s), variations in the values of E and ν resulted in only small changes in both k r and k i. In both the short and long period cases, the poro-elastic model is unable to reproduce the observed wave dispersion in the existing laboratory data. Hence porous media deformation cannot explain the additional energy dissipation in the laboratory data. Shoushtari SMH, Cartwright N, Perrochet P, Nielsen P (2016) The effects of oscillation period on groundwater wave dispersion in a sandy unconfined aquifer: sand flume experiments and modelling. J Hydrol 533:412-440.

  17. Modelling the effects of porous media deformation on the propagation of water-table waves in a sandy unconfined aquifer

    Science.gov (United States)

    Jazayeri Shoushtari, Seyed Mohammad Hossein; Cartwright, Nick

    2017-03-01

    This paper examines the influence of porous media deformation on water-table wave dispersion in an unconfined aquifer using a numerical model which couples Richards' equation to the poro-elastic model. The study was motivated by the findings of Shoushtari et al. (J Hydrol 533:412-440, 2016) who were unable to reproduce the observed wave dispersion in their sand flume data with either numerical Richards' equation models (assuming rigid porous media) or existing analytic solutions. The water-table wave dispersion is quantified via the complex wave number extracted from the predicted amplitude and phase profiles. A sensitivity analysis was performed to establish the influence of the main parameters in the poro-elastic model, namely Young's modulus ( E) and Poisson's ratio ( ν). For a short oscillation period ( T = 16.4 s), the phase lag increase rate ( k i) is sensitive to the chosen values of E and ν, demonstrating an inverse relationship with both parameters. Changes in the amplitude decay rate ( k r), however, were negligible. For a longer oscillation period ( T = 908.6 s), variations in the values of E and ν resulted in only small changes in both k r and k i. In both the short and long period cases, the poro-elastic model is unable to reproduce the observed wave dispersion in the existing laboratory data. Hence porous media deformation cannot explain the additional energy dissipation in the laboratory data. Shoushtari SMH, Cartwright N, Perrochet P, Nielsen P (2016) The effects of oscillation period on groundwater wave dispersion in a sandy unconfined aquifer: sand flume experiments and modelling. J Hydrol 533:412-440.

  18. MCNPX Model/Table Comparison

    Energy Technology Data Exchange (ETDEWEB)

    J.S. Hendricks

    2003-03-03

    MCNPX is a Monte Carlo N-Particle radiation transport code extending the capabilities of MCNP4C. As with MCNP, MCNPX uses nuclear data tables to transport neutrons, photons, and electrons. Unlike MCNP, MCNPX also uses (1) nuclear data tables to transport protons; (2) physics models to transport 30 additional particle types (deuterons, tritons, alphas, pions, muons, etc.); and (3) physics models to transport neutrons and protons when no tabular data are available or when the data are above the energy range (20 to 150 MeV) where the data tables end. MCNPX can mix and match data tables and physics models throughout a problem. For example, MCNPX can model neutron transport in a bismuth germinate (BGO) particle detector by using data tables for bismuth and oxygen and using physics models for germanium. Also, MCNPX can model neutron transport in UO{sub 2}, making the best use of physics models and data tables: below 20 MeV, data tables are used; above 150 MeV, physics models are used; between 20 and 150 MeV, data tables are used for oxygen and models are used for uranium. The mix-and-match capability became available with MCNPX2.5.b (November 2002). For the first time, we present here comparisons that calculate radiation transport in materials with various combinations of data charts and model physics. The physics models are poor at low energies (<150 MeV); thus, data tables should be used when available. Our comparisons demonstrate the importance of the mix-and-match capability and indicate how well physics models work in the absence of data tables.

  19. MCNPX Model/Table Comparison

    CERN Document Server

    Hendricks, J S

    2003-01-01

    MCNPX is a Monte Carlo N-Particle radiation transport code extending the capabilities of MCNP4C. As with MCNP, MCNPX uses nuclear data tables to transport neutrons, photons, and electrons. Unlike MCNP, MCNPX also uses (1) nuclear data tables to transport protons; (2) physics models to transport 30 additional particle types (deuterons, tritons, alphas, pions, muons, etc.); and (3) physics models to transport neutrons and protons when no tabular data are available or when the data are above the energy range (20 to 150 MeV) where the data tables end. MCNPX can mix and match data tables and physics models throughout a problem. For example, MCNPX can model neutron transport in a bismuth germinate (BGO) particle detector by using data tables for bismuth and oxygen and using physics models for germanium. Also, MCNPX can model neutron transport in UO sub 2 , making the best use of physics models and data tables: below 20 MeV, data tables are used; above 150 MeV, physics models are used; between 20 and 150 MeV, data t...

  20. Modelling effects of seasonal variation in water table depth on net ecosystem CO2 exchange of a tropical peatland

    Directory of Open Access Journals (Sweden)

    M. Mezbahuddin

    2013-08-01

    Full Text Available Seasonal variation in water table depth (WTD determines the balance between aggradation and degradation of tropical peatlands. Longer dry seasons together with human interventions (e.g. drainage can cause WTD drawdowns making tropical peatland C storage highly vulnerable. Better predictive capacity for effects of WTD on net CO2 exchange is thus essential to guide conservation of tropical peat deposits. Mathematical modelling of basic eco-hydrological processes under site-specific conditions can provide such predictive capacity. We hereby deploy a mathematical model ecosys to study effects of seasonal variation in WTD on net ecosystem productivity (NEP of an Indonesian peatland. We simulated lower NEPs (~ –2 g C m–2 d–1 during rainy seasons with shallow WTD, higher NEPs (~ +1 g C m–2 d–1 during early dry seasons with intermediate WTD and again lower NEPs (~ –4 g C mm–2 d–1 during late dry seasons with deep WTD during 2002–2005. These values were corroborated by regressions (P 2 fluxes which yielded R2 > 0.8, intercepts approaching 0 and slopes approaching 1. We also simulated a gradual increase in annual NEPs from 2002 (−609 g C m–2 to 2005 (−373 g C m–2 with decreasing WTD which was corroborated by EC-gap filled annual NEP estimates. These WTD effects on NEP were modelled from basic eco-hydrological processes including microbial and root oxidation-reduction reactions driven by soil and root O2 transport and uptake which in turn drove soil and plant C, N and P transformations within a soil-plant-atmosphere water transfer scheme driven by water potential gradients. This modelling should therefore provide a predictive capacity for WTD management programs to reduce tropical peat degradation.

  1. Groundwater-soil moisture-climate interactions: lessons from idealized model experiments with forced water table depth

    Science.gov (United States)

    Ducharne, Agnès; Lo, Min-Hui; Decharme, Bertrand; Wang, Fuxing; Cheruy, Frédérique; Ghattas, Josefine; Chien, Rong-You; lan, Chia-Wei; Colin, Jeanne; Tyteca, Sophie

    2016-04-01

    Groundwater (GW) constitutes by far the largest volume of liquid freshwater on Earth. The most active part is soil moisture (SM), recognized as a key variable of land/atmosphere interactions, especially in so-called transition zones, where/when SM varies between wet and dry values. But GW can also be stored in deeper reservoirs than soils, in particular unconfined aquifer systems, in which the saturated part is called the water table (WT). The latter is characterized by slow and mostly horizontal water flows towards the river network, with well-known buffering effects on streamflow variability. Where/when the WT is shallow enough, it can also sustain SM by means of capillary rise, thus increase evapotranspiration (ET), with potential impact on the climate system (including temperatures and precipitation). The large residence time of GW may also increase the Earth system's memory, with consequences on the persistence of extreme events, hydro-climatic predictability, and anthropogenic climate change, particularly the magnitude of regional warming. Here, our main goal is to explore the potential impacts of the water table depth (WTD) on historical climate through idealized model analyses. To this end, we force three state-of-the art land surface models (LSMs), namely CLM, ORCHIDEE, and SURFEX, with prescribed WTDs ranging from 0.5 to 10 m. The LSMs are run either off-line or coupled to their parent climate model, following LMIP/AMIP-like protocols for intercomparability. Within this framework, we want to assess the sensitivity of ET and the simulated climate to the WTD in a systematic way. In particular, we will identify and compare the patterns of the critical WTD, defined as the deepest one to achieve a significant change in ET. To this end, we estimate derivatives of ET with respect to WTD, which tell how the sensitivity of ET to a unit change in WTD evolves with WTD. In each grid-point, these derivatives can be used to define the critical WTD, given a threshold ET

  2. Effect of the spatial distribution of physical aquifer properties on modelled water table depth and stream discharge in a headwater catchment

    Directory of Open Access Journals (Sweden)

    C. Gascuel-Odoux

    2010-07-01

    Full Text Available Water table depth and its dynamics on hillslopes are often poorly predicted despite they control both water transit time within the catchment and solute fluxes at the catchment outlet. This paper analyses how relaxing the assumption of lateral homogeneity of physical properties can improve simulations of water table depth and dynamics. Four different spatial models relating hydraulic conductivity to topography have been tested: a simple linear relationship, a linear relationship with two different topographic indexes, two Ks domains with a transitional area. The Hill-Vi model has been modified to test these hypotheses. The studied catchment (Kervidy-Naizin, Western France is underlain by schist crystalline bedrock. A shallow and perennial groundwater highly reactive to rainfall events mainly develops in the weathered saprolite layer. The results indicate that (1 discharge and the water table in the riparian zone are similarly predicted by the four models, (2 distinguishing two Ks domains constitutes the best model and slightly improves prediction of the water table upslope, and (3 including spatial variations in the other parameters such as porosity or rate of hydraulic conductivity decrease with depth does not improve the results. These results underline the necessity of better investigations of upslope areas in hillslope hydrology.

  3. Modelling Effects of Water Table Depth Variations on Net Ecosystem CO2 Exchange of a Western Canadian Peatland

    Science.gov (United States)

    Mezbahuddin, S.; Grant, R. F.; Flanagan, L. B.

    2014-12-01

    Water table depth (WTD) is one of the key drivers affecting aggradation and degradation of peatlands. Variations in WTD can alter the balance between gross primary productivity (GPP) and ecosystem respiration (Re) and so cause a peatland to change between a sink and a source of carbon. Process based mathematical modelling can provide insights on WTD-net ecosystem productivity (NEP) interactions over peatlands. We deployed a process-based ecosystem model ecosys to examine the WTD effects on variations in NEP of a fen peatland in Alberta, Canada. Our modelled results showed that a growing season (May-August) WTD drawdown of ~0.3m from 2004-2007 caused more rapid decomposition in deeper peat layers so that Re increased by ~180 g C m-2 growing season -1. However, similar increase in GPP (~ 170 g C m-2 growing season -1) under deeper WTD condition due to more rapid microbial and root growth, and hence more rapid mineralization and nutrient uptake, left no net effect of WTD drawdown on NEP. The modelled ecosystem was overall a large sink of C (~ 100 g C m-2 yr-1) over the study period of 2004-2009. However, gradually diminishing GPP by ~ 70 g C m-2 growing season -1 with progressively deeper WTD during 2008-2009 indicated that further drawdown of WTD could alter the source sink status of these peatlands. These modelled results were corroborated against hourly eddy covariance (EC) net CO2 fluxes, latent heat and sensible heat fluxes (R2~0.75, a→0, b→1); and annual estimates of EC-gap filled NEP and partitioned GPP and Re over the site from 2004-2009. Our findings indicated the needs for coupling of soil-plant-atmosphere schemes for gases, water, energy, carbon and nutrients in models to adequately simulate WTD effects on peatland C stocks.

  4. Modeling impacts of changes in temperature and water table on C gas fluxes in an Alaskan peatland

    Science.gov (United States)

    Deng, Jia; Li, Changsheng; Frolking, Steve

    2015-07-01

    Northern peatlands have accumulated a large amount of organic carbon (C) in their thick peat profile. Climate change and associated variations in soil environments are expected to have significant impacts on the C balance of these ecosystems, but the magnitude is still highly uncertain. Verifying and understanding the influences of changes in environmental factors on C gas fluxes in biogeochemical models are essential for forecasting feedbacks between C gas fluxes and climate change. In this study, we applied a biogeochemical model, DeNitrification-DeComposition (DNDC), to assess impacts of air temperature (TA) and water table (WT) on C gas fluxes in an Alaskan peatland. DNDC was validated against field measurements of net ecosystem exchange of CO2 (NEE) and CH4 fluxes under manipulated surface soil temperature and WT conditions in a moderate rich fen. The validation demonstrates that DNDC was able to capture the observed impacts of the manipulations in soil environments on C gas fluxes. To investigate responses of C gas fluxes to changes in TA and soil water condition, we conducted a series of simulations with varying TA and WT. The results demonstrate that (1) uptake rates of CO2 at the site were reduced by either too colder or warmer temperatures and generally increased with increasing soil moisture; (2) CH4 emissions showed an increasing trend as TA increased or WT rose toward the peat surface; and (3) the site could shift from a net greenhouse gas (GHG) sink into a net GHG source under some warm and/or dry conditions. A sensitivity analysis evaluated the relative importance of TA and WT to C gas fluxes. The results indicate that both TA and WT played important roles in regulating NEE and CH4 emissions and that within the investigated ranges of the variations in TA and WT, changes in WT showed a greater impact than changes in TA on NEE, CH4 fluxes, and net C gas fluxes at the study fen.

  5. Electrical imaging and fluid modeling of convective fingering in a shallow water-table aquifer

    Science.gov (United States)

    Dam, Remke L.; Eustice, Brian P.; Hyndman, David W.; Wood, Warren W.; Simmons, Craig T.

    2014-02-01

    Unstable density-driven flow can lead to enhanced solute transport in groundwater. Only recently has the complex fingering pattern associated with free convection been documented in field settings. Electrical resistivity (ER) tomography has been used to capture a snapshot of convective instabilities at a single point in time, but a thorough transient analysis is still lacking in the literature. We present the results of a 2 year experimental study at a shallow aquifer in the United Arab Emirates that was designed to specifically explore the transient nature of free convection. ER tomography data documented the presence of convective fingers following a significant rainfall event. We demonstrate that the complex fingering pattern had completely disappeared a year after the rainfall event. The observation is supported by an analysis of the aquifer halite budget and hydrodynamic modeling of the transient character of the fingering instabilities. Modeling results show that the transient dynamics of the gravitational instabilities (their initial development, infiltration into the underlying lower-density groundwater, and subsequent decay) are in agreement with the timing observed in the time-lapse ER measurements. All experimental observations and modeling results are consistent with the hypothesis that a dense brine that infiltrated into the aquifer from a surficial source was the cause of free convection at this site, and that the finite nature of the dense brine source and dispersive mixing led to the decay of instabilities with time. This study highlights the importance of the transience of free convection phenomena and suggests that these processes are more rapid than was previously understood.

  6. Water-table altitude of Nevada

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This is a raster-based, depth to ground-water data set for the State of Nevada. The source of this data set is a statewide water-table contour data set constructed...

  7. Accounting for intracell flow in models with emphasis on water table recharge and stream-aquifer interaction. 1. Problems and concepts

    Science.gov (United States)

    Jorgensen, D.G.; Signor, D.C.; Imes, J.L.

    1989-01-01

    One method of modeling multiple sources and sinks is to determine the net recharge per cell. For example, for a model cell containing both a sink and recharge through the water table, the amount of recharge should be reduced by the ratio of the area of influence of the sink within the cell to the area of the cell. The reduction is the intercepted portion of the recharge. In a multilayer model this amount is further reduced by a proportion factor, which is a function of the depth of the flow lines from the water table boundary to the internal sink. A gaining section of a stream is a typical sink. The aquifer contribution to a gaining stream can be conceptualized as having two parts; the first part is the intercepted lateral flow from the water table and the second is the flow across the streambed due to differences in head between the water level in the stream and the aquifer below. The amount intercepted is a function of the geometry of the cell, but the amount due to difference in head across the stream bed is largely independent of cell geometry. -from Authors

  8. Malheur NWR: Initial Survey Instructions for Water Table Depth Survey

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Water table wells assist in filling a critical information gap related to fluctuating water table depth and its influence on habitat expression within wet meadow...

  9. Geomorphological control of water tables in a blanket peat landscape: implications for carbon cycling

    Science.gov (United States)

    Allott, Tim; Evans, Martin; Lindsay, John; Agnew, Clive; Freer, Jim

    2010-05-01

    Water tables are an important control on carbon cycling and rates of carbon sequestration in peatland systems, and water table depth is therefore a key parameter in carbon models for blanket peat systems. Although there is a wide literature on blanket peat hydrology, including studies which specifically evaluate water table conditions, detailed data on water table behaviour and variability at the landscape scale are sparse. In particular, many British blanket peats are affected by gully erosion and this has been generally assumed to influence water table conditions. However, there has been limited evaluation of this geomomorphological control on peatland water tables. This paper presents results from a project which evaluated water table conditions in the blanket peatlands of the Peak District National Park, UK. A key aim was to quantify the impact of gully erosion on peatland water tables. A detailed programme of water table monitoring was undertaken during 2008/09, involving regular measurements of water table depth in over 530 dipwells at 19 sites across the 47 km2 peatland landscape of the Kinder Scout / Bleaklow area. This included a campaign of regular, simultaneous water table measurements from clusters of dipwells at the main sites, supplemented by continuous (hourly) water table monitoring in selected dipwells. It also included studies to evaluate within-site variation in water table conditions and local water table drawdown effects associated with gully erosion. Results indicate that gully erosion causes water table drawdown through two distinct processes. The first is local water table drawdown immediately adjacent to erosion gullies. This effect is restricted to a zone within 2 m of gully edges, and water tables within the gully edge drawdown zone are approximately 200 mm lower than in the adjacent peatland. The second effect is a more general water table lowering at eroded sites, with median water table depths at heavily eroded sites up to 300 mm lower

  10. VIDENTE: a graphical user interface and decision support system for stochastic modelling of water table fluctuations at a single location; includes documentation of the programs KALMAX, KALTFN, SSD and EMERALD and introductions to stochastic modellin

    NARCIS (Netherlands)

    Bierkens, M.F.P.; Bron, W.A.

    2000-01-01

    The VIDENTE program contains a decision support system (DSS) to choose between different models for stochastic modelling of water-table depths, and a graphical user interface to facilitate operating and running four implemented models: KALMAX, KALTFN,SSDS and EMERALD. In self-contained parts each of

  11. Links between climate change, water-table depth, and water chemistry in a mineralized mountain watershed

    Science.gov (United States)

    Manning, Andrew H.; Verplanck, Philip L.; Caine, Jonathan S.; Todd, Andrew S.

    2013-01-01

    Recent studies suggest that climate change is causing rising solute concentrations in mountain lakes and streams. These changes may be more pronounced in mineralized watersheds due to the sensitivity of sulfide weathering to changes in subsurface oxygen transport. Specific causal mechanisms linking climate change and accelerated weathering rates have been proposed, but in general remain entirely hypothetical. For mineralized watersheds, a favored hypothesis is that falling water tables caused by declining recharge rates allow an increasing volume of sulfide-bearing rock to become exposed to air, thus oxygen. Here, we test the hypothesis that falling water tables are the primary cause of an increase in metals and SO4 (100-400%) observed since 1980 in the Upper Snake River (USR), Colorado. The USR drains an alpine watershed geologically and climatologically representative of many others in mineralized areas of the western U.S. Hydrologic and chemical data collected from 2005 to 2011 in a deep monitoring well (WP1) at the top of the USR watershed are utilized. During this period, both water table depths and groundwater SO4 concentrations have generally increased in the well. A numerical model was constructed using TOUGHREACT that simulates pyrite oxidation near WP1, including groundwater flow and oxygen transport in both saturated and unsaturated zones. The modeling suggests that a falling water table could produce an increase in metals and SO4 of a magnitude similar to that observed in the USR (up to 300%). Future water table declines may produce limited increases in sulfide weathering high in the watershed because of the water table dropping below the depth of oxygen penetration, but may continue to enhance sulfide weathering lower in the watershed where water tables are shallower. Advective air (oxygen) transport in the unsaturated zone caused by seasonally variable recharge and associated water table fluctuations was found to have little influence on pyrite

  12. Water Table Dynamics of a Rocky Mountain Riparian Area

    Science.gov (United States)

    Westbrook, C. J.

    2009-05-01

    Riparian areas in mountain valleys serve as collection points for local precipitation, hillslope runoff, deeper groundwater, and channel water. Little is known about how complex hydrological interactions among these water sources govern riparian water table dynamics, particularly on an event basis partly owing to a lack of high frequency spatial and temporal data. Herein I describe the magnitude and rate of change of groundwater storage in a 1.3 km2 Canadian Rocky Mountain peat riparian area. Weekly manual measurement of hydraulic heads in a network of 51 water table wells during the summers of 2006 and 2007 showed large temporal and spatial variations in well response. A near constant increase in the spatial heterogeneity of the water table was observed as the riparian area dried. Cluster analysis and principle components analysis were performed on these weekly data to objectively classify the riparian area into spatial response units. Results were classification of the standpipes into five distinct water table regimes. One well representing each water table regime was outfitted with a sensor in 2008 that measured hourly head, which was used to characterize temporal dynamics of water table response. In spring, snowmelt runoff combined with an ice lens 20-30 cm below the ground surface led to consistently high water tables throughout the riparian area. In summer, the water table fell throughout the riparian in response to declining hillslope inputs and increased evaporative demand, but rates of decline were highly variable among the water table regimes. Chloride concentrations suggest variability reflects differences in the degree to which the water table regimes are influenced by stream stage, hillslope inputs, and proximity to beaver dams. Water table regime responses to rain events were flashy, with dramatic rises and falls (up to 20 cm) in short periods of time (export and plant community composition.

  13. Potential for water-table excursions induced by seismic events at Yucca Mountain, Nevada

    Science.gov (United States)

    Carrigan, Charles R.; King, Geoffrey C. P.; Barr, George E.; Bixler, Nathan E.

    1991-12-01

    The possibility that 100-200 m changes in water-table elevation can be mechanically induced by earthquakes is a consideration in site studies of a potential high-level nuclear waste repository at Yucca Mountain, Nevada. However, numerical simulations of tectonohydrologic coupling involving earthquakes typical of the Basin and Range province produce 2-3 m excursions of a water table that is 500 m below the land surface. Even displacements corresponding to extraordinary seismic events drive water-table excursions of less than 20 m. Flow resulting from earthquake-induced pore-pressure fields below the water table tends to be mainly horizontal; vertical flows that cause changes of the level of the water table are secondary. Strongly anisotropic permeability, intended to enhance vertical flow within fault zones, only doubles water-table rise in the models considered. These simulations of water-table rise compare well with observations following large earthquakes in the Basin and Range. Our models suggest that exceptional hydrologic and/or tectonic conditions would be required to produce substantially larger water-table rises.

  14. A GRACE-Streamflow Land Surface Model Calibration Approach for Improved Baseflow and Water Table Simulations over the Highly Managed Upper-Nile Basin of East Africa

    Science.gov (United States)

    Nanteza, J.; Lo, M. H.; Wu, R. J.; Thomas, B. F.; Famiglietti, J. S.

    2015-12-01

    Land surface models (LSMs) are useful tools for understanding behaviors of land hydrologic variables at different time and spatial scales. LSM outputs, however, are marked with great uncertainties resulting from the simplified assumptions on the parameterization and processes of the land surface and a poor representation of both the natural and anthropogenic controls on the system. The Upper-Nile basin, over Uganda, Kenya and Tanzania, is one region that is characteristic of significant human controls on streamflow, including Lake Victoria releases. The river Nile flow from Lake Victoria follows apriori rating curves that are not simulated by LSMs. Apart from management practices; the huge storage volume of Lake Victoria also modifies the seasonal characteristics of the Upper-Nile discharge, creating small seasonal variations in stream flow. In this study we calibrate several critical parameters in the Community Land Model (CLM.v4) in a multiobjective framework using total water storage anomalies (∆TWS) from GRACE, observed total runoff (Q) and estimated baseflow (BF) over the Upper-Nile basin. The goal is to improve the CLM parameters so that the model simulates the agreed curve (apriori) streamflow and baseflow with a better accuracy. We demonstrate the significance of improved parametrization by comparing model results of ∆TWS, Q and BF with a combination of insitu and estimated observations. Preliminary results based on RMSE statistics show that with calibration, simulations of ∆TWS, Q and BF achieve higher performance. Further, an improvement in the model's capacity to simulate the water table depth is also evident with the calibration. Such results provide a basis for using CLM for other hydrologic experiments that could guide water resources management in this highly managed basin.

  15. Decreased summer water table depth affects peatland vegetation

    NARCIS (Netherlands)

    Breeuwer, A.J.G.; Robroek, B.J.M.; Limpens, J.; Heijmans, M.M.P.D.; Schouten, M.G.C.; Berendse, F.

    2009-01-01

    Climate change can be expected to increase the frequency of summer droughts and associated low water tables in ombrotrophic peatlands. We studied the effects of periodic water table drawdown in a mesocosm experiment. Mesocosms were collected in Southern Sweden, and subsequently brought to an

  16. Decreased summer water table depth affects peatland vegetation

    NARCIS (Netherlands)

    Breeuwer, A.J.G.; Robroek, B.J.M.; Limpens, J.; Heijmans, M.M.P.D.; Schouten, M.G.C.; Berendse, F.

    2009-01-01

    Climate change can be expected to increase the frequency of summer droughts and associated low water tables in ombrotrophic peatlands. We studied the effects of periodic water table drawdown in a mesocosm experiment. Mesocosms were collected in Southern Sweden, and subsequently brought to an experim

  17. Significance testing testate amoeba water table reconstructions

    Science.gov (United States)

    Payne, Richard J.; Babeshko, Kirill V.; van Bellen, Simon; Blackford, Jeffrey J.; Booth, Robert K.; Charman, Dan J.; Ellershaw, Megan R.; Gilbert, Daniel; Hughes, Paul D. M.; Jassey, Vincent E. J.; Lamentowicz, Łukasz; Lamentowicz, Mariusz; Malysheva, Elena A.; Mauquoy, Dmitri; Mazei, Yuri; Mitchell, Edward A. D.; Swindles, Graeme T.; Tsyganov, Andrey N.; Turner, T. Edward; Telford, Richard J.

    2016-04-01

    Transfer functions are valuable tools in palaeoecology, but their output may not always be meaningful. A recently-developed statistical test ('randomTF') offers the potential to distinguish among reconstructions which are more likely to be useful, and those less so. We applied this test to a large number of reconstructions of peatland water table depth based on testate amoebae. Contrary to our expectations, a substantial majority (25 of 30) of these reconstructions gave non-significant results (P > 0.05). The underlying reasons for this outcome are unclear. We found no significant correlation between randomTF P-value and transfer function performance, the properties of the training set and reconstruction, or measures of transfer function fit. These results give cause for concern but we believe it would be extremely premature to discount the results of non-significant reconstructions. We stress the need for more critical assessment of transfer function output, replication of results and ecologically-informed interpretation of palaeoecological data.

  18. sir-06-5129_alt_water_table_con

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital geospatial data set consists of potentiometric contours that show lines of equal altitude of the generalized, long-term, regional water table in the...

  19. sir-06-5129_depth_water_table_con

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital geospatial data set consists of potentiometric contours that show lines of equal altitude of the generalized, long-term, regional water table in the...

  20. First solar models with OPAS opacity tables

    CERN Document Server

    Pennec, Maëlle Le; Salmon, Sébastien; Blancard, Christophe; Cossé, Philippe; Faussurier, Gérald; Mondet, Guillaume

    2015-01-01

    Stellar seismology appears more and more as a powerful tool for a better determination of the fundamental properties of solar-type stars. However the particular case of Sun is still challenging. The helioseismic sound speed determination continues to disagree with the Standard Solar Model (SSM) prediction for about a decade, questioning the reliability of this model. One of the sources of uncertainty could be in the treatment of the transport of radiation from the solar core to the surface. In this letter, we use the new OPAS opacity tables, recently available for solar modelling, to address this issue. We discuss first the peculiarities of these tables, then we quantify their impact on the solar sound speed and density profiles using the reduced OPAS tables taken on the grids of the OPAL ones. We use the two evolution codes MESA and CLES that led to similar conclusions in the solar radiative zone. In comparison to commonly used OPAL opacity tables, the new solar models computed, for the most recent photosphe...

  1. ESTIMATION OF WATER TABLE ELEVATION BY UNIVERSAL COKRIGING

    Institute of Scientific and Technical Information of China (English)

    CHEN Jia-jun; TIAN Kai-ming; GUO Qiao-yu

    2005-01-01

    When water resource or quality problems associated with phreatic water in geological settings are studied, information about water table elevations is often crucial.In those cases where the water table is a subdued replica of the ground surface, universal cokriging can be used to estimate water table elevations at un-sampled locations on the basis of water table and ground surface elevation measurements obtained at well locations.In this paper, universal cokriging, with ground surface elevation considered as a co-variate, was used to estimate water table elevations.Universal cokriging equations were derived, an iterative method for obtaining experimental variograms was established, and a case study of an initial groundwater flow simulation in the Xiuwu County, Henan Province, China, was presented.In the case study, the initial groundwater flow regime was represented both by universal cokriging with the ground surface elevation serving as a covariate and by universal kriging without the inclusion of ground surface elevation as a covariate.A comparison of the results from these two approaches shows that groundwater levels of phreatic water at locations without measurements in regions with unconsolidated porous media can be estimated more accurately by universal cokriging.

  2. Water-Table Levels and Gradients, Nevada, 1947-2004

    Science.gov (United States)

    Lopes, Thomas J.; Buto, Susan G.; Smith, J. LaRue; Welborn, Toby L.

    2006-01-01

    In 1999, the U.S. Environmental Protection Agency began a program to protect the quality of ground water in areas other than ground-water protection areas. These other sensitive ground water areas (OSGWA) are areas that are not currently, but could eventually be, used as a source of drinking water. The OSGWA program specifically addresses existing wells that are used for underground injection of motor-vehicle waste. To help determine whether a well is in an OSGWA, the Nevada Division of Environmental Protection needs statewide information on depth to water and the water table, which partly control the susceptibility of ground water to contamination and contaminant transport. This report describes a study that used available maps and data to create statewide maps of water-table and depth-to-water contours and surfaces, assessed temporal changes in water-table levels, and characterized water-table gradients in selected areas of Nevada. A literature search of published water-table and depth-to-water contours produced maps of varying detail and scope in 104 reports published from 1948 to 2004. Where multiple maps covered the same area, criteria were used to select the most recent, detailed maps that covered the largest area and had plotted control points. These selection criteria resulted in water-table and depth-to-water contours that are based on data collected from 1947 to 2004 being selected from 39 reports. If not already available digitally, contours and control points were digitized from selected maps, entered into a geographic information system, and combined to make a statewide map of water-table contours. Water-table surfaces were made by using inverse distance weighting to estimate the water table between contours and then gridding the estimates. Depth-to-water surfaces were made by subtracting the water-table altitude from the land-surface altitude. Water-table and depth-to-water surfaces were made for only 21 percent of Nevada because of a lack of

  3. Risk evaluation of ground water table decline as a type of desertification. A case study are: Southern Iran

    Energy Technology Data Exchange (ETDEWEB)

    Asrari, E.; Masoudi, M.

    2009-07-01

    This paper presents a model to assess risk of ground water table decline. Taking into consideration eleven indicators of lowering of ground water table the model identifies areas with Potential Risk (risky zones) and areas of Actual risk as well as projects the probability of the worse degradation in future. (Author) 7 refs.

  4. Water Tables, Flooding, and Water Use by Riparian Phreatophyte Communities

    Science.gov (United States)

    Thibault, J. R.; Cleverly, J. R.; Dahm, C.

    2010-12-01

    Phreatophytic riparian vegetation relies heavily on ground water transported from upstream sources. In the American southwest, the phenology of native phreatophytes, e.g., Rio Grande cottonwood, (Populus deltoides) is also dependent on seasonal flooding, which has been greatly diminished by hydrologic alterations and competing allocations. In this semi-arid, water-scarce region, a long history of agriculture and a rapidly expanding population impose limits on water available for ecological purposes, such as managed, restorative flooding. At native and non-native (e.g., saltcedar, (Tamarix spp.)) sites along the Rio Grande floodplain of central New Mexico, eddy covariance flux towers and monitoring wells are deployed to quantify evapotranspiration (ET) and investigate relationships between ET, water table (WT) depth, and flooding. Season-long measurements have been completed over several years in flooding and non-flooding sites under climatic conditions fluctuating from wet to extreme drought. Total growing season ET declines with deeper WTs across sites, with robust correlations where strong hydrologic connections exist between the river and ground water. As such, wet years with elevated WTs result in greater annual ET. However, ET responds less clearly to floods within the growing season. Longer duration floods lasting several weeks are more typical earlier in the growing season, associated with sufficient snowmelt runoff. Extensive spring flooding in two recent years coincided with significantly higher ET at a young, mixed stand, but had no effect on ET at a mature saltcedar forest. Summer monsoons and drier springs typically bring more transitory flood pulses with rapid WT ascent and decline measured in days. Elevated ET occurred during only one of several shorter flood pulses, at a saltcedar site during an otherwise dry spring. ET was not affected by monsoon flood pulses. Recruitment of native vegetation requires spring floods with favorable timing, magnitude

  5. Effects of long-term water table drawdown on evapotranspiration and vegetation in an arid region phreatophyte community

    Science.gov (United States)

    Cooper, David J.; Sanderson, John S.; Stannard, David I.; Groeneveld, David P.

    2006-06-01

    Evapotranspiration rates and the ground water component of evapotranspiration at a site in Colorado's San Luis Valley that is dominated by shrubby phreatophytes (greasewood and rabbitbrush) were compared before and after a water table drawdown. Evapotranspiration (ET) rates at the site were first measured in 1985-1987 (pre-drawdown) when the mean water table depth was 0.92 m. Regional ground water pumping has since lowered the water table by 1.58 m, to a mean of 2.50 m. We measured ET at the same site in 1999-2003 (post-drawdown), and assessed physical and biological factors affecting the response of ET to water table drawdown. Vegetation changed markedly from the pre-drawdown to the post-drawdown period as phreatophytic shrubs invaded former wetland areas, and wetland grasses and grass-like species decreased. Lowering the water table reduced estimated total annual ET from a mean of 409.0 to 278.0 mm, a decrease of 32%, and the ground water component of ET (ET g), from a mean of 226.6 to 86.5 mm, a decrease of 62%. Two water table depth/ET models that have been used in the San Luis Valley overestimated the reduction in ET g due to lowering the water table by as much as 253%. While our results corroborate the generally observed negative correlation between ET rates and water table depth, they demonstrate that specific models to estimate ET as a function of water table depth, if not verified, may be prone to large errors. Both the water table drawdown and the vegetation change are continuing 20 years after the drawdown began, and it is unclear how site ET rates and processes will differ after the water table has stabilized and vegetation has adjusted to the new site hydrologic conditions.

  6. EFFECT OF GROUNDWATER TABLE CONTROL ON WATER SAVING IRRIGATION STRATEGIES IN THE QINGTONGXIA IRRIGATION DISTRICT

    Institute of Scientific and Technical Information of China (English)

    WANG Xiu-gui; HOLLANDERS P. H. J.

    2004-01-01

    This paper focuses on the analysis of the effects of groundwater table control under different irrigation water amounts on the water and salinity balance and on crop yield. Two experimental areas, the Pingluo and Huinong experimental sites, were selected to collect the required data.The agro-hydrological model Soil-Water Atmosphere-Plant(SWAP) was used to analyse the water flows and salt transport processes for different groundwater levels and irrigation scenarios. Six scenarios, which resulted from different groundwater table regimes combined with different irrigation amounts, were simulated. The results show that high groundwater tables due to the excessive irrigation are the main cause of the large amount of drainage water and low crop yield;reducing irrigation water without a lower groundwater table will not lead to a large reduction of the drainage water, and will reduce the crop yield even more; to lower the groundwater table is a good measure to control the drainage water and increase crop yield.

  7. 基于人工神经网络模型的地下水水位动态变化模拟%Dynamic Variation Simulation of Ground Water Table Based on Artificial Neural Network Model

    Institute of Scientific and Technical Information of China (English)

    魏光辉

    2015-01-01

    Predication of the ground water table plays an important role in planning management of catchement surface and ground water resources.In this study, the artificial neural network model is applied in predication of the ground water table around the Xinier reser-voir.By application of data from 6 monitoring wells in the study area and of the artificial neural network model, the ground water table af-ter one week is predicated by simulation.The factors input the model include evaporation, reservoir level, escape canal level, water pumped volume and ground water table of the monitoring wells in last week.Therefore, the model is with 15 input points and 6 output points.Three different neural network methods of GDX, LM and BR methods are applied for the predication of the ground water table. The study shows that all three methods perform well in the predication.Generally, BR performance is better than these of GDX and LM. The artificial neural network model trained by BR method is applied for the predication of the ground water table in future 2nd, 3rd and 4th weeks in the study area.The simulation results are still better although the accuracy of the predication of the ground water table slight-ly decreases with time increment.%地下水水位的预测在流域地表水和地下水资源的综合规划管理中起着非常重要的作用。在该研究中,人工神经网络模型被应用于希尼尔水库周边地下水水位的预测中。采用研究区6口地下水观测井资料,用人工神经网络模型进行模拟预测1周后的地下水水位。模型输入因子包括此前1周蒸发量、水库水位、排渠水位、抽水量和观测井地下水位,因此模型有15个输入节点和6个输出节点。将3种不同的神经网络训练算法,即自适应学习速率动量梯度下降反向传播算法( GDX)、LM算法和贝叶斯正则化算法( BR)用于地下水水位预测,并对模拟结果进行了评估。结果表明:3种神经

  8. Modeling falling groundwater tables in major cities of the world

    Science.gov (United States)

    Sutanudjaja, Edwin; Erkens, Gilles

    2016-04-01

    Groundwater use and its over-consumption are one of the major drivers in the hydrology of many major cities in the world, particularly in delta regions. Yet, a global assessment to identify cities with declining groundwater table problems has not been done yet. In this study we used the global hydrological model PCR-GLOBWB (10 km resolution, for 1960-2010). Using this model, we globally calculated groundwater recharge and river discharge/surface water levels, as well as global water demand and abstraction from ground- and surface water resources. The output of PCR-GLOBWB model was then used to force a groundwater MODFLOW-based model simulating spatio-temporal groundwater head dynamics, including groundwater head declines in all major cities - mainly in delta regions - due to escalation in abstraction of groundwater to meet increasing water demand. Using these coupled models, we managed to identify a number of critical cities having groundwater table falling rates above 50 cm/year (average in 2000-2010), such as Barcelona, Houston, Los Angeles, Mexico City, New York, Rome and many large cities in China, Libya, India and Pakistan, as well as in Middle East and Central Asia regions. However, our simulation results overestimate the depletion rates in San Jose, Tokyo, Venice, and other cities where groundwater usages have been aggressively managed and replaced by importing surface water from other places. Moreover, our simulation might underestimate the declining groundwater head trends in some familiar cases, such as Bangkok (12 cm/year), Ho Chi Minh City (34 cm/year), and Jakarta (26 cm/year). The underestimation was due to an over-optimistic model assumption in allocating surface water for satisfying urban water needs. In reality, many big cities, although they are located in wet regions and have abundant surface water availability, still strongly rely on groundwater sources due to inadequate facilities to treat and distribute surface water resources.

  9. Mapping water table depth using geophysical and environmental variables.

    Science.gov (United States)

    Buchanan, S; Triantafilis, J

    2009-01-01

    Despite its importance, accurate representation of the spatial distribution of water table depth remains one of the greatest deficiencies in many hydrological investigations. Historically, both inverse distance weighting (IDW) and ordinary kriging (OK) have been used to interpolate depths. These methods, however, have major limitations: namely they require large numbers of measurements to represent the spatial variability of water table depth and they do not represent the variation between measurement points. We address this issue by assessing the benefits of using stepwise multiple linear regression (MLR) with three different ancillary data sets to predict the water table depth at 100-m intervals. The ancillary data sets used are Electromagnetic (EM34 and EM38), gamma radiometric: potassium (K), uranium (eU), thorium (eTh), total count (TC), and morphometric data. Results show that MLR offers significant precision and accuracy benefits over OK and IDW. Inclusion of the morphometric data set yielded the greatest (16%) improvement in prediction accuracy compared with IDW, followed by the electromagnetic data set (5%). Use of the gamma radiometric data set showed no improvement. The greatest improvement, however, resulted when all data sets were combined (37% increase in prediction accuracy over IDW). Significantly, however, the use of MLR also allows for prediction in variations in water table depth between measurement points, which is crucial for land management.

  10. Evaluation of a computer model to simulate water table response to subirrigation Avaliação de um modelo computacional para simular a resposta do lençol freático à subirrigação

    Directory of Open Access Journals (Sweden)

    Jadir Aparecido Rosa

    2002-12-01

    Full Text Available The objective of this work was to evaluate the water flow computer model, WATABLE, using experimental field observations on water table management plots from a site located near Hastings, FL, USA. The experimental field had scale drainage systems with provisions for subirrigation with buried microirrigation and conventional seepage irrigation systems. Potato (Solanum tuberosum L. growing seasons from years 1996 and 1997 were used to simulate the hydrology of the area. Water table levels, precipitation, irrigation and runoff volumes were continuously monitored. The model simulated the water movement from a buried microirrigation line source and the response of the water table to irrigation, precipitation, evapotranspiration, and deep percolation. The model was calibrated and verified by comparing simulated results with experimental field observations. The model performed very well in simulating seasonal runoff, irrigation volumes, and water table levels during crop growth. The two-dimensional model can be used to investigate different irrigation strategies involving water table management control. Applications of the model include optimization of the water table depth for each growth stage, and duration, frequency, and rate of irrigation.O objetivo deste trabalho foi avaliar o modelo computacional WATABLE usando-se dados de campo obtidos em uma área experimental em manejo de lençol freático, localizada em Hastings, FL, EUA. Na área experimental, estavam instalados um sistema de drenagem e sistemas de irrigação por subsuperfície com irrigação localizada e por canais. Ciclos de cultivo de batata (Solanum tuberosum L., nos anos de 1996 e 1997, foram usados para a simulação da hidrologia da área. Profundidades do lençol freático, chuvas, irrigação e escorrimento superficial foram monitorados constantemente. O modelo simulou o movimento da água a partir de uma linha de irrigação localizada enterrada, e a resposta do nível do len

  11. Interactions of carbon and water cycles in north temperate wetlands: Modeling and observing the impact of a declining water table trend on regional biogeochemistry

    Science.gov (United States)

    Benjamin N. Sulman; Ankur R. Desai; D.S. Mackay; S. Samanta; B.D. Cook; N. Saliendra

    2008-01-01

    Terrestrial carbon fluxes represent a major source of uncertainty in estimates of future atmospheric greenhouse gas accumulation and consequently models of climate change. In the Upper Great Lakes states (Minnesota, Wisconsin, and Michigan), wetlands cover 14% of the land area, and compose up to one third of the land cover in the forest-wetland landscapes that dominate...

  12. A new method to dynamically simulate groundwater table in land surface model VIC

    Institute of Scientific and Technical Information of China (English)

    YANG Hongwei; XIE Zhenghui

    2003-01-01

    Soil moisture plays an important role in water and energy balance in land-atmospheric interaction, but is impacted directly by the groundwater table. Dynamic variation of the groundwater table can be described mathematically by a moving boundary problem. In this paper, the moving boundary problem is reduced to a fixed boundary problem through a coordinate transformation. A new model of groundwater table simulation is developed using the mass-lumped finite element method and is coupled with the land surface model of Variable Infiltration Capacity (VIC). The simulation results show that the new model not only can simulate the groundwater table dynamically, but also can evade the choice of water table depth scale in computation with a low computation cost.

  13. Efficient water table evolution discretization using domain transformation

    DEFF Research Database (Denmark)

    Boon, W. M.; Balbarini, Nicola; Binning, Philip John

    2017-01-01

    Domain transformation methods are useful techniques for solving problems on non-stationary domains. In this work, we consider the evolution of the water table in an unconfined aquifer. This nonlinear, time-dependent problem is greatly simplified by using a mapping from the physical domain to a re...... to a reference domain and is then further reduced to a single, (nonlinear) partial differential equation. We show well-posedness of the approach and propose a stable and convergent discretization scheme. Numerical results are presented supporting the theory.......Domain transformation methods are useful techniques for solving problems on non-stationary domains. In this work, we consider the evolution of the water table in an unconfined aquifer. This nonlinear, time-dependent problem is greatly simplified by using a mapping from the physical domain...

  14. WATER TABLE AND REDOX CONDITIONS IN DEEP TROPICAL PEAT

    Institute of Scientific and Technical Information of China (English)

    Hajah Dulima Jali

    2007-01-01

    Redox potential in the well developed tropical peat swamp in Brunei was studied for a year. Generally the redox potential measurements showed a large variation, ranging from -234 mV to 727 mV. The expected rise in redox values did not take place following the drop of water table during the dry months of June to September. The redox value at 100 cm depth indicated that the soil remained reduced throughout the year in spite of the lowering of water table below 150 cm in all sites during dry period. Similarly the redox values did not decrease rapidly following flooding when the water table rose to the surface. This phenomenon could be attributed to the topography of the peat dome which facilitated the fast lateral movement of water and thus promoted oxygen supply down the peat profile, though not great enough to reach the 100 cm depth. The rapid lateral flow of water in the outer Alan batu site facilitated aeration, but in the inner sites remained which was reduced because of the slower water movement. The slower initiation of the reducing condition was likely due to the presence of nitrate which has accumulated as a result of ammonium oxidation during the relatively long aerobic period. Differences in the distribution of redox potential with depth are possibly explained by the different permeability of peat affecting flow patterns and residence time of water. The nature and compactibility of the peat might have slowed the diffusion rates of O2 into the lower layer. Though the bulk density of the peat was low, the composition of the peat might influence the peat permeability and hydraulic conductivity. The tree trunks are not decomposed or large branches must have lowered permeability compared to the other peat material.

  15. Coupling WRF with LEAFHYDRO: introducing groundwater and a fully dynamic water table in regional climate simulations

    Science.gov (United States)

    Martínez de La Torre, A.; Rios Entenza, A.; Gestal Souto, L.; Miguez Macho, G.

    2010-09-01

    Here we present a soil-vegetation-hydrology model, LEAFHYDRO coupled with the WRF model. LEAFHYDRO includes a groundwater parameterization with a dynamic water table and river routing and it can be run at a finer resolution than the atmosphere within WRF. Offline multiyear simulations over the Iberian Peninsula at 2.5 km resolution with the LEAFHYDRO model with and without groundwater indicate that introducing the water table parameterization has a significant impact on soil moisture amounts, soil moisture persistence and evapotranspiration fluxes. This is particularly true over the semiarid flat plateaus of the Iberian interior, where the atmospheric source of precipitation is scarce and the water table is naturally shallow due to slow drainage and lateral flow convergence from the surrounding mountains. Climatic simulations with the coupled WRF-HYDRO system suggest that the memory induced in the soil by the water table significantly impact the simulated precipitation, especially in the spring, when the land-surface atmospheric coupling is strong and rainfall amounts have their annual peak inland Iberia.

  16. Automated lab-scale visualization of the influence of water table transients on LNAPL source zone dynamics

    Science.gov (United States)

    SUN, S.; Herbert, A. W.; Rivett, M. O.

    2015-12-01

    For buoyant LNAPLs (Light Non-Aqueous Phase Liquids), fluctuating water table conditions significantly influence capillary-held mass above and below the water table and the quantity of mobile free product floating on the water table. Risks posed by such a dynamic LNAPL source zone vary over time as water tables oscillate from say tidal influences, seasonality or other anthropogenic influences. Whist LNAPL dynamics are evident at field scale, measurements of say LNAPL thickness variation in a well are not very revealing of the actual source zone dynamic nature and point to the importance of lab visualization and modelling studies. We report on the recently completed lab phase of our study in which 2-D sand tanks have been used to visualize hydrocarbon LNAPL redistribution under transient water table conditions, particularly cyclic oscillations. We have developed a fully automated system to: i) Program cyclic water table fluctuations via Raspberry PiTM based electronics; ii) Dynamically monitor the saturation distributions of all fluids (red-dyed-LNAPL, blue-dyed-water and air phase by difference) using high temporal frequency and spatial resolution multi-spectral photography; and iii) Efficiently interpret the imaged data produced via multi-spectral image analysis. Such automated data acquisition and processing has permitted the LNAPL release and its redistribution under oscillating water table conditions to be shown in vivid short video formats of original images and contoured fluid saturations. We present a series of these videos secured under a variety of sand-tank scenarios that aim to understand the controlling influences of fluctuation amplitude and frequency, the influence of lower permeability heterogeneities, and the significance of LNAPL release timing relative to water table position. Our preliminary interpretations of these data will be presented alongside our discussion of the implications for characterization and remediation of LNAPL contaminated sites

  17. Estimated Depth to Ground Water and Configuration of the Water Table in the Portland, Oregon Area

    Science.gov (United States)

    Snyder, Daniel T.

    2008-01-01

    Reliable information on the configuration of the water table in the Portland metropolitan area is needed to address concerns about various water-resource issues, especially with regard to potential effects from stormwater injection systems such as UIC (underground injection control) systems that are either existing or planned. To help address these concerns, this report presents the estimated depth-to-water and water-table elevation maps for the Portland area, along with estimates of the relative uncertainty of the maps and seasonal water-table fluctuations. The method of analysis used to determine the water-table configuration in the Portland area relied on water-level data from shallow wells and surface-water features that are representative of the water table. However, the largest source of available well data is water-level measurements in reports filed by well constructors at the time of new well installation, but these data frequently were not representative of static water-level conditions. Depth-to-water measurements reported in well-construction records generally were shallower than measurements by the U.S. Geological Survey (USGS) in the same or nearby wells, although many depth-to-water measurements were substantially deeper than USGS measurements. Magnitudes of differences in depth-to-water measurements reported in well records and those measured by the USGS in the same or nearby wells ranged from -119 to 156 feet with a mean of the absolute value of the differences of 36 feet. One possible cause for the differences is that water levels in many wells reported in well records were not at equilibrium at the time of measurement. As a result, the analysis of the water-table configuration relied on water levels measured during the current study or used in previous USGS investigations in the Portland area. Because of the scarcity of well data in some areas, the locations of select surface-water features including major rivers, streams, lakes, wetlands, and

  18. A Mathematical View of Water Table Fluctuations in a Shallow Aquifer in Brazil.

    Science.gov (United States)

    Neto, Dagmar C; Chang, Hung K; van Genuchten, Martinus Th

    2016-01-01

    Detailed monitoring of the groundwater table can provide important data about both short- and long-term aquifer processes, including information useful for estimating recharge and facilitating groundwater modeling and remediation efforts. In this paper, we presents results of 4 years (2002 to 2005) of monitoring groundwater water levels in the Rio Claro Aquifer using observation wells drilled at the Rio Claro campus of São Paulo State University in Brazil. The data were used to follow natural periodic fluctuations in the water table, specifically those resulting from earth tides and seasonal recharge cycles. Statistical analyses included methods of time-series analysis using Fourier analysis, cross-correlation, and R/S analysis. Relationships could be established between rainfall and well recovery, as well as the persistence and degree of autocorrelation of the water table variations. We further used numerical solutions of the Richards equation to obtain estimates of the recharge rate and seasonable groundwater fluctuations. Seasonable soil moisture transit times through the vadose zone obtained with the numerical solution were very close to those obtained with the cross-correlation analysis. We also employed a little-used deep drainage boundary condition to obtain estimates of seasonable water table fluctuations, which were found to be consistent with observed transient groundwater levels during the period of study.

  19. Numerical understanding of regional scale water table behavior in the Guadalupe Valley aquifer, Baja California, Mexico

    Directory of Open Access Journals (Sweden)

    J. R. Campos-Gaytan

    2006-05-01

    Full Text Available A regional groundwater flow model was developed, in order to evaluate the water table behavior in the region of the Guadalupe Valley, in Baja California, Mexico. The State of Baja California has been subject to an increment of the agricultural, urban and industrials activities, implicating a growing water-demand. However, the State is characterized by its semi-arid climate with low surface water availability; resulting in an extensive use of groundwater in local aquifer. Based on historic piezometric information of the last two decades, however, a negative evolution could be observed, resulting a negative storage volume. So far, there is not an integral hydrogeological evaluation that determine the real condition of the groundwater resource, and that permit to planning a management of the Guadalupe Valley Aquifer. A steady-state calibration model was carried out in order to obtain the best possible match to measured levels at the Guadalupe Valley Aquifer. The contours of calculated water table elevations for January 1983 were reproduced. Generally, the comparison of the observed and calculated water table configurations have a good qualitative and quantitatively adjustment. Nowadays, it is count with a hydrogeological model that can be used for simulates the groundwater flow in the region of the Guadalupe Valley.

  20. EFFECTS OF WATER TABLE AND NITROGEN ADDITION ON CO2 EMISSION FROM WETLAND SOIL

    Institute of Scientific and Technical Information of China (English)

    YANG Ji-song; LIU Jing-shuang; YU Jun-bao; WANG Jin-da; QIN Sheng-jin; LI Xin-hua

    2005-01-01

    Soil respiration is a main dynamic process of carbon cycle in wetland. It is important to contribute to global climate changes. Water table and nutritious availability are significant impact factors to influence responses of CO2 emission from wetland soil to climate changes. Twenty-four wetland soil monoliths at 4 water-table positions and in 3 nitrogen status have been incubated to measure rates of CO2 emission from wetland soils in this study.Three static water-table controls and a fluctuant water-table control, with 3 nitrogen additions in every water-table control,were carried out. In no nitrogen addition treatment, high CO2 emissions were found at a static low water table ( Ⅰ )and a fluctuant water table (Ⅳ),averaging 306.7mg/(m2·h) and 307.89mg/(m2·h), respectively, which were 51%-57% higher than that at static high water table ( Ⅱ and Ⅲ). After nitrogen addition, however, highest CO2 emission was found at Ⅱ and lowest emission at Ⅲ. The results suggested that nutritious availability of wetland soil might be important to influence the effect of water table on the CO2 emission from the wetland soil. Nitrogen addition led to enhancing CO2 emissions from wetland soil, while the highest emission was found in 1N treatments other than in 2N treatments. In 3 nutritious treatments,low CO2 emissions at high water tables and high CO2 emissions at low water tables were also observed when water table fluctuated. Our results suggested that both water table changes and nutritious imports would effect the CO2 emission from wetland.

  1. Remediation of NAPL below the water table by steam-induced heat conduction

    Science.gov (United States)

    Gudbjerg, J.; Sonnenborg, T. O.; Jensen, K. H.

    2004-08-01

    Previous experimental studies have shown that NAPL will be removed when it is contacted by steam. However, in full-scale operations, steam may not contact the NAPL directly and this is the situation addressed in this study. A two-dimensional intermediate scale sand box experiment was performed where an organic contaminant was emplaced below the water table at the interface between a coarse and a fine sand layer. Steam was injected above the water table and after an initial heating period the contaminant was recovered at the outlet. The experiment was successfully modeled using the numerical code T2VOC and the dominant removal mechanism was identified to be heat conduction induced boiling of the separate phase contaminant. Subsequent numerical modeling showed that this mechanism was insensitive to the porous medium properties and that it could be evaluated by considering only one-dimensional heat conduction.

  2. Water table effects on measured and simulated fluxes in weighing lysimeters for differently-textured soils

    Directory of Open Access Journals (Sweden)

    Wegehenkel Martin

    2015-03-01

    Full Text Available Weighing lysimeters can be used for studying the soil water balance and to analyse evapotranspiration (ET. However, not clear was the impact of the bottom boundary condition on lysimeter results and soil water movement. The objective was to analyse bottom boundary effects on the soil water balance. This analysis was carried out for lysimeters filled with fine- and coarse-textured soil monoliths by comparing simulated and measured data for lysimeters with a higher and a lower water table. The eight weighable lysimeters had a 1 m2 grass-covered surface and a depth of 1.5 m. The lysimeters contained four intact monoliths extracted from a sandy soil and four from a soil with a silty-clay texture. For two lysimeters of each soil, constant water tables were imposed at 135 cm and 210 cm depths. Evapotranspiration, change in soil water storage, and groundwater recharge were simulated for a 3-year period (1996 to 1998 using the Hydrus-1D software. Input data consisted of measured weather data and crop model-based simulated evaporation and transpiration. Snow cover and heat transport were simulated based on measured soil temperatures. Soil hydraulic parameter sets were estimated (i from soil core data and (ii based on texture data using ROSETTA pedotransfer approach. Simulated and measured outflow rates from the sandy soil matched for both parameter sets. For the sand lysimeters with the higher water table, only fast peak flow events observed on May 4, 1996 were not simulated adequately mainly because of differences between simulated and measured soil water storage caused by ET-induced soil water storage depletion. For the silty-clay soil, the simulations using the soil hydraulic parameters from retention data (i were matching the lysimeter data except for the observed peak flows on May, 4, 1996, which here probably resulted from preferential flow. The higher water table at the lysimeter bottom resulted in higher drainage in comparison with the lysimeters

  3. MODEL SELECTION FOR LOG-LINEAR MODELS OF CONTINGENCY TABLES

    Institute of Scientific and Technical Information of China (English)

    ZHAO Lincheng; ZHANG Hong

    2003-01-01

    In this paper, we propose an information-theoretic-criterion-based model selection procedure for log-linear model of contingency tables under multinomial sampling, and establish the strong consistency of the method under some mild conditions. An exponential bound of miss detection probability is also obtained. The selection procedure is modified so that it can be used in practice. Simulation shows that the modified method is valid. To avoid selecting the penalty coefficient in the information criteria, an alternative selection procedure is given.

  4. Optimization of irrigation water in stone fruit and table grapes

    Science.gov (United States)

    de la Rosa, Jose Mª; Castillo, Cristina; Temnani, Abdel; Pérez-Pastor, Alejandro

    2017-04-01

    In water scarcity areas, it must be highlighted that the maximum productions of the crops do not necessarily imply maximum profitability. Therefore, during the last years a special interest in the development of deficit irrigation strategies based on significant reductions of the seasonal ET without affecting production or quality has been observed. The strategies of regulated deficit irrigation (RDI) are based on the reduction of water supply during non critical periods, the covering of water needs during critical periods and maximizing, at the same time, the production by unit of applied water. The main objective of this experiment was to implement, demonstrate and disseminate a sustainable irrigation strategy based on deficit irrigation to promote its large scale acceptance and use in woody crops in Mediterranean agroecosystems, characterized by water scarcity, without affecting the quality standards demanded by exportation markets. Five demonstration plots were established in representative crops of the irrigating community of Campotejar (Murcia, Spain): i) Peach trees, cv. catherina in the "Periquitos" farm; ii) Apricot trees, cv. "Red Carlet" in "La Hoya del Fenazar" farm; iii) Nectarine trees, cv. Viowhite in "Agrícola Don Fernando" farm; iv) Table grape, cv "Crimson Seedless" in "La Hornera" farm; and v) Paraguayan cv. carioca in "The Hornera" farm. In each demonstration plot, at least two irrigation treatments were established: i) Control (CTL), irrigated to ensure non-limiting water conditions (120% of crop evapotranspiration) and ii) Regulated deficit irrigation (RDI) irrigated as CTL during critical periods and decreasing irrigation in non-critical periods. The plant water status indicators evaluated were midday stem water potential and Trunk Diameter Fluctuation derived indices: maximum daily shrinkage (MDS) and trunk daily growth rate (TGR); vegetative growth of the different crops from trunk diameter and pruning dry weight, fruit growth and fruit

  5. Upscaling of annual mean and dynamics of water table depth in German organic soils

    Science.gov (United States)

    Bechtold, Michel; Tiemeyer, Bärbel; Belting, Susanne; Laggner, Andreas; Leppelt, Thomas; Frahm, Enrico; Freibauer, Annette

    2013-04-01

    Water table depth is the key parameter controlling the fluxes of CO2, CH4 and N2O from organic soils (peatlands and other organic soils). Therefore, a good estimation of the spatial distribution of water table depth is crucial in any upscaling approach for these greenhouse gases (GHGs). It is further the prerequisite to assess the effects of re-wetting measures. There are attempts to obtain maps of water table depth at large scales (e.g. national or continental) by using process-based hydrological model concepts. However, major problem of the process-based approach is the representation of the water management (ditches, tile drains, pumping and weir management), which is at the best known spatially just for the ditch patterns. Thus, this approach is hardly applicable to the diversely-drained and -used organic soils in central Europe. Here, we present an alternative, data-driven approach for upscaling annual mean and dynamics of water table depth in organic soils. Groundwater level data of a unique dataset from about 60 peatlands, 1100 dipwells and around 8000 annual data sets, is the basis of this approach. Time series were used to calculate long-term annual means, average annual amplitudes and ponding durations. In case of continuous observations, shape parameters of the annual frequency distribution of water table depths were calculated. For each well, numerous site characteristics were collected as possible explanatory variables. This collection was restricted to nationally-available data. For each dipwell, land use is taken from official land use maps (German database ATKIS), and the soil type from the national geological map (1:200.000). In case of reliable site information, maps were corrected accordingly. Additionally, from these maps, topological indicators such as the ditch distance and density, the distance to the edge of the peatland and the peatland area within different buffers were calculated. Meteorological data (precipitation, potential

  6. Altitude of water table, surficial aquifer, Palm Beach County, Florida, April 24-26, 1984

    Science.gov (United States)

    Miller, Wesley L.

    1985-01-01

    Water levels in Palm Beach County, Florida, were measured in April 1984 to determine the altitude of the water table in the surficial aquifer. A total of 104 wells and 50 surface-water measurement sites were used to contour the altitude of the water table at 2 and 4-foot intervals. The water-level measurements made in April represent low-water levels near the end of south Florida 's dry season. Contours of the water table at this time ranged from 22 feet above sea level in the north-central part of the county to 2 feet near the coast. (USGS)

  7. FIRST NEW SOLAR MODELS WITH OPAS OPACITY TABLES

    Energy Technology Data Exchange (ETDEWEB)

    Le Pennec, M.; Turck-Chièze, S.; Salmon, S. [CEA/IRFU/Service d’Astrophysique, CE Saclay, F-91191 Gif sur Yvette (France); Blancard, C.; Cossé, P.; Faussurier, G.; Mondet, G. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2015-11-10

    Stellar seismology appears more and more as a powerful tool for a better determination of the fundamental properties of solar-type stars. However, the particular case of the Sun is still challenging. For about a decade now, the helioseismic sound-speed determination has continued to disagree with the standard solar model (SSM) prediction, questioning the reliability of this model. One of the sources of uncertainty could be in the treatment of the transport of radiation from the solar core to the surface. In this Letter, we use the new OPAS opacity tables, recently available for solar modeling, to address this issue. We discuss first the peculiarities of these tables, then we quantify their impact on the solar sound-speed and density profiles using the reduced OPAS tables taken on the grids of the OPAL ones. We use the two evolution codes, Modules for Experiments in Stellar Astrophysics and Code Liégeois d’Evolution Stellaire, that led to similar conclusions in the solar radiative zone. In comparison to commonly used OPAL opacity tables, the new solar models are computed for the most recent photospheric composition with OPAS tables and present improvements to the location of the base of the convective zone and to the description of the solar radiative zone in comparison to the helioseismic observations, even if the differences in the Rosseland mean opacity do not exceed 6%. We finally carry out a comparison to a solar model computed with the OP opacity tables.

  8. 花管与潜水面相交下的冲击试验模型研究%STUDY OF MODEL OF SLUG TESTS PERFORMED IN WELLS WHEN WELLS SCREENED ACROSS WATER TABLE

    Institute of Scientific and Technical Information of China (English)

    高彬; 陈建生; 陈亮; 季纯波

    2013-01-01

    For the slug tests performed in wells screened across the water table in phreatic aquifer,the water injects into the wells through the upper and lower parts of the water table. By calculating the amount of the water flowed away from the lower part of the water table using the technique of tracer test with the concentration of solute,a new model of slug test in phreatic aquifer is built up;and the analytical solution of the new model is given. It′s different from the traditional ways to solve this problem,which usually do it by changing some coefficients to correct the radius of the wells. To demonstrate the correctness of this theory,a series of slug tests are conducfed in a fully penetrating well in the Jiangxiong Reservoir in Tibet. And then the hydraulic conductivity of the formation is calculated using the method. By comparing the result of this value to the calculating results of Bouwer-Rice slug,the results show that the proposed model can truly reflect the permeability characteristics of the formation. By analyzing the standard recovery curve of the slug test,it shows that curve can truly reflect the permeability characteristics of the aquifer when the curve decreases in a slower rate.%针对潜水井中的冲击试验,在花管与潜水面相交的情况下,由于注入井中的水分潜水面上、下两个部分流入含水层中,造成模型由线性变成非线性的问题,建立新的潜水井中的冲击试验计算模型,给出模型的解析解,并运用溶质浓度示踪技术,算出从潜水面以下部分流走的的水量,最终得到含水层渗透系数。而这与传统研究中,仅通过对测井的有效半径进行修正,来解决这一问题的方法不同。以西藏江雄水库库区一潜水完整井为例,进行现场试验,运用建立的模型,计算出含水层的渗透系数,并将其与Bouwer-Rice潜水井冲击试验模型的计算结果、以及抽水试验的结果进行对比,试验结果表

  9. Diurnal cycles in water quality across the periodic table

    Science.gov (United States)

    Kirchner, James

    2014-05-01

    Diurnal cycles in water quality can provide important clues to the processes that regulate aquatic chemistry, but they often are masked by longer-term, larger-amplitude variability, making their detection and quantification difficult. Here I outline methods that can detect diurnal cycles even when they are massively obscured by statistically ill-behaved noise. I demonstrate these methods using high-frequency water quality data from the Plylimon catchment in mid-Wales (Neal et al., 2013; Kirchner and Neal, 2013). Several aspects combine to make the Plynlimon data set unique worldwide. Collected at 7-hour intervals, the Plynlimon data set is much more densely sampled than typical long-term weekly or monthly water quality data. This 7-hour sampling was also continued for two years, much longer than typical intensive sampling campaigns, and the resulting time series encompass a wide range of climatic and hydrological conditions. Furthermore, each sample was analyzed for a wide range of solutes with diverse sources in the natural environment. However, the 7-hour sampling frequency is both coarse and irregular in comparison to diurnal cycles, making their detection and quantification difficult. Nonetheless, the methods outlined here enable detection of statistically significant diurnal cycles in over 30 solutes at Plynlimon, including alkali metals (Li, Na, K, Rb, and Cs), alkaline earths (Be, Mg, Ca, Sr, and Ba), transition metals (Al, Ti, Mn, Fe, Co, Ni, Zn, Mo, Cd, and Pb), nonmetals (B, NO3, Si, As, and Se), lanthanides and actinides (La, Ce, Pr, and U), as well as total dissolved nitrogen (TDN), dissolved organic carbon (DOC), Gran alkalinity, pH, and electrical conductivity. These solutes span every row of the periodic table, and more than six orders of magnitude in concentration. Many of these diurnal cycles are subtle, representing only a few percent, at most, of the total variance in the concentration time series. Nonetheless they are diagnostically useful

  10. Generating Lookup Tables from the AE9/AP9 Models

    Science.gov (United States)

    2015-06-16

    NUMBER 11 5e. TASK NUMBER na 5f. WORK UNIT NUMBER na 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) The Aerospace Corporation 2310 E. El...electrons using SOAP and a static 3D table containing data generated from the AE9/AP9 model. ........................................................ 2...used to construct a 3D data table that could be read by the Satellite Orbit Analysis Program ( SOAP ) [2], which is a program developed and maintained

  11. Numerical analysis of a three-phase system with a fluctuating water table

    Energy Technology Data Exchange (ETDEWEB)

    White, M.D.; Lenhard, R.J.

    1993-03-01

    Numerical simulations are presented of a one-dimensional, multiphase flow system that involves the redistribution of aqueous-phase liquids and nonaqueous-phase liquids (NAPLs) by a fluctuating water table. The numerical analyses were completed using an integrated-volume, finite-difference-based solution scheme of the governing multiphase conservation equations and constitutive theory. Conservation equations were solved for two components water and oil, with the assumption of a passive gas-phase. Nonlinearities introduced into the governing conservation equations through the constitutive theory were handled with a multivariable Newton-Raphson iterative scheme. The functional relationships between the phase relative permeability, the phase saturation, and phase pressures in porous media were described with a general theoretical model that includes the effects of air and oil occlusion during imbibition. Parameters required for the theoretical model were defined for two-phase systems (e.g., air- water, air-oil, and oil-water). The theoretical model assumes that wettability decreases in the following order: water, oil, air. Results from the numerical simulations are compared against measurements taken from a previous multiphase flow experiment. The experiment involved subjecting an initially water-drained, three-phase system (i.e., air-oil-water), to a fluctuating water table. The experimental objective was to quantify the entrapment of air and NAPL by phases of greater wettability under dynamic conditions. Comparison of numerical and experimental results were made for two ratios of imbibition to drainage characteristic, curve-shape parameters and two models for relative permeability in two-phase systems. A description of the numerical methods used to solve the governing conservation and constitutive equations for multiphase hysteretic conditions is given.

  12. Spring 1961 water table of California's Central Valley (from Williamson and others, 1989)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset defines the spring 1961 water-table altitude for the California's Central Valley. It was used to initiate the water-level altitudes for the...

  13. Effect of the spatial distribution of physical aquifer properties on water table depth and stream discharge in a headwater catchment

    Directory of Open Access Journals (Sweden)

    C. Gascuel-Odoux

    2009-11-01

    Full Text Available Water table depth and its dynamics is often poorly predicted upslope despite they control both water transit time within the catchment and solute fluxes at the catchment outlet. The paper analyses how relaxing the assumption of lateral homogeneity of physical properties can improve simulations of water table depth and dynamics. Four different spatial models relating of saturated hydraulic conductivity to topography have been tested: a simple linear relationship, a linear relationship with two topographic indexes, two domains with a transitional area. The Hill-Vi model has been modified to test these hypotheses. The studied catchment (Kervidy-Naizin, western France is underlain by schist crystalline bedrock. A shallow and perennial groundwater highly reactive to rainfall events mainly develops in the weathered saprolite layer. The results indicate that 1 discharge and the water table in the riparian zone are similarly predicted with the four models, 2 distinguishing two domains constitutes the best model and slightly improves prediction of the water table upslope, and 3 including spatial variations in the other parameters such as porosity or rate of hydraulic conductivity decrease with depth does not improve the results. These results underline the necessity of better investigation of upslope areas in hillslope hydrology.

  14. Measuring the Change in Water Table with Gravity Methods - a Controlled Experiment

    DEFF Research Database (Denmark)

    Lund, S; Christiansen, Lars; Andersen, O. B.;

    2009-01-01

    Gravity changes linearly with the change in soil water content. With the GRACE satellite mission the interest for ground-based gravity methods in hydrology has gained new attention. Time-lapse gravity data have the potential to constrain hydrological model parameters in a calibration scheme...... in water content, a controlled experiment was set up in 30 m by 20 m basin. The water table was lowered 0.69 m within 1½ hours and the corresponding gravity signal measured using two different approaches: a time series measurements at one location and a gravity network measurement including four points....... Both where in agreement with the calculated maximum theoretical gravity change of 27*10^-8 m/s^2. Uncertainties on the change in gravity in the network measurements where 4*10^-8 m/s^2 (one standard deviation). This corresponds to an infinite horizontal slab of water with a thickness of 0.1 m. The time...

  15. Unraveling uncertainties of water table slope assessment with DGPS in lowland floodplain wetlands.

    Science.gov (United States)

    Mirosław-Świątek, Dorota; Michałowski, Robert; Szporak-Wasilewska, Sylwia; Ignar, Stefan; Grygoruk, Mateusz

    2016-11-01

    In our study, we analyzed the combined standard uncertainty of water table slope assessment done using differential global positioning system (DGPS)-based measurements of water table elevation and distances between measurement locations. We compared and discussed uncertainties in water table slope assessments done in various hypothetical environments of lowland floodplains (water table slopes typically ranged from 1.25 · 10(-4) to 1 · 10(-3)). Our analyses referred to elevation measurements done with the static GPS and DGPS real-time kinematic (RTK) approaches, which are currently among the most frequently used elevation measurement techniques worldwide. Calculations of the combined standard uncertainty of water table slope allowed us to conclude that the DGPS-RTK approach used in water table slope assessment can result in assessment errors as high as 50 % at short (<200 m) distances. Acceptable water table slope measurement errors (lower than 5 %) occur at distances longer than 11,320 m in the case of DGPS-RTK measurements, while, in the case of static GPS measurements, acceptable measurement errors at the same level occur at distances as low as 1350 m. Errors in water table slope assessment as high as 50 % occur at distances of 1130 m and 140 m for DGPS-RTK and static GPS measurements, respectively. We conclude that, although the DGPS-RTK methodology-due to its ease of use and time-saving capabilities is very often applied to water level measurements in lowland riparian wetlands, the application of the DGPS-RTK methodology for water table slope assessment at distances shorter than a few couples of meters results in very low accuracy (errors greater than 50 %) and should not be used for calculating local slopes in low slope areas such as lowland riparian zones.

  16. Model Checking with Probabilistic Tabled Logic Programming

    CERN Document Server

    Gorlin, Andrey; Smolka, Scott A

    2012-01-01

    We present a formulation of the problem of probabilistic model checking as one of query evaluation over probabilistic logic programs. To the best of our knowledge, our formulation is the first of its kind, and it covers a rich class of probabilistic models and probabilistic temporal logics. The inference algorithms of existing probabilistic logic-programming systems are well defined only for queries with a finite number of explanations. This restriction prohibits the encoding of probabilistic model checkers, where explanations correspond to executions of the system being model checked. To overcome this restriction, we propose a more general inference algorithm that uses finite generative structures (similar to automata) to represent families of explanations. The inference algorithm computes the probability of a possibly infinite set of explanations directly from the finite generative structure. We have implemented our inference algorithm in XSB Prolog, and use this implementation to encode probabilistic model...

  17. Regional water table (2014) in the Mojave River and Morongo Groundwater Basins, southwestern Mojave Desert, California

    Science.gov (United States)

    Teague, Nick F.; Stamos, Christina L.; House, Sally F.; Clark, Dennis A.

    2016-06-28

    2014 Water TableData for static water levels measured in about 610 wells during March–April 2014 by the U.S. Geological Survey (USGS), the Mojave Water Agency (MWA), and other local water districts were compiled to construct this regional water-table map. This map shows the elevation of the water table and general direction of groundwater movement in and around the Mojave River and Morongo groundwater basins. Water levels recorded by the USGS and MWA staff were measured and compiled according to the procedures described in the Groundwater Technical Procedures of the U.S. Geological Survey (Cunningham and Schalk, 2011). Water-level data submitted by cooperating local water districts were collected by using procedures established by the corresponding agency and were compiled according to the procedures described in the Groundwater Technical Procedures of the U.S. Geological Survey (Cunningham and Schalk, 2011). All data were compared to historical data for qualityassurance purposes. Water-level contours from the 2012 water-level map (Teague and others, 2014) were used as a guide to interpret and shape the 2014 water-level contours in areas where 2014 water-level data were not available; these contours are shown as dashed (approximate) on this water-table map. Water-level data and contours are shown for the Warren subbasin in the Morongo groundwater basin in greater detail on inset A.The water table is the surface at which the fluid pressure in the pores of a porous medium is exactly atmospheric (Freeze and Cherry, 1979). The water table is defined by the level of the water surface in wells that just penetrate the top of the water body (Lohman, 1972). The water-level measurements used for the water-level contour maps are from wells that have more than one perforated interval in the saturated zone of the groundwater basins. Although these wells can have different perforated zones, the measured water levels from the zones were within about 10 feet (ft) and, therefore

  18. Bilinear modulation models for seasonal tables of counts

    NARCIS (Netherlands)

    B.D. Marx (Brian); P.H.C. Eilers (Paul); J. Gampe (Jutta); R. Rau (Roland)

    2010-01-01

    textabstractWe propose generalized linear models for time or age-time tables of seasonal counts, with the goal of better understanding seasonal patterns in the data. The linear predictor contains a smooth component for the trend and the product of a smooth component (the modulation) and a periodic t

  19. Water table fluctuations and soil biogeochemistry: An experimental approach using an automated soil column system

    Science.gov (United States)

    Rezanezhad, F.; Couture, R.-M.; Kovac, R.; O'Connell, D.; Van Cappellen, P.

    2014-02-01

    Water table fluctuations significantly affect the biological and geochemical functioning of soils. Here, we introduce an automated soil column system in which the water table regime is imposed using a computer-controlled, multi-channel pump connected to a hydrostatic equilibrium reservoir and a water storage reservoir. The potential of this new system is illustrated by comparing results from two columns filled with 45 cm of the same homogenized riparian soil. In one soil column the water table remained constant at -20 cm below the soil surface, while in the other the water table oscillated between the soil surface and the bottom of the column, at a rate of 4.8 cm d-1. The experiment ran for 75 days at room temperature (25 ± 2 °C). Micro-sensors installed at -10 and -30 cm below the soil surface in the stable water table column recorded constant redox potentials on the order of 600 and -200 mV, respectively. In the fluctuating water table column, redox potentials at the same depths oscillated between oxidizing (∼700 mV) and reducing (∼-100 mV) conditions. Pore waters collected periodically and solid-phase analyses on core material obtained at the end of the experiment highlighted striking geochemical differences between the two columns, especially in the time series and depth distributions of Fe, Mn, K, P and S. Soil CO2 emissions derived from headspace gas analysis exhibited periodic variations in the fluctuating water table column, with peak values during water table drawdown. Transient redox conditions caused by the water table fluctuations enhanced microbial oxidation of soil organic matter, resulting in a pronounced depletion of particulate organic carbon in the midsection of the fluctuating water table column. Denaturing Gradient Gel Electrophoresis (DGGE) revealed the onset of differentiation of the bacterial communities in the upper (oxidizing) and lower (reducing) soil sections, although no systematic differences in microbial community structure

  20. Evaluating the value of ENVISAT ASAR Data for the mapping and monitoring of peatland water table depths

    Science.gov (United States)

    Bechtold, Michel; Schlaffer, Stefan

    2015-04-01

    summer mean water table depth. Using the boosted regression tree model of Bechtold et al., we evaluate whether the ASAR data can improve prediction accuracy and/or replace parts of ancillary data that is often not available in other countries. In the temporal domain primary results often show a better dependency between backscatter and water table depths compared to the spatial domain. For a variety of vegetation covers the temporal monitoring potential of ASAR data is evaluated at the level of annual water table depth statistics. Bechtold, M., Tiemeyer, B., Laggner, A., Leppelt, T., Frahm, E., and Belting, S., 2014. Large-scale regionalization of water table depth in peatlands optimized for greenhouse gas emission upscaling, Hydrol. Earth Syst. Sci., 18, 3319-3339. Dettmann, U., Bechtold, M., Frahm, E., Tiemeyer, B., 2014. On the applicability of unimodal and bimodal van Genuchten-Mualem based models to peat and other organic soils under evaporation conditions. Journal of Hydrology, 515, 103-115. Reschke, J., Bartsch, A., Schlaffer, S., Schepaschenko, D., 2012. Capability of C-Band SAR for Operational Wetland Monitoring at High Latitudes. Remote Sens. 4, 2923-2943.

  1. Contribution of peptides and polyphenols from olive water to acrylamide formation in sterilized table olives

    OpenAIRE

    Casado, Francisco Javier; Montaño, Alfredo; Carle, Reinhold

    2014-01-01

    To confirm the role of peptides as principal precursors of acrylamide formation in sterilized table olives, peptides from olive water were fractionated. After their partial fractionation by solid phase extraction (SPE) and ultrafiltration (

  2. Diffusive-dispersive mass transfer in the capillary fringe: Impact of water table fluctuations and heterogeneities

    DEFF Research Database (Denmark)

    Grathwohl, Peter; Haberer, Cristina; Ye, Yu;

    Diffusive–dispersive mass transfer in the capillary fringe is important for many groundwater quality issues such as transfer of volatile compounds into (and out of) the groundwater, the supply of oxygen for aerobic degradation of hydrocarbons as well as for precipitation of minerals (e.g. iron...... hydroxides). 2D-laboratory scale experiments were used to investigate the transfer of oxygen into groundwater under non-reactive and reactive conditions, at steady state and with water table fluctuations. Results show that transfer of oxygen is limited by transverse dispersion in the capillary fringe...... and the dispersion coefficients are the same as below the water table. Water table fluctuations cause temporarily increased fluxes of oxygen into groundwater during draining conditions and entrapped air after water table rise. High-permeability inclusions in the capillary fringe enhance mass transfer of oxygen...

  3. Testing peatland water-table depth transfer functions using high-resolution hydrological monitoring data

    Science.gov (United States)

    Swindles, Graeme T.; Holden, Joseph; Raby, Cassandra L.; Turner, T. Edward; Blundell, Antony; Charman, Dan J.; Menberu, Meseret Walle; Kløve, Bjørn

    2015-07-01

    Transfer functions are now commonly used to reconstruct past environmental variability from palaeoecological data. However, such approaches need to be critically appraised. Testate amoeba-based transfer functions are an established method for the quantitative reconstruction of past water-table variations in peatlands, and have been applied to research questions in palaeoclimatology, peatland ecohydrology and archaeology. We analysed automatically-logged peatland water-table data from dipwells located in England, Wales and Finland and a suite of three year, one year and summer water-table statistics were calculated from each location. Surface moss samples were extracted from beside each dipwell and the testate amoebae community composition was determined. Two published transfer functions were applied to the testate-amoeba data for prediction of water-table depth (England and Europe). Our results show that estimated water-table depths based on the testate amoeba community reflect directional changes, but that they are poor representations of the real mean or median water-table magnitudes for the study sites. We suggest that although testate amoeba-based reconstructions can be used to identify past shifts in peat hydrology, they cannot currently be used to establish precise hydrological baselines such as those needed to inform management and restoration of peatlands. One approach to avoid confusion with contemporary water-table determinations is to use residuals or standardised values for peatland water-table reconstructions. We contend that our test of transfer functions against independent instrumental data sets may be more powerful than relying on statistical testing alone.

  4. Water table fluctuation and its effects on vegetation in a semiarid environment

    Directory of Open Access Journals (Sweden)

    L. Duan

    2011-04-01

    Full Text Available A good understanding of water table fluctuation effects on vegetation is crucial for sustaining fragile hydrology and ecology of semiarid areas such as the Horqin Sandy Land (HSL in northern China, but such understanding is not well documented in literature. The objectives of this study were to examine spatio-temporal variations of water table and their effects on vegetation in a semiarid environment. A 9.71 km2 area within the HSL was chosen and well-instrumented to continuously measure hydrometeorologic parameters (e.g., water table. The area comprises of meadow lands and sandy dunes as well as transitional zones in between. In addition to those measured data, this study also used Landsat TM and MODIS imageries and meteorological data at a station near the study area. The spatio-temporal variations were examined using visual plots and contour maps, while the effects on vegetation were determined by overlaying a water table depth map with a vegetation index map derived from the MODIS imageries. The results indicated that water table was mainly dependent on local topography, localized geological settings, and human activities (e.g., reclamation. At annual and monthly scales, water table was mainly a function of precipitation and potential evapotranspiration. A region within the study area where depth to water table was smaller tended to have better (i.e., more dense and productive vegetation cover. Further, the results revealed that water table fluctuation was more sensitive for vegetations in the meadow lands than in the transitional zones, but it was least sensitive for vegetations in the sandy dunes.

  5. Water table fluctuation and its effects on vegetation in a semiarid environment

    Science.gov (United States)

    Duan, L.; Liu, T.; Wang, X.; Luo, Y.; Wang, W.; Liu, X.

    2011-04-01

    A good understanding of water table fluctuation effects on vegetation is crucial for sustaining fragile hydrology and ecology of semiarid areas such as the Horqin Sandy Land (HSL) in northern China, but such understanding is not well documented in literature. The objectives of this study were to examine spatio-temporal variations of water table and their effects on vegetation in a semiarid environment. A 9.71 km2 area within the HSL was chosen and well-instrumented to continuously measure hydrometeorologic parameters (e.g., water table). The area comprises of meadow lands and sandy dunes as well as transitional zones in between. In addition to those measured data, this study also used Landsat TM and MODIS imageries and meteorological data at a station near the study area. The spatio-temporal variations were examined using visual plots and contour maps, while the effects on vegetation were determined by overlaying a water table depth map with a vegetation index map derived from the MODIS imageries. The results indicated that water table was mainly dependent on local topography, localized geological settings, and human activities (e.g., reclamation). At annual and monthly scales, water table was mainly a function of precipitation and potential evapotranspiration. A region within the study area where depth to water table was smaller tended to have better (i.e., more dense and productive) vegetation cover. Further, the results revealed that water table fluctuation was more sensitive for vegetations in the meadow lands than in the transitional zones, but it was least sensitive for vegetations in the sandy dunes.

  6. Water table tests of proposed heat transfer tunnels for small turbine vanes

    Science.gov (United States)

    Meitner, P. L.

    1974-01-01

    Water-table flow tests were conducted for proposed heat-transfer tunnels which were designed to provide uniform flow into their respective test sections of a single core engine turbine vane and a full annular ring of helicopter turbine vanes. Water-table tests were also performed for the single-vane test section of the core engine tunnel. The flow in the heat-transfer tunnels was shown to be acceptable.

  7. Geostatistical investigation into the temporal evolution of spatial structure in a shallow water table

    Directory of Open Access Journals (Sweden)

    S. W. Lyon

    2006-01-01

    Full Text Available Shallow water tables near-streams often lead to saturated, overland flow generating areas in catchments in humid climates. While these saturated areas are assumed to be principal biogeochemical hot-spots and important for issues such as non-point pollution sources, the spatial and temporal behavior of shallow water tables, and associated saturated areas, is not completely understood. This study demonstrates how geostatistical methods can be used to characterize the spatial and temporal variation of the shallow water table for the near-stream region. Event-based and seasonal changes in the spatial structure of the shallow water table, which influences the spatial pattern of surface saturation and related runoff generation, can be identified and used in conjunction to characterize the hydrology of an area. This is accomplished through semivariogram analysis and indicator kriging to produce maps combining soft data (i.e., proxy information to the variable of interest representing general shallow water table patterns with hard data (i.e., actual measurements that represent variation in the spatial structure of the shallow water table per rainfall event. The area used was a hillslope in the Catskill Mountains region of New York State. The shallow water table was monitored for a 120 m×180 m near-stream region at 44 sampling locations on 15-min intervals. Outflow of the area was measured at the same time interval. These data were analyzed at a short time interval (15 min and at a long time interval (months to characterize the changes in the hydrologic behavior of the hillslope. Indicator semivariograms based on binary-transformed ground water table data (i.e., 1 if exceeding the time-variable median depth to water table and 0 if not were created for both short and long time intervals. For the short time interval, the indicator semivariograms showed a high degree of spatial structure in the shallow water table for the spring, with increased range

  8. Environmental Monitoring, Water Quality - MO 2014 Water Quality Standards - Table H Stream Classifications and Use Designations (SHP)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This feature class contains Missouri's use designations for streams listed in Table H of the Water Quality Standards rule published in the Missouri Code of State...

  9. Analysis of uncertainties, associated to the calculating hypothesis, in discharge tables for high flows estimating, based on mathematics models for calculating water surface profiles fore steady gradually varied flow; Analisis de las incertidumbres, asociadas a las hipotesis de calculo, en la estimacion de curvas de gasto para crcidas, basada en el empleo de modelo matematico de calculo hidraulico en regimen permanente

    Energy Technology Data Exchange (ETDEWEB)

    Aldana Valverde, A. L.; Gonzalez Rodriguez, J. C.

    1999-08-01

    In this paper are analyzed some of the most important factors which can influence on the results of calculating water surface profiles for steady gradually varied flow. In this case, the objective of this kind of modeling, has been the estimation of discharges tables for high flows of river station gages connected to the hydrologic automatic information system (SAIH) of the Confederacion Hidrografica del Sur de Espana, system named red Hidrosur. (Author) 3 refs

  10. Modeling the treatment table; Modelado de la mesa de tratamiento

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz Arrebola, S.; Vilches Pacheco, M.; Manchado de Sola, F.; Guirado Llorente, D.

    2011-07-01

    This paper presents an analytical model to characterize the attenuation caused by the treatment table of a linear accelerator recently established. The discrepancy for certain angles of the arm between the attenuation value indicated by the manufacturer and the actually observed is the origin of this work. Our goal was to obtain an analytical attenuation function can be implemented in a simple way, in any planning system SP, through the modulation of the incident flow matrix.

  11. Treatment of table olive washing water using trickling filters, constructed wetlands and electrooxidation.

    Science.gov (United States)

    Tatoulis, Triantafyllos; Stefanakis, Alexandros; Frontistis, Zacharias; Akratos, Christos S; Tekerlekopoulou, Athanasia G; Mantzavinos, Dionissios; Vayenas, Dimitrios V

    2017-01-01

    The production of table olives is a significant economic activity in Mediterranean countries. Table olive processing generates large volumes of rinsing water that are characterized by high organic matter and phenol contents. Due to these characteristics, a combination of more than one technology is imperative to ensure efficient treatment with low operational cost. Previously, biological filters were combined with electrooxidation to treat table olive washing water. Although this combination was successful in reducing pollutant loads, its cost could be further reduced. Constructed wetlands could be an eligible treatment method for integrated table olive washing water treatment as they have proved tolerant to high organic matter and phenol loads. Two pilot-scale horizontal subsurface constructed wetlands, one planted and one unplanted, were combined with a biological filter and electrooxidation over a boron-doped diamond anode to treat table olive washing water. In the biological filter inlet, chemical oxygen demand (COD) concentrations ranged from 5500 to 15,000 mg/L, while mean COD influent concentration in the constructed wetlands was 2800 mg/L. The wetlands proved to be an efficient intermediate treatment stage, since COD removal levels for the planted unit reached 99 % (mean 70 %), while the unplanted unit presented removal rates of around 65 %. Moreover, the concentration of phenols in the effluent was typically below 100 mg/L. The integrated trickling filter-constructed wetland-electrooxidation treatment system examined here could mineralize and decolorize table olive washing water and fully remove its phenolic content.

  12. Exploring Soil Layers and Water Tables with Ground-Penetrating Radar

    Institute of Scientific and Technical Information of China (English)

    K. ROTH; U. WOLLSCHLAGER; CHENG Zhu-Hua; ZHANG Jia-Bao

    2004-01-01

    Ground-penetrating radar (GPR) has been used predominantly for environments with low electrical conductivity like freshwater aquifers, glaciers, or dry sandy soils. The objective of the present study was to explore its application for mapping in subsurface agricultural soils to a depth of several meters. For a loamy sand and a clayey site on the North China Plain, clay inclusions in the sand were detected; the thickness, inclination, and continuity of the confining clay and silt layers was assessed; and a local water table was mapped. Direct sampling (soil coring and profiling) in the top meter and independent measurement of the water table were utilized to confirm the findings. Also, effective estimates of the dielectric number for the site with the dielectric number of moist clayey soils depending strongly on frequency were obtained. Thus, important properties of soils, like the arrangement and type of layers and in particular their continuity and inclination, could be explored with moderate efforts for rather large areas to help find optimal locations for the time-consuming and expensive measurements which would be necessary to detail a model of the subsurface.

  13. The complex relationships between methane emissions and water table at an ombrotrophic bog

    Science.gov (United States)

    Humphreys, Elyn; Roulet, Nigel; Moore, Tim

    2017-04-01

    Broad spatial and temporal variations in methane emissions from peatlands have been related to many variables including water table position, temperature and vegetation characteristics and functioning. In general, wetter peatlands tend to have greater methane emissions. However, over shorter periods of time and space, the relationship between water table and methane emissions can reverse, show hysteresis or be absent entirely. These relationships are investigated at the Mer Bleue Bog, a temperate ombrotrophic bog near Ottawa, Canada. Six years of concurrent growing season eddy covariance and automated chamber fluxes reveal the expected broad patterns. During the wettest growing season, the water table remained within 40 cm of the bog's hummock surfaces. Methane emissions were upwards of 20 to 45 mg C m-2 d-1 and exceeded the emission rates from two drier growing seasons which saw periods where the water table dropped to nearly 80 cm below the hummock surface. In those periods, methane emission rates declined to about 5 mg C m-2 d-1 or less. Lawn plots with aerenchymatous Eriophorum vegetation and high water tables had greatest emissions (exceeding 200 mg C m-2 d-1) compared to hummock plots vegetated by ericaceous shrubs, which had emissions rates similar to those measured by eddy covariance. However, within a growing season, hysteresis and inverse relationships between water table and methane emissions were observed at both ecosystem and chamber plot scales. These included periods between rainfall events where methane emissions increased while the water table deepened. The potential roles of methane production, consumption, storage and transport processes on these patterns will be discussed.

  14. Remediation of an Organic Fluid Present Below the Water Table by Steam Injection Above

    Science.gov (United States)

    Gudbjerg, J.; Jensen, K. H.; Sonnenborg, T. O.

    2001-12-01

    Injection of steam in the subsurface has been utilized to remediate contaminated sites where nonaqeuous phase liquid (NAPL) was present both above and below the water table. Steam injection is efficient because the vapor pressure of contaminants increase dramatically with temperature. Futhermore, since two immiscible liquids will boil when the sum of their vapor pressures is equal to the surrounding pressure all NAPLs will start to boil below the boiling point of water. This may be a dominant mechanism for the mass transfer of NAPL into the steam zone. In many cases a steady-state steam zone will be present above a saturated zone containing NAPL, which then will be heated by conduction. At a certain temperature boiling will occur and due to bouyancy gas will be transported from the saturated zone into the steam zone. This mass transfer mechanism is orders of magnitude faster than diffusionevaporation. Two-dimensional experiments in a sand box with the interior dimensions 122 \\times 58 \\times 8.5 cm were carried out to investigate this mechanism. The sand box was packed with a low permeable bottom layer and a high permeable top layer. TCE was injected at the top of the low permeable layer, which prevented it from further downward migration. The water table was located in the high permeable layer above the contaminant. Steam was injected in the left hand side of the sand box and effluent gasses were extracted at the right hand side. A steady-state steam zone formed in the top of the high permeable layer and the saturated zone below was only heated by conduction. When the temperature in the contaminated area reached approximately 74 oC boiling of TCE and water occured and the vapors were transported up in the unsaturated steam zone. This could be registered from the outflow of steam where separate phase TCE appeared in the condenser. The experiment was modeled using the numerical code T2VOC, which simulates multidimensional, non-isothermal, multiphase flow and

  15. Overriding control of methane flux temporal variability by water table dynamics in a Southern Hemisphere, raised bog

    Science.gov (United States)

    Goodrich, J. P.; Campbell, D. I.; Roulet, N. T.; Clearwater, M. J.; Schipper, L. A.

    2015-05-01

    There are still large uncertainties in peatland methane flux dynamics and insufficient understanding of how biogeochemical processes scale to ecosystems. New Zealand bogs differ from Northern Hemisphere ombrotrophic systems in climatic setting, hydrology, and dominant vegetation, offering an opportunity to evaluate our knowledge of peatland methane biogeochemistry gained primarily from northern bogs and fens. We report eddy covariance methane fluxes from a raised bog in New Zealand over 2.5 years. Annual total methane flux in 2012 was 29.1 g CH4 m-2 yr-1, whereas during a year with a severe drought (2013) it was 20.6 g CH4 m-2 yr-1, both high compared to Northern Hemisphere bogs and fens. Drier conditions led to a decrease in fluxes from ~100 mg CH4 m-2 d-1 to ~20 mg CH4 m-2 d-1, and subsequent slow recovery of flux after postdrought water table rise. Water table depth regulated the temperature sensitivity of methane fluxes, and this sensitivity was greatest when the water table was within 100 mm of the surface, corresponding to the shallow rooting zone of the dominant vegetation. A correlation between daytime CO2 uptake and methane fluxes emerged during times with shallow water tables, suggesting that controls on methane production were critical in determining fluxes, more so than oxidation. Water table recession through this shallow zone led to increasing methane fluxes, whereas changes in temperature during these periods were not correlated. Models of methane fluxes should consider drought-induced lags in seasonal flux recovery that depend on drought characteristics and location of the critical zone for methane production.

  16. Contribution of vegetation and water table on isoprene emission from boreal peatland microcosms

    DEFF Research Database (Denmark)

    Tiiva, Päivi; Faubert, Patrick; Räty, Sanna;

    2009-01-01

    Boreal peatlands are substantial sources of isoprene, a reactive hydrocarbon. However, it is not known how much mosses, vascular plants and peat each contribute to isoprene emission from peatlands. Furthermore, there is no information on the effects of declining water table depth on isoprene emis....... In conclusion, isoprene emissions from peatlands will decrease, but the proportion of assimilated carbon lost as isoprene will increase, if the naturally high water table declines under the changing climate....... emission in these naturally wet ecosystems, although water table is predicted to decline due to climate warming. We studied the relative contribution of mosses vs. vascular plants to isoprene emission in boreal peatland microcosms in growth chambers by removing either vascular vegetation or both vascular...... hollows with intact vegetation, 45 ± 6 µg m-2 h-1, was decreased by 25% under water table drawdown. However, water table drawdown reduced net ecosystem carbon dioxide (CO2) exchange more dramatically than isoprene emission. Isoprene emission strongly correlated with both CO2 exchange and methane emission...

  17. Study of energy transfer in table-top X-pinch driven by a water line

    Energy Technology Data Exchange (ETDEWEB)

    Beg, F N [Mechanical and Aerospace Department, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA92093-0411 (United States); Zhang, T [Mechanical and Aerospace Department, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA92093-0411 (United States); Fedin, D [Mechanical and Aerospace Department, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA92093-0411 (United States); Beagen, B [Anglo Chinese Junior College, 25 Dover Close East, Singapore 139745 (Singapore); Chua, E [Anglo Chinese Junior College, 25 Dover Close East, Singapore 139745 (Singapore); Lee, J Y [Anglo Chinese Junior College, 25 Dover Close East, Singapore 139745 (Singapore); Rawat, R S [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Lee, P [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

    2007-08-15

    The current passing through X-pinches and the energy transferring from the pulse forming line to the load are modelled using a simple LCR circuit. A comparison of the electrical properties of two table-top X-pinch devices is made. It was found that up to 25% of the stored energy is transferred from the water transmission line to the load in the University of California,San Diego (UCSD) table-top X-pinch before x-ray emission starts. The highest energy transmitted (75%) is found after the current peak. In comparison, only 3% of the energy is transferred to the load in the National Institute of Education (NIE) X-pinch device just after the maximum current peak. The highest energy (25%) transmitted to the plasma occurs long after the current peak. The plasma in both devices is visually and qualitatively similar. However, the UCSD device emits intense x-rays with no x-rays observed in the NIE device. This observation is consistent with the electrical circuit analysis.

  18. Precipitation patterns and moisture fluxes in a sandy, tropical environment with a shallow water table

    Science.gov (United States)

    Minihane, M. R.; Freyberg, D. L.

    2011-08-01

    Identifying the dominant mechanisms controlling recharge in shallow sandy soils in tropical climates has received relatively little attention. Given the expansion of coastal fill using marine sands and the growth of coastal populations throughout the tropics, there is a need to better understand the nature of water balances in these settings. We use time series of field observations at a coastal landfill in Singapore coupled with numerical modeling using the Richards' equation to examine the impact of precipitation patterns on soil moisture dynamics, including percolation past the root zone and recharge, in such an environment. A threshold in total precipitation event depth, much more so than peak precipitation intensity, is the strongest event control on recharge. However, shallow antecedent moisture, and therefore the timing between events along with the seasonal depth to water table, also play significant roles in determining recharge amounts. For example, at our field site, precipitation events of less than 3 mm per event yield little to no direct recharge, but for larger events, moisture content changes below the root zone are linearly correlated to the product of the average antecedent moisture content and the total event precipitation. Therefore, water resources planners need to consider identifying threshold precipitation volumes, along with the multiple time scales that capture variability in event antecedent conditions and storm frequency in assessing the role of recharge in coastal water balances in tropical settings.

  19. Water tables constrain height recovery of willow on Yellowstone's northern range.

    Science.gov (United States)

    Bilyeu, Danielle M; Cooper, David J; Hobbs, N Thompson

    2008-01-01

    Excessive levels of herbivory may disturb ecosystems in ways that persist even when herbivory is moderated. These persistent changes may complicate efforts to restore ecosystems affected by herbivores. Willow (Salix spp.) communities within the northern range in Yellowstone National Park have been eliminated or degraded in many riparian areas by excessive elk (Cervus elaphus L.) browsing. Elk browsing of riparian willows appears to have diminished following the reintroduction of wolves (Canis lupis L.), but it remains uncertain whether reduced herbivory will restore willow communities. The direct effects of elk browsing on willows have been accompanied by indirect effects from the loss of beaver (Castor canadensis Kuhl) activity, including incision of stream channels, erosion of fine sediments, and lower water tables near streams historically dammed by beaver. In areas where these changes have occurred, lowered water tables may suppress willow height even in the absence of elk browsing. We conducted a factorial field experiment to understand willow responses to browsing and to height of water tables. After four years of protection from elk browsing, willows with ambient water tables averaged only 106 cm in height, with negligible height gain in two of three study species during the last year of the experiment. Willows that were protected from browsing and had artificially elevated water tables averaged 147 cm in height and gained 19 cm in the last year of the experiment. In browsed plots, elevated water tables doubled height gain during a period of slightly reduced browsing pressure. We conclude that water availability mediates the rate of willow height gain and may determine whether willows grow tall enough to escape the browse zone of elk and gain resistance to future elk browsing. Consequently, in areas where long-term beaver absence has resulted in incised stream channels and low water tables, a reduction in elk browsing alone may not be sufficient for recovery

  20. A look-up table for trans-critical heat transfer in water-cooled tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zahlan, H.; Tavoularis, S., E-mail: stavros.tavoularis@uottawa.ca; Groeneveld, D.C.

    2015-04-15

    Highlights: • A new look-up table has been created for high subcritical and supercritical heat transfer. • The table is more accurate than previous methods. • The table can be expanded to account for different effects. - Abstract: This article describes the development and validation of a trans-critical heat transfer look-up table for water at high subcritical and supercritical pressures. As a basis for constructing the table, an extensive database of near-critical and supercritical heat transfer measurements was compiled and upgraded by the rejection of unreliable or inappropriate data, the removal of duplicates and outliers and the reduction of data scatter. A large number of available single-phase and supercritical heat transfer correlations were assessed against the database and the most accurate correlations for each heat transfer regime were identified. These correlations were then used to construct a skeleton table, which provides values of the heat transfer coefficient for a matrix of combinations of 11 values of pressure in the range from 19 to 30 MPa, 9 values of mass flux in the range from 100 to 5000 kg/m{sup 2} s, 17 values of bulk enthalpy in the range from 1000 to 3000 kJ/kg, and 8 values of wall superheat in the range from 10 to 500 K. For the construction of the final table, the predictions of correlations were replaced by experimental values, adjusted following established trends to conform to the skeleton table value matrix. Unlike all previous prediction methods, the table applies not only to normal heat transfer conditions but also to conditions with heat transfer deterioration and enhancement, as it includes data obtained under such conditions. The table values were further adjusted so that apparent discontinuities that were not related to physically plausible changes in heat transfer were smoothened out. The predictions of the table were assessed statistically against the experimental database. When compared to predictions of other

  1. Geostatistical investigations for suitable mapping of the water table: the Bordeaux case (France)

    Science.gov (United States)

    Guekie simo, Aubin Thibaut; Marache, Antoine; Lastennet, Roland; Breysse, Denys

    2016-02-01

    Methodologies have been developed to establish realistic water-table maps using geostatistical methods: ordinary kriging (OK), cokriging (CoK), collocated cokriging (CoCoK), and kriging with external drift (KED). In fact, in a hilly terrain, when piezometric data are sparsely distributed over large areas, the water-table maps obtained by these methods provide exact water levels at monitoring wells but fail to represent the groundwater flow system, manifested through an interpolated water table above the topography. A methodology is developed in order to rebuild water-table maps for urban areas at the city scale. The interpolation methodology is presented and applied in a case study where water levels are monitored at a set of 47 points for a part urban domain covering 25.6 km2 close to Bordeaux city, France. To select the best method, a geographic information system was used to visualize surfaces reconstructed with each method. A cross-validation was carried out to evaluate the predictive performances of each kriging method. KED proves to be the most accurate and yields a better description of the local fluctuations induced by the topography (natural occurrence of ridges and valleys).

  2. Large-scale regionalization of water table depth in peatlands optimized for greenhouse gas emission upscaling

    Science.gov (United States)

    Bechtold, M.; Tiemeyer, B.; Laggner, A.; Leppelt, T.; Frahm, E.; Belting, S.

    2014-09-01

    Fluxes of the three main greenhouse gases (GHG) CO2, CH4 and N2O from peat and other soils with high organic carbon contents are strongly controlled by water table depth. Information about the spatial distribution of water level is thus a crucial input parameter when upscaling GHG emissions to large scales. Here, we investigate the potential of statistical modeling for the regionalization of water levels in organic soils when data covers only a small fraction of the peatlands of the final map. Our study area is Germany. Phreatic water level data from 53 peatlands in Germany were compiled in a new data set comprising 1094 dip wells and 7155 years of data. For each dip well, numerous possible predictor variables were determined using nationally available data sources, which included information about land cover, ditch network, protected areas, topography, peatland characteristics and climatic boundary conditions. We applied boosted regression trees to identify dependencies between predictor variables and dip-well-specific long-term annual mean water level (WL) as well as a transformed form (WLt). The latter was obtained by assuming a hypothetical GHG transfer function and is linearly related to GHG emissions. Our results demonstrate that model calibration on WLt is superior. It increases the explained variance of the water level in the sensitive range for GHG emissions and avoids model bias in subsequent GHG upscaling. The final model explained 45% of WLt variance and was built on nine predictor variables that are based on information about land cover, peatland characteristics, drainage network, topography and climatic boundary conditions. Their individual effects on WLt and the observed parameter interactions provide insight into natural and anthropogenic boundary conditions that control water levels in organic soils. Our study also demonstrates that a large fraction of the observed WLt variance cannot be explained by nationally available predictor variables and

  3. Large-scale regionalization of water table depth in peatlands optimized for greenhouse gas emission upscaling

    Directory of Open Access Journals (Sweden)

    M. Bechtold

    2014-04-01

    Full Text Available Fluxes of the three main greenhouse gases (GHG CO2, CH4 and N2O from peat and other organic soils are strongly controlled by water table depth. Information about the spatial distribution of water level is thus a crucial input parameter when upscaling GHG emissions to large scales. Here, we investigate the potential of statistical modeling for the regionalization of water levels in organic soils when data covers only a small fraction of the peatlands of the final map. Our study area is Germany. Phreatic water level data from 53 peatlands in Germany were compiled in a new dataset comprising 1094 dip wells and 7155 years of data. For each dip well, numerous possible predictor variables were determined using nationally available data sources, which included information about land cover, ditch network, protected areas, topography, peatland characteristics and climatic boundary conditions. We applied boosted regression trees to identify dependencies between predictor variables and dip well specific long-term annual mean water level (WL as well as a transformed form of it (WLt. The latter was obtained by assuming a hypothetical GHG transfer function and is linearly related to GHG emissions. Our results demonstrate that model calibration on WLt is superior. It increases the explained variance of the water level in the sensitive range for GHG emissions and avoids model bias in subsequent GHG upscaling. The final model explained 45% of WLt variance and was built on nine predictor variables that are based on information about land cover, peatland characteristics, drainage network, topography and climatic boundary conditions. Their individual effects on WLt and the observed parameter interactions provide insights into natural and anthropogenic boundary conditions that control water levels in organic soils. Our study also demonstrates that a large fraction of the observed WLt variance cannot be explained by nationally available predictor variables and that

  4. Modeling Ice Table Depth, Ground Ice Content, and δD-δ18O of Ground Ice in the Cold Dry Soils of Earth and Mars

    Science.gov (United States)

    Fisher, D. A.; Lacelle, D.; Pollard, W.; Davila, A.; McKay, C. P.

    2016-09-01

    In the upper McMurdo Dry Valleys, ice table depths range from 0 to 80 cm. This study explores the effects of ground temperature and humidity and advective flows on water vapour flux and ice table depth using the REGO vapour-diffusion model.

  5. Influence of water table decline on growth allocation and endogenous gibberellins in black cottonwood

    Energy Technology Data Exchange (ETDEWEB)

    Rood, S.B.; Zanewich, K.; Stefura, C. [Lethbridge Univ., Lethbridge, AB (Canada). Dept. of Biological Sciences; Mahoney, J.M. [Alberta Environmental Protection, Lethbridge, AB (Canada)

    2000-06-01

    Cottonwoods have shown an adaptation to the riparian zone by coordinating root elongation to maintain contact with the water table, whose depth varies with the elevation of the adjacent river. The rate of water decline on growth allocation and concentrations of endogenous gibberellins (GAs) in black cottonwood saplings were studied at the University of Lethbridge, Alberta. Water declines were achieved by using rhizopods, and root elongation approximately doubled in response whereas leaf area was reduced. At some point, a greater water decline rate led to water stress resulting in reduced growth, increased leaf diffusive resistance, decreased water potential, and leaf senescence and abscission. After extraction of endogenous GAs, they were purified and analysed by gas chromatography-selected ion monitoring with internal ({sup 2}H{sub 2})GA standards. The results showed that GAs were higher in shoot tips and sequentially lower in basal stems, root tips, leaves and upper roots. Noticeable relationships did not appear between GA concentration and growth allocation across the water decline treatments. Only GA{sub 8} showed a consistent reduction in plants experiencing water table decline. This research did not permit the authors to conclude whether endogenous GAs play a primary role in the regulation of root elongation in response to water table decline. 7 figs., 25 refs.

  6. How processing digital elevation models can affect simulated water budgets.

    Science.gov (United States)

    Kuniansky, Eve L; Lowery, Mark A; Campbell, Bruce G

    2009-01-01

    For regional models, the shallow water table surface is often used as a source/sink boundary condition, as model grid scale precludes simulation of the water table aquifer. This approach is appropriate when the water table surface is relatively stationary. Since water table surface maps are not readily available, the elevation of the water table used in model cells is estimated via a two-step process. First, a regression equation is developed using existing land and water table elevations from wells in the area. This equation is then used to predict the water table surface for each model cell using land surface elevation available from digital elevation models (DEM). Two methods of processing DEM for estimating the land surface for each cell are commonly used (value nearest the cell centroid or mean value in the cell). This article demonstrates how these two methods of DEM processing can affect the simulated water budget. For the example presented, approximately 20% more total flow through the aquifer system is simulated if the centroid value rather than the mean value is used. This is due to the one-third greater average ground water gradients associated with the centroid value than the mean value. The results will vary depending on the particular model area topography and cell size. The use of the mean DEM value in each model cell will result in a more conservative water budget and is more appropriate because the model cell water table value should be representative of the entire cell area, not the centroid of the model cell.

  7. State-wide space-time water table mapping: cautionary tales, tribulations and resolution

    Science.gov (United States)

    Peterson, T. J.; Cheng, X.; Carrara, E.; Western, A. W.; Costelloe, J. F.; Frost, A. J.; McAuley, C. V.

    2015-12-01

    Historically, insufficient quantitative value has been derived from state groundwater monitoring networks. Water level data are occasionally used for calibrating local scale groundwater models and for graphical analysis, but very rarely are they used to identify regional groundwater processes and quantify changes in groundwater dynamics over time. Potentiometric maps have occasionally been derived to assist understanding of regional processes but generally they are derived for one point in time, often simply using an average water level over a year or season. Consequently, dynamics of regional groundwater over time has been compromised. Kriging with external drift (KED) has been a widely adopted approach for regional scale potentiometric mapping in recent years. However, it has a number of unacknowledged fundamental weaknesses - specifically, excessive noise in the head, sensitivity to observation errors and questionable estimation in upland regions and in coastal regions dominated by radial flow. These weaknesses are illustrated and then a multivariate localised colocated cokriging approach is proposed that locally reduces the excessive noise from KED and incorporates the coast line and streams into the estimation. Combined with the temporal interpolation of groundwater head (Peterson & Western, 2014), the approach allows regional scale mapping for a single point in time. To illustrate the approach, the monthly water table level was mapped across Victoria, Australia, from 1985 to 2014. Using the maps, the location and the nature/magnitude of major changes in groundwater dynamics were identified and the surface-groundwater connectivity of major rivers was estimated over time. While geological knowledge can be incorporated, this approach allows data-driven insights to be derived from groundwater monitoring networks without the usual assumptions required for numerical groundwater modeling. Peterson, T. J., and A. W. Western (2014), Nonlinear time-series modeling of

  8. Effects of site characteristics on cumulative frequency distribution of water table depth in peatlands

    Science.gov (United States)

    Bechtold, Michel; Tiemeyer, Bärbel; Frahm, Enrico; Roßkopf, Niko

    2013-04-01

    Previous studies demonstrated strong dependency of vegetation development and GHG emissions from peatlands on annual mean water table depth. It is also proposed that the duration of ponding and low water level periods are important indicators for CH4 emissions and the presence of specific plant species. Better understanding of the annual water table dynamics and the influence of site characteristics helps to explain variability of vegetation and emissions at the plot scale. It also provides essential information for a nation-wide upscaling of local gas flux measurements and for estimating the impact of regional adaption strategies. In this study, we analyze the influence of site characteristics on the cumulative frequency distribution of water table depth in a peatland. On the basis of data from about 100 sites we evaluate how distribution functions, e.g. the beta distribution function, are a tool for the systematic analysis of the site-specific frequency distribution of water table depth. Our analysis shows that it is possible to differentiate different shape types of frequency distributions, in particular left-skewed (bias towards the water table minimum), right-skewed (bias towards the water table maximum), and 'S'-shaped distributions (bias towards the mid of min and max). The shape is primarily dependent on the annual mean water table depth, but also shows dependencies on land use, peatland type, catchment size and soil properties. Forest soils are for example all characterized by a 'S'-shaped distribution. Preliminary results indicate that data sets that do not show a beta distribution are mostly from observation wells that are located close to drainage courses and/or are from sites characterized by strong water management (e.g. abruptly changing weir levels). The beta distribution might thus be a tool to identify sites with a 'non-natural' frequency distribution or erroneous data sets. Because the parameters of the beta distribution show a dependency on site

  9. Testing of NAPL simulator to predict migration of a light nonaqueous phase liquid (LNAPL) under water table fluctuation in a sandy medium

    Institute of Scientific and Technical Information of China (English)

    周劲风; 李雁; 徐军

    2014-01-01

    Nanoqueous phase liquid (NAPL) simulator is a powerful and popular mathematical model for modeling the flow and transport of non-aqueous phase liquids in subsurface, but the testing of its feasibility under water table fluctuation has received insufficient attention. The feature in a column test was tested through two cycles of water table fluctuation. The sandy medium in the column was initially saturated, and each cycle of water table fluctuation consisted of one water table falling and one rising, resulting in a drainage and an imbibition of the medium, respectively. It was found that the difference between the simulated and measured results in the first drainage of the column test was minor. However, with the propagation of the water table fluctuations, the simulation errors increased, and the simulation accuracy was not acceptable except for the first drainage in the two fluctuation cycles. The main reason was proved to be the estimation method of residual saturation used in this simulator. Also, based on the column tests, it was assumed that the resulting residual saturation from an incomplete imbibition process was a constant, with a value equal to that of the residual value resulting from the main imbibition process. The results obtained after modifying NAPL simulator with this assumption were found to be more accurate in the first cycle of water table fluctuation, but this accuracy decreased rapidly in the second one. It is concluded that NAPL simulator is not adequate in the case of LNAPL migration under water table fluctuation in sandy medium, unless a feasible assumption to estimate residual saturation is put forward.

  10. Stream Water and Soil Water Chemistry Following the Table Mountain Wildfire, Washington

    Science.gov (United States)

    Roccanova, V. J.; Gazis, C. A.

    2013-12-01

    Severe wildfire occurrence in the Western United States increased throughout the 20th century and has continued to increase into the 21st century. Global climate change resulting from natural and anthropogenic sources is considered a contributor to this increase in wildfire severity. Fire suppression techniques developed in the early 20th century are also a factor in increased severe wildfire occurrence as they augment available fuel loads. Biomass burning releases nutrients that are held within trees and plants. Nitrogen, phosphorous, and calcium levels have been documented as increasing in stream waters as a result of wildfire. As severe wildfire occurrence increases, so does the likelihood that stream, and to a lesser extent groundwater, will be loaded with nutrients and sediments as a result of wildfire activity. Increased nutrient loads can cause algal blooms that deplete streams of oxygen, important to aquatic plants and animals that reside in these streams. These changes in water quality can also affect humans who depend on these streams for irrigation and drinking water purposes. The Table Mountain wildfire in Washington State was started by a lightning strike that occurred at approximately 8:00 PM on Saturday September 8th, 2012. The fire burned for approximately one month and was declared to be 100% contained on Friday October 5th, 2012. Over this period the fire burned a total of 171 square kilometers of forest. In this study multiple stream and soil water samples were collected from three types of area in the winter through summer following the fire: severely burned, moderately burned, and unburned. All areas sampled have similar bedrock and vegetation cover. These samples were analyzed for major ions and trace element concentrations. Select samples will also be analyzed for strontium isotope ratios. The results of these geochemical analyses will be presented. Because calcium and strontium have similar properties, their concentrations can be combined

  11. TOPMODEL simulations of streamflow and depth to water table in Fishing Brook Watershed, New York, 2007-09

    Science.gov (United States)

    Nystrom, Elizabeth A.; Burns, Douglas A.

    2011-01-01

    TOPMODEL, a physically based, variable-source area rainfall-runoff model, was used to simulate streamflow and depth to water table for the period January 2007-September 2009 in the 65.6 square kilometers of Fishing Brook Watershed in northern New York. The Fishing Brook Watershed is located in the headwaters of the Hudson River and is predominantly forested with a humid, cool continental climate. The motivation for applying this model at Fishing Brook was to provide a simulation that would be effective later at this site in modeling the interaction of hydrologic processes with mercury dynamics.

  12. Slug tests in wells screened across the water table: some additional considerations.

    Science.gov (United States)

    Butler, J J

    2014-01-01

    The majority of slug tests done at sites of shallow groundwater contamination are performed in wells screened across the water table and are affected by mechanisms beyond those considered in the standard slug-test models. These additional mechanisms give rise to a number of practical issues that are yet to be fully resolved; four of these are addressed here. The wells in which slug tests are performed were rarely installed for that purpose, so the well design can result in problematic (small signal to noise ratio) test data. The suitability of a particular well design should thus always be assessed prior to field testing. In slug tests of short duration, it can be difficult to identify which portion of the test represents filter-pack drainage and which represents formation response; application of a mass balance can help confirm that test phases have been correctly identified. A key parameter required for all slug test models is the casing radius. However, in this setting, the effective casing radius (borehole radius corrected for filter-pack porosity), not the nominal well radius, is required; this effective radius is best estimated directly from test data. Finally, although conventional slug-test models do not consider filter-pack drainage, these models will yield reasonable hydraulic conductivity estimates when applied to the formation-response phase of a test from an appropriately developed well.

  13. Response of anaerobic carbon cycling to water table manipulation in an Alaskan rich fen

    Science.gov (United States)

    Kane, E.S.; Chivers, M.R.; Turetsky, M.R.; Treat, C.C.; Petersen, D.G.; Waldrop, M.; Harden, J.W.; McGuire, A.D.

    2013-01-01

    To test the effects of altered hydrology on organic soil decomposition, we investigated CO2 and CH4 production potential of rich-fen peat (mean surface pH = 6.3) collected from a field water table manipulation experiment including control, raised and lowered water table treatments. Mean anaerobic CO2 production potential at 10 cm depth (14.1 ± 0.9 μmol C g−1 d−1) was as high as aerobic CO2 production potential (10.6 ± 1.5 μmol C g−1 d−1), while CH4 production was low (mean of 7.8 ± 1.5 nmol C g−1 d−1). Denitrification enzyme activity indicated a very high denitrification potential (197 ± 23 μg N g−1 d−1), but net NO-3 reduction suggested this was a relatively minor pathway for anaerobic CO2 production. Abundances of denitrifier genes (nirK and nosZ) did not change across water table treatments. SO2-4 reduction also did not appear to be an important pathway for anaerobic CO2 production. The net accumulation of acetate and formate as decomposition end products in the raised water table treatment suggested that fermentation was a significant pathway for carbon mineralization, even in the presence of NO-3. Dissolved organic carbon (DOC) concentrations were the strongest predictors of potential anaerobic and aerobic CO2 production. Across all water table treatments, the CO2:CH4 ratio increased with initial DOC leachate concentrations. While the field water table treatment did not have a significant effect on mean CO2 or CH4 production potential, the CO2:CH4 ratio was highest in shallow peat incubations from the drained treatment. These data suggest that with continued drying or with a more variable water table, anaerobic CO2 production may be favored over CH4 production in this rich fen. Future research examining the potential for dissolved organic substances to facilitate anaerobic respiration, or alternative redox processes that limit the effectiveness of organic acids as substrates in anaerobic metabolism, would help explain additional

  14. Application of Cooling Water in Controlled Runout Table Cooling on Hot Strip Mill

    Institute of Scientific and Technical Information of China (English)

    LIU Zheng-dong; I V Samarasekera

    2004-01-01

    The controlled runout table cooling is essential in determining the final mechanical properties and flatness of steel strip. The heat of a hot steel strip is mainly extracted by cooling water during runout. In order to study the heat transfer by water jet impingement boiling during runout, a pilot facility was constructed at the University of British Columbia. On this pilot facility, the water jet impingement tests were carried out under various cooling conditions to investigate the effect of processing parameters, such as cooling water temperature, water jet impingement velocity, initial strip temperature, water flow rate, water nozzle diameter and array of water nozzles, on the heat transfer of heated strip. The results obtained contribute to the optimization of cooling water during runout.

  15. Reducing nitrate loss in tile drainage water with cover crops and water-table management systems.

    Science.gov (United States)

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

    2014-03-01

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

  16. Effects of a fluctuating water table : Column study on redox dynamics and fate of some organic pollutants

    NARCIS (Netherlands)

    Sinke, A.J.C.; Dury, O.; Zobrist, J.

    1998-01-01

    The development of the redox conditions has been studied in an initially aerobic column filled with quartz sand coated with ferrihydrite and subjected to a fluctuating water table. The purpose of this study was to evaluate the effect of water table fluctuations on the redox dynamics and the fate of

  17. Upper Bound Solution for the Face Stability of Shield Tunnel below the Water Table

    Directory of Open Access Journals (Sweden)

    Xilin Lu

    2014-01-01

    Full Text Available By FE simulation with Mohr-Coulomb perfect elastoplasticity model, the relationship between the support pressure and displacement of the shield tunnel face was obtained. According to the plastic strain distribution at collapse state, an appropriate failure mechanism was proposed for upper bound limit analysis, and the formula to calculate the limit support pressure was deduced. The limit support pressure was rearranged to be the summation of soil cohesion c, surcharge load q, and soil gravity γ multiplied by their corresponding coefficients Nc, Nq, and Nγ, and parametric studies were carried out on these coefficients. In order to consider the influence of seepage on the face stability, the pore water pressure distribution and the seepage force on the tunnel face were obtained by FE simulation. After adding the power of seepage force into the equation of the upper bound limit analysis, the total limit support pressure for stabilizing the tunnel face under seepage condition was obtained. The total limit support pressure was shown to increase almost linearly with the water table.

  18. Disposal of high-level nuclear waste above the water table in arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Roseboom, E.H. Jr.

    1983-12-31

    Locating a repository in the unsaturated zone of arid regions eliminates or simplifies many of the technological problems involved in designing a repository for operation below the water table and predicting its performance. It also offers possible accessibility and ease of monitoring throughout the operational period and possible retrieval of waste long after. The risks inherent in such a repository appear to be no greater than in one located in the saturated zone; in fact, many aspects of such a repository`s performance will be much easier to predict and the uncertainties will be reduced correspondingly. A major new concern would be whether future climatic changes could produce significant consequences due to possible rise of the water table or increased flux of water through the repository. If spent fuel were used as a waste form, a second new concern would be the rates of escape of gaseous {sup 129}I and {sup 14}C to the atmosphere.

  19. Subsymmetry and asymmetry models for multiway square contingency tables with ordered categories

    Directory of Open Access Journals (Sweden)

    Aktaş Serpil

    2016-01-01

    Full Text Available This paper suggests several models that describe the symmetry and asymmetry structure of each subdimension for the multiway square contingency table with ordered categories. A classical three-way categorical example is examined to illustrate the model results. These models analyze the subsymmetric and asymetric structure of the table.

  20. Sulfuric acid speleogenesis (SAS) close to the water table: Examples from southern France, Austria, and Sicily

    Science.gov (United States)

    De Waele, Jo; Audra, Philippe; Madonia, Giuliana; Vattano, Marco; Plan, Lukas; D'Angeli, Ilenia M.; Bigot, Jean-Yves; Anoux, Catherine; Nobécourt, Jean-Claude

    2016-01-01

    Caves formed by rising sulfuric waters have been described from all over the world in a wide variety of climate settings, from arid regions to mid-latitude and alpine areas. H2S is generally formed at depth by reduction of sulfates in the presence of hydrocarbons and is transported in solution through the deep aquifers. In tectonically disturbed areas major fractures eventually allow these H2S-bearing fluids to rise to the surface where oxidation processes can become active producing sulfuric acid. This extremely strong acid reacts with the carbonate bedrock creating caves, some of which are among the largest and most spectacular in the world. Production of sulfuric acid mostly occurs at or close to the water table but also in subaerial conditions in moisture films and droplets in the cave environment. These caves are generated at or immediately above the water table, where condensation-corrosion processes are dominant, creating a set of characteristic meso- and micromorphologies. Due to their close connection to the base level, these caves can also precisely record past hydrological and geomorphological settings. Certain authigenic cave minerals, produced during the sulfuric acid speleogenesis (SAS) phase, allow determination of the exact timing of speleogenesis. This paper deals with the morphological, geochemical and mineralogical description of four very typical sulfuric acid water table caves in Europe: the Grotte du Chat in the southern French Alps, the Acqua Fitusa Cave in Sicily (Italy), and the Bad Deutsch Altenburg and Kraushöhle caves in Austria.

  1. Behavioral modeling of microwave power amplifiers using a look up table method

    NARCIS (Netherlands)

    Shen, Y.; Gajadharsing, J.; Tauritz, J.L.

    2007-01-01

    The possibility of building a microwave power amplifier (PA) behavioral model based on the look-up table principle is investigated. The model so constructed avoids the difficulties in model structure selection and/or its parameter estimation.

  2. The role of sustained water table drawdown and wildfire on C emissions in boreal peatlands

    Science.gov (United States)

    Kotowska, A.; Turetsky, M. R.; Benscoter, B.

    2011-12-01

    Northern peatlands store up to 370 Pg C, or ~80% of boreal soil carbon (C). In general, peat accumulates where water table (WT) levels at or near the soil surface lead to high primary productivity and low rates of decomposition. However, increased evapotranspiration under warmer, drier conditions predicted for boreal peatlands under future climate change are expected to decrease seasonal WT levels and increase the potential for deep peat fires. The effects of long-term changes in hydrology on northern peatland vegetation and C cycling are not well understood, nor are the effects of wildfire on interactions between C cycling and peatland hydrology. The objective of this study was to examine the net effects of fire and long-term water table drawdown on CO2 and CH4 fluxes. We utilized a rich fen impacted by road construction in the early 1990's and a bog that experienced a severe fire 4 years prior to study initiation to examine drought and fire disturbances, respectively. We found that 20 years of sustained WT drawdown had no effect on understory net ecosystem exchange (NEE) of CO2. However, WT drawdown did increase ecosystem respiration (ER) and gross primary productivity (GPP) relative to pristine plots. WT drawdown also altered the response of GPP to light availability and WT position, as well as the temperature sensitivity (Q10) of ER. Surprisingly, mean CH4 emissions did not change as a result of WT drawdown, though fewer ebullition events were observed in the drought plot. Four years post-fire, NEE was higher (net C sink) in the burned plot compared to the unburned (75 years since fire) plot. As expected, we found a negative relationship between ER and WT in the unburned plot, but this pattern was reversed in the burned plot, where ER was highest under relatively wet conditions. Despite lower plant cover in the burned plot, there were no differences in GPP between the sites, indicating high photosynthetic capacity in surviving and newly-colonizing vegetation

  3. 40 CFR Table 4 to Subpart Dddd of... - Model Rule-Toxic Equivalency Factors

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Model Rule-Toxic Equivalency Factors 4... or Before November 30, 1999 Pt. 60, Subpt. DDDD, Table 4 Table 4 to Subpart DDDD of Part 60—Model Rule—Toxic Equivalency Factors Dioxin/furan congener Toxic equivalency factor 2,3,7,8-tetrachlorinated...

  4. A Mathematical View of Water Table Fluctuations in a Shallow Aquifer in Brazil

    NARCIS (Netherlands)

    Neto, Dagmar C.; Chang, Hung K.; van Genuchten, Martinus Th

    Detailed monitoring of the groundwater table can provide important data about both short- and long-term aquifer processes, including information useful for estimating recharge and facilitating groundwater modeling and remediation efforts. In this paper, we presents results of 4years (2002 to 2005)

  5. A Mathematical View of Water Table Fluctuations in a Shallow Aquifer in Brazil

    NARCIS (Netherlands)

    Neto, Dagmar C.; Chang, Hung K.; van Genuchten, Martinus Th

    2016-01-01

    Detailed monitoring of the groundwater table can provide important data about both short- and long-term aquifer processes, including information useful for estimating recharge and facilitating groundwater modeling and remediation efforts. In this paper, we presents results of 4years (2002 to 2005) o

  6. Mitigation of greenhouse gas fluxes from cultivated organic soils by raised water table

    OpenAIRE

    Regina, Kristiina

    2010-01-01

    Cultivated organic soils are a remarkable source of greenhouse gases (GHG) in some countries and raised ground water table has been suggested as a mitigation measure on these soils. Drainage of the peat increases mineralization of the organic matter and causes high emissions of carbon dioxide (CO2) and nitrous oxide (N2O) while emissions of methane (CH4) are lowered compared to pristine peatlands. In countries with a large area of organic soils these GHG emissions can be remarkable. In ...

  7. Annual safe groundwater yield in a semiarid basin using combination of water balance equation and water table fluctuation

    Science.gov (United States)

    Rezaei, Abolfazl; Mohammadi, Zargham

    2017-10-01

    The safe groundwater yield plays a major role in the appropriate management of groundwater systems, particularly in (semi-)arid areas like Iran. This study incorporates both the water balance equation and the water table fluctuation to estimate the annual safe yield of the unconfined aquifer in the eastern part of the Kaftar Lake, an Iranian semiarid region. Firstly, the water balance year 2002-03, owing same water table elevation at the beginning and year-end, was chosen from the monthly representative groundwater hydrograph of the aquifer to be taken into account as a basic water year for determining the safe yield. Then the ratio of the total groundwater pumping to the annual groundwater recharge in the selected water balance year together with the quantity of total recharge occurred in the wet period (October to May) of the year of interest were applied to evaluate the annual safe yield at the initiation of the dry period (June to September) of the year of interest. Knowing the annual safe groundwater withdrawal rate at the initiation of each dry period could be helpful to decision makers in managing groundwater resources conservation. Analysis results indicate that to develop a safe management strategy in the aquifer; the ratio of the annual groundwater withdrawal to the annually recharged volume should not exceed 0.69. In the water year 2003-04 where the ratio is equal to 0.52, the water table raised up (about 0.48 m) while the groundwater level significantly declined (about 1.54 m) over the water year 2007-08 where the ratio of the annual groundwater withdrawal to the annually recharged volume (i.e., 2.76) is larger than 0.69.

  8. Subsidence and soil CO2 efflux in tropical peatland in southern Thailand under various water table and management conditions

    Directory of Open Access Journals (Sweden)

    T. Nagano

    2013-12-01

    Full Text Available At the Bacho peatland in southern Thailand, peat subsidence was measured at four locations on abandoned agricultural land (degraded peat swamp forest and at one location in a conservation zone, at monthly intervals over a period of more than 20 years. Average peat subsidence rates during the observation period were 3.1–5.2 cm y−1 on the degraded peatland, reducing to 1.8–2.6 cm y−1 when peat loss due to field fires was discounted, and 1.0 cm y−1 reducing to 0.7 cm y-1 in the conservation zone. Due to martial law restrictions on access to the Bacho site, measurements of the peat soil respiration rate under various water table conditions were made mostly at other sites in Thailand with similar climate. During these measurements the position of the water table ranged from 0.92 m above the peat surface to more than one metre below it, and daily mean respiration rates ranged from 0.57 to 8.20 μmol CO2 m−2 s−1. The CO2 efflux attributed to peat respiration was 13.7–18.9 Mg ha−1 y−1 on the degraded peatland but only 7.5 Mg ha−1 y−1 in the conservation zone. To simulate the CO2 efflux resulting from soil respiration at Bacho on the basis of data collected elsewhere, we developed an empirical three-stage model (NAIS Peat Model that treats the position of the water table as a proxy variable. The observed values of peat subsidence were in good agreement with simulated values of CO2 efflux in two tests. The implications for peatland management are considered.

  9. The EPANET water quality model

    Energy Technology Data Exchange (ETDEWEB)

    Rossman, L.A. [Environmental Protection Agency, Cincinnati, OH (United States)

    1995-10-01

    EPANET is a software package developed by US EPA`s Drinking Water Research Division for modeling hydraulic and water quality behavior within water distribution systems. Starting with a geometric description of the pipe network, a set of initial conditions, estimates of water usage, and a set of rules for how the system is operated, EPANET predicts all flows, pressures, and water quality levels throughout the network during an extended period of operation. In addition to substance concentration, water age and source tracing can also be simulated. EPANET offers a number of advanced features including: modular, highly portable C language code with no pre-set limits on network size; a simple data input format based on a problem oriented language; a full-featured hydraulic simulator; improved water quality algorithms; analysis of water quality reactions both within the bulk flow and at the pipe wall; an optional graphical user interface running under Microsoft{reg_sign} Windows{trademark}. The Windows user interface allows one to edit EPANET input files, run a simulation, and view the results all within a single program. Simulation output can be visualized through: color-coded maps of the distribution system with full zooming, panning and labeling capabilities and a slider control to move forward or backward through time; spreadsheet-like tables that can be searched for entries meeting a specified criterion; and time series graphs of both predicted and observed values for any variable at any location in the network. EPANET is currently being used to analyze a number of water quality issues in different distribution systems across the country. These include: chlorine decay dynamics, raw water source blending, altered tank operation, and integration with real-time monitoring and control systems.

  10. Complex of computer models for cold stress evaluation in water

    OpenAIRE

    І. I. Ermakova; N. G. Ivanushkina; A. Yu. Nikolaenko; Yu. N. Solopchuk

    2015-01-01

    Introduction. Due to the high value of water thermal conductivity comparing to air, stay of man in cold water (water temperature lower than 25 sup>°C) is associated with high life and health hazard. One of the ways to evaluate survival time of human in water is usage of statistics data about survivors and water temperature organized as tables and curves. Another method to evaluate survival time and physiological state of man in water is computer modelling of human thermoregulatory system. ...

  11. SteamTablesGrid: An ActiveX control for thermodynamic properties of pure water

    Science.gov (United States)

    Verma, Mahendra P.

    2011-04-01

    An ActiveX control, steam tables grid ( StmTblGrd) to speed up the calculation of the thermodynamic properties of pure water is developed. First, it creates a grid (matrix) for a specified range of temperature (e.g. 400-600 K with 40 segments) and pressure (e.g. 100,000-20,000,000 Pa with 40 segments). Using the ActiveX component SteamTables, the values of selected properties of water for each element (nodal point) of the 41×41 matrix are calculated. The created grid can be saved in a file for its reuse. A linear interpolation within an individual phase, vapor or liquid is implemented to calculate the properties at a given value of temperature and pressure. A demonstration program to illustrate the functionality of StmTblGrd is written in Visual Basic 6.0. Similarly, a methodology is presented to explain the use of StmTblGrd in MS-Excel 2007. In an Excel worksheet, the enthalpy of 1000 random datasets for temperature and pressure is calculated using StmTblGrd and SteamTables. The uncertainty in the enthalpy calculated with StmTblGrd is within ±0.03%. The calculations were performed on a personal computer that has a "Pentium(R) 4 CPU 3.2 GHz, RAM 1.0 GB" processor and Windows XP. The total execution time for the calculation with StmTblGrd was 0.3 s, while it was 60.0 s for SteamTables. Thus, the ActiveX control approach is reliable, accurate and efficient for the numerical simulation of complex systems that demand the thermodynamic properties of water at several values of temperature and pressure like steam flow in a geothermal pipeline network.

  12. Estimating groundwater evapotranspiration by a subtropical pine plantation using diurnal water table fluctuations: Implications from night-time water use

    Science.gov (United States)

    Fan, Junliang; Ostergaard, Kasper T.; Guyot, Adrien; Fujiwara, Stephen; Lockington, David A.

    2016-11-01

    Exotic pine plantations have replaced large areas of the native forests for timber production in the subtropical coastal Australia. To evaluate potential impacts of changes in vegetation on local groundwater discharge, we estimated groundwater evapotranspiration (ETg) by the pine plantation using diurnal water table fluctuations for the dry season of 2012 from August 1st to December 31st. The modified White method was used to estimate the ETg, considering the night-time water use by pine trees (Tn). Depth-dependent specific yields were also determined both experimentally and numerically for estimation of ETg. Night-time water use by pine trees was comprehensively investigated using a combination of groundwater level, sap flow, tree growth, specific yield, soil matric potential and climatic variables measurements. Results reveal a constant average transpiration flux of 0.02 mm h-1 at the plot scale from 23:00 to 05:00 during the study period, which verified the presence of night-time water use. The total ETg for the period investigated was 259.0 mm with an accumulated Tn of 64.5 mm, resulting in an error of 25% on accumulated evapotranspiration from the groundwater if night-time water use was neglected. The results indicate that the development of commercial pine plantations may result in groundwater losses in these areas. It is also recommended that any future application of diurnal water table fluctuation based methods investigate the validity of the zero night-time water use assumption prior to use.

  13. Uses and Limitations of Scientific Models: The Periodic Table as an Inductive Tool.

    Science.gov (United States)

    Ben-Zvi, Nava; Genut, Sara

    1998-01-01

    Demonstrates that scientific laws about nature and their representative models, as taught and described by theory, are often different from the method as practiced. Focuses on the use of the Periodic Table as a scientific model. Contains 26 references. (DDR)

  14. Coastal groundwater table estimation by an elevation fluctuation neural model

    Institute of Scientific and Technical Information of China (English)

    HE Bin; WANG Yi

    2007-01-01

    Restrictions of groundwater management are often derived from the insufficient or missing groundwater database. A suitable and complete groundwater database will allow sound engineering plans for sustainable water usage, including the drilling of wells, rates of water withdrawal, and eventually artificial recharge of the aquifer. The spatial-temporal variations of groundwater monitoring data are fluently influenced by the presence of manual factors, monitor equipment malfunctioning, natural phenomena, etc. Thus, it is necessary for researchers to check and infill the groundwater database before running the numerical groundwater model. In this paper, an artificial neural network (ANN)-based model is formulated using the hydrological and meteorological data to infill the inadequate data in the groundwater database. Prediction results present that ANN method could be a desirable choice for estimating the missing groundwater data.

  15. Computer generated track and field scoring tables: II. Theoretical foundation and development of a model.

    Science.gov (United States)

    Purdy, J G

    1975-01-01

    An investigation is made into the subject of scoring tables for track and field with emphasis on the application of computers to calculate and output the tables. The resulting scoring tables represent an attempt to describe the effective quality of performance for track and field events. This paper is published in three parts. The first portion reviewed the historical development of scoring tables. This part concerns the theoretical foundation and development of a mathematical model. A set of underlying principles and construction guidelines are established as a basis for all scoring tables. In order to satisfy the goals, a model which includes an exponential term is developed. The concept of a zero offset is introduced as a boundary value for the low-level performances. The final part concerns an evaluation of the model and an analysis of the point scores for different events.

  16. Multi-decadal water-table manipulation alters peatland hydraulic structure and moisture retention.

    Science.gov (United States)

    Moore, Paul; Morris, Paul; Waddington, James

    2015-04-01

    Peatlands are a globally important store of freshwater and soil carbon. However, there is a concern that these water and carbon stores may be at risk due to climate change as vapour pressure deficits, evapotranspiration and summer moisture deficits are expected to increase, leading to greater water table (WT) drawdown in northern continental regions where peatlands are prevalent. We argue that in order to evaluate the hydrological response (i.e. changes in WT level, storage, surface moisture availability, and moss evaporation) of peatlands under future climate change scenarios, the hydrophysical properties of peat and disparities between microforms must be well understood. A peatland complex disturbed by berm construction in the 1950's was used to examine the long-term impact of WT manipulation on peatland hydraulic properties and moisture retention at three adjacent sites with increasing average depth to WT (WET, INTermediate reference, and DRY). All three sites exhibited a strong depth dependence for hydraulic conductivity, specific yield, and bulk density. Moreover, the effect of microform on near-surface peat properties tended to be greater than the site effect. Bulk density was found to explain a high amount of variance (r2 > 0.69) in moisture retention across a range of pore water pressures (-15 to -500 cm H2O), where bulk density tended to be higher in hollows. The estimated residual water content for surface Sphagnum samples, while on average lower in hummocks (0.082 m3 m-3) versus hollows (0.087 m3 m-3), increased from WET (0.058 m3 m-3) to INT (0.088 m3 m-3) to DRY (0.108 m3 m-3) which has important implications for moisture stress under conditions of persistent WT drawdown. While we did not observe significant differences between sites, we did observe a greater proportional coverage and greater relative height of hummocks at the drier sites. Given the potential importance of microtopographic succession for altering peatland hydraulic structure, our

  17. Spatial relationship of groundwater arsenic distribution with regional topography and water-table fluctuations in the shallow aquifers in Bangladesh

    Science.gov (United States)

    Shamsudduha, M.; Marzen, L. J.; Uddin, A.; Lee, M.-K.; Saunders, J. A.

    2009-06-01

    The present study has examined the relationship of groundwater arsenic (As) levels in alluvial aquifers with topographic elevation, slope, and groundwater level on a large basinal-scale using high-resolution (90 m × 90 m) Shuttle Radar Topography Mission (SRTM) digital elevation model and water-table data in Bangladesh. Results show that high As (>50 μg/l) tubewells are located in low-lying areas, where mean surface elevation is approximately 10 m. Similarly, high As concentrations are found within extremely low slopes (Bangladesh Water Development Board) was mapped using water-table data from 950 shallow (depth Works Datum (PWD) level. Extremely low groundwater gradients (0.01-0.001 m/km) within the GBM delta complex hinder groundwater flow and cause slow flushing of aquifers. Low elevation and gentle slope favor accumulation of finer sediments, As-carrying iron-oxyhydroxide minerals, and abundant organic matter within floodplains and alluvial deposits. At low horizontal hydraulic gradients and under reducing conditions, As is released in groundwater by microbial activity, causing widespread contamination in the low-lying deltaic and floodplain areas, where As is being recycled with time due to complex biogeochemical processes.

  18. Linking Water Table Dynamics to Carbon Cycling in Artificial Soil Column Incubations

    Science.gov (United States)

    Geertje, Pronk; Adrian, Mellage; Tatjana, Milojevic; Fereidoun, Rezanezhad; Cappellen Philippe, Van

    2016-04-01

    The biogeochemistry of wetlands soils is closely tied to their hydrology. Water table fluctuations that cause flooding and drying of these systems may lead to enhanced degradation of organic matter and release of greenhouse gasses (e.g. CO2, CH4) to the atmosphere. However, predicting the influence of water table fluctuations on the biogeochemical functioning of soils requires an understanding of the interactions of soil hydrology with biogeochemical and microbial processes. To determine the effects of water table dynamics on carbon cycling, we are carrying out state-of-the-art automated soil column experiments with fully integrated monitoring of hydro-bio-geophysical process variables under both constant and oscillating water table conditions. An artificial, homogeneous mixture consisting of minerals and organic matter is used to provide a well-defined starting material. The artificial soils are composed of quartz sand, montmorillonite, goethite and humus from a forested riparian zone, from which we also extracted the microbial inoculum added to the soil mixture. The artificial soils are packed into 60 cm high, 7.5 cm wide columns. In the currently ongoing experiment, three replicate columns are incubated while keeping the water table constant water at mid-depth, while another three columns alternate between drained and saturated conditions. Micro-sensors installed at different depths below the soil surface record time-series redox potentials (Eh) varying between oxidizing (~+700 mV) and reducing (~-200 mV) conditions. Continuous O2 levels throughout the soil columns are monitored using high-resolution, luminescence-based, Multi Fiber Optode (MuFO) microsensors. Pore waters are collected periodically with MicroRhizon samplers from different depths, and analyzed for pH, EC, dissolved inorganic and organic carbon and ion/cation compositions. These measurements allow us to track the changes in pore water geochemistry and relate them to differences in carbon cycling

  19. Revised water table elevations and depths for 1978 and 1979, Closed Basin Division, San Luis Vallet Project, Colorado

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Memorandum with revised contour map overlays for the highest and lowest elevations and deepest and shallowest depths of the water table in 1978 and 1979 for the...

  20. Investigation of Seismic Behavior of Container Crane Structures by Shake Table Tests and Mathematical Modeling

    Directory of Open Access Journals (Sweden)

    C. Oktay Azeloglu

    2014-01-01

    Full Text Available This paper is concerned with the verification of mathematical modeling of the container cranes under earthquake loadings with shake table test results. Comparison of the shake table tests with the theoretical studies has an important role in the estimation of the seismic behavior of the engineering structures. For this purpose, a new shake table and mathematical model were developed. Firstly, a new physical model is directly fixed on the shake table and the seismic response of the container crane model against the past earthquake ground motion was measured. Secondly, a four degrees-of-freedom mathematical model is developed to understand the dynamic behaviour of cranes under the seismic loadings. The results of the verification study indicate that the developed mathematical model reasonably represents the dynamic behaviour of the crane structure both in time and frequency domains. The mathematical model can be used in active-passive vibration control studies to decrease structural vibrations on container cranes.

  1. "Periodic-table-style" paper device for monitoring heavy metals in water.

    Science.gov (United States)

    Li, Miaosi; Cao, Rong; Nilghaz, Azadeh; Guan, Liyun; Zhang, Xiwang; Shen, Wei

    2015-03-03

    If a paper-based analytical device (μ-PAD) could be made by printing indicators for detection of heavy metals in chemical symbols of the metals in a style of the periodic table of elements, it could be possible for such μ-PAD to report the presence and the safety level of heavy metal ions in water simultaneously and by text message. This device would be able to provide easy solutions to field-based monitoring of heavy metals in industrial wastewater discharges and in irrigating and drinking water. Text-reporting could promptly inform even nonprofessional users of the water quality. This work presents a proof of concept study of this idea. Cu(II), Ni(II), and Cr(VI) were chosen to demonstrate the feasibility, specificity, and reliability of paper-based text-reporting devices for monitoring heavy metals in water.

  2. Water-table contours, directions of ground-water movement, and measurements of inflow to American Falls Reservoir, Southeastern Idaho, April 1984

    Science.gov (United States)

    Young, H.W.

    1984-01-01

    In 1978 the U.S. Geological Survey began a 5-year study of the High Plains regional aquifer system to provide hydrologic information for evaluating the effects of long-term development of the aquifer and to develop a capability for predicting aquifer response to alternative changes in ground-water management. By use of a digital model, this report presents a quantitative description of the High Plains aquifer in Oklahoma. The High Plains aquifer consists predominantly of the Tertiary Ogallala Formation and overlying Quaternary alluvium and terrace deposits which are hydraulically connected to the High Plains aquifer. Much of the aquifer is underlain by formations of Permian through Cretaceous age, which generally have very small hydraulic conductivities. In some areas parts of underlying Triassic, Jurassic, or Cretaceous rocks are hydraulically connected with the aquifer. The High Plains aquifer is a water-table aquifer in which water moves generally to the east-southeast. Before the beginning of extensive irrigation of the 1960's, the aquifer was essentially in dynamic equilibrium with recharge from precipitation balanced by natural discharge from the aquifer. Ground-water discharge appeared in streams leaving the area or was returned to the atmosphere through evapotranspiration. Accurate records of irrigation pumpage are not available from the High Plains. In order to estimate irrigation pumpage, published records of crop distribution were used and a consumptive use was assigned to each principal irrigated crop. This method gave an estimated irrigation demand. Pumpage was taken as a percentage of the total irrigation demand. Irrigation has decreased ground-water discharge from the High Plains aquifer. Ground-water discharge was estimated as approximately 118 cubic feet per second in 1980. A finite-difference digital model was used to simulate flow in the High Plains aquifer. The recharge was adjusted so that 1980 ground-water discharge was 118 cubic feet per

  3. News from the Periodic Table: An Introduction to "Periodicity Symbols, Tables, and Models for Higher-Order Valency and Donor-Acceptor Kinships"

    Science.gov (United States)

    Bent, Henry A.; Weinhold, Frank

    2007-01-01

    The study presents and explains the various periodicity symbols, tables and models for the higher-order valency and donor-acceptor kinships used in chemistry. The described alternative tables are expected to improve the pedagogical consistency of the chemical periodicity patterns with better electronic behavior.

  4. News from the Periodic Table: An Introduction to "Periodicity Symbols, Tables, and Models for Higher-Order Valency and Donor-Acceptor Kinships"

    Science.gov (United States)

    Bent, Henry A.; Weinhold, Frank

    2007-01-01

    The study presents and explains the various periodicity symbols, tables and models for the higher-order valency and donor-acceptor kinships used in chemistry. The described alternative tables are expected to improve the pedagogical consistency of the chemical periodicity patterns with better electronic behavior.

  5. Responses of CO2 emission and pore water DOC concentration to soil warming and water table drawdown in Zoige Peatlands

    Science.gov (United States)

    Yang, Gang; Wang, Mei; Chen, Huai; Liu, Liangfeng; Wu, Ning; Zhu, Dan; Tian, Jianqing; Peng, Changhui; Zhu, Qiuan; He, Yixin

    2017-03-01

    Peatlands in Zoige Plateau contains more than half of peatland carbon stock in China. This part of carbon is losing with climate change through dissolved organic carbon (DOC) export and carbon dioxide (CO2) emissions, both of which are vulnerable to the environmental changes, especially on the Zoige Plateau with a pace of twice the observed rate of global climate warming. This research aimed to understand how climate change including soil warming, rainfall reduction and water table change affect CO2 emissions and whether the trends of changes in CO2 emission are consistent with those of pore water DOC concentration. A mesocosm experiment was designed to investigate the CO2 emission and pore water DOC during the growing seasons of 2009-2010 under scenarios of passive soil warming, 20% rainfall reduction and changes to the water table levels. The results showed a positive relationship between CO2 emission and DOC concentration. For single factor effect, we found no significant relationship between water table and CO2 emission or DOC concentration. However, temperature at 5 cm depth was found to have positive linear relationship with CO2 emission and DOC concentration. The combined effect of soil warming and rainfall reduction increased CO2 emission by 96.8%. It suggested that the drying and warming could stimulate potential emission of CO2. Extending this result to the entire peatland area in Zoige Plateau translates into 0.45 Tg CO2 emission per year over a growing season. These results suggested that the dryer and warmer Zoige Plateau will increase CO2 emission. We also found the contribution rate of DOC concentration to CO2 emission was increased by 12.1% in the surface layer and decreased by 13.8% in the subsurface layer with combined treatment of soil warming and rainfall reduction, which indicated that the warmer and dryer environmental conditions stimulate surface peat decomposition process.

  6. Classification errors in contingency tables analyzed with hierarchical log-linear models. Technical report No. 20

    Energy Technology Data Exchange (ETDEWEB)

    Korn, E L

    1978-08-01

    This thesis is concerned with the effect of classification error on contingency tables being analyzed with hierarchical log-linear models (independence in an I x J table is a particular hierarchical log-linear model). Hierarchical log-linear models provide a concise way of describing independence and partial independences between the different dimensions of a contingency table. The structure of classification errors on contingency tables that will be used throughout is defined. This structure is a generalization of Bross' model, but here attention is paid to the different possible ways a contingency table can be sampled. Hierarchical log-linear models and the effect of misclassification on them are described. Some models, such as independence in an I x J table, are preserved by misclassification, i.e., the presence of classification error will not change the fact that a specific table belongs to that model. Other models are not preserved by misclassification; this implies that the usual tests to see if a sampled table belong to that model will not be of the right significance level. A simple criterion will be given to determine which hierarchical log-linear models are preserved by misclassification. Maximum likelihood theory is used to perform log-linear model analysis in the presence of known misclassification probabilities. It will be shown that the Pitman asymptotic power of tests between different hierarchical log-linear models is reduced because of the misclassification. A general expression will be given for the increase in sample size necessary to compensate for this loss of power and some specific cases will be examined.

  7. Potential of Ground Penetrating Radar for the characterization of the shallow water table in the Mnasra region in Morocco

    Directory of Open Access Journals (Sweden)

    Imane SEBARI

    2016-03-01

    Full Text Available Morocco is a water-scarce country confronted with a severe dependence on rain-fed agriculture and dwindling groundwater reserves. Since 1995, new water regulation laws and management strategies have been promulgated providing a comprehensive framework for an integrated management. Moreover, water managers should have precise data on the current state of water tables depth in strategic aquifers. Unfortunately, the main source of these data are sporadic wells with no automated monitoring systems making the assessment of water table dynamics, costly, time consuming and out-phased with decision maker needs. In this respect, this paper focuses on the capability of Ground Penetrating Radar to determine the depth of shallow water table in Mnasra region, located in the Gharb region of Morocco as a pilot study to generalize its use in the future for groundwater dynamic monitoring purposes in Morocco. The experiment was undertaken using Mala 800 MHz shielded antennas and was able to probe the depth of the upper fresh water table at 3.75 m deep in the Mnasra aquifer in semi-arid conditions. Data collected by GPR can be used as substitute for well logs to enhance the monitoring of water tables in stressed areas during droughts and excessive recharges during rainy season.

  8. Measuring the Change in Water Table with Gravity Methods - a Controlled Experiment

    DEFF Research Database (Denmark)

    Lund, S; Christiansen, Lars; Andersen, O. B.

    2009-01-01

    in water content, a controlled experiment was set up in 30 m by 20 m basin. The water table was lowered 0.69 m within 1½ hours and the corresponding gravity signal measured using two different approaches: a time series measurements at one location and a gravity network measurement including four points....... Both where in agreement with the calculated maximum theoretical gravity change of 27*10^-8 m/s^2. Uncertainties on the change in gravity in the network measurements where 4*10^-8 m/s^2 (one standard deviation). This corresponds to an infinite horizontal slab of water with a thickness of 0.1 m. The time...

  9. Determination of vulnerability areas to pollution: case of alluvial water table of Tebessa (East Algeria)

    Energy Technology Data Exchange (ETDEWEB)

    Djabri, L.; Hani, A.; Assassi, F.; Djprfi, S.

    2009-07-01

    This work related to the alluvial water table of Tebessa, which is characterised by a semi-dry climate and a very heterogeneous geology. To examine the pollution problem who seems exists, we have used two methods: the DRASTICS method who combines the information given by the seven parameters leading to the map of vulnerability to pollution and a second method that is based on hydrochemistry and take into account the results of the ratio Sr{sup 2}/Ca{sup 2}+. (Author)

  10. Bathymetric surveys and area/capacity tables of water-supply reservoirs for the city of Cameron, Missouri, July 2013

    Science.gov (United States)

    Huizinga, Richard J.

    2014-01-01

    Years of sediment accumulation and dry conditions in recent years have led to the decline of water levels and capacities for many water-supply reservoirs in Missouri, and have caused renewed interest in modernizing outdated area/capacity tables for these reservoirs. The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, surveyed the bathymetry of the four water-supply reservoirs used by the city of Cameron, Missouri, in July 2013. The data were used to provide water managers with area/capacity tables and bathymetric maps of the reservoirs at the time of the surveys.

  11. Estimating quasi-loglinear models for a Rasch table if the numbers of items is large

    NARCIS (Netherlands)

    Kelderman, Henk

    1987-01-01

    The Rasch Model and various extensions of this model can be formulated as a quasi loglinear model for the incomplete subgroup x score x item response 1 x ... x item response k contingency table. By comparing various loglinear models, specific deviations of the Rasch model can be tested. Parameter es

  12. Peatland pines as a proxy for water table fluctuations: disentangling tree growth, hydrology and possible human influence.

    Science.gov (United States)

    Smiljanić, Marko; Seo, Jeong-Wook; Läänelaid, Alar; van der Maaten-Theunissen, Marieke; Stajić, Branko; Wilmking, Martin

    2014-12-01

    Dendrochronological investigations of Scots pine (Pinus sylvestris L.) growing on Männikjärve peatland in central Estonia showed that annual tree growth of peatland pines can be used as a proxy for past variations of water table levels. Reconstruction of past water table levels can help us to better understand the dynamics of various ecological processes in peatlands, e.g. the formation of vegetation patterns or carbon and nitrogen cycling. Männikjärve bog has one of the longest water table records in the boreal zone, continuously monitored since 1956. Common uncertainties encountered while working with peatland trees (e.g. narrow, missing and wedging rings) were in our case exacerbated with difficulties related to the instability of the relationship between tree growth and peatland environment. We hypothesized that the instable relationship was mainly due to a significant change of the limiting factor, i.e. the rise of the water table level due to human activity. To test our hypothesis we had to use several novel methods of tree-ring chronology analysis as well as to test explicitly whether undetected missing rings biased our results. Since the hypothesis that the instable relationship between tree growth and environment was caused by a change in limiting factor could not be rejected, we proceeded to find possible significant changes of past water table levels using structural analysis of the tree-ring chronologies. Our main conclusions were that peatland pines can be proxies to water table levels and that there were several shifting periods of high and low water table levels in the past 200 years. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Effect of taxonomic resolution on ecological and palaeoecological inference - a test using testate amoeba water table depth transfer functions

    Science.gov (United States)

    Mitchell, Edward A. D.; Lamentowicz, Mariusz; Payne, Richard J.; Mazei, Yuri

    2014-05-01

    Sound taxonomy is a major requirement for quantitative environmental reconstruction using biological data. Transfer function performance should theoretically be expected to decrease with reduced taxonomic resolution. However for many groups of organisms taxonomy is imperfect and species level identification not always possible. We conducted numerical experiments on five testate amoeba water table (DWT) transfer function data sets. We sequentially reduced the number of taxonomic groups by successively merging morphologically similar species and removing inconspicuous species. We then assessed how these changes affected model performance and palaeoenvironmental reconstruction using two fossil data sets. Model performance decreased with decreasing taxonomic resolution, but this had only limited effects on patterns of inferred DWT, at least to detect major dry/wet shifts. Higher-resolution taxonomy may however still be useful to detect more subtle changes, or for reconstructed shifts to be significant.

  14. Effects of soil water table regime on tree community species richness and structure of alluvial forest fragments in Southeast Brazil

    Directory of Open Access Journals (Sweden)

    AC. Silva

    Full Text Available In order to determine the influence of soil water table fluctuation on tree species richness and structure of alluvial forest fragments, 24 plots were allocated in a point bar forest and 30 plots in five forest fragments located in a floodplain, in the municipality of São Sebastião da Bela Vista, Southeast Brazil, totalizing 54, 10 X 20 m, plots. The information recorded in each plot were the soil water table level, diameter at breast height (dbh, total height and botanical identity off all trees with dbh > 5 cm. The water table fluctuation was assessed through 1 m deep observation wells in each plot. Correlations analysis indicated that sites with shallower water table in the flooding plains had a low number of tree species and high tree density. Although the water table in the point bar remained below the wells during the study period, low tree species richness was observed. There are other events taking place within the point bar forest that assume a high ecological importance, such as the intensive water velocity during flooding and sedimentation processes.

  15. Effectiveness of table top water pitcher filters to remove arsenic from drinking water.

    Science.gov (United States)

    Barnaby, Roxanna; Liefeld, Amanda; Jackson, Brian P; Hampton, Thomas H; Stanton, Bruce A

    2017-10-01

    Arsenic contamination of drinking water is a serious threat to the health of hundreds of millions of people worldwide. In the United States ~3 million individuals drink well water that contains arsenic levels above the Environmental Protection Agency (EPA) maximum contaminant level (MCL) of 10μg/L. Several technologies are available to remove arsenic from well water including anion exchange, adsorptive media and reverse osmosis. In addition, bottled water is an alternative to drinking well water contaminated with arsenic. However, there are several drawbacks associated with these approaches including relatively high cost and, in the case of bottled water, the generation of plastic waste. In this study, we tested the ability of five tabletop water pitcher filters to remove arsenic from drinking water. We report that only one tabletop water pitcher filter tested, ZeroWater®, reduced the arsenic concentration, both As(3+) and As(5+), from 1000μg/L to water and its use reduces plastic waste associated with bottled water. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  16. The impact of water table drawdown and drying on subterranean aquatic fauna in in-vitro experiments.

    Directory of Open Access Journals (Sweden)

    Christine Stumpp

    Full Text Available The abstraction of groundwater is a global phenomenon that directly threatens groundwater ecosystems. Despite the global significance of this issue, the impact of groundwater abstraction and the lowering of groundwater tables on biota is poorly known. The aim of this study is to determine the impacts of groundwater drawdown in unconfined aquifers on the distribution of fauna close to the water table, and the tolerance of groundwater fauna to sediment drying once water levels have declined. A series of column experiments were conducted to investigate the depth distribution of different stygofauna (Syncarida and Copepoda under saturated conditions and after fast and slow water table declines. Further, the survival of stygofauna under conditions of reduced sediment water content was tested. The distribution and response of stygofauna to water drawdown was taxon specific, but with the common response of some fauna being stranded by water level decline. So too, the survival of stygofauna under different levels of sediment saturation was variable. Syncarida were better able to tolerate drying conditions than the Copepoda, but mortality of all groups increased with decreasing sediment water content. The results of this work provide new understanding of the response of fauna to water table drawdown. Such improved understanding is necessary for sustainable use of groundwater, and allows for targeted strategies to better manage groundwater abstraction and maintain groundwater biodiversity.

  17. The feasibility of thermal inertia mapping for detection of perched water tables in semi-arid irrigated lands

    Science.gov (United States)

    Ezra, C. E.; Estes, J. E.; Bonn, F.

    1982-01-01

    The thermal inertia mapping remote sensing technique is evaluated as a potential method for delineating areas of shallow perched water tables and related salinization problems on a regional basis. This method for detecting shallow water tables is based on the existence of significant differences in soil thermal properties between wet and dry soil profiles. Ground observations were conducted at two different test sites in California along the flight line, with one site located in a perched water table area and the other site in a well drained area. Measurements were taken hourly during a four day period (two days before and two days after the flight) for variables such as radiometric, meteorologic, soil moisture and temperature profiles, and surface characteristics. Results indicate that it is not feasible using present apparent thermal inertia remote sensing techniques to reliably delineate regional patterns of very shallow water tables due to the complex environmental system. However, some features within specific fields which may be directly related to the local presence of shallow water tables, such as differences in evaporative cooling due to soil moisture effects between and within fields, can be detected using the thermal inertia technique.

  18. Inferring the heterogeneity, transmissivity and hydraulic conductivity of crystalline aquifers from a detailed water-table map

    Science.gov (United States)

    Dewandel, Benoît; Jeanpert, Julie; Ladouche, Bernard; Join, Jean-Lambert; Maréchal, Jean-Christophe

    2017-07-01

    Estimating the transmissivity or hydraulic conductivity field to characterize the heterogeneity of a crystalline aquifer is particularly difficult because of the wide variations of the parameters. We developed a new approach based on the analysis of a dense network of water-table data. It is based on the concept that large-scale variations in hydraulic head may give information on large-scale aquifer parameters. The method assumes that flux into the aquifer is mainly sub-horizontal and that the water table is mostly controlled by topography, rather than recharge. It is based on an empirical statistical relationship between field data on transmissivity and the inverse slope values of a topography-reduced water-table map. This relationship is used to compute a transmissivity map that must be validated with field measurements. The proposed approach can provide a general pattern of transmissivity, or hydraulic conductivity, but cannot correctly reproduce strong variations at very local scale (less than10 m), and will face of some uncertainties where vertical flows cannot be neglected. The method was tested on a peridotite (ultramafic rock) aquifer of 3.5 km2 in area located in New Caledonia. The resulting map shows transmissivity variations over about 5 orders of magnitude (average LogT: -5.2 ± 0.7). Comparison with a map based on measured water-level data (n = 475) shows that the comparison between LogT-computed values and LogT data deduced from 28 hydraulic tests is estimated with an error less than 20% in 71% of cases (LogT ± 0.4), and with an error less than 10% (LogT ± 0.2 on average) in 39% of cases. From this map a hydraulic-conductivity map has been computed showing values ranging over 8 orders of magnitude. The repeatability of the approach was tested on a second data set of hydraulic-head measurements (n = 543); the mean deviation between both LogT maps is about 11%. These encouraging results show that the method can give valuable parameter estimates, and

  19. CO2 phase mutation by fluctuating water table in the vadose zone over a CCS site

    Science.gov (United States)

    Joun, W.; Ha, S. W.; Kim, H. H.; Kim, T. W.; Lee, S. S.; Lee, K. K.

    2015-12-01

    Geological sequestration of carbon dioxide (CO2) is one of the feasible plans to control greenhouse gas emissions. In order to be more perfect, the plan has to prove that the injected CO2 gas will not be leaking. Even if CO2 leaking happens, we should possess a technique which provides information on specific aquifer system before critical effect to ground and subsurface environments. Many parameters have been utilized for early detection before risk to environments by sensing CO2 gas concentration, electric conductivity, pH, and ion analysis. However, these are not enough to all CCS sites for leakage detection. For example, the importance of gas leaking path is emphasized because finding the dominant gas flow path can reduce risk and provide a quick estimation. Herein, we investigate dissolved solute degassing and vertical flow from saturated zone to unsaturated zone in shallow depth aquifer. Especially we focused on the water table fluctuation effect. Based on field data and basic parameters, we perform a pilot scale gas injection test and calculate gas flow saturation with STOMP simulator. The CO2 gas concentrations at different depth levels according to amount of injected CO2 infused water, CO2 gas saturation in vadose zone have different concentration values. If we estimate this phenomenon in vadose zone by using CO2 gas detection method, we could presume that the CO2 dissolved in shallow groundwater is degassing and flow upward into vadose zone. However, the concentration level and change patterns are not same and will be changed according to the pattern of water table fluctuation. This study could be usefully applied to strategic CCS environmental monitoring of CO2 leakage.Acknowledgement: Financial support was provided by the "R&D Project on Environmental Management of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003).

  20. Evaluation of a mechanistic algorithm to calculate the influence of a shallow water table on hydrology sediment and pesticide transport through vegetative filter strips

    Science.gov (United States)

    Lauvernet, C.; Munoz-Carpena, R.; Carluer, N.

    2012-04-01

    Natural or introduced areas of vegetation, also known as vegetative filter strips (VFS), are a common environmental control practice to protect surface water bodies from human influence. In Europe, VFS are placed along the water network to protect from agrochemical drift during applications, in addition to runoff control. Their bottomland placement next to the streams often implies the presence of a seasonal shallow water table which can have a profound impact on the efficiency of the buffer zone (Lacas et al. 2005). A physically-based algorithm describing ponded infiltration into soils bounded by a water table, proposed by Salvucci and Enthekabi (1995), was further developed to simulate VFS dynamics by making it explicit in time, account for unsteady rainfall conditions, and by coupling to a numerical overland flow and transport model (VFSMOD) (Munoz-Carpena et al., submitted). In this study, we evaluate the importance of the presence of a shallow water table on filter efficiency (reductions in runoff, sediment and pesticide mass), in the context of all other input factors used to describe the system. Global sensitivity analysis (GSA) was used to rank the important input factors and the presence of interactions, as well as the contribution of the important factors to the output variance. GSA of VSFMOD modified for shallow water table was implemented on 2 sites selected in France because they represent different agro-pedo-climatic conditions for which we can compare the role of the factors influencing the performance of grassed buffer strips for surface runoff, sediment and pesticide removal. The first site at Morcille watershed in the Beaujolais wineyard (Rhône-Alpes) contains a very permeable sandy-clay with water table depth varying with the season (very deep in summer and shallow in winter), with a high slope (20 to 30%), and subject to strong seasonal storms (semi-continental, Mediterranean climate). The second site at La Jailliere (Loire-Atlantique, ARVALIS

  1. Large water-table response to rainfall in a shallow bedrock aquifer having minimal overburden cover

    Science.gov (United States)

    Miles, Owen W.; Novakowski, Kent S.

    2016-10-01

    Rapid recharge events manifested as significant increases in hydraulic head have been observed in many fractured bedrock aquifers around the world. Often the response in hydraulic head exceeds what would be observed in an equivalent porous media by more than an order of magnitude. As the mechanisms that cause these events are poorly understood particularly under highly-transient conditions, a detailed investigation was conducted at a well-characterized field site in eastern Canada. During the spring and summer of 2012, frequent measurements of hydraulic head were obtained in gneissic terrain covered by a thin veneer of drift materials using 21 multi-level monitoring wells installed in the bedrock. Each of the wells was hydraulically tested from the water table to total depth using a straddle-packer system and fractures intersecting the wells were identified using a borehole camera prior to the construction of the multi-level piezometers. Rainfall and weather data were also collected over the same time period. A piezometer located on a bedrock outcrop which responded rapidly to rainfall was identified and used as a focus for numerical simulations. To determine the properties of the drift materials in the vicinity of the outcrop, a ground penetrating radar (GPR) survey was conducted over a 40 × 40 m area to map depth to bedrock and five in-situ permeameter tests were performed to estimate the hydraulic conductivity. Three-dimensional numerical simulations were conducted to reproduce the response in the piezometer for both short (24 h) and long (one month) timescales. The numerical simulations were used to determine what parameters have the greatest impact on controlling rapid recharge. Based on this study it was concluded that the large magnitude head rises recorded in this piezometer are a result of recharge to steeply inclined fractures exposed on or immediately adjacent to the outcrop. The hydraulic head responds rapidly because of the low specific yield of the

  2. EPANET water quality model

    Energy Technology Data Exchange (ETDEWEB)

    Rossman, L.A.

    1993-01-01

    EPANET represents a third generation of water quality modeling software developed by the U.S. EPA's Drinking Water Research Division, offering significant advances in the state of the art for network water quality analysis. EPANET performs extended period simulation of hydraulic and water quality behavior within water distribution systems. In addition to substance concentration, water age and source tracing can also be simulated. EPANET includes a full featured hydraulic simulation model that can handle various types of pumps, valves, and their control rules. The water quality module is equipped to handle constituent reactions within the bulk pipe flow and at the pipe wall. It also features an efficient computational scheme that automatically determines optimal time steps and pipe segmentation for accurate tracking of material transport over time. EPANET is currently being used in the US to study such issues as loss of chlorine residual, source blending and trihalomethane (THM) formation, how altered tank operation affects water age, and total dissolved solids (TDS) control for an irrigation network.

  3. Stream Water Quality Model

    Data.gov (United States)

    U.S. Environmental Protection Agency — QUAL2K (or Q2K) is a river and stream water quality model that is intended to represent a modernized version of the QUAL2E (or Q2E) model (Brown and Barnwell 1987).

  4. Time-Dependent Networks as Models to Achieve Fast Exact Time-Table Queries

    DEFF Research Database (Denmark)

    Brodal, Gert Stølting; Jacob, Rico

    2003-01-01

    We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries for travelers using a train system. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models.......We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries for travelers using a train system. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models....

  5. Time-dependent Networks as Models to Achieve Fast Exact Time-table Queries

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Jacob, Rico

    2001-01-01

    We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models.......We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models....

  6. DEVELOPMENT OF SORGHUM PLANTS SUBMITTED UNDER DIFFERENT WATER TABLE LEVELS IN GLASSHOUSE

    Directory of Open Access Journals (Sweden)

    Adriana Aki Tanaka

    2014-03-01

    Full Text Available DESENVOLVIMENTO DE PLANTAS DE SORGO SUBMETIDAS A DIFERENTES NÍVEIS DE LENÇOL FREÁTICO EM CASA DE VEGETAÇÃO O objetivo deste trabalho foi avaliar o desenvolvimento das plantas de sorgo (Sorghum bicolor L. Moench submetidas a diferentes níveis de lençol freático. O projeto foi realizado em casa de vegetação de vidro, sobre bandejas com reservatórios de água que permitiam a subirrigação e vasos constituídos de tubos de PVC (15 cm de diâmetro com diferentes alturas simulando diferentes níveis de lençol freático com cinco profundidades (0,17 m; 0,31 m; 0,45 m; 0,59 m; 0,73 m, tratamentos T1; T2; T3; T4; T5 e T6 respectivamente, em delineamento inteiramente casualizado. Os parâmetros analisados foram: massa da matéria fresca e seca, altura e diâmetro do colmo das plantas; massa da matéria fresca e seca e comprimento das panículas; massa da matéria seca das raízes total; área foliar; número de folhas; evapotranspiração da cultura (ETc; coeficiente da cultura (Kc. T3 e T4 foram os melhores, apresentando os maiores valores para ambas as massas, fresca e seca. Para as panículas, os maiores valores para as massas de matéria fresca e seca e comprimento foram apresentados por T4 e T5. Para o diâmetro do colmo não houve significância estatística entre T3, T4 e T5. Plantas cultivadas em níveis freáticos mais próximos da superfície induziram a produção de colmos mais grossos. Palavras-chave: características agronômicas, evapotranspiração, coeficiente da cultura. ABSTRACT This study aimed to evaluate the sorghum plants development (Sorghum bicolor L. Moench submitted to different water table levels. The experiment was carried out in a glasshouse on trays with water reservoirs that allowed sub irrigation, and PVC tubes (15 cm diameter with different heights simulating five water table levels (17 cm; 31 cm; 45 cm; 59 cm; 73 cm, treatments T1; T2; T3; T4; T5 respectively, in an entirely random design. The analyzed

  7. Non-methane biogenic volatile organic compound emissions from boreal peatland microcosms under warming and water table drawdown

    DEFF Research Database (Denmark)

    Faubert, P; Tiiva, P; Nakam, TA

    2011-01-01

    BVOC groups. Only isoprene emission was significantly increased by warming, parallel to the increased leaf number of the dominant sedge Eriophorum vaginatum. BVOC emissions from peat soil were higher under the control and warming treatments than water table drawdown, suggesting an increased activity...... assessed the combined effect of warming and water table drawdown on the BVOC emissions from boreal peatland microcosms. We also assessed the treatment effects on the BVOC emissions from the peat soil after the 7-week long experiment. Emissions of isoprene, monoterpenes, sesquiterpenes, other reactive VOCs...... and other VOCs were sampled using a conventional chamber technique, collected on adsorbent and analyzed by GC–MS. Carbon emitted as BVOCs was less than 1% of the CO2 uptake and up to 3% of CH4 emission. Water table drawdown surpassed the direct warming effect and significantly decreased the emissions of all...

  8. The interplay between rainfall infiltration depth, rooting depth and water table depth in regulating Amazon evapotranspiration (ET)

    Science.gov (United States)

    Miguez-Macho, Gonzalo; Fan, Ying; Dominguez, Francina

    2017-04-01

    Plants link the subsurface to the atmosphere via water and carbon fluxes and are therefore a key player in climate. The Amazon, one of Earth's largest ecosystems, is an important climate regulator. As a large source of evapotranspiration, it has significant influence on regional and remote precipitation dynamics. For its equatorial position, it impacts significantly the global climate engine. The Amazon receives abundant annual rainfall but parts of it experience a multi-month dry season. Here we elucidate the interplay among three hydrological depths: precipitation infiltration depth, root water uptake-depth, and the water table depth in regulating dry-season ET, using inverse modeling based on observed productivity, ERA Interim reanalysis atmosphere, and a novel integrated soil-surface-groundwater model with dynamic root uptake to meet the transpiration demand. We perform high-resolution ( 1km) multi-year simulations over the region, with shallow soil, deep soil, with and without groundwater, with and without dynamic rooting depth; attempting to tease out these components. The results demonstrate the strong interactions among the three depths and what each factor does in regulating dry season ET, shedding light on how future global change may preferentially impact Amazon ecosystem functioning.

  9. Coupling water table fluctuation to mercury speciation and transport in wetland ecosystems

    Science.gov (United States)

    Branfireun, B. A.; Mitchell, C. P.

    2008-12-01

    Hydrological processes exert a first-order control over both the conditions required for mercury methylation to occur, and the transport of methylmercury from sites of production. In the recent literature, evidence has been presented that a relationship exists between water level fluctuation and mercury levels in aquatic organisms. These observations have led to the conclusion that this fluctuation is stimulating mercury methylation in littoral sediments and wetland ecosystems through the creation of favourable biogeochemical conditions. Using data from a range of wetland ecosystems, and several experiments that subjected wetland soils to fluctuating water levels, a relationship between water table fluctuation frequency and methylmercury production will be presented. Experimental data show that longer frequency wetting and drying periods result in greater methylmercury production relative to a static or high frequency fluctuation. It was also found that mercury methylation processes in wetland soils are able to sustain elevated pore water concentrations over repeated wetting and draining events. These data suggest that methylmercury export from wetlands is likely limited by the degree of hydrological connectivity rather than biogeochemical processes, highlighting the need to better understand the nature of hydrological linkages among wetlands and adjacent ecosystems.

  10. Geophysical Contribution in the Characterization of Deep Water Tables Geometry (Sidi Bouzid, Central Tunisia

    Directory of Open Access Journals (Sweden)

    D. Khazri

    2015-01-01

    Full Text Available Geophysical data combined with geological and hydrogeological data were analyzed to characterize the geometry of Oued El Hajel and Ouled Asker deep water tables (Sidi Bouzid. The obtained results allowed refining the geostructural schema by highlighting the individualization of the NE-SW underground convexity of Ouled Asker and the anticline of axis Es Souda-Hmaeima and Ezaouia on either sides of two hydrogeological thresholds. The geometrical analysis determined the spatial extension of Ouled Asker and Oued El Hajel subbasins. The seismic cartography of semideep and deep reservoirs (Oligo-Miocene; Eocene and upper Cretaceous associated with the main subbasins contributed to proposing hydrogeological prospect zones for a rationalized groundwater exploitation.

  11. Iron-mediated soil carbon response to water-table decline in an alpine wetland

    Science.gov (United States)

    Wang, Yiyun; Wang, Hao; He, Jin-Sheng; Feng, Xiaojuan

    2017-06-01

    The tremendous reservoir of soil organic carbon (SOC) in wetlands is being threatened by water-table decline (WTD) globally. However, the SOC response to WTD remains highly uncertain. Here we examine the under-investigated role of iron (Fe) in mediating soil enzyme activity and lignin stabilization in a mesocosm WTD experiment in an alpine wetland. In contrast to the classic `enzyme latch' theory, phenol oxidative activity is mainly controlled by ferrous iron [Fe(II)] and declines with WTD, leading to an accumulation of dissolvable aromatics and a reduced activity of hydrolytic enzyme. Furthermore, using dithionite to remove Fe oxides, we observe a significant increase of Fe-protected lignin phenols in the air-exposed soils. Fe oxidation hence acts as an `iron gate' against the `enzyme latch' in regulating wetland SOC dynamics under oxygen exposure. This newly recognized mechanism may be key to predicting wetland soil carbon storage with intensified WTD in a changing climate.

  12. Preparation of testate amoebae samples affects water table depth reconstructions in peatland palaeoecological studies

    Directory of Open Access Journals (Sweden)

    Eve Avel

    2013-05-01

    Full Text Available In peatland palaeoecological studies, the preparation of peat samples for testate amoebae (TA analysis involves boiling of samples and microsieving them through a 15-μm sieve. We studied the effect of these preparation stages on the estimation of TA assemblages and on the reconstruction of water table depths (WTD. Our results indicate that the TA assemblages of boiled and unboiled samples are not significantly different, while microsieving reduces the concentration of small TA taxa and results in significantly different TA assemblages. The differences between microsieved and unsieved TA assemblages were reflected also in predicted values of WTD, which indicated drier conditions in case of unsieved samples than in microsieved samples. We conclude that the boiling of samples might be omitted if TA are extracted from the fresh peat samples. Microsieving may lead to erroneous palaeoecological WTD reconstructions and should be avoided if small TA taxa are present in samples.

  13. Rotating water table for the determination of non-steady forces in a turbine stage through modified hydraulic analogy

    Science.gov (United States)

    Rao, J. S.; Raghavacharyulu, E.; Seshadri, V.; Rao, V. V. R.

    1983-10-01

    Determination of non-steady forces in a real turbine stage is difficult due to the local flow conditions, for example high pressures, high temperatures and in-accessibility to the region etc. Experimentation in a real turbine is also prohibitive due to the costs involved. An alternate method of arriving at these non-steady forces through the use of modified hydraulic analogy is discussed. A rotating water table facility, developed and fabricated based on the principles of modified hydraulic analogy is described. A flat plate stage is simulated on the rotating water table, and the results obtained are presented.

  14. Rotating Water Table for the Determination of Non-Steady Forces in a Turbine Stage Through Modified Hydraulic Analogy

    Directory of Open Access Journals (Sweden)

    J. S. Rao

    1983-10-01

    Full Text Available Determination of non-steady forces in a real turbine stage is difficult due to the local flow conditions, for example high pressures, high temperatures and in-accessibility to the region etc. Experimentation in a real turbine is also prohibitive due to the costs involved. An alternate method of arriving at these non-steady forces through the use of modified hydraulic analogy is discussed. A rotating water table facility, developed and fabricated based on the principles of modified hydraulic analogy ia described. A flat plate stage is simulated on the rotating water table, and the results obtalned are presented.

  15. Electrical Resistivity Imaging of Tidal Fluctuations in the Water Table at Inwood Hill Park, Manhattan

    Science.gov (United States)

    Kenyon, P. M.; Kassem, D.; Olin, A.; Nunez, J.; Smalling, A.

    2005-05-01

    Inwood Hill Park is located on the northern tip of Manhattan and has been extensively modified over the years by human activities. In its current form, it has a backbone of exposed or lightly covered bedrock along the Hudson River, adjacent to a flat area with two tidal inlets along the northern shore of Manhattan. The tidal motions in the inlets are expected to drive corresponding fluctuations in the water table along the borders of the inlets. In the Fall of 2002, a group of students from the Department of Earth and Atmospheric Sciences at the City College of New York studied these fluctuations. Electrical resistivity cross sections were obtained with a Syscal Kid Switch 24 resistivity meter during the course of a tidal cycle at three locations surrounding the westernmost inlet in the park. No change was seen over a tidal cycle at Site 1, possibly due to the effect of concrete erosion barriers which were located between the land and the water surrounding this site. Measurements at Site 2 revealed a small, regular change in the water table elevation of approximately 5 cm over the course of a tidal cycle. This site is inferred to rest on alluvial sediments deposited by a small creek. The cross sections taken at different times during a tidal cycle at Site 3 were the most interesting. They show a very heterogeneous subsurface, with water spurting between blocks of high resistivity materials during the rising portion of the cycle. A small sinkhole was observed on the surface of the ground directly above an obvious plume of water in the cross section. Park personnel confirmed that this sinkhole, like others scattered around this site, is natural and not due to recent construction activity. They also indicated that debris from the construction of the New York City subways may have been dumped in the area in the past. Our conclusion is that the tidal fluctuations at Site 3 are being channeled by solid blocks in the construction debris, and that the sinkholes currently

  16. A novel automated fluctuating water table column system to study redox oscillations in saturated and unsaturated media

    Science.gov (United States)

    Rezanezhad, F.; Couture, R.-M.; Kovac, R.; Van Cappellen, P.

    2012-04-01

    An automated, computer-controlled soil column experimental setup was developed to simulate in detail the effects of water table dynamics on the biogeochemical transformations of nutrients and other redox-sensitive chemical species at the interface between groundwater and surface waters. The experiments were conducted using two parallel soil columns, one under stable and the other under fluctuating water table conditions. The water table in the soil columns was controlled by an automated multi-channel pump connected to two equilibrium and storage columns. In the stable column, the water table was maintained at -20 cm below the soil surface while it fluctuated between the soil surface and -45 cm in the fluctuating column at a rate of 4.8 cm/d. Redox potential (Eh), pH profiles were measured continuously using high temporal resolution microsensors (10 μm glass tip) installed into the columns at different depths. The results show striking geochemical contrasts between the fluctuating and the stable columns, demonstrating that the setup is able to impose redox potential oscillations ranging from oxidizing (~+700 mv) to reducing (~-200 mv) conditions. CO2 fluxes were monitored in the headspace above the soil surface using a LICOR LI-8100 automated soil CO2 flux system. The mean CO2 emission in the stable water table column was ~20 ppm/min. In the fluctuating soil column, the CO2 flux varied between 4 and 110 ppm/min and the lowest were measured at the highest water level. Water samples obtained from micro-Rhizon samplers installed into the columns at various depths. Additionally, the physical, chemical and microbial characteristics of the media were characterized by centimetre scale slicing of the soil columns at the end of the experiment. The impacting of these oscillations on the distribution of chemical species will be discussed in term of the interactions between soils, solutes, microbial activity, and hydrology.

  17. Water-table height and microtopography control biogeochemical cycling in an Arctic coastal tundra ecosystem

    Science.gov (United States)

    Lipson, D. A.; Zona, D.; Raab, T. K.; Bozzolo, F.; Mauritz, M.; Oechel, W. C.

    2012-01-01

    Drained thaw lake basins (DTLB's) are the dominant land form of the Arctic Coastal Plain in northern Alaska. The presence of continuous permafrost prevents drainage and so water tables generally remain close to the soil surface, creating saturated, suboxic soil conditions. However, ice wedge polygons produce microtopographic variation in these landscapes, with raised areas such as polygon rims creating more oxic microenvironments. The peat soils in this ecosystem store large amounts of organic carbon which is vulnerable to loss as arctic regions continue to rapidly warm, and so there is great motivation to understand the controls over microbial activity in these complex landscapes. Here we report the effects of experimental flooding, along with seasonal and spatial variation in soil chemistry and microbial activity in a DTLB. The flooding treatment generally mirrored the effects of natural landscape variation in water-table height due to microtopography. The flooded portion of the basin had lower dissolved oxygen, lower oxidation-reduction potential (ORP) and higher pH, as did lower elevation areas throughout the entire basin. Similarly, soil pore water concentrations of organic carbon and aromatic compounds were higher in flooded and low elevation areas. Dissolved ferric iron (Fe(III)) concentrations were higher in low elevation areas and responded to the flooding treatment in low areas, only. The high concentrations of soluble Fe(III) in soil pore water were explained by the presence of siderophores, which were much more concentrated in low elevation areas. All the aforementioned variables were correlated, showing that Fe(III) is solubilized in response to anoxic conditions. Dissolved carbon dioxide (CO2) and methane (CH4) concentrations were higher in low elevation areas, but showed only subtle and/or seasonally dependent effects of flooding. In anaerobic laboratory incubations, more CH4 was produced by soils from low and flooded areas, whereas anaerobic CO2

  18. 天水鲜食葡萄水分适宜性研究%A study on water suitability of table grape in Tianshui

    Institute of Scientific and Technical Information of China (English)

    姚小英; 李晓薇; 王禹锡; 汪鸿滨

    2013-01-01

    Based on the observation data of phenology of table grape at Tianshui Agro-meteorological Experiment Station from 2004 to 2009 and the meteorological data at Maiji National Base Meteorological Station from 1971 to 2009, the water requirement of table grape during various growing periods had been calculated with the FAO Penman-Monteith formula (1998 edition) and crop coefficients, and the model of water suitability degree of table grape had been set up. The results showed that the water supply in Tianshui was comparatively advantageous to table grape and the mean water suitability degree of whole growing season was above 0.70. The water suitability degree of whole growth season decreased with the times in recent years. Although the mean water suitability degree of whole growing season was relatively good, it was uneven among different growing periods. The precipitation was more than the amount of water requirement during the late growing period, but there was a remarkable water deficiency and the water suitability degree was relatively low during vigorous growing period. It was suggested that, in order to improve the industry of table grape sustainably, irrigation facilities be developed preferentially in the mountain areas in Tianshui.%运用甘肃省天水农业气象试验站2004-2009年葡萄物候观测资料及1971-2009年的气象资料,利用Penman-Monteith(98版)公式及作物系数,对葡萄各生育阶段的需水量进行计算,建立估算水分利用程度的水分适宜度模型.结果表明:天水市葡萄生长期的水分条件比较优越,全生育期水分适宜度在0.70以上;近年来全生育期葡萄水分适宜度随时间呈下降状态;虽然全生育期水分适宜性较好,但在各生长阶段分布不均,末期生长阶段降水量大于需水量,但旺盛生长期水分供需矛盾比较突出,水分适宜度较低.在半山区建园应该优先发展灌溉等农业设施,以利于葡萄种植业的持续发展.

  19. Modelling and simulation for table tennis referee regulation based on finite state machine.

    Science.gov (United States)

    Cui, Jianjiang; Liu, Zixuan; Xu, Long

    2017-10-01

    As referee's decisions are made artificially in traditional table tennis matches, many factors in a match, such as fatigue and subjective tendency, may lead to unjust decision. Based on finite state machine (FSM), this paper presents a model for table tennis referee regulation to substitute manual decisions. In this model, the trajectory of the ball is recorded through a binocular visual system while the complete rules extracted from the International Table Tennis Federation (ITTF) rules are described based on FSM. The final decision for the competition is made based on expert system theory. Simulation result shows that the proposed model has high accuracy, and can be generalised to other similar games such as badminton, volleyball, etc.

  20. Real-time 4D ERT monitoring of river water intrusion into a former nuclear disposal site using a transient warping-mesh water table boundary (Invited)

    Science.gov (United States)

    Johnson, T.; Hammond, G. E.; Versteeg, R. J.; Zachara, J. M.

    2013-12-01

    The Hanford 300 Area, located adjacent to the Columbia River in south-central Washington, USA, is the site of former research and uranium fuel rod fabrication facilities. Waste disposal practices at site included discharging between 33 and 59 metric tons of uranium over a 40 year period into shallow infiltration galleries, resulting in persistent uranium contamination within the vadose and saturated zones. Uranium transport from the vadose zone to the saturated zone is intimately linked with water table fluctuations and river water intrusion driven by upstream dam operations. As river stage increases, the water table rises into the vadose zone and mobilizes contaminated pore water. At the same time, river water moves inland into the aquifer, and river water chemistry facilitates further mobilization by enabling uranium desorption from contaminated sediments. As river stage decreases, flow moves toward the river, ultimately discharging contaminated water at the river bed. River water specific conductance at the 300 Area varies around 0.018 S/m whereas groundwater specific conductance varies around 0.043 S/m. This contrast provides the opportunity to monitor groundwater/river water interaction by imaging changes in bulk conductivity within the saturated zone using time-lapse electrical resistivity tomography. Previous efforts have demonstrated this capability, but have also shown that disconnecting regularization constraints at the water table is critical for obtaining meaningful time-lapse images. Because the water table moves with time, the regularization constraints must also be transient to accommodate the water table boundary. This was previously accomplished with 2D time-lapse ERT imaging by using a finely discretized computational mesh within the water table interval, enabling a relatively smooth water table to be defined without modifying the mesh. However, in 3D this approach requires a computational mesh with an untenable number of elements. In order to

  1. Periodic Properties and Inquiry: Student Mental Models Observed during a Periodic Table Puzzle Activity

    Science.gov (United States)

    Larson, Kathleen G.; Long, George R.; Briggs, Michael W.

    2012-01-01

    The mental models of both novice and advanced chemistry students were observed while the students performed a periodic table activity. The mental model framework seems to be an effective way of analyzing student behavior during learning activities. The analysis suggests that students do not recognize periodic trends through the examination of…

  2. Periodic Properties and Inquiry: Student Mental Models Observed during a Periodic Table Puzzle Activity

    Science.gov (United States)

    Larson, Kathleen G.; Long, George R.; Briggs, Michael W.

    2012-01-01

    The mental models of both novice and advanced chemistry students were observed while the students performed a periodic table activity. The mental model framework seems to be an effective way of analyzing student behavior during learning activities. The analysis suggests that students do not recognize periodic trends through the examination of…

  3. Hillslope and stream connections to water tables in montane meadows of the southern Sierra Nevada, California

    Science.gov (United States)

    Conklin, M. H.; Lucas, R. G.

    2011-12-01

    Montane meadows are often areas of groundwater discharge. In this study we characterized the groundwater - surface water interactions of two meadow systems and their connectivity to the surrounding catchment . We analyzed groundwater elevation data in 24 wells in two meadows located in the southern Sierra Nevada. Well transects extended from the meadow centers near the stream, to the meadow edged, and into the adjacent forest-where wells were drilled into the weathered granite saprock layer. Water samples were collected from the monitoring wells and from streams associated with the meadow systems and analyzed for major ions and stable water isotopes. Ground water elevations in the monitoring wells were used to calculate daily evapotranspiration (ET) values. These values show that locations on the meadow slopes and near the meadow edges are losing water to the atmosphere at near potential evapotranspiration rates during the height of the growing season. ET signals from wells near the meadow streams are muted, likely due to the vegetation utilizing the available surface water at these locations. Wells installed in the saprock layer, outside of the meadow boundaries, show diurnal fluctuations in sync with fluctuations observed at the meadow edge. This trend persists after the meadow vegetation senesces, indicating that groundwater elevations in the meadow, especially near the meadow edge, are significantly influenced by the adjacent hillslope saprock layer and forest ET. Geochemical sampling results indicate that the meadow streams are predominantly fed by snowmelt in the spring and early summer, moving toward more influence from base flow in the late summer and early fall. Results from the geochemical analysis established the connections of the hillslope to the meadow water tables and of the meadow subsurface waters to the down-gradient streams. Our results indicate that the these meadows are directly connected to the shallow sub-surface processes in the up gradient

  4. Probing the (empirical quantum structure embedded in the periodic table with an effective Bohr model

    Directory of Open Access Journals (Sweden)

    Wellington Nardin Favaro

    2013-01-01

    Full Text Available The atomic shell structure can be observed by inspecting the experimental periodic properties of the Periodic Table. The (quantum shell structure emerges from these properties and in this way quantum mechanics can be explicitly shown considering the (semi-quantitative periodic properties. These periodic properties can be obtained with a simple effective Bohr model. An effective Bohr model with an effective quantum defect (u was considered as a probe in order to show the quantum structure embedded in the Periodic Table. u(Z shows a quasi-smoothed dependence of Z, i.e., u(Z ≈ Z2/5 - 1.

  5. RELATIONSHIP AMONG EVAPORATION FLUX OF GROUNDWATER, DEPTH OF WATER TABLE AND NEGATIVE PRESSURE HEAD IN BARE SOIL

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Evaporation of ground water is a part of moisture circulation in the field.And it is a main natural form in which water transmits from the ground water to the soil water and atmosphere water.According to the simulated experiments, we study the relationship among the evaporation, depth of groundwater table and negative pressure.By theoretical analysis of the experimental results, the main conclusions are drawn as follows.There are two abrupt points in every Q-H curve.The locations of the abrupt points are separately in step with the height of top of the capillary fringe and the height of maximal capillary rise in the soil section.When the depth of ground water table H is small, the evaporation flux of ground water is large.While the depth of water table exceeds the maximal capillary rise of media in vadose zone, the capillary rise breaks up and evaporation flux of groundwater is small.The water content ratio in ground surface tends to be zero and the surface of soil tends to be drought.These conclusions show that the maximal capillary rise of media in vadose zone is an important value in regulating rational depth of ground water to reduce the evaporation of ground water and to increase effective quantity of water resources.In the meantime, these conclusions are of important theoretical and practical significance to reduce the evaporation of ground water, to prevent and cure the salinization of soil, and to make full use of and protect water resources in the northern plains in China.

  6. Application Of Water Table Fluctuation Method To Quantify Spatial Groundwater Recharge Witidn The Southern Slope Of Merapi Volcano, Indonesia

    Directory of Open Access Journals (Sweden)

    Tjahyo Nugroho Adji

    2013-07-01

    that results in groundwater recharge characteristic. The volcanic slope unit (above 600 m as! has the lowest water table fluctuation indicates the resistant comportment to the annual rainfall. Ihis unit is characterized by the relatively high magnitude of recharge of approximately 4270 mm/year.

  7. Interactive plant functional group and water table effects on decomposition and extracellular enzyme activity in Sphagnum peatlands

    Science.gov (United States)

    Magdalena M. Wiedermann; Evan S. Kane; Lynette R. Potvin; Erik A. Lilleskov

    2017-01-01

    Peatland decomposition may be altered by hydrology and plant functional groups (PFGs), but exactly how the latter influences decomposition is unclear, as are potential interactions of these factors.We used a factorial mesocosm experiment with intact 1 m3 peat monoliths to explore how PFGs (sedges vs Ericaceae) and water table level individually...

  8. Key to GHG fluxes from organic soils: site characteristics, agricultural practices or water table management?

    Science.gov (United States)

    Tiemeyer, Bärbel

    2015-04-01

    Drained peatlands are hotspots of greenhouse gas (GHG) emissions. Agriculture is the major land use type for peatlands in Germany and other European countries, but strongly varies in its intensity regarding the groundwater level and the agricultural management. Although the mean annual water table depth is sometimes proposed as an overall predictor for GHG emissions, there is a strong variability of its effects on different peatlands. Furthermore, re-wetting measures generally decrease carbon dioxide emissions, but may strongly increase methane emissions. We synthesized 250 annual GHG budgets for 120 different sites in 13 German peatlands. Carbon dioxide (net ecosystem exchange and ecosystem respiration), nitrous oxide and methane fluxes were measured with transparent and opaque manual chambers. Land management ranged from very intensive use with arable land or grassland with up to five cuts per year to partially or completely re-wetted peatlands. Besides the GHG fluxes, biomass yield, fertilisation, groundwater level, climatic data, vegetation composition and soil properties were measured. Overall, we found a large variability of the total GHG budget ranging from small uptakes to extremely high emissions (> 70 t CO2-equivalents/(ha yr)). At nearly all sites, carbon dioxide was the major component of the GHG budget. Site conditions, especially the nitrogen content of the unsaturated zone and the intra-annual water level distribution, controlled the GHG emissions of the agricultural sites. Although these factors are influenced by natural conditions (peat type, regional hydrology), they could be modified by an improved water management. Agricultural management such as the number of cuts had only a minor influence on the GHG budgets. At the level of individual peatlands, higher water levels always decreased carbon dioxide emissions. In nearly all cases, the trade-off between reduced carbon dioxide and increased methane emissions turned out in favour of the re

  9. LITHOLOGIC CONDITIONS OF THE WATER TABLE LOGGING IN THE AREA OF HAĆKI VILLAGE IN THE BIELSKA PLAIN

    Directory of Open Access Journals (Sweden)

    Krzysztof Micun

    2016-05-01

    Full Text Available The aim of the study was to examine lithological conditions of the water table in the area of Haćki village located in the Bielska Plain. The study involved the measurements of water level in dug wells, hand drill probing to a depth of 5 m, acquiring the samples of water-bearing deposits and analysing their granulation. The results of analyses allowed to calculate the permeability coefficient. The geological structure of the area is dominated by dusty deposits of various origins. Such deposits’ formation directly affects the conditions of filtration and depth of the water table. Groundwater logging near Haćki village in the Bielska Plain appears at a depth of several tens of centimeters to 2 meters in the depressions field and up a little over 5 meters in the case of higher ground surfaces. The presence of perched water was revealed on the hills, periodic leachates at the foot of the hills and scarps and one periodic spring. Water-bearing deposits are medium sands, fine sands and loamy fine sands or fine sands with silt. Consequently, the permeability coefficient is low or even very low. Its values range from 0,001 m·d-1 to 3,8 m·d-1 (d – 24 hours. The widespread presence of dusty deposits in the area affects the limited efficiency of the water table.

  10. "How low can it go?" - Scenarios for the future of water tables and groundwater irrigated agriculture in India

    Science.gov (United States)

    Modi, V.; Fishman, R.

    2010-12-01

    Groundwater irrigation, while critical for food production and rural livelihood in many developing countries, is often unsustainable. India, the world’s largest consumer of groundwater, mostly for irrigation, is a prime example: data suggests water tables are falling in the most of its productive regions. Because of the long-term consequences for the viability and efficiency of agriculture, it is important to know how far water tables might fall and what will eventually stabilize them: will it be a reduction in water use and increases in water use efficiency (a sustainable path) or more pessimistically, an energy ‘crunch’ or the hydrological ‘bottom’. Using national-level data, we document an alarming trend of non-decreasing water withdrawals supported by increasing energy use and little, if any, improvement in efficiency. We also study in detail a particular hot spot of advanced depletion that presents a grave warning signal of how far things can go if allowed to proceed on their present course. In our study area, water tables have been falling rapidly for three decades now and reach as much as 200m, with the astounding consequence that energy use for pumping, subsidized by the state, is now worth more than the income farmers generate from its use. Despite this, the large potential for water savings in agriculture there is still unexploited. We discuss policy measures that can prevent other parts of the country from following the same disastrous trajectory.

  11. Sea level and ground water table depth (WTD): A biogeochemical pacemaker for glacial-interglacial cycling

    Science.gov (United States)

    Cowling, S. A.

    2016-11-01

    The role that changes in sea level have on potential carbon-climate feedbacks are discussed as a potential contributing mechanism for terminating glacial periods. Focus will be on coastal wetlands because these systems can be substantially altered by changing sea level and ground water table depth (WTD); in addition to being important moderators of the exchange of nutrients and energy between terrestrial and marine ecosystems. A hypothesis is outlined that describes how the release of carbon from formerly anaerobic wetland soils and sediments can influence climate when sea levels begin to decline. As ground WTD deepens and eventually recedes from the surface, coastal wetland basins may become isolated from their belowground source of water. With their primary source of base flow removed, coastal wetlands likely dried up, promoting decomposition of the carbon compounds buried in their sediments. Depending on the timing of basin isolation and the timing of decomposition, glacial sea level lows could have triggered a relatively large positive carbon feedback on climate warming, just at the time when a new interglacial period is about to begin.

  12. A simplified model of soakaway infiltration interaction with a shallow groundwater table

    DEFF Research Database (Denmark)

    Roldin, Maria; Locatelli, Luca; Mark, Ole

    2013-01-01

    This paper presents a new and simplified modeling concept for soakaway infiltration in the presence of a shallow groundwater table, including representation of the local groundwater mound and its effects on the infiltration rate. The soil moisture retention curve is used to represent the influence......-dimensional unsaturated/saturated flow model based on Richard’s equation. The comparison shows that soakaway emptying times calculated by the new model are on average 13% higher than the emptying times of the two-dimensional model. The deviation is smaller for scenarios including a shallow groundwater table, only around...... scenarios at all times during the simulation period. The extra uncertainty introduced by this new model is compensated for by the reduction in runtime; it is on average 600 times faster than the two-dimensional model. Furthermore, the new model is based on the same input parameters as the two...

  13. Recharge estimation for transient ground water modeling.

    Science.gov (United States)

    Jyrkama, Mikko I; Sykes, Jon F; Normani, Stefano D

    2002-01-01

    Reliable ground water models require both an accurate physical representation of the system and appropriate boundary conditions. While physical attributes are generally considered static, boundary conditions, such as ground water recharge rates, can be highly variable in both space and time. A practical methodology incorporating the hydrologic model HELP3 in conjunction with a geographic information system was developed to generate a physically based and highly detailed recharge boundary condition for ground water modeling. The approach uses daily precipitation and temperature records in addition to land use/land cover and soils data. The importance of the method in transient ground water modeling is demonstrated by applying it to a MODFLOW modeling study in New Jersey. In addition to improved model calibration, the results from the study clearly indicate the importance of using a physically based and highly detailed recharge boundary condition in ground water quality modeling, where the detailed knowledge of the evolution of the ground water flowpaths is imperative. The simulated water table is within 0.5 m of the observed values using the method, while the water levels can differ by as much as 2 m using uniform recharge conditions. The results also show that the combination of temperature and precipitation plays an important role in the amount and timing of recharge in cooler climates. A sensitivity analysis further reveals that increasing the leaf area index, the evaporative zone depth, or the curve number in the model will result in decreased recharge rates over time, with the curve number having the greatest impact.

  14. The beta-binomial convolution model for 2 × 2 tables with missing cell counts

    NARCIS (Netherlands)

    Eisinga, Rob

    2009-01-01

    This paper considers the beta-binomial convolution model for the analysis of 2×2 tables with missing cell counts.We discuss maximumlikelihood (ML) parameter estimation using the expectation–maximization algorithm and study information loss relative to complete data estimators. We also examine bias o

  15. A Working Model of Natural Selection Illustrated by Table Tennis

    Science.gov (United States)

    Dinc, Muhittin; Kilic, Selda; Aladag, Caner

    2013-01-01

    Natural selection is one of the most important topics in biology and it helps to clarify the variety and complexity of organisms. However, students in almost every stage of education find it difficult to understand the mechanism of natural selection and they can develop misconceptions about it. This article provides an active model of natural…

  16. texreg: Conversion of Statistical Model Output in R to LATEX and HTML Tables

    Directory of Open Access Journals (Sweden)

    Philip Leifeld

    2013-11-01

    Full Text Available A recurrent task in applied statistics is the (mostly manual preparation of model output for inclusion in LATEX, Microsoft Word, or HTML documents usually with more than one model presented in a single table along with several goodness-of-fit statistics. However, statistical models in R have diverse object structures and summary methods, which makes this process cumbersome. This article first develops a set of guidelines for converting statistical model output to LATEX and HTML tables, then assesses to what extent existing packages meet these requirements, and finally presents the texreg package as a solution that meets all of the criteria set out in the beginning. After providing various usage examples, a blueprint for writing custom model extensions is proposed.

  17. Quantification of aerobic biodegradation and volatilization rates of gasoline hydrocarbons near the water table under natural attenuation conditions

    Science.gov (United States)

    Lahvis, M.A.; Baehr, A.L.; Baker, R.J.

    1999-01-01

    Aerobic biodegradation and volatilization near the water table constitute a coupled pathway that contributes significantly to the natural attenuation of hydrocarbons at gasoline spill sites. Rates of hydrocarbon biodegradation and volatilization were quantified by analyzing vapor transport in the unsaturated zone at a gasoline spill site in Beaufort, South Carolina. Aerobic biodegradation rates decreased with distance above the water table, ranging from 0.20 to 1.5g m-3 d-1 for toluene, from 0.24 to 0.38 g m-3 d-1 for xylene, from 0.09 to 0.24 g m-3 d-1 for cyclohexene, from 0.05 to 0.22 g m-3 d-1 for ethylbenzene, and from 0.02 to 0.08 g m-3 d-1 for benzene. Rates were highest in the capillary zone, where 68% of the total hydrocarbon mass that volatilized from the water table was estimated to have been biodegraded. Hydrocarbons were nearly completely degraded within 1 m above the water table. This large loss underscores the importance of aerobic biodegradation in limiting the transport of hydrocarbon vapors in the unsaturated zone and implies that vapor-plume migration to basements and other points of contact may only be significant if a source of free product is present. Furthermore, because transport of the hydrocarbon in the unsaturated zone can be limited relative to that of oxygen and carbon dioxide, soil, gas surveys conducted at hydrocarbon-spill sites would benefit by the inclusion of oxygen- and carbon-dioxide-gas concentration measurements. Aerobic degradation kinetics in the unsaturated zone were approximately first-order. First-order rate constants near the water table were highest for cyctohexene (0.21-0.65 d-1) and nearly equivalent for ethylbenzene (0.11-20.31 d-1), xylenes (0.10-0.31 d-1), toluene (0.09-0.30 d-1), and benzene (0.07,0.31 d-1). Hydrocarbon mass loss rates at the water table resulting from the coupled aerobic biodegradation and volatilization process were determined by extrapolating gas transport rates through the capillary zone. Mass

  18. Numerical Modeling of Table-Top X-Ray Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Shlyaptsev, V N; Dunn, J; Moon, S; Osterheld, A L; Rocca, J J; Detering, F; Rozmus, W; Matte, J P; Fiedorowicz, H; Bartnik, A; Kanouff, M

    2002-04-29

    In this work we report numerical modeling results of laser-generated transient inversion and capillary discharge X-ray lasers. We have found the importance of plasma kinetics approaches in transient X-ray lasers physics by expanding the physical model beyond hydrodynamics approximation. Using Particle and Fokker-Planck codes the clear evidence of the Langdon effect was inferred from the recent experimental data obtained with the Ni-like Pd X-ray laser. In the search for more efficient X-ray lasers we looked closely at alternative target designs utilizing low density targets. In conjunction with recent experiments at LLNL the numerical investigations of gas puff targets has been performed.

  19. Temperature Responses to Infrared-Loading and Water Table Manipulations in Peatland Mesocosms

    Institute of Scientific and Technical Information of China (English)

    Jiquan Chen; Scott Bridgham; Jason Keller; John Pastor; Asko Noormets1and; F. Weltzin

    2008-01-01

    We initiated a multi-factor global change experiment to explore the effects of infrared heat loading (HT) and water table level (WL) treatment on soil temperature (T) in bog and fen peatland mesocosms. We found that the temperature varied highly by year, month, peatland type, soil depth, HT and WL manipulations. The highest effect of HT on the temperature at 25 cm depth was found in June for the bog mesocosms (3.34-4.27℃) but in May for the fen mesocosms (2.32-4.33℃) over the 2-year study period. The effects of WL in the bog mesocosms were only found between August and January, with the wet mesocosms warmer than the dry mesocosms by 0.48-2.03 ℃ over the 2-year study period. In contrast, wetter fen mesocoams were generally cooler by 0.16-3.87℃. Seasonal changes of temperatures elevated by the HT also varied by depth and ecosystem type, with temperature differences at 5 cm and 10 cm depth showing smaller seasonal fluctuations than those at 25 cm and 40 cm in the bog mesocosrns. However, increased HT did not always lead to warmer soil, especially in the fen mesocosms. Both HT and WL manipulations have also changed the length of the non-frozen season.

  20. Effect of Perched Water Tables on Aluminosilicate Stability and Soil Genesis

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The mineral stability and solute activities of soil solution extracted from selected horizons of seven studied pedons of Alfisols in Kentucky, USA, and the relationship between distribution of iron-manganese concretions and the restrictive layers were investigated. The results showed that the genesis and development of these soils and mineral weathering trends were strongly influenced by the depth of bedrock and the presence of perched water tables at lithic (limestone) interfaces due to the dissolution and buffering effect of limestone bedrock. The extractable Mg/Ca ratio as depth function and soil depth above bedrock could be used as indices of weathering and degree of soil development. Maximum iron-manganese concretion accumulation was found to occur in the horizon overlying clay horizon (>40% clay) with a sharp increase in clay content (> 10%), which suggested that zones of Fe-Mn concretion accumulation in soils of the Inner Bluegrass Region appeared to be a sensitive genetic indicator of argillic horizons with restrictive permeability.

  1. Estimating evapotranspiration and groundwater flow from water-table fluctuations for a general wetland scenario

    Science.gov (United States)

    Migration_USER, IPDS; Wiley, Michael J.; Wilcox, Douglas A.

    2016-01-01

    The use of diurnal water-table fluctuation methods to calculate evapotranspiration (ET) and groundwater flow is of increasing interest in ecohydrological studies. Most studies of this type, however, have been located in riparian wetlands of semi-arid regions where groundwater levels are consistently below topographic surface elevations and precipitation events are infrequent. Current methodologies preclude application to a wider variety of wetland systems. In this study, we extended a method for estimating sub-daily ET and groundwater flow rates from water-level fluctuations to fit highly dynamic, non-riparian wetland scenarios. Modifications included (1) varying the specific yield to account for periodic flooded conditions and (2) relating empirically derived ET to estimated potential ET for days when precipitation events masked the diurnal signal. To demonstrate the utility of this method, we estimated ET and groundwater fluxes over two growing seasons (2006–2007) in 15 wetlands within a ridge-and-swale wetland complex of the Laurentian Great Lakes under flooded and non-flooded conditions. Mean daily ET rates for the sites ranged from 4.0 mm d−1 to 6.6 mm d−1. Shallow groundwater discharge rates resulting from evaporative demand ranged from 2.5 mm d−1 to 4.3 mm d−1. This study helps to expand our understanding of the evapotranspirative demand of plants under various hydrologic and climate conditions. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  2. Cervical spine motion in manual versus Jackson table turning methods in a cadaveric global instability model.

    Science.gov (United States)

    DiPaola, Matthew J; DiPaola, Christian P; Conrad, Bryan P; Horodyski, MaryBeth; Del Rossi, Gianluca; Sawers, Andrew; Bloch, David; Rechtine, Glenn R

    2008-06-01

    A study of spine biomechanics in a cadaver model. To quantify motion in multiple axes created by transfer methods from stretcher to operating table in the prone position in a cervical global instability model. Patients with an unstable cervical spine remain at high risk for further secondary injury until their spine is adequately surgically stabilized. Previous studies have revealed that collars have significant, but limited benefit in preventing cervical motion when manually transferring patients. The literature proposes multiple methods of patient transfer, although no one method has been universally adopted. To date, no study has effectively evaluated the relationship between spine motion and various patient transfer methods to an operating room table for prone positioning. A global instability was surgically created at C5-6 in 4 fresh cadavers with no history of spine pathology. All cadavers were tested both with and without a rigid cervical collar in the intact and unstable state. Three headrest permutations were evaluated Mayfield (SM USA Inc), Prone View (Dupaco, Oceanside, CA), and Foam Pillow (OSI, Union City, CA). A trained group of medical staff performed each of 2 transfer methods: the "manual" and the "Jackson table" transfer. The manual technique entailed performing a standard rotation of the supine patient on a stretcher to the prone position on the operating room table with in-line manual cervical stabilization. The "Jackson" technique involved sliding the supine patient to the Jackson table (OSI, Union City, CA) with manual in-line cervical stabilization, securing them to the table, then initiating the table's lock and turn mechanism and rotating them into a prone position. An electromagnetic tracking device captured angular motion between the C5 and C6 vertebral segments. Repeated measures statistical analysis was performed to evaluate the following conditions: collar use (2 levels), headrest (3 levels), and turning technique (2 levels). For all

  3. Steam tables for pure water as an ActiveX component in Visual Basic 6.0

    Science.gov (United States)

    Verma, Mahendra P.

    2003-11-01

    The IAPWS-95 formulation for the thermodynamic properties of pure water was implemented as an ActiveX component ( SteamTables) in Visual Basic 6.0. For input parameters as temperature ( T=190-2000 K) and pressure ( P=3.23×10 -8-10,000 MPa) the program SteamTables calculates the following properties: volume ( V), density ( D), compressibility factor ( Z0), internal energy ( U), enthalpy ( H), Gibbs free energy ( G), Helmholtz free energy ( A), entropy ( S), heat capacity at constant pressure ( Cp), heat capacity at constant volume ( Cv), coefficient of thermal expansion ( CTE), isothermal compressibility ( Ziso), velocity of sound ( VelS), partial derivative of P with T at constant V (d Pd T), partial derivative of T with V at constant P (d Td V), partial derivative of V with P at constant T (d Vd P), Joule-Thomson coefficient ( JTC), isothermal throttling coefficient ( IJTC), viscosity ( Vis), thermal conductivity ( ThrmCond), surface tension ( SurfTen), Prandtl number ( PrdNum) and dielectric constant ( DielCons) for the liquid and vapor phases of pure water. It also calculates T as a function of P (or P as a function of T) along the sublimation, saturation and critical isochor curves, depending on the values of P (or T). The SteamTables can be incorporated in a program in any computer language, which supports object link embedding (OLE) in the Windows environment. An application of SteamTables is illustrated in a program in Visual Basic 6.0 to tabulate the values of the thermodynamic properties of water and vapor. Similarly, four functions, Temperature(Press), Pressure(Temp), State(Temp, Press) and WtrStmTbls(Temp, Press, Nphs, Nprop), where Temp, Press, Nphs and Nprop are temperature, pressure, phase number and property number, respectively, are written in Visual Basic for Applications (VBA) to use the SteamTables in a workbook in MS-Excel.

  4. Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth.

    Science.gov (United States)

    Garrido, Marco; Silva, Paola; Acevedo, Edmundo

    2016-01-01

    Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the "Pampa del Tamarugal", Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ(13)C and δ(18)O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after

  5. Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth

    Science.gov (United States)

    Garrido, Marco; Silva, Paola; Acevedo, Edmundo

    2016-01-01

    Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the “Pampa del Tamarugal”, Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ13C and δ18O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after

  6. Water relations and foliar isotopic composition of Prosopis tamarugo Phil. an endemic tree of the Atacama Desert growing under three levels of water table depth.

    Directory of Open Access Journals (Sweden)

    Marco eGarrido

    2016-03-01

    Full Text Available Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the Pampa del Tamarugal, Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m and 7.1 ± 0.1 m, (the last GWD being our reference were selected and groups of 4 individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and midday water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ13C and δ18O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behaviour and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P

  7. Experimental response of Salix cuttings to sudden water table changing dynamics

    Science.gov (United States)

    Gorla, L.; Signarbieux, C.; Turberg, P.; Buttler, A.; Perona, P.

    2013-12-01

    Hydropower production, agriculture and other human activities change the natural flow regime of rivers, in turn impacting the riparian environment. Inadequate flow rules (e.g., minimal or residual flows) reflecting our limited understanding of eco-hydrological processes have thus been applied since decades. The main challenge for an eco-sustainable water management is to quantify the effects of flow regulation on channel morphodynamics and biological processes. We present a controlled laboratory experiment to investigate riparian vegetation (Salix Viminalis) response to forced water table changing dynamics, from one water regime to another, in a temperate region (Switzerland). Three synthetic flow regimes have been simulated and applied to three batteries of Salix cuttings (60 in total) growing outdoor within plastic pots, each about 1 meter tall. After an initial period where all pots undergone the same oscillations in order to uniform the plants initial conditions, the experiment started, and the water dynamic was changed for two out of three batteries. In particular, one treatment simulated a minimal flow policy, which drastically impacts the low and the medium-low components of the hydrograph, but not the extremes. The other treatment reproduced only the low frequencies corresponding to the seasonal trend of the natural flow regime, still applied on the third battery. Cuttings transitory response dynamics has been quantified by continuous sap flow and water potential measurements, and by regularly collecting growth parameters, as well as leaves photosynthesis, fluorescence, and pictures of each plant. At the end of the experiment, all cuttings were carefully removed and the both above and below ground biomass analyzed in detail. Particularly, the 3D root structure was obtained by High Resolution Computer Tomography. Our analyses reveal a clear dependence between roots distribution and water regime reflecting the need for adaptation, which are also in agreement

  8. An Extended Input Output Table Compiled for Analyzing Water Demand and Consumption at County Level in China

    Directory of Open Access Journals (Sweden)

    Xiangzheng Deng

    2014-05-01

    Full Text Available This paper attempts to propose hybrid methodology of compiling water resource extended input-output (IO table at county level (According to administrative structure of China, a county is subordinate to its province, and provincial level is parallel to state level of other countries. By combining Non-Survey-based RAS-technique for possible iterated results and Partial-Survey-based current situation for actual ongoing resource-consumption, we aimed to depict a more accurate structure for water resource consumption and regional economic impact analysis at a county level in the arid area. Additionally, non-parameter methodology was adopted to interpolate missing data. Since human interventions continually have impacted on the natural environment that would finally lead to over-consumption of natural resources, we introduced water consumption caused by cultivation in the Primary Industry and water usage in other industries into a local input-output matrix of Shandan County in Gansu Province, China. Evidence of empirical analysis shows that the modified IO table can more accurately describe economic structure than weighted provincial average IO table does. Moreover, industrialization is ongoing with economic diversity and continually generating water use demand even though also stimulating imports of light industrial products according to the Partial-Survey reports. It demonstrates that industrialization and increasing household consumption drive a high speed of economic growth but with a high cost of water consumption through the Secondary and Tertiary Industries, even at a far rural area. Hence, water scarcity would be a constraint on sustainable development in regions such as Shandan County when taking economic valuation of natural water consumption into account.

  9. Coupled models of heat transfer and phase transformation for the run-out table in hot rolling

    Institute of Scientific and Technical Information of China (English)

    Shui-xuan CHEN; Jun ZOU; Xin FU

    2008-01-01

    Mathematical models are been proposed to simulate the thermal and metallurgical behaviors of the strip occurring on the run-out table (ROT) in a hot strip mill. A variational method is utilized for the discretization of the governing transient conduction-convection equation, with heat transfer coefficients adaptively determined by the actual mill data. To consider the thermal effect of phase transformation during cooling, a constitutive equation for describing austenite decomposition kinetics of steel in air and water cooling zones is coupled with the heat transfer model. As the basic required inputs in the numerical simulations, thermal material properties are experimentally measured for three carbon steels and the least squares method is used to statistically derive regression models for the properties, including specific heat and thermal conductivity. The numerical simulation and experimental results show that the setup accuracy of the temperature prediction system of ROT is effectively improved.

  10. Using Look-up Tables to Model an Electromagnetic Suspension System

    Directory of Open Access Journals (Sweden)

    Musaab Hassan

    2012-01-01

    Full Text Available Problem statement: The aim of the study was to model an electromagnetic suspension system. The electromagnetic system consists of an electromagnet which was attracted an iron object which was freely suspended in air. Approach: Modelling a magnetic system requires modelling the magnetic force characteristics and the flux characteristics. The force characteristics were to be produced from a nonlinear flux characteristic-current. Results: The modelling of the system was accomplished and simulated using MATLAB/SIMULINK. Conclusion: Using look-up tables proves to give good results in modelling a magnetic suspension system.

  11. Discoloration of polyvinyl chloride (PVC) tape as a proxy for water-table depth in peatlands: validation and assessment of seasonal variability

    Science.gov (United States)

    Booth, Robert K.; Hotchkiss, Sara C.; Wilcox, Douglas A.

    2005-01-01

    Summary: 1. Discoloration of polyvinyl chloride (PVC) tape has been used in peatland ecological and hydrological studies as an inexpensive way to monitor changes in water-table depth and reducing conditions. 2. We investigated the relationship between depth of PVC tape discoloration and measured water-table depth at monthly time steps during the growing season within nine kettle peatlands of northern Wisconsin. Our specific objectives were to: (1) determine if PVC discoloration is an accurate method of inferring water-table depth in Sphagnum-dominated kettle peatlands of the region; (2) assess seasonal variability in the accuracy of the method; and (3) determine if systematic differences in accuracy occurred among microhabitats, PVC tape colour and peatlands. 3. Our results indicated that PVC tape discoloration can be used to describe gradients of water-table depth in kettle peatlands. However, accuracy differed among the peatlands studied, and was systematically biased in early spring and late summer/autumn. Regardless of the month when the tape was installed, the highest elevations of PVC tape discoloration showed the strongest correlation with midsummer (around July) water-table depth and average water-table depth during the growing season. 4. The PVC tape discoloration method should be used cautiously when precise estimates are needed of seasonal changes in the water-table.

  12. Nitrogen Release in Pristine and Drained Peat Profiles in Response to Water Table Fluctuations: A Mesocosm Experiment

    Directory of Open Access Journals (Sweden)

    Merjo P. P. Laine

    2013-01-01

    Full Text Available In the northern hemisphere, variability in hydrological conditions was suggested to increase as a consequence of climate warming, which may result in longer droughts than the area has experienced before. Due to their predominately anoxic conditions, peatlands are expected to respond to changes in hydrological conditions, such as successive drying and rewetting periods. As peatlands are rich in organic matter, any major changes in water table may influence the decomposition of it. The hydrological conditions may also influence release of nutrients from peat profiles as well as affect their transport to downstream ecosystems. In our mesocosm experiment, artificial water table fluctuations in pristine peat profiles caused an increase in dissolved organic nitrogen (DON and ammonium (NH4+-N concentrations, while no response was found in drained peat profiles, although originating from the same peatland complex.

  13. ANAEROBIC CAPACITY MAY NOT BE DETERMINED BY CRITICAL POWER MODEL IN ELITE TABLE TENNIS PLAYERS

    Directory of Open Access Journals (Sweden)

    Alessandro M. Zagatto

    2008-03-01

    Full Text Available The aim of the present study was to verify the applicability of anaerobic work capacity (AWC determined from the critical power model in elite table tennis players. Eight male international level table tennis players participated in the study. The tests undertaken were: 1 A critical frequency test used to determinate the anaerobic work capacity; 2 Wingate tests were performed using leg and arm ergometers. AWC corresponded to 99.5 ± 29.1 table tennis balls. AWC was not related to peak (r = -0.25, mean (r = -0.02, relative peak (r = -0.49 or relative mean power (r = 0.01, nor fatigue index (r = -0.52 (Wingate leg ergometer. Similar correlations for peak (r = -0.34, mean (r = -0.04, relative peak (r = -0.49, relative mean power (r = -0.14 and peak blood lactate concentration (r = -0.08 were determined in the Wingate arm ergometer test. Based on these results the AWC determined by a modified critical power test was not a good index for measurement of anaerobic capacity in table tennis players

  14. Accelerated shallow water modeling

    Science.gov (United States)

    Gandham, Rajesh; Medina, David; Warburton, Timothy

    2015-04-01

    ln this talk we will describe our ongoing developments in accelerated numerical methods for modeling tsunamis, and oceanic fluid flows using two dimensional shallow water model and/or three dimensional incompressible Navier Stokes model discretized with high order discontinuous Galerkin methods. High order discontinuous Galerkin methods can be computationally demanding, requiring extensive computational time to simulate real time events on traditional CPU architectures. However, recent advances in computing architectures and hardware aware algorithms make it possible to reduce simulation time and provide accurate predictions in a timely manner. Hence we tailor these algorithms to take advantage of single instruction multiple data (SIMD) architecture that is seen in modern many core compute devices such as GPUs. We will discuss our unified and extensive many-core programming library OCCA that alleviates the need to completely re-design the solvers to keep up with constantly evolving parallel programming models and hardware architectures. We will present performance results for the flow simulations demonstrating performance leveraging multiple different multi-threading APIs on GPU and CPU targets.

  15. Effects of experimental water table and temperature manipulations on ecosystem CO2 fluxes in an Alaskan rich fen

    Science.gov (United States)

    Chivers, M.R.; Turetsky, M.R.; Waddington, J.M.; Harden, J.W.; McGuire, A.D.

    2009-01-01

    Peatlands store 30% of the world's terrestrial soil carbon (C) and those located at northern latitudes are expected to experience rapid climate warming. We monitored growing season carbon dioxide (CO2) fluxes across a factorial design of in situ water table (control, drought, and flooded plots) and soil warming (control vs. warming via open top chambers) treatments for 2 years in a rich fen located just outside the Bonanza Creek Experimental Forest in interior Alaska. The drought (lowered water table position) treatment was a weak sink or small source of atmospheric CO2 compared to the moderate atmospheric CO2 sink at our control. This change in net ecosystem exchange was due to lower gross primary production and light-saturated photosynthesis rather than increased ecosystem respiration. The flooded (raised water table position) treatment was a greater CO2 sink in 2006 due largely to increased early season gross primary production and higher light-saturated photosynthesis. Although flooding did not have substantial effects on rates of ecosystem respiration, this water table treatment had lower maximum respiration rates and a higher temperature sensitivity of ecosystem respiration than the control plot. Surface soil warming increased both ecosystem respiration and gross primary production by approximately 16% compared to control (ambient temperature) plots, with no net effect on net ecosystem exchange. Results from this rich fen manipulation suggest that fast responses to drought will include reduced ecosystem C storage driven by plant stress, whereas inundation will increase ecosystem C storage by stimulating plant growth. ?? 2009 Springer Science+Business Media, LLC.

  16. Rotating Water Table for the Determination of Non-Steady Forces in a Turbine Stage Through Modified Hydraulic Analogy

    OpenAIRE

    J. S. Rao; E. Raghavacharyulu; Seshadri, V.; V.V.R. Rao

    1983-01-01

    Determination of non-steady forces in a real turbine stage is difficult due to the local flow conditions, for example high pressures, high temperatures and in-accessibility to the region etc. Experimentation in a real turbine is also prohibitive due to the costs involved. An alternate method of arriving at these non-steady forces through the use of modified hydraulic analogy is discussed. A rotating water table facility, developed and fabricated based on the principles of modified hydraulic a...

  17. WATER DIVERSION MODEL

    Energy Technology Data Exchange (ETDEWEB)

    J.B. Case

    1999-12-21

    The distribution of seepage in the proposed repository will be highly variable due in part to variations in the spatial distribution of percolations. The performance of the drip shield and the backfill system may divert the water flux around the waste packages to the invert. Diversion will occur along the drift surface, within the backfill, at the drip shield, and at the Waste Package (WP) surface, even after the drip shield and WP have been breached by corrosion. The purpose and objective of this Analysis and Modeling Report (AMR) are to develop a conceptual model and constitutive properties for bounding the volume and rate of seepage water that flows around the drip shield (CRWMS M&O 1999c). This analysis model is to be compatible with the selected repository conceptual design (Wilkins and Heath, 1999) and will be used to evaluate the performance of the Engineered Barrier System (EBS), and to provide input to the EBS Water Distribution and Removal Model. This model supports the Engineered Barrier System (EBS) postclosure performance assessment for the Site Recommendation (SR). This document characterizes the hydrological constitutive properties of the backfill and invert materials (Section 6.2) and a third material that represents a mixture of the two. These include the Overton Sand which is selected as a backfill (Section 5.2), crushed tuff which is selected as the invert (Section 5.1), and a combined material (Sections 5.9 and 5.10) which has retention and hydraulic conductivity properties intermediate to the selected materials for the backfill and the invert. The properties include the grain size distribution, the dry bulk density and porosity, the moisture retention, the intrinsic permeability, the relative permeability, and the material thermal properties. The van Genuchten relationships with curve fit parameters are used to define the basic retention relationship of moisture potential to volumetric moisture content, and the basic relationship of unsaturated

  18. A Novel Biped Pattern Generator Based on Extended ZMP and Extended Cart-table Model

    Directory of Open Access Journals (Sweden)

    Guangbin Sun

    2015-07-01

    Full Text Available This paper focuses on planning patterns for biped walking on complex terrains. Two problems are solved: ZMP (zero moment point cannot be used on uneven terrain, and the conventional cart-table model does not allow vertical CM (centre of mass motion. For the ZMP definition problem, we propose the extended ZMP (EZMP concept as an extension of ZMP to uneven terrains. It can be used to judge dynamic balance on universal terrains. We achieve a deeper insight into the connection and difference between ZMP and EZMP by adding different constraints. For the model problem, we extend the cart-table model by using a dynamic constraint instead of constant height constraint, which results in a mathematically symmetric set of three equations. In this way, the vertical motion is enabled and the resultant equations are still linear. Based on the extended ZMP concept and extended cart-table model, a biped pattern generator using triple preview controllers is constructed and implemented simultaneously to three dimensions. Using the proposed pattern generator, the Atlas robot is simulated. The simulation results show the robot can walk stably on rather complex terrains by accurately tracking extended ZMP.

  19. A Method to Enhance the Performance of Synthetic Origin-Destination (O-D) Trip Table Estimation Models

    OpenAIRE

    Sivanandan, R.; Nanda, Dhruv

    1998-01-01

    The conventional methods of determining origin-destination (O-D) trip tables involve elaborate surveys, e.g., home interviews, that require considerable time, staff, and funds. To overcome this drawback, a number of theoretical models that synthesize O-D trip tables from link volume data have been developed. The focus of the research reported here was on two of these models The Highway Emulator (THE) and the Linear Programming (LP) model. These models use target/seed tables for guiding the de...

  20. Quality evaluation of commercially sold table water samples in Michael Okpara University of Agriculture, Umudike, Nigeria and surrounding environments

    Directory of Open Access Journals (Sweden)

    D.O. Okorie

    2015-01-01

    Full Text Available In Michael Okpara University of Agriculture, Umudike, Nigeria (MOUAU and surrounding environments, table water of different brands is commercially hawked by vendors. To the best of our knowledge, there is no scientific documentation on the quality of these water samples. Hence this study which evaluated the quality of different brands of water samples commercially sold in MOUAU and surrounding environments. The physicochemical properties (pH, total dissolved solids (TDS, biochemical oxygen demand (BOD, total hardness, dissolved oxygen, Cl, NO3, ammonium nitrogen (NH3N, turbidity, total suspended solids (TSS, Ca, Mg, Na and K of the water samples as indices of their quality were carried out using standard techniques. Results obtained from this study indicated that most of the chemical constituents of these table water samples commercially sold in Umudike environment conformed to the standards given by the Nigerian Industrial Standard (NIS, World Health Organization (WHO and American Public Health Association (APHA, respectively, while values obtained for ammonium nitrogen in these water samples calls for serious checks on methods of their production and delivery to the end users.

  1. The mathematical model of the task of compiling the time-table

    Directory of Open Access Journals (Sweden)

    О.Є. Литвиненко

    2004-01-01

    Full Text Available  The mathematical model of the task of compiling the time-table in High-school has been carried out.  It has been showed, that the task may be reduced to canonical form of extrimal combinatorial tasks with unlinear structure after identical transformations. The algorithm of the task’s decision for realizing the scheme of the directed sorting of variants is indicated.

  2. The mathematical model of the task of compiling the time-table

    OpenAIRE

    Литвиненко, О. Є.; Г.С. Краліна; О.П. Стьопушкіна

    2004-01-01

     The mathematical model of the task of compiling the time-table in High-school has been carried out.  It has been showed, that the task may be reduced to canonical form of extrimal combinatorial tasks with unlinear structure after identical transformations. The algorithm of the task’s decision for realizing the scheme of the directed sorting of variants is indicated.

  3. A Country-Specific Water Consumption Inventory Considering International Trade in Asian Countries Using a Multi-Regional Input-Output Table

    Directory of Open Access Journals (Sweden)

    Yuya Ono

    2017-08-01

    Full Text Available Interest in the impacts of water use in the life cycle of products and services are increasing among various stakeholders. The water footprint is a tool to identify critical and effective points for reducing the impact of water use through the entire life cycle of products, services, and organizations. The purpose of this study was to develop a water consumption inventory database that focused on identifying of Asian water consumption using an input-output (IO framework. An Asia International Input-Output table (AIIO was applied in this study. The amount of water consumption required for agricultural products was estimated by modeling; for other sectors it was estimated from statistical reports. The intensities of direct water consumption in each sector were calculated by dividing the amount of water consumption by the domestic production. Based on the IO analysis using Leontief’s inverse matrix, the intensities of water consumption from cradle to gate were estimated for all goods and services. There was high intensity of water consumption in the primary industry sectors, together with a high dependency on rainwater as an input water source. The water consumption intensities generally showed a larger reduction in secondary sectors, in comparison with the tertiary sectors, due to the use of recycled water. There were differences between this study and previous studies due to the use of site-specific production data and the temporal resolution of crop production. By considering site-specific conditions, it is expected that the dataset developed here can be used for estimating the water footprint of products, services, and organizations in nine countries (Japan, South Korea, China, Taiwan, Thailand, the Philippines, Malaysia, Singapore, Indonesia, and USA.

  4. Generalized Measure of Departure from No Three-Factor Interaction Model for 2 x 2 x K Contingency Tables

    Directory of Open Access Journals (Sweden)

    Yohei Ban

    2008-12-01

    Full Text Available For 2 x 2 x K contingency tables, Tomizawa considered a Shannon entropy type measure to represent the degree of departure from a log-linear model of no three-factor interaction (the NOTFI model. This paper proposes a generalization of Tomizawa's measure for 2 x 2 x K tables. The measure proposed is expressed by using Patil-Taillie diversity index or Cressie-Read power-divergence. A special case of the proposed measure includes Tomizawa's measure. The proposed measure would be useful for comparing the degrees of departure from the NOTFI model in several tables.

  5. Preliminary ECLSS waste water model

    Science.gov (United States)

    Carter, Donald L.; Holder, Donald W., Jr.; Alexander, Kevin; Shaw, R. G.; Hayase, John K.

    1991-01-01

    A preliminary waste water model for input to the Space Station Freedom (SSF) Environmental Control and Life Support System (ECLSS) Water Processor (WP) has been generated for design purposes. Data have been compiled from various ECLSS tests and flight sample analyses. A discussion of the characterization of the waste streams comprising the model is presented, along with a discussion of the waste water model and the rationale for the inclusion of contaminants in their respective concentrations. The major objective is to establish a methodology for the development of a waste water model and to present the current state of that model.

  6. Preliminary ECLSS waste water model

    Science.gov (United States)

    Carter, Donald L.; Holder, Donald W., Jr.; Alexander, Kevin; Shaw, R. G.; Hayase, John K.

    1991-01-01

    A preliminary waste water model for input to the Space Station Freedom (SSF) Environmental Control and Life Support System (ECLSS) Water Processor (WP) has been generated for design purposes. Data have been compiled from various ECLSS tests and flight sample analyses. A discussion of the characterization of the waste streams comprising the model is presented, along with a discussion of the waste water model and the rationale for the inclusion of contaminants in their respective concentrations. The major objective is to establish a methodology for the development of a waste water model and to present the current state of that model.

  7. Extended contingency table: Performance metrics for satellite observations and climate model simulations

    Science.gov (United States)

    AghaKouchak, A.; Mehran, A.

    2013-10-01

    Validation of gridded satellite observations and climate model simulations are fundamental to future improvements in retrieval algorithms and model developments. Among the metrics, the contingency table, which includes a number of categorical indices, is extensively used in evaluation studies. While the categorical indices offer invaluable information, they do not provide any insight into the volume of the variable detected correctly/incorrectly. In this study, the contingency table categorical metrics are extended to volumetric indices for evaluation of gridded data. The suggested indices include (a) Volumetric Hit Index (VHI): volume of correctly detected simulations relative to the volume of the correctly detected simulations and missed observations; (b) Volumetric False Alarm Ratio (VFAR): volume of false simulations relative to the sum of simulations; (c) Volumetric Miss Index (VMI): volume of missed observations relative to the sum of missed observations and correctly detected simulations; and (d) the Volumetric Critical Success Index (VCSI). The latter provides an overall measure of volumetric performance including volumetric hits, false alarms, and misses. First, using two synthetic time series, the volumetric indices are evaluated against the contingency table categorical metrics. Then, the volumetric indices are used to evaluate a gridded data set at the continental scale. The results show that the volumetric indices provide additional information beyond the commonly used categorical metrics that can be useful in evaluating gridded data sets.

  8. Culture of microalgae biomass for valorization of table olive processing water

    Directory of Open Access Journals (Sweden)

    Contreras, C. G.

    2016-09-01

    Full Text Available Table olive processing water (TOPW contains many complex substances, such as phenols, which could be valorized as a substrate for microalgae biomass culture. The aim of this study was to assess the capability of Nannochloropsis gaditana to grow in TOPW at different concentrations (10- 80% in order to valorize this processing water. Within this range, the highest increment of biomass was determined at percentage of 40% of TOPW, reaching an increment of 0.36 ± 0.05 mg volatile suspended solids (VSS/L. Components of algal biomass were similar for the experiments at 10-40% of TOPW, where proteins were the major compounds (56-74%. Total phenols were retained in the microalgae biomass (0.020 ± 0.002 g of total phenols/g VSS. Experiments for 80% of TOPW resulted in a low production of microalgae biomass. High organic matter, nitrogen, phosphorus and phenol removal were achieved in all TOPW concentrations. Although high-value products, such as proteins, were obtained and high removal efficiencies of nutrients were determined, microalgae biomass culture should be enhanced to become a suitable integral processing water treatment.El agua resultante del proceso de elaboración de la aceituna de mesa (TOPW presenta un elevado contenido en sustancias complejas, como fenoles, que podría permitir su uso como sustrato para el cultivo de microalgas. El objetivo de este estudio se centra en evaluar la capacidad de crecimiento de Nannochloropsis gaditana en TOPW a distintas concentraciones (10-80% con vistas a la valorización de estas aguas. El mayor incremento de biomasa se obtuvo para un porcentaje del 40% de TOPW, alcanzando un aumento de 0.36 ± 0.50 mg sólidos en suspensión volátiles (SSV/L. Los componentes presentes en la biomasa han sido similares para los experimentos con 10-40% de TOPW, siendo las proteínas los compuestos mayoritarios en todos los casos (56-74%. Los fenoles totales quedaron retenidos en las microalgas, alcanzando una concentraci

  9. Water accounting for stressed river basins based on water resources management models.

    Science.gov (United States)

    Pedro-Monzonís, María; Solera, Abel; Ferrer, Javier; Andreu, Joaquín; Estrela, Teodoro

    2016-09-15

    Water planning and the Integrated Water Resources Management (IWRM) represent the best way to help decision makers to identify and choose the most adequate alternatives among other possible ones. The System of Environmental-Economic Accounting for Water (SEEA-W) is displayed as a tool for the building of water balances in a river basin, providing a standard approach to achieve comparability of the results between different territories. The target of this paper is to present the building up of a tool that enables the combined use of hydrological models and water resources models to fill in the SEEA-W tables. At every step of the modelling chain, we are capable to build the asset accounts and the physical water supply and use tables according to SEEA-W approach along with an estimation of the water services costs. The case study is the Jucar River Basin District (RBD), located in the eastern part of the Iberian Peninsula in Spain which as in other many Mediterranean basins is currently water-stressed. To guide this work we have used PATRICAL model in combination with AQUATOOL Decision Support System (DSS). The results indicate that for the average year the total use of water in the district amounts to 15,143hm(3)/year, being the Total Water Renewable Water Resources 3909hm(3)/year. On the other hand, the water service costs in Jucar RBD amounts to 1634 million € per year at constant 2012 prices. It is noteworthy that 9% of these costs correspond to non-conventional resources, such as desalinated water, reused water and water transferred from other regions.

  10. The impact of changes in the water table and soil moisture on structural stability of buildings and foundation systems : systematic review CEE10-005 (SR90).

    OpenAIRE

    2012-01-01

    This Systematic Review aims to consider the impact of changes in the ground water table and soil moisture regime on structural stability of buildings and foundation systems. The possible changes in the water table levels and soil moisture conditions are expected as a result of environmental change. Building and infrastructure damage occurs where differential movements exceed the thresholds that the buildings or infrastructure can sustain. At locations where uniform vertical settlement domi...

  11. Significant impacts of irrigation water sources and methods on modeling irrigation effects in the ACME Land Model

    Energy Technology Data Exchange (ETDEWEB)

    Leng, Guoyong; Leung, Lai-Yung; Huang, Maoyi

    2017-07-01

    An irrigation module that considers both irrigation water sources and irrigation methods has been incorporated into the ACME Land Model (ALM). Global numerical experiments were conducted to evaluate the impacts of irrigation water sources and irrigation methods on the simulated irrigation effects. All simulations shared the same irrigation soil moisture target constrained by a global census dataset of irrigation amounts. Irrigation has large impacts on terrestrial water balances especially in regions with extensive irrigation. Such effects depend on the irrigation water sources: surface-water-fed irrigation leads to decreases in runoff and water table depth, while groundwater-fed irrigation increases water table depth, with positive or negative effects on runoff depending on the pumping intensity. Irrigation effects also depend significantly on the irrigation methods. Flood irrigation applies water in large volumes within short durations, resulting in much larger impacts on runoff and water table depth than drip and sprinkler irrigations. Differentiating the irrigation water sources and methods is important not only for representing the distinct pathways of how irrigation influences the terrestrial water balances, but also for estimating irrigation water use efficiency. Specifically, groundwater pumping has lower irrigation water use efficiency due to enhanced recharge rates. Different irrigation methods also affect water use efficiency, with drip irrigation the most efficient followed by sprinkler and flood irrigation. Our results highlight the importance of explicitly accounting for irrigation sources and irrigation methods, which are the least understood and constrained aspects in modeling irrigation water demand, water scarcity and irrigation effects in Earth System Models.

  12. Effect of water-table fluctuations on the degradation of Sphagnum phenols in surficial peats

    Science.gov (United States)

    Abbott, Geoffrey D.; Swain, Eleanor Y.; Muhammad, Aminu B.; Allton, Kathryn; Belyea, Lisa R.; Laing, Christopher G.; Cowie, Greg L.

    2013-04-01

    A much improved understanding of how water-table fluctuations near the surface affect decomposition and preservation of peat-forming plant litter and surficial peats is needed in order to predict possible feedbacks between the peatland carbon cycle and the global climate system. In this study peatland plants (bryophytes and vascular plants), their litter and peat cores were collected from the Ryggmossen peatland in the boreonemoral zone of central Sweden. The extracted insoluble residues from whole plant tissues were depolymerized using thermally assisted hydrolysis and methylation (THM) in the presence of both unlabelled and 13C-labelled tetramethylammonium hydroxide (TMAH) which yielded both vascular plant- and Sphagnum-derived phenols. Methylated 4-isopropenylphenol (IUPAC: 1-methoxy-4-(prop-1-en-2-yl)benzene), methylated cis- and trans-3-(4'-hydroxyphen-1-yl)but-2-enoic acid (IUPAC: (E/Z)-methyl 3-(4-methoxyphenyl)but-2-enoate), and methylated 3-(4'-hydroxyphen-1-yl)but-3-enoic acid (IUPAC: methyl 3-(4-methoxyphenyl)but-3-enoate) (van der Heijden et al., 1997) are confirmed as TMAH thermochemolysis products of "bound" sphagnum acid and also as being specific to Sphagnum mosses. These putative biomarkers were also significant components in the unlabelled TMAH thermochemolysis products from the depolymerization of ultrasonically extracted samples from eight peat cores, one from a hummock and one from a hollow at each of the four stages along the bog plateau-to-swamp forest gradient. We have proposed and measured two parameters namely (i) σ which is defined as the total amount of these four molecules normalised to 100 mg of OC; and (ii) an index (SR%) which is the ratio of σ to the Λ parameter giving a measure of the relative amounts of "bound" sphagnum acid to the "bound" vascular plant phenols in peat moss and the surficial peat layers. Changes in σ and SR% down the bog plateau (BP), bog margin (BM) and fen lagg (FL) cores in the Ryggmossen mire indicates

  13. An investigation of growing season fluctuations of water table in a forestry-drained Scots pine peatland using weather data and spatial information

    Science.gov (United States)

    Hökkä, Hannu; Haahti, Kersti; Sarkkola, Sakari; Nieminen, Mika; Koivusalo, Harri

    2013-04-01

    Soil water table depth (WTD) is one of the most important factors controlling the net primary production such as tree growth on peatlands. The growing season WTD is known to be dependent on the weather conditions, stand evapotranspiration capacity and drainage structures on drained peatlands. In this study we used modeling approach to investigate how meteorological and spatial variables contribute to variation of the growing season WTD in a drained boreal peatland forest. The study data were collected from a Scots pine (Pinus sylvestris L.) dominated experimental peatland stand drained for forestry purposes 70 years ago in Rovaniemi, northern Finland. Double ditching was used to form ca. 0.5 ha artificial catchment in spring 2006. The spacing between 0.9 m deep ditches was 23 m and peat depth varied from 0.6 m to more than 2 m within the area. For monitoring the WTD, 50 perforated plastic tubes were inserted into the peat and spaced in a regular grid to evenly cover the whole catchment area. WTD was manually monitored from each tube at one or two week intervals during the frost free period (early June - end of October) in 2006 - 2009. To account for the hierarchical structure of the data, the linear mixed model technique was applied to construct a prediction model for the logarithm of the WTD in a tube. Meteorological variables were derived from observations of a weather station located 50 km away. The used meteorological variables were the cumulative precipitation, the precipitation of previous 28 days, cumulative evapotranspiration, and the evapotranspiration of previous 30 days. The spatial parameters were the local stand basal area (sum of tree basal areas within 2 m radius around the tube), the distance of a tube to the nearest ditch, and topography (elevation). The meteorological parameters were most important predictors in the model. The distance to a ditch and the elevation were most important spatial parameters. The relationship between the local stand

  14. Modelling water temperature in TOXSWA

    NARCIS (Netherlands)

    Jacobs, C.M.J.; Deneer, J.W.; Adriaanse, P.I.

    2010-01-01

    A reasonably accurate estimate of the water temperature is necessary for a good description of the degradation of plant protection products in water which is used in the surface water model TOXSWA. Based on a consideration of basic physical processes that describe the influence of weather on the

  15. Incision history of Glenwood Canyon, Colorado, USA, from the uranium-series analyses of water-table speleothems

    Directory of Open Access Journals (Sweden)

    Victor J. Polyak

    2013-09-01

    Full Text Available Uranium-series analyses of water-table-type speleothems from Glenwood Cavern and “cavelets” near the town of Glenwood Springs, Colorado, USA, yield incision rates of the Colorado River in Glenwood Canyon for the last ~1.4 My. The incision rates, calculated from dating cave mammillary and cave folia calcite situated 65 and 90 m above the Colorado River, are 174 ± 30 m/My for the last 0.46 My and 144 ± 30 m/My for the last 0.62 My, respectively. These are consistent with incision rates determined from nearby volcanic deposits. In contrast, δ234U model ages (1.39 ± 0.25 My; 1.36 ± 0.25 My; and 1.72 ± 0.25 My from three different samples of mammillary-like subaqueous crust collected from Glenwood Cavern, 375 m above the Colorado River, yield incision rates of 271 +58/-41 m/My, 277 +61/-42 m/ My, and 218 +36/-27 m/My. These data suggest a relatively fast incision rate between roughly 3 and 1 Ma. The onset of Pleistocene glaciation may have influenced this rate by increasing precipitation on the Colorado Plateau starting at 2.5 Ma. Slowing of incision just before 0.6 Ma could be related to the change in frequency of glacial cycles from 40 to 100 kyr in the middle Pleistocene. This interpretation would suggest that the cutting power of the Colorado River prior to 3 Ma was smaller. An alternative interpretation involving tectonic activity would invoke an episode of fast uplift in the Glenwood Canyon region from 3 to 1 Ma.

  16. Spatially variable water table recharge and the hillslope hydrologic response: Analytical solutions to the linearized hillslope Boussinesq equation

    Science.gov (United States)

    Dralle, David N.; Boisramé, Gabrielle F. S.; Thompson, Sally E.

    2014-11-01

    The linearized hillslope Boussinesq equation, introduced by Brutsaert (1994), describes the dynamics of saturated, subsurface flow from hillslopes with shallow, unconfined aquifers. In this paper, we use a new analytical technique to solve the linearized hillslope Boussinesq equation to predict water table dynamics and hillslope discharge to channels. The new solutions extend previous analytical treatments of the linearized hillslope Boussinesq equation to account for the impact of spatiotemporal heterogeneity in water table recharge. The results indicate that the spatial character of recharge may significantly alter both steady state subsurface storage characteristics and the transient hillslope hydrologic response, depending strongly on similarity measures of controls on the subsurface flow dynamics. Additionally, we derive new analytical solutions for the linearized hillslope-storage Boussinesq equation and explore the interaction effects of recharge structure and hillslope morphology on water storage and base flow recession characteristics. A theoretical recession analysis, for example, demonstrates that decreasing the relative amount of downslope recharge has a similar effect as increasing hillslope convergence. In general, the theory suggests that recharge heterogeneity can serve to diminish or enhance the hydrologic impacts of hillslope morphology.

  17. Accurate and fast table look-up models for leakage current analysis in 65 nm CMOS technology

    Institute of Scientific and Technical Information of China (English)

    薛冀颖; 李涛; 余志平

    2009-01-01

    Novel physical models for leakage current analysis in 65 nm technology are proposed. Taking into con-sideration the process variations and emerging effects in nano-scaled technology, the presented models are capable of accurately estimating the subthreshold leakage current and junction tunneling leakage current in 65 nm technol-ogy. Based on the physical models, new table look-up models are developed and first applied to leakage current analysis in pursuit of higher simulation speed. Simulation results show that the novel physical models are in ex-cellent agreement with the data measured from the foundry in the 65 nm process, and the proposed table look-up models can provide great computational efficiency by using suitable interpolation techniques. Compared with the traditional physical-based models, the table look-up models can achieve 2.5X speedup on average on a variety of industry circuits.

  18. Preliminary phenomena identification and ranking tables for simplified boiling water reactor Loss-of-Coolant Accident scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, P.G.; Rohatgi, U.S.; Jo, J.H.; Slovik, G.C.

    1998-04-01

    For three potential Loss-of-Coolant Accident (LOCA) scenarios in the General Electric Simplified Boiling Water Reactors (SBWR) a set of Phenomena Identification and Ranking Tables (PIRT) is presented. The selected LOCA scenarios are typical for the class of small and large breaks generally considered in Safety Analysis Reports. The method used to develop the PIRTs is described. Following is a discussion of the transient scenarios, the PIRTs are presented and discussed in detailed and in summarized form. A procedure for future validation of the PIRTs, to enhance their value, is outlined. 26 refs., 25 figs., 44 tabs.

  19. WTAQ version 2-A computer program for analysis of aquifer tests in confined and water-table aquifers with alternative representations of drainage from the unsaturated zone

    Science.gov (United States)

    Barlow, Paul M.; Moench, Allen F.

    2011-01-01

    The computer program WTAQ simulates axial-symmetric flow to a well pumping from a confined or unconfined (water-table) aquifer. WTAQ calculates dimensionless or dimensional drawdowns that can be used with measured drawdown data from aquifer tests to estimate aquifer hydraulic properties. Version 2 of the program, which is described in this report, provides an alternative analytical representation of drainage to water-table aquifers from the unsaturated zone than that which was available in the initial versions of the code. The revised drainage model explicitly accounts for hydraulic characteristics of the unsaturated zone, specifically, the moisture retention and relative hydraulic conductivity of the soil. The revised program also retains the original conceptualizations of drainage from the unsaturated zone that were available with version 1 of the program to provide alternative approaches to simulate the drainage process. Version 2 of the program includes all other simulation capabilities of the first versions, including partial penetration of the pumped well and of observation wells and piezometers, well-bore storage and skin effects at the pumped well, and delayed drawdown response of observation wells and piezometers.

  20. Water Stress Projection Modeling

    Science.gov (United States)

    2016-09-01

    facility. Stationing analysis done with climate forecasting in mind recognizes an unpredictable future, while striving to best prepare for the...to support additional growth. This attribute places a threshold ca- pacity on water supply and treatment, which may be related to treat- ment plant ...et al. 2013). 3.3 Military impacts reduced water Extreme weather events such as droughts, floods, snow, and ice storms have significant impacts on

  1. Reducing nitrogen leaching losses from paddy field under water-saving irrigation by water table control%控制地下水位减少节水灌溉稻田氮素淋失

    Institute of Scientific and Technical Information of China (English)

    和玉璞; 张展羽; 徐俊增; 杨士红; 洪大林

    2014-01-01

    Effects of controlled drainage (CD) on nitrogen leaching losses from paddy field under controlled irrigation (CI) were investigated. Water table control levels were managing with the use of a lysimeter equipped with an automatic water table control system. Three drainage treatments were implemented, namely, controlled water table 1, controlled water table 2, and controlled water table 3. For controlled water table 1, the water table control levels were adjusted daily based on the actual water table depths that were measured by using a water table observation well. Water table control levels in controlled water table 2 were controlled based on the rice root zone depths in different stages according to the water table management that was tested in the humid regions of Eastern Canada and Midwestern United States. For controlled water table 3, the water table control levels in different stages were selected based on previous studies in paddy field of Southeast China. The water table control levels in the later tillering stage and milk stage were also adjusted depending on the characteristics of rice growth and cultivation needs. Experiments were conducted in nine drainage type lysimeters with a mobile shelter and gallery. Each lysimeter had an area of 2.5 m × 2 m and a depth of 1.3 m. Influence of rainfall was avoided using the mobile shelter to strictly regulate the soil moisture in CI. Each lysimeter was individually irrigated and drained using a pipe installed with a water meter and a tube (40 mm in inner diameter) installed at 1.2 m below the soil surface, respectively. Subsurface drainage was conducted based on the water table control levels by using an automatic water table control system, which was installed on each drain tube in the gallery. Subsurface drainage water were collected twice at 2d intervals after each fertilizer application followed by 4d intervals. A 7d sampling interval was used during the rest time. NH4+–N and NO3−–N concentrations in the

  2. Greenhouse gas emissions of drained fen peatlands in Belarus are controlled by water table, land use, and annual weather conditions

    Science.gov (United States)

    Burlo, Andrei; Minke, Merten; Chuvashova, Hanna; Augustin, Jürgen; Hoffmann, Mathias; Narkevitch, Ivan

    2014-05-01

    Drainage of peatlands causes strong emission of the greenhouse gases (GHG) CO2 and N2O, sometimes combined with a weak CH4 uptake. In Belarus drained peatlands occupy about 1505000 ha or more than 7.2 % of the country area. Joosten (2009) estimates CO2 emission from degraded peatlands in Belarus as 41.3 Mt yr-1 what equals to 47 % of total anthropogenic greenhouse gases (GHGs) emission of country in 2011. However, it could not be checked if these numbers are correct since there are no GHG measurements on these sites up to now. Therefore we studied the GHG emissions with the closed chamber approach in four peatlands situated in central and southern Belarus over a period from August 2010 to August 2012. The measurements comprised eight site types representing different water level conditions, and ranging from grassland and arable land over abandoned fields and peat cuts to near-natural sedge fens. Fluxes of CH4 and N2O were determined using the close-chamber approach every second week in snow free periods and every fourth week during winter time. The annual emissions were calculated based on linear interpolation. Carbon dioxide exchange was measured with transparent and opaque chambers every 3-4 weeks and the annual net ecosystem exchange (NEE) was modeled according to Drösler (2005). Most of the drained sites were sources of CO2 in both years. NEE increased with lower mean annual water table level. The highest NEE value (1263.5 g CO2-C m-1yr-1) was observed at the driest site of the study; an abandoned fen formerly used for agriculture. In contrast, a former peat extraction site with moist peat and small Pinus sylvestris tress were sinks of CO2 with uptake to 389.6 g CO2-C m-1yr-1. The highest N2O emissions were recorded at a drained agricultural fen with mean annual rates of up to 2347 mg N2O-N m-2 yr-1. Significant fluxes of CH4 (15 g CH4C m-2 h-1) were observed only at the near-natural site in the first year of investigation when precipitation and the mean water

  3. Modeling and adaptive motion/force tracking for ver tical wheel on rotating table

    Institute of Scientific and Technical Information of China (English)

    Zhongcai Zhang; Yuqiang Wu; Wei Sun

    2015-01-01

    This paper is devoted to the problem of modeling and adaptive motion/force tracking for a class of nonholonomic dy-namic systems with affine constraints (NDSAC): a vertical wheel on a rotating table. Prior to the development of tracking control er, the dynamic model of the wheel in question is derived in a meticu-lous manner. A continuously differentiable friction model is also considered in the modeling. By exploiting the inherent cascade interconnected structure of the wheel dynamics, an adaptive mo-tion/force tracking control er is presented guaranteeing that the trajectory tracking errors asymptotical y converge to zero while the contact force tracking errors can be made smal enough by tuning design parameters. Simulation results are provided to validate the effectiveness of the proposed tracking methodology.

  4. Stoichiometry, Metabolism and Nutrient Limitation Across the Periodic Table in Natural Flowing-Water Chemostats

    Science.gov (United States)

    Cohen, M. J.; Nifong, R. L.; Kurz, M. J.; Cropper, W. P.; Martin, J. B.

    2014-12-01

    Relative supplies of macro and micronutrients (C,N,P, various metals), along with light and water, controls ecosystem metabolism, trophic energy transfer and community structure. Here we test the hypothesis, using measurements from 41 spring-fed rivers in Florida, that tissue stoichiometry indicates autotroph nutrient limitation status. Low variation in discharge, temperature and chemical composition within springs, but large variation across springs creates an ideal setting to assess the relationship between limitation and resource supply. Molar N:P ranges from 0.4 to 90, subjecting autotrophs to dramatically different nutrient supply. Over this gradient, species-specific autotroph tissue C:N:P ratios are strictly homeostatic, and with no evidence that nutrient supply affects species composition. Expanding to include 19 metals and micronutrients revealed autotrophs are more plastic in response to micronutrient variation, particularly for iron and manganese whose supply fluxes are small compared to biotic demand. Using a Droop model modified to reflect springs conditions (benthic production, light limitation, high hydraulic turnover), we show that tissue stoichiometry transitions from homeostatic to plastic with the onset of nutrient limitation, providing a potentially powerful new tool for predicting nutrient limitation and thus eutrophication in flowing waters.

  5. Flood regime and water table determines tree distribution in a forest-savanna gradient in the Brazilian Pantanal.

    Science.gov (United States)

    Ferreira-Júnior, Walnir G; Schaefer, Carlos E G R; Cunha, Cátia N; Duarte, Temilze G; Chieregatto, Luiz C; Carmo, Flávia M S

    2016-01-01

    This study aimed to recognized the preferential location of species of the tree sinusiae in response to a moisture gradient in Pantanal Matogrossense, Brazil. We established sampling plots of arboreal sinusiae along a soil moisture and flood gradient. Piezometers were installed, allowing monthly measurements of water table depth and flood height during one year. Detrended Correspondence Analysis, Gradient Direct Analysis, Multi-response Permutation Procedures and Indicator Species Analysis were performed to evaluate the effect of moisture gradient on tree distribution. The annual variation of water table is shallower and similar in Seasonally Flooded Forest and Termite Savanna, with increasing depths in Open Savanna, Savanna Forest and Dry Forest. Circa 64% of the species were characterized as having a preferential location in "terrestrial habitats normally not subjected to inundation", while 8% preferentially occur in "wet habitats". Lowest tree richness in flood-affected vegetation types is related to both present-day high climatic seasonality and Late Pleistocene dry paleoclimates in the Pantanal wetland. The tree distribution across different formations in the Pantanal shows a direct relationship with soil moisture gradient.

  6. Growth models and site index table of natural Korean pine forests

    Institute of Scientific and Technical Information of China (English)

    Sun Yuwen; Li Shi; Cui Hong; Li Changsheng; Lju Peng; Zhang Junhua

    1999-01-01

    According to the growth characteristics of natural Korean pine (Pinus Koraiensis) forests, 6 equations such as Chapman-Richards equation, Logistic equation, Power equation, and so on were selected to fit for the growth models for Korean pine forest. The growth models were developed based on 208 random trees and 240 dominant trees. Results show that the Chapman-Richards equation is the best model for estimating tree height by age and DBH, while the Parabola equation is fittest for predicting DBH by age or estimating age from DBH The site index table of Korean pine forest was compiled by using the proportional method with the Chapman-Richards equation as the guide curve and validated by accuracy test.

  7. Relative impacts of key drivers on the response of the water table to a major alley farming experiment

    Directory of Open Access Journals (Sweden)

    A. Ghadouani

    2009-11-01

    Full Text Available Widespread clearing of native vegetation in Southwest Western Australia has led to land degradation associated with rising groundwater, secondary salinisation and waterlogging. Re-establishing deep-rooted perennial vegetation across parts of the landscape is one technique for managing land degradation. Alley farming is an agroforestry practice where multiple perennial tree belts are planted in alternation with traditional agricultural crops. To identify the best configuration (belt width versus alley width for controlling rising groundwater levels and providing viable economic returns, a large scale experiment was established in 1995. The experiment contains seven different alley farming designs, each with transects of piezometers running across tree belts into adjacent alleys to monitor changes in the groundwater level. Two control piezometers were also installed in an adjacent paddock. Groundwater at the site is shallow (<3 m and of poor quality (pH 3–5, Ec 2.1–45.9 mS cm−1 so root water uptake from the saturated zone is limited.

    Simple hydrograph analysis could not separate treatment effects on the water table response. Subsequent statistical analysis revealed that 20–30% of the variability in the water table data over the 12 year study period was attributable to the alley farming experiment. To futher investigate the effect of the experiment on groundwater response, additional hydrograph analysis was conducted to compare the trends in the control piezometers in relation to those located within the belts. A difference of 0.9 m was observed between the mean groundwater levels in the control piezometers and the mean levels in the perennial belt piezometers. For a mean specific yield of 0.03 m3 m−3 (standard deviation of 0.03 m3 m−3 this equates to an additional average annual water use of 27 mm yr−1 (standard deviation of 33 mm yr−1 by the

  8. Interaction of Learner Characteristics with Learning from Three Models of the Periodic Table.

    Science.gov (United States)

    Lehman, Jeffrey R.; And Others

    1984-01-01

    Explored the effects of learning on structural modifications to the periodic table; the location of a periodic table within instructional materials; and the presence of a two-page schema showing relationships between the topics explained in the written materials and the periodic table. Results obtained from 160 students are reported and discussed.…

  9. Interaction of Learner Characteristics with Learning from Three Models of the Periodic Table.

    Science.gov (United States)

    Lehman, Jeffrey R.; And Others

    1984-01-01

    Explored the effects of learning on structural modifications to the periodic table; the location of a periodic table within instructional materials; and the presence of a two-page schema showing relationships between the topics explained in the written materials and the periodic table. Results obtained from 160 students are reported and discussed.…

  10. Effects of a raised water table on greenhouse gas emissions and celery yield from agricultural peat under climate warming conditions

    Science.gov (United States)

    Matysek, Magdalena; Zona, Donatella; Leake, Jonathan; Banwart, Steven

    2017-04-01

    Peatlands are globally important areas for carbon preservation: covering only 3% of world's land, they store 30% of total soil carbon. At the same time, peat soils are widely utilised in agriculture: in Europe 14% of peatland area is under cultivation, 40% of UK peatlands have been drained for agricultural use and 24% of deep peat area in England is being farmed. One of the most important regions for crop production on lowland peats in the UK are the East Anglian Fenlands (the Fens): an area of drained peatlands in East England. 88% of the Fenland area is cultivated, sustaining around 4000 farms and supplying 37% of total vegetable production in England. The soils of the area are fertile (89% of agricultural land being classified as grade 1 or 2) and so crops with high nutritional demands tend to dominate. It is estimated that Fenland peats store 41 Tg of Carbon, which is lost from the ecosystem at a rate of 0.4 Tg C/yr. The Fens are at risk due to continued drainage-induced volume loss of the peat layer via shrinkage, compaction and oxidation, which are estimated to result in wastage rate of 2.1 cm/yr. Cultivation of peat soil requires drainage as most crops are intolerant of root-zone anoxia: this leads to creation of oxic conditions in which organic matter becomes vulnerable to mineralisation by aerobic microorganisms. It is, therefore, crucial to find a water table level which would minimise peat loss and at the same time allow for economically viable crop growth. Despite the importance of preservation of agricultural peats, there is a lack of studies which attempt to find water table level that strikes a balance between crop yield and greenhouse gas production. The future of the Fens is overshadowed by another uncertainty: increases in temperature brought by the climate change. It is estimated that average global temperature increase expected by the end of this century (relative to 1986-2005) would be within the range of 0.3-4.8°C, depending on the scenario

  11. Modeling Water Filtration

    Science.gov (United States)

    Parks, Melissa

    2014-01-01

    Model-eliciting activities (MEAs) are not new to those in engineering or mathematics, but they were new to Melissa Parks. Model-eliciting activities are simulated real-world problems that integrate engineering, mathematical, and scientific thinking as students find solutions for specific scenarios. During this process, students generate solutions…

  12. Modeled ground water age distributions

    Science.gov (United States)

    Woolfenden, Linda R.; Ginn, Timothy R.

    2009-01-01

    The age of ground water in any given sample is a distributed quantity representing distributed provenance (in space and time) of the water. Conventional analysis of tracers such as unstable isotopes or anthropogenic chemical species gives discrete or binary measures of the presence of water of a given age. Modeled ground water age distributions provide a continuous measure of contributions from different recharge sources to aquifers. A numerical solution of the ground water age equation of Ginn (1999) was tested both on a hypothetical simplified one-dimensional flow system and under real world conditions. Results from these simulations yield the first continuous distributions of ground water age using this model. Complete age distributions as a function of one and two space dimensions were obtained from both numerical experiments. Simulations in the test problem produced mean ages that were consistent with the expected value at the end of the model domain for all dispersivity values tested, although the mean ages for the two highest dispersivity values deviated slightly from the expected value. Mean ages in the dispersionless case also were consistent with the expected mean ages throughout the physical model domain. Simulations under real world conditions for three dispersivity values resulted in decreasing mean age with increasing dispersivity. This likely is a consequence of an edge effect. However, simulations for all three dispersivity values tested were mass balanced and stable demonstrating that the solution of the ground water age equation can provide estimates of water mass density distributions over age under real world conditions.

  13. Storm Water Management Model (SWMM)

    Science.gov (United States)

    EPA's Storm Water Management Model (SWMM) is used throughout the world for planning, analysis and design related to stormwater runoff, combined and sanitary sewers, and other drainage systems in urban areas.

  14. Modelling Ballast Water Transport

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, S.; Babu, M.T.; Vethamony, P.

    by toolbox, available in MIKE software, by predicting the water elevation using the four major constituents M2, S2, K1 and O1 at the coastal tidal stations Okha and Godia (International Hydrographic Bureau, Spec. Pub, Monaco). Subsequently the tidal...-gulf is the highest compared to that on the northern and southern coasts. References Panvelkar, J.S., Bendre, V.M. and A.S.Barve (1986). ?Software for harmonic and spectral analysis of tidal data?, Proc. 3rd Indian Conference on ocean engineering, IIT Bombay, Dec...

  15. Table of 3D organ model IDs and organ names (IS-A Tree) - BodyParts3D | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available List Contact us BodyParts3D Table of 3D organ model IDs and organ names (IS-A Tree) Data detail Data name Table of 3D organ model...ontents List of downloadable 3D organ models in a tab-delimited text file format, describing the correspondence between 3D organ mode...| Contact Us Table of 3D organ model IDs and organ names (IS-A Tree) - BodyParts3D | LSDB Archive ...

  16. Integrating Techniques to Understand the Biological Controls on Redox Conditions at Water Table Interfaces in the Subsurface

    Science.gov (United States)

    Voytek, M. A.; Cozzarelli, I. M.; Kirshtein, J. D.; Bohlke, J.

    2006-05-01

    The Norman Oklahoma Landfill is a closed, unlined municipal landfill in the alluvium of the Canadian River with a leachate plume that extends at least 225m downgradient. The fate and transport of chemical species in the subsurface of this system is largely controlled by changes in the reduction-oxidation (redox) potential which are driven by hydrology, chemistry and microbiology. In this study, we focused on the microbiological and geochemical factors that control redox conditions at the mixing interface of recharge water and aquifer/plume water at two sites (a background site where the contaminant plume rarely reaches the water table and a contaminated site where the plume routinely mixes with recharge water). We examined denitrification, nitrification, iron reduction, sulfate reduction, and methanogenesis using standard microbiological, molecular and geochemical approaches to quantify these processes. Multilevel wells were sampled for geochemistry and core material was collected at the same locations for microbial analyses. The distribution and abundance of specific microbial guilds were determined using Most Probable Number (MPN) analysis and quantitative PCR (qPCR). In general, we see evidence of enhanced microbial activity (i.e. microbially mediated chemical transformations) and microbial abundance at the interfaces due to the increase in oxidized electron acceptors as well as dissolved organic carbon availability from the landfill leachate. For example, water ammonia concentrations decrease near the water table possibly due to nitrification, when ammonium rich leachate water comes into contact with oxygenated recharge. The oxidation of ammonium by nitrification to nitrate is supported by the observation of an increase in nitrogen isotope fractionation resulting in increasing delta-15N values which also correspond to an increase in the abundance of nitrifying bacteria. Based on profiles of the geochemistry and abundance and distribution of specific microbial

  17. Effect of ground-water recharge on configuration of the water table beneath sand dunes and on seepage in lakes in the sandhills of Nebraska, U.S.A.

    Science.gov (United States)

    Winter, T.C.

    1986-01-01

    Analysis of water-level fluctuations in about 30 observation wells and 5 lakes in the Crescent Lake National Wildlife Refuge in the sandhills of Nebraska indicates water-table configuration beneath sand dunes in this area varies considerably, depending on the configuration of the topography of the dunes. If the topography of an interlake dunal area is hummocky, ground-water recharge is focused at topographic lows causing formation of water-table mounds. These mounds prevent ground-water movement from topographically high lakes to adjacent lower lakes. If a dune ridge is sharp, the opportunity for focused recharge does not exist, resulting in water-table troughs between lakes. Lakes aligned in descending altitudes, parallel to the principal direction of regional ground-water movement, generally have seepage from higher lakes toward lower lakes. ?? 1986.

  18. Water table response to an experimental alley farming trial: dissecting the spatial and temporal structure of the data.

    Science.gov (United States)

    Noorduijn, S L; Ghadouani, A; Vogwill, R; Smettem, K R J; Legendre, P

    2010-09-01

    Clearing vegetation for traditional agriculture diminishes native habitat and reduces plant transpiration, leading to increased groundwater recharge and onset of dryland salinization due to rising groundwater and mobilization of salt stores in the soil profile. This change in hydrology and salinity can also negatively affect biodiversity in many semiarid regions. Alternating native perennial tree belts with mono-species agriculture within the tree belt alleys is one possible system that can provide recharge control and recover some of the ecosystem services of degraded agricultural landscapes. To assess the effect of this agroforestry technique on groundwater levels, an alley farming trial was established in 1995, incorporating different combinations of belt width, alley width, and revegetation density. Transects of piezometers within each design have been monitored from October 1995 to January 2008. The data set consisted of 70 piezometers monitored on 39 dates. Two trends were observed within the raw data: An increase in water table depth with time and an increase in the range of depths monitored at the site were clearly discernible. However, simple hydrograph analysis of the data has proved unsuccessful at distinguishing the effect of the tree belts on the water table morphology. The statistical techniques employed in this paper to show the effect of the experiment on the water table were variation partitioning, principal coordinates of neighbor matrices (PCNM), and canonical redundancy analysis (RDA). The environmental variables (alley farming design, distance of piezometer from the tree belt, and percentage vegetation cover including edge effect) explained 20-30% of the variation of the transformed and detrended data for the entire site. The spatial PCNM variables explained a further 20-30% of the variation. Partitioning of the site into a northern and southern block increased the proportion of explained variation for the plots in the northern block. The

  19. 2002 Water-Table Contours of the Mojave River and the Morongo Ground-Water Basins, San Bernardino County, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Mojave River and Morongo ground-water basins are in the southwestern part of the Mojave Desert in southern California. Ground water from these basins supplies a...

  20. River water quality modelling: II

    DEFF Research Database (Denmark)

    Shanahan, P.; Henze, Mogens; Koncsos, L.

    1998-01-01

    The U.S. EPA QUAL2E model is currently the standard for river water quality modelling. While QUAL2E is adequate for the regulatory situation for which it was developed (the U.S. wasteload allocation process), there is a need for a more comprehensive framework for research and teaching. Moreover......, and to achieve robust model calibration. Mass balance problems arise from failure to account for mass in the sediment as well as in the water column and due to the fundamental imprecision of BOD as a state variable. (C) 1998 IAWQ Published by Elsevier Science Ltd. All rights reserved....

  1. Relative impacts of key drivers on the response of the water table to a major alley farming experiment

    Science.gov (United States)

    Noorduijn, S. L.; Smettem, K. R. J.; Vogwill, R.; Ghadouani, A.

    2009-11-01

    Widespread clearing of native vegetation in Southwest Western Australia has led to land degradation associated with rising groundwater, secondary salinisation and waterlogging. Re-establishing deep-rooted perennial vegetation across parts of the landscape is one technique for managing land degradation. Alley farming is an agroforestry practice where multiple perennial tree belts are planted in alternation with traditional agricultural crops. To identify the best configuration (belt width versus alley width) for controlling rising groundwater levels and providing viable economic returns, a large scale experiment was established in 1995. The experiment contains seven different alley farming designs, each with transects of piezometers running across tree belts into adjacent alleys to monitor changes in the groundwater level. Two control piezometers were also installed in an adjacent paddock. Groundwater at the site is shallow (agroforestry system. It is concluded that declining annual rainfall is the principal control on hydrograph response at the site, whilst perennial biomass development has a lesser impact on water table depth.

  2. Table-top water-window soft X-ray microscope using a Z-pinching capillary discharge source

    Science.gov (United States)

    Nawaz, M. F.; Nevrkla, M.; Jancarek, A.; Torrisi, A.; Parkman, T.; Turnova, J.; Stolcova, L.; Vrbova, M.; Limpouch, J.; Pina, L.; Wachulak, P.

    2016-07-01

    The development and demonstration of a table-top transmission soft X-ray (SXR) microscope, using a laboratory incoherent capillary discharge source has been carried out. This Z-pinching capillary discharge water-window SXR source, is a first of its kind to be used for high spatial resolution microscopy at λ = 2.88 nm (430 eV) . A grazing incidence ellipsoidal condenser mirror is used for focusing of the SXR radiation at the sample plane. The Fresnel zone plate objective lens is used for imaging of the sample onto a back-illuminated (BI) CCD camera. The achieved half-pitch spatial resolution of the microscope approaches 100 nm, as demonstrated by the knife-edge test. Details about the source, and the construction of the microscope are presented and discussed. Additionally, the SXR images of various samples, proving applicability of such microscope for observation of objects in the nanoscale, are shown.

  3. Mortality table construction

    Science.gov (United States)

    Sutawanir

    2015-12-01

    Mortality tables play important role in actuarial studies such as life annuities, premium determination, premium reserve, valuation pension plan, pension funding. Some known mortality tables are CSO mortality table, Indonesian Mortality Table, Bowers mortality table, Japan Mortality table. For actuary applications some tables are constructed with different environment such as single decrement, double decrement, and multiple decrement. There exist two approaches in mortality table construction : mathematics approach and statistical approach. Distribution model and estimation theory are the statistical concepts that are used in mortality table construction. This article aims to discuss the statistical approach in mortality table construction. The distributional assumptions are uniform death distribution (UDD) and constant force (exponential). Moment estimation and maximum likelihood are used to estimate the mortality parameter. Moment estimation methods are easier to manipulate compared to maximum likelihood estimation (mle). However, the complete mortality data are not used in moment estimation method. Maximum likelihood exploited all available information in mortality estimation. Some mle equations are complicated and solved using numerical methods. The article focus on single decrement estimation using moment and maximum likelihood estimation. Some extension to double decrement will introduced. Simple dataset will be used to illustrated the mortality estimation, and mortality table.

  4. Soil CO2 efflux in a degraded raised bog is regulated by water table depth rather than recent plant assimilate

    Directory of Open Access Journals (Sweden)

    U.H. Kritzler

    2016-02-01

    Full Text Available Understanding the climatic and biological factors that regulate soil carbon dioxide (CO2 efflux is crucial in peatlands because they contain a large proportion of terrestrial carbon (C. We predicted that rainfall reduction would increase soil CO2 efflux, and that cessation of below-ground allocation of recent plant assimilate would reduce soil CO2 efflux. These predictions were tested in the field using rainfall shelters that allowed a maximum of 40 % of rainfall onto 2 × 2 m plots by diverting rainwater from the shelter roofs with guttering, and by girdling stems of the dominant plant, Calluna vulgaris, for two years. We also used 13CO2-pulse labelling of intact monoliths at ambient CO2 concentrations to trace recent assimilate from plant shoots to roots, bulk soil, leachate, dissolved organic carbon (DOC and soil CO2 efflux . Soil CO2 efflux in the sheltered plots increased in Year 1 but not in Year 2, and we found a positive relationship between soil CO2 efflux and water table depth. Our data indicate that lowering the water table below a critical threshold (15–20 cm affects soil CO2 efflux. Girdling of C. vulgaris shoots resulted in no measurable reduction in soil CO2 efflux, while only ~3 % of 13C fixed by shoots was recovered in soil CO2 efflux and DOC in the 20 days after labelling. Our findings show that below-ground allocation of recent assimilate from C. vulgaris plants > 6 years old has little impact on soil CO2 efflux.

  5. Round table part 3 : Identification of the key technologies and collaboration for water recycling

    Science.gov (United States)

    Lasseur, Christophe; Tikhomirov, Alexander A.; Wheeler, Raymond

    2016-07-01

    The first metabolic needs in terms of mass is water. Among the years a large number of studies have been performed to recover condensate as well as from urine. Production of water is as well considered and demonstrated via Sabatier reactor. Within this part 3 of the roundtable it is proposed to perform a state of the art of the main activities in the world and to identify overlap and synergies. Recommendation for potential collaboration or exchanges will be discussed.

  6. Modeling water waves beyond perturbations

    CERN Document Server

    Clamond, Didier

    2015-01-01

    In this chapter, we illustrate the advantage of variational principles for modeling water waves from an elementary practical viewpoint. The method is based on a `relaxed' variational principle, i.e., on a Lagrangian involving as many variables as possible, and imposing some suitable subordinate constraints. This approach allows the construction of approximations without necessarily relying on a small parameter. This is illustrated via simple examples, namely the Serre equations in shallow water, a generalization of the Klein-Gordon equation in deep water and how to unify these equations in arbitrary depth. The chapter ends with a discussion and caution on how this approach should be used in practice.

  7. CHEMICAL REACTIONS SIMULATED BY GROUND-WATER-QUALITY MODELS.

    Science.gov (United States)

    Grove, David B.; Stollenwerk, Kenneth G.

    1987-01-01

    Recent literature concerning the modeling of chemical reactions during transport in ground water is examined with emphasis on sorption reactions. The theory of transport and reactions in porous media has been well documented. Numerous equations have been developed from this theory, to provide both continuous and sequential or multistep models, with the water phase considered for both mobile and immobile phases. Chemical reactions can be either equilibrium or non-equilibrium, and can be quantified in linear or non-linear mathematical forms. Non-equilibrium reactions can be separated into kinetic and diffusional rate-limiting mechanisms. Solutions to the equations are available by either analytical expressions or numerical techniques. Saturated and unsaturated batch, column, and field studies are discussed with one-dimensional, laboratory-column experiments predominating. A summary table is presented that references the various kinds of models studied and their applications in predicting chemical concentrations in ground waters.

  8. Water Tables, Evapotranspiration, and Climate Variability: A Decade of Observations From a Semi-Arid Riparian Ecosystem

    Science.gov (United States)

    Thibault, J. R.; Cleverly, J. R.; Dahm, C.

    2009-12-01

    Native (Rio Grande cottonwood) riparian ecosystems in the semi-arid Rio Grande floodplain of central New Mexico are threatened by hydrologic alterations and highly competitive invasive vegetation (saltcedar, Russian olive). Climate change is expected to alter surface runoff in the southwestern United States and exacerbate water scarcity. Depletions are likely to increase in this agricultural riverine corridor downstream of the rapidly growing Albuquerque metropolitan area. Long-term monitoring of shallow alluvial water tables (WTs) and evapotranspiration (ET) in native, non-native, and mixed communities along the river has provided critical information to help understand how water availability affects these ecosystems during a decade of extreme climate variability. Here, we present several observations, with implications for restoration. WTs ranged from several meters depth to flood stage and from relatively stable to highly dynamic, which can influence recruitment of native vegetation and ecosystem functioning. Annual ET declined with deeper WTs across sites, with robust correlations where WTs were dynamic. Riparian communities responded differently to drought cycles and to restorative flooding during peak runoff at the onset of the growing season. Annual ET in a native-dominated system was reduced following removal of non-native understory vegetation, but returned to previous levels when regrowth was left unmanaged. Long-term data are valuable assets that can help optimize efforts to sustain and restore native ecosystems amid the challenges of a changing climate.

  9. Analysis of contingency tables based on generalised median polish with power transformations and non-additive models.

    Science.gov (United States)

    Klawonn, Frank; Jayaram, Balasubramaniam; Crull, Katja; Kukita, Akiko; Pessler, Frank

    2013-01-01

    Contingency tables are a very common basis for the investigation of effects of different treatments or influences on a disease or the health state of patients. Many journals put a strong emphasis on p-values to support the validity of results. Therefore, even small contingency tables are analysed by techniques like t-test or ANOVA. Both these concepts are based on normality assumptions for the underlying data. For larger data sets, this assumption is not so critical, since the underlying statistics are based on sums of (independent) random variables which can be assumed to follow approximately a normal distribution, at least for a larger number of summands. But for smaller data sets, the normality assumption can often not be justified. Robust methods like the Wilcoxon-Mann-Whitney-U test or the Kruskal-Wallis test do not lead to statistically significant p-values for small samples. Median polish is a robust alternative to analyse contingency tables providing much more insight than just a p-value. Median polish is a technique that provides more information than just a p-value. It explains the contingency table in terms of an overall effect, row and columns effects and residuals. The underlying model for median polish is an additive model which is sometimes too restrictive. In this paper, we propose two related approach to generalise median polish. A power transformation can be applied to the values in the table, so that better results for median polish can be achieved. We propose a graphical method how to find a suitable power transformation. If the original data should be preserved, one can apply other transformations - based on so-called additive generators - that have an inverse transformation. In this way, median polish can be applied to the original data, but based on a non-additive model. The non-linearity of such a model can also be visualised to better understand the joint effects of rows and columns in a contingency table.

  10. A diagnosis of sub-surface water table dynamics in low hydraulic conductivity soils in the sugar cane fields of Pongola, South Africa

    Science.gov (United States)

    Malota, Mphatso; Senzanje, Aidan

    2016-04-01

    Water and land are the two natural resources restraining crop production in South Africa. With the increasing demand for food, emphasis has shifted from the sole reliance on rain fed crop production, to irrigation. The deterioration in irrigation water quality from surface water sources is, however, posing a big challenge to the sustainability of irrigated crop production. This is because more water is required for leaching, resulting in shallow water tables in agricultural lands. The installation of well designed subsurface drainage systems alone is not enough; the provision of timely maintenance is also necessary. In this study, the extent and severity of problems as a consequence of shallow water tables and their possible causes were investigated at three sugarcane fields in Pongola, South Africa, having low hydraulic conductivity soils. Also investigated were soil salinity levels and the temporal variation in the salinity of the irrigation water. A water table map of a 32 ha sugarcane field was generated, using observed water table depth (WTD) data from 36 piezometers monitored from September 2011 to February 2012. Out of the total 32 ha under cultivation, 12% was found to be affected by shallow WTDs of less than the 1.0 m design WTD. The inability of natural drainage to cope with subsurface drainage needs and the poor maintenance of subsurface drainage systems contributed to the shallow water tables in the area. Furthermore, the currently adopted drainage design criteria also proved unsatisfactory with mean observed water table depth and drainage discharge (DD) of 20% and 50%, respectively, less than their respective design levels. The salinity of the irrigation water was, on average, 32% higher than threshold tolerance level of sugarcane. The root zone soil salinity levels at the three study sites were greater than the 1.7 dS m-1 threshold for sugar cane. The subsurface drainage design criteria adopted at the site needs to be revisited by ensuring that the

  11. Water Distribution and Removal Model

    Energy Technology Data Exchange (ETDEWEB)

    Y. Deng; N. Chipman; E.L. Hardin

    2005-08-26

    The design of the Yucca Mountain high level radioactive waste repository depends on the performance of the engineered barrier system (EBS). To support the total system performance assessment (TSPA), the Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is developed to describe the thermal, mechanical, chemical, hydrological, biological, and radionuclide transport processes within the emplacement drifts, which includes the following major analysis/model reports (AMRs): (1) EBS Water Distribution and Removal (WD&R) Model; (2) EBS Physical and Chemical Environment (P&CE) Model; (3) EBS Radionuclide Transport (EBS RNT) Model; and (4) EBS Multiscale Thermohydrologic (TH) Model. Technical information, including data, analyses, models, software, and supporting documents will be provided to defend the applicability of these models for their intended purpose of evaluating the postclosure performance of the Yucca Mountain repository system. The WD&R model ARM is important to the site recommendation. Water distribution and removal represents one component of the overall EBS. Under some conditions, liquid water will seep into emplacement drifts through fractures in the host rock and move generally downward, potentially contacting waste packages. After waste packages are breached by corrosion, some of this seepage water will contact the waste, dissolve or suspend radionuclides, and ultimately carry radionuclides through the EBS to the near-field host rock. Lateral diversion of liquid water within the drift will occur at the inner drift surface, and more significantly from the operation of engineered structures such as drip shields and the outer surface of waste packages. If most of the seepage flux can be diverted laterally and removed from the drifts before contacting the wastes, the release of radionuclides from the EBS can be controlled, resulting in a proportional reduction in dose release at the accessible environment. The purposes

  12. Map Plant Communities & Influence of Annual Water Table Fluctuations on Successional Expression: Malheur NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The 2012 Malheur NWR CCP identified the development of an ecological succession model (State-and-Transition Model, or STM) as a high priority for understanding how...

  13. Longevity of acid discharges from underground mines located above the regional water table.

    Science.gov (United States)

    Demchak, J; Skousen, J; McDonald, L M

    2004-01-01

    The duration of acid mine drainage flowing out of underground mines is important in the design of watershed restoration and abandoned mine land reclamation projects. Past studies have reported that acid water flows from underground mines for hundreds of years with little change, while others state that poor drainage quality may last only 20 to 40 years. More than 150 above-drainage (those not flooded after abandonment) underground mine discharges from Pittsburgh and Upper Freeport coal seams were located and sampled during 1968 in northern West Virginia, and we revisited 44 of those sites in 1999-2000 and measured water flow, pH, acidity, Fe, sulfate, and conductivity. We found no significant difference in flows between 1968 and 1999-2000. Therefore, we felt the water quality data could be compared and the data represented real changes in pollutant concentrations. There were significant water quality differences between year and coal seam, but no effect of disturbance. While pH was not significantly improved, average total acidity declined 79% between 1968 and 1999-2000 in Pittsburgh mines (from 66.8 to 14 mmol H+ L(-1)) and 56% in Upper Freeport mines (from 23.8 to 10.4 mmol H+ L(-1)). Iron decreased an average of about 80% across all sites (from an average of 400 to 72 mg L(-1)), while sulfate decreased between 50 and 75%. Pittsburgh seam discharge water was much worse in 1968 than Upper Freeport seam water. Twenty of our 44 sites had water quality information in 1980, which served as a midpoint to assess the slope of the decline in acidity and metal concentrations. Five of 20 sites (25%) showed an apparent exponential rate of decline in acidity and iron, while 10 of 20 sites (50%) showed a more linear decline. Drainage from five Upper Freeport sites increased in acidity and iron. While it is clear that surface mines and below-drainage underground mines improve in discharge quality relatively rapidly (20-40 years), above-drainage underground mines are not as

  14. Table Manners

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Good table manners are more than about proper eating,it’s about being kind and considerate of others.Although table manners are different from country to country,they still share some similarities both in good and bad table manners.

  15. Environmental Monitoring, Water Quality - MO 2009 Water Quality Standards - Table G Lake Classifications and Use Designations (SHP)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This data set contains Missouri Water Quality Standards (WQS) lake classifications and use designations described in the Missouri Code of State Regulations (CSR), 10...

  16. Water Table Management Reduces Tile Nitrate Loss in Continuous Corn and in a Soybean-Corn Rotation

    Directory of Open Access Journals (Sweden)

    Craig F. Drury

    2001-01-01

    Full Text Available Water table management systems can be designed to alleviate soil water excesses and deficits, as well as reduce nitrate leaching losses in tile discharge. With this in mind, a standard tile drainage (DR system was compared over 8 years (1991 to 1999 to a controlled tile drainage/subirrigation (CDS system on a low-slope (0.05 to 0.1% Brookston clay loam soil (Typic Argiaquoll in southwestern Ontario, Canada. In the CDS system, tile discharge was controlled to prevent excessive drainage, and water was pumped back up the tile lines (subirrigation to replenish the crop root zone during water deficit periods. In the first phase of the study (1991 to 1994, continuous corn (Zea mays, L. was grown with annual nitrogen (N fertilizer inputs as per local soil test recommendations. In the second phase (1995 to 1999, a soybean (Glycine max L., Merr.-corn rotation was used with N fertilizer added only during the two corn years. In Phase 1 when continuous corn was grown, CDS reduced total tile discharge by 26% and total nitrate loss in tile discharge by 55%, compared to DR. In addition, the 4-year flow weighted mean (FWM nitrate concentration in tile discharge exceeded the Canadian drinking water guideline (10 mg N l–1 under DR (11.4 mg N l–1, but not under CDS (7.0 mg N l–1. In Phase 2 during the soybean-corn rotation, CDS reduced total tile discharge by 38% and total nitrate loss in tile discharge by 66%, relative to DR. The 4-year FWM nitrate concentration during Phase 2 in tile discharge was below the drinking water guideline for both DR (7.3 mg N l–1 and CDS (4.0 mg N l–1. During both phases of the experiment, the CDS treatment caused only minor increases in nitrate loss in surface runoff relative to DR. Hence CDS decreased FWM nitrate concentrations, total drainage water loss, and total nitrate loss in tile discharge relative to DR. In addition, soybean-corn rotation reduced FWM nitrate concentrations and total nitrate loss in tile discharge

  17. 40 CFR Table 6 to Subpart Bbbb of... - Model Rule-Requirements for Validating Continuous Emission Monitoring Systems (CEMS)

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Model Rule-Requirements for Validating Continuous Emission Monitoring Systems (CEMS) 6 Table 6 to Subpart BBBB of Part 60 Protection of Environment...—Requirements for Validating Continuous Emission Monitoring Systems (CEMS) For the following continuous...

  18. 40 CFR Table 4 to Subpart Ffff of... - Model Rule-Requirements for Continuous Emission Monitoring Systems (CEMS)

    Science.gov (United States)

    2010-07-01

    ... Emission Monitoring Systems (CEMS) 4 Table 4 to Subpart FFFF of Part 60 Protection of Environment...—Model Rule—Requirements for Continuous Emission Monitoring Systems (CEMS) As stated in § 60.3039, you... CEMS Use the following performance specifications (P.S.) in appendix B of this part for your CEMS...

  19. Mobility and transport of mercury and methylmercury in peat as a function of changes in water table regime and plant functional groups

    Science.gov (United States)

    Kristine M. Haynes; Evan S. Kane; Lynette Potvin; Erik A. Lilleskov; Randy Kolka; Carl P. J. Mitchell

    2017-01-01

    Climate change is likely to significantly affect the hydrology, ecology, and ecosystem function of peatlands, with potentially important but unclear impacts on mercury mobility within and transport from peatlands. Using a full-factorial mesocosm approach, we investigated the potential impacts on mercury mobility of water table regime changes (high and low) and...

  20. Natural attenuation of copper in the water table aquifer below an industrial site

    Science.gov (United States)

    Kedziorek, M. A.

    2003-12-01

    The contamination of soils and aquifers by inorganic pollutants is so extensive in industrial sites that it hardly seems economically feasible to decontaminate the large areas or soil volumes involved. It is therefore worthwhile to investigate whether the local environment is capable of attenuating contamination. Natural attenuation by degradation seems realistic for many organic pollutants. We show that it can also occur for inorganic pollutants. The phreatic-fill aquifer underlying an industrial plant located on the banks of the Garonne River (Southwestern France) is contaminated by acidic water (pH down to 1) and high concentrations of sulfate (up to 50 g/L) and copper (up to 30 g/L). As acidic water, rich in Cu and sulfate, moves away from the contamination source, pH increases due to buffering of aquifer solids, dissolved Cu concentrations decrease by 6 orders of magnitude, while sulfate concentrations decrease little. The Cu disappearing from the water phase is found as solid in cores in the area of the site where pH increases to 5-6.

  1. Fractal water quality fluctuations spanning the periodic table in an intensively farmed watershed.

    Science.gov (United States)

    Aubert, Alice H; Kirchner, James W; Gascuel-Odoux, Chantal; Faucheux, Mikael; Gruau, Gérard; Mérot, Philippe

    2014-01-21

    Recently developed measurement technologies can monitor surface water quality almost continuously, creating high-frequency multiparameter time series and raising the question of how best to extract insights from such rich data sets. Here we use spectral analysis to characterize the variability of water quality at the AgrHys observatory (Western France) over time scales ranging from 20 min to 12 years. Three years of daily sampling at the intensively farmed Kervidy-Naizin watershed reveal universal 1/f scaling for all 36 solutes, yielding spectral slopes of 1.05 ± 0.11 (mean ± standard deviation). These 36 solute concentrations show varying degrees of annual cycling, suggesting different controls on watershed export processes. Twelve years of daily samples of SO4, NO3, and dissolved organic carbon (DOC) show that 1/f scaling does not continue at frequencies below 1/year in those constituents, whereas a 12-year daily record of Cl shows a general 1/f trend down to the lowest measurable frequencies. Conversely, approximately 12 months of 20 min NO3 and DOC measurements show that at frequencies higher than 1/day, the spectra of these solutes steepen to slopes of roughly 3, and at time scales shorter than 2-3 h, the spectra flatten to slopes near zero, reflecting analytical noise. These results confirm and extend the recent discovery of universal fractal 1/f scaling in water quality at the relatively pristine Plynlimon watershed in Wales, further demonstrating the importance of advective-dispersive transport mixing in catchments. However, the steeper scaling at subdaily time scales suggests additional short-term damping of solute concentrations, potentially due to in-stream or riparian processes.

  2. Toward a periodic table of personality: Mapping personality scales between the five-factor model and the circumplex model.

    Science.gov (United States)

    Woods, Stephen A; Anderson, Neil R

    2016-04-01

    In this study, we examine the structures of 10 personality inventories (PIs) widely used for personnel assessment by mapping the scales of PIs to the lexical Big Five circumplex model resulting in a Periodic Table of Personality. Correlations between 273 scales from 10 internationally popular PIs with independent markers of the lexical Big Five are reported, based on data from samples in 2 countries (United Kingdom, N = 286; United States, N = 1,046), permitting us to map these scales onto the Abridged Big Five Dimensional Circumplex model (Hofstee, de Raad, & Goldberg, 1992). Emerging from our findings we propose a common facet framework derived from the scales of the PIs in our study. These results provide important insights into the literature on criterion-related validity of personality traits, and enable researchers and practitioners to understand how different PI scales converge and diverge and how compound PI scales may be constructed or replicated. Implications for research and practice are considered.

  3. World water dynamics: global modeling of water resources.

    Science.gov (United States)

    Simonovic, Slobodan P

    2002-11-01

    The growing scarcity of fresh and clean water is among the most important issues facing civilization in the 21st century. Despite the growing attention to a chronic, pernicious crisis in world's water resources our ability to correctly assess and predict global water availability, use and balance is still quite limited. An attempt is documented here in modeling global world water resources using system dynamics approach. Water resources sector (quantity and quality) is integrated with five sectors that drive industrial growth: population; agriculture; economy; nonrenewable resources; and persistent pollution. WorldWater model is developed on the basis of the last version of World3 model. Simulations of world water dynamics with WorldWater indicate that there is a strong relationship between the world water resources and future industrial growth of the world. It is also shown that the water pollution is the most important future water issue on the global level.

  4. Simulation of groundwater recharge from an aquifer storage recovery well under shallow water-table condition

    National Research Council Canada - National Science Library

    V. Goyal; B. S. Jhorar; R. S. Malik; T. Streck

    2009-01-01

    .... Saturated hydraulic conductivity was estimated through inverse modelling technique using experimental pressure head time pairs during the first aquifer storage recovery cycle from a piezometer and an observation well...

  5. Polder Effects on Sediment-to-Soil Conversion: Water Table, Residual Available Water Capacity, and Salt Stress Interdependence

    Directory of Open Access Journals (Sweden)

    Raymond Tojo Radimy

    2013-01-01

    Full Text Available The French Atlantic marshlands, reclaimed since the Middle Age, have been successively used for extensive grazing and more recently for cereal cultivation from 1970. The soils have acquired specific properties which have been induced by the successive reclaiming and drainage works and by the response of the clay dominant primary sediments, that is, structure, moisture, and salinity profiles. Based on the whole survey of the Marais Poitevin and Marais de Rochefort and in order to explain the mechanisms of marsh soil behavior, the work focuses on two typical spots: an undrained grassland since at least 1964 and a drained cereal cultivated field. The structure-hydromechanical profiles relationships have been established thanks to the clay matrix shrinkage curve. They are confronted to the hydraulic functioning including the fresh-to-salt water transfers and to the recording of tensiometer profiles. The CE1/5 profiles supply the water geochemical and geophysical data by their better accuracy. Associated to the available water capacity calculation they allow the representation of the parallel evolution of the residual available water capacity profiles and salinity profiles according to the plant growing and rooting from the mesophile systems of grassland to the hygrophile systems of drained fields.

  6. Stochastic Still Water Response Model

    DEFF Research Database (Denmark)

    Friis-Hansen, Peter; Ditlevsen, Ove Dalager

    2002-01-01

    In this study a stochastic field model for the still water loading is formulated where the statistics (mean value, standard deviation, and correlation) of the sectional forces are obtained by integration of the load field over the relevant part of the ship structure. The objective of the model...... is to establish the stochastic load field conditional on a given draft and trim of the vessel. The model contributes to a realistic modelling of the stochastic load processes to be used in a reliability evaluation of the ship hull. Emphasis is given to container vessels. The formulation of the model for obtaining...... the stochastic cargo container load field is based on a queuing and loading policy that assumes containers are handled by a first-come-first-serve policy. The load field is assumed to be Gaussian. The ballast system is imposed to counteract the angle of heel and to regulate both the draft and the trim caused...

  7. MODELS AND TABLES OF GROWTH OF ARTIFICIAL ORIGIN OAK FORESTS IN THE LOWER VOLGA REGION

    Directory of Open Access Journals (Sweden)

    Panchenko L. A.

    2013-11-01

    Full Text Available The article discusses the function of growth for the simulation of forest indices of individual tree element of the forest. Algorithm calculate tables of growth based on materials by eye-measuring taxation on the basis of patterns of variability of the amount of Room space of sections of stands of oak is proposed. Tables of growth of stands of different density are developed

  8. Modeling high-energy cosmic ray induced terrestrial muon flux: A lookup table

    CERN Document Server

    Atri, Dimitra

    2010-01-01

    On geological timescales, the Earth is likely to be exposed to an increased flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. Typical cosmic ray energies may be much higher than the ~ 1 GeV flux which normally dominates. These high-energy particles strike the Earth's atmosphere initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles. Secondary particles such as muons and thermal neutrons produced as a result of nuclear interactions are able to reach the ground, enhancing the radiation dose. Muons contribute 85% to the radiation dose from cosmic rays. This enhanced dose could be potentially harmful to the biosphere. This mechanism has been discussed extensively in literature but has never been quantified. Here, we have developed a lookup table that can be used to quantify this effect by modeling terrestrial muon flux from any arbitrary cosmic ra...

  9. Mathematical modeling and full-scale shaking table tests for multi-curve buckling restrained braces

    Institute of Scientific and Technical Information of China (English)

    C. S. Tsai; Yungchang Lin; Wenshin Chen; H. C. Su

    2009-01-01

    Buckling restrained braces (BRBs) have been widely applied in seismic mitigation since they were introduced in the 1970s. However, traditional BRBs have several disadvantages caused by using a steel tube to envelope the mortar to prevent the core plate from buckling, such as: complex interfaces between the materials used, uncertain precision, and time consumption during the manufacturing processes. In this study, a new device called the multi-curve buckling restrained brace (MC-BRB) is proposed to overcome these disadvantages. The new device consists of a core plate with multiple neck portions assembled to form multiple energy dissipation segments, and the enlarged segment, lateral support elements and constraining elements to prevent the BRB from buckling. The enlarged segment located in the middle of the core plate can be welded to the lateral support and constraining elements to increase buckling resistance and to prevent them from sliding during earthquakes. Component tests and a series of shaking table tests on a full-scale steel structure equipped with MC-BRBs were carried out to investigate the behavior and capability of this new BRB design for seismic mitigation. The experimental results illustrate that the MC-BRB possesses a stable mechanical behavior under cyclic loadings and provides good protection to structures during earthquakes. Also, a mathematical model has been developed to simulate the mechanical characteristics of BRBs.

  10. Study on soil-pile-structure-TMD interaction system by shaking table model test

    Institute of Scientific and Technical Information of China (English)

    楼梦麟; 王文剑

    2004-01-01

    The success of the tuned mass damper (TMD) in reducing wind-induced structural vibrations has been well established. However, from most of the recent numerical studies, it appears that for a structure situated on very soft soil, soilstructure interaction (SSI) could render a damper on the structure totally ineffective. In order to experimentally verify the SSI effect on the seismic performance ofTMD, a series of shaking table model tests have been conducted and the results are presented in this paper. It has been shown that the TMD is not as effective in controlling the seismic responses of structures built on soft soil sites due to the SSI effect. Some test results also show that a TMD device might have a negative impact ifthe SSI effect is neglected and the structure is built on a soft soil site. For structures constructed on a soil foundation, this research verifies that the SSI effect must be carefully understood before a TMD control system is designed to determine if the control is necessary and ifthe SSI effect must be considered when choosing the optimal parameters of the TMD device.

  11. Interference tables: a useful model for interference analysis in asynchronous multicarrier transmission

    Science.gov (United States)

    Medjahdi, Yahia; Terré, Michel; Ruyet, Didier Le; Roviras, Daniel

    2014-12-01

    In this paper, we investigate the impact of timing asynchronism on the performance of multicarrier techniques in a spectrum coexistence context. Two multicarrier schemes are considered: cyclic prefix-based orthogonal frequency division multiplexing (CP-OFDM) with a rectangular pulse shape and filter bank-based multicarrier (FBMC) with physical layer for dynamic spectrum access and cognitive radio (PHYDYAS) and isotropic orthogonal transform algorithm (IOTA) waveforms. First, we present the general concept of the so-called power spectral density (PSD)-based interference tables which are commonly used for multicarrier interference characterization in spectrum sharing context. After highlighting the limits of this approach, we propose a new family of interference tables called `instantaneous interference tables'. The proposed tables give the interference power caused by a given interfering subcarrier on a victim one, not only as a function of the spectral distance separating both subcarriers but also with respect to the timing misalignment between the subcarrier holders. In contrast to the PSD-based interference tables, the accuracy of the proposed tables has been validated through different simulation results. Furthermore, due to the better frequency localization of both PHYDYAS and IOTA waveforms, FBMC technique is demonstrated to be more robust to timing asynchronism compared to OFDM one. Such a result makes FBMC a potential candidate for the physical layer of future cognitive radio systems.

  12. Modeling Water Pollution of Soil

    Directory of Open Access Journals (Sweden)

    V. Doležel

    2008-01-01

    depth of 220–300 m below the terrain. As an alternative, thinner stoppers were considered, but this option was discarded.The aim of this paper is to describe the design of the stoppers applied to separate the two types of water along the contact horizon using Desai’s DSC theory (Distinct State Concept, and generalized plane strain in the multiphase problem of water flow in a porous medium. In addition, a comparison of some results from scale experimental models with numerical solutions was carried out. The intrinsic material properties of stoppers for numerical computations were obtained from physical and chemical laboratory tests. The models were evaluated for the complete underground work, particularly in its final stage of construction. 

  13. Control of a Thrust Alignment Table for Modeling the Coning Dynamics of a Spinning Spacecraft with a Follower Force

    Science.gov (United States)

    Halsmer, Dominic; Bennett, J. Damon; DeHaven, Max; Ligard, Vidar

    1999-01-01

    This document presents a system controlling the motion of a spherical air bearing used in the modeling of spacecraft dynamics and controls in a laboratory environment. The system is part of the Spinning Rocket Simulator (SRS), used to simulate the coning of spacecraft during a thrusting stage. The reaction force at the spherical air bearing supporting the spacecraft model must coincide with the thrust axis of the model for proper simulation. Therefore, the bearing is translated in a circular path to introduce a centrifugal force. This horizontal force along with the gravitational reaction force at the bearing combines to simulate the direction of the spacecraft's thrust force. The control system receives attitude information from the spacecraft model via a laser beam embedded in the model that impinges on a photosensitive array. The non-linear system is controlled using high-speed lookup tables and digital techniques. A vector-controlled motor and a stepper motor are given the necessary signals to accurately control the turntable and platform supporting the air bearing. Preliminary performance data is presented. Mechanical elements of the table and platform are described in detail. A wireless (RF) data path for all devices on the spacecraft model to an off-table command computer is also described.

  14. Uranium redistribution due to water table fluctuations in sandy wetland mesocosms

    Energy Technology Data Exchange (ETDEWEB)

    Gilson, Emily R.; Huang, Shan; Koster van Groos, Paul G.; Scheckel, Kirk G.; Qafoku, Odeta; Peacock, Aaron D.; Kaplan, Daniel I.; Jaffe, Peter R.

    2015-10-20

    In order to better understand the fate and stability of immobilized uranium (U) in wetland sediments, and how intermittent dry periods affect U stability, we dosed saturated wetland mesocosms planted with Scirpus acutus with low levels of uranyl acetate for 4 months before imposing a short drying and rewetting period. Concentrations of U in mesocosm effluent increased after drying and rewetting, but the cumulative amount of U released following the dry period constituted less than 1% of the total U immobilized in the soil during the 4 months prior. This low level of remobilization suggests, and XAS analyses confirm, that microbial reduction was not the primary means of U immobilization, as the U immobilized in mesocosms was primarily U(VI) rather than U(IV). Drying followed by re-wetting caused a redistribution of U downward in the soil profile and on to root surfaces. While the U on roots before drying was primarily associated with minerals, the U that relocated to the roots during drying and rewetting was bound diffusely to root surfaces. Results show that short periods of drought conditions in a wetland, which expose reduced sediments to air, may impact U distribution, but these conditions may not cause large releases of soil-bound U from planted wetlands to surface waters.

  15. Carbon dioxide flux and net primary production of a boreal treed bog: responses to warming and water table manipulations

    Science.gov (United States)

    Munir, T. M.; Perkins, M.; Kaing, E.; Strack, M.

    2014-09-01

    Mid-latitude treed bogs are significant carbon (C) stocks and are highly sensitive to global climate change. In a dry continental treed bog, we compared three sites; control, recent (1-3 years; experimental) and older drained (10-13 years; drained) with water levels at 38, 74 and 120 cm below the surface, respectively. At each site we measured carbon dioxide (CO2) fluxes and tree root respiration (Rr) (across hummock-hollow microtopography of the forest floor) and net primary production (NPP) of trees during the growing seasons (May to October) of 2011-2013. The carbon (C) balance was calculated by adding net CO2 exchange of the forest floor (NEff-Rr) to the NPP of the trees. From cooler and wetter 2011 to driest and warmest 2013, The control site was a~C sink of 92, 70 and 76 g m-2, experimental site was a C source of 14, 57 and 135 g m-2, and drained site was a progressively smaller source of 26, 23 and 13 g m-2, respectively. Although all microforms at the experimental site had large net CO2 emissions, the longer-term drainage and deeper water level at the drained site resulted in the replacement of mosses with vascular plants (shrubs) at the hummocks and lichens at the hollows leading to the highest CO2 uptake at drained hummocks and significant losses at hollows. The tree NPP was highest at the drained site. We also quantified the impact of climatic warming at all water table treatments by equipping additional plots with open-top chambers (OTCs) that caused a passive warming on average of ∼1 °C and differential air warming of ∼6 °C (at mid-day full sun) across the study years. Warming significantly enhanced the shrub growth and CO2 sink function of the drained hummocks (exceeding the cumulative respiration losses at hollows induced by the lowered water level × warming). There was an interaction of water level with warming across hummocks that resulted in largest net CO2 uptake at warmed drained hummocks. Thus in 2013, the warming treatment enhanced the

  16. Accounting for Water Insecurity in Modeling Domestic Water Demand

    Science.gov (United States)

    Galaitsis, S. E.; Huber-lee, A. T.; Vogel, R. M.; Naumova, E.

    2013-12-01

    Water demand management uses price elasticity estimates to predict consumer demand in relation to water pricing changes, but studies have shown that many additional factors effect water consumption. Development scholars document the need for water security, however, much of the water security literature focuses on broad policies which can influence water demand. Previous domestic water demand studies have not considered how water security can affect a population's consumption behavior. This study is the first to model the influence of water insecurity on water demand. A subjective indicator scale measuring water insecurity among consumers in the Palestinian West Bank is developed and included as a variable to explore how perceptions of control, or lack thereof, impact consumption behavior and resulting estimates of price elasticity. A multivariate regression model demonstrates the significance of a water insecurity variable for data sets encompassing disparate water access. When accounting for insecurity, the R-squaed value improves and the marginal price a household is willing to pay becomes a significant predictor for the household quantity consumption. The model denotes that, with all other variables held equal, a household will buy more water when the users are more water insecure. Though the reasons behind this trend require further study, the findings suggest broad policy implications by demonstrating that water distribution practices in scarcity conditions can promote consumer welfare and efficient water use.

  17. Oscillating water column structural model

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, Guild [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jepsen, Richard Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by a BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.

  18. Modelling of Water Turbidity Parameters in a Water Treatment Plant

    Directory of Open Access Journals (Sweden)

    A. S. KOVO

    2005-01-01

    Full Text Available The high cost of chemical analysis of water has necessitated various researches into finding alternative method of determining portable water quality. This paper is aimed at modelling the turbidity value as a water quality parameter. Mathematical models for turbidity removal were developed based on the relationships between water turbidity and other water criteria. Results showed that the turbidity of water is the cumulative effect of the individual parameters/factors affecting the system. A model equation for the evaluation and prediction of a clarifier’s performance was developed:Model: T = T0(-1.36729 + 0.037101∙10λpH + 0.048928t + 0.00741387∙alkThe developed model will aid the predictive assessment of water treatment plant performance. The limitations of the models are as a result of insufficient variable considered during the conceptualization.

  19. Identification of nitrate long term trends in Loire-Brittany river district (France) in connection with hydrogeological contexts, agricultural practices and water table level variations

    Science.gov (United States)

    Lopez, B.; Baran, N.; Bourgine, B.; Ratheau, D.

    2009-04-01

    The European Union (EU) has adopted directives requiring that Member States take measures to reach a "good" chemical status of water resources by the year 2015 (Water Framework Directive: WFD). Alongside, the Nitrates Directives (91/676/EEC) aims at controlling nitrogen pollution and requires Member States to identify groundwaters that contain more than 50 mg NO3 L-1 or could exceed this limit if preventive measures are not taken. In order to achieve these environmental objectives in the Loire-Brittany river basin, or to justify the non achievement of these objectives, a large dataset of nitrate concentrations (117.056 raw data distributed on 7.341 time-series) and water table level time-series (1.371.655 data distributed on 511 piezometers) is analysed from 1945 to 2007. The 156.700 sq km Loire-Brittany river basin shows various hydrogeological contexts, ranging from sedimentary aquifers to basement ones, with a few volcanic-rock aquifers. The knowledge of the evolution of agricultural practices is important in such a study and, even if this information is not locally available, agricultural practices have globally changed since the 1991 Nitrates Directives. The detailed dataset available for the Loire-Brittany basin aquifers is used to evaluate tools and to propose efficient methodologies for identifying and quantifying past and current trends in nitrate concentrations. Therefore, the challenge of this study is to propose a global and integrated approach which allows nitrate trend identifications for the whole Loire-Brittany river basin. The temporal piezometric behaviour of each aquifer is defined using geostatistical analyse of water table level time-series. This method requires the calculation of an experimental temporal variogram that can be fitted with a theoretical model valid for a large time range. Identification of contrasted behaviours (short term, annual or pluriannual water table fluctuations) allows a systematic classification of the Loire

  20. Water losses dynamic modelling in water distribution networks

    Science.gov (United States)

    Puleo, Valeria; Milici, Barbara

    2015-12-01

    In the last decades, one of the main concerns of the water system managers have been the minimisation of water losses, that frequently reach values of 30% or even 70% of the volume supplying the water distribution network. The economic and social costs associated with water losses in modern water supply systems are rapidly rising to unacceptably high levels. Furthermore, the problem of the water losses assumes more and more importance mainly when periods of water scarcity occur or when not sufficient water supply takes part in areas with fast growth. In the present analysis, a dynamic model was used for estimating real and apparent losses of a real case study. A specific nodal demand model reflecting the user's tank installation and a specific apparent losses module were implemented. The results from the dynamic model were compared with the modelling estimation based on a steady-state approach.

  1. Clusters of classical water models

    Science.gov (United States)

    Kiss, Péter T.; Baranyai, András

    2009-11-01

    The properties of clusters can be used as tests of models constructed for molecular simulation of water. We searched for configurations with minimal energies for a small number of molecules. We identified topologically different structures close to the absolute energy minimum of the system by calculating overlap integrals and enumerating hydrogen bonds. Starting from the dimer, we found increasing number of topologically different, low-energy arrangements for the trimer(3), the tetramer(6), the pentamer(6), and the hexamer(9). We studied simple models with polarizable point dipole. These were the BSV model [J. Brodholt et al., Mol. Phys. 86, 149 (1995)], the DC model [L. X. Dang and T. M. Chang, J. Chem. Phys. 106, 8149 (1997)], and the GCP model [P. Paricaud et al., J. Chem. Phys. 122, 244511 (2005)]. As an alternative the SWM4-DP and the SWM4-NDP charge-on-spring models [G. Lamoureux et al., Chem. Phys. Lett. 418, 245 (2006)] were also investigated. To study the impact of polarizability restricted to the plane of the molecule we carried out calculations for the SPC-FQ and TIP4P-FQ models, too [S. W. Rick et al., J. Chem. Phys. 101, 6141 (1994)]. In addition to them, justified by their widespread use even for near critical or surface behavior calculations, we identified clusters for five nonpolarizable models of ambient water, SPC/E [H. J. C. Berendsen et al., J. Phys. Chem. 91, 6269 (1987)], TIP4P [W. L. Jorgensen et al., J. Chem. Phys. 79, 926 (1983)], TIP4P-EW [H. W. Horn et al., J. Chem. Phys. 120, 9665 (2004)], and TIP4P/2005 [J. L. F. Abascal and C. Vega, J. Chem. Phys. 123, 234505 (2005)]. The fifth was a five-site model named TIP5P [M. W. Mahoney and W. L. Jorgensen, J. Chem. Phys. 112, 8910 (2000)]. To see the impact of the vibrations we studied the flexible SPC model. [K. Toukan and A. Rahman, Phys. Rev. B 31, 2643 (1985)]. We evaluated the results comparing them with experimental data and quantum chemical calculations. The position of the negative

  2. Mobility and transport of mercury and methylmercury in peat as a function of changes in water table regime and plant functional groups

    Science.gov (United States)

    Haynes, Kristine M.; Kane, Evan S.; Potvin, Lynette; Lilleskov, Erik A.; Kolka, Randall K.; Mitchell, Carl P. J.

    2017-02-01

    Climate change is likely to significantly affect the hydrology, ecology, and ecosystem function of peatlands, with potentially important but unclear impacts on mercury mobility within and transport from peatlands. Using a full-factorial mesocosm approach, we investigated the potential impacts on mercury mobility of water table regime changes (high and low) and vegetation community shifts (sedge-dominated, Ericaceae-dominated, or unmanipulated control) in peat monoliths at the PEATcosm mesocosm facility in Houghton, Michigan. Lower and more variable water table regimes and the loss of Ericaceae shrubs act significantly and independently to increase both total Hg and methylmercury concentrations in peat pore water and in spring snowmelt runoff. These differences are related to enhanced peat decomposition and internal regeneration of electron acceptors which are more strongly related to water table regime than to plant community changes. Loss of Ericaceae shrubs and an increase in sedge cover may also affect Hg concentrations and mobility via oxygen shuttling and/or the provision of labile root exudates. Altered hydrological regimes and shifting vegetation communities, as a result of global climate change, are likely to enhance Hg transport from peatlands to downstream aquatic ecosystems.

  3. Shaking table model test and engineering practice of a new gypsum-adobe walls dwelling in Xinjiang autonomous region, China

    Institute of Scientific and Technical Information of China (English)

    ZHOU Tie-gang; HU Xin; YU Chang-xia

    2008-01-01

    The paper introduces a new type of green building which suits for the construction of rural dwellings in Xinjiang, China. Results of the shaking table test on building model show that the single-layer gypsum-adobe structure has better seismic performance. And it also analyzes the construction features and engineering practice, which means that it is significant to extend this type of building to the drier regions in China.

  4. Mortality study of nickel-cadmium battery workers by the method of regression models in life tables.

    OpenAIRE

    1983-01-01

    The mortality experienced by a cohort of 3025 nickel-cadmium battery workers during the period 1946-81 has been investigated. Occupational histories were described in terms of some 75 jobs: eight with "high", 14 with "moderate" or slight, and 53 with minimal exposure to cadmium oxide (hydroxide). The method of regression models in life tables (RMLT) was used to compare the estimated cadmium exposures (durations of exposed employment) of those dying from causes of interest with those of matchi...

  5. Similar Materials in Large-scale Shaking Table Model Test%大型振动台试验相似材料研究

    Institute of Scientific and Technical Information of China (English)

    邹威; 许强; 刘汉香

    2012-01-01

    On the basis of analyzing and summarizing the research status of similar materials of rock which were u-sually used in physical simulation experiments of geological engineering in recent years, using the similar materials of shaking table model tests compounded by barite powder, quartz sand , gypsum and glycerol, through mechanical test of different proportion of materials, and considering the water content of similar materials, the contents of all kinds of materials and the regularity of the influence of the water content changing on the physical and mechanical properties of similar materials were studies and analyzed. It was found that water content had great influence on the compressive strength, cohesion, elastic modulus and friction angle of materials. According to the result, the proportion of similar material in shaking table model test was fixed finally. It was proved by the test that the mechanical index of this kind of material was stale, could meet the needs of the choice requirements of similar materials, convenient for pouring relatively large-scale model specimen once only. It applies to physical simulation experiments like large-scale shaking table model test.%在分析总结近几年岩土工程物理模拟试验中常用的岩质相似材料研究现状的基础上,采用重晶石粉、石英砂、石膏、甘油配制振动台模型试验相似材料,通过不同配比的材料力学试验,考虑相似材料的含水率,分析研究了各种材料含量以及含水率变化对相似材料物理力学性质的影响规律,发现含水率对材料的抗压强度、粘聚力、弹性模量、摩擦角有较大影响,根据试验结果最终确定了振动台试验相似材料配比.试验结果证明,该相似材料力学指标稳定,能很好地满足相似材料的选材要求,便于一次性浇注较大尺寸规模的模型试件,适用于大型振动台等物理模拟试验.

  6. 'Water window' compact, table-top laser plasma soft X-ray sources based on a gas puff target

    Energy Technology Data Exchange (ETDEWEB)

    Wachulak, P.W., E-mail: wachulak@gmail.co [Institute of Optoelectronics, Military University of Technology, ul. gen. S. Kaliskiego 2, 00-908 Warsaw (Poland); Bartnik, A.; Fiedorowicz, H.; Rudawski, P.; Jarocki, R.; Kostecki, J.; Szczurek, M. [Institute of Optoelectronics, Military University of Technology, ul. gen. S. Kaliskiego 2, 00-908 Warsaw (Poland)

    2010-05-15

    We have developed compact, high repetition, table-top soft-X-ray sources, based on a gas puff target, emitting in 'water window' spectral range at lambda = 2.88 nm from nitrogen gas target or, in 2-4 nm range of wavelengths, from argon gas target. Double stream gas puff target was pumped optically by commercial Nd:YAG laser, energy 0.74 J, pulse time duration 4 ns. Spatial distribution of laser-produced plasma was imaged using a pinhole camera. Using transmission grating spectrometer, argon and nitrogen emission spectra were obtained, showing strong emission in the 'water window' spectral range. Using AXUV100 detector the flux measurements of the soft-X-ray pulses were carried out and are presented. These debris free sources are table-top alternative for free electron lasers and synchrotron installations. They can be successfully employed in microscopy, spectroscopy and metrology experiments among others.

  7. Modeling water demand when households have multiple sources of water

    Science.gov (United States)

    Coulibaly, Lassina; Jakus, Paul M.; Keith, John E.

    2014-07-01

    A significant portion of the world's population lives in areas where public water delivery systems are unreliable and/or deliver poor quality water. In response, people have developed important alternatives to publicly supplied water. To date, most water demand research has been based on single-equation models for a single source of water, with very few studies that have examined water demand from two sources of water (where all nonpublic system water sources have been aggregated into a single demand). This modeling approach leads to two outcomes. First, the demand models do not capture the full range of alternatives, so the true economic relationship among the alternatives is obscured. Second, and more seriously, economic theory predicts that demand for a good becomes more price-elastic as the number of close substitutes increases. If researchers artificially limit the number of alternatives studied to something less than the true number, the price elasticity estimate may be biased downward. This paper examines water demand in a region with near universal access to piped water, but where system reliability and quality is such that many alternative sources of water exist. In extending the demand analysis to four sources of water, we are able to (i) demonstrate why households choose the water sources they do, (ii) provide a richer description of the demand relationships among sources, and (iii) calculate own-price elasticity estimates that are more elastic than those generally found in the literature.

  8. Modeling of Soil Water and Salt Dynamics and Its Effects on Root Water Uptake in Heihe Arid Wetland, Gansu, China

    Directory of Open Access Journals (Sweden)

    Huijie Li

    2015-05-01

    Full Text Available In the Heihe River basin, China, increased salinity and water shortages present serious threats to the sustainability of arid wetlands. It is critical to understand the interactions between soil water and salts (from saline shallow groundwater and the river and their effects on plant growth under the influence of shallow groundwater and irrigation. In this study, the Hydrus-1D model was used in an arid wetland of the Middle Heihe River to investigate the effects of the dynamics of soil water, soil salinization, and depth to water table (DWT as well as groundwater salinity on Chinese tamarisk root water uptake. The modeled soil water and electrical conductivity of soil solution (ECsw are in good agreement with the observations, as indicated by RMSE values (0.031 and 0.046 cm3·cm−3 for soil water content, 0.037 and 0.035 dS·m−1 for ECsw, during the model calibration and validation periods, respectively. The calibrated model was used in scenario analyses considering different DWTs, salinity levels and the introduction of preseason irrigation. The results showed that (I Chinese tamarisk root distribution was greatly affected by soil water and salt distribution in the soil profile, with about 73.8% of the roots being distributed in the 20–60 cm layer; (II root water uptake accounted for 91.0% of the potential maximal value when water stress was considered, and for 41.6% when both water and salt stress were considered; (III root water uptake was very sensitive to fluctuations of the water table, and was greatly reduced when the DWT was either dropped or raised 60% of the 2012 reference depth; (IV arid wetland vegetation exhibited a high level of groundwater dependence even though shallow groundwater resulted in increased soil salinization and (V preseason irrigation could effectively increase root water uptake by leaching salts from the root zone. We concluded that a suitable water table and groundwater salinity coupled with proper irrigation

  9. 基于多变量时间序列模型的大安市地下水埋深预测%Groundwater table forecast in Da’an City based on multivariate time series model

    Institute of Scientific and Technical Information of China (English)

    张真真; 卞建民; 韩宇; 张琳

    2015-01-01

    At first ,the influencing factors which had great relevance with groundwater table were determined by the principal component analysis (PCA ) method ,then established the groundwater table forecast model by using the multi-variate time series CAR model , according to the information as rainfall , evapovation , groundwater exploitation and groundwater tables and so on from 2000 to 2009 in Da’an City .Also the model was validated and applied to forecast the groundwater tables .The result shown that :The correlation coefficients of agricultural water consumption ,precipitation and evaporation with the groundwater table were 0 .56 ,0 .46 and -0 .13 , respectively .The contributions of the three factors with the groundwater table were 43 .09% ,27 .45% and 21 .39% ,respectively .The total contribution rate was 91 .93% and they were the major factors affecting the groundwater table .The relative error between forecasting value and measured value for confined and unconfined water tables was less than 5% .According to the forecast scheme ,when the rainfall was reduced 10% and evaporation was increased 9% , and the agricultural water consumption was increased 11% ,the confined water table will be reached 8 .70 m ,and the unconfined water table will be reached 4 .55 m .So in drought period ,the agricultural exploitation should be reduced properly ,the surface water irrigation should be increased , to reduce the possibility of soil desertification .%依据大安市2000—2009年的降水、蒸发、地下水开采量和地下水埋深等数据资料,首先利用主成分分析法确定了与地下水埋深相关性较大的影响因素,然后利用多变量时间序列CAR模型建立了大安市地下水埋深预测模型,并对模型进行验证,利用模型预测了地下水埋深。结果表明,农业用水量、降水量和蒸发量与地下水埋深的相关系数分别为:0.56,0.46,-0.13,三者对地下水埋深的贡献率分别为:43.09

  10. Nationwide water availability data for energy-water modeling.

    Energy Technology Data Exchange (ETDEWEB)

    Tidwell, Vincent Carroll; Zemlick, Katie M.; Klise, Geoffrey Taylor

    2013-11-01

    The purpose of this effort is to explore where the availability of water could be a limiting factor in the siting of new electric power generation. To support this analysis, water availability is mapped at the county level for the conterminous United States (3109 counties). Five water sources are individually considered, including unappropriated surface water, unappropriated groundwater, appropriated water (western U.S. only), municipal wastewater and brackish groundwater. Also mapped is projected growth in non-thermoelectric consumptive water demand to 2035. Finally, the water availability metrics are accompanied by estimated costs associated with utilizing that particular supply of water. Ultimately these data sets are being developed for use in the National Renewable Energy Laboratories' (NREL) Regional Energy Deployment System (ReEDS) model, designed to investigate the likely deployment of new energy installations in the U.S., subject to a number of constraints, particularly water.

  11. DEVELOPMENT OF WATER CIRCULATION MODEL INCLUDING IRRIGATION

    Science.gov (United States)

    Kotsuki, Shunji; Tanaka, Kenji; Kojiri, Toshiharu; Hamaguchi, Toshio

    It is well known that since agricultural water withdrawal has much affect on water circulation system, accurate analysis of river discharge or water balance are difficult with less regard for it. In this study, water circulation model composed of land surface model and distributed runoff model is proposed at 10km 10km resolution. In this model, irrigation water, which is estimated with land surface model, is introduced to river discharge analysis. The model is applied to the Chao Phraya River in Thailand, and reproduced seasonal water balance. Additionally, the discharge on dry season simulated with the model is improved as a result of including irrigation. Since the model, which is basically developed from global data sets, simulated seasonal change of river discharge, it can be suggested that our model has university to other river basins.

  12. Integrated Water and CGE Model of the Impacts of Water Policy on the Beijing's Economy and Output

    Institute of Scientific and Technical Information of China (English)

    Xia Jun; Deng Qun; Sun Yangbo

    2010-01-01

    The article used general equilibrium model to analyze the change of gross domestic product and industry output affected by water resources policies in Beijing City by using GEMPACK soft tool.The article researches on rules of water supply and demand,evaluating water resources,building water resources input and output table,establishing water computable general equilibrium model and stimulating water policy.The stimulation gives a scenario that increases water price by 10%.The result shows the following aspects.First,water resources policy infects gross domestic product and industry output in different ways.There are different behaviors in different industries as to the water policy.Agriculture industry has the same tendency as water price change and it has more sensitive to water quantity than to water price.For basic energy industries such as oil and chemistry and gas,they show diversity tendency.As to some high water consumer industry such as paper and textile etc.,water resource economic policy can infect them greatly and can promote them to accomplish more water-saving technology.Waste water and construction and service industries show the same tendency as to water policy.Second,government should pay more attention to water resource policy by macro economic administration.The simulation also shows that the output and supply and consumer price change more than expect as to water policy in a free market economic in water industry.So as to a government policy maker,one should be more carefully and prepare suitable forecast and plan to water policy and its negative impact.

  13. RECOVERY, A Mathematical Model to Predict the Temporal Response of Surface Water to Contaminated Sediments.

    Science.gov (United States)

    1994-11-01

    NewEngl d U.S. Art RAYo WAERAYaEPRIENCSATO Incudebilio grapicr•efe "M ( p prgam) 3dCOeTt L -E nv i Eroa BORpR of E. Nw Y ri.ARm E er Wter...constant = 8.206 x 10.5 atm m3/(gmole-kelvins) T = absolute temperature, kelvins. A temperature of 298K (25 °C) is assumed in the model. The parameter...bottom sediment material are shown in Table 3. Table 2 Concentrations of DDE and Lindane In Water Column Sampling Day DDE, ppt, X ± SD Undane, ppt, X

  14. Modeling Water Quality in Rivers

    Directory of Open Access Journals (Sweden)

    Liren Yu

    2005-01-01

    Full Text Available This study reports a PC software, used in a Windows-based environment, which was developed based on the first order reaction of Biological Oxygen Demand (BOD and a modified Streeter and Phelps equation, in order to simulate and determine the variations of Dissolved Oxygen (DO and of the BOD along with the studied river reaches. The software considers many impacts of environmental factors, such as the different type of discharges (concentrated or punctual source, tributary contribution, distributed source, nitrogenous BOD, BOD sedimentation, photosynthetic production and benthic demand of oxygen, and so on. The software has been used to model the DO profile along one river, with the aim to improve the water quality through suitable engineering measure.

  15. Modelling of bio-optical parameters of open ocean waters

    Directory of Open Access Journals (Sweden)

    Vadim N. Pelevin

    2001-12-01

    Full Text Available An original method for estimating the concentration of chlorophyll pigments, absorption of yellow substance and absorption of suspended matter without pigments and yellow substance in detritus using spectral diffuse attenuation coefficient for downwelling irradiance and irradiance reflectance data has been applied to sea waters of different types in the open ocean (case 1. Using the effective numerical single parameter classification with the water type optical index m as a parameter over the whole range of the open ocean waters, the calculations have been carried out and the light absorption spectra of sea waters tabulated. These spectra are used to optimize the absorption models and thus to estimate the concentrations of the main admixtures in sea water. The value of m can be determined from direct measurements of the downward irradiance attenuation coefficient at 500 nm or calculated from remote sensing data using the regressions given in the article. The sea water composition can then be readily estimated from the tables given for any open ocean area if that one parameter m characterizing the basin is known.

  16. Contrasting responses of growing season ecosystem CO2 exchange to variation in temperature and water table depth in two peatlands in northern Alberta, Canada

    Science.gov (United States)

    Adkinson, Angela C.; Syed, Kamran H.; Flanagan, Lawrence B.

    2011-03-01

    The large belowground carbon stocks in northern peatland ecosystems are potentially susceptible to release because of the expected differential responses of photosynthesis and respiration to climate change. This study compared net ecosystem CO2 exchange (NEE) measured using the eddy covariance technique at two peatland sites in northern Alberta, Canada, over three growing seasons (May-October). We observed distinct differences between the poor fen (Sphagnum moss dominated) and extreme-rich fen (Carex sedge dominated) sites for their responses of NEE to interannual variation in temperature and water table depth. The rates of growing season cumulative NEE at the poor fen were very similar among the three study years with an average (± standard deviation) of -110.1 ± 0.5 g C m-2 period-1. By contrast, the growing season cumulative NEE at the extreme-rich fen varied substantially among years (-34.5, -153.5, and -41.8 g C m-2 period-1 in 2004, 2005, and 2006, respectively), and net uptake of CO2 was lower (on average) than at the poor fen. Consistent with the eddy covariance measurements, analysis of 210Pb-dated peat cores also showed higher recent net rates of carbon accumulation in the poor fen than in the rich fen. Warm spring temperatures and sufficient water availability during the growing season resulted in the highest-magnitude ecosystem photosynthesis and NEE at the extreme-rich fen in 2005. Cool spring temperatures limited photosynthesis at the extreme-rich fen in 2004, while reduced water availability (lower water table) in 2006 constrained photosynthetic capacity relative to 2005, despite the warmer spring and summer temperatures in 2006. The combination of contrasting plant functional types and different peat water table features at our two study sites meant that the poor fen showed a reduced response of ecosystem CO2 exchange to environmental variation compared to the extreme-rich fen.

  17. Water-Table and Potentiometric-Surface Altitudes in the Upper Glacial, Magothy, and Lloyd Aquifers beneath Long Island, New York, March-April 2006

    Science.gov (United States)

    Monti, Jack; Busciolano, Ronald J.

    2009-01-01

    The U.S. Geological Survey (USGS), in cooperation with State and local agencies, systematically collects ground-water data at varying measurement frequencies to monitor the hydrologic situation on Long Island, New York. Each year during March and April, the USGS conducts a synoptic survey of hydrologic conditions to define the spatial distribution of the water table and potentiometric surfaces within the three main water-bearing units underlying Long Island - the upper glacial, Magothy, and Lloyd aquifers. These data and the maps constructed from them are commonly used in studies of Long Island's hydrology, and by water managers and suppliers for aquifer management and planning purposes. Water-level measurements made in 502 wells across Long Island during March-April 2006, were used to prepare the maps in this report. Measurements were made by the wetted-tape method to the nearest hundredth of a foot. Water-table and potentiometric-surface altitudes in these aquifers were contoured using these measurements. The water-table contours were interpreted using water-level data collected from 341 wells screened in the upper glacial aquifer and (or) shallow Magothy aquifer; the Magothy aquifer's potentiometric-surface contours were interpreted from measurements at 102 wells screened in the middle to deep Magothy aquifer and (or) contiguous and hydraulically connected Jameco aquifer; and the Lloyd aquifer's potentiometric-surface contours were interpreted from measurements at 59 wells screened in the Lloyd aquifer or contiguous and hydraulically connected North Shore aquifer. Many of the supply wells are in continuous operation and, therefore, were turned off for a minimum of 24 hours before measurements were made so that the water levels in the wells could recover to the level of the potentiometric head in the surrounding aquifer. Full recovery time at some of these supply wells can exceed 24 hours; therefore, water levels measured at these wells are assumed to be less

  18. A new approach for estimating groundwater table fluctuation response to rainfall events in North China Plain

    Science.gov (United States)

    Liao, Z.; Xie, X.; Ma, Z.

    2015-12-01

    A rise or decline in water table in response to water budget is a function of rainfall volume and groundwater depletion intensity. Most research have focus on estimating water table fluctuations among various shallow aquifer resulting from recharge and discharge change, however, the methods commonly applied are limited in that the subsurface system is more complex. In this paper, a reliable approach based on statistics theory is presented for quantifying the correlation relationship among water table, rainfall events and groundwater depletion process. The detail monitoring data are used to multivariate regression analysis and established the relationship model between water table and groundwater depletion in the proposed method. We further employed the model to obtain water table fluctuation trend with manual controlled depletion in different rainfall conditions. We also identify how this model applied to North China Plain and examine the water table error. The results show that controlling the depletion process based on different rainfall frequency can promote groundwater table recover and the model can provide a reliable method to groundwater management.

  19. Molecular mechanisms of water table lowering and nitrogen deposition in affecting greenhouse gas emissions from a Tibetan alpine wetland.

    Science.gov (United States)

    Wang, Hao; Yu, Lingfei; Zhang, Zhenhua; Liu, Wei; Chen, Litong; Cao, Guangmin; Yue, Haowei; Zhou, Jizhong; Yang, Yunfeng; Tang, Yanhong; He, Jin-Sheng

    2017-02-01

    Rapid climate change and intensified human activities have resulted in water table lowering (WTL) and enhanced nitrogen (N) deposition in Tibetan alpine wetlands. These changes may alter the magnitude and direction of greenhouse gas (GHG) emissions, affecting the climate impact of these fragile ecosystems. We conducted a mesocosm experiment combined with a metagenomics approach (GeoChip 5.0) to elucidate the effects of WTL (-20 cm relative to control) and N deposition (30 kg N ha(-1)  yr(-1) ) on carbon dioxide (CO2 ), methane (CH4 ) and nitrous oxide (N2 O) fluxes as well as the underlying mechanisms. Our results showed that WTL reduced CH4 emissions by 57.4% averaged over three growing seasons compared with no-WTL plots, but had no significant effect on net CO2 uptake or N2 O flux. N deposition increased net CO2 uptake by 25.2% in comparison with no-N deposition plots and turned the mesocosms from N2 O sinks to N2 O sources, but had little influence on CH4 emissions. The interactions between WTL and N deposition were not detected in all GHG emissions. As a result, WTL and N deposition both reduced the global warming potential (GWP) of growing season GHG budgets on a 100-year time horizon, but via different mechanisms. WTL reduced GWP from 337.3 to -480.1 g CO2 -eq m(-2) mostly because of decreased CH4 emissions, while N deposition reduced GWP from 21.0 to -163.8 g CO2 -eq m(-2) , mainly owing to increased net CO2 uptake. GeoChip analysis revealed that decreased CH4 production potential, rather than increased CH4 oxidation potential, may lead to the reduction in net CH4 emissions, and decreased nitrification potential and increased denitrification potential affected N2 O fluxes under WTL conditions. Our study highlights the importance of microbial mechanisms in regulating ecosystem-scale GHG responses to environmental changes.

  20. Impact of water table level on annual carbon and greenhouse gas balances of a restored peat extraction area

    Directory of Open Access Journals (Sweden)

    J. Järveoja

    2015-10-01

    Full Text Available Peatland restoration may provide a potential after-use option to mitigate the negative climate impact of abandoned peat extraction areas; currently, however, knowledge about restoration effects on the annual balances of carbon (C and greenhouse gas (GHG exchanges is still limited. The aim of this study was to investigate the impact of contrasting water table levels (WTL on the annual C and GHG balances of restoration treatments with high (Res-H and low (Res-L WTL relative to an unrestored bare peat (BP site. Measurements of carbon dioxide (CO2, methane (CH4 and nitrous oxide (N2O fluxes were conducted over a full year using the closed chamber method and complemented by measurements of abiotic controls and vegetation cover. Three years following restoration, the difference in the mean WTL resulted in higher bryophyte and lower vascular plant cover in Res-H relative to Res-L. Consequently, greater gross primary production and autotrophic respiration associated with greater vascular plant cover were observed in Res-L compared to Res-H. However, the means of the measured net ecosystem CO2 exchanges (NEE were not significantly different between Res-H and Res-L. Similarly, no significant differences were observed in the respective means of CH4 and N2O exchanges in Res-H and Res-L, respectively. In comparison to the two restored sites, greater net CO2, similar CH4 and greater N2O emissions occurred in BP. On the annual scale, Res-H, Res-L and BP were C sources of 111, 103 and 268 g C m−2 yr−1 and had positive GHG balances of 4.1, 3.8 and 10.2 t CO2 eq ha−1 yr−1, respectively. Thus, the different WTLs had a limited impact on the C and GHG balances in the two restored treatments three years following restoration. However, the C and GHG balances in Res-H and Res-L were considerably lower than in BP owing to the large reduction in CO2 emissions. This study therefore suggests that restoration may serve as an effective method to mitigate the negative

  1. Impact of water table level on annual carbon and greenhouse gas balances of a restored peat extraction area

    Science.gov (United States)

    Järveoja, Järvi; Peichl, Matthias; Maddison, Martin; Soosaar, Kaido; Vellak, Kai; Karofeld, Edgar; Teemusk, Alar; Mander, Ülo

    2016-05-01

    Peatland restoration may provide a potential after-use option to mitigate the negative climate impact of abandoned peat extraction areas; currently, however, knowledge about restoration effects on the annual balances of carbon (C) and greenhouse gas (GHG) exchanges is still limited. The aim of this study was to investigate the impact of contrasting mean water table levels (WTLs) on the annual C and GHG balances of restoration treatments with high (ResH) and low (ResL) WTL relative to an unrestored bare peat (BP) site. Measurements of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes were conducted over a full year using the closed chamber method and complemented by measurements of abiotic controls and vegetation cover. Three years following restoration, the difference in the mean WTL resulted in higher bryophyte and lower vascular plant cover in ResH relative to ResL. Consequently, greater gross primary production and autotrophic respiration associated with greater vascular plant cover were observed in ResL compared to ResH. However, the means of the measured net ecosystem CO2 exchanges (NEE) were not significantly different between ResH and ResL. Similarly, no significant differences were observed in the respective means of CH4 and N2O exchanges. In comparison to the two restored sites, greater net CO2, similar CH4 and greater N2O emissions occurred in BP. On the annual scale, ResH, ResL and BP were C sources of 111, 103 and 268 g C m-2 yr-1 and had positive GHG balances of 4.1, 3.8 and 10.2 t CO2 eq ha-1 yr-1, respectively. Thus, the different WTLs had a limited impact on the C and GHG balances in the two restored treatments 3 years following restoration. However, the C and GHG balances in ResH and ResL were considerably lower than in BP due to the large reduction in CO2 emissions. This study therefore suggests that restoration may serve as an effective method to mitigate the negative climate impacts of abandoned peat extraction areas.

  2. WATER QUALITY MODELING OF SUZHOU CREEK

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Water-quality models are important tools for improving river environment. In this paper, the project "Water Quality Modeling of the Suzhou Creek" was briefly described, including the choice and the principle of the model, the model study and methods, the calibration and verification of the stream model. A set of parameters about water environmental characteristic of the Suzhou Creek were put forward in the period of the third water dispatch experiment in 1999. It is necessary to point out that these parameters will change with the rehabilitation and construction of the Suzhou Creek.

  3. Water-table and potentiometric-surface altitudes in the Upper Glacial, Magothy, and Lloyd aquifers of Long Island, New York, April-May 2013

    Science.gov (United States)

    Como, Michael D.; Noll, Michael L.; Finkelstein, Jason S.; Monti, Jack; Busciolano, Ronald

    2015-01-01

    The U.S. Geological Survey (USGS), in cooperation with State and local agencies, systematically collects groundwater data at varying measurement frequencies to monitor the hydrologic conditions on Long Island, New York. Each year during April and May, the USGS conducts a synoptic survey of water levels to define the spatial distribution of the water table and potentiometric surfaces within the three main water-bearing units underlying Long Island—the upper glacial, Magothy, and Lloyd aquifers (Smolensky and others, 1989)—and the hydraulically connected Jameco (Soren, 1971) and North Shore aquifers (Stumm, 2001). These data and the maps constructed from them are commonly used in studies of Long Island's hydrology and are utilized by water managers and suppliers for aquifer management and planning purposes.

  4. Long-term rise of the Water Table in the Northeast US: Climate Variability, Land-Use Change, or Angry Beavers?

    Science.gov (United States)

    Boutt, D. F.

    2011-12-01

    The scientific evidence that humans are directly influencing the Earth's natural climate is increasingly compelling. Numerous studies suggest that climate change will lead to changes in the seasonality of surface water availability thereby increasing the need for groundwater development to offset those shortages. Research suggests that the Northeast region of the U.S. is experiencing significant changes to its' natural climate and hydrologic systems. Previous analysis of a long-term regional compilation of the water table response to the last 60 years of climate variability in New England documented a wide range of variability. The investigation evaluated the physical mechanisms, natural variability and response of aquifers in New England using 100 long term groundwater monitoring stations with 20 or more years of data coupled with 67 stream gages, 75 precipitation stations, and 43 temperature stations. Groundwater trends were calculated as normalized anomalies and analyzed with respect to regional compiled precipitation, temperature, and streamflow anomalies to understand the sensitivity of the aquifer systems to change. Interestingly, a trend and regression analysis demonstrate that water level fluctuations are producing statistically significant results with increasing water levels over at least the past thirty years at most (80 out of 100) well sites. In this contribution we investigate the causal mechanisms behind the observed ground water level trends using site-by-site land-use change assessments, cluster analysis, and spatial analysis of beaver populations (a possible proxy for beaver activity). Regionally, average annual precipitation has been slightly increasing since 1900, with 95% of the stations having statistically significant positive trends. Despite this, no correlation is observed between the magnitude of the annual precipitation trends and the magnitude of the groundwater level changes. Land-use change throughout the region has primarily taken

  5. Water Hammer Modelling and Simulation by GIS

    OpenAIRE

    Hariri Asli, K.; Haghi,A. K.; Hariri Asli, H.; E. Sabermaash Eshghi

    2012-01-01

    This work defined an Eulerian-based computational model compared with regression of the relationship between the dependent and independent variables for water hammer surge wave in transmission pipeline. The work also mentioned control of Unaccounted-for-Water (UFW) based on the Geography Information System (GIS) for water transmission pipeline. The experimental results of laboratory model and the field test results showed the validity of prediction achieved by computational model.

  6. Hybrid Sludge Modeling in Water Treatment Processes

    OpenAIRE

    Brenda, Marian

    2015-01-01

    Sludge occurs in many waste water and drinking water treatment processes. The numeric modeling of sludge is therefore crucial for developing and optimizing water treatment processes. Numeric single-phase sludge models mainly include settling and viscoplastic behavior. Even though many investigators emphasize the importance of modeling the rheology of sludge for good simulation results, it is difficult to measure, because of settling and the viscoplastic behavior. In this thesis, a new method ...

  7. Water Hammer Modelling and Simulation by GIS

    Directory of Open Access Journals (Sweden)

    K. Hariri Asli

    2012-01-01

    Full Text Available This work defined an Eulerian-based computational model compared with regression of the relationship between the dependent and independent variables for water hammer surge wave in transmission pipeline. The work also mentioned control of Unaccounted-for-Water (UFW based on the Geography Information System (GIS for water transmission pipeline. The experimental results of laboratory model and the field test results showed the validity of prediction achieved by computational model.

  8. Study on dynamic response of embedded long span corrugated steel culverts using scaled model shaking table tests and numerical analyses

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culverts due to strong earthquakes like the 1995 Hyogoken-nanbu earthquake. The dynamic strains of the embedded culvert models and the seismic soil pressure acting on the models due to sinusoidal and random strong motions were investigated. This study verified that the corrugated culvert model was subjected to dynamic horizontal forces (lateral seismic soil pressure) from the surrounding ground,which caused the large bending strains on the structure; and that the structures do not exceed the allowable plastic deformation and do not collapse completely during strong earthquake like Hyogoken-nanbu earthquake. The results obtained are useful for design and construction of embedded long span corrugated steel culverts in seismic regions.

  9. Applying the WEAP Model to Water Resource

    DEFF Research Database (Denmark)

    Gao, Jingjing; Christensen, Per; Li, Wei

    Water resources assessment is a tool to provide decision makers with an appropriate basis to make informed judgments regarding the objectives and targets to be addressed during the Strategic Environmental Assessment (SEA) process. The study shows how water resources assessment can be applied in SEA...... in assessing the effects on water resources using a case study on a Coal Industry Development Plan in an arid region in North Western China. In the case the WEAP model (Water Evaluation And Planning System) were used to simulate various scenarios using a diversity of technological instruments like irrigation...... efficiency, treatment and reuse of water. The WEAP model was applied to the Ordos catchment where it was used for the first time in China. The changes in water resource utilization in Ordos basin were assessed with the model. It was found that the WEAP model is a useful tool for water resource assessment...

  10. Characterisation of sea-water intrusion in the Pioneer Valley, Australia using hydrochemistry and three-dimensional numerical modelling

    Science.gov (United States)

    Werner, A. D.; Gallagher, M. R.

    2006-12-01

    Sea-water intrusion is actively contaminating fresh groundwater reserves in the coastal aquifers of the Pioneer Valley, north-eastern Australia. A three-dimensional sea-water intrusion model has been developed using the MODHMS code to explore regional-scale processes and to aid assessment of management strategies for the system. A sea-water intrusion potential map, produced through analyses of the hydrochemistry, hydrology and hydrogeology, offsets model limitations by providing an alternative appraisal of susceptibility. Sea-water intrusion in the Pioneer Valley is not in equilibrium, and a potential exists for further landward shifts in the extent of saline groundwater. The model required consideration of tidal over-height (the additional hydraulic head at the coast produced by the action of tides), with over-height values in the range 0.5-0.9 m giving improved water-table predictions. The effect of the initial water-table condition dominated the sensitivity of the model to changes in the coastal hydraulic boundary condition. Several salination processes are probably occurring in the Pioneer Valley, rather than just simple landward sea-water advancement from “modern” sources of marine salts. The method of vertical discretisation (i.e. model-layer subdivision) was shown to introduce some errors in the prediction of water-table behaviour.

  11. Using MODFLOW 2000 to model ET and recharge for shallow ground water problems.

    Science.gov (United States)

    Doble, Rebecca C; Simmons, Craig T; Walker, Glen R

    2009-01-01

    In environments with shallow ground water elevation, small changes in the water table can cause significant variations in recharge and evapotranspiration fluxes. Particularly, where ground water is close to the soil surface, both recharge and evapotranspiration are regulated by a thin unsaturated zone and, for accuracy, must be represented using nonconstant and often nonlinear relationships. The most commonly used ground water flow model today, MODFLOW, was originally designed with a modular structure with independent packages representing recharge and evaporation processes. Systems with shallow ground water, however, may be better represented using either a recharge function that varies with ground water depth or a continuous recharge and evapotranspiration function that is dependent on depth to water table. In situations where the boundaries between recharging and nonrecharging cells change with time, such as near a seepage zone, a continuous ground water flux relationship allows recharge rates to change with depth rather than having to calculate them at each stress period. This research article describes the modification of the MODFLOW 2000 recharge and segmented evapotranspiration packages into a continuous recharge-discharge function that allows ground water flux to be represented as a continuous process, dependent on head. The modifications were then used to model long-term recharge and evapotranspiration processes on a saline, semiarid floodplain in order to understand spatial patterns of salinization, and an overview of this process is given.

  12. WATER LAW AND MODEL OF RESPONSIBLE WATER USAGE

    Directory of Open Access Journals (Sweden)

    Dmitri Olegovitch Sivakov

    2017-03-01

    Full Text Available As it is known, the water law regulates dynamic social relationships concerning study, usage and protection of water objects, as well as their transformation. The water law explicitly regulates water economic activities. The regulatory method of the water law has a mixed nature and thus is not distinctive. It predetermines in some cases equality and independence of subjects of relationships (water usage agreement and in other – power and submission (permissive nature of water usage. The aim of the publication is to promote scientific ideas about the fate of the water law in order to make a further polygonal and productive discussion in which the reader is invited to participate. Scientific novelty. In 2016 the monograph of D.O. Sivakov “Water law: dynamics, problems, perspectives: monograph” (second edition, reviewed and updated. Moscow: Stolitsa, 2016. 540 p. was published. In 2017 the author reconsidered some conclusions of his monograph and applied scientific achievements of theory of state and law in water sphere. In accordance with this, it is important to mention research of Petrov D.E. related to issues of differentiation and integration of structural formations of Russian legal system. The scientific novelty of the article includes the synthesis of ideas of the monograph and some achievements of theory of state and law. Methods of research. The author of the article relies on some collective and individual monographic studies in the sphere of theory of state and law, natural resource law, arctic law, financial law. Basic results of research. The author promotes the model of responsible water usage. This model shall be based not on the unstable balance of economic and environmental interests (which shall practically lead to the domination of economic interests, but on the obligatory combination of economic activities with technologies, ensuring maximal preservation of water resources. Responsible water usage shall mean a system of

  13. Concentrations of selected trace inorganic constituents and synthetic organic compounds in the water-table aquifers in the Memphis area, Tennessee

    Science.gov (United States)

    McMaster, B.W.; Parks, William Scott

    1988-01-01

    Water quality samples for analysis of selected trace inorganic constituents and synthetic organic compounds were collected from 29 private or observation wells in alluvium and fluvial deposits of Quaternary and Tertiary Age. The alluvium and fluvial deposits are the water table aquifers in the Memphis area. In addition, nine wells were installed in Memphis Light, Gas and Water Division well fields so that samples could be collected and analyzed to characterize the quality of water in the fluvial deposits at these well fields. Samples from seven of these wells (two were dry) were analyzed for major constituents and properties of water as well as for selected trace inorganic constituents and synthetic organic compounds. Analyses of the water from most of the 36 wells sampled indicated ranges in concentration values for the trace inorganic constituents that agreed with those previously known, although some new maximum values were established. The analysis of water from four wells indicated that the water is or may be contaminated. Concentrations of barium (1,400 micrograms/L -- ug/L), strontium (1,100 ug/L), and arsenic (15 ug/L), along with specific conductance (1,420 microsiemens/centimeter--us/cm) were in water from one well in the alluvium. Low concentrations (0.02 to 0.04 ug/L) of the pesticides aldrin, DDT, endosulfan, and perthane were present in water from two wells in the fluvial deposits. Water from one of these wells also contained 1,1,1 trichloroethane (4.4 ug/L). Analysis of water from another well in the fluvial deposits indicated values for specific conductance (1,100 uS/cm), alkalinity (508 milligrams per liter -- mg/L -- as CaCO3), hardness (550 mg/L as CaCO3), chloride (65 mg/L), and barium (240 ug/L) that are high for water from the fluvial deposits. (USGS)

  14. Modeling rapid mass movements using the shallow water equations

    Directory of Open Access Journals (Sweden)

    S. Hergarten

    2014-11-01

    Full Text Available We propose a new method to model rapid mass movements on complex topography using the shallow water equations in Cartesian coordinates. These equations are the widely used standard approximation for the flow of water in rivers and shallow lakes, but the main prerequisite for their application – an almost horizontal fluid table – is in general not satisfied for avalanches and debris flows in steep terrain. Therefore, we have developed appropriate correction terms for large topographic gradients. In this study we present the mathematical formulation of these correction terms and their implementation in the open source flow solver GERRIS. This novel approach is evaluated by simulating avalanches on synthetic and finally natural topographies and the widely used Voellmy flow resistance law. The results are tested against analytical solutions and the commercial avalanche model RAMMS. The overall results are in excellent agreement with the reference system RAMMS, and the deviations between the different models are far below the uncertainties in the determination of the relevant fluid parameters and involved avalanche volumes in reality. As this code is freely available and open source, it can be easily extended by additional fluid models or source areas, making this model suitable for simulating several types of rapid mass movements. It therefore provides a valuable tool assisting regional scale natural hazard studies.

  15. Nambe Pueblo Water Budget and Forecasting model.

    Energy Technology Data Exchange (ETDEWEB)

    Brainard, James Robert

    2009-10-01

    This report documents The Nambe Pueblo Water Budget and Water Forecasting model. The model has been constructed using Powersim Studio (PS), a software package designed to investigate complex systems where flows and accumulations are central to the system. Here PS has been used as a platform for modeling various aspects of Nambe Pueblo's current and future water use. The model contains three major components, the Water Forecast Component, Irrigation Scheduling Component, and the Reservoir Model Component. In each of the components, the user can change variables to investigate the impacts of water management scenarios on future water use. The Water Forecast Component includes forecasting for industrial, commercial, and livestock use. Domestic demand is also forecasted based on user specified current population, population growth rates, and per capita water consumption. Irrigation efficiencies are quantified in the Irrigated Agriculture component using critical information concerning diversion rates, acreages, ditch dimensions and seepage rates. Results from this section are used in the Water Demand Forecast, Irrigation Scheduling, and the Reservoir Model components. The Reservoir Component contains two sections, (1) Storage and Inflow Accumulations by Categories and (2) Release, Diversion and Shortages. Results from both sections are derived from the calibrated Nambe Reservoir model where historic, pre-dam or above dam USGS stream flow data is fed into the model and releases are calculated.

  16. STORM WATER MANAGEMENT MODEL (SWMM) MODERNIZATION

    Science.gov (United States)

    The U.S. Environmental Protection Agency's Water Supply and Water Resources Division in partnership with the consulting firm of CDM to redevelop and modernize the Storm Water Management Model (SWMM). In the initial phase of this project EPA rewrote SWMM's computational engine usi...

  17. Microbial and metabolic profiling reveal strong influence of water table and land-use patterns on classification of degraded tropical peatlands

    Science.gov (United States)

    Mishra, S.; Lee, W. A.; Hooijer, A.; Reuben, S.; Sudiana, I. M.; Idris, A.; Swarup, S.

    2014-04-01

    Tropical peatlands from southeast Asia are undergoing extensive drainage, deforestation and degradation for agriculture and human settlement purposes. This is resulting in biomass loss and subsidence of peat from its oxidation. Molecular profiling approaches were used to understand the relative influences of different land-use patterns, hydrological and physicochemical parameters on the state of degraded tropical peatlands. As microbial communities play a critical role in biogeochemical cascades in the functioning of peatlands, we used microbial and metabolic profiles as surrogates of community structure and functions, respectively. Profiles were generated from 230 bacterial 16 S rDNA fragments and 145 metabolic markers of 46 samples from 10 sites, including those from above and below water table in a contiguous area of 48 km2 covering five land-use types. These were degraded forest, degraded land, oil palm plantation, mixed crop plantation and settlements. Bacterial profiles were most influenced by variations in water table and land-use patterns, followed by age of drainage and peat thickness in that order. Bacterial profiling revealed differences in sites, based on the duration and frequency of water table fluctuations and on oxygen availability. Mixed crop plantations had the most diverse bacterial and metabolic profiles. Metabolic profiling, being closely associated with biogeochemical functions, could distinguish communities not only based on land-use types but also their geographic locations, thus providing a finer resolution than bacterial profiles. Agricultural inputs, such as nitrates, were highly associated with bacterial community structure of oil palm plantations, whereas phosphates and dissolved organic carbon influenced those from mixed crop plantations and settlements. Our results provide a basis for adopting molecular marker-based approaches to classify peatlands and determine relative importance of factors that influence peat functioning. Our

  18. Parameter and model uncertainty in a life-table model for fine particles (PM2.5: a statistical modeling study

    Directory of Open Access Journals (Sweden)

    Jantunen Matti J

    2007-08-01

    Full Text Available Abstract Background The estimation of health impacts involves often uncertain input variables and assumptions which have to be incorporated into the model structure. These uncertainties may have significant effects on the results obtained with model, and, thus, on decision making. Fine particles (PM2.5 are believed to cause major health impacts, and, consequently, uncertainties in their health impact assessment have clear relevance to policy-making. We studied the effects of various uncertain input variables by building a life-table model for fine particles. Methods Life-expectancy of the Helsinki metropolitan area population and the change in life-expectancy due to fine particle exposures were predicted using a life-table model. A number of parameter and model uncertainties were estimated. Sensitivity analysis for input variables was performed by calculating rank-order correlations between input and output variables. The studied model uncertainties were (i plausibility of mortality outcomes and (ii lag, and parameter uncertainties (iii exposure-response coefficients for different mortality outcomes, and (iv exposure estimates for different age groups. The monetary value of the years-of-life-lost and the relative importance of the uncertainties related to monetary valuation were predicted to compare the relative importance of the monetary valuation on the health effect uncertainties. Results The magnitude of the health effects costs depended mostly on discount rate, exposure-response coefficient, and plausibility of the cardiopulmonary mortality. Other mortality outcomes (lung cancer, other non-accidental and infant mortality and lag had only minor impact on the output. The results highlight the importance of the uncertainties associated with cardiopulmonary mortality in the fine particle impact assessment when compared with other uncertainties. Conclusion When estimating life-expectancy, the estimates used for cardiopulmonary exposure

  19. Litter type affects the activity of aerobic decomposers in a boreal peatland more than site nutrient and water table regimes

    Directory of Open Access Journals (Sweden)

    P. Straková

    2011-09-01

    Full Text Available Peatlands are carbon (C storage ecosystems sustained by a high water table (WT. High WT creates anoxic conditions that suppress the activity of aerobic decomposers and provide conditions for peat accumulation. Peatland function can be dramatically affected by WT drawdown caused by climate and/or land-use change. Aerobic decomposers are directly affected by WT drawdown through environmental factors such as increased oxygenation and nutrient availability. Additionally, they are indirectly affected via changes in plant community composition and litter quality. We studied the relative importance of direct and indirect effects of WT drawdown on aerobic decomposer activity in plant litter at two stages of decomposition (incubated in the field for 1 or 2 years. We did this by profiling 11 extracellular enzymes involved in the mineralization of organic C, nitrogen (N, phosphorus (P and sulphur. Our study sites represented a three-stage chronosequence from pristine to short-term (years and long-term (decades WT drawdown conditions under two nutrient regimes (bog and fen. The litter types included reflected the prevalent vegetation: Sphagnum mosses, graminoids, shrubs and trees.

    Litter type was the main factor shaping microbial activity patterns and explained about 30 % of the variation in enzyme activities and activity allocation. Overall, enzyme activities were higher in vascular plant litters compared to Sphagnum litters, and the allocation of enzyme activities towards C or nutrient acquisition was related to the initial litter quality (chemical composition. Direct effects of WT regime, site nutrient regime and litter decomposition stage (length of incubation period summed to only about 40 % of the litter type effect. WT regime alone explained about 5 % of the variation in enzyme activities and activity allocation. Generally, enzyme activity increased following the long-term WT drawdown and the activity allocation turned from P

  20. Flood Water Crossing: Laboratory Model Investigations for Water Velocity Reductions

    Directory of Open Access Journals (Sweden)

    Kasnon N.

    2014-01-01

    Full Text Available The occurrence of floods may give a negative impact towards road traffic in terms of difficulties in mobilizing traffic as well as causing damage to the vehicles, which later cause them to be stuck in the traffic and trigger traffic problems. The high velocity of water flows occur when there is no existence of objects capable of diffusing the water velocity on the road surface. The shape, orientation and size of the object to be placed beside the road as a diffuser are important for the effective flow attenuation of water. In order to investigate the water flow, a laboratory experiment was set up and models were constructed to study the flow velocity reduction. The velocity of water before and after passing through the diffuser objects was investigated. This paper focuses on laboratory experiments to determine the flow velocity of the water using sensors before and after passing through two best diffuser objects chosen from a previous flow pattern experiment.

  1. Integrated water resources modelling for assessing sustainable water governance

    Science.gov (United States)

    Skoulikaris, Charalampos; Ganoulis, Jacques; Tsoukalas, Ioannis; Makropoulos, Christos; Gkatzogianni, Eleni; Michas, Spyros

    2015-04-01

    Climatic variations and resulting future uncertainties, increasing anthropogenic pressures, changes in political boundaries, ineffective or dysfunctional governance of natural resources and environmental degradation are some of the most fundamental challenges with which worldwide initiatives fostering the "think globally, act locally" concept are concerned. Different initiatives target the protection of the environment through sustainable development; Integrated Water Resources Management (IWRM) and Transboundary Water Resources Management (TWRM) in the case of internationally shared waters are frameworks that have gained wide political acceptance at international level and form part of water resources management planning and implementation on a global scale. Both concepts contribute in promoting economic efficiency, social equity and environmental sustainability. Inspired by these holistic management approaches, the present work describes an effort that uses integrated water resources modelling for the development of an integrated, coherent and flexible water governance tool. This work in which a sequence of computer based models and tools are linked together, aims at the evaluation of the sustainable operation of projects generating renewable energy from water as well as the sustainability of agricultural demands and environmental security in terms of environmental flow under various climatic and operational conditions. More specifically, catchment hydrological modelling is coupled with dams' simulation models and thereafter with models dedicated to water resources management and planning,while the bridging of models is conducted through geographic information systems and custom programming tools. For the case of Mesta/Nestos river basin different priority rules in the dams' operational schedule (e.g. priority given to power production as opposed to irrigation needs and vice versa), as well as different irrigation demands, e.g. current water demands as opposed to

  2. Modelling of Buckingham Canal water quality.

    Science.gov (United States)

    Abbasi, S A; Khan, F I; Sentilvelan, K; Shabudeen, A

    2002-10-01

    The paper presents a case study of the modelling of the water quality of a canal situated in a petrochemical industrial complex, which receives wastewaters from Madras Refineries Limited (MRL), and Madras Fertilizers Limited (MFL). The canal well known Buckingham Canal which passes through Chennai (Madras), India has been modelled using the software QUAL2E-UNCAS. After testing and validation of the model, simulations have been carried out. The exercise enables forecasting the impacts of different seasons, base flows, and waste water inputs on the water quality of the Buckingham Canal. It also enables development of water management strategies.

  3. Systems modelling for effective mine water management

    Energy Technology Data Exchange (ETDEWEB)

    Cote, C.M.; Moran, C.J.; Hedemann, C.J.; Koch, C. [University of Queensland, Brisbane, Qld. (Australia)

    2010-12-15

    Concerns about the difficulties in securing water have led the Australian coal mining industry to seek innovative ways to improve its water management and to adopt novel strategies that will lead to less water being used and more water being reused. Simulation tools are essential to assess current water management performance and to predict the efficiency of potential strategies. As water systems on coal mines are complex and consist of various inter-connected elements, a systems approach was selected, which views mine site water management as a system that obtains water from various sources (surface, groundwater), provides sufficient water of suitable quality to the mining tasks (coal beneficiation, dust suppression, underground operations) and maintains environmental performance. In this paper, the model is described and its calibration is illustrated. The results of applying the model for the comparison of the water balances of 7 coal mines in the northern Bowen Basin (Queensland, Australia) are presented. The model is used to assess the impact of applying specific water management strategies. Results show that a simple systems model is an appropriate tool for assessing site performance, for providing guidance to improve performance through strategic planning, and for guiding adoption of site objectives.

  4. A Theoretical Model of Water and Trade

    Science.gov (United States)

    Dang, Q.; Konar, M.; Reimer, J.; Di Baldassarre, G.; Lin, X.; Zeng, R.

    2015-12-01

    Water is an essential factor of agricultural production. Agriculture, in turn, is globalized through the trade of food commodities. In this paper, we develop a theoretical model of a small open economy that explicitly incorporates water resources. The model emphasizes three tradeoffs involving water decision-making that are important yet not always considered within the existing literature. One tradeoff focuses on competition for water among different sectors when there is a shock to one of the sectors only, such as trade liberalization and consequent higher demand for the product. A second tradeoff concerns the possibility that there may or may not be substitutes for water, such as increased use of sophisticated irrigation technology as a means to increase crop output in the absence of higher water availability. A third tradeoff explores the possibility that the rest of the world can be a source of supply or demand for a country's water-using products. A number of propositions are proven. For example, while trade liberalization tends to increase water use, increased pressure on water supplies can be moderated by way of a tax that is derivable with observable economic phenomena. Another example is that increased riskiness of water availability tends to cause water users to use less water than would be the case under profit maximization. These theoretical model results generate hypotheses that can be tested empirically in future work.

  5. HCMM energy budget data as a model input for assessing regions of high potential ground-water pollution

    Science.gov (United States)

    Moore, D. G. (Principal Investigator); Heilman, J.; Tunheim, J.

    1978-01-01

    The author has identified the following significant results. Analysis of soil temperature and water table data indicated that shallow aquifers appear to produce a heat sink effect when the depth to water table is approximately four meters or less.

  6. Building Water Models, A Different Approach

    CERN Document Server

    Izadi, Saeed; Onufriev, Alexey V

    2014-01-01

    Simplified, classical models of water are an integral part of atomistic molecular simulations, especially in biology and chemistry where hydration effects are critical. Yet, despite several decades of effort, these models are still far from perfect. Presented here is an alternative approach to constructing point charge water models - currently, the most commonly used type. In contrast to the conventional approach, we do not impose any geometry constraints on the model other than symmetry. Instead, we optimize the distribution of point charges to best describe the "electrostatics" of the water molecule, which is key to many unusual properties of liquid water. The search for the optimal charge distribution is performed in 2D parameter space of key lowest multipole moments of the model, to find best fit to a small set of bulk water properties at room temperature. A virtually exhaustive search is enabled via analytical equations that relate the charge distribution to the multipole moments. The resulting "optimal"...

  7. An improved shallow water equation model for water animation

    Science.gov (United States)

    Ai, Mingjing; Du, Anding; Xu, Han; Niu, Jianwei

    2017-03-01

    In this paper, we proposed a new scheme for simulating water flows under shallow water assumption. The method is an extension of traditional shallow water equations. In contrast to traditional methods, we design a dynamic coordinate system for modeling in order to efficiently simulate water flows. Within this system, we derive our specialized shallow water equations directly from the Navier-Stockes equation. At the same time, we develop an implicit mechanism for solving the advection term and a vector projection operator for solving the external forces acting on water. We also present a two-way coupling method for simulating the interaction between water and rigid solid. The experimental results show that the proposed scheme can achieve a more realistic and accurate water model compared with the traditional methods, especially when the solid surfaces are too steep. Also we demonstrate the efficiency of our method in several scenes, all run at least 50 frames per second on average which allows real-time simulation.

  8. Deriving Extensional Spatial Composition Tables

    Science.gov (United States)

    El-Geresy, Baher; Abdelmoty, Alia I.; Ware, Andrew J.

    Spatial composition tables are fundamental tools for the realisation of qualitative spatial reasoning techniques. Studying the properties of these tables in relation to the spatial calculi they are based on is essential for understanding the applicability of these calculi and how they can be extended and generalised. An extensional interpretation of a spatial composition table is an important property that has been studied in the literature and is used to determine the validity of the table for the models it is proposed for. It provides means for consistency checking of ground sets of relations and for addressing spatial constraint satisfaction problems. Furthermore, two general conditions that can be used to test for extensionality of spatial composition tables are proposed and applied to the RCC8 composition table to verify the allowable models in this calculus.

  9. Magnetic susceptibility as a proxy for the hydrobiogeochemical cycling of iron within the water table fluctuation zone at hydrocarbon contaminated sites

    Science.gov (United States)

    Atekwana, E. A.; Enright, A.; Atekwana, E. A.; Beaver, C. L.; Rossbach, S.; Slater, L. D.; Ntarlagiannis, D.

    2016-12-01

    Sharp redox gradients are indicative of enhanced biogeochemical activity and occur at or near the water table. Hydrologic forcing drives changes in redox state and oxygen levels, enhancing the elemental cycling of metals, and coupling different biogeochemical cycles. These coupled hydrobiogeochemical cycles are often difficult to study in the field using geochemical and microbial proxies because of direct sampling limitations, the costs associated with these techniques, and because the dynamic nature of these processes complicates the interpretation of single time point measurements, which may not give accurate representations of prevailing conditions. Geophysical techniques can provide both the spatial and temporal resolution needed to elucidate these processes. Here we investigated the use of magnetic susceptibility (c) as a viable proxy for understanding the biogeochemical cycling of iron at several hydrocarbon contaminated sites where active intrinsic bioremediation is occurring. We performed borehole c logging using a Bartington c probe in the field as well as made c measurements on core samples retrieved from the field sites. Our results show the following: (1) in both sulfate-rich and sulfate-poor aquifers, excursions in c are coincident with zones of free product contamination and are limited to the water table fluctuation (smear) zone; (2) c values within the free product plume and contamination source zones are higher compared to values within the dissolved product plume; (3) high c coincides with zones of elevated Fe (II) and Fe (III) concentrations extracted from aquifer solids; and (4) the mixed valence magnetite and greigite were the dominant magnetic minerals. The c excursions are limited to the water table fluctuation zones because fluctuating water level conditions are hot beds for microbial activity due to the steep hydrocarbon and nutrients and consequently redox gradients. High water levels during periods of recharge favor anaerobic conditions

  10. Shallow water modeling of Antarctic Bottom Water crossing the equator

    Science.gov (United States)

    Choboter, Paul F.; Swaters, Gordon E.

    2004-03-01

    The dynamics of abyssal equator-crossing flows are examined by studying simplified models of the flow in the equatorial region in the context of reduced-gravity shallow water theory. A simple "frictional geostrophic" model for one-layer cross-equatorial flow is described, in which geostrophy is replaced at the equator by frictional flow down the pressure gradient. This model is compared via numerical simulations to the one-layer reduced-gravity shallow water model for flow over realistic equatorial Atlantic Ocean bottom topography. It is argued that nonlinear advection is important at key locations where it permits the current to flow against a pressure gradient, a mechanism absent in the frictional geostrophic model and one of the reasons this model predicts less cross-equatorial flow than the shallow water model under similar conditions. Simulations of the shallow water model with an annually varying mass source reproduce the correct amplitude of observed time variability of cross-equatorial flow. The time evolution of volume transport across specific locations suggests that mass is stored in an equatorial basin, which can reduce the amplitude of time dependence of fluid actually proceeding into the Northern Hemisphere as compared to the amount entering the equatorial basin. Observed time series of temperature data at the equator are shown to be consistent with this hypothesis.

  11. Flood Water Model Logan K. kuiper

    Science.gov (United States)

    Kuiper, L. K.

    2013-05-01

    A mathematical model is developed to simulate flood water movement. Specifically, the model applies to situations where water depth is much smaller than the width or length of the water body, and resistance to flow from obstructions such as trees and structures is minimal. The model is applicable to many situations and in some cases may be able to suggest flood alleviation procedures. The derivation of the discretized form of the time dependant nonlinear equation governing the flow is based upon water conservation and the ability to approximate water flow rate (L2/T) as a function of the gradient of water surface elevation and water depth using the Manning equation. The flow equation is discretized using four sided finite elements. The resulting set of simultaneous nonlinear equations is solved iteratively using a conjugate gradient solver. To check for model programming error, a simple problem with constant water depth and constant water surface elevation gradient is checked against the Manning equation. An application of the model to a situation similar to the 2010 flood in northern Belize is ongoing.

  12. Water-table and Potentiometric-surface altitudes in the Upper Glacial, Magothy, and Lloyd aquifers beneath Long Island, New York, April-May 2010

    Science.gov (United States)

    Monti, Jack; Como, Michael D.; Busciolano, Ronald

    2013-01-01

    The U.S. Geological Survey (USGS), in cooperation with State and local agencies, systematically collects groundwater data at varying measurement frequencies to monitor the hydrologic conditions on Long Island, New York. Each year during April and May, the USGS conducts a synoptic survey of water levels to define the spatial distribution of the water table and potentiometric surfaces within the three main water-bearing units underlying Long Island—the upper glacial, Magothy, and Lloyd aquifers (Smolensky and others, 1989)—and the hydraulically connected Jameco (Soren, 1971) and North Shore aquifers (Stumm, 2001). These data and the maps constructed from them are commonly used in studies of Long Island’s hydrology and are used by water managers and suppliers for aquifer management and planning purposes. Water-level measurements made in 503 monitoring wells, a network of observation and supply wells, and 16 streamgage locations across Long Island during April–May 2010 were used to prepare the maps in this report. Measurements were made by the wetted-tape method to the nearest hundredth of a foot. Water-table and potentiometric-surface altitudes in these aquifers were contoured by using these measurements. The water-table contours were interpreted by using water-level data collected from 16 streamgages, 349 observation wells, and 1 supply well screened in the upper glacial aquifer and (or) shallow Magothy aquifer; the Magothy aquifer’s potentiometric-surface contours were interpreted from measurements at 67 observation wells and 27 supply wells screened in the middle to deep Magothy aquifer and (or) the contiguous and hydraulically connected Jameco aquifer. The Lloyd aquifer’s potentiometric-surface contours were interpreted from measurements at 55 observation wells and 4 supply wells screened in the Lloyd aquifer or the contiguous and hydraulically connected North Shore aquifer. Many of the supply wells are in continuous operation and, therefore, were

  13. An input-output table based analysis on the virtual water by sectors with the five northwest provinces in China

    Science.gov (United States)

    Shi, Chenchen; Zhan, Jinyan

    Virtual water refers to the volumes of water required to produce a commodity or service. It reflects human's actual consumption of water resources and therefore has certain significance in water resources management. Over the years, the concept of virtual water has caught the attentions of water manager and decision maker. In order to utilize this concept, the accounting and estimation of virtual water is the foundation that lies in this issue. Till now, the accounting methods mainly include the method provided by Food and Agriculture Organization of the United Nations (FAO), water footprint and input-output analysis method. In this paper, we chose Northwest China, which is a typical arid region that is facing with rapid economic development, as the study area and built an Input-Output (IO) analysis method to estimate virtual water among different industry sectors in the northwest China. The accounting and estimation results could be used to give suggestions to increase water use efficiency and promote virtual water trade in the study area. Comparison of the proposed method with other prevailing method was also analyzed. The introduced method could be utilized for accounting and estimation of virtual water by sectors, with its superiority in characterizing industrial water consumption and the accounting results could lend certain credence to the water resource management and industrial transformation for the future economic development of northwest China.

  14. Modelling proton transfer in water molecule chains

    CERN Document Server

    Korzhimanov, Artem; Shutova, Tatiana; Samuelsson, Goran

    2011-01-01

    The process of protons transport in molecular water chains is of fundamental interest for many biological systems. Although many features of such systems can be analyzed using large-scale computational modeling, other features are better understood in terms of simplified model problems. Here we have tested, analytically and numerically, a model describing the classical proton hopping process in molecular water chains. In order to capture the main features of the proton hopping process in such molecular chains, we use a simplified model for our analysis. In particular, our discrete model describes a 1D chain of water molecules situated in an external protein channel structure, and each water molecule is allowed to oscillate around its equilibrium point in this system, while the protons are allowed to move along the line of neighboring oxygen atoms. The occurrence and properties of nonlinear solitary transport structures, allowing for much faster proton transport, are discussed, and the possible implications of...

  15. Physico-chemical characteristics of the ground water table after monsoon: a case study at central Travancore in Kerala

    Directory of Open Access Journals (Sweden)

    Sankar S Vishnu

    2014-05-01

    Full Text Available Water quality plays an important role in maintaining plant and animal life. Lack of good quality drinking water and water for sanitation cause health problems. Water quality characteristics arise from a group of physical, chemical and biological factors. The dynamic balance of the aquatic system can be destroyed by human activities resulting in water pollution.Well water has traditionally considered as a safe resource of water for consumption without treatment and extensively used for individual water supply in rural and many urban areas.In this paper a preliminary analysis is done to explore the water quality of selected wells in order to correlate the effect of pollution on water quality at these locations. Water samples are collected from different regions of Vazhappally area located on central travancore of Kerala. These sites are important because people depend only on well water for drinking purpose. The samples are collected from ten locations and analyzed for chemical parameters such as pH, conductivity, salinity, turbidity, acidity, alkainity, hardness, total phosphates, dissolved oxygen, biological oxygen demand, total dissolved solids and Iron content. Samples are also analysed for coliform bacteria which cause pathogenic diseases. Remarkable differences are observed mainly in biological oxygen demand, acidity and hardness. Finally, an attempt has been done to correlate the observed chemical parameters and the waterquality standards. DOI: http://dx.doi.org/10.3126/ije.v3i2.10501 International Journal of the Environment Vol.3(2 2014: 20-27

  16. Modelling stable water isotopes: Status and perspectives

    Directory of Open Access Journals (Sweden)

    Werner M.

    2010-12-01

    Full Text Available Modelling of stable water isotopes H2 18O and HDO within various parts of the Earth’s hydrological cycle has clearly improved our understanding of the interplay between climatic variations and related isotope fractionation processes. In this article key principles and major research results of stable water isotope modelling studies are described. Emphasis is put on research work using explicit isotope diagnostics within general circulation models as this highly complex model setup bears many resemblances with studies using simpler isotope modelling approaches.

  17. Cache County Water Demand/Supply Model

    OpenAIRE

    Hughes, Trevor C.; Norby, Gregory J.; Thyagarajan, Laxman

    1996-01-01

    This report descibes a municipal water demand forecasting model for use in areas of mixed rural and urban housing types. A series of residential demand functions were derived which forecast water demand based on the ype and density of housing and season. Micro sampling techniques were used to correlate water use data and explanatory variable data for low, medium, and high density housing. The demand functions were...

  18. Multiregional input-output model for the evaluation of Spanish water flows.

    Science.gov (United States)

    Cazcarro, Ignacio; Duarte, Rosa; Sánchez Chóliz, Julio

    2013-01-01

    We construct a multiregional input-output model for Spain, in order to evaluate the pressures on the water resources, virtual water flows, and water footprints of the regions, and the water impact of trade relationships within Spain and abroad. The study is framed with those interregional input-output models constructed to study water flows and impacts of regions in China, Australia, Mexico, or the UK. To build our database, we reconcile regional IO tables, national and regional accountancy of Spain, trade and water data. Results show an important imbalance between origin of water resources and final destination, with significant water pressures in the South, Mediterranean, and some central regions. The most populated and dynamic regions of Madrid and Barcelona are important drivers of water consumption in Spain. Main virtual water exporters are the South and Central agrarian regions: Andalusia, Castile-La Mancha, Castile-Leon, Aragon, and Extremadura, while the main virtual water importers are the industrialized regions of Madrid, Basque country, and the Mediterranean coast. The paper shows the different location of direct and indirect consumers of water in Spain and how the economic trade and consumption pattern of certain areas has significant impacts on the availability of water resources in other different and often drier regions.

  19. Water

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2010-08-01

    Full Text Available Water scarcity is without a doubt on of the greatest threats to the human species and has all the potential to destabilise world peace. Falling water tables are a new phenomenon. Up until the development of steam and electric motors, deep groudwater...

  20. Classical interaction model for the water molecule.

    Science.gov (United States)

    Baranyai, András; Bartók, Albert

    2007-05-14

    The authors propose a new classical model for the water molecule. The geometry of the molecule is built on the rigid TIP5P model and has the experimental gas phase dipole moment of water created by four equal point charges. The model preserves its rigidity but the size of the charges increases or decreases following the electric field created by the rest of the molecules. The polarization is expressed by an electric field dependent nonlinear polarization function. The increasing dipole of the molecule slightly increases the size of the water molecule expressed by the oxygen-centered sigma parameter of the Lennard-Jones interaction. After refining the adjustable parameters, the authors performed Monte Carlo simulations to check the ability of the new model in the ice, liquid, and gas phases. They determined the density and internal energy of several ice polymorphs, liquid water, and gaseous water and calculated the heat capacity, the isothermal compressibility, the isobar heat expansion coefficients, and the dielectric constant of ambient water. They also determined the pair-correlation functions of ambient water and calculated the energy of the water dimer. The accuracy of theirs results was satisfactory.

  1. A Tiled-Table Convention for Compressing FITS Binary Tables

    CERN Document Server

    Pence, William; White, Richard L

    2012-01-01

    This document describes a convention for compressing FITS binary tables that is modeled after the FITS tiled-image compression method (White et al. 2009) that has been in use for about a decade. The input table is first optionally subdivided into tiles, each containing an equal number of rows, then every column of data within each tile is compressed and stored as a variable-length array of bytes in the output FITS binary table. All the header keywords from the input table are copied to the header of the output table and remain uncompressed for efficient access. The output compressed table contains the same number and order of columns as in the input uncompressed binary table. There is one row in the output table corresponding to each tile of rows in the input table. In principle, each column of data can be compressed using a different algorithm that is optimized for the type of data within that column, however in the prototype implementation described here, the gzip algorithm is used to compress every column.

  2. Numerical modeling of water waves

    CERN Document Server

    Lin, Pengzhi

    2008-01-01

    Modelling large-scale wave fields and their interaction with coastal and offshore structures has become much more feasible over the last two decades with increases in computer speeds. Wave modelling can be viewed as an extension of wave theory, a mature and widely published field, applied to practical engineering through the use of computer tools. Information about the various wave models which have been developed is often widely scattered in the literature, and consequently this is one of the first books devoted to wave models and their applications. At the core of the book is an introduction to various types of wave models. For each model, the theoretical assumptions, the application range, and the advantages and limitations are elaborated. The combined use of different wave models from large-scale to local-scale is highlighted with a detailed discussion of the application and matching of boundary conditions. At the same time the book provides a grounding in hydrodynamics, wave theory, and numerical methods...

  3. Estimation of water requirements and Kc values of 'Thompson Seedless' table grapes grown in the overhead trellis system, using the Eddy covariance method

    Directory of Open Access Journals (Sweden)

    Paulina Villagra

    2014-04-01

    Full Text Available Crop evapotranspiration (ETc is essential for irrigation scheduling. The amount of water consumed can be estimated by multiplying the reference evapotranspiration (ET0 by a crop coefficient (Kc; the value of Kc is usually obtained from FAO Paper nr 56. In table grapes (Vitis vinifera L., Kc are obtained from experiments in vines trained on trellis systems; however in Chile, the most used is the overhead trellis system (parronal. Therefore, the objective was to determine water requirements and Kc values of a table grape orchard cv. Thompson Seedless trained on an overhead trellis system in Calle Larga (32°52'40" S, 70°37'45" W, 795 m a.s.l., Aconcagua Valley, Chile, using the Eddy covariance method. During the 2008/2009 and 2009/2010 seasons, the instruments required for ET0 and ETc measurement were installed on a 4 m tower above the soil (2 m above vine canopy. The ET0 was estimated according to the FAO Penman-Monteith equation and ETc by the Eddy covariance method. The Kc was obtained by ratio between ETc and ET0. The maximum ETc was 7 mm d-1 and total water consumption was 810 mm. The season maximum Kc value of 1.2 was obtained near harvest during the first season, and 20 d before veraison in the second season. The Kc increased linearly with the percentage of intercepted solar radiation (IRS by the vine canopy at noon, suggesting that an equation to convert the IRS to Kc is more useful than Kc tabulated according to phenology. The equation obtained in this experiment was Kc = 0.012 IRS - 0.1029, R² = 0.85.

  4. Root water uptake as simulated by three water flow models

    NARCIS (Netherlands)

    Willigen, de P.; Dam, van J.C.; Javaux, M.; Heinen, M.

    2012-01-01

    The objective of our study was to determine to what extent four root water uptake (RWU) models differed when tested under extreme conditions. Cumulative transpiration patterns were similar, contrary to the spatial extraction patterns. The analysis showed that both soil physical and root physiologica

  5. A new pattern of the periodic table

    Directory of Open Access Journals (Sweden)

    Brajendra Nath Tripathi

    1962-07-01

    Full Text Available A new pattern of the Periodic Table is described which incorporates all the points for which various models of two or three dimensional tables have been proposed from time to time.

  6. Code for the steam tables for pure water in visual basic 6.0.; Un codigo para las tablas de vapor para agua pura en visual basic 6.0

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Mahendra P. [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2002-07-01

    The thermodynamic data of the water are of extreme importance in all of the branches of science and technology; the facilitate the understanding of the natural Earth processes. Nevertheless, for the electrical industry the water plays a very important role during the generation of electrical energy process. Different heat sources such as coal, oil, natural gas, nuclear fuel or the geothermal heat boil the water that forms the steam used to move the turbines. Consequently, the steam tables (the thermodynamic water data) are vital to model thermal and mass transference and physical-chemical processes during the generation of electrical energy. [Spanish] Los datos termodinamicos del agua son de suma importancia en todas las ramas de la ciencia y tecnologia, ellos facilitan el entendimiento de los procesos naturales de la Tierra. Sin embargo, para la industria electrica el agua juega un papel muy importante durante el proceso de generacion de energia electrica. Diferentes fuentes de calor tales como carbon, aceite, gas natural, combustible nuclear o el calor geotermico calientan el agua que forma el vapor utilizado para mover las turbinas. Luego entonces, las tablas de vapor (los datos termodinamicos de agua) son vitales para modelar transferencia termica y de masa y procesos fisico-quimico durante la generacion energia electrica.

  7. Microbial and metabolic profiling reveal strong influence of water table and land-use patterns on classification of degraded tropical peatlands

    Directory of Open Access Journals (Sweden)

    S. Mishra

    2013-08-01

    Full Text Available Tropical peatlands from Southeast Asia are undergoing extensive drainage, deforestation and degradation for agriculture and human settlement purposes. This is resulting in biomass loss and subsidence of peat from its oxidation. Molecular profiling approaches were used to understand the relative influences of different land-use patterns, hydrological and physiochemical parameters on the state of degraded tropical peatlands. As microbial communities play a critical role in biogeochemical cascades in the functioning of peatlands, we used microbial and metabolic profiles as surrogates of community structure and functions, respectively. Profiles were generated from 230 bacterial 16S rDNA fragments and 145 metabolic markers of 46 samples from ten sites, including those from above and below water table in a contiguous area of 48 km2 covering five land-use types. These were degraded forest, degraded land, oil palm plantation, mixed crop plantation and settlements. Bacterial profiles were most influenced by variations in water table and land-use patterns, followed by age of drainage and peat thickness in that order. Bacterial profiling revealed differences in sites, based on the duration and frequency of water table fluctuations and on oxygen availability. Bacterial and metabolic profiles of degraded forest and mixed crop plantations were most diverse compared to other land-use types. Metabolic profiling, being closely associated with biogeochemical functions could distinguish communities not only based on land-use types but also their geographic locations, thus providing a finer resolution than bacterial profiles. Agricultural inputs, such as nitrates were highly associated with bacterial community structure of oil palm plantations, whereas phosphates and dissolved organic carbon influenced those from mixed crop plantations and settlements. Our results provide a basis for adopting molecular marker-based approaches to classify peatlands and determine

  8. Development of Ensemble Model Based Water Demand Forecasting Model

    Science.gov (United States)

    Kwon, Hyun-Han; So, Byung-Jin; Kim, Seong-Hyeon; Kim, Byung-Seop

    2014-05-01

    In recent years, Smart Water Grid (SWG) concept has globally emerged over the last decade and also gained significant recognition in South Korea. Especially, there has been growing interest in water demand forecast and optimal pump operation and this has led to various studies regarding energy saving and improvement of water supply reliability. Existing water demand forecasting models are categorized into two groups in view of modeling and predicting their behavior in time series. One is to consider embedded patterns such as seasonality, periodicity and trends, and the other one is an autoregressive model that is using short memory Markovian processes (Emmanuel et al., 2012). The main disadvantage of the abovementioned model is that there is a limit to predictability of water demands of about sub-daily scale because the system is nonlinear. In this regard, this study aims to develop a nonlinear ensemble model for hourly water demand forecasting which allow us to estimate uncertainties across different model classes. The proposed model is consist of two parts. One is a multi-model scheme that is based on combination of independent prediction model. The other one is a cross validation scheme named Bagging approach introduced by Brieman (1996) to derive weighting factors corresponding to individual models. Individual forecasting models that used in this study are linear regression analysis model, polynomial regression, multivariate adaptive regression splines(MARS), SVM(support vector machine). The concepts are demonstrated through application to observed from water plant at several locations in the South Korea. Keywords: water demand, non-linear model, the ensemble forecasting model, uncertainty. Acknowledgements This subject is supported by Korea Ministry of Environment as "Projects for Developing Eco-Innovation Technologies (GT-11-G-02-001-6)

  9. Incorporation of salinity in Water Availability Modeling

    Science.gov (United States)

    Wurbs, Ralph A.; Lee, Chihun

    2011-10-01

    SummaryNatural salt pollution from geologic formations in the upper watersheds of several large river basins in the Southwestern United States severely constrains the use of otherwise available major water supply sources. The Water Rights Analysis Package modeling system has been routinely applied in Texas since the late 1990s in regional and statewide planning studies and administration of the state's water rights permit system, but without consideration of water quality. The modeling system was recently expanded to incorporate salinity considerations in assessments of river/reservoir system capabilities for supplying water for environmental, municipal, agricultural, and industrial needs. Salinity loads and concentrations are tracked through systems of river reaches and reservoirs to develop concentration frequency statistics that augment flow frequency and water supply reliability metrics at pertinent locations for alternative water management strategies. Flexible generalized capabilities are developed for using limited observed salinity data to model highly variable concentrations imposed upon complex river regulation infrastructure and institutional water allocation/management practices.

  10. TABLE 1

    African Journals Online (AJOL)

    BASIS CRISP CRISP

    outbreaks of water associated diseases, especially cholera, that affect the local community periodically. ... diseases that are transmitted by drinking contaminated water such as cholera, dysentery, and ... malfunctioning of the sewage treatment,.

  11. Simple physics-based models of compensatory plant water uptake: concepts and eco-hydrological consequences

    Directory of Open Access Journals (Sweden)

    N. J. Jarvis

    2011-11-01

    Full Text Available Many land surface schemes and simulation models of plant growth designed for practical use employ simple empirical sub-models of root water uptake that cannot adequately reflect the critical role water uptake from sparsely rooted deep subsoil plays in meeting atmospheric transpiration demand in water-limited environments, especially in the presence of shallow groundwater. A failure to account for this so-called "compensatory" water uptake may have serious consequences for both local and global modeling of water and energy fluxes, carbon balances and climate. Some purely empirical compensatory root water uptake models have been proposed, but they are of limited use in global modeling exercises since their parameters cannot be related to measurable soil and vegetation properties. A parsimonious physics-based model of uptake compensation has been developed that requires no more parameters than empirical approaches. This model is described and some aspects of its behavior are illustrated with the help of example simulations. These analyses demonstrate that hydraulic lift can be considered as an extreme form of compensation and that the degree of compensation is principally a function of soil capillarity and the ratio of total effective root length to potential transpiration. Thus, uptake compensation increases as root to leaf area ratios increase, since potential transpiration depends on leaf area. Results of "scenario" simulations for two case studies, one at the local scale (riparian vegetation growing above shallow water tables in seasonally dry or arid climates and one at a global scale (water balances across an aridity gradient in the continental USA, are presented to illustrate biases in model predictions that arise when water uptake compensation is neglected. In the first case, it is shown that only a compensated model can match the strong relationships between water table depth and leaf area and transpiration observed in riparian forest

  12. Simple physics-based models of compensatory plant water uptake: concepts and eco-hydrological consequences

    Directory of Open Access Journals (Sweden)

    N. J. Jarvis

    2011-07-01

    Full Text Available Many land surface schemes and simulation models of plant growth designed for practical use employ simple empirical sub-models of root water uptake that cannot adequately reflect the critical role water uptake from sparsely rooted deep subsoil plays in meeting atmospheric transpiration demand in water-limited environments, especially in the presence of shallow groundwater. A failure to account for this so-called "compensatory" water uptake may have serious consequences for both local and global modeling of water and energy fluxes, carbon balances and climate. Some purely empirical compensatory root water uptake models have been proposed, but they are of limited use in global modeling exercises since their parameters cannot be related to measurable soil and vegetation properties. Parsimonious physics-based models of uptake compensation have been developed that require no more parameters than empirical approaches. These models are described and compared from a conceptual point of view and some aspects of their behavior, including the phenomenon of hydraulic lift, are illustrated with the help of example simulations. These analyses demonstrate that the degree of compensation is a function of soil capillarity and the ratio of total effective root length to potential transpiration. Thus, uptake compensation increases as root to leaf area ratios increase, since potential transpiration depends on leaf area. Results of "scenario" simulations for two case studies, one at the local scale (riparian vegetation growing above shallow water tables in seasonally dry or arid climates and one at a global scale (water balances across an aridity gradient in the continental USA, are presented to illustrate biases in model predictions that arise when water uptake compensation is neglected. In the first case, it is shown that only a compensated model can match the strong relationships between water table depth and leaf area and transpiration observed in riparian forest

  13. 蒸渗仪地下水位自动平衡系统设计%An automatic balancing system design to ground water table of lysimeter

    Institute of Scientific and Technical Information of China (English)

    郭相平; 陆红飞; 陈盛

    2014-01-01

    为准确保持大田水位与蒸渗仪水位的实时相平,并测定地下水补给量和深层渗漏量,提出了一种蒸渗仪水位自动平衡系统的设计方法。该系统基于连通器原理,并利用水、汞的导电性差异而设计,由3部分组成:淤水位监测装置,包括蒸渗仪和大田的地下水位观测井及连接管;于水位感应和控制装置,由内盛液态汞的U形管以及控制电路组成,能比较大田和蒸渗仪的水位差,并通过电磁继电器打开/关闭供排水电磁阀;盂供(排)水与量测装置,由供水装置、排水装置及其电磁阀和量测装置组成。该系统结构简单,造价低廉,易于维护和管理;初步测试表明,该系统具有较好的控制精度,适于地下水位变化较大的地区使用。%In order to synchronize the water table of a lysimeter with that of farmland, and measure the amount of recharge of groundwater and deep percolation, a design method for an automatic balancing system of the water table of a lysimeter is put forward. Based on the principle of a communicating vessel, and designed according to the electrical conductivity differences between water and mercury, the system consists of three parts:(1) water level detecting equipment, consisting of two observation wells and connecting pipes, (2) a water level sensor and controlling equipment, composed of a U-shape glass filled with mercury and control circuits, which can compare the difference of groundwater level between farmland and a lysimeter, and can switch on/off solenoid valves for water supply and drainage through electromagnetic relays; and (3) various equipment, including water supply and drainage equipment, solenoid valves, and measurement devices. The system is simple in construction, cheap, and easy to maintain and manage. The initial testing results indicate that the system has good accuracy, and is appropriate for application in areas where the water table varies

  14. Modeling the Water Balloon Slingshot

    Science.gov (United States)

    Bousquet, Benjamin D.; Figura, Charles C.

    2013-01-01

    In the introductory physics courses at Wartburg College, we have been working to create a lab experience focused on the scientific process itself rather than verification of physical laws presented in the classroom or textbook. To this end, we have developed a number of open-ended modeling exercises suitable for a variety of learning environments,…

  15. Emergence of Tables as First-Graders Cope with Modelling Tasks

    Science.gov (United States)

    Peled, Irit; Keisar, Einav

    2015-01-01

    In this action research, first-graders were challenged to cope with a sequence of modelling tasks involving an analysis of given situations and choices of mathematical tools. In the course of the sequence, they underwent a change in the nature of their problem-solving processes and developed modelling competencies. Moreover, during the task…

  16. Physiological and morphological effects of high water tables on early growth of giant reed (Arundo donax), elephant grass (Pennisetum purpureum), energycane and sugarcane (Saccharum spp.)

    Energy Technology Data Exchange (ETDEWEB)

    Jennewein, Stephen Peter [Univ. of Florida, Gainesville, FL (United States)

    2013-01-01

    Here, an increasing demand for renewable energy sources has spurred interest in high-biomass crops used for energy production. Species potentially well-suited for biofuel production in the seasonally wet organic Everglades Agricultural Area (EAA) of Florida include giant reed (Arundo donax), elephant grass (Pennisetum Purpureum), energycane (Saccharum spp.), and sugarcane (Saccharum spp.). The objectives in this study were to evaluate the role of fluctuating water tables on the morphology, physiology, and early season growth of these four genotypes. The candidate genotypes were grown in a greenhouse under three water table depths, defined by distance of the water table from the soil surface: two constant water tables (-16 cm and -40 cm) along with a flood cycle (2 weeks of flood to the soil level followed by 2 weeks at -40 cm from the soil level). The genotypes included CP 89-2143 (sugarcane), L 79-1002 (energycane), Merkeron (elephant grass), and wild type (giant reed). The experiment was repeated for plant cane, first ratoon, and successive plant cane crop cycles. Reductions in dry matter yield were observed among genotypes subjected to the -40 cm drained, periodically flooded (40F) water table relative to the -40 cm constant (40C) or -16 cm constant (16C). Plant cane dry weights were reduced by 37% in giant reed, 52% in elephant grass, 42% in energycane, and 34% in sugarcane in the 40F compared to 40C water table treatments. Similarly, in the first ratoon crop dry weights were reduced by 29% in giant reed, 42% in elephant grass, 27% in energycane, and 62% in sugarcane. In plant cane and successive plant cane, average total dry weight was greatest for elephant grass whereas ratoon total dry weight was greatest for energycane. Genotype had more pronounced effects on physiological attributes than water table including the highest stomatal conductance and SPAD values in giant reed, and the highest stalk populations in elephant grass and

  17. Stable isotope and noble gas constraints on the source and residence time of spring water from the Table Mountain Group Aquifer, Paarl, South Africa and implications for large scale abstraction

    Science.gov (United States)

    Miller, J. A.; Dunford, A. J.; Swana, K. A.; Palcsu, L.; Butler, M.; Clarke, C. E.

    2017-08-01

    Large scale groundwater abstraction is increasingly being used to support large urban centres especially in areas of low rainfall but presents particular challenges in the management and sustainability of the groundwater system. The Table Mountain Group (TMG) Aquifer is one of the largest and most important aquifer systems in South Africa and is currently being considered as an alternative source of potable water for the City of Cape Town, a metropolis of over four million people. The TMG aquifer is a fractured rock aquifer hosted primarily in super mature sandstones, quartzites and quartz arenites. The groundwater naturally emanates from numerous springs throughout the cape region. One set of springs were examined to assess the source and residence time of the spring water. Oxygen and hydrogen isotopes indicate that the spring water has not been subject to evaporation and in combination with Na/Cl ratios implies that recharge to the spring systems is via coastal precipitation. Although rainfall in the Cape is usually modelled on orographic rainfall, δ18O and δ2H values of some rainfall samples are strongly positive indicating a stratiform component as well. Comparing the spring water δ18O and δ2H values with that of local rainfall, indicates that the springs are likely derived from continuous bulk recharge over the immediate hinterland to the springs and not through large and/or heavy downpours. Noble gas concentrations, combined with tritium and radiocarbon activities indicate that the residence time of the TMG groundwater in this area is decadal in age with a probable maximum upper limit of ∼40 years. This residence time is probably a reflection of the slow flow rate through the fractured rock aquifer and hence indicates that the interconnectedness of the fractures is the most important factor controlling groundwater flow. The short residence time of the groundwater suggest that recharge to the springs and the Table Mountain Group Aquifer as a whole is

  18. The Aerodynamic Plane Table

    Science.gov (United States)

    Zahm, A F

    1924-01-01

    This report gives the description and the use of a specially designed aerodynamic plane table. For the accurate and expeditious geometrical measurement of models in an aerodynamic laboratory, and for miscellaneous truing operations, there is frequent need for a specially equipped plan table. For example, one may have to measure truly to 0.001 inch the offsets of an airfoil at many parts of its surface. Or the offsets of a strut, airship hull, or other carefully formed figure may require exact calipering. Again, a complete airplane model may have to be adjusted for correct incidence at all parts of its surfaces or verified in those parts for conformance to specifications. Such work, if but occasional, may be done on a planing or milling machine; but if frequent, justifies the provision of a special table. For this reason it was found desirable in 1918 to make the table described in this report and to equip it with such gauges and measures as the work should require.

  19. Modeling climate change impacts on water trading.

    Science.gov (United States)

    Luo, Bin; Maqsood, Imran; Gong, Yazhen

    2010-04-01

    This paper presents a new method of evaluating the impacts of climate change on the long-term performance of water trading programs, through designing an indicator to measure the mean of periodic water volume that can be released by trading through a water-use system. The indicator is computed with a stochastic optimization model which can reflect the random uncertainty of water availability. The developed method was demonstrated in the Swift Current Creek watershed of Prairie Canada under two future scenarios simulated by a Canadian Regional Climate Model, in which total water availabilities under future scenarios were estimated using a monthly water balance model. Frequency analysis was performed to obtain the best probability distributions for both observed and simulated water quantity data. Results from the case study indicate that the performance of a trading system is highly scenario-dependent in future climate, with trading effectiveness highly optimistic or undesirable under different future scenarios. Trading effectiveness also largely depends on trading costs, with high costs resulting in failure of the trading program.

  20. Modelling Viking ERA Water Ice Clouds

    Science.gov (United States)

    Tamppari, L. K.; Wilson, R. J.; Zurek, R. W.; Paige, D. A.

    1999-09-01

    Water ice clouds in the Martian atmosphere are increasingly becoming recognized as a potentially important aspect of the water cycle and potentially potent mechanism for climte change. In particular, it has been suggested that water ice cloud formation can control the extent of the water column (Kahn, 1990). Further, water ice cloud formation may scavenge dust out of the atmosphere and may prevent cross-equatorial water transport, especially in the northern summer (Clancy, 1996). To address these questions, a combintion of modelling and data analysis can be used. The Viking era water ice clouds were identified (Tamppari et al., 1998) from the IRTM data set. Following that, Tamppari et al. (1999) attempted to identify the cloud opacity and temperature using a 1D, 2-layer ice and dust cloud model. However, data fits were sensitive to the surface temperature, dust opacity and temperature, and ice particle mode radius value, as well as the water ice cloud temperature and opacity. This resulted in an underconstrained problem. A Mars GCM will be employed to provide realistic atmospheric conditions as a function of season, latitude, and longitude. The non-unit surface emissivities (Christensen, 1998) will be added and synthetic IRTM brightness temperatures will be calculated. Results of the comparison of the synthetic and measured brightness temperatures will be presented.

  1. Modeling and Learning of Complex Motor Tasks: A Case Study with Robot Table Tennis

    OpenAIRE

    Muelling, Katharina

    2013-01-01

    Most tasks that humans need to accomplished in their everyday life require certain motor skills. Although most motor skills seem to rely on the same elementary movements, humans are able to accomplish many different tasks. Robots, on the other hand, are still limited to a small number of skills and depend on well-defined environments. Modeling new motor behaviors is therefore an important research area in robotics. Computational models of human motor control are an essential step to con...

  2. New challenges in integrated water quality modelling

    NARCIS (Netherlands)

    Rode, M.; Arhonditsis, G.; Balin, D.; Kebede, T.; Krysanova, V.; Griensven, A.; Zee, van der S.E.A.T.M.

    2010-01-01

    There is an increasing pressure for development of integrated water quality models that effectively couple catchment and in-stream biogeochemical processes. This need stems from increasing legislative requirements and emerging demands related to contemporary climate and land use changes. Modelling w

  3. Modelling water uptake efficiency of root systems

    Science.gov (United States)

    Leitner, Daniel; Tron, Stefania; Schröder, Natalie; Bodner, Gernot; Javaux, Mathieu; Vanderborght, Jan; Vereecken, Harry; Schnepf, Andrea

    2016-04-01

    Water uptake is crucial for plant productivity. Trait based breeding for more water efficient crops will enable a sustainable agricultural management under specific pedoclimatic conditions, and can increase drought resistance of plants. Mathematical modelling can be used to find suitable root system traits for better water uptake efficiency defined as amount of water taken up per unit of root biomass. This approach requires large simulation times and large number of simulation runs, since we test different root systems under different pedoclimatic conditions. In this work, we model water movement by the 1-dimensional Richards equation with the soil hydraulic properties described according to the van Genuchten model. Climatic conditions serve as the upper boundary condition. The root system grows during the simulation period and water uptake is calculated via a sink term (after Tron et al. 2015). The goal of this work is to compare different free software tools based on different numerical schemes to solve the model. We compare implementations using DUMUX (based on finite volumes), Hydrus 1D (based on finite elements), and a Matlab implementation of Van Dam, J. C., & Feddes 2000 (based on finite differences). We analyse the methods for accuracy, speed and flexibility. Using this model case study, we can clearly show the impact of various root system traits on water uptake efficiency. Furthermore, we can quantify frequent simplifications that are introduced in the modelling step like considering a static root system instead of a growing one, or considering a sink term based on root density instead of considering the full root hydraulic model (Javaux et al. 2008). References Tron, S., Bodner, G., Laio, F., Ridolfi, L., & Leitner, D. (2015). Can diversity in root architecture explain plant water use efficiency? A modeling study. Ecological modelling, 312, 200-210. Van Dam, J. C., & Feddes, R. A. (2000). Numerical simulation of infiltration, evaporation and shallow

  4. Multi-Algorithm Indices and Look-Up Table for Chlorophyll-a Retrieval in Highly Turbid Water Bodies Using Multispectral Data

    Directory of Open Access Journals (Sweden)

    Salem Ibrahim Salem

    2017-06-01

    Full Text Available Many approaches have been proposed for monitoring the eutrophication of Case 2 waters using remote sensing data. Semi-analytical algorithms and spectrum matching are two major approaches for chlorophyll-a (Chla retrieval. Semi-analytical algorithms provide indices correlated with phytoplankton characteristics, (e.g., maximum and minimum absorption peaks. Algorithms’ indices are correlated with measured Chla through the regression process. The main drawback of the semi-analytical algorithms is that the derived relation is location and data limited. Spectrum matching and the look-up table approach rely on matching the measured reflectance with a large library of simulated references corresponding to wide ranges of water properties. The spectral matching approach taking hyperspectral measured reflectance as an input, leading to difficulties in incorporating data from multispectral satellites. Consequently, multi-algorithm indices and the look-up table (MAIN-LUT technique is proposed to combine the merits of semi-analytical algorithms and look-up table, which can be applied to multispectral data. Eight combinations of four algorithms (i.e., 2-band, 3-band, maximum chlorophyll index, and normalized difference chlorophyll index are investigated for the MAIN-LUT technique. In situ measurements and Medium Resolution Imaging Spectrometer (MERIS sensor data are used to validate MAIN-LUT. In general, the MAIN-LUT provide a comparable retrieval accuracy with locally tuned algorithms. The most accurate of the locally tuned algorithms varied among datasets, revealing the limitation of these algorithms to be applied universally. In contrast, the MAIN-LUT provided relatively high retrieval accuracy for Tokyo Bay (R2 = 0.692, root mean square error (RMSE = 21.4 mg m−3, Lake Kasumigaura (R2 = 0.866, RMSE = 11.3 mg m−3, and MERIS data over Lake Kasumigaura (R2 = 0.57, RMSE = 36.5 mg m−3. The simulated reflectance library of MAIN-LUT was generated based on

  5. 2010 Water-Table Contours of the Mojave River and the Morongo Groundwater Basins, San Bernardino County, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — During 2010, the U.S. Geological Survey and other agencies made approximately 2,500 water-level measurements in the Mojave River and Morongo groundwater basins....

  6. 40 CFR Table 1 to Subpart IIIi of... - Emission Standards for Stationary Pre-2007 Model Year Engines With a Displacement of

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Emission Standards for Stationary Pre-2007 Model Year Engines With a Displacement of 1 Table 1 to Subpart IIII of Part 60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards...

  7. The Community Water Model (CWATM) / Development of a community driven global water model

    Science.gov (United States)

    Burek, Peter; Satoh, Yusuke; Greve, Peter; Kahil, Taher; Wada, Yoshihide

    2017-04-01

    With a growing population and economic development, it is expected that water demands will increase significantly in the future, especially in developing regions. At the same time, climate change is expected to alter spatial patterns of hydrological cycle and will have global, regional and local impacts on water availability. Thus, it is important to assess water supply, water demand and environmental needs over time to identify the populations and locations that will be most affected by these changes linked to water scarcity, droughts and floods. The Community Water Model (CWATM) will be designed for this purpose in that it includes an accounting of how future water demands will evolve in response to socioeconomic change and how water availability will change in response to climate. CWATM represents one of the new key elements of IIASA's Water program. It has been developed to work flexibly at both global and regional level at different spatial resolutions. The model is open source and community-driven to promote our work amongst the wider water community worldwide and is flexible enough linking to further planned developments such as water quality and hydro-economic modules. CWATM will be a basis to develop a next-generation global hydro-economic modeling framework that represents the economic trade-offs among different water management options over a basin looking at water supply infrastructure and demand managements. The integrated modeling framework will consider water demand from agriculture, domestic, energy, industry and environment, investment needs to alleviate future water scarcity, and will provide a portfolio of economically optimal solutions for achieving future water management options under the Sustainable Development Goals (SDG) for example. In addition, it will be able to track the energy requirements associated with the water supply system e.g., pumping, desalination and interbasin transfer to realize the linkage with the water-energy economy. In

  8. Wave Numerical Model for Shallow Water

    Institute of Scientific and Technical Information of China (English)

    徐福敏; 严以新; 张长宽; 宋志尧; 茅丽华

    2000-01-01

    The history of forecasting wind waves by wave energy conservation equation is briefly described. Several currently used wave numerical models for shallow water based on different wave theories are discussed. Wave energy conservation models for the simulation of shallow water waves are introduced,with emphasis placed on the SWAN model, which takes use of the most advanced wave research achievements and has been applied to several theoretical and field conditions. The characteristics and applicability of the model, the finite difference numerical scheme of the action balance equation and its source terms computing methods are described in detail. The model has been verified with the propagation refraction numerical experiments for waves propagating in following and opposing currents; finally, the model is applied to the Haian Gulf area to simulate the wave height and wave period field there, and the results are compared with observed data.

  9. Variational modelling of nonlinear water waves

    Science.gov (United States)

    Kalogirou, Anna; Bokhove, Onno

    2015-11-01

    Mathematical modelling of water waves is demonstrated by investigating variational methods. A potential flow water wave model is derived using variational techniques and extented to include explicit time-dependence, leading to non-autonomous dynamics. As a first example, we consider the problem of a soliton splash in a long wave channel with a contraction at its end, resulting after a sluice gate is removed at a finite time. The removal of the sluice gate is included in the variational principle through a time-dependent gravitational potential. A second example involving non-autonomous dynamics concerns the motion of a free surface in a vertical Hele-Shaw cell. Explicit time-dependence now enters the model through a linear damping term due to the effect of wall friction and a term representing the motion of an artificially driven wave pump. In both cases, the model is solved numerically using a Galerkin FEM and the numerical results are compared to wave structures observed in experiments. The water wave model is also adapted to accommodate nonlinear ship dynamics. The novelty is this case is the coupling between the water wave dynamics, the ship dynamics and water line dynamics on the ship. For simplicity, we consider a simple ship structure consisting of V-shaped cross-sections.

  10. A convenient method and numerical tables for sample size determination in longitudinal-experimental research using multilevel models.

    Science.gov (United States)

    Usami, Satoshi

    2014-12-01

    Recent years have shown increased awareness of the importance of sample size determination in experimental research. Yet effective and convenient methods for sample size determination, especially in longitudinal experimental design, are still under development, and application of power analysis in applied research remains limited. This article presents a convenient method for sample size determination in longitudinal experimental research using a multilevel model. A fundamental idea of this method is transformation of model parameters (level 1 error variance [σ(2)], level 2 error variances [τ 00, τ 11] and its covariance [τ 01, τ 10], and a parameter representing experimental effect [δ]) into indices (reliability of measurement at the first time point [ρ 1], effect size at the last time point [Δ T ], proportion of variance of outcomes between the first and the last time points [k], and level 2 error correlation [r]) that are intuitively understandable and easily specified. To foster more convenient use of power analysis, numerical tables are constructed that refer to ANOVA results to investigate the influence on statistical power by respective indices.

  11. A Water Management Model for Toshka Depression

    Directory of Open Access Journals (Sweden)

    K. M. Fassieh

    2014-01-01

    Full Text Available Toshka Depression (TD, located about 250 km south west of the High Aswan Dam (HAD, consists of four deep-cut basins connected by natural sills. It is required to assess the contribution of TD as a spillway, in enhancing the effectiveness of Lake Nasser in flood control and water availability. However, most related previous works are descriptive and use qualitative methods. In order to provide the required assessment quantitatively, we developed a numerical model which computes TD mass balance and interbasin water movements. The model computes the variation of water volume, surface area, and water level in each one of the four basins (subdepressions, thus depicting their filling sequence, for the past 130 years. This TD response to realistic time series of water inflow gains and evaporation losses is analyzed to compute the TD overflow time series. This response helps assess water availability for agricultural use and effectiveness in alleviating flood risks. Furthermore, the developed model compares between three TD configurations to help the decision maker and recommends (i building a dam—height 10 m—at the end of the fourth subdepression near Kharga Oasis and/or (ii incorporating the third subdepression into TD by digging a canal through the hill that blocks it from the first subdepression.

  12. Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    P. Tucci

    2001-12-20

    This Analysis/Model Report (AMR) documents an updated analysis of water-level data performed to provide the saturated-zone, site-scale flow and transport model (CRWMS M&O 2000) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for model calibration. The previous analysis was presented in ANL-NBS-HS-000034, Rev 00 ICN 01, Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (USGS 2001). This analysis is designed to use updated water-level data as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain. The objectives of this revision are to develop computer files containing (1) water-level data within the model area (DTN: GS010908312332.002), (2) a table of known vertical head differences (DTN: GS0109083 12332.003), and (3) a potentiometric-surface map (DTN: GS010608312332.001) using an alternate concept from that presented in ANL-NBS-HS-000034, Rev 00 ICN 01 for the area north of Yucca Mountain. The updated water-level data include data obtained from the Nye County Early Warning Drilling Program (EWDP) and data from borehole USW WT-24. In addition to being utilized by the SZ site-scale flow and transport model, the water-level data and potentiometric-surface map contained within this report will be available to other government agencies and water users for ground-water management purposes. The potentiometric surface defines an upper boundary of the site-scale flow model, as well as provides information useful to estimation of the magnitude and direction of lateral ground-water flow within the flow system. Therefore, the analysis documented in this revision is important to SZ flow and transport calculations in support of total system performance assessment.

  13. Impact of water table depth and shallow groundwater use on salt leaching cycle in irrigated areas%灌区地下水控制埋深与利用量对洗盐周期的影响

    Institute of Scientific and Technical Information of China (English)

    李山; 罗纨; 贾忠华; 潘延鑫; 武迪

    2014-01-01

    灌区地下水位调控可增加作物对浅层地下水的利用量,但当地下水含盐量较高时,作物对其利用会加快盐分在根区的累积速度,进而影响灌溉淋洗制度。本文根据农田水盐平衡的基本原理,考虑不同埋深的浅层地下水利用条件下根区土壤盐分的累积过程,建立了土壤盐分淋洗周期的理论模型,并根据两组试验数据进行了应用分析。计算结果显示,位于半干旱区的研究区,地下水含盐量4.43 g/L,埋深维持在1 m和1.5 m时,多年平均降雨条件下,棉花生长期内需要排水洗盐的周期分别为100 d 和140 d;埋深大于2 m 时,淋洗周期超过了生长期。另一研究区位于干旱区,滴灌棉田地下水埋深为1.5 m时,用含盐量为2.81 g/L的微咸水进行滴灌,棉花生长期内需要排水淋洗的时间为78 d左右。因此,即使在灌区水位调控抬高地下水位后,在一个生长周期内,根区土壤盐分的增长过程仍然相对缓慢,为灌区制定淋洗制度提供了时间窗口。%Water table management in irrigated areas may increase shallow groundwater use by crops. But the high salt content of groundwater results in faster buildup of salinity in crop root zone,which in turn af-fects leaching schedule of the irrigation districts. Based on general salt and water balance in crop fields in irrigated areas, a simplified model was proposed in this paper to calculate leaching cycle for crops that use shallow groundwater at different water table depth, considering the salt accumulation process in root zone of crops. Subsequently, leaching cycles were calculated for two study sites with soil salinity measure-ments. For the case study in a semi-arid irrigation area,under the current irrigation scheduling and the av-erage rainfall condition, the calculated leaching cycle for cotton fields is 100 days for water table depth at 1 m and 140 days for water table depth at 1.5 m with the

  14. Analyzing and Improving the Water-Table Fluctuation Method of Estimating Groundwater Recharge: Field Considerations Patros, T.B. and Parkin, G.W., School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada

    Science.gov (United States)

    Patros, T.; Parkin, G. W.

    2012-12-01

    The focus of the project is on measuring and quantifying groundwater recharge (GWR) using the water-table fluctuation (WTF) method. This method requires measuring the change in water-table (WT) height (Δh) during recharge (R) events and volumetric soil specific yield water content (θsy), (&/or) perhaps more correctly volumetric soil fillable water content (θf). The rise in WT can also result from other non-precipitation-related WTF causes (e.g., Lisse effect, temperature variations, barometric, lateral flow, Reverse Wieringermeer effect, encapsulated air, pumping), which must be counted for. The measurement of the storativity (S) terms (θsy) and/or θf) is, indeed, not clear-cut and often they are taken as being constant with depth, time, WT movement (Drying-Wetting & Freezing-Thawing) history and heterogeneity. In fact, these two terms (θsy & θf) are controversial in their definition, thus in their use, in the literature and may either overestimate the R, when using θsy, or underestimate it, when using θf. To resolve some of these questions, a novel-automated method is under development, at the University of Guelph's Elora Research Station (ERS) and Arboretum, along with a novel multi-event time series model. The long-term expected outcomes and significance of this study are; 1. Establishing accuracy in defining and evaluating the θsy and θf and using them accordingly in estimating GWR with the WTF method in order to overcome some of the existing substantial gaps in our knowledge of groundwater (GW) storage variation. 2. Obtaining GWR measurements at the local scale on a year-round basis, which are currently scarce or even completely lacking for many regions of Ontario and thus would provide a valuable database for guiding development of any policy requiring GWR. 3. Using this database to calibrate and test estimates of the spatial and temporal variability in regional-scale (watershed scale) GWR from approximate statistical techniques or deterministic

  15. Water quality modelling of Lis River, Portugal.

    Science.gov (United States)

    Vieira, Judite; Fonseca, André; Vilar, Vítor J P; Boaventura, Rui A R; Botelho, Cidália M S

    2013-01-01

    The aim of the study was to predict the impact of flow conditions, discharges and tributaries on the water quality of Lis River using QUAL2Kw model. Calibration of the model was performed, based on data obtained in field surveys carried out in July 2004 and November 2006. Generally the model fitted quite well the experimental data. The results indicated a decrease of water quality in the downstream area of Lis River, after the confluence of Lena, Milagres and Amor tributaries, as a result of discharges of wastewaters containing degradable organics, nutrients and pathogenic organisms from cattle-raising wastewaters, domestic effluents and agricultural runoff. The water quality criteria were exceeded in these areas for dissolved oxygen, biochemical oxygen demand, total nitrogen and faecal coliforms. Water quality modelling in different scenarios showed that the impact of tributaries on the quality of Lis River water was quite negligible and mainly depends on discharges, which are responsible by an increase of almost 45, 13 and 44 % of ultimate carbonaceous biochemical oxygen demand (CBOD(u)), ammonium nitrogen and faecal coliforms, for winter simulation, and 23, 33 and 36 % for summer simulation, respectively, when compared to the real case scenario.

  16. Water-table altitude of the unconfined aquifer, Wood River Valley aquifer system, south-central Idaho, October 2012.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Water levels in 93 wells completed in the Wood River Valley aquifer system were measured during October 22–24, 2012; these wells are part of a network established...

  17. Assessing HYDRUS-2D model to estimate soil water contents and olive tree transpiration fluxes under different water distribution systems

    Science.gov (United States)

    Autovino, Dario; Negm, Amro; Rallo, Giovanni; Provenzano, Giuseppe

    2016-04-01

    In Mediterranean countries characterized by limited water resources for agricultural and societal sectors, irrigation management plays a major role to improve water use efficiency at farm scale, mainly where irrigation systems are correctly designed to guarantee a suitable application efficiency and the uniform water distribution throughout the field. In the last two decades, physically-based agro-hydrological models have been developed to simulate mass and energy exchange processes in the soil-plant-atmosphere (SPA) system. Mechanistic models like HYDRUS 2D/3D (Šimunek et al., 2011) have been proposed to simulate all the components of water balance, including actual crop transpiration fluxes estimated according to a soil potential-dependent sink term. Even though the suitability of these models to simulate the temporal dynamics of soil and crop water status has been reported in the literature for different horticultural crops, a few researches have been considering arboreal crops where the higher gradients of root water uptake are the combination between the localized irrigation supply and the three dimensional root system distribution. The main objective of the paper was to assess the performance of HYDRUS-2D model to evaluate soil water contents and transpiration fluxes of an olive orchard irrigated with two different water distribution systems. Experiments were carried out in Castelvetrano (Sicily) during irrigation seasons 2011 and 2012, in a commercial farm specialized in the production of table olives (Olea europaea L., var. Nocellara del Belice), representing the typical variety of the surrounding area. During the first season, irrigation water was provided by a single lateral placed along the plant row with four emitters per plant (ordinary irrigation), whereas during the second season a grid of emitters laid on the soil was installed in order to irrigate the whole soil surface around the selected trees. The model performance was assessed based on the

  18. Generation of SEEAW asset accounts based on water resources management models

    Science.gov (United States)

    Pedro-Monzonís, María; Solera, Abel; Andreu, Joaquín

    2015-04-01

    One of the main challenges in the XXI century is related with the sustainable use of water. This is due to the fact that water is an essential element for the life of all who inhabit our planet. In many cases, the lack of economic valuation of water resources causes an inefficient water use. In this regard, society expects of policymakers and stakeholders maximise the profit produced per unit of natural resources. Water planning and the Integrated Water Resources Management (IWRM) represent the best way to achieve this goal. The System of Environmental-Economic Accounting for Water (SEEAW) is displayed as a tool for water allocation which enables the building of water balances in a river basin. The main concern of the SEEAW is to provide a standard approach which allows the policymakers to compare results between different territories. But building water accounts is a complex task due to the difficulty of the collection of the required data. Due to the difficulty of gauging the components of the hydrological cycle, the use of simulation models has become an essential tool extensively employed in last decades. The target of this paper is to present the building up of a database that enables the combined use of hydrological models and water resources models developed with AQUATOOL DSSS to fill in the SEEAW tables. This research is framed within the Water Accounting in a Multi-Catchment District (WAMCD) project, financed by the European Union. Its main goal is the development of water accounts in the Mediterranean Andalusian River Basin District, in Spain. This research pretends to contribute to the objectives of the "Blueprint to safeguard Europe's water resources". It is noteworthy that, in Spain, a large part of these methodological decisions are included in the Spanish Guideline of Water Planning with normative status guaranteeing consistency and comparability of the results.

  19. Modelling of water potential and water uptake rate of tomato plants in the greenhouse: preliminary results.

    NARCIS (Netherlands)

    Bruggink, G.T.; Schouwink, H.E.; Gieling, Th.H.

    1988-01-01

    A dynamic model is presented which predicts water potential and water uptake rate of greenhouse tomato plants using transpiration rate as input. The model assumes that water uptake is the resultant of water potential and hydraulic resistance, and that water potential is linearly related to water con

  20. Uncertainty in surface water flood risk modelling

    Science.gov (United States)

    Butler, J. B.; Martin, D. N.; Roberts, E.; Domuah, R.

    2009-04-01

    Two thirds of the flooding that occurred in the UK during summer 2007 was as a result of surface water (otherwise known as ‘pluvial') rather than river or coastal flooding. In response, the Environment Agency and Interim Pitt Reviews have highlighted the need for surface water risk mapping and warning tools to identify, and prepare for, flooding induced by heavy rainfall events. This need is compounded by the likely increase in rainfall intensities due to climate change. The Association of British Insurers has called for the Environment Agency to commission nationwide flood risk maps showing the relative risk of flooding from all sources. At the wider European scale, the recently-published EC Directive on the assessment and management of flood risks will require Member States to evaluate, map and model flood risk from a variety of sources. As such, there is now a clear and immediate requirement for the development of techniques for assessing and managing surface water flood risk across large areas. This paper describes an approach for integrating rainfall, drainage network and high-resolution topographic data using Flowroute™, a high-resolution flood mapping and modelling platform, to produce deterministic surface water flood risk maps. Information is provided from UK case studies to enable assessment and validation of modelled results using historical flood information and insurance claims data. Flowroute was co-developed with flood scientists at Cambridge University specifically to simulate river dynamics and floodplain inundation in complex, congested urban areas in a highly computationally efficient manner. It utilises high-resolution topographic information to route flows around individual buildings so as to enable the prediction of flood depths, extents, durations and velocities. As such, the model forms an ideal platform for the development of surface water flood risk modelling and mapping capabilities. The 2-dimensional component of Flowroute employs

  1. Nutrient load can lead to enhanced CH4 fluxes through changes in vegetation, peat surface elevation and water table depth in ombrotrophic bog

    Science.gov (United States)

    Juutinen, Sari; Bubier, Jill; Larmola, Tuula; Humphreys, Elyn; Arnkil, Sini; Roy, Cameron; Moore, Tim

    2016-04-01

    Atmospheric nitrogen (N) deposition has led to nutrient enrichment in wetlands, particularly in temperate areas, affecting plant community composition, carbon (C) cycling, and microbial dynamics. It is vital to understand the temporal scales and mechanisms of the changes, because peatlands are long-term sinks of C, but sources of methane (CH4), an important greenhouse gas. Rainwater fed (ombrotrophic) bogs are considered to be vulnerable to nutrient loading due to their natural nutrient poor status. We fertilized Mer Bleue Bog, a Sphagnum moss and evergreen shrub-dominated ombrotrophic bog near Ottawa, Ontario, now for 11-16 years with N (NO3 NH4) at 0.6, 3.2, and 6.4 g N m-2 y-1 (~5, 10 and 20 times ambient N deposition during summer months) with and without phosphorus (P) and potassium (K). Treatments were applied to triplicate plots (3 x 3 m) from May - August 2000-2015 and control plots received distilled water. We measured CH4 fluxes with static chambers weekly from May to September 2015 and peat samples were incubated in laboratory to measure CH4 production and consumption potentials. Methane fluxes at the site were generally low, but after 16 years, mean CH4 emissions have increased and more than doubled in high nitrogen addition treatments if P and K input was also increased (3.2 and 6.4 g N m-2yr-1 with PK), owing to drastic changes in vegetation and soil moisture. Vegetation changes include a loss of Sphagnum moss and introduction of new species, typical to minerogenic mires, which together with increased decomposition have led to decreased surface elevation and to higher water table level relative to the surface. The trajectories indicate that the N only treatments may result in similar responses, but only over longer time scales. Elevated atmospheric deposition of nutrients to peatlands may increase loss of C not only due to changes in CO2 exchange but also due to enhanced CH4 emissions in peatlands through a complex suite of feedbacks and interactions

  2. Interactive Water Resources Modeling and Model Use: An Overview

    Science.gov (United States)

    Loucks, Daniel P.; Kindler, Janusz; Fedra, Kurt

    1985-02-01

    This serves as an introduction for the following sequence of five papers on interactive water resources and environmental management, policy modeling, and model use. We review some important shortcomings of many management and policy models and argue for improved human-computer-model interaction and communication. This interaction can lead to more effective model use which in turn should facilitate the exploration, analysis, and synthesis of alternative designs, plans, and policies by those directly involved in the planning, management, or policy making process. Potential advantages of interactive modeling and model use, as well as some problems and research needs, are discussed.

  3. Global modelling of Cryptosporidium in surface water

    Science.gov (United States)

    Vermeulen, Lucie; Hofstra, Nynke

    2016-04-01

    Introduction Waterborne pathogens that cause diarrhoea, such as Cryptosporidium, pose a health risk all over the world. In many regions quantitative information on pathogens in surface water is unavailable. Our main objective is to model Cryptosporidium concentrations in surface waters worldwide. We present the GloWPa-Crypto model and use the model in a scenario analysis. A first exploration of global Cryptosporidium emissions to surface waters has been published by Hofstra et al. (2013). Further work has focused on modelling emissions of Cryptosporidium and Rotavirus to surface waters from human sources (Vermeulen et al 2015, Kiulia et al 2015). A global waterborne pathogen model can provide valuable insights by (1) providing quantitative information on pathogen levels in data-sparse regions, (2) identifying pathogen hotspots, (3) enabling future projections under global change scenarios and (4) supporting decision making. Material and Methods GloWPa-Crypto runs on a monthly time step and represents conditions for approximately the year 2010. The spatial resolution is a 0.5 x 0.5 degree latitude x longitude grid for the world. We use livestock maps (http://livestock.geo-wiki.org/) combined with literature estimates to calculate spatially explicit livestock Cryptosporidium emissions. For human Cryptosporidium emissions, we use UN population estimates, the WHO/UNICEF JMP sanitation country data and literature estimates of wastewater treatment. We combine our emissions model with a river routing model and data from the VIC hydrological model (http://vic.readthedocs.org/en/master/) to calculate concentrations in surface water. Cryptosporidium survival during transport depends on UV radiation and water temperature. We explore pathogen emissions and concentrations in 2050 with the new Shared Socio-economic Pathways (SSPs) 1 and 3. These scenarios describe plausible future trends in demographics, economic development and the degree of global integration. Results and

  4. Les Tables de salon (Coffee Tables)

    Science.gov (United States)

    Rondina, Marisa; Gilbert, Rodrigue

    1977-01-01

    Terms for such things as furniture in English reflect function and are specific, not generic in nature. French equivalents are based on linguistic criteria. "Tables basses" or "tables de salon" are equivalents of "coffee tables"; they illustrate the tendency toward the generic of the French language. (Text is in French.) (AMH)

  5. A Water-Withdrawal Input-Output Model of the Indian Economy.

    Science.gov (United States)

    Bogra, Shelly; Bakshi, Bhavik R; Mathur, Ritu

    2016-02-02

    Managing freshwater allocation for a highly populated and growing economy like India can benefit from knowledge about the effect of economic activities. This study transforms the 2003-2004 economic input-output (IO) table of India into a water withdrawal input-output model to quantify direct and indirect flows. This unique model is based on a comprehensive database compiled from diverse public sources, and estimates direct and indirect water withdrawal of all economic sectors. It distinguishes between green (rainfall), blue (surface and ground), and scarce groundwater. Results indicate that the total direct water withdrawal is nearly 3052 billion cubic meter (BCM) and 96% of this is used in agriculture sectors with the contribution of direct green water being about 1145 BCM, excluding forestry. Apart from 727 BCM direct blue water withdrawal for agricultural, other significant users include "Electricity" with 64 BCM, "Water supply" with 44 BCM and other industrial sectors with nearly 14 BCM. "Construction", "miscellaneous food products"; "Hotels and restaurants"; "Paper, paper products, and newsprint" are other significant indirect withdrawers. The net virtual water import is found to be insignificant compared to direct water used in agriculture nationally, while scarce ground water associated with crops is largely contributed by northern states.

  6. A computerized coal-water slurry transportation model

    Energy Technology Data Exchange (ETDEWEB)

    Ljubicic, B.R.; Trostad, B. [Univ. of North Dakota, Grand Forks, ND (United States); Bukurov, Z.; Cvijanovic, P. [Univ. of Novi Sad (Yugoslavia)

    1995-12-01

    Coal-water fuel (CWF) technology has been developed to the point where full-scale commercialization is just a matter of gaining sufficient market confidence in the price stability of alternate fossil fuels. In order to generalize alternative fuel cost estimates for the desired combinations of processing and/or transportation, a great deal of flexibility is required owing to the understood lack of precision in many of the newly emerging coal technologies. Previously, decisions regarding the sequential and spatial arrangement of the various process steps were made strictly on the basis of experience, simplified analysis, and intuition. Over the last decade, computer modeling has progressed from empirically based correlation to that of intricate mechanistic analysis. Nomograms, charts, tables, and many simple rules of thumb have been made obsolete by the availability of complex computer models. Given the ability to view results graphically in real or near real time, the engineer can immediately verify, from a practical standpoint, whether the initial assumptions and inputs were indeed valid. If the feasibility of a project is being determined in the context of a lack of specific data, the ability to provide a dynamic software-based solution is crucial. Furthermore, the resulting model can be used to establish preliminary operating procedures, test control logic, and train plant/process operators. Presented in this paper is a computerized model capable of estimating the delivered cost of CWF. The model uses coal-specific values, process and transport requirements, terrain factors, and input costs to determine the final operating configuration, bill of materials, and, ultimately, the capital, operating, and unit costs.

  7. Prediction of hybrid means from a partial circulant diallel table using the ordinary least square and the mixed model methods

    Directory of Open Access Journals (Sweden)

    Américo José dos Santos Reis

    2005-01-01

    Full Text Available By definition, the genetic effects obtained from a circulant diallel table are random. However, because of the methods of analysis, those effects have been considered as fixed. Two different statistical approaches were applied. One assumed the model to be fixed and obtained solutions through the ordinary least square (OLS method. The other assumed a mixed model and estimated the fixed effects (BLUE by generalized least squares (GLS and the best linear unbiased predictor (BLUP of the random effects. The goal of this study was to evaluate the consequences when considering these effects as fixed or random, using the coefficient of correlation between the responses of observed and non-observed hybrids. Crossings were made between S1 inbred lines from two maize populations developed at Universidade Federal de Goiás, the UFG-Samambaia "Dent" and UFG-Samambaia "Flint". A circulant inter-group design was applied, and there were five (s = 5 crossings for each parent. The predictions were made using a reduced model. Diallels with different sizes of s (from 2 to 5 were simulated, and the coefficients of correlation were obtained using two different approaches for each size of s. In the first approach, the observed hybrids were included in both the estimation of the genetic parameters and the coefficient of correlation, while in the second a cross-validation process was employed. In this process, the set of hybrids was divided in two groups: one group, comprising 75% of the original group, to estimate the genetic parameters, and a second one, consisting of the remaining 25%, to validate the predictions. In all cases, a bootstrap process with 200 resamplings was used to generate the empirical distribution of the correlation coefficient. This coefficient showed a decrease as the value of s decreased. The cross-validation method allowed to estimate the bias magnitude in evaluating the correlation coefficient using the same hybrids, to predict the genetic

  8. Pulse radiolysis of liquid water using picosecond electron pulses produced by a table-top terawatt laser system

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, Ned [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Flippo, Kirk [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Nemoto, Koshichi [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Umstadter, Donald [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Crowell, Robert A. [Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Jonah, Charles D. [Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Trifunac, Alexander D. [Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2000-06-01

    A laser based electron generator is shown, for the first time, to produce sufficient charge to conduct time resolved investigations of radiation induced chemical events. Electron pulses generated by focussing terawatt laser pulses into a supersonic helium gas jet are used to ionize liquid water. The decay of the hydrated electrons produced by the ionizing electron pulses is monitored with 0.3 {mu}s time resolution. Hydrated electron concentrations as high as 22 {mu}M were generated. The results show that terawatt lasers offer both an alternative to linear accelerators and a means to achieve subpicosecond time resolution for pulse radiolysis studies. (c) 2000 American Institute of Physics.

  9. Table of 3D organ model IDs and organ names (PART-OF Tree) - BodyParts3D | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available List Contact us BodyParts3D Table of 3D organ model IDs and organ names (PART-OF Tree) Data detail Data name Table of 3D...data contents List of downloadable 3D organ models in a tab-delimited text file format, describing the correspondence between 3D...ata file File name: partof_parts_list_e.txt (PART-OF Tree) File URL: ftp://ftp.biosciencedbc.jp/archive/bodyparts3d.../LATEST/partof_parts_list_e.txt File size: 58 KB Simple search URL http://togodb.biosciencedbc.jp/togodb/view/bodyparts3d...item Description concept id ID of the corresponding FMA (Foundational Model of Anatomy). representation id I

  10. Privatization of tubewells in North China: Determinants and impacts on irrigated area, productivity and the water table

    Science.gov (United States)

    Wang, Jinxia; Huang, Jikun; Huang, Qiuqiong; Rozelle, Scott

    2006-03-01

    Despite the rise in importance of the private sector in the expansion of the use of groundwater in China and the potential implications this might have for production and poverty, little has been written about the effect of these phenomena on northern China’s economy. In examining determinants of tubewell privatization and its impact on producers in northern China, data were collected using a community leader survey, carried out in 448 villages in six provinces in northern China. The results show that since 1990 collective ownership of tubewells has largely been replaced by private ownership. Increasing water scarcity, government grants and bank loans for tubewell investment and the declining investment capacity of China’s local communities have led to the observed change in tubewell ownership patterns. By far, the most important positive effect on income appears to be due to the expansion of newly irrigated area that has been fueled by the rise of private tubewells. Many newly private tubewells also have begun to replace irrigation from surface water sources. While helping increase income and productivity, the rise of private tubewells also has contributed to the fall in groundwater levels.

  11. Hydrodynamic modeling of Singapore's coastal waters: Nesting and model accuracy

    Science.gov (United States)

    Hasan, G. M. Jahid; van Maren, Dirk Sebastiaan; Ooi, Seng Keat

    2016-01-01

    The tidal variation in Singapore's coastal waters is influenced by large-scale, complex tidal dynamics (by interaction of the Indian Ocean and the South China Sea) as well as monsoon-driven low frequency variations, requiring a model with large spatial coverage. Close to the shores, the complex topography, influenced by headlands and small islands, requires a high resolution model to simulate tidal dynamics. This can be achieved through direct nesting or multi-scale nesting, involving multiple model grids. In this paper, we investigate the effect of grid resolution and multi-scale nesting on the tidal dynamics in Singapore's coastal waters, by comparing model results with observations using different statistical techniques. The results reveal that the intermediate-scale model is generally sufficiently accurate (equal to or better than the most refined model), but also that the most refined model is only more accurate when nested in the intermediate scale model (requiring multi-scale nesting). This latter is the result of the complex tidal dynamics around Singapore, where the dominantly diurnal tidal currents are decoupled from the semi-diurnal water level variations. Furthermore, different techniques to quantify model accuracy (harmonic analysis, basic statistics and more complex statistics) are inconsistent in determining which model is more accurate.

  12. Identification, toxicity and control of iodinated disinfection byproducts in cooking with simulated chlor(am)inated tap water and iodized table salt.

    Science.gov (United States)

    Pan, Yang; Zhang, Xiangru; Li, Yu

    2016-01-01

    Chlorine/chloramine residuals are maintained in drinking water distribution systems to prevent microbial contamination and microorganism regrowth. During household cooking processes (e.g., soup making), the residual chlorine/chloramines in tap water may react with the iodide in iodized table salt to form hypoiodous acid, which could react with remaining natural organic matter in tap water and organic matter in food to generate iodinated disinfection byproducts (I-DBPs). However, I-DBPs formed during cooking with chloraminated/chlorinated tap water are almost completely new to researchers. In this work, by adopting precursor ion scan of m/z 127 using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, many new polar I-DBPs formed during cooking with chloraminated/chlorinated tap water were detected and proposed with structures, of which 3-iodo-4-hydroxybenzaldehyde, 3-iodo-4-hydroxybenzoic acid, 3-iodo-4-hydroxy-5-methylbenzoic acid, diiodoacetic acid, 3,5-diiodo-4-hydroxybenzaldehyde, 3,5-diiodo-4-hydroxybenzoic acid, 2,6-diiodo-4-nitrophenol, 2,4-diiodo-6-nitrophenol, and 2,4,6-triiodophenol were confirmed with standard compounds. With the aid of ultra fast liquid chromatography/ion trap-time of flight-mass spectrometry, molecular formula identification of five new I-DBPs (C8H5O4I, C7H4NO4I, C8H5O5I, C7H4NO5I, and C8H6O3I2) was achieved. A developmental toxicity with a recently developed sensitive bioassay was conducted for the newly identified I-DBPs, suggesting that phenolic I-DBPs (except for iodinated carboxyphenols) were about 50-200 times more developmentally toxic than aliphatic I-DBPs. The major I-DBPs in a baseline simulated cooking water sample were determined to be from 0.72 to 7.63 μg/L. Polar I-DBPs formed under various disinfection and cooking conditions were compared, and suggestions for controlling their formation were provided.

  13. Semiempirical model of soil water hysteresis

    Science.gov (United States)

    Nimmo, J.R.

    1992-01-01

    In order to represent hysteretic soil water retention curves accurately using as few measurements as possible, a new semiempirical model has been developed. It has two postulates related to physical characteristics of the medium, and two parameters, each with a definite physical interpretation, whose values are determined empirically for a given porous medium. Tests of the model show that it provides high-quality optimized fits to measured water content vs. matric pressure wetting curves for a wide variety of media. A practical use of this model is to provide a complete simulated main wetting curve for a medium where only a main drying curve and two points on the wetting curve have been measured. -from Author

  14. Polarizable water model for Dissipative Particle Dynamics

    Science.gov (United States)

    Pivkin, Igor; Peter, Emanuel

    2015-11-01

    Dissipative Particle Dynamics (DPD) is an efficient particle-based method for modeling mesoscopic behavior of fluid systems. DPD forces conserve the momentum resulting in a correct description of hydrodynamic interactions. Polarizability has been introduced into some coarse-grained particle-based simulation methods; however it has not been done with DPD before. We developed a new polarizable coarse-grained water model for DPD, which employs long-range electrostatics and Drude oscillators. In this talk, we will present the model and its applications in simulations of membrane systems, where polarization effects play an essential role.

  15. Modeling of Water Movement Near Saturation

    Science.gov (United States)

    Ippisch, O.; Graf, H.; Bastian, P.; Roth, K.

    Water transport in unsaturated porous media is often described using Richards' equa- tion. However Richards' equation is based on the assumption that the gas phase is mobile enough to be always (nearly) at atmospheric pressure. This assumption is not valid if the porous medium is nearly saturated with water. The difference between model calculations using Richards' equation and a multiphase formulation is analyzed and compared to results from multistep outflow experiments with columns of sintered glass. The chosen parameterization for the hydraulic param- eters (van Genuchten/Brooks-Corey) proves to expecially important.

  16. Influence of landscape position and transient water table on soil development and carbon distribution in a steep, headwater catchment

    Science.gov (United States)

    Scott W. Bailey; Patricia A. Brousseau; Kevin J. McGuire; Donald S. Ross

    2014-01-01

    Upland headwater catchments, such as those in the AppalachianMountain region, are typified by coarse textured soils, flashy hydrologic response, and low baseflow of streams, suggesting well drained soils and minimal groundwater storage. Model formulations of soil genesis, nutrient cycling, critical loads and rainfall/runoff response are typically based on vertical...

  17. The National Danish Water Resources Model - using an integrated groundwater - surface water model for decision support and WFD implementation in a changing climate

    Science.gov (United States)

    Lajer Hojberg, Anker; Hinsby, Klaus; Jørgen Henriksen, Hans; Troldborg, Lars

    2014-05-01

    Integrated and sustainable water resources management and development of river basin management plans according to the Water Framework Directive is getting increasingly complex especially when taking projected climate change into account. Furthermore, uncertainty in future developments and incomplete knowledge of the physical system introduces a high degree of uncertainty in the decision making process. Knowledge based decision making is therefore vital for formulation of robust management plans and to allow assessment of the inherent uncertainties. The Department of Hydrology at the Geological Survey of Denmark and Greenland started in 1996 to develop a mechanistically, transient and spatially distributed groundwater-surface water model - the DK-model - for the assessment of groundwater quantitative status accounting for interactions with surface water and anthropogenic changes, such as extraction strategies and land use, as well as climate change. The model has been subject to continuous update building on hydrogeological knowledge established by the regional water authorities and other national research institutes. With the on-going improvement of the DK-model it is now increasingly applied both by research projects and for decision support e.g. in implementation of the Water Framework Directive or to support other decisions related to protection of water resources (quantitative and chemical status), ecosystems and the built environment. At present, the DK-model constitutes the backbone of a strategic modelling project funded by the Danish Environmental Protection Agency, with the aim of developing a modelling complex that will provide the foundation of the implementation of the Water Framework Directive. Since 2003 the DK-model has been used in more than 25 scientific papers and even more public reports. In the poster and the related review paper we describe the most important applications in both science and policy, where the DK-model has been used either

  18. Integrated Water Resources Simulation Model for Rural Community

    Science.gov (United States)

    Li, Y.-H.; Liao, W.-T.; Tung, C.-P.

    2012-04-01

    The purpose of this study is to develop several water resources simulation models for residence houses, constructed wetlands and farms and then integrate these models for a rural community. Domestic and irrigation water uses are the major water demand in rural community. To build up a model estimating domestic water demand for residence houses, the average water use per person per day should be accounted first, including water uses of kitchen, bathroom, toilet and laundry. On the other hand, rice is the major crop in the study region, and its productive efficiency sometimes depends on the quantity of irrigation water. The water demand can be estimated by crop water use, field leakage and water distribution loss. Irrigation water comes from rainfall, water supply system and reclaimed water which treated by constructed wetland. In recent years, constructed wetlands play an important role in water resources recycle. They can purify domestic wastewater for water recycling and reuse. After treating from constructed wetlands, the reclaimed water can be reused in washing toilets, watering gardens and irrigating farms. Constructed wetland is one of highly economic benefits for treating wastewater through imitating the processing mechanism of natural wetlands. In general, the treatment efficiency of constructed wetlands is determined by evapotranspiration, inflow, and water temperature. This study uses system dynamics modeling to develop models for different water resource components in a rural community. Furthermore, these models are integrated into a whole system. The model not only is utilized to simulate how water moves through different components, including residence houses, constructed wetlands and farms, but also evaluates the efficiency of water use. By analyzing the flow of water, the water resource simulation model can optimizes water resource distribution under different scenarios, and the result can provide suggestions for designing water resource system of a

  19. Understanding transport in model water desalination membranes

    Science.gov (United States)

    Chan, Edwin

    Polyamide based thin film composites represent the the state-of-the-art nanofiltration and reverse osmosis membranes used in water desalination. The performance of these membranes is enabled by the ultrathin (~100 nm) crosslinked polyamide film in facilitating the selective transport of water over salt ions. While these materials have been refined over the last several decades, understanding the relationships between polyamide structure and membrane performance remains a challenge because of the complex and heterogeneous nature of the polyamide film. In this contribution, we present our approach to addressing this challenge by studying the transport properties of model polyamide membranes synthesized via molecular layer-by-layer (mLbL) assembly. First, we demonstrate that mLbL can successfully construct polyamide membranes with well-defined nanoscale thickness and roughness using a variety of monomer formulations. Next, we present measurement tools for characterizing the network structure and transport of these model polyamide membranes. Specifically, we used X-ray and neutron scattering techniques to characterize their structure as well as a recently-developed indentation based poromechanics approach to extrapolate their water diffusion coefficient. Finally, we illustrate how these measurements can provide insight into the original problem by linking the key polyamide network properties, i.e. water-polyamide interaction parameter and characteristic network mesh size, to the membrane performance.

  20. Potential Release Site Sediment Concentrations Correlated to Storm Water Station Runoff through GIS Modeling

    Energy Technology Data Exchange (ETDEWEB)

    C.T. McLean

    2005-06-01

    This research examined the relationship between sediment sample data taken at Potential Release Sites (PRSs) and storm water samples taken at selected sites in and around Los Alamos National Laboratory (LANL). The PRSs had been evaluated for erosion potential and a matrix scoring system implemented. It was assumed that there would be a stronger relationship between the high erosion PRSs and the storm water samples. To establish the relationship, the research was broken into two areas. The first area was raster-based modeling, and the second area was data analysis utilizing the raster based modeling results and the sediment and storm water sample results. Two geodatabases were created utilizing raster modeling functions and the Arc Hydro program. The geodatabase created using only Arc Hydro functions contains very fine catchment drainage areas in association with the geometric network and can be used for future contaminant tracking. The second geodatabase contains sub-watersheds for all storm water stations used in the study along with a geometric network. The second area of the study focused on data analysis. The analytical sediment data table was joined to the PRSs spatial data in ArcMap. All PRSs and PRSs with high erosion potential were joined separately to create two datasets for each of 14 analytes. Only the PRSs above the background value were retained. The storm water station spatial data were joined to the table of analyte values that were either greater than the National Pollutant Discharge Elimination System (NPDES) Multi-Sector General Permit (MSGP) benchmark value, or the Department of Energy (DOE) Drinking Water Defined Contribution Guideline (DWDCG). Only the storm water stations were retained that had sample values greater than the NPDES MSGP benchmark value or the DOE DWDCG. Separate maps were created for each analyte showing the sub-watersheds, the PRSs over background, and the storm water stations greater than the NPDES MSGP benchmark value or the

  1. AWRA-G: A continental scale groundwater component linked to a land surface water balance model

    Science.gov (United States)

    Joehnk, Klaus; Crosbie, Russell; Peeters, Luk; Doble, Rebecca

    2013-04-01

    The Australian Water Resources Assessment (AWRA) system is a combination of models, data sources and analysis techniques that together will describe the water balance of Australia's landscapes, rivers and groundwater systems. It is a grid based water balance model that has lumped representation of the water balance of the soil, groundwater and surface water stores for each cell. The purpose of AWRA is to operationally provide up to date, credible, comprehensive, and accurate information about the history, present state and future trajectory of the water balance across Australia with sufficient spatial and temporal detail and enable water resources management for undertaking annual water resource assessments and national water accounts. AWRA is developed to link three major components: a landscape water balance model (AWRA-L), a river routing model (AWRA-R), and a groundwater component model (AWRA-G). These three component models combined are expected to be able to model the fluxes and stores of water throughout the landscape. The groundwater component (AWRA-G) addresses an improved representation of groundwater in the AWRA system to describe basic aquifer dynamics and groundwater-surface water processes. While most continental scale land surface models do not have the capacity to allow water to flow between cells and thus ignore this element of the water balance, AWRA-G does account for lateral flows. In general, AWRA-G provides estimates of groundwater fluxes that are not incorporated into either AWRA-L and its modifications to in-cell soil and groundwater processes, or AWRA-R. The processes integrated into AWRA-G thus are lateral groundwater flow between cells in regional and intermediate groundwater flow systems, groundwater discharge to the ocean, groundwater extraction and infiltration, river losses to groundwater, recharge from overbank flooding, and interactions between deep confined systems and surficial groundwater systems. Basis of AWRA-G is a good

  2. Modeling analysis of ground water recharge potential on alluvial fans using limited data.

    Science.gov (United States)

    Munévar, A; Mariño, M A

    1999-01-01

    A modeling approach is developed to evaluate the potential for artificial recharge on alluvial fans in the Salinas Valley, California, using limited data of soil texture, soil hydraulic properties, and interwell stratigraphy. Promising areas for surface recharge are identified and mapped on a broad-scale using soil surveys, geologic investigations, permeability tests, and seasonal ground water response to rainfall and runoff. Two-dimensional representations of the vadose zone at selected sites are then constructed from drillers'logs and soil material types are estimated. Next, hydraulic properties are assigned to each soil material type by comparing them to laboratory-tested cores of similar soils taken from one site. Finally, water flow through the vadose zone is modeled in two dimensions at seven sites using a transient, finite-difference, variably saturated flow model. Average infiltration rates range from 0.84 to 1.54 cm/hr and recharge efficiency, the percentage of infiltrated water that reaches the water table, varies from 51% to 79%. Infiltration rates and recharge efficiency are found to be relatively insensitive to recharge basin ponding depth due to the thickness of the vadose zones modeled (31 to 84 m). The impact of artificial recharge on the Salinas Valley ground water basin is investigated by simulating the regional ground water response to surface spreading and streamflow augmentation with a recently calibrated, finite-element, ground water-surface water model for the basin. It was determined that a combined approach of surface recharge and streamflow augmentation significantly reduces the state of ground water overdraft and, to a lesser extent, reduces the rate of sea water intrusion.

  3. Data model and relational database design for the New England Water-Use Data System (NEWUDS)

    Science.gov (United States)

    Tessler, Steven

    2001-01-01

    The New England Water-Use Data System (NEWUDS) is a database for the storage and retrieval of water-use data. NEWUDS can handle data covering many facets of water use, including (1) tracking various types of water-use activities (withdrawals, returns, transfers, distributions, consumptive-use, wastewater collection, and treatment); (2) the description, classification and location of places and organizations involved in water-use activities; (3) details about measured or estimated volumes of water associated with water-use activities; and (4) information about data sources and water resources associated with water use. In NEWUDS, each water transaction occurs unidirectionally between two site objects, and the sites and conveyances form a water network. The core entities in the NEWUDS model are site, conveyance, transaction/rate, location, and owner. Other important entities include water resources (used for withdrawals and returns), data sources, and aliases. Multiple water-exchange estimates can be stored for individual transactions based on different methods or data sources. Storage of user-defined details is accommodated for several of the main entities. Numerous tables containing classification terms facilitate detailed descriptions of data items and can be used for routine or custom data summarization. NEWUDS handles single-user and aggregate-user water-use data, can be used for large or small water-network projects, and is available as a stand-alone Microsoft? Access database structure. Users can customize and extend the database, link it to other databases, or implement the design in other relational database applications.

  4. Modeling regulated water utility investment incentives

    Science.gov (United States)

    Padula, S.; Harou, J. J.

    2014-12-01

    This work attempts to model the infrastructure investment choices of privatized water utilities subject to rate of return and price cap regulation. The goal is to understand how regulation influences water companies' investment decisions such as their desire to engage in transfers with neighbouring companies. We formulate a profit maximization capacity expansion model that finds the schedule of new supply, demand management and transfer schemes that maintain the annual supply-demand balance and maximize a companies' profit under the 2010-15 price control process in England. Regulatory incentives for costs savings are also represented in the model. These include: the CIS scheme for the capital expenditure (capex) and incentive allowance schemes for the operating expenditure (opex) . The profit-maximizing investment program (what to build, when and what size) is compared with the least cost program (social optimum). We apply this formulation to several water companies in South East England to model performance and sensitivity to water network particulars. Results show that if companies' are able to outperform the regulatory assumption on the cost of capital, a capital bias can be generated, due to the fact that the capital expenditure, contrarily to opex, can be remunerated through the companies' regulatory capital value (RCV). The occurrence of the 'capital bias' or its entity depends on the extent to which a company can finance its investments at a rate below the allowed cost of capital. The bias can be reduced by the regulatory penalties for underperformances on the capital expenditure (CIS scheme); Sensitivity analysis can be applied by varying the CIS penalty to see how and to which extent this impacts the capital bias effect. We show how regulatory changes could potentially be devised to partially remove the 'capital bias' effect. Solutions potentially include allowing for incentives on total expenditure rather than separately for capex and opex and allowing

  5. Influence of landscape heterogeneity on water availability to tropical forests in an Amazonian catchment and implications for modeling drought response

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yilin; Leung, Ruby L.; Duan, Zhuoran; Wigmosta, Mark S.; Maxwell, Reed M.; Chambers, Jeffrey Q.; Tomasella, Javier

    2017-08-18

    The Amazon basin experienced periodic droughts in the past, and climate models projected more intense and frequent droughts in the future. How tropical forests respond to drought may depend on water availability, which is modulated by landscape heterogeneity. Using the one-dimensional ACME Land Model (ALM) and the three-dimensional ParFlow variably saturated flow model, a series of numerical experiments were performed for the Asu catchment in central Amazon to elucidate processes that influence water available for plant use and provide insights for improving Earth system models. Results from ParFlow show that topography has a dominant influence on groundwater table and runoff through lateral flow. Without any representations of lateral processes, ALM simulates very different seasonal variations in groundwater table and runoff compared to ParFlow even if it is able to reproduce the long-term spatial average groundwater table of ParFlow through simple parameter calibration. In the ParFlow simulations, the groundwater table is evidently deeper and the soil saturation is lower in the plateau compared to the valley. However, even in the plateau during the dry season in the drought year of 2005, plant transpiration is not water stressed in the ParFlow simulations as the soil saturation is still sufficient to maintain a soil matric potential for the stomata to be fully open. This finding is insensitive to uncertainty in atmospheric forcing and soil parameters, but the empirical wilting formulation used in the models is an important factor that should be addressed using observations and modeling of coupled plant hydraulics-soil hydrology processes in future studies.

  6. General purpose steam table library :

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, John H.; Belcourt, Kenneth Noel; Nourgaliev, Robert

    2013-08-01

    Completion of the CASL L3 milestone THM.CFD.P7.04 provides a general purpose tabular interpolation library for material properties to support, in particular, standardized models for steam properties. The software consists of three parts, implementations of analytic steam models, a code to generate tables from those models, and an interpolation package to interface the tables to CFD codes such as Hydra-TH. Verification of the standard model is maintained through the entire train of routines. The performance of interpolation package exceeds that of freely available analytic implementation of the steam properties by over an order of magnitude.

  7. Advances in the Coupled Soil Water and Groundwater Models

    Institute of Scientific and Technical Information of China (English)

    杨玉峥; 王志敏

    2014-01-01

    Models simulating the reciprocal transformation between the soil water and groundwater are of great practical importance to the development and utilization of water resources and prevention and remedy of water pollution. In this paper, popular coupled models of soil water and groundwater will be analyzed. Besides, advantages and disadvantages of different models will be summarized as a reference for the numerical model of soil water and groundwater.

  8. League tables for orthodontists

    Science.gov (United States)

    Richmond, Stephen; Phillips, Ceri; Durning, Peter

    2008-01-01

    The aim of this study was to explore the complexities in constructing league tables purporting to measure orthodontic clinical outcomes. Eighteen orthodontists were invited to participate in a cost-effectiveness study. Each orthodontist was asked to provide information on 100 consecutively treated patients. The Index of Complexity, Outcome, and Need (ICON) was used to assess treatment need, complexity, and outcome prior to, and on completion of, orthodontic treatment. The 18 orthodontists were ranked based on achieving a successful orthodontic outcome (ICON score less than or equal to 30) and the uncertainty in both the success rates and rankings was also quantified using confidence intervals. Successful outcomes were achieved in 62 per cent of the sample (range 19–94 per cent); four of the 18 orthodontists failed to achieve more than a 50 per cent success rate. In developing league tables, it is imperative that factors such as case mix are identified and accounted for in producing rankings. Bayesian hierarchical modelling was used to achieve this and to quantify uncertainty in the rankings produced. When case mix was taken into account, the four with low success rates were clearly not as good as the top four performing orthodontists. League tables can be valuable for the individual orthodontist, groups of orthodontists, payment/insurance agencies, and the public to enable informed choice for orthodontic provision but must be correctly constructed so that users can have confidence in them. PMID:18687990

  9. FEWA: a Finite Element model of Water flow through Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.; Huff, D.D.

    1983-11-01

    This report documents the implementation and demonstration of a Finite Element model of Water flow through Aquifers (FEWA). The particular features of FEWA are its versatility and flexibility to deal with as many real-world problems as possible. Point as well as distributed sources/sinks are included to represent recharges/pumpings and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Source/sink strength over each element and node, hydraulic head at each Dirichlet boundary node, and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution method for the matrix equation approximating the partial differential equation of groundwater flow. FEWA also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. It is then demonstrated by two examples of how the model can be applied to heterogeneous and anisotropic aquifers with transient boundary conditions, time-dependent sources/sinks, and confining aquitards for a confined aquifer of variable thickness and for a free surface problem in an unconfined aquifer, respectively. 20 references, 25 figures, 8 tables.

  10. Analysis of spatial-temporal patterns of water table change as a tool for conjunctive water management in the Upper Central Plain of the Chao Phraya River Basin, Thailand

    Science.gov (United States)

    Vasconcelos, Vitor Vieira; Koontanakulvong, Sucharit; Suthidhummajit, Chokchai; Junior, Paulo Pereira Martins; Hadad, Renato Moreira

    2014-11-01

    A sustainable strategy for conjunctive water management must include information on the temporal and spatial availability of this natural resource. Because of water shortages in the dry seasons, farmers on the Upper Plain of the Chao Phraya River basin, Thailand, are increasingly using groundwater to meet their irrigation needs. To evaluate the possibilities of conjunctive water management in the area, the spatial-temporal changes in the water table of the Younger Terrace Aquifer were investigated. First, a regional geomorphological map based on field surveys, remote sensing and previous environmental studies was developed. Then, the well data were analyzed in relation to rainfall, streamflow, yield and pumpage, and the data were interpolated using geostatistical techniques. The results were analyzed via integrated zoning based on color theory as applied to multivariate visualization. The analysis results indicate areas that would be more suitable for groundwater extraction in a conjunctive management framework with regard to the natural hydrogeological processes and the effects of human interaction. The kriging results were compared with the geomorphological map, and the geomorphological areas exhibit distinct hydrogeological patterns. The western fans exhibit the best potential for the expansion of conjunctive use, whereas the borders of the northern fans exhibit the lowest potential.

  11. Analysis of spatial-temporal patterns of water table change as a tool for conjunctive water management in the Upper Central Plain of the Chao Phraya River Basin, Thailand

    Science.gov (United States)

    Vasconcelos, Vitor Vieira; Koontanakulvong, Sucharit; Suthidhummajit, Chokchai; Junior, Paulo Pereira Martins; Hadad, Renato Moreira

    2017-03-01

    A sustainable strategy for conjunctive water management must include information on the temporal and spatial availability of this natural resource. Because of water shortages in the dry seasons, farmers on the Upper Plain of the Chao Phraya River basin, Thailand, are increasingly using groundwater to meet their irrigation needs. To evaluate the possibilities of conjunctive water management in the area, the spatial-temporal changes in the water table of the Younger Terrace Aquifer were investigated. First, a regional geomorphological map based on field surveys, remote sensing and previous environmental studies was developed. Then, the well data were analyzed in relation to rainfall, streamflow, yield and pumpage, and the data were interpolated using geostatistical techniques. The results were analyzed via integrated zoning based on color theory as applied to multivariate visualization. The analysis results indicate areas that would be more suitable for groundwater extraction in a conjunctive management framework with regard to the natural hydrogeological processes and the effects of human interaction. The kriging results were compared with the geomorphological map, and the geomorphological areas exhibit distinct hydrogeological patterns. The western fans exhibit the best potential for the expansion of conjunctive use, whereas the borders of the northern fans exhibit the lowest potential.

  12. 21 CFR 168.180 - Table sirup.

    Science.gov (United States)

    2010-04-01

    ... added for nutritional purposes and artificial sweeteners are not considered to be suitable ingredients... CONSUMPTION SWEETENERS AND TABLE SIRUPS Requirements for Specific Standardized Sweeteners and Table Sirups... percent soluble sweetener solids by weight and is prepared with or without added water. It may contain...

  13. 40 CFR Table 7 to Subpart Bbbb of... - Model Rule-Requirements for Continuous Emission Monitoring Systems (CEMS)

    Science.gov (United States)

    2010-07-01

    ... Emission Monitoring Systems (CEMS) 7 Table 7 to Subpart BBBB of Part 60 Protection of Environment...—Requirements for Continuous Emission Monitoring Systems (CEMS) For the following pollutants Use the following span values for CEMS Use the following performance specifications in appendix B of this part for...

  14. Crop water parameters of irrigated wine and table grapes to support water productivity analysis in the Sao Francisco river basin, Brazil

    NARCIS (Netherlands)

    Castro Teixeira, de A.H.; Bastiaanssen, W.G.M.; Bassoi, L.H.

    2007-01-01

    Energy and water balance parameters were measured in two commercial vineyards in the semiarid region of the São Francisco river basin, Brazil. Actual evapotranspiration (ET) was acquired with the Bowen ratio surface energy balance method. The ratio of the latent heat flux to the available energy, or

  15. Monthly Water Balance Model Hydrology Futures

    Science.gov (United States)

    Bock, Andy; Hay, Lauren E.; Markstrom, Steven; Atkinson, R. Dwight

    2016-01-01

    A monthly water balance model (MWBM) was driven with precipitation and temperature using a station-based dataset for current conditions (1950 to 2010) and selected statistically-downscaled general circulation models (GCMs) for current and future conditions (1950 to 2099) across the conterminous United States (CONUS) using hydrologic response units from the Geospatial Fabric for National Hydrologic Modeling (http://dx.doi.org/doi:10.5066/F7542KMD). Six MWBM output variables (actual evapotranspiration (AET), potential evapotranspiration (PET), runoff (RO), streamflow (STRM), soil moisture storage (SOIL), and snow water equivalent (SWE)) and the two MWBM input variables (atmospheric temperature (TAVE) and precipitation (PPT)) were summarized for hydrologic response units and aggregated at points of interest on a stream network. Results were then organized into the Monthly Water Balance Hydrology Futures database, an open-access database using netCDF format (http://cida-eros-mows1.er.usgs.gov/thredds/dodsC/nwb_pub/).  Methods used to calibrate and parameterize the MWBM are detailed in the Hydrology and Earth System Sciences (HESS)  paper "Parameter regionalization of a monthly water balance model for the conterminous United States" by Bock and others (2016).  See the discussion paper link in the "Related External Resources" section for access.  Supplemental data files related to the plots and data analysis in Bock and others (2016) can be found in the HESS-2015-325.zip folder in the "Attached Files" section.  Detailed information on the files and data can be found in the ReadMe.txt contained within the zipped folder. Recommended citation of discussion paper:Bock, A.R., Hay, L.E., McCabe, G.J., Markstrom, S.L., and Atkinson, R.D., 2016, Parameter regionalization of a monthly water balance model for the conterminous United States: Hydrology and Earth System Sciences, v. 20, 2861-2876, doi:10.5194/hess-20-2861-2016, 2016

  16. Virtual Prototype Modeling and Simulation Analysis of Hydraulic Shaking Table%液压振动台虚拟样机建模及仿真分析

    Institute of Scientific and Technical Information of China (English)

    崔伟清; 范顺成; 李艳艳; 王胜凯

    2012-01-01

    The three-dimensional solid model of hydraulic shaking table was built by using UG software. The solid model built was imported into ADAMS software via the data interface to build virtual prototype of the hydraulic shaking table. Then Matlab was chosen for establishing control system. The control system and virtual prototype perform co-simulation was realized through data interchange technology. The frequency response characteristics of the hydraulic shaking table were analyzed through simulation.%利用UG软件建立液压振动台三维实体模型,将建立的实体模型通过数据接口导入ADAMS软件,建立起液压振动台虚拟样机.利用Matlab软件建立控制系统,与ADAMS建立的虚拟样机通过数据交换技术进行联合仿真,对振动台系统的频响特性进行分析.

  17. Geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples, and its possible relationship with the prevalence of enamel fluorosis in children in four municipalities of the department of Huila (Colombia).

    Science.gov (United States)

    Martignon, Stefania; Opazo-Gutiérrez, Mario Omar; Velásquez-Riaño, Möritz; Orjuela-Osorio, Iván Rodrigo; Avila, Viviana; Martinez-Mier, Esperanza Angeles; González-Carrera, María Clara; Ruiz-Carrizosa, Jaime Alberto; Silva-Hermida, Blanca Cecilia

    2017-06-01

    Fluoride is an element that affects teeth and bone formation in animals and humans. Though the use of systemic fluoride is an evidence-based caries preventive measure, excessive ingestion can impair tooth development, mainly the mineralization of tooth enamel, leading to a condition known as enamel fluorosis. In this study, we investigated the geochemical characterization of fluoride in water, table salt, active sediment, rock and soil samples in four endemic enamel fluorosis sentinel municipalities of the department of Huila, Colombia (Pitalito, Altamira, El Agrado and Rivera), and its possible relationship with the prevalence of enamel fluorosis in children. The concentration of fluoride in drinking water, table salt, active sediment, rock, and soil was evaluated by means of an ion selective electrode and the geochemical analyses were performed using X-ray fluorescence. Geochemical analysis revealed fluoride concentrations under 15 mg/kg in active sediment, rock and soil samples, not indicative of a significant delivery to the watersheds studied. The concentration of fluoride in table salt was found to be under the inferior limit (less than 180 μg/g) established by the Colombian regulations. Likewise, exposure doses for fluoride water intake did not exceed the recommended total dose for all ages from 6 months. Although the evidence does not point out at rocks, soils, fluoride-bearing minerals, fluoridated salt and water, the hypothesis of these elements as responsible of the current prevalence of enamel fluorosis cannot be discarded since, aqueducts might have undergone significant changes overtime.

  18. Adaptive Control and Synchronization of the Shallow Water Model

    Directory of Open Access Journals (Sweden)

    P. Sangapate

    2012-01-01

    Full Text Available The shallow water model is one of the important models in dynamical systems. This paper investigates the adaptive chaos control and synchronization of the shallow water model. First, adaptive control laws are designed to stabilize the shallow water model. Then adaptive control laws are derived to chaos synchronization of the shallow water model. The sufficient conditions for the adaptive control and synchronization have been analyzed theoretically, and the results are proved using a Barbalat's Lemma.

  19. Impacts of model initialization on an integrated surface water - groundwater model

    KAUST Repository

    Ajami, Hoori

    2015-04-01

    Integrated hydrologic models characterize catchment responses by coupling the subsurface flow with land surface processes. One of the major areas of uncertainty in such models is the specification of the initial condition and its influence on subsequent simulations. A key challenge in model initialization is that it requires spatially distributed information on model states, groundwater levels and soil moisture, even when such data are not routinely available. Here, the impact of uncertainty in initial condition was explored across a 208 km2 catchment in Denmark using the ParFlow.CLM model. The initialization impact was assessed under two meteorological conditions (wet vs dry) using five depth to water table and soil moisture distributions obtained from various equilibrium states (thermal, root zone, discharge, saturated and unsaturated zone equilibrium) during the model spin-up. Each of these equilibrium states correspond to varying computation times to achieve stability in a particular aspect of the system state. Results identified particular sensitivity in modelled recharge and stream flow to the different initializations, but reduced sensitivity in modelled energy fluxes. Analysis also suggests that to simulate a year that is wetter than the spin-up period, an initialization based on discharge equilibrium is adequate to capture the direction and magnitude of surface water–groundwater exchanges. For a drier or hydrologically similar year to the spin-up period, an initialization based on groundwater equilibrium is required. Variability of monthly subsurface storage changes and discharge bias at the scale of a hydrological event show that the initialization impacts do not diminish as the simulations progress, highlighting the importance of robust and accurate initialization in capturing surface water–groundwater dynamics.

  20. Modelling of water permeability in cementitious materials

    DEFF Research Database (Denmark)

    Guang, Ye; Lura, Pietro; van Breugel, K.

    2006-01-01

    This paper presents a network model to predict the permeability of cement paste from a numerical simulation of its microstructure. Based on a linked list pore network structure, the effective hydraulic conductivity is estimated and the fluid flow is calculated according to the Hagen-Poiseuille law....... The pressure gradient at all nodes is calculated with the Gauss elimination method and the absolute permeability of the pore network is calculated directly from Darcy's law. Finally, the permeability model is validated by comparison with direct water permeability measurements. According to this model......, the predicted permeability of hydrating cement pastes is extremely sensitive to the particle size distribution of the cement and especially to the minimum size of the cement particles. Both in simulations and experiments, the permeability of cement pastes is mainly determined by the critical diameter...

  1. Lattice Boltzmann modeling of water entry problems

    Science.gov (United States)

    Zarghami, A.; Falcucci, G.; Jannelli, E.; Succi, S.; Porfiri, M.; Ubertini, S.

    2014-12-01

    This paper deals with the simulation of water entry problems using the lattice Boltzmann method (LBM). The dynamics of the free surface is treated through the mass and momentum fluxes across the interface cells. A bounce-back boundary condition is utilized to model the contact between the fluid and the moving object. The method is implemented for the analysis of a two-dimensional flow physics produced by a symmetric wedge entering vertically a weakly-compressible fluid at a constant velocity. The method is used to predict the wetted length, the height of water pile-up, the pressure distribution and the overall force on the wedge. The accuracy of the numerical results is demonstrated through comparisons with data reported in the literature.

  2. Ground-water models: Validate or invalidate

    Science.gov (United States)

    Bredehoeft, J.D.; Konikow, L.F.

    1993-01-01

    The word validation has a clear meaning to both the scientific community and the general public. Within the scientific community the validation of scientific theory has been the subject of philosophical debate. The philosopher of science, Karl Popper, argued that scientific theory cannot be validated, only invalidated. Popper’s view is not the only opinion in this debate; however, many scientists today agree with Popper (including the authors). To the general public, proclaiming that a ground-water model is validated carries with it an aura of correctness that we do not believe many of us who model would claim. We can place all the caveats we wish, but the public has its own understanding of what the word implies. Using the word valid with respect to models misleads the public; verification carries with it similar connotations as far as the public is concerned. Our point is this: using the terms validation and verification are misleading, at best. These terms should be abandoned by the ground-water community.

  3. Modeling terahertz heating effects on water

    DEFF Research Database (Denmark)

    Kristensen, Torben T.L.; Withayachumnankul, Withawat; Jepsen, Peter Uhd;

    2010-01-01

    We apply Kirchhoff’s heat equation to model the influence of a CW terahertz beam on a sample of water, which is assumed to be static. We develop a generalized model, which easily can be applied to other liquids and solids by changing the material constants. If the terahertz light source is focused...... down to a spot with a diameter of 0.5 mm, we find that the steadystate temperature increase per milliwatt of transmitted power is 1.8◦C/mW. A quantum cascade laser can produce a CW beam in the order of several milliwatts and this motivates the need to estimate the effect of beam power on the sample...... temperature. For THz time domain systems, we indicate how to use our model as a worst-case approximation based on the beam average power. It turns out that THz pulses created from photoconductive antennas give a negligible increase in temperature. As biotissue contains a high water content, this leads...

  4. A Conceptual Model for Water Sensitive City in Surabaya

    Science.gov (United States)

    Pamungkas, A.; Tucunan, K. P.; Navastara, A.; Idajati, H.; Pratomoatmojo, N. A.

    2017-08-01

    Frequent inundated areas, low quality of water supply, highly dependent water sources from external are some key problems in Surabaya water balance. Many aspects of urban development have stimulated those problems. To uncover the complexity of water balance in Surabaya, a conceptual model for water sensitive city is constructed to find the optimum solution. A system dynamic modeling is utilized to assist and enrich the idea of conceptual model. A secondary analysis to a wide range data directs the process in making a conceptual model. FGD involving many experts from multidiscipline are also used to finalize the conceptual model. Based on those methods, the model has four main sub models that are; flooding, land use change, water demand and water supply. The model consists of 35 key variables illustrating challenges in Surabaya urban water.

  5. Integrated modeling of ozonation for optimization of drinking water treatment

    NARCIS (Netherlands)

    van der Helm, A.W.C.

    2007-01-01

    Drinking water treatment plants automation becomes more sophisticated, more on-line monitoring systems become available and integration of modeling environments with control systems becomes easier. This gives possibilities for model-based optimization. In operation of drinking water treatment

  6. Table-top water window transmission x-ray microscopy: Review of the key issues, and conceptual design of an instrument for biology

    Science.gov (United States)

    Adam, Jean-François; Moy, Jean-Pierre; Susini, Jean

    2005-09-01

    As it has been beautifully demonstrated in synchrotron facilities, water window transmission x-ray microscopy (WW-TXM) has a great potential for high resolution three dimensional (3D) tomographic imaging of frozen cells, without the cumbersome staining and slicing preparation needed by electron microscopy. However, the existing instruments do not exactly meet the expectations of cell biologists in terms of performance and accessibility: 3D images of entire cells grown on a flat substrate with details in the 50-80nm range are necessary for structural cell studies. Functional imaging is also a key issue. Specific molecular probes are widely used to achieve molecular imaging in optical and electron microscopy. The same demand applies to x-ray microscopy. Immediate availability of the observation technique within the biology laboratory is as important as its performance. Therefore, WW-TXM will develop on a wider scale only when table-top instruments become available. We present a detailed analysis of such a microscope. The source is clearly the key element. Laser created plasmas of carbon or nitrogen are a proven but expensive solution. Cerenkov emission in vanadium has been demonstrated as a potential monochromatic source, but we emphasize severe obstacles: huge thermal load and radiation protection. We show that oxygenKα line excitation by an electron beam is a realistic alternative. Being a purely monochromatic source, it would allow the use of a high efficiency mirror condenser, while laser plasmas imply spectral selection with the associated losses. We then describe the main elements of an affordable laboratory microscope, supported by numerical simulations and preliminary experimental work. We also show that functionalized quantum dots, currently used in fluorescence microscopy, are equally detectable with soft x-rays and would allow a dual modality observation. Finally, the expected performance of this prototype is discussed and confronted by the requirements

  7. Variable table applied in parameteric product model design using Solid Edge%变量表在Solid Edge参数化设计中的应用

    Institute of Scientific and Technical Information of China (English)

    王劲; 肖冰; 由艳平

    2012-01-01

    设置变量表是利用Solid Edge进行三维产品模型参数化设计的常用方法.介绍了变量表中变量的类型和属性的设置方法,说明了设置变量变化范围所使用的符号以及设置变量间简单函数关系的算术运算符和数学函数,给出了VBA过程的语法格式,通过变量表加载VBA过程可以设置变量间比较复杂的关系,说明了VBA编程的应用方法.%The common method in three-dimensional product model parameteric design using Solid Edge is setting the variable table . This article introduces the type of variables in the variable table and the setting method of variable attributes. The symbols used to set the variable range and arithmetic operators and math functions for a simple functional relationship between variables are illustrated . The grammar format of VBA is given. The process of the variable table loading VBA can set more complex relationship between variables. The application of VBA programming method is introduced.

  8. Evaluating a microbial water quality prediction model for beach management under the revised EU Bathing Water Directive.

    Science.gov (United States)

    Bedri, Zeinab; Corkery, Aisling; O'Sullivan, John J; Deering, Louise A; Demeter, Katalin; Meijer, Wim G; O'Hare, Gregory; Masterson, Bartholomew

    2016-02-01

    The revised Bathing Water Directive (2006/7/EC) requires EU member states to minimise the risk to public health from faecal pollution at bathing waters through improved monitoring and management approaches. While increasingly sophisticated measurement methods (such as microbial source tracking) assist in the management of bathing water resources, the use of deterministic predictive models for this purpose, while having the potential to provide decision making support, remains less common. This study explores an integrated, deterministic catchment-coastal hydro-environmental model as a decision-making tool for beach management which, based on advance predictions of bathing water quality, can inform beach managers on appropriate management actions (to prohibit bathing or advise the public not to bathe) in the event of a poor water quality forecast. The model provides a 'moving window' five-day forecast of Escherichia coli levels at a bathing water compliance point off the Irish coast and the accuracy of bathing water management decisions were investigated for model predictions under two scenarios over the period from the 11th August to the 5th September, 2012. Decisions for Scenario 1 were based on model predictions where rainfall forecasts from a meteorological source (www.yr.no) were used to drive the rainfall-runoff processes in the catchment component of the model, and for Scenario 2, were based on predictions that were improved by incorporating real-time rainfall data from a sensor network within the catchment into the forecasted meteorological input data. The accuracy of the model in the decision-making process was assessed using the contingency table and its metrics. The predictive model gave reasonable outputs to support appropriate decision making for public health protection. Scenario 1 provided real-time predictions that, on 77% of instances during the study period where both predicted and E. coli concentrations were available, would correctly inform a

  9. Model for radionuclide transport in running waters

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, Karin; Elert, Mark [Kemakta Konsult AB, Stockholm (Sweden)

    2005-11-15

    Two sites in Sweden are currently under investigation by SKB for their suitability as places for deep repository of radioactive waste, the Forsmark and Simpevarp/Laxemar area. As a part of the safety assessment, SKB has formulated a biosphere model with different sub-models for different parts of the ecosystem in order to be able to predict the dose to humans following a possible radionuclide discharge from a future deep repository. In this report, a new model concept describing radionuclide transport in streams is presented. The main difference from the previous model for running water used by SKB, where only dilution of the inflow of radionuclides was considered, is that the new model includes parameterizations also of the exchange processes present along the stream. This is done in order to be able to investigate the effect of the retention on the transport and to be able to estimate the resulting concentrations in the different parts of the system. The concentrations determined with this new model could later be used for order of magnitude predictions of the dose to humans. The presented model concept is divided in two parts, one hydraulic and one radionuclide transport model. The hydraulic model is used to determine the flow conditions in the stream channel and is based on the assumption of uniform flow and quasi-stationary conditions. The results from the hydraulic model are used in the radionuclide transport model where the concentration is determined in the different parts of the stream ecosystem. The exchange processes considered are exchange with the sediments due to diffusion, advective transport and sedimentation/resuspension and uptake of radionuclides in biota. Transport of both dissolved radionuclides and sorbed onto particulates is considered. Sorption kinetics in the stream water phase is implemented as the time scale of the residence time in the stream water probably is short in comparison to the time scale of the kinetic sorption. In the sediment

  10. Carbon dioxide flux and net primary production of a boreal treed bog: Responses to warming and water-table-lowering simulations of climate change

    Science.gov (United States)

    Munir, T. M.; Perkins, M.; Kaing, E.; Strack, M.

    2015-02-01

    Midlatitude treed bogs represent significant carbon (C) stocks and are highly sensitive to global climate change. In a dry continental treed bog, we compared three sites: control, recent (1-3 years; experimental) and older drained (10-13 years), with water levels at 38, 74 and 120 cm below the surface, respectively. At each site we measured carbon dioxide (CO2) fluxes and estimated tree root respiration (Rr; across hummock-hollow microtopography of the forest floor) and net primary production (NPP) of trees during the growing seasons (May to October) of 2011-2013. The CO2-C balance was calculated by adding the net CO2 exchange of the forest floor (NEff-Rr) to the NPP of the trees. From cooler and wetter 2011 to the driest and the warmest 2013, the control site was a CO2-C sink of 92, 70 and 76 g m-2, the experimental site was a CO2-C source of 14, 57 and 135 g m-2, and the drained site was a progressively smaller source of 26, 23 and 13 g CO2-C m-2. The short-term drainage at the experimental site resulted in small changes in vegetation coverage and large net CO2 emissions at the microforms. In contrast, the longer-term drainage and deeper water level at the drained site resulted in the replacement of mosses with vascular plants (shrubs) on the hummocks and lichen in the hollows leading to the highest CO2 uptake at the drained hummocks and significant losses in the hollows. The tree NPP (including above- and below-ground growth and litter fall) in 2011 and 2012 was significantly higher at the drained site (92 and 83 g C m-2) than at the experimental (58 and 55 g C m-2) and control (52 and 46 g C m-2) sites. We also quantified the impact of climatic warming at all water table treatments by equipping additional plots with open-top chambers (OTCs) that caused a passive warming on average of ~ 1 °C and differential air warming of ~ 6 °C at midday full sun over the study years. Warming significantly enhanced shrub growth and the CO2 sink function of the drained

  11. Evaluating Water Conservation and Reuse Policies Using a Dynamic Water Balance Model

    Science.gov (United States)

    Qaiser, Kamal; Ahmad, Sajjad; Johnson, Walter; Batista, Jacimaria R.

    2013-02-01

    A dynamic water balance model is created to examine the effects of different water conservation policies and recycled water use on water demand and supply in a region faced with water shortages and significant population growth, the Las Vegas Valley (LVV). The model, developed using system dynamics approach, includes an unusual component of the water system, return flow credits, where credits are accrued for returning treated wastewater to the water supply source. In LVV, Lake Mead serves as, both the drinking water source and the receiving body for treated wastewater. LVV has a consumptive use allocation from Lake Mead but return flow credits allow the water agency to pull out additional water equal to the amount returned as treated wastewater. This backdrop results in a scenario in which conservation may cause a decline in the available water supply. Current water use in LVV is 945 lpcd (250 gpcd), which the water agency aims to reduce to 752 lpcd (199 gpcd) by 2035, mainly through water conservation. Different conservation policies focused on indoor and outdoor water use, along with different population growth scenarios, are modeled for their effects on the water demand and supply. Major contribution of this study is in highlighting the importance of outdoor water conservation and the effectiveness of reducing population growth rate in addressing the future water shortages. The water agency target to decrease consumption, if met completely through outdoor conservation, coupled with lower population growth rate, can potentially satisfy the Valley's water demands through 2035.

  12. NNDSS - Table II. Vibriosis

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table II. Vibriosis - 2017. In this Table, provisional cases of selected notifiable diseases (≥1,000 cases reported during the preceding year), and...

  13. NNDSS - Table IV. Tuberculosis

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table IV. Tuberculosis - 2014.This Table includes total number of cases reported in the United States, by region and by states, in accordance with the...

  14. NNDSS - Table IV. Tuberculosis

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table IV. Tuberculosis - 2016.This Table includes total number of cases reported in the United States, by region and by states, in accordance with the...

  15. NNDSS - Table IV. Tuberculosis

    Data.gov (United States)

    U.S. Department of Health & Human Services — NNDSS - Table IV. Tuberculosis - 2015.This Table includes total number of cases reported in the United States, by region and by states, in accordance with the...

  16. Pension Insurance Data Tables

    Data.gov (United States)

    Pension Benefit Guaranty Corporation — Find out about retirement trends in PBGC's data tables. The tables include statistics on the people and pensions that PBGC protects, including how many Americans are...

  17. Tabled Execution in Scheme

    Energy Technology Data Exchange (ETDEWEB)

    Willcock, J J; Lumsdaine, A; Quinlan, D J

    2008-08-19

    Tabled execution is a generalization of memorization developed by the logic programming community. It not only saves results from tabled predicates, but also stores the set of currently active calls to them; tabled execution can thus provide meaningful semantics for programs that seemingly contain infinite recursions with the same arguments. In logic programming, tabled execution is used for many purposes, both for improving the efficiency of programs, and making tasks simpler and more direct to express than with normal logic programs. However, tabled execution is only infrequently applied in mainstream functional languages such as Scheme. We demonstrate an elegant implementation of tabled execution in Scheme, using a mix of continuation-passing style and mutable data. We also show the use of tabled execution in Scheme for a problem in formal language and automata theory, demonstrating that tabled execution can be a valuable tool for Scheme users.

  18. 矿井带压开采疏水降压可行性模拟分析%Simulation Analysis on Feasibility of Water Pumping and Water Table Dropping for Pressurized Water Mining in Underground Mine

    Institute of Scientific and Technical Information of China (English)

    郭国强

    2013-01-01

    Based on the seams in North China Taiyuan Formation threatened by high pressurized water in the aquifer of Ordovician limestone,in order to improve the effective recovery rate of the coal resources,to avoid the waste of the coal resources and to reduce the danger of the pressurized mining,with the analysis on the hydrogeological conditions of the Ordovician limestone aquifer,an evaluation on the danger of the pressurized mining was conducted.Visual MODFLOW software was applied to establish a mine hydrogeological model.A safety water pumping and water pressure was set as 1 MPa and the water pumping quantity from the aquifer in Ordovician limestone was calculated.A feasibility analysis on the water pumping and pressure dropping was conducted on the water pumping quantity size,mine water drainage capacity,hydrogeological conditions,comprehensive utilization of the coal resources and others.The results showed that when the water pumping quantity was 8 676 m3/d,after 9 days water drainage,the water pressure of the Ordovician limestone would be stable,would be reduced to 1 MPa and would reach the designed safety water level.Thus the water pumping and the pressure dropping would be feasible and the pressurized mining could be safely conducted.%基于华北太原组煤层受到奥陶系灰岩含水层高承压水威胁,为提高煤炭资源采出率,减少煤炭资源损失以及降低矿井带压开采的危险性.通过分析奥灰含水层的水文地质条件,进行了带压开采危险性评价,利用Visual MODFLOW软件建立矿井水文地质模型,设定安全疏降水压为1 MPa,计算了矿井奥灰含水层疏降水量.从疏降水量大小、矿井排水能力、水文地质条件、水资源综合利用等方面进行了疏水降压可行性分析.结果表明,当疏降水量为8 676 m3/d时,经过9d排水,奥灰水压可稳定并降至1 MPa,达到设计的安全水位,疏水降压是可行的,矿井带压开采可以安全进行.

  19. Drinking Water Temperature Modelling in Domestic Systems

    NARCIS (Netherlands)

    Moerman, A.; Blokker, M.; Vreeburg, J.; Van der Hoek, J.P.

    2014-01-01

    Domestic water supply systems are the final stage of the transport process to deliver potable water to the customers’ tap. Under the influence of temperature, residence time and pipe materials the drinking water quality can change while the water passes the domestic drinking water system. According

  20. Modelling global fresh surface water temperature

    NARCIS (Netherlands)

    Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.

    2011-01-01

    Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment

  1. Modelling global fresh surface water temperature

    NARCIS (Netherlands)

    Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.

    2011-01-01

    Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment concentrati

  2. Periodic Table of Students.

    Science.gov (United States)

    Johnson, Mike

    1998-01-01

    Presents an exercise in which an eighth-grade science teacher decorated the classroom with a periodic table of students. Student photographs were arranged according to similarities into vertical columns. Students were each assigned an atomic number according to their placement in the table. The table is then used to teach students about…

  3. Periodic Table of Students.

    Science.gov (United States)

    Johnson, Mike

    1998-01-01

    Presents an exercise in which an eighth-grade science teacher decorated the classroom with a periodic table of students. Student photographs were arranged according to similarities into vertical columns. Students were each assigned an atomic number according to their placement in the table. The table is then used to teach students about…

  4. Table Tennis Club

    CERN Multimedia

    Table Tennis Club

    2013-01-01

    Apparently table tennis plays an important role in physics, not so much because physicists are interested in the theory of table tennis ball scattering, but probably because it provides useful breaks from their deep intellectual occupation. It seems that many of the greatest physicists took table tennis very seriously. For instance, Heisenberg could not even bear to lose a game of table tennis, Otto Frisch played a lot of table tennis, and had a table set up in his library, and Niels Bohr apparently beat everybody at table tennis. Therefore, as the CERN Table Tennis Club advertises on a poster for the next CERN Table Tennis Tournament: “if you want to be a great physicist, perhaps you should play table tennis”. Outdoor table at restaurant n° 1 For this reason, and also as part of the campaign launched by the CERN medical service “Move! & Eat better”, to encourage everyone at CERN to take regular exercise, the CERN Table Tennis Club, with the supp...

  5. Modelling water and {sup 36}Cl cycling in a Belgian pine forest - Model for {sup 36}Cl cycling in a Belgian pine forest

    Energy Technology Data Exchange (ETDEWEB)

    Vives i Batlle, Jordi; Vandenhove, Hildegarde; Gielen, Sienke [Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol (Belgium)

    2014-07-01

    A simplified, 1-D soil-groundwater-vegetation model to represent the cycling of water and of {sup 36}Cl in a Belgian Scots pine forest is presented and discussed. The model contains a soil column with layers of different (but uniform) field capacity and soil porosity, which are penetrated by tree roots. Flow through porous media is assumed to circulate according to Darcy and Philips laws, using empirical soil hydraulic properties without recourse to Richards' equation. The vegetation is represented by means of a compartment model including simplified representation of sap flow, translocation and litterfall in relation to different parts of the tree. The water table height is variable according to the balance between precipitation, capillary rise, solar radiation, plant uptake and evapotranspiration. The influence of local fluvial sources of water can also be evaluated in a simplified way as a losing/gaining stream input to the soil column. Time dependent data on temperature, solar irradiation, rainfall, crop coefficient and leaf area index (LAI) are used as input to the model in order to calculate evapotranspiration and a simplified approach to foliar interception. The chlorine flux follows the water flux in both soil and the trees, using retardation in soil and experimentally measured translocation factors within the plant. The chlorine flux is optimised and validated with recourse to a previous {sup 36}Cl compartment model. Although considered to be a relatively simple model, initial results suggest a reasonable consistency between previously published water balance and field measurements in a Scots pine stand from the vicinity of Mol, Belgium. The mean soil water content is predicted to be around 25%, the plant water is stored in the order roots > plant above roots > leaf surfaces, water table height below ground fluctuates between 2.1 and 2.6 m compared with a measured water table height of 1.8 - 20 m and pine transpiration is less than 1.2 mm/d compared

  6. Phase Equilibria of Water/CO2 and Water/n-Alkane Mixtures from Polarizable Models.

    Science.gov (United States)

    Jiang, Hao; Economou, Ioannis G; Panagiotopoulos, Athanassios Z

    2017-02-16

    Phase equilibria of water/CO2 and water/n-alkane mixtures over a range of temperatures and pressures were obtained from Monte Carlo simulations in the Gibbs ensemble. Three sets of Drude-type polarizable models for water, namely the BK3, GCP, and HBP models, were combined with a polarizable Gaussian charge CO2 (PGC) model to represent the water/CO2 mixture. The HBP water model describes hydrogen bonds between water and CO2 explicitly. All models underestimate CO2 solubility in water if standard combining rules are used for the dispersion interactions between water and CO2. With the dispersion parameters optimized to phase compositions, the BK3 and GCP models were able to represent the CO2 solubility in water, however, the water composition in CO2-rich phase is systematically underestimated. Accurate representation of compositions for both water- and CO2-rich phases cannot be achieved even after optimizing the cross interaction parameters. By contrast, accurate compositions for both water- and CO2-rich phases were obtained with hydrogen bonding parameters determined from the second virial coefficient for water/CO2. Phase equilibria of water/n-alkane mixtures were also studied using the HBP water and an exponenial-6 united-atom n-alkanes model. The dispersion interactions between water and n-alkanes were optimized to Henry's constants of methane and ethane in water. The HBP water and united-atom n-alkane models underestimate water content in the n-alkane-rich phase; this underestimation is likely due to the neglect of electrostatic and induction energies in the united-atom model.

  7. A marginal revenue equilibrium model for spatial water allocation

    Institute of Scientific and Technical Information of China (English)

    王劲峰; 刘昌明; 王智勇; 于静洁

    2002-01-01

    The outside water is transported into the water-shorted area. It is allocated among many sub-areas that composed the water-shorted area, in order to maximize the total benefit from the input water for the areas. This paper presents a model for spatial water allocation based on the marginal revenue of water utilization, taking the six southern districts of Hebei Province as an example.

  8. Modeling soil water content for vegetation modeling improvement

    Science.gov (United States)

    Cianfrani, Carmen; Buri, Aline; Zingg, Barbara; Vittoz, Pascal; Verrecchia, Eric; Guisan, Antoine

    2016-04-01

    Soil water content (SWC) is known to be important for plants as it affects the physiological processes regulating plant growth. Therefore, SWC controls plant distribution over the Earth surface, ranging from deserts and grassland to rain forests. Unfortunately, only a few data on SWC are available as its measurement is very time consuming and costly and needs specific laboratory tools. The scarcity of SWC measurements in geographic space makes it difficult to model and spatially project SWC over larger areas. In particular, it prevents its inclusion in plant species distribution model (SDMs) as predictor. The aims of this study were, first, to test a new methodology allowing problems of the scarcity of SWC measurements to be overpassed and second, to model and spatially project SWC in order to improve plant SDMs with the inclusion of SWC parameter. The study was developed in four steps. First, SWC was modeled by measuring it at 10 different pressures (expressed in pF and ranging from pF=0 to pF=4.2). The different pF represent different degrees of soil water availability for plants. An ensemble of bivariate models was built to overpass the problem of having only a few SWC measurements (n = 24) but several predictors to include in the model. Soil texture (clay, silt, sand), organic matter (OM), topographic variables (elevation, aspect, convexity), climatic variables (precipitation) and hydrological variables (river distance, NDWI) were used as predictors. Weighted ensemble models were built using only bivariate models with adjusted-R2 > 0.5 for each SWC at different pF. The second step consisted in running plant SDMs including modeled SWC jointly with the conventional topo-climatic variable used for plant SDMs. Third, SDMs were only run using the conventional topo-climatic variables. Finally, comparing the models obtained in the second and third steps allowed assessing the additional predictive power of SWC in plant SDMs. SWC ensemble models remained very good, with

  9. Dynamic FE simulation of four-story steel frame modeled by solid elements and its validation using results of full-scale shake-table test

    OpenAIRE

    Miyamura, Tomoshi; Yamashita, Takuzo; AKIBA,HIROSHI; Ohsaki, Makoto

    2015-01-01

    Dynamic finite element analyses of a four-story steel building frame modeled as a fine mesh of solid elements are performed using E-Simulator, which is a parallel finite element analysis software package for precisely simulating collapse behaviors of civil and building structures. E-Simulator is under development at the National Research Institute for Earth Science and Disaster Preventi